Recent studies revealed favorable para- and/or autocrine effects of IGF-1 in the pathogenesis of diabetic complications. On the other hand, hyperglycemia is a risk factor for the development of diabetic vascular complications. In this study we examined the effects of high glucose and/or IGF-1 on cell migration and angiogenesis (tubular formation) by using human endothelial cells (EC) in vitro. First we examined cell migration by the two-chamber method. Chronic treatment with a high concentration of D-glucose strongly stimulated the cell migration, which was mimicked by PMA, a protein kinase C (PKC) agonist. The cell migration was also induced by IGF-1. The glucose-induced cell migration was blocked by PKC inhibitor, H7. IGF-1-induced cell migration was not blocked by PD98059, MAPK/ERK kinase (MEK) inhibitor or wortmannin, a phosphatidylinositol (PI) 3-kinase inhibitor. Next we examined the effects of high glucose and/or IGF-1 on the tubular formation of EC. The tubular formation was induced only when the cells were exposed to a combination of high glucose and IGF-1. The tubular formation was blocked by MEK inhibitor and PI 3-kinase inhibitor but not by PKC inhibitor. These results indicate that hyperglycemia and IGF-1, respectively, stimulate the EC migration, and tubular formation is induced by a combination of IGF-1 and hyperglycemia.

In view of the interesting properties of branched polysaccharides occurring in nature, biological activities of nonnatural branched chitins having beta-1,6-N-acetyl-D-glucosamine branches on the poly(beta-1,4-N-acetyl-D-glucosamine) backbone have been studied. The immunostimulatory activities of the branched chitins were determined and compared with those of lentinan, a beta-1,3-D-glucan having beta-1,6-D-glucose branches, using the mouse macrophagelike cell line RAW264.7 in vitro. The secretions of the tumor necrosis factor and nitric oxide proved to be significantly higher with the branched chitins than with lentinan. Moreover, when interferon-gamma was used in conjunction with the branched chitins on macrophage treatment, a marked augmentation of nitric oxide production was observed. These results are interpreted as the direct stimulation of macrophages by the branched chitins, and the distinctive activities suggest the possibility of developing new types of polysaccharide antitumor agents.

Effects of highd-glucose and insulin on the endothelial cell migration and tubular formation were investigated with the use of ECV304 cells, a clonal human umbilical cord endothelial cell line. Exposure of the cells to highd-glucose resulted in a marked increase in the migration, which was blocked by inhibitors of protein kinase C such as H7 (10 μM) and GF109203X (200 nM). Furthermore, a protein kinase C agonist, phorbol 12-myristate 13-acetate, had an effect similar to that of glucose on ECV304 cells. Glucose stimulation of the migration was additively enhanced by 100 nM insulin, and the insulin effect was found to be unaffected by either PD-98059 or wortmannin, a mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase inhibitor and a phosphatidylinositol 3-kinase inhibitor, respectively. Neither did H7 inhibit insulin stimulation of the migration. In contrast, a combination of high d-glucose and insulin, rather than either one alone, promoted tubular formation, which was inhibited by addition of 10 μM PD-98059. Stimulation of ECV304 cells by the combination of highd-glucose and insulin also caused an activation of MAPK, which was again obliterated by the same concentration of PD-98059. In conclusion, human endothelial cell migration and tubular formation are stimulated by highd-glucose and insulin in different ways. In the former reaction, either is effective, a combination of the two results in an additive effect, and activation of protein kinase C is involved. In contrast, tubular formation will only occur in the presence of a combination of highd-glucose and insulin, and MAPK plays an essential role.

This study was performed to examine the effect of rutin in buckwheat noodle on lipid metabolism in rats fed a high-fat, high-sucrose diet. Buckwheat noodles were prepared by traditional Japanese methods, and the experimental diets contained 40% dried buckwheat noodle powder. In experiment 1, rats from CLEA were fed Control (0), Low-rutin (182), Medium-rutin (385), High-rutin (980 mg rutin/100 g) or Catechin (352 mg catechin/100 g) diet for 3 weeks, and in experiment 2, rats from Charles River Laboratories were fed Control or High-rutin diets for 4 weeks. Results indicated that serum total cholesterol level in Medium-and High-rutin groups and the level of free fatty acids in the High-rutin group were significantly lower than that in the Control group (experiment 1). The former result was shown to be reproducible in experiment 2. These results suggested that the rutin in buckwheat noodle has beneficial effects on lipid metabolism.