Factors Affecting Plasma Viremia and Host Immune Responses in Dengue Infection

Dengue is the most important arboviral disease affecting humans. Although mortality is generally low, dengue generates a significant burden for health services in endemic countries. Pathogenesis is poorly understood. Secondary dengue is one important risk factor for severe disease, but current algorithms to differentiate primary from secondary infections are of limited utility. Viral burden is also thought to be a major factor influencing disease severity, but existing knowledge of the magnitude and kinetics of plasma viremia in association with different dengue serotypes, primary versus secondary immune status, and/or clinical markers of disease severity, is limited and inconsistent. I first set out to establish novel algorithms that permit differentiation of primary from secondary dengue at any day of illness with high accuracy. Using serial samples from 249 well-characterized patients, categorized as having primary or secondary infections on the basis of PRNTs after six months, I developed a number of models; the algorithm based on the Panbio Indirect IgG performed best (accuracy, 85%), although the models based on the in-house IgG and in-house IgM/IgG ratio were also good (accuracy, 84%). I subsequently applied the IgM/IgG ratio algorithm to define the immune status of 884 patients previously enrolled into early dengue studies. Using serial daily plasma samples I describe detailed plasma viremia responses for 581 DENV1, 152 DENV2 and 151 DENV3 infections. In general DENV1 infections resulted in higher plasma viremia than did DENV2 or DENV3 infections. Overall viremia was higher in primary than secondary DENV1 and DENV3 infections, although similar in DENV2 primary and secondary infections. In addition, higher viremia on Day3 of illness was significantly associated with several disease severity markers: lower platelet nadir, higher haemoconcentration and an increased risk of developing shock and bleeding. Finally I evaluated the effect of early prednisolone therapy on plasma viremia and immune responses, using serial samples from a clinical trial assessing the safety of early oral corticosteroid therapy. Prednisolone did not augment plasma viremia or NS1 antigenaemia, confirming the safety of using the drug during active viral replication. However, the effects of the drug on a range of immune correlates was also limited, consistent with prednisolone having negligible measurable benefits in the clinical trial on which this work was based

Differentiation Effect of Two Alkaloid Fractions from Vietnamese Lycopodiaceae on Mouse Neural Stem Cells

Various Lycopodium alkaloids have been studied for their various biological activities including anti-inflammatory, antioxidant, immunomodulatory, and neuroprotective activities. Moreover, these alkaloid compounds have high potential in the treatment of neuron degenerative disease. This study has been carried out to test the effect of Huperzia serrata (Thunb.) Trevis, and Lycopodium clavatum L alkaloid fractions on the mouse neural stem cells (NSCs). Firstly, the alkaloid fractions were used to verify its toxicity on NSCs. The multiple concentrations of alkaloid fractions from H. serrata (0.044; 0.088; 0.175; 0.35; 0.7; 1.4 mg/ml) and L. clavatum (0.031; 0.063; 0.125; 0.25; 0.50; 1.0; 2.0 mg/ml) have been used for the treatment of NSCs at period of 48h incubation. Results of the study suggested that the IC50 value of H. serrata and L. clavatum was 0.56 mg/ml and 0.50 mg/ml, respectively. Then, the NSCs were differentiated in the presence of 5 and 10 µg/ml of alkaloid fraction from H. serrata; 0.625 and 1.25 µg/ml of alkaloid fraction from L. clavatum for 6 days. Here, we observed the primary NSCs treated with alkaloid fraction extract from H. serrata showed the increased gene expression level of early neuron TUBB3 and neuron-specific cytoskeleton MAP2. On the other hand, the L. clavatum alkaloid fraction increased the expression of neural stem cell marker genes (Nestin and PAX6) and decreased neuron marker genes. In conclusion, these results established that alkaloid fraction from H. serrata promoted differentiation of the mouse NSCs to neuron cells, and L. clavatum extract had a capacity for stemness maintenance

Enantioselective separation of ofloxacin by ligand exchange chromatography

A ligand exchange HPLC method for enantioseparation of ofloxacin enantiomers was developed by a using C8 stationary phase. Chromatographic separation was performed on a Zorbax-300SB-C8 column eluted with the mobile phase consisting of 15 % methanol in water containing 10mM phenylalanin and 5 mM CuSO4 at flow rate of 0.8 mL/min. The method was simple, rapid and suitable for routine analytical studies of ofloxacin enantiomers

Factors affecting learner’s satisfaction towards online learning during COVID-19 pandemic: A case study of Vietnam

Online learning is being considered a new model of knowledge exchange in modern education. In parallel with the incredible impacts of the global pandemic, this is considered an opportunity to promote the development of online learning globally. Therefore, this study proposed a research framework including four factors affecting learner satisfaction towards online learning during the COVID-19 pandemic at a university, which are system quality, service quality, transformational leadership, and self-efficacy. A questionnaire was conducted online to assess which 131 respondents were representative students from two large private universities in Da Nang: FPT University and Duy Tan University. The results from the regression analysis show that three factors have a positive impact on learner satisfaction during COVID-19. This study concludes that students at private universities in Da Nang prioritize system quality as the most significant factor in their satisfaction with the online learning system, followed by transformational leadership and the last one is self-efficacy. Therefore, it can be more strategic for private organizations, developers, software designers, or even transformation-trained trainers to be emphasized to build a system of processes for implementing online learning for students effectively

ĐIỀU TRA TÌNH HÌNH CỎ LỒNG VỰC PHÁT SINH TRỞ LẠI TRÊN RUỘNG LÚA GIEO SẠ SAU KHI SỬ DỤNG THUỐC TRỪ CỎ Ở THỪA THIÊN HUẾ

Studying herbicide resistance in Vietnam is limited, and there are very few reports on the regrowth of weed after applying herbicides. A survey to investigate the cultivating habit and the barnyard grass regrowing in the direct-seeded rice fields after applying herbicides in Thua Thien Hue shows that the main labourers of rice cultivation are male with a low educational level to understand scientific and technical knowledge. The most common grass regrowing in direct-seeded rice fields after applying herbicides includes Barnyard grass (Echinochloa crus-galli), Grass-like fimbry (Fimbristylis miliacea), Bermuda grass (Cynodon dactylon), and Sprangletop (Leptochloa chinensis). The yield decreases from 12.1 to 14.0% because of regrowing of barnyard grass. The herbicides commonly used in Thua Thien Hue are Sofic 300EC (Pretilachlor) and Sunrice 15WDG (Ethoxysulfuron), but their effectiveness has decreased in recent time owing to farmers’ inappropriate spraying skills and the decrease in the effectiveness of herbicides. A more thorough assessment of the factors that cause grass regrowing after spraying herbicides is required for better weed management.Nghiên cứu sự kháng thuốc trừ cỏ ở Việt Nam còn hạn chế và có rất ít báo cáo về sự phát sinh của cỏ dại sau khi sử dụng thuốc trừ cỏ. Kết quả điều tra về tập quán canh tác và tình hình cỏ lồng vực phát sinh trở lại trên ruộng lúa sau khi sử dụng thuốc trừ cỏ ở Thừa Thiên Huế cho thấy lực lượng lao động chính canh tác lúa là nam giới, trình độ dân trí không cao nên khả năng tiếp thu kiến thức khoa học – kỹ thuật hạn chế. Các loại cỏ gây hại phổ biến trên ruộng lúa gieo sạ là cỏ lồng vực (Echinochloa crus-galli), cỏ chác (Fimbristylis miliacea), cỏ chỉ (Cynodon dactylon), cỏ đuôi phụng (Leptochloa chinensis) là các loại cỏ xuất hiện trở lại sau khi đã sử dụng thuốc trừ cỏ. Cỏ lồng vực mọc trở lại có thể gây giảm năng suất cây lúa 12,1–14,0%. Các loại thuốc trừ cỏ được sử dụng phổ biến là Sofic 300EC (Pretilachlor) và Sunrice 15WDG (Ethoxysulfuron). Hiệu quả thuốc trừ cỏ lúa có xu hướng giảm trong thời gian gần đây do kỹ thuật sử dụng và sự giảm hiệu quả của các sản phẩm thuốc trừ cỏ. Chúng tôi kiến nghị cần đánh giá đầy đủ hơn về các yếu tố gây nên tình trạng cỏ dại mọc trở lại sau khi phun thuốc để có định hướng quản lý cỏ dại tốt hơn

Modelling tools to analyze and assess the ecological impact of hydropower dams

We critically analyzed a set of ecological models that are used to assess the impact of hydropower dams on water quality and habitat suitability for biological communities. After a literature search, we developed an integrated conceptual model that illustrates the linkages between the main input variables, model approaches, the output variables and biotic-abiotic interactions in the ecosystems related to hydropower dams. We found that variations in water flow and water depth coupled with increased nutrient availability are major variables that contribute to structural and functional ecosystem changes. We also found that ecological models are an important tool to assess the impact of hydropower dams. For instance, model simulation of different scenarios (e.g., with and without the dam, different operation methods) can analyze and predict the related ecosystem shifts. However, one of the remaining shortcomings of these models is the limited capacity to separate dam-related impacts from other anthropogenic influences (e.g., agriculture, urbanization). Moreover, collecting sufficient high-quality data to increase the statistical power remains a challenge. The severely altered conditions (e.g., generation of very deep lakes) also lead to difficulties for standardized data collection. We see future opportunities in the integration of models to improve the understanding of the different processes affected by hydropower dam development and operation, as well as the use of remote sensing methods for data collection

A community participatory intervention model to reduce the health risks from biogas wastewater in Hanam Province, Vietnam

In Vietnam, using biogas to treat livestock waste is common, in particular on small holder farms. However, most small holder farms do not know how to use biogas correctly and wastewater can affect health and the environment. Using a participatory approach with farmers and other stakeholders we developed and implemented a set of interventions in Hanam province to reduce health risks from biogas wastewater. Twenty-four pig farmers were selected as a "core group" to be instrumental in developing the interventions and training other farmers to correctly use biogas. The intervention model was piloted for 6 months. Several outputs were obtained including i) approval and enforcement of a "huong uoc - village law" on environmental protection; ii) training of 24 farmers from the core group in communication skills to share information on using biogas; iii) development of a 6-step program of pig cage cleaning to limit waste loaded to biogas to improve the efficiency of biogas production; iv) a health monitoring books for humans and animals for use by families in the community. The results provided evidence that applying the participatory approach can lead to improved knowledge and practices of farmer using biogas and can reduce the health risks from biogas wastewater