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Biomedical subjects

S Chappell

Publications and source records attributed to S Chappell.

14 recordsLinked to original sources
PubMed2006

Angiotensinogen gene variants and small-for-gestational-age infants.

In 2003, the angiotensinogen (AGT) gene was found to be associated with infants small for gestational age (SGA). The present study of 107 pregnancies affected by SGA infants and 101 normal pregnancies was designed to further investigate this association. Maternal or fetal AGT genotype or haplotype frequencies did not differ between SGA and normal pregnancies (P > 0.35). Quantitative trait analysis of mothers with normal pregnancies demonstrated an association between AGT haplotype and blood pressure and body mass index at antenatal booking (P = 0.04), suggesting that AGT may play a role in the complex relationship between body mass and blood pressure in healthy pregnant women.

Adult↗
PubMed2002

Antimicrobial resistance in Salmonella isolated from animals and their environment in England and Wales from 1988 to 1999.

Resistance to 16 antimicrobial agents was monitored in 109,125 Salmonella cultures isolated from animals, their environment and feedstuffs between 1988 and 1999. The sensitivity of the 6512 isolates of Salmonella enterica enterica serotype Dublin to all the antimicrobial agents tested varied from 98.2 per cent in 1997 to 99.7 per cent in 1990 and 1996. In contrast, among 28,053 isolates of Salmonella enterica enterica serotype Typhimurium, there was a marked decrease in their sensitivity to all the antimicrobial agents tested, from 57.4 per cent in 1992 to 7.6 per cent in 1995, owing to the widespread occurrence in farm animals of S Typhimurium isolates of the definitive type DT104, resistant to ampicillin, sulphonamides, streptomycin, chloramphenicol and tetracyclines, although the percentage of sensitive isolates increased to 18.4 per cent in 1999, when the incidence of DT104 had decreased. Some isolates of DT104 also showed an increase in resistance to potentiated sulphonamides (2.4 per cent in 1989 to 19.2 per cent in 1999) and nalidixic acid (0 per cent in 1992, 3.8 per cent in 1995 to a peak of 16.9 per cent in 1998). In 1996, 5.1 per cent of 1086 isolates of S Typhimurium from cattle and 35.9 per cent of 192 isolates of S Typhimurium from poultry showed resistance to nalidixic acid. Of the other 74,528 Salmonella isolates, the percentage of strains sensitive to all the antimicrobials tested decreased slightly from 88.2 per cent in 1988 to 70.6 per cent in 1996 and then increased slightly to 73.7 per cent in 1999. The commonest of these other Salmonella serotypes was Salmonella Enteritidis (20,982), which remained predominantly susceptible (ranging from 81.4 to 97.4 per cent) during the study period. Few isolates were resistant to commonly used veterinary antimicrobials, for example, furazolidone, the use of which was banned in 1990, and the aminoglycoside, apramycin.

Animal Feed↗
PubMed1999

Collegiate coaches' knowledge of eating disorders.

OBJECTIVE: To assess, through exploratory research, 1) collegiate coaches' knowledge of eating disorders, 2) the confidence of collegiate coaches in their response correctness to questions about eating disorders among athletes, and 3) demographic data related to prior education about eating disorders and the role of the athletic department in providing such educational experiences. DESIGN AND SETTING: We distributed a 2-part questionnaire to 258 NCAA Division I-A coaches from 5 universities selected by sampling convenience. SUBJECTS: One hundred thirty-eight collegiate coaches responded to the questionnaire for a response rate of 53.5%. MEASUREMENTS: Our survey consisted of 30 true-false questions that tested knowledge of eating disorders overall and in 5 domains. These domains included etiology, identifying signs and symptoms, management and treatment, risk factors, and education and prevention of eating disorders. Coaches indicated their level of certainty in their responses by rating their confidence level on a 4-item Likert-type scale. Demographic data focused on educational programs attended by coaches and teams. Descriptive statistics were used to analyze all data. RESULTS: Our results suggest a need for coaches to achieve a greater knowledge of eating disorders in all domains. Evidence showed that educational programs about eating disorders were not often sponsored by the athletic department for coaches or athletes. There seemed to be poor communication between athletic departments and coaches regarding the availability of eating disorder educational resources. CONCLUSIONS: Data suggested coaches could benefit from comprehensive education in all domains of eating disorders; however, further study is needed to validate these findings, to determine the actual effectiveness of education in the prevention of eating disorders, and to differentiate coaches' knowledge specific to sport coached and to coach and team sex.

Journal Article↗
PubMed1997

Molecular pathology of breast cancer and its application to clinical management.

Breast cancer is a major cause of morbidity and mortality in women in many parts of the world. Breast carcinomas are heterogenous in their biological and clinical behaviour and a greater understanding of how they develop and progress could lead to more directed forms of screening and therapy. It is important to determine the molecular mechanisms underlying the natural history of breast cancer. Developments in the techniques for molecular analysis have meant that they can now be applied to a large range of clinical material such as cytological preparations and fixed, embedded material, so increasing the potential for relating any molecular alterations to clinical behaviour and response to therapy. In this review we consider recent developments in three areas of importance to breast cancer; genetic analysis-oncogenes, tumour suppressor genes, loss of heterozygosity, microsatellite instability, familial breast cancer; steroid receptors, oestrogen regulated proteins, epidermal growth factor receptor, growth factors particularly transforming growth factor beta; and cell adhesion, invasion and metastasis-E-cadherin, integrins, proteases. These are discussed in relation to potential for screening, prognosis and treatment.

Breast Neoplasms↗
PubMed1997

Substrate oxidation at rest and during exercise: effects of menstrual cycle phase and diet composition.

The estrogen hormones have been shown to be highly glycogenic as well as lipolytic in nature. It is unknown whether the metabolic actions of estrogens impact upon energy metabolism during exercise. The composition of prior diet, however, does affect exercise energy metabolism. This study examined the influence of menstrual cycle phase (mid-follicular [FP; low estrogen] vs. mid-luteal [LP; high estrogen]) and diet composition on the rate of substrate oxidation for carbohydrate (CHO) and lipid at rest and during various intensities of physical exercise. Nine subjects completed an experimental session under four different menstrual cycle-diet conditions: 1) FP following a 3-day high CHO diet [75% total caloric intake], 2) FP following a 3-day low CHO diet [35% total caloric intake], 3) LP following a 3-day high CHO diet, and 4) LP following a 3-day low CHO diet. In each of the experimental sessions substrate oxidation was determined at rest and during cycle ergometer exercise at intensities of 30, 50, and 70% VO2max, respectively. Statistically significant (p < 0.05) interaction effects on substrate oxidation due to the menstrual cycle phase and diet conditions were found at rest and during 30%-50% exercise. In general, CHO oxidation was lowest and lipid oxidation highest in the LP under a low CHO diet condition.

Adolescent↗
PubMed1988

Calcium retention and increased vascular reactivity caused by a hypothalamic sodium transport inhibitor.

1. Using a previously established method of isolating an active-sodium-transport inhibitor (ASTI) from hypothalamic cell culture medium, the inhibitor was isolated and partially purified from sequential passages through Sephadex G-25 and h.p.l.c., and its effects on de-endothelialized rabbit aortic strips were investigated. 2. ASTI caused a cumulative concentration-dependent increase in tension which reversed slowly after wash, and the wash showed an identical effect on fresh strips. 3. Ouabain, used as a control, also caused a concentration-dependent increase in tension which reached a plateau at a concentration of 10 mmol/l. Both ouabain and ASTI caused a significant potentiation of the vasoconstrictor effect of noradrenaline at concentrations of 1 nmol/l-0.1 mmol/l. 4. Both ASTI and ouabain caused a significantly greater (P less than 0.01) calcium retention than control medium in aortic strips. 5. Incubation of ASTI with prolidase, chymotrypsin and carboxypeptidase A destroyed the vasoconstrictor effects as well as its inhibitory effects on sodium, potassium-dependent adenosine triphosphatase and sodium efflux from erythrocytes, but leucine aminopeptidase was ineffective. 6. These studies suggest that hypothalamic cells in culture release a peptidic inhibitor of active sodium transport which increases vascular reactivity, potentiates vasoconstrictor effects of noradrenaline and causes calcium retention.

Animals↗
PubMed1987

Problems and pitfalls in the isolation of an endogenous Na+, K+-ATPase inhibitor.

Plasma from volume-expanded and salt-loaded hypertensive animals and from patients with essential hypertension has been reported to inhibit Na+, K+-adenosine triphosphatase (ATPase). Inhibition of the sodium pump in vascular smooth muscle caused by such a circulating factor could increase vascular tone and sensitivity to vasoactive agents, and thereby result in arterial hypertension. Numerous efforts in the past failed to isolate the putative factor from urine and plasma. Recent studies have suggested that the hypothalamus is an important source of an endogenous Na+, K+-ATPase inhibitor, but its isolation from the tissue extracts has been rendered difficult by the presence of other cellular constituents that cause artifactual interference with the assays and purification procedures. Using an alternative approach of isolating the inhibitor from culture medium, we found that dispersed fetal rat hypothalamic neurons in a capillary culture system release a heat-stable, peptidic, low-molecular-weight, active sodium transport inhibitor that causes a reversible increase in vascular tone, sensitizes vascular smooth muscle to the vasoactive effect of norepinephrine, and possesses several characteristics of the putative endogenous digitalislike factor. This inhibitor may be a chemical mediator linking kidney, brain, and cardiovascular system in the genesis of experimental volume-expanded and salt-loaded hypertension and human essential hypertension.

Animals↗
PubMed1986

Characterization of the mechanical behavior of isolated papillary muscle preparations of the ferret.

The characteristics of isometric and isotonic contraction were studied in isolated papillary muscle preparations from the right ventricle of the ferret and compared with those previously reported for comparable preparations from cat and rat. The effects of stimulation rate, temperature, extracellular calcium concentration, caffeine, verapamil, and ouabain were measured. Afterloaded contractions and load clamps were used to study the mechanics of relaxation. The contractile characteristics of ferret papillary muscle preparation appear to be intermediate in many respects between those reported for cat and rat preparations.

Animals↗
PubMedDate not supplied

Analysis of a spacecraft life support system for a Mars mission.

This report summarizes a trade study conducted as part of the Fall 2002 semester Spacecraft Life Support System Design course (ASEN 5116) in the Aerospace Engineering Sciences Department at the University of Colorado. It presents an analysis of current life support system technologies and a preliminary design of an integrated system for supporting humans during transit to and on the surface of the planet Mars. This effort was based on the NASA Design Reference Mission (DRM) for the human exploration of Mars [NASA Design Reference Mission (DRM) for Mars, Addendum 3.0, from the world wide web: http://exploration.jsc.nasa.gov/marsref/contents.html.]. The integrated design was broken into four subsystems: Water Management, Atmosphere Management, Waste Processing, and Food Supply. The process started with the derivation of top-level requirements from the DRM. Additional system and subsystem level assumptions were added where clarification was needed. Candidate technologies were identified and characterized based on performance factors. Trade studies were then conducted for each subsystem. The resulting technologies were integrated into an overall design solution using mass flow relationships. The system level trade study yielded two different configurations--one for the transit to Mars and another for the surface habitat, which included in situ resource utilization. Equivalent System Mass analyses were used to compare each design against an open-loop (non-regenerable) baseline system.

Air Conditioning↗