Usage of nanoparticles with their potential toxicity assessment and regulatory guidelines

In recent times engineered nanoparticles have been receiving much attention from researchers due to their extensive use in a variety of chemical, biological, and industrial areas. Their physiochemical properties have led to a number of uses in commercial products. Considering their broad applications, with increasing human contact the risks of exposure are also increasing. In vivo toxicity experiments involving administering nanoparticles to living organisms have shown their adverse effects on organ development and reproduction. Nanoparticles can be considerably more toxic than the large-sized particles since they can move relatively freely compared to bulkier molecules. Henceforth, it is our duty to assess the harmful health consequences associated with human exposure to nanoparticles in order to improve safe production and use. We will review the current applications of nanoparticles, and issues related to their toxicity. We will focus on safety regulations, risk assessment and regulatory guidelines of nanoparticles. The validation and standardization of nanotoxicity tests will further promote safe applications of nanotechnology in our daily lives.     

Late-presenting complete heart block after pediatric cardiac surgery

Late presenting complete heart block after pediatric cardiac surgery is a rare complication and its management is well defined once the initial diagnosis in made timely and appropriately. In this report we described a child who underwent atrioventricular septal defect repair with a normal sinus rhythm during the postoperative period, as well as during the first 2 years of follow up.She subsequently developed complete heart block with bradycardia that required insertion of a pacemaker. Here we discuss this unusual late-presenting complication, possible risk factors, and management.     

Chemometric Evaluation of Near Infrared,Fourier Transform Infrared,and Raman Spectroscopic Models for the Prediction of Nimodipine Polymorphs

The objective of this study was to assess the performance of the chemometric model to predict the proportion of the recrystallized polymorphs of nimodipine from the cosolvent formulations. Ranging from 100% to 0% (w/w) of polymorph I, the two polymorphs mixtures were prepared and characterized spectroscopically using Fourier transformed infrared spectroscopy (FTIR), near-infrared spectroscopy (NIR), and Raman spectroscopy. Instrumental responses were treated to construct multivariate calibration model using principal component regression (PCR) and partial least square regression approaches. Treated data showed better model fitting than without treatment, which demonstrated higher correlation coefficient (R²) and lower root mean square of standard error (RMSE) and standard error (SE). Multiple scattering correction and standard normal variate exhibited higher R² and lower RMSE and SE values than second derivative. Goodness of fit for FTIR and NIR (R² ~ 0.99) data was better than Raman (R² ~ 0.95). Furthermore, the models were applied on the recrystallized polymorphs obtained by storing nimodipine-cosolvent formulations at selected stability conditions. The relative composition of the polymorphs differed with storage conditions. NIR-chemical imaging on recrystallized sample of nimodipine at 15°C qualitatively corroborated the model-based prediction of the two polymorphs. Therefore, these studies strongly suggest the importance of the potential utility of the chemometric model in predicting nimodipine polymorphs.     

变黑白头翁提取物降低亚砷酸盐对小鼠精细胞的毒性

目的：研究变黑白头翁提取物降低亚砷酸盐对小鼠精细胞毒性的作用。方法：给予实验小鼠亚砷酸钠（20mg／kg每日），并分别在第30、60、90天对小鼠进行检测。亚砷酸盐中毒小鼠被分为2组，其中一组给予变黑白头翁提取物（35mg／kg），另一组给予85％乙醇。通过检测小鼠精细胞凋亡标志蛋白CYP1A1、p53及caspase3的活性，确定细胞及DNA的损伤情况，并测定睾丸毒性标志物的水平。通过圆二色光谱仪及熔化温度数据检测变黑白头翁提取物与DNA的相互作用情况。结果：亚砷酸盐中毒小鼠的所有细胞凋亡标志蛋白及睾丸毒性标志物的水平均有所上升，而经变黑白头翁提取物治疗的小鼠上述各项指标均降低或恢复至正常水平。变黑白头翁提取物与DNA相互作用，引起了DNA结构和构象的变化。结论：变黑白头翁提取物可作为砷中毒引起的生殖功能损害的治疗药物给予研究和开发。     

Antibody-Secreting Cell Responses after Vibrio cholerae O1 Infection and Oral Cholera Vaccination in Adults in Bangladesh

Infection with Vibrio cholerae and oral cholera vaccines (OCVs) induce transient circulating plasmablast responses that peak within approximately 7 days after infection or vaccination. We previously demonstrated that plasmablast responses strongly correlate with subsequent levels of V. cholerae-specific duodenal antibodies up to 6 months after V. cholerae infection. Hence, plasmablast responses provide an early window into the immunologic memory at the mucosal surface. In this study, we characterized plasmablast responses following V. cholerae infection using a flow cytometrically defined population and compared V. cholerae-specific responses in adult patients with V. cholerae O1 infection and vaccinees who received the OCV Dukoral (Crucell Vaccines Canada). Among flow cytometrically sorted populations of gut-homing plasmablasts, almost 50% of the cells recognized either cholera toxin B subunit (CtxB) or V. cholerae O1 lipopolysaccharide (LPS). Using a traditional enzyme-linked immunosorbent spot assay (ELISPOT), we found that infection with V. cholerae O1 and OCVs induce similar responses to the protein antigen CtxB, but responses to LPS were diminished after OCV compared to those after natural V. cholerae infection. A second dose of OCV on day 14 failed to boost circulating V. cholerae-specific plasmablast responses in Bangladeshi adults. Our results differ from those in studies from areas where cholera is not endemic, in which a second vaccination on day 14 significantly boosts plasmablast responses. Given these results, it is likely that the optimal boosting strategies for OCVs differ significantly between areas where V. cholerae infection is endemic and those where it is not.     

Antioxidative Potential of Duranta Repens (Linn.) Fruits Against H2O2 Induced Cell Death In Vitro

The effects of Duranta repens fruits were investigated on H₂O₂ induced oxidative cell death to evaluate its antioxidative potential in vitro. HEK293T cells were treated with different concentrations [0–1000 µg/ ml] of ethanol extract (E-Ex) and methanol extract (M-Ex) of D. repens for 24h, and then treated with 100 µM H₂O₂ for 24h. Cell viability, antioxidant parameters of cells, and antioxidant constituents of the extracts were determined. Treatment with limited dose of E-Ex or M-Ex increased the survival rate of H₂O₂-treated HEK293T cells, however the extra-high dose showed growth inhibitory effect. Treatment with E-Ex or M-Ex protected cellular lipid per-oxidation. In vitro analyses showed the 2,2-diphenyl-1-picrylhydrazyl and H₂O₂ scavenging activities as well as reducing potential of the extracts. We report here that the limited dose of E-Ex and M-Ex possess antioxidative potential, which can protect H₂O₂-induced oxidative cell damage.