Migratory pattern of zoonotic Toxocara cati and T. canis in experimentally infected pigs.

BACKGROUND: Over a billion people are infected with Toxocara canis or T. cati, the roundworms of dogs and cats. Historically, T. canis has been considered the main species responsible for human toxocarosis, but as serodiagnosis cannot discriminate between the two species, this remains unresolved. We used pigs as a relevant large animal model for human infection to assess the migratory pattern of T. cati and T. canis. METHODS: Pigs were inoculated with T. cati or T. canis eggs or PBS (negative controls) and necropsied 14 or 31 days later. Different organs and tissues were examined for parasites and pathological changes. RESULTS: Overall, the two parasite species had a similar migration pattern reaching multiple organs and tissues, including the mesenteric lymph nodes, liver, lungs, and diaphragm. We recovered larvae of both species in the brain, suggesting that T. cati also can cause neurological toxocarosis in humans. Both species induced systemic eosinophilia and histopathological changes in the lungs, livers, and mesenteric lymph nodes. CONCLUSION: This study emphasises the importance of T. cati as a zoonotic agent and the need to develop diagnostic methods that can differentiate between sources of infection in humans.

Cystitis: significant associations between pathology, histology, and quantitative bacteriology in sows, a cross-sectional study.

BACKGROUND: The importance of cystitis in pig production is controversial and sparse information is available on its frequency and etiology in sows. The aim of this study was to determine the prevalence of bacteriuria, macroscopical and histological lesions of the urinary bladder in culled sows. Urinary bladders and urine samples were obtained from 176 culled sows at slaughter. The urine samples collected by cystocentesis were analyzed to determine bacterial content and pathological findings, macroscopic as well as microscopic, of the bladder were recorded for each sow. RESULTS: The prevalence of bacteriuria, defined by bacterial concentrations ≥ 103 colony forming units per mL of urine, was 34%. Escherichia coli was isolated from 69% of the samples with bacteriuria. Redness of the mucosa was the most frequently observed macroscopic change of the bladder. Intense redness and presence of pus was considered significant pathological changes and occurred in 27% of the urinary bladders. The histopathological examination showed that mononuclear cells were the predominant type of cell infiltration in the bladder mucosa, while neutrophils occurred in very few samples. The criteria for cystitis determined by histopathology were met in 46% of the samples. The criteria were based on presence of hyperemia, edema, and inflammatory cell reaction defined as 40 or more neutrophils or mononuclear cells per high power field. All three indicators of cystitis were significantly associated with each other (p < 0.05) at sow level. CONCLUSION: This study shows that signs of cystitis are common in culled sows. The prevalence of cystitis was 34% based on bacteriological examination, 27% based on macroscopic examination and 46% based on histological examination. Significant associations were found between the three indicators of cystitis: bacteriuria, pathological and histological lesions of the bladder. Based on macroscopic changes and histopathology of the bladder, the cut-off of ≥ 103 colony forming units per mL of urine seems to be appropriate for assessing urine cultures obtained by cystocentesis.

Staphylococcus aureus infected embolic stroke upregulates Orm1 and Cxcl2 in a rat model of septic stroke pathology.

OBJECTIVE: Ischaemic brain lesions and brain abscesses are frequent in both human and animal cases of septic embolic stroke. However, existing models of brain infection do not reflect central aspects of septic embolic stroke. Our aim was to compare septic and non-septic embolic stroke in order to identify gene expressions, inflammatory mediators and brain damage in a rat model. METHODS: We created precisely located focal brain infarcts in a rat model of Staphylococcus aureus infected embolic stroke. To cause septic embolic stroke we used a fibrin-rich embolus with bacteria, while every rat in the control group received a non-infected embolus. 64 rats were randomized to receive sham-surgery, sterile embolic stroke or septic embolic stroke. All groups were compared for brain pathology, mortality, gene expressions and inflammatory mediators using histology and reverse transcription quantitative real-time PCR. RESULTS: Although infarct volumes did not differ, septic embolic stroke caused higher mortality than sterile embolic stroke (p=  0.002). Brain abscesses were observed only in the septic group. Approximately 400-500 fold increases were observed for Orm1 and Cxcl2 respectively (1.00E-08 < p < 1.92E-07) in the septic group compared to the sterile group, and these were the most dramatically regulated genes in septic embolic stroke compared to sterile embolic stroke. CONCLUSIONS: Septic embolic stroke caused brain abscesses, increased mortality and upregulated Orm1 and Cxcl2 gene expressions compared to non-infected embolic stroke. The dramatic Orm1 increase observed in the septic group is unprecedented and suggests a significant biological role of Orm1 during septic neuroinflammation.

Functional characterization of a porcine emphysema model.

BACKGROUND: Lung emphysema is a central feature of chronic obstructive pulmonary disease (COPD), a frequent human disease worldwide. Cigarette smoking is the major cause of COPD, but genetic predisposition seems to be an important factor. Mutations in surfactant protein genes have been linked to COPD phenotypes in humans. Also, the catalytic activities of metalloproteinases (MMPs) are central in the pathogenesis of emphysema/COPD. Especially MMP9, but also MMP2, MMP7, and MMP12 seem to be involved in human emphysema. MMP12-/- mice are protected from smoke-induced emphysema. ITGB6-/- mice spontaneously develop age-related lung emphysema due to lack of ITGB6-TGF-ß1 regulation of the MMP12 expression. METHODS: A mutated pig phenotype characterized by age-related lung emphysema and resembling the ITGB6-/- mouse has been described previously. To investigate the emphysema pathogenesis in this pig model, we examined the expression of MMP2, MMP7, MMP9, MMP12, and TGF-ß1 by quantitative PCR (qPCR). In addition, immunohistochemical stainings of the lungs with SP-B, SP-C, MMP9, and MMP12 antibodies were performed. The haematologic/immunologic status of the pigs also was studied. RESULTS: The qPCR study showed no difference between pigs with and without emphysema, and no systemic differences were indicated by the haematologic and immunologic studies. However, the immunohistochemical stainings showed an increased expression of MMP9 and MMP12 in older, mutated pigs (with emphysema) compared with normal and young mutated pigs (without emphysema). CONCLUSIONS: The pig model is comparable to human emphysema patients and the ITGB6-/- mouse model with respect to both morphology and functionality.

Embolic encephalitis in a porcine model of endocarditis.

BACKGROUND: Endocarditis is a severe disease in which neurological complications are frequent and associated with increased mortality and complex disease management. In the present study, the pig was evaluated as a model of embolic encephalitis as a complication of experimental infective endocarditis. MATERIALS AND METHODS: Brains from pigs with experimental Staphylococcus aureus-associated infective endocarditis (IE; n=2), experimental non-bacterial thrombotic endocarditis (NBTE; n=5), experimental S. aureus sepsis without endocarditis (SNE; n=3) and saline controls (n=3), were used. The brains were examined for lesions macroscopically, histologically and immunohistochemically. RESULTS: Lesions of focal encephalitis were found in the IE and SNE pigs, at considerably higher numbers in the IE pigs. Furthermore, microabscesses were common in the IE pigs, which fits the association between brain abscesses and S. aureus-associated endocarditis in humans. CONCLUSION: Experimental porcine S. aureus-associated endocarditis is advantageous for studying neurological complications, such as brain abscess formation, as a result of endocardial bacterial seeding.

A porcine model of acute, haematogenous, localized osteomyelitis due to Staphylococcus aureus: a pathomorphological study.

A porcine model of acute, haematogenous, localized osteomyelitis was established. Serial dilutions of Staphylococcus aureus [5-50-500-5000-50 000 CFU/kg body weight (BW) suspended in saline or saline alone] were inoculated into the right brachial artery of pigs (BW 15 kg) separated into six groups of two animals. During the infection, blood was collected for cultivation, and after the animals were killed from day 5 to 15, they were necropsied and tissues were sampled for histopathology. Animals receiving ≤500 CFU/kg BW were free of lesions. Pigs inoculated with 5000 and 50 000 CFU/kg BW only developed microabscesses in bones of the infected legs. In the centre of microabscesses, S. aureus was regularly demonstrated together with necrotic neutrophils. Often, bone lesions resulted in trabecular osteonecrosis. The present localized model of acute haematogenous osteomyelitis revealed a pattern of development and presence of lesions similar to the situation in children. Therefore, this model should be reliably applied in studies of this disease with respect to e.g. pathophysiology and pathomorphology. Moreover, because of the regional containment of the infection to a defined number of bones, the model should be applicable also for screening of new therapy strategies.

Safety pharmacology, toxicology and pharmacokinetic assessment of human Gc globulin (vitamin D binding protein).

Gc globulin is an important protein of the plasma actin-scavenger system. As such, it has been shown to bind free actin and prevent hypercoagulation and shock in patients with massive actin release resulting from severe tissue injuries. Treatment of such patients with Gc globulin could therefore potentially be life-saving. This article presents pre-clinical toxicology experiments conducted on purified plasma-derived human Gc globulin. The Gc globulin formulation was shown to be stable for at least 4 years with full retention of actin-binding capacity. In vitro studies did not reveal activation of the kallikrein system or the complement system and cellular studies showed no toxic effects on a variety of human cell lines. In vivo studies showed no acute toxic effects in mice, rats or guinea pigs upon intravenous infusion. A 14-day local tolerance study in rabbits showed no adverse effects, and 14-day toxicity studies in rats and horses did not show any unwanted reactions. In a 14-day toxicology study in beagle dogs, formation of antibodies was seen and in the end of the study period, three out of four dogs showed clinical immunological reactions, which could be ascribed to the formation of antibodies. The half-life, T, for human Gc globulin was 12 hr in rats, 16 hr in horses and 30 hr in dogs. The safety profile of plasma-derived Gc globulin is concluded to be consistent to that required for use in man.

A non-traumatic Staphylococcus aureus osteomyelitis model in pigs.

BACKGROUND: The propensity for bacterial localization within bones of juvenile pigs is similar to the situation in humans, where haematogenously based osteomyelitis most commonly occurs in infants and children. In both pigs and humans, Staphylococcus aureus is a dominant cause of pyaemic lesions including osteomyelitis. The aim of the present study was to evaluate the pig as a model for the development of osteomyelitis following haematogenous spread of S. aureus. MATERIALS AND METHODS: Twelve animals were challenged intravenously once or twice with 1x10(8) bacteria/kg body weight and euthanased consecutively from 6 h to 48 h after challenge. Following euthanasia, tissues were sampled from the lungs and bones for histology and immunohistochemical staining of vessels, different inflammatiory cells, apoptosis cells, and S. aureus. RESULTS: Disseminated microabscesses developed within the lungs by 6 h but had disappeared at 48 h. Within the metaphyseal area of bones, microabscesses developed after 12 h and progressed until 48 h after challenge. Within bones, lesions were localized in separate foci from where the infection progressed towards the growth plate, which was in some cases bypassed due to bacterial spread through transphyseal vascular channels. Often, bone lesions resulted in trabecular osteosis, in which apoptotic cells were sometimes present. CONCLUSION: The model revealed a pattern of development and presence of lesions similar to the frequently occurring osteomyelitic lesions, especially in pre-pubertal children following haematogenous spread of S. aureus. Therefore, this model can be reliably applied in studies of this disease with respect to pathophysiology, pathomorphology, impact of strain virulence, and therapy.