bluuebunny/crossref_metadata_2025_split huggingface dataset:
MAINTENANCE OF PREGNANCY BY SYNTHETIC PROGESTAGENS IN GUINEA-PIGS OVARIECTOMIZED BEFORE IMPLANTATION; PROGESTERONE-BINDING PROTEIN AND PLACENTAL PROGESTERONE SECRETION
Authors: ILLINGWORTH DOREEN V. , DEANESLY RUTH 
Published: December 2008

SUMMARY
In guinea-pigs ovariectomized before implantation, pregnancy can be maintained during the first 3 or 4 weeks, a critical period of early growth, by synthetic progestagens that do not metabolize to progesterone (norgestrel, medroxyprogesterone acetate and melengestrol acetate). It follows that peripheral plasma progesterone levels are related to placental progesterone secretion. There were indications that progesterone secretion by the placenta begins as early as day 16–18 of pregnancy. In the experimental animals the plasma progesterone levels, measured by a competitive protein-binding technique, were 9·4 ± 2·07 ng/ml (mean ± s.e.m.; n = 18) by days 20–22 of pregnancy; they continued to rise and reached 26·4 ± 3·88 ng/ml (n = 8) by days 27 to 29.
The metabolic clearance rate of progesterone measured in four pregnant ovariectomized animals with progesterone or progestagen implants, was < 10 l/day as in normal pregnant animals. The calculated production rates of progesterone in the experimental animals (0·1 to 0·35 mg/day) reflect the placental production rate of progesterone. A simple 'assay' is described for the high affinity progesterone-binding protein of pregnancy (progesteronebinding globulin).
ANDROGEN-INDUCED CELL PROLIFERATION AND DIFFERENTIATION IN THE SEMINAL VESICLE AND COAGULATING GLAND OF THE CASTRATED MOUSE
Authors: MORLEY A. R. , WRIGHT N. A. 
Published: December 2008

SUMMARY
Castrated male mice were injected with 250 μg testosterone propionate on 3 consecutive days. With the third injection, 1 μCi tritiated thymidine/g body weight was given intraperitoneally. A pulse-chase analysis in the seminal vesicle and coagulating gland was performed during the next 50 h and labelling and mitotic indices were obtained.
One hour after the injection of tritiated thymidine the labelling index was 19% in the seminal vesicle and 13% in the coagulating gland. The mitotic index was 1·7% in the seminal vesicle and 1·4% in the coagulating gland.
The observed cell cycle (Tc) duration in the seminal vesicle was 25 h, and the duration of DNA synthesis (ts) was 9 h. The calculated duration of mitosis (tm) was 0·6 h, the presynthetic duration (tG1) was 14·2 h, and the postsynthetic duration (tG2) 1·2 h. Forty-eight hours after testosterone propionate the growth fraction was 0·62 and a decycling ratio of 0·8 was calculated. In the coagulating gland Tc was 52·0 h, ts 9·0 h, tm 1·0 h, tg1 41·0 h and tG2 1·0 h.
SOME LIGHT- AND ELECTRON-MICROSCOPICAL OBSERVATIONS ON THE PARS TUBERALIS OF THE PITUITARY GLAND OF THE RABBIT
Authors: CAMERON E. , FOSTER C. L. 
Published: December 2008

SUMMARY
The cytological appearance of the pars tuberalis both at the light- and the electron-microscopical levels is described. Two main types of cell, one, which is designated the tuberalis cell, having a rounded contour, pale cytoplasm with a few small secretory granules of about 100 nm in diameter, many polyribosomes and a relatively large ovoid nucleus; and the other, the interstitial cell, with long processes often encircling tuberalis cells, an irregular nucleus and cytoplasm with abundant microfilaments about 10 nm in diameter were seen. Beaded nerve fibres and neurosecretory material were demonstrated in the pars tuberalis with chrome alum—haematoxylin, a finding confirmed at the electron-microscopical level where nerve fibres which appeared to be making contact with tuberalis cells and containing numerous microvesicles of about 50 nm in diameter were observed.
OSTEOPOROSIS AFTER OOPHORECTOMY IN THE MATURE FEMALE RAT AND THE EFFECT OF OESTROGEN AND/OR PROGESTOGEN REPLACEMENT THERAPY IN ITS PREVENTION
Authors: AITKEN J. M. , ARMSTRONG E. , ANDERSON J. B. 
Published: December 2008

SUMMARY
Fifty-two mature female rats on a controlled diet were studied to compare the effects of oophorectomy, and hormone replacement therapy after oophorectomy, on femoral morphology and mineral content. Oophorectomy was followed by the development of osteoporosis after 11 months of observation. This was characterized by a reduction in ash per unit length of bone and a diminution of mid-shaft femoral cortical width. The administration of a progestogen (9 μg ethynodiol diacetate/rat/day) for 10 months after oophorectomy prevented the reduction in ash per unit length from occurring, whereas an oestrogen (0·9 μg mestranol/rat/day) had no significant effect on either parameter of osteoporosis. The progestogen appeared to produce this effect by a relative increase in periosteal new bone formation at the expense of increased loss of bone from the endosteal surface.
PROGESTATIONAL STEROIDS DURING PSEUDOPREGNANCY IN THE RABBIT
Authors: HORRELL ELISABETH , MAJOR PATRICIA W. , KILPATRICK R. , SMITH BRENDA M. 
Published: December 2008

SUMMARY
The secretion of progestational steroids by the rabbit ovary was examined during pseudopregnancy. Progesterone secretion rose up to the mid-period but exceeded secretion of 20α-dihydroprogesterone only on days 7 and 9. The development of the corpus luteum and interstitial tissue and their content of progestational steroids were also examined during this period. The progesterone content of corpus luteum tissue fell towards the end of pseudopregnancy, while the corpora lutea remained large. Levels of 20α-dihydroprogesterone were generally higher in the interstitial tissue after the first few days. A significant alteration in the pattern of steroid synthesis and secretion occurred at a time corresponding to the period of implantation in the pregnant rabbit.
SELECTIVE BREEDING FOR VARIATIONS IN THYROIDAL IODINE RELEASE RATE IN MICE
Authors: CHAI C. K. , MELLOH ANN 
Published: December 2008

SUMMARY
Mice were selectively bred for high and low thyroidal 131I release rates. Two lines with sharp contrast in the selection criterion were produced, and an estimate of heritability was made. There were correlated differences in thyroid histology, protein-bound 131I, cholesterol level, haematocrit, adrenal and testicular weights, and some behavioural characteristics. It was concluded that multiple genetic factors affect the rate of thyroidal iodine release, and that the high release strain had greater thyroid activity than the low release strain. Some genetic aspects of thyroid function are discussed.
INFLUENCE OF PHOTOPERIOD ON OESTROGENIC INDUCTION OF NEST-BUILDING IN CANARIES
Authors: STEEL ELIZABETH , HINDE R. A. 
Published: December 2008

SUMMARY
A 20h light:4h darkness lighting schedule induced a high level of gathering behaviour in intact canary hens in autumn and winter. The same schedule was relatively ineffective in ovariectomized birds, indicating that the ovary is normally a mediator in the photostimulation of nest-building behaviour. However, exogenous oestrogen given to ovariectomized birds on normal winter daylengths resulted in only a slight increase in gathering behaviour, while in similar birds previously exposed for 5 weeks to a 20h light: 4h darkness schedule a rapid increase in gathering occurred to a level approaching that of intact birds on long photoperiods. A similar difference in response to hormone injection with and without exposure to long photoperiods was also seen with testosterone and with oestrogen and testosterone in combination.
Nest-building was not completely eliminated in ovariectomized birds. Ovariectomized birds on 20h light:4h darkness per day gathered more than those on normal daylengths. This is unlikely to be a consequence of the longer time available for building activity as it can be suppressed in the long-photoperiod birds by methallibure, a gonadotrophin inhibitor. The possibility that a non-ovarian mechanism is involved in building behaviour is discussed.
The results suggest that although the effect of long photoperiods on nest-building is mediated largely by oestrogen there is a second factor operating without which oestrogen is relatively ineffective. Possible mechanisms for this effect are discussed.
A COMPARISON BETWEEN CHORIONIC GONADOTROPHINS EXTRACTED FROM HUMAN, RHESUS MONKEY AND MARMOSET PLACENTAE
Authors: HOBSON BRUCE , WIDE LEIF 
Published: December 2008

SUMMARY
Evidence is provided to show that chorionic gonadotrophins extracted from the human, rhesus monkey and marmoset placentae have antigenic determinants in common. Similar slopes were obtained for these gonadotrophins in a radioimmunoassay for human chorionic gonadotrophin (HCG). The biological activity of the monkey gonadotrophins was neutralized by anti-HCG serum. When the gonadotrophic activity of the monkey placental extracts was assayed biologically and immunologically, using HCG as a standard, similar results were obtained. Higher values were obtained by the immunoassay than by the bioassay when extracts of human placenta were assayed using the same HCG standard.
NEONATAL ADRENOCORTICAL FUNCTION AND ITS POSSIBLE RELATION TO THE UPTAKE OF MACROMOLECULES BY THE SMALL INTESTINE OF THE GUINEA-PIG AND RABBIT
Authors: MALINOWSKA K. W. , HARDY R. N. , NATHANIELSZ P. W. 
Published: December 2008

SUMMARY
Plasma cortisol and corticosterone were separated by Sephadex LH-20 chromatography. The high concentration of plasma cortisol immediately after birth in the guinea-pig coincided with the decline in 125I-labelled polyvinyl pyrrolidone (PVP) uptake (closure) between 48 and 72 h. Similarly, in the rabbit, plasma cortisol concentration was increasing at the time of closure, 18–21 days after birth. These results suggest that there is a correlation between the time when the concentration of the main plasma adrenocortical steroid rises and the time when the neonatal small intestine ceases to take up PVP.
GENETIC ANALYSIS OF PLASMA CORTICOSTERONE LEVELS IN TWO INBRED STRAINS OF MICE
Authors: ELEFTHERIOU B. E. , BAILEY D. W. 
Published: December 2008

SUMMARY
Plasma corticosterone levels were determined fluorometrically in mice of two unrelated highly inbred strains, C57BL/6By and BALB/cBy, and in seven of their derived recombinant-inbred strains as well as their F1 hybrid and backcross generations necessary to arrive at a genetic model for plasma corticosterone levels. It was concluded that the simplest genetic model, and one which fits the experimental results, was one which assumed that plasma corticosterone levels are controlled genetically by two loci with the epistatic interaction indicating dependency of pathways of action for the two genes.
PROLONGATION OF PSEUDOPREGNANCY IN THE RAT BY SLITTING THE UTERUS
Authors: PAKURAR ALICE SWOPE , ROTHCHILD I. 
Published: December 2008

SUMMARY
On day 9 of dioestrus the uteri of pseudopregnant rats bearing deciduomata were either slit lengthwise to curette out the decidual tissue or were removed in toto to determine if the prolonging effect of decidualization on pseudopregnancy could be eliminated. Both operations significantly reduced the length of the pseudopregnancy dioestrus (combined mean of 19·3 ± 0·56 days v. 22·2 ± 0·77 days for rats with intact deciduomata; P < 0·01). Conversely, the control experiment of slitting the non-decidualized uterus on day 9 significantly prolonged pseudopregnancy in comparison with control groups (19·2 ± 0·92 days v. 13·5 ± 0·37 days for pseudopregnant controls which were not subjected to operation, or had a laparotomy or uterine traumatization performed on day 9; P < 0·001). The effect of slitting the uterus on other days of pseudopregnancy was investigated. The mechanism through which slitting prolongs pseudopregnancy is unknown.
CHARACTERISTICS OF FAST FEEDBACK CONTROL OF CORTICOTROPHIN RELEASE BY CORTICOSTEROIDS
Authors: JONES M. T. , BRUSH F. R. , NEAME R. L. B. 
Published: December 2008

SUMMARY
Corticosterone was administered intraperitoneally to rats, and the consequent changes in plasma corticosterone concentration traced. Stress (sham bilateral adrenalectomy) was applied at various times when the plasma corticosterone concentration was changing at different rates, and it was shown that there was a critical rate of rise of plasma corticosterone concentration of about 1·3 μg/100 ml plasma/min in excess of which the stress response was inhibited. Rates of rise less than this did not affect the stress response. A state of ' saturation' of the control system was also demonstrated to result from high plasma corticosterone concentrations when the response to stress was not inhibited as above. A model of the system is suggested to explain these and other data.
REGULATION OF INSULIN SECRETION IN THE OVINE FOETUS IN UTERO. EFFECTS OF SODIUM VALERATE ON SECRETION AND OF ADRENOCORTICOTROPHIN-INDUCED PREMATURE PARTURITION ON THE INSULIN SECRETORY RESPONSE TO GLUCOSE
Authors: BASSETT J. M. , THORBURN G. D. , NICOL DIANNE H. 
Published: December 2008

SUMMARY
Intravenous infusions of glucose into lambs in utero (130–150 days) and after birth, confirmed the marked post-natal increase in the magnitude of the response of plasma insulin to glucose. These studies also suggest that insulin secretion in foetal lambs is stimulated by glucose at lower plasma concentrations than in lambs after birth. The short-chain fatty acid, valeric acid, given as the sodium salt, caused a very rapid increase in the plasma insulin level of foetal lambs, when given either by intravenous injection or infusion. When birth was induced after only 135 days of gestation by i.v. infusion of a synthetic adrenocorticotrophin preparation (Synacthen) into foetal lambs there was also a prematurely induced maturation of the insulin secretory response to glucose. In these prematurely born lambs the insulin secretory response to i.v. glucose infusion was similar to that of normal lambs after birth and differed greatly from that of normal foetuses of similar age.
The results indicate that maturation of the insulin secretory mechanism in the lamb is associated with parturition and suggest that these changes may be consequences of the increasing corticosteroid secretion in the foetus during the last few days of gestation.
THE EFFECT OF THYROTROPHIC RELEASING FACTOR ON DIFFERENT HYPOTHALAMIC AREAS AND THE ANTERIOR PITUITARY GLAND: A BIOCHEMICAL AND ULTRASTRUCTURAL STUDY
Authors: MOGUILEVSKY A. , CUERDO-ROCHA SILVIA , CHRISTOT JANINE , ZAMBRANO D. 
Published: December 2008

SUMMARY
A study on the effect of synthetic thyrotrophic releasing factor (TRF) on different areas of the central nervous system and on the anterior pituitary gland was performed in a system in vitro. These observations were combined with ultrastructural studies of the anterior pituitary gland after intracarotid TRF administration. TRF specifically decreased the incorporation in vitro of labelled amino acids into proteins of the medial hypothalamus, whereas the anterior pituitary gland showed enhanced protein synthesis. At the electron microscope level, only thyrotrophs showed enhanced signs of activation after 5, 15 and 30 min of TRF administration, which consisted in hypertrophy of the rough endoplasmic reticulum and Golgi complexes associated with a marked increase in the number of secretory granules undergoing extrusion into the perivascular and extracellular spaces. These observations indicate that the medial hypothalamus may be related to regulatory mechanism(s) of TRF secretion. They provide further morphological identification of the thyrotrophs and corroborate that TRF acts on these cells by promoting release and synthesis of thyrotrophin.
HYPERTROPHY AND HYPERPLASIA IN THE MOUSE UTERUS AFTER OESTROGEN TREATMENT: AN AUTORADIOGRAPHIC STUDY
Authors: MARTIN L. , FINN C. A. , TRINDER GAIL 
Published: December 2008

SUMMARY
The uteri of untreated ovariectomized mice consisted almost entirely of myometrium and connective tissue stroma. After oestrogenic stimulation these tissues underwent marked hypertrophy, but showed little proliferation.
The luminal epithelium underwent marked hyperplasia, with most cells dividing twice to quadruple cell numbers by 35–40 h, when they made up 10–12% of the uterine tissue volume and 20% of the total uterine cell population. The proliferative response was rapid, highly synchronized and short-lived. The number of cells incorporating [3H]thymidine first increased 8·5 h after oestradiol-17β and by 13–16 h 60–70% were engaged in DNA synthesis. Up to 21 h cell-death was minimal. From 21 h onwards the proliferation rate declined and the rate of cell death increased. A second injection of oestrogen prevented the rise in death rate and produced a second smaller burst of DNA synthesis. Cells in DNA synthesis or mitosis were insensitive to oestrogen.
A smaller proliferative response occurred in the glands: only 25% of cells entered DNA synthesis after the first injection of oestradiol and none after the second. Gland cells appeared to die in situ and there was no evidence that they migrated into the luminal epithelium.
OESTROGEN SYNTHESIS FROM [4-14C—1,2-3H]TESTOSTERONE BY A 160000 g SUPERNATANT FROM BABOON PLACENTA AND BY POSTMICROSOMAL FRACTIONS
Authors: MILEWICH L. , AXELROD L. R. 
Published: December 2008

SUMMARY
A baboon placental homogenate was centrifuged at 160000 g for 70 min to give a microsomal fraction and a supernatant, which on further centrifugation at 260000 g for 110 min gave a first postmicrosomal fraction and a second supernatant. This supernatant was centrifuged at 260000 g for 210 min to afford a second postmicrosomal fraction and a third supernatant.
The incubation of the first supernatant with [4-14C—1,2-3H]testosterone gave androstenedione, 19-hydroxytestosterone, 19-hydroxyandrostenedione, 17β-oestradiol and oestrone; incubation with the postmicrosomal supernatants yielded androstenedione only. When the two postmicrosomal fractions were incubated with the substrate, both 17β-oestradiol and androstenedione were obtained as metabolites. The losses of tritium from 17β-oestradiol and from oestrone metabolites were consistent with previous findings.
DISAPPEARANCE OF ENDOGENOUS RENIN FROM THE CIRCULATION AFTER NEPHRECTOMY IN PREVIOUSLY HEPATECTOMIZED OR COLONECTOMIZED DOGS
Authors: AMERY A. , EYSKENS E. , DELOOZ H. , FAGARD R. 
Published: December 2008

SUMMARY
The changes in plasma renin concentration (PRC) were studied in dogs after hepatectomy and bilateral nephrectomy, and after colonectomy and bilateral nephrectomy in a control group of animals. In the colonectomized dogs the PRC averaged 9·4 ± 4·2 units/l at the moment of the removal of the second kidney (time zero) and decreased to 44% of this value in the sample withdrawn 15 min later, and to 20·6% after 1 h. In the hepatectomized dogs the PRC averaged 44·3 ± 29·2 units/l at time zero and decreased to 70·6% of this value within 15 min, and to 30·3% after 1 h.
The results showed that the dogs without a liver were still able to remove renin from the circulation, suggesting that other mechanisms of renin clearance were operative.
THE EFFECT OF METHYLCHOLANTHRENE ON BILIARY THYROXINE EXCRETION IN NORMAL AND GUNN RATS
Authors: BASTOMSKY C. H. , PAPAPETROU P. D. 
Published: December 2008

SUMMARY
Biliary fistulae were produced in rats given [125I]thyroxine (T4) 18 h previously. Treatment of normal animals with 3-methylcholanthrene (MCA) raised the bile: plasma 125I ratio (B: P ratio) and biliary clearance of plasma 125I three times. All of the increase could be explained by enhanced excretion of T4-glucuronide.
In Gunn rats the B: P ratio and biliary clearance of plasma 125I was one quarter of normal and only a small fraction of biliary 125I was present as T4-glucuronide. In these animals MCA slightly, but significantly, enhanced the B: P ratio and biliary clearance of plasma radioactivity. The mechanism was not clear; it was not due to increased glucuronide formation and did not appear to be due to effects on the binding of T4 to plasma proteins.
MCA, in all the normal rats studied, lowered the serum protein-bound iodine (PBI), but in female Gunn rats it had no effect. Enhanced biliary excretion of T4 seemed to be responsible for the low serum PBI in MCA-treated normal rats. In normal male rats MCA increased thyroid 131I uptake, but had no effect in normal or Gunn female rats.
Injection of female mice with MCA reduced the half-life of circulating T4.
THE RELATIONSHIP OF THE SPLANCHNIC, HEPATIC AND RENAL CLEARANCE RATES TO THE METABOLIC CLEARANCE RATE OF CORTISOL IN CONSCIOUS SHEEP
Authors: PANARETTO B. A. , PATERSON J. Y. F. , HILLS F. 
Published: December 2008

SUMMARY
The uptake of cortisol by organs in the splanchnic area of conscious, undisturbed sheep was estimated before and during the administration of adrenocorticotrophic hormone (ACTH) by measuring cortisol concentration differences in portal and hepatic venous plasma and estimating hepatic plasma flow rates. Metabolic clearance rates (MCR) of plasma cortisol were measured simultaneously. The total splanchnic clearance of cortisol was 61% of MCR in the animal, 48% being accounted for by the liver. When ACTH was given there were increases in MCR and these were accompanied by proportional increases in hepatic plasma flow rates. When ACTH was infused the total splanchnic clearance rate was 65% of MCR, 52–59% being accounted for by the liver.
In other experiments the renal clearance rate of cortisol was studied. Under control conditions, and when ACTH was given, the renal clearance was 11% of MCR.
The relationship of the sum of individual clearances to MCR is compared and discussed.
DNA SYNTHESIS IN THE ENDOMETRIUM OF PROGESTERONE-TREATED MICE
Authors: MARTIN L. , FINN C. A. , TRINDER GAIL 
Published: December 2008

SUMMARY
[3H]Thymidine autoradiography was used to study DNA synthesis in the uteri of spayed mice treated with progesterone and oestradiol. Progesterone suppressed DNA synthesis in the glandular epithelium whether oestrogen was given or not. It also suppressed DNA synthesis in the luminal epithelium. Here oestradiol produced morphological changes and eventual re-entry of some cells into DNA synthesis.
Progesterone altered the nuclear morphology of the stromal cells and increased the number synthesizing DNA. In these conditions a single injection of oestrogen was followed 10–15 h later by the synchronized entry into DNA synthesis of 30–40% of stromal cells. However, a second injection produced no further response.
It was concluded that progesterone stimulated stromal cells in the resting phase to enter the cell cycle and that oestrogen then accelerated their passage through a single round of replication and division by shortening the interval between mitosis and DNA synthesis, following which the cells withdrew from the cell cycle.