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Specific Sensitivity (specific + sensitivity)
Selected AbstractsThe NADH Electrochemical Detection Performed at Carbon Nanofibers Modified Glassy Carbon ElectrodeELECTROANALYSIS, Issue 14 2007Adina Arvinte Abstract In this work, the capability of carbon nanofibers to be used for the design of catalytic electrochemical biosensors is demonstrated. The direct electrochemistry of NADH was studied at a glassy carbon electrode modified using carbon nanofibers. A decrease of the oxidation potential of NADH by more than 300,mV is observed in the case of the assembled carbon nanofiber-glassy carbon electrode comparing with a bare glassy carbon electrode. The carbon nanofiber-modified electrode exhibited a wide linear response range of 3×10,5 to 2.1×10,3,mol L,1 with a correlation coefficient of 0.997 for the detection of NADH, a high specific sensitivity of 3637.65 (,A/M cm2), a low detection of limit (LOD=3,) of 11,,M, and a fast response time (3,s). These results have confirmed the fact that the carbon nanofibers represent a promising material to assemble electrochemical sensors and biosensors. [source] Evidence for early specialized processing of speech formant information in anterior and posterior human auditory cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2010Barrie A. Edmonds Abstract Many speech sounds, such as vowels, exhibit a characteristic pattern of spectral peaks, referred to as formants, the frequency positions of which depend both on the phonological identity of the sound (e.g. vowel type) and on the vocal-tract length of the speaker. This study investigates the processing of formant information relating to vowel type and vocal-tract length in human auditory cortex by measuring electroencephalographic (EEG) responses to synthetic unvoiced vowels and spectrally matched noises. The results revealed specific sensitivity to vowel formant information in both anterior (planum polare) and posterior (planum temporale) regions of auditory cortex. The vowel-specific responses in these two areas appeared to have different temporal dynamics; the anterior source produced a sustained response for as long as the incoming sound was a vowel, whereas the posterior source responded transiently when the sound changed from a noise to a vowel, or when there was a change in vowel type. Moreover, the posterior source appeared to be largely invariant to changes in vocal-tract length. The current findings indicate that the initial extraction of vowel type from formant information is complete by the level of non-primary auditory cortex, suggesting that speech-specific processing may involve primary auditory cortex, or even subcortical structures. This challenges the view that specific sensitivity to speech emerges only beyond unimodal auditory cortex. [source] Reduction of the Potential Anticancer Drug Oracin in the Rat Liver In-vitroJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2000BARBORA SZOTÁKOVÁ Studies on the metabolism of the potential cytostatic drug oracin have shown that a principal metabolite of oracin is 11-dihydrooracin (DHO). We conducted in-vitro experiments to investigate the extent of oracin carbonyl reduction in microsomal or cytosolic fractions and to find out the enzymes involved under these conditions. Among several inducers of rat cytochrome P450 only 3-methylcholanthrene caused a significant (P < 0.01) stimulation (1.9 times) of DHO production in microsomal fraction and the specific P4501A inhibitor ,-naphthoflavone significantly (P < 0.01) decreased (twice) the induced reduction activity. Cytochrome P4501A participates in oracin reduction in microsomes. 18,-Glycyrrhetinic acid, a specific inhibitor of hydroxysteroid dehydrogenase, significantly (P < 0.01) inhibited the production of DHO in the microsomal fraction (>95% inhibition) in comparison with the non-inhibited reaction. Statistically significant (P < 0.01) inhibition (95%) of DHO formation was caused by metyrapone, which is also the substrate of 11,-hydroxysteroid dehydrogenase. The main microsomal enzyme which catalyses the carbonyl reduction of oracin is probably 11,-hydroxysteroid dehydrogenase. Important oracin reduction to DHO in the cytosolic fraction was found. According to its specific sensitivity towards quercitrin (inhibition by 99%, P < 0.01), the enzyme responsible for DHO formation in the rat liver cytosol is postulated to be carbonyl reductase. [source] Thermal transfer in SWNTs and peapods under UV-irradiationPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007P. Puech Abstract Results of UV irradiation experiments in vacuum on SWNTs and peapods, as followed by in-situ Raman spectroscopy with increasing laser power up to 300 mW are reported. UV micro-Raman measurements were used to record spectra free of black-body radiation. Photon absorption was found to induce both the shifting and broadening of the G+ and G, bands. The local temperature increase (up to a temperature gain of ,1000 K) was able to be reliably calculated from the band feature variation, more specifically considering the G+ band. Meanwhile, a specific sensitivity to oxidation of the nanotubes from peapods was revealed, due the fullerene-catalysed dissociation of molecular oxygen traces into active species. In addition, both silica and diamond substrates were used. The different thermal conductivity of the substrates has the effect of changing the laser power levels needed to induce structural transformations. Carrying-out UV irradiation of nanotube-based material while monitoring the induced temperature via in situ Raman spectroscopy therefore appears as a new tool likely to be useful for the nano-engineering of nanotube-based devices. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Alterations of Mitochondria in Peripheral Blood Mononuclear Cells of Vitiligo PatientsPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2003Maria Lucia Dell'Anna The possible role for a defective mitochondrial functionality in the pathogenesis of vitiligo was investigated by measuring intracellular levels of reactive oxygen species and of antioxidants, the activity of Krebs cycle enzymes, as well as the effects of inhibitors of the electron transport chain, in peripheral blood mononuclear cells from patients with active or stable disease vs. normal subjects. Plasma glyoxal levels were also determined in the same groups of subjects as an index of systemic oxidative stress. In patients with vitiligo in active phase, we observed an increased intracellular production of reactive oxygen species with a consequent imbalance of the prooxidant/antioxidant equilibrium, whereas plasma did not show apparent alterations in glyoxal levels, ruling out a systemic oxidative stress. In patients with stable disease, the balance between pro-oxidants and anti-oxidants seems to be maintained. Moreover, a marked increase in the expression of mitochondrial malate dehydrogenase activity and a specific sensitivity to electron transport chain complex I inhibitor were observed. Overall, these data provide further evidence for an altered mitochondrial functionality in vitiligo patients. [source] | ||||||||||