Background Autoantibodies are of growing interest in cancer research as potential biomarkers; yet the determinants of autoimmunity are not well understood. Antinuclear antibodies (ANA) are common in the general population, and are more prevalent in women and older adults. Here we examined the relationship of ANA with reproductive and hormonal factors in a representative sample of U.S. women. Methods We analyzed data on reproductive history and exogenous hormone use in relation to serum ANA in 2,037 females ages 12 and older from the National Health and Nutrition Examination Survey (NHANES; 1999–2004). Estimated ANA prevalences were adjusted for sampling weights. Prevalence odds ratios (POR) and 95% confidence intervals (CI) were adjusted for age, race and poverty-income-ratio, and models were stratified by menopause status. Results In premenopausal women ages 20 and older, ANA prevalence was associated with parity (p<0.001; parous versus nulliparous POR=2.0; 95%CI 1.2, 3.4), but in parous women ANA did not vary by number of births, age at first birth, years since last birth or breastfeeding. In postmenopausal women, ANA prevalence was associated with an older age at menarche (p=0.019; age 16–20 versus 10–12 years POR=3.0, 95%CI 1.6, 5.9), but not with parity. Oral contraceptives and estrogen therapy were not associated with a higher ANA prevalence. Conclusions Childbearing (having had one or more births) may explain age-associated elevations in ANA prevalence seen in premenopausal women. Impact These findings highlight the importance of considering reproductive history in studies of autoimmunity and cancer in women.

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The problem of estimating parameters of a multivariate normal p-dimensional random vector is considered for a banded covariance structure reflecting m-dependence. A simple non-iterative estimation procedure is suggested which gives an explicit, unbiased and consistent estimator of the mean and an explicit and consistent estimator of the covariance matrix for arbitrary p and m.

Nonlinear dynamics of the magnetic electron drift mode turbulence is outlined and generation of large-scale magnetic structures in a nonuniform unmagnetized plasma by turbulent Reynolds stress is demonstrated. A two-component turbulent system consisting of magnetic fluctuations and generated secondary flows is considered. The evolution equations for mean magnetic flow generation are obtained by averaging the two-field model equations over fast small scales. It is found, in turn, that the pattern of the flow modulates and regulates the turbulence dynamics. The main features of the flows are controlled by the structure of the nonlinear coupling to the small-scale magnetic fluctuations as well as by the spectral properties of the turbulence and its anisotropy. Thus, the parent waves and secondary magnetic flows form a self-regulating system. It is shown that the presence of large-scale structures leads to shearing of turbulence. The k-space diffusion coefficient for the magnetic zonal flows and streamers are calculated.