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Search Results: 1 - 10 of 403710 matches for " Christina M. Freisinger "
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Regulator of G Protein Signaling 3 Modulates Wnt5b Calcium Dynamics and Somite Patterning
Christina M. Freisinger,Rory A. Fisher,Diane C. Slusarski
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1001020
Abstract: Vertebrate development requires communication among cells of the embryo in order to define the body axis, and the Wnt-signaling network plays a key role in axis formation as well as in a vast array of other cellular processes. One arm of the Wnt-signaling network, the non-canonical Wnt pathway, mediates intracellular calcium release via activation of heterotrimeric G proteins. Regulator of G protein Signaling (RGS) proteins can accelerate inactivation of G proteins by acting as G protein GTPase-activating proteins (GAPs), however, the possible role of RGS proteins in non-canonical Wnt signaling and development is not known. Here, we identify rgs3 as having an overlapping expression pattern with wnt5b in zebrafish and reveal that individual knockdown of either rgs3 or wnt5b gene function produces similar somite patterning defects. Additionally, we describe endogenous calcium release dynamics in developing zebrafish somites and determine that both rgs3 and wnt5b function are required for appropriate frequency and amplitude of calcium release activity. Using rescue of gene knockdown and in vivo calcium imaging assays, we demonstrate that the activity of Rgs3 requires its ability to interact with Gα subunits and function as a G protein GAP. Thus, Rgs3 function is necessary for appropriate frequency and amplitude of calcium release during somitogenesis and is downstream of Wnt5 activity. These results provide the first evidence for an essential developmental role of RGS proteins in modulating the duration of non-canonical Wnt signaling.
A Novel Role for MAPKAPK2 in Morphogenesis during Zebrafish Development
Beth A. Holloway,Sol Gomez de la Torre Canny equal contributor,Ying Ye equal contributor,Diane C. Slusarski,Christina M. Freisinger,Roland Dosch,Margaret M. Chou,Daniel S. Wagner ,Mary C. Mullins
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000413
Abstract: One of the earliest morphogenetic processes in the development of many animals is epiboly. In the zebrafish, epiboly ensues when the animally localized blastoderm cells spread, thin over, and enclose the vegetally localized yolk. Only a few factors are known to function in this fundamental process. We identified a maternal-effect mutant, betty boop (bbp), which displays a novel defect in epiboly, wherein the blastoderm margin constricts dramatically, precisely when half of the yolk cell is covered by the blastoderm, causing the yolk cell to burst. Whole-blastoderm transplants and mRNA microinjection rescue demonstrate that Bbp functions in the yolk cell to regulate epiboly. We positionally cloned the maternal-effect bbp mutant gene and identified it as the zebrafish homolog of the serine-threonine kinase Mitogen Activated Protein Kinase Activated Protein Kinase 2, or MAPKAPK2, which was not previously known to function in embryonic development. We show that the regulation of MAPKAPK2 is conserved and p38 MAP kinase functions upstream of MAPKAPK2 in regulating epiboly in the zebrafish embryo. Dramatic alterations in calcium dynamics, together with the massive marginal constrictive force observed in bbp mutants, indicate precocious constriction of an F-actin network within the yolk cell, which first forms at 50% epiboly and regulates epiboly progression. We show that MAPKAPK2 activity and its regulator p38 MAPK function in the yolk cell to regulate the process of epiboly, identifying a new pathway regulating this cell movement process. We postulate that a p38 MAPKAPK2 kinase cascade modulates the activity of F-actin at the yolk cell margin circumference allowing the gradual closure of the blastopore as epiboly progresses.
Paul Ric ur and the Relationship Between Philosophy and Religion in Contemporary French Phenomenology Paul Ric ur and the Relationship Between Philosophy and Religion in Contemporary French Phenomenology
Christina M. Gschwandtner
études Ricoeuriennes / Ricoeur Studies , 2012, DOI: 10.5195/errs.2012.147
Abstract: In this paper I consider Ric ur’s negotiation of the boundary or relationship between philosophy and religion in light of the larger debate in contemporary French philosophy. I suggest that contrasting his way of dealing with the intersection of the two discourses to that of two other French thinkers (Jean-Luc Marion and Michel Henry) illuminates his stance more fully. I begin with a brief outline of Ric ur’s claims about the distinction or relation between the discourses, then reflect on those of Marion and Henry, who although they do not relate them in the same way still together form a significant contrast to Ric ur’s perspective, and conclude with a fuller consideration of Ric ur’s methodology in light of this comparison. I suggest that it is in particular his hermeneutic commitments that lead him both to more rigorous distinctions between discourses and ironically to greater mediation. Det article analyse la manière dont Ricoeur pense la frontière ou la relation entre philosophie et religion à lalumière du débat plus large sur la philosophie fran aise contemporaine. Le contraste entre sa fa on detraiter l' intersection entre les deux discours et celle de deux autres penseurs fran ais (Jean--‐ Luc Marion etMichel Henry) éclaire sa position plus en profondeur. J' entame mon propos par un bref aper u des objectifsde Ricoeur s' agissant de la distinction ou de la relation entre les deux discours, puis je poursuis la réflexionen exposant les objectifs de Marion et de Henry. Bien que chacun de ces deux penseurs converge vers unevoie qui lui est propre, ils forment ensemble un contraste saisissant avec la perspective de Ricoeur. Je conclusmon article en prenant mieux en compte la méthodologie de Ricoeur à la lumière de cette comparaison.C' est en particulier ses engagements herméneutiques qui le conduisent à la fois à plus de distinctionsrigoureuses entre les discours et ironiquement à une plus grande médiation entre eux.
Dendritic inhibition mediated by O-LM and bistratified interneurons in the hippocampus
Christina Müller
Frontiers in Synaptic Neuroscience , 2014, DOI: 10.3389/fnsyn.2014.00023
Abstract: In the CA1 region of the hippocampus pyramidal neurons and GABAergic interneurons form local microcircuits. The CA1 interneurons are a diverse group consisting of many subtypes, some of which provide compartment-specific inhibition specifically onto pyramidal neuron dendrites. In fact, the majority of inhibitory synapses on pyramidal neurons is found on their dendrites. The specific role of a dendrite-innervating interneuron subtype is primarily determined by its innervation pattern on the distinct dendritic domains of pyramidal neurons. The efficacy of dendritic inhibition in reducing dendritic excitation depends on the relative timing and location of the activated excitatory and inhibitory synapses. In-vivo, synaptic properties such as short-term plasticity and neuro-modulation by the basal forebrain, govern the degree of inhibition in distinct dendritic domains in a dynamic, behavior dependent manner, specifically during network oscillation such as the theta rhythm. In this review we focus on two subtypes of dendrite-innervating interneurons: the oriens-lacunosum moleculare (O-LM) interneuron and the bistratified interneuron. Their molecular marker profile, morphology, and function in-vivo and in-vitro are well studied. We strive to integrate this diverse information from the cellular to the network level, and to provide insight into how the different characteristics of O-LM and bistratified interneurons affect dendritic excitability, network activity and behavior.
The Effects of Substructure on Galaxy Cluster Mass Determinations
Christina M. Bird
Physics , 1995, DOI: 10.1086/187895
Abstract: Although numerous studies of individual galaxy clusters have demonstrated the presence of significant substructure, previous studies of the distribution of masses of galaxy clusters determined from optical observations have failed to explicitly correct for substructure in those systems. In this {\it Letter} I present the distributions of velocity dispersion, mean separation, and dynamical masses of clusters when substructure is eliminated from the cluster datasets. I also discuss the changes in these distributions because of the substructure correction. Comparing the masses of clusters with central galaxies before and after correction for the presence of substructure reveals a significant change. This change is driven by reductions in the mean separation of galaxies, not by a decrease in the velocity dispersions as has generally been assumed. Correction for substructure reduces most significantly the masses of systems with cool X-ray temperatures, suggesting that the use of a constant linear radius (1.5$h _{100} ^{-1}$ Mpc in this study) to determine cluster membership is inappropriate for clusters spanning a range of temperatures and/or morphologies.
Substructure in Clusters and Central Galaxy Peculiar Velocities
Christina M. Bird
Physics , 1994, DOI: 10.1086/116973
Abstract: Formation theories for central dominant galaxies in clusters require them to be located at the minimum of the cluster gravitational potential. However, 32\% (8 out of 25) of the clusters with more than 50 measured redshifts have central galaxies with significant velocity offsets (with respect to other cluster members). By studying their velocity distributions and correlations between velocity and position, I show that the presence of a large peculiar velocity is strongly correlated with the presence of substructure in these massive systems. About 85\% (21 of 25) of all well-studied clusters show some evidence for substructure, in contrast to the 30-40\% found when using only galaxy or gas distributions. The correlation between substructure and central galaxy location verifies the hypothesis of Merritt (1985) and Tremaine (1990) that high peculiar velocities are indicative of recent merger events between less-massive systems of galaxies. Dynamical friction should act quickly to pull the central galaxy, the most massive discrete object in a cluster, to the minimum of the potential. The less-massive galaxies retain information about their primordial subclusters for a longer period of time. I use an objective partitioning algorithm to assign cluster galaxies to their host subclumps. When galaxies are allocated in this fashion to their subclusters, 75\% of the significant velocity offsets are eliminated. Only 2 out of the 25 clusters have central galaxies which are not centrally-located when substructure is considered in the analysis.
Solution Structure of the Circular γ-Domain Analog from the Wheat Metallothionein Ec-1
Katsiaryna Tarasava,Silke Johannsen,Eva Freisinger
Molecules , 2013, DOI: 10.3390/molecules181114414
Abstract: The first cyclic analog of a metallothionein (MT) was prepared and analyzed by UV and (magnetic) circular dichroism spectroscopy, ESI-MS as well as NMR spectroscopy. Results reveal that the evaluated cyclic g-E c-1 domain of the wheat MT E c-1 retains its ability to coordinate two Zn(II) or Cd(II) ions and adopts a three-dimensional structure that is highly similar to the one of the linear wild-type form. However, the reduced flexibility of the protein backbone facilitates structure solution significantly and results in a certain stabilization of metal binding to the protein.
Simulating a Guitar with a Conventional Sonometer  [PDF]
Zily Burstein, Christina M. Gower, Gabriele U. Varieschi
Open Journal of Acoustics (OJA) , 2012, DOI: 10.4236/oja.2012.22007
Abstract: In this paper we present a simple way to convert a conventional sonometer into a simulated fretted instrument, such as a guitar or similar, by adding a fingerboard to the sonometer. In particular, we use this modified apparatus in relation to the problem of the instrument intonation, i.e., how to obtain correctly tuned notes on these string instruments. The experimental procedures presented in this study can become a more structured laboratory activity to be used in general physics courses or acoustics classes.
Recurrent ameloblastoma of the mandible: Surgical seeding or metastasis of malignant ameloblastoma?  [PDF]
Christina Klee, Sven Lindskog, Jan-M. Hirsch, Andreas Thor
Case Reports in Clinical Medicine (CRCM) , 2013, DOI: 10.4236/crcm.2013.22042

The controversy of surgical seeding or metastasis of a recurrent ameloblastoma is discussed in this paper, where we present a case with a history of 28 years since primary diagnosis including several tumor removals and reconstructive events. 23 years after primary diagnosis, we removed a metastasis from the neck with similar histological features as the primary tumor and the following recurrences of the mandible. We argue that the removed tumor in the neck most possibly has its origin in surgical seeding of cells during earlier resection and reconstruction and not by common ways of metastasis. The seeding of tumor cells during tumor surgery and metastasis rate of malignant ameloblastoma is discussed and the literature in this area is reviewed in the paper.

Rural High School Students’ Sexual Behavior and Self-Esteem  [PDF]
Brian Unis, Inger Johansson, Christina S?llstr?m
Open Journal of Nursing (OJN) , 2015, DOI: 10.4236/ojn.2015.51004
Abstract: Background: Negative consequences for sexual health may be caused by risky sexual behavior related to attitudes, norms and self-efficacy regarding sexuality. Research has not resulted in a consensus on the associations between self-esteem and adolescents’ sexual behavior. Aims and Objectives: The aim of the study was to describe high school students’ sexual behavior and self-esteem, along with investigating the relationship of attitudes, norms, self-efficacy, and self-esteem to sexual risk behavior. Another aim was to describe and compare gender differences in self-esteem and sexual risk behavior in high school students in a rural context. Methodological Design: A cross-sectional design was used. The participants were 139 high school students, 16 to 18 years of age, sample size was decided by power calculation, and systematic randomized sampling was used. The students replied to a questionnaire about self-esteem, factors affecting sexual risk behavior, and sexual behavior. Results: Swedish high school students reported having few sexual partners, a low use of alcohol along with sex, yet a low consistency in condom use. The students reported both high basic self-esteem as well as earned self-esteem. Basic self-esteem was higher for male students while earned self-esteem was higher for female students. Significant correlations were found between self-esteem and some factors affecting sexual risk behavior related to condom use. Conclusion: High school students exhibited positive sexual behaviors and high levels of self-esteem, yet they put themselves at risk by inconsistent use of condoms. Our findings can contribute the need of to an awareness of the role self-esteem, attitudes, norms and self-efficacy plays in adolescents’ sexual behavior. Nurses working at the youth clinics are in a key position to discuss sexual health issues with adolescents to promote healthy outcomes in sexual health.
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