1Alpha,25-dihydroxyvitamin D3 inhibits hepatic chromosomal aberrations, DNA strand breaks and specific DNA adducts during rat hepatocarcinogenesis

The possible promoting effect of streptozotocin (STZ; 65 mg/kg body weight, intraperitoneal)-induced diabetes during 2-acetylaminofluorene (2-AAF; 0.04% in basal diet)-initiated hepatocarcinogenesis and modulatory effect of 1α,25-dihydroxyvitamin D₃ (VD₃; 0.3 μg/0.1 ml in propylene glycol, per os) were investigated by monitoring chromosomal aberrations (CAs), DNA strand breaks and specific DNA adducts in rat liver. VD₃ treatment (twice a week) was started 4 weeks before the 2-AAF regimen and continued throughout the study. Aberrant metaphase chromosomes were counted from the regenerating hepatocytes 15, 30 or 45 weeks after STZ injection, while DNA strand break and adduct assays were performed 45 days post-STZ treatment. Dietary exposure to 2-AAF elicited a substantial increase in CAs and elevated the extent of DNA strand breaks and formation of N-(deoxyguanosin-8-yl)-2-aminofluorene. A promoting effect of STZ was evident from CAs coupled with DNA strand break analysis. VD₃ treatment substantially reducted 2-AAF+STZ-induced CAs as well as DNA strand breaks and adducts. Thus, VD₃ appears to be effective in suppressing liver-specific early chromosomal as well as DNA damage during the process of rat hepatocarcinogenesis initiated with 2-AAF and promoted by STZ contributing to its promise as a cancer chemotherapeutic agent. Received 27 April 2001; accepted 22 May 2001     

两点电位滴定法测定维生素B6的含量

提出了用两点电位滴定法测定维生素B6含量的新方法,只需记录两次终点附近的AgNO3标准溶液的体积和相应电极电位值,即可利用两点法公式计算出终点体积,从而确定维生素B6含量。     

高效液相色谱法同步测定花粉中的水溶性维生素

采用液相色谱法同步测定花粉中的水溶性维生素C(VC)、维生素B1(VB1)、维生素B2(VB2)和维生素B5(VB5),四种维生素在ODS-5μm色谱柱上分离,用pH5.01的磷酸缓冲液-甲醇(体积比为7525)为流动相洗脱,流速为1.0ml@min-1,波长为260nm,10min内实现良好分离.在(1～20)×10-6范围内进样量和响应值呈良好线性关系.其回收率为94.37%～101.57%,变异系数为1.90%～8.23%,精密度和准确度良好.为快速、准确地同步测定花粉中的水溶性维生素提供了一种新的方法.     

利用毛细管电泳仪测定B 族维生素含量最佳电泳条件的探讨

探讨毛细管电泳对Ｂ族维生素的分离分析的最佳电泳条件,结果表明：胶束电动力学毛细管色谱是分离分析Ｂ族维生素的一种有效的毛细管电泳操作模式;不同缓冲液及其ＰＨ对分离造果影响很大,１００ｍｍｏｌ／Ｌ硼酸钠缓冲液（ＰＨ８．５）比较适合Ｂ族维生素的分离分析;毛细管温度、运行电压对分离也有较大影响,在３５ｃｍ＊５０μｍ未涂渍石英毛细管条件下,采用ＰＨ８．５,附加５０ｍｍｏｌ／Ｌ ＳＤＳ对分离也有较大影响,在３     

汉中仙毫茶多酚与维生素C抗氧化及抑菌活性的协同作用

采用DPPH·和ABTS⁺·方法研究了汉中仙毫茶多酚与维生素C(VC)体外抗氧化活性的协同作用,采用二倍稀释法和牛津杯法研究了茶多酚与VC混合物对大肠杆菌的抑菌作用。茶多酚与VC的混合物[m(茶多酚)∶m(VC)=1∶1,1∶2,2∶1]具有较强的DPPH·清除能力,其EC₅₀值低于茶多酚和VC；并且混合物中VC所占比例越高,EC₅₀值就越低。m(茶多酚)与m(VC)的1∶1混合物对ABTS⁺·的EC₅₀值略低于VC。基于体外抗氧化活性与样品浓度之间量效关系构建的数学模型具有较高的拟合度。m(茶多酚)与m(VC)的1∶1和2∶1混合物对大肠杆菌的最小抑菌浓度分别为38和46mg·mL-1。m(茶多酚)与m(VC)的2∶1混合物的抑菌圈直径较大,其抑菌活性略高于茶多酚。茶多酚与VC以特定比例混合后,自由基清除能力有所提高,并且抑菌活性有明显的提升。     

刺梨的炮制及其炮制品中维生素C测定法

目的：以微波干燥技术探索刺梨炮制方法,并建立刺梨炮制品中维生素c的RP—HPLC含量测定方法。方法：以1％偏磷酸为提取溶剂,分析柱为迪马C18柱（4．6mm×250mm,5um）,检测波长245nm,柱温：30℃;为流动相：0．1mol／L磷酸二氢钾-甲醇（97：3）,流速1．0mL／min。结果：在79．24ug／m...     

维生素对红法夫酵母产虾青素的影响

采用单因素实验方法研究了不同维生素对红法夫酵母(Phaffia rhodozyma)生长及虾青素积累的影响.结果表明:生物素、泛酸钙、肌醇、VB1可显著提高红法夫酵母的生物量、类胡萝卜素和虾青素的产量,其较适质量浓度分别为0.05,25.00,0.50,0.05 mg/L.VB12和核黄素对红法夫酵母的细胞生长有明显的促进作用,同时可略微提高虾青素产量,其较适质量浓度分别为0.50和0.005 mg/L;VB6、烟酸和叶酸虽然可促进细胞生长,但却明显抑制了虾青素的积累;而硫辛酸既抑制细胞生长也抑制其虾青素的积累.根据单因素实验结果,在培养基中按以上较适浓度添加生物素、泛酸钙、肌醇、VB1、VB12和核黄素,菌体生物量和虾青素质量浓度分别达到5.000 g/L和16.77 mg/L,较对照组分别提高了33.2%和108%.     

维生素E和硒对正常及其恶性细胞增殖的联合作用

为进一步评价补充维生素Ｅ和硒的安全性，本文以正常仓鼠幼肾成纤维细细胞株及其多瘤病毒转化的恶性细胞株为对象，探讨了不同浓度的维生素Ｅ和硒对该对细胞增殖情况的单独和联合作用。结果显示：７μｍｏｌ／Ｌ的维生素Ｅ使ＢＨＫ－２１／ｃ１３和ＢＨＫ－２１／ＰｙＹ细胞株在９６ｈ的细胞计数分别增加１１％和１６％；０．１μｍｏｌ／Ｌ的亚硒酸钠对上述二株细胞的增殖无影响；同时补充以上相同浓度的维生素Ｅ和亚硒酸钠，９６ｈ     

Chemical evidence for interactions between vitamins E and C

Summary Experimental proof is provided for interactions between radicals of vitamin E/vitamin C as generated by air-oxidized lipids (liquid fraction of subcutaneous chicken fat). Using ESR spectroscopy, hydrogen atom exchange is shown to take place between vitamin C and the radical of vitamin E. Sequential consumption of these two vitamins in oxidized lipid, first vitamin C then vitamin E, is demonstrated by means of differential pulse polarography. These results elucidate the in vitro radical scavenging functions attributed to vitamin E and vitamin C as well as their synergism in lipid antioxidation.The authors very much thank Dr A. Dieffenbacher and P. Ducret for the preparation of the chicken fat fraction.     

Local action of vitamin A on amphibian limb regeneration

Summary Axolotl forearms isolated from upper arm tissue either surgically or by local irradiation regenerate excessive structures after vitamin A treatment. This demonstration excludes the possibility of regeneration being altered by enhanced cellular migration and thus indicates that vitamin A respecifies cells close to the site of amputation.