Oral A. Evanson

Gastric digestion in some raptors

Abstract 1. 1. Gastric digestion of mice in falconiforms is apparently more thorough than it is in strigiforms because the proportion of the food consumed that reappears as a pellet is lower in the former than in the latter. 2. 2. This difference is principally due to a more thorough corrosion of the bones in the food by Falconiformes, i.e. there is a smaller proportion of bone in falconiform pellets. 3. 3. Falconiform gastric juice contains considerably more hydrogen ion than strigiform and this probably accounts for the greater bone corrosion by falconiforms. 4. 4. Gastric proteolytic activity is about equal before and after eating in both orders of raptors. 5. 5. The meal-to-pellet interval is also about equal between the two orders. 6. 6. The pH and proteolytic activity of the gastric juice of raptors were in general significantly bifferent from these values in domestic ducks and turkeys, but the values found for poultry agree with published data.

Differential Responses of Bovine Macrophages to Mycobacterium avium subsp. paratuberculosis and Mycobacterium avium subsp. avium

ABSTRACT Mycobacterium avium subsp. paratuberculosis and Mycobacterium avium subsp. avium are antigenically and genetically similar organisms; however, they differ in their virulence for cattle. M. avium subsp. paratuberculosis causes a chronic intestinal infection leading to a chronic wasting disease termed paratuberculosis or Johnes disease, whereas M. avium subsp. avium causes only a transient infection. We compared the response of bovine monocyte-derived macrophages to ingestion of M. avium subsp. paratuberculosis and M. avium subsp. avium organisms by determining organism survival, superoxide and nitric oxide production, and expression of the cytokines tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), interleukin-8 (IL-8), IL-10, IL-12, and granulocyte-monocyte colony-stimulating factor (GM-CSF). Unlike M. avium subsp. paratuberculosis, macrophages were able to kill approximately half of the M. avium subsp. avium organisms after 96 h of incubation. This difference in killing efficiency was not related to differences in nitric oxide or superoxide production. Compared to macrophages activated with IFN-γ and lipopolysaccharide, macrophages incubated with M. avium subsp. paratuberculosis showed greater expression of IL-10 and GM-CSF (all time points) and IL-8 (72 h) and less expression of IL-12 (72 h), IFN-γ (6 h), and TNF-α (6 h). When cytokine expression by macrophages incubated with M. avium subsp. paratuberculosis was compared to those of macrophages incubated with M. avium subsp. avium, M. avium subsp. paratuberculosis-infected cells showed greater expression of IL-10 (6 and 24 h) and less expression of TNF-α (6 h). Therefore, the combination of inherent resistance to intracellular degradation and suppression of macrophage activation through oversecretion of IL-10 may contribute to the virulence of M. avium subsp. paratuberculosis in cattle.

Meal to pellet intervals in 14 species of captive raptors.

Abstract 1. In owls, meal to pellet interval was directly related to meal weight and owls normally cast 1 pellet per meal; egestion of pellets in hawks apparently was associated with “lights-on” in the holding rooms regardless of quantity eaten and hawks normally egested less than 1 pellet per meal. 2. All of the smallest raptors digested meals and egested pellets more rapidly than the larger raptors. 3. The correlation between meal weight and pellet weight was only slightly better for owls than for hawks, but, because owl pellets contained more of the bones of their prey, they represented a greater proportion of the meal from which they originated.

Regulation of expression of major histocompatibility antigens by bovine macrophages infected with Mycobacterium avium subsp. paratuberculosis or Mycobacterium avium subsp. avium.

ABSTRACT Mycobacterium avium subsp. paratuberculosisand Mycobacterium avium subsp. avium are antigenically and genetically very similar organisms; however, they differ markedly in their virulence for cattle. We evaluated the capacity of bovine macrophages infected with M. aviumsubsp. paratuberculosis or M. avium subsp.avium to express major histocompatibility complex (MHC) class I and class II antigens on their surface and to interact with primed autologous lymphocytes. Our results indicate that infection of bovine macrophages with M. avium subsp.paratuberculosis promoted the downregulation of MHC class I and class II molecules on the macrophage surface within 24 and 12 h, respectively. Alternatively, MHC class II expression by M. avium subsp. avium-infected macrophages was not detected until 24 h after infection, and the magnitude of the decrease was smaller. Decreased MHC class I expression by M. avium subsp. avium-infected macrophages was not detected. Unlike M. avium subsp.paratuberculosis-infected macrophages, M. aviumsubsp. avium-infected macrophages upregulated MHC class I and class II expression after activation by gamma interferon or tumor necrosis factor alpha. Further, M. avium subsp.avium-infected macrophages were lysed by primed autologous lymphocytes, whereas M. avium subsp.paratuberculosis-infected macrophages were not. Overall, the results support the hypothesis that the difference in the virulence of M. avium subsp. paratuberculosis andM. avium subsp. avium for cattle is dependent on a difference in the capacity of the organisms to suppress mycobacterial antigen presentation to T lymphocytes.

Bovine monocyte TLR2 receptors differentially regulate the intracellular fate of Mycobacterium avium subsp. paratuberculosis and Mycobacterium avium subsp. avium.

Pathogenic mycobacterial organisms have the capacity to inhibit macrophage activation and phagosome maturation. Although the mechanism is complex, several studies have incriminated signaling through TLR2 receptors with subsequent activation of the MAPK pathway p38 (MAPKp38) and overproduction of IL‐10 in the survival of pathogenic mycobacterial organisms. In the present study, we compared the response of bovine monocytes with infection by Mycobacterium avium subspecies paratuberculosis (MAP), the cause of paratuberculosis in ruminants, with the closely related organism M. avium subspecies avium (Maa), which usually does not cause disease in ruminants. Both MAP and Maa induced phosphorylation of MAPKp38 by bovine monocytes; however, addition of a blocking anti‐TLR2 antibody partially prevented MAPKp38 phosphorylation of MAP‐infected monocytes but not Maa‐infected monocytes. Addition of anti‐TLR2 antibody enhanced phagosome acidification and phagosome‐lysosome fusion in MAP‐containing phagosomes and enabled monocytes to kill MAP organisms. These changes were not observed in Maa‐infected monocytes. The effect on phagosome maturation appears to occur independently from the previously described inhibitory effects of IL‐10 on phagosome acidification and organism killing, as IL‐10 production was not affected by addition of anti‐TLR2 antibody to monocyte cultures. Therefore, signaling through the TLR2 receptor appears to play a role in phagosome trafficking and antimicrobial responses in MAP‐infected bovine mononuclear phagocytes.

Gene Expression and Antimicrobial Activity of Bovine Macrophages in Response to Mycobacterium avium subsp. paratuberculosis

We evaluated gene expression and antimicrobial responses of bovine monocyte—derived macrophages incubated with Mycobacterium avium subsp. paratuberculosis (M. a. ptb), the causative agent of Johnes disease. Gene expression was evaluated by the use of human noncompetitive high-density oligonucleotide microarrays. Bovine messenger RNA hybridized with 14.2–18.2% of the 12,600 oligonucleotide probe sets. When macrophages incubated with M. a. ptb were compared with nonactivated control macrophages, macrophages activated by addition of interferon-γ and lipopolysaccharide, and macrophages incubated with Mycobacterium avium subspecies avium (M. a. a), 47, 79, and 27 genes, respectively, were differentially expressed. Differential expression of six of these genes was confirmed using reverse transcriptase polymerase chain reaction. Several functional assays were performed to evaluate the potential relevance of differentially expressed genes to host defense. Macrophages phagocytizing M. a. a had a greater capacity to kill the organisms and to acidify phagosomes and a greater degree of apoptosis than did macrophages incubated with M. a. ptb. The results of these studies indicate that multiple genes and metabolic pathways are differentially expressed by macrophages ingesting mycobacterial organisms. Although the intracellular fate of mycobacterial organisms appears to be dependent on a complex interaction between macrophage and organism, phagosome acidification and apoptosis may play central roles in organism survival.

Serum protein concentrations in calves with experimentally induced pneumonic pasteurellosis

Ten healthy 2 to 4-week-old Holstein calves were randomly allotted into control and infected groups. Control calves (n=5) were inoculated intrabronchially with 5ml of Dulbeccos phosphate-buffered saline solution (DPBSS). Infected calves (n=5) were inoculated intrabronchially with 5x109 log-phase Mannheimia haemolytica organisms suspended in 5ml of DPBSS. Blood samples were obtained 15 minutes before and one, two, four and six hours after inoculation. Serum protein concentrations were determined by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Serum concentrations of proteins with molecular weights of 125,000 D (ceruloplasmin), 60,000 D (a 1-antitrypsin), 45,000 D (haptoglobin), and 40,000 D (acid glycoprotein) were significantly increased in calves with pneumonic pasteurellosis, compared with concentrations in control calves. Results indicate that acute phase proteins increase more rapidly after the onset of inflammation than previously thought. Measurement of serum protein concentrations may be useful in monitoring the progression of the induced pneumonic pasteurellosis in calves.

Food consumption and energy, water, and nitrogen budgets in captive great-horned owls (Bubo virginianus).

Abstract 1. 1. The metabolizability of diets of laboratory white mice and 1-day-old domestic turkey poults by adult great-horned owls averaged about 67·9 and 71·2 per cent respectively. 2. 2. The metabolizable energies of these two diets were 4304 and 4151 cal/g respectively. 3. 3. The owls ate about 26·5 g/kg (dry weight) of each diet per day. 4. 4. The owls consumed an average of 4·4 per cent of their body weight in water per day. All water consumed was in their food. Sensible water losses amounted to slightly over 50 per cent of water consumed for both diets.

Gastroduodenal electrical activity in turkeys

Bipolar Ag/AgCl electrodes were implanted in the stomach and duodenum of 21 turkeys to study electrical activity in those organs. Intraluminal pressure changes were also monitored. For comparative purposes, electric slow waves were recorded from the ileum of one dog. Slow waves were not observed in the recordings from the stomach of turkeys. Although slow waves were recorded from the duodenum of turkeys, the waves were observed to wax and wane and were possibly not the major regulators of duodenal contractile activity. Several bursts of action potentials and several contractions usually occurred in the duodenum during one slow-wave cycle. Duodenal motility appeared to be totally coordinated with the gastric cycle. Impulses conducted over intrinsic nerves from a gastric pacemaker (15) were proposed as a possible mechanism for initiating and coordinating gastroduodenal motor activity.

Ultrastructural features of ethanol-induced cardiomyopathy in turkey poults

Alcoholic cardiomyopathy, characterized by cardiac hypertrophy, was induced in young turkey poults with 5% ethanol. Ultrastructural features included accumulation of glycogen, swollen mitochondria, myofibrillar lysis, increased number of lysosomes, dilated sarcoplasmic reticulum and dense myofibers. Similarity of these alterations to those described in human alcoholic cardiomyopathy confirms the usefulness of the turkey poult as an animal model for this disease syndrome.