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Huai Krachao, Thailand

Leetachewa S.,Mahidol University | Moonsom S.,Mahidol University | Chaisri U.,Mahidol University | Khomkhum N.,Mahidol University | And 3 more authors.
BMB Reports

The insecticidal activity of Bacillus thuringiensis (Bt) Cry toxins involves toxin stabilization, oligomerization, passage across the peritrophic membrane (PM), binding to midgut receptors and pore-formation. The residues Arg-158 and Tyr-170 have been shown to be crucial for the toxicity of Bt Cry4Ba. We characterized the biological function of these residues. In mosquito larvae, the mutants R158A/E/Q (R158) could hardly penetrate the PM due to a significantly reduced ability to alter PM permeability; the mutant Y170A, however, could pass through the PM, but degraded in the space between the PM and the midgut epithelium. Further characterization by oligomerization demonstrated that Arg-158 mutants failed to form correctly sized high-molecular weight oligomers. This is the first report that Arg-158 plays a role in the formation of Cry4Ba oligomers, which are essential for toxin passage across the PM. Tyr-170, meanwhile, is involved in toxin stabilization in the toxic mechanism of Cry4Ba in mosquito larvae. © 2014 by the The Korean Society for Biochemistry and Molecular Biology. Source

Pongpom M.,Chiang Mai University | Sawatdeechaikul P.,Chiang Mai University | Kummasook A.,Western University of Thailand | Khanthawong S.,Naresuan University | Vanittanakom N.,Chiang Mai University
Medical Mycology

Penicillium marneffei is a significant opportunistic fungal pathogen in Southeast Asia and its ability to survive inside the host macrophages is believed to be important in the establishment of infection. Previously, we isolated a gene encoding a catalase- peroxidase (cpeA) from P. marneffei and showed that the cpeA transcript is specifically upregulated during yeast phase growth at 37°C. In this study, the cpeA transcript was found to be induced during the mycelium to yeast phase transition and during stress conditions induced by hydrogen peroxide treatment. Null mutation of cpeA reduced the fungal tolerance to hydrogen peroxide but not to heat stress. These results indicated that the CpeA plays a crucial role in this fungus' oxidative stress response. Western blot analysis demonstrated that the CpeA induced antibody production in P. marneffei-infected patients, including highly exposed-healthy people. This is the first report that the catalase-peroxidase possesses an immunogenic property in fungi. © 2013 ISHAM. Source

Gichki A.S.,Bolan Medical College | Buajeeb W.,Mahidol University | Doungudomdacha S.,Western University of Thailand | Khovidhunkit S.P.,Mahidol University
Asian Pacific Journal of Cancer Prevention

Human papillomaviruses (HPVs) remain a serious world health problem due to their association with cervical and head and neck cancers. While over 100 HPV types have been identified, only a few subtypes are associated with malignancies. HPV 16 and 18 are the most prevalent oncogenic types in head and neck cancers. Although it has been proven that some subsets of benign and malignant head and neck lesions are associated with HPV, the general population have very little awareness and knowledge of their association with HPV. Therefore, the purpose of this study was to determine the knowledge of HPV and its links with head and neck benign and malignant lesions in a group of Pakistani dental patients who attended the Dental Department of the Sandeman provincial hospital in Quetta, Pakistan. One hundred and ninety-two patients were recruited and requested to answer a questionnaire. It was revealed that there was a low level of knowledge about HPV and its association with head and neck benign and malignant lesions among the participants. This result suggested that more education regarding the relationship of HPV in inducing head and neck benign and malignant lesions is required in this group of patients. Source

Kreetachat T.,University of Phayao | Kruenate J.,National Metal and Materials Technology Center | Suwannahong K.,Western University of Thailand
Applied Mechanics and Materials

Biodegradable of polylactic acid (PLA), polybutylene adipate-co-terephthalate (PBAT) and polybutylene succinate (PBS), which were biodegradable aliphatic polyesters, composite films were contained with titanium dioxide (TiO2) as a photocatalyst to evaluate the photocatalytic activity of bidegradable composite films for toluene removal. The synthesized TiO2 was prepared by sol-gel method between titanium isopropoxide with acetic acid. To form the anatase structure, it was calcined at 500oC. TiO2 were added to PLA/PBAT/PBS as a biopolymer blend at 0, 5 and 10 wt%.The TiO2/Bio-composite films were fabricated via blown film technique to produce 40 μm films. Photocatalytic activity efficiency of TiO2/Bio-composite films was performed in an annular closed system under UV light. Since the amount of TiO2 affected the efficiency of the photocatalytic activity, this work was mainly concentrated on the effort to embed the high amount of TiO2 in the biopolymer matrix. The developed photocatalyst was characterized by XRD, UV-Vis spectrophotometer and SEM. The SEM images revealed the high homogeneity of the deposition of TiO2 on the biopolymer matrix. The X-ray diffraction (XRD) ensures the deposition of TiO2 as crystalline anatase phase. In addition, the photocatalytic results shown that the toluene removal efficiencies increased with an increasing TiO2 dosages at 0 wt%, 5 wt%, and 10 wt%, respectively. As aspects, the photocatalytic degradation results showed the highest tolune photocatalytic degradation efficiency of 52.0% at 10 wt% TiO2. © (2013) Trans Tech Publications, Switzerland. Source

Kanoksilapatham W.,Silpakorn University | Keawram P.,Silpakorn University | Keawram P.,Western University of Thailand | Gonzalez J.M.,IRNAS CSIC | Robb F.T.,University of Maryland, Baltimore

A hyperthermophilic Thermotoga sp. strain PD524 was isolated from a hot spring in Northern Thailand. Cells were long-curved rods (0.5–0.6 × 2.5–10 μm) surrounded by a typical outer membrane toga. Strain PD524 is aero-tolerant at 4 °C but is aero-sensitive at 80 °C. A heat resistant subpopulation was observed in late-stationary phase. Cells from late-stationary phase were revealed remarkably less sensitive to 0.001 % SDS treatment than cells from exponential phase. The temperature range for growth was 70–85 °C (opt. temp. 80 °C), pH range was 6–8.5 (opt. pH 7.5–8.0), and NaCl range of 0 to <10 g/L (opt. 0.5 g/L). Glucose, sucrose, maltose, fructose, xylose, mannose, arabinose, trehalose, starch, and cellobiose were utilized as growth substrates. Growth was inhibited by So. Growth yield was stimulated by SO4= but not by S2O3= and NO3−. Analysis of 16SrRNA gene sequence (KF164213) of strain PD524 revealed closest similarity (96 %) to Thermotoga maritima MSB8T, T. neapolitana NEST, T. petrophila RKU-1T, and T. naphthophila RKU-10T. © 2015, Springer Japan. Source

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