PubMed Health⌕ Search

Biomedical subjects

R Latarjet

Publications and source records attributed to R Latarjet.

At least 19 recordsLinked to original sources
PubMed1985

[Comparison of chain breaks produced in DNA in vivo by gamma rays and neutrons; hypothesis of a new DNA radiolesion].

Using the method of alkaline elution for the treatment of cell DNA in chinese hamster fibroblasts irradiated with low doses of either cobalt-60 gamma rays or p (34 MeV) Be neutrons, we determined the kinetics of radio-induced strand breaks. The comparison gamma rays-neutrons reveals important discrepancies which suggest that neutrons induce a so for unknown reaction in DNA simultaneously with single and double strand breakage. This observation could contribute to explain the high RBE value of high LET particles.

Animals↗
PubMed1983

In vitro propagation of the scrapie agent. I. Transformation of mouse glia and neuroblastoma cells after infection with the mouse-adapted scrapie strain c-506.

Seven cell lines including glia cells from mouse brains and mouse neuroblastoma cells were infected with the mouse-adapted scrapie strain c-506. During the early in vitro passages, a stimulation of growth was already observed but cellular morphology and differentiation did not alter. Later on, after 12-16 passages, six of the seven infected lines displayed cell proliferation and morphological alterations, suggesting an in vitro morphological transformation. At this stage, differentiation was no longer observed in the scrapie-infected neuroblastoma cells and all the scrapie-infected cells formed two to four times more colonies in liquid medium than the controls, and developed large tridimensional colonies in agar. The part played by the scrapie agent in these changes is discussed.

Animals↗
PubMed1983

Relative efficiencies of three ultraviolet radiation wavelengths for cell killing and transformation in mouse cells in vitro.

C3H 10 T 1/2 clone 8 mouse cells were irradiated in vitro with three U.V. wavelengths 280, 254, and 230 nm. Two effects were investigated, survival and malignant transformation, and the relative efficiencies were determined for the three radiations. For transformation, these efficiencies were: 280nm:3.9; 254nm:5.1; 230nm:2.3 (transformations produced by 5 Jm-2 of U.V. for 1000 surviving cells). For cell killing the efficiencies were, in relative units, 34, 100, and 50 respectively. These efficiencies are in agreement with the hypothesis that the main chromophore for both effects is the nucleic acid, and not the protein moiety of the genome. This conclusion agrees with that previously reached by other investigators, but our present results obtained with the short wave-length 230 nm provide an especially strong new argument.

Animals↗
PubMed1982

[In vitro modification of the morphology and the growth of cells infected with scrapie (author's transl)].

Seven cell lines originated either in brains or in neuroblastomas of Mice, were infected with Scrapie. After 12 to 16 in vitro passages, 6 lines out of 7 showed changes of their morphology, and of their growth, resembling those occurring in the course of a malignant transformation. The Scrapie infected cells acquired the capacity to form 2 to 4 times more colonies in liquid medium than the controls, and to develop large tridimensional colonies in semisolid medium. The role of Scrapie in these changes is discussed.

Animals↗
PubMed1981

[Trials of in vitro propagation of the scrapie agent in mouse nerve cells].

We attempted to propagate the Scrapie agent in vitro in glia and neuroblastoma cells of Mice. Four out of seven assays of infection were positive, i.e. after several passages in vitro yielding at most a 10(9) fold final dilution of the original material, the extracts of each of the four cultures, when injected intracerebrally into CD1 Mice, produced a deadly disease displaying the clinical and pathological signs characteristic of Scrapie.

Animals↗
PubMed1979

Photochemotherapy (PUVA) of psoriasis using 3-carbethoxypsoralen, a non-carcinogenic compound in mice.

The carcinogenic risk of photochemotherapy (PUVA) with bi-functional furocoumarins such as 8-methoxypsoralen (8-MOP) which form cross-links in cellular DNA has initiated a search for active but less hazardous psoralens. A new compound, 3-carbethoxypsoralen (3-CPs), studied in the yeast Saccharomyces cerevisiae (eukaryote), has been shown to be very photoactive on DNA and to form only mono-additions to DNA. These lesions appear to be more easily repaired than the cross-links induced by 8-MOP. 3-CPs produces less nuclear genetic events such as nuclear mutations and mitotic crossovers, but more cytoplasmic 'petite' mutations (damage to mitochondrial DNA) than 8-MOP. In mice it was demonstrated that after local or intra-peritoneal administration, in contrast to 8-MOP, 3-CPs is non-toxic, non-erythematogenic, and non-carcinogenic. A study of ten psoriatic patients had shown that local applications of 3-CPs plus UV-A exhibit about the same therapeutic activity for the clearing of psoriatic lesions as local treatment with 8-MOP plus UV-A, but without any localized hyperpigmentation.

Animals↗
PubMed1979

Regulation of radiation pollution: its possible usefulness in strategy for intervention against chemical mutagens.

Over the last 25 years, a large amount of work has been carried out in the field of safety with regard to ionizing radiations. This has resulted in the establishment of norms of security which have been accepted in most countries. These norms are not perfect; they are constantly reviewed and, from time to time, revised; but, such as they are, they are of tremendous usefulness. These standards may serve as a model of what must be achieved in the field of pollution by chemical mutagens. Further, the norms already in force for radiation may serve as a reference for the establishment of similar norms for the major environmental mutagens. It is not possible to assign a specific factor of equivalence with radiation (rad-equivalence) to a given chemical pollutant; but it is possible to establish point-equivalences with regard to well-defined biological systems under well-defined conditions. When they are accurately determined, such point values may be useful and sensible. In this area, as with radiation, it is impossible to find perfect solutions; however, approximate solutions can be arrived at that would already represent a reat progress with regard to the present situation, and which could later be improved as work in the field allows.

Benzopyrenes↗
PubMed1978

Unusual resistance to ionizing radiation of the viruses of kuru, Creutzfeldt-Jakob disease, and scrapie.

The titers of several preparations of kuru. Creutzfeldt-Jacob disease, and scrapie viruses were reduced by only 1/10th or less by high doses of gamma radiation of 50 kGy and by only 1/10th-1/1000th or less for 200 kGy. This unusual radiation resistance of the two human viruses further links them with the scrapie virus and suggests that the genetic information of all three viruses is considerably smaller than that of any other known viruses of mammals.

Creutzfeldt-Jakob Syndrome↗
PubMed1978

Ultraviolet light induction of skin carcinoma in the mouse; influence of cAMP modifying agents.

A short review of pathogenic factors in U.V. light skin carcinogenesis in the mouse is presented. Caffeine and theophylline applied locally during U.V. irradiation caused a 50 percent reduction of skin tumour induction in Swiss mice. These two chemicals are inhibitors of DNA postreplication repair, but they also raise the intracellular level of cyclic AMP by inhibiting cAMP phosphodiesterase with, as a consequence, a possible slowing down of cellular growth. Control experiments using three different chemicals capable of raising the cAMP level in epidermal cells gave negative results. These experimental data are compatible with our original hypothesis according to which production of skin cancers by U.V. radiation is in same way related to DNA repair which helps the cell to survive but allows or favours the occurrence of errors in cellular DNA.

Animals↗
PubMed1978

Inhibition of skin carcinogenesis in vivo by caffeine and other agents.

The induction of skin cancer in mice of the Swiss (Carshalton) strain, by repeated irradiation with UV-light, was strikingly reduced by the local application of caffeine prior to each exposure. Theophylline displayed the same activity. These two substances have been selected as probable inhibitors of error-prone, postreplicative DNA repair. Conversely, reductone and chloroquine, which are considered as inhibitors of the error-free, prereplicative excision repair, did not modify the incidence of the tumors. Special emphasis has been given to the histologic behavior of radiolabeled caffeine in the normal and UV-irradiated epidermis of the mouse in vivo and to the ability of mouse epidermal cells in vitro to repair DNA after UV irradiation.

Animals↗