Global and non-Global slow oscillations differentiate in their depth profiles

Sleep slow oscillations (SOs, 0.5-1.5 Hz) are thought to organize activity across cortical and subcortical structures, leading to selective synaptic changes that mediate consolidation of recent memories. Currently, the specific mechanism that allows for this selectively coherent activation across brain regions is not understood. Our previous research has shown that SOs can be classified on the scalp as Global, Local or Frontal, where Global SOs are found in most electrodes within a short time delay and gate long-range information flow during NREM sleep. The functional significance of space-time profiles of SOs hinges on testing if these differential SOs scalp profiles are mirrored by differential depth structure of SOs in the brain. In this study, we built an analytical framework to allow for the characterization of SO depth profiles in space-time across cortical and sub-cortical regions. To test if the two SO types could be differentiated in their cortical-subcortical activity, we trained 30 machine learning classification algorithms to distinguish Global and non-Global SOs within each individual, and repeated this analysis for light (Stage 2, S2) and deep (slow wave sleep, SWS) NREM stages separately. Multiple algorithms reached high performance across all participants, in particular algorithms based on k-nearest neighbors classification principles. Univariate feature ranking and selection showed that the most differentiating features for Global vs. non-Global SOs appeared around the trough of the SO, and in regions including cortex, thalamus, caudate nucleus, and brainstem. Results also indicated that differentiation during S2 required an extended network of current from cortical-subcortical regions, including all regions found in SWS and other basal ganglia regions, and amygdala and hippocampus, suggesting a potential functional differentiation in the role of Global SOs in S2 vs. SWS. We interpret our results as supporting the potential functional difference of Global and non-Global SOs in sleep dynamics.

Chondral injury after meniscal repair with bioabsorbable arrows

SUMMARY

Meniscal repair is a frequently performed procedure. Repair may be accomplished using several different techniques including inside-out, outside-in, and all-inside instrumentation. The Meniscus Arrow (Bionx, Blue Bell, PA) is an all-inside technique that has gained considerable popularity in the past 3 years. We report and illustrate a potential complication with this implant. Arrow fracture with condyle grooving should be considered in patients who have undergone repair with the Meniscus Arrow and complain of late postoperative symptoms.

Stroke and blood coagulation

A study of the coagulation parameters of 87 normal controls (ages 50 to 80) were compared with those of 33 patients with thrombotic stroke and 55 patients with diabetes mellitus of the same age distribution.

There were no significant differences when tested for the influence of sex or age.

Twenty-seven tests of clotting were done on each specimen, a total of 4,725.

Significant differences were detected between normals versus patients with thrombotic stroke (fibrinogen level, glass clotting time, silicone clotting time, heparin tolerance, platelet count and retarded thromboplastin generation time BaSO 4 1:50 dilution) and between normals versus patients with diabetes (prothrombin time, silicone clotting time, platelet count, thromboplastin generation time and retarded thromboplastin generation time) when subjected to computer analysis. The clinical significance of these differences is not of practical value in the diagnosis or as a guide to therapy for stroke.