bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF CALCIUM AND SODIUM ON VASOPRESSIN RELEASE IN VITRO INDUCED BY A PROLONGED POTASSIUM STIMULATION
Authors: Müller J. R. , Thorn N. A. , Torp-Pedersen C. 
Published: December 2008

ABSTRACT
Groups of isolated hemilobes of rat neurohypophyses were stimulated for 90 min with a 56 mm K+ concentration in the surrounding medium. The rate of release of vasopressin into the medium showed an early maximum followed by a long phase of decline which lasted for most of the stimulation period. When 3 min collection periods were employed, higher secretion rates were obtained than when using 10 min periods. This may be due to a higher rate of removal of vasopressin from the tissue and a lower vasopressin inactivation when 3 min periods are used. When Na+ was replaced by sucrose in the incubation medium for the whole stimulation period, much higher secretion rates than previously reported were obtained (13 % of the total hormone content in the first 30 min period and 21 % for the total 90 min period).
When Na+ was removed from the incubation medium late in the stimulation period, a new high secretion rate was induced, provided that extracellular calcium was present.
When Ca2+ was removed from the medium 3 min after start of the stimulation with 56 mm K+, the secretion rate fell very rapidly. Reintroduction of a normal Ca2+ concentration caused a new marked increase in secretion rate.
These results further stress the importance of extra-cellular calcium for release of vasopressin. In addition they show that a considerable fraction of the vasopressin present in the neurohypophysis can be mobilized during a continued strong stimulation if sodium is omitted from the medium.
ALTERATIONS IN CYCLIC NUCLEOTIDES IN DOGS AFTER TRIIODOTHYRONINE
Authors: Fernandez-Pol J. A. , Hays Marguerite T. 
Published: December 2008

ABSTRACT
The effects of triiodothyronine (T3) on plasma and tissue levels (liver, adipose tissue, muscle) of adenosine 3′,5′-monophosphate (cyclic AMP) and guanosine 3′,5′-monophosphate (cyclic GMP) were determined in Mongrel dogs. Plasma cyclic AMP increased to a mean plateau value 165 % greater than control values in response to a single intravenous injection of T3 (100–200 μg/kg body weight). This treatment resulted in no increase in plasma cyclic GMP. In liver, cyclic AMP concentration decreased 54 %, while cyclic GMP increased 137 %. Adipose tissue cyclic AMP levels decreased in control animals during the experimental procedure. On the other hand, animals given T3 had stable or (in one case) increasing adipose tissue cyclic AMP levels. Hence, T3, actually maintained higher levels than that expected, in comparison to the control. Cyclic GMP levels in adipose tissue were not affected by T3. Cyclic AMP and cyclic GMP were unchanged in muscle. In all cases, a time lag occurred (30–40 min) between administration of T3 and subsequent alterations in cyclic nucleotide levels.
It was concluded that T3 is capable of altering concentrations of cyclic AMP and cyclic GMP in vivo and that cyclic AMP and cyclic GMP patterns of response are completely different. In liver, a converse relation of the two nucleotides is present. These findings are compatible with the hypothesis that some of T3's action may be explained by its effects upon either cyclic AMP or cyclic GMP.
STUDIES ON 17β-HYDROXYSTEROID DEHYDROGENASE IN HUMAN ENDOMETRIUM AND ENDOMETRIAL CARCINOMA
Authors: Pollow K. , Lübbert H. , Boquoi E. , Kreutzer G. , Jeske R. , Pollow B. 
Published: December 2008

ABSTRACT
Specific activity of 17β-hydroxysteroid dehydrogenase (17β-HSD) was measured in subcellular fractions of normal endometrium at different phases of the menstrual cycle, and of endometrial carcinoma at different degrees of differentiation. The purity of fractions was determined by marker enzymes, RNA/DNA ratio or electronmicrographs. Both in normal and neoplastic tissue 17β-HSD activity was located mainly in mitochondria and microsomes. The microsomal enzyme is bound tightly to the membranes of the endoplasmic reticulum. While in normal endometrium specific enzyme activity in subcellular fractions depended on the phase of the cycle, in endometrial carcinoma it depended on the degree of differentiation of the tumours. The highest values of 17β-HSD activity were found in mitochondria and microsomes of early secretory endometrium (factor 10 as compared to proliferative endometrium) and in particulate fractions of well differentiated carcinoma (factor 10 to ⪢ 10 as compared to undifferentiated carcinoma).
TESTOSTERONE 5α-REDUCTION IN THE SKIN OF NORMAL SUBJECTS AND OF PATIENTS WITH ABNORMAL SEX DEVELOPMENT
Authors: Kuttenn Frédérique , Mauvais-Jarvis Pierre 
Published: December 2008

ABSTRACT
Human pubic skin was obtained from normal subjects and patients with abnormal sex differentiation. Skin samples (200 mg) supplemented with NADPH, were incubated for 1 h with labelled testosterone. The conversion of testosterone to dihydrotestosterone1), 3α- and 3β-androstanediol was calculated. This conversion averaged 14.9 ± 3.4 % (se) in 11 normal men and 3.6 ± 1.4 % (se) in 8 normal women. In 4 children as in 4 young hypogonadotrophic hypogonadal men, the conversion rate of testosterone to 5α-reduced metabolites was low (0.8 to 3.5%) and increased at puberty (13.5 to 19.2%). After administration of HCG for 3 months to 1 of the hypogonadal men, it reached 30.2 %. Inversely, the formation of dihydrotestosterone and androstanediols from testosterone was suppressed in 2 men treated with large doses of oestrogen. In 3 subjects with an incomplete form of testicular feminization syndrome, the conversion rate of testosterone to 5α-reduced metabolites was in the normal male range (6.4 to 18.3%), whereas it was low in one case of the complete form of the syndrome (1.5%). In 9 women with idiopathic hirsutism the rate of 5α-reduced metabolites recovered from testosterone was close to that of normal men (13.5 ± 5.5% (se).
From theseresults, it is postulated that in human subjects, there is a good correlation between hair growth in skin from a sexual area and the extent of testosterone 5α-reduction in this tissue. Such an enzymatic activity might be induced by active androgens; this latter hypothesis is in good agreement with the increase of 5α-reduction activity observed at puberty or after treatment of young hypogonadal males.
In addition, it is pointed out that a positive correlation is observed between the 5α-reductase activity present in each skin sample studied and the urinary 3α-androstanediol found for the same individual. This confirms our previous findings suggesting that the determination of urinary 3α-androstanediol might prove of clinical interest in the evaluation of the androgenic status in human subjects.
PEPTIDASES IN THE RAT HYPOTHALAMUS INACTIVATING THYROTROPHIN-RELEASING HORMONE (TRH)
Authors: Griffiths E. C. , Hooper K. C. , Jeffcoate S. L. , White N. 
Published: December 2008

ABSTRACT
Peptidases capable of inactivating thyrotrophin-releasing hormone (TRH) have been demonstrated in the hypothalamus. With the development of a specific radioimmunoassay for TRH, this method was used to further study the enzymes acting on the releasing hormone. Whole hypothalamic homogenates from male and female rats inactivated TRH, with greater peptidase activity being found in the female animals. Separation of the homogenates into particulate (microsomal and mitochondrial) and supernatant (soluble/cytoplasmic) fractions showed approximately the same amounts of enzyme activity in both fractions, while dialysis of the fractions slightly reduced the TRH peptidase activity present, suggesting that a diffusible co-factor might be partially involved in the releasing hormone's degradation. These results confirm the presence of TRH-inactivating peptidases in the rat hypothalamus and suggest that the enzymes may be involved in some way in the mechanisms by which the brain controls thyrotrophin release by the anterior pituitary.
REDUCTION OF CIRCULATING INSULIN LEVELS DURING THE INFUSION OF DIFFERENT PROSTAGLANDINS IN THE RAT
Authors: Saccà L. , Perez G. , Rengo F. , Pascucci I. , Condorelli M. 
Published: December 2008

ABSTRACT
The intravenous infusion of prostaglandin (PG) E1, E2, and A1 into normal rats at a dose of 2 μg/min significantly lowered plasma insulin levels with a tendency to recovery in the post-infusion period. Whereas PGA1 infusion resulted in a moderate but significant hypoglycaemia, the administration of E-series PGs always produced a hyperglycaemic effect. The interference of PGE1 on insulin response to classical insulinogogues (glucagon, aminophylline, and tolbutamide) was also investigated. The results of these experiments demonstrate that PGE1 exerts an inhibitory action on insulin response to all insulin releasing agents investigated. As regards the haemodynamic effects of PGs, PGE1 and PGE2 lowered the arterial blood pressure by about 20%, while PGA1 was almost completely ineffective. On the other hand, the lowering effect of PGE1 on circulating insulin levels remained unchanged in rats treated with reserpine. These findings thus rule out a sympathetic over-activity secondary to the lowered arterial blood pressure as the mechanism of action of PGE1. A possible direct interference with the adrenergic receptor system of the pancreatic islets was also ruled out since the inhibitory effect of PGE1 was not overcome by phentolamine pre-treatment.
EFFECTS OF PROSTAGLANDIN F2α ON OVARIAN BLOOD FLOW AND VASCULAR RESISTANCE IN THE PSEUDOPREGNANT RABBIT
Authors: Janson Per Olof , Albrecht Ivan , Ahrén Kurt 
Published: December 2008

ABSTRACT
In the search for data supporting the hypothesis that the luteolytic effect of prostaglandins (PG) is initiated by a vascular mechanism, some haemodynamic parameters including ovarian blood flow and vascular resistance were measured in pseudopregnant anaesthetized rabbits before and after exogenous administration of PGF2α. The measurements were performed on days 5–10 of pseudopregnancy induced by 500 IU HCG iv.
Infusion of 50 μg/kg PGF2α iv over a one-minute period caused significant falls in cardiac output, heart rate and blood pressure after 1–3 min. Blood pressure and cardiac output were normalized after 16–49 min. Blood flow in the ovarian vein (direct measurements) decreased and returned to initial values parallel to the blood pressure and no change in resistance in the vascular bed drained by the vein was noted. Total ovarian blood flow and resistance, as measured in surgically intact ovaries before and after PG infusion, using 35 or 15 μm 169Yb and 46Sc-labelled microspheres, changed and remained constant respectively, according to the same pattern as in the direct measurements. The distribution of blood flow between the corpora lutea and the interstitial tissue of the ovary measured by 15 μm radioactive microspheres. PGF2α caused an interstitial vasodilation whereas no significant change in luteal vascular resistance was noted. Since luteal blood flow represented a predominant part of total ovarian flow in the type of ovary studied, the interstitial vasodilatation caused only negligible changes in blood flow to the whole ovary. The present study does not support the hypothesis of a PG-induced luteal blood flow reduction preceding luteolysis. The possible significance of the interstitial vasodilatation for luteal function remains to be elucidated.
ENDOCRINE TESTICULAR FUNCTION IN MINK DURING THE FIRST YEAR OF LIFE
Authors: Nieschlag E. , Bieniek H. 
Published: December 2008

ABSTRACT
The endocrine testicular function in mink (Mustela vison) was investigated during the first year of life encompassing puberty, the first mating season and the phase of regression thereafter. The mink, relatively easily accessible as a semi-domesticated animal, was chosen as an example of a mammalian seasonal breeder. In plasma samples from 7 to 17 animals collected on 10 occasions between July and April testosterone and Δ4-androstenedione were determined by simultaneous radioimmunoassay. A steady increase of both androgens from November to early March, when the mating season occurs, and a rapid decline to pre-pubertal levels thereafter was observed. The ratio of testosterone to Δ4-androstenedione was 1:1 from November to April. These findings parallel the known morphological transitions of the testes.
RELATION BETWEEN CIRCULATING LEVELS OF TESTOSTERONE, LH AND FSH IN INTACT AND CASTRATED, ADULT, MALE RATS AFTER TESTOSTERONE ADMINISTRATION
Authors: Verjans H. L. , van der Molen H. J. , Eik-Nes K. B. 
Published: December 2008

ABSTRACT
Serum levels of LH, FSH and testosterone were measured by radioimmunoassay in intact and castrated, adult, male rats after testosterone was administered subcutaneously for seven days in doses ranging from 25 to 200 μg per 100 g body weight per day. Such treatment increased circulating testosterone both in intact and castrated rats, but its effects on serum gonadotrophins were different in these animal groups. All doses of testosterone suppressed serum LH and FSH in the normal rat. In the castrates, treatment with the lowest dose of testosterone resulted in serum LH levels significantly above the high castrate levels, while serum FSH tended to drop. Administration of the highest doses of testosterone did not depress serum LH and FSH in the castrates to those of intact, normal animals, though serum testosterone in these castrates was much higher than in normal, male rats. It is concluded, that the sensitivity of the hypothalamic-pituitary system for daily, subcutaneous testosterone administration during seven days is not the same in the intact and castrated, adult, male rat and that testicular factors different from testosterone may play a role in regulating production and/or secretion of gonadotrophins by the hypophysis in male animals.
IN VIVO UPTAKE AND METABOLISM OF 3H-5α-ANDROSTANE-3α, 17β-DIOL AND OF 3H-5α-ANDROSTANE-3β,17β-DIOL BY HUMAN PROSTATIC HYPERTROPHY
Authors: Horst H.-J. , Dennis M. , Kaufmann J. , Voigt K. D. 
Published: December 2008

ABSTRACT
Tritiated 5α-androstane-3α,17β-diol (3α-diol) and 5α-androstane-3β,17β-diol (3β-diol) respectively were administered to patients with benign prostatic hypertrophy (bph) undergoing prostatectomy. In prostate and skeletal muscle homogenates and in plasma the total radioactivity content as well as the formation of metabolites were measured. Histological examination of each ectomized prostate was performed to evaluate the cellular composition of the tissue.
After 3α-diol injection, a higher uptake of radioactivity in the prostate was obtained than after 3β-diol. Within 30 min the 3α-isomer was very efficiently converted to 5α-DHT, while most of the 3β-isomer remained unchanged. There was, however, also after administration of the 3β-diol a substantial biconversion to 5α-DHT as has been confirmed by recrystallization to constant specific radioactivity. Only after 3β-diol epiandrosterone was detected in small but significant amounts. 3α-diol administration resulted in distinct concentrations of 3β-diol, whereas the conversion of 3β-diol to the 3α-isomer was insignificant. When comparing the histological composition of the prostatic tissue with the accumulation of radioactivity and the formation of metabolites only a weak correlation between glandular structure and radioactivity uptake after 3α-diol administration could be revealed.
EFFECT OF IODIZED OIL ON IODINE CONTENT, THYROGLOBULIN MATURATION AND ON BIOCHEMICAL CONSTITUENTS OF ENDEMIC GOITRE IN BRAZIL
Authors: Medeiros-Neto Geraldo A. , Nicolau William , Takeda Augusta , Cintra A. B. Ulhoa 
Published: December 2008

ABSTRACT
The biochemical and morphological changes in thyroid glands were studied in 5 patients with endemic goitre in the region before and one year after the administration of iodized oil. Each patient received a tracer dose of 125I 3–5 weeks before the biopsy and another tracer of 131I 12 h before surgery. It was observed that:
Iodine deficient goitrous glands had more protein per gram of tissue and that this was corrected by iodination. The goitrous glands exhibited a higher relative proportion of particulate iodoprotein that incorporates more labelled iodine in relation to time of labelling. This abnormal situation is reverted to normal by iodination. A significantly higher proportion of T3 + T4 is synthetized by the glands treated with iodized oil. The increased amount of 127I per gram of tissue is followed by an increased iodination level of thyroglobulin. The ultracentrifugal pattern of proteins observed for iodine deficient glands differed from the iodinated glands, indicating a failure of maturation of thyroglobulin and possibly a greater than normal degree of heterogeneity. The shift in sedimentation pattern was clearly induced by the increased degree of iodination, as shown by the iodized oil injection. The increased cellularity and the higher rate of protein synthesis in the goitrous glands are reverted to normal after the iodized oil injection.
IODINATED PARTICLES IN THE RAT THYROID
Authors: Dang J. , Miquelis R. , Bastiani P. , Simon C. 
Published: December 2008

ABSTRACT
In a previous study (Simon et al. 1971) a procedure for the preparation and separation of iodinated particles was described in the rat. The present paper deals with further investigations on the nature of these particles.
Acid phosphatase and iodine are conjointly sedimentable and display a latency that is unmasked on dilution in a hypo-osmotic medium and under acidification to pH 5.0. These properties together with the sensitivity to Triton X-100 are best accounted for by assuming that iodinated particles of the thyroid gland are lysosomes.
Part of the particulate iodine is soluble in n-butanol (BEI fraction). The existence of this BEI fraction demonstrates that hydrolysis of thyroglobulin occurs within the particles which thus exhibit an acid protease activity. Both the sedimentable iodine pool and acid phosphatase are increased under TSH stimulation and decreased after thyroxine treatment. In addition, the general activity of the iodinated particles is dependent on the daily iodine intake as shown by the variation of their iodine pool, acid phosphatase activity and BEI fraction with the iodine diet. It is concluded that iodinated particles of the thyroid gland are secondary lysosomes which participate in iodine secretion under TSH control.
By in vitro treatment with destabilizing media or after in vivo treatment with thyroxine, iodinated particles exhibit a parallel loss of iodine and acid phosphatase. After a short-term TSH treatment in vivo, their iodine pool is more increased than their acid phosphatase activity. It is concluded that, at least in the normal rat thyroid, iodinated particles are essentially secondary lysosomes; true colloid droplets actually accumulate only after sufficient TSH stimulation.
After ultracentrifugation, 3 main subpopulations are separated for which iodine and acid phosphatase patterns are superimposed. In addition, they all exhibit properties characteristic of secondary lysosomes. Finally, the presence of a fourth sedimentable iodinated fraction with a high turnover rate is postulated.
POTENTIATION OF INSULIN RELEASE BY GLUCOSE IN MAN
Authors: Cerasi Erol 
Published: December 2008

ABSTRACT
Glucose-induced potentiation of glucose-induced insulin release was quantitatively evaluated in 14 non-obese subjects with normal glucose tolerance but decreased insulin response, and in six non-obese patients with mild, adult-onset diabetes, by measuring the insulin responses to two consecutive glucose infusion tests, administered with 40 or 70 min interval. Enhancement of the second insulin response occurred in both groups. In low insulin responders, the dose-response relationship between blood glucose and plasma insulin was flatter and shifted to the right when compared to the control. Pretreatment with glucose increased strikingly the slope of this relationship, the responses now being within the normal range. The enhancement induced by glucose seems to be of multiplicative type. In mildly diabetic subjects, insulin response to glucose infusion was low and sluggish, only a minor initial response being observed. Pretreatment with glucose modified the profile of the insulin response, a clear-cut initial response of greater magnitude being obtained at least in some of the patients. The sensitivity of the islet to the potentiating action of glucose was higher in low insulin responders than in controls, the minimal glucose concentration needed to induce potentiation of the forthcoming response being much lower. The dose-response curve for the relationship between the blood glucose level of the preinfusion period and the percentual enhancement of the insulin response obtained at the second stimulation was, in low insulin responders, higher than and shifted to the left of the curve of the control subjects. In the group of diabetics, sensitivity for potentiation by glucose seemed not different from the controls.
These studies indicate that the ability of glucose to initiate insulin release and its ability to generate time-bound potentiation in the islet correspond to two distinct functions. In the early stages of the diabetic syndrome, only the recognition of glucose as the initiator of an insulinogenic signal is impaired. The pancreatic beta-cell in these subjects seems to recognize normally glucose as the promotor of the potentiation.
FOETAL AND MATERNAL PLASMA LEVELS OF STEROID SULPHATES IN HUMAN PREGNANCY AT TERM
Authors: Laatikainen T. , Peltonen J. 
Published: December 2008

ABSTRACT
Umbilical cord arterial and venous, and maternal peripheral vein blood samples were collected during 20 deliveries after uncomplicated pregnancies. Using a gas chromatographic method, oestriol, oestriol sulphate, progesterone and a number of neutral steroid mono- and disulphates were quantitated in the cord plasma samples and a number of neutral steroid mono- and disulphates in the maternal plasma samples.
The cord venous and arterial plasma levels were compared. Higher concentrations of progesterone and unconjugated oestriol were found in the cord venous plasma. Their mean arteriovenous differences were 40 and 12 μg/100 ml of plasma, respectively. The levels of several steroid monosulphates were higher in cord arterial plasma. The following mean arteriovenous differences were calculated (μg/100 ml): pregnenolone 58, 16α-hydroxypregnenolone 36, 5-pregnene-3β,20α,21-triol 12, dehydroepiandrosterone 42, 16α-hydroxydehydroepiandrosterone + 3β,1 7β-dihydroxy5-androsten-16-one 82, 5-androstene-3β,16α,17β-triol 6, oestriol 29, and for the total pregnanediol mono- and disulphates 20. These results demonstrate that large amounts of steroid monosulphates are secreted by the foetus at term. The levels of individual steroid disulphates examined did not reveal any statistically significant arteriovenous differences. The arteriovenous difference for oestriol sulphate was found to be larger than the venous-arterial difference for unconjugated oestriol indicating that in addition to the unconjugated oestriol of placental origin there are also other precursors of oestriol sulphate.
The correlation between the foetal and maternal plasma levels of the steroid sulphates was investigated. A positive correlation was found, for example, between the cord arterial and maternal plasma levels of 16α-hydroxydehydroepiandrosterone monosulphate and between the maternal and cord venous plasma levels of 5α-pregnane-3α,20α-diol, 5β-pregnane-3α,20α-diol, and 5-androstene-3β,17β-diol disulphates.