To characterize the mechanisms of insulin resistance in liver cirrhosis (LC), we estimated the peripheral tissue sensitivity and responsiveness to insulin using the euglycemic clamp technique and determined the insulin binding to erythrocytes in patients with compensated LC as well as in patients with non-insulin dependent diabetes mellitus (NIDDM). The insulin dose-response curves of the glucose metabolic clearance rates (MCR) were shifted to the right and downward both in patients with LC and NIDDM, indicating a reduced sensitivity and responsiveness to insulin. In the cirrhotics, MCR at the maximally effective insulin level, an index of insulin responsiveness, was correlated with fasting insulin levels (r=-0.57, P<0.01) and ΣBG in 75gOGTT (r=-0.43, P<0.05), but no correlations were found between them and the diabetics. Although specific insulin bindings to erythrocytes were significantly lower in patients both with LC and NIDDM, Scatchard analysis revealed a significant decrease in the number of insulin receptors in the cirrhotics, and a decrease in the empty-site affinity in the diabetics. These findings suggest that insulin resistance in LC consists of a combination of binding and postbinding defects. The latter defect may be caused by basal hyperinsulinemia and contribute to the development of glucose intolerance. Although binding and postbinding abnormalities are also found in NIDDM, the mechanisms of insulin resistance in LC and NIDDM may be different.
To evaluate the secretory regulation of 19-hydroxyandrostenedione (19-OH-AD), its plasma concentration was measured before and after stimulation and inhibition tests for the ACTH-adrenal axis and the renin-angiotensin system in 50 normal subjects. Basal levels of plasma 19-OH-AD did not correlate with either those of plasma renin activity (PRA) or the plasma aldosterone concentration (PAC), but positively correlated with those of plasma cortisol. Plasma 19-OH-AD was stimulated by 0.25 mg ACTH-(1-24) and was suppressed by 1mg dexamethasone (DEX) as were plasma cortisol and PAC. On the other hand, with 2-h standing alone or iv 40mg furosemide plus 2-h standing, plasma 19-OH-AD and cortisol did not increase but PRA and PAC did. With iv furosemide plus 2-h standing with 3mg DEX pretreatment, plasma 19-OH-AD and cortisol did not respond either, but PRA and PAC increased. With 25mg oral captopril following 1-h standing with 3mg DEX pretreatment, plasma 19-OH-AD and cortisol did not change but PAC decreased. These results indicate that the secretion of 19-OH-AD is mainly under the control of the ACTH-adrenal axis rather than the renin-angiotensin system.
We studied the effect of a specific-competitive inhibitor of the sucrose taste response, p-nitrophenyl-D-glucopyranoside (PNP-Glu) on insulin release and phosphoinositide metabolism in rat pancreatic islets. The α-anomer, but not the β-anomer, of PNP-Glu at a concentration of 5mM inhibited insulin release induced by 10mM glucose. Islets were labeled by exposure for 2h to 10 uCi of myo-[2-3H] inositol solution supplemented with 2.8mM glucose. Forty islets were then incubated in the presence of 10mM LiCl, 1mM inositol and 10mM glucose with or without the anomers of PNP-Glu.[3H] radioactivity in the incubation medium remained significantly greater in the presence of the α-anomer of PNP-Glu than in the presence of glucose alone after 5-and 20-min incubation. The inositol monophosphate levels in the islets incubated with glucose alone were increased more than in the islets with α-anomer. The β-anomer of PNP-Glu did not change either glucose-induced insulin release or phosphoinositide breakdown. A patch-clamp study revealed that neither anomer affected the glucose-dependent ATP-sensitive K+-channels. These results indicate that the anomeric preference for glucose in insulin release in the pancreatic islets is closely associated with phosphoinositide breakdown.
In order to clarify the role of free fatty acid (FFA) in thyroid hormone abnormalities in patients with nonthyroidal illness, thyroid function, FFA, inhibitor of extrathyroidal conversion of T4 to T3 (IEC) and thyroid hormone binding inhibitor (THBI) were studied in 99 patients with various nonthyroidal illnesses including diabetes mellitus (DM)(n=35), liver cirrhosis (LC)(n=33), chronic obstructive pulmonary disease (COPD)(n=17) and chronic heart failure (CHF)(n=14). Patients were divided into three groups based on the level of serum T3: Group I (T3<50ng/dl), Group II (50≤T3<80) and Group III (80≤T3). Serum T4, FT3 and the T3/T4 ratio decreased significantly in the order Group III, Group II and Group I (Group III>II>I). The plasma FFA level was 0.91±0.12mmol/l in Group I (P<0.05, vs. Group III), 0.65±0.06 in Group II and 0.54±0.04 in Group III, respectively. The incidence of positive IEC was 80.0% in Group I (P<0.05, vs. Group III), 53.7% in Group II (P<0.05, vs. Group III) and 34.2% in Group III. However, IEC was not correlated with the serum T3 concentration. The incidence of positive THBI was 80% in Group I (P<0.05, vs. Group III), 68.3% in Group II and 47.4% in Group III, but THBI was not correlated with the serum T4 level. Positive correlations were observed among FFA, IEC and THBI (P<0.001). From the standpoint of the underlying illnesses, DM and LC patients with low T3 had higher plasma FFA and higher incidence of positive IEC and THBI than those with normal T3. In patients with COPD, plasma FFA was not increased and the incidence of positive IEC and THBI was low regardless of their T3 levels. Patients with CHF had high plasma FFA and a high incidence of positive IEC and THBI regardless of their T3 levels. These results suggest that FFA might act as both IEC and THBI, but the degree of the contribution of IEC and THBI to the thyroid hormone abnormalities might differ according to the type underlying illness.
It has been shown that the expression of protooncogenes, c-fos and c-jun, induced by growth factors and hormones plays important roles in cellular proliferation, tissue differentiation and transcription of certain genes. Since gonadotropin stimulates ovarian steroidogenesis and cellular proliferation, we investigated whether gonadotropin affects the expression of c-fos and c-jun genes in rat ovaries. The expression of mRNA coding side chain cleavage enzyme (P450scc), the rate limiting enzyme in ovarian steroidogenesis was also studied. The effect of gonadotropin was examined in female rats whose gonadotrophs were medically ablated by GnRH agonist (TAP-144-SR). After intravenous administration of pregnant mare's serum gonadotropin (PMSG: 30 IU/rat), their ovaries were dissected out at various time intervals and total RNA was extracted. Changes in the levels of c-tbs, c-jun and P450scc mRNAs were determined by Northern blot analysis. The levels of c-tbs and c-jun mRNAs increased rapidly and transiently with the peak levels at 15 min after PMSG administration. The levels of both mRNAs were decreased by 30 to 60min. On the other hand, the levels of P450scc mRNA started to increase 60min after PMSG. These results indicate that gonadotropin-induced increase in the expression of c-fos and c-jun genes may play important roles in mediating the action of gonadotropin on the ovaries.
The relationship between type I iodothyronine 5'-monodeiodinase (5'-MD) and protein disulphide isomerase (PDI) was investigated by using a synthetic 18-amino acid peptide (LAP475c), which corresponds to the sequence of amino acids at position 373-390 of PDI including its active site, and anti-LAP475c antibody. Western blot analysis revealed that our anti-LAP475c antibody was highly specific for 57K protein in solubilized rat liver microsomal protein (SRLMP) that corresponded to PDI. Anti-LAP475c IgG (1: 100 dilution) precipitated 46% of 5'-MD. These data suggest that PDI may play a regulatory role in the 5'-monodeiodination reaction.
In order to study the mode of action of TRH and sulpiride in man, we administered TRH (500μg, iv) and sulpiride (DA D2 receptor antagonist, 100 mg, im) simultaneously to 6 normal females (20-21 yr). Normal females showed significantly greater PRL increments and AUC in response to the combined administration compared to a single administration of each agent (P<0.05-0.01), while the increment and AUC in response to the combination did not exceed the sum of those responses to a single administration. In contrast, the combined administration of TRH and sulpiride did not elicit an enhanced response of plasma TSH. These results indicate that the sites of action of TRH and sulpiride might be different from each other, and these agents work additively with no interaction in human lactotrophs.
In this paper, we report a 49-year-old female with subacute thyroiditis who had thyroidstimulating antibodies (TSAb) and thyroid-stimulation-blocking antibodies (TSBAb) in serum. Although she was in the thyrotoxic phase and TSH was suppressed in May, 1990, her radioactive iodine uptake (RAIU) was not suppressed (35.5%) and a thyroid scan disclosed a diffuse goiter with no defect. Serum assays revealed the presence of TSAb, but TSBAb were negative. In August, 1990, the right lobe became undetectable by thyroid scan when the RAIU was 20.7% with the TSH level remaining suppressed. At that time, TSAb were negative, while TSBAb were positive. When the RAIU was 31.1% in October, 1990, both thyroid lobes became visible and the TSH level was normalized. TSBAb became negative, and although TSAb reappeared it later became undetectable. These results indicate that the changes in the patient's thyroid scan and RAIU were attributable to the presence of TSAb.
The glucocorticoid receptor is a member of the steroid and thyroid hormone receptor superfamily and acts as a ligand-activated transcription factor. To reconstitute the molecular mechanisms underlying the cellular response to soluble receptor ligands, we have exploited a cell-free system that exhibits glucocorticoid-induced activationof the latent cytosolic glucocorticoid receptor to an active DNA-binding species. We demonstrate here that cytosol from a rat hepatoma cell, M1. 19, contains glucocorticoid receptor-specific immunoreactivities and target DNA-binding activities. Moreover, specific DNA-binding activities of M1.19 cytosol were dose-dependently induced by dexamethasone treatment, and linearly correlated with the hormonal induction of chloramphenicol acetyltransferase activity at the corresponding concentrations. These results indicate that the cytosolic glucocorticoid receptor could be converted in a DNA-binding form under cell-free conditions and the ligand appears to play a crucial role in the direct control of the level of functional activity of a given ligand-receptor complex.
To determine the importance of adrenal steroid in the effects of interleukin-1, we investigated changes in the number of islet cells reactive toward antiserum to insulin (anti-Ins) by intraperitonealadministration of recombinant human interleukin-1β(IL-1) in intact and adrenalectomized (ADX) rats. IL-1 significantly reduced serum insulin levels in ADX rats only, while it similarly decreased plasma glucose levels. In intact rats, IL-1 did not affect the number of islet cells reactive to anti-Ins, although cytoplasmic immunostaining tended to be reduced by IL-1 treatment. Only adrenalectomy decreased the number of islet cells immunostained by anti-Ins. Furthermore, IL-1 treatment significantly reduced the number of islet cells reactive to anti-Ins in ADX rats. The present study immunohistochemically supported our working hypothesis that the withdrawal of adrenal steroids by adrenalectomy enhances the islet cell sensitivity to exogenous administration of IL-1.
Abstract. Changes in the membrane potential and the intracellular Ca2+ concentration ([Ca2+]i) caused by somatostatin (SRIF) were simultaneously measured in human GH-producing pituitary tumor cells, by means of the nystatin-perforated whole cell clamp technique and Fura-2 AM. An application of 10-8M SRIF hyperpolarized the membrane and arrested Ca2+-dependent spontaneous action potentials.[Ca2+]i concurrently decreased during membrane hyperpolarization. When the membrane potential was clamped below the threshold for voltage-gated Ca2+ channels, [Ca2+]i decreased and SRIF did not further reduce [Ca2+]i. In cells which did not show spontaneous action potentials, SRIF hyperpolarized the membrane but it affected [Ca2+]i little. From these results it was concluded that the reduction in [Ca2+]i caused by SRIF was ascribed to the decrease in Ca2+ influx through voltage-gated channels during membrane hyperpolarization. The effect of SRIF on the voltage-gated Ca2+ channel current was also examined under the perforated whole cell clamp. SRIF (10-8M) inhibited the Ca2+ channel current to 80.8±15.4%(n=5) of the control. Because SRIF-induced inhibition of the voltage-gated Ca2+ channel current was not prominent, it was considered that membrane hyperpolarization is the major cause of the reduction in [Ca2+]i in human GH-producing cells.
A 59-year-old woman with primary hyperparathyroidism was found to have a parathyroid adenoma behind the left clavicle. Preoperatively, it appeared as a hypoechoic mass on ultrasonography, as a hot nodule on thallium scintigraphy, and as a high signal on T2-weighted magnetic resonance imaging. Histological, immunohistochemical and ultrastructural studies of the surgically resected tumor revealed a parathyroid adenoma composed mainly of oxyphil cells with production of a parathyroid hormone. Moreover, a multilocular lesion of lymphangiectasia was contained. Hypercalcemia was alleviated postoperatively. These observations corroborated a functioning parathyroid oxyphil cell adenoma. This is the first case report of functioning oxyphil cell adenoma of the parathyroid gland with lymphangiectasia in Japan.
Insulin-like growth factor I (IGF-I) levels in urine were measured in adults using specific RIA after extraction with acid-ammonium sulfate. Mean (±SD) total urine IGF-I values were 267.9±112.9ng/day and 167.8±73.2ng/g creatinine (Cr) in 17 normal young adults. There was a positive correlation (r=0.785, P<0.001) between IGF-I values in early morning urine and those of 24h urine when they were corrected by urinary Cr. IGF-I values in early morning urine were ranged from 60 to 1, 100ng/gCr with a mean value of 309.6ng/gCr in 178 normal adults aged 21-80 yr. There was a consistent trend towards higher urinary IGF-I values in males during aging and this trend did not reach statistical significance until the sixth and seventh decades. There was a positive correlation (r=0.465, P<0.005) between urinary IGF-I values and age in males but not in females. Although urinary IGF-I values were higher in females than in males of the second and third decades, no sex difference was found in older adults. Urinary IGF-I values were correlated reversely with 24h Cr clearance (CCr) and positively with urinary β2-microglobulin (β2-MG) levels in patients with renal dysfunction. These findings indicate that urinary IGF-I levels are influenced by age, sex and renal function in adults.
Whether or not 1-desamino-8-D-arginine-vasopressin (DDAVP) reduces blood pressure or affects the release of arginine vasopressin (AVP) and renin is controversial, although evidence suggests AVP and renin are important in maintaining blood pressure during hemorrhage. We therefore investigated the effect of DDAVP on endogenous release of AVP and renin and on blood pressure during hemorrhage in dogs.In the control group the hemorrhage was performed at a rate of 0.4ml·kg-1·Emin-1 for 40min from the femoral artery. The plasma AVP concentration and renin activity (PRA) increased progressively in response to the hemorrhage, from 7.5±0.5 to 40.3±7.3pg·ml-1, and from 11.8±1.5 to 20.5±4.2 ng·ml-1·h-1, respectively, while blood pressure decreased slightly. In the DDAVP group, intravenous infusion of DDAVP (2.5ng·kg-1·min-1 for 40min) and hemorrhage were simultaneously performed. The plasma DDAVP concentration increased progressively to 218±21.0pg·ml-1. There was no significant difference, however, between the control and DDAVP groups in the response of AVP, PRA and blood pressure. The results suggested that DDAVP may not affect the release of AVP and renin or blood pressure during hemorrhage.