Effect of ethanol on the elasticities of double-stranded RNA and DNA revealed by magnetic tweezers and simulations.

The elasticities of double-stranded (ds) DNA and RNA, which are critical to their biological functions and applications in materials science, can be significantly modulated by solution conditions such as ions and temperature. However, there is still a lack of a comprehensive understanding of the role of solvents in the elasticities of dsRNA and dsDNA in a comparative way. In this work, we explored the effect of ethanol solvent on the elasticities of dsRNA and dsDNA by magnetic tweezers and all-atom molecular dynamics simulations. We found that the bending persistence lengths and contour lengths of dsRNA and dsDNA decrease monotonically with the increase in ethanol concentration. Furthermore, the addition of ethanol weakens the positive twist-stretch coupling of dsRNA, while promotes the negative twist-stretch coupling of dsDNA. Counter-intuitively, the lower dielectric environment of ethanol causes a significant re-distribution of counterions and enhanced ion neutralization, which overwhelms the enhanced repulsion along dsRNA/dsDNA, ultimately leading to the softening in bending for dsRNA and dsDNA. Moreover, for dsRNA, ethanol causes slight ion-clamping across the major groove, which weakens the major groove-mediated twist-stretch coupling, while for dsDNA, ethanol promotes the stretch-radius correlation due to enhanced ion binding and consequently enhances the helical radius-mediated twist-stretch coupling.

The Comparison of PCR Kits for the Detection of Erythrocytic Parasites on Filter Paper.

Dried blood spot (DBS) based PCR was considered an inexpensive and feasible method for detecting pathogens in the blood. The DBS carrier filter paper and PCR kits are crucial for accurate diagnosis. We evaluated 4 types of filter papers and 20 PCR kits for DBS samples. The PCR detecting Plasmodium results showed that the minimum detection limit of the 4 filter papers was 1 × 102 parasites/µL, and the positive rates of 20 PCR kits ranged from 0% to 100%. PCR results were satisfactory for detecting Plasmodium falciparum (P. falciparum) and Plasmodium. vivax (P. vivax) in archived DBS samples and Babesia gibsoni (B. gibsoni) in fresh pet DBS samples. Our results provided a useful reference for the detection of blood pathogens with DBS samples and direct PCR, especially for screening the cost-efficacy combination of filter paper and PCR kit in resource-limited areas.

Nischarin-siRNA delivered by polyethylenimine-alginate nanoparticles accelerates motor function recovery after spinal cord injury.

A previous study by our group found that inhibition of nischarin promotes neurite outgrowth and neuronal regeneration in Neuro-2a cells and primary cortical neurons. In recent years, more and more studies have shown that nanomaterials have good prospects in treatment of spinal cord injury. We proposed that small interfering RNA targeting nischarin (Nis-siRNA) delivered by polyethyleneimine-alginate (PEI-ALG) nanoparticles promoted motor function recovery in rats with spinal cord injury. Direct microinjection of 5 µL PEI-ALG/Nis-siRNA into the spinal cord lesion area of spinal cord injury rats was performed. From day 7 after surgery, Basso, Beattie and Bresnahan score was significantly higher in rats from the PEI-ALG/Nis-siRNA group compared with the spinal cord injury group and PEI-ALG/Control-siRNA group. On day 21 after injection, hematoxylin-eosin staining showed that the necrotic area was reduced in the PEI-ALG/Nis-siRNA group. Immunohistochemistry and western blot assay results confirmed successful inhibition of nischarin expression and increased protein expression of growth-associated protein-43 in the PEI-ALG/Nis-siRNA group. These findings suggest that a complex of PEI-ALG nanoparticles and Nis-siRNA effectively suppresses nischarin expression, induces expression of growth-associated protein-43, and accelerates motor function recovery after spinal cord injury.

Endometriosis and regional lymph node involvement in a rat model.

OBJECTIVE(S): To establish an experimental bowel endometriosis model in the rat and to investigate regional lymph node involvement. STUDY DESIGN: Twenty Sprague-Dawley rats were subjected to autologous transplantation of endometrial tissue to the ileocecum by laparotomy. After two months, endometriotic lesions and mesenteric lymph nodes were harvested by repeat laparotomy subjected to histologic assessment regarding the histologically verified presence of endometriosis in the ileocecum and in mesenteric lymph nodes. RESULT(S): A total of 20 rats were subjected to autologous transplantation of endometrial tissue to the ileocecum. Ileocecal endometriosis was successfully induced in 19/20 (95%) rats. In 18/20 animals, the mesenteric lymph node was identified and resected. Regional lymph node involvement by endometriosis was identified in 0/18 mesenteric lymph nodes. CONCLUSION(S): Endometriosis can be successfully induced in a rat model by autologous transplantation of endometrial tissue. In this experimental rodent endometriosis model, regional mesenteric lymph node involvement by endometriosis was not identified.