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Quorum-sensing systems regulate the expression of virulence factors in a wide variety of plant and animal pathogens, including members of the Enterobacteriaceae. Studies of Shigella virulence gene expression have demonstrated that maximal expression of genes encoding the type III secretion system and its substrates and maximal activity of this virulence(More)
The ability of Campylobacter jejuni to penetrate normally nonphagocytic host cells is believed to be a key virulence determinant. Recently, kinetics of C. jejuni intracellular survival have been described and indicate that the bacterium can persist and multiply within epithelial cells and macrophages in vitro. Studies conducted by Pesci et al. indicate that(More)
The molecular mechanisms underlying peripheral neuropathies have only been partially elucidated. In particular, the regulatory factors that control the stability and turnover of mature myelin are largely unknown. Transforming growth factor beta 1 (TGF-beta1), and its associated receptors, are expressed by mature Schwann cells. On this basis, we postulated(More)
Fenestrated endothelium lining liver sinusoids forms an ultrastructural sieve between blood and hepatocytes which at physiological perfusion pressures has previously been shown to shield hepatocytes from large triglyceride-rich chylomicrons. In the study reported in this paper, enlargement of endothelial fenestrae at high perfusion pressures has been(More)
Adherence of neutrophils to glomerular basement membrane containing immunoglobulin G aggregates was accompanied by a marked increase in oxygen uptake (eightfold). Very little of the O2 consumed was recovered as superoxide, measured by cytochrome c reduction, or as H2O2, measured with horseradish peroxidase and scopoletin. When neutrophils were incubated(More)
Pathoadaptive mutations improve the fitness of pathogenic species by modification of traits that interfere with factors (virulence and ancestral) required for survival in host tissues. A demonstrated pathoadaptive mutation is the loss of lysine decarboxylase (LDC) expression in Shigella species that have evolved from LDC-expressing Escherichia coli.(More)
Nicotine was fed to rats for 6 weeks, as a weight adjusted dose equivalent to that of a human being smoking 50 to 100 cigarettes per day. Those rats fed nicotine developed hypercholesterolaemia. Scanning electron microscopy showed the porosity of the hepatic sinusoidal endothelium of nicotine fed animals was about 40% that of control animals. The decline in(More)
We report that C. jejuni modifies its outer membrane protein (OMP) repertoire when cultivated under iron-limiting conditions such as during incubation with epithelial cells. To identify genes encoding de novo expressed OMPs, a C. jejuni cosmid library was screened with antisera raised against proteins expressed in the presence of epithelial cells. A single(More)
Following perfusion fixation of livers from fetal, neonatal, and adult sheep, the ultrastructure of the fenestrated sinusoidal endothelium was examined. In contrast to an earlier report which utilized immersion fixation, we found the fenestrae to be unoccluded by diaphragms or basal lamina, thus offering only a discontinuous barrier between the blood and(More)