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Biomedical subjects

L Ellis

Publications and source records attributed to L Ellis.

At least 145 records · Page 8Linked to original sources
PubMed1982

Pancreatic beta cell function in the neonatal foal.

Plasma concentrations of insulin and glucose were measured in Pony and Thoroughbred foals at birth and at intervals thereafter for up to 7 days. The plasma concentrations of insulin in foals of both breeds at birth were 11.2 +/- 2.5 microU/ml (N = 6) and 13.5 +/- 1.5 microU/ml (N = 16) respectively. These values were similar to those obtained for foals in utero but were significantly less than those in adult animals. There was little variation in the plasma concentrations of insulin and glucose during the first 2 h of life and both concentrations tended to rise in the next 24-48 h. Although there was a significant positive correlation between the endogenous concentrations of insulin and glucose at all the ages studied, the responsiveness of the beta cells and the concentrations of glucose effective in stimulating insulin release changed with age. Injection of glucose (0.5 g/kg as a 50% solution in 0.9% NaCl) stimulated only a small increase in the insulin concentration in newborn Pony foals but evoked a rapid release of insulin in 5-7-day old animals.

Aging↗
PubMed1981

The black mink (Mustela vison). A natural model of immunologic male infertility.

Breeding for fine black fur has generated a colony of mink wherein 20-30% of the males are infertile. Two clinical groups are distinguishable: one being infertile from the start (primary infertility), and the other infertile after one or more years of fertility (secondary fertility). Although the etiology of primary infertility is unknown, the available data indicate that secondary infertility is associated with an autoimmune disease of the testis. Thus, male mink with secondary infertility have (a) higher prevalence and levels of anti-sperm antibody when compared with animals with primary infertility, and the antibody prevalence varies with fur color; (b) severe monocytic orchitis (47%) and/or aspermatogenesis (75%) with negative cultures for bacterial, fungal, mumps, or Coxsackie B viral organisms; (c) massive and extensive granular deposits of mink IgG and/or C3 (71%), typical of immune complexes, along the basal lamina of seminiferous tubules; (d) testes that when eluted with buffer or low pH yielded IgG that was 10-fold enriched in anti-sperm antibody activity as compared with serum IgG; and (e) no immunopathologic evidence of Aleutian mink disease. Although the sperm antigen-antibody complexes in the testis may be important as a pathogenetic mechanism of the testicular disease, there is no correlation between fluorescent anti-sperm antibody detection in the serum and the infertile state. The infertile black mink is a new model of infertility associated with naturally occurring autoimmune disease of the testis.

Animals↗
PubMed1978

Serum zinc levels and urinary zinc excretion in patients with renal transplants.

An investigation into serum and plasma zinc levels and the urinary excretion of zinc in renal allotransplant patients was undertaken. A remarkable number (53%) of low serum and plasma levels of zinc was obtained as well as a distinct increase (37%) in urinary excretion in the 33 patients investigated. Because of the general tendency in these cases to depletion of body stores of zinc, oral supplementation may prove of value.

Humans↗
PubMed1978

Urinary excretion of lysozyme and N-acetyl-beta-D-glucosaminidase in the diagnosis of renal allograft rejection.

The urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) has been claimed to be of high diagnostic value in indicating acute renal graft rejection. Similar claims have been made for the significance of urinary lysozyme excretion. Serial measurements of urinary lysozyme and NAG have been made in 35 patients after renal transplantation, and during 52 suspected rejection episodes. A close correlation has been found between these two parameters although they did not consistently change in parallel. The use of both assays may give a better indication of impending rejection than either assay alone.

Acetylglucosaminidase↗
PubMedDate not supplied

The effects of prenatal stress, and of prenatal alcohol and nicotine exposure, on human sexual orientation.

BACKGROUND: Studies of rats have shown that mothers who are subjected to stress during pregnancy are more likely than mothers who are not stressed during pregnancy to have male offspring who exhibit female-typical sexual receptivity postures (lordosis) in the presence of other males following the onset of puberty. More recent animal experiments have indicated that prenatal exposure to alcohol affects the sexual preferences of male offspring in ways that are similar to the effects of prenatal stress. Research with human subjects have thus far yielded inconsistent findings regarding the effects of prenatal stress on male sexual orientation, and no research has yet addressed the possible involvement of prenatal exposure to alcohol or other widely used recreational drugs, such as nicotine. PURPOSE: The present study was undertaken to determine if prenatal stress could be one of the causes of variations in sexual orientation in humans, both singularly and in conjunction with prenatal exposure to alcohol and nicotine. METHODS: Over 7500 offspring and their mothers provided information regarding the offspring's sexual orientation and the mother's stressful experiences and use of alcohol and nicotine during pregnancy. RESULTS: Findings indicate that prenatal stress has a modest but significant effect on the sexual orientation of male offspring, particularly when the stress occurred during the first trimester of pregnancy. Regarding prenatal exposure to alcohol, no evidence was found to suggest that it impacted offspring sexual orientation of either males or females. Prenatal nicotine exposure, however, appears to significantly increase the probability of lesbianism among female offspring, especially if the exposure occurred in the first trimester along with prenatal stress in the second trimester. CONCLUSION: The present study is consistent with animal models suggesting that prenatal stress disrupts the typical sex hormonal milieu within which male fetal brains are sexed, thereby feminizing/demasculinizing the male's sexual orientation. However, little support was found for similar effects of prenatal alcohol exposure. In the case of prenatal nicotine, this study is the first to suggest that this drug has masculinizing/defeminizing effects on the sexual orientation of female offspring.

Adult↗
PubMedDate not supplied

Sequence of protein disulphide isomerase and implications of its relationship to thioredoxin.

The formation of disulphide bonds is essential to the structure and function of proteins. These bonds rapidly form either cotranslationally or immediately post-translationally in the lumen of the endoplasmic reticulum. Native disulphide pairing for such proteins has been achieved in vitro; however, the rates of reassembly are slow and the conditions non-physiological. To account for these observations, Anfinsen et al. proposed that a 'disulphide interchange protein' was the in vivo catalyst of disulphide bond rearrangement. Other groups discovered an activity with similar characteristics that catalysed the reductive cleavage of insulin and may be associated with insulin degradation, although this result has been disputed. The enzyme involved, protein disulphide isomerase (PDI; EC 5.3.4.1), may be the in vivo catalyst of disulphide bond formation. Here we describe the sequence of cloned rat liver PDI complementary DNA which predicts a protein with two distinct regions homologous with Escherichia coli thioredoxin, a known cofactor in oxidation-reduction reactions. Each of these regions contains the presumed active site sequence Trp-Cys-Gly-His-Cys-Lys, suggesting that PDI, similar in action to thioredoxin, catalyses disulphide bond interchange via an internal disulphide-sulphydryl interchange. The cDNA predicts a signal peptide consistent with the view that PDI is a luminal endoplasmic reticulum protein. PDI messenger RNA, although ubiquitous, is more highly concentrated in secretory cells.

Amino Acid Sequence↗
PubMedDate not supplied

Crystal structure of the tyrosine kinase domain of the human insulin receptor.

The X-ray crystal structure of the tyrosine kinase domain of the human insulin receptor has been determined by multiwavelength anomalous diffraction phasing and refined to 2.1 A resolution. The structure reveals the determinants of substrate preference for tyrosine rather than serine or threonine and a novel autoinhibition mechanism whereby one of the tyrosines that is autophosphorylated in response to insulin, Tyr 1,162, is bound in the active site.

Amino Acid Sequence↗
PubMedDate not supplied

The biosocial female choice theory of social stratification.

For decades, the study of social stratification has been dominated by environmental theories. Herein a theory is proposed that contains both biological and sociocultural elements. The theory asserts that most human females, like females of many other mammalian species, have evolved mating preferences biased toward males who are competent in provisioning resources. This female bias is hypothesized to have been naturally selected because females with these biases nearly always have had a reproductive edge over females who lack such a bias. One result of this bias is that human females preferentially mate with males who strive to rise in social status. This, in turn, has favored males who attain or at least strive for high social status, and who advertise and even exaggerate whatever status they already have achieved. At the genetic level, the theory postulates that alleles have accumulated on the human genome that promote social status-striving and achievement to varying degrees. To account for why males are more prone toward status-striving than females, the theory contends that one or more genes on the Y-chromosome interact with genes on the remaining human chromosomes to incline males to gravitate toward social hierarchies and to strive for niches that are relatively high in those hierarchies. Both tested and untested hypotheses are derived from the theory and compared to the empirical evidence currently available.

Cultural Evolution↗
PubMedDate not supplied

Determination of benzo[a]pyrene and other polycyclic aromatic hydrocarbons (PAHs) at trace levels in human tissues.

A sensitive and rugged gas chromatographic-mass spectrometric (GC-MS) method was developed for determining 11 polycyclic aromatic hydrocarbons (PAHs) in 4-g specimens of human lung, breast, and liver tissue. The method quantitation limit (MQL) was 0.01-0.02 ng/g for benzo[a]pyrene (BaP) and six other five- and six-ring PAHs. The MQL was higher for four-ring PAHs because of their presence at trace levels in method blanks. The average MQLs for pyrene and chrysene were 0.05 and 0.03 ng/g, respectively. The method was applied to 200 human tissue specimens (89 lung, 68 breast, and 43 liver) obtained from patients during surgery. Quality-control results demonstrated average recoveries of 80% or better from reagent controls spiked at the 0.2-ng level and average recoveries from tissue fortified at the 0.25-ng/g level of 66-95%. The precision of the method was determined from duplicate analyses of specimens (16-38% RSD) and from duplicate GC-MS analysis of tissue extracts (8-17%RSD). Benzo[a]pyrene was detected at measurable levels in 87% of the lung specimens. This method makes possible the measurement of ambient levels of PAHs in small samples of human tissue such as those obtained by biopsy.

Benzo(a)pyrene↗
PubMedDate not supplied

Exercise intensity increased by addition of handheld weights to rebounding exercise.

PURPOSE: Researchers who studied the effects of rebound exercise on fitness have concluded that the intensity of rebound exercise elicited only minimal improvements in fitness. This study determined how the addition of arm pumping with handheld weights (HHW) would increase exercise intensity while rebounding. METHODS: Fifteen male subjects (20 to 43 years) ran in place on a mini-trampoline at a stride frequency of 120 foot strikes per minute, with the sole of the foot 15 cm above the rebounder rim. Oxygen uptake (VO2) and heart rate (HR) were measured while rebounding alone, and also while pumping 0.45 kg, 0.91 kg, and 1.36 kg HHW to heights of 61 and 91 cm. RESULTS: All combinations of weights and pumping levels resulted in significantly (P < .05) higher VO2 and HR than rebounding alone. The estimated mean increase in VO2 was 3.2 mL/kg/min when the weight was increased from 0.91 kg to 1.36 kg at the 91 cm pumping height. The corresponding HR increase was 10.1 bpm. Similarly, when 1.36 kg weights were pumped at 91 cm instead of 61 cm, the mean increase in VO2 and HR was 6.2 mL/kg/min and 11.4 bpm, respectively. CONCLUSIONS: The addition of HHW exercise to rebounding substantially increases exercise intensity. Because rebounding without weights results in a relatively low intensity, the addition of HHW should be considered in the use of rebounding for cardiovascular training.

Adult↗
PubMedDate not supplied

Introducing a professional doctorate in nursing and midwifery.

The convergence of a number of factors has led to the emergence of what has come to be known as the 'professional doctorate'. This new doctoral education diverges from the model of research doctorates that have historically predominated for more than a century. The background to these changes and the impetus for the development of this relatively new approach to doctoral preparation is outlined in this article. The infancy of the professional doctorate means little empirical data exist about their operation or their success. In this light, the development of an evaluative framework is described in relation to the implementation of a new professional doctorate for nurses and midwives that has been introduced at the University of Sheffield.

Curriculum↗
PubMedDate not supplied

Attempting to set up a randomised controlled trial.

AIM: The aim of this article is to provide an account of an attempt to set up a randomised control trial (RCT) to evaluate the effects of programmes of continuing professional education on nursing practice. METHOD: The logistical and methodological challenges of the RCT are described, and an alternative quasi-experimental approach is outlined. RESULTS: It was not possible to obtain a sample of potential students due to the many constraints put on managers, mainly in relation to maintaining staff morale and providing a service while staff are away on courses. CONCLUSION: Few studies into the effects of education on nursing practice adopt a randomised control trial (RCT) methodology. Most continue to be process rather than outcome oriented, focusing on such things as teaching and learning strategies. This might be related to the methodological challenges posed by the RCT when applied in social settings.

Aged↗