Biomedical subjects

Yoshito Oshiro

Publications and source records attributed to Yoshito Oshiro.

4 recordsLinked to original sources

PubMed2004

Fluvastatin improves endothelial dysfunction in overweight postmenopausal women through small dense low-density lipoprotein reduction.

Small dense low-density lipoprotein (sdLDL), which are often associated with obesity, are considered as the most atherogenic and have been shown to impair endothelial function. It is not known whether reduction of sdLDL by pharmacological intervention can improve endothelial function. Thirty-four consecutive postmenopausal women with >/=5.70 mmol/L total cholesterol were placed into either an overweight (body mass index [BMI] >/= 25.0, n = 22) or a normal-weight (BMI < 25.0, n = 12) group, and forearm blood flow (FBF) was measured using strain-gauge plethysmography during reactive hyperemia before and after fluvastatin treatment. At baseline, the peak FBF during reactive hyperemia in the overweight group was less than that in the normal-weight group (mean +/- SD, 13.6 +/- 4.4 v 22.2 +/- 4.0 mL/min/100 mL, P <.01). The maximal FBF after nitroglycerin was similar in both groups. In the stepwise multiple regression analysis, only the concentration of sdLDL was the predictor for peak FBF (standard coefficient = -0.517, P =.0115). The nonsignificant parameters for the correlations in the model were age, BMI, systolic blood pressure, the homeostasis model assessment of insulin resistance (HOMA-IR), hemoglobin A(1c) (HbA(1c)), and LDL-cholesterol. Fluvastatin treatment was associated with the recovery of the peak FBF in the overweight group but it did not influence that of the normal-weight group. Changes in sdLDL fractions by fluvastatin correlated well with the peak FBF recovery. These results suggested that an increased sdLDL was linked to endothelial dysfunction in overweight postmenopausal women and fluvastatin treatment improved endothelial dysfunction by decreasing the atherogenic sdLDL fraction in this population.

Aged↗

PubMed2004

Cilostazol, a phosphodiesterase inhibitor, reduces microalbuminuria in the insulin-resistant Otsuka Long-Evans Tokushima Fatty rat.

We evaluated association between hyperinsulinemia/insulin resistance and microalbuminuria in the insulin-resistant Otsuka Long-Evans Tokushima Fatty (OLETF) rat. OLETF rats showed glomerular hyperfiltration (an increase in creatinine clearance and a decrease in fractional excretion of Na) and microalbuminuria at the insulin-resistant prediabetic stage, and both were related to expression of transforming growth factor (TGF)-beta(1) and extracellular matrix protein such as fibronectin and collagen (a(1)) IV. Cilostazol, a selective type III cyclic nucleotide phosphodiesterase (PDE) inhibitor, normalized glomerular hyperfiltration and microalbuminuria with a parallel decline of TGF-beta(1) and extracellular matrix protein mRNA expression. Cilostazol may be beneficial to lessen early glomerular nephropathy in a state of hyperinsulinemia/insulin resistance.

Albuminuria↗

PubMed2003

Hypoadiponectinemia is closely linked to endothelial dysfunction in man.

Vascular endothelial dysfunction has been demonstrated in overweight or obese patients, but the molecular basis for this link has not been clarified. We asked what the relationship was between adiponectin, an adipose-specific molecule, and endothelial function. Forearm blood flow (FBF) was measured during reactive hyperemia by using strain-gauge plethysmography in 76 Japanese subjects without a history of cardiovascular or cerebrovascular disease, diabetes mellitus, hepatic, or renal disease. The peak FBF and total reactive hyperemic flow [flow debt repayment (FDR)] during reactive hyperemia were correlated with waist circumference (r = -0.418 and -0.414, respectively) and body mass index (r = -0.597 and -0.626, respectively). After correcting for age, gender, and body mass index, the peak FBF was correlated with systolic blood pressure (r = -0.294; P = 0.010), free fatty acid (FFA) (r = -0.331; P = 0.004), and adiponectin in log 10 (r = 0.492; P < 0.001), and FDR was correlated with adiponectin in log 10 (r = 0.462; P = 0.001). In stepwise multiple regression analyses, predictive variables for peak FBF were adiponectin in log 10 (r = 0.468) and FFA (r = -0.292; r(2) = 0.487; P < 0.0001); and predictive variables for FDR were adiponectin in log 10 (r = 0.474) and FFA (r = -0.275; r(2) = 0.346, P < 0.0001). Endothelial function was impaired in proportion to the severity of obesity, and the level of severity was closely related to plasma adiponectin levels. Adiponectin may play a protective role against the atherosclerotic vascular change, and loss of effects enhances endothelial dysfunction, as in obese people.

Adiponectin↗

PubMed2002

Evidence for a deficient pancreatic beta-cell response in a rat model of hyperthyroidism.

To clarify mechanism behind the abnormal glucose tolerance, observed in hyperthyroidism, we studied genomic and nongenomic effects of thyroid hormone on insulin secretion using a rat model of hyperthyroidism. Male Sprague-Dawley rats were intraperitoneally injected with vehicle, low (100 microg/kg) or high dose (600 microg/kg) of thyroxin (T(4)) for 2 weeks. Rats treated with high dose, but not low dose, of T(4), showed an increase in serum T(3) levels, and a decrease in body weight as compared to control rats. In rats treated with either dose of T(4), fasting blood glucose levels were increased, but serum insulin levels were similar to those of controls. After an oral glucose load, blood glucose levels were increased in rats treated with high dose, but not low dose, of T(4). Serum insulin levels after the oral glucose load were decreased in rats treated with either dose of T(4). After an intravenous glucose load, blood glucose levels were comparable among groups, but serum insulin levels tended to be low in T(4)-treated rats. Steady-state blood glucose levels were comparable among groups. The insulin secretory responses to high glucose (20mM) or arginine (10mM) of the isolated pancreas was decreased in rats treated with high dose, but not low dose, of T(4). Mean insulin secretory response to glucose and arginine were decreased by 40.1% and by 60.4% in high-dose-T(4)-treated rats. Addition of T(3) in the perfusion medium decreased glucose-induced insulin release. Ratios of proinsulin mRNA levels to beta-actin mRNA were decreased in the islets of T(4)-treated rats (0.45 +/- 0.07 vs control 0.61 +/- 0.03, p < 0.05). Levels of TR (thyroid hormone nuclear receptor) alpha1 + cErb Aalpha2 mRNA, but not TRbeta1, were decreased in the pancreatic islets of T(4)-treated rats. Calculated islet area was increased, but the number of beta-cells determined immunohistochemically was not increased in T(4)-treated rats, nor the volume density of insulin positive islets. We concluded that a deficient pancreatic beta-cell response to glucose, rather than insulin resistance, was responsible for abnormal glucose tolerance in this model of hyperthyroidism. Thyroid hormone causes a decrease in glucose-induced insulin secretion. We observed nongenomic and genomic effects of thyroid hormone on glucose-induced insulin secretion.

Animals↗