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Biomedical subjects

P Churchill

Publications and source records attributed to P Churchill.

43 records · Page 3Linked to original sources
PubMed1979

Sodium-chloride-induced protection in nephrotoxic acute renal failure: independence from renin.

It has been shown that the severity of experimentally induced acute renal failure (ARF) is inversely related to dietary sodium chloride intake, and the effects have been attributed to the concurrent changes in renal renin. In the current study, renal renin of rats was increased by chronic sodium deprivation and decreased by chronic sodium loading and DOCA administration. In two nephrotoxic models (mercuric chloride, uranyl nitrate), giving previously sodium-deprived rats 1% sodium chloride to drink for 48 hours prior to ARF induction greatly attenuated the severity without any reduction in their high renal renin. Conversely, giving previously sodium-loaded rats tap water to drink for 4 to 5 days prior to AFR induction greatly enhanced the severity without any increase in their subnormal renal renin. Therefore, the changes in severity of ARF resulting from changes in dietary sodium are not mediated by changes in renal renin. Significant inverse correlations were found between mean peak BUN values during the follow-up period (5 to 7 days) and the 24-hour urinary sodium excretions prior to ARF induction in both models, suggesting that sodium intake and/or excretion at the time of induction is a good predictor of the severity. The effects of sodium chloride in both models were predominantly expressed during the maintenance phase, and consisted of attenuation of the severity (both models) and hastening of the recovery (mercuric chloride model). Possible mechanisms by which dietary sodium produced its effects, independently of its effects on the renin-angiotensin system, are discussed.

Acute Kidney Injury↗
PubMed1978

Natriuresis-induced protection in acute myohemoglobinuric renal failure without renal cortical renin content depletion in the rat.

The interrelationships of renal cortical renin content RCRC, sodium chloride excreting and the severity of renal failure were studied in the glycerol-induced acute myohemoglobinuric renal failure model in the rat. Protocols were designed to increase sodium chloride excretion without necessarily resulting in RCRC depletion. Our data fail to demonstrate a relationship between RCRC and severity of renal failure, but they demonstrate an excellent inverse correlation between the sodium chloride excretion of the animals in the 24 h prior to glycerol administration and the severity of resulitng renal failure. The protection of long-term saline-drinking animals should properly be ascribed to the associated natriuresis which develops much before RCRC depletion during the time course of saline drinking. The exact mechanism by which natriuresis exerts its protective effect needs further elucidation, but our data argue against a major role for RCRC in the pathogenesis of acute experimental renal failure.

Acute Kidney Injury↗
PubMed1977

Glycerol-induced acute renal failure in the two kidney Goldblatt rat.

One to four weeks after the left renal artery was clipped and the contralateral kidney was left untouched in Sprague-Dawley rats (two-kidney Goldblatt preparation), the clips were removed under ether anesthesia and 10 ml/kg body wt of either 150 mM NaCl (control) or 50% glycerol in water (experimental) were injected intramuscularly. The next day the rats were anesthetized (sodium pentobarbital) and the renal function of both kidneys was measured, after which the renal cortical renin content was measured by incubation of tissue homogenate with angiotensinase-free rat renin substrate. Radioimmunoassay was used to determine the rate of angiotensin I production. Compared with controls, both kidneys of glycerol-injected rats had reduced GFR (left 28, right 18% of controls), increased percentage of fractional water excretion (left 5, right 6 times controls), and increased percentage of fractional Na excretion (left 3, right 4 times controls). Despite large differences in renal renin (left 28, 676, right 1,329 ng angiotensin I/h per mg protein), the extent of renal failure produced by glycerol was equal in the left and right kidneys. These results are inconsistent with the hypothesis that renal renin content is directly related to the severity of glycerol-induced renal failure in rats.

Acute Kidney Injury↗
PubMedDate not supplied

Purification and characterization of D-beta-hydroxybutyrate dehydrogenase expressed in Escherichia coli.

D-beta-Hydroxybutyrate dehydrogenase (BDH), a lipid-requiring enzyme, has been cloned into pUC18, expressed in Escherichia coli, and purified to homogeneity. The apoenzyme, i.e., the enzyme devoid of phospholipid, has no activity, but can be activated by phospholipid to a specific activity of 129 mumol/(min.mg). The functional properties of the enzyme expressed in E. coli were compared with the enzyme purified from rat liver. The specific activities, kinetic parameters, and phospholipid activation profiles were virtually identical. These results indicate that the expression of the enzyme in E. coli is a viable method for producing active functional BDH and should allow for the production of specifically altered BDH molecules.

3-Hydroxybutyric Acid↗