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Biomedical subjects

S A Goldberg

Publications and source records attributed to S A Goldberg.

8 recordsLinked to original sources
PubMed1993

Separation of myocardial versus peripheral effects of calcium administration in normocalcemic and hypocalcemic states using pressure-volume (conductance) relationships.

This study used left ventricular pressure-volume (conductance) relationships to separate the effects of calcium administration on myocardial performance and peripheral vasoconstriction in normocalcemic and hypocalcemic states. Hypocalcemia was produced in anesthetized dogs with intravenous citrate-phosphate-dextrose until serum [Ca2+] was approximately 0.7 mmol/L. Calcium (CaCl2) bolus (5 mg/kg) was administered during normocalcemia (n = 6) and hypocalcemia (n = 6), and data were collected at 1, 5 and 10 min after CaCl2 administration. During normocalcemia, CaCl2 administration increased [Ca2+] 19% at 1 min and was accompanied by a 47% (P < 0.05) decrease in left ventricular contractility (i.e., end-systolic elastance or E(lves)) and a 13% (P < 0.05) increase in systemic vascular resistance. At 5 and 10 min, serum [Ca2+] and the hemodynamic variables began to return to the baseline values. During hypocalcemia, E(lves) decreased 25% (P < 0.05), but after CaCl2 bolus, it increased to baseline levels and remained there during the 10-min period. Hypocalcemia and the CaCl2 bolus did not significantly affect SVR. In conclusion, these studies suggest that the indications for the use of calcium should depend on the initial serum level of ionized calcium.

Animals↗
PubMed1992

Lack of increased cardiac output during hemoglobin hemodilution can be reversed with sodium nitroprusside.

To investigate a possible connection between EDRF or nitric oxide (NO) and the unchanged cardiac output (CO) during hemoglobin-hemodilution we infused nitroprusside (NP) in eight Hb-diluted dogs (Hct approximately 20%). Normal hypotensive doses of NP were not effective and supranormal doses (133.0 micrograms/kg/min) were needed to induce even a modest decrease in mean AoP (approximately 25 mmHg). With these NP doses, cardiac output increased 177%, diastolic AoP (afterload) decreased 30%, while systolic AoP and LVEDP (preload) were unchanged. Heart rate, LV contractility (pressure-volume function) and blood volume were not changed throughout the study. Normally, NP alone decreases both preload and afterload resulting in unchanged CO. In the Hb + NP dogs, CO increased because only afterload decreased suggesting a selective effect of Hb on venous and arterial smooth muscle relaxation. In hemodilution with nonhemoglobin colloids, CO increases primarily because the diluted blood offers less viscous resistance to ventricular ejection. It appears that in order for cardiac output to increases in the presence of Hb, some decrease in arteriolar resistance is needed, presumably to unmask the effects of reduced viscosity. These results suggest the unchanged CO during Hb-dilution is related to a selective effect of Hb on venous and arteriolar nitric oxide (EDRF) function.

Animals↗
PubMed1990

The porphyrias.

The porphyrias are a group of metabolic disorders arising from defects in the haem biosynthetic pathway. Most forms are inherited as Mendelian autosomal dominant characters, but some are recessive and others acquired. There is a linked group of diseases, which are not porphyrias, but have in common alterations of haem biosynthesis. The haem biosynthetic pathway is now well understood and the molecular biology of its function and dysfunction in the porphyrias is currently an area of major investigation. The acute porphyrias are of most importance since attacks of these may be life-threatening. A variety of factors may precipitate these attacks including various drugs, alcohol, strict dieting or fasting and hormonal fluctuations. The non-acute porphyrias are largely dermatological conditions, which present clinically as cutaneous photosensitivity. The dermatological changes are brought about by the photosensitizing properties of circulating porphyrins. On the basis of this photoactivity, porphyrins are now being used, therapeutically, in the treatment of cancer.

Acute Disease↗