儿童维生素A普服的空间影响因素研究

【目的】 了解西部45县3岁以下儿童的维生素A普服情况。从社区方面探讨其空间影响因素,为今后相关工作的开展提供有价值的参考。 【方法】 通过统计描述和比较及秩相关分析法对3岁以下儿童维生素A普服情况及可能的影响指标进行分析。 【结果】 10个省普服率在52.29%(378/719)到81.29%(239/294)之间,45个县普服率在39.58%(57/144)到91.49%(215/235)之间,其中有20个县普服率不到70%。各省、县间的差异均有统计学意义。秩相关分析结果显示仅有“上年底村人口数”、“上年3岁以下儿童数”与3岁以下儿童的维生素A普服率有负相关。 【结论】 西部45县3岁以下儿童的维生素A普服率偏低,尚未发现空间距离对儿童维生素A普服率影响。     

Mechanisms for vitamin A transfer from blood to milk in rhesus monkeys.

In order to study vitamin transport during lactation tritium labeled vitamin A, attached to serum lipoproteins or retinol-binding protein (RBP), was injected intravenously into eight Rhesus monkeys. The turnover rate of vitamin A in plasma and its appearance in milk was quantitatively and qualitatively investigated. The turnover of plasma RBP-retinol, which was somewhat faster in lactating than in non-lactating animals, exceeded that of lipoprotein-vitamin A by a factor of three. Tritium--vitamin A appeared in milk mainly as retinylesters. The fractional rate of transfer was about 60% higher for vitamin bound to RBP than for other forms of plasma vitamin A. Consequently, about 90% of the vitamin A appearing in milk will normally be derived from the retinol-RBP complex. The importance of the lipoprotein-mediated transfer of vitamin A will probably increase during a high intake of the vitamin.     

Vitamin A as "anti-infective" therapy, 1920-1940

In the last fifteen years, a large series of controlled clinical trials showed that vitamin A supplementation reduces morbidity and mortality of children in developing countries. It is less well known that vitamin A underwent two decades of intense clinical investigation prior to World War II. In the 1920s, a theory emerged that vitamin A could be used in "anti-infective" therapy. This idea, largely championed by Edward Mellanby, led to a series of at least 30 trials to determine whether vitamin A--usually supplied in the form of cod-liver oil--could reduce the morbidity and mortality of respiratory disease, measles, puerperal sepsis, and other infections. The early studies generally lacked such innovations known to the modern controlled clinical trial such as randomization, masking, sample size and power calculations, and placebo controls. Results of the early trials were mixed, but the pharmaceutical industry emphasized the positive results in their advertising to the public. With the advent of the sulfa antibiotics for treatment of infections, scientific interest in vitamin A as "anti-infective" therapy waned. Recent controlled clinical trials of vitamin A from the last 15 y follow a tradition of investigation that began largely in the 1920s.     

Morphological changes in the tracheal epithelium of guinea pigs in conditions of "marginal" vitamin A deficiency. A light, scanning- and transmission-electron microscopic study under special breeding conditions appropriate to early vitamin A deficiency.

The aim of the study was to find out the influence of marginal vitamin A deficiency on morphological structures in the tracheobronchial epithelium in guinea pigs. The tracheobronchial epithelium of animals with vitamin A deficiency (n = 15) and control animals (n = 7), kept under optimal laboratory conditions, was evaluated by light and electron microscopy. The cellular ultrastructure was morphometrically analyzed. The height of the respiratory epithelium was slightly increased. The basal cells were arranged in a loose cell band of three to four layers. The quantity of cytofilaments in their cytoplasm was enhanced. Goblet cells were significantly reduced in vitamin A deficiency. There was also a significant decrease in their secretory granules. The number of ciliated cells was almost unchanged. They showed a significant reduction in mitochondria. The kinocilia often contained an atypical structure of the microtubules. Our findings confirm multiple ultrastructural dysplasias in early vitamin A deficiency which may lead to a disturbance of mucociliary clearance.     

维生素A对小鼠致畸作用剂量的影响

目的：观察维生素A的胚胎毒性和致畸作用,以确定VA的致畸剂量。方法：在小鼠胚胎器官形成期,经口给予孕鼠维生素A（VA）1．5g/kg、2．0g/kg、2．7g/kg,于孕后第18天剖腹取仔,观察其活胎外观有无畸形,并对胎仔、骨骼及内脏进行检查。以生理盐水作为对照组。结果：高剂量组交配成功率明显下降,第18天处死前孕鼠体重无明显变化,但中剂量组母鼠增重明显减少（P＜0．05）,高剂量组母鼠增重高于中剂量组,低于阴性对照组。仔鼠统计指标中,吸收胎率、死胎率显著高于阴 对照组（P＜0．05）。各剂量组同吸收胎率也呈显著变化（P＜0．05）。VA3个剂量组的活胎外观畸形率依次增高,且高剂量组与阴性对照组比有显著性（P＜0．05）,各组的骨骼畸形率均显著高于阴性对照组（P＜0．05）,并且各组间也有显著变化（P＜0．05）。内脏检查末见畸形。结论：VA作为孕鼠致畸实验的阳性对照品,以经口给予2mg为宜。     

重庆市中小学生维生素A营养状况及影响因素分析

目的 了解重庆市6～17岁中小学生维生素A营养状况,并分析维生素A缺乏的影响因素,为后续研究和制定营养改善措施提供科学依据.方法 于2016-2017年,通过多阶段分层与人口成比例整群随机抽样方法在重庆市选择3个农村点和3个城市点,抽取1 508名6～17岁儿童青少年,开展问卷调查和实验室检测,采用SPSS 25.0进...     

Changes in hepatic parenchymal and nonparenchymal cell vitamin A content during vitamin A depletion in the rat

Levels of total, unesterified and esterified retinol were determined in liver, liver parenchymal cells (PC) and liver nonparenchymal cells (NPC) during vitamin A depletion in rats. Liver vitamin A levels decreased from 113 to 4 micrograms over a 97-d experimental period; plasma retinol concentrations did not change significantly during this time. Initially, greater than 90% of hepatic vitamin A was in the esterified form and most (93%) was localized in NPC. During vitamin A depletion, there were significant declines in retinyl ester content of both PC and NPC, but unesterified retinol levels were not significantly affected. Plasma retinol concentrations were significantly correlated with unesterified retinol mass in PC and NPC, but not with retinyl ester mass. Although 94% of the liver's negative vitamin A balance was due to changes in NPC retinyl ester levels, the fractional rate of retinyl ester loss from PC and NPC was almost identical. Since unesterified retinol levels in plasma, PC and NPC appeared to be conserved even when liver retinyl ester stores were virtually depleted, and since the retinol utilization rate was apparently not decreasing during this stage of vitamin A depletion, these data support the hypotheses that homeostatic mechanisms controlling the three pools of unesterified retinol are linked, and that vitamin A utilization rate is maintained as long as unesterified retinol levels in plasma, PC and NPC are normal.     

Vitamin A deficiency disorders: international efforts to control a preventable "pox"

Visual symptoms (night blindness) of vitamin A deficiency (VAD) were among the earliest diet-related deficiencies documented. Knowledge of vitamin A chemistry, metabolism and deficiency consequences accrued rapidly during the first eight decades of the 20th century. A series of disorders were described in animals, including impaired growth, reproduction, epithelial integrity, and disease resistance that were relieved by consumption of both animal and plant sources of the vitamin. Identification of the intestinal beta-carotene cleavage enzyme in the laboratory of James Allen Olson was seminal to understanding the mechanism for formation of vitamin A from ingested carotenoids. WHO's 1990 estimate of about 40 million children annually with clinical eye signs of VAD was revised upward to 140-250 million at risk of vitamin A deficiency disorders (VADD) when epidemiological and clinical trials demonstrated morbidity and mortality risk even in the absence of ocular signs. Alternative methods for VAD status assessment and more reliable analytical techniques were developed, several in Dr. Olson's laboratory. The last decade has seen global progress in VADD control by expanding distribution of medicinal supplements, fortification of foods and dietary diversification through horticulture and education programs. Experience shows that achievements gained through narrowly focused interventions are fragile and vulnerable to national political and economic instability. Contextually relevant, community-centered strategies that improve household food and nutrition security and self-reliance are critical to sustaining international efforts to control the VADD "pox."     

对4个农村贫困县5岁以下儿童定期普服维生素A预防呼吸道感染和腹泻效果的前瞻性队列研究

目的:探讨定期普服维生素A对儿童感染性疾病患病率的影响。方法:分层抽样选取云南省4个县3669名5岁以下儿童,调查其两周患病情况,测量身高(身长)和体重,采用SPSS13.0软件进行统计分析。结果:①患病率及相对危险度(RR):支气管炎患儿服维生素A后患病率1.1%,RR=1.5,χ2=5.5,其他各疾病患病率服维生素A组明显低于对照组(服药前),RR均大于1,差异均有统计学意义。②归因危险度百分比(AR%):服维生素A后比服维生素A前各患病率降低19.2%～81.4%;人群归因危险度百分比(PAR%)为11.1%～69.2%。③平行对照:呼吸道、消化道感染及营养不良等患病率只有急性呼吸道感染和急性腹泻的相对危险度,对照组高于试验组;服维生素A双剂量优于单剂量。结论:普服维生素A对呼吸道和肠道感染有保护效应,双剂量效果更佳。     

Effect of simultaneous supplementation of vitamin A and iron on diarrheal and respiratory tract infection in preschool children in Chengdu City,China

ObjectiveThe goal of this study was to investigate whether vitamin A combined with iron supplementation for preschool children resulted in improved changes in children's infectious morbidity.MethodIn this randomized placebo-controlled and blinded field intervention trial, totally 445 preschoolers, ages 3 to 6 y old, were randomly selected. All children were randomly divided into four groups: vitamin A supplement-only group (group I), iron supplement-only group (group II), vitamin A and iron supplement group (group III), and no vitamin A and ferrous sulfate as placebo-control (group IV) for 6 mo. The morbidity of diarrhea and respiratory infections, were collected during supplementation.ResultsThere was evidence of the lowest incidence rate of respiratory-related illnesses and fewest symptoms of runny nose, cough, and fever for children in group III compared with children in groups I, II and IV (P < 0.05). Moreover, despite the undistinguished incidence rate of vomiting, nausea, and stomach pain, the rate of diarrhea-related illness was significantly lower for children in group III than for those in the other three groups.ConclusionThe beneficial affects on infectious morbidity over 6 mo, highlight the potential of vitamin A plus an iron supplement for preschool-aged children.     

Multivitamin-mineral supplementation prevents lipid peroxidation during "the Marathon des Sables"

OBJECTIVE: We investigated the effect of a moderate mutivitamin and mineral supplementation containing mainly vitamin C (150.0 mg.day(-1)), vitamin E (24.0 mg.day(-1)) and beta-carotene (4.8 mg.day(-1)) prior to and during an extreme running competition -the Marathon des Sables (MDS)- that consisted of six long races in the desert. METHODS: Seventeen athletes participated in our double blind, placebo-controlled study. Blood samples were collected prior to the supplementation i.e. three weeks before the competition (D-21), two days prior to the MDS (D-2), after the third race (D3) and at the end of the competition (D7). Erythrocyte antioxidant enzyme activity (glutathione peroxidase (GPx), superoxide dismutase (SOD)), erythrocyte glutathione level (GSH), plasma non-enzymatic antioxidant status (uric acid, vitamin C, alpha-tocopherol, retinol, beta-carotene), markers of plasma lipid peroxidation (thiobarbituric reactive substances (TBARS)), reactive carbonyl derivatives (RCD) and membrane damage (creatine kinase and lactate dehydrogenase activities) were measured. RESULTS: In both groups, GSH levels, uric acid levels and membrane damage significantly increased during the competition while SOD activity significantly decreased. In Supplemented group, plasma alpha-tocopherol, beta-carotene and retinol levels significantly increased after three weeks of supplementing. In contrast to Placebo group, alpha-tocopherol, vitamin C and retinol levels were significantly affected by the competition in Supplemented group. Moreover, no increase in TBARS was observed in Supplemented group during the competition, whereas TBARS significantly increased at D3 in the placebo group. CONCLUSION: The moderate multivitamin-mineral supplementation prevented the transient increase in TBARS levels during this extreme competition.     

大理州孕早期女性血清维生素A、E水平调查

目的了解大理州孕妇妊娠早期血清维生素A、E水平,评价妊娠期维生素的营养状况,指导孕妇妊娠期合理补充维生素。方法收集2017年1月-2018年4月大理州孕妇妊娠早期血清样本共计2861份,采用高效液相色谱法定量测定血清维生素A、E的浓度。结果孕妇妊娠早期血清维生素A检测值为(0.44±0.10)ng/ml,血清维生素E为(14.55±4.09)ng/ml。与参考值比较,血清维生素A总体异常率2.48%,缺乏率2.06%,过量率0.42%;维生素E总体异常率3.32%,全部为过量异常,本研究中未检测到维生素E缺乏的情况。结论大理州孕妇妊娠早期血清维生素A、E水平95%以上均在正常参考范围内,维生素A异常以缺乏为主,维生素E以过量为主。重视孕期维生素A、E水平监测,合理正确补充,对保障母婴安全有重要意义。     

云南省600例0~5岁儿童维生素A缺乏调查

目的:了解云南省城乡0~5岁儿童维生素A营养状况及影响因素。方法:省、地、县随机整群抽取600例儿童,采用微量荧光光度法检测VitA含量。结果:VitA缺乏发生率16·17%,地、县明显高于省会城市;0岁儿童明显高于其他年龄组;腹泻儿童明显高于正常儿童;VitA缺乏的影响因素:近1周内进食鸡蛋、奶类制品、鱼虾类、肝类、黄绿色蔬菜、鱼肝油等食物有利于维生素A的吸收,急性呼吸道感染、发烧与维生素A缺乏发生率差异不明显。结论:维生素A缺乏发生率城市明显低于农村地、县两级,说明维生素A缺乏防治工作重点在农村,特别是0岁儿童,防治的主要措施是采取合理膳食,均衡营养,控制腹泻流行。     

2015年中国农村老年人维生素A营养状况及影响因素

目的 了解中国农村老年人维生素A水平及影响因素.方法 采用随机抽样方法选取2015年中国成人慢性病与营养监测生物样本库的农村老年人血清样本,共纳入3134名60岁以上农村老年人作为研究对象.采用问卷调查收集研究对象基本信息,利用高效液相色谱法分析仪测定调查对象血清中维生素A含量,依据WHO推荐的标准判定人群维生素A营养...     

The "ideal" daily vitamin A intake.

This approach suggests that the healthier the sample, the greater the daily vitamin A intake. Under the conditions of this experiment, approximately 33,000 I.U. of vitamin A may be designated as the "ideal" daily allowance. This is almost seven times the RDA of 5000 I.U. for the adult male and eight times higher than the 4000 I.U. RDA for adult females. It is recognized that the "ideal" is nonexistent as a theoretic end-point since there is biochemical individuality and because the art of measuring leaves much to be desired. Nonetheless, the technique utilized here provides a mechanism and a goal not previously considered.     

2017—2018年淮安地区孕妇维生素A、维生素E水平及其影响因素

目的分析不同孕期血清维生素A、维生素E水平及其影响因素。方法选取2017年1月-2018年5月在淮安市妇幼保健院常规产检的孕早、中、晚期的共2824例孕妇,采用高效液相色谱法定量测定血清维生素A及维生素E的浓度。采用多元线性回归分析影响血清维生素A、维生素E水平的相关因素。结果淮安地区孕妇血清维生素A水平为(0.39±0.08) mg/L,总体异常率为12.3%;血清维生素E水平为(13.28±4.67) mg/L,总体异常率为3.7%。多元线性回归分析发现年龄、子痫前期与血清维生素A呈正相关;年龄、食欲、子痫前期与血清维生素E呈正相关。结论淮安地区孕妇血清维生素A异常以缺乏为主,血清维生素E异常以过量为主。     

6月龄婴儿维生素A缺乏症的影响因素研究

目的调查深圳市龙岗区6月龄婴儿维生素A水平,分析维生素A缺乏症的影响因素,为维生素A缺乏症的防控提供依据。方法以2019年1—12月在龙岗区妇幼保健院儿保门诊接受健康体检的1638例6月龄婴儿为研究对象,检测婴儿血清维生素A水平,并分析维生素A缺乏症可能的影响因素。1638例婴儿根据喂养方式分为母乳喂养组(n=1005)、混合喂养组(n=228)和配方奶喂养组(n=405);根据维生素AD补充情况分为持续补充组(n=183)、交替补充组(n=420)及单独补充组(n=1035)。结果6月龄婴儿血清维生素A平均水平为(0.30±0.07)mg/L。维生素A缺乏的婴儿882例(53.84%),维生素A平均水平为(0.24±0.03)mg/L,其中边缘型维生素A缺乏795例(48.53%),亚临床型维生素A缺乏87例(5.31%);维生素A正常的婴儿756例,维生素A平均水平为(0.36±0.06)mg/L。持续补充组维生素A缺乏症检出率明显低于交替补充组及单独补充组,差异均有统计学意义(χ²值分别为26.818、36.050,均P<0.05)。母乳喂养组及混合喂养组维生素A缺乏症检出率均高于配方奶喂养组,差异均有统计学意义(χ²值分别为113.482、47.534,均P<0.05)。早产的婴儿维生素A缺乏症检出率高于足月的(χ²=16.957,P<0.05)。多因素二分类Logistic回归分析显示母乳喂养(OR=4.196)、混合喂养(OR=3.466)增加了婴儿维生素A缺乏症的发生风险(均P<0.05);持续补充维生素AD(OR=0.361)、足月(OR=0.326)、6月龄时未患营养不良(OR=0.257)、6月龄内未患呼吸道感染(OR=0.675)降低了维生素A缺乏症的发生风险(均P<0.05)。结论深圳市龙岗区6月龄婴儿维生素A缺乏症检出率较高,母乳喂养儿、混合喂养儿及早产儿出生后6月龄内应及时、合理地补充推荐摄入量的维生素AD。     

Was the "Anti-Infective" Vitamin Misnamed?

Meta-analyses on 6 of 12 studies of the effect of improvement of the vitamin A status of deficient children living in poverty and social and biological deprivation conclude that mortality reduction can be expected. The demonstrated effects on incidence, prevalence and severity of specific morbidities under these conditions have been variable.     

维生素A、E辅助药物治疗儿童反复呼吸道感染的疗效及免疫状态分析

目的分析维生素A、E辅助药物治疗儿童反复呼吸道感染的疗效及免疫状态。方法选择2016年3月-2018年1月就诊的100例儿童反复呼吸道感染患儿,根据随机双盲法进行分组。对照组50例,单用匹多莫德治疗;研究组50例,在匹多莫德治疗基础上加用维生素A、E辅助治疗,均治疗3周。比较两组临床疗效、治疗相关指标、不良反应,并观察治疗前、治疗3周后T淋巴细胞亚群、免疫球蛋白及维生素A、E水平变化。结果研究组治疗总有效率比对照组高(P<0. 05)。研究组治愈时间、感染持续时间比对照组短,感染次数比对照组低(均P<0. 05)。治疗3周后,研究组CD3^+T淋巴细胞亚群水平比对照组高,CD4^+T淋巴细胞亚群、CD8^+T淋巴细胞亚群水平比对照组低(均P <0. 05),IgA、IgG、IgM水平比对照组高(均P <0. 05),维生素A、E水平比对照组高(均P<0. 05)。两组治疗前后T淋巴细胞亚群、免疫球蛋白水平及维生素A、E水平比较差异均有统计学意义(均P<0. 05)。两组不良反应发生率比较差异无统计学意义(P>0. 05)。结论维生素A、E辅助药物治疗儿童反复呼吸道感染疗效确切,可降低患儿疾病复发次数,缩短病程,调节细胞及体液免疫功能,加强机体抗病能力,且安全性较高,利于获得良好预后。