PubMed Health⌕ Search

Biomedical subjects

D Dupouy

Publications and source records attributed to D Dupouy.

At least 55 records · Page 3Linked to original sources
PubMed1987

[Early diagnosis and surveillance of congenital toxoplasmosis. The comparative immunological profiles method].

More than 8000 samples (sera, cord blood, CSF, etc.) from patients who had, or were likely to have, toxoplasmosis were studied by the CIP-ELIFA technique. The first stage in this technique is immunoelectrodiffusion on a microporous cellulose acetate membrane. In the second stage, immunodetection and isotypic characterization of the precipitating systems are rapidly carried out by immunofiltration with anti-IgG, IgM, IgA or IgE-labelled antibodies (enzyme-linked immunofiltration assay or ELIFA). Several samples are jointly laid out on the same membrane for compared immunological profiles (CIP). When applied to the mother-foetus relationship in toxoplasmosis, this procedure provides an early diagnosis of congenital infestation in 85% of the cases. Positive criteria are based on evidence of specific IgM, IgE or IgA in the child, but also on the detection of foetal or neonatal antitoxoplasmosis IgG which can be distinguished from the IgG transmitted by the mother. Polyisotypic supervision is of considerable value for assessment of prognosis and of therapeutic effectiveness at the end of treatment. Satisfactory isotypic characterization can only be achieved by using particular functional antigens.

Antibodies↗
PubMed1987

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↗
PubMed1987

Hepatic cholesterogenesis and cholesterol 7 alpha-hydroxylase activity in hamsters fed diets enriched with pectins and/or cholesterol.

Cholesterol 7 alpha-hydroxylase activity was determined in parallel with the rate of cholesterogenesis from acetate and mevalonate in the liver of hamsters fed diets enriched with pectins (5%) and/or cholesterol (0.1%). Cholesterol feeding reduced the rate of incorporation of the precursors into cholesterol. Moreover, the radioactivity derived from mevalonate was found mainly in the esterified form of the newly synthesized molecules. In parallel, cholesterol 7 alpha-hydroxylation decreased by 50%. Pectins did not greatly affect hepatic cholesterogenesis or 7 alpha-hydroxycholesterol formation. In contrast, the fibers prevented to a large extent the metabolic alterations resulting from cholesterol feeding. Cholesterogenesis from mevalonate remained active; ester formation declined and the activity of cholesterol 7 alpha-hydroxylase persisted. Pectins could maintain the activity of this enzyme through multiple mechanisms, one of them being the channeling of substrate into the specific compartment of cholesterol which is destined to form bile acids.

Acetates↗
PubMed1986

Effect of pentosan polysulphate administration in man on the formation of covalent complexes between heparin cofactor II and thrombin generated in plasma by contact activation.

An assay for the quantification of pentosan polysulphate (PPS) in plasma is described. As PPS has been shown to potentiate thrombin inhibition by the second heparin cofactor (HC II), the principle of this assay was to measure the formation of covalent complexes between HC II and the thrombin generated in plasma after contact activation and recalcification. The complexes were quantified by using purified 125I-HC II added to the plasma as a tracer and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The assay was sensitive to low PPS concentrations (limit of detection: 0.1 microgram/ml) and therefore suitable for the measurement of PPS in plasma after its administration to man. The clearance of PPS was studied in 3 subjects receiving respectively 10, 50 and 100 mg intravenously (IV) and in 3 subjects receiving 35 mg subcutaneously (SC). PPS was still detectable 8 h after 50 and 100 mg IV and 6 h after 35 mg SC. The activated partial thromboplastin time (APTT) was, in comparison, relatively insensitive but for concentrations above 1 microgram/ml the values derived from the APTT and from the SDS-PAGE method fitted. The results were also in general agreement with those reported by McGregor et al. (5) who used a sensitive competitive binding assay. This indicates that low concentrations of PPS previously measured chemically are also pharmacologically active in plasma.

Adult↗
PubMed1986

Heparin fractions with high and low affinities to antithrombin III are cleared at different rates.

The clearance characteristics of standard heparin (SH) and its fractions with high and low affinity to antithrombin III (HAH and LAH respectively) were studied by injecting 125I-labelled SH, HAH and LAH intravenously into the rabbits in increasing doses. Serial blood samples were then collected from an indwelling cannula for measurement of clearance, based both on radioactivity and anticoagulant activity. For equivalent weights injected, the radioactivity of HAH was cleared more slowly from the circulation than that of either SH or LAH. The radioactivity of SH, in turn, was cleared more slowly than that of LAH. The clearance of HAH, measured both by radioactivity and by anticoagulant activity were similar, whereas the clearance of the radioactivity of SH was more rapid than its anticoagulant activity (i.e. anti-factor Xa activity). These observations suggest that the radioactivity clearance curves of SH reflect a "net" estimation of the more complex clearance curves of the different heparin moieties whereas the anticoagulant clearance curves of SH reflects the clearance of the anticoagulant activity of a specific heparin fraction, in this case, the clearance of the anti-factor Xa activity of HAH. These differences suggest that the HAH:LAH ratio is, at any given time, greater in vivo than the same ratio measured in vitro.

Animals↗
PubMed1986

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↗
PubMed1985

Turnover study of heparin cofactor II in healthy man.

Heparin cofactor II (HC II) is a heparin-dependent inhibitor of thrombin, distinct from antithrombin III (AT III). This study was designed to evaluate its metabolism in healthy subjects. Purified HC II was labelled with 125I by the lactoperoxidase-glucose oxidase technique. The biological activity of the HC II was unchanged after labelling as was its migratory pattern by crossed immunoelectrophoresis in the presence of heparin or dermatan sulfate. Three healthy volunteers were injected with 10 microCi and the plasma radioactivity was measured daily. The data were approximated by a sum of two exponential terms and the metabolism of HC II was described by a two compartment mamillary system. The mean values of fractional catabolic rate, intravascular fraction and half-life of the elimination phase were respectively: 0.44 d-1, 0.60 and 2.53 d. These parameters are of the same order of magnitude as those reported in the literature for AT III. The plasma HC II concentration in the 3 subjects ranged from 61 to 82 micrograms/ml as estimated using our purified preparation. Accordingly, the absolute catabolic rate ranged from 1.17 to 1.36 mg X kg-1 X d-1.

Adult↗
PubMed1985

Constitutional heparin co-factor II deficiency associated with recurrent thrombosis.

The family of a 36-year-old man with recurrent deep venous thrombosis and heparin co-factor II (HC II) deficiency was investigated for this deficiency. The deficiency was inherited as an autosomal dominant trait. 4 members of the family had low HC II levels but only the proband had a history of thromboses; however, 2 of 4 affected were only 14 and 23 years old. The deficiency did not affect the anticoagulant action of heparin, with which the patient was treated.

Adolescent↗
PubMed1985

Studies on catalase, glutathione peroxidase and superoxidismutase activities in aging cells of Paramecium tetraurelia.

The nature of the aging process has been the subject of considerable speculation. Now, some data indicate that free radical reactions going on continuously in the cells contribute to aging. Considering these data, we have investigated the activity of enzymes (catalase, glutathione peroxidase, superoxidismutase) present physiologically in the cell to limit to tolerable levels, the rate of free radicals or H2O2. These enzymes activities were assayed in Paramecium tetraurelia as clonal age increased. Catalase activity increases slightly during aging of paramecia, i.e. during maturity and senescence phases (20-150 fissions). No significant changes in glutathione peroxidase and superoxidismutase is found. Catalase activity was also assayed as a function of culture conditions. As the cells begin starving and the percentage of autogamous cells increases, catalase activity decreases. After autogamy, a large increase of catalase activity occurs during the sexual immaturity phase, i.e. during the first 20 fissions. By another way, H2O2 added in the culture medium (from 0 to 15 X 10(-5)M) causes an important increase of catalase activity (from 100 U.I. to 250 U.I.). The possible role of O-.2, OH. and H2O2 in aging is discussed.

Animals↗
PubMed1983

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↗
PubMed1980

Effects of autogamy in Paramecium tetraurelia on catalase activity and on radiosensitivity to natural ionizing radiations.

Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity to natural ionizing radiations--the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. The role of the catalase in the mechanism of natural iradiation effect is discussed.

Animals↗
PubMed1980

[Value of the histoenzymologic characterization of esterases in normal and pathologic rectal mucosa in children. Preliminary results of 30 cases].

The presence of cholinergic nerve fibers is studied in 30 suction rectal biopsy specimens from 5 days to 7 years old children. An increase in numbers and size of cholinergic fibers in the lamina propria and muscularis mucosae and absence of submucosa ganglion cells are related to 7 Hirschsprung's diseases. In the neonates acetylcholinesterase activity may not be strong enough to stain cholinergic fibers and makes the diagnosis more difficult.

Child↗