Natural ventilation for the prevention of airborne contagion.

BACKGROUND: Institutional transmission of airborne infections such as tuberculosis (TB) is an important public health problem, especially in resource-limited settings where protective measures such as negative-pressure isolation rooms are difficult to implement. Natural ventilation may offer a low-cost alternative. Our objective was to investigate the rates, determinants, and effects of natural ventilation in health care settings. METHODS AND FINDINGS: The study was carried out in eight hospitals in Lima, Peru; five were hospitals of "old-fashioned" design built pre-1950, and three of "modern" design, built 1970-1990. In these hospitals 70 naturally ventilated clinical rooms where infectious patients are likely to be encountered were studied. These included respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. These rooms were compared with 12 mechanically ventilated negative-pressure respiratory isolation rooms built post-2000. Ventilation was measured using a carbon dioxide tracer gas technique in 368 experiments. Architectural and environmental variables were measured. For each experiment, infection risk was estimated for TB exposure using the Wells-Riley model of airborne infection. We found that opening windows and doors provided median ventilation of 28 air changes/hour (ACH), more than double that of mechanically ventilated negative-pressure rooms ventilated at the 12 ACH recommended for high-risk areas, and 18 times that with windows and doors closed (p < 0.001). Facilities built more than 50 years ago, characterised by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms (40 versus 17 ACH; p < 0.001). Even within the lowest quartile of wind speeds, natural ventilation exceeded mechanical (p < 0.001). The Wells-Riley airborne infection model predicted that in mechanically ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients of infectiousness characterised in a well-documented outbreak. This infection rate compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open. CONCLUSIONS: Opening windows and doors maximises natural ventilation so that the risk of airborne contagion is much lower than with costly, maintenance-requiring mechanical ventilation systems. Old-fashioned clinical areas with high ceilings and large windows provide greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion

Exploring the Effect of G6PC2 Single Nucleotide Polymorphisms on Enzyme Activity and Human Health

G6PC2 encodes a glucose-6-phosphatase catalytic subunit that is highly expressed in pancreatic islet beta cells. Genome wide association studies (GWAS) have shown that single nucleotide polymorphisms (SNPs) in the G6PC2 gene are associated with variations in fasting blood glucose (FBG), a parameter linked with risk for type 2 diabetes (T2D). Studies in mice have complemented these GWAS data by showing that deletion of G6pc2 abolishes islet glucose-6-phosphatase activity and lowers FBG. We hypothesize that G6pc2 forms a substrate cycle with glucokinase that determines the sensitivity of glucose-stimulated insulin secretion (GSIS) to glucose. In support of this hypothesis we have previously shown that deletion of G6pc2 enhances GSIS at sub-maximal glucose concentrations and abolishes glucose cycling in isolated islets. More recently we have demonstrated that deletion of G6pc2 enhances glycolysis in isolated mouse islets, and that high rates of glucose cycling are also detected in human islets. Our broad hypothesis is that the results of these studies will strongly suggest that G6PC2 inhibition should be considered as a novel therapeutic strategy for lowering FBG and thereby preventing T2D. To extend these observations we have developed a novel intact cell assay for G6PC2 activity. This assay relies on the observation that CREB and ChREBP bound to the rat G6PC1 promoter are highly glucose responsive in the rat islet-derived 832/13 cell line and the fact that endogenous G6PC2 is absent. In the presence of catalytically-dead G6PC2, glucose stimulates G6PC1-luciferase fusion gene expression. However, this induction is blunted in the presence of wild type G6PC2. We are using this assay to determine the effect of non-synonymous G6PC2 SNPs on G6PC2 activity and then examining the association between SNPs that markedly affect G6PC2 activity with their effects on human health as assessed using Vanderbilt’s BioVU biobank. These data will reveal whether SNPs in G6PC2 are associated with only altered FBG or whether G6PC2 affects other aspects of human health

Global mantle flow retrodictions for the early Cenozoic using an adjoint method: Evolving dynamic topographies, deep mantle structures, flow trajectories and sublithospheric stresses

During the Cenozoic, the Earth experienced multiple first-order geological events that are likely mantle flow related. These include the termination of large-scale marine inundation in North America in the Palaeocene, the late Tertiary rise of Africa relative to other continents and the long-wavelength tilting of Australia since the late Cretaceous, which occurred when the continent approached the southeast Asia subduction systems on its northward passage from Antartica. Here we explore a suite of eight high-resolution, compressible, global mantle flow retrodictions going back to 50 Ma, using an adoint method with ≈670 million finite elements. These retrodictions show for the first time that these events emerge jointly as part of global Cenozoic mantle flow histories. Our retrodictions involve the dynamic effects from an upper mantle low-viscosity zone, assimilate a past plate-motion model for the tangential surface velocity field, probe the influence of two different present-day mantle state estimates derived from seismic tomography, and acknowledge the rheological uncertainties of dynamic Earth models by taking in four different realizations for the radial mantle viscosity profile, two of which were published previously.We find the retrodicted mantle flow histories are sensitive to the present-day mantle state estimate and the rheological properties of the Earth model, meaning that this input information is testable with inferences gleaned from the geological record. For a deep mantle viscosity of 1.7 × 1022Pa s and a purely thermal interpretation of seismic structure, lowermantle flow velocities exceed 7 cmyr-1in some regions,meaning they are difficult to reconcile with the existence of a hotspot reference frame. Conversely, a deep mantle viscosity of 1023Pa s yields modest flow velocities (< 3 cmyr-1) and stability of deep mantle heterogeneity for much of the retrodiction time, albeit at the expense that African uplift is delayed into the latest Neogene. Retrodictions allow one to track material back in time from any given sampling location, making them potentially useful, for example, to geochemical studies. Our results call for improved estimates on non-isostatic vertical motion of the Earth's surface-provided, for instance, by basin analysis, seismic stratigraphy, landform studies, thermochronological data or the sedimentation record-to constrain the recent mantle flow history and suggest that mantle flow retrodictions may yield synergies across different Earth science disciplines

Humans rather than Eurasian lynx (Lynx lynx) shape ungulate browsing patterns in a temperate forest

The recolonization of human-dominated landscapes by large carnivores has been followed with considerable scientific interest; however, little is known about their interactive effect on ungulate foraging behavior. This study compared the risks imposed by humans and lynx on ungulate foraging behavior by examining the effects of browsing intensity (at two spatial scales), diet quality, and tree species selection. We hypothesized that: (1) in areas with high risk imposed by humans and lynx browsing intensity would be reduced; (2) risk effects would interact with habitat visibility at a fine scale, resulting in contrasting browsing patterns in response to humans versus lynx risk; (3) ungulates compensate for the higher costs incurred in high-risk areas by switching to a higher diet quality, and (4) browse a higher proportion of more-preferred tree species. These hypotheses were tested by measuring browsing intensity along 48 transects located at different distances from human settlements within the hunted and nonhunted areas of the Bavarian Forest. Dung samples were collected and analyzed as a proxy of diet quality (C:N ratio, fiber). The spatial patterns of browsing intensity, diet quality, and tree species selection were then linked to lynx risk, hunting intensity, recreation intensity, and distance to human settlements. Our results showed that (1) browsing intensity strongly decreased with increasing recreational activities, whereas it increased with lynx risk; (2) only in close proximity to human settlements tree browsing was higher in dense habitats and (3) a higher diet quality was obtained. (4) We found a stronger avoidance of the less preferred tree species in high-hunting intensity areas. In conclusion, our results indicate that the risk effects of human activities outweigh those of a natural large carnivore. Thus, highlighting the importance of taking those activities into account in predicting the impacts of large carnivores on ungulates and their plant-food choices.publishedVersio

Factors controlling rare earth element plus yttrium enrichment in Fe–Mn crusts from Canary Islands Seamounts (NE Central Atlantic)

Marine minerals are important because concentrate in their structure high contents of strategic and critical elements as rare earth elements. Forty-two samples from eight seamounts of Canary Islands Seamount Province (CISP) have been analyzed in order to evaluate their rare earth elements plus yttrium contents (REY). Highest contents of REY are related to hydrogenetic minerals and essentially Fe-vernadite (on average 3000 μg/g). Diagenetic minerals, on the other hand, show the lowest REY contents with an average content of 260 μg/g. These differences also depend on the growth rates, hydrogenetic minerals with growth rates between 0.5 and 5 mm/Ma allow the incorporation of more REY in their structure. REY contents in studied samples varies depending several factors associated with depth and location, shallowest samples presumably growth near or within the oxygen minimum zone are the most enriched with up to 3800 μg/g due to local enrichment of these elements and the slowest growth rate promoted by the reduced ambient conditions while deeper samples around 3000 m water depth show 2800 μg/g. Location also has a role in REY contents essentially due to the presence of different currents. Samples faced to north are exposed to the more oxygenated waters of the North Atlantic Deep Water and are depleted in REY if compared with deeper samples facing to south to the more oxic Antarctic Bottom Water. Finally, the case of study made on three different seamounts of the CISP show that Fe–Mn crusts from this area could provide on average 130 tons of hydrometallurgical recovered REY (based on 1 km2 areal crust coverage) together with interesting quantity of several other strategic and base elements as Mn, Co, Ni, Cu, V, Mo between others

The detection of airborne transmission of tuberculosis from HIV-infected patients, using an in vivo air sampling model

Background. Nosocomial transmission of tuberculosis remains an important public health problem. We created an in vivo air sampling model to study airborne transmission of tuberculosis from patients coinfected with human immunodeficiency virus (HIV) and to evaluate environmental control measures. Methods. An animal facility was built above a mechanically ventilated HIV‐tuberculosis ward in Lima, Peru. A mean of 92 guinea pigs were continuously exposed to all ward exhaust air for 16 months. Animals had tuberculin skin tests performed at monthly intervals, and those with positive reactions were removed for autopsy and culture for tuberculosis. Results. Over 505 consecutive days, there were 118 ward admissions by 97 patients with pulmonary tuberculosis, with a median duration of hospitalization of 11 days. All patients were infected with HIV and constituted a heterogeneous group with both new and existing diagnoses of tuberculosis. There was a wide variation in monthly rates of guinea pigs developing positive tuberculin test results (0%–53%). Of 292 animals exposed to ward air, 159 developed positive tuberculin skin test results, of which 129 had laboratory confirmation of tuberculosis. The HIV‐positive patients with pulmonary tuberculosis produced a mean of 8.2 infectious quanta per hour, compared with 1.25 for HIV‐negative patients with tuberculosis in similar studies from the 1950s. The mean monthly patient infectiousness varied greatly, from production of 0–44 infectious quanta per hour, as did the theoretical risk for a health care worker to acquire tuberculosis by breathing ward air. Conclusions. HIV‐positive patients with tuberculosis varied greatly in their infectiousness, and some were highly infectious. Use of environmental control strategies for nosocomial tuberculosis is therefore a priority, especially in areas with a high prevalence of both tuberculosis and HIV infection

Genome analysis of the necrotrophic fungal pathogens Sclerotinia sclerotiorum and Botrytis cinerea

Sclerotinia sclerotiorum and Botrytis cinerea are closely related necrotrophic plant pathogenic fungi notable for their wide host ranges and environmental persistence. These attributes have made these species models for understanding the complexity of necrotrophic, broad host-range pathogenicity. Despite their similarities, the two species differ in mating behaviour and the ability to produce asexual spores. We have sequenced the genomes of one strain of S. sclerotiorum and two strains of B. cinerea. The comparative analysis of these genomes relative to one another and to other sequenced fungal genomes is provided here. Their 38–39 Mb genomes include 11,860–14,270 predicted genes, which share 83% amino acid identity on average between the two species. We have mapped the S. sclerotiorum assembly to 16 chromosomes and found large-scale co-linearity with the B. cinerea genomes. Seven percent of the S. sclerotiorum genome comprises transposable elements compared t

Safety and immunogenicity of AS03B adjuvanted split virion versus non-adjuvanted whole virion H1N1 influenza vaccine in UK children aged 6 months-12 years: open label, randomised, parallel group, multicentre study

Objectives To compare the safety, reactogenicity, and immunogenicity of an adjuvanted split virion H1N1 vaccine and a non-adjuvanted whole virion vaccine used in the pandemic immunisation programme in the United Kingdom

Breeding amphibians in captivity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73877/1/j.1748-1090.1977.tb00864.x.pd

Single-crosslink microscopy in a biopolymer network dissects local elasticity from molecular fluctuations

Polymer networks are fundamental from cellular biology to plastics technology but their intrinsic inhomogeneity is masked by the usual ensemble-averaged measurements. Here, we construct direct maps of crosslinks-symbolic depiction of spatially-distributed elements highlighting their physical features and the relationships between them-in an actin network. We selectively label crosslinks with fluorescent markers, track their thermal fluctuations, and characterize the local elasticity and cross-correlations between crosslinks. Such maps display massive heterogeneity, reveal abundant anticorrelations, and may contribute to address how local responses scale up to produce macroscopic elasticity. Single-crosslink microscopy offers a general, microscopic framework to better understand crosslinked molecular networks in undeformed or strained states