763 research outputs found

    Opening dialogue and fostering collaboration: different ways of knowing in fisheries research

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    We set out to explore some of the impediments which hinder effective communication among fishers, fisheries researchers and managers using detailed ethnographic research amongst commercial handline fishers from two sites- one on the southern Cape coast and the other on the west coast of South Africa. Rather than assuming that the knowledge of fishers and scientists is inherently divergent and incompatible, we discuss an emerging relational approach to working with multiple ways of knowing and suggest that this approach might benefit future collaborative endeavours. Three major themes arising from the ethnographic fieldwork findings are explored: different classifications of species and things; bringing enumerative approaches into dialogue with relational approaches; and the challenge of articulating embodied ways of relating to fish and the sea. Although disconcertments arise when apparently incommensurable approaches are brought into dialogue, we suggest that working with multiple ways of knowing is both productive and indeed necessary in the current South African fisheries research and management contexts. The research findings and discussion on opening dialogue offered in this work suggest a need to rethink contemporary approaches to fisheries research in order to mobilise otherwise stagnant conversations, bringing different ways of knowing into productive conversation

    CR1 Knops blood group alleles are not associated with severe malaria in the Gambia

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    The Knops blood group antigen erythrocyte polymorphisms have been associated with reduced falciparum malaria-based in vitro rosette formation (putative malaria virulence factor). Having previously identified single-nucleotide polymorphisms (SNPs) in the human complement receptor 1 (CR1/CD35) gene underlying the Knops antithetical antigens Sl1/Sl2 and McC(a)/McC(b), we have now performed genotype comparisons to test associations between these two molecular variants and severe malaria in West African children living in the Gambia. While SNPs associated with Sl:2 and McC(b+) were equally distributed among malaria-infected children with severe malaria and control children not infected with malaria parasites, high allele frequencies for Sl 2 (0.800, 1,365/1,706) and McC(b) (0.385, 658/1706) were observed. Further, when compared to the Sl 1/McC(a) allele observed in all populations, the African Sl 2/McC(b) allele appears to have evolved as a result of positive selection (modified Nei-Gojobori test Ka-Ks/s.e.=1.77, P-value <0.05). Given the role of CR1 in host defense, our findings suggest that Sl 2 and McC(b) have arisen to confer a selective advantage against infectious disease that, in view of these case-control study data, was not solely Plasmodium falciparum malaria. Factors underlying the lack of association between Sl 2 and McC(b) with severe malaria may involve variation in CR1 expression levels

    HIV-1 Inhibits Phagocytosis and Inflammatory Cytokine Responses of Human Monocyte-Derived Macrophages to P. falciparum Infected Erythrocytes

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    HIV-1 infection increases the risk and severity of malaria by poorly defined mechanisms. We investigated the effect of HIV-1Ba-L infection of monocyte-derived macrophages (MDM) on phagocytosis of opsonised P. falciparum infected erythrocytes (IE) and subsequent proinflammatory cytokine secretion. Compared to mock-infected MDM, HIV-1 infection significantly inhibited phagocytosis of IE (median (IQR) (10 (0–28) versus (34 (27–108); IE internalised/100 MDM; p = 0.001) and decreased secretion of IL-6 (1,116 (352–3,387) versus 1,552 (889–6,331); pg/mL; p = 0.0078) and IL-1β (16 (7–21) versus 33 (27–65); pg/mL; p = 0.0078). Thus inadequate phagocytosis and cytokine production may contribute to impaired control of malaria in HIV-1 infected individuals

    Relevant Assay to Study the Adhesion of Plasmodium falciparum-Infected Erythrocytes to the Placental Epithelium

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    In placental malaria, Plasmodium falciparum-infected erythrocytes adhere to the apical plasma membrane of the placental epithelium, triggering an impairment of placental function detrimental to the fetus. The design of anti-adhesion intervention strategies requires a detailed understanding of the mechanisms involved. However, most adhesion assays lack in vivo relevance and are hardly quantitative. Here, we describe a flow cytometry-based adhesion assay that is fully relevant by using apical epithelial plasma membrane vesicles as the adhesion matrix, and being applicable to infected erythrocytes directly isolated from patients. Adhesion is measured both as the percentage of pathogens bound to epithelial membrane vesicles as well as the mean number of vesicles bound per infected erythrocytes. We show that adhesins alternative to those currently identified could be involved. This demonstrates the power of this assay to advance our understanding of epithelial adhesion of infected erythrocytes and in the design of intervention strategies

    Latest Miocene restriction of the Mediterranean Outflow Water:a perspective from the Gulf of Cádiz

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    The Mediterranean-Atlantic water mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during the closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins from the Gulf of Cádiz to the West Iberian margin to investigate MOW circulation during the latest Miocene. Seismic interpretation highlights a middle to upper Messinian seismic unit of transparent facies, whose base predates the onset of the Messinian salinity crisis (MSC). Its facies and distribution imply a predominantly hemipelagic environment along the Atlantic margins, suggesting an absence or intermittence of MOW preceding evaporite precipitation in the Mediterranean, simultaneous to progressive gateway restriction. The removal of MOW from the Mediterranean-Atlantic water mass exchange reorganized the Atlantic water masses and is correlated to a severe weakening of the Atlantic Meridional Overturning Circulation (AMOC) and a period of further cooling in the North Atlantic during the latest Miocene

    Effect of malaria on placental volume measured using three-dimensional ultrasound: a pilot study

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    Background: The presence of malaria parasites and histopathological changes in the placenta are associated with a reduction in birth weight, principally due to intrauterine growth restriction. The aim of this study was to examine the feasibility of studying early pregnancy placental volumes using three-dimensional (3D) ultrasound in a malaria endemic area, as a small volume in the second trimester may be an indicator of intra-uterine growth restriction and placental insufficiency. Methods: Placenta volumes were acquired using a portable ultrasound machine and a 3D ultrasound transducer and estimated using the Virtual Organ Computer-aided AnaLysis (VOCAL) image analysis software package. Intraobserver reliability and limits of agreement of the placenta volume measurements were calculated. Polynomial regression models for the mean and standard deviation as a function of gestational age for the placental volumes of uninfected women were created and tested. Based on these equations each measurement was converted into a z -score. The z-scores of the placental volumes of malaria infected and uninfected women were then compared. Results: Eighty-four women (uninfected = 65; infected = 19) with a posterior placenta delivered congenitally normal, live born, single babies. The mean placental volumes in the uninfected women were modeled to fit 5th, 10th, 50th, 90th and 95th centiles for 14-24 weeks’ gestation. Most placenta volumes in the infected women were below the 50th centile for gestational age; most of those with Plasmodium falciparum were below the 10th centile. The 95% intra-observer limits of agreement for first and second measurements were ± 37.0 mL and ± 25.4 mL at 30 degrees and 15 degrees rotation respectively. Conclusion: The new technique of 3D ultrasound volumetry of the placenta may be useful to improve our understanding of the pathophysiological constraints on foetal growth caused by malaria infection in early pregnancy

    Residential mobility during pregnancy in the north of England

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    <p>Abstract</p> <p>Background</p> <p>Many epidemiological studies assign exposure to an individual's residence at a single time point, such as birth or death. This approach makes no allowance for migration and may result in exposure error, leading to reduced study power and biased risk estimates. Pregnancy outcomes are less susceptible to this bias, however data from North American populations indicate that pregnant women are a highly mobile group. We assessed mobility in pregnant women in the north of England using data from the Northern Congenital Abnormality Survey (NorCAS).</p> <p>Methods</p> <p>Data were extracted from NorCAS for 1985 to 2003. Eligible cases had a gestational age at delivery of ≥ 24 weeks (a viable delivery) (n = 11 559). We assessed mobility between booking appointment (average gestational age 13 weeks) and delivery for pregnancies where the address at booking appointment and delivery were known. The impacts on mobility of maternal age and area-level socio-economic indicators were explored using standard descriptive statistics. A sensitivity analysis and a small validation exercise were undertaken to assess the impact of missing data on the estimate of mobility.</p> <p>Results</p> <p>Out of 7 919 eligible cases for whom addresses at booking and delivery were known, 705 (8.9% (95% CI 8.3 - 9.5)) moved between booking and delivery; the mean and median moving distance was 9.7 and 1.4 km respectively. Movers were significantly younger (25.4 versus 27.3 years, p < 0.01) and lived in more deprived areas (index of multiple deprivation score 38.3 versus 33.7, p < 0.01) than non movers.</p> <p>Conclusion</p> <p>Mobility in the north of England (9%) is considerably lower than that reported in North America and the only other study from the UK (23%). Consistent with other studies, mobility was related to maternal age and socio-economic status, and the majority of moves were over a relatively short distance. Although this population appears relatively stable, the mobility we have observed may still introduce misclassification or error into an exposure assessment relying solely on postcode at delivery, and migration should still therefore be considered a potential source of bias in future studies.</p

    An update of malaria infection and anaemia in adults in Buea, Cameroon

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    <p>Abstract</p> <p>Background</p> <p>Anaemia is caused by many factors in developing countries including malaria. We compared anaemia rates in patients with malaria parasitaemia to that of patients without malaria parasitaemia.</p> <p>Findings</p> <p>A cross-sectional study was carried out from November 2007 to July 2008 in health units in Buea, Cameroon. Adult patients with fever or history of fever were included in the study. Information on socio-demographic variables and other variables was collected using a questionnaire. Malaria parasitaemia status was determined by microscopy using Giemsa stained thick blood smears. Haemoglobin levels were determined by the microhaematocrit technique.</p> <p>The study population consisted of 250 adult patients with a mean age of 29.31 years (SD = 10.63) and 59.44% were females. 25.60% of the patients had malaria parasitaemia while 14.80% had anaemia (haemoglobin < 11 g/dl). Logistic regression revealed that those with malaria parasitaemia had more anaemia compared to those without malaria parasitaemia(OR = 4.33, 95%CI = 1.21-15.43, p = 0.02) after adjusting for age, sex, rural residence, socioeconomic status, use of antimalarials, use of insecticide treated nets(ITN) and white blood cell count.</p> <p>Conclusions</p> <p>In adult patients with fever in this setting, malaria parasitaemia contributes to anaemia and is of public health impact. Our results also provide a baseline prevalence for malaria parasitaemia in febrile adults in health units in this setting.</p

    Effectiveness evaluation of an integrated automatic termomechanic massage system (SMATH® system) in non-specific sub-acute and chronic low back pain - a randomized double-blinded controlled trial, comparing SMATH therapy versus sham therapy: study protocol for a randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Low back pain (LBP) is a major health problem in modern society, with 70-85% of the population experiencing LBP at some time in their lives. Each year, 5-10% of the workforce misses work due to LBP, most for less than 7 days. Almost 10% of all patients are at risk of developing chronic pain and disability. Little clinical evidence is available for the majority of treatments used in LBP therapy. However, moderate evidence exists for interdisciplinary rehabilitation, exercise, acupuncture, spinal manipulation, and cognitive behavioral therapy for subacute and chronic LBP. The SMATH<sup>® </sup>system (system for automatic thermomechanic massage in health) is a new medical device (MD) that combines basic principles of mechanical massage, thermotherapy, acupressure, infrared therapy, and moxibustion. SMATH<sup>® </sup>is suitable for automatic multidisciplinary treatment on patients with non-specific sub-acute and chronic LBP.</p> <p>Methods/design</p> <p>This paper describes the protocol for a double-blinded, sham-controlled, randomized, single-center short term clinical trial in patients with non-specific sub-acute and chronic LBP aged 18 to 70 years. The primary outcome will be the effectiveness of SMATH<sup>® </sup>versus sham therapy (medical device without active principles) determined by evaluating self perceived physical function with Roland Morris Disability Questionnaire (RMDQ) scores after 4 weeks of treatment (end of treatment). Major secondary outcome will be effectiveness of SMATH<sup>® </sup>determined by evaluating self perceived physical function comparing RMDQ scores between end of treatment and baseline. The trial part of the study will take 7 months while observational follow-up will take 11 months. The sample size will be 72 participants (36 for each arm). The project has been approved by the Ethical Committee of Cremona Hospital, Italy on 29 November 2010.</p> <p>Discussion</p> <p>Compared to other medical specialties, physical and rehabilitation medicine (PRM) has not yet received the deserved recognition from clinicians and researchers in the scientific community, especially for medical devices. The best way to change this disadvantage is through well-conducted clinical research in sham-controlled randomized trials. Sham treatment groups are essential for improving the level of evidence-based practice in PRM. The present trial will counter the general lack of evidence concerning medical devices used in LBP therapy.</p> <p>Trial Registration</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN08714168">ISRCTN08714168</a></p

    Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax – Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)

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    Recent reports of Plasmodium vivax infections, the most widely distributed species of human malaria, show that this parasite is evolving and adapting, becoming not only more aggressive but also more frequent in countries where it was not present in the past, becoming, therefore, a major source of concern. Thus, it is extremely important to perform new studies of its distribution in West and Central Africa, where there are few reports of its presence, due to the high prevalence of Duffy-negative individuals. The aim of this study was to investigate the presence of P. vivax in Angola and in Equatorial Guinea, using blood samples and mosquitoes. The results showed that P. vivax seems to be able to invade erythrocytes using receptors other than Duffy, and this new capacity is not exclusive to one strain of P. vivax, since we have found samples infected with two different strains: VK247 and classic. Additionally we demonstrated that the parasite has a greater distribution than previously thought, calling for a reevaluation of its worldwide distribution
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