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1.
J Dairy Sci ; 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38642653

RESUMO

In countries with pasture-based dairy systems and relatively cold winters, such as New Zealand, it is common to manage pregnant, nonlactating cows on forage crop paddocks rather than pasture due to slow pasture growth rates. Wintering dairy cattle on grazed crops can compromise welfare if wet and muddy underfoot conditions occur, which can reduce lying. This study investigated behavioral and physiological indicators of welfare of cows under 2 wintering practices: cows managed on and grazed kale crop (Brassica oleracea), and cows managed on pasture with baled hay. Following dry-off (d 0), 80 cows were randomly assigned to one of the 2 wintering practices (40 cows/practice) and monitored between d 4 and d 32 (phase 1). During this period, lying and stepping behavior was continuously recorded using leg-based accelerometers. Blood samples were obtained at d 0 and 32 for measurements of thyroxine (T4), nonesterified fatty acids (NEFA), white blood cells (WBC), and red blood cells (RBC). All data for phase 1 were presented descriptively due to the lack of treatment replication. Daily mean air temperature during this period was 5.2°C (range: 0.0 to 10.7°C), and rainfall was 1.1mm/d (range: 0 to 5.6mm/d). Between d 4 and 32, cows in both groups spent similar amounts of time lying (pasture with hay cows: 8.9h/24h ± 2.57, kale crop cows: 8.7h/24h ± 3.06, mean ± SEM). Both groups reduced their lying on wet and cold days and there was evidence of rebound lying once unfavorable weather conditions stopped. Cows on kale crop had numerically higher NEFA and lower WBC compared with cows managed on pasture, although most physiological values were within normal ranges. In a second phase of the study (d 34 and 35), cows were managed under controlled, replicated conditions in the 2 wintering practices using typical on-farm stocking rates (2 or 4 cows per group in the pasture with hay and kale crop treatments, respectively; n = 10 groups/treatment). During this period, cow behavior, skin and surface temperatures, hygiene scores, feed intakes and ground conditions were measured. Weather conditions during the 48-h exposure were mostly cold and dry (mean air temperature: 7.8°C, range: -2.2 to 20.5°C). Cows managed on pasture with hay spent more time lying down on the first day of exposure, however, this was likely due to less space being available to kale cows on this day. Cows managed on pasture with hay ruminated more than cows on kale crop on both days of observations (Day 1: 37.9% vs 30.9% of observations, Day 2: 36.8% vs 28.7% of observations for pasture with hay and kale crop groups, respectively) and were lying more often in postures indicative of greater thermal comfort. Cows managed on pasture with hay had higher skin and surface temperatures compared with cows on kale crop, whereas cows on kale crop had dirtier coats. Results suggest that opportunities for thermal comfort were greater for cows managed on pasture with hay bales, which may be due to increased rumination activities and more insulated lying areas.

2.
Adv Exp Med Biol ; 1404: 195-211, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36792877

RESUMO

Vibrio cholerae, the agent of cholera, is a natural inhabitant of aquatic environments. Over the past decades, the importance of specific nutrients and micronutrients in the environmental survival, host colonization, and pathogenesis of this species has become increasingly clear. For instance, V. cholerae has evolved ingenious mechanisms that allow the bacterium to colonize and establish a niche in the intestine of human hosts, where it competes with commensals (gut microbiota) and other pathogenic bacteria for available nutrients. Here, we discuss the carbon and energy sources utilized by V. cholerae and what is known about the role of nutrition in V. cholerae colonization. We examine how nutritional signals affect virulence gene regulation and how interactions with intestinal commensal species can affect intestinal colonization.


Assuntos
Cólera , Vibrio cholerae , Humanos , Vibrio cholerae/genética , Cólera/microbiologia , Intestinos/microbiologia , Virulência , Nutrientes , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica
3.
Blood ; 136(22): 2535-2547, 2020 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-32589703

RESUMO

Expansion of human hematopoietic stem cells (HSCs) is a rapidly advancing field showing great promise for clinical applications. Recent evidence has implicated the nervous system and glial family ligands (GFLs) as potential drivers of hematopoietic survival and self-renewal in the bone marrow niche; how to apply this process to HSC maintenance and expansion has yet to be explored. We show a role for the GFL receptor, RET, at the cell surface of HSCs in mediating sustained cellular growth, resistance to stress, and improved cell survival throughout in vitro expansion. HSCs treated with the key RET ligand/coreceptor complex, glial-derived neurotrophic factor and its coreceptor, exhibit improved progenitor function at primary transplantation and improved long-term HSC function at secondary transplantation. Finally, we show that RET drives a multifaceted intracellular signaling pathway, including key signaling intermediates protein kinase B, extracellular signal-regulated kinase 1/2, NF-κB, and p53, responsible for a wide range of cellular and genetic responses that improve cell growth and survival under culture conditions.


Assuntos
Proliferação de Células , Células-Tronco Hematopoéticas/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas Proto-Oncogênicas c-ret/metabolismo , Animais , Técnicas de Cultura de Células , Sobrevivência Celular , Ativação Enzimática , Feminino , Células-Tronco Hematopoéticas/citologia , Humanos , Masculino , Camundongos
4.
J Dairy Sci ; 99(12): 9925-9930, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27743667

RESUMO

Indwelling rumen temperature bolus (RTB) systems have the potential to offer a convenient and timely method of detecting pyrexia, indicative of active infectious disease. The aim of this pilot study was to evaluate the utility of using RTB systems in preweaned dairy calves. First, an in vitro study was performed to evaluate the accuracy of the RTB in its immediate environment. Thirteen RTB were immersed in a hot water bath (WB). Variably collected RTB temperatures were then matched to WB temperatures, which varied from 36 to 41°C, with 1h spent at each temperature. Second, an in vivo study was performed to evaluate the ability of the RTB to predict a rectal thermometer (RT) temperature. Ten healthy heifer calves less than 1wk of age were administered an RTB. Rectal thermometer and matched RTB temperatures were taken hourly, over a 6-h period, 1 day per week during wk 1, 3, 5, 7, and 9 of age. During each 6-h observation period, calves were offered both water and milk feedings and temperatures recorded every 15min for 1h thereafter. For both studies, the relationship between RTB and one of WB (in vitro) or RT temperature (in vivo) was described by calculating a concordance correlation coefficient (CCC) and by use of a multivariable linear regression model with repeated measures. For the in vivo study, the model also controlled for week and breed. Diagnostic test characteristics were calculated for the ability of individual RTB measures to detect pyrexia (RT ≥39.5°C). For the in vitro study, the association between the RTB and a known temperature was strong (CCC=0.95), but the RTB measures underestimated the temperature of the water bath by 0.43±0.08°C. For the in vivo study, the association between RT and the RTB temperature measurement in a calf was weaker (CCC=0.29); the average RTB temperature was 0.33±0.06°C lower than the RT temperature. The sensitivity (29%) and positive predictive value (17%) of using individual RTB measures to detect a fever was low. The results of this pilot study suggest that an individual RTB measurement may not be a good diagnostic test to detect pyrexia in calves.


Assuntos
Doenças dos Bovinos/diagnóstico , Indústria de Laticínios/métodos , Febre/veterinária , Rúmen/fisiopatologia , Temperatura , Animais , Bovinos , Doenças dos Bovinos/fisiopatologia , Feminino , Febre/diagnóstico , Febre/fisiopatologia , Projetos Piloto
5.
Gen Dent ; 63(5): 33-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26325639

RESUMO

The aim of this study was to evaluate, using microcomputed tomography (µCT), the frequency of conjoined mesial canals in first and second mandibular molars with a single distal canal. Mandibular first (n = 114) and second molars (n = 114) with mature apices were randomly selected from a pool of extracted teeth. The specimens were decoronated to establish clinically the existence of a single distal canal. Teeth with C-shaped canals were discarded. Each tooth was scanned with a µCT system and evaluated in 3 dimensions. Of 228 examined teeth, 206 were included in the study. Of these, 129 (62.6%) displayed conjoined mesial canals with a single portal of exit, and 77 (37.4%) displayed 2 distinct mesial canals with 2 separate portals of exit. Of the teeth with conjoined mesial canals, 71 (55.0%) were second molars and 58 (45.0%) were first molars. Conjoined mesial canals exhibited a mean interorifice distance of less than 3.00 mm. These data regarding morphological patterns alert clinicians to the possible need to modify endodontic techniques in mandibular molars with single distal canals.


Assuntos
Cavidade Pulpar/anormalidades , Dente Molar/anormalidades , Microtomografia por Raio-X , Cavidade Pulpar/diagnóstico por imagem , Humanos , Mandíbula , Dente Molar/diagnóstico por imagem , Tratamento do Canal Radicular/métodos , Raiz Dentária/anormalidades , Raiz Dentária/diagnóstico por imagem
6.
Nature ; 447(7143): 487-92, 2007 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-17495930

RESUMO

Reactive oxygen species trigger cellular responses by activation of stress-responsive mitogen-activated protein kinase (MAPK) signalling pathways. Reversal of MAPK activation requires the transcriptional induction of specialized cysteine-based phosphatases that mediate MAPK dephosphorylation. Paradoxically, oxidative stresses generally inactivate cysteine-based phosphatases by thiol modification and thus could lead to sustained or uncontrolled MAPK activation. Here we describe how the stress-inducible MAPK phosphatase, Sdp1, presents an unusual solution to this apparent paradox by acquiring enhanced catalytic activity under oxidative conditions. Structural and biochemical evidence reveals that Sdp1 employs an intramolecular disulphide bridge and an invariant histidine side chain to selectively recognize a tyrosine-phosphorylated MAPK substrate. Optimal activity critically requires the disulphide bridge, and thus, to the best of our knowledge, Sdp1 is the first example of a cysteine-dependent phosphatase that couples oxidative stress with substrate recognition. We show that Sdp1, and its paralogue Msg5, have similar properties and belong to a new group of phosphatases unique to yeast and fungal taxa.


Assuntos
Fungos/enzimologia , Proteínas Tirosina Fosfatases/classificação , Proteínas Tirosina Fosfatases/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Catálise , Cisteína/metabolismo , Dissulfetos/metabolismo , Fosfatases de Especificidade Dupla , Histidina/metabolismo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Oxirredução/efeitos dos fármacos , Estresse Oxidativo , Fosfoproteínas Fosfatases/química , Fosfoproteínas Fosfatases/classificação , Fosfoproteínas Fosfatases/metabolismo , Fosfotirosina/metabolismo , Proteínas Tirosina Fosfatases/química , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/classificação , Proteínas de Saccharomyces cerevisiae/metabolismo , Especificidade por Substrato
7.
Nat Commun ; 14(1): 7551, 2023 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-37985758

RESUMO

Glial-cell line derived neurotrophic factor (GDNF) bound to its co-receptor GFRα1 stimulates the RET receptor tyrosine kinase, promoting neuronal survival and neuroprotection. The GDNF-GFRα1 complex also supports synaptic cell adhesion independently of RET. Here, we describe the structure of a decameric GDNF-GFRα1 assembly determined by crystallography and electron microscopy, revealing two GFRα1 pentamers bridged by five GDNF dimers. We reconsitituted the assembly between adhering liposomes and used cryo-electron tomography to visualize how the complex fulfils its membrane adhesion function. The GFRα1:GFRα1 pentameric interface was further validated both in vitro by native PAGE and in cellulo by cell-clustering and dendritic spine assays. Finally, we provide biochemical and cell-based evidence that RET and heparan sulfate cooperate to prevent assembly of the adhesion complex by competing for the adhesion interface. Our results provide a mechanistic framework to understand GDNF-driven cell adhesion, its relationship to trophic signalling, and the central role played by GFRα1.


Assuntos
Fator Neurotrófico Derivado de Linhagem de Célula Glial , Proteínas Proto-Oncogênicas c-ret , Proteínas Proto-Oncogênicas c-ret/genética , Proteínas Proto-Oncogênicas c-ret/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais
8.
J Dairy Sci ; 95(1): 83-90, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22192186

RESUMO

Up to 3% of young children develop milk allergy and this may influence the development of immune-mediated diseases in later life. One protein that has been associated with allergic reactions to ruminant milk is α(S1)-casein (CN). Studies suggest that goat milk with low levels of α(S1)-CN may reduce allergenicity of milk, but the dose response to α(S1)-CN has not been confirmed. In this study, we examined the immune response to varying levels of goat α(S1)-CN in a mouse model of gastrointestinal allergy. BALB/c mice (aged 5 wk) were given intraperitoneal injections with α(S1)-CN and aluminum as adjuvant at 1 and 3 wk to sensitize mice to the antigen. In wk 5, groups of fasting mice (n=8/group) were challenged 4 times on alternate days by intragastric gavage with saline or 2, 10, or 20mg of α(S1)-CN. Serum levels of specific IgE, IgG(1), and IgG(2a) antibodies and mouse mast cell protease-I were determined. Interleukin-4, IL-10, and IFN-γ responses to 48-h activation with antigen were measured in cultured splenocytes. We determined that mice sensitized with α(S1)-CN had higher titers of specific IgG(1) and IgE antibodies compared with controls; however, groups challenged with differing doses of α(S1)-CN did not differ. The group challenged with the highest dose of α(S1)-CN had a 10-fold increase in mouse mast cell protease-I compared with the group challenged with saline. Both IL-4 and IL-10 were produced in a dose-dependent manner by cultured splenocytes incubated with α(S1)-CN. Overall, α(S1)-CN stimulated the production of cytokines associated with allergic disease in a dose-dependent manner. Thus, milk with lower levels of α(S1)-CN should contribute to a lesser antigenic burden.


Assuntos
Caseínas/imunologia , Trato Gastrointestinal/imunologia , Hipersensibilidade a Leite/etiologia , Animais , Caseínas/farmacologia , Modelos Animais de Doenças , Relação Dose-Resposta Imunológica , Feminino , Trato Gastrointestinal/efeitos dos fármacos , Cabras , Imunoglobulina E/sangue , Imunoglobulina G/sangue , Interferon gama/sangue , Interleucina-10/sangue , Interleucina-4/sangue , Camundongos , Camundongos Endogâmicos BALB C , Hipersensibilidade a Leite/imunologia
9.
Ergonomics ; 53(2): 164-83, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20099172

RESUMO

This paper presents the findings of research relating to the specification of a new human factors report, conducted as part of the work requirements for the Human Integration into the Lifecycle of Aviation Systems project, sponsored by the European Commission. Specifically, it describes the proposed concept for a unique report, which will form the basis for all operational and safety reports completed by flight crew. This includes all mandatory and optional reports. Critically, this form is central to the advancement of improved processes and technology tools, supporting airline performance management, safety management, organisational learning and knowledge integration/information-sharing activities. Specifically, this paper describes the background to the development of this reporting form, the logic and contents of this form and how reporting data will be made use of by airline personnel. This includes a description of the proposed intelligent planning process and the associated intelligent flight plan concept, which makes use of airline operational and safety analyses information. Primarily, this new reporting form has been developed in collaboration with a major Spanish airline. In addition, it has involved research with five other airlines. Overall, this has involved extensive field research, collaborative prototyping and evaluation of new reports/flight plan concepts and a number of evaluation activities. Participants have included both operational and management personnel, across different airline flight operations processes. Statement of Relevance: This paper presents the development of a reporting concept outlined through field research and collaborative prototyping within an airline. The resulting reporting function, embedded in the journey log compiled at the end of each flight, aims at enabling employees to audit the operations of the company they work for.


Assuntos
Aviação/normas , Ergonomia , Notificação de Abuso , Gestão da Segurança/métodos , Humanos
10.
Phys Rev E ; 101(1-1): 013101, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32069619

RESUMO

A numerical procedure based on the Schwarz-Christoffel map suitable for the study of the Laplacian growth of thin two-dimensional protrusions is presented. The protrusions take the form of either straight needles or curved fingers satisfying Loewner's equation, and are represented by slits in the complex plane. Particular use is made of Driscoll's numerical procedure, the SC Toolbox, for computing the Schwarz-Christoffel map from a half plane to a slit half plane. Since the Schwarz-Christoffel map applies only to polygonal regions, the growth of curved fingers is approximated by an increasing number of short straight line segments. The growth rate is given by a fixed power η of the harmonic measure at the finger or needle tips and so includes the possibility of "screening" as the needles of fingers interact with themselves and with boundaries. The method is illustrated with examples of multiple needle and finger growth in half-plane and channel geometries. The effect of η on the trajectories of asymmetric bifurcating fingers is also studied.

11.
Science ; 182(4118): 1243-7, 1973 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-17811318

RESUMO

Palynologically productive localities have been found in the United States throughout the Newark Group basins, most of which had previously been assumed to be barren. Rich palynoflorules dominated by coniferous pollen of Circulina-Classopollis type, and well-preserved fossil fishes, including possible new semionotids, have been found in the Hartford basin. Palynological data indicate that the Newark Group has considerable time-stratigraphic range: Upper Triassic for the Cumnock Formation (North Carolina), the Vinita Beds (Virginia), and the upper New Oxford Formation (Pennsylvania), Rhaeto-Liassic for the Brunswick Formation (New Jersey), Portland Formation (Connecticut and Massachusetts), and the Shuttle Meadow Formation (Connecticut).

12.
Trends Biochem Sci ; 18(2): 48-52, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8488558

RESUMO

Recent studies on nerve growth factor have revealed important new insights into the structure, function and evolution of this prototypical neurotrophic factor. Some of its features are (1) it has a unique three-dimensional fold that has since been found in two other growth factors, (2) it uses the trk proto-oncogene product, which has a tyrosine kinase, as a receptor and (3) it shares homology with at least three other factors, now collectively called neurotrophins, which have a spectrum of target cells.


Assuntos
Fatores de Crescimento Neural/química , Sequência de Aminoácidos , Animais , Humanos , Dados de Sequência Molecular , Fatores de Crescimento Neural/genética , Conformação Proteica , Proto-Oncogene Mas , Receptores de Fator de Crescimento Neural/química , Relação Estrutura-Atividade
13.
Trends Biochem Sci ; 24(3): 116-20, 1999 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10203759

RESUMO

DNA tumour viruses deregulate the mammalian cell cycle to provide a better environment for their replication. Studies of such deregulation have led to the identification of key regulatory steps that normally control the G1-S phase transition of the cell cycle. The balance between the activities of G1-specific cyclin-CDK complexes and their inhibitors is critical. Recent studies suggest that certain herpesviruses disrupt this balance: the viruses encode a cyclin that generates active complexes even in the presence of high inhibitor levels.


Assuntos
Proteínas de Ciclo Celular , Quinases Ciclina-Dependentes/antagonistas & inibidores , Ciclinas/fisiologia , Herpesviridae/fisiologia , Proteínas Supressoras de Tumor , Ciclo Celular , Inibidor p16 de Quinase Dependente de Ciclina/fisiologia , Inibidor de Quinase Dependente de Ciclina p21 , Inibidor de Quinase Dependente de Ciclina p27 , Herpesviridae/patogenicidade , Humanos , Proteínas Associadas aos Microtúbulos/fisiologia , Modelos Biológicos , Modelos Moleculares , Replicação Viral
14.
Infant Behav Dev ; 57: 101337, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31450025

RESUMO

Behavioral signs of Autism Spectrum Disorder (ASD) are typically observable by the second year of life and a reliable diagnosis of ASD is possible by 2 to 3 years of age. Studying infants with familial risk for ASD allows for the investigation of early signs of ASD risk within the first year. Brain abnormalities such as hyper-connectivity within the first year may precede the overt signs of ASD that emerge later in life. In this preliminary study, we use functional near-infrared spectroscopy (fNIRS), an infant-friendly neuroimaging tool that is relatively robust against motion artifacts, to examine functional activation and connectivity during naturalistic social interactions in 9 high-risk (HR; older sibling with ASD) and 6 low-risk (LR; no family history of ASD) infants from 6 to 9 months of age. We obtained two 30-second baseline periods and a 5-minute social interaction period. HR infants showed reduced right and left-hemispheric activation compared to LR infants based on oxy (HbO2) and deoxy (HHb) signal trends. HR infants also had greater functional connectivity than LR infants during the pre- and post-social periods and showed a drop in connectivity during the social period. Our findings are consistent with previous work suggesting early differences in cortical activation associated with familial risk for ASD, and highlight the promise of fNIRS in evaluating potential markers of ASD risk during naturalistic social contexts.


Assuntos
Transtorno do Espectro Autista/diagnóstico por imagem , Transtorno do Espectro Autista/genética , Córtex Cerebral/diagnóstico por imagem , Predisposição Genética para Doença/genética , Relações Interpessoais , Rede Nervosa/diagnóstico por imagem , Transtorno do Espectro Autista/psicologia , Feminino , Predisposição Genética para Doença/psicologia , Humanos , Lactente , Masculino , Relações Pais-Filho , Estudo de Prova de Conceito , Fatores de Risco , Irmãos/psicologia , Espectroscopia de Luz Próxima ao Infravermelho/métodos
15.
Aliment Pharmacol Ther ; 48(4): 423-430, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29971829

RESUMO

BACKGROUND: Hyaluronic acid is a recognised noninvasive marker of liver fibrosis. However, its prognostic ability has not been extensively studied. AIMS: To investigate the ability of an index serum hyaluronic acid measurement to independently predict transplant-free survival in patients with liver disease of varying aetiology and severity. METHODS: This was a retrospective single-centre cohort study. Serum hyaluronic acid was measured at the discretion of the attending clinicians, in patients attending the liver clinic, to assess disease severity. Patients with a hyaluronic acid measurement between 1995 and 2010 were identified. Patient characteristics at the point of hyaluronic acid measurement were recorded from medical records. Follow-up was from date of index hyaluronic acid measurement to date of death, date of transplant or censor date (July 01, 2015). Primary outcomes were all-cause and liver-related mortality. Kaplan-Meier analysis was used to compare survival in 3 patient groups with hyaluronic acid levels of <100 µg/L, 100-300 µg/L and >300 µg/L. Survival models were constructed using Cox proportional hazard and prediction accuracy was assessed by Harrell's C-statistic. RESULTS: Five hundred and eighty nine patients fulfilled inclusion criteria. Median follow-up was 5.6 years (range 0.1-19.7). Transplant-free survival was significantly different between patients with hyaluronic acid <100 µg/L, 100-300 µg/L and >300 µg/L for liver-related as well as all-cause mortality (P < 0.001). Hyaluronic acid level was an independent predictor of survival (liver-related: HR 1.39, 95% CI 1.20-1.60, P < 0.001; all-cause: HR 1.04, 95% CI 1.02-1.06, P = 0.001). The liver-related prediction accuracy of hyaluronic acid was 0.74 (Standard error 0.03). CONCLUSION: Index hyaluronic acid measurement can accurately and independently predict liver-related and all-cause mortality in patients with liver disease.


Assuntos
Biomarcadores/sangue , Ácido Hialurônico/sangue , Cirrose Hepática/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/análise , Estudos de Coortes , Feminino , Seguimentos , Sobrevivência de Enxerto , Humanos , Ácido Hialurônico/análise , Estimativa de Kaplan-Meier , Cirrose Hepática/sangue , Cirrose Hepática/mortalidade , Cirrose Hepática/terapia , Transplante de Fígado/efeitos adversos , Transplante de Fígado/mortalidade , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Estudos Retrospectivos , Adulto Jovem
16.
Aliment Pharmacol Ther ; 47(5): 631-644, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29271504

RESUMO

BACKGROUND: Validated diagnostic tools that are accurate, cost effective and acceptable to patients are required for disease stratification and monitoring in NAFLD. AIMS: To investigate the performance and cost of multiparametric MRI alongside existing biomarkers in the assessment of NAFLD. METHODS: Adult patients undergoing standard of care liver biopsy for NAFLD were prospectively recruited at two UK liver centres and underwent multiparametric MRI, blood sampling and transient elastography withing 2 weeks of liver biopsy. Non-invasive markers were compared to histology as the gold standard. RESULTS: Data were obtained in 50 patients and 6 healthy volunteers. Corrected T1 (cT1) correlated with NAFLD activity score (ρ = 0.514, P < .001). cT1, enhanced liver fibrosis (ELF) test and liver stiffness differentiated patients with simple steatosis and NASH with AUROC (95% CI) of 0.69 (0.50-0.88), 0.87 (0.77-0.79) and 0.82 (0.70-0.94) respectively and healthy volunteers from patients with AUROC (95% CI) of 0.93 (0.86-1.00), 0.81 (0.69-0.92) and 0.89 (0.77-1.00) respectively. For the risk stratification of NAFLD, multiparametric MRI could save £150,218 per 1000 patients compared to biopsy. Multiparametric MRI did not discriminate between individual histological fibrosis stages in this population (P = .068). CONCLUSIONS: Multiparametric MRI accurately identified patients with steatosis, stratifies those with NASH or simple steatosis and reliably excludes clinically significant liver disease with superior negative predictive value (83.3%) to liver stiffness (42.9%) and ELF (57.1%). For the risk stratification of NAFLD, multiparametric MRI was cost effective and, combined with transient elastography, had the lowest cost per correct diagnosis.


Assuntos
Fígado/diagnóstico por imagem , Imageamento por Ressonância Magnética , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Adolescente , Adulto , Idoso , Biópsia , Análise Custo-Benefício , Técnicas de Imagem por Elasticidade/economia , Técnicas de Imagem por Elasticidade/métodos , Feminino , Voluntários Saudáveis , Humanos , Fígado/patologia , Cirrose Hepática/diagnóstico , Cirrose Hepática/economia , Imageamento por Ressonância Magnética/economia , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/economia , Hepatopatia Gordurosa não Alcoólica/patologia , Valor Preditivo dos Testes , Adulto Jovem
17.
Curr Opin Struct Biol ; 6(5): 611-6, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8913682

RESUMO

The widespread application of multiwavelength anomalous diffraction (MAD) for phase evaluation has been hampered in the past by the small selection of anomalous scattering centres that could be introduced into macromolecules. Recently, the use of chemical modification, protein engineering or biosynthetic labelling has provided suitable tools to overcome the previous limitations, thereby making most structural analyses amenable to a MAD approach.


Assuntos
Engenharia de Proteínas , Proteínas/química , Animais , Cristalografia por Raios X , Humanos
18.
19.
Structure ; 3(10): 1109-19, 1995 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-8590005

RESUMO

BACKGROUND: beta-bungarotoxin is a heterodimeric neurotoxin consisting of a phospholipase subunit linked by a disulfide bond to a K+ channel binding subunit which is a member of the Kunitz protease inhibitor superfamily. Toxicity, characterized by blockage of neural transmission, is achieved by the lipolytic action of the phospholipase targeted to the presynaptic membrane by the Kunitz module. RESULTS: The crystal structure at 2.45 A resolution suggests that the ion channel binding region of the Kunitz subunit is at the opposite end of the module from the loop typically involved in protease binding. Analysis of the phospholipase subunit reveals a partially occluded substrate-binding surface and reduced hydrophobicity. CONCLUSIONS: Molecular recognition by this Kunitz module appears to diverge considerably from more conventional superfamily members. The ion channel binding region identified here may mimic the regulatory interaction of endogenous neuropeptides. Adaptations of the phospholipase subunit make it uniquely suited to targeting and explain the remarkable ability of the toxin to avoid binding to non-target membranes. Insight into the mechanism of beta-bungarotoxin gained here may lead to the development of therapeutic strategies against not only pathological cells, but also enveloped viruses.


Assuntos
Bungarotoxinas/química , Fosfolipases/metabolismo , Canais de Potássio/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Bungarotoxinas/metabolismo , Cristalografia por Raios X , Venenos Elapídicos/química , Modelos Moleculares , Dados de Sequência Molecular , Fenotiazinas/química , Conformação Proteica , Homologia de Sequência de Aminoácidos
20.
Structure ; 5(10): 1275-85, 1997 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-9351801

RESUMO

BACKGROUND: Nerve growth factor (NGF) is a neurotrophic factor that promotes the differentiation and survival of certain populations of neurons in the central and peripheral nervous systems. 7S NGF is an alpha 2 beta 2 gamma 2 complex in which the beta-NGF dimer (the active neurotrophin) is associated with two alpha-NGF and two gamma-NGF subunits, which belong to the glandular kallikrein family of serine proteinases. The gamma-NGF subunit is an active serine proteinase capable of processing the precursor form of beta-NGF, whereas alpha-NGF is an inactive serine proteinase. The structure of 7S NGF could be used as a starting point to design inhibitors that prevent NGF binding to its receptors, as a potential treatment of neurodegenerative diseases. RESULTS: The crystal structure of 7S NGF shows that the two gamma-NGF subunits make extensive interactions with each other around the twofold axis of the complex and have the C-terminal residues of the beta-NGF subunits bound within their active sites. The 'activation domain' of each of the alpha-NGF subunits is in an inactive (zymogen-like) conformation and makes extensive interactions with the beta-NGF dimer. The two zinc ions that stabilize the complex are located at the relatively small interfaces between the alpha-NGF and gamma-NGF subunits. CONCLUSIONS: The structure of 7S NGF shows how the twofold axis of the central beta-NGF dimer organizes the symmetry of this multisubunit growth factor complex. The extensive surface of beta-NGF buried within the 7S complex explains the lack of neurotrophic activity observed for 7S NGF. The regions of the beta-NGF dimer that contact the alpha-NGF subunits overlap with those known to engage NGF receptors. Two disulphide-linked loops on alpha-NGF make multiple interactions with beta-NGF and suggest that it might be possible to design peptides that inhibit the binding of beta-NGF to its receptors.


Assuntos
Fatores de Crescimento Neural/química , Serina Endopeptidases/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cristalografia por Raios X , Dimerização , Precursores Enzimáticos/química , Calicreínas/química , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Fatores de Crescimento Neural/metabolismo , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Alinhamento de Sequência , Serina Endopeptidases/metabolismo , Zinco/química , Zinco/metabolismo
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