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Biomedical subjects

J Lunec

Publications and source records attributed to J Lunec.

211 records · Page 12Linked to original sources
PubMed1980

The response of murine lymphoma cells - L5178Y S & R - at heat at 44 degrees C.

Two murine lymphoma cell lines L5178YS and L5178YR were exposed to heat at 44 degrees C. In comparison with other cell lines there were found to be among the most sensitive to the lethal action of heat studied to date. The difference between these cell lines in response to heat was very small when compared to the differences observed with ionizing radiation. The pattern of leakage of radiolabelled leucine at 44 degrees C was measured in each cell line and small changes compared with the behavior at 37 degrees C were observed. No net breakdown or loss of preformed protein was observed during heating nor did any labelled protein leak from the cells.

Animals↗
PubMed1980

The influence of pH on the enhancement of radiation damage by hyperthermia.

HeLa-S3 cells were treated with heat and/or radiation in medium of pH 7.4 or pH 6.7. A heat treatment at 44 degrees C for 10 min, which alone did not produce any measurable cell killing, was found to enhance the lethal effect of radiation to the same extent at pH 6.7 and 7.4. Heat alone at 44 degrees C for 30 min killed 65 per cent of cells at pH 7.4 and 90 per cent at pH 6.7 and produced a marked radiation sensitization of the survivors but only slightly more at pH 6.7 than at pH 7.4. These results support the suggestion that heat damage responsible for increase in sensitivity to subsequent irradiation is distinguishable from damage which leads to cell death after heat alone, and that heat used as a radiation sensitizer may only give a small therapeutic gain in cancer treatment, based on the lower pH of some tumour cells.

Cell Survival↗
PubMed1979

Fluorescent lipid-peroxidation products in synovial fluid.

1. Samples and extracts from synovial effusions were examined for the presence of fluorescent degradation products of free-radical oxidation (peroxidation). 2. Two classes of fluorescent compounds were identified and their fluorescence and physical properties are described. The fluorescence in the aqueous methanol phase of the extracts had the characteristics of conjugated Schiff bases. 3. Changes in synovial fluid and synovial fluid extracts in vitro induced by u.v. irradiation, prolonged incubation and the enzymic generation of oxidizing free radicals, with or without admixed peroxidizing arachidonic acid, and in the absence and presence of antioxidants, suggest that the fluorescent material is derived from peroxidized polyunsaturated lipids in damaged synovial tissue.

Arachidonic Acids↗
PubMed1978

The response of E. coli Bs-1 to tritium-beta particles under aerated and anoxic conditions.

E. coli Bs-1 cells were exposed to acute doses of tritium-beta particles by suspension in tritiated water for known lengths of time. The resulting survival rate was compared with that obtained for external irradiation with 7 MeV electrons. The o.e.r. measured for tritium-beta s was not significantly different from the value of 2.15 measured for 7 MeV electrons. The r.b.e. of the tritium beta s relative to 7 MeV electrons was 1.21 in both air and nitrogen. These results were compared with existing data for low voltage electron irradiations and with track segment studies of the effect of varying LET on the radiosensitivity of E. coli Bs-1.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

Probing molecular changes induced in DNA by reactive oxygen species with monoclonal antibodies.

Antibodies reactive with native double stranded DNA are characteristic of the chronic inflammatory disease systemic lupus erythematosus. Native DNA is however, a poor immunogen and the mechanism of anti-DNA antibody production is incompletely understood. Modification of DNA can increase its immunogenicity and in inflammatory disease states reactive oxygen species produced from phagocytic cells have been shown to thus modify DNA. In this study, monoclonal antibodies produced spontaneously by two mice strains with lupus-like disease were used in a competition ELISA to monitor changes to DNA induced by reactive oxygen species. Different procedures for reactive oxygen species generation were found to cause distinct and characteristic changes to DNA involving modifications of base residues, the sugar-phosphate backbone and the gross conformational structure of double-stranded DNA. In view of this, it may be possible to use these antibodies further to probe DNA and infer the source and nature of the reactive oxygen species it has been exposed to, particularly in vivo.

Antibodies, Antinuclear↗
PubMedDate not supplied

Increased diene conjugates in diabetic subjects with microangiopathy.

Free radicals are highly reactive unstable chemical species which have been implicated in the vascular damage associated with several disease states. Diene conjugates, probable products of free radical activity on lipids, were measured spectrophotometrically in 26 diabetic patients with microangiopathy, 36 uncomplicated diabetic patients, and 36 healthy controls. Total diene conjugates and diene conjugate to triglyceride ratios were significantly elevated in diabetic patients with microangiopathy (0.57 +/- 0.08 and 0.31 +/- 0.14 OD units/ml respectively; mean +/- SD) when compared with patients without complications (0.32 +/- 0.10, p less than 0.001, and 0.17 +/- 0.06, OD units/ml, p less than 0.011). There was no difference in total diene conjugation and their ratio to triglycerides between healthy controls and uncomplicated diabetic patients and the results were not influenced by the type of diabetes or level of diabetic control. Diene conjugate ratios repeated in 14 patients on two occasions, 6 weeks apart, with stable metabolic control were consistent. Increased diene conjugation suggesting increased free radical activity is associated with microangiopathy and this may have pathogenetic implications.

Adult↗
PubMedDate not supplied

Cholesterol content and heat sensitivity of nine mammalian cell lines.

The cholesterol, phospholipid and protein contents of nine mammalian cell lines, three lymphoid and six attached cell lines, were measured, along with the sensitivity of the cells to hyperthermia at 42 degrees and 44 degrees C. The free cholesterol content and the protein content per cell correlated positively with the time required to kill 99 per cent of the cells at 44 degrees C. The phospholipid content showed a less significant positive correlation whilst the cholesterol ester content and the cholesterol:phospholipid molar ratio did not correlate with heat sensitivity. There were no correlations observed when the levels of these cell components were compared to heat survival at 42 degrees C. As the three lymphoid lines are small, very heat sensitive cells, the six monolayer lines were analysed separately. In this case, only the protein and the free cholesterol content maintained a significant correlation (at the 5 per cent level). It is concluded that the levels of cholesterol or phospholipid cannot be used as reliable indicators of the heat sensitivity of a cell.

Animals↗
PubMedDate not supplied

Free-radical oxidation (peroxidation) products in serum and synovial fluid in rheumatoid arthritis.

Free-radical oxidation (peroxidation) products were measured in (a) 65 synovial effusions and (b) 30 sera from normal subjects and 58 sera from patients with rheumatoid arthritis (RA). Free-radical oxidation products were detectable in 90% of synovial fluids, their concentration being higher in "inflammatory" than in "degenerative" joint disease. Free-radical oxidation products in serum were significantly elevated in patients with RA compared to normal controls; the levels declined after treatment with a variety of antiinflammatory agents.

Adult↗