The effects of hemodialysis with different membranes on middle molecules and uremic neuropathy.

Twenty-four hemodialysis patients, 14 with uremic neuropathy and 10 symptom-free, were studied over 12 months. Cuprophan and AN 69 membrane dialyzers were used in their treatment in order to investigate the influence of different membranes on plasma levels of middle molecular weight substances (MMS) and uremic neuropathy. Hemodialysis with the cuprophan membrane caused no significant changes in plasma MMS levels or in the neurological condition of patients. The effect of dialysis with AN 69 membrane depended on initial plasma MMS levels. Initially high plasma MMS levels decreased significantly and significant improvement of neuropathy was achieved. In neuropathic patients with plasma MMS levels similar to those of symptom-free patients, hemodialysis with AN 69 membrane had no effect. These results suggest that hemodialysis with MMS high-permeability membranes may be recommended for neuropathic patients with high plasma MMS levels.

Cellular distribution of protein-disulfide interchange enzyme activity in mouse spleen.

In an attempt to precise the cellular distribution of protein-disulfide interchange enzyme activity within different compartments of the splenic lymphoid tissue, we have analyzed the protein-disulfide interchange (PDI) enzyme activity in adherent and nonadherent cell populations of normal and T-cell depleted CBA mice. In vivo depletion of T-cells, as evaluated by functional and cytotoxic tests, was achieved by two i. v. injections of anti-T monoclonal antibodies (Mab F7D5). Nonadherent cell populations were found to have levels of protein-disulfide interchange enzyme activity significantly higher than that of the adherent cells. Pretreatment with F7D5 monoclonal antibodies enhanced the protein-disulfide interchange activity in nonadherent cell population, thus indicating that the major source of the enzyme activity are nonadherent spleen cells, which do not bear T-cell marker, probably B-cells.

The ontogenetic evolution of acidic phosphoprotein phosphatase activity in the lymphatic tissue and the liver of the rat.

We have shown that an acidic phosphoprotein phosphatase (APP-ase) has a different pattern of postnatal maturation in the spleen, thymus and liver of rats and mice. The APP-ase activity increases during the first eight months of postnatal life in the spleen of rats (when it attains an 8--10 times higher value than at birth) and up to the sixth month of life in the spleen of mice. It increases considerably during the first two weeks of postnatal life in the thymus of rats and mice; in the liver of rats it reaches maximum activity before birth, but continues to increase up to the sixth month of postnatal life in the liver of mice. The results show also that the APP-ase from the spleen, thymus and liver of rats is equally active in dephosphorylating ATP and phenyl phosphate during the whole life span of rats, but not in relation to beta-glycerol phosphate. After analyzing its substrate specificity, its pH dependence in relation to different substrates, its kinetic properties, as well as its behaviour towards ascorbic acid and different inhibitors (sodium tungstate and sodium molybdate, L-tartrate, L-phenylalanine and L-cysteine) we have come to the conclusion that the rat spleen APP-ase is different from "nonspecific" acid and alkaline phosphatases and very similar to the EC 3.1.3.16 acid phosphoprotein phosphatase.