M.J. García-Iglesias

Spontaneous mouse mammary tumours: incidence and cytokeratin expression.

The purpose of this study was to advance our knowledge of the histogenesis of spontaneous mammary tumours in laboratory mice. Normal mammary tissue and 19 spontaneous mammary tumours from adult female mice were examined using monoclonal and polyclonal antibodies differing in their recognition of various cytokeratin intermediate filament proteins (CKs). All neoplasms were intraductal and were invasive carcinomas with a tubular, papillary, cystic or solid growth pattern. CK8-positive reactions were detected in the normal alveolar and ductal epithelia and CK5- and CK14-positive reactions were seen in myoepithelial cells of nonlactating mammary glands. Positive staining for CK5 and CK8 was detected in all tumours and CK14 was expressed in those with a papillary pattern. Comparisons between non-lactating glands and tumours indicated that the neoplasms were well or moderately differentiated, there was no squamoid differentiation and that they arose from the alveoli and duct system, not the myoepithelial cells.

A vaccine based on a mutant transferrin binding protein B of Haemophilus parasuis induces a strong T-helper 2 response and bacterial clearance after experimental infection.

This study aimed to characterize the type of immune response induced by an experimental vaccine based on a mutant Haemophilus parasuis transferrin binding protein (Tbp) B (Y167A) defective in its ability to bind porcine transferrin. Clinical and pathological signs, bacterial clearance, antibody response and the cytokine profile in alveolar macrophages and spleen after the vaccination and challenge of twenty-two colostrum-deprived pigs with 10(8) CFU of H. parasuis were analysed. Pigs vaccinated with Y167A were compared to those vaccinated with native TbpB (nTbpB), those treated with a commercial bacterin (CB) against Glässers disease, those unvaccinated challenged (CH) and those unvaccinated unchallenged (UNCH) pigs. The rectal temperatures of Y167A pigs resembled those of UNCH pigs and were significantly lower than those of the nTbpB, CB and CH animals. A major reduction in pathological changes of the challenged pigs was observed in the Y167A group. H. parasuis was cleared from 88.9% of the samples from Y167A pigs versus 60.0% and 55.6% from those of the CB and nTbpB groups, respectively. The antibody response elicited by Y167A by ELISA was notably higher than that observed for nTbpB and CB pigs and was capable of preventing the expression and secretion of IL-8. The expression of IL-4 and IL-5, which were associated with the specific antibody levels, suggests that the main mechanism of protection conferred by Y167A vaccine is based on a strong T-helper 2 response.

Optimization of the immunohistochemical demonstration of keratins in paraffin wax-embedded mouse skin.

The purpose of this study was to develop an immunoperoxidase technique for the detection of cytokeratins in samples of paraffin wax-embedded adult and fetal skin from NMRI mice, with various antibodies (Troma-1, LL001, 8.60, MCK5, MCK6, AF129) that have been tested mainly on fresh-frozen sections. Each antibody was tested with three different fixatives (10% neutral buffered formalin, Bouins fluid, and 70% ethanol) and two distinct pretreatments (enzymatic digestion with trypsin, or heat treatment). The best results, in terms of non-specific background labelling, morphological preservation and intensity of specific labelling, were obtained (1) for adult skin, by the use of Bouins fluid, heat pretreatment and antibodies LL001, MCK5, MCK6 or AF129, and (2) for fetal skin, by the use of 70% ethanol, heat pretreatment and antibody Troma-1. Monoclonal antibody 8.60 gave the best results when the use of 70% ethanol was combined with either enzymatic digestion or heat pretreatment.

A pathological study of experimental long-standing Schistosoma bovis infection in sheep

The pathological response of sheep to two dose levels (400 or 10,000 cercariae) of Schistosoma bovis was evaluated 24 weeks after infection. The results confirmed that a single low or high dose causes lesions in the liver and intestine, and that the lungs, lymph nodes, pancreas and abomasum are affected in sheep given a single high dose. In addition, the study showed that pathological changes (mainly a granulomatous inflammatory reaction) were induced not only by eggs but also by adult worms, and that their severity was in general related to the dose of S. bovis. Hoeppli reaction product, observed on the surface of adult schistosomes in some parasitic granulomas, showed no immunoreaction for IgG, IgA or IgM.

Recurrent Outbreaks of Myelodysplasia in Newborn Calves

The present study records recurrent outbreaks of myelodysplasia of unknown origin occurring in a specific geographical location in the north of Spain, and involving up to 30% of the calves born in affected herds. The affected calves were of different breeds and displayed non-progressive signs of spinal cord dysfunction. The disease has occurred annually in February-March over a period of at least 15 years. Only calves born to cattle grazed on mountainside pastures and under high grazing pressure were affected. Seven calves were subjected to necropsy examination. Myelodysplasia was not associated with vertebral defects or arthrogryposis and involved the entire length of the spinal cord. Microscopically, there was abnormal distribution of the grey matter, aberrations of the central canal and failure of formation of the ventral median fissure. Infectious, nutritional and physical disorders were ruled out as possible aetiologies. A critical period of embryonic susceptibility to the causal agent was identified. This was during the time of secondary neurulation when cows in the early stages of gestation were grazed on mountainside pastures. Consequently, the presence of neuroteratogenic plants in these pastures is proposed as a likely cause. Two plants, Carex brevicollis and Erythronium dens-canis, which contain alkaloids, were identified on the mountainsides where affected cattle were grazed and not in other pastures, and are proposed as the possible aetiology of the disease.

Lymphoid leukosis in an ostrich (Struthio camelus).

Red blood cell count (xlOi2/litre)** 7-2 (1.4) Haemoglobin concentration (g/litre)** 95-1 (13-2) Haematocrit value (litre/litre)** 0-328 (0-044) MCV (fl) 47-9 (10-4) MCH (pg) 13-6 (2-2) MCHC (g/litre)* 287.2 (17-1) White blood cell count (xlO9/litre) 15.1 (8-4) Platelet count (xl09/litre) 440-6 (234-2) Lymphocytes (0) 37-0 (24-3) Monocytes (%) 3-1 (3-5) Segmented neutrophils (0) 55-6 (24-2) Band neutrophils (0) 2-5 (3-3) Eosinophils (%) 1-4 (2-6) Basophils (%) 0-1 (0-6) Gastric ulceration (n=21)

Immunogenic characterization of vaccines based on Haemophilus parasuis Nagasaki strain, OmpP2, OmpP5 and OmpD15, in colostrum-deprived pigs experimentally challenged with the same strain

Three recombinant outer membrane proteins (rOmps) from the Haemophilus parasuis Nagasaki strain (serovar 5 reference strain), rOmpP2, rOmpP5 and rOmpD15, which have previously shown protection against H. parasuis infection in mice, were cloned, expressed and evaluated as vaccine antigens in colostrum-deprived pigs. When these animals were immunized with these rOmps and were later challenged intratracheally with 108 CFUs of the Nagasaki strain, no protection was seen in terms of survival, clinical signs, pathological results and recovery of H. parasuis. We hypothesized that a possible explanation for this lack of protection could be the low number of epitopes accessible to the immune system as a consequence of their poor exposure on the bacterial surface so that the immune response would not be able to protect against experimental infection by H. parasuis when a fully susceptible animal model, such as pigs, was used.