Errors in reported ages and dates in surveys of adult mortality: A record linkage study in Niakhar (Senegal).

Sibling survival histories are a major source of adult mortality estimates in countries with incomplete death registration. We evaluate age and date reporting errors in sibling histories collected during a validation study in the Niakhar Health and Demographic Surveillance System (Senegal). Participants were randomly assigned to either the Demographic and Health Survey questionnaire or a questionnaire incorporating an event history calendar, recall cues, and increased probing strategies. We linked 60-62 per cent of survey reports of siblings to the reference database using manual and probabilistic approaches. Both questionnaires showed high sensitivity (>96 per cent) and specificity (>97 per cent) in recording siblings' vital status. Respondents underestimated the age of living siblings, and age at and time since death of deceased siblings. These reporting errors introduced downward biases in mortality estimates. The revised questionnaire improved reporting of age of living siblings but not of age at or timing of deaths.

An alternative reaction for heme degradation catalyzed by the Escherichia coli O157:H7 ChuS protein: Release of hematinic acid, tripyrrole and Fe(III).

As part of the machinery to acquire, internalize and utilize heme as a source of iron from the host, some bacteria possess a canonical heme oxygenase, where heme plays the dual role of substrate and cofactor, the later catalyzing the cleavage of the heme moiety using O2 and electrons, and resulting in biliverdin, carbon monoxide and ferrous non-heme iron. We have previously reported that the Escherichia coli O157:H7 ChuS protein, which is not homologous to heme oxygenases, can bind and degrade heme in a reaction that releases carbon monoxide. Here, we have pursued a detailed characterization of such heme degradation reaction using stopped-flow UV-visible absorption spectrometry, the characterization of the intermediate species formed in such reaction by EPR spectroscopy and the identification of reaction products by NMR spectroscopy and Mass spectrometry. We show that hydrogen peroxide (in molar equivalent) is the key player in the degradation reaction, at variance to canonical heme oxygenases. While the initial intermediates of the reaction of ChuS with hydrogen peroxide (a ferrous keto π neutral radical and ferric verdoheme, both identified by EPR spectroscopy) are in common with heme oxygenases, a further and unprecedented reaction step, involving the cleavage of the porphyrin ring at adjacent meso-carbons, results in the release of hematinic acid (a monopyrrole moiety identified by NMR spectroscopy), a tripyrrole product (identified by Mass spectrometry) and non-heme iron in the ferric oxidation state (identified by EPR spectroscopy). Overall, the unprecedented reaction of E. coli O157:H7 ChuS provides evidence for a novel heme degradation activity in a Gram-negative bacterium.

Improving survey data on pregnancy-related deaths in low-and middle-income countries: a validation study in Senegal.

OBJECTIVE: In low- and middle-income countries (LMICs), siblings' survival histories (SSH) are often used to estimate maternal mortality, but SSH data on causes of death at reproductive ages have seldom been validated. We compared the accuracy of two SSH instruments: the standard questionnaire used during the demographic and health surveys (DHS) and the siblings' survival calendar (SSC), a new questionnaire designed to improve survey reports of deaths among women of reproductive ages. METHODS: We recruited 1189 respondents in a SSH survey in Niakhar, Senegal. Mortality records from a health and demographic surveillance system (HDSS) constituted the reference data set. Respondents were randomly assigned to an interview with the DHS or SSC questionnaires. A total of 164 respondents had a sister who died at reproductive ages over the past 15 years before the survey according to the HDSS. RESULTS: The DHS questionnaire led to selective omissions of deaths: DHS respondents were significantly more likely to report their sister's death if she had died of pregnancy-related causes than if she had died of other causes (96.4% vs. 70.9%, P < 0.007). Among reported deaths, both questionnaires had high sensitivity (>90%) in recording pregnancy-related deaths. But the DHS questionnaire had significantly lower specificity than the SSC (79.5% vs. 95.0%, P = 0.015). The DHS questionnaire overestimated the proportion of deaths due to pregnancy-related causes, whereas the SSC yielded unbiased estimates of this parameter. CONCLUSION: Statistical models informed by SSH data collected using the DHS questionnaire might exaggerate maternal mortality in Senegal and similar settings. A new questionnaire, the SSC, could permit better tracking progress towards the reduction in maternal mortality.