The prevalence and proliferation of antibiotic resistant bacteria is profoundly important to human health, but the extent to which aquatic environments contribute toward the dissemination of ...antibiotic resistant genes (ARGs) is poorly understood. The prevalence of 24 ARGs active against eight antibiotic classes (β-lactams, aminoglycosides, glycopeptides, chloramphenicols, tetracycline, macrolides, trimethoprim, and sulfonamides) was evaluated in surface water samples collected from Germany and Australia with culture independent methods. The ARGs most frequently detected both in Germany and Australia were sulI, sulII (77–100%), and dfrA1 (43–55%) which code for resistance to sulfonamide and trimethoprim. Macrolides resistance gene ermB was relatively more prevalent in the surface water from Germany (68%) than Australia (18%). In contrast, the chloramphenicol resistance gene catII was more frequently detected in Australia (64%) than Germany (9%). Similarly, β-lactams resistance gene ampC was more prevalent in the samples from Australia (36%) than Germany (19%). This study highlights wide distribution of ARGs for sulfonamide, trimethoprim, macroline, β-lactams and chloramphenicol in the aquatic ecosystems. Aquatic ecosystems can therefore be reservoirs of ARGs genes which could potentially be transferred from commensal microorganisms to human pathogens.
Maturation rates of malaria parasites within red blood cells (RBCs) can be influenced by host nutrient status and circadian rhythm; whether host inflammatory responses can also influence maturation ...remains less clear. Here, we observed that systemic host inflammation induced in mice by an innate immune stimulus, lipopolysaccharide (LPS), or by ongoing acute
infection, slowed the progression of a single cohort of parasites from one generation of RBC to the next. Importantly, plasma from LPS-conditioned or acutely infected mice directly inhibited parasite maturation during in vitro culture, which was not rescued by supplementation, suggesting the emergence of inhibitory factors in plasma. Metabolomic assessments confirmed substantial alterations to the plasma of LPS-conditioned and acutely infected mice, and identified a small number of candidate inhibitory metabolites. Finally, we confirmed rapid parasite responses to systemic host inflammation
using parasite scRNA-seq, noting broad impairment in transcriptional activity and translational capacity specifically in trophozoites but not rings or schizonts. Thus, we provide evidence that systemic host inflammation rapidly triggered transcriptional alterations in circulating blood-stage Plasmodium trophozoites and predict candidate inhibitory metabolites in the plasma that may impair parasite maturation
. IMPORTANCE Malaria parasites cyclically invade, multiply, and burst out of red blood cells. We found that a strong inflammatory response can cause changes to the composition of host plasma, which directly slows down parasite maturation. Thus, our work highlights a new mechanism that limits malaria parasite growth in the bloodstream.
Anesthesia is currently required for positron emission tomography (PET) studies of the animal brain in order to eliminate motion artifacts. However, anesthesia profoundly affects the neurological ...state of the animal, complicating the interpretation of PET data. Furthermore, it precludes the use of PET to study the brain during normal behavior. The rat conscious animal PET tomograph (RatCAP) is designed to eliminate the need for anesthesia in rat brain studies. It is a miniaturized full-ring PET scanner that is attached directly to the head, imaging nearly the entire brain. RatCAP utilizes arrays of 2 mm /spl times/ 2 mm LSO crystals coupled to matching avalanche photodiode arrays, which are in turn read out by full custom integrated circuits. Principal challenges have been addressed considering the physical constraints on size, weight, and heat generation in addition to the usual requirements of small-animal PET, such as high spatial resolution in the presence of parallax error. A partial prototype has been constructed and preliminary measurements and optimization completed. Realistic Monte Carlo simulations have also been carried out to optimize system performance, which is predicted to be competitive with existing microPET systems.
Sport tourism entity desired outcomes Stoll, Jennifer A.; Dixon, Anthony W.; Goldsmith, Andrew L. ...
The journal of sport tourism,
07/2020, Letnik:
24, Številka:
3
Journal Article
Recenzirano
Sport tourism entities serve to actively represent a locale in hosting sporting events across the United States and beyond (Sports ETA, 2019). Over the last quarter century, the number of sport ...tourism entities has ballooned from 13 to more than 500 expanding from the U.S. to Canada and Puerto Rico Sports Events & Tourism Association. (2018a). About the National Association of Sports Commissions.
https://www.sportscommissions.org/about
. However, scant research exists regarding the efforts of these entities in the larger context of sport management and tourism scholarship. The purpose of this study was to gain an understanding as to what sport tourism entities seek to achieve as a foundational effort to later explore if these outcomes are pursued or measured. The researchers conducted a content analysis of sport tourism entity mission statements (n = 132) to determine organizational desired outputs and outcomes. The analysis yielded one sport tourism entity primary output and five primary desired outcomes. Additional outcomes and qualifiers were also identified.
Angiotensin II (ANG II) is known to be a potent growth promoting factor for vascular smooth muscle cells and fibroblasts but little is known about its influence on growth in endothelial cells. We ...studied the effects of ANG II on endothelial growth and the role of the angiotensin receptor subtypes involved. Proliferation of rat coronary endothelial cells (CEC) and rat vascular smooth muscle cells (VSMC) was determined by 3Hthymidine incorporation, the MTT-test and by directly counting cells in a coulter counter. Angiotensin AT1- and AT2-receptors were demonstrated by binding studies and by the presence of their respective mRNA through reverse transcription polymerase chain reaction (RT-PCR). In contrast to VSMC, which in culture only express the AT1-receptor, CEC express both, AT1- and AT2-receptors simultaneously up to the third passage. Whereas ANG II stimulated growth of quiescent VSMC, an effect abolished by pretreatment with the AT1-receptor antagonist, losartan, ANG II did not induce proliferation in quiescent CEC. However, after pretreatment of quiescent endothelial cells (< passage 4) with the AT2-receptor antagonist, PD 123177, ANG II induced proliferation. This effect was reversed by additional pretreatment with losartan. ANG II significantly inhibited the proliferation of bFGF-stimulated CEC in a dose-dependent manner by maximally 50%. This effect was prevented by PD 123177 while losartan was ineffective. The AT2-receptor agonist, CGP 42112, mimicked the antiproliferative actions of ANG II, confirming the specificity of the effect. Our results show that the growth modulating actions of ANG II depend on the type of angiotensin receptor present on a given cell. In coronary endothelial cells, the antiproliferative actions of the AT2-receptor offset the growth promoting effects mediated by the AT1-receptor.
— Noble gas data from Martian meteorites have provided key constraints about their origin and evolution, and their parent body. These meteorites have witnessed varying shock metamorphic overprinting ...(at least 5 to 14 GPa for the nakhlites and up to 45–55 GPa (e.g., the lherzolitic shergottite Allan Hills ALH A77005), solar heating, cosmic‐ray exposure, and weathering both on Mars and Earth. Influences on the helium budgets of Martian meteorites were evaluated by using a new data set and literature data. Concentrations of 3He, 4He, U, and Th are measured and shock pressures for same sample aliquots of 13 Martian meteorites were determined to asses a possible relationship between shock pressure and helium concentration. Partitioning of 4He into cosmogenic and radiogenic components was performed using the lowest 4He/3He ratio we measured on mineral separates (4He/3He = 4.1, pyroxene of ALHA77005). Our study revealed significant losses of radiogenic 4He. Systematics of cosmogenic 3He and neon led to the conclusion that solar radiation heating during transfer from Mars to Earth and terrestrial weathering can be ruled out as major causes of the observed losses of radiogenic helium in bulk meteorites. For bulk rock we observed a correlation of shock pressure and radiogenic 4He loss, ranging between ˜20% for Chassigny and other moderately shocked Martian meteorites up to total loss for meteorites shocked above 40 GPa. A steep increase of loss occurs around 30 GPa, the pressure at which plagioclase transforms to maskelynite. This correlation suggests significant 4He loss induced by shock metamorphism. Noble gas loss in rocks is seen as diffusion due to (1) the temperature increase during shock loading (shock temperature) and (2) the remaining waste heat after adiabatic unloading (post shock temperature). Modeling of 4He diffusion in the main U, Th carrier phase apatite showed that post‐shock temperatures of ˜300 °C are necessary to explain observed losses. This temperature corresponds to the post‐shock temperature calculated for bulk rocks shocked at about 40 GPa. From our investigation, data survey, and modeling, we conclude that the shock event during launch of the meteorites is the principal cause for 4He loss.
The RatCAP has been designed and constructed to image the awake rat brain. In order to maximize system performance, offline digital coincidence data processing algorithms including offset delay ...correction and prompt and delayed coincidence detection have been developed and validated. With offset delay correction using a singular value decomposition (SVD) technique, overall time resolution was improved from 32.6 to 17.6 ns FWHM. The experimental results confirm that the ratio of prompts to randoms was improved because a narrower timing window could be used. 18 F-fluoride rat bone scan data were reconstructed using our fully 3-D ML-EM algorithm with a highly accurate detector response model created from Monte Carlo simulation.
A study on the properties of lead tungstate crystals Zhu, R.Y.; Ma, D.A.; Newman, H.B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/1996, Letnik:
376, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This report summarizes the results of a study on the properties of five large and five small size lead tungstate (PbWO
4) crystals. Data are presented on the longitudinal optical transmittance and ...light attenuation length, light yield and response uniformity, emission spectra and decay time. The radiation resistance of large crystals and possible curing with optical bleaching are discussed. The result of an in depth materials study, including trace impurities analysis, are also presented. The general conclusion from this investigation is that further research and development is needed to develop fast, radiation-hard PbWO
4 crystals for the CMS experiment at the CERN LHC.
The chemical mechanism of a retaining β-mannosidase from Cellulomonas fimi has been characterized through steady-state kinetic analyses with a range of substrates, coupled with chemical rescue ...studies on both the wild-type enzyme and mutants in which active site carboxyl groups have been replaced. Studies with a series of aryl β-mannosides of vastly different reactivities (pK a lg = 4−10) allowed kinetic isolation of the glycosylation and deglycosylation steps. Substrate inhibition was observed for all but the least reactive of these substrates. Brønsted analysis of k cat revealed a downward breaking plot (βlg = −0.54 ± 0.05) that is consistent with a change in rate-determining step (glycosylation to deglycosylation), and this was confirmed by partitioning studies with ethylene glycol. The pH dependence of k cat/K m follows an apparent single ionization of a group of pK a = 7.65 that must be protonated for catalysis. The tentative assignment of E429 as the acid−base catalyst of Man2A on the basis of sequence alignments with other family 2 glycosidases was confirmed by the increased turnover rate observed for the mutant E429A in the presence of azide and fluoride, leading to the production of β-mannosyl azide and β-mannosyl fluoride, respectively. A pH-dependent chemical rescue of E429A activity is also observed with citrate. Substantial oxocarbenium ion character at the transition state was demonstrated by the α-deuterium kinetic isotope effect for Man2A E429A of α-D( V ) = 1.12 ± 0.01. Surprisingly, this isotope effect was substantially greater in the presence of azide (α-D( V ) = 1.166 ± 0.009). Likely involvement of acid/base catalysis was revealed by the pH dependence of k cat for Man2A E429A, which follows a bell-shaped profile described by pK a values of 6.1 and 8.4, substantially different from that of the wild-type enzyme. The glycosidic bond cleaving activity of Man2A E519A and E519S nucleophile mutants is restored with azide and fluoride and appears to correlate with the corresponding “glycosynthase” activities. The contribution of the substrate 2-hydroxyl to stabilization of the Man2A glycosylation transition state (ΔΔG ⧧ = 5.1 kcal mol-1) was probed using a 2-deoxymannose substrate. This value, surprisingly, is comparable to that found from equivalent studies with β-glucosidases despite the geometric differences at C-2 and the importance of hydrogen bonding at that position. Modes of stabilizing the mannosidase transition state are discussed.
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