Actomyosin organisation for adhesion, spreading, growth and movement in chick fibroblasts.

Examination of the actomyosin structures and their relation to adhesion, movement and growth in the first fibroblasts migrating from chick heart explants shows striking differences with fibroblasts adapted to grow in culture. The latter have focal adhesions which seem to immobilize them for anchorage-dependent growth, rather than facilitate their movement. The fibroblasts specialized for movement from the explants, though equally well spread, make contact with substratum through extensive areas of relatively unspecialized membrane, have less well developed stress fibres and a low growth rate.     

A plasma subunit vaccine against hepatitis B studied in field trials

The work presents materials on the study of subunit plasma vaccine against hepatitis B (HB), developed in the USSR, in a controlled epidemiological trial. The study showed low reactogenicity and complete safety of the preparation, the level of anti-HBsAg antibodies in persons, formerly found to have no such antibodies, being 88% after three injections of the vaccine. To determine the prophylactic effectiveness of the vaccine, the test and control groups, each consisting of 500 children, were formed from children aged 1-3 years, i.e. belonging to the age group most frequently affected by HB, by the method of random choice. During 18 months from the time of immunization no cases of HB were registered among the vaccinees, while in the control group 5 cases of HB were registered (8.9 per 1000). These results indicate that the plasma vaccine against HB, newly developed in the USSR, is faintly reactogenic, safe and shows sufficiently high antigenic activity and protective potency correlating with this activity.     

beta-Hexosaminidase expression in chick embryo fibroblasts in vitro.

1. Two forms of beta-hexosaminidase, similar to hexosaminidase A and hexosaminidase C, were separated by DEAE-cellulose chromatography in chick embryo skin fibroblasts in vitro. 2. beta-Hexosaminidase specific activity increases during development in cultured chick embryo skin fibroblasts in vitro. 3. Concanavalin-A treatment determines the increase of the neutral form, hexosaminidase C, during development. 4. Concanavalin-A reduces the specific activity of beta-hexosaminidase during development.     

Regulation of glucose transport in chick fibroblasts: bicarbonate, lactate and ascorbic acid.

The rate at which chick embryo fibroblasts in primary or secondary culture transport glucose or 3-O-methyl glucose is strongly influenced by the presence of bicarbonate ion in the culture medium. Cells growing or maintained on glucose at physiologic concentration (5.5 mM) have an 8 to 10 fold higher rate of glucose uptake than their counterparts cultivated without bicarbonate. These cells also produce more lactate as a consequence of their more rapid intake of glucose. The hydrogen acceptors, methylene blue and dehydroascorbate added to the culture medium reduce the cell capacity to transport glucose and 3-O-methyl glucose to levels obtaining in the bicarbonate-free medium. There is a concomitant reduction in glucose utilized by cells during 24 hours and further reduction in lactate formed per molecule of glucose metabolized.     

Binding and internalization of 125I thrombin in chick embryo fibroblasts: Possible role in mitogenesis

Human α thrombin acts as a mitogen for cultures of resting chick embryo fibroblasts (CEF) in serum free medium. The use of ¹²⁵I-labeled thrombin shows that thrombin specifically binds to CEF and that after a lag of approximately 30 to 60 minutes it can not be removed by subsequent exposure to trypsin. The entry of ¹²⁵I thrombin into the trypsin-insensitive domain is not inhibited to any great extent by excess unlabelled thrombin. The cell-associated thrombin retains its native molecular weight and its catalytic activity toward synthetic amide substrates. It appears to be located in the crude nuclear fraction of homogenized CEF cells. The association of thrombin with CEF is specific, since the non-mitogenic serine protease chymotrypsin is internalized to a much lesser extent than thrombin. The data are discussed in terms of a possible intracellular site for thrombin's mitogenic action.     

Phospholipid turnover in hamster and chick embryo fibroblasts

The stability of the glycerol backbone of phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine was measured in growing and non-growing hamster and chick embryo fibroblasts. Major differences were found for the rates of degradation of the individual glycerophospholipids in both hamster and chick embryo fibroblasts: considerable degradation of phosphatidyl choline was detected over a 24 h period while at the same time no degradation of the glycerol backbone of phosphatidyl ethanolamine and phosphatidyl serine was observed. The patterns of stability of these glycerophospholipids were similar in growing and non-growing cells.     

Globin synthesis in fibroblasts fused with erythroblasts. I. Avian fibroblasts.

Heterokaryons of chick embryo erythroblasts fused with other avian fibroblasts were studied with regard to globin production. After the incorporation of radioactive amino acids, soluble proteins were separated on SDS-urea polyacrylamide gels. There was a striking increase in radioactivity above background in the globin region from lysates of fusion cultures when compared with fibroblast cultures. This was maximal at 24 hours after fusion, and then declined. Electrophoresis on acid-or alkaline-urea gels further identified the material as globin chains. Tryptic digestion and fingerprinting revealed methionine-labeled peptides characteristic of chick embryo erythroblast globin. An apparent stimulation of globin chain synthesis by heterokaryons compared to erythroblasts was found to be due to a difference in the specific activity of the precursor amino acid pools in the different cell types.     

Lysozyme: evidence for effects on chick fibroblasts, HeLa cells, and their products.

Lysozyme can be shown to modify chick fibroblast morphology, glucose uptake, and Con A binding. Short treatment (30 min) of hexosamine labeled monolayers with lysozyme results in the release of hexosamine label from acid-insoluble products. Lysozyme antiserum and an inhibitor of lysozyme (trisaccharide of N-acetylglucosamine) partially protect cells from the effects cited.