Towards the WHO target of zero childhood tuberculosis deaths: an analysis of mortality in 13 locations in Africa and Asia

SETTING

Achieving the World Health Organization (WHO) target of zero paediatric tuberculosis (TB) deaths will require an understanding of the underlying risk factors for mortality.

OBJECTIVE

To identify risk factors for mortality and assess the impact of human immunodeficiency virus (HIV) testing during anti-tuberculosis treatment in children in 13 TB-HIV programmes run by Médecins Sans Frontières.

DESIGN

In a retrospective cohort study, we recorded mortality and analysed risk factors using descriptive statistics and logistic regression. Diagnosis was based on WHO algorithm and smear microscopy.

RESULTS

A total of 2451 children (mean age 5.2 years, SD 3.9) were treated for TB. Half (51.0%) lived in Asia, the remainder in sub-Saharan Africa; 56.0% had pulmonary TB; 6.4% were diagnosed using smear microscopy; 211 (8.6%) died. Of 1513 children tested for HIV, 935 (61.8%) were positive; 120 (12.8%) died compared with 30/578 (5.2%) HIV-negative children. Risk factors included being HIV-positive (OR 2.6, 95%CI 1.6-4.2), age <5 years (1.7, 95%CI 1.2-2.5) and having tuberculous meningitis (2.6, 95%CI 1.0-6.8). Risk was higher in African children of unknown HIV status than in those who were confirmed HIV-negative (1.9, 95%CI 1.1-3.3).

CONCLUSIONS

Strategies to eliminate childhood TB deaths should include addressing the high-risk groups identified in this study, enhanced TB prevention, universal HIV testing and the development of a rapid diagnostic test.

The reliability of a micro-computer administration of the MMPI

A computerized version of the MMPI was developed that incorporated both administration and scoring. This method was compared with the original manual form (N = 87). The results indicated that the test-retest reliability was high regardless of the method of administration and that similar results were obtained on the computer and on the manual forms of the MMPI.

Light-induced Enzyme Formation in a Chlorophyll-less Mutant of Euglena gracilis

A mutant strain, Y(9), of Euglena gracilis strain Z that is unable to produce protochlorophyll or chlorophyll has been isolated following treatment of wild type cells with nalidixic acid. Dark-grown cells of the mutant contain proplastids that show only limited ultrastructural development when placed in the light. Treatment of Y(9) cells with ultraviolet light brings about permanent cell bleaching with a target number similar to wild type Euglena, and with a slightly greater sensitivity to ultraviolet. Three enzymes of the reductive pentose phosphate cycle, fructose-1,6-diphosphate aldolase (class I), NADP-dependent glyceraldehyde-3-phosphate dehydrogenase, and 3-phosphoglycerate kinase, are detectable in dark-grown Y(9) cells at the low concentrations characteristic of dark-grown wild type cells, and increase substantially when these cells are exposed to light. The activity of ribulose-1,5-diphosphate carboxylase increases in the light to a lesser extent. Cytochrome 552, a carrier in the photosynthetic electron transport chain, is not present in light-grown cells of Y(9). The significance of this mutant for an understanding of the role of light in Euglena chloroplast development is discussed.

Absence of fluorescence quenching in a photosynthetic mutant of Euglena gracilis

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Isolation of mutants of Euglena gracilis with impaired photosynthesis

Four mutant strains of Euglena gracilis have been isolated after treatment of wild type cells with ultraviolet light or the chemical mutagen nitrosoguanidine. None of the mutants is capable of autotrophic growth or photosynthetic carbon dioxide fixation. The mutant strains contain normal amounts of the enzymes of the reductive pentose phosphate cycle and are qualitatively similar to the wild type in pigment composition, but are unable to carry out the Hill reaction (light induced reduction of 2,6-dichlorophenol indophenol). Isolated mutant plastids cannot photoreduce NADP with water as the electron donor but can carry out this reaction when the electron donating system is ascorbate and 2,6-dichlorophenol indophenol. Whole cells of the mutants show the light induced oxidation of cytochrome f by light reaction I but are unable to bring about cytochrome f reduction by light reaction II. The mutants appear to be blocked at or near light reaction II in the photosynthetic electron transport chain. The mutants may represent alterations of the chloroplast genome since the mutation isolation was carried out under conditions where chloroplast viability was severely impaired, but cell viability was unaffected.

Evidence for the participation of the reductive pentose phosphate cycle in photoreduction and the oxyhydrogen reaction

The assimilation of (14)C-sodium bicarbonate has been measured in Scenedesmus obliquus as 1) photosynthesis, 2) photoreduction (light dependent incorporation of carbon dioxide by hydrogen adapted cells under conditions where photosynthesis is inoperative), and 3) the oxyhydrogen reaction (dark assimilation of carbon dioxide by hydrogen adapted cells in an atmosphere of hydrogen and 1% oxygen). Degradation of the glucose formed in each of these reactions using the Leuconostoc technique establishes the participation of the reductive pentose phosphate cycle.

Regulation of Photosynthetic Capacity in Chlamydomonas mundana

A regulatory system has been described in the obligately phototrophic green alga Chlamydomonas mundana. Cells grown in acetate media are unable to fix carbon dioxide in the light but carry out a photoassimilation of acetate to carbohydrate: cells cultured with carbon dioxide as the sole source of cellular carbon carry out typical green plant photosynthesis. The control appears to take place at the level of the reductive pentose phosphate cycle. The presence of sodium acetate in the medium strongly inhibits formation of ribulose-1.5-diphosphate carboxylase, ribulose-5-phosphate kinase, and one of the 2 fructose-1,6-diphosphate aldolase activities of the cell. Ribose-5-phosphate isomerase is present in higher activity in autotrophic cells. Changes in the levels of triose phosphate dehydrogenase were also noted. The total pigment content of the cell and the photosynthetic electron transport reactions are not altered under different conditions of growth.