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Biomedical subjects

S Evans

Publications and source records attributed to S Evans.

At least 19 recordsLinked to original sources

Validity of the leg-to-leg bioimpedance to estimate changes in body fat during weight loss and regain in overweight women: a comparison with multi-compartment models.

OBJECTIVES: To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) method to measure body fat during active weight loss (WL) and weight regain (WR). DESIGN: Longitudinal, 12-week weight loss intervention (3.3-3.8 MJ/day) and subsequent follow-up at 1 year. SUBJECTS: Fifty-eight adult women aged between 24 and 65 years (mean age: 46.8+/-8.9 years) and with a body mass index (BMI) > or =25 kg/m(2) (mean BMI: 31.6+/-2.5 kg/m(2), range=26.0-48.2 kg/m(2)) participated in the study. MEASUREMENTS: Fat mass (FM) was measured at baseline, 12 weeks, 24 weeks and 52 weeks using three- and four-compartment (4-C) models, air displacement plethysmography (ADP), deuterium dilution - total body water (TBW), dual-energy X-ray absorptiometry (DXA), skinfold thickness (SFT), tetrapolar bioelectrical impedance analysis (T-BIA) and LTL. RESULTS: At the end of the weight loss programme, subjects lost 9.9+/-3.5 kg weight (P<0.001) and 7.6+/-0.5 kg fat (P<0.001) but after 1 year they had regained 4.9+/-3.7 kg of weight and 3.7+/-2.9 kg of fat. The 4-C model showed that FM and TBW accounted for 76.2 and 23.6% of the loss in body mass and 81.8 and 17.7% of the tissue accrued during weight regain, respectively. The estimate of body fat change by LTL relative to multi-compartment models (WL(bias+/-2s.d.)=0.51+/-3.26 kg; WR(bias+/-2s.d.)=-0.25+/-2.30 kg) was similar to ADP, DXA and TBW in both phases but it was better than T-BIA (WL(bias+/-2s.d.)=0.17+/-7.90 kg; WR(bias+/-2s.d.)=-0.29+/-7.59 kg) and skinfold thickness (WL(bias+/-2s.d.)=2.68+/-6.68 kg; WR(bias+/-2s.d.)=-0.84+/-3.80 kg). CONCLUSIONS: Weight loss and regain were associated with minimal changes in lean tissue as measured using multi-compartment models. The LTL system is a useful method to measure body composition changes during clinical weight management programmes.

Adipose Tissue↗

Prenatal-through-postnatal exposure to moderate levels of ethanol leads to damage on the hippocampal CA1 field of juvenile rats: a stereology and Golgi study.

Experimental paradigms conducted to assess the neurotoxic effects of ethanol exposure on hippocampus development have yielded controversial findings. Hippocampal CA1 population and some cytoarchitectural parameters of pyramidal cells were studied after exposure to ethanol during early development, in rats. Examination of 30-day-old offspring of rats exposed to moderate levels of ethanol during gestation through lactation showed an increased volume of the hippocampal CA1 field compared to untreated or pair-fed control pups, as well as a reduced number of pyramidal neurons. In addition, the number of spines from surviving CA1 pyramidal neurons was reduced. Furthermore, stubby and wide spines were proportionally increased, while the proportion of mushroom and ramified spines was reduced; no variation in the proportion of thin spines was observed. Because alcoholic women usually drink alcohol before, during, and after pregnancy, a broad-range experimental model of alcohol exposure was used in this study. The present findings show that experimental exposure to moderate levels of ethanol, resembling the human situation in alcoholic mothers, leads to loss of hippocampal CA1 pyramidal neurons, along with several pathological and plastic events in the dendritic arborization of these neurons. Some ethanol-induced excitotoxicity-related mechanisms, which may be underlying these effects, are discussed.

Animals↗

Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts.

The taxonomy of optical emission detected during the critical first few minutes after the onset of a gamma-ray burst (GRB) defines two broad classes: prompt optical emission correlated with prompt gamma-ray emission, and early optical afterglow emission uncorrelated with the gamma-ray emission. The standard theoretical interpretation attributes prompt emission to internal shocks in the ultra-relativistic outflow generated by the internal engine; early afterglow emission is attributed to shocks generated by interaction with the surrounding medium. Here we report on observations of a bright GRB that, for the first time, clearly show the temporal relationship and relative strength of the two optical components. The observations indicate that early afterglow emission can be understood as reverberation of the energy input measured by prompt emission. Measurements of the early afterglow reverberations therefore probe the structure of the environment around the burst, whereas the subsequent response to late-time impulsive energy releases reveals how earlier flaring episodes have altered the jet and environment parameters. Many GRBs are generated by the death of massive stars that were born and died before the Universe was ten per cent of its current age, so GRB afterglow reverberations provide clues about the environments around some of the first stars.

Journal Article↗

'Ready to drink' protein substitute is easier is for people with phenylketonuria.

UNLABELLED: In phenylketonuria (PKU), compliance with taking protein substitute is an issue in teenage and older patients. A 'ready to drink' protein substitute may overcome many of the practical issues associated with its administration. OBJECTIVE: To investigate the efficacy of a liquid protein substitute in a 6-week, three-part, randomized, crossover, controlled study. METHODS: 27 subjects (15 female; 12 male) with PKU with a median age of 30 years (range 8-49 years) were recruited. One subject withdrew from the study. Their median daily dose of protein equivalent was 60 g (range 45-75 g). In parts 1 and 2, subjects were randomized to either a liquid or a powder protein substitute with the same nutritional composition per unit (each 130 ml liquid pouch or 25 g powder sachet contained 15 g protein equivalent). In part 3, subjects chose liquid, powder or a combination of both. Weekly blood phenylalanine (Phe) concentrations were estimated, and during weeks 2, 4 and 6 subjects completed a daily questionnaire on administration issues. RESULTS: All but one of 26 subjects chose the liquid in part 3 as either their sole (69%, n = 18) or partial source (28%, n = 7) of protein substitute. Blood Phe concentrations were significantly better on the liquid (p = 0.03). With the liquid protein substitute, subjects were less self-consciousness (p = 0.003) and found it easier to take away from home (p = 0.001). Overall, the liquid was easier (p < 0.0001), more convenient (p = 0.002) and resulted in less wastage of protein substitute (p = 0.001). CONCLUSION: Liquid protein substitute was popular and efficacious, reduced self-consciousness and overall improved compliance of teenagers and adults with PKU.

Adolescent↗

Mitochondrial-related gene expression changes are sensitive to agonal-pH state: implications for brain disorders.

Mitochondrial defects in gene expression have been implicated in the pathophysiology of bipolar disorder and schizophrenia. We have now contrasted control brains with low pH versus high pH and showed that 28% of genes in mitochondrial-related pathways meet criteria for differential expression. A majority of genes in the mitochondrial, chaperone and proteasome pathways of nuclear DNA-encoded gene expression were decreased with decreased brain pH, whereas a majority of genes in the apoptotic and reactive oxygen stress pathways showed an increased gene expression with a decreased brain pH. There was a significant increase in mitochondrial DNA copy number and mitochondrial DNA gene expression with increased agonal duration. To minimize effects of agonal-pH state on mood disorder comparisons, two classic approaches were used, removing all subjects with low pH and agonal factors from analysis, or grouping low and high pH as a separate variable. Three groups of potential candidate genes emerged that may be mood disorder related: (a) genes that showed no sensitivity to pH but were differentially expressed in bipolar disorder or major depressive disorder; (b) genes that were altered by agonal-pH in one direction but altered in mood disorder in the opposite direction to agonal-pH and (c) genes with agonal-pH sensitivity that displayed the same direction of changes in mood disorder. Genes from these categories such as NR4A1 and HSPA2 were confirmed with Q-PCR. The interpretation of postmortem brain studies involving broad mitochondrial gene expression and related pathway alterations must be monitored against the strong effect of agonal-pH state. Genes with the least sensitivity to agonal-pH could present a starting point for candidate gene search in neuropsychiatric disorders.

Antidepressive Agents↗

Critical interactions between TGF-beta signaling/ELF, and E-cadherin/beta-catenin mediated tumor suppression.

Inactivation of the transforming growth factor-beta (TGF-beta) pathway occurs often in malignancies of the gastrointestinal (GI) system. However, only a fraction of sporadic GI tumors exhibit inactivating mutations in early stages of cancer formation, suggesting that other mechanisms play a critical role in the inactivation of this pathway. Here, we show a wide range of GI tumors, including those of the stomach, liver and colon in elf+/- and elf+/- / Smad4+/- mutant mice. We found that embryonic liver fodrin (ELF), a beta-Spectrin originally identified in endodermal stem/progenitor cells committed to foregut lineage, possesses potent antioncogenic activity and is frequently inactivated in GI cancers. Specifically, E-cadherin accumulation at cell-cell contacts and E-cadherin-beta-catenin-dependent epithelial cell-cell adhesion is disrupted in elf+/- / Smad4+/- mutant gastric epithelial cells, and could be rescued by ectopic expression of full-length elf, but not Smad3 or Smad4. Subcellular fractionation revealed that E-cadherin is expressed mainly at the cell membrane after TGF-beta stimulation. In contrast, elf+/- / Smad4+/- mutant tissues showed abnormal distribution of E-cadherin that could be rescued by overexpression of ELF but not Smad3 or Smad4. Our results identify a group of common lethal malignancies in which inactivation of TGF-beta signaling, which is essential for tumor suppression, is disrupted by inactivation of the ELF adaptor protein.

Animals↗

A stastistical system for detecting Salmonella outbreaks in British livestock.

Worldwide, early detection systems have been used in public health to aid the timely detection of increases in disease reporting that may be indicative of an outbreak. To date, their application to animal surveillance has been limited and statistical methods to analyse human health data have not been viewed as being applicable for animal health surveillance data. This issue was investigated by developing an early detection system for Salmonella disease in British livestock. We conclude that an early detection system, as for public health surveillance, can be an effective tool for enhanced surveillance. In order to implement this system in the future and extend it for other data types, we provide recommendations for improving the current data collection process. These recommendations will ensure that quality surveillance data are collected and used effectively to monitor disease in livestock populations.

Animals↗

Social patterns of food sharing in monogamous owl monkeys.

Captive owl monkeys (Aotus nancymaae, A. azarai) share food frequently within both families and pairs. In this study food sharing was observed in seven mated pairs and four families (i.e., four mated pairs and their offspring). Patterns of food sharing were examined with respect to age class, sex, and the presence or absence of dependent offspring. Within families, most food transfers were from adult males to developing offspring. Adult males and females transferred food to their mates in caged pairs as well as in family units. Food interactions between adults are as likely to result in food transfers as those between adults and offspring. This pattern of food sharing between mates in a monogamous species may serve both nutritional and social functions that differ from those in polygamous species.

Animals↗

Fair Access to Care Services (FACS): implementation in the mental health context of the UK.

Since April 2003, all adults requiring social care services must have an assessment to determine their eligibility, which is set within the four-level framework of Fair Access to Care Services [FACS; LAC (2002)13]. This paper examines the implementation of FACS by community mental health teams in eight sites in mental health partnership trusts, and one in a mental health and social care trust in the UK. Twenty-eight respondents (managers within trusts and social services departments) participated in in-depth qualitative interviews, which were undertaken between August 2004 and February 2005. The interviews covered: consultation with users and partner organisations; training and briefings for staff; FACS thresholds; integration of FACS and the Care Programme Approach; and the impact of implementing FACS on budgetary arrangements between health and social care. Using the framework analysis approach to analyse data, it was found that FACS implementation in mental health services has been somewhat haphazard, and has identified real differences between health and social care approaches to eligibility determination, assessment and priorities. In particular, the type and amount of consultation, training and induction into FACS was variable, and in some cases, unacceptably poor. While FACS may have reduced variability between authorities, the exercise of professional judgement in the operation of FACS and the lack of high-quality preventative services remain as potential sources of inequity within the system. The authors conclude that FACS has revealed and reinforced a growing separation rather than an integration of mental health and social care ideas and practices, at least in the participating sites.

Adult↗

Home enteral feeding audit 1 year post-initiation.

UNLABELLED: OBJECTIVE To determine the practical problems that families of children on home enteral tube feeds (HETF) experience in the first year post-hospital discharge. METHODS Thirty parents/carers of children (0-16 years) completed a multiple choice/short answer questionnaire by interview 12 months after discharge from hospital. Issues addressed included: home delivery of feed and equipment; pump usage; tube changes; and overnight feeding. RESULTS: The main problems identified were: sleep disturbance (75%); frequent tube dislodgement (46%); tube blockages (41%); inability of some home delivery companies (HDC) to provide all the paediatric special feeds required (43%); and pump inaccuracy (23%). Conclusions Children on long-term HETF and their families experience significant problems with sleep disturbance, tube dislodgement and tube blockage. In addition, accuracy of pumps and obtaining feed and equipment was a source of stress. Dietitians and community nurses urgently need to explore solutions to the common problems associated with overnight feeding. Furthermore, regular home reviews are necessary in long-term HETF to continue to identify and minimize problems.

Adolescent↗

Home delivery of dietary products in inherited metabolic disorders reduces prescription and dispensing errors.

UNLABELLED: In the UK, for patients with inherited metabolic disorders (IMD) the traditional system for acquiring essential dietary products [patient prompted prescriptions generated by a medical general practitioner (GP) and dispensed by a chemist] is problematic. OBJECTIVE: To investigate the efficacy of a home delivery service (HDS) for essential dietary products (EDP) (i.e. protein substitutes, milk replacements, energy and vitamin and mineral supplements) for subjects with IMD, particularly examining any prescription and dispensing errors, metabolic control and consumer satisfaction. METHODS: A prospective, controlled, home delivery trial for EDP was conducted in patients with IMD for 12 months. Sixty-two patients with IMD [50 with phenylketonuria (PKU); 12 with other IMD: aged 6 months-30 years] were recruited. Thirty subjects used a monthly HDS (Homeward: Nutricia) to receive EDP, 32 remained on the traditional system. Each month, the HDS checked home stock levels of EDP, obtained their prescriptions directly from GP's, and then delivered them to the subjects' homes. An independent researcher completed monthly telephone interviews with patients/parents about any EDP prescription errors or delay in receipt. RESULTS: Incorrect protein substitute was dispensed once by the HDS compared with nine subjects who had 12 errors in the control group (P = 0.01); incorrect flavours of protein substitute were dispensed to the home delivery group once compared with eight subjects getting 11 errors via the chemist (P = 0.03). The HDS delayed delivery of protein substitute for one subject on three occasions compared with 39 occasions in 16 subjects via the chemist (P = 0.001). In patients with PKU, plasma phenylalanine control deteriorated in the control group (P < 0.05) but not in the HDS group. CONCLUSIONS: The long-term use of a HDS for EDP in IMD is safer, effective and more reliable than conventional systems.

Adolescent↗

A link between prompt optical and prompt gamma-ray emission in gamma-ray bursts.

The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

Journal Article↗

Anti-sulfatide antibodies in HIV-infected individuals with sensory neuropathy.

We used ELISA to estimate the prevalence of anti-sulfatide antibodies in HIV-infected individuals with distal sensory neuropathy (DSP) and compared the results with the prevalence in HIV-infected individuals without DSP and in individuals with neuropathy who are not infected with HIV. We found that 36% of HIV+/DSP+ individuals had immunoglobulin (Ig) G anti-sulfatide antibody titers greater than 1,500, whereas IgG anti-sulfatide antibodies were rarely found in HIV+/DSP- or HIV-/DSP+ patients.

Autoantibodies↗

"Sneaky disease": the body and health knowledge for people at risk for coronary heart disease in Ontario, Canada.

The contribution of modifiable risk factors to the prevalence of coronary heart disease (CHD) has been well documented in the literature. A focus group component of a cardiovascular risk reduction project, The Community Outreach in Heart Health and Risk Reduction Trial was designed to explore issues that facilitate or constrain individual efforts to implement changes to health behaviours. Eight focus groups were conducted in urban, northern and rural sites in Ontario, Canada. In this article, we elaborate on the difficulties all group members experienced as they attempted to interpret their personal candidacy for CHD. For many participants, CHD was an undetectable or "sneaky disease" in its earlier stages, thus coronary risk was to them an abstract concept that could not ordinarily be detected through sensory perception. Participants drew on three possible strategies to determine their candidacy for CHD: they cognitively engaged in weighing risks, they relied on the interpretive powers of medical hermeneutics, or they waited for "the big event". The findings suggest that lay understandings of the body and health differ from those of health professionals and educators, and that lay understandings differ according to SES and gender. This has implications for health literacy and must be considered in devising strategies for health education.

Adult↗

Changes in weight and lean body mass during highly active antiretroviral therapy.

BACKGROUND: Few studies have prospectively evaluated the impact of highly active antiretroviral therapy (HAART) on body weight and lean body mass (LBM) or explored the impact of baseline immunologic or virological changes on these parameters. METHODS: Adult AIDS Clinical Trials Group (ACTG) protocol 892 was a prospective, 48-week, multisite observational study of body composition conducted during 1997-2000 among 224 antiretroviral-naive and antiretroviral-experienced subjects coenrolled into various adult ACTG antiretroviral studies. Assessments included human immunodeficiency virus type 1 (HIV-1) RNA load (by polymerase chain reaction); T lymphocyte subset analysis; Karnofsky score; height (baseline only); weight, LBM, and fat (by bioelectrical impedance analysis); and functional performance (by questionnaire). RESULTS: Overall, only modest median increases in body weight (1.9 kg) and LBM (0.6 kg) occurred after 16 weeks of therapy. Significantly greater median increases in body weight (2.1 vs. 0.5 kg; P=.045) occurred in subjects who achieved virological suppression (HIV-1 RNA load, <500 copies/mL) at week 16 than in subjects who did not. Subjects who were antiretroviral naive at baseline gained more weight (median increase in body weight, 2.6 vs. 0.0 kg; P<.001) and LBM (1.0 vs. 0.1 kg; P=.002) after 16 weeks of treatment than did subjects who were antiretroviral experienced. Subjects with lower baseline CD4 cell counts (<200 cells/mm3) and subjects with higher baseline HIV-1 RNA loads (> or =100,000 copies/mL) were more likely to show increases in LBM of >1.5 kg (P=.013 and P=.005, respectively). CONCLUSIONS: HAART had modestly favorable effects on body composition, particularly in patients with greater pretreatment immunocompromise and virological compromise. The difference between antiretroviral-naive and antiretroviral-experienced subjects with regard to the ability to achieve increased body weight and LBM requires more study.

Adiposity↗

Bounding the risk of crew loss following orbital debris penetration of the International Space Station at assembly stages 1J and 1E.

Orbital debris impacts on the International Space Station occur frequently. To date, none of the impacting particles has been large enough to penetrate manned pressurized volumes. We used the Manned Spacecraft Crew Survivability code to evaluate the risk to crew of penetrations of pressurized modules at two assembly stages: after Flight 1J, when the pressurized elements of Kibo, the Japanese Experiment Module, are present, and after Flight 1E, when the European Columbus Module is present. Our code is a Monte-Carlo simulation of impacts on the Station that considers several potential event types that could lead to crew loss. Among the statistics tabulated by the program is the probability of death of one or more crew members in the event of a penetration, expressed as the risk factor, R. This risk factor is dependent on details of crew operations during both ordinary circumstances and decompression emergencies, as well as on details of internal module configurations. We conducted trade studies considering these procedure and configuration details to determine the bounds on R at the 1J and 1E stages in the assembly sequence. Here we compare the R-factor bounds, and procedures could that reduce R at these stages.

Accident Prevention↗

The search for the neurobiological basis of vulnerability to drug abuse: using microarrays to investigate the role of stress and individual differences.

Basic neurobiological studies have led to great progress in our understanding of the mechanisms of action of drugs of abuse. Much has been learned about the brain response from the moment a psychoactive drug enters the organism onwards, including the psychological, neurobiological and peripheral effects of repeated drug administration, withdrawal and re-exposure. However, to relate this knowledge to the human experience requires further research on the antecedents of drug-taking behavior and the factors that predispose particular individuals to drug seeking and drug abuse. Thus, it is important to address several issues at the fundamental level: (1) Why are some individuals more vulnerable to drugs of abuse more than others? Is there a broader dimension or dimensions of emotional reactivity that contribute to this difference in vulnerability? (2) What is the effect of psychosocial stress on drug-seeking and drug-taking behavior, and are the effects distinct across individuals? (3) Since both drug-taking behavior and stress have sustained and pervasive effects on the brain, can we use microarrays to discern the "neural signature" or "neural phenotype" associated with these processes, and can we distinguish this signature across individuals with differing propensities to taking drugs? In the present paper, we summarize some of our early attempts at addressing these questions. We rely on animal studies aimed at characterizing the emotional and stress reactivity of rats with different propensities to self-administer drugs (high responders and low responders); we briefly describe the effect of a psychosocial stressor on these animals; we then detail a study using microarray technology aimed at investigating the "neural phenotype" associated with social defeat stress in the high vs. low responder animals. This "discovery" approach is used as a starting place for identifying novel mechanisms that might alter the vulnerability of different individuals to drug-seeking behavior. The power and limits of this approach, and its future directions, are discussed within this general framework.

Animals↗