Oxidation of lipids and membranes I: In vitro formation of peroxidative lipid polymers

Fluorescent polymers were obtained by oxidizing partly emulsified linolenic acid with different oxidants. The speed of formation of polymers differed for the various oxidants, and the difference was not a simple function of the oxidation potential. The speed of polymerization also depended on the nature of the emulsion. The presence of egg albumen in the emulsion enhanced polymer formation with all oxidants. When the oxidants used are arranged in the order of decreasing speed of polymer formation, the order is different in the presence of albumen from what it is in the absence of albumen. With different oxidation catalysts most antioxidants and amino acids tested enhanced polymerization. In oxidation with ferric ions, with K-dichromate, and without added oxidants the only antioxidants which delayed polymerization were “inhibitors”. “Retarders” enhanced polymerization. With KMnO₄ slight delay was caused by some retarders. The findings indicate that not only oxidation catalysts, but also proteins, amino acids, and antioxidants enhance polymerization. The possibility is suggested that in animal cells lipid pigment formation might represent a mechanism for neutralizing free radicals.     

Conservation of Glycerolated Cultures of Ochromonas danica and O. malhamensis at −10 C

SYNOPSIS. Ochromonas danica in a complex natural growth medium dies at 6–10 C in 4 days; O. malhamensis in ∼2 days. O. danica grown in the medium supplemented with 4.0% glycerol survived at −10±2 C for 35 days, and with 8% glycerol 29 days. O. malhamensis lasted only to 5 days in these media supplemented with 4% glycerol. Ethylene glycol and dimethylsulfoxide were too toxic to be effective. Difficulties in freeze-preservation of certain other phagocytic cells, notably blood granulocytes having comparatively simple flexuous outer membranes, add interest to use of O. danica and O. malhamensis as test organisms for preservation methods, especially in the convenient, inexpensive -10 to -20 C range. Biphasic media with an overlay of distilled water serve for conservation at room temperature. Problems of mutational erosion of these photosynthetic phagotrophs are discussed.     

Histochemical study on the pathogenesis of chlorocyclizine-induced pulmonary lipidosis.

Male rats were fed a diet containing chlorocyclizine in high concentrations for about 3 weeks. They lost weight and showed respiratory distress. The lungs contained clusters of foam cells in the alveoli. Acid esterase staining revealed reduction of activity in alveolar cells presumed to be granular pneumocytes and absence of activity in the foam cells. The lipid showed in the foam cells could not be stained with Sudan dyes, except at high temperature, and was not stained by phospholipid and cholesterol procedures. This indicated that the stored lipids are probably solid at room temperature, consisting of saturated triglycerides and/or phospholipids. It is suggested that the lipid originated in the granular pneumocytes. The drug might have deranged the esterase-phospholipase activity in these cells and in the macrophages.     

The Effect of Formaldehyde on Tissue Lipids and on Histochemical Reactions for Carbonyl Groups

Histcchemical and chemical evidence indicates that formaldehyde combines with unsaturated lipids at the double bond. The resulting complex contains a free carbonyl group which probably originates from the formaldehyde. The reaction occurs over a wide pH range, and takes place in the absence of oxygen or moisture. The reaction product is visualized by the Schiff reagent, and by the Ashbel-Seligman procedure. In the plasmal procedure, when performed on formalin-treated material, the reaction has the same significance as the pseudo-plasmal reaction, i.e. it denotes the presence of double bonds. The Ashbel-Seligman technic seems to be more sensitive to this complex than the Schiff reagent and shows it more markedly than it does the true plasmals and the atmospherically oxidized unsaturated compounds.     

Different modes of cell death and related phenomena: a proposal for a meaningful terminology in relation to tests of lethality

The terms death (as an irreversible occurrence), necrosis and apoptosis are well defined and generally accepted in cell biology. Procedures and terminology related to estimation of different forms of cell mortality are, however, less clear and exact. Evaluation of the rate of mortality is important for numerous biological processes such as growth, atrophy, regeneration and neoplasia. Procedures used for assessing cell mortality include: 1. dye exclusion tests which were shown to be inadequate in apoptosis; 2. release of radioactive markers, also inadequate, as they occur also in life during shedding of membranes and cleavage of cell parts; 3. morphological and histochemical procedures which show only relatively late changes (autolysis) in cells which have not yet been completely obliterated; 4. absence of synthetic activities, which do not necessarily indicate death (e.g. mature erythrocytes); 5. colony forming capacity in cultures, which are considered by most authors as the most useful tests for assessing the effects of cytotoxic treatments. These tests do not, however, assess viability, but rather reproductive capacity. In all these tests, delayed changes in vitality can be determined by repeated or continuous testing. The following new terms are proposed and related to presently available tests. Aposchisis--for cleavage of cell parts not necessarily associated with cell death. N-mortality--for necrosis type of mortality estimated by the dye exclusion tests. A-mortality--for apoptosis type of mortality, which cannot be directly estimated at present. Acarpy--for loss of reproductive capacity of cells which is assessed by the colony forming tests.