Kenzo Iino

Peroxisome proliferator-activated receptor γ1 (PPARγ1) expresses in rat mesangial cells and PPARγ agonists modulate its differentiation

Thiazolidinediones, synthetic ligands of peroxisome proliferator-activated receptor gamma (PPARgamma), are reported to have direct beneficial effects on diabetic nephropathy without lowering blood glucose levels in human and rat. We hypothesized these effects of thiazolidinediones might be derived from PPARgamma activation of kidney cells, and we examined the expression of PPARgamma and the effect of PPARgamma agonists, troglitazone and 15-deoxy-delta-prostaglandin J2 (15d-PGJ2), on the proliferation and differentiation in rat mesangial cells. A single band of mRNA of PPARgamma with a predicted size was detected in reverse transcription-polymerase chain reaction products (RT-PCR) using established PCR probes of PPARgamma. PPARgamma protein in rat mesangial cells was identified as PPARgamma1 by a Western blot. In a gel mobility shift assay to determine a binding activity of PPARgamma, the nuclear protein from rat mesangial cells bound to a (32)P-labeled oligonucleotide probe, including PPAR response elements. A synthetic and a natural ligand of PPARgamma, troglitazone and 15d-PGJ2, decreased thymidine incorporation in a dose dependent manner. After 7 days incubation with troglitazone and 15d-PGJ2, alpha-smooth muscle actin expression, a marker of mesangial cell de-differentiation, was decreased significantly compared to that of control. These results indicate that PPARgamma1 is expressing in rat mesangial cells, and PPARgamma1 activation with its agonists modulates the proliferation and differentiation of cultured rat mesangial cells.

Advanced glycosylation end products induced tissue factor expression in human monocyte-like U937 cells and increased tissue factor expression in monocytes from diabetic patients

Tissue factor (TF) plays a central role in the initial activation of the extrinsic coagulation pathway and is thought to be involved in the development of atherosclerosis and thrombosis. The effect of advanced glycosylation end products (AGEs) on TF expression and its mechanism were assessed by flow cytometric analysis. Human macrophage-like U937 cells, which were shown to contain mRNA encoding the receptors of advanced glycosylation end products (RAGE), expressed TF in a dose-dependent manner on incubation with AGE-albumin. AGE-albumin-induced TF expression was completely inhibited by the anti-oxidant agents, catalase and probucol. TF expression in peripheral monocytes from normal volunteers was also increased by AGE-albumin. Finally, TF expression in monocytes from individuals with diabetes mellitus, in whom the concentration of circulating AGEs is reported to be increased, was higher than that in monocytes from normal controls. These results suggest that AGE-induced TF expression in macrophages/monocytes is mediated by oxidant stress. AGEs may promote thrombosis and the development of atherosclerosis by inducing TF expression in monocytes in patients with diabetes mellitus.

Dilazep and fenofibric acid inhibit MCP-1 mRNA expression in glycoxidized LDL-stimulated human endothelial cells

We previously reported that glycoxidized low-density lipoprotein (glycoxidized LDL) enhanced monocyte chemoattractant protein-1 (MCP-1) mRNA expression through activation of nuclear factor-kappaB (NF-kappaB). Here we investigated the effects of dilazep, an anti-platelet agent, and fenofibric acid, an active metabolite of fenofibrate, on glycoxidized low-density lipoprotein-(LDL)-enhanced MCP-1 mRNA expression. Both 10 microg/ml dilazep and 100 microM fenofibric acid abrogated MCP-1 mRNA expression. ZM241385, an A2a adenosine receptor antagonist, partially inhibited the suppressive effect of dilazep. NF-kappaB activity was also suppressed by 1 microg/ml dilazep and 10 microM fenofibric acid. The antioxidative activity of these drugs on glycation to native LDL or oxidation to glycated LDL was measured using lipid peroxidation and lyso-phosphatidylcholine contents in LDL. Dilazep but not fenofibric acid exhibited antioxidative activity. Although the mechanisms of anti-atherogenic effects of the two drugs on glycoxidized LDL are different, both dilazep and fenofibric acid could potentially prevent atherosclerosis in diabetes mellitus.

Circadian blood pressure variation in non-insulin-dependent diabetes mellitus with nephropathy

We studied a circadian blood pressure variation in relation to the progression of diabetic nephropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). Age, duration of diabetes, body mass index and glycemic control did not differ among the groups of patients with normo-, micro- and macroalbuminuria. None of the patients received antihypertensive drugs. There were no differences in renal and autonomic functions between normo- and microalbuminuric groups, but these functions were impaired in the macroalbuminuric group. The rise in blood pressure was more apparent in 24-h ambulatory blood pressure (AMBP), especially during night-time, as compared with casual blood pressure. Such blood pressure rise was in accordance with the progression of nephropathy. However, pulse rate did not differ among the three groups. The nocturnal fall in blood pressure was blunted in the micro- and macroalbuminuria groups, but evident in the normoalbuminuric group. In the latter, daytime systolic blood pressure (SBP) was significantly higher than night-time SBP (123 +/- 5 mmHg vs. 113 +/- 3 mmHg, P = 0.002). In contrast, in the former two groups of patients, there were no significant differences in SBP between daytime and night-time (134 +/- 9 mmHg vs. 134 +/- 9 mmHg, ns, for microalbuminuria and 159 +/- 8 mmHg vs. 165 +/- 7 mmHg, ns, for macroalbuminuria). Urinary albumin excretion was significantly correlated with night-time SBP (r = 0.48, P = 0.015), but not with daytime SBP (r = 0.30, ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Normalization of glucose entry under the high glucose condition by phlorizin attenuates the high glucose-induced morphological and functional changes of cultured bovine retinal pericytes

We previously reported that sodium-dependent glucose uptake is present in bovine retinal pericytes and that phlorizin normalizes its glucose consumption under high glucose conditions. To clarify the effect of phlorizin on morphological and functional change of retinal pericytes under high glucose conditions, retinal pericytes were incubated in media with 5 mM glucose, 30 mM glucose, and 30 mM glucose plus 0.2 mM phlorizin for 7 days. The diameter of cells in the concentrations of glucose more than 10 mM were significantly larger than those in 5 mM glucose and 30 mM glucose plus phlorizin. Glucose, sorbitol and fructose contents of the cells in 30 mM glucose were significantly increased compared with those in 5 mM glucose, and were normalized by phlorizin. Thymidine uptake in the concentrations of glucose more than 20 mM was significantly decreased compared with that in 5 mM glucose. Myoinositol uptake, and DNA in 30 mM glucose were significantly reduced, and were normalized with phlorizin. Myoinositol content in 30 mM glucose was the same as that in 5 mM glucose, but was significantly decreased by phlorizin. The ratios of glucose to sorbitol or fructose in 30 mM glucose were significantly decreased, compared with those in 5 mM glucose and 30 mM glucose plus phlorizin. Therefore, the cellular enlargement and decreased DNA synthesis in cultured bovine retinal pericytes with abnormal glucose metabolism under high glucose conditions are attenuated by phlorizin, independent of the cellular myoinositol content.

Reduced tissue oxygenation and its reversibility by glycemic control in diabetic patients

Relationship of transcutaneous oxygen pressure (TcP(O2)) to glycemic control and diabetic complications was investigated in patients with non-insulin dependent diabetes mellitus. TcP(O2) was measured in 103 patients with non-insulin dependent diabetes mellitus. Correlation of TcP(O2) to HbA1c, fasting blood sugar (FBS), age, duration of diabetes, serum lipids, hypertension, and diabetic complications were examined. We divided the patients into three groups according to their glycemic control: good control group (HbA1c < 7.0%), fair control group (HbA1c, 7.0-8.9%) and poor control group (HbA1c > or = 9.0). We compared TcP(O2) of these three groups with 19 non-diabetic controls. In 103 patients, TcP(O2) at baseline correlated with HbA1c, FBS and age (P < 0.001, P < 0.01 and P < 0.05, respectively), but did not correlate with duration of diabetes mellitus, neuropathy, nephropathy or retinopathy. TcP(O2) of good and fair control group was not reduced comparing to the non-diabetic control (63 +/- 11, 59 +/- 10 and 64 +/- 12 mmHg, respectively). The poor control group had significantly reduced TcP(O2) (55 +/- 10 mmHg) comparing to non-diabetic control (P < 0.005) and good control group (P < 0.005). Furthermore, in an independent study, TcP(O2), arterial oxygen pressure (Pa(O2)), oxygen pressure of dorsal pedal vein (PV(O2)) and erythrocyte 2,3-diphosphoglycerate (2,3-DPG) in eight patients with poor glycemic control were followed prospectively. Six patients with improvement of glycemic control showed a significant increase of TcP(O2) and Pa(O2) (P < 0.001 and P < 0.005, respectively). However, two patients without improvement of hyperglycemia had no change in TcP(O2) and Pa(O2). PV(O2) and 2,3-DPG levels of erythrocytes were not changed in six patients. These findings suggest that tissue oxygenation in diabetic patients was deteriorated in relation to hyperglycemia and was reversed with glycemic control. Improvement of Pa(O2) might contribute partly to the increase of TcP(O2).

EFFECT OF NICARDIPINE VERSUS ENALAPRIL ON PLASMA ENDOTHELIN-1 IN HYPERTENSIVE PATIENTS WITH TYPE 2 DIABETES MELLITUS

We compared the effects of dihydropyridine type Ca channel blocker slow-release nicardipine and angiotensin converting enzyme inhibitor enalapril on plasma endothelin-1 (ET-1) levels in hypertensive type 2 diabetic patients (n = 20). Nicardipine or enalapril was administered for 6 months by a crossover design. Nicardipine and enalapril comparably lowered blood pressure. Enalapril significantly reduced urinary albumin excretion in microalbuminuric patients, whereas nicardipine did not. Urinary β2-microglobulin excretion was significantly increased during nicardipine treatment. However, both drugs significantly reduced plasma ET-1 as compared with pretreatment levels, close to that in healthy control (2.9 ± 0.3 pg/ml in control, 4.8 ± 0.3 pg/ml before treatment, 3.2 ± 0.3 pg/ml during nicardipine vs before treatment p<0.05, 2.9 ± 0.4 pg/ml during enalapril vs before treatment p<0.01). The decrease in plasma ET-1 was significantly correlated with the increase in natriuresis in normoalbuminuric patients treated with enalapril (r=−0.82, p<0.01) but not in those treated with nicardipine. Although nicardipine and enalapril had different renal effects, both drugs equally suppressed plasma ET-1 levels in hypertensive patients with type 2 diabetes.

Serum high-molecular weight adiponectin is related to early postprandial glycemic increases and gastric emptying in patients with type 2 diabetes mellitus.

Postprandial hyperglycemia and hyperlipidemia are frequently associated with type 2 diabetes mellitus. The aim of the present study is to investigate the clinical determinants of postprandial glycemia and lipemia, especially serum high‐molecular weight adiponectin.

Prospective Study of Asymmetric Retinopathy as a Predictor of Brain Infarction in Diabetes Mellitus

hypothalamus (4). The IGF-I levels were not statistically different between regimens and, if anything, tended to be lower on intraperitoneal insulin making it highly unlikely that IGF-1 would be mediating any decrease in our patients GH profile. IGFBP-l appears to have an inhibitory effect on IGF-I action in various tissues (6), and it has been suggested that increased amounts of this binding protein inhibit the detection of IGF-1 by the hypothalamus and/or pituitary gland (5). Suppressing IGFBP-l levels with direct intraperitoneal (intraportal) insulin administration may allow improved detection of IGF-I by the pituitary or hypothalamus and subsequently lead to a decreased GH secretion. This case report highlights a possible benefit of insulin delivery via the intraperitoneal route. These preliminary findings need, however, to be examined in larger studies and over longer time intervals. If the marked increase of IGFBP-l known to occur in type I diabetes can be more effectively suppressed by using intraperitoneal insulin this may provide particular benefit to adolescent diabetic patients as elevated levels of IGFBP-l have been postulated to play a role in the growth impairment seen in these patients (7).

Nateglinide may increase high-molecular weight adiponectin in type 2 diabetic patients with hypoadiponectinemia.

We studied the effects of nateglinide on serum adiponectin in 26 patients with type 2 diabetes mellitus. The changes in serum insulin at 30min significantly correlated with those in serum high-molecular weight adiponectin. Nateglinide may ameliorate hypoadiponectinemia as well as postprandial hyperglycemia in patients with type 2 diabetes mellitus.