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All blood, No stool: enterohemorrhagic Escherichia coli O157:H7 infection
윤장원,Carolyn J. Hovde 대한수의학회 2008 Journal of Veterinary Science Vol.9 No.3
Enterohemorrhagic Escherichia coli serotype O157:H7 is a pathotype of diarrheagenic E. coli that produces one or more Shiga toxins, forms a characteristic histopathology described as attaching and effacing lesions, and possesses the large virulence plasmid pO157. The bacterium is recognized worldwide, especially in developed countries, as an emerging food-borne bacterial pathogen, which causes disease in humans and in some animals. Healthy cattle are the principal and natural reservoir of E. coli O157:H7, and most disease outbreaks are, therefore, due to consumption of fecally contaminated bovine foods or dairy products. In this review, we provide a general overview of E. coli O157:H7 infection, especially focusing on the bacterial characteristics rather than on the host responses during infection.
Lim, Ji Youn,Sheng, Haiqing,Seo, Keun Seok,Park, Yong Ho,Hovde, Carolyn J. American Society for Microbiology 2007 Applied and environmental microbiology Vol.73 No.7
<B>ABSTRACT</B><P><I>Escherichia coli</I> O157:H7 causes hemorrhagic colitis and hemolytic-uremic syndrome in humans, and its major reservoir is healthy cattle. An F-like 92-kb plasmid, pO157, is found in most <I>E. coli</I> O157:H7 clinical isolates, and pO157 shares sequence similarities with plasmids present in other enterohemorrhagic <I>E. coli</I> serotypes. We compared wild-type (WT) <I>E. coli</I> O157:H7 and an isogenic ΔpO157 mutant for (i) growth rates and antibiotic susceptibilities, (ii) survival in environments with various acidity, salt, or heat conditions, (iii) protein expression, and (iv) survival and persistence in cattle following oral challenge. Growth, metabolic reactions, and antibiotic resistance of the ΔpO157 mutant were indistinguishable from those of its complement and the WT. However, in cell competition assays, the WT was more abundant than the ΔpO157 mutant. The ΔpO157 mutant was more resistant to acidic synthetic bovine gastric fluid and bile than the WT. In vivo, the ΔpO157 mutant survived passage through the bovine gastrointestinal tract better than the WT but, interestingly, did not colonize the bovine rectoanal junction mucosa as well as the WT. Many proteins were differentially expressed between the ΔpO157 mutant and the WT. Proteins from whole-cell lysates and membrane fractions of cell lysates were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. Ten differentially expressed ∼50-kDa proteins were identified by quadrupole-time of flight mass spectrometry and sequence matching with the peptide fragment database. Most of these proteins, including tryptophanase and glutamate decarboxylase isozymes, were related to survival under salvage conditions, and expression was increased by the deletion of pO157. This suggested that the genes on pO157 regulate some chromosomal genes.</P>
Witold A. Ferens,Julius Haruna,Rowland Cobbold,Carolyn J. Hovde 대한수의학회 2008 Journal of Veterinary Science Vol.9 No.4
Healthy ruminants carry intestinal Shiga toxin (Stx)- producing Escherichia coli (STEC). Stx has antiviral activities in vitro and STEC numbers correlate with reduced early viremia in sheep experimentally infected with bovine leukemia virus (BLV). This study assessed the impact of intestinal STEC on BLV-induced disease for one year post-BLV-challenge. High STEC scores (CFU/g feces × frequency of STEC-positive samples) correlated with good health, whereas poor weight gain, distress, and tumor development occurred only among animals with low STEC scores. STEC carriage was associated with increased percentages of B cells in peripheral blood.
Phenotypic Diversity of Escherichia coli O157:H7 Strains Associated with the Plasmid O157
Ji Youn Lim,홍준배,Haiqing Sheng,Smriti Shringi,Thomas E. Besser,Carolyn J. Hovde,Rajinder Kaul 한국미생물학회 2010 The journal of microbiology Vol.48 No.3
Escherichia coli O157:H7, a food-borne pathogen, causes hemorrhagic colitis and the hemolytic-uremic syndrome. A putative virulence factor of E. coli O157:H7 is a 60-MDa plasmid (pO157) found in 99% of all clinical isolates and many bovine-derived strains. The well characterized E. coli O157:H7 Sakai strain (Sakai) and its pO157-cured derivative (Sakai-Cu) were compared for phenotypic differences. Sakai-Cu had enhanced survival in synthetic gastric fluid, did not colonize cattle as well as wild-type Sakai, and had unchanged growth rates and tolerance to salt and heat. These results are consistent with our previous findings with another E. coli O157:H7 disease outbreak isolate ATCC 43894 and its pO157-cured (43894-Cu). However, despite the essentially sequence identical pO157 in these strains, Sakai-Cu had changes in antibiotic susceptibility and motility that did not occur in the 43894-Cu strain. This unexpected result was systematically analyzed using phenotypic microarrays testing 1,920 conditions with Sakai, 43894, and the plasmid-cured mutants. The influence of the pO157 differed between strains on a wide number of growth/survival conditions. Relative expression of genes related to acid resistance (gadA, gadX, and rpoS) and flagella production (fliC and flhD) were tested using quantitative real-time PCR and gadA and rpoS expression differed between Sakai-Cu and 43894-Cu. The strain-specific differences in phenotype that resulted from the loss of essentially DNA-sequence identical pO157 were likely due to the chromosomal genetic diversity between strains. The O157:H7 serotype diversity was further highlighted by phenotypic microarray comparisons of the two outbreak strains with a genotype 6 bovine E. coli O157:H7 isolate, rarely associated with human disease.
Patchy approximate explicit model predictive control
Nguyen Hoai Nam,Sorin Olaru,Morten Hovd 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
Multiparametric quadratic programming (MPQP) can be used to construct an off-line solution to constrained linear model predictive control. The result is a piecewise linear state feedback defined over polyhedral cells of the state space. However, with high dimensional problems, coding and implementation of this solution may be very burdensome for the available hardware, due to the high number of polyhedral cells in the state space partition. In this paper we provide an algorithm to find an approximate solution to MPQP, which is obtained by linear interpolation of the exact solution at the vertices of a feasible set and the solution of linear quadratic(LQ) problem. Based on a patchy control technique, we assure robust closed loop stability in the presence of additive measurement noise despite the presence of discontinuities at the switch between the regions in the state space partition.