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1.
Clin Lab ; 68(10)2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-36250840

RESUMO

BACKGROUND: In this retrospective study, we aimed to compare the laboratory and clinical results of cytokine hem-adsorption as an immunomodulation therapy in COVID-19 ICU patients with or without sepsis. METHODS: The levels of PCT, CRP, and ferritin were determined as indicators of infection/sepsis; the levels of in-terleukins (IL-6, IL-8 and IL-10, and TNF-α) were determined as indicators of cytokine storm were compared. APACHE score, SOFA score, and mortality rates were compared for the progression of the disease in 23 COVID-19 patients. RESULTS: The therapy was generally successful in reducing the levels of IL-6, IL-8, IL-10, and TNF-α but the levels measured after the procedure did not differ among the patients with or without sepsis, suggesting that the presence of sepsis did not affect the efficacy and function of the cytokine hemadsorption procedure in COVID-19 patients. All parameters were reduced after the procedure except the levels of PCT and ferritin and mortality rates of patients diagnosed with sepsis. The level of PCT was significantly higher in these patients compared with the patients without sepsis while the ferritin and mortality did not show any significant difference between the two groups, suggesting that the cytokine hemadsorption may be safe in the treatment of critical COVID-19 patients. CONCLUSIONS: As a result, the progression of sepsis in COVID-19 may be avoided with cytokine hemadsorption applied as an immunomodulator therapy. However, this therapy should be further explored and validated prior to its introduction to everyday clinical practice when the epidemic conditions end.


Assuntos
COVID-19 , Sepse , Citocinas , Ferritinas , Hemadsorção , Humanos , Fatores Imunológicos/uso terapêutico , Interleucina-10 , Interleucina-6 , Interleucina-8 , Prognóstico , Curva ROC , Estudos Retrospectivos , Sepse/diagnóstico , Sepse/tratamento farmacológico , Fator de Necrose Tumoral alfa
2.
Cureus ; 14(2): e22325, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35317038

RESUMO

Objective In this study, we aimed to analyze the laboratory and clinical results of cytokine hemadsorption as an immunomodulation therapy in ICU patients diagnosed with sepsis or septic shock. Methods The levels of procalcitonin (PCT) and C-reactive protein (CRP), determined to be indicators of infection/sepsis, and the levels of interleukins (IL-6, IL-8, and IL-10) and tumor necrosis factor α (TNFα), deemed as indicators of the cytokine storm, were compared among 32 patients before and after the hemadsorption procedure. Results The hemadsorption significantly reduced the levels of IL-6, IL-8, IL-10, TNFα, PCT, CRP, Acute Physiology and Chronic Health Evaluation (APACHE) scores, mortality rate, and Sequential Organ Failure Assessment (SOFA) scores (p<0.05). APACHE scores and the mean predicted mortality rate (PMR) of the non-survivors measured before the procedure was significantly higher than those of survivors (p=0.002 for both). IL-10, APACHE scores, and the mortality rates determined before the hemadsorption procedure were deemed significant parameters to predict the mortality among all ICU patients (p<0.05). IL-10 levels ≤125.3 ng/L, APACHE score >30, and PMR >70.33 were significantly associated with the mortality rates of all patients, indicating that these three parameters determined before the hemadsorption may be good predictors of mortality among ICU patients with sepsis. Conclusion The progression of sepsis in ICU patients may be prevented with cytokine hemadsorption applied as an immunomodulator therapy.

3.
Turk Neurosurg ; 20(1): 73-6, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20066627

RESUMO

OBJECTIVE: The authors present the case of a dumbbell-shaped schwannoma of the upper cervical spine involving the ventral rami of C-2 sensory root and rising through the foramen magnum up to the pontobulbar junction. The 27-year-old male patient complaining of hoarseness, imbalance and experiencing cervical pain and cervical muscle contractions for 2 months was admitted to the hospital. The cervical T1 and T2- weighted magnetic resonance (MR) images revealed the presence of a slightly hyperintense left C1-2 intra-extradural lesion which had eroded the clivus and odontoid process and enlarged the intervertebral foramen and was rising up to ponto-bulbar junction. A posterior approach was used to perform a suboccipital craniectomy and C1- 2 laminectomy, including opening of the dura mater and gross-total removal of the lesion. The cerebrospinal MR image of the patient obtained at the early post-operative period revealed total removal of the lesion. The patient had hypoglossal nerve palsy and mild hemiparesis on the left side which had regressed almost totally at the 3-month follow-up. The far-lateral approach with the patient in the sitting position is very important and facilitates the total removal of the schwannoma. Simple suboccipital craniectomy provided enough exposure for total removal in this case.


Assuntos
Neoplasias de Cabeça e Pescoço/cirurgia , Nervo Hipoglosso/cirurgia , Neurilemoma/cirurgia , Adulto , Calcinose/etiologia , Calcinose/patologia , Calcinose/cirurgia , Humanos , Doenças do Nervo Hipoglosso/etiologia , Doenças do Nervo Hipoglosso/cirurgia , Imageamento por Ressonância Magnética , Masculino , Crânio/cirurgia , Resultado do Tratamento
4.
Bioresour Technol ; 100(20): 4579-87, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19525108

RESUMO

A conceptual neural fuzzy model based on adaptive-network based fuzzy inference system, ANFIS, was proposed using available input on-line and off-line operational variables for a sugar factory anaerobic wastewater treatment plant operating under unsteady state to estimate the effluent chemical oxygen demand, COD. The predictive power of the developed model was improved as a new approach by adding the phase vector and the recent values of COD up to 5-10 days, longer than overall retention time of wastewater in the system. History of last 10 days for COD effluent with two-valued phase vector in the input variable matrix including all parameters had more predictive power. History of 7 days with two-valued phase vector in the matrix comprised of only on-line variables yielded fairly well estimations. The developed ANFIS model with phase vector and history extension has been able to adequately represent the behavior of the treatment system.


Assuntos
Lógica Fuzzy , Modelos Teóricos , Redes Neurais de Computação , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Anaerobiose , Reprodutibilidade dos Testes
5.
Heart Vessels ; 24(1): 70-2, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19165573

RESUMO

Although transaortic septal myectomy in obstructive hypertrophic cardiomyopathy (OHC) is accepted as a safe procedure, it may end up with serious peroperative complications. We developed a practical method to avoid this unfavorable outcome by using a 20-cc syringe body. We believe this apparatus will provide safe and effective septal myectomy procedures without additional cost.


Assuntos
Procedimentos Cirúrgicos Cardíacos/instrumentação , Cardiomiopatia Hipertrófica/cirurgia , Septos Cardíacos/cirurgia , Complicações Intraoperatórias/prevenção & controle , Desenho de Equipamento , Humanos , Resultado do Tratamento
6.
Anadolu Kardiyol Derg ; 8(5): 368-73, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18849230

RESUMO

OBJECTIVE: Postoperative respiratory functions, arterial blood gases, blood loss and clinical outcome following coronary artery bypass surgery (CABG) were assessed in a prospective randomized single-blind (patient- blind) clinical study comparing two different techniques of internal thoracic artery (ITA) harvesting. METHODS: Fifty-four patients admitted for CABG were allocated into two groups according to 'random numbers' technique. In a Group 1 (n=26) ITA was prepared keeping the pleura intact and in a Group 2 (n=28) pleura was opened. Both groups were compared in terms of postoperative respiratory functions, arterial blood gases, bleeding and clinical outcomes using ANOVA for repeated measurements analysis. RESULTS: Analysis of spirometric and partial oxygen pressure data showed that postoperative reductions in forced expiratory volume (0.17+/-0.18 lt vs. 0.28+/-0.14 lt, p=0.016), forced vital capacity (0.18+/-0.19 lt vs. 0.28+/-0.13 lt, p=0.037) and arterial oxygen measurements (-0.03+/-0.22 mmHg vs. 0.15+/-0.4 mmHg, p=0.023) were less pronounced in patients of Group 1 as compared with patients of Group 2. The increase in intrapulmonary shunts (Qs/Qt ratio) after the operation was more pronounced in Group 2 patients than in Group 1 patients (p<0.01) and the mean values of Qs/Qt ratio 24 hours after the operation were higher in group 2 as compared to Group 1 patients(0.100+/-0.063 vs. 0.054+/-0.048, p=0.001). Radiological evaluation revealed that costophrenic angle obliteration after operation more often occurred in Group 2 (14/28 patients) than in Group 1 (0/26 patients) (p<0.0001). Cardiothoracic index increased significantly after operation only in group 2 patients (p=0.001). Postoperative blood loss within 24 hours was significantly lower in Group 1 compared to Group 2 (656+/-179 ml vs. 907+/-257 ml, p=0.001). There was no significant difference between groups in the ICU stay duration (p=0.186), whereas the hospital stay was significantly longer in group 2 patients than in Group 1 patients (8.8+/-2.0 days vs. 7.6+/-2.0 days, p=0.039). CONCLUSION: According to our results, preserving pleural integrity has positive effects on the respiratory functions and patients' clinical outcomes following CABG operations.


Assuntos
Ponte de Artéria Coronária/métodos , Doença das Coronárias/fisiopatologia , Doença das Coronárias/cirurgia , Artéria Torácica Interna/cirurgia , Revascularização Miocárdica/métodos , Coleta de Tecidos e Órgãos/métodos , Adulto , Idoso , Análise de Variância , Gasometria , Feminino , Volume Expiratório Forçado , Humanos , Pulmão/fisiologia , Pulmão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Oxigênio/metabolismo , Hemorragia Pós-Operatória/epidemiologia , Período Pós-Operatório , Estudos Prospectivos , Testes de Função Respiratória , Método Simples-Cego , Espirometria , Resultado do Tratamento , Capacidade Vital
7.
Tex Heart Inst J ; 35(2): 203-5, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18612485

RESUMO

Noncardiac components of genetic disorders can complicate the operative and postoperative courses of pediatric cardiac surgery patients. Prolonged hospital stay, increased treatment cost, morbidity, and death are more likely in this subgroup of patients. Ventricular septal defect, which is a component of various genetic disorders, has a 22.3% incidence in VACTERL syndrome--a rare, nonrandom pattern of birth defects. Herein, we discuss the impact of ventricular septal defect closure in a 4-month-old girl who was diagnosed after birth with VACTERL syndrome.


Assuntos
Anormalidades Múltiplas , Anormalidades do Sistema Digestório , Comunicação Interventricular/cirurgia , Anormalidades Musculoesqueléticas , Complicações Pós-Operatórias , Feminino , Comunicação Interventricular/diagnóstico , Comunicação Interventricular/etiologia , Humanos , Lactente , Síndrome
8.
Anesth Analg ; 107(2): 614-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18633041

RESUMO

BACKGROUND: The aim of our study was to evaluate the pulmonary effects of noninvasive ventilation (NIV) with or without recruitment maneuver (RM) after open heart surgery. METHODS: One-hundred patients undergoing coronary artery bypass surgery were randomized into four groups after the operation: 1) RM with sustained inflation during mechanical ventilation postoperatively (RM group, n = 25); 2) RM combined with NIV applied for 1/2-h periods every 6 h in the first postoperative day after tracheal extubation (RM-NIV group, n = 25); 3) NIV after tracheal extubation (NIV group, n = 25); and 4) a control group consisting of patients receiving neither RM nor NIV (control group, n = 25). Pulmonary function tests, oxygenation index, and atelectasis on chest radiograph were evaluated and compared among the groups. RESULTS: RM provided higher arterial oxygen levels during mechanical ventilation and after tracheal extubation compared to other interventions. Oxygenation was better in the RM-NIV and NIV groups than in the control group (P = 0.02 and P = 0.008, respectively) at the end of the study. The postoperative atelectasis score of the control group (median: 1) was higher than those of the RM (1; P = 0.03), RM-NIV (0; P < 0.01) and NIV (0; P < 0.01) groups. Pulmonary function of the NIV groups on postoperative day 2 was better than in the other groups, whereas the tests were similar among the groups on postoperative day 7. CONCLUSIONS: NIV associated with RM provided better oxygenation both during and after the mechanical ventilation period. NIV either alone or in combination with RM provided lower atelectasis scores and better early pulmonary function tests compared to the control group, without a significant difference regarding the duration of mechanical ventilation, intensive care unit stay, and the length of hospitalization. NIV combined with RM is recommended after open heart surgery to prevent postoperative atelectasis and hypoxemia.


Assuntos
Ponte de Artéria Coronária , Respiração com Pressão Positiva/métodos , Cuidados Pós-Operatórios , Ponte Cardiopulmonar/efeitos adversos , Ponte de Artéria Coronária/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atelectasia Pulmonar/etiologia , Atelectasia Pulmonar/prevenção & controle
9.
Heart Surg Forum ; 11(1): E30-1, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18270135

RESUMO

Cardiac hydatid cyst is known to be a rarely occurring disease. The appearance of large cysts in the interventricular septum in childhood is even more rare. Although such cysts are usually asymptomatic, they can behave like valvular disorders, depending on their location. In addition, cardiac hydatid cysts originating from the interventricular septum carry the risk of rupturing into both ventricular cavities, which may lead to fatal complications. Thus, early surgical treatment is of extreme importance. We describe the case of a 7-year-old girl with a cardiac hydatid cyst that originated in the interventricular septum.


Assuntos
Equinococose/diagnóstico , Ventrículos do Coração/patologia , Estenose da Valva Pulmonar/diagnóstico , Animais , Criança , Equinococose/diagnóstico por imagem , Equinococose/cirurgia , Feminino , Ventrículos do Coração/cirurgia , Humanos , Estenose da Valva Pulmonar/diagnóstico por imagem , Estenose da Valva Pulmonar/cirurgia , Esterno/cirurgia , Ultrassonografia
10.
J Phys Chem B ; 111(44): 12668-75, 2007 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-17929960

RESUMO

Cadmium sulfide (CdS) nanoparticles (NPs) capped with poly(acrylic acid) (PAA) were prepared in aqueous solutions from Cd(NO3)2 and Na2S. Influence of the COOH/Cd ratio (0.8-12.5), reaction pH (5.5 and 7.5), and PAA molecular weight (2100 and 5100 g/mol) on the particle size, colloidal stability, and photoluminescence were investigated. A Cd/S ratio of <1 causes ineffective passivization of the surface with the carboxylate and therefore results in a red shift of the absorption band and a significant drop in photoluminescence. Therefore, the Cd/S ratio was fixed at 1.1 for all experiments studying the mentioned variables. PAA coating provided excellent colloidal stability at a COOH/Cd ratio above 1. Absorption edges of PAA-coated CdS NPs are in the range of 460-508 nm. The size of the NPs increases slightly with increasing PAA molecular weight and COOH/Cd ratio at pH 7.5. It is demonstrated that there is a critical COOH/Cd ratio (1.5-2) that maximizes the photoluminescence intensity and quantum yield (QY, 17%). Above this critical ratio, which corresponds to smaller crystal sizes (3.7-4.1 nm) for each reaction set, the quantum yield decreases and the crystal size increases. Moreover, CdS NPs prepared at pH 7.5 have significantly higher QY and absorb at lower wavelengths in comparison with those prepared at pH 5.5. Luminescence quenching has not been observed over 8 months.


Assuntos
Acrilatos/química , Resinas Acrílicas/química , Compostos de Cádmio/química , Polímeros , Pontos Quânticos , Sulfetos/química , Coloides/química , Concentração de Íons de Hidrogênio , Luminescência , Peso Molecular , Nanopartículas/química , Tamanho da Partícula , Fotoquímica , Polímeros/síntese química , Polímeros/química , Soluções/química , Propriedades de Superfície , Água/química
11.
Anesth Analg ; 104(2): 384-90, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17242096

RESUMO

BACKGROUND: The aim of our study was to evaluate the pulmonary and hemodynamic effects of two different recruitment maneuvers after open heart surgery. METHODS: Sixty patients undergoing coronary artery bypass surgery were randomized into three groups after operation: recruitment maneuver with continuous positive airway pressure (CPAP) (CPAP-40 group, n = 20), recruitment by positive end-expiratory pressure (PEEP) (PEEP-20 group, n = 20), and 5 cm H2O PEEP (PEEP-5 group, n = 20). In the CPAP-40 group, 40 cm H2O peak inspiratory pressure was applied for 30 s, then PEEP was reduced to 20 cm H2O and ventilation was continued with baseline variables with PEEP decreased until the best Pao2 was achieved. In the PEEP-20 group, 20 cm H2O PEEP was set for 2 min, tidal volume was adjusted to achieve a peak inspiratory airway pressure of 40 cm H2O during the maneuver, then PEEP was decreased until the best Pao2 had been achieved. In the PEEP-5 group, 5 cm H2O PEEP was applied postoperatively. RESULTS: The mean arterial blood pressure of the CPAP-40 group was lower than that of the PEEP-20 (P < 0.01) and PEEP-5 groups (P < 0.01) during the interventions. Oxygenation was higher in both recruitment groups than in the PEEP-5 group during the mechanical ventilation period. There was no significant difference among the groups beyond that period. The atelectasis score of the PEEP-5 group (1.3 +/- 0.9) on postoperative day 1 was higher than that of the CPAP-40 (0.65 +/- 0.6; P = 0.01) and PEEP-20 (0.65 +/- 0.5; P = 0.01) groups. CONCLUSIONS: The recruitment techniques with postmaneuver PEEP increased oxygenation and decreased atelectasis equally, whereas PEEP-20 provided more stable hemodynamic conditions than the CPAP maneuver.


Assuntos
Pressão Sanguínea/fisiologia , Ponte Cardiopulmonar , Pressão Positiva Contínua nas Vias Aéreas , Ponte de Artéria Coronária , Pulmão/fisiologia , Respiração com Pressão Positiva , Ventilação Pulmonar/fisiologia , Adulto , Pressão Positiva Contínua nas Vias Aéreas/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Assistência Perioperatória/métodos , Respiração com Pressão Positiva/métodos
12.
Intensive Care Med ; 32(6): 881-7, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16715328

RESUMO

OBJECTIVE: To evaluate procalcitonin and C-reactive protein as markers of inflammation severity and their value in predicting development of organ failure after pediatric open heart surgery. DESIGN: Prospective, observational, clinical study. SETTING: Single university hospital. PATIENTS: Thirty-three pediatric patients with systemic inflammatory response syndrome (SIRS; n=19) and SIRS+organ failure (SIRS+OF; n=14) following open heart surgery were included. MEASUREMENTS AND RESULTS: Plasma procalcitonin and C-reactive protein levels were measured before and after the operation, and 1, 2, 3, and 4 days after surgery. Patients were evaluated daily to assess organ failure. Postoperative procalcitonin levels in the SIRS+OF group were significantly higher than in the SIRS group. C-reactive protein levels were similar between the groups throughout the study period. Peak procalcitonin levels were found to be positively correlated with aortic cross-clamp and cardiopulmonary bypass times, duration of mechanical ventilation, intensive care unit and hospital stay, mortality and organ failure development. Peak procalcitonin was found to be a good predictor of postoperative organ failure development and mortality. However, the predictive value of peak C-reactive protein for organ failure and mortality was found to be weak. Double-peak procalcitonin curves were observed in SIRS+OF patients with infection during the intensive care unit stay. CONCLUSION: In the SIRS+OF group peak procalcitonin levels were found to be highly predictive for mortality and organ failure development, whereas C-reactive protein levels were not. Daily procalcitonin measurements in SIRS+OF patients may help identify the postoperative infection during the follow-up period.


Assuntos
Proteína C-Reativa/análise , Calcitonina/análise , Pediatria , Complicações Pós-Operatórias/imunologia , Precursores de Proteínas/análise , Síndrome de Resposta Inflamatória Sistêmica/etiologia , Cirurgia Torácica/métodos , Peptídeo Relacionado com Gene de Calcitonina , Criança , Pré-Escolar , Feminino , Humanos , Unidades de Terapia Intensiva , Masculino , Turquia
13.
Cardiol Young ; 16(1): 87-8, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16454885

RESUMO

Iatrogenic thrombosis within the heart is rare following intracardiac operations. We undertook surgery to correct a 30-month-old girl with Fallot's tetralogy. After a period of 6 months following the operation, echocardiography revealed a thrombus measuring 16 by 12 millimetres attached to the tendinous cords supporting the antero-superior leaflet of the tricuspid valve. Medical treatment having failed, we proceeded to surgical excision so as to avoid pulmonary embolisation. Histological examination confirmed the thrombotic nature of the mass.


Assuntos
Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Doenças das Valvas Cardíacas/etiologia , Trombose/etiologia , Valva Tricúspide , Pré-Escolar , Ecocardiografia , Feminino , Seguimentos , Doenças das Valvas Cardíacas/diagnóstico por imagem , Humanos , Doença Iatrogênica , Reoperação , Tetralogia de Fallot/cirurgia , Trombose/diagnóstico por imagem
15.
Intensive Care Med ; 30(4): 620-6, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-14722635

RESUMO

OBJECTIVE: To evaluate the effects of protective and conventional ventilation with or without positive end-expiratory pressure (PEEP), on systemic tumor necrosis factor-alpha, interleukin-6 levels and pulmonary function during open heart surgery. DESIGN: Prospective, randomized clinical study. SETTING: Single university hospital. PATIENTS AND PARTICIPANTS: Forty-four patients undergoing elective coronary artery bypass grafting surgery with cardiopulmonary bypass. INTERVENTIONS: Patients ventilated with (1) protective tidal volumes (6 ml/kg, respiratory rate: 15 breaths/min, PEEP 5 cmH(2)O, n=15) group PV; (2) conventional tidal volumes (10 ml/kg, respiratory rate: 9 breaths/min, PEEP 5 cmH(2)O, n=14) group CV+PEEP and (3) conventional tidal volumes (10 ml/kg, respiratory rate: 9 breaths/min, n=15) without PEEP, group CV+ZEEP. Various pulmonary parameters, systemic TNF-alpha and IL-6 levels were determined throughout the study. MEASUREMENTS AND RESULTS: There were no differences among the groups regarding the systemic TNF- alpha and IL-6 levels. The plateau airway pressures of group PV were lower than those of groups CV+PEEP ( p=0.02) and CV+ZEEP ( p=0.001) after cardiopulmonary bypass. The shunt fraction of group PV was significantly lower than that of group CV+ZEEP 24 h after surgery ( p<0.05). Oxygenation and the alveolar-arterial oxygen difference were better in both PEEP groups than in group CV+ZEEP 24 h after the operation. CONCLUSIONS: We could not find any evidence that protective mechanical ventilation prevents some of the adverse effects of cardiopulmonary bypass on the lung, nor systemic cytokine levels, postoperative pulmonary function or length of hospitalization.


Assuntos
Ponte Cardiopulmonar , Citocinas/metabolismo , Respiração Artificial/métodos , Idoso , Citocinas/sangue , Feminino , Frequência Cardíaca/fisiologia , Humanos , Interleucina-6/sangue , Interleucina-6/metabolismo , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva/efeitos adversos , Respiração com Pressão Positiva/métodos , Cuidados Pós-Operatórios , Cuidados Pré-Operatórios , Prognóstico , Estudos Prospectivos , Artéria Pulmonar/fisiopatologia , Pressão Propulsora Pulmonar/fisiologia , Respiração Artificial/efeitos adversos , Testes de Função Respiratória , Fator de Necrose Tumoral alfa/metabolismo
16.
Biosens Bioelectron ; 17(10): 875-81, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12243906

RESUMO

Organic peroxides, t-butyl hydroperoxide, 2-butanone peroxide, cumene hydroperoxide and t-butyl peracetate, were determined by an amperometric enzyme electrode. The enzyme electrode was prepared through electrostatic immobilization of horseradish peroxidase (HRP) in a polyvinylferrocenium (PVF) film. A PVF(+)ClO(4)(-) film was coated on a Pt foil at +0.70 V by electrooxidation of polyvinylferrocene in methylene chloride with 0.1 M tetrabutylammonium perchlorate (TBAP). The enzyme modified electrode PVF(+)HRP(-) was prepared by anion-exchange in a solution of HRP(-) in 0.05 M phosphate buffer at pH 8.5. FTIR spectroscopy was used to identify PVF, PVF(+)ClO(4)(-), and PVF(+)HRP(-). The immobilized amount of the enzyme in the film was determined by UV spectroscopy. The effects of the polymeric film thickness, bulk enzyme concentration used in the immobilization treatment and the temperature on the performance of enzyme electrode were investigated. The inhibitory effect of oxygen was also examined. Linearities, lower detection limits, active life times and sensitivities of the electrode were determined for each peroxide.


Assuntos
Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/metabolismo , Compostos Ferrosos , Peroxidase do Rábano Silvestre/metabolismo , Peróxidos/análise , Polivinil , Derivados de Benzeno/análise , Eletrodos , Estabilidade Enzimática , Temperatura
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