Insulin sensitivity, insulin secretion, and glucose effectiveness in subjects with impaired glucose tolerance: a minimal model analysis

The aim of the present study was to estimate insulin secretion, insulin sensitivity (SI), and glucose effectiveness (SG) in non-obese Japanese subjects with impaired glucose tolerance (IGT). Ten IGT subjects (five men, five women) and 15 normal-tolerance subjects (seven men, eight women) without a family history of diabetes were studied. They underwent a modified frequently sampled intravenous glucose tolerance test (FSIGT); glucose (300 mg/kg body weight) was administered, and insulin (20 mU/kg over 5 minutes) was infused from 20 to 25 minutes after the administration of glucose. SI and SG were estimated by Bergman's minimal model method. No significant difference was observed in body mass index ([BMI] 22.1 +/- 0.8 v 21.1 +/- 0.5 kg/m2), fasting plasma glucose (5.19 +/- 0.18 v 5.07 +/- 0.11 mmol/L), and insulin levels (50.7 +/- 7.3 v 45.2 +/- 4.5 pmol/L) of subjects with IGT and normal controls. The glucose disappearance rate (KG) was significantly lower in subjects with IGT than in normal-tolerance subjects (1.57 +/- 0.20 v 2.09 +/- 0.15%/min, P < .05). Pancreatic insulin secretion expressed as the integrated area of plasma insulin above the basal level during the first 20 minutes was lower in IGT subjects (2,556 +/- 572 pmol/L x min) than in normal-tolerance subjects (4,957 +/- 800 pmol/L x min, P < .05). SI was not statistically different between the two groups (0.84 +/- 0.13 x 10(-4) v 1.14 +/- 0.15 x 10(-4).min-1.pmol/L-1). However, SG was significantly lower in subjects with IGT than in normal controls (0.013 +/- 0.002 v 0.023 +/- 0.002 min-1, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of somatostatin receptor subtypes and an implication for the efficacy of somatostatin analogue SMS 201-995 in treatment of human endocrine tumors

The presence of somatostatin receptors has been demonstrated in various endocrine tumors as well as in normal tissues. We recently have cloned five human somatostatin receptor subtypes (SSTR1-SSTR5). These mRNAs are expressed in a tissue-specific manner. In this study, we have determined the somatostatin receptor subtypes expressed in various endocrine tumors using a reverse transcriptase polymerase chain reaction method. In two cases of glucagonoma and its metastatic lymph nodes in one case, all the SSTR subtype mRNAs except SSTR5 mRNA were expressed. In four cases of insulinoma, SSTR1 and SSTR4 mRNAs were detected, but SSTR2 mRNA was not detected in one case and SSTR3 mRNA was not detected in two cases, indicating a heterogeneous expression of SSTR subtypes in insulinomas. Interestingly, SSTR3 mRNA, which is highly expressed in rat pancreatic islets, is not expressed in normal human pancreatic islets, while SSTR1, SSTR2, and SSTR4 mRNAs are expressed. In three cases of pheochromocytoma, SSTR1 and SSTR2 mRNAs were detected, showing an expression pattern identical to that of normal adrenal gland. In a carcinoid, SSTR1 and SSTR4 mRNAs were detected. We have also found that human SSTR2 shows a high affinity for SMS 201-995, which has been used clinically for the treatment of endocrine tumors. Since SMS 201-995 was effective in the treatment of a patient with glucagonoma in which SSTR2 mRNA was present, but had no effect in a patient with carcinoid in which SSTR2 mRNA was not detected, this study suggests that the efficacy of SMS 201-995 may depend, at least in part, on the expression of SSTR2 in tumors.

Clearance mechanisms of atrial and brain natriuretic peptides in rats

To assess clearance mechanisms of atrial and brain natriuretic peptides in the circulation, we examined the effects of a neutral endopeptidase (NEP) inhibitor and a clearance receptor ligand on plasma concentrations of the peptides in normal rats. Plasma concentrations of endogenous alpha-rat atrial natriuretic peptide (alpha-rANP) were not significantly elevated by intravenous infusion of a NEP inhibitor, phosphoramidon, but were elevated threefold by intravenous infusion of a clearance receptor ligand, des(Gln18-Gly22)-rANP(4-23)-NH2 [C-ANF(4-23)]. On the other hand, the clearance of alpha-rANP given intravenously at the pharmacological dose, 600 pmol/min/kg for 2 min, was decreased to one-third by the administration of phosphoramidon, although the administration of C-ANF(4-23) did not significantly decrease the clearance. The clearance of rat brain natriuretic peptide (rBNP) given at 600 pmol/min/kg for 2 min was approximately 38% lower than that of alpha-rANP. The effect of phosphoramidon on the clearance of rBNP was not significant and was similar to that of C-ANF(4-23). These results suggest that clearance receptor is involved in the clearance of the physiological levels of alpha-rANP and that NEP plays a major role in the clearance of a pharmacological dose of alpha-rANP, at which clearance receptors are thought to be saturated, and also indicate a pharmacokinetic difference between alpha-rANP and rBNP.

Endocrine-paracrine interaction in communication between the immune and endocrine systems. Activation of the hypothalamic-pituitary-adrenal axis in inflammation

There are bidirectional communications between the immune and endocrine systems. Cytokines produced in inflammatory foci cause changes in the endocrine system, including activation of the hypothalamic-pituitary-adrenal (HPA) axis. Hormones produced in the endocrine system, especially glucocorticoids, affect the immune system to modulate its function. This is an important endocrine system for the defence mechanism. In addition, bacterial lipopolysaccharide produces cytokines in the brain and endocrine organs which are considered to act through the paracrine mechanism to regulate the HPA axis. Endocrine-paracrine interaction is important for the defence mechanism of the organism.

Bacterial lipopolysaccharide-induced expression of interleukin-6 messenger ribonucleic acid in the rat hypothalamus, pituitary, adrenal gland, and spleen

Whereas the stimulatory effect of interleukin-6 (IL-6) on the hypothalamic-pituitary-adrenal (HPA) axis is well established, its mode of action in this axis has yet to be fully elucidated. To further study the role of IL-6 in the HPA axis, we compared the expression of IL-6 messenger RNA (mRNA) in the rat hypothalamus, pituitary, and adrenal gland with that in the spleen after ip or intracerebroventricular (icv) administration of bacterial lipopolysaccharide (LPS). After either ip or icv administration, LPS induced the expression of IL-6 mRNA, which consists of 1.2 kilobases (kb) and 2.4 kb subclasses, in all these tissues of the HPA axis as well as in the spleen. Although we used 100 times less amount of LPS for the icv administration than that used for ip LPS, plasma ACTH levels in both the conditions rapidly reached comparable levels. This icv dose induced IL-6 mRNA expression in the hypothalamus faster than ip dose but also stimulated IL-6 mRNA expression in the hypothalamus, pituitary, and adrenal gland more effectively and smoothly than the ip LPS dose did. Northern blot analysis revealed that in the hypothalamus, pituitary, and adrenals, the predominant subclass of IL-6 mRNA was not 1.2 kb but 2.4 kb. In contrast, this subclass was the minor component in the spleen induced under the same circumstances. These findings indicate that IL-6-synthesizing cells in the HPA axis differ in character from those in the spleen, and that LPS applied in vivo may modulate IL-6 expression in these cells directly and/or indirectly through secondarily activated functions in the neuronal or endocrine systems.

Possible compensatory role of parathyroid hormone-related peptide on maintenance of calcium homeostasis in patients with non-insulin-dependent diabetes mellitus

Recent studies have revealed that altered mineral and vitamin D metabolism is observed in diabetic patients with the complication of osteopenia. In order to elucidate the role of parathyroid hormone-related peptide (PTHrP) on calcium homeostasis in diabetes, we have measured the serum level and urinary excretion of PTHrP as well as other serum calcium-regulating hormones in 106 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 43 control subjects. The serum concentration of intact PTH was 2.34 +/- 0.13 (mean +/- SEM) pmol/l in NIDDM patients, which is significantly lower than the value of 3.11 +/- 0.14 pmol/l in the controls (p < 0.01). Both serum calcium and calcitonin, however, were not statistically different from controls. On the other hand, circulating PTHrP in NIDDM was 40.1 +/- 1.4 pmol/l, which is significantly elevated when compared to 27.3 +/- 1.3 pmol/l in the controls (p < 0.01). Moreover, urinary excretion of PTHrP also was significantly higher in NIDDM (p < 0.01). In the present study, the circulating calcium level was well preserved in NIDDM patients, although the PTH levels were shown to be decreased. The elevated serum PTHrP might, therefore, have a physiologically compensatory role on the calcium regulatory systems in NIDDM. Furthermore, this elevation is most likely due to the excess production of this peptide and not to the decrease in urinary excretion.

A nonsense mutation (TGG [Trp116]-->TAG [Stop]) in CYP11B1 causes steroid 11 beta-hydroxylase deficiency

Steroid 11 beta-hydroxylase deficiency (11 beta OHD), an autosomal recessive hereditary disease, accounts for 5-8% of cases of congenital adrenal hyperplasia. In this study, we carried out a molecular genetic analysis of CYP11B1 encoding steroid 11 beta-hydroxylase (P450c11) from a Japanese patient affected with this disease. Nucleotide sequence analysis of polymerase chain reaction-amplified products of the patient's genome revealed the occurrence of a stop codon in exon 2 due to a point mutation, TGG-->TAG (Trp116-->Stop). To further analyze the role of CYP11B2 encoding steroid 18-hydroxylase (P450c18) in the 11 beta OHD patient, CYP11B2 of the patient was also amplified and sequenced. In contrast to CYP11B1, there was no mutation in CYP11B2. Restriction fragment length polymorphism analysis indicated that the 11 beta OHD patient is homozygous and his unaffected parents are heterozygous for the mutation. When a cDNA corresponding to CYP11B1 of the 11 beta OHD patient was transfected into COS-7 cells, steroid 11 beta-hydroxylase activity was not detectable in mitochondria of the cells. These results demonstrate that intact P450c11 was not produced at all due to the nonsense mutation in CYP11B1 of the patient without any mutation in CYP11B2.

Selective impairment of the cytoplasmic Ca2+ response to glucose in pancreatic beta cells of streptozocin-induced non-insulin-dependent diabetic rats

Pancreatic islets from the streptozocin-induced non-insulin-dependent diabetes mellitus (NIDDM) rat model showed a diminished insulin response to 16.7 mmol/L glucose, but the insulin response to arginine remained intact. To evaluate the importance of intracellular calcium concentration ([Ca2+]i) in the diminished insulin response to glucose, the [Ca2+]i of pancreatic beta cells was investigated using fura-2. Glucose produced heterogeneous responses of [Ca2+]i, which were in beta-cell clusters of both the control and NIDDM groups. Many cells showed initial slight decreases of [Ca2+]i, which were followed by gradual and large increments of [Ca2+]i after glucose stimulation of beta cells in the control group. On the other hand, the increase of [Ca2+]i in response to glucose was markedly diminished in beta cells of the NIDDM group compared with controls. The average lag time to [Ca2+]i elevation of beta cells in the NIDDM group was significantly longer than that of the control group. Arginine produced marked increases of [Ca2+]i, in contrast to the effect of glucose stimulation in the NIDDM group. These results suggest that the diminished and delayed [Ca2+]i increases in beta cells of NIDDM rats in response to glucose stimulation are responsible for the selectively impaired insulin response to glucose in the rat model of NIDDM.

Anti-phosphoserine and anti-phosphothreonine antibodies modulate autophosphorylation of the insulin receptor but not EGF receptor

We examined the effect of anti-phosphothreonine and anti-phosphoserine antibodies on insulin receptor autophosphorylation. These antibodies did not affect insulin binding activity of the receptor. These antibodies, however, inhibited insulin-stimulated autophosphorylation of insulin receptor, while did not affect EGF-stimulated autophosphorylation of EGF receptor. The inhibition was reversed by adding large amounts of phosphoserine or phosphothreonine. These data suggest that phosphoserine and phosphothreonine on insulin receptor play an important role in insulin-induced conformational change of the receptor.

Evaluation of hypothalamo-pituitary-adrenocortical function in children by human corticotropin-releasing hormone (MCI-028) test

A dose of 1.5 micrograms/kg of MCI-028, human corticotropin-releasing hormone (hCRH), was administered intravenously to 38 children with non-endocrine short stature with normal function in the hypothalamo-pituitary-adrenocortical axis and to 71 children with a disorder in the same axis. Blood levels of adrenocorticotropic hormone (ACTH) and cortisol were determined to evaluate the axis. The 95% confidence limits of peak responses of ACTH and cortisol in non-endocrine short stature were between 17.2 and 135.3 pg/ml, and between 13.1 and 35.6 micrograms/dl, respectively, and were used as standards for children. When compared with these standards, the hormonal responses in children with various disorders in the hypothalamo-pituitary-adrenocortical axis were as follows: in two children with Cushing's syndrome caused by adrenal tumor, ACTH values were decreased and were not responsive to hCRH, while cortisol values, though within the normal limit, were not responsive; in children with primary adrenal insufficiency or congenital adrenal hyperplasia, cortisol values were decreased and not responsive, whereas ACTH values tended to be increased and ACTH response high except for 21 alpha-hydroxylase deficiency of congenital adrenal hyperplasia. In two cases of pituitary dwarfism complicated with ACTH deficiency, both ACTH and cortisol values were decreased and poorly responsive; and in children who were receiving glucocorticoid, both ACTH and cortisol values tended to be decreased and to respond poorly to hCRH. As for side effects, hot flushing was observed among 8.0% of the subjects after administration of hCRH. But this symptom was not severe and no other side effects of clinical importance were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Human corticotropin-releasing hormone test in patients with hypothalamo-pituitary-adrenocortical disorders

To assess the diagnostic usefulness of a synthetic human corticotropin-releasing hormone (CRH) formulation (Code No. MCI-028), we administered 100 micrograms of the peptide intravenously to 183 patients with hypothalamo-pituitary-adrenocortical (HPA) disorders, and obtained the following findings. Among the 183 patients, data from 125 patients were suitable for analyzing the effects of the test. In patients with Cushing's disease, high plasma adrenocorticotropic hormone (ACTH) and cortisol levels increased further in response to MCI-028, while in patients with adrenal Cushing's syndrome, low ACTH and high cortisol values remained unchanged. In patients with pituitary-type hypopituitarism or isolated ACTH deficiency, low ACTH and cortisol levels responded poorly or insignificantly to MCI-028, whereas those with hypothalamic hypopituitarism showed delayed and considerable degree of responses of plasma ACTH and little increase in plasma cortisol levels. In Addison's disease, high plasma ACTH increased further in response to MCI-028, but low cortisol levels did not change. In patients with Cushing's syndrome soon after successful surgical treatment, plasma ACTH responsiveness was low or different depending on the clinical course of the patient. Patients treated with high doses of glucocorticoids for non-endocrine diseases tended to show impaired ACTH and cortisol responsiveness to MCI-028. Side effects, including the transient flushing which was observed most frequently in this study, did not cause any clinical problems.

Downregulation of C-receptor by natriuretic peptides via ANP-B receptor in vascular smooth muscle cells

The natriuretic peptide system comprises at least three ligands, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) and three receptors, the ANP-A receptor, the ANP-B receptor, and the clearance (C) receptor. In the present study, the regulation of natriuretic peptide receptors by their ligands was investigated in cultured rat vascular smooth muscle cells (SMC). The treatment of vascular SMC with ANP, BNP, or CNP decreased the C-receptor density significantly, and the rank order of potency for this downregulation was CNP > ANP > BNP. This rank order was the same as that for guanosine 3',5'-cyclic monophosphate (cGMP) production by ANP, BNP, or CNP in vascular SMC and also the same as that for the ligand selectivity of the ANP-B receptor rather than the C-receptor. The incubation of vascular SMC with 8-bromoguanosine 3',5'-cyclic monophosphate significantly decreased the C-receptor density and its mRNA expression. These results suggest that the down-regulation of the C-receptor by natriuretic peptides is induced not by the binding of natriuretic peptides to the C-receptor but by the activation of the ANP-B receptor-cGMP pathway.

Human corticotropin-releasing hormone (hCRH) test: sex and age differences in plasma ACTH and cortisol responses and their reproducibility in healthy adults

The effectiveness and safety of MCI-028, a synthetic human corticotropin-releasing hormone (hCRH), as a diagnostic drug were examined in 65 healthy male and 24 healthy female adult volunteers. Mean maximum concentrations of plasma ACTH and cortisol after intravenous administration of 100 micrograms of MCI-028 were 3.0 and 2.0 times their basal concentrations, respectively, and there were no significant age or sex differences in the responses. Good reproducibility was observed in the responses in 59 male subjects who received a second administration after 1 to 2 weeks. Although slight adverse reactions such as mild and transient hot flushing were observed, these were not serious.

Cloning, functional expression and pharmacological characterization of a fourth (hSSTR4) and a fifth (hSSTR5) human somatostatin receptor subtype

Somatostatin exerts diverse effects in various tissues upon binding its specific membrane receptors. Recently, we have cloned three different somatostatin receptor subtypes. Here we report the sequence and functional expression of a fourth and a fifth human somatostatin receptor subtype, termed hSSTR4 and hSSTR5, respectively. The hSSTR4 encodes a protein of 388 amino acids and the hSSTR5 is a protein of 364 amino acids. There is 42-60% identity among the amino acid sequences of the five human somatostatin receptor subtypes identified to date. RNA blotting studies reveal that the hSSTR4 is expressed as a single transcript of 4.8 kb in MIA PaCa-2 cells, a cell line derived from human pancreatic cancer while the hSSTR5 is undetectable in the tissues examined. The hSSTR4 and hSSTR5 transiently expressed in COS1 cells exhibit specific binding to somatostatin-14 with IC50 values of 1.6 and 0.16 nM, respectively. We also have characterized the binding affinity of various somatostatin analogues to the hSSTR4 and hSSTR5. The rank of the potency of the analogues are: somatostatin-14 = somatostatin-28 >> RC-160 >> SMS201-995 for the hSSTR4 and somatostatin-28 > somatostatin-14 >> RC-160 > SMS201-995 for the hSSTR5. These results suggest that diverse actions of somatostatin are mediated by at least five somatostatin receptor subtypes with potentially different function.

Immunoreactive corticotropin-releasing hormone levels in discrete hypothalamic nuclei of genetically obese Zucker rats

The levels of immunoreactive corticotropin-releasing hormone (ir-CRH) were measured in discrete hypothalamic nuclei and the median eminence of obese Zucker rats and their lean littermates. More than 90% of total hypothalamic ir-CRH was detected in the median eminence in both obese and lean rats. Though ir-CRH levels in the paraventricular nucleus of obese rats tended to be lower than those of their lean littermates, no significant difference of ir-CRH levels was observed in any hypothalamic nuclei studied between obese and lean rats. However, ir-CRH levels in the median eminence of obese rats were significantly lower than those of their lean littermates (5263 +/- 438 pg/tissue vs. 7050 +/- 473 pg/tissue, P < 0.05). These results suggest that the hypoactive hypothalamic CRH tonus would play some role in the phenotypic expression of obesity in the genetically obese Zucker rats.

Lymphocytic infundibuloneurohypophysitis as a cause of central diabetes insipidus

BACKGROUND

Central diabetes insipidus may be familial, secondary to hypothalamic or pituitary disorders, or idiopathic. Idiopathic central diabetes insipidus is characterized by selective hypofunction of the hypothalamic-neurohypophysial system, but its cause is unknown.

METHODS

We studied 17 patients with idiopathic diabetes insipidus, in whom the duration of the disorder ranged from 2 months to 20 years. Only four patients had been treated with vasopressin before the study began. All the patients underwent endocrinologic studies and magnetic resonance imaging (MRI) with a 1.5-T superconducting unit, and two patients had biopsies of the neurohypophysis or the pituitary stalk.

RESULTS

Nine of the 17 patients had thickening of the pituitary stalk, enlargement of the neurohypophysis, or both and lacked the hyperintense signal of the normal neurohypophysis. In the remaining eight patients, the pituitary stalk and the neurohypophysis were normal, although the hyperintense signal was absent. The abnormalities of thickening and enlargement were seen on MRI only in the patients who had had diabetes insipidus for less than two years, and the abnormalities disappeared during follow-up, suggesting a self-limited process. In addition to vasopressin deficiency, two patients had mild hyperprolactinemia and nine had impaired secretory responses of growth hormone to insulin-induced hypoglycemia. The two biopsies revealed chronic inflammation, with infiltration of lymphocytes (mainly T lymphocytes) and plasma cells.

CONCLUSIONS

Diabetes insipidus can be caused by lymphocytic infundibuloneurohypophysitis, which can be detected by MRI. The natural course of the disorder is self-limited.

Insulin sensitivity, insulin secretion, and glucose effectiveness in anorexia nervosa: a minimal model analysis

The aim of the present study was to estimate insulin secretion, insulin sensitivity (SI), and glucose effectiveness (SG) in subjects with anorexia nervosa. Eight nondiabetic anorectic patients who were dietary restricters and 16 age- and sex-matched healthy control subjects without family history of diabetes were studied. They underwent a modified frequently sampled intravenous glucose tolerance test; glucose (300 mg/kg body weight) was administered and insulin (4 mU/kg body weight/min) was infused from 20 to 25 minutes after administration of glucose. SI and SG were estimated by Bergman's minimal model method. Basal glucose (75.5 +/- 2.1 v 87.1 +/- 1.7 mg/dL) and insulin (3.6 +/- 0.4 v 6.3 +/- 0.5 microU/mL) concentrations were significantly lower in anorectic patients than in control subjects (P < .01). No significant difference was observed in glucose disappearance rate (KG) between the anorectic and control subjects (1.56 +/- 0.5 v 2.26 +/- 0.15%/min). Insulin secretion assessed by the integrated area of plasma insulin above basal level during the first 20 minutes after intravenous stimulation with glucose was significantly decreased in anorectic patients (283 +/- 69 microU.mL-1 x min) compared with control subjects (529 +/- 63 microU.mL-1 x min, P < .05). SI was significantly increased in anorectic patients compared with control subjects (11.2 +/- 1.2 v 7.5 +/- 1.0 x 10(-4) min-1 +/-.[microU/mL]-1, P < .05). However, SG was significantly decreased in anorectic patients (0.015 +/- 0.003 min-1) compared with control subjects (0.023 +/- 0.002 min-1, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and characterization of new anti-adrenocorticotropin rabbit neutrophil peptides (defensins)

Neutrophil peptides (NPs, defensins), which consist of approximately 30 amino acids with a highly conserved backbone of six Cys residues, possess several biological activities, such as antimicrobial, antiviral, cytotoxic, and anti-adrenocorticotropin (corticostatic) activity in vitro. In the rabbit, six NPs, i.e., NP-1, -2, -3A, -3B, -4, and -5, have been isolated, among them, NP-3A has the most potent corticostatic activity, which involves the inhibition of adrenocorticotropin-stimulated corticosterone synthesis in adrenal cells. Using a sensitive radioimmunoassay for NP-3A and reverse-phase HPLC, we found a novel component in rabbit tissue extracts with NP-3A-like immuno-reactivity. We further purified and characterized the component and found two novel peptides. One of these peptides, designated NP-6, has an amino acid sequence identical to that of NP-3A except for three amino acids, i.e. Leu11, Phe13, and Gln15, in the central portion of the sequence. The other has a sequence corresponding to that of NP-6 except that the N-terminal Gly was deleted and is thus named des-G1-NP-6. Using chemically synthesized NP-6 and des-G1-NP-6, we measured their putative corticostatic activities by a dispersed rat adrenal cell bioassay. NP-6 showed corticostatic activity comparable to that of NP-3A while des-G1-NP-6 showed weak activity. These findings are also compatible with the notion that the N-terminal Gly, but not the central portion, is important for the anti-adrenocorticotropin activity of the NPs.

Intravenous glucose tolerance test-derived glucose effectiveness in physically trained humans

Glucose effectiveness (SG) and insulin sensitivity of sedentary and physically trained males were estimated by the minimal model approach. Trained subjects, who ran 86 +/- 10 km/wk and had 37% higher maximal oxygen consumption than that of sedentary subjects (56.2 +/- 1.2 vs. 40.9 +/- 1.4 ml.kg-1 x min-1, P < 0.01), were studied 16 h and 1 wk after their last training session. After overnight fasting, glucose was administered intravenously (300 mg/kg body wt) within 2 min, and insulin was infused (approximately 13-20 mU/kg given over 5 min) from 20 to 25 min after administration of glucose. Glucose disappearance constant values as an estimate of glucose tolerance were significantly higher in trained subjects after 16 h and 1 wk of their training session (3.29 +/- 0.48 and 3.60 +/- 0.64%/min) than in sedentary subjects (1.92 +/- 0.30%/min, P < 0.05). Insulin sensitivity in trained subjects measured after 16 h and 1 wk of their last training session (26.2 +/- 4.4 and 24.3 +/- 6.0 x 10(-5) min-1 x pM-1) was also higher than that of sedentary subjects (10.3 +/- 1.2 x 10(-5) min-1 x pM-1, P < 0.05). SG, the ability of glucose itself to increase peripheral glucose uptake and suppress hepatic glucose output, was significantly higher in trained subjects after 16 h and 1 wk of their last training session (0.028 +/- 0.003 and 0.030 +/- 0.004/min) than in sedentary subjects (0.017 +/- 0.002/min, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular expression of brain natriuretic peptide in hypertrophic cardiomyopathy

BACKGROUND

Brain natriuretic peptide (BNP), as a cardiac hormone, is expressed together with atrial natriuretic peptide (ANP) in the ventricles in congestive heart failure. However, the ventricular expression of BNP in hypertrophic cardiomyopathy (HCM) with normal systolic function is still unclear.

METHODS AND RESULTS

The study population consisted of 39 HCM patients with asymmetric septal hypertrophy and 10 control subjects without any specific cardiac disease. Eleven cases of HCM were obstructive (HOCM), and the other 28 cases were nonobstructive (HNCM). All of these patients had a normal ejection fraction. Immunohistochemical analysis of endomyocardial biopsy specimens with specific monoclonal antibodies showed BNP immunoreactivity in the HOCM group (5/10, 50%) but not in the HNCM group (0/22) or in control subjects (0/5). In HOCM, left ventricular end-diastolic pressure was significantly higher in the BNP-positive patients than the BNP-negative patients. Histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis were greater in BNP-positive patients than BNP-negative patients in HCM. However, the expression had no significant relation with other clinical parameters. The elevation of the BNP plasma level versus control subjects was marked in both HOCM (85-fold) and HNCM (23-fold). By contrast, the elevation of the ANP plasma level versus control subjects was mild in HOCM (5.7-fold) and HNCM (4.2-fold). The ratio of BNP level to ANP level was higher in HOCM (4.16) than in HNCM (1.46) and control subjects (0.28), and it was higher than the ratio previously reported for severe congestive heart failure (1.72).

CONCLUSIONS

These findings suggest that BNP is expressed in the ventricular myocytes of HCM with normal systolic function. In HOCM, ventricular expression of BNP may be augmented in response to both obstruction and diastolic dysfunction.

Plasma brain natriuretic peptide level in pregnant women with pregnancy-induced hypertension

OBJECTIVE

To investigate the involvement of brain natriuretic peptide in the circulation of pregnant women with pregnancy-induced hypertension.

METHODS

We determined the plasma levels of brain and atrial natriuretic peptides in a cross-sectional study of 36 normal pregnant women and 17 women with pregnancy-induced hypertension.

RESULTS

During normal pregnancy, the plasma brain natriuretic peptide level was similar to that in nonpregnant women, but the plasma atrial natriuretic peptide level in the second trimester was significantly higher than that in nonpregnant women (P < .05). In women with severe pregnancy-induced hypertension, the plasma brain natriuretic peptide level was eight times higher than that in normal pregnant women in the third trimester; the plasma atrial natriuretic peptide level in the same patients was three times higher than that in normal pregnancy. The plasma brain natriuretic peptide level showed a positive correlation with the mean blood pressure (r = 0.62, P < .001).

CONCLUSION

The present findings suggest that brain natriuretic peptide is increased in the plasma of women with pregnancy-induced hypertension and that brain natriuretic peptide, in concert with atrial natriuretic peptide, participates in maintaining homeostasis of the maternal circulation.