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.

[Good medical education is impossible without computers]. / Zonder computers geen goed onderwijs in de geneeskunde.

Computers are medical instruments, for which reason they must be included in the medical curriculum. As educational tools, electronic teaching environments, multimedia applications and computers stimulate self-study. Moreover, computers make the medical literature readily accessible and facilitate the administration of the training programme. They are thus an indispensable part of medical education, and of academic and student administration.

Identification of swelling-activated Cl(-) current in rabbit cardiac Purkinje cells.

The presence and functional role of the swelling-activated Cl(-) current (I(Cl(swell))) in rabbit cardiac Purkinje cells was examined using patch-clamp methodology. Extracellular hypotonicity (210 or 135 mOsm) activated an outwardly rectifying, time-independent current with a reversal potential close to the calculated Cl(-) equilibrium potential (E(Cl)). The magnitude of this current was related to tonicity of the superfusate. The current was blocked by 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). These features are comparable to those of I(Cl(swell)) found in sinoatrial nodal, atrial, and ventricular myocytes. I(Cl(swell)) activation at 210 and 135 mOsm depolarized the resting membrane potential with 6 and 10 mV and shortened the action potential by approximately 18 and approximately 33%, respectively. DIDS partially reversed I(Cl(swell))-induced action potential changes. We conclude that I(Cl(swell)) is present in Purkinje cells and its activation leads to action potential shortening and resting membrane potential depolarization, both of which can promote the development of reentrant arrhythmias.

Ca2+-activated Cl- current reduces transmural electrical heterogeneity within the rabbit left ventricle.

OBJECTIVE: Various cationic membrane channels contribute to the heterogeneity of action potential configuration between the transmural layers of the left ventricle. The role of anionic membrane channels is less intensively studied. We investigated the role of the Ca2+-activated Cl- current, ICl(Ca), in transmural electrical heterogeneity. METHODS AND RESULTS: We determined the density of ICl(Ca) and its physiological role in subepicardial and subendocardial ventricular myocytes of rabbit using the patch-clamp technique. ICl(Ca) was measured as the 4,4'diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) sensitive current. The current-voltage relationships and the densities of ICl(Ca) were similar in subepicardial and subendocardial myocytes. However, the functional role of ICl(Ca) exhibited striking differences. In subendocardial myocytes, blockade of ICl(Ca) by DIDS increased action potential duration (APD) significantly at all measured stimulus frequencies (3.33-0.2 Hz). In subepicardial myocytes, ICl(Ca) blockade increased APD only at 3.33 Hz, but not at the lower stimulus frequencies. At 1 Hz, ICl(Ca) blockade in subepicardial myocytes only caused an APD increase when the transient outward K+ current, Ito1, was blocked. CONCLUSIONS: The densities and gating properties of ICl(Ca) are similar in subepicardial and subendocardial myocytes. ICl(Ca) contributes to APD shortening in subendocardial, but not in subepicardial myocytes except at 3.33 Hz. These differences in functional expression of ICl(Ca) reduce the electrical heterogeneity in rabbit left ventricle.

Role of Ca2+-activated Cl- current during proarrhythmic early afterdepolarizations in sheep and human ventricular myocytes.

OBJECTIVES: The proarrhythmic early afterdepolarizations (EADs) during phase-2 of the cardiac action potential (phase-2 EADs) are associated with secondary Ca2+-release of the sarcoplasmic reticulum. This makes it probable that the Ca2+-activated Cl- current [ICl(Ca)] is present during phase-2 EADs. Activation of ICl(Ca) during phase-2 of the action potential will result in an outwardly directed, repolarizing current and may thus be expected to prevent excessive depolarization of phase-2 EADs. The present study was designed to test this hypothesis. METHODS AND RESULTS: The contribution of ICl(Ca) during phase-2 EADs was studied in enzymatically isolated sheep and human ventricular myocytes using the patch-clamp methodology. EADs were induced by a combination of a low stimulus frequency (0.5 Hz) and exposure to 1 microm noradrenaline. In sheep myocytes, the ICl(Ca) blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 0.5 mm) abolished phase-1 repolarization of the action potential in all myocytes tested. This indicates that ICl(Ca) is present in all sheep myocytes. However, DIDS had no effect on phase-2 EAD characteristics. In human myocytes, DIDS neither affected phase-1 repolarization nor phase-2 EAD characteristics. CONCLUSION: In sheep ventricular myocytes, but not in human ventricular myocytes, ICl(Ca) contributes to phase-1 repolarization of the action potential. In both sheep and human myocytes, ICl(Ca) plays a limited role during phase-2 EADs.

The medical information sciences program of Amsterdam.

The medical information sciences program of Amsterdam has been in existence for 15 years now. Starting in 1987, the program has been modified several times. Now a full-fledged 4 years master program exists. Students are taught skills to adequately and systematically apply information and communication technologies in order to optimize health care information processing. The program is offered within the Faculty of Medicine of the University of Amsterdam. The structure and contents of the current program will be described.

Limited role of Ca2+-activated Cl- current in early afterdepolarisations.

OBJECTIVES: The proarrhythmic, early afterdepolarisations during phase two of the action potential (phase-2 EADs) are associated with secondary Ca2+ release from the sarcoplasmic reticulum. This makes it probable that the Ca2+-activated Cl- current (ICl(Ca)) may contribute to phase-2 EADs. Activation of ICl(Ca) during phase two of the action potential will result in a repolarising current and may thus be expected to prevent excessive depolarisation of phase-2 EADs. The present study was designed to test this hypothesis. METHODS: The contribution of ICl(Ca) during phase-2 EADs was studied in enzymatically isolated sheep ventricular myocytes using the patch-clamp methodology. EADs were induced at a stimulus frequency of 0.5 Hz by exposure of the myocytes to 1 µM noradrenaline. RESULTS: The ICl(Ca) blocker 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS, 0.5 mM) abolished phase-1 repolarisation of the action potential in all myocytes tested. This indicates that ICl(Ca) is present in all myocytes. However, DIDS had no effect on phase-2 EAD characteristics. CONCLUSION: In sheep ventricular myocytes, ICl(Ca) contributes to phase-1 repolarisation of the action potential, but plays a limited role in phase-2 EADs.

Ionic mechanism of delayed afterdepolarizations in ventricular cells isolated from human end-stage failing hearts.

BACKGROUND: Animal studies have shown that the Ca(2+)-activated Cl(-) current (I(Cl(Ca))) and the Na(+)/Ca(2+) exchange current (I(Na/Ca)) contribute to the transient inward current (I(ti)). I(ti) is responsible for the proarrhythmic delayed afterdepolarizations (DADs). We investigated the ionic mechanism of I(ti) and DADs in human cardiac cells. METHODS AND RESULTS: Human ventricular cells were enzymatically isolated from explanted hearts of patients with end-stage heart failure and studied with patch-clamp methodology. I(ti)s were elicited in the presence of 1 micromol/L norepinephrine by trains of repetitive depolarizations from -80 to +50 mV. DADs were induced in the presence of 1 micromol/L norepinephrine at a stimulus frequency of 1 Hz. I(ti) currents were inwardly directed over the voltage range between -110 and + 50 mV. Neither the Cl(-) channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid nor changes in [Cl(-)](i) affected I(ti) or DAD amplitude. This excludes an important role for I(Cl(Ca)). Blockade of Na(+)/Ca(2+) exchange by substitution of all extracellular Na(+) by Li(+), conversely, completely inhibited I(ti). In rabbit, I(Cl(Ca)) density in ventricular cells isolated from control hearts did not differ significantly from that in ventricular cells isolated from failing hearts. CONCLUSIONS: In contrast to many animal species, I(ti) and DADs in human ventricular cells from failing hearts consist only of I(Na/Ca). In rabbits, heart failure per se does not alter I(Cl(Ca)) density, suggesting that I(Cl(Ca)) may also be absent during DADs in nonfailing human ventricular cells.

Role of Ca(2+)-activated Cl(-) current in ventricular action potentials of sheep during adrenoceptor stimulation.

Adrenoceptor stimulation enhances repolarising and depolarising membrane currents to different extents in cardiac myocytes. We investigated the opposing effects of the repolarising Ca(2+)-activated Cl(-) current (I(Cl(Ca))) and depolarising L-type Ca(2+) current (I(Ca,L)) on the action potential configuration of sheep ventricular myocytes stimulated with noradrenaline. Whole-cell current-clamp recordings revealed that noradrenaline accelerated and prolonged phase-1 repolarisation. We define the minimal potential at the end of phase-1 repolarisation as "notch level". Noradrenaline (1 microM) caused the notch level to fall from 14 +/- 2.6 to 7.8 +/- 2.8 mV (n = 24), but left action potential duration, resting membrane potential or action potential amplitude unaffected. Whole-cell voltage-clamp recordings showed that 1 microM noradrenaline increased both I(Ca,L) and I(Cl(Ca)), but it had no significant effect on the principal K(+) currents. Blockage of I(Cl(Ca)) by 0.5 mM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) in both the absence and the presence of noradrenaline abolished phase-1 repolarisation. In the presence of noradrenaline, DIDS caused elevation of the plateau phase amplitude and an increase in the action potential duration. In conclusion, elevation of the plateau phase amplitude and action potential prolongation associated with an increased I(Ca,L) upon adrenoceptor stimulation is prevented by an increased I(Cl(Ca)) in sheep ventricular myocytes. Experimental Physiology (2001) 86.2, 151-159.