Biomedical subjects

C A Jansen

Publications and source records attributed to C A Jansen.

8 recordsLinked to original sources

PubMed1979

Continuous variability of fetal PO2 in the chronically catheterized fetal sheep.

A method of continuous monitoring of fetal intravascular PO2 at various sites in the circulation in the chronically catheterized fetal sheep for up to 41 days (mean 11.1 days) has been compared with values obtained in blood samples measured extracorporeally in a standard blood gas analyzer. A double-blind comparison of the two methods showed that there was no bias between the two methods and correlation was 0.94. The stability of the electrodes was superior to that of a conventional blood gas analyzer. In every animal there was continuous variability of fetal vascular PO2. In the period from 105 to 126 days' gestation we noted the presence of slow increases in basal uterine tone that we have called "contractures". The frequency of these contractures was very regular at approximately one per hour. The frequency of these contracutres was very regular at approximately one per hour. There is a statistically significant related fall in fetal vascular PO2 in relation to these contractures. Well-coordinated uterine contractions during labor also produced a fall in fetal vascular PO2 that was related to the uterine activity.

Animals↗

PubMed1979

The effect of prostaglandin E2 infusion in the fetal lamb on fetal plasma ACTH, prolactin and cortisol concentrations.

PGE2 (2 micrograms/min) has been infused for 1h into the fetal jugular vein of 8 chronically catheterized fetuses on 13 occasions from 112 to 138 days gestation. Infusion of ethanol vehicle alone was conducted in fetuses from 111-139 days gestation. PGE2 administration produced a significant increase in fetal plasma cortisol after 30 min. No significant change was observed in fetal plasma prolactin concentration. Fetal plasma ACTH concentration was significantly elevated above resting concentration after 30 min. of PGE2 infusion. Metabolic clearance rate of PGE2 was 860 ml/min or 350 ml/kg/min. Intrauterine pressure was not changes during the infusion at any gestational age.

Adrenocorticotropic Hormone↗

PubMed1979

Ultrastructural changes in the placenta of the ewe after long-term intravascular infusion of 2-bromo-alpha-ergocryptine (CB154) into mother or fetus.

The fine structural appearance of the placenta of the ewe has been examined following long-term infusion of CB154 into either the fetus or the pregnant ewe. Binucleate cells which usually contain aggregations of spherical membrane-bound electron-dense inclusions, are a characteristic component of the chorionic epithelium of the sheep. Following CB154 infusion into either the fetus or ewe at 111 to 137 days of gestation, binucleate cells were partially or completely depleted of the droplets which are present in binucleate cells of control animals at a similar gestational age. No obvious changes in the maternal epithelial syncytium were observed after CB154 administration. Infusion of CB154 into the fetus alone was also followed by degenerative changes in some binucleate cells which ranged from condensation of nuclei to complete cell fragmentation. Either a direct or an indirect action of CB154 on binucleate cells is suggested by these observations. Hypoprolactinaemia followed CB154 infusion in all treated animals; its possible influence on binucleate cell activity is discussed.

Animals↗

PubMed1979