Development of the cytosolic defence system against microsomal lipid peroxidation in rat liver

Ascorbate-induced lipid peroxidation in rat liver microsomes reaches the adult level in 2-3 days. NADPH-induced peroxidation develops more gradually, in parallel with the activity of NADPH-cytochrome P-450 reductase, attaining adult levels by 10-12 days. The glutathione-dependent cytosolic enzyme activity which inhibits peroxidation is inhibited by bromosulphophthalein. The development of this system lags behind the development of microsomal lipid peroxidation between the ages of 2 and 20 days, allowing peroxidation to proceed.     

Preparation from chitin of (1-4)-2-amino-2-deoxy-beta-D-glucopyranuronan and its 2-sulfoamino analog having blood-anticoagulant properties

Chitosan, prepared by total N-deacetylation of chitin, underwent complete and specific carboxylation at C-6 when oxidized, as the perchlorate salt 2, with chromium trioxide in acetic acid. The resultant (1→4)-2-amino-2-deoxy-β-D-glucopyranuronan, obtained as its perchlorate (3), was N-sulfated with chlorosulfonic acid in pyridine to afford a (1→4)-2-deoxy-2-sulfoamino-β-D-glucopyranuronan, isolated as its amorphous sodium salt 4; the latter displayed moderate blood-anticoagulant activity. The products 3 and 4 showed marked in vitro growth inhibition of leukemia L-1210 cells.     

Endogenous gibberellin levels and senescence in Taraxacum officinale

Summary The level of endogenous gibberellins (GAs) in leaf tissue of Taraxacum officinale was high during leaf growth and expansion but declined progressively during leaf senescence. In the chromatographic system used, most of the GA from Taraxacum leaves moves with the R_f of GA₃. However, several other GAs were also effective in retarding senescence in Taraxacum leaves. It is concluded that ageing of dandelion leaves is associated with a deficiency of endogenous GA.     

Erythrocyte Sensitization by Blood Group-Specific Bacterial Antigens

Human and chicken erythrocytes are readily coated in vitro by blood group active protein-lipopolysaccharides and lipopolysaccharides from E. coli O₈₆ and E. coli O₁₂₈. Serum albumin, α₂- and β-lipoproteins inhibit this sensitization. Blood group B specific agglutination of erythrocytes with B or B-like antigens was obtained with antibodies purified by adsorption on and elution from B erythrocytes. Anti-blood group B and E. coli O₈₆-specific antibodies could be eluted from E. coli O₈₆-coated O erythrocytes. Eel anti-H(O) serum agglutinated O erythrocytes and only those A₁B red cells which were coated with blood group H(O) active E. coli products. Blood group active substances specifically inhibited agglutination of lipopolysaccharide-coated erythrocytes by anti-B and anti-H(O) agglutinins. Demonstrable amounts of lipopolysaccharide could only be removed from coated erythrocytes by washing them at elevated temperatures (58°C) in physiological solutions. Red cell sensitization with B active E. coli O₈₆ substances was achieved in vivo in a minority of severely diseased infants and in germ-free and ordinary chicks which were in tourniquet shock after treatment with cathartics. Therefore, a possible mode by which erythrocytes of patients with severe intestinal disorders acquire antigens is the fixation of bacterial substances to their surfaces, if there are not enough of the normally interfering plasma factors present.     

The Effects of Iron-Mediated Oxidative Stress in Isolated Renal Cortical Brush Border Membrane Vesicles at Normothermic and Hypothermic Temperatures

Experiments on renal cortical brush border membrane vesicles have been undertaken in order to assess the involvement of iron in oxidative stress at physiological temperatures and under conditions of hypothermia. A decrease in temperature stimulated iron-induced lipid peroxidation. The results are discussed in relation to the role of the oxidation state of the iron and iron(II)/iron(III) ratios in the initiation of peroxidative events.