铅锌镉联合染毒及营养干预对大鼠血液系统的影响研究

目的：了解铅锌镉联合染毒对大鼠血液系统的影响及营养干预对其损伤的修复作用。方法：选择SPF级初断乳Wistar大鼠72只,随机分为对照组、染毒组和干预组,分别采用生理盐水、铅锌镉联合染毒液及染毒后以营养干预液灌胃28天和56天之后,检测其血液系统中五元素和血细胞的指标。结果：染毒组较对照组大鼠血铜、血锌含量高,血钙含量低于对照组,差异均有统计学意义（P〈0．05）;染毒组血铜含量高于干预组,血钙含量低于干预组,差异均有统计学意义（P〈0．05）;干预组红细胞（RBC）计数、血红蛋白（Hb）、血细胞比容（HCT）均高于染毒组,差异均有统计学意义（P〈0．05）;对照组白细胞（WBC）计数高于染毒组、干预组,差异均有统计学意义（P〈0．05）。结论：铅镉对大鼠血铜、血钙、血锌水平有影响;综合营养干预对重金属元素造成的血液系统损伤有明显的拮抗作用,对血液系统有一定的保护及修复作用。     

Assembly of colicin genes from a few DNA fragments. Nucleotide sequence of colicin D

The nucleotide sequence of a 2.4 kb Dral-EcoRV fragment of pColD-CA23 DNA was determined. The segment of DNA contained the colicin D structural gene (cda) and the colicin D immunity gene (cdi). From the nucleotide sequence it was deduced that colicin D had a molecular weight of 74683D and that the immunity protein had a molecular weight of 10057D. The amino-terminal portion of colicin D was found to be 96% homologous with the same region of colicin B. Both colicins share the same cell-surface receptor, FepA, and require the TonB protein for uptake. A putative TonB box pentapeptide sequence was identified in the amino terminus of the colicin D protein sequence. Since colicin D inhibits protein synthesis, it was unexpected that no homology was found between the carboxy-terminal part of this colicin and that of the protein synthesis inhibiting colicin E3 and cloacin DF13. This could indicate that colicin D does not function in the same manner as the latter two bacteriocins. The observed homology with colicin B supports the domain structure concept of colicin organization. The structural organization of the colicin operon is discussed. The extensive amino-terminal homology between colicins D and B, and the strong carboxy-terminal homology between colicins B, A, and N suggest an evolutionary assembly of colicin genes from a few DNA fragments which encode the functional domains responsible for colicin activity and uptake.     

Idiopathic megaesophagus in a rat (Rattus norvegicus)

Necropsy and histopathologic examination of a rat (Rattus norvegicus) revealed megaesophagus and gangrenous bronchopneumonia. The esophageal dilitation, mural atrophy with persistence of neural structures, regurgitation and bronchopneumonia seen in this case were similar to findings in other animals with megaesophagus.     

Derivation and characterisation of hESC lines from supernumerary embryos, experience from Odense, Denmark

The derivation and characterisation of human embryonic stem cells provides a source of pluripotent stem cells with potential for clinical applications. Utilising locally sourced embryos from two IVF clinics, we derived and characterised five new cell lines for use in a non-clinical setting. Analysis of clinical data showed that the majority of embryos (94.5%) failed to reach the blastocyst stage of development and of all embryos, regardless of developmental status, 248 embryos were needed to create one stem cell line. From the number of embryos (69) which developed to the blastocyst stage 8.7% developed into cell lines. Using outgrowth of the whole blastocyst, we derived five new, unreported cell lines in Odense, Denmark between 2005 and 2006. Characterisation was carried out using RT-PCR, staining, karyotyping, EB formation and teratoma formation. The KMEB hESC lines will, in the future, be made available through the UK Stem Cell Bank (http://www.ukstemcellbank.org.uk/).     

Soluble rat adipocyte phosphatidate phosphatase activity: characterization and effects of fasting and various lipids.

Phosphatidate phosphatase (phosphatidate phosphohydrolase, EC 3.1.3.4) was present at very high specific activity in the soluble fraction of isolated rat adipocytes. Using phosphatidate in aqueous dispersion 90% of its hydrolysis depended on the presence of Mg2+. Mg2+ appeared to almost saturate the enzyme at 20-40 mM with no indication of an optimum. The substrate concentration was optimum at 1.2 mM and the pH at 6.8. Initial rates were linear for only 4-5 min at optimum conditions. Increasing inhibition occurred at high phosphatidate concentrations. At optimum conditions acid or alkaline phosphatase activity was not measurable. The Mg2+-dependent activity was enhanced by 3-sn-phophatidylcholine and inhibited by albumin, 3-sn-phosphatidyletanolamine, 3-sn-phosphatidylinositol, diacylglycerol, oleoyl-CoA, and oleate. Oleoyl-CoA was the most potent "effector". Fasting for 24, 48 and 72 h decreased the activity both relative to protein and to DNA. The activity thus decreased to about one-third of that of the fed rat during 72 h of fasting. The effects of Mg2+, various lipids, and fasting may indicate that some form of control of glyceride synthesis can be exerted through the soluble phosphatidate phosphatase.     

Purification and properties of 2,3-bisphosphoglycerate phosphatase-mutase from erythrocytes of day-old chicks.

After tryptic digestion of intact Staphylococcus aureus the residual portion of protein A that was still bound to the cell wall was cleaved off with lysostaphin. From the two digests Fc-binding fragments were isolated and the following characteristics observed. (a) There are four Fc-binding, highly homologous regions, each consisting of 58--62 amino acid residues. (b) These regions are consecutively arranged from the N-terminal part of the protein. (c) The residual C-terminal part, approximately 150-residues long, differs to a great extent with respect to primary and secondary structures from the four active regions. Furthermore, it is suggested that the protein is bound to the bacterial cell wall structure through this C-terminal part.     

Supramolecular structures of peptide assemblies in membranes by neutron off-plane scattering: method of analysis

In a previous paper (Yang et al., Biophys. J. 75:641-645, 1998), we showed a simple, efficient method of recording the diffraction patterns of supramolecular peptide assemblies in membranes where the samples were prepared in the form of oriented multilayers. Here we develop a method of analysis based on the diffraction theory of two-dimensional liquids. Gramicidin was used as a prototype model because its pore structure in membrane in known. At full hydration, the diffraction patterns of alamethicin and magainin are similar to gramicidin except in the scale of q (the momentum transfer of scattering), clearly indicating that both alamethicin and magainin form pores in membranes but of different sizes. When the hydration of the multilayer samples was decreased while the bilayers were still fluid, the in-plane positions of the membrane pores became correlated from one bilayer to the next. We believe that this is a new manifestation of the hydration force. The effect is most prominent in magainin patterns, which are used to demonstrate the method of analysis. When magainin samples were further dehydrated or cooled, the liquid-like diffraction turned into crystal-like patterns. This discovery points to the possibility of investigating the supramolecular structures with high-order diffraction.