Curing of Plasmid pXO1 from Bacillus anthracis Using Plasmid Incompatibility

The large plasmid pXO1 encoding the anthrax toxin is important for the virulence of Bacillus anthracis. It is essential to cure pXO1 from B. anthracis to evaluate its role in the pathogenesis of anthrax infection. Because conventional methods for curing plasmids (e.g., curing agents or growth at elevated temperatures) can induce mutations in the host chromosomal DNA, we developed a specific and reliable method to eliminate pXO1 from B. anthracis using plasmid incompatibility. Three putative replication origins of pXO1 were inserted into a temperature-sensitive plasmid to generate three incompatible plasmids. One of the three plasmids successfully eliminated the large plasmid pXO1 from B. anthracis vaccine strain A16R and wild type strain A16. These findings provided additional information about the replication/partitioning of pXO1 and demonstrated that introducing a small incompatible plasmid can generate plasmid-cured strains of B. anthracis without inducing spontaneous mutations in the host chromosome

Race-Ethnic Differences of Sleep Symptoms in an Elderly Multi-Ethnic Cohort: The Northern Manhattan Study

BACKGROUND: Sleep disorders are associated with stroke and may vary among elderly Hispanics, Blacks and Whites. We evaluated differences in sleep symptoms by race-ethnicity in an elderly population-based urban community sample. METHODS: Snoring, daytime sleepiness and reported sleep duration were ascertained by standardized interviews as a part of the Northern Manhattan Study, a prospective cohort study of vascular risk factors and stroke risk in a multi-ethnic urban population. Sleep symptoms were compared amongst race-ethnic groups using logistic regression models. RESULTS: A total of 1,964 stroke-free participants completed sleep questionnaires. The mean age was 75 ± 9 years, with 37% men, with 60% Hispanics, 21% Blacks and 19% Whites. In models adjusted for demographic and vascular risk factors, Hispanics had increased odds of frequent snoring (odds ratio, OR: 3.6, 95% confidence interval, CI: 2.3–5.8) and daytime sleepiness (OR: 2.8, 95% CI: 1.7–4.5) compared to White participants. Hispanics were more likely to report long sleep (≥9 h of sleep, OR: 1.8, 95% CI: 1.1–3.1). There was no difference in sleep symptoms between Black and White participants. CONCLUSION: In this cross-sectional analysis among an elderly community cohort, snoring, sleepiness and long sleep duration were more common in Hispanics. Sleep symptoms may be surrogate markers for an underlying sleep disorder which may be associated with an elevated risk of stroke and may be modified by clinical intervention