Computerized quantification of carotid artery stenosis using MRA axial images

Currently, the North American symptomatic carotid endarterectomy trial, European carotid surgery trial, and common carotid method are used to measure the carotid stenosis for determining candidates for carotid endarterectomy using the projection angiography from different modalities such as digital subtraction angiography, rotational angiography, computed tomography angiography and magnetic resonance angiography. A new computerized carotid stenosis measuring system was developed using MR angiography axial image to overcome the drawbacks of conventional carotid stenosis measuring methods, to reduce the variability of inter-observer and intra-observer. The gray-level thresholding is one of the most popular and efficient methods for image segmentation. We segmented the carotid artery and lumen from three-dimensional time-of-flight MRA axial images using gray-level thresholding technique. Using the measured intima-media thickness value of common carotid artery for each case, we separated carotid artery wall from the segmented carotid artery region. After that, the regions of segmented carotid without artery wall were divided into region of blood flow and plaque. The calculation of carotid stenosis degree was performed as follows: carotid stenosis grading = (area measure of plaque/area measure of blood flow region and plaque) * 100%. No previous study has developed the carotid stenosis measuring method using MRA axial image. The new computerized stenosis measuring system has advantage over conventional caliper measuring methods; it will not only greatly increase the speed of stenosis measuring but also reduce the variability between readers. It should also reduce the variability between different institutions.     

Discretely tunable erbium-doped fiber ring laser selecting ITU-T grids of 273 channels × 50-GHz spacing in <Emphasis Type="Italic">C</Emphasis>- and <Emphasis Type="Italic">L</Emphasis>-band regions

We report the fabrication of a discretely tunable erbium-doped fiber ring laser with a novel scheme that can select ITU-T grids of 50-GHz spacing in both C and L bands. Wavelength selections of 273 channels are demonstrated with a signal to source spontaneous emission ratio of 60 dB/nm and excellent power flatness over 111-nm bandwidth. This was realized by incorporating both a solid Fabry–Pérot interferometer and a fiber Fabry–Pérot tunable filter into the ring laser. To our knowledge, our experimental result has the widest tuning range ever reported for a discretely tunable fiber laser with 50-GHz channel spacing that matches the ITU-T grids and is the first equipment that can operate in both C and L bands. PACS 42.55.Wd; 42.60.Da; 42.60.-v     

Simple and extractionless high-performance liquid chromatographic determination of rosiglitazone in human plasma and application to pharmacokinetics in humans

A simple and extractionless HPLC method using fluorescence detection was developed for the determination of rosiglitazone in human plasma. After deproteinization using perchloric acid the plasma samples were directly injected onto the HPLC system. The mobile phase was composed of acetonitrile (52%) and 20 mm ammonium acetate (48%, pH 7.5), and analysis was run at a flow rate of 0.2 mL/min with the detector operating at 247 nm for excitation wavelength and at 367 nm for emission wavelength, respectively. The method has a mean recovery of 97%, while the intra-day and inter-day precisions were all less than 7%. This method is simple, specific, sensitive and requires only a small plasma volume with short analytical time, and is suitable for the determination of plasma rosiglitazone in routine measurements for pharmacokinetic studies.     

Enantioseparation using sulfated cyclosophoraoses as a novel chiral additive in capillary electrophoresis

Highly sulfated cyclosophoraoses (HS-Cys) were synthesized by the chemical modification of a family of neutral cyclosophoraoses isolated from Rhizobium leguminosarum bv. trifolii. The HS-Cys were then analytically characterized using Fourier transform-infrared spectroscopy and elemental analysis. These HS-Cys were successfully used as a novel chiral additive, in low-pH aqueous background electrolytes, for capillary electrophoretic separation of five basic chiral drugs such as arterenol, atenolol, isoproterenol, propranolol, and metoprolol.     

Frictional dynamics of fluorine-terminated alkanethiol self-assembled monolayers

The frictional dynamics of fluorine-terminated alkanethiol (S(CH2)8CF3) self-assembled monolayers (SAMs) on gold are studied using molecular dynamics simulations. The simulations treat the interactions between two SAMs on flat surfaces. The structure and frictional behavior are investigated as a function of applied pressure (200 MPa to 1 GPa) for a shear velocity of 2 m/s and compared to methyl-terminated alkanethiol SAMs. The maximum adhesive pressure between the SAMs is 220 MPa for both end groups. In agreement with experiments on the molecular scale, the shear stress and the coefficient of friction for CF3-terminated alkanethiols are larger than for CH3-terminated alkanethiols. The main source for the difference is primarily the tighter packing of the fluorinated terminal group resulting in a higher degree of order. The molecular scale coefficient of friction is correlated with the degree of order among all the systems.     

Nuclear magnetic resonance study of self-diffusion in liquid crystals

A simple and accurate pulsed-gradient nuclear magnetic resonance technique for measuring coefficients of self-diffusion in liquid crystals is described. It is based on exciting sharp response signals with long weak pulses. The method uses an extremely weak radio-frequency field, which eliminates the problem of radio-frequency heating of the sample. The temperature dependencies of coefficients of self-diffusion for two liquid crystals, 5CB (4-pentyl-4(')-cyanobiphenyl) and EBBA (N-(4-ethoxybenzylidene)-4-butylaniline), are presented.     

Ox-LDL suppresses PMA-induced MMP-9 expression and activity through CD36-mediated activation of PPAR-g

During chronic inflammatory response, mono- cytes/macrophages produce 92-kDa matrix metalloproteinase-9 (MMP-9), which may contribute to their extravasation, migration and tissue remodeling. Activation of peroxisome proliferator- activated factor receptor-g (PPAR-g) has been shown to inhibit MMP-9 activity. To evaluate whether ox-LDL, a PPAR-g activator, inhibits PMA-induced MMP-9 expression and activity, and if so, whether CD36 and PPAR-g are involved in this process, we investigated the effect of ox-LDL on MMP-9 expression and activity in PMA-activated human monocytic cell line U937. PMA-induced MMP-9 expression and activity were suppressed by the treatment with ox-LDL (50 mg/ml) or PPAR-g activators such as troglitazone (5 mM), ciglitazone (5 mM), and 15d- PGJ2 (1 mM) for 24 h. This ox-LDL or PPAR-g activator-mediated inhibition of MMP-9 activity was diminished by the pre-treatment of cells with a blocking antibody to CD36, or PGF2a (0.3 mM), which is a PPAR-g inhibitor, as well as overexpression of a dominant-negative form of CD36. Taken together, these results suggest that ox-LDL suppresses PMA-induced MMP-9 expression and activity through CD36-mediated activation of PPAR-g.     

Synthesis of blue-light-emitting ZnGa2O4 nanowires using chemical vapor deposition

A high-density array of vertically aligned ZnGa(2)O(4) nanowires has been synthesized on Si substrates via CVD of ZnO-Ga at 1000 degrees C consisting of a single-crystalline cubic spinel structure grown in a [111] direction and exhibiting strong photoluminescence and cathodoluminescence in the blue wavelength region.     

Improved signal-to-noise ratio in spectral-domain compared with time-domain optical coherence tomography

A signal-to-noise ratio (SNR) analysis is presented for optical coherence tomography (OCT) signals in which time-domain performance is compared with that of the spectral domain. A significant SNR gain of several hundredfold is found for acquisition in the spectral domain. The SNR benefit is demonstrated experimentally in a hybrid time-domain-spectral-domain OCT system.