[Changes in Soil Nitrogen Components and Their Relationship with Environmental Factors with Different Tea Plantation Ages].

Changes in soil nitrogen components in tea gardens affect the soil nitrogen supply capacity and nitrogen cycle. In this study, soil samples were collected from forest land, cultivated land, and tea gardens with different plantation ages (30, 50, and 70 years) to explore the changes in soil nitrogen components and their relationship with physicochemical properties and enzyme activities. The results showed that:① with the increase in tea plantation age, the silt, total phosphorus, and urease and catalase activities gradually increased, whereas the sand, clay, pH, electrical conductivity, soil organic carbon, and the activities of invertase gradually decreased. The alkaline phosphatase activity increased first and then decreased with the increase in tea plantation age, and no significant differences were observed in soil water content and acid phosphatase activity. ② With the increase in tea plantation age, the contents of acid ammonia nitrogen, amino acid nitrogen, and nitrate nitrogen (NO3--N) increased significantly, and the contents of total nitrogen, acid ammonia nitrogen, hydrolyzable unknown nitrogen, and non-hydrolyzable nitrogen in tea gardens were significantly higher than those in forest land. ③ The total phosphorus, alkaline phosphatase, and urease were the main factors affecting soil nitrogen components. Among them, organic nitrogen components were significantly correlated with total phosphorus and alkaline phosphatase, and inorganic nitrogen components were significantly correlated with alkaline phosphatase, whereas total nitrogen had significant correlations with sand, silt, total phosphorus, urease, and alkaline phosphatase.

[Effect of Spartina alterniflora Invasion on Soil C:N:P Stoichiometry in Coastal Wetland of Hangzhou Bay].

The invasion of Spartina alterniflora poses a great threat to coastal wetland ecosystems. In this study, the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus under a Spartina alterniflora invasion were explored using ANOVA in a coastal wetland in Hangzhou Bay, and the driving coupling relationship between soil environmental factors and soil C:N:P stoichiometric characteristics of the coastal wetland were further explored based on the redundancy analysis (RDA), boosted regression tree (BRT), and partial least squares-structural equation (PLS-SEM) model. The results showed that:① after the invasion of Spartina alterniflora, soil N:P and total nitrogen (TN) in the wetland increased significantly, and with the increase in invasion time, TN and N:P decreased significantly, whereas soil organic carbon (SOC), C:N, and C:P increased significantly. ② The RDA model revealed that the main factors affecting the stoichiometric characteristics of topsoil C:N:P were SOC>electrical conductivity (EC)>TN in winter and SOC>bulk density (BD)>TN in summer. ③ The BRT model showed that under the invasion of Spartina alterniflora, TN was the key factor affecting soil C:N and N:P, and SOC was the key factor affecting C:P. ④ The PLS-SEM model showed that clay and water content directly affected SOC, thus affecting C:N and C:P; the clay and EC directly affected total phosphorus (TP), thus affecting N:P and C:P; and the EC directly affected TN, thus affecting C:N and N:P. In conclusion, the invasion of Spartina alterniflora had a significant impact on soil C:N:P stoichiometric characteristics in the study area. Soil physical properties and nutrient content directly or indirectly affected soil C:N:P stoichiometric characteristics to varying degrees.

Tortoise Plastron and Deer Antler Gelatin Prevents Against Neuronal Mitochondrial Dysfunction In Vitro: Implication for a Potential Therapy of Alzheimer's Disease.

Mitochondrial dysfunction with oxidative damage plays the fundamental roles in the pathogenesis of Alzheimer's disease. In traditional Chinese medicine (TCM) practice, animal tissue-derived gelatins are often used as nootropic agents to treat cognitive deterioration and senile dementia. Tortoise plastron gelatin (TPG) and deer antler gelatin (DAG) are the two most commonly used gelatins for this purpose. This study sought to examine the effects of the two gelatins in preventing neuronal mitochondria from oxidative damage. PC12 cells, a cell line derived from rat pheochromocytoma, exposed to the neurotoxin Aß25-35 served as an in vitro model of Alzheimer's disease. The cells were separately pre-treated with TPG and DAG at various concentrations ranging from 6.26 µg/ml-200 µg/ml, followed by co-incubation with 20 µM Aß25-35 for different duration. Cell viability, mitochondrial membrane potential (MMP) and ultrastructure, intracellular ATP, reactive oxygen species (ROS) and calcium (Ca2+) level, the expression of mitochondrial dynamic proteins and biomarkers of apoptosis were measured. Pretreatment with TPG and DAG reversed the Aß-induced reduction of cell viability in a dose-dependent manner. Both TPG and DAG significantly increased MMP and ATP, alleviated the accumulation of damaged mitochondrial fragments, and normalized the aberrant expression of multiple mitochondrial dynamic proteins of the Aß-exposed cells. Both gelatins also suppressed intracellular ROS overproduction and Ca2+ overload, overexpression of cytochrome c and pro-apoptosis biomarkers induced by the Aß exposure. These results suggest that TPG and DAG may have the anti-dementia potential by preventing neuronal mitochondria from oxidative damage.

[Application of dynamic substrate mapping in ablation of ventricular tachycardias in arrhythmogenic right ventricular cardiomyopathy].

OBJECTIVE: To study the application of abnormal electrophysiological substrate mapping for guiding ablation of ventricular tachycardias in arrhythmogenic right ventricular cardiomyopathy (ARVC-VTs) using a non-contact mapping system. METHODS: Dynamic substrate mapping was performed in three male ARVC patients during sinus rhythm. The sites of the earliest activation, exit point and activation sequence were mapped for each induced VT. RESULTS: Three different patterns of substrates were determined in 3 patients, which located in right ventricular outflow tract, anterior right ventricular wall, and anterolateral right ventricular wall, respectively. Five different clinical VTs [mean CL (348 +/- 65) ms] were induced. Of 5 VTs, three were originated from substrate or boundary of substrate, and two had a remote origin. One VT conducted through the substrate. Linear ablations were created between the sites of the earliest ventricular activation and the VT exit point, or across the critical isthmus. The five clinical VTs were successfully ablated. There were no VT recurrences during 20 months of follow-up. CONCLUSIONS: Defining the abnormal electrophysiologic VT substrates is useful for understanding the mechanisms of ARVC-VTs and determining an ablation strategy. Linear ablation across a critical isthmus or between the earliest activation and the exit point can effectively cure these arrhythmias.