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Biomedical subjects

Masahito Imaizumi

Publications and source records attributed to Masahito Imaizumi.

6 recordsLinked to original sources
PubMed2006

Elevation of monocyte-derived microparticles in patients with diabetic retinopathy.

Diabetic retinopathy is associated with microvascular damage and capillary occlusions which are common features of the microangiopathy in diabetes. Monocyte-derived microparticles (MDMPs) are released from activated monocytes and enhance the procoagulant activity, and also activate adhesion reactions. These are key events in the development of capillary occlusion. The MDMPs level in the blood, and platelet activation markers (platelet-derived microparticles (PDMPs), CD62P and CD63) were measured by flow cytometry in 72 diabetic patients. The plasma levels of intracellular adhesion molecule-1 (ICAM-1) and P-selectin were analyzed by ELISA. The level of MDMPs was significantly correlated with the levels of PDMPs (r=0.52, P<0.001), CD62P (r=0.37, P=0.001), CD63 (r=0.31 and P=0.007), P-selectin (r=0.38, P=0.001), and ICAM-1 (r=0.31, P=0.009). The MDMPs level increased with the progression of the diabetic retinopathy: 81+/-14/10(4)platelets (plts) in patients without retinopathy (n=10); 88+/-8/10(4)plts with mild or moderate non-proliferative diabetic retinopathy (NPDR, n=12); 95+/-8/10(4)plts with severe NPDR (n=24); and 112+/-9/10(4)plts with proliferative diabetic retinopathy (PDR) (n=26). The MDMPs level in patients with areas of capillary occlusion (123+/-10/10(4)plts, n=25) was significantly higher than that in patients without areas of capillary occlusion (84+/-5/10(4)plts, n=25; P=0.0008). These correlations suggest that increased levels of MDMPs may accelerate the progression of diabetic retinopathy.

Adult↗
PubMed2005

Low levels of pigment epithelium-derived factor in highly myopic eyes with chorioretinal atrophy.

PURPOSE: To determine the concentration of pigment epithelium-derived factor (PEDF) in the aqueous humor of highly myopic eyes. DESIGN: Observational case series. METHODS: The PEDF concentration in the aqueous humor of 23 eyes of 17 patients with high myopia (axial length >26 mm) who underwent cataract surgery was measured by enzyme-linked immunosorbent assay. RESULTS: The mean concentration of PEDF in eyes with high myopia (0.54 +/- 0.12 microg/ml) was significantly lower than that in control eyes (0.86 +/- 0.04 microg/ml, P = .0022). The PEDF level in myopic eyes with chorioretinal atrophy (0.32 +/- 0.05 microg/ml) was lower than that in myopic eyes without chorioretinal atrophy (0.71 +/- 0.12 microg/ml; P = .041) and control eyes (P = .0003). CONCLUSIONS: The significantly lower concentration of PEDF in eyes with chorioretinal atrophy-associated high myopia probably resulted from degeneration of the retinal pigment epithelial cells and/or the retinal ganglion cells that are the main sources of PEDF in the eye.

Aged↗
PubMed2004

Increased levels of platelet-derived microparticles in patients with diabetic retinopathy.

Diabetic retinopathy is caused by capillary occlusions. Platelet-derived microparticles (PMPs) stimulate the coagulation cascade and increase leukocyte and endothelial cell adhesions, both of which are key events in the development of diabetic retinopathy. However, the correlation between the levels of PMPs and diabetic retinopathy has not been precisely determined. The PMPs levels and the expression of platelet CD62P and CD63 were measured in 92 diabetic patients. The level of PMPs was significantly correlated with the expression of CD62P (r = 0.76, P < 0.0001) and CD63 (r = 0.71, P < 0.0001). The mean level of PMPs in diabetics (507+/-15/10(4) platelets (plt), mean+/-S.E.) was significantly higher than that in normal. The PMPs levels increased with the progression of the diabetic retinopathy; 480+/-28/10(4) plt in diabetic patients without retinopathy (n = 25), 504+/-40/10(4) plt with mild or moderate non-proliferative diabetic retinopathy (n = 13), 512+/-29/10(4) plt with severe non-proliferative diabetic retinopathy (n = 25), and 528+/-25/10(4) plt with proliferative diabetic retinopathy (n=29). The PMPs level in patients with non-perfused retinal areas (582+/-27/10(4) plt, n = 24) was significantly higher than patients without non-perfused areas (469+/-23/10(4) plt, n = 30; P = 0.0096) and without diabetic retinopathy (P = 0.024). These high correlations indicate that increased levels of PMPs may accelerate diabetic retinopathy.

Adult↗
PubMed2004

Decrease of pigment epithelium-derived factor in aqueous humor with increasing age.

PURPOSE: To determine whether the level of pigment epithelium-derived factor (PEDF) in the aqueous humor is altered with age. DESIGN: Observational case series. METHODS: The PEDF concentration in the aqueous humor was measured by enzyme-linked immunosorbent assay in 152 eyes of 121 patients who underwent cataract surgery. RESULTS: The mean aqueous level of PEDF was 0.86 +/- 0.04 microg/ml (mean +/- standard error, 70.7 +/- 1.0 years). The PEDF levels decreased with increasing age, and the decrease was significantly correlated with age (Pearson product moment correlation coefficient, r = - 0.22, P =.006). The mean PEDF level in the men (0.76 +/- 0.06 microg/ml, 53 eyes, 71.5 +/- 2.0 years) was significantly lower than that in women (0.91 +/- 0.04 microg/ml, 99 eyes, 70.2 +/- 1.1 year, P =.03). CONCLUSIONS: The negative correlation of PEDF level and age should be considered in age-related eye diseases, especially those associated with angiogenesis.

Adolescent↗
PubMed2004

Decreased levels of pigment epithelium-derived factor in eyes with neuroretinal dystrophic diseases.

PURPOSE: To determine the concentration of pigment epithelium-derived factor (PEDF) in the aqueous humor of eyes with neuroretinal dystrophy. DESIGN: Observational case series. METHODS: Aqueous humor was obtained from patients during cataract surgery, and the PEDF concentration in the aqueous humor was measured by enzyme-linked immunosorbent assay. The primary diagnosis was cataract in 162 eyes; of these there were five eyes with retinitis pigmentosa, nine eyes with advanced glaucoma, and 148 eyes with cataract alone. RESULTS: The mean levels of PEDF in eyes with retinitis pigmentosa (0.24 +/- 0.04 microg/ml, mean +/- SE, P =.0004) and advanced glaucoma (0.46 +/- 0.08 microg/ml, P =.003) were significantly lower than that in eyes with cataract alone (0.86 +/- 0.04 microg/ml). CONCLUSION: The lower levels of PEDF in eyes with neuroretinal dystrophy may be related to the loss of the retinal ganglion cells or retinal pigment epithelium cells that synthesize PEDF.

Aged↗