bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti-TSH antibodies in Graves' disease and their failure to interact with TSH receptor antibodies
Authors: Ochi Y. , Nagamune T. , Nakajima Y. , Ishida M. , Kajita Y. , Hachiya T. , Ogura H.
Published: December 2008

Abstract. The occasional occurrence in sera of patients with Graves' disease of negative values in the assay for TSH receptor antibodies led to the discovery of endogenous antibodies to TSH. We examined the sera of approximately 2500 patients with Graves' disease. Eight positive sera were found. The IgG in all 8 sera showed higher binding with both bTSH and porcine TSH (pTSH) than with human TSH (hTSH). This means that autoantibodies to TSH in sera from patients with Graves' disease are rare and often directed towards heterologous bovine and porcine TSH. When hTSH levels were determined in sera of hyperthyroid patients with positive antibodies to hTSH, discrepancies in serum hTSH levels were observed when using different assay methods, i.e. hTSH levels were higher with the double-antibody technique, and lower with immunoradiometric assays. Antibodies in these sera showed higher binding to pTSH-α subunit than to -β subunit. The binding of the two pTSH subunits with antibodies could be displaced by intact bTSH. Neither stimulation in Graves' disease nor blocking in primary hypothyroidism of TSH receptor antibodies interfered with the binding of the anti-TSH antibodies to 125I-labelled pTSH, pTSH-α, and pTSH-β. Consequently, using this type of autoantibodies to TSH we were unable to obtain evidence that the TSH receptor antibodies of patients with Graves' disease was an anti-idiotype antibody against anti-TSH antibodies.
The effect of oxytocin administration upon the pulsatile secretion of luteinizing hormone in humans
Authors: Amico Janet A. , Richardson Donald W. , Winters Stephen J.
Published: December 2008

The effect of iv administration of synthetic oxytocin upon the pulsatile pattern of LH secretion was studied in 5 healthy men and 10 healthy women. Five of the women were studied in the follicular phase of a menstrual cycle and the other 5 were studied in the luteal phase of a cycle. Synthetic oxytocin in 0.9% saline or saline alone was administered via continuous iv infusion for 8 h on 2 consecutive days. Infusions were administered using a double-blinded and radomized schedule. The rate of the oxytocin infusion commenced at 1 mU/min and was increased 1 mU/min every 40 min to a final rate of 12 mU/min. The plasma oxytocin concentration during oxytocin infusion ranged from 2–70 fmol/l. Blood for LH determination was sampled every 20 min in the 5 follicular phase women and every 10 min in the 5 men and 5 luteal phase women. The detect algorithm was used to analyze LH pulsatile secretion. Oxytocin infusion was without significant effect on mean LH, number of LH pulses, or area under the LH curve in men or women studied for the period of observation. Thus it is unlikely that increases in plasma oxytocin regulate the pulsatile secretion of LH in humans.
Lymphocytic sodium and potassium pump function in Bartter's syndrome
Authors: Jest P. , Pedersen K. E. , Klitgaard N. A. , Thomsen N. , Kjær E. , Simonsen E. , Jacobsen J. G.
Published: December 2008

Bartter's syndrome is characterized by chronic hypokalaemia, activation of the renin-angiotensin system and normal blood pressure. To investigate whether a generalized disturbance of sodium-potassium pump function might be of pathogenetic importance, lymphocytic sodium-potassium homeostasis was examined in 5 patients suffering from Bartter's syndrome. Two of the patients were treated with potassium chloride supplementation, the others were without medical treatment when studied. All were severely hypokalemic (serum potassium 2.8 ± 0.24 mmol/l, mean ± sem). Lymphocyte sodium and potassium concentration (14.4 ± 0.37 and 94.4 ± 7.7 mmol/l, respectively), ouabain sensitive 22Na-efflux rate constant (2.68 ± 0.25 h −1), and absolute ouabain sensitive efflux rate (38.16 ± 4.2 mmol · I−1 · h−1) did not differ from matched controls. Ouabain binding capacity was 126900 ± 235000 sites/cell in the patients vs 50400 ± 17900 in controls (p <0.05). In conclusion, patients with Bartter's syndrome may have an intrinsic abnormal pump function, characterized by an increased pump density and a low cation turn-over rate per pump unit.
Heterogeneity of human luteinizing hormone. Discrimination between acidic and basic preparations
Authors: van Ginkel L. A. , Loeber J. G.
Published: December 2008

The charge heterogeneity of an LH preparation containing relatively acidic components (LH Type I) was studied. Four biological active components, with pI-values of 5.04, 5.60, 6.06 and 6.57 were detected. A total of four different α-subunits, with pI-values of 4.49, 4.79, 5.16 and 6.02 could be detected after incubation at 37°C. With the exception of the most acidic component all these α-subunits were also present in earlier studied LH Type II preparations. After neuraminidase treatment a strong shift to more basic components was observed, resulting in a population of components similar to the one detected in LH Type II preparations. The β-subunits detected were very different from those observed in Type II preparations. All six components detected had pI-values < 7.5. Upon incubation at 56°C these subunits appeared to be unstable resulting in a shift to more basic pI-values, these pI-values being very similar to those of β-subunits observed before in Type II preparations. After neuraminidase treatment, the pH values of the population of β-subunits became identical to those of the population in LH Type II. From these results it is concluded that the major charge difference between LH Type I and Type II is located in the β-subunits. This difference cannot be explained completely by differences in sialic acid content, but may also be due to heat labile charged groups such as sulphate.
Plasma 18-hydroxycorticosterone and aldosterone responses to angiotensin II and corticotropin in diabetic patients with hyporeninemic and normoreninemic hypoaldosteronism
Authors: Iwasaki Ryoji , Kigoshi Toshikazu , Uchida Kenzo , Morimoto Shinpei
Published: December 2008

To examine the nature of adrenal abnormalities in diabetic patients with hyporeninemic and normoreninemic hypoaldosteronism, responses of plasma 18-hydroxycorticosterone and plasma aldosterone to angiotensin II infusions and ACTH injection were investigated in 8 diabetic patients with hyporeninemic hypoaldosteronism and 9 diabetic patients with normoreninemic hypoaldosteronism compared to 11 control subjects. In both the patients with hyporeninemic and normoreninemic hypoaldosteronism, plasma 18-hydroxycorticosterone and plasma aldosterone were low, whereas plasma cortisol and plasma corticosterone were within normal ranges. Percent increments of plasma 18-hydroxycorticosterone and plasma aldosterone above their baseline levels after angiotensin II infusions were low or somewhat low in the patients with hyporeninemic hypoaldosteronism and low in the patients with normoreninemic hypoaldosteronism. Percent increments of plasma 18-hydroxycorticosterone and plasma aldosterone above their baseline levels after ACTH injection were similar in the three groups. These results suggest that in diabetic patients with isolated hypoaldosteronism, the adrenal abnormality, regardless of whether it is primary or secondary, is mainly due to impaired adrenal responsiveness to angiotensin II and atrophy of the zona glomerulosa.
The role of glucocorticoids in the regulation of thyrotropin
Authors: Brabant Angela , Brabant Georg , Schuermeyer Thomas , Ranft Ulrich , Schmidt Friedrich W. , Hesch Rolf D. , von zur Mühlen Alexander
Published: December 2008

The potentially inhibitory action of endogenous or exogenous synthetic glucocorticoids on TSH secretion was investigated. Pulsatile and circadian TSH and cortisol rhythms were measured in healthy subjects (12 rhythms), but no correlation between the hormones could be detected. Acute stimulation of endogenous cortisol secretion by CRH tests (1 μg/kg of ovine CRH) at 20.00 h in 9 healthy volunteers did not significantly alter the nightly increase in TSH. Chronic elevation of endogenous cortisol serum levels in patients with Cushing's disease revealed a heterogeneous pattern. In 2 patients serum TSH and thyroid hormone levels showed a normal 24-h rhythm, whereas the other 2 patients had low TSH serum levels. Acute treatment of 9 healthy volunteers with 0.5, 1 or 2 mg dexamethasone po at 23.00 h resulted in a significant dose-dependent suppression of mean basal TSH levels 9 h later. Treatment with 30mg of prednisone for 1 week in 7 patients with Crohn's disease did not influence basal TSH. The TSH response to TRH was only temporarily suppressed on day 3, but not on day 7 of treatment. The results suggest that under physiological conditions glucocorticoids have no regulatory influence on pulsatile and circadian TSH secretion.
Assignment of estradiol-17β dehydrogenase and of estrone reductase to cytoplasmic structures of porcine endometrium cells
Authors: Adamski J. , Sierralta W. D. , Jungblut P. W.
Published: December 2008

Homogenates of porcine endometrium contain substantial activity for the dehydrogenation of estradiol-17β but little for estrone reduction. Both activities are associated with cytoplasmic structures. The dehydrogenase is characterized by a pH 7.7 optimum, Km 2.2 × 10−7 mol/l for estradiol and Km 4.4 × 10−5 mol/l for the cosubstrate NAD+. The corresponding figures for the reductase are pH 6.6, Km 1.1 × 10−6 mol/1 for estrone and Km 2.1 × 10−5 mol/l for the cosubstrate NADPH. The (mitochondrial/lysosomal) 17 000 × g particulate fraction contains a 52-fold higher dehydrogenase than reductase activity. The (microsomal) 200000 × g particulate fraction is only 16-fold richer in dehydrogenase. Isopycnic centrifugations of the two fractions in Percoll gradients reveal that estrone reductase and the coequilibrating marker enzyme cytochrome c reductase occur in constant proportions, whereas the dehydrogenase/cytochrome c reductase ratios are different. Both, the kinetic data and the structural assignments speak in favour of individual enzymes catalyzing the dehydrogenation of estradiol and the reduction of estrone. All gradient fractions exhibiting dehydrogenase activity feature small, electrondense vesicles of 0.15–0.20 μm in diameter as a common structural element which might harbour the dehydrogenase.
Prolonged fasting or clonidine can restore the defective growth hormone secretion in old dogs
Authors: Cella Silvano G. , Moiraghi Valerio , Minuto Francesco , Barreca Antonina , Cocchi Daniela , Colonna Vito De Gennaro , Reina Giuseppe , Müller Eugenio E.
Published: December 2008

Age-related changes in GH secretion were studied in the dog. In preliminary experiments, administration of GH-relasing hormone (GHRH-40, 2 μg/kg, iv) or the α2-adrenoceptor agonist clonidine (4 μg/kg, iv) elicited significantly higher plasma GH rises in 3 to 4 years old than in 10 to 14 years old beagle dogs. The pulsatile patterns of GH secretion in both young and old dogs under baseline conditions and after prolonged fasting or clonidine administration were studied. Samples were taken every 10 min from 09.00 to 15.00 h from five young and five old dogs of both sexes. Under baseline conditions, GH peak frequency, total peak area, and integrated GH secretion were significantly lower in old than in young dogs. In old dogs, 5-day complete fasting or 14-day clonidine administration (75 μg/dog, po, twice daily) increased the frequency and amplitude of spontaneous GH bursts, the total peak area, and the integrated GH secretion. After either stimulus, the GH secretory pattern was quantitatively and qualitatively indistinguishable from that of young dogs under baseline conditions. Similarly, the foregoing indices were significantly increased in young dogs by either stimulus, except for the inability of clonidine to affect peak frequency. These data demonstrate that the defective GH secretion in old dogs is not irreversible, since it is normalized when old dogs are exposed to central nervous system-directed stimuli.
Antithyroid antibodies during amiodarone treatment
Authors: Foresti Valeriano , Pepe Roberto , Parisio Elena , Scolari Nadia , Zubani Roberto , Bianco Marina
Published: December 2008

In 44 euthyroid and goitre-free patients, 23 treated with amiodarone (group A) and 21 treated with other antiarrhythmic drugs (group B), antimicrosomal antibodies and antithyroglobulin antibodies were determined before the beginning of treatment and after 7, 15, 30, 60, and 180 days. In group A, none of the patients had antithyroid antibodies before treatment, 1 of 15 patients (6.7%) had antimicrosomal antibodies (titre 1:100) on day 7 only, and 1 of 18 (5.5%) had antithyroglobulin antibodies (titre 1:80) on day 180. In group B, 1 of 21 patients (4.8%) had antimicrosomal antibodies (IgG class) at titre 1:400 before the beginning of treatment, which was negative on day 180, and 2 of 17 (11.8%) had antimicrosomal antibodies (titre 1:100) on day 60 only. None of these patients showed clinical and/or laboratory signs of hyperor hypothyroidism. These data indicated that antithyroid antibodies rarely appear in amiodarone-treated patients and do not differ significantly from patients treated with other antiarrhythmic drugs. The role of autoimmunity and the meaning of antithyroid antibodies in the pathogenesis of amiodarone-induced thyroid dysfunction (mainly of hypothyroidism) in patients without pre-existent thyroid diseases is still unclear.
Mechanisms of increased sensitivity for detection of thyroid stimulating antibodies by use of hypotonic medium
Authors: Kasagi Kanji , Hidaka Akinari , Hatabu Hiroto , Lu Chao , Misaki Takashi , Iida Yasuhiro , Konishi Junji
Published: December 2008

We have attempted to clarify the mechanism whereby the sensitivity to detect thyroid stimulating antibodies by use of cultured thyroid cells is enhanced when sodium chloride is removed from isotonic medium. Preexposure of cultured porcine thyroid cells to 10−4 mol/l cycloheximide increased the subsequent cAMP response to TSab stimulation in isotonic NaCl medium, but not in hypotonic NaCl-free medium. Crude membrane fractions from porcine thyroid tissues were incubated with 6 Graves' IgGs in NaCl or NaCl-free medium at 37°C for 1 h, centrifuged, washed, added [125I]TSH, and incubated for another hour. The result of the 'residual TBII assay' indicated that all 6 IgGs exhibited greater inhibition of [125I]TSH binding to the membranes when pre-incubated under hypotonic than isotonic conditions. When cultured porcine thyroid cells were incubated with 7 TSab samples in NaCl or NaCl-free medium depleted with 3-isobutyl-1-methylxantine at 37°C for 1 h, washed, added the NaCl-free medium containing 3-isobutyl-1-methylxanthine, and incubated for another 2 h, the use of NaCl-free medium during the pre-incubation resulted in greater increase in cAMP elicited by all 7 samples. In summary, 1) an inhibitory mechanism upon adenylate cyclase seems to be involved under isotonic conditions and may require new protein synthesis; 2) the binding of TSH receptor antibodies to the TSH receptor increases when NaCl is removed from isotonic medium, and 3) these factors are considered responsible for the enhanced sensitivity under hypotonic conditions.
Use of ketoconazole in the treatment of a virilizing adrenocortical carcinoma
Authors: Verhelst Johan A. , Druwé Patrick , van Erps Peter , Denis Louis J. , Mahler Charles
Published: December 2008

Ketoconazole, an oral antimycotic agent, is known to have a potent inhibitory effect on adrenal steroid production. It was given at a dose of 1200 mg/day to a 52-year-old female patient with a virilizing adrenocortical carcinoma in order to achieve better metabolic control pre-operatively. Together with a rapid normalisation of hypertension and hyperglycemia, a dramatic fall was noticed in serum and urinary adrenal steroids after a few days. Levels of total testosterone (20 nmol/l), androstenedione (>35 nmol/l) and DHEA-sulphate (>28 nmol/l) fell to normal levels in 6 days. By contrast, levels of 17-OH-progesterone (30 nmol/l) and progesterone (2.45 nmol/l) increased slightly, indicating inhibition af adrenal 17,20-lyase. Cortisol (620 nmol/l at 08.00 h) fell to very low levels (50 nmol/l) on day 6 of the trial. We conclude that ketoconazole is very effective in suppression of adrenal tumoural steroidogenesis and merits consideration in pre-operative use. We warn against dangerous hypoadrenalism which seems to occur earlier in tumoural than in normal adrenal metabolism.
The effects of pulsatile GnRH infusion upon the diurnal variations in serum LH and testosterone in pre-pubertal and pubertal boys
Authors: Gordon Derek , Gray Christina E. , Beastall Graham H. , Thomson John A.
Published: December 2008

The aim of the present study was to determine the effects of exogenous GnRH pulsatile infusions on the diurnal variations of LH and testosterone secretion which occur in late pre-puberty and early puberty. GnRH infusions were administered to 12 short stature males in pre-puberty or early puberty, over 6-day periods. In 6 patients, GnRH doses of 2.5, 7.5 and 15 μg/pulse were used and 24-h profiles of serum LH and testosterone were measured before and at the end of the infusions. In the remaining 6 patients GnRH was administered at a dose of 7.5 μg/pulse and profiles between 21.00 and 06.00 h the following day were determined. Pre-infusion profiles demonstrated nocturnal LH and testosterone rises in all patients. Median pre-infusion serum LH prior to midnight was 2.2 U/l (range 1.0–5.4) rising to 3.7 U/l (range 1.9–10.7) during GnRH administration (p < 0.005). After midnight, median pre-treatment serum LH concentration was 4.3 U/l (range 2.7–7.5) which remained unaltered by GnRH administration (median 4.8 U/l, range 2.9–7.9, p > 0.05). Median pre-therapy serum testosterone before midnight was 0.8 nmol/l (range 0.1−7.1) rising significantly (p < 0.05) to 4.1 nmol/l (range 0.2–8.0). Following therapy, post-midnight median serum testosterone rose from 4.8 (range 0.4–9.4) to 7.0 nmol/l (range 0.5–13.9, p > 0.05). Diurnal variation in LH and testosterone secretion, therefore, is maintained during exogenous GnRH administration to pre-pubertal and pubertal boys. Response to exogenous GnRH pulses may be significantly influenced by endogenous GnRH.
Stimulatory and inhibitory influences of serum from pregnant women on aromatase activity of immature rat Sertoli cells
Authors: Simoni M. , Khan S. A. , De Geyter Ch. , Nieschlag E.
Published: December 2008

Effects of serum from pregnant women on basal and FSH (or cAMP) stimulated aromatase activity of immature rat Sertoli cells in primary culture were studied. Pregnancy serum caused a dose-dependent stimulation of Sertoli cell aromatase activity and the response curves were parallel to those obtained with human FSH. This stimulatory (FSH-like) activity increased progressively during pregnancy, with a sharp drop immediately after delivery. However, the FSH-like bioactivity was not associated with immunoreactive FSH when a specific radioimmunoassay was employed. On the other hand, serum from pregnant women caused a dose-dependent inhibition of FSH and dibutyryl-cAMP-stimulated aromatase activity. These data suggest that human pregnancy serum contains factor(s) which may stimulate basal aromatase activity of Sertoli cells and may inhibit FSH-induced aromatase activity. These factors, most probably of placental origin, may play a role in the regulation of estrogen production during gestation.
Measurement of nocturnal urinary growth hormone values
Authors: Sukegawa Izumi , Hizuka Naomi , Takano Kazue , Asakawa Kumiko , Horikawa Reiko , Hashida Seiichi , Ishikawa Eiji , Mohri Zen-ichi , Murakami Yoshiaki , Shizume Kazuo
Published: December 2008

Nocturnal urinary growth hormone values were measured by a sensitive enzyme immunoassay in normal adults, patients with GH deficiency, patients with Turner's syndrome, normal but short children who had normal plasma GH responses to provocative tests, and patients with acromegaly. The mean nocturnal urinary GH values in patients with acromegaly were significantly greater than those in normal adults (1582.3 ± 579.8 vs 53.5 ± 8.6 pmol/mmol creatinine (± sem); p < 0.05). In the normal but short children and patients with Turner's syndrome, the mean nocturnal urinary GH values were 83.1 ± 5.2 and 79.8 ± 29.5 pmol/mmol creatinine, respectively. In patients with GH deficiency, the nocturnal urinary GH values were undetectable (< 5.3 pmol/mmol creatinine) except in one patient where the value was 6.3 pmol/mmol creatinine. The nocturnal urinary GH values of the patients with GH deficiency were significantly lower than those of the other groups (p < 0.05). In normal but short children, the nocturnal urinary GH values correlated significantly with mean plasma nocturnal GH concentrations (r = 0.76, p < 0.001), and 24-hour urinary GH values (r = 0.84, p < 0.001), respectively. In 4 patients with GH deficiency who had circulating anti-hGH antibody, the urinary GH values were also undectable. These data indicate that nocturnal urinary GH value reflects endogenous GH secretion during collection time, and that measurement of the nocturnal urinary GH values is a useful method for screening of patients with GH deficiency and acromegaly.
Studies on the subcellular mechanisms mediating the negative estradiol effect on GnRH-induced LH-release by rat pituitary cells in culture
Authors: Emons Günter , Frevert Ernst U. , Ortmann Olaf , Fingscheidt Ulrich , Sturm Rita , Kiesel Ludwig , Knuppen Rudolf
Published: December 2008

Cultured pituitary cells from adult female rats were treated for 4 or 24 h in the absence or presence of E2 (10−9 mol/1) with increasing concentrations of the transcription inhibitor actinomycin-D or the translation inhibitor puromycin. During the last 4 h of incubation, LH release was stimulated with 5 × 10−10 mol/1 GnRH. The positive E2 effect observed after 24 h treatment with the steroid was clearly abolished by actinomycin-D at concentrations ≥10−10 mol/1 and by puromycin at concentrations ≥ 10−5 mol/1. These findings indicate that the positive E2 effect on GnRH-induced LH release is fully dependent on intact mRNA and protein synthesis. The negative E2 effect observed after 4 h treatment with the steroid was not affected by actinomycin-D and abolished by puromycin only at concentrations ≥ 10−4 mol/1. Similar results were obtained, when cells had been treated for 4 h with actinomycin-D or puromycin before the 4 h E2 treatment started. Thus, the negative E2 effect seems to be independent of mRNA synthesis and dependent on protein synthesis to a lesser extent than the positive E2 effect. In an attempt to identify positively the subcellular mechanism via which E2 exerts its negative effect, several steps in the GnRH stimulus secretion coupling mechanism were checked whether or not they are modulated by E2. The negative effects of E2 (10−9 mol/1) on LH release induced by GnRH (10−10, 10−9 mol/1) and by the activators of voltage dependent Ca2+ channels K+ (64 mmol/1) or veratridine (3.3 × 10−5 mol/1) were comparable to those of the calcium antagonist verapamil (10−6 mol/1). These findings supported the speculation that E2 might act on the Ca2+ channels. The LH release induced by the Ca2+ ionophores A 23 187 (10 −4 mol/1) or ionomycin (6.6 × 10−5 mol/1), however, was also significantly reduced by 10−9 mol/1 E2, indicating that the steroid modulated a mechanism secondary to the increase of intracellular Ca2+. Also GnRH (10−9, 10−8 mol/1) induced accumulation of [3H]inositol phosphates was not influenced by E2 (10−9 mol/1) treatment, though the steroid exerted a significant negative effect on the LH release by these cells, indicating that phosphatidylinositol-4,5-biphosphate breakdown is not the point of attack for the estrogen. The LH release induced by the activation of protein kinase C with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, 10−7 mol/1) or with the synthetic diacylglycerol 1,2-dioleyl-sn-glycerol (DOG, 5 × 10−5 mol/1, 10−4 mol/1) was significantly reduced by E2 treatment. These findings give rise to the speculation that E2 might exert its negative effect on GnRH-induced LH release in cultured pituitary cells at the level of protein kinase C or a mechanism secondary to the activation of this enzyme.
Effect of estradiol and tamoxifen on GnRH self-priming in perifused rat adenohypophysial cells
Authors: Cover Patricia O. , Buckingham Julia C.
Published: December 2008

Columns of enzymatically dispersed rat pituitary cells have been used to examine the effects of estradiol and the estrogen receptor antagonist, tamoxifen, on the responsiveness of the gonadotropes to repeated challenges with GnRH. Synthetic GnRH stimulated readily the release of LH from the pituitary cells. When challenged repeatedly with the same submaximal dose (8 nmol/1) of the releasing hormone, cells from animals in diestrus 2 or pro-estrus, like those from juvenile rats, showed a marked progressive increase in their sensitivity, but those from rats in estrus or diestrus 1 did not. Adenohypophysial cells removed from adult rats ovariectomized 14 days previously also failed to exhibit sensitization even when estradiol-17β (1 and 10 nmol/1) was included in the perifusion fluid. However, those from ovariectomized rats treated with appropriate doses of the steroid (1.5 μg/day sc for 14 days or 5 μg sc 22 h before decapitation) did. The capacity of pituitary cells from intact rats to exhibit priming on the anticipated day of pro-estrus was unaffected by the administration of the estrogen receptor antagonist, tamoxifen (700 μg/100 g sc on the morning of diestrus 1 and 24 h later). Similarly, addition of tamoxifen (1 μmol/1) to the incubation medium failed to influence the capacity of pituitary cells from juvenile rats to exhibit priming in vitro. The results support the concept that the ability of GnRH to 'prime' the gonadotropes is dependent on estradiol and indicate that the exposure of the hypothalamo-pituitary complex to critical levels of estradiol prior to autopsy is necessary for the gonadotropes to retain their capacity to exhibit priming in vitro.
Studies on the prostaglandin E-2-9-ketoreductase mediated production of prostaglandin F-2α and its metabolism in cultured rabbit luteal cells
Authors: Schlegel Werner , Daniels Dieter
Published: December 2008

Luteal cells were isolated from pseudopregnant rabbits on days 3, 6, 9, 12 and 15 post ovulation. Prostaglandin concentration and the activities of the enzymes prostaglandin E-2-9-ketoreductase and prostaglandin-15-hydroxydehydrogenase were determined. Luteal cells from day 7 and 12 of pseudopregnancy were maintained in culture for 24 h and then exposed to a mixture of [1-14C]PGE2 (70 μmol/l) in the presence or absence of estradiol-17β. After a 24 h incubation period, the culture medium was adjusted to pH 3.5, immediately extracted and analysed for PG. Cultured luteal cells were able to convert exogenously applied PGE2 to PGF2α and to metabolize both PGs. Primary PGs as well as their metabolites 15-keto PGE2, 15-keto PGF2α, 13,14 dihydro15-keto PGE2, and 13,14 dihydro-15-keto PGF2α were detected in the culture medium and in the cells. The addition of estradiol-17β together with PGE2 caused a significant reduction in the PGE2-9-ketoreductase mediated PGF2α synthesis, whereas the metabolism of PGE2 remained unchanged. This inhibitory effect of estradiol-17β was dose-dependent on day 12 of pseudopregnancy. The results demonstrate that isolated rabbit luteal cells are able to synthesize and metabolize the luteolytic factor PGF2α. Whether the inhibitory effect of estradiol-17β may have any physiological relevance has to be examined in further studies.
Bovine neurophysin-II stimulates prolactin release without involvement of dopaminergic prolactin-release inhibiting factor receptor in the estradiol-primed male rat
Authors: Shin S. H. , Obonsawin M. C. , Stirling R.
Published: December 2008

Neurophysins have been considered to be physiologically inert carrier proteins for the neurohypophysial hormones, oxytocin and vasopressin. We have observed that bovine neurophysin-II indirectly stimulates prolactin release in estradiol-primed male rats. The release of prolactin is regulated by a dual hypothalamic control system, the prolactin-release-inhibiting factor and the prolactin-releasing factor. We have tried to clarify whether neurophysin-II is acting through stimulation of prolactin-releasing factor by eliminating the possibility of dopaminergic prolactin release-inhibiting factor release. Male rats were primed with estradiol and functional dopaminergic prolactin release-inhibiting factor receptors were completely blocked by pretreatment with a large dose of pimozide (3 mg/kg), a dopaminergic receptor blocking agent. The neurophysin-II stimulated prolactin release in the rats which did not have any functional dopaminergic prolactin release-inhibiting factor receptors suggesting that neurophysin-II likely initiates a chain of events which eventually stimulates prolactin-releasing factor release since the possibility of involvement of the dopaminergic prolactin release-inhibiting factor system is eliminated. Opioids are known to be one of a chain of events which transmit external stress into a stimulation of prolactin release. Naloxone, a μ-receptor antagonist, was injected 20 min before neurophysin-II administration into rats which were primed with estradiol and pretreated with pimozide (3 mg/kg), but the naloxone administration did not block the prolactin release stimulated by neurophysin-II injection. This result indicates that opioids are not one of the chain of events between initiation of stimulation by neurophysin-II and prolactin release.
Parathyroid hormone potentiates the effect of insulin-like growth factor-I on bone formation
Authors: Spencer E. Martin , Si Erwin C. C. , Liu Chung C. , Howard Guy A.
Published: December 2008

Insulin-like growth factor-I and parathyroid hormone are both known regulators of bone formation. In this study, human recombinant IGF-I and bovine PTH (1–34) and their combination were studied for their effects in vitro on the proliferation of embryonic chick osteoblast-like cells (osteoblasts) and in vivo on bone formation in normal rats. Osteoblasts from 17-day-old chick embryos were cultured in serum-free BGJb medium containing 0.1% bovine albumin. After 2 days, IGF-I and/or PTH were added. Twenty-four hours later [3H]thymidine incorporation into trichloroacetic acid precipitable material was quantified as an index of cell proliferation. This has previously been shown to reflect actual cell division. IGF-I at doses ranging from 0.85 to 13.6 nmol/l caused a dose-dependent increase in [3H]thymidine incorporation into osteoblasts. PTH alone (10 to 1000 pmol/l) had no significant effect. However, when combined with IGF-I, PTH potentiated the mitogenic effect of IGF-I and achieved statistical significance at 30 and 100 pmol/l (p <0.05). This potentiation was also studied in vivo. The right hindlimbs of rats weighing 150 g were infused intra-arterially by an osmotic minipump with graded doses of IGF-I (0.1 to 0.4 nmol/day) and/or PTH (0.27 nmol/day) for 7 days. The rate of trabecular bone apposition (formation) was measured by double tetracycline labelling and compared with the contralateral uninfused limb which acted as the control. Histomorphometric data revaled that neither IGF-I nor PTH alone had a significant effect on trabecular bone apposition rate compared with control limbs. The co-infusion of IGF-I (0.4 nmol/day) and PTH (0.27 nmol/day) resulted in a marked increase in trabecular bone apposition rate. The results of 2 studies were significant at p < 0.01. These data suggest that PTH potentiates the effect of IGF-I on bone formation both in vivo and in vitro.
The role of thyroid hormone autoantibodies in serum transport
Authors: Copping Susan , Byfield Peter G. H.
Published: December 2008

Eleven sera known to contain thyroid hormone autoantibodies were analysed by reverse-flow electrophoresis for the equilibrium distribution of thyroid hormones between these autoantibodies and the three normal binding proteins found in serum. The binding properties of the autoantibodies determined in vitro did not necessarily predict their contribution to transport in serum of T4 and T3. Some could both bind in vitro and transport in serum. Others were able to bind both hormones but transported only one. However, some autoantibodies could be specific, binding and transporting one hormone only. In some sera, the autoantibody was the dominant transport protein having drawn hormone from thyroxine-binding globulin which is normally the most important. The autoantibodies were not saturated even in euthyroid individuals, indicating that they bind hormone reversibly and are a part of an equilibrium system.
Extragonadal effects of luteinizing hormone in mice
Authors: Nomura Kaoru , Puett David W. , Puett David , Shizume Kazuo , Liddle Grant W.
Published: December 2008

LH is composed of isoforms which exhibit microheterogeneity. We recently demonstrated that a particular ovine or porcine LH preparation (G100-fr.3) stimulates kidney growth. This study was conducted to clarify the physiological role of this renotropic activity and other extragonadal effects of the ovine LH preparation in CD-1 mice. Hypophysectomy caused a significantly greater reduction in relative dry kidney weight (i.e. g/100 g body weight) when compared to adrenalectomy, castration, thyroidectomy, and castration plus thyroidectomy. Supplementation with G100-fr.3 in these animals partially restored not only kidney size but also DNA, RNA and protein content. Treatment with standard LH preparations (NIDDKoLH24 and G3-268DA), as well as PRL, GH, FSH and TSH, failed to reverse the renal atrophy induced by hypophysectomy and castration. Administration of testosterone to castrated hypophysectomized mice increased kidney weight and RNA content, but not renal DNA. The relative dry kidney weight increased significantly at the onset of puberty in intact male mice, but not in castrated males or intact female mice. In addition, human CG increased kidney size in hypophysectomized male mice, but not in castrated hypophysectomized animals. These findings indicate that LH isoforms may regulate kidney growth in the male mouse both directly as a renotropin stimulating hyperplasia and indirectly as a gonadotropin via testicular androgen, producing cellular hypertrophy. It was also noted that G100-fr.3 decreased hepatic weight, DNA, RNA and protein, but produced no significant change in the spleen, heart or adrenal glands in castrated-hypophysectomized mice. Such extragonadal effects of G100-fr.3 were also observed in intact female mice. These results suggest that certain LH isoforms may have extragonadal actions involving the kidney and liver.
Adrenal function in HIV infected patients
Authors: Verges B. , Chavanet P. , Desgres J. , Vaillant G. , Waldner A. , Brun J. M. , Putelat R.
Published: December 2008

Since anatomopathological lesions of the adrenal gland have been frequently observed at autopsy in AIDS, we investigated the glucocorticoid function in 63 patients (51 men, 12 women) infected by the human immunodeficiency virus (HIV) in order to determine the incidence and the nature of any adrenocortical abnormalities at various stages of HIV infection. The patients were classified according to the Centers for Disease Control (CDC) recommendations into group II (asymptomatic; N = 13), group III (lymphadenopathy; N = 27) and group IV (clinical manifestations; N = 23). Plasma ACTH and cortisol before and after an exogenous ACTH stimulation test were measured in patients as in 30 agematched controls. Plasma renin activity and plasma aldosterone before and after ACTH stimulation were also measured in 31 patients (group II: 12; group III: 10; group IV: 9). Compared with controls patients from group II–III had higher levels of ACTH (39.11 ± 17.01 vs 29.73 ± 8.53 ng/l; p = 0.003) and basal cortisol (232 ± 91.2 vs 184.3 ± 30.9 μg/l; p = 0.03). No significant differences were noted between group IV patients and controls as to ACTH and basal and stimulated cortisol levels. Among the 63 patients, only one from group IV had a blunted cortisol response after ACTH stimulation test. Plasma renin activity, and basal and stimulated aldosterone levels in the 3 groups of patients were not different from control values. In conclusion: 1. Adrenal insufficiency does not seem very frequent in group IV patients and is likely to be a late complication in AIDS. 2. The increased ACTH and basal cortisol levels found in group II and group III patients argue for an early dysregulation of the adrenocortical axis in HIV infection. The exact physiopathological mechanism is not yet known, but an enhanced CRH production by interleukin 1 and/or a direct role of the HIV envelope glycoprotein (gp 120) may explain the high ACTH level in HIV patients.
Low basal thyrotropin with normal thyroid function in primary hyperparathyroidism
Authors: Gillet Clementine , Bergmann Pierre , Francois Dominique , Body Jean-Jacques , Corvilain Jacques
Published: December 2008

TSH serum levels and thyroid function in 32 patients with primary hyperparathyroidism and hypercalcemia were compared to those of 30 age and sex-matched normal subjects. Serum T3 and T4 concentrations in hyperparathyroidism were not different from normal. However, basal serum TSH concentrations measured with an ultrasensitive immunoradiometric assay were significantly lower than normal (1.09 ± 0.49 vs 2.06 ± 0.85 mU/l, p < 0.001). In hyperparathyroidism, TSH, but not T4 or T3, was negatively correlated with serum calcium, not with iPTH. The increase in TSH (Δ TSH) 30 min after the iv injection of TRH was also significantly blunted in patients with primary hyperparathyroidism; Δ TSH was highly correlated with basal TSH in hypercalcemic patients. The basal TSH concentration was higher and no longer different from normal (1.70 ± 1.2 mU/l) 2 to 12 months after removal of the parathyroid adenoma, when serum calcium was normalized, whereas T3 and T4 did not change. A low basal TSH with normal T4 and low T3 was found in 13 patients with hypercalcemia of malignancy. In these patients, TSH increased after treatment of hypercalcemia with 3-amino-1,hydroxypropylidene-1,1-bisphosphonate, whereas T4 did not change. The results suggest that the set point of pituitary thyroid feedback control could be decreased in chronic hypercalcemia and that hypercalcemia could render the thyroid more sensitive to TSH.
Activity of insulin receptor kinase and glycogen synthase in skeletal muscle from patients with chronic renal failure
Authors: Bak Jens F. , Schmitz Ole , Sørensen Søren S. , Frøkjær Jens , Kjær Torben , Pedersen Oluf
Published: December 2008

To examine subcellular mechanisms behind the pathogenesis of peripheral insulin resistance in chronic uremic patients, insulin receptor function and glycogen synthase activity were studied in biopsies of skeletal muscle obtained during renal transplant surgery in 9 non-diabetic uremic patients. The results were compared with values obtained in an age- and sex-matched group of subjects with normal renal function, undergoing surgery for urological or gynecological diseases. The recovery of solubilized, wheat germ agglutinin-purified insulin receptors from skeletal muscle was increased among the uremic patients: 49.3 ± 6.1 vs 31.4 ± 2.8 fmol/100 mg muscle in healthy controls (p < 0.03). Basal as well as insulin-stimulated kinase activities of the insulin receptors, expressed as phosphorylation of the synthetic peptide poly(Glu-Tyr(4:1)) were similar. In addition, the maximal activity of the glycogen synthase was enhanced in uremic muscle: 26.6 ± 2.8 vs 19.5 ± 1.8 nmol · (mg protein)−1 · min−1 (p < 0.05), whereas the half-maximal activation constant for glucose-6-phosphate was identical in the two groups. Likewise, the muscle glycogen concentrations were similar in the uremic patients and the normal controls. In conclusion, our data suggest that neither impaired insulin receptor function nor a reduced maximal glycogen synthase activity of skeletal muscle are involved in the pathogenesis of the insulin resistance of patients with chronic renal failure.
Long-term effects of radiotherapy for acromegaly on circulating prolactin
Authors: Ciccarelli E. , Corsello S. M. , Plowman P. N. , Jones A. E. , Touzel R. , Rees L. H. , Besser G. M. , Wass J. A. H.
Published: December 2008

In 61 acromegalic patients, serum PRL was assessed (off medical treatment) before and 2 to 12 (mean 6.4) years after external beam radiotherapy. Before radiotherapy elevated PRL levels were present in 22 of 35 males (63%) and 12 of 26 females (46%) and were above 1000 mU/l in 11 males and 5 females. When studied for up to 5 years after radiotherapy, 22 of 23 (96%) patients who had not had surgery and who had normal PRL pre-radiotherapy showed an increased PRL level and this was also seen in 17 of 27 (63%) who had been hyperprolactinaemic initially. In contrast, 10 of 27 patients (37%) who had elevated pre-radiotherapy levels (all greater than 1000 mU/l) had a reduction in PRL values after radiotherapy. In all 11 patients who underwent surgery before radiotherapy, an increase in PRL was seen after radiotherapy. In the 21 patients followed for 10–12 years, the peak PRL value occurred 1–16 years after radiotherapy. After this, a progressive reduction of PRL to normal was seen. Normal levels were reached 4 to 10 years after radiotherapy. No correlation was found between pre-treatment PRL values and final GH values in the whole group, nor between changes in PRL and the development of impaired ACTH or TSH secretion. Thus, different patterns of PRL behaviour suggest that radiotherapy treatment may either produce hyperprolactinemia from mild hypothalamic damage or ablate PRL secreting cells if they were present in the tumour before treatment. These changes do not predict final GH results or the development of hypopituitarism after radiotherapy.
Persistent impairment of the insulin response to glucose both in vivo and in vitro after streptozotocin exposure: Studies with grafted pancreatic islets and islets maintained in culture
Authors: Eizirik Décio L. , Sandler Stellan , Korsgren Olle , Jansson Leif , Andersson Arne
Published: December 2008

The functional responses of the pancreatic B-cells after cytotoxic damage are still largely unknown. Using in vitro models to clarify this issue, we have recently observed a preferential reduction of glucose-stimulated insulin production and release in mouse pancreatic islets maintained in culture after in vitro exposure to streptozotocin. In order to evaluate the relevance of these findings in vivo, two sets of experiments were performed. First, mouse pancreatic islets were exposed in vitro to 2.2 mmol/l streptozotocin or vehicle alone, cultured for 6 days, and finally grafted under the kidney capsule of normoglycemic nude mice. Two weeks after transplantation there was no difference in the total DNA and insulin content between the two groups of islet grafts, but the insulin concentration, as expressed per μg DNA, was decreased by 40% in the streptozotocin-treated islets. The insulin release of the grafts, during perfusion of the graft-bearing kidney in situ with 16.7 mmol/l glucose was diminished in the streptozotocin group, whilst perfusion with 16.7 mmol/l glucose plus 5 mmol/l theophylline was able partially to counteract the reduction in insulin release. In the second set of experiments, NMRI mice were injected iv with 160 mg/kg streptozotocin or vehicle alone, and their islets isolated 15 min after the injections. After 6 days in culture, there was no decrease in DNA, glucagon and somatostatin contents, but the insulin content was decreased by 40% in the streptozotocin exposed islets. These islets also showed a 60% decrease in the insulin response to glucose, which was partly counteracted by incubation with 16.7 mmol/1 glucose plus 5 mmol/l theophylline. These observations suggest that a defective response to glucose, in conjunction with a better response to non-nutrient secretagogues, may be a common property of pancreatic islets following toxin-induced disturbances.
Effects of androgens on bioactivity and immunoreactivity of pituitary FSH in GnRH antagonist-treated male rats
Authors: Sharma Om P. , Khan Shafiq A. , Weinbauer Gerhard F. , Arslan Mohammed , Nieschlag Eberhard
Published: December 2008

The effects of androgens on the bioactivity and molecular composition of pituitary FSH were examined in intact and GnRH antagonist-suppressed male rats. Eight groups of adult Sprague-Dawley rats were subjected to the following treatments: antagonist (75 μg/day by osmotic minipumps; sc), testosterone-filled Silastic implants (3×5 cm, sc), dihydrotestosterone-filled Silastic implants (3×5 cm, sc), E2 benzoate (15 μg/day, sc), and combined administration of antagonist with either steroid for 3 weeks. At the end of the treatment period, pituitaries were dissected out and homogenised. FSH content was determined in the pituitary extracts by an in vitro bioassay and a radioimmunoassay. Individual pituitary extracts from rats treated with vehicle, testosterone and testosterone + antagonist were subjected to isoelectric-focusing on sucrose density gradients performed in the pH range from 3.5 to 7.0. Individual isoelectric-focusing fractions (100-120) were analysed for bioactive and immunoreactive FSH. Treatment with antagonist, E2 or antagonist + E2 caused a significant decrease in pituitary FSH, whereas testosterone and dihydrotesterone alone or in combination with antagonist prevented the decrease in pituitary FSH. The effects of all treatments on both bioactive and immunoreactive FSH were similar. Testosterone treatment not only maintained FSH synthesis but also altered the molecular composition of pituitary FSH. Following treatment with testosterone there was a shift of maximal FSH bioactivity to the more acidic pH range. On the other hand, less bioactivity was recovered than corresponding immunoreactivity in the higher pH region, resulting in significantly reduced ratios of bioactivity to immunoreactivity of FSH. No significant differences were found in the isoelectric-focusing profiles or bioactivity to immunoreactivity ratios of pituitary FSH in animals treated with testosterone alone or in combination with antagonist. The results demonstrate that testosterone not only maintained the synthesis of both bioactive and immunoreactive FSH in male rats, but also influences the molecular composition of pituitary FSH. These effects of testosterone on pituitary FSH appear not to be mediated through hypothalamic GnRH.
The effect of fasting on thyroidal T4-5'monodeiodinating activity in mice
Authors: Wu Sing-yung
Published: December 2008

Complete fasting induces a significant decrease of serum T3 and a fall in TSH in rodents and man. To evaluate the effect of starvation on thyroidal T4 5'monodeiodinating activity, in vitro conversion of T4 to T3 by thyroid and liver homogenate from one to three days fasted mice was compared with homogenates from control mice on animal chow. 5'monodeiodinating activity was significantly lower in thyroid homogenates of fasted mice than in those of chow-fed control [100±5.0 and 92±5.0 pmol T3·(mg protein)−1·h−1 at 48 and 72 h fasting, respectively, vs 132±5.0 pmol T3·(mg protein)−1·h−1 of fed control, p<0.01]. A similar decrease in thyroidal 5'monodeiodinating activity was seen in the liver. The decrease in thyroidal 5'monodeiodinating activity induced by fasting was not reversed by the supplementation of homogenates with the thiol-protecting agent, dithiothreitol (0.2–4.0 mmol/l). Physiological replacement of T4, 0.58 nmol·(100 g)−1·day−1, did not alter the effect of starvation in either the thyroid or liver. TSH (0.02 IU/day) injection, on the other hand, stimulated 5'monodeiodinating activity in homogenates of thyroids from 3-days fasted mice which was no different from TSH-treated fed control. It is postulated that starvation-induced decrease in thyroidal T4 to T3 converting activity may play a role, together with decreased hepatic 5'monodeiodinating activity, in fasting-induced low serum T3 in mice.