Enzyme activities in some types of peripheral leukocytes of thoroughbred race horses before and after the races

Glucose, free fatty acid (FFA), triglyceride (TG) and immunoreactive insulin (IRI) concentrations in plasma and activities of enzymes related to energy metabolism in some types of peripheral leukocytes were measured in thoroughbred race horses before and after racing. Glucose, FFA, TG and IRI concentrations and enzyme activities did not change significantly in plasma. However, the activities of cytosolic hexokinase, malate dehydrogenase (MDH), mitochondrial MDH and aspartate aminotransferase decreased significantly in leukocytes of the horses after the races. The cytosolic ratio of MDH/LDH activity (ML ratio) in leukocytes decreased significantly after racing, and the ratio may be a useful indicator to evaluate energy metabolism in race horses.     

Identification of the Cryptosporidium isolate from chickens in Japan by sequence analyses

The Cryptsosporidium isolate from chickens in Japan by Itakura et al. is not yet accurately identified because of several discrepancies in phenotypic features. We attempted to identify this isolate by analyzing the partial sequences of the 18S rRNA, COWP and HSP70 genes. The chicken isolate showed nearly 100% homology in each gene with C. baileyi, but less than 91% homology with C. meleagridis. In addition, these genes were classified into the same cluster with C. baileyi other than C. meleagridis by phylogenetic analysis. From these results, the Cryptosporidium isolate from chickens in Japan is considered to be one of the strains of C. baileyi.     

Innate immune response to intramammary infection with Serratia marcescens and Streptococcus uberis

Streptococcus uberis and Serratia marcescens are Gram-positive and Gram-negative bacteria, respectively, that induce clinical mastitis. Once initial host barrier systems have been breached by these pathogens, the innate immune system provides the next level of defense against these infectious agents. The innate immune response is characterized by the induction of pro-inflammatory cytokines, as well as increases in other accessory proteins that facilitate host recognition and elimination of the pathogens. The objective of the current study was to characterize the innate immune response during clinical mastitis elicited by these two important, yet less well-studied, Gram-positive and Gram-negative organisms. The pro-inflammatory cytokine response and changes in the levels of the innate immune accessory recognition proteins, soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), were studied. Decreased milk output, induction of a febrile response, and increased acute phase synthesis of LBP were all characteristic of the systemic response to intramammary infection with either organism. Infection with either bacteria similarly resulted in increased milk levels of IL-1 beta, IL-8, IL-10, IL-12, IFN-gamma, TNF-alpha, sCD14, LBP, and the complement component, C5a. However, the duration of and/or maximal changes in the increased levels of these inflammatory markers were significantly different for several of the inflammatory parameters assayed. In particular, S. uberis infection was characterized by the sustained elevation of higher milk levels of IL-1 beta, IL-10, IL-12, IFN-gamma, and C5a, relative to S. marcescens infection. Together, these data demonstrate the variability of the innate immune response to two distinct mastitis pathogens.     

Protective effect of Pasteurella multocida cell-free antigen and toxoid against challenge with toxigenic strains of pasteurella multocida in mice

The cell-free antigen (CFA) obtained from the culture supernatant of Pasteurella multocida (P. multocida) and the toxin (PMT) purified from CFA were inactivated and mixed with oil adjuvant to prepare a trial vaccine. Both of the mice immunized with CFA and PMT toxoid vaccine were noticeably protected against intratracheal challenge with toxigenic strains of P. multocida. Nevertheless, the protective indices of the mice immunized with CFA vaccine indicate that it is more protective and clears away the bacteria more promptly than in the mice immunized with PMT vaccine. The results suggested that CFA would possibly be good as an effective antigen to toxigenic strains of P. multocida infection.     

Penetration of drug resistance in Escherichia coli isolated from laboratory animals

A total of 713 strains of fecal Escherichia coli (E. coli) isolated from laboratory animals in the colonies of 4 research laboratories and 4 commercial breeders in Japan in 1994 were examined in regard to resistance to 8 antibacterial agents. The incidence of resistance to sulfadimethoxine (Su), streptomycin (Sm), ampicillin, cephaloridine, tetracycline, chloramphenicol, kanamycin, and gentamicin was 99.9%, 32.5%, 6.7%, 0.7%, 7.0%, 2.6%, 6.6% and 0.7%, respectively. These results indicated that Su and Sm resistance are penetrating into normal E. coli strains isolated from laboratory animals.     

Vascular endothelial growth factor (VEGF) promotes the early development of bovine embryo in the presence of cumulus cells

Three experiments were conducted to determine the effect of Vascular Endothelial Growth Factor (VEGF) on bovine embryonic development in vitro. Human recombinant VEGF(165) was employed at 5 ng/ml in modified synthetic oviduct fluid. In Exp. 1, bovine cumulus oocyte complexes were matured with or without VEGF for 22 hr, inseminated without VEGF for 6 hr, then cultured with or without VEGF for 42 hr. The cleavage rate and the development rate to 4- to 8-cell were higher (P<0.05) in groups with VEGF during in vitro maturation (IVM, 71.4% and 59.6%), in vitro culture (IVC, 70.3% and 62.3%), and both IVM and IVC (75.9% and 67.8%) than in the group cultured thoroughly without VEGF (49.9% and 38.4%, respectively). In Exp. 2, 4- to 8-cell embryos produced in vitro without VEGF were removed from cumulus cells at 48 hr post-insemination (Pi) and cultured with or without VEGF for 144 hr. The development rates to blastocyst at 96 hr (D6), 120 hr (D7) and 144 hr (D8) were similar (P>0.05) in both groups. In Exp. 3, cumulus cells were removed from presumptive embryos produced by IVM and IVF without VEGF at 10 hr Pi. Denuded embryos were cultured with or without VEGF for 38 hr or 182 hr. The cleavage rate and the development rates to 4- to 8-cell at 48 hr Pi and to blastocyst on D6, D7 and D8 were similar (P>0.05) in all groups. These results suggest that VEGF has a beneficial effect on the initial development of bovine embryo through surrounding cumulus cells.     

Brain lesions and transmission of experimental equine herpesvirus type 9 in pigs

We demonstrated that pigs are susceptible to acute infection by equine herpesvirus type 9 (EHV-9). Six 8-week-old SPF pigs were inoculated intranasally and four were inoculated orally with different doses of EHV-9, and observed for 6 days. Although neurological signs did not develop in any of the infected pigs, the six intranasally infected pigs and one of the orally infected pigs developed lesions of encephalitis consisting of neuronal necrosis, neuronophagia, and intranuclear inclusion bodies, distributed mainly in the rhinencephalon. EHV-9 antigen was localized in the necrotic neuronal cells and was closely associated with the presence of inclusion bodies. These findings clearly demonstrate that pigs are fully susceptible to EHV-9 infection following intranasal inoculation (but less so following oral inoculation), and that EHV-9 in pigs has a highly neurotropic nature.     

Comparative immunohistopathology in pigs infected with highly virulent or less virulent strains of hog cholera virus

Eight pigs were inoculated subcutaneously with a highly virulent hog cholera virus (HCV) strain ALD. The infected pigs developed severe illness and became moribund on postinoculation day (PID) 7 or PID 10. Histologic lesions were characterized by severe generalized vasculitis, necrosis of lymphocytes, and encephalitis. HCV antigen was detected in crypt tonsilar epithelial cells, macrophages, and reticular endothelial cells of lymphoid tissues. Antigen localization corresponded well with histologic lesions. Five pigs were inoculated with less virulent HCV Kanagawa/74 strain and were euthanatized on PID 30. All five infected pigs recovered from the illness but became stunted. They also had a slight follicular depletion of lymphocytes, histiocytic hyperplasia, and hematopoiesis in the spleen. Less virulent HCV antigen was observed in the tonsils, kidneys, pancreas, adrenal glands, and lungs. Although antigen localization was less associated with histologic lesions, immunoreactivity was stronger than that in the pigs infected with the ALD strain of HCV. An almost complete loss of B lymphocytes was recognized in pigs infected with the ALD strain and was correlated with follicular necrosis in lymphoid tissues. Loss of B lymphocytes was not prominent in the pigs infected with Kanagawa/74 strain. The number of CD4+ and CD8+ T lymphocytes was significantly higher than that in the noninfected control pigs.