High-resolution Matrix Research Articles

Denaturing HPLC for Identification of Clonal T-Cell Receptor γ Rearrangements in Newly Diagnosed Acute Lymphoblastic Leukemia

Denaturing HPLC (DHPLC) can be used to screen DNA for known and unknown mutations. We describe a novel, HPLC-based method for discrimination among polyclonal, oligoclonal, and/or clonal T-cell receptor gamma (TCR-gamma) rearrangements in samples from children with newly diagnosed acute lymphoblastic leukemia. TCR rearrangements were PCR amplified from initial leukemic samples and, after heteroduplex-induction, the clonality status of each product was evaluated. To attain this, we used DHPLC on a high-resolution micropellicular matrix. Running conditions were established by melting-curve analysis of known clonal and polyclonal products and melting-point prediction software. Elution profiles were studied at 50 degrees C (native) and, to achieve optimal separation, at different column temperatures between 56 and 64 degrees C. For VgammaI-Jgamma1.3/2.3 rearrangements, an analysis temperature of 60 degrees C with a linear triethylammoniumacetate-acetonitrile gradient separated clonal bands from the polyclonal background amplification. Less than 15% clonal PCR product was detectable in mixtures of initial leukemic cell DNA and polyclonal DNA. Biallelic rearrangements produced two sharp peaks. Clonality of PCR products from 100 initial leukemic samples was completely identified in all investigated cases. Heteroduplex analysis with standardized DHPLC conditions simplifies the detection of unknown clonal or polyclonal TCR rearrangements in newly diagnosed leukemias. Clonal targets for detection of minimal residual disease are available after a short, automated analysis of PCR amplified rearrangements.

5.1: Invited Paper: History and Status of Organic Light Emitting Device (OLED) Technology for Vehicular Applications

AbstractWith the drive to convey much more information in today's vehicles to both driver and passenger, organic light emitting device (OLED) technology has begun to capture the attention of automotive systems designers and engineers. OLED displays are bright, emissive devices that offer excellent color gamut, wide viewing angle and high contrast. Passive matrix (PM) monochrome and multi‐color OLEDs have been introduced in products including an automotive audio console and cellular telephone. In the near future, full‐color, high‐resolution active matrix (AM) OLEDs with excellent power efficiency, particularly through the use of new high‐efficiency phosphorescent materials, will also be available. Finally, continued progress toward meeting more rigorous requirements, for thermal stability and extended lifetimes, including those of the automotive environment, are foreseen. Moreover, recent technological advances such as display flexibility and transparency have created exciting new ways to integrate OLEDs into vehicles. In this paper, we discuss the status of OLED technology, highlighting some of the key features and performance measures that are most important to the automotive designer and engineer.

Echo-planar magnetic resonance imaging (EPI) with high-resolution matrix in intra-axial brain tumors.

The aim of this study was to assess the potential of high-speed interleaved echo-planar imaging (EPI) to achieve diagnostic image quality comparable to T2-weighted imaging in patients with brain tumors. Seventeen patients with intra-axial, supratentorial tumors (10 untreated gliomas, 7 radiated gliomas) were investigated on a 1. 5-T scanner. The conventional scan (SE, TR/TE = 2200/80 ms, 18 slices) was acquired in 8 min, 4 s, and EPI (TR/TE = 3000/80 ms, 18 slices) was completed in 25 s. The films were compared in a blinded trail by three radiologists. On the general impression and anatomic display, both sequences were rated to be of similar quality. Artifacts were slightly more pronounced at the skull base and around surgical clips using EPI. Tumor delineation was nearly equivalent using EPI, compared with the T2-weighted sequence. Echo-planar imaging reached diagnostic quality in all patients. Interleaved high-resolution EPI yielded sufficient quality to depict intra-axial, supratentorial brain tumors. Since EPI can be obtained in a small fraction of the time needed for conventional spin echo, in addition to other indications it could be considered to study patients unable to cooperate.

Polymer-Stabilized Ferroelectric Liquid Crystal Devices with Grayscale Memory

A novel grayscale-memory ferroelectric liquid crystal device with polymer dispersion has been studied. The ferroelectric liquid crystal molecules are stabilized by a low-concentration doped polymer, which induces an enormous number of small liquid crystal domains with different threshold voltages for bistable switching. The polydomain has a spatial grayscale effect due to domain distribution. In forming the polymer-dispersion system with phase separation under ultraviolet light irradiation, a solution of liquid crystal and prepolymer was heated at the chiral nematic phase, and the directors of liquid crystal and prepolymer molecules were oriented parallel to the rubbing direction of alignment layers on substrates. A unique microscopic striped texture extending parallel to the rubbing direction was observed at a room temperature, and could be used to form the small domains. The 2-µ m-thick device, fabricated by addition of 4 wt% polymer and strong ultraviolet irradiation of 40 mW/cm2, exhibited excellent grayscale memory according to applied voltage pulses of a few V. It has much potential for use in high-resolution matrix panel displays.

Acute Epicardial ECG Parameters as Quantitative Predictors of Infarct Size at 1 Week in the Baboon

We describe an experimental baboon model that allows quantitative prediction of myocardial necrosis measured at 1 week from acute epicardial ECG parameters recorded from a high-resolution matrix of fixed epicardial electrodes. The electrode grid overlies a circumscribed area of ultimate necrosis, produced by the occlusion of a selected diagonal branch of the left anterior descending coronary artery (LAD). This grid allowed examination of the pattern of changes in ST segment elevation (ST↑) throughout their return to control levels, and profiled changes in the distribution of electrodes recording TQ-ST segment deflections. Those points more centrally located within the area of ST↑ consistently showed greater absolute values of ST↑ and remained elevated longer than the more peripheral electrodes. Areas of the electrode matrix corresponding to those electrode points showing significant ST↑ (2 mV above control) at each recording interval through 8 hr were fitted to the area of necrosis underlying this electrode grid. While the maximum area of ST↑ (maxAst) uniformly overestimated infarct size between animals on the order of 25%, regression analysis allowed prediction of the extent of infarct from maxAst with an error of only 5%. Correlation of maxAst with the epicardial extent of infarct, total weight, and volume yielded coefficients of 0.95, 0.85, and 0.91 respectively, while mean ST↑ (ST↑) showed a poorer correlation with respective coefficients of 0.49, 0.55, and 0.39. MaxAst proved to be the single best predictor of infarct size assessed at 1 week.

Detection of single-nucleotide polymorphisms with the WAVE DNA fragment analysis system.

As the Human Genome Project is generating an avalanche of genetic information, molecular researchers and clinical practitioners are setting new criteria for evaluation of the links between newly discovered gene mutations and human disorders. These requirements necessitate the development of highly accurate and yet rapid automated systems for genetic testing. We describe the detection of a single nucleotide polymorphism (SNP) on the human Y chromosome with the fully automated, sensitive, and rapid system WAVE designed for DNA fragment analysis. This new technology, based on temperature-modulated liquid chromatography and a high-resolution matrix, offers new dimensions to the molecular biology research. The versatility of the WAVE makes the equipment a universal molecular biology stations for clinical and research facilities. The key aspects to setting the operating parameters are discussed.

The Use of Osazones as Matrices for the Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry of Carbohydrates

Fifteen sugar osazones were synthesized and evaluated for their use as matrix-assisted laser desorption/ionization matrices. Various carbohydrate samples were analyzed, indicating thatd- orl-arabinosazone, prepared fromd- orl-arabinose and phenylhydrazine, gave the overall best performance. The arabinosazones facilitated superior analyses in providing a highly uniform distribution of sample molecules within the matrix microcrystals, and a possibility of using low laser energy for irradiation, leading to high spectral resolution and low matrix background. The arabinosazones with a moderate content of sodium ions promoted specific fragmentation for certain carbohydrates tested. The 50 fmol amounts of maltohexaose and maltoheptaose (present in 0.1 μl of sample/matrix solution) were detected at a signal-to-background ratio of 3:1.

Image technique optimization in MR imaging of a titanium alloy joint prosthesis.

The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at I.O.T. The SE imaging parameters were bandwidth/pixel(BW/ p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256-512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique.

Optimum tomographic reconstruction parameters for HMPAO brain SPET imaging: a practical approach based on subjective and objective indexes.

The purpose of this study was to define an optimal strategy for the tomographic reconstruction procedure in routine brain single-photon emission tomography (SPET) studies, including the number of projections, filter function and matrix size. A set of projection data with different count densities was obtained from a technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) brain SPET acquisition from one volunteer. The projections were reconstructed with different filters and the quality of the reconstructed images was determined using both a subjective observer rating score and the Gilbert index. For each count density, the observers' choice corresponded to images with the lowest Gilbert index. The noise level in brain SPET sections was estimated and correlated with the fractal dimension. The results of this study indicate that although noise represents a fundamental component of brain SPET imaging, image quality also depends on the reconstructed spatial resolution. Image quality is satisfactorily described by fractal dimension. In addition the optimal filter function depends on the available count density. For high count levels, optimal reconstruction may be obtained by using a high-resolution matrix and a slightly smoother reconstruction filter. When count densities are low, best results are obtained by using a low-resolution matrix and a sharper filter. Finally, this study suggests that image quality is not influenced by the number of projections for equivalent count densities. These results were confirmed by 30 HMPAO brain SPET studies acquired in a routine clinical setting.

Zero-phonon line as the foundation stone of high-resolution matrix spectroscopy, persistent spectral hole burning, single impurity molecule spectroscopy

The purely electronic zero-phonon line (ZPL) - the optical analog of the Mössbauer-γ-resonance line - is a remarkable feature of the low temperature impurity absorption and luminescence spectra of solids. The narrowness and high peak absorption cross section of ZPLs has opened new horizons for high resolution spectroscopy of impurity molecules (centers). The newest and most spectacular achievement is single impurity molecule spectroscopy. Persistent spectral hole burning (PSHB), serving as a tool to control by means of illumination the absorption coefficient, and bound to it, via the Kramers-Kronig relations, the refraction index, turns inhomogeneous broadening of ZPLs into a useful feature and opens a variety of applications including PSHB optical data storage and processing. Space-frequency and space-time domain holographies are developed. The latter comprises the causality relations between events subject to holography and opens new principal possibilities in optics.

High resolution infrared spectroscopy of deuterium in p-H2 matrix

The high resolution spectrum of the fundamental band of deuterium impurity embedded in solid parahydrogen has been studied using a difference frequency laser spectrometer. This observation represents the first case of high resolution matrix spectroscopy in solid hydrogen. Both the Q1←0(0) and Q1←0(1) transitions were resolved into sharp features with a typical linewidth of ≲ 10 MHz, while both the S1←0(0) and S1←0(1) transitions appeared to be much broader with widths of ∼0.07 cm−1. A discussion of the linewidths based on homogeneous broadening is presented.

Hochauflösende MR-Tomographie der Hand: Normalanatomie

By using surface coils and a high resolution matrix, the images from MR tomography of small objects can be greatly improved. Normal subjects have been examined in order to demonstrate the usefulness of MR tomography for the examination of bones and soft tissues in the normal hand.

Effect of left ventricular-to-aortic bypass on infarct size and infarct microcirculation in baboons

A major diagonal branch of the left anterior descending coronary artery (LAD) was acutely occluded in 17 baboons. Complete left ventricular (LV) decompression was achieved with a left heart bypass (LHB) system in six baboons while 11 baboons served as untreated controls. In the treated group, LHB was initiated after 30 minutes of coronary occlusion. For a period of 6 hours after occlusion, aortic pressure, LV pressure, left atrial pressure, and cardiac output were monitored. During the same monitoring period, electrograms were recorded from a high resolution matrix of fixed epicardial electrodes. Regional myocardial blood flow was determined prior to and at intervals following the initiation of LHB with radioactive microspheres. Infarct size was assessed histologically from serial cross sections of the left ventricle. The degree of salvage achieved by LHB was assessed by comparing the epicardial area of infarction 6 hours after occlusion (AI) to the area of epicardial St-segment elevation (STE) 30 minutes after occlusion (maxAST). In the LHB-treated group, 40.0% +/- 8.1% (SEM) of maxAST showed subsequent infarction; in the control group, 79.8% +/- 2.7% of maxAST showed eventual infarction (p less than 0.01). STE overlying the region of ischemia in the LHB-treated group did not undergo the spontaneous decline observed in the control group, which is normally associated with the progression of necrosis. Regional myocardial blood flow did not change significantly in the ischemic region during the period of occlusion following LHB. LHB. The results suggest that LHB is capable of substantial salvage of acutely ischemic myocardium by reducing myocardial work and thus reducing myocardial oxygen requirements.

High resolution led displays for avionic applications

The rapidly increasing complexity of avionic systems and the decrease in space available for bulky crt based display systems requires a more compact display technology in many applications. This paper describes the initial development and use of red monolithic light emitting diodes in avionic systems. It is shown that common cathode displays are capable of meeting most standby sight and fixed format helmet mounted display requirements. In addition the development of high resolution matrix addressable arrays is described.

Epicardial mapping and electrocardiographic models of myocardial ischemic injury.

The amplitude and distribution of epicardial ST-segment elevation (ST) were examined for an 8-hour period after coronary occlusion in eight baboons and five pigs. ST was determined from unipolar epicardial electrograms obtained from a high-resolution matrix of fixed electrodes overlying a transmural region of ischemia. A relatively uniform degree of ST was observed overlying the ischemic region for 20 minutes after coronary occlusion. A gradient in ST from the periphery to the center of the ischemic region was documented after 20 minutes of ischemia. In 10 other pigs, change in the degree of ST was examined contingent on either an increase (five pigs) or decrease (five pigs) in the size of the ischemic region after 1 hour of preexisting ischemia. An abrupt increase in the number of electrodes that showed ST (NST) from 7.8 +/- 1.24 (SEM) to 14.8 +/- 1.35 (90%) was associated with an increase in mean ST of 58% from 4.28 +/- 0.61 mV to 6.78 +/- 0.84 (p less than 0.05). An abrupt decrease in NST from 25.2 +/- 2.63 to 14.6 +/- 2.22 (42%) was associated with a decrease in mean ST of 24%, from 8.2 +/- 0.36 mV to 6.3 +/- 0.30 mV (p less than 0.01). The results during early ischemia (less than 20 minutes of ischemia) are accurately represented by a model of ischemia in which injury current arises only at the ischemic boundary. The results during later ischemia (after 20 minutes of ischemia) may be represented by a model in which ST is considered dependent on injury currents generated throughout the ischemic region.