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Biomedical subjects

P J Tropper

Publications and source records attributed to P J Tropper.

21 records · Page 2Linked to original sources
PubMed1984

The influence of hypermagnesemia on serum calcium and parathyroid hormone levels in human subjects.

We measured serum concentrations of calcium and parathyroid hormone in seven pregnant women who were receiving intravenous magnesium sulfate for the suppression of premature labor. After administration of magnesium sulfate, the mean (+/- S.E.M.) serum magnesium level rose rapidly from the normal base-line level of 2.0 +/- 0.2 mg per deciliter to 6.1 +/- 0.4 mg per deciliter (0.8 +/- 0.1 to 2.5 +/- 0.2 mmol per liter) (P less than 0.001) at 30 minutes and remained markedly elevated. Concentrations of total and ionized calcium fell gradually in all subjects from normal base-line concentrations, 8.6 +/- 0.2 and 4.4 +/- 0.1 mg per deciliter (2.2 +/- 0.1 and 1.1 +/- 0.03 mmol per liter), respectively, into the hypocalcemic range, reaching a nadir of 7.6 +/- 0.2 and 3.9 +/- 0.1 mg per deciliter (1.9 +/- 0.1 and 0.98 +/- 0.03 mmol per liter), respectively, at three hours (P less than 0.001). Parathyroid hormone levels fell rapidly in response to magnesium infusion, from 13.1 +/- 2.5 to 7.8 +/- 0.7 pg per milliliter at 30 minutes, and were significantly below base-line levels for two hours despite frank hypocalcemia. These results suggest that hypermagnesemia rapidly decreases the secretion of parathyroid hormone in vivo in human subjects and that parathyroid hormone levels remain depressed despite concomitant hypocalcemia. The results also suggest that the hypocalcemia associated with hypermagnesemia may be due in part to the suppressive effects of hypermagnesemia on parathyroid hormone secretion.

Adult↗
PubMedDate not supplied

Fetal cardiorespiratory and neurobehavioral response to zidovudine (AZT) in the baboon.

OBJECTIVE: To evaluate the effects of intravenous of zidovudine (AZT) at a dose and duration of infusion comparable to that used clinically on parameters reflective of fetal well-being. METHODS: Thirteen chronically instrumented noninfected baboons were monitored during intravenous infusions of AZT. Fetal cardiorespiratory activity and neurobehavioral function were assessed with 4-48-hour infusion of AZT to ten mothers (0.5-2.1 mg/kg per hour) and three fetuses (2-6 mg/h), which resulted in fetal plasma concentration of AZT of 194-3100 ng/ml. RESULTS: No significant differences were found in the mean values in control periods, before and after infusion with values during infusion for parameters of fetal heart rate and rate variability (n = 7), breathing activity (n = 8), electroencephalographic activity (n = 8), and behavioral state (N = 7). No correlations were found with drug level. CONCLUSIONS: The absence of associations between exposure of the fetal baboon to AZT and changes in parameters reflective of fetal condition suggests that comparable exposure of the human fetus during intravenous infusion of drug would not confound clinical monitoring used to assess fetal well-being. These findings supplement conclusions from clinical research in support of U.S. Public Health Service recommendations that intrapartum fetal monitoring be performed as clinically indicated, not specifically because pregnant patients are treated with intravenous AZT.

Animals↗