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Biomedical subjects

A E Broadus

Publications and source records attributed to A E Broadus.

115 records · Page 7Linked to original sources
PubMed1970

Kinetic parameters and renal clearances of plasma adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in man.

Kinetic parameters and the renal clearances of plasma adenosine 3',5'-monophosphate (cyclic AMP) and guanosine 3',5'-monophosphate (cyclic GMP) were evaluated in normal subjects using tritium-labeled cyclic nucleotides. Each tracer was administered both by single, rapid intravenous injection and by constant intravenous infusion, and the specific activities of the cyclic nucleotides in plasma and urine were determined. Both cyclic AMP and cyclic GMP were cleared from plasma by glomerular filtration. The kidney was found to add a variable quantity of endogenous cyclic AMP to the tubular urine, amounting to an average of approximately one-third of the total level of cyclic AMP excreted. Plasma was the source of virtually all of the cyclic GMP excreted. Plasma levels of the cyclic nucleotides appeared to be in dynamic steady state. The apparent volumes of distribution of both nucleotides exceeded extracellular fluid volume, averaging 27 and 38% of body weight for cyclic AMP and cyclic GMP, respectively. Plasma production rates ranged from 9 to 17 nmoles/min for cyclic AMP and from 7 to 13 nmoles/min for cyclic GMP. Plasma clearance rates averaged 668 ml/min for cyclic AMP and 855 ml/min for cyclic GMP. Approximately 85% of the elimination of the cyclic nucleotides from the circulation was due to extrarenal clearance.

Adenine Nucleotides↗
PubMed1970

Effects of glucagon on adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in human plasma and urine.

Glucagon, infused intravenously into fasting, well-hydrated, normal men in doses of 25-200 ng/kg per min, induced up to 30-fold increases in both plasma and urinary cyclic AMP. Cyclic GMP levels were unaffected by glucagon. Simultaneous cyclic AMP and inulin clearance studies demonstrated that the glucagon-induced increase in urinary cyclic AMP was entirely due to glomerular filtration of the elevated plasma levels of the nucleotide. The cyclic AMP response to glucagon was not mediated by parathyroid hormone or epinephrine, and trypsintreated glucagon was completely inactive. The perfused rat liver released cyclic AMP into the perfusate in response to glucagon, indicating that the liver is a possible source of the cyclic AMP entering the extracellular fluids in response to glucagon in vivo.

Adenine Nucleotides↗
PubMed1970

Effects of parathyroid hormone on plasma and urinary adenosine 3',5'-monophosphate in man.

The effects of parathyroid hormone (PTH) on plasma and urinary adenosine 3',5'-monophosphate (cyclic AMP) levels were studied in normal subjects. Under basal conditions normal adults have plasma concentrations of cyclic AMP ranging from 10 to 25 nmoles/liter and excrete from 1.5 to 5 mumoles of cyclic AMP per g of urinary creatinine. About one-half to two-thirds of the cyclic AMP excreted in the urine is derived from the plasma by glomerular filtration, and the remainder is produced by the kidney. Renal production of cyclic AMP is partly under the control of PTH. It can be suppressed by infusions of calcium and stimulated by infusions of the calcium chelating agent, EDTA. Infusions of PTH in doses up to 10 mU/kg per min were associated with dose-related increases both in urinary cyclic AMP and phosphate. Infusions of PTH in doses ranging from 20 to 80 mU/kg per min did not lead to any further increase in phosphaturia but did lead to further marked increases in urinary cyclic AMP. A modest increase in plasma cyclic AMP was noted when PTH was infused at 40 mU/kg per min. Anephric patients failed to show appreciable increases in plasma cyclic AMP in response to large doses of PTH but did show expected increases in response to glucagon. Surgical removal of parathyroid adenomas from nine patients with primary hyperparathyroidism was invariably followed by a decrease in urinary cyclic AMP, PTH, in large doses, and calcium infusion produced up to 2-fold increases in the other known naturally occurring cyclic nucleotide, guanosine 3',5'-monophosphate (cyclic GMP).

Adenine Nucleotides↗
PubMedDate not supplied

The regional educational impact of a Renal Stone Center.

This study evaluates the impact of the Renal Stone Center (RSC) at Yale University School of Medicine on the extent of the diagnostic search for urolithiasis risk factors at the Yale-New Haven Medical Center and four affiliated community hospitals. Using a multiple time series design and a Physician Performance Index (PPI) based on multiple normative practice criteria, the hospital and outpatient charts of 1,924 patients with a primary diagnosis of urolithiasis at the five hospitals were examined to determine whether there was a change over time that could be related to the RSC. There was no statistically significant improvement in the PPI at four of the five hospitals. At the fifth, there was a statistically significant improvement that possibly was related to factors other than the RSC. Routine blood, urine, and X-ray tests usually were performed well. However, the history of urolithiasis risk factors and the examination of 24-hour urines were generally done poorly or not at all, and this generalization held true (although modified somewhat) even when physician office records were examined as well.

Ambulatory Care↗
PubMedDate not supplied

The diagnostic evaluation of risk factors for urinary tract stones: an analysis of care patterns in five hospitals.

Medical records of hospitalized primary urolithiasis patients in five Connecticut hospitals were studied to determine the aggressiveness of the diagnostic search for metabolic and other renal stone risk factors. A total of 924 patients over three years were analyzed. Routine serum, urine, and X-ray tests were generally performed according to accepted criteria. However, medical histories were generally inadequate, and 24-hour urine studies for calcium and uric acid were performed on less than half of the patients for whom they were indicated. Neither the complexity of the stone problem nor the stone event number appeared to influence the intensity of the diagnostic search in any important way. Other deficiencies included the lack of followup of abnormal test findings and the lack of treatment of problems discovered. The diagnostic approach in each hospital was stable over time.

Calcium↗