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This study reports the construction and validation of a CAFLUX (Chemically Activated Fluorescent Expression) HepG2 reporter cell line engineered to express a histone H2B–green fluorescent protein (H2B–GFP) fusion protein under the control of a dioxin-responsive cytochrome P450 1A1 (CYP1A1) promoter. A lentiviral construct containing a synthetic promoter with multiple dioxin-responsive elements (DREs) upstream of the H2B–EGFP coding sequence was cloned into the pFUGW vector, packaged in human embryonic kidney (HEK) 293FT cells, and used to transduce HepG2 hepatocellular carcinoma cells. Stable clones obtained by limiting dilution were screened for GFP expression in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The resulting CAFLUX HepG2 cells exhibited dose-dependent nuclear GFP fluorescence when exposed to aryl hydrocarbon receptor (AhR) agonists, with limits of detection of approximately 0.01 pM for TCDD and 0.1 pM for benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon (PAH). This reporter activity correlated with endogenous CYP1A1 mRNA expression as determined by quantitative polymerase chain reaction (qPCR), confirming that GFP signals reflected native transcriptional responses. In functional assays, curcumin suppressed GFP expression in a concentration-dependent manner and induced apoptotic morphology at higher doses, while extracellular vesicles (EVs) derived from adipose-derived stem cells (ADSCs) significantly reduced both GFP fluorescence and CYP1A1 mRNA levels, suggesting an inhibitory effect on AhR-driven transcription. The CAFLUX HepG2 reporter system therefore provides a sensitive and reproducible platform for real-time, nuclear-localized monitoring of AhR-mediated gene expression. Its responsiveness to both agonists and antagonists underscores its potential utility in toxicological evaluation, drug discovery, and the investigation of EV-mediated signaling in liver cancer models.

Antibiotic residues and antimicrobial resistance in surface water are issues of global concern, especially in developing countries. In this study, the occurrence of seven antibiotics and one antiparasitic agent was determined in surface water samples collected from four rivers running through Hanoi urban area in the Red River Delta, northern Vietnam. The pharmaceuticals in water samples were analyzed by solid-phase extraction combined with liquid chromatography–tandem mass spectrometry method. The concentrations of pharmaceuticals in our samples ranged from 3050 to 16,700 (median 7800) ng/L, which were generally higher than levels found in river water from many other locations in the world. Amoxicillin, oxfendazole, and lincomycin were the most dominant and frequently detected compounds (detection rate 100%), which together accounted for 76 ± 14% of total concentrations. Sulfacetamide and sulfamethoxazole were detected at moderate concentrations in more than two-thirds of the analyzed samples. The remaining antibiotics (i.e., azithromycin, ciprofloxacin, and ofloxacin) were found at lower detection frequency and concentrations. Antibiotic concentrations in the water samples were not significantly different between the investigated rivers. Meanwhile, levels of pharmaceuticals in the samples collected in February 2020 were higher than those found in the remaining samples, largely due to the sharp decrease in sulfamethoxazole and azithromycin concentrations of the samples collected in March and April. Considerable ecological risks of antibiotics in surface water were estimated for some compounds such as amoxicillin, ciprofloxacin, and ofloxacin.

Unsubstituted and methylated polycyclic aromatic hydrocarbons (22 PAHs and 17 Me-PAHs) were examined in surface sediments collected from the Red River and four inner-city rivers of Hanoi City, Vietnam. Concentrations of total PAHs and Me-PAHs ranged from 52 to 920 (median 710) and from 70 to 2600 (median 1000) ng/g dry weight in samples of dry and wet seasons, respectively. Significant correlation was observed between total PAHs and organic carbon contents (Spearman's ρ = 0.782; p < 0.05). PAHs were more abundant than Me-PAHs in all samples and dominated by 4–6 ring compounds. The most predominant PAHs were benzo[ghi]perylene, benzo[b/j]fluoranthene, chrysene, pyrene, fluoranthene, and phenanthrene. Methylated derivatives of naphthalene, phenanthrene, anthracene, and benz[a]anthracene were frequently detected. The patterns of PAHs indicated principal pyrogenic sources (notably gasoline exhaust) in this highly urbanized area. The occurrence of several PAHs were occasionally associated with adverse effects on benthic organisms of the inner-city rivers.

Abstract The introgression of antiviral strains of Wolbachia into Aedes aegypti mosquito populations is a public health intervention for the control of dengue. Plausibly, dengue virus (DENV) could evolve to bypass the antiviral effects of Wolbachia and undermine this approach. Here, we established a serial-passage system to investigate the evolution of DENV in Ae. aegypti mosquitoes infected with the wMel strain of Wolbachia. Using this system, we report on virus genetic outcomes after twenty passages of serotype 1 of DENV (DENV-1). An amino acid substitution, E203K, in the DENV-1 envelope protein was more frequently detected in the consensus sequence of virus populations passaged in wMel-infected Ae. aegypti than wild-type counterparts. Positive selection at residue 203 was reproducible; it occurred in passaged virus populations from independent DENV-1-infected patients and also in a second, independent experimental system. In wild-type mosquitoes and human cells, the 203K variant was rapidly replaced by the progenitor sequence. These findings provide proof of concept that wMel-associated selection of virus populations can occur in experimental conditions. Field-based studies are needed to explore whether wMel imparts selective pressure on DENV evolution in locations where wMel is established.

Background. Early prediction of severe dengue could significantly assist patient triage and case management. Methods. We prospectively investigated 7563 children with ≤3 days of fever recruited in the outpatient departments of 6 hospitals in southern Vietnam between 2010 and 2013. The primary endpoint of interest was severe dengue (2009 World Health Organization Guidelines), and predefined risk variables were collected at the time of enrollment to enable prognostic model development. Results. The analysis population comprised 7544 patients, of whom 2060 (27.3%) had laboratory-confirmed dengue; nested among these were 117 (1.5%) severe cases. In the multivariate logistic model, a history of vomiting, lower platelet count, elevated aspartate aminotransferase (AST) level, positivity in the nonstructural protein 1 (NS1) rapid test, and viremia magnitude were all independently associated with severe dengue. The final prognostic model (Early Severe Dengue Identifier [ESDI]) included history of vomiting, platelet count, AST level. and NS1 rapid test status. Conclusions. The ESDI had acceptable performance features (area under the curve = 0.95, sensitivity 87% (95% confidence interval [CI], 80%–92%), specificity 88% (95% CI, 87%–89%), positive predictive value 10% (95% CI, 9%–12%), and negative predictive value of 99% (95% CI, 98%–100%) in the population of all 7563 enrolled children. A score chart, for routine clinical use, was derived from the prognostic model and could improve triage and management of children presenting with fever in dengue-endemic areas.

Background Dengue virus serotypes (DENV-1 to -4) can be transmitted vertically in Aedes aegpti mosquitoes. Whether infection with the w Mel strain of the endosymbiont Wolbachia can reduce the incidence of vertical transmission of DENV from infected females to their offspring is not well understood. Methods A laboratory colony of Vietnamese Ae. aegypti , both with and without w Mel infection, were infected with DENV-1 by intrathoracic injection (IT) to estimate the rate of vertical transmission (VT) of the virus. VT in the DENV-infected mosquitoes was calculated via the infection rate estimation from mosquito pool data using maximum likelihood estimation (MLE). Results In 6047 F1 Vietnamese wild-type Ae. aegypti , the MLE of DENV-1 infection was 1.49 per 1000 mosquitoes (95% confidence interval [CI] 0.73–2.74). In 5500  w Mel-infected Ae. aegypti , the MLE infection rate was 0 (95% CI 0–0.69). The VT rates between mosquito lines showed a statistically significant difference. Conclusions The results reinforce the view that VT is a rare event in wild-type mosquitoes and that infection with w Mel is effective in reducing VT. Graphical Abstract

Furan derivatives are recognized for their diverse biological activities, particularly their antimicrobial properties. In this study, three new furan derivatives were isolated from acid-treated Chrysanthemum indicum flowers. The structures were elucidated using spectroscopic techniques and identified as methyl (E)-3-((5-(methoxymethyl)furan-2-yl)methylene)-4-oxopentanoate (1), methyl (Z)-3-((5-(methoxymethyl)furan-2-yl)methylene)-4-oxopentanoate (2), and methyl (E)-3-(furan-2-ylmethylene)-4-oxopentanoate (3). These compounds were evaluated for antibacterial activity against Vibrio spp. and Microcystis aeruginosa. Compound 3 showed the highest inhibition (63.5%) against M. aeruginosa at 50 μg/mL, with compounds 1 and 2 demonstrating lower activities (36.1% and 58.3%, respectively). The structural difference between compounds 1 and 2, limited to the double bond geometry, likely contributes to their varying efficacies. These findings indicate that furan derivatives from C. indicum could be promising candidates for antimicrobial applications, particularly in aquaculture.

Background Dengue viruses (DENV) can be transmitted from an adult female Aedes aegypti mosquito through the germ line to the progeny; however, there is uncertainty if this occurs at a frequency that is epidemiologically significant. We measured vertical transmission of DENV from field-reared Ae. aegypti to their F1 progeny after feeding upon blood from dengue patients. We also examined the transmission potential of F1 females. Methods We examined the frequency of vertical transmission in field-reared mosquitoes, who fed upon blood from acutely viremic dengue patients, and the capacity for vertically infected females to subsequently transmit virus horizontally, in two sets of experiments: (i) compared vertical transmission frequency of field-reared Ae. aegypti and Ae. albopictus , in individual progeny; and (ii) in pooled progeny derived from field- and laboratory-reared Ae. aegypti. Results Of 41 DENV-infected and isofemaled females who laid eggs, only a single female (2.43%) transmitted virus to one of the F1 progeny, but this F1 female did not have detectable virus in the saliva when 14 days-old. We complemented this initial study by testing for vertical transmission in another 460 field-reared females and > 900 laboratory-reared counterparts but failed to provide any further evidence of vertical virus transmission. Conclusions In summary, these results using field-reared mosquitoes and viremic blood from dengue cases suggest that vertical transmission is uncommon. Field-based studies that build on these observations are needed to better define the contribution of vertical DENV transmission to dengue epidemiology.

The presence of antibiotics in the environment is of significant concern due to their adverse effects on aquatic ecosystems. This study provides an assessment of potential ecological risks (RQ) associated with the concentrations of eight antibiotics and antiparasitics (amoxicillin—AMO, azithromycin—AZI, ciprofloxacine—CIP, ofloxacine—OFL, oxfendazole—OXF, lincomycin—LIN, sulfacetamide—SCE and sulfamethoxazole—SME) in the surface water of 13 urban lakes in Hanoi city, Vietnam during the period 2021–2023. The findings revealed considerable variations in the total concentrations of these 8 substances (T AB ), ranging from below the method detection limit (< MDL) to 2240 ng L −1 with an average of 330.4 ng L −1 . Among the 8 antibiotics and antiparasitics examined, OXF, AMO, and SCE were undetectable, while the others were present at a range of concentrations (in ng L −1 ): OFL: 129 (< MDL-1530); CIP: 87.1 (< MDL-608); LIN: 72.7 (< MDL-676); SME: 41.5 (< MDL-504); AZI: 0.03 (< MDL-1). The calculated RQ values for these antibiotics in the Hanoi lakes indicated a high ecological risk for OFL and CIP to bacteria, a medium to high risk for SME for phytoplankton, a high risk for LIN to phytoplankton, while the risk for invertebrates was deemed negligible for all antibiotics across all lakes. The strong, positive correlation between T AB concentrations and different microbial and environmental variables ( Escherichia coli , ammonium, phosphate, and chemical oxygen demand) suggests that untreated domestic wastewater is the primary pollution source in these Hanoi lakes. These results should be used to raise public awareness and to encourage the implementation of strategies targeted at managing antibiotic use. They also underscore the need to reduce inputs of untreated, antibiotic-containing wastewater into urban lakes, such as those in Hanoi and advocate for the establishment of national limits for antibiotic concentrations in surface water.

The Red River (Vietnam) is representative of a south-east Asian river system, strongly affected by climate and human activities. This study aims to quantify the spatial and seasonal variability of CO2 partial pressure and CO2 emissions of the lower Red River system. Water quality monitoring and riverine pCO2 measurements were carried out for 24 h at five stations distributed along the lower Red River system during the dry and the wet seasons. The riverine pCO2 was supersaturated relative to the atmospheric equilibrium (400 ppm), averaging about 1589±43 ppm and resulting in a water–air CO2 flux of 530.3±16.9 mmol m−2 d−1 for the lower Red River. pCO2 and CO2 outgassing rates were characterized by significant spatial variation along this system, with the highest values measured at Hoa Binh station, located downstream of the Hoa Binh Dam, on the Da River. Seasonal pCO2 and CO2 outgassing rate variations were also observed, with higher values measured during the wet season at almost all sites. The higher river discharges, enhanced external inputs of organic matter from watersheds and direct inputs of CO2 from soils or wetland were responsible for higher pCO2 and CO2 outgassing rates. The difference in pCO2 between the daytime and the night-time was not significant, suggesting weak photosynthesis processes in the water column of the Red River due to its high sediment load.