排序方式: 共有24条查询结果,搜索用时 15 毫秒
1.
Six flavonoids, five of them novel, have been isolated from the whole stem of Popowia cauliflora and identified as: baicalein trimethyl ether, 5-hydroxy-6,7-dimethoxyflavone, 5,7,8-trimethoxyflavanone, 2′-hydroxy-3′,4′,6′-trimethoxychalcone, 2′,3′,4′,6′-tetramethoxychalcone and 2′,4-dihydroxy-3′,4′,6′-trimethoxychalcone, on the basis of spectral data and simple chemical modifications. The value of 13C NMR in assigning the positions of methoxy substituents is briefly discussed. 相似文献
2.
Bilayer films prepared by the lamination of fish gelatin film (GF) and its corresponding emulsified film (EF) with different thickness ratios (7:3, 5:5 and 3:7) were characterized. Bilayer films had the similar tensile strength (TS) to EF (p > 0.05) but showed lower elongation at break (EAB) (p < 0.05). All bilayer films showed the lower water vapor permeability (WVP) but higher oxygen permeability (OP) than GF. Bilayer films had varying ΔE* (total color different), where the highest value was observed in that laminated with higher thickness ratio of EF (p < 0.05). Lower light transmission and higher transparency value were obtained for bilayer films, compared to GF (p < 0.05). Based on scanning electron microscopic (SEM) cross-section micrographs, all bilayer films consisted of two layers. Differential scanning calorimetric (DSC) analysis revealed that the bilayer films had the higher glass transition temperature (T g) than GF but lower than EF. All bilayer films were heat sealable, however their seal strength and seal efficiency were lower than those of GF (p < 0.05). Therefore, the thickness ratios of GF and EF had a marked effect on the mechanical and barrier properties as well as heat sealing ability of resulting bilayer films. 相似文献
3.
Arihiro Osanai Sheng‐Jun Li Krisana Asano Hiroshi Sashinami Dong‐Liang Hu Akio Nakane 《Microbiology and immunology》2013,57(4):253-262
The role of fibronectin binding protein A (FbpA) in Listeria monocytogenes infection and its pathogenesis were studied in vivo and in vitro by constructing a fbpA‐deficient mutant of L. monocytogenes (ΔfbpA). In vivo, ΔfbpA was less pathogenic in mutant mice than was wild‐type L. monocytogenes. FbpA did not affect the amounts of various virulence‐determining factors, including internalin B and listeriolysin O. However, adherence to, and invasion of, mouse hepatocytes by the ΔfbpA mutant were reduced. In contrast, adherence to, but not invasion of, the ΔfbpA mutant to macrophages was attenuated. Fibronectin contributed to the efficient adherence and invasion of wild‐type L. monocytogenes, but not to those of the ΔfbpA mutant. Attenuation of adhesion and uptake of the ΔfbpA mutant were reversed by overexpression of FbpA in it. FbpA was not involved in intracellular growth, autophagy induction or actin tail formation. Thus, the present findings clearly show that FbpA acts as an important adhesion molecule of L. monocytogenes, especially regarding hepatocytes, without modulating the expression of other virulence factors that have been implicated in the pathogenesis of L. monocytogenes infection. 相似文献
4.
Phucharoen K Hoshino K Takenaka Y Shinozawa T 《Bioscience, biotechnology, and biochemistry》2002,66(5):955-962
An alkali- and halo-tolerant bacterium with high catalase activity was isolated and identified as a new species of the genus Halomonas. Its catalase (HktA) was simply purified by two steps of liquid chromatography. A 71.4% yield of the catalase was obtained with 97% purity on SDS-PAGE. The specific activity of HktA (57,900 U/mg protein) was two times higher than that of bovine liver catalase. The purified enzyme is inhibited by KCN, NH2OH, NaN3, and 3-amino-1,2,4-triazole, active at pH 5.0-11.0, thermo-sensitive, and KCl-tolerant. HktA is suggested to be a typical catalase, a homotetrameric protein containing heme groups in the active sites. The nucleotide sequence of the catalase gene (hktA) comprises 1,530 bp, encoding a protein of 509 amino acid residues. The deduced amino acid sequence of the hktA shares 99% identity with that of Vibrio rumoiensis S-1T. 相似文献
5.
珊瑚礁生态脆弱性评价——以泰国思仓岛为例 总被引:1,自引:0,他引:1
珊瑚礁生态系统受到环境变化、人类活动等各种因素的严重威胁,保护珊瑚礁生态系统是目前全球海洋生态保护的热点,对珊瑚礁开展定量的生态脆弱性评估能够为保护管理对策的制定提供重要科学依据。本研究选取泰国思仓岛作为研究区域,结合空间分析技术建立了具有通用性的珊瑚礁生态脆弱性评估方法。基于ESA模型构建了珊瑚礁生态脆弱性综合指数和评价指标体系,系统分析了思仓岛珊瑚礁脆弱性的来源、构成,并直观展现了脆弱性的区域空间分布。结果表明:思仓岛研究区东北侧的珊瑚礁生态脆弱性大于西南侧,当地珊瑚礁的关键影响因子分别为驳船排污、港口码头、水体透明度等。根据脆弱性评价的结果,提出了当地珊瑚礁保护与修复的空间分区管理对策。本研究为印度-太平洋区系珊瑚礁生态脆弱性评价提供了可行的示例,也为中国的珊瑚礁可持续管理研究提供了借鉴和参照。 相似文献
6.
Kotchakorn JuntapramNalena Praphairaksit Krisana SiraleartmukulNongnuj Muangsin 《Carbohydrate polymers》2012,87(4):2399-2408
Two mucoadhesive thiolated polymers were synthesized by the covalent attachment of homocysteine thiolactone (HT) to chitosan and N,N,N-trimethyl-chitosan (TM-chitosan) at various chitosan:HT ratios. The amount of thiol and disulphide groups immobilized on the chitosan influenced the polymer's mucoadhesion positively and negatively, respectively, with the optimal chitosan:HT (w/w) ratio being found to be 1:0.1. The interaction between mucin and chitosan and its three derivatives was highest for the thiolated chitosan derivatives but was pH dependent. HT-chitosan and TM-HT-chitosan, with the thiol groups of 64.15 and 32.48 μmol/g, respectively, displayed a 3.67- and 6.33-fold stronger mucoadhesive property compared to that of the unmodified chitosan at pH 1.2, but these differences were only ∼1.7-fold at pH 6.4. The swelling properties of TM-HT-chitosan and HT-chitosan were higher than that of chitosan and TM-chitosan, attaining a swelling ratio of up to 240% and 140%, respectively, at pH 1.2 within 2 h. 相似文献
7.
Sirivichayakul C Limkittikul K Chanthavanich P Jiwariyavej V Chokejindachai W Pengsaa K Suvannadabba S Dulyachai W Letson GW Sabchareon A 《PLoS neglected tropical diseases》2012,6(2):e1520
Background
Dengue infection is one of the most important mosquito-borne diseases. More data regarding the disease burden and the prevalence of each clinical spectrum among symptomatic infections and the clinical manifestations are needed. This study aims to describe the incidence and clinical manifestations of symptomatic dengue infection in Thai children during 2006 through 2008.Study Design
This study is a school-based prospective open cohort study with a 9,448 person-year follow-up in children aged 3–14 years. Active surveillance for febrile illnesses was done in the studied subjects. Subjects who had febrile illness were asked to visit the study hospital for clinical and laboratory evaluation, treatment, and serological tests for dengue infection. The clinical data from medical records, diary cards, and data collection forms were collected and analyzed.Results
Dengue infections were the causes of 12.1% of febrile illnesses attending the hospital, including undifferentiated fever (UF) (49.8%), dengue fever (DF) (39.3%) and dengue hemorrhagic fever (DHF) (10.9%). Headache, anorexia, nausea/vomiting and myalgia were common symptoms occurring in more than half of the patients. The more severe dengue spectrum (i.e., DHF) had higher temperature, higher prevalence of nausea/vomiting, abdominal pain, rash, diarrhea, petechiae, hepatomegaly and lower platelet count. DHF cases also had significantly higher prevalence of anorexia, nausea/vomiting and abdominal pain during day 3–6 and diarrhea during day 4–6 of illness. The absence of nausea/vomiting, abdominal pain, diarrhea, petechiae, hepatomegaly and positive tourniquet test may predict non-DHF.Conclusion
Among symptomatic dengue infection, UF is most common followed by DF and DHF. Some clinical manifestations may be useful to predict the more severe disease (i.e., DHF). This study presents additional information in the clinical spectra of symptomatic dengue infection. 相似文献8.
New insulating particleboards prepared from mixture of solid wastes from tissue paper manufacturing and corn peel 总被引:1,自引:0,他引:1
Lertsutthiwong P Khunthon S Siralertmukul K Noomun K Chandrkrachang S 《Bioresource technology》2008,99(11):4841-4845
New composite boards with low-thermal conductivity produced from a mixture of solid wastes from tissue paper manufacturing (solid waste TPM) and corn peel have been developed. The effects of solid waste TPM/corn peel ratio on the properties of the boards were investigated and the possibility of using recycled polystyrene packaging foam as a laminating agent to improve the quality of the boards was also evaluated. Our results show that the density of the particleboards decrease with increasing the amount of corn peel added in the mixture, leading to a decrease in thermal conductivity of the final product. In contrary, larger amount of solid waste TPM added in the mixture produced stronger boards. The lamination of recycled polystyrene on the surface of particleboards improves the mechanical properties and reduces the thickness swelling of the boards. The best improvement in mechanical properties and swelling resistance could be achieved when 15% polystyrene (w/v) was coated on the surface of the boards. 相似文献
9.
Tossaton Charoonratana Thanapat Songsak Chaowalit Monton Worawan Saingam Kingkan Bunluepuech Jirapornchai Suksaeree Apirak Sakunpak Krisana Kraisintu 《Phytochemistry Reviews》2014,13(2):511-524
The health benefits of herbs and herbal products are gaining more attention in southeast Asia. The World Health Organization (WHO) has been supporting countries to promote application of traditional medicines so that this valuable resource is utilized safely and effectively. In Thailand, many traditional herbal recipes have been established since ancient times. Since then, they have been carefully modified, based on the wisdom of traditional Thai medicine practitioners. For this study, a traditional Thai antihypertensive herbal recipe (TTAH) was selected and studied in detail. According to WHO guidelines, both analysis of a sizeable chemical constituent, and formulation data of a product, are a requirement to support a clinical trial for an herbal recipe. Therefore, high-performance liquid chromatography–mass spectrometry (LC–MS) was used to investigate the chemical fingerprints, chemical constituents, and putative active ingredients of the TTAH. Eight chemical fingerprints were established. Metabolic profiling of 10 possible compounds was also identified and all were shown to be active pharmaceutical compounds. An attempt was also made to prepare a suitable formulation of the TTAH, to standardize the amount of active ingredients per dose, and to improve patient compliance. All evaluated parameters guided us to prepare the TTAH as a capsule. This informative data can be included in part of the chemistry–manufacturing–control guidance prior to phase 1/2 clinical trials. 相似文献
10.
Pornpimon Adams Jaranit Kaewkungwal Chanthima Limphattharacharoen Sukanya Prakobtham Krisana Pengsaa Srisin Khusmith 《PloS one》2014,9(11)
Tensions between researchers and ethics committees have been reported in several institutions. Some reports suggest researchers lack confidence in the quality of institutional review board (IRB) reviews, and that emphasis on strict procedural compliance and ethical issues raised by the IRB might unintentionally lead to delays in correspondence between researchers and ethics committees, and/or even encourage prevarication/equivocation, if researchers perceive committee concerns and criticisms unjust. This study systematically analyzed the efficiency of different IRB functions, and the relationship between efficiency and perceived quality of the decision-making process. The major purposes of this study were thus (1) to use the IRB Metrics developed by the Faculty of Tropical Medicine, Mahidol University, Thailand (FTM-EC) to assess the operational efficiency and perceived effectiveness of its ethics committees, and (2) to determine ethical issues that may cause the duration of approval process to be above the target limit of 60 days. Based on a literature review of definitions and methods used and proposed for use, in assessing aspects of IRB quality, an “IRB Metrics” was developed to assess IRB processes using a structure-process-outcome measurement model. To observe trends in the indicators evaluated, data related to all protocols submitted to the two panels of the FTM-EC (clinical and non-clinical), between January 2010–September 2013, were extracted and analyzed. Quantitative information based on IRB Metrics structure-process-outcome illuminates different areas for internal-process improvement. Ethical issues raised with researchers by the IRB, which were associated with the duration of the approval process in protocol review, could be considered root causes of tensions between the parties. The assessment of IRB structure-process-outcome thus provides a valuable opportunity to strengthen relationships and reduce conflicts between IRBs and researchers, with positive outcomes for all parties involved in the conduct of human-subject research. 相似文献