Breast cancer risk is increased in the years following false-positive breast cancer screening

A small number of studies have investigated breast cancer (BC) risk among women with a history of false-positive recall (FPR) in BC screening, but none of them has used time-to-event analysis while at the same time quantifying the effect of false-negative diagnostic assessment (FNDA). FNDA occurs when screening detects BC, but this BC is missed on diagnostic assessment (DA). As a result of FNDA, screenings that detected cancer are incorrectly classified as FPR. Our study linked data recorded in the Flemish BC screening program (women aged 50-69 years) to data from the national cancer registry. We used Cox proportional hazards models on a retrospective cohort of 298 738 women to assess the association between FPR and subsequent BC, while adjusting for potential confounders. The mean follow-up was 6.9 years. Compared with women without recall, women with a history of FPR were at an increased risk of developing BC [hazard ratio = 2.10 (95% confidence interval: 1.92-2.31)]. However, 22% of BC after FPR was due to FNDA. The hazard ratio dropped to 1.69 (95% confidence interval: 1.52-1.87) when FNDA was excluded. Women with FPR have a subsequently increased BC risk compared with women without recall. The risk is higher for women who have a FPR BI-RADS 4 or 5 compared with FPR BI- RADS 3. There is room for improvement of diagnostic assessment: 41% of the excess risk is explained by FNDA after baseline screening

Euler buckling instability and enhanced current blockade in suspended single-electron transistors

Single-electron transistors embedded in a suspended nanobeam or carbon nanotube may exhibit effects originating from the coupling of the electronic degrees of freedom to the mechanical oscillations of the suspended structure. Here, we investigate theoretically the consequences of a capacitive electromechanical interaction when the supporting beam is brought close to the Euler buckling instability by a lateral compressive strain. Our central result is that the low-bias current blockade, originating from the electromechanical coupling for the classical resonator, is strongly enhanced near the Euler instability. We predict that the bias voltage below which transport is blocked increases by orders of magnitude for typical parameters. This mechanism may make the otherwise elusive classical current blockade experimentally observable.Comment: 15 pages, 10 figures, 1 table; published versio

Correction for Extraneous Background in X-Ray Microanalysis of Cell Cultures

Some practical aspects of the X-ray microanalysis of cell cultures have been investigated. Cells were cultured on titanium grids covered with Formvar films and analyzed at 100 kV either in the scanning transmission (STEM) or transmission mode (TEM) of the electron microscope. Different holders, grids and configurations were compared with respect to the relative contribution of different factors to the extraneous background in the X-ray spectrum. When low atomic number holders are used, the contribution to the spectrum of electrons scattered through high angles, may be negligible. In practice this may result in negative values for the contribution of these scattered electrons to the background. Computer programs for correction of the extraneous background should ignore these negative values and replace them by zero. When a brass holder is used, the contribution to the spectrum from electrons scattered through high angles becomes more important than that of the uncollimated radiation. The position of the analyzed cell relative to the grid bars is more important than the choice of grid or holder type. The data show that for the specimens used in the present study the correction for extraneous background is of little importance and can be neglected

X-Ray Microanalysis of Epithelial and Secretory Cells in Culture

Cell cultures can be used to study ion transport processes. X-ray microanalysis of cell cultures at the cellular level gives interesting information that can complement electrophysiological and tracer studies. In this paper, methods for culturing and preparing a variety of epithelial and secretory cells (fibroblasts, insulinoma cells, bovine mammary epithelial cells, colon cancer cells) for X-ray microanalysis are presented. Results show that sometimes cell cultures are not homogeneous with respect to ion content or reaction to physiological stimuli. In colon cancer cell cultures, a high K and a low K cell subpopulation was found; these subpopulations also differed with respect to other elements. As examples of biological applications, chloride efflux was studied in fibroblasts and colon cancer cells, and strontium uptake in insulinoma cells. Chloride efflux from colon cancer cells is stimulated by cyclic AMP and vaso-active intestinal peptide (VIP), and can be inhibited by pretreatment of the cells with phorbol myristate acetate, which downregulates the cAMP-regulated chloride efflux mechanism

Effect of Chronic Treatment with Diuretics on Mouse Liver: A Morphological and Microanalytical Investigation

In an attempt to produce an animal model for the disease cystic fibrosis (CF), mice were treated chronically with the diuretics amiloride and furosemide, in order to cause chronic inhibition of transepithelial ion transport. Experiments were carried out on adult mice (2 months treatment); in addition, pregnant mice were treated with diuretics, and tissue from offspring 2 and 7 days post partum was investigated. Since biliary cirrhosis is a common occurrence in CF, hepatocytes in the treated mice were investigated by X-ray microanalysis and by light and electron microscopy. Treatment with amiloride caused a significant decrease in cellular Na concentration in adult animals and in in utero treated mice 2 days after birth. The decrease in Na was parallelled by a decrease in Cl, but K levels were not affected. Furosemide caused a slight increase of cellular Na concentrations, especially in animals aged 7 days. In the adult animals, both amiloride and furosemide caused a significant decrease of the cellular Na and Cl levels. No signs of cirrhosis could be observed. Inconsistent changes in the accumulation of lipid droplets in hepatocytes of adult animals treated with amiloride were observed by electron microscopy. It can be concluded that chronic treatment with diuretics, even though it causes some, possibly pathological, changes of the liver, is only of very limited value for generating an animal model to study liver disease in CF

Discontinuous Euler instability in nanoelectromechanical systems

We investigate nanoelectromechanical systems near mechanical instabilities. We show that quite generally, the interaction between the electronic and the vibronic degrees of freedom can be accounted for essentially exactly when the instability is continuous. We apply our general framework to the Euler buckling instability and find that the interaction between electronic and vibronic degrees of freedom qualitatively affects the mechanical instability, turning it into a discontinuous one in close analogy with tricritical points in the Landau theory of phase transitions.Comment: 4+ pages, 3 figures, published versio