Viva la VOSCE?

BACKGROUND: The COVID-19 pandemic lockdown precluded face-to-face final Objective Structured Clinical Examinations (OSCE) in the UK. RESULTS: In response, we rapidly developed and then successfully implemented a novel Virtual Objective Structured Clinical Examination (VOSCE). CONCLUSIONS: In this article we both describe and reflect on our experience as well as discuss the implications for future undergraduate assessment as the situation evolves.

Preoperative risk factors in 10 418 patients with prior myocardial infarction and 5241 patients with prior unstable angina undergoing elective coronary artery bypass graft surgery.

BACKGROUND: The EuroSCORE associates coronary artery bypass graft (CABG) surgery with higher perioperative risk in the first 3 months after a myocardial infarction (MI). The optimal scheduling of CABG surgery after unstable angina (UA) is unknown. We investigated the preoperative predictors of adverse outcomes in patients undergoing CABG with prior MI or UA and investigated the importance of time interval between the cardiac event and CABG. METHODS: The Hospital Episode Statistics database (April 2006-March 2010) was analysed for elective admissions for CABG. Independent preoperative patient factors influencing length of stay, readmission rates, and mortality, were identified by logistic regression and presented as adjusted odds ratios (ORs). RESULTS: A total of 10 418 patients with prior MI (mortality 1.8%) and 5241 patients with prior UA (mortality 2.2%) were included in the respective cohorts. Multiple risk factors were identified in each population including liver disease and renal failure. The time interval from cardiac event (MI or UA) to elective CABG surgery did not influence perioperative outcomes when analysed as a continuous measure or using the arbitrary 3-month threshold [MI, OR 1.1 (0.78-1.57) and UA, OR 0.65 (0.39-1.09)]. CONCLUSIONS: Our hypothesis generating data suggest that the increased risk currently allocated in the EuroSCORE for an interval of 3 months between MI and CABG should be critically re-evaluated. Furthermore, prior MI should not be discounted as a risk factor if it is more than 3 months old.

All I want for coagulation.

Evidence-based medicine underpins modern practice of medicine. This paper describes a fictional consultation between Santa Claus and a doctor regarding deep vein thrombosis (DVT) prophylaxis, giving a review of the evidence for DVT prophylaxis in travellers while exposing the difficulty in applying evidence to atypical clinical encounters. Medline and the Cochrane Library were searched, and guidelines reviewed. Keywords used were DVT, thromboembolism, deep vein thrombosis and air travel-related venous thromboembolism. All relevant studies found, have been included in this review, with additional studies identified from the references in these articles. In conclusion, compression stockings, with or without a one-off dose of either aspirin or heparin, are the most evidence-based approaches for prophylaxis in someone with established risk factors for DVT prior to a long-haul flight. Simple exercises should also be encouraged.

Equality of access to "fast-track" stroke services in an older, socio-economically deprived Scottish population.

BACKGROUND AND AIMS: Unequal access to specialist stroke services may contribute to the disproportionate stroke burden in certain populations. We evaluated the relationship between access to TIA services, deprivation and age. METHODS: We prospectively recorded referral pattern data on consecutive TIA service patients. Socio-economic deprivation was derived from postcode and census data. Associations were described using Kruskal-Wallis statistics. RESULTS: Of 3,462 patients assessed, there was no association between time to clinic referral or attendance and increasing deprivation or age. CONCLUSION: Inequality of access to TIA services for older, deprived patients was not evident. However, delay to assessment and prevalence of risk factors was substantial for all patients.

Acute medicine teaching in an undergraduate medical curriculum: a blended learning approach.

BACKGROUND: Acute medical management is an important component of the Modernising Medical Careers (MMC) project which has recently been implemented in the UK. A web-based interactive course in acute medicine has been developed which complements the clinical teaching provided to senior medical students at the University of Glasgow. A study was undertaken to evaluate the teaching and assess the knowledge of acute medicine among final year medical students using an online questionnaire. METHODS: The undergraduate medical school Virtual Learning Environment (VLE) was constructed using the Moodle learning management system. The online questionnaire was constructed as part of the interactive acute medicine course hosted on the VLE. Final year students using this course were asked to complete the questionnaire anonymously. A 5-point Likert scale was used to assess different aspects of acute medical management and evaluate the teaching. RESULTS: From 210 students using the website, 99 (47.1%) completed the online questionnaire. Nephrology and neurology were identified as the most challenging specialties in acute medicine. The areas of acute management in which students felt they lacked most knowledge were drug overdose and acute renal failure. Drug prescribing was also identified as an area of the curriculum requiring further development. CONCLUSIONS: This approach to blended learning is popular with our medical students. Online evaluation has helped with curriculum development and, by identifying important areas of acute medicine teaching that can be improved, is feeding into our curriculum revision.

Effect of vitamin D status on the equilibrium between occupied and unoccupied 1,25-dihydroxyvitamin D intestinal receptors in the chick.

The dynamic equilibrium between in vivo occupied and unoccupied 1,25-dihydroxyvitamin D(3)[1,25(OH)(2)D(3)] receptors of the chick intestinal mucosa was investigated by the exchange assay previously reported [(1980). J. Biol. Chem.255: 9534-9537]. These parameters and their correlation to biological response, i.e., the levels of intestinal vitamin D-dependent calcium binding protein (CaBP), were assessed under different physiological conditions. After a single 1,25(OH)(2)D(3) injection (3.25 nmol), occupied receptor levels increased sharply to a maximum between 1 and 2 h, followed by a rapid decline. A single dose of 1alpha-hydroxy-vitamin D(3) [1alpha(OH)D(3)], an analog that requires 25-hydroxylation for biological activity, resulted in a protracted, albeit lower, response with maximal receptor occupancy at 6 h and half maximal levels 24 h after injection. The intestinal receptor occupancy patterns mirrored the serum 1,25(OH)(2)D(3) levels after either 1,25(OH)(2)D(3) or 1alpha(OH)D(3) treatment. Additionally, time-course (half-life) of blood disappearance of 1,25(OH)(2)D(3) and occupied receptor levels were similar (1.9 and 2.3 h, respectively), suggesting that the amount of occupied 1,25(OH)(2)D(3) receptor is determined by a simple equilibrium between serum 1,25(OH)(2)D(3) and unoccupied receptors. A dose-response study after intramuscular 1,25(OH)(2)D(3) injection yielded a hyperbolic curve with an apparent plateau at 70% receptor occupancy, corresponding to 5 nmol 1,25(OH)(2)D(3) injected. Half-maximal occupancy was reached after a dose of 1 nmol 1,25(OH)(2)D(3), corresponding to 1.5 ng 1,25(OH)(2)D(3)/ml serum. From this value the apparent K(d) in vivo is 3.7 nM, which is similar to that determined in vitro. A 10-fold increase in the 1alpha(OH)D(3) dose resulted in less than a doubling of the levels of serum 1,25(OH)(2)D(3), occupied 1,25(OH)(2)D(3) receptors, or CaBP. Under all experimental conditions, there was a positive correlation between occupied receptor and CaBP levels; however, the slope of the lines depended on the times chosen for the assays due in part to the lag period for CaBP induction and its accumulation within the cell. Conversely, the correlation between serum 1,25-(OH)(2)D(3) levels and occupied receptor levels yielded a single regression line independent of the observation time. Short and long-term treatment with different vitamin D metabolites, estrogen, progesterone, or cortisol did not affect the levels of total intestinal 1,25(OH)(2)D(3) receptor. Under normal physiological conditions, only 10-15% of the total 1,25(OH)(2)D(3) receptor population was occupied by ligand. These studies provide a basis for further investigations of physiological and biochemical parameters of the vitamin D endocrine system and their clinical applications.

The prognostic significance of visible infarction on computed tomography following lacunar stroke: results of a long-term follow-up study.

BACKGROUND AND PURPOSE: Substantial variability in functional outcome and relatively few factors predictive of death or degree of recovery have been observed in patients with lacunar stroke. Such indicators are of great use in the selection of optimal rehabilitation strategies after stroke. Although computed tomography (CT) of patients with a clinical diagnosis of lacunar stroke performed within the first 10 days shows evidence of cerebral infarction in 50% to 60%, the prognostic significance of a visible ischemic lesion on CT is unclear. METHODS: 633 patients who presented with symptoms consistent with lacunar stroke between June 1990 and February 1998 were studied. One hundred fourteen patients imaged with magnetic resonance, 41 patients with nonischemic diagnoses (hemorrhage or tumor), 57 patients imaged within 12 hours of ictus, and 17 patients with incomplete follow-up were excluded from the analysis. The remaining 404 patients were divided into 2 groups, depending on the appearance of the CT scan. Patients with a low-attenuation area on the CT scan consistent with an ischemic lesion in an appropriate region of the brain to explain the presenting symptoms were classified as "CT positive." Patients with either a normal CT scan of the brain or a scan that showed a lesion in an area inconsistent with the presenting symptoms were classified as "CT negative." A series of known or suspected prognostic factors were recorded for each patient: blood pressure, age, smoking, plasma glucose level, serum cholesterol level, and serum triglyceride level. Delay from stroke onset to scanning was also noted. The authors considered 3 outcome measures: survival time, outcome at 6 months after the stroke, and total length of hospital stay for the stroke admission. Six-month outcome was categorized as good (alive at home) or poor (alive in care or dead). RESULTS: There was no difference in survival between the 2 groups (P= .29, log-rank test). After adjusting for other significant prognostic factors (age; relative hazard per additional decade 1.67, P< .0001: plasma glucose level; relative hazard per additional mmol/l 1.08, P= .03) in a proportional hazards model, presence of visible infarction remained nonsignificant (relative hazard 0.84, P= .40). After adjustment for the other significant factor (age, P= .0001), there was no significant difference in 6-month outcome between CT positive and CT negative patients (P= .61). Median total length of hospital stay was not significantly different between the 2 groups (CT positive, 9 days; CT negative, 8 days; Mann-Whitney test, P= .29). CONCLUSION: The authors conclude that in their cohort of patients, having corrected for other prognostic variables, the presence of visible infarction on CT brain scan performed between 12 hours and 30 days of onset of lacunar symptoms is not predictive of duration of hospital stay or of longer term outcome.

Absence of calbindin-D28 expression in nonclassical 1,25-dihydroxyvitamin D targets: analysis by polymerase chain reaction.

CaBP-D28 mRNA expression in rat heart, testis, and lung was assessed by polymerase chain reaction (PCR). The animal model used was the hyperinduced vitamin D-treated rat (100 ng 1,25-dihydroxyvitamin D subcutaneously, daily for 7 days). For the PCR studies, two pairs of 20 mer oligonucleotide primers (designated 1-4 according to their position on the coding strand, but with primers 3 and 4 in reverse orientation) derived from the rat CaBP-D28 cDNA sequence were tested in various combinations. Optimal conditions were established using a 1:100 dilution of cDNA from normal rat kidney. Bands of the predicted sizes of 869 (1, 3), 994 (1, 4), 725 (2, 3), and 850 (2, 4) nucleotide base pairs resulted, but with varying intensities: 2,4 approximately 1,3 > 1,4 > 2,3. Repeat PCR (recycling after 1:100 dilution and readdition of reagents and primers with at least one different primer) provided strong additional amplification, particularly with the 1,4/2,4 combination. Under these conditions, mixing experiments showed that CaBP-D28 transcripts were detectable at 10(-7)- to 10(-9)-fold lower levels of expression than in D+ kidney. When RNA was isolated and cDNA generated from test tissues from 4 individual vitamin D-stimulated (D+) and vitamin D-deficient (D-) rats, repeat PCR (1,4/2,4 primer combination) provided no evidence of significant CaBP-D28 mRNA expression in the nonclassic target tissues, in contrast to strong bands in both the D- kidney (undiluted) and D+ kidney (1:100 dilution) preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Normocalcemia without hyperparathyroidism in vitamin D-deficient rats.

Despite numerous attempts, no reliable dietary regimen exists to achieve vitamin D deficiency (-D) in rats without attendant changes in plasma parathyroid hormone (PTH), Ca, or phosphate. This represents an important obstacle to proper investigations of the physiologic role(s) of vitamin D metabolites in the function of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] target tissues. This paper describes the successful development of such a diet, which uses a combination of high Ca content, properly controlled Ca/P ratio, and lactose. Normal weanling rats were fed diets containing A, 0.8% Ca, 0.5% P, +D3, or -D diets containing B, 0.8% Ca and 0.5% P; C, 2.0% Ca and 1.25% P; or D, 2.0% Ca, 1.25% P, and 20% lactose. After 6 diet weeks group D rats remained normocalcemic and normophosphatemic, but diet groups B and C became hypocalcemic (6.9 +/- 0.8 and 7.2 +/- 0.4 mg/dl, respectively). Thus high dietary Ca and P was incapable of maintaining normal plasma Ca levels in the absence of dietary lactose. The normocalcemia in group D was not maintained by elevated PTH secretion because N-terminal PTH levels were also normal (14 +/- 3 versus 20 +/- 5 pg/ml). In contrast, PTH levels were markedly elevated in hypocalcemic groups B and C (47 +/- 7 and 48 +/- 10 pg/ml, respectively). Plasma 25-OHD3 and 1,25-(OH)2D3 levels were reduced to less than 120 and less than 12 pg/ml, respectively, in all -D groups. Thus the high-Ca diet and the use of normal weanlings did not impede the development of vitamin D deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Homologous up-regulation of vitamin D receptors is tissue specific in the rat.

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) receptors (VDR) are expressed in multiple tissues within the body. VDR levels are increased by 1,25(OH)2D3 in intestine and kidney and in numerous cell models. The ability of 1,25(OH)2D3 to affect VDR levels in other target tissues in vivo was studied by assessing VDR levels by the 3H-1,25(OH)2D3 binding assay under varied physiological conditions in the rat. When compared with vitamin D-deficient (-D) controls, rats raised on a normal vitamin D-sufficient (+D) diet showed elevated VDR levels in kidney (391 +/- 53 vs. 913 +/- 76 fmol/g of tissue;p < 0.05), but not in testis, heart, or lung. Up-regulation of the VDR also occurred in kidney of +D rats 1 day after a single 100-ng dose of 1,25(OH)2D3 (454 +/- 43 vs. 746 +/- 113 fmol/mg of DNA; p < 0.05), but no changes were seen in intestine, testis, or lung. Because 1,25(OH)2D3-induced hypercalcemia may independently affect VDR regulation, 1,25(OH)2D3 was infused into -D rats, and normocalcemia was maintained by reduced dietary calcium intake. In this model, the renal VDR was again up-regulated (446 +/- 115 vs. 778 +/- 58 fmol/mg of DNA; p < 0.05), but VDR levels in testis and lung were unaffected. Scatchard analysis and tests of 1,25(OH)2D3 dose (1-100 ng/day for 7 days) and temporal (100 ng/day for 1-7 days) responsiveness further supported the tissue-specific nature of the homologous VDR regulation. Assay of VDR levels by L-1-tosylamido-2-phenylethyl chloromethyl ketone-3H-1,25(OH)2D3 exchange assay ruled out differences in endogenous 1,25(OH)2D3 occupancy as the basis for the observed differences in VDR regulation. Finally, coidentity of the VDR-like sites in kidney versus testis was confirmed by competitive binding analysis comparing their relative affinities for 25(OH)D3 versus 1,25(OH)2D3 (30.5 +/- 6.4 vs. 35.6 +/- 3.6 in kidney and testis, respectively) and by immunoblot analysis using a highly specific monoclonal anti-rat VDR antibody. Thus, under a wide variety of experimental conditions, homologous up-regulation of the VDR occurs in the rat kidney in vivo, but not in several other target tissues which do not regulate plasma calcium homeostasis. Moreover, this differential VDR regulation did not result from secondary changes in plasma calcium, from differential 1,25(OH)2D3 responsiveness in the various tissues, nor from differences in endogenous 1,25(OH)2D3 occupancy of the VDR. These studies thus establish that, in contrast to observations in vitro, the widely described phenomenon of homologous VDR up-regulation in kidney and intestine is not a universal property of 1,25(OH)2D3 target tissues in vivo in the rat.

1,25-dihydroxyvitamin D3 receptors in the seminiferous tubules of the rat testis increase at puberty.

Whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptor levels correlate with the rapid in vivo growth rate of the testes in the prepubertal rat was examined. Low salt chromatin-localized 1,25-(OH)2D3 receptors were compared in the testes and intestinal mucosa (control) of prepubertal, peripubertal, and mature rats (37, 49, and 90 days old, respectively). The number of 1,25-(OH)2D3 receptors per g wet wt was significantly (P less than 0.02) reduced in the testes of the prepubertal rats compared to those in the peripubertal and mature groups. Conversely, no changes were observed in the 1,25-(OH)2D3 receptor levels in the control tissue intestinal mucosa among these age groups. Further experiments confirmed the identity of the testicular 1,25-(OH)2D3 receptors. The specific [3H]1,25-(OH)2D3-binding component was predominantly localized in the nuclei/chromatin fraction in hypotonic buffers. Scatchard analysis of [3H]1,25-(OH)2D3 binding to the testicular chromatin of adult rats yielded a single specific binding component with a Kd of 0.33 +/- 0.06 nM and a Nmax of 102.3 +/- 6.4 fmol/g tissue (n = 6), which was inhibited by excess 1,25-(OH)2D3, but only minimally by 50 nM 25-hydroxyvitamin D3. Sucrose gradient analysis required hydroxylapatite treatment of fractions after centrifugation to remove free 3H-labeled steroid. With this modification, a discrete 3.6S peak of [3H]1,25-(OH)2D3 was unmasked, which was eliminated by excess 1,25-(OH)2D3, but not by 50 nM 25-hydroxyvitamin D3, or 1 microM cortisol, or the progesterone analog promegestone. In spite of its seemingly ubiquitous distribution, the 1,25-(OH)2D3 receptor does exhibit tissue specificity, since it appears to be absent in the prostate and, at best, greatly reduced in the epididymis. The cellular localization of the testicular 1,25-(OH)2D3 receptors was examined by mechanically separating interstitial cells (93.7% of the total [125I]hCG binding) from the tubules. Under these conditions, 91.3% of the specific [3H]1,25-(OH)2D3 binding occurred in the tubular chromatin preparation. Thus, these data provide evidence for the presence of a specific 1,25-(OH)2D3 receptor in the seminiferous tubules of the rat testis. Moreover, the temporal correlation of increased 1,25-(OH)2D3 receptor levels with testicular maturation suggests a better correlation to testicular function and spermatogenesis than to growth of the organ in vivo.

Stoichiometric translocation of the rat uterine progesterone receptor.

In several previous studies nuclear accumulation of the progesterone receptor was significantly lower than the quantity depleted from the cytosol one h after progesterone injection. The results presented herein indicate that this apparent lack of stoichiometry is due to loss of detectable receptor from the nucleus during the nuclear washes and after the assay incubation. This decrease in measured receptor results both from solubilization of the receptor-progesterone complex into the supernatant and from dissociation of [3H] ligand from the receptor. Conversely, no significant quantities of receptor were detected in the mitochondrial/microsomal fraction, preincubation nuclear washes, second ethanol extraction of the nuclear pellet, and soluene digest of the extracted pellet. Thin layer chromatography of the radioactive ligand bound to the nuclear receptor after in vitro exchange confirmed that virtually all the specific binding was due to [3H] progesterone, in spite of a 30% conversion to other metabolites in the incubation fluid.

Rat uterine progesterone receptor analyzed by [3H]R5020 photoaffinity labeling: evidence that the A and B subunits are not equimolar.

The hormone-binding components of the rat uterine progesterone receptor were investigated by the methods of [3H]R5020 photoaffinity labeling and sodium dodecyl sulfatepolyacrylamide gel electrophoresis analysis. Two specifically labeled peaks were observed at mol wt of 85,600 +/- 1,200 and 109,600 +/- 1,200 (n = 31), resembling the A and B progesterone receptor components previously described in other systems. However, in contrast to the equimolar ratio reported in other systems, the level of subunit A observed was consistently greater than that of B (A/B ratio = 3.2 +/- 0.3; n = 31). The unusual A/B ratio prompted a complete validation of the photolabeling procedure in this system. Although the levels of specific binding increased, there was no change in the A/B ratio with varying [3H]R5020 concentrations (5-80 nM) or with time of UV exposure (0.5 min to 3 h). Although adsorption to hydroxylapatite indicated that specific [3H]R5020 binding was reduced by 72.0 +/- 6.4% within 5 min of UV exposure, relabeling the irradiated preparations with [3H]R5020 resulted in little change in specific [3H]R5020 binding. TLC analysis of [3H]R5020 (Rf = 0.48 +/- 0.01; n = 4) after irradiation demonstrated rapid photolysis resulting in a 94.3 +/- 2.5% (n = 3) loss of authentic [3H]R5020 within 5 min. After photolysis, at least two new tritiated products were recovered with Rf values of 0.20 +/- 0.03 and 0.72 +/- 0.02. Analysis by adsorption to hydroxylapatite indicated that the photolysis products competed for specific [3H]R5020-binding sites in cytosol with only 10-fold lower relative binding activity than authentic R5020. Thus, these compounds probably account for the increase in specific photolabeling of the A and B peaks achieved when UV exposure is prolonged from 5 to 30 min. Further study indicated that the A/B subunit ratio in this system was not changed under a variety of in vitro conditions, including the absence or presence of molybdate, sulfhydryl protective reagents (dithiothreitol and thioglycerol), protease inhibitors (phenylmethylsulfonylfluoride and leupeptin), glycerol (0%, 10%, and 30%, vol/vol), or 1.5 mM EGTA, or after precipitation with 40% ammonium sulfate. This consistency of the A/B ratio under a wide variety of adverse in vitro conditions suggests that in vitro artefacts may not account for the ratio's deviation from unity. Estrogen withdrawal (48 h) enhanced by progesterone treatment (0.5 mg for 24 h) resulted in only a modest reduction in the A/B ratio to 1.9 +/- 0.1.(ABSTRACT TRUNCATED AT 400 WORDS)

Protracted 1,25-dihydroxyvitamin D treatment stimulates multiple calmodulin binding proteins in rat kidney.

Previous studies demonstrated that 1,25-dihydroxyvitamin D [1,25-(OH)2D] treatment in vivo stimulates [125I]calmodulin (CaM) binding to several proteins (detected by [125I]CaM gel overlay) in cytosol preparations from rat kidney. This study establishes the sizes of the principal stimulated forms and physiological aspects of their stimulation by the hormone. Densitometric analysis of the 1,25-(OH)2D-stimulated [125I]CaM binding activities demonstrated induction of two major bands, M(r) = 110 +/- 2.4 and 94 +/- 1.2 K. This analysis also revealed induction of a previously existing band at 150 +/- 2.7 K and induction of a 74 +/- 1.1 K band. 1,25-(OH)2D-induction of the [125I]CaM binding activities (CaMBP-Ds) was observed in both vitamin D-deficient and normal vitamin D-sufficient rats. The [125I]CaM binding activities were abolished by incubation with 1000-fold excess CaM, but not calbindin-D28, troponin C, parvalbumin, or alpha-lactalbumin. 1,25-(OH)2D induction of the [125I]CaM binding activities exhibited a graded dose response at 5-100 ng/day, and 5-7 days treatment was required for strong induction. The [125I]CaM binding activities in the kidney exhibited differential subcellular distributions: 150 K CaMBPs were present in crude preparations of nuclei, microsomes, and mitochondria; a 110 K CaMBP was present in the microsomal preparation; and the 94 and 74 K CaMBPs were restricted to the cytosol. 1,25-(OH)2D treatment resulted in the induction of the microsomal 110 K CaMBP and possibly the nuclear (but not in mitochondrial or microsomal) 150 K CaMBPs. In conclusion, there are at least four 1,25-(OH)2D-induced [125I]CaM binding activities in the rat kidney, with some variations in subcellular distribution. Moreover, their pattern of induction suggests that 1,25-(OH)2D regulation of the [125I]CaM binding activities is not a part of the immediate 1,25-(OH)2D signal transduction pathway, but rather may result from altered genomic activity after hormone treatment.

Sugar and amino acid transport from the rat uterine lumen: effects of estrogen and progesterone.

Sugar and amino acid transport and diffusion from the uterine lumen were evaluated in either castrated rats 4 or 24 h after iv injection of 17 beta-estradiol (0.1--10 microgram) or in estrogen-primed castrated rats 12 or 24 h after iv injection of progesterone (25--250 microgram). Uptake phenomena were evaluated by selectively exposing the uterine luminal surface to a Ringer's solution containing [U-14C]D-mannitol and [3H]3-O-methyl-D-glucose or [3H]alpha-aminoisobutyric acid for a 30-sec incubation. Diffusion (D-mannitol uptake) decreased significantly 4 h (but not 24 h) after estrogen and 12 and 24 h after progesterone treatment. [3H]3-O-methyl-D-glucose transport increased significantly both 4 h (120--380%) and 24 h (50--200%) after estrogen. Although [3H]3-O-methyl-D-glucose transport was not significantly changed from that in the vehicle-injected control 12 or 24 h after progesterone, comparison of the transport at 12 h (reduced) to that at 24 h (increased) revealed a significant difference in the responses to progesterone treatment at these two times. [3H]alpha-aminoisobutyric acid transport increased significantly 4 and 24 h after only a pharmacological dose of 17 beta-estradiol and was unchanged 24 h after progesterone administration. In summary, uterine luminal diffusion and transport phenomena are hormone sensitive, with estrogen exerting a more pronounced effect on transport than does progesterone. Thus, through modulation of luminal transport mechanisms, these hormones may regulate substrate levels and, hence, their availability to the developing conceptus during different reproductive states in the rat.

Effect of perindopril on cerebral and renal perfusion in stroke patients with carotid disease.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the effect of the angiotensin-converting enzyme inhibitor perindopril on mean arterial blood pressure (MABP), cerebral blood flow (CBF), and glomerular filtration rate in hypertensive stroke patients with moderate to severe internal carotid artery (ICA) disease or ICA occlusion. METHODS: Twenty-four nonacute ischemic stroke patients who had MABP readings >100 mm Hg and moderate to severe ICA stenosis or occlusion were randomized to receive perindopril 4 mg daily or placebo for 14 days. MABP, ICA flow, and both middle cerebral artery (MCA) velocity and resistance index were measured before dose, at 5 time points over the subsequent 24 hours, and finally at 2 weeks. Brain hexamethyl propylene amine oxide single photon emission computed tomography scans were performed before drug administration and at time of peak drug effect (6 to 8 hours) after the first dose. Glomerular filtration rate was measured with (51)Cr EDTA before medication and at 14 days. RESULTS: A placebo-corrected BP fall of 17/10 mm Hg was seen (P:=0.017), which was maximal at 5.5 hours. No significant change in ICA flow or MCA velocity was seen between groups. No significant change in hemispheric CBF was seen. The mean change from baseline in the treated group was -0.79 mL. 100 g(-1). min(-1) (95% confidence interval [CI], 1.65 to -3.23); mean change in the placebo group was -1.9 mL. 100 g(-1). min(-1) (95%CI, 3.02 to -6.92). Peri-infarct CBF was similarly unaffected. One of the treated patients developed transient acute renal impairment and was withdrawn from the study on day 4. CONCLUSIONS: Perindopril lowers BP without lowering CBF in hypertensive stroke patients with moderate to severe ICA stenosis or occlusion; monitoring of this patient population for the complications of renal artery stenosis should be considered.

Identification of environmental chemicals with estrogenic activity using a combination of in vitro assays.

Environmental chemicals that function as estrogens have been suggested to be associated with an increase in disease and dysfunctions in animals and humans. To characterize chemicals that may act as estrogens in humans, we have compared three in vitro assays which measure aspects of human estrogen receptor (hER)-mediated estrogenicity. Chemicals were first tested for estrogen-associated transcriptional activity in the yeast estrogen screen (YES). This was created by expressing hER and two estrogen response elements linked to the lacZ gene in yeast. Second, chemicals that were tested in YES were then assayed for direct interaction with hER in a competition binding assay. Third, chemicals were tested in the estrogen-responsive MCF-7 human breast cancer cell line transiently transfected with a plasmid containing two estrogen response elements linked to the luciferase gene. Together, these assays have identified two metabolites of DDT, o,p'-DDD and p,p'-DDD, that have estrogenic activity. Interestingly, previous studies had reported that the DDD metabolites were nonestrogenic in whole animal models. Alachlor, the most frequently used herbicide in the United States, cis-nonachlor, and trans-nonachlor displayed weak estrogenic activity in the combined assays. The antifungal agent benomyl had no estrogenic activity. We propose that a combination of in vitro assays can be used in conjunction with whole animal models for a more complete characterization of chemicals with estrogenic activity.

Deficiency of vitamin D metabolites directly stimulates renal 25-hydroxyvitamin D3-1-hydroxylase activity in rats.

Renal 25-hydroxyvitamin D3-1-hydroxylase (1-hydroxylase) enzyme activity in rats is known to be increased by parathyroid hormone (PTH), hypophosphatemia, and hypocalcemia. Thus, enzyme activity is markedly increased in vitamin D-deficient states, but whether this stimulation is a direct response to the vitamin D deficiency or only occurs following the associated changes in plasma calcium, phosphate, or PTH is unclear. We tested whether vitamin D deficiency per se influences 1-hydroxylase activity in renal cortical slices using a normocalcemic rat model of vitamin D deficiency. Weanling male rats were fed one of the following three diets: (A) 0.8% Ca, 0.5% P, 2.2 IU vitamin D3/g; or vitamin D-deficient diets containing, (B) 0.8% Ca, 0.5% P; and (C) 2.0% Ca, 1.25% P, 20% lactose. Vitamin D-deficient rats fed diet B were hypocalcemic with elevated PTH at both test periods, and 1-hydroxylase activity was increased more than 100-fold compared with rats fed diet A. Plasma calcium, phosphate, and PTH levels were the same in groups A and C, but 1-hydroxylase activity was also substantially elevated in group C versus group A rats (104- and 17-fold increases after 10 and 19 diet weeks, respectively). These data lead to the important conclusion that severe deficiency of vitamin D metabolites per se provides a strong and independent stimulus to renal 1-hydroxylase activity in rats, perhaps due to the absence of 1,25(OH)2D3-mediated enzyme inhibition.

Specific 1,25-dihydroxyvitamin D3 binding sites in choroid plexus.

Quantitative autoradiographic analysis of [3H] 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) binding in vitamin D deficient mice provided evidence for high levels of specific binding in choroid plexus and, to a lesser extent, ventral hippocampus. Sucrose gradient analysis yielded a 3-4S peak of specific [3H]1,25(OH)2D3 binding in bovine choroid plexus, but not amygdala or hippocampus. Scatchard analysis of [3H]1,25(OH)2D3 binding in bovine choroid plexus yielded KD = 0.23 +/- 0.06 nM and Nmax = 43.5 +/- 0 fmol/g tissue (n = 5). This result indicates the presence of significant receptor-like [3H]1,25(OH)2D3 binding sites in the choroid plexus and, thus, suggests roles for this hormone in regulating the entry of calcium into the brain and/or in the central regulation of calcium homeostasis.

On the crisis in biomedical education: is there an overproduction of biomedical PhDs?

The United States is the world leader in biomedical science (BMS) education and research. This preeminence is reflected in superior medical education, the attraction of U.S. educational institutions to foreign visitors seeking advanced training, and a high rate of transfer of knowledge between basic biomedical research and the delivery of health care at the bedside. The foundation for this excellence and leadership has been the research carried out by MD and PhD biomedical scientists. It has been suggested that there is now an oversupply of BMS PhDs, and thus that BMS PhD programs should be downsized. Full examination of the issues involved, including a case study of doctoral graduates and postdoctoral fellows at Tulane Medical Center, leads the authors to conclude that a biomedical PhD "glut" does not exist at the present time, that downsizing training programs would have a serious, long-term negative impact on biomedical research, and that medical school administrators and faculty should resist attempts to reduce biomedical research and training at the local and national level. However, times have changed and training programs must evolve to adapt to the technologic changes occurring in the workplace. Alternatives, such as new alliances with industry, must be sought to compensate for decreased resources at federal and institutional levels; new and innovative curricula must be developed to prepare biomedical scientists for nonacademic, as well as academic, job opportunities in the twenty-first century; and medical center administrators and faculties must work together to increase the visibility of BMS and stress its critical relationship to the research base of the nation.