Vitamin B12 amplifies circadian phase shifts induced by a light pulse in rats

Vitamin B₁₂ (VB₁₂) is a putative modulator of the human circadian clock, improving entrainability to the 24 h light-dark cycle. The present study was intended to elucidate the mechanism of VB₁₂ action in an animal model. In male rats free-running under constant dim illumination, a single light pulse of 50–1000 lux for 20 min given at circadian time (CT) 20 induced a 0.28 to 1.08 h phase advance and at CT 14 induced a 0.54 to 2.10 h phase delay. A 3 h intracerebroventricular (icv) infusion of 30 nmol VB₁₂ starting 2 h prior to a 20 min 200 lux light pulse significantly amplified phase shifts in comparison with saline-treated or untreated controls. The mean phase advance (1.13 h) was 1.8-fold greater than that of saline-infused controls, whereas the mean phase delay (2.28 h) was 2.9-fold greater. These values were comparable to the maximal phase shifts caused by 1000 lux light pulses in untreated rats. Since the same VB₁₂ treatment alone had failed to induce a phase shift in a previous experiment, these results indicate that VB₁₂ strongly enhanced light pulse-induced phase shifts and thus augmented the entrainability of the circadian clock to light.     

崇明小菠菜轮作模式的效益及品质分析

为筛选适合崇明小菠菜（Spinacia oleracea）的特色蔬菜轮作模式,以叶菜为对照,比较了崇明小菠菜与香酥芋、红皮土豆、崇明金瓜、崇明白扁豆、崇明香芋和崇明山药为主要轮作作物的6种轮作模式的经济效益,并分析了轮作对崇明小菠菜产量和品质的影响. 结果表明：崇明金瓜+鲜食玉米+崇明小菠菜（T2）、崇明白扁豆+鲜食玉米+崇明小菠菜（T3）轮作模式的经济效益在轮作2年周期内均最高,增幅均在对照的20%以上. 崇明小菠菜产量增幅在轮作第2年较高,产量最高的轮作模式是崇明红皮土豆+鲜食玉米+崇明小菠菜（T6）. 各轮作模式下,崇明小菠菜的维生素C、可溶性蛋白质及草酸含量均无显著差异;崇明香芋+崇明小菠菜（T1）轮作模式的硝态氮含量显著高于其他模式;可溶性糖含量在T6轮作模式下含量最高. 综合考量经济效益、产量和品质,T2,T3和T6模式可优先应用于崇明小菠菜高效轮作生产.     

荧光分析法测定枸杞中维生素C

本文建立了荧光法快速测定枸杞中维生素C的方法.样品经草酸提取,活性炭氧化后,与邻苯二胺反应,荧光化合物激发波长为343nm,发射波长为425nm.维生素C在3-20mg·L-1浓度范围内测定呈现良好线性关系.     

高锰酸钾分光光度法测定药片中维生素B_1的含量

在0.32mol/L H2SO4溶液中,维生索B1在80℃水浴恒温条件下与KMnO4发生氧化还原反应.采用分光光度法在525 nm处测定KMnO4的吸光度变化值△A.△A值与维生素B1的浓度在4～40μg/mL范围内成良好的线性关系,相关系数R=0.9987,方法检出限为0.8 μg/mL.将该法用于药片中维生素B1含量的测定,相对标准偏差RSD为5.2%,平均回收率为92%,结果满意.     

液相色谱法同时测定乳制品中的胆固醇和维生素A

采用氢氧化钾-无水乙醇溶液直接皂化,石油醚萃取,液相色谱法测定乳制品中的胆固醇和维生素A（VA）,讨论并确定了乳制品中样品皂化、萃取的最佳条件。胆固醇和维生素A的回收率分别为96.56%～106.09%和92.50%～112.00%,RSD分别为2.71%～4.33%和2.98%～4.38%（n=11）。该法具有简便、快速、灵敏、准确等优点。     

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.     

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.     

Thermoperiodically induced diapause in a mite in constant darkness is vitamin A dependent

Summary By rearing the predacious miteAmblyseius potentillae in a daily temperature cycle in constant darkness it could be shown that diapause may be thermoperiodically induced. When the same experiments were performed using diets without vitamin A it appeared that vitamin A is necessary to achieve a state of reproductive diapause in this mite.2 February 1987     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

Summary The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.