19 research outputs found
Pregnancy and Breast Cancer: when They Collide
Women of childbearing age experience an increased breast cancer risk associated with a completed pregnancy. For younger women, this increase in breast cancer risk is transient and within a decade after parturition a cross over effect results in an ultimate protective benefit. The post-partum peak of increased risk is greater in women with advanced maternal age. Further, their lifetime risk for developing breast cancer remains elevated for many years, with the cross over to protection occurring decades later or not at all. Breast cancers diagnosed during pregnancy and within a number of years post-partum are termed pregnancy-associated or PABC. Contrary to popular belief, PABC is not a rare disease and could affect up to 40,000 women in 2009. The collision between pregnancy and breast cancer puts women in a fear-invoking paradox of their own health, their pregnancy, and the outcomes for both. We propose two distinct subtypes of PABC: breast cancer diagnosed during pregnancy and breast cancer diagnosed post-partum. This distinction is important because emerging epidemiologic data highlights worsened outcomes specific to post-partum cases. We reported that post-partum breast involution may be responsible for the increased metastatic potential of post-partum PABC. Increased awareness and detection, rationally aggressive treatment, and enhanced understanding of the mechanisms are imperative steps toward improving the prognosis for PABC. If we determine the mechanisms by which involution promotes metastasis of PABC, the post-partum period can be a window of opportunity for intervention strategies
Dispersibility of glacial loess in particle size analysis, USA.
Silt- to sand-size clay aggregates are absent or relatively rare in unweathered glacial loesses, but dominant in parna where they resist dispersion in particle size analysis (PSA). There are reports that some aggregates in glacial loesses also resist dispersion. However, one would expect freeze-dried aggregates to have mostly edge-to-face orientation of the platy clays and to be easily dispersed in PSA. We test this hypothesis in this paper. We selected Midwest and Alaskan soils formed in late-Pleistocene loess derived from glacial outwash and floodplains beyond the late-Pleistocene glacial boundary. Analytical methods are those in use by the National Soil Survey Laboratory. Soil A and B horizons dispersed well as shown by the 1.5 MPa water to clay ratios of <0.6. In the C horizon, silt-size, rounded, compound particles (aggregates) were few to common and randomly distributed. A few were volcanic glass. Other aggregates consisted of carbonates or layer silicates. Layer silicate aggregates dispersed well in PSA, as hypothesised; Fe and carbonate cemented aggregates did not. Most of these dispersed when given an ultrasonic dispersion treatment
Sedimentary aggregates in the Peoria Loess of Nebraska, USA
Loess grain size data used to infer transport direction or wind strength are generally derived from vigorously disaggregated samples. However, these data may not adequately represent the effective particle size distribution during loess transport, if th