Expression of tyrosine hydroxylase and growth-associated protein 43 in aging atrial fibrillation patients of Xinjiang Uygur and Han nationality.

The aim of this study was to explore the changes in gene and protein expressions of tyrosine hydroxylase (TH) and growth-associated protein 43 (GAP43) in aging atrial fibrillation patients of Xinjiang Uygur and Han nationality, and the significance of the changes. Real-time polymerase chain reaction and Western blot analysis were used to detect gene and protein expressions of TH and GAP43 in atrial tissues of 54 patients with valvular heart disease. mRNA and protein expressions of GAP43 and TH were significantly different between the sinus rhythm and atrial fibrillation groups (P < 0.05). Protein expressions of GAP43 and TH of both nationalities differed significantly between the sinus rhythm group and the atrial fibrillation group (P < 0.05), whereas there was no statistical difference between the two nationalities within each group (P > 0.05). Protein expressions of GAP43 and TH differed significantly among different age groups of different nationalities in the sinus rhythm and atrial fibrillation groups (P < 0.05); only protein expression of GAP43 differed significantly in different age groups in the atrial fibrillation group (P < 0.05). The changes of mRNA and protein expressions of TH and GAP43 played a vital role in the process of maintaining the atrial fibrillation. Therefore, increased expression of TH and GAP43 might be a molecular mechanism for left atrial myoelectricity remodeling of aging atrial fibrillation patients, which might be potential therapeutic targets of atrial fibrillation.

The effectiveness of composite lining systems in controlling the leakage of leachate from sanitary landfills to groundwater.

Leachate, the hazardous liquid that percolated through the refuse layers of a sanitary landfill, if it leaks through the landfill lining system, can become a serious source of groundwater pollution. In the past, leaks have been detected in many landfills lined with flexible membrane liners (FML) whose failure may be attributed to flaws such as imperfect seaming, rips, and tears of the membrane, or from chemical attack that dissolves the membrane. Recent studies have shown that composite lining systems which include either a clayey subbase or a layer of geotextile in addition to the FML, can substantially reduce the leakage of leachate. Therefore in this study, four different lining systems are proposed and evaluated to determine their effectiveness in controlling leachate flow under various degree of flaws (referred to as leakage fraction LF) in the FML. The Hydrologic Evaluation of Landfill Performance (HELP) computer model of the Environmental Protection Agency of USA, currently the most widely accepted model for predicting the performance of leachate collection systems in that country, is used to evaluate the following lining systems: (1) a single FML or liner, (2) a single FML with a clayey composite, (3) a single FML with a geotextile called Claymax, and (4) a double FML. Based on the climatic conditions and the present lining construction cost of Alaska, the study shows that a single FML or liner is the most economical but it is also the least effective in controlling leachate flow. Design (3), a single FML with a geotextile, costs about 50 percent more but it reduces the leakage of leachate by several orders. Design (2) is also effective but the cost incurred in constructing a 3 feet thick clayey subbase is prohibitive and thus to effectively and economically minimize the hazards of potential groundwater contamination by leachate, Design (3) is recommended as the composite lining system for future landfill sites.