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Masayuki Hosoi

Publications and source records attributed to Masayuki Hosoi.

13 recordsLinked to original sources
PubMed2003

Role for thromboxane A2 from glomerular thrombi in nephropathy with type 2 diabetic rats.

We used rats (the Otsuka Long-Evans Tokushima Fatty strain) as a model of type 2 diabetes to find whether thromboxane (TX) A2 is involved in diabetic nephropathy, and if so, to identify where it is synthesized. We measured urinary excretion of TXB2 and 2,3-dinor-TXB2 in rats up to 60 weeks of age as markers of renal and platelet synthesis of TXA2, respectively. Some diabetic rats were given daily oral doses of OKY-046 (100 mg/kg), a TXA2 synthase inhibitor, starting when they were 10 weeks of age. Healthy Long-Evans Tokushima Otsuka rats served as the controls. Urinary excretion of protein was greater in diabetic rats at 26 weeks than in controls, and the difference increased with age. Urinary excretion of TXB2 by diabetic rats was about 150% that of controls at 14 weeks, and remained at that level. In diabetic rats, urinary excretion of 2,3-dinor-TXB2 increased with age in parallel to increases in proteinuria, but in controls, excretion of these metabolites did not change with age. In diabetic rats, OKY-046 prevented the increase in urinary excretion of both metabolites, and decreased the proteinuria. Histologic examination at 60 weeks showed intraglomerular thrombi in diabetic rats but not in controls. OKY-046 reduced intraglomerular thrombi formation and the score for glomerulosclerosis. When platelet aggregation began, more TXA2 than before was released from the thrombi that formed, and the TXA2 contributed to the progress of nephropathy in this rat model of type 2 diabetes.

6-Ketoprostaglandin F1 alpha↗
PubMed2003

Treatment of lymphocytic hypophysitis by high-dose methylprednisolone pulse therapy.

A 26-year-old woman 3 months post-partum was admitted to our hospital suffering from gross visual disturbance. Magnetic resonance imaging (MRI) revealed a pituitary mass, extending into the suprasellar cistern, with intense gadolinium enhancement. Lymphocytic hypophysitis (LHy) was suspected, and the patient received high dose methylprednisolone pulse therapy (HDMPT). Her visual disturbance was dramatically ameliorated on the first day following initiation of HDMPT, and MRI revealed marked mass reduction. Her pituitary function recovered 6 months after therapy. This case report suggests that HDMPT proved effective for mass reduction of severe LHy and could obviate the need for a useless surgery.

Adult↗
PubMed2003

Transient central diabetes insipidus in pregnancy with a peculiar change in signal intensity on T1-weighted magnetic resonance images.

A 38-year-old woman was admitted with severe thirst and polyuria at 31 weeks' gestation. The plasma concentration of vasopressin (AVP) was very low (0.73 pg/ml) under conditions of high plasma osmolality (316 mOsm/ kg). T1-weighted magnetic resonance (MR) images revealed enlargement of the pituitary posterior lobe with absence of the hyperintense signal. After delivery, restoration of the hyperintense signal was demonstrated. This depletion-repletion process, which reflects the decrease and increase in amount of neurosecretory granules, is recognized in the case of transient central diabetes insipidus during pregnancy. We consider that an increase in cystine-aminopeptidase (CAP) activity is implicated in the pathogenesis.

Adult↗
PubMed2003

Intrarenal hemodynamic changes after captopril test in patients with type 2 diabetes: a duplex Doppler sonography study.

OBJECTIVE: ACE inhibitors are known to be effective in preventing the progression of diabetic nephropathy. Activation of the renin-angiotensin system (RAS) is reported to contribute to intrarenal hemodynamic abnormality in diabetic patients. We examined whether RAS blockade by captopril induces intrarenal hemodynamic changes in normotensive patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: The patients ranged in age from 40 to 65 years (20 men and 20 women). A total of 15 age- and sex-matched healthy individuals served as control subjects. Resistive index (RI) of interlobar arteries was examined by duplex Doppler sonography before and after the oral captopril (25 mg) test. RESULTS: At baseline, no significant differences in RI values or plasma renin activity (PRA) were seen between the patients and healthy subjects. In healthy subjects, the RI values after the captopril test were significantly higher than baseline values (P < 0.01). However, in patients with type 2 diabetes, both with normoalbuminuria and microalbuminuria, RI values after the test were significantly lower than baseline values (P < 0.001). There were significant negative correlations between DeltaRI value and HbA1c (r = -0.458, P < 0.005) and between DeltaRI value and baseline PRA in diabetic patients (r = -0.339, P < 0.05). Multiple regression analysis showed that HbA1c and baseline PRA significantly and independently affected the magnitude of decrease in RI values after captopril administration in diabetic patients (R2 = 0.391, P < 0.0001). CONCLUSIONS: These results indicate that the intrarenal RAS may be activated in diabetic patients, that such activation may be affected by poor glycemic control, and that blockade of RAS activation by ACE inhibitor reduces intrarenal vascular resistance in diabetic patients. The results emphasize the beneficial effects of ACE inhibition in improving intrarenal hemodynamics in diabetic patients.

Adult↗
PubMed2002

Fibrillar collagen regulation of plasminogen activator inhibitor-1 is involved in altered smooth muscle cell migration.

OBJECTIVE: Vascular smooth muscle cells (SMCs) cultured on polymerized type I collagen fibrils are arrested in the G1 phase of the cell cycle, and their phenotypic markers and pattern of expressed genes are markedly altered. In this study, we examined polymerized collagen regulation of plasminogen activator inhibitor (PAI)-1 and its involvement in SMC migration. METHODS AND RESULTS: We demonstrate that secretion and cell surface accumulation of PAI-1 are suppressed in SMCs cultured on polymerized collagen compared with SMCs cultured on monomer collagen. SMCs replated on vitronectin after culture on monomer collagen result in PAI-1 accumulation at focal adhesions and colocalization with alpha(v)beta3 integrins. In contrast, polymerized collagen inhibits PAI-1 accumulation at focal adhesions when the SMCs are replated on vitronectin. Furthermore, for SMCs cultured on polymerized collagen, platelet-derived growth factor-stimulated migration on vitronectin is enhanced by PAI-1, with its function counteracted by urinary plasminogen activator. Finally, exogenous addition of PAI-1 appears to partly restore platelet-derived growth factor-stimulated alpha(v)beta3-dependent SMC migration that is specifically suppressed by polymerized collagen. CONCLUSIONS: Polymerized type I collagen fibrils dynamically regulate PAI-1, which may be involved in altered alpha(v)beta3 integrin-dependent SMC migration.

Cell Movement↗
PubMed2002

Glycemic response during exercise after administration of insulin lispro compared with that after administration of regular human insulin.

To examine the glycemic response during exercise after administration of short-acting insulin lispro, we compared changes in plasma glucose concentrations during exercise performed by patients with diabetes after the administration of either insulin lispro or regular human insulin. Seven patients with diabetes (two with type 1 and five with type 2) participated in this study. Each of the insulin-depleted subjects received the same number of units of either insulin lispro or regular human insulin, delivered subcutaneously to the abdomen. The next day, each subject received a similar injection of the solution not previously administered. After each injection, the subjects were fed a standard meal of approximately 9 kcal/kg body weight. One hour after eating the test meal, the subjects performed 30 min of cycle ergometer exercise at 50% maximal oxygen uptake. Plasma glucose, insulin, glucagon, growth hormone (GH), and catecholamine concentrations were then measured at specific intervals. Insulin concentrations were higher and peaked earlier after administration of insulin lispro than after administration of regular human insulin. The length of time, needed to reach minimum plasma glucose concentration after exercise was begun, was significantly shorter after administration of insulin lispro, and the percentage of plasma glucose decrease induced by exercise relative to the peak concentration was significantly greater. No differences were found in the concentration changes of counterregulatory hormones between the insulin lispro data and the regular human insulin data. Compared with regular human insulin, insulin lispro induces a more rapid and greater decrease in plasma glucose concentration during exercise because of its faster absorption.

Adult↗
PubMed2002

ecNOS gene polymorphism is associated with endothelium-dependent vasodilation in Type 2 diabetes.

The association between endothelial constitutive nitric oxide synthase (ecNOS) gene polymorphism and vascular endothelial function has not been clarified. We investigated the impact of ecNOS gene polymorphism on endothelial function in 95 patients with Type 2 diabetes (ecNOS genotype: 4b/b, n = 62; 4b/a, n = 30; 4a/a, n = 3). Flow-mediated (endothelium dependent, FMD) and nitroglycerin-induced (endothelium independent, NTG) vasodilations of the right brachial artery were studied using a phase-locked echotracking system. There were no significant differences in clinical characteristics among the ecNOS genotypes. The FMD was significantly lower in the patients with ecNOS4a allele than in those without ecNOS4a allele (P < 0.05). Multiple regression analysis showed that ecNOS4a allele and mean blood pressure were significant independent determinants for reduced FMD in all patients (R(2) = 0.122, P = 0.0025). The ecNOS4a allele was an independent determinant for reduced FMD in smokers but not in nonsmokers. These results suggest that ecNOS4a allele is a genetic risk factor for endothelial dysfunction in diabetic patients, especially in smokers.

Aged↗
PubMed2002

Complete adrenocorticotropin deficiency after radiation therapy for brain tumor with a normal growth hormone reserve.

A 34-year-old man with neurofibromatosis type 1, who had received radiation therapy after the excision of a brain tumor 5 years earlier, was admitted to our hospital with vomiting and weight loss. Cortisol and adrenocorticotropin (ACTH) were undetectable before and after administration of 100 microg corticotropin releasing hormone. The level of growth hormone without stimulation was 24.7 ng/ml. We diagnosed him to have complete ACTH deficiency attributable to radiation therapy. This is the first known case of a patient with complete ACTH deficiency after radiation therapy and a growth hormone reserve that remained normal.

Adrenal Insufficiency↗
PubMed2002

An insulinoma for which secretin test and selective arterial calcium injection test were useful.

A 76-year-old woman suffered from somnolence while fasting for almost 2 years. Fasting plasma glucose (FPG) (40 mg/dl) and the immunoreactive insulin (IRI) level (8.8 microU/ml) were not compatible with Fajan's ratio or Turner's ratio observed in typical insulinoma. The secretin test showed no response to insulin secretion, suggesting the presence of insulinoma. Abdominal dynamic computed tomography (CT) revealed a 12-mm hypervascular lesion in the head of the pancreas. A selective arterial calcium infusion test (SACI) was performed, during which IRI in the hepatic venous blood was measured following selective intraarterial calcium infusion. An increase in IRI levels in the gastroduodenal and superior mesenteric arteries suggested the presence of a functional insulinoma in the head of the pancreas. Enucleation of the tumor improved FPG and IRI levels to 138 mg/dl and 3.8 microU/ml, respectively. After surgery, a secretin test showed a 5-fold increase in IRI levels, suggesting normal beta cell function. This case illustrates the value of the secretin test for the diagnosis of insulinoma and for the postoperative assessment of beta cell function. It further illustrates the value of the SACI for localizing an insulinoma.

Aged↗
PubMed2002

Impact of diabetes on coronary stenosis and coronary artery calcification detected by electron-beam computed tomography in symptomatic patients.

OBJECTIVE: Ischemic heart disease is a pivotal complication for diabetic patients. Electron-beam computed tomography (EBCT) represents the only noninvasive method that allows for accurate quantification of coronary artery calcification that reflects underlying atherosclerotic disease. Although coronary calcium score (CCS) cut points that predict the presence of angiographic stenosis have been established in nondiabetic individuals, it is not known whether coronary calcifications in diabetic patients are associated with the presence of significant coronary stenoses. In this study, we evaluated the relationship between coronary calcifications and angiographic stenosis in symptomatic patients with or without type 2 diabetes. RESEARCH DESIGN AND METHODS: In this study, 282 patients (204 men and 78 women) with chest pain, including 101 diabetic patients and 181 nondiabetic patients (mean age 63 +/- 9.6 years), underwent coronary angiography and EBCT with determination of CCS using Agatston's method. Luminal stenosis >or= 50% was defined as significant coronary stenosis. RESULTS: Angiography identified 205 patients with significant stenoses (89 of 101 diabetic patients, 114 of 181 nondiabetic patients). The sensitivity and specificity of EBCT to detect significant coronary stenosis were not significantly different between diabetic and nondiabetic patients. In diabetic patients, a CCS >or=90 was associated with 75% sensitivity and 75% specificity, whereas a CCS >or=200 was associated with 64% sensitivity and 83% specificity. CONCLUSIONS: We demonstrated that calcification of the coronary arteries in symptomatic diabetic patients is well associated with severity of coronary stenosis, as in nondiabetic patients.

Adult↗
PubMed2002

[Lipid peroxide].

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Biomarkers↗