Immunosuppressive effects of barbituric acid derivatives. II. Effect of 1.3-bis(piperidinomethyl)-5-ethyl-5-phenyl-barbituric acid on humoral and cell-mediated immunity in mice

Astrocyte swelling in hepatic encephalopathy: molecular perspective of cytotoxic edema

Hepatic encephalopathy (HE) may occur in patients with liver failure. The most critical pathophysiologic mechanism of HE is cerebral edema following systemic hyperammonemia. The dysfunctional liver cannot eliminate circulatory ammonia, so its plasma and brain levels rise sharply. Astrocytes, the only cells that are responsible for ammonia detoxification in the brain, are dynamic cells with unique phenotypic properties that enable them to respond to small changes in their environment. Any pathological changes in astrocytes may cause neurological disturbances such as HE. Astrocyte swelling is the leading cause of cerebral edema, which may cause brain herniation and death by increasing intracranial pressure. Various factors may have a role in astrocyte swelling. However, the exact molecular mechanism of astrocyte swelling is not fully understood. This article discusses the possible mechanisms of astrocyte swelling which related to hyperammonia, including the possible roles of molecules like glutamine, lactate, aquaporin-4 water channel, 18 KDa translocator protein, glial fibrillary acidic protein, alanine, glutathione, toll-like receptor 4, epidermal growth factor receptor, glutamate, and manganese, as well as inflammation, oxidative stress, mitochondrial permeability transition, ATP depletion, and astrocyte senescence. All these agents and factors may be targeted in therapeutic approaches to HE.

Effect of a membrane-stabilizing compound on calcium binding to the plasma membrane of Acanthamoeba castellanii

Binding of calcium ions at the plasma membrane was studied in Acanthamoeba cells pretreated with ZIMET 3164, a benzimidazole nitrogen mustard derivative, which is known to show a potent immunosuppressive action combined with a membrane-stabilizing effect in mice. For reference, 2 compounds were applied: ZIMET 3393 (Cytostasan¿), another benzimidazole mustard derivative, which exerts only a moderate membrane effect and acts as a strong cytostatic, and ZIMET 176/68, a barbituric acid derivative, which acts as an inhibitor of humoral immune responses but without membrane-stabilizing effect. Application of any of the 3 compounds does not reduce the appearance of calcium binding sites, visualized by means of ultracytochemical reaction, notwithstanding their different action in the mammalian organism. On the contrary, it was estimated by morphometric analysis that the number of Ca-dependent deposits was augmented after treatment with low doses of any of the 3 compounds, what seems to be connected with the induced metabolic disturbances in low molecular phosphates level. High doses and/or prolongation of treatment of the cells resulted in diminution of the number of deposits and induces profound disturbances in cell ultrastructure, probably due to the toxic action of the applied doses. In these cases, band-like structures crosslinking the two leaflets of the plasma membrane may be observed; it is suggested that they represent integral membrane proteins.

Therapeutic effect of beta-[1-phenyl-5-bis(beta-chloroethyl)-amino-benzimidazolyl-(2)-DL-alanin (ZIMET 3164) on immune complex nephritis of NZB hybrid mice

Beta-[1-Phenyl-5-bis(beta-chloroethyl)-amino-benzimidazolyl-(2)]-DL-alanin (ZIMET 3164), a highly immunosuppressive but moderately cytostatic agent, was found to be able to prevent the progression of spontaneous murine immune complex nephritis in a dose-dependent fashion. For experiments, BCG-stimulated conventional female (NMRI X NZB)F1 mice suffering from rapidly progressive nephritis, BCG-stimulated and unilaterally nephrectomized (NMRI X NZB)F1 females, and (AB/Jena X NZB)F1 females characterized by a prolonged course of the disease were used. The beneficial effect was quantified by fluorescence photometry and histometry, and semiquantitatively detected by estimation of the extent of damage of individual glomerular structures when histometric methods were unsuited. Treatment of young adult animals characterized by slight to moderate glomerular lesions was more effective than of older ones with advanced nephritis. At equi-immunosuppressive dose levels ZIMET 3164 was about twice as effective as the reference substance cyclophosphamide.

Pathogenicity of Mengo virus to mice. III. Potentiation of infection by immunosuppressants

Mengo virus has been described to cause, in dependence on the virus dose, lethal panencephalomyelitis and exocrine pancreatitis in mice after i.p. inoculation. Two immunosuppressive agents, cyclophosphamide and 1,3-bis(piperidinomethyl)-5-ethyl-5-phenyl-barbituric acid (ZIMET 176/68), were shown to potentiate Mengo virus infection as demonstrated by histopathology and enhanced mortality. Organotropism of Mengo virus did not change under the drug treatment. However, the histological lesions in brain, spinal cord and pancreas failed to exhibit any inflammatory reaction in case of cyclophosphamide, due to its antiphlogistic properties. Considering the mode of action of the drugs employed and the pathogenesis of Mengo virus infection in mice, it is concluded that in the system used both cyclophosphamide and ZIMET 176/68 exert their potentiating effects by interfering with primary virus-macrophage interaction.