Selection tools and student diversity in health professions education: a multi-site study.

Student diversity in health professions education (HPE) can be affected by selection procedures. Little is known about how different selection tools impact student diversity across programs using different combinations of traditional and broadened selection criteria. The present multi-site study examined the chances in selection of subgroups of applicants to HPE undergraduate programs with distinctive selection procedures, and their performance on corresponding selection tools. Probability of selection of subgroups (based on gender, migration background, prior education, parental education) of applicants (N = 1935) to five selection procedures of corresponding Dutch HPE undergraduate programs was estimated using multilevel logistic regression. Multilevel linear regression was used to analyze performance on four tools: prior-education grade point average (pe-GPA), biomedical knowledge test, curriculum-sampling test, and curriculum vitae (CV). First-generation Western immigrants and applicants with a foreign education background were significantly less likely to be selected than applicants without a migration background and with pre-university education. These effects did not vary across programs. More variability in effects was found between different selection tools. Compared to women, men performed significantly poorer on CVs, while they had higher scores on biomedical knowledge tests. Applicants with a non-Western migration background scored lower on curriculum-sampling tests. First-generation Western immigrants had lower CV-scores. First-generation university applicants had significantly lower pe-GPAs. There was a variety in effects for applicants with different alternative forms of prior education. For curriculum-sampling tests and CVs, effects varied across programs. Our findings highlight the need for continuous evaluation, identifying best practices within existing tools, and applying alternative tools.

[Severe peripheral ischemia of rare origin]. / Ischemie severe peripherique d'origine inhabituelle.

The authors describe a rare case of acute peripheral ischemia in a young patient, following a lower limb orthopaedic surgery. The clinical presentation and diagnosis tests suggested a Horton arteritis with peripheral symptoms, although the temporal artery biopsy was negative. Since the etiology was unclear, the authors considered the influence of local trauma (initial and surgical), of Ergot derivatives and antibiotic treatment, but the clinical outcome after corticotherapy strongly indicated a temporal arteritis.

Effects of methyl-beta-cyclodextrin-mediated cholesterol depletion in porcine sperm compared to somatic cells.

In this study, the use of methyl-beta-cyclodextrin (MBCD) to support capacitation of sperm cells was studied. Sperm were incubated with MBCD or alternatively capacitated in an in vitro fertilization medium. The effects of these incubations on phospholipid scrambling (using merocyanin), cholesterol depletion, GM-1 localization (using cholera-toxin B (CTX)), and membrane deterioration were assessed. For comparison, this was also tested in MBCD-treated MDCK cells. In MDCK cells, upto 71% of cholesterol was depleted, which coincided with a more diffuse CTX staining without any obvious effects on cell viability. In sperm, a similar depletion of 53% cholesterol was found after a 10 mM MBCD treatment. However, no merocyanin response was observed in viable sperm after MBCD treatments (indicating a lack of membrane changes associated with sperm capacitation). In contrast to MDCK, cells >1 mM MBCD caused plasma membrane disintegration and rendered sperm immotile. At higher concentrations also acrosome disruption was noted. CTX staining was absent at < 0.1 mM MBCD incubations but appeared at higher MBCD levels and was found to be specific for deteriorated cells that showed morphological signs of acrosome disruption. No significant plasma membrane deterioration, acrosome disruption, and sperm immotility nor CTX staining and only a modest (< 15%) cholesterol depletion were observed in conventionally capacitated sperm, where 40% of the intact sperm showed merocyanin staining. Taken together, the results indicate that membranes of sperm are more sensitive to MBCD-mediated cholesterol depletion than MDCK cells and that the use of MBCD to support sperm capacitation cannot be recommended due to its spermicidal effects.

Capacitation-dependent concentration of lipid rafts in the apical ridge head area of porcine sperm cells.

Lipid architecture of the plasma membrane plays an important role in the capacitation process of the sperm cell. During this process, an increase in membrane fluidity takes place, which coincides with a redistribution of cholesterol to the apical region of the head plasma membrane and subsequently an efflux of cholesterol. Cholesterol is also a major player in the formation of lipid rafts or microdomains in the membrane. Lipid rafts favour specific protein-protein interactions by concentrating certain proteins in these microdomains while excluding others. In this study, we investigated the organization of lipid rafts during in vitro capacitation of boar sperm cells. We report on the presence of the lipid raft-specific proteins caveolin-1 and flotillin-1 in sperm cells. Capacitation induced a change in membrane distribution of these proteins. Lipid analysis on detergent-resistant membranes (DRMs) of sperm cells indicated that capacitation induces a lipid raft concentration rather than a disintegration of lipid rafts, because the total amount of lipid in the DRM fraction remained unaltered. Using a proteomic approach, we identified several major DRM proteins, including proteins involved in capacitation-dependent processes and zona pellucida binding. Our data indicate that sperm raft reorganization may facilitate capacitation-specific signalling events and binding to the zona pellucida.

Bicarbonate and its role in mammalian sperm function.

This paper deals with the effects of bicarbonate induced signaling pathways on plasma membrane lipid organization and downstream protein signaling, and their role in sperm-egg interactions. It also provides an overview of results that indicate that bicarbonate responses are not related to cell death or apoptosis. The information presented shows that only those sperm cells that have functionally completed maturation in the epididymis are sensitive to bicarbonate whereas immature sperm fail to respond to this physiological challenge. Therefore, it is important to selectively analyze the responsive sperm subpopulations when studying sperm capacitation. Moreover, bicarbonate induced signaling responses differ within the diverse sperm structures (e.g. the tail versus the head). Consequently, dissecting sperm structures and signaling areas from each other deserves more attention in sperm capacitation research. The information discussed was obtained from a variety of mammalian species but the basic bicarbonate-mediated sperm responses are similar in most Eutherian species despite some species to species variations (most notably in kinetics rather than the sequence of events). The objective of the paper is to provide a comparative experimental overview of bicarbonate mediated sperm capacitation in the hope that this information will lead to a better understanding of the complex biochemical nature of the involvement of bicarbonate in mammalian sperm capacitation.

[By-passes of the arteries in the leg and the foot (author's transl)]. / Pontages sur les artères de la jambe et du pied.

The author presents the 50 first cases of his serie of by-passes on legs and feet arteries. The various stages of the angiography, anesthesia and operation technique are discussed. The results are divided into three groups; the by-passes always permeable, the patients deceased from another disease still with a permeable by-pass, and the precocious or late failures. The latter are studied more in detail in order to bring out, the reasons of failures and the factors which could improve the present results. The analysis of the results, compared to those of the published cases, shows a satisfying percentage of good results, seen the symptoms and lesions.