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Biomedical subjects

D G Sapir

Publications and source records attributed to D G Sapir.

27 records · Page 2Linked to original sources
PubMed1972

The effect of carbohydrates on ammonium and ketoacid excretion during starvation.

The metabolic effects of oral ingestion of minute quantities of carbohydrate during prolonged starvation were studied in nine obese subjects. Measurements were made during a control period of total starvation, during the ingestion of 7.5 g carbohydrate daily, and finally during the ingestion of 15.0 g carbohydrate daily. Daily ketoacid excretion fell after carbohydrate ingestion and was significantly correlated (r = 0.62, P < 0.01) with the amount of carbohydrate administered. Despite this fall in ketoacids, the concentration of blood ketoacids, plasma free fatty acids, and serum insulin remained constant throughout the study. Urinary ammonium excretion, closely correlated with ketoacid output (r = 0.95, P < 0.001), also fell significantly after carbohydrate ingestion. No significant changes were present in extracellular or urinary pH. Urea nitrogen excretion did not change when urinary ammonium output fell. These results indicate that: the excretion of ketoacids and ammonium in starving man is exquisitely sensitive to minute amounts of ingested carbohydrate; the change in ketonuria appears to be due to increased renal ketoacid reabsorption after carbohydrate ingestion; and the nitrogen-sparing effect of reducing renal ammonium output in starvation can be dissociated from nitrogen sparing occurring because of changes in urine urea excretion.

Adolescent↗
PubMed1967

The effects of chronic hypoxemia on electrolyte and acid-base equilibrium: an examination of normocapneic hypoxemia and of the influence of hypoxemia on the adaptation to chronic hypercapnia.

We have carried out balance studies in normal dogs in order to appraise the effects of chronic hypoxemia on acid-base and electrolyte equilibrium. During the first phase of observation we produced a state of "pure" hypoxemia by reducing the oxygen concentration (utilizing nitrogen as a diluent) and by adding carbon dioxide to the environment in a concentration sufficient to keep arterial CO(2) tension (PCO(2)) within normal limits. The data demonstrate that such a 9-day period of normocapneic hypoxemia has no effect on electrolyte excretion and is virtually without effect on plasma composition. During the second phase of observation we subjected the hypoxemic dogs to stepwise increments in arterial carbon dioxide tension in order to evaluate the effects of the low oxygen tension on the acid-base adjustments to a chronic state of hypercapnia. At least 6 days was allowed for extracellular composition to reach a new steady state at each level of inspired carbon dioxide. The data demonstrate a rise in both plasma bicarbonate concentration and renal acid excretion that was not significantly different from that which has been described previously for hypercapnia without hypoxemia. Just as in these earlier studies, plasma hydrogen ion concentration rose with each increment in carbon dioxide tension, each millimeter Hg increment in PCO(2) leading to an increase in hydrogen ion concentration of 0.32 nmole per L. It thus appears that the chronic"carbon dioxide response curve" is not significantly influenced by moderately severe hypoxemia.

Acid-Base Equilibrium↗
PubMedDate not supplied

Case report. Unilateral renal vein thrombosis without proteinuria.

Unilateral renal vein thrombosis occurred in a patient who was found to have an adenocarcinoma and who had previously been subjected to trauma. Proteinuria was absent throughout the patient's entire clinical course, despite its well known association with renal vein thrombosis. However, other findings suggestive of renal vein thrombosis, including back pain and tenderness, hematuria and an enlarged kidney were present. It is clear that proteinuria need not be the only signal to occasion a search for renal thrombosis. This case probably constitutes the second report of absent proteinuria when thrombus forms within renal vein.

Adenocarcinoma↗
PubMedDate not supplied

Acute renal failure. Community hospital experience with hemodialysis as intensive care adjunct.

A 3-year experience with 50 acute renal failure patients managed by hemodialysis in a 417-bed community hospital is reviewed. The 58% survival rate was better than that reported in other recent series. Possible reasons for our favorable mortality experience include: (1) Hemodialysis was performed within the ICU facility by the ICU staff. Continuity of total care was thereby maintained and hemodialysis problems, such as maintenance of circulating volume, were managed in the context of continued assessment of the patient's cardiopulmonary status. (2) In contrast to previous reports, the presence of sepsis did not influence recovery rates from acute renal failure. Early administration of specific antibiotics, mainly gentamicin, rapid drainage of abdominal abscesses, and early and frequent dialysis were all utilized in spetic patients and may have contributed to their high recovery rate. (3) The use of agressive dialysis may also have lessened other uremic complications, notably gastrointestinal bleeding. Our dialysis organization and procedures are described.

Acute Kidney Injury↗
PubMedDate not supplied

Evidence for an anabolic action of essential amino acid analogues in uremia and starvation.

Nitrogen-free analogues of essential amino acids, when administered with those essential amino acids for which analogues are ineffective or unavailable, exert three actions that may be beneficial in protein-deficient or protein-intolerant subjects. First, they bring about an increase in the concentrations of essential amino acids in the blood at the expense of the concentrations of certain non-essential amino acids, notably alanine and glutamine. This effect is most readily demonstrated in children with congenital defects of the urea cycle enzymes, but can also be seen during daily therapy of adults with portal-systemic encephalopathy. Second, these compounds promote nitrogen balance through their suppressive effect on urea synthesis (an effect not attributable to re-utilization of ammonia derived from urease action in the gut). This action is demonstrable in obese subjects who are already conserving nitrogen maximally at the end of a prolonged fast and can also be shown in the first week of fasting when the branched-chain keto acids alone are administered. In both situations, improved nitrogen conservation persists long after the analogues are metabolized, suggesting enzyme adaptations. In chronic uremics, nitrogen balance can be maintained in some (but not all) patients on very low nitrogen intakes. Third, these mixtures may delay or reverse the progressive decline in glomerular filtration rate characteristic of chronic renal failure in some cases: thus, for example, 5 of 6 patients taken off chronic dialysis have maintained lower serum urea concentrations without evidence of protein malnutrition for periods of 2-24 months.

Amino Acids↗