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B C Nisula

Publications and source records attributed to B C Nisula.

At least 55 records · Page 3Linked to original sources
PubMed1986

Inactivation of follicle-stimulating hormone by a factor in a bovine serum albumin preparation.

Bovine serum albumin (BSA) preparations are commonly employed as "carrier" or "protective" proteins in the solutions used to dissolve gonadotropin preparations. The present report describes a BSA preparation that was found to contain a factor that inactivated follicle-stimulating hormone (FSH). Four different BSA preparations (designated BSA1, BSA2a, BSA2b, BSA3) were studied. The FSH preparation (NIH-FSH-S16) was dissolved in 0.15 M NaCl, containing the various BSA preparations. The FSH solutions were injected subcutaneously, twice daily, for 5 days into hypophysectomized immature female rats bearing estrogen capsules. Twenty-four hours after the last injection, the rats were decapitated, and the ovaries were removed, trimmed and weighed. The FSH preparation produced ovarian weight gain when BSA1, BSA2b, or BSA3 was used, but not when BSA2a was used in the vehicle. In animals injected with the FSH dissolved in BSA1 vehicle and injected at a separate site with BSA2a solution, the FSH preparation was fully active, which indicates that contact of the BSA2a preparation with FSH was required for the inactivating factor to be operant. Indeed, after incubation in BSA2a solution, the radiolabeled FSH preparation exhibited a slight decrease in apparent molecular size when chromatographed on a Sephadex G-100 column. This result suggests that the BSA2a preparation contained a factor that may have inhibited FSH by degrading it.

Animals↗
PubMed1986

Renal metabolism of the beta-subunit of human choriogonadotropin in the rat.

We analyzed the immunoreactive renal metabolites of the beta-subunit moieties of unlabeled highly purified hCG, hCG beta, and desialylated hCG (as-hCG) in rats by RIA and Sephadex G-100 chromatography. Infusions of hCG beta, as-hCG, or intact hCG resulted in accumulation in the kidney of a large quantity of small mol wt peptides lacking the immunological determinants of the carboxy-terminal peptide (CTP) of the beta-subunit. In the case of as-hCG, renal accumulation of these beta-core fragments was greatly enhanced when as-hCG binding to hepatic galactose receptors was inhibited by infusion of as-fetuin. The beta-core fragments in kidney had the same immunological and G-100 chromatographic characteristics as beta-core fragments in liver, suggesting similar intracellular catabolic mechanisms in these tissues. The kinetics of beta-core fragment turnover in kidney were studied after injection of hCG beta, which is cleared from the circulation within 1 h. Loss of beta CTP immunoreactivity was the initial event in hCB beta catabolism by the kidney; most of this process occurred between 7 and 30 min after injection. This was followed by a gradual reduction of the size of accumulated hCG beta metabolites over the next 60 min. The beta-core fragments that accumulated had a Kav of approximately 0.57 and a very slow degradation rate over the next 5 h (half-life greater than 6 h). Chromatographic analysis of urine obtained 6 h after beginning a continuous infusion of hCG, hCG beta, or as-hCG displayed in each case a major peak corresponding to the infused molecule, apparently intact, and a minor peak of beta CTP immunoreactivity of small mol wt. Relative to the beta CTP fragments apparent in urine, there were few beta-core fragments. These data indicate that separate fates exist for immunoreactive fragments generated by hCG beta metabolism in the rat kidney. One appears to be intracellular and similar to the liver pathway of as-hCG degradation in that it leads to the formation of long-lived beta-core fragments. The other takes place within ready access to the urinary compartment and leads to the accumulation in urine of beta-CTP fragments.

Animals↗
PubMed1986

Inhibition of follicle-stimulating hormone/diethylstilbestrol-stimulated ovarian growth by extracts of pregnancy urine.

We devised an in vivo biological assay for ovarian growth inhibiting activity to examine extracts of human pregnancy urine for the presence of ovarian growth inhibiting factor. Diethylstilbestrol (DES) capsules were implanted sc in immature hypophysectomized female rats; FSH was injected sc with or without test substance for 5 days. Rats with unstimulated ovaries were implanted with blank capsules and given the vehicle without FSH. Twenty four hours after the last injection, the ovaries were removed and weighed. The ovarian growth inhibition of the ovarian weight gain achieved in rats treated with DES and FSH. Crude commercial human CG (hCG) preparations, extracted from pregnancy urine, were chromatographed on Sephadex G-100, and the fractions were tested for ovarian growth inhibiting activity. The peak of ovarian growth inhibiting activity was found in fractions eluting from the column in the mol wt range of 12,000-20,000. Ovarian growth inhibiting activity was heat sensitive, not extracted by ether, and precipitated by acetone. Ovarian growth inhibiting activity was stable in acid at pH 2, but was inactivated by digestion with trypsin. The ovarian growth inhibiting activity was purified by chromatography on Concanavalin A-Sepharose and diethylaminoethyl-Sephacel. The active material contained hCG alpha, hCG beta, and beta-carboxyterminal peptide-immunoreactivity and its inhibiting activity could be removed from solution by immunoadsorption with antisera specific for hCG beta. The ovarian growth inhibiting activity was further purified on an anti-hCG alpha-immunoglobulin G affinity column. The activity was eluted from the affinity column at low pH, and eluted material contained all of the immunodeterminants of hCG. Virtually identical dose-response curves of ovarian inhibition were obtained using equivalent doses of beta-carboxyterminal peptide immunoreactivity of purified inhibitor and purified hCG (CR123). The inhibiting activity reached plateau of 80-90% at doses of 50-100 ng hCG/rat. Upon rechromatography on Sephadex G-100, the ovarian growth activity that was pooled from fractions corresponding to the 12,000-20,000 mol wt range was recovered in fractions corresponding to the elution position of hCG. We conclude that the low mol wt inhibiting activity observed in the crude pregnancy extracts is due to hCG and that hCG is a very potent inhibitor of FSH/DES stimulation of ovarian growth.

Acetone↗
PubMed1986

Deficient nocturnal surge of thyrotropin in central hypothyroidism.

In normal individuals, serum TSH concentrations have a circadian pattern characterized by a nocturnal surge which begins in the late afternoon and reaches its peak after midnight. We assessed the nocturnal surge of TSH in 16 patients with pituitary and/or hypothalamic diseases, 6 of whom were judged to be hypothyroid. To assess the magnitude of the nocturnal surge in individual patients, TSH was measured in 5 serum samples obtained during the normal time of the TSH nadir in the late afternoon and in 5 samples obtained during the normal time of the peak of serum TSH after midnight. A significant nocturnal surge of TSH was defined as a significantly greater mean nighttime TSH level than the mean daytime TSH concentration. The nocturnal TSH surge was absent in the 6 patients with central hypothyroidism, while it was present in the 10 euthyroid patients with central lesions. In 6 hypothyroid patients who did not have pituitary or hypothalamic lesions, the nocturnal TSH surge was intact, indicating that hypothyroidism per se does not account for the deficient nocturnal TSH surge in central hypothyroidism. We conclude that central hypothyroidism is characterized by a deficient nocturnal surge of TSH, and accordingly, we suggest that evaluation of the circadian pattern of TSH may be a useful adjunct in making the diagnosis of hypothyroidism in patients with diseases involving the pituitary or hypothalamus.

Adolescent↗
PubMed1985

Preparation of steroid radioligands for ultrafiltration assays by a solid-phase transport globulin method using concanavalin A-Sepharose.

Concanavalin A-Sepharose (Con A-Sepharose) was applied to separate non-protein-bound and albumin-bound radioactive impurities from steroid radioligands. Con A-Sepharose gel, plasma, and steroid radioligand were mixed, incubated, and then washed with buffer. This method was compared with an affinity diafiltration method which separates non-protein-bound radioactive impurities with a filter membrane. 3H-Water and 3H-estrone sulfate, chosen to serve as molecules representative of non-protein-bound and albumin-bound impurities, were removed quite effectively by the Con A-Sepharose method, while 85% of 3H-estrone sulfate could not be removed by the diafiltration method. Plasma unbound cortisol (F) and testosterone (T) values determined by ultrafiltration using 3H-F and 3H-T prepared by the Con A-Sepharose method were significantly lower than those determined using the radioligands unprocessed or prepared by the diafiltration method. The whole procedure of the Con A-Sepharose method takes only 3-4 hours. This method is a simple, rapid, and effective technique for preparation of steroid radioligands for plasma protein binding studies.

Female↗
PubMed1985

Variations in the oligosaccharides on free and combined alpha-subunits of human choriogonadotropin in pregnancy.

The glycoprotein hormone hCG and a free alpha-subunit are secreted by trophoblastic cells during pregnancy. We have purified the alpha-subunit of hCG and the free alpha-subunit population from pregnancy urine. Dissociation of hCG with 10 M urea at 37 C, followed by chromatography on DEAE-Sephacel, resulted in separation of alpha- from beta-subunit, as hCG alpha does not bind to DEAE in the presence of urea, while beta-subunit does bind. Similar treatment of the free alpha population resulted in fractionation into two populations, a nonbinding fraction of free alpha and a population which was retained by DEAE in the presence of urea (free alpha 2). The three populations, hCG alpha, free alpha, and free alpha 2, were further purified by affinity chromatography using anti-alpha antisera linked to Sepharose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the preparations showed that hCG alpha consisted of a single component with an apparent mol wt of 22,000, while free alpha and free alpha 2 consisted of multiple components. Radioactive labeling of sialic acid by limited periodate oxidation and NaB[3H]4 reduction resulted in a higher specific activity for free alpha than for hCG alpha, suggesting that free alpha contains more sialic acid per immunoreactive molecule than does alpha dissociated from hCG. [3H]hCG alpha, but not 3H-labeled free alpha, was able to combine with native hCG beta-subunit. The oligosaccharide moieties were released from the different labeled subunits by alkaline hydrolysis and then compared with respect to Concanavalin A (ConA)-binding and DEAE-binding properties. Most of the oligosaccharides from dissociated hCG alpha bound to ConA-Sepharose (72%), while less material from free alpha (40%) and even less from free alpha 2 (25%) were capable of binding to ConA. DEAE chromatography of the oligosaccharides suggested that hCG alpha contained primarily monosialylated forms (greater than 60%), while free alpha and alpha 2 contained primarily (greater than 70%) di- and trisialylated forms. Thus, the ConA and DEAE binding data indicated that the oligosaccharide contents of free alpha and free alpha 2 were quite different from that of hCG alpha. These results also suggest that some of the oligosaccharide structures contained on hCG alpha and most of those on free alpha and free alpha 2 differ substantially from the structures that have been previously described.

Carbohydrate Sequence↗
PubMed1985

Successful treatment of Cushing's syndrome with the glucocorticoid antagonist RU 486.

A patient with Cushing's syndrome due to ectopic ACTH secretion was treated successfully with the new glucocorticoid antagonist RU 486 [17 beta-hydroxy-11 beta-(4-dimethylamino phenyl) 17 alpha-(1-propynyl)estra-4,9-dien-3-one]. This compound is a 19-nor steroid with substitutions at positions C11 and C17 which antagonizes cortisol action competitively at the receptor level. Oral RU 486 was given in increasing doses of 5, 10, 15, and 20 mg/kg . day for a 9-week period. Treatment efficacy was monitored by assessment of clinical status and by measuring several glucocorticoid-sensitive variables, including fasting blood sugar, blood sugar 120 min after oral glucose administration, and plasma concentrations of TSH, corticosteroid-binding globulin, LH, testosterone-estradiol-binding globulin, and total and free testosterone. With therapy, the somatic features of Cushing's syndrome (buffalo hump, central obesity, and moon facies) ameliorated, mean arterial blood pressure normalized, suicidal depression resolved, and libido returned. All biochemical glucocorticoid-sensitive parameters normalized. No side-effects of drug toxicity were observed. We conclude that RU 486 may provide a safe, well tolerated, and effective medical treatment for hypercortisolism.

Adrenocorticotropic Hormone↗
PubMed1985

Bioavailability of albumin-bound testosterone.

The unbound fraction of plasma testosterone (T) can freely enter tissues, whereas the bioavailability of the albumin-bound T is controversial. A clinical observation in hirsute women receiving spironolactone suggested an experimental paradigm to test the effect of albumin binding on T bioavailability. We found an increase in the non-T-estrogen-binding globulin-bound fraction of plasma T in women from 24.1 +/- 3.9% to 42.0 +/- 8.1% (+/-SEM) while they received spironolactone. Computer modeling indicated that the absolute increase in the albumin-bound T concentration would be about 22.4-fold greater than that in the unbound T concentration (the ratio of albumin-bound to free T remaining virtually constant) because of the binding of T to albumin. We reasoned that the addition of graded amounts of spironolactone and its metabolites to plasma would provide a means to increase the albumin-bound T concentration appreciably. We evaluated the biological effects of this perturbation of T transport by spironolactone and its metabolites in a bioassay system using the Oldendorf technique. Bioavailable T increased proportionately with increments in free and albumin-bound T (r = 0.85; P less than 0.01). A major portion of the albumin-bound T (i.e. 55%) entered tissues under all conditions; the amount that was bioavailable vastly exceeded the amount of T that was unbound in the injected samples. An index of the amount of bioavailable T can be determined using the ammonium sulfate precipitation technique, as the percentage of non-T-estrogen-binding globulin-bound T in vitro correlated well with T bioavailability in vitro (r = 0.86; P less than 0.01). These studies support the conclusion that albumin-bound T is biologically important.

Adult↗
PubMed1985

Measuring early pregnancy loss: laboratory and field methods.

We intensively studied 30 women attempting pregnancy in order to lay groundwork for larger studies of early pregnancy loss. These women collected first morning urine specimens for up to 6 months after discontinuing use of birth control. Urine specimens were successfully collected for 98% of the woman-days in the study. Three assays for human chorionic gonadotropin (hCG) were performed on each urine specimen. An immunoradiometric assay (IRMA) specific to the carboxyterminal peptide of the hCG beta-chain proved to be more sensitive and more specific than two radioimmunoassays (RIAs). Using the IRMA, we found four cases in which hCG rose and fell over successive days, consistent with early pregnancy loss. For three of these four cases, the level of hCG was too low to be detectable with the RIAs. Among the control group of five women with tubal ligations, there was no detectable hCG above threshold with the IRMA. Thus, the enhanced sensitivity and specificity of the IRMA allows very early pregnancy losses to be identified that would otherwise be undetectable. Furthermore, its effectiveness with small quantities of first morning urine makes the IRMA a useful tool for epidemiologic studies.

Abortion, Spontaneous↗
PubMed1984

Plasma testosterone transport in primates.

All primate species, including Old and New World primates and prosimians have a plasma testosterone-estradiol binding globulin (TeBG), which is a glycoprotein and has a similar mobility in polyacrylamide gel electrophoresis. In New World primates the TeBG binding capacity for [3H]testosterone was higher and its affinity lower than in Old World primates. These changes were associated with high unbound plasma testosterone concentrations in these species. Binding parameters of TeBG in prosimian species varied markedly. Thus, in primate evolution TeBG was conserved despite marked differences in binding characteristics. In New World primates changes are associated with high total and unbound testosterone, a finding concordant with alterations of other steroid hormones concentration in these species with "generalized steroid hormone resistance".

Animals↗
PubMed1984

Relevance of the low and high affinity thyrotropin-binding sites of human thyroid membranes to the stimulation of adenylate cyclase.

TSH is known to interact on thyroid membranes with two classes of binding sites that differ in affinity and capacity. To assess the relevance of the class of TSH-binding sites characterized by low affinity and high capacity to the stimulation of adenylate cyclase, we studied the interactions of desialylated hCG (as-hCG) and its beta-subunit (as-hCG beta) with human thyroid membranes. In low ionic strength buffer, pH 7.8, where both classes of sites are operant, as-hCG fully inhibited and as-hCG beta partially inhibited [125I] bovine (b) TSH binding. Scatchard analysis of the [125I]bTSH binding inhibition curve in the presence of 1.0 X 10(-5) M as-hCG beta clearly indicated that as-hCG beta interacted only with the low affinity class of binding sites, leaving the high affinity class unaffected. In the presence of 140 mM NaCl, [125I]bTSH interacted predominantly with the high affinity class of binding sites; as-hCG fully inhibited [125I]bTSH binding to this class of sites, whereas as-hCG beta displayed essentially no interaction. Scatchard analysis of [125I]as-hCG beta binding to human thyroid membranes in low ionic strength buffer revealed a single apparent class of sites with low affinity (Kd = approximately 1.0 X 10(-6) M) and high capacity (Q = approximately 300 pmol/mg membrane protein). The bTSH preparation (Thytropar) showed a 10-fold greater binding inhibition potency at these sites than either the as-hCG or the as-hCG beta preparation, in keeping with the inference that as-hCG beta interacts with the low affinity class of TSH-binding sites. At a concentration more than 3 times that necessary to inhibit TSH binding to the low affinity class of sites, the as-hCG beta molecule neither stimulated adenylate cyclase nor inhibited the ability of TSH to do so. In contrast, the as-hCG molecule, which interacts with both classes of TSH-binding sites, fully inhibited TSH stimulation of adenylate cyclase. We conclude that the low affinity class of TSH-binding sites is not the class of sites through which TSH stimulates adenylate cyclase, and that this role is best ascribed to the high affinity class of TSH-binding sites.

Adenylyl Cyclases↗
PubMed1984

Plasma cortisol transport and primate evolution.

Primates have diverged into three major evolutionary groups: prosimians, Old World primates, and New World primates; the last group is distinguished by high circulating cortisol concentrations and resistance to the action of glucocorticoids. We have studied a large spectrum of primate species within these groups to characterize the phylogenetic relationships of cortisol-binding globulin (CBG) among them. The CBG in each species was found to be glycosylated, as judged from lectin interactions, and to exhibit an electrophoretic mobility similar to that of human CBG. Although the CBG affinity for cortisol differed among species, the effects of changes in temperature on the CBG affinity were similar. Strikingly, the CBG-binding capacity of plasma in the New World primates was 1/10th to 1/100th those in the Old World primates and prosimians, while the CBG-binding affinity for cortisol was lower. The reduced capacity and affinity of CBG result in a markedly higher fraction of unbound plasma cortisol in the New World primates than in the Old World primates or the prosimian species examined. This evolutionary pattern of CBG may be a compensatory mechanism for the target organ resistance to glucocorticoids that characterizes the New World monkeys.

Animals↗
PubMed1984

Evidence that desialylation and uptake by hepatic receptors for galactose-terminated glycoproteins are immaterial to the metabolism of human choriogonadotropin in the rat.

It is widely known that removal of sialic acid from the carbohydrate chains of glycoproteins in vitro drastically reduces their survival time in the circulation; however, it is not known whether desialylation plays a significant role in the metabolism of sialylated serum glycoproteins in vivo. We have studied the metabolism of hCG and desialylated hCG (as-hCG) in rat serum and liver in vivo to assess this putative metabolic pathway for glycoprotein hormones. A single injection of as-hCG into rats was followed by its rapid removal from the circulation, principally by the liver, and its degradation into fragments of the hCG beta-subunit that lacked the carboxy-terminal peptide antigenic determinant. Continuous infusion of desialylated fetuin (as-fetuin) at a high rate along with as-hCG dramatically reduced accumulation of the beta-subunit fragments in liver and resulted in increased serum levels of as-hCG. Consequently, the MCR of as-hCG was reduced from 301 +/- 10.3 ml/h (mean +/- SE) to 13.4 +/- 1.15 ml/h by infusion of as-fetuin, which is known to compete for hepatic receptors for galactose-terminated glycoproteins. In contrast, coinfusion of as-fetuin with hCG did not influence the MCR of hCG. Furthermore, there was no serum accumulation of hCG desialylated in its hCG beta carboxy-terminal portion, with or without as-fetuin, and the quantity and pattern of immunoreactive hCG products in liver homogenate were not affected by coinfusion of as-fetuin with hCG. Thus, blockade of hepatic receptors for galactose-terminated glycoproteins did not impede hCG turnover in the circulation, impair hepatic catabolism of hCG, or lead to the accumulation of desialylated products of hCG in plasma. These data indicate that in the rat, there is negligible catabolism of glycoproteins, such as hCG, by a pathway that involves peripheral desialylation and subsequent hepatic uptake via receptors for galactose-terminated glycoproteins.

Animals↗
PubMed1984

Radioimmunoassay of human thyrotropin: analytical and clinical developments.

Recent modifications of the radioimmunoassay systems for TSH have greatly extended the clinical utility of the measurement of this hormone, so that its use is no longer limited to the diagnosis of primary hypothyroidism. The newer assays provide improved sensitivity and specificity, such that it is now possible to distinguish TSH levels that are within the normal range from those that are suppressed, e.g., in thyrotoxicosis. New vistas of clinical applications are being revealed as we improve our understanding of human thyroid physiology and pathophysiology. It is the purpose of this communication to summarize information about the improved TSH radioimmunoassay, to demonstrate the new observations available regarding TSH concentrations in various normal and diseased conditions, and finally, to illustrate the various ways in which the assay provides more accurate guidance in the clinical diagnosis and management of thyroid and nonthyroid disease.

Adolescent↗
PubMed1984

Metabolism, distribution and excretion of purified human chorionic gonadotropin and its subunits in man.

We have characterized the distribution, metabolism and excretion of hCG and its subunits in normal human subjects. The initial apparent volume of distribution was the same for hCG, hCG beta, and hCG alpha. Their disappearance curves fit a two-component exponential model, and calculations indicated that both the rapid and slow phase half-times of hCG are approximately 10-fold greater than those of hCG beta and 30-fold greater than those of hCG alpha. Despite the more rapid metabolic clearance rates of the subunits, their renal clearance is 2- to 3-fold less than that of hCG. Thus, renal clearance accounts for less than 1% of the metabolic disposal of the subunits, whereas it represents a major fraction (20-25%) of the metabolic disposal of hCG. After injection of the isolated beta subunit of hCG, two forms were excreted in the urine. One was intact hCG beta and the other was a discrete fragment of the hCG beta which appears to lack the hCG beta carboxyterminal peptide immunologic determinant; we have termed this later material an hCG beta core fragment.

Chorionic Gonadotropin↗
PubMed1983

Immunosuppressive activity of human chorionic gonadotrophin preparations in vivo: evidence for gonadal dependence.

Human chorionic gonadotrophin preparations (hCG), when injected ip daily for 4 days, suppress the delayed-type hypersensitivity (DTH) response of mice to sheep red blood cells. Preparations of crude hCG, purified hCG subunits, and hCG that was formed by recombining the purified subunits showed immunosuppressive activity in accord with their gonadotrophic activity. The immunosuppressive effects in male and female mice were comparable. However, removal of the gonads completely abrogated the immunosuppressive activity of hCG in both males and females, suggesting that the effect of hCG is mediated by a factor released from the gonads. We conclude that the hCG molecule itself exhibits immunosuppressive activity in vivo in both male and female mice and that the gonads are required for the expression of this activity.

Animals↗
PubMed1983

Extended clinical utility of a sensitive and reliable radioimmunoassay of thyroid-stimulating hormone.

We have developed a radioimmunoassay for thyroid-stimulating hormone (TSH) that is sufficiently sensitive to permit reliable measurement of subnormal serum TSH levels. We report our evaluation of the utility of this radioimmunoassay in the diagnosis and management of thyroid disease. In 59 normal subjects, the mean serum TSH level was 1.49 +/- 0.10 microU/ml (mean +/- SEM) with the range 0.5 to 4.5 microU/ml. In patients without pituitary-hypothalamic lesions, the serum TSH level accurately reflected thyroid status, being subnormal in 29 hyperthyroid patients, supranormal in 26 hypothyroid patients, and normal in 31 euthyroid patients being treated for nonthyroid conditions. In patients being treated for either hyperthyroidism or hypothyroidism, the serum TSH level appeared to be a sensitive indicator of thyroid status, and its return to normal appeared to be a useful therapeutic criterion. We conclude that improving the sensitivtity and reliability of the serum TSH radioimmunoassay greatly extends its clinical applications.

Adolescent↗