维生素是怎样发现的

维生素是怎样发现的冯德和（辽宁锦州市第一师范学校１２１００１）维生素是营养素中发现最晚的一类,它的发现改变了人类的饮食方式,也改变了人们对疾病的认识,避免了众多维生素缺乏症的困扰。维生素的发现是生物史上一个重要的里程碑。人类对维生素的认识,总体来说经...     

高等植物维生素C和维生素E代谢调控

维生素C和维生素E是植物自身合成的抗氧化剂,对植物发育具有重要调控作用。本文对近年来高等植物维生素C和维生素E合成途径、代谢调控、关键酶基因的克隆和转化进行了论述,分析两种维生素之间的相互作用,对该领域未来的研究方向进行了展望。     

脂溶性维生素A、D、E与妊娠期糖尿病的相关性分析

目的:探讨妊娠期糖尿病(gestational diabetes mellitus,GDM)孕妇血清中维生素A、25-羟基维生素D、维生素E的水平及其临床意义。方法:选取在大连大学附属中山医院就诊并诊断为GDM的孕妇1000例为实验组;另选取无GDM孕妇1000例为对照组。采用反向高频液相色谱荧光法(high-performance liquid chromatography,HPLC)测定其血清维生素A、E水平;高效液相色谱液相色谱串联质谱法(high-performance liquid chromatography tandem mass spectrometer,HPLC-AS/MS)测定血清25-羟基维生素D水平。结果:GDM孕妇血清中维生素A水平与无GDM孕妇比较差异无统计学意义(P>0.05);GDM孕妇血清25-羟基维生素D水平明显低于对照组(P<0.05);GDM孕妇血清维生素E水平明显高于对照组(P<0.05)。GDM孕妇血清25-羟基维生素D水平与血清维生素E水平呈显著负相关(r=-0.351,P<0.05)。结论:GDM孕妇血清25-羟基维生素D水平低,维生素E水平高,且两者有一定相关性,可能共同参与了GDM的发生。     

百年寻觅维生素

维生素的种类很多,这也决定了维生素的发现不可能由一个或一个研究小组完成。事实上,人类对于维生素的认识是一个漫长的过程,其中凝结着许多人的心血与智慧。     

百年寻觅维生素

<正>维生素的种类很多,这也决定了维生素的发现不可能由一个人或一个研究小组完成。事实上,人类对于维生素的认识是一个漫长的过程,其中凝结着许多人的心血与智慧。     

代谢工程在维生素生产中的应用及研究进展

维生素是维持人体生命活动必需的一类有机物质,机体本身一般不能合成或合成量不足,因此需经食物或其他强化产品获取。目前,维生素产品已广泛应用于医药、食品添加剂、饲料添加剂、化妆品等领域,而且全球对维生素的需求也是呈逐年增长态势。维生素的生产方法主要包括化学合成法和生物合成法。化学合成法通常安全隐患大、反应条件严苛、废物污染严重,相比之下,代谢工程生产维生素绿色环保安全、能耗低,因此建立微生物细胞工厂具有重大的科学意义和应用需求。文中回顾了近30年来代谢工程在维生素生产领域的研究进展,详细阐述了水溶性维生素(维生素B1、B2、B3、B5、B6、B7、B9、B12和维生素C的前体)和脂溶性维生素(维生素A、维生素D的前体、维生素E和维生素K)的生物合成研究现状,并对其发酵生产的瓶颈进行了探讨,最后对合成生物技术创建维生素生产菌种进行了展望。     

植物维生素E代谢工程研究

维生素E是一种脂溶性维生素,仅在光合细菌和高等植物中合成,是人体中必不可少的一种营养物质,具有重要的生物学功能。维生素E合成代谢研究一直受到人们的关注,已通过生物信息学及转基因技术完成了维生素E合成代谢关键酶基因的分离及功能鉴定,近来研究重点转移到利用代谢工程方法提高植物维生素E含量与活性上来。综述了维生素E合成代谢途径及其代谢工程的研究现状,并对未来维生素E代谢工程研究提出了展望。     

植物维生素E合成及其生物技术改良

维生素E是一种抗氧化剂 ,对植物、动物和人类自身都具有十分重要的作用 ,而植物则是人类维生素E的主要来源 ,因此克隆植物中维生素E合成的相关酶基因 ,对维生素E含量进行改良 ,具有重要意义。对植物中维生素E的合成途径 ,相关酶基因的克隆以及用生物技术的方法对维生素E含量进行遗传改良进行了综述。     

北京市中小学生维生素D水平与血脂异常的相关性研究

目的：探讨北京市中小学生血清维生素D水平与血脂异常的相关性。 方法：数据来源于2015年北京市中小学生营养与健康状况监测。采用多阶段分层整群抽样方法于北京市3个城区、4个郊区每区选取小学、初中各4所学校共3 566名中小学生进行调查。抽取静脉血检测维生素D和血生化指标等,采用二元Logistic回归模型分析血清维生素D不足和缺乏对血脂异常发生风险的影响。 结果：在3 566名中小学生中,血脂异常的有735人（20.6%）,维生素D不足的有947人（26.6%）,维生素D缺乏的有824人（23.1%）。二元Logistic回归模型在调整了年龄、性别、地区、体型、尿酸和空腹血糖变量后,发现维生素D不足和维生素D缺乏对总血脂异常发生的风险没有影响;而与维生素D适宜者相比,维生素D不足降低了TC异常发生的风险,增加了TG异常发生的风险;与维生素D适宜者相比,维生素D缺乏降低了TC异常和LDL C异常发生的风险,增加了HDL C异常发生的风险。结论：北京市中小学生血脂异常、维生素D不足和缺乏的情况均较为严重,需引起重视;在该研究样本中,维生素D不足和缺乏对总血脂异常的发生风险没有影响;维生素D不足降低了TC异常发生的风险,增加了TG异常发生的风险;维生素D缺乏降低了TC异常和LDL C异常发生的风险,增加了HDL C异常发生的风险。维生素D与血脂异常的关系仍需进一步的研究加以证实。     

维生素D及其受体在帕金森病中的作用

帕金森病(Parkinson's disease,PD)是一种常见的中枢神经系统退行性疾病,引起帕金森病的发病机制至今尚未明确。帕金森病患者及老年人普遍存在维生素D缺乏,这可能是帕金森病的重要发病机制之一。由于维生素D具有免疫调节,抗氧化,调节神经营养因子,降低神经毒性的功能,能同时针对几种导致神经退行性病变因素发挥作用,特别是老年人纠正维生素D缺乏可能会阻止神经元的损失和PD相关的认知功能下降。因此补充维生素D可能成为治疗PD的方法。近年来研究发现,维生素D受体基因多态性与帕金森病的发病有相关性。该文就维生素D及其受体在帕金森病中可能发生的保护作用及其机制作一综述。     

Observations from the UK Supra-Regional Assay Service laboratory for the measurement of Vitamin D metabolites

As a Supra-Regional Assay Service (SAS) laboratory, we receive samples from all over the UK. Of these some are sent frozen and others by post or courier. We have examined transport and storage conditions to see whether they affect the measurement of Vitamin D metabolites and potentially contribute to the variation in measurement of 25-hydroxyvitamin D (25OHD) seen in the DEQAS scheme. We have also examined the samples received during 2005. We found that different transport and storage conditions did not contribute significantly to the normal variation seen in measuring Vitamin D metabolites (CV% (±S.E.) for stored versus assay controls: 5.1 ± 0.06% versus 4.5 ± 0.04% for 25OHD and 10.8 ± 1.0% versus 12.3 ± 1.0% for 1,25D). A review of the service showed a 240% increase in samples received over the last 5 years. Despite an increased awareness of the need to measure Vitamin D status, in this cross-section of patient samples 92% of Asian and 86% of white patients were found to be Vitamin D-insufficient (<30 ng/ml) and 27% of Asian and 14% of white patients were profoundly deficient (<5 ng/ml) and at risk of bone disease.     

Complexity of vitamin E metabolism

Bioavailability of vitamin E is influenced by several factors, most are highlighted in this review. While gender, age and genetic constitution influence vitamin E bioavailability but cannot be modified, life-style and intake of vitamin E can be. Numerous factors must be taken into account however, i.e., when vitamin E is orally administrated, the food matrix may contain competing nutrients. The complex metabolic processes comprise intestinal absorption, vascular transport, hepatic sorting by intracellular binding proteins, such as the significant α-tocopherol-transfer protein, and hepatic metabolism. The coordinated changes involved in the hepatic metabolism of vitamin E provide an effective physiological pathway to protect tissues against the excessive accumulation of, in particular, non-α-tocopherol forms. Metabolism of vitamin E begins with one cycle of CYP4F2/CYP3A4-dependent ω-hydroxylation followed by five cycles of subsequent β-oxidation, and forms the water-soluble end-product carboxyethylhydroxychroman. All known hepatic metabolites can be conjugated and are excreted, depending on the length of their sidechain, either via urine or feces. The physiological handling of vitamin E underlies kinetics which vary between the different vitamin E forms. Here, saturation of the side-chain and also substitution of the chromanol ring system are important. Most of the metabolic reactions and processes that are involved with vitamin E are also shared by other fat soluble vitamins. Influencing interactions with other nutrients such as vitamin K or pharmaceuticals are also covered by this review. All these processes modulate the formation of vitamin E metabolites and their concentrations in tissues and body fluids. Differences in metabolism might be responsible for the discrepancies that have been observed in studies performed in vivo and in vitro using vitamin E as a supplement or nutrient. To evaluate individual vitamin E status, the analytical procedures used for detecting and quantifying vitamin E and its metabolites are crucial. The latest methods in analytics are presented.     

Plasma alpha-tocopherol, retinol, cholesterol, and mineral concentrations in captive gorillas

Vitamins A, E, cholesterol, and mineral (calcium, copper, iron, magnesium, phosphorus, selenium, sodium, and zinc) concentrations were examined in the plasma of 74 captive lowland gorillas aged newborn to 41 years. Effects of age or sex on measured parameters were not significant. Plasma Mg and Ca concentrations were lower than reported captive gorilla means, whereas Na and P were higher. Since comparative gorilla values for certain blood components (vitamins E and A, copper, and selenium) are lacking, normal human values may provide the best available indicators for evaluating the plasma levels of these components in gorillas.     

Vitamin D in foods and as supplements

Numerous studies have shown that the vitamin D status is far from optimal in many countries all over the world. The main reason for this is lack of sunshine. Only a limited number of foods naturally contain vitamin D. Good sources of vitamin D(3) are fish (not only fatty fish), egg yolk, and offal such as liver. Some foods such as milk are fortified with vitamin D in some countries. Dietary vitamin D intake is low in many countries, especially as the dietary sources are limited. The use of supplements is important and seems to be high in some countries. Current dietary intake recommendations are too low to preserve/reach optimal S-25-OHD concentrations, when UVB radiation is not available. We suggest that the recommendations should be increased to at least 10 microg per day in all age groups when solar UVB is scarce. The elderly may need a daily vitamin D intake of 25 microg. If dietary intake of vitamin D is to be increased, food habits will have to change. From a public health point of view it is better to increase the potential sources of vitamin D by fortifying specific products that are consumed commonly in a whole population, or if necessary by especially vulnerable groups. Supplement use is probably the right alternative for vulnerable groups such as infants and inactive elderly in whom this is more easily implemented.     

Vitamin D status and nutrition in Europe and Asia

Vitamin D status is highly different in various countries of Europe, the Middle East and Asia. For this review, vitamin D deficiency is defined as serum 25-hydroxyvitamin D (25(OH)D) <25 nmol/l. Within European countries, serum 25(OH)D is <25 nmol/l in 2–30% of adults, increasing in the elderly and institutionalized to more than 80% in some studies. A north-south gradient was observed for serum 25(OH)D in the Euronut and MORE studies with higher levels in Scandinavia and lower levels in Italy and Spain and some Eastern European countries. This points to other determinants than sunshine, e.g. nutrition, food fortification and supplement use. Mean vitamin D intake in Scandinavia is 200–400 IU/d, twice that in other European countries. Very low serum 25(OH)D levels have been reported in the Middle East, e.g. Turkey, Lebanon, Jordan and Iran. In these countries serum 25(OH)D was lower in women than in men and associated with clothing habits. In a Lebanese survey, vitamin D deficiency was observed in the majority and occurred mainly in veiled women. In India, vitamin D deficiency was observed in more than 30%, vitamin D status being poor in school children, pregnant women and large cities. Vitamin D status was much better in Malaysia and Singapore, but lower serum 25(OH)D was observed in Japan and China. Rickets and osteomalacia appear quite common in India, but precise data are lacking. Immigrants in Europe from the Middle East and Asia carry a high risk for vitamin D deficiency, pregnant women being especially at risk. Comparison of vitamin D status between countries is hampered by interlaboratory variation of serum 25(OH)D measurement. In addition, there is a need of population-based data. In conclusion, vitamin D deficiency is common in Southern Europe, the Middle East, India, China and Japan. It is less common in Northern Europe and Southeast Asia. Risk groups are young children, the elderly, pregnant women and non-western immigrants in Europe. Important determinants are skin type, sex, clothing, nutrition, food fortification, supplement use, BMI and degree of urbanization.     

Effects of alpha tocopherol and ascorbic acid on Helicobacter pylori colonization and the severity of gastric inflammation

Background and Aim: We aimed to evaluate the changes in histopathologic features, concentrations of vitamins C and E in gastric mucosa, and total antioxidant capacity of the body after ingestion of ascorbic acid and alpha tocopherol in patients with Helicobacter pylori. Material and Method: Patients with H. pylori‐positive nonulcer dyspepsia were included in this study. Tissue samples were taken from the lesser and greater curvature in both prepyloric antrum and corpus for histopathologic examination and measurement of vitamins C and E concentrations. Blood samples were obtained for measurement of the total antioxidant capacity of the body. The patients were given vitamin C 500 mg BID and vitamin E 200 IU BID for 4 weeks orally. At the end of the 4th week, the initial procedures were repeated. Histopathologic examination of the tissue samples were carried out by two pathologists. Results: The mean vitamins C and E concentrations in gastric mucosa at the 4th week were higher than those at the beginning (p = .000 and p = .006, respectively). Mean total antioxidant capacity of the body at the beginning and that at the 4th week were similar (p = .689). H. pylori intensity in the antrum at the beginning was higher than that at the 4th week for both pathologists (p = .007 and p = .039). Neutrophilic activity in the antrum at the beginning was higher than that at the 4th week for both pathologists (p = .000 and p = .025). Neutrophilic activity in the corpus at the beginning was higher than that at the 4th week for pathologist 1 (p = .033), and they were similar for pathologist 2 (p = .763). Conclusion: The findings that H. pylori intensity and neutrophilic activity decrease through increasing gastric ascorbic acid and alpha tocopherol concentrations suggest that supplementation with vitamins C and E increases the eradication rates via impairing the microenvironment created by the bacteria and facilitating the diffusion of antibiotics into gastric mucosa.