Content of reticulocyte hemoglobin is a reliable tool for determining iron deficiency in dialysis patients.

BACKGROUND: The evaluation of iron status in dialysis patients provides information essential to the planning of adequate recombinant human erythropoietin (rHuEPO) treatment. Iron status of the patients can be determined from the recently available measurement of content of reticulocyte hemoglobin (CHr). METHODS: In this study, to clarify the accuracy of CHr in diagnosing iron deficiency in hemodialysis (HD) patients, we initially compared CHr with such conventional iron parameters as serum ferritin levels, transferrin saturation and serum soluble transferrin receptor levels. Secondly, we investigated the changes in CHr during iron supplementation for iron-deficient patients to determine whether this marker is a prospective and reliable indicator of iron sufficiency. The participants in this study were 149 hemodialysis (HD) patients and 53 age-matched healthy subjects. Iron deficiency was defined as having a TSAT of less than 20% and serum ferritin of less than 100 ng/ml. Conventional parameters of red blood cells and CHr were measured by an ADVIA120 autoanalyzer. RESULTS: Mean CHr was 32.3 +/- 2.2 pg in the patients undergoing hemodialysis treatment. CHr significantly correlated with iron parameters in the dialysis patients. Logistic regression analysis was performed to determine the relationship between CHr and each outcome measure, and CHr was the significant multivariate predictor of iron deficiency. Iron supplements given to the patients with low CHr and hematocrit (Hct) significantly increased Hct, resulting in a decrease in the weekly dosage of rHuEPO. CONCLUSIONS: CHr, measured simultaneously with Hct, is a sensitive and specific marker of iron status in dialysis patients.

Molecular cloning of rat p38 mitogen-activated protein kinase and it's osmotic regulation in rat kidney.

Rat p38 mitogen-activated protein (MAP) kinase cDNA was isolated from rat kidney cDNA library using a PCR cloning strategy. The deduced amino acid sequence consists of 360 amino acids and shares 95.3% similarity with human p38 MAP kinase. The message for rat p38 MAP kinase was about 3.4 kilobases and was highly expressed in the kidney. In water-deprived rat kidneys, the steady-state levels of p38 MAP kinase mRNA increased about 2.7-fold as compared with those of control rats. This result suggests that p38 MAP kinase may play an important role in the osmoregulation in the kidney.

Characterization of the glomerular endothelial cell in culture.

Because of difficulties associated with the culture, cloning and propagation of glomerular endothelial cells (GENs), the biological properties of these cells remain largely unknown. We modified the methods established by Ballermann to propagate GENs from adult bovine kidney. We found that the addition of insulin, transferrin and selenium into the standard culture media was an important step in promoting the propagation of the first clone from a single cell and in maintaining the viability of the cells. These cells expressed factor VIII-related antigen and took up acetylated-LDL, but did not contain the Weibel-Palade body, unlike endothelial cells derived from large vessels. Furthermore, GENs were compared with aortic endothelial cells (AECs) to investigate the differences in culture conditions. Compared with AECs, GENs required a higher concentration of serum and the supplementation of growth factor to maintain their biological activity. In addition, GENs were very susceptible to trypsinization and produced prostaglandin E2 as a major cyclooxygenase product, whereas AECs produced PGI2. These findings suggest that GENs will be easily obtained from adult bovine kidney in culture and provide useful information on the functional properties of these cells under physiological and pathophysiological conditions.