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T Yoshimi

Publications and source records attributed to T Yoshimi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Distribution and concentration of urocortin, and effect of adrenalectomy on its content in rat hypothalamus.

We developed a specific and sensitive radioimmunoassay (RIA) for rat urocortin (rUcn) and investigated the tissue distribution and concentration of immunoreactive (IR-)Ucn in rats. Antiserum was obtained by immunizing rabbits with synthetic rUcn21-35 coupled with bovine thyroglobulin. 125I-[Tyr]18-rUcn19-37 was used as the tracer. The RIA detected synthetic rUcn1-40 as low as 0.4 fmol/tube, and did not cross-react with other corticotropin-releasing factor-related peptides. IR-Ucn was widely distributed in central nervous system, endocrine organs, and digestive system. Its concentration was highest in pituitary (11.0 +/- 1.36 pmol/g.w.w., mean +/- SEM, n=4). Reverse-phase HPLC revealed that hypothalamic IR-Ucn had similar chromatographic mobility to synthetic rUcn1-40. However, bilateral adrenalectomy did not influence the hypothalamic IR-Ucn content. Our results suggest that Ucn may play important roles in various tissues in normal rats, but not behave as a hypothalamic hypophysiotropic factor in mediating adrenocorticotropin secretion in adrenalectomized rats.

Adrenal Glands↗
PubMed1998

Alterations in the enzyme activity and protein contents of protein disulfide isomerase in rat tissues during fasting and refeeding.

Protein disulfide isomerase (PDI) is an enzyme that participates in the formation of disulfide bonds. It is also known to be the subunits of some enzymes and the membrane-associated thyroid hormone-binding protein. In this study, we measured the quantitative distribution of PDI protein in rat tissues and examined the relationship between protein level and enzyme activity in PDI during fasting and refeeding. Western blotting with specific anti-PDI antiserum detected the PDI protein band of 55 kd. Among several tissues, liver contained the largest amount of PDI protein, followed by kidney and fat, in which one-third to one-fourth of the hepatic PDI protein existed. The PDI protein band was also detected in heart and muscle. Fasting for 3 days decreased PDI protein levels in rat liver by 40%; control levels were recovered after 3 days of refeeding. The same change was observed in kidney. PDI activity, measured by the scrambled ribonuclease method, did not show the parallel alteration to PDI protein level in liver and kidney. Isomerase activity decreased to 50% of control values during fasting, but did not recover by refeeding. Thyroidal status did not affect either PDI protein level or isomerase activity. These findings show that fasting and refeeding affect PDI protein and enzyme activity, and that PDI protein level does not always reflect PDI activity.

Animals↗
PubMed1998

Effect of urocortin and its interaction with adrenocorticotropin (ACTH) secretagogues on ACTH release.

We examined the effect of urocortin (Ucn) on the adrenocorticotropin (ACTH) release from cultured rat anterior pituitary cells and AtT 20 cells. Synthetic rat (r)Ucn was not soluble in 0.1 N HCl but soluble in alkaline solvents with diminished corticotropin-releasing activity. rUcn dissolved in 0.1 M sodium phosphate buffer as a stock solution maintained its bioactivity and had the equal corticotropin-releasing activity with rat/human corticotropin-releasing factor (r/hCRF). rUcn stimulated the adrenocorticotropin release via CRF-receptors accompanied by the additive effect with r/hCRF, the synergistic effect with arginine vasopressin and the dose-dependent inhibition of a potent CRF-receptor antagonist.

Adrenocorticotropic Hormone↗
PubMed1998

Identification of bile canalicular cell surface antigen HAM.4 as dipeptidyl peptidase IV (DPPIV) and characterization of its role in hepatic regeneration after partial hepatectomy in rats.

Dipeptidyl peptidase IV (DPPIV) has been implicated in the control of cell growth and differentiation. A rat hepatocyte membrane antigen recognized by a monoclonal antibody (HAM.4) has now been shown to be identical to DPPIV by immunoblot analysis and amino acid sequencing. The amounts of DPPIV immunoreactive protein and enzymatic activity in serum increased in a manner independent of de novo protein synthesis, and without any biochemical or immunohistochemical changes in hepatic DPPIV, during liver regeneration after partial hepatectomy in rats. DPPIV purified from serum by HAM.4 antibody-based affinity chromatography lacked the NH2-terminal 36 amino acids of the membrane-bound enzyme, suggesting that proteolytic cleavage may mediate the release of DPPIV into serum. No significant differences in the restoration of liver mass or in hepatic DNA synthesis were apparent between DPPIV-deficient and normal rats after partial hepatectomy, suggesting that DPPIV may not be essential for hepatic regeneration.

Amino Acids↗
PubMed1998

Stimulatory effect of calcitonin gene-related peptide on adrenocorticotropin release from rat anterior pituitary cells.

In the present study, we examined the direct regulatory effect of rat calcitonin gene-related peptide (CGRP) on adrenocorticotropin (ACTH) release from rat cultured anterior pituitary cells. CGRP significantly increased ACTH release at concentrations of 10(-8)-10(-11) M. The ACTH release was gradually increased by CGRP concentrations lower than 10(-10) M, and was decreased at concentrations higher than 10(-9) M, presenting a bell-shaped dose-response curve. As well as having an additive effect on corticotropin-releasing factor-induced ACTH release, CGRP stimulated the accumulation of intracellular cAMP. The CGRP-induced ACTH release was inhibited by a protein kinase A inhibitor, suggesting that its stimulatory effect on the ACTH release was mediated via an adenylate-cyclase-protein kinase system. CGRP-like immunoreactive nerve fibers have been reported to innervate the anterior pituitary, so that the stimulatory effect of CGRP on the ACTH release suggests that this peptide may be involved in neural regulation of hormone secretion in the anterior pituitary.

Adrenocorticotropic Hormone↗
PubMed1997

Increases in the mRNA levels of gamma-glutamyltransferase and heme oxygenase-1 in the rat lung after ozone exposure.

gamma-Glutamyltransferase (GGT) and heme oxygenase-1 (HO-1) are induced by chemical and physical stresses producing an oxidative burden on tissues and cells. Both enzymes are proposed to have an antioxidant role in protecting cells and tissues from oxidative burden. To explore the effects of ozone (O3), the major oxidant in photochemical smog, on the expression of GGT and HO-1 genes in the lung, we exposed rats to 0.4 ppm O3 for up to 7 days. After exposures, mRNA levels of GGT and HO-1 in the lung were measured by RNA blot analysis. Although a 1-day exposure did not change either GGT or HO-1 mRNA levels in the lung, both genes responded to prolonged exposure to O3. GGT mRNA was increased to 149% (P < 0.01) and 158% (P < 0.01) of the control by 3- and 7-day exposures, respectively. HO-1 mRNA was also elevated to 174% (P < 0.01) and 184% (P < 0.001) of the control after 3- and 7-day exposures, respectively. The elevation of GGT and HO-1 mRNA after prolonged exposure to O3 suggests that expression of these genes is not involved in the acute respiratory response, but in the recovery process from lung damage induced by O3.

Animals↗
PubMed1997

Structural organization of the human prostaglandin EP3 receptor subtype gene (PTGER3).

Prostaglandin EP3 receptor subtype is a seven-membrane-spanning protein with multiple C-terminal tails generated by alternative mRNA splicing. We report here the structural organization of the human EP3 gene (PTGER3). The human EP3 gene spanned more than 80 kb and was composed of 10 exons separated by nine introns. Exon 1 and the 5' 180-bp portion of exon 2 (exon 2a) encoded the seven transmembrane domains and 10 amino acid residues of the cytoplasmic tail, which are common to all EP3 isoforms. The 3' 3461-bp portion of exon 2 (exon 2b) or combinations of exons 3-10 encoded the EP3 isoform-specific C termini and formed their 3'-untranslated regions by multiple fashions of alternative mRNA splicing. Exons 2b, 4, 6, and 10 contained polyadenylation sites. The EP3 gene formed nine distinct mRNAs encoding eight EP3 isoforms, two of which were novel ones tentatively designated EP3-V and EP3-VI. The transcription initiation sites of the human EP3 gene were mapped 227 to approximately 231 bp upstream of the ATG start codon. The 360-bp 5'-flanking region contained a TATA box-like sequence, a GC box, and several cis-acting regulatory elements. The present study provides insight into the molecular mechanisms underlying the prostanoid receptor family.

Alternative Splicing↗
PubMed1997

High incidence of positive autoantibodies against thyroid peroxidase and thyroglobulin in patients with sarcoidosis.

OBJECTIVE: Although abnormalities of the humoral immune system, such as increased immunoglobulin production, are known in sarcoidosis, the relationship between sarcoidosis and autoimmune disorders in uncertain. We studied the incidence of thyroid autoantibodies and the prevalence of Hashimoto's thyroiditis in patients with sarcoidosis. PATIENTS AND MEASUREMENTS: Sixty-two patients with pulmonary sarcoidosis, diagnosed by a combination of clinical, radiographic and histological findings were studied. As controls, three groups of subjects aged 40 and over without a known history of thyroid disease (60 patients with pulmonary diseases other than sarcoidosis, 88 hospital employees and 82 company workers), were also analysed. Antibodies against thyroid peroxidase (TPO-Ab) and purified thyroglobulin (Tg-Ab) were measured by radioimmunoassay and antibodies against microsomal antigen (MCHA) and thyroglobulin (TGHA), by haemagglutination. RESULTS: Seventeen of 62 patients (27.4%) had either positive TPO-Ab or Tg-Ab or both. All the patients with positive thyroid autoantibodies were of middle or advanced age, and the incidence of positive TPO-Ab/Tg-Ab in patients with sarcoidosis aged 40 and over was 54.5% in males, 32.4% in females and 37.8% overall. The prevalence was significantly higher in males compared to age-matched control males (0-7.7% in the controls), and in female patients was twice that found in controls (11.8-16.3%). Seven patients had Hashimoto's thyroiditis, indicating that the prevalence was 11-3%, and much higher than that previously reported. CONCLUSIONS: The data show a remarkably high incidence of thyroid autoantibodies in patients of middle of advanced age with sarcoidosis, especially in males, and a higher prevalence of Hashimoto's thyroiditis than in previous reports.

Age Factors↗
PubMed1997

Adrenal adenoma with bilateral adrenocortical nodular change in a patient with Cushing's syndrome.

We report a 57-year-old male patient with adrenocorticotrophin (ACTH)-independent Cushing's syndrome and long-standing hypertension. Both abdominal computed tomographic scan and magnetic resonance imaging revealed bilateral adrenal enlargement with the presence of a tumour in the left adrenal. Marked uptake of 131I-6 beta-iodomethyl-19-norcholesterol was observed only in the left adrenal gland. Left adrenalectomy and biopsy of the right adrenal gland were subsequently performed. Histological examination revealed the presence of an adrenocortical adenoma in the left adrenal with multiple adrenocortical nodules in both left and right non-neoplastic adrenals. Peri- and intraadrenal arteries and arterioles demonstrated marked arteriosclerotic vascular changes. Immunoreactivity for several steroidogenic enzymes was present in the tumour and markedly diminished in the non-neoplastic adrenals. This patient with Cushing's adenoma is considered to have developed adrenocortical nodules in the nonneoplastic adrenal possibly as a result of localized compensatory overgrowth of adrenocortical cells in response to ischaemic changes due to arteriopathy. When examining patients with Cushing's syndrome and bilateral adrenal enlargement, the possibility of concomitant adenoma and adrenocortical nodule formation should also be considered in the differential diagnosis

3-Hydroxysteroid Dehydrogenases↗
PubMed1997

Case report: Clinical and virological analyses of a patient positive for hepatitis C virus-RNA by branched DNA assay but negative for anti-hepatitis C virus antibodies.

Infection with hepatitis C virus (HCV) is usually diagnosed by the presence of antibodies against fusion proteins or peptides derived from different regions of the HCV genome. However, a subgroup of patients with HCV viraemia are seronegative for antibody against hepatitis C virus (anti-HCV) by conventional antibody assays. We analysed serum samples from a patient with liver cirrhosis who tested negative for anti-HCV by a second-generation assay, but positive for HCV-RNA by reverse transcription polymerase chain reaction (RT-PCR) and branched DNA signal amplification. To identify possible mutations that could explain the failure of detection of anti-HCV by second-generation assay, PCR-amplified DNA fragments of the core region derived from the serum were cloned and sequenced. Nucleotide (nt) and amino acid (aa) sequence analyses (nt 1-486, aa 1-162) showed no mutations revealing stop codons, frame-shifts, deletions or insertions, but the presence of two amino acid substitutions (aa 75 and 91) when compared with HCV-J, a prototype strain of genotype 1b isolated from a Japanese patient. One of these two mutations (aa 75) was situated in the second hydrophilic domain of the core peptide, but analysis of the hydropathy profile showed only a little change. The two mutations were identical to those identified in other Japanese HCV isolates. The serum immunoglobulin level and T and B cell counts were normal in our patient. Our data suggest that the absence of anti-HCV in this patient was not due to mutations of major epitopes of HCV. Low-dose prednisolone administration just after transfusion may have induced immunological tolerance against HCV in this patient.

Aged↗
PubMed1997

Urocortin expression in human pituitary gland and pituitary adenoma.

Urocortin is a recently identified neuropeptide of the CRF family in the mammalian brain, but its expression in human tissue has been little studied. In this study, we examined urocortin expression in human anterior pituitary gland and pituitary adenomas by RIA, high performance liquid chromatography, immunohistochemistry, messenger ribonucleic acid (mRNA) in situ hybridization, and reverse transcriptase-PCR. Immunoreactive urocortin concentrations in normal pituitary tissue extract were 103.25 +/- 39.05 ng/g wet wt (mean +/- SEM; n = 4), and their levels were all significantly higher than those in other portions of central nervous system of the same subjects. High performance liquid chromatography analysis of human pituitary extract demonstrated a single peak corresponding to that of the expected chromatographic mobility of synthetic human urocortin-(1-40). Urocortin-immunoreactive cells were detected in the anterior pituitary gland. Neither urocortin-immunoreactive nerve fibers nor cells were detected in the posterior lobe. Immunostaining in serial mirror tissue sections revealed that 76.55 +/- 3.06% of urocortin-immunoreactive cells expressed GH immunoreactivity, whereas 22.25 +/- 3.02% and less than 1% of urocortin-immunoreactive cells expressed PRL and ACTH, respectively. mRNA hybridization signals of urocortin were also detected in urocortin-immunopositive pituitary cells. The reverse transcriptase-PCR analysis demonstrated a 145-bp RNA band corresponding to that of the expected length of urocortin in all cases of normal pituitary glands examined (n = 3). We also immunostained urocortin in 52 cases of human anterior pituitary adenomas, including GH-producing adenomas (n = 14), ACTH-producing adenomas (n = 13), PRL-producing adenomas (n = 11), and nonfunctioning hormonally inactive adenomas (n = 14). No urocortin immunoreactivity was detected in these adenoma cells, except for one case of GH-producing adenoma and one case of nonfunctioning adenoma. We also performed mRNA in situ hybridization in 27 adenomas. No hybridization signals were detected in these adenomas, except in two cases. The results described above indicated that urocortin is synthesized in human anterior pituitary cells and may play an important role in biological features of normal pituitary gland, possibly as an autocrine or a paracrine regulator

Adenoma↗
PubMed1997

DNA topoisomerase II alpha and Ki-67 in human adrenocortical neoplasms: a possible marker of differentiation between adenomas and carcinomas.

Cell kinetic information is valuable in evaluating the diagnosis and/or biologic behavior of various human neoplasms. Monoclonal antibody Ki-67 recognizes the cells other than G0 of the cell cycle. A cell cycle-related intranuclear protein, topoisomerase II alpha (topoII alpha), separates chromosomes at the end of mitosis. Its expression is mostly limited to the S to G2/M phases of the cell cycle. We studied cell proliferative activity in adrenocortical adenomas (n = 28), carcinomas (n = 17), and normal adrenal glands (n = 6) by immunohistochemical analysis of Ki-67 and topoII alpha to evaluate their value in the diagnosis of adrenocortical malignancy. We detected Ki-67 and topoII alpha immunohistoreactivity in the nuclei of each case we examined. There was a significant positive correlation (r = 0.927) between the Ki-67 and topoII alpha labeling indexes (LIs), the percentage of positive cells. In normal adrenal cortex and adenoma, the LIs for Ki-67 and topoII alpha were 0.48 +/- 0.16 and 0.44 +/- 0.15 for normal and 0.64 +/- 0.11 and 0.72 +/- 0.12 for adenoma, respectively, with no significant differences in the LIs of adenomas and normal adrenals. The Ki-67 and topoII alpha LIs in the carcinomas were 5.84 +/- 1.33 and 6.13 +/0 1.65, respectively; these LIs were significantly higher than the LIs of adenomas. Eleven of 17 carcinomas demonstrated topoII alpha and Ki-67 LIs of more than 2.5, whereas none of the adenomas did. The topoII alpha and Ki-67 LIs in carcinomas with metastasis (11.21 +/- 3.15 and 9.75 +/- 2.31 respectively; n = 7) were significantly higher than in those without metastasis (2.58 +/- 0.61 and 3.12 +/- 0.90, respectively; n = 10). This indicates that immunohistochemical analysis of Ki-67 and topoII alpha could help to differentiate carcinoma from adenoma in resected adrenocortical neoplasms and might predict aggressive biologic behavior in carcinomas.

Adenoma↗
PubMed1996

A population association study of four candidate genes (hexokinase II, glucagon-like peptide-1 receptor, fatty acid binding protein-2, and apolipoprotein C-II) with type 2 diabetes and impaired glucose tolerance in Japanese subjects.

In order to define the major genetic factor(s) for the development of Type 2 (non-insulin-dependent) diabetes mellitus in Japanese subjects, a population association study of candidate genes involved in either glucose or lipid metabolism was carried out using microsatellite DNA polymorphisms. Each polymorphic locus near the four candidate genes, hexokinase II (HKII), glucagon-like peptide-1 receptor (GLP1R), fatty acid binding protein-2 (FABP-2), and apolipoprotein C-II (apoC-II) genes, were amplified by polymerase chain reaction (PCR) using 32P-labelled primers and each subject was genotyped for the association study. The HKII, GLP1R, FABP-2, and apoC-II polymorphisms exhibited 18, 10, 7, and 10 alleles, respectively. While polymorphism information contents (PICs) of these polymorphisms were relatively high, allele frequencies in these polymorphisms did not differ among subjects with Type 2 diabetes, impaired glucose tolerance (IGT) and non-diabetic controls. These results suggest that the HKII, GLP1R, FABP-2, and apoC-II genes are not the major inherited factors for the development of Type 2 diabetes or IGT in Japanese subjects, although minor contribution cannot be ruled out.

Apolipoprotein C-II↗
PubMed1996

Effects of calcium antagonists on hepatic and systemic hemodynamics in awake portal hypertensive rats.

The effects of the calcium antagonists diltiazem and nicardipine on portal pressure and splanchnic blood flow were studied in awake, unrestrained portal hypertensive rats. Portal hypertension was induced in rats by partial portal vein ligation. Hemodynamic measurements were done using the radiolabeled microsphere technique. In portal vein-ligated and sham-operated rats, intraarterial diltiazem and nicardipine reduced mean arterial pressure. No significant changes, however, were observed in portal pressure and cardiac index. In portal vein-ligated rats, diltiazem and nicardipine increased portal tributary blood flow. Portal tributary vascular resistance was also significantly decreased. The decrease in the hepatocollateral vascular resistance prevented an increase in portal pressure. In sham-operated rats, these changes were not observed. It is possible that the vascular responses to calcium antagonists are altered in portal vein-ligated rats. These findings demonstrate that the hemodynamic effects of calcium antagonists occur at two levels. First, the increase in portal tributary blood flow appears to be a selective effect on portal tributary vascular resistance. Secondly, the portal pressure does not increase in parallel with the increase in portal tributary blood flow because of a similar reduction in portocollateral vascular resistance.

Animals↗
PubMed1996

Effects of acute and chronic ethanol administration on hepatic hemodynamics and hepatic oxygen consumption in awake rats.

BACKGROUND/AIMS AND METHODS: We investigated the effects of acute and chronic ethanol administration on hepatic hemodynamics and hepatic oxygen delivery and consumption in awake rats, using the radiolabeled microsphere technique and measurement of oxygen content in blood. RESULTS: Acute oral and intraarterial ethanol administration produced a significant increase in liver blood flow and hepatic oxygen delivery, but resulted in a significant (25-41%) decrease in hepatic oxygen consumption. These changes lasted up to 5 h after ethanol administration. At 24 h, hepatic oxygen consumption was significantly increased by 33% over control values. During withdrawal in rats fed liquid diets containing alcohol for 6 weeks, hepatic oxygen delivery was maintained at the same level as control pair-fed rats, while hepatic oxygen consumption increased by 28%. Further, in abstinent rats, acute ethanol readministration resulted in a 41% increase in hepatic oxygen delivery but a 32% decrease in hepatic oxygen consumption. CONCLUSIONS: These findings demonstrate, in awake animals, a biphasic response of hepatic oxygen consumption following acute ethanol administration and an increase in hepatic oxygen consumption following chronic ethanol intake. Furthermore, acute ethanol treatment reduced hepatic oxygen consumption in spite of an increase in hepatic oxygen delivery.

Animals↗
PubMed1996

Urinary excretion of pyridinoline and deoxypyridinoline measured by immunoassay in hypothyroidism.

OBJECTIVE: We measured pyridinium cross-links, markers of bone resorption, by an enzyme-linked immunosorbent assay (ELISA) in hypothyroid patients to see whether bone resorption was reduced in hypothyroidism and whether it increased with T4 treatment. DESIGN AND PATIENTS: Eight hypothyroid patients, whose initial TSH levels were 268.1 +/- 87.7 mU/l (mean +/- SE), were treated with T4 (100 micrograms/day). Urinary excretion of pyridinium cross-links was assayed before and after T4 treatment. MEASUREMENTS: Pyrilinks and Pyrilinks-D kits were used. The Pyrilinks assay measures free forms of pyridinoline and deoxypyridinoline together (PYD), while the Pyrilinks-D assay measures deoxypyridinoline (DPD) alone. The Pyrilinks reference ranges for normal subjects are 8-24nmol/mmol creatinine in males and 10-28nmol/mmol creatinine in normal premenopausal females. The DPD reference ranges obtained from normal men and women aged 40-50 years were 3.20 +/- 0.75 (mean +/- SD) nmol/mmol creatinine and 4.55 +/- 1.22 nmol/mmol creatinine, respectively. RESULTS: The sensitivity of the assay was enhanced by simply using less diluted urine samples. Concentrations of both compounds of the urinary pyridinium cross-links were low in untreated hypothyroid patients and increased gradually as thyroid hormone status improved from hypothyroidism to euthyroidism. One month after treatment when the TSH levels in the patients were still as high as 74.4 +/- 44.5 mU/l, urinary PYD excretion has increased to 2.6 times the pretreatment level. When the TSH levels of the patients decreased below 10 mU/l, both PYD and DPD increased significantly to 3.8 and 3.3 times pretreatment values, respectively. CONCLUSIONS: Although hyperthyroidism or excess treatment with thyroid hormone has been known to induce bone resorption, this is the first report that urinary excretion of pyridinium cross-links is reduced in hypothyroidism and is normalized by physiological thyroid hormone replacement.

Adult↗