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1.
Mar Pollut Bull ; 178: 113500, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35427814

RESUMEN

Marine debris, directly and indirectly, threatens marine habitat and biota. Fishing activity is generally recognised as a contributor to marine debris, but the relative input from recreational fishing remains unassessed. Here we provide the first comprehensive literature review of recreational fishing marine debris (RFMD) on a global scale. A systematic literature review identified 70 studies related to RFMD, and plastic and metal respectively were the dominant debris materials found. Nearshore coastal areas and reefs, acted as both sources and sinks of RFMD and a diverse suite of potential impacts such as ghost fishing and entanglement were identified at local scales. Overall, research of RFMD is lacking globally, however, its role in marine debris input is likely underestimated. We recommend more research on the volumes and risks, using a standardised classification approach. Where intervention is required, we suggest cooperative approaches between the sector and authorities.


Asunto(s)
Caza , Residuos , Ecosistema , Monitoreo del Ambiente , Plásticos , Residuos/análisis
2.
Herit Sci ; 6(1): 58, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-31258911

RESUMEN

This paper demonstrates the combined use of X-ray computed tomography (XCT), energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) to evaluate the conservational history of the dentary (lower jaw) of Megalosaurus bucklandii Mantell, 1827, the first scientifically described dinosaur. Previous analysis using XCT revealed that the specimen had undergone at least two phases of repair using two different kinds of plaster, although their composition remained undetermined. Additional chemical analysis using EDX and XRF has allowed the determination of the composition of these unidentified plasters, revealing that they are of similar composition, composed dominantly of 'plaster of Paris' mixed with quartz sand and calcite, potentially from the matrix material of the Stonesfield Slate, with the trace presence of chlorine. One of the plasters unusually contains the pigment minium (naturally occurring lead tetroxide; Pb2 2+Pb4+O4) whilst the other seems to have an additional coating of barium hydroxide (Ba(OH)2), indicating that these likely represent two separate stages of repair. The potential of this combined approach for evaluating problematic museum objects for conservation is further discussed as is its usage in cultural heritage today.

4.
Curr Med Res Opin ; 31(11): 1985-91, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26296234

RESUMEN

BACKGROUND: Health and life expectancy for people with hemophilia have improved significantly in recent years, but we face new challenges, especially in the context of resource-constrained health services. AIM: This paper aims to highlight such challenges and propose practical solutions. METHODS: Nine hemophilia specialists from Australia and New Zealand reached consensus on areas of greatest need for improvement in hemophilia care in these countries, based on clinical experience and published data, and agreed on how to address these. RESULTS: Demography, optimizing treatment and assessing treatment success were identified as broad areas of challenge which included: comorbidities in ageing patients; transitioning from pediatric to adult care; equity of care for remote populations; weight-based dosing in obese patients; tailoring prophylaxis; accurate diagnosis of acute joint pain; managing chronic arthropathy; providing psychosocial support; consistency in definitions and assessment; and quantifiable outcome measures. Practice points included increased cross-specialty coordination and including psychologists and rheumatologists as part of comprehensive care teams; close collaboration between pediatric and adult centers to facilitate transition of care; systems such as telehealth that ensure continuity of care for remote populations; using pharmacokinetic data to tailor therapy; rapid and accurate diagnosis of acute joint pain; using data from bleeding registries to assess treatment effects and help with service planning; and ensuring consistency through benchmarking and standardization of HTCs. SUMMARY: Achieving treatment equity, optimal outcomes and cost savings may be possible through investing in national governance structures, expanding the comprehensive model of care and implementing innovative solutions tailored to local needs.


Asunto(s)
Hemofilia A/terapia , Transición a la Atención de Adultos , Adulto , Australia , Niño , Consenso , Humanos , Nueva Zelanda , Pediatría
5.
AJNR Am J Neuroradiol ; 36(9): 1589-98, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26185325

RESUMEN

BACKGROUND AND PURPOSE: Gadobenate dimeglumine (MultiHance) has higher r1 relaxivity than gadoterate meglumine (Dotarem) which may permit the use of lower doses for MR imaging applications. Our aim was to compare 0.1- and 0.05-mmol/kg body weight gadobenate with 0.1-mmol/kg body weight gadoterate for MR imaging assessment of brain tumors. MATERIALS AND METHODS: We performed crossover, intraindividual comparison of 0.1-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 1) and 0.05-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 2). Adult patients with suspected or known brain tumors were randomized to Arm 1 (70 patients) or Arm 2 (107 patients) and underwent 2 identical examinations at 1.5 T. The agents were injected in randomized-sequence order, and the 2 examinations were separated by 2-14 days. MR imaging scanners, imaging sequences (T1-weighted spin-echo and T1-weighted high-resolution gradient-echo), and acquisition timing were identical for the 2 examinations. Three blinded readers evaluated images for diagnostic information (degree of definition of lesion extent, lesion border delineation, visualization of lesion internal morphology, contrast enhancement) and quantitatively for percentage lesion enhancement and lesion-to-background ratio. Safety assessments were performed. RESULTS: In Arm 1, a highly significant superiority (P < .002) of 0.1-mmol/kg gadobenate was demonstrated by all readers for all end points. In Arm 2, no significant differences (P > .1) were observed for any reader and any end point, with the exception of percentage enhancement for reader 2 (P < .05) in favor of 0.05-mmol/kg gadobenate. Study agent-related adverse events were reported by 2/169 (1.2%) patients after gadobenate and by 5/175 (2.9%) patients after gadoterate. CONCLUSIONS: Significantly superior morphologic information and contrast enhancement are demonstrated on brain MR imaging with 0.1-mmol/kg gadobenate compared with 0.1-mmol/kg gadoterate. No meaningful differences were recorded between 0.05-mmol/kg gadobenate and 0.1-mmol/kg gadoterate.


Asunto(s)
Neoplasias Encefálicas/patología , Imagen por Resonancia Magnética/métodos , Adulto , Anciano , Medios de Contraste , Estudios Cruzados , Femenino , Humanos , Masculino , Meglumina/análogos & derivados , Persona de Mediana Edad , Compuestos Organometálicos
6.
AJNR Am J Neuroradiol ; 36(1): 14-23, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25300984

RESUMEN

BACKGROUND AND PURPOSE: Gadobutrol (Gadavist) and gadoteridol (ProHance) have similar macrocyclic molecular structures, but gadobutrol is formulated at a 2-fold higher (1 mol/L versus 0.5 mol/L) concentration. We sought to determine whether this difference impacts morphologic contrast-enhanced MR imaging. MATERIALS AND METHODS: Two hundred twenty-nine adult patients with suspected or known brain tumors underwent two 1.5T MR imaging examinations with gadoteridol or gadobutrol administered in randomized order at a dose of 0.1 mmol/kg of body weight. Imaging sequences and T1 postinjection timing were identical for both examinations. Three blinded readers evaluated images qualitatively and quantitatively for lesion detection and for accuracy in characterization of histologically confirmed brain tumors. Data were analyzed by using the Wilcoxon signed rank test, the McNemar test, and a mixed model. RESULTS: Two hundred nine patients successfully completed both examinations. No reader noted a significant qualitative or quantitative difference in lesion enhancement, extent, delineation, or internal morphology (P values = .69-1.00). One hundred thirty-nine patients had at least 1 histologically confirmed brain lesion. Two readers found no difference in the detection of patients with lesions (133/139 versus 135/139, P = .317; 137/139 versus 136/139, P = .564), while 1 reader found minimal differences in favor of gadoteridol (136/139 versus 132/139, P = .046). Similar findings were noted for the number of lesions detected and characterization of tumors (malignant/benign). Three-reader agreement for characterization was similar for gadobutrol (66.4% [κ = 0.43]) versus gadoteridol (70.3% [κ = 0.45]). There were no significant differences in the incidence of adverse events (P = .199). CONCLUSIONS: Gadoteridol and gadobutrol at 0.1 mmol/kg of body weight provide similar information for visualization and diagnosis of brain lesions. The 2-fold higher gadolinium concentration of gadobutrol provides no benefit for routine morphologic imaging.


Asunto(s)
Neoplasias Encefálicas/diagnóstico , Medios de Contraste/administración & dosificación , Compuestos Heterocíclicos/administración & dosificación , Imagen por Resonancia Magnética/métodos , Compuestos Organometálicos/administración & dosificación , Adulto , Anciano , Estudios Cruzados , Femenino , Gadolinio/administración & dosificación , Humanos , Masculino , Persona de Mediana Edad , Neuroimagen/métodos
7.
J Thromb Haemost ; 12(6): 987-98, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24655807

RESUMEN

BACKGROUND: Pannexin-1 (Panx1) forms an anion-selective channel with a permeability up to ~1 kDa and represents a non-lytic, non-vesicular ATP release pathway in erythrocytes, leukocytes and neurons. Related connexin gap junction proteins have been reported in platelets; however, the expression and function of the pannexins remain unknown. OBJECTIVE: To determine the expression and function of pannexins in human plate-lets, using molecular, cellular and functional techniques. METHODS: Panx1 expression in human platelets was det-ermined using qPCR and antibody-based techniques. Contributions of Panx1 to agonist-evoked efflux of cytoplasmic calcein, Ca(2+) influx, ATP release and aggregation were assessed in washed platelets under conditions where the P2X1 receptor response was preserved (0.32 U mL(-1) apyrase). Thrombus formation in whole blood was assessed in vitro using a shear chamber assay. Two structurally unrelated and widely used Panx1 inhibitors, probenecid and carbenoxolone, were used throughout this study, at concentrations that do not affect connexin channels. RESULTS: PANX1, but not PANX2 or PANX3, mRNA was detected in human platelets. Furthermore, Panx1 protein is glycosylated and present on the plasma membrane of platelets, and displays weak physical association with P2X1 receptors. Panx1 inhibition blocked thrombin-evoked efflux of calcein, and reduced Ca(2+) influx, ATP release, platelet aggregation and thrombus formation under arterial shear rates in vitro. The Panx1-dependent contribution was not additive to that of P2X1 receptors. CONCLUSIONS: Panx1 is expressed on human platelets and amplifies Ca(2+) influx, ATP release and aggregation through the secondary activation of P2X1 receptors. We propose that Panx1 represents a novel target for the management of arterial thrombosis.


Asunto(s)
Plaquetas/metabolismo , Membrana Celular/metabolismo , Conexinas/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Activación Plaquetaria , Adenosina Trifosfato/metabolismo , Plaquetas/efectos de los fármacos , Señalización del Calcio , Carbenoxolona/farmacología , Membrana Celular/efectos de los fármacos , Conexinas/antagonistas & inhibidores , Conexinas/genética , Fluoresceínas/metabolismo , Células HEK293 , Humanos , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Proteínas del Tejido Nervioso/genética , Activación Plaquetaria/efectos de los fármacos , Agregación Plaquetaria , Probenecid/farmacología , ARN Mensajero/metabolismo , Receptores Purinérgicos P2X1/metabolismo , Trombina/farmacología , Factores de Tiempo , Transfección
8.
QJM ; 106(1): 27-33, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23019590

RESUMEN

AIM: The aim of our study was to assess the impact of 8-weekly intravenous (IV) antibiotics on exacerbation frequency and health-related quality of life in bronchiectasis. METHODS: Patients were recruited prospectively from June 2008 to December 2010. Patients with recurrent exacerbations (five or more exacerbations per year) and subjectively reporting ill health between antibiotic courses were recruited. Eight-weekly IV antibiotics (for 14 days) were initiated. Patients were followed up for 1 year. Main outcome was reduction in exacerbation frequency and improvement in health-related quality of life (HRQoL) at 1 year after starting intravenous antibiotic therapy. Other outcomes recorded were forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), incremental shuttle walk test (ISWT), 24-h sputum volume, sputum microbiology, body mass index (BMI), markers of inflammation--white cell count (WCC), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). RESULTS: In total, 19 patients were recruited. Mean age was 64.1 years and 52.6% were female. With 8-weekly antibiotics, there was a significant reduction in the number of exacerbations [mean (SE): 9.3 (0.5) in the year before vs. 8.0 (0.4) in the year after; P = 0.02]. In 63.2%, Leicester Cough Questionnaire (LCQ) improved by ≥1.3 U (P = 0.006)] and in 42.1% St. George's Respiratory Questionnaire (SGRQ) improved by ≥4 U (P = 0.03). Exercise capacity increased by 58.7 m (P = 0.004). There was no improvement in the other end points. CONCLUSION: Treatment with 8-weekly intravenous antibiotics in severe bronchiectasis reduced exacerbation frequency and improved exercise tolerance and health-related quality of life.


Asunto(s)
Antibacterianos/administración & dosificación , Bronquiectasia/tratamiento farmacológico , Administración Oral , Anciano , Antibacterianos/uso terapéutico , Bacterias/aislamiento & purificación , Bronquiectasia/fisiopatología , Bronquiectasia/rehabilitación , Comorbilidad , Esquema de Medicación , Tolerancia al Ejercicio/efectos de los fármacos , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Calidad de Vida , Prevención Secundaria , Índice de Severidad de la Enfermedad , Esputo/microbiología , Resultado del Tratamiento
9.
J Thromb Haemost ; 10(9): 1722-32, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22741535

RESUMEN

Ion channels are transmembrane proteins that play ubiquitous roles in cellular homeostasis and activation. In addition to their recognized role in the regulation of ionic permeability and thus membrane potential, some channel proteins possess intrinsic kinase activity, directly interact with integrins or are permeable to molecules up to ≈1000 Da. The small size and anuclear nature of the platelet has often hindered progress in understanding the role of specific ion channels in hemostasis, thrombosis and other platelet-dependent events. However, with the aid of transgenic mice and 'surrogate' patch clamp recordings from primary megakaryocytes, important unique contributions to platelet function have been identified for several classes of ion channel. Examples include ATP-gated P2X1 channels, Orai1 store-operated Ca2+ channels, voltage-gated Kv1.3 channels, AMPA and kainate glutamate receptors and connexin gap junction channels. Furthermore, evidence exists that some ion channels, such as NMDA glutamate receptors, contribute to megakaryocyte development. This review examines the evidence for expression of a range of ion channels in the platelet and its progenitor cell, and highlights the distinct roles that these proteins may play in health and disease.


Asunto(s)
Plaquetas/citología , Canales Iónicos/fisiología , Megacariocitos/citología , Animales , Humanos , Activación del Canal Iónico/fisiología , Ratones , Neurotransmisores/fisiología
10.
J R Coll Physicians Edinb ; 41(2): 132-9; quiz 139, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21677919

RESUMEN

Bronchiectasis is a chronic debilitating condition. Pathologically, a vicious cycle of infection and inflammation exists in the permanently damaged airways with patients suffering a persistent cough, chronic daily sputum production and recurrent chest infections. Once termed an 'orphan disease', the prevalence of bronchiectasis has become increasingly recognised over the past few decades. The associated burden of disease in terms of respiratory morbidity, effect on patients' health-related quality of life and the economic cost of long term management is significant and it has become apparent that more research into its causes and management is urgently needed. This article reviews what is currently known about bronchiectasis, its pathophysiology, aetiology and management strategies.


Asunto(s)
Bronquiectasia/epidemiología , Bronquiectasia/terapia , Bronquios/patología , Bronquios/fisiopatología , Bronquiectasia/diagnóstico , Bronquiectasia/fisiopatología , Países en Desarrollo , Humanos , Factores Socioeconómicos
11.
Clin Anat ; 24(6): 741-7, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21400610

RESUMEN

The human costotransverse joint (CTJ) is the articulation between the posterior tubercle of the ribs with the first through tenth costal facet of the thoracic transverse processes. While the CTJ is well defined anatomically and considered a synovial joint, the human CTJ as a pain generating structure is controversial and not supported from a histological perspective. The objective of the present study was to investigate the histological pain producing properties of CTJ capsule tissue. Ten micron cross-sections at each level (1-10) were stained with H & E or immunostained with antisera against Substance P (SP), calcitonin-gene-related peptide (CGRP), and neuropeptide Y (NPY). Immunoreactivity was confirmed for SP, CGRP, and NPY within the CTJ tissue samples of two unembalmed male cadavers. The presence of previously mentioned neuropeptides suggests that human CTJ is capable of producing pain through somatic and autonomic nervous systems. Therefore, clinicians should consider the CTJ as a differential diagnostic possibility when examining and treating painful thoracic conditions.


Asunto(s)
Cápsula Articular/anatomía & histología , Costillas/anatomía & histología , Vértebras Torácicas/anatomía & histología , Humanos , Inmunohistoquímica , Masculino
12.
Acta Paediatr ; 99(7): 1104-7, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20151952

RESUMEN

UNLABELLED: A case of extensive deep venous thrombosis in a four a day old infant was presented. Unusually this patient was shown to be heterozygous for three thrombophilia genes; Factor V Leiden, prothrombin and antithrombin gene mutations, the latter being novel. CONCLUSION: There are no randomized controlled trials to guide management in deep venous thrombosis in the newborn but knowledge of the prothrombotic risk factors may help direct treatment.


Asunto(s)
Protrombina/genética , Venas Renales/diagnóstico por imagen , Trombosis de la Vena/diagnóstico , Humanos , Recién Nacido , Mutación , Factores de Riesgo , Ultrasonografía , Trombosis de la Vena/genética
13.
J Thromb Haemost ; 8(4): 783-9, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20102489

RESUMEN

BACKGROUND: Preimplantation genetic diagnosis (PGD) is an appealing option for couples at risk of having a child with hemophilia A (HA). Although many clinics offer PGD for HA by gender selection, an approach that detects the presence of the underlying F8 mutation has several advantages. OBJECTIVES: To develop and validate analysis protocols combining indirect and direct methods for identifying F8 mutations in single cells, and to apply these protocols clinically for PGD. METHODS: A panel of microsatellite markers in linkage disequilibrium with F8 were validated for single-cell multiplex polymerase chain reaction. For point mutations, a primer extension genotyping assay was included in the multiplex. Amplification efficiency was evaluated using buccal cells and blastomeres. Four clinical PGD analyses were performed, for two families. RESULTS: Across all validation experiments and the clinical PGD cases, approximately 80% of cells were successfully genotyped. Following one of the PGD cycles, healthy twins were born to a woman who carries the F8 intron 22 inversion. The PGD analysis for the other family was complicated by possible germline mosaicism associated with a de novo F8 mutation, and no pregnancy was achieved. CONCLUSIONS: PGD for the F8 intron 22 inversion using microsatellite linkage analysis was validated by the birth of healthy twins to one of the couples. The other family's situation highlighted the complexities associated with de novo mutations, and possible germline mosaicism. As many cases of HA result from de novo mutations, these factors must be considered when assessing the reproductive options for such families.


Asunto(s)
Factor VIII/genética , Pruebas Genéticas , Hemofilia A/diagnóstico , Hemofilia A/genética , Desequilibrio de Ligamiento , Diagnóstico Preimplantación/métodos , Transferencia de Embrión , Femenino , Fertilización In Vitro , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Intrones , Nacimiento Vivo , Masculino , Repeticiones de Microsatélite , Mosaicismo , Linaje , Fenotipo , Mutación Puntual , Reacción en Cadena de la Polimerasa , Valor Predictivo de las Pruebas , Embarazo , Reproducibilidad de los Resultados , Gemelos
16.
Br J Pharmacol ; 154(4): 882-9, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18414379

RESUMEN

BACKGROUND AND PURPOSE: Emerging evidence suggests that activation of G-protein-coupled receptors (GPCRs) can be directly regulated by membrane voltage. However, the physiological and pharmacological relevance of this effect remains unclear. We have further examined this phenomenon for P2Y1 receptors in the non-excitable megakaryocyte using a range of agonists and antagonists. EXPERIMENTAL APPROACH: Simultaneous whole-cell patch clamp and fura-2 fluorescence recordings of rat megakaryocytes, which lack voltage-gated Ca2+ influx, were used to examine the voltage-dependence of P2Y1 receptor-evoked IP3-dependent Ca2+ mobilization. RESULTS: Depolarization transiently and repeatedly enhanced P2Y1 receptor-evoked Ca2+ mobilization across a wide concentration range of both weak, partial and full, potent agonists. Moreover, the amplitude of the depolarization-evoked [Ca2+]i increase displayed an inverse relationship with agonist concentration, such that the greatest potentiating effect of voltage was observed at near-threshold levels of agonist. Unexpectedly, depolarization also stimulated an [Ca2+]i increase in the absence of agonist during exposure to the competitive antagonists A3P5PS and MRS2179, or the allosteric enhancer 2,2'-pyridylisatogen tosylate. A further effect of some antagonists, particularly suramin, was to enhance the depolarization-evoked Ca2+ responses during co-application of an agonist. Of several P2Y1 receptor inhibitors, only SCH202676, which has a proposed allosteric mechanism of action, could block ADP-induced voltage-dependent Ca2+ release. CONCLUSIONS AND IMPLICATIONS: The ability of depolarization to potentiate GPCRs at near-threshold agonist concentrations represents a novel mechanism for coincidence detection. Furthermore, the induction and enhancement of voltage-dependent GPCR responses by antagonists has implications for the design of therapeutic compounds.


Asunto(s)
Canales de Calcio/metabolismo , Megacariocitos/metabolismo , Receptores Purinérgicos P2/metabolismo , Adenosina Difosfato/metabolismo , Regulación Alostérica , Animales , Canales de Calcio/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Colorantes Fluorescentes , Fura-2 , Masculino , Técnicas de Placa-Clamp , Agonistas del Receptor Purinérgico P2 , Antagonistas del Receptor Purinérgico P2 , Ratas , Ratas Wistar , Receptores Purinérgicos P2Y1 , Transducción de Señal
17.
Haemophilia ; 13(4): 420-7, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17610560

RESUMEN

The genetic basis of haemophilia A (HA) is well-established, and many haematology services are supported by molecular biology laboratories that offer factor VIII genetic testing for HA patients. This report describes the results from factor VIII gene (F8) analysis of a New Zealand cohort of 45 proband HA patients. We screened all proband HA patients attending local clinics to determine the molecular basis of disease in each case. We also aimed to evaluate the significance of founder effect in this population and to explain an unusual case of HA in a female patient. HA patients were screened for the common F8 gene inversion mutations using previously described PCR-based techniques, and for single base substitution mutations using denaturing high performance liquid chromatography and DNA sequencing. Analysis of microsatellite markers located within or near F8 was used to determine identity by descent and trace inheritance patterns of disease alleles. X-chromosome inactivation (XCI) patterns were detected using methylation specific PCR. Pathogenic F8 gene mutations were detected in all 45 HA patients in this cohort and non-random XCI was confirmed in a female haemophiliac. We report nine novel F8 mutations, including two splicing mutations, a five nucleotide deletion and a large deletion at the 5' end of the gene. The molecular aetiology of HA was similar to that described in other studies but the distribution of mutations was unusual due to founder effects, with almost a quarter of all probands being descended from just three individuals.


Asunto(s)
Factor VIII/genética , Efecto Fundador , Hemofilia A/genética , Inactivación del Cromosoma X/genética , Análisis Mutacional de ADN/métodos , Femenino , Haplotipos/genética , Hemofilia A/etiología , Humanos , Masculino , Nueva Zelanda , Linaje , Reacción en Cadena de la Polimerasa/métodos , Embarazo , Diagnóstico Prenatal
18.
J Thromb Haemost ; 5(5): 910-7, 2007 May.
Artículo en Inglés | MEDLINE | ID: mdl-17362227

RESUMEN

In the platelet, it is well established that many G-protein- and tyrosine kinase-coupled receptors stimulate phospholipase-C-dependent Ca(2+) mobilization; however, the extent to which secondary activation of adenosine 5'-triphosphate (ATP)-gated P2X(1) receptors contributes to intracellular Ca(2+) responses remains unclear. We now show that selective inhibition of P2X(1) receptors substantially reduces the [Ca(2+)](i) increase evoked by several important agonists in human platelets; for collagen, thromboxane A(2), thrombin, and adenosine 5'-diphoshate (ADP) the maximal effect was a reduction to 18%, 34%, 52%, and 69% of control, respectively. The direct contribution of P2X(1) to the secondary Ca(2+) response was far greater than that of either P2Y receptors activated by co-released ADP, or via synergistic P2X(1):P2Y interactions. The relative contribution of P2X(1) to the peak Ca(2+) increase varied with the strength of the initial stimulus, being greater at low compared to high levels of stimulation for both glycoprotein VI and PAR-1, whereas P2X(1) contributed equally at both low and high levels of stimulation of thromboxane A(2) receptors. In contrast, only strong stimulation of P2Y receptors resulted in significant P2X(1) receptor activation. ATP release was detected by soluble luciferin:luciferase in response to all agonists that stimulated secondary P2X(1) receptor activation. However, P2X(1) receptors were stimulated earlier and to a greater extent than predicted from the average ATP release, which can be accounted for by a predominantly autocrine mechanism of activation. Given the central role of [Ca(2+)](i) increases in platelet activation, these studies indicate that ATP should be considered alongside ADP and thromboxane A(2) as a significant secondary platelet agonist.


Asunto(s)
Plaquetas/efectos de los fármacos , Calcio/metabolismo , Agonistas del Receptor Purinérgico P2 , Adenosina Difosfato/farmacología , Bencenosulfonatos/farmacología , Plaquetas/citología , Plaquetas/metabolismo , Humanos , Luminiscencia , Receptores Purinérgicos P2X , Espectrometría de Fluorescencia , Tromboxano A2/farmacología
19.
Haemophilia ; 13(2): 124-30, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17286764

RESUMEN

ReFacto is a recombinant B-domain-deleted, monoclonal antibody-purified, solvent-detergent-treated factor VIII (BDDrFVIII) with no albumin added to the final formulation. Although ReFacto has been shown to be bioequivalent to a plasma-derived FVIII product (Hemophil-M) in a randomized, crossover pharmacokinetic (PK) study, the comparability of ReFacto with the full-length (complete sequence) recombinant FVIII (FLrFVIII, Advate) product has not been previously examined in this manner. The primary objective of this study was to compare the PKs of ReFacto with those of Advate in patients with severe haemophilia A. This was a third-party unblinded, randomized, multicentre, two-period crossover PKs study of ReFacto and Advate in subjects with severe haemophilia A (FVIII:C < or =1%). Blood samples were collected over a 48-h period after i.v. administration of each of the FVIII products. FVIII:C was determined using the chromogenic substrate assay (CSA) in a central laboratory. The plasma FVIII:C PK parameters of ReFacto and Advate were determined using non-compartmental analysis. Bioequivalence was assessed on maximum plasma concentration (C(max)) and the area under the plasma concentration vs. time curves (AUCs) using an anova. The two products were judged to be equivalent if the 90% confidence limits of the ratio of the geometric mean values of C(max) and AUCs fell within the interval of 80-125%. Results from this PKs comparison of two different rFVIII products, using chromogenic substrate assay to measure FVIII:C, showed that ReFacto and Advate are bioequivalent to each other.


Asunto(s)
Coagulantes/farmacocinética , Factor VIII/farmacocinética , Hemofilia A/tratamiento farmacológico , Adulto , Anciano , Área Bajo la Curva , Coagulantes/administración & dosificación , Estudios Cruzados , Ética en Investigación , Factor VII/administración & dosificación , Factor VII/farmacocinética , Factor VIII/administración & dosificación , Humanos , Masculino , Persona de Mediana Edad , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacocinética , Equivalencia Terapéutica
20.
Acta Physiol (Oxf) ; 189(1): 33-46, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17280555

RESUMEN

AIM: Hypokalaemia is associated with a lethal form of ventricular tachycardia (VT), torsade de pointes, through pathophysiological mechanisms requiring clarification. METHODS: Left ventricular endocardial and epicardial monophasic action potentials were compared in isolated mouse hearts paced from the right ventricular epicardium perfused with hypokalaemic (3 and 4 mm [K(+)](o)) solutions. Corresponding K(+) currents were compared in whole-cell patch-clamped epicardial and endocardial myocytes. RESULTS: Hypokalaemia prolonged epicardial action potential durations (APD) from mean APD(90)s of 37.2 +/- 1.7 ms (n = 7) to 58.4 +/- 4.1 ms (n =7) and 66.7 +/- 2.1 ms (n = 11) at 5.2, 4 and 3 mm [K(+)](o) respectively. Endocardial APD(90)s correspondingly increased from 51.6 +/- 1.9 ms (n = 7) to 62.8 +/- 2.8 ms (n = 7) and 62.9 +/- 5.9 ms (n = 11) giving reductions in endocardial-epicardial differences, DeltaAPD(90), from 14.4 +/- 2.6 to 4.4 +/- 5.0 and -3.4 +/- 6.0 ms respectively. Early afterdepolarizations (EADs) occurred in epicardia in three of seven spontaneously beating hearts at 4 mm [K(+)](o) with triggered beats followed by episodes of non-sustained VT in nine of 11 preparations at 3 mm. Programmed electrical stimulation never induced arrhythmic events in preparations perfused with normokalemic solutions yet induced VT in two of seven and nine of 11 preparations at 4 and 3 mm [K(+)](o) respectively. Early outward K(+) current correspondingly fell from 73.46 +/- 8.45 to 61.16+/-6.14 pA/pF in isolated epicardial but not endocardial myocytes (n = 9) (3 mm [K(+)](o)). CONCLUSIONS: Hypokalaemic mouse hearts recapitulate the clinical arrhythmogenic phenotype, demonstrating EADs and triggered beats that might initiate VT on the one hand and reduced transmural dispersion of repolarization reflected in DeltaAPD(90) suggesting arrhythmogenic substrate on the other.


Asunto(s)
Arritmias Cardíacas/fisiopatología , Hipopotasemia/fisiopatología , Disfunción Ventricular Izquierda/fisiopatología , Potenciales de Acción/fisiología , Animales , Bradicardia/fisiopatología , Estimulación Eléctrica , Endocardio/fisiopatología , Femenino , Hipopotasemia/complicaciones , Masculino , Ratones , Miocitos Cardíacos/fisiología , Técnicas de Placa-Clamp , Pericardio/fisiopatología , Potasio/fisiología , Factores de Riesgo , Taquicardia Ventricular/fisiopatología , Torsades de Pointes/etiología , Torsades de Pointes/fisiopatología
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