bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE MAINTENANCE OF PREGNANCY, AND PARTURITION, IN GUINEA-PIGS HYPOPHYSECTOMIZED WITHIN 4 DAYS OF MATING
Authors: ILLINGWORTH DOREEN V. , PERRY J. S. , ACKLAND NICOLA , BURTON ANGELA M. 
Published: December 2008

SUMMARY
Pregnancy was sustained to term (>63 days) in 15 out of a total of 46 guinea-pigs, hypophysectomized within 4 days after mating. The majority (22/29) of complete or partial abortions occurred between 20 and 35 days post coitum. Analysis of plasma samples showed that the pregnant hypophysectomized animals with live foetuses had high progesterone and progesterone-binding protein concentrations, equivalent to those found in intact pregnant guinea-pigs. Animals that received daily injections of cortisone acetate from day 55 (7/15) gave birth to live young at the normal time (67–68 days). Plasma samples from one animal taken during parturition showed no measurable oxytocin in maternal plasma, but oxytocin was present in foetal plasma at the moment of birth.
THE RELATIONSHIP BETWEEN FOOD, GASTRO-INTESTINAL HORMONES AND CALCITONIN SECRETION
Authors: SWAMINATHAN R. , BATES R. F. L. , BLOOM S. R. , GANGULI P. C. , CARE A. D. 
Published: December 2008

SUMMARY
The role of calcitonin (CT) in postprandial calcium homeostasis and the possibility of a gastroentero-thyroid C-cell system was studied in young pigs. When pigs were fasted for more than 36 h and then fed, the plasma calcium concentration decreased by 6·1% over a period of 60–120 min after a meal. Since in thyroidectomized pigs the plasma calcium concentration increased by 7·2% when they were fed after a fast of 36 h it is suggested that increased CT secretion assists in the control of postprandial hypercalcaemia. Direct measurement of CT in peripheral plasma supported this suggestion. Because the plasma calcium concentration in an intact pig on a normal feeding regime does not change after a meal, the possibility of the involvement of one or more humoral factors in the stimulation of thyroid C-cells was investigated. Exogenous gastrin and endogenous gastrin stimulated by meat extract were both previously shown by us to increase CT secretion rate. This observation has now been extended to include other stimuli to endogenous gastrin, e.g. glycine and gastric distension. Furthermore, partially purified enteroglucagon increased CT secretion rate from perfused thyroid glands, isolated in situ. Stimulation of endogenous entero-glucagon by the intraduodenal administration of glucose, and probable stimulation of endogenous pancreozymin by intraduodenal fat, were both associated with an increased CT secretion rate from the thyroid gland.
These results support the concept of a gastroentero-thyroid C-cell system which serves to stimulate CT secretion and thus to protect the skeleton from excessive bone resorption during periods of dietary sufficiency.
RADIOIMMUNOASSAY OF PLASMA ADRENOCORTICOTROPHIN IN CUSHING'S SYNDROME
Authors: CROUGHS R. J. M. , TOPS C. F. , de JONG F. H. 
Published: December 2008

SUMMARY
The present study describes a radioimmunoassay for plasma adrenocorticotrophin (ACTH) in man with a sensitivity of at least 15 pg/ml. In-vitro studies using various fragments of ACTH showed immunobiological dissociation. However, this phenomenon does not appear to be of major importance in vivo, since stimulation and suppression tests showed overall parallel changes of immunoreactive plasma ACTH and plasma cortisol. The results obtained from patients with various forms of Cushing's syndrome are presented. It is concluded that basal plasma ACTH determinations are useful in the differential diagnosis of Cushing's syndrome and may help in predicting the development of a pituitary tumour after adrenalectomy.
The supranormal plasma cortisol response to i.m. injection of lysinevasopressin in subjects with pituitary-dependent Cushing's syndrome is attributed both to an increased ACTH release by the pituitary and to an excessive response of the hyperplastic adrenal cortex. The i.v. infusion of dexamethasone at a rate of 1 mg/h for 5 h in subjects with pituitarydependent Cushing's syndrome was followed by significant and parallel decreases of both immunoreactive plasma ACTH and plasma cortisol. No rise of plasma ACTH levels was found with insulin-induced hypoglycaemia in subjects with untreated pituitary-dependent Cushing's syndrome.
CIRCADIAN PERIODICITY OF PITUITARY-ADRENAL FUNCTION AFTER p-CHLOROPHENYLALANINE ADMINISTRATION IN THE RAT
Authors: van DELFT A. M. L. , KAPLANSKI J. , SMELIK P. G. 
Published: December 2008

SUMMARY
Two days after a single or repeated administration of p-chlorophenylalanine (p-CPA; 316 mg/kg i.p.) in the rat, a marked diminution to 20% of control levels of brain 5-hydroxytryptamine, partial but not complete abolition of the circadian pituitary—adrenal rhythm and a profound decrease in adrenal responsiveness to ether stress or exogenous adrenocorticotrophin were found. Pituitary—adrenal activity in unstressed or stimulated animals was assessed by the level of corticosterone in plasma and the corticosteroid production by adrenal tissue in vitro. The effect of p-CPA administration on changes in pituitary—adrenal periodicity were concomitant with a reduction in food intake and body growth and a pronounced increase in adrenal weight. In the light of the marked functional alterations after p-CPA treatment, the proposed relationship between decreased brain 5-hydroxytryptamine content and pituitary—adrenal periodicity is questioned.
ANDROGEN METABOLISM IN THE VENTRAL SEBACEOUS GLAND PATCH OF THE MONGOLIAN GERBIL
Authors: HODGINS M. B. , HAY J. B. 
Published: December 2008

SUMMARY
The metabolism of [7α-3H]dehydroepiandrosterone (DHA), [7α-3H]-androstenedione and [7α-3H]testosterone was studied in the ventral sebaceous gland patch of the Mongolian gerbil in vitro. The main enzyme activities found were 17β-hydroxysteroid dehydrogenase, 5α-reductase, 17α-hydroxysteroid dehydrogenase, 3α-hydroxysteroid dehydrogenase, sulphotransferase and hydroxylase. The active androgen 5α-dihydrotestosterone was formed in appreciable amounts from both testosterone and androstenedione. The 17β-hydroxysteroid dehydrogenase actively formed both 17-oxo and 17β-hydroxysteroids in this tissue. The conversion of DHA to C4–5 unsaturated steroids and 5α-steroids was not observed presumably due to a lack of 3β-hydroxysteroid dehydrogenase Δ4–5isomerase. The metabolism was compared with that in human and rat skin and its significance discussed.
THE EFFECT OF SYNTHETIC HYPOTHALAMIC RELEASING FACTORS ON PLASMA LEVELS OF LUTEINIZING HORMONE IN THE COCKEREL
Authors: FURR B. J. A. , ONUORA G. I. , BONNEY ROSEMARY C. , CUNNINGHAM F. J. 
Published: December 2008

SUMMARY
The capacity of synthetic luteinizing hormone releasing factor (LH-RF) to stimulate the release of luteinizing hormone (LH) from the pituitary gland of the cockerel has been examined. Administration of LH-RF to 21 intact and 12 castrated cockerels aged between 14 and 20 months resulted in a rapid increase in the levels of LH in the plasma within 5–10 min of injection in both groups of birds. Plasma LH then declined rapidly and returned to basal values within 1 h. The amount of LH released in the intact birds was dependent on the dose of LH-RF. Concentrations of LH in the plasma did not increase after injection of thyroid-stimulating hormone releasing factor but the response of the pituitary gland to a subsequent injection of LH-RF 2 h later was not altered. The pattern of release of LH in the cockerel is compared with that of some mammalian species.
EFFECT OF HYPOTHALAMIC RELEASING FACTORS AND STEROIDS ON RELEASE OF GONADOTROPHINS BY ORGAN CULTURES OF HUMAN FOETAL PITUITARIES
Authors: GROOM G. V. , BOYNS A. R. 
Published: December 2008

SUMMARY
Release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from organ cultures of human foetal pituitaries was stimulated by ovine hypothalamic extract (OHE), synthetic gonadotrophic hormone releasing factor and dibutyryl cyclic AMP. In each case, LH release was greater than that of FSH. Synthetic gonadotrophic hormone releasing factor produced an increase in the total FSH and LH content of the cultures.
Oestradiol-17β stimulated release of FSH but not LH. Testosterone, progesterone and 5α-dihydrotestosterone were without effect on hormone release. Chronic exposure of cultures to progesterone prevented stimulation of hormone release by OHE. Long-term contact with oestradiol-17β did not modify tissue sensitivity to OHE.
KINETIC STUDIES ON THE ENZYMES CATALYSING THE CONVERSION OF 17α-HYDROXY-PROGESTERONE AND DEHYDROEPIANDROSTERONE TO ANDROSTENEDIONE IN THE HUMAN ADRENAL GLAND IN VITRO
Authors: YATES JEAN , DESHPANDE N. 
Published: December 2008

SUMMARY
Factors controlling the synthesis of androstenedione in the human adrenal gland were investigated in a kinetic study of the enzymes catalysing the conversion of 17α-hydroxyprogesterone and dehydroepiandrosterone to the hormone. Both reactions are associated with the microsomal fraction of the adrenal cell. 17α-Hydroxyprogesterone is converted to androstenedione by a NADPH-dependent 17-desmolase whereas there is an obligatory requirement for NAD+ for the conversion of dehydroepiandrosterone to the hormone. None of the other cofactors investigated inhibited or enhanced the enzymic conversions.
The side-chain cleavage of 17α-hydroxyprogesterone was competitively inhibited by the precursors of the substrate, pregnenolone, progesterone and 17α-hydroxypregnenolone. Other C19 or C18 compounds known to be synthesized by the human adrenal gland were found to be ineffective in modifying the enzyme action. The conversion of dehydroepiandrosterone to androstenedione was non-competitively inhibited by oestrone and oestradiol-17β. No C21 compounds were found to affect the reaction. 5α-Dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) inhibited both enzymic conversions competitively but the inhibition constants observed were so high that it is unlikely that this finding has any relevance to the control of androstenedione synthesis in vitro.
CHORIONIC GONADOTROPHIN IN THE HUMAN PLACENTA IN RELATION TO THE SEX OF THE FOETUS AT TERM
Authors: HOBSON BRUCE , WIDE LEIF 
Published: December 2008

SUMMARY
Human chorionic gonadotrophin (HCG) was assayed by biological and radioimmunological methods in 40 human term placentae. It was found that the concentration of HCG per g and per placenta was lower when the sex of the foetus was male than when it was female. This difference is significant (P < 0·005) and applies to the results obtained both in the biological and the radioimmunological assays.
THE MECHANISM OF ANDROGEN UPTAKE AND CONCENTRATION BY RAT VENTRAL PROSTATE IN ORGAN CULTURE
Authors: LASNITZKI ILSE , FRANKLIN HILARY R. , WILSON JEAN D. 
Published: December 2008

SUMMARY
The uptake and metabolism of [1,2-3H]dihydrotestosterone and [1,2-3H]-testosterone by explants of rat ventral prostate maintained in organ culture have been assessed under circumstances in which constant intracellular levels of the hormones have been achieved. Dihydrotestosterone was the principal intracellular androgen whether the hormone in the incubation medium was testosterone or dihydrotestosterone, and intracellular to extracellular gradients for dihydrotestosterone were greater than those for testosterone under all conditions studied. These findings are compatible with the possibility that the conversion of testosterone to dihydrotestosterone and the subsequent binding of dihydrotestosterone to receptor sites within the tissue serve to keep the activity of intracellular testosterone low and to promote passive diffusion down an activity gradient from blood. The net effect of such a system is the development in the prostate of a higher concentration of total androgen (testosterone plus dihydrotestosterone) than in the medium.
THE CONCENTRATIONS OF ANDROGENS, OESTROGENS, PROGESTERONE AND LUTEINIZING HORMONE IN THE SERUM OF FOETAL CALVES THROUGHOUT THE COURSE OF GESTATION
Authors: CHALLIS J. R. G. , KIM C. K. , NAFTOLIN F. , JUDD H. L. , YEN S. S. C. , BENIRSCHKE K. 
Published: December 2008

SUMMARY
The concentrations of luteinizing hormone (LH), progesterone, testosterone, androstenedione, oestrone and oestradiol in mixed umbilical cord blood taken from foetal calves during months 3 to 9 of gestation have been measured by radioimmunoassay. The levels of progesterone were low (compared with those in maternal plasma) and constant during pregnancy. There were large variations in the concentrations of androstenedione, oestrone, oestradiol and LH, with lower values found during months 7 to 8 of gestation. Significant differences (P < 0·05–< 0·001) in hormone levels between male and female foetuses were found for testosterone, LH, and the oestrogens during months 3 to 7, 3 and 4, and 7 and 8, respectively. No significant differences (P > 0·05) between sexes were found at any time between the concentrations of progesterone and androstenedione.
EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON TESTOSTERONE SECRETION BY THE FOETAL HUMAN TESTIS IN ORGAN CULTURE
Authors: ABRAMOVICH D. R. , BAKER T. G. , NEAL P. 
Published: December 2008

SUMMARY
Foetal human testes (12–22 weeks gestation), maintained in organ culture, were treated with human chorionic gonadotrophin (HCG) and the amount of testosterone produced compared with control cultures. In all cases the testes produced testosterone, but from the 13th to 18th week of gestation significantly more testosterone was produced by, and the Leydig cell hyperplasia was maintained in, the HCG stimulated organ cultures. It is suggested that HCG is ultimately responsible for differentiation of the human male external genitalia.
CONVERSION OF PROGESTERONE TO ANDROGENS BY NON-FLAGELLATE GERMINAL CELLS ISOLATED FROM SEMINIFEROUS TUBULES OF RAT TESTIS
Authors: GALENA H. J. , TERNER C. 
Published: December 2008

SUMMARY
A method is described for the isolation of non-flagellate germinal cells of the testis. The interstitial cells were removed by submersion of teased seminiferous tubules in distilled water. The interstitial cells exposed to water burst while the germinal cells inside the tubules remained intact. The tubules were then homogenized in isotonic saline and the non-flagellate germinal cells (spermatocytes and young spermatids) were isolated by centrifugation and filtration through a layer of Sephadex G-25 gel. On incubation with progesterone these cells produced 17α-hydroxyprogesterone, androstenedione, and testosterone. The rate of conversion of progesterone to testosterone in vitro was 0·20 μg/h/109 germinal cells. These results suggest that the non-flagellate germinal cells of the testis may make a significant contribution to the production of androgens.
HUMAN FOETAL SYNTHESIS OF TESTOSTERONE FROM PERFUSED PROGESTERONE
Authors: TAYLOR T. , COUTTS J. R. T. , MACNAUGHTON M. C. 
Published: December 2008

SUMMARY
Two male and four female human foetuses of 16–20 weeks gestation were perfused with [4-14C]progesterone. Subsequently, testosterone and androstenedione bearing a 14C-label were isolated in significant amounts from the testes and adrenals, respectively, of the male foetuses. Both C19-steroids were also isolated from the perfusate of one of the male foetuses. Neither C19-steroid was present in the livers of the male foetuses or in the ovaries, adrenals, livers or perfusates of the female foetuses.
It is concluded that the mid-term male foetus can readily synthesize testosterone from the large amounts of progesterone of placental origin present in the foetal circulation. The results suggest that the conversion is primarily a testicular function, but a direct or indirect adrenal involvement cannot be excluded.
SPECIFIC RELEASE OF BOVINE NEUROPHYSIN I DURING MILKING AND SUCKLING IN THE COW
Authors: LEGROS J. J. , REYNAERT R. , PEETERS G. 
Published: December 2008

SUMMARY
Using continuous blood sampling a specific release of neurophysin I without a significant release of neurophysin II was found during hand-milking and suckling in seven out of eight cows. Hand-milking appeared to be a slightly more powerful stimulus than suckling.
SHORT-TERM EFFECTS OF COPULATION, HUMAN CHORIONIC GONADOTROPHIN INJECTION AND NON-TACTILE ASSOCIATION WITH A FEMALE ON TESTOSTERONE LEVELS IN THE MALE RAT
Authors: PURVIS K. , HAYNES N. B. 
Published: December 2008

SUMMARY
Peripheral plasma testosterone levels in the male rat were increased above control levels 5 min after the first intromission with an oestrous female, or 8–10 min after first contact with the female. The levels remained raised for at least 30 min if copulation was allowed to continue. Intravenous injection of human chorionic gonadotrophin resulted in an increased peripheral concentration of plasma testosterone after 10–15 min and an increase of testosterone content of the testis 5–10 min after injection, indicating that the rat testis has a potential to respond rapidly to gonadotrophin. The results suggested that if the testosterone surge during copulation was gonadotrophin-dependent, it was initiated before the first intromission. Indeed, plasma testosterone levels were raised in male rats 5 min after being placed in the proximity of oestrous females but not allowed physical contact.
SOME EFFECTS OF VASOPRESSIN ON SEXUAL BEHAVIOUR AND SEMINAL CHARACTERISTICS IN INTACT AND CASTRATED RABBITS
Authors: KIHLSTRÖM J. E. , ÅGMO A. 
Published: December 2008

SUMMARY
The effect of intravenous injections of vasopressin upon sexual behaviour was studied in both intact and castrated, testosterone-treated rabbits. A high dose of vasopressin reduced the number of ejaculations and lengthened the latency to the first mount and ejaculation. A low dose of vasopressin had no significant effect on the sexual behaviour in either intact or castrated rabbits. The volume of ejaculates and the number of sperm cells were also determined. It was found that vasopressin (200 or 40 mu./animal) significantly increased both volume and sperm content in the ejaculates. The possibility that vasopressin is of physiological importance in male sexual functions is discussed.
THE EFFECT OF BETAMETHASONE ON GLUCOSE PRODUCTION AND ON GLUCONEOGENESIS FROM AMINO ACIDS IN SHEEP
Authors: REILLY P. E. B. , FORD E. J. H. 
Published: December 2008

SUMMARY
Primed continuous infusions of tracer amounts of [U-14C]glucose and of [U-14C]labelled mixed amino acids were used to measure plasma glucose and amino acid entry rates and to obtain an index of the incorporation of amino acid carbon into glucose by sheep before and 24 h after a single intramuscular injection of betamethasone.
Maximum hyperglycaemia occurred 24 h after administration of the steroid, but there was no significant change in arterial amino acid concentration. Mean glucose entry rate was significantly raised 24 h after steroid administration. The rate of incorporation of amino acid carbon into glucose also increased significantly. The increases in plasma glucose concentration and in glucose entry confirm the authors' previous results. The results also indicate that a significant proportion of the additional glucose entry is synthesized from amino acid carbon.
PROLACTIN RECEPTORS: CHARACTERISTICS OF THE PARTICULATE FRACTION BINDING ACTIVITY
Authors: FRANTZ W. L. , MacINDOE J. H. , TURKINGTON R. W. 
Published: December 2008

SUMMARY
Ovine 125I-labelled prolactin was incubated with a membrane-rich particulate fraction of mouse mammary gland and bound hormone was separated by centrifugation and washing. The experiments identified two types of binding activity: total binding and specific binding, the fraction of the total which could be displaced competitively by native prolactin but not by a number of other polypeptides. Two other lactogenic hormones, human chorionic somato-mammotrophin and human growth hormone, displaced 125I-labelled prolactin in proportion to their known intrinsic lactogenic activities. Binding of 125I-labelled prolactin was complete within 20 min at 4 or 37 °C. Scatchard analysis of the binding indicated an apparent dissociation constant (Kd) of approximately 9 × 10−9 mol/l and a concentration of binding sites of 15·5 × 10−13 mol/mg particulate protein. The greatest rate of specific displacement of bound 125I-labelled prolactin was observed at concentrations of prolactin between 50 and 250 ng/ml, a concentration range near the mid-point of the dose—response curve of casein induction in intact mammary cells. The saturating concentration of prolactin for specific binding to mammary particles was similar to that for casein induction in intact cells. The prolactin binding activity was sensitive to treatment with trypsin or heating at 70 °C, indicating its protein nature. These properties of the mammary prolactin binding activity are those required of a receptor for prolactin or other lactogens. Prolactin-specific binding activity was also found in particles from mouse liver, kidney, and midbrain and from the ovary, adrenal, and seminal vesicle of the rat. These results suggest a fairly widespread tissue distribution of the prolactin receptor, and potentially implicate prolactin in the hormonal regulation of these organs.
EFFECT OF GONADAL STEROIDS ON THE PITUITARY RESPONSIVENESS TO SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE IN THE MALE DOG
Authors: JONES GWYNETH E. , BOYNS A. R. 
Published: December 2008

SUMMARY
Intravenous injections of synthetic luteinizing hormone releasing hormone (LH-RH) stimulated LH secretion in male dogs. An i.m. injection of 0·025–2·5 mg oestradiol-17β given 2·5 h but not 24 h before administration of LH-RH blocked LH secretion. Diethylstilboestrol (2·5 mg) also blocked LH secretion but meso-dihydrodibutylstilboestrol (2·5 mg) was without effect. Testosterone (2·5 and 25 mg), dihydrotestosterone (2·5 mg), 5α-androstane-3α, 17β-diol (2·5 mg), 5α-androstane-3β, 17β-diol (2·5 mg), 5α-androstane-3α, 17α-diol (0·125 mg), 5α-androstane-3β, 17α-diol (0·125 mg) and progesterone (25 and 50 mg) did not prevent LH-RH stimulation of LH secretion.
THE EFFECT OF OXYTOCIN ON SPERM TRANSPORT IN OVARIECTOMIZED, OESTROGEN-TREATED RABBITS
Authors: MORTON D. B. , FITZPATRICK R. J. 
Published: December 2008

SUMMARY
Ovariectomized, oestrogen-primed rabbits were injected intravenously with varying doses of oxytocin immediately after insemination with a standardized inseminate. The does were killed 30 min after insemination and the number of spermatozoa in different segments of the genital tract was determined. The most significant finding was that when 80 mu. oxytocin were given, mass transport of semen into the uterus occurred. This suggests a coordinated response of the genital tract to a critical oxytocin stimulus which facilitates mass transcervical passage of fluids. However, when 80 mu. oxytocin were given to intact oestrous rabbits, no significant effect on sperm transport was detected.
THE EFFECT OF HUMAN PLACENTAL LACTOGEN ON ADIPOSE TISSUE LIPOLYSIS
Authors: STRANGE R. C. , SWYER G. I. M. 
Published: December 2008

SUMMARY
The lipolytic activity of human placental lactogen (HPL) was measured using adipose tissue pieces and free fat-cell suspensions. HPL in non-physiological concentrations stimulated lipolysis after a latent period of 2 h. The preincubation of tissue pieces with HPL in physiological concentrations (8 μg/ml) increased the rate of theophylline-stimulated lipolysis.