烟酸缺乏症的研究进展

烟酸缺乏症又名陪拉格,是一种营养缺乏性疾病,同时又是光敏性疾病。本文从流行病学、病因及发病机理、临床特征、实验室检查、诊断及鉴别诊断和治疗等方面对烟酸缺乏症的研究进展作一综述。     

The biochemical pathways of central nervous system neural degeneration in niacin deficiency

Neural degeneration is a very complicated process. In spite of all the advancements in the molecular chemistry, there are many unknown aspects of the phenomena of neurodegeneration which need to be put together. It is a common sequela of the conditions of niacin deficiency. Neural degeneration in Pellagra manifests as chromatolysis mainly in pyramidal followed by other neurons and glial cells. However, there is a gross lack of understanding of biochemi- cal mechanisms of neurodegeneration in niacin deficiency states. Because of the necessity of niacin or its amide derivative NAD in a number of biochemical pathways, it is understandable that several of these pathways may be involved in the common outcome of neural degener- ation. Here, we highlight five pathways that could be involved in the neuraldegeneration for which evidence has accumulated through several studies. These pathways are： 1） the trypto- phan-kyneurenic acid pathway, 2） the mitochondrial ATP generation related pathways, 3） the poly （ADP-ibose） polymerase （PARP） pathway, 4） the BDNF-TRKB Axis abnormalities, 5） the genetic influences of niacin deficiency.     

Elevated K-ras activity with cholestyramine and lovastatin, but not konjac mannan or niacin in lung--importance of mouse strain

Our previous work established that hypocholesterolemic agents altered K-ras intracellular localization in lung. Here, we examined K-ras activity to define further its potential importance in lung carcinogenesis. K-ras activity in lungs from male A/J, Swiss and C57BL/6 mice was examined. For 3 weeks, mice consumed either 2 or 4% cholestyramine (CS), 1% niacin, 5% konjac mannan (KM), or were injected with lovastatin 25mg/kg three or five times weekly (Lov-3X and Lov-5X). A pair-fed (PF) group was fed the same quantity of diet consumed by the Lov-5X mice to control for lower body weights in Lov-5X mice. After 3 weeks, serum cholesterol was assayed with a commercial kit. Activated K-ras protein from lung was affinity precipitated with a Raf-1 ras binding domain-glutathione-S-transferase fusion protein bound to glutathione-agarose beads, followed by Western blotting, K-ras antibody treatment, and chemiluminescent detection. Only KM reduced serum cholesterol (in two of three mouse strains). In C56BL/6 mice treated with Lov-3X, lung K-ras activity increased 1.8-fold versus control (p=0.009). In normal lung with wild-type K-ras, this would be expected to be associated with maintenance of differentiation. In A/J mice fed 4% CS, K-ras activity increased 2.1-fold (p=0.02), which might be responsible for the reported enhancement of carcinogenesis in carcinogen-treated rats fed CS. KM feeding and PF treatment had no significant effects on K-ras activity. These data are consistent with the concept that K-ras in lung has an oncogenic function when mutated, but may act as a tumor suppressor when wild-type.     

复方烟酸辛伐他汀双层片体外释放度的研究

目的 考察复方烟酸辛伐他汀双层片中缓释层烟酸与速释层辛伐他汀的体外释放度。方法 以国内上市的烟酸缓释片（商品名本悦）作为对照片,用UV法比较了本院自制的复方烟酸辛伐他汀双层片缓释层中烟酸在水、0.1mol/L盐酸及pH 6.8磷酸盐缓冲液三种介质中的释放情况,同时以含0.5%十二烷基硫酸钠（SLS）的0.01?mol/L磷酸盐缓冲液（pH 7.0）为溶出介质,采用HPLC法测定了速释层中辛伐他汀的释放情况。结果 自制复方烟酸辛伐他汀双层片中烟酸在3、9和16h的累积百分释放度在10%～30%、40%～60%和75%以上,符合规定。复方烟酸辛伐他汀双层自制片和对照片中烟酸的释放曲线均符合Higuchi方程,相关系数大于0.99,相似因子f2值在规定的50～100之内。速释层中辛伐他汀在45min内溶出80％以上。结论 自制复方烟酸辛伐他汀双层片与对照片中烟酸的释放性能相似,辛伐他汀溶出度亦符合要求。     

A study on degradation kinetics of niacin in potato (Solanum tuberosum L.)

The kinetics of niacin degradation in potato (Solanum tuberosum L.) as well as in pure niacin solutions at initial concentrations present in potato has been studied over a temperature range of 50–120 °C (isothermal process). Niacin degradation followed first-order kinetics, where the rate constant increased with an increase in the temperature. The temperature dependence of degradation was adequately modeled by the Arrhenius equation. The degradation kinetics of niacin in normal open pan cooking, pressure-cooking and a newly developed and patented fuel-efficient “EcoCooker” has also been studied (non-isothermal process). A mathematical model has been developed using the isothermal kinetic parameters obtained to predict the losses of niacin from the time–temperature data of the non-isothermal heating/cooking process. The results obtained indicate a niacin degradation of a similar magnitude in all three modes of cooking used in the study.