Doxorubicin Loaded Magnesium Oxide Nanoflakes as pH Dependent Carriers for Simultaneous Treatment of Cancer and Hypomagnesemia.

Doxorubicin (DOX) is an anticancer drug commonly used in treating cancer; however, it has severe cytotoxicity effects. To overcome both the adverse effects of the drug and mineral deficiency (i.e., hypomagnesemia) experienced by cancer patients, we have developed magnesium oxide (MgO) nanoflakes as drug carriers and loaded them with DOX for use as a targeted drug delivery (TDD) system for potential application in cancer therapy. The synthesis employed herein affords pure, highly porous MgO nanoparticles that are void of the potentially harmful metal contaminants often discussed in the literature. Purposed for dual therapy, the nanoparticles exhibit an impressive 90% drug loading capacity with pH dependent drug releasing rates of 10% at pH 7.2, 50.5% at pH 5.0, and 90.2% at pH 3. Results indicate that therapy is achievable via slow diffusion where MgO nanoflakes degrade (i.e., dissolve) under acidic conditions releasing the drug and magnesium ions to the cancerous region. The TDD system therefore minimizes cytotoxicity to healthy cells while supplying magnesium ions to overcome hypomagnesemia.

Microorganisms and heavy metals associated with atmospheric deposition in a congested urban environment of a developing country: Sri Lanka.

The presence of bacteria and heavy metals in atmospheric deposition were investigated in Kandy, Sri Lanka, which is a typical city in the developing world with significant traffic congestion. Atmospheric deposition samples were analyzed for Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb which are heavy metals common to urban environments. Al and Fe were found in high concentrations due to the presence of natural sources, but may also be re-suspended by vehicular traffic. Relatively high concentrations of toxic metals such as Cr and Pb in dissolved form were also found. High Zn loads can be attributed to vehicular emissions and the wide use of Zn coated roofing materials. The metal loads in wet deposition showed higher concentrations compared to dry deposition. The metal concentrations among the different sampling sites significantly differ from each other depending on the traffic conditions. Industrial activities are not significant in Kandy City. Consequently, the traffic exerts high influence on heavy metal loadings. As part of the bacterial investigations, nine species of culturable bacteria, namely; Sphingomonas sp., Pseudomonas aeruginosa, Pseudomonas monteilii, Klebsiella pneumonia, Ochrobactrum intermedium, Leclercia adecarboxylata, Exiguobacterium sp., Bacillus pumilus and Kocuria kristinae, which are opportunistic pathogens, were identified. This is the first time Pseudomonas monteilii and Ochrobactrum intermedium has been reported from a country in Asia. The culturable fraction constituted ~0.01 to 10%. Pigmented bacteria and endospore forming bacteria were copious in the atmospheric depositions due to their capability to withstand harsh environmental conditions. The presence of pathogenic bacteria and heavy metals creates potential human and ecosystem health risk.

PM(10)-bound polycyclic aromatic hydrocarbons: biological indicators, lung cancer risk of realistic receptors and 'source-exposure-effect relationship' under different source scenarios.

Cancer has become a critical health issue in the world heritage city Kandy, Sri Lanka. Polycyclic aromatic hydrocarbons (PAHs), one of persistent organic pollutants, in the atmosphere may be a major etiological factor in lung carcinogenicity. Over the very high concentrations of ambient air PAHs reported in Kandy, this paper is focused on setting priorities to control human exposure to PAHs in prevention of cancer. On re-appraisal of the classical indicator benzo(a)pyrene (B[a]P) for atmospheric PAHs-related carcinogenicity, B[a]P failed to reflect the toxicity completely and may not be the sole indicator for risk assessment studies in complex multi-sourced urban environments. The excess lifetime lung cancer risks of atmospheric PAHs with 'less than lifetime exposure' were assessed based on both 'B[a]P toxic equivalents' and 'B[a]P surrogate epidemiological' approach of risk quantification, over emissions characterized urban, suburban, and rural areas of Kandy. In urban heavy traffic areas, PAH-related additional cancer burden has been 942 million(-1) over 30 y of exposure. Over the whole study area, ∑p-PAHs show strong correlation (r=0.8) to the predicted risk levels. While the urban and suburban predicted cancer risk levels could not show significant correlation to their emission sources indicating the real complexity in mega urban environments, the rural lung cancer risk levels correlated perfectly with the source, firewood combustion. Policy decisions on environment and health could be based on established correlations among 'emission sources-exposures-health effects'. The priority for "analysis of options and policy formulation to reduce inhalation PAHs exposure of population in Kandy" was considered "moderate to high".