1801
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Saarela J, Sand J, Sorvajärvi T, Manninen A, Toivonen J. Transversely excited multipass photoacoustic cell using electromechanical film as microphone. Sensors (Basel) 2010; 10:5294-307. [PMID: 22219662 DOI: 10.3390/s100605294] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 11/17/2022]
Abstract
A novel multipass photoacoustic cell with five stacked electromechanical films as a microphone has been constructed, tested and characterized. The photoacoustic cell is an open rectangular structure with two steel plates facing each other. The longitudinal acoustic resonances are excited transversely in an optical multipass configuration. A detection limit of 22 ppb (10(-9)) was achieved for flowing NO(2) in N(2) at normal pressure by using the maximum of 70 laser beams between the resonator plates. The corresponding minimum detectable absorption and the normalized noise-equivalent absorption coefficients were 2.2 × 10(-7) cm(-1) and 3.2 × 10(-9) cm(-1) WHz(-1/2), respectively.
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1802
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Vogel M, Quint W, Nörtershäuser W. Trapped ion oscillation frequencies as sensors for spectroscopy. Sensors (Basel) 2010; 10:2169-87. [PMID: 22294921 PMCID: PMC3264474 DOI: 10.3390/s100302169] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 03/02/2010] [Accepted: 03/10/2010] [Indexed: 11/22/2022]
Abstract
The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microwave spectroscopy and their role in the determination of magnetic moments and excited state life-times. Also, the trap-assisted measurement of radiative nuclear de-excitations in the X-ray domain is discussed. This way, the different applications range over more than 12 orders of magnitude in the detectable photon energies, from below μeV in the microwave domain to beyond MeV in the X-ray domain.
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Affiliation(s)
- Manuel Vogel
- Department of Physics, Imperial College London, SW7 2AZ, London, UK
- Author to whom correspondence should be addressed; E-Mail:
| | - Wolfgang Quint
- GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany; E-Mail:
| | - Wilfried Nörtershäuser
- Nuclear Chemistry Department, Johannes-Gutenberg-Universität, D-55099 Mainz, Germany; E-Mail:
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1803
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Benalcazar WA, Chowdary PD, Jiang Z, Marks DL, Chaney EJ, Gruebele M, Boppart SA. High-Speed Nonlinear Interferometric Vibrational Imaging of Biological Tissue With Comparison to Raman Microscopy. IEEE J Quantum Electron 2009; 16:824-832. [PMID: 22058432 PMCID: PMC3207638 DOI: 10.1109/jstqe.2009.2035537] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vibrational contrast imaging of the distribution of complex biological molecules requires the use of techniques that provide broadband spectra with sufficient resolution. Coherent anti-Stokes Raman scattering (CARS) microscopy is currently limited in meeting these requirements due to the presence of a nonresonant background and its inability to target multiple resonances simultaneously. We present nonlinear interferometric vibrational imaging (NIVI), a technique based on CARS that uses femtosecond pump and Stokes pulses to retrieve broadband vibrational spectra over 200 cm(-1) (full-width at half maximum). By chirping the pump and performing spectral interferometric detection, the anti-Stokes pulses are resolved in time. This phase-sensitive detection allows suppression of not only the nonresonant background, but also of the real part of the nonlinear susceptibility χ((3)), improving the spectral resolution and features to make them comparable to those acquired with spontaneous Raman microscopy, as shown for a material sample and mammary tissue.
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Affiliation(s)
- Wladimir A. Benalcazar
- Department of Electrical and Computer Engineering, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Praveen D. Chowdary
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Zhi Jiang
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Daniel L. Marks
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Eric J. Chaney
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Martin Gruebele
- Departments of Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
| | - Stephen A. Boppart
- Departments of Electrical and Computer Engineering, Bioengineering, and Medicine, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA ()
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1804
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Iqbal A, Piper M, Faragher RGA, Naughton DP, Partridge L, Ostler EL. Chemical changes in aging Drosophila melanogaster. Age (Dordr) 2009; 31:343-351. [PMID: 19585275 PMCID: PMC2813051 DOI: 10.1007/s11357-009-9105-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
The “Green Theory” of aging proposes that organismal lifespan is limited by the failure to repair molecular damage generated by a broad range of metabolic processes. Two specific predictions arise from this: (1) that these processes will produce a wide variety of stable but dysfunctional compounds that increase in concentration with age, and (2) that organisms maintained under conditions that extend lifespan will display a reduced rate of accumulation of such “molecular rubbish”. To test these predictions, novel analytical techniques were developed to investigate the accumulation of damaged compounds in Drosophila melanogaster. Simple preparative techniques were developed to produce digests of whole D. melanogaster for use in three-dimensional (3D) fluorimetry and 1H NMR spectrometry. Cohorts of Drosophila maintained under normal conditions showed an age-related increase in signals consistent with damage whereas those maintained under conditions of low temperature and dietary restriction did not. 1H NMR revealed distinct age-associated spectral changes that will facilitate the identification of novel compounds that both increase and decrease during aging in this species. These findings are consistent with the predictions of the “Green Theory”.
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Affiliation(s)
- Aamira Iqbal
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton, UK BN2 4GJ
| | - Matthew Piper
- The Institute of Healthy Ageing, University College London, Gower St, London, UK WC1E 6BT
| | - Richard G. A. Faragher
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton, UK BN2 4GJ
| | - Declan P. Naughton
- School of Life Sciences, Kingston University, Penrhyn Road, Kingston-upon-Thames, UK KT1 2EE
| | - Linda Partridge
- The Institute of Healthy Ageing, University College London, Gower St, London, UK WC1E 6BT
| | - Elizabeth L. Ostler
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton, UK BN2 4GJ
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1805
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Graf RN, Robles FE, Chen X, Wax A. Detecting precancerous lesions in the hamster cheek pouch using spectroscopic white-light optical coherence tomography to assess nuclear morphology via spectral oscillations. J Biomed Opt 2009; 14:064030. [PMID: 20059268 PMCID: PMC2803719 DOI: 10.1117/1.3269680] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 10/08/2009] [Accepted: 10/09/2009] [Indexed: 05/19/2023]
Abstract
We have developed a novel dual-window approach for spectroscopic optical coherence tomography (OCT) measurements and applied it to probe nuclear morphology in tissue samples drawn from the hamster cheek pouch carcinogenesis model. The dual-window approach enables high spectral and depth resolution simultaneously, allowing detection of spectral oscillations, which we isolate to determine the structure of cell nuclei in the basal layer of the epithelium. The measurements were executed with our parallel frequency domain OCT system, which uses light from a thermal source, providing high bandwidth and access to the visible portion of the spectrum. The structural measurements show a highly statistically significant difference between untreated (normal) and treated (hyperplastic/dysplastic) tissues, indicating the potential utility of this approach as a diagnostic method.
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Affiliation(s)
- Robert N Graf
- Duke University, Department of Biomedical Engineering, 136 Hudson Hall, Durham, North Carolina 27708, USA
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1806
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McGee S, Mardirossian V, Elackattu A, Mirkovic J, Pistey R, Gallagher G, Kabani S, Yu CC, Wang Z, Badizadegan K, Grillone G, Feld MS. Anatomy-based algorithms for detecting oral cancer using reflectance and fluorescence spectroscopy. Ann Otol Rhinol Laryngol 2009; 118:817-826. [PMID: 19999369 PMCID: PMC2860948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
OBJECTIVES We used reflectance and fluorescence spectroscopy to noninvasively and quantitatively distinguish benign from dysplastic/malignant oral lesions. We designed diagnostic algorithms to account for differences in the spectral properties among anatomic sites (gingiva, buccal mucosa, etc). METHODS In vivo reflectance and fluorescence spectra were collected from 71 patients with oral lesions. The tissue was then biopsied and the specimen evaluated by histopathology. Quantitative parameters related to tissue morphology and biochemistry were extracted from the spectra. Diagnostic algorithms specific for combinations of sites with similar spectral properties were developed. RESULTS Discrimination of benign from dysplastic/malignant lesions was most successful when algorithms were designed for individual sites (area under the receiver operator characteristic curve [ROC-AUC],0.75 for the lateral surface of the tongue) and was least accurate when all sites were combined (ROC-AUC, 0.60). The combination of sites with similar spectral properties (floor of mouth and lateral surface of the tongue) yielded an ROC-AUC of 0.71. CONCLUSIONS Accurate spectroscopic detection of oral disease must account for spectral variations among anatomic sites. Anatomy-based algorithms for single sites or combinations of sites demonstrated good diagnostic performance in distinguishing benign lesions from dysplastic/malignant lesions and consistently performed better than algorithms developed for all sites combined.
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Affiliation(s)
- Sasha McGee
- G. R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge 02139, USA
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1807
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Lemaillet P, Ramella-Roman JC. Dynamic eye phantom for retinal oximetry measurements. J Biomed Opt 2009; 14:064008. [PMID: 20059246 PMCID: PMC2917460 DOI: 10.1117/1.3258669] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 09/09/2009] [Accepted: 09/15/2009] [Indexed: 05/22/2023]
Abstract
Measurements of oxygen saturation and flow in the retina can yield information about eye health and the onset of eye pathologies such as diabetic retinopathy. Recently, we developed a multiaperture camera that uses the division of the retinal image into several wavelength-sensitive subimages to compute retinal oxygen saturation. The calibration of such instruments is particularly difficult due to the layered structure of the eye and the lack of alternative measurement techniques. For this purpose, we realize an in vitro model of the human eye composed of a lens, the retina vessel, and three layers: the choroid, the retinal pigmented epithelium, and the sclera. The retinal vessel is modeled with a microtube connected to a micropump and a hemoglobin reservoir in a closed circulatory system. Hemoglobin oxygenation in the vessel could be altered using a reversible fuel cell. The sclera is represented by a Spectralon slab. The optical properties of the other layers are mimicked using titanium dioxide as a scatterer, ink as an absorber, and epoxy as a supporting structure. The optical thickness of each layer of the eye phantom is matched to each respective eye layer.
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Affiliation(s)
- Paul Lemaillet
- The Catholic University of America, 620 Michigan Avenue, North East, Washington, DC 20064, USA.
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1808
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Nazar MF, Khan AM, Shah SS. Microemulsion system with improved loading of piroxicam: a study of microstructure. AAPS PharmSciTech 2009; 10:1286-94. [PMID: 19876741 PMCID: PMC2799594 DOI: 10.1208/s12249-009-9328-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 10/13/2009] [Indexed: 11/30/2022] Open
Abstract
Formulation of a new oil-in-water (o/w) microemulsion composed of castor oil/Tween 80/ethanol/phosphate buffer for enhancing the loading capacity of an anti-inflammatory drug piroxicam has been accomplished. The pseudo-ternary phase diagram has been delineated at constant surfactant/cosurfactant ratio (1:2). The internal structure of so created four-component system was elucidated by means of an analysis of isotropic area magnitudes in the phase diagram. Conductivity (sigma), kinematic viscosity (keta), and surface tension (gamma) studies with the variation in Phiw (weight fraction of aqueous phase) show the occurrence of structural changes from water-in-oil (w/o) microemulsion to oil-in-water (o/w). Along with the solubility and partition studies of piroxicam in microemulsion components, the changes in the microstructure of the microemulsion after incorporation of drug have been evaluated using pH, sigma, gamma, keta, and density studies. Piroxicam, a poorly water-soluble drug displayed high solubility (1.0%) in an optimum microemulsion formulation using ethanol (55.0%), Tween 80 (26.5%), castor oil (7.5%), and phosphate buffer (11.0%). The results have shown that the microemulsion remained stable after the incorporation of piroxicam. Fluorescence spectra analysis taking pyrene as fluorescent probe was performed, and the results showed that pyrene was completely solubilized in the oil phases of the bicontinuous microemulsions. The fluorescence spectrum of the model drug piroxicam was used to probe the intramicellar region of nonionic microemulsion. The results showed that the piroxicam was localized in the interfacial film of microemulsion systems more deeply in the palisade layer with ethanol as the cosurfactant.
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Affiliation(s)
| | - Asad Muhammad Khan
- />Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad, Pakistan
- />Department of Chemistry, Forman Christian College (A Chartered University), 54600 Lahore, Pakistan
- />School of Science and Engineering, LUMS, Opposite U Block, DHA, 54792 Lahore, Pakistan
| | - Syed Sakhawat Shah
- />Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad, Pakistan
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1809
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Abstract
The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptide-membrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens.
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Affiliation(s)
- Diana E Schlamadinger
- Department of Chemistry and Biochemistry, University of California - San Diego, 9500 Gilman Drive, La Jolla, CA 92093
| | - Jonathan E Gable
- Department of Chemistry and Biochemistry, University of California - San Diego, 9500 Gilman Drive, La Jolla, CA 92093
| | - Judy E Kim
- Department of Chemistry and Biochemistry, University of California - San Diego, 9500 Gilman Drive, La Jolla, CA 92093
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1810
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Matson GB, Young K, Kaiser LG. RF pulses for in vivo spectroscopy at high field designed under conditions of limited power using optimal control. J Magn Reson 2009; 199:30-40. [PMID: 19398359 PMCID: PMC2724660 DOI: 10.1016/j.jmr.2009.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 03/27/2009] [Accepted: 03/27/2009] [Indexed: 05/26/2023]
Abstract
Localized in vivo spectroscopy at high magnetic field strength (>3T) is susceptible to localization artifacts such as the chemical shift artifact and the spatial interference artifact for J-coupled spins. This latter artifact results in regions of anomalous phase for J-coupled spins. These artifacts are exacerbated at high magnetic field due to the increased frequency dispersion, coupled with the limited RF pulse bandwidths used for localization. Approaches to minimize these artifacts include increasing the bandwidth of the frequency selective excitation pulses, and the use of frequency selective saturation pulses to suppress the signals in the regions with anomalous phase. The goal of this article is to demonstrate the efficacy of optimal control methods to provide broader bandwidth frequency selective pulses for in vivo spectroscopy in the presence of limited RF power. It is demonstrated by examples that the use of optimal control methods enable the generation of (i) improved bandwidth selective excitation pulses, (ii) more efficient selective inversion pulses to be used for generation of spin echoes, and (iii) improved frequency selective saturation pulses. While optimal control also allows for the generation of frequency selective spin echo pulses, it is argued that it is more efficient to use dual inversion pulses for broadband generation of spin echoes. Finally, the optimal control routines and example RF pulses are made available for downloading.
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Affiliation(s)
- Gerald B Matson
- Center for Imaging of Neurodegenerative Diseases (114M), Department of Veterans Affairs Medical Center, University of California, 4150 Clement Street, San Francisco, CA 94121, USA.
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1811
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Abstract
Progress in the development and application of nanoengineered systems is limited by the availability of quantitative measurement techniques. For the engineering of nanoparticle (NP)-based systems, single NP characterization is essential, but existing methods are slow and low throughput. We demonstrate a flow spectroscopy technique capable of analyzing hundreds of nanoparticles per second and use this technique for the high throughput analysis of nanoparticle surface-enhanced resonant Raman scattering (SERRS) tags. By measuring Rayleigh and Raman scattering from thousands of individual tags, tag preparations can be characterized based on their brightness and uniformity. The rapid analysis of individual nanoparticles using high spectral resolution flow spectroscopy will be useful in many areas of nanoengineering.
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1812
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D'Aléo A, Cecchetto E, De Cola L, Williams RM. Metal Ion Enhanced Charge Transfer in a Terpyridine-bis-Pyrene System. Sensors (Basel) 2009; 9:3604-26. [PMID: 22412328 DOI: 10.3390/s90503604] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 05/08/2009] [Accepted: 05/12/2009] [Indexed: 11/16/2022]
Abstract
The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4'-phenyl-2,2':6',2″-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both charge transfer (CT) absorption and CT emission. Furthermore, the study of the zinc complex as well as the bis-protonated form shows an enhancement of the electron transfer character of the system, by an increase of the acceptor strength. This is accompanied by a large increase of the non-radiative processes. With sub-nanosecond transient absorption spectroscopy, the CT state, consisting of the pyrene radical cation and the terpyridine radical anion, has been detected. At room temperature, the study of the nanosecond transient absorption spectra reveals the formation of a low-lying triplet excited state that we attribute to the pyrene moiety through which the CT state decays. At 77K, the absence of the terpyridine triplet emission also suggests the population of a low-lying triplet state of the pyrene unit.
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1813
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Licata SC, Jensen JE, Penetar DM, Prescot AP, Lukas SE, Renshaw PF. A therapeutic dose of zolpidem reduces thalamic GABA in healthy volunteers: a proton MRS study at 4 T. Psychopharmacology (Berl) 2009; 203:819-29. [PMID: 19125238 PMCID: PMC2818041 DOI: 10.1007/s00213-008-1431-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 11/30/2008] [Indexed: 11/29/2022]
Abstract
BACKGROUND Zolpidem is a nonbenzodiazepine sedative/hypnotic that acts at GABA(A) receptors to influence inhibitory neurotransmission throughout the central nervous system. A great deal is known about the behavioral effects of this drug in humans and laboratory animals, but little is known about zolpidem's specific effects on neurochemistry in vivo. OBJECTIVES We evaluated how acute administration of zolpidem affected levels of GABA, glutamate, glutamine, and other brain metabolites. MATERIALS AND METHODS Proton magnetic resonance spectroscopy ((1)H MRS) at 4 T was employed to measure the effects of zolpidem on brain chemistry in 19 healthy volunteers. Participants underwent scanning following acute oral administration of a therapeutic dose of zolpidem (10 mg) in a within-subject, single-blind, placebo-controlled, single-visit study. In addition to neurochemical measurements from single voxels within the anterior cingulate (ACC) and thalamus, a series of questionnaires were administered periodically throughout the experimental session to assess subjective mood states. RESULTS Zolpidem reduced GABA levels in the thalamus, but not the ACC. There were no treatment effects with respect to other metabolite levels. Self-reported ratings of "dizzy," "nauseous," "confused," and "bad effects" were increased relative to placebo, as were ratings on the sedation/intoxication (PCAG) and psychotomimetic/dysphoria (LSD) scales of the Addiction Research Center Inventory. Moreover, there was a significant correlation between the decrease in GABA and "dizzy." CONCLUSIONS Zolpidem engendered primarily dysphoric-like effects and the correlation between reduced thalamic GABA and "dizzy" may be a function of zolpidem's interaction with alpha1GABA(A) receptors in the cerebellum, projecting through the vestibular system to the thalamus.
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Affiliation(s)
- Stephanie C. Licata
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School
| | - J. Eric Jensen
- Brain Imaging Center, McLean Hospital/Harvard Medical School
| | - David M. Penetar
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School
| | | | - scott E. Lukas
- Behavioral Psychopharmacology Research Laboratory, McLean Hospital/Harvard Medical School,Brain Imaging Center, McLean Hospital/Harvard Medical School
| | - Perry F. Renshaw
- Brain Institute and Department of Psychiatry, University of Utah School of Medicine
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1814
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Price RB, Shungu DC, Mao X, Nestadt P, Kelly C, Collins KA, Murrough JW, Charney DS, Mathew SJ. Amino acid neurotransmitters assessed by proton magnetic resonance spectroscopy: relationship to treatment resistance in major depressive disorder. Biol Psychiatry 2009; 65:792-800. [PMID: 19058788 PMCID: PMC2934870 DOI: 10.1016/j.biopsych.2008.10.025] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 10/10/2008] [Accepted: 10/21/2008] [Indexed: 12/20/2022]
Abstract
BACKGROUND Significant alterations in gamma-aminobutyric acid (GABA) and glutamate levels have been previously reported in major depressive disorder (MDD); however, no studies to date have investigated associations between these amino acid neurotransmitters and treatment resistance. METHODS The objective of this study was to compare occipital cortex (OCC) and anterior cingulate cortex (ACC) GABA and glutamate+glutamine (Glx) levels measured by proton magnetic resonance spectroscopy ((1)H MRS) in 15 medication-free treatment-resistant depression (TRD) patients with those in 18 nontreatment-resistant MDD (nTRD) patients and 24 healthy volunteers (HVs). RESULTS Levels of OCC GABA relative to voxel tissue water (W) were decreased in TRD patients compared with both HV (20.2% mean reduction; p = .001; Cohen's d = 1.3) and nTRD subjects (16.4% mean reduction; p = .007; Cohen's d = 1.4). There was a similar main effect of diagnosis for ACC GABA/W levels (p = .047; Cohen's d = .76) with TRD patients exhibiting reduced GABA in comparison with the other two groups (22.4% to 24.5% mean reductions). Group differences in Glx/W were not significant in either brain region. Only GABA results in OCC survived correction for multiple comparisons. CONCLUSIONS Our findings corroborate previous reports of decreased GABA in MDD and provide initial evidence for a distinct neuronal amino acid profile in patients who have failed to respond to several standard antidepressants, possibly indicative of abnormal glutamate/glutamine/GABA cycling. Given interest in novel antidepressant mechanisms in TRD that selectively target amino acid neurotransmitter function, the translational relevance of these findings awaits further study.
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Affiliation(s)
- Rebecca B. Price
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, Department of Psychology, Rutgers, the State University of New Jersey
| | - Dikoma C. Shungu
- Department of Radiology, Weill Medical College of Cornell University, New York, NY
| | - Xiangling Mao
- Department of Radiology, Weill Medical College of Cornell University, New York, NY
| | - Paul Nestadt
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY
| | - Chris Kelly
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY
| | | | - James W. Murrough
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY
| | - Dennis S. Charney
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, Department of Pharmacology & Systems Therapeutics, Mount Sinai School of Medicine, New York, NY
| | - Sanjay J. Mathew
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY
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1815
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Lau C, Sćepanović O, Mirkovic J, McGee S, Yu CC, Fulghum S, Wallace M, Tunnell J, Bechtel K, Feld M. Re-evaluation of model-based light-scattering spectroscopy for tissue spectroscopy. J Biomed Opt 2009; 14:024031. [PMID: 19405760 PMCID: PMC2866094 DOI: 10.1117/1.3116708] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 02/09/2009] [Accepted: 02/10/2009] [Indexed: 05/19/2023]
Abstract
Model-based light scattering spectroscopy (LSS) seemed a promising technique for in-vivo diagnosis of dysplasia in multiple organs. In the studies, the residual spectrum, the difference between the observed and modeled diffuse reflectance spectra, was attributed to single elastic light scattering from epithelial nuclei, and diagnostic information due to nuclear changes was extracted from it. We show that this picture is incorrect. The actual single scattering signal arising from epithelial nuclei is much smaller than the previously computed residual spectrum, and does not have the wavelength dependence characteristic of Mie scattering. Rather, the residual spectrum largely arises from assuming a uniform hemoglobin distribution. In fact, hemoglobin is packaged in blood vessels, which alters the reflectance. When we include vessel packaging, which accounts for an inhomogeneous hemoglobin distribution, in the diffuse reflectance model, the reflectance is modeled more accurately, greatly reducing the amplitude of the residual spectrum. These findings are verified via numerical estimates based on light propagation and Mie theory, tissue phantom experiments, and analysis of published data measured from Barrett's esophagus. In future studies, vessel packaging should be included in the model of diffuse reflectance and use of model-based LSS should be discontinued.
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Affiliation(s)
- Condon Lau
- Massachusetts Institute of Technology, George R. Harrison Spectroscopy Laboratory, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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1816
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Niedzwiedzki DM, Sandberg DJ, Cong H, Sandberg MN, Gibson GN, Birge RR, Frank HA. Ultrafast time-resolved absorption spectroscopy of geometric isomers of carotenoids. Chem Phys 2009; 357:4. [PMID: 20174614 PMCID: PMC2823300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The structures of a number of stereoisomers of carotenoids have been revealed in three-dimensional X-ray crystallographic investigations of pigment-protein complexes from photosynthetic organisms. Despite these structural elucidations, the reason for the presence of stereoisomers in these systems is not well understood. An important unresolved issue is whether the natural selection of geometric isomers of carotenoids in photosynthetic pigment-protein complexes is determined by the structure of the protein binding site or by the need for the organism to accomplish a specific physiological task. The association of cis isomers of a carotenoid with reaction centers and trans isomers of the same carotenoid with light-harvesting pigment-protein complexes has led to the hypothesis that the stereoisomers play distinctly different physiological roles. A systematic investigation of the photophysics and photochemistry of purified, stable geometric isomers of carotenoids is needed to understand if a relationship between stereochemistry and biological function exists. In this work we present a comparative study of the spectroscopy and excited state dynamics of cis and trans isomers of three different open-chain carotenoids in solution. The molecules are neurosporene (n = 9), spheroidene (n = 10), and spirilloxanthin (n = 13), where n is the number of conjugated pi-electron double bonds. The spectroscopic experiments were carried out on geometric isomers of the carotenoids purified by high performance liquid chromatography (HPLC) and then frozen to 77 K to inhibit isomerization. The spectral data taken at 77 K provide a high resolution view of the spectroscopic differences between geometric isomers. The kinetic data reveal that the lifetime of the lowest excited singlet state of a cis-isomer is consistently shorter than that of its corresponding all-trans counterpart despite the fact that the excited state energy of the cis molecule is typically higher than that of the trans molecule. Quantum theoretical calculations on an n = 9 linear polyene were carried out to examine this process. The calculations indicate that the electronic coupling terms are significantly higher for the cis isomer, and when combined with the Franck-Condon factors, predict internal conversion rates roughly double those of the all-trans species. The electronic effects more than offset the decrease in coupling efficiencies associated with the higher system origin energies and explain the observed shorter cis isomer lifetimes.
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Affiliation(s)
- Dariusz M. Niedzwiedzki
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
| | - Daniel J. Sandberg
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
| | - Hong Cong
- Department of Physics, University of Connecticut, Storrs, CT 06269-3046, USA
| | - Megan N. Sandberg
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
| | - George N. Gibson
- Department of Physics, University of Connecticut, Storrs, CT 06269-3046, USA
| | - Robert R. Birge
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
| | - Harry A. Frank
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
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1817
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Samiotakis A, Wittung-Stafshede P, Cheung MS. Folding, stability and shape of proteins in crowded environments: experimental and computational approaches. Int J Mol Sci 2009; 10:572-88. [PMID: 19333422 DOI: 10.3390/ijms10020572] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 02/10/2009] [Accepted: 02/12/2009] [Indexed: 11/17/2022] Open
Abstract
How the crowded environment inside cells affects folding, stability and structures of proteins is a vital question, since most proteins are made and function inside cells. Here we describe how crowded conditions can be created in vitro and in silico and how we have used this to probe effects on protein properties. We have found that folded forms of proteins become more compact in the presence of macromolecular crowding agents; if the protein is aspherical, the shape also changes (extent dictated by native-state stability and chemical conditions). It was also discovered that the shape of the macromolecular crowding agent modulates the folding mechanism of a protein; in addition, the extent of asphericity of the protein itself is an important factor in defining its folding speed.
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1818
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Lo J, Chen SJ, Fang Q, Papaioannou T, Kim ES, Gundersen M, Marcu L. Performance of a diaphragmed microlens for a packaged microspectrometer. Sensors (Basel) 2009; 9:859-68. [PMID: 22399943 PMCID: PMC3280835 DOI: 10.3390/s90200859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 01/09/2009] [Accepted: 02/04/2009] [Indexed: 05/31/2023]
Abstract
This paper describes the design, fabrication, packaging and testing of a microlens integrated in a multi-layered MEMS microspectrometer. The microlens was fabricated using modified PDMS molding to form a suspended lens diaphragm. Gaussian beam propagation model was used to measure the focal length and quantify M(2) value of the microlens. A tunable calibration source was set up to measure the response of the packaged device. Dual wavelength separation by the packaged device was demonstrated by CCD imaging and beam profiling of the spectroscopic output. We demonstrated specific techniques to measure critical parameters of microoptics systems for future optimization of spectroscopic devices.
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Affiliation(s)
- Joe Lo
- Biomedical Engineering, University of Southern California, Los Angeles, CA, USA; E-Mail:
| | - Shih-Jui Chen
- Electrical Engineering and Electrophysics, University of Southern California, Los Angeles, CA USA; E-Mails: ; ;
| | - Qiyin Fang
- Cedars Sinai Medical Center, Los Angeles, CA, USA; E-Mail:
- Engineering Physics, McMaster University, Hamilton, Ontario, Canada; E-Mail:
| | | | - Eun-Sok Kim
- Electrical Engineering and Electrophysics, University of Southern California, Los Angeles, CA USA; E-Mails: ; ;
| | - Martin Gundersen
- Electrical Engineering and Electrophysics, University of Southern California, Los Angeles, CA USA; E-Mails: ; ;
| | - Laura Marcu
- Biomedical Engineering, University of California at Davis, USA
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1819
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Hellriegel C, Gratton E. Real-time multi-parameter spectroscopy and localization in three-dimensional single-particle tracking. J R Soc Interface 2009; 6 Suppl 1:S3-14. [PMID: 18753123 PMCID: PMC2706464 DOI: 10.1098/rsif.2008.0313.focus] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 07/30/2008] [Indexed: 11/12/2022] Open
Abstract
Tracking of single particles in optical microscopy has been employed in studies ranging from material sciences to biophysics down to the level of single molecules. The technique intrinsically circumvents ensemble averaging and may therefore reveal directly mechanistic details of the involved dynamic processes. Such processes range from translational and rotational motion to spectral dynamics. We distinguish between conventional a posteriori tracking of objects (e.g. from the sequences of images) and the experimentally more refined 'on-the-fly' tracking technique. In this technique, the observation volume of the microscope is kept centred with respect to the moving object via a feedback algorithm. This approach brings a series of advantages in comparison with the tracking from images, ranging from a superior spatio-temporal resolution (2-50nm and 1-32ms) to the capability of inferring additional data (e.g. fluorescence lifetime, emission spectrum, polarization, intensity dynamics) from an object as it moves over several microns in three dimensions. In this contribution, we describe the principle of the tracking technique as implemented on a two-photon laser scanning microscope and illustrate its capabilities with experimental data, from particles labelled with different dyes moving in a liquid to the characterization of small fluorescently labelled protein assemblies in living cells.
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Affiliation(s)
- Christian Hellriegel
- />Laboratory for Fluorescence Dynamics and Department of Biomedical Engineering, University of California Irvine3120 Natural Sciences II, Irvine, CA 92697, USA
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1820
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Bebiano D, Alfaro SCA. A weld defects detection system based on a spectrometer. Sensors (Basel) 2009; 9:2851-61. [PMID: 22574049 PMCID: PMC3348795 DOI: 10.3390/s90402851] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 04/07/2009] [Accepted: 04/20/2009] [Indexed: 11/16/2022]
Abstract
Improved product quality and production methods, and decreased production costs are important objectives of industries. Welding processes are part of this goal. There are many studies about monitoring and controlling welding process. This work presents a non-intrusive on-line monitoriment system and some algorithms capable of detecting GTAW weld defects. Some experiments were made to simulate weld defects by disturbing the electric arc. The data comes from a spectrometer which captures perturbations on the electric arc by the radiation emission of chosen lines. Algorithms based on change detection methods are used to indicate the presence and localization of those defects.
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Affiliation(s)
- Daniel Bebiano
- Automation and Control Group, University of Brasilia, Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, Brasília - DF, Brazil. CEP: 70910-900; E-Mail:
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1821
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Srivastava AK, Deepa M, Bhandari S, Fuess H. Tunable Nanostructures and Crystal Structures in Titanium Oxide Films. Nanoscale Res Lett 2009; 4:54-62. [PMID: 20596447 PMCID: PMC2893905 DOI: 10.1007/s11671-008-9202-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 10/27/2008] [Indexed: 05/29/2023]
Abstract
Controllable nanostructures in spin coated titanium oxide (TiO(2)) films have been achieved by a very simple means, through change of post deposition annealing temperature. Electron beam imaging and reciprocal space analysis revealed as-deposited TiO(2) films to be characterized by a dominant anatase phase which converts to the rutile form at 600 degrees C and reverts to the anatase modification at 1,200 degrees C. The phase changes are also accompanied by changes in the film microstructure: from regular nanoparticles (as-deposited) to nanowires (600 degrees C) and finally to dendrite like shapes at 1,200 degrees C. Photoluminescence studies, Raman spectral results, and X-ray diffraction data also furnish evidence in support of the observed solid state phase transformations in TiO(2).
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Affiliation(s)
- AK Srivastava
- Division of Materials Characterization, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, 110012, India
| | - M Deepa
- Division of Materials Characterization, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, 110012, India
| | - S Bhandari
- Division of Materials Characterization, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, 110012, India
| | - H Fuess
- Technische Universität Darmstadt, Darmstadt, D-64287, Germany
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1822
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Pavlova I, Weber CR, Schwarz RA, Williams MD, Gillenwater AM, Richards-Kortum R. Fluorescence spectroscopy of oral tissue: Monte Carlo modeling with site-specific tissue properties. J Biomed Opt 2009; 14:014009. [PMID: 19256697 PMCID: PMC2722954 DOI: 10.1117/1.3065544] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A Monte Carlo model with site-specific input is used to predict depth-resolved fluorescence spectra from individual normal, inflammatory, and neoplastic oral sites. Our goal in developing this model is to provide a computational tool to study how the morphological characteristics of the tissue affect clinically measured spectra. Tissue samples from the measured sites are imaged using fluorescence confocal microscopy; autofluorescence patterns are measured as a function of depth and tissue sublayer for each individual site. These fluorescence distributions are used as input to the Monte Carlo model to generate predictions of fluorescence spectra, which are compared to clinically measured spectra on a site-by-site basis. A lower fluorescence intensity and longer peak emission wavelength observed in clinical spectra from dysplastic and cancerous sites are found to be associated with a decrease in measured fluorescence originating from the stroma or deeper fibrous regions, and an increase in the measured fraction of photons originating from the epithelium or superficial tissue layers. The simulation approach described here can be used to suggest an optical probe design that samples fluorescence at a depth that gives optimal separation in the spectral signal measured for benign, dysplastic, and cancerous oral mucosa.
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Affiliation(s)
- Ina Pavlova
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712
| | | | | | - Michelle D. Williams
- Department of Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Ann M. Gillenwater
- Department of Head and Neck Surgery, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
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1823
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Hiremath PS, Saha RN. Controlled release hydrophilic matrix tablet formulations of isoniazid: design and in vitro studies. AAPS PharmSciTech 2008; 9:1171-8. [PMID: 19015997 PMCID: PMC2628280 DOI: 10.1208/s12249-008-9159-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2008] [Accepted: 10/22/2008] [Indexed: 11/30/2022] Open
Abstract
The aim of the present investigation was to develop oral controlled release matrix tablet formulations of isoniazid using hydroxypropyl methylcellulose (HPMC) as a hydrophilic release retardant polymer and to study the influence of various formulation factors like proportion of the polymer, polymer viscosity grade, compression force, and release media on the in vitro release characteristics of the drug. The formulations were developed using wet granulation technology. The in vitro release studies were performed using US Pharmacopoeia type 1 apparatus (basket method) in 900 ml of pH 7.4 phosphate buffer at 100 rpm. The release kinetics was analyzed using Korsmeyer-Peppas model. The release profiles were also analyzed using statistical method (one-way analysis of variance) and f (2) metric values. The release profiles found to follow Higuchi's square root kinetics model irrespective of the polymer ratio and the viscosity grade used. The results in the present investigation confirm that the release rate of the drug from the HPMC matrices is highly influenced by the drug/HPMC ratio and viscosity grade of the HPMC. Also, the effect of compression force and release media was found to be significant on the release profiles of isoniazid from HPMC matrix tablets. The release mechanism was found to be anomalous non-Fickian diffusion in all the cases. In the present investigation, a series of controlled release formulations of isoniazid were developed with different release rates and duration so that these formulations could further be assessed from the in vivo bioavailability studies. The formulations were found to be stable and reproducible.
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Affiliation(s)
- Praveen S Hiremath
- Pharmacy Group, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
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1824
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McGee S, Mirkovic J, Mardirossian V, Elackattu A, Yu CC, Kabani S, Gallagher G, Pistey R, Galindo L, Badizadegan K, Wang Z, Dasari R, Feld MS, Grillone G. Model-based spectroscopic analysis of the oral cavity: impact of anatomy. J Biomed Opt 2008; 13:064034. [PMID: 19123680 PMCID: PMC2629646 DOI: 10.1117/1.2992139] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In order to evaluate the impact of anatomy on the spectral properties of oral tissue, we used reflectance and fluorescence spectroscopy to characterize nine different anatomic sites. All spectra were collected in vivo from healthy oral mucosa. We analyzed 710 spectra collected from the oral cavity of 79 healthy volunteers. From the spectra, we extracted spectral parameters related to the morphological and biochemical properties of the tissue. The parameter distributions for the nine sites were compared, and we also related the parameters to the physical properties of the tissue site. k-Means cluster analysis was performed to identify sites or groups of sites that showed similar or distinct spectral properties. For the majority of the spectral parameters, certain sites or groups of sites exhibited distinct parameter distributions. Sites that are normally keratinized, most notably the hard palate and gingiva, were distinct from nonkeratinized sites for a number of parameters and frequently clustered together. The considerable degree of spectral contrast (differences in the spectral properties) between anatomic sites was also demonstrated by successfully discriminating between several pairs of sites using only two spectral parameters. We tested whether the 95% confidence interval for the distribution for each parameter, extracted from a subset of the tissue data could correctly characterize a second set of validation data. Excellent classification accuracy was demonstrated. Our results reveal that intrinsic differences in the anatomy of the oral cavity produce significant spectral contrasts between various sites, as reflected in the extracted spectral parameters. This work provides an important foundation for guiding the development of spectroscopic-based diagnostic algorithms for oral cancer.
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Affiliation(s)
- Sasha McGee
- Massachusetts Institute of Technology, G.R. Harrison Spectroscopy Laboratory, Building 6-205, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
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1825
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Levin I, Vanderah T. Workshop on Measurement Needs for Local-Structure Determination in Inorganic Materials. J Res Natl Inst Stand Technol 2008; 113:321-333. [PMID: 27096131 PMCID: PMC4652865 DOI: 10.6028/jres.113.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 08/12/2008] [Indexed: 06/05/2023]
Abstract
The functional responses (e.g., dielectric, magnetic, catalytic, etc.) of many industrially-relevant materials are controlled by their local structure-a term that refers to the atomic arrangements on a scale ranging from atomic (sub-nanometer) to several nanometers. Thus, accurate knowledge of local structure is central to understanding the properties of nanostructured materials, thereby placing the problem of determining atomic positions on the nanoscale-the so-called "nanostructure problem"-at the center of modern materials development. Today, multiple experimental techniques exist for probing local atomic arrangements; nonetheless, finding accurate comprehensive, and robust structural solutions for the nanostructured materials still remains a formidable challenge because any one of these methods yields only a partial view of the local structure. The primary goal of this 2-day NIST-sponsored workshop was to bring together experts in the key experimental and theoretical areas relevant to local-structure determination to devise a strategy for the collaborative effort required to develop a comprehensive measurement solution on the local scale. The participants unanimously agreed that solving the nanostructure problem-an ultimate frontier in materials characterization-necessitates a coordinated interdisciplinary effort that transcends the existing capabilities of any single institution, including national laboratories, centers, and user facilities. The discussions converged on an institute dedicated to local structure determination as the most viable organizational platform for successfully addressing the nanostructure problem. The proposed "institute" would provide an intellectual infrastructure for local structure determination by (1) developing and maintaining relevant computer software integrated in an open-source global optimization framework (Fig. 2), (2) connecting industrial and academic users with experts in measurement techniques, (3) developing and maintaining pertinent databases, and (4) providing necessary education and training.
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1826
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Kaiser LG, Young K, Matson GB. Numerical simulations of localized high field 1H MR spectroscopy. J Magn Reson 2008; 195:67-75. [PMID: 18789736 PMCID: PMC2585774 DOI: 10.1016/j.jmr.2008.08.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 08/22/2008] [Accepted: 08/22/2008] [Indexed: 05/08/2023]
Abstract
The limited bandwidths of volume selective RF pulses in localized in vivo MRS experiments introduce spatial artifacts that complicate spectral quantification of J-coupled metabolites. These effects are commonly referred to as a spatial interference or "four compartment" artifacts and are more pronounced at higher field strengths. The main focus of this study is to develop a generalized approach to numerical simulations that combines full density matrix calculations with 3D localization to investigate the spatial artifacts and to provide accurate prior knowledge for spectral fitting. Full density matrix calculations with 3D localization using experimental pulses were carried out for PRESS (TE=20, 70 ms), STEAM (TE=20, 70 ms) and LASER (TE=70 ms) pulse sequences and compared to non-localized simulations and to phantom solution data at 4 T. Additional simulations at 1.5 and 7 T were carried out for STEAM and PRESS (TE=20 ms). Four brain metabolites that represented a range from weak to strong J-coupling networks were included in the simulations (lactate, N-acetylaspartate, glutamate and myo-inositol). For longer TE, full 3D localization was necessary to achieve agreement between the simulations and phantom solution spectra for the majority of cases in all pulse sequence simulations. For short echo time (TE=20 ms), ideal pulses without localizing gradients gave results that were in agreement with phantom results at 4 T for STEAM, but not for PRESS (TE=20). Numerical simulations that incorporate volume localization using experimental RF pulses are shown to be a powerful tool for generation of accurate metabolic basis sets for spectral fitting and for optimization of experimental parameters.
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Affiliation(s)
- Lana G Kaiser
- Northern California Institute for Research and Education, San Francisco, CA 97121, USA.
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1827
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Roy HK, Turzhitsky V, Kim YL, Goldberg MJ, Muldoon JP, Liu Y, Brand RE, Hall C, Hasabou N, Jameel M, Backman V. Spectral slope from the endoscopically-normal mucosa predicts concurrent colonic neoplasia: a pilot ex-vivo clinical study. Dis Colon Rectum 2008; 51:1381-6. [PMID: 18536963 PMCID: PMC2913285 DOI: 10.1007/s10350-008-9384-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 01/25/2008] [Accepted: 02/23/2008] [Indexed: 02/06/2023]
Abstract
PURPOSE We previously reported that analysis of histologically normal intestinal epithelium for spectral slope, a marker for aberrations in nanoscale tissue architecture, had outstanding accuracy in identifying field carcinogenesis in preclinical colorectal cancer models. In this study, we assessed the translatability of spectral slope analysis to human colorectal cancer screening. METHODS Subjects (n = 127) undergoing colonoscopy had spectral slope determined from two endoscopically normal midtransverse colonic biopsies using four-dimensional elastic light-scattering fingerprinting and correlated with clinical findings. RESULTS Four-dimensional elastic light-scattering fingerprinting analysis showed the submicron particles size progressively shifted toward larger sizes in subjects harboring neoplasia. There was a corresponding decrease in spectral slope values from the endoscopically normal mucosa in subjects harboring adenomas (n = 41) and advanced adenomas (n = 10), compared to neoplasia-free subjects (P </= 0.00001). These factors did not appear to be confounded by either age or adenoma location. For detecting advanced adenomas, spectral slope had a negative and positive predictive value of 95 percent and 50 percent respectively. CONCLUSIONS We demonstrate, for the first time, that spectral slope in "normal" mucosa can accurately risk-stratify patients for colonic neoplasia. This proof of concept study serves to underscore the promise of four-dimensional elastic light-scattering fingerprinting analysis for colorectal cancer screening.
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Affiliation(s)
- Hemant K. Roy
- Department of Internal Medicine, Evanston-Northwestern Healthcare Evanston IL
| | | | - Young L. Kim
- Biomedical Engineering Department, Northwestern University Evanston, IL
| | - Michael J. Goldberg
- Department of Internal Medicine, Evanston-Northwestern Healthcare Evanston IL
| | | | - Yang Liu
- Biomedical Engineering Department, Northwestern University Evanston, IL
| | - Randall E. Brand
- Department of Internal Medicine, Evanston-Northwestern Healthcare Evanston IL
| | - Curtis Hall
- Department of Pathology, Evanston-Northwestern Healthcare Evanston IL
| | - Nahla Hasabou
- Department of Internal Medicine, Evanston-Northwestern Healthcare Evanston IL
| | - Mohammed Jameel
- Department of Internal Medicine, Evanston-Northwestern Healthcare Evanston IL
| | - Vadim Backman
- Biomedical Engineering Department, Northwestern University Evanston, IL
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1828
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Abergel RJ, Clifton MC, Pizarro JC, Warner JA, Shuh DK, Strong RK, Raymond KN. The siderocalin/enterobactin interaction: a link between mammalian immunity and bacterial iron transport. J Am Chem Soc 2008; 130:11524-34. [PMID: 18680288 PMCID: PMC3188318 DOI: 10.1021/ja803524w] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The siderophore enterobactin (Ent) is produced by enteric bacteria to mediate iron uptake. Ent scavenges iron and is taken up by the bacteria as the highly stable ferric complex [Fe (III)(Ent)] (3-). This complex is also a specific target of the mammalian innate immune system protein, Siderocalin (Scn), which acts as an antibacterial agent by specifically sequestering siderophores and their ferric complexes during infection. Recent literature suggesting that Scn may also be involved in cellular iron transport has increased the importance of understanding the mechanism of siderophore interception and clearance by Scn; Scn is observed to release iron in acidic endosomes and [Fe (III)(Ent)] (3-) is known to undergo a change from catecholate to salicylate coordination in acidic conditions, which is predicted to be sterically incompatible with the Scn binding pocket (also referred to as the calyx). To investigate the interactions between the ferric Ent complex and Scn at different pH values, two recombinant forms of Scn with mutations in three residues lining the calyx were prepared: Scn-W79A/R81A and Scn-Y106F. Binding studies and crystal structures of the Scn-W79A/R81A:[Fe (III)(Ent)] (3-) and Scn-Y106F:[Fe (III)(Ent)] (3-) complexes confirm that such mutations do not affect the overall conformation of the protein but do weaken significantly its affinity for [Fe (III)(Ent)] (3-). Fluorescence, UV-vis, and EXAFS spectroscopies were used to determine Scn/siderophore dissociation constants and to characterize the coordination mode of iron over a wide pH range, in the presence of both mutant proteins and synthetic salicylate analogues of Ent. While Scn binding hinders salicylate coordination transformation, strong acidification results in the release of iron and degraded siderophore. Iron release may therefore result from a combination of Ent degradation and coordination change.
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Affiliation(s)
- Rebecca J. Abergel
- Department of Chemistry, University of California, Berkeley, CA 94720-1460
| | - Matthew C. Clifton
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Juan C. Pizarro
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Jeffrey A. Warner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - David K. Shuh
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Roland K. Strong
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, CA 94720-1460
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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1829
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Otberg N, Grone D, Meyer L, Schanzer S, Hoffmann G, Ackermann H, Sterry W, Lademann J. Water-filtered infrared-A (wIRA) can act as a penetration enhancer for topically applied substances. Ger Med Sci 2008; 6:Doc08. [PMID: 19675735 PMCID: PMC2703260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 06/30/2008] [Indexed: 11/03/2022]
Abstract
BACKGROUND Water-filtered infrared-A (wIRA) irradiation has been shown to enhance penetration of clinically used topically applied substances in humans through investigation of functional effects of penetrated substances like vasoconstriction by cortisone. AIM OF THE STUDY Investigation of the influence of wIRA irradiation on the dermatopharmacokinetics of topically applied substances by use of optical methods, especially to localize penetrating substances, in a prospective randomised controlled study in humans. METHODS The penetration profiles of the hydrophilic dye fluorescein and the lipophilic dye curcumin in separate standard water-in-oil emulsions were determined on the inner forearm of test persons by tape stripping in combination with spectroscopic measurements. Additionally, the penetration was investigated in vivo by laser scanning microscopy. Transepidermal water loss, hydration of the epidermis, and surface temperature were determined. Three different procedures (modes A, B, C) were used in a randomised order on three separate days of investigation in each of 12 test persons. In mode A, the two dyes were applied on different skin areas without water-filtered infrared-A (wIRA) irradiation. In mode B, the skin surface was irradiated with wIRA over 30 min before application of the two dyes (Hydrosun radiator type 501, 10 mm water cuvette, orange filter OG590, water-filtered spectrum: 590-1400 nm with dominant amount of wIRA). In mode C, the two dyes were applied and immediately afterwards the skin was irradiated with wIRA over 30 min. In all modes, tape stripping started 30 min after application of the formulations. Main variable of interest was the ratio of the amount of the dye in the deeper (second) 10% of the stratum corneum to the amount of the dye in the upper 10% of the stratum corneum. RESULTS The penetration profiles of the hydrophilic fluorescein showed in case of pretreatment or treatment with wIRA (modes B and C) an increased penetration depth compared to the non-irradiated skin (mode A): The ratio of the amount of the dye in the deeper (second) 10% of the stratum corneum to the amount of the dye in the upper 10% of the stratum corneum showed medians and interquartile ranges for mode A of 0.017 (0.007/0.050), for mode B of 0.084 (0.021/0.106), for mode C of 0.104 (0.069/0.192) (difference between modes: p=0.0112, significant; comparison mode A with mode C: p<0.01, significant). In contrast to fluorescein, the lipophilic curcumin showed no differences in the penetration kinetics, in reference to whether the skin was irradiated with wIRA or not. These effects were confirmed by laser scanning microscopy. Water-filtered infrared-A irradiation increased the hydration of the stratum corneum: transepidermal water loss rose from approximately 8.8 g m(-2) h(-1) before wIRA irradiation to 14.2 g m(-2) h(-1) after wIRA irradiation and skin hydration rose from 67 to 87 relative units. Skin surface temperature increased from 32.8 degrees C before wIRA to 36.4 degrees C after wIRA irradiation. DISCUSSION The better penetration of the hydrophilic dye fluorescein after or during skin irradiation (modes B and C) can be explained by increased hydration of the stratum corneum by irradiation with wIRA. CONCLUSIONS As most topically applied substances for the treatment of patients are mainly hydrophilic, wIRA can be used to improve the penetration of substances before or after application of substances - in the first case even of thermolabile substances - with a broad clinical relevance as a contact free alternative to an occlusive dressing.
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Affiliation(s)
- Nina Otberg
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany
| | - Diego Grone
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany
| | - Lars Meyer
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany
| | - Sabine Schanzer
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany
| | - Gerd Hoffmann
- Institute of Sports Sciences, Johann Wolfgang Goethe University, Frankfurt/Main, Germany
| | - Hanns Ackermann
- Department of Biomathematics, Johann Wolfgang Goethe University, Frankfurt/Main, Germany
| | - Wolfram Sterry
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany
| | - Jürgen Lademann
- Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Berlin, Germany,*To whom correspondence should be addressed: Jürgen Lademann, Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, University Medicine Charité, Schumannstr. 20/21, D-10117 Berlin, Germany, Tel.: +49 30 450 518 235, Fax: +49 30 450 518 918, E-mail:
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1830
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Esmonde-White KA, Le Clair SV, Roessler BJ, Morris MD. Effect of conformation and drop properties on surface-enhanced Raman spectroscopy of dried biopolymer drops. Appl Spectrosc 2008; 62:503-11. [PMID: 18498691 PMCID: PMC3077080 DOI: 10.1366/000370208784344370] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Biofluids are complex solutions consisting of small ions and large biopolymers such as DNA, proteins, or proteoglycans. Biopolymers affect fluid properties but their effect on drop deposition has not been examined. Hyaluronic acid (HA), an important component in synovial fluid, was chosen as a model biopolymer, and examined using surface-enhanced Raman spectroscopy (SERS). Nanoliter volumes of HA solutions were dried onto a patterned SERS substrate and spectra were collected from the dried hyaluronic acid drops with a near-infrared Raman microscope. Characteristic hyaluronic acid bands were examined. Capillary viscometry measured properties of HA solutions, and entanglement behavior was also modeled using scaling theory principles. Viscosity measurements were incorporated into models of suspended particle droplets to account for the effect of inter-chain attraction on droplet formation. Microscope images were used to evaluate the shape of the dried drop. Relative drop thickness was estimated from concentric rings found at drop edges using established models of light interference by thin films. We found SERS spectra were sensitive not only to polymer conformation, but also to type of deposition (ring versus uniform), and the thickness of the resulting deposition. These data suggest an approach to elucidate the effects of biopolymers and dehydrated biofluids on SERS analysis.
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Affiliation(s)
- Karen A Esmonde-White
- Department of Biomedical Engineering, University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, USA
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1831
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Lee TK, Baron ED, Foster TH. Monitoring Pc 4 photodynamic therapy in clinical trials of cutaneous T-cell lymphoma using noninvasive spectroscopy. J Biomed Opt 2008; 13:030507. [PMID: 18601524 PMCID: PMC2527126 DOI: 10.1117/1.2939068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Silicon phthalocyanine Pc 4 photodynamic therapy (Pc 4-PDT) has emerged as a potentially effective treatment for cutaneous T-cell lymphoma (CTCL). Noninvasive reflectance and fluorescence spectroscopy before, during, and after PDT may provide useful dose metrics and enable therapy to be tailored to individual lesions. We present the design and implementation of a portable bedside spectroscopy system for initial clinical trials of Pc 4-PDT of CTCL. Reflectance and fluorescence spectra were obtained from an early stage CTCL patient throughout the course of the PDT treatment. Preliminary patient data show a significant effect of Pc 4 on the tissue absorption, modest Pc 4 photobleaching, and heterogeneity of Pc 4 within and between the lesions.
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Affiliation(s)
- Tammy K. Lee
- University of Rochester, Institute of Optics and Department of Imaging Sciences, Rochester, New York 14642
| | - Elma D. Baron
- Case Western Reserve University, University Hospitals of Cleveland, Department of Dermatology, Cleveland, Ohio 44106
| | - Thomas H. Foster
- University of Rochester, Institute of Optics and Department of Imaging Sciences, Rochester, New York 14642
- Tel: 585–275–1347; E-mail:
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1832
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Zhu C, Palmer GM, Breslin TM, Harter J, Ramanujam N. Diagnosis of breast cancer using fluorescence and diffuse reflectance spectroscopy: a Monte-Carlo-model-based approach. J Biomed Opt 2008; 13:034015. [PMID: 18601560 PMCID: PMC2791791 DOI: 10.1117/1.2931078] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We explore the use of Monte-Carlo-model-based approaches for the analysis of fluorescence and diffuse reflectance spectra measured ex vivo from breast tissues. These models are used to extract the absorption, scattering, and fluorescence properties of malignant and nonmalignant tissues and to diagnose breast cancer based on these intrinsic tissue properties. Absorption and scattering properties, including beta-carotene concentration, total hemoglobin concentration, hemoglobin saturation, and the mean reduced scattering coefficient are derived from diffuse reflectance spectra using a previously developed Monte Carlo model of diffuse reflectance. A Monte Carlo model of fluorescence described in an earlier manuscript was employed to retrieve the intrinsic fluorescence spectra. The intrinsic fluorescence spectra were decomposed into several contributing components, which we attribute to endogenous fluorophores that may present in breast tissues including collagen, NADH, and retinol/vitamin A. The model-based approaches removes any dependency on the instrument and probe geometry. The relative fluorescence contributions of individual fluorescing components, as well as beta-carotene concentration, hemoglobin saturation, and the mean reduced scattering coefficient display statistically significant differences between malignant and adipose breast tissues. The hemoglobin saturation and the reduced scattering coefficient display statistically significant differences between malignant and fibrous/benign breast tissues. A linear support vector machine classification using (1) fluorescence properties alone, (2) absorption and scattering properties alone, and (3) the combination of all tissue properties achieves comparable classification accuracies of 81 to 84% in sensitivity and 75 to 89% in specificity for discriminating malignant from nonmalignant breast tissues, suggesting each set of tissue properties are diagnostically useful for the discrimination of breast malignancy.
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Affiliation(s)
- Changfang Zhu
- University of Wisconsin-Madison, Department of Electrical and Computer Engineering, Madison, Wisconsin 53705, USA.
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1833
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Abstract
The objective of this study was to investigate the electrical impedance properties of rat lung and other tissues ex vivo using Electrical Impedance Spectroscopy. Rat lungs (both electroporated and naïve (untreated)), and mesenteric vessels (naïve) were harvested from male Sprague-Dawley rats; their electrical impedance were measured using a Solartron 1290 impedance analyzer. Mouse lung and heart samples (naïve) were also studied. The resistance (Real Z, ohm) and the reactance (Im Z, negative ohm)) magnitudes and hence the Cole-Cole (Real Z versus Im Z) plots are different for the electroporated lung and the naive lung. The results confirm the close relationship between the structure and the functional characteristic. These also vary for the different biological tissues studied. The impedance values were higher at low frequencies compared to those at high frequencies. This study is of practical interest for biological applications of electrical pulses, such as electroporation, whose efficacy depends on cell type and its electrical impedance characteristics.
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Affiliation(s)
- D.A. Dean
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - T. Ramanathan
- Mechanical Engineering Dept., Northwestern University, Evanston, IL-60208, e-mail:
| | - D. Machado
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - R. Sundararajan
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
- Electronics & Computer Engineering Technology, Arizona State University, Mesa, AZ-85212
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1834
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Ahl S, Cameron PJ, Liu J, Knoll W, Erlebacher J, Yu F. A Comparative Plasmonic Study of Nanoporous and Evaporated Gold Films. Plasmonics 2008; 3:13-20. [PMID: 19816537 PMCID: PMC2758361 DOI: 10.1007/s11468-007-9048-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 11/14/2007] [Indexed: 05/20/2023]
Abstract
Previously, we have reported that nanoporous gold (NPG) films prepared by a chemical dealloying method have distinctive plasmonic properties, i.e., they can simultaneously support localized and propagating surface plasmon resonance modes (l-SPR and p-SPR, respectively). In this study, the plasmonic properties of NPG are quantified through direct comparison with thermally evaporated gold (EG) films. Cyclic voltammetry and electrochemical impedance spectroscopy experiments reveal that the NPG films have 4-8.5 times more accessible surface area than EG films. Assemblies of streptavidin-latex beads generate p-SPR responses on both NPG and EG films that correlate well with the bead density obtained from scanning electron microscopy (SEM) images. A layer-by-layer assembly experiment on NPG involving biotinylated anti-avidin IgG and avidin, studied by l-SPR and SEM, shows that the l-SPR signal is directly linked to the accessibility of the interior of the NPG porosity, an adjustable experimental parameter that can be set by the dealloying condition and time. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11468-007-9048-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stefanie Ahl
- Department of Materials Science, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Petra J. Cameron
- Department of Materials Science, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department of Chemistry, University of Bath, Bath, BA2 2TB UK
| | - Jing Liu
- Department of Materials Science, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Siemens X-Ray Vacuum Technology Ltd., Wuxi, 214028 People’s Republic of China
| | - Wolfgang Knoll
- Department of Materials Science, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jonah Erlebacher
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Fang Yu
- Department of Materials Science, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department of Chemistry, Stanford University, Stanford, CA 94305 USA
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1835
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Michalet X, Cheng A, Antelman J, Suyama M, Arisaka K, Weiss S. Hybrid photodetector for single-molecule spectroscopy and microscopy. Proc SPIE Int Soc Opt Eng 2008; 6862:68620F_1. [PMID: 21822361 PMCID: PMC3150536 DOI: 10.1117/12.763449] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We report benchmark tests of a new single-photon counting detector based on a GaAsP photocathode and an electron-bombarded avalanche photodiode developed by Hamamatsu Photonics. We compare its performance with those of standard Geiger-mode avalanche photodiodes. We show its advantages for FCS due to the absence of after-pulsing and for fluorescence lifetime measurements due to its excellent time resolution. Its large sensitive area also greatly simplifies setup alignment. Its spectral sensitivity being similar to that of recently introduced CMOS SPADs, this new detector could become a valuable tool for single-molecule fluorescence measurements, as well as for many other applications.
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Affiliation(s)
- X. Michalet
- Dept. of Chemistry & Biochemistry, University of California at Los Angeles, 607 Charles E Young Drive E, Los Angeles, CA 90095
| | - Adrian Cheng
- Dept. of Physics & Astronomy, University of California at Los Angeles, 405 Hilgard Ave, Los Angeles, CA 90095
| | - Joshua Antelman
- Dept. of Chemistry & Biochemistry, University of California at Los Angeles, 607 Charles E Young Drive E, Los Angeles, CA 90095
| | - Motohiro Suyama
- Electron Tube Division, Hamamatsu Photonics K.K., 315-5 Toyooka village, Iwata-gun 438-0193, Japan
| | - Katsushi Arisaka
- Dept. of Physics & Astronomy, University of California at Los Angeles, 405 Hilgard Ave, Los Angeles, CA 90095
| | - Shimon Weiss
- Dept. of Chemistry & Biochemistry, University of California at Los Angeles, 607 Charles E Young Drive E, Los Angeles, CA 90095
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1836
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Chang L, Friedman J, Ernst T, Zhong K, Tsopelas ND, Davis K. Brain metabolite abnormalities in the white matter of elderly schizophrenic subjects: implication for glial dysfunction. Biol Psychiatry 2007; 62:1396-404. [PMID: 17693392 PMCID: PMC2222890 DOI: 10.1016/j.biopsych.2007.05.025] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 05/09/2007] [Accepted: 05/10/2007] [Indexed: 01/08/2023]
Abstract
BACKGROUND Abnormalities in the white matter of the brain may occur in individuals with schizophrenia as well as with normal aging. Therefore, elderly schizophrenic patients may suffer further cognitive decline as they age. This study determined whether elderly schizophrenia participants, especially those with declined cognitive function (Clinical Dementia Rating score > 1), show white matter metabolite abnormalities on proton magnetic resonance spectroscopy and whether there are group differences in age-dependent changes in these brain metabolites. METHOD Twenty-three elderly schizophrenia and twenty-two comparison participants fulfilling study criteria were enrolled. Localized, short echo-time (1)H MRS at 4 Tesla was used to assess neurometabolite concentrations in several white matter regions. RESULTS Compared with healthy subjects, schizophrenia participants had lower N-acetyl compounds (-12.6%, p = .0008), lower myo-inositol (-16.4%, p = .026), and higher glutamate + glutamine (+28.7%, p = .0016) concentrations across brain regions. Schizophrenia participants with Clinical Dementia Rating >/= 1 showed the lowest NA in the frontal and temporal regions compared with control subjects. Interactions between age and schizophrenia status on total creatine and choline-containing compounds were observed; only schizophrenia participants showed age-related decreases of these metabolites in the right frontal region. CONCLUSIONS Decreased NA in these white matter brain regions likely reflects reduced neuronal content associated with decreased synapses and neuronal cell volumes. The elevated glutamate + glutamine, if reflecting elevated glutamate, could result from excess neuronal glutamate release or glial dysfunction in glutamate reuptake. The decreased myo-inositol in participants with schizophrenia suggests decreased glial content or dysfunctional glia, which might result from glutamate-mediated toxicity.
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Affiliation(s)
- Linda Chang
- Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii 96813, USA.
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1837
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Buck J, Fürtig B, Noeske J, Wöhnert J, Schwalbe H. Time-resolved NMR methods resolving ligand-induced RNA folding at atomic resolution. Proc Natl Acad Sci U S A 2007; 104:15699-704. [PMID: 17895388 PMCID: PMC2000436 DOI: 10.1073/pnas.0703182104] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Indexed: 12/16/2022] Open
Abstract
Structural transitions of RNA between alternate conformations with similar stabilities are associated with important aspects of cellular function. Few techniques presently exist that are capable of monitoring such transitions and thereby provide insight into RNA dynamics and function at atomic resolution. Riboswitches are found in the 5'-UTR of mRNA and control gene expression through structural transitions after ligand recognition. A time-resolved NMR strategy was established in conjunction with laser-triggered release of the ligand from a photocaged derivative in situ to monitor the hypoxanthine-induced folding of the guanine-sensing riboswitch aptamer domain of the Bacillus subtilis xpt-pbuX operon at atomic resolution. Combining selective isotope labeling of the RNA with NMR filter techniques resulted in significant spectral resolution and allowed kinetic analysis of the buildup rates for individual nucleotides in real time. Three distinct kinetic steps associated with the ligand-induced folding were delineated. After initial complex encounter the ligand-binding pocket is formed and results in subsequent stabilization of a remote long-range loop-loop interaction. Incorporation of NMR data into experimentally restrained molecular dynamics simulations provided insight into the RNA structural ensembles involved during the conformational transition.
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Affiliation(s)
- Janina Buck
- *Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany; and
| | - Boris Fürtig
- *Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany; and
| | - Jonas Noeske
- *Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany; and
- Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229
| | - Jens Wöhnert
- *Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany; and
- Department of Biochemistry, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229
| | - Harald Schwalbe
- *Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Max von Laue-Strasse 7, 60438 Frankfurt am Main, Germany; and
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1838
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Abstract
INTRODUCTION Peripheral arterial disease (PAD) is characterized by lower limb arterial obstruction due to atherosclerosis and is increasingly common. Presently used methods for diagnosis and follow-up as well as for assessment of novel therapies are limited. MATERIALS AND METHODS Three distinct magnetic resonance examinations were developed. The first was high-resolution black-blood atherosclerotic plaque imaging of the superficial femoral artery using a surface coil and flow saturation. Second, first-pass contrast-enhanced dual-contrast perfusion imaging of the calf muscle was performed at peak exercise using a magnetic resonance (MR)-compatible pedal ergometer. Lastly, (31)P MR spectroscopy was also performed at peak exercise to measure phosphocreatine (PCr) recovery kinetics. RESULTS Seventeen patients (age, 63 +/- 10 yrs) with mild to moderate PAD were studied with black-blood atherosclerotic plaque imaging. Mean atherosclerotic plaque volume measured was 7.27 +/- 3.73 cm(3). Eleven patients (age, 61 +/- 11 yrs) with mild to moderate symptomatic PAD and 22 normal control subjects were studied with first-pass contrast-enhanced perfusion imaging. Perfusion index was stepwise increased from patients to normal subjects with matched workload to normal subjects at maximal exercise. For PCr recovery kinetics, 20 patients with mild to moderate PAD and 14 controls were studied. The median recovery time constant of PCr was 34.7 seconds in the controls and 91.0 seconds in the PAD patients (P < 0.0001). CONCLUSIONS Three distinct MR examinations of different aspects of peripheral arterial disease have been developed and tested and shown to differentiate patients with mild to moderate PAD from normal controls. Taken together, these tests are potential quantitative end points for clinical trials of novel therapies in PAD.
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Affiliation(s)
- Christopher M Kramer
- Department of Radiology, University of Virginia Health System, Charlottesville, VA 22908, USA.
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1839
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Topal G, Tümerdem R, Basaran I, Gümüş A, Cakir U. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations. Int J Mol Sci 2007. [PMCID: PMC3871894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The constants of the extraction equilibrium and the distribution for dichloromethane as an organic solvent having low dielectric constant of metal cations with chiral Schiff bases, benzaldehydene-(S)-2-amino-3-phenylpropanol (I), ohydroxybenzaldehydene-( S)-2-amino-3-phenyl-propanol (II), benzaldehydene-(S)-2- amino-3-methylbutanol (III) with anionic dyes [4-(2-pyridylazo)-resorcinol mono sodium monohydrate (NaPar), sodium picrat (NaPic) and potassium picrat (KPic)] and some heavy metal chlorides were determined at 25 ºC. All the ligands have given strongest complexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is not apparent in the complexation of corresponding ligands.
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Affiliation(s)
- Giray Topal
- Dicle University, Faculty of Education, Department of Chemistry, 21280, Diyarbakir, Turkey
| | - Recep Tümerdem
- Dicle University, Faculty of Education, Department of Chemistry, 21280, Diyarbakir, Turkey
| | - Ismet Basaran
- Balikesir University, Faculty of Science and Art, Department of Chemistry, 10145, Balikesir, Turkey
| | - Arzu Gümüş
- Balikesir University, Faculty of Science and Art, Department of Chemistry, 10145, Balikesir, Turkey
| | - Umit Cakir
- Balikesir University, Faculty of Science and Art, Department of Chemistry, 10145, Balikesir, Turkey,Author to whom correspondence should be addressed; E-mail:
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1840
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Cowan RL, Bolo NR, Dietrich M, Haga E, Lukas SE, Renshaw PF. Occipital cortical proton MRS at 4 Tesla in human moderate MDMA polydrug users. Psychiatry Res 2007; 155:179-88. [PMID: 17574394 PMCID: PMC2132656 DOI: 10.1016/j.pscychresns.2007.01.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 01/09/2007] [Accepted: 01/28/2007] [Indexed: 10/23/2022]
Abstract
The recreational drug MDMA (3,4, methylenedioxymethamphetamine; sold under the street name of Ecstasy) is toxic to serotonergic axons in some animal models of MDMA administration. In humans, MDMA use is associated with alterations in markers of brain function that are pronounced in occipital cortex. Among neuroimaging methods, magnetic resonance spectroscopy (MRS) studies of brain metabolites N-acetylaspartate (NAA) and myoinositol (MI) at a field strength of 1.5 Tesla (T) reveal inconsistent results in MDMA users. Because higher field strength proton MRS has theoretical advantages over lower field strengths, we used proton MRS at 4.0 T to study absolute concentrations of occipital cortical NAA and MI in a cohort of moderate MDMA users (n=9) versus non-MDMA using (n=7) controls. Mean NAA in non-MDMA users was 10.47 mM (+/-2.51), versus 9.83 mM (+/-1.94) in MDMA users. Mean MI in non-MDMA users was 7.43 mM (+/-.68), versus 6.57 mM (+/-1.59) in MDMA users. There were no statistical differences in absolute metabolite levels for NAA and MI in occipital cortex of MDMA users and controls. These findings are not supportive of MDMA-induced alterations in NAA or MI levels in this small sample of moderate MDMA users. Limitations to this study suggest caution in the interpretation of these results.
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Affiliation(s)
- Ronald L Cowan
- Psychiatric Neuroimaging Program, Department of Psychiatry, Vanderbilt University Medical Center, 1601 23rd Avenue South, Suite 3057, Nashville, TN 37212, USA.
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1841
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Kagemann L, Wollstein G, Wojtkowski M, Ishikawa H, Townsend KA, Gabriele ML, Srinivasan VJ, Fujimoto JG, Schuman JS. Spectral oximetry assessed with high-speed ultra-high-resolution optical coherence tomography. J Biomed Opt 2007; 12:041212. [PMID: 17867801 PMCID: PMC2916162 DOI: 10.1117/1.2772655] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We use Fourier domain optical coherence tomography (OCT) data to assess retinal blood oxygen saturation. Three-dimensional disk-centered retinal tissue volumes were assessed in 17 normal healthy subjects. After removing DC and low-frequency a-scan components, an OCT fundus image was created by integrating total reflectance into a single reflectance value. Thirty fringe patterns were sampled; 10 each from the edge of an artery, adjacent tissue, and the edge of a vein, respectively. A-scans were recalculated, zeroing the DC term in the power spectrum, and used for analysis. Optical density ratios (ODRs) were calculated as ODR(Art)=ln(Tissue(855)Art(855))ln(Tissue(805)Art(805)) and ODR(Vein)=ln(Tissue(855)Vein(855))ln(Tissue(805)Vein(805)) with Tissue, Art, and Vein representing total a-scan reflectance at the 805- or 855-nm centered bandwidth. Arterial and venous ODRs were compared by the Wilcoxon signed rank test. Arterial ODRs were significantly greater than venous ODRs (1.007+/-2.611 and -1.434+/-4.310, respectively; p=0.0217) (mean+/-standard deviation). A difference between arterial and venous blood saturation was detected. This suggests that retinal oximetry may possibly be added as a metabolic measurement in structural imaging devices.
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Affiliation(s)
- Larry Kagemann
- University of Pittsburgh School of Medicine, Department of Ophthalmology, Ophthalmology and Visual Sciences Research Center, UPMC Eye Center, Eye and Ear Institute, Pittsburgh, Pennsylvania 15213, USA
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1842
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Rosenthal SJ, McBride J, Pennycook SJ, Feldman LC. Synthesis, Surface Studies, Composition and Structural Characterization of CdSe, Core/Shell, and Biologically Active Nanocrystals. Surf Sci Rep 2007; 62:111-157. [PMID: 21479151 PMCID: PMC3071516 DOI: 10.1016/j.surfrep.2007.02.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nanostructures, with their very large surface to volume ratio and their non-planar geometry, present an important challenge to surface scientists. New issues arise as to surface characterization, quantification and interface formation. This review summarizes the current state of the art in the synthesis, composition, surface and interface control of CdSe nanocrystal systems, one of the most studied and useful nanostructures.
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Affiliation(s)
- Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN
| | - James McBride
- Department of Chemistry, Vanderbilt University, Nashville, TN
| | - Stephen J. Pennycook
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN
| | - Leonard C. Feldman
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN
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1843
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Sampath-Wiley P, Neefus CD. An improved method for estimating R-phycoerythrin and R-phycocyanin contents from crude aqueous extracts of Porphyra (Bangiales, Rhodophyta). J Appl Phycol 2007; 19:123-129. [PMID: 19396349 PMCID: PMC2668582 DOI: 10.1007/s10811-006-9118-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 06/13/2006] [Indexed: 05/22/2023]
Abstract
One frequently-cited method for determining phycoerythrin (PE) and phycocyanin (PC) contents from crude aqueous extracts of red seaweeds utilizes peaks and troughs of absorbance spectra. The trough absorbance values are used to establish a linear or logarithmic baseline attributable to background scatter of particulate cellular debris not removed by centrifugation. Pigment contents are calculated by subtracting baseline values from PE and PC absorbance peaks. The baseline correction is intended to make the method independent of centrifugation time and/or speed. However, when crude extracts of Porphyra were analyzed using this protocol, R-PE and R-PC estimates were significantly affected by centrifugation time, suggesting that the method was not reliable for the genus. The present study has shown that with sufficient centrifugation, background scatter in Porphyra extracts can be removed, the remaining spectrum representing the overlapping absorbance peaks of water-soluble pigments in the extract. Using fourth derivative analysis of Porphyra extract absorbance spectra, peaks corresponding to chlorophyll, R-PE, R-PC, and allophycocyanin (APC) were identified. Dilute solutions of purified R-PE, R-PC and chlorophyll were scanned separately to identify spectral overlaps and develop new equations for phycobilin quantification. The new equations were used to estimate R-PE and R-PC contents of Porphyra extracts and purified R-PE, R-PC and chlorophyll solutions were mixed according to concentrations corresponding to the sample estimates. Absorbances and fourth derivative spectra of the sample extract and purified pigment mixtures were compared and found to coincide. The newly derived equations are more accurate for determining R-PE and R-PC of Porphyra than previously published methods.
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Affiliation(s)
- Priya Sampath-Wiley
- University of New Hampshire, Department of Plant Biology, Durham, NH 03824 USA
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1844
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Finlay JC, Zhu TC, Zhou X, Dimofte A, Malkowicz SB, Hahn SM. A method to improve reconstruction of the distribution of hemoglobin, oxygenation, and MLu concentration in the human prostate before and after photodynamic therapy. Proc SPIE Int Soc Opt Eng 2007; 6427:64270K. [PMID: 26136614 PMCID: PMC4484876 DOI: 10.1117/12.699545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Explicit dosimetry of photodynamic therapy requires detailed knowledge of the light, drug, and oxygenation distributions within the target tissue. We present a method for the optical detection and three-dimensional reconstruction of hemoglobin concentration and oxygenation and sensitizer concentration within the human prostate. Spectrally resolved diffuse transmission measurements were made using a small isotropic fiber-based white light source and an isotropic detector inserted into the prostate via parallel closed transparent catheters. The spectra were modeled using the diffusion approximation appropriate for infinite media. The optical absorption of the prostate was assumed to be a linear combination of the absorption spectra of oxy- and deoxyhemoglobin and MLu, and the scattering was assumed to be of the form A(λ/λ0)-b. The separation of absorption and scattering coefficients was accomplished based on the spectral shape of the diffuse transmission, rather than the spatial variation in intensity. By making multiple measurements at various source-detector separations, we investigate the signal-to-noise sensitivity of our algorithm. In addition, the redundancy in our source-detector position matrix creates several positions in which the tissue parameters can be reconstructed from multiple independent measurements, allowing an assessment of the repeatability of the algorithm. We find significant heterogeneity in the reconstructed optical properties; however the recovery of spectrally consistent absorption and scattering spectra is improved compared to wavelength-wise reconstruction algorithms.
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Affiliation(s)
- Jarod C Finlay
- Department of Radiation Oncology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
| | - Timothy C Zhu
- Department of Radiation Oncology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
| | - Xiaodong Zhou
- Department of Radiation Oncology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
| | - Andreea Dimofte
- Department of Radiation Oncology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
| | - S B Malkowicz
- Department of Urology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
| | - Stephen M Hahn
- Department of Radiation Oncology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA USA 19104
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1845
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Michalet X, Siegmund OHW, Vallerga JV, Jelinsky P, Millaud JE, Weiss S. Detectors for single-molecule fluorescence imaging and spectroscopy. J Mod Opt 2007; 54:239. [PMID: 20157633 PMCID: PMC2821066 DOI: 10.1080/09500340600769067] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Single-molecule observation, characterization and manipulation techniques have recently come to the forefront of several research domains spanning chemistry, biology and physics. Due to the exquisite sensitivity, specificity, and unmasking of ensemble averaging, single-molecule fluorescence imaging and spectroscopy have become, in a short period of time, important tools in cell biology, biochemistry and biophysics. These methods led to new ways of thinking about biological processes such as viral infection, receptor diffusion and oligomerization, cellular signaling, protein-protein or protein-nucleic acid interactions, and molecular machines. Such achievements require a combination of several factors to be met, among which detector sensitivity and bandwidth are crucial. We examine here the needed performance of photodetectors used in these types of experiments, the current state of the art for different categories of detectors, and actual and future developments of single-photon counting detectors for single-molecule imaging and spectroscopy.
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Affiliation(s)
- X Michalet
- Department of Chemistry & Biochemistry, University of California at Los Angeles, 607 Charles E. Young Drive E., Los Angeles, CA 90095, USA
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1846
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Abstract
A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated (252)Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements.
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1847
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Abstract
Neurodegeneration refers to a large clinically and pathologically heterogeneous disease entity associated with slowly progressive neuronal loss in different anatomical and functional systems of the brain. Neurodegenerative diseases often affect cognition, e.g. Alzheimer's disease (AD), dementia with Lewy bodies and vascular dementia, or different aspects of the motor system, e.g., amyotrophic lateral sclerosis, Parkinson's disease and ataxic disorders. Owing to increasing knowledge about the mechanisms leading to neurodegeneration, the development of treatments able to modify the neurodegenerative process becomes possible for the first time. Currently, clinical outcome measures are used to assess the efficacy of such treatments. However, most clinical outcome measures have a low test-retest reliability and thus considerable measurement variance. Therefore, large patient populations and long observation times are needed to detect treatment effects. Furthermore, clinical outcome measures cannot distinguish between symptomatic and disease-modifying treatment effects. Therefore, alternative biomarkers including neuroimaging may take on a more important role in this process. Because MR scanners are widely available and allow for non-invasive detection and quantification of changes in brain structure and metabolism, there is increasing interest in the use of MRI/MRS to monitor objectively treatment effects in clinical trials of neurodegenerative diseases. Particularly volumetric MRI has been used to measure atrophy rates in treatment trials of AD because the relationship between atrophic changes and neuron loss is well established and correlates well with clinical measures. More research is needed to determine the value of other MR modalities, i.e. diffusion, perfusion and functional MRI and MR spectroscopy, for clinical trials with neuroprotective drugs.
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Affiliation(s)
- S. G. Mueller
- Center of Imaging of Neurodegenerative Diseases, Veterans Administration Medical Center, Department of Radiology, University of California San Francisco, San Francisco, CA 94121, USA
| | - N. Schuff
- Center of Imaging of Neurodegenerative Diseases, Veterans Administration Medical Center, Department of Radiology, University of California San Francisco, San Francisco, CA 94121, USA
| | - M. W. Weiner
- Center of Imaging of Neurodegenerative Diseases, Veterans Administration Medical Center, Department of Radiology, University of California San Francisco, San Francisco, CA 94121, USA
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1848
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Wagner NL, Wüest A, Christov IP, Popmintchev T, Zhou X, Murnane MM, Kapteyn HC. Monitoring molecular dynamics using coherent electrons from high harmonic generation. Proc Natl Acad Sci U S A 2006; 103:13279-85. [PMID: 16895984 PMCID: PMC1533881 DOI: 10.1073/pnas.0605178103] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report a previously undescribed spectroscopic probe that makes use of electrons rescattered during the process of high-order harmonic generation. We excite coherent vibrations in SF(6) using impulsive stimulated Raman scattering with a short laser pulse. A second, more intense laser pulse generates high-order harmonics of the fundamental laser, at wavelengths of approximately 20-50 nm. The high-order harmonic yield is observed to oscillate, at frequencies corresponding to all of the Raman-active modes of SF(6), with an asymmetric mode most visible. The data also show evidence of relaxation dynamics after impulsive excitation of the molecule. Theoretical modeling indicates that the high harmonic yield should be modulated by both Raman and infrared-active vibrational modes. Our results indicate that high harmonic generation is a very sensitive probe of vibrational dynamics and may yield more information simultaneously than conventional ultrafast spectroscopic techniques. Because the de Broglie wavelength of the recolliding electron is on the order of interatomic distances, i.e., approximately 1.5 A, small changes in the shape of the molecule lead to large changes in the high harmonic yield. This work therefore demonstrates a previously undescribed spectroscopic technique for probing ultrafast internal dynamics in molecules and, in particular, on the chemically important ground-state potential surface.
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Affiliation(s)
- Nicholas L. Wagner
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Andrea Wüest
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Ivan P. Christov
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Tenio Popmintchev
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Xibin Zhou
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Margaret M. Murnane
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
| | - Henry C. Kapteyn
- Department of Physics, JILA, and National Science Foundation Engineering Research Center in Extreme-Ultraviolet Science and Technology, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440
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1849
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Lovat LB, Johnson K, Mackenzie GD, Clark BR, Novelli MR, Davies S, O'Donovan M, Selvasekar C, Thorpe SM, Pickard D, Fitzgerald R, Fearn T, Bigio I, Bown SG. Elastic scattering spectroscopy accurately detects high grade dysplasia and cancer in Barrett's oesophagus. Gut 2006; 55:1078-83. [PMID: 16469795 PMCID: PMC1856278 DOI: 10.1136/gut.2005.081497] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND AIMS Endoscopic surveillance of Barrett's oesophagus currently relies on multiple random biopsies. This approach is time consuming, has a poor diagnostic yield, and significant interobserver variability. Elastic scattering spectroscopy is a real time in vivo optical technique which detects changes in the physical properties of cells. The aim of this study was to assess the potential for elastic scattering to detect high grade dysplasia or cancer within Barrett's oesophagus. METHODS Elastic scattering spectroscopy measurements collected in vivo were matched with histological specimens taken from identical sites within Barrett's oesophagus. All biopsies were reviewed by three gastrointestinal pathologists and defined as either "low risk" (non-dysplastic or low grade dysplasia) or "high risk" (high grade dysplasia or cancer). Two different statistical approaches (leave one out and block validation) were used to validate the model. RESULTS A total of 181 matched biopsy sites from 81 patients, where histopathological consensus was reached, were analysed. There was good pathologist agreement in differentiating high grade dysplasia and cancer from other pathology (kappa = 0.72). Elastic scattering spectroscopy detected high risk sites with 92% sensitivity and 60% specificity and differentiated high risk sites from inflammation with a sensitivity and specificity of 79%. If used to target biopsies during endoscopy, the number of low risk biopsies taken would decrease by 60% with minimal loss of accuracy. A negative spectroscopy result would exclude high grade dysplasia or cancer with an accuracy of >99.5%. CONCLUSIONS These preliminary results show that elastic scattering spectroscopy has the potential to target conventional biopsies in Barrett's surveillance saving significant endoscopist and pathologist time with consequent financial savings. This technique now requires validation in prospective studies.
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Affiliation(s)
- L B Lovat
- National Medical Laser Centre, Department of Surgery, Royal Free and University College Medical School, University College London, UK.
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1850
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Abstract
Magnetic resonance imaging (MRI) plays an ever-expanding role in the evaluation of multiple sclerosis (MS). This includes its sensitivity for the diagnosis of the disease and its role in identifying patients at high risk for conversion to MS after a first presentation with selected clinically isolated syndromes. In addition, MRI is a key tool in providing primary therapeutic outcome measures for phase I/II trials and secondary outcome measures in phase III trials. The utility of MRI stems from its sensitivity to longitudinal changes including those in overt lesions and, with advanced MRI techniques, in areas affected by diffuse occult disease (the so-called normal-appearing brain tissue). However, all current MRI methodology suffers from limited specificity for the underlying histopathology. Conventional MRI techniques, including lesion detection and measurement of atrophy from T1- or T2-weighted images, have been the mainstay for monitoring disease activity in clinical trials, in which the use of gadolinium with T1-weighted images adds additional sensitivity and specificity for areas of acute inflammation. Advanced imaging methods including magnetization transfer, fluid attenuated inversion recovery, diffusion, magnetic resonance spectroscopy, functional MRI, and nuclear imaging techniques have added to our understanding of the pathogenesis of MS and may provide methods to monitor therapies more sensitively in the future. However, these advanced methods are limited by their cost, availability, complexity, and lack of validation. In this article, we review the role of conventional and advanced imaging techniques with an emphasis on neurotherapeutics.
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Affiliation(s)
- Rohit Bakshi
- Department of Neurology and Radiology, Partners MS Center, Center for Neurological Imaging, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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