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1.
Med J Malaysia ; 78(1): 80-86, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36715196

RESUMO

INTRODUCTION: The COVID-19 pandemic has reached a phase where many have been infected at least once. Healthcare workers were not spared from being infected. This study aimed to determine the period prevalence of COVID-19 among the paediatric healthcare workers in Negeri Sembilan as the country transitioned into an endemic phase of the pandemic. Additionally, we investigate potential sociodemographic and occupational characteristics associated with SARS-CoV-2 infection among healthcare workers. MATERIALS AND METHODS: A cross-sectional study was conducted among the healthcare workers in the paediatric department at three public specialist hospitals in Negeri Sembilan between 15 and 21 April 2022. Data were collected through a self-administered questionnaire. RESULTS: Out of the 504 eligible healthcare workers, 493 participated in this study (response rate 97.8%). The overall prevalence of COVID-19 (11 March 2020-15 April 2022) among healthcare workers was 50.9%. The majority (80.1%) were infected during the Omicron wave two months before the survey. Household contacts accounted for 35.9% of infection sources. The proportion of non-doctors in the COVID-19-infected group was significantly higher compared to the non-infected group (74.1% vs 64.0%, p=0.016). The COVID-19-infected group had a higher proportion of schoolgoing children (44.6% vs 30.6%, p=0.001) and children who attended pre-school/sent to the babysitter (49.0% vs 24.4%, p<0.001). There were no significant differences between infection rates among the healthcare workers working in the tertiary hospital and the district hospitals. There were also no significant differences in the proportion of COVID-19- infected doctors and nurses when analysed by seniority. CONCLUSION: Our study provided an estimate on the prevalence of COVID-19 among paediatric healthcare workers in Negeri Sembilan and the factors associated with infection, which captures the extent and magnitude of this pandemic on the state's paediatric department. Most infections resulted from household contact, with a higher proportion of infected healthcare workers having young children.


Assuntos
COVID-19 , Humanos , Criança , Pré-Escolar , COVID-19/epidemiologia , Estudos Transversais , Prevalência , SARS-CoV-2 , Pandemias , Pessoal de Saúde
2.
Med J Malaysia ; 74(4): 281-287, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31424034

RESUMO

INTRODUCTION: The average incidence of spina bifida (SB) in Malaysia is 0.43 among 1,000 live births. The burden of the disease and its impact on the overall development and health though tremendously improved, remains significant. Therefore, current patient management strategies must include quality of life (QOL) measures. METHODS: This was a prospective, cross-sectional study on spina bifida children aged 5-20 years, attending the paediatric spina bifida clinics of Universiti Kebangsaan Malaysia Medical Centre Kuala Lumpur and Hospital Tuanku Jaanku Seremban. Scores were obtained using the validated disease specific Parkin QOL questionnaire. Univariate and multivariate analysis were used to investigate factors that were determinants for these outcomes. Results were expressed as beta coefficient and 95% confidence intervals (95%CI). RESULTS: A total of 54 children and adolescents aged between 5-20 years completed the questionnaires. Presence of neurogenic bowel (p=0.003), neurogenic bladder (p=0.041), shunt (p=0.044), non-ambulators (p=0.007) and being the only child in the family (p=0.037) were associated with lower QOL scores. Multivariate analysis showed presence of neurogenic bowel (ß=0.375, 95%CI: 0.00, 0.15) and being the only child in the family (ß=0.250, 95%CI: 0.04, 0.17) explained 22.1% of the variance in the QOL mean percentage scores. CONCLUSION: Being a single child in the family was the only socio-demographic variable associated with lower QOL scores. Although several clinical factors appeared to contribute significantly to QOL in spina bifida children, the presence of neurogenic bowel had the greatest impact.


Assuntos
Qualidade de Vida/psicologia , Disrafismo Espinal/psicologia , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Feminino , Indicadores Básicos de Saúde , Humanos , Modelos Lineares , Malásia , Masculino , Intestino Neurogênico/etiologia , Intestino Neurogênico/psicologia , Filho Único/psicologia , Estudos Prospectivos , Disrafismo Espinal/complicações , Disrafismo Espinal/fisiopatologia , Disrafismo Espinal/terapia , Adulto Jovem
3.
Acta Oncol ; 57(10): 1293-1302, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29932784

RESUMO

BACKGROUND: Group face-to-face and individual internet-based mindfulness-based cognitive therapy (MBCT and eMBCT) have been demonstrated to reduce psychological distress for distressed cancer patients in a randomized controlled trial (RCT). This study focused on the long-term effects of this RCT during the nine-month follow-up period, and on possible predictors, moderators and working mechanisms. METHODS: Distressed cancer patients (n = 245) were randomized to MBCT or eMBCT. Data were collected at baseline, post-treatment, three- and nine-month follow-up. Data were analyzed with linear mixed effect models and (hierarchical) linear regressions. RESULTS: Analyses revealed long-term reductions in psychological distress and rumination, and long-term increases in positive mental health and mental health-related quality of life (QoL) in both interventions over the course of the nine-month follow-up. Interestingly, patients reported less psychological distress in the follow-up period after eMBCT in comparison to MBCT. Less psychological distress, rumination and neuroticism, and more extraversion and agreeableness at baseline predicted less psychological distress at the nine-month follow-up after both interventions. Less mindful and conscientious patients at baseline benefited more from eMBCT than from MBCT. Regarding working mechanisms, changes in mindfulness skills, fear of cancer recurrence and rumination during both interventions predicted less psychological distress at follow-up. CONCLUSIONS: Our findings suggest most improvements in cancer patients' increase over time after both interventions. Furthermore, patients seemed to benefit more from eMBCT than MBCT based on psychological distress levels, especially those patients with low levels of mindfulness skills and conscientiousness.


Assuntos
Terapia Cognitivo-Comportamental , Internet , Atenção Plena , Neoplasias/psicologia , Estresse Psicológico/terapia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida
4.
Psychooncology ; 27(3): 871-878, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29205675

RESUMO

OBJECTIVE: The mental burden of cancer might elicit additional health care utilization. However, it is unclear how psychiatric disorder and psychological distress relate to health care utilization. Therefore, this study explores associations between psychiatric disorder, psychological distress, and health care utilization. It was hypothesized that presence of psychiatric disorder and psychological distress was associated with increased health care utilization and costs. METHODS: The current study consisted of secondary analyses of baseline data of a larger randomized controlled trial. Two hundred forty-five mixed-cancer patients with at least mild symptoms of psychological distress (Hospital Anxiety and Depression Scale-T ≥ 11) were mainly recruited via online media, participating centers and patient associations. Patients were assessed with Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID-I) for depressive, anxiety, and/or adjustment disorder. Psychological distress was measured by the Hospital Anxiety and Depression Scale. Retrospective self-reported health care utilization in the past 3 months was collected. Associations between predictors and health care utilization in terms of incidence rate ratios (IRR) and costs per category (mental, primary, somatic, and complementary) were assessed by negative binomial, logistic, and gamma regression. RESULTS: Eighty-nine (36.3%) patients suffered from psychiatric disorder, which was associated with mental health care utilization (IRR = 1.63) and costs (OR = 3.11). We observed a nonsignificant trend of somatic health care utilization in patients with psychiatric disorder. Psychological distress was associated with mental health care utilization (IRR = 1.09) and costs (OR = 1.09). Psychological distress was also associated with complementary health care utilization (IRR = 1.03). CONCLUSION: Psychiatric disorder and psychological distress were associated with mental health care use and costs. Psychological distress was associated with complementary health care use. Adequate assessment and referral to mental health care might prevent unnecessary health care utilization.


Assuntos
Transtornos Mentais/epidemiologia , Neoplasias/epidemiologia , Estresse Psicológico/epidemiologia , Adulto , Idoso , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos
5.
Mol Pharm ; 13(12): 4199-4208, 2016 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-27806577

RESUMO

Intestinal absorption in human is routinely predicted in drug discovery using in vitro assays such as permeability in the Madin-Darby canine kidney cell line. In silico models trained on these data are used in drug discovery efforts to prioritize novel chemical targets for synthesis; however, their proprietary nature and the limited validation available, which is usually restricted to predicting in vitro permeability, are barriers to widespread adoption. Because of the categorical nature of the in vitro permeability assay, intrinsic assay variability, and the challenges often encountered when translating in vitro data to an in vivo drug property, validation based solely on in vitro data might not be a good characterization of the usefulness of the in silico tool. In this work, we analyze the performance of three different in silico models in predicting the in vitro and in vivo permeability of 300 marketed drugs and 86 discovery compounds. The models differ in their approach (mechanistic vs quantitative structure-activity relationship) and the degree of complexity; one of them is a linear equation based on seven simple physicochemical descriptors and is presented for the first time in this work. Results show that in silico models can be successfully used to complement the discovery toolbox for characterizing in vivo intestinal permeability, defined using fraction of dose absorbed in human (Fa) and human jejunal permeability (Peff). While the in vitro permeability models outperformed the in silico approach at predicting each of the in vivo end points explored, the gap in predictivity between the in vitro and the in vivo data was generally comparable to the gap between in silico and in vitro data. The in vitro and in silico approaches shared many of the same outliers, which can often be explained by the route of drug absorption (paracellular vs transcellular, active vs passive). Data suggest that the discovery process can greatly benefit from an early adoption of in silico models for predicting permeability as well as from a careful analysis of the in silico to in vivo disconnects.


Assuntos
Modelos Teóricos , Preparações Farmacêuticas/química , Preparações Farmacêuticas/metabolismo , Animais , Permeabilidade da Membrana Celular , Simulação por Computador , Cães , Humanos , Células Madin Darby de Rim Canino , Relação Quantitativa Estrutura-Atividade
6.
EBioMedicine ; 9: 257-277, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27333023

RESUMO

Dravet syndrome is a devastating genetic brain disorder caused by heterozygous loss-of-function mutation in the voltage-gated sodium channel gene SCN1A. There are currently no treatments, but the upregulation of SCN1A healthy allele represents an appealing therapeutic strategy. In this study we identified a novel, evolutionary conserved mechanism controlling the expression of SCN1A that is mediated by an antisense non-coding RNA (SCN1ANAT). Using oligonucleotide-based compounds (AntagoNATs) targeting SCN1ANAT we were able to induce specific upregulation of SCN1A both in vitro and in vivo, in the brain of Dravet knock-in mouse model and a non-human primate. AntagoNAT-mediated upregulation of Scn1a in postnatal Dravet mice led to significant improvements in seizure phenotype and excitability of hippocampal interneurons. These results further elucidate the pathophysiology of Dravet syndrome and outline a possible new approach for the treatment of this and other genetic disorders with similar etiology.


Assuntos
Encéfalo/metabolismo , Epilepsias Mioclônicas/patologia , Canal de Sódio Disparado por Voltagem NAV1.1/metabolismo , RNA Longo não Codificante/metabolismo , Alelos , Animais , Sequência de Bases , Comportamento Animal , Encéfalo/diagnóstico por imagem , Linhagem Celular , Chlorocebus aethiops , Modelos Animais de Doenças , Eletroencefalografia , Epilepsias Mioclônicas/genética , Epilepsias Mioclônicas/metabolismo , Expressão Gênica , Técnicas de Introdução de Genes , Hipocampo/fisiologia , Humanos , Técnicas In Vitro , Interneurônios/metabolismo , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Canal de Sódio Disparado por Voltagem NAV1.1/química , Canal de Sódio Disparado por Voltagem NAV1.1/genética , Conformação de Ácido Nucleico , Oligonucleotídeos Antissenso/metabolismo , Técnicas de Patch-Clamp , Fenótipo , RNA Longo não Codificante/antagonistas & inibidores , RNA Longo não Codificante/genética , Reação em Cadeia da Polimerase em Tempo Real , Alinhamento de Sequência , Análise de Sequência de RNA , Temperatura , Regulação para Cima , Células Vero , Gravação em Vídeo
7.
PLoS One ; 11(2): e0149250, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26871717

RESUMO

BACKGROUND: Palliative sedation is the widely-used intervention of administering sedating agents to induce a state of unconsciousness to take away a dying patient's perception of otherwise irrelievable symptoms. However, it remains questionable whether this ethically complex intervention is beneficial for patients and whether the associated lack of communication in the last phase of life has a negative impact on relatives' wellbeing. METHODS: An observational questionnaire study was conducted among relatives of a consecutive sample of patients who died a non-sudden death in the Erasmus MC Cancer Institute or in the hospice 'Laurens Cadenza' (both in Rotterdam) between 2010 and 2013. RESULTS: Relatives filled in questionnaires regarding 151 patients who had been sedated and 90 patients who had not been sedated. The median time since all patients had passed away was 21 (IQR 14-32) months. No significant differences were found in relatives´ assessments of the quality of end-of-life care, patients´ quality of life in the last week before death and their quality of dying, between patients who did and did not receive sedation, or in relatives' satisfaction with their own life, their general health and their mental wellbeing after the patient's death. CONCLUSIONS: The use of sedation in these patients appears to have no negative effect on bereaved relatives' evaluation of the patient's dying phase, or on their own wellbeing after the patient's death.


Assuntos
Cuidados Paliativos/métodos , Assistência Terminal/métodos , Idoso , Idoso de 80 Anos ou mais , Luto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Inquéritos e Questionários
8.
BMC Psychol ; 3: 27, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26273472

RESUMO

BACKGROUND: Mindfulness-based interventions have shown to reduce psychological distress in cancer patients. The accessibility of mindfulness-based interventions for cancer patients could be further improved by providing mindfulness using an individual internet-based format. The aim of this study is to test the effectiveness of a Mindfulness-Based Cognitive Therapy (MBCT) group intervention for cancer patients in comparison with individual internet-based MBCT and treatment as usual (TAU). METHODS/DESIGN: A three-armed multicenter randomized controlled trial comparing group-based MBCT to individual internet-based MBCT and TAU in cancer patients who suffer from at least mild psychological distress (Hospital Anxiety and Depression Scale (HADS) ≥ 11). Measurements will be conducted prior to randomization (baseline), post-treatment and at 3 months and 9 months post-treatment. Participants initially allocated to TAU are subsequently randomized to either group- or individual internet-based MBCT and will receive a second baseline measurement after 3 months. Thus, the three-armed comparison will have a time span of approximately 3 months. The two-armed intervention comparison includes a 9-month follow-up and will also consist of participants randomized to the intervention after TAU. Primary outcome will be post-treatment psychological distress (HADS). Secondary outcomes are fear of cancer recurrence (Fear of Cancer Recurrence Inventory), rumination (Rumination and Reflection Questionnaire), positive mental health (Mental Health Continuum - Short Form), and cost-effectiveness (health-related quality of life (EuroQol -5D and Short Form-12) and health care usage (Trimbos and iMTA questionnaire on Costs associated with Psychiatric illness). Potential predictors: DSM-IV-TR mood/anxiety disorders (SCID-I) and neuroticism (NEO-Five Factor Inventory) will be measured. Mediators of treatment effect: mindfulness skills, (Five-Facets of Mindfulness Questionnaire- Short Form), working alliance (Working Alliance Inventory) and group cohesion (Group Cohesion Questionnaire) will also be measured. DISCUSSION: This trial will provide valuable information on the clinical and cost-effectiveness of group versus internet-based MBCT versus TAU for distressed cancer patients. TRIAL REGISTRATION: Clinicaltrials.gov NCT02138513. Registered 6 May 2014.


Assuntos
Internet , Atenção Plena , Neoplasias/psicologia , Psicoterapia de Grupo/métodos , Estresse Psicológico/prevenção & controle , Adulto , Terapia Cognitivo-Comportamental/métodos , Análise Custo-Benefício , Humanos , Escalas de Graduação Psiquiátrica , Qualidade de Vida , Projetos de Pesquisa
9.
Nanotechnology ; 25(46): 465702, 2014 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-25354930

RESUMO

InGaAs quantum dots (QDs) on GaP are promising for monolithic integration of optoelectronics with Si technology. To understand and improve the optical properties of InGaAs/GaP QD systems, detailed measurements of the QD atomic structure as well as the spatial distributions of each element at high resolution are crucial. This is because the QD band structure, band alignment, and optical properties are determined by the atomic structure and elemental composition. Here, we directly measure the inhomogeneous distributions of In and As in InGaAs QDs grown on GaAs and GaP substrates at the nanoscale using energy dispersive x-ray spectral mapping in a scanning transmission electron microscope. We find that the In distribution is broader on GaP than on GaAs, and as a result, the QDs appear to be In-poor using a GaP matrix. Our findings challenge some of the assumptions made for the concentrations and distributions of In within InGaAs/GaAs or InGaAs/GaP QD systems and provide detailed structural and elemental information to modify the current band structure understanding. In particular, the findings of In deficiency and inhomogeneous distribution in InGaAs/GaP QD systems help to explain photoluminescence spectral differences between InGaAs/GaAs and InGaAs/GaP QD systems.

10.
Ultrasound Obstet Gynecol ; 43(4): 396-403, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23828768

RESUMO

OBJECTIVES: Conotruncal heart defects (CTD) are associated with del22q11.2 syndrome, which is often diagnosed by fluorescence in-situ hybridization (FISH). However, in those negative for del22q11.2 on FISH, the etiology is usually obscure. We aimed to use high-resolution array comparative genomic hybridization (array CGH) to clarify the underlying genetic causes in these cases. METHODS: In this retrospective study, fetal samples of amniocytes or fibroblasts, taken either for prenatal diagnosis by amniocentesis or for postnatal survey after termination of pregnancy, were obtained from 45 fetuses with CTD and were investigated by cytogenetic analysis including karyotyping and FISH for del22q11.2 syndrome. Eight fetuses with no findings on karyotyping and FISH were investigated further by array CGH, real-time quantitative polymerase chain reaction (qPCR) and Sanger sequencing of TBX1. RESULTS: Array CGH revealed that three of the eight fetuses carried submicroscopic genomic imbalances. Of these, two cases showed similar small microdeletions/duplications in 22q11.2 (one 0.85 kb microdeletion and one 8.51 kb microduplication). The minimal shared region spanned exon 2 of TBX1, a candidate gene responsible for cardiovascular defects in del22q11.2 syndrome. In all eight cases, the array CGH results were confirmed by qPCR, and Sanger sequencing did not detect other molecular pathologies. CONCLUSION: Our findings indicate an association between TBX1 variations and fetal CTD. The results also demonstrate the power of array CGH to further scrutinize the critical gene(s) of del22q11.2 syndrome responsible for heart defects. Array CGH apparently has diagnostic sensitivity superior to that of FISH in fetuses with CTD associated with del22q11.2 (and dup22q11.2) syndrome.


Assuntos
Deleção de Genes , Duplicação Gênica , Cardiopatias Congênitas/genética , Hibridização in Situ Fluorescente , Proteínas com Domínio T/genética , Amniocentese , Hibridização Genômica Comparativa , Análise Citogenética , Síndrome de DiGeorge/diagnóstico , Feminino , Fibroblastos , Cardiopatias Congênitas/diagnóstico , Humanos , Cariotipagem , Gravidez , Diagnóstico Pré-Natal , Estudos Retrospectivos
11.
J Appl Microbiol ; 115(5): 1159-71, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23879736

RESUMO

AIMS: To develop a simple gas chromatography-mass spectrometry (GC-MS) method for the detection and differentiation of Burkholderia pseudomallei and Burkholderia mallei from each other, Burkholderia thailandensis and several members of the Burkholderia cepacia complex. METHODS AND RESULTS: Biomarkers were generated by one-step thermochemolysis (TCM) and analysed using a GC-MS system. Fragments of poly-3-hydroxybutyrate-co-hydroxyvalerate [poly(3HBA-co-3HVA)] produced by TCM were useful biomarkers. Several cellular fatty acid methyl esters were important in differentiating the various Burkholderia species. A statistical discrimination algorithm was constructed using a combination of biomarkers. The identities of four B. pseudomallei strains, four B. mallei strains and one strain of each near neighbour were confirmed in a statistically designed test using the algorithm. The detection limit for this method was found to be approximately 4000 cells. CONCLUSIONS: The method is fast, accurate and easy to use. The algorithm is robust against different growth conditions (medium and temperature). SIGNIFICANCE AND IMPACT OF THE STUDY: This assay may prove beneficial in a clinical diagnostic setting, where the rapid identification of B. pseudomallei is essential to effective treatment. This method could also be easily employed after a biological attack to confirm the presence of either B. pseudomallei or B. mallei.


Assuntos
Complexo Burkholderia cepacia/classificação , Cromatografia Gasosa-Espectrometria de Massas/métodos , Algoritmos , Biomarcadores/química , Complexo Burkholderia cepacia/isolamento & purificação , Burkholderia mallei/classificação , Burkholderia mallei/isolamento & purificação , Burkholderia pseudomallei/classificação , Burkholderia pseudomallei/isolamento & purificação , Ácidos Graxos/química , Poliésteres/química
12.
Clin Microbiol Infect ; 19(8): 745-51, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23009319

RESUMO

Invasive fungal disease (IFD) shows distinct regional incidence patterns and epidemiological features depending on the geographic region. We conducted a prospective survey in eight centres in Brazil from May 2007 to July 2009. All haematopoietic cell transplant (HCT) recipients and patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS) were followed from admission until 1 year (HCT) or end of consolidation therapy (AML/MDS). The 12-month cumulative incidence (CI) of proven or probable IFD was calculated, and curves were compared using the Grey test. Among 237 AML/MDS patients and 700 HCT recipients (378 allogeneic, 322 autologous), the 1-year CI of IFD in AML/MDS, allogeneic HCT and autologous HCT was 18.7%, 11.3% and 1.9% (p <0.001), respectively. Fusariosis (23 episodes), aspergillosis (20 episodes) and candidiasis (11 episodes) were the most frequent IFD. The 1-year CI of aspergillosis and fusariosis in AML/MDS, allogeneic HCT and autologous HCT were 13.4%, 2.3% and 0% (p <0.001), and 5.2%, 3.8% and 0.6% (p 0.01), respectively. The 6-week probability of survival was 53%, and was lower in cases of fusariosis (41%). We observed a high burden of IFD and a high incidence and mortality for fusariosis in this first multicentre epidemiological study of IFD in haematological patients in Brazil.


Assuntos
Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Hospedeiro Imunocomprometido , Leucemia Mieloide Aguda/complicações , Micoses/epidemiologia , Síndromes Mielodisplásicas/complicações , Transplante , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aspergillus/isolamento & purificação , Brasil/epidemiologia , Candida/isolamento & purificação , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Fusarium/isolamento & purificação , Humanos , Incidência , Lactente , Recém-Nascido , Leucemia Mieloide Aguda/terapia , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Micoses/microbiologia , Síndromes Mielodisplásicas/terapia , Adulto Jovem
13.
Opt Express ; 21 Suppl 6: A991-6, 2013 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-24514940

RESUMO

Hydrogen generation through water splitting by n-InGaN working electrodes with bias generated from GaAs solar cell was studied. Instead of using an external bias provided by power supply, a GaAs-based solar cell was used as the driving force to increase the rate of hydrogen production. The water-splitting system was tuned using different approaches to set the operating points to the maximum power point of the GaAs solar cell. The approaches included changing the electrolytes, varying the light intensity, and introducing the immersed ITO ohmic contacts on the working electrodes. As a result, the hybrid system comprising both InGaN-based working electrodes and GaAs solar cells operating under concentrated illumination could possibly facilitate efficient water splitting.

14.
Opt Express ; 20 Suppl 5: A678-83, 2012 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-23037534

RESUMO

Hydrogen generation through direct photoelectrolysis of water was studied using photoelectrochemical (PEC) cells made of Mn-doped GaN photoelectrodes. In addition to its absorption of the ultraviolet spectrum, Mn-doped GaN photoelectrodes could absorb photons in the visible spectrum. The photocurrents measured from PEC cells made of Mn-doped GaN were at least one order higher than those measured from PEC cells made of undoped GaN-working electrodes. Under the visible light illumination and a bias voltage below 1.2 V, the Mn-doped GaN photoelectrodes could drive the water splitting reaction for hydrogen generation. However, hydrogen generation could not be achieved under the same condition wherein undoped GaN photoelectrodes were used. According to the results of the spectral responses and transmission spectra obtained from the experimental photoelectrodes, the enhanced photocurrent in the Mn-doped GaN photoelectrodes, compared with the undoped GaN photoelectrodes, was attributable to the Mn-related intermediate band within the band gap of GaN that resulted in further photon absorption.

15.
Opt Express ; 20 Suppl 2: A190-6, 2012 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-22418667

RESUMO

In this study, we demonstrated photoelectrochemical (PEC) hydrogen generation using p-GaN photoelectrodes associated with immersed finger-type indium tin oxide (IF-ITO) ohmic contacts. The IF-ITO/p-GaN photoelectrode scheme exhibits higher photocurrent and gas generation rate compared with p-GaN photoelectrodes without IF-ITO ohmic contacts. In addition, the critical external bias for detectable hydrogen generation can be effectively reduced by the use of IF-ITO ohmic contacts. This finding can be attributed to the greatly uniform distribution of the IF-ITO/p-GaN photoelectrode applied fields over the whole working area. As a result, the collection efficiency of photo-generated holes by electrode contacts is higher than that of p-GaN photoelectrodes without IF-ITO contacts. Microscopy revealed a tiny change on the p-GaN surfaces before and after hydrogen generation. In contrast, photoelectrodes composed of n-GaN have a short lifetime due to n-GaN corrosion during hydrogen generation. Findings of this study indicate that the ITO finger contacts on p-GaN layer is a potential candidate as photoelectrodes for PEC hydrogen generation.

16.
Artigo em Inglês | MEDLINE | ID: mdl-22454675

RESUMO

Lignosus rhinocerus, the tiger milk mushroom, is one of the most important medicinal mushrooms used by the indigenous people of Southeast Asia and China. It has been used to treat breast cancer. A cold water extract (LR-CW) prepared from the sclerotia of L. rhinocerus cultivar was found to exhibit antiproliferative activity against human breast carcinoma (MCF-7) and human lung carcinoma (A549), with IC(50) of 96.7 µg/mL and 466.7 µg/mL, respectively. In comparison, LR-CW did not show significant cytotoxicity against the two corresponding human normal cells, 184B5 (human breast cell) and NL 20 (human lung cell). DNA fragmentation studies suggested that the cytotoxic action of LR-CW against cancer cells is mediated by apoptosis. Sephadex G-50 gel filtration fractionation of LR-CW yielded a high-molecular-weight and a low-molecular-weight fraction. The high-molecular-weight fraction contains mainly carbohydrate (68.7%) and small amount of protein (3.6%), whereas the low-molecular-weight fraction contains 31% carbohydrate and was devoid of protein. Only the high-molecular-weight fraction exhibited antiproliferative activity against cancer cells, with IC(50) of 70.0 µg/mL and 76.7 µg/mL, respectively. Thus, the cytotoxic action of the LR-CW is due to the high-molecular-weight fraction, either the proteins or protein-carbohydrate complex.

17.
Opt Express ; 19 Suppl 6: A1196-201, 2011 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-22109615

RESUMO

An n-GaN photoelectrochemical (PEC) cell with immersed finger-type indium tin oxide (ITO) ohmic contacts was demonstrated in the present study to enhance the hydrogen generation rate. The finger-type ITO ohmic contacts were covered with SiO2 layers to prevent the PEC cell from generating leakage current. Using a 1M NaCl electrolyte and external biases, the typical photocurrent density and gas generation rate of the n-GaN working electrodes with ITO finger contacts were found to be higher than those with Cr/Au finger contacts. The enhancement in photocurrent density or gas generation rate can be attributed to the transparent ITO contacts which allowed the introduction of relatively more photons into the GaN layer. No significant corrosion was observed in the ITO layer after the PEC process compared with the Cr/Au finger contacts which were significantly peeled from the GaN layer. These results indicate that the use of n-GaN working electrodes with finger-type ITO ohmic contacts is a promising approach for PEC cells.

18.
ISRN Endocrinol ; 2011: 696124, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22363885

RESUMO

Objective. This study compares low dose versus aggressive inhibition of the renin angiotensin system (RAS) to treat microalbuminuria (MA). Methods. Patients with MA after a run-in period to control BP to <130/80 mm Hg with 10 mg benazepril plus other drugs and HbA1c levels to <8.0% were randomized to either continue 10 mg benazepril (N = 12) or to take maximal doses of benazepril plus losartan in monthly stepwise increases to achieve normoalbuminuria (N = 11). Because MA is associated with CVD and inflammation, carotid intima medial thickness (CIMT) and endothelial function by peripheral arterial tonometry (PAT) as surrogate indices of atherosclerosis and highly sensitive C-reactive protein (hs-CRP) to assess inflammation were measured every six months. Results. BP, HbA1c levels, albumin : creatinine ratios, CIMT, PAT, and hs-CRP did not differ over a mean of 12 months between the two groups. Conclusions. Aggressive inhibition of the RAS is unnecessary to treat MA.

19.
Horm Metab Res ; 42(12): 874-81, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20803415

RESUMO

Many Endocrinologists believe that a single determination of eucortisolism or a single demonstration of appropriate suppression to dexamethasone excluded Cushing's syndrome, except in what was previously thought to be the rare patient with episodic or periodic Cushing's syndrome. We hypothesize that episodic Cushing's syndrome is relatively common and a single test assessing hypercortisolism may not be sufficient to accurately rule out or diagnose Cushing's syndrome and retrospectively examined the number of normal and abnormal tests assessing hypercortisolism performed on multiple occasions in 66 patients found to have mild and/or episodic Cushing's syndrome compared to a similar group of 54 patients evaluated for, but determined not to have Cushing's syndrome. We found that 65 of the 66 patients with Cushing's syndrome had at least one normal test of cortisol status and most patients had several normal tests. The probability of having Cushing's syndrome when one test was negative was 92% for 23:00 h salivary cortisol, 88% for 24-h UFC, 86% for 24-h 17OHS, and 54% for nighttime plasma cortisol. These results demonstrated that episodic hypercortisolism is highly prevalent in subjects with mild Cushing's syndrome and no single test was effective in conclusively diagnosing or excluding the condition. Rather, the paradigm for the diagnosis should be a careful history and physical examination and in those patients in whom mild Cushing's syndrome/disease is strongly suspected, multiple tests assessing hypercortisolism should be performed on subsequent occasions, especially when the patient is experiencing signs and symptoms of short-term hypercortisolism.


Assuntos
Síndrome de Cushing/diagnóstico , Hidrocortisona/análise , Adolescente , Hiperfunção Adrenocortical , Adulto , Síndrome de Cushing/sangue , Síndrome de Cushing/metabolismo , Síndrome de Cushing/urina , Feminino , Humanos , Hidrocortisona/sangue , Hidrocortisona/urina , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Retrospectivos , Saliva/química , Saliva/metabolismo , Adulto Jovem
20.
Singapore Med J ; 51(7): 599-607, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20730402

RESUMO

The Academy of Medicine, Singapore (AMS) and the Ministry of Health (MOH) publish clinical practice guidelines to provide doctors and patients in Singapore with evidence-based guidance on managing important medical conditions. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the AMS-MOH clinical practice guidelines on the Management of Food Allergy, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Academy of Medicine website: http://www.ams.edu.sg/guidelines.asp#foodallergy. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.


Assuntos
Academias e Institutos/normas , Hipersensibilidade Alimentar/terapia , Guias de Prática Clínica como Assunto , Adolescente , Adulto , Criança , Pré-Escolar , Medicina Baseada em Evidências , Feminino , Política de Saúde , Humanos , Masculino , Singapura
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