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1.
2.
Sci Rep ; 11(1): 21055, 2021 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-34702838

RESUMO

Aspergillus fumigatus is a fungal pathogen whose effects can be debilitating and potentially fatal in immunocompromised patients. Current drug treatment options for this infectious disease are limited to just a few choices (e.g. voriconazole and amphotericin B) and these themselves have limitations due to potentially adverse side effects. Furthermore, the likelihood of the development of resistance to these current drugs is ever present. Thus, new treatment options are needed for this infection. A new potential antifungal drug target is acetohydroxyacid synthase (AHAS; EC 2.2.1.6), the first enzyme in the branched chain amino acid biosynthesis pathway, and a target for many commercial herbicides. In this study, we have expressed, purified and characterised the catalytic subunit of AHAS from A. fumigatus and determined the inhibition constants for several known herbicides. The most potent of these, penoxsulam and metosulam, have Ki values of 1.8 ± 0.9 nM and 1.4 ± 0.2 nM, respectively. Molecular modelling shows that these compounds are likely to bind into the herbicide binding pocket in a mode similar to Candida albicans AHAS. We have also shown that these two compounds inhibit A. fumigatus growth at a concentration of 25 µg/mL. Thus, AHAS inhibitors are promising leads for the development of new anti-aspergillosis therapeutics.


Assuntos
Acetolactato Sintase , Antifúngicos/química , Aspergillus fumigatus/enzimologia , Proteínas Fúngicas , Herbicidas/química , Pirimidinas/química , Sulfonamidas/química , Triazóis/química , Uridina/análogos & derivados , Acetolactato Sintase/antagonistas & inibidores , Acetolactato Sintase/química , Candida albicans/enzimologia , Proteínas Fúngicas/antagonistas & inibidores , Proteínas Fúngicas/química , Uridina/química
3.
Curr Oncol ; 25(1): e99-e102, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29507502

RESUMO

Progressive multifocal leukoencephalopathy (pml) is a rare demyelinating disease of the central nervous system that most often affects immunocompromised individuals. It is caused by the reactivation of the John Cunningham virus (jcv), which is found in latent form in the majority of adults. We describe a 59-year-old man with multiple myeloma who developed severe neurological deficits during treatment with ixazomib-based chemotherapy. A diagnosis of pml was established with gadolinium-enhanced magnetic resonance imaging (mri) and by detection of jcv in the cerebrospinal fluid. Despite cessation of chemotherapy and treatment with mirtazapine, he had an inexorable neurological decline and died two months after presenting to hospital. Multiple myeloma and its treatments can predispose patients to opportunistic infections including pml. Although there have been case reports of pml in patients with multiple myeloma treated with bortezomib (a different proteosome inhibitor), this is, to our knowledge, the first documented case of pml in a patient treated with a regimen that includes ixazomib.

4.
Acta Physiol (Oxf) ; 221(1): 44-58, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28296171

RESUMO

AIM: Reductions in voltage-gated sodium channel (Nav1.5) function/expression provide a slowed-conduction substrate for cardiac arrhythmias. Nedd4-2, which is activated by calcium, post-translationally modulates Nav1.5. We aim to investigate whether elevated intracellular calcium ([Ca2+ ]i ) reduces Nav1.5 through Nedd4-2 and its role in heart failure (HF). METHODS: Using a combination of biochemical, electrophysiological, cellular and in vivo methods, we tested the effect and mechanism of calcium on Nedd4-2 and in turn Nav1.5. RESULTS: Increased [Ca2+ ]i , following 24-h ionomycin treatment, decreased sodium current (INa ) density and Nav1.5 protein without altering its mRNA in both neonatal rat cardiomyocytes (NRCMs) and HEK 293 cells stably expressing Nav1.5. The calcium chelator BAPTA-AM restored the reduced Nav1.5 and INa in NRCMs pre-treated by ionomycin. Nav1.5 was decreased by Nedd4-2 transfection and further decreased by 6-h ionomycin treatment. These effects were not observed in cells transfected with the catalytically inactive mutant, Nedd4-2 C801S, or with Y1977A-Nav1.5 mutant containing the impaired Nedd4-2 binding motif. Furthermore, elevated [Ca2+ ]i increased Nedd4-2, the interaction between Nedd4-2 and Nav1.5, and Nav1.5 ubiquitination. Nav1.5 protein is decreased, whereas Nedd4-2 is increased in volume-overload HF rat hearts, with increased co-localization of Nav1.5 with ubiquitin or Nedd4-2 as indicated by immunofluorescence staining. BAPTA-AM rescued the reduced Nav1.5 protein, INa and increased Nedd4-2 in hypertrophied NRCMs induced by isoproterenol or angiotensin II. CONCLUSION: Calcium-mediated increases in Nedd4-2 downregulate Nav1.5 by ubiquitination. Nav1.5 is downregulated and co-localizes with Nedd4-2 and ubiquitin in failing rat heart. These data suggest a role of Nedd4-2 in Nav1.5 downregulation in HF.


Assuntos
Cálcio/farmacologia , Insuficiência Cardíaca/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Ubiquitina-Proteína Ligases Nedd4/metabolismo , Animais , Cálcio/metabolismo , Células HEK293 , Humanos , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Processamento de Proteína Pós-Traducional/fisiologia , Ratos , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/fisiologia , Regulação para Cima
5.
Child Care Health Dev ; 43(1): 67-74, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27696503

RESUMO

BACKGROUND/OBJECTIVES: Children with atopic dermatitis are at increased risk of both general behaviour problems, and those specific to the condition and its treatment. This can hamper the ability of parents to carry out treatment and manage the condition effectively. To date, there is no published instrument available to assess child behaviour difficulties in the context of atopic dermatitis management. Our aim was to develop a reliable and valid instrument to assess atopic dermatitis-specific child behaviour problems, and parents' self-efficacy (confidence) for managing these behaviours. METHODS: The Eczema Behaviour Checklist (EBC) was developed as a 25-item questionnaire to measure (i) extent of behaviour problems (EBC Extent scale), and (ii) parents' self-efficacy for managing behaviour problems (EBC Confidence scale), in the context of child atopic dermatitis management. A community-based sample of 292 parents completed the EBC, measures of general behaviour difficulties, self-efficacy with atopic dermatitis management and use of dysfunctional parenting strategies. RESULTS: There was satisfactory internal consistency and construct validity for EBC Extent and Confidence scales. There was a negative correlation between atopic dermatitis-specific behaviour problems and parents' self-efficacy for dealing with behaviours (r = -.53, p < .001). Factor analyses revealed a three-factor structure for both scales: (i) treatment-related behaviours; (ii) symptom-related behaviours; and (iii) behaviours related to impact of the illness. Variation in parents' self-efficacy for managing their child's atopic dermatitis was explained by intensity of illness-specific child behaviour problems and parents' self-efficacy for dealing with the behaviours. CONCLUSIONS: The new measure of atopic dermatitis-specific child behaviour problems was a stronger predictor of parents' self-efficacy for managing their child's condition than was the measure of general child behaviour difficulties. Results provide preliminary evidence of reliability and validity of the EBC, which has potential for use in clinical and research settings, and warrant further psychometric evaluation.


Assuntos
Transtornos do Comportamento Infantil/diagnóstico , Transtornos do Comportamento Infantil/etiologia , Dermatite Atópica/psicologia , Adulto , Lista de Checagem , Criança , Comportamento Infantil , Pré-Escolar , Dermatite Atópica/terapia , Fármacos Dermatológicos/efeitos adversos , Feminino , Humanos , Masculino , Relações Pais-Filho , Poder Familiar/psicologia , Psicometria , Reprodutibilidade dos Testes , Autoeficácia , Índice de Gravidade de Doença , Higiene da Pele/métodos , Higiene da Pele/psicologia , Fatores Socioeconômicos , Inquéritos e Questionários
6.
Acta Physiol (Oxf) ; 214(3): 361-75, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25850710

RESUMO

AIMS: Cardiac ryanodine receptor mutations are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), and some, including RyR2-P2328S, also predispose to atrial fibrillation. Recent work associates reduced atrial Nav 1.5 currents in homozygous RyR2-P2328S (RyR2(S/S) ) mice with slowed conduction and increased arrhythmogenicity. Yet clinically, and in murine models, the Nav 1.5 blocker flecainide reduces ventricular arrhythmogenicity in CPVT. We aimed to determine whether, and how, flecainide influences atrial arrhythmogenicity in RyR2(S/S) mice and their wild-type (WT) littermates. METHODS: We explored effects of 1 µm flecainide on WT and RyR2(S/S) atria. Arrhythmic incidence, action potential (AP) conduction velocity (CV), atrial effective refractory period (AERP) and AP wavelength (λ = CV × AERP) were measured using multi-electrode array recordings in Langendorff-perfused hearts; Na(+) currents (INa ) were recorded using loose patch clamping of superfused atria. RESULTS: RyR2(S/S) showed more frequent atrial arrhythmias, slower CV, reduced INa and unchanged AERP compared to WT. Flecainide was anti-arrhythmic in RyR2(S/S) but pro-arrhythmic in WT. It increased INa in RyR2(S/S) atria, whereas it reduced INa as expected in WT. It increased AERP while sparing CV in RyR2(S/S) , but reduced CV while sparing AERP in WT. Thus, RyR2(S/S) hearts have low λ relative to WT; flecainide then increases λ in RyR2(S/S) but decreases λ in WT. CONCLUSIONS: Flecainide (1 µm) rescues the RyR2-P2328S atrial arrhythmogenic phenotype by restoring compromised INa and λ, changes recently attributed to increased sarcoplasmic reticular Ca(2+) release. This contrasts with the increased arrhythmic incidence and reduced INa and λ with flecainide in WT.


Assuntos
Fibrilação Atrial/metabolismo , Flecainida/administração & dosagem , Potenciais da Membrana/efeitos dos fármacos , Canal de Sódio Disparado por Voltagem NAV1.5/efeitos dos fármacos , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Sódio/metabolismo , Animais , Antiarrítmicos/administração & dosagem , Fibrilação Atrial/diagnóstico , Ativação do Canal Iônico/efeitos dos fármacos , Camundongos , Mutação , Resultado do Tratamento , Bloqueadores do Canal de Sódio Disparado por Voltagem/administração & dosagem
8.
Acta Physiol (Oxf) ; 211(4): 559-73, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24913289

RESUMO

AIM: To test a hypothesis attributing arrhythmia in Brugada Syndrome to right ventricular (RV) outflow tract (RVOT) conduction abnormalities arising from Nav 1.5 insufficiency and fibrotic change. METHODS: Arrhythmic properties of Langendorff-perfused Scn5a+/- and wild-type mouse hearts were correlated with ventricular effective refractory periods (VERPs), multi-electrode array (MEA) measurements of action potential (AP) conduction velocities and dispersions in conduction direction (CD), Nav 1.5 expression levels, and fibrotic change, as measured at the RVOT and RV. Two-way anova was used to test for both independent and interacting effects of anatomical region and genotype on these parameters. RESULTS: Scn5a+/- hearts showed greater arrhythmic frequencies during programmed electrical stimulation at the RVOT but not the RV. The Scn5a+/- genotype caused an independent increase of VERP regardless of whether the recording site was the RVOT or RV. Effective AP conduction velocities (CV†s), derived from fitting regression planes to arrays of observed local activation times were reduced in Scn5a+/- hearts and at the RVOT independently. AP conduction velocity magnitudes derived by averaging MEA results from local vector analyses, CV*, were reduced by the Scn5a+/- genotype alone. In contrast, dispersions in conduction direction, were greater in the RVOT than the RV, when the atrioventricular node was used as the pacing site. The observed reductions in Nav 1.5 expression were attributable to Scn5a+/-, whereas increased levels of fibrosis were associated with the RVOT. CONCLUSIONS: The Scn5a+/- RVOT recapitulates clinical findings of increased arrhythmogenicity through reduced CV† reflecting reduced CV* attributable to reduced Nav 1.5 expression and increased CD attributable to fibrosis.


Assuntos
Arritmias Cardíacas/fisiopatologia , Síndrome de Brugada/fisiopatologia , Sistema de Condução Cardíaco/fisiopatologia , Coração/fisiopatologia , Potenciais de Ação/fisiologia , Animais , Western Blotting , Modelos Animais de Doenças , Eletrofisiologia , Feminino , Masculino , Camundongos , Camundongos Mutantes , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Técnicas de Cultura de Órgãos
9.
BMC Nephrol ; 14: 250, 2013 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-24225349

RESUMO

BACKGROUND: The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (eGFR) has been widely integrated into clinical practice. Although useful in screening for CKD, its' application in critically ill patients with normal plasma creatinine concentrations remains uncertain. The aim of this study was to assess the performance of CKD-EPI eGFR in comparison to creatinine clearance (CLCR) in this setting. METHODS: This prospective observational study was performed in a tertiary level, university affiliated intensive care unit (ICU). Study participants had to have an expected ICU length of stay > 24 hours, a plasma creatinine concentration < 121 µmol/L, and no history of prior renal replacement therapy or CKD. CKD-EPI eGFR was compared against 8-hour measured urinary CLCR. Data capture occurred within 48 hours of admission. RESULTS: One hundred and ten patients (n = 110) were enrolled in the study. 63.6% were male, the mean age was 50.9 (16.9) years, 57.3% received invasive mechanical ventilation, and 30% required vasopressor support. The mean CLCR was 125 (45.1) ml/min/1.73 m(2), compared to a CKD-EPI eGFR of 101 (23.7) ml/min/1.73 m(2) (P < 0.001). Moderate correlation was evident (r = 0.72), although there was significant bias and imprecision (24.4 +/- 32.5 ml/min/1.73 m(2)). In those patients with a CKD-EPI eGFR between 60-119 ml/min/1.73 m(2) (n = 77), 41.6% displayed augmented renal clearance (CLCR ≥ 130 ml/min/1.73 m(2)), while 7.8% had a CLCR < 60 ml/min/1.73 m(2). CONCLUSIONS: These data suggest CKD-EPI eGFR and measured CLCR produce significantly disparate results when estimating renal function in this population. Clinicians should consider carefully which value they employ in clinical practice, particularly drug dose modification.


Assuntos
Creatinina/sangue , Cuidados Críticos/estatística & dados numéricos , Taxa de Filtração Glomerular , Testes de Função Renal/estatística & dados numéricos , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/epidemiologia , Austrália/epidemiologia , Estado Terminal , Feminino , Humanos , Unidades de Terapia Intensiva/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Prevalência , Valores de Referência , Insuficiência Renal Crônica/sangue , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
Acta Physiol (Oxf) ; 207(2): 308-23, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22958452

RESUMO

AIM: RyR2 mutations are associated with catecholaminergic polymorphic tachycardia, a condition characterized by ventricular and atrial arrhythmias. The present experiments investigate the atrial electrophysiology of homozygotic murine RyR2-P2328S (RyR2(S/S)) hearts for ectopic triggering events and for conduction abnormalities that might provide a re-entrant substrate. METHODS: Electrocardiograph recordings were made from regularly stimulated RyR2(S/S) and wild type (WT) hearts, perfused using a novel modified Langendorff preparation. This permitted the simultaneous use of either floating intracellular microelectrodes to measure action potential (AP) parameters, or a multielectrode array to measure epicardial conduction velocity (CV). RESULTS: RyR2(S/S) showed frequent sustained tachyarrhythmias, delayed afterdepolarizations and ectopic APs, increased interatrial conduction delays, reduced epicardial CVs and reduced maximum rates of AP depolarization ((dV/dt)(max)), despite similar effective refractory periods, AP durations and AP amplitudes. Effective interatrial CVs and (dV/dt)(max) values of APs following ectopic (S2) stimulation were lower than those of APs following regular stimulation and decreased with shortening S1S2 intervals. However, although RyR2(S/S) atria showed arrhythmias over a wider range of S1S2 intervals, the interatrial CV and (dV/dt)(max) of S2 APs provoking such arrhythmias were similar in RyR2(S/S) and WT. CONCLUSIONS: These results suggest that abnormal intracellular Ca(2+) homoeostasis produces both arrhythmic triggers and a slow-conducting arrhythmic substrate in RyR2(S/S) atria. A similar mechanism might also contribute to arrhythmogenesis in other conditions, associated with diastolic Ca(2+) release, such as atrial fibrillation.


Assuntos
Arritmias Cardíacas/fisiopatologia , Cálcio/metabolismo , Átrios do Coração/fisiopatologia , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Potenciais de Ação/fisiologia , Animais , Arritmias Cardíacas/metabolismo , Eletrocardiografia , Átrios do Coração/metabolismo , Camundongos , Camundongos Mutantes , Técnicas de Cultura de Órgãos , Canal de Liberação de Cálcio do Receptor de Rianodina/genética
11.
mBio ; 2(1): e00342-10, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21304167

RESUMO

Cryptococcus gattii recently emerged as the causative agent of cryptococcosis in healthy individuals in western North America, despite previous characterization of the fungus as a pathogen in tropical or subtropical regions. As a foundation to study the genetics of virulence in this pathogen, we sequenced the genomes of a strain (WM276) representing the predominant global molecular type (VGI) and a clinical strain (R265) of the major genotype (VGIIa) causing disease in North America. We compared these C. gattii genomes with each other and with the genomes of representative strains of the two varieties of Cryptococcus neoformans that generally cause disease in immunocompromised people. Our comparisons included chromosome alignments, analysis of gene content and gene family evolution, and comparative genome hybridization (CGH). These studies revealed that the genomes of the two representative C. gattii strains (genotypes VGI and VGIIa) are colinear for the majority of chromosomes, with some minor rearrangements. However, multiortholog phylogenetic analysis and an evaluation of gene/sequence conservation support the existence of speciation within the C. gattii complex. More extensive chromosome rearrangements were observed upon comparison of the C. gattii and the C. neoformans genomes. Finally, CGH revealed considerable variation in clinical and environmental isolates as well as changes in chromosome copy numbers in C. gattii isolates displaying fluconazole heteroresistance.


Assuntos
Criptococose/imunologia , Criptococose/microbiologia , Cryptococcus gattii/genética , Variação Genética , Genoma Bacteriano , Animais , Antifúngicos/farmacologia , Cryptococcus gattii/classificação , Cryptococcus gattii/efeitos dos fármacos , Cryptococcus gattii/isolamento & purificação , Surtos de Doenças , Evolução Molecular , Feminino , Genótipo , Interações Hospedeiro-Patógeno , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , América do Norte/epidemiologia , Filogenia
12.
J Appl Physiol (1985) ; 110(3): 610-8, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21148341

RESUMO

Hyperoxia has been shown to attenuate the increase in pulmonary artery (PA) pressure associated with immersed exercise in thermoneutral water, which could serve as a possible preventive strategy for the development of immersion pulmonary edema (IPE). We tested the hypothesis that the same is true during exercise in cold water. Six healthy volunteers instrumented with arterial and PA catheters were studied during two 16-min exercise trials during prone immersion in cold water (19.9-20.9°C) in normoxia [0.21 atmospheres absolute (ATA)] and hyperoxia (1.75 ATA) at 4.7 ATA. Heart rate (HR), Fick cardiac output (CO), mean arterial pressure (MAP), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), central venous pressure (CVP), arterial and venous blood gases, and ventilatory parameters were measured both early (E, 5-6 min) and late (L, 15-16 min) in exercise. During exercise at an average oxygen consumption rate (Vo(2)) of 2.38 l/min, [corrected] CO, CVP, and pulmonary vascular resistance were not affected by inspired (Vo(2)) [corrected] or exercise duration. Minute ventilation (Ve), alveolar ventilation (Va), and ventilation frequency (f) were significantly lower in hyperoxia compared with normoxia (mean ± SD: Ve 58.8 ± 8.0 vs. 65.1 ± 9.2, P = 0.003; Va 40.2 ± 5.4 vs. 44.2 ± 9.0, P = 0.01; f 25.4 ± 5.4 vs. 27.2 ± 4.2, P = 0.04). Mixed venous pH was lower in hyperoxia compared with normoxia (7.17 ± 0.07 vs. 7.20 ± 0.07), and this result was significant early in exercise (P = 0.002). There was no difference in mean PAP (MPAP: 28.28 ± 8.1 and 29.09 ± 14.3 mmHg) or PAWP (18.0 ± 7.6 and 18.7 ± 8.7 mmHg) between normoxia and hyperoxia, respectively. PAWP decreased from early to late exercise in hyperoxia (P = 0.002). These results suggest that the increase in pulmonary vascular pressures associated with cold water immersion is not attenuated with hyperoxia.


Assuntos
Temperatura Baixa/efeitos adversos , Exercício Físico , Hiperóxia/complicações , Hiperóxia/fisiopatologia , Hipertensão Pulmonar/fisiopatologia , Imersão/efeitos adversos , Edema Pulmonar/fisiopatologia , Adulto , Feminino , Humanos , Hipertensão Pulmonar/complicações , Masculino , Pessoa de Meia-Idade , Decúbito Ventral , Edema Pulmonar/complicações , Adulto Jovem
13.
Acta Physiol (Oxf) ; 198(2): 143-58, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19886909

RESUMO

AIM: To investigate the effect of increases in extracellular Ca(2+) entry produced by the L-type Ca(2+) channel agonist FPL-64176 (FPL) upon acute atrial arrhythmogenesis in intact Langendorff-perfused mouse hearts and its dependence upon diastolic Ca(2+) release from sarcoplasmic reticular Ca(2+) stores. METHODS: Confocal microscope studies of Fluo-3 fluorescence in isolated atrial myocytes were performed in parallel with electrophysiological examination of Langendorff-perfused mouse hearts. RESULTS: Atrial myocytes stimulated at 1 Hz and exposed to FPL (0.1 microm) initially showed (<10 min) frequent, often multiple, diastolic peaks following the evoked Ca(2+) transients whose amplitudes remained close to control values. With continued pacing (>10 min) this reverted to a regular pattern of evoked transients with increased amplitudes but in which diastolic peaks were absent. Higher FPL concentrations (1.0 microm) produced sustained and irregular patterns of cytosolic Ca(2+) activity, independent of pacing. Nifedipine (0.5 microm), and caffeine (1.0 mm) and cyclopiazonic acid (CPA) (0.15 microm) pre-treatments respectively produced immediate and gradual reductions in the F/F(0) peaks. Such nifedipine and caffeine, or CPA pre-treatments, abolished, or reduced, the effects of 0.1 and 1.0 microm FPL on cytosolic Ca(2+) signals. FPL (1.0 microm) increased the incidence of atrial tachycardia and fibrillation in intact Langendorff-perfused hearts without altering atrial effective refractory periods. These effects were inhibited by nifedipine and caffeine, and reduced by CPA. CONCLUSION: Enhanced extracellular Ca(2+) entry exerts acute atrial arrhythmogenic effects that is nevertheless dependent upon diastolic Ca(2+) release. These findings complement reports that associate established, chronic, atrial arrhythmogenesis with decreased overall inward Ca(2+) current.


Assuntos
Antiarrítmicos/farmacologia , Arritmias Cardíacas/tratamento farmacológico , Cálcio/metabolismo , Coração/efeitos dos fármacos , Compostos de Anilina/farmacologia , Animais , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Cafeína/farmacologia , Canais de Cálcio Tipo L/metabolismo , Sinalização do Cálcio , Coração/fisiopatologia , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/fisiopatologia , Camundongos , Miócitos Cardíacos/efeitos dos fármacos , Nifedipino/farmacologia , Pirróis/farmacologia , Xantenos/farmacologia
15.
Acta Physiol (Oxf) ; 189(1): 33-46, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17280555

RESUMO

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.


Assuntos
Arritmias Cardíacas/fisiopatologia , Hipopotassemia/fisiopatologia , Disfunção Ventricular Esquerda/fisiopatologia , Potenciais de Ação/fisiologia , Animais , Bradicardia/fisiopatologia , Estimulação Elétrica , Endocárdio/fisiopatologia , Feminino , Hipopotassemia/complicações , Masculino , Camundongos , Miócitos Cardíacos/fisiologia , Técnicas de Patch-Clamp , Pericárdio/fisiopatologia , Potássio/fisiologia , Fatores de Risco , Taquicardia Ventricular/fisiopatologia , Torsades de Pointes/etiologia , Torsades de Pointes/fisiopatologia
16.
Br J Cancer ; 88(8): 1263-70, 2003 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-12698194

RESUMO

To test the hypothesis that altered expression of BRCA1 protein may play an important role in sporadic breast cancer development, 50 randomly selected primary breast cancers (frozen sections, 5 years' median follow-up) were immunolabelled with two monoclonal BRCA1 antibodies (MS110 and MS13). MS110 labelling was exclusively nuclear showing no relation to outcome or tumour pathology. Western blotting demonstrated crossreactivity, suggesting antibody nonspecificity. MS13 labelling was predominantly cytoplasmic. Intense labelling predicted decreased overall survival (P=0.012), disease-free survival (P=0.029), oestrogen receptor negativity (P=0.0004) and c-erbB-2 overexpression (P=0.006). Western blotting detected a 110 kDa molecule consistent with BRCA1 delta11b splice variant. BRCA1 protein is postulated to function as a tumour suppressor. We demonstrate cytoplasmic localisation in sporadic breast cancer suggesting excess delta11b splice variant production, reduced production of full-length BRCA1 and thus postulate reduced tumour suppressor activity. BRCA1 protein appears to have a significant role in both sporadic and hereditary breast cancers.


Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/genética , Adulto , Idoso , Neoplasias da Mama/patologia , Neoplasias da Mama/cirurgia , Linhagem Celular Tumoral , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade
17.
J Paediatr Child Health ; 38(1): 23-6, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11869396

RESUMO

OBJECTIVE: To assess the quality of professional telephone advice given to parents with sick children. METHODS: All hospitals with an emergency department and a paediatric ward and a designated child health telephone advice line in the greater Brisbane region were invited to participate in the study. Case scenarios involving a febrile baby, a 14-month-old with gastroenteritis and an 18-month-old with a head injury were used three times with each institution. Each of the cases should have elicited a response indicating the need for urgent medical attention. A research assistant presented the symptoms in accordance with the questions of the telephone advice-giver. Aspects of the call were recorded, including time between call made and access to advice-giver, profession of advice-giver, identifying details sought by advice-giver, questions asked about the case presented, length of call, and advice-given. RESULTS: Of the 10 hospitals asked, six agreed to participate. Included in the study were two paediatric hospitals, two general public hospitals, one private hospital, and a Statewide-designated child health telephone advice line. Calls were generally attended to promptly. Only 37 (68.5%) of the advisers recognized the urgency of the case scenarios, with the febrile infant having the least likelihood of eliciting the correct advice (39%). Doctors gave more reliable advice than nurses in the fever scenario, but not in the other cases. CONCLUSIONS: Telephone advice to parents with sick children is easily accessible, but is often dangerously inappropriate. There is a need for tighter quality control and/or for a centralised telephone advice line to prevent inappropriate advice being given to parents.


Assuntos
Pediatria/normas , Relações Profissional-Paciente , Garantia da Qualidade dos Cuidados de Saúde , Consulta Remota/normas , Telefone , Criança , Traumatismos Craniocerebrais/terapia , Desidratação/terapia , Febre/terapia , Humanos , New South Wales
18.
Genetics ; 157(1): 119-31, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11139496

RESUMO

The ability to utilize formamide as a sole nitrogen source has been found in numerous fungi. We have cloned the fmdS gene encoding a formamidase from Aspergillus nidulans and found that it belongs to a highly conserved family of proteins separate from the major amidase families. The expression of fmdS is primarily regulated via AreA-mediated nitrogen metabolite repression and does not require the addition of exogenous inducer. Consistent with this, deletion analysis of the 5' region of fmdS has confirmed the presence of multiple AreA-binding sites containing a characteristic core GATA sequence. Under carbon starvation conditions the response to nitrogen starvation is eliminated, indicating that the lack of a carbon source may result in inactivation of AreA. Sequence analysis and isolation of cDNAs show that a gene of unknown function lies directly 5' of fmdS with its transcript overlapping the fmdS coding region. Disruption of the 5' gene and analysis of the effects of overexpression of this gene on fmdS expression has shown that expression of this upstream gene interferes with fmdS transcription, resulting in a strong dependence on AreA activation for expression. Therefore the relative position of these two genes is essential for normal regulation of fmdS.


Assuntos
Amidoidrolases/genética , Aspergillus nidulans/enzimologia , Aspergillus nidulans/genética , Genes Fúngicos , Sequência de Aminoácidos , Aspergillus nidulans/metabolismo , Sequência de Bases , Carbono/metabolismo , Clonagem Molecular , Sequência Conservada , Primers do DNA/genética , DNA Fúngico/genética , Formamidas/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Dados de Sequência Molecular , Mutação , Nitrogênio/metabolismo , Homologia de Sequência de Aminoácidos , Transcrição Gênica
19.
Child Abuse Negl ; 24(11): 1399-429, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11128173

RESUMO

OBJECTIVE: This study aimed to: (1) Assess the community utility of a screening tool to identify families with child abuse or neglect risk factors in the immediate postnatal period (2) Determine the social validity and effectiveness of a home visiting program using community child health nurses and offering social work services for identified families, and (3) Identify factors in the immediate postnatal period associated with the child's environment that predict poor adjustment to the parenting role. METHOD: A randomized controlled trial using a cohort of 181 families was undertaken to evaluate the impact of a home visiting program. Mothers were recruited in the immediate postnatal period and allocated either into the home visiting program or into a comparison group. The research design required self-identification into the study by providing positive responses to a range of risk factors. A repeated measures design was used to test parenting stress and maternal depression from the immediate postnatal period to 12-month follow-up and physical child abuse potential to 18-month follow-up. To test whether measures taken in the immediate postnatal period were predictive for poor adjustment to the parenting role, a linear regression model was used. RESULTS: The screening procedure was shown to have utility in the context of recruitment to a research trial and mothers were willing to accept the home visiting program examined by this study from the immediate postnatal period. From as early as 6 weeks the program demonstrated ability to impact positively on maternal, infant, family, and home environment variables (testing 90 randomly allocated intervention vs. 91 comparison families). At follow-up, parental adjustment variables were not significantly different between groups (testing the remaining 68 (75.5%) intervention vs. 70 (76.9%) comparison families) and home environment assessment scores had converged. Predictive analysis of factors measured in the immediate postnatal period revealed an absence of any predictive value to demographic characteristics, which secondary prevention efforts typically target. CONCLUSIONS: Follow-up evaluation did not demonstrate a positive impact on parenting stress, parenting competence, or quality of the home environment confirming the need to test early program success on longer term outcomes. Further, thestudy not only demonstrated that there was a relationship between maternal, family and environmental factors identified in the immediate postnatal period. and adjustment to the parenting role, but also challenged demographic targeting for child abuse and neglect risk. At the same time, the immediate postnatal period presented an exciting window of opportunity to access high-risk families who may otherwise have become marginalized from traditional services.


Assuntos
Maus-Tratos Infantis/prevenção & controle , Depressão Pós-Parto , Visita Domiciliar , Relações Mãe-Filho , Serviço Social , Adaptação Psicológica , Adolescente , Adulto , Feminino , Humanos , Recém-Nascido , Programas de Rastreamento , Poder Familiar , Fatores de Risco , Estresse Psicológico
20.
J Paediatr Child Health ; 36(6): 555-62, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11115031

RESUMO

OBJECTIVE: To evaluate the efficacy of an early home-based intervention on the quality of maternal-infant attachment, maternal mood and child health parameters in a cohort of vulnerable families. METHODOLOGY: A total of 181 families were recruited to the study in the immediate postnatal period on the basis of a self report questionnaire relating to known family vulnerability factors. Families were assigned randomly to intervention (90), or control (91) groups. The intervention group received a series of home visits from a child health nurse (weekly to 6 weeks, fortnightly to 3 months), with a subgroup receiving home based short-term dynamic therapy from a social worker. Parent/family function was assessed at inception and at 4 months by the Parenting Stress Index and the Edinburgh Post Natal Depression Scale. At 4 months the quality of the home environment was assessed, utilizing the Home Observation for Measurement of the Environment Inventory, as were child and family health parameters and satisfaction with the community child health service. RESULTS: At 4 month follow-up, 160 families (80 intervention, 80 control) were available for assessment. The intervention improved family functioning at 4 months. All aspects of the home environment, including the quality of maternal-infant attachment and mothers' relationship with their child, were significantly enhanced. In particular, significant and positive differences were found in parenting with the intervention group feeling less restrictions imposed by the parenting role, greater sense of competence in parenting, greater acceptability of the child, and the child being more likely to provide positive reinforcement to the parent. Early differences in maternal mood were not maintained at 4 months. Various child health parameters were enhanced including immunization status, fewer parent-reported injuries and bruising, and researcher confirmed lack of smoking in the house or around the infant. The families were consistently more satisfied with their community health service. CONCLUSIONS: This form of early home based intervention targeted to vulnerable families promotes an environment conducive for infant mental and general health and hence long-term psychological and physical well-being, and is highly valued by the families who receive it.


Assuntos
Saúde da Família , Serviços de Assistência Domiciliar , Centros de Saúde Materno-Infantil , Cuidado Pós-Natal , Adulto , Humanos , Lactente , Bem-Estar do Lactente
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