Phase diagram study of a dimerized spin-S zig-zag ladder

The phase diagram of a frustrated spin-S zig-zag ladder is studied through different numerical and analytical methods. We show that for arbitrary S, there is a family of Hamiltonians for which a fully-dimerized state is an exact ground state, being the Majumdar-Ghosh point for a particular member of the family. We show that the system presents a transition between a dimerized phase to a Néel-like phase for S = 1/2, and spiral phases can appear for large S. The phase diagram is characterized by means of a generalization of the usual mean field approximation. The novelty in the present implementation is to consider the strongest coupled sites as the unit cell. The gap and the excitation spectrum is analyzed through the random phase approximation. Also, a perturbative treatment to obtain the critical points is discussed. Comparisons of the results with numerical methods like the Density Matrix Renormalization Group are also presented.

The value of molecular expression of KIT and KIT ligand analysed using real-time polymerase chain reaction and immunohistochemistry as a prognostic indicator for canine cutaneous mast cell tumours

This study investigated the correlation between KIT gene expression determined by immunohistochemistry and real-time polymerase chain reaction (RT-PCR) and the rate of tumour recurrence and tumour-related deaths in dogs affected with mast cell tumour (MCT). Kaplan-Meier curves were constructed to compare tumour recurrence and tumour-related death between patients. The log-rank test was used to check for significant differences between curves. KIT-I, KIT-II and KIT-III staining patterns were observed in 9 (11.11%), 50 (61.73%) and 22 (27.16%) tumours, respectively. Tumour recurrence rates and tumour-related deaths were not associated with KIT staining patterns (P = 0278, P > 0.05), KIT (P = 0.289, P > 0.05) or KIT ligand (P = 0.106, P > 0.05) gene expression. Despite the lack of association between KIT staining pattern and patient survival time, the results suggest a correlation between aberrant KIT localization and increased proliferative activity of MCTs. RT-PCR seems to be a sensible method for quantitative detection of KIT gene expression in canine MCT, although expressions levels are not correlated with prognosis.

E-cadherin in canine mast cell tumors: decreased expression and altered subcellular localization in Grade 3 tumors

Mast cell tumors (MCTs) are the most frequent round cell tumors in dogs and comprise approximately 21% of all canine cutaneous tumors. MCTs are highly invasive and metastatic corresponding to the histological grade. E-cadherin is an adhesion molecule expressed in epithelial cells and although it is an epithelial cellular marker, studies have shown expression of E-cadherin in canine round cell tumors. To better characterize the expression pattern of E-cadherin in several different histological grades of MCTs in dogs, the expression and localization of the adhesion molecule was investigated using immunohistochemistry. For this purpose, 18 cutaneous MCTs were classified into three histological grades, 1, 2 or 3. Clinical history and follow-up data were available for all of the dogs. Cytoplasmic and nuclear expressions of E-cadherin in all three types of tumors were verified by immunostaining using two different antibodies. There was decreased E-cadherin expression in the more aggressive MCTs (Grade 3), suggesting an association between E-cadherin and tumor aggressiveness. Additionally, the loss of E-cadherin expression in either the cytoplasm or nucleus in more aggressive and undifferentiated tumor types confirmed the importance of cellular adhesion in tumor behavior.

Retrospective--systematic study and quantitative analysis of cellular proliferation and apoptosis in normal, hyperplastic and neoplastic perianal glands in dogs

Neoplasms in the perianal region are frequently diagnosed in dogs. The aetiology is unknown, and most of them are benign. In this study, 240 neoplasms of the perianal glands of dogs were retrieved from the Department of Pathology archives of the Faculty of Veterinary Medicine and Zootechny of University of São Paulo (FMVZ/USP), from 1984 to 2004. All 240 cases were re-examined by two pathologists. Nine cases (4%) were diagnosed as hyperplasia, 49 (20%) as group I adenoma, 81 (34%) were classified as moderately differentiated adenomas of the group II, 46 (19%) were poorly differentiated adenomas of group II, 48 (20%) were carcinoma of the group III according to the classification proposed by Berrocal, and 7 (13%) were other kind of tumours. Males over 8 years of age were predominantly affected. Cell proliferation was quantified by counting proliferating cell nuclear antigen (PCNA) positive nuclei, and apoptosis was quantified by counting fluorescent eosin-stained apoptotic corpuscles (AC) in normal tissue, hyperplasia and in different histologic types of neoplasia of these glands. A parallel pattern of increase in both parameters (cell proliferation and apoptosis) was obtained. The net growth index (NGI), represents how much a cell population is proliferating or dying and was achieved by dividing the mean PCNA count in 1000 cells by the mean AC stain count in 1000 cells. NGI was different between hyperplasia and neoplasia; group I adenomas have a much higher potential of growth, and NGI decreases from benign towards malignant lesions. These results show up the importance of studying cell proliferation and apoptosis to understand the carcinogenesis of dog perianal gland.

New Alternative Methods to Teach Surgical Techniques for Veterinary Medicine Students despite the Absence of Living Animals. Is that an Academic Paradox?

Due to a raised ethical mentality, veterinary schools are pursuing methods to preserve animal corpses used for surgical technique classes in an attempt to reduce the use of living animals for teaching. Generally speaking, animal and human bodies are usually preserved with 10% aqueous formalin solution especially for descriptive anatomy classes. Other possibilities include the use of glycerol, alcohol and phenol. At present, new fixatives have been developed to allow a better and longer preservation of animal corpses in order to maintain organoleptic characteristics, i.e. colour, texture, as close as possible to what students will deal with living animals. From 2004, in our college, surgical technique classes no longer use living animals for students' training. Instead, canine corpses chemically preserved with modified Larssen (MLS) and Laskowski (LS) solutions are preferred. The purpose of this study was to investigate comparatively the biological quality of preservation of these two solutions and to evaluate students' learning and acceptance of this new teaching method. Although these fixatives maintain body flexibility, LS solution failed to keep an ordinary tissue colouration (cadavers were intensely red) and tissue preservation was not adequate. By contrast, MLS solution, however, did not alter the colouration of cadavers which was fairly similar to that normally found in living animals. A remarkable characteristic was a very strong and unpleasant sugary odour in LS-preserved animals and therefore the MLS solution was the elected method to preserve cadavers for surgical technique classes. The students' feedback to the use of Larssen-preserved cadavers was very satisfactory, i.e. 96.6% of students were in favour of the use of cadavers for surgical training and on average 91.8% (2002-2003) of students preferred the MLS solution as the chemical preserver, whereas only 8.2% elected LS solution for teaching purposes. From the students' point of view (95.1%) the ideal class would be an initial training in MLS cadavers followed by classes with animals admitted to the Veterinary Hospital.

Expression of connexins 26 and 43 in canine hyperplastic and neoplastic mammary glands

Gap junctions are the only communicating junctions found in animal tissues and are composed of proteins known as connexins. Alterations in connexin expression have been associated with oncogenesis; reported studies in rodent and human mammary glands, which normally express connexins 26 and 43, confirm these alterations in malignancies. Mammary neoplasms represent the second most frequent neoplasm in dogs, and since there are no reports on the study of connexins in canine mammary glands, the present study investigated the expression of connexins 26 and 43 in normal, hyperplastic, and neoplastic mammary glands of this species, to verify if altered patterns of connexin staining are related to higher cell proliferation and malignant phenotypes. A total of 4 normal, 8 hyperplastic mammary glands, 9 benign, and 51 malignant mammary gland neoplasms were submitted for the immunostaining of connexins 26 and 43, E-cadherin, and proliferating cell nuclear antigen (PCNA). Normal, hyperplastic, and benign neoplastic mammary glands showed a punctate pattern for connexin 26 and 43 staining and an intercellular E-cadherin staining. Malignant neoplasms, especially the most aggressive cases with high cell proliferation rates, presented either fewer gap junction spots on the cell membranes or increased cytoplasmic immunostaining. Malignant tumors also expressed a less intense immunostaining of E-cadherin; the expression of this adhesion molecule is important for the transportation of connexins to cell membranes and in forming communicating gap junctions. Deficient expression of E-cadherin could be related to the aberrant connexin localization and may contribute to the malignant phenotype. In conclusion, the expression and distribution of connexins and E-cadherin are inversely correlated to cell proliferation in malignant mammary neoplasms of dogs and may well be related to their more aggressive histologic type and biologic behavior.

Ureterotomia como tratamento de obstrução ureteral em dois cães

O artigo não apresenta resumo.

Uso de pino intramedular na reparação de fraturas de ossos longos em psitacídeos: arara-azul (Anodorhynchus hyacinthinus), arara-canindé (Ara ararauna) e papagaio-verdadeiro (Amazona aestiva)

O artigo não apresenta resumo.

Aspectos ultra-sonográficas modo B, Doppler colorido e Power doppler no carcinoma de células transicionais da bexiga de cães. Estudo de casos

O artigo não apresenta resumo.

Ressecção parcial e omentalização de cisto prostático de retenção em três cães

O artigo não apresenta resumo.

Nonaspiration fine needle cytology and its histologic correlation in canine skin and soft tissue tumors

OBJECTIVE

To analyze the findings of nonaspiration fine needle (NAFN) cytology as compared with the histopathologic findings in evaluating canine skin and soft tissue tumors.

STUDY DESIGN

NAFN (21-27 gauge) cytology was performed on 213 cases. Smears were air dried and stained by the Rosenfeld method (May-Grünwald-Giemsa modification). Histopathologic evaluation was available for comparison in 40% of cases.

RESULTS

NAFN cytology and histopathology results were compared in 85 dogs. The size of the 117 lesions varied from 0.5 to 2 cm (n=39), 2.1 to 5 cm (n=43), and > or = 5.1 (n=35). There were 22 nonneoplastic lesions, mostly inflammatory processes and cysts. Neoplastic lesions were classified as epithelial (36%), mesenchymal (30%), round cell tumor (n=13) and melanocytic (2%). Among 40 malignant lesions, mast cell tumor (n=14) and hemangiopericytoma (n=9) were the most frequent. Lipoma (n=14) and trichoblastoma (n=10) were the most common benign neoplastic lesions. Cytology showed sensitivity of 89%, specificity of 100%, positive and negative predictive value of 100% and 96%, respectively, and efficacy of 97%.

CONCLUSION

NAFN cytology is extremely useful and accurate. It is safe and avoids the use of anesthesia. Further, it is easy to perform and noninvasive and usually provides a high-quality sample.