Yohei Mima

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (6)21.52 Total impact

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    ABSTRACT: Receptor for advanced glycation end products (RAGE) has been shown to be involved in adiposity as well as atherosclerosis even in nondiabetic conditions. In this study, we examined mechanisms underlying how RAGE regulates adiposity and insulin sensitivity. RAGE overexpression in 3T3-L1 preadipocytes using adenoviral gene transfer accelerated adipocyte hypertrophy, whereas inhibitions of RAGE by small interfering RNA significantly decrease adipocyte hypertrophy. Furthermore, double knockdown of high mobility group box-1 and S100b, both of which are RAGE ligands endogenously expressed in 3T3-L1 cells, also canceled RAGE-medicated adipocyte hypertrophy, implicating a fundamental role of ligands-RAGE ligation. Adipocyte hypertrophy induced by RAGE overexpression is associated with suppression of glucose transporter type 4 and adiponectin mRNA expression, attenuated insulin-stimulated glucose uptake, and insulin-stimulated signaling. Toll-like receptor (Tlr)2 mRNA, but not Tlr4 mRNA, is rapidly upregulated by RAGE overexpression, and inhibition of Tlr2 almost completely abrogates RAGE-mediated adipocyte hypertrophy. Finally, RAGE(-/-) mice exhibited significantly less body weight, epididymal fat weight, epididymal adipocyte size, higher serum adiponectin levels, and higher insulin sensitivity than wild-type mice. RAGE deficiency is associated with early suppression of Tlr2 mRNA expression in adipose tissues. Thus, RAGE appears to be involved in mouse adipocyte hypertrophy and insulin sensitivity, whereas Tlr2 regulation may partly play a role.
    Diabetes 09/2012; 62(2). DOI:10.2337/db11-1116 · 8.47 Impact Factor
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    ABSTRACT: Clinical trials demonstrate the effectiveness of cell-based therapeutic angiogenesis in patients with severe ischemic diseases; however, their success remains limited. Maintaining transplanted cells in place are expected to augment the cell-based therapeutic angiogenesis. We have reported that nano-hydroxyapatite (HAp) coating on medical devices shows marked cell adhesiveness. Using this nanotechnology, HAp-coated poly(l-lactic acid) (PLLA) microspheres, named nano-scaffold (NS), were generated as a non-biological, biodegradable and injectable cell scaffold. We investigate the effectiveness of NS on cell-based therapeutic angiogenesis. Bone marrow mononuclear cells (BMNC) and NS or control PLLA microspheres (LA) were intramuscularly co-implanted into mice ischemic hindlimbs. When BMNC derived from enhanced green fluorescent protein (EGFP)-transgenic mice were injected into ischemic muscle, the muscle GFP level in NS+BMNC group was approximate fivefold higher than that in BMNC or LA+BMNC groups seven days after operation. Kaplan-Meier analysis demonstrated that NS+BMNC markedly prevented hindlimb necrosis (P<0.05 vs. BMNC or LA+BMNC). NS+BMNC revealed much higher induction of angiogenesis in ischemic tissues and collateral blood flow confirmed by three-dimensional computed tomography angiography than those of BMNC or LA+BMNC groups. NS-enhanced therapeutic angiogenesis and arteriogenesis showed good correlations with increased intramuscular levels of vascular endothelial growth factor and fibroblast growth factor-2. NS co-implantation also prevented apoptotic cell death of transplanted cells, resulting in prolonged cell retention. A novel and feasible injectable cell scaffold potentiates cell-based therapeutic angiogenesis, which could be extremely useful for the treatment of severe ischemic disorders.
    PLoS ONE 04/2012; 7(4):e35199. DOI:10.1371/journal.pone.0035199 · 3.53 Impact Factor
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    ABSTRACT: A recent clinical trial showed the preventive effect of cilostazol on cerebrovascular diseases. We compared the effects of cilostazol with aspirin on circulating endothelial progenitor cells (EPCs), a surrogate marker for cardiovascular disease, and lipid metabolism in a randomized controlled trial (UMIN000000537). Forty-nine diabetic outpatients with leukoaraiosis or asymptomatic old cerebral infarction were enrolled in the study with written informed consent. They were randomly assigned to a cilostazol (200 mg daily, n= 24) or aspirin group (100 mg daily, n= 25), and followed for 16 weeks. Changes in circulating CD34(+) CD45(low) CD133(+) VEGFR2(+) EPCs (ΔEPC) were a primary endpoint. Changes in CD34(+) CD45(low) CD133(+) progenitor cells (ΔPC), p-selectin-positive platelet, platelet-monocyte binding measured by flow cytometry, LDL-, HDL-, small dense LDL (sdLDL)-cholesterol and triacylglycerol were the secondary endpoints. Twenty patients in each group completed the study. ΔEPC were significantly higher in the cilostazol group than aspirin group at 16 weeks, while ΔPC were already significantly higher at 4 weeks in the cilostazol group. Changes in p-selectin-positive platelets and platelet-monocyte binding were similar in both groups. The cilostazol group showed significantly less sdLDL- and higher HDL-cholesterol than the aspirin group at both 4 and 16 weeks. ΔEPC were significantly and inversely correlated with changes of sdLDL, while positively with those of HDL. Analysis of covariance showed that a significant relation of ΔEPCs with cilostazol treatment was confounded by changes in HDL- and sdLDL-cholesterol. Cilostazol increases circulating EPCs and decreases small-dense LDL in diabetic patients with cerebral ischemia.
    Journal of atherosclerosis and thrombosis 06/2011; 18(10):883-90. DOI:10.5551/jat.9225 · 2.77 Impact Factor
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    ABSTRACT: Diabetic autonomic neuropathy (DAN) is thought to reduce skin nutritive perfusion through increase of arteriovenous shunting flow, resulting in foot ulceration. However, the correlation between skin tissue oxygenation and DAN has not been fully elucidated. Transcutaneous oxygen tension (TcPO2) is a reliable indicator of skin nutritional microcirculation. The aim of this study was to evaluate the influence of DAN on skin microcirculation by using TcPO2 measurements. The resting TcPO2 (REST-TcPO2) and post-exercise TcPO2 (Ex-TcPO2) of the calf and dorsalis pedis regions were measured simultaneously in 52 patients (104 limbs), including 41 diabetes patients. All patients underwent angiography, and the presence of arterial stenosis was evaluated. TcPO2 levels were compared among the groups of patients with no neuropathy, sensory neuropathy alone, and DAN. In both the calf and dorsalis pedis regions, Ex-TcPO2 levels in diabetes patients with DAN were significantly lower than those in diabetes patients without any neuropathy. However, there was no difference in REST-TcPO2 levels among these groups. We then performed multiple regression analysis to evaluate the influence of DAN on each TcPO2 after adjustment for multiple clinical factors. DAN was a significant determinant of REST- and Ex-TcPO2 in the calf region, and it was independent of arterial stenosis and sensory neuropathy. In contrast, DAN was not an independent determinant of REST- and Ex-TcPO2 in the dorsalis pedis region. We, for the first time, showed that DAN has significant effects on skin microcirculation of the calf region but not of the dorsalis pedis region.
    Osaka city medical journal 12/2010; 56(2):27-36.
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    ABSTRACT: Receptor for advanced glycation end-products (RAGE) has been shown to be involved in cardiovascular diseases. We examined the involvement of RAGE in atherosclerosis under non-diabetic status, and its relation to the effect on adiposity. Apolipoprotein E (apoE)(-/-)RAGE(+/+) or apoE(-/-)RAGE(-/-) mice were fed with an atherogenic diet or the standard chow diet. Adiposity was determined by weight of epididymal adipose tissue, adipocyte size and serum adiponectin. Aortic atherosclerosis was morphometrically determined. ApoE(-/-)RAGE(-/-) mice exhibited significantly less total aortic plaque area than apoE(-/-)RAGE(+/+) mice. Body weight, epididymal fat weight, and epididymal adipocyte size were also significantly less in apoE(-/-)RAGE(-/-) mice than apoE(-/-)RAGE(+/+) mice. Serum adiponectin, but not tumor necrosis factor-alpha, was significantly higher in apoE(-/-)RAGE(-/-) mice than apoE(-/-)RAGE(+/+) mice. Simple regression analysis revealed that the total aortic plaque area was positively associated with epididymal fat weight, epididymal adipocyte size, and negatively with serum adiponectin levels. Multiple regression analyses revealed that RAGE genotype and serum adiponectin were mutually interrelated in determining aortic atherosclerosis. Finally, immunohistochemical and real-time RT-PCR analyses revealed that RAGE was indeed expressed in both adipocytes and endothelial cells in epididymal adipose tissue. RAGE-mediated regulation of adiposity in non-diabetic status could be attributable to the progression of atherosclerosis.
    Atherosclerosis 04/2010; 211(2):431-6. DOI:10.1016/j.atherosclerosis.2010.04.006 · 3.97 Impact Factor
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    ABSTRACT: Despite the clinical usefulness of transcutaneous oxygen tension (TcPO(2)) to assess the severity of limb ischemia, the factors determining TcPO(2) in patients with peripheral arterial disease (PAD) have not been fully clarified. We therefore examined the regions of arterial stenosis and clinical factors affecting lower-extremity TcPO(2). Resting TcPO(2) (REST-TcPO(2)) and postexercise TcPO(2) (Ex-TcPO(2)) in the calf region and the dorsalis pedis were measured simultaneously in 66 patients (132 limbs) with clinically suspected PAD, in whom angiography was also performed. The peripheral arteries of the lower extremities were divided into five segments, and the impact of significant stenosis in each segment on ipsilateral TcPO(2) was evaluated by multiple regression analysis. In the calf region, significant stenosis of the proximal arteries (common-external iliac artery) revealed stronger involvement determining Ex-TcPO(2) than the peripheral segment (posterior tibial artery). In the dorsalis pedis, the peripheral segment (anterior tibial artery) more strongly determined Ex-TcPO(2) and REST-TcPO(2) than proximal segments. Age, creatinine, and diabetes were associated with REST-TcPO(2) of the calf region independent of arterial stenoses, while those of the dorsalis pedis were independently associated with age, and creatinine. In contrast, Ex-TcPO(2) in both regions was not independently associated with clinical factors, except for stenosis of the perfusing arteries. The vascular lesions affecting TcPO(2) differ between the calf region (proximal > peripheral) and the dorsalis pedis (proximal < peripheral). In addition postexercise TcPO(2) is solely determined by stenosis of the perfusing arteries, while TcPO(2) at rest is affected by multiple clinical factors.
    Journal of atherosclerosis and thrombosis 03/2010; 17(8):858-69. DOI:10.5551/jat.3723 · 2.77 Impact Factor