The Mast Cell Degranulator Compound 48/80 Directly Activates Neurons

Background Compound 48/80 is widely used in animal and tissue models as a “selective” mast cell activator. With this study we demonstrate that compound 48/80 also directly activates enteric neurons and visceral afferents. Methodology/Principal Findings We used in vivo recordings from extrinsic intestinal afferents together with Ca++ imaging from primary cultures of DRG and nodose neurons. Enteric neuronal activation was examined by Ca++ and voltage sensitive dye imaging in isolated gut preparations and primary cultures of enteric neurons. Intraluminal application of compound 48/80 evoked marked afferent firing which desensitized on subsequent administration. In egg albumen-sensitized animals, intraluminal antigen evoked a similar pattern of afferent activation which also desensitized on subsequent exposure to antigen. In cross-desensitization experiments prior administration of compound 48/80 failed to influence the mast cell mediated response. Application of 1 and 10 µg/ml compound 48/80 evoked spike discharge and Ca++ transients in enteric neurons. The same nerve activating effect was observed in primary cultures of DRG and nodose ganglion cells. Enteric neuron cultures were devoid of mast cells confirmed by negative staining for c-kit or toluidine blue. In addition, in cultured enteric neurons the excitatory action of compound 48/80 was preserved in the presence of histamine H1 and H2 antagonists. The mast cell stabilizer cromolyn attenuated compound 48/80 and nicotine evoked Ca++ transients in mast cell-free enteric neuron cultures. Conclusions/Significance The results showed direct excitatory action of compound 48/80 on enteric neurons and visceral afferents. Therefore, functional changes measured in tissue or animal models may involve a mast cell independent effect of compound 48/80 and cromolyn

The role of cortistatin in the human immune system

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Environmental Legionella spp. collected in urban test sites of South East Queensland, Australia, are virulent to human macrophages in vitro

© 2015 Institut Pasteur. Legionellae are frequent contaminants of potable water supplies, resulting in sporadic infections and occasional outbreaks. Isolates of Legionella were collected from urban test sites within South East Queensland and evaluated for their virulence potential in vitro. Two strains (from the species Legionella londiniensis and Legionella quinlivanii) were demonstrated to have the ability to infect human macrophages, while a strain from the species Legionella anisa did not maintain an infection over the same time course. This suggests that the spectrum of urban environmentally associated Legionella with potential to cause human disease might be greater than currently considered

Genetic characterization of Listeria monocytogenes isolates from food processing facilities before and after postcook chiller heat treatment

Possible selection for and establishment of stress-resistant Listeria monocytogenes variants as a consequence of heating interventions is of concern to the food industry. Lineage analysis and multilocus variable number tandem repeat analysis (MLVA) was performed on 20 L. monocytogenes isolates, of which 15 were obtained before and 5 were obtained after heat treatment of a postcook meat chiller. The ctsR gene (a class III heat shock gene regulator) from 14 isolates was amplified and sequenced because previous work has indicated that spontaneous mutations can occur in this gene during heat treatment. Heat treatment of the meat chiller did not significantly change the relative abundance of the various L. monocytogenes lineages; lineage II strains (less-heat-resistant isolates) dominated both before and after heat treatment. MLVA typing confirmed that some isolates of L. monocytogenes occur both before and after heat treatment of the chiller. No isolate of L. monocytogenes indicated any likely functionally significant mutations in ctsR. This study indicates the absence of any obvious difference in the profiles of L. monocytogenes strains obtained before and after heat treatment of a meat chiller, based on the characteristics examined. Although this finding supports the effectiveness of heat treatment, the limited number of strains used and characteristics examined mean that further study on a larger scale is required before firm conclusions can be drawn

The prevalence and concentration of bacillus cereus in retail food products in Brisbane, Australia

Illness associated with Bacillus cereus may be underreported as very few of those affected seek medical attention owing to the mild nature and short duration of symptoms. For this reason there is little information on the prevalence and concentration of this pathogen in retail food products. A total of 1263 retail food samples were examined for B. cereus using the Australian Standard 1766.2.6 (1991): spread plate technique on polymyxin pyruvate egg yolk mannitol bromothymol blue agar, of which the limit of detection was log 10 2.0cfu/g. Bacillus cereus was not detected in samples of skim milk powder, sandwiches, sushi, fresh beef mince, tortillas, or shelf stable stir-fry sauces. Bacillus cereus was detected in the following food samples: uncooked pizza bases (1 of 63 samples, log10 count of 2.0cfu/g), cooked pizzas (8 of 175, mean log10 3.4cfu/g), cooked meat pies (7 of 157, mean log10 2.2cfu/g), cooked sausage rolls (5 of 153, mean log10 2.6cfu/g), processed meats (1 of 350, log10 3.3cfu/g), and raw diced chicken (3 of 55, mean log10 4.3cfu/g). It appears that composite food products have more positive detection samples because the numerous ingredients may introduce spores into the foods. This study provides valuable data on the distribution, prevalence, and concentration of B. cereus in selected retail products. © 2010, Mary Ann Liebert, Inc