PubMed Health⌕ Search

Biomedical subjects

C B Martin

Publications and source records attributed to C B Martin.

At least 91 records · Page 5Linked to original sources
PubMed1978

Antepartum evaluation of the pre-ejection period of the fetal cardiac cycle.

The pre-ejection period (PEP) of the cardiac cycle was studied in 65 antepartum fetuses by means of a noninvasive technique which used simultaneous recordings of abdominal fetal electrocardiogram (FECG) and ultrasound fetal Doppler cardiogram (FDCG). Although most of the fetuses were products of high-risk pregnancies, 45 fetuses had uneventful perinatal courses. The PEP's from these fetuses demonstrated a significant positive relationship with gestational age (p is less than 0.01). Uterine contractions induced for antepartum stress testing of the fetus were founnd to prolong the PEP by approximately 9.1 per cent in five cases (four fetuses). The average PEP of antepartum fetuses between 38 and 40 weeks was shorter than that of intrapartum fetuses by approximately 9.5 per cent. Comparison between clinical outcome and the PEP's of the fetuses who were born within a week after the last determination of PEP revealed a strong correlation between prolonged PEP duration and abnormalities in the perinatal course.

Electrocardiography↗
PubMed1978

Cardiac systolic time intervals in fetal monkeys: pre-ejection period.

The systolic time intervals of the fetal cardiac cycle were studied by means of simultaneous recordings of electrocardiogram (ECG) and ultrasound Doppler cardiogram (DCG) in chronic preparations of fetal rhesus monkeys. Recordings were made under physiologic conditions as well as during various experimental stresses. The pre-ejection period (PEP) showed no significant relationship with heart rate in the unstressed fetuses, but the acceleration of heart rate induced by epinephrine was accompanied by shortening of PEP. The PEP increased with advancing fetal age. The PEP was inversely correlated with left ventricular end-diastolic pressure and arterial pulse pressure, but showed a positive correlation with both systolic and diastolic arterial blood pressure. The PEP also exhibited strong negative correlation with arterial blood pH. the prolongation was essentially the same whether acidosis was of respiratory or metabolic origin. The PEP increased slightly but significantly during nonacidemic hypoxemia; however, there was no correlation between Pao2 and PEP Epinephrine shortened the PEP significantly, whereas the effect of atropine was inconsistent. Alteration of the plasma glucose level by injection of insulin or glucose did not affect PEP. These findings demonstrate that the PEP may be a useful indicator of fetal cardiac performance, reflecting both myocardial contractility and the hemodynamic state of the cardiovascular system.

Acidosis↗
PubMed1976

Umbilical cord compression associated with amniotomy: laboratory observations.

Impairment of umbilical cord blood flow has been associated with periodic fetal heart rate changes termed "variable decelerations." These patterns may be observed after amniotomy. A chronic fetal rhesus monkey preparation has been used to investigate this clinical observation. Loss of amniotic fluid produced variable deceleration patterns, while restoration of amniotic fluid volume eliminated such changes. These experimental data demonstrate that amniotic fluid may be critical in protection of the cord and maintenance of normal umbilical cord blood flow.

Amniotic Fluid↗
PubMed1976

Effect of thyrotropin-releasing hormone on secretion of thyrotropin, prolactin, thyroxine, and triiodothyronine in pregnant and fetal rhesus monkeys.

The effect of thyrotropin-releasing hormone (TRH) on the pituitary-thyroid axis and on prolactin secretion was studied in pregnant Rhesus monkeys during the latter period of gestation and in non-pregnant female controls. The baseline plasma concentrations of TSH, T3, T4, and prolactin (PRL) of pregnant monkeys did not differ from those of non-pregnant monkeys. After administration of TRH, plasma prolactin rose to higher levels in pregnant monkeys than in non-pregnant monkeys whereas there was a similar response of plasma TSH, T4 and T3 in both groups. The baseline plasma TSH was elevated and plasma T3 was decreased in the fetus compared with the mother. Administration of TRH iv to the maternal monkey caused a larger response in the fetal plasma TSH than in that of the mother and was followed by larger increments in plasma T4 and T3 concentrations in the fetuses than in the mothers. The larger increments of plasma TSH and thyroid hormones in the fetus compared with the mother also occurred when TRH was given iv to the fetus. There was a significant rise of plasma prolactin in both mother and fetus after administration of TRH to mother or fetus; the increase of plasma PRL was much higher in the mother than in the fetus. The data show that TRH can cross the primate placenta in either the maternal to fetal or fetal to maternal direction. The fetal thyroid of the Rhesus monkey during the latter period of gestation can release both T4 and T3 in response to TSH.

Amniotic Fluid↗
PubMed1975

Pharmacologic control of uterine contractility. In vitro human and in vivo monkey studies.

The exact cause and mechanism of the onset of labor are unknown but the theories are many. There is considerable evidence that prostaglandins are potent stimulants of uterine activity and may play a role in the onset of labor. Prostaglandin release may be the natural mediator of uterine contractions during labor. A group of anti-inflammatory compounds (aspirin-like compounds) that inhibit prostaglandin synthesis include indomethacin and fenoprofen. Inhibition of prostaglandin production is a reasonable approach to inhibiting premature labor. An excised muscle strip technique was used as a screening procedure for pharmacologic depression of human uterine activity in vitro, testing isoxsuprine, mesuprine, Alupent, ritodrine, indomethacin, and fenoprofen. The prostaglandin antagonists indomethacin and fenoprofen exhibited marked depressant activity. These drugs were further tested in an in vivo rhesus monkey preparation measuring uterine activity, maternal blood pressure, uterine blood flow, fetal heart rate, fetal blood pressure, and blood gases. Fenoprofen is effective in reducing uterine contractility without serious maternal or fetal side effects and shows promise as a clinically effective agent for pharmacologic control of premature labor.

Adrenergic beta-Agonists↗
PubMed1975

Significance of meconium during labor.

Continuous fetal heart rate (FHR) monitoring and routine fetal scalp blood sampling was utilized in the evaluations of 366 fetuses during labor. One hundred and six patients had meconium in the amniotic fluid at some time during labor. A total of 26,110 uterine contractions were monitored during these 366 labors. The incidence of FHR patterns as a percentage of uterine contractions was calculated for the meconium and nonmeconium groups. Although there was a 3 1/2-fold increase in the incidence of low five-minute Apgar scores (less than 7) in the meconium group, signs of fetal distress were, with rare esception, not significantly different from those in the nonmeconium group. The presence of meconium in the amniotic fluid without signs of fetal asphyxia (late decelerations and acidosis) is not a sign of fetal distress and need not be an indication for active intervention. The combination of fetal asphyxia and meconium staining of the amniotic fluid, however, does enhance the potential for meconium aspiration and a poor neonatal outcome. Universal fetal heart rate monitoring and appropriate fetal acid-base evaluation is recommended for following patients with meconium in the amniotic fluid during labor.

Acid-Base Equilibrium↗
PubMed1975

Effect of papain injection on mineral concentration in tissues of roosters and hens.

A study was made of the effect of injected papain on the concentration of calcium, iron, copper, zinc and selenium in tissues of roosters and laying hens. Half the males and females were injected intravenously with a papain solution and the other half with 0.9% sodium chloride. The roosters and half the laying hens were injected one-hour ante-mortem and the others injected 24 hours ante-mortem. The laying hens had less Zn, Fe, Cu and Ca in the skeletal muscle than the roosters, and less Fe and Cu, but equivalent amounts of Ca and Zn, in the kidneys. In the roosters the kidney contained approximately five times as much Se as the muscle. The liver contained equivalent concentrations of Se in the roosters and laying hens. Papain had no effect on the concentration of any of the elements in the tissues. There was no significant difference in the concentration of the minerals between one-hour and 24-hour ante-mortem injections of the papain in the laying hens.

Animals↗