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M Geheb

Publications and source records attributed to M Geheb.

10 recordsLinked to original sources
PubMed1991

Endocrine crises. Hypophosphatemia and hyperphosphatemia.

Pathophysiology, clinical sequelae, and treatment for hypophosphatemia and hyperphosphatemia are discussed. Hypophosphatemia results from a variety of conditions including malnutrition, carbohydrate refeeding, acid-base disorders, and hormonal and drug effects. Patients suffering from severe hypophosphatemia may present with a variety of syndromes that can become detrimental and even life-threatening if this electrolyte depletion goes untreated. Hyperphosphatemia occurs because of increased extracellular phosphate load from either endogenous or exogenous sources or from a decrease in renal phosphate excretion. Left untreated, hyperphosphatemia can result in dangerous calciumphosphate precipitation into vital organs and tissues.

Aged↗
PubMed1988

Lithium-induced renal disease: a prospective study.

Considerable controversy exists as to whether lithium maintenance therapy is associated with the development of renal insufficiency. In 1980 we initiated a prospective study of renal function in manic-depressive patients beginning lithium therapy. None of the patients had evidence of pre-existing renal disease. Sixty-five patients were entered, and 51 and 18 patients completed 1 and 3 years of follow-up, respectively. Lithium doses were titrated to the lowest level consistent with control of psychiatric symptoms; there were no episodes of overt lithium intoxication. Serum creatinine levels in all patients, and endogenous creatinine clearance in women, remained stable over the course of the study. In contrast, creatinine clearances (mean +/- SEM, ml/min/1.73 m2) in men significantly decreased over both 1 year (110 +/- 4 to 95 +/- 5, n = 21, p = 0.0126) and 3 years (107 +/- 4 to 80 +/- 11, n = 8, p = 0.0385) of evaluation. Although all patients demonstrated a mild reduction in renal concentrating ability after initiation of lithium, the decrease was not progressive over the course of the study. Quantitative urinary protein excretion did not change, and repeated urinalyses did not reveal any evidence of renal disease. Thus, lithium therapy appears to result in modestly reduced rates of glomerular filtration, as measured by endogenous creatinine clearance, in men receiving lithium maintenance therapy for manic-depressive illness. Whether this reduction is progressive and leads to clinically significant renal insufficiency requires further investigation.

Adult↗
PubMed1984

Steroid-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders. Correlation with natriferic activity.

We have identified a group of proteins (Mr approximately 70 000-80 000; pI approximately 5.5-6.0) in giant-toad (Bufo marinus) urinary bladders whose synthesis appears to be related to aldosterone-stimulated Na+ transport. Spironolactone, a specific mineralocorticoid antagonist in renal epithelia, inhibits the synthesis of these proteins as well as the natriferic effect of the hormone. Since a variety of other steroids (some of which are traditionally considered to be glucocorticoids) also stimulate Na+ transport in toad urinary bladders, we examined whether their natriferic activity was expressed in a fashion similar to that of aldosterone. Short-circuit current was used to measure Na+ transport, and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. At a concentration of approximately 100 nM, dexamethasone, corticosterone and aldosterone were equinatriferic. Dexamethasone and aldosterone had identical dose-response curves, maximal and half-maximal activity being evident at concentrations of approximately 100 nM and 10 nM respectively. In contrast, at a concentration of approximately 10 nM, corticosterone had no effect on Na+ transport. The natriferic activities of these three steroids correlate with their known affinities for the putative mineralocorticoid receptor in toad urinary bladders. Natriferic concentrations of dexamethasone and corticosterone (140 nM) induced the synthesis of proteins with characteristics identical with those induced by aldosterone. Spironolactone, at an antagonist/agonist ratio of 2000:1, inhibited steroid-induced Na+ transport and the synthesis of these proteins. Thus it appears that all natriferic steroids share a common mechanism of action in toad urinary bladders. Natriferic activity can be correlated not only with relative steroid-receptor affinity but also with the induction of a specific group of epithelial-cell proteins.

Aldosterone↗
PubMed1983

Mineralocorticoid-specificity of aldosterone-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders.

We have identified a group of proteins (Mr approximately 70000-80000; pI approximately 5.8-6.4) in giant-toad (Bufo marinus) urinary-bladder epithelial cells whose synthesis appears to be related to aldosterone-stimulated Na+ transport. To define this relationship further, we examined whether submaximal natriferic concentrations of aldosterone induced these proteins and whether spironolactone (a specific mineralocorticoid antagonist in renal epithelia) inhibited their synthesis. Short-circuit current was used to measure Na+ transport and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. Submaximal natriferic concentrations of aldosterone (1.4 X 10(-8) M) induced the same proteins as maximal concentrations of the hormone (1.4 X 10(-7) M). In contrast, in previous experiments, similar proteins were not induced by subnatriferic concentrations (5.0 X 10(-8) M) of cortisol, a glucocorticoid. A spironolactone/aldosterone molar ratio of 2000:1 was required to inhibit aldosterone-stimulated Na+ transport completely; ratios of 200:1 and 500:1 produced partial inhibition. Concentrations of spironolactone that abolished aldosterone-stimulated Na+ transport also inhibited aldosterone-induced protein synthesis. We conclude that the synthesis of the proteins we have identified is specifically related to activation of the mineralocorticoid pathway.

Aldosterone↗
PubMed1982

Aldosterone-induced proteins in renal epithelia.

Similar aldosterone-induced proteins have been demonstrated in two renal epithelia, the urinary bladder of the toad, Bufo marinus, and epithelia formed by cells of the A6 line derived from the kidney of the toad, Xenopus laevis. The proteins are induced along with the stimulation of Na+ transport but their synthesis is not dependent on Na+ transport per se. In view of the similar characteristics of the aldosterone-induced proteins in these two different epithelia, we suggest that they may have an important role in aldosterone-induced Na+ transport.

Aldosterone↗
PubMed1981

Aldosterone-induced proteins in toad urinary bladders. Identification and characterization using two-dimensional polyacrylamide gel electrophoresis.

Aldosterone-stimulated Na+ transport is mediated by new protein synthesis, but the identification of specific aldosterone-induced proteins (AIPs) has proven difficult and the cellular function of such proteins is unknown. Using high resolution two-dimensional polyacrylamide gel electrophoresis and autoradiography we have identified AIPs of similar isoelectric points (5.8 to 6.4) and molecular weights (70,000 to 80,000) in membrane-rich and cytosolic subcellular fractions of epithelial cells derived from single toad urinary bladders. The ability of actinomycin D to inhibit both AIP synthesis and aldosterone-induced Na+ transport is consistent with a role for these proteins in the natriferic action of aldosterone. In addition, since non-natriferic concentrations of cortisol did not induce similar proteins, AIP synthesis appears to be mineralocorticoid-specific. The relationship of AIP synthesis to Na+ transport was also studied. Since amiloride, which blocks Na+ transport in high resistance epithelia, did not affect the synthesis of these proteins, Na+ transport is not required for their synthesis. In addition, similar proteins were not induced when Na+ transport was stimulated by antidiuretic hormone and theophylline. Consequently, AIP synthesis is not merely a nonspecific consequence of the cellular metabolic changes associated with Na+ transport.

Aldosterone↗
PubMed1981

Subcellular localization of aldosterone-induced proteins in toad urinary bladders.

Paired toad urinary hemibladders were incubated with [35S]methionine in the presence (experimental) or absence (control) of aldosterone. Short-circuit current was used to monitor aldosterone-induced Na+ transport. Protein synthesis in epithelial cell subcellular fractions (cytosolic, microsomal, mitochondrial) was evaluated by gradient polyacrylamide gel electrophoresis and autoradiography. Aldosterone-induced proteins were identified in the cytosolic and microsomal fractions (70 000 and 15 000 daltons, respectively). These results represent the first demonstration of aldosterone-induced proteins in subcellular fractions of epithelial cells derived from single toad urinary hemibladders.

Aldosterone↗
PubMedDate not supplied

Measurement and improvement of humanistic skills in first-year trainees.

The American Board of Internal Medicine (ABIM) has recently emphasized the development of humanistic skills in trainees. Using video technology, transition outpatient visits of first-year house officers in a primary care training program were evaluated for the presence or absence of nine humanistic skills before and after the initiation of an instructional program to reinforce the skills. Thirteen videotaped PGY-1 encounters constituted the preintervention group and 16 videotaped PGY-1 encounters constituted the postintervention group. The preintervention group performed a mean of 1.38 skills while the postintervention group performed a mean of 3.56 skills, a statistically significant improvement (p less than 0.05). The authors conclude that an educational approach that focuses on specific elements of interactions facilitates the incorporation of skills associated with humane medical care.

Clinical Competence↗