bluuebunny/crossref_metadata_2025_split huggingface dataset:
BIOLOGICAL EFFECTS OF 131I AND 125I ISOTOPES OF IODINE IN THE RAT
Authors: DONIACH I. , SHALE D. J. 
Published: December 2008

SUMMARY
From the differences in radiation profiles between 131I and 125I isotopes of iodine it would be expected that they would show different effects on thyroid function. The differences should lead to lower rates of thyroid gland destruction with 125I and hence less post-irradiation hypothyroidism. This difference in biological effect has been demonstrated in rats by indirect assessment of thyroid function. In this report the long-term effects of a range of similar doses of 131I and 125I were compared, in male and female rats, by direct assessment of thyroid function. Seventeen months after receiving 25 and 125 μCi of 131I, male and female rats showed significant elevation of serum TSH concentration and a reduction in 3 h radioiodine uptake. Rats receiving 1 and 5 μCi of 131I and all doses of 125I showed no significant changes in thyroid function. These findings confirm the previously reported differences in effect between the 131I and 125I isotopes of iodine in the rat.
CONGENITAL GOITRE IN SHEEP: ISOLATION OF THE IODOPROTEINS WHICH REPLACE THYROGLOBULIN
Authors: DOLLING C. E. , GOOD B. F. 
Published: December 2008

SUMMARY
Immunological and chromatographic studies of proteins from the congenital goitre of South Australian Merino sheep revealed that normal thyroglobulin is absent from the thyroid glands of these sheep. However, a thyroglobulin-immunoreactive iodoprotein was isolated by affinity chromatography on agarose gel to which antibody against thyroglobulin had been covalently bound. Sucrose-gradient ultracentrifugation indicated that this iodoprotein had a sedimentation coefficient of 8S and a molecular weight of approximately 175000. This iodoprotein is therefore about one quarter the size of normal thyroglobulin (19S; 660000) and is similar in size to the subunit of thyroglobulin (3-8S; 165000) although this has usually been described as non-iodinated except when derived by reductive fission.
In addition the goitre extract contained iodoproteins which had the immunological properties of serum albumin and immunoglobulin G.
Determination of the iodine and iodoamino acid content of the hydrolysed iodoproteins revealed that they contained iodothyronines which were able to contribute to the production of thyroid hormones although the total iodothyronine content of the goitrous gland was less than that of the normal sheep thyroid gland.
OUTPUT OF OESTROGENS, TESTOSTERONE AND THEIR PRECURSORS BY ISOLATED HUMAN ADRENAL CELLS AS COMPARED WITH THAT OF GLUCOCORTICOSTEROIDS
Authors: KEYMOLEN V. , DOR P. , BORKOWSKI A. 
Published: December 2008

SUMMARY
The output of oestrogens, testosterone and their precursors was compared with that of glucocorticosteroids under standardized conditions, in a suspension of isolated human adrenal cells. Cortisol, corticosterone, androstenedione, dehydroepiandrosterone and its sulphate all increased in the same proportions after ACTH stimulation. The response to the logarithm of ACTH concentrations had a sigmoid shape but was fairly linear between 5 and 100 to 1000 μu./ml.
The output of dehydroepiandrosterone plus that of its sulphate was of the same order of magnitude as the production of cortisol; the output of free dehydroepiandrosterone averaged half that of the sulphate indicating that the adrenal cortex is capable, under certain conditions, of producing large amounts of the free steroid.
The output of androstenedione was very low, on average 35 times lower than that of cortisol, suggesting by extrapolation that the adrenal secretion may not be the main source of androstenedione in vivo or that ACTH is not the unique stimulus to adrenal androstenedione secretion.
The output of testosterone was small to negligible and that of oestrogens was practically absent.
In three additional experiments the influence of prolactin, prostaglandins, FSH and HCG was explored: no selective stimulation of androgen or oestrogen output was observed except in one experiment in which HCG stimulated adrenal testosterone production.
INFLUENCE OF 16-ARYLOXYPROSTAGLANDINS ON THE PRODUCTION OF PROGESTERONE BY HUMAN GRANULOSA CELLS IN VITRO
Authors: HENDERSON K. M. 
Published: December 2008

SUMMARY
16-Aryloxy analogues of prostaglandin F2α(PGF2α) are potent luteolysins in laboratory and farm animals. When their effect on progesterone production by luteinized human granulosa cells in tissue culture was investigated inhibition of both basal and gonadotrophin-stimulated progesterone production was observed, so revealing characteristics expected of potential human luteolysins. The analogues were, however, unable to inhibit progesterone production stimulated by PGE2, suggesting that like PGF2α these compounds may act by specifically blocking LH-activated adenylate cyclase.
The 16-aryloxyprostaglandins similarly inhibited progesterone production by porcine granulosa cells, so that the effects observed with the 16-aryloxyprostaglandins in vitro may be indicative of their potential in vivo.
PRODUCTION OF MALE PSEUDOHERMAPHRODITISM IN RATS BY TWO NEW INHIBITORS OF STEROID 17α-HYDROXYLASE AND C 17-20 LYASE
Authors: GOLDMAN A. S. , EAVEY R. D. , BAKER MARY K. 
Published: December 2008

SUMMARY
Two new synthetic steroid analogues, (I) 16β-bromo-3β,17α-dihydroxy-5α-pregnane-11,20-dione and (II) 17β-ureido-1,4-androstadien-3-one have been shown to give kinetic patterns consistent with active-site-directed irreversible inhibition of adult rat testicular microsomal steroid 17α-hydroxylase and C17-20 lyase in vitro. Administration of both analogues to adult male rats for 24 h produced potent inhibition of these testicular enzymes in vivo. Given to pregnant rats during the critical period of male organogenesis they produced hypospadias: a characteristic of the syndrome in man in which these enzymes are defective genetically. Given to male rat pups during the first 9 days of life, inhibitor II produced significantly smaller prostates and seminal vesicles in adulthood, indicating the usefulness of this inhibitor in studies on the role of testosterone in neonatal programming of target organ size in adulthood. Thus, two new enzyme inhibitors have been shown to block testosterone production in the foetal and neonatal rat selectively at the site of the hydroxylase without other apparent hormonal effects or influence on adrenal size.
INTERACTIONS OF OESTRADIOL-17β AND TAMOXIFEN IN THE UTERUS OF THE PREGNANT RAT
Authors: MAJOR J. S. , GREEN B. , HEALD P. J. 
Published: December 2008

SUMMARY
Measurement of the uptake and retention of a radioactive post-coital antifertility agent tamoxifen, by reproductive tissues of the rat have shown that the ovary retained more radioactivity than did any other reproductive organ. Studies have also been made of the uptake and distribution of [3H]tamoxifen and [3H]oestradiol-17β in the uterus of the pregnant rat on days 2–6 post coitum. Twenty-four hours after administration of tamoxifen, either i.v. or orally, 40–50% of the radioactivity was in the high speed pellet, 10–20% in the nuclear fraction, and 15–30% in the cytosol. An equivalent dose of [3H]oestradiol-17β yielded distributions of 5%, 5% and 82% respectively. Fractionation of uteri from animals given 0·2 mg tamoxifen/kg on Day 2 of pregnancy followed by [3H]oestradiol 60 min before death showed little difference in total uptake of oestradiol or distribution in the subcellular fraction on Days 4, 5 and 6. Although uptake of oestradiol by uterine nuclei was reduced on Day 3 by previous administration of tamoxifen on Day 2, appreciable quantities were still bound to the nuclear receptors. Treatment of ovariectomized animals with tamoxifen at doses up to 40 μg/rat (i.e. 0·2 mg/kg) led to the accumulation of oestrogen–receptor complex in the nucleus.
It is concluded that the antifertility properties of tamoxifen (under the conditions of these experiments) cannot be ascribed to the suppression of uptake and binding of oestradiol by the uterus.
EFFECT OF BRAIN STIMULATION ON ALDOSTERONE SECRETION IN THE RHESUS MONKEY (MACACA MULATTA)
Authors: FRANKEL R. J. , JENKINS J. S. , WRIGHT J. J. , KHAN M. U. A. 
Published: December 2008

SUMMARY
The lateral hypothalamus, and various sites within the limbic system and frontal lobe of the rhesus monkey brain were electrically stimulated using chronically implanted electrodes. A considerable increase in plasma aldosterone levels was observed after stimulation of the lateral hypothalamic area, certain localized sites in the cingulate area, and lower medial parts of the frontal lobe. Inactive sites included most of the amygdala, hippocampus, and basal ganglia, together with other areas within the frontal lobe and cingulate gyrus. Stimulation of all active areas was followed by an increase in plasma renin activity. Plasma cortisol also increased considerably after hypothalamic stimulation but in the case of extra-hypothalamic sites the cortisol response was much less.
EFFECTS OF PROPRANOLOL ON CHANGES IN HEART RATE, HEART WEIGHT, KIDNEY WEIGHT, URINARY HYDROXYPROLINE AND WEIGHT GAIN INDUCED BY LARGE DOSES OF THYROXINE IN THE RAT
Authors: GOULDING A. , McCHESNEY R. , STEWART R. D. H. 
Published: December 2008

SUMMARY
The effects of the β-adrenergic receptor blocking agent, dl-propranolol, and of the antithyroid drug, carbimazole, upon some manifestations of thyroxine (T4)-induced changes in peripheral metabolism were studied in rats. Propranolol lowered the heart rate, but did not alter the following changes induced by T4: increment in heart rate, increase in heart or kidney weight, increase in urinary hydroxyproline, decrease in body weight gain or increase in serum T4. Carbimazole administration lowered serum T4 and reduced weight gain, but had no effect upon heart rate or hydroxyproline excretion.
LUTEINIZING HORMONE RELEASE AFTER TWO INJECTIONS OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE IN THE EWE
Authors: CRIGHTON D. B. , FOSTER J. P. 
Published: December 2008

SUMMARY
Anoestrous ewes were given two injections of 30 μg synthetic luteinizing hormone releasing hormone (LH-RH) separated by one of the following intervals: 1·5, 3, 6, 12 or 24 h. The first injection caused an increase in the plasma LH concentration in each animal. The response to the second injection was dependent on the interval between the injections. When the second injection was administered 1·5 h after the first it caused a further increase in the LH concentration to maximal levels which were significantly greater than those induced in the other anoestrous groups. When the second injection was administered 3 h after the first, there was no significant difference between the responses to the two injections although the time to reach the maximal LH concentration was shorter and the height of the LH peak was greater in each animal following the second injection. When the second injection was administered 6,12 or 24 h after the first, the LH response was significantly less, in terms of height and area of the induced peak, than following the first injection. The LH response to the second injection was particularly low in the 12 and 24 h groups. Two injections of 30 μg synthetic LH-RH were also administered at 1·5 h intervals to ewes on either day 10 of the oestrous cycle or at onset of oestrus. The pattern of LH responses in all these animals was similar to that observed in anoestrous ewes injected at 1·5 h intervals. The total LH release, as assessed in terms of area of the induced peaks, was significantly greater in the onset of oestrus group than in the day 10 group or any of the anoestrous groups.
Presumably the sensitization–desensitization sequence of the pituitary gland to LH-RH which has been demonstrated, together with the effects of sex steroid hormones, must play an important part in the development and decay of the natural preovulatory LH peak.
IN-VITRO STUDIES OF NORMAL HUMAN THYROID CELLS: RESPONSES TO THYROTROPHIN AND DIBUTYRYL CYCLIC AMP
Authors: BIDEY S. P. , MARSDEN P. , ANDERSON J. , McKERRON C. G. , BERRY H. 
Published: December 2008

SUMMARY
Follicular cells isolated from normal human thyroid tissue have been cultured for up to 140 h with bovine thyrotrophin (TSH) or dibutyryl cyclic AMP (DBcAMP). Both compounds induced marked reorganization of the cells into three-dimensional follicular structures, whilst non-supplemented cells assumed a monolayer form.
Cultures treated initially with TSH or DBcAMP showed a greater iodide uptake capacity, in comparison with unsupplemented cultures, in which iodide uptake was markedly diminished after 24 h.
The release of tri-iodothyronine (T3) and thyroxine (T4) into the medium was determined by radioimmunoassay. Both TSH- and DBcAMP-treated cells showed a significant increase in iodothyronine output compared with unsupplemented control cells.
In contrast to the 'classical' TSH-induced depression of the T4:T3 ratio in vivo, an increase in the ratio was observed for both TSH- and DBcAMP-supplemented cells in vitro. The ratio was also significantly greater after TSH than after DBcAMP, and possible implications of this finding are discussed.
OESTROGEN-INDUCED CHANGES IN THE SECRETION OF LUTEINIZING HORMONE CAUSED BY CONTINUOUS INFUSIONS OF LUTEINIZING HORMONE RELEASING HORMONE IN THE LONG-TERM OVARIECTOMIZED RAT
Authors: SCHUILING G. A. , GNODDE H. P. 
Published: December 2008

SUMMARY
Oestrogen-induced changes in luteinizing hormone secretion, caused by continuous infusions of luteinizing hormone releasing hormone (LH-RH), appear to depend on the duration of exposure of the pituitary gland to the releasing hormone.
The initial oestrogen-induced depression of the potential response of the pituitary gland to LH-RH, which always seems to occur, does not necessarily turn into an enhancement of this potential response. It is suggested that this may be due to the fact that the response of the pituitary gland to LH-RH infusions is a continuously changing parameter influenced by oestrogen.
IMMUNOCHEMICAL CHARACTERIZATION OF GASTRIN IN PANCREATIC ISLETS OF NORMAL AND GENETICALLY OBESE MICE
Authors: DOCKRAY G. J. , BEST L. , TAYLOR I. L. 
Published: December 2008

SUMMARY
Material with gastrin-like immunoreactivity has been extracted from micro-dissected islets and from antral mucosa of normal and genetically obese mice. The islet and antral extracts cross-reacted with antisera specific for the CO2H-terminal portion of human heptadecapeptide gastrin, but did not cross-react with antisera specific for the NH2-terminal region or with an antiserum specific for the entire, intact, molecule. With the antiserum showing highest cross-reactivity, the concentration of immunoreactive gastrin in normal islet tissue (138 pmol/g, standard human G17-I) was approximately 50% that in obese mouse islets (204 pmol/g) and 2% that in normal antral mucosa (6·1 nmol/g). Following fractionation on Sephadex G-50 the principal forms of gastrin in the islet and antral extracts had similar elution volumes to human heptadecapeptide gastrin, although other, probably smaller, forms of gastrin were also noted in the islet extracts.
AN ANALYSIS OF SPECIFIC STIMULI CAUSING THE RELEASE OF PROLACTIN AND GROWTH HORMONE AT MILKING IN THE GOAT
Authors: HART I. C. , LINZELL J. L. 
Published: December 2008

SUMMARY
Experiments to investigate the relative importance of the tactile, conditioned and possible metabolic components of the milking stimulus on the release of prolactin and growth hormone (GH) from the anterior pituitary of the goat are described. A comparison of the hormonal responses to milking the auto-transplanted mammary gland (i.e. denervated gland) with that obtained by milking the intact mammary gland of the same goat showed that the concentration of prolactin in the plasma increased only after milking the intact gland, whereas in two out of four goats an increase in plasma GH was detected several minutes after milking the transplanted gland. In the intact animal significantly more prolactin (P < 0·01) was released in response to milking both teats for 6 min as compared with that released by milking only one teat for the same time. No significant difference (P > 0·1) was found for GH. Similar quantities of prolactin and GH were released by goats milked when conscious or under anaesthesia. A comparison of the hormonal responses to teat stimulation in the same anaesthetized goats with and without the removal of milk from the mammary gland showed a significant reduction (P < 0·001) in the quantity of prolactin and GH released in the absence of milk removal. The significance of these results is discussed.
PROTEIN BIOSYNTHESIS IN VITRO BY THE PARS INTERMEDIA OF THE MOUSE PITUITARY GLAND
Authors: ISHERWOOD H. , THORNTON V. F. 
Published: December 2008

SUMMARY
During short-term incubations of isolated posterior pituitary glands of the mouse, isotopically labelled amino acids were incorporated into protein by the cells of the pars intermedia. Using labelled leucine, 5–10% of incorporated label was found in a protein (P1), with a molecular weight of about 75000. Protein P1 could be isolated from both fresh and incubated tissue, and was a normal and indeed major, secretory product of the pars intermedia, constituting more than 50% of the protein present.
DECIDUALIZATION AND OVUM-IMPLANTATION IN SPAYED MICE TREATED WITH OESTRIOL
Authors: MARTIN L. 
Published: December 2008

SUMMARY
Single injections of oestriol were partially effective in sensitizing the uterus to a decidual stimulus and inducing ovum-implantation in progesterone-treated spayed mice, whereas two injections (6 h apart) were fully effective. It seems that in the progestational uterus, as in the non-progestational organ, oestriol can induce a full oestrogenic response provided that its level in the target organ is maintained. It is also concluded that ovum-implantation is not triggered by some transient early effect of oestrogen, but requires about 12 h of sustained oestrogen action for its successful completion.
SEASONAL AND CIRCADIAN CHANGES IN THE EPISODIC RELEASE OF FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE AND TESTOSTERONE IN RAMS EXPOSED TO ARTIFICIAL PHOTOPERIODS
Authors: LINCOLN G. A. , PEET M. J. , CUNNINGHAM R. A. 
Published: December 2008

SUMMARY
Six rams of an ancient breed of domesticated sheep (Soay) were subjected to an artificial light régime of alternating periods of long days (16 h light:8 h darkness) and short days (8 h light: 16 h darkness) which induced seasonal development and regression of the testes during a period of 36 weeks. Over 2000 blood samples were taken, and the changes in plasma levels of FSH, LH and testosterone were related to the cycle of testicular activity. During long days plasma levels of gonadotrophins became very low and the testes regressed to about 20% of their maximum size; there was a corresponding reduction in plasma testosterone levels. When the rams were returned to short days reproductive development was again stimulated after 2–3 weeks with a progressive increase in plasma FSH and LH levels and consequent hypertrophy of the testes. It took about 16 weeks of short days for testicular activity to become maximal.
Blood samples collected at hourly intervals for 24 h on ten occasions during the study revealed transitory peaks in plasma FSH and LH levels indicative of episodic release. Changes in gonadotrophin secretion were modulated primarily by alterations in the frequency of episodic release; < 1 spike per 24 h during long days increased to a maximum of 10 spikes/24 h under short daylengths. The peaks of FSH release were of smaller amplitude than those of LH, although during periods of frequent episodic release basal levels of FSH were increased to a greater extent than those of LH.
A circadian rhythm was observed in the plasma levels of FSH, LH and testosterone, which was related to increased gonadotrophin release during the dark phase of the 24 h cycle; changes in blood haematocrit were also observed. The circadian changes appeared to be correlated with the activity cycle of the animals which in turn was dictated by daylight. A possible interrelationship between the circadian cycle and the seasonal cycle is discussed.
IN-VITRO METABOLISM OF [3H]TESTOSTERONE BY SCALP AND BACK SKIN: CONVERSION OF TESTOSTERONE INTO 5α-ANDROSTANE-3β,17β-DIOL
Authors: STEWART MARY ELLEN , POCHI P. E. , STRAUSS J. S. , WOTIZ H. H. , CLARK S. J. 
Published: December 2008

SUMMARY
The in-vitro metabolism of [3H]testosterone by human scalp and back skin was examined for possible differences in enzyme activity in skin from these two areas, both of which contain large sebaceous glands but only one of which, the back, is prone to develop acne. Punch biopsy specimens of skin, obtained from the scalp and back of adult men, were minced and incubated with [3H]testosterone. The metabolic products were diluted with carrier steroids, then separated and measured by thin-layer chromatography and by gas chromatography on an instrument equipped with a splitter. The results showed that of the 5α-reduced metabolites identified, a major one in both the scalp and back skin incubations was 5α-androstane-3β,17β-diol. Formation of the androstanediol was especially pronounced in scalp skin where it accounted for up to 50% of the 5α-reduced metabolites produced. This finding that 5α-androstane-3β,17β-diol is a major product of testosterone metabolism in vitro by human skin containing sebaceous glands, supports the possibility, previously suggested by studies in the rat, that this steroid can stimulate sebum secretion.
METABOLIC CLEARANCE OF RAT PROLACTIN IN THE LACTATING AND NON-LACTATING RAT
Authors: GROSVENOR C. E. , MENA F. , WHITWORTH N. S. 
Published: December 2008

SUMMARY
The metabolic clearance of rat prolactin, assessed by the continuous infusion to equilibrium method, increased from 0·77 to 2·15 ml/min in lactating and from 0·65 to 1·75 ml/min in non-lactating rats as the infusion rate was increased from 100 to 472 ng/min. The clearance rate of rat prolactin did not increase when large doses of ovine prolactin were infused simutaneously with rat prolactin. The clearance rates computed from equilibrium levels of immunoreactive 131I-labelled rat prolactin in plasma were highly correlated with, but were considerably greater than, those computed from unlabelled rat prolactin which was infused simultaneously. In lactating and non-lactating rats, the clearance of each prolactin tested (RP-1, B-1, Nicoll's secreted and 131I-labelled) increased and had stabilized within the 30–35 min of infusion of each new higher dose of the hormone. The ability of the rat to clear quickly greater amounts of prolactin from the circulation as the infusion rate increases implies that plasma prolactin concentrations do not necessarily mirror the rate of prolactin secretion from the pituitary.