Emerging potentials of Fe-based nanomaterials for chiral sensing and imaging

Fe-based nanostructures have possessed promising properties that make it suitable for chiral sensing and imaging applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photostability, tunable fluorescence, and water solubility. This review summarizes the recent research progress in the field of Fe-based nanostructures and places special emphases on their applications in chiral sensing and imaging. The synthetic strategies to prepare the targeted Fe-based structures were also introduced. The chiral sensing and imaging applications of the nanostructures are discussed in details.

Magnetoplasmonic photonic arrays for rapid and selective colorimetric detection of chloride ions in water

The rapid and efficient detection of chloride (Cl-) ions is crucial in a variety of fields, making the development of advanced sensing methods such as colorimetric sensors an imperative advancement in analytical chemistry. Herein, a novel, selective, and straightforward paper-based colorimetric sensing platform has been developed utilizing an amorphous photonic array (APA) of magnetoplasmonic Ag@Fe3O4 nanoparticles (MagPlas NPs) for the detection of Cl- in water. Taking advantage of the highly responsive APA, the key principle of this sensing method is based on the chemical reaction between Ag+ and Cl-, which results in the precipitation of high-refractive index (RI) AgCl. This assay, distinct from typical plasmonic sensors that rely heavily on nanoparticle aggregation/anti-aggregation, is premised on the precipitation reaction of Ag+ and Cl-. In the presence of Cl-, a rapid, distinctive color alteration from royal purple to a dark sky blue is visually observable within a short time of a few minutes, eliminating the necessity for any surface modification procedures. Comprehensive assessments substantiated that these sensors display commendable sensitivity, selectivity, and stability, thereby establishing their effective applicability for Cl- analysis in various technological fields.

Rugged Forest Morphology of Magnetoplasmonic Nanorods that Collect Maximum Light for Photoelectrochemical Water Splitting

A feasible nanoscale framework of heterogeneous plasmonic materials and proper surface engineering can enhance photoelectrochemical (PEC) water-splitting performance owing to increased light absorbance, efficient bulk carrier transport, and interfacial charge transfer. This article introduces a new magnetoplasmonic (MagPlas) Ni-doped Au@Fex Oy nanorods (NRs) based material as a novel photoanode for PEC water-splitting. A two stage procedure produces core-shell Ni/Au@Fex Oy MagPlas NRs. The first-step is a one-pot solvothermal synthesis of Au@Fex Oy . The hollow Fex Oy nanotubes (NTs) are a hybrid of Fe2 O3 and Fe3 O4 , and the second-step is a sequential hydrothermal treatment for Ni doping. Then, a transverse magnetic field-induced assembly is adopted to decorate Ni/Au@Fex Oy on FTO glass to be an artificially roughened morphologic surface called a rugged forest, allowing more light absorption and active electrochemical sites. Then, to characterize its optical and surface properties, COMSOL Multiphysics simulations are carried out. The core-shell Ni/Au@Fex Oy MagPlas NRs increase photoanode interface charge transfer to 2.73 mAcm-2 at 1.23 V RHE. This improvement is made possible by the rugged morphology of the NRs, which provide more active sites and oxygen vacancies as the hole transfer medium. The recent finding may provide light on plasmonic photocatalytic hybrids and surface morphology for effective PEC photoanodes.

Matrix-assisted laser desorption/ionization-Fourier-transform ion cyclotron resonance-mass spectrometry analysis of exosomal lipids from human serum

RATIONALE

Exosomes contain biomarkers such as proteins and lipids that help in understanding normal physiology and diseases. Lipids, in particular, are infrequently studied using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) for biomarker discovery. In this study, MALDI was equipped with a high-resolution MS to investigate exosomal lipids from human serum.

METHODS

Exosomal lipids were profiled using MALDI with Fourier-transform ion cyclotron resonance (FTICR)-MS. Four matrices (i.e., α-cyano-4-hydroxycinnamic acid [CHCA], 2,5-dihydroxybenzoic acid, sinapinic acid, and graphene oxide [GO]) and three sample preparation methods (i.e., dried droplet, thin layer, and two layer) were compared for the number of lipid species detected and the relative abundance of each lipid from human serum and human serum exosomes.

RESULTS

In sum, 172 and 89 lipid species were identified from human serum and human serum exosomes, respectively, using all the methods. The highest number of exosome lipid species, 69, was detected using the CHCA matrix, whereas only 8 exosome lipid species were identified using the GO matrix. Among the identified lipid species, phosphatidylcholine was identified most frequently, probably due to the use of a positive ion mode.

CONCLUSIONS

Exosomes and human serum showed comparable lipid profiles as determined using MALDI-FTICR-MS. These findings provide a new perspective on exosomal lipidomics analysis and may serve as a foundation for future lipidomics-based biomarker research using MALDI-FTICR-MS.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

One-Pot Synthesis of Magnetoplasmonic Au@FexOy Nanowires: Bioinspired Bouligand Chiral Stack

One-dimensional hybrid nanostructures composed of a plasmonic gold nanowire core covered by a shell of magnetic oxide nanoparticles (Au@Fe_xO_y NWs) were synthesized by a one-pot solvothermal synthesis process. The effects of reaction temperature, time, reducing agent, and precursor as well as postsynthesis treatment were optimized to produce highly uniform NWs with a diameter of 226 ± 25 nm and a plasmonic core aspect ratio of 25 to 82. By exploiting the interaction of NWs with an external magnetic field, precise arrangements into highly periodic photonic structures were achieved, which can generate distinctive structural colors that are vividly iridescent and polarization-sensitive. Furthermore, a Bouligand-type chiral nematic film consisting of multistacked unidirectional layers of achiral NWs was fabricated using a modified layer-by-layer deposition method, which displays circular dichroism (CD) and chiral sensing capability. The addition of bovine serum albumin (BSA) as a model protein analyte induced a concentration-dependent wavelength shift of CD peaks. These intriguing properties of magnetoplasmonic anisotropic NWs and their self-assemblies could be consequently valuable for developing nature-inspired structural color imprints as well as solid-state chiral sensing devices.

Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins

Bacillus spores are highly resistant to toxic chemicals and extreme environments. Because some Bacillus species threaten public health, spore inactivation techniques have been intensively investigated. We exposed Bacillus atrophaeus spores to a 266 nm Nd:YVO₄ laser at a laser power of 1 W and various numbers of scans. As a result, the UV laser reduced the viability of Bacillus atrophaeus spores. Although the outer coat of spores remained intact after UV laser irradiation of 720 scans, damage inside the spores was observed. Spore proteins were identified by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry during the course of UV laser irradiation. Photochemical and photothermal processes are believed to be involved in the UV laser sterilization of Bacillus spores. Our findings suggest that a UV laser is capable of sterilizing Bacillus atrophaeus spores.

Label-free quantitative proteomic analysis of serum extracellular vesicles differentiating patients of alcoholic and nonalcoholic fatty liver diseases

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are typically asymptomatic and slow-progressing but potentially fatal diseases that are common causes of liver cirrhosis and related complications. Exosomes are nano-sized extracellular vesicles that have been linked to various intercellular communication processes and can carry biological materials reflecting the state and severity of disease. In this study, shotgun proteomic analysis of the protein expression profiles of extracellular vesicles, including exosomes and microvesicles, enriched from human serum samples of 24 patients diagnosed with various fatty liver diseases was performed using liquid chromatography tandem mass spectrometry (LC-MS/MS) followed by protein identification and label-free quantification using the MaxQuant platform. A total of 329 proteins, including 190 previously reported exosome-specific proteins, were identified from four types of liver disease, where significant differences in protein expression were found in apolipoproteins, immunoglobulins, and other previously reported markers of liver disease. Principal component analysis of 61 proteins identified from MaxQuant analysis of the LC-MS/MS data provided a confident differentiation between ALD and NAFLD. SIGNIFICANCE: The current investigation revealed the difference among various types of liver disease using LC-MS/MS of exosomes enriched from human serum samples of 24 patients where the most significantly up-regulation proteins were alpha-2-macroglobulin for alcoholic hepatitis and apolipoprotein C3 for nonalcoholic fatty liver disease.

Development of a Core Outcome Set for clinical trials aimed at improving antimicrobial stewardship in care homes

Introduction

Diverse outcomes reported in clinical trials to improve antimicrobial stewardship (AMS) in care homes has hindered evidence synthesis [1]. We previously reported that a number of outcomes for care home AMS which may be important to healthcare professionals and relatives of care home residents had not been measured in previous trials [2]. It is essential to generate a set of important outcomes (a core outcome set – COS) for future studies of AMS interventions in care homes.

Aim

To develop a COS for use in clinical trials aimed at improving AMS in care homes.

Methods

A refined inventory of outcomes for AMS interventions in care homes, compiled from a previous study [2], was presented in a three-round international Delphi consensus survey, followed by an online consensus exercise. Stakeholders engaged in AMS in care homes (e.g. healthcare professionals, representatives of care home residents) were invited to participate, having been identified through the research team’s contacts and knowledge of relevant organisations. A 9-point Likert scale was used during the consensus procedures and an outcome was included in the COS if 80% or more of participants scored between 7 and 9, and 15% or less scored between 1 and 3. Less stringent criteria for inclusion were also applied if the final COS comprised fewer than three outcomes. Subsequently, a suitable outcome measurement instrument (OMI) was selected for each outcome in the COS using the following steps: finding existing OMIs in the literature and consulting with experts, assessing the quality of OMIs, and selecting one OMI for each core outcome via a two-round international Delphi consensus exercise. Consent was obtained from all participants taking part in all consensus procedures.

Results

The initial inventory of 14 outcomes was presented to 82 international Delphi panellists from 17 countries in the first round who also suggested three additional outcomes. These 17 outcomes were rated again in two further rounds, with consensus achieved for ten outcomes. A subsequent online consensus exercise with twelve participants from Northern Ireland, including the research team, reached consensus to include five outcomes in the COS (Table 1). Regarding selection of OMIs for the COS, 17 OMIs were identified through literature searches and experts’ suggestions. Based on quality assessment, three OMIs - ‘Number of antimicrobial courses started per 1000 resident-days’, ‘Rate of antimicrobial days of therapy per 1000 resident-days’, and ‘Van Buul algorithms to evaluate appropriateness of initiating or withholding antibiotics’ - were selected for a two-round Delphi exercise with 59 participants from 16 countries. Consensus was reached to select two OMIs for the COS, as presented in Table 1.

Conclusion

This is the first study to develop a COS for use in clinical trials aimed at improving AMS in care homes. Although we recruited few representatives from advocacy groups for older people, care home staff and managers, there was common agreement for inclusion of a number of outcomes. This COS represents the minimum that should be used in research and trialists may consider exploring other outcomes as reported in previous studies.

References

1. Nguyen HQ, Tunney MM, Hughes CM. Interventions to Improve Antimicrobial Stewardship for Older People in Care Homes: A Systematic Review. Drugs and Aging. 2019;36(4):355–69.

2. Nguyen HQ, Bradley DT, Tunney MM, Hughes CM. Antimicrobial Stewardship in Care Homes: Outcomes of Importance to Stakeholders. J Hosp Infect. 2020 Jan 27;104(4):582–91.

Photonic-Plasmonic Nanostructures for Solar Energy Utilization and Emerging Biosensors

Issues related to global energy and environment as well as health crisis are currently some of the greatest challenges faced by humanity, which compel us to develop new pollution-free and sustainable energy sources, as well as next-generation biodiagnostic solutions. Optical functional nanostructures that manipulate and confine light on a nanometer scale have recently emerged as leading candidates for a wide range of applications in solar energy conversion and biosensing. In this review, recent research progress in the development of photonic and plasmonic nanostructures for various applications in solar energy conversion, such as photovoltaics, photothermal conversion, and photocatalysis, is highlighted. Furthermore, the combination of photonic and plasmonic nanostructures for developing high-efficiency solar energy conversion systems is explored and discussed. We also discuss recent applications of photonic-plasmonic-based biosensors in the rapid management of infectious diseases at point-of-care as well as terahertz biosensing and imaging for improving global health. Finally, we discuss the current challenges and future prospects associated with the existing solar energy conversion and biosensing systems.

From radiometry to chronology of a marine sediment core: A 210Pb dating interlaboratory comparison exercise organised by the IAEA

Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and ²¹⁰Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of ²¹⁰Pb sediment dating technique within the framework of the IAEA Coordinated Research Project. The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable ²¹⁰Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation. The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing ²¹⁰Pb dating methods and identified some limitations in providing reliable chronologies.

Antimicrobial stewardship in care homes: outcomes of importance to stakeholders

BACKGROUND

Heterogeneity of outcomes measured in trials to improve antimicrobial stewardship (AMS) in care homes has compromised quality of evidence. A core outcome set (COS) is needed to facilitate interpretation and synthesis of evidence in this area.

AIM

To determine outcomes deemed important by relevant stakeholders for interventions aimed at improving AMS in care homes, and to produce a refined list of outcomes that could be considered for use in future research.

METHODS

Semi-structured face-to-face or telephone interviews were conducted with key stakeholders. Outcomes reported in previous randomized controlled trials (RCTs) of AMS in care homes were included in a topic guide for interviews. Content analysis was undertaken to identify potential outcomes suggested by participants, followed by further review.

FINDINGS

Twenty-seven outcomes reported in RCTs were refined into a list of 12 overarching outcomes. Interviews with participants (six researchers, 31 healthcare professionals, and four family members of care home residents) identified 40 additional outcomes that were important to them. From these 52 outcomes, the total number of antimicrobials, the appropriateness of antimicrobial prescribing and adherence to guidelines were highlighted by most participants. After reviewing all 52 outcomes, a refined list of 14 outcomes potentially feasible for use in AMS trials in care homes was generated.

CONCLUSION

s: A number of potential outcomes for AMS in care homes, some of which had not been reported in previous studies, were identified. The refined list of 14 outcomes will be used in a future study to agree a COS for care home AMS trials.

Platelet Factor 4 as a Novel Exosome Marker in MALDI-MS Analysis of Exosomes from Human Serum

Exosomes are nanosized vesicles commonly found in biological fluids as a result of a secretion process involving endosomes and multivesicular bodies. The isolation and analysis of exosomes can be useful for noninvasive clinical diagnosis of a variety of human diseases. We investigated the utility of analyzing exosomal proteins, using matrix-assisted laser desorption/ionization combined with Fourier-transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS), as a means of determining the presence of exosomes. MALDI-FTICR-MS analyses of exosomes enriched from human serum via centrifugation in a mass range of m/z 1000-20 000 yielded a distinctive protein around m/z 7766. The high mass accuracy and resolution of MALDI-FTICR-MS allowed for reliable comparisons against a protein database, through which the protein was identified as platelet factor 4 (PLF4), whose singly charged protein peak has an elemental composition of C₃₄₁H₅₇₇N₉₆O₁₀₁S₄⁺, with a theoretical most abundant isotopic peak at m/z 7765.194 and a theoretical average peak at m/z 7766. The MALDI-TOF MS analysis of exosomes from the serum of 27 patients with different states of liver diseases provided the most abundant PLF4 peak for each mass spectrum, along with several additional minor peaks. In conclusion, MALDI-MS is suitable as an alternative exosome detection method, serving as a valuable confirmation tool, greatly decreasing the time and workload associated with exosome identification.

Effects of Matrices and Additives on Multiple Charge Formation of Proteins in MALDI-MS Analysis

The sinapinic acid (SA) matrix has frequently been used for protein analysis in matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). However, the SA matrix does not result in the formation of distinctive multiple protein charge states, whereas the 2-nitrophloroglucinol (2-NPG) matrix is capable of this. The formation of multiple charge states in the MALDI-MS analysis of proteins is advantageous in that it results in higher accuracy. In this study, the mass spectra of several common standard proteins, namely cytochrome c, myoglobin, bovine serum albumin (BSA), and immunoglobulin G (IgG), were compared using various matrices (2,5-dihydroxybenzoic acid, α-cyano-hydroxycinnamic acid, SA, and 2-NPG). Furthermore, the mass spectra of two large standard proteins (BSA and IgG) using various acid additives (H₃PO₄, HNO₃, H₂SO₄, HCl, and trifluoroacetic acid) with the 2-NPG matrix were also compared. Among the different matrices, 2-NPG provided the broadest range of multiple protein charge states, while, among the different additives, the 2-NPG matrix in combination with HCl generated the broadest multiple charge states as well as the most intense protein peaks.

Driving a Superconductor to Insulator Transition with Random Gauge Fields

Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition. The critical disorder depends on interisland coupling in agreement with recent Quantum Monte Carlo simulations. We discuss how this disorder tuned SIT differs from the common frustration tuned SIT that also occurs in magnetic fields. Its discovery enables new high fidelity comparisons between theoretical and experimental studies of disorder effects on quantum critical systems.

Interfacial Engineering of Semiconductor-Superconductor Junctions for High Performance Micro-Coolers

The control of electronic and thermal transport through material interfaces is crucial for numerous micro and nanoelectronics applications and quantum devices. Here we report on the engineering of the electro-thermal properties of semiconductor-superconductor (Sm-S) electronic cooler junctions by a nanoscale insulating tunnel barrier introduced between the Sm and S electrodes. Unexpectedly, such an interface barrier does not increase the junction resistance but strongly reduces the detrimental sub-gap leakage current. These features are key to achieving high cooling power tunnel junction refrigerators, and we demonstrate unparalleled performance in silicon-based Sm-S electron cooler devices with orders of magnitudes improvement in the cooling power in comparison to previous works. By adapting the junctions in strain-engineered silicon coolers we also demonstrate efficient electron temperature reduction from 300 mK to below 100 mK. Investigations on junctions with different interface quality indicate that the previously unexplained sub-gap leakage current is strongly influenced by the Sm-S interface states. These states often dictate the junction electrical resistance through the well-known Fermi level pinning effect and, therefore, superconductivity could be generally used to probe and optimize metal-semiconductor contact behaviour.

Creation and study of triterpenoid nanoparticles and radioprotective substance genistein

This work is devoted to the study and obtaining of new radioprotective agents based on natural flavonoid genistein and spherical amorphous nanoparticles (SANPs) produced from a mixture of birch bark triterpenoids. The physicochemical characteristics of the nanoparticles were studied by electron microscopy, dynamic light scattering, and UV-VIS spectroscopy. The radioprotective efficacy of the nanodrug in vivo and the possibility of its use as a radioprotective agent was shown.

Reduced turn-around time for Mycobacterium tuberculosis drug susceptibility testing with a proportional agar microplate assay

Multidrug-resistant tuberculosis is a major issue worldwide; however, accessibility to drug susceptibility testing (DST) is still limited in developing countries, owing to high costs and complexity. We developed a proportion method on 12-well microplates for DST. The assay reduced the time to results to <12 days and <10 days when bacterial growth was checked with the naked eye or a microscope, respectively. Comparison with the Canetti-Grosset method showed that the results of the two assays almost overlapped (kappa index 0.98 (95% CI 0.91-1.00) for isoniazid, rifampicin, streptomycin; and kappa index 0.92 (95% CI 0.85-0.99) for ethambutol). The sequencing of genes involved in drug resistance showed similar level of phenotype-genotype agreement between techniques. Finally, measurement of the MICs of rifampicin and ethambutol suggests that the currently used critical ethambutol concentration should be revised, and that the current molecular drug susceptibility tests for rifampicin need to be re-evaluated, as in vitro rifampicin-sensitive isolates could harbour drug resistance-associated mutation(s).

[Creation and Study of Triterpenoid Nanoparticles and Amphiphilic meso-Arylporphyrins]

This work is devoted to the study of nanoparticles based on amphiphilic meso-arylporphyrins and spherical amorphous nanoparticles (SANp), consisting of birch bark triterpenoids mixture. Nanoparticles were investigated by electron microscopy, dynamic light scattering, UV spectroscopy and fluorimetry. It was shown the efficiency of the inclusion of porphyrin sensitizer to the nanoparticles and the use of these nanoparticles as drug delivery system.

Control of metamorphic buffer structure and device performance of In(x)Ga(1-x)As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique's precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10(6) cm(-2)), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance-voltage responses with small frequency dispersion. A promising interface trap density of 3 × 10(12) eV(-1) cm(-2) in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems.

Observation of giant positive magnetoresistance in a Cooper pair insulator

Ultrathin amorphous Bi films, patterned with a nanohoneycomb array of holes, can exhibit an insulating phase with transport dominated by the incoherent motion of Cooper pairs (CP) of electrons between localized states. Here, we show that the magnetoresistance (MR) of this Cooper pair insulator (CPI) phase is positive and grows exponentially with decreasing temperature T, for T well below the pair formation temperature. It peaks at a field estimated to be sufficient to break the pairs and then decreases monotonically into a regime in which the film resistance assumes the T dependence appropriate for weakly localized single electron transport. We discuss how these results support proposals that the large MR peaks in other unpatterned, ultrathin film systems disclose a CPI phase and provide new insight into the CP localization.

The effect of sol–gel-formed calcium phosphate coatings on bone ingrowth and osteoconductivity of porous-surfaced Ti alloy implants

Ti-6Al-4V implants formed with a sintered porous surface for implant fixation by bone ingrowth were prepared with or without the addition of a thin surface layer of calcium phosphate (Ca-P) formed using a sol-gel coating technique over the porous surface. The implants were placed transversely across the tibiae of 17 rabbits. Implanted sites were allowed to heal for 2 weeks, after which specimens were retrieved for morphometric assessment using backscattered scanning electron microscopy and quantitative image analysis. Bone formation along the porous-structured implant surface, was measured in relation to the medial and lateral cortices as an indication of implant surface osteoconductivity. The Absolute Contact Length measurements of endosteal bone growth along the porous-surfaced zone were greater with the Ca-P-coated implants compared to the non-Ca-P-coated implants. The Ca-P-coated implants also displayed a trend towards a significant increase in the area of bone ingrowth (Bone Ingrowth Fraction). Finally, there was significantly greater bone-to-implant contact within the sinter neck regions of the Ca-P-coated implants.

Effect of chronic fluoxetine and WAY-100635 treatment on serotonergic neurotransmission in the frontal cortex

Clinical augmentation strategies have shown that some improvement in antidepressant efficacy can be achieved by combining the beta-adrenergic/serotonin (5-HT)1A/1B receptor antagonist (+/-)pindolol with a selective serotonin reuptake inhibitor (SSRI). This has lead to the hypothesis that a combination of a 5-HT1A receptor antagonist with an SSRI will lead to a faster onset of antidepressant action. Although there is a significant accumulation of acute preclinical data supporting this rationale, until recently, there have been no investigations examining the chronic effects of combining an SSRI with a 5-HT1A receptor antagonist. Here, we determined the chronic effects of fluoxetine (10 mg/kg o.d.), administered in combination with the selective 5-HT1A receptor antagonist WAY-100635 (1 mg/kg b.i.d.), on serotonergic neurotransmission in the frontal cortex using in-vivo microdialysis. Following chronic administration of fluoxetine +/- WAY-100635, functional changes in serotonergic neurotransmission, as well as 5-HT1A autoreceptors, were assessed by administering fluoxetine or (+/-) 8-hydroxy-2-(di-n-propylamino)tetralin [(+/-) 8-OH-DPAT] 24 h after the last chronic dose. Chronic administration of WAY-100635 alone produced no detectable change in the functional status of the 5-HT1A receptor. However, fluoxetine alone produced a time-dependent adaptation in serotonergic transmission such that fluoxetine (acutely administered on day 15) was able to produce a two-fold increase in extracellular 5-HT levels but the decrease in response to 8-OH-DPAT was completely attenuated. These data indicate that the fluoxetine-induced adaptation was mediated by desensitization of the 5-HT1A receptor. WAY-100635 given chronically in combination with fluoxetine blocked the SSRI-induced desensitization of the 5-HT1A receptor. Furthermore, chronic treatment with this combination produced no tolerance in terms of its ability to acutely increase forebrain 5-HT levels. These data suggest that augmentation of an SSRI by combined pharmacotherapy with a 5-HT1A antagonist would be effective upon prolonged exposure.

The 5-HT(6) receptor antagonist SB-271046 selectively enhances excitatory neurotransmission in the rat frontal cortex and hippocampus

Preclinical evidence has suggested a possible role for the 5-HT(6) receptor in the treatment of cognitive dysfunction. However, currently there is little neurochemical evidence suggesting the mechanism(s) which may be involved. Using the selective 5-HT(6) antagonist SB-271046 and in vivo microdialysis, we have evaluated the effects of this compound on the modulation of basal neurotransmitter release within multiple brain regions of the freely moving rat. SB-271046 produced no change in basal levels of dopamine (DA), norepinephrine (NE) or 5-HT in the striatum, frontal cortex, dorsal hippocampus or nucleus accumbens. Similarly, this compound had no effect on excitatory neurotransmission in the striatum or nucleus accumbens. Conversely, SB-271046 produced 3- and 2-fold increases in extracellular glutamate levels in both frontal cortex and dorsal hippocampus, respectively. These effects were completely attenuated by infusion of tetrodotoxin but unaffected by the muscarinic antagonist, atropine. Here we demonstrate for the first time the selective enhancement of excitatory neurotransmission by SB-271046 in those brain regions implicated in cognitive and memory function, and provide mechanistic evidence in support of a possible therapeutic role for 5-HT(6) receptor antagonists in the treatment of cognitive and memory dysfunction.

Calcium signaling inhibits interleukin-12 production and activates CD83(+) dendritic cells that induce Th2 cell development

Mature dendritic cells (DCs), in addition to providing costimulation, can define the Th1, in contrast to the Th2, nature of a T-cell response through the production of cytokines and chemokines. Because calcium signaling alone causes rapid DC maturation of both normal and transformed myeloid cells, it was evaluated whether calcium-mobilized DCs polarize T cells toward a Th1 or a Th2 phenotype. After human monocytes were cultured for 24 hours in serum-free medium and granulocyte-macrophage colony-stimulating factor to produce immature DCs, additional overnight culture with either calcium ionophore (CI) or interferon gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and soluble CD40L resulted in phenotypically mature DCs that produced interleukin-8 (IL-8) and displayed marked expression of CD80, CD86, CD40, CD54, CD83, DC-LAMP, and RelB. DCs matured by IFN-gamma, TNF-alpha, and soluble CD40L were additionally distinguished by undetectable CD4 expression, marked secretion of IL-12, IL-6, and MIP-1beta, and preferential ability to promote Th1/Tc1 characteristics during T-cell sensitization. In contrast, DCs matured by CI treatment were distinguished by CD4 expression, modest or absent levels of IL-12, IL-6, and MIP-1beta, and preferential ability to promote Th2/Tc2 characteristics. Calcium signaling selectively antagonized IL-12 production by mature DCs activated with IFN-gamma, TNF-alpha, and soluble CD40L. Although the activation of DCs by calcium signals is largely mediated through calcineurin phosphatase, the inhibition of IL-12 production by calcium signaling was independent of this enzyme. Naturally occurring calcium fluxes in immature DCs, therefore, negatively regulate Dc1 differentiation while promoting Dc2 characteristics and Th2/Tc2 polarization. Calcium-mobilized DCs may have clinical usefulness in treating disease states with excessive Th1/Tc1 activity, such as graft-versus-host disease or autoimmunity.

Effects of chronic fluoxetine treatment in the presence and absence of (+/-)pindolol: a microdialysis study

Using in vivo microdialysis in the frontal cortex of the freely moving rat we evaluated the effects of chronic treatment with the serotonin specific reuptake inhibitor (SSRI) fluoxetine in the presence and absence of the 5-HT(1A)/beta-adrenergic antagonist (+/-)pindolol. Chronic vehicle treated animals produced no significant response to a challenge with fluoxetine (10 mg kg(-1)) on day 8 and 15. Alternatively, a significant (P<0.05) decrease in extracellular 5-HT was observed in control animals upon challenge with the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.03 and 0.1 mg kg(-1)). Conversely, animals treated with fluoxetine (10 mg kg(-1) o.d.) for 7 and 14 days produced a significant (P<0.05) 2 fold increase in extracellular 5-HT when challenged with fluoxetine (10 mg kg(-1)) on day 8 and 15. Moreover, no significant decrease in extracellular 5-HT was observed upon challenge with either dose of 8-OH-DPAT. Animals chronically treated with (+/-)pindolol (10 or 20 mg kg(-1) b.i.d.) produced a significant dose-related increase in extracellular 5-HT upon challenge with fluoxetine on day 15 only. Furthermore, both doses produced a significantly blunted response to the low dose challenge of 8-OH-DPAT (0.03 mg kg(-1)). In addition, 20 mg kg(-1) (+/-)pindolol treated animals also had no response to the higher 0.1 mg kg(-1) dose of 8-OH-DPAT. Animals treated for 14 days with a combination of (+/-)pindolol (10 or 20 mg kg(-1)) and fluoxetine were not significantly different from vehicle treated animals when challenged with fluoxetine or 8-OH-DPAT. Taken together it would therefore appear that although (+/-)pindolol alone has sufficient intrinsic activity to produce a desensitization of the 5-HT(1A) receptor, when given in combination with fluoxetine it is able to prevent the desensitization induced by not only fluoxetine but also itself. This may suggest that the clinical augmentation of antidepressant action by pindolol, when co-administered with a SSRI, is via antagonism of the 5-HT(1A) receptor.

Granulocyte-macrophage colony-stimulating factor, interleukin-2, and interleukin-12 synergize with calcium ionophore to enhance dendritic cell function

The authors previously showed that monocytes treated with calcium ionophore (CI) acquire characteristics of mature dendritic cells (DC) in part through a calcineurin-dependent pathway. In this study, the authors evaluated the ability of granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-2 (IL-2), and interleukin-12 (IL-12) alone or in combination with CI to induce DC characteristics in peripheral blood monocytes. Monocytes obtained by leukapheresis and countercurrent centrifugal elutriation were cultured with calcium, cytokines, or both, profiled by flow cytometry, and assessed for antigen uptake and sensitization of autologous CD8+ T cells to antigen. Monocytes treated with the combination of GM-CSF, IL-2, and IL-12 resulted in immunophenotypic and antigen uptake profiles typical of immature DC, including loss of surface CD14 expression, de novo low-level expression of B7.1, negligible CD83 expression, marked enhancement of CD40 and ICAM-1, and high major histocompatibility complex class I and II levels. A high level of antigen uptake by macro-pinocytosis was observed. In contrast, CI treatment significantly up-regulates B7.1, B7.2, CD40, CD54, and CD83 and substantially down-regulates CD14 and macro-pinocytosis, a profile consistent with mature DC. Many CI-induced modulations, but none resulting from cytokine treatment alone, were inhibited by the calcineurin phosphatase inhibitor cyclosporin A. Compared with monocytes treated with CI alone, combined treatment of monocytes with GM-CSF, IL-2, IL-12, and CI augmented B7.1 and CD83 expression and enhanced sensitization of autologous CD8+ T cells to melanoma-antigen-derived peptides. These results suggest that several independent pathways of DC activation can cooperatively enhance the function of monocyte-derived DC.

In vivo effects of the 5-HT(6) antagonist SB-271046 on striatal and frontal cortex extracellular concentrations of noradrenaline, dopamine, 5-HT, glutamate and aspartate

Although the 5-HT(6) receptor subtype was identified some 5 years ago, very little is known about its function within the brain. Here we demonstrate, for the first time, the neurochemical effects of a selective 5-HT(6) receptor ligand. Using in vivo microdialysis in the freely moving rat, we evaluated the effects of the selective 5-HT(6) receptor antagonist SB-271046 by simultaneous measurement of 5-hydroxytryptamine (5-HT), dopamine (DA), noradrenaline (NA), glutamate and aspartate from the striatum and frontal cortex. SB-271046 did not alter basal levels of 5-HT, DA and NA in either brain region. Similarly, there was no change basal levels of either of the excitatory amino acids within the striatum. In contrast, administration of SB-271046 (10 mg kg(-1) s.c.) produced a significant (P<0.05), tetrodotoxin-dependent, increase in extracellular levels of both glutamate and aspartate within the frontal cortex, reaching maximum values of 375.4+/-82.3 and 215. 3+/-62.1% of preinjection values, respectively.

The role of 5-HT(1A) and 5-HT(1B/1D) receptors on the modulation of acute fluoxetine-induced changes in extracellular 5-HT: the mechanism of action of (+/-)pindolol

Some clinical evidence has suggested that (+/-)pindolol can be effective at producing a shortened time to onset of antidepressant activity when co-administered with a serotonin specific reuptake inhibitor (SSRI). This effect has been attributed to the antagonist effects of pindolol at the 5-HT(1A) receptor. In the present study, we compared the pharmacology of (+/-)pindolol, WAY-100635 (a 5-HT(1A) antagonist), GR127935 (a 5-HT(1B/1D) antagonist), and isamoltane (a 5-HT(1B) antagonist), when given acutely in combination with fluoxetine, using in vivo microdialysis in the frontal cortex of the freely moving rat. We have determined that the acute fluoxetine-induced increases in extracellular 5-HT can be augmented by (+/-)pindolol, WAY100635, GR127935 and isamoltane with maximum increases of 216+/-32%, 235+/-49%, 240+/-18% and 171+/-47% of preinjection control levels, respectively. Combination of both 5-HT(1A) and 5-HT(1B/1D) autoreceptor antagonists with fluoxetine produced additive increases in extracellular 5-HT (i.e. WAY100635+GR127935+fluoxetine and WAY100635+isamoltane+fluoxetine produced a four- and five-fold potentiation, respectively), suggesting that this strategy may be useful in further augmenting the action of a SSRI in the treatment of depression. In addition, by comparing the combined administration of (+/-)pindolol with either WAY100635, GR127935 or isamoltane, we have determined that (+/-)pindolol produces much of its acute potentiation of fluoxetine-induced increases in extracellular 5-HT via its action at the 5-HT(1B/D) receptor in addition to any activity it has at the presynaptic 5-HT(1A) receptor.

Active macromolecule uptake by lymph node antigen-presenting cells: a novel mechanism in determining sentinel lymph node status

BACKGROUND

Although sentinel lymph node (SLN) biopsy is a powerful staging tool for patients with melanoma and breast cancer, controversy remains regarding specific aspects of technique. We examined particle uptake by antigen-presenting cells (APCs) to determine if this mechanism is responsible for the differential retention of radioactivity in SLNs relative to nonsentinel lymph nodes (NSLNs).

METHODS

Mapping was conducted in pigs injected with vital blue dye, fluoroscein isothiocyanate-labeled human serum albumin (FITC-HSA), and one of two 99mtechnetium-labeled tracers, i.e., human serum albumin, a small macromolecule, or unfiltered sulfur colloid, a mixture of small and large particles. Macromolecule uptake by APCs was studied in vitro by using FITC-HSA and measured by fluorescence-activated cell sorting (FACS). SLNs and NSLNs were analyzed by fluorescence microscopy or FACS, with counterstaining for leukocyte cell surface markers.

RESULTS

Both radiotracers were effective. Cultured APCs rapidly took up FITC-HSA. Microscopy showed FITC-HSA in the subcapsular sinus of SLNs shortly after injection and subsequent distribution to interfollicular areas. FACS revealed increasing amounts of FITC-HSA in SLNs over time. Cells responsible for uptake were APCs, expressing major histocompatibility (locus) class II.

CONCLUSIONS

This report establishes active macromolecule uptake as a mechanism that determines SLN status. This mechanism has important implications for performing SLN biopsy.

In vivo resistance of coronally induced bacterial ingress by an experimental glass ionomer cement root canal sealer

The resistance of an experimental sealer (KT-308) to bacterial ingress was assessed in six beagle dogs. In four mandibular premolars per dog, canals were prepared, filled with condensed gutta-percha and either KT-308 or Roth 801 cement (n = 24 roots), and the pulp chambers inoculated with plaque. Two additional premolars per dog were similarly root-filled, but not inoculated (n = 12 and 11, respectively). One incisor per dog was inoculated, but not root-filled (n = 6). Dogs were terminated after 6 months, and jaw blocks were retrieved and processed for light microscopic examination of the periapical tissues. Inflammation about the inoculated roots was significantly lower (p < 0.03) for KT-308 (17%) than Roth 801 cement (46%). Inflammation about the noninoculated roots did not differ significantly between KT-308 (8%) and Roth 801 cement (36%). This study demonstrated a better functional efficacy of KT-308 than of Roth 801 cement, and validated this in vivo model for assessment of root filling materials.

Isolated hepatic perfusion for lapine liver metastases: impact of hyperthermia on permeability of tumor neovasculature

BACKGROUND

Hyperthermic isolated hepatic perfusion (IHP) has been shown to cause significant regression of advanced unresectable liver metastases in patients. Although there are different agents and treatment modalities used in IHP, the contribution of perfusion hyperthermia is unknown.

PURPOSE

A large animal model of unresectable liver metastases and a technical standard for IHP in this model were established. This model was used to assess the effects of hyperthermia on vascular permeability of tumors and normal liver tissue during IHP.

METHODS

Sixty-five New Zealand White rabbits were used in a series of experiments. Disseminated liver tumors were established by direct injection of 1 x 10(6) VX-2 cells into the portal vein by laparotomy in anesthetized animals. Several surgical perfusion techniques were explored to determine a reliable and reproducible IHP model. Vascular permeability in tumor versus liver was then assessed with Evan's Blue labeled bovine albumin under normothermic (tissue temperature 36.5 degrees C +/- 0.5 degree C), moderate hyperthermic (39 degrees C +/- 0.5 degree C), or severe hyperthermic (41 degrees C +/- 0.5 degree C) conditions.

RESULTS

Tumor model and perfusion techniques were successfully established with inflow through the portal vein and outflow through an isolated segment of the inferior vena cava. A gravity driven perfusion circuit with stable perfusion parameters and complete vascular isolation was used. Vascular permeability was higher in tumor than in normal tissues (P = .03) at all time points during IHP. Hyperthermia resulted in a significant (up to 5-fold) increase in permeability of neovasculature; when severe hyperthermia was used, tumor vascular permeability was increased even more than normal liver permeability (P = .01).

CONCLUSIONS

The VX-2/New Zealand White rabbit system can be used as a reproducible large-animal model for IHP of unresectable liver metastases. It can be used to characterize the contribution and mechanism of action of different treatment parameters used in IHP. Hyperthermia preferentially increases vascular permeability in tumors compared with liver tissue in a dose-dependent fashion, thus providing a mechanism for its presumed benefit during isolated organ perfusion.

Isolated hepatic perfusion for lapine liver metastases: impact of hyperthermia on permeability of tumor neovasculature

BACKGROUND

Hyperthermic isolated hepatic perfusion (IHP) has been shown to cause significant regression of advanced unresectable liver metastases in patients. Although there are different agents and treatment modalities used in IHP, the contribution of perfusion hyperthermia is unknown.

PURPOSE

A large animal model of unresectable liver metastases and a technical standard for IHP in this model were established. This model was used to assess the effects of hyperthermia on vascular permeability of tumors and normal liver tissue during IHP.

METHODS

Sixty-five New Zealand White rabbits were used in a series of experiments. Disseminated liver tumors were established by direct injection of 1 x 10(6) VX-2 cells into the portal vein by laparotomy in anesthetized animals. Several surgical perfusion techniques were explored to determine a reliable and reproducible IHP model. Vascular permeability in tumor versus liver was then assessed with Evan's Blue labeled bovine albumin under normothermic (tissue temperature 36.5 degrees C +/- 0.5 degree C), moderate hyperthermic (39 degrees C +/- 0.5 degree C), or severe hyperthermic (41 degrees C +/- 0.5 degree C) conditions.

RESULTS

Tumor model and perfusion techniques were successfully established with inflow through the portal vein and outflow through an isolated segment of the inferior vena cava. A gravity driven perfusion circuit with stable perfusion parameters and complete vascular isolation was used. Vascular permeability was higher in tumor than in normal tissues (P = .03) at all time points during IHP. Hyperthermia resulted in a significant (up to 5-fold) increase in permeability of neovasculature; when severe hyperthermia was used, tumor vascular permeability was increased even more than normal liver permeability (P = .01).

CONCLUSIONS

The VX-2/New Zealand White rabbit system can be used as a reproducible large-animal model for IHP of unresectable liver metastases. It can be used to characterize the contribution and mechanism of action of different treatment parameters used in IHP. Hyperthermia preferentially increases vascular permeability in tumors compared with liver tissue in a dose-dependent fashion, thus providing a mechanism for its presumed benefit during isolated organ perfusion.

Effects of venlafaxine on extracellular concentrations of 5-HT and noradrenaline in the rat frontal cortex: augmentation via 5-HT1A receptor antagonism

Venlafaxine is a novel serotonin/noradrenaline reuptake inhibitor (SNRI) which has been shown clinically to be an effective antidepressant (AD) with a faster onset of action than serotonin specific reuptake inhibitors (SSRI). Preclinically, venlafaxine has been shown to potently inhibit dorsal raphe neuronal (DRN) firing through a 5-HT1A mediated mechanism, in a similar manner to SSRIs. Here we demonstrate the acute neurochemical effects of venlafaxine on extracellular concentrations of 5-HT and noradrenaline (NA) from the rat frontal cortex using in vivo microdialysis. Administration of venlafaxine (3-50 mg/kg s.c.) resulted in a significant dose-dependent increase in extracellular NA, but produced no significant increase in 5-HT concentrations. Combination treatment with the selective 5-HT1A antagonist WAY100635 produced a dose-dependent augmentation of venlafaxine-induced (3-30 mg/kg s.c) extracellular 5-HT concentrations, but had no further effect on NA above that produced by venlafaxine alone. WAY100635, at doses as low as 0.03 mg/kg s.c., maintained this potentiation effect. The beta-adrenergic/5-HT1A receptor antagonist (+/-)pindolol and the selective 5-HT1B/D antagonist GR127935 produced no significant augmentation of venlafaxine-induced changes in either 5-HT or NA. Using the alpha1 and alpha2-adrenoceptor antagonists, prazosin and idazoxane, we also demonstrate the role of the alpha-adrenoceptors in the augmentation of venlafaxine-induced changes. The possible mechanisms underlying venlafaxines improved clinical AD action and the potential for further enhancement of this SNRIs clinical effects are discussed.

Susceptibility of Nd:YAG laser-irradiated root surfaces in replanted teeth to external inflammatory resorption

Nd:YAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2 x 3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n = 12 roots) and 3 (n = 4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 pps, 300 microns tip, 20 s). In Groups 2 (n = 12) and 4 (n = 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfusion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 microns) at 180-microns intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P < 0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in Nd:YAG laser-irradiated dentin. Therefore, the clinical application of Nd:YAG laser to the root surfaces of replanted teeth is not warranted.

Information technologies for Marine Corps combat medicine

Future Marine Corps warfighting concepts will make it more difficult to locate casualties, which will complicate casualty evacuation, lengthen casualty wait times, and require infantrymen or corpsmen to provide more extensive treatment. In these future scenarios, information flow and communications will be critical to medical functions. We asked, for Navy medical support to the Marines, what information will future combat medicine require and what technologies should supply those information needs? Based on analyses of patient data streams, focus groups of Navy medical personnel, and our estimates of the cost and feasibility of communications systems, we recommend the following: (1) increase medical training for some fraction of Marines, especially in hemorrhage control; (2) augment corpsmen's training; (3) furnish data systems for evacuation and supply that would provide in-transit visibility and simplify requests; (4) provide all ground medical personnel with access to treatment information systems and limited voice communications; and (5) exploit e-mail systems to reduce reliance on voice communications. Implementation time frames are discussed.

Lower-extremity saphenous vein transposition arteriovenous fistula: an alternative for hemodialysis access in AIDS patients

Arteriovenous access for long-term hemodialysis in patients with the acquired immunodeficiency syndrome (AIDS) represents a special challenge. Many of these patients are chronic intravenous drug abusers and do not have patent superficial upper-extremity veins available for conventional arteriovenous fistulas. This group of patients is also particularly prone to infections, which contraindicates the use of prosthetic grafts. Over a period of 13 months, five lower-extremity saphenous vein transposition arteriovenous fistulas (SVTAFs) were performed. Four patients had a diagnosis of AIDS at the time of operation; all of these were intravenous drug abusers. Three patients were male, two were female, and their age ranged from 34 to 66 years (mean, 48). Three patients had a SVTAF as their first hemodialysis access, and in two it was performed after multiple failed upper-extremity accesses. Four fistulas remain patent to date, after a mean follow-up of 11 months (range, 4 weeks to 16 months). One fistula thrombosed 4 weeks postoperatively, due to a hematoma that occurred after premature venipuncture for dialysis. There were no other major complications. We conclude that SVTAF is a suitable alternative to the limited hemodialysis venous access sites, especially in the AIDS population.

Effects of 5-HT1A receptor antagonists on fluoxetine-induced changes in extracellular serotonin concentrations in rat frontal cortex

Clinical studies in which serotonin specific reuptake inhibitors have been co-administered with pindolol have demonstrated a shortened time to onset of antidepressant activity. This effect has been attributed to the antagonist effects of pindolol at the presynaptic 5-HT1A receptor which augments the action of the serotonin specific reuptake inhibitors. In the present study, we demonstrate that acute fluoxetine-induced increases in extracellular serotonin concentrations, as measured by microdialysis in the frontal cortex, can be potentiated by 5-HT1A receptor blockade using N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(pyridinyl)cyclohexa necarboxamide (WAY100635), the silent and selective 5-HT1A receptor antagonist. WAY100635 at doses as low as 0.03 mg/kg s.c. maintained this potentiation effect across a range of fluoxetine doses. In addition, using antagonists with different intrinsic agonist activities for the 5-HT1A receptor, we have determined that only compounds with very low intrinsic agonist activity can produce a potentiation of the acute fluoxetine-induced increases in extracellular serotonin.

Apical extent of rotary canal instrumentation with an apex-locating handpiece in vitro

PROBLEM

The Tri Auto ZX (J. Morita Co., Kyoto, Japan) is a cordless endodontic handpiece with a built-in apex locator that is programmed to reverse the direction of rotation when the file reaches a predetermined apical level or when torque becomes excessive.

OBJECTIVE

The purpose of this investigation was to examine the apical extent of rotary canal instrumentation and the ability to maintain apical constriction with the Tri Auto ZX at different automated settings.

STUDY DESIGN

In 60 extracted teeth, canals were measured to the apical constriction, first visually and then electronically with the Tri Auto ZX; then they were instrumented with nickel titanium rotary files. For the instrumentation, the automatic apical reverse mechanism of the handpiece was set to 1, 1.5, or 2; these settings correspond to different distances from the apical foramen. Instrumentation was carried out apically until rotation was reversed by the automatic apical reverse function; the instrumented length was then measured, and the canal was filled with gutta-percha and sealer. The integrity of the apical constriction was assessed by exposing the apical 4 mm of the canal and observing the dentin-cementum junction. Paired t-tests were used to compare the visually measured length, the electronically measured length, and the instrumented length for each tooth.

RESULTS

On average, the electronically measured length was 0.54 mm shorter than the visually measured length (p < 0.05). When the automatic apical reverse mechanism's setting was 1, the instrumented length was 0.1 mm shorter than the electronically measured length; when the setting was 1.5, the instrumented length was 0.36 mm shorter than the electronically measured length (p < 0.01). Results were inconsistent when the setting was 2.

CONCLUSION

Instrumentation with the automatic apical reverse feature set at 1 consistently approximated the apical constriction; however, the constriction was frequently enlarged.

Osteoprotegerin: a novel secreted protein involved in the regulation of bone density

A novel secreted glycoprotein that regulates bone resorption has been identified. The protein, termed Osteoprotegerin (OPG), is a novel member of the TNF receptor superfamily. In vivo, hepatic expression of OPG in transgenic mice results in a profound yet nonlethal osteopetrosis, coincident with a decrease in later stages of osteoclast differentiation. These same effects are observed upon administration of recombinant OPG into normal mice. In vitro, osteoclast differentiation from precursor cells is blocked in a dose-dependent manner by recombinant OPG. Furthermore, OPG blocks ovariectomy-associated bone loss in rats. These data show that OPG can act as a soluble factor in the regulation of bone mass and imply a utility for OPG in the treatment of osteoporosis associated with increased osteoclast activity.

Electronic length measurement using small and large files in enlarged canals

Electronic apex locators are frequently used attached to a small size endodontic file; however, the effect on the measurement of the relative diameters of the file and the root canal has not been clarified. In this study, the length of enlarged canals was measured using small size files and files matching the canal diameter to observe a possible discrepancy. The accuracy of electronic length control during canal preparation with rotary files was also assessed. The root canals in 21 extracted, single rooted teeth were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an alginate mold. The initial canal length (IL) was measured with the Root ZX apex locator by negotiating a size 10 file to the apical constriction. The canal was enlarged to size 60 with rotary files while the length was continuously controlled with the apex locator. Then, the final length measurements were obtained with a size 10 file and a size 60 file (FL-10 and FL-60, respectively). The average values of IL, FL-10 and FL-60 were calculated and compared using Repeated Measures Analysis of Variance followed by Tukey's Studentized Range test (P < 0.05). Using composite resin, the size 60 files were secured at the FL-60 length, the teeth were removed from the alginate mold, stained with Picroformal DI Buoin stain and the position of the file tip was observed histomorphometrically after the apical 4 mm of the canal was exposed by grinding the buccal aspect of the root. The IL was 0.45 mm shorter than AL (P < 0.05). The differences between FL-10, FL-60 and IL were not statistically significant. Histomorphometrically, the apical constriction was absent in all the teeth, but the file tips were confined within the root. This study concluded that the Root ZX indicated the location of an apical constriction even when the anatomic constriction was eliminated. In the enlarged canals, length measurements obtained with small and large size files were comparable.

Spatially resolved phase imaging of a programmable liquid-crystal grating

Phase imaging is used to compare near-field measurements with the corresponding far-field intensity distribution. A liquid-crystal device serves as a phase object that can be programmed as a variable grating. Real-time phase visualization then provides an avenue for direct optimization of complex phase gratings.

Expression of keratinocyte growth factor in embryonic liver of transgenic mice causes changes in epithelial growth and differentiation resulting in polycystic kidneys and other organ malformations

Expression of human keratinocyte growth factor (KGF/FGF-7) was directed to hepatocytes during the later period of mouse gestation using a human apolipoprotein E (ApoE) gene promoter and its associated liver-specific enhancer. Human KGF was detectable in liver extracts and serum prepared from e17.5-e19.5 embryos, concomitant with the appearance of morphological abnormalities in several organs which express KGF receptor. The most striking phenotypic aberration in the ApoE-hKGF transgenic embryos was marked hyperplasia and cystic dilation of the cortical and medullary kidney collecting duct system, a phenotype resembling infantile polycystic kidney disease in humans. Transgenic embryos had enlarged livers, with prominent biliary epithelial hyperplasia, and also exhibited enhanced bronchiolar epithelial and type II pneumocyte proliferation. There was variable hyperplasia of intestinal epithelia, and urothelium of the urinary bladder and ureters. When compared to age-matched littermate controls, marked epidermal papillomatous acanthosis and hyperkeratosis in the skin, with a notable decrease in the number of developing hair follicles was seen in transgenic embryos. The pancreas exhibited significant ductal hyperplasia, with an increase in the number of ductal epithelial cells staining positive for insulin expression. High systemic levels of KGF during the latter stages of embryogenesis causes abnormalities in epithelial growth and differentiation within multiple organ systems and results in perinatal lethality. Correct temporal and spatial expression of KGF during the latter stages of organ development is likely to play a critical role in mesenchymal-epithelial signaling required for normal embryonic growth and development.

A genetic linkage map of mouse chromosome 2 extending from thrombospondin to paired box gene 1, including the H3 minor histocompatibility complex

The classical minor histocompatibility 3 (H3) locus was originally defined by the phenotype of skin graft rejection, which is a complex genetic trait. H3 is now known to be a gene complex comprised of a minimum of two functionally interdependent alloantigen-encoding loci, H3a and H3b. H3a encodes a peptide recognized by cytotoxic T cells, and H3b encodes a peptide that stimulates helper T cells. The H3 complex also contains the beta2-microglobulin gene (B2m), and polymorphisms in B2m contribute to the tissue rejection phenotype. We describe a high-density genetic linkage map of a 16-cM region of mouse Chromosome 2 from thrombospondin (Thbs1) to paired box gene 1 (Pax1). This genetic map includes H3a, H3b, and B2m. Other genes and anonymous loci have also been placed on the map. H3a maps between D2Mit444 and B2m in close vicinity to several known genes. H3b maps 12 cM distal to H3a, and the proprotein convertase subtilisin/kexin type 2 gene (Pcsk2; formerly Nec2) cosegregates with H3b in a high-resolution backcross panel. The H3 complex spans a region that shows conserved synteny to human chromosomes 15q, 2q, and 20p.