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1.
Ultrasound Obstet Gynecol ; 62(5): 739-746, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-36920431

RESUMEN

OBJECTIVE: Two-dimensional (2D) transvaginal ultrasound (TVS) is an accessible and cost-effective diagnostic tool for the detection of adenomyosis. Different ultrasound features related to adenomyosis have been described, but the predictive value of each ultrasound sign and their combinations requires further investigation. We aimed to analyze the accuracy of 2D-TVS and describe possible combinations of ultrasound signs with a high predictive value in the diagnosis of adenomyosis. METHODS: This was a prospective multicenter study of patients scheduled for laparoscopic hysterectomy who had been examined using standardized 2D-TVS at nine expert centers specializing in the diagnosis and treatment of endometriosis. 2D-TVS examination included nine typical adenomyosis ultrasound features, comprising heterogeneous myometrium, myometrial linear striations, myometrial cysts, subendometrial microcysts, asymmetrical myometrial thickening, uterine enlargement, the 'question mark sign', thickening of the junctional zone and hyperechoic myometrial spots, in order to predict or exclude the presence of adenomyosis. Ultrasound examination results were compared with histology after hysterectomy. The diagnostic reliability of the nine ultrasound signs and their combinations, and the influence of concurrent fibroids on the accuracy of the results, were analyzed. RESULTS: A total of 202 patients were enrolled into the study. Histopathological examination revealed adenomyosis in 130 patients (64.4%). The accuracy of prediction of adenomyosis by 2D-TVS examination using all signs was 63.4% (positive predictive value, 71.5%; negative predictive value, 48.6%; sensitivity, 71.5%; specificity, 48.6%). Heterogeneous myometrium, myometrial cysts, subendometrial microcysts and hyperechoic myometrial spots showed the highest accuracy (55.7-62.1%) as individual ultrasound signs for the prediction of adenomyosis. The combination of the most accurate ultrasound signs (subendometrial microcysts, myometrial cysts and heterogeneous myometrium) improved the specificity of prediction (86.1%) when compared with that of these three single markers (35.2-81.7%). Uterine enlargement and asymmetry showed both low sensitivity (60.8% and 52.3%, respectively) and specificity (41.7% and 49.3%, respectively) as individual sonographic signs. CONCLUSIONS: Heterogeneous myometrium, myometrial cysts, subendometrial microcysts and hyperechoic myometrial spots showed the highest accuracy for the detection of adenomyosis in this study, while uterine enlargement and asymmetry led to high false-positive and false-negative results. A combination of ultrasound features including the most accurate signs increases specificity. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.


Asunto(s)
Adenomiosis , Quistes , Endometriosis , Femenino , Humanos , Adenomiosis/diagnóstico por imagen , Endometriosis/diagnóstico por imagen , Endometriosis/patología , Miometrio/diagnóstico por imagen , Miometrio/patología , Estudios Prospectivos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Ultrasonografía/métodos
2.
Proc Natl Acad Sci U S A ; 114(2): 328-333, 2017 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-28003462

RESUMEN

Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro systems have limitations, such as residual solvent and unphysiologically high membrane tension. Cell-sized giant unilamellar vesicles (GUVs) would be ideal for in vitro electrophysiology, but efforts to measure the membrane current of intact GUVs have been unsuccessful. In this work, two challenges for obtaining the "whole-GUV" patch-clamp configuration were identified and resolved. First, unless the patch pipette and GUV pressures are precisely matched in the GUV-attached configuration, breaking the patch membrane also ruptures the GUV. Second, GUVs shrink irreversibly because the membrane/glass adhesion creating the high-resistance seal (>1 GΩ) continuously pulls membrane into the pipette. In contrast, for cell-derived giant plasma membrane vesicles (GPMVs), breaking the patch membrane allows the GPMV contents to passivate the pipette surface, thereby dynamically blocking membrane spreading in the whole-GMPV mode. To mimic this dynamic passivation mechanism, beta-casein was encapsulated into GUVs, yielding a stable, high-resistance, whole-GUV configuration for a range of membrane compositions. Specific membrane capacitance measurements confirmed that the membranes were truly solvent-free and that membrane tension could be controlled over a physiological range. Finally, the potential for ion transport studies was tested using the model ion channel, gramicidin, and voltage-clamp fluorometry measurements were performed with a voltage-dependent fluorophore/quencher pair. Whole-GUV patch-clamping allows ion transport and other voltage-dependent processes to be studied while controlling membrane composition, tension, and shape.

3.
Haemophilia ; 23(2): 255-263, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-28205285

RESUMEN

BACKGROUND: Development of inhibitors is the most serious complication in haemophilia A treatment. The assessment of risk for inhibitor formation in new or modified factor concentrates is traditionally performed in previously treated patients (PTPs). However, evidence on risk factors for and natural history of inhibitors has been generated mostly in previously untreated patients (PUPs). The purpose of this study was to examine cases of de novo inhibitors in PTPs reported in the scientific literature and to the EUropean HAemophilia Safety Surveillance (EUHASS) programme, and explore determinants and course of inhibitor development. METHODS: We used a case series study design and developed a case report form to collect patient level data; including detection, inhibitor course, treatment, factor VIII products used and events that may trigger inhibitor development (surgery, vaccination, immune disorders, malignancy, product switch). RESULTS: We identified 19 publications that reported 38 inhibitor cases and 45 cases from 31 EUHASS centres. Individual patient data were collected for 55/83 (66%) inhibitor cases out of 12 330 patients. The median (range) peak inhibitor titre was 4.4 (0.5-135.0), the proportion of transient inhibitors was 33% and only two cases of 12 undergoing immune tolerance induction failed this treatment. In the two months before inhibitor development, surgery was reported in nine (22%) cases, and high intensity treatment periods reported in seven (17%) cases. CONCLUSIONS: By studying the largest cohort of inhibitor development in PTPs assembled to date, we showed that inhibitor development in PTPs, is on average, a milder event than in PUPs.


Asunto(s)
Historia Natural/métodos , Adulto , Hemofilia A/tratamiento farmacológico , Humanos , Persona de Mediana Edad , Factores de Riesgo
4.
Proc Natl Acad Sci U S A ; 108(31): 12605-10, 2011 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-21768336

RESUMEN

Lipid and protein lateral mobility is essential for biological function. Our theoretical understanding of this mobility can be traced to the seminal work of Saffman and Delbrück, who predicted a logarithmic dependence of the protein diffusion coefficient (i) on the inverse of the size of the protein and (ii) on the "membrane size" for membranes of finite size [Saffman P, Delbrück M (1975) Proc Natl Acad Sci USA 72:3111-3113]. Although the experimental proof of the first prediction is a matter of debate, the second has not previously been thought to be experimentally accessible. Here, we construct just such a geometrically confined membrane by forming lipid bilayer nanotubes of controlled radii connected to giant liposomes. We followed the diffusion of individual molecules in the tubular membrane using single particle tracking of quantum dots coupled to lipids or voltage-gated potassium channels KvAP, while changing the membrane tube radius from approximately 250 to 10 nm. We found that both lipid and protein diffusion was slower in tubular membranes with smaller radii. The protein diffusion coefficient decreased as much as 5-fold compared to diffusion on the effectively flat membrane of the giant liposomes. Both lipid and protein diffusion data are consistent with the predictions of a hydrodynamic theory that extends the work of Saffman and Delbrück to cylindrical geometries. This study therefore provides strong experimental support for the ubiquitous Saffman-Delbrück theory and elucidates the role of membrane geometry and size in regulating lateral diffusion.


Asunto(s)
Membrana Dobles de Lípidos/metabolismo , Lípidos de la Membrana/metabolismo , Proteínas de la Membrana/metabolismo , Liposomas Unilamelares/metabolismo , Algoritmos , Animales , Transporte Biológico , Biotina/química , Células Cultivadas , Difusión , Glicosilfosfatidilinositoles/química , Proteínas Fluorescentes Verdes/química , Proteínas Fluorescentes Verdes/metabolismo , Membrana Dobles de Lípidos/química , Lípidos de la Membrana/química , Proteínas de la Membrana/química , Microscopía Fluorescente , Modelos Biológicos , Nanotubos , Fosfatidiletanolaminas/química , Polietilenglicoles/química , Canales de Potasio con Entrada de Voltaje/química , Canales de Potasio con Entrada de Voltaje/metabolismo , Ratas , Ratas Sprague-Dawley , Liposomas Unilamelares/química
5.
J Fish Biol ; 83(4): 766-803, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24090548

RESUMEN

Cryptic, not readily detectable, components of fishing mortality are not routinely accounted for in fisheries management because of a lack of adequate data, and for some components, a lack of accurate estimation methods. Cryptic fishing mortalities can cause adverse ecological effects, are a source of wastage, reduce the sustainability of fishery resources and, when unaccounted for, can cause errors in stock assessments and population models. Sources of cryptic fishing mortality are (1) pre-catch losses, where catch dies from the fishing operation but is not brought onboard when the gear is retrieved, (2) ghost-fishing mortality by fishing gear that was abandoned, lost or discarded, (3) post-release mortality of catch that is retrieved and then released alive but later dies as a result of stress and injury sustained from the fishing interaction, (4) collateral mortalities indirectly caused by various ecological effects of fishing and (5) losses due to synergistic effects of multiple interacting sources of stress and injury from fishing operations, or from cumulative stress and injury caused by repeated sub-lethal interactions with fishing operations. To fill a gap in international guidance on best practices, causes and methods for estimating each component of cryptic fishing mortality are described, and considerations for their effective application are identified. Research priorities to fill gaps in understanding the causes and estimating cryptic mortality are highlighted.


Asunto(s)
Conservación de los Recursos Naturales , Explotaciones Pesqueras/métodos , Peces , Animales , Explotaciones Pesqueras/instrumentación , Dinámica Poblacional , Conducta Predatoria , Estrés Fisiológico , Heridas y Lesiones/veterinaria
6.
Rev Fish Biol Fish ; 33(2): 475-499, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36404946

RESUMEN

Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these recent advances and provides strategic guidance for researchers aiming to characterise the occurrence of depredation, identify the shark species responsible, and test deterrent and management approaches to reduce its impacts. Specifically, the review covers the application of social science approaches, as well as advances in video camera and genetic methods for identifying depredating species. The practicalities and considerations for testing magnetic, electrical, and acoustic deterrent devices are discussed in light of recent research. Key concepts for the management of shark depredation are reviewed, with recommendations made to guide future research and policy development. Specific management responses to address shark depredation are lacking, and this review emphasizes that a "silver bullet" approach for mitigating depredation does not yet exist. Rather, future efforts to manage shark depredation must rely on a diverse range of integrated approaches involving those in the fishery (fishers, scientists and fishery managers), social scientists, educators, and other stakeholders.

7.
Traffic ; 11(12): 1519-29, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20887377

RESUMEN

To maintain cell membrane homeostasis, lipids must be dynamically redistributed during the formation of transport intermediates, but the mechanisms driving lipid sorting are not yet fully understood. Lowering sphingolipid concentration can reduce the bending energy of a membrane, and this effect could account for sphingolipid depletion along the retrograde pathway. However, sphingolipids and cholesterol are enriched along the anterograde pathway, implying that other lipid sorting mechanisms, such as protein-mediated sorting, can dominate. To characterize the influence of protein binding on the lipid composition of highly curved membranes, we studied the interactions of the B-subunit of Shiga toxin (STxB) with giant unilamellar vesicles containing its glycosphingolipid receptor [globotriaosylceramide (Gb3)]. STxB binding induced the formation of tubular membrane invaginations, and fluorescence microscopy images of these highly curved membranes were consistent with co-enrichment of Gb3 and sphingolipids. In agreement with theory, sorting was stronger for membrane compositions close to demixing. These results strongly support the hypothesis that proteins can indirectly mediate the sorting of lipids into highly curved transport intermediates via interactions between lipids and the membrane receptor of the protein.


Asunto(s)
Membrana Celular/metabolismo , Metabolismo de los Lípidos , Toxina Shiga/metabolismo , Esfingolípidos/metabolismo , Trihexosilceramidas/metabolismo , Animales , Transporte Biológico , Membrana Celular/química , Humanos , Unión Proteica , Toxina Shiga/química , Esfingolípidos/química , Trihexosilceramidas/química , Liposomas Unilamelares/química , Liposomas Unilamelares/metabolismo
8.
Commun Biol ; 5(1): 1131, 2022 10 26.
Artículo en Inglés | MEDLINE | ID: mdl-36289443

RESUMEN

Voltage-clamp fluorometry (VCF) supplies information about the conformational changes of voltage-gated proteins. Changes in the fluorescence intensity of the dye attached to a part of the protein that undergoes a conformational rearrangement upon the alteration of the membrane potential by electrodes constitute the signal. The VCF signal is generated by quenching and dequenching of the fluorescence as the dye traverses various local environments. Here we studied the VCF signal generation, using the Hv1 voltage-gated proton channel as a tool, which shares a similar voltage-sensor structure with voltage-gated ion channels but lacks an ion-conducting pore. Using mutagenesis and lipids added to the extracellular solution we found that the signal is generated by the combined effects of lipids during movement of the dye relative to the plane of the membrane and by quenching amino acids. Our 3-state model recapitulates the VCF signals of the various mutants and is compatible with the accepted model of two major voltage-sensor movements.


Asunto(s)
Activación del Canal Iónico , Protones , Canales Iónicos/metabolismo , Fluorometría , Aminoácidos , Lípidos
9.
Nano Lett ; 9(8): 2807-12, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19007289

RESUMEN

We report the first successful application of an ordered bicontinuous gyroid semiconducting network in a hybrid bulk heterojunction solar cell. The freestanding gyroid network is fabricated by electrochemical deposition into the 10 nm wide voided channels of a self-assembled, selectively degradable block copolymer film. The highly ordered pore structure is ideal for uniform infiltration of an organic hole transporting material, and solid-state dye-sensitized solar cells only 400 nm thick exhibit up to 1.7% power conversion efficiency. This patterning technique can be readily extended to other promising heterojunction systems and is a major step toward realizing the full potential of self-assembly in the next generation of device technologies.


Asunto(s)
Suministros de Energía Eléctrica , Nanotecnología , Energía Solar , Microscopía Electrónica de Rastreo , Polímeros/química , Semiconductores
10.
Sci Rep ; 10(1): 14017, 2020 08 20.
Artículo en Inglés | MEDLINE | ID: mdl-32820238

RESUMEN

Discarding by fisheries is one of the most wasteful human marine activities, yet we have few estimates of its scale. Reliable estimates of global discards are essential for sustainable fisheries management. Using United Nations Food and Agriculture Organization databases on country-specific landings, we estimated the discard rate and magnitude for global marine and estuarine capture fisheries using fishery-specific discard rates derived from direct observations and global gear-specific discard rates estimated within a Bayesian modelling framework. An estimated 9.1 million tonnes are discarded annually (95% uncertainty interval: 7-16 M t)-or 10.8% of the global catch (95% UI: 10-12%). Encouragingly, this is about half of the annual global discard rate estimated in the late 1980s. Trawl fisheries, especially demersal otter trawls, warrant intensified efforts to reduce discards. Periodic benchmarks of global discards are needed to assess the performance of reduction efforts.

11.
Biophys J ; 95(2): 669-81, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18390624

RESUMEN

We used wide angle x-ray scattering (WAXS) from stacks of oriented lipid bilayers to measure chain orientational order parameters and lipid areas in model membranes consisting of mixtures of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/cholesterol and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/cholesterol in fluid phases. The addition of 40% cholesterol to either DOPC or DPPC changes the WAXS pattern due to an increase in acyl chain orientational order, which is one of the main properties distinguishing the cholesterol-rich liquid-ordered (Lo) phase from the liquid-disordered (Ld) phase. In contrast, powder x-ray data from multilamellar vesicles does not yield information about orientational order, and the scattering from the Lo and Ld phases looks similar. An analytical model to describe the relationship between the chain orientational distribution and WAXS data was used to obtain an average orientational order parameter, S(x-ray). When 40% cholesterol is added to either DOPC or DPPC, S(x-ray) more than doubles, consistent with previous NMR order parameter measurements. By combining information about the average chain orientation with the chain-chain correlation spacing, we extended a commonly used method for calculating areas for gel-phase lipids to fluid-phase lipids and obtained agreement to within 5% of literature values.


Asunto(s)
Colesterol/química , Membrana Dobles de Lípidos/química , Fluidez de la Membrana , Modelos Químicos , Modelos Moleculares , Fosfolípidos/química , Simulación por Computador , Conformación Molecular , Transición de Fase , Difracción de Rayos X
12.
Biophys J ; 95(2): 682-90, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18390623

RESUMEN

Wide angle x-ray scattering (WAXS) from oriented lipid multilayers is used to examine liquid-ordered (Lo)/liquid-disordered (Ld) phase coexistence in the system 1,2-dioleoyl-sn-glycero-3-phosphocholine/1,2-dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol (DOPC/DPPC/Chol), which is a model for the outer leaflet of the animal cell plasma membrane. Using the method of analysis developed in the accompanying work, we find that two orientational distributions are necessary to fit the WAXS data at lower temperatures, whereas only one distribution is needed at temperatures higher than the miscibility transition temperature, T(mix) = 25-35 degrees C (for 1:1 DOPC/DPPC with 15%, 20%, 25%, and 30% Chol). We propose that the necessity for two distributions is a criterion for coexistence of Lo domains with a high S(x-ray) order parameter and Ld domains with a lower order parameter. This criterion is capable of detecting coexistence of small domains or rafts that the conventional x-ray criterion of two lamellar D spacings may not. Our T(mix) values tend to be slightly larger than published NMR results and microscopy results when the fluorescence probe artifact is considered. This is consistent with the sensitivity of WAXS to very short time and length scales, which makes it more capable of detecting small, short-lived domains that are likely close to T(mix).


Asunto(s)
Colesterol/química , Membrana Dobles de Lípidos/química , Microdominios de Membrana/química , Fosfolípidos/química , Conformación Molecular , Soluciones , Difracción de Rayos X
13.
J Am Chem Soc ; 130(51): 17334-41, 2008 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-19090750

RESUMEN

The solution structures of four enolates derived from beta-amino esters are investigated using (6)Li NMR spectroscopy in conjunction with the method of continuous variation (method of Job). Ensembles of homo- and heteroaggregated enolates are generated by mixing enantiomers of a single enolate (R/S mixtures), opposite antipodes of two different enolates (R/S' mixtures), and the same antipodes of two different enolates (R/R' mixtures). The numbers of observable aggregates and their dependence on the mole fraction of the two enolates confirm the hexamer assignments. Inherent symmetries observable in the (6)Li NMR spectra show the stereochemistry of chelation about the hexagonal drum.


Asunto(s)
Química Orgánica/métodos , Ésteres/química , Diseño de Fármacos , Litio/química , Espectroscopía de Resonancia Magnética , Modelos Químicos , Modelos Moleculares , Modelos Estadísticos , Programas Informáticos , Estereoisomerismo
14.
J Am Chem Soc ; 130(14): 4859-68, 2008 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-18336025

RESUMEN

The method of continuous variation in conjunction with 6Li NMR spectroscopy was used to characterize lithium enolates derived from 1-indanone, cyclohexanone, and cyclopentanone in solution. The strategy relies on forming ensembles of homo- and heteroaggregated enolates. The enolates form exclusively chelated dimers in N,N,N',N'-tetramethylethylenediamine and cubic tetramers in tetrahydrofuran and 1,2-dimethoxyethane.


Asunto(s)
Cetonas/química , Compuestos de Litio/química , Compuestos Organometálicos/química , Ciclohexanonas/química , Ciclopentanos/química , Indanos/química , Espectroscopía de Resonancia Magnética
15.
Diabetes Care ; 20(5): 753-6, 1997 May.
Artículo en Inglés | MEDLINE | ID: mdl-9135937

RESUMEN

OBJECTIVE: To improve understanding of the etiology of IDDM by analyzing spatial and space-time distribution of the incidence in children. RESEARCH DESIGN AND METHODS: Statistical tests to detect clustering were applied to a population-based register of 1,490 children (aged 0-16 years) with IDDM in Yorkshire, northern England. The Knox test analyzed clustering in space and time, and the Potthoff-Whittinghill test quantified spatial differences in incidence between small-area census units (electoral wards). The Potthoff-Whittinghill test was conditioned for childhood population density and deprivation (Townsend index). RESULTS: Both tests demonstrated clustering of IDDM in Yorkshire children. Space-time and spatial clustering is strongest in the younger children (0-4 and 5-9 years of age), even after conditioning for known associations. Clustering was more common in the county of Humberside during the years 1982-1985 and in wards of low population density (< 0.26 0- to 16 year-old subjects per hectare). CONCLUSIONS: The study revealed a nonrandom space-time distribution of IDDM in children not accounted for by known covarying demographic factors. The Potthoff-Whittinghill test has not previously been applied to childhood IDDM. The new finding of strong clustering in young children is consistent with early exposure, possibly in utero, to infectious agents or localized environmental sources.


Asunto(s)
Diabetes Mellitus Tipo 1/epidemiología , Adolescente , Factores de Edad , Niño , Preescolar , Análisis por Conglomerados , Demografía , Inglaterra/epidemiología , Femenino , Humanos , Incidencia , Lactante , Masculino , Modelos Teóricos , Densidad de Población , Sistema de Registros , Factores Sexuales
16.
J Vis Exp ; (95): 52281, 2015 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-25650630

RESUMEN

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. However, commonly used protocols to grow GUVs must be modified in order to form GUVs containing functional transmembrane proteins. This article describes two dehydration-rehydration methods - electroformation and gel-assisted swelling - to form GUVs containing the voltage-gated potassium channel, KvAP. In both methods, a solution of protein-containing small unilamellar vesicles is partially dehydrated to form a stack of membranes, which is then allowed to swell in a rehydration buffer. For the electroformation method, the film is deposited on platinum electrodes so that an AC field can be applied during film rehydration. In contrast, the gel-assisted swelling method uses an agarose gel substrate to enhance film rehydration. Both methods can produce GUVs in low (e.g., 5 mM) and physiological (e.g., 100 mM) salt concentrations. The resulting GUVs are characterized via fluorescence microscopy, and the function of reconstituted channels measured using the inside-out patch-clamp configuration. While swelling in the presence of an alternating electric field (electroformation) gives a high yield of defect-free GUVs, the gel-assisted swelling method produces a more homogeneous protein distribution and requires no special equipment.


Asunto(s)
Canales de Potasio con Entrada de Voltaje/química , Liposomas Unilamelares/química , Microscopía Fluorescente/métodos , Técnicas de Placa-Clamp/métodos , Canales de Potasio con Entrada de Voltaje/metabolismo , Liposomas Unilamelares/metabolismo
17.
Nat Neurosci ; 18(11): 1577-83, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26389841

RESUMEN

The selectivity of ion channels is fundamental for their roles in electrical and chemical signaling and in ion homeostasis. Although most ion channels exhibit stable ion selectivity, the prevailing view of purinergic P2X receptor channels, transient receptor potential V1 (TRPV1) channels and acid-sensing ion channels (ASICs) is that their ion conduction pores dilate upon prolonged activation. We investigated this mechanism in P2X receptors and found that the hallmark shift in equilibrium potential observed with prolonged channel activation does not result from pore dilation, but from time-dependent alterations in the concentration of intracellular ions. We derived a physical model to calculate ion concentration changes during patch-clamp recordings, which validated our experimental findings and provides a quantitative guideline for effectively controlling ion concentration. Our results have fundamental implications for understanding ion permeation and gating in P2X receptor channels, as well as more broadly for using patch-clamp techniques to study ion channels and neuronal excitability.


Asunto(s)
Adenosina Trifosfato/farmacología , Activación del Canal Iónico/efectos de los fármacos , Potenciales de la Membrana/efectos de los fármacos , Receptores Purinérgicos P2X/metabolismo , Línea Celular , Humanos , Activación del Canal Iónico/fisiología , Técnicas de Placa-Clamp/métodos , Canales de Potencial de Receptor Transitorio/fisiología
18.
Eur J Cancer ; 35(1): 91-6, 1999 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-10211094

RESUMEN

Age-related differences in the incidence and immunological subtypes of acute lymphoblastic leukaemia (ALL) suggest that it may be composed of more than one disease entity, each with different aetiologies. Childhood leukaemia (of which the majority of cases are ALL) has been suspected of having an infectious aetiology, but few studies have systematically examined ALL for clustering by age group. The aim of this study was to examine ALL for evidence of space-time clustering of date and place of diagnosis by age group. Knox space-time analysis was carried out separately for three different age groups: childhood (0-14 years), young adult (15-34 years) and older adults (35-79 years). Data on 968 cases of ALL aged 0-79 years, arising during 1984-1993 in the areas covered by a specialist population based register of leukaemias and lymphomas in parts of the U.K., were used in the analysis. Space-time clustering of diagnoses was limited to children aged 0-14 years. It was more prominent in those diagnosed in the period 1984-1988, than in those diagnosed in 1989-1993. The clustering may indicate an infectious aetiology for childhood ALL, or could be the result of episodic exposures to some environmental hazard.


Asunto(s)
Leucemia-Linfoma Linfoblástico de Células Precursoras/epidemiología , Adolescente , Adulto , Distribución por Edad , Anciano , Niño , Preescolar , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Características de la Residencia , Agrupamiento Espacio-Temporal , Reino Unido/epidemiología
19.
Leuk Lymphoma ; 36(1-2): 85-100, 1999 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-10613453

RESUMEN

The object of this study was to examine cases of Hodgkin's Disease (HD) for evidence of space-time clustering of onsets by age group, sex and disease subtype. Data comprised 2024 cases of HD aged 0-79 years arising throughout the period 1984 to 1993 in the areas covered by a specialist population based register of leukaemias and lymphomas. Knox space-time analysis was used separately for 3 different age groups: childhood (0-14 years), young adult (15-34 years) and older adults (35-79 years); for adult cases separate analysis was carried out by sex and for the nodular and non-nodular sclerosing subtypes. Results showed that space-time clustering of onsets was limited to the nodular sclerosing cases. It was more prominent in young adult nodular sclerosing cases aged 15-34 years (particularly females) diagnosed in the period 1984-88, than in those diagnosed in 1989-93. We conclude that clustering may provide further evidence that an infectious process is involved in the aetiology of young adult nodular sclerosing cases of HD.


Asunto(s)
Enfermedad de Hodgkin/epidemiología , Adolescente , Adulto , Factores de Edad , Anciano , Niño , Preescolar , Análisis por Conglomerados , Humanos , Lactante , Recién Nacido , Persona de Mediana Edad , Factores Sexuales , Factores de Tiempo , Reino Unido/epidemiología
20.
J Epidemiol Community Health ; 46(6): 566-72, 1992 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1494069

RESUMEN

STUDY OBJECTIVE: The aim was to test a large set of childhood leukaemia and lymphoma registrations for the presence of clusters in space and in time. DESIGN: The study was a space-time cluster analysis. SETTING: England, Wales and Scotland. PATIENTS: All registrations for leukaemia and lymphoma between 1966 and 1983 in children aged 0 to 14 years were examined. The records included date and age of registration, sex, diagnosis, and the map reference of the postcode of residence. Of the 9411 registrations, 8888 were suitable for inclusion. MAIN RESULTS: There was a statistically significant excess of case pairs occurring jointly within 0.5 km and 60 d of each other: 68 pairs compared with 50.0 expected. The excess was detectable in central England, in the north of England and Scotland, but not in the south west of England. It was concentrated within the age band 4 to 7 years and among the lymphatic leukaemias. Several potential artefacts were considered and excluded, but the possibility remained that clustered detections might be triggered by haematological examinations undertaken for some communicable disease. CONCLUSIONS: There was strong evidence of joint spatial-temporal clustering, with an excess of pairs separated by very short time and distance intervals. The causes are probably biological rather than artefactual, but further work will be necessary in order to exclude the latter.


Asunto(s)
Leucemia/epidemiología , Linfoma no Hodgkin/epidemiología , Adolescente , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Prevalencia , Sistema de Registros , Características de la Residencia , Agrupamiento Espacio-Temporal , Factores de Tiempo , Reino Unido/epidemiología
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