Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 64
Filtrar
1.
PLoS One ; 19(7): e0300870, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39024232

RESUMO

Rapid growth in outdoor recreation may have important and varied effects on terrestrial mammal communities. Few studies have investigated factors influencing variation in observed responses of multiple mammal species to recreation. We used data from 155 camera traps, in western Alberta (Canada), and a hierarchical Bayesian community modelling framework to document 15 mammal species responses to recreation, test for differential responses between predators and prey, and evaluate the influence of local context. Factors characterizing context were trail designation (i.e., use by motorized vs non-motorized), management type, forest cover, landscape disturbance, and season. We used three measures to characterize variation in recreation pressure: distance to trail, trail density, and an index of recreation intensity derived from the platform Strava. We found limited evidence for strong or consistent effects of recreation on mammal space use. However, mammal space use was better explained by an interaction between recreation and the influencing factors than by either on their own. The strongest interaction was between trail density and management type; mammals were more likely to avoid sites near a higher density of trails in areas with more restrictive management. We found that responses to recreation varied with the trail designation, although there were not clear or consistent differences between responses to trails designated for motorized vs. non-motorized use. Overall, we found that responses were species- and context-dependent. Limiting the density of trails may be important for reducing negative impacts to mammals within conservation areas. We show that using multiple measures of recreation yields more insight into the varied effects of human disturbances on wildlife. We recommend investigating how different characteristics of recreation (noise, speed, and visibility) influence animal behaviors. Multispecies monitoring and modelling across multiple landscapes that vary in recreation pressure can lead to an adaptive management approach to ensuring outdoor recreation coexistence with wildlife.


Assuntos
Mamíferos , Recreação , Animais , Mamíferos/fisiologia , Humanos , Alberta , Ecossistema , Conservação dos Recursos Naturais , Teorema de Bayes
2.
J Environ Qual ; 2024 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-39036853

RESUMO

Semiarid rangelands throughout the western Great Plains support livestock production and many other ecosystem services. The degree to which adaptive multi-paddock (AMP) grazing management approaches can help achieve desired ecosystem services remains unclear. At the Central Plains Experimental Range in northeastern Colorado, a management-science partnership with a diverse stakeholder group is comparing collaborative adaptive rangeland management (CARM), designed to incorporate AMP principles, to traditional rangeland management (TRM), consisting of season-long grazing during the growing season. Each treatment was implemented on a set of 10, 130-ha pastures paired by soils, topography, and plant communities to evaluate how CARM affects vegetation (composition and production), livestock production (steer weight gain), and wildlife habitat (vegetation structure for grassland birds). For the first 5 years of the experiment, CARM cattle were managed as a single herd using AMP grazing with planned year-long rest in 20% of the pastures. Relative to TRM, CARM enhanced heterogeneity in vegetation structure across the landscape, benefiting two grassland bird species. However, this came at the cost of 12%-16% lower steer weight gains in CARM versus TRM and declining populations of a third bird species of conservation concern in both treatments. Here we discuss how increased understanding of ecological and social processes during the experiment's first 5 years led to changes in the CARM treatment and management objectives during the next 5 years. We also discuss how innovations in remote sensing, environmental sensors, ecosystem modeling, social learning, and economic analyses are being integrated into and supported by the CARM experiment.

3.
Opt Lett ; 49(6): 1473-1476, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38489428

RESUMO

The electronic excitation of key combustion species or flow tagging of chemical species requires a narrowband tunable UV source. In this work, a potassium titanyl phosphate (KTP) burst-mode optical parametric oscillator (OPO) pumped by a 532 nm laser is developed to generate a spectrally narrow signal and an idler output with 1.48 ± 0.19 cm-1 bandwidth without the need for injection seeding. The idler (1410-1550 nm range) is further mixed with 355 or 266 nm to generate 284 or 226 nm for OH or NO planar laser-induced fluorescence (PLIF), respectively, with up to 1.9% conversion efficiency from 1064 nm to the UV. MHz-rate burst profiles are reported, and OH and NO PLIF are demonstrated in a rotating detonation combustor at rates up to 200 kHz.

4.
Sci Rep ; 13(1): 19944, 2023 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-37968300

RESUMO

Chitin is an abundant, carbon-rich polymer in the marine environment. Chitinase activity has been detected in spent media of Synechococcus WH7803 cultures-yet it was unclear which specific enzymes were involved. Here we delivered a CRISPR tool into the cells via electroporation to generate loss-of-function mutants of putative candidates and identified ChiA as the enzyme required for the activity detected in the wild type.


Assuntos
Quitinases , Synechococcus , Synechococcus/genética , Synechococcus/metabolismo , Quitina/metabolismo , Quitinases/genética , Quitinases/metabolismo
5.
Appl Opt ; 62(29): 7560-7570, 2023 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-37855462

RESUMO

The development of atmospheric hypersonic flight and re-entry capabilities requires the characterization of the thermo-chemical state of representative test environments. This study demonstrates the usage of multiplex nanosecond N 2 coherent anti-Stokes Raman scattering (CARS) to measure temperatures in an atmospheric, high-temperature (>6000K), air plasma plume, generated by an inductively coupled plasma torch. These are some of the highest temperatures ever accessed via gas-phase CARS, to our knowledge. Temperatures of N 2 in the equilibrium plasma plume are determined via theoretical fits to measured CARS spectra. We discuss the practical implementation of CARS at very high temperatures, including the scaling of the N 2 CARS signal strength from 300 to 6700 K, where the expected peak signal from the high-temperature plasma torch gases is two orders of magnitude less than commonly encountered in combustion environments. An intensified CCD camera enables single-laser-shot detection at temperatures as high as 6200 K, by increasing sensitivity and providing a time gate against intense background luminosity. We also discuss the impacts of unwanted two-beam CARS contributions from outside the nominal three-beam measurement volume. We present mean axial and radial temperature profiles, as well as time-series data derived from both single-laser-shot and accumulated CARS spectra. The single-laser-shot precision is 1.7%-2.6% at temperatures of 3500 to 6200 K. The presented results pave the way for the use of CARS at very high temperatures and the measurement of spatially resolved interface processes in high-enthalpy flows.

7.
Appl Opt ; 62(1): 50-62, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36606849

RESUMO

We demonstrate a hybrid time-frequency spectroscopic method for simultaneous temperature/pressure measurements in nonreacting compressible flows with known gas composition. Hybrid femtosecond-picosecond, pure-rotational coherent anti-Stokes Raman scattering (CARS), with two independent, time-delayed probe pulses, is deployed for single-laser-shot measurements of temperature and pressure profiles along an ∼5-mm line. The theory of dual-probe CARS is presented, along with a discussion of the iterative fitting of experimental spectra. Temperature is obtained from spectra acquired with an early, near-collision-free probe time delay (τ 1=0p s) and pressure from spectra obtained at probe delays of τ 2=150-1000p s, where collisions significantly impact the spectral profile. Unique solutions for temperature and pressure are obtained by iteratively fitting the two spectra to account for small collisional effects observed for the near zero probe delay spectrum. A dual-probe pure-rotational CARS system, in a 1D line-imaging configuration, is developed to demonstrate effectively the simultaneous temperature and pressure profiles recorded along the axial centerline of a highly underexpanded jet. The underexpanded air jet permits evaluation of this hybrid time-frequency domain approach for temperature and pressure measurements across a wide range of low-temperature-low-pressure conditions of interest in supersonic ground-test facilities. Single-laser-shot measurement precisions in both quantities and pressure measurement accuracy are systematically evaluated in the quiet zone upstream of the Mach disk. Precise thermometry approaching 1%-2% is observed in regions of high CARS signal-to-noise ratios. Pressure measurements are optimized at probe time delays where the ratio of the late probe delay to the Raman lifetime exceeds four (τ 2/τ R>4). The impact of low-temperature Raman linewidths on CARS pressure measurements is evaluated, and comparisons of CARS pressures obtained with our recent low-temperature pure-rotational Raman linewidth data and extrapolated high-temperature Q-branch linewidths are presented. Considering all measurements with τ 2/τ R≥4.0, measured pressures were on average 7.9% of the computed isentropic values with average shot-to-shot deviations representing a combination of instrument noise and fluid fluctuations of  5.0%.

8.
Sci Total Environ ; 864: 160992, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36535470

RESUMO

Understanding the relationship between water and production within and across agroecosystems is essential for addressing several agricultural challenges of the 21st century: providing food, fuel, and fiber to a growing human population, reducing the environmental impacts of agricultural production, and adapting food systems to climate change. Of all human activities, agriculture has the highest demand for water globally. Therefore, increasing water use efficiency (WUE), or producing 'more crop per drop', has been a long-term goal of agricultural management, engineering, and crop breeding. WUE is a widely used term applied across a diverse array of spatial scales, spanning from the leaf to the globe, and over temporal scales ranging from seconds to months to years. The measurement, interpretation, and complexity of WUE varies enormously across these spatial and temporal scales, challenging comparisons within and across diverse agroecosystems. The goals of this review are to evaluate common indicators of WUE in agricultural production and assess tradeoffs when applying these indicators within and across agroecosystems amidst a changing climate. We examine three questions: (1) what are the uses and limitations of common WUE indicators, (2) how can WUE indicators be applied within and across agroecosystems, and (3) how can WUE indicators help adapt agriculture to climate change? Addressing these agricultural challenges will require land managers, producers, policy makers, researchers, and consumers to evaluate costs and benefits of practices and innovations of water use in agricultural production. Clearly defining and interpreting WUE in the most scale-appropriate way is crucial for advancing agroecosystem sustainability.

9.
J Am Heart Assoc ; 11(23): e026304, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36444837

RESUMO

Background ATP-sensitive potassium channels are inhibited by ATP and open during metabolic stress, providing endogenous myocardial protection. Pharmacologic opening of ATP potassium channels with diazoxide preserves myocardial function following prolonged global ischemia, making it an ideal candidate for use during cardiac surgery. We hypothesized that diazoxide would reduce myocardial stunning after regional ischemia with subsequent prolonged global ischemia, similar to the clinical situation of myocardial ischemia at the time of revascularization. Methods and Results Swine underwent left anterior descending occlusion (30 minutes), followed by 120 minutes global ischemia protected with hyperkalemic cardioplegia±diazoxide (N=6 each), every 20 minutes cardioplegia, then 60 minutes reperfusion. Cardiac output, time to wean from cardiopulmonary bypass, left ventricular (LV) function, caspase-3, and infarct size were compared. Six animals in the diazoxide group separated from bypass by 30 minutes, whereas only 4 animals in the cardioplegia group separated. Diazoxide was associated with shorter but not significant time to wean from bypass (17.5 versus 27.0 minutes; P=0.13), higher, but not significant, cardiac output during reperfusion (2.9 versus 1.5 L/min at 30 minutes; P=0.05), and significantly higher left ventricular ejection fraction at 30 minutes (42.5 versus 15.8%; P<0.01). Linear mixed regression modeling demonstrated greater left ventricular developed pressure (P<0.01) and maximum change in ventricular pressure during isovolumetric contraction (P<0.01) in the diazoxide group at 30 minutes of reperfusion. Conclusions Diazoxide reduces myocardial stunning and facilitates separation from cardiopulmonary bypass in a model that mimics the clinical setting of ongoing myocardial ischemia before revascularization. Diazoxide has the potential to reduce myocardial stunning in the clinical setting.


Assuntos
Isquemia Miocárdica , Miocárdio Atordoado , Suínos , Animais , Diazóxido/farmacologia , Miocárdio Atordoado/etiologia , Miocárdio Atordoado/prevenção & controle , Canais KATP , Volume Sistólico , Função Ventricular Esquerda , Isquemia , Isquemia Miocárdica/complicações , Isquemia Miocárdica/tratamento farmacológico , Trifosfato de Adenosina
10.
Nature ; 609(7927): 582-589, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36071157

RESUMO

Increased levels of proteases, such as trypsin, in the distal intestine have been implicated in intestinal pathological conditions1-3. However, the players and mechanisms that underlie protease regulation in the intestinal lumen have remained unclear. Here we show that Paraprevotella strains isolated from the faecal microbiome of healthy human donors are potent trypsin-degrading commensals. Mechanistically, Paraprevotella recruit trypsin to the bacterial surface through type IX secretion system-dependent polysaccharide-anchoring proteins to promote trypsin autolysis. Paraprevotella colonization protects IgA from trypsin degradation and enhances the effectiveness of oral vaccines against Citrobacter rodentium. Moreover, Paraprevotella colonization inhibits lethal infection with murine hepatitis virus-2, a mouse coronavirus that is dependent on trypsin and trypsin-like proteases for entry into host cells4,5. Consistently, carriage of putative genes involved in trypsin degradation in the gut microbiome was associated with reduced severity of diarrhoea in patients with SARS-CoV-2 infection. Thus, trypsin-degrading commensal colonization may contribute to the maintenance of intestinal homeostasis and protection from pathogen infection.


Assuntos
Microbioma Gastrointestinal , Intestino Grosso , Simbiose , Tripsina , Administração Oral , Animais , Sistemas de Secreção Bacterianos , Vacinas Bacterianas/administração & dosagem , Vacinas Bacterianas/imunologia , Bacteroidetes/isolamento & purificação , Bacteroidetes/metabolismo , COVID-19/complicações , Citrobacter rodentium/imunologia , Diarreia/complicações , Fezes/microbiologia , Microbioma Gastrointestinal/genética , Humanos , Imunoglobulina A/metabolismo , Intestino Grosso/metabolismo , Intestino Grosso/microbiologia , Camundongos , Vírus da Hepatite Murina/metabolismo , Vírus da Hepatite Murina/patogenicidade , Proteólise , SARS-CoV-2/patogenicidade , Tripsina/metabolismo , Internalização do Vírus
11.
Am J Sports Med ; 50(7): 1888-1899, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35503098

RESUMO

BACKGROUND: Hip arthroscopy for femoroacetabular impingement (FAI) in athletes, including military servicemembers, has resulted in variable outcomes. The prevalence of low back pain (LBP) and psychiatric disorders (PSYs) is high among patients undergoing hip arthroscopy. PURPOSE: To determine the effect of LBP, PSYs, and the combination of both on outcomes in servicemembers treated arthroscopically for FAI. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Between April 2016 and June 2020, a total of 108 consecutive active-duty servicemembers underwent hip arthroscopy by a single surgeon at a single military medical center. Servicemembers were grouped according to the presence of preoperative LBP (Group LBP), a PSY (Group PSY), or both (Group Both), and outcomes were compared with those of servicemembers without these comorbidities (Group None). The minimum follow-up was 6 months. The primary outcome measure was return to duty (RTD). Secondary outcomes included the Nonarthritic Hip Score (NAHS), Hip Outcome Score-Activities of Daily Living (HOS-ADL) subscale, and Hip Outcome Score-Sports (HOS-S) subscale. RESULTS: All servicemembers' final duty status was confirmed, with a mean follow-up of 2 years (range, 6 months-4.3 years). The prevalence of preoperative LBP and PSY was 27% and 39%, respectively. RTD was 59% (10/17) in Group LBP, 10% (3/30) in Group PSY, 0% (0/12) in Group Both, and 47% (23/49) in Group None. Compared with Group None, the risk of discontinuing military service was statistically higher in Group PSY (relative risk [RR], 1.70 [95% CI, 1.41-1.99]) and Group Both (RR, 1.88 [95% CI, 1.62-2.15]) but not in Group LBP (RR, 0.78 [95% CI, 0.15-1.40]). The mean preoperative secondary outcomes all significantly improved postoperatively in Group None (NAHS, 58 to 75 [P < .001]; HOS-ADL, 63 to 74 [P < .001]; HOS-S, 44 to 57 [P < .001]). Among the comorbid groups, the mean HOS-S did not significantly improve (Group LBP, 45 to 48 [P = .71]; Group PSY, 36 to 44 [P = .22]; Group Both 43 to 45 [P = .75]), and <50% of these servicemembers achieved HOS-S meaningful clinical benefit metrics. CONCLUSION: Preoperative LBP, PSY, and a combination of both negatively affected outcomes after hip arthroscopy. Preoperative counseling is crucial in setting realistic outcome expectations.


Assuntos
Impacto Femoroacetabular , Dor Lombar , Transtornos Mentais , Atividades Cotidianas , Artroscopia/métodos , Estudos de Coortes , Impacto Femoroacetabular/cirurgia , Seguimentos , Articulação do Quadril/cirurgia , Humanos , Dor Lombar/epidemiologia , Dor Lombar/etiologia , Dor Lombar/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
12.
Nature ; 606(7915): 754-760, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35614211

RESUMO

Microbial communities and their associated bioactive compounds1-3 are often disrupted in conditions such as the inflammatory bowel diseases (IBD)4. However, even in well-characterized environments (for example, the human gastrointestinal tract), more than one-third of microbial proteins are uncharacterized and often expected to be bioactive5-7. Here we systematically identified more than 340,000 protein families as potentially bioactive with respect to gut inflammation during IBD, about half of which have not to our knowledge been functionally characterized previously on the basis of homology or experiment. To validate prioritized microbial proteins, we used a combination of metagenomics, metatranscriptomics and metaproteomics to provide evidence of bioactivity for a subset of proteins that are involved in host and microbial cell-cell communication in the microbiome; for example, proteins associated with adherence or invasion processes, and extracellular von Willebrand-like factors. Predictions from high-throughput data were validated using targeted experiments that revealed the differential immunogenicity of prioritized Enterobacteriaceae pilins and the contribution of homologues of von Willebrand factors to the formation of Bacteroides biofilms in a manner dependent on mucin levels. This methodology, which we term MetaWIBELE (workflow to identify novel bioactive elements in the microbiome), is generalizable to other environmental communities and human phenotypes. The prioritized results provide thousands of candidate microbial proteins that are likely to interact with the host immune system in IBD, thus expanding our understanding of potentially bioactive gene products in chronic disease states and offering a rational compendium of possible therapeutic compounds and targets.


Assuntos
Proteínas de Bactérias , Microbioma Gastrointestinal , Genes Microbianos , Doenças Inflamatórias Intestinais , Proteínas de Bactérias/análise , Proteínas de Bactérias/genética , Doença Crônica , Microbioma Gastrointestinal/genética , Humanos , Doenças Inflamatórias Intestinais/microbiologia , Metagenômica , Proteômica , Reprodutibilidade dos Testes , Transcriptoma
13.
J Chem Phys ; 156(19): 194201, 2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35597636

RESUMO

We report pure-rotational N2-N2, N2-air, and O2-air S-branch linewidths for temperatures of 80-200 K by measuring the time-dependent decay of rotational Raman coherences in an isentropic free-jet expansion from a sonic nozzle. We recorded pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) spectra along the axial centerline of the underexpanded jet, within the barrel shock region upstream of the Mach disk. The dephasing of the pure-rotational Raman coherence was monitored using probe-time-delay scans at different axial positions in the jet, corresponding to varying local temperatures and pressures. The local temperature was obtained by fitting CARS spectra acquired at zero probe time delay, where the impact of collisions was minimal. The measured decay of each available Raman transition was fit to a dephasing constant and corrected for the local pressure, which was obtained from the CARS-measured static temperature and thermodynamic relationships for isentropic expansion from the known stagnation state. Nitrogen self-broadened transitions decayed more rapidly than those broadened in air for all temperatures, corresponding to higher Raman linewidths. In general, the measured S-branch linewidths deviated significantly in absolute and relative magnitudes from those predicted by extrapolating the modified exponential gap model to low temperatures. The temperature dependence of the Raman linewidth for each measured rotational state of nitrogen (J ≤ 10) and oxygen (N ≤ 11) was fit to a temperature-dependent power law over the measurable temperature domain (80-200 K) and extrapolated to both higher rotational states and room temperature. The measured and modeled low-temperature linewidth data provided here will aid low temperature gas-phase pressure measurements with fs/ps CARS.

14.
Opt Lett ; 47(7): 1839-1842, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35363749

RESUMO

Demonstration of broadband nanosecond coherent anti-Stokes Raman scattering (CARS) using a burst-mode-pumped noncolinear optical parametric oscillator (NOPO) has been achieved at a pulse repetition rate of 40 kHz. The NOPO is pumped with the 355-nm output of a burst-mode Nd:YAG laser at 50 mJ/pulse for 45 pulses and produces an output centered near 607 nm, with a bandwidth of 370 cm-1 at energies of 5 mJ/pulse. A planar BOXCARS phase matching scheme uses the broadband NOPO output as the Stokes beam and the narrowband 532-nm burst-mode output for the two CARS pump beams for single-laser-shot nitrogen thermometry in near adiabatic H2/air flames at temperatures up to 2200 K.

15.
Front Microbiol ; 13: 821803, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35250937

RESUMO

Isolates of the marine picocyanobacteria, Prochlorococcus and Synechococcus, are often accompanied by diverse heterotrophic "contaminating" bacteria, which can act as confounding variables in otherwise controlled experiments. Traditional microbiological methods for eliminating contaminants, such as direct streak-plating, are often unsuccessful with this particular group of microorganisms. While they will grow in pour plates, colonies often remain contaminated with heterotrophic bacteria that can migrate through the soft agar. Additionally, axenic clones of picocyanobacteria can be recovered via dilution-to-extinction in liquid medium, but the efficiency of recovery is low, often requiring large numbers of 96-well plates. Here, we detail a simple and effective protocol for rendering cultures of Synechococcus and Prochlorococcus strains free of bacterial contaminants while at the same time yielding clonal isolates. We build on the fact that co-culture with specific heterotrophs-"helper heterotrophs"-is often necessary to grow colonies of picocyanobacteria from single cells in agar. Suspecting that direct physical contact between the helper and the picocyanobacterial cells was not necessary for the "helper effect," we developed a protocol in which the helper cells are embedded in soft agar pour plates, a filter overlaid on the surface, and a picocyanobacterial culture is diluted and then spotted on top of the filter. With this approach, motile contaminants cannot swim to the colonies, and it is possible to obtain the expected number of colonies from a given input (i.e., a Poisson distribution of colonies with an expected value equal to the input number of cells), thus ensuring clonal colonies. Using this protocol, we rendered three strains of Synechococcus, two strains of Prochlorococcus, and 19 new strains of Synechococcus from coastal seawater clonal and free of heterotrophic bacteria. The simplicity of this approach should expand the repertoire of axenic picocyanobacterial strains available for controlled physiological experiments. It will also enable the study of microdiversity in populations of picocyanobacteria by facilitating large-scale isolation of picocyanobacterial clones from a single source, including direct isolation from natural seawater.

16.
Ecol Appl ; 32(2): e2503, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34870365

RESUMO

Adaptive management of large herbivores requires an understanding of how spatial-temporal fluctuations in forage biomass and quality influence animal performance. Advances in remote sensing have yielded information about the spatial-temporal dynamics of forage biomass, which in turn have informed rangeland management decisions such as stocking rate and paddock selection for free-ranging cattle. However, less is known about the spatial-temporal patterns of diet quality and their influence on large herbivore performance. This is due to infrequent concurrent ground observations of forage conditions with performance (e.g., mass gain), and previously limited satellite data at fine spatial and temporal scales. We combined multi-temporal field observations of diet quality (weekly) and mass gain (monthly) with satellite-derived phenological metrics (pseudo-daily, using data fusion and interpolation) to model daily mass gains of free-ranging yearling cattle in shortgrass steppe. We used this model to predict grazing season (mid-May to October) mass gains, a key management indicator, across 40 different paddocks grazed over a 10-year period (n = 138). We found strong relationships between diet quality and the satellite-derived phenological metrics, especially metrics related to the timing and rate of green-up and senescence. Satellite-derived diet quality estimates were strong predictors of monthly mass gains (R2  = 0.68) across a wide range of aboveground net herbaceous production. Season-long predictions of average daily gain and cattle off-mass had mean absolute errors of 8.9% and 2.9%, respectively. The model performed better temporally (across repeated observations in the same paddock) than spatially (across all paddocks within a given year), highlighting the need for accurate vegetation maps and robust field data collection across both space and time. This study demonstrates that free-ranging cattle performance in rangelands is strongly affected by diet quality, which is related to the timing of vegetation green-up and senescence. Senescing vegetation suppressed mass gains, even if adequate forage was available. The satellite-based pseudo-daily approach presented here offers new opportunities for adaptive management of large herbivores, such as identifying within-season triggers to move livestock among paddocks, predicting wildlife herd health, or timing the grazing season to better match earlier spring green-up caused by climate change and plant species invasion.


Assuntos
Dieta , Herbivoria , Animais , Bovinos , Dieta/veterinária , Gado , Estações do Ano , Fatores de Tempo
17.
J Thorac Cardiovasc Surg ; 163(6): e385-e400, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-32977969

RESUMO

OBJECTIVE: Adenosine triphosphate potassium sensitive channels provide endogenous myocardial protection via coupling of cell membrane potential to myocardial metabolism. Adenosine triphosphate potassium sensitive channel openers, such as diazoxide, mimic ischemic preconditioning, prevent cardiomyocyte swelling, preserve myocyte contractility after stress, and provide diastolic protection. We hypothesize that diazoxide combined with hyperkalemic cardioplegia provides superior myocardial protection compared with cardioplegia alone during prolonged global ischemia in a large animal model. METHODS: Twelve pigs were randomized to global ischemia for 2 hours with a single dose of cold blood (4:1) hyperkalemic cardioplegia alone (n = 6) or with diazoxide (500 µmol/L) (n = 6) and reperfused for 1 hour. Cardiac output, myocardial oxygen consumption, left ventricular developed pressure, left ventricular ejection fraction, diastolic function, myocardial troponin, myoglobin, markers of apoptosis, and left ventricular infarct size were compared. RESULTS: Four pigs in the cardioplegia alone group could not be weaned from cardiopulmonary bypass. There were no differences in myoglobin, troponin, or apoptosis between groups. Diazoxide preserved cardiac output versus control (74.5 vs 18.4 mL/kg/min, P = .01). Linear mixed regression modeling demonstrated that the addition of diazoxide to cardioplegia preserved left ventricular developed pressure by 36% (95% confidence interval, 9.9-61.5; P < .01), dP/dt max by 41% (95% confidence interval, 14.5-67.5; P < .01), and dP/dt min by 33% (95% confidence interval, 8.9-57.5; P = .01). It was also associated with higher (but not significant) myocardial oxygen consumption (3.7 vs 1.4 mL O2/min, P = .12). CONCLUSIONS: Diazoxide preserves systolic and diastolic ventricular function in a large animal model of prolonged global myocardial ischemia. Diazoxide as an adjunct to hyperkalemic cardioplegia may allow safer prolonged ischemic times during increasingly complicated cardiac procedures.


Assuntos
Diazóxido , Isquemia Miocárdica , Animais , Trifosfato de Adenosina/metabolismo , Soluções Cardioplégicas/farmacologia , Diazóxido/farmacologia , Parada Cardíaca Induzida/efeitos adversos , Parada Cardíaca Induzida/métodos , Isquemia , Mioglobina/metabolismo , Potássio/metabolismo , Canais de Potássio/metabolismo , Volume Sistólico , Suínos , Troponina , Função Ventricular Esquerda
18.
mBio ; 12(4): e0097521, 2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-34281401

RESUMO

For fecal microbiota transplantation (FMT) to be successful in immune diseases like inflammatory bowel disease, it is assumed that therapeutic microbes and their beneficial functions and immune interactions must colonize a recipient patient and persist in sufficient quantity and for a sufficient period of time to produce a clinical benefit. Few studies, however, have comprehensively profiled the colonization and persistence of transferred microbes along with the transfer of their microbial functions and interactions with the host immune system. Using 16S, metagenomic, and immunoglobulin A (IgA) sequencing, we analyzed hundreds of longitudinal microbiome samples from a randomized controlled trial of 12 patients with ulcerative colitis who received fecal transplant or placebo for 12 weeks. We uncovered diverse competitive dynamics among donor and patient strains, showing that persistence of transferred microbes is far from static. Indeed, one patient experienced a dramatic loss of donor bacteria 10 weeks into the trial, coinciding with a bloom of pathogenic bacteria and worsening symptoms. We evaluated the transfer of microbial functions, including desired ones, such as butyrate production, and unintended ones, such as antibiotic resistance. By profiling bacteria coated with IgA, we identified bacteria associated with inflammation and found that microbial interactions with the host immune system can be transferred across people, which could play a role in gut microbiome therapeutics for immune-related diseases. Our findings shed light on the colonization dynamics of gut microbes and their functions in the context of FMT to treat a complex disease-information that may provide a foundation for developing more-targeted therapeutics. IMPORTANCE Fecal microbiota transplantation (FMT)-transferring fecal microbes from a healthy donor to a sick patient-has shown promise for gut diseases such as inflammatory bowel disease. Unlike pharmaceuticals, however, fecal transplants are complex mixtures of living organisms, which must then interact with the microbes and immune system of the recipient. We sought to understand these interactions by tracking the microbes of 12 inflammatory bowel disease patients who received fecal transplants for 12 weeks. We uncovered a range of dynamics. For example, one patient experienced successful transfer of donor bacteria, only to lose them after 10 weeks. We similarly evaluated transfer of microbial functions, including how they interacted with the recipient's immune system. Our findings shed light on the colonization dynamics of gut microbes, as well as their functions in the context of FMT-information that may provide a critical foundation for the development of more-targeted therapeutics.


Assuntos
Bactérias/metabolismo , Transplante de Microbiota Fecal , Fezes/microbiologia , Microbioma Gastrointestinal , Doenças Inflamatórias Intestinais/terapia , Bactérias/classificação , Bactérias/genética , Butiratos/análise , Butiratos/metabolismo , Estudos de Coortes , Humanos , Doenças Inflamatórias Intestinais/microbiologia , Estudos Longitudinais , Metagenômica/métodos
19.
Nature ; 599(7885): 458-464, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34325466

RESUMO

Centenarians have a decreased susceptibility to ageing-associated illnesses, chronic inflammation and infectious diseases1-3. Here we show that centenarians have a distinct gut microbiome that is enriched in microorganisms that are capable of generating unique secondary bile acids, including various isoforms of lithocholic acid (LCA): iso-, 3-oxo-, allo-, 3-oxoallo- and isoallolithocholic acid. Among these bile acids, the biosynthetic pathway for isoalloLCA had not been described previously. By screening 68 bacterial isolates from the faecal microbiota of a centenarian, we identified Odoribacteraceae strains as effective producers of isoalloLCA both in vitro and in vivo. Furthermore, we found that the enzymes 5α-reductase (5AR) and 3ß-hydroxysteroid dehydrogenase (3ß-HSDH) were responsible for the production of isoalloLCA. IsoalloLCA exerted potent antimicrobial effects against Gram-positive (but not Gram-negative) multidrug-resistant pathogens, including Clostridioides difficile and Enterococcus faecium. These findings suggest that the metabolism of specific bile acids may be involved in reducing the risk of infection with pathobionts, thereby potentially contributing to the maintenance of intestinal homeostasis.


Assuntos
Bactérias/metabolismo , Vias Biossintéticas , Centenários , Microbioma Gastrointestinal , Ácido Litocólico/análogos & derivados , Ácido Litocólico/biossíntese , 3-Hidroxiesteroide Desidrogenases/metabolismo , Idoso de 80 Anos ou mais , Animais , Antibacterianos/biossíntese , Antibacterianos/metabolismo , Bactérias/classificação , Bactérias/enzimologia , Bactérias/isolamento & purificação , Colestenona 5 alfa-Redutase/metabolismo , Fezes/química , Fezes/microbiologia , Feminino , Bactérias Gram-Positivas/metabolismo , Humanos , Ácido Litocólico/metabolismo , Masculino , Camundongos , Simbiose
20.
Opt Lett ; 46(9): 2160-2163, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33929443

RESUMO

A high-speed temperature diagnostic based on spontaneous Raman scattering (SRS) was demonstrated using a pulse-burst laser. The technique was first benchmarked in near-adiabatic ${{\rm H}_2} \text{-} {\rm air}$ flames at a data-acquisition rate of 5 kHz using an integrated pulse energy of 1.0 J per realization. Both the measurement precision and accuracy in the flame were within 3% of adiabatic predictions. This technique was then evaluated in a challenging free-piston shock tube environment operated at a shock Mach number of 3.5. SRS thermometry resolved the temperature in post-incident and post-reflected shock flows at a repetition rate of 3 kHz and clearly showed cooling associated with driver expansion waves. Collectively, this Letter represents a major advancement for SRS in impulsive facilities, which had previously been limited to steady state regions or single-shot acquisition.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...