猪胚胎死亡的影响因素及其预防措施

猪胚胎死亡直接影响着母猪的产仔数，并进而影响着养猪生产的经济效益。因此，在深入研究猪胚胎死亡规律及其影响因素的基础上，通过有效的措施降低胚胎死亡率，对提高母猪窝产仔数和经济效益具有十分重要的意义。本文综述了影响猪胚胎死亡的遗传、环境、营养和疾病等因素，并对生产实践中如何通过综合预防措施降低猪胚胎死亡率进行了初步探讨。     

陇东黄土高原冬小麦生产农业气象要素分析

对陇东黄土高原半湿润半干旱气候区旱地冬小麦生长期光、热、水三要素与产量进行了相关分析,得出对冬小麦产量起决定作用的农业气象要素为:孕穗—成熟期光照时数,≥0℃积温,开春土壤含水量 返青—孕穗期降水量(R2 3H)。建立了逐步回归方程,Y=-317.138 0.6317X1 0.4647X2。     

Upregulation of neurokinin A levels by nerve growth factor in the experimental asthmatic guinea pig

AIM: To explore the regulatory mechanism of nerve growth factor (NGF) on neurokinin A in the experimental asthmatic guinea pig. METHODS: Radioimmunoassay was used to determine the alteration of neurokinin A levels in the lower respiratory tract and visceral sensory afferent sites while NGF was absent (inhalation of NGF antibody through nasal cavity) in the asthmatic guinea pig. RESULTS: The contents of neurokinin A in the trachea, bronchus, lung, C₇-T₅ spinal ganglia and the correspondent spinal dorsal horn, nodose ganglia and solitary nucleus area in the experimental asthmatic guinea pig with the absent of NGF in the respiratory tract were much lower than those in the asthmatic and control groups (P＜0.01). CONCLUSION: NGF upregulated the contents of neurokinin A in the lower respiratory tract and visceral sensory sites of the experimental asthmatic guinea pig, and both might be involved in the pathogenesis of asthma.     

Relation between TNF-α,TNFR I expression and apoptosis in oral lichen planus

AIM: To examine the expression and distribution of tumor necrosis factor-α (TNF-α), tumor necrosis factor receptor I (TNFR I) and apoptosis in oral lichen planus, and evaluate their roles and relation in the oral lichen. METHODS: Immunohistochemical technique and TUNEL were employed to study the expression of TNF-α, TNFR I and apoptosis in 50 cases of oral lichen planus and 10 normal oral mucosa specimens. RESULTS: Compared with the normal control group, TNF-α expression was upregulated in mononuclear cells in lamina propria and decreased in keratinocytes in oral lichen planus lesion (P<0.05). On the contrary, TNFR I expression was increased in keratinocytes and decreased in lamina propria in oral lichen planus lesion (P<0.05). The increased apoptosis index in keratinocytes and the decreased apoptosis index in lamina propria were found in oral lichen planus (P<0.05). CONCLUSION: The accelerated apoptosis of keratinocytes and the inhibition of lymphocytes apoptosis may contribute to the formation and progression of oral lichen planus.     

Characteristics in the secretion of liver TNF-α induced by infusion of LPS into veins in goats

AIM: To study the role of liver in immune regulation in experimental endotoxemia. METHODS: 17 castrated male goats were subjected to simultaneously installing catheters in jugular, hepatic and portal veins by surgery. Four days later, lipopolysaccharide (LPS) was infused in term of three groups as followings: In group ①, LPS of 20 EU (endotoxin unit, EU)·kg^-1 was infused into portal vein; In group ②, LPS of 20 EU·kg^-1 was infused into jugular vein and LPS of 1 500 EU·kg^-1 infused into jugular vein in group ③. Before and after infusion, blood samples were collected from the three veins through the catheters for 8 h.The plasma levels of TNF-α were measured by RIA. RESULTS: In group ①, the plasma TNF-α levels of hepatic and portal vein rose to peak value at 5 h, but that of the jugular vein did not changed. In group ②, the plasma TNF-α levels in hepatic vein rose to peak value at 3 h. The TNF-α levels of jugular vein rose to peak value at 1 h and the one in portal vein enhanced continuously between 0-8 h. In group ③, the plasma TNF-α levels in jugular, hepatic and portal vein rose to significant peaks at 1 h simultaneously. CONCLUSION: During experimental endotoxemia,liver showed different dynamic characteristics in TNF-α secretion according to the pathway and doses of LPS delivery.     

Inhibition of K562 cell growth by antisense drug targeting with VEGF mRNA in vitro

AIM: To investigate inhibition of K562 cell growth by antisense drug targeted VEGF mRNA. METHODS: X7, 20-mer antisense sequences were selected, synthesized and modified with phosphorothioate. The drug was transfected into K562 cells in the present of lipofection. Cell growth was assayed by trypan blue dye exclusion assay and MTT. The level of VEGF protein in the media was determined by ELISA. The morphology of apoptotic cells were observed by Giemsa staining, and the propotion of apoptotic cells was detected by flow cytometry. RESULTS: The antisense drug inhibited growth of K562 and downregulated expression of VEGF protein significantly, compared with Scrambed control group and showed dose-dependent relation. Signs of apoptosis of K562 cells were not observed. CONCLUSION: Inhibition of K562 cell proliferation, but not cells apoptosis induction is the mechanism of inhibing growth of K562 cells by antisense drug targeted VEGF mRNA. At same time, VEGF has function of promoting K562 cell proliferation, and VEGF mRNA may be a new target attached by drugs.     

Nitric oxide-mediated the cardioprotection of tumor necrosis factor-alpha on cultured neonatal rat cardiomyocytes during hypoxia/reoxygenation

AIM: To investigate the role of nitric oxide synthase (NOS), soluble guanylyl cyclase (sGC) and protein kinase C (PKC) signaling in tumor necrosis factor-α (TNF-α)-induced cardioprotection against hypoxia/reoxygenation (H/R) injury. METHODS: Neonatal rat ventricular myocytes were pretreated with TNF-α or sodium nitroprusside (SNP) or L-arginine (L-Arg), respectively, for 12 h and then subjected to continuous hypoxia for 12 h, followed by reoxygenation for 6 h. The manganese superoxide dismutase (Mn-SOD) activity of the cells was measured after H/R. Myocyte injury was determined by the release of lactic dehydrogenase (LDH). RESULTS: TNF-α (10⁵ U/L) significantly increased the Mn-SOD activity and decreased release of LDH from ventricular myocytes. The cardioprotection against H/R injury was induced by the pretreatment with SNP (5 μmol/L) or L-Arg (5 mmol/L), which was blocked by ODQ (10 μmol/L), the specific sGC inhibitor, and Chel (5 μmol/L), the specific PKC inhibitor. Pretreatment with L-NAME (100 μmol/L), ODQ, Chel, antoxidant 2-MPG (400 μmol/L) or tyrosine kinase inhibitor genistein (50 μmol/L) attenuated the increased Mn-SOD activity and reduced LDH level induced by TNF-α. CONCLUSION: The results suggest that NO may play a role in TNF-α-induced cardioprotection, which is mediated by sGC and PKC.     

赤峰市松山区土地利用动态变化及其原因分析

以TM遥感资料为信息源 ,利用 3S技术手段 ,对内蒙古自治区赤峰市松山区 1987,1993,2 0 0 0年的土地利用变化进行了分析。结果表明 ,在不同年度内 ,其主要的土地利用类型为耕地、草地和林地。土地利用类型的总量变化也以这 3种土地利用类型和建设用地变化最大。而从年变化速率看 ,1987- 2 0 0 0年 ,以建设用地的增加和未利用土地类型的减少最为快速。从土地利用类型转化的方向看 ,以耕地、草地和林地相互之间的转化最为频繁。从土地利用类型的空间稳定性看 ,耕地的稳定性最高 ,其次为草地 ;而最不稳定的土地利用类型为未利用土地。利用相关分析所作的土地利用变化动因显示 ,该地区土地利用变化的驱动因素主要是社会与经济因素 ,其中以总人口、农业总产值、粮食作物产量总计、农牧民人均纯收入、化肥使用面积和化肥实物量等因子的作用最大 ,而自然因素对该地区土地利用变化的影响极小。     

内蒙古沙尘暴的成因、趋势及其预报

本文利用内蒙古1961～2001年的天气气候资料,对内蒙古中西部地区沙尘暴作了统计分析,阐述了沙尘暴的危害并给出了沙尘暴的基本定义。分析了引起沙尘暴的天气和气候因子的变化趋势,研究了他们对沙尘暴的影响,结果表明近40年内蒙古的沙尘暴总体呈减少趋势,但从1998年开始有所增加;沙尘暴的空间分布以阿拉善盟偏北地区为最高发区;降水、气温、大风、寒潮、北半球极涡、西太平洋副热带高压、亚洲西风环流、东亚大槽和南方涛动等天气和气候因素均对该地区沙尘暴的发生有不同程度的影响。