Estradiol and Hyperhomocysteinemia Are Linked Predominantly Through Part Renal Function Indicators.

Background: Previous studies have shown that estrogen, kidney function, and homocysteine (Hcy) or hyperhomocysteinemia (HHcy) are related to each other. However, the underlying biological mechanisms still remain unclear. We aimed to explore the association between estradiol (E2) and HHcy in the female population, and to further evaluate the mediating role of renal function indicators. Methods: This unmatched case-control study consisted of 1,044 female participants who were 60.60 ± 12.46 years old. Data on general demographic characteristics, such as age, smoking and drinking status, menopause and so on were collected in a personal interview, and laboratory examinations were performed by well-trained personnel. The mediating effect model was applied to analyze the direct and indirect effects of E2 on Hcy. Results: The average levels of Hcy and E2 of the participants were 12.6 µmol/L and 14.95 pg/ml. There were statistical differences in renal indexes blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA), glomerular filtration rate (GFR) and E2 between HHcy group and non-HHcy group. The logistic regression models showed that UA was risk factor for HHcy (P <0.001), GFR and E2 were protective factors for HHcy after adjusting for confounding factors (P <0.001). The indirect effects of E2 on Hcy through UA and GFR accounted for 14.63 and 18.29% of the total impacts of E2 on Hcy. Conclusions: These data indicated that E2 was a protective factor of HHcy, and the effects of E2 on HHcy may be mediated by renal function indicators UA and GFR.

[Assessment on the ecological suitability in Zhuhai City, Guangdong, China, based on minimum cumulative resistance model].

Urban landscape has the characteristics of spatial heterogeneity. Because the expansion process of urban constructive or ecological land has different resistance values, the land unit stimulates and promotes the expansion of ecological land with different intensity. To compare the effect of promoting and hindering functions in the same land unit, we firstly compared the minimum cumulative resistance value of promoting and hindering functions, and then looked for the balance of two landscape processes under the same standard. According to the ecology principle of minimum limit factor, taking the minimum cumulative resistance analysis method under two expansion processes as the evaluation method of urban land ecological suitability, this research took Zhuhai City as the study area to estimate urban ecological suitability by relative evaluation method with remote sensing image, field survey, and statistics data. With the support of ArcGIS, five types of indicators on landscape types, ecological value, soil erosion sensitivity, sensitivity of geological disasters, and ecological function were selected as input parameters in the minimum cumulative resistance model to compute urban ecological suitability. The results showed that the ecological suitability of the whole Zhuhai City was divided into five levels: constructive expansion prohibited zone (10.1%), constructive expansion restricted zone (32.9%), key construction zone (36.3%), priority development zone (2.3%), and basic cropland (18.4%). Ecological suitability of the central area of Zhuhai City was divided into four levels: constructive expansion prohibited zone (11.6%), constructive expansion restricted zone (25.6%), key construction zone (52.4%), priority development zone (10.4%). Finally, we put forward the sustainable development framework of Zhuhai City according to the research conclusion. On one hand, the government should strictly control the development of the urban center area. On the other hand, the secondary urban center area such as Junchang and Doumen need improve the public infrastructure to relieve the imbalance between eastern and western development in Zhuhai City.

[Extracting municipal solid waste dumps based on high resolution images].

The dramatically increasing informal MSW dumps are endangering the urban environment. Remote sensing (RS) technologies are more efficient to monitor and manage municipal solid wastes (MSW) than traditional survey-based methods. In high spatial resolution remotely sensed images, these irregularly distributed dumps have complex compositions and strong heterogeneities, thus it is still hard to extract them automatically no matter the pixel-or object-based image analysis method is used. Therefore, based on the analysis of MSW characteristics, the present study develops a multiresolution strategy to extract MSW dumps by combining image features at both high resolution and resampled low heterogeneity images, while the high resolution images can provide detailed information and the low resolution images can suppress the strong heterogeneities of informal MSW dumps. Taking the QuickBird image covering part of Beijing as an example, this multi-resolution strategy produced a high accuracy (75%), indicating that this multi-resolution strategy is quite effective for extracting the open-air informal MSW dumps.

[Spatiotemporal differentiation of land cover change and grassland degradation pattern in Yangtze River headwaters area].

Based on field survey data, remote sensing images and statistical data, this paper analyzed the spatiotemporal differentiation of land use and grassland degradation patterns in Yangtze River headwaters area in 1987-2007, and discussed the main natural factors (elevation, position and slope) leading to the changes of this area's grassland ecological environment. In 1987-2007, the fragmentation of this area' s landscape patterns had an increasing trend, and natural environment and climate change were the main driving forces of land use pattern change. There existed significant differences in the areas of grassland degradation at different altitudes. Grassland degradation mainly occurred at altitudes 4800-5100 m. The grassland degradation area tended to increase with increasing elevation, and the proportions of the degradation area varied greatly over different slopes and aspects. The climate in the study area became warm and dry, and the spatial structure of regional land cover changed obviously. The distribution patterns of grassland degradation at different elevation, position and slope coincided with alpine environment and human disturbances, suggesting that alpine environment and climatic change were the decisive factors to the grassland ecosystem pattern in Yangtze River headwaters area.