Effector ExoU from the type III secretion system is an important modulator of gene expression in lung epithelial cells in response to Pseudomonas aeruginosa infection

Pseudomonas aeruginosa is an important pathogen in immunocompromised patients and secretes a diverse set of virulence factors that aid colonization and influence host cell defenses. An important early step in the establishment of infection is the production of type III-secreted effectors translocated into host cells by the bacteria. We used cDNA microarrays to compare the transcriptomic response of lung epithelial cells to P. aeruginosa mutants defective in type IV pili, the type III secretion apparatus, or in the production of specific type III-secreted effectors. Of the 18,000 cDNA clones analyzed, 55 were induced or repressed after 4 It of infection and could be classified into four different expression patterns. These include (i) host genes that are induced or repressed in a type III secretion-independent manner (32 clones), (ii) host genes induced specifically by ExoU (20 clones), and (iii) host genes induced in an ExoU-independent but type III secretion dependent manner (3 clones). In particular, ExoU was essential for the expression of immediate-early response genes, including the transcription factor c-Fos. ExoU-dependent gene expression was mediated in part by early and transient activation of the AN transcription factor complex. In conclusion, the present study provides a detailed insight into the response of epithelial cells to infection and indicates the significant role played by the type III virulence mechanism in the initial host response.

Transient prenatal vitamin D deficiency is associated with hyperlocomotion in adult rats

Rat experiments have shown that prenatal Vitamin D deficiency leads to altered neonatal brain morphology, cell density and neurotrophin expression. In the current study we examined the hypothesis that Vitamin D deficiency during early development alters adult behaviour even when there is an intervening period in which the animal receives normal Vitamin D in later development. Rats were conceived and born to Vitamin D deficient dams (Birth); conceived, born and weaned from Vitamin D deficient dams (Weaning); or deficient in Vitamin D from conception to 10 weeks of age (Life). Litters were standardized to three males and three females per litter. All rat offspring were rendered normocalcaemic with calcium supplemented water (2 mM) after weaning. Control animals were born to mothers fed a normal diet but subject to similar litter size and calcium supplementation. At 10 weeks all animals were tested on the holeboard test, elevated plus maze test, social interaction observation, acoustic startle response test, prepulse inhibition of the acoustic startle response and a forced swim test. Early Vitamin D deficiency (Birth group) enhanced locomotion in the holeboard test and increased activity in the elevated plus maze. Thus, transient prenatal Vitamin D deficiency induces hyperlocomotion in adulthood, without severe motor abnormalities. (C) 2004 Elsevier B.V. All rights reserved.

Effect of body position on transient evoked accoustic emissions: The clinical perspective

The present study investigated body position effects on transient evoked otoacoustic emission (TEOAE) recordings of clinical significance. Sixty adults (30 males, 30 females) were assessed using the Otodynamics ILO88 Analyzer in three positions (sitting, supine, and side-lying). Results indicated significant positional effects on the TEOAE parameters of A-B difference, noise, whole wave reproducibility, and response levels. These differences included higher noise levels in supine and side-lying positions in comparison to the upright sitting position. Lower whole wave reproducibility measurements, and higher response amplitudes, in the side-lying position compared with supine and seated positions were also observed. No significant effects were evident for signal-to-noise ratio or band reproducibility. Given the lack of significant body position effects on these latter parameters and the infrequent clinical use of the other parameters in isolation, there was no evidence to suggest the future need for major review of current pass/fail criteria or of the standard test protocol.

Synaptic activation of transient receptor potential channels by metabotropic glutamate receptors in the lateral amygdala

Classical mammalian transient receptor potential channels form non-selective cation channels that open in response to activation of phospholipase C-coupled metabotropic receptors, and are thought to play a key role in calcium homeostasis in non-excitable cells. Within the nervous system transient receptor potential channels are widely distributed but their physiological roles are not well understood. Here we show that in the rat lateral amygdala transient receptor potential channels mediate an excitatory synaptic response to glutamate. Activation of group l etabotropic glutamate receptors on pyramidal neurons in the lateral amygdala with either exogenous or synaptically released glutamate evokes an inward current at negative potentials with a current voltage relationship showing a region of negative slope and steep outward rectification. This current is blocked by inhibiting G protein function with GTP-beta-S, by inhibiting phospholipase C or by infusing transient receptor potential antibodies into lateral amygdala pyramidal neurons. Using RT-PCR and Western blotting we show that transient receptor potential 1, transient receptor potential 4 and transient receptor potential 5 are present in the lateral amygdala. Single cell PCR confirms the presence of transient receptor potential 1 and transient receptor potential 5 in pyramidal neurons and we show by co-immunoprecipitation that transient receptor potential 1 and transient receptor potential 5 co-assemble as a heteromultimers in the amygdala. These results show that in lateral amygdala pyramidal neurons synaptically released glutamate activates transient receptor potential channels, which we propose are likely to be heteromultimeric channels containing transient receptor potential 1 and transient receptor potential 5/transient receptor potential 4. (c) 2005 Published by Elsevier Ltd on behalf of IBRO.