Julio Roberto Idiart

Lack of prognostic significance of angiogenesis in canine melanocytic tumours.

The prognostic significance of angiogenesis in some canine tumours has been investigated, but little is known about its relevance in canine melanocytic tumours (MTs). The aim of this study was to evaluate the prognostic significance of angiogenesis in canine MTs. A total of 36 cutaneous melanocytomas (benign MTs), 40 cutaneous melanomas (malignant MTs) and 43 oral melanomas were studied. Survival data were available for a subset of 59 cases. Microvessel density (MVD) and endothelial area (EA) were determined by immunolabelling using an antibody specific for von Willebrand factor (vWF). Mean MVD (expressed as the number of microvessels per mm(2)) was 129 ± 14 in melanocytomas, 191 ± 16 in cutaneous melanomas and 208 ± 16 in oral melanomas. Mean EA (expressed as the percentage of the total area) was 1.5 ± 0.14 in melanocytomas, 2.6 ± 0.2 in cutaneous melanomas and 2.4 ± 0.3 in oral melanomas. The differences in MVD and EA between melanocytomas and melanomas were significant (P = 0.001 and P = 0.003, respectively). MVD and EA were significantly correlated between cutaneous and oral MTs (r = 0.54; P <0.001 and r = 0.63; P <0.001, respectively). MVD and EA were not related to survival in cutaneous and oral MTs. In conclusion, tumour vascularization was higher in melanomas than in melanocytomas, but it seemed to have no prognostic significance in these tumours.

Fibrinonecrotic enteritis of piglets in a commercial farm: a postmortem study of the prevalence and the role of lesion associated agents Isospora suis and Clostridium perfringens

The objectives were to determine the prevalence of fibrinonecrotic enteritis (FNE) on a farrow-to-finish farm of 1,000 sows, to categorize the pathological changes, and to to investigate the lesion associated agents Isospora suis and Clostridium perfringens. Causes of preweaning mortality (PWM) were classified into 8 categories including FNE. Obtained data were evaluated for statistical significance by adjusted Chi-square analysis. Samples of FNE were taken for complementary studies including a PCR technique for genotyping toxin genes of Clostridium perfringens from gut samples fixed in 10% neutral formalin. From 3,153 piglets examined, less than 1% was classified as FNE. FNE prevalence increased progressively from the first to the third week, the last differing statistically from the others. Eighty percent of gut samples with FNE lesions were positive to Isospora suis, when examined by PCR from 9 severe FNE lesions detected 7 positive samples only for a toxin gene, characteristic of C. perfringens type-A.

Canine mammary carcinomas: influence of histological grade, vascular invasion, proliferation, microvessel density and VEGFR2 expression on lymph node status and survival time

Spontaneous invasive non-inflammatory canine mammary carcinomas (CMC) and their regional lymph nodes (LN) were analysed (n = 136). Histological grade (HG) and vascular invasion (VI) in the tumours and lymph node status were recorded. Proliferation index (PI), microvessel density (MVD) and vascular endothelial growth factor receptor 2 (VEGFR2) expression were estimated using anti-proliferating cell nuclear antigen (PCNA), anti-von Willebrand factor and anti-Flk-1, respectively. Eighteen months follow-up was performed (34 bitches). Tumours of different grades showed differences regarding PI, Flk-1/integrated optical density (Flk-1/IOD) and MVD. Every feature showed significant association with LN status through bivariate analyses. From multivariate analyses, VI and Flk-1/IOD were selected to predict LN status. Data revealed that the probability of a CMC-bearing bitch to remain alive at 1, 4, 5 and 14-18 months was 0.91, 0.87, 0.81 and 0.77, respectively. Besides LN status, VI was the only feature positively correlated with survival time, although a trend to shorter survival of animal patients bearing high expressing VEGFR2 CMC was noted.

CARACTERÍSTICAS MACRO Y MICROSCÓPICAS DEL CORAZÓN Y GRANDES VASOS DEL COIPO (Myocastor coypus, Molina) DE DIFERENTES EDADES

Se realizo un estudio sobre las caracteristicas macro y microscopicas del corazon y grandes vasos de coipos (Myocastor coypus, Molina) de diferentes edades. Asimismo, se estudiaron macroscopicamente las venas superficiales, de probable aplicacion en la venopuncion. Se utilizaron 44 animales de ambos sexos, incluyendo adultos, prepuberes, recien nacidos y fetos de 120 dias de gestacion. El corazon y los grandes vasos de 18 animales adultos y prepuberes y de 14 recien nacidos, asi como las venas cefalica y safenas lateral y medial de los adultos y prepuberes, fueron disecados, medidos y fotografiados. Tambien se tomaron muestras de corazon y aorta de animales de todas las edades, las que se fijaron y procesaron histologicamente con los metodos clasicos, para luego colorearlas con hematoxilina y eosina, picrosirius-red , hematoxilina ferrica de Verhoeff y resorcina-fucsina de Weigert, con y sin oxidacion previa con oxona. Los resultados obtenidos indican que el corazon y los grandes vasos son, en general, similares al de otros roedores, aunque con algunas caracteristicas propias. El peso relativo del corazon oscilo entre 0,93 % y 1,03 %. Las venas mas apropiadas para la venopuncion resultaron ser la cefalica y la safena lateral. El sistema de fibras resulto similar en los adultos y prepuberes a otros roedores. En los fetos, cuando fueron comparados con los recien nacidos, se constataron diferencias de cantidad y de distribucion, sobre todo en las fibras del sistema elastico

ESTUDIOS MACRO Y MICROSCOPICO DEL SACO ANAL DEL COIPO (Myocastor coypus)

RESUMEN:Fue realizada la diseccion del saco anal de 44 coipos, de ambos sexos, de distintas edades y procedencias, observandose algunas caracteristicas similares a los sacos anales del perro y gato, aunque es impar y esta ubicado en ventral del ano. Es ovoideo o piriforme, siendo mas grande en los adultos y, entre estos, mas aun en los machos que en las hembras; posee un conducto que desemboca en el canal anal a un centimetro del ano y que se exterioriza en el momento de secretar el producto glandular. Se encuentra rodeado de una capsula de tejido fibroso e insertado en ella se observa tejido muscular estriado, correspondiente a fibras de los musculos del diafragma pelviano. Microscopicamente esta constituido por un tejido glandular tubuloalveolar, con celulas globosas de nucleo laxo, con uno o mas nucleolos. Desde la capsula hacia el interior se forman tabiques de tejido conectivo que dividen al tejido glandular en lobulos y lobulillos. Mediante coloraciones especiales se constato la presencia de fibras que contienen colageno de los tipos I y III, de fibras eleuninicas y oxitalanicas.