High prevalence of urinary schistosomiasis in a desert population: results from an exploratory study around the ounianga lakes in Chad

Background: Researching a water-borne disease in the middle of the Sahara desert might not seem the most relevant concern. However, nomadic Sahelian pastoralist's health concerns regarding their livestock and anecdotal reports about trematode infections of Fasciola spp and Schistosoma spp in desert-raised animals justified an exploratory study focusing on the lakes of Ounianga in Northern Chad. The aim was to test whether trematode parasites such as Schistosoma spp occur in human populations living around the Sahara desert lakes of Ounianga Kebir and Ounianga Saker in northern Chad. Methods: The study comprised of three components. First, a cross sectional survey based on a random sample drawn from the population to detect infections with S. haematobium and S. mansoni ; second, focus group discussions exploring disease priorities, access to health and health seeking behaviour; and third, searching water contact sites for intermediate host snails. Samples of trematode parasites and snails were confirmed on species level by molecular genetics methods. Results: Among 258 participants, the overall S. haematobium prevalence using urine filtration was 39.1% (95% CI 33.2% - 45.1%), with 51.5% of the infected suffering from heavy infection. The intermediate host snail of S. haematobium ( Bulinus truncatus ) occurred at water sites near both study villages, revealing the potential for local transmission. Although a positive S. mansoni POC-CCA test result was obtained from 15.2% (10.6%-19.7%) of the samples no intermediate host snails of S. mansoni were found, and the relevance of S. mansoni remains uncertain. Qualitative findings underline the importance of morbidity caused by urinary schistosomiasis, and the lack of access to diagnostics and treatment as a major health concern. Conclusion: This research revealed a high prevalence of urinary schistosomiasis in the population living around the lakes of Ounianga in the Sahara, a UNESCO world heritage site in Chad. Despite the high public health importance of the associated morbidity expressed by the population there is no access to diagnostics and treatment. Further research is needed to develop and test a context adapted intervention

3D printed facial laser scans for the production of localised radiotherapy treatment masks

This study investigates the use of 3D printing for patients that require localised radiotherapy treatment to the face. The current process involves producing a lead mask in order to protect the healthy tissue from the effects of the radiotherapy. The mask is produced by applying a thermoplastic sheet to the patient’s face and allowing to set hard. This can then be used as a mould to create a plaster impression of the patient’s face. A sheet of lead is then hammered on to the plaster to create a bespoke fitted face mask. This process can be distressing for patients and can be problematic when the patient is required to remain motionless for a prolonged time while the thermoplastic sets. In this study, a 1:1 scale 3D print of a patient’s face was generated using a laser scanner. The lead was hammered directly on to the surface of the 3D print in order to create a bespoke fitted treatment mask. This eliminated the thermoplastic moulding stage and significantly reduced the time needed for the patient to be in clinic. The higher definition impression of the face resulted in a more accurate, better fitting treatment mask

Small Sample Properties of Forecasts from Autoregressive Models under Structural Breaks

Autoregressive models are used routinely in forecasting and often lead to better performance than more complicated models. However, empirical evidence is also suggesting that the autoregressive representations of many macroeconomic and financial time series are likely to be subject to structural breaks. This paper develops a theoretical framework for the analysis of small-sample properties of forecasts from general autoregressive models under a structural break. Our approach is quite general and allows for unit roots both pre- and post-break. We derive finite-sample results for the mean squared forecast error of one-step-ahead forecasts, both conditionally and unconditionally and present numerical results for different types of break specifications. Implication of breaks for the determination of the optimal window size are also discussed

Forecasting U.S. Tourist arrivals using optimal Singular Spectrum Analysis

This study examines the potential advantages of using Singular Spectrum Analysis (SSA) for forecasting tourism demand. To do this it examines the performance of SSA forecasts using monthly data for tourist arrivals into the United States over the period 1996 to 2012. The SSA forecasts are compared to those from a range of other forecasting approaches previously used to forecast tourism demand. These include ARIMA, exponential smoothing and neural networks. The results presented show that the SSA approach produces forecasts which perform (statistically) significantly better than the alternative methods in forecasting total tourist arrivals into the U.S. Forecasts using the SSA approach are also shown to offer a significantly better forecasting performance for arrivals into the U.S. from individual source countries. Of the alternative forecasting approaches exponential smoothing and feed-forward neural networks in particular were found to perform poorly. The key conclusion is that Singular Spectrum Analysis (SSA) offers significant advantages in forecasting tourist arrivals into the US and is worthy of consideration for other forecasting studies of tourism demand

Decoupled diversity dynamics in green and brown webs during primary succession in a salt marsh

1.Terrestrial ecosystems are characterised by a strong functional connection between the green (plant-herbivore-based) and brown (detritus-detritivore-based) parts of the food web, which both develop over successional time. However, the interlinked changes in green and brown food web diversity patterns in relation to key ecosystem processes are rarely studied. 2.Here, we demonstrate changes in species richness, diversity and evenness over a wide range of invertebrate green and brown trophic groups during 100 years of primary succession in a salt marsh ecosystem, using a well-calibrated chronosequence. 3.We contrast two hypotheses on the relationship between green and brown food web diversity across succession: i) ‘coupled diversity hypothesis’, which predicts that all trophic groups covary similarly with the main drivers of successional ecosystem assembly versus ii) the ‘decoupled diversity hypothesis’, where green and brown trophic groups diversity respond to different drivers during succession. 4.We found that, while species richness for plants and invertebrate herbivores (green web groups) both peaked at intermediate productivity and successional age, the diversity of macro-detritivores, microarthropod microbivores and secondary consumers (brown web groups) continuously increased towards the latest successional stages. These results suggest that green web trophic groups are mainly driven by vegetation parameters, such as the amount of bare soil, vegetation biomass production, and vegetation height, while brown web trophic groups are mostly driven by the production and standing stock of dead organic material and soil development. 5.Our results show that plant diversity cannot simply be used as a proxy for the diversity of all other species groups that drive ecosystem functioning, as brown and green diversity components in our ecosystem responded differently to successional gradients

Co-evolution of NK receptors and HLA ligands in humans is driven by reproduction.

Allogeneic individuals co-exist during pregnancy in eutherian mammals. Maternal and fetal cells intermingle at the site of placental attachment in the uterus, where the arteries are remodeled to supply the fetus with oxygen and nutrients. This access by placental cells to the maternal supply line determines the growth and birth weight of the baby and is subject to stabilizing selection. Invading placental trophoblast cells express human leukocyte antigen class I ligands (HLA-E, HLA-G, and HLA-C) for receptors on maternal uterine natural killer (NK) and myelomonocytic cells, CD94/NKG2, leukocyte immunoglobulin-like receptor (LILR), and killer immunoglobulin receptor (KIR). Of these, only the KIR/HLA-C system is highly polymorphic. Different combinations of maternal KIR and fetal HLA-C variants are correlated with low birth weight and pre-eclampsia or high birth weight and obstructed labor, the two extremes of the obstetric dilemma. This situation has arisen because of the evolution of bipedalism and subsequently, in the last million years, larger brains. At this point, the human system began to reach a balance between KIR A and KIR B haplotypes and C1 and C2 epitopes of HLA-C alleles that reflects a functional compromise between the competing demands of immunity and reproduction.We are grateful for financial support from Centre for Trophoblast Research, University of Cambridge, King's College, Cambridge, and the Wellcome Trust.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/imr.1232

Reverse and Conventional Chemical Ecology Approaches for the Development of Oviposition Attractants for Culex Mosquitoes

Synthetic mosquito oviposition attractants are sorely needed for surveillance and control programs for Culex species, which are major vectors of pathogens causing various human diseases, including filariasis, encephalitis, and West Nile encephalomyelitis. We employed novel and conventional chemical ecology approaches to identify potential attractants, which were demonstrated in field tests to be effective for monitoring populations of Cx. p. quinquefasciatus in human dwellings. Immunohistochemistry studies showed that an odorant-binding protein from this species, CquiOBP1, is expressed in trichoid sensilla on the antennae, including short, sharp-tipped trichoid sensilla type, which house an olfactory receptor neuron sensitive to a previously identified mosquito oviposition pheromone (MOP), 6-acetoxy-5-hexadecanolide. CquiOBP1 exists in monomeric and dimeric forms. Monomeric CquiOBP1 bound MOP in a pH-dependent manner, with a change in secondary structure apparently related to the loss of binding at low pH. The pheromone antipode showed higher affinity than the natural stereoisomer. By using both CquiOBP1 as a molecular target in binding assays and gas chromatography-electroantennographic detection (GC-EAD), we identified nonanal, trimethylamine (TMA), and skatole as test compounds. Extensive field evaluations in Recife, Brazil, a region with high populations of Cx. p. quinquefasciatus, showed that a combination of TMA (0.9 µg/l) and nonanal (0.15 ng/µl) is equivalent in attraction to the currently used infusion-based lure, and superior in that the offensive smell of infusions was eliminated in the newly developed synthetic mixture

A homodimeric complex of HLA-G on normal trophoblast cells modulates antigen-presenting cells via LILRB1

In healthy individuals, the non-classical MHC molecule HLA-G is only expressed on fetal trophoblast cells that invade the decidua during placentation. We show that a significant proportion of HLA-G at the surface of normal human trophoblast cells is present as a disulphide-linked homodimer of the conventional β2m-associated HLA-I complex. HLA-G is a ligand for leukocyte immunoglobulin-like receptors (LILR), which bind much more efficiently to dimeric HLA-G than to conventional HLA-I molecules. We find that a LILRB1-Fc fusion protein preferentially binds the dimeric form of HLA-G on trophoblast cells. We detect LILRB1 expression on decidual myelomonocytic cells; therefore, trophoblast HLA-G may modulate the function of these cells. Co-culture with HLA-G+ cells does not inhibit monocyte-derived dendritic cell up-regulation of HLA-DR and costimulatory molecules on maturation, but did increase production of IL-6 and IL-10. Furthermore, proliferation of allogeneic lymphocytes was inhibited by HLA-G binding to LILRB1/2 on responding antigen-presenting cells (APC). As HLA-G is the only HLA-I molecule that forms β2m-associated dimers with increased avidity for LILRB1, this interaction could represent a placental-specific signal to decidual APC. We suggest that the placenta is modulating maternal immune responses locally in the uterus through HLA-G, a trophoblast-specific, monomorphic signal present in almost every pregnancy