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At least 19 recordsLinked to original sources
PubMed1978

Increased susceptibility to infection with herpes simplex virus types 1 and 2 of cold-adapted L cells.

L cells (L-As subline) have been adapted to a temperature of 4 degrees C. In the cold-adapted cells, designated LC3, greater amounts of infectious herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) were synthesized than in the original L-As cells or in another control L-cell line. Two strains of HSV-1 reached higher infectious titres in LC3 cells grown at 36 degrees C than in those grown at 32 degrees C. The HSV-2 strain tested replicated in LC-3 cells grown at 32 degrees C better than at higher temperature. Increased reproduction of HSV in LC3 cells was not due to enhanced adsorption of virions on the cells as compared with control L cells. The multiplication of cold-adapted LC3 cells was and was not more intensive than of L-As and control L cells, respectively. The virological results are confronted with known physiological properties of cold-adapted cells.

Adaptation, Physiological↗
PubMed1974

Proteinase produced by Chlamydia psittaci in L cells.

L cells (mouse fibroblasts) infected with Chlamydia psittaci (strain meningopneumonitis) produced a proteinase differing in solubility in ammonium sulfate from the proteinase of uninfected L cells. Synthesis of the enzyme was inhibited by chloramphenicol but not by cycloheximide, indicating that the new proteinase in infected L cells was synthesized by Chlamydia psittaci. The chlamydial proteinase had no demonstrable ion requirements and was not inhibited by a variety of inhibitors of proteinase activity. Gel filtration experiments suggested a molecular weight of approximately 250,000. The proteinase appeared in infected L cells at the time host cells began to die and the large chlamydial cells began to reorganize into small ones. Some possible functions for the chlamydial proteinase were proposed.

Ammonium Sulfate↗
PubMed1972

Acetylcholine responses in L cells.

L cells, a family of continuous cell lines of mouse fibroblastic origin, generate a prolonged active membrane hyperpolarization (the hyperpolarizing activation response) when stimulated mechanically or electrically. lontophoretically applied acetylcholine elicits a similar response; atropine blocks the acetylcholine but not the electrically or mechanically elicited responses. The hyperpolarizing activation response can also be elicited by electrical, mechanical, or acetylcholine stimulation of cells adjacent to the recorded cell. Propagation of the response from one cell to another is not dependent on direct electrical coupling between cells and is not blocked by application of a bath containing atropine or curare. These results show that L cells are capable of generating an active electrical response. that they are sensitive to at least one neurotransmitter (acetylcholine), and that humorally mediated interaction (probably noncholinergic) between L cells occurs.

Acetylcholine↗
PubMed1984

Coexpression of the human HLA-A2 or HLA-B7 heavy chain gene and human beta 2-microglobulin gene in L cells.

L cells expressing human HLA-A2 or HLA-B7 class I antigen heavy chains are not recognized by human cytotoxic T lymphocytes directed at HLA-A2 or HLA-B7 antigens. To test whether the absence of human beta 2-m was the cause of the lack of recognition by the human cytotoxic T lymphocytes, coexpression of the human beta 2-m gene and the HLA-A2 or HLA-B7 heavy chain in L cells ("double transfectants") was obtained. In addition, L cells expressing HLA-A2 or HLA-B7 antigens in association with human beta 2-m were obtained by an exchange reaction, in which human beta 2-m from serum replaced the endogenous murine beta 2-m. Both types of transfectant cells were used in 51Cr-release assays and cold target inhibition assays for human cytotoxic T cell clones which were directed at HLA-A2 or HLA-B7. Neither human CTL clones nor a mixture of CTL specific for HLA-A2 and HLA-B7 were able to recognize these cells. Several alternative explanations for these observations are discussed.

Animals↗
PubMed1972

Metabolism of Rickettsia typhi and Rickettsia akari in irradiated L cells.

L cells that had been exposed to 3,000 r of (60)Co the previous day were used to study the growth and metabolism of Rickettsia typhi and R. akari. Viable (unirradiated) L cells were used to study the effect of rickettsial infection on host-cell metabolism. Monolayers were infected with a rickettsial multiplicity of 1.2 and given Eagle's minimal essential medium containing 25 mmN-2-hydroxyethylpiperazine-N'-2'-ethanesulfonic acid buffer and 10% calf serum. At various intervals, cycloheximide (2 mug/ml) was added to one set of cultures, to inhibit eukaryotic protein and deoxyribonucleic acid (DNA) metabolism; phosphate-buffered saline (PBS) was added to another set. After 1 hr, the cultures received a mixture of 15 (14)C-labeled amino acids or adenine-8-(14)C. The cultures were harvested 16 hr later and were tested for incorporation of labeled carbon into the fraction precipitated by cold trichloroacetic acid. Viable cells were exposed to thymidine-2-(14)C for 2-hr periods. Infectivity of R. typhi increased to a peak of 150 to 400 hemolytic units/culture on day 4; the titer remained approximately the same on days 5 and 6, and declined rapidly on day 7. Total amino acid incorporation was about the same in infected and uninfected cultures up to day 6, but metabolic activity was reduced to a negligible level on day 7 in infected cells. Cycloheximide-resistant activity was higher in the infected cultures, with a peak equivalent to one-half the total activity at day 4 to 5. Total as well as cycloheximide-resistant adenine incorporation was higher in the infected cells between days 3 and 5 after infection, with a peak at day 3 to 4. Somewhat similar results were obtained with R. akari, except that the cycle of infection and of cycloheximide-resistant activity proceeded and was completed more rapidly. (14)C-DNA of both rickettsiae was isolated from infected cultures that had received labeled adenine. With labeled thymidine, which was not incorporated by the rickettsiae, it was shown that R. typhi and R. akari differ considerably in their effects on the host cell. R. typhi elicited moderate inhibition, whereas R. akari infection led to a complete inhibition of thymidine incorporation by the third day, at the time of highest rickettsial activity. It is concluded that rickettsiae have the necessary enzymes for protein and nucleic acid synthesis, but, thus far, these enzymes have been activated or induced only in an intracellular environment.

Adenine↗
PubMed1992

A new and potent 2-5A analogue which does not require a 5'-polyphosphate to activate mouse L-cell RNase L.

In order to explore the possibility of supplanting the requirement of a 5'-triphosphate moiety for the activation of the 2-5A-dependent endonuclease (RNase L) of mouse L-cells, two new tetrameric analogues of 2-5A were synthesized. The first tetramer, obtained by both a modified prebiotic synthetic approach as well as a phosphite triester solid phase oligonucleotide synthesis method, was p5'A2'p5'A2'p5'(br8A)2'p5'(br8A). The second oligonucleotide was derived from the former by a sequence involving periodate oxidation, reaction with n-hexylamine, and cyanoborohydride reduction, resulting in conversion of the 2'-terminal adenosine residue to 9-(3'-aza-4'-hexyl-1',2',3',4'-tetradeoxyhexopyranos-1(1)-yl)-8-++ +bromoadenine. Both of these oligomers, bearing only 5'-monophosphate groups, were found to be as potent as 2-5A itself as activators of the RNase L of mouse L-cells.

Adenine Nucleotides↗
PubMed1983

Comparative studies on trypomastigotes of Trypanosoma cruzi from infected mouse blood and infected fibroblast cell (L-cell) culture.

The resistance to phagocytosis by macrophages and the penetration into fibroblast cells of blood form trypomastigotes of Trypanosoma cruzi were compared with those of trypomastigotes grown in fibroblast cell culture. On incubation for 24 h, blood form trypomastigotes were almost completely resistant to phagocytosis, but about 40% of the trypomastigotes from cell culture were phagocytized. On longer incubation, the resistance of both forms of trypomastigotes decreased gradually. The penetrating ability of blood form trypomastigotes was much lower than that of trypomastigotes from cell culture. Infection of mice with blood form trypomastigotes resulted in less proliferation of parasites in the liver and spleen than that with trypomastigotes from cell culture. From these results, the existence of two functionally different forms of trypomastigotes in infected mice and in infected fibroblast cell culture, respectively, is discussed.

Animals↗
PubMedDate not supplied

[Centrioles in the cell cycle of L cells].

The structure of centrosome in non-synchronous L-cells culture during the cell cycle has been studied. In mitosis, mother and daughter centrioles, which differ in their ultrastructure, are located perpendicularly in the pole of the spindle. Microtubules, meeting in the pole area terminate mainly in electron-dense clottings of fibrillar matter surrounding the diplosoma. In telophase, disjunction of mother and daughter centrioles begins. At the beginning of G1-period, centrioles move off from each other for several micron, and then draw together again without forming diplosome. Pericentriolar satellites form on mother centriole of some cells at this time, they disappear at the beginning of S-period, replication of centrioles begins; daughter centrioles reach the size of mother centrioles in anaphase. During growth and maturation, centrioles in L-cells undergo structural changes similar to those described for SPEV cells (Vorob'ev, Chentsov, 1982). Several types of meeting points for microtubules exist in L-cells during the whole interphase: surface of centrioles per se, pericentriolar satellites, free foci.

Animals↗
PubMed1979

[Immunological properties of malignant and nonmalignant L-cell sublines. I. Obtaining a malignant L-cell subline and its immunological cross reactivity with nonmalignant cells].

LS cells, the malignant subline of benign L cells, were obtained from L cells by selection carried out by means of their cultivation in the abdominal cavity of allogenic mice. When inoculated subcutaneously in a dose of 1 x 10(6) into the back, LS cells took and progressively grew in 70% of syngeneic animals. The preliminary immunization with L cells protected 30% of mice inoculated subsequently with L cells.

Animals↗