Sustained attention in children with two etiologies of early hydrocephalus.

Several studies have shown that children with spina bifida meningomyelocele (SBM) and hydrocephalus have attention problems on parent ratings and difficulties in stimulus orienting associated with a posterior brain attention system. Less is known about response control and inhibition associated with an anterior brain attention system. Using the Gordon Vigilance Task (Gordon, 1983), we studied error rate, reaction time, and performance over time for sustained attention, a key anterior attention function, in 101 children with SBM, 17 with aqueductal stenosis (AS; another condition involving congenital hydrocephalus), and 40 typically developing controls (NC). In SBM, we investigated the relation between cognitive attention and parent ratings of inattention and hyperactivity and explored the impact of medical variables. Children with SBM did not differ from AS or NC groups on measures of sustained attention, but they committed more errors and responded more slowly. Approximately one-third of the SBM group had attention symptoms, although parent attention ratings were not associated with task performance. Hydrocephalus does not account for the attention profile of children with SBM, which also reflects the distinctive brain dysmorphologies associated with this condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of oligosaccharides on rejection and reperfusion injury after lung transplantation

PURPOSE: We developed two models that are modifications of our original poly(2-hydroxyethyl methacrylate) (PHEMA) core-and-skirt keratoprosthesis. In these keratoprostheses, the mechanical strength of the skirt has been considerably increased with divinyl glycol (DVG) as a cross-linking agent during polymerization. In one (KPro I), methyl methacrylate (MMA) was added as comonomer to increase cell adhesion, and in the other (KPro II), HEMA was polymerized with DVG without comonomer. The aim of this study was to evaluate the process of healing and biocolonization and to ascertain whether KPro I demonstrates better ingrowth than the mechanically stronger KPro II, after implantation in rabbit eyes. METHODS: Ten rabbits were used for each model and studied at five predetermined end points up to 26 weeks. The device was implanted as a full-thickness keratoprosthesis covered with a conjunctival flap. RESULTS: Neither prosthesis demonstrated extrusion or retroprosthetic membrane formation. There was no significant difference between the two types of prosthesis with respect to tissue ingrowth and surrounding tissue melting. Histologically, inflammation was not severe, but calcification was seen in most specimens. Evidence of biodegradation of the prosthesis also was seen. CONCLUSION: In our original keratoprosthesis, fibrovascular invasion had occurred into the prosthetic skirt, but wound dehiscence and low mechanical strength resulted in an unfavorable outcome. In this series, the mechanical properties were improved, and KPro II was stronger than KPro I. Therefore KPro II would be the preferred polymer combination for surgical manipulation. However, biodegradation and calcification require further investigation into the degree and significance of these adverse reactions.     

A cruciform-dumbbell model for inverted dimer formation mediated by inverted repeats

Small inverted repeats (small palindromes) on plasmids have been shown to mediate a recombinational rearrangement event in Escherichia coli leading to the formation of inverted dimers (giant palindromes). This recombinational rearrangement event is efficient and independent of RecA and RecBCD. In this report, we propose a cruciform-dumbbell model to explain the inverted dimer formation mediated by inverted repeats. In this model, the inverted repeats promote the formation of a DNA cruciform which is processed by an endonuclease into a linear DNA with two hairpin loops at its ends. Upon DNA replication, this linear dumbbell-like DNA is then converted to the inverted dimer. In support of this model, linear dumbbell DNA molecules with unidirectional origin of DNA replication (ColE1 ori ) have been constructed and shown to transform E.coli efficiently resulting in the formation of the inverted dimer. The ability of linear dumbbell DNA to transform E.coli suggests that the terminal loops may be important in bypassing the requirement of DNA supercoiling for initiation of replication of the ColE1 ori.