Meiotic cellular rejuvenation is coupled to nuclear remodeling in budding yeast.

Production of healthy gametes in meiosis relies on the quality control and proper distribution of both nuclear and cytoplasmic contents. Meiotic differentiation naturally eliminates age-induced cellular damage by an unknown mechanism. Using time-lapse fluorescence microscopy in budding yeast, we found that nuclear senescence factors - including protein aggregates, extrachromosomal ribosomal DNA circles, and abnormal nucleolar material - are sequestered away from chromosomes during meiosis II and subsequently eliminated. A similar sequestration and elimination process occurs for the core subunits of the nuclear pore complex in both young and aged cells. Nuclear envelope remodeling drives the formation of a membranous compartment containing the sequestered material. Importantly, de novo generation of plasma membrane is required for the sequestration event, preventing the inheritance of long-lived nucleoporins and senescence factors into the newly formed gametes. Our study uncovers a new mechanism of nuclear quality control and provides insight into its function in meiotic cellular rejuvenation

Progestogens to prevent preterm birth in twin pregnancies: an individual participant data meta-analysis of randomized trials

<p>Abstract</p> <p>Background</p> <p>Preterm birth is the principal factor contributing to adverse outcomes in multiple pregnancies. Randomized controlled trials of progestogens to prevent preterm birth in twin pregnancies have shown no clear benefits. However, individual studies have not had sufficient power to evaluate potential benefits in women at particular high risk of early delivery (for example, women with a previous preterm birth or short cervix) or to determine adverse effects for rare outcomes such as intrauterine death.</p> <p>Methods/design</p> <p>We propose an individual participant data meta-analysis of high quality randomized, double-blind, placebo-controlled trials of progestogen treatment in women with a twin pregnancy. The primary outcome will be adverse perinatal outcome (a composite measure of perinatal mortality and significant neonatal morbidity). Missing data will be imputed within each original study, before data of the individual studies are pooled. The effects of 17-hydroxyprogesterone caproate or vaginal progesterone treatment in women with twin pregnancies will be estimated by means of a random effects log-binomial model. Analyses will be adjusted for variables used in stratified randomization as appropriate. Pre-specified subgroup analysis will be performed to explore the effect of progestogen treatment in high-risk groups.</p> <p>Discussion</p> <p>Combining individual patient data from different randomized trials has potential to provide valuable, clinically useful information regarding the benefits and potential harms of progestogens in women with twin pregnancy overall and in relevant subgroups.</p

Early Treatment Of Anterıor Cross-Bıte: A Case Report

Anterior crossbite can be a result of skeletal, functional or dental disharmony of the the orthognathic system. Removable and fixed appliances are widely used methods to correct them. In the current study, 4 cases having anterior cross bite have been presented which were treated by Class III activator, anterior inclined bite plate, chin cap and 2 by 4 fixed mechanics. Anterior crossbite was corrected successfully by using these appliances and the results achieved have been presented

Risk tolerance measure for decision-making in fuzzy analysis: a health risk assessment perspective

In risk assessment studies it is important to determine how uncertain and imprecise knowledge should be included into the simulation and assessment models. Thus, proper evaluation of uncertainties has become a major concern in environmental and health risk assessment studies. Previously, researchers have used probability theory, more commonly Monte Carlo analysis, to incorporate uncertainty analysis in health risk assessment studies. However, in conducting probabilistic health risk assessment, risk analyst often suffers from lack of data or the presence of imperfect or incomplete knowledge about the process modeled and also the process parameters. Fuzzy set theory is a tool that has been used in propagating imperfect and incomplete information in health risk assessment studies. Such analysis result in fuzzy risks which are associated with membership functions. Since possibilistic health risk assessment studies are relatively new, standard procedures for decision-making about the acceptability of the resulting fuzzy risk with respect to a crisp standard set by the regulatory agency are not fully established. In this paper, we are providing a review of several available approaches which may be used in decision-making. These approaches involve defuzzification techniques, the possibility and the necessity measures. In this study, we also propose a new measure, the risk tolerance measure, which can be used in decision making. The risk tolerance measure provides an effective metric for evaluating the acceptability of a fuzzy risk with respect to a crisp compliance criterion. Fuzzy risks with different membership functions are evaluated with respect to a crisp compliance criterion by using the possibility, the necessity, and the risk tolerance measures and the results are discussed comparatively

Fuzzy Multiobjective Decision Making Approach for Groundwater Resources Management

A conventional simulation-optimization model with constraint on drawdown at an area of interest is used to optimize additional groundwater withdrawal at multiple demand locations in a coastal aquifer. After obtaining the optimal solution, a decision-making analysis is conducted using fuzzy logic concepts. The goal is to evaluate multiple objectives and select the best management strategy. This methodology is applied to a hypothetical case consisting of six groundwater demand locations in Savannah, Ga. The objective function of the optimization model includes a penalty term which can be adjusted by the user to control the degree of "fairness" with respect to the distribution of limited groundwater resources in the region. The decision-making framework incorporates hydrologically, politically, and economically motivated multiple conflicting objectives into the evaluation process. Results of the coupled simulation-optimization model are used to determine individual satisfaction degrees of each management strategy with respect to multiple objectives. Based on this outcome, an overall performance value is calculated by using the ordered weighted averaging (OWA) operator and the management strategy with the highest overall performance is identified as the best strategy. The OWA operator is an averaging operator that avoids ruling out some alternatives in favor of others which is observed in the logical operators such as "and" and "or." When combined with expert knowledge to identify the appropriate membership functions for the fuzzy objectives, the procedure developed in this study may yield transparent and robust groundwater management solutions in coastal aquifers

Attitudes of Turkish Medical and Law Students towards the Organ Donation

Background: Attitudes of medical and law personnel towards organ donation are very important