Home sweet home? A case study of household dust contamination in Hong Kong

It is well recognized that many heavy metals have chronic effects on humans and as such, they are potential environmental health hazards, particularly to young children (see, for example, Body P, Inglis G, Dolan P, Mulcahy D. Environmental lead: a review. Crit Rev Environ Control 1991;20:299-310). Considerable attention has been paid to the study of metal pollution in city air, roadside dusts and soils. However, there is a lack of concern of the presence of trace metals in house dust in the populous city of Hong Kong, where it has traditionally been assumed that such pollutants are rapidly dispersed by ocean breezes. This research aims at quantifying the concentrations of heavy metals within the home environment in Hong Kong and their relationships with environmental factors. The results of this study seem to suggest that traffic and the age of the building and neighborhood are more important factors than the types of industry and socioeconomic status in affecting household dust contamination. The metal burdens in Kwung Tong, an old area with heavy traffic, are significantly higher than other districts. When a Kruskal-Wallis one-way analysis of variance was performed on the ranked metal concentrations in different housing districts, the Chi-square values are all significant at a probability level of < 0.001. This might be attributable to the fact that there is no highly contaminating industries (such as metal smelters, battery plants and petrochemicals) in Hong Kong. The dust metals may travel from the roads, through the windows and balconies, into the houses, as those homes that do not have their windows opened often had a lower level of contaminants in their house dust (median Cd= 3.6 microg/g; median Cu = 313.2 microg/g; median Pb = 144.6 microg/g; median Mn = 211.6 microg/g; and median Zn = 1,333.7 microg/g). Moreover, those occupants who sweep their floors or dust their furniture on daily bases, or use vacuum cleaners, had a lower level of metals inside their houses. Another finding of interest is that the color of the wall paint used in the house may be another factor influencing the contamination levels.     

Complex target SELEX

Aptamers are non-naturally occurring structured oligonucleotides that may bind to small molecules, peptides, and proteins. Typically, aptamers are generated by an in vitro selection process referred to as SELEX (systematic evolution of ligands by exponential enrichment). Aptamers that bind with high affinity and specificity to proteins that reside on the cell surface have potential utility as therapeutic antagonists, agonists, and diagnostic agents. When the target protein requires the presence of the cell membrane (e.g., G-protein-coupled receptors, ion channels) or a co-receptor to fold properly, it is difficult or impossible to program the SELEX experiment with purified, soluble protein target. Recent advances in which the useful range of SELEX has been extended from comparatively simple purified forms of soluble proteins to complex mixtures of proteins in membrane preparations or in situ on the surfaces of living cells offer the potential to discover aptamers against previously intractable targets. Additionally, in cases in which a cell-type specific diagnostic is sought, the most desirable target on the cell surface may not be known. Successful application of aptamer selection techniques to complex protein mixtures can be performed even in the absence of detailed target knowledge and characterization. This Account presents a review of recent work in which membrane preparations or whole cells have been utilized to generate aptamers to cell surface targets. SELEX experiments utilizing a range of target "scaffolds" are described, including cell fragments, parasites and bacteria, viruses, and a variety of human cell types including adult mesenchymal stem cells and tumor lines. Complex target SELEX can enable isolation of potent and selective aptamers directed against a variety of cell-surface proteins, including receptors and markers of cellular differentiation, as well as determinants of disease in pathogenic organisms, and as such should have wide therapeutic and diagnostic utility.     

In vivo and in vitro response to electrochemically anodized Ti-6Al-4V alloy

Tissues’ reactions to metals depend on a variety of properties of the metal, most notably surface structure. Anodizing has been shown to alter the surface properties of metal, thus eliciting a change in the biocompatibility of the metal. In order to evaluate the biocompatibility of unoxidized titanium alloy (Ti-6Al-4V) and anodized titanium alloy samples, the samples were implanted in murine abdominal subcutaneous tissues, and maintained for 2 and 4 weeks. The reaction of the abdominal subcutaneous connective tissues to the samples was then assessed. Fibrous connective tissue capsules were observed around the vicinity of the sample, and these capsules were shown to harbor fibroblasts, fibrocytes, and other cells, including neutrophils, macrophages, and giant multinucleated cells. The average thickness of the fibrous capsules observed around the anodized alloy samples was less than that of the capsules seen around samples of the unoxidized titanium alloy. Blood was obtained from the tails of the experimental mice, and blood cell analyses were conducted in order to assess the levels of leukocytes, red blood cells, and thrombocytes. The blood analysis results of the unoxidized control group and treatment group were all within normal ranges. In addition, the biocompatibility of the titanium alloy samples was evaluated using cell culture techniques. The numbers of MG-63 cells cultured on oxidized samples tended to be greater than those in the controls; however, these increases were not statistically significant. The alkaline phosphatase activity of the sample oxidized at 310 V evidenced significantly higher activity than was observed in the control group. These results indicate that the anodized Ti-6Al-4V alloy will be of considerable utility in biomedical applications.     

双显 就是这么神奇

液晶显示器越来越便宜，于是很多人将新购买液晶显示器和原来的CRT显示器组成双显示模式，更有人同时购买了同一型号的两台显示器，在使用双显示器中有些小技巧你发现了吗（以下以主显示器为“显示器1”，副显示器为“显示器2”）？