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Membrane fluidity of bovine platelets was examined with diphenylhexatriene (DPH), its cationic trimethylammonium derivative (TMA-DPH) and anionic propionic acid derivative (DPH-PA). After addition of these probes to platelet suspensions at 37 degrees C, the fluorescence intensity of DPH-PA reached equilibrium within 2 min, whereas those of DPH and TMA-DPH increased gradually. With increase in the fluorescence intensity of TMA-DPH, its fluorescence anisotropy decreased significantly, but the fluorescence anisotropies of DPH-PA and DPH did not change during incubation. The gradual increase of fluorescence intensity of TMA-DPH was due to its penetration into the cytoplasmic side of the platelet membrane, as shown quantitatively by monitoring decrease in its extractability with albumin. Transbilayer movement of TMA-DPH was markedly temperature-dependent, and was scarcely observed at 15 degrees C. The fluorescence intensity of TMA-DPH was much higher in platelet membranes and vesicles of extracted membrane lipids than the initial intensity in intact platelets. Moreover, the fluorescence anisotropy of TMA-DPH was much lower in the former preparations than the initial value in intact platelets. These results suggest that binding sites for TMA-DPH in the cytoplasmic side of the platelet membrane are more fluid than those in the outer leaflet of the plasma membrane. Platelet activation by ionomycin induced specific change in the fluorescence properties of TMA-DPH without causing transbilayer incorporation of the probe.

Purpose It is unclear whether hypomagnesemia is an independent risk factor or innocent bystander for mortality in maintenance hemodialysis (MHD) patients. Thus, we studied associations between hypomagnesemia and all-cause as well as cardiovascular (CV) mortality in MHD patients. Methods Baseline clinical characteristics and coronary artery calcium score (CACS) of 353 Japanese MHD patients were reviewed. Three-year survival rate and mortality risk factors were assessed. Results Median (interquartile range) age, dialysis vintage, serum magnesium (Mg), serum albumin and CACS of the subjects were 68 (60–78) years, 75 (32–151) months, 2.4 (2.2–2.7) mg/dl, 3.6 (3.3–3.8) g/dl, and 1181 (278–3190), respectively. During the 3-year period, 91 patients died. Kaplan–Meier overall 3-year survival rates were 59.0% in in patients with Mg < 2.4 mg/dl ( n = 136) and 82.3% in patients with Mg ≥ 2.4 mg/dl ( n = 217), ( P < 0.0001). In Cox regression models not incorporating serum albumin, Mg < 2.4 mg/dl was significantly associated with 3-year all-cause death, independent of age, dialysis vintage, average ultrafiltration, Log (CACS + 1), warfarin use, serum potassium, high-sensitivity C-reactive protein (hsCRP), phosphate, uric acid, and intact parathyroid hormone [Hazard ratio (HR) 95% confidence interval (CI): 2.82 (1.31–6.29), P = 0.0078], and CV death, independent of age, dialysis vintage, Log (CACS + 1), warfarin use, serum hsCRP, and uric acid [HR (95% CI): 4.47 (1.45–16.76), P = 0.0086]. Nevertheless, associations of Mg < 2.4 mg/dl with all-cause and CV mortality were all absent in models that included serum albumin. Conclusions Hypomagnesemia is not an independent risk factor for mortality but is associated with malnutrition in MHD patients.

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Objective: This study evaluated associations of serum matrix Gla protein (MGP), plasma vitamin K1, and plasma vitamin K2 with coronary artery calcium score (CACS) and cardiovascular disease (CVD) in maintenance hemodialysis (MHD) patients. Methods: Subjects comprised 112 MHD patients aged 30-60 years and 40 age-matched healthy subjects. Total MGP, vitamin K1, vitamin K2, and lipid profile were examined in all subjects; other clinical data, medication use, and CACS were assessed only in MHD patients. Determinants of MGP in all subjects were identified by regression analysis. Factors associated with CACS and CVD in MHD patients were identified by regression analysis and logistic analysis, respectively. Results: Lower plasma levels of vitamin K1 corrected for triglycerides [0.39 (0.24-0.70) vs. 0.77 (0.48-1.34) ng/mg, p < 0.001], higher frequency of plasma vitamin K2 0.05 ng/ml (p ¼ 0.23), and higher serum total MGP (288.4 ± 44.2 vs. 159.7 ± 40.6 ng/ml, p < 0.0001) were observed in MHD patients than in healthy controls. Total MGP level was significantly associated with levels of vitamin K1 corrected for triglycerides (p <0 .001) and vitamin K2 0.05 ng/ml (p < 0.05) in all subjects. Total MGP level was significantly associated with presence of CVD (p <0 .05), but not CACS, in MHD patients. Conclusion: The end-stage renal disease on hemodialysis is a deficiency state of vitamin K. Total MGP was significantly higher in MHD patients compared to healthy subjects and total MGP was associated with the presence of CVD, but not CACS, in MHD patients.