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Biomedical subjects

F Simon

Publications and source records attributed to F Simon.

At least 145 records · Page 8Linked to original sources
PubMed1993

Evolution of chloroquine resistance in central and west Africa.

The evolution of in vitro chloroquine susceptibility of clinical isolates of Plasmodium falciparum obtained from travellers returning to France was studied between 1986 and 1991 using the isotopic semi-microtest. Based on the analysis of 1,147 interpretable tests on isolates originating from Central and West Africa, the study showed that the proportion of chloroquine-resistant falciparum malaria remained stable between 1986 and 1988 and has diminished between 1989 and 1991. The diminution of chloroquine-resistant imported malaria may be associated, at least in part, with a better compliance of French travellers with the recommendation to use either mefloquine or a combination of chloroquine and proguanil since 1989 and an increasing proportion of African immigrants who tend to neglect regular chemoprophylaxis during the visit to their countries. The reason for the stabilisation of chloroquine resistance is unknown, and this phenomenon may be temporary, necessitating a continuous surveillance of drug susceptibility.

Africa, Central↗
PubMed1993

Antibody avidity measurement and immune complex dissociation for serological diagnosis of vertically acquired HIV-1 infection.

Differences in avidity between HIV-1 antibodies transmitted passively and antibodies synthesized by children born to HIV-1-positive mothers can be measured using a commercially available competitive enzyme immunoassay kit. The avidity determination method is based on the competition between an anti-HIV-1-peroxidase-labeled antibody at a stable and known concentration and the anti-HIV-1 antibodies (IgA, IgG, IgM) present in the child's serum at various and increasing dilutions. The shift in the competition/dilution curves between serum samples taken at the third and the sixth month of the child's life showed either the loss or the synthesis of anti-HIV-1 antibodies. The antibody avidity determination combined with a test detecting free or complexed p24 antigen is a workable and inexpensive serological method for the follow-up of children born to seropositive mothers. Combining these two complementary methods, HIV-1 infection has been established at 6 months of age in 13 of 13 infants, and positive results were confirmed by coculture and by PCR. An HIV-1 infection was excluded at 6 months of age in 17 of 17 infants, results otherwise confirmed by virological and clinical follow-up. These new and convenient approaches to the diagnosis of vertically acquired HIV-1 could be used worldwide, including in developing countries.

AIDS Serodiagnosis↗
PubMed1992

The phase of PVEP in Maxwellian view: influence of contrast, spatial and temporal frequency.

The temporal phase of the pattern reversal VEP has been investigated using stimulation with laser interference fringes in Maxwellian view. VEP phase was almost constant as function of spatial frequency (2-30 c/deg, 6.5 r/sec, 51 subjects). The phase function however shows a small phase increase at low spatial frequencies consistent with the existence of multiple temporal mechanisms. Contrast variation yields a smaller phase increase with decreasing contrast than conventional stimulation. The phase is linear as function of reversal rate (2-31 r/sec) for low and high spatial frequencies. The indication of more than one temporal mechanism has also been found when the test field diameter was varied. With decreasing test field size the phase increases at 6.5 r/sec, but decreases at 18 r/sec (for 12 c/deg).

Adult↗
PubMed1992

Rapid determination of human cytomegalovirus susceptibility to ganciclovir directly from clinical specimen primocultures.

We were able to rapidly determine the susceptibility of human cytomegalovirus to ganciclovir using a late antigen synthesis reduction assay directly on primocultures of clinical specimens. This test was compared with a conventional susceptibility assay which was performed with cell-free virus obtained after cytomegalovirus isolation and in vitro passages. Both tests produced similar results. The rapid test, unlike conventional assays, is able to provide a result within 5 days after receipt of the specimen and could thus play a direct role in the therapeutic decision.

Cytomegalovirus↗
PubMed1992

Sulfonamide residues in eggs.

In two series of experiments lasting 3 days each, laying hens were medicated with sulfonamides via the drinking water. In the first experiment 8 laying hens were given sulfaquinoxaline (SQ) at a dose rate of 400 mg/l, while in the second trial 16 laying hens received a 3:5:5 sulfonamide mixture containing sulfaquinoxaline (SQ), sulfadimidine (SDI) and sulfamerazine (SMN), at a dose of 390 mg/l. According to the water consumption data, the hens' daily sulfonamide intake was 53.6 and 56.9 mg/kg body mass, respectively. Eggs laid during and in the first 10 days after the treatment were collected and assayed for sulfonamide residues by spectrophotometry. The detection limit of the method was 0.16 mg/l and the recovery percentage was between 70 and 80%. Sulfonamide was found to appear already in eggs laid after the first day of treatment. The absorption half-life of the drug was 0.4-0.6 day in the egg-white and 0.93-1.08 day in the egg-yolk. Peak drug level in the egg-white was measured on the last day of medication, while in the egg-yolk within 3 days after the end of treatment. The residue measured in the yolk was 13-16% of that found in the egg-white. Acetylated sulfonamide could be measured in the yolk for 3 days after the treatment: its level reached 15%. On the basis of the elimination rate, complete elimination of sulfonamides requires at least 5.2-7.4 days. Therefore, observance of the generally accepted withdrawal time of 10 days is indispensable.

Animals↗
PubMed1991

[Not Available].

Explore the source record for details and available documents.

Germany↗
PubMed1991

[Effect of equilateral administration of monensin and tiamulin on the peripheral nerve function and the electrocardiogram of broilers].

The influence of the simultaneous administration of monensin and tiamulin on the motor nerve conduction velocity and the refractory periods of the N. ischiadicus was studied on 4-week old cockerels. The combined administration of the two substances resulted in significant decrease of the conduction velocities of the peripheral nerve, while the relative and absolute refractory periods were seen to increase significantly as a result of the medications. The observed alteration of the peripheral nerve function in the early phase can already attribute to the development of the serious clinical signs of the toxic interaction. The simultaneous application of monensin and tiamulin caused also changes in the electrocardiogram which was expressed in a prolongation of the RS interval and the ST segment. At the same time the heart rate was reduced.

Animals↗
PubMed1990

[Classification of retroviruses].

The retroviridae comprise a large number of viruses. In both nature and laboratories these viruses are associated with numerous diseases, including rapid or long latency malignancies, neurological disorders and immunodeficiency. The replication cycle is characterized by integration of the viral DNA into the host's genome after the reverse transcriptase copied the viral RNA into DNA. The discovery of human retroviruses had a late start. It was not until 1980 that the first oncovirus, the human T-leukaemia virus 1 (HTLV-1), was identified. The human immunodeficiency viruses (HIV-1 and HIV-2), belonging to the lentivirus subfamily, cause AIDS. Several simian virus, called simian immunodeficiency viruses (SIV) and related to HIV-1 and/or HIV-2 have been identified in monkeys and chimpanzees.

Animals↗