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1.
Nature ; 592(7855): 517-523, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33883733

RESUMO

Palaeorecords suggest that the climate system has tipping points, where small changes in forcing cause substantial and irreversible alteration to Earth system components called tipping elements. As atmospheric greenhouse gas concentrations continue to rise as a result of fossil fuel burning, human activity could also trigger tipping, and the impacts would be difficult to adapt to. Previous studies report low global warming thresholds above pre-industrial conditions for key tipping elements such as ice-sheet melt. If so, high contemporary rates of warming imply that exceeding these thresholds is almost inevitable, which is widely assumed to mean that we are now committed to suffering these tipping events. Here we show that this assumption may be flawed, especially for slow-onset tipping elements (such as the collapse of the Atlantic Meridional Overturning Circulation) in our rapidly changing climate. Recently developed theory indicates that a threshold may be temporarily exceeded without prompting a change of system state, if the overshoot time is short compared to the effective timescale of the tipping element. To demonstrate this, we consider transparently simple models of tipping elements with prescribed thresholds, driven by global warming trajectories that peak before returning to stabilize at a global warming level of 1.5 degrees Celsius above the pre-industrial level. These results highlight the importance of accounting for timescales when assessing risks associated with overshooting tipping point thresholds.


Assuntos
Clima , Aquecimento Global/prevenção & controle , Modelos Teóricos , Animais , Atividades Humanas , Humanos , Camada de Gelo/química , Reprodutibilidade dos Testes , Medição de Risco , Fatores de Tempo , Movimentos da Água
2.
Glob Chang Biol ; 30(3): e17188, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38462677

RESUMO

Vegetation and precipitation are known to fundamentally influence each other. However, this interdependence is not fully represented in climate models because the characteristics of land surface (canopy) conductance to water vapor and CO2 are determined independently of precipitation. Working within a coupled atmosphere and land modelling framework (CAM6/CLM5; coupled Community Atmosphere Model v6/Community Land Model v5), we have developed a new theoretical approach to characterizing land surface conductance by explicitly linking its dynamic properties to local precipitation, a robust proxy for moisture available to vegetation. This will enable regional surface conductance characteristics to shift fluidly with climate change in simulations, consistent with general principles of co-evolution of vegetation and climate. Testing within the CAM6/CLM5 framework shows that climate simulations incorporating the new theory outperform current default configurations across several error metrics for core output variables when measured against observational data. In climate simulations for the end of this century the new, adaptive stomatal conductance scheme provides a revised prognosis for average and extreme temperatures over several large regions, with increased primary productivity through central and east Asia, and higher rainfall through North Africa and the Middle East. The new projections also reveal more frequent heatwaves than originally estimated for the south-eastern US and sub-Saharan Africa but less frequent heatwaves across east Europe and northeast Asia. These developments have implications for evaluating food security and risks from extreme temperatures in areas that are vulnerable to climate change.


Assuntos
Atmosfera , Ecossistema , Previsões , Temperatura Alta , África Subsaariana , Mudança Climática
3.
J Chem Inf Model ; 64(7): 2695-2704, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38293736

RESUMO

Predicting compound activity in assays is a long-standing challenge in drug discovery. Computational models based on compound-induced gene expression signatures from a single profiling assay have shown promise toward predicting compound activity in other, seemingly unrelated, assays. Applications of such models include predicting mechanisms-of-action (MoA) for phenotypic hits, identifying off-target activities, and identifying polypharmacologies. Here, we introduce transcriptomics-to-activity transformer (TAT) models that leverage gene expression profiles observed over compound treatment at multiple concentrations to predict the compound activity in other biochemical or cellular assays. We built TAT models based on gene expression data from a RASL-seq assay to predict the activity of 2692 compounds in 262 dose-response assays. We obtained useful models for 51% of the assays, as determined through a realistic held-out set. Prospectively, we experimentally validated the activity predictions of a TAT model in a malaria inhibition assay. With a 63% hit rate, TAT successfully identified several submicromolar malaria inhibitors. Our results thus demonstrate the potential of transcriptomic responses over compound concentration and the TAT modeling framework as a cost-efficient way to identify the bioactivities of promising compounds across many assays.


Assuntos
Aprendizado Profundo , Malária , Humanos , Transcriptoma , Descoberta de Drogas/métodos , Perfilação da Expressão Gênica
4.
Nature ; 553(7688): 319-322, 2018 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-29345639

RESUMO

Equilibrium climate sensitivity (ECS) remains one of the most important unknowns in climate change science. ECS is defined as the global mean warming that would occur if the atmospheric carbon dioxide (CO2) concentration were instantly doubled and the climate were then brought to equilibrium with that new level of CO2. Despite its rather idealized definition, ECS has continuing relevance for international climate change agreements, which are often framed in terms of stabilization of global warming relative to the pre-industrial climate. However, the 'likely' range of ECS as stated by the Intergovernmental Panel on Climate Change (IPCC) has remained at 1.5-4.5 degrees Celsius for more than 25 years. The possibility of a value of ECS towards the upper end of this range reduces the feasibility of avoiding 2 degrees Celsius of global warming, as required by the Paris Agreement. Here we present a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC 'likely' range) of 2.2-3.4 degrees Celsius. Our approach is to focus on the variability of temperature about long-term historical warming, rather than on the warming trend itself. We use an ensemble of climate models to define an emergent relationship between ECS and a theoretically informed metric of global temperature variability. This metric of variability can also be calculated from observational records of global warming, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.


Assuntos
Aquecimento Global/estatística & dados numéricos , Modelos Teóricos , Temperatura , Dióxido de Carbono/análise , Aquecimento Global/história , História do Século XIX , História do Século XX , História do Século XXI , Observação , Probabilidade
5.
Nature ; 538(7626): 499-501, 2016 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-27680704

RESUMO

Uncertainties in the response of vegetation to rising atmospheric CO2 concentrations contribute to the large spread in projections of future climate change. Climate-carbon cycle models generally agree that elevated atmospheric CO2 concentrations will enhance terrestrial gross primary productivity (GPP). However, the magnitude of this CO2 fertilization effect varies from a 20 per cent to a 60 per cent increase in GPP for a doubling of atmospheric CO2 concentrations in model studies. Here we demonstrate emergent constraints on large-scale CO2 fertilization using observed changes in the amplitude of the atmospheric CO2 seasonal cycle that are thought to be the result of increasing terrestrial GPP. Our comparison of atmospheric CO2 measurements from Point Barrow in Alaska and Cape Kumukahi in Hawaii with historical simulations of the latest climate-carbon cycle models demonstrates that the increase in the amplitude of the CO2 seasonal cycle at both measurement sites is consistent with increasing annual mean GPP, driven in part by climate warming, but with differences in CO2 fertilization controlling the spread among the model trends. As a result, the relationship between the amplitude of the CO2 seasonal cycle and the magnitude of CO2 fertilization of GPP is almost linear across the entire ensemble of models. When combined with the observed trends in the seasonal CO2 amplitude, these relationships lead to consistent emergent constraints on the CO2 fertilization of GPP. Overall, we estimate a GPP increase of 37 ± 9 per cent for high-latitude ecosystems and 32 ± 9 per cent for extratropical ecosystems under a doubling of atmospheric CO2 concentrations on the basis of the Point Barrow and Cape Kumukahi records, respectively.


Assuntos
Atmosfera/química , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Mudança Climática , Modelos Teóricos , Fotossíntese , Estações do Ano , Incerteza , Alaska , Ciclo do Carbono , Ecossistema , Havaí
6.
Epilepsy Behav ; 124: 108354, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34628090

RESUMO

PURPOSE: To review the standard of clinical care of people with epilepsy (PWE) attending UK general practice after epilepsy was removed from the Quality and Outcomes Framework (QOF) in 2014. METHOD: The case notes of 324 people were reviewed against standards based on National Institute for Health and Care Excellence (NICE), Drug Safety Unit (DSU), and Medicines and Healthcare products Regulatory Agency (MHRA) guidelines. RESULTS: Annual face-to-face review fell significantly (p = 0.021) after the removal of epilepsy from QOF in 2014. Clinical Commissioning Group (CCG) downloaded review rates fell significantly from 95% in 2010 to only 14% in 2016. One hundred and twenty seven (39%) people had seen their GP, and108 (33%) had not seen any doctor, in the past year. One hundred and seventy three (53%) were under specialist care. Forty nine percent not under specialist care had poor control. Two hundred and fifty four (78%) people were on ASM (Anti-Seizure Medication) associated with poor bone health, of these 41 (16%) were prescribed vitamin D. Fourteen women of childbearing age were taking sodium valproate, of whom only 5 (36%) had written confirmation of being counseled of the associated risks. Fifty six (17%) people were non-complaint with prescription collection, of which 66% had documented poor control. There was a discrepancy between actual face-to-face review rates and the review rates the CCG collected. CONCLUSION: This study reveals poor annual review rates for PWE in UK primary care, which have fallen further since the removal of epilepsy from QOF. Unmet needs persist for people with poorly controlled epilepsy not under specialist care, bone health, and the care of women of child bearing age. This study, along with previous work, brings into question the concept of shared care for PWE. Clinical Commissioning Groups should consider investing in the training and employment of GPwSIe (GP with Special Interest in epilepsy) and ENS (Epilepsy Nurse Specialists) to work in the community. The Government should examine re-introducing epilepsy back into QOF with measurable clinical targets and adequate remuneration.


Assuntos
Epilepsia , Medicina Geral , Epilepsia/epidemiologia , Epilepsia/terapia , Feminino , Humanos , Atenção Primária à Saúde , Reino Unido/epidemiologia , Ácido Valproico
7.
Rheumatol Int ; 41(7): 1209-1219, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33987709

RESUMO

The aims of this systematic review and meta-analysis were to describe prevalence of cardiovascular disease in gout, compare these results with non-gout controls and consider whether there were differences according to geography. PubMed, Scopus and Web of Science were systematically searched for studies reporting prevalence of any cardiovascular disease in a gout population. Studies with non-representative sampling, where a cohort had been used in another study, small sample size (< 100) and where gout could not be distinguished from other rheumatic conditions were excluded, as were reviews, editorials and comments. Where possible meta-analysis was performed using random-effect models. Twenty-six studies comprising 949,773 gout patients were included in the review. Pooled prevalence estimates were calculated for five cardiovascular diseases: myocardial infarction (2.8%; 95% confidence interval (CI)s 1.6, 5.0), heart failure (8.7%; 95% CI 2.9, 23.8), venous thromboembolism (2.1%; 95% CI 1.2, 3.4), cerebrovascular accident (4.3%; 95% CI 1.8, 9.7) and hypertension (63.9%; 95% CI 24.5, 90.6). Sixteen studies reported comparisons with non-gout controls, illustrating an increased risk in the gout group across all cardiovascular diseases. There were no identifiable reliable patterns when analysing the results by country. Cardiovascular diseases are more prevalent in patients with gout and should prompt vigilance from clinicians to the need to assess and stratify cardiovascular risk. Future research is needed to investigate the link between gout, hyperuricaemia and increased cardiovascular risk and also to establish a more thorough picture of prevalence for less common cardiovascular diseases.


Assuntos
Doenças Cardiovasculares/epidemiologia , Gota/epidemiologia , Comorbidade , Humanos , Incidência , Prevalência
8.
J Virol ; 93(9)2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30787147

RESUMO

Covalently closed circular DNA (cccDNA) forms the basis for replication and persistence of hepatitis B virus (HBV) in the chronically infected liver. We have previously shown that viral transcription is subject to regulation by posttranslational modifications (PTMs) of histone proteins bound to cccDNA through analysis of de novo HBV-infected cell lines. We now report the successful adaptation of this chromatin immunoprecipitation sequencing (ChIPseq) approach for analysis of fine-needle patient liver biopsy specimens to investigate the role of histone PTMs in chronically HBV-infected patients. Using 18 specimens from patients in different stages of chronic HBV infection, our work shows that the profile of histone PTMs in chronic infection is more nuanced than previously observed in in vitro models of acute infection. In line with our previous findings, we find that the majority of HBV-derived sequences are associated with the activating histone PTM H3K4me3. However, we show a striking interpatient variability of its deposition in this patient cohort correlated with viral transcription and patient HBV early antigen (HBeAg) status. Unexpectedly, we detected deposition of the classical inhibitory histone PTM H3K9me3 on HBV-DNA in around half of the patient biopsy specimens, which could not be linked to reduced levels of viral transcripts. Our results show that current in vitro models are unable to fully recapitulate the complex epigenetic landscape of chronic HBV infection observed in vivo and demonstrate that fine-needle liver biopsy specimens can provide sufficient material to further investigate the interaction of viral and host proteins on HBV-DNA.IMPORTANCE Hepatitis B virus (HBV) is a major global health concern, chronically infecting millions of patients and contributing to a rising burden of liver disease. The viral genome forms the basis for chronic infection and has been shown to be subject to regulation by epigenetic mechanisms, such as posttranslational modification of histone proteins. Here, we confirm and expand on previous results by adapting a high-resolution technique for analysis of histone modifications for use with patient-derived fine-needle liver biopsy specimens. Our work highlights that the situation in vivo is more complex than predicted by current in vitro models, for example, by suggesting a novel, noncanonical role of the histone modification H3K9me3 in the HBV life cycle. Importantly, enabling the use of fine-needle liver biopsy specimens for such high-resolution analyses may facilitate further research into the epigenetic regulation of the HBV genome.


Assuntos
DNA Viral/metabolismo , Vírus da Hepatite B/metabolismo , Hepatite B Crônica , Histonas/metabolismo , Fígado , Processamento de Proteína Pós-Traducional , Adolescente , Adulto , Idoso , Biópsia por Agulha Fina , Feminino , Células Hep G2 , Hepatite B Crônica/metabolismo , Hepatite B Crônica/patologia , Humanos , Fígado/metabolismo , Fígado/patologia , Masculino , Pessoa de Meia-Idade
9.
New Phytol ; 226(6): 1622-1637, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-31916258

RESUMO

Land surface models (LSMs) typically use empirical functions to represent vegetation responses to soil drought. These functions largely neglect recent advances in plant ecophysiology that link xylem hydraulic functioning with stomatal responses to climate. We developed an analytical stomatal optimization model based on xylem hydraulics (SOX) to predict plant responses to drought. Coupling SOX to the Joint UK Land Environment Simulator (JULES) LSM, we conducted a global evaluation of SOX against leaf- and ecosystem-level observations. SOX simulates leaf stomatal conductance responses to climate for woody plants more accurately and parsimoniously than the existing JULES stomatal conductance model. An ecosystem-level evaluation at 70 eddy flux sites shows that SOX decreases the sensitivity of gross primary productivity (GPP) to soil moisture, which improves the model agreement with observations and increases the predicted annual GPP by 30% in relation to JULES. SOX decreases JULES root-mean-square error in GPP by up to 45% in evergreen tropical forests, and can simulate realistic patterns of canopy water potential and soil water dynamics at the studied sites. SOX provides a parsimonious way to incorporate recent advances in plant hydraulics and optimality theory into LSMs, and an alternative to empirical stress factors.


Assuntos
Ecossistema , Xilema , Clima , Secas , Florestas , Folhas de Planta , Água
10.
Nature ; 506(7487): 212-5, 2014 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-24463514

RESUMO

Earth system models project that the tropical land carbon sink will decrease in size in response to an increase in warming and drought during this century, probably causing a positive climate feedback. But available data are too limited at present to test the predicted changes in the tropical carbon balance in response to climate change. Long-term atmospheric carbon dioxide data provide a global record that integrates the interannual variability of the global carbon balance. Multiple lines of evidence demonstrate that most of this variability originates in the terrestrial biosphere. In particular, the year-to-year variations in the atmospheric carbon dioxide growth rate (CGR) are thought to be the result of fluctuations in the carbon fluxes of tropical land areas. Recently, the response of CGR to tropical climate interannual variability was used to put a constraint on the sensitivity of tropical land carbon to climate change. Here we use the long-term CGR record from Mauna Loa and the South Pole to show that the sensitivity of CGR to tropical temperature interannual variability has increased by a factor of 1.9 ± 0.3 in the past five decades. We find that this sensitivity was greater when tropical land regions experienced drier conditions. This suggests that the sensitivity of CGR to interannual temperature variations is regulated by moisture conditions, even though the direct correlation between CGR and tropical precipitation is weak. We also find that present terrestrial carbon cycle models do not capture the observed enhancement in CGR sensitivity in the past five decades. More realistic model predictions of future carbon cycle and climate feedbacks require a better understanding of the processes driving the response of tropical ecosystems to drought and warming.


Assuntos
Ciclo do Carbono/fisiologia , Temperatura , Clima Tropical , Regiões Antárticas , Atmosfera/química , Carbono/análise , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Sequestro de Carbono , Secas , Ecossistema , Aquecimento Global , Havaí , História do Século XX , História do Século XXI , Umidade , Modelos Teóricos , Chuva
11.
J Neurosci ; 38(43): 9186-9201, 2018 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-30181139

RESUMO

The putative cache (Ca2+ channel and chemotaxis receptor) domain containing 1 (CACHD1) protein has predicted structural similarities to members of the α2δ voltage-gated Ca2+ channel auxiliary subunit family. CACHD1 mRNA and protein were highly expressed in the male mammalian CNS, in particular in the thalamus, hippocampus, and cerebellum, with a broadly similar tissue distribution to CaV3 subunits, in particular CaV3.1. In expression studies, CACHD1 increased cell-surface localization of CaV3.1, and these proteins were in close proximity at the cell surface, consistent with the formation of CACHD1-CaV3.1 complexes. In functional electrophysiological studies, coexpression of human CACHD1 with CaV3.1, CaV3.2, and CaV3.3 caused a significant increase in peak current density and corresponding increases in maximal conductance. By contrast, α2δ-1 had no effect on peak current density or maximal conductance in CaV3.1, CaV3.2, or CaV3.3. A comparison of CACHD1-mediated increases in CaV3.1 current density and gating currents revealed an increase in channel open probability. In hippocampal neurons from male and female embryonic day 19 rats, CACHD1 overexpression increased CaV3-mediated action potential firing frequency and neuronal excitability. These data suggest that CACHD1 is structurally an α2δ-like protein that functionally modulates CaV3 voltage-gated calcium channel activity.SIGNIFICANCE STATEMENT This is the first study to characterize the Ca2+ channel and chemotaxis receptor domain containing 1 (CACHD1) protein. CACHD1 is widely expressed in the CNS, in particular in the thalamus, hippocampus, and cerebellum. CACHD1 distribution is similar to that of low voltage-activated (CaV3, T-type) calcium channels, in particular to CaV3.1, a protein that regulates neuronal excitability and is a potential therapeutic target in conditions such as epilepsy and pain. CACHD1 is structurally an α2δ-like protein that functionally increases CaV3 calcium current. CACHD1 increases the presence of CaV3.1 at the cell surface, forms complexes with CaV3.1 at the cell surface, and causes an increase in channel open probability. In hippocampal neurons, CACHD1 causes increases in neuronal firing. Thus, CACHD1 represents a novel protein that modulates CaV3 activity.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo T/biossíntese , Hipocampo/metabolismo , Proteínas de Membrana/metabolismo , Animais , Canais de Cálcio Tipo L/química , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo T/química , Canais de Cálcio Tipo T/genética , Feminino , Células HEK293 , Humanos , Masculino , Proteínas de Membrana/química , Proteínas de Membrana/genética , Ratos , Ratos Wistar
12.
Rep Prog Phys ; 82(11): 116201, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31185458

RESUMO

We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of standard model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the [Formula: see text]m scale up to the Big Bang Nucleosynthesis limit of [Formula: see text] m. Neutral LLPs with lifetimes above [Formula: see text]100 m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. We study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC, assuming backgrounds can be rejected as expected. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top-down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector.

13.
Hum Mol Genet ; 26(7): 1391-1406, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28199695

RESUMO

Understanding the interaction between humans and mosquitoes is a critical area of study due to the phenomenal burdens on public health from mosquito-transmitted diseases. In this study, we conducted the first genome-wide association studies (GWAS) of self-reported mosquito bite reaction size (n = 84,724), itchiness caused by bites (n = 69,057), and perceived attractiveness to mosquitoes (n = 16,576). In total, 15 independent significant (P < 5×10-8) associations were identified. These loci were enriched for immunity-related genes that are involved in multiple cytokine signalling pathways. We also detected suggestive enrichment of these loci in enhancer regions that are active in stimulated T-cells, as well as within loci previously identified as controlling central memory T-cell levels. Egger regression analysis between the traits suggests that perception of itchiness and attractiveness to mosquitoes is driven, at least in part, by the genetic determinants of bite reaction size.Our findings illustrate the complex genetic and immunological landscapes underpinning human interactions with mosquitoes.


Assuntos
Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Mordeduras e Picadas de Insetos/genética , Prurido/genética , Animais , Culicidae/genética , Culicidae/patogenicidade , Genótipo , Humanos , Mordeduras e Picadas de Insetos/patologia , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Prurido/patologia , Autorrelato , Linfócitos T/imunologia , Linfócitos T/metabolismo
14.
Nature ; 563(7729): E10-E15, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30382204
15.
Nature ; 500(7462): 327-30, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23883935

RESUMO

Evidence from Greenland ice cores shows that year-to-year temperature variability was probably higher in some past cold periods, but there is considerable interest in determining whether global warming is increasing climate variability at present. This interest is motivated by an understanding that increased variability and resulting extreme weather conditions may be more difficult for society to adapt to than altered mean conditions. So far, however, in spite of suggestions of increased variability, there is considerable uncertainty as to whether it is occurring. Here we show that although fluctuations in annual temperature have indeed shown substantial geographical variation over the past few decades, the time-evolving standard deviation of globally averaged temperature anomalies has been stable. A feature of the changes has been a tendency for many regions of low variability to experience increases, which might contribute to the perception of increased climate volatility. The normalization of temperature anomalies creates the impression of larger relative overall increases, but our use of absolute values, which we argue is a more appropriate approach, reveals little change. Regionally, greater year-to-year changes recently occurred in much of North America and Europe. Many climate models predict that total variability will ultimately decrease under high greenhouse gas concentrations, possibly associated with reductions in sea-ice cover. Our findings contradict the view that a warming world will automatically be one of more overall climatic variation.


Assuntos
Mudança Climática , Simulação por Computador , Temperatura , Aquecimento Global , Camada de Gelo , Estações do Ano
16.
Nature ; 494(7437): 341-4, 2013 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-23389447

RESUMO

The release of carbon from tropical forests may exacerbate future climate change, but the magnitude of the effect in climate models remains uncertain. Coupled climate-carbon-cycle models generally agree that carbon storage on land will increase as a result of the simultaneous enhancement of plant photosynthesis and water use efficiency under higher atmospheric CO(2) concentrations, but will decrease owing to higher soil and plant respiration rates associated with warming temperatures. At present, the balance between these effects varies markedly among coupled climate-carbon-cycle models, leading to a range of 330 gigatonnes in the projected change in the amount of carbon stored on tropical land by 2100. Explanations for this large uncertainty include differences in the predicted change in rainfall in Amazonia and variations in the responses of alternative vegetation models to warming. Here we identify an emergent linear relationship, across an ensemble of models, between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO(2) to tropical temperature anomalies. Combined with contemporary observations of atmospheric CO(2) concentration and tropical temperature, this relationship provides a tight constraint on the sensitivity of tropical land carbon to climate change. We estimate that over tropical land from latitude 30° north to 30° south, warming alone will release 53 ± 17 gigatonnes of carbon per kelvin. Compared with the unconstrained ensemble of climate-carbon-cycle projections, this indicates a much lower risk of Amazon forest dieback under CO(2)-induced climate change if CO(2) fertilization effects are as large as suggested by current models. Our study, however, also implies greater certainty that carbon will be lost from tropical land if warming arises from reductions in aerosols or increases in other greenhouse gases.


Assuntos
Ciclo do Carbono/fisiologia , Dióxido de Carbono/metabolismo , Mudança Climática , Modelos Teóricos , Árvores/metabolismo , Clima Tropical , Dióxido de Carbono/análise , Respiração Celular , Fotossíntese , Chuva , Temperatura , Incerteza
17.
Artigo em Inglês | MEDLINE | ID: mdl-30061293

RESUMO

The monobactam scaffold is attractive for the development of new agents to treat infections caused by drug-resistant Gram-negative bacteria because it is stable to metallo-ß-lactamases (MBLs). However, the clinically used monobactam aztreonam lacks stability to serine ß-lactamases (SBLs) that are often coexpressed with MBLs. LYS228 is stable to MBLs and most SBLs. LYS228 bound purified Escherichia coli penicillin binding protein 3 (PBP3) similarly to aztreonam (derived acylation rate/equilibrium dissociation constant [k2/Kd ] of 367,504 s-1 M-1 and 409,229 s-1 M-1, respectively) according to stopped-flow fluorimetry. A gel-based assay showed that LYS228 bound mainly to E. coli PBP3, with weaker binding to PBP1a and PBP1b. Exposing E. coli cells to LYS228 caused filamentation consistent with impaired cell division. No single-step mutants were selected from 12 Enterobacteriaceae strains expressing different classes of ß-lactamases at 8× the MIC of LYS228 (frequency, <2.5 × 10-9). At 4× the MIC, mutants were selected from 2 of 12 strains at frequencies of 1.8 × 10-7 and 4.2 × 10-9 LYS228 MICs were ≤2 µg/ml against all mutants. These frequencies compared favorably to those for meropenem and tigecycline. Mutations decreasing LYS228 susceptibility occurred in ramR and cpxA (Klebsiella pneumoniae) and baeS (E. coli and K. pneumoniae). Susceptibility of E. coli ATCC 25922 to LYS228 decreased 256-fold (MIC, 0.125 to 32 µg/ml) after 20 serial passages. Mutants accumulated mutations in ftsI (encoding the target, PBP3), baeR, acrD, envZ, sucB, and rfaI These results support the continued development of LYS228, which is currently undergoing phase II clinical trials for complicated intraabdominal infection and complicated urinary tract infection (registered at ClinicalTrials.gov under identifiers NCT03377426 and NCT03354754).


Assuntos
Antibacterianos/farmacologia , Escherichia coli/enzimologia , Escherichia coli/genética , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Monobactamas/farmacologia , Aztreonam/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Mutação/genética , beta-Lactamases/genética
18.
Lancet ; 389(10074): 1151-1164, 2017 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-27856085

RESUMO

The Lancet Countdown: tracking progress on health and climate change is an international, multidisciplinary research collaboration between academic institutions and practitioners across the world. It follows on from the work of the 2015 Lancet Commission, which concluded that the response to climate change could be "the greatest global health opportunity of the 21st century". The Lancet Countdown aims to track the health impacts of climate hazards; health resilience and adaptation; health co-benefits of climate change mitigation; economics and finance; and political and broader engagement. These focus areas form the five thematic working groups of the Lancet Countdown and represent different aspects of the complex association between health and climate change. These thematic groups will provide indicators for a global overview of health and climate change; national case studies highlighting countries leading the way or going against the trend; and engagement with a range of stakeholders. The Lancet Countdown ultimately aims to report annually on a series of indicators across these five working groups. This paper outlines the potential indicators and indicator domains to be tracked by the collaboration, with suggestions on the methodologies and datasets available to achieve this end. The proposed indicator domains require further refinement, and mark the beginning of an ongoing consultation process-from November, 2016 to early 2017-to develop these domains, identify key areas not currently covered, and change indicators where necessary. This collaboration will actively seek to engage with existing monitoring processes, such as the UN Sustainable Development Goals and WHO's climate and health country profiles. The indicators will also evolve over time through ongoing collaboration with experts and a range of stakeholders, and be dependent on the emergence of new evidence and knowledge. During the course of its work, the Lancet Countdown will adopt a collaborative and iterative process, which aims to complement existing initiatives, welcome engagement with new partners, and be open to developing new research projects on health and climate change.


Assuntos
Mudança Climática , Saúde Global , Política de Saúde , Conservação dos Recursos Naturais , Biomarcadores Ambientais , Humanos
19.
BMC Med Genet ; 19(1): 124, 2018 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-30037327

RESUMO

BACKGROUND: Individuals with an extremely rare inherited condition, termed Congenital Insensitivity to Pain (CIP), do not feel pain in response to noxious stimuli. Variants in SCN9A, encoding the transmembrane voltage-gated sodium channel Nav1.7, have previously been reported in subjects with CIP accompanied by anosmia, which are typically transmitted in a recessive pattern. Functional characterisations of some of these SCN9A mutations show that they result in complete loss-of-function of Nav1.7. METHODS: In a consanguineous family we performed whole exome sequencing of three members who have a diagnosis of CIP and one unaffected family member. The functional effects of the segregating variant in SCN9A were determined using patch clamp electrophysiology in human embryonic kidney (HEK) 293 cells transfected with the variant. RESULTS: We found that each CIP subject was homozygous for a putatively nonsense variant, R1488*, in SCN9A. This variant was reported elsewhere in a subject with CIP, though the functional effect was not determined. Using electrophysiology, we confirm that this variant results in a complete loss-of-function of Nav1.7. CONCLUSIONS: We confirm through electrophysiological analysis that this R1488* variant in SCN9A results in complete loss-of-function of Nav1.7, which is consistent with reports on other variants in this gene in subjects with CIP.


Assuntos
Canal de Sódio Disparado por Voltagem NAV1.7/genética , Linhagem Celular , Códon sem Sentido/genética , Fenômenos Eletrofisiológicos/genética , Feminino , Células HEK293 , Humanos , Masculino , Mutação/genética , Linhagem , Sequenciamento do Exoma/métodos
20.
New Phytol ; 218(4): 1462-1477, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29635689

RESUMO

Plant temperature responses vary geographically, reflecting thermally contrasting habitats and long-term species adaptations to their climate of origin. Plants also can acclimate to fast temporal changes in temperature regime to mitigate stress. Although plant photosynthetic responses are known to acclimate to temperature, many global models used to predict future vegetation and climate-carbon interactions do not include this process. We quantify the global and regional impacts of biogeographical variability and thermal acclimation of temperature response of photosynthetic capacity on the terrestrial carbon (C) cycle between 1860 and 2100 within a coupled climate-carbon cycle model, that emulates 22 global climate models. Results indicate that inclusion of biogeographical variation in photosynthetic temperature response is most important for present-day and future C uptake, with increasing importance of thermal acclimation under future warming. Accounting for both effects narrows the range of predictions of the simulated global land C storage in 2100 across climate projections (29% and 43% globally and in the tropics, respectively). Contrary to earlier studies, our results suggest that thermal acclimation of photosynthetic capacity makes tropical and temperate C less vulnerable to warming, but reduces the warming-induced C uptake in the boreal region under elevated CO2 .


Assuntos
Carbono/metabolismo , Geografia , Fotossíntese , Temperatura , Dióxido de Carbono/metabolismo , Simulação por Computador , Ecossistema , Luz , Modelos Teóricos , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Solo , Fatores de Tempo
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