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Biomedical subjects

E Weinman

Publications and source records attributed to E Weinman.

10 recordsLinked to original sources

Regulation of the renal Na(+)-H+ exchanger by calcium calmodulin-dependent multifunctional protein kinase II.

Prior studies indicate that cAMP-dependent protein kinase (PKA) and calcium calmodulin-dependent multifunctional protein kinase II (CaM-KII) inhibit Na(+)-H+ exchanger as assayed in octyl glucoside solubilized rabbit renal brush border membrane proteins reconstituted into artificial lipid vesicles. An anion exchange chromatography fraction of these proteins which elutes between 0.2 and 0.4 M NaCl (Fraction B), however, fails to demonstrate regulation of the transporter by PKA. The present studies examine regulation of the Na(+)-H+ exchanger by CaM-KII using Fraction B proteins. As compared to the initial total protein extract, Fraction B demonstrated increased Na(+)-H+ exchange activity. CaM-KII inhibited the Na(+)-H+ exchanger in Fraction B by 38.2 +/- 10.6% in an ATP and calmodulin-dependent manner. The results of the present studies suggest that CaM-KII-mediated inhibition of the Na(+)-H+ exchanger involves the phosphorylation of different polypeptides than those mediating the inhibition of this transporter by PKA.

Adenosine Triphosphate↗

Prolonged dietary protein restriction in diabetic nephropathy.

Eleven patients with insulin-dependent diabetes, advancing renal insufficiency, and proteinuria were placed on a diet containing 0.6 g/kg per day of high-biologic-value protein. Selected clinical variables were observed over a 2-year interval. The rate of decline in renal function was significantly decreased during the intervals of protein restriction. The rate during the second 12 months of the study, however, was increased, when compared with the first 12-month interval. Urinary protein excretion decreased significantly, from 2.27 +/- 0.49 g/d to 0.57 +/- 0.40 g/d after the first 12 months of the study, but increased to 1.43 +/- 0.63 g/d after the second 12 months of the study. The dietary protein intake estimated from urea nitrogen excretion in urine samples correlated significantly with urinary protein excretion. These findings suggest that dietary protein restriction has a sustained beneficial effect on the course of diabetic nephropathy, if compliance to the diet can be maintained.

Adult↗

Renal adenocarcinoma and end stage kidney disease.

The association of end stage kidney disease with cystic degeneration and renal adenocarcinoma was first recognized in 1977. Since then a number of reports have confirmed this relationship. Duration of dialysis has been the most strongly associated risk factor. We report 8 cases of end stage kidney disease and renal adenocarcinoma. Median duration of hemodialysis was approximately 1 year, and 3 patients never had hemodialysis. Factors other than duration of dialysis, such as toxic metabolites, toxins from dialysis tubing, polyamines or other carcinogens, may be as or more important.

Aged↗

Suppurative bacterial pyelonephritis as a cause of acute renal failure.

Acute oliguric renal failure associated with bacterial pyelonephritis is a rarely recognized clinical entity. We report a woman with an ectopic pregnancy who developed acute renal failure requiring dialytic support. The renal biopsy revealed focal microabscess formation and leukocyte interstitial infiltration compatible with suppurative pyelonephritis. Although her renal function improved gradually with antimicrobial treatment, the process was incomplete and renal dysfunction persisted at a 10-week follow-up, suggesting permanent renal damage.

Acute Kidney Injury↗

Transluminal dilatation of the subclavian artery.

Transluminal dilatation of seven left subclavian arteries and one right subclavian artery was attempted in seven patients. Dilatation was successful in four left subclavian arteries and the single right subclavian artery treated. Five of the patients suffered from cerebral symptoms as well as ischemia of the upper limb, one had only cerebral symptoms and another had only arm claudication. All patients also had significantly reduced systolic blood pressures in the brachial artery. Standard techniques for percutaneous transluminal angioplasty (PTA) were employed, using the femoral route six times and the axillary route four times. No complications occurred. All patients were permanently given a maintenance dose of antiplatelet treatment with dipyridamole 75 mg tds after PTA. Follow-up of up to 36 months, indicates that angioplasty can be accomplished in the stenosed subclavian artery with relatively little hazard. Patients with hemodynamically significant stenoses should be considered for PTA if their symptoms and signs warrant such therapy.

Adult↗

The effects of ionizing irradiation on production of thromboxane and prostacyclin by the isolated perfused rat kidney.

Exposure to whole body radiation is associated with prompt changes in urinary excretion of prostaglandins. We investigated the separate effects of radiation on rat kidney capillary and tubular system prostaglandin synthesis. Animals were irradiated to the left kidney area with a single dose of 15 Gy. One week later the rats were anesthesized, the renal artery, vein and ureter of the left kidney cannulated, and the kidney removed and perfused with Krebs-Henseleit physiological buffer at a rate of 10-12 ml/min. Effluent fluids were collected separately from the renal vein and from the ureter of irradiated and control (operated sham-irradiated animals) and were assayed by radioimmunoassays for thromboxane A2 (TXB2) and prostacyclin (6 keto PGF1 alpha). Histological examination of the irradiated kidneys showed no significant changes, and electron microscopy revealed minimal interstitial edema. In contrast to these minimal changes, TXB2 assays showed a significant increase both in the venous and ureter effluents. Following stimulation with angiotensin II in the perfusate, a further significant increase in TXB2 production was observed both by the capillary and the tubular systems. With 6 Keto PGF1 a slightly different response was seen. The basal production was increased only in the ureter effluent of the irradiated animals, while there were no changes in the release in the venous effluents. In parallel, radiation significantly increased the angiotensin II stimulated production capacity of prostacyclin by the tubular system. The response of the capillary system following irradiation may create imbalance between these two important substances and lead to the radiation effects in the renal tissue.

Animals↗