Mayo Clinic

About: Mayo Clinic is a healthcare organization based out in Rochester, Minnesota, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 63387 authors who have published 169578 publications receiving 8114006 citations.

Caveolins, liquid-ordered domains, and signal transduction.

Abstract: Caveolae were originally identified as flask-shaped invaginations of the plasma membrane in endothelial and epithelial cells (14). Prior to the development of biochemical methods for their purification, caveolae were thought to principally mediate the transcellular movement of molecules (101, 145). Recently, the development of novel purification procedures has greatly expanded our knowledge regarding the putative functions of caveolae in vivo. In this review, we seek to update the working definition of caveolae, describe the functional roles of the caveolin gene family, and summarize the evidence that supports a role for caveolae as mediators of a number of cellular signaling processes.

The national lung screening trial: Overview and study design

Abstract: The National Lung Screening Trial (NLST) is a randomized multicenter study comparing low-dose helical computed tomography (CT) with chest radiography in the screening of older current and former heavy smokers for early detection of lung cancer, which is the leading cause of cancer-related death in the United States Five-year survival rates approach 70% with surgical resection of stage IA disease; however, more than 75% of individuals have incurable locally advanced or metastatic disease, the latter having a 5-year survival of less than 5% It is plausible that treatment should be more effective and the likelihood of death decreased if asymptomatic lung cancer is detected through screening early enough in its preclinical phase For these reasons, there is intense interest and intuitive appeal in lung cancer screening with low-dose CT The use of survival as the determinant of screening effectiveness is, however, confounded by the well-described biases of lead time, length, and overdiagnosis Despite previous attempts, no test has been shown to reduce lung cancer mortality, an endpoint that circumvents screening biases and provides a definitive measure of benefit when assessed in a randomized controlled trial that enables comparison of mortality rates between screened individuals and a control group that does not undergo the screening intervention of interest The NLST is such a trial The rationale for and design of the NLST are presented

Effect of femoral head size on wear of the polyethylene acetabular component.

Abstract: A technique was developed to determine the wear of the acetabular component of a total hip replacement by examination of standardized initial and follow-up radiographs. Three hundred and eighty-five hips were followed for at least 9.5 years after replacement. The least amount and rate of linear wear were associated with use of a femoral head that had a diameter of twenty-eight millimeters (p less than 0.001). The greatest amount and mean rate of linear wear occurred with twenty-two-millimeter components, but these differences were not statistically significant. The greatest volumetric wear and mean rate rate of volumetric wear were seen with thirty-two-millimeter components (p less than 0.001). A wider radiolucent line in acetabular Zone 1 was associated with use of the thirty-two-millimeter head. The amounts of resorption of the proximal part of the femoral neck and of lysis of the proximal part of the femur both correlated positively with the extent of linear and volumetric wear; this suggests an association between the amount of debris from wear and these changes in the femoral neck and proximal part of the femur.

Martingale-based residuals for survival models

Abstract: SUMMARY Graphical methods based on the analysis of residuals are considered for the setting of the highly-used Cox (1972) regression model and for the Andersen-Gill (1982) generalization of that model. We start with a class of martingale-based residuals as proposed by Barlow & Prentice (1988). These residuals and/or their transforms are useful for investigating the functional form of a covariate, the proportional hazards assumption, the leverage of each subject upon the estimates of 13, and the lack of model fit to a given subject. 1 1. Model Consider a set of n independent subjects such that the counting process Ni {Ni(t), t } O} for the ith subject in the set indicates the number of observed events experienced over time t. The sample paths of the Ni are step functions with jumps of size +1 and with Ni(0) =0. We assume that the intensity function for Ni(t) is given by Yi(t)dA{t, Zi(t)} = Yi(t) eP'Z(t) dAO(t), (1) where Yi(t) is a 0-1 process indicating whether the ith subject is a risk at time t, 13 is a vector of regression coefficients, Zi(t) is a p dimensional vector of covariate processes, and Ao is the baseline cumulative hazard function. Several familar survival models fit into this framework. The Andersen & Gill (1982) generalization of the Cox (1972) model arises when AO(t) is completely unspecified. The further restriction that Yi(t) = 1 until the first event or censoring, and is 0 thereafter yields the Cox model. The parametric form AO(t) = t yields a Poisson model, or an exponential if restricted to a single event per subject, and AO(t) = tP a Weibull model. Our attention will focus primarily on the Andersen-Gill and Cox models; however, the