Porcine proliferative enteropathy in Estonian pig herds: histopathology and detection of Lawsonia intracellularis by PCR.

Lawsonia intracellularis is the causative agent of proliferative enteritis in pigs (PPE). This bacterium is difficult to culture from clinical samples and antemortem demonstration is therefore usually performed by PCR on faecal samples. The aim of this study was to elucidate the frequency of L. intracellularis infection in pig herds in Estonia using PCR, histopathological methods and electronmicroscopical studies. The frequency of demonstration of L. intracellularis was highest in 9-12 weeks old pigs (68.1%). It was more frequent in growing pigs with enteritis on small farms where the system of "all-in all-out" was not practiced and where standards of hygiene were poor. Gross and histopathological studies demonstrated that characteristic macroscopic changes associated with PPE were localised to the distal jejunum and ileum.Thickened longitudinal and circumferential folds occurred in the mucosa of the affected regions of the bowel. Samples from pigs aged 4 to 20 weeks exhibited the most intensive inflammatory changes. The distal part of the jejunum, ileum and the upper third of proximal colon and cecum wall were visibly thickened with reduced luminal diameter. Hyperplasia of lymphoid tissue and, in many cases, pseudomembranous or fibrinous inflammation was found. L. intracellularis was detected in 56 young pigs using histopathological methods. Additionally, in 8 of these pigs intracellular bacteria were demonstrated in ilial epithelial cells by transmission electronmicroscopical (TEM) investigation. On the basis of these TEM investigations it was concluded that L. intracellularis causes disturbances of normal growth, differentiation and apoptosis of the epithelial cells of ileum.

Effect of cyclic 3', 5' adenosin-monophosphate on osteogenesis embryonic bone cultivated in tissue culture: an autoradiographic study.

UNLABELLED: The aim of this study was to evaluate the effect of cyclic 3', 5' adenosin-monophosphate (cAMP) on DNA synthesis of embryonic alveolar bone in tissue culture. MATERIAL AND METHODS: Bone fragments were cultured in the medium composed of 80% medium 199, 15% horse serum, 4 mg/ml glucose, 100 microg/ml penicillin using the grid method. The explants were cultured up to 12 days. In the second series, the effect of cAMP in a concentration of 10(-6)M on bone during 12 days was studied. DNA synthesis was determined by calculating mitotic labelling indices for (3)H-thymidine incorporation into cells within cultured explants at 3 to 12 days. The medium was supplemented with 1 microCurie/ml (3)H-thymidine for 4 hours and processed for autoradiography. The mitotic labelling index was determined in the histological sections. All values wer presented as mean+/-standard deviation. Statistical significance was defined by p-values of 0.05 or less. RESULTS: Morphological and statistical analysis showed that there were differences in mitotic incidence (MI) and silver grain densities over osteoblasts in control cultures and with cAMP. The mean value of MI was 4,627+/-1,001 in control and 7,706+/-1,188 in the cultures where cAMP was added (p<0.05). CONCLUSION: Thus cAMP inhibited bone resorption and stimulated new bone formation in tissue culture. This study provides a novel concept that may help to identify new therapeutic targets.