Procollagen type 1 amino-terminal propeptide (P1NP) and risk of hip fractures in elderly Norwegian men and women. A NOREPOS study

The current study aimed to assess a possible association between the bone turnover marker procollagen type 1 amino-terminal propeptide (P1NP) and future hip fractures in elderly Norwegian men and women and to elucidate the relation between P1NP, bone mineral density and 25-hydroxyvitamin D (25(OH)D). Men and women aged 71 to 77 from two population based health studies in Norway (1999-2001) were followed for a median period of 7.3 years with respect to hip fractures. The study was designed as a case-cohort study. P1NP and 25(OH)D were analysed in frozen serum samples obtained at baseline in hip fracture patients (n=340) and in randomly selected sex stratified sub-cohorts. Bone mineral density was measured by dual-energy X-ray absorptiometry (DXA) in a subset of participants. Cox proportional hazards regression with inverse probability weighting and robust variance was performed. No significant correlation between 25(OH)D and P1NP was found. A negative correlation between P1NP and BMD was observed in women (Rho=-0.36, p=0.001). A similar trend was observed in men. No association between quartiles of P1NP and rate of subsequent hip fractures was found. Spline analyses suggested a higher rate of hip fracture at P1NP levels above 60 μg/L in both men and women. A higher hip fracture rate, which was independent of BMD, was also indicated in women with very low levels of P1NP.

Revealing genetic relationships between compounds affecting boar taint and reproduction in pigs

Boar taint is characterized by an unpleasant taste or odor in intact male pigs and is primarily attributed to increased concentrations of androstenone and skatole and to a lesser extent by increased indole. The boar taint compounds skatole and indole are produced by gut bacteria, metabolized in the liver, and stored in the fat tissue. Androstenone, on the other hand, is synthesized in the testis along with testosterone and estrogens, which are known to be important factors affecting fertility. The main goal of this study was to investigate the relationship between genetic factors involved in the primary boar taint compounds in an attempt to discover ways to reduce boar taint without decreasing fertility-related compounds. Heritabilities and genetic correlations between traits were estimated for compounds related to boar taint (androstenone, skatole, indole) and reproduction (testosterone, 17β-estradiol, and estrone sulfate). Heritabilities in the range of 0.47 to 0.67 were detected for androstenone concentrations in both fat and plasma, whereas those for skatole and indole were slightly less (0.27 to 0.41). The genetic correlations between androstenone in plasma and fat were extremely high (0.91 to 0.98) in Duroc and Landrace. In addition, genetic correlations between androstenone (both plasma and fat) and the other sex steroids (estrone sulfate, 17β-estradiol, and testosterone) were very high, in the range of 0.80 to 0.95. Furthermore, a genome-wide association study (GWA) and a combined linkage disequilibrium and linkage analysis (LDLA) were conducted on 1,533 purebred Landrace and 1,027 purebred Duroc to find genome regions involved in genetic control of the boar taint compounds androstenone, skatole, and indole, and sex hormones related to fertility traits. Up to 3,297 informative SNP markers were included for both breeds, including SNP from several boar taint candidate genes. From the GWA study, we found that altogether 27 regions were significant at a genome-wide level (P < 0.05) and an additional 7 regions were significant at a chromosomal level. From the LDLA study, 7 regions were significant on a genome-wide level and an additional 7 regions were significant at a chromosomal level. The most convincing associations were obtained in 6 regions affecting skatole and indole in fat on chromosomes 1, 2, 3, 7, 13, and 14, 1 region on chromosome 6 affecting androstenone in plasma only, and 5 regions on chromosomes 3, 4, 13, and 15 affecting androstenone, testosterone, and estrogens.

No improvement in cardiovascular risk factors in overweight and obese subjects after supplementation with vitamin D3 for 1 year

BACKGROUND AND AIM

Cross-sectional studies indicate vitamin D to be of importance for glucose tolerance, blood pressure and serum lipids, but whether supplementation with vitamin D would improve cardio-vascular risk factors is not known.

DESIGN AND SETTING

The study was a 1 year, double blind placebo-controlled intervention trial performed at the University Hospital of North Norway from November 2005 to October 2007. Subjects. A total of 438 overweight or obese subjects, 21-70 years old, were included and 330 completed the study.

INTERVENTIONS

The subjects were randomized to vitamin D (cholecalciferol, vitamin D(3)) 40 000 IU per week (DD group), vitamin D 20 000 IU per week (DP group), or placebo (PP group). All subjects were given 500 mg calcium daily.

MAIN OUTCOME MEASURES

Fasting serum lipids and blood pressure were measured and an oral glucose tolerance test performed at start and end of the study.

RESULTS

At baseline the mean serum 25(OH)D levels were 58 nmol L(-1) (all subjects) and increased to 140 and 101 nmol L(-1) in the DD and DP groups, respectively. No significant differences were found between the three groups regarding change in measures of glucose metabolism or serum lipids. In the DP group, there was a slight but significant increase in systolic blood pressure compared with the placebo group.

CONCLUSIONS

Our results do not support a positive effect of vitamin D on glucose tolerance, blood pressure or serum lipids. Further studies in subjects with low serum 25(OH)D levels combined with impaired glucose tolerance, hypertension or dyslipidaemia are needed.

Sugar profiling proves that human serum erythropoietin differs from recombinant human erythropoietin

Erythropoietin (EPO) from sera obtained from anemic patients was successfully isolated using magnetic beads coated with a human EPO (hEPO)-specific antibody. Human serum EPO emerged as a broad band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight slightly smaller than that of recombinant hEPO (rhEPO). The bandwidth corresponded with microheterogeneity because of extensive glycosylation. Two-dimensional gel electrophoresis revealing several different glycoforms confirmed the heterogeneity of circulating hEPO. The immobilized anti-hEPO antibody was capable of binding a representative selection of rhEPO glycoforms. This was shown by comparing normal-phase high-performance liquid chromatography profiles of oligosaccharides released from rhEPO with oligosaccharides released from rhEPO after isolation with hEPO-specific magnetic beads. Charge analysis demonstrated that human serum EPO contained only mono-, di-, and tri-acidic oligosaccharides and lacked the tetra-acidic structures present in the glycans from rhEPO. Determination of charge state after treatment of human serum EPO with Arthrobacter ureafaciens sialidase showed that the acidity of the oligosaccharide structures was caused by sialic acids. The sugar profiles of human serum EPO, describing both neutral and charged sugar, appeared significantly different from the profiles of rhEPO. The detection of glycan structural discrepancies between human serum EPO and rhEPO by sugar profiling may be significant for diagnosing pathologic conditions, maintaining pharmaceutical quality control, and establishing a direct method to detect the misuse of rhEPO in sports.

Reproductive function in male rats after brief in utero exposure to diethylstilboestrol

Long-term effects of brief in utero exposure to diethylstilboestrol (DES) during a foetal period known to be critical for gonadal development were evaluated. Rats were exposed to DES (100 microg/kg body-weight) from day 17 to 19 of pregnancy. All of the DES-treated pregnant rats (11/11) ate parts or whole of their offspring during the first day after birth (p=0.03). Surviving male offspring were examined on day 63 post-partum. DES induced a reduction in weight of the testis (p=0.06) and ventral prostate (p=0.07), even after this short exposure. DES tended to reduce the number of Sertoli cells (p=0.13). Our findings indicate that even a short in utero exposure of rats to DES during a critical period for gonadal development results in cannibalism and reduced testis and ventral prostate weight.

Leptin and leptin binding activity in the preovulatory follicle of polycystic ovary syndrome patients

To investigate the clinical importance of leptin's intraovarian effects, we studied the concentration of leptin and leptin binding activity in the plasma and in the follicular fluid of PCOS patients (n=20; median BMI: 27.1 kg/m2, range 19.7-36.3) undergoing controlled ovarian stimulation with long-term GnRH agonist, recombinant FSH, and in vitro fertilization. Follicular fluid and blood samples were collected during follicle aspiration for IVF. Total leptin concentration was measured by radioimmunoassay, and specific leptin binding activity was accessed by a gel filtration column assay. Follicular fluid and plasma leptin levels were similar (median 1135 pmol/l vs. 1409 pmol/l; p=0.81). Follicular fluid to plasma leptin ratio was independently associated with cumulative FSH dose (r=0.63; p=0.006) and insulin resistance index (r=-0.45; p=0.04). Specific leptin binding activity was higher in the plasma than in the follicular fluid [median 7.94% vs. 3.49%; p<0.001]. When multivariate analysis was used to predict FSH consumption, only follicular fluid leptin levels were significantly associated with cumulative FSH dose (r=0.46; p=0.04). We infer that at least in part by increased intrafollicular leptin levels, obesity directly affects ovarian function in PCOS, and may induce a relative resistance to gonadotropin stimulation. This intraovarian effect of leptin can be even more profound because of low leptin binding activity in the preovulatory follicle of obese patients.

Monday and non-Monday concentrations of lifestyle-related blood components in the Oslo Diet and Exercise Study

OBJECTIVE

We hypothesized that participants of intervention studies have an unfavourable lifestyle at the weekend compared with the rest of the week, thus affecting the concentrations of components in samples drawn on Mondays.

DESIGN

The hypothesis was examined using data from the Oslo Diet and Exercise Study, a 2 x 2 randomized intervention trial on diet and exercise involving 209 participants. Each person chose which day of the week to attend for blood sampling, both before and after the 1 year of intervention.

MAIN OUTCOME MEASURES

Comparison of mean concentrations of the components measured, in samples drawn on Mondays vs. non-Mondays, both at the start and at the end of intervention.

RESULTS

At the start, nine components, from haemostasis, carbohydrate and lipid metabolism, showed a difference of more than 10% between Monday and non-Monday values, all Monday values differing from the non-Monday values in a cardiovascularly unfavourable direction. Participants starting and ending on a Monday showed the unfavourable profile both times, and those who were examined both times on a non-Monday showed a consistently favourable profile, whereas those who changed the day of examination at the start and end changed profile accordingly.

CONCLUSION

The lifestyle-related components examined here showed differences between Monday and non-Monday values, which were not due to a selection bias. We suggest they may be related to a different lifestyle at the weekend compared with ordinary working days. If such effects are not recognized and properly taken into account, they may markedly affect the outcome of intervention studies.

Interferon-gamma affects protein kinase C activity in human neutrophils

Interferon-gamma (IFN-gamma) is a priming agent of polymorphonuclear neutrophilic granulocyte (PMN) oxygen metabolism, and protein kinase C (PKC) is traditionally believed to play a central role in activation of this oxygen metabolism. In the present study, we have shown that the PKC activity in PMN is affected by IFN-gamma. After only 2 minutes exposure to IFN-gamma (100 U/ml), PKC activity was significantly increased in the noncytosolic fraction of the cells. This increase was transient, but toward the end of the priming period of 2 h, the membrane-associated PKC activity increased again to about 152% of control. In the cytosolic fraction, a small and hardly detectable decrease in PKC activity was observed. Treatment of PMN with granulocyte-macrophage colony-stimulating factor (GM-CSF), another PMN priming agent, showed no significant effects on the PKC activity. When the cells were stimulated with the bacterial peptide fMLP after a priming period with IFN-gamma or GM-CSF for 2 h, no significant difference between treated and control cells could be observed. PMN oxygen metabolism, measured by flow cytometry as an accumulation of the fluorescent compound dichlorofluorescein, was in these experiments significantly primed by IFN-gamma, both at baseline and when stimulated with fMLP. The protein kinase C inhibitors H7 and Ro31-8220 blocked the fMLP responses to some extent, but not completely. However, no significant difference between fMLP responses in control and IFN-gamma-treated cells could be detected after administration of inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency of hyperprolactinaemia due to large molecular weight prolactin (150-170 kD PRL)

Of 605 hyperprolactinaemic sera (prolactin > 1000 mU l-1 determined with PRL DELFIA, Wallac) in the routine diagnostic (PRL was measured in 10,737 sera) 26% had an increased amount of PRL with molecular weight (MW) = 150-170 kD (150-170 kD PRL or bigbig PRL). In a series of serum samples from 660 healthy subjects, only one female with hyperprolactinaemia due to increased 150-170 kD PRL was found. The 150-170 kD PRL constituted less than 1% of the total PRL found in 11 patients with prolactinoma (macroprolactinoma, PRL 8800-500,000 mU l-1). When determined with five different commercially available immunometric assays, the PRL values in the sera with large amounts of 150-170 kD were increased in all sera in four of five assays, although they varied widely. The clinical implications of hyperprolactinaemia due to increased 150-170 kD PRL are still uncertain.

Insulin and PAI-1 levels during oral glucose tolerance test in patients with coronary heart disease

The present study was performed to investigate the acute effects of physiologically induced hyperinsulinemia on plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA) and triglycerides (TG). Forty-one male patients with chronic coronary heart disease (CHD) and moderate hypertriglyceridemia were studied for 3 h; 33 of them during an oral glucose tolerance test (OGTT), whereas eight patients served as controls, receiving water only. All subjects in the OGTT group were adequate responders to glucose administration, giving peak values of glucose (median 6.90 mmol l-1) and insulin (median 123 mU l-1) after 1 h. TG were unchanged throughout the test period in both groups. After 1 h PAI-1 activity and antigen decreased significantly more in the OGTT group than in the controls (median values: PAI-1 act 23-12 vs. 12-12 U ml-1; (p < 0.001). PAI-ag 45-35 vs. 18-16 ng ml-1 (p < 0.05)). t-PA increased more in the OGTT group (0.70-1.20 vs. 0.50-0.63 IU ml-1 (p = 0.08)). These differences tailored off after 3 h. We conclude that acute hyperinsulinemia, when generated during an OGTT, stimulates fibrinolysis with a consequent decrease in PAI-1 activity, but give no change in TG. The postulated regulating role of insulin for the steady state levels of PAI-1 could probably not be elucidated in the present dynamic model.

Inhibition of polyphosphoinositide breakdown and c-myc induction accompanying inhibition of human B-cell activation by two monoclonal antibodies against the leucocyte common antigen (CD45)

In this report we show that the two monoclonal anti-CD45 antibodies, EO-1 and FN-126, potently inhibit G0 to G1 transition and S phase entry in human B cells stimulated with anti-mu and low molecular weight B-cell growth factor. Both antibodies were found to inhibit anti-mu-induced inositol phospholipid breakdown and c-myc mRNA induction. In contrast, EO-1 and FN-126 only partially inhibited the early anti-mu-induced increase in cytoplasmic Ca2+ levels, both in normal and in Ca2(+)-depleted medium. B-cell activation provoked by 12-O-tetradecanoylphorbol 13-acetate (TPA) was not inhibited by these antibodies, except when using high concentrations of EO-1. In addition, both antibodies were found to inhibit G1 entry induced by the anti-CD20 antibody 1F5, which confers an activation of B cells without any detectable increase in [Ca2+]i or in phospholipid metabolism. This indicates that alternative mechanisms in addition to the inhibition of polyphosphoinositide (PI) breakdown are involved in the inhibitory action of these antibodies.

The mechanisms by which vasoactive intestinal peptide (VIP) and thyrotropin releasing hormone (TRH) stimulate prolactin release from pituitary cells

The effect of vasoactive intestinal peptide (VIP) on prolactin (PRL) secretion from pituitary cells is reviewed and compared to the effect of thyrotropin releasing hormone (TRH). These two peptides induced different secretion profiles from parafused lactotrophs in culture. TRH was found to increase PRL secretion within 4 s and induced a biphasic secretion pattern, while VIP induced a monophasic secretion pattern after a lag time of 45-60 s. The secretion profiles are compared to changes in adenylate cyclase activity, production of inositol polyphosphates, changes in intracellular calcium concentrations and changes in electrophysiological properties of the cell membrane.

Early morning glycaemia and the metabolic consequences of delaying breakfast/morning insulin. A comparison of continuous subcutaneous insulin infusion and multiple injection therapy with human isophane or human ultralente insulin at bedtime in insulin-dependent diabetics

We studied morning glycaemia and metabolic consequences of delaying morning insulin/breakfast in insulin-dependent diabetics on (i) continuous subcutaneous insulin infusion (CSII) (n = 27), (ii) multiple-injection therapy (MI) with human isophane insulin at bedtime (MI/human isophane) (n = 23) and (iii) MI with human ultralente insulin at bedtime (MI/human ultralente) (n = 14). After an overnight fast, food and insulin (except for the basal infusion on CSII) were withheld, and blood glucose, serum free insulin and serum betahydroxybutyrate were followed from 0800 hours to 1300 hours. At all times blood glucose was lowest on CSII, intermediate on MI/human isophane and highest on MI/human ultralente; serum free insulin was highest on CSII, intermediate on MI/human ultralente and lowest on MI/human isophane; serum betahydroxybutyrate was lowest on CSII, intermediate on MI/human ultralente and highest on MI/human isophane. Blood glucose rose significantly on MI/human isophane (p less than 0.001) and CSII (p less than 0.02); serum free insulin declined significantly on MI/human isophane (p less than 0.001), and betahydroxybutyrate rose significantly on all regimens. Morning metabolic control is better with CSII than MI. Human isophane insulin is preferable to human ultralente insulin overnight in MI. Delaying morning insulin is not advisable on intensified insulin regimens, being most unfavourable with MI/human isophane.

Intracellular events associated with inhibition of B cell activation by monoclonal antibodies to HLA class II antigens

We have investigated several aspects of the inhibitory effects of monoclonal antibodies (mAb) directed against MHC class II antigens in B cell activation/proliferation, using a panel of mAb specifically reactive with antigens encoded by HLA class II loci (DP, DQ, DR). All mAb except the anti-DP mAb inhibited significantly anti-mu plus B cell growth factor-induced DNA synthesis. Only one mAb, however, which was reactive with gene products of all three class II loci (DP, DQ, DR) inhibited anti-mu-induced DNA synthesis as well as c-myc mRNA expression. In addition, the same mAb inhibited the early events induced by anti-mu stimulation alone, including phosphatidylinositol turnover and elevation of [Ca2+]i. In contrast to previous findings in the murine system, none of the anti-MHC class II mAb used in this study increased the cAMP levels.

A transplantable rat Leydig cell tumour. 6. Effect of castration and hypophysectomy on tumour growth, morphology and plasma levels of pituitary hormones and testosterone

Growth rate and morphology were studied in a transplantable rat Leydig cell tumour (H-540) grown in intact, castrated and hypophysectomized rats. The plasma levels of pituitary hormones and testosterone were measured in the same rats. The results can be summarized as follows: 1. The growth curves of tumours in intact and castrated rats were S-shaped and very similar during the observation period of three weeks. 2. In hypophysectomized rats, the onset and progression of tumour growth were delayed, compared with intact and castrated rats. 3. The thymidine labelling index as well as the size of the S and G2 phase compartments were decreased in tumours greater than 10 g compared with smaller tumours and tumours grown in hypophysectomized rats. 4. Testosterone concentrations in plasma correlate well with increasing tumour weight up to approximately 10-15 g in intact and castrated rats. 5. Plasma testosterone levels in tumour-bearing hypophysectomized rats were 7-fold higher than those of corresponding intact and castrated rats. 6. In castrated rats, suppression of LH production occurs by very small tumours (less than 2 g), whereas FSH levels show a gradual decrease with increasing tumour size. PRL production was independent of castration, tumour weight, and testosterone levels. 7. In spite of no major differences in cell morphology, the morphometric analysis revealed a reduction in tumour cell size and nuclear size in hypophysectomized rats compared with intact and castrated rats. It is concluded that pituitary hormones stimulate tumour growth, but surprisingly appear to reduce the secretion of testosterone from these tumours.

Cyclic AMP has the ability to influence multiple events during B cell stimulation

Negative regulators of cellular proliferation are important in maintaining a balanced growth control. In this study we have examined the effects of the diterpene forskolin on various parameters of B cell activation. Forskolin is known to elevate intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels and thereby to influence B cell stimulation. We found that forskolin exerted an inhibitory effect on early as well as late events during stimulation of resting normal human B cells. Cells were activated either by antibodies to surface immunoglobulins (anti-mu), by the monoclonal antibody 1F5 reactive with the CD20 antigen or by 12-O-tetradecanoylphorbol 13-acetate. While anti-mu stimulation induces increased phosphatidylinositol (PI) turnover and [Ca2+]i fluxes, the latter two reagents confer an activation of B cells independent of the PI/Ca2+ pathway. We found a clear inhibitory effect of forskolin on the anti-mu-induced PI turnover and [Ca2+]i fluxes as well as on later parameters of cell activation. There was also a clear inhibition of G1 entry and DNA synthesis when PI/Ca2+-independent activation was employed, indicating that cAMP interferes with B lymphocyte stimulation in several ways. Importantly, forskolin maintained its inhibitory effect when added late after anti-mu stimulation, implying an effect also at multiple stages of activation. When examining the inhibitory effect of forskolin on neoplastic B cells, we found essentially no differences from the responses in normal cells.

Phorbol esters and thyroliberin have distinct actions regarding stimulation of prolactin secretion and activation of adenylate cyclase in rat pituitary tumour cells (GH4C1 cells)

The phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) enhances the effects of TRH on phase II of prolactin secretion as well as on hormone synthesis at both low and high TPA receptor occupancy. Furthermore TPA, but not the biologically inactive substance 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), stimulates the particulate bound adenylate cyclase with a time course paralleling that of TRH activation. However, the combined additions of TRH and TPA activate this cyclase in an additive manner while the Gpp(NH)p- and the forskolin-sensitive enzyme are unaffected by TPA addition. Polymyxin B, which inhibits protein kinase C, abolishes activation of adenylate cyclase by TPA without interfering with the stimulatory action of TRH. Also, when phosphatase activity is preferentially inhibited by pretreatment of the cells with sodium vanadate, the TRH-sensitive cyclase is unaltered, while TPA activation is obliterated. Maximal stimulation of adenylate cyclase by cholera toxin pretreatment, obliterated the actions of TRH and TPA. Cells pretreated with pertussis toxin retained their TRH-sensitive cyclase, however, TPA-responsiveness was lost. We therefore suggest that the action of TPA as it relates to activation of adenylate cyclase, is probably mediated via the Gi component of the adenylate cyclase complex, while TRH stimulates the enzyme via the classical pathway involving the stimulatory GTP binding protein (Gs).

Increase in insulin antibodies during continuous subcutaneous insulin infusion and multiple-injection therapy in contrast to conventional treatment

Forty-five insulin-dependent diabetics were randomized to 1 yr treatment with either continuous subcutaneous insulin infusion (CSII), multiple insulin injections (MI), or continued conventional treatment. The CSII group used regular insulin only, the MI group used 4-6 premeal injections of regular insulin and intermediate insulin at night, and the conventional group used two daily injections of combined regular and intermediate insulin. Only highly purified porcine insulin was used. Near normoglycemia was obtained during CSII and MI but not during conventional treatment. Antibodies against insulin were measured in serum samples by measuring the binding of iodinated porcine insulin to serum after removal of free and antibody-bound insulin from the samples by acid charcoal. The percent binding of 125I-labeled insulin increased significantly during MI and CSII, in contrast to conventional treatment. Nineteen patients had sufficient binding capacity for Scatchard analysis. In the CSII and MI groups, high- or low-affinity antibodies or both were induced. When insulin was administered subcutaneously during MI or CSII for 1 yr, the insulin antibody production increased, in contrast with conventional treatment.

Determination of the R-protein and the R-protein-vitamin B12-complex in saliva and gastrointestinal juice by FPLC Mono S cationic chromatography

The binding of vitamin B12 to the two vitamin B12 binding proteins--intrinsic factor and R-protein--in gastrointestinal juice is pH dependent. It is therefore of importance that binding studies are carried out at pH values near the physiological pH of the gastric juice. In the present study the vitamin B12 complexes of the two vitamin B12 binders were separated at a pH of 1.8 using the cationic exchange chromatograph Mono S attached to the fast protein liquid chromatography (FPLC) system. The R-protein concentration was measured in saliva and gastric juice with high accuracy and with highly significant correlation compared to the serum-coated charcoal method of Gottlieb. The method showed a decreased recovery in duodenal juice and in samples with high bile content.

Properties and regulation of GnRH receptors in the anterior pituitary and the testis of the rat: different response of Leydig cell LH and GnRH receptors to hormonal treatments

The properties (association and dissociation rates, affinity and specificity) of GnRH receptors in the rat pituitary and the Leydig cells are very similar. In addition, in vivo administration for 5 or 11 days of 10 micrograms of GnRH to adult rats resulted in an increase (p less than 0.01) in both Leydig cell and pituitary GnRH receptors. In contrast, the same treatment caused a significant decrease (p less than 0.01) of Leydig cell LH receptor number. Furthermore, testosterone propionate (500 micrograms/day), which had no effect on Leydig cell LH receptors, caused a significant increase (p less than 0.01) of testicular GnRH receptors but a decrease (p less than 0.01) of pituitary GnRH receptors. Estradiol 17 beta valerate (5 micrograms/day) reduced (p less than 0.01) both testicular (5 days) and pituitary (5 and 11 days) GnRH receptors. Such treatment for 5 days also decreased (p less than 0.05) the Leydig cell LH receptors. No effect of dexamethasone and 17-hydroxyprogesterone was seen after 5 or 11 days of treatment. Thus, although pituitary and Leydig cell receptors appear similar, their regulation by exogenous hormone treatments is different. Furthermore, the regulation of Leydig cell GnRH and LH receptors also appears very different, suggesting different roles of the receptors in the control of the Leydig cell function.

A transplantable rat Leydig cell tumor--1. LH and prolactin receptors and effects of the endocrine status of the host animal

We have examined the binding capacity and properties (affinity, specificity) of LH and prolactin (Prl) receptors in a transplantable rat Leydig cell tumor (H-540) grown in intact, castrated and hypophysectomized rats. LH receptors in adult rat testis and Prl receptors in the rat ventral prostate were examined simultaneously for comparison. The results can be summarized as follows: The qualitative properties (affinity, specificity) of LH and Prl receptors in tumor Leydig cells appear to be identical to those of corresponding receptors in non-tumor tissues. The levels of LH receptors in tumor Leydig cells are only some 1% of that present in normal Leydig cells from adult rats. Tumor Leydig cells grown in hypophysectomized rats had even lower levels of LH receptors; ca. 1/3 of that found in tumors from intact rats. The levels of Prl receptors in the tumor Leydig cells are almost as high as in normal Leydig cells from adult rats. In tumors grown in hypophysectomized rats, the levels of Prl receptors were much lower (ca. 20%) than in tumors from intact or castrated rats. There were great variations in the number of LH and Prl receptors in individual tumors, and there was a positive correlation (r = 0.88; P less than 0.01) between LH and Prl receptors in individual tumors. No differentiation toward a "LH receptor tumor" or "Prl receptor tumor" was observed. Thus, receptors for LH and Prl in tumor cells are qualitatively normal, but the number is greatly (LH) or moderately (Prl) reduced. These receptors in the tumor Leydig cells are stimulated by pituitary hormones.

Developmental pattern and sensitivity to down-regulation of testicular LH receptors in the pig

Testicular receptors for luteinizing hormone (LH) were quantified in 40 pigs between the day of birth and 22 weeks of age. The highest specific binding capacity (fmol hLH bound/mg protein) occurred at about 2--3 weeks of age which coincides with the age when the relative volume of Leydig cells is at a maximum. Significantly lower binding capacity was observed at 7 weeks of age which is the time of maximum Leydig cell regression. hCG was injected intramuscularly to immature (3000 IU, 22 days old) and adult boars (10 000 IU, 30--40 weeks old). Twentyfour h after injection the numbers of available LH receptors were reduced to 6 and 18% of control values, respectively. At this time occupied receptors were at a maximum (90% and 67% of controls, respectively). The total number of LH receptors (available + occupied) was increased 1 h after injection after which a gradual decrease was observed. Three days after hCG administration the total receptor quantities were at a minimum in both immature and adult pigs (59% and 31% of controls, respectively) and returned to control levels 5--7 days after treatment. Thus, pig LH receptors appear to be subjected both 'positive' and 'negative' regulation as previously described in the rat.

Particulate and solubilized LH receptor in the pig and bull testis

Particulate and Triton X-100 solubilized receptors for luteinizing hormone (LH) in the pig and bull testis were studied. In some of the experiments tissue from the rat testis was included for comparison. LH receptors in the bull and pig revealed very similar association and dissociation kinetics, affinity (Kd = 1.2-1.8 x 10(-10) M), stability and physicochemical properties. Binding capacity was higher in the pig (73 fmol/mg protein) than in the rat (33 fmol/mg protein) and bull (17 fmol/mg protein). Hormone binding stabilized the receptor against thermal denaturation and temperature stability decreased upon solubilization. It is concluded that the properties of the testicular LH receptor of the pig and bull are very similar to those previously described from the rat.

Uptake and degradation of desialylated luteinizing hormone by suspended hepatocytes

The uptake and degradation of desialylated human luteinizing hormone (asialo-LH) in suspended hepatocytes have been studied. Asialo-LH was taken up by the asialo-glycoprotein receptor at a rate which was somewhat lower than that of asialo-fetuin. The rate constants and equilibrium binding parameters were similar, but the rate of dissociation of the receptor-ligand complex was higher in the case of asialo-LH. The uptake was influenced by heterogeneity of the asialo-LH preparation. Degradation of endocytosed asialo-LH took place in the lysosomes. After fractionation of the cells by isopycnic centrifugation in a sucrose gradient, partially degraded asialo-LH (precipitable with trichloracetic acid, but not with antibody) was found in the fractions containing endocytic vesicles, but not in the lysosomal fractions, indicating that the proteolysis of asialo-LH was initiated in the endocytic vesicles.

Effects of castration, sex steroids, LHRH and glucocorticoids on LHRH binding in the anterior pituitary of male rats

In the present study we have examined the effects of gonadotrophin releasing hormone (LHRH), sex steroids and glucocorticoids on the binding of LHRH to receptors in the pituitary of male intact and castrated rats. In intact rats, LHRH (10 microgram/day) treatment for 11 days caused a significant increase in LHRH binding, whereas testosterone (500 microgram/day) or oestradiol (50 microgram/day) were inhibitory. 17-hydroxyprogesterone and dexamethasone were without effects. In castrated rats, LHRH caused a marginal decrease in LHRH binding. Much greater inhibition was observed with testosterone and oestradiol. 17-hydroxyprogesterone reduced binding to that of intact controls, whereas dexamethasone was ineffective. When different doses of sex steroids were tested, both oestradiol, testosterone and 5 alpha-dihydrotestosterone inhibited LHRH in a dose-dependent manner. The lowest doses of steroids causing significant inhibition of LHRH binding in castrated animals were 0.5, 50 and 500 microgram/day for oestradiol, 5 alpha-dihydrotestosterone and testosterone, respectively. The present study shows that pituitary receptors for LHRH are regulated both by sex steroids and LHRH itself.

Adenylate cyclase activity in gastric mucosal biopsies and cAMP in gastric juice before and after cimetidine treatment in healthy subjects

Previous studies have revealed augmented parietal call sensitivity to histamine stimulation after cessation of cimetidine treatment in healthy subjects. To elucidate one possible mechanism for this effect, we measured cAMP in gastric mucosa and gastric juice during histamine stimulation in vivo and histamine-stimulated adenylate cyclase activity in vitro in biopsy material obtained by gastroscopy. In eight healthy subjects the cAMP content of gastric corpus mucosal biopsies was measured before, during, and after infusion of 2.5 and 25.6 microgram . kg-1 . h-1 of histamine dihydrochloride. No increase in cAMP content was found. In 10 healthy subjects cAMP secretion into gastric juice was studied before and 36 to 84 h after cessation of 4 weeks' treatment with cimetidine, 1 g/day. No significant increase of cAMP output was found in response to infusion of 2.5 and 25.6 microgram . kg-1 . h-1 of histamine dihydrochloride either before or after the treatment period. Thus histamine does not stimulate cAMP secretion into gastric juice in man. In the same 10 subjects histamine-stimulated adenylate cyclase activity was studied in vitro in biopsy material obtained before and 60 h after cessation of cimetidine treatment. The dose-response curve of the adenylate cyclase activity was not shifted to the left. The results indicate that the augmented parietal cell sensitivity to histamine, seen after stopping cimetidine treatment in healthy subjects, is not due to increased sensitivity of the adenylate cyclase-cAMP system to histamine stimulation.

Evaluation of threatened abortion by human chorionic gonadotropin levels and ultrasonography

To determine the prognostic value of human chorionic gonadotropin (HCG) concentrations in maternal plasma and urine, we studied 104 women with threatened abortion (cases) and 108 women with normal pregnancies and normal serum levels of HCG (controls). Of the 104 cases, 48 were also examined ultrasonically. We concluded that measurements of serum levels of HCG are of more accurate prognostic value than those of urine levels. Low serum levels of HCG indicate a poor prognosis for the pregnancy, as do steady decreases, in repeated measurements, of initially high HCG level. The combination of normal serum levels of HCG and signs of fetal life during ultrasonic examination indicates a very good prognosis for the pregnancy.

Alpha-fetoprotein: a marker for threatened abortion

The role of alpha-fetoprotein (AFP) as a marker for threatened abortion was investigated in 50 patients and compared with the roles of serum human chorionic somatomammotropin (HCS) or human placental lactogen (HPL) and human chorionic gonadotropin (HCG). Of the 50 patients admitted to the hospital with threatened abortion, 30 patients aborted and 20 gave birth to live-born babies. Twenty women aborted within seven days of admission. Eighty-two percent (82%) of the 20 had abnormal AFP values: one third were above the 97.5 percentile and two thirds were below the 2.5 percentile. The AFP values were normal in almost all cases in the group who aborted after seven days. The HCG level in serum was found to be the best indicator of threatened abortion. the AFP and HCS levels were equal indicators of threatened abortion, but were not as reliable as the HCG levels The AFP values are of more diagnostic use than the HCS values, however, because both abnormally low and high AFP levels can indicate an unfavorable course in pregnancy.

Radioimmunossay of secretin in human plasma

A radioimmunoassay is presented which employs 125I-labelled synthetic secretin, antibody against synthetic secretin, and standards prepared from pure natural porcine secretin. Secretin to be measured was extracted into methanol from heparinized plasma containing aprotinin, which together with cysteine hydrochloride was used as stabilizer throughout the assay. With polyethylene glycol separation, a within assay precision of 10% at 17 pmol/1 was found. The between assay precision was 15% at 17 pmol/1 and thelimit of detection 2.5 pmol/1 plasma. Accuracy was 70-85%. The immunoreactive secretin levels in human plasma increased from 4.5+/-0.5 pmol/1 (mean+/-S.E.M.) to 19.5+/-7.5 pmol/1 (mean+/-S.E.M.) after duodenal acidification (n=5). Pancreatic flow rate increased from 0.5+/-0.1 ml/min (mean+/-S.E.M.) to 4.8+/-0.5 ml/min (mean+/-S.E.M.), and bicarbonate output from 9.6+/-1.8 mumol/min (mean+/-S.E.M.) to 268+/-51 mumol/min (mean+/-S.E.M.) after duodenal acidification.

Effect of synthetic luteinizing hormone- and follicle stimulating hormone-releasing hormone (LH-FSH-RH) on serum levels of LH, FSH, thyrotrophin (TSH) and growth hormone (HGH) in normal male subjects

Four normal male subjects received iv injections of synthetic luteinizing hormone- and follicle stimulating hormone-releasing hormone (LH/FSH-RH) in doses of 12.5, 25, 100, 200 and 400 μg, respectively. A dose of 12.5 μg of LH/FSH-RH caused a significant increase in serum FSH, and 25 μg significantly increased the serum LH.

The peak responses occurred 15 to 30 min after the LH/FSH-RH injections in most of the experiments. The increase in the mean maximum serum LH and FSH levels was 2 to 4 fold. There was great variation in response between the subjects, but when tested repeatedly with the same dose of LH/FSH-RH a given individual responded in a consistent manner. The log dose-response curve between LH/FSH-RH and serum LH, and between LH/FSH-RH and serum FSH was approximately linear.

A small but significant (P < 0.05) rise in serum thyrotrophin (TSH) was found after LH/FSH-RH in doses ranging from 25 to 400 μg. There was no significant rise in serum growth hormone (HGH).

On the basis of the present study a standard 100 μg iv LH/FSH-RH test is suggested.