发酵中克拉维酸的产生与分解

克拉维酸(CA)是一种有效的β-内酰胺酶抑制剂,与其它β-内酰胺类:头霉素C、青霉素N及脱乙酰氧头孢菌素C等同时由带棒链霉菌产生.CA的生物合成仍未完全阐明.目前已知该途径包含许多中间体和酶.Romero等和Lebrihi等曾对CA形成的调控和生产条件的优化进行了研究.与大多数次级代谢产物一样,CA的生产水平除了取决于温度、pH、氧分压等一般的工艺参数之外,还取决于其它一些调节因素.Aharono-WitZ等曾利用合成和复合培养基研究了碳氮源的性质对带棒链霉菌产生头霉素C的影响,并证明在非限制性快速生长的条件下,     

Overexpression/amplification of HER-2/neu is uncommon in hepatocellular carcinoma

BACKGROUND： Hepatocellular carcinoma （HCC） is one of the most prevalent fatal cancers in the world. Despite advances in early diagnosis and improvements in surgical techniques, the survival of patients with HCC even after resection is poor because of the high incidence of recurrences. Therefore, the identification of prognostic factors may be helpful in the development of new treatment protocols. AIMS： To investigate HER-2/neu status in HCC by immunohistochemistry （IHC） and fluorescence in situ hybridisation （FISH）, and to explore the possibility of using trastuzumab in the treatment of HCC. METH ODS： Eight hundred and sixty eight surgical samples from patients with primary HCC were examined for their HER-2/neu status. IHC for HER-2/neu was performed with the HercepTest kit; FISH analysis was performed with the PathVysion HER-2 DNA probe kit. The correlations between HER-2/neu overexpression and clinicopathological characteristics were analysed statistically. RESULTS： HER-2/neu overexpression was detected in 21 （2.42%） of the 868 primary HCCs. Only one specimen showed HER-2/neu gene amplification by FISH. No significant associations were found between HER-2/neu overexpression and the clinicopathological parameters. CONCLUSIONS： There is a low frequency of HER-2/neu overexpression/amplification in HCC. There appears to be no role for HER-2/neu as a prognostic marker and no benefit of anti-HER-2/neu trastuzumab treatment in patients with HCC.     

Choline: Dietary Requirements and Role in Brain Development

Choline is needed for the maintenance of the structural integrity and signaling functions of cell membranes, for neurotransmission, and for transport of lipids and as a source of methyl groups. Choline can be made de novo in the body, but some individuals must also obtain choline in the diet to prevent deficiency symptoms. A number of environmental and genetic factors influence dietary requirements for choline, and average intakes in the population vary widely. Therefore, certain individuals may be at greater risk of choline deficiency. Choline is critical during fetal development, particularly during the development of the brain, where it can influence neural tube closure and lifelong memory and learning functions.