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1.
R.S. Percival P.D. Marsh S.J. Challacombe 《FEMS immunology and medical microbiology》1996,15(1):35-42
Abstract Pyelonephritis is the most common urinary tract infection affecting females of all age groups. Despite concerted efforts the mechanism of renal injury in pyelonephritis is not clearly understood. In the present study we have made an attempt to characterise the mediators of inflammatory insult in an experimental model of ascending pyelonephritis. Mice infected with Escherichia coli O6:K13:H1 were sacrificed at 2, 7 and 14 days post-infection. Luminol-dependent chemiluminescence response, NADPH oxidase, acid phosphatase, β-glucuronidase and N -acetyl-β- d -glucosaminidase activities were monitored in circulating as well as renal phagocytic cells in order to determine the role of reactive oxygen species and lysosomal enzymes in genesis of renal injury. We have demonstrated that reactive oxygen species are generated at the initiation of infection and the levels increase progressively during the course of infection. While intracellular release of lysosomal enzymes was seen in all groups, extracellular release was primarily observed at 7 and 14 days post-infection only. The results indicate that while reactive oxygen species play a significant role in tissue injury during all stages of infection, lysosomal enzyme release in extracellular milieu augments tissue destruction at later stages only. 相似文献
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The extracellular mucilage from Beijerinckia mobilis, a member of the Azotobacteriaceae, after removal of contaminating protein, was separated into a neutral polysaccharide (N-2, 10%); a neutral, dialysable fraction (N-1, 5%), consisting of glucose and oligosaccharides containing glucose, arabinose, and rhamnose; and an acidic polysaccharide (85%). N-2 (mol. wt, 1900) was highly branched and comprised glucopyranose, mannopyranose, and arabinofuranose residues (1:1:1). The various linkages were determined. The acid fraction was a polymer of high molecular weight composed of L-guluronic acid (65%), D-glucose (15%), and D-glycero-D-mannoheptose (20%), together with acetic and pyruvic acids. From the results of methylation, periodate oxidation, and partial hydrolysis, a branched molecule with a backbone of guluronic acid and heptose, and side chains of glucose and guluronic acid is proposed. Pyruvic acid was found to be acetal-linked to 2?5% of the heptose residues. The similarities between this polysaccharide and that from the related species Azotobacter indicum are discussed. 相似文献
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Hunter Elena Percival Benita Ahmad Zeeshan Chang Ming-Wei Hunt John A. Tasker Séverine De Risio Luisa Wilson Philippe B. 《Molecular and cellular biochemistry》2021,476(11):4133-4137
Molecular and Cellular Biochemistry - Chronic kidney disease (CKD) is a renal dysfunction that can lead to high rates of mortality and morbidity, particularly when coupled with late diagnosis. CKD... 相似文献
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Xiao-Zhou Zhang Zuoming Zhang Zhiguang Zhu Noppadon Sathitsuksanoh Yunfeng Yang Y.-H. Percival Zhang 《Applied microbiology and biotechnology》2010,86(2):525-533
Family 48 glycoside hydrolases (cellobiohydrolases) are among the most important cellulase components for crystalline cellulose
hydrolysis mediated by cellulolytic bacteria. Open reading frame (Cphy_3368) of Clostridium phytofermentans ISDg encodes a putative family 48 glycoside hydrolase (CpCel48) with a family 3 cellulose-binding module. CpCel48 was successfully
expressed as two soluble intracellular forms with or without a C-terminal His-tag in Escherichia coli and as a secretory active form in Bacillus subtilis. It was found that calcium ion enhanced activity and thermostability of the enzyme. CpCel48 had high activities of 15.1 U μmol−1 on Avicel and 35.9 U μmol−1 on regenerated amorphous cellulose (RAC) with cellobiose as a main product and cellotriose and cellotetraose as by-products.
By contrast, it had very weak activities on soluble cellulose derivatives (e.g., carboxymethyl cellulose (CMC)) and did not
significantly decrease the viscosity of the CMC solution. Cellotetraose was the smallest oligosaccharide substrate for CpCel48.
Since processivity is a key characteristic for cellobiohydrolases, the new initial false/right attack model was developed
for estimation of processivity by considering the enzyme's substrate specificity, the crystalline structure of homologous
Cel48 enzymes, and the configuration of cellulose chains. The processivities of CpCel48 on Avicel and RAC were estimated to
be ∼3.5 and 6.0, respectively. Heterologous expression of secretory active cellobiohydrolase in B. subtilis is an important step for developing recombinant cellulolytic B. subtilis strains for low-cost production of advanced biofuels from cellulosic materials in a single step. 相似文献
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Colin J. Restall Patrick Williams Michael P. Percival Peter J. Quinn Dennis Chapman 《生物化学与生物物理学报:生物膜》1979,555(1):119-130
A method is reported for the in situ modification of the lipids of isolated spinach chloroplast membranes. The technique is based on a direct hydrogenation of the lipid double bonds in the presence of the catalyst, chlorotris(triphenylphosphine)rhodium (I). The pattern of hydrogenation achieved suggests that the catalyst distributes amongst all of the membranes. The polyunsaturated lipids within the membranes are hydrogenated at a faster rate and at an earlier stage than are the monoenoic lipids.Whilst addition of the catalyst to the chloroplast causes an initial 10–20% decrease in Hill activity, saturation of up to 40% of the double bonds present can be accomplished without causing further significant alterations in photosynthetic electron transport processes or marked morphological changes of the chloroplast structure as observed in the electron microscope. 相似文献
10.
Percival P. Cole 《BMJ (Clinical research ed.)》1913,1(2725):638-638