Measurement of the parity-violating asymmetry in inclusive electroproduction of π- near the Δ0 resonance.

The parity-violating (PV) asymmetry of inclusive π- production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasifree photoproduction off the neutron via the Δ0 resonance. In the context of heavy-baryon chiral perturbation theory, this asymmetry is related to a low-energy constant d(Δ)- that characterizes the parity-violating γNΔ coupling. Zhu et al. calculated d(Δ)- in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A(γ)-=-5.2 to +5.2 ppm. The measurement performed in this work leads to A(γ)-=-0.36±1.06±0.37±0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V(ud)/V(us). The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N-Δ axial transition form factors using PV electron scattering.

Transverse beam spin asymmetries at backward angles in elastic electron-proton and quasielastic electron-deuteron scattering.

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108°) for Q² = 0.22 GeV²/c² and 0.63 GeV²/c² at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (πN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.

Determination of the axial-vector weak coupling constant with ultracold neutrons.

A precise measurement of the neutron decay ß asymmetry A0 has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A0 = -0.119 66±0.000 89{-0.001 40}{+0.001 23}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon g{A}/g{V}=-1.275 90{-0.004 45}{+0.004 09}.

Strange quark contributions to parity-violating asymmetries in the backward angle G0 electron scattering experiment.

We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2=0.22 and 0.63 GeV2. They are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of approximately < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial-vector current at these four-momentum transfers.

Characterization of a head-only aerosol exposure system for nonhuman primates.

A well-characterized exposure chamber is necessary to generate reproducible atmospheres for inhalation toxicology studies. The aim of the present study was to characterize a head-only exposure chamber for non-human primates. Aerosols containing bovine serum albumin (BSA) were used to characterize a 16-L dynamic airflow head-only exposure chamber. A 250-ml plastic bottle with a respirator attached located inside the chamber was used to simulate a breathing head. Chamber leak rate, mixing, and aerosol spatial distributions were quantified. The chamber concentration profile was measured at the chamber exhaust using an aerodynamic particle sizer. Aerosol spatial distribution was determined by collecting filter samples at several chamber locations. The particle size distribution was determined by collecting cascade impactor samples at several chamber locations. The estimated chamber leak rate was within standards suggested in the literature. The measured average aerosol residence time was similar to theoretical aerosol residence time, suggesting that the chamber was mixing well. Additionally, the average concentration measured at each of the sampling locations within the chamber was similar, and the within-run coefficients of variation (CV) across all sampling locations was similar to those reported in previously published studies, again suggesting that the aerosol concentration throughout the chamber was uniform. The particle size distribution was similar throughout the exposure chamber. Additionally, the BSA concentration and particle size distributions measured in the breathing zone of the simulated head were not significantly different from measurements made elsewhere in the chamber, suggesting that respiration does not affect the average aerosol concentration or particle size distribution at the mouth.

Aerosolized specific antibody protects mice from lung injury associated with aerosolized ricin exposure.

Parenteral vaccination with ricin toxoid, although protective against death after a lethal aerosol ricin challenge, only partially protects against lung lesions. Therefore, we tested whether passive protection with aerosolized specific anti-ricin IgG (goat polyclonal, affinity-purified) could protect against both lethality and lung lesions in unvaccinated mice. Healthy CD-l mice were administered antibody (Ab) by small particle aerosol. Group 1 received non-specific control Ab (2160 mg/min/m3), and groups 2 and 3 received anti-ricin IgG (960 and 3280 mg/min/m3, respectively). Each group was challenged with a lethal dose of aerosolized ricin 1 hr after Ab exposure. All group 1 (control Ab) mice developed diffuse airway epithelial necrosis, with severe interstitial edema and inflammation involving all lung lobes, and died 48-96 hr post-challenge (PC). In contrast, in groups 2 and 3 at 24 hr PC, lung lesions were absent to very mild although there was rare epithelial necrosis in the upper airways in both groups. By 48 hr PC, necrosis of the tracheal epithelium and peritracheal inflammation were noted in some group 3 mice only. By 4 days PC, lungs and airways did not differ from cage controls in most group 2 and 3 mice. Weight gain in group 2 and 3 mice paralleled that of control mice. At 14 days PC, lungs were no different in controls than in group 3 mice. However, two non-survivors in group 3 had obstructions due to proximal airway epithelial damage. All group 2 mice survived, although a mild lymphoplasmacytic perivasculitis was present at 14 days PC which was not noted in the group 3 mice.

The distribution of [125I]ricin in mice following aerosol inhalation exposure.

Studies were conducted to examine the uptake and redistribution of [125I]ricin from the lungs of mice following nose-only aerosol inhalation exposure. Radiolabelled contents were measured in lung and various extra-pulmonary tissues 15 min through 30 h following 10 min aerosol exposures. Pharmacokinetic analyses were performed on whole-organ data obtained for lungs, stomach, liver and spleen. Radioactivity within the lungs, maximal at 15 min post-exposure, was eliminated in a biexponential fashion with a long beta half-life (approximately 40 h). Large amounts of radiolabel were also found within the gastrointestinal tract. Radiolabel within the stomach exhibited an absorption phase and two-compartment elimination. Radiolabel content of many other tissues, including known accumulation sites for intravenously administered toxin, was significantly (p < 0.05) increased (relative to 15 min post-exposure) in association with the early elimination of radiolabel from the lungs, but levels in these tissues were very low and did not increase after 4 h post-exposure. The only exception was our sample of trachea, which showed delayed elevations in radiolabel (peak at 24 h); this pattern was attributable to the contained thyroid (not removed at necropsy) and its trapping of free [125I] released upon tissue [125I]ricin degradation. The overall data indicate that ricin administered by aerosol inhalation is delivered to both respiratory and gastrointestinal tracts; however, it is not extensively transported from either tract to other potential target sites. Ricin delivered to the lungs is primarily sequestered within the lungs until degradation. Only small amounts of ricin delivered to the gastrointestinal tract are absorbed into the circulation.

Bacterial filamentation of Yersinia pestis by beta-lactam antibiotics in experimentally infected mice.

OBJECTIVE: To identify alternatives to streptomycin for treating pneumonic plague, we evaluated beta-lactam antibiotics to treat experimental pneumonic plague in mice. METHODS: Mice were exposed to a lethal inhaled dose of Yersinia pestis and treated with beta-lactam antibiotics administered every 6 hours, starting 42 hours postexposure. RESULTS: The mice died or were euthanized in extremis 3 days postexposure. We observed marked bacterial filamentation of Y pestis in the tissues of mice treated with ceftazidime (10/10 mice), aztreonam (9/10 mice), or ampicillin (1/10 mice), but not in the tissues of mice treated with cefotetan, cefazolin, ceftriaxone, or saline. There was no evidence of septation of the filamentous bacteria by light or electron microscopy. The filamentous bacteria were confirmed as Y pestis based on their reactivity with rabbit anti-Y pestis F1 serum. CONCLUSIONS: Marked bacterial filamentation of Y pestis can be produced in vivo by certain beta-lactam antibiotics. This antibiotic-induced morphologic change is important because filamentous bacteria in clinical samples could possibly be confused with filamentous actinomycotic organisms.

Pathology of experimental pneumonic plague produced by fraction 1-positive and fraction 1-negative Yersinia pestis in African green monkeys (Cercopithecus aethiops).

OBJECTIVE: The protein capsule of Yersinia pestis, known as Fraction 1 or F1, is a protective immunogen and is an assumed, but not proven, virulence factor. Our objectives were to determine if inhaled F1-negative and/or F1-positive strains of Y pestis were virulent in the African green monkey and, if so, to differentiate F1-negative from F1-positive monkeys. Because F1-negative strains have been isolated from natural sources and have caused experimental fatal disease, we felt that this information was crucial to the development of future vaccines and diagnostic tests. MATERIALS AND METHODS: Adult African green monkeys were exposed by aerosol to F1-positive (CO92, n=15) or F1-negative (CO92-C12, n=6; Java-9, n=2) Y pestis strains. RESULTS: All monkeys died 4 to 10 days postexposure and had lesions consistent with primary pneumonic plague. Antibodies to F1 antigen and other Y pestis antigens allowed us to differentiate F1-positive from F1-negative Y pestis strains in fixed tissues. CONCLUSIONS: In this study, F1 antigen was not a required virulence factor. Therefore, there may be a need for vaccines and diagnostic assays that are not solely based on the F1 antigen.

Recombinant (F1+V) vaccine protects cynomolgus macaques against pneumonic plague.

Cynomolgus macaques, immunised at the 80 µg dose level with an rF1+rV vaccine (two doses, three weeks apart), were fully protected against pneumonic plague following inhalational exposure to a clinical isolate of Yersinia pestis (strain CO92) at week 8 of the schedule. At this time, all the immunised animals had developed specific IgG titres to rF1 and rV with geometric mean titres of 96.83±20.93 µg/ml and 78.59±12.07 µg/ml, respectively, for the 40 µg dose group; by comparison, the 80 µg dose group had developed titres of 114.4±22.1 and 90.8±15.8 µg/ml to rF1 and rV, respectively, by week 8. For all the immunised animals, sera drawn at week 8 competed with the neutralising and protective Mab7.3 for binding to rV antigen in a competitive ELISA, indicating that a functional antibody response to rV had been induced. All but one of the group immunised at the lower 40 µg dose-level were protected against infection; the single animal which succumbed had significantly reduced antibody responses to both the rF1 and rV antigens. Although a functional titre to rV antigen was detected for this animal, this was insufficient for protection, indicating that there may have been a deficiency in the functional titre to rF1 and underlining the need for immunity to both vaccine antigens to achieve protective efficacy against plague. This candidate vaccine, which has been evaluated as safe and immunogenic in clinical studies, has now been demonstrated to protect cynomolgus macaques, immunised in the clinical regimen, against pneumonic plague.

First measurement of the neutron beta asymmetry with ultracold neutrons.

We report the first measurement of an angular correlation parameter in neutron beta decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for approximately 30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2x2pi solenoidal spectrometer. We determine a value for the beta-asymmetry parameter A_{0}=-0.1138+/-0.0046+/-0.0021.

Pathology of inhalational anthrax infection in the african green monkey.

There is a critical need for an alternative nonhuman primate model for inhalational anthrax infection because of the increasingly limited supply and cost of the current model. This report describes the pathology in 12 African green monkeys (AGMs) that succumbed to inhalational anthrax after exposure to a low dose (presented dose 200-2 x 10(4)colony-forming units [cfu]) or a high dose (presented dose 2 x 10(4)-1 x 10(7) cfu) of Bacillus anthracis (Ames strain) spores. Frequent gross lesions noted in the AGM were hemorrhage and edema in the lung, mediastinum, and mediastinal lymph nodes; pleural and pericardial effusions; meningitis; and gastrointestinal congestion and hemorrhage. Histopathologic findings included necrohemorrhagic lymphadenitis of mediastinal, axillary, inguinal, and mesenteric lymph nodes; mediastinal edema; necrotizing splenitis; meningitis; and congestion, hemorrhage, and edema of the lung, mesentery, mesenteric lymph nodes, gastrointestinal tract, and gonads. Pathologic changes in AGMs were remarkably similar to what has been reported in rhesus macaques and humans that succumbed to inhalational anthrax; thus, AGMs could serve as useful models for inhalation anthrax studies.

Duration of protection of rabbits after vaccination with Bacillus anthracis recombinant protective antigen vaccine.

Long-term protection of rabbits that had been vaccinated with two doses of a recombinant protective antigen (rPA) vaccine was examined against an aerosol spore challenge with the Ames isolate of Bacillus anthracis at 6 and 12 months. At 6 months after the primary injection, survival was 74.1% (20/27) with quantitative ELISA titer of 22.3 microg of anti-rPA IgG per millilitre and toxin neutralizing antibody (TNA) assay titer of 332. At 12 months after the primary injection, only 37.5% (9/24) of the rabbits were protected with quantitative ELISA titer of 19.8 microg of anti-rPA IgG per millilitre and TNA assay titer of 286. There was a significant loss of protection (p = 0.0117) and a significant difference in survival curves (p = 0.0157) between the 6- and 12-month groups. When ELISA or TNA assay titer, gender, and challenge dose were entered into a forward logistic regression model, week 26 ELISA titer (p = 0.0236) and week 13 TNA assay titer (p = 0.0147) for the 6-month group, and week 26 ELISA titer (p = 0.0326) and week 8 TNA assay titer (p = 0.0190) for the 12-month group, were significant predictors of survival. Neither gender nor challenge dose were identified as having a statistically significant effect on survival. Booster vaccinations with rPA may be required for the long-term protection of rabbits against anthrax.

Lesions of acute inhaled lethal ricin intoxication in rhesus monkeys.

Five unimmunized adult rhesus monkeys weighing 5.9-6.3 kg were challenged with a precalculated, inhaled dose of 20.95-41.8 micrograms/kg of aerosolized ricin. Two males and three females either died or were killed at the onset of respiratory distress between 36 and 48 hours post-ricin inhalation and were necropsied. Consistent gross and microscopic lesions were confined to the thoracic cavity. All monkeys had multifocal to coalescing fibrinopurulent pneumonia, diffuse necrosis, and acute inflammation of airways, and nearly diffuse alveolar flooding, with peribronchovascular edema. All monkeys also had purulent tracheitis, fibrinopurulent pleuritis, and purulent mediastinal lymphadenitis. One male monkey and one female monkey had bilateral adrenocortical necrosis. We attributed the cause of death to asphyxiation following massive pulmonary alveolar flooding. The lesions of acute inhaled ricin intoxication in rhesus monkeys closely resembled those lesions reported in rats with acute inhaled ricin intoxication.

Hypersensitivity among woodworkers in South Africa.

A group of South African woodworkers was investigated in respect of allergenic activity of three indigenous woods, yellowwood, stinkwood and blackwood, and Brazilian imbuia. Histories were taken, skin-prick tests performed, and total serum IgE levels estimated. A high rate of skin sensitivity was found, as well as previously undocumented skin sensitivities to stinkwood and yellowwood.

Comparative efficacy of a Coxiella burnetii chloroform:methanol residue (CMR) vaccine and a licensed cellular vaccine (Q-Vax) in rodents challenged by aerosol.

Q fever is an acute and self-limited febrile illness caused by the obligate intracellular bacterium Coxiella burnetii. While phase I cellular Q fever vaccines are efficacious in humans, vaccination of immune individuals may result in sterile abscesses and granulomas. The chloroform:methanol residue vaccine (CMR) was developed as a safer alternative. The efficacy of a licensed phase I cellular vaccine (Q-Vax) was compared with that of CMR vaccine in A/J mice and Hartley guinea pigs challenged with virulent phase I C. burnetii by aerosol. Both vaccines were efficacious. The CMR vaccine dose required to protect 50% of mice (PD50) against lethal aerosol challenge (11 LD50) was one-third of the Q-Vax dose. However, the PD50 for CMR was four times the Q-Vax dose in guinea pigs challenged by aerosol (60 LD50). It was concluded that CMR is an efficacious alternative to cellular Q fever vaccines for the prevention of Q fever.

Determination of the virulence of the pigmentation-deficient and pigmentation-/plasminogen activator-deficient strains of Yersinia pestis in non-human primate and mouse models of pneumonic plague.

The current human plague vaccine, a killed Yersinia pestis whole-cell preparation, does not protect against aerosol challenge and is reactogenic and antigenically undefined. Live attenuated Y. pestis, such as pigmentation-deficient (Pgm-) strains, have been used frequently as vaccines and are efficacious. They are used widely in plague research and assumed to be safe. However, they can cause serious adverse reactions, and their aerosol infectivity is not known. We tested the virulence of a defined Pgm- variant of the C092 strain of Y. pestis in mouse and non-human primate models of pneumonic plague. The ten-fold lower median lethal dose by the aerosol compared to the subcutaneous (s.c.) routes of the Pgm- strain in mice suggested that the Pgm- strain might be less attenuated by the former than by the latter route. After exposure of 16 African green monkeys to inhaled doses ranging from 1.1 x 10(4) to 8.1 x 10(7)cfu, eight died and eight survived. The terminal cultures collected from five of the non-survivors were all positive for Y. pestis. Two of the remaining three non-survivors were culture-negative but had pathologic and immunologic evidence of infection with Y. pestis, specimens could not be obtained nor the cause of death determined for the third one. The deaths were not dose-related, and there were some differences in the pathology associated with infection by the Pgm- strain compared to the wild-type (wt) strain. However, the Pgm- derivative was clearly virulent for monkeys by the aerosol route. A mutant of the Pgm- strain, which has a deletion in the plasminogen activator (Pla) virulence locus (pla), appeared to be more attenuated than was either the Pgm- single mutant (in NHPs and mice) or the Pla- single mutant strain (in mice) and has potential as a live vaccine.

Comparison of the pulmonary distribution and efficacy of antibodies given to mice by intratracheal instillation or aerosol inhalation.

The respiratory tract is the portal of entry and target organ of many aerosolized toxins and infective agents, and there is increasing need for testing the efficacy of potential therapeutic agents delivered directly into the lungs. Intratracheal instillation and aerosol inhalation are the two methods most often used to introduce drugs, toxins, or infective agents into the respiratory tract of experimental animals. In this study we compared the distribution and efficacy of antibodies given to mice by aerosol inhalation or intratracheal instillation. We determined the pulmonary distribution of these antibodies by immunohistochemistry and observed the distribution and severity of pulmonary lesions that developed after exposure to aerosolized ricin. Although antibodies administered by either method prevented death, we found that instilled antibodies tended to concentrate around terminal airways and often failed to reach peripheral lung fields. Sometimes entire lung lobes were missed by the instillation route. Acute and chronic pulmonary lesions developed in the unprotected areas of instillation-treated lungs. In contrast, aerosolized antibodies covered all pulmonary surfaces and effectively prevented ricin-induced lesions throughout the lungs. Our findings suggest that the aerosol inhalation method may be preferable for evaluating the efficacy of therapeutic agents in the respiratory tract because of the failure of instilled agents to reach and protect peripheral alveoli.