Intestinal epithelial responses to Salmonella enterica serovar Enteritidis: Effects on intestinal permeability and ion transport

Salmonella infection of chickens that leads to potential human foodborne salmonellosis continues to be a major concern. Chickens serve as carriers but, in contrast to humans, rarely show any clinical signs including diarrhea. The present investigations aimed to elucidate whether the absence of diarrhea during acute Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) infection may be linked to specific changes in the electrophysiological properties of the chicken gut. Immediately after slaughter, intestinal pieces of the mid-jejunum and cecum of either commercial broiler or specific pathogen-free (SPF) chickens were mounted in Ussing chambers in 2 separate experimental series. Living Salmonella Enteritidis (3 × 109) or Salmonella Enteritidis endotoxin (20 mg/L), or both, were added to the mucosal side for 1 h. In both experimental series, the Salmonella infection decreased the trans-epithelial ion conductance Gt (P < 0.05). In the jejunum of SPF chickens, there was also a marked decrease in net charge transfer across the epithelium, evidenced by decreased short-circuit current (Isc, P < 0.05). Interestingly, the mucosal application of Salmonella endotoxin to the epithelial preparations from jejunum and cecum of SPF chicken had an effect similar to living bacteria. However, the endotoxin had no additional effect on the intestinal function in the presence of bacteria. The decreasing effect of Salmonella and or its endotoxin on Gt could be partly reversed by serosal addition of histamine. To our knowledge, this is the first study to address the functional response of native intestinal epithelium of chicken to an in vitro Salmonella infection. For the first time, it can be reported that intestinal ion permeability of chicken decreases acutely by the presence of Salmonella. This type of response could counteract ion and fluid secretion and may thus, at least in part, explain why chickens do not develop overt diarrhea after Salmonella infection

Mass Spectrometry in the Elucidation of the Glycoproteome of Bacterial Pathogens

Presently some three hundred post-translational modifications are known to occur in bacteria in vivo. Many of these modifications play critical roles in the regulation of proteins and control key biological processes. One of the most predominant modifications, N- and O-glycosylations are now known to be present in bacteria (and archaea) although they were long believed to be limited to eukaryotes. In a number of human pathogens these glycans have been found attached to the surfaces of pilin, flagellin and other surface and secreted proteins where it has been demonstrated that they play a role in the virulence of these bacteria. Mass spectrometry characterization of these glycosylation events has been the enabling key technology for these findings. This review will look at the use of mass spectrometry as a key technology for the detection and mapping of these modifications within microorganisms, with particular reference to the human pathogens, Campylobacter jejuni and Mycobacterium tuberculosis. The overall aim of this review will be to give a basic understanding of the current ‘state-of-the-art’ of the key techniques, principles and technologies, including bioinformatics tools, involved in the analysis of the glycosylation modifications

Forming aluminum for solar energy concentrators Quarterly progress report no. 2, 1 Jan. - 31 Mar. 1964

Electroformed aluminum solar reflector

A Polanyian tack: political implications

Intellectual freedom justifies social freedom and is justified as the pursuit of truth. I argue that intellectual freedom is the creative exercise of Polanyian tacit knowing. Polanyian tacit knowing is discovery, a way to new truth. Intellectual freedom, imagined is (1) negative or primarily critical doubt and opposition to Community, Authority and Tradition (CAT) (traditional liberalism); and (2) positive or the over-emphasis of CAT (1) and (2) are untenable and eliminates intellectual freedom by nihilism or totalitarianism; in (1) by nihilism; and (2) by totalitarianism. Nihilism starts in a wrong understanding of truth or how it is pursued while totalitarianism stems from over-emphasis on CAT. Tacit knowledge is a way to analyse (1) the early Polanyi and the tension between social order and freedom; and (2) the late Polanyi and the gap between intellectual freedom and truth. Tacit knowledge presupposes CAT on the from side of tacit knowledge’s notation and overcomes CAT’s constraints by tacit knowing going to truth. Further, by restating his Hungarian Revolution as tacit knowing, tacit knowing is a way to a more truthful CAT, close the uncompleted side of tacit knowledge and solve the original problem of liberalism: its self-destruction. By framing this query in terms of Polanyian intellectual freedom, I establish a way to bring together his early social theory and late epistemology to make an original contribution to Polanyian scholarship. A Polanyian tack ought to be given more thought as to its implications for social theory

QC-DMRG study of the ionic--neutral curve crossing of LiF

We have studied the ionic--neutral curve crossing between the two lowest ^1 Sigma^+ states of LiF in order to demonstrate the efficiency of the quantum chemistry version of the density matrix renormalization group method (QC-DMRG). We show that QC-DMRG is capable to calculate the ground and several low-lying excited state energies within the error margin set up in advance of the calculation, while with standard quantum chemical methods it is difficult to obtain a good approximation to Full CI property values at the point of the avoided crossing. We have calculated the dipole moment as a function of bond length, which in fact provides a smooth and continuous curve even close to the avoided crossing, in contrast to other standard numerical treatments.Comment: 10 pages, 6 figure