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BACKGROUND: Whether treatment of gestational diabetes before 20 weeks' gestation improves maternal and infant health is unclear. METHODS: We randomly assigned, in a 1:1 ratio, women between 4 weeks' and 19 weeks 6 days' gestation who had a risk factor for hyperglycemia and a diagnosis of gestational diabetes (World Health Organization 2013 criteria) to receive immediate treatment for gestational diabetes or deferred or no treatment, depending on the results of a repeat oral glucose-tolerance test [OGTT] at 24 to 28 weeks' gestation (control). The trial included three primary outcomes: a composite of adverse neonatal outcomes (birth at <37 weeks' gestation, birth trauma, birth weight of ≥4500 g, respiratory distress, phototherapy, stillbirth or neonatal death, or shoulder dystocia), pregnancy-related hypertension (preeclampsia, eclampsia, or gestational hypertension), and neonatal lean body mass. RESULTS: A total of 802 women underwent randomization; 406 were assigned to the immediate-treatment group and 396 to the control group; follow-up data were available for 793 women (98.9%). An initial OGTT was performed at a mean (±SD) gestation of 15.6±2.5 weeks. An adverse neonatal outcome event occurred in 94 of 378 women (24.9%) in the immediate-treatment group and in 113 of 370 women (30.5%) in the control group (adjusted risk difference, -5.6 percentage points; 95% confidence interval [CI], -10.1 to -1.2). Pregnancy-related hypertension occurred in 40 of 378 women (10.6%) in the immediate-treatment group and in 37 of 372 women (9.9%) in the control group (adjusted risk difference, 0.7 percentage points; 95% CI, -1.6 to 2.9). The mean neonatal lean body mass was 2.86 kg in the immediate-treatment group and 2.91 kg in the control group (adjusted mean difference, -0.04 kg; 95% CI, -0.09 to 0.02). No between-group differences were observed with respect to serious adverse events associated with screening and treatment. CONCLUSIONS: Immediate treatment of gestational diabetes before 20 weeks' gestation led to a modestly lower incidence of a composite of adverse neonatal outcomes than no immediate treatment; no material differences were observed for pregnancy-related hypertension or neonatal lean body mass. (Funded by the National Health and Medical Research Council and others; TOBOGM Australian New Zealand Clinical Trials Registry number, ACTRN12616000924459.).
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Diabetes Gestacional , Feminino , Humanos , Recém-Nascido , Gravidez , Austrália , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/terapia , Hipertensão/etiologia , Pré-Eclâmpsia/epidemiologia , Pré-Eclâmpsia/etiologia , Pré-Eclâmpsia/prevenção & controle , Resultado da Gravidez , Natimorto , Primeiro Trimestre da GravidezRESUMO
OBJECTIVE: To identify factors associated with neonatal respiratory distress (NRD) in early Gestational diabetes mellitus (eGDM). DESIGN: Nested case-control analysis of the TOBOGM trial. SETTING: Seventeen hospitals: Australia, Sweden, Austria and India. POPULATION: Pregnant women, <20 weeks' gestation, singleton, GDM risk factors. METHODS: Women with GDM risk factors completed an oral glucose tolerance test (OGTT) before 20 weeks: those with eGDM (WHO-2013 criteria) were randomised to immediate or deferred GDM treatment. Logistic regression compared pregnancies with/without NRD, and in pregnancies with NRD, those with/without high-dependency nursery admission for ≤24 h with those admitted for >24 h. Comparisons were adjusted for age, pre-pregnancy body mass index, ethnicity, smoking, primigravity, education and site. Adjusted odds ratios (95% CI) are reported. MAIN OUTCOME MEASURES: NRD definition: ≥4 h of respiratory support (supplemental oxygen or supported ventilation) postpartum. Respiratory distress syndrome (RDS): Supported ventilation and ≥24 h nursery stay. RESULTS: Ninety-nine (12.5%) of 793 infants had NRD; incidence halved (0.50, 0.31-0.79) if GDM treatment was started early. NRD was associated with Caesarean section (2.31, 1.42-3.76), large for gestational age (LGA) (1.83, 1.09-3.08) and shorter gestation (0.95, 0.93-0.97 per day longer). Among NRD infants, >24 h nursery-stay was associated with higher OGTT 1-h glucose (1.38, 1.08-1.76 per mmol/L). Fifteen (2.0%) infants had RDS. CONCLUSIONS: Identifying and treating eGDM reduces NRD risk. NRD is more likely with Caesarean section, LGA and shorter gestation. Further studies are needed to understand the mechanisms behind this eGDM complication and any long-term effects.
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The cytochrome P450 (CYP) superfamily of heme monooxygenases has demonstrated ability to facilitate hydroxylation, desaturation, sulfoxidation, epoxidation, heteroatom dealkylation, and carbon-carbon bond formation and cleavage (lyase) reactions. Seeking to study the carbon-carbon cleavage reaction of α-hydroxy ketones in mechanistic detail using a microbial P450, we synthesized α-hydroxy ketone probes based on the physiological substrate for a well-characterized benzoic acid metabolizing P450, CYP199A4. After observing low activity with wild-type CYP199A4, subsequent assays with an F182L mutant demonstrated enzyme-dependent C-C bond cleavage toward one of the α-hydroxy ketones. This C-C cleavage reaction was subject to an inverse kinetic solvent isotope effect analogous to that observed in the lyase activity of the human P450 CYP17A1, suggesting the involvement of a species earlier than Compound I in the catalytic cycle. Co-crystallization of F182L-CYP199A4 with this α-hydroxy ketone showed that the substrate bound in the active site with a preference for the (S)-enantiomer in a position which could mimic the topology of the lyase reaction in CYP17A1. Molecular dynamics simulations with an oxy-ferrous model of CYP199A4 revealed a displacement of the substrate to allow for oxygen binding and the formation of the lyase transition state proposed for CYP17A1. This demonstration that a correctly positioned α-hydroxy ketone substrate can realize lyase activity with an unusual inverse solvent isotope effect in an engineered microbial system opens the door for further detailed biophysical and structural characterization of CYP catalytic intermediates.
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Liases , Humanos , Domínio Catalítico , Catálise , Simulação de Dinâmica MolecularRESUMO
KRas4b is a membrane-bound regulatory protein belonging to the family of small GTPases that function as a molecular switch, facilitating signal transduction from activated membrane receptors to intracellular pathways controlling cell growth and proliferation. Oncogenic mutations locking KRas4b in the active GTP state are responsible for nearly 85% of all Ras-driven cancers. Understanding the membrane-bound state of KRas4b is crucial for designing new therapeutic approaches targeting oncogenic KRas-driven signaling pathways. Extensive research demonstrates the significant involvement of the membrane bilayer in Ras-effector interactions, with anionic lipids playing a critical role in determining protein conformations The preferred topology of KRas4b for interacting with signaling partners has been a long-time question. Computational studies suggest a membrane-proximal conformation, while other biophysical methods like neutron reflectivity propose a membrane-distal conformation. To address these gaps, we employed FRET measurements to investigate the conformation of KRas4b. Using fully post-translationally modified KRas4b, we designed a Nanodisc based FRET assay to study KRas4b-membrane interactions. We suggest an extended conformation of KRas4b relative to the membrane surface. Measurement of FRET donor - acceptor distances reveal that a negatively charged membrane surface weakly favors closer association with the membrane surface. Our findings provide insights into the role of anionic lipids in determining the dynamic conformations of KRas4b and shed light on the predominant conformation of its topology on lipid headgroups.
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Bioensaio , Lipídeos , Biofísica , Ciclo Celular , Proliferação de CélulasRESUMO
A 32-year-old nulliparous woman with premature ovarian insufficiency POI and autoimmune polyglandular syndrome type 2 (APS-2), presented to our fertility center with a 2.5-year history of amenorrhoea. Controlled ovarian hyperstimulation (COH), with high dose gonadotropins, failed to promote antral follicle growth. The patient was given a short, 4-week course of 2 mg dexamethasone prior to a repeat COH cycle, which resulted in the retrieval of good oocyte numbers and eventual live birth from a thawed embryo transfer.
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Síndrome de Hiperestimulação Ovariana , Poliendocrinopatias Autoimunes , Insuficiência Ovariana Primária , Gravidez , Feminino , Humanos , Glucocorticoides/farmacologia , Poliendocrinopatias Autoimunes/complicações , Poliendocrinopatias Autoimunes/tratamento farmacológico , Nascido Vivo , Insuficiência Ovariana Primária/tratamento farmacológicoRESUMO
We developed an efficient and sensitive probe for drug-drug interactions mediated by human CYP3A4 by using midazolam (MDZ) as a probe substrate. Using global analysis of four parameters over several experimental data sets, we demonstrate that the first MDZ molecule (MDZ1) binds with high affinity at the productive site near the heme iron and gives only hydroxylation at the 1 position (1OH). The second midazolam molecule (MDZ2) binds at an allosteric site at the membrane surface and perturbs the position and mobility of MDZ1 such that the minor hydroxylation product at the 4 position (4OH) is formed in a 1:2 ratio (35%). No increase in catalytic rate is observed after the second MDZ binding. Hence, the site of the 1OH:4OH metabolism ratio is a sensitive probe for drugs, such as progesterone, that bind with high affinity to the allosteric site and serve as effectors. We observe similar changes in the MDZ 1OH:4OH ratio in the presence of progesterone (PGS), suggesting a direct communication between the active and allosteric sites. Mutations introduced into the F-F' loop indicate that residues F213 and D214 are directly involved in allosteric interactions leading to MDZ homotropic cooperativity, and these same residues, together with L211, are involved in heterotropic allosteric interactions in which PGS is the effector and MDZ the substrate. Molecular dynamics simulations provide a mechanistic picture of the origin of this cooperativity. These results show that the midazolam can be used as a sensitive probe for drug-drug interactions in human P450 CYP3A4.
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Citocromo P-450 CYP3A/metabolismo , Midazolam/química , Midazolam/farmacologia , Regulação Alostérica/fisiologia , Sítio Alostérico , Citocromo P-450 CYP3A/efeitos dos fármacos , Citocromo P-450 CYP3A/fisiologia , Interações Medicamentosas/fisiologia , Humanos , Hidroxilação/efeitos dos fármacos , Cinética , Simulação de Dinâmica MolecularRESUMO
Atom probe tomography (APT)-based isotopic analyses are becoming increasingly attractive for analysis applications requiring small volumes of material and sub-micrometer length scales, such as isotope geochemistry, nuclear safety, and materials science. However, there is an open question within the atom probe community as to the reliability of atom probe isotopic and elemental analyses. Using our proposed analysis guidelines, in conjunction with an empirical calibration curve and a machine learning-based adaptive peak fitting algorithm, we demonstrate accurate and repeatable uranium isotopic analyses, via atom probe mass spectrometry, on U3O8 isotopic reference materials. By using isotopic reference materials, each measured isotopic abundance value could be directly compared to a known certified reference value to permit a quantitative statement of accuracy. The isotopic abundance measurements for 235U and 238U in each individual APT sample were consistently within ±1.5% relative to the known reference values. The accuracy and repeatability are approaching values consistent with measurements limited primarily by Poisson counting statistics, i.e., the number of uranium atoms recorded.
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We describe the construction, expression and purification of three new membrane scaffold proteins (MSP) for use in assembling Nanodiscs. These new MSPs have a variety of luminescent properties for use in combination with several analytical methods. "Dark" MSP has no tryptophan residues, "Ultra-Dark" replaces both tryptophan and tyrosine with non-fluorescent side chains, and "Ultra-Bright" adds additional tryptophans to the parent membrane scaffold protein to provide a dramatic increase in native tryptophan fluorescence. All MSPs were used to successfully assemble Nanodiscs nominally 10 nm in diameter, and the resultant bilayer structure was characterized. An example of the usefulness of these new scaffold proteins is provided.
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Peptídeos Catiônicos Antimicrobianos/química , Corantes Fluorescentes/química , Proteínas de Membrana/química , Triptofano/química , Tirosina/química , Sequência de Aminoácidos , Bicamadas Lipídicas/química , Ligação Proteica , Multimerização Proteica , Espectrometria de FluorescênciaRESUMO
KRAS4b is a small GTPase involved in cellular signaling through receptor tyrosine kinases. The activation of KRAS4b occurs only after recruitment of the regulatory proteins to the plasma membrane, thus making the role of the phospholipid bilayer an integral part of the signaling mechanism. Phospholipids, primarily with anionic headgroups, interact with both the membrane-anchoring hypervariable (HVR) region and the G-domain (catalytic domain) and influence the orientation of KRAS4b on the membrane surface, potentially playing a key role in the regulation of activation. Although there has been significant research focused on the role of the anionic phosphatidylserine, less effort has been spent on the role of the important signaling lipid phosphatidylinositol 4,5-bisphosphate (PIP2). Using instrumentation to measure the fluorescence anisotropy decay of site specifically labeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) Nanodiscs over a wide frequency range, we quantitate the binding of KRAS4b to Nanodiscs containing either 30% phosphatidylserine (PS) or 10% l-α-phosphatidylinositol 4,5-bisphosphate by measuring the rotational correlation time of the Nanodisc-KRAS4b complex. We find that KRAS4b binds significantly tighter to Nanodiscs containing PIP2 but that at any level of binding saturation of KRAS4b, both 30% PS and 10% PIP2 containing Nanodiscs display similar rotational correlation times. This shows that the overall hydrodynamic radii of the KRAS4b-Nanodisc complexes are similar regardless of the incorporated anionic lipid. Atomic force microscopy is used to visualize KRAS4b when bound to individual Nanodiscs. Clean images are observed with the PIP2-doped Nanodiscs, but significantly blurred images are obtained when the anionic lipid is PS. This suggests that KRAS4b is not only more tightly bound overall with PIP2 as the anionic lipid but also less mobile on the bilayer surface. Microsecond molecular dynamics simulations of KRAS4b on PS- and PIP2-containing membranes show that the dynamics of the G-domain at the bilayer surface are significantly altered in the presence of PIP2, due to the formation of long-lived salt bridges with basic residues on the G-domain. The orientation and dynamics of KRAS4b on the membrane are critical to understanding the mechanisms of oncoprotein signaling, and our results with the GDP-bound form show subtle differences from that published for GTP-KRAS4b.
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Fosfatidilinositol 4,5-Difosfato/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Domínio Catalítico , Membrana Celular/metabolismo , Humanos , Simulação de Dinâmica Molecular , Fosfatidilserinas/metabolismo , Ligação Proteica , Conformação Proteica , Proteínas Proto-Oncogênicas p21(ras)/químicaRESUMO
OBJECTIVE: To determine whether routine blood glucose assessment of patients admitted to hospital from emergency departments (EDs) results in higher rates of new diagnoses of diabetes and documentation of follow-up plans. DESIGN, SETTING: Cluster randomised trial in 18 New South Wales public district and tertiary hospitals, 31 May 2011 - 31 December 2012; outcomes follow-up to 31 March 2016. PARTICIPANTS: Patients aged 18 years or more admitted to hospital from EDs. INTERVENTION: Routine blood glucose assessment at control and intervention hospitals; automatic requests for glycated haemoglobin (HbA1c ) assessment and notification of diabetes services about patients at intervention hospitals with blood glucose levels of 14 mmol/L or more. MAIN OUTCOME MEASURE: New diagnoses of diabetes and documented follow-up plans for patients with admission blood glucose levels of 14 mmol/L or more. RESULTS: Blood glucose was measured in 133 837 patients admitted to hospital from an ED. The numbers of new diabetes diagnoses with documented follow-up plans for patients with blood glucose levels of 14 mmol/L or more were similar in intervention (83/506 patients, 16%) and control hospitals (73/278, 26%; adjusted odds ratio [aOR], 0.83; 95% CI 0.42-1.7; P = 0.61), as were new diabetes diagnoses with or without plans (intervention, 157/506, 31%; control, 86/278, 31%; aOR, 1.51; 95% CI, 0.83-2.80; P = 0.18). 30-day re-admission (31% v 22%; aOR, 1.34; 95% CI, 0.86-2.09; P = 0.21) and post-hospital mortality rates (24% v 22%; aOR, 1.07; 95% CI, 0.74-1.55; P = 0.72) were also similar for patients in intervention and control hospitals. CONCLUSION: Glucose and HbA1c screening of patients admitted to hospital from EDs does not alone increase detection of previously unidentified diabetes. Adequate resourcing and effective management pathways for patients with newly detected hyperglycaemia and diabetes are needed. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12611001007921.
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Glicemia/análise , Diabetes Mellitus/diagnóstico , Testes Diagnósticos de Rotina/estatística & dados numéricos , Serviços Médicos de Emergência/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Diabetes Mellitus/epidemiologia , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Hiperglicemia/diagnóstico , Hiperglicemia/epidemiologia , Masculino , Pessoa de Meia-Idade , New South WalesRESUMO
Applying high-resolution electron backscatter diffraction (HR-EBSD) to materials without regions that are amenable to the acquisition of backgrounds for static flat fielding (background subtraction) can cause analysis problems. To address this difficulty, the efficacy of electron beam induced deposition (EBID) of material as a source for an amorphous background signal is assessed and found to be practical. Using EBID material for EBSD backgrounds allows single crystal and large-grained samples to be analyzed using HR-EBSD for strain and small angle rotation measurement.
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Background: Hospital-based clinical addiction medicine training can improve knowledge of clinical care for substance-using populations. However, application of structured, self-assessment tools to evaluate differences in knowledge gained by learners who participate in such training has not yet been addressed. Methods: Participants (n = 142) of an elective with the hospital-based Addiction Medicine Consult Team (AMCT) in Vancouver, Canada, responded to an online self-evaluation survey before and immediately after the structured elective. Areas covered included substance use screening, history taking, signs and symptoms examination, withdrawal treatment, relapse prevention, nicotine use disorders, opioid use disorders, safe prescribing, and the biology of substance use disorders. A purposefully selected sample of 18 trainees were invited to participate in qualitative interviews that elicited feedback on the rotation. Results: Of 168 invited trainees, 142 (84.5%) completed both pre- and post-rotation self-assessments between May 2015 and May 2017. Follow-up participants included medical students, residents, addiction medicine fellows, and family physicians in practice. Self-assessed knowledge of addiction medicine increased significantly post-rotation (mean difference in scores = 11.87 out of the maximum possible 63 points, standard deviation = 17.00; P < .0001). Medical students were found to have the most significant improvement in addiction knowledge (estimated mean difference = 4.43, 95% confidence interval = 0.76, 8.09; P = .018). Illustrative quotes describe the dynamics involved in the learning process among trainees. Conclusions: Completion of a hospital-based clinical elective was associated with improved knowledge of addiction medicine. Medical students appear to benefit more from the addiction elective with a hospital-based AMCT than other types of learners.
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Medicina do Vício/educação , Currículo , Educação Médica/métodos , Educação em Enfermagem/métodos , Adulto , Colúmbia Britânica , Bolsas de Estudo , Hospitais , Humanos , Internato e Residência , Médicos de Família/educação , Pesquisa Qualitativa , Encaminhamento e Consulta , Serviço Social/educação , Estudantes de MedicinaRESUMO
BACKGROUND: Gestational diabetes mellitus (GDM) causes adverse pregnancy outcomes that can be averted by treatment from 24-28 weeks' gestation. Assessing and treating women for overt diabetes in pregnancy (ODIP) at the first antenatal clinic booking is now recommended in international guidelines. As a consequence, women with milder hyperglycaemia are being diagnosed and treated for early GDM, but randomised controlled trial (RCTs) assessing the benefits and harms of such treatment have not been undertaken. The Treatment Of Booking Gestational diabetes Mellitus (TOBOGM) study is a multi-centre RCT examining whether diagnosing and treating GDM diagnosed at booking improves pregnancy outcomes. Methods and analysis: 4000 adult pregnant women (< 20 weeks' gestation) at risk of ODIP will be recruited from 12 hospital antenatal booking clinics and referred for an oral glucose tolerance test (OGTT). 800 women with hyperglycaemia (ie, booking GDM) according to the 2014 Australasian Diabetes-in-Pregnancy Society criteria for pregnant women at 24-28 weeks' gestation will be randomised to immediate treatment for GDM (intervention) or to no treatment (control), pending the results of a second OGTT at 24-28 weeks' gestation. Antenatal and GDM care will otherwise follow local guidelines. Randomisation will be stratified by site and OGTT glycaemic risk strata. The primary pregnancy outcome is a composite of respiratory distress, phototherapy, birth trauma, birth before 37 weeks' gestation, stillbirth or death, shoulder dystocia, and birthweight ≥ 4.5 kg. The primary neonatal outcome is neonatal lean body mass. The primary maternal outcome is pre-eclampsia. Ethics approval: South Western Sydney Local Health District Research and Ethics Office (reference, 15/LPOOL/551). Dissemination of results: Peer-reviewed publications, scientific meetings, collaboration with research groups undertaking comparable studies, discussions with guideline groups and policy makers. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12616000924459.
Assuntos
Diabetes Gestacional/terapia , Idade Gestacional , Hiperglicemia/terapia , Complicações na Gravidez/terapia , Adulto , Austrália , Diabetes Gestacional/diagnóstico , Feminino , Teste de Tolerância a Glucose , Humanos , Hiperglicemia/diagnóstico , Guias de Prática Clínica como Assunto , Gravidez , Complicações na Gravidez/diagnóstico , Resultado da Gravidez , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Importance: Although severe alcohol withdrawal syndrome (SAWS) is associated with substantial morbidity and mortality, most at-risk patients will not develop this syndrome. Predicting its occurrence is important because the mortality rate is high when untreated. Objective: To assess the accuracy and predictive value of symptoms and signs for identifying hospitalized patients at risk of SAWS, defined as delirium tremens, withdrawal seizure, or clinically diagnosed severe withdrawal. Data Sources: MEDLINE and EMBASE (1946-January 2018) were searched for articles investigating symptoms and signs predictive of SAWS in adults. Reference lists of retrieved articles were also searched. Study Selection: Original studies that were included compared symptoms, signs, and risk assessment tools among patients who developed SAWS and patients who did not. Data Extraction and Synthesis: Data were extracted and used to calculate likelihood ratios (LRs), sensitivity, and specificity. A meta-analysis was performed to calculate summary LR. Results: Of 530 identified studies, 14 high-quality studies that included 71â¯295 patients and 1355 relevant cases of SAWS (1051 cases), seizure (53 cases), or delirium tremens (251 cases) were analyzed. A history of delirium tremens (LR, 2.9 [95% CI 1.7-5.2]) and baseline systolic blood pressure 140 mm Hg or higher (LR, 1.7 [95% CI, 1.3-2.3) were associated with an increased likelihood of SAWS. No single symptom or sign was associated with exclusion of SAWS. Six high-quality studies evaluated combinations of clinical findings and were useful for identifying patients in acute care facilities at high risk of developing SAWS. Of these combinations, the Prediction of Alcohol Withdrawal Severity Scale (PAWSS) was most useful, with an LR of 174 (95% CI, 43-696; specificity, 0.93) when patients had 4 or more individual findings and an LR of 0.07 (95% CI, 0.02-0.26; sensitivity, 0.99) when there were 3 or fewer findings. Conclusions and Relevance: Assessment tools that use a combination of symptoms and signs are useful for identifying patients at risk of developing severe alcohol withdrawal syndrome. Most studies of these tools were not fully validated, limiting their generalizability.
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Alcoolismo/complicações , Etanol/efeitos adversos , Medição de Risco/métodos , Síndrome de Abstinência a Substâncias/etiologia , Feminino , Humanos , Incidência , Funções Verossimilhança , Masculino , Fatores de Risco , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Síndrome de Abstinência a Substâncias/epidemiologiaRESUMO
A critical step in the activation of integrin receptors is the binding of talin to the cytoplasmic domain of the ß subunits. This interaction leads to separation of the integrin α and ß transmembrane domains and significant conformational changes in the extracellular domains, resulting in a dramatic increase in integrin's affinity for ligands. It has long been shown that the membrane bilayer also plays a critical role in the talin-integrin interaction. Anionic lipids are required for proper interaction, yet the specificity for specific anionic headgroups is not clear. In this report, we document talin-membrane interactions with bilayers of controlled composition using Nanodiscs and a FRET based binding and structural assay. We confirm that recruitment of the talin head domain to the membrane surface is governed by charge in the absence of other adapter proteins. In addition, measurement of the donor-acceptor distance is consistent with the hypothesis that anionic lipids promote a conformational change in the talin head domain allowing interaction of the F3 domain with the phospholipid bilayer. The magnitude of the F3 domain movement is altered by the identity of the phospholipid headgroup with phosphatidylinositides promoting the largest change. Our results suggest that phoshpatidylinositol-4,5-bisphosphate plays key a role in converting talin head domain to a conformation optimized for interactions with the bilayer and subsequently integrin cytoplasmic tails.
Assuntos
Bicamadas Lipídicas/química , Lipídeos de Membrana/química , Proteínas de Membrana/química , Talina/química , Substituição de Aminoácidos , Ânions/química , Transferência Ressonante de Energia de Fluorescência , Proteínas de Membrana/genética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Mutação , Nanoestruturas , Fosfatidilinositol 4,5-Difosfato/química , Conformação Proteica , Domínios Proteicos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Rodaminas , Eletricidade Estática , Talina/genéticaRESUMO
KRas4b is a small G-protein whose constitutively active oncogenic mutants are present in 90% of pancreatic cancers. Using fully post-translationally modified KRAS4b, we investigated the role of lipid identity in the recruitment of KRas4b to a membrane surface of defined composition. Application of a newly developed single frequency fluorescence anisotropy decay experiment to this system revealed that KRas4b has a significant binding preference for Nanodisc bilayers containing PIP2. We conducted molecular dynamics simulations to look for an origin of this specificity. In the case of membranes containing PIP2 the protein formed long-lived salt bridges with PIP2 head groups but not the monovalent DMPS, explaining the experimentally observed lipid specificity. Additionally, we report that PIP2 forms key contacts with Helix-4 on the catalytic domain of KRas4b that orient the protein in a manner expected to facilitate association with upstream and downstream signaling partners.
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Ânions/química , Bicamadas Lipídicas/química , Simulação de Acoplamento Molecular , Fosfatidilinositol 4,5-Difosfato/química , Proteínas Proto-Oncogênicas p21(ras)/química , Proteínas Proto-Oncogênicas p21(ras)/ultraestrutura , Sítios de Ligação , Modelos Químicos , Ligação Proteica , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
BACKGROUND: Hyperglycemia is associated with increased morbidity and mortality in patients with an acute myocardial infarction (AMI). We evaluated whether complications after AMI are associated with absolute or relative glycemia. METHODS: A total of 192 patients with AMI were randomized to intensive or conventional insulin therapy. Absolute glycemia was defined as mean blood glucose level (BGL) during the first 24 h following randomization. Relative glycemia was defined by the stress hyperglycaemia ratio (SHR), calculated as mean BGL divided by average glucose concentration over the prior 3 months estimated from glycosylated haemoglobin. The primary endpoint was a "complicated AMI", defined as an AMI complicated by death, congestive cardiac failure, arrhythmia, cardiac arrest, reinfarction, cardiogenic shock, inotrope use or emergency revascularization. RESULTS: There was not a significant association between mean BGL and complicated AMI (odds ratio (OR) 1.05 per mmol/L glucose increment, 95% confidence intervals (CI) 0.93-1.19). In contrast, SHR was positively associated with a complicated myocardial infarction (OR 1.22 per 0.1 SHR increment, 95% CI 1.06-1.42), and individual complications of death (OR 1.55, 95% CI 1.14-2.11), congestive cardiac failure (OR 1.27, 95% CI 1.05-1.54), arrhythmia (OR 1.31, 95% CI 1.12-1.54) and cardiogenic shock (OR 1.42, 95% CI 1.03-1.97). The relationship between SHR and a complicated AMI was independent of diabetic status, intensive insulin therapy, sex and hypoglycemia. CONCLUSIONS: Relative, but not absolute, glycemia during insulin treatment is independently associated with complications after an AMI. Future studies should investigate whether basing therapeutic glycaemic targets on relative glycemia improves patient outcomes.
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Glicemia/efeitos dos fármacos , Hiperglicemia/tratamento farmacológico , Hipoglicemiantes/administração & dosagem , Insulina/administração & dosagem , Infarto do Miocárdio/complicações , Idoso , Biomarcadores/sangue , Glicemia/metabolismo , Distribuição de Qui-Quadrado , Progressão da Doença , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Hiperglicemia/sangue , Hiperglicemia/complicações , Hiperglicemia/mortalidade , Hipoglicemiantes/efeitos adversos , Insulina/efeitos adversos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/sangue , Infarto do Miocárdio/mortalidade , Infarto do Miocárdio/terapia , Revascularização Miocárdica , Razão de Chances , Ensaios Clínicos Controlados Aleatórios como Assunto , Recidiva , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoRESUMO
KEY MESSAGE: QTL for tan spot resistance were mapped on wheat chromosomes 1A and 2A. Lines were developed with resistance alleles at these loci and at the tsn1 locus on chromosome 5B. These lines expressed significantly higher resistance than the parent with tsn1 only. Tan spot (syn. yellow spot and yellow leaf spot) caused by Pyrenophora tritici-repentis is an important foliar disease of wheat in Australia. Few resistance genes have been mapped in Australian germplasm and only one, known as tsn1 located on chromosome 5B, is known in Australian breeding programs. This gene confers insensitivity to the fungal effector ToxA. The main aim of this study was to map novel resistance loci in two populations: Calingiri/Wyalkatchem, which is fixed for the ToxA-insensitivity allele tsn1, and IGW2574/Annuello, which is fixed for the ToxA-sensitivity allele Tsn1. A second aim was to combine new loci with tsn1 to develop lines with improved resistance. Tan spot severity was evaluated at various growth stages and in multiple environments. Symptom severity traits exhibited quantitative variation. The most significant quantitative trait loci (QTL) were detected on chromosomes 2A and 1A. The QTL on 2A explained up to 29.2% of the genotypic variation in the Calingiri/Wyalkatchem population with the resistance allele contributed by Wyalkatchem. The QTL on 1A explained up to 28.1% of the genotypic variation in the IGW2574/Annuello population with the resistance allele contributed by Annuello. The resistance alleles at both QTL were successfully combined with tsn1 to develop lines that express significantly better resistance at both seedling and adult plant stages than Calingiri which has tsn1 only.
Assuntos
Resistência à Doença/genética , Doenças das Plantas/genética , Locos de Características Quantitativas , Triticum/genética , Alelos , Ascomicetos , Austrália , Mapeamento Cromossômico , Cromossomos de Plantas , Modelos Lineares , Modelos Genéticos , Fenótipo , Doenças das Plantas/microbiologia , Triticum/microbiologiaRESUMO
Pyrenophora teres f. teres and P. teres f. maculata cause net form and spot form, respectively, of net blotch on barley (Hordeum vulgare). The two forms reproduce sexually, producing hybrids with genetic and pathogenic variability. Phenotypic identification of hybrids is challenging because lesions induced by hybrids on host plants resemble lesions induced by either P. teres f. teres or P. teres f. maculata. In this study, 12 sequence-specific polymerase chain reaction markers were developed based on expressed regions spread across the genome. The primers were validated using 210 P. teres isolates, 2 putative field hybrids (WAC10721 and SNB172), 50 laboratory-produced hybrids, and 7 isolates collected from barley grass (H. leporinum). The sequence-specific markers confirmed isolate WAC10721 as a hybrid. Only four P. teres f. teres markers amplified on DNA of barley grass isolates. Amplified fragment length polymorphism markers suggested that P. teres barley grass isolates are genetically different from P. teres barley isolates and that the second putative hybrid (SNB172) is a barley grass isolate. We developed a suite of markers which clearly distinguish the two forms of P. teres and enable unambiguous identification of hybrids.