MRI Guided Interventions needs new materials and contrast agents

Abstract Magnetic resonance imaging (MRI) is primary a diagnostic tool, with or without the use of contrast agents. To enable the use of MRI for interventional purposes, devices are needed that are nonmagnetic and non-conductive and visible in MRI. Fiber-composite materials provide enough strength to replace classic metal-based devices, and at the same time provide opportunity to include contrast agents as part of the matrix. Gadolinium chelates are clinically being used ad contrast agents by delivery into the vascular space, and then diffusing into the site (tumor, scar, vessel) of interest, Apart from incomplete diffusion, they are rapidly washed out of the site, and some gadolinium chelates cause specific renal toxicity Porphyrins are potential MR contrast agents, considering their stable form within chelate complexes that comprises paramagnetic metal ions and their retention by the site selectively The present study aims to evaluate the site enhancing imaging characteristics of novel metalloporphyrin derivatives. In this project we investigate the MRI characteristics of metalloporphyrin derivatives as potential biocompatible MR contrast agent. However, to enable this several technical issues have to be resolved. Hemin is sparingly soluble in aqueous media. Therefore, derivatives of Hemin have been processed for enhancing the solubility as PEGylated Hemin, Hemin Arginate or Hemin Lysinate. This new contrast agent has achieved a high molar Relaxivity in MRI allowing decrease of the required dose for in vivo applications. These derivatives suggest that the size, geometry, and polarity of hemin can be modified to optimize their relaxivities ,pharmacokinetic properties, and biocompatibility

Electromagnetic self-forces and generalized Killing fields

Building upon previous results in scalar field theory, a formalism is developed that uses generalized Killing fields to understand the behavior of extended charges interacting with their own electromagnetic fields. New notions of effective linear and angular momenta are identified, and their evolution equations are derived exactly in arbitrary (but fixed) curved spacetimes. A slightly modified form of the Detweiler-Whiting axiom that a charge's motion should only be influenced by the so-called "regular" component of its self-field is shown to follow very easily. It is exact in some interesting cases, and approximate in most others. Explicit equations describing the center-of-mass motion, spin angular momentum, and changes in mass of a small charge are also derived in a particular limit. The chosen approximations -- although standard -- incorporate dipole and spin forces that do not appear in the traditional Abraham-Lorentz-Dirac or Dewitt-Brehme equations. They have, however, been previously identified in the test body limit.Comment: 20 pages, minor typos correcte

HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES1 Is Required for Circadian Periodicity through the Promotion of Nucleo-Cytoplasmic mRNA Export in Arabidopsis.

notes: PMCID: PMC3875725This is an open access article that is freely available in ORE or from the publisher's web site. Please cite the published version. © 2013 American Society of Plant Biologists. All rights reserved.Cold acclimation has been shown to be attenuated by the degradation of the INDUCER OF CBF EXPRESSION1 protein by the E3 ubiquitin ligase HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES1 (HOS1). However, recent work has suggested that HOS1 may have a wider range of roles in plants than previously appreciated. Here, we show that hos1 mutants are affected in circadian clock function, exhibiting a long-period phenotype in a wide range of temperature and light environments. We demonstrate that hos1 mutants accumulate polyadenylated mRNA in the nucleus and that the circadian defect in hos1 is shared by multiple mutants with aberrant mRNA export, but not in a mutant attenuated in nucleo-cytoplasmic transport of microRNAs. As revealed by RNA sequencing, hos1 exhibits gross changes to the transcriptome with genes in multiple functional categories being affected. In addition, we show that hos1 and other previously described mutants with altered mRNA export affect cold signaling in a similar manner. Our data support a model in which altered mRNA export is important for the manifestation of hos1 circadian clock defects and suggest that HOS1 may indirectly affect cold signaling through disruption of the circadian clock.Biotechnology and Biological Science Research Counci

SOCIAL CONSTRAINTS ON ADULT LANGUAGE LEARNING

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73181/1/j.1749-6632.1981.tb42015.x.pd

Defining Meyer's loop-temporal lobe resections, visual field deficits and diffusion tensor tractography

Anterior temporal lobe resection is often complicated by superior quadrantic visual field deficits (VFDs). In some cases this can be severe enough to prohibit driving, even if a patient is free of seizures. These deficits are caused by damage to Meyer's loop of the optic radiation, which shows considerable heterogeneity in its anterior extent. This structure cannot be distinguished using clinical magnetic resonance imaging sequences. Diffusion tensor tractography is an advanced magnetic resonance imaging technique that enables the parcellation of white matter. Using seed voxels antero-lateral to the lateral geniculate nucleus, we applied this technique to 20 control subjects, and 21 postoperative patients. All patients had visual fields assessed with Goldmann perimetry at least three months after surgery. We measured the distance from the tip of Meyer's loop to the temporal pole and horn in all subjects. In addition, we measured the size of temporal lobe resection using postoperative T1-weighted images, and quantified VFDs. Nine patients suffered VFDs ranging from 22% to 87% of the contralateral superior quadrant. In patients, the range of distance from the tip of Meyer's loop to the temporal pole was 24–43 mm (mean 34 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –15 to +9 mm (mean 0 mm). In controls the range of distance from the tip of Meyer's loop to the temporal pole was 24–47 mm (mean 35 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –11 to +9 mm (mean 0 mm). Both quantitative and qualitative results were in accord with recent dissections of cadaveric brains, and analysis of postoperative VFDs and resection volumes. By applying a linear regression analysis we showed that both distance from the tip of Meyer's loop to the temporal pole and the size of resection were significant predictors of the postoperative VFDs. We conclude that there is considerable variation in the anterior extent of Meyer's loop. In view of this, diffusion tensor tractography of the optic radiation is a potentially useful method to assess an individual patient's risk of postoperative VFDs following anterior temporal lobe resection

A Neuropsychoanalytical approach to the hard problem of consciousness

A neuropsychoanalytical approach to the ‘hard problem’ of consciousness revolves around the distinction between the subject and objects of consciousness. In contrast to the mainstream of cognitive science, neuropsychoanalysis prioritises the subject. The subject of consciousness is the indispensable page upon which its objects are inscribed. This has implications for our conception of the mental. The subjective being of consciousness is not registered in the classical exteroceptive modalities; it is not a cognitive representation, not a memory trace. Cognitive representations are ‘mental solids,’ embedded within subjective consciousness, and their tangible and visible (etc.) properties are projected onto reality. It is important to recognise that mental solids (e.g. the body-as-object) are no more real than the subjective being they are represented in (the body-as-subject). Moreover, pure subjectivity is not without content or quality. This aspect of consciousness is conventionally described quantitatively as the level of consciousness, ‘wakefulness’. But it feels like something to be awake. The primary modality of this aspect of consciousness is affect. Some implications of this frame of reference are discussed here, in broad brush strokes. This is an electronic version of an article published as Journal of Integrative Neuroscience, Volume 13, Issue 2, 2014, pp. 173-185. DOI: http://dx.doi.org/10.1142/S0219635214400032, © World Scientific Publishing Company, http://www.worldscientific.com/worldscinet/jin

Plasma Electronics

Contains research objectives and reports on twelve research projects.National Science Foundation under Grant G-9330U. S. Navy (Office of Naval Research) under Contract Nonr-1841(78)U. S. NavyLincoln Laboratory, Purchase Order DDL B-00306U. S. ArmyU. S. Air Force under Air Force Contract AF19(604)-740

Trait analysis reveals DOG1 determines initial depth of seed dormancy, but not changes during dormancy cycling that result in seedling emergence timing.

Seedling emergence timing is crucial in competitive plant communities and so contributes to species fitness. To understand the mechanistic basis of variation in seedling emergence timing, we exploited the contrasting behaviour of two Arabidopsis ecotypes; Cape Verde island (Cvi) and Burren (Bur-0). We used RNAseq analysis of RNA from exhumed seeds and quantitative trait loci (QTL) analyses on a mapping population from crossing the Cvi and Bur-0 ecotypes. We determined genome-wide expression patterns over an annual dormancy cycle in both ecotypes identifying nine major clusters based on the seasonal timing of gene expression, and variation in behaviour between them. QTL were identified for depth of seed dormancy and Seedling Emergence Timing (SET). Both analyses showed a key role for DOG1 in determining depth of dormancy, but did not support a direct role for DOG1 in generating altered seasonal patterns of seedling emergence. The principle QTL determining Seedling Emergence Timing (SET1: dormancy cycling) is physically close on chromosome 5, but distinct from DOG1. We show that SET1 and two other SET QTLs each contain a candidate gene (AHG1, ANAC60, PDF1 respectively) closely associated to DOG1 and abscisic acid signalling and suggest a model for the control of SET in the field

Momentum of an electromagnetic wave in dielectric media

Almost a hundred years ago, two different expressions were proposed for the energy--momentum tensor of an electromagnetic wave in a dielectric. Minkowski's tensor predicted an increase in the linear momentum of the wave on entering a dielectric medium, whereas Abraham's tensor predicted its decrease. Theoretical arguments were advanced in favour of both sides, and experiments proved incapable of distinguishing between the two. Yet more forms were proposed, each with their advocates who considered the form that they were proposing to be the one true tensor. This paper reviews the debate and its eventual conclusion: that no electromagnetic wave energy--momentum tensor is complete on its own. When the appropriate accompanying energy--momentum tensor for the material medium is also considered, experimental predictions of all the various proposed tensors will always be the same, and the preferred form is therefore effectively a matter of personal choice.Comment: 23 pages, 3 figures, RevTeX 4. Removed erroneous factor of mu/mu_0 from Eq.(44

Transcranial magnetic stimulation in sport science: a commentary

The aim of this commentary is to provide a brief overview of transcranial magnetic stimulation (TMS) and highlight how this technique can be used to investigate the acute and chronic responses of the central nervous system to exercise. We characterise the neuromuscular responses to TMS and discuss how these measures can be used to investigate the mechanisms of fatigue in response to locomotor exercise. We also discuss how TMS might be used to study the corticospinal adaptations to resistance exercise training, with particular emphasis on the responses to shortening/lengthening contractions and contralateral training. The limited data to date suggest that TMS is a valuable technique for exploring the mechanisms of central fatigue and neural adaptation