Supercritical fluid extraction and reversed-phase liquid chromatography methods for vitamin A and beta-carotene heterogeneous distribution of vitamin A in the liver

In the present study, we have performed chemical investigations of the stem cell walls during internode maturation in order to study the growth dynamics of alfalfa and the deposition of the main cell wall components (polysaccharides and lignins). Internode cell walls were analysed by chemical fractionation using a mild delignification step aiming at sequential removal of polysaccharides and lignins. Delignification facilitated the subsequent removal of the xylose-rich polysaccharides by NaOH extraction as previously shown. This trend was more pronounced in the case of older internodes which have a larger proportion of secondary tissues containing syringyl type lignins in contrast to younger ones which are mainly composed of primary tissues containing guaiacyl type lignins and pectin rich cell walls.     

The nitric oxide donor sodium nitroprusside protects against hepatic microcirculatory dysfunction in early endotoxaemia

OBJECTIVE: Endotoxin rapidly inhibits the activity of the constitutive endothelial nitric oxide synthase (ecNOS); this precedes the production of NO from inducible NOS (iNOS). This leaves a period in early endotoxaemia with a supposed scarcity of NO. The present study was conducted to examine the effects of external supplementation of NO on liver microcirculation and function. MATERIAL: 13 male Sprague Dawley rats. INTERVENTIONS: The rats underwent laparotomy, and the left liver lobe was exteriorised. All animals were given a bolus dose of endotoxin (LPS) 5 mg/kg intraportally. One group (n = 6) had a continuous infusion of sodium nitroprusside (SNP) 1.4 microg/kg per min started concurrently, the other group (n = 7) was treated with normal saline. The study was terminated after 3 h LPS. MEASUREMENTS AND RESULTS: Intravital microscopy was performed at baseline, at 2 h and 3 h LPS. Hepatic function was assessed by arterial ketone body ratio, acid base values, and bile flow. At baseline 1% of the sinusoids were without perfusion. After 2 h LPS this figure had risen to 9.8+/-1.5% in the SNP group versus 16.9+/-1.4% in the controls (p < 0.05 vs controls). The corresponding values after 3 h LPS were 13.5+/-1.5 versus 19.3+/-1.5% (p < 0.05 vs controls). The leukocyte count in sinusoids and venules had a similar development. Functional parameters were all slightly better preserved in the SNP group, but with no individual significance versus controls. CONCLUSIONS: Infusion of the NO donor SNP in early endotoxaemia attenuates the detrimental effects of LPS on liver microcirculation, most probably by alleviating a relative deficit of NO at the microcirculatory level.     

开口薄壁箱型拱桥转体施工模拟分析

运用有限元软件ANSYS对湖北省恩施州金鸡口二号桥进行转体施工的数值模拟,计算出转动体系的重心位置、脱架后拱肋的变形与应力,背墙的变形与应力均满足规范要求,论证了该桥施工方案的可行性和合理性,为顺利安全地进行转体施工提供了保障,并为同类桥型的转体施工提供有用的借鉴。     

FSBA modifies both alpha- and beta-subunits of F1 specifically and can be bound together with AXP at the same alpha-subunit

Binding of 1 mole 5'-fluorosulfonylbenzoyladenosine (FSBA) per mol F1 induces about 50% inhibition of ATPase activity and 80% inhibition of ITPase activity. The binding of additional ligand results in a further inhibition of both activities. Maximally 5 mol/mol F1, causing complete inhibition of activity, can be bound. Using radioactive FSBA more label is found on alpha-subunits than on beta-subunits under the usual buffer conditions. The modified amino acids are alpha-Tyr300, alpha-Tyr244 and beta-Tyr368. Binding of FSBA, at least up to 3 mol/mol F1, does not result in loss of bound ADP, whether the starting enzyme contains 2, 3 or 4 bound nucleotides. Added adenine nucleotides compete with FSBA only for binding that results in modification of beta-subunits, shifting the alpha/beta ratio of bound label to higher values. It is concluded that the alpha-subunits contain two hydrophobic pockets for the binding of nucleoside moieties, with a different orientation relative to the P-loop. One pocket contains alpha-Tyr244 and alpha-Tyr300, the other beta-Tyr368. Since, however, in the binding of adenine nucleotide di- or triphosphates the P-loop is involved, only one of these ligands can bind per subunit. The previously not understood binding characteristics of several substrate analogues have now become interpretable on the assumption that also the structurally homologous beta-subunits contain 2 pockets where nucleoside moieties can bind. The kinetic effects of FSBA binding indicate that the first FSBA binds at the regulatory site that has a high affinity for ADP and pyrophosphate. Binding of pyrophosphate at this high-affinity regulatory site increases the Vmax of the enzyme, while binding at a second regulatory site, a low-affinity site, increases the rate of binding of FSBA with a factor of about 3. Binding of bicarbonate at this latter site is responsible for the disappearance of the apparent negative cooperativity of the ATPase activity.     

Frequency of MNSs blood groups in south eastern Nigeria

A total of 614 inhabitants of Calabar, south eastern Nigeria were tested with anti-M, anti-N and anti-S sera to determine the frequency of MNSs blood groups in that population. The results showed that neither ABO blood group nor sex has influence on the occurrence of MNSs blood groups in the population. It was also observed that whereas S antigen was more frequently associated with M antigen, s associated more frequently with N antigen. One half of the Su antigen occurred with MN phenotype. Significantly, the Su antigen occurred in 94% of the male subjects.     

The von Hippel-Lindau tumor suppressor protein is required for proper assembly of an extracellular fibronectin matrix

Fibronectin coimmunoprecipitated with wild-type von Hippel-Lindau protein (pVHL) but not tumor-derived pVHL mutants. Immunofluorescence and biochemical fractionation experiments showed that fibronectin colocalized with a fraction of pVHL associated with the endoplasmic reticulum, and cold competition experiments suggested that complexes between fibronectin and pVHL exist in intact cells. Assembly of an extracellular fibronectin matrix by VHL-/- renal carcinoma cells, as determined by immunofluorescence and ELISA assays, was grossly defective compared with VHL+/+ renal carcinoma cells. Reintroduction of wildtype, but not mutant, pVHL into VHL-/- renal carcinoma cells partially corrected this defect. Finally, extracellular fibronectin matrix assembly by VHL-/- mouse embryos and mouse embryo fibroblasts (MEFs), unlike their VHL+/+ counterparts, was grossly impaired. These data support a direct role of pVHL in fibronectin matrix assembly.     

Acute pancreatitis induces cytokine production in endotoxin-resistant mice

PURPOSE: An automated contour detection algorithm was developed for the objective and reproducible quantitative analysis of velocity-encoded MR studies of the ascending aorta. METHOD: The only user interaction required is the manual definition of a center point inside the cross-section of the aorta in one of the available images. The automated contour detection algorithm detects an initial model contour in this image and subsequently corrects for motion and deformation of the aortic cross-section in each of the acquired images over the complete cardiac cycle using dynamic programming techniques. Integrating the flow velocity values for each pixel within the detected contour results in an instantaneous flow value. Next, by integrating the instantaneous flow values for each acquired phase over the complete cardiac cycle, left ventricular stroke volume measurement could be obtained. The results of the automated method were compared with results derived from manually traced contours in MR studies from 11 healthy volunteers. RESULTS: An excellent agreement in stroke volume measurements was observed: signed difference 0.61+/-1.15%. Inter- and intraobserver variabilities were <2% for both manual and automated image analysis methods. Manual tracing of contours required on the order of 10 min; the analysis time for automated contour detection was <6 s/study. CONCLUSION: The present contour detection allows fast and reliable left ventricular stroke volume measurements from aortic flow studies using velocity-encoded MR studies in healthy volunteers. Further study is required to assess the accuracy and reproducibility of the algorithm in patients with aortic and aortic valve disease.     

新型双酚类抗氧剂2,2′-亚甲基双（6-壬基对甲酚）的合成

抗氧剂2,2′-亚甲基双（6-壬基对甲酚）是新型大分子量液体双酚类抗氧剂,我们以对甲酚为原料,通过酯化反应、Fries重排反应、傅克酰化反应、羰基Clemmensen还原反应和酸介导的甲醛亲和取代反应合成了2,2′-亚甲基双（6-壬基对甲酚）,中间体和最终产物都通过NMR、MS表征确证,以大于90%的总收率实现产品的合成。     

CuMnNiCo钎料钎焊MGH956合金接头组织及力学性能研究

采用自制的CuMnNiCo钎料对氧化物弥散强化(ODS)合金MGH956进行钎焊实验,分析了钎焊过程中各种组织的形成过程,研究了不同的钎焊温度对接头组织和性能的影响。结果表明:在1000~1050℃保温20min工艺下钎焊MGH956合金,均可获得良好的钎焊成形效果,钎焊接头由钎缝中心区的Cu-Mn基固溶体和两侧扩散反应区的Fe-Mn基固溶体组成,并含有三种不同的化合物相。钎焊温度为1030℃和1050℃时,接头的室温拉伸断裂发生在钎缝中心处,断口主要呈沿晶脆性断裂特征。钎焊温度的提高使沿晶界分布的脆性(Mn,Ni)-Si相减少,有利于改善钎焊接头强度,钎焊接头的室温抗拉强度最高可达到母材强度的75%。     

基于全站同步时钟扩展装置的智能变电站同步整组 试验方法的研究

论述了智能变电站模拟量分布式采样和数据同步的方式及带来的同步整组试验问题,对比分析了两种常规的同步整组试验方法的优缺点和适应性,提出了一种基于全站同步时钟系统扩展信号的同步整组试验方法。该方法巧妙地利用了布置在变电站就地各个间隔汇控柜内的同步信号作为测试输出的基准,具有接线简单、同步精度高的优点,实验室及现场测试的结果表明该方法具有良好的适应性。