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Selected AbstractsMultistage designs in the genomic era: Providing balance in complex disease studiesGENETIC EPIDEMIOLOGY, Issue S1 2007Marie-Pierre Dubé Abstract In this summary paper, we describe the contributions included in the Multistage Design group (Group 14) at the Genetic Analysis Workshop 15, which was held during November 12,14, 2006. Our group contrasted and compared different approaches to reducing complexity in a genetic study through implementation of staged designs. Most groups used the simulated dataset (problem 3), which provided ample opportunities for evaluating various staged designs. A wide range of multistage designs that targeted different aspects of complexity were explored. We categorized these approaches as reducing phenotypic complexity, model complexity, analytic complexity or genetic complexity. In general we learned that: (1) when staged designs are carefully planned and implemented, the power loss compared to a single-stage analysis can be minimized and study cost is greatly reduced; (2) a joint analysis of the results from each stage is generally more powerful than treating the second stage as a replication analysis. Genet. Epidemiol. 31 (Suppl. 1):S118,S123, 2007. © 2007 Wiley-Liss, Inc. [source] Parent-of-origin, imprinting, mitochondrial, and X-linked effects in traits related to alcohol dependence: Presentation Group 18 of Genetic Analysis Workshop 14GENETIC EPIDEMIOLOGY, Issue S1 2005Konstantin Strauch Abstract The participants of Presentation Group 18 of Genetic Analysis Workshop 14 analyzed the Collaborative Study on the Genetics of Alcoholism data set to investigate sex-specific effects for phenotypes related to alcohol dependence. In particular, the participants looked at imprinting (which is also known as parent-of-origin effect), differences between recombination fractions for the two sexes, and mitochondrial and X-chromosomal effects. Five of the seven groups employed newly developed or existing methods that take imprinting into account when testing for linkage, or test for imprinting itself. Single-marker and multipoint analyses were performed for microsatellite as well as single-nucleotide polymorphism markers, and several groups used a sex-specific genetic map in addition to a sex-averaged map. Evidence for paternal imprinting (i.e., maternal expression) was consistently obtained by at least two groups at genetic regions on chromosomes 10, 12, and 21 that possibly harbor genes responsible for alcoholism. Evidence for maternal imprinting (which is equivalent to paternal expression) was consistently found at a locus on chromosome 11. Two groups applied extensions of variance components analysis that model a mitochondrial or X-chromosomal effect to latent class variables and electrophysiological traits employed in the diagnosis of alcoholism. The analysis, without using genetic markers, revealed mitochondrial or X-chromosomal effects for several of these traits. Accounting for sex-specific environmental variances appeared to be crucial for the identification of an X-chromosomal factor. In linkage analysis using marker data, modeling a mitochondrial variance component increased the linkage signals obtained for autosomal loci. Genet. Epidemiol. 29(Suppl. 1):S125,S132, 2005. © 2005 Wiley-Liss, Inc. [source] USING INCIDENT LIGHT TO MAXIMIZE RESOLUTION OF STRUCTURE ON DIATOM VALVES WITH A LIGHT MICROSCOPEJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Siver, P. A. Botany Department, Connecticut College, New London, CT 06320 Because of their abundance in a diverse array of aquatic habitats and chemical conditions, and the fact that their species-specific siliceous outer coverings remain for millennia in sediments, diatoms have become one of the most powerful organismal groups used in the reconstruction of historical environmental conditions. Although SEM is now needed to identify some species, the bulk of the identifications and data collection is still accomplished with a light microscope. In this paper I will demonstrate the use of interference reflection contrast (incident light) for the examination of diatoms that significantly improves the resolution of structural detail. Using incident light one can routinely distinguish between structures close to the theoretical limit of resolution for visible light, and about 70 nm closer together than resolvable with standard transmitted light optics. Examples of how the incident light technique can improve data collection with light microscopy will be given. Most research light microscopes could be easily and inexpensively outfitted to use this technique. [source] Divergent synthesis of dendrimer-like macromolecules through a combination of atom transfer radical polymerization and click reactionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2007Qingchun Liu Abstract This article describes a divergent strategy to prepare dendrimer-like macromolecules from vinyl monomers through a combination of atom transfer radical polymerization (ATRP) and click reaction. Firstly, star-shaped polystyrene (PS) with three arms was prepared through ATRP of styrene starting from a three-arm initiator. Next, the terminal bromides of the star-shaped PS were substituted with azido groups. Afterwards, the azido-terminated star-shaped PS was reacted with propargyl 2,2-bis((2,-bromo-2,-methylpropanoyloxy)methyl)propionate (PBMP) via click reaction. Star-shaped PS with six terminal bromide groups was afforded and served as the initiator for the polymerization of styrene to afford the second-generation dendrimer-like PS. Iterative process of the aforementioned sequence of reactions could allow the preparation of the third-generation dendrimer-like PS. When the second-generation dendrimer-like PS with 12 bromide groups used as an initiator for the polymerization of tert -butyl acrylate, the third-generation dendrimer-like block copolymer with a PS core and a poly (tert -butyl acrylate) (PtBA) corona was afforded. Subsequently PtBA segments were selectively hydrolyzed with hydrochloric acid, resulting an amphiphilic branched copolymer with inner dendritic PS and outer linear poly(acrylic acid) (PAA). Following the same polymerization procedures, the dendrimer-like PS and PS- block -PtBA copolymers of second generation originating from six-arm initiator were also synthesized. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3330,3341, 2007 [source] Effects of experimenting with physical and virtual manipulatives on students' conceptual understanding in heat and temperatureJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 9 2008Zacharias C. Zacharia Abstract This study aimed to investigate the comparative value of experimenting with physical manipulatives (PM) in a sequential combination with virtual manipulatives (VM), with the use of PM preceding the use of VM, and of experimenting with PM alone, with respect to changes in students' conceptual understanding in the domain of heat and temperature. A pre,post-comparison study design was used which involved 62 undergraduate students that attended an introductory course in physics. The participants were randomly assigned to one experimental and one control group. Both groups used the same inquiry-oriented curriculum materials. Participants in the control group used PM to conduct the experiments, whereas, participants in the experimental group used first PM and then VM. VM differed from PM in that it could provide the possibility of faster manipulation, whereas, it retained any other features and interactions of the study's subject domain identical to the PM condition. Conceptual tests were administered to assess students' understanding before, during, and after the study's treatments. Results indicated that experimenting with the combination of PM and VM enhanced students' conceptual understanding more than experimenting with PM alone. The use of VM was identified as the cause of this differentiation. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 1021,1035, 2008 [source] Review: Organotin compounds and their therapeutic potential: a report from the Organometallic Chemistry Department of the Free University of Brussels,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2002Marcel Gielen Abstract An overview of the development of antitumour organotin derivatives is presented and discussed for selected classes of compounds, such as tetraorganodicarboxylatodistannoxanes and related diorganotin dicarboxylates, and for triorganotin carboxylates. Among the carboxylate groups used are steroidcarboxylates and other biologically relevant carboxylates. High to very high in vitro activities have been found, sometimes equalling that of doxorubicin. Solubility in water is an important issue, dominating the in vivo testing of compounds. Polar substituents, like fluorine or polyoxaalkyl moieties, improve the water solubility. Although organotin derivatives constitute a separate class of compounds, the comparison with cisplatin is inevitable. Among the observed toxicities, neurotoxicity, known from platinum cytostatics, and gastrointestinal toxicity, typical for many oncology drugs, have been detected, but to a lower extent. Further research to develop novel useful organotin antitumour compounds needs to be carried out. Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparison of Adverse Events during Procedural Sedation between Specially Trained Pediatric Residents and Pediatric Emergency Physicians in IsraelACADEMIC EMERGENCY MEDICINE, Issue 7 2008Itai Shavit MD Abstract Objectives:, The aim was to compare the rate of procedural sedation,related adverse events of pediatric residents with specific training in "patient safety during sedation" and pediatric emergency physicians (PEPs) who completed the same course or were teaching faculty for it. Methods:, This prospective single-blinded, nonrandomized study was conducted in two university-affiliated pediatric emergency departments (PEDs) in Israel. Pediatric residents who were authorized to perform unsupervised sedations had previously completed a course in patient safety during sedation. Unsupervised sedations by residents were defined as sedations where the entire procedure was performed independently. Study subjects had autonomy in choosing medications for sedation. Adverse events were defined as transient hypoxia (oxygen saturation , 90%) or apnea. Adverse outcomes were situations where intubation or hospitalization directly related to sedation complications would occur. Sedations over 12 consecutive months were recorded, and rates of adverse events in each group were compared. Results:, A total of 984 eligible sedations were recorded, 635 by unsupervised residents and 349 by PEPs. A total of 512 (80.6%) sedations were performed by residents when attending physicians were not in the ED. The total adverse event rate was 24/984 (2.44%). When the two groups used a similar type drugs, residents had 8/635 (1.26%) events, compared to 11/328 (3.35%) by PEPs. There was no statistically significant difference in the rates of hypoxia or apnea between the two groups (p = 0.29 and p = 0.18, respectively). Adverse outcomes did not occur. Conclusions:, Unsupervised pediatric residents with training in patient safety during sedation performed procedural sedations with a rate of adverse events similar to that of PEPs. [source] | ||||||||||