PubMed Health⌕ Search

Biomedical subjects

D Duval

Publications and source records attributed to D Duval.

At least 19 recordsLinked to original sources
PubMed1992

SL 82.0715, an NMDA antagonist acting at the polyamine site, does not induce neurotoxic effects on rat cortical neurons.

In the present study, we have examined by light and electron microscopy whether SL 82.0715, a polyamine site-directed N-methyl-D-aspartate (NMDA) antagonist, causes pathological changes in cerebrocortical neurons similar to those observed with NMDA receptor channel blockers in the rat brain. Dizocilpine (1, 2 and 5 mg.kg-1, s.c.) induced a dose-dependent vacuolization of the neuronal cytoplasm in specific neurons of the retrosplenial and posterior cingulate cortices (layers III and IV) even at the lowest dose studied, at 6 h post-injection. In contrast, SL 82.0715 (10 and 30 mg.kg-1 i.p., 6 h post-injection) did not induce such morphological alterations. These results indicate that NMDA receptor blockade is not necessarily associated with alterations of cortical neuronal morphology.

Animals↗
PubMed1992

Lactate dehydrogenase (LDH) activity of the cultured eukaryotic cells as marker of the number of dead cells in the medium [corrected].

One significant problem in monitoring a culture's evolution is to assess change in cell viability. We have demonstrated that LDH release could be a good indicator of cellular damage of many cell lines, especially during shear stress or sonication. Moreover, we have found a significant correlation between the number of dead cells, determined by Trypan Blue staining, and LDH activity measurements in the supernatant of hybridoma strains, whatever the culture conditions. We have also shown that when viability is still near 100% no LDH is released even at high cell concentrations. Therefore, LDH should serve as a potential marker of cell injury and death.

Animals↗
PubMed1992

Role of metabolic waste products in the control of cell proliferation and antibody production by mouse hybridoma cells.

In order to determine the factors limiting the proliferation and productivity of mouse hybridoma cells in batch/fed-batch cultures, we tested the influence of various environmental parameters on the growth of a model cell line VO 208. We observed that, among the major metabolic waste products, ammonium ions at concentrations superior to that present in the medium at the end of a batch culture do not exert a significant toxic effect on cell growth, whereas in contrast, lactic acid is cytotoxic at concentrations reached in cultures. Feeding of fructose instead of glucose during the stationary phase of the culture markedly prolongs the life span of the culture and enhances the antibody secretion accordingly. However, we failed to observe a satisfactory proliferation pattern in cultures grown in a glucose-free fructose-supplemented medium. We also noted that vitamin supply may be limiting in fed-batch cultures. It thus appears that thorough examination of the cell metabolic needs allows the designing of a culture regimen which significantly improves cell growth and secretion.

Ammonia↗
PubMed1992

Study on the effect of oral administration of carbocysteine on ventilatory parameters in the SO2 inhalation model of bronchitis in the rat.

In order to study the physiological correlates of the beneficial action of carbocisteine (S-carboxy-methyl-cysteine), we have measured the changes occurring in ventilatory parameters in rats made bronchitic by prolonged exposure (2 weeks) to air containing sulfur dioxide (SO2). In animals treated with distilled water (1 ml/100 g/day), statistically significant (P < 0.05) changes in respiratory frequency (-20%) and tidal volume (+31%) were found. As a result of these opposing changes, the ventilation/min was stable. Moreover, the compliance was decreased (33%, P < 0.05) and the resistance was greatly enhanced (+ 99%, P < 0.05). The concomitant administration of carbocisteine (500 mg/kg po/day) with SO2 inhalation significantly (P < 0.05) prevented the development of resistance without effecting significant changes in the other parameters except for a slight improvement in ventilation/min. In conclusion, this improved respiratory resistance in the bronchitic carbocisteine-treated animals tallies with a decrease in mucus retention associated with the return to normal of rheological characteristics of the secreted mucus.

Administration, Inhalation↗
PubMed1979

Glucocorticoid receptors in thymocytes of fetus, newborn, and adult CBA mice.

[3H]Dexamethasone binding was studied in vitro in cell suspensions of thymus from fetal and newborn mice. The number of glucocorticoid receptors appeared to be identical in fetal, newborn, and adult CBA mice. The affinities of these receptors, calculated by Scatchard analysis, were similar in the three groups of animals. The extent of in vitro steroid-induced inhibition of [3H]uridine incorporation by fetal and adult thymocyte suspensions was very similar. These results suggest that no significant variations in glucocorticoid receptors occur in thymic tissue during the neonatal period.

Aging↗
PubMed1979

Mechanism of glucocorticoid-induced inhibition of prostaglandin synthesis.

In order to study the mechanism of steroid-induced inhibition of prostaglandin (PG) secretion, we have used rat renomedullary interstitial cells grown in tissue culture as an in vitro model. These cells have been shown by radio-immunoassay to produce high amounts of prostaglandins, mainly PGE2 and PGF2 alpha. Using (3H) dexamethasone, we have demonstrated in our cultures the existence of glucocorticoid binding sites which exhibit all the characteristics of physiological glucocorticoid receptors. Comparison between the biological activity (i.e. the ability to inhibit PG secretion) of the various steroids tested (dexamethasone, corticosterone, aldosterone, progesterone and estradiol) and their affinities for the glucocorticoid binding sites reveals a striking correlation between these two parameters. Steroids which bind to the receptors also inhibit prostaglandin secretion whereas testosterone and estradiol, which have a very weak affinity for the glucocorticoid binding sites do not inhibit PG secretion. In addition, actinomycin D (0.1 microgram/ml) and cycloheximide (0.1 microgram/ml) are able to abolish the inhibitory effect of dexamethasone on PG secretion. Our results indicate that the action of corticosteroids on prostaglandin secretion, which is believed to be the basis of their anti-inflammatory properties, is mediated through receptor occupancy and requires RNA and protein synthesis.

Animals↗
PubMed1979

Human thymus cells: effects of glucocorticoids in vitro.

The level of glucocorticoid receptors and the effects of dexamethasone on 3H-Uridine and 3H-Thymidine incorporation have been determined in normal human thymus cells. Under the experimental conditions employed human thymocytes appear more steroid-sensitive in vitro than human circulating lymphocytes.

Animals↗
PubMed1978

[Macrophage origin of platelet activating factor].

Platelet-activating factor (P.A.F.) is a mediator of anaphylaxis released from human and Rabbit basophils which causes aggregation of platelets and release of their vasoactive amines. We have induced the release of P.A.F. from Rat peritoneal cells (P.C.) with ionophore A 23187. After fractionation of P.C. on 5-15% Ficoll gradients, P.A.F. was obtained from macrophage-rich but not from mastocyte-rich fractions and from adherent cells but not from non adherent cells. These data suggest an important new function for the macrophage: aggregation of platelets and release of their vasoactive amines and others mediators of inflammation.

Animals↗
PubMed1978

Chronic lymphatic leukaemia: cellular effects of glucocorticoids in vitro.

Glucocorticoid receptor levels and steroid induced inhibition of nucleic acid precursors have been examined in lymphocytes from 27 patients at different stages of chronic lymphatic leukaemia. No correlation can be found between the level of glucocorticoid receptors and the stage of the disease. On the other hand, a significant difference (P less than 0.02) was found between stage O and stage III/IV patients, in terms of the in vitro effect of dexamethasone on [3H] uridine incorporation.

Adult↗
PubMed1978

Prognostic value of steroid receptor determination in leukemia.

Determinations of steroid receptors have been used to predict steroid sensitivity in various neoplastic tumors. It appears, however, that simple steroid binding measurements are not sufficient for that purpose in lymphoid tumors. This conclusion is based on a literature survey showing, first, that numerous factors are capable of modulating cellular steroid receptor content; second, that the results of steroid receptor determinations are critically dependent on experimental procedures; and, third, that the correlation between steroid receptor content and sensitivity is not obligatory in animal or human leukemic cells.

Animals↗