Head group specificity in the requirement of phosphatidylcholine biosynthesis for very low density lipoprotein secretion from cultured hepatocytes

We have demonstrated that hepatic very low density lipoprotein (VLDL) secretion requires active phosphatidylcholine (PC) synthesis via either the CDP-choline pathway or phosphatidylethanolamine (PE) methylation pathway (Yao, Z., and Vance, D.E. (1988) J. Biol. Chem. 263, 2998-3004). In the present work, the head group specificity of phospholipid synthesis required for lipoprotein secretion was investigated in cultured hepatocytes isolated from choline-deficient rats. When N-monomethylethanolamine (0.1 mM) or N,N-dimethylethanolamine (0.1 mM) was added to the culture medium, the cells synthesized correspondingly phosphatidylmonomethylethanolamine (PMME) or phosphatidyldimethylethanolamine (PDME). However, the synthesis of PDME could correct the impaired VLDL secretion only to a limited extent, whereas the synthesis of PMME inhibited VLDL secretion. Although dimethylethanolamine did not promote VLDL secretion as well as choline, dimethylethanolamine altered the increased triacylglycerol synthesis in the choline-deficient cells as effectively as choline. Supplementation of the culture medium with ethanolamine (0.1 mM) had little effect on cellular PE or PC levels, nor was normal VLDL secretion resumed. However, the amounts of cellular PC and PE were both decreased when the medium was supplemented with N-monomethylethanolamine or N,N-dimethylethanolamine. These results suggest that the choline head group moiety of PC is specifically required for normal VLDL secretion and cannot be replaced with ethanolamine, monomethylethanolamine, or dimethylethanolamine. In addition, the impaired VLDL secretion from the choline-deficient hepatocytes could also be corrected by supplementation of betaine (0.2 mM) and homocysteine (0.2 mM), indicating the utilization of a methyl group from betaine for PC formation via methylation of PE.     

Comparison Study of Bone Defect Healing Effect of Raw and Processed Pyritum in Rats

To evaluate and compare the effect of raw and processed pyritum on tibial defect healing, 32 male Sprague Dawley rats were randomly divided into four groups. After tibial defect, animals were produced and grouped: sham and control group were orally administrated with distilled water (1 mL/100 g), while treatment groups were given aqueous extracts of raw and processed pyritum (1.5 g/kg) for successive 42 days. Radiographic examination showed that bone defect healing effect of the treatment groups was obviously superior compared to that of the control group. Bone mineral density of whole tibia was increased significantly after treating with pyritum. Inductively coupled plasma-optical emission spectrometry showed that the contents of Ca, P, and Mg in callus significantly increased in the treatment groups comparing with the control. Moreover, serological analysis showed that the concentration of serum phosphorus of the treatment groups significantly increased compared with that of the control group. By in vitro study, we have evaluated the effects of drug-containing serum of raw and processed pyritum on osteoblasts. It was manifested that both the drug-containing sera of raw and processed pyritum significantly increased the mRNA levels of alkaline phosphatase and collagen type I. Protein levels of phosphorylated Smad2/3 also increased. The mRNA levels of osteocalcin and transforming growth factor β (TGF-β) type I and II receptors, as well as the protein levels of TGF-β1 in the processed groups, were higher than those in the control. In summary, both raw and processed pyritum-containing sera exhibited positive effects on osteoblasts, which maybe via the TGF-β1/Smad signaling pathway. Notably, the tibia defect healing effect of pyritum was significantly enhanced after processing.     

Recent H3N2 Influenza Virus Clinical Isolates Rapidly Acquire Hemagglutinin or Neuraminidase Mutations When Propagated for Antigenic Analyses

Prior to serological testing, influenza viruses are typically propagated in eggs or cell culture. Recent human H3N2 strains bind to cells with low avidity. Here, we isolated nine primary H3N2 viral isolates from respiratory secretions of children. Upon propagation in vitro, five of these isolates acquired hemagglutinin or neuraminidase mutations that increased virus binding to cell surfaces. These mutations can potentially confound serological assays commonly used to identify antigenically novel influenza viruses.     

The model and algorithm of distributing cooperation profits among operators of urban rail transit under PPP pattern

The financing channels, investors and operators of urban rail transit are becoming more and more diversified, and public private partnership pattern has been increasingly suggested in financing and investment field of urban rail transit in China. The diversification of investors of urban rail transit will no doubt lead to the diversification of operators of urban rail transit network. To legitimately distribute the cooperation profits among operators, a model is developed based on passenger’s path choice behavior by considering travel period, travel time, transfer convenience and the comprehensive proportion of different service types provided by operators. In accordance with the features of urban rail transit network and origin-destination (OD) pairs of transferring among lines of different operators, a scheme of improved rail transit network is proposed. On the basis of the algorithm of breadth-first search and depth-first search, an algorithm of searching effective paths based on backtracking and traversing along the shortest path is established by considering the factor of transfer. Taking the example of Shenzhen’s rail transit network, three typical OD pairs are selected to measure and calculate, compare and analyze by six different conditions. The result shows that travel period, travel time, transfer convenience, and service types provided by operators exert great influence on the distribution of cooperation profits. Therefore, it is advisable to comprehensively consider all of these factors to improve the accuracy of cooperation profits distribution. Moreover, the proposed algorithm can search effective paths efficiently.     

Statures in Han populations of China

<正>Dear Editor,Shortly after initiating the"Physical Anthropological Research on Han Chinese"research project,we applied uniform sampling methods as well as methods and instruments of measurement to obtain a complete set of measurements of physical anthropological indicators among Han populations across China.Among these measurements,body stature was a key indicator.Currently,there should be reliable