Atypically located arachnoid cyst in a five-year-old cat.

Arachnoid cysts are cystic lesions that occur in spinal or intracranial locations in the leptomeningeal space. Four intracranial cases have been described in cats, three of which were diagnosed by imaging techniques alone. We now report the clinical, gross and histopathological findings in a 5-year-old, male-neutered European Shorthair cat that presented with chronic, asymmetrical encephalopathy. Using magnetic resonance imaging, a focal, fluid-filled cavity that did not show contrast enhancement was identified in the left temporal and piriform lobes. Necropsy confirmed the presence of a cystic, meningeal cavity filled with clear, serous fluid. Histologically, the cyst had an irregular, hypereosinophilic surface and single psammoma bodies with moderate perivascular oedema in the adjacent neuroparenchyma. Immunohistochemical evidence of meningeal tissue surrounding the cyst confirmed the diagnosis of an arachnoid cyst, which should be considered as a differential diagnosis of intracranial, fluid-filled cavities.

Refolding by high pressure of a toxin containing seven disulfide bonds: bothropstoxin-1 from Bothrops jararacussu.

Aggregation is a serious obstacle for recovery of biologically active heterologous proteins from inclusion bodies (IBs) produced by recombinant bacteria. E. coli transformed with a vector containing the cDNA for Bothropstoxin-1 (BthTx-1) expressed the recombinant product as IBs. In order to obtain the native toxin, insoluble and aggregated protein was refolded using high hydrostatic pressure (HHP). IBs were dissolved and refolded (2 kbar, 16 h), and the effects of protein concentration, as well as changes in ratio and concentration of oxido-shuffling reagents, guanidine hydrochloride (GdnHCl), and pH in the refolding buffer, were assayed. A 32% yield (7.6 mg per liter of bacterial culture) in refolding of the native BthTx-1 was obtained using optimal conditions of the refolding buffer (Tris-HCl buffer, pH 7.5, containing 3 mM of a 2:3 ratio of GSH/GSSG, and 1 M GdnHCl). Scanning electron microscopy (SEM) showed that that disaggregation of part of IBs particles occurred upon compression and that the morphology of the remaining IBs, spherical particles, was not substantially altered. Dose-dependent cytotoxic activity of high-pressure refolded BthTx-1 was shown in C2C12 muscle cells.

Concurrent Helicobacter bilis infection in C57BL/6 mice attenuates proinflammatory H. pylori-induced gastric pathology.

Because coinfections can alter helicobacter gastritis, we investigated whether enterohepatic Helicobacter bilis modulates Helicobacter pylori gastritis in C57BL/6 mice. Thirty mice per group were sham dosed, H. bilis or H. pylori infected, or H. bilis infected followed in 2 weeks by H. pylori and then evaluated at 6 and 11 months postinfection (mpi) for gastritis and premalignant lesions. Compared to H. pylori-infected mice, H. bilis/H. pylori-infected mice at 6 and 11 mpi had less severe gastritis, atrophy, mucous metaplasia and hyperplasia (P < 0.01) and, additionally, at 11 mpi, less severe intestinal metaplasia and dysplasia (P < 0.05). H. bilis/H. pylori-infected mice at 11 mpi exhibited less Ki67 labeling of proliferating epithelial cells, reduced numbers of FoxP3(+) T-regulatory (T(REG)) cells, and lower FoxP3(+) mRNA levels than did H. pylori-infected mice (P < 0.05). Proinflammatory interleukin-1beta (IL-1beta), gamma interferon, and tumor necrosis factor alpha mRNA levels were attenuated in H. bilis/H. pylori-infected mice at 6 and 11 mpi (P < 0.01), although anti-inflammatory IL-10, IL-13, and transforming growth factor beta1 mRNA levels were not consistently impacted by H. bilis coinfection. Decreased pathology in H. bilis/H. pylori-infected mice correlated with higher gastric H. pylori colonization at 6 mpi (P < 0.001) and lower Th1-associated immunoglobulin G2c responses to H. pylori at 6 and 10 mpi (P < 0.05). We hypothesized that reduced pathology in H. bilis/H. pylori-infected mice was due to H. bilis-primed T(REG) cells in the lower bowel that migrated to the gastric compartment and inhibited Th1 responses to subsequent H. pylori infection. Thus, H. pylori-induced gastric lesions may vary in mouse models of unknown enteric helicobacter infection status and, importantly, variable sequelae to human H. pylori infection, particularly in developing countries, may occur where coinfection with lower bowel helicobacters and H. pylori may be common.

Obesity and non-insulin-dependent diabetes mellitus in Swiss-Webster mice associated with late-onset hepatocellular carcinoma.

Genetic mutations resulting in obesity and type 2 diabetes mellitus (T2D) are described for both inbred and outbred mice. However, no known mouse model completely recapitulates human T2D and its comorbidities. We identified a cohort of obese, male, outbred Swiss-Webster (SW) mice as polyuric, polydipsic, glucosuric, and hyperglycemic. Prevalence of glucosuria in the SW colony reached 60% (n=70) in males 8 weeks to 6 months of age. Despite severe obesity in some females, no females were diabetic. Pathologic findings in affected males included cachexia, dilated gastrointestinal tracts with poor muscular tone, pancreatic islet degeneration and atrophy with compensatory metaplasia and/or neogenesis, bacterial pyelonephritis, membranous glomerulopathy, and late-onset hepatic tumors with macrosteatosis, microsteatosis, and hydropic change in aged males. Serum insulin correlated with blood glucose in a nonlinear pattern, suggestive of islet exhaustion. Circulating leptin levels showed a weak inverse correlation with glucose. Diabetic males were bred with obese colony females to produce 20 male and 20 female offspring. Prevalence of diabetes in male offspring was 80% (16/20) with a median age of onset of 18 weeks. By contrast, no diabetic females were identified, despite being significantly more obese than males. Male predominance is likewise a feature of T2D in humans. To our knowledge, this is the first documentation of hepatocellular carcinoma and islet metaplasia and/or neogenesis in a spontaneous outbred mouse model of T2D. The SW availability and histopathologic features represent a promising new model for the study of T2D.

Infestation of wild-caught American bullfrogs (Rana catesbeiana) by multiple species of metazoan parasites.

The American bullfrog (Rana catesbeiana) is an aquatic, carnivorous member of the family Ranidae that is used extensively in physiology education programs and in various physiology, toxicology, sensorineural, and genetics research. Eleven bullfrogs purchased from a vendor distributing wild-caught frogs for use in a physiology research protocol were emaciated but otherwise showed no apparent clinical signs of illness. Necropsies performed on selected emaciated frogs indicated heavy infestation with multiple species of endoparasites. Identified helminths included Gorgodera amplicava, Haematolechus breviplexus, Clinostomum spp, Contracaecum spp, Cosmocercoides dukae, and Eustrongyloides spp. Grossly, parasitized bullfrogs showed encysted trematode larvae within skeletal muscle, nematode impaction of the intestinal tract, and lack of coelemic fat stores. Histopathologic lesions were restricted primarily to the gastrointestinal tract and consisted of parasitic granulomas associated with Contracaecum spp. The parasitic lesions may have been associated with the poor body condition of the bullfrogs. Food crickets maintained in-house were negative for parasite larvae or ova. Heavy parasitism of wild-caught bullfrogs may confound research protocols and markedly impair animal health. We encourage researchers to purchase laboratory-bred and -reared bullfrogs and to routinely monitor the parasite status of colony frogs.