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1.
Nature ; 584(7819): E4, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32690939

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

2.
Nature ; 566(7745): 518-522, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30742073

RESUMO

The major breakthroughs in understanding of topological materials over the past decade were all triggered by the discovery of the Z2-type topological insulator-a type of material that is insulating in its interior but allows electron flow on its surface. In three dimensions, a topological insulator is classified as either 'strong' or 'weak'1,2, and experimental confirmations of the strong topological insulator rapidly followed theoretical predictions3-5. By contrast, the weak topological insulator (WTI) has so far eluded experimental verification, because the topological surface states emerge only on particular side surfaces, which are typically undetectable in real three-dimensional crystals6-10. Here we provide experimental evidence for the WTI state in a bismuth iodide, ß-Bi4I4. Notably, the crystal has naturally cleavable top and side planes-stacked via van der Waals forces-which have long been desirable for the experimental realization of the WTI state11,12. As a definitive signature of this state, we find a quasi-one-dimensional Dirac topological surface state at the side surface (the (100) plane), while the top surface (the (001) plane) is topologically dark with an absence of topological surface states. We also find that a crystal transition from the ß-phase to the α-phase drives a topological phase transition from a nontrivial WTI to a normal insulator at roughly room temperature. The weak topological phase-viewed as quantum spin Hall insulators stacked three-dimensionally13,14-will lay a foundation for technology that benefits from highly directional, dense spin currents that are protected against backscattering.

3.
Phys Rev Lett ; 131(4): 046401, 2023 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-37566843

RESUMO

The recent observation of correlated phases in transition metal dichalcogenide moiré systems at integer and fractional filling promises new insight into metal-insulator transitions and the unusual states of matter that can emerge near such transitions. Here, we combine real- and momentum-space mapping techniques to study moiré superlattice effects in 57.4° twisted WSe_{2} (tWSe_{2}). Our data reveal a split-off flat band that derives from the monolayer Γ states. Using advanced data analysis, we directly quantify the moiré potential from our data. We further demonstrate that the global valence band maximum in tWSe_{2} is close in energy to this flat band but derives from the monolayer K states which show weaker superlattice effects. These results constrain theoretical models and open the perspective that Γ-valley flat bands might be involved in the correlated physics of twisted WSe_{2}.

4.
Phys Rev Lett ; 131(23): 236502, 2023 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-38134803

RESUMO

We study the temperature evolution of quasiparticles in the correlated metal Sr_{2}RuO_{4}. Our angle resolved photoemission data show that quasiparticles persist up to temperatures above 200 K, far beyond the Fermi liquid regime. Extracting the quasiparticle self-energy, we demonstrate that the quasiparticle residue Z increases with increasing temperature. Quasiparticles eventually disappear on approaching the bad metal state of Sr_{2}RuO_{4} not by losing weight but via excessive broadening from super-Planckian scattering. We further show that the Fermi surface of Sr_{2}RuO_{4}-defined as the loci where the spectral function peaks-deflates with increasing temperature. These findings are in semiquantitative agreement with dynamical mean field theory calculations.

5.
J Sports Sci ; 41(24): 2236-2250, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38446499

RESUMO

Low back pain (LBP) is the most common injury in golfers of all abilities. The primary aim of this review was to improve understanding of human golf swing biomechanics associated with LBP. A systematic review using the PRISMA guidelines was performed. Nine studies satisfying inclusion criteria and dually reporting golf swing biomechanics and LBP were identified. Human golf swing biomechanics potentially associated with LBP include: reduced lumbar flexion velocity; reduced transition phase length; reduced lumbar torsional load; earlier onset of erector spinae contraction; increased lumbar lateral flexion velocity; reduced or greater erector spinae activity; and earlier onset of external oblique contraction. These potential associations were undermined by a very limited and conflicting quality of evidence, study designs which introduced a severe potential for bias and a lack of prospective study design. There is no conclusive evidence to support the commonly held belief that LBP is associated with "poor" golf swing technique. The potential associations identified should be further investigated by prospective studies of robust design, recruiting participants of both sexes and dexterities. Once firm associations have been identified, further research is required to establish how this knowledge can be best integrated into injury prevention and rehabilitation.


LBP has the highest incidence of any injury in elite, sub-elite and recreational golfers, causing a significant burden of injury worldwide.There is very limited and conflicting evidence that some human biomechanical factors in the golf swing may be associated with LBP.Prospective studies investigating the full movement pattern are required in order to improve understanding of the potential relationship between the biomechanics of the golf swing and LBP.


Assuntos
Golfe , Dor Lombar , Masculino , Feminino , Humanos , Dor Lombar/etiologia , Dor Lombar/prevenção & controle , Golfe/lesões , Estudos Prospectivos , Região Lombossacral , Fenômenos Biomecânicos
6.
Respir Res ; 22(1): 157, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34020644

RESUMO

BACKGROUND: The long-term consequences of COVID-19 remain unclear. There is concern a proportion of patients will progress to develop pulmonary fibrosis. We aimed to assess the temporal change in CXR infiltrates in a cohort of patients following hospitalisation for COVID-19. METHODS: We conducted a single-centre prospective cohort study of patients admitted to University Hospital Southampton with confirmed SARS-CoV2 infection between 20th March and 3rd June 2020. Patients were approached for standard-of-care follow-up 12-weeks after hospitalisation. Inpatient and follow-up CXRs were scored by the assessing clinician for extent of pulmonary infiltrates; 0-4 per lung (Nil = 0, < 25% = 1, 25-50% = 2, 51-75% = 3, > 75% = 4). RESULTS: 101 patients with paired CXRs were included. Demographics: 53% male with a median (IQR) age 53.0 (45-63) years and length of stay 9 (5-17.5) days. The median CXR follow-up interval was 82 (77-86) days with median baseline and follow-up CXR scores of 4.0 (3-5) and 0.0 (0-1) respectively. 32% of patients had persistent CXR abnormality at 12-weeks. In multivariate analysis length of stay (LOS), smoking-status and obesity were identified as independent risk factors for persistent CXR abnormality. Serum LDH was significantly higher at baseline and at follow-up in patients with CXR abnormalities compared to those with resolution. A 5-point composite risk score (1-point each; LOS ≥ 15 days, Level 2/3 admission, LDH > 750 U/L, obesity and smoking-status) strongly predicted risk of persistent radiograph abnormality (0.81). CONCLUSION: Persistent CXR abnormality 12-weeks post COVID-19 was common in this cohort. LOS, obesity, increased serum LDH, and smoking-status were risk factors for radiograph abnormality. These findings require further prospective validation.


Assuntos
COVID-19/complicações , COVID-19/diagnóstico por imagem , Tórax/diagnóstico por imagem , Idoso , Estudos de Coortes , Feminino , Seguimentos , Hospitalização , Humanos , L-Lactato Desidrogenase/sangue , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Obesidade , Reação em Cadeia da Polimerase , Estudos Prospectivos , Radiografia Torácica , Fatores de Risco , Fumar , Resultado do Tratamento
7.
BMC Fam Pract ; 21(1): 244, 2020 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-33248452

RESUMO

BACKGROUND: The expansion of community pharmacy services is one solution to relieve pressure on general practice in the United Kingdom (UK). There is a paucity of research of general practitioners' (GPs') perspectives of quality of care in the community pharmacy sector. The purpose of this study was to explore GPs': Conceptualisation of quality for community pharmacy services, including the management of acute (low acuity) conditions and defining indispensable aspects of the patient experience ('always events') Opinions regarding whether and how to measure quality in the community pharmacy sector METHOD: Semi-structured interviews were conducted with GPs in the UK. GPs were recruited using the snowballing technique and professional networks. Interviews were audio-recorded, transcribed and analysed using an interpretive approach. RESULTS: Interviews were completed with 20 GPs from Scotland (n = 8) and England (n = 12). Multidimensional and inter-related concepts of quality were identified; most dimensions related to patient benefit, as well as impact on GP workload or other health service provision. Interviewees cautioned that "what counts can't always be measured". GPs' expectations of quality often mirrored those of their own sector, but were ambivalent about the adoption of a quality outcome framework-type approach. Pharmacist involvement was expected to ensure quality in the management of 'acute consultations', however, GPs lacked awareness of community pharmacy personnel type, roles and training. Interviewees' perceptions of quality varied by pharmacy type; independent pharmacies were sometimes associated with higher quality service delivery than larger chain organisations. CONCLUSIONS: Quality frameworks for community pharmacy services could be partly informed by GP experience and expectations, but need to be contextual to reflect differences between both settings. The importance of person-centred care, consistency and continuity was emphasised together with the need for competent personnel and privacy of interactions.


Assuntos
Serviços Comunitários de Farmácia , Clínicos Gerais , Atitude do Pessoal de Saúde , Formação de Conceito , Humanos , Farmacêuticos , Pesquisa Qualitativa
8.
Heredity (Edinb) ; 122(1): 53-68, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29720718

RESUMO

Understanding how dispersal and gene flow link geographically separated the populations over evolutionary history is challenging, particularly in migratory marine species. In southern right whales (SRWs, Eubalaena australis), patterns of genetic diversity are likely influenced by the glacial climate cycle and recent history of whaling. Here we use a dataset of mitochondrial DNA (mtDNA) sequences (n = 1327) and nuclear markers (17 microsatellite loci, n = 222) from major wintering grounds to investigate circumpolar population structure, historical demography and effective population size. Analyses of nuclear genetic variation identify two population clusters that correspond to the South Atlantic and Indo-Pacific ocean basins that have similar effective breeder estimates. In contrast, all wintering grounds show significant differentiation for mtDNA, but no sex-biased dispersal was detected using the microsatellite genotypes. An approximate Bayesian computation (ABC) approach with microsatellite markers compared the scenarios with gene flow through time, or isolation and secondary contact between ocean basins, while modelling declines in abundance linked to whaling. Secondary-contact scenarios yield the highest posterior probabilities, implying that populations in different ocean basins were largely isolated and came into secondary contact within the last 25,000 years, but the role of whaling in changes in genetic diversity and gene flow over recent generations could not be resolved. We hypothesise that these findings are driven by factors that promote isolation, such as female philopatry, and factors that could promote dispersal, such as oceanographic changes. These findings highlight the application of ABC approaches to infer the connectivity in mobile species with complex population histories and, currently, low levels of differentiation.


Assuntos
Evolução Molecular , Variação Genética/genética , Genética Populacional , Baleias/genética , Animais , Clima , DNA Mitocondrial/genética , Fluxo Gênico/genética , Genótipo , Haplótipos/genética , Repetições de Microssatélites/genética , Oceano Pacífico , Filogenia , Densidade Demográfica , Baleias/fisiologia
9.
Phys Rev Lett ; 120(8): 086402, 2018 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-29543003

RESUMO

Experimental determinations of bulk band topology in the solid states have been so far restricted to only indirect investigation through the probing of surface states predicted by electronic structure calculations. We here present an alternative approach to determine the band topology by means of bulk-sensitive soft x-ray angle-resolved photoemission spectroscopy. We investigate the bulk electronic structures of the series materials, Ce monopnictides (CeP, CeAs, CeSb, and CeBi). By performing a paradigmatic study of the band structures as a function of their spin-orbit coupling, we draw the topological phase diagram and unambiguously reveal the topological phase transition from a trivial to a nontrivial regime in going from CeP to CeBi induced by the band inversion. The underlying mechanism of the phase transition is elucidated in terms of spin-orbit coupling in concert with their semimetallic band structures. Our comprehensive observations provide a new insight into the band topology hidden in the bulk states.

10.
Anaerobe ; 49: 53-57, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29269237

RESUMO

The comparatively high cost of laboratory detection methods for Clostridium difficile infection (CDI) coupled to a low prevalence rate has resulted in testing algorithms that use cheaper and relatively sensitive screening methods, followed by more specific confirmatory methods. The aim of this prospectively-conducted study from two centres in the UK, and one in the Republic of Ireland was to determine the efficacy of the EntericBio® realtime C. difficile Assay (EBCD) for the detection of toxigenic C. difficile in stool samples. The EBCD was compared to the in-use testing methods for Clostridium difficile (CD) detection in each centre. In the two UK centres, the EBCD was compared to the C.diff Quik Chek Complete® kit (Techlab), and discrepancies were tested further using The Xpert®C. difficile PCR assay (Cepheid) and PCR ribotyping after cultivation using the spore culture method, respectively. In the Irish centre, EBCD comparison was to an algorithm of C. DIFF CHEK™-60 test (Techlab) for screening followed by C. difficile Premier ™ Toxins A&B assay (Meridian Bioscience®) in the case of positive results; discrepancies were tested using the Xpert®C. difficile PCR assay. In a retrospective analysis of data, a total of 947 stool samples were tested, of which eight (0.8%) proved inhibitory to the EBCD assay. Of the 939 valid tests conducted, reported sensitivities of the EBCD were 94.7%, 100% and 97.9%, respectively; specificities were 99.6%, 100% and 100%, respectively; positive predictive values were 94.7%, 100% and 100%, respectively, and negative predictive values were 99.6%, 100% and 99.8%, respectively. The CD positivity rates in the current study ranged between 6.6% and 8.2%.


Assuntos
Toxinas Bacterianas/genética , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/microbiologia , Reação em Cadeia da Polimerase/métodos , Adolescente , Algoritmos , Toxinas Bacterianas/metabolismo , Criança , Pré-Escolar , Clostridioides difficile/classificação , Clostridioides difficile/genética , Fezes/microbiologia , Feminino , Humanos , Masculino , Estudos Prospectivos , Estudos Retrospectivos , Sensibilidade e Especificidade
11.
Ann Oncol ; 28(5): 1070-1077, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28453704

RESUMO

Background: HER2 (ERBB2) gene amplification and its corresponding overexpression are present in 15-30% of invasive breast cancers. While HER2-targeted agents are effective treatments, resistance remains a major cause of death. The American College of Surgeons Oncology Group Z1041 trial (NCT00513292) was designed to compare the pathologic complete response (pCR) rate of distinct regimens of neoadjuvant chemotherapy and trastuzumab, but ultimately identified no difference. Patients and methods: In supplement to tissues from 37 Z1041 cases, 11 similarly treated cases were obtained from a single institution study (NCT00353483). We have extracted genomic DNA from both pre-treatment tumor biopsies and blood of these 48 cases, and performed whole genome (WGS) and exome sequencing. Coincident with these efforts, we have generated RNA-seq profiles from 42 of the tumor biopsies. Among patients in this cohort, 24 (50%) achieved a pCR. Results: We have characterized the genomic landscape of HER2-positive breast cancer and investigated associations between genomic features and pCR. Cases assigned to the HER2-enriched subtype by RNA-seq analysis were more likely to achieve a pCR compared to the luminal, basal-like, or normal-like subtypes (19/27 versus 3/15; P = 0.0032). Mutational events led to the generation of putatively active neoantigens, but were overall not associated with pCR. ERBB2 and GRB7 were the genes most commonly observed in fusion events, and genomic copy number analysis of the ERBB2 locus indicated that cases with either no observable or low-level ERBB2 amplification were less likely to achieve a pCR (7/8 versus 17/40; P = 0.048). Moreover, among cases that achieved a pCR, tumors consistently expressed immune signatures that may contribute to therapeutic response. Conclusion: The identification of these features suggests that it may be possible to predict, at the time of diagnosis, those HER2-positive breast cancer patients who will not respond to treatment with chemotherapy and trastuzumab. ClinicalTrials.gov identifiers: NCT00513292, NCT00353483.


Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Trastuzumab/uso terapêutico , Idoso , Neoplasias da Mama/genética , Quimioterapia Adjuvante , Variações do Número de Cópias de DNA , Feminino , Estudos de Associação Genética , Genoma Humano , Mutação em Linhagem Germinativa , Humanos , Mutação INDEL , Pessoa de Meia-Idade , Terapia Neoadjuvante , Polimorfismo de Nucleotídeo Único , Receptor ErbB-2/metabolismo , Resultado do Tratamento
12.
Br J Surg ; 104(8): 1097-1106, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28425560

RESUMO

BACKGROUND: This study compared precision of depth judgements, technical performance and workload using two-dimensional (2D) and three-dimensional (3D) laparoscopic displays across different viewing distances. It also compared the accuracy of 3D displays with natural viewing, along with the relationship between stereoacuity and 3D laparoscopic performance. METHODS: A counterbalanced within-subjects design with random assignment to testing sequences was used. The system could display 2D or 3D images with the same set-up. A Howard-Dolman apparatus assessed precision of depth judgements, and three laparoscopic tasks (peg transfer, navigation in space and suturing) assessed performance (time to completion). Participants completed tasks in all combinations of two viewing modes (2D, 3D) and two viewing distances (1 m, 3 m). Other measures administered included the National Aeronautics and Space Administration Task Load Index (perceived workload) and the Randot® Stereotest (stereoacuity). RESULTS: Depth judgements were 6·2 times as precise at 1 m and 3·0 times as precise at 3 m using 3D versus 2D displays (P < 0·001). Participants performed all laparoscopic tasks faster in 3D at both 1 and 3 m (P < 0.001), with mean completion times up to 64 per cent shorter for 3D versus 2D displays. Workload was lower for 3D displays (up to 34 per cent) than for 2D displays at both viewing distances (P < 0·001). Greater viewing distance inhibited performance for two laparoscopic tasks, and increased perceived workload for all three (P < 0·001). Higher stereoacuity was associated with shorter completion times for the navigating in space task performed in 3D at 1 m (r = - 0·40, P = 0·001). CONCLUSION: 3D displays offer large improvements over 2D displays in precision of depth judgements, technical performance and perceived workload.


Assuntos
Competência Clínica/normas , Percepção de Profundidade/fisiologia , Laparoscopia/normas , Corpo Clínico Hospitalar/normas , Cirurgiões/normas , Adulto , Educação Médica/métodos , Humanos , Imageamento Tridimensional , Julgamento/fisiologia , Laparoscopia/educação , Corpo Clínico Hospitalar/educação , Corpo Clínico Hospitalar/psicologia , Percepção/fisiologia , Desempenho Psicomotor/fisiologia , Queensland , Treinamento por Simulação/métodos , Cirurgiões/educação , Cirurgiões/psicologia , Carga de Trabalho/estatística & dados numéricos
13.
Phys Rev Lett ; 118(9): 097002, 2017 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-28306267

RESUMO

We present angle-resolved photoemission spectroscopy measurements of the quasi-one-dimensional superconductor K_{2}Cr_{3}As_{3}. We find that the Fermi surface contains two Fermi surface sheets, with linearly dispersing bands not displaying any significant band renormalizations. The one-dimensional band dispersions display a suppression of spectral intensity approaching the Fermi level according to a linear power law, over an energy range of ∼200 meV. This is interpreted as a signature of Tomonoga-Luttinger liquid physics, which provides a new perspective on the possibly unconventional superconductivity in this family of compounds.

14.
Psychooncology ; 26(3): 301-308, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27943570

RESUMO

OBJECTIVE: To evaluate Telephone-Delivered Cognitive Behavioural Therapy (T-CBT) compared to CBT face to face treatment as usual (TAU-CBT), in cancer patients with high psychological needs, in terms of mental health and coping. METHOD: A prospective randomised equivalence trial with Patient Reported Outcome (PRO's), measured pre- and post-therapy including; Hospital Anxiety and Depression Scale (HADS), Mental Adjustment to Cancer Scale: Helpless/Hopeless subscale only (MAC H/H), Checklist of Cancer Concerns (CLCC) and the Cancer Coping Questionnaire (CCQ). A study-specific Service Evaluation Questionnaire (SEQ) was include. RESULTS: Assessment of change scores, in n = 118 randomised patients referred for psychological care, indicate significant improvements (P < 0.01 or greater) for both therapy groups pre- and post-therapy in HADS anxiety, depression and total scores and cancer concerns (CLCC). Overall, for the groups combined, there is a significant shift towards reduction of CCQ stress (P = 0.028) and worry (P = 0.003) post-therapy when compared to baseline levels. Median number of therapy sessions was four. For cancer coping (CCQ) and for Mental Adjustment to Cancer (MAC) there were significant change scores only for Positive Focus and Helpless/hopeless scores respectively, in the TAU-CBT group. Although equivalence was not observed, the data demonstrate that T-CBT was non-inferior to TAU-CBT. CONCLUSIONS: Delivery of CBT to patients with clinician identified high need can be offered according to patient choice without loss of mental health benefit. Both TAU-CBT and T-CBT are effective at reducing mental health problems on the specific outcome measures.


Assuntos
Ansiedade/terapia , Terapia Cognitivo-Comportamental/métodos , Depressão/terapia , Neoplasias/psicologia , Telemedicina/métodos , Telefone , Adaptação Psicológica , Idoso , Ansiedade/etiologia , Depressão/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/complicações , Neoplasias/terapia , Avaliação de Resultados em Cuidados de Saúde , Estudos Prospectivos , Inquéritos e Questionários
15.
Biol Lett ; 13(11)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29118240

RESUMO

The major histocompatibility complex (MHC) plays a key role in vertebrate immunity, and pathogen-mediated selection often favours certain allelic combinations. Assessing potential mates' MHC profiles may provide receivers with genetic benefits (identifying MHC-compatible mates and producing optimally diverse offspring) and/or material benefits (identifying optimally diverse mates capable of high parental investment). Oscine songbirds learn songs during early life, such that song repertoire content can reflect population of origin while song complexity can reflect early life condition. Thus birdsong may advertise the singer's genetic dissimilarity to others in the population (and, presumably, compatibility with potential mates), or individual genetic diversity (and thus condition-dependent material benefits). We tested whether song repertoire content and/or complexity signal MHC class IIß dissimilarity and/or diversity in male song sparrows (Melospiza melodia). Pairwise dissimilarity in repertoire content did not predict MHC dissimilarity between males, suggesting that locally rare songs do not signal rare MHC profiles. Thus, geographical variation in song may not facilitate MHC-mediated inbreeding or outbreeding. Larger repertoires were associated with intermediate MHC diversity, suggesting intermediate rather than maximal MHC diversity is optimal. This could reflect trade-offs between resisting infection and autoimmune disorders. Song complexity may advertise optimal MHC diversity, a trait affecting disease resistance and capacity for parental care.


Assuntos
Complexo Principal de Histocompatibilidade/genética , Pardais/fisiologia , Vocalização Animal , Animais , Variação Genética , Masculino , Pardais/genética
16.
J Vet Pharmacol Ther ; 40(6): 682-686, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28568310

RESUMO

This study was designed to investigate the pharmacokinetics of clindamycin, a lincosamide antibiotic, in Bennett's wallabies. The pharmacokinetic properties of a single intravenous (IV) dose of clindamycin were determined in six wallabies. A single 20-min IV infusion of 20 mg/kg of clindamycin was administered, followed by blood collection prior to, and up to 12 hr after clindamycin administration. Plasma clindamycin concentrations were determined by high-pressure liquid chromatography (HPLC) with ultraviolet (UV) detection. Pharmacokinetic variables were calculated using a two-compartment model with first order elimination which best fit the data. The mean volume of distribution at steady-state, distribution half-life, and elimination half-life were 898.25 ml/kg, 0.16 hr, 1.79 hr, respectively. No adverse effects were noted after IV administration.


Assuntos
Antibacterianos/farmacocinética , Clindamicina/análogos & derivados , Macropodidae/metabolismo , Animais , Antibacterianos/administração & dosagem , Antibacterianos/sangue , Cromatografia Líquida de Alta Pressão/veterinária , Clindamicina/administração & dosagem , Clindamicina/sangue , Clindamicina/farmacocinética , Feminino , Meia-Vida , Infusões Intravenosas/veterinária , Masculino
17.
Proc Biol Sci ; 283(1842)2016 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-27807264

RESUMO

In jawed vertebrates, genes of the major histocompatibility complex (MHC) play a key role in immunity by encoding cell-surface proteins that recognize and bind non-self antigens. High variability at MHC suggests that these loci may also function in social signalling such as mate choice and kin recognition. This requires that MHC genotype covaries with some perceptible phenotypic trait. In mammals and fish, MHC is signalled chemically through volatile and non-volatile peptide odour cues, facilitating MHC-dependent mate choice and other behaviours. In birds, despite evidence for MHC-dependent mating, candidate mechanisms for MHC signalling remain largely unexplored. However, feather preen wax has recently been implicated as a potential source of odour cues. We examined whether the chemical composition of preen wax correlates with MHC class IIß genotypes of wild song sparrows (Melospiza melodia). Pairwise chemical distance reflected amino acid distance at MHC for male-female dyads, although not for same-sex dyads. Chemical diversity did not reflect MHC diversity. We used gas chromatography-mass spectrometry (GC-MS) to characterize preen wax compounds, and identified four wax esters that best reflect MHC similarity. Provided songbirds can detect variation in preen wax composition, this cue may allow individuals to assess MHC compatibility of potential mates.


Assuntos
Plumas/química , Complexo Principal de Histocompatibilidade , Aves Canoras/genética , Ceras/química , Animais , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Genótipo , Masculino , Odorantes
18.
Br J Surg ; 103(2): e29-46, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26771470

RESUMO

BACKGROUND: Ageing is the inevitable time-dependent decline in physiological organ function that eventually leads to death. Age is a major risk factor for many of the most common medical conditions, such as cardiovascular disease, cancer, diabetes and Alzheimer's disease. This study reviews currently known hallmarks of ageing and their clinical implications. METHODS: A literature search of PubMed/MEDLINE was conducted covering the last decade. RESULTS: Average life expectancy has increased dramatically over the past century and is estimated to increase even further. Maximum longevity, however, appears unchanged, suggesting a universal limitation to the human organism. Understanding the underlying molecular processes of ageing and health decline may suggest interventions that, if used at an early age, can prevent, delay, alleviate or even reverse age-related diseases. Hallmarks of ageing can be grouped into three main categories. The primary hallmarks cause damage to cellular functions: genomic instability, telomere attrition, epigenetic alterations and loss of proteostasis. These are followed by antagonistic responses to such damage: deregulated nutrient sensing, altered mitochondrial function and cellular senescence. Finally, integrative hallmarks are possible culprits of the clinical phenotype (stem cell exhaustion and altered intercellular communication), which ultimately contribute to the clinical effects of ageing as seen in physiological loss of reserve, organ decline and reduced function. CONCLUSION: The sum of these molecular hallmarks produces the clinical picture of the elderly surgical patient: frailty, sarcopenia, anaemia, poor nutrition and a blunted immune response system. Improved understanding of the ageing processes may give rise to new biomarkers of risk or prognosis, novel treatment targets and translational approaches across disciplines that may improve outcomes.


Assuntos
Envelhecimento/fisiologia , Células-Tronco Adultas/fisiologia , Envelhecimento/genética , Comunicação Celular/fisiologia , Senescência Celular/fisiologia , Epigênese Genética/fisiologia , Instabilidade Genômica/fisiologia , Humanos , Expectativa de Vida , Doenças Mitocondriais/etiologia , Fenômenos Fisiológicos da Nutrição/fisiologia , Deficiências na Proteostase/etiologia , Telômero/fisiologia
19.
Intern Med J ; 46(3): 332-8, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26748888

RESUMO

BACKGROUND: Despite recognised benefits of optimal glycaemic control in patients with type 1 diabetes mellitus (T1DM), good control is still difficult to achieve, particularly for adolescents and young adults. Recognition of factors that may assist early optimisation of glycaemic control is therefore important. AIMS: We explored associations of demographic, social and behavioural factors with glycosylated haemoglobin (HbA1c) levels in participants with T1DM aged 18-25 years. METHODS: A cross-sectional analysis was performed on young adults attending a dedicated multidisciplinary clinic at Fremantle Hospital, Western Australia from January to August 2014. RESULTS: Data from 93 participants were analysed. Mean age was 21.4 ± 2.3 years, and 39.8% of the cohort were female. Longer duration of diabetes was associated with higher HbA1c (r = 0.25, P = 0.04). Men had lower HbA1c than women (8.2 ± 1.6 vs 9.2 ± 2.0%, P = 0.01). Increased frequency of clinic attendance was associated with lower HbA1c (r = -0.27, P = 0.02). Those engaged in work or study had better HbA1c compared with those who were not (8.9 ± 2.1 vs 10.5 ± 2.1%, P = 0.03). Socioeconomic disadvantage, risk-taking behaviour, insulin pump use and distance travelled to clinic were not associated with differences in HbA1c. CONCLUSION: In young adults with T1DM, geographical separation, socioeconomic disadvantage and risk-taking behaviours did not influence glycaemic control. Longer duration of diabetes identifies young adults at higher risk of poor control, while attendance at a multidisciplinary clinic and engagement in work or study was associated with better glycaemic control. Additional studies are warranted to clarify the role of behavioural interventions to improve diabetes management in young adults.


Assuntos
Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/psicologia , Emprego , Índice Glicêmico/fisiologia , Assunção de Riscos , Adolescente , Adulto , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Estudos de Coortes , Estudos Transversais , Diabetes Mellitus Tipo 1/epidemiologia , Emprego/tendências , Feminino , Índice Glicêmico/efeitos dos fármacos , Humanos , Insulina/administração & dosagem , Masculino , Austrália Ocidental/epidemiologia , Adulto Jovem
20.
Phys Rev Lett ; 114(11): 117201, 2015 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-25839304

RESUMO

Cd(3)As(2) is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and nonsaturating linear magnetoresistance that may be relevant for future practical applications. We report magnetotransport and tunnel diode oscillation measurements on Cd(3)As(2), in magnetic fields up to 65 T and temperatures between 1.5 and 300 K. We find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility rather than directly linked to Fermi surface changes even when approaching the quantum limit. From the observed quantum oscillations, we determine the bulk three-dimensional Fermi surface having signatures of Dirac behavior with a nontrivial Berry phase shift, very light effective quasiparticle masses, and clear deviations from the band-structure predictions. In very high fields we also detect signatures of large Zeeman spin splitting (g∼16).

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