Biomedical subjects
Publications and source records attributed to R Deloince.
Hepatitis A antibodies (anti-HAV) were surveyed in 1000 French recruits during 1990. The prevalence of anti-HAV in this group was 21.35%. Compared to a 1985 survey a 9% fall in the anti-HAV prevalence rate was observed. Living in a coastal area, low educational level, stay overseas were the main risk factors, as already noted in 1985.
Forty antiviral compounds were screened for inhibitory effect on hepatitis A virus (HAV) antigen expression in the human hepatoma cell line PLC/PRF/5. Ribavirin, amantadine, glycyrrhizin, and pyrazofurin were selected in this screening test and were studied further. The selectivity indices of these four compounds, calculated as the ratio of 50% cytotoxic dose (determined by the trypan blue exclusion and by inhibition of [3H] leucine incorporation) to the 50% effective dose (determined by the viral antigen expression), were 4.6 and 3.0 with ribavirin, 5.3 and 5.9 with amantadine, 15.2 and 16.9 with glycyrrhizin, and 45.4 and 74.6 with pyrazofurin. All four compounds resulted in concentration-dependent reductions of HAV antigen expression and HAV infectivity. Ribavirin, amantadine, pyrazofurin, and glycyrrhizin emerged, from the present study, as promising candidates for chemotherapy of acute hepatitis A.
Two monoclonal antibodies (813 and 10.09) were raised against hepatitis A virus (HAV). They recognize an immunodominant epitope and a neutralizing site on HAV.
Atropine, protamine, and the combination of these drugs were tested for their effects on hepatitis A virus (HAV) replication in cell culture. PLC/PRF/5 hepatoma cells were treated simultaneously with nontoxic concentrations of these drugs and inoculated with HAV strain CF 53 at several multiplicities of infection. The yields of infectious HAV after 4 and 15 days were markedly reduced by each drug, especially at the lowest multiplicity of infection. The activities of each drug were irreversible. Atropine was active when it was added as late as 2 h after inoculation with HAV. An anti-HAV effect was also induced by treating cells with atropine prior to inoculation. Protamine was active as late as 6 h postinoculation. The combination of atropine and protamine resulted in an enhanced anti-HAV effect. We concluded that these drugs affect undetermined, but separate, steps in the HAV replication cycle.
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5'-nucleotidase activity of cultured diploïd cells was measured using intact suspended cells. This depended on the substrate amount, but did not vary with Mg ++ concentration-Kinetic data were determined using Con. A,a specific inhibitor.
One of the earlier effects of poliovirus was the maintaining of a high level of Hela cells 5'-nucleotidase activity (maximal efficiency for a virus/cell ratio = 500 ID 50/cell) (ID50:50% Infections Dose). The activity decreased when cells were suspended in the presence of EDTA(EDTA:Ethylene Diamine Tetracetic Acid) and was partially restored by adding 10 mM Mg++ interactions are discussed.
An association of bacterial ribosomes and cell-wall of Klebsiella pneumoniae was shown to reduce the incidence of an epidermoid carcinoma in Sprague-Dawley rats when administered subcutaneously prior the tumoral graft. Mononuclear cells accumulate around the tumor. This association was considered as a non specific adjuvant stimulating the host's intrinsic immunity to tumor antigens.
Two fractions of ciguatoxic extracts were isolated by chromatography. The first showed anticholinesterasic properties, while the other acted directly on the muscular fibre. These findings were histoenzymologically confirmed. Controls with non-toxic extracts of fishes from the coral benthos reinforce the theory of the ecological origins of ciguatoxins.
Sulphated polysaccharides such as iota-, lambda- and kappa-carrageenans showed a potent inhibitory effect on the replication of hepatitis A virus (HAV) in the human hepatoma cell line PLC/PRF/5. No cytotoxic effects were detected with concentrations of carrageenans up to 200 micrograms/ml. The selectivity indices of these substances, calculated as the ratio of the dose that reduced the number of viable cells to 50% (CD50) to the effective dose that inhibited 50% of viral antigen expression (ED50), were greater than 400 with iota-carrageenan, greater than 222 with lambda-carrageenan and greater than 10 with kappa-carrageenan. The selectivity index of ribavirin (reference substance) was only 5. The 3 types of carrageenans resulted in concentration-dependent reduction of HAV-antigen expression and HAV infectivity. lota-and lambda-carrageenan emerged, from the present study, as promising candidates for chemotherapy of acute hepatitis A.
The use of histo-enzymological techniques for visualizing the cholinesterasic spots on the motory plate is turned to account by the authors to point out the inhibition of the cholinesterasic processes, by some fractions of the ciguatoxins at the level of the neuro-mucular synapsis. The results obtained confirm, on one hand, the efficiency of the method to test the anti-cholinesterasic activity of some fractions of the ciguateric extracts, and, on the other hand, enable the establishment of the fact that even clinically non toxic individuals from fishspecies, dwelling in tropical coral biotops, can provoke a slightly marked but real inhibition of the cholinesterases, provided the contact between the fish extract and the neuro-motory plate is long enough in time. This observation reinforces the thesis of the ecological origin of the toxins along the alimentary chain of the reef biocoenosis.