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Biomedical subjects

K Adamsons

Publications and source records attributed to K Adamsons.

At least 37 records · Page 2Linked to original sources
PubMed1978

Contribution of maternal circulation to blood-borne progesterone in the fetus. II. Studies on sheep.

Catheters were placed in maternal and fetal vessels in four ewes in the last month of gestation. Tritiated progesterone (P) was infused at a constant rate into a maternal peripheral vein. Specific activities and endogenous concentrations of P were measured in blood samples drawn from a maternal artery and either a fetal femoral artery or an umbilical vein. Comparison of the specific activities of P in fetal and maternal samples revealed that direct secretion of the placental hormone into the umbilical vein accounted for 90 to 93 per cent of the hormone in the fetal circulation. Estimates of the rates of production of P in the fetal circulation, obtained by multiplying metabolic clearance rates previously reported and concentrations of P in a fetal femoral artery, indicate that placental P is preferentially secreted toward the maternal circulation.

Animals↗
PubMed1978

The effects of isoproterenol on fetal oxygenation.

Infusion of isoproterenol (1 microgram/kg/min, i.v.) into the anesthetized pregnant rhesus monkey near term consistently reduced fetal oxygenation, despite diminishing myometrial activity. The decline in pO2 of fetal arterial blood (mean = 4.3 +/- 2.3 mmHg S.D.) was accompanied by an increase in pCO2 tension (mean = 4.6 +/- 2.7 mmHg) and a decline in pH (mean = 0.04 +/- 0.02 S.D.). There was an increase in heart rate and a widening of pulse pressure in the mother and also in the adequately oxygenated fetus providing evidence that the agent crosses the placenta. The poorly oxygenated fetuses developed bradycardia and hypotension. Administration of isoproterenol directly to the fetus elicited similar changes in the composition of blood, and in blood pressure and heart rate, to those observed after administration of the agent to the mother.

Animals↗
PubMed1977

Late decelerations and brain tolerance of the fetal monkey to intrapartum asphyxia.

Eight monkey fetuses near term were subjected to regulated asphyxia during labor by mechanically constricting the maternal abdominal aorta and diminishing blood flow to the uterus. A magnitude of asphyxia was produced and maintained for an initial three hours that was close to but not sufficient to elicit late decelerations. The asphyxia was then augmented during a fourth hour to cause late decelerations of magnitudes of 5 to 15 per cent of the initial heart rate. After termination of the fourth hour of asphyxia, the fetuses were delivered by hysterotomy and provided intensive care. During the three to nine months of survival after birth, all animals were neurologically intact; on necropsy the brains were free of pathologic changes both grossly and microscopically. These results support the thesis that fetal heart rate monitoring during labor exhibits a sensitivity sufficient to diagnose asphyxia of the fetus of clinical significance before it reaches a magnitude that may cause permanent neurological injury. The results are particularly pertinent to those clinical circumstances where the decreases in intervillous space blood flow brought about by uterine contractions are accentuated due to low maternal blood pressure.

Animals↗
PubMed1976

Narcotic dependency in pregnancy. Methadone maintenance compared to use of street drugs.

The course of pregnancy and delivery in 28 women under closely supervised methadone maintenance (group 1) was compared with that of 57 women using heroin or methadone under less controlled circumstances (group 2) and with that of 30 women free of mood-altering medications (group 3). Women in group 1 had the lowest incidence of coexisting medical problems (p=.025), with an incidence of fetal distress not statistically different from that of women in group 3. Infants born to women group 2 had the highest fetal distress (p less than.05), with four congenital defects, one stillbirth, and one neonatal death. Symptoms characteristic of narcotic withdrawal occurred with similar frequency in group 1 and 2 infants, appearing earlier in children whose mothers were users of heroin. These findings indicate that maintenance of the pregnant addict under closely supervised methadone therapy is compatible with an uneventful pregnancy and birth of a healthy infant whose withdrawal symptoms in the neonatal period are readily controllable.

Adolescent↗
PubMed1975

Response of the primate fetus to intra-amniotic saline injection.

The amniotic fluid was replaced with 20 per cent sodium chloride solution during the second half of gestation in 12 pregnant rhesus monkeys. This produced a congealing of the fetal blood in the small umbilical vessels which overlie in the placental chorionic plate. Death of severe asphyxia followed within 20 to 50 minutes in the younger fetuses due to a prompt cessation of umbilical blood flow. During this time, the rise in serum sodium of the fetus was moderate and could not be implicated as the cause of fetal death. In older fetuses, the asphyxia produced by the saline injection was transient and less severe, occasionally permitting survival. The caliber of the affected fetal umbilical blood vessels and their blood flow rates are presented as the principal determinants of the rapidity of development and the severity of the asphyxia produced by saline instillation.

Abortion, Induced↗