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Cooper JM, Lathuiliere A, Su EJ, Song Y, Torrente D, Jo Y, Weinrich N, Sales JD, Migliorini M, Sisson TH, Lawrence DA, Hyman BT, Strickland DK. SORL1 is a receptor for tau that promotes tau seeding. J Biol Chem 2024:107313. [PMID: 38657864 DOI: 10.1016/j.jbc.2024.107313] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/28/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
Sortilin-related receptor 1 (SORL1) is an intracellular sorting receptor genetically implicated in Alzheimer's disease (AD) that impacts amyloid precursor protein trafficking. The objective of these studies was to test the hypothesis that SORL1 binds tau, modulates its cellular trafficking and impacts the aggregation of cytoplasmic tau induced by pathological forms of tau. Using surface plasmon resonance measurements, we observed high-affinity binding of tau to SORL1 and the vacuolar protein sorting 10 (VPS10) domain of SORL1. Interestingly, unlike LRP1, SORL1 binds tau at both pH 7.4 and pH 5.5, revealing its ability to bind tau at endosomal pH. Immunofluorescence studies confirmed that exogenously added tau colocalized with SORL1 in H4 neuroglioma cells, while overexpression of SORL1 in LRP1-deficient Chinese hamster ovary (CHO) cells resulted in a marked increase in the internalization of tau, indicating that SORL1 can bind and mediate the internalization of monomeric forms of tau. We further demonstrated that SORL1 mediates tau seeding when tau RD P301S FRET biosensor cells expressing SORL1 were incubated with high molecular weight forms of tau isolated from the brains of patients with AD. Seeding in H4 neuroglioma cells is significantly reduced when SORL1 is knocked down with siRNA. Finally, we demonstrate that the N1358S mutant of SORL1 significantly increases tau seeding when compared to WT SORL1, identifying for the first time a potential mechanism that connects this specific SORL1 mutation to Alzheimer's disease. Together, these studies identify SORL1 as a receptor that contributes to trafficking and seeding of pathogenic tau.
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Affiliation(s)
- Joanna M Cooper
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Aurelien Lathuiliere
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA; Memory Center, Department of Rehabilitation and Geriatrics, Geneva University Hospital and University of Geneva, Geneva, Switzerland
| | - Enming J Su
- Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI
| | - Yuyu Song
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA
| | - Daniel Torrente
- Patricia and John Rosenwald Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY
| | - Youhwa Jo
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA
| | - Nicholas Weinrich
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Jennifer Diaz Sales
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Mary Migliorini
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Thomas H Sisson
- Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI
| | - Daniel A Lawrence
- Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI
| | - Bradley T Hyman
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA.
| | - Dudley K Strickland
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201; Departments of Physiology and University of Maryland School of Medicine, Baltimore, MD 21201; Departments of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201.
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Cooper JM, Lathuiliere A, Dickson J, Glynn C, Fan Z, Donahue C, Migliorini M, Hyman BT, Strickland DK. Investigating the binding of high molecular weight tau to LRP1. Alzheimers Dement 2022. [DOI: 10.1002/alz.069020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | | | | | - Zhanyun Fan
- Massachusetts General Hospital, Harvard Medical School Charlestown MA USA
| | | | | | - Bradley T. Hyman
- Massachusetts General Hospital Boston MA USA
- Harvard Medical School Boston MA USA
- Massachusetts Alzheimer’s Disease Research Center Charlestown MA USA
- Massachusetts General Hospital, Harvard Medical School Boston MA USA
- Massachusetts General Hospital Charlestown MA USA
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3
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Cooper JM, Lathuiliere A, Migliorini M, Arai AL, Wani MM, Dujardin S, Muratoglu SC, Hyman BT, Strickland DK. Regulation of tau internalization, degradation, and seeding by LRP1 reveals multiple pathways for tau catabolism. J Biol Chem 2021; 296:100715. [PMID: 33930462 PMCID: PMC8164048 DOI: 10.1016/j.jbc.2021.100715] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 12/16/2022] Open
Abstract
In Alzheimer's disease (AD), pathological forms of tau are transferred from cell to cell and “seed” aggregation of cytoplasmic tau. Phosphorylation of tau plays a key role in neurodegenerative tauopathies. In addition, apolipoprotein E (apoE), a major component of lipoproteins in the brain, is a genetic risk determinant for AD. The identification of the apoE receptor, low-density lipoprotein receptor–related protein 1 (LRP1), as an endocytic receptor for tau raises several questions about the role of LRP1 in tauopathies: is internalized tau, like other LRP1 ligands, delivered to lysosomes for degradation, and does LRP1 internalize pathological tau leading to cytosolic seeding? We found that LRP1 rapidly internalizes 125I-labeled tau, which is then efficiently degraded in lysosomal compartments. Surface plasmon resonance experiments confirm high affinity binding of tau and the tau microtubule-binding domain to LRP1. Interestingly, phosphorylated forms of recombinant tau bind weakly to LRP1 and are less efficiently internalized by LRP1. LRP1-mediated uptake of tau is inhibited by apoE, with the apoE4 isoform being the most potent inhibitor, likely because of its higher affinity for LRP1. Employing post-translationally–modified tau derived from brain lysates of human AD brain tissue, we found that LRP1-expressing cells, but not LRP1-deficient cells, promote cytosolic tau seeding in a process enhanced by apoE. These studies identify LRP1 as an endocytic receptor that binds and processes monomeric forms of tau leading to its degradation and promotes seeding by pathological forms of tau. The balance of these processes may be fundamental to the spread of neuropathology across the brain in AD.
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Affiliation(s)
- Joanna M Cooper
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Aurelien Lathuiliere
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| | - Mary Migliorini
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Allison L Arai
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Mashhood M Wani
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Simon Dujardin
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| | - Selen C Muratoglu
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bradley T Hyman
- Alzheimer Research Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA.
| | - Dudley K Strickland
- The Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA.
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Cooper JM, Migliorini M, Arai AL, Muratoglu SC, Hyman BT, Strickland DK. LRP1 mediates tau endocytosis in a process that is modulated by apolipoprotein E. Alzheimers Dement 2020. [DOI: 10.1002/alz.045959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Futyma PR, Aksu T, Cooper JM, Schaller R, Winterfield J, Payne J, Omarov M, Vazquez O, Guler TE, Bozyel S, Zahwe F, Gautam S, Futyma M, Vijayaraman P, Kulakowski P. P1127Occurrence, management and outcomes of iatrogenic aortic dissections as a complication of catheter ablation. A multicenter study. Europace 2020. [DOI: 10.1093/europace/euaa162.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Data on occurrence, management and outcomes of iatrogenic aortic dissections (IAD) as a complication of catheter ablation (CA) do not exist.
Purpose
To evaluate multicenter data on occurrence, management and outcomes of IAD as a complication of CA.
Methods
Data on occurrence, management and outcomes of documented vascular dissections from 10 centers were evaluated.
Results
IADs occurred in 7 patients (2 females, age 63 ± 8 years). Indications for CA were frequent premature ventricular complexes (PVC)/ventricular tachycardia (VT) in 6 patients (86%) and left-sided accessory pathway in the remaining one (14%). Hypertension was most frequent comorbidity (4 pts, 57%). All IADs occurred during retrograde advancement of ablation catheter. In the vast majority of patients creation of IAD during catheter advancement was not associated with any symptoms (6 pts, 86%). IAD was initially detected using trans-luminal angiogram in 5 (71%) and further confirmed using computed tomography (CT) (5 pts, 71%), conventional angiography (2 pts, 28%) and ultrasound (2 pts, 28%). One IAD was detected during CT scan performed for other indication after CA. There was one IAD-related death and IAD was evaluated post-mortem. Follow-up lasted 10 ± 19 months. Four patients were treated conservatively, one patient underwent descending aorta stenting and one femoral artery stenting.
Conclusions
IAD during CA is a rare but can be devastating. Early recognition can be difficult. Conservative management of IAD is an option of treatment.
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Affiliation(s)
- P R Futyma
- St. Joseph"s Heart Center, Invasive Cardiology Department, Rzeszów, Poland
| | - T Aksu
- Kocaeli Derince Hospital, Department of Cardiology, Kocaeli, Turkey
| | - J M Cooper
- Temple Heart & Vascular Institute, Cardiac Electrophysiology , Philadelphia, United States of America
| | - R Schaller
- University of Pennsylvania, Department of Cardiology, Philadelphia, United States of America
| | - J Winterfield
- Medical University of South Carolina, Division of Cardiology, Charleston, United States of America
| | - J Payne
- Medical University of South Carolina, Division of Cardiology, Charleston, United States of America
| | - M Omarov
- FCCVS, Department of Cardiology, Perm, Russian Federation
| | - O Vazquez
- Lic Adolfo López Mateos Hospital, ISSSTE, Mexico City, Mexico
| | - T E Guler
- Kocaeli Derince Hospital, Department of Cardiology, Kocaeli, Turkey
| | - S Bozyel
- Kocaeli Derince Hospital, Department of Cardiology, Kocaeli, Turkey
| | - F Zahwe
- Michigan Heart Rhythm Center, Dearborn, United States of America
| | - S Gautam
- University of Missouri, Division of Cardiovascular Medicine, Columbia, United States of America
| | - M Futyma
- St. Joseph"s Heart Center, Invasive Cardiology Department, Rzeszów, Poland
| | - P Vijayaraman
- Geisinger Heart Institute, Wilkes Barre, United States of America
| | - P Kulakowski
- Grochowski Hospital, Postgraduate Medical School, Warsaw, Poland
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Cooper JM, Halter KA, Prosser RA. Circadian rhythm and sleep-wake systems share the dynamic extracellular synaptic milieu. Neurobiol Sleep Circadian Rhythms 2018; 5:15-36. [PMID: 31236509 PMCID: PMC6584685 DOI: 10.1016/j.nbscr.2018.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/06/2018] [Accepted: 04/10/2018] [Indexed: 01/23/2023] Open
Abstract
The mammalian circadian and sleep-wake systems are closely aligned through their coordinated regulation of daily activity patterns. Although they differ in their anatomical organization and physiological processes, they utilize overlapping regulatory mechanisms that include an assortment of proteins and molecules interacting within the extracellular space. These extracellular factors include proteases that interact with soluble proteins, membrane-attached receptors and the extracellular matrix; and cell adhesion molecules that can form complex scaffolds connecting adjacent neurons, astrocytes and their respective intracellular cytoskeletal elements. Astrocytes also participate in the dynamic regulation of both systems through modulating neuronal appositions, the extracellular space and/or through release of gliotransmitters that can further contribute to the extracellular signaling processes. Together, these extracellular elements create a system that integrates rapid neurotransmitter signaling across longer time scales and thereby adjust neuronal signaling to reflect the daily fluctuations fundamental to both systems. Here we review what is known about these extracellular processes, focusing specifically on areas of overlap between the two systems. We also highlight questions that still need to be addressed. Although we know many of the extracellular players, far more research is needed to understand the mechanisms through which they modulate the circadian and sleep-wake systems.
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Key Words
- ADAM, A disintegrin and metalloproteinase
- AMPAR, AMPA receptor
- Astrocytes
- BDNF, brain-derived neurotrophic factor
- BMAL1, Brain and muscle Arnt-like-1 protein
- Bmal1, Brain and muscle Arnt-like-1 gene
- CAM, cell adhesion molecules
- CRY, cryptochrome protein
- Cell adhesion molecules
- Circadian rhythms
- Cry, cryptochrome gene
- DD, dark-dark
- ECM, extracellular matrix
- ECS, extracellular space
- EEG, electroencephalogram
- Endo N, endoneuraminidase N
- Extracellular proteases
- GFAP, glial fibrillary acidic protein
- IL, interleukin
- Ig, immunoglobulin
- LC, locus coeruleus
- LD, light-dark
- LH, lateral hypothalamus
- LRP-1, low density lipoprotein receptor-related protein 1
- LTP, long-term potentiation
- MMP, matrix metalloproteinases
- NCAM, neural cell adhesion molecule protein
- NMDAR, NMDA receptor
- NO, nitric oxide
- NST, nucleus of the solitary tract
- Ncam, neural cell adhesion molecule gene
- Nrl, neuroligin gene
- Nrx, neurexin gene
- P2, purine type 2 receptor
- PAI-1, plasminogen activator inhibitor-1
- PER, period protein
- PPT, peduculopontine tegmental nucleus
- PSA, polysialic acid
- Per, period gene
- REMS, rapid eye movement sleep
- RSD, REM sleep disruption
- SCN, suprachiasmatic nucleus
- SWS, slow wave sleep
- Sleep-wake system
- Suprachiasmatic nucleus
- TNF, tumor necrosis factor
- TTFL, transcriptional-translational negative feedback loop
- VIP, vasoactive intestinal polypeptide
- VLPO, ventrolateral preoptic
- VP, vasopressin
- VTA, ventral tegmental area
- dNlg4, drosophila neuroligin-4 gene
- nNOS, neuronal nitric oxide synthase gene
- nNOS, neuronal nitric oxide synthase protein
- tPA, tissue-type plasminogen activator
- uPA, urokinase-type plasminogen activator
- uPAR, uPA receptor
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Cooper JM, Rastogi A, Krizo JA, Mintz EM, Prosser RA. Urokinase-type plasminogen activator modulates mammalian circadian clock phase regulation in tissue-type plasminogen activator knockout mice. Eur J Neurosci 2017; 45:805-815. [PMID: 27992087 DOI: 10.1111/ejn.13511] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/20/2022]
Abstract
Glutamate phase shifts the circadian clock in the mammalian suprachiasmatic nucleus (SCN) by activating NMDA receptors. Tissue-type plasminogen activator (tPA) gates phase shifts by activating plasmin to generate m(ature) BDNF, which binds TrkB receptors allowing clock phase shifts. Here, we investigate phase shifting in tPA knockout (tPA-/- ; B6.129S2-Plattm1Mlg /J) mice, and identify urokinase-type plasminogen activator (uPA) as an additional circadian clock regulator. Behavioral activity rhythms in tPA-/- mice entrain to a light-dark (LD) cycle and phase shift in response to nocturnal light pulses with no apparent loss in sensitivity. When the LD cycle is inverted, tPA-/- mice take significantly longer to entrain than C57BL/6J wild-type (WT) mice. SCN brain slices from tPA-/- mice exhibit entrained neuronal activity rhythms and phase shift in response to nocturnal glutamate with no change in dose-dependency. Pre-treating slices with the tPA/uPA inhibitor, plasminogen activator inhibitor-1 (PAI-1), inhibits glutamate-induced phase delays in tPA-/- slices. Selective inhibition of uPA with UK122 prevents glutamate-induced phase resetting in tPA-/- but not WT SCN slices. tPA expression is higher at night than the day in WT SCN, while uPA expression remains constant in WT and tPA-/- slices. Casein-plasminogen zymography reveals that neither tPA nor uPA total proteolytic activity is under circadian control in WT or tPA-/- SCN. Finally, tPA-/- SCN tissue has lower mBDNF levels than WT tissue, while UK122 does not affect mBDNF levels in either strain. Together, these results suggest that either tPA or uPA can support photic/glutamatergic phase shifts of the SCN circadian clock, possibly acting through distinct mechanisms.
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Affiliation(s)
- Joanna M Cooper
- Department of Biochemistry and Cellular and Molecular Biology, NeuroNET Research Center, M407 Walters Life Sciences, University of Tennessee, Knoxville, TN, 37996-0001, USA
| | - Ashutosh Rastogi
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Jessica A Krizo
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Eric M Mintz
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Rebecca A Prosser
- Department of Biochemistry and Cellular and Molecular Biology, NeuroNET Research Center, M407 Walters Life Sciences, University of Tennessee, Knoxville, TN, 37996-0001, USA
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Rambach RW, Taiber J, Scheck CML, Meyer C, Reboud J, Cooper JM, Franke T. Visualization of Surface Acoustic Waves in Thin Liquid Films. Sci Rep 2016; 6:21980. [PMID: 26917490 PMCID: PMC4768107 DOI: 10.1038/srep21980] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/03/2016] [Indexed: 11/09/2022] Open
Abstract
We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect.
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Affiliation(s)
- R W Rambach
- Soft Matter Group, Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr, 1, D-86159 Augsburg, Germany
| | - J Taiber
- Soft Matter Group, Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr, 1, D-86159 Augsburg, Germany
| | - C M L Scheck
- Soft Matter Group, Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr, 1, D-86159 Augsburg, Germany
| | - C Meyer
- Soft Matter Group, Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr, 1, D-86159 Augsburg, Germany
| | - J Reboud
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, G12 8LT Glasgow, UK
| | - J M Cooper
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, G12 8LT Glasgow, UK
| | - T Franke
- Soft Matter Group, Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr, 1, D-86159 Augsburg, Germany.,Division of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, G12 8LT Glasgow, UK
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Macdonald NP, Zhu F, Hall CJ, Reboud J, Crosier PS, Patton EE, Wlodkowic D, Cooper JM. Assessment of biocompatibility of 3D printed photopolymers using zebrafish embryo toxicity assays. Lab Chip 2016; 16:291-7. [PMID: 26646354 PMCID: PMC4758231 DOI: 10.1039/c5lc01374g] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 11/20/2015] [Indexed: 05/04/2023]
Abstract
3D printing has emerged as a rapid and cost-efficient manufacturing technique to enable the fabrication of bespoke, complex prototypes. If the technology is to have a significant impact in biomedical applications, such as drug discovery and molecular diagnostics, the devices produced must be biologically compatible to enable their use with established reference assays and protocols. In this work we demonstrate that we can adapt the Fish Embryo Test (FET) as a new method to quantify the toxicity of 3D printed microfluidic devices. We assessed the biocompatibility of four commercially available 3D printing polymers (VisiJetCrystal EX200, Watershed 11122XC, Fototec SLA 7150 Clear and ABSplus P-430), through the observation of key developmental markers in the developing zebrafish embryos. Results show all of the photopolymers to be highly toxic to the embryos, resulting in fatality, although we do demonstrate that post-printing treatment of Fototec 7150 makes it suitable for zebrafish culture within the FET.
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Affiliation(s)
- N P Macdonald
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK.
| | - F Zhu
- The BioMEMS Research Group, School of Applied Sciences, RMIT University, Melbourne VIC 3083, Australia
| | - C J Hall
- Department of Molecular Medicine and Pathology, University of Auckland, Auckland 1023, New Zealand
| | - J Reboud
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK.
| | - P S Crosier
- Department of Molecular Medicine and Pathology, University of Auckland, Auckland 1023, New Zealand
| | - E E Patton
- MRC Institute of Genetics and Molecular Medicine, MRC Human Genetics Unit, Edinburgh, UK
| | - D Wlodkowic
- The BioMEMS Research Group, School of Applied Sciences, RMIT University, Melbourne VIC 3083, Australia
| | - J M Cooper
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK.
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Witte C, Reboud J, Wilson R, Cooper JM, Neale SL. Microfluidic resonant cavities enable acoustophoresis on a disposable superstrate. Lab Chip 2014; 14:4277-83. [PMID: 25224539 DOI: 10.1039/c4lc00749b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We demonstrate surface acoustic wave (SAW) induced microparticle manipulation in a microstructured disposable glass-polymer composite superstrate, positioned on a piezoelectric substrate with a single, slanted SAW transducer. An excited SAW was coupled from the piezoelectric substrate into the superstrate, which acted as a transversal resonator structure. We show that the energy transmitted into the superstrate allowed acoustophoretic particle manipulation, while the wide frequency response of the SAW transducer enabled tuneable pressure distributions confined by the microchannel layout. The configuration provides a significant tolerance in positioning - making assembly easy.
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Affiliation(s)
- C Witte
- Biomedical Engineering Research Division, School of Engineering, University of Glasgow, Glasgow, UK.
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11
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Paterson DJ, Reboud J, Wilson R, Tassieri M, Cooper JM. Integrating microfluidic generation, handling and analysis of biomimetic giant unilamellar vesicles. Lab Chip 2014; 14:1806-10. [PMID: 24789498 DOI: 10.1039/c4lc00199k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The key roles played by phospholipids in many cellular processes, has led to the development of model systems, to explore both lipid-lipid and lipid-peptide interactions. Biomimetic giant unilamellar vesicles represent close facsimiles of in vivo cellular membranes, although currently their widespread use in research is hindered by difficulties involving their integration into high-throughput techniques, for exploring membrane biology intensively in situ. This paper presents an integrated microfluidic device for the production, manipulation and high-throughput analysis of giant unilamellar vesicles. Its utility is demonstrated by exploring the lipid interaction dynamics of the pore-forming antimicrobial peptide melittin, assessed through the release of fluorescent dyes from within biomimetic vesicles, with membrane compositions similar to mammalian plasma membranes.
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Affiliation(s)
- D J Paterson
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Rankine Building, 78 Oakfield Avenue, Glasgow, G12 8LT, UK.
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12
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Cooper JM, Newby DA, Whyte IM, Carter G, Jones AL, Isbister GK. Serotonin toxicity from antidepressant overdose and its association with the T102C polymorphism of the 5-HT2A receptor. Pharmacogenomics J 2014; 14:390-4. [PMID: 24394202 DOI: 10.1038/tpj.2013.47] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/31/2013] [Accepted: 11/12/2013] [Indexed: 11/10/2022]
Abstract
Serotonin toxicity results from serotonin excess in the central nervous system from serotonergic drugs. Previous studies suggest an association between T102C polymorphism of the serotonin 2A (5-hydroxytryptamine 2A) receptor gene and serotonergic adverse effects with serotonergic drugs. We aimed to determine whether there is an association between the T102C polymorphism and serotonin toxicity in patients taking serotonergic drug overdoses. Ninety-five patients presenting with serotonergic drug overdoses were examined for serotonin toxicity and had blood collected for DNA analysis. A diagnosis of serotonin toxicity was made in 14 patients (15%) based on the Hunter Serotonin Toxicology Criteria. Four of the 14 patients (29%) with serotonin toxicity had the C/C genotype compared with 20/81 (25%) without serotonin toxicity. There were no differences in age or sex, but the median defined daily dose taken by patients with serotonin toxicity was 27 (14-84) compared with 18 (2-136) in patients without serotonin toxicity (P=0.06). There was no association between serotonin toxicity and the T102C polymorphism in patients taking a serotonergic drug overdose.
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Affiliation(s)
- J M Cooper
- 1] Discipline of Clinical Pharmacology, University of Newcastle, Waratah, NSW, Australia [2] Discipline of Pharmacy and Experimental Pharmacology, University of Newcastle, Newcastle, NSW, Australia
| | - D A Newby
- Discipline of Clinical Pharmacology, University of Newcastle, Waratah, NSW, Australia
| | - I M Whyte
- 1] Discipline of Clinical Pharmacology, University of Newcastle, Waratah, NSW, Australia [2] Department of Clinical Toxicology and Pharmacology, Calvary Mater Newcastle, Waratah, NSW, Australia
| | - G Carter
- Department of Liaison Psychiatry, Calvary Mater Newcastle, Waratah, NSW, Australia
| | - A L Jones
- Graduate School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - G K Isbister
- 1] Discipline of Clinical Pharmacology, University of Newcastle, Waratah, NSW, Australia [2] Department of Clinical Toxicology and Pharmacology, Calvary Mater Newcastle, Waratah, NSW, Australia
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13
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Anand S, Nylk J, Neale SL, Dodds C, Grant S, Ismail MH, Reboud J, Cooper JM, McGloin D. Aerosol droplet optical trap loading using surface acoustic wave nebulization. Opt Express 2013; 21:30148-30155. [PMID: 24514593 DOI: 10.1364/oe.21.030148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate the use of surface acoustic wave nebulization (SAWN) to load optical traps. We show that the droplets sizes produced can be tuned by altering the RF frequency applied to the devices, which leads to more control over the sizes of trapped particles. Typically the size distribution of the liquid aerosols delivered using SAWN is smaller than via a standard commercial nebulization device. The ability to trap a range of liquids or small solid particles, not readily accessible using other ultrasonic devices, is also demonstrated both in optical tweezers and dual beam fiber traps.
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14
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Alvarez-Erviti L, Seow Y, Schapira AHV, Rodriguez-Oroz MC, Obeso JA, Cooper JM. Influence of microRNA deregulation on chaperone-mediated autophagy and α-synuclein pathology in Parkinson's disease. Cell Death Dis 2013; 4:e545. [PMID: 23492776 PMCID: PMC3615743 DOI: 10.1038/cddis.2013.73] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 01/17/2013] [Accepted: 01/31/2013] [Indexed: 02/07/2023]
Abstract
The presence of α-synuclein aggregates in the characteristic Lewy body pathology seen in idiopathic Parkinson's disease (PD), together with α-synuclein gene mutations in familial PD, places α-synuclein at the center of PD pathogenesis. Decreased levels of the chaperone-mediated autophagy (CMA) proteins LAMP-2A and hsc70 in PD brain samples suggests compromised α-synuclein degradation by CMA may underpin the Lewy body pathology. Decreased CMA protein levels were not secondary to the various pathological changes associated with PD, including mitochondrial respiratory chain dysfunction, increased oxidative stress and proteasomal inhibition. However, decreased hsc70 and LAMP-2A protein levels in PD brains were associated with decreases in their respective mRNA levels. MicroRNA (miRNA) deregulation has been reported in PD brains and we have identified eight miRNAs predicted to regulate LAMP-2A or hsc70 expression that were reported to be increased in PD. Using a luciferase reporter assay in SH-SY5Y cells, four and three of these miRNAs significantly decreased luciferase activity expressed upstream of the lamp-2a and hsc70 3'UTR sequences respectively. We confirmed that transfection of these miRNAs also decreased endogenous LAMP-2A and hsc70 protein levels respectively and resulted in significant α-synuclein accumulation. The analysis of PD brains confirmed that six and two of these miRNAs were significantly increased in substantia nigra compacta and amygdala respectively. These data support the hypothesis that decreased CMA caused by miRNA-induced downregulation of CMA proteins plays an important role in the α-synuclein pathology associated with PD, and opens up a new avenue to investigate PD pathogenesis.
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Affiliation(s)
- L Alvarez-Erviti
- Department of Clinical Neuroscience, Institute of Neurology, University College London, London, UK
| | - Y Seow
- Molecular Engineering Laboratory, Science and Engineering Institutes, A*STAR, Singapore, Singapore
| | - A HV Schapira
- Department of Clinical Neuroscience, Institute of Neurology, University College London, London, UK
| | - M C Rodriguez-Oroz
- Department of Neurology, Clinica Universidad de Navarra and Medical School, Neuroscience Area, CIMA, University of Navarra, Pamplona, Spain
| | - J A Obeso
- Department of Neurology, Clinica Universidad de Navarra and Medical School, Neuroscience Area, CIMA, University of Navarra, Pamplona, Spain
| | - J M Cooper
- Department of Clinical Neuroscience, Institute of Neurology, University College London, London, UK
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15
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Abstract
Consumer understanding of nutrition and health claims is a key aspect of current regulations in the European Union (EU). In view of this, qualitative and quantitative research techniques were used to investigate consumer awareness and understanding of product claims in the UK, focusing particularly on nutrition claims relating to sugars. Both research methods identified a good awareness of product claims. No added sugars claims were generally preferred to reduced sugars claims, and there was a general assumption that sweeteners and other ingredients would be added in place of sugars. However, there was little awareness of the level of sugar reduction and the associated calorie reduction in products when reduced sugars claims were made on pack. In focus groups, participants felt deceived if sugar reduction claims were being made without a significant reduction in calories. This was reinforced in the quantitative research which showed that respondents expected a similar and meaningful level of calorie reduction to the level of sugar reduction. The research also identified consumer confusion around the calorie content of different nutrients, including over-estimation of the calorie content of sugars. This is crucial to consumers' expectations as they clearly link sugar to calories and therefore expect a reduction in sugar content to deliver a reduction in calorie content.
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16
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Abstract
PURPOSE To examine the important role that primary care nurse practitioners (NPs) have in providing long-term surveillance and health maintenance for breast, prostate, and colorectal cancer survivors throughout the continuum of cancer care. DATA SOURCES MEDLINE, CINAHL, MD-Consult, and Cochrane's databases were utilized with the inclusion of primary research and critical research reviews from January 1995 through March 2008. Select organizational websites were also cited. CONCLUSIONS Cancer patients experience changes in the focus of their care when management shifts from the treatment of cancer to management of treatment side effects and outcomes, to survivorship care, and to secondary cancer treatment. NPs have a strong impact on cancer survivorship care by serving in various roles and settings throughout the cancer trajectory to improve patient outcomes. IMPLICATIONS FOR PRACTICE Cancer survivorship care expands beyond specialty settings, into primary care. NPs have a key role in ensuring continuity of care for patients with cancer. Models of care that promote continuity and high quality of care for patients with cancer include the shared-care and nurse-managed health center models. The formal collaborative plan of care is essential in long-term cancer survivorship care.
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Affiliation(s)
- Joanna M Cooper
- Geisinger Pulmonology, 132 Abigail Lane, Port Matilda, PA 16865, USA.
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17
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Chau KY, Cooper JM, Schapira AHV. Rasagiline protects against alpha-synuclein induced sensitivity to oxidative stress in dopaminergic cells. Neurochem Int 2010; 57:525-9. [PMID: 20624440 PMCID: PMC3769805 DOI: 10.1016/j.neuint.2010.06.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 06/24/2010] [Accepted: 06/25/2010] [Indexed: 12/21/2022]
Abstract
Rasagiline is a propargylamine and irreversible monoamine oxidase (MAO) B inhibitor used for the treatment of Parkinson's disease (PD). It has demonstrated neuroprotective properties in laboratory studies. Current concepts of PD aetiopathogenesis include the role of alpha-synuclein, protein aggregation, free radical metabolism and mitochondrial dysfunction in contributing to cell death. We have used a combination of alpha-synuclein and free radical mediated toxicity in a dopaminergic cell line to provide a model of nigral toxicity in order to investigate the potential molecular mechanisms that mediate rasagiline protection. We demonstrate that rasagiline protects against cell death induced by the combination of free radicals generated by paraquat and either wild-type or A53T mutant alpha-synuclein over-expression. This protection was associated with a reduction in caspase 3 activation, a reduction in superoxide generation and a trend to ameliorate the fall in mitochondrial membrane potential. Rasagiline induced an increase in cellular glutathione levels. The results support a role for rasagiline in protecting dopaminergic cells against free radical mediated damage and apoptosis in the presence of alpha-synuclein over-expression. The data are of relevance to the interpretation of the potential mechanisms of action of rasagiline in explaining the results of disease modification trials in PD.
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Affiliation(s)
- K Y Chau
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, United Kingdom
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18
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Elfström D, Guilhabert B, McKendry J, Poland S, Gong Z, Massoubre D, Richardson E, Rae BR, Valentine G, Blanco-Gomez G, Gu E, Cooper JM, Henderson RK, Dawson MD. Mask-less ultraviolet photolithography based on CMOS-driven micro-pixel light emitting diodes. Opt Express 2009; 17:23522-23529. [PMID: 20052059 DOI: 10.1364/oe.17.023522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report on an approach to ultraviolet (UV) photolithography and direct writing where both the exposure pattern and dose are determined by a complementary metal oxide semiconductor (CMOS) controlled micro-pixellated light emitting diode array. The 370 nm UV light from a demonstrator 8 x 8 gallium nitride micro-pixel LED is projected onto photoresist covered substrates using two back-to-back microscope objectives, allowing controlled demagnification. In the present setup, the system is capable of delivering up to 8.8 W/cm2 per imaged pixel in circular spots of diameter approximately 8 microm. We show example structures written in positive as well as in negative photoresist.
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Affiliation(s)
- D Elfström
- Institute of Photonics, University of Strathclyde, Glasgow G4 0NW, UK
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19
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Bruen PD, Ivanoiu A, Cooper JM, McGeown WJ, Shanks MF, Venneri A. Personal memories and the brain: a voxel based correlation of episodic and semantic autobiographical memory retrieval. Neuroimage 2009. [DOI: 10.1016/s1053-8119(09)70484-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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20
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Leach J, Mushfique H, Keen S, Di Leonardo R, Ruocco G, Cooper JM, Padgett MJ. Comparison of Faxén's correction for a microsphere translating or rotating near a surface. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:026301. [PMID: 19391834 DOI: 10.1103/physreve.79.026301] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Indexed: 05/05/2023]
Abstract
Boundary walls in microfluidic devices have a strong influence on the fluid flow and drag forces on moving objects. The Stokes drag force acting on a sphere translating in the fluid is increased by the presence of a neighboring wall by a factor given by Faxén's correction. A similar increase in the rotational drag is expected when spinning close to a wall. We use optical tweezers to confirm the translational drag correction and report the hitherto unmeasured rotational equivalent. We find that the corrections for the rotational motion is only required for particle-wall separations an order of magnitude shorter than that for the translational cases. These results are particularly significant in the use of optical tweezers for measuring viscosity on a picolitre scale.
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Affiliation(s)
- J Leach
- Department of Physics and Astronomy, University of Glasgow, Glasgow, Scotland.
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21
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Sedgwick H, Caron F, Monaghan PB, Kolch W, Cooper JM. Lab-on-a-chip technologies for proteomic analysis from isolated cells. J R Soc Interface 2008; 5 Suppl 2:S123-30. [PMID: 18534931 PMCID: PMC2706034 DOI: 10.1098/rsif.2008.0169.focus] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [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: 04/29/2008] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 01/21/2023] Open
Abstract
Lab-on-a-chip systems offer a versatile environment in which low numbers of cells and molecules can be manipulated, captured, detected and analysed. We describe here a microfluidic device that allows the isolation, electroporation and lysis of single cells. A431 human epithelial carcinoma cells, expressing a green fluorescent protein-labelled actin, were trapped by dielectrophoresis within an integrated lab-on-a-chip device containing saw-tooth microelectrodes. Using these same trapping electrodes, on-chip electroporation was performed, resulting in cell lysis. Protein release was monitored by confocal fluorescence microscopy.
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Affiliation(s)
- H Sedgwick
- Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8QQ, UK.
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22
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Inya-Agha O, Klauke N, Davies T, Smith G, Cooper JM. Spectroscopic Probing of Dynamic Changes during Stimulation and Cell Remodeling in the Single Cardiac Myocyte. Anal Chem 2007; 79:4581-7. [PMID: 17511420 DOI: 10.1021/ac0622476] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Optical microscopy, involving both fluorescence imaging and confocal Raman microspectroscopy, was used to visualize single, isolated, electrically active heart muscle cells. For example, short-term, dynamic changes in Raman bands during the contraction cycle, as well as persistent band changes during structural remodeling (microscopic rearrangements of cellular structures) in culture over longer periods of time, were obtained from the cellular content (sarcoplasm) of the heart cells. The results of the short-term studies, collected during electrical stimulation, showed dynamic changes in the Raman amide I band intensity, which occurred in phase with changes in cell length during cardiomyocyte contraction. The longer term studies of quiescent cardiomyocytes in culture over 3 days revealed a progressive and sustained increase in the intensity of the amide I band. Over the same period of culture, a decrease in the number of t-tubules (invaginations of the cell membrane, sarcolemma, which ensure the spreading of the action potential into the bulk of the sarcoplasm) was observed using confocal z-sections of the fluorescently labeled sarcolemma. The ability to measure both short-term dynamic changes associated with stimulated contraction and longer term persistent remodeling in the structure of intracellular macromolecules is valuable for assessing the physiological state of the cell, in real time.
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Affiliation(s)
- O Inya-Agha
- Department of Electronics, University of Glasgow, Glasgow G12 8LT, Scotland
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23
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Cooper JM, Schapira AHV. Friedreich's ataxia: coenzyme Q10 and vitamin E therapy. Mitochondrion 2007; 7 Suppl:S127-35. [PMID: 17485244 DOI: 10.1016/j.mito.2007.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 03/30/2007] [Accepted: 04/01/2007] [Indexed: 11/29/2022]
Abstract
Since the identification of the genetic mutation causing Friedreich's ataxia (FRDA) our understanding of the mechanisms underlying disease pathogenesis have improved markedly. The genetic abnormality results in the deficiency of frataxin, a protein targeted to the mitochondrion. There is extensive evidence that mitochondrial respiratory chain dysfunction, oxidative damage and iron accumulation play significant roles in the disease mechanism. There remains considerable debate as to the normal function of frataxin, but it is likely to be involved in mitochondrial iron handling, antioxidant regulation, and/or iron sulphur centre regulation. Therapeutic avenues for patients with FRDA are beginning to be explored in particular targeting antioxidant protection, enhancement of mitochondrial oxidative phosphorylation, iron chelation and more recently increasing FRDA transcription. The use of quinone therapy has been the most extensively studied to date with clear benefits demonstrated using evaluations of both disease biomarkers and clinical symptoms, and this is the topic that will be covered in this review.
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Affiliation(s)
- J M Cooper
- University Department of Clinical Neurosciences, Royal Free and University College Medical School, University College London, Rowland Hill Street, London NW3 2PF, UK.
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24
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Al-Tamimi MAHM, Palframan RJ, Cooper JM, Gibson GR, Rastall RA. In vitro fermentation of sugar beet arabinan and arabino-oligosaccharides by the human gut microflora. J Appl Microbiol 2006; 100:407-14. [PMID: 16430518 DOI: 10.1111/j.1365-2672.2005.02780.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS To determine the fermentation profiles by human gut bacteria of arabino-oligosaccharides of varying degree of polymerization. MATERIALS AND METHODS Sugar beet arabinan was hydrolyzed with a commercial pectinase and eight fractions, of varying molecular weight, were isolated by gel-filtration chromatography. Hydrolysis fractions, arabinose, arabinan and fructo-oligosaccharides were fermented anaerobically by gut bacteria. Total bacteria, bifidobacteria, bacteroides, lactobacilli and the Clostridium perfringens/histolyticum sub. grp. were enumerated using fluorescent in situ hybridization. RESULTS Bifidobacteria were stimulated to different extents depending on molecular weight, i.e. maximum increase in bifidobacteria after 48 h was seen on the lower molecular weight fractions. Lactobacilli fluctuated depending on the initial inoculum levels. Bacteroides numbers varied according to fraction; arabinan, arabinose and higher oligosaccharides (degree of polymerization, dp > 8) resulted in significant increases at 24 h. Only carbohydrate mixtures with dp of 1-2 resulted in significant increases at 48 h (log 8.77 +/- 0.23). Clostridia decreased on all substrates. CONCLUSIONS Arabino-oligosaccharides can be considered as potential prebiotics. SIGNIFICANCE AND IMPACT OF THE STUDY Arabinan is widely available as it is a component of sugar beet pulp, a co-product from the sugar beet industry. Generation of prebiotic functionality from arabinan would represent significant added value to a renewable resource.
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Affiliation(s)
- M A H M Al-Tamimi
- School of Food Biosciences, The University of Reading, Whiteknights, Reading, UK
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25
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Bowden SA, Monaghan PB, Wilson R, Parnell J, Cooper JM. The liquid-liquid diffusive extraction of hydrocarbons from a North Sea oil using a microfluidic format. Lab Chip 2006; 6:740-3. [PMID: 16738724 DOI: 10.1039/b518162c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Extraction of a GC-amenable hydrocarbon fraction from oil by liquid-liquid diffusion across a laminar interface can be performed in a microfluidic format. Analysis of figures of merit, determined using standard analytical techniques, show this method to be an effective new tool for rapidly processing small quantities of oil and petroleum for GC analysis. Methods based upon similar microsystems devices could find widespread use in a variety of fields, including those associated with organic geochemistry and oil exploration and production, where the manipulation of petroleum constituents (greater than C14) is necessary for analytical purposes.
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Affiliation(s)
- S A Bowden
- Department of Geology & Petroleum Geology, University of Aberdeen, Aberdeen AB24 3UE, UK.
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26
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Di Leonardo R, Leach J, Mushfique H, Cooper JM, Ruocco G, Padgett MJ. Multipoint holographic optical velocimetry in microfluidic systems. Phys Rev Lett 2006; 96:134502. [PMID: 16711992 DOI: 10.1103/physrevlett.96.134502] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Indexed: 05/09/2023]
Abstract
We show how holographic optical trapping can be used for the multipoint measurement of fluid flow in microscopic geometries. An array of microprobes can be simultaneously trapped and used to map out the fluid flow in a microfluidic device. The optical traps are alternately turned on and off such that the probe particles are displaced by the flow of the surrounding fluid and then retrapped. The particles' displacements are monitored by digital video microscopy and directly converted into velocity field values. This technique enables the measurement of a two-dimensional flow field at points arbitrarily distributed in a three-dimensional volume. The validity of the technique is demonstrated for the case of the flow around a spinning sphere and the flow at the outlet of a microchannel.
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Affiliation(s)
- R Di Leonardo
- INFM-CRS SOFT c/o Universitá di Roma La Sapienza, I-00185, Roma, Italy.
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27
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Chalmers AF, Kirton R, Wyse CA, Dickie A, Cumming D, Cooper JM, Preston T, Yam PS. Ultrasonographic assessment of the rate of solid-phase gastric emptying in dogs. Vet Rec 2005; 157:649-52. [PMID: 16299365 DOI: 10.1136/vr.157.21.649] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Twelve healthy dogs were used in an ultrasonographic assessment of the effect of the composition of a solid meal on the rate of gastric emptying. The dogs were fasted for nine hours before they were fed either a standard or a high energy density test meal, in a cross-over study design. The gastric antrum was visualised with a 6.5 MHz microconvex transducer, and the area inside the elliptical shape defined by the craniocaudal and ventrodorsal diameters of the stomach was measured. Antral images were acquired at regular intervals for six hours after the ingestion of the test meal. Three indices to describe the rate of gastric emptying were computed: the gastric half-emptying time (t1/2), the time to 50 per cent maximal antral area (t50%), and the time of maximal antral area (tmax). The values of t50% and t1/2 calculated for the high energy density meals were significantly longer than for the standard meals, but there was no significant difference between the tmax values.
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Affiliation(s)
- A F Chalmers
- Department of Companion Animal Studies, Institute of Comparative Medicine, University of Glasgow Veterinary School, Bearsden, Glasgow
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28
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Wyse CA, Hammond J, Arteaga A, Cumming D, Cooper JM, McEwan JD, Yam PS. Collection and analysis of exhaled breath condensate hydrogen peroxide in conscious healthy dogs. Vet Rec 2004; 155:744-6. [PMID: 15623088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- C A Wyse
- Institute of Comparative Medicine, Department of Veterinary Clinical Studies, University of Glasgow Veterinary School, Bearsden, Glasgow G61 IQH
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29
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Orth M, Tabrizi SJ, Tomlinson C, Messmer K, Korlipara LVP, Schapira AHV, Cooper JM. G209A mutant alpha synuclein expression specifically enhances dopamine induced oxidative damage. Neurochem Int 2004; 45:669-76. [PMID: 15234109 DOI: 10.1016/j.neuint.2004.03.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 03/17/2004] [Indexed: 11/25/2022]
Abstract
Alpha synuclein protein may play an important role in familial and sporadic Parkinson's disease pathology. We have induced G209A mutant or wild-type alpha-synuclein expression in stable HEK293 cell models to determine if this influences markers of oxidative stress and damage under normal conditions or in the presence of dopamine or paraquat. Induced wild-type or mutant alpha-synuclein expression alone had no effect upon levels of oxidative stress or damage, as measured by glutathione levels or aconitase activity. Both wild-type and mutant alpha-synuclein expression decreased the oxidative damage induced by paraquat, although the protection was less marked with mutant alpha-synuclein expression. This suggests that alpha-synuclein expression may either have anti-oxidant properties or may upregulate cellular antioxidant levels, a function that was diminished by the G209A mutation. However, mutant but not wild-type alpha-synuclein expression specifically enhanced dopamine associated oxidative damage. Non-expressing cells treated with reserpine to inhibit the vesicular monoamine compartmentalisation produced similar results. However, consistent with the hypothesis that mutant alpha-synuclein disrupts vesicular dopamine compartmentalization, this effect was diminished in cells expressing mutant alpha-synuclein. This may result in increased dopamine metabolism and cause selective oxidative damage to dopaminergic cells.
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Affiliation(s)
- M Orth
- University Department of Clinical Neurosciences, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK
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30
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Wyse CA, Love S, Christley RM, Yam PS, Cooper JM, Cumming DRS, Preston T. Validation of a method for collection and assay of pentane in the exhaled breath of the horse. Res Vet Sci 2004; 76:109-12. [PMID: 14672852 DOI: 10.1016/j.rvsc.2003.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Oxidative stress refers to an imbalance between the production of oxidising free radicals and the antioxidant defenses of the cell, and is associated with many pathogenic processes. Oxidative damage to cellular lipids results in the evolution of pentane and ethane gas, and detection of these hydrocarbons in the exhaled breath can be used to monitor in vivo oxidative stress. The aim of this study was to validate a gas chromatography (GC) method for measurement of breath pentane in the horse. The GC-system developed showed good specificity for discrimination of pentane from other breath hydrocarbons, and was sensitive to 0.5 ppb pentane. Pentane was detected in the exhaled breath of five horses investigated on two occasions. The results of this preliminary study demonstrate that breath pentane can be measured in the horse, and further work is now justified to investigate the feasibility of applying this method for monitoring in vivo oxidative stress in the horse.
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Affiliation(s)
- C A Wyse
- Department of Veterinary Clinical Studies, Institute of Comparative Medicine, University of Glasgow Veterinary School, Bearsden Road, Bearsden, G61 1QH, Glasgow, UK.
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31
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Wyse CA, Preston T, Yam PS, Sutton DGM, Christley RM, Hotchkiss JW, Mills CA, Glidle A, Cumming DRS, Cooper JM, Love S. Current and future uses of breath analysis as a diagnostic tool. Vet Rec 2004; 154:353-60. [PMID: 15074325 DOI: 10.1136/vr.154.12.353] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The analysis of exhaled breath is a potentially useful method for application in veterinary diagnostics. Breath samples can be easily collected from animals by means of a face mask or collection chamber with minimal disturbance to the animal. After the administration of a 13C-labelled compound the recovery of 13C in breath can be used to investigate gastrointestinal and digestive functions. Exhaled hydrogen can be used to assess orocaecal transit time and malabsorption, and exhaled nitric oxide, carbon monoxide and pentane can be used to assess oxidative stress and inflammation. The analysis of compounds dissolved in the aqueous phase of breath (the exhaled breath condensate) can be used to assess airway inflammation. This review summarises the current status of breath analysis in veterinary medicine, and analyses its potential for assessing animal health and disease.
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Affiliation(s)
- C A Wyse
- Institute of Comparative Medicine, University of Glasgow Veterinary School, Bearsden, Glasgow G61 1QH
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Abstract
Plasma malondialdehyde (MDA) levels were raised in Friedreich's ataxia (FRDA) patients. These levels correlated with increasing age and disease duration, suggesting lipid peroxidation increased with disease progression. Using fibroblasts from FRDA patients we observed that GSH levels and aconitase activities were normal, suggesting their antioxidant status was unchanged. When exposed to various agents to increase free radical generation we observed that intracellular superoxide generation induced by paraquat caused enhanced oxidative damage. This correlated with the size of the GAA1 expansion, suggesting decreased frataxin levels may render the cells more vulnerable to mild oxidative stress. More severe oxidative stress induced by hydrogen peroxide caused increased cell death in FRDA fibroblasts but was not significantly different from control cells. We propose that abnormal respiratory chain function and iron accumulation may lead to a progressive increase in oxidative damage, but increased sensitivity to free radicals may not require detectable respiratory chain dysfunction.
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Affiliation(s)
- J L Bradley
- Department of Clinical Neuroscience, Royal Free and University College Medical School, University College London, Rowland Hill Street, London NW3 2PF, United Kingdom
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Docherty FT, Monaghan PB, Keir R, Graham D, Smith WE, Cooper JM. The first SERRS multiplexing from labelled oligonucleotides in a microfluidics lab-on-a-chip. Chem Commun (Camb) 2003:118-9. [PMID: 14737360 DOI: 10.1039/b311589e] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first simultaneous detection of three dye-labelled oligonucleotides in a microfluidics chip by SERRS is reported.
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Affiliation(s)
- Frances T Docherty
- Department of Pure and Applied Chemistry, University of Strathclyde, Cathedral Street, Glasgow, UKG1 1XL
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Abstract
Mitochondrial dysfunction has been implicated in the aetiology of sporadic Parkinson's disease but its role in the disease mechanism is not clear. We have investigated the short term effect of G209A mutant or wild-type alpha-synuclein expression upon mitochondrial function using stable inducible cell models. Mitochondrial respiratory chain activities and membrane potential were normal suggesting that increased wild-type or mutant alpha-synuclein expression did not directly affect these parameters. However, both wild-type and mutant G209A alpha-synuclein expression enhanced the fall in mitochondrial membrane potential induced by the complex I inhibitor rotenone. This suggests an indirect interaction between alpha-synuclein expression and mitochondrial function which could render the mitochondria more vulnerable to inhibition by potential endogenous or exogenous factors found in dopaminergic neurones.
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Affiliation(s)
- M Orth
- University Department of Clinical Neuroscience, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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Abstract
Huntington's disease (HD) is an autosomal dominant disorder caused by an expansion in the number of glutamine repeats in the N-terminal region of the huntingtin protein. Nuclear and cytoplasmic aggregates of the N-terminal portion of huntingtin have been found in the brains of HD patients and the brains and non-neuronal tissues of the R6/2 HD transgenic mouse. We have cultured myoblasts and myotubes from transgenic R6/2 mice and littermate controls to investigate the formation of these inclusions in post mitotic cells. Huntingtin immunoreactivity was intense in differentiating, desmin positive myoblasts and myotubes from both control and R6/2 mice suggesting that it may play a role in myotube differentiation. Following differentiation huntingtin and ubiquitin positive aggregates were observed in R6/2 but not control cultures. After 3 weeks in differentiation medium cytoplasmic huntingtin and ubiquitin immunoreactive aggregates were observed in non-myotube cells, while nuclear huntingtin aggregates were seen in a proportion of myotubes after 6 weeks. Growth in the absence of serum resulted in a marked increase in the number of R6/2 myotubes containing nuclear inclusions after 6 weeks demonstrating that environmental factors influenced huntingtin aggregate formation in these cells. Consequently, cultured myotubes from R6/2 mice may be a useful post mitotic cell culture model to study both the biochemical consequences of huntingtin aggregates and the factors that may influence aggregate formation.
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Affiliation(s)
- M Orth
- University Department of Clinical Neurosciences, Royal Free and University College Medical College, University College London, UK
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Wyse CA, Yam PS, Slater C, Cooper JM, Preston T. A comparison of the rate of recovery of 13CO2 in exhaled breath with 2H in body water following ingestion of [2H/13C]octanoic acid in a dog. Res Vet Sci 2003; 74:123-7. [PMID: 12589736 DOI: 10.1016/s0034-5288(02)00178-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The objective of this study was to assess post-gastric processing of octanoic acid (OA) by comparing the rate of recovery of 13C in breath with the rate of recovery of 2H in saliva following ingestion of [2H/13C]OA. A test meal with 100mg [13C]OA and 750 mg [2H]OA was ingested on two separate occasions by one dog. Exhaled breath and saliva samples were collected at set time points for 6h following ingestion of the test meal. Two indices were computed, half recovery time (t(1/2)) and the time of peak excretion (t(max)). Recovery of 2H in saliva was quicker than recovery of 13C in breath as determined by the difference in the indices for each isotope; 1.33 and 1.59 h for t(1/2) and t(max), respectively. These findings suggest that the post-gastric processing of OA imposes a delay on the recovery of 13C in breath in the dog, as occurs in man and in the horse.
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Affiliation(s)
- C A Wyse
- Department of Veterinary Clinical Studies, University of Glasgow Veterinary School, Bearsden, UK.
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Affiliation(s)
- J M Cooper
- Department of Clinical Neuroscience, Royal Free & University College Medical School, London, NW3 2PF, United Kingdom
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Abstract
Mitochondria clearly play a central role in the pathogenesis of Friedreich's Ataxia. The most common genetic abnormality results in the deficiency of the protein frataxin, which is targeted to the mitochondrion. Research since this discovery has indicated that mitochondrial respiratory chain dysfunction, mitochondrial iron accumulation and oxidative damage are important components of the disease mechanism. While the role of frataxin is not known, evidence is currently pointing to a role in either mitochondrial iron handling or iron sulphur centre synthesis. These advances in our understanding of the disease mechanisms are enabling therapeutic avenues to be explored, in particular the use of established drugs such as antioxidants and enhancers of respiratory chain function. Vitamin E therapy has been shown to be beneficial in patients with ataxia with vitamin E deficiency, and CoQ10 therapy was effective in some patients with ataxia associated with CoQ10 deficiency. A combined therapy involving long term treatment with high doses of vitamin E and coenzyme Q10 has jointly targeted two of the major features of Friedreich's Ataxia; decreased mitochondrial respiratory chain function and increased oxidative stress. This therapy clearly showed a rapid and sustained increase in the energy generated by the FRDA heart muscle, nearly returning to normal levels. The improvements in skeletal muscle energy generation parallel those of the heart but to a lower level. While this therapy appeared to slow the predicted progression of some clinical symptoms a larger placebo controlled study is required to confirm these observations. Other antioxidant strategies have involved the use of Idebenone, selenium and N acetyl cysteine but only the use of Idebenone has involved structured trials with relatively large patient numbers. Idebenone clearly had an impact upon the cardiac hypertrophy in the majority of patients, although there have not been any other significant benefits reported to date.
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Affiliation(s)
- J M Cooper
- University Department of Clinical Neurosciences, Royal Free & University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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Abstract
Adaptive Profiling (APL) and other biochip companies aim to harness the power of microsystems technology together with advances in chemistry and molecular biology, to become service and technology providers to organizations involved in pharmaceutical research and development. By supplying a unique range of decision-making tools that aid an earlier identification of qualified drug candidates for clinical development, the company should gain a significant share of the 10 billion US dollar biological screening, bioavailability and toxicity assessment market.
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Affiliation(s)
- J M Cooper
- Department of Electronics, University of Glasgow, Glasgow G12 8LT, Scotland, UK.
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Juárez-Martínez G, Steinmann P, Roszak AW, Isaacs NW, Cooper JM. High-throughput screens for postgenomics: studies of protein crystallization using microsystems technology. Anal Chem 2002; 74:3505-10. [PMID: 12139061 DOI: 10.1021/ac0112519] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes the fabrication of a micromachined miniaturized array of chambers in a 2-mm-thick single crystal (100) silicon substrate for the combinatorial screening of the conditions required for protein crystallization screening (including both temperature and the concentration of crystallization agent). The device was fabricated using standard photolithography techniques, reactive ion etching (RIE) and anisotropic silicon wet etching to produce an array of 10 x 10 microchambers, with each element having a volume of 5 microL. A custom-built temperature controller was used to drive two peltier elements in order to maintain a temperature gradient (between 12 and 40 degrees C) across the device. The performance of the microsystem was illustrated by studying the crystallization of a model protein, hen egg white lysozyme. The crystals obtained were studied using X-ray diffraction at room temperature and exhibited 1.78 A resolution. The problems of delivering a robust crystallization protocol, including issues of device fabrication, delivery of a reproducible temperature gradient, and overcoming evaporation are described.
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Abstract
Interconnected lab-on-a-chip modules with minimal dead volume have been developed resulting in the 'plug and play' concept based upon a reversible bonding process. This paper describes the detail of a chip to chip interconnection method, where devices have been aligned and bonded within 15 min and rapidly disassembled in under 5 min. The transport of fluorescein between the chip modules was used as a model microfluidic system and analysed in order to demonstrate the electrophoretic performance of the device and the interconnected junction. Using this technology, in the future different modules for various applications can be developed and interconnected, depending on the required applications. In addition, this simple but rapid method of chip to chip connection overcomes potential problems associated with integrating incompatible materials on one device.
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Affiliation(s)
- E Igata
- Department of Electronics and Electrical Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, UKG12 8LT
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Lodi R, Rajagopalan B, Bradley JL, Taylor DJ, Crilley JG, Hart PE, Blamire AM, Manners D, Styles P, Schapira AHV, Cooper JM. Mitochondrial dysfunction in Friedreich's ataxia: from pathogenesis to treatment perspectives. Free Radic Res 2002; 36:461-6. [PMID: 12069111 DOI: 10.1080/10715760290021324] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Friedreich's ataxia (FRDA), the most common inherited ataxia, is an autosomal recessive degenerative disorder caused by a GAA triplet expansion or point mutations in the FRDA gene on chromosome 9q13. The FRDA gene product, frataxin, is a widely expressed mitochondrial protein, which is severely reduced in FRDA patients. The demonstration that deficit of frataxin in FRDA is associated with mitochondrial iron accumulation, increased sensitivity to oxidative stress, deficit of respiratory chain complex activities and in vivo impairment of cardiac and skeletal muscle tissue energy metabolism, has established FRDA as a "new" nuclear encoded mitochondrial disease. Pilot studies have shown the potential effect of antioxidant therapy based on idebenone or coenzyme Q10 plus Vitamin E administration in this condition and provide a strong rationale for designing larger randomized clinical trials.
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Affiliation(s)
- R Lodi
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Universitá di Bologna, Policlinico S. Orsola, Italy.
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Affiliation(s)
- J M Cooper
- Brigham and Women's Hospital, Boston, Massachusetts, USA
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Wyse CA, Preston T, Love S, Morrison DJ, Cooper JM, Yam PS. Use of the 13C-octanoic acid breath test for assessment of solid-phase gastric emptying in dogs. Am J Vet Res 2001; 62:1939-44. [PMID: 11763185 DOI: 10.2460/ajvr.2001.62.1939] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the 13C-octanoic acid breath test for determining gastric emptying in dogs. ANIMALS 6 healthy adult dogs. PROCEDURE Food was withheld for 12 hours before each test. Expired air was collected 30 minutes and immediately before each test and at frequent intervals thereafter for 6 hours. Concentration of 13CO2 in expired air was determined by use of continuous-flow isotope-ratio mass spectrometry. Basal concentration of 13CO2 was measured in dogs that were not fed a test meal. Effects of the standard unlabeled test meal on basal concentration of 13CO2 were then assessed. The optimum dose of substrate was determined by measuring 13CO2 concentration after ingestion of the standard test meal containing 50 or 100 mg of 13C-octanoic acid, whereas effect of energy density of the test meal on gastric emptying was determined after ingestion of the standard or high-energy labeled test meal. Gastric emptying coefficient (GEC), time to peak 13CO2 concentration (tmax), and half-dose recovery time (t(1/2)) were calculated. RESULTS Basal concentration of 13CO2 in expired air was not significantly affected by ingestion of the unlabeled test meal. However, 13CO2 concentration significantly increased in a dose-dependent manner after ingestion of the labeled meal. Gastric emptying coefficient, and were significantly different between dogs fed the standard and high-energy test meals, indicating that ingestion of a high-energy meal delays gastric emptying. CONCLUSIONS AND CLINICAL RELEVANCE The 13C-octanoic acid breath test may be a useful noninvasive and nonradioactive method for assessment of gastric emptying in dogs.
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Affiliation(s)
- C A Wyse
- Department of Electronics and Electrical Engineering, University of Glasgow, UK
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Glidle A, Bailey L, Hadyoon CS, Hillman AR, Jackson A, Ryder KS, Saville PM, Swann MJ, Webster JR, Wilson RW, Cooper JM. Temporal and spatial profiling of the modification of an electroactive polymeric interface using neutron reflectivity. Anal Chem 2001; 73:5596-606. [PMID: 11816593 DOI: 10.1021/ac0104882] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electropolymerized films of the functionalized pyrrole, pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), were reacted with a solution-phase nucleophile, ferrocene ethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymer membrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reaction profile within the electrodeposited polymer membrane after nucleophilic substitution is presented. This was achieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained from XPS, FT-IR, and electrochemical measurements. The results presented illustrate how, for a partially reacted film resulting from a short reaction time, the extent of reaction with ferrocene ethylamine is not homogeneous throughout the thickness of the film, but occurs predominantly at the polymer/solution interface. We show that the progress of the reaction within the polymer film is limited by the transport of reacting species in the dense regions of the membrane that are furthest from the solution interface. The data do not fit an alternative model in which there is spatially homogeneous progression of the reaction front throughout the bulk of the thin film polymer. Guided by the neutron reflectivity measurements, suitable modifications were made to the electrodeposition method to prepare films whose architecture resulted in faster rates of reaction.
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Affiliation(s)
- A Glidle
- Department of Electronics, Glasgow University, UK
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46
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Lodi R, Rajagopalan B, Blamire AM, Cooper JM, Davies CH, Bradley JL, Styles P, Schapira AH. Cardiac energetics are abnormal in Friedreich ataxia patients in the absence of cardiac dysfunction and hypertrophy: an in vivo 31P magnetic resonance spectroscopy study. Cardiovasc Res 2001; 52:111-9. [PMID: 11557239 DOI: 10.1016/s0008-6363(01)00357-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
OBJECTIVE Friedreich ataxia (FRDA), the commonest form of inherited ataxia, is often associated with cardiac hypertrophy and cardiac dysfunction is the most frequent cause of death. In 97%, FRDA is caused by a homoplasmic GAA triplet expansion in the FRDA gene on chromosome 9q13 that results in deficiency of frataxin, a mitochondrial protein of unknown function. There is evidence that frataxin deficiency leads to a severe defect of mitochondrial respiration associated with abnormal mitochondrial iron accumulation. To determine whether bioenergetics deficit underlies the cardiac involvement in Friedreich ataxia (FRDA) we measured cardiac phosphocreatine to ATP ratio non-invasively in FRDA patients. METHODS AND RESULTS Eighteen FRDA patients and 18 sex- and age-matched controls were studied using phosphorus MR spectroscopy and echocardiography. Left ventricular hypertrophy was present in eight FRDA patients while fractional shortening was normal in all. Cardiac PCr/ATP in FRDA patients as a group was reduced to 60% of the normal mean (P<0.0001). In the sub-group of patients with no cardiac hypertrophy PCr/ATP was also significantly reduced (P<0.0001). CONCLUSION Cardiac bioenergetics, measured in vivo, is abnormal in FRDA patients in the absence of any discernible deterioration in cardiac contractile performance. The altered bioenergetics found in FRDA patients without left ventricle hypertrophy implies that cardiac metabolic dysfunction in FRDA precedes hypertrophy and is likely to play a role in its development.
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Affiliation(s)
- R Lodi
- MRC Biochemical and Clinical Magnetic Resonance Unit, Department of Biochemistry, University of Oxford and Oxford Radcliffe Hospital, Oxford, UK.
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Pook MA, Al-Mahdawi S, Carroll CJ, Cossée M, Puccio H, Lawrence L, Clark P, Lowrie MB, Bradley JL, Cooper JM, Koenig M, Chamberlain S. Rescue of the Friedreich's ataxia knockout mouse by human YAC transgenesis. Neurogenetics 2001; 3:185-93. [PMID: 11714098 DOI: 10.1007/s100480100118] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We have generated and characterised transgenic mice that contain the entire Friedreich's ataxia gene (FRDA) within a human YAC clone of 370 kb. In an effort to overcome the embryonic lethality of homozygous Frda knockout mice and to study the behaviour of human frataxin in a mouse cellular environment, we bred the FRDA YAC transgene onto the null mouse background. Phenotypically normal offspring that express only YAC-derived human frataxin were identified. The human frataxin was expressed in the appropriate tissues at levels comparable to the endogenous mouse frataxin, and it was correctly processed and localised to mitochondria. Biochemical analysis of heart tissue demonstrated preservation of mitochondrial respiratory chain function, together with some increase in citrate synthase and aconitase activities. Thus, we have demonstrated that human frataxin can effectively substitute for endogenous murine frataxin in the null mutant. Our studies are of immediate consequence for the generation of Friedreich's ataxia transgenic mouse models, and further contribute to the accumulating knowledge of human-mouse functional gene replacement systems.
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Affiliation(s)
- M A Pook
- Division of Biomedical Sciences, Imperial College School of Medicine, London, UK.
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Abstract
There is evidence that 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP) toxicity is mediated through both inhibition of mitochondrial complex I and free radical generation. 7-Nitroindazole protects against MPTP toxicity in vitro and in vivo, and this appears to be related to its inhibition of nitric oxide (NO(*-)) synthase. We now show that the NO(*-) generator, glutathione-N-oxide, enhances the inhibitory action of 1-methyl-4-phenylpyridinium (MPP(+)) on complex I activity in brain submitochondrial particles. We propose that the NO(*-)-induced reversible inhibition of complex IV (cytochrome oxidase) potentiates the MPP(+)-induced irreversible free radical-mediated inhibition of complex I. Thus, NO(*-) may 'prime' the respiratory chain to the effects of MPP(+). These data provide evidence for an interaction between NO(*-) and MPP(+) at the level of the respiratory chain.
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Affiliation(s)
- M W Cleeter
- University Department of Clinical Neurosciences, Royal Free and University College Medical School, London, UK
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Abstract
Rats fed a vitamin E-depleted diet for 48 weeks had undetectable levels of vitamin E in the gastrocnemius muscle and liver, leading to elevated malondialdehyde levels in both tissues and an elevated GSH level in muscle. Skeletal-muscle mitochondria showed decreased mitochondrial respiratory chain (MRC) activities, whereas liver MRC activities were increased. Exposure of normal rat liver submitochondrial particles (SMPs) to an in vitro NADPH-dependent lipid peroxidation system resulted in a dose-dependent increase in lipid peroxidation and inhibition of complex I and complex IV activities. Complex I exhibited greater sensitivity to lipid peroxidation than complex IV. At low and high NADPH concentrations, the rate of lipid peroxidation and the level of enzyme inhibition were essentially the same in liver SMPs from both vitamin E-deficient and control rats, suggesting that under these conditions, the loss of vitamin E did not exacerbate the effects of either lipid peroxidation or enzyme inhibition. These results indicate that normal vitamin E levels in liver mitochondria are not required for protection against lipid peroxidation and are consistent with the normal liver mitochondrial function in vitamin E-deficient animals. This suggests other antioxidants, such as ubiquinol and GSH, may be more important in protecting liver mitochondria and MRC from lipid peroxidation.
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Affiliation(s)
- R Rafique
- University Department of Clinical Neuroscience, Royal Free & University College Medical School, Rowland Hill Street, London NW3 2PF, UK
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