Experimental Infection of Richardson’s Ground Squirrels (\u3ci\u3eSpermophilus Richardsonii\u3c/i\u3e ) With Attenuated and Virulent Strains pf \u3ci\u3eBrucella abortus\u3c/i\u3e

A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various nontarget species suggested that Richardson’s ground squirrels (Spermophilus richardsonii) may develop persistent infections when orally inoculated with the vaccine. In the present study, sRB51, B. abortus strain 19 (s19), and virulent B. abortus strain 9941 (s9941) were administered orally to Richardson’s ground squirrels to further characterize B. abortus infection in this species. Six groups of nongravid ground squirrels were orally inoculated with 6x108 colony forming units (cfu) sRB51 (n=10), 2.5x104 cfu s19 (n=10), 2.5x107 cfu s19 (n=6), 1.3x106 cfu s9941 (n=5), 2.1x108 cfu s9941 (n=5), or vaccine diluent (control; n=4). One of five animals in the lower-dose s19 group and two of three animals in the higher-dose s19 group showed persistence of bacteria in various tissues at 14 wk post-inoculation (PI). At 18 wk PI, one of five animals in the sRB51 group and one of five animals in the high-dose s9941 group were culture positive. Although we did detect some persistence of B. abortus strains at 18 wk, we found no evidence of pathology caused by B. abortus strains in nonpregnant Richardson’s ground squirrels based on clinical signs, gross lesions, and microscopic lesions

Development of a Model of Natural Infection with \u3ci\u3eMycobacterium bovis\u3c/i\u3e in White-Tailed Deer

The objective of this study was to develop a suitable experimental model of natural Mycobacterium bovis infection in white-tailed deer (Odocoileus virginianus), describe the distribution and character of tuberculous lesions, and to examine possible routes of disease transmission. In October 1997, 10 mature female white-tailed deer were inoculated by intratonsilar instillation of 2 3 103 (low dose) or 2 3 105 (high dose) colony forming units (CFU) of M. bovis. In January 1998, deer were euthanatized, examined, and tissues were collected 84 to 87 days post inoculation. Possible routes of disease transmission were evaluated by culture of nasal, oral, tonsilar, and rectal swabs at various times during the study. Gross and microscopic lesions consistent with tuberculosis were most commonly seen in medial retropharyngeal lymph nodes and lung in both dosage groups. Other tissues containing tuberculous lesions included tonsil, trachea, liver, and kidney as well as lateral retropharyngeal, mandibular, parotid, tracheobronchial, mediastinal, hepatic, mesenteric, superficial cervical, and iliac lymph nodes. Mycobacterium bovis was isolated from tonsilar swabs from 8 of 9 deer from both dosage groups at least once 14 to 87 days after inoculation. Mycobacterium bovis was isolated from oral swabs 63 and 80 days after inoculation from one of three deer in the low dose group and none of four deer in the high dose group. Similarly, M. bovis was isolated from nasal swabs 80 and 85 days after inoculation in one of three deer from the low dose group and 63 and 80 days after inoculation from two of four deer in the high dose group. Intratonsilar inoculation with M. bovis results in lesions similar to those seen in naturally infected white-tailed deer; therefore, it represents a suitable model of natural infection. These results also indicate that M. bovis persists in tonsilar crypts for prolonged periods and can be shed in saliva and nasal secretions. These infected fluids represent a likely route of disease transmission to other animals or humans

Defensin Susceptibility and Colonization in the Mouse Model of AJ100, a Polymyxin B-Resistant, Brucella abortus RB51 Isolate

Intracellular pathogens selected for increased susceptibility to polycations are commonly attenuated, yet the effect of decreased susceptibility to polycations on pathogenicity has not been researched. The polymyxin-resistant mutant Brucella abortus AJ100 was characterized by comparing its susceptibility to the polycationic antibiotic polymyxin B, defensins, and lactoferricin, and its colonization and clearance in the mouse model to the parent strain RB51. MIC (minimum inhibitory concentration) values determined by Etest for AJ100 and RB51 were 1.5 and 0.25 μg/ml, respectively. Though AJ100 is less susceptible to polymyxin B than RB51, it was more susceptible than its parent strain to the cationic defensins melittin, magainin 2, and cecropin P1. In the mouse model, initial colonization of the spleen was lower for AJ100 than RB51, and the rate of clearance from the spleen was faster for AJ100 than RB51. However, initial colonization and clearance rates of AJ100 from the liver were indistinguishable from those of RB51. This study suggests that the susceptibility profile of Brucella to polycationic defensins rather than polymyxin B may be indicative of differential survival in the spleen and liver in the mouse and is indicative of spleen and liver residential macrophages’ differing ability to inactivate Brucella

On the revealed comparative advantages of Dutch cities

Davis and Dingel explain the distributions of skills, occupations, and sectors across cities. Their model predicts that larger cities will be relatively skill-abundant and specialize in skill-intensive activities. This relates the model to factor-driven comparative advantages. They also develop an elasticity test and pairwise comparison test for the spatial distributional implications of the model. What is not analyzed, however, is the associated structure of trade flows. This next step—the analysis of the structure of trade—is the main contribution of our article. We combine micro-economic data to analyze how the sorting process of factors of production across cities determines the revealed comparative advantage (RCA) distributions of Dutch cities. We find that (i) the sorting of factors of production across cities is consistent with Davis and Dingel, (ii) RCA patterns differ significantly across locations, (iii) RCA differences can be explained by the interaction of local skill-abundance and sector skill-intensity (in line with the factor abundance model), and (iv) the RCA analysis relative to the Netherlands mostly, but not always, coincides with that relative to the world

Safety Of \u3ci\u3eBrucella Abortus\u3c/i\u3e Strain Rb51 In Black Bears

In two studies conducted from October 1999 to March 2000 and December 2000 to April 2001, adult black bears (Ursus americanus) were orally inoculated with 1.4–3.1X1010 colony-forming units (CFU) of Brucella abortus strain RB51 (SRB51, n=12) or 2 ml of 0.15 M NaCl solution (saline, n=11). We did not detect a difference (P\u3e0.05) in antibody titers to SRB51 in serum obtained before vaccination, at 8 wk after vaccination, or at necropsy at 21 or 23 wk after vaccination between SRB51-vaccinated and nonvaccinated bears. The SRB51 vaccine strain was recovered from tissues obtained at necropsy from one of six SRB51-vaccinated bears in study 1, but none of the six SRB51-vaccinated bears in study 2. Vaccination of black bears with SRB51 did not appear to influence (P\u3e0.05) reproductive performance

Bilateral Vallecular Cysts as a Cause of Dysphagia: Case Report and Literature Review

Cysts of the vallecula are rare, accounting for 10.5% to 20.1% of all laryngeal cysts. Vallecular cysts may present with diverse symptoms affecting the voice, airway, and swallowing. We describe the evaluation and treatment of a 70-year-old woman who presented with dysphagia caused by large bilateral vallecular cysts

High-impact animal health research conducted at the USDA’s National Animal Disease Center

Commissioned by President Dwight Eisenhower in 1958 and opened with a dedication ceremony in December 1961, the USDA, Agricultural Research Service (ARS), National Animal Disease Center (NADC) celebrated its 50-year anniversary in November 2011. Over these 50 years, the NADC established itself among the world’s premier animal health research centers. Its historic mission has been to conduct basic and applied research on selected endemic diseases of economic importance to the U.S. livestock and poultry industries. Research from NADC has impacted control or management efforts on nearly every major animal disease in the United States since 1961. For example, diagnostic tests and vaccines developed by NADC scientists to detect and prevent hog cholera were integral in the ultimate eradication of this costly swine disease from the U.S. Most major veterinary vaccines for critical diseases such as brucellosis and leptospirosis in cattle, porcine respiratory and reproductive syndrome (PRRS), porcine parvovirus and influenza in swine had their research origins or were developed and tested at the NADC. Additional discoveries made by NADC scientists have also resulted in the development of a nutritional approach and feed additives to prevent milk fever in transition dairy cattle. More recently, NADC’s archive of historic swine influenza viruses combined with an established critical mass of influenza research expertise enabled NADC researchers to lead an effective national research response to the pandemic associated with the novel 2009 H1N1 influenza virus. This review commemorates some of the key animal health contributions in NADC’s first 50 years, recaps the newly completed modernization of the center into new facilities, and offers highlights of the ongoing research that will define NADC’s mission going forward

The Global Structure of UTLS Ozone in GEOS-5: A Multi-Year Assimilation of EOS Aura Data

Eight years of ozone measurements retrieved from the Ozone Monitoring Instrument (OMI) and the Microwave Limb Sounder, both on the EOS Aura satellite, have been assimilated into the Goddard Earth Observing System version 5 (GEOS-5) data assimilation system. This study thoroughly evaluates this assimilated product, highlighting its potential for science. The impact of observations on the GEOS-5 system is explored by examining the spatial distribution of the observation-minus-forecast statistics. Independent data are used for product validation. The correlation coefficient of the lower-stratospheric ozone column with ozonesondes is 0.99 and the bias is 0.5%, indicating the success of the assimilation in reproducing the ozone variability in that layer. The upper-tropospheric assimilated ozone column is about 10% lower than the ozonesonde column but the correlation is still high (0.87). The assimilation is shown to realistically capture the sharp cross-tropopause gradient in ozone mixing ratio. Occurrence of transport-driven low ozone laminae in the assimilation system is similar to that obtained from the High Resolution Dynamics Limb Sounder (HIRDLS) above the 400 K potential temperature surface but the assimilation produces fewer laminae than seen by HIRDLS below that surface. Although the assimilation produces 5 - 8 fewer occurrences per day (up to approximately 20%) during the three years of HIRDLS data, the interannual variability is captured correctly. This data-driven assimilated product is complementary to ozone fields generated from chemistry and transport models. Applications include study of the radiative forcing by ozone and tracer transport near the tropopause

Convergence towards a European strategic culture? A constructivist framework for explaining changing norms.

The article contributes to the debate about the emergence of a European strategic culture to underpin a European Security and Defence Policy. Noting both conceptual and empirical weaknesses in the literature, the article disaggregates the concept of strategic culture and focuses on four types of norms concerning the means and ends for the use of force. The study argues that national strategic cultures are less resistant to change than commonly thought and that they have been subject to three types of learning pressures since 1989: changing threat perceptions, institutional socialization, and mediatized crisis learning. The combined effect of these mechanisms would be a process of convergence with regard to strategic norms prevalent in current EU countries. If the outlined hypotheses can be substantiated by further research the implications for ESDP are positive, especially if the EU acts cautiously in those cases which involve norms that are not yet sufficiently shared across countries

Response Function of the Fractional Quantized Hall State on a Sphere I: Fermion Chern-Simons Theory

Using a well known singular gauge transformation, certain fractional quantized Hall states can be modeled as integer quantized Hall states of transformed fermions interacting with a Chern-Simons field. In previous work we have calculated the electromagnetic response function of these states at arbitrary frequency and wavevector by using the Random Phase Approximation (RPA) in combination with a Landau Fermi Liquid approach. We now adopt these calculations to a spherical geometry in order to facilitate comparison with exact diagonalizations performed on finite size systems.Comment: 39 pages (REVTeX 3.0). Postscript file for this paper are available on the World Wide Web at http://cmtw.harvard.edu/~simon/ ; Preprint number HU-CMT-94S0