Influence of middle molecules on the anemia of uremic patients.

To evaluate their toxicity at the cellular level, middle molecules from uremic serum were incubated with erythrocytes from healthy subjects and the activity of the enzyme Delta-aminolevulinic acid dehydrase (D-ALA-D) and peroxidative hemolysis were investigated. Uremic middle molecules caused a significant decrease of the D-ALA-D activity of normal erythrocytes which was not due to differences in the concentrations of Pb, Cd or Zn. The decreased enzyme activity could be restored by adding reduced glutathione (GSH; 5 mmol/L) together with the middle molecules to the assay system. Uremic middle molecules caused a significant increase of peroxidative hemolysis in normal erythrocytes. Uremic middle molecules contribute to the anemia of uremic patients by impeding hemoglobin synthesis and by increasing peroxidative hemolysis, possibly by affecting SH-groups. H2O2-producing compounds should be avoided in uremic patients.

Hemodiafiltration: a new alternative to hemofiltration and conventional hemodialysis.

A new dialysis method, termed hemodiafiltration, is proposed. The procedure consists of the combination of hemofiltration and conventional hemodialysis using high flux membranes with a transmembrane pressure (TMP) of 300--500 mmHg and a dialysate flow of 900 ml/min. Due to the combination of convective mass transfer and diffusion, the clearance values of both small and larger molecules are significantly higher than during hemofiltration or hemodialysis alone with the same membranes. The removal of excess water is better tolerated than during hemodialysis. With this new method, six patients have been successfully treated for six months (three times per week, three hours per treatment) without side effects. Thus hemodiafiltration appears to be the method of choice to shorten dialysis time.

Simultaneous hemofiltration/hemodialysis: an effective alternative to hemofiltration and conventional hemodialysis in the treatment of uremic patients.

Hemofiltration and hemodialysis were performed simultaneously with the Polyacrylnitrile membrane in a single pass dialyzate flow system. Due to the combination of convective mass transfer and diffusion, the clearances of both small and large molecules were significantly higher than during hemofiltration or hemodialysis alone. The removal of excess water was better tolerated than during hemodialysis. Six patients have been treated by this technique for 6 months 3 X 3 hr/week without side effects, and the new procedure appears to be the method of choice to shorten dialysis time.

[Possibilities and limitations of immunosuppressive therapy for glomerulonephritis]. / Möglichkeiten und Grenzen immunsuppressiver Therapie der Glomerulonephritis.

Possibility and necessity of the immunosuppressive treatment is considerably determined by the underlying pathologo-anatomical substrate. The uncertainty concerning the chances of the success of such a therapy for the individual patient at least still at present allows a latitude of estimation. From this results the demand for a particularly intensive conscience of the responsibility taken on by us in finding the decision.

Globin synthesis in uraemia.

Globin synthesis was measured by incubating washed packed red cells with a balanced amino acid mixture and 14C-Histidine. After globin had been isolated from the haemolysate the 14C-incorporation rate per 10 mg globin per min was estimated. With regard to globin synthesis no differences existed between patients on chronic intermittent haemodialysis therapy (n equals 41), patitents suffering from secondary anaemia due to chronic infection, rheumatism or malignant diseases (n equals 21) and healthy subjects (n equals 37). Patients with acute bleeding on the other hand, had significant higher 14C-incorporation rates caused by an increase of the reticulocyte count mu1 blood (n equals 13). When substances retained in renal failure were added to the incubation mixture a marked inhibition took place with guanidinosuccinic acid, methylguanidine and fraction containing peptides with a molecular weight between 1200-1400 present in uraemic serum and normal urine, but not in serum from patients without renal failure.