[Characteristics of nitrogen cycling in farm systems in a small watershed of Three Gorges Reservoir Area, China].

In China, the agricultural activities are often carried out by single family, and the balance of nitrogen in every farm may have great effect on agricultural production and environment. A farm survey was carried out on the amounts of chemical fertilizers consumed, the amounts of food and feed purchased, and the livestock manures used in Zhangjiachong watershed of Three Gorges Reservoir Area for each farmer. According to the characteristics of nitrogen flow, farms in this watershed could be divided into 5 types: breeding specialized farms, orange-growing farms, tea-growing farms, vegetable-growing farms and traditional farms. Differences in environmental nitrogen load were observed among the five farm types in the following order: breeding specialized farms > vegetable-growing farms > orange-growing farms > tea-growing farms approximately = traditional farms, being (363 +/- 129), (355 +/- 127), (345 +/- 107), (152 +/- 60) and (151 +/- 73) kg x (hm2 x a)(-1) respectively by nitrogen. Nitrogen cycle for different farm fields showed that field surplus nitrogen ranged from (102 +/- 68) to (303 +/- 134) kg x (hm2 x a)(-1) among different farms. Among the five farm types, the field surplus nitrogen followed the order of vegetable-growing farms > citrus-growing farms > tea-growing farms > breeding specialized farms approximately = traditional farms, being (303 +/- 134), (262 +/- 100), (111 +/- 46), (102 +/- 68) and (103 +/- 67) kg x (hm2 x a)(-1). The nitrogen from farm life activities accounted for 28% of the total N load, while the field surplus nitrogen was 72%. It was estimated that field nitrogen consumption was the predominated nitrogen pollution source in the watershed. However, the farmer's daily life pollution should not to be neglected. Breeding specialized farms, vegetable-growing farms and orange-growing farms were the high potential pollution sources for the water environment in the watershed, and the major attention should be paid to these types of farms. Field survey on farm nitrogen cycle is of significance in evaluating the nitrogen flows in the agro-ecosystems and revealing the characteristics of nitrogen cycling in the region.

[Cyclic imine toxin gymnodimine: a review].

Gymnodimine (GYM), an algal toxin first detected from New Zealand oysters in 1994, is identified as a cyclic imine toxin and produced by Karenia selliformis, with imino nitrogen attached on loop-coil. Imine is the poisonous functional group of the toxin. GYM has a low oral toxicity, but its acute lethal toxicity of intra-peritoneal injection for mice is very high. Up to now, few reports have been published on the detailed information about the toxicity mechanism of GYM. Based on limited literatures, this paper reviewed the GYM's structure, producer, toxicity mechanism, carrying animals, geological distribution, degradation metabolism, dose-effect relation, and risk evaluation, and proposed the further research directions on algal toxin.

Potential role of adipocytokine leptin in acute coronary syndrome.

By activating immune cells or a direct action on the vascular wall, leptin may affect the initiation and progression of atherosclerosis. We investigated whether plasma leptin concentration is associated with coronary artery disease, with particular focus on the relationship between plasma leptin and the development of an acute coronary syndrome. Plasma leptin, interleukin-6 and high-sensitivity C-reactive protein were measured in 34 patients with acute coronary syndrome and 21 with stable angina. Their results were compared with those of 21 normal controls. Plasma leptin levels were significantly higher in the acute coronary syndrome group (13.36 +/- 5.02 ng.mL(-1)) compared to the stable angina group (8.97 +/- 4.06 ng.mL(-1)) or normal controls (5.14 +/- 2.75 ng.mL(-1)). Interleukin-6 and high-sensitivity C-reactive protein were also higher in the acute coronary syndrome group, and leptin correlated positively with interleukin-6 and high-sensitivity C-reactive protein. These findings suggest that plasma leptin levels may be a useful marker of systemic inflammation, and measurement of plasma leptin may be helpful in assessing the risk of developing coronary heart disease.