Biomedical subjects

R N Burch

Publications and source records attributed to R N Burch.

4 recordsLinked to original sources

PubMed1982

Renal function studies in man with advanced renal insufficiency.

In subjects with advanced renal insufficiency, the average of the creatinine and urea clearances ([Ccr + Cur]/2) is frequently used as an indicator of glomerular filtration rate (GFR). To test the accuracy of this method, 31 subjects with inulin clearance (Cin) less than 20 ml/min/1.73 m2 underwent simultaneously timed creatinine, urea, and inulin clearances. The results indicated that: (1) Ccr correlated positively with Cin; mean fractional excretion of creatinine (Ccr/Cin) was 1.5; (2) Cur correlated positively with Cin; in contrast to creatinine, the fractional excretion of urea (Cur/Cin) correlated negatively with Cin; (3) in 10 of 12 subjects with Cin less than 8 ml/min 1.73 m2, the Cur/Cin was greater than 1, suggesting that tubular secretion may have occurred; and (4) the (Ccr + Cur)/2 correlated positively with Cin and was the best clinical indicator of GFR.

Adult↗

PubMed1982

Clinical appraisal of creatinine clearance as a measurement of glomerular filtration rate.

The plasma creatinine and the endogenous creatinine clearances are two of the most commonly used tests in clinical medicine to assess glomerular filtration rate. However, the contribution that tubular secretion of creatinine has on the total endogenous creatinine clearance (Ccr) is not generally known, nor are the effects renal insufficiency has on the tubular secretion of creatinine. To assess the above, 123 human subjects, with a wide range of renal function, underwent simultaneous Ccr and inulin clearances (Cin). The results indicate that: (1) Ccr approximates Cin only when Cin is normal; (2) a normal plasma creatinine of Ccr is not measurable evidence of a normal Cin; and (3) with progressive decline in Cin, there is progressive increase in the tubular secretion of creatinine, leading to a progressive disparity between Ccr and Cin.

Adult↗

PubMed1982

Renal function and hemodynamic studies in low- and normal-renin essential hypertension.

Reduced renal blood flow has been suggested to be both a cause and a consequence of essential hypertension. To test these hypotheses, techniques for the clearance of inulin (Cin) and p-aminohippurate (Cpah) were used to assess renal function and hemodynamic measurements in patients with mild and moderate normal-renin and low-renin essential hypertension and in age-matched normotensive subjects. In our study, compared with age-matched control subjects, normal-renin hypertensive subjects younger than 42 years with basal diastolic BPs less than 100 mm Hg had normal glomerular filtration (Cin) and effective renal plasma flow (Cpah), filtration fraction (Cin/Cpah), and renal blood flow (Cpah/1-hematocrit value). The mean arterial pressure (MAP) and renal vascular resistance (MAP/renal blood flow) were increased. In contrast, compared with age-matched control subjects, normal-renin hypertensive subjects older than 42 years with basal diastolic BPs less than 100 mm Hg and greater than 100 mm Hg had a decreased Cpah and an increased filtration fraction. The MAP was increased, the renal blood flow decreased, and the renal vascular resistance notably increased. Subjects with low-renin essential hypertension had renal function and hemodynamic patterns indistinguishable from those of age matched normal-renin hypertensive subjects with similar basal diastolic BPs. These data suggest that in early normal-renin essential hypertension, the increase in systemic BP is not caused by renal circulatory disturbances. Increased renal vascular resistance, however, may lead to subsequent vascular functional or structural changes, ultimately decreasing effective renal plasma flow but at a rate disproportionate to the glomerular filtration rate.

Adult↗

PubMed1981

Effects of diuretic and propranolol on plasma lipoprotein lipids.

Ticrynafen (TCNF), a nonthiazide diuretic, has been reported to be nonhyperlipidemic. To define the effects of these drugs on plasma lipoproteins, experiments were performed in hypertensive subjects after placebo therapy, 4 wk after therapy with either hydrochlorothiazide (HCTZ) or TCNF, 3 mo after diuretic with propranolol, and 1 mo after therapy with propranolol alone. Plasma lipoproteins were separated by ultracentrifugation and the lipid fractions isolated by extraction and silicic acid thin-layer chromatography. Plasma low-density lipoprotein (LDL) total cholesterol fell and high-density lipoprotein (HDL) total cholesterol rose in subjects receiving TCNF. TCNF had no effect on plasma low-density lipoprotein (VLDL) triglyceride or phospholipid. There was no significant changes in LDL or HDL total cholesterol in subjects on HCTZ. HCTZ tended to increase plasma VLDL triglyceride and phospholipid. The addition of propranolol to either diuretic had no effect on LDL or HDL total cholesterol but increased VLDL triglyceride, especially in subjects on HCTZ. Propranolol alone had no effect on any of the lipids measured.

Adult↗