Correlation between pyrethroid knockdown resistance and mutation frequency of voltage-gated sodium channel and its application in Aedes aegypti management.

Aedes aegypti, the primary vector responsible for transmitting dengue fever in southern Taiwan, has developed a relatively high resistance to synthetic pyrethroids. It has evolved four amino acid substitutions in the voltage-gated sodium channel (VGSC), namely S996P, V1023G, F1565C, and D1794Y. To unveil the distribution and correlation of VGSC mutations and pyrethroid resistance among different field populations, Ae. aegypti collected from various districts in Kaohsiung and Tainan Cities underwent tests for resistance development against different pyrethroids and frequency of S996P, V1023G, F1565C, and D1794Y substitutions. The adult knockdown assay revealed a relatively high knockdown resistance in the Ae. aegypti populations from Kaohsiung and Tainan against permethrin, cypermethrin, and fenvalerate (averaging >50-fold). Conversely, less resistance was observed against α-cypermethrin, deltamethrin, λ-cyhalothrin, cyfluthrin, and etofenprox (averaging <35-fold). Using Polymerase Chain Reaction/restriction fragment length polymorphism analysis, four mutant haplotypes were identified in these field populations. Notably, the SIAVFD and SIBVFD wild haplotypes were absent. Analysis utilizing IBM SPSS Statistics 20.0 and Spearman's rank correlation coefficient indicated that Haplotype C (PIAGFD), especially P allele, frequency displayed a significant positive correlation with five Type II pyrethroid resistance, while 1023G and 1023G/G exhibited a significant association with permethrin and fevalerate resistance. Conversely, Haplotype E (SIBVCD) negatively correlated with pyrethroid resistance, particularly fenvalerate resistance (-0.776). Haplotype C and E were the most prevalent and widely distributed among the investigated field populations. This prevalence of haplotype C is likely tied to the extensive and excessive use of Type II pyrethroids for dengue control over the past three decades. Given the significant positive correlation, the best-fit lines and R2 values were established to facilitate the swift prediction of knockdown resistance levels to various pyrethroids based on VGSC mutation frequency. This predictive approach aims to guide insecticide usage and the management of pyrethroid resistance in the field populations of Ae. aegypti in Taiwan.

Direct immersion solid-phase microextraction combined with ambient ionization tandem mass spectrometry to rapidly distinguish pesticides in serum for emergency diagnostics.

Despite the fact that carbamates and organophosphates cause acute poisoning via different mechanisms and require disparate management, they are indistinguishable by current clinical assays. Herein, direct immersion solid-phase microextraction (DI-SPME) plus thermal desorption-electrospray ionization tandem mass spectrometry (TD-ESI/MS/MS) was developed to discern them. Both pesticides spiked in human serum were extracted by SPME and analyzed by TD-ESI/MS/MS. This is a promising emergency care platform as rapid analyses could be done in tiny sample volumes with satisfactory recovery (89.46%-116.32%), precision (covariance <20%), sensitivity (LOD <0.1 µg/mL), turnaround time (<5 minutes), and linearity (R2 = 0.9827-0.9992) within 0.1-100 µg/mL.

The molecular mechanism of the open-closed protein conformational cycle transitions and coupled substrate binding, activation and product release events in lysine 5,6-aminomutase.

How a protein domain motion is coupled to the catalytic cycle is a current subject in enzymology. We render down a complicated domain motion in the 5'-deoxyadenosylcobalamin and pyridoxal-5'-phosphate codependent radical enzyme, lysine 5,6-aminomutase, into dominant contributions from Lys370α and Asp298α to the critical Co-C bond cleavage trigger and open-closed cycle transitions.

Preparation and characterization of a biodegradable polyurethane hydrogel and the hybrid gel with soy protein for 3D cell-laden bioprinting.

3D printing shows great potential for fabricating customized scaffolds for tissue regeneration. Using hydrogel as a bioink for cell printing provides a biological platform for basic research and potential medical treatments. In this study, a waterborne poly(ε-caprolactone) (PCL)-based biodegradable polyurethane (PU) with a soft segment replaced with 20 mol% of poly(l-lactide) (PLLA) diol or poly (d,l-lactide) (PDLLA) diol was prepared. These two PUs formed compact packing structures at temperatures ≥37 °C. They responded differently to temperature changes and the presence of electrolytes because of the difference in the free volume. With their thermal-responsive properties, both PU dispersions could form a gel in 3 min with the gel modulus reaching about 6-8 kPa after 30 min. To enhance the structural integrity during layer-by-layer deposition, the hybrid hydrogel of PU and soy protein isolate (PU/SPI hybrid) was further developed. The PU/SPI hybrid dispersion could undergo rapid gelation at 37 °C with the modulus reaching 130 Pa in 1 min. Moreover, the PU/SPI hybrid gel was readily blended with cells and printed at 37 °C without preheating. Neural stem cells (NSCs) were embedded in the hydrogels and analyzed for cell viability, metabolism, proliferation, and gene expression of neural-related markers. Cells cultured in the PU/SPI hybrid construct had better survival and proliferation than those in the PU gel. The PU/SPI hybrid ink may provide unique rheological properties for direct cell/tissue printing at 37 °C and a biomimetic microenvironment for cell survival, growth, and differentiation.

3D bioprinting of neural stem cell-laden thermoresponsive biodegradable polyurethane hydrogel and potential in central nervous system repair.

The 3D bioprinting technology serves as a powerful tool for building tissue in the field of tissue engineering. Traditional 3D printing methods involve the use of heat, toxic organic solvents, or toxic photoinitiators for fabrication of synthetic scaffolds. In this study, two thermoresponsive water-based biodegradable polyurethane dispersions (PU1 and PU2) were synthesized which may form gel near 37 °C without any crosslinker. The stiffness of the hydrogel could be easily fine-tuned by the solid content of the dispersion. Neural stem cells (NSCs) were embedded into the polyurethane dispersions before gelation. The dispersions containing NSCs were subsequently printed and maintained at 37 °C. The NSCs in 25-30% PU2 hydrogels (∼680-2400 Pa) had excellent proliferation and differentiation but not in 25-30% PU1 hydrogels. Moreover, NSC-laden 25-30% PU2 hydrogels injected into the zebrafish embryo neural injury model could rescue the function of impaired nervous system. However, NSC-laden 25-30% PU1 hydrogels only showed a minor repair effect in the zebrafish model. In addition, the function of adult zebrafish with traumatic brain injury was rescued after implantation of the 3D-printed NSC-laden 25% PU2 constructs. Therefore, the newly developed 3D bioprinting technique involving NSCs embedded in the thermoresponsive biodegradable polyurethane ink offers new possibilities for future applications of 3D bioprinting in neural tissue engineering.

Zinc chloride for odontogenesis of dental pulp stem cells via metallothionein up-regulation.

INTRODUCTION: Previous studies have shown that zinc chloride (ZnCl(2)) can induce metallthionein (MT) in the liver and kidney to protect tissues against toxicants and shows a better corneal wound healing than conventional drugs do. We hypothesized that ZnCl(2) can promote odontogenesis of dental pulp stem cells (DPSCs) via MT. The purpose of this study was to investigate the effects of ZnCl(2) on human DPSCs and the expression of MT. METHODS: DPSCs were isolated by flow cytometry with selective surface marker CD146 and STRO-1. After they grew into confluence, DPSCs were induced into odontoblasts with or without ZnCl(2) supplemented in the culture medium for 21 days. The effect of ZnCl(2) on DPSCs differentiation was examined followed by alkaline phosphatase staining/activity and quantitative real-time polymerase chain reaction analysis. RESULTS: By treating DPSCs with ZnCl(2), the duration of mineralization was shortened and expressions of differentiation markers into odontoblasts were more significant than those without ZnCl(2) stimulation. Besides, the MT gene expression was increased with the increasing expressions of odontoblasts' markers after treated with ZnCl(2). CONCLUSION: This was the first report that ZnCl(2) could promote odontoblastic differentiation of DPSCs through the up-regulation of gene MT.

Relations of caregiving stress and health depend on the health indicators used and gender.

Extensive research has evaluated relations between stress and health. These studies have varied in the type of stress examined (acute vs. chronic) and in the way in which health has been operationalized. Here we examine relations between chronic stress and 25 indicators of various health dimensions (e.g., physiological indexes, medical records, and self-reports of global health; symptoms, functional status, health service utilization, and psychosocial distress/quality of life). We also assessed whether such relations are moderated by gender, an individual difference variable that is important to health and longevity. Samples included 157 community-residing older adults (M age = 69.4 years, 31.8% men), approximately half of whom were caregivers for a spouse with Alzheimer's disease, and half were demographically similar noncaregiver spouses. Principal component analyses on the 25 health measures resulted in 5 factors that met standard criteria for acceptance. In women, caregivers reported worse physical health and psychological health than noncaregivers, but their physiological risk was similar. In men, caregivers had greater physiological risk, but they reported better physical health than did men noncaregivers. Researchers who study chronic stress and health should consider the possibility that the relation between chronic stress and health may vary for men and women depending on the type of health being assessed.