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Biomedical subjects

F J Louis

Publications and source records attributed to F J Louis.

63 records · Page 4Linked to original sources
PubMed1981

The mechanisms which affect the periodic cycle of Pacific Wuchereria bancrofti microfilariae.

1. Investigations were made of the effect of various procedures in raising or lowering the microfilaria count of Pacific type Wuchereria bancrofti in the peripheral blood. 2. Raising the body temperature in the early morning was followed by a moderate fall in the counts. Breathing increased oxygen, or reduced oxygen (hypoxia) or increased carbon dioxide, or the ingestion of sodium bicarbonate produced no consistent and significant change in the count. Ingestion of glucose (in one volunteer) was followed by a small rise in the count. Muscular exercise was followed by a fall in the count, which is interpreted as probably being a response to a lower concentration of oxygen in the venous blood returning to the lung. 3. It has not been possible to identify the physiological components on the circadian rhythm of the human body which entrain the cycle of these microfilariae. Attempts to obtain evidence incriminating the stimuli described above have been unsuccessful.

Adult↗
PubMed1978

Positive correlation of optical density at 650 nm. with lecithin/sphingomyelin ratios in amniotic fluid.

In this study, we have attempted to correlate optical density measurements of amniotic fluids with L/S ratios. We may conclude, with over a 98 per cent accuracy, that fluids having optical density readings of 0.15 and above, at 650 nm. will have an L/S ratio over 2.0. Fluids having optical density readings up to 0.05 will have L/S ratios of about 1.3. Finally, amniotic fluids having optical densities greater than 0.05 and less than 0.15 will have L/S ratios of approximately 1.5.

Amniotic Fluid↗
PubMedDate not supplied

High prevalence of anti-hepatitis C virus antibodies in a Cameroon rural forest area.

Sera of 807 people living in a rural forest area in southern Cameroon were tested by enzyme-linked immunosorbent assay; 101 (12.5%) gave positive results and were confirmed by line immunoassay. There was a highly significant difference between subjects aged over 40 years and those under 40 years, with the former having a much higher prevalence of antibodies. There were also significant differences between antibody prevalences among subjects aged > 40 years in the 3 ethnic groups studied--Baka Pygmies (6%), Fangs (30%) and Boulous (44%). Further studies are necessary to determine the reasons for these differences.

Adolescent↗
PubMedDate not supplied

[Use in Mozambique of WHO diagnostic strategies in HIV infection].

The lack of expensive equipment and well-trained laboratory technicians in developing countries makes it difficult to use standard methods (2 EIA confirmed by western blotting) to diagnose HIV infection. This led the WHO to develop simplified algorithms based on sequential screening tests, with no confirmation by immunoblotting. These algorithms were tested in the normal diagnosis conditions of a medical unit in Maputo, Mozambique. We tested 402 sera, collected with the consent of the patients concerned. The sera were first tested for HIV according to French regulations (2 EIA with western blot if at least one EIA was positive). This strategy identified 53 sera as positive for HIV1 and 1 serum as positive for HIV2. We then tested who algorithms, one for a predicted rate of prevalence < 10% and the other for a predicted rate of prevalence > 10%. Neither algorithm performed adequately for diagnostic purposes. Further evaluation with a panel of local sera is required to select the most suitable algorithm in terms of specificity and sensitivity, and algorithms should be throughly tested before inclusion in national AIDS control strategies.

AIDS Serodiagnosis↗
PubMedDate not supplied

[Viral hepatitis A: when a changing epidemiology implies a different prophylaxis].

Major progress has been made in the epidemiology and prophylaxis of hepatitis A virus (HAV) since it was first discovered in stool samples by MacCallum in 1973. Seven types of the virus have been described. Types 1, 2, 3 and 7 occur in humans and types 4, 5 and 6 in monkeys, but genotype is not correlated with antigenic response. Immunization with the HM175 viral strain or natural infection by any of the virus types gives protection against all types of HAV affecting humans. Serological tests detect all types of the virus and make it possible to carry out epidemiological studies anywhere in the world. HAV is common in very young children in developing countries. Most ten-year-old children are immune and have no clinical signs of the illness. HAV infection has become less common in developed countries due to improvements in hygiene. Less than 40% of people under the age of 30 have been immunized. Non-immune individuals have a high risk of developing clinical hepatitis if they become infected and the older the patient at the time of infection, the more severe the disease is likely to be. The introduction of HAV into groups in which the majority of individuals have not been immunized may result in major local outbreaks. Prophylaxis schemes are developed on the basis of epidemiology. Vaccination is not routinely recommended in developing countries, except for visitors to those countries. Vaccination is recommended for individuals in high-risk groups, such as health workers, cooks, sewer maintenance engineers and tourists, in developed countries. In countries with an intermediate level of risk (East Europe, the Middle East and Southeast Asia), there is a high level of HAV infection and a low level of immunization. Vaccination programs are likely to be of value in these countries.

Adult↗