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Biomedical subjects

P Rihet

Publications and source records attributed to P Rihet.

22 records · Page 2Linked to original sources
PubMedDate not supplied

Comparison of pathology in susceptible A/J and resistant C57BL/6J mice after infection with different sub-strains of Plasmodium chabaudi.

Susceptible A/J and more resistant C57BL/6J mice were infected with Plasmodium chabaudi chabaudi 54X, P.c. chabaudi AS and Plasmodium chabaudi adami 408XZ. As expected, most C57BL/6J mice survived the infections with the different isolates. But in contrast to previous observations, not all A/J mice succumbed to infection: just over 50% of A/J mice survived infections with P.c. chabaudi 54X, while 80% survived P.c. chabaudi AS. The more virulent parasite, P.c. adami 408XZ, was able to kill all A/J mice and 20% of C57BL/6J mice after an intravenous infection with 10(5) pRBC. A detailed study of four parameters of pathology (body weight, body temperature, blood glucose and RBC counts) in both mouse strains after a P.c. adami 408XZ infection showed similar patterns to those previously reported after infection with P.c. chabaudi AS. These data suggest that environmental factors as well as parasite polymorphisms might influence the severity of malaria between susceptible and resistant mice.

Animals↗
PubMedDate not supplied

Levodopa-induced drowsiness in healthy volunteers: results of a choice reaction time test combined with a subjective evaluation of sedation.

The aim of the present study was to assess levodopa (L-Dopa)-induced drowsiness in healthy volunteers using two parameters: choice reaction time and a subjective rating of sedation. Sixteen subjects participated in a randomized, double-blinded, crossover study. A single dose of 200 mg L-Dopa or placebo was administered at 9:00 AM. To limit peripheral side effects connected with L-Dopa, subjects were treated with 20 mg domperidone three times daily. Subjective rating of sedation consisted of visual analogue scale. Reaction time was measured by means of responses to two light-emitting diodes. The illumination of one of these diodes constituted the imperative signal. Manual responses were performed on two buttons located under the right and left index fingers. Results demonstrated a positive correlation between sedation level and reaction time (r = 0.70, p = 0.0026). Adverse events of L-Dopa were nausea (four cases) and excitation (one case). Subjects who did not develop adverse events were faster under L-Dopa than under placebo (p = 0.02), whereas subjects who had nausea or excitation were slower. A single dose of L-Dopa either deteriorated or improved choice reaction time in healthy volunteers according to whether it was sedative and whether it generated disruptive adverse events.

Adult↗
PubMedDate not supplied

[Analysis of the genetic factors controlling malarial infection in man].

Genetic factors have clearly been shown to play a role in controlling malarial infection in animal models. There is now also increasing evidence for the genetic control of malaria in man. We carried out a segregation analysis based on blood parasite load phenotype for a population of the town of Bobo-Dioulasso (Burkina-Faso). This analysis demonstrated a strong genetic effect. Our results were not consistent with the segregation of a major gene and thus suggest that parasite load is under the control of minor genes. The genetic effect was stronger in children than in adults. We carried out a regression analysis in children and found that there was an association between the phenotype for blood parasite load and the q31-33 region of chromosome 5. We identified a gene in this region, Pfil1 (Plasmodium falciparum infection levels 1), which accounted for almost 50% of the variance in blood parasite load and which played a fundamental role in the control of infection. The 5q31-33 region contains several genes encoding cytokines that regulate T lymphocytes. The identification of genes controlling malarial infection opens up new possibilities for preventive and treatment strategies. It should be possible in the near future to identify individuals at risk of malaria, who would derive the greatest benefit from preventive and therapeutic measures. Finally, a deeper understanding of these genes controlling protective immune responses could be of value for the development of vaccines.

Adolescent↗