Evaluation of a multivalent Pasteurella haemolytica vaccine in bighorn sheep: protection from experimental challenge.

The efficacy of a multivalent Pasteurella haemolytica vaccine (A1, A2, T10) in reducing morbidity and mortality associated with pneumonic pasteurellosis in bighorn sheep (Ovis canadensis) was examined. Fifteen captive bighorns were divided equally into three treatment groups based on vaccination status: control (no vaccination), one dose 10 days prior to challenge, or one or two doses 57 wk prior to challenge. At challenge, each bighorn received about 6.2 x 10(7) colony forming units of P. haemolytica (biotype T, serotype 10, biogroup 4-CDS; ribotype ECO; "Alamosa Canyon" strain) suspension sprayed into the proximal trachea. Vaccination reduced (P = 0.1) mortality in bighorns vaccinated 10 days prior to challenge as compared to controls. Although mortality rates in bighorns vaccinated 57 wk prior to challenge did not differ from controls (P = 0.26), a trend in reduced mortality was apparent. Ranked cumulative postmortem scores based on observed gross lesions and bacteriology did not differ (P > or = 0.14) between vaccinated animals and control animals. Neutralizing antibody titers to P. haemolytica leukotoxin were elevated (P = 0.003) at challenge in bighorns vaccinated 10 days before challenge, and neutralizing titers in bighorns from both vaccinated groups were elevated at death < or = 7 days after challenge (P < or = 0.004). In contrast, agglutinating antibody titers to P. haemolytica serotype A1 or T10 surface antigens did not differ between vaccinated and unvaccinated bighorns (P > or = 0.19). Based on these data, we believe that this experimental P. haemolytica vaccine is safe and can stimulate protective immunity from pneumonic pasteurellosis in bighorn sheep. Further evaluation of this vaccine as a tool in preventing and managing pasteurellosis in wild bighorn sheep appears warranted.

Effect of simulated stress on susceptibility of bighorn sheep neutrophils to Pasteurella haemolytica leukotoxin.

We examined the effects of simulated stress on susceptibility of Rocky Mountain bighorn sheep (Ovis canadensis canadensis) neutrophils to Pasteurella haemolytica leukotoxin in a blocked, crossover experiment. Ten captive-raised bighorn sheep were sampled 10 hr after separate administrations of long-acting adrenocorticotrophic hormone (ACTH) gel and normal saline (control). We then compared in vitro leukotoxin-dependent neutrophil death rates after exposure to culture supernatants from four unique P. haemolytica isolates (one from domestic and three from bighorn sheep). Simulated stress effects were evidenced by elevated (P = 0.002) mean plasma cortisol concentrations, more neutrophils (P = 0.037), and fewer lymphocytes and eosinophils (P < or = 0.043) in ACTH-treated bighorn sheep. Maximum leukotoxin-dependent neutrophil death rates were > or = 61% for three of four P. haemolytica isolates tested. For all three cytotoxic isolates, neutrophil death rates at 150 micrograms/50 microliters supernatant were about 1.13 times higher (P = 0.0001) after bighorns received ACTH; for two of these, overall neutrophil death rates were higher (P < or = 0.001) in ACTH-treated bighorn sheep. Although variable leukotoxin production among P. haemolytica strains appeared principally responsible for differences in leukotoxin-dependent neutrophil death rates, susceptibility of bighorn sheep neutrophils to leukotoxin was increased by prior exposure to elevated plasma cortisol concentrations. It follows that if similar processes occur in neutrophils and alveolar macrophages in vivo, they could contribute to greater susceptibility of stressed bighorn sheep to pneumonic pasteurellosis.

Effects of embedded tungsten-bismuth-tin shot and steel shot on mallards (Anas platyrhynchos).

We assessed the potential for embedded steel and tungsten-bismuth-tin (TBT) shot to adversely affect health of mallards (Anas platyrhynchos). Ducks were implanted with three number four steel (n = 19) or TBT (n = 20) shot pellets in their pectoral muscles. None of seven hematology parameters measured differed in response to treatment (P > or = 0.17). At necropsy 1, 2, 4, and 8 wk posttreatment, we observed only localized tissue reactions to embedded steel or TBT shot. Reactions differed grossly: after wk 1, embedded steel shot were enveloped in 0.5 to 2 mm grayish capsules, whereas TBT shot were surrounded by thinner (< 0.5 mm), translucent capsules. Corrosion of steel shot was apparent. Microscopic lesions associated with steel shot were characterized by moderate to severe histiocytic and lymphocytic inflammation and considerable particle deposition, whereas histiocytic inflammation was mild and particle deposition minimal in TBT lesions. Overall scores of inflammation at steel shot implant sites were greater (P < or = 0.043) than at TBT sites during wk 1 and 8. Inflammation at steel implant sites was relatively consistent over the 8-wk period, but decreased (P = 0.0017) at TBT sites by wk 8. Weights of steel shot recovered from muscle tissue declined logarithmically (R2 = 0.978, P = 0.0014) over 8 wk, but TBT shot weights remained unchanged (P = 0.255). Embedded TBT shot, as compared to steel, resisted corrosion and induced comparatively mild inflammatory responses in mallard muscle tissue. However, inflammatory reactions to both embedded steel and TBT shot were localized and had no detectable systemic effects on mallard health under experimental conditions.

A 160-femtosecond optical image processor based on a conjugated polymer.

Degenerate ground-state conjugated polymers exhibit large third-order nonlinear optical susceptibilities, including substantial two-photon absorption. With the use of a machine architecture suited to these material properties, ultrafast optical processors are possible. A four-wave mixing optical correlator was built with an air-stable, processable, degenerate ground-state conjugated polymer, poly(1,6-heptadiester). The continuously updatable processor correlates two 5000-pixel images in less than 160 femtoseconds, achieving peak processing rates of 3 x 10(16) operations per second.