Sigmoid neural transfer function realized by percolation.

An experiment using the phenomenon of percolation has been conducted to demonstrate the implementation of neural functionality (summing and sigmoid transfer). A simple analog approximation to digital percolation is implemented. The device consists of a piece of amorphous silicon with stochastic bit-stream optical inputs, in which a current percolating from one end to the other defines the neuron output, also in the form of a stochastic bit stream. Preliminary experimental results are presented.

Seroprevalence of HIV infection among patients with pulmonary tuberculosis in Yaounde-Cameroun.

To determine the seroprevalence of infection with the human immunodeficiency virus (HIV) in pulmonary tuberculosis patients, we conducted an HIV serosurvey in 162 inpatients with pulmonary tuberculosis, in Yaoundé Cameroon. HIV seroprevalence in hospitalized pulmonary tuberculosis patients was found to be 9.9% as compared to the seroprevalence rate of 2.2% for Yaounde, the area from which the patients we studied came. No differences were observed in the clinical, radiological and bacteriological features between HIV seropositive and seronegative patients with pulmonary tuberculosis.

[Yellow fever epidemic in the extreme North of Cameroon in 1990: first yellow fever virus isolation in Cameroon]. / L'épidémie de fièvre jaune de l'extrême nord du Cameroun en 1990: premier isolement du virus amaril au Cameroun.

Some two years ago, suspicious cases of yellow fever (YF) were reported in northern Cameroon. A deadly epidemic broke out during the second half of the rainy season (from 15 September to 22 December 1990) with 180 known cases, of which 125 died. The real figures could have been between 5000 and 20,000 cases with between 500 and 1000 deaths. The affected area was within the yellow fever belt, which is situated around latitude 11 degrees North and 14 degrees East. In this mountainous area (altitude, about 800 m) the rural inhabitants are scattered, with a high density of 200,000 people per 1000 km2. Investigations began at the start of the dry season and a strain of yellow fever virus was isolated for the first time in Cameroon. A study of 107 serum samples (23 families in 11 villages) was carried out by immunofluorescence and ELISA, which showed 20% IgM carriers for yellow fever virus and nothing for the three other flaviviruses, although these were largely present; there were up to 98% crossed reactions in IgG with dengue 2 and West Nile strains. The under-10 age group represented 63% of the IgM carriers. An entomological study was carried out at the same time. It permitted the capture of Aedes aegypti, A. furcifer, A. luteocephalus and the identification of numerous potential larval sites, at times still in the productive phase of A. aegypti which is considered to be the principal vector.(ABSTRACT TRUNCATED AT 250 WORDS)

[Variola or a severe case of varicella? A case of human variola due to monkeypox virus in a child from the Cameroon]. / Variole ou varicelle grave? Un cas de variole humaine à monkeypox virus chez un enfant Camerounais.

Human monkeypox was suspected on clinical grounds in a seven years old child in Cameroon. The diagnosis was confirmed at the Center for Disease Control (CDC) in Atlanta, USA. This condition is rare. The present case is the third in Cameroon. An epidemiological and clinical survey carried out in the family and in the area where the patient lives, did not allow to identify other cases. The clinical evolution of the case was good as in those described elsewhere.

[The combined measles-yellow fever vaccination in African infants aged 6 to 10 months]. / Etude de la vaccination combinée rougeole-fièvre jaune chez l'enfant African âgé de 6 à 10 mois.

The compared tolerance and immunogenicity of vaccines against yellow fever and measles, separately administered or combined, have been evaluated in a group of 319 children from North Cameroon, aged 6-10 months. The clinical tolerance was excellent for both the isolated and the combined vaccines. The seroconversion level is higher after administration of the combined vaccine: 89.9% against 83.5% for measles, 95.8% against 92.6% for yellow fever, but these results are not significantly different. 30 days after vaccination, the antibody titers are higher with the combined vaccine: 215.3 against 156.5 for measles (non significant difference), 34 against 22.6 for yellow fever (highly significant difference). Whatever the vaccination method is, the antibody levels are protecting. It becomes then possible to include the combined vaccination against yellow fever and measles in the EPI of yellow fever endemic countries.

[In vitro virucidal activity of antiseptics and disinfectants. II. Simple dilution technic]. / Activité virucide in vitro des antiseptiques et désinfectants. II. Technique par dilution simple.

The simple dilution technique is based on termination of the tested agent's antiviral activity by sudden cold dilution (D). It can be used only if D less than or equal to 10(3) but is the most simple method. We used this technique to study ATS and demonstrate the strong virucidal activity of glutaraldehyde, inefficiency of chlorhexidine digluconate and questionable activity of povidone-iodine and noxythiolin.