The in vitro growth of erythroid colonies from dog bone marrow.

Enriched methyl cellulose media together with either human urinary erythropoietin or serum collected from phlebotomized dogs exposed to hypoxia was used in the study of the erythroid colony forming (CFU-E) capacity of dog marrow. The dog serum erythropoietin was found to be more efficient in stimulating CFU-E than comparable concentrations of human urinary erythropoietin. Numbers of CFU-E were directly related to the culture concentration of the stimulating serum and to the number of cells per plate. Sheep plasma erythropoietin was also found to be effective in stimulating CFU-E growth. The system described is chemically better defined and produced more consistent results than has been reported for the plasma clot method.     

Susceptibility of sheep to European bat lyssavirus type-1 and -2 infection: a clinical pathogenesis study

European bat lyssaviruses (EBLVs) have been known to cross the species barrier from their native bat host to other terrestrial mammals. In this study, we have confirmed EBLV-1 and EBLV-2 susceptibility in sheep (Ovis ammon) following intracranial and peripheral (intramuscular) inoculation. Notably, mild clinical disease was observed in those exposed to virus via the intramuscular route. Following the intramuscular challenge, 75% of the animals infected with EBLV-1 and 100% of those that were challenged with EBLV-2 developed clinical signs of rabies and then recovered during the 94-day observation period. Disease pathogenesis also varied substantially between the two viruses. Infection with EBLV-1 resulted in peracute clinical signs, which are suggestive of motor neuron involvement. Antibody induction was observed and substantial inflammatrory infiltrate in the brain. In contrast, more antigen was detected in the EBLV-2-infected sheep brains but less inflammatory infiltrate and no virus neutralising antibody was evident. The latter involved a more protracted disease that was behaviour orientated. A high infectious dose was required to establish EBLV infection under experimental conditions (> or =5.0 logs/ml) but the infectious dose in field cases remains unknown. These data confirm that sheep are susceptible to infection with EBLV but that there is variability in pathogenesis including neuroinvasiveness that varies with the route of infection. This study suggests that inter-species animal-to-animal transmission of a bat variant of rabies virus to a terrestrial mammal host may be limited, and may not always result in fatal encephalitis.     

Enzyme changes in neurons and glia during barbiturate sleep

During barbiturate sleep of rabbits, the succinoxidase activity in isolated neurons and glia from the caudal part of the reticular formation was lower than that during physiological sleep. No rhythmical, inverse enzyme changes were detected in barbiturate sleep in the neuron-glia unit, such as were found in physiological sleep.     

Dietary non-starch polysaccharides alter the abundance of pathogenic clostridia in pigs

Some non-starch polysaccharides (NSP) promote the intestinal abundance of pathogenic Escherichia coli in pigs. However, their impact on pathogenic clostridia in the porcine intestinal tract is unknown. The present study aimed to determine the abundance of pathogens belonging to Clostridium clusters I and XI in faeces of growing pigs fed four semi-purified diets containing 5% of purified NSP differing in viscosity and fermentability (low-fermentable low-viscous cellulose; low-fermentable high-viscous carboxymethylcellulose; high-fermentable low-viscous oat β-glucan; and high-fermentable high-viscous oat β-glucan). For quantification of clostridial pathogens, toxin genes were determined using quantitative PCR. Clostridium perfringens α-toxin was detected in faeces of pigs fed low-fermentable cellulose and carboxymethylcellulose diets but was generally below detection limit for the two high-fermentable oat β-glucans. Clostridium botulinum toxin C2 was higher (P<0.05) by 0.7 to 0.9 log units in faeces of pigs fed the low-fermentable low-viscous cellulose diet than of pigs fed the other three diets. Clostridium difficile toxin B and Clostridium sordellii phospholipase C were not detected in pig faeces indicating that pigs were not colonized by these clostridial species belonging to Clostridium cluster XI. In conclusion, high-fermentable β-glucans decreased the faecal abundance of C. perfringens and, together with low-fermentable high-viscous CMC, that of C. botulinum in growing pigs when compared to low-fermentable low-viscous CEL. Besides fermentability, structural characteristics and indirect effects of NSP on nutrient flow into the large intestine may have played a role for the abundance of pathogenic clostridial species.