Silica Nanoparticles Decorated with Ceria Quantum Dots Modulate Intra- and Extracellular Reactive Oxygen Species Formation and Selectively Reduce Human A375 Melanoma Cell Proliferation.

Nanomaterials show great promise for cancer treatment. Nonetheless, most nanomaterials lack selectivity for cancer cells, damaging healthy ones. Cerium dioxide (ceria, CeO2) nanoparticles have been shown to exert selective toxicity toward cancer cells due to the redox modulating properties they display as their size decreases. However, these particles suffer from poor suspension stability. The efficacy of CeO2 nanoparticles for cancer treatment is hampered by their innate high surface energy, which leads to particle agglomeration and, consequently, reactivity loss. This effect increases as particle size decreases; as such, quantum dots (QDs) suffer most from this phenomenon. In this study, it is proposed that silicon dioxide (silica, SiO2) nanoparticles can provide an inert platform for surface encrusted CeO2 QDs and that the resulting nanocomposite (hereafter QDCeO2/SiO2) not only will exhibit negligible agglomeration compared with CeO2 alone but also will improve the modulation of reactive oxygen species (ROS) leading to selective reduction of human A375 melanoma cell proliferation. The SiO2 nanoparticles had a bimodal size distribution with median particle size of 66 and 168 nm, while the CeO2 quantum dots encrusted on their surface had a size of 3.2 nm. An elevated Ce3+/Ce4+ ratio led to the QDCeO2/SiO2 nanocomposite displaying synergistic superoxide dismutase- and catalase-like activity, favoring the accumulation of ROS at pH 6.5 which translated into QDCeO2/SiO2 exerting selective oxidative stress in, and toward, the melanoma cells. Treatment with 50 µg mL-1 QDCeO2/SiO2 significantly reduced cell proliferation by 27% compared to untreated control cells in the colony formation assay. Treatment with either SiO2 or CeO2 alone did not affect the cell proliferation. These results highlight the benefit of dispersing CeO2 QDs on the surface of core nanoparticles and the resulting enhancement of selective redox reactivity and proliferation arrest when compared to CeO2 nanoparticles alone. Furthermore, the method employed here to encrust CeO2 QDs could lead to the facile synthesis of new nanocomposites with enhanced control of ROS activity, not only for in vitro studies using other cancer cell lines of interest but also in animal models and perhaps leading to clinical trials in melanoma patients.

Letter to Editor: Antiviral activities of ginseng and its potential benefit against monkeypox virus: A mini review.

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Designing Comprehensive Public Health Surveillance for Enteric Fever in Endemic Countries: Importance of Including Different Healthcare Facilities.

Background: Designing comprehensive surveillance to generate credible burden estimates of enteric fever in an endemic country can be challenging because care-seeking behavior is complex and surveillance in different healthcare facilities may lead to documentation of different epidemiological characteristics. Methods: We conducted retrospective surveillance in 3 healthcare facilities to identify culture-confirmed enteric fever cases in Dhaka, Bangladesh, from January 2012 through December 2016. The study settings included (1) hospital in-patient department (IPD), (2) hospital out-patient department (OPD), and (3) private consultation center OPD. We analyzed the cases to understand their distribution, age ranges, and antibiotic susceptibility patterns across the settings. Results: Of the 1837 culture-confirmed enteric fever cases, 59% (1079 of 1837) were OPD cases. Children with enteric fever hospitalized in the IPDs were younger than children seeking care at the hospital OPD (median age: 45 vs 60 months) or private OPD (median age: 45 vs 72 months). Multidrug resistance rates were slightly higher in hospital IPD cases than in private OPD cases (26% vs 24%). Conclusions: In each facility, we identified different epidemiological characteristics, and lack of consideration of any of these may result in misinterpretation of disease burden, identification of different age groups, and/or antibiotic susceptibility patterns.

Enteric Fever and Related Contextual Factors in Bangladesh.

Enteric fever remains a major public health problem in the developing world. With the emergence of antimicrobial resistance, disease prevention is becoming essential. There is evidence that improvement of contextual factors, such as socioeconomic development and water supply and sanitation, reduce the burden of this disease. However, such positive results are not universal. This study describes enteric fever trends in Bangladesh along with these factors' progress between 1990 and 2014. Retrospective enteric fever data were collected from Dhaka Shishu (children) Hospital (DSH), Shishu Shasthya Foundation Hospital (SSFH), International Center for Diarrheal Disease Research, Bangladesh, and Popular Diagnostic Center (PDC). Contextual factors data were gathered from relevant organizations and their websites and plotted against time to see trends. During 2001-2014, data for a total of 131,449 blood cultures were available at DSH, SSFH, and PDC. Of those, 7,100 (isolation rate 5.4%) yielded either Salmonella enterica serovar Typhi or Salmonella enterica serovar Paratyphi growth without visible change in isolation rate trends. Contextual factors data were reported from 1990 to 2014. There were significant developments for sanitation facilities, drinking water supply, female literacy, and reduction in poverty head count ratio. During this time period, population density also increased significantly. Despite improvements in these contextual factors in Bangladesh, the enteric fever trend seems steady, possibly because of high population density and unplanned development of water supply and sewerage system. Although proper development of these two factors is important, immunization with an effective vaccine is instrumental to prevent this disease immediately in endemic countries such as Bangladesh, specifically to overcome the challenge of emerging resistance to available antibiotics.