193 research outputs found

    Distribution of lipid biomarkers and carbon isotope fractionation in contrasting trophic environments of the South East Pacific

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    The distribution of lipid biomarkers and their stable carbon isotope composition was investigated on suspended particles from different contrasting trophic environments at six sites in the South East Pacific. High algal biomass with diatom-related lipids (24-methylcholesta-5,24(28)-dien-3β-ol, C<sub>25</sub> HBI alkenes, C<sub>16:4</sub> FA, C<sub>20:5</sub> FA) was characteristic in the upwelling zone, whereas haptophyte lipids (long-chain (C<sub>37</sub>-C<sub>39</sub>) unsaturated ketones) were proportionally most abundant in the nutrient-poor settings of the centre of the South Pacific Gyre and on its easter edge. The dinoflagellate–sterol, 4α-23,24-trimethylcholest-22(<i>E</i>)-en-3β-ol, was a minor contributor in all of the studied area and the cyanobacteria-hydrocarbon, C<sub>17</sub><i>n</i>-alkane, was at maximum in the high nutrient low chlorophyll regime of the subequatorial waters near the Marquesas archipelago. <br><br> The taxonomic and spatial variability of the relationships between carbon photosynthetic fractionation and environmental conditions for four specific algal taxa (diatoms, haptophytes, dinoflagellates and cyanobacteria) was also investigated. The carbon isotope fractionation factor (ε<sub>p</sub>) of the 24-methylcholesta-5,24(28)-dien-3β-ol diatom marker, varied over a range of 16% along the different trophic systems. In contrast, ε<sub>p</sub> of dinoflagellate, cyanobacteria and alkenone markers varied only by 7–10‰. The low fractionation factors and small variations between the different phytoplankton markers measured in the upwelling area likely reveals uniformly high specific growth rates within the four phytoplankton taxa, and/or that transport of inorganic carbon into phytoplankton cells may not only occur by diffusion but also by other carbon concentrating mechanisms (CCM). In contrast, in the oligotrophic zone, i.e. gyre and eastgyre, relatively high ε<sub>p</sub> values, especially for the diatom marker, indicate diffusive CO<sub>2</sub> uptake by the eukaryotic phytoplankton. At these nutrient-poor sites, the lower ε<sub>p</sub> values for haptophytes, dinoflagellates and cyanobacteria indicate higher growth rates or major differences on the carbon uptake mechanisms compared to diatoms

    Meridional transport of dissolved inorganic carbon in the South Atlantic Ocean

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    The meridional oceanic transports of dissolved inorganic carbon and oxygen were calculated using six transoceanic sections occupied in the South Atlantic between 11 degrees S and 30 degrees S. The total dissolved inorganic carbon (TCO2) data were interpolated onto conductivity-temperature-depth data to obtain a high-resolution data set, and Ekman, depth-dependent and depth-independent components of the transport were estimated. Uncertainties in the depth-independent velocity distribution were reduced using an inverse model. The inorganic carbon transport between 11 degrees S and 30 degrees S was southward, decreased slightly toward the south, and was -2150 +/- 200 kmol s(-1) (-0.81 +/- 0.08 Gt C yr(-1)) at 20 degrees S. This estimate includes the contribution of net mass transport required to balance the salt transport through Bering Strait. Anthropogenic CO2 concentrations were estimated for the sections. The meridional transport of anthropogenic CO2 was northward, increased toward the north, and was 430 kmol s(-1) (0.16 Gt C yr(-1)) at 20 degrees S. The calculations imply net southward inorganic carbon transport of 2580 kmol s(-1) (1 Gt C yr(-1)) during preindustrial times. The slight contemporary convergence of inorganic carbon between 10 degrees S and 30 degrees S is balanced by storage of anthropogenic CO2 and a sea-to-air flux implying little local divergence of the organic carbon transport. During the preindustrial era, there was significant regional convergence of both inorganic carbon and oxygen, consistent with a sea-to-air gas flux driven by warming. The northward transport of anthropogenic CO2 carried by the meridional overturning circulation represents an important source for anthropogenic CO2 currently being stored within the North Atlantic Ocean

    Evidence and Policy in Aid-Dependent Settings

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    This chapter examines how the political dynamics of aid relationships can affect the use of evidence within health policymaking. Empirical examples from Cambodia, Ethiopia and Ghana illustrate how relationships between national governments and donor agencies influence the ways in which evidence is generated, selected, or utilised to inform policymaking. We particularly consider how relationships with donors influence the underlying systems and processes of evidence use. We find a number of issues affecting which bodies or forms of evidence are taken to be policy relevant, including: levels of local technical capacity to utilise or synthesise evidence; differing stakeholder framing of issues; and the influence of non-state actors on sector-wide systems of agenda setting. The chapter also reflects on some of the key governance implications of these arrangements in which global actors promote forms of evidence use – often under a banner of technical efficiency – with limited consideration for local representation or accountability

    Management of hepatic epithelioid haemangio-endothelioma in children: what option?

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    Hepatic epithelioid haemangio-endothelioma (HEHE) is an endothelium-derived tumour of low-to-medium grade malignancy. It is predominantly seen in adults and is unresponsive to chemotherapy. Liver transplantation is an accepted indication when the tumour is unresectable. Hepatic epithelioid haemangio-endothelioma is very rare in children and results after transplantation are not reported. The aim of this study is to review the experience of three European centres in the management of HEHE in children. A retrospective review of all paediatric patients with HEHE managed in three European centres is presented. Five children were identified. Four had unresectable tumours. The first had successful resection followed by chemotherapy and is alive, without disease 3 years after diagnosis. One child died of sepsis and one of tumour recurrence in the graft and lungs 2 and 5 months, respectively, after transplant. Two children who had progressive disease with ifosfamide-based chemotherapy have had a reduction in clinical symptoms and stabilisation of disease up to 18 and 24 months after the use of platinum-based chemotherapy. HEHE seems more aggressive in children than reported in adults and the curative role of transplantation must be questioned. Ifosfamide-based chemotherapy was not effective. Further studies are necessary to confirm if HEHE progression in children may be influenced by platinum-based chemotherapy

    Emerging Disease Burdens and the Poor in Cities of the Developing World

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    Patterns of future urban growth, combined with advances in the treatment of traditional scourges of communicable diseases, will cause a shift in the burden of disease toward category 2 (noncommunicable) and 3 (injury) conditions over the next 30 years. Communicable diseases, particularly HIV/AIDs, will continue to be the most important killers among the poor. However, new risks will emerge for several reasons. First, the marked sprawl of cities in the developing world will make access to care more difficult. Second, increasing motor vehicles and the likelihood of inadequate infrastructure will make air pollution and accidents in road traffic more common than in the past. Third, impoverished urban populations have already shown a propensity toward undernourishment, and its obverse, obesity, is already emerging as a major risk. Also, the large projected increase in slums suggests that violence and homicide will become a more important burden of health, and very large hazards will be created by fire-prone, insubstantial dwellings that will house nearly two billion people by 2030. In addition, decentralized governance will exacerbate the tensions and discontinuities that have plagued the management of health issues on the urban fringe over the past decade. Accordingly, public health agencies will need to adjust to the regional and country-specific factors to address the changing profile of risk. This analysis suggests that four factors – levels of poverty, speed of city growth, sprawl in cities, and degree of decentralization – will have importance in shaping health strategies. These factors vary in pace and intensity by region, suggesting that health care strategies for Category II and III conditions will need to be differentiated by region of the world. Also, interventions will have to rely increasingly on actors outside the ranks of public health specialists

    Measles outbreaks in displaced populations: a review of transmission, morbidity and mortality associated factors

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    <p>Abstract</p> <p>Background</p> <p>Measles is a highly contagious infectious disease with a significant public health impact especially among displaced populations due to their characteristic mass population displacement, high population density in camps and low measles vaccination coverage among children. While the fatality rate in stable populations is generally around 2%, evidence shows that it is usually high among populations displaced by disasters. In recent years, refugees and internally displaced persons have been increasing. Our study aims to define the epidemiological characteristics and risk factors associated with measles outbreaks in displaced populations.</p> <p>Methods</p> <p>We reviewed literature in the PubMed database, and selected articles for our analysis that quantitatively described measles outbreaks.</p> <p>Results</p> <p>A total of nine articles describing 11 measles outbreak studies were selected. The outbreaks occurred between 1979 and 2005 in Asia and Africa, mostly during post-conflict situations. Seven of eight outbreaks were associated with poor vaccination status (vaccination coverage; 17-57%), while one was predominantly due to one-dose vaccine coverage. The age of cases ranged from 1 month to 39 years. Children aged 6 months to 5 years were the most common target group for vaccination; however, 1622 cases (51.0% of the total cases) were older than 5 years of age. Higher case-fatality rates (>5%) were reported for five outbreaks. Consistent factors associated with measles transmission, morbidity and mortality were vaccination status, living conditions, movements of refugees, nutritional status and effectiveness of control measures including vaccination campaigns, surveillance and security situations in affected zones. No fatalities were reported in two outbreaks during which a combination of active and passive surveillance was employed.</p> <p>Conclusion</p> <p>Measles patterns have varied over time among populations displaced by natural and man-made disasters. Appropriate risk assessment and surveillance strategies are essential approaches for reducing morbidity and mortality due to measles. Learning from past experiences of measles outbreaks in displaced populations is important for designing future strategies for measles control in such situations.</p

    Consequences of Cold-Ischemia Time on Primary Nonfunction and Patient and Graft Survival in Liver Transplantation: A Meta-Analysis

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    Introduction: The ability to preserve organs prior to transplant is essential to the organ allocation process. Objective: The purpose of this study is to describe the functional relationship between cold-ischemia time (CIT) and primary nonfunction (PNF), patient and graft survival in liver transplant. Methods: To identify relevant articles Medline, EMBASE and the Cochrane database, including the non-English literature identified in these databases, was searched from 1966 to April 2008. Two independent reviewers screened and extracted the data. CIT was analyzed both as a continuous variable and stratified by clinically relevant intervals. Nondichotomous variables were weighted by sample size. Percent variables were weighted by the inverse of the binomial variance. Results: Twenty-six studies met criteria. Functionally, PNF%=-6.678281+0.9134701*CIT Mean+0.1250879*(CIT Mean-9.89535) 2 - 0.0067663*(CIT Mean-9.89535) 3, r2=.625, p<.0001. Mean patient survival: 93 % (1 month), 88 % (3 months), 83 % (6 months) and 83 % (12 months). Mean graft survival: 85.9 % (1 month), 80.5 % (3 months), 78.1 % (6 months) and 76.8 % (12 months). Maximum patient and graft survival occurred with CITs between 7.5-12.5 hrs at each survival interval. PNF was also significantly correlated with ICU time, % first time grafts and % immunologic mismatches. Conclusion: The results of this work imply that CIT may be the most important pre-transplant information needed in the decision to accept an organ. © 2008 Stahl et al

    Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: a systematic review and modelling study.

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    BACKGROUND: We have previously estimated that respiratory syncytial virus (RSV) was associated with 22% of all episodes of (severe) acute lower respiratory infection (ALRI) resulting in 55 000 to 199 000 deaths in children younger than 5 years in 2005. In the past 5 years, major research activity on RSV has yielded substantial new data from developing countries. With a considerably expanded dataset from a large international collaboration, we aimed to estimate the global incidence, hospital admission rate, and mortality from RSV-ALRI episodes in young children in 2015. METHODS: We estimated the incidence and hospital admission rate of RSV-associated ALRI (RSV-ALRI) in children younger than 5 years stratified by age and World Bank income regions from a systematic review of studies published between Jan 1, 1995, and Dec 31, 2016, and unpublished data from 76 high quality population-based studies. We estimated the RSV-ALRI incidence for 132 developing countries using a risk factor-based model and 2015 population estimates. We estimated the in-hospital RSV-ALRI mortality by combining in-hospital case fatality ratios with hospital admission estimates from hospital-based (published and unpublished) studies. We also estimated overall RSV-ALRI mortality by identifying studies reporting monthly data for ALRI mortality in the community and RSV activity. FINDINGS: We estimated that globally in 2015, 33·1 million (uncertainty range [UR] 21·6-50·3) episodes of RSV-ALRI, resulted in about 3·2 million (2·7-3·8) hospital admissions, and 59 600 (48 000-74 500) in-hospital deaths in children younger than 5 years. In children younger than 6 months, 1·4 million (UR 1·2-1·7) hospital admissions, and 27 300 (UR 20 700-36 200) in-hospital deaths were due to RSV-ALRI. We also estimated that the overall RSV-ALRI mortality could be as high as 118 200 (UR 94 600-149 400). Incidence and mortality varied substantially from year to year in any given population. INTERPRETATION: Globally, RSV is a common cause of childhood ALRI and a major cause of hospital admissions in young children, resulting in a substantial burden on health-care services. About 45% of hospital admissions and in-hospital deaths due to RSV-ALRI occur in children younger than 6 months. An effective maternal RSV vaccine or monoclonal antibody could have a substantial effect on disease burden in this age group. FUNDING: The Bill & Melinda Gates Foundation
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