bluuebunny/crossref_metadata_2025 huggingface dataset:
MRI of chondromyxoid fibroma
Authors: Kim Hyun-Soo , Jee Won-Hee , Ryu Kyung-Nam , Cho Kil-Ho , Suh Jin-Suck , Cho Jae-Hyun , Choi Yun-Sun , Lee Sung Moon , Lee Jong-Min , Sung Mi Sook , Kim Jee Young , Jung Eun Sun , Chung Yang-Guk , Ok In-Young
Published: August 2011

Background

Chondromyxoid fibroma is a rare benign primary bone tumor of cartilage. Despite a characteristic radiographic appearance, chondromyxoid fibroma with atypical radiographic findings may mimic more common tumors.

Purpose

To describe the MR findings of chondromyxoid fibroma.

Material and Methods

MR images of 19 histopathologically confirmed chondromyxoid fibromas were retrospectively analyzed for signal intensity, periosteal reaction, adjacent abnormal bone marrow and soft tissue signal, and patterns of contrast enhancement.

Results

All cases of chondromyxoid fibroma showed hypointense to intermediate signal intensity and internal hyperintense foci were observed in seven (37%) cases on T1-weighted images. On T2-weighted images, all lesions were hyperintense: peripheral intermediate signal band with central hyperintense signal in 11 (58%) of 19 lesions, whereas diffusely hyperintense with heterogeneous pattern in eight (42%). Periosteal reaction was observed in 11 (58%) of 19 cases. Adjacent abnormal bone marrow or soft tissue signal was observed in 12 (63%) or 14 (74%) of 19 cases, respectively. On contrast-enhanced T1-weighted images, peripheral nodular enhancement was observed in 69% (11/16) and diffuse contrast enhancement was observed in 31% (5/16) with homogeneous ( n = 3) or heterogeneous ( n = 2) patterns. Among the cases with peripheral nodular enhancement, the peripheral nodular enhancing portion generally corresponded to the peripheral intermediate signal band on T2-weighted images, although the peripheral enhancement was not as wide as a band of intermediate signal intensity. On the other hand, the central non-enhancing portion generally corresponded to the central hyperintense signal intensity on T2-weighted images.

Conclusion

The helpful features of chondromyxoid fibroma are the peripheral intermediate signal band and central hyperintense signal on T2-weighted images, generally corresponding to the peripheral nodular enhancement and central non-enhancing portion on contrast-enhanced T1-weighted images, respectively.
The relationship between office system tools and evidence-based care in primary care physician practice
Authors: Davis Mark A , Pavur Robert J
Published: August 2011

A number of office system tools have been developed to improve the rates of preventive services and enhance the quality of medical care in practice settings. New approaches to measuring physician adherence to evidence-based standards of treatment, offer a unique opportunity to examine the link between the use of office system tools and evidence-based practices in primary care. Using episode-based profiling measures of adherence as the criterion, results from this investigation suggest that the application of simple physician reminders can be an effective technique for promoting evidence-based treatment. The data also reveal that the influence of health information technology (HIT) resources on adherence was not exclusively positive. Specifically, adherence to evidence-based standards was higher for primary care practices that employed HIT resources judiciously. In contrast, extensive use of personal digital assistants was negatively associated with adherence. Despite concerns directed towards the new generation of episode-based profiling measures, results from this research indicate that the measures behave similarly to traditional measures of quality.
Strategic groups in health care: a literature review
Authors: Perryman Martha M , Rivers Patrick A
Published: August 2011

The purpose of this study is to review the literature that discusses the relationship between strategic group membership and performance in the nursing home industry. This literature review examines the relationship between organizational structure and performance in the nursing home industry. Results from these studies suggest industry stability of segmentation; limitation of strategic choice due to high mobility barriers (as represented by facility, staffing and location variables); quality is controlled by the existing combinations of industry regulation and market competition; and the existence of performance differences among strategic groups.
An empirical investigation into health sector absenteeism
Authors: Walker Vivienne , Bamford David
Published: August 2011

The purpose of this research was to consider why absenteeism in Health and Social Care is so high and to suggest proactive changes in organization activity to address this. The research took a multimethod approach with a quantitative emphasis; there were three parts: (i) quantitative survey questionnaire; (ii) analysis of absenteeism and related secondary data; and (iii) qualitative data from other questions in survey and discussion groups. The quantitative emphasis in the research is appropriate, given the gap identified in the literature. Perceived limitations are that the study considers just one part of the overall system. The research indicates that managers underestimate staff absence levels and almost half believe absenteeism cannot reduce. Professional managers were more negative and over half of nurse managers believed that absence could not reduce. Unless there is a systematic systemic change in organizations, which changes managers' attitudes and understanding of absence with a consequent change in activity across the absence continuum, there is no prospect of a sustained reduction in absence levels. Manager impact and role in absence management are poorly covered in research, so this research helps inform those gaps.
Medical engagement: a crucial underpinning to organizational performance
Authors: Spurgeon Peter , Mazelan Patti M , Barwell Fred
Published: August 2011

Medical Engagement has long been advocated as a critical component relating to organizational performance. Relatively little data though existed to support this contention. Using the Medical Engagement Scale (MES) This study demonstrates a persuasive linkage between assessed levels of Medical Engagement in secondary care organizations and independently gathered performance measures. Implications of executive leaders in promoting engagement are explored.
How and when service quality and satisfaction simultaneously influence purchase intentions?
Authors: Huang Yu-Ying , Li Shyh-Jane , Yang Miles M
Published: August 2011

Th e purpose of this study is to examine how and when service quality and satisfaction simultaneously influence purchase intentions. The study tries to explore and clarify the relationship between service quality and satisfaction, and to examine whether satisfaction simultaneously moderates and mediates the relationship between perceived service quality and purchase intentions. A field survey was conducted for the outpatients of 12 regional hospitals in Taiwan. The findings show that the effects of different dimensions of service quality on purchase intentions are not equal across satisfied and unsatisfied patients. This study provides empirical evidence that show how the dual roles of the moderator and mediator manipulated together by satisfaction, work to affect purchase intentions in hospital settings. In addition, the relationships between service quality and satisfaction are also clarified.
2009–2010 ISMS-MSI Practice Prize Competition—Special Section Introduction
Authors: Winer Russell S.
Published: August 2011

I introduce the work of the finalists in the 2009–2010 ISMS-MSI Practice Prize Competition, representing once again the best combinations of rigor and relevance produced by marketing scientists. The winning paper is by a team from several German universities and represents a collaboration with Bayer AG on an important problem—allocating the marketing budget dynamically across countries, products, and the marketing mix. The other three finalists described projects involving a branding project for an Australian airline, Jetstar, based on a dynamic choice model; a new tool for differentiating Prudential's variable annuities from the competition; and a marketing communications model for a small, family-run European office furniture supplier, Inofec.
Integrated Product Architecture and Pricing for Managing Sequential Innovation
Authors: Krishnan Vish , Ramachandran Karthik
Published: August 2011

Science and technology advances drive firms to continually enhance their product's performance and launch sequentially improving offerings. Firms face challenges in marketing such improving products to well-informed, forward-looking consumers who anticipate product improvements and seek to delay their purchase timing. Product design, specifically a modular upgradable architecture in which improving and stable subsystems of a product are separated and selectively upgraded, can be a valuable approach for marketers to alleviate consumer concerns about product obsolescence. However, such an architecture-based approach can present new challenges as well, and dealing with them requires carefully coordinated cross-functional decision making by the firm. In this paper, we identify and formalize the notion of design inconsistency, which refers to the monopolist firm's inability to commit to future product design architectures. We find that firms experience design inconsistency even when they are able to commit to future prices, and design inconsistency lowers firm profits as well as consumer surplus. We then derive a joint product architecture and pricing approach to solve this problem; this enables an innovating firm to optimally and in a time-consistent manner launch modular upgradable products. The modeling and analysis in the paper lends insight into types of markets and products for which modular upgradability is most appropriate and offers guidelines on making pricing and product design decisions jointly for managing sequential innovation.

This paper was accepted by Preyas Desai, marketing.
Stochastic Capacity Investment and Flexible vs. Dedicated Technology Choice in Imperfect Capital Markets
Authors: Boyabatlı Onur , Toktay L. Beril
Published: August 2011

This paper analyzes the impact of endogenous credit terms under capital market imperfections in a capacity investment setting. We model a monopolist firm that decides on its technology choice (flexible versus dedicated) and capacity level under demand uncertainty. Differing from the majority of the stochastic capacity investment literature, we assume that the firm is budget constrained and can relax its budget constraint by borrowing from a creditor. The creditor offers technology-specific loan contracts to the firm, after which the firm makes its technology choice and subsequent decisions. Capital market imperfections impose financing frictions on the firm. Our analysis contributes to the capacity investment literature by extending the theory of stochastic capacity investment and flexible versus dedicated technology choice to understand the impact of capital market imperfections, and by analyzing the impact of demand uncertainty (variability and correlation) on the operational decisions and the performance of the firm under different capital market conditions. We demonstrate that the endogenous nature of credit terms in imperfect capital markets may modify or reverse conclusions concerning capacity investment and technology choice obtained under the perfect market assumption and we explain why. The theory developed in this paper suggests some rules of thumb for the strategic management of the capacity and technology choice in imperfect capital markets.

This paper was accepted by John Birge, focused issue editor.
Effects of Non-Indigenous Australian Human Resource Managers' Gender and Attitudes and Applicants' Ethnicity and Gender on Resumé Evaluations
Authors: Hughes Lauren , Davidson Graham R.
Published: August 2011

In this web-based survey, 60 non-Indigenous Australian human resource (HR) professionals reviewed four fictitious job resumés for an Indigenous male, Indigenous female, non-Indigenous male and non-Indigenous female. Participants rated the resumés against five key selection criteria and then ranked them in terms of suitability for a HR position, team fit (TF) with participants' current HR team, and suitability for a customer service (CS) position. Finally, participants completed a modified Attitude toward Indigenous Australians scale. Although participants' gender and attitudes and applicants' gender and ethnicity did not have an effect on resumé ratings, rank differences for the HR position and TF for the whole sample were significantly different, with the non-Indigenous male applicant being preferred to the Indigenous male and female applicants. Participants holding a negative attitude toward Indigenous people consistently ranked the non-Indigenous male applicant more favourably than the Indigenous male and female applicants and the non-Indigenous female applicant more favourably than the Indigenous male applicant. Female participants ranked the non-Indigenous male applicant more favourably than the Indigenous male and female applicants for the HR position and TF. Implications for Indigenous Australian employment disadvantage are examined with reference to social identity and contemporary racism theories.
The Relationship Between Communication Climate and Elementary Teachers' Beliefs About Alternative Assessment
Authors: Lee Seungcheol Austin , Park Hee Sun , Choi Jinyoung
Published: August 2011

Alternative assessment in education is becoming widely implemented around the Pacific region. This study conducted a multilevel analysis of communication climate and beliefs about the effectiveness of alternative assessment. Participants were 662 teachers from 75 elementary schools in Korea. The findings showed that teachers' beliefs about the effectiveness of alternative assessment were positively influenced by their perception of communication climate at their schools and their perception of support from principals, peer teachers, students and parents. The effect of teachers' endorsement of textbook-based learning was moderated by school-level communication climate. The findings indicated that an open communication climate at schools is a key for the successful implementation of alternative assessment.
Newspaper Reports Constructing Allegations and Responsibilities in the Pitcairn Island Sexual Abuse Trials
Authors: Tuffin Keith , Simons Melanie
Published: August 2011

The Pitcairn sexual abuse trial was widely reported in New Zealand newspapers and this study examines constructions of both allegations and explanations of sexual abuse. Discourse analysis was used to study a database of 76 reports from the Dominion Post and New Zealand Herald. The analysis identified three discourses that co-articulate allegations of sexual abuse and attempts to explain and account for these allegations. The first discourse deals with reported allegations of childhood sexual abuse and trauma. The second discourse deflects responsibility from the accused men and lays open explanations drawing on the history and culture of Pitcairn. The third discourse constructs abuse as something that occurred because Britain failed to meet its responsibilities and provide adequate legal and moral guidance. These discourses are discussed in terms of the actions they perform in terms of reducing the level of personal responsibility for crimes of sexual abuse.
Effectiveness of a School-Based Indicated Early Intervention Program for Māori and Pacific Adolescents
Authors: Woods Barbara , Jose Paul E.
Published: August 2011

This study set out to determine the efficacy of a school-based early intervention program (the Kiwi ACE program) with Māori and Pacific adolescents experiencing depressive symptoms. A large group ( N = 419) of Māori and Pacific students (average age 14 years) was screened for depressive symptoms and, from a pool of students scoring greater than 63 on the Children's Depression Inventory (CDI), 56 students were randomly assigned to either an intervention or control group. After attrition, the final sample constituted 24 young people after one year. The intervention comprised eight 90-minute sessions conducted in school time. Students were taught to more fully understand the relationships between thinking, feeling and behaviour, to challenge beliefs and to solve interpersonal problems. At immediate posttest ( p = .045) and at one-year follow-up ( p < .001) a significant effect for condition was obtained: the intervention group reported lower depressive symptoms. Efficacy of the intervention was supported by qualitative data obtained from focus groups. Further controlled trials on a larger scale are recommended to establish the durability and generalisability of the effects of program participation.
Vom Katalogzettel zum IPAC, vom IPAC zum OPAC. Ein Projekt der UB Frankfurt zur automatisierten Konversion digitalisierter Zettelkataloge
Authors: Hausinger Angela , Junkes-Kirchen Klaus , Dinges Ingrid , Hamann Sylvia , Schneider Hanspeter , Steinberg Sylvia , Wahlig Renate
Published: August 2011

Beschrieben wird ein Projekt, das an der Universitätsbibliothek Frankfurt am Main gemeinsam mit dem HeBIS-Verbund und der Firma Satzrechenzentrum (Berlin) durchgeführt wurde. Ziel war es, bereits digitalisierte Zettelkataloge mit Hilfe automatisierter Verfahren in strukturierte MAB-Daten zu konvertieren, die in die Verbunddatenbank eingespielt werden können. Von der Größenordnung her sollten 2,7 Mio. gescannte Katalogzettel dabei durch entsprechende Algorithmen bearbeitet werden. Als Ergebnis kann vorweg genommen werden, dass nach einer intensiveren Vorbereitungsphase die Umsetzung der Titelkarten durch Programmroutinen ein sehr passables Ergebnis erbrachte.
On the mutual position of two irreducible conics in PG(2, q), q odd
Authors: Abatangelo V. , Fisher J. C. , Korchmáros G. , Larato B.
Published: August 2011

Given an irreducible conic in PG(2, q) with q odd, how many points of another irreducible conic 𝒟 in PG(2, q) are external to ? It is not hard to find 𝒟 such that either all its points off are external to , or none of its points are. Apart from these cases, we prove that for q large enough, the number we seek differs from by at most .
Structures and mechanism of the monoamine oxidase family
Authors: Gaweska Helena , Fitzpatrick Paul F.
Published: August 2011

Members of the monoamine oxidase family of flavoproteins catalyze the oxidation of primary and secondary amines, polyamines, amino acids, and methylated lysine side chains in proteins. The enzymes have similar overall structures, with conserved flavin adenine dinucleotide (FAD)-binding domains and varied substrate-binding sites. Multiple mechanisms have been proposed for the catalytic reactions of these enzymes. The present review compares the structures of different members of the family and the various mechanistic proposals.
Sex differences in the injured brain
Authors: Melcangi Roberto Cosimo , Garcia-Segura Luis M.
Published: August 2011

Observations obtained in human and in experimental models clearly demonstrate sex differences in degenerative events occurring in the central nervous system. The present review focuses on potential factors that may contribute to these sex-dimorphic features; in particular, morphological organization of the central nervous system and functional influence by neuroactive steroids, genes, and immune system are considered.
A New Method to Uncover Signatures of Divergent and Stabilizing Selection in Quantitative Traits
Authors: Ovaskainen Otso , Karhunen Markku , Zheng Chaozhi , Arias José Manuel Cano , Merilä Juha
Published: August 2011

While it is well understood that the pace of evolution depends on the interplay between natural selection, random genetic drift, mutation, and gene flow, it is not always easy to disentangle the relative roles of these factors with data from natural populations. One popular approach to infer whether the observed degree of population differentiation has been influenced by local adaptation is the comparison of neutral marker gene differentiation (as reflected in FST) and quantitative trait divergence (as reflected in QST). However, this method may lead to compromised statistical power, because FST and QST are summary statistics which neglect information on specific pairs of populations, and because current multivariate tests of neutrality involve an averaging procedure over the traits. Further, most FST–QST comparisons actually replace QST by its expectation over the evolutionary process and are thus theoretically flawed. To overcome these caveats, we derived the statistical distribution of population means generated by random genetic drift and used the probability density of this distribution to test whether the observed pattern could be generated by drift alone. We show that our method can differentiate between genetic drift and selection as a cause of population differentiation even in cases with FST = QST and demonstrate with simulated data that it disentangles drift from selection more accurately than conventional FST–QST tests especially when data sets are small.
Distribution of Parental Genome Blocks in Recombinant Inbred Lines
Authors: Martin Olivier C , Hospital Frédéric
Published: August 2011

We consider recombinant inbred lines obtained by crossing two given homozygous parents and then applying multiple generations of self-crossings or full-sib matings. The chromosomal content of any such line forms a mosaic of blocks, each alternatively inherited identically by descent from one of the parents. Quantifying the statistical properties of such mosaic genomes has remained an open challenge for many years. Here, we solve this problem by taking a continuous chromosome picture and assuming crossovers to be noninterfering. Using a continuous-time random walk framework and Markov chain theory, we determine the statistical properties of these identical-by-descent blocks. We find that successive block lengths are only very slightly correlated. Furthermore, the blocks on the ends of chromosomes are larger on average than the others, a feature understandable from the nonexponential distribution of block lengths.
The Response of Caenorhabditis elegans to Hydrogen Sulfide and Hydrogen Cyanide
Authors: Budde Mark W , Roth Mark B
Published: August 2011

Hydrogen sulfide (H2S), an endogenously produced small molecule, protects animals from various stresses. Recent studies demonstrate that animals exposed to H2S are long lived, resistant to hypoxia, and resistant to ischemia–reperfusion injury. We performed a forward genetic screen to gain insights into the molecular mechanisms Caenorhabditis elegans uses to appropriately respond to H2S. At least two distinct pathways appear to be important for this response, including the H2S-oxidation pathway and the hydrogen cyanide (HCN)-assimilation pathway. The H2S-oxidation pathway requires two distinct enzymes important for the oxidation of H2S: the sulfide:quinone reductase sqrd-1 and the dioxygenase ethe-1. The HCN-assimilation pathway requires the cysteine synthase homologs cysl-1 and cysl-2. A low dose of either H2S or HCN can activate hypoxia-inducible factor 1 (HIF-1), which is required for C. elegans to respond to either gas. sqrd-1 and cysl-2 represent the entry points in the H2S-oxidation and HCN-assimilation pathways, respectively, and expression of both of these enzymes is highly induced by HIF-1 in response to both H2S and HCN. In addition to their role in appropriately responding to H2S and HCN, we found that cysl-1 and cysl-2 are both essential mediators of innate immunity against fast paralytic killing by Pseudomonas. Furthermore, in agreement with these data, we showed that growing worms in the presence of H2S is sufficient to confer resistance to Pseudomonas fast paralytic killing. Our results suggest the hypoxia-independent hif-1 response in C. elegans evolved to respond to the naturally occurring small molecules H2S and HCN.
Bayesian Population Genomic Inference of Crossing Over and Gene Conversion
Authors: Padhukasahasram Badri , Rannala Bruce
Published: August 2011

Meiotic recombination is a fundamental cellular mechanism in sexually reproducing organisms and its different forms, crossing over and gene conversion both play an important role in shaping genetic variation in populations. Here, we describe a coalescent-based full-likelihood Markov chain Monte Carlo (MCMC) method for jointly estimating the crossing-over, gene-conversion, and mean tract length parameters from population genomic data under a Bayesian framework. Although computationally more expensive than methods that use approximate likelihoods, the relative efficiency of our method is expected to be optimal in theory. Furthermore, it is also possible to obtain a posterior sample of genealogies for the data using this method. We first check the performance of the new method on simulated data and verify its correctness. We also extend the method for inference under models with variable gene-conversion and crossing-over rates and demonstrate its ability to identify recombination hotspots. Then, we apply the method to two empirical data sets that were sequenced in the telomeric regions of the X chromosome of Drosophila melanogaster. Our results indicate that gene conversion occurs more frequently than crossing over in the su-w and su-s gene sequences while the local rates of crossing over as inferred by our program are not low. The mean tract lengths for gene-conversion events are estimated to be ∼70 bp and 430 bp, respectively, for these data sets. Finally, we discuss ideas and optimizations for reducing the execution time of our algorithm.
A Modifier Gene Alleviates Hypothyroidism-Induced Hearing Impairment in Pou1f1dw Dwarf Mice
Authors: Fang Qing , Longo-Guess Chantal , Gagnon Leona H , Mortensen Amanda H , Dolan David F , Camper Sally A , Johnson Kenneth R
Published: August 2011

Thyroid hormone has pleiotropic effects on cochlear development, and genomic variation influences the severity of associated hearing deficits. DW/J-Pou1f1dw/dw mutant mice lack pituitary thyrotropin, which causes severe thyroid hormone deficiency and profound hearing impairment. To assess the genetic complexity of protective effects on hypothyroidism-induced hearing impairment, an F1 intercross was generated between DW/J-Pou1f1dw/+ carriers and an inbred strain with excellent hearing derived from Mus castaneus, CAST/EiJ. Approximately 24% of the (DW/J × CAST/EiJ) Pou1f1dw/dw F2 progeny had normal hearing. A genome scan revealed a locus on chromosome 2, named modifier of dw hearing, or Mdwh, that rescues hearing despite persistent hypothyroidism. This chromosomal region contains the modifier of tubby hearing 1 (Moth1) locus that encodes a protective allele of the microtubule-associated protein MTAP1A. DW/J-Pou1f1dw/+ carriers were crossed with the AKR strain, which also carries a protective allele of Mtap1a, and we found that AKR is not protective for hearing in the (DW/J × AKR) Pou1f1dw/dw F2 progeny. Thus, protective alleles of Mtap1a are not sufficient to rescue DW/J-Pou1f1dw/dw hearing. We expect that identification of protective modifiers will enhance our understanding of the mechanisms of hypothyroidism-induced hearing impairment.
Inference of Population Mutation Rate and Detection of Segregating Sites from Next-Generation Sequence Data
Authors: Kang Chul Joo , Marjoram Paul
Published: August 2011

We live in an age in which our ability to collect large amounts of genome-wide genetic variation data offers the promise of providing the key to the understanding and treatment of genetic diseases. Over the next few years this effort will be spearheaded by so-called next-generation sequencing technologies, which provide vast amounts of short-read sequence data at relatively low cost. This technology is often used to detect unknown variation in regions that have been linked with a given disease or phenotype. However, error rates are significant, leading to some nontrivial issues when it comes to interpreting the data. In this article, we present a method with which to address questions of widespread interest: calling variants and estimating the population mutation rate. We show performance of the method using simulation studies before applying our approach to an analysis of data from the 1000 Genomes project.
Parallel Evolution of Bacillus thuringiensis Toxin Resistance in Lepidoptera
Authors: Baxter Simon W , Badenes-Pérez Francisco R , Morrison Anna , Vogel Heiko , Crickmore Neil , Kain Wendy , Wang Ping , Heckel David G , Jiggins Chris D
Published: August 2011

Despite the prominent and worldwide use of Bacillus thuringiensis (Bt) insecticidal toxins in agriculture, knowledge of the mechanism by which they kill pests remains incomplete. Here we report genetic mapping of a membrane transporter (ABCC2) to a locus controlling Bt Cry1Ac toxin resistance in two lepidopterans, implying that this protein plays a critical role in Bt function.
Exploiting Spore-Autonomous Fluorescent Protein Expression to Quantify Meiotic Chromosome Behaviors in Saccharomyces cerevisiae
Authors: Thacker Drew , Lam Isabel , Knop Michael , Keeney Scott
Published: August 2011

The budding yeast Saccharomyces cerevisiae has proven to be a rich source of information about the mechanisms and regulation of homologous recombination during meiosis. A common technique for studying this process involves microdissecting the four products (ascospores) of a single meiosis and analyzing the configuration of genetic markers in the spores that are viable. Although this type of analysis is powerful, it can be laborious and time-consuming to characterize the large numbers of meioses needed to generate statistically robust data sets. Moreover, the reliance on viable (euploid) spores has the potential to introduce selection bias, especially when analyzing mutants with elevated frequencies of meiotic chromosome missegregation. To overcome these limitations, we developed a versatile, portable set of reporter constructs that drive fluorescent protein expression specifically in only those spores that inherit the reporter. These spore-autonomous fluorescence constructs allow direct visualization of inheritance patterns in intact tetrads, eliminating the need for microdissection and permitting meiotic segregation patterns to be ascertained even in aneuploid spores. As proof of principle, we demonstrate how different arrangements of reporters can be used to quantify crossover frequency, crossover interference, gene conversion, crossover/noncrossover ratios, and chromosome missegregation.
Environmental Memory from a Circadian Oscillator: The Arabidopsis thaliana Clock Differentially Integrates Perception of Photic vs. Thermal Entrainment
Authors: Boikoglou Eleni , Ma Zisong , von Korff Maria , Davis Amanda M , Nagy Ferenc , Davis Seth J
Published: August 2011

The constraint of a rotating earth has led to the evolution of a circadian clock that drives anticipation of future environmental changes. During this daily rotation, the circadian clock of Arabidopsis thaliana (Arabidopsis) intersects with the diurnal environment to orchestrate virtually all transcriptional processes of the plant cell, presumably by detecting, interpreting, and anticipating the environmental alternations of light and temperature. To comparatively assess differential inputs toward phenotypic and physiological responses on a circadian parameter, we surveyed clock periodicity in a recombinant inbred population modified to allow for robust periodicity measurements after entrainment to respective photic vs. thermal cues, termed zeitgebers. Lines previously thermally entrained generally displayed reduced period length compared to those previously photically entrained. This differential zeitgeber response was also detected in a set of diverse Arabidopsis accessions. Thus, the zeitgebers of the preceding environment direct future behavior of the circadian oscillator. Allelic variation at quantitative trait loci generated significant differences in zeitgeber responses in the segregating population. These were important for periodicity variation dependent on the nature of the subsequent entrainment source. Collectively, our results provide a genetic paradigm for the basis of environmental memory of a preceding environment, which leads to the integrated coordination of circadian periodicity.
Study Designs for Identification of Rare Disease Variants in Complex Diseases: The Utility of Family-Based Designs
Authors: Ionita-Laza Iuliana , Ottman Ruth
Published: August 2011

The recent progress in sequencing technologies makes possible large-scale medical sequencing efforts to assess the importance of rare variants in complex diseases. The results of such efforts depend heavily on the use of efficient study designs and analytical methods. We introduce here a unified framework for association testing of rare variants in family-based designs or designs based on unselected affected individuals. This framework allows us to quantify the enrichment in rare disease variants in families containing multiple affected individuals and to investigate the optimal design of studies aiming to identify rare disease variants in complex traits. We show that for many complex diseases with small values for the overall sibling recurrence risk ratio, such as Alzheimer’s disease and most cancers, sequencing affected individuals with a positive family history of the disease can be extremely advantageous for identifying rare disease variants. In contrast, for complex diseases with large values of the sibling recurrence risk ratio, sequencing unselected affected individuals may be preferable.
Translation Initiation: A Regulatory Role for Poly(A) Tracts in Front of the AUG Codon in Saccharomyces cerevisiae
Authors: Xia Xuhua , MacKay Vivian , Yao Xiaoquan , Wu Jianhua , Miura Fumihito , Ito Takashi , Morris David R
Published: August 2011

The 5′-UTR serves as the loading dock for ribosomes during translation initiation and is the key site for translation regulation. Many genes in the yeast Saccharomyces cerevisiae contain poly(A) tracts in their 5′-UTRs. We studied these pre-AUG poly(A) tracts in a set of 3274 recently identified 5′-UTRs in the yeast to characterize their effect on in vivo protein abundance, ribosomal density, and protein synthesis rate in the yeast. The protein abundance and the protein synthesis rate increase with the length of the poly(A), but exhibit a dramatic decrease when the poly(A) length is ≥12. The ribosomal density also reaches the lowest level when the poly(A) length is ≥12. This supports the hypothesis that a pre-AUG poly(A) tract can bind to translation initiation factors to enhance translation initiation, but a long (≥12) pre-AUG poly(A) tract will bind to Pab1p, whose binding size is 12 consecutive A residues in yeast, resulting in repression of translation. The hypothesis explains why a long pre-AUG poly(A) leads to more efficient translation initiation than a short one when PABP is absent, and why pre-AUG poly(A) is short in the early genes but long in the late genes of vaccinia virus.
Estimating Contemporary Effective Population Size on the Basis of Linkage Disequilibrium in the Face of Migration
Authors: Waples Robin S , England Phillip R
Published: August 2011

Effective population size (Ne) is an important genetic parameter because of its relationship to loss of genetic variation, increases in inbreeding, accumulation of mutations, and effectiveness of selection. Like most other genetic approaches that estimate contemporary Ne, the method based on linkage disequilibrium (LD) assumes a closed population and (in the most common applications) randomly recombining loci. We used analytical and numerical methods to evaluate the absolute and relative consequences of two potential violations of the closed-population assumption: (1) mixture LD caused by occurrence of more than one gene pool, which would downwardly bias N^e, and (2) reductions in drift LD (and hence upward bias in N^e) caused by an increase in the number of parents responsible for local samples. The LD method is surprisingly robust to equilibrium migration. Effects of mixture LD are small for all values of migration rate (m), and effects of additional parents are also small unless m is high in genetic terms. LD estimates of Ne therefore accurately reflect local (subpopulation) Ne unless m > ∼5–10%. With higher m, N^e converges on the global (metapopulation) Ne. Two general exceptions were observed. First, equilibrium migration that is rare and hence episodic can occasionally lead to substantial mixture LD, especially when sample size is small. Second, nonequilibrium, pulse migration of strongly divergent individuals can also create strong mixture LD and depress estimates of local Ne. In both cases, assignment tests, Bayesian clustering, and other methods often will allow identification of recent immigrants that strongly influence results. In simulations involving equilibrium migration, the standard LD method performed better than a method designed to jointly estimate Ne and m. The above results assume loci are not physically linked; for tightly linked loci, the LD signal from past migration events can persist for many generations, with consequences for Ne estimates that remain to be evaluated.
Organization of the Synaptonemal Complex During Meiosis in Caenorhabditis elegans
Authors: Schild-Prüfert Kristina , Saito Takamune T , Smolikov Sarit , Gu Yanjie , Hincapie Marina , Hill David E , Vidal Marc , McDonald Kent , Colaiácovo Monica P
Published: August 2011

Four different SYP proteins (SYP-1, SYP-2, SYP-3, and SYP-4) have been proposed to form the central region of the synaptonemal complex (SC) thereby bridging the axes of paired meiotic chromosomes in Caenorhabditis elegans. Their interdependent localization suggests that they may interact within the SC. Our studies reveal for the first time how these SYP proteins are organized in the central region of the SC. Yeast two-hybrid and co-immunoprecipitation studies show that SYP-1 is the only SYP protein that is capable of homotypic interactions, and is able to interact with both SYP-2 and SYP-3 directly, whereas SYP-2 and SYP-3 do not seem to interact with each other. Specifically, the coiled-coil domain of SYP-1 is required both for its homotypic interactions and its interaction with the C-terminal domain of SYP-2. Meanwhile, SYP-3 interacts with the C-terminal end of SYP-1 via its N-terminal domain. Immunoelectron microscopy analysis provides insight into the orientation of these proteins within the SC. While the C-terminal domain of SYP-3 localizes in close proximity to the chromosome axes, the N-terminal domains of both SYP-1 and SYP-4, as well as the C-terminal domain of SYP-2, are located in the middle of the SC. Taking into account the different sizes of these proteins, their interaction abilities, and their orientation within the SC, we propose a model of how the SYP proteins link the homologous axes to provide the conserved structure and width of the SC in C. elegans.
A Boundary Element BetweenTsixandXistBinds the Chromatin Insulator Ctcf and Contributes to Initiation of X-Chromosome Inactivation
Authors: Spencer Rebecca J , del Rosario Brian C , Pinter Stefan F , Lessing Derek , Sadreyev Ruslan I , Lee Jeannie T
Published: August 2011

In mammals, X-chromosome inactivation (XCI) equalizes X-linked gene expression between XY males and XX females and is controlled by a specialized region known as the X-inactivation center (Xic). The Xic harbors two chromatin interaction domains, one centered around the noncoding Xist gene and the other around the antisense Tsix counterpart. Previous work demonstrated the existence of a chromatin transitional zone between the two domains. Here, we investigate the region and discover a conserved element, RS14, that presents a strong binding site for Ctcf protein. RS14 possesses an insulatory function suggestive of a boundary element and is crucial for cell differentiation and growth. Knocking out RS14 results in compromised Xist induction and aberrant XCI in female cells. These data demonstrate that a junction element between Tsix and Xist contributes to the initiation of XCI.
The TEA Transcription Factor Tec1 Links TOR and MAPK Pathways to Coordinate Yeast Development
Authors: Brückner Stefan , Kern Sandra , Birke Raphael , Saugar Irene , Ulrich Helle D , Mösch Hans-Ulrich
Published: August 2011

In Saccharomyces cerevisiae, the TEA transcription factor Tec1 controls several developmental programs in response to nutrients and pheromones. Tec1 is targeted by the pheromone-responsive Fus3/Kss1 mitogen-activated protein kinase (MAPK) cascade, which destabilizes the transcription factor to ensure efficient mating of sexual partner cells. The regulation of Tec1 by signaling pathways that control cell division and development in response to nutrients, however, is not known. Here, we show that Tec1 protein stability is under control of the nutrient-sensitive target of rapamycin complex 1 (TORC1) signaling pathway via the Tip41-Tap42-Sit4 branch. We further show that degradation of Tec1 upon inhibition of TORC1 by rapamycin does not involve polyubiquitylation and appears to be proteasome independent. However, rapamycin-induced Tec1 degradation depends on the HECT ubiquitin ligase Rsp5, which physically interacts with Tec1 via conserved PxY motives. We further demonstrate that rapamycin and mating pheromone control Tec1 protein stability through distinct mechanisms by targeting different domains of the transcription factor. Finally, we show that Tec1 is a positive regulator of yeast chronological lifespan (CLS), a known TORC1-regulated process. Our findings indicate that in yeast, Tec1 links TORC1 and MAPK signaling pathways to coordinate control of cellular development in response to different stimuli.
Új típusú, retrograd dissectio pancreatoduodenectomia során – korai tapasztalataink
Authors: Kelemen Dezső , Papp Róbert , Horváth Örs Péter
Published: August 2011

Absztrakt

Szerzők felhívják rá a figyelmet, hogy a pancreascarcinoma miatt végzett műtétek késői eredményei javíthatók az R0 resectiók arányának növelésével. Ennek eléréséhez adhat segítséget egy a pancreasfej eltávolítása során alkalmazható új módszer, amikor a processus uncinatusnál kezdve, caudocranialis irányba (retrograd) történik a dissectio. Ezáltal már az elején látótérbe kerül az arteria mesenterica superior, ami mentén haladva tökéletesebben lehet eltávolítani a peripancreaticus szöveteket, emellett kisebb a vérzés és a nagyérsérülés veszélye is. Szerzők 6 esetük kapcsán is megtapasztalták az említett technikai előnyöket, és valamennyi resectio R0-nak bizonyult a szövettani feldolgozáskor. Irodalmi és saját eredmények alapján ajánlják kipróbálásra a hagyományostól eltérő, retrograd dissectiót carcinoma miatt végzett pancreatoduodenectomia során.
A vékonybél meleg és hideg ischaemiás károsodásának kimutatása differenciál pásztázó kalorimetriás vizsgálattal
Authors: Nedvig Klára , Zapf István , Fekecs Tamás
Published: August 2011

Absztrakt

Bevezetés/célkitűzés: Annak ténye, hogy a vékonybél rendkívül érzékeny az ischaemiás/reperfusiós károsodásokra, indította el azokat az összehasonlító vizsgálatokat, ahol meleg és hideg ischaemia hatására a bél szöveti struktúrájában bekövetkező változásokat tanulmányoztuk differenciál pásztázó kalorimetriás (DSC) módszerrel. Anyag és módszerek: Meleg és hideg ischaemiás csoportokat hoztunk létre 1, 3 és 6 órás ischaemiás időkkel Wistar-patkányokon (n = 30). A bélszövetből mintát vettünk a laparotomia után (kontroll) és az ischaemiás periódusok végén. A DSC méréseket a bél mucosa- és izomrétegén, valamint a teljes bélfal mintáiban végeztük el. Eredmények: A DSC adatok megerősítették, hogy a meleg ischaemia idejének növelése fokozza a mucosa- és izomréteg károsodását. Az átalakulási hőmérséklet és a kalorimetriás entalpia eredmények alapján úgy tűnik, hogy a károsodás kisebb mértékű University of Wisconsin oldatban történő hideg tárolás esetén, de a bélszövet valamennyi rétegében bekövetkező termikus destructio jelzi, hogy jelentős károsodás áll fenn. Következtetések: Jelen munkánkban DSC technikával kvantitatív módon tudtuk kimutatni az ischaemia hatására a bélszövetben bekövetkező strukturális károsodásokat. Ez a termoanalitikai módszer alkalmasnak tűnik a jövőben további különböző stresszmodellek vizsgálatára.
Role of MRI in the diagnosis of neuromuscular disorders
Authors: Pál Endre , Dérczy Katalin
Published: August 2011

Recently, the assessment of the muscles using limb MRI and whole body MRI has become widely available and more frequent. In cases of muscular dystrophies it may help to select the optimal muscles for biopsy, because the severely atrophic and degenerated muscles are not suitable for histological tests. It is also known that the pattern of muscle involvement is characteristic for a certain neuromuscular disease, and clinically silent muscle damage can be visualized, as well. Therefore, imaging of muscles is helpful in neuromuscular differential diagnosis and planning genetic tests. Orv. Hetil., 2011, 152, 1362–1367.
Electroanatomical mapping and radiofrequency ablation of tachycardia originating in pulmonary vein in an adult patient
Authors: Végh Eszter Mária , Széplaki Gábor , Szilágyi Szabolcs , Osztheimer István , Tahin Tamás , Merkely Béla , Gellér László
Published: August 2011

A 29-year-old male was admitted to our outpatient clinic because of palpitation and documented narrow QRS arrhythmia. Based on the ECG, supraventricular tachycardia was diagnosed, electrophysiological examination was indicated and ablation therapy was recommended. During positioning of the catheter the patient developed arrhythmia. On the coronary sinus catheter the activation spread from distal to proximal electrodes, suggesting left atrial origin. During atrial entrainment pacing long return cycle was observed and distal coronary sinus pacing resulted in a 15 ms longer cycle length than the arrhythmia. Therefore, the left atrial origin of the arrhythmia was confirmed and double transseptal puncture was performed. Lasso and irrigated tip catheter were introduced into the left atrium and electroanatomical mapping was performed with CARTO3 system. After electroanatomical mapping the origin of tachycardia was located proximally in the left superior pulmonary vein. Ablation was started at the earliest activation point, where acceleration was observed and the arrhythmia stopped after the first ablation. Pulmonary vein isolation was completed, and bidirectional block could be confirmed. After 30 minutes the arrhythmia was not inducible. During follow-up, Holter-examination was negative and the patient remained asymptomatic. The pulmonary vein tachycardia is a supraventricular arrhythmia that can occur at any age, but the diagnosis based on the ECG is not always simple. Detailed electroanatomical mapping is very important in the diagnosis of this type of arrhythmia, although it can be verified with conventional electrophysiological methods as well. Focal ablation may be a therapeutic option; however, total isolation of pulmonary veins can be more effective. Orv. Hetil., 2011, 152, 1374–1378.