反相高效液相色谱法同时测定四维钙片中多种维生素含量

目的对四维钙片中的维生素C（VitC）、维生素B1（vitB1）及维生素B2（VitB2）进行含量测定。方法采用反相高效液相色谱法，使用Zorbax Eclipse XDB—C8柱（150mm×4．6mm，5μm），流动相为0．05％乙酸溶液（含0．005mol／L己烷磺酸钠、1．3％三乙胺，用冰醋酸调节pH值至3．5）-甲醇（90：lO），检测波长为254nm。结果VitC，VitB1，，VitB2质量浓度分别在7～60μg／mL，1～10μg／mL，1～10μg／mL范围内与峰面积线性关系良好，r分别为0．9998，0．9997，0．9998（n=8）；平均回收率分别为100．3％，99．1％，98．5％，RSD分别为1．2％．1．5％．1．6％（n=9）。结论该方法准确、简单,能够有效控制制剂的质量。     

Effects of ozone on DNA single-strand breaks and 8-oxoguanine formation in A549 cells

Animal studies have demonstrated that ozone exposure can induce lung tumors. Recent epidemiological studies have also shown that increased ozone exposure is associated with a greater risk of lung cancer. This study used single-cell gel electrophoresis (the Comet assay) and flow cytometry to investigate DNA damage in A549 cells exposed to ozone levels below the current ambient standard. Cells were exposed to ozone at levels of 0, 60, 80, and 120 ppb, and then DNA single-strand breaks and 8-oxoguanine levels were measured. Additionally, the formamidopyrimidine glycosylase (Fpg) repair enzyme was added to the Comet assay to enhance detection of oxidative damage. Vitamins C and E were also added to determine their inhibitory effects on ozone-induced 8-oxoguanine. Measurements of tail length, tail intensity, and tail moment of the Comet assay were shown to correlate with each other. However, tail moment appeared to be more sensitive than the other two indicators in detecting DNA single-strand breaks. Tail moments of cells exposed to 80 and 120 ppb of ozone were significantly higher than those exposed to 0 ppb (P<0.05). These three indicators of DNA single-strand breaks with Fpg were shown to be increased and more sensitive than those without Fpg. After Fpg was introduced, the tail moments at ozone levels of 60, 80, and 120 ppb were significantly higher than those at 0 ppb (P<0.05). Furthermore, 8-oxoguanine levels, determined by fluorescence intensity, at 80 and 120 ppb of ozone exposure were significantly higher than the level at 0 ppb. Pretreatment with vitamins C and E reduced the 8-oxoguanine levels caused by ozone. We conclude that ozone levels below current ambient standards may induce DNA breaks and oxidative DNA damage. Moreover, the Fpg repair enzyme in the Comet assay can increase the sensitivity of oxidative damage detection in vitro.     

初乳中活性营养成分分析

利用免疫学技术和生化分析手段，研究人初乳中大分子活性物质和小分子营养物质。结果提示：（1）人初乳中SlgA含量很高，达10mg／ml；（2）人初乳中含有两类生长因子成份，一类对颈基乙醇稳定，一类对流基乙醇不稳定，而人成乳和牛初乳只具备一种类型的生长因子；（3）人初乳中蛋白质氨基酸含量丰富，尤其富含八种必需氨基酸。维生素A、D、E及矿质元素Ca、P、Fe的含量均高于某些代乳品，且配比合理，营养评分较高。结果阐明人初乳对新生地具有保护和营养两方面功能。     

Critical reappraisal of vitamins and trace minerals in nutritional support of cancer patients

The potential of a high intake of fresh fruits and vegetables in cancer prevention is well established. Epidemiological studies support carotene, vitamins A, C, E and selenium as the active compounds. Antioxidant properties and direct effects (e.g. inhibition of N-nitrosamine formation or cell-to-cell interactions) are invoked. The role of other trace elements is less clear. The modulation of immune function by vitamins and trace elements remains important and affects survival. In established cancers, the site-specific differences in the diet/cancer relation require appropriate dietary changes, e.g. low fat (20% by energy) in breast cancer, or high vegetable or fruit intake in lung cancer. Single high-dose supplements (e.g. vitamin C) have proved to have no curative or life-prolonging effect. Chemotherapy and radiation increase the requirements for antioxidant compounds. Supplementation can diminish the damage induced by peroxidation. Carefully planned and monitored trials that establish the optimal intake of micronutrients as adjuvants in cancer patients are required.Presented as an invited lecture at the 4th International Symposium: Supportive Care in Cancer, St. Gallen, Switzerland, 24–27 February 1993     

5-methyltetrahydrofolic acid stimulates endothelin-1 production in low density lipoprotein-treated human endothelial cells

Background and aimsSeveral studies have shown the beneficial effects of folate treatment in improving cardiovascular function. However, the mechanisms involved have not been clearly identified. The aim of this study is to determine the effect of folates and vitamin B₁₂ on endothelial vasoconstriction/vasodilatation parameters in cultured human endothelial cells incubated with human low density lipoproteins (LDL).Methods and resultsHuman umbilical vein endothelial cells (HUVEC) were extracted from recently delivered umbilical cords, cultured until confluence was achieved, and then incubated for 24 h with folic acid (FA), 5-methyltetrahydrofolic acid (5-MTHF) or vitamin B₁₂ (B₁₂) in the presence or absence of LDL that was isolated from healthy volunteers. Total nitrites (as a measure of nitric oxide production), thiobarbituric acid reactive species (TBARS, a parameter of lipid peroxidation), and endothelin-1 (ET-1) were determined in the incubation media. None of the vitamins, either in the presence or absence of LDL, was able to modify nitric oxide production by HUVEC. A significant reduction of ET-1 production was observed in LDL-treated cells. This effect was not modified by FA or B₁₂; however, 5-MTHF caused a concentration-dependent increase on ET-1 production, an effect coincidental with reduced TBARS production.ConclusionsThis study demonstrates for the first time that 5-MTHF, but not FA or B₁₂, increases ET-1 production in LDL-treated endothelial cells. Although this effect was associated with the antioxidant properties of this folate, our results show that additional specific mechanisms involving 5-MTHF-LDL interactions may be operating to regulate endothelial function.     

Effects of nutrients on immunomodulation in patients with severe COVID-19: Current knowledge

Recent research has demonstrated that critically ill patients with coronavirus disease 2019 (COVID-19) show significant immune system dysregulation. Due to that, some nutrients that influence immunomodulation have been suggested as a form of treatment against the infection. This review collected the information on the impact of vitamins on the prognosis of COVID-19, with the intention of facilitating treatment and prevention of the disease risk status in patients. The collected information was obtained using the PubMed electronic database by searching for articles that relate COVID-19 and the mechanisms/effects of the nutrients: Proteins, glucose, lipids, vitamin B12, vitamin D, calcium, iron, copper, zinc, and magnesium, including prospective, retrospective, and support articles. The findings reveal an optimal response related mainly to omega-3, eicosapentaenoic acid, docosahexaenoic acid, calcium, and iron that might represent benefits in the treatment of critically ill patients. However, nutrient supplementation should be done with caution due to the limited availability of randomized controlled studies.     

Antioxidants: Benefits and risks for long-term health

The oxidative modification hypothesis postulates that oxidative stress is one of the major factors in aging and the development of age-related disorders, including cardiovascular diseases. In this scenario, the oxidative modification of lipids, proteins and nucleic acids in vascular walls contributes to the etiology of cardiovascular disease, implying that consumption or therapeutic use of antioxidants could prevent the onset of such pathological disorders. Because of this, a number of studies have been conducted to address the question of whether cardiovascular diseases can be modulated by antioxidant treatment or consumption. Although some of the earliest data, collected in animal studies and epidemiologic studies have shown a measure of success, numerous clinical trials indicate that this approach is of minimal or no benefit. These conclusions represent a challenge to design more sensitive antioxidant trials in order to confirm or alter these conclusions. The focus of this review is on the benefits and disadvantages associated with the use of antioxidants, such as vitamins C and E, polyphenols, or antioxidant therapies, including hormone replacement therapy and iron reduction therapy, on overall vascular health.     

Validation of a self-administered diet history questionnaire using multiple diet records

The validity of a self-administered diet history questionnaire has been estimated using as the reference data the mean of three 4-day diet records collected over the year prior to the administration of the questionnaire, in 1985–1986. Subjects were women ages 45–70 years, participants in the Women's Health Trial Feasibility Study, a multi-center clinical trial in which some women were randomized to be taught to adopt and maintain a low-fat diet, while others maintained their usual diet. The questionnaire produced group mean nutrient estimates closely approximating the values obtained by three 4-day records, e.g. in the usual-diet group, 37.7% of calories from fat by both food records and by questionnaire, and in the low-fat, group, 21.3% of calories from fat by food records and 23.7% of calories from fat by questionnaire. Correlations between questionnaire and diet records for per cent of calories from fat were 0.67 and 0.65 respectively in the two groups; most correlations were in the 0.5–0.6 range, and were similar to those achievable by a single 4-day food record.     

腹腔感染后维生素A、E、C代谢障碍的防治

目的观察完全胃肠外营养(TPN)添加维生素A、E、C对腹腔感染后抗氧化能力的影响。方法采用盲肠结扎加穿孔(CLP)模型,将SD大鼠随机分为对照组(CLP TPN)、治疗组(CLP TPN 维生素A、E、C)、延迟治疗组(CLP TPN 延迟应用维生素A、E、C),于术后当天以及第1、3、5天观察血浆及肝组织中维生素含量及丙二醛(MDA)、还原型谷胱甘肽(GSH)的变化。结果 CLP对照组维生素A、E、 C及GSH明显低于正常对照,MDA显著高于正常对照;治疗组和延迟治疗组维生素A、E、C及GSH显著高于对照组,但延迟治疗组低于治疗组;治疗组和延迟治疗组MDA明显低于对照组,但延迟治疗组高于治疗组。结论 TPN添加维生素A、E、C能改善腹腔感染后机体的抗氧化能力,减轻脂质过氧化损伤。