bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma growth hormone (GH) responses to single and repetitive subcutaneous administration of GH releasing factor (hpGRF-44) in normal and GH deficient children
Authors: Takano K. , Hizuka N. , Shizume K. , Honda N. , Ling N. C. 
Published: December 2008

Abstract. Synthetic human pancreatic GRF (hpGRF-44) was administered sc to 8 normal children with short stature and 11 patients with GH deficiency. After a dose of 100–200 μg hpGRF-44, mean plasma GH levels reached a peak at 15 min of 27.2 ± 6.4 (± se) ng/ml in normal children. However the responses were variable and peak plasma GH varied from 10.1 to 56.5 ng/ml.
Eight of 11 patients with idiopathic GH deficiency did not respond to sc administration of 100–300 μg hpGRF-44. However, a plasma GH increase of more than 5 ng/ml occurred in 2 patients and to twice the basal level in 1 patient. Their GH values were 14.3, 5.2 and 3.4 ng/ml, respectively. After repetitive administration of hpGRF-44 (200 μg, twice a day) sc for 5 consecutive days, 2 of 8 patients restored their responsiveness, but the remaining patients did not show GH rise in response to both sc and iv bolus administration of hpGRF-44. Repetitive hpGRF-44 administrations for 5 days had no effect on somatomedin-C production.
Biosynthesis and regulation of iodolipids in calf thyroid
Authors: Chazenbalk G. D. , Pisarev M. A. , Juvenal G.J. , de Pisarev D. L. Kleiman , Mercuri H. , De Tomás M. 
Published: December 2008

Abstract. The incorporation of 125I into iodolipids was investigated in calf thyroid slices. Time course studies showed that the iodination of lipid reaches a plateau after 30 min of incubation. A highly significant correlation was found between iodination of lipid and of protein (r = 0.906), suggesting that both reactions may be related. Addition of PTU or MMI caused a significant inhibition of lipid iodination, indicating that a peroxidase could be involved in this reaction. The iodinated lipids are not attached to protein, since they migrated in BEA chromatography and pancreatin digestion of the samples did not modify the percentage radioactivity. The iodolipid fraction observed in BEA chromatography was eluted and analysed by TLC. Iodinated free fatty acids and neutral lipids comprised most of the radioactivity. Although iodolipids are present in every subcellular fraction, the 20000 × g pellet had the greatest proportion of iodinated fatty acids and neutral lipids.
The iodination of lipids is under the control of both TSH and T3. These hormones caused a significant increase at 30–45 min of pulse labelling with 125I. Inhibition of prostaglandin synthesis with indomethacin caused a significant increase in lipid iodination. On the other hand, when phospholipase A2 was blocked by mepacrine, labelling of iodolipid was strongly decreased.
Bombesin inhibits thyrotrophin secretion in rats
Authors: Mitsuma Terunori , Nogimori Tsuyoshi , Chaya Masahiro 
Published: December 2008

Abstract. The effects of peripheral administration of bombesin on thyrotrophin-releasing hormone (TRH) and thvrotrophin (TSH) secretion in rats were studied. Bombesin (200 μg/kg) was injected iv, and the rats were serially decapitated. TRH, TSH and thyroid hormone were measured by radioimmunoassay.
The hypothalamic immunoreactive TRH (ir-TRH) content increased significantly after bombesin injection, whereas plasma concentrations tended to decrease, but not significantly. Plasma TSH levels decreased significantly in a dose-related manner with a nadir at 40 min after the injection. Plasma thyroid hormone levels did not change significantly. Plasma ir-TRH and TSH responses to cold were inhibited by bombesin, but the plasma TSH response to TRH was not affected. In the pimozide- or para-chlorophenylalanine pre-treated group, the inhibitory effect of bombesin on TSH levels was prevented, but not in the l-Dopa- or 5-hydroxytryptophan pre-treated group. These drugs alone had no effect on plasma TSH levels in terms of the dose used. The inactivation of TRH immunoreactivity in plasma or hypothalamus in vitro after bombesin injection did not differ from that of the controls.
These findings suggest that bombesin acts on the hypothalamus to inhibit TRH release, and that its effects are at least partially modified by amines of the central nervous system.
Suppressive effect of prolactin on oestrogen-induced secretion of LH by sequentially perifused rat hypothalamus-pituitary
Authors: Lee Jin-Woo , Miyake Akira , Tasaka Keiichi , Otsuka Shirou , Aono Toshihiro , Kurachi Keiichi 
Published: December 2008

Abstract. The effect of prolactin (Prl) on oestrogeninduced gonadotrophin secretion was examined in vitro in a sequential double chamber perifusion system. As control groups, mediobasal hypothalamus (MBH)-pituitary pairs or pituitaries without the MBHs were perifused with Medium 199. As an experimental group, MBH-pituitary pairs were perifused with Medium 199 containing 1 μg/ml of rat Prl. These groups were stimulated with 10−7m oestradiol-17β (E2) for 30 min, and luteinizing hormone (LH) in the serial fractions of effluent was measured.
In the control group of MBH-pituitary pairs perifused with medium without Prl, secretion of LH began to rise within 30 min after the beginning of stimulation, reached a peak 30 min after the end of stimulation and then remained at a plateau for the rest of the experimental period, whereas in the control group of pituitaries alone no significant response was observed. In the experimental group perifused with medium containing Prl, LH-secretion showed peaks 20 and 80 min after the end of E2-stimulation, respectively, and the first peak was significantly (P < 0.01) less than the level in the control group.
These data demonstrate that Prl at this concentration suppressed the rapid LH release induced by E2. Its site of action is suggested to be at the hypothalamic level, and its possible mechanism of action is discussed.
Insulin-like growth factor I and growth hormone in canine starvation
Authors: Eigenmann J. Eugen , de Bruijne Jan. J. , Froesch E. Rudolf 
Published: December 2008

Abstract. The roles of plasma insulin-like growth factor I (IGF I) and growth hormone (GH) were studied in 7 beagle dogs before and during starvation and during refeeding. IGF I levels significantly decreased from 75.2 ± 5.9 ng/ml at 7 days prior to the start of starvation to 9 ± 1.7 ng/ml at 19 days after the commencement of starvation (mean ± sem; P < 0.0001). During refeeding IGF I significantly rose from 9 ± 1.7 ng/ml to 55.5 ± 7.5 ng/ml within 9 days (mean ± sem; P < 0.002).
During starvation plasma GH levels significantly increased (P < 0.05) and these elevated levels returned to normal during refeeding. The dogs' GH secretory capacity significantly increased during starvation (P = 0.012) and became normal again during refeeding. The following conclusions can be drawn from this study: 1) starvation in the dog leads to a significant and drastic reduction of the circulating levels of IGF I, and 2) starvation in the dog, as in man, leads to increased circulating GH levels and to an increased GH-secretory capacity possibly brought about by a lack of a negative feedback normally exerted by IGF I.
Comparison of in vivo effects of insulin-like growth factors I and II and of growth hormone in hypophysectomized rats
Authors: Schoenle Eugen , Zapf Jürgen , Hauri Christina , Steiner Therese , Froesch E. R. 
Published: December 2008

Abstract. Pure human IGFI (43 and 103 μg/day) and IGFII (131 μg/day) were infused into hypophysectomized rats during 6 days by means of sc implanted minipumps. Their effects on several growth indices were compared with those of various doses of sc infused human growth hormone. Growth hormone infusion produced a dose-dependent rise of endogenous rat IGF from 39 (without growth hormone) to 86 μU equivalents/ml (with 400 mU hGH/day) as determined by a competitive protein binding assay with a human IGF standard. In rats receiving the two doses of IGFI, total serum IGF levels rose to 83 and 99 μU equivalents/ml, respectively, in those receiving the IGFII dose the total serum IGF level rose to 146 μU equivalents/ml. These increases corresponded to steady state levels of 168 and 286 ng/ml of immunoreactive insulin-like growth factor (IR-IGF) I and 320 ng/ml of IR-IGFII. IGFI, but not IGFII led to an increase in body weight similar to that induced by the low doses of hGH (12.5 and 25 mU, respectively). The rise of endogenous rat IGF as well as the infused human IGFI and II caused a widening of the tibial epiphysis and an increase of the [3H]thymidine incorporation into costal cartilage. With respect to these two indices IGF II was clearly less potent that IGF I. When expressed in μU equivalents of the protein binding assay, endogenous rat IGF induced by hGH appeared to be relatively more effective than infused human IGF I or II.
Growth hormone infusion produced a change in the radiochromatographic [125I]IGF binding pattern of hypox rat serum: the gammaglobulin-sized specific IGF binding peak that is characteristic of normal rat serum but lacking in serum of hypophysectomized rats reappeared. Neither infused IGF I nor IGF II had this effect. It may be concluded that the infusion of human IGF I or II in hypophysectomized rats produced qualitatively the same effects on growth indices as a growth hormoneinduced increase of endogenous rat IGF. This supports the idea that IGF I and to some extent also IGF II are able to mediate some of the actions of growth hormone. Other growth hormone effects appear to depend on growth hormone directly.
Different alterations of nuclear triiodothyronine receptor capacity in liver and kidney induced by starvation and triiodothyronine administration
Authors: Nakamura Hirotoshi , Yokota Toshihiko , Imura Hiroo 
Published: December 2008

Abstract. Many studies have shown alterations in the number of nuclear triiodothyronine receptor (NT3R) under pathophysiologic situations. Most of these studies were performed on the rat liver and it is not known whether NT3R in different tissues exhibits an alteration similar to that in the liver.
We compared the change of nuclear receptor capacity for T3 in the liver and kidney during starvation and after T3 injection. Fasting for 72 h decreased maximal binding capacity (Cmax) in the rat liver receptor to 67% of the control, while it did not significantly change Cmax in the kidney. These changes in Cmax were parallel to those of nuclear protein concentrations in both tissues. Daily sc injection of T3 (20 μg/100 g body weight) for 3 days also caused the different alteration of Cmax in the liver and kidney. After T3, hepatic NT3R increased to 182% of the control, but renal NT3R increased only to 136%. Association constants were the same in all groups. These results show that changes of NT3R capacity under some conditions vary in different tissues.
Effects of insulin-like growth factors on chick embryo hepatocytes
Authors: Widmer U. , Schmid Ch. , Zapf J. , Froesch E. R. 
Published: December 2008

Abstract. Biological effects of insulin-like growth factors (IGF) I and II on primary cultures of chick embryo liver cells have been investigated and compared 1) with the biological effect of insulin and 2) with competitive binding of the three hormones to their respective binding sites.
IGF I and II stimulate the incorporation of d[U-14C]-glucose into liver cell glycogen in a time- and dose-dependent manner, but with a 5–10-fold lower potency than insulin: Both IGFs also lead to enhanced incorporation of 5-[3H]uridine and l[U-14C]valine into trichloroacetic acid (TCA) insoluble material and to activation of ornithine decarboxylase activity. Their potency in stimulating RNA synthesis and ornithine decarboxylase activity is comparable to that of insulin. Protein synthesis is maximally stimulated at 3 nm by all three hormones. In the competitive binding studies, IGF I and II are 10-fold less potent than insulin in competing for [125I]insulin binding, but 100-fold more potent than insulin in competing for [125I]IGF I or II binding.
These studies show that IGF I and II stimulate the same metabolic indices as insulin in the chick embryo liver. By comparing these biological effects with competitive binding data it appears that IGFs act on glucose metabolism in the chick embryo liver via the insulin receptor, whereas stimulation of growth indices by IGFs and insulin appears to be mediated by their own specific receptors.
Effects of experimentally-induced diabetes on oestradiol-stimulated changes in the ultrastructure of the rat endometrium
Authors: Frederick G. T. , Kirkland J. L. , Stancel G. M. , Gardner R. M. 
Published: December 2008

Abstract. Alterations in endometrial cell morphology following oestradiol treatment of ovariectomized animals were examined in euglycaemic and streptozotocin-induced diabetic rats. Endometrial morphology was examined 18, 24, 36 and 48 h after oestradiol administration. Nuclei of endometrial cells from saline injected euglycaemic and diabetic rats exhibited pleomorphic nuclei with areas of heterochromatin dispersed throughout the nucleus. Nucleoli were homogenous in appearance and endometrial cells showed no mitotic chromosome function or cell division. The cytoplasm of euglycaemic and diabetic cells contained few mitochondria. The mitochondria that were present contained a uniformly dense matrix and cristae that extended across the mitochondria.
The formation of round to oval shaped nuclei with diffuse euchromatin was observed at 18, 24 and 36 h following oestradiol administration in euglycaemic animals. Alterations in nuclear morphology and the formation of euchromatin were absent or reduced at the same time intervals examined in diabetic animals. Nucleoli in oestradiol-treated euglycaemic animals at 18, 24 and 36 h post-injections became very prominent and displayed easily visible granules and fibrillar material. Comparable changes in nucleolar morphology in oestradiol-treated diabetic rats were absent.
The development of oval to round mitochondria containing short cristae and an electron-lucent matrix became apparent at 18 h post-injection of oestradiol in euglycaemic control animals. Alterations in mitochondrial morphology did not appear in endometrial cells of oestradioltreated diabetic animals at any of the time points examined. At 24 and 36 h post-injection of oestradiol in euglycaemic animals, mitotic figures were observed in mitochondrial cells. Cell division and mitotic figures were not observed in oestradiol-treated diabetic animals. This study demonstrates that a diabetic state in experimental animals profoundly alters the ability of oestradiol to stimulate normal endometrial cell growth.
Age-related changes in prolactin and growth hormone release from pituitary glands in vitro
Authors: Hall T. R. , Harvey S. , Chadwick A. 
Published: December 2008

Abstract. The basal release of prolactin from cockerel anterior pituitary glands in vitro declined between 1 and 7 weeks of age, to a level less than that released by pituitary glands from 18 week old (adult) cockerels and hens. Basal growth hormone (GH) release increased between 1 and 7 weeks of age but had declined in adults to a level similar to that released from 4 weeks old cockerels. The responsiveness of the pituitary gland to hypothalamic stimulation, using hypothalami from 8 week old broiler fowl, was also age-related. Prolactin release was considerably higher from pituitaries of 1 week old cockerels compared to the other age groups. Stimulation of GH release by the hypothalamus was higher from pituitaries of both 1 and 7 week old cockerels compared to the other groups of birds. The increase in release of prolactin following incubation with thyrotrophin releasing hormone (TRH) declined between 1 and 7 weeks, but increased slightly in adult birds, whereas the increase in release of GH following TRH was higher from pituitaries of both 1 and 7 week old cockerels. Hypothalamic prolactin (Prl) releasing activity, measured as the ability of the hypothalamus to stimulate hormone release from 8 week old broiler fowl anterior pituitary glands, declined with the age of the donor cockerels. The hypothalami from adult hens secreted significantly more Prl releasing activity than did adult cockerel hypothalami. The secretion of GH releasing activity decreased markedly with the age of the donor bird.
These results suggest that maturational patterns of hormone secretion in fowl are partly due to changes in autonomous hormone release, to changing patterns of hypothalamic activity and to differences in pituitary responsiveness to provocative stimuli.
Triiodothyronine binding immunoglobulin in a euthyroid man without apparent thyroid disease; its properties and effects on triiodothyronine metabolism
Authors: Isozaki Osamu , Tsushima Toshio , Sato Kanji , Saji Motoyasu , Ohba Yoshito , Emoto Naoya , Sato Yuji , Shizume Kauzo 
Published: December 2008

Abstract. A 54 year old man with markedly elevated serum T3, but without an apparent thyroid disease, was found to have a specific antibody to T3. His serum thyroxine, TBG and TSH were in normal range, but T3-RSU was markedly low. Antibodies to thyroglobulin and microsome were negative. He was judged euthyroid because of a normal basal metabolic rate and a normal thyroidal 123I uptake which was suppressed by T3 adminnistration. When serum was extracted with ethanol prior to assay, serum T3 was found to be in the upper border of normal range. Several experiments revealed the presence of an antibody to T3 in his serum with an affinity constant of 3.3 × 109m−1. The binding capacity of the antibody was 7.6 ng/mg of IgG. The binding of [125I]T3 was almost specific to T3, and potencies of T4 and fT3 in displacing [125I]T3 binding were only 1.0 and 0.3%, respectively, of that of T3. The antibody contained both kappa and lambda chains and was therefore polyclonal.
The T3 metabolic clearance rate, which was determined by disappearance of injected [125I]T3 from serum, was lower in this patient (7.44 I/day) than in normal. The T3-production rate was decreased to 14.9 μg/day, and serum free T3 concentration as well as urinary T3 excretion rate were also reduced. Since both serum total and free T4 concentrations were normal, the supply of T4 to peripheral tissues would be sufficient to keep this patient in a euthyroid state in spite of the anti-T3 antibody.
Steroidogenesis in isolated rat granulosa cells – changes during follicular maturation
Authors: Nordenström Knut , Johanson Carl 
Published: December 2008

Abstract. Steroid release was investigated in granulosa cells isolated from rat ovarian follicles at different maturation stages. Immature rats were treated with 10 IU of pregnant mare's serum gonadotrophin (PMSG) to induce follicular growth and maturation. Granulosa cells were isolated and subsequently incubated for 4 h in the absence or presence of follicle stimulating hormone (FSH), luteinizing hormone (LH) or forskolin. The concentrations of progesterone (P), 20α-dihydroprogesterone (20αDHP), testosterone (T) and oestradiol (E2) in the media were determined by radioimmunoassay. During maturation, basal release of T increased markedly at late dioestrus. At pro-oestrus, concomitant with a sharp rise in E2 and P release, T release returned to previously low levels. Addition of FSH or LH stimulated P release at late dioestrus and pro-oestrus but had no effect on E2 or T levels. Basal 20αDHP levels remained low until a sharp rise at mid pro-oestrus. A stimulatory effect of gonadotrophins on 20αDHP was first seen at this stage. The adenylate cyclase stimulator forskolin resembled FSH in all its effects.
In summary, the present study demonstrates that maturing, but not preovulatory, granulosa cells have an increased capacity to release T during a relatively short period. It is suggested that this T peak could be of great importance for the further progress of follicular maturation.
Gonadotrophins and ovarian steroids in cattle.
Authors: Schallenberger E. 
Published: December 2008

Abstract. Pulsatile LH and FSH release from the pituitary gland of 8 post-partum dairy cows was assessed in series of frequent bleedings (every 20 min for 12 h) performed in about weekly intervals from day 4 through day 32 post partum (pp).
The frequency of short-term secretion of LH increased during individually varying time periods (1.5–5 weeks) from about 1 pulse/4 h to about 1 pulse/1.25 h prior to the re-establishment of luteal function. FSH pulses (average frequency 1 pulse/2 h) were always released concomitantly with LH, but extra FSH pulses occurred in between. Interpulse intervals of LH and FSH (80 ±4 vs 82 ± 7 min) merged prior to the resumption of cyclicity. LH and FSH pulse frequencies remained slightly slower during this first periovulatory period pp than during pro-oestrus and oestrus of regular cycles; also, with one exception, no visible signs of oestrus were expressed. Despite low progesterone concentrations during the first luteal phase there was strong negative feedback mainly on LH, thus considerably prolonging the intervals between consecutive LH pulses (up to 620 min) whereas FSH release remained much faster (up to 270 min interpulse interval). LH interpulse intervals tended to be longer during short compared to normal length cycles post partum (420 ± 107 vs 285 ± 51 min) in the presence of only slightly altered FSH release (154 ± 37 vs 107 ± 7 min).
As the pituitary gland is able to secrete already early pp frequent pulsatile FSH contrary to LH, a selective suppression of LH including a maximal sensitivity to the negative feedback action even of low ovarian steroid concentrations and a lack of the positive feedback mechanism during an initial period have to be postulated. The ovarian-uterine unit seems to play a major role in the timing of the resumption of unimpaired reproductive functions post-partum.
Gonadotrophins and ovarian steroids in cattle.
Authors: Schallenberger E. , Prokopp S. 
Published: December 2008

Abstract. The re-establishment of the positive feedback action of oestradiol-17β on both gonadotrophins was assessed in 20 dairy cows receiving three challenges once every 20 days from parturition through day 55 post partum (pp). One mg oestradiol-17β-benzoate dissolved in 5 ml oil was given im every 5 days to groups of 5 cows each. Blood was collected from the jugular vein every 3 – 12 h from 2 days before until 2 days after the injection.
No effect of oestradiol-17β on the LH release was exerted at parturition or day 5 pp. A stimulation of LH release started to occur in the majority of cows by day 10 pp. Two types of preovulatory like surges could be elicited: low magnitude LH releases lacking any concomitant FSH increase and parallel high magnitude LH and FSH surges. No cow expressed heat when exhibiting a weak LH surge before day 30 pp and only 30% thereafter. All cows showed oestrus when exhibiting parallel high magnitude LH/FSH surges after day 20 pp but only 40% on days 10 and 15 pp. Progesterone concentrations >0.5 ng/ml prevented the positive feedback action of oestradiol on LH and FSH. An initial negative feedback on FSH was exerted throughout the entire post-partum period comprising the luteal phase.
We conclude from these results that a certain minimum threshold frequency of endogenous LH secretion is necessary to allow oestradiol-17β to evoke its unimpaired stimulatory feedback action after an initial period of pituitary refractoriness during the early puerperal anoestrus and acyclic period.