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Biomedical subjects

S Massry

Publications and source records attributed to S Massry.

8 recordsLinked to original sources
PubMed1998

Creatinine clearance as a measure of GFR in screenees for the African-American Study of Kidney Disease and Hypertension pilot study.

Serum creatinine and endogenous creatinine clearance (CrCl) are widely used measures of renal function. This study compares the precision, bias, and sources of error in using different CrCl measures to estimate the glomerular filtration rate (GFR) in 118 men and women screened for the African-American Study of Kidney Disease and Hypertension (AASK) pilot study. We measured serum creatinine, 24-hour CrCl, and CrCl during timed clearance periods conducted simultaneously with an 125I-iothalamate GFR study. Serum creatinine was measured using two different kinetic rate Jaffe methods (CX3 and Hitachi). After standardization for body surface area, the different measures of renal function available for each individual were compared with the 125I-iothalamate GFR simultaneous to the CrCl. In a subset of 50 participants, the CrCl measures were compared with a follow-up GFR (fGFR). The mean 125I-iothalamate GFR was 65.2 (SD, 26.4), with a range of 11 to 122 mL/min/1.73 m2. The mean +/- SD percentage differences from the GFR were -9%+/-22% for the Cockcroft-Gault estimated CrCl, 1%+/-29% for the 24-hour CrCl, and 8%+/-16% for the CX3 simultaneous CrCl. The Hitachi method overestimated serum creatinine and underestimated GFR. Compared with an fGFR, the mean +/- SD differences were 2%+/-19% for the first GFR, -6%+/-20% for the Cockcroft-Gault estimated CrCl, 10%+/-28% for the 24-hour CrCl, and 14%+/-29% for the CX3 simultaneous CrCl. Thus, the increased precision with which the timed CrCl predicted its simultaneous GFR did not extend to improved ability to predict a future GFR. The fractional excretion of creatinine, measured as the ratio of the CX3 simultaneous CrCl to 125I-iothalamate clearance, increased with decreasing GFR but was lower than expected (mean +/- SD of 1.21+/-0.16 for GFRs between 20 and 40 mL/min/1.73 m2). The lower fractional excretion explains why the 24-hour and Cockcroft-Gault CrCls did not overestimate GFR, but the reasons for this lower excretion are uncertain. Creatinine assay specificity and calibration are important sources of variability that must be examined in any CrCl measure of GFR. We conclude that despite requiring substantially more time and effort, neither the outpatient 24-hour urine nor the timed CrCl offered increased precision over a calculation based on serum creatinine, sex, age, and weight in predicting GFR.

Black People↗
PubMed1998

Mechanisms and clinical significance of cell volume regulation.

A wide variety of factors challenge constancy of cell volume. Alterations of cell volume activate diverse cell volume regulatory mechanisms including ion transport, osmolyte accumulation, metabolism and expression of appropriate genes. A wealth of cellular signalling pathways link cell volume to the respective regulatory mechanisms. Cell volume emerges as a pathophysiologically important parameter in several diseases including diabetes mellitus, uraemia, hepatic insufficiency and hypercatabolic states. The role of altered cell volume in disease is a challenge which requires more experimental research and clinical investigation.

Animals↗
PubMed1977

Muscle water and electrolytes in uremia and the effects of hemodialysis.

The effects of acute uremia and hemodialysis on water and electrolyte distribution and intracellular pH (pHi) of skeletal muscle were studied in dogs. Acute uremia resulted in an increase in intracellular muscle water and Ca++ content, and a fall in both intracellular Na+ concentration and the calculated muscle membrane potential (EM). Muscle pHi did not change. The increase in muscle Ca++ content was prevented by previous parathyroidectony. The administration of parathyroid extract to previously parathyroidectomized uremic animals resulted in a rise in muscle Ca++ content to levels similar to those observed in intact uremic animals. Hemodialysis with standard dialysate resulted in a normalization of both muscle Em and Ca++ content but did not affect either muscle intracellular water, Na+ concentration, or pHi. Hemodialysis with hypertonic dialysate (glycerol or mannitol) resulted in a slight fall in intracellular muscle water content toward normal but did not change muscle intracellular Na+ concentration or pHi. The muscle membrand permeability of Na+ relative to K+ (PNa/PK) was not changed by hemodialysis with either standard dialysate or dialysate with mannitol added. Glycerol, however, appeared to increase PNa/PK to about 10 times the normal value. The observed changes in muscle water and solute content may be related to the increased muscle irritability seen in acute uremic patients. These changes, however, are only partially corrected by hemodialysis with standard or hypertonic dialysate.

Animals↗