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Biomedical subjects

J Ngu

Publications and source records attributed to J Ngu.

7 recordsLinked to original sources

Patterns of antibody levels to the 96 tR recombinant protein of Plasmodium falciparum in children over a six-month period.

Several Plasmodium falciparum asexual stage antigens have been reported as possible candidate antigens for vaccines against malaria. One such is the 96-kDa antigen. We used the 96 tR recombinant protein to determine the levels of antibodies to this protein over a 6-mo period in children 4 mo to 15 yr old, who make up the population at risk in Cameroon. The mean enzyme-linked immunosorbent assay (ELISA) on 83 children at the start of the study in June was 0.270, with 13% of these children having ELISA values considered to be positive (> or = 0.36). In the follow-up study in early December, the mean ELISA was 0.320 with 20% of the children having positive values. In the period between June and December, 85% of the children who returned for follow-up had had 1 or more attacks of malaria. The mean ELISA values of this latter group had increased from 0.235 in June to 0.318 in December, with 6% of the children in June having positive values compared with 18% in December. These findings reinforce our evidence from a previous study that reactivity to the 96-kDa antigen is related to adequate exposure or repeated infection.

Adolescent↗

Immunology of human immunodeficiency virus infection and the acquired immunodeficiency syndrome. An update.

Recent advances in the understanding of the pathogenesis of infection with human immunodeficiency virus (HIV) stems from the demonstration that the membrane glycoprotein, CD4, is the cellular receptor for HIV. This glycoprotein is found mainly on the surface of a major subpopulation of T lymphocytes and also on macrophages, natural killer cells, some B lymphocytes, and neuronal cells. Cells infected with HIV may be destroyed or have their normal function impaired. Host immune responses to HIV are poor and are not sustained. Neutralizing antibody often is not produced, or HIV may escape from normal immunosuppressive mechanisms through the process of rapid antigenic variation. Factors and markers that may be important in the outcome or that may predict progression of HIV infection are genetic (Gc type), environmental (nutritional status or intercurrent sexually transmitted diseases sustained by the host), and immunologic (rate of decline in number and impairment of function of CD4 lymphocytes and of decline in antibody titers to HIV core protein, p24). A recombinant vaccine will probably be developed for testing in future clinical trials.

Acquired Immunodeficiency Syndrome↗

Variation in delayed hypersensitivity in onchocerciasis.

Soluble antigen preparations were made from Onchocerca volvulus adults recovered from subcutaneous nodules, and from Necator americanus third-stage larvae. Intradermal skin tests were carried out on a total of 100 individuals clinically classified as having either the generalized form of onchocerciasis (86 cases, or the localized sowda form (14 cases). 91 of the people studied produced immediate reactions to the onchocercal antigen, but only those with sowda showed delayed reactions, though one person with generalized disease showed a doubtful delayed reaction. Reactions to N. americanus antigen, both immediate and delayed, were seen in both forms of the disease. The lack of delayed skin reaction in the generalized form of onchocerciasis is discussed, and a comparison is made with other diseases. Preliminary evidence for the existence of a true spectrum of clinical and immunological forms of onchocerciasis is suggested by one case in this study.

Adolescent↗

Juvenile Gaucher's disease with horizontal gaze palsy in three siblings.

Three children in a West African family had Gaucher's disease of juvenile onset (Type 3), and all showed an identical neurological disorder. The diagnosis was substantiated by histochemical demonstration of Gaucher cells in bone marrow, liver, and spleen, the finding of an excess of glucosyl ceramides in a liver extract, and a deficient activity of the enzyme beta-glucosidase in cultured skin fibroblasts. The neurological picture was characterised by myoclonic epilepsy, muscle wasting, hypotonia, pyramidal signs, some intellectual deterioration, and a striking disturbance of eye movements. The latter appears to result from specific involvement of the supranuclear pathways subserving lateral gaze. The distinctive features of this clinical syndrome are emphasised.

Age Factors↗

The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa.

In support of ongoing immunologic studies on immunity to Plasmodium falciparum, demographic, entomologic, parasitologic, and clinical studies were conducted in two Cameroonian villages located 3 km apart. Simbok (population = 907) has pools of water present year round that provide breeding sites for Anopheles gambiae, whereas Etoa (population = 485) has swampy areas that dry up annually in which A. funestus breed. Results showed that individuals in Simbok receive an estimated 1.9 and 1.2 infectious bites per night in the wet and dry season, respectively, whereas individuals in Etoa receive 2.4 and 0.4 infectious bites per night, respectively. Although transmission patterns differ, the rate of acquisition of immunity to malaria appears to be similar in both villages. A prevalence of 50-75% was found in children < 10 years old, variable levels in children 11-15 years old, and 31% in adults. Thus, as reported in other parts of Africa, individuals exposed to continuous transmission of P. falciparum slowly acquired significant, but not complete, immunity.

Adolescent↗