814 research outputs found
Disease Outbreaks and Agricultural Trade: The Case of Potatoes
This study analyzed the impact of PVYn and potato wart disease outbreaks in PEI on the potato industry. These disease outbreaks resulted in the loss of the US seed export market to PEI producers. The effects of the disease outbreaks were mitigated through value-added processing. Price premiums for processed potatoes allowed PEI potato producers to abandon seed exports without incurring losses. Evidence is presented to suggest that other countries have also used this approach when export restrictions were placed on domestic agricultural industries. Policy response to the two disease outbreaks include: i) development of a zones policy that helped to reopen markets into the US; and ii) financial compensation to producers above the minimum levels required under the Seeds Act and Regulations. Implementation of the zones policy had beneficial impacts on the potato industry and is mirrored in other disease outbreaks. In contrast, compensation above minimum requirements may set a costly precedent for future disease outbreaks and may have caused moral hazard problems.disease, trade, potatoes, Canada, food, safety, Agricultural and Food Policy, International Development, International Relations/Trade,
Molecular mechanisms underlying the effects of statins in the central nervous system
3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, commonly referred to as statins, are widely used in the treatment of dyslipidaemia, in addition to providing primary and secondary prevention against cardiovascular disease and stroke. Statins’ effects on the central nervous system (CNS), particularly on cognition and neurological disorders such as stroke and multiple sclerosis, have received increasing attention in recent years, both within the scientific community and in the media. Current understanding of statins’ effects is limited by a lack of mechanism-based studies, as well as the assumption that all statins have the same pharmacological effect in the central nervous system. This review aims to provide an updated discussion on the molecular mechanisms contributing to statins’ possible effects on cognitive function, neurodegenerative disease, and various neurological disorders such as stroke, epilepsy, depression and CNS cancers. Additionally, the pharmacokinetic differences between statins and how these may result in statin-specific neurological effects are also discussed
Pandemic (H1N1) 2009 influenza community transmission was established in one Australian state when the virus was first identified in North America
BACKGROUND In mid-June 2009 the State of Victoria in Australia appeared to have the highest notification rate of pandemic (H1N1) 2009 influenza in the world. We hypothesise that this was because community transmission of pandemic influenza was already well established in Victoria at the time testing for the novel virus commenced. In contrast, this was not true for the pandemic in other parts of Australia, including Western Australia (WA). METHODS We used data from detailed case follow-up of patients with confirmed infection in Victoria and WA to demonstrate the difference in the pandemic curve in two Australian states on opposite sides of the continent. We modelled the pandemic in both states, using a susceptible-infected-removed model with Bayesian inference accounting for imported cases. RESULTS Epidemic transmission occurred earlier in Victoria and later in WA. Only 5% of the first 100 Victorian cases were not locally acquired and three of these were brothers in one family. By contrast, 53% of the first 102 cases in WA were associated with importation from Victoria. Using plausible model input data, estimation of the effective reproductive number for the Victorian epidemic required us to invoke an earlier date for commencement of transmission to explain the observed data. This was not required in modelling the epidemic in WA. CONCLUSION Strong circumstantial evidence, supported by modelling, suggests community transmission of pandemic influenza was well established in Victoria, but not in WA, at the time testing for the novel virus commenced in Australia. The virus is likely to have entered Victoria and already become established around the time it was first identified in the US and Mexico
ACE2 Deficiency Worsens Epicardial Adipose Tissue Inflammation and Cardiac Dysfunction in Response to Diet-Induced Obesity
Obesity is increasing in prevalence and is strongly associated with metabolic and cardiovascular disorders. The renin-angiotensin system (RAS) has emerged as a key pathogenic mechanism for these disorders; angiotensin (Ang)-converting enzyme 2 (ACE2) negatively regulates RAS by metabolizing Ang II into Ang 1-7. We studied the role of ACE2 in obesity-mediated cardiac dysfunction. ACE2 null (ACE2KO) and wild-type (WT) mice were fed a high-fat diet (HFD) or a control diet and studied at 6 months of age. Loss of ACE2 resulted in decreased weight gain but increased glucose intolerance, epicardial adipose tissue (EAT) inflammation, and polarization of macrophages into a proinflammatory phenotype in response to HFD. Similarly, human EAT in patients with obesity and heart failure displayed a proinflammatory macrophage phenotype. Exacerbated EAT inflammation in ACE2KO-HFD mice was associated with decreased myocardial adiponectin, decreased phosphorylation of AMPK, increased cardiac steatosis and lipotoxicity, and myocardial insulin resistance, which worsened heart function. Ang 1-7 (24 µg/kg/h) administered to ACE2KO-HFD mice resulted in ameliorated EAT inflammation and reduced cardiac steatosis and lipotoxicity, resulting in normalization of heart failure. In conclusion, ACE2 plays a novel role in heart disease associated with obesity wherein ACE2 negatively regulates obesity-induced EAT inflammation and cardiac insulin resistance
Highly Polarized Optically-Selected BL Lacertae Objects
Observations of candidate BL Lacertae objects spectroscopically selected from
the Sloan Digital Sky Survey (SDSS) reveal a large fraction with high
polarization (P > 3%). This result confirms that synchrotron radiation makes an
important contribution to the observed optical continuum for most objects in
the sample. The SDSS sample can be divided into separate categories, with
objects of undetermined redshift generally having the highest optical
polarization. Polarization as high as 23% and the lack of spectral features
suggests that the synchrotron continuum completely dominates the spectra of
these sources. The mean polarization levels observed for objects having
measured redshifts is much lower, with the maximum observed polarization for
this group being ~10%. The lower polarizations of these objects are reminiscent
of the less spectacular polarization levels shown by BL Lac objects discovered
in X-ray surveys. We find no SDSS BL Lac candidates at z > 1 with P > 3%,
calling their classification as BL Lac objects into question. In addition, the
existence of radio-quiet BL Lac objects is not verified since none of 10
potentially radio-weak BL Lac candidates observed are highly polarized.
Regardless of whether the high-redshift and radio-weak objects are included in
this optical sample, the overall levels of polarization observed are
intermediate between those seen for X-ray and radio-selected BL Lac objects.Comment: 9 pages, 3 figures, 2 table
Simplified novel muraymycin analogues ; using a serine template strategy for linking key pharmacophores
The present status of antibiotic research requires the urgent invention of novel agents that act on multidrug-resistant bacteria. The World Health Organization has classified antibiotic-resistant bacteria into critical, high and medium priority according to the urgency of need for new antibiotics. Naturally occurring uridine-derived "nucleoside antibiotics" have shown promising activity against numerous priority resistant organisms by inhibiting the transmembrane protein MraY (translocase I), which is yet to be explored in a clinical context. The catalytic activity of MraY is an essential process for bacterial cell viability and growth including that of priority organisms. Muraymycins are one subclass of naturally occurring MraY inhibitors. Despite having potent antibiotic properties, the structural complexity of muraymycins advocates for simplified analogues as potential lead structures. Herein, we report a systematic structure-activity relationship (SAR) study of serine template-linked, simplified muraymycin-type analogues. This preliminary SAR lead study of serine template analogues successfully revealed that the complex structure of naturally occurring muraymycins could be easily simplified to afford bioactive scaffolds against resistant priority organisms. This study will pave the way for the development of novel antibacterial lead compounds based on a simplified serine template. [Abstract copyright: © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Predictors of clinical recovery from concussion: a systematic review
Objective: A systematic review of factors that might be associated with, or influence, clinical recovery from sport-related concussion. Clinical recovery was defined functionally as a return to normal activities, including school and sports, following injury. Design: Systematic review. Data sources PubMed, PsycINFO, MEDLINE, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus and Web of Science. Eligibility criteria for selecting studies Studies published by June of 2016 that addressed clinical recovery from concussion. Results: A total of 7617 articles were identified using the search strategy, and 101 articles were included. There are major methodological differences across the studies. Many different clinical outcomes were measured, such as symptoms, cognition, balance, return to school and return to sports, although symptom outcomes were the most frequently measured. The most consistent predictor of slower recovery from concussion is the severity of a person’s acute and subacute symptoms. The development of subacute problems with headaches or depression is likely a risk factor for persistent symptoms lasting greater than a month. Those with a preinjury history of mental health problems appear to be at greater risk for having persistent symptoms. Those with attention deficit hyperactivity disorder (ADHD) or learning disabilities do not appear to be at substantially greater risk. There is some evidence that the teenage years, particularly high school, might be the most vulnerable time period for having persistent symptoms—with greater risk for girls than boys. Conclusion: The literature on clinical recovery from sport-related concussion has grown dramatically, is mostly mixed, but some factors have emerged as being related to outcome
Reconstituted B cell receptor signaling reveals carbohydrate-dependent mode of activation
Activation of immune cells (but not B cells) with lectins is widely known. We used the structurally defined interaction between influenza hemagglutinin (HA) and its cell surface receptor sialic acid (SA) to identify a B cell receptor (BCR) activation modality that proceeded through non-cognate interactions with antigen. Using a new approach to reconstitute antigen-receptor interactions in a human reporter B cell line, we found that sequence-defined BCRs from the human germline repertoire could be triggered by both complementarity to influenza HA and a separate mode of signaling that relied on multivalent ligation of BCR sialyl-oligosaccharide. The latter suggested a new mechanism for priming naïve B cell responses and manifested as the induction of SA-dependent pan-activation by peripheral blood B cells. BCR crosslinking in the absence of complementarity is a superantigen effect induced by some microbial products to subvert production of antigen-specific immune responses. B cell superantigen activity through affinity for BCR carbohydrate is discussed
Physics-Based Modeling of Meteor Entry and Breakup
A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup.Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood.On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/sq cm. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to spherical geometries of diameters ranging from 1 to 100 m for an entry velocity of 20 kms and stagnation pressures ranging from 1 to 100 atm; (ii) the influence of shape and departure of heating environment predictions from those for a simple spherical geometry; (iii) assessment of thermal response models for silica subject to intense radiation; and (iv) results for porosity-driven gross fragmentation of meteors, idealized as a collection of smaller objects. Lessons learned from these simulations will be used to help understand the Chelyabinsk meteor entry up to its first point of fragmentation
Photospheric observations of surface and body modes in solar magnetic pores
Over the past number of years, great strides have been made in identifying the various low-order magnetohydrodynamic wave modes observable in a number of magnetic structures found within the solar atmosphere. However, one aspect of these modes that has remained elusive, until now, is their designation as either surface or body modes. This property has significant implications for how these modes transfer energy from the waveguide to the surrounding plasma. Here, for the first time to our knowledge, we present conclusive, direct evidence of these wave characteristics in numerous pores that were observed to support sausage modes. As well as outlining methods to detect these modes in observations, we make estimates of the energies associated with each mode. We find surface modes more frequently in the data, as well as that surface modes appear to carry more energy than those displaying signatures of body modes. We find frequencies in the range of ~2–12 mHz, with body modes as high as 11 mHz, but we do not find surface modes above 10 mHz. It is expected that the techniques we have applied will help researchers search for surface and body signatures in other modes and in differing structures from those presented here
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