Surface functionalization of magnetic iron oxide nanoparticles for MRI applications – effect of anchoring group and ligand exchange protocol

Hydrophobic magnetite nanoparticles synthesized from thermal decomposition of iron salts must be rendered hydrophilic for their application as MRI contrast agents. This process requires refunctionalizing the surface of the nanoparticles with a hydrophilic organic coating such as polyethylene glycol. Two parameters were found to influence the magnetic behavior and relaxivity of the resulting hydrophilic iron oxide nanoparticles: the functionality of the anchoring group and the protocol followed for the functionalization. Nanoparticles coated with PEGs via a catecholate‐type anchoring moiety maintain the saturation magnetization and relaxivity of the hydrophobic magnetite precursor. Other anchoring functionalities, such as phosphonate, carboxylate and dopamine decrease the magnetization and relaxivity of the contrast agent. The protocol for functionalizing the nanoparticles also influences the magnetic behavior of the material. Nanoparticles refunctionalized according to a direct biphasic protocol exhibit higher relaxivity than those refunctionalized according to a two‐step procedure which first involves stripping the nanoparticles. This research presents the first systematic study of both the binding moiety and the functionalization protocol on the relaxivity and magnetization of water‐soluble coated iron oxide nanoparticles used as MRI contrast agents. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of bicuculline and strychnine on synaptic inputs to edge cells during fictive locomotion

Edge cells are mechanoreceptive neurones located in the lateral tracts of the lamprey spinal cord. Phasic activation of these cells by lateral bending can entrain the activity of the locomotor central pattern generator. During fictive locomotion induced by bath-applied NMDLA (N-methyl-D,L-aspartate) or sensory stimulation, edge cells receive synaptic input. In this paper we provide evidence that the tonic inhibition received during sensory-induced fictive locomotion is glycinergic. We also show that during fictive locomotion induced by application of NMDLA to the spinal cord, bicuculline unveils phasic synaptic activity in edge cells. During sensory-evoked fictive locomotion, by contrast, only tonic synaptic activity is apparent in the presence of bicuculline.     

Said Another Way. Is the ADN Graduate Prepared to Practice in Community Settings?

The downsizing and closing of acute care facilities and the movement to community-based healthcare services are decreasing the need for RNs in acute care facilities. In the past, the associate-degree nurse (ADN) has filled the majority of positions in acute care. With the trend to provide health services in community setting, will the ADN be prepared for positions in community facilities? ADN educators must reevaluate how they are educating students for practice. The author reviews the 1995 recommendations from the Pew Health Professions Commission and relevant current directives from the National League for Nursing.     

Top1- and Top2-mediated topological transitions at replication forks ensure fork progression and stability and prevent DNA damage checkpoint activation

DNA topoisomerases solve topological problems during chromosome metabolism. We investigated where and when Top1 and Top2 are recruited on replicating chromosomes and how their inactivation affects fork integrity and DNA damage checkpoint activation. We show that, in the context of replicating chromatin, Top1 and Top2 act within a 600-base-pair (bp) region spanning the moving forks. Top2 exhibits additional S-phase clusters at specific intergenic loci, mostly containing promoters. TOP1 ablation does not affect fork progression and stability and does not cause activation of the Rad53 checkpoint kinase. top2 mutants accumulate sister chromatid junctions in S phase without affecting fork progression and activate Rad53 at the M-G1 transition. top1 top2 double mutants exhibit fork block and processing and phosphorylation of Rad53 and gamma H2A in S phase. The exonuclease Exo1 influences fork processing and DNA damage checkpoint activation in top1 top2 mutants. Our data are consistent with a coordinated action of Top1 and Top2 in counteracting the accumulation of torsional stress and sister chromatid entanglement at replication forks, thus preventing the diffusion of topological changes along large chromosomal regions. A failure in resolving fork-related topological constrains during S phase may therefore result in abnormal chromosome transitions, DNA damage checkpoint activation, and chromosome breakage during segregation.     

Evaluation of the growth percentiles of children with congenital heart disease

The purpose of this study was to evaluate the correlation between anthropometric measures of children with congenital heart disease with percentiles that represent their growth indicators. Anthropometric evaluations of 135 hospitalized children with congenital heart disease were performed in a hospital specialized in cardiac diseases in Fortaleza, CE, Brazil. For the growth evaluation, percentiles of height by age, weight by height and weight by age were calculated. Children's average age was 4.74 months (+ 3.78) and 66.7% of the children were male. The medians of the three percentiles presented values below percentile 10, indicating a high proportion of values considered of risk. The subscapular thickness presented positive correlation with the three percentiles. The values of percentiles studied indicated growth delay.