Sequelae in children following cerebellar tumor removal surgery are well defined, and predictors for poor recovery include lesions of the cerebellar nuclei and the inferior vermis. Dynamic reorganization is thought to promote functional recovery in particular within the first year after surgery. Yet, the time course and mechanisms of recovery within this critical time frame are elusive and longitudinal studies are missing. Thus, a group of children and adolescents (n = 12, range 6-17 years) were followed longitudinally after cerebellar surgery and compared to age- and gender-matched controls (n = 11). Patients were examined (1) within the first days, (2) 3 months, and (3) 1 year after surgery. Each time behavioral tests of balance and upper limb motor function, ataxia rating, and a MRI scan were performed. Data were used for subsequent lesion-symptom mapping of cerebellar function. Behavioral improvements continued beyond 3 months, but were not complete in all patients after 1 year. At that time, remaining deficits were mild. Within the first 3 months, cerebellar lesion volumes were notably reduced by vanishing edema. Reduction in edema affecting the deep cerebellar nuclei but not reduction of total cerebellar lesion volume was a major predictor of early functional recovery. Persistent impairment in balance and upper limb function was linked to permanent lesions of the inferior vermis and the deep cerebellar nuclei.
Sequence analysis of three representative gene loci, oriC, ampC and fliC, in 19 Pseudomonas aeruginosa strains revealed a low sequence diversity that does not correlate with the extensive diversity of P. aeruginosa habitats. Single point mutations lead to a mean sequence diversity of 0.40%, 0.38% and 0.59% for oriC, ampC and a-type fliC, respectively, but of only 0.05% for b-type flagellin genes. The analyzed genes encode highly conserved functions that are subject to strong selective pressure. The detected nucleotide substitutions of oriC, accumulating in a central 95 bp region, affect neither the putative DnaA binding sites nor the 13 bp direct repeats that presumably provide the sites to open oriC duplex DNA. Even in P. aeruginosa strain DSM 1128, which exhibits an unusually high sequence variability in several analyzed genes, the 9 bp and 13 bp motifs are conserved, reflecting their essential functional role in replication initiation. The two flagellin types, differing by 37-38% in their primary structure, exhibit pronounced structural and functional homology, as shown by alignment of flagellin variants by hydrophobicity index, probability of surface exposure, chain flexibility and antigenicity, and by cross-reactivity between both proteins using specific antisera. Five nonsynonymous nucleotide substitutions of ampC lead to beta-lactamase variants that differ in recognition and turnover of substrate, as deduced from the three-dimensional structure of the highly homologous Enterobacter cloacae beta-lactamase and confirmed by inhibition kinetics. The identified point mutations in the three genes are classified as selectively equivalent sequence variants indicating neutral genetic drift as a mechanism of molecular evolution in P. aeruginosa, rather than positive selection.
All known pilin sequences in Pseudomonas aeruginosa were amplified by a set of consensus primers located in the 5"-conserved region of pilA and the threonine-specific t-RNA following pilA. This also enabled the discovery of a novel pilin gene in a strain pair of clonal variants, which differs from known pilin genes in its increased GC-content. The mature protein has 173 amino acids making it the longest pilin known to date in P. aeruginosa. Different inserted sequences detected between the 3"-end of the pilin gene and the t-RNA in this strain and in strains with group I pilin genes seemed to be specific for each pilin group indicating a horizontal cotransfer of sequences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.