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    PublicationOpen Access
    Chaotropic effect in reversed-phase HPLC: A review
    (2010) C.M. Phechkrajang; Chutima (Matayatsuk)Phechkrajang; ชุติมา(มัธยัสถ์สุข)เพ็ชรกระจ่าง; Mahidol University. Faculty of Pharmacy. Department of Pharmaceutical Chemistry
    Some inorganic anions such as BF4-, CF3COO-, ClO4-, and H2PO4-, can affect the solubility of proteins and amino acids. Their effects were observed since 1888 by Fran Hofmeister. During the past decade, these ions have been used increasingly in reversed-phase high-performance liquid chromatography (HPLC), because of their abilities to improve the retention of basic substances in their protonated forms without changing a new column or mobile phase pH. Moreover, addition of these ions in mobile phase can improve theoretical plate number and tailing factor as well.
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    PublicationOpen Access
    Comparison of several diffusion equations in the calculation of viscosity and its relation to dissolution rate
    (1982) Narong Sarisuta; Parrott, Eugene L.; ณรงค์ สาริสุต; Mahidol University. College of Pharmacy
    equation. The dissolution rates of benzoic acid in aqueoud solutions of three non-ionic suspending agents is related to the viscosity.
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    PublicationOpen Access
    Aedesin: structure and antimicrobial activity against multidrug resistant bacterial strains.
    (2014-08-27) Godreuil, Sylvain; Leban, Nadia; Padilla, Andre´; Hamel, Rodolphe; Natthanej Luplertlop; นัฏฐเนศวร์ ลับเลิศลบ; Chauffour, Aure´ lie; Vittecoq, Marion; Hoh, Franc¸ois; Thomas, Fre´de´ ric; Sougakoff, Wladimir; Lionne, Corinne; Yssel, Hans; Misse, Dorothe´e; Misse, Dorothe´e; Mahidol University. Faculty of Tropical Medicine. Department of Microbiology and Immunology.
    that it is active under physiological conditions encountered in body fluids characterized by ionic salt concentrations. In conclusion, because of its strong lytic activity against multidrug resistant Gram-negative bacterial strains displaying all types
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    ItemOpen Access
    Study on the aggregation states of Amphotericin B with Raman spectroscopy and UV-vis spectroscopy
    (2019) Nang Sa Lwae; Nattawut Charoenthai; Satit Puttipipatkhachorn; ณัฐวุฒิ เจริญไทย; สาธิต พุทธิพิพัฒน์ขจร; Mahidol University. Faculty of Pharmacy. Department of Manufacturing Pharmacy
    -vis spectroscopy. At low concentrations ranging from 1 x 10-5 M to 1 x 10-7 M, UV-vis spectroscopy could detect the molecular states of AmB as soluble oligomer, and a monomer at maximum wavelength around 325 nm and 408 nm, respectively. However, UV...-vis spectroscopy could not be used to study the molecular states of AmB at higher concentrations. On the other hand, Raman spectroscopy could detect remarkable intense peaks relating to molecular structure of AmB at higher concentrations. Heat
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    PublicationOpen Access
    Combining electrochemical sensors with miniaturized sample preparation for rapid detection in clinical samples
    (2014-11-21) Natinan Bunyakul; Antje J. Baeumner; Mahidol University. Faculty of Medical Technology. Department of Clinical Chemistry
    Clinical analyses benefit world-wide from rapid and reliable diagnostics tests. New tests are sought with greatest demand not only for new analytes, but also to reduce costs, complexity and lengthy analysis times of current techniques. Among the myriad of possibilities available today to develop new test systems, amperometric biosensors are prominent players-best represented by the ubiquitous amperometric-based glucose sensors. Electrochemical approaches in general require little and often enough only simple hardware components, are rugged and yet provide low limits of detection. They thus offer many of the desirable attributes for point-of-care/point-of-need tests. This review focuses on investigating the important integration of sample preparation with (primarily electrochemical) biosensors. Sample clean up requirements, miniaturized sample preparation strategies, and their potential integration with sensors will be discussed, focusing on clinical sample analyses.
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    PublicationOpen Access
    Enzymatic analysis of recombinant Japanese encephalitis virus NS2B(H)-NS3pro protease with fluorogenic model peptide substrates
    (2012-05) Muhammad Junaid; Chakard Chalayut; Anna Sehgelmeble Torrejon; Chanan Angsuthanasombat; Iryna Shutava; Maris Lapins; Jarl E. S. Wikberg; Gerd Katzenmeier; Mahidol University. Institute of Molecular Biosciences. Laboratory of Molecular and Cellular Microbiology
    Background Japanese encephalitis virus (JEV), a member of the Flaviviridae family, causes around 68,000 encephalitis cases annually, of which 20–30% are fatal, while 30–50% of the recovered cases develop severe neurological sequelae. Specific antivirals for JEV would be of great importance, particularly in those cases where the infection has become persistent. Being indispensable for flaviviral replication, the NS2B-NS3 protease is a promising target for design of anti-flaviviral inhibitors. Contrary to related flaviviral proteases, the JEV NS2B-NS3 protease is structurally and mechanistically much less characterized. Here we aimed at establishing a straightforward procedure for cloning, expression, purification and biochemical characterization of JEV NS2B(H)-NS3pro protease. Methodology/Principal Findings The full-length sequence of JEV NS2B-NS3 genotype III strain JaOArS 982 was obtained as a synthetic gene. The sequence of NS2B(H)-NS3pro was generated by splicing by overlap extension PCR (SOE-PCR) and cloned into the pTrcHisA vector. Hexahistidine-tagged NS2B(H)-NS3pro, expressed in E. coli as soluble protein, was purified to >95% purity by a single-step immobilized metal affinity chromatography. SDS-PAGE and immunoblotting of the purified enzyme demonstrated NS2B(H)-NS3pro precursor and its autocleavage products, NS3pro and NS2B(H), as 36, 21, and 10 kDa bands, respectively. Kinetic parameters, Km and kcat, for fluorogenic protease model substrates, Boc-GRR-amc, Boc-LRR-amc, Ac-nKRR-amc, Bz-nKRR-amc, Pyr-RTKR-amc and Abz-(R)4SAG-nY-amide, were obtained using inner filter effect correction. The highest catalytic efficiency kcat/Km was found for Pyr-RTKR-amc (kcat/Km: 1962.96±85.0 M−1 s−1) and the lowest for Boc-LRR-amc (kcat/Km: 3.74±0.3 M−1 s−1). JEV NS3pro is inhibited by aprotinin but to a lesser extent than DEN and WNV NS3pro. Conclusions/Significance A simplified procedure for the cloning, overexpression and purification of the NS2B(H)-NS3pro was established which is generally applicable to other flaviviral proteases. Kinetic parameters obtained for a number of model substrates and inhibitors, are useful for the characterization of substrate specificity and eventually for the design of high-throughput assays aimed at antiviral inhibitor discovery.
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    PublicationOpen Access
    การศึกษาระยะเวลาที่เหมาะสมในการเก็บสารละลายมาตรฐานฟลูออไรด์
    (2559) พชร รุทระกาญจน์; พีรพงษ์ ตัวงาม; Pachara Rudrakanjana; Peerapong Tua-Ngam; มหาวิทยาลัยมหิดล. คณะทันตแพทยศาสตร์. งานประยุกต์ผลงานวิจัย
    of standard fluoride solutions with fluoride concentrations of 0.1, 1.0 and 10.0 ppm The solutions were stored at 4oC for a total of 9 weeks and the average fluoride content of each solution was checked on a weekly basis using Selective Electrode method.... Freshly prepared fluoride solution was used to make control calibration curves and compared with the stored samples at different durations. Data analysis was done using SPSS version 16. Results: In this study the fluoride concentration of 0.1, 1
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    PublicationOpen Access
    Responses of primary human nasal epithelial cells to EDIII-DENV stimulation: the first step to intranasal dengue vaccination
    (2016) Nattika Nantachit; Panya Sunintaboon; Sukathida Ubol; Mahidol University. Faculty of Science. Department of Microbiology
    responses. Results: At tested concentrations, EDIII-D3 TMC NPs not only exerted no detectable toxicity toward HNEpC cultures but also efficiently delivered EDIII-D3 immunogens into HNEpCs. Moreover, HNEpCs quickly and strongly produced proinflammatory
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    PublicationOpen Access
    Comparison and optimization of chromatographic conditions for separation of cyclic analogues of Dynorphin A from linear by-products
    (1997) Leena Leelasvatanakij; ลีณา ลีลาศวัฒนกิจ; Seksiri Arttamangkul; เสกสิริ อาตมางกูร; Aldrich, Jane V.
    In this study, chromatographic conditions for the separation of the lactam analogue of dynorphin A (Dyn A)(1-13)NH2 cyclo[D-Asp(2),Orn(5)]Dyn A(1-13)NH2 from the tetramethylguanidinium by-product [D-Asp(2),Orn(Tmg)(5)]Dyn A(1-13)NH2 and linear peptide [D-Asp(2),Orn(5)]Dyn A(1-13)NH2 were compared. The by-product was obtained following the cyclization of the peptides with 2-(1-H-benzotriazo-1-yl)-1,1,3,3tetramethyluronium hexafluorophosphate. Two methods of high performance liquid chromatography, reverse phase and ion-exchange chromatography, were examined. A number of factors affected the resolutionand the elution profile of peptides, including the ion-pairing agent, the mobile phase pH and the organic solvent. These factors were varied to obtain optimum separation.
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    PublicationOpen Access
    Kinetic Adsorption of Hazardous Methylene Blue from Aqueous Solution onto Iron-Impregnated Powdered Activated Carbon
    (2019) Athit Phetrak; Sirirat Sangkarak; Sumate Ampawong; Suda Ittisupornrat; Doungkamon Phihusut; Mahidol University. Faculty of Tropical Medicine. Department of Social and Environmental Medicine; Mahidol University. Faculty of Tropical Medicine. Department of Tropical Pathology; Department of Environmental Quality Promotion. Environmental Research and Training Center; Chulalongkorn University. Environmental Research Institute
    In this study, iron-impregnated powderedactivated carbon (Fe-PAC) prepared using chemical co-precipitation techniques was used as an adsorbent for methylene blue (MB) removal in a batch experiment. The analysis of transmission electron microscopy, scanning electron microscopy with energy dispersive spectroscopy showed that iron oxide particle was substantially distributed into the surface of the adsorbent, suggesting that Fe-PAC was successfully synthesized. The results showed that fast and efficient adsorption of MB by Fe-PAC was achieved, witha relative short contact time of 10 min and MB adsorption capacity of 51 mg/g. The kinetic adsorption of MB on Fe-APC adsorbent was well described by a pseudo-second-order model. Concurrently, the analysis of intraparticle diffusion model suggests that intraparticle diffusion is not the only rate-limiting step of MB molecules adsorption by Fe-PAC adsorbent. The elevated temperature conditions also improved the removal efficiency of MB. Thermodynamic parameters exhibited by the MB adsorption process onto Fe-PAC were endothermic and spontaneous. The findings of the present work indicate that Fe-PAC can be a potentially effective adsorbent for MB removal in wastewater due to its fast and efficient MB adsorption, and separation in wastewater treatment systems.