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Biomedical subjects

M G White

Publications and source records attributed to M G White.

At least 37 records · Page 2Linked to original sources
PubMed1986

The absorption of dietary phosphorus and calcium in hemodialysis patients.

Absorption of dietary phosphorus plays a critical role in the development of metabolic bone diseases in patients with chronic renal failure. However, phosphorus absorption is difficult to quantitate in dialysis patients because the dialysis treatments complicate metabolic balance studies. Utilizing a recently developed technique which permits measurement of net absorption of dietary constituents after a single meal, we measured phosphorus absorption in dialysis patients. The following observations were made: A.) Following a meal containing approximately 300 mg phosphorus, mean phosphorus absorption in five hemodialysis patients (with severe vitamin D deficiency) was only slightly less than in matched controls (186 +/- 35 vs. 242 +/- 30). B.) After dialysis patients were treated with 1,25(OH)2-D3, phosphorus absorption increased from 186 +/- 35 to 272 +/- 16 mg (P less than 0.025). C.) The effect of three aluminum containing antacids on phosphorus absorption was studied; each slightly reduced the absorption of phosphorus compared to placebo (P less than 0.01), but there was no significant difference between them. D.) Aluminum hydroxide and calcium carbonate each reduced dietary phosphorus absorption to approximately the same extent. Calcium carbonate ingestion was associated with sharply increased calcium absorption. The absorption of dietary phosphorus is influenced only modestly by 1,25(OH)2-D3 and is inhibited to an equal but only modest degree by various aluminum antacids and by calcium carbonate.

Adult↗
PubMed1985

Proteases in normal and diseased human skeletal muscle: a preliminary histochemical survey.

Seven proteases assumed to be aminopeptidases A, B and M, dipeptidyl peptidases II and IV, esteroproteinase and gamma-glutamyltransferase were localized histochemically, using semipermeable membrane simultaneous coupling techniques, in unfixed cryostat sections of skeletal muscle removed from one healthy volunteer, six patients with disuse muscle atrophy, and 15 patients with some form of muscle disease. Normal muscle fibres showed weak reactions for aminopeptidases A and M and for the dipeptidyl peptidases, but no reactivity for gamma-glutamyltransferase or esteroproteinase. No change was detected in diseased muscle fibres except that low gamma-glutamyltransferase and esteroproteinase activities appeared in some cases. The activities of the seven enzymes were stronger in the intermyosial connective tissue than in the muscle fibres, but were also unchanged in disease. The strongest reactions were found in some interstitial cells (mast cells and macrophages) and these were much increased in diseased muscle, particularly for dipeptidyl peptidases II and IV. The findings are interpreted in terms of the release of proteases from such cells and their subsequent involvement in the breakdown of myofibrillar proteins in muscle disease.

Adolescent↗
PubMed1985

Rat Sertoli cells acquire a beta-adrenergic response during primary culture.

Two-dimensional polyacrylamide gel electrophoresis and the radioligand (-)-[125I]iodopindolol (125I-Pin) have been used to study isoproterenol-dependent protein phosphorylation and beta-adrenergic receptor availability, respectively, in cultured Sertoli cells and freshly isolated seminiferous tubular segments of sexually immature and mature rats. Sertoli cells prepared from sexually immature rats show progressive 125I-Pin binding in primary cultures that correlates with isoproterenol-induced cell shape changes, redistribution of immunoreactive vimentin, and phosphorylation of this intermediate filament protein. The development of 125I-Pin binding to Sertoli cell lysates is blocked by cycloheximide. Seminiferous tubules do not show significant isoproterenol-dependent vimentin phosphorylation nor 125I-Pin binding. However, vimentin phosphorylation can be induced by follicle-stimulating hormone or a cyclic nucleotide analog. This study stresses the need for correlating pharmacological-induced responses observed in Sertoli cell primary cultures with those in the intact seminiferous tubule.

Animals↗
PubMed1984

Lithium intoxication associated with acute renal failure.

Lithium can produce transient natriuresis, nephrogenic diabetes insipidus, and partial distal renal tubular acidosis. Lithium intoxication is commonly associated with mild renal insufficiency and may produce acute renal failure. We have described a case of acute renal failure in a patient with severe lithium intoxication, as well as cardiac arrhythmias and hypothyroidism, both of which have been reported to occur with lithium toxicity. Treatment with daily hemodialysis eventually produced complete recovery. Lithium clearance occurs quickly with hemodialysis, but a rebound effect occurs as lithium in intracellular water equilibrates with extracellular fluid. Prolonged dialysis may be required to reduce the blood lithium level to the therapeutic range. We conclude that lithium intoxication may produce severe reversible renal failure as a result of direct tubular epithelial damage.

Acute Kidney Injury↗
PubMed1982

Structural and functional aspects of cultured epididymal epithelial cells isolated from pubertal rats.

Acidic epididymal glycoprotein (AEG) and androgen-binding protein (ABP) antisera were used to study functional activities of primary cell cultures of the epididymal epithelium of 20--23-day-old rats. Extensive AEG immunoreactivity was associated with almost all epithelial cells of the distal caput, corpus and cauda epididymidis. ABP immunoreactivity was solely confined to some epithelial cells of the caput epididymidis. AEG and ABP immunoreactive cells were identified as principal cells. Morphological studies of enzymically dispersed aggregates of the epididymal epithelial cells showed that stromal cells were satisfactorily removed and that cell aggregates consisted of a predominant population for cells displaying the morphological characteristics of principal cells. Scanning and transmission electron microscopic studies of cultured epididymal epithelial cells in monolayers demonstrated that microvilli and pit-like invaginations of the cell surface were preserved during the first 7--10 days of culture and then gradually disappeared. Other characteristic subcellular structures such as Golgi apparatus and rough endoplasmic reticulum cisterna were preserved. Electrophoretic analysis of [35S]methionine-labelled secretory polypeptides released by epididymal epithelial cells into the culture medium demonstrated a distinct protein band pattern which differed from that observed in the medium of cultured rat Sertoli cells. These results demonstrate that primary cultures of epididymal epithelial cells isolated from sexually immature rats maintain several differentiated characteristics of the intact organ and therefore provide a valuable system for the study of epididymal epithelial cell function.

Androgen-Binding Protein↗
PubMed1976

Reversal of intractable uremic pericarditis by triamcinolone hexacetonide.

Of 74 patients undergoing long-term hemodialysis who were observed during a 21-month period, seven developed uremic pericarditis. Five of these patients developed intractable pericarditis, unresponsive to intensive dialysis and pericardiocentesis, and were treated with prolonged pericardial drainage (16 to 60 hours) by an indwelling polyethylene catheter and instillation of triamcinolone hexacetonide. Evidence of intractability was based on either the recurrence of cardiac tamponade after pericardiocentesis (two patients) or progression in the size of the pericardial effusion despite four weeks of intensive dialysis (three patients). These five patients recovered and subsequently were observed from 1 to 15 months with no evidence of recurrent pericarditis. This procedure may be an effective alternative to the surgical management of intractable uremic pericarditis, particularly in the patient at high risk for anesthesia and major surgery.

Adult↗
PubMed1976

Staphylococcal sepsis in patients on chronic hemodialysis regimens: intravenous treatment with vancomycin given once weekly.

Five patients on chronic hemodialysis regimens were hospitalized with six episodes of Staphylococcus aureus septicemia. Three of the patents acquired the infection during home dialysis, and it was related to the hemodialysis circulatory-access site in four. Initial therapy was methicillin sodium. Vanomycin hydrochloride was given in a 1-gm, single, weekly dose as the sole antibiotic after a short interval (mean, three days). Five of the six episodes were treated successfully. Staphylococcus epidermidis grew in blood cultures obtained during one of the treatments. The advantages of this regimen included a more prompt ambulation and the discontuation of constant infusions in patients with no peripheral veins available.

Adult↗
PubMed1975

Treatment of the syndrome of inappropriate secretion of antidiuretic hormone with lithium carbonate.

Lithium, an established inhibitor of antidiuretic hormone action, was used (as the carbonate salt) to treat a patient with the syndrome of inappropriate secreation of antidiuretic hormone. The patient was studied by balance technics, and after a stablized hyponatremic state developed, 0.9 g of lithium carbonate was administered daily. A prompt water diuresis ensued, with correctionof hyponatremia in two days. Discontinuation of the drug resulted in a gradual return of the hyponatremic state. No change in urinary cyclic AMP occurred during the period of lithium effect. Lithium carbonate may be an effective treatment for both the acute and the chronic forms of the syndrome.

Administration, Oral↗
PubMed1975

Hyperglucagonemia in uremia: reversal by renal transplantation.

Chronic renal failure in man is associated with hyperglucagonemia that is not corrected by hemodialysis. Plasma glucagon concentrations were measured in nine patients before and after renal transplantation. Mean plasma glucagon concentration in eight patients with chronic renal failure before transplantation was 295 plus or minus 171 pg/ml (plus or minus SD). After successful transplantation, mean plasma glucagon concentration fell to 134 plus or minus 81 pg/ml (plus or minus SD) (P less than 0.001). Plasma glucagon concentration remained elevated in an additional patient who received a cadaveric graft that never functioned. Immunologic rejection of transplanted kidneys was associated with a dramatic increase of plasma glucagon concentration.

Cadaver↗
PubMed1974

Hyperglucagonemia of renal failure.

Elevation of plasma glucagon concentration has been observed in starvation and illnesses associated with increased catabolism such as diabetes mellitus and severe infections. Thus, we examined plasma glucose, immunoreactive insulin (IRI, microunits per milliliter) and glucagon (IRG, picograms per milliliter) responses to a beef meal (1 g/kg body wt) and intravenous glucose (1.5 g/min for 45 min) in patients with chronic renal failure (CRF). After the beef meal (n = 6), plasma glucose did not change, IRI rose from 10.1+/-1.2 to 16.3+/-1.1 (P < 0.01), and IRG rose from a fasting value of 225+/-26 to 321+/-40 (P < 0.01) by 90 min (mean+/-SEM). Intravenous infusion of glucose in CRF patients resulted in significant elevations and prolonged disappearance of plasma glucose and insulin when compared to control subjects (P < 0.01). Glucose infusion failed to suppress elevated plasma glucagon concentrations to normal levels.6 wk of chronic hemodialysis in five patients resulted in normal plasma glucose and insulin responses to the same intravenous glucose load. In contrast, plasma glucagon concentration remained unchanged after hemodialysis and there was no correlation of plasma glucagon levels with carbohydrate intolerance.

Adult↗