Stereoselective synthesis of (R)- and (S)-1,2-diazetidine-3-carboxylic acid derivatives for peptidomimetics.

The stereoselective synthesis of both enantiomers of N-protected 1,2-diazetidine-3-carboxylic acid (aAze) from homochiral glycidol is described. Orthogonal protection of this novel cyclic α-hydrazino acid allows for selective functionalisation at either Nγ or Nδ. This novel peptidomimetic building block was incorporated into the pseudotripeptides Gly-γaAze-Ala and Gly-δaAze-Ala.

Sailing in rough waters: Examining volatility of fMRI noise.

BACKGROUND: The assumption that functional magnetic resonance imaging (fMRI) noise has constant volatility has recently been challenged by studies examining heteroscedasticity arising from head motion and physiological noise. The present study builds on this work using latest methods from the field of financial mathematics to model fMRI noise volatility. METHODS: Multi-echo phantom and human fMRI scans were used and realised volatility was estimated. The Hurst parameter H ∈ (0,1), which governs the roughness/irregularity of realised volatility time series, was estimated. Calibration of H was performed pathwise, using well-established neural network calibration tools. RESULTS: In all experiments the volatility calibrated to values within the rough case, H < 0.5, and on average fMRI noise was very rough with 0.03 < H < 0.05. Some edge effects were also observed, whereby H was larger near the edges of the phantoms. DISCUSSION: The findings suggest that fMRI volatility is not only non-constant, but also substantially more irregular than a standard Brownian motion. Thus, further research is needed to examine the impact such pronounced oscillations in the volatility of fMRI noise have on data analyses.

Development of a lavage procedure to collect lung secretions from chickens for evaluating respiratory humoral immunity.

Mucosal immunology research has been hampered by the difficulty and labour-intensiveness of collecting samples. This is especially true for sites such as the lung, and the present paper describes a simple method for obtaining samples from this organ in chickens. Following sacrifice, the bird was placed on its back and the trachea was cut and exteriorized. Narrow-diameter tubing, to which a 30 ml syringe was attached, was threaded down the trachea to the bronchi and air was evacuated from the lung. Warm buffer was administered and the lung sample then aspirated, processed and frozen. In the current experiment this sampling system was tested on hens that were challenged with Salmonella Enteritidis. Elevated anti-Salmonella Enteritidis antibody levels in lung from infected hens were observed in significantly more infected hens than non-infected control hens in two trials. The simplicity and utility of this sampling system will make it a useful tool for those laboratories wishing to expand their humoral mucosal immunology capabilities, even for study of non-respiratory pathogens.

Simple and rapid methods for detecting Salmonella enteritidis in raw eggs.

The Centers for Disease Control and Prevention estimates there were 300,000 cases of Salmonella enteritidis (SE) in 1997. Egg products were associated with many of the cases. To address this problem, many producers implemented flock surveillance of the SE situation at their facilities. A rapid and simple method for detecting SE from poultry samples is critical for the effective implementation of such testing strategies. A lateral flow device for the detection of SE utilized in this study was manufactured by Neogen, Lansing, MI. The test panel is a presumptive qualitative test system that detects only members of Group D1 Salmonella species. A series of studies were conducted to optimize the test procedure for raw eggs with different sample preparations. A novel antigen extraction method was developed for use with the test panel kit. The detection limit of the test panel kit was increased approximately tenfold when the extraction method was used. Detection of SE was 100% in raw egg pools inoculated with 10 SE cells per ml of egg and incubated at a 1:10 ratio in buffered peptone water (BPW) or tetrathionate brilliant green broth (TBG) for 24 h at 37 degrees C. The developed lateral flow test kit could provide a simple, rapid, and inexpensive method for egg producers and processors to test specifically for Salmonella group D1 serovars, such as SE, in egg samples.

Mucosal humoral immunity to experimental Salmonella enteritidis infection in the chicken crop.

In this report, we show that chickens, infected with Salmonella enteritidis (SE) by oral gavage, produce secretory immunoglobulin As (sIgAs) that specifically bind to numerous SE antigens. Chickens infected with SE showed strong sIgA response against flagella in both bile and crop. The optical density values of enzyme-linked immunosorbent assay (ELISA) tests in positive bile and crop were 1.17 and 0.38, respectively, and were significantly different from those of negative samples. Western immunoblotting revealed that approximately 13.5-, approximately 56-, approximately 62-, approximately 80-, and approximately 143-kD polypeptides were immunodominant proteins in bile, whereas approximately 56-, approximately 62-, and approximately 80-kD polypeptides were found to be strong antigens in crop. These results indicate that the crop may function as another site for mucosal immunity, and the SE flagella-based ELISA of crop samples can provide a useful screening test of SE exposure in chickens.

Serologic detection of experimental Salmonella enteritidis infections in laying hens by fluorescence polarization and enzyme immunoassay.

Detection of infected poultry flocks is essential for controlling eggborne transmission of Salmonella enteritidis to humans. The present study evaluated the detection of antibodies in the sera of experimentally infected chickens by a fluorescence polarization assay with a tracer prepared from the O-polysaccharide of S. enteritidis and an enzyme-linked immunosorbent assay (ELISA) with an S. enteritidis flagellin antigen. In two trials, groups of specific-pathogen-free laying hens were infected orally with either 10(6) or 10(8) colony-forming units (CFU) of S. enteritidis (phage type 13a) or with 10(8) CFU of Salmonella typhimurium. Serum samples were collected before inoculation and at five subsequent weekly intervals. Both assays successfully detected the majority of hens infected with S. enteritidis at either dose level, but they also identified a substantial number of hens infected with S. typhimurium as seropositive. The fluorescence polarization test detected S. enteritidis infection significantly more often and cross-reacted with sera from hens infected with S. typhimurium significantly less often than the ELISA. The fluorescence polarization assay also offered advantages in terms of speed and methodologic simplicity.

Development of a lavage procedure to collect crop secretions from live chickens for studying crop immunity.

The crop (ingluvies), an organ for food storage in most avian species, is located at the base of the oesophagus. Previous work in our laboratory showed that, following infection with Salmonella enteritidis, significant anti-S. enteritidis antibody levels could be found in the crops of these birds. Samples in these previous studies were obtained by flushing the interiors of crops excised from killed birds, which is both labour and animal intensive. A method was sought that allowed multiple sampling of the same birds over time. We found that lavage fluid could be administered directly into the crop down the oesophagus using a narrow-diameter plastic tubing attached to a syringe, and the fluid could then be aspirated back into the syringe. Antibody-containing crop secretions could be collected with minimal discomfort to the test animals. In a study where birds were challenged with S. enteritidis, immunoglobulin A anti-S. enteritidis titres 3 weeks post-challenge were similar in crop samples obtained by live lavage versus the flushing of crops removed from killed birds. Such a sampling procedure may provide researchers with a simple method to follow mucosal immunity in chickens following infection or vaccination regimens.