bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitory effect of increased photoperiod on wool follicle growth
Authors: Pearson A J , Parry A L , Ashby M G , Choy V J , Wildermoth J E , Craven A J 
Published: December 2004

Abstract
The relationships between circulating prolactin (PRL), wool follicle growth and daylength were investigated in 24 New Zealand Wiltshire ewes housed indoors from September 1989 to May 1991. Twelve control (C) ewes were maintained under natural photoperiod. Two other groups were held in short days (SD; 8 h light:16 h darkness) commencing from the winter solstice (22 June 1990) for either three (group SD3, n=7) or six (group SD6, n=5) months before reversion to natural daylength. Skin was sampled at one- to four-week intervals for histological determination of percentages of growing primary and secondary follicles. Hourly blood samples over 24 h were collected via jugular cannulae from C sheep in March and July and then monthly from all animals until December 1990 for estimation of mean monthly PRL concentrations for each treatment group. Between autumn (March 1990) and winter (July) primary follicle activity (PFA) and secondary follicle activity (SFA) declined in C ewes (PFA: 97 to 43%, SFA: 100 to 57%). Follicle regrowth during July and August in eight C ewes preceded the initial rise in plasma PRL from the winter minimum (1·6 ng/ml). Across the three groups, four instances of decreased follicle activity were observed, closely following or concurrent with increases in plasma PRL concentrations. The resumption of spring growth in four C sheep was temporarily checked by falls in follicle activities during September and October as PRL concentrations began to increase (3·4 to 8·9 ng/ml). Follicle activity also declined in November and December in eight C sheep, coincident with the rapid rise in PRL to a seasonal maximum in late November (165·4 ng/ml). The increase in SD3 follicle activity over spring was not delayed by short days but during October, after release from treatment, PRL concentrations rose (1·8 to 12·0 ng/ml) and follicle activity declined (PFA: 65 to 38%, SFA: 68 to 43%). In SD6 ewes, PRL concentrations were suppressed (2·1 ng/ml) and relatively constant levels of follicle activity (PFA: 73%, SFA: 95%) were maintained throughout short-day treatment. Release of SD6 ewes into summer photoperiod in January 1991 temporarily interrupted follicle growth (PFA: 68 to 17%, SFA: 96 to 19%) and caused out-ofseason shedding in March and April. Contemporary C follicle activities were high (PFA: 95%, SFA: 98%). These data suggest that natural and experimental increases in daylength have a short-term inhibitory effect on growing wool follicles which could be mediated through rising concentrations of plasma prolactin.
Journal of Endocrinology (1996) 148, 157–166
17β-Oestradiol enhances the stimulatory effect of 1,25-dihydroxyvitamin D3 on alkaline phosphatase activity in human osteosarcoma SaOS-2 cells in a differentiation-dependent manner
Authors: Rao L G , Wylie J N , Kung Sutherland M S , Murray T M 
Published: December 2004

Abstract
We tested the effect of osteoblastic differentiation on the interactive effects of 17β-oestradiol (E2) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on alkaline phosphatase activity. As cell models we utilized the more differentiated human osteosarcoma (SaOS) cells that had been cultured for 6 days in medium containing 10 nm dexamethasone (Dex) (SaOS+Dex cells) and the less differentiated cells cultured in the absence of Dex (SaOS−Dex cells). The cells were challenged with 1,25(OH)2D3 in the presence or absence of Dex for 24 h and then with E2 for an additional 24 h. In SaOS−Dex cells, alkaline phosphatase activity remained constant over the 48-h period and was not significantly affected by E2, 1,25(OH)2D3 or 1,25(OH)2D3+E2 treatment. On the other hand, in SaOS+Dex cells, 1,25(OH)2D3 and E2+1,25(OH)2D3 stimulated alkaline phosphatase activity (ANOVA, F= 154·2, P<0·0001) with the maximal response at 48 h (P<0·01). In SaOS+Dex cells, 1,25(OH)2D3 had dose-dependent stimulatory effects which were strongly enhanced by 10 nm E2 (ANOVA, F=46·0, P<0·001). Studies on dose-dependent effects of E2, in the presence or absence of 100 nm 1,25(OH)2D3, revealed that in the presence of 1,25(OH)2D3, the E2 dose-response curve was biphasic in SaOS+Dex cells (ANOVA, F=3·40, P<0·005), with maximum stimulation at 10 nm E2 (P<0·01). The specificity of E2 was verified using the inactive 17α-oestradiol and the oestrogen antagonist, tamoxifen. These data indicate that E2 and 1,25(OH)2D3 have positive interactive effects on alkaline phosphatase activity in human osteoblasts, and suggest that the expression of this interaction is dependent on the stage of differentiation of the cells.
Journal of Endocrinology (1996) 148, 181–187
Characterisation of acyltransferase activity in ovine placental tissue during pregnancy and at the time of labour
Authors: Wong M H , Rice G E 
Published: December 2004

Abstract
Although it is well established that the formation of eicosanoids by ovine intrauterine tissues increases during pregnancy and at the time of labour, the biochemical mechanisms involved remain to be clearly established. In this study, we tested the hypothesis that the gestational and labour-associated increases in eicosanoid formation are associated with a reduction in the activity of the reacylating enzyme, acyl Coenzyme A lysophosphatide acyltransferase (LAT). To evaluate this proposal, in vitro LAT activity was quantified in ovine placenta (cotyledons) obtained during pregnancy (85–147 days of gestation and at the time of labour). Ovine placental LAT increased from 1·81 ± 0·06 nmol/min per mg protein at 85 days of gestation to 2·34 ± 0·10 nmol/min per mg protein at 142 days of gestation (P<0·005, n=15). The apparent Km did not vary significantly between the 85- and 142-day groups. Vmax, however, was significantly greater in the late-gestation group (2·98 ± 0·02 nmol/min per mg protein) than in the mid-gestation group (2·38 ± 0·13 nmol/min per mg protein, P<0·05). In association with labour, placental LAT activity decreased by 16% (1·96 ± 0·13 nmol/min per mg protein) when compared with that observed in tissue obtained from the non-labouring ewe (P<0·01). The data obtained are consistent with the hypothesis that changes in LAT activity in ovine placenta do not contribute to the gestational increase in prostaglandin formation, but a contribution to the labour-associated increase in non-esterified arachidonic acid availability and eicosanoid formation cannot be negated.
Journal of Endocrinology (1996) 148, 241–247
Transcriptional and post-translational regulation of insulin-like growth factor-binding protein-5 in rat articular chondrocytes
Authors: Matsumoto T , Gargosky S E , Oh Y , Rosenfeld R G 
Published: December 2004

Abstract
The aim of this study was to assess the regulation of insulin-like growth factor-binding proteins (IGFBPs) by IGFs in primary cultures of rat articular chondrocytes (RAC). Employing Western ligand blotting, immunoprecipitation and Northern blot analysis, RAC were found to secrete IGFBP-5 (29 kDa) and IGFBP-4 (24 kDa) as the predominant IGFBPs, as well as IGFBP-2 (32–30 kDa) and IGFBP-3 (43–39 kDa) as the minor species. Treatment of cells with IGF-I and IGF-II resulted in a dose-dependent increase of IGFBP-5 and a small increase in IGFBP-4 in conditioned media (CM). Des(1–3) IGF-I and [Gln6, Ala7,Tyr18, Leu19] IGF-II ([QAYL] IGF-II), which bind to the type 1 IGF receptor but not to IGFBPs, also induced IGFBP-5 peptide, although the increase was less than with IGF-I or IGF-II treatment of RAC. [Leu27] IGF-II, which does not bind to the type 1 IGF receptor but binds to IGFBPs, resulted in little induction of IGFBP-5, while [QAYL-Leu27] IGF-II, which has reduced affinity for both the type 1 IGF receptor and IGFBPs, did not increase IGFBP-5. These data suggest that the increase in IGFBP-5 in CM is modulated by both the type 1 IGF receptor and the interaction between IGFs and IGFBPs. Northern blotting analysis showed that IGF-I, IGF-II and des(1–3) IGF-I treatment of RAC increased steady state levels of IGFBP-5 mRNA, suggesting that the IGF-mediated increase in IGFBP-5 is transcriptionally modulated. Interestingly, the increase in IGFBP-5 peptide levels and mRNA were not parallel, suggesting the possibility of post-translational modifications of IGFBP-5, such as those seen with IGFBP-5 protease. IGFBP-5 protease activity was detectable in untreated CM, whereas treatment with IGF-I and IGF-II partially protected IGFBP-5 from proteolysis. In summary, treatment of RAC with IGF-I and IGF-II results in dose-dependent increases in both IGFBP-5 peptide in the CM and mRNA levels. These changes are mediated by interactions via the type 1 IGF receptor as well as IGFBPs, both transcriptionally and post-translationally.
Journal of Endocrinology (1996) 148, 355–369
Why so much oestriol? A comparison of the aromatisation of androstenedione and 16α-hydroxyandrostenedione when incubated alone or together with human placental microsomes
Authors: Othman Y S H , Oakey R E 
Published: December 2004

Abstract
Estimates of the relative abundance of 16α-hydroxy- and 16-deoxyoestrogens in late pregnancy urine lie between 13:1 and 5:1, yet the ratio of the concentrations of the major precursors 16α-hydroxydehydroepiandrosterone sulphate and dehydroepiandrosterone sulphate in cord blood is about 2·5:1. This discrepancy might imply that 16α-hydroxy-C19 steroids are used more efficiently for placental oestrogen biosynthesis than are the 16α-deoxy-C19 steroids.
On testing this hypothesis by incubation of placental microsomes with 16α-hydroxy- and 16-deoxy- precursors together (concentration ratios 128:1 to 1:1), initial rates of oestrogen formation were highest from the 16-deoxy-C19 steroid. Additionally, whilst each substrate appeared to inhibit the aromatisation of the other, the 16-deoxy-C19 steroid was the more potent inhibitor. These findings were supported by an analogous experiment with placental slices.
When each precursor was examined separately with microsomes from 4 placentae, aromatisation of the 16α-hydroxy-C19 steroid (Michaelis constant, (Km) 0·75–1·24 μmol/l, maximum reaction velocity (Vmax) 28–69 pmol product/min/mg protein) was less efficient than that of the 16-deoxy-C19 steroid (Km 0·10–0·15 μmol/l, Vmax 71–145 pmol product/min/mg protein).
To reconcile the disparity between the measured utilisation of precursors in vitro and expectations drawn from precursor availability and urinary excretion rates, sources of urinary 16α-hydroxyoestrogens additional to placental aromatisation need to be considered. Hydroxylation of 16-deoxyoestrogens (the phenolic pathway) appears limited but aromatisation in fetal liver of 16α-hydroxyandrostenedione not utilised by the placenta appears to be worth attention.
Journal of Endocrinology (1996) 148, 399–407
Melanin-concentrating hormone gene-related peptide stimulates ACTH, but not α-MSH, release from the tilapia pituitary
Authors: Gröneveld Diet , Balm Paul H M , Wendelaar Bonga Sjoerd E 
Published: December 2004

ABSTRACT
Tilapia (Oreochromis mossambicus; teleostei) melanin-concentrating hormone gene-related peptide (tMgrp) was tested for tropic actions on adenocorticotropin hormone (ACTH) and α-melanocyte stimulating hormone (α-MSH) producing cells in the tilapia pituitary gland in vitro. Up to 100 μM synthetic tilapia Mgrp (tMgrp) had no effect on α-MSH release from tilapia neurointermediate lobes in a superfusion set up. However, at concentrations above 1 μM, tMgrp concentration dependently stimulated ACTH release from tilapia anterior lobes. This is the first evidence that Mgrp modulates ACTH release from teleost corticotropes, and this might implicate the peptide in the regulation of the pituitary-interrenal axis of fish.
Pituitary lactotrope expresses transforming growth factor β (TGFβ) type II receptor mRNA and protein and contains 125I-TGFβ1 binding sites
Authors: De A , Morgan T E , Speth R C , Boyadjieva N , Sarkar D K 
Published: December 2004

Abstract
Transforming growth factor β1 (TGFβ1) has recently been shown to be produced in the prolactin (PRL)-secreting lactotropes of the pituitary gland. TGFβ1 inhibits lactotropic secretion and proliferation, and the production of TGFβ1 in lactotropes is reduced during lactotropic growth following estrogen treatment in ovariectomized rats. In many estrogen-responsive tissues, TGFβ1 has been shown to exert its effect by binding to TGFβ1 type II receptors (TβR II) at the cell surface. In this study, we sought to ascertain whether TβR II is involved in TGFβ1 action on lactotropes by determining the changes of TβR II mRNA and protein levels and specific 125I-TGFβ1 binding sites on the lactotropes during estrogen-induced proliferation of lactotropes in Fischer 344 rats. Double immunohistochemical procedures were employed to identify immunoreactive TβR II in PRL-reactive cells. The majority of TβR II-reactive cells in the anterior pituitary were observed to be lactotropes. Dual immunohistochemistry and in situ hybridization procedures also indicated that lactotropes were the major cell types containing TβR II mRNA hybrids. Both the levels of immunoreactive TβR II protein and in situ TβR II mRNA hybrids in the pituitary were significantly decreased in ovariectomized rats after 15 days of estrogen treatment. Determination of 125I-TGFβ1 binding sites in lactotropes by double immunohistochemistry and receptor autoradiography also revealed specific binding sites of 125I-TGFβ1 in lactotropes in the anterior pituitary. 125I-TGFβ1 binding in the anterior pituitary was also reduced following estrogen treatment in ovariectomized rats. These data suggest that down-regulation of TβR II may be an important mechanism of estrogen action on lactotropic cell growth and PRL secretion, and further support the notion that TGFβ1 controls lactotropic function by autocrine/paracrine mechanisms.
Journal of Endocrinology (1996) 149, 19–27
Expression of insulin-like growth factors in two bovine oviductal cultures employed for embryo co-culture
Authors: Xia P , Han V K M , Viuff D , Armstrong D T , Watson A J 
Published: December 2004

Abstract
We have investigated the patterns of expression and cellular localization of polypeptides and mRNAs encoding IGF-I and IGF-II in intact bovine oviduct and two bovine oviductal primary cultures (monolayers and vesicles) which are utilized for supporting development in vitro. IGF-I and IGF-II polypeptides were localized by immunocytochemistry in intact oviduct and in both primary cultures for an 8-day culture interval, but IGF-II polypeptide displayed a more restricted distribution in day 8 monolayer cultures. IGF-I and IGF-II mRNAs were localized in both oviductal cell cultures as assessed by in situ hybridization. We were unable to detect IGF-I and IGF-II mRNAs in intact oviduct by in situ hybridization; however, transcripts encoding IGF-I and IGF-II mRNAs were detected in intact oviduct cell preparations and all primary culture samples by reverse transcription-PCR methods. The origin and phenotypic stability of these cultures was assessed by immunostaining with antibodies raised against vimentin (mesenchymal cell marker) and cytokeratin (epithelial cell marker). Over the culture period, the proportion of vimentin-immunoreactive cells increased in the monolayer cultures but remained at a low level in the vesicle cultures which were predominantly composed of cytokeratin-positive cells. The results suggest that oviductal cell co-culture may facilitate early mammalian development, in part, by the establishment of paracrine growth factor circuits.
Journal of Endocrinology (1996) 149, 41–53
GH regulation of the Type 2 IGF receptor in regenerating skeletal muscle of rats
Authors: Kirk S P , Whittle M A , Oldham J M , Dobbie P M , Bass J J 
Published: December 2004

Abstract
GH enhances skeletal muscle growth, and IGF-II peptide is highly expressed during regeneration. We have therefore investigated the effect of GH administration on IGF-II binding and expression in regenerating rat skeletal muscle using the techniques of receptor autoradiography and in situ hybridisation. Notexin, a myotoxin, was injected into the right M. biceps femoris (day 0), causing affected fibres to undergo necrosis followed by rapid regeneration. Animals were administered either GH (200 μg/100 g body weight) or saline vehicle daily. Contralateral muscles were used as regeneration controls. GH administration during regeneration resulted in significant increases in body weight, and damaged and undamaged muscle weights (P<0·001). IGF-II expression, which was examined in regenerating fibres, survivor fibres and undamaged fibres, varied according to tissue type (P< 0·001). Specifically, IGF-II expression in regenerating fibres was elevated relative to control and survivor fibres after day 3 (P<0·05), with a peak on day 9 (P<0·001). GH did not affect IGF-II message levels. 125I-IGF-II binding in regenerating muscle was examined in the same fibre types as well as in connective tissue. 125I-IGF-II binding in regenerating fibres was higher (P<0·001) than in other tissue types on day 5. GH administration increased 125I-IGF-II binding in all damaged muscle tissues on day 5 (P<0·001, regenerating fibres; P<0·01, others). We believe that this shows for the first time an effect of GH on the Type 2 IGF receptor in regenerating skeletal muscle.
Journal of Endocrinology (1996) 149, 81–91
Parathyroid hormone induces superoxide anion burst in the osteoclast: evidence for the direct instantaneous activation of the osteoclast by the hormone
Authors: Datta H K , Rathod H , Manning P , Turnbull Y , McNeil C J 
Published: December 2004

Abstract
We have shown that superoxide anion (O2−) production by the osteoclast can be used as an index of the osteoclast activity since the agents that inhibit and stimulate the osteoclast also diminish and stimulate O2− production respectively. Therefore, we have investigated the mechanism of parathyroid hormone (PTH)-mediated stimulation of osteoclast function in terms of its effect on O2− generation. The determination of O2− generation was carried out by employing cytochrome c immobilised on a surface-modified gold electrode. The basal level of free radical production by the osteoblast-like cells (ROS 17/2·8) was 104-fold lower than by osteoclasts cultured on bone. PTH had no acute effect on free radical production by the osteoblasts. The exposure of the osteoclasts cultured on bone to PTH led to a dramatic and immediate stimulation of O2− generation which was unaffected by the presence of ROS 17/2·8 cells. The osteoclasts cocultured with ROS 17/2·8 cells and exposed to PTH for 3 h were also found to produce greater stimulation of O2− than the osteoclasts exposed to PTH alone. A competitive leukotriene D4 antagonist REV 5901, which also inhibits 5-lipoxygenase, did not block O2− generation by osteoclasts cultured alone or in the presence of osteoblasts. Therefore, we conclude that PTH directly stimulates osteoclasts to produce O2−; this may be the main mode of activation of the osteoclasts, although an osteoblast-mediated effect of the hormone cannot be ruled out.
Journal of Endocrinology (1996) 149, 269–275
Gender differences in the associations between cortisol and insulin in healthy subjects
Authors: Stolk R P , Lamberts S W J , de Jong F H , Pols H A P , Grobbee D E 
Published: December 2004

Abstract
To investigate the role of cortisol in the etiology of insulin resistance in men and women, we examined 218 healthy non-hospitalized elderly, selected from the Rotterdam Study. Free cortisol was assessed by the ratio of fasting serum cortisol over corticosteroid-binding globulin (CBG), and insulin resistance was estimated by the fasting insulin level. CBG was higher in women and decreased with age. In both men and women, the early morning free cortisol level showed no association with age or waist/hip ratio. In men, an inverse association between cortisol and body mass index was observed. In women, higher cortisol levels were associated with increased insulin levels; an increase of 9·7 mU/l insulin per unit cortisol/CBG (s.e. 3·9, P=0·01). The association did not change after adjustment for age, body mass index or waist/hip ratio. The results of this study in elderly subjects suggest that in women cortisol may be implicated in the age-associated insulin resistance.
Journal of Endocrinology (1996) 149, 313–318
IGF-I potentiates interleukin-2 production in human peripheral T cells
Authors: Kooijman R , Rijkers G T , Zegers B J M 
Published: December 2004

Abstract
IGF-I stimulates the proliferation and differentiation of many cell types. In the case of T cells, IGF-I has been described to potentiate mitogen-induced DNA synthesis. We have addressed the working mechanism of IGF-I on T cell proliferation by measuring the effects of IGF-I on various stages of T cell activation. We found that IGF-I augmented the phytohaemagglutinin- and anti-CD3-induced interleukin-2 (IL2) production of human peripheral T cells before they enter the S phase of the cell cycle. Furthermore, the addition of IGF-I did not influence DNA synthesis of IL2-dependent growing T cells.
Journal of Endocrinology (1996) 149, 351–356
Differential effects of malnutrition, bile duct ligation and galactosamine injection in young rats on serum levels and gene expression of IGF-binding proteins
Authors: Holt R I G , Baker A J , Jones J S , Crossey P A , Stone N M , Preedy V R , Miell J P 
Published: December 2004

Abstract
Hepatic gene expression and circulating levels of IGF-binding proteins (IGFBP)-1 to -4 were examined in two rat models of liver disease employing acute hepatitis or chronic structural damage.
The study comprised four groups: group 1 (n=6) was injected intraperitoneally with saline and food was available ad libitum (AL), group 2 (n=6) underwent bile duct ligation (BDL), group 3 (n=6) was injected with 400 mg galactosamine (GAL), group 4 (n=6) was sham-operated and pair-fed to group 2 (PF). All were killed by decapitation at day 7.
Serum IGF-I, by RIA, was significantly (P<0·05) lower in the BDL group (458 ± 37 μg/l) and PF group (451 ±51 μg/l) compared with the AL group (643 ± 77 μg/l) and GAL group (720 ± 67 μg/l). Immunoblotting showed raised IGFBP-2 levels in all groups compared with AL (BDL, 167 ± 14% of AL; GAL, 173 ± 13%; PF, 149 ± 9%). IGFBP-3 was decreased in the GAL (56 ± 11%) and PF groups (66 ± 5%) but increased in the BDL group (154 ± 29%). IGFBP-4 was decreased in the GAL (76 ± 11%) and PF groups (47 ± 5%) but unchanged in the BDL group (90 ± 10%).
By Northern analysis, IGFBP-1 mRNA expression was increased in the GAL (321 ± 51%) and PF groups (263 ± 12%) but reduced in the BDL group (68 ± 8%). IGFBP-2 expression increased in all groups (PF, 836 ± 19%; BDL, 683 ± 121%; GAL, 372 ± 68%) and was highest in the BDL and PF groups. IGFBP-3 expression was reduced in all groups (BDL, 57 ± 16%; GAL, 52 ± 12% PF, 51 ± 13%). IGFBP-4 expression was reduced in the GAL (30 ± 4%) and PF (28 ± 5%) groups but unchanged in the BDL group (76 ± 9%).
Marked changes in gene expression of IGFBPs occurred in both models of liver disease, together with serum changes, which were different from each other and from malnutrition alone.
Journal of Endocrinology (1996) 149, 465–472