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Biomedical subjects

F J Louis

Publications and source records attributed to F J Louis.

At least 55 records · Page 3Linked to original sources
PubMed1994

Rhesus polymorphism in New Caledonia. I. Genetic structures of three local populations.

Rhesus phenotypes are presented for a total of 2,052 individuals belonging to three sympatric populations of New Caledonia: Kanaks (Melanesians), Wallisians (Polynesians) and Europeans born in New Caledonia. The maximum-likelihood gene frequency estimations reveal a significant deviation from Hardy-Weinberg equilibrium for the Kanak and Wallisian samples. As suggested on statistical grounds, this disequilibrium can be attributed to antigene mistypings, frequently encountered for this system. This hypothesis leads to new estimations of Rhesus haplotype frequencies for the two samples. They reveal a high degree of genetic similarity (89.6%) between Kanaks and Wallisians, with little or no evidence of admixture with Europeans from New Caledonia. The latter are genetically close to southern Europeans in having a very high R1 frequency.

Adolescent↗
PubMed1994

Rhesus polymorphism in New Caledonia. II. Genetic comparison with other Oceanians.

Rhesus haplotype frequencies computed for 804 and 546 Wallisians from New Caledonia are compared to the data collected for 13 Oceanian samples belonging to the same Austronesian linguistic family. Genetic distances are computed between the 15 populations and used for a principal coordinate analysis. Kanaks are genetically close to Fidjians, while the Wallisian sample share a high genetic similarity with the Tonga islanders. The results obtained for the whole area including the Wallis homeland for the Wallisian sample indicate a tight relationship between geographical and genetic differentiations in the Pacific, supported by a high correlation coefficient between the two distance matrices. However, the observed patterns are better explained by the history of migrations reconstructed from archaeological and linguistic data than by a pure isolation-by-distance model.

Black People↗
PubMed1994

Sickle cell trait performance in a prolonged race at high altitude.

The limitation of aerobic exercise capacity of athletes with the sickle cell trait (SCT), under conditions of limited oxygen availability, is still controversial. To study this, we took advantage of an unique setting, the International Mount Cameroon Ascent Race, a 34.1-km race over difficult terrain, slopes ranging from 7 to 40%, and altitudes varying from 615 to 4095 m, combined with high prevalence rates of SCT among the African runners. Of 266 Cameroonian runners, SCT was detected in 33 athletes (12.4%), a prevalence similar to that of the ethnically corrected general population. However, in runners of the Bakoueri tribe whose performance is contingent with social stature, SCT was present in only 1 of 41 runners (2.4%), as compared with 15.6% in the general population of the Bakoueri tribe (P < 0.03). In general, performance times of SCT runners were not different from non-SCT runners, except during the portion of the race at altitudes ranging from 3800 to 4095 m, where significantly longer times were clocked by SCT subjects (P < 0.02). We conclude that prolonged aerobic efforts in hypobaric hypoxic conditions may be associated with a detrimental effect on performance in SCT carriers. If this is true, it might account for the reduced prevalence of SCT among those runners representing the Bakoueri tribe, provided an objective measure of performance at altitude was employed to select these representatives.

Altitude↗
PubMed1993

Efficacy of micronized halofantrine in semi-immune patients with acute uncomplicated falciparum malaria in Cameroon.

Fifty subjects with acute uncomplicated falciparum malaria were treated orally with a new micronized formulation of halofantrine. The dose given corresponded to one-half the normal dose for the standard formulation. Parasitemia cleared in all subjects within 78 h. There was recrudescence of falciparum malaria in seven subjects after day 14. The mean +/- standard deviation clearance times of parasitemia and fever were 49.0 +/- 14.2 and 24.3 +/- 13.2 h, respectively. Other clinical symptoms related to malaria cleared within the first 3 days. Pruritus occurred in two subjects, back pain occurred in one subject, and diarrhea occurred in one subject; all of these symptoms were mild. Hematological and biochemical indices were not adversely affected by treatment except in five subjects in whom minor and transitory increases in aspartate aminotransferase and alanine aminotransferase were observed. Micronized halofantrine appears to be a safe, well-tolerated, and effective treatment for acute falciparum malaria in semiimmune patients.

Adolescent↗
PubMed1993

[Epidemiological features of retroviral infection by HTLV-1 in central Africa].

Subsaharian Africa is the most important reservoir of HTLV1 virus but its epidemiology is not well-known. The authors have studied from 1987 to 1990 the situation in 6 countries in Central Africa. The already described routes of transmission are present: through blood transfusions (but it's not such a common practice), heterosexual transmission (but it doesn't seem to be as important as in other continents), and mother to child transmission through breast feeding. Nevertheless, environmental factors--which have to investigated--could play a role for transmission, among them one could think to vectors and parasites.

Adolescent↗
PubMed1992

[Hepatitis B in Wallis: results of a seroepidemiological survey].

A sero-epidemiological survey was conducted on Wallis Island, in the South Pacific, from July 1988 to May 1989. A random sample from the general population was examined. 672 sera were tested for HBs antigen and anti-HBc antibody. Analysis of the data showed that there was little, if any, transmission from mother to newborn; serological markers seemed to be acquired during the first years of life, before the age of 15 years. After 15 years, seropositivity rate is stabilized at 85% for one and/or the other of the two markers. The seropositivity rate is 39% for the HBs antigen alone. A protocol to vaccinate infants less than one year is proposed.

Adolescent↗
PubMed1992

[Severe malaria attacks in adults in Cameroon: comparison of 2 therapeutic protocols using quinine via parenteral route].

Increasing frequency and severity of cerebral malaria have become a major problem in the area of Yaoundé (Cameroon, Central Africa). Based on recent findings in pharmacokinetic parameters in cerebral malaria, a quinine infusion regimen (8 mg of quinine base/kg of body weight over 1 h followed by 8 mg of base/kg over 7 h, then 8 mg/kg over 8 h 3 times daily for 3 days) was randomly allocated to 10 patients; 10 others received a more classical regimen currently used in Cameroon of 8 mg of base/kg over 8 h, 3 times daily for 3 days. In the loading dose group, there was a significant decrease in the duration of coma (48%), and the parasite clearance times were reduced by 33%. This regimen has been safe and effective: it is recommended in Yaoundé.

Adult↗
PubMed1992

[Feasibility of mosquito control using insecticide-impregnated bednets in rural areas of Cameroon].

The feasibility of using impregnated bednets in a malaria control strategy has been evaluated in a rural area of Cameroon. The benefit is well perceived by the population in terms of protection against nuisance but not in terms of prevention of the disease. The correct use of bednets is, however, unsatisfactory. The material should be adapted to the various sleeping accommodations, and efforts for education and information directed towards the potential users should be intensified.

Animals↗
PubMed1992

Proposals for a new therapeutic strategy for simple Plasmodium falciparum malaria attacks in Cameroon.

From simplified in vivo tests, authors set up a cartography of the sensitivity of Plasmodium falciparum to amino-4-quinolines in Cameroon; they also evaluated the clinical and parasitological efficacy of different therapeutic protocols which make use of amino-4-quinolines, quinine, mefloquine and halofantrine. All these drugs are administered orally. They recommend maintaining home medication with chloroquine at the dose of 25 mg/kg over 3 days, conserving quinine for use in the case of a possible failure. The use of most recent antimalarials can be proposed only as a last resort.

Administration, Oral↗
PubMed1987

[The last offensive of leprosy in the South Pacific Ocean: the epidemic on Rapa (1922-1950)].

The observations of leprosy outbreaks are exceptional and always situated in isolated countries. The authors give the example of Rapa, small island in French Polynesia, where an epidemic has occurred from 1922 to 1950. They made the study of the different parameters by retrospective methods and fieldwork. After an 11% incidence rate and an 68% prevalence rate, the outbreak seems today off. Now leprosy is endemosporadic.

Female↗