Novel flavonoids from the stem of Popowia cauliflora

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.     

Fibronectin‐binding protein,FbpA, is the adhesin responsible for pathogenesis of Listeria monocytogenes infection

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.     

Enhanced anti-topoisomerase II activity by mucoadhesive 4-CBS–chitosan/poly (lactic acid) nanoparticles

In this study, the biodegradable mucoadhesive 4-carboxybenzensulfonamide chitosan (4-CBS–chitosan)/poly (lactic acid) (PLA) nanoparticles were fabricated by the electrospray ionization technique for enhancing anti-topoisomerase II (Topo II) activity. The obtained (4-CBS–chitosan/PLA)-DOX nanoparticles were characterized using SEM, particle size analyzer. We emphasis on encapsulation efficiency, in vitro drug release behavior and also performed in vitro studies of Topo II inhibitory activity using gel electrophoresis. In addition, the cytotoxicity of the 4-CBS–chitosan/PLA nanoparticles using MTT assay was also studied. The mean particle size of spherical shaped (4-CBS–chitosan/PLA)-DOX is less than 300 nm. The DOX loaded 4-CBS–chitosan/PLA composite nanoparticles produced high entrapment efficiency of 85.8% and provided the prolonged release of DOX extended to 26 days and also still had strong Topo II inhibitory activity up to 77.4%. Overall, it was shown that 4-CBS–chitosan/PLA nanoparticles could be promising carriers for controlled delivery of anticancer drugs.     

Purification,characterization, and gene sequencing of a catalase from an alkali- and halo-tolerant bacterium,Halomonas sp. SK1

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.     

Synthesis of rotenoid derivatives with cytotoxic and topoisomerase II inhibitory activities

6-Deoxyclitoriacetal (1) and a series of 11 further derivatives of it (2-12) were synthesized and evaluated for their cytotoxic and topoisomerase IIα inhibitory activities. Compounds bearing epoxide (2), morpholine (6) and benzylamine (10) moieties showed promising in vitro cytotoxic activities against four cancer cell lines, with IC₅₀ values ranging from 0.38 to 0.73 μM. These three compounds also strongly inhibited topoisomerase II activity at 68.3-93.5% and showed a moderately high DNA intercalating property.     

Synthesis and characterization of chitosan-homocysteine thiolactone as a mucoadhesive polymer

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.     

Dengue infection in children in Ratchaburi, Thailand: a cohort study. II. Clinical manifestations

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.     

New insulating particleboards prepared from mixture of solid wastes from tissue paper manufacturing and corn peel

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.     

Quantitative analysis and formulation development of a traditional Thai antihypertensive herbal recipe

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.     

Is Your Ethics Committee Efficient? Using “IRB Metrics” as a Self-Assessment Tool for Continuous Improvement at the Faculty of Tropical Medicine,Mahidol University,Thailand

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.