Defining imaging biomarker cut points for brain aging and Alzheimer's disease.

INTRODUCTION: Our goal was to develop cut points for amyloid positron emission tomography (PET), tau PET, flouro-deoxyglucose (FDG) PET, and MRI cortical thickness. METHODS: We examined five methods for determining cut points. RESULTS: The reliable worsening method produced a cut point only for amyloid PET. The specificity, sensitivity, and accuracy of cognitively impaired versus young clinically normal (CN) methods labeled the most people abnormal and all gave similar cut points for tau PET, FDG PET, and cortical thickness. Cut points defined using the accuracy of cognitively impaired versus age-matched CN method labeled fewer people abnormal. DISCUSSION: In the future, we will use a single cut point for amyloid PET (standardized uptake value ratio, 1.42; centiloid, 19) based on the reliable worsening cut point method. We will base lenient cut points for tau PET, FDG PET, and cortical thickness on the accuracy of cognitively impaired versus young CN method and base conservative cut points on the accuracy of cognitively impaired versus age-matched CN method.

Comparison of accelerated T1-weighted whole-brain structural-imaging protocols.

Imaging in neuroscience, clinical research and pharmaceutical trials often employs the 3D magnetisation-prepared rapid gradient-echo (MPRAGE) sequence to obtain structural T1-weighted images with high spatial resolution of the human brain. Typical research and clinical routine MPRAGE protocols with ~1mm isotropic resolution require data acquisition time in the range of 5-10min and often use only moderate two-fold acceleration factor for parallel imaging. Recent advances in MRI hardware and acquisition methodology promise improved leverage of the MR signal and more benign artefact properties in particular when employing increased acceleration factors in clinical routine and research. In this study, we examined four variants of a four-fold-accelerated MPRAGE protocol (2D-GRAPPA, CAIPIRINHA, CAIPIRINHA elliptical, and segmented MPRAGE) and compared clinical readings, basic image quality metrics (SNR, CNR), and automated brain tissue segmentation for morphological assessments of brain structures. The results were benchmarked against a widely-used two-fold-accelerated 3T ADNI MPRAGE protocol that served as reference in this study. 22 healthy subjects (age=20-44yrs.) were imaged with all MPRAGE variants in a single session. An experienced reader rated all images of clinically useful image quality. CAIPIRINHA MPRAGE scans were perceived on average to be of identical value for reading as the reference ADNI-2 protocol. SNR and CNR measurements exhibited the theoretically expected performance at the four-fold acceleration. The results of this study demonstrate that the four-fold accelerated protocols introduce systematic biases in the segmentation results of some brain structures compared to the reference ADNI-2 protocol. Furthermore, results suggest that the increased noise levels in the accelerated protocols play an important role in introducing these biases, at least under the present study conditions.

Different definitions of neurodegeneration produce similar amyloid/neurodegeneration biomarker group findings.

We recently demonstrated that the frequencies of biomarker groups defined by the presence or absence of both amyloidosis (A+) and neurodegeneration (N+) changed dramatically by age in cognitively non-impaired subjects. Our present objectives were to assess the consequences of defining neurodegeneration in five different ways on the frequency of subjects classified as N+, on the demographic associations with N+, and on amyloidosis and neurodegeneration (A/N) biomarker group frequencies by age. This was a largely cross-sectional observational study of 1331 cognitively non-impaired subjects aged 50-89 drawn from a population-based study of cognitive ageing. We assessed demographic associations with N+, and A/N biomarker group frequencies by age where A+ was defined by amyloid PET and N+ was defined in five different ways: (i) abnormal adjusted hippocampal volume alone; (ii) abnormal Alzheimer's disease signature cortical thickness alone; (iii) abnormal fluorodeoxyglucose positron emission tomography alone; (iv) abnormal adjusted hippocampal volume or abnormal fluorodeoxyglucose positron emission tomography; and (v) abnormal Alzheimer's disease signature cortical thickness or abnormal fluorodeoxyglucose positron emission tomography. For each N+ definition, participants were assigned to one of four biomarker groups; A-N-, A+N-, A-N+, or A+N+. The three continuous individual neurodegeneration measures were moderately correlated (rs = 0.42 to 0.54) but when classified as normal or abnormal had only weak agreement (κ = 0.20 to 0.29). The adjusted hippocampal volume alone definition classified the fewest subjects as N+ while the Alzheimer's disease signature cortical thickness or abnormal fluorodeoxyglucose positron emission tomography definition classified the most as N+. Across all N+ definitions, N+ subjects tended to be older, more often male and APOE4 carriers, and performed less well on functional status and learning and memory than N- subjects. For all definitions of neurodegeneration, (i) the frequency of A-N- was 100% at age 50 and declined monotonically thereafter; (ii) the frequency of A+N- increased from age 50 to a maximum in the mid-70s and declined thereafter; and3 (iii) the frequency of A-N+ (suspected non-Alzheimer's pathophysiology) and of A+N+ increased monotonically beginning in the mid-50s and mid-60s, respectively. Overall, different neurodegeneration measures provide similar but not completely redundant information. Despite quantitative differences, the overall qualitative pattern of the A-N-, A+N-, A-N+, and A+N+ biomarker group frequency curves by age were similar across the five different definitions of neurodegeneration. We conclude that grouping subjects by amyloidosis and neurodegeneration status (normal/abnormal) is robust to different imaging definitions of neurodegeneration and thus is a useful way for investigators throughout the field to communicate in a common classification framework.

Complete Chloroplast Genome of an Endophytic Ostreobium sp. (Ostreobiaceae) from the U.S. Virgin Islands.

We present the complete chloroplast genome sequence of an endophytic Ostreobium sp. isolated from a 19th-century coralline red algal specimen from St. Croix, U.S. Virgin Islands. The chloroplast genome is 84,848 bp in length, contains 114 genes, and has a high level of gene synteny to other Ostreobiaceae.

Effects of MRI scan acceleration on brain volume measurement consistency.

PURPOSE: To evaluate the effects of recent advances in magnetic resonance imaging (MRI) radiofrequency (RF) coil and parallel imaging technology on brain volume measurement consistency. MATERIALS AND METHODS: In all, 103 whole-brain MRI volumes were acquired at a clinical 3T MRI, equipped with a 12- and 32-channel head coil, using the T1-weighted protocol as employed in the Alzheimer's Disease Neuroimaging Initiative study with parallel imaging accelerations ranging from 1 to 5. An experienced reader performed qualitative ratings of the images. For quantitative analysis, differences in composite width (CW, a measure of image similarity) and boundary shift integral (BSI, a measure of whole-brain atrophy) were calculated. RESULTS: Intra- and intersession comparisons of CW and BSI measures from scans with equal acceleration demonstrated excellent scan-rescan accuracy, even at the highest acceleration applied. Pairs-of-scans acquired with different accelerations exhibited poor scan-rescan consistency only when differences in the acceleration factor were maximized. A change in the coil hardware between compared scans was found to bias the BSI measure. CONCLUSION: The most important findings are that the accelerated acquisitions appear to be compatible with the assessment of high-quality quantitative information and that for highest scan-rescan accuracy in serial scans the acquisition protocol should be kept as consistent as possible over time.

Development of an antigen detection assay for early point-of-care diagnosis of Zaire ebolavirus.

The 2013-2016 Ebola virus (EBOV) outbreak in West Africa and the ongoing cases in the Democratic Republic of the Congo have spurred development of a number of medical countermeasures, including rapid Ebola diagnostic tests. The likelihood of transmission increases as the disease progresses due to increasing viral load and potential for contact with others. Early diagnosis of EBOV is essential for halting spread of the disease. Polymerase chain reaction assays are the gold standard for diagnosing Ebola virus disease (EVD), however, they rely on infrastructure and trained personnel that are not available in most resource-limited settings. Rapid diagnostic tests that are capable of detecting virus with reliable sensitivity need to be made available for use in austere environments where laboratory testing is not feasible. The goal of this study was to produce candidate lateral flow immunoassay (LFI) prototypes specific to the EBOV glycoprotein and viral matrix protein, both targets known to be present during EVD. The LFI platform utilizes antibody-based technology to capture and detect targets and is well suited to the needs of EVD diagnosis as it can be performed at the point-of-care, requires no cold chain, provides results in less than twenty minutes and is low cost. Monoclonal antibodies were isolated, characterized and evaluated in the LFI platform. Top performing LFI prototypes were selected, further optimized and confirmed for sensitivity with cultured live EBOV and clinical samples from infected non-human primates. Comparison with a commercially available EBOV rapid diagnostic test that received emergency use approval demonstrates that the glycoprotein-specific LFI developed as a part of this study has improved sensitivity. The outcome of this work presents a diagnostic prototype with the potential to enable earlier diagnosis of EVD in clinical settings and provide healthcare workers with a vital tool for reducing the spread of disease during an outbreak.

Aortic Stiffness and White Matter Microstructural Integrity Assessed by Diffusion Tensor Imaging: The ARIC-NCS.

Background Changes in white matter microstructural integrity are detectable before appearance of white matter lesions on magnetic resonance imaging as a manifestation of cerebral small-vessel disease. The information relating poor white matter microstructural integrity to aortic stiffness, a hallmark of aging, is limited. We aimed to examine the association between aortic stiffness and white matter microstructural integrity among older adults. Methods and Results We conducted a cross-sectional study to examine the association between aortic stiffness and white matter microstructural integrity among 1484 men and women (mean age, 76 years) at the 2011 to 2013 examination of the ARIC-NCS (Atherosclerosis Risk in Communities Neurocognitive Study). Aortic stiffness was measured as carotid-femoral pulse wave velocity. Cerebral white matter microstructural integrity was measured as fractional anisotropy and mean diffusivity using diffusion tensor imaging. Multivariable linear regression was used to examine the associations of carotid-femoral pulse wave velocity with fractional anisotropy and mean diffusivity of the overall cerebrum and at regions of interest. Each 1-m/s higher carotid-femoral pulse wave velocity was associated with lower overall fractional anisotropy (ß=-0.03; 95% CI, -0.05 to -0.02) and higher overall mean diffusivity (ß=0.03; 95% CI, 0.02-0.04). High carotid-femoral pulse wave velocity (upper 25th percentile) was associated with lower fractional anisotropy (ß=-0.40; 95% CI, -0.61 to -0.20) and higher overall mean diffusivity (ß=0.27; 95% CI, 0.10-0.43). Similar associations were observed at individual regions of interest. Conclusions High aortic stiffness is associated with low cerebral white matter microstructural integrity among older adults. Aortic stiffness may serve as a target for the prevention of poor cerebral white matter microstructural integrity.

Comparison of amyloid plaque contrast generated by T2-weighted, T2*-weighted, and susceptibility-weighted imaging methods in transgenic mouse models of Alzheimer's disease.

One of the hallmark pathologies of Alzheimer's disease (AD) is amyloid plaque deposition. Plaques appear hypointense on T(2)-weighted and T(2)*-weighted MR images probably due to the presence of endogenous iron, but no quantitative comparison of various imaging techniques has been reported. We estimated the T(1), T(2), T(2)*, and proton density values of cortical plaques and normal cortical tissue and analyzed the plaque contrast generated by a collection of T(2)-weighted, T(2)*-weighted, and susceptibility-weighted imaging (SWI) methods in ex vivo transgenic mouse specimens. The proton density and T(1) values were similar for both cortical plaques and normal cortical tissue. The T(2) and T(2)* values were similar in cortical plaques, which indicates that the iron content of cortical plaques may not be as large as previously thought. Ex vivo plaque contrast was increased compared to a previously reported spin-echo sequence by summing multiple echoes and by performing SWI; however, gradient echo and SWI were found to be impractical for in vivo imaging due to susceptibility interface-related signal loss in the cortex.

Teams of psychologists helping teams: The evolution of the science of team training.

Team training contributes to improved performance, reduced errors, and even saving lives-and it exists today because psychologists collaborated across domains to contribute their expertise. Our objective was to highlight the salient role of multidisciplinary collaboration in the success of team training, an area driven by psychologists responding to real-world problems. In this article, we deliver (a) a historical account of team training research, acknowledging critical turning points that shaped the science; (b) a synthesis of major contributions from subdisciplines of psychology; and (c) a collection of lessons learned in the science and practice of team training. We begin with the history of problems that created a need for solutions and the psychologists across domains who worked together to develop a science to improve teamwork. We give poignant examples of fatal mistakes that incited action and enabled scientific breakthroughs through research partnerships. Next, we detail the theoretical drivers behind the science and the hands-on approach of investigating how we turn a team of experts into an expert team. We discuss the spectrum of team training research throughout time, including major influences that shifted dominant paradigms of thought, while emphasizing its multidisciplinary nature and the contributions of psychologists. Finally, we provide a list of lessons learned from a half-century of multidisciplinary research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The science of teamwork: Progress, reflections, and the road ahead.

We need teams in nearly every aspect of our lives (e.g., hospitals, schools, flight decks, nuclear power plants, oil rigs, the military, and corporate offices). Nearly a century of psychological science has uncovered extensive knowledge about team-related processes and outcomes. In this article, we draw from the reviews and articles of this special issue to identify 10 key reflections that have arisen in the team literature, briefly summarized here. Team researchers have developed many theories surrounding the multilayered aspects of teams, such that now we have a solid theoretical basis for teams. We have recognized that the collective is often stronger than the individual, initiating the shift from individual tasks to team tasks. All teams are not created equal, so it is important to consider the context to understand relevant team dynamics and outcomes, but sometimes teams performing in different contexts are more similar than not. It is critical to have teamwork-supportive organizational conditions and environments where psychological safety can flourish and be a mechanism to resolve conflicts, ensure safety, mitigate errors, learn, and improve performance. There are also helpful teamwork competencies that can increase effectiveness across teams or tasks that have been identified (e.g., coordination, communication, and adaptability). Even if a team is made up of experts, it can still fail if they do not know how to cooperate, coordinate, and communicate well together. To ensure the improvement and maintenance of effective team functioning, the organization must implement team development interventions and evaluate relevant team outcomes with robust diagnostic measurement. We conclude with 3 main directions for scientists to expand upon in the future: (a) address issues with technology to make further improvements in team assessment, (b) learn more about multiteam systems, and (c) bridge the gap between theory and practice. In summary, the science of teams has made substantial progress but still has plenty of room for advancement. (PsycINFO Database Record

Multiple Patient Casualty Scenarios: A Measurement Tool for Teamwork.

INTRODUCTION: Teamwork is a critical aspect of patient care and is especially salient in response to multiple patient casualties. Effective training and measurement improve team performance. However, the literature currently lacks a scientifically developed measure of team performance within multiple causality scenarios, making training and feedback efforts difficult. The present effort addresses this gap by integrating the input of subject matter experts and the science of multicasualty teams and training to (1) identify overarching teamwork processes and corresponding behaviors necessary for team performance and (2) develop a behavioral observation tool to optimize teamwork in multicasualty training efforts. METHOD: A search of articles including team performance frameworks associated with team training was conducted, leading to the identification of a total of 14 articles. Trained coders extracted teamwork processes and the corresponding team behaviors indicative of effective performance from these articles. Five subject matter experts were interviewed using the critical incident technique to identify additional behaviors. RESULTS: Team situation awareness, team leadership, coordination, and information exchange emerged as the four core team processes required for team performance in scenarios with multiple patient casualties. Relevant behaviors and subbehaviors within these overarching processes were identified to inform a pilot behavioral framework of team performance. CONCLUSIONS: The processes and associated behaviors identified within this effort serve as scientifically grounded behaviors of team performance in the case of multiple patient casualties simulated training scenarios. Future work can use and further refine these results to ensure that measures of team performance are grounded in specific, observable, and scientifically delineated behaviors.

Magnetic resonance imaging of Alzheimer's pathology in the brains of living transgenic mice: a new tool in Alzheimer's disease research.

Alzheimer's disease (AD) is the most common cause of dementia in the elderly. Cardinal pathologic features of AD are amyloid plaques and neurofibrillary tangles, and most in the field believe that the initiating events ultimately leading to clinical AD center on disordered metabolism of amyloid beta protein. Mouse models of AD have been created by inserting one or more human mutations associated with disordered amyloid metabolism and that cause early onset familial AD into the mouse genome. Human-like amyloid plaque formation increases dramatically with age in these transgenic mice. Amyloid reduction in humans is a major therapeutic objective, and AD transgenic mice allow controlled study of this biology. Recent work has shown that amyloid plaques as small as 35 microm can be detected using in vivo magnetic resonance microimaging (MRMI) at high magnetic field (9.4 T). In addition, age-dependent changes in metabolite concentration analogous to those that have been identified in human AD patients can be detected in these transgenic mice using single-voxel (1)H magnetic resonance spectroscopy ((1)H MRS) at high magnetic field. These MR-based techniques provide a new set of tools to the scientific community engaged in studying the biology of AD in transgenic models of the disease. For example, an obvious application is evaluating therapeutic modification of disease progression. Toward the end of this review, the authors include results from a pilot study demonstrating feasibility of using MRMI to detect therapeutic modification of plaque progression in AD transgenic mice.

Leadership training design, delivery, and implementation: A meta-analysis.

Recent estimates suggest that although a majority of funds in organizational training budgets tend to be allocated to leadership training (Ho, 2016; O'Leonard, 2014), only a small minority of organizations believe their leadership training programs are highly effective (Schwartz, Bersin, & Pelster, 2014), calling into question the effectiveness of current leadership development initiatives. To help address this issue, this meta-analysis estimates the extent to which leadership training is effective and identifies the conditions under which these programs are most effective. In doing so, we estimate the effectiveness of leadership training across four criteria (reactions, learning, transfer, and results; Kirkpatrick, 1959) using only employee data and we examine 15 moderators of training design and delivery to determine which elements are associated with the most effective leadership training interventions. Data from 335 independent samples suggest that leadership training is substantially more effective than previously thought, leading to improvements in reactions (δ = .63), learning (δ = .73), transfer (δ = .82), and results (δ = .72), the strength of these effects differs based on various design, delivery, and implementation characteristics. Moderator analyses support the use of needs analysis, feedback, multiple delivery methods (especially practice), spaced training sessions, a location that is on-site, and face-to-face delivery that is not self-administered. Results also suggest that the content of training, attendance policy, and duration influence the effectiveness of the training program. Practical implications for training development and theoretical implications for leadership and training literatures are discussed. (PsycINFO Database Record

In vivo magnetic resonance microimaging of individual amyloid plaques in Alzheimer's transgenic mice.

The ability to detect individual Alzheimer's amyloid plaques in vivo by magnetic resonance microimaging (MRI) should improve diagnosis and also accelerate discovery of effective therapeutic agents for Alzheimer's disease (AD). Here, we perform in vivo and ex vivo MRI on double transgenic AD mice as well as wild-type mice at varying ages and correlate these with thioflavin-S and iron staining histology. Quantitative counts of individual plaques on MRI increase with age and correlate with histologically determined plaque burden. Plaques 20 microm in diameter can be detected in AD mice as young as 3 months of age with ex vivo MRI. Plaques 35 microm in diameter can be detected by 9 months of age with in vivo MRI. In vivo MRI of individual Alzheimer's amyloid plaques provides a noninvasive estimate of plaque burden in transgenic AD mice that might be useful in assessing the efficacy of amyloid reduction therapies.

Three-dimensional imaging of fractures in outlet struts of Björk-Shiley convexo-concave heart valves by microcomputed tomography in vitro.

BACKGROUND AND AIMS OF THE STUDY: For implanted Björk-Shiley convexo-concave (BSCC) heart valves, structural failure of the valve's U-shaped outlet strut results in embolization of its blood flow-regulating disc (occluder), with consequent patient morbidity and mortality. After a variable and unpredictable number of cardiac cycles, one strut leg may fatigue ('single-leg separation'; SLS); subsequently the other strut leg may also fatigue, resulting in full structural failure ('outlet strut failure'; OSF). Some BSCC valves are believed to be at more risk of SLS and OSF than others. As valves may function in the SLS condition for some time before OSF occurs, several investigators have sought non-invasive methods to differentiate valves with SLS struts from valves with intact struts in order to provide a rationale for prophylaxis. Herein, we report the use of X-ray microcomputed tomography (micro-CT) to image and characterize SLS strut fractures, including fracture faces otherwise visible only by means of physical sectioning. METHODS: An X-ray micro-CT system was adapted to provide high-resolution, three-dimensional (3D) images of intact and fractured BSCC valve outlet struts in vitro. System modifications included use of a tungsten anode X-ray source to achieve sufficiently high X-ray energies to overcome attenuation within the metal structures, and a hafnium filter to minimize the imaging artifact caused by X-ray beam hardening. For rotating the valve for tomographic scanning, special alignment procedures were developed to maintain the region of interest within the field of view. Typical 3D images of the outlet struts were composed of cubic voxels, 10 microm on a side. Image analysis and display software was used to view the outlet struts and the fractures from several perspectives, including en-face images of fracture surfaces. RESULTS: 3D volume data representations of the SLS and intact outlet struts were obtained, facilitating identification of fracture location and geometry. Enface images of the fracture surfaces were also generated. Several different fracture geometries were observed, such as fractures with and without longitudinal gaps between the fracture faces, and fractures with and without lateral displacement between the faces. En-face views showed varying degrees of roughness on fracture faces. CONCLUSION: This application of micro-CT to image outlet strut fractures in BSCC valve explants demonstrates the value of this method for fracture characterization in vitro, including visualization of fracture faces of SLS struts without physical sectioning. Although the method is not suitable for clinical use because it requires high-intensity X-rays, micro-CT can serve as a tool to understand further any failure mechanisms, and to aid the development of clinical differentiation methods.

Cryostatic micro-computed tomography imaging of arterial wall perfusion.

A double-walled copper vessel, 32 cc in volume, was fabricated for scanning tissue specimens while maintained below freezing point. To keep specimen temperature within +/- 1 degrees C, temperature sensors within the chamber control, the rate of inflow of the cold nitrogen gas vented through the chamber. The specimen is attached to a small platform on top of a vertical pin which is attached to the computer-controlled rotating stage under the vessel. The purpose of this arrangement is to permit scanning of specimens up to 2 cm3 that (1) cannot be "fixed" (e.g., with formalin) because of analyses which are incompatible with prior fixation (certain immunohistochemistry and biomolecular methods), or (2) are "snap"-frozen during a transient process, such as the accumulation and/or washout of radiopaque indicators. Examples of "cryoscans" of porcine carotid and coronary artery wall opacification in either untouched or acutely stented arteries, snap-frozen immediately after selective intra-arterial injection of a contrast agent, show accumulation of contrast in the extravascular space indicating increased endothelial permeability or endothelial and medial disruption following stent placement. The detection of contrast in the adventitia suggest that vasa vasorum deliver the contrast agent from the main lumen to the adventitial extravascular space but not to the media.

Antemortem amyloid imaging and ß-amyloid pathology in a case with dementia with Lewy bodies.

The association between ante mortem [(11)C]-Pittsburgh Compound B (PiB) retention and ß-amyloid (Aß) load, Lewy body (LB) and neurofibrillary tangle (NFT) densities were investigated in a pathologically confirmed case of dementia with Lewy bodies (DLB). A 76 year old man presenting with a clinical diagnosis of DLB had undergone PiB-positron emission tomography (PET), (18)F FDG-PET and magnetic resonance imaging (MRI) 18 months before death. The pathologic diagnosis was DLB neocortical-type with low-likelihood of Alzheimer's disease by NIA-Reagan criteria. Sections from regions of interest (ROI) on post-mortem examination were studied. A significant correlation was found between cortical Aß density and PiB retention in the 17 corresponding ROIs (r = 0.899; p < 0.0001). Bielschowsky silver stain revealed mostly sparse neocortical neuritic plaques, whereas diffuse plaques were frequent. There was no correlation between LB density and PiB retention (r = 0.13; p = 0.66); nor between NFT density and PiB retention (r = -0.36; p = 0.17). The ROI-based analysis of imaging and histopathological data confirms that PiB uptake on PET is a specific marker for Aß density, but cannot differentiate neuritic from diffuse amyloid plaques in this case with DLB.

Does HIV VCT reduce risk behaviors? An observational study in Guatemala City.

OBJECTIVE: We examined the impact of HIV voluntary counseling and testing on self-reported behavioral risks three months after HIV testing. DESIGN: Cohort study comparing self-reported risk behaviors prior to and three months after HIV testing. SETTING: Clinica Familiar Luis Angel Garcia, an HIV specialty clinic located in a Guatemalan National Hospital. SUBJECTS, PARTICIPANTS: 144 people undergoing HIV testing were enrolled. 44 were HIV positive. 41 HIV positive and 49 HIV negative subjects returned for follow-up interviews. INTERVENTION: All subjects were tested and received voluntary counseling regarding HIV infection, transmission, prevention, and interpretation of HIV test results. MAIN OUTCOME MEASURE: The primary study outcome measure was change in self-reported risk behaviors three months after voluntary counseling and testing. RESULTS: Men were more likely than women to report a history of sexually transmitted diseases, more than 2 sexual partners, using alcohol with sex, and receiving money for sex; they were less likely to have a regular partner. 26% of men reported non-heterosexual orientation; no woman did. Alcohol was the primary drug of abuse in both men and women. At three month follow-up HIV positive subjects showed decreases in the average number of sexual partners, use of alcohol with sex, and episodes of unprotected sex. CONCLUSIONS: Voluntary counseling and testing resulted in changes in some self-reported risk behaviors, but only among HIV positive subjects. On nearly all measures men report riskier behavior than women. Alcohol is the most commonly used drug in this population and is often used with sex.

Longitudinal 1H MRS changes in mild cognitive impairment and Alzheimer's disease.

Magnetic resonance (MR)-based volume measurements of atrophy are potential markers of disease progression in patients with amnestic mild cognitive impairment (MCI) and Alzheimer's disease (AD). Longitudinal changes in (1)H MR spectroscopy ((1)H MRS) metabolite markers have not been characterized in MCI subjects. Our objective was to determine the longitudinal (1)H MRS metabolite changes in patients with MCI, and AD, and to compare (1)H MRS metabolite ratios and ventricular volumes in tracking clinical disease progression in AD. The neuronal integrity marker N-acetylaspartate/creatine ratio declined in MCI and AD patients compared to cognitively normal elderly. The change in (1)H MRS metabolite ratios correlated with clinical progression about as strongly as the rate of ventricular expansion, suggesting that (1)H MRS metabolite ratios may be useful markers for the progression of AD. Choline/creatine ratio declined in stable MCI, compared to converter MCI patients and cognitively normal elderly, which may be related to a compensatory mechanism in MCI patients who did not to progress to AD.