Intradermal administration of thymic stromal lymphopoietin induces a T cell- and eosinophil-dependent systemic Th2 inflammatory response

The epithelial-derived cytokine thymic stromal lymphopoietin (TSLP) is sufficient to induce asthma or atopic dermatitis-like phenotypes when selectively overexpressed in transgenic mice, or when driven by topical application of vitamin D3 or low-calcemic analogues. Although T and B cells have been reported to be dispensable for the TSLP-induced inflammation in these models, little is known about the downstream pathways or additional cell types involved in the inflammatory response driven by TSLP. To characterize the downstream effects of TSLP in vivo, we examined the effects of exogenous administration of TSLP protein to wild-type and genetically deficient mice. TSLP induced a systemic Th2 inflammatory response characterized by increased circulating IgE and IgG1 as well as increased draining lymph node size and cellularity, Th2 cytokine production in draining lymph node cultures, inflammatory cell infiltrates, epithelial hyperplasia, subcuticular fibrosis, and up-regulated Th2 cytokine and chemokine messages in the skin. Responses to TSLP in various genetically deficient mice demonstrated T cells and eosinophils were required, whereas mast cells and TNF-alpha were dispensable. TSLP-induced responses were significantly, but not completely reduced in IL-4- and IL-13-deficient mice. These results shed light on the pathways and cell types involved in TSLP-induced inflammation.     

Lack of mutagenic and toxic effects of low dose potassium bromate on kidneys in the Big Blue rat

Potassium bromate (KBrO3) has been classified as a genotoxic carcinogen based on positive results in the Ames test, and chromosome aberration and micronucleus tests. The purpose of the present study was to investigate the dose-response relationship for in vivo mutagenic and toxic effects of KBrO3 in the kidneys of Big Blue rats. In experiment 1, male Big Blue rats were divided into 8 groups. KBrO3 was dissolved in tap water and administered to groups 1-8 at concentrations of 0, 0.02, 0.2, 2, 8, 30, 125 and 500 ppm, respectively, for 16 weeks. Experiment 2 was performed to investigate the effects of KBrO3 at the 0.002 ppm dose approximately contained in the tap water on rat kidneys. Ten Big Blue rats were divided into 2 groups and given distilled water and tap water, respectively, for 16 weeks. In experiment 1, treatment with 500 ppm KBrO3 significantly increased the mutant and total mutation frequencies and frequency of GC to TA transversion of the lacI gene in the kidney compared to non-treatment control group, but 125 ppm and lower doses of KBrO3 had no effects. Histopathologically, renal toxic changes were observed in groups administered KBrO3 at 30 ppm or higher in a dose-dependent manner. PCNA positive cell indices in renal tubular cells were significantly increased in the kidney at doses of 125 and 500 ppm, but not at 30 ppm or lower doses, as compared to the control group. Furthermore, 8-hydroxy-2'-deoxyguanosine formation, a marker of oxidative stress, was significantly increased at 500 ppm. In experiment 2, there were no differences in any parameter between the distilled water and tap water groups. These results suggest the existence of no-effect levels for in vivo mutagenic and toxic effects, proliferation stimulus, and oxidative stress of KBrO3 in rat kidneys.     

Dielectric cytometry with three-dimensional cellular modeling

We have developed what we believe is an efficient method to determine the electric parameters (the specific membrane capacitance C(m) and the cytoplasm conductivity kappa(i)) of cells from their dielectric dispersion. First, a limited number of dispersion curves are numerically calculated for a three-dimensional cell model by changing C(m) and kappa(i), and their amplitudes Deltaepsilon and relaxation times tau are determined by assuming a Cole-Cole function. Second, regression formulas are obtained from the values of Deltaepsilon and tau and then used for the determination of C(m) and kappa(i) from the experimental Deltaepsilon and tau. This method was applied to the dielectric dispersion measured for rabbit erythrocytes (discocytes and echinocytes) and human erythrocytes (normocytes), and provided reasonable C(m) and kappa(i) of the erythrocytes and excellent agreement between the theoretical and experimental dispersion curves.     

Asymmetric synthesis of arylselenoalcohols by means of the reduction of organoseleno acetophenones by whole fungal cells

A series of novel organoseleno acetophenones (3a–f) have been synthesized. The microbial reduction of the seleno ketones (3) has been evaluated using whole cells of Rhizopus oryzae CCT 4964, Aspergillus terreus CCT 3320, A. terreus CCT 4083 and Emericella nidulans CCT 3119. These microorganisms showed Prelog and anti-Prelog stereoselectivity, leading to the arylselenoalcohols in moderate to high enantiomeric excesses. The organoselenium compounds were compatible with the biocatalytic conditions employed.     

Evidence for the presence of DNA-binding proteins involved in regulation of the gene expression of indole-3-pyruvic acid decarboxylase, a key enzyme in indole-3-acetic acid biosynthesis in Azospirillum lipoferum FS.

We isolated the ipdc gene coding for indole-3-pyruvic acid decarboxylase (IPDC), a key enzyme in the indole-3-pyruvic acid pathway for indole-3-acetic acid biosynthesis, in the plant growth-promoting rhizobacterium Azospirillum lipoferum FS. Gel mobility-shift assay showed the presence of two DNA-binding proteins that might be involved in regulation of the ipdc gene expression.     

Bacterial and spontaneous dehalogenation of organic compounds

Only 3 of more than 500 soil enrichments contained organisms able to use 1,9-dichlorononane as a sole carbon source. One isolate, a strain of Pseudomonas, grew on the compound and released much of the halogen as chloride. Resting cells dehalogenated 1,9-dichlorononane aerobically but not anaerobically. Pseudomonas sp. grew on and resting cells dehalogenated 1,6-dichlorohexane, 1,5-dichloroheptane, 2-bromoheptanoate, and 1-chloro-, 1-bromo-, and 1-iodoheptane, but the bacterium cometabolized but did not grow on 3-chloropropionate. p-Methylbenzyl alcohol, chloride, and p-methylbenzoate were formed when resting cells were incubated with alpha-chloro-p-xylene; the first two products were also formed in the absence of the bacteria. Similarly, o- and m-methylbenzyl alcohols were generated from the corresponding chlorinated xylenes in the presence or absence of Pseudomonas sp. The formation of m- and p-chlorobenzoic acid from m- and p-chlorobenzyl chloride proceeded only in the presence of the cells, but p-chlorobenzyl alcohol was generated from p-chlorobenzyl chloride even in the absence of the bacterium. These results are discussed in terms of possible mechanisms of dehalogenation.     

TAK1 kinase switches cell fate from apoptosis to necrosis following TNF stimulation

TNF activates three distinct intracellular signaling cascades leading to cell survival, caspase-8–mediated apoptosis, or receptor interacting protein kinase 3 (RIPK3)–dependent necrosis, also called necroptosis. Depending on the cellular context, one of these pathways is activated upon TNF challenge. When caspase-8 is activated, it drives the apoptosis cascade and blocks RIPK3-dependent necrosis. Here we report the biological event switching to activate necrosis over apoptosis. TAK1 kinase is normally transiently activated upon TNF stimulation. We found that prolonged and hyperactivation of TAK1 induced phosphorylation and activation of RIPK3, leading to necrosis without caspase activation. In addition, we also demonstrated that activation of RIPK1 and RIPK3 promoted TAK1 activation, suggesting a positive feedforward loop of RIPK1, RIPK3, and TAK1. Conversely, ablation of TAK1 caused caspase-dependent apoptosis, in which Ripk3 deletion did not block cell death either in vivo or in vitro. Our results reveal that TAK1 activation drives RIPK3-dependent necrosis and inhibits apoptosis. TAK1 acts as a switch between apoptosis and necrosis.     

Coexistence of different pathways in the metabolism of n-propylbenzene by Pseudomonas sp.

Pseudomonas desmolytica S449B1 and Pseudomonas convexa S107B1 grown on n-propylbenzene oxidized n-propylbenzene to beta-phenylpropionic acid and benzoic acid by initial oxidation of the n-propyl side chain and the following beta-oxidation, respectively. The same strains also oxidized n-propylbenzene to 3-n-propylcatechol by initial oxidation of positions 2 and 3 of the aromatic nucleus. A ring fission product, 2-hydroxy-6-oxononanoic acid, was also isolated from the culture broth. Together with the results of oxygen uptake experiments, the data obtained suggested not only the existence of a reductive step to form 2-hydroxy-6-oxononanoic acid, but also the coexistence of two different pathways in the metabolism of n-propylbenzene by the strains used.