Akihiro Sekikawa

Increase of serum phosphatidylcholine hydroperoxide dependent on glycemic control in type 2 diabetic patients

In order to clarify the relationship between serum phosphatidylcholine hydroperoxide (PCOOH) levels and blood glucose control in type 2 diabetes patients (DM), DM (n = 61) and normal control (n = 11) were enrolled. High-density lipoprotein (HDL) was separated from serum by the addition of sodium phosphotungstate and magnesium chloride, and the precipitated fraction was prepared as non-HDL. Phospholipids were extracted from whole serum, non-HDL and HDL to estimate PCOOH level with chemiluminescence high performance liquid chromatography (CL-HPLC). PCOOH level (nmol/l, mean +/- S.D.) was higher in DM than in control (33.1 +/- 9.5 vs. 23.0 +/- 8.2 for serum; P < 0.01, 17.0 +/- 5.5 vs. 10.6 +/- 3.8 for non-HDL; P < 0.01, and 16.1 +/- 6.3 vs. 12.3 +/- 5.5 for HDL; not significant, respectively). DM was divided into five groups according to hemoglobin A(1c) (HbA(1c)) levels (%): (1) less than 6, (2) 6-6.4, (3) 6.5-6.9 (4) 7.0-7.4, and (5) over than 7.5. Increase of PCOOH levels was dependent on HbA(1c). We concluded that (1) serum and non-HDL PCOOH increased in DM, (2) the level was strongly correlated with diabetic control, and (3) approximately a half amount of serum PCOOH was present in HDL of both control and DM.

Human Arterial Smooth Muscle Cell Proliferation in Diabetes

In the present study, we focus on the proliferation of human arterial smooth muscle cells (SMCs) from NIDDM patients (DM-SMCs) to clarify the reactivity to the growth factor(s) in fetal calf serum (FCS) and the factors) secreted by T-cells. The proliferation of DM-SMCs was significantly greater than SMCs from nondiabetic patients (nonDM-SMC). DM-SMC conditioned medium (DM-condMed) increased the growth of nonDM-SMCs. These results suggest that the growth factor is secreted from DM-SMCs as an autocrine system, which increases the proliferation of nonDM-SMCs. T-cells increased DNA synthesis of SMCs, and DM-SMCs strikingly reacted to T-cells. The present results support a function of T-cells in stimulating SMC growth. In conclusion, human arterial SMC proliferation is increased in diabetes in the same fashion as in experimentally induced diabetes in animals through responses to growth factors and an increased autocrine system. These results provide a mechanism for the increase in atherosclerotic disease in diabetes.

Anti-angiogenic effect of TGFβ in aqueous humor

Abstract Neovascularization is mediated by various factors in ocular tissues. Recent studies have emphasized the role of vascular endothelial growth factor in the induction of angiogenesis. We have previously reported that aqueous humor (AH) suppressed vascular endothelial cell growth and angiogenesis. We speculated that the anti-angiogenic effect of AH is mediated by transforming growth factor beta (TGFβ). In order to clarify the presence of TGFβ in bovine AH, we applied it on the heparin-sepharose affinity column and prepared two fractions (bound and unbound fractions). We measured TGFβ concentration in each fraction and examined how the anti-TGFβ antibody decreased the inhibitory effect of AH on human umbilical vein endothelial cell growth and on in vitro angiogenesis. We found the presence of TGFβ2, but not TGFβ1, in the heparin bound fraction, and the inhibitory effect was detected in the heparin-bound fraction. Anti-TGFβ antibody completely and dose-dependently extinguished the inhibitory effect of AH. We propose that the inhibitory effect of AH on endothelial cell growth and in vitro angiogenesis are both mediated by TGFβ2. Our results indicate TGFβ2 is normally present in AH and protects the eye tissue against abnormal neovascularization.

Plasma phosphatidylcholine hydroperoxide concentrations in normal subjects and patients with hyperlipidemia

In order to examine the basal lipid peroxide level in the plasma of hyperlipidemia, phosphatidylcholine hydroperoxide (PCOOH) as a primary oxidation product of phosphatidylcholine which locates in the surface of lipoproteins was quantitatively determined with chemiluminescence-high performance liquid chromatography (CL-HPLC). Age-related significant increase of plasma PCOOH was present in both hyperlipidemia and normal control. The plasma PCOOH level of hyperlipidemia was significantly higher than that of normal plasma. Among three hyperlipidemic phenotypes, such as hypercholesterolemia ( II a), hypertriglycridemia (IV), and combined hyperlipidemia ( II b), no difference was observed in the plasma PCOOH levels.We propose that the measurement of plasma PCOOH would be useful for evaluate the oxidative stress in vivo.