The mycotoxin deoxynivalenol facilitates allergic sensitization to whey in mice.

Intestinal epithelial stress or damage may contribute to allergic sensitization against certain food antigens. Hence, the present study investigated whether impairment of intestinal barrier integrity by the mycotoxin deoxynivalenol (DON) contributes to the development of whey-induced food allergy in a murine model. C3H/HeOuJ mice, orally exposed to DON plus whey once a week for 5 consecutive weeks, showed whey-specific IgG1 and IgE in serum and an acute allergic skin response upon intradermal whey challenge, although early initiating mechanisms of sensitization in the intestine appeared to be different compared with the widely used mucosal adjuvant cholera toxin (CT). Notably, DON exposure modulated tight-junction mRNA and protein levels, and caused an early increase in IL-33, whereas CT exposure affected intestinal γδ T cells. On the other hand, both DON- and CT-sensitized mice induced a time-dependent increase in the soluble IL-33 receptor ST2 (IL-1R1) in serum, and enhanced local innate lymphoid cells type 2 cell numbers. Together, these results demonstrate that DON facilitates allergic sensitization to food proteins and that development of sensitization can be induced by different molecular mechanisms and local immune responses. Our data illustrate the possible contribution of food contaminants in allergic sensitization in humans.

Pharmacokinetics of S(+) ketamine derived from target controlled infusion.

BACKGROUND: A computer controlled infusion device for S(+) ketamine was used in combination with a Diprifusor device to provide anaesthesia for 20 ASA I or II patients undergoing elective colonoscopy. The aim of the study was to assess the performance of the pharmacokinetic model for S(+) ketamine used in the delivery algorithm of the device. RESULTS: It was observed that during the first 30 min of infusion there was systematic underprediction by the delivery system of the measured levels of S(+) ketamine. New pharmacokinetic constants were derived from the observed data which provided, on pharmacokinetic simulation, improved prediction of the measured values of S(+) ketamine. Prospective application of this modified model for S(+) ketamine in a further nine study patients was performed and the pharmacokinetic performance of the model was reassessed. The data from all 29 patients was subsequently used to calculate the population distribution of S(+) ketamine clearance. The distribution was found to be normal only in the logarithmic domain. In the normal domain the mode of S(+) ketamine clearance was found to be 35.8 ml kg(-1) min(-1) with 5 and 95% confidence limits of, respectively, 11.5 and 111.1 ml kg(-1) min(-1). CONCLUSION: It was necessary to modify the original published pharmacokinetic parameters incorporated into the S(+) ketamine delivery system in order to simulate improved PK performance during short procedures (<1 h duration) where propofol was concurrently administered. This improved performance was confirmed in a further prospective study.

Shielding of Escherichia coli outer membrane proteins as receptors for bacteriophages and colicins by O-antigenic chains of lipopolysaccharide.

The accessibility of several outer membrane proteins for bacteriophages and colicins in isogenic smooth and rough Escherichia coli strains was investigated. The results show that O antigen carrying lipopolysaccharide is able to prevent access of all phages and colicins tested to their outer membrane protein receptors.

Blood changes in carp (Cyprinus carpio) induced by ulcerative Aeromonas salmonicida infections.

Only recently Aeromonas salmonicida has been recognized as a significant bacterial pathogen in ulcerative disease of cyprinid fish. Our attempts to formulate a vaccine based on bacterial surface antigens were unsuccessful in conferring reliable protection against lethal challenge. This lead us to study pathological changes in the humoral defense system during ulcerative A. salmonicida infection in carp. High numbers of opportunist pathogens such as A. hydrophila and Pseudomonas sp. were frequently recovered from the internal organs of moribund fish, in addition to A. salmonicida. These findings together with leucopenia in moribund fish suggest that pathogenesis is characterized by a state of immune suppression. In addition, fish which had sustained a sublethal infection were not protected against a subsequent lethal challenge. However, fish previously injected with a concentrated and inactivated culture supernatant showed protection. Differential blood cell counts did not differ between experimental and control groups during sublethal infection in contrast to serum proteins. Furthermore infected non-immune carp showed a progressive decrease of immunoglobulin and total serum protein levels before the day of peak mortality whereas protected carp maintained the immunoglobulin concentration despite a decrease in protein. Our observations suggest the involvement of multiple pathogenic events, affecting different parts of the humoral defense system during ulcerative A. salmonicida infection. The immunosuppressive effects can be minimized by prior vaccination with culture supernatant.

Role of the Arg158 residue of the outer membrane PhoE pore protein of Escherichia coli K 12 in bacteriophage TC45 recognition and in channel characteristics.

In order to study the structure-function relationship of the PhoE protein pore we have isolated five independent, TC45-resistant, phoE mutants all of which appeared to produce normal amounts of an electrophoretically altered PhoE protein, designated as PhoE* protein. Nucleotide sequence analysis of the DNA fragments carrying the mutations showed that the mutations all correspond to a G.C to A.T transition at the same place within the phoE gene resulting in a deduced change of amino acid residue arginine 158 into histidine. This result shows that the arginine 158 residue plays an important role in the interaction of the PhoE protein pore with phage TC45. Moreover, studies on the channel properties of the PhoE* protein showed that the PhoE channel has lost part of its preference for negatively charged solutes, as a result of the arginine to histidine change. The results are discussed in terms of the structure-function relationship of PhoE protein as well as in terms of the topological organization of the protein channel in the outer membrane.

Genetics and biochemistry of the peptidoglycan-associated proteins b and c of Escherichia coli K12.

To collect information on synthesis and regulation of the peptidoglycan-associated pore-forming outer membrane proteins b and c, mutants resistant to phages Me1 and TuIa were analyzed. Genetic analysis showed three linkage groups, corresponding with the genes tolF (phenotype b-c+), meoA (phenotype b+c-) and ompB (phenotypes b-c-, b-c+, b++c- and b++c+/-). It has recently been described that also a b+c- phenotype can occur in the latter linkage group [Chai, T., Foulds, J., J. Bacteriol. 130, 781-786 (1977)]. Among ompB (b-c+)/meoA (b+c-) double mutants strains were found with the b+c- phenotype, showing that ompB is not the structural gene for protein b. Studies on purified proteins b and c showed profound differences between the two proteins with respect to the electrophoretic mobility of fragments obtained by treatment with cyanogen bromide, trypsin and chymotrypsin. The amino acid in position three of the amino-termini of proteins b and c, isolated from isogenic strains, were identified as isoleucine and valine respectively. Both the genetic and biochemical results are consistent with a model recently published [Ichihara, S., Mizushima, S., J. Biochem. (Japan) 83, 1095-1100 (1978)] which predicts that tolF and meoA are the structural genes for the proteins b and c respectively and that ompB is a regulatory gene whose product regulates the levels of both proteins.

Mapping of a gene for a major outer membrane protein of Escherichia coli K12 with the aid of a newly isolated bacteriophage.

A method is described for the enrichment of phages which can adsorb to a specific determinant of bacterial cell surfaces. A phage was isolated which absorbs to E. coli cells containing the "major outer membrane= protein c but not to strains that are lacking this protein. With the aid of this phage a gene, meoA which is responsible for the lack of protein c was mapped at 48 min on the linkage map of E. coli K12.