An Expanded Set of Amino Acid Analogs for the Ribosomal Translation of Unnatural Peptides

BACKGROUND: The application of in vitro translation to the synthesis of unnatural peptides may allow the production of extremely large libraries of highly modified peptides, which are a potential source of lead compounds in the search for new pharmaceutical agents. The specificity of the translation apparatus, however, limits the diversity of unnatural amino acids that can be incorporated into peptides by ribosomal translation. We have previously shown that over 90 unnatural amino acids can be enzymatically loaded onto tRNA. METHODOLOGY/PRINCIPAL FINDINGS: We have now used a competition assay to assess the efficiency of tRNA-aminoacylation of these analogs. We have also used a series of peptide translation assays to measure the efficiency with which these analogs are incorporated into peptides. The translation apparatus tolerates most side chain derivatives, a few alpha,alpha disubstituted, N-methyl and alpha-hydroxy derivatives, but no beta-amino acids. We show that over 50 unnatural amino acids can be incorporated into peptides by ribosomal translation. Using a set of analogs that are efficiently charged and translated we were able to prepare individual peptides containing up to 13 different unnatural amino acids. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that a diverse array of unnatural building blocks can be translationally incorporated into peptides. These building blocks provide new opportunities for in vitro selections with highly modified drug-like peptides

Robotic Gait Training in an Adult With Cerebral Palsy: A Case Report.

Improved treatments and rehabilitation for cerebral palsy (CP) have led to an increased number of children with CP surviving into adulthood. Adults with CP show an increased prevalence of pain, fatigue, and musculoskeletal dysfunction, leading to a decrease in ambulatory function. Recent work has demonstrated the potential benefits of intensive task-specific gait training, including the use of robotic-driven gait orthoses, on motor recovery in children with CP [1 and 2]. In contrast, reports of interventions aimed at improving motor function in adults with CP are lacking. This case study reports on the outcomes of a 6-week intervention of robotic-assisted gait training administered to a 52-year-old woman with right hemiplegia attributable to CP. Improvements were noted in balance, walking speed, and time to negotiate stairs at posttraining and follow-up. Gait analysis showed an increase in step length and a reduction in the period of double support. In conclusion, robotic-assisted gait training may be beneficial in enhancing locomotor function in adults with CP

A personal perspective on the evolution of empirical software engineering

This paper offers a four-decade overview of the evolution of empirical software engineering from a personal perspective. It represents what I saw as major milestones in terms of the kind of thinking that affected the nature of the work. I use examples from my own work as I feel that work followed the evolution of the field and is representative of the thinking at various points in time. I try to say where we fell short and where we need to go, in the end discussing the barriers we still need to address

Larval density mediates knockdown resistance to pyrethroid insecticides in adult Aedes aegypti

Abstract Background Understanding mechanisms driving insecticide resistance in vector populations remains a public health priority. To date, most research has focused on the genetic mechanisms underpinning resistance, yet it is unclear what role environmental drivers may play in shaping phenotypic expression. One of the key environmental drivers of Aedes aegypti mosquito population dynamics is resource-driven intraspecific competition at the larval stage. We experimentally investigated the role of density-dependent larval competition in mediating resistance evolution in Ae. aegypti, using knockdown resistance (kdr) as a marker of genotypic resistance and CDC bottle bioassays to determine phenotype. We reared first-instar larvae from susceptible and pyrethroid-resistant field-derived populations of Ae. aegypti at high and low density and measured the resulting phenotypic resistance and population kdr allele frequencies. Results At low density, only 48.2% of the resistant population was knocked down, yet at high density, the population was no longer phenotypically resistant - 93% were knocked down when exposed to permethrin, which is considered susceptible according to WHO guidelines. Furthermore, the frequency of the C1534 kdr allele in the resistant population at high density decreased from 0.98 ± 0.04 to 0.69 ± 0.04 in only one generation of selection. Conclusions Our results indicate that larval conditions, specifically density, can impact both phenotype and genotype of pyrethroid-resistant populations. Furthermore, phenotypic susceptibility to pyrethroids may be re-established in a resistant population through a gene x environment interaction, a finding that can lead to the development of novel resistance management strategies that capitalize on density-induced costs