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Biomedical subjects

R B Heap

Publications and source records attributed to R B Heap.

At least 127 records · Page 7Linked to original sources
PubMed1976

Production, chemical composition and prostaglandin F-2alpha content of uterine fluid in pregnant sheep.

A uterine pouch was prepared surgically in ewes before mating to study the production and chemical composition of uterine secretions during pregnancy. Pregnancy was established in 6 sheep and in the first 55 days uterine fluid was present in small amounts (less than 5 ml), whereas between 109 days post coitum and 3 days post partum the volume ranged from 90 to 775 ml. The chemical composition of uterine fluid in pregnancy differed from that of plasma especially in respect of its high concentration of total calcium (up to 83.5 mM) and prostaglandin (PG) F-2a (up to 1500 ng/ml). Progesterone was implicated as an important endocrine factor since uterine fluid (188 ml) with a high concentration of total calcium (53-5 mM) and PGF-2a(235ng/ml) was recovered from a non-pregnant sheep treated with progesterone for 115 days.

Animals↗
PubMed1975

Prostaglandins in pyometrial fluid from the cow, bitch and ferret.

1 Pyometra is a disorder of the uterus usually associated with bacterial infection plus obstruction. 2 Large quantities of fluid often collect in the uterus during this condition. 3 Pyometrial fluid obtained from three species was found to contain prostaglandin F2alpha, usually in large quantities. 4 Prostaglandin E2 was present in smaller quantities in five of the six samples. 5 These findings are discussed in relation to the known occurrence of prostaglandins in inflammatory fluid, and to the problem of infertility.

Animals↗
PubMed1975

Oestrogen, progesterone and corticosteroid concentrations in peripheral plasma of sows during pregnancy, parturition, lactation and after weaning.

Steroid hormone concentrations in plasma have been measured in blood samples taken from conscious sows with ear vein catheters. In late pregnancy, the plasma progesterone concentration ranged from 6 to 12 ng/ml and it decreased in all animals before the onset of parturition. Total unconjugated oestrogens increased to high values of up to about 3 ng/ml in late pregnancy and then declined after the onset of parturition. Oestrone was the predominant unconjugated oestrogen measured. Plasma corticosteroid (mainly cortisol) concentration was about 33 ng/ml and showed no consistent change at the time of parturition. During lactational anoestrum the plasma concentration of progesterone and total unconjugated oestrogens was very low, while that of corticosteroids was 21 ng/ml. When the piglets were weaned at 26-31 days, sows came into oestrus 4-12 days later, and this was preceded, or accompanied by, an increase in plasma oestrogens. In the luteal phase, plasma progesterone concentrations rose to 20-35 ng/ml. A sow whose piglets were removed at birth, showed signs of oestrus (vulval enlargement and a lordosis response), but a lack of receptivity to the boar associated with no detectable changes in the plasma oestrogen concentration; however, ovulation probably occurred since plasma progesterone values increased in a manner comparable to that found after the formation of normal corpora lutea in other sows. After a second non-receptive cycle, the sow was mated and became pregnant at the third post-weaning oestrus. At parturition the concentration of progesterone and total unconjugated oestrogens was greater in placental venous plasma than in maternal jugular plasma, which indicates placental synthesis of these hormones. A greater concentration of plasma corticosteroids in foetal blood than in placental venous or maternal jugular plasma suggests foetal synthesis in late pregnancy.

Adrenal Cortex Hormones↗
PubMed1975

Metabolic clearance rate, production rate and mammary uptake of progesterone in the goat.

The dynamics of progesterone uptake and metabolism in the mammary gland of the goat have been measured and related to the metabolic clearance rate and production rate of the hormone determined by tracer kinetic techniques. The metabolic clearance rate of progesterone from blood was 3-13 plus or minus 0-35 (S.E.M.) 1/min in ten experiments on six goats; values tended to be slightly higher in pregnant than in non-pregnant goats. The production rate of progesterone at oestrus, and at day 3 of the normal cycle, was less than 0-01 mug/min. During the luteal phase of the oestrous cycle the production rate was 8-5 and 14-6 mug/min in 2 animals, and in the second half of pregnancy, 15-3 plus or minus 0-6 mug/min (5 animals). Progesterone was extracted from the circulation by the mammary gland of conscious goats with an efficiency of 49-4 plus or minus 11-3% in non-pregnant, and 51-7 plus or minus 11-5% in pregnant aniamals. The mean clearance rate of progesterone by the udder was 0-279 1/min, 8-8% of the metabolic clearance rate. Mammary uptake of progesterone in goats with an actively secreting corpus luteum was 0-64 plus or minus 0-29 mug/min, which gave an estimated value of 0-11-1-88 ng/min/g mammary gland. The mammary extraction of progesterone was investigated in a goat 3 days after oestrus when any high affinity receptor sites would presumably be unoccupied. During the infusion of progesterone into a mammary artery, tissue sample were taken from various organs, including the mammary gland, and the concentration of labelled compounds at steady state was determined. A high mammary extraction of progesterone was found to be determined. A high mammary extraction of progesterone was found to be attributable principally to progesterone metabolism. The metabolites of progesterone were removed from the gland in venous blood and were not stored to any appreciable extent in mammary tissue. Experiments in vitro confirmed the findings in vivo that mammary tissue metabolized labelled progesterone and also pregnenolone and androstenedione; metabolism of dehydroepiandrosterone, oestradiol-17 beta, oestrone and cortisol was relatively small. Confirmation of our previous finding that the mammary gland of the goat can synthesize progesterone from labelled pregnenolone infused into the gland in vivo, further implicated this organ as an active site of metabolism of certain steroids. The physiological role of steroid metabolism in the mammary gland is discussed.

Androstenedione↗
PubMed1975

Metabolic clearance rate, production rate, and mammary uptake and metabolism of progesterone in cows.

Tracer kinetic techniques have been used to measure the production rate, metabolic clearance rate and mammary uptake of progesterone in six experiments on two Jersey cowsmthe cows were surgically prepared so that the carotid artery, jugular vein and mammary vein concentrations of progesterone, and udder blood flow, could be determined in conscious animals without anaesthesia or stress. The mean production rate of progesterone was 173 +/- 23-3 (S.ET) mug/min, with values ranging from 80 to 276 mug/min in pregnancy. The metabolic clearance rate was 22-5 +/- 2-0 1/min, or 0-21 +/- 0-025 1/min/kg metabolic body weight. The mammary uptake of progesterone was low, 3-1 +/- mug/min, and udder uptake accounted for about 3% of progesterone production rate. During [3H]A1progesterone infusion, radioactivity was transferred from blood to milk, probably by diffusion down a concentration gradient. Progesterone accounted for more than 88% of the ether-soluble radioactivity recovered from milk.

Animals↗
PubMed1975

The ultrastructure of the sheep placenta around the time of parturition.

Placental tissue, taken from seven sheep before, during and after delivery, was fixed and sectioned for study by transmission electron microscopy. Daily blood samples from the same sheep were taken from about 135 days p.c. and were analysed by radioimmunoassay for total unconjugated oestrogens. Sections of placentomal and interplacentomal areas were examined for ultrastructural variations that might be correlated with the endocrine changes observed over this period, and to determine whether placental separation preceded delivery of the fetus and whether separation occurred at the fetal-maternal junction or elsewhere. Ultrastructural correlates of the endocrine pattern were not detected. Placental separation occurred after delivery and involved disruption of the fetal tissue (trophoblast), while its microvillous attachment to the maternal symplasma remained intact.

Animals↗
PubMed1974

Studies on the metabolism of 5alpha-androst-16-en-3-one in boar tests in vivo.

1. [5alpha-(3)H]5alpha-Androst-16-en-3-one (5alpha-androstenone) was infused at a constant rate for 180min into the spermatic artery of a sexually mature boar. Samples of spermatic-venous blood were collected at 1min intervals for the first 10min of the infusion and thereafter at 15min intervals for the first hour, then at 64, 125, 155 and 172min. After infusion, the testis was removed and immediately cooled to -196 degrees C. 2. From both the testicular tissue and the spermatic-venous plasma, endogenous and (3)H-labelled androst-16-enes were isolated, characterized and quantitatively determined and their specific radioactivity was calculated. 3. The specific radioactivities of 5alpha-androstenore, 5alpha-androst-16-en-3alpha-ol and 5alpha-androst-16-en-3beta-ol (an-alpha and an-beta) in testicular tissue were different from those in the spermatic-venous plasma, suggesting that these compounds may be present in more than one compartment of the testis and differentially secreted into the spermatic-venous blood. 4. The ratios of the specific radioactivities of an-alpha and an-beta to their respective sulphate conjugates in the testicular tissue were less than the ratios of the same compounds in the spermatic-venous plasma. 5. The patterns of secretion of these labelled compounds in the spermatic-venous blood during the period of infusion were demonstrated. 6. The urine that accumulated during the infusion was analysed and found to contain (3)H-labelled an-beta, conjugated as both glucuronide and sulphate, the specific radioactivities of which were determined. Little or no androst-16-enes occurred as free steroids. 7. The presence of an-beta glucuronide in the urine is discussed.

Androstenes↗