During hemodialysis, platelets are activated across a dialyzer. Soluble P-selectin (sP-selectin) is a form of P-selectin which is a glycoprotein relocated from secretory granules to the surfaces of platelets and endothelial cells after these cells have been physiologically activated. To investigate whether sP-selectin is useful as a marker of platelet activation during hemodialysis, we measured the plasma concentration of sP-selectin by enzyme-linked immunosorbent assay in 6 patients hemodialyzed in our institute using regenerated cellulose (RC) membranes and thereafter polysulfone membranes. Concomitantly, we also measured the plasma concentration of platelet factor 4 and β-thromboglobulin which are released from α-granules of activated platelets. During hemodialysis with RC membranes, the β-thromboglobulin level was significantly increased 15 min (p < 0.05) and the sP-selectin level 15 (p < 0.05) and 180 min (p < 0.05) after initiation of dialysis on the venous side as compared with the arterial side of the hemodialyzer. During hemodialysis with polysulfone membranes, no significant variation in plasma β-thromboglobulin and sP-selectin levels was detected. The platelet factor 4 level increased more significantly across a dialyzer 180 min after initiation of dialysis with RC than with polysulfone membranes (p < 0.01). The changes in plasma platelet factor 4 and β-thromboglobulin levels demonstrated that platelets are more activated during hemodialysis with RC than with polysulfone membranes. The changes in plasma sP-selectin levels during hemodialysis with RC confirm that the release of P-selectin purely from activated platelets was detected by enzyme-linked immunosorbent assay. sP-selectin may be a marker of platelet activation during hemodialysis.

Serum leptin concentrations in normal humans have been reported to correlate with the body mass index (BMI) as well as with the body fat mass. In this study, we measured serum leptin concentrations in 107 patients on hemodialysis, 30 of whom had diabetes mellitus as the cause, and examined the clinical significance. Furthermore, we evaluated the effects of high-flux dialysis membranes on serum leptin levels. Serum leptin concentrations had a linear correlation with BMI as well as with the percentage of body fat in patients on hemodialysis. The serum leptin concentrations showed a positive correlation with the serum concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglyceride, the body weight, the BMI, and the percentage of body fat. The serum leptin levels were not different between the diabetic and the nondiabetic groups. The serum leptin levels in the nondiabetic group were nearly fourfold higher in women than in men. We investigated the differences in the rate of reduction in serum leptin after dialysis with polysulfone membrane dialyzers (PS-N and PS-UW) in comparison with a cellulose membrane dialyzer (AM-SD), and as a result, we found that the polysulfone membrane dialyzers removed serum leptin, while the cellulose membrane dialyzer did not. We conclude that in patients on hemodialysis, the serum leptin concentration is a valuable clinical marker of the body fat content and may also contribute to the evaluation of hyperlipidemia.

No abstract

Methoxy polyethylene glycol-epoetin beta, a continuous erythropoietin receptor activator (CERA), is reported to be effective in managing renal anemia but there is little data about CERA in Japan. This study aimed to ascertain the effects of CERA in Japanese hemodialysis patients and the appropriate starting dose of CERA when switching from other erythropoiesis-stimulating agents. We switched 61 stable hemodialysis patients to 4-weekly intravenous CERA, from either epoetin beta (rHuEPO) or darbepoetin alpha (DA). When determining the initial dose of CERA, we used guidelines recommended by the Japanese supplier for switching from rHuEPO, but for DA we based the CERA dose on European reports, because no Japanese guidelines exist. Fifty-two patients completed the 28-week study. Hemoglobin was maintained within the target range (10.0-12.0 g/dL). The required CERA dose decreased over the 28 weeks. The hemoglobin level and CERA dose stabilized faster when switching from DA. CERA showed similar efficacy in diabetic and non-diabetic patients. The effect of CERA is similar regardless of whether patients switch from low-or high-dose erythropoiesis-stimulating agents. In conclusion, CERA is effective for Japanese hemodialysis patients at a lower dose than expected.

Background. The parameters of the urea kinetic model (UKM) [product of dialyzer urea clearance and treatment time divided by body urea volume (Kt/V), protein catabolic rate (PCR), percent creatinine generation rate (%CGR)] are predictors of prognosis in patients on hemodialysis. In addition, adequate nutritional status has been recently recognized to be important for patient survival. We examined the relationship between serum amino acid levels and the parameters of the UKM, and investigated whether they could be predictors of patients' prognosis. Method. We studied 56 non-diabetic patients undergoing hemodialysis, and compared them with 101 normal controls. Serum amino acid levels were measured by highperformance liquid chromatography. Kt/V, PCR, and %CGR were calculated by Shinzato's method. Results. The serum amino acid patterns of patients on hemodialysis were characterized by low essential amino acid levels and high non-essential amino acid levels. Kt/V did not correlate with any amino acid levels. PCR correlated positively with urea and 3-methylhistidine, and negatively with aspartic acid and glutamic acid. %CGR correlated positively with serine, and negatively with glutamic acid. There were no correlations between valine/ glycine and PCR, both of which are indicators of protein intake. Conclusions. We considered that serum amino acid levels are poor predictors of patients' prognosis. Of the various causes of alterations in serum amino acid levels, renal metabolic dysfunction and protein-calorie malnutrition appear to be important.Key words Amino acid · Nutritional status · Chronic renal failure · Hemodialysis · Urea kinetic model · Kt/V · Protein catabolic rate (PCR) · Percent creatinine generation rate (% CGR)