Pathogenesis of Helicobacter pullorum infections in broilers

Four groups of 23 one-day-old broiler chickens were each inoculated by gavage with a different Helicobacter pullorum strain isolated from humans or poultry. As a control, a fifth group of eight animals was inoculated with phosphate-buffered saline. Faecal samples were collected weekly and tested for the presence of H. pullorum DNA using PCR. At 1, 8, 15, 22 and 42 days postinoculation, birds were euthanized and samples from the liver and intestinal tract were histologically, immunohistochemically and bacteriologically examined. The samples were also tested for the presence of H. pullorum DNA by PCR. All animals remained clinically healthy throughout the experiment although mild lesions in the caeca were present in animals inoculated with H. pullorum. In all H. pullorum-inoculated groups, DNA of this bacterium was detected in faecal samples until 42 days postinoculation. The main site of colonization was the caecum. Immunohistochemical examination revealed that the bacterium was closely associated with the caecal epithelial cells. It was concluded that H. pullorum may colonize the caecum of broilers and is excreted in their faeces until slaughter age. This implies that chicken meat might constitute a source of infection for human beings.     

Tyrosine phosphorylation of annexin II tetramer is stimulated by membrane binding

In the present article we have examined if the interaction of the Ca2+-binding protein, annexin II tetramer (AIIt) with the plasma membrane phospholipids or with the submembranous cytoskeleton, effects the accessibility of the tyrosine phosphorylation site of AIIt. In the presence of Ca2+, pp60(c-src) catalyzed the incorporation of 0.22 +/- 0.05 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5). The Ca2+-dependent binding of AIIt to purified adrenal medulla plasma membrane or phosphatidylserine vesicles stimulated the pp60(c-src)-dependent phosphorylation of AIIt to 0.62 +/- 0.04 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5) or 0.93 +/- 0.07 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5), respectively. Phosphatidylserine- or phosphatidylinositol-containing vesicles but not vesicles composed of phosphatidylcholine or phosphatidylethanolamine, stimulated the phosphorylation of AIIt. In contrast, the binding of AIIt to F-actin resulted in the incorporation of only 0.04 +/- 0.04 mol of phosphate/mol of AIIt (mean +/- S.D., n = 5). These results suggest that the interaction of AIIt with plasma membrane and not the submembranous cytoskeleton, activates the tyrosine phosphorylation of AIIt by inducing a conformational change in the protein resulting in the enhanced exposure or accessibility of the tyrosine-phosphorylation site.     

Presence of macrolide resistance genes in streptococci and enterococci isolated from pigs and pork carcasses

Macrolide and lincosamide (ML)-resistant streptococci and enterococci from tonsillar and colon swabs from 33 pigs and 99 pork carcasses swabs from animals originating from different farms in Belgium were isolated, and their ML resistance phenotypes and genotypes were determined by disk diffusion test and PCR assay, amplifying the ermB gene and the mefA gene. From each of the 33 pigs and 88 of the 99 carcasses' swabs, at least one resistant strain was isolated. The predominant phenotype was the constitutively expressed macrolides, lincosamides and streptogramin B (MLS(B)) phenotype. This phenotype was most often encoded by the ermB gene. A minority of the strains showed the M phenotype encoded by the mefA gene in streptococci, or the L or ML phenotype.     

Release and characterization of single side chains of white cabbage pectin and their complement‐fixing activity

A mixture of single side chains from white cabbage pectin were obtained by anion exchange chromatography after applying mild chemical conditions promoting β‐elimination. These pectin fragments were characterized by their molecular weight distribution, sugar composition, ¹³C‐NMR, and MALDI‐TOF‐MS analysis. These analyses revealed that the large oligosaccharides released by β‐eliminative treatment were composed of α‐1,5 linked arabinosyl residues with 2‐ and 3‐linked α‐arabinosyl side chains, and, or β‐1,4 linked galactosyl side chains. Fractions were tested for complement‐fixing activity in order to determine their interaction with the complement system. These results strongly indicated that there was a minimal unit size responsible for the complement‐fixing activity. Neutral pectin fragments (?8 kDa) obtained from β‐elimination were inactive in the complement system, although they contained a sugar composition previously shown to be highly active. Larger pectin fragments (?17 kDa) retained some activity, but much lower than polymers containing rhamnogalacturonan type 1 (RGI) structures isolated from the same source. This implied that structural elements containing multiple side chains is necessary for efficient complement‐fixing activity.     

On-line liquid chromatography-accurate radioisotope counting coupled with a radioactivity detector and mass spectrometer for metabolite identification in drug discovery and development

A novel detection method combining on-line liquid chromatography-accurate radioisotope counting (LC-ARC, advanced stop flow controller) coupled with a radioactivity detector and mass spectrometer has been developed. One of the major benefits of this method is that this system enhances the sensitivity of radioisotope measurement for metabolite identification in drug metabolism studies. Another advantage to this system is the easy interface with the mass spectrometer, which allows acquisition of mass spectrometric data on-line. For purposes of evaluating this system, in vitro microsomal incubations with [3Hlpropranolol were conducted. On-line separation and identification of [3H]propranolol metabolites was achieved without intensive sample preparation, concentration, or fraction collection. Mass spectrometric analysis showed the presence of propranolol major metabolites formed by hydroxylation, correlating with previously published results. Further evaluations of this system also were conducted using two 14C compounds, which are herein labeled X and Y. As our results show, 14C peaks were detected down to 6 cpm, which is approximately 20 times more sensitive than commercially available flow through radioactivity detectors. The overall results suggest that the combination of LC-ARC with radioactivity detection and mass spectrometry has great potential as a powerful tool for improving the sensitivity of radioisotope measurement in metabolite identification studies during drug discovery and development.     

食用核苷酸

<正> 以前,人们认为核苷酸并非人体所需的营养物质。人们普遍认为生物,包括人类在内,有能力在体内合成对于正常生长和发育所需的核苷酸。如今这个观点发生了改变。有证据表明食用核苷酸对人体起着至关重要的作用。核苷酸是一种低分子量的生物化合物,它几乎在所有的生化反应中部起着非常重要的作用。核苷酸由嘌呤或嘧啶(一种含氮碱基)组成。它们是组成脱氧核糖核酸和核糖核酸的基本物质,在细胞运动和新陈代谢过程中起着很多重要的作用,尤其在许多辅酶中它们也是ATP和其它核苷三磷酸的组成成分。     

Performance assessment of electrospun nanofibers for filter applications

The aim of this study was to evaluate the use of nanofiber microfiltration membranes, spun by an innovative electrospinning technique, in water filtration applications. As such, this study bridges between developments in electrospinning techniques for the production of flat sheet membranes and the application of these membranes in water filtration. Three different applications were examined. First, the use of the membrane (functionalized or non-functionalized) for the removal of pathogens was investigated. Second the electrospun flat sheet membranes were applied in a lab scale submerged membrane bioreactor (MBR). Third, the electrospun membranes were applied as stand-alone filter for water treatment. Next to these applications, physical properties such as clean water permeability (CWP) and strength were also examined. The test showed that the electrospun membranes can be used for water filtration applications, but that further research is necessary towards irreversible fouling properties and level of functionalisation.