147 research outputs found

    The Secret Life of the Anthrax Agent Bacillus anthracis: Bacteriophage-Mediated Ecological Adaptations

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    Ecological and genetic factors that govern the occurrence and persistence of anthrax reservoirs in the environment are obscure. A central tenet, based on limited and often conflicting studies, has long held that growing or vegetative forms of Bacillus anthracis survive poorly outside the mammalian host and must sporulate to survive in the environment. Here, we present evidence of a more dynamic lifecycle, whereby interactions with bacterial viruses, or bacteriophages, elicit phenotypic alterations in B. anthracis and the emergence of infected derivatives, or lysogens, with dramatically altered survival capabilities. Using both laboratory and environmental B. anthracis strains, we show that lysogeny can block or promote sporulation depending on the phage, induce exopolysaccharide expression and biofilm formation, and enable the long-term colonization of both an artificial soil environment and the intestinal tract of the invertebrate redworm, Eisenia fetida. All of the B. anthracis lysogens existed in a pseudolysogenic-like state in both the soil and worm gut, shedding phages that could in turn infect non-lysogenic B. anthracis recipients and confer survival phenotypes in those environments. Finally, the mechanism behind several phenotypic changes was found to require phage-encoded bacterial sigma factors and the expression of at least one host-encoded protein predicted to be involved in the colonization of invertebrate intestines. The results here demonstrate that during its environmental phase, bacteriophages provide B. anthracis with alternatives to sporulation that involve the activation of soil-survival and endosymbiotic capabilities

    SN 2022oqm-A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material

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    We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after the explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high ionization C and O absorption features at velocities of 4000 km s−1, while its photospheric radius expands at 20,000 km s−1, indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s−1, in agreement with the evolution of the photospheric radius. The optical light curves reach a second peak at t ≈ 15 days. By t = 60 days, the spectrum of SN 2022oqm becomes nearly nebular, displaying strong Ca ii and [Ca ii] emission with no detectable [O i], marking this event as Ca-rich. The early behavior can be explained by 10−3 M ⊙ of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf-Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both the interaction of the ejecta with the optically thin CSM and shock cooling (in the massive star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent

    Comparing Risk Factor Profiles between Intracerebral Hemorrhage and Ischemic Stroke in Chinese and White Populations:Systematic Review and Meta-Analysis

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    <div><p>Background</p><p>Chinese populations have a higher proportion of intracerebral hemorrhage (ICH) in total strokes. However, the reasons are not fully understood.</p><p>Methods</p><p>To assess the differences in frequency of major risk factors between ICH and ischemic stroke (IS) in Chinese versus white populations of European descent, we systematically sought studies conducted since 1990 that compared frequency of risk factors between ICH and IS in Chinese or white populations. For each risk factor, in Chinese and Whites separately, we calculated study-specific and random effects pooled prevalence and odds ratios (ORs) for ICH versus IS.</p><p>Results</p><p>Six studies among 36190 Chinese, and seven among 52100 white stroke patients studied hypertension, diabetes, atrial fibrillation (AF), ischemic heart disease (IHD), hypercholesterolemia, smoking and alcohol. Pooled prevalence of AF was significantly lower in Chinese. Pooled ORs for ICH versus IS were mostly similar in Chinese and Whites. However, in Chinese–but not Whites–mean age was lower (62 versus 69 years), while hypertension and alcohol were significantly more frequent in ICH than IS (ORs 1.38, 95% CI 1.18–1.62, and 1.46, 1.12–1.91). Hypercholesterolemia and smoking were significantly less frequent in ICH in Whites, but not Chinese, while IHD, AF and diabetes were less frequent in ICH in both.</p><p>Conclusions</p><p>Different risk factor distributions in ICH and IS raise interesting possibilities about variation in mechanisms underlying the different distributions of pathological types of stroke between Chinese and Whites. Further analyses in large, prospective studies, including adjustment for potential confounders, are needed to consolidate and extend these findings.</p></div

    Diabetic ketoacidosis

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    Diabetic ketoacidosis (DKA) is the most common acute hyperglycaemic emergency in people with diabetes mellitus. A diagnosis of DKA is confirmed when all of the three criteria are present — ‘D’, either elevated blood glucose levels or a family history of diabetes mellitus; ‘K’, the presence of high urinary or blood ketoacids; and ‘A’, a high anion gap metabolic acidosis. Early diagnosis and management are paramount to improve patient outcomes. The mainstays of treatment include restoration of circulating volume, insulin therapy, electrolyte replacement and treatment of any underlying precipitating event. Without optimal treatment, DKA remains a condition with appreciable, although largely preventable, morbidity and mortality. In this Primer, we discuss the epidemiology, pathogenesis, risk factors and diagnosis of DKA and provide practical recommendations for the management of DKA in adults and children

    Suppression in Pb-Pb Collisions at the LHC.

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    The production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5<y<4). The measurement of the ratio of the inclusive production cross sections of the ψ(2S) and J/ψ resonances is reported as a function of the centrality of the collisions and of transverse momentum, in the region p_{T}<12  GeV/c. The results are compared with the corresponding measurements in pp collisions, by forming the double ratio [σ^{ψ(2S)}/σ^{J/ψ}]_{Pb-Pb}/[σ^{ψ(2S)}/σ^{J/ψ}]_{pp}. It is found that in Pb-Pb collisions the ψ(2S) is suppressed by a factor of ∼2 with respect to the J/ψ. The ψ(2S) nuclear modification factor R_{AA} was also obtained as a function of both centrality and p_{T}. The results show that the ψ(2S) resonance yield is strongly suppressed in Pb-Pb collisions, by a factor of up to ∼3 with respect to pp. Comparisons of cross section ratios with previous Super Proton Synchrotron findings by the NA50 experiment and of R_{AA} with higher-p_{T} results at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC

    Effect of subsurface drainage on rabi crops in the flood prone areas of Dankuni basin in West Bengal

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    Field trials were conducted during rabi seasons of 1997-98 and 1998-99 in the flood prone areas of Dankuni basin to investigate the techno-economic feasibility of subsurface tile drainage on four important crops. The study revealed that with the adoption of drainage measures the economic yield of crop was increased by 79.2 per cent for mustard, 111.9 per cent for pea, 74.7 per cent for okra and 115.7 per cent for wheat, respectively as compared with control. The average gross and net returns and benefit-cost ratio is also higher in case of adoption of drainage measures indicating its feasibility in this situation. There was a considerable loss of plant nutrients in the form of organic matter, available P and K through drainage water and therefore, needs its application regularly

    Uncovering allostery and regulation in SAMHD1 through molecular dynamics simulations

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    The human sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a retroviral restriction factor in myeloid cells and non-cycling CD4+ T cells, a feature imputed to its phosphohydrolase activitythe enzyme depletes the cellular dNTP levels inhibiting reverse transcription. The functionally active form of SAMHD1 is an allosterically triggered tetramer which utilizes GTP-Mg+2-dNTP cross bridges to link and stabilize adjacent monomers. However, very little is known about how it assembles into a tetramer and how long the tetramer stays intact. In this computational study, we provide a molecular dynamics based analysis of the structural stability and allosteric site dynamics in SAMHD1. We have investigated the allosteric links which assemble and hold the tetramer together. We have also extended this analysis to a regulatory mutant of SAMHD1. Experimental studies have indicated that phosphorylation of T592 downregulates HIV-1 restriction. A similar result is also achieved by a phosphomimetic mutation T592E. While a mechanistic understanding of the process is still elusive, the loss of structural integrity of the enzyme is conjectured to be the cause of the impaired dNTPase activity of the T592E mutant. MD simulations show that the T592E mutation causes slightly elevated local motions which remain confined to the short helix (residues 591-595), which contains the phosphorylation site and do not cause long-range destabilization of the SAMHD1 tetramer within the timeframe of the simulations. Thus, the regulatory mechanism of SAMHD1 is a more subtle mechanism than has been previously suspected. Proteins 2017; 85:1266-1275. (c) 2017 Wiley Periodicals, Inc

    Ethnoveterinary practices for small ruminants followed by rural folks in southern Odisha

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    319-324The present study is aimed at identification of the traditional medical practices being adopted by the rural folks in the treatment of small ruminant diseases in Bhawanipatna block in Kalahandi district of Odisha state. Extensive field survey in 12 villages (Manoharpur, Medinpur, Sujanpur, Jammunabahal, Balarampur, Sagadia, Ichchapur, Sanakhairamala, Kadappa, Chhatiguda, Bangabadi, Kadapada) in and around Bhawanipatna was carried out through 36 regular and repeated informal visits, and 160 informants residing in these villages were consulted through participatory rural appraisal method. Information was gathered through open interaction and door to door interview, and through personal interrogation. A total of 23 species of herbal plants have been identified which were used either alone or in combination as traditional remedies for 24 different conditions/ diseases in livestock including important conditions like hoof infection, liver disorder and enteritis to emergency conditions like tympany/ bloat and hemorrhage. About 2000 small ruminants have been treated by the total informants over the years with the use of herbal remedies. The success rate of the practices used was claimed by the native folk to be 50-60 %. Use of such medicinal plants is of greater value in view of the socioeconomic conditions of the small ruminants owners in reducing the cost of treatment. </span
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