RESUMO
Cytochrome c oxidase deficiency (COXD) is an inherited disorder characterized by the absence or mutation in the genes encoding for the cytochrome c oxidase protein (COX). COX deficiency results in severe muscle weakness, heart, liver, and kidney disorders, as well as brain damage in infants and adolescents, leading to death in many cases. With no cure for this disorder, finding an efficient, inexpensive, and early means of diagnosis is essential to minimize symptoms and long-term disabilities. Furthermore, muscle biopsy, the traditional detection method, is invasive, expensive, and time-consuming. This study demonstrates the applicability of scanning electrochemical microscopy to quantify COX activity in living human fibroblast cells. Taking advantage of the interaction between the redox mediator N, N, N', N'-tetramethyl-para-phenylene-diamine, and COX, the enzymatic activity was successfully quantified by monitoring current changes using a platinum microelectrode and determining the apparent heterogeneous rate constant k0 using numerical modeling. This study provides a foundation for developing a diagnostic method for detecting COXD in infants, which has the potential to increase treatment effectiveness and improve the quality of life of affected individuals.
Assuntos
Deficiência de Citocromo-c Oxidase , Lactente , Humanos , Adolescente , Deficiência de Citocromo-c Oxidase/genética , Microscopia Eletroquímica de Varredura , Qualidade de Vida , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Fibroblastos/metabolismoRESUMO
Scanning electrochemical microscopy (SECM) is being used increasingly to monitor electrochemical processes at the interface of living cells and electrodes. This allows the detection and quantification of biomarkers that further the understanding of various diseases. Rapid SECM experiments are often carried out without monitoring the analyte solution temperature or are performed at room temperature. The reported research demonstrates that temperature control is crucial during SECM imaging of living cells to obtain reliable data. In this study, a SECM-integrated thermostatic ring on the sample stage enabled imaging of living biological cells in a constant height mode at various temperatures. Two-dimensional line scans were conducted while scanning single Adenocarcinoma Cervical cancer (HeLa) cells. Numerical modeling was carried out to evaluate the effect of the temperature on the electrochemical current response of living cells to compare the apparent heterogeneous rate constant (k0), representing cellular reaction kinetics. This study reveals that even slight temperature variations of approximately 2 °C affect the reaction kinetics of single living cells, altering the measured current during SECM.
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Diagnóstico por Imagem , Humanos , Microscopia Eletroquímica de Varredura , Temperatura , Eletrodos , Células HeLaRESUMO
BACKGROUND: An endotracheal tube cuff pressure between 20 and 30 cmH2O is recommended to prevent ventilator-associated respiratory infection (VARI). We aimed to evaluate whether continuous cuff pressure control (CPC) was associated with reduced VARI incidence compared with intermittent CPC. METHODS: We conducted a multicenter open-label randomized controlled trial in intensive care unit (ICU) patients within 24 hours of intubation in Vietnam. Patients were randomly assigned 1:1 to receive either continuous CPC using an automated electronic device or intermittent CPC using a manually hand-held manometer. The primary endpoint was the occurrence of VARI, evaluated by an independent reviewer blinded to the CPC allocation. RESULTS: We randomized 600 patients; 597 received the intervention or control and were included in the intention to treat analysis. Compared with intermittent CPC, continuous CPC did not reduce the proportion of patients with at least one episode of VARI (74/296 [25%] vs 69/301 [23%]; odds ratio [OR] 1.13; 95% confidence interval [CI] .77-1.67]. There were no significant differences between continuous and intermittent CPC concerning the proportion of microbiologically confirmed VARI (OR 1.40; 95% CI .94-2.10), the proportion of intubated days without antimicrobials (relative proportion [RP] 0.99; 95% CI .87-1.12), rate of ICU discharge (cause-specific hazard ratio [HR] 0.95; 95% CI .78-1.16), cost of ICU stay (difference in transformed mean [DTM] 0.02; 95% CI -.05 to .08], cost of ICU antimicrobials (DTM 0.02; 95% CI -.25 to .28), cost of hospital stay (DTM 0.02; 95% CI -.04 to .08), and ICU mortality risk (OR 0.96; 95% CI .67-1.38). CONCLUSIONS: Maintaining CPC through an automated electronic device did not reduce VARI incidence. CLINICAL TRIAL REGISTRATION: NCT02966392.
Assuntos
Pneumonia Associada à Ventilação Mecânica , Infecções Respiratórias , Humanos , Intubação Intratraqueal/efeitos adversos , Tempo de Internação , Pneumonia Associada à Ventilação Mecânica/epidemiologia , Pneumonia Associada à Ventilação Mecânica/microbiologia , Pneumonia Associada à Ventilação Mecânica/prevenção & controle , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/prevenção & controle , Ventiladores MecânicosRESUMO
BACKGROUND: Bloodstream infections (BSIs) are associated with high morbidity and mortality worldwide. However their aetiology, antimicrobial susceptibilities and associated outcomes differ between developed and developing countries. Systematic data from Vietnam are scarce. Here we present aetiologic data on BSI in adults admitted to a large tertiary referral hospital for infectious diseases in Hanoi, Vietnam. METHODS: A retrospective study was conducted at the National Hospital for Tropical Diseases between January 2011 and December 2013. Cases of BSI were determined from records in the microbiology department. Case records were obtained where possible and clinical findings, treatment and outcome were recorded. BSI were classified as community acquired if the blood sample was drawn ≤48 h after hospitalization or hospital acquired if >48 h. RESULTS: A total of 738 patients with BSI were included for microbiological analysis. The predominant pathogens were: Klebsiella pneumoniae (17.5%), Escherichia coli (17.3%), Staphylococcus aureus (14.9%), Stenotrophomonas maltophilia (9.6%) and Streptococcus suis (7.6%). The overall proportion of extended spectrum beta-lactamase (ESBL) production among Enterobacteriaceae was 25.1% (67/267 isolates) and of methicillin-resistance in S. aureus (MRSA) 37% (40/108). Clinical data was retrieved for 477 (64.6%) patients; median age was 48 years (IQR 36-60) with 27.7% female. The overall case fatality rate was 28.9% and the highest case fatality was associated with Enterobacteriaceae BSI (34.7%) which accounted for 61.6% of all BSI fatalities. CONCLUSIONS: Enterobacteriaceae (predominantly K. pneumoniae and E. coli) are the most common cause of both community and hospital acquired bloodstream infections in a tertiary referral clinic in northern Vietnam.
Assuntos
Bacteriemia/tratamento farmacológico , Bacteriemia/microbiologia , Farmacorresistência Bacteriana , Adulto , Bacteriemia/epidemiologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/patogenicidade , Feminino , Humanos , Klebsiella pneumoniae/isolamento & purificação , Klebsiella pneumoniae/patogenicidade , Masculino , Pessoa de Meia-Idade , Mortalidade , Estudos Retrospectivos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/patogenicidade , Centros de Atenção Terciária , Resultado do Tratamento , Vietnã/epidemiologia , beta-Lactamases/genéticaRESUMO
Scanning electrochemical microscopy (SECM) is increasingly applied to study and image live cells. Quantitative analyses of biological systems, however, still remain challenging. In the presented study, single human adenocarcinoma cervical cancer cells are electrochemically investigated by means of SECM. The target cell's electrochemical response is observed over time under the influence of green tea catechins (GTC), which are suggested to offer chemopreventive and therapeutic effects on cancer. The electrochemical response of living target cells is measured experimentally and quantified in an apparent heterogeneous rate constant by using a numerical model, based on forced convection during high speed SECM imaging. The beneficial effect of GTC on cancer cells could be confirmed by SECM, and the presented study shows an alternative approach toward unraveling the mechanisms involved during inhibition of carcinogenesis.
Assuntos
Catequina/química , Técnicas de Química Analítica/métodos , Eletroquímica , Microscopia Eletroquímica de Varredura , Neoplasias/patologia , Carcinogênese/efeitos dos fármacos , Catequina/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células HeLa , Humanos , Cinética , Chá/químicaRESUMO
Scanning electrochemical microscopy (SECM) allows imaging and analysis of a variety of biological samples, such as living cells. Up to now, it still remains a challenge to successfully decouple signals related to topography and reactivity. Furthermore, such delicate samples require careful adjustment of experimental parameters, such as scan velocity. The present study proposes a method to extract a substrate's kinetic rate by numerical modeling and experimental high speed constant height SECM imaging. This is especially useful for the determination of substrates with unknown surface reaction kinetics and large topographical features. To make this approach applicable to soft cell samples, which cannot be imaged at high velocity, a nonlinear fit strategy is presented to obtain kinetic rate values also under slow scan velocity conditions.
Assuntos
Técnicas de Química Analítica/métodos , Microscopia Eletroquímica de Varredura , Polímeros/química , Eletrodos , Cinética , Platina/químicaRESUMO
Rhodococcus equi infection is increasing in regions with high HIV prevalence worldwide. The microbiological features and clinical mimicry of tuberculosis infection pose diagnostic challenges in high-tuberculosis-incidence settings. We present two HIV-associated cases of R. equi infection from Vietnam and discuss the unique diagnostic challenges in such settings.
Assuntos
Infecções por Actinomycetales/diagnóstico , Rhodococcus equi , Tuberculose Pulmonar/diagnóstico , Infecções por Actinomycetales/complicações , Infecções por Actinomycetales/epidemiologia , Infecções por Actinomycetales/microbiologia , Adulto , Antibacterianos/uso terapêutico , Fármacos Anti-HIV/uso terapêutico , Ácido Ascórbico , Colecalciferol , Desidroepiandrosterona/análogos & derivados , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Humanos , Masculino , Ácidos Nicotínicos , Extratos Vegetais , Tuberculose Pulmonar/complicações , Tuberculose Pulmonar/epidemiologia , Vietnã/epidemiologiaRESUMO
The effect of the insulator-mixed-material edge on the galvanic corrosion rate of magnesium alloy (AE44)-mild steel (MS) couple is experimentally studied using scanning vibrating electrode technique (SVET), profilometry, and classical electrochemistry. The local and average corrosion rates estimated from the experimental depth of anodic attack profile of AE44-MS couple are validated by 2D and 3D corrosion numerical models. Our study demonstrates experimentally and theoretically that the presence of the insulator edge increases the local current density, which enhances the corrosion rate. The extent of the local corrosion rate enhancement and its effect on the overall corrosion rate of the mixed material is discussed and depends on the mixed material's geometry and the edge type.
RESUMO
Microelectrodes as analytical sensing tools have gained immense popularity in a wide range of applications, ranging from probe design advancement to single live cell imaging. Micro-optical-ring electrodes (MOREs) are micro-scale ring-electrodes with an optical fiber core, that enables the MORE to conduct an optical signal while performing electrochemistry. Herein, we present a user-friendly and cost-effective method to fabricate MOREs for scanning photoelectrochemical microscopy (SPECM) applications. MOREs were characterized by electrochemistry, numerical modelling, and scanning electron microscopy (SEM), ensuring reproducibility in terms of a well-defined geometry and functionality. In this study, the integration of MOREs into scanning probe microscopy enabled the spectro-electrochemical detection of N, N, N, N'- Tetramethyl-p-phenyl-enediamine (TMPD) and its oxidized radical cation counterpart. UV-VIS spectroscopy capabilities of MOREs were optimized through tip-to-substrate distance variations. To demonstrate the applicability of MOREs to electrochemical single live cell imaging, oxygen production was detected in living algae (Eremosphaera viridis) by local illumination and concurrent electrochemical measurements.
Assuntos
Técnicas Biossensoriais , Microscopia , Técnicas Biossensoriais/métodos , Eletrodos , Microeletrodos , Microscopia Eletrônica de Varredura , Oxigênio , Reprodutibilidade dos TestesRESUMO
The development of the scanning electrochemical microscope in ac mode is presented from both experimental and theoretical point of views. The experiments are performed with the ferri/ferrocyanide redox mediator as model system. Based on analysis of the frequency-dependent collection efficiency, diffusion between the probe and the substrate is investigated, and analysis of time constants allows evaluation of the size of the sensing area under investigation. The experimental results are in good agreement with numerical simulations.
RESUMO
A scanning electrochemical microscope (SECM) in ac mode is used for the characterisation of the adsorption process during the hydrogen evolution reaction (HER) in sulfuric acid solution. It is shown that this technique allows quantitative analysis of the adsorption process, and measurements of the differential capacitance with the frequency as parameter are obtained. The time constant for relaxation of adsorbed hydrogen (H(ads)) is approximately 2 Hz, and analysis of the Nyquist plot allows direct evaluation of the charge involved. In addition, the direct comparison of the usual electrochemical impedance data and ac-SECM results obtained simultaneously permits characterisation of processes occurring at the surface and in solution.
RESUMO
PROBLEM: Streptococcus suis is a common cause of adult bacterial meningitis in Viet Nam, and possibly other parts of Asia, yet this disabling infection has been largely neglected. Prevention, diagnosis and treatment are relatively straightforward and affordable but, in early 2007, no national diagnostic, case management or prevention guidelines existed in Viet Nam. APPROACH: Enhanced detection of S. suis infections was established in 2007 as part of a collaborative research programme between the National Hospital for Tropical Diseases, a key national hospital with very close links to the Ministry of Health, and a research group affiliated with Oxford University based in Viet Nam. The results were reported directly to policy-makers at the Ministry of Health. LOCAL SETTING: Viet Nam is a low-income country with a health-care system that has seen considerable improvements and increased autonomy. However, parts of the system remain fairly centralized the Ministry of Health. RELEVANT CHANGES: Following the improved detection and reporting of S. suis cases, the Ministry of Health issued guidance to all hospitals in Viet Nam on the clinical and laboratory diagnosis, treatment and prevention of S. suis. A public health laboratory diagnostic service was established at the National Institute of Hygiene and Epidemiology and training courses were conducted for clinicians and microbiologists. Ministry of Health guidance on surveillance and control of communicable diseases was updated to include a section on S. suis. LESSONS LEARNT: Research collaborations can efficiently inform and influence national responses if they are well positioned to reach policy-makers.
Assuntos
Comportamento Cooperativo , Política de Saúde , Meningites Bacterianas/diagnóstico , Guias de Prática Clínica como Assunto , Infecções Estreptocócicas/diagnóstico , Streptococcus suis/isolamento & purificação , Humanos , Meningites Bacterianas/tratamento farmacológico , Meningites Bacterianas/epidemiologia , Meningites Bacterianas/microbiologia , Vigilância da População , Qualidade da Assistência à Saúde , Fatores de Risco , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/epidemiologia , VietnãRESUMO
Scanning electrochemical microscopy (SECM) is a powerful technique for performing quantitative measurements at a local scale. This paper covers the development of combinations of SECM with electrochemical impedance spectroscopy (EIS) and electrochemical quartz crystal microbalance (EQCM). Basic aspects are described and potential applications reported by several research groups are covered. The unique advantages of the coupled techniques--with additional information being obtained from each coupling--are also discussed.
RESUMO
OBJECTIVES: We assessed the impact of MALDITOF-MS on the timeliness of optimal antimicrobial therapy through a parallel-arm randomised controlled trial in two hospitals in Vietnam. METHODS: We recruited patients with a pathogen (bacterial or fungal) cultured from a normally sterile sample. Samples were randomly assigned (1:1) to identification by MALDITOF-MS or conventional diagnostics. The primary outcome was the proportion on optimal antimicrobial therapy within 24â¯h of positive culture, determined by a blinded independent review committee. Trial registered at ClinicalTrials.gov (NCT02306330). RESULTS: Among 1005 randomised patients, pathogens were isolated from 628 (326 intervention, 302 control), with 377 excluded as likely contaminants or discharged/died before positive culture. Most isolates were cultured from blood (421/628, 67.0%). The proportion receiving optimal antimicrobial therapy within 24â¯h (the primary outcome) or 48â¯h of growth was not significantly different between MALDITOF-MS and control arms (135/326, 41.4%â¯vs 120/302, 39.7%; Adjusted Odds ration (AOR) 1.17, pâ¯=â¯0.40 and 151/326, 46.3%â¯vs 141/302, 46.7%; AOR 1.05 pâ¯=â¯0.79, respectively). CONCLUSIONS: MALDITOF-MS, in the absence of an antimicrobial stewardship programme, did not improve the proportion on optimal antimicrobial therapy at 24 or 48â¯h after first growth in a lower-middle income setting with high rates of antibiotic resistance.
Assuntos
Bacteriemia/tratamento farmacológico , Bactérias/isolamento & purificação , Fungos/isolamento & purificação , Técnicas Microbiológicas , Micoses/tratamento farmacológico , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Adulto , Antibacterianos/uso terapêutico , Antifúngicos/uso terapêutico , Bacteriemia/diagnóstico , Bacteriemia/microbiologia , Bactérias/efeitos dos fármacos , Feminino , Fungos/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Micoses/diagnóstico , Micoses/microbiologia , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento , VietnãAssuntos
Coinfecção/veterinária , Surtos de Doenças , Síndrome Respiratória e Reprodutiva Suína/epidemiologia , Infecções Estreptocócicas/veterinária , Streptococcus suis/genética , Animais , Antibacterianos/farmacologia , Coinfecção/diagnóstico , Coinfecção/epidemiologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Humanos , Técnicas de Diagnóstico Molecular , Reação em Cadeia da Polimerase , Síndrome Respiratória e Reprodutiva Suína/diagnóstico , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Infecções Estreptocócicas/diagnóstico , Infecções Estreptocócicas/epidemiologia , Streptococcus suis/efeitos dos fármacos , Streptococcus suis/isolamento & purificação , Sus scrofa , Suínos , Vietnã/epidemiologiaRESUMO
BACKGROUND: Ventilator-associated respiratory infection (VARI) comprises ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT). Although their diagnostic criteria vary, together these are the most common hospital-acquired infections in intensive care units (ICUs) worldwide, responsible for a large proportion of antibiotic use within ICUs. Evidence-based strategies for the prevention of VARI in resource-limited settings are lacking. Preventing the leakage of oropharyngeal secretions into the lung using continuous endotracheal cuff pressure control is a promising strategy. The aim of this study is to investigate the efficacy of automated, continuous endotracheal cuff pressure control in preventing the development of VARI and reducing antibiotic use in ICUs in Vietnam. METHODS/DESIGN: This is an open-label randomised controlled multicentre trial. We will enrol 600 adult patients intubated for ≤ 24 h at the time of enrolment. Eligible patients will be stratified according to admission diagnosis (180 tetanus, 420 non-tetanus) and site and will be randomised in a 1:1 ratio to receive either (1) automated, continuous control of endotracheal cuff pressure or (2) intermittent measurement and control of endotracheal cuff pressure using a manual cuff pressure meter. The primary outcome is the occurrence of VARI, defined as either VAP or VAT during the ICU admission up to a maximum of 90 days after randomisation. Patients in both groups who are at risk for VARI will receive a standardised battery of investigations if their treating physician feels a new infection has occurred, the results of which will be used by an endpoint review committee, blinded to the allocated arm and independent of patient care, to determine the primary outcome. All enrolled patients will be followed for mortality and endotracheal tube cuff-related complications at 28 days and 90 days after randomisation. Other secondary outcomes include antibiotic use; days ventilated, in ICU and in hospital; inpatient mortality; costs of antibiotics in ICU; duration of ICU stay; and duration of hospital stay. DISCUSSION: This study will provide high-quality evidence concerning the use of continuous endotracheal cuff pressure control as a method to reduce VARI, antibiotic use and hospitalisation costs and to shorten stay. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02966392 . Registered on November 9, 2016. Protocol version: 2.0; issue date March 3, 2017.
Assuntos
Bronquite/prevenção & controle , Intubação Intratraqueal/efeitos adversos , Pneumonia Associada à Ventilação Mecânica/prevenção & controle , Respiração Artificial/efeitos adversos , Traqueíte/prevenção & controle , Ventiladores Mecânicos/efeitos adversos , Antibacterianos/uso terapêutico , Bronquite/diagnóstico , Bronquite/etiologia , Bronquite/mortalidade , Desenho de Equipamento , Mortalidade Hospitalar , Humanos , Intubação Intratraqueal/instrumentação , Intubação Intratraqueal/mortalidade , Tempo de Internação , Estudos Multicêntricos como Assunto , Pneumonia Associada à Ventilação Mecânica/diagnóstico , Pneumonia Associada à Ventilação Mecânica/etiologia , Pneumonia Associada à Ventilação Mecânica/mortalidade , Ensaios Clínicos Controlados Aleatórios como Assunto , Respiração Artificial/instrumentação , Respiração Artificial/mortalidade , Fatores de Risco , Fatores de Tempo , Traqueíte/diagnóstico , Traqueíte/etiologia , Traqueíte/mortalidade , Resultado do Tratamento , VietnãRESUMO
BACKGROUND: Ventilator-associated respiratory infection (VARI) is a significant problem in resource-restricted intensive care units (ICUs), but differences in casemix and etiology means VARI in resource-restricted ICUs may be different from that found in resource-rich units. Data from these settings are vital to plan preventative interventions and assess their cost-effectiveness, but few are available. METHODS: We conducted a prospective observational study in four Vietnamese ICUs to assess the incidence and impact of VARI. Patients ≥ 16 years old and expected to be mechanically ventilated > 48 h were enrolled in the study and followed daily for 28 days following ICU admission. RESULTS: Four hundred fifty eligible patients were enrolled over 24 months, and after exclusions, 374 patients' data were analyzed. A total of 92/374 cases of VARI (21.7/1000 ventilator days) were diagnosed; 37 (9.9%) of these met ventilator-associated pneumonia (VAP) criteria (8.7/1000 ventilator days). Patients with any VARI, VAP, or VARI without VAP experienced increased hospital and ICU stay, ICU cost, and antibiotic use (p < 0.01 for all). This was also true for all VARI (p < 0.01 for all) with/without tetanus. There was no increased risk of in-hospital death in patients with VARI compared to those without (VAP HR 1.58, 95% CI 0.75-3.33, p = 0.23; VARI without VAP HR 0.40, 95% CI 0.14-1.17, p = 0.09). In patients with positive endotracheal aspirate cultures, most VARI was caused by Gram-negative organisms; the most frequent were Acinetobacter baumannii (32/73, 43.8%) Klebsiella pneumoniae (26/73, 35.6%), and Pseudomonas aeruginosa (24/73, 32.9%). 40/68 (58.8%) patients with positive cultures for these had carbapenem-resistant isolates. Patients with carbapenem-resistant VARI had significantly greater ICU costs than patients with carbapenem-susceptible isolates (6053 USD (IQR 3806-7824) vs 3131 USD (IQR 2108-7551), p = 0.04) and after correction for adequacy of initial antibiotics and APACHE II score, showed a trend towards increased risk of in-hospital death (HR 2.82, 95% CI 0.75-6.75, p = 0.15). CONCLUSIONS: VARI in a resource-restricted setting has limited impact on mortality, but shows significant association with increased patient costs, length of stay, and antibiotic use, particularly when caused by carbapenem-resistant bacteria. Evidence-based interventions to reduce VARI in these settings are urgently needed.