bluuebunny/crossref_metadata_2025_split huggingface dataset:
α-Amidated peptides derived from pro-opiomelanocortin in human pituitary tumours
Authors: Fenger M. , Johnsen A. H. 
Published: December 2008

ABSTRACT
Human pituitary tumours, obtained at surgery for Cushing's disease and Nelson's syndrome, were extracted and the content and molecular forms of proopiomelanocortin (POMC)-derived peptides determined by radioimmunoassay, gel chromatography, reversed-phase high-performance liquid chromatography (HPLC) and sequence analysis. In the tumours from patients with Cushing's disease the mean concentrations of amidated peptides relative to the total amount of POMC were as follows: α-MSH, 1·7%; amidated γ-MSH (γ1-MSH), 8·5% and the peptide linking γ-MSH and ACTH in the precursor (hinge peptide or joining peptide) in its amidated form (HP-N), 17·1%. The same relative concentrations in the tumours from patients with Nelson's syndrome were 8·5% (α-MSH), 7·5% (γ1-MSH) and 12·2% (HP-N). More than 95% of the ACTH(1–39) immunoreactivity eluted as synthetic ACTH(1–39) by gel chromatography and HPLC. The remaining ACTH(1–39) immunoreactivity eluted as partly glycosylated high molecular weight forms. All the α-MSH and its glycine-extended precursor ACTH(1–14) were of low molecular weight, mainly non- or mono-acetylated forms, but significant amounts of diacetylated analogues were also present. γ1-MSH and γ2-MSH immunoreactivities eluted as high molecular weight forms and were partly glycosylated. No low molecular weight forms of γ1-MSH or γ2-MSH could be detected in the pituitary tumours. Amidated hinge peptide was mainly of the 30 amino acid form.
In conclusion, all the molecular forms of the amidated peptides detected in tumours from patients with Cushing's disease and Nelson's syndrome were similar to the molecular forms found in the normal human pituitary. The main difference between the tumours and the normal pituitary was the greater amount of peptides produced, particularly α-MSH and γ1-MSH.
J. Endocr. (1988) 118, 329–338
One-step purification of chicken growth hormone from a crude pituitary extract by use of a monoclonal immunoadsorbent
Authors: Berghman L. R. , van Beeumen J. , Decuypere E. , Kühn E. R. , Vandesande F. 
Published: December 2008

ABSTRACT
The immunization of mice with an affinity-purified glycoprotein preparation from chicken pituitary tissue yielded several monoclonal antibodies towards the recently described glycosylated variant of chicken GH. As all these antibodies recognize the classical (non-glycosylated) GH molecule equally well, they provide a suitable tool for the development of both a specific immunoadsorbent and an assay method. This paper deals with the surprising purification power of the immunoadsorbent that was produced with one of the monoclonal antibodies. The resulting preparation was more than 99% pure as assessed by reversed phase high-performance liquid chromatography and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, so that no further purification steps were needed before the determination of the amino acid sequence of the material. The efficiency of the purification protocol as determined by a homologous, monoclonal antibody-based radioimmunoassay was virtually absolute. Moreover, the affinity-purified GH preparation was a mixture representing the multiple molecular forms of pituitary chicken GH, including both oligomeres and glycosylated GH. The purified preparations were finally used to demonstrate the hepatic 5′-monodeiodinase-stimulating activity of GH in the chicken embryo (results not shown), in order to prove that the biological activity of the molecule had not been damaged by elution from the immunoadsorbent.
J. Endocr. (1988) 118, 381–387
Phorbol ester pretreatment attenuates the growth hormone (GH) response to GH-releasing factor in cultured rat pituitary cells
Authors: Ohmura E. , Okada M. , Ohba Y. , Onoda N. , Sano T. , Tsushima T. , Shizume K. 
Published: December 2008

ABSTRACT
The effect of phorbol ester pretreatment on rat (r) GH release induced by GH-releasing factor (GRF) or 8-bromo-cyclic (c)AMP was investigated using rat pituitary cells cultured in monolayers. Pretreatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 3 h significantly suppressed the rGH release induced by GRF, but not that by 8-bromo-cAMP 20 h later; this suppressive effect of TPA was concentration-dependent from 8 to 160 nmol/l, and complete suppression was observed after pretreatment with 80–160 nmol TPA/l. Production of cAMP by pituitary cells stimulated with GRF was similarly attenuated in TPA-pretreated cells. The rGH responsiveness to GRF of these cells was fully recovered on prolonged culture (40 h), suggesting that the inhibitory effect of TPA is reversible.
In contrast, pretreatment with GRF (5 nmol/l) resulted in suppression of the rGH response to subsequent exposure to GRF (5 nmol/l) or 8-bromo-cAMP (10 mmol/l), but not to TPA. These observations suggest that pretreatment with TPA modifies the rGH response to GRF at steps before the formation of cAMP.
J. Endocr. (1988) 118, 423–428
Tumour formation and insulin secretion by clonal RINm5F cells following repeated subcutaneous transplantation in NEDH rats
Authors: Flatt P. R. , DeSilva M. G. , Swanston-Flatt S. K. , Powell C. J. , Marks V. 
Published: December 2008

ABSTRACT
The effects of repeated s.c. transplantation of clonal insulin-secreting RINm5F cells in NEDH rats on tumour morphology, insulin–glucose homeostasis and the function of RINm5F cells re-established in culture were examined after maintenance in vivo for periods of up to 308 days. Transplantation of RINm5F cells for ten consecutive passages consistently produced a single encapsulated vascularized tumour associated with the development in recipient rats of hyperinsulinaemia, hypoglycaemia and eventual neuroglycopenic coma. At the tenth passage, tumour-bearing rats exhibited a markedly enhanced rate of insulinstimulated glucose uptake by 19 days, with evidence of a large and variable insulin response to i.p. glucose. Survival was 22 ± 2 days, and resected RINm5F cell tumours exhibited weak immunostaining for insulin in scattered cells, with strands of fibrous tissue separating clusters of tumour cells many of which had distinct polarity. There was no detectable immunostaining for glucagon, somatostatin or pancreatic polypeptide. The insulin content and insulin secretory output of RINm5F cells re-established in culture after 20, 146, 259 or 308 days propagation in vivo were generally enhanced compared with non-passaged RINm5F cells. The magnitude of the effect was not appreciably affected by the duration of maintenance in vivo, but it was critically dependent upon the subsequent period of culture in vitro. Thus, whereas 2-day cultured RINm5F cells from the eighth tumour passage exhibited a greater than 100–fold increment of insulin content and release, with enhanced secretory responsiveness to leucine, arginine, theophylline, K + (25 mmol/l) or Ca2+ (7·6 mmol/l), RINm5F cells cultured for a further 19 days had almost completely lost the attributes resulting from 259 days of maintenance in vivo. The results indicate substantial enhancement of the functional capabilities of RINm5F cells in vivo, and suggest that the resulting tumours afford a novel model in NEDH rats of responsive trabecular-type insulinomas.
J. Endocr. (1988) 118, 429–437
Solid-phase iodothyronine-5′-deiodinase (5′-D) assays applied in production of monoclonal antibodies against 5′-D
Authors: Boye N. , Frøkiaer H. , Kaltoftt K. , Laurberg P. 
Published: December 2008

ABSTRACT
Characterization of iodothyronine-deiodinating enzymes has been difficult due to loss of enzyme activity during purification. To obtain a new tool for studying these enzymes we investigated the possibility of developing monoclonal antibodies (MAbs) against iodothyronine-5′-deiodinase (5′-D). Two specific and sensitive solid-phase microassays were developed for screening hybridoma supernatants for the presence of antibodies inhibiting rat kidney 5′-D. and antibodies binding to but not inhibiting the enzyme.
BALB/c mice were immunized with a 3-((3-cholamidopropyl) -dimethylammonio) -1- propanesulphonate (CHAPS)-solubilized 5′-D-rich membrane preparation from rat kidney cortical tissue. Spleen cells were fused with NSI-Ag 4/1 mouse myeloma cells by means of polyethylene glycol.
Two hybridoma cell lines (AF5 and BE8) secreting MAbs specifically binding to without inhibiting 5′-D were produced. The AF5 antibody was of the IgG2a subclass and the BE8 antibody of the IgG2b subclass. Binding of one of the antibodies to the enzyme inhibited binding of the other in both an enzyme-linked immunosorbent assay (ELISA) and a specific enzymebinding assay. CHAPS-solubilized kidney microsomal fraction was chromatographed on a Sepharose 6B column. Elution profiles of 5′-D activity and MAb-binding antigens, as measured by ELISA with both AF5 and BE8, were identical.
Monoclonal antibodies should be valuable probes in the further elucidation of the nature of the iodothyronine-deiodinating activity in various tissues.
J. Endocr. (1988) 118, 439–445
Selective release of FSH in lactating rats during the period of follicular atresia induced by the administration of antiserum to LH-releasing hormone
Authors: Taya K. , Sasamoto S. 
Published: December 2008

ABSTRACT
Passive immunoneutralization of LHRH by injecting a caprine antiserum to LHRH (LHRH-AS) in lactating rats nursing two pups on day 5 of lactation resulted in an immediate decline in concentrations of LH in the plasma during the 24-h study period, followed by a gradual increase to control levels 30 h later. Concentrations of oestradiol-17β and inhibin activity in ovarian venous plasma also decreased abruptly in LHRH-AS treated animals and recovered to control levels 36 h later. These changes were correlated with changes in concentrations of LH in the plasma. On the other hand, plasma concentrations of FSH increased abruptly in the LHRH-AS treated animals within 3 h after injection, but the concentrations declined gradually to control levels 48 h later. The ability of follicles to ovulate in response to human chorionic gonadotrophin (hCG) began to decrease within 6 h after treatment with LHRH-AS, and further decreased until 18 h after injection of LHRH-AS, when hCG induced ovulation (with two oocytes) in only one of five animals. A gradual increase in ovulation rate to control levels was noted by 36 h after injection of LHRH-AS. These results indicate that Graafian follicles present at the time of LHRH-AS injection had become atretic and that a new set of follicles had then begun to mature. Selective release of FSH could not be induced by injection of LHRH-AS in ovariectomized animals. Treatment with inhibin (porcine follicular fluid) suppressed the selective release of FSH, whereas treatment with oestradiol-17β had no inhibitory effect on the selective release of FSH.
These findings indicate (1) that tonic secretion of LH is an important factor in normal follicular maturation and maintenance in lactating rats, (2) that selective release of FSH after injection of LHRH-AS is attributed to the removal of a negative influence of inhibin from antral follicles during the period of follicular atresia and (3) that a selective surge of FSH is responsible for initiation of new follicular maturation.
J. Endocr. (1988) 118, 455–464
IDENTIFICATION OF mRNA FOR RELAXIN IN THE ENDOMETRIUM OF THE PREGNANT GUINEA-PIG
Authors: Tashima L. , Greenwood F. C. , Bryant-Greenwood G. D. , Peaker M. 
Published: December 2008

ABSTRACT
The endometrium of late pregnant guinea-pigs was found to contain mRNA for relaxin. Poly(A)+RNA hybridized to 3 2P-labelled porcine relaxin-specific oligonucleotide probes. These probes corresponded to the C-peptide region of the prohormone. There was no hybridization to a 3 2P-labelled probe to the B-chain of porcine relaxin even under conditions of low stringency. The size of the relaxin mRNA was approximately 1.0 kb and similar to that found for relaxin mRNA from the pregnant sow ovary. This is the first study on relaxin mRNA from a uterine source.
Effect of aldrin on spermatogenesis, plasma gonadotrophins and testosterone, and testicular testosterone in the rat
Authors: Chatterjee S. , Ray A. , Ghosh S. , Bhattacharya K. , Pakrashi A. , Deb C. 
Published: December 2008

ABSTRACT
Quantitative evaluation of the different varieties of germ cells at stage VII of the seminiferous epithelium cycle, namely type-A spermatogonia (ASg), preleptotene spermatocytes (pLSc), mid-pachytene spermatocytes (mPSc) and step 7 spermatids (7Sd), along with radioimmunoassay of plasma gonadotrophins (FSH and LH), testosterone and testicular testosterone were performed in Wistar rats following treatment with aldrin (polycyclic chlorinated hydrocarbon insecticide) for approximately one (13 days) or two cycles (26 days) of the seminiferous epithelium.
Extensive degeneration of all varieties of germ cells at stage VII, reduction in the sperm count and significant reductions in plasma concentrations of LH and testosterone were observed following aldrin treatment. The reduction in plasma concentrations of FSH was statistically significant only after treatment for two cycles. The inhibitory effect of aldrin on plasma gonadotrophins, testosterone levels, testicular testosterone content and numbers of 7Sd and ASg was maximum after treatment for two cycles. Administration of human chorionic gonadotrophin along with aldrin treatment for two cycles partially prevented the degeneration of germ cells and enhanced testosterone production.
The results indicate that aldrin may have a direct inhibitory influence on gonadotrophin release, but the possibility of a direct action of the insecticide at the level of the testes is also discussed.
J. Endocr. (1988) 119, 75–81
Comparison of plasma progesterone profiles in cyclic, pregnant, pseudopregnant and hysterectomized pigs between 8 and 27 days after oestrus
Authors: King G. J. , Rajamahendran R. 
Published: December 2008

ABSTRACT
Plasma progesterone concentrations were compared in cyclic (n = 12), pregnant (n =12), oestradiol-induced pseudopregnant (n=12) and hysterectomized gilts (n=10) between days 8 and 27 after oestrus. The results were grouped into periods covering days 8–13, 14–20 and 21–27 and analysed by least-squares analysis of variance. Plasma progesterone concentrations were significantly (P<0·001) higher in hysterectomized compared with other groups between days 8 and 13. Progesterone concentrations declined rapidly after day 14 in cyclic females and gradually in the other groups. Throughout the third and fourth weeks the mean progesterone concentrations for hysterectomized animals were consistently higher than for pseudopregnant animals (P<0·05). The pregnant group means were below but not significantly different from the hysterectomized means in both of the last two periods. The greater progesterone concentrations in hysterectomized gilts indicated that secretion is high without any conceptus-produced or -mediated luteotrophin, and corpora lutea in cyclic, pregnant or pseudopregnant gilts may never reach full secretory potential.
J. Endocr. (1988) 119, 111–116
Ovarian inhibin content in immature female rats following hypophysectomy: control by exogenous gonadotrophins
Authors: Carson R. S. , McMaster J. W. 
Published: December 2008

ABSTRACT
The effect of exogenous ovine gonadotrophins on ovarian inhibin content in hypophysectomized immature female rats was studied to determine which of the pituitary gonadotrophins control ovarian inhibin production in vivo. Inhibin and steroid contents of 27 000 g ovarian supernatants were measured by specific radioimmunoassay. Whereas injection of ovine (o)FSH resulted in dose-dependent increases in ovarian weight, progesterone and oestradiol content above that of control animals injected with diethylstilbestrol alone, injection of oLH was without significant effect. Similarly, ovarian inhibin content was not altered significantly by injection of oLH, but was increased in a dose-dependent manner by injection of oFSH. Concentrations of inhibin in serum were correlated directly with ovarian inhibin content. The results of this study indicate that ovarian inhibin content is increased by injection of oFSH but not oLH. It is likely, therefore, that inhibin production by small antral follicles is controlled by FSH activity alone.
J. Endocr. (1988) 119, 185–189
Effects of 31 kDa bovine inhibin on FSH and LH in rat pituitary cells in vitro: antagonism of gonadotrophin-releasing hormone agonists
Authors: Farnworth P. G. , Robertson D. M. , de Kretser D. M. , Burger H. G. 
Published: December 2008

ABSTRACT
The effects of 31 kDa bovine inhibin on the release of FSH and LH stimulated by gonadotrophin-releasing hormone (GnRH) or its agonist analogue buserelin have been studied using 5-day-old cultures of pituitary cells prepared from adult male Sprague–Dawley rats. Exposure of cultures to increasing concentrations of inhibin for 3 days before and during a 4-h stimulation with GnRH resulted in the progressive suppression of both basal and stimulated gonadotrophin release. At the highest inhibin concentrations FSH release was abolished (inhibin median inhibitory concentration (IC50) = 0·15 U/ml) whereas LH release was suppressed by 75% (IC50 = 0·93 U/ml). To correct for the reduced size of the FSH pool resulting from inhibin pretreatment, the amount of FSH or LH released by an agonist was expressed as a proportion of the total hormone available for release in each case. Following this adjustment, concentrations of inhibin producing maximal effects increased the GnRH median effective concentration for FSH release 4·1-fold and that for LH release 2·2-fold, with inhibin IC50 values of 0·45 and 0·32 U/ml respectively. Inhibin also suppressed the maximum proportion of both FSH and LH that excess GnRH released in 4 h by 36%, with IC50 values of 0·53 and 0·76 U/ml respectively. These effects were not changed by reduction of the inhibin pretreatment period from 3 days to 1 day or by exclusion of inhibin during the stimulation period. After a 3-day pretreatment, inhibin inhibited gonadotrophin release by buserelin less effectively than that by GnRH, but the pattern of antagonism was the same.
The results show that purified bovine inhibin antagonizes the release of both FSH and LH stimulated by either GnRH or buserelin in vitro by reducing the apparent potency of GnRH agonists and by decreasing the proportion of total available gonadotrophin that can be released by an excess of GnRH agonist. Higher concentrations of inhibin are required for these common actions against stimulated release of FSH and LH than for the inhibition of FSH tonic synthesis/basal release, indicating one or more secondary sites of inhibin action in addition to its primary selective action to suppress the constitutive synthesis of FSH.
J. Endocr. (1988) 119, 233–241
Effects of progestins on sexual behaviour in castrated lizards (Cnemidophorus inornatus)
Authors: Lindzey J. , Crews D. 
Published: December 2008

ABSTRACT
In many male vertebrates, androgens stimulate, while progesterone inhibits, sexual behaviour. Testicular androgens also control sexual behaviour in males of the lizard Cnemidophorus inornatus. However, administration of progesterone will reinstate sexual behaviour in castrated animals. Increased doses of progesterone did not result in increased numbers of responders; at all doses tested approximately 36% (n = 45) of animals treated with progesterone responded as reliable courters. A high percentage (60–68%) of progesterone-sensitive individuals maintained their sensitivity over a period of months. A synthetic progestin 17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione with low rates of metabolism and conversion, also stimulated sexual behaviour in castrated C. inornatus. Finally, the synthetic antiprogestin 11β-4-dimethylaminophenyl-17β-hydroxy-17α-1-propinyl-4,9-oestradiene-3-one inhibited the stimulatory effects of progesterone on sexual behaviour but failed to inhibit the stimulatory effects of androgens. These findings indicate an unusual departure from the characteristic pattern of steroid sensitivities of neural centres controlling sexual behaviour.
J. Endocr. (1988) 119, 265–273
Exogenous opioid regulation of the hypothalamic-pituitary-adrenal axis in fetal sheep
Authors: Brooks A. N. , Challis J. R. G. 
Published: December 2008

ABSTRACT
To test the hypothesis that endogenous opioids participate in the regulation of the ontogenic development of the hypothalamic-pituitary-adrenal axis in fetal sheep, we measured changes in immunoreactive (ir) ACTH and cortisol concentrations in response to bolus injections of either the [Met]-enkephalin analogue, [d-Ala2,N-Phe4,Met(0)ol5]-enkephalin (FK 33-824; 25 μg), the opioid antagonist naloxone (1 mg), a combination of both, or saline vehicle, administered to chronically catheterized fetal sheep through late gestation.
There were no effects of either FK 33-824, naloxone or saline on the release of ir-ACTH and cortisol at the earliest stage of gestation studied (days 110–115). By days 125–130, FK 33-824 caused a rapid but short-lived (30 min) increase in plasma ir-ACTH (P <0·05) which was accompanied by a smaller but nonsignificant increase in cortisol. Naloxone given concurrently with FK 33-824 abolished this response, thus providing evidence for a specific effect through opioid receptors. Naloxone given alone was without effect. At days 135–140, FK 33-824 caused a significant increase in ir-ACTH which was of similar duration and magnitude to that which occurred at days 125–130. There was a larger basal variation in plasma concentrations of cortisol than at days, 125–130, and a greater increase in cortisol after FK 33-824, although this did not reach statistical significance. Naloxone again reversed the effects of FK 33-824 but was without effect when given alone.
We conclude that opioid receptors capable of mediating the effects of exogenously administered opioid peptides on the pituitary-adrenal axis are present in fetal sheep by days 123–130. However, we have been unable to demonstrate tonic control of this axis by endogenous opioids, since naloxone is ineffective when given alone.
J. Endocr. (1988) 119, 389–395