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Biomedical subjects

R A Chez

Publications and source records attributed to R A Chez.

At least 73 records · Page 4Linked to original sources
PubMed1985

The frequent occurrence of false-positive results in phleborheography during pregnancy.

In this study, none of 25 pregnant women without any past history of venous thromboembolic disease had a positive phleborheogram sometime during their pregnancy or within six weeks post partum. In contrast, zero of ten nonpregnant women, also screened for venous thrombophlebitis, had a positive test finding during the same time interval. No clinical parameters, including weight gain, leg circumference, leg swelling, development of varicose veins, leg pain or use of support stockings, correlated with the occurrence of a positive test result. While there is conflicting evidence from other studies, our data suggest the need for caution in interpreting a positive phleboroheogram as an accurate indicator of thrombophlebitis in pregnant women.

Adult↗
PubMed1984

Variations of biologic activity of low-dose prostaglandin E2 on cervical ripening.

The effect of low-dose prostaglandin E2 vaginal gel specially prepared from commercially available materials, on subsequent indicated oxytocin induction of labor, was investigated in a randomized, double-blind, placebo-controlled clinical trial. The stability of the gel after preparation was documented by radioimmunoassay in vitro. No differences between the treated and placebo groups were noted in subsequent modified Bishop scores, length of labor, use of analgesia or anesthesia, success of induction, mode of delivery, or perinatal outcome. Comparisons of this clinical trial with those previously reported are offered.

Adult↗
PubMed1981

Effects of maternal acetonuria and low pregnancy weight gain on children's psychomotor development.

Data were analyzed from a large prospective study to determine if children had an excess of psychomotor or IQ impairment when their mothers had eight acetonuria, weight loss, or low weight gain during pregnancy. The effects of these maternal factors on children's development were assessed by a variety of mental and motor tests from the newborn period to 7 years of age. No consistent impairments were found at any age.

Body Weight↗
PubMed1980

Effect of alpha-adrenergic agonist and antagonist infusion on the umbilical and uterine circulations of pregnant sheep.

The effects of the alpha-adrenergic agonists, norepinephrine and methoxamine, and the alpha-antagonist, phenoxybenzamine, on umbilical and uterine blood flows, fetal and maternal heart rates, arterial and venous pressures were examined in near-term chronic sheep preparations. Norepinephrine injection or methoxamine infusion to either fetus or ewe resulted n a respective unilateral fetal or maternal pressur response associated with bradycardial. Uterine blood flow decreased significantly with alpha-agonist administration to either fetus or ewe. Umbilical blood flow did not change with either, but an increase in calculated umbilicalo vascular resistance did occur after fetal administrations of the alpha-agonist. Thus, both the uterine and umbilical vascular beds are responsive to alpha-agonism, but maternal uteroplacental perfusion appears to be more sensitive. alpha-Blockade in either fetus or mother produced no significant changes in umbilical or uterine blood flows or fetal or maternal perfusion pressure suggesting that basal alpha-adrenergic tone is unnecessary for normal maintenance of either fetal or maternal uteroplacental circulation.

Adrenergic alpha-Agonists↗
PubMed1980

The effect of SAR1ALA8 AII on ovine uterine and umbilical blood flow.

The effects of Sar1Ala8 AII (Saralasin), an angiotensin II (AII) receptor blocker, were examined in the late gestation ewe and fetus. Maternal administration of Saralasin resulted in a reduction in both mean maternal systemic arterial pressure and uterine blood flow. There were no changes in the measured fetal indices during maternal drug administration. Infusion of Saralasin to the fetus caused variable reductions in mean fetal arterial blood pressure and umbilical flow. There were no changes in maternal parameters measured. Therefore, in pregnant sheep in the third trimester, a component of normal uterine blood flow is maintained by endogenous AII, primarily through maintenance of adequate perfusion pressure.

Angiotensin II↗
PubMed1979

Radioangiographic measurement of the internal diameters of the uteroplacental arteries in rhesus monkeys.

The internal diameters of successive anatomic segments of the uteroplacental arteries in Macaca mulatta were measured at 100 to 150 dyas' gestation. Although the absolute values vary widely, the proportional relationships between segments are uniform from animal to animal and from one time in gestation to another. We also observed that each of the two uterine arteries supplies a restricted portion of the placenta with little overlap, that there is predominance of one uterine artery over the other in the number of placental lobes supplied, and that two radial arteries occasionally contribute to a single spiral artery, giving rise to an anastomotic loop.

Angiography↗
PubMed1979

Maternal-fetal transfer of melatonin in the non-human primate.

Melatonin was detected in the circulation of the near-term rhesus monkey (Macaca mulatta) and baboon (Papio papio) fetus. We determined whether the source could be the mother by studying placental transfer of melatonin in the rhesus monkey. When [3H]melatonin was administered i.v. to the mother it promptly appeared in the fetal circulation; the rates of disappearance of [3H]melatonin in the maternal and fetal circulations were parallel. The rapid decrease in circulating [3H]melatonin was associated with a rapid accumulation of [3H]melatonin-metabolites in the maternal and fetal circulations. Although the pattern of appearance of metabolites was similar in both circulations, relatively less [3H]melatonin-metabolites appeared in the fetal circulation. Acute changes in total maternal plasma melatonin, experimentally produced by giving a 20 min infusion of melatonin, were rapidly reflected in the fetus. This suggests that a daily rhythm in maternal melatonin would generate a similar rhythm in the fetus. The fetal monkey pineal was found to have the two enzymes necessary for the conversion of serotonin to melatonin. It is, however, not known whether fetal melatonin synthesis is rhythmic or the extent to which it could contribute to circulating melatonin levels at this or earlier stages of gestation.

Acetylserotonin O-Methyltransferase↗
PubMed1978

Effects of indomethacin on sheep uteroplacental circulations and sensitivity to angiotensin II.

Indomethacin, a prostaglandin synthetase inhibitor, injected simultaneously into the abdominal aorta of the ewe and her fetus at 125 days' gestation causes vasoconstriction of both the uterine and umbilical circulations. There is no change in these hemodynamic effects of indomethacin in the presence of phenoxybenzamine, an alpha-adrenergic antagonist. When the indomethacin experiment is repeated seven to 10 days later, a uterine vasoconstriction 10 per cent greater than that found earlier occurs, but there is no change from control umbilical vascular resistance. The mean maternal arterial pressure response (20 mm. Hg) to angiotensin II with and without indomethacin also was examined at the same time in gestation. Indomethacin infusion to the ewe significantly reduces the pressor dose (nanograms per kilogram per minute) by 42 +/- 4 per cent. Thus, in pregnant sheep in the third trimester, endogenous prostaglandins appear to be: (1) partial determinants of basal blood flow in both the uterine and umbilical circulations and (2) modulators of the vasoconstrictive effects of angiotensin II in the ewe.

Angiotensin II↗
PubMed1978

Vasoconstrictive effects of prostaglandins in sheep placental circulations.

Changes in the uterine and umbilical circulations after intra-aortic injection of prostaglandin E2 (PGE2) or protaglandin F2alpha (PGF2alpha) to either the fetus or the mother have been examined in 13 ewes at late gestation. PGF2alpha vien to either the fetus or the mother is vasoconstrictive in both uterine and umbilical circulations. PGE2 given to the fetus results in a dissociated response with vasodilation of the uterine circulation and vasoconstriction of the umbilical circulation. PGE2 given to the mother causes a uterine contraction that precludes specific hemodynamic analysis. Therefore, exposure of either maternal or fetal ovine circulation to exogenous prostaglandins in associated with acute changes in both placental circulations. Similar responses to pertubations in endogenous prostaglandin levels may exist in pregnant sheep.

Animals↗
PubMed1978

Contribution of dehydroepiandrosterone and its sulfate to estradiol in baboon pregnancy.

The metabolic clearance rates (MCR), conversion ratios (C), interconversion (rho), production rates (PR), secretion rates (SR), and relative contributions of maternal dehydroepiandrosterone (D) and D-sulfate (DS) to serum estradiol (E2) were determined in five pregnant baboons (Papio papio; 154-167 days gestation, term = 184 days) by constant intravenous infusion of [3H]DS and [14C]D. MCR-D (mean +/- SE) was greater (39.2 +/- 3.3 1/day.kg, P less than 0.001) than MCR-DS (3.1 +/- 0.3 1/day.kg). Because C-D leads to DS (5.460 +/- 0.461) exceeded (P less than 0.001) C-DS leads to (0.006 +/- 0.001), rho-DS leads to DS was greater (42.5% +/- 3.0%, P less than 0.001) than rho-DS leads to D (7.8 +/- 1.0%). C-D leads to E2 was greater (0.256 +/- 0.040) than C-DS leads to E2 (0.002 +/- 0.000). Using these values and serum levels of D (2.46 microgram/100 ml) and DS (18.9 microgram/100 ml) reported previously, SR and PR of D and DS were calculated. Of the total D produced (11.5 microgram/min), 98% was secreted, whereas only 32% of DS produced (7.1 microgram/min) was due to secretion. Using the serum D and DS levels and their conversion to E2, it was calculated that 89.7% of serum E2 was formed directly from D, 4.4% from D via DS, 1.8% from DS directly, and 4.1% from DS via D. It is concluded that, in spite of the low serum D level resulting from a high MCR, the large SR-D and more efficient conversion of D to E2 makes D, and not DS, the major circulating estrogen precursor in late baboon pregnancy.

Animals↗
PubMed1978

Lung lecithin synthesis in primates as related to respiratory distress syndrome.

Lecithin is synthesized de novo in the lung by two biochemical pathways, choline incorporation and phosphatidylethanolamine methylation. These studies in the Macaca mulatta fetus and neonate have demonstrated the relative contributions of the two pathways and the timing in monkey gestation of increased pulmonary lecithin production.

Amniotic Fluid↗