Performance of the integrated management of childhood illness algorithm for diagnosis of HIV-1 infection among African infants.

OBJECTIVES: Early infant HIV-1 diagnosis and treatment substantially improve survival. Where virologic HIV-1 testing is unavailable, integrated management of childhood illness (IMCI) clinical algorithms may be used for infant HIV-1 screening. We evaluated the performance of the 2008 WHO IMCI HIV algorithm in a cohort of HIV-exposed Kenyan infants. METHODS: From 1999 to 2003, 444 infants had monthly clinical assessments and quarterly virologic HIV-1 testing. Using archived clinical data, IMCI sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using virologic testing as a gold standard. Linear regression and survival analyses were used to determine the effect of age on IMCI performance and timing of diagnosis. RESULTS: Overall IMCI sensitivity, specificity, PPV, and NPV value were 58, 87, 52, and 90%, respectively. Sensitivity (1.4%) and PPV (14%) were lowest at 1 month of age, when 81% of HIV infections already had occurred. Sensitivity increased with age (P < 0.0001), but remained low throughout infancy (range 1.4-35%). Specificity (range 97-100%) was high at each time point and was not associated with age. Fifty-eight percent of HIV-1-infected infants (50 of 86) were eventually diagnosed by IMCI, and use of IMCI was estimated to delay diagnosis in HIV-infected infants by a median of 5.9 months (P < 0.0001). CONCLUSION: IMCI had low sensitivity during the first month of life, when the majority of HIV-1 infections had already occurred and initiation of treatment is most critical. Although sensitivity increased with age, the substantial delay in HIV-1 diagnosis using IMCI limits its utility in early infant HIV-1 diagnosis.

Optimization of differential display polymerase chain reaction as a bioindicator for the cladoceran Daphnia magna.

Research on toxicant-responsive genes is providing new and important bioindicators for environmental biologists. Identifying genes whose expression is modulated by toxicant exposure provides important clues into the mechanisms underlying toxicity. In addition, toxicant-responsive genes can be developed as molecular end points that are likely to be sensitive tools for environmental assessment. Differential display polymerase chain reaction (ddPCR) is a useful approach for screening and analyzing the expression of genes. A ddPCR protocol was optimized to investigate gene expression in the cladoceran Daphnia magna. The modified protocol requires submicrogram quantities of total RNA (from <10 animals) and utilizes a sensitive fluorescent tagging system. By reverse-transcribing total RNA with arbitrary 18-nucleotide primers and PCR-amplifying the cDNA using the same arbitrary primers under low-stringency conditions, reproducible and consistent ddPCR profiles were generated. Minimal variability was introduced by reaction differences or biological variability. A trial stress (starvation) was found to generate modest differences in the ddPCR profiles. This technique promises to significantly advance knowledge regarding gene expression during toxicant insult. Furthermore, this represents the first step in the development of a novel gene fingerprinting technique that can be applied to any compound and organism of interest.

Cadmium-induced production of a metallothioneinlike protein in Tubifex tubifex (Oligochaeta) and Chironomus riparius (Diptera): correlation with reproduction and growth.

Laboratory-cultured Chironomus riparius and Tubifex tubifex were exposed to sediments artificially enriched with a range of cadmium (Cd) concentrations. Both species accumulated Cd in a concentration-dependent manner. The concentration of a metallothioneinlike protein (MTLP), as measured by a mercury saturation assay, increased with increasing Cd exposure. After reaching a threshold of Cd exposure, the whole-body endpoints of reproductive output in T. tubifex and growth in C. riparius declined significantly. The threshold effect concentrations for T. tubifex and C. riparius were 2.68 and 0.134 micromol Cd/g dry sediment, respectively. Metallothioneinlike protein and Cd tissue concentrations were more sensitive indicators of exposure than the whole-body endpoints. For T. tubifex, the concentrations of MTLP and tissue Cd were significantly elevated above control levels after exposure to the 0.67 micromol Cd/g dry sediment treatment. In C. riparius, MTLP concentration and tissue Cd concentration were both significantly elevated above control levels after exposure to the 3.8 x 10(-3) micromol Cd/g dry sediment treatment. Analysis of these data suggests that MTLP and tissue Cd concentrations are sensitive subcellular endpoints, which can be used to predict exposure to and the effects of metals at the individual or population level.