A case of antibacterial-responsive mucocutaneous disease in a seven-year-old dwarf lop rabbit (Oryctolagus cuniculus) resembling mucocutaneous pyoderma of dogs.

A seven-year-old, ovariohysterectomised female dwarf lop rabbit (Oryctolagus cuniculus) was referred with severe swelling and erythema of the mucocutaneous junctions of the lips, nares and vulva. Bilateral, severe periocular dermatitis was also present. Heavy pure growths of a member of the Staphylococcus intermedius group were cultured from nasal and aural swabs and skin biopsies. Other possible differential diagnoses were eliminated by standard tests. The clinical features and histopathological characteristics of the biopsies were most consistent with mucocutaneous pyoderma, a dermatosis previously reported in dogs but not in rabbits. Treatment of the bacterial infection with oral marbofloxacin and topical ofloxacin eye drops together with supportive therapy resulted in resolution of the lesions. To the authors' knowledge, this is the first report of mucocutaneous bacterial pyoderma, similar to mucocutaneous pyoderma of dogs, in a rabbit.

Mapping of surrogate markers of cellular components and structures using laser desorption/ionization mass spectrometry.

Laser desorption/ionization mass spectrometry (LDI-MS) has been used to assess the potential of using surrogate markers, bound to cellular structures containing nucleic acids, to image or map the position of these structures within biological samples. In this study, organic dyes were used as markers because of their established use in the histochemical marking of nucleic acids, and also because they are amenable to LDI-MS. Eight cationic dyes were tested and all could be desorbed from nucleic acid samples without additional matrix after specifically binding to these molecules. Methylene Blue was the best of these based on its sensitivity to detection by LDI-MS and the fact that it can be washed from the tissue in areas where it was not specifically bound to provide low-intensity background signals. Experiments are reported which characterize the M(+) ion signal obtained from Methylene Blue with regard to sensitivity, reproducibility and possible use for quantitation. This dye was used to map (with a lateral resolution of 25 microm) several nucleic acid-containing samples spotted on prepared surfaces, and to image the location of nucleic acids in two model tissues, retinal vertical sections and thyroid whole mount sections.

Direct profiling of proteins in biological tissue sections by MALDI mass spectrometry.

The direct profiling of proteins present in tissue sections for several organs of the mouse has been accomplished using matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS). Fresh tissue was sectioned and blotted on a conductive polyethylene membrane. The dried membrane blot was coated with matrix, typically sinapinic acid, and directly analyzed in the mass spectrometer. Generally, well over 100 peptide/protein signals in the 2000-30,000 Da range were observed, with 30-50 having relatively high signal intensities. Analysis of different areas of the same tissue gave remarkably similar mass spectra with greater than 90% homology. However, different parts of a segmented tissue, such as the proximal, intermediate, and distal colon, gave some unique protein signals. After treatment of the tissue blot with protease and subsequent MALDI MS analysis using postsource decay methods for peptide sequencing, some of the proteins were identified. The unique protein profiles measured from these tissue blots also showed differences from strain to strain of the mouse, with genetically similar strains having very similar patterns.

Frequency scan for the analysis of high mass ions generated by matrix-assisted laser desorption/ionization in a paul trap

An ion trap has been modified for the analysis of high mass ions generated by matrix-assisted laser desorption/ionization. Samples are deposited on a probe tip and introduced directly onto the hyperbolically shaped surface of one endcap. All three electrodes - both the endcaps and the ring electrode - are insulated so that the radio frequency (Rf) voltage may be applied to the center ring electrode and the inverted Rf voltage to the endcaps. By using low frequencies (below 100 kHz) and low amplitudes (below 200 V), high mass singly charged ions may be trapped and analyzed by a frequency sweep at constant amplitude. In the high mass range (60-160 kDa), this instrument showed good sensitivity, signal-to-noise ratios, and mass resolution. Copyright 1999 John Wiley & Sons, Ltd.

Combining solid-phase preconcentration, capillary electrophoresis and off-line matrix-assisted laser desorption/ionization mass spectrometry: intracerebral metabolic processing of peptide E in vivo.

The in vivo metabolism of peptide E was studied in the anesthetized rat using a combination of microdialysis sampling, solid-phase preconcentration capillary electrophoresis and imaging matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). The metabolic profile of peptides identified by MALDI/MS showed that the primary enzymatic activity for degradation of peptide E was due to carboxypeptidases and, to a lesser extent, aminopeptidases and some trypsin-like endopeptidases. Over 75 metabolic fragments were detected from the action of these enzymes in vivo.

Automated mass spectrometry imaging with a matrix-assisted laser desorption ionization time-of-flight instrument.

The automated use of a matrix-assisted laser desorption ionization (MALDI) mass spectrometer (MS) is described for image analysis of samples through implementation of new software for instrument control, data acquisition, and data analysis. The software permits automated acquisition of MS MALDI spectra to form an ordered data array and contains display features to provide images at one or more mass-to-charge ratio values. The technique can be used to scan tissue samples, blotted samples, gels, or other sample surfaces where the image analysis of that sample is required. The program achieves a time of typically 1 s per image point, permitting an analysis made up of large numbers of points with high spatial resolution up to 850 dpi. The features of the software are demonstrated in this paper with samples of printed images, where visible images can be compared to those obtained by mass spectrometry. Quantitative aspects are introduced by analyzing a series of sample spots containing different amounts of several proteins.

Studies on the selection of new matrices for ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new group of compounds has been successfully tested as matrices for ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS). Several new matrices for UV-MALDI MS have been found by choosing, as potential matrices, compounds that perform an intramolecular proton transfer along an intramolecular H-bond under UV irradiation. Compounds of this type are, for example, salicylamide, salicylanilide, several ortho-hydroxyacetophenones and ortho-hydroxybenzophenones. The matrix activity of these compounds is compared to the corresponding meta- and para-isomers and to the matrix activity of such well known matrices as 2,5-dihydroxybenzoic acid and 2,4,6-trihydroxyacetophenone. It was found that meta- and para-substituted hydroxycarbonyl compounds show either a significantly lower or no matrix activity compared with the ortho isomers.