The lipid composition of plasma membrane and mitochondrial fractions from epididymal adipocytes of cold-acclimated rats.

1. The effects of cold acclimation (5 degrees C) on the lipid composition of plasma membrane and mitochondrial fractions from epididymal adipocytes of rats were studied. 2. The adipocyte plasma membrane fraction of the cold-acclimated rats had lower lipid, phospholipid and cholesterol to protein weight ratios, a lower cholesterol to sphingomyelin molar ratio, and a higher linoleic acid content in the phospholipids than controls. 3. The mitochondrial fraction of the cold-acclimated rat adipocyte had lower ratios of cholesterol to protein (weight), to phospholipid and to cardiolipin (molar), and less sphingomyelin content than did controls. 4. These data, discussed in terms of alterations in physical and biochemical properties, indicate cold-induced changes at the membrane level in rat epididymal adipocytes.     

Biological effect of lipid fractions of Actinomycetes

Biological activity of lipid fractions of actinomycetes was examined on microorganisms and laboratory animals. The anabolic effect of the acetone fraction of Actinomyces aurigineus 2377 (on Wistar female rats), anabolic effect of sterols of Actinomyces griseus 15 (on chicks), and the high growth stimulating effect (up to 40-60%) of sterols of Actinomyces canosus 89 (on rats) were noted. The estrogenic effect of sterols of Act. griseus 15, Act. griseus 20 and Act. albodenitrificans 13a on the sex system was shown. The antimicrobial properties of lipid fractions differed in their selectivity with respect to the test organisms and depended also on the actinomycete species and cultivation conditions.     

Comparability of delayed hypersensitivity in various rodents. I. Regulatory mechanism of delayed footpad reactions in the hamster

A relationship between delayed footpad reaction and antibody production was observed in hamsters immunized with erythrocytes of the mouse (MRC), sheep (SRC), or chicken (CRC). (i) In hamsters immunized with MRC in incomplete Freund's adjuvant (IFA), delayed reactions were positive in spite of high titers of IgM. Delayed reactions became negative with the appearance of IgG in hamsters pretreated with mouse spleen cells. (ii) In those immunized with SRC in IFA, positive delayed reactions were elicited only in the absence of IgG. Delayed reactions were converted from negative to positive by treatment with cyclophosphamide before elicitation in the presence of IgG. (iii) After immunization with SRC in complete Freund's adjuvant (CFA) or CRC in IFA or CFA, positive delayed reactions were elicited in the presence of IgG. There may exist an unstable form of delayed footpad reactions, which is regulated by antibody production, and a stable form, which is not regulated. Suppression in the former may be ascribed to some mechanism which is sensitive to cyclophosphamide and may be related to the production of IgG but not IgM.     

Allergic reactions of pulsating cardiac cells in culture

The authors describe a method of cultivation and growth peculiarities in a culture of beating cells of the human embryo heart. The influence of homologous anticardiac antibodies and of the ambrosia allergen antiambrosia antibody complex on the contracting cells of the heart of chick and duck embryos was studied in a culture. Pulsation of the cardiac cells was delayed and weakened under the effect of these factors; their vacuolization developed.     

Effect of ferritin-containing fractions with different iron loading on lipid peroxidation.

Ferritin-containing fractions with different degrees of iron loading were prepared. All ferritin fractions stimulated the peroxidation of bovine brain phospholipid liposomes, as measured by the formation of thiobarbituric acid-reactive material. This stimulation was increased in the presence of ascorbate. Iron salts of equivalent concentration to those of the ferritin fractions were more stimulatory to lipid peroxidation at the higher iron concentrations. None of the fractions inhibited ascorbate-dependent peroxidation in the presence of added iron salts.