Effects of low-dose EPA-E on glycemic control, lipid profile, lipoprotein(a), platelet aggregation, viscosity, and platelet and vessel wall interaction in NIDDM.

OBJECTIVE: To assess the effects of low-dose eicosapentaenoic acid-ethyl-ester on diabetes regulation, lipid metabolism, blood rheology, and platelet reactivity. RESEARCH DESIGN AND METHODS: In a double-blind, randomized, placebo-controlled study, 24 NIDDM subjects received 1800 mg of EPA-E, 900 mg of EPA-E, or a placebo (1656 mg olive oil) daily for 8 wk. RESULTS: The EPA:arachidonic acid plasma ratio increased over an 8-wk period, then declined after a 4-wk wash-out period in the fish-oil groups in a dose-dependent way. Platelet-activating factor-induced platelet aggregation decreased from 75 +/- 7% at wk 0 to 35 +/- 21% at wk 8 in the 900-mg group (P = 0.016) and from 72 +/- 11 to 40 +/- 30% in the 1800-mg group (P = 0.039), but did not change in the placebo group. No effects on ADP- or collagen-induced aggregation could be attributed to EPA-E. In the 1800-mg group low-density-lipoprotein cholesterol increased significantly, without concomitant rise in apolipoprotein B. Triglycerides, glycemic control, lipoprotein (a), blood and plasma viscosity, erythrocyte deformability, and platelet adhesion to and aggregate formation on extracellular endothelial cell matrix were not significantly influenced. CONCLUSIONS: Purified EPA-E in doses of 900 and 1800 mg reduces Platelet-activating factor-induced platelet aggregation without negatively affecting glycemic control. Low-density-lipoprotein cholesterol was elevated in the 1800-mg group.

Power density and exposure time of He-Ne laser irradiation are more important than total energy dose in photo-biomodulation of human fibroblasts in vitro.

The absorption spectrum of human fibroblast monolayers showed several absorption peaks, among them one at a wave-length of 630 nm. Cultures of these fibroblasts were subjected to He-Ne laser (632.8 nm) irradiation of various energy doses by varying power density and exposure time. On three consecutive days the cell monolayers were irradiated for periods between 0.5 and 10 min. Laser power varied from 0.55 to 5.98 mW. Both cell number and collagen type I production were determined for each irradiation condition within one experiment. Results show that laser power below 2.91 mW could enhance cell proliferation (as determined by cell counting), whereas higher laser power (5.98 mW) had no effect. Stimulatory effects were most pronounced at irradiation times between 0.5 and 2 min. Collagen type I production (as determined by an ELISA) was affected in the opposite direction to cell proliferation: when the cell proliferation was increased, collagen type I production was decreased. From these experiments it is clear that exposure time and power density determine the effects of laser irradiation. Both stimulation and inhibition of the observed cell properties can be obtained with the same laser on the same cells.

He-Ne laser irradiation affects proliferation of cultured rat Schwann cells in a dose-dependent manner.

Schwann cell proliferation is considered an essential part of Wallerian degeneration after nerve damage. Laminin, an important component of the extracellular matrix and produced by Schwann cells, provides a preferred substrate for outgrowing axons. To study whether low energy (He-Ne) laser irradiation may exert a positive effect on nerve regeneration through an effect on Schwann cells, its effect was evaluated in vivo. Schwann cells were isolated from sciatic nerves of 4-5-day-old Wistar rates and cultured on 96-multiwell plates. The cells were irradiated by a He-Ne laser beam (632.8 nm, 5.98 mW) that was optically expanded to a beam width of 4 mm. During irradiation the plate was kept in an air-tight box equilibrated with humidified air containing 5% CO2 and kept at 37 degrees C. At three consecutive days, starting either at day 5 or day 8, cells were irradiated each day for 0.5, 1, 2, 5 or 10 min. Both cell number and laminin production were determined for each irradiation condition (n = 5) within one experiment. Schwann cells that were irradiated from day 8 on were hardly affected by laser irradiation. However, the proliferation of cells that were irradiated starting on day 5 was significantly increased after 1, 2, and 5 min of daily irradiation, compared to non-irradiated control cultures. The laminin production per cell of these Schwann cells was not significantly altered. From these results we conclude that He-Ne laser irradiation can modulate proliferation of rat Schwann cells in vitro in a dose-dependent manner.

Effects of flow pulsatility on platelet adhesion to subendothelium.

Platelet adhesion in the annular perfusion system developed by Baumgartner was studied under pulsatile, oscillatory, or steady flow conditions. To investigate in what way pulsatile flow affects platelet adhesion, we developed a flow system that produces a sinusoidal laminar flow superimposed on a constant component in the annular perfusion chamber. Frequencies and amplitudes of this sinusoidal flow were in the physiological range. Pulse frequencies varied between 30 and 120 beats/minute, and different amplitudes of the wall shear rate in the range 75 to 1000 s-1 were studied. Shear rates resulting from the constant flow component were between 500 s-1 and 1800 s-1. Under these conditions, no significant differences in platelet adhesion were observed between steady flow and pulsatile flow. In the case of an oscillatory flow (absence of constant component), a clear dependence of platelet adhesion on the amplitude of the pulse was seen. These data indicate that platelet adhesion in larger blood vessels, such as the aorta and larger arteries where backflow is limited, is not essentially influenced by the pulsatility in these vessels.

Platelet adhesion to multimeric and dimeric von Willebrand factor and to collagen type III preincubated with von Willebrand factor.

As part of a systematic study of platelet interaction with adhesive proteins under flow conditions, we studied platelet adhesion to multimeric and dimeric von Willebrand factor (vWF) coated to glass. vWF-dependent adhesion to collagen type III was studied for comparison. Adhesion to glass-coated vWF and vWF-mediated adhesion to collagen type III were in many respects similar. Both showed no decrease at increasing shear rates and a decline to 50% of maximum with a low-molecular-weight multimeric fraction. Adhesion to glass-coated vWF was partially inhibited by heparin and completely inhibited by prostaglandin I(2) and anti-glycoprotein (GP) Ib and anti-GPIIb-IIIa antibodies. vWF-dependent adhesion to collagen was not inhibited by heparin, was partially inhibited by anti-GPIIb-IIIa, and was completely inhibited by prostaglandin I(2) and anti-GPIb. Recombinant dimeric vWF was made by deletion of the propeptide and expression in Chinese hamster ovary cells. Adhesion was 50% of that with plasma vWF, and larger concentrations of dimeric vWF were required. Adhesion to dimeric vWF was optimal at 1500 s(-1), with a gradual decrease at higher shear rates. We conclude that adhesion to collagen type III is strongly but not completely determined by the adhesive properties of vWF.