Influence of short and long duration exposure to hypergravity in a single-cell organism, Paramecium tetraurelia.
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Animals↗
Biomedical subjects
H Planel
Publications and source records attributed to H Planel.
Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation.
Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.
Animals↗
Radiation stimulation during the early stationary growth phase in Synechococcus lividus and its correlation with photooxidative stress occurring before the stationary phase.
The effects of chronic gamma radiation at dose rates ranging from 0.058 mGy d-1 on growth rate calculated during the early stationary phase were studied. A stimulatory effect occurred for all doses and for all phases of the cells selected for use in the inoculation of the medium. During the same period, the rate of nucleic acid synthesis was increased in irradiated cultures compared to control cultures. The stimulating effect always occurred in cultures irradiated from the inoculation to the eighteenth day only. This result led us to conclude that the stimulation mechanism depended upon the events occurring at the end of the exponential phase in the deceleration period. Studies on cell metabolism showed that cells presented features of photooxidative stress in this period. Increases in superoxide dismutase, glutathione reductase and glucose-6-phosphate dehydrogenase were observed in irradiated cultures. It was assumed that irradiation at very low doses could help cells to better defend against photooxidative stress by increasing oxidants that activate the glucose metabolism and C5-sugars production and nucleic acid synthesis.
Cyanobacteria↗
Preliminary results of the "Paramecium" experiment.
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Animals↗
Influence of very low doses of ionizing radiation on Synechococcus lividus metabolism during the initial growth phase.
Previous results from this laboratory have shown that very low chronic doses of gamma radiation can stimulate proliferation of the Cyanobacterium Synechococcus lividus. This modification of cell proliferation occurred during the first doubling. In this paper, we have compared the metabolism of cells cultivated in a normal environment or under chronic irradiation. Incubation of the cells in a new medium induced a high superoxide dismutase (EC 1.15.1.1, SOD) activity at the 18th hour and a degradation of phycocyanin, thus demonstrating that cells were submitted to a photooxidative stress. This increase in superoxide dismutase activity was followed by concomitant peaks of glutathione reductase (EC 1.6.4.2, GR) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6P-DH) at the 24th hour. Irradiated cultures at a dose of 53.5 mGray/year show an earlier and higher peak of SOD, GR, and G6P-DH. In a second stage, cultures showed an earlier onset of photosynthesis under irradiation, as evidenced by an increase in pigment content and an enhancement of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13, GAP-DH). These results show that the radiostimulation is related to the activation of enzymes protecting against peroxides that were induced under oxidative circumstances and to the activation of a glucose catabolism via the oxidative pentose phosphate pathway.
Chlorophyll↗
Effects of a very low dose rate of chronic ionizing radiation on the division potential of human embryonic lung fibroblasts in vitro.
Among the various parameters that are supposed to play a role in aging at the cellular level, the "free radical theory" involves biochemical modifications that can be induced by radiation. Human embryonic lung fibroblasts were serially subcultivated at low density under chronic low dose rate irradiation (40 mrad/day) and in a normal environment. Irradiation increases cell attachment and the population doubling/day throughout their entire in vitro lifespan. Consequently, the doubling potential reached by irradiated cells was higher than that of control cultures. Finally, the total number of cells produced under chronic irradiation was 8-14 times higher than in a normal environment. These results are discussed with respect to the increased enzymatic activities (superoxidismutase, catalase, glutathion-reductase, G6PD) found in some irradiated organisms.
Cell Adhesion↗
Radiation-induced changes in late effects and in developmental capacities of exposed artemia cysts.
Artemia dry cysts from a Californian bisexual strain used in several space experiments were irradiated with 60Co gamma rays. The three cyst populations experimented could be differentiated according to their development and survival rates. The variations observed for both of these criteria were related to the age of the cysts and the selection technique. The study of radiosensitivity based on LD50 value showed that the highest radiosensitivity differences were related to the cyst selection technique and not to the age. Furthermore, the three cyst populations showed that radio-induced lethal effects were enhanced, or appeared with time, namely following the delay between irradiation and the cyst development study. The observation of late effects after irradiations or after space flights show the difficulties encountered in assessing radiative risks during long duration space flights.
Aging↗
Some ultrastructural aspects of the vitreoretinal juncture.
The ultrastructural study of the vitreoretinal juncture was carried out by comparing two groups of patients: 6 young subjects under 25 years and 6 older subjects over 70. Retinal samples were taken from the posterior pole, the equator and the extreme periphery. Our work shows that the morphological modifications of the vitreoretinal juncture during the aging process vary following location. The most original alteration, never observed before, appears in the equatorial region: it consists of a widening of the intercell space filled with fibrils adhering to Müller's cells. It builds up an adhesion zone between the vitreous and the retina which is not visible during clinical investigations; it can create a tear during the posterior vitreous detachment.
Adolescent↗
Ultrastructural investigations on two lymphoid cell lines from Niemann-Pick disease type B.
Lymphoid cell lines (LCL) were established by Epstein-Barr Virus (EBV) transformation of blood B-lymphocytes from two different patients affected with Niemann-Pick disease (NPD) type B. Those lines were severely deficient in sphingomyelinase activity (8% and 10% residual activity). Ultrastructural investigations showed in both these lines the presence of numerous osmiophilic, dense and pleiomorphic inclusions characteristic of lysosomal storage (due to the accumulation of amphiphilic lipids) similar to those observed in tissues from NPD.
Cell Line↗
Morphologic, quantitative and cytoenzymologic studies of synoviocytic and monocytic cells in synovial fluid.
The findings are presented of a morphologic, quantitative, cytochemical and cytoenzymologic study of the mononucleated nonlymphoid cells in knee synovial fluids from osteoarthritis and various inflammatory diseases. The morphologic criteria allowed the identification of subtypes, including phagocytic subtypes, among synoviocytic and monocytic cells in the fluids. The quantitative study showed an important afflux of monocytes and a hyperexfoliation of synoviocytes in the inflammatory diseases. In fluids with intermediate cellularity, the ratio of monocytes to synoviocytes allowed the differential cytodiagnosis between osteoarthrosis and arthritis. All monocytic subtypes, especially the phagocytic one, were highly significantly increased in the inflammatory diseases. A lower increase was shown by the synoviocytic subtypes, except the phagocytic one, which was not changed. Giant multinucleated synoviocytes were found in every type of disease and thus do not constitute a cytodiagnostic marker. Alcian blue staining without hyaluronidase treatment showed hyaluronate in only a small percentage of the synoviocytes. Cytoenzymologic study showed that synoviocytes and monocytes were positive for all tested hydrolases (beta glucuronidase, acid phosphatase and alpha naphthyl acetate esterase), with the reactivities always higher in the synoviocytes. The synoviocytes were always negative with peroxidase, so this reaction, although it marks only a minority of the monocytic population, can be used as an extra cytologic criterion for the discrimination of mononucleated cells in synovial fluid. There was no significant quantitative difference at the cellular level between osteoarthrosis and arthritides in the reaction to these four enzymes. The lysosomal enzymatic activity in both monocytic and synoviocytic cells confirmed their heterophagic properties. However, synoviocytic heterophagy seems to be a physiologic process, either little or not affected by inflammatory events. On the other hand, monocytic heterophagy and then the macrophagic transformation of monocytes appears to be a major aspect of intrasynovial inflammatory reactions. The question remains as to why, if a large majority of exfoliated synoviocytes comes from type A synovial-lining cells and if they belong to mononuclear phagocytic system, do they so weakly, or not at all, participate as phagocytes in the inflammatory reaction.
Acid Phosphatase↗
[Biological effects of weightlessness at the cellular level. Comparative study of cultures of Paramecia aboard the orbital station Salyut-6 and a stratospheric balloon].
In order to distinguish the effects of cosmic rays from those of weightlessness at the cellular level, we performed experiments aboard stratospheric balloon, where gravity is equal to 1 g and cosmic radiation roughly equal to that aboard Salyut-6. The results suggest that the stimulation of cell proliferation is probably due to cosmic rays, metabolic changes being related to microgravity.
Calcium↗
[Non-lymphoid mononucleated cells in the synovial fluid in arthrosis and various inflammatory arthropathies. Morphologic, quantitative and cytoenzymologic study].
This paper describes a morphologic, quantitative, cytochemical study of mononuclear non lymphoid cells in knee synovial fluid in osteoarthritis and various arthritides. Morphologic criteria allow to identify among these cells various synoviocytic and monocytic subtypes with in both types, phagocytic subtypes. Quantitative study shows in arthritides an important afflux of monocytes and a hyperexfoliation of synoviocytes. In fluids with intermediate cellularity, Monocytes/Synoviocytes ratio allows the differential cytodiagnosis between osteoarthrosis and arthritis. All monocytic subtypes and especially the phagocytic one are highly significantly increased in arthritides. Synoviocytic subtypes show a lower increase, except the phagocytic one, which is not changed. Giant multinuclear synoviocytes are found in every type of disease and cannot constitute a cytodiagnosis marker. Alcian Blue and hyaluronidase treatment show hyaluronate in a few percentage of Synoviocytes. Cytoenzymologic study shows that synoviocytes and monocytes are positive in all tested hydrolases: beta Glucuronidase, Acid Phosphatase, alpha Naphthyl Acetate Esterase, these activities being always higher in synoviocytes. With peroxidase, synoviocytes are always negative, so this reaction although it marks only a minority of monocytic population can be used as an extra cytologic criterion for discrimination of mononuclear cells in synovial fluid. In these four enzymes there is no significant quantitative difference at cellular level between osteoarthrosis and arthritides. Lysosomal enzymatic activity in both monocytic and synoviocytic cells confirms their heterophagic properties. However synoviocytic heterophagy seems to be a physiological process not or few affected by inflammatory events. On the opposite, monocytic heterophagy and then macrophagic transformation of monocytes appears as a major aspect of intrasynovial inflammatory reaction. If a large majority of exfoliated synoviocytes comes from A type synovial lining cells and if they belong to Mononuclear Phagocyte System, why do they so weakly, or not, participate as phagocytes to inflammatory reaction.
Acid Phosphatase↗
Demonstration of a biological effect of natural ionizing radiations.
The blue-green alga, Synechococcus lividus, was grown under various levels of radiations. Shielding of cultures with lead resulted in a lower cell growth rate: the reduction disappeared when a normal radiation level was restored in the lead chamber. Irradiations from a thorium source at a dose-rate 14 times higher than that of natural irradiation stimulated the growth of the algae. These results are a new demonstration of a biological effect of background radiations.
Background Radiation↗
[Mononucleated phagocytes and mesothelial cells in serous peritoneal effusion fluid].
Twenty one peritoneal effusions from patients with cirrhosis were studied in order to characterize mesothelial cells, monocytes and their vacuolated forms. Morphological investigations were performed after Papanicolaou, M.G.G. and Giemsa stains; cytochemical studies by P.A.S., Alcian Blue pH 2,5 and Sudan Black B techniques. Seven enzymatic activities were appreciated: Naphtyl Acetate Esterase, Acid Phosphatase pH 5, beta Glucuronidase, Lactico-dehydrogénase, Malico D, NADH.D and Peroxidase pH 7,6. The free mesothelial cells show a metabolic and functional active phase in which their hydrolasic equipment suggests an intense lysosomal activity only correlated to pinocytosis. Monocytes in transudates show a morphologically micro-vacuolated macrophagic transformation of pinocytic type (elicited macrophages ?); they only become cytophagic when an acute inflammation occurs (activated macrophages ?). This paper emphasizes analogy of behaviour of mesothelial cells and monocytes in transudates, but demonstrates differences in their energetic metabolisms and endocytic characteristics.
Ascitic Fluid↗
Effects of 645 MeV and 9.2 GeV protons on Artemia eggs.
Developmental capacities of Artemia eggs have been studied after exposure to 645 MeV or 9.2 GeV protons. Effects of proton irradiation were studied in comparison with 60Co gamma ray irradiation, endpoints being emergence, hatching and 4-5 day old live nauplii percentages. Effectiveness of 645 MeV protons is greater than that of 9.2 GeV protons. R.b.e. values calculated for nauplius survival is 2.3 for 645 MeV protons and 1.5 for 9.2 GeV protons. These results can be taken into account in radiation hazard estimation during space flights.
Animals↗
[Effect of the spatial environment on the mitotic activity, size and protein content of Paramecium tetraurelia].
Cell proliferation, cell volume, protein components of paramecia and chemical analysis of culture medium were studied in Paramecium tetraurelia cultures placed in space environment. The space flight resulted in a marked stimulation of cell proliferation, an increase of cell volume, a decrease of mean protein components and changes of electrolytes in the culture medium.
Animals↗
Development capacity of artemia cysts and lettuce seeds flown in Cosmos 936 and directly exposed to cosmic rays.
Developmental capacity of Artemia cysts and chromosomal aberration frequency in lettuce seeds, flown aboard Cosmos 936 have been investigated. Biological objects were located inside or outside the spacecraft. Lettuce seeds were stuck on plastic plates and sandwiched in cellulose sheets in order to discriminate the objects hit by the cosmic heavy ions from the ones not hit. The absorbed dose inside the spacecraft was about 650 mrad. Biological objects were located at different levels in the "outside" container; absorbed doses were 1.5 rad for lettuce seeds and 30 rad for Artemia cysts. There was no change in hatch-ability of Artemia cysts located inside or outside the spacecraft when eggs were tested 2-4 months after recovery, but a marked decrease was observed in eggs 9 months after the space flight. Survival of larvae and adults was normal in "inside" eggs, but decreased in "outside" eggs. Space flight also resulted in a higher frequency of single chromosomal aberrations in cells developed from "inside and outside", hit and non-hit seeds. This highest percentage of multiple chromosomal aberrations occurred in seeds hit by the heavy ions.
Animals↗
[Multiplication of Paramecium aurelis on board the orbital station Saliout-6 (Cytose experiment)].
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Animals↗