Vertical differentiation of soil organic carbon in mature natural forests in China.

We analyzed the effects of meteorological factors and soil properties on vertical variation of SOC, based on soil organic carbon (SOC) density in different soil layers (0-10, 10-20, 20-30, 30-50, and 50-100 cm) from 131 mature natural forests in different climate zones in China. The results showed that SOC density decreased with increasing soil depth (0-30 cm) in temperate coniferous, temperate deciduous broadleaved, subtropical deciduous broadleaved and subtropical evergreen broadleaved forests. There were significant regional variations of SOC density in 0-100 cm soil layer. SOC density of 0-100 cm soil layer in temperate coniferous forests was higher than temperate deciduous broadleaved forests, and was higher in subtropical evergreen broadleaved forests than subtropical deciduous broadleaved forests. SOC density was significantly positively correlated with soil clay content, mean annual precipitation, and aboveground net primary production, and significantly negatively correlated with soil pH and mean annual temperature. Mean annual precipitation and mean annual temperature influenced input and output of SOC, while soil pH and clay content affected SOC accumulation. Therefore, protecting mature natural coniferous and evergreen broadleaved forests would benefit forest carbon sequestration in China.

[Netrin-1 protein expression in gastric cancer and its correlation with clinicopathologic features and prognosis].

OBJECTIVE: To evaluate the relationship between netrin-1 protein, clinicopathologic features and prognosis in gastric cancer patients. METHODS: Tissue micro-array and immunohistochemistry were used to detect expression of netrin-1 protein and Ki67. And clinicopathological relevance of netrin-1 protein and Ki67 in gastric cancer were analyzed. Survival rates was evaluated by Kaplan-Meier survival curves. Cox regression analysis was performed to evaluate the possibility of netrin-1 expression as an independent prognostic factor for gastric cancer. RESULTS: The positive-expression rate of netrin-1 protein, paracancerous netrin-1 protein and Ki67 in tumor tissue from 67 patients with gastric cancer were 49%, 42% and 60%, respectively. netrin-1 protein expression might be related to depth of invasion, lymth node metastasis and distant metastasis (P<0.05). But no correlation was observed in sex, tumor diameter and tumor grade (P>0.05). There was correlation between different degrees of netrin-1 expression and distant metastases (P<0.05). No correlation was found in the expression of Ki67 and clinicopathological features. The correlation between the expression of netrin-1 and Ki67 was observed (r=0.359, P<0.05). Using Kaplan-Meier survival curves and the log-rank test, the correlation of netrin-1 expression, different degrees of netrin-1 expression and survival (P<0.05) were also observed. But netrin-1 expression was not significantly correlated with the prognosis of gastric cancer (RR = 1.335, 95% CI: 0.612-2.914). CONCLUSION: netrin-1 protein may be related with tumorigenesis and tumor progression by affecting proliferation. The detection for netrin-1 may be helpful to evaluate the clinicopathological parameters and survival time. However, it is not an independent prognostic factor for gastric cancer.

[Analysis of clinical risk factors in progression from acute lung injury to acute respiratory distress syndrome in severe trauma patients].

OBJECTIVES: To investigate the potential risk factors of affecting progression from acute lung injury (ALI) to acute respiratory distress syndrome in severe trauma population. METHODS: Twenty potential risk factors of affecting progression of acute lung injury were examined by univariate and multivariate logistic analyses among the severe trauma patients in a retrospective study. RESULTS: All of 375 specially severe trauma patients with ALI were included for analysis. The six risk factors that affected the progression from acute lung injury to acute respiratory distress syndrome were sepsis, duration of trauma, APACHE II score, DIC, aspiration of gastric contents, and advanced age. Specific risk factors also affected different patient subpopulations at different degrees. CONCLUSION: Impact of sepsis, DIC and duration of trauma that predict progression of ALI exists throughout the entire treatment period while aspiration of gastric contents and APACHE II score might affect aggravation of ALI only during the early period; due to deterioration of pulmonary function and severely traumatic injury, advanced age is still an independent risk factor; patients with these risk factors need aggressive supportive cares as early as possible in order to prevent further aggravations.