Developing an elegant and integrated electrochemical-theoretical approach for detection of DNA damage induced by 4-nonylphenol.

In this work, a novel biosensor was fabricated for detection of DNA damage induced by 4-nonylphenol (NP) and also determination of NP. To achieve this goal, a glassy carbon electrode (GCE) was modified with chitosan (Chit), gold nanoparticles (Au NPs) and DNA-multiwalled carbon nanotubes (DNA-MWCNTs). Then, the DNA-MWCNTs/Au NPs/Chit/GCE was incubated with methylene blue (MB) to obtain MB-DNA-MWCNTs/Au NPs/Chit/GCE in which MB was used as the redox indicator. The modifications applied to the GCE were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopic (EDS) and theoretical evidence. MB is a derivative of anthraquinone which can intercalate into double helix structure of DNA. By treating MB-DNA-MWCNTs/Au NPs/Chit/GCE with NP, a higher R ct was observed because the insertion of the NP may result in a more negative charge environment on the DNA surface which hinders accessibility of [Fe(CN)6]3-/4- anion to the electrode surface. Change in the EIS response of the biosensor in the presence of NP was used to develop a novel system for monitoring the DNA damage induced by NP. The EIS technique was also used to develop a sensitive electroanalytical method for determination of NP.

Diagnostic performance of 64-channel multislice computed tomography in assessment of significant coronary artery disease in symptomatic subjects.

The recent development of 64-channel multislice computed tomography (MSCT) has resulted in noninvasive coronary artery imaging improvement. This study was conducted to determine the accuracy of 64-slice MSCT in a relatively unselected group of 143 patients with presentations suggestive of coronary artery disease, including those with unstable angina pectoris, who underwent both coronary computed tomographic angiography and invasive coronary angiography. No arrhythmia was considered an exclusion criterion except for atrial fibrillation or frequent extrasystoles. In patients with fast heart rates, a beta blocker was administered orally. Data were obtained using electrocardiography gated 64-slice MSCT. Computed tomographic angiography and invasive coronary angiography findings of each coronary segment were compared to determine the sensitivity, specificity, positive predictive value, and negative predictive value of MSCT in the detection of their normalcy or insignificant (<50% diameter decrease) stenosis versus significant (>or=50% diameter decrease) stenosis or total occlusion. In per-patient assessment, the calculated sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 96%, 67%, 91%, and 83%, respectively. These values in per-artery evaluation were 94%, 94%, 87%, and 97%, and corresponding values in per-segment analysis were 92%, 97%, 77%, and 99%, respectively. In conclusion, computed tomographic angiography has high diagnostic performance in the assessment of significant coronary artery disease in most patients in a daily routine practice, including those presenting with unstable angina pectoris symptoms.