Red blood cell (RBC) fractions were studied after separation of whole blood by means of counterflow centrifugation, Percoll column (Pharmacia, Uppsala, Sweden), and a combination of both separation techniques. Mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and hemoglobin A1c (HbA1c) were measured in each fraction. From the results it was obvious that the combination of both techniques was the best separation technique of these three. MCV had a good correlation with cell age as measured with HbA1c concentration gradient; MCH and MCHC less so. MCV and MCH decreased in parallel to an increase in HbA1c. MCHC increased with increasing HbA1c. From these data it is concluded that there is a steadily ongoing loss of cellular hemoglobin and proportionally more cellular water during the life of the RBC.

Red blood cell (RBC) deformability was determined with an ektacytometer in fractions separated on the basis of differences in cell volume or density. Deformability was measured with ektacytometry (rpm‐scan and osmo‐scan). We studied three groups of RBC fractions: 1. By counterflow centrifugation we obtained fractions of different cell age which showed a slight decrease in mean corpuscular haemoglobin concentration (MCHC) and an increase in surface‐to‐volume (S/V) ratio in fractions with older cells. 2. By Percoll fractionation fractions were obtained which showed a pronounced increase in (MCHC) but no change in S/V ratio. 3. By a combination of both fractionation techniques, fractions were obtained which showed an increased MCHC and an increase in S/V ratio. Deformability in group 1,2 and 3 showed respectively no change, a moderate decrease and a pronounced decrease in fractions of older cells. A decline in deformability occurs during the aging process of the red blood cell. This decline in deformability in old red cells is greater than originally thought. This decline is the result of an increase in haemoglobin concentration and a second factor, probably a decrease in membrane elasticity.

Objective To examine whether a reduced daily glucose load by overnight application of the less-absorbed glucose polymer icodextrin would have favorable effects on lipid profiles of continuous ambulatory peritoneal dialysis (CAPD) patients. Study Design Randomized crossover study with two subsequent periods of 6 weeks. Setting Home PD unit of a secondary-care hospital. Patients Twenty-one nondiabetic CAPD patients (15 male, 6 female; mean age 50.3 ± 11.8 years). Intervention Participants were randomly assigned to receive an overnight dwell with either standard glucose solution or with a 7.5% icodextrin-containing solution. Main Outcome Measures Relation between reduction in the total amount of intraperitoneal infused glucose and parameters of glucose (plasma glucose, insulin, and HbA1C) and lipid metabolism [free fatty acids, plasma lip-ids, lipoproteins, and low density lipoprotein (LDL) sub-fraction profile]. Results After the icodextrin dwells, a reduction of plasma total cholesterol (from 5.43 ± 0.85 to 4.86 ± 0.70 mmol/L, p < 0.001) and LDL cholesterol (from 3.38 ± 0.87 to 2.93 ± 0.73 mmol/L, p = 0.001) was observed. Also, high density lipoprotein (HDL) cholesterol (from 0.95 ± 0.27 to 0.90 ± 0.24 mmol/L, p = 0.029) was reduced, but the plasma total cholesterol-to-HDL ratio remained similar. Plasma free fatty acids and triglyceride levels tended to decrease (from 0.16 ± 0.10 to 0.13 ± 0.08 mmol/L, p = 0.06, and from 2.14 ± 1.96 to 1.92 ± 1.03 mmol/L, respectively). Evaluation of LDL subfraction profiles after ultra-centrifugation showed a more buoyant LDL subfraction profile with fewer dense LDL particles in 6 patients and no changes in 14 patients after icodextrin. The effects on lipids were not accompanied by a decrease in fasting plasma glucose (from 5.76 ± 1.29 to 5.86 ± 0.80 mmol/L) or insulin levels (from 19.5 ± 14.4 to 20.3 ± 13.0 mU/L). Conclusion These results suggest a beneficial effect on lipid profiles of CAPD patients with the use of an overnight dwell with icodextrin.

Previous studies have shown that a considerable amount of haemoglobin is lost from the intact red cell during its lifespan. The aim of this study was to determine the relative contribution of all the haemoglobin components to this process. Therefore, the relative amount of haemoglobins A0, A2, F and the glycated haemoglobins were determined in 24 fractions of different cell age. These fractions were obtained by the combination of counterflow and density centrifugation. When the absolute amount of all haemoglobin components were calculated using the MCH‐values of each fraction, it appeared that the mean red cell loss of haemoglobins A0, A2, F, an unknown X and “rest” comprised, respectively, 440, 23, 1, 4 and 1 amol per cell, while the mean gain of the glycated haemoglobins was 84 amol per cell. This resulted in a net loss of 385 amol of haemoglobin per cell. One of the glycated haemoglobins (HbA1e2) turned out to be the product of further carbamylation. It was concluded that in the first half of the red cell lifespan HbA0 and HbA2 decreased by glycation and carbamylation and that in the second half some of the HbA0 and HbA2 but also some of the glycated and carbamylated haemoglobin components leave the red cell. The total loss amounted to about 20%.

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