Cloning of Physarum actin sequences in an exonuclease-deficient bacterial host.

A genomic library of Physarum was constructed in the replacement vector EMBL3. Efficient propagation of the recombinant phages occurred only on the recBC-sbcB- host Escherichia coli CES200, which is deficient in the exonucleases I and V. Thirteen different recombinants with actin-related sequences were detected and 10 were purified from 90,000 plaques (the equivalent of 6 Physarum genomes) on strain CES200. Comparison of the plating efficiencies of the library and the actin-related isolates suggests that palindromic DNA sequences are responsible for the instability of Physarum DNA in E. coli. In one of these isolates, lambda PpA10, and in a 2.81-kilobase subclone of that isolate in plasmid pBR322, a deletion of 360 base pairs was detected that led to stable propagation of the recombinant DNA molecules in Rec+ E. coli. Electron microscopic analysis of the 2.81-kilobase fragment, after denaturation and self-hybridization, revealed secondary structures consistent with "foldback" structures. Restriction and DNA blot analysis of lambda PpA10 suggest that the unstable DNA segment is in close proximity to, if not part of, the previously defined actin-gene locus ardA.     

The effects of stimulus timing features on P300 speller performance

ObjectiveDespite numerous examinations of factors affecting P300 speller performance, the impact of stimulus presentation parameters remains incompletely understood. This study examines the effects of four distinct stimulus presentation parameters (stimulus-off time [ISI¹], interstimulus interval [ISI], flash duration, and flash-duration:ISI ratio) on the accuracy and efficiency of the P300 speller performance.MethodsEEG data from a 32-electrode set were recorded from six subjects using a row–column paradigm of the speller task and analyzed offline.ResultsP300 speller accuracy is affected by the number of trial repetitions (F(14,354) = 69.002, p < 0.0001), as expected. In addition, longer ISI and ISI¹ times resulted in higher accuracy and characters per minute [CPM] rates. Subsets of the entire group (i.e. good vs. poor performers) were compared to show consistency of performance trends despite great variance among subjects. Moreover, the same significant effects were observed whether using the entire 32-electrode dataset or the reduced 8-channel set described by Sharbrough et al. (1991).ConclusionsDespite variability in user performance, both ISI¹ and ISI can affect P300 speller performance.SignificanceP300 system optimization must consider critical stimulus timing features including ISI¹ and ISI. Further characterization of the impact of these timing features in online experiments is warranted and the differential effect on accuracy and CPM should be more comprehensively explored.     

Pre- and post-intervention study to assess the impact of a sedation protocol in critically ill surgical patients

Introduction

Sedation and pain management for mechanically ventilated critically ill surgical patients pose many challenges for the intensivist. Even though daily interruption of sedatives and opioids is appropriate in medical intensive care unit (ICU) patients, it may not be feasible in the surgical patients with pain from surgical incision or trauma. Therefore we developed an analgesia/sedation based protocol for the surgical ICU population.

Methods

We performed a two-phase prospective observational control study. We evaluated a prescriber driven analgesia/sedation protocol (ASP) in a 12-bed surgical ICU. The pre-ASP group was sedated as usual (n = 100) and the post-ASP group was managed with the new ASP (n = 100). Each phase of the study lasted for 5 mo. Comparisons between the two groups were performed by χ² or Fisher’s exact test for categorical variables and the Mann-Whitney test for nonparametric variables. A P value <0.05 was statistically significant.

Results

We found a significant reduction in the use of fentanyl (P < 0.001) and midazolam (P = 0.001). We achieved sedation goals of 86.8% in the post-ASP group compared to 74.4% in the pre-ASP (P < 0.001). Mean mechanical ventilations days in pre- and post-ASP group were 5.9 versus 3.8 (P = 0.033).

Conclusion

In our cohort of critically ill surgery patients implementation of an ASP resulted in reduced use of continuously infused benzodiazepines and opioids, a decline in cumulative benzodiazepine and analgesic dosages, and a greater percentage of Richmond Agitation Sedation Scale scores at goal. We also showed reduced mechanical ventilation days.