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Hashimoto Y, Nakao K, Hama N, Imura H, Mori S, Yamaguchi M, Yasuhara M, Hori R. Clearance mechanisms of atrial and brain natriuretic peptides in rats. Pharm Res 1994; 11:60-4. [PMID: 8140057 DOI: 10.1023/a:1018941626731] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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Imura H, Fukata J. Endocrine-paracrine interaction in communication between the immune and endocrine systems. Activation of the hypothalamic-pituitary-adrenal axis in inflammation. Eur J Endocrinol 1994; 130:32-7. [PMID: 8124477 DOI: 10.1530/eje.0.1300032] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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.
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78
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Muramami N, Fukata J, Tsukada T, Kobayashi H, Ebisui O, Segawa H, Muro S, Imura H, Nakao K. Bacterial lipopolysaccharide-induced expression of interleukin-6 messenger ribonucleic acid in the rat hypothalamus, pituitary, adrenal gland, and spleen. Endocrinology 1993; 133:2574-8. [PMID: 8243280 DOI: 10.1210/endo.133.6.8243280] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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79
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Ishida H, Suzuki K, Someya Y, Nishimura M, Sugimoto C, Goto M, Taguchi Y, Kasahara H, Kadowaki S, Imura H. Possible compensatory role of parathyroid hormone-related peptide on maintenance of calcium homeostasis in patients with non-insulin-dependent diabetes mellitus. ACTA ENDOCRINOLOGICA 1993; 129:519-24. [PMID: 8109185 DOI: 10.1530/acta.0.1290519] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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.
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Naiki Y, Kawamoto T, Mitsuuchi Y, Miyahara K, Toda K, Orii T, Imura H, Shizuta Y. A nonsense mutation (TGG [Trp116]-->TAG [Stop]) in CYP11B1 causes steroid 11 beta-hydroxylase deficiency. J Clin Endocrinol Metab 1993; 77:1677-82. [PMID: 7903314 DOI: 10.1210/jcem.77.6.7903314] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
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.
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81
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Tsuji K, Taminato T, Ishida H, Okamoto Y, Tsuura Y, Kato S, Kurose T, Okada Y, Imura H, Seino Y. Selective impairment of the cytoplasmic Ca2+ response to glucose in pancreatic beta cells of streptozocin-induced non-insulin-dependent diabetic rats. Metabolism 1993; 42:1424-8. [PMID: 8231837 DOI: 10.1016/0026-0495(93)90193-r] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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Kono S, Kuzuya H, Yamada K, Yoshimasa Y, Okamoto M, Inoue G, Hayashi T, Nakao K, Imura H. Anti-phosphoserine and anti-phosphothreonine antibodies modulate autophosphorylation of the insulin receptor but not EGF receptor. Biochem Biophys Res Commun 1993; 196:216-22. [PMID: 8216295 DOI: 10.1006/bbrc.1993.2237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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83
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Tanaka T, Hibi I, Shimizu N, Imura H, Tanaka K, Fukata J, Fujieda K, Ichimura T, Kuribayashi T, Ito K. Evaluation of hypothalamo-pituitary-adrenocortical function in children by human corticotropin-releasing hormone (MCI-028) test. Endocr J 1993; 40:581-9. [PMID: 7951524 DOI: 10.1507/endocrj.40.581] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
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)
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84
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Fukata J, Shimizu N, Imura H, Hibi I, Tanaka K, Tanaka T, Nakagawa S, Takebe K, Kimura K, Yoshinaga K. Human corticotropin-releasing hormone test in patients with hypothalamo-pituitary-adrenocortical disorders. Endocr J 1993; 40:597-606. [PMID: 7951526 DOI: 10.1507/endocrj.40.597] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
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.
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85
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Kishimoto I, Nakao K, Suga S, Hosoda K, Yoshimasa T, Itoh H, Imura H. Downregulation of C-receptor by natriuretic peptides via ANP-B receptor in vascular smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 265:H1373-9. [PMID: 8238425 DOI: 10.1152/ajpheart.1993.265.4.h1373] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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MESH Headings
- Animals
- Blotting, Northern
- Cells, Cultured
- Cyclic GMP/analogs & derivatives
- Cyclic GMP/biosynthesis
- Cyclic GMP/pharmacology
- Down-Regulation
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Natriuretic Agents/pharmacology
- RNA, Messenger/metabolism
- Radioligand Assay
- Receptors, Atrial Natriuretic Factor/classification
- Receptors, Atrial Natriuretic Factor/drug effects
- Receptors, Atrial Natriuretic Factor/metabolism
- Recombinant Proteins
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86
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Tanaka K, Shimizu N, Imura H, Fukata J, Hibi I, Tanaka T, Nakagawa S, Fujieda K, Takebe K, Yoshinaga K. Human corticotropin-releasing hormone (hCRH) test: sex and age differences in plasma ACTH and cortisol responses and their reproducibility in healthy adults. Endocr J 1993; 40:571-9. [PMID: 7951523 DOI: 10.1507/endocrj.40.571] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
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.
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87
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Yamada Y, Kagimoto S, Kubota A, Yasuda K, Masuda K, Someya Y, Ihara Y, Li Q, Imura H, Seino S. Cloning, functional expression and pharmacological characterization of a fourth (hSSTR4) and a fifth (hSSTR5) human somatostatin receptor subtype. Biochem Biophys Res Commun 1993; 195:844-52. [PMID: 8373420 DOI: 10.1006/bbrc.1993.2122] [Citation(s) in RCA: 196] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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.
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88
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Nakaishi S, Nakai Y, Fukata J, Naito Y, Usui T, Fukushima M, Jingami H, Nakao K, Imura H. Immunoreactive corticotropin-releasing hormone levels in discrete hypothalamic nuclei of genetically obese Zucker rats. Neurosci Lett 1993; 159:29-31. [PMID: 8264973 DOI: 10.1016/0304-3940(93)90790-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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.
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89
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Imura H, Nakao K, Shimatsu A, Ogawa Y, Sando T, Fujisawa I, Yamabe H. Lymphocytic infundibuloneurohypophysitis as a cause of central diabetes insipidus. N Engl J Med 1993; 329:683-9. [PMID: 8345854 DOI: 10.1056/nejm199309023291002] [Citation(s) in RCA: 217] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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.
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90
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Fukushima M, Nakai Y, Taniguchi A, Imura H, Nagata I, Tokuyama K. Insulin sensitivity, insulin secretion, and glucose effectiveness in anorexia nervosa: a minimal model analysis. Metabolism 1993; 42:1164-8. [PMID: 8412770 DOI: 10.1016/0026-0495(93)90275-s] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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)
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91
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Fuse N, Hayashi Y, Fukata J, Tominaga T, Ebisui O, Satoh Y, Isohara T, Uno I, Imura H. Purification and characterization of new anti-adrenocorticotropin rabbit neutrophil peptides (defensins). EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 216:653-9. [PMID: 8397087 DOI: 10.1111/j.1432-1033.1993.tb18185.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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.
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92
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Tokuyama K, Higaki Y, Fujitani J, Kiyonaga A, Tanaka H, Shindo M, Fukushima M, Nakai Y, Imura H, Nagata I. Intravenous glucose tolerance test-derived glucose effectiveness in physically trained humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 265:E298-303. [PMID: 8368300 DOI: 10.1152/ajpendo.1993.265.2.e298] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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)
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93
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Iwata Y, Imura H, Suzuki N. Determination of nanogram levels of lanthanoids in a marine macro-alga by neutron activation analysis combined with separation by selective precipitation. J Radioanal Nucl Chem 1993. [DOI: 10.1007/bf02041850] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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94
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Hasegawa K, Fujiwara H, Doyama K, Miyamae M, Fujiwara T, Suga S, Mukoyama M, Nakao K, Imura H, Sasayama S. Ventricular expression of brain natriuretic peptide in hypertrophic cardiomyopathy. Circulation 1993; 88:372-80. [PMID: 8339400 DOI: 10.1161/01.cir.88.2.372] [Citation(s) in RCA: 150] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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.
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95
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Shimatsu A, Ishikawa Y, Kasai K, Ihara C, Mizuta H, Mori K, Imura H. Role of substance P in regulating sympatho-adrenal function in conscious rats. REGULATORY PEPTIDES 1993; 46:260-2. [PMID: 7692510 DOI: 10.1016/0167-0115(93)90053-b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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96
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Itoh H, Sagawa N, Mori T, Mukoyama M, Nakao K, Imura H. Plasma brain natriuretic peptide level in pregnant women with pregnancy-induced hypertension. Obstet Gynecol 1993; 82:71-7. [PMID: 8515929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
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.
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97
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Shimatsu A, Tanoh T, Tsuji I, Yanaihara N, Imura H. Interaction between nicotinic cholinergic receptors and alpha-2 adrenergic systems in regulating growth hormone secretion in conscious rats. YAKUBUTSU, SEISHIN, KODO = JAPANESE JOURNAL OF PSYCHOPHARMACOLOGY 1993; 13:111-117. [PMID: 7694432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The possible role and mechanism of central nicotinic cholinergic receptors in regulating growth hormone (GH) secretion were investigated in conscious, unrestrained male rats. The administration of galanin (GAL), a neuropeptide, GH-releasing hormone (GHRH) and UK 14304, an alpha-2 adrenergic agonist, caused increases in plasma GH levels. Pretreatment of the animals with hexamethonium significantly reduced GAL- and GHRH-induced GH secretion, but UK 14304-induced GH release was not affected. Neosurugatoxin, a nicotinic cholinergic neurotoxin, partially inhibited GAL-induced GH release. Pretreatment with neostigmine elevated basal plasma GH levels and partially inhibited GAL-induced GH secretion. However, GHRH- and UK 14304-induced GH release was additive to the effect of neostigmine. Yohimbine inhibited GH release induced by UK 14304, GAL and GHRH. Neostigmine-induced GH secretion was partially inhibited by yohimbine and phenoxybenzamine. These findings suggest that central nicotinic receptors have a stimulatory role in regulating GH secretion and that the nicotinic cholinergic system coupled with the alpha-2 adrenergic mechanism is involved in GH secretion induced by galanin in conscious rats.
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98
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Hashimoto Y, Mori S, Hama N, Nakao K, Imura H, Yamaguchi M, Yasuhara M, Hori R. Nonlinear mixed effect modeling of the pharmacodynamics of natriuretic peptides in rats. JOURNAL OF PHARMACOKINETICS AND BIOPHARMACEUTICS 1993; 21:281-97. [PMID: 8258768 DOI: 10.1007/bf01059780] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Natriuretic peptides have not only natriuretic/diuretic but also hypotensive activities, and the decreased renal perfusion caused by the excessive hypotension is known to attenuate the diuretic actions. The present study was designed to examine the relationship between the dosing (intravenous constant infusion) rates and the diuretic actions of alpha-rat atrial natriuretic peptide (alpha-rANP) and rat brain natriuretic peptide (rBNP) in rats, and population (nonlinear mixed effect model) analysis was applied to these complicated diuretic actions. The intrinsic diuretic activities of alpha-rANP and rBNP could be analyzed, and the effects of blood pressure, heart rate, and also inhibition of degradation enzyme on the diuresis of natriuretic peptides were estimated simultaneously. The population analysis was useful for analyzing such pharmacodynamic data for which the individual analysis could not be applied easily.
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Sugawa H, Smith E, Imura H, Mori T. A thyroid cancer specific monoclonal antibody which recognizes cryptic epitope(s) of human thyroglobulin. Mol Cell Endocrinol 1993; 93:207-11. [PMID: 7688705 DOI: 10.1016/0303-7207(93)90125-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A monoclonal antibody (TCM-9) specific for human thyroid cancer but not for Graves' disease, adenoma or normal thyroid tissue was shown to recognize a 300 K protein but not to bind to native or mature human thyroglobulin (Tg). In this study, we investigated further the antigen recognized by TCM-9. When purified Tg was treated with periodate, dithiothreitol (DTT) and sodium dodecyl sulfate (SDS), immunoblotting of treated Tg with TCM-9 revealed an apparent enhancement of the staining only with DTT-treated Tg. Furthermore, the DTT-treated Tg was shown to bind dose-dependently to plates coated with TCM-9. We performed SDS-PAGE and immunoblot analyses on the immune complex obtained from a homogenate of thyroid cancer tissue which was preincubated with an excess of anti-Tg monoclonal antibody. When the protein was autoradiographed with [125I]TCM-9, a definite band was observed. The results indicate that TCM-9 is likely to be directed against a masked epitope of thyroglobulin which can be exposed after treatment with a reducing agent.
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100
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Akamizu T, Inoue D, Kosugi S, Ban T, Kohn LD, Imura H, Mori T. Chimeric studies of the extracellular domain of the rat thyrotropin (TSH) receptor: amino acids (268-304) in the TSH receptor are involved in ligand high affinity binding, but not in TSH receptor-specific signal transduction. Endocr J 1993; 40:363-72. [PMID: 7920890 DOI: 10.1507/endocrj.40.363] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A series of chimeric TSH-LH/CG receptors were constructed by substituting homologous segments of the extracellular domain of the rat TSH receptor with corresponding segments of rat LH/CG receptor: C1 (amino acids 37-123 substituted), C2 (91-112), C3 (173-234), C4 (233-266), C5 (268-304), C6 (112-305) and C7 (36-404). After transfection in Cos-7 cell, TSH- and LH/CG-receptor activities of these chimeras were evaluated and compared with those of deletion mutants involving the same residues [Kosugi et al. Thyroid 1:321 (1991)]. Western blot analyses revealed that most of the chimeric receptor proteins were normally synthesized and integrated in the membrane of transfected Cos-7 cells: an antibody to a TSH receptor specific synthetic peptide (residues 352-366) identified 170-190kDa and 90-100kDa TSH receptor structures in the plasma membrane fractions of Cos-7 cells transfected with wild-type TSH receptor cDNA and the C1 to C6 chimeras, but not C7 or wild LH/CG receptor cDNA. Despite this, no receptor except C5 exhibited any significant TSH receptor activities either in [12I]TSH binding or in cAMP responses to TSH and thyroid-stimulating antibodies (TSAbs) from Graves' patients. The chimeric receptor C5 exhibited only low affinity TSH binding (Kd = 3.5 x 10(-8) M), as did its counterpart the M2C mutant with residues 268-304 deleted. However, unlike M2C, C5 demonstrated a significant cAMP response to TSH as well as to TSAbs. The cAMP increase in response to TSH in the wild type receptor was observed at 10(-11) M TSH. In C5 the response was first evident at 10(-10) M TSH, but the maximum cAMP stimulation by TSH and TSAbs in C5 (EC50 = 6.7 x 10(-10) M) was approximately the same as the wild type receptor (EC50 = 1.5 x 10(-10) M). Inhibition of either TSH- or TSAb- stimulated cAMP increase by thyroid-stimulating blocking antibodies (TSBAbs) was also preserved in C5. These results suggest that amino acids 268-304 do not include an important determinant required for signal transduction, since a significant cAMP response to TSH and TSAbs was observed in the C5 receptor with these residues substituted. Additionally, these residues appear to be involved in ligand high affinity binding because high affinity TSH binding was lost in the chimeric receptor C5.
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