β-羟丁酸抑制脂多糖诱导奶牛中性粒细胞核因子-κB信号通路的激活

高酮血症造成奶牛中性粒细胞先天免疫机能受到抑制,本研究探讨β-羟丁酸(BHBA)是否抑制脂多糖(LPS)诱导的奶牛中性粒细胞核因子-κB(NF-κB)信号通路的激活。分离健康奶牛中性粒细胞,采用LPS(100 ng/mL)和不同浓度(0.5、1.0、2.0和4.0 mmol/L)BHBA作用于中性粒细胞,收集细胞,应用实时荧光定量PCR(qRT-PCR)检测中性粒细胞中白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)和NF-κBp65 mRNA表达水平,Western blot检测NF-κBp65蛋白表达水平,比色法检测核因子-κB抑制物激酶β(IKKβ)激酶活性,酶联免疫吸附试验(ELISA)法检测促炎细胞因子TNF-α、IL-6和IL-1β的分泌量。结果表明:与对照组(不进行BHBA和LPS处理)相比较,LPS组(单独LPS处理)中IL-1β、IL-6、TNF-α和NF-κBp65 mRNA表达水平和NF-κBp65蛋白表达水平极显著增加(P <0.01),IKKβ激酶活性极显著增强(P<0.01),IL-1β和TNF-α的分泌量极显著增加(P<0.01),IL-6的分泌量显著增加(P <0.05)。与LPS组相比,0.5、1.0、2.0和4.0 mmol/L BHBA均使IL-1β、IL-6、TNF-α和NF-κBp65 mRNA表达水平和NF-κBp65蛋白表达水平显著或极显著增加(P<0.05或P<0.01),IKKβ激酶活性显著或极显著增强(P<0.05或P<0.01),IL-1β、IL-6和TNF-α的分泌量显著或极显著增加(P<0.05或P<0.01)。以上结果表明,高浓度BHBA可以抑制LPS诱导的奶牛中性粒细胞NF-κB信号通路的激活,具有一定的抗炎功能。     

原子吸收分光光度法测定人发痕量镉的研究

以硝酸—高氯酸为消化液,消解人发试样,采用碘化钾—甲基异丁酮萃取发样中的镉,采用原子吸收分光光度法,将有机相喷雾测定。并且对直接法、标准加入法和原子吸收分光光度法进行了比较。本测定方法 C? V小于 3.1%,标准加入回收率在 95.6%～103.2%之间,结果可靠,适用于人发中痕量镉的测定。     

贵州十大名茶中茶多糖的含量分析

为了解贵州十大名茶中茶多糖的含量,为茶叶的种植、加工及质量综合评价提供理论依据,采用水提法提取茶多糖、蒽酮-硫酸法比色测定茶多糖含量的方法,对贵州十大名茶中茶多糖的含量进行了系统的研究。结果:富硒绿茶的茶多糖含量最高,为2.67%;遵义毛峰的茶多糖含量最低,为1.11%。表明,贵州十大名茶中茶多糖的含量与其品种及产地有着密切的关系。     

过瘤胃氯化胆碱在奶牛上的应用研究进展

高产奶牛在产后泌乳初期体内常出现能量供应负平衡状态,继而引发如脂肪肝、酮病等一系列营养代谢性疾病。在产后奶牛日粮中外源适量添加过瘤胃氯化胆碱(rumen-protected choline, PRC)能改善血液生化指标,提高奶牛生产性能。作者综合了过瘤胃氯化胆碱的有关文章和试验,简要综述了其在奶牛上应用的研究进展。     

酮粉法检测泌乳牛尿酮乳酮的应用研究

荷斯坦泌乳牛尿、乳酮体的酮粉法定性试验表明：尿酮阳性率为29．25％，乳酮阳性率为10％。尿、乳阳性牛的血酮、血糖、乳酮、尿酮定量测定表明：酮粉法判定泌乳奶牛亚临床酮病，尿酮阳性反应具有早期、敏感、准确性低的特点。乳酮阳性反应具有准确、敏感性低、方便等特点。二者同时定性检测具有互补作用。     

Titanium dioxide photoinduced degradation of some pesticide/fungicide precursors

Five-membered nitrogen heterocycles (pyrrole, imidazole and 1,2,4-triazole) have been degraded using titanium dioxide and simulated solar radiation at pH = 8. The degradations followed a simple Langmuir-Hinshelwood mechanism. Accordingly, the adsorption equilibrium constants K of the heterocycles on the titanium dioxide surface and the rate constants k of degradation of the heterocycle-catalyst adduct have been obtained experimentally. While the K values decrease with heterocycle pKa, the k values increase with increasing pKa. Therefore, apparently, the rate constant depends on the availability of the electron pair on nitrogen, but at the same time the electron pair repulsion induced by the negatively charged titanium dioxide surface at pH = 8 causes a reverse effect in the adsorption equilibrium constant. Only in the case of imidazole, where the adsorption equilibrium constant is low enough (K = 0.013 M(-1)), can the rate constant be approximated to a pseudo-first-order rate expression: k(obs) = Kk. In all other cases, k(obs) = Kk/(1 + K(heterocycle)).     

Inhibition of juvenile hormone biosynthesis and methyl farnesoate epoxidase activity by 1,5-disubstituted imidazoles in the cockroach,Diploptera punctata

Seventeen substituted imidazoles were tested as inhibitors of juvenile hormone (JH) III synthesis by cockroach corpora allata in an in-vitro radio-chemical assay. Most of these 1,5-disubstituted imidazoles were highly potent, with IC₅₀ values of less than 100nM. The compounds differed in their ability to cause an accumulation of the precursor methyl farnesoate in the glands. Four of the imidazoles were tested by topical application to previtellogenic adult females, and all caused a significant inhibition of JH synthesis and an accumulation of intraglandular methyl farnesoate for at least three days after treatment. Methyl farnesoate epoxidase activity of homogenates of corpora allata was inhibited by the compounds TH -14 and TH -27. This P450-dependent epoxidase activity was inhibited at less than 10 nM. The results show that the 1,5-disubstituted imidazoles are powerful inhibitors of the last step of juvenile synthesis in this cockroach.     

清甜型香料西瓜酮的合成研究及在烟草中的应用

综述了西瓜酮合成的研究进展,在此基础上总结得出了以4-甲基邻苯二酚和1,3-二氯丙酮一步法合成西瓜酮的工艺。与其他方法相比,该合成方法工艺简单、得率高。同时,探讨了西瓜酮在烟草中的应用及其对卷烟烟气的改善作用。     

贵州地区黑白花奶牛酮病的调查

通过人用血糖/血酮仪测试80头黑白花奶牛泌乳期血酮水平,分析血酮水平与胎次、泌乳月及日产奶量的关系,对贵州地区奶牛酮病作出初步调查研究.结果表明,贵州地区临床型奶牛酮病发病率为2.5%,亚临床型奶牛酮病发病率为12.5%;各胎次血酮水平无显著差异;第1泌乳月血酮水平显著高于第3以上泌乳月血酮水平;日产奶量在30kg以上时,血酮水平显著升高,奶牛处于亚临床型酮病状态.     

超高效液相色谱—串联质谱法测定牛奶中6种玉米赤霉烯酮类霉菌毒素的残留

试验旨在建立牛奶中6种玉米赤霉烯酮类霉菌毒素残留的超高效液相―串联质谱检测方法。牛奶样品经乙腈提取,免疫亲和柱净化,C₁₈色谱柱分离,以0.02%（V/V）乙酸―水/甲醇为流动相,采用梯度洗脱方式进行液相色谱分离,多反应监测模式,外标法进行定量。牛奶中6种玉米赤霉烯酮类霉菌毒素的检测限可达到1.0 μg/L,且在2.5～100.0 μg/L的浓度范围内,线性关系良好。该方法专属性强、灵敏度高、分离度好,适用于牛奶中的6种玉米赤霉烯酮类霉菌毒素残留的测定。