R.M. Gil da Costa

Bracken-associated human and animal health hazards: chemical, biological and pathological evidence.

Bracken (Pteridium aquilinum) is a widely distributed carcinogenic fern, to whose toxins human populations are exposed through multiple routes. Animals are also affected by bracken toxins, leading to serious production losses yearly. Accordingly, several governmental reports regarding the safeguard of public health against bracken carcinogens have been recently issued. This review describes the main bioactive compounds identified in bracken and their biological effects at the molecular, cellular, pathological and populational levels, with particular emphasis on ptaquiloside, the main bracken carcinogen. Recent biopathological studies shedding further light on the genotoxicity immunotoxicity and carcinogenicity of ptaquiloside are discussed. Key steps on the long effort to understand bracken toxicology are also reviewed, along with the latest findings on new bracken toxins and human exposures routes. The presence of ptaquiloside and related terpene glycosides in milk, meat and water are of particular concern from the viewpoints of both human and animal health.

Immunohistochemical characterization of 13 canine renal cell carcinomas.

Canine renal cell carcinomas (RCCs) are uncommon aggressive tumors that occur mainly in middle-aged male dogs. Their histologic classification bears no relationship with prognosis, and little information is available concerning their immunohistochemical properties. In this retrospective study, formalin-fixed, paraffin-embedded tissues from 13 canine RCCs were retrieved from the archives, classified histologically, and evaluated immunohistochemically. The dogs were 7 males and 6 females (1 spayed) of 10 different breeds, averaging 8 years in age. The tumors were classified as papillary, tubulopapillary, papillary–cystic, solid, or sarcomatoid. All 13 tumors were immunohistochemically positive for uromodulin, 12 for c-KIT, 11 for vimentin, 9 for wide-spectrum-screening cytokeratins, 7 for cytokeratins AE1/AE3 and carcinoembryonic antigen, 4 for cytokeratins CAM 5.2, and 3 for CD10. All 3 solid RCCs expressed vimentin, c-KIT, and carcinoembryonic antigen and were negative for cytokeratins. All 7 papillary and tubulopapillary tumors expressed vimentin; 6 (86%), cytokeratins; and 6 (86%), c-KIT. Both papillary–cystic RCCs were positive for cytokeratins and c-KIT and negative for vimentin. These results indicate that the different histologic types of RCC have characteristic immunohistochemical profiles and that c-KIT may be involved in the pathogenesis of canine RCC.

An immunohistochemical study of feline endometrial adenocarcinoma.

Feline endometrial adenocarcinomas are uncommon malignant neoplasms that have to date been poorly characterized. The present immunohistochemical study describes the expression of the pancytokeratins AE1 and AE3, cytokeratin-14, vimentin, alpha-actin, cyclo-oxygenase-2, E-cadherin, beta-catenin, the progesterone receptor, the oestrogen receptor and caveolin-1 within normal feline uterine tissue and tissue from six cats with endometrial adenocarcinoma. Synthesis of cyclo-oxygenase-2 and reduced expression of progesterone receptors may be involved in the neoplastic transformation of feline endometrium. The loss of cellular adhesion that occurs within these tumours does not require down-regulation of E-cadherin expression and nuclear translocation of beta-catenin is not a feature of these neoplasms.

Ultrasonographic, thermographic and histologic evaluation of MNU-induced mammary tumors in female Sprague-Dawley rats

BACKGROUND As the worldwide breast cancer burden increases, non-invasive tools, such as ultrasonography and thermography are being increasingly sought after. N-methyl-N-nitrosourea-induced rat mammary tumors are important tools to investigate the usefulness of such imaging techniques. OBJECTIVE This study aimed to integrate both ultrasonographic and thermographic approaches to the vascularization and the superficial temperature of chemically-induced rat mammary tumors. MATERIALS AND METHODS Twenty-five female Sprague-Dawley rats were divided into two groups: group I (intraperitoneally administered with N-methyl-N-nitrosourea) and group II (control group). Thirty-five weeks after the administration of the carcinogen, mammary tumors were evaluated using Power Doppler, B Flow and Contrast-enhanced ultrasound, thermography and histology analyses. RESULTS Group I animals showed an average of 2.5 mammary tumors per animal, mostly papillary and cribriform non-invasive carcinomas. B Flow detected higher counts of colour pixels than Power Doppler. Contrast-enhanced ultrasound analysis showed a centripetal enhancement order of contrast agent and clear margins. Maximum tumor temperature and thermal amplitude determined by thermography were significantly correlated with tumor volume and with color pixel density, determined by Power Doppler. CONCLUSION B Flow was more sensitive than Power Doppler in detecting tumor vessels, but Power Doppler correlates with thermographic data concerning superficial temperature and may reflect tumor angiogenesis.

An Update on Canine, Feline and Bovine Papillomaviruses

Over recent years, a growing number of papillomaviruses have been identified, which cause a wide range of lesions in domestic and wild animals. Papillomavirus-induced lesions may have a great impact on animal health, and some diseases observed in farm animals are associated with significant economic losses. This concise review brings together recent advancements on animal papillomavirus research, providing the scientific community and veterinary practitioners with an update on this rapidly evolving field. Among others, bovine, canine and feline papillomaviruses (BPV, CPV and FcaPV) are most extensively discussed, in view of the recent discovery of new viral types and their worldwide importance for animal health. Feline papillomaviruses 2 is an emerging, highly prevalent pathogen in domestic cats, associated with a subset of malignant skin lesions. Aspects related to cross-species infection by BPV and its environmental co-factors are also addressed. Animal papillomaviruses are also fascinating models for studying molecular and cell biology and have recently inspired some major breakthroughs. Overall, it is clear that additional, international and systematic efforts are needed to clarify which lesions are caused by which viral types and to develop experimental models for studying animal papillomavirus.

Long-term exercise training as a modulator of mammary cancer vascularization

BACKGROUND Breast cancer remains a leading cause of death by cancer worldwide. It is commonly accepted that angiogenesis and the expression of angiogenic factors such as vascular endothelial growth factor-A (VEGF-A) is associated with the increased risk of metastasis and poor patient outcome. OBJECTIVE This work aimed to evaluate the effects of long-term exercise training on the growth and vascularization of mammary tumors in a rat model. MATERIALS AND METHODS Fifty female Sprague-Dawley rats were divided into four groups: two N-methyl-N-nitrosourea (MNU)-exposed groups (exercised and sedentary) and two control groups (exercised and sedentary). MNU was administered once, intraperitoneally at 7 weeks-old. Animals were then exercised on a treadmill for 35 weeks. Mammary tumors were evaluated using thermography, ultrasonography [Power Doppler (PDI), B Flow and contrast-enhanced ultrasound (CEUS)], and immunohistochemistry (VEGF-A). RESULTS Both, MNU sedentary and exercised groups showed 100% of tumor incidence, but exercised animals showed less tumors with an increased latency period. Exercise training also enhanced VEGF-A immunoexpression and vascularization (microvessel density, MVD) (p<0.05), and reduced histological aggressiveness. Ultrasound and thermal imaging analysis confirmed the enhanced vascularization of tumors on exercised animals. CONCLUSION Long-term exercise training increased VEGF-A expression, leading to enhanced tumor vascularization and reduced tumor burden, multiplicity and histological aggressiveness.

Hybrid Chitosan Membranes Tested in Sheep for Guided Tissue Regeneration

Previous in vitro studies confirmed an improved cytocompatibility of chitosan-silicate hybrid membranes over chitosan membranes. The main goal of this study was to assess the in vivo histocompatibility of both membranes through subcutaneous implantations at different time periods, 1 week, 1, 2 and 3 months, using a sheep model. Chitosan membranes elicited an exuberant inflammatory response and were consequently rejected. The hybrid chitosan membranes were not rejected and the degree of inflammatory response decreased gradually until the third month of implantation. Histological evaluation also showed that these membranes can be resorbed in vivo. This study demonstrates that the incorporation of silicate into the chitosan solution improves its histocompatibility, indicating that the hybrid chitosan-silicate membranes are suitable candidates to be used in clinical applications.

Challenges with in vitro and in vivo experimental models of urinary bladder cancer for novel drug discovery.

ABSTRACT Introduction: Urinary bladder cancer (UBC) is the second most frequent malignancy of the urinary system and the ninth most common cancer worldwide, affecting individuals over the age of 65. Several investigations have embarked on advancing knowledge of the mechanisms underlying urothelial carcinogenesis, understanding the mechanisms of antineoplastic drugs resistance and discovering new antineoplastic drugs. In vitro and in vivo models are crucial for providing additional insights into the mechanisms of urothelial carcinogenesis. With these models, various molecular pathways involved in urothelial carcinogenesis have been discovered, allowing therapeutic manipulation. Areas covered: This paper provides critical information on existing in vitro and in vivo models to screen the efficacy and toxicity of innovative UBC therapies and point out the challenges for new and improved models. Expert opinion: In our opinion, results obtained with in vitro and in vivo models should be interpreted together, as a set of delicate biological tools that can be used at different stages in the drug discovery process, to address specific questions. With the development of new technologies, new assays and biomarkers are going to play an important role in the study of UBC. The molecular diagnostics and genomic revolution will not only help to develop new drug therapies, but also to achieve tailored therapies.

Trihalomethanes in Liver Pathology: Mitochondrial Dysfunction and Oxidative Stress in the Mouse

Trihalomethanes (THMs) are disinfection byproducts found in chlorinated water, and are associated with several different kinds of cancer in human populations and experimental animal models. Metabolism of THMs proceeds through enzymes such as GSTT1 and CYP2E1 and gives rise to reactive intermediates, which form the basis for their toxic activities. The aim of this study was to assess the mitochondrial dysfunction caused by THMs at low levels, and the resulting hepatic histological and biochemical changes in the mouse. Male ICR mice were administered with two THMs: dibromochloromethane (DBCM) and bromodichloromethane (BDCM); once daily, by gavage, to a total of four administrations. Animals were sacrificed four weeks after DBCM and BDCM administrations. Blood biochemistry was performed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TB), albumin (Alb), total protein (TP), creatinine, and urea. Animals exposed to DBCM and BDCM showed elevated ALT and TB levels (p < 0.05) as compared with controls. Histological analysis confirmed the presence of vacuolar degenerescence and a multifocal necrotizing hepatitis in 33% of animals (n = 2). Mitochondrial analysis showed that THMs reduced mitochondrial bioenergetic activity (succinate dehydrogenase (SQR), cytochrome c oxidase (COX), and ATP synthase) and increased oxidative stress (glutathione S‐transferase (GST)) in hepatic tissues (p < 0.05). These results add detail to the current understanding of the mechanisms underlying THM‐induced toxicity, supporting the role of mitochondrial dysfunction and oxidative stress in liver toxicity caused by DBCM and BDCM.

Ozone therapy prevents the onset of dysplasia in HPV16-transgenic mice—A pre-clinical efficacy and safety analysis

Infection with high-risk human papillomavirus (HPV), most often HPV16, is associated with the development of anogenital and oropharyngeal cancers. Recently, ozone therapy was reported to have considerable efficacy against rabbit VX2 tumors, induced by the cottontail rabbit papillomavirus. The present study aims to determine whether similar results can be obtained in HPV16-transgenic mice, possibly paving the way for new therapeutic options against HPV-induced cancers. HPV16-transgenic and wild-type, female, 20 weeks-old mice were injected intraperitoneally with medical O3/O2 (80░mL/kg, at O3 50░μg/mL), once a day, for 5 consecutive days. The animals were sacrificed at 25 weeks-old, and skin samples were analyzed histologically to study tumour progression. Blood and internal organ samples were used to study toxicological parameters. 85.7% of untreated transgenic mice showed dysplastic skin lesions, compared with 28.6% of O3-treated mice. This was associated with a marked reduction of dermal inflammation associated with those lesions. No significant changes were observed in any toxicological parameters. These preliminary results support the hypothesis that O3 therapy is effective against papillomavirus-induced lesions, particularly against those induced by the most common high-risk virus, HPV16. Further studies are needed to confirm the mechanisms underlying these effects.