Defect in vitamin B12 release from lysosomes: newly described inborn error of vitamin B12 metabolism

Cultured diploid fibroblasts from a patient with a previously undescribed inborn error of cobalamin metabolism accumulate unmetabolized, nonprotein-bound vitamin B12 in lysosomes. These cells are able to endocytose the transcobalamin II-B12 complex and to release B12 from transcobalamin II. The freed vitamin B12 is not released from lysosomes into the cytoplasm of the cell. This suggests that there is a specific lysosomal transport mechanism for vitamin B12 in the human.     

Methylmalonate excretion in vitamin B12 deficiency

Urinary methylmalonate excretion is increased in rats with an insufficiency of vitamin B(12). Excretion of methylmalonate is not affected by folic acid, vitamin E, or selenium, but is markedly decreased by small amounts of vitamin B(12) added to the diet.     

Methyl mercury and inorganic mercury collection by a selective chelating resin

A commercially available chelating resin selectively and quantitatively collects methyl mercuric and inorganic mercuric forms of mercury to the exclusion of all other metals studied, except the noble metals. Both forms of mercury can be collected from pH 1 to 9. Collected mercury is readily eluted with a slightly acid, 5 percent solution of thiourea, and the resin can be reused for many cycles. Selectivity, pH effects, capacity, and elution characteristics of the resin are described. A resin-loaded paper composed of 50 percent resin and 50 percent cellulose shows properties similar to those of the loose resin.     

UASB-A/O工艺处理淀粉、淀粉制糖、VB12混合废水

采用UASB—A/O工艺处理淀粉、淀粉制糖、VB12混合废水的实际运行结果表明,系统运行稳定,对COD、NH3-N的去除率分别为98.2%和92%,出水水质达到了《城镇污水处理厂污染物排放标准》(GB18918-2002)中的二级标准值。     

Methylmalonic aciduria: metabolic block localization and vitamin B 12 dependency

Methylmalonic aciduria is an inborn error of metabolism characterized by neonatal or infantile ketoacidosis. Leukocytes isolated from the peripheral blood of a 1-year-old child with this disorder converted negligible quantities of propionate-3-C(14) to carbon dioxide, but oxidized succinate-1,4-C(14) normally, an indication of a block in the conversion of propionate to succinate. Parenteral administration of vitamin B(18) resulted in a reduction in methylmalonic acid excretion and an increase in propionate oxidation by leukocytes in vitro. The results suggest a mutation of methylmalonyl-CoA isomerase, a vitamin B(12), dependent enzyme which converts methylmalonyl-CoA to succinyl-CoA, and provide the first demonstration of vitamin B(12) "dependency" in man.     

维生素B12添加剂测定方法之比较分析

维生素B12粉剂是饲料生产中常用的维生素B12添加剂.本品是以维生素B12为原料,加入玉米淀粉或碳酸氢钙等稀释剂制成的粉剂,常见的3种产品分别含有1%、5%、10%维生素B12.维生素B12又称氰钴胺,因其含有元素钴,其粉剂为浅红色至棕色粉末,市售1%粉剂为浅红色,因其价格较高,该原料常有掺假现象.     

1alpha-Hydroxyvitamin D2: a potent synthetic analog of vitamin D2

A hydroxy analog of vitamin D(2), 1alpha-hydroxyvitamin D(2), has been synthesized and tested for biological activity. This vitamin derivative is active in stimulating intestinal calcium transport and bone calcium mobilization in the rat and exhibits antirachitic activity. Its biopotency is comparable to that of the corresponding vitamin D(3) analog, 1alpha-hydroxyvitamin D(3).     

烟酸铜、烟酸锌对V_A、V_(B_2)、V_(B_6)稳定性的影响

制备铜、锌螯合盐烟酸铜、烟酸锌,并将烟酸铜、烟酸锌、CuSO4、ZnSO4、蛋氨酸铜及蛋氨酸锌分别与VA、VB2、VB6直接混合,比较它们各自对维生素稳定性的影响.结果表明,它们对维生素的稳定性影响的大小顺序依次是硫酸盐、氨基酸盐、烟酸盐.可见烟酸盐对维生素的稳定性影响最小,可作为新型微量元素添加剂与维生素混合制成预混合饲料.     

藻源溶解性有机质对汞甲基化的影响

  目的  探究藻源溶解性有机质(DOM)各亚组分在不同腐解时间、不同汞(Hg2+)质量浓度下对水体中汞甲基化的影响。  方法  应用树脂串联技术分离藻体DOM的6种亚组分,利用室内培养方式进行Hg2+的甲基化试验。  结果  藻类DOM主要由羟基、烃基和芳环C=C等官能团组成;未经腐解的DOM各亚组分中,疏水性有机组分对汞甲基化的影响高于亲水性有机组分;随腐解时间延长,DOM官能团逐渐减少,疏水性有机组分对汞甲基化的影响表现为先降低后升高;亲水性有机组分抑制汞甲基化。  结论  DOM相对含量的升高抑制了汞的甲基化,DOM降解后,释放出来的Hg2+被微生物重新利用,甲基化程度加剧。图3参24     

维生素B1和B12对米氏凯伦藻增殖的影响

[目的]研究维生素B1、B12在米氏凯伦藻有毒赤潮爆发增殖过程中的作用。[方法]设置7个不同浓度的维生素B1与B12的K培养基培养米氏凯伦藻,通过定期浮游计数框计数与活体叶绿素荧光值的测定,研究不同浓度维生素B1、B12下,米氏凯伦藻细胞密度与叶绿素荧光值的变化情况。[结果]在维生素B1浓度低于0.312 5×10-5g/L时,对米氏凯伦藻细胞密度与单位细胞叶绿素荧光值有显著影响（P〈0.05）;维生素B12浓度变化对米氏凯伦藻细胞密度与单位细胞叶绿素荧光值影响不显著（P〉0.05）。[结论]维生素B1对米氏凯伦藻细胞增殖有显著影响,维生素B12对米氏凯伦藻种群增殖的影响不显著。     

Vitamin B12 requirement of a marine blue-green alga

A species of Synechocystis isolated from a marine mud has an absolute requirement for vitamin B(12). Analogues of B(12), including cobinamide and alpha-(adenyl) cobamide cyanide, satisfactorily substitute for vitamin B(12). Methionine alone or in combination with other compounds supports only a low level of growth.