bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE REGULATION OF INSULIN SECRETION BY THE OVINE FOETUS IN UTERO
Authors: BASSETT J. M. , THORBURN G. D. 
Published: December 2008

SUMMARY
Foetal lambs (100–150 days' gestation) with indwelling vascular catheters were used to study the regulation of the insulin concentration in the plasma of foetal lambs in utero. Immediately after the implantation of the catheters the insulin concentration in foetal plasma was significantly correlated with the foetal glucose and fructose concentrations and with the maternal glucose concentration. On the next day the foetal insulin concentration was significantly correlated only with the maternal glucose concentration.
Both glucose and fructose, when infused i.v., increased the insulin concentration in foetal plasma, but the increases were slow and far less than those observed in newborn lambs infused with glucose or fructose. Intravenous infusion of isoprenaline or glucagon did not alter the plasma insulin concentration of foetal lambs, but both caused a rapid increase in the insulin concentration of newborn lambs. Glucagon did not potentiate the insulin response to glucose. Addition of aminophylline to a glucagon infusion failed to cause insulin secretion in foetal lambs. The results suggest the cyclic-3′,5′-AMP dependent part of the insulin secretory mechanism does not develop fully before the last week of gestation.
Gel filtration of foetal plasma on Sephadex indicated that the immunoreactive material present was insulin. No significant amounts of proinsulin were found.
COMPARISON OF EFFECTS OF PROLONGED ALDOSTERONE ADMINISTRATION ON RAT COLON AND RENAL ELECTROLYTE EXCRETION
Authors: THOMPSON B. D. , EDMONDS C. J. 
Published: December 2008

SUMMARY
Rats were given a continuous intravenous infusion of aldosterone for up to 16 days. The rate of urinary Na+ excretion was initially depressed, but 'escape' occurred in about 4 days. Diurnal variation of Na+ excretion rate persisted even when the Na+ intake rate was controlled by infusion and when there was a continuous high level of exogenous aldosterone. After stopping aldosterone infusion, a transient rise in the rate of Na+ excretion was observed. Colonic transepithelial potential difference remained elevated as long as the infusion was continued and the short-circuit current, which is largely accounted for by active Na+ absorption, was increased. Stool Na+ content was reduced. The Na+ transport system of colonic epithelium, unlike that of kidney, does not appear to escape from the effect of aldosterone.
INDUCTION OF PSEUDOPREGNANCY IN RATS WITH MEDROXYPROGESTERONE
Authors: MANTALENAKIS S. J. 
Published: December 2008

SUMMARY
A daily dose of 1 mg medroxyprogesterone acetate (MAP) injected into rats for 2, 4 or 8 consecutive days, beginning on the day of oestrus, resulted in a high implantation rate of transferred 5-day blastocysts and a high survival of foetuses to term.
The best results were obtained with daily injections of 1 or 2·5 mg of MAP for 3 consecutive days, with blastocyst transfer on day 5 between 09.00 and 12.00 h. Such rats showed a decidual reaction characteristic of pregnancy. Extension of pseudopregnancy over 15 days by daily injections of 2·5 mg MAP resulted in a decrease in blastocyst implantation and a failure of foetal survival.
THE EFFECT OF CLOMIPHENE ON THE PLASMA ANDROGENS OF PREPUBERTAL AND PUBERTAL BOYS
Authors: CATHRO D. M. , SAEZ J. M. , BERTRAND J. 
Published: December 2008

SUMMARY
Plasma levels of testosterone, androst-4-ene-3,17-dione, dehydroepiandrosterone (DHA) and dehydroepiandrosterone sulphate (DHAS) were estimated both before and after administration of clomiphene citrate to endocrinologically normal boys aged from 2–16 yr and to boys with adrenocortical hypofunction or hypogonadism. A divided daily dose of 200 mg/1·7 m2 of surface area was maintained for 15 days. The unconjugated steroids were measured by means of a double isotope derivative technique and the sulphates by gas-liquid chromatography.
The boys without testicular anomaly who were well established in puberty responded with a rise in plasma testosterone. In contrast, prepubertal boys showed a statistically significant decrease in plasma testosterone levels.
A concomitant finding was a significant rise in the plasma levels of androstenedione, DHA and DHAS. It is concluded that clomiphene does not liberate luteinizing hormone before puberty but it may well diminish its secretion. A secondary effect of clomiphene is the stimulation of adrenal C19-steroid production.
THE ALDOSTERONE SECRETORY RESPONSE TO SODIUM RESTRICTION IN CHRONICALLY HYPOPHYSECTOMIZED CORTICOTROPHIN-MAINTAINED RATS AS A FUNCTION OF DURATION AND AMOUNT OF GROWTH HORMONE TREATMENT
Authors: PALKOVITS M. , de JONG W. , van der WAL B. , de WIED D. 
Published: December 2008

SUMMARY
Daily administration of growth hormone (STH) to hypophysectomized rats treated with adrenal maintenance doses of corticotrophin restored the aldosterone secretory response (as measured by the synthetic capacity of the adrenal in vitro) to sodium restriction. Treatment with STH for the first 2 days after hypophysectomy or on the 7th day after hypophysectomy failed, but treatment during the 6th and 7th day after hypophysectomy with 100, 200 or 400 μg STH/day restored the aldosterone secretory response to sodium deprivation in a dose-dependent manner.
THE EFFECTS OF CYPROTERONE ACETATE ON THE SPONTANEOUS ACTIVITY AND SEMINAL VESICLE WEIGHT OF MALE RATS
Authors: STERN J. J. , MURPHY M. 
Published: December 2008

SUMMARY
The wheel-running activity of 19 male rats was examined before and after castration. Castration significantly reduced spontaneous activity. Testosterone propionate (TP) administration increased activity to levels before castration. Cyproterone acetate given with TP did not inhibit the increase in activity but inhibited the growth of seminal vesicles.
EFFECT OF DECREASED DIETARY PROTEIN ON THE RATE OF THYROID HORMONE SECRETION AND FOOD CONSUMPTION IN RATS
Authors: SINGH D. V. , ANDERSON R. R. , TURNER C. W. 
Published: December 2008

SUMMARY
One hundred and twenty albino female rats (Sprague-Dawley-Rolfsmeyer) were divided into five equal groups. Rates of thyroxine secretion (TSR) and food consumption were determined during the control period, and 10 and 25 days after initiation of dietary treatment. Animals in each group served as their own controls for the following modifications of their diet: (1) protein-free diet, (2) 5% protein (casein) diet, (3) 10% protein diet, (4) 15% protein diet, and (5) 20% protein diet. Purina lab chow (23·4% protein) and the 20% casein diet served as control diets. The TSR, the body weight and amount of food consumed were depressed significantly in the group fed on a protein-free diet for 10 and 25 days. The group fed 5% protein diet had a non-significant decrease in TSR as compared with the controls. Similarly, TSR was not reduced by 10, 15 or 20% protein diets. Food consumption decreased significantly in the groups fed a 5, 10 and 15% protein diet, but not in the group on 20% casein. Body weight decreased significantly in the groups on a protein-free diet and on a 5% protein diet.
It would appear from these results that protein content of the diet does not become a limiting factor for TSR until it is lower than 5%. It is suggested that the calorie intake plays a more important role in regard to TSR than a low protein content of the food.
WATER AND ELECTROLYTE DISTRIBUTION IN RAT AND GUINEA-PIG THYROID GLANDS
Authors: CHOW S. Y. , WOODBURY D. M. 
Published: December 2008

SUMMARY
Procedures for the calculation of the volume of water and the Na+, K+ and Cl− concentrations in the three anatomical compartments of the thyroid (interstitium, follicular cells and lumen) are described. There was an excellent correlation between the volume of water of these three compartments calculated from the total water, [14C]inulin space and histometric measurements of the thyroid gland and the results obtained from 3H2O-uptake studies. Na+ and K+ concentrations in the luminal fluid of rat and guinea-pig thyroid glands were the same as those in the interstitial fluid which is an ultrafiltrate of plasma. Cl− concentration in the luminal fluid of thyroid gland was usually lower than that in the interstitial fluid. The concentration depends on the amount of colloid present in the follicular lumen. In the cellular fluid of the thyroid follicle, Na+ and Cl− concentrations were low and K+ concentration was high. The Cl− equilibrium potential between the interstitial and the cellular compartments, calculated from the corresponding Cl− concentrations by the Nernst equation, was the same as for previous values reported for the intracellular potentials determined by micro-electrode techniques in both rat and guinea-pig thyroid glands. In the rat thyroid, the calculated Cl− equilibrium potential between the interstitial and the luminal compartments was the same as the measured intra-luminal potential. However, in the guinea-pig thyroid the calculated Cl− equilibrium potential between the interstitial and the luminal fluids was considerably higher than the measured intra-luminal potential.
OBSERVATIONS ON THE PINEAL GLAND, THE HARDERIAN GLANDS, THE RETINA, AND THE REPRODUCTIVE ORGANS OF ADULT FEMALE RATS EXPOSED TO CONTINUOUS LIGHT
Authors: REITER R. J. , KLEIN D. C. 
Published: December 2008

SUMMARY
Harderian gland removal caused enlargement of the uteri of adult female albino rats which were maintained in 14 h light and 10 h darkness/day. Constant light exposure led to regression of the ovaries, adrenal glands and Harderian glands while the uteri exhibited a significant hypertrophic response. None of these changes were affected by surgical removal of the Harderian glands. The eyes and the retinas of albino rats maintained under continuous illumination underwent atrophic changes with the receptor cell elements of the retinas completely disappearing within 9½ weeks.
Constant light obliterated the diurnal rhythm in the pineal enzyme, N-acetyltransferase. Neither the activity of pineal hydroxyindole-O-methyl-transferase nor the activity of pineal N-acetyltransferase were influenced by removal of the Harderian glands.
THE COMPARATIVE ACTIONS OF TESTOSTERONE PROPIONATE AND 5α-ANDROSTAN17β-OL-3-ONE PROPIONATE ON THE REPRODUCTIVE BEHAVIOUR, PHYSIOLOGY AND MORPHOLOGY OF MALE RATS
Authors: FEDER H. H. 
Published: December 2008

SUMMARY
5α-Androstan-17β-ol-3-one in its free or in its propionate form was injected systemically (125 μg/day/rat) into sexually experienced, adult, castrated, male rats. These compounds were ineffective in activating masculine behaviour patterns, despite having measurable effects on body weight, seminal vesicle weight and penile morphology. The propionate form also had strong anti-gonadotrophic properties, since when it was injected for 6 days into intact, immature, male rats it significantly reduced testicular weight.
In contrast, testosterone propionate (125 μg/day/rat) restored male sexual behaviour to the levels found before castration when injected systemically. Testosterone propionate also affected body weight, seminal vesicle weight, penile morphology and the testicular weight of immature males. These effects may have been due in part to conversion of testosterone to 5α-androstan-17β-ol-3-one, but this metabolic step does not seem to be obligatory for activation of male sexual behaviour in rats.
HUMAN FOETAL PANCREATIC INSULIN SECRETION IN RESPONSE TO IONIC AND OTHER STIMULI
Authors: MILNER R. D. G. , BARSON A. J. , ASHWORTH M. A. 
Published: December 2008

SUMMARY
Pieces of human foetal pancreas were incubated under control conditions and in media containing different stimuli of insulin release. Insulin secretion was stimulated from the pancreases of foetuses (83–625 g body weight) which were of 16–24 weeks gestational age. Potassium (60 mmol/l), barium (2·54 mmol/l) and ouabain (10−5 mol/l) were effective stimuli in all experiments. Glucagon (5 μg/ml), theophylline (1 mmol/l) and dibutyryl 3′,5′-cyclic adenosine monophosphate (1 mmol/l) stimulated insulin secretion in media containing 0, 0·6 or 3·0 mg glucose/ml. Theophylline and dibutyryl 3′,5′-cyclic adenosine monophosphate were effective in all experients and glucagon stimulated insulin release in four out of six experiments. At all ages studied, histological examination of the pancreas after each experiment revealed islets of Langerhans containing β cells. In most cases the islets were of the mantle type but occasionally bipolar islets were seen. Cellular normality, as judged by light microscopy, was preserved after periods of incubation for up to 5½ h. Glycogen was demonstrable in the pancreatic acinar tissue but not in the islets.
The results of these experiments indicate that, between the 16th and 24th week of foetal life, the human β cell is capable of releasing insulin in vitro when stimulated appropriately.
PROBLEMS IN ELECTRICAL STIMULATION OF AFFERENT PATHWAYS FOR OXYTOCIN RELEASE
Authors: URBAN I. , MOSS R. L. , CROSS B. A. 
Published: December 2008

SUMMARY
Recent investigations in the rabbit have indicated the presence of well-defined afferent nervous pathways for release of neurohypophysial oxytocin. To study these pathways for later use in hypothalamic unit recording, intramammary pressure responses (milk ejection) and arterial pressure were recorded in 45 lactating rabbits with post-pontine brainstem transection. Systematic exploration of the mid-brain tegmentum and ventromedial forebrain areas was carried out with a bipolar stimulating electrode. Release of oxytocin, shown by milk-ejection responses similar to those evoked by a 1–2 mu. synthetic oxytocin occurring in the absence of detectable pressor effects, was recorded in less than half the animals. The location of positive stimulation sites was very variable between animals and reproducibility of responses from the same site was poor. It is concluded that present evidence does not support a discrete afferent path in the mid-brain for the milk-ejection reflex and a possible explanation for the inconstant results of stimulation experiments is suggested.
EFFECT OF PROGESTERONE ON SURVIVAL OF BLASTOCYSTS IN UTERI OF OVARIECTOMIZED MICE
Authors: WEITLAUF H. M. 
Published: December 2008

SUMMARY
Mice were ovariectomized on day 4 of pregnancy and injected daily with either progesterone or oil vehicle (day 1 = the day of vaginal plug). Blastocysts were recovered on day 10, 20 or 30, counted and transferred to ovariectomized recipients. Implantation was induced and pregnancy maintained by daily injections of oestradiol and progesterone. Viability of the blastocysts was assessed by determining the percentage that developed into normal foetuses. A similar number of eggs was recovered from both groups at each time-interval; thus progesterone did not influence the retention of blastocysts by ovariectomized mice. In contrast, progesterone did influence the viability of the embryos. The percentage of blastocysts developing normally from the oil-treated animals was: 39% on day 10, 19% on day 20 and less than 1% on day 30. Corresponding percentages for the progesterone-treated animals were: 40% on day 10, 35% on day 20 and 35% on day 30.
THE EFFECTS OF HYPERMAGNESAEMIA ON CALCITONIN SECRETION IN VIVO
Authors: CARE A. D. , BELL N. H. , BATES R. F. L. 
Published: December 2008

SUMMARY
The influence of magnesium on calcitonin (CT) secretion rate has been studied in pigs by perfusion of porcine thyroid glands, isolated in situ, under controlled conditions of flow rate and blood electrolyte composition. At concentrations of 4·4–12·7 mequiv./l, magnesium stimulated CT secretion in the presence of a normal calcium concentration in the perfusate. The maximum effect was reached at a concentration of about 7 mequiv. Mg/l. At higher magnesium concentrations, the secretion rate of CT tended to revert towards that found with concentrations of calcium and magnesium within the normal range. When hypermagnesaemia was superimposed on hypercalcaemia there was a fall in the secretion rate of CT as the Mg: Ca ratio in the perfusing blood plasma approached 1. The stimulatory effect of hypermagnesaemia was usually less than that caused by an equimolar increase in plasma calcium concentration. The results suggest that changes in plasma magnesium concentration probably do not influence CT secretion under normal conditions.
EFFECTS OF PROLACTIN, CORTICOTROPHIN AND CORTISOL ON THE ADENOHYPOPHYSIS AND INTERRENAL GLAND OF ANADROMOUS THREESPINE STICKLEBACKS, GASTEROSTEUS ACULEATUS L. FORM TRACHURUS, IN WINTER AND SUMMER
Authors: LEATHERLAND J. F. , LAM T. J. 
Published: December 2008

SUMMARY
In 'winter' anadromous threespine sticklebacks (Gasterosteus aculeatus L. form trachurus), corticotrophin (ACTH) injections significantly decreased the size of epsilon-cells (corticotrophs), alpha-acidophils (somatotrophs) (with an apparent increase in the degree of degranulation) and dorsal basophils (thyrotrophs) (with an apparent increase in granulation). Corticotrophin was also found to increase interrenal nuclear size, to decrease body length and to cause the development of a green skin coloration typical of summer fish. Cortisol injections significantly decreased the size of thyrotrophs and increased the size of periodic acid—Schiff's reagent (PAS)-negative cells of the pars intermedia. Prolactin injections significantly decreased the size of the thyrotrophs and caused the development of a green skin coloration though to a lesser extent than ACTH injections.
In 'summer' sticklebacks which received fewer injections than winter fish (four compared with ten) ACTH significantly decreased the size of corticotrophs and PAS-negative cells of the pars intermedia whereas cortisol produced no significant effect on any of the cells studied.
STIMULATION OF RABBIT OVARIES BY HUMAN CHORIONIC GONADOTROPHIN IN THE ABSENCE OF ENDOGENOUS GONADOTROPHINS
Authors: BETTERIDGE K. J. 
Published: December 2008

SUMMARY
The ovulatory response of hypophysectomized rabbits to 100 i.u. human chorionic gonadotrophin (HCG) i.v. declined progressively as the interval between pituitary removal and HCG injection was increased from 0 to 12 h. Hypophysectomized rabbits were also treated with HCG 2·5 h after receiving an ovary transplanted with vascular anastomoses from an oestrous donor. The proportion of grafts showing positive follicular responses to HCG in these recipients (2/4) was the same as in similarly treated intact recipients (1/2). It was concluded that endogenous gonadotrophins were not essential for HCG to stimulate follicular growth and ovulation. Therefore, the disappearance of gonadotrophins after hypophysectomy probably reduced the effect of HCG by inducing follicular regression and unresponsiveness rather than by removing synergistic hormones.
INHIBITION OF OVULATION BY AN ANTI-PIG-LUTEINIZING HORMONE SERUM
Authors: BETTERIDGE K. J. 
Published: December 2008

SUMMARY
In rabbits, an anti-pig-luteinizing hormone serum (anti-pig-LH) inhibited coitally-induced ovulation when injected immediately post coitum and this effect persisted for at least 5 days. When administered 90 min after mating, anti-pig-LH had very little inhibitory effect on ovulation and did not prevent the establishment of normal pregnancies. Anti-pig-LH also blocked human chorionic gonadotrophin-induced ovulation in rabbits, evidently by direct cross reaction. Sufficient anti-pig-LH to block ovulation in rabbits inhibited neither ovulation nor conception in four guinea-pigs when injected 0 to 4 days before vaginal opening.
EFFECTS OF HISTOLOGICAL AND ELECTRON MICROSCOPICAL FIXATIVES ON THE INSULIN CONTENT OF THE RAT PANCREAS
Authors: GRILLO T. A. I. , OGUNNAIKE P. O. , FAOYE S. 
Published: December 2008

SUMMARY
The effects of chemical fixatives such as the aldehydes, as well as ethanol, on the insulin content of the rat pancreas were studied. Although there was some loss of insulin after the use of all the fixatives investigated it was found that glutaraldehyde preserved the greatest amount of the hormone at both room and low temperature. Insulin was still preserved in the pancreas after glutaraldehyde fixation even after the complete preparation of the tissue for histology or electron microscopy. The insulin extracted from the pancreas after fixation in formaldehyde was still biologically active and it enhanced the formation of glycogen in the rat diaphragm.
THE DISTRIBUTION OF METABOLITES OF [7α-3H]PROGESTERONE IN TISSUES OF MICE
Authors: TAYLOR W. , WRIGHT D. E. 
Published: December 2008

SUMMARY
[7α-3H]Progesterone was administered to two groups of mice. The localization of radioactivity in tissues was examined by autoradiography and by liquid scintillation counting. Particular attention was paid to the distribution of radioactivity in the liver and biliary system. The greatest amount of administered steroid was taken up by the liver, rapidly secreted into the biliary system and excreted into the gastrointestinal tract. Other tissues, including the uterus, did not take up any appreciable amount of radioactivity, and the autoradiographs showed that radioactivity was not associated with any particular region of hepatic and other cells. The biological half-life of radioactivity in the blood was 11 min in animals given labelled progesterone intravenously.
CONVERSION OF [4-14C]PROGESTERONE TO ANDROSTERONE BY FEMALE RHESUS MONKEYS (MACACA MULATTA)
Authors: PLANT T. M. , JAMES V. H. T. , MICHAEL R. P. 
Published: December 2008

SUMMARY
Labelled progesterone was administered intravenously to five, adult female rhesus monkeys and urine and faeces were collected every 24 h. Excretion of radioactivity in urine occurred most rapidly in the first 24-h period and then declined exponentially. The excretion of radioactivity in faeces reached maxima during the 2nd, 3rd or 4th 24-h periods depending on the animal studied. 76–94% (mean 86%) of the radioactivity administered was recovered within 9 days, but small quantities continued to be excreted in urine up to 16 days after injection. Generally, greater amounts of radioactivity were recovered from faeces (41–57%) than from urine (26–48%). Using different hydrolytic and extraction procedures, some 50% of the radioactivity in urine was recovered in the neutral extracts. The major metabolite in urine was androsterone which accounted for 1·1–12·2% (mean 6·0%) of the progesterone administered. Pregnanediol was not an important urinary catabolite in this species. Differences in the extent to which progesterone is metabolized to C-19 compounds in macaques, baboons, great apes and man may reflect the phylogeny of a catabolic desmolase system in anthropoid primates.