bluuebunny/crossref_metadata_2025 huggingface dataset:
LIGAND-BINDING CHARACTERISTICS OF RAT TESTIS RECEPTORS FOR LUTEINIZING HORMONE
Authors: Esfahani Mojtaba , Schlamowitz Max , Cronquist Jacqueline , Ward Darrell N.
Published: December 2008

Ligand-binding activity of rat testis homogenate increases during storage for 24 h at 4°C, and rapidly deteriorates after 48 h at the same temperature. Inhibition of cellular proteases with phenylmethanesulphonylfluoride (PMSF) preserves the activity for 7 days, and, lyophilized preparations of the tissue homogenate retain their ligand-binding activity for prolonged periods of time during storage at 4°C. The rate of increase in ligand-binding capacity is temperature-dependent. Enhancement of activity is also noted in the purified membrane fraction and appears to be due to unmasking of receptor molecules in the membrane. Even in the presence of PMSF, there is a rapid and irreversible loss of ligand-binding activity when either fresh or reconstituted freeze-dried receptor preparations are pre-incubated at 37°C, although in the former case this is preceeded by a brief period of activation. The destabilization of the reconstituted lyophilized preparation at 37°C is induced by the dehydration step in the freeze-drying process and not by freezing alone. It is therefore unlikely that the rapid inactivation at 37°C is enzymatically induced; rather it is due to destabilization of membrane architecture and/or receptor accessibility. The inherent inaccuracies of measurements of kinetic parameters and assessments of the number of receptor sites in such unstable systems by Scatchard plots of binding data are pointed out.

Evidence is presented which indicates that in the presence of luteinizing hormone the spontaneous inactivation of receptors is inhibited and that there is an apparent "conservation" of receptor sites. A mechanism whereby this is accomplished is proposed, on the basis of the kinetics of inactivation.
SECRETIN-INDUCED INSULIN RESPONSE
Authors: Enk B. , Lund B. , Schmidt A. , Deckert T.
Published: December 2008

Intravenous injection of the gastro-intestinal hormone secretin elicits an increase in the insulin concentration in the cubital vein.

In 10 normal weight non-diabetics and 10 obese non-diabetics the latter group gave a hypernormal insulin response.

By the simultaneous determination of the insulin concentration in the cubital and portal veins and also by an investigation of 2 pancreatectomized patients, it was demonstrated that an increase in the cubital insulin concentration following intravenous injection of secretin was due to an altered secretion from the pancreas and not to an altered elimination of insulin.
PLASMA INSULIN AND GROWTH HORMONE CONCENTRATIONS IN PREGNANT SHEEP II:
Authors: Blom Anne Kristine , Hove Knut , Nedkvitne Jon J.
Published: December 2008

The pregnant ewe compensates the reduced carbohydrate availability in late pregnancy by increased fat combustion. The purpose of the present study was to examine the adaptation of plasma growth hormone (GH) and insulin levels to this change in energy substrate metabolism. Two groups of ewes were bled in the post-absorptive state at different stages of pregnancy. One group (7 animals) was fed adequately throughout pregnancy, while the other received a maintenance ration for non-pregnant sheep (28 animals).

Plasma GH increased from averages from 2–3 to 8–14 ng/ml during the last month before lambing. Shearing of the wool combined with a cold stress resulted in a clearly detectable peak in plasma GH in the underfed sheep. No significant difference in plasma GH attributable to differences in diet could be detected in late pregnancy.

Plasma insulin decreased steadily the last 5 weeks towards lambing, most in mothers with 3 lambs. Plasma free fatty acid levels (FFA) increased the last 2 months of pregnancy, most in the underfed sheep. GH and FFA were positively correlated (r = 0.50 and 0.30 in the two groups).

It is concluded that the adaptation of the maternal metabolism to reduced carbohydrate - and eventually energy-availability in late pregnancy included lowering of insulin and enhancement of plasma GH levels. These adaptations were detectable under the present conditions the last 5–6 weeks before term.
STUDIES ON THE PATTERN OF CIRCULATING STEROIDS IN THE NORMAL MENSTRUAL CYCLE
Authors: Aedo A.-R. , Landgren B.-M. , Cekan Z. , Diczfalusy E.
Published: December 2008

Plasma levels of 20α-dihydroprogesterone, 17-hydroxyprogesterone and 17-hydroxypregnenolone were assayed daily in 15 normally menstruating women during a complete menstrual cycle. In order to ascertain the normalcy of the cycles studied, LH, progesterone and oestradiol were also determined daily.

The pattern of 20α-dihydroprogesterone was very similar to that of progesterone. The levels found during the proliferative phase (around 240 pg/ml) increased significantly on the day of the LH-surge and reached values of approximately 3.7 ng/ml at the peak period of luteal activity.

The plasma levels of 17-hydroxyprogesterone in the proliferative phase were around 380 pg/ml. The first significant increase occurred one day before the LH-surge and was followed by a sharp peak (approximately 1.5 ng/ml) which coincided with the LH peak. A significant decrease occurred after this first peak, which reached a nadir two days after the LH-surge. This was followed by a second rise with a rather broad peak (about 1.8 ng/ml) around the 5th to 7th days after the LH-surge.

The levels of 17-hydroxypregnenolone did not show any cyclic variation: from all figures a geometric mean value of 1.62 ng/ml was calculated with tolerance limits at 0.241 and 10.8 ng/ml.

Individual day-to-day changes in steroid levels were assessed with regard to their potential for the early identification of the day of the LH-surge. A 17-hydroxyprogesterone value of 1.0 ng/ml, or more, was seen for the first time in the cycle on the day of the LH peak in 13 cycles and a progesterone + 17-hydroxyprogesterone level of at least 1.8 ng/ml in 14 of the 15 cycles studied. These data seem to warrant a study of the predictive value of progesterone and 17-hydroxyprogesterone assays in a much larger population.
STUDIES ON THE CONVERSION OF OESTRADIOL LINKED TO A CYTOSTATIC AGENT (ESTRACYT®) IN VARIOUS RAT TISSUES
Authors: Høisaeter Per Aage
Published: December 2008

Estracyt®, a compound of nitrogen-mustard linked to oestradiol phosphate, is used in the treatment of human prostatic cancer. The metabolism of this compound has been studied in different tissues of the rat both in vivo and in vitro.

The phosphate group in position 17 of the oestradiol moiety is rapidly split off from the compound. An oestrone-cytostatic compound was extractable from the liver half an hour after the injection of Estracyt®. In addition the in vitro results showed that only the liver was able to convert the oestradiol-cytostatic compound to an oestrone-cytostatic one. When animals were killed 24 h after a 3-day period of Estracyt® treatment, the dominating metabolite in the ventral prostate was an oestrone-cytostatic compound, but traces of free oestrone could also be demonstrated. No such compound, however, was found in liver, diaphragm or blood at this time.

It is concluded that in vivo an oestrone-cytostatic compound seems to be preferentially retained in the ventral prostate after Estracyt® injection whilst the metabolic conversion of the oestradiol-cytostatic compound into an oestrone-cytostatic one possibly occurs in the liver.
ISOLATION OF CANINE PROLACTIN BY POLYACRYLAMIDE GEL ELECTROPHORESIS
Authors: Jones G. E. , Brownstone A. D. , Boyns A. R.
Published: December 2008

The electrophoretic mobility of prolactin obtained from canine pituitary extract was studied with the aid of polyacrylamide disc electrophoresis. Using a preparative gel electrophoretic system the immunoreactive material was purified on a quantitative scale which was then used to develop a homologous radioimmunoassay for canine prolactin.

The radioimmunoassay system was able to detect prolactin in the plasma of dogs after the administration of agents which would be expected to affect prolactin secretion.
AUGMENTED SECRETION OF TSH IN RESPONSE TO TRH AFTER PRE-TREATMENT WITH DEXAMETHASONE FOR SIX DAYS IN RATS
Authors: Ranta Tapio
Published: December 2008

Serum TSH and corticosterone concentrations were measured in rats given TRH or exposed to short-term cold, as well as in intact rats, after pretreatment with dexamethasone for six days at two different dose levels (25 and 250 μg/100 g body weight). Both doses increased the secretion of TSH in response to TRH whereas cold-induced TSH secretion was not modified by pre-treatment with dexamethasone. In intact rats serum TSH levels did not differ significantly from controls. In all experiments the steroid blocked ACTH secretion. It was also found that administration of TRH produced a rise in serum corticosterone concentrations.

Our results support the view that dexamethasone given for six days facilitates TRH stimulation of the pituitary whilst simultaneously inhibiting the secretion of TRH in response to cold.
CHANGES IN PLASMA RENIN ACTIVITY AND PLASMA ALDOSTERONE IN THE INDUCED PARALYTIC ATTACK OF THYROTOXIC PERIODIC PARALYSIS
Authors: Takeda Ryoyu , Morimoto Shinpei , Uchida Kenzo , Miyamori Isamu
Published: December 2008

Changes in serum electrolytes, haematocrit, plasma renin activity and plasma aldosterone induced by glucose and insulin (GI) infusion were serially investigated in seven patients with periodic thyrotoxic paralysis. An attack which developed into complete quadriplegia was induced within 90 min after the beginning of the GI infusion in four out of seven patients. Only a slight paralysis of the legs was produced in another two patients and induction of an attack did not materialize in one. In four patients with complete quadriplegia, the mean values of serum sodium and potassium concentrations, haematocrit, plasma renin activity and plasma aldosterone slightly decreased immediately after the beginning of the GI infusion. Induction of a paralytic attack was not accompanied by any significant changes in serum sodium concentration, haematocrit, plasma renin activity and plasma aldosterone either 15 min before or after the onset of attack, while the serum potassium concentration progressively decreased, and an increase in plasma aldosterone associated with an increase of haematocrit and plasma renin activity reached a peak level at the stage of complete quadriplegia. On the other hand, in the three patients in whom an infusion produced slight or no paralysis of the legs, changes in the serum sodium concentration, haematocrit, plasma renin activity and plasma aldosterone were insignificant and the serum potassium concentration was slightly but insignificantly decreased.

These results suggest that hyperaldosteronism may not be a trigger for the induced paralytic attack but a phenomenon secondary to volume depletion and a change in potassium homoeostasis induced by GI infusion.
ADRENALINE IN THE HUMAN PANCREAS
Authors: Christensen N. J. , Neubauer B.
Published: December 2008

The present study describes the results of examinations of the noradrenaline and adrenaline concentrations in the human pancreas as well as in a number of other organs. Tissue specimens were obtained at postmortem examination.

Adrenaline was present in small amounts in the cardiovascular system, the liver and the spleen in comparison with the noradrenaline concentration. The pancreas, especially the body of the pancreas, contained, however, considerable amounts of adrenaline. The average adrenaline concentration was approximately 20 times higher in the pancreas than in the other organs examined. The greatest concentration of adrenaline was found in the posterior and superior parts of the body of the pancreas. There was no relationship between the cause of death in the human subjects and the adrenaline concentration in the pancreas and large amounts of adrenaline were also found in tissue specimens of pancreas obtained from long-term diabetic patients.

Adrenaline was present in the pancreas of the rat, dog and rabbit but in small amounts in comparison with the noradrenaline concentration.
GROWTH HORMONE RELATED TO INSULIN AND SUGAR IN NOCTURNAL BLOOD PLASMA OF LACTATING COWS
Authors: Halse K. , Blom Anne Kristine , Hove K.
Published: December 2008

Nocturnal blood plasma samples from about 190 indoor-fed cows at varying stages of the lactation cycle showed wide variations in the concentrations of sugar (43–88 mg/100 ml) and acetoacetate (0.12–8.7 mg/100 ml). Plasma immunoreactive insulin decreased and acetoacetate increased with decreasing sugar.

Plasma growth hormone (GH) was significantly correlated to insulin (r = −0.24, P < 0.001) and to sugar (r = −0.15, P < 0.05), but not to acetoacetate (r = +0.13).

Since the plasma level of GH in bovines is known to vary widely from hour to hour, individual cows are poorly represented by single determinations of the hormone. However, in accordance with the results from the correlation tests, different GH averages, about 11 and 9 ng/ml, were found for groups of animals with plasma sugar respectively below and above 70 mg/100 ml. By subgrouping according to insulin levels within sugar ranges, categories could be singled out with GH averages as different as 12.7 ng/ml (low sugar - low insulin) and 8.3 ng/ml (high sugar - high insulin).

The findings are consistent with the view that GH is involved in the regulation of energy metabolism in bovines. But no support has been provided for the hypothesis of GH hypersecretion as a cause of ketosis in cows.
STUDIES OF HUMAN CHORIONIC GONADOTROPHIN IN STEROID-PRIMED HYPOPHYSECTOMIZED RATS
Authors: Mizejewski Gerald J.
Published: December 2008

The uptake of [125I]HCG was studied in the ovaries of intact and hypophysectomized (Hypox) Sprague-Dawley rats. The [125I]HCG localized specifically in the ovary of the intact rat, and to a lesser extent, in the ovary of the hypox rat. The concentration of HCG in all other tissues and organs of either sex was negligible. However, the localization of [125I]HCG in the hypox rat was enhanced by the presence of exogenous steroids. The greatest increase in HCG uptake was observed in the rats primed with androgen; while a lesser enhancement was demonstrated in the oestrogen treated rats. Comparison of the ovary-to-body weight ratios revealed that a greater amount of HCG localized in the androgen-primed rats than in the oestrogen treated animals even though the ovaries of the former were smaller. These findings suggest that the hypox rat ovary primed with androgen could provide a highly sensitive animal model for further studies of the HCG cell receptor site in animals free of pituitary influence.
COMPARISON OF CIRCULATING GLYCOPROTEIN HORMONES AND THEIR SUBUNITS IN PATIENTS WITH OAT CELL CARCINOMA OF THE LUNG AND URAEMIC PATIENTS ON CHRONIC DIALYSIS
Authors: Hagen C. , Gilby E. D. , McNeilly A. S. , Ølgaard K. , Bondy P. K. , Rees Lesley H.
Published: December 2008

It has recently been suggested that the measurement of the glycoprotein hormones and their subunits in human serum may serve as biochemical markers of non-endocrine tumours. Using radioimmunoassays for LH, FSH, HCGβ-, LHβ- and the common α-subunit, significant differences in the levels of these substances could not be detected between patients with oat cell lung tumours and patients with chronic renal failure.

However, compared to normal subjects the α-subunit levels in serum were elevated in 12% of the male and 30% of the female patients with oat cell carcinoma of the lung and in 80 and 50% of the male and female patients, respectively, with chronic renal failure. The LHβ-subunit concentration was normal in all tumour patients and none of these patients had detectable (< 4 ng/ml) levels of HCGβ-subunit. While such measurements may be of value in relationship to particular neoplasms, it appears that raised levels of glycoproteins and their subunits may be found in other disease states.
CALCIUM AND STIMULUS SECRETION COUPLING IN THE NEUROHYPOPHYSIS
Authors: Robinson I. C. A. F. , Russell J. T. , Thorn N. A.
Published: December 2008

Slices from ox neurohypophyses were incubated in a calcium-free medium with the ionophores A23187 or X537A. X537A (5 × 10−5 mol/l) caused a marked release of vasopressin, neurophysin and protein to the medium. A23187 (2 × 10−5 mol/l) did not cause any release by itself, but when Ca2+ was added to the medium in the presence of the ionophore, an increase in the release of vasopressin, neurophysin and protein occurred. Release of lactate dehydrogenase and peptidase were not affected by the ionophores. The secretion caused by A23187 was abolished by D600 (a verapamil analogue) (2 × 10−5 mol/l) whereas the effect of X537A was unchanged.

The effects of X537A were strongly inhibited by removal of sodium from the medium. Re-addition of sodium to the medium caused a marked release. Gramicidin (10−6 or 5 × 10−5 mol/l) had no effect on secretion.

Efflux of 45Ca2+ from pre-loaded slices was drastically reduced in a sodium-free medium. X537A caused an increase in the efflux rate of 45Ca2+ both in medium with a normal concentration of sodium and when slices had been incubated in a sodium-free medium.

A23187 and X537A both released 45Ca2+ from a neurohypophyseal mitochondrial fraction. When sodium in a concentration of 20 mmol/l was added to this fraction, the Ca2+ accumulation was inhibited. This effect was reduced by inorganic phosphate up to a concentration of 2 mmol/l.
THE DEVELOPMENT OF A RADIOIMMUNOASSAY FOR ARGININE VASOPRESSIN
Authors: Freisenhausen Heinz-Dieter , Frahm Heinz , Čabrijan Tomislav , Wiethold Gerhard
Published: December 2008

The development of a sensitive and specific radioimmunoassay for vasopressin is described. Antibodies were successfully produced following the coupling of synthetic arginine vasopressin with bovine serum albumin carried out with carbodiimide. In order to standardize the assay, the labelled hormone has to be separated twice using a DEAE-Sephadex-A-25 column and thin layer chromatography with cellulose plates. A further condition to obtain a reproducible standard curve is the use of a pure arginine vasopressin checked by cellulose chromatography. Most of the vasopressin batches available do not fulfil this requirement of purity. With the method described, vasopressin can be determined in unextracted human urine. The lower limit of detection is 2 pg/ml. Normal values are in the range of 67.5 ± 34.3 ng/24 h (x̄ ± sd, n = 45). No significant difference of AVP excretion was found between men and women. The usefulness of the assay is demonstrated in patients with hypothalamic or pituitary disorders.
THE PANCREATIC ALPHA AND BETA CELLS RESPONSES TO 1-ARGININE AND INSULIN-INDUCED HYPOGLYCAEMIA IN HYPERTHYROIDISM
Authors: Shima K. , Sawazaki N. , Tanaka R. , Morishila S. , Tarui S. , Nishikawa M.
Published: December 2008

In order to assess the secretory capacity of the pancreatic alpha and beta cells in patients with hyperthyroidism, the plasma glucagon and insulin responses to 1-arginine and insulin-induced hypoglycaemia in 12 patients were compared with those in 6 normal subjects. The response of beta cell to hypoglycaemia was evaluated by measuring the decrease in plasma C-peptide immunoreactivity (CPR) level.

There was a negligible rise in blood glucose and plasma insulin levels in the patients, whereas a significant increase occurred in normal subjects during the arginine infusion. Although no difference in the fasting plasma glucagon concentration between the two groups was found, 30 min after the beginning of the arginine infusion, the plasma glucagon levels rose to a peak of 252 ± 35 pg/ml in the patients, a value significantly lower than 387 ± 53 pg/ml in the normal subjects. The insulin-induced hypoglycaemia caused no significant difference in the peak values of plasma glucagon between the two groups. There was a significant fall in plasma CPR after the insulin injection in both groups but the per cent decrement was rather greater in the patients than in the normal subjects.

These results suggest that the pancreatic alpha and beta cells in hyperthyroidism have a functional defect in response to 1-arginine but not to insulin-induced hypoglycaemia. The mechanism involved in these disorders is discussed.
DEMONSTRATION OF A PITUITARY GONADOTROPHIN HORMONE ACTIVITY IN THE MALE FOETAL MOUSE
Authors: Pointis G. , Mahoudeau J. A.
Published: December 2008

The testosterone production by 18-days-old foetal mouse testis was measured in an organ culture system, by RIA in the culture medium. This production was time-dependent, and could be stimulated by ovine LH and age-matched foetal pituitary. The gonadotrophin activity derived from foetal pituitary appeared to be released into the culture medium as a limited reserve. These data clearly show that a biologically active gonadotrophin material is present in the pituitary of the 18-days-old mouse foetus.
A CASE OF MALE PSEUDOHERMAPHRODITISM ASSOCIATED WITH ELEVATED LH, NORMAL FSH AND LOW TESTOSTERONE POSSIBLY DUE TO THE SECRETION OF AN ABNORMAL LH MOLECULE
Authors: Park I. James , Burnett Lonnie S. , Jones Howard W. , Migeon Claude J. , Blizzard Robert M.
Published: December 2008

A 27 year old female is described who had 46,XY chromosome complement, ambiguous external genitalia with elevated LH, slightly above normal FSH and low testosterone. Her plasma testosterone level increased 15–20 fold after HCG stimulation (5000 IU × 3). then returned to pre-stimulation level 3 months later. This was possibly due to the secretion of an abnormal LH molecule which is immunoreactive but biologically inactive in the human.
RADIOIMMUNOASSAY OF THYROTROPHIN RELEASING HORMONE IN HUMAN SERUM AND ITS CLINICAL APPLICATION
Authors: Mitsuma Terunori , Hirooka Yoshibumi , Nihei Noriyuki
Published: December 2008

A radioimmunoassay for thyrotrophin releasing hormone (TRH) in human serum is described.

Inactivation of TRH immunoreactivity by serum is prevented by a mixture of 8-hydroxyquinoline sulphate and Tween 20. This persisted for a long period and at the concentration used in this study did not affect the TRH value. The TRH was extracted from serum with methanol. The results of the recovery experiment, dilution curve of high TRH serum, intra-assay reproducibility and inter-assay variation were quite satisfactory. The lowest detectable amount in this system was 5.0 pg/ml.

Immunoreactive TRH levels in the serum were less than 60 pg/ml in normal subjects, were below the limit of detectability in hyperthyroid patients, were 40 to 400 pg/ml in primary hypothyroid patients, were 100 to 600 pg/ml in pituitary hypothyroid patients and below the limit of detectability in hypothalamic hypothyroid patients.

In primary hypothyroidism, immunoreactive TRH concentrations in the serum fell to in the normal range during thyroxine substitution. In most cases of hyperthyroidism, immunoreactive TRH concentrations in the serum increased to 5.0 pg/ml or more during antithyroid drug treatment, but in a few cases the level remained below the limit of detectability even though thyroid hormone levels were in the normal range.

The above data suggest that this assay system would be a useful tool to study the role of TRH in the hypothalamo-pituitary-thyroid axis.
EFFECT OF PROLACTIN SUPPRESSION ON GONADOTROPHIC SECRETION IN THE PUERPERIUM
Authors: Villalobos Hugo , Canales Elias S. , Zárate Arturo , Soria Jorge , MacGregor Carlos
Published: December 2008

Serum levels of prolactin (PRL), FSH, LH and oestradiol-17β were determined by radioimmunoassay in 57 lactating women and in 20 women in whom lactation was inhibited by ergocryptine (CB-154). Women who breast fed their infants exhibited high PRL levels which abruptly declined within 48 h post-partum, and remained low for the duration of the study. Serum FSH was undetectable during the first week post-partum in lactating as well as in CB-154 treated women. Thereafter, lactating women showed increasing FSH levels which reached a maximum by the third week post-partum. These FSH values were higher in lactating women than in the CBS-154 treated group. In contrast, LH levels were higher in those women receiving CB-154. Serum oestradiol-17β remained in low levels throughout the study, and no difference was observed between the two groups of subjects. From these results it seems that: 1) inhibition of PRL secretion leads to a faster recovery of gonadotrophin secretion toward the "menstrual type", and 2) PRL suppression produces no effect on the ovarian oestrogen production.
CONCENTRATION OF THYROID HORMONE IN SKELETAL MUSCLE
Authors: van Hardeveld C. , Kassenaar A. A. H.
Published: December 2008

1. A modified method for the determination of thyroid hormone levels in muscle is described.

2. The levels of T4 and T3 in skeletal muscle tissue of rats lie in the same range.

3. The level of T4 in plasma is about a hundred times higher than that of T3.

4. To remove plasma hormones from the tissue in which hormone levels are to be determined, the animals should be perfused with saline before tissue samples are taken.
ANTI-INSULIN-ANTIBODIES AND LATE DIABETIC COMPLICATIONS
Authors: Andersen O. Ortved
Published: December 2008

Two hundred and seventy-four insulin-dependent juvenile diabetics were examined. One hundred and sixty-six patients were without late diabetic complications, while 108 patients had one or more complications. At the time of the investigation patients with and without complications were found to have the same insulin requirement. Retrospectively it was observed, that after treatment for 10 years the insulin requirement was significantly higher among patients who had developed complications after treatment for 19 years as compared to patients who after 19 years of treatment had not developed complications.

One hundred and eighty-four patients, of which 110 were without and 74 with late diabetic complications were examined for anti-insulin-anti-bodies. Patients with complications, especially those with early onset of proliferative retinopathy or nephropathy had a slightly although insignificantly elevated plasma insulin-binding capacity. The frequency of high titres was significantly greater among patients with complications as compared to the frequency in patients without complications. The observations support the assumption, that insulin-anti-insulin-antibody complexes may aggravate the vascular complications.
EXISTENCE OF BIG AND LITTLE FORMS OF LUTEINIZING HORMONE IN HUMAN SERUM
Authors: Graesslin D. , Leidenberger F. A. , Lichtenberg V. , Glismann D. , Hess N. , Czygan P. J. , Bettendorf G.
Published: December 2008

Serum fractions from normal subjects obtained by gel chromatography have been investigated using three different assay systems: radioimmunoassay (RIA), radioligand receptor assay (RRA), and testosterone production assay (TPA). The bulk of immunoassayable and "bioassayable" LH-activity was found in two fractions differing widely in their molecular size. The slower moving component, designated as "little" LH, migrated identical to the radioiodinated pituitary hormone (LER 960) with a molecular weight of about 30 000, while "big" LH appeared in an elution volume consistent with a molecular weight range between 140 000 and 180 000. Concordance was seen between the LH-activities measured in all three assay systems. The RRA/RIA ratio varied between 1.6 and 8.9, the RRA/TPA ratio was close to unity. Treatment with 6 m urea and 0.1 % mercaptoethanol and also, exposure to different pH values and salt concentrations did not change the elution position of the two LH components. Also, "big" and "little" LH appeared unaltered after re-filtration and no conversion each other could be found. In another experiment injection of gonadotrophin releasing hormone (Gn-RH) into a male induced a profound shift of LH towards the low molecular weight species. Kinetic uptake studies with "big" and "little" LH using RRA showed identical affinities to the receptor preparation. Ion exchange chromatography of serum, however, did not give two LH components, indicating no major differences in charge properties. This finding could be confirmed by preparative gel isoelectric focusing. The RRA potencies following gel filtration were in good agreement with that applied to the column, however, the immunological activities exceeded that of loaded by a factor 3–4. A new aspect of serum LH heterogeneity is the finding of a low molecular substance (mol. weight approximately 1000) in the outer dialysate of serum, which has LH like activity in all three assay systems.
THE THYROTROPHIN RECEPTOR IN HUMAN THYROID PLASMA MEMBRANES: EFFECT OF SERUM IMMUNOGLOBULINS
Authors: Bryson Janet M. , Joasoo Aet , Turtle John R.
Published: December 2008

A homologous receptor assay system using human thyroid membranes and 125I-labelledhuman TSH (hTSH) was used to study the effect of serum and serum fractions on the binding of [125I]hTSH to the membrane. Scatchard analysis showed a single population of binding sites for TSH. Gamma globulin fractions prepared from sera of patients with Graves disease were able to displace [125I]hTSH from the membrane to a greater extent than normal gamma globulin in 21 out of 45 cases. Increased displacement activity was seen in patients with thyroiditis, hot nodules and euthyroid eye disease but not in patients with toxic multinodular goitres. Further fractionation of the gamma globulin fraction showed that the stimulatory activity was not confined to the IgG fraction. Scatchard plots showed gamma globulin fractions decreased the number of receptor sites available for TSH binding but did not alter the affinity of the receptor for TSH. IgG fractions showed different slopes and intercepts and appeared to decrease the affinity of the receptor for TSH. LATS activity in human serum may be explained on the basis of these observations on the properties of the TSH receptor.
AN INTER-LABORATORY COMPARISON OF TOTAL SERUM TRIIODOTHYRONINE DETERMINATION
Authors: Gordon Amirav , Gross Jack
Published: December 2008

L-triiodothyronine (T3) standards and an unknown serum were prepared and distributed to 18 different laboratories. T3 was determined on the standards and both T3 and T4 were assayed on the serum. The T3 and T4 results varied widely with a mean variance of 36 and 23%, respectively. There was, however, a positive correlation between the T3 values obtained within each laboratory and results of the unknown serum. Thus, while the data of each laboratory is internally consistent, the data between laboratories cannot be compared without an appropriate reference sera. From this fact, it is concluded that absolute ("true") T3 concentrations in human serum is not yet known.

Because of the small number of laboratories involved in this comparison, it was not possible to determine which factors of the various procedures are responsible for the variance of the T3 results.
THE INSULIN RECEPTOR IN NORMAL AND OBESE PERSONS
Authors: Beck-Nielsen Henning , Pedersen Oluf , Bagger Jens Peder , Sørensen Niels Schwartz
Published: December 2008

Using [125I]insulin at 172 pmol/l (1 ng/ml) the binding of insulin to mononuclear leucocytes isolated from peripheral blood was studied.

Our present study comprised 21 healthy subjects (22–33 years old, 90–110% of ideal weight) and a comparable group of 22 obese subjects (20–37 years old, minimum 150% of ideal weight). A significant difference in insulin binding was found between the two groups, the mean specific insulin binding fraction in normals being 1.92 ± 0.58 (s) × 10−2 and that for the obese 1.19 ± 0.41 (s) × 10−2 (P < 0.01).

No correlation was found between body weight and the number of insulin receptors in the obese subjects. However, the number of insulin receptors was negatively correlated to fat cell size (P < 0.05). Insulin receptors in subjects were also negatively correlated to fasting plasma insulin (P < 0.05).

Insulin receptors were studied in 11 obese subjects before and after 10 days of fasting. A significant increase in the number of insulin receptors was observed with a simultaneous decrease in plasma insulin to normal values.

The results indicate that obesity complicated by hyperinsulinism is associated with a decrease in the number of insulin receptors compared with the normal. This finding may in part explain the decreased insulin sensitivity of the hyperinsulinaemic obese.
CYANOKETONE-INDUCED INHIBITION OF ADRENAL 3β-HYDROXY-Δ5-STEROID OXIDOREDUCTASE ACTIVITY IN FEMALE AND MALE RATS IN VITRO
Authors: Gustafsson Sven A.
Published: December 2008

The inhibition of adrenal 3β-hydroxy-Δ5-steroid oxidoreductase activity was studied in vitro 24 h after a single injection of 2α-cyano-4,4,17α-trimethyl-5-androsten-17β-ol-3-one (cyanoketone) to adult castrated female and male rats. The inhibition of conversion of dehydroepiandrosterone1) to androstenedione was about 80 % as compared to adult castrated control rats treated with vehicle only. The conversion of pregnenolone to progesterone and 5α-pregnane-3,20-dione was also inhibited by about 80 % in both sexes. The activity of 3β-hydroxy-Δ5-steroid oxidoreductase was greater both in cyanoketone-treated and control female rats as compared to the corresponding male rats. It is concluded that the previously observed sex differences in response to cyanoketone in vivo are not due to a lower affinity of male adrenal 3β-hydroxy-Δ5-steroid oxidoreductase to cyanoketone.
MAMMOTROPHIC ACTIVITY IN RAT SERUM DURING THE OESTROUS CYCLE, PREGNANCY AND LACTATION
Authors: Peters J. M. , Uyldert I. E. , Ariëns A. Th.
Published: December 2008

The mammotrophic activity of various serum samples was assessed on the mammary gland of pregnant rats, in organ culture. Insulin was added to the medium. Serum samples from virgin rats showed little activity, and variation in mammotrophic activity during the oestrous cycle was slight. During pregnancy a significant increase in proliferative activity was not seen during the first week, but around day 8–9 mammotrophic activity increased sharply. The activity showed maxima around days 12 and 19. A decrease in the activity between these maxima was not consistently observed. Mammotrophic activity was still present in sera collected during parturition, and 30 min after parturition. It had disappeared completely within 24 h. The mammotrophic factor detectable by organ culture in the serum of pregnant rats could be rat chorionic mammotrophin.

Activity in the serum on day 0 and 1 of lactation was comparable to that of virgin rats, but some activity appeared on day 2. High activities were found frequently around day 4 to 6 of lactation. On other days the activity showed fluctuations without a definite pattern.

Litter size was of minor importance but the combination of a large litter size and fasting-overnight seemed to suppress the presence of mammotrophic activity in the serum. Nursing was important: after weaning the activity has disappeared, while renewed nursing after weaning resulted in the appearance of high levels of activity. The mitotic activity obtained with lactating rat serum in the culture was suppressed by addition of rabbit anti-rat prolactin serum to the medium. This suggests that the main mammotrophic factor detectable by organ culture in the serum of lactating rats, is prolactin.
INFLUENCE OF THE FOETUS, PLACENTA AND OVARY ON THE MAMMOTROPHIC ACTIVITY OF PREGNANT RAT SERUM
Authors: Peters J. M. , van Marie J.
Published: December 2008

Serum mammotrophic activity was assayed using an organ culture technique with histological endpoints. Using sera of 13 days pregnant rats with 1 to 18 conceptuses, activity was detectable even in the presence of 1 conceptus, but the activity with 1–4 conceptus(es) tended to be less than with 6–18. Serum of rats with 1–3 conceptus(es) was approximately 2–4 times less active than serum of rats with 14 conceptuses. Removal of the conceptuses on day 15 caused loss of mammotrophic activity of the serum, tested 4 days later. When the foetuses, the ovaries or both the foetuses and ovaries were removed on day 15 of pregnancy, mammotrophic activity was present in the serum collected 4 days later. Differences in activity between the treated groups were small. The mammotrophic activity was comparable to the activity of serum of untreated 15 days pregnant rats or 19 days sham-operated pregnant rats.

Explanted single fragments of a 19 days pregnant rat placenta released activity into the medium. The placenta retained this capacity even when the foetus had been removed 4 days previously.
EFFECTS OF TESTOSTERONE ON GONADOTROPHIN RESPONSES TO SYNTHETIC LH AND FSH RELEASING HORMONE (LRH) IN NORMAL MEN
Authors: Robyn C. , L'Hermite M. , Leclercq R. , Copinschi G.
Published: December 2008

LRH tests were performed in 6 adult men with intravenous injections of 25 μg, before and one week after an intramuscular injection of 250 mg testosterone oenanthate (Testoviron Depot®). One week after intramuscular injection of Testoviron the tonic secretion of LH was completely suppressed, but the reactivity or the reserve capacity of LH secretion, as tested by LRH, remained unchanged. In contrast, the tonic secretion of FSH and the reactivity of FSH secretion to LRH were both partly suppressed. Three months after the Testoviron injection, the basal levels of LH were still significantly lower than the control values, but the basal levels of FSH were identical to the control values. These data indicate that, in man, the feedback action of testosterone on gonadotrophin secretion could be exerted, at least for LH, at the hypothalamic level rather than at the pituitary level.

No significant effects of LRH were noted on the circulating levels of growth hormone and sugar. There was a distinct rise in serum prolactin, which was occasionally significant, within 30 min after LRH injection; this is considered to be without physiological significance.
DIURNAL VARIATIONS OF PLASMA AND PITUITARY THYROTROPHIN IN ADULT MALE AND FEMALE RATS
Authors: Jolín Trinidad , Pallardo Luis F. , Pericás Isabel
Published: December 2008

Male and female rats fed a low iodine diet for 20 days were used to study the diurnal variations in resting levels of plasma and pituitary TSH concentration using a highly sensitive radioimmunoassay. Sex differences in the fluctuations in plasma TSH levels and in amount of TSH in the pituitary gland were observed. The daily fluctuations of plasma TSH were characterized by two peaks that occurred in males at 6 a. m. and at 3 p. m., while in females the peaks were delayed until 9 a. m. and 7:30 p. m. Moreover, in the females the morning and the afternoon peaks were of the same intensity while in the males the afternoon peak that occurred just before the onset of darkness was much greater than the morning peak. There was a fall in TSH content of the pituitary in the male rats at 6 a. m. and also in the afternoon just before the onset of darkness. Thus, the diurnal variations in the plasma and pituitary TSH levels were related in male rats. In the females, however, the pituitary TSH concentration did not reflect the changes observed in the plasma TSH levels. The level of plasma PBI did not appear to be responsible for the fluctuations in plasma TSH concentration. It is suggested that the main mechanism for the control of the circadian rhythm of TSH might be related to a high activity at night.
ANTIGOITROGENIC EFFECT OF CASEIN
Authors: Gaitán Eduardo , Merino Héctor
Published: December 2008

Epidemiological findings from the city of Cali, Colombia, support the hypothesis that water supply and iodine intake are not the only dietary factors which influence the magnitude of the goitre endemia. Experiments were conducted in rats to determine whether casein has a counteracting effect on the goitrogenic and antithyroid activities of methimazole (MMI) and goitrogenic water extracts (GWE) from the endemic area of the Cauca Valley. Female albino rats (Charles River, DC strain) 100–110 g initial weight, receiving 12 μg of iodine daily, were divided into three groups and put on special diets: protein-free, 8% casein, or 60% casein, respectively. Each group (24 rats) was then divided into three subgroups. Subgroup one received goitrogen-free water and was used as a control. Subgroup two was administered MMI, 50 μg/day/rat. Subgroup three was given per animal a daily amount of GWE equivalent in antithyroid potency to 50 μg of MMI. At 77 days, the thyroid glands were studied for weight, 131I uptake, and 127I concentration. Animals on the protein-free diet showed significantly (P < 0.05 – < 0.01) larger thyroid glands per 100 g body weight and lower thyroidal 4 h 131I uptake and 127I-concentrations than rats on casein diets. These differences were significantly increased (P < 0.01) by the administration of MMI and GWE. All the effects were completely reversed by the 60 % casein diet showing no differences between control rats and those on MMI or GWE. Rats on 8 % casein showed intermediate values between those of animals on protein-free and 60% casein diets; differences were still present between the control as against the MMI or GWE groups. The results indicate that under these experimental conditions, a poor-protein diet impairs the thyroidal transport of iodine, decreases its concentration in the thyroid and is accompanied by an enlargement of the gland. Under these circumstances, the action of thiourea-like antithyroid agents is enhanced. The administration of protein reverses these alterations and decreases the action of such antithyroid agents. Whether the changes observed are due to a direct action of casein on the thyroid and/or to effects of malnutrition on the metabolism of antithyroid compounds remains to be determined.
IMMUNOREACTIVE ACTH, IMMUNOREACTIVE HUMAN CHORIONIC SOMATOMAMMOTROPHIN (HCS) AND 11-OH STEROIDS PLASMA LEVELS IN NORMAL AND PATHOLOGICAL PREGNANCIES
Authors: Genazzani A. R. , Felber J. P. , Fioretti P.
Published: December 2008

Plasma immunoreactive ACTH (I. R. ACTH), immunoreactive human chorionic somatomammotrophin (I. R. HCS) and 11-OH steroids levels were measured during normal and pathological pregnancies. Plasma I. R. ACTH levels were found to be above normal during pregnancy, with a slight decrease near term. This observation correlates well with the recent description of human chorionic corticotrophin (HCC), i. e. a factor of placental origin possessing a high biological adrenocorticotrophic activity and presenting partial immunological cross-reaction with human ACTH. The 11-OH steroids levels, as measured by a fluorimetric method, increased regularly during pregnancy but, unlike ACTH, reached their highest value near term, I. R. HCS increased progressively until term when a slight decrease was observed.

In pathological pregnancies, I. R. ACTH levels behaved like other placental hormones. On the contrary, 11-OH steroids levels remained generally unmodified. Treatment with high doses of prednisolone caused no inhibition of the plasma I. R. ACTH and of plasma 11-OH steroids levels. These data suggest placental autonomy of the secretion of HCC and low adrenal responsiveness to endogenous ACTH variations throughout pregnancy.
EFFECT OF AN ANABOLIC STEROID (METANDIENON) ON PLASMA LH, FSH, AND TESTOSTERONE AND ON THE RESPONSE TO INTRAVENOUS ADMINISTRATION OF LRH
Authors: Holma Pentti , Adlercreutz Herman
Published: December 2008

Plasma levels of testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) as well as the response of LH and FSH to the intravenous administration of 100 μg of luteinizing hormone releasing hormone (LRH) were measured in 16 well-trained athletes (mean age 30 years) before and after 2 months of daily oral intake of 15 mg of metandienon, an anabolic steroid (Anabolin®, 17α-methyl-17β-hydroxy-1,4-androstadien-3-one, Medica, Finland). All athletes continued to train regularly, just as they had done for several years.

During administration of metandienon the mean plasma testosterone level fell 69%, from 29.4 ± 11.6 nmol/l to 9.1 ± 7.5 nmol/l. The mean plasma levels of LH and FSH also fell significantly (P < 0.001 and P < 0.01, respectively), both about 50%. Because LH and FSH levels were low after administration of the steroid the maximum stimulation values after LRH administration were also lower than pre-treatment values although the mean increments did not differ significantly before and after administration of the anabolic steroid. However, after treatment, the FSH response curve had a biphasic pattern in most subjects, with peaks at 10 to 20 and 50 to 60 min after the iv injection of LRH. Administration of LRH after the treatment period had no effect on FSH secretion in two subjects and no effect on LH secretion in one. Our results show that administration of an anabolic steroid causes a pronounced lowering of plasma levels of testosterone, LH and FSH but causes no gross alteration in the response of LH secretion to stimulation by LRH. The reason for the biphasic response pattern of FSH to LRH administration in most subjects is not known.
ANTIGONADOTROPHIC EFFECT OF PROLACTIN IN ADULT CASTRATED AND IN IMMATURE FEMALE RATS
Authors: Beck W. , Engelbart S. , Gelato M. , Wuttke W.
Published: December 2008

High serum prolactin levels were induced in chronically castrated female rats by pituitary transplants from male donor rats. The typical pulsatile LH release pattern observed in castrated control rats was maintained in pituitary grafted rats, when pituitary transplantation was performed simultaneously with castration 3 months before withdrawal of the blood samples. If pituitaries were transplanted into chronically castrated rats and blood samples were withdrawn 3 days later, the pulsatile LH release was abolished and basal or moderately elevated LH levels were found. Chronically or subacutely elevated prolactin levels had no effect on high serum FSH values.

Pituitary transplants into intact female rats at day 23 after birth also suppressed basal LH values for 4 days without alterating the serum FSH levels. Six and 8 days after transplantation the serum LH levels were normal. Pituitary transplantation into these immature rats advanced puberty by more than one week.

These results indicate that prolactin has an antigonadotrophic effect in female rats which is directed only towards pituitary LH but not FSH secretion. The inhibitory action of high serum prolactin levels on pituitary LH release does not last longer than 4–6 days under steady state conditions, such as found in the constantly high prolactin levels due to pituitary transplants. Under natural conditions with steadily increasing prolactin levels between day 20 and puberty the effect of prolactin in inhibiting pituitary LH release may last longer. Thus, prolactin may be one of the, if not the regulator of the timing of puberty.
ADRENAL ACTIVITY DURING NORMAL GLUCOSE TOLERANCE
Authors: Sober Arthur J. , Ruder Henry J. , Sode Jonas
Published: December 2008

Plasma cortisol was measured by radioimmunoassay during 4 h oral glucose tolerance tests in 8 non-obese normal subjects. Following 100 g of glucose, plasma cortisol concentrations were lower than basal at 15, 30 and 60 min, and declined with a half-time of 70 min. No evidence was obtained that the hyperglycaemia which follows glucose ingestion leads to increased cortisol secretion and that such a mechanism is involved in the stabilization of blood sugar levels during the posthyperglycaemic phase of the normal oral glucose tolerance test. Epinephrine and norepinephrine excretory rates during the hyperglycaemic (0–2 h) and euglycaemic (2–4 h) phases of the test were not significantly different. It is concluded that adrenocortical and adrenomedullary activities are not increased during normal glucose tolerance in man.