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Search Results: 1 - 10 of 30 matches for " Pornchai Rojsitthisak "
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HPLC-UV, MALDI-TOF-MS and ESI-MS/MS Analysis of the Mechlorethamine DNA Crosslink at a Cytosine-Cytosine Mismatch Pair
Pornchai Rojsitthisak, Nutthapon Jongaroonngamsang, Rebecca M. Romero, Ian S. Haworth
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0020745
Abstract: Background Mechlorethamine [ClCH2CH2N(CH3)CH2CH2Cl], a nitrogen mustard alkylating agent, has been proven to form a DNA interstrand crosslink at a cytosine-cytosine (C-C) mismatch pair using gel electrophoresis. However, the atomic connectivity of this unusual crosslink is unknown. Methodology/Principal Findings HPLC-UV, MALDI-TOF-MS, and ESI-MS/MS were used to determine the atomic connectivity of the DNA C-C crosslink formed by mechlorethamine, MALDI-TOF-MS of the HPLC-purified reaction product of mechlorethamine with the DNA duplex d[CTCACACCGTGGTTC]?d[GAACCACCGTGTGAG] (underlined bases are a C-C mismatch pair) indicated formation of an interstrand crosslink at m/z 9222.088 [M?2H+Na]+. Following enzymatic digestion of the crosslinked duplex by snake venom phosphodiesterase and calf intestinal phosphatase, ESI-MS/MS indicated the presence of dC-mech-dC [mech = CH2CH2N(CH3)CH2CH2] at m/z 269.2 [M]2+ (expected m/z 269.6, exact mass 539.27) and its hydrolytic product dC-mech-OH at m/z 329.6 [M]+ (expected m/z 329.2). Fragmentation of dC-mech-dC gave product ions at m/z 294.3 and 236.9 [M]+, which are both due to loss of the 4-amino group of cytosine (as ammonia), in addition to dC and dC+HN(CH3)CH = CH2, respectively. The presence of m/z 269.2 [M]2+ and loss of ammonia exclude crosslink formation at cytosine N4 or O2 and indicate crosslinking through cytosine N3 with formation of two quaternary ammonium ions. Conclusions Our results provide an important addition to the literature, as the first example of the use of HPLC and MS for analysis of a DNA adduct at the N3 position of cytosine.
Synthesis, Characterization and Biological Evaluation of Succinate Prodrugs of Curcuminoids for Colon Cancer Treatment
Wisut Wichitnithad,Ubonthip Nimmannit,Sumrit Wacharasindhu,Pornchai Rojsitthisak
Molecules , 2011, DOI: 10.3390/molecules16021888
Abstract: A novel series of succinyl derivatives of three curcuminoids were synthesized as potential prodrugs. Symmetrical (curcumin and bisdesmethoxycurcumin) and unsymmetrical (desmethoxycurcumin) curcuminoids were prepared through aldol condensation of 2,4-pentanedione with different benzaldehydes. Esterification of these compounds with a methyl or ethyl ester of succinyl chloride gave the corresponding succinate prodrugs in excellent yields. Anticolon cancer activity of the compounds was evaluated using Caco-2 cells. The succinate prodrugs had IC50 values in the 1.8–9.6 μM range, compared to IC50 values of 3.3–4.9 μM for the parent compounds. Curcumin diethyl disuccinate exhibited the highest potency and was chosen for stability studies. Hydrolysis of this compound in phosphate buffer at pH 7.4 and in human plasma followed pseudo first-order kinetics. In phosphate buffer, the kobs and t1/2 for hydrolysis indicated that the compound was much more stable than curcumin. In human plasma, this compound was able to release curcumin, therefore our results suggest that succinate prodrugs of curcuminoids are stable in phosphate buffer, release the parent curcumin derivatives readily in human plasma, and show anti-colon cancer activity.
Mathematical Model and Experiment of Temperature Effect on Discharge of Lead-Acid Battery for PV Systems in Tropical Area  [PDF]
Boonyang Plangklang, Pornchai Pornharuthai
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.51006

This paper presents Mathematical Model and Experiment of Temperature effect on Charge and Discharge of Lead-Acid Battery performance in PV system power supply. To test temperature effect on battery discharge cycles, a temperature range of tropical area from 25 - 60 degrees Celsius in a simulator is set up for testing. This temperature range is normally practical for battery usage. This allows the battery to determine the parameters of the battery quickly and high accurate. A Mathematical Model with MATLAB Program is written and constructed as block diagram using the equations of battery the parameters. By running program, the effects of various parameters are investigated. The results showed that time of discharge the battery is longer. Then, the experiment is set up by battery VRLA 12 V 20 AH. The results confirmed the mathematical model simulations.

Comparisons of wavelet functions in QRS signal to noise ratio enhancement and detection accuracy
Pornchai Phukpattaranont
Computer Science , 2015,
Abstract: We compare the capability of wavelet functions used for noise removal in preprocessing step of a QRS detection algorithm in the electrocardiogram (ECG) signal. The QRS signal to noise ratio enhancement and the detection accuracy of each wavelet function are evaluated using three measures: (1) the ratio of the maximum beat amplitude to the minimum beat amplitude (RMM), (2) the mean of absolute of time error (MATE), and (3) the figure of merit (FOM). Three wavelet functions from previous well-known publications are explored, i.e., Bior1.3, Db10, and Mexican hat wavelet functions. Results evaluated with the ECG signal from MIT-BIH arrhythmia database show that the Mexican hat wavelet function is better than the others. While the scale 8 of Mexican hat wavelet function can provide the best enhancement in QRS signal to noise ratio, the scale 4 of Mexican hat wavelet function can provide the best detection accuracy. These results may be combined and may enable the use of a single fixed threshold for all ECG records leading to the reduction in computational complexity of the QRS detection algorithm.
Estimation Risk Modeling in Optimal Portfolio Selection: An Empirical Study from Emerging Markets
Sarayut Nathaphan,Pornchai Chunhachinda
Economics Research International , 2010, DOI: 10.1155/2010/340181
Abstract: Efficient portfolio is a portfolio that yields maximum expected return given a level of risk or has a minimum level of risk given a level of expected return. However, the optimal portfolios do not seem to be as efficient as intended. Especially during financial crisis period, optimal portfolio is not an optimal investment as it does not yield maximum return given a specific level of risk, and vice versa. One possible explanation for an unimpressive performance of the seemingly efficient portfolio is incorrectness in parameter estimates called “estimation risk in parameter estimates”. Six different estimating strategies are employed to explore ex-post-portfolio performance when estimation risk is incorporated. These strategies are traditional Mean-Variance (EV), Adjusted Beta (AB) approach, Resampled Efficient Frontier (REF), Capital Asset Pricing Model (CAPM), Single Index Model (SIM), and Single Index Model incorporating shrinkage Bayesian factor namely, Bayesian Single Index Model (BSIM). Among the six alternative strategies, shrinkage estimators incorporating the single index model outperform other traditional portfolio selection strategies. Allowing for asset mispricing and applying Bayesian shrinkage adjusted factor to each asset's alpha, a single factor namely, excess market return is adequate in alleviating estimation uncertainty.
Condition monitoring of valve clearance fault on a small four strokes petrol engine using vibration signals
Songpon Klinchaeam,Pornchai Nivesrangsan
Songklanakarin Journal of Science and Technology , 2010,
Abstract: This paper studies condition monitoring technique of a small four strokes, single cylinder petrol engine using vibrationsignal analysis based on time domain, crank angle domain, and signal energy. Vibration signals are acquired from the cylinderhead of the engine and used to describe engine processes such as intake/exhaust valve operations, ignition process, andcombustion process. In this study, vibration signals have been applied to monitor various fault conditions in the engine suchas intake and exhaust valve clearance faults. Vibration signals acquired in time domain could be mapped onto crank angledomain using top dead center signal. Time domain techniques were used to analyze vibration signals so that the main eventsrelated to the engine operations could be described easily. Using energy analysis technique, all fault conditions could bealso identified. For future work, signal analysis techniques must be developed and the detected signals should be comparedwith other signals such as pressure signal in order to verify the accuracy of the results.
Design of a quadratic filter for contrast - assisted ultrasonic imaging based on 2D gaussian filters
Tosaporn Nilmanee,Pornchai Phukpattaranont
Songklanakarin Journal of Science and Technology , 2010,
Abstract: We present a novel design of quadratic filters (QFs) in the frequency domain in order to improve the quality of contrastassisted ultrasound images for medical diagnosis. The QF is designed as a 2D linear-phase filter. In addition, the magnitude is based on the sum of two 2D Gaussian filters. The centers of the Gaussian filters are placed at the locations where the power strength of signals from ultrasound contrast agent over surrounding tissue is maximal. The design parameters consist of two centers and a standard deviation (SD) of the Gaussian filters. The coefficients of the QF are obtained using the inverse discreteFourier transform. The QFs from the proposed design method are evaluated using in vivo ultrasound data, i.e., the kidney of aguinea pig. We find that the appropriate SD and two center points of the QF for the in vivo data are at 0.34, (3.30, 3.30) and (-3.30,-3.30) MHz, respectively. Results show that the images produced from the output signals of the new design are superior to theoriginal B-mode both in terms of contrast and spatial resolution. The quadratic image provides clear visualization of thekidney shape and large vascular structures inside the kidney. The contrast-to-tissue ratio value of quadratic image is 24.8 dBcompared to -1.5 dB from the B-mode image. In addition, we can use this new design approach as an efficient tool to furtherimprove the QF in producing better contrast-assisted ultrasound images for medical diagnostic purposes.
Chromosome image classification using a two-step probabilistic neural network
Sunthorn Rungruangbaiyok,Pornchai Phukpattaranont
Songklanakarin Journal of Science and Technology , 2010,
Abstract: Chromosome image analysis is composed of image preparation, image analysis, and image diagnosis. General procedureof chromosome image analysis includes of image preprocessing in the first step, image segmentation, feature extraction, andimage classification in the last step. This paper presents the preliminary results that use probabilistic neural network toclassify chromosome image into 24 classes. Features of chromosome which were used in this paper are area, perimeter, band’sarea, singular value decomposition, and band profile. Chromosome images were grouped in two steps by probabilistic neuralnetwork. Six groups and twenty four groups are in the first and the second step, respectively. The result from the secondstep is twenty four chromosome classes. Density profile sampled at 10, 30, 50 and 80 were tested. The best classificationresult of female is 68.19% when density profile at 30 samples was used, and that of male is 61.30% when density profile at50 samples was used.
Performance analysis of linear bandpass filter and pulse inversion in separating subharmonic frequency of signals from ultrasound contrast agent
Chinda Samakee,Pornchai Phukpattaranont
Songklanakarin Journal of Science and Technology , 2012,
Abstract: Recently, many publications reported the generation of subharmonic frequency (f0/2) and its potential use in imagingfrom ultrasound contrast agent (UCA). Subharmonic imaging (SHI) has provided better contrast resolution over the secondharmonic signals due to the lack of subharmonic generation in the tissue region. However, subharmonic separation in SHIutilizes linear bandpass filtering only. In this paper, we compare the subharmonic separation capability of linear band filter(LBF), pulse inversion (PI), and their combination (PILBF) based on contrast-to-tissue ratio (CTR). Results show that theCTR values from the LBF, the PI, and the PILBF are 20.30, 40.30, and 52.74 dB, respectively. The optimal stopband attenuation and fractional bandwidth for the PILBF method are 50 dB and 10%, respectively. This high CTR value indicates thefeasibility of the PILBF method in creating high quality ultrasound image from subharmonic frequency.
Developing Tools for Health Impact Assessment in Environmental Impact Assessment in Thailand
Acta Medica Okayama , 2011,
Abstract: The purpose of this research was to develop tools applicable to the Health Impact Assessment (HIA) in Environmental Impact Assessment (EIA) in a Thai context. The relevant documents and articles were extensively reviewed, analyzed, and drafted. The first draft was presented to a research advisory committee for their review, and the recommended changes were subsequently made. The second draft was then presented to respondents from 6 groups of key stakeholders-expert review committees under the Office of Natural Resources and Environmental Policy and Planning (ONREPP), EIA registered consulting firms, non-government organizations, members of the ONREPP, local government organizations, and government organizations responsible for issuing permission to the proposed projects. Their commentary and recommendation were considered, and modifications were made as necessary. The third draft was finally reviewed by the research advisory committee before the tryout step. The final revised version is presented in this paper.
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