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1.
Clin Exp Rheumatol ; 42(6): 1205-1214, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38910579

RESUMO

OBJECTIVES: The objective of this study is to ascertain the disparities in demographic features and biochemical profiles between individuals diagnosed with fibromyalgia (FM) and a control group of healthy individuals. METHODS: This retrospective, cross-sectional study compared the demographic, biochemical, metabolic, and inflammatory indexes and rates of 174 FM patients diagnosed using the American College of Rheumatology 2016 diagnostic criteria between January 2023 and January 2024, and 186 healthy control groups. RESULTS: There was no difference between the FM and control groups in terms of alcohol consumption, marital status, or diabetes mellitus. The smoking rate is higher, and the educational level was found to be lower for FM versus the control. There was no significant difference between FM and controls regarding waist-height ratio, triglyceride-glucose index, plasma atherogenic index, vitamin B12, and folate levels. Monocyte HDL ratio, cardiometabolic index, magnesium, HbA1c, and ferritin levels were significantly higher in the control than in FM (p<0.001, p=0.039, p=0.007, p<0.001, p<0.001, respectively). C-reactive protein, erythrocyte sedimentation rate, systemic immune-inflammatory index, neutrophil-lymphocyte rate, platelet lymphocyte rate, and vitamin D levels were found to be higher in FM compared to control (p=0.001, p=0.032, p=0.003, p=0.030, p=0.003, p<0.001, respectively). A weak positive correlation was observed between the fibromyalgia impact questionnaire (FIQ) score and disease duration, as well as between pain degree and ESR, and pain degree and CRP. The study revealed a weak inverse relationship between Widespread Pain Index (WPI) and waist circumference. CONCLUSIONS: This study highlights fthe association f ibromyalgia with elevated inflammatory markers, altered metabolic parameters, and specific demographic characteristics.


Assuntos
Biomarcadores , Fibromialgia , Humanos , Fibromialgia/sangue , Fibromialgia/epidemiologia , Fibromialgia/diagnóstico , Estudos Retrospectivos , Feminino , Estudos Transversais , Masculino , Pessoa de Meia-Idade , Adulto , Biomarcadores/sangue , Inflamação/sangue , Inflamação/epidemiologia , Mediadores da Inflamação/sangue , Estudos de Casos e Controles
2.
Clin Lab ; 62(4): 645-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27215084

RESUMO

BACKGROUND: The aim of the study was to investigate oxidant/antioxidant status by determining serum ischemia-modified albumin (IMA) levels with oxidative/antioxidant parameters in patients with ankylosing spondylitis (AS) compared to the controls. METHODS: The serum concentrations of IMA, IMA/albumin ratio (IMAR), malondialdehyde (MDA), total oxidant status (TOS), oxidative stress index (OSI), superoxide dismutase (SOD), glutathione peroxidase (GPx), and total antioxidant capacity (TAC) were measured in 40 AS patients and 35 healthy controls. RESULTS: Mean serum IMA, IMAR, MDA, TOS, and OSI levels were increased in patients with AS when compared to the control group (p < 0.05 for all). Serum levels of SOD and GPx were significantly lower in the patient group than in the healthy subjects (p < 0.001 for both). Serum TAC levels were decreased in patients with AS compared to the controls but the statistical difference was not significant. Serum IMA levels were found to be positively correlated with BASDAI, BASFI, BASMI, and ASDAS-CRP (r = 0.356, r = 0.370, r = 0.412, r = 0.353, respectively, and p < 0.05 for all). IMAR values showed significant correlations with BASFI, BASMI, and ASDAS-CRP (r = 0.351, p = 0.026; r = 0.400, p = 0.010; and r = 0.379, p = 0.016, respectively). CONCLUSIONS: Depletion in antioxidant systems and overproduction of free radicals leading to formation of the oxidative stress may play a role in the development of AS. Increased levels of IMA might provide important contributions to the underlying oxidative stress in AS.


Assuntos
Espondilite Anquilosante/metabolismo , Adulto , Biomarcadores/sangue , Feminino , Humanos , Masculino , Malondialdeído/sangue , Pessoa de Meia-Idade , Óxido Nítrico/sangue , Espécies Reativas de Oxigênio/metabolismo , Albumina Sérica , Albumina Sérica Humana , Superóxido Dismutase/sangue
3.
Pak J Pharm Sci ; 28(5): 1757-61, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26408895

RESUMO

Cyanobacteria (blue-green algae) form an important component of integrated nutrient managements in agriculture and are exploited in commercial biotechnological ventures. In this study, Rivularia bullata (Poir) Berkeley ex Bornet & Flahault, Nostocs pongiaeforme C. Agardh ex Bornet & Flahault were researched for their amino acid composition and crude protein values. R. bullata was collected from coastal zones of the Gulf of Saros and N. spongiaeforme from the Ayazma Stream. The levels of amino acids were measured in algae samples using EZ: fast kits (EZ: fast GC/FID Protein Hydrolysate Amino Acid Kit) by gas chromatography. The crude proteins of samples were determined by the Kjeldahl method and were calculated using a nitrogen conversion factor of 6.25. Thirty-two amino acids were investigated, for N. spongiaeforme eight free essential amino acids (EAA), eight free non-essential amino acids (NEAA) and eleven other amino acids (OAA); for R. bullata eight EAA, eight NEAA and eight OAA were detected. Aspartic acid is the major constituent for both species. The total protein percents were determined for N. spongiaeforme as % 19.83 and for R. bullata as % 6.15. When considering the increasing world population and reducing natural products; Cyanobacteria will benew feed sources for all living.


Assuntos
Aminoácidos/análise , Proteínas de Bactérias/análise , Cianobactérias/química , Turquia
4.
Turk Kardiyol Dern Ars ; 43(7): 599-606, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26536984

RESUMO

OBJECTIVE: Gilbert's syndrome (GS) is an autosomal recessive disease that is characterized by an increase in indirect bilirubin (IB). The incidence of atherosclerotic heart disease is decreased in GS. This study aimed to investigate the relation between pulse wave velocity (PWV) and the presence of GS. METHODS: The study included 58 GS patients (32 females, age; 27.12 ± 7.27 years, 26 males, age; 26.63 ± 5.84 years) admitted to the internal medicine clinic of the hospital. The control group included 58 healthy individuals (35 females [27.33 ± 8.06 years old, p=0.716] and 23 males [27.38 ± 6.91 years old, p=0.923]). PWV of both groups was measured from the right carotid and femoral arteries. RESULTS: Mean age of the GS group was 26.03 ± 8.22 years, while that of the healthy group was 26.60 ± 5.84 years. The GS group's diastolic blood pressure and PWV were significantly lower than those of the control group: 67.76 ± 8.59 mmHg vs 71.72 ± 7.28 mmHg; p=0.008, and 5.63 ± 1.12 m/s vs 6.18 ± 1.22 m/s; p=0.014 respectively. The GS group's high density lipoprotein (HDL) level was significantly higher than that of the control group: 1.4 ± 0.3 mmol/L vs 1.2 ± 0.3 mmol/L, p=0.029. CONCLUSION: This study found PWV among GS patients to be lower than that among non-smoking and aged-matched healthy controls.


Assuntos
Aorta/fisiopatologia , Bilirrubina/sangue , Doença da Artéria Coronariana/fisiopatologia , Doença de Gilbert , Adulto , Velocidade do Fluxo Sanguíneo , Estudos de Casos e Controles , Doença da Artéria Coronariana/sangue , Estudos Transversais , Feminino , Humanos , Masculino , Fluxo Pulsátil , Rigidez Vascular
5.
Metab Syndr Relat Disord ; 22(4): 269-275, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38252497

RESUMO

Background: The risk of atherosclerosis is increased in individuals with rheumatological disease. The objective of this study is to examine the heightened susceptibility to atherosclerosis in persons afflicted with rheumatological disorders. This study aimed to assess the impact of anti-tumor necrosis factor (anti-TNF) medication on the plasma atherogenic index (PAI) in persons diagnosed with rheumatological disease. Methods: This study used a retrospective cross-sectional design to investigate a cohort of 136 patients with rheumatological disease who were undergoing anti-TNF therapy (Group 1), as well as a comparison group of 117 patients getting conventional therapy (Group 2). Measurements of PAI were conducted at the initial baseline and again at the sixth month of treatment. Results: Initially, there was no statistically significant disparity observed in PAI values between the two cohorts. After a period of 6 months, a notable reduction in PAI was identified in the group receiving anti-TNF medication (P = 0.01), while no significant alteration was detected in the group receiving conventional treatment. Conclusion: It provides findings showing that anti-TNF therapy can reduce the PAI in individuals with rheumatological disease. This may indicate a potential cardiovascular protective effect of anti-TNF therapy.


Assuntos
Aterosclerose , Doenças Reumáticas , Fator de Necrose Tumoral alfa , Humanos , Masculino , Estudos Retrospectivos , Feminino , Aterosclerose/sangue , Aterosclerose/etiologia , Aterosclerose/tratamento farmacológico , Aterosclerose/epidemiologia , Pessoa de Meia-Idade , Doenças Reumáticas/tratamento farmacológico , Doenças Reumáticas/sangue , Doenças Reumáticas/complicações , Estudos Transversais , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Adulto , Antirreumáticos/uso terapêutico , Idoso , Resultado do Tratamento
6.
Rev Assoc Med Bras (1992) ; 70(7): e20240091, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39045935

RESUMO

OBJECTIVE: We aimed to evaluate the risk of hepatitis B virus reactivation in rheumatic patients using anti-tumor necrosis factor-alpha drugs and the awareness of physicians about hepatitis B virus reactivation. METHODS: Demographic characteristics, pre- and post-treatment hepatitis markers, and laboratory parameters of patients receiving anti-tumor necrosis factor-alpha therapy in our rheumatology clinic were retrospectively examined. RESULTS: A total of 448 patients, 240 (53.6%) female and 208 (46.4%) male, were evaluated. Their mean age was 48.02±14.64 years. While HBsAg was examined in 443 (98.9%) patients before treatment, 7 (1.6%) patients were found to be HBsAg positive. While anti-HBc IgG was examined in 405 (90.4%) patients, it was positive in 69 (17%) patients. HBs Ag (total 446-99.6%) test was performed in three patients who were not tested for HBsAg before the treatment, and anti-HBc total (431-96.2% total) test was performed in 26 patients who were not tested for anti-HBc total. All HBsAg positive patients and 17 (24.6%) of those with previous hepatitis B received antiviral treatment. While the median follow-up period of the patients was 24 (6-60) months, no patient developed hepatitis B virus reactivation. CONCLUSION: The screening rates and awareness of physicians providing anti-tumor necrosis factor-alpha therapy for hepatitis B virus infection were found to be higher compared to similar studies. Hepatitis B virus reactivation did not develop in any patient. Since the risk of hepatitis B virus reactivation is low, especially in patients with previous hepatitis B, it would be more appropriate to follow up the patients without giving antiviral prophylaxis.


Assuntos
Antígenos de Superfície da Hepatite B , Vírus da Hepatite B , Hepatite B , Doenças Reumáticas , Fator de Necrose Tumoral alfa , Ativação Viral , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Estudos Retrospectivos , Adulto , Ativação Viral/efeitos dos fármacos , Doenças Reumáticas/tratamento farmacológico , Vírus da Hepatite B/fisiologia , Vírus da Hepatite B/imunologia , Antígenos de Superfície da Hepatite B/sangue , Fatores de Risco , Antirreumáticos/efeitos adversos , Antirreumáticos/uso terapêutico , Anticorpos Anti-Hepatite B/sangue , Idoso
7.
Environ Sci Pollut Res Int ; 31(18): 27014-27036, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38499927

RESUMO

This study aims to investigate the metal content, fatty acid composition, lipid quality, and potential health risks of Pontastacus leptodactylus crayfish inhabiting Atikhisar Dam Lake. The research covers a 12-month period and includes both male and female individuals. The study investigated the metal content of crayfish specimens. In female individuals, the metal concentrations were ranked as Fe > Zn > Al > Cu > Mn > Se > As > Hg > Cd > Pb, while in male individuals, the ranking was Fe > Al > Zn > Cu > Mn > Se > As > Hg > Pb > Cd. The results demonstrate that Atherogenicity Index (AI) values for both genders range between 0.21 and 0.31, and Thrombogenicity Index (TI) values fall within 0.14 and 0.20. This indicates that crayfish meat is composed of healthy and high-quality fatty acids. In male individuals, omega-3 values range from 25.28 ± 0.380% to 28.34 ± 0.430%, and in female individuals, they vary from 22.98 ± 0.195% to 28.73 ± 0.871%. These findings underscore the absence of significant health risks associated with mercury levels in crayfish meat. Monthly meal calculations reveal that consuming female crayfish at an average of 4.35 servings per month for adults and 2.24 servings per month for children presents no health hazards. Similarly, the consumption of crayfish meat at an average of 5.29 servings per month for adult males and 2.72 servings per month for male children is deemed safe for health. Based on these results, the lipid quality of both male and female individuals from this species is found to be beneficial, as confirmed by risk-benefit assessments.


Assuntos
Astacoidea , Ácidos Graxos , Lagos , Lipídeos , Poluentes Químicos da Água , Animais , Lagos/química , Metais , Masculino , Monitoramento Ambiental , Feminino
8.
Rev. Assoc. Med. Bras. (1992, Impr.) ; 70(7): e20240091, 2024. tab
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1565039

RESUMO

SUMMARY OBJECTIVE: We aimed to evaluate the risk of hepatitis B virus reactivation in rheumatic patients using anti-tumor necrosis factor-alpha drugs and the awareness of physicians about hepatitis B virus reactivation. METHODS: Demographic characteristics, pre- and post-treatment hepatitis markers, and laboratory parameters of patients receiving anti-tumor necrosis factor-alpha therapy in our rheumatology clinic were retrospectively examined. RESULTS: A total of 448 patients, 240 (53.6%) female and 208 (46.4%) male, were evaluated. Their mean age was 48.02±14.64 years. While HBsAg was examined in 443 (98.9%) patients before treatment, 7 (1.6%) patients were found to be HBsAg positive. While anti-HBc IgG was examined in 405 (90.4%) patients, it was positive in 69 (17%) patients. HBs Ag (total 446-99.6%) test was performed in three patients who were not tested for HBsAg before the treatment, and anti-HBc total (431-96.2% total) test was performed in 26 patients who were not tested for anti-HBc total. All HBsAg positive patients and 17 (24.6%) of those with previous hepatitis B received antiviral treatment. While the median follow-up period of the patients was 24 (6-60) months, no patient developed hepatitis B virus reactivation. CONCLUSION: The screening rates and awareness of physicians providing anti-tumor necrosis factor-alpha therapy for hepatitis B virus infection were found to be higher compared to similar studies. Hepatitis B virus reactivation did not develop in any patient. Since the risk of hepatitis B virus reactivation is low, especially in patients with previous hepatitis B, it would be more appropriate to follow up the patients without giving antiviral prophylaxis.

9.
Saudi J Kidney Dis Transpl ; 28(1): 68-75, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28098105

RESUMO

Although not mandatory for patients, many Muslims fast in Ramadan. We aimed to investigate the effects of long hours (17.5) fasting on renal functions in patients with chronic kidney disease (CKD). Stage 3-5 CKD patients with stable renal function were recruited to this prospective observational study three months ahead of Ramadan in 2015. All patients were instructed regarding possible deleterious effects of dehydration caused by fasting. Forty-five patients (mean age 66.8 ± 10.3 years, 68.8% male) chose to fast and 49 (mean, age: 64.1 ± 12.6 years, 51% male) chose not to fast. Clinical and laboratory data were recorded before and after Ramadan. Baseline clinical and laboratory parameters were similar in the two groups, except for higher serum creatinine and lower estimated glomerular filtration rate (eGFR) in the nonfasting group (2.22 ± 0.99 vs. 1.64 ± 0.41 mg/dL, P <0.001 and 3 1.9 ± 12.4 vs. 42.6 ± 9.8 mL/min, P <0.001, respectively). More than 30% elevation in serum creatinine after Ramadan occurred in 8.8% and 8.1% of fasting and nonfasting patients, respectively (P = 0.9). More than 25% drop eGFR after Ramadan was noted in seven (15.5%) and six (12.2%) fasting and nonfasting patients, respectively (P = 0.642). Patients with ≥ 25% drop in eGFR (13 vs. 81) were older (72.3 ± 8.3 years vs. 64.3 ± 11.7 years, P = 0.020) and more frequently using diuretics (69.2% vs. 35.8%, P = 0.023). In multiple linear regression analysis, only advanced age was found to be associated with ≥25% drop in eGFR after Ramadan in the fasting group. Fasting during Ramadan was not associated with increased risk of declining in renal functions in patients with Stage 3-5 CKD. However, elderly patients may still be under a higher risk.


Assuntos
Jejum , Férias e Feriados , Islamismo , Rim/fisiopatologia , Insuficiência Renal Crônica/fisiopatologia , Idoso , Progressão da Doença , Jejum/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Insuficiência Renal Crônica/diagnóstico , Medição de Risco , Fatores de Risco , Turquia
10.
Talanta ; 147: 315-21, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26592613

RESUMO

A novel amperometric glucose biosensor was proposed in flow injection analysis (FIA) system using glucose oxidase (GOD) and Quantum dot (ZnS-CdS) modified Pencil Graphite Electrode (PGE). After ZnS-CdS film was electrochemically deposited onto PGE surface, GOD was immobilized on the surface of ZnS-CdS/PGE through crosslinking with chitosan (CT). A pair of well-defined reversible redox peak of GOD was observed at GOD/CT/ZnS-CdS/PGE based on enzyme electrode by direct electron transfer between the protein and electrode. Further, obtained GOD/CT/ZnS-CdS/PGE offers a disposable, low cost, selective and sensitive electrochemical biosensing of glucose in FIA system based on the decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen. Under optimum conditions (flow rate, 1.3mL min(-1); transmission tubing length, 10cm; injection volume, 100µL; and constant applied potential, -500mV vs. Ag/AgCl), the proposed method displayed a linear response to glucose in the range of 0.01-1.0mM with detection limit of 3.0µM. The results obtained from this study would provide the basis for further development of the biosensing using PGE based FIA systems.


Assuntos
Técnicas Biossensoriais/instrumentação , Enzimas Imobilizadas/química , Glucose Oxidase/química , Glucose/análise , Grafite/química , Pontos Quânticos/química , Aspergillus niger/enzimologia , Técnicas Biossensoriais/economia , Compostos de Cádmio/química , Quitosana/química , Eletroquímica , Eletrodos , Enzimas Imobilizadas/metabolismo , Análise de Injeção de Fluxo , Glucose Oxidase/metabolismo , Limite de Detecção , Sulfetos/química , Compostos de Zinco/química
11.
Iran J Kidney Dis ; 9(3): 221-9, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25957427

RESUMO

INTRODUCTION: Methotrexate, an antagonist of folic acid used in the treatment of many cancers and inflammatory diseases, is associated with side effects that limit its usage. Infliximab has been reported to have a protective effect against nephrotoxicity induced by some drugs and ischemic reperfusion. We aimed to investigate whether infliximab has a protective effect against methotrexate-induced nephrotoxicity. MATERIALS AND METHODS: We administered methotrexate at a dose of 20 mg/kg as a single intraperitoneal injection in 10 rats (methotrexate group). Another group of 10 rats received a single dose of infliximab, 7 mg/kg, intraperitoneally (infliximab group). The methotrexate and infliximab group received a similar single injection of infliximab 72 hours prior to methotrexate injection. After 72 hours a single dose of methotrexate, 20 mg/kg, was administered intraperitoneally. Five days after methotrexate injection, blood samples were collected and the kidney tissues were removed for biochemical and histological examination. RESULTS: The methotrexate group had significantly higher tissue levels of tumor necrosis factor-α (P = .008), interleukin-1ß (P = .04), nitric oxide (P < .001), and adenosine deaminase (P < .001) than the methotrexate and infliximab group after the 5-day study. The methotrexate group also had significantly higher total histological scores (P < .001) and carbonic anhydrase-II activity (P < .001) when compared to the methotrexate and infliximab group. CONCLUSIONS: Infliximab has a strong protective effect against methotrexate-induced nephrotoxicity by suppressing cytokines release. It may decrease methotrexate-induced nephrotoxicity by regulating carbonic anhydrase-II enzyme activities and slowing down purine metabolism.


Assuntos
Citocinas/metabolismo , Infliximab/farmacologia , Rim/efeitos dos fármacos , Rim/imunologia , Metotrexato/toxicidade , Substâncias Protetoras/farmacologia , Adenosina Desaminase/metabolismo , Animais , Anticorpos Monoclonais/farmacologia , Antimetabólitos Antineoplásicos/toxicidade , Anidrase Carbônica II/metabolismo , Inflamação/tratamento farmacológico , Interleucina-1beta/metabolismo , Rim/lesões , Rim/patologia , Masculino , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Fatores de Tempo , Resultado do Tratamento , Fator de Necrose Tumoral alfa/metabolismo
12.
J Family Med Prim Care ; 3(4): 456-7, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25657966

RESUMO

A 74-year-old male patient with type 2 diabetes mellitus admitted to the emergency department with the complaints of progressive breathlessness, dry cough, and swollen lower extremities. Our patient had type 2 diabetes mellitus and hypertension for 3 years. His HbA1c was not within the target range so sitagliptin was added to on-going therapy. After 1 week of starting sitagliptin therapy, even though the patient had not heart failure he applied to the emergency department with a complaint of dyspnea. The cardiovascular safety and efficacy of many anti-hyperglycemic agents such as sitagliptin, saxagliptin are unclear. Our case has shown that dipeptidyl peptidase 4 inhibitors may cause pulmonary edema. Hence, it should be used with cautious, especially in patients with heart failure.

13.
Int J Clin Exp Med ; 7(10): 3536-42, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25419394

RESUMO

Crimean-Congo hemorrhagic fever (CCHF) virus can cause potentially fatal infections in humans. During this disease, cytokines are intensive released. Resistin which is a good marker of inflammation is an adipocytokine released from adipose tissue. We aimed to investigate whether serum resistin level in patients with CCHF has a prognostic value in predicting recovery time. Twenty men and 22 women (a total of 42 CCHF patients) and a similar age group of 40 healthy individuals (16 men and 24 women) were included in the study. Hematologic tests, serum resistin level, C-reactive protein (CRP) and others biochemical values of all the two group subjects were evaluated. Multivariate logistic regression analysis was performed. Resistin level of patients with CCHF was higher than the controls (1252.6±864.7 ng/ml vs. 824.1±224.6 ng/ml, p=0.003). There was strongly association among recovery time, increased resistin level (p < 0.001), prothrombin time (PT) (p < 0.001), INR (p < 0.001), decreased white blood cell count (WBC) (p=0.012) and lower platelet counts (p=0.007). Serum resistin level is significantly elevated in CCHF patients. Resistin level may be a good prognostic factor to predict recovery time in patients with CCHF.

14.
Colloids Surf B Biointerfaces ; 102: 816-21, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23107961

RESUMO

In the present study, the electrocatalytic oxidation of reduced ß nicotinamide adenine dinucleotide (NADH) was investigated using a pencil graphite electrode modified with quercetin (PGE/QH(2)). The PGE/QH(2) was prepared through two steps: (i) the pre-treatment of PGE at 1.40 V vs. Ag|AgCl|KCl((sat.)) in pH 7.0 phosphate buffer containing 0.1 M KCl for 60s and (ii) adsorption of QH(2) on the PGE via immersion of PGE into a 1.0mM QH(2) solution (in ethanol) for 60s. Cyclic voltammetric studies show that the peak potential of NADH oxidation shifts from +500 mV at bare PGE to +300 mV at PGE/QH(2). The electrocatalytic currents obtained from amperometric measurements at +300 mV vs. Ag|AgCl|KCl((sat.)) and in phosphate buffer solution at pH 7.0 containing 0.1M KCl were linearly related to the concentration of NADH. Linear calibration plots are obtained in the concentration range from 0.5 µM to 100 µM. The limit of detection was found to be 0.15 µM.


Assuntos
Eletroquímica/métodos , Eletrodos , Grafite/química , NAD/química , Quercetina/química , Oxirredução
15.
Talanta ; 89: 490-5, 2012 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-22284522

RESUMO

This study describes a new approach for the investigation of electrocatalytic oxidation of sulfide using a pencil graphite electrode modified with quercetin (PGE/QH(2)). Adsorption procedure was used for the preparation of the modified electrodes. It was observed that PGE/QH(2) showed a significant electrocatalytic activity toward sulfide oxidation. Cyclic voltammetric studies show that the peak potential of sulfide shifts from +450 mV at bare PGE to +280 mV at PGE/QH(2). The electrocatalytic currents obtained from amperometric measurements at +300 mV vs. Ag/AgCl/KCl(sat) and at pH 8.0 BR buffer solution containing 0.1M NH(4)Cl were linearly related to the concentration of sulfide. The calibration graph consisted of two linear segments of 1-20 µM and 20-800 µM with a detection limit of 0.3 µM (based on 3s(b)). The proposed method was successfully applied to the determination of sulfide in waste waters and was compared with the spectrophotometric method.


Assuntos
Quercetina/química , Sulfetos/análise , Poluentes Químicos da Água/análise , Água/química , Adsorção , Cloreto de Amônio/química , Técnicas Biossensoriais/métodos , Soluções Tampão , Calibragem , Eletroquímica , Eletrodos , Grafite/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Oxirredução , Espectrofotometria , Eliminação de Resíduos Líquidos
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