Robust and efficient estimation of nonparametric generalized linear models.

Unlabelled: Generalized linear models are flexible tools for the analysis of diverse datasets, but the classical formulation requires that the parametric component is correctly specified and the data contain no atypical observations. To address these shortcomings, we introduce and study a family of nonparametric full-rank and lower-rank spline estimators that result from the minimization of a penalized density power divergence. The proposed class of estimators is easily implementable, offers high protection against outlying observations and can be tuned for arbitrarily high efficiency in the case of clean data.

RNA biomarkers from proximal liquid biopsy for diagnosis of ovarian cancer.

Background: Most ovarian cancer patients are diagnosed at an advanced stage and have a high mortality rate. Current screening strategies fail to improve prognosis because markers that are sensitive for early stage disease are lacking. This medical need justifies the search for novel approaches using utero-tubal lavage as a proximal liquid biopsy.

Outlier robust modeling of survival curves in the presence of potentially time-varying coefficients.

In time to event studies, censoring often occurs and models that take this into account are wide-spread. In the presence of outliers, standard estimators of model parameters may be affected such that results and conclusions are not reliable anymore. This in turn also hampers the detection of these outliers due to masking effects.

Melanoma addiction to the long non-coding RNA SAMMSON.

Focal amplifications of chromosome 3p13-3p14 occur in about 10% of melanomas and are associated with a poor prognosis. The melanoma-specific oncogene MITF resides at the epicentre of this amplicon. However, whether other loci present in this amplicon also contribute to melanomagenesis is unknown.

Mathematical inference on helminth egg counts in stool and its applications in mass drug administration programmes to control soil-transmitted helminthiasis in public health.

In the present study, we present a hierarchical model based on faecal egg counts (FECs; expressed in eggs per 1g of stool) in which we first describe the variation in FECs between individuals in a particular population, followed by describing the variance due to counting eggs under a microscope separately for each stool sample. From this general framework, we discuss how to calculate a sample size for assessing a population mean FEC and the impact of an intervention, measured as reduction in FECs, for any scenario of soil-transmitted helminth (STH) epidemiology (the intensity and aggregation of FECs within a population) and diagnostic strategy (amount of stool examined (∼sensitivity of the diagnostic technique) and examination of individual/pooled stool samples) and on how to estimate prevalence of STH in the absence of a gold standard. To give these applications the most wide relevance as possible, we illustrate each of them with hypothetical examples.

A statistical basis for harmonization of thyroid stimulating hormone immunoassays using a robust factor analysis model.

Background: Between-method equivalence ideally is achieved by calibration against an SI-traceable reference measurement procedure. For measurement of thyroid stimulating hormone (TSH), it is unlikely to accomplish this goal in mid-term. Therefore, we investigated a statistical alternative based on a factor analysis (FA) model.

Simulation of between repeat variability in real time PCR reactions.

While many decisions rely on real time quantitative PCR (qPCR) analysis few attempts have hitherto been made to quantify bounds of precision accounting for the various sources of variation involved in the measurement process. Besides influences of more obvious factors such as camera noise and pipetting variation, changing efficiencies within and between reactions affect PCR results to a degree which is not fully recognized. Here, we develop a statistical framework that models measurement error and other sources of variation as they contribute to fluorescence observations during the amplification process and to derived parameter estimates.

Xenotransplantation by injection of a suspension of isolated preantral ovarian follicles and stroma cells under the kidney capsule of nude mice.

Objective: To develop and test a novel approach to xenotransplantation of isolated preantral follicles underneath the kidney capsule of immunodeficient mice.

Design: Prospective experimental animal study.

Setting: Academic research unit.

Follicle survival and growth to antral stages in short-term murine ovarian cortical transplants after Cryologic solid surface vitrification or slow-rate freezing.

This study was designed to asses murine preantral follicle survival and growth, after cryopreservation of ovarian tissue by two different methodologies, solid-surface vitrification by the Cryologic vitrification method (CVM) and slow-rate freezing (SRF). Cryotreated tissue was stored in liquid nitrogen for 24h, and upon warming follicle viability was assessed by live/dead fluorescent probes, and by 7-day autotransplantation of both cryotreated tissue types to the left and right kidney capsule of the donor animals (n=16). The live/dead assay immediately upon tissue warming did not allow a distinction to be made in terms of follicle viability between the CVM and SRF cryoprocedure.

Lack of fluorophotometric evidence of aqueous-vitreous barrier disruption after posterior capsulorhexis.

Purpose: To evaluate the integrity of the aqueous-vitreous barrier by assessing the flow of fluorescein from the anterior chamber to the anterior vitreous using fluorophotometry in eyes with a posterior continuous curvilinear capsulorhexis (PCCC) and in eyes without a PCCC.

Setting: University Hospital Antwerp, Edegem, Belgium.

Methods: Ten patients had bilateral extracapsular cataract extraction with implantation of an intraocular lens.