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Biomedical subjects

G Levinson

Publications and source records attributed to G Levinson.

At least 55 records · Page 3Linked to original sources
PubMed1979

Uterine blood flow and plasma norepinephrine changes during maternal stress in the pregnant ewe.

Because maternal stress may adversely affect the fetus, the authors tested the effects of brief episodes (15-60 sec) of maternal stress in 18 awake pregnant ewes. Maternal agitation and stuggling occurred either following non-painful stimuli such as loud noises or sudden movements of personnel (ten animals) or following the brief application of the ewe's skin of a uniform electrical stimulus of 30 volts with a frequency of 167 Hz for 30-60 sec (eight animals). Stimulation of either type produced a 45-50 per cent increase in mean maternal arterial blood pressure and a concomitant 32-52 per cent decrease in uterine blood flow (P less than 0.05). The decreases in uterine blood flow were brief, lasting less than 3 min, and were not associated with fetal asphyxia. Maternal plasma norepinephrine levels were measured following electrically induced maternal stress and were increased 25 per cent. The authors conclude that maternal stress may decrease uterine blood flow secondary to release of endogenous norepinephrine.

Acid-Base Equilibrium↗
PubMed1979

Dopamine treatment of spinal hypotension decreases uterine blood flow in the pregnant ewe.

In seven pregnant ewes, 3--5 min of hypotension resulting from spinal anesthesia decreased uterine blood flow 17 per cent. Dopamine, in doses sufficient to maintain blood pressure at control values (20--40 micrgram/kg/min) for 3--5 min, further decreased uterine blood flow to 56 per cent less than control and increased uterine vascular resistance to 50 per cent more than control. Following 30 min of hypotension, 30 min of dopamine administration in doses sufficient to restore blood pressure to control values (5--20 microgram/kg/min) similarly decreased uterine blood flow to 29 per cent less than control and increased uterine vascular resistance to 35 per cent more than control.

Anesthesia, Spinal↗
PubMed1978

Anaesthetic considerations in caesarean section for quadruplets.

A case of a caesarean delivery with epidural analgesia of a term parturient with quadruplets is presented. Maternal considerations of hypotension, respiratory embarrassment and aspiration of gastric content and foetal considerations of prematurity and impaired placental function are discussed relative to the use of general anaesthesia or epidural analgesia.

Adult↗
PubMed1978

Placental transfer of lidocaine: effects of fetal acidosis.

To investigate whether fetal acidosis increases the placental transfer of lidocaine, resulting in higher fetal blood levels of the drug, lidocaine was infused intravenously into ten pregnant ewes to maintain plasma levels of 2-4 microgram/ml. After maternal-fetal equilibrium was reached, the fetus was made acidotic by infusing lactic acid intravenously. Fetal blood pH decreased from 7.35 to 7.10. With fetal acidemia, fetal blood lidocaine levels increased significantly from 1.60 +/- 0.11 microgram/ml to 2.72 +/- 0.26 microgram/ml. The fetal-maternal lidocaine ratio increased from 0.76 to 1.21. Correction of the acidosis by bicarbonate infusion returned the fetal-maternal ratios to control values. It is concluded that acidosis in the fetus may result in trapping of ionized lidocaine in the fetal circulation and increase the transfer of lidocaine across the placenta.

Acidosis↗
PubMed1978

Dopamine administration in the normotensive pregnant ewe.

Dopamine was administered to pregnant ewes at randomly selected rates of 1, 3, 5, 10, 20, 30, or 40 microgram/kg/min. Doses less than 10 microgram/kg/min produced no significant change in maternal areterial blood pressure, cardiac output, or renal or uterine blood flow. Higher doses increased maternal cardiac output and blood pressure, did not change renal blood flow, but decreased uterine blood flow. Dopamine consistently caused mild maternal and fetal respiratory acidosis.

Animals↗
PubMed1977

The direct effects of circulating lidocaine on uterine blood flow and foetal well-being in the pregnant ewe.

We infused lidocaine intravenously into 13 pregnant ewes at a rate sufficient to maintain plasma levels between 2-4 mugm/ml, which are those commonly seen with regional anaesthesia. These levels did not change maternal blood pressure, pulse rate, cardiac output, stroke volume, total peripheral resistance, uterine blood flow or intra-amniotic pressure. Foetal blood pressure and pulse rate remained stable as did both maternal and foetal blood gases and acid-base values.

Animals↗
PubMed1977

Comparison of nitroprusside and hydralazine in hypertensive pregnant ewes.

During phenylephrine-induced hypertension in 6 near-term pregnant ewes, nitroprusside rapidly lowered the blood pressure to control values with no accompanying change in uterine blood flow. Hydralazine slowly lowered the blood pressure to control values. This change was accompanied by a statistically significant (15%) increase in uterine blood flow. Hydralazine also had a more pronounced effect than nitroprusside on cardiac output, heart rate, and total peripheral resistance. There were no significant acid-base changes in mother or fetus throughout the study.

Animals↗
PubMed1976

Further observations on postpartum ovarian refractoriness: effect of gonadal stimulation in women receiving bromocryptine.

It has been reported previously that the administration of human menopausal gonadotrophins (HMG) to lactating and non-lactating women from day 5 to day 9 postpartum elicited no significant elevation of urinary oestrogens or serum oestradiol within 15 days after delivery. In order to study further the role of prolactin on this ovarian refractoriness, five women receiving 7-5 mg of bromocryptine (CB-154) daily were given HMG at a dose of 300 iu per day, from day 5 to day 10 post-delivery. In all women serum oestradiol and urinary oestrogens showed no significant elevation within the 2 weeks after delivery. Serum prolactin was elevated in all cases and fell to normal nonpregnant levels immediately after CB-154 was administered. The suggestion that prolactin may possess antigonadotrophic activity at the ovarian level is not supported by the data presented here. The deficient ovarian response to gonadotrophin stimulation could be due to either the intraovarian effect of the high amounts of circulating steroids produced during gestation or to some unknown mechanism.

Bromocriptine↗
PubMed1976

An XX female with sexual infantilism, absent gonads, and lack of Müllerian ducts.

A patient with a 46,XX chromosome constitution showed the following main characteristics: lack of secondary sexual development, female external genitalia with absence of vagina, no gonadal structures, and complete lack of internal genitalia. This is a variant of the gonadal agenesis syndrome so far only described in association with and XY chromosome component. Endrocinology demonstrated that in the absence of gonadal feedback the pituitary responsiveness to synthetic luteinizing hormone-releasing hormone was increased.

Adolescent↗