The Hamstring/Quadriceps Ratio in Young Men and Its Relationship with the Functional Symmetry of the Lower Limb in Young Men

The relationship of muscle strength symmetry with the symmetry of dynamic activities such as vertical jump (CMJ) and with symmetry of ranges of motion is ambiguous. Therefore, the aim of the current investigation was to assess the relationship between the flexor/extensor strength ratio and the range of motion of the knee joints and VGRF during jump in a sample of young healthy men. The sample consisted of 64 healthy, active men. The flexor and extensor torques and ranges of active and passive mobility of both knee joints were measured. Vertical ground reaction force (VGRF) was measured using two platforms. There were no significant correlations between the symmetry of muscle strength and the symmetry of ranges of motion and the symmetry of the VGRF. Therefore, using the cluster analysis, 4 subgroups were distinguished due to the size of the flexor/extensor ratio (H/Q ratio). Significant differences were found in the level of strength of the knee flexors between the clusters. Detailed analysis of muscle strength symmetry and VGRF symmetry seem to confirm the Leading Joint Hypothesis theory of motion control in multi-joint systems. It was found that the process of controlling movement by the nervous system compensates for the small asymmetries in the level of muscle strength in the knee flexors and extensors, as well as small asymmetries of VGRF.

Functional Symmetry and Statistical Depth for the Analysis of Movement Patterns in Alzheimer’s Patients

Black-box techniques have been applied with outstanding results to classify, in a supervised manner, the movement patterns of Alzheimer’s patients according to their stage of the disease. However, these techniques do not provide information on the difference of the patterns among the stages. We make use of functional data analysis to provide insight on the nature of these differences. In particular, we calculate the center of symmetry of the underlying distribution at each stage and use it to compute the functional depth of the movements of each patient. This results in an ordering of the data to which we apply nonparametric permutation tests to check on the differences in the distribution, median and deviance from the median. We consistently obtain that the movement pattern at each stage is significantly different to that of the prior and posterior stage in terms of the deviance from the median applied to the depth. The approach is validated by simulation.

Analysis of the electronic structure of the primary electron donor of photosystem I of <i>Spirodela</i> <i>oligorrhiza</i> by photochemically induced dynamic nuclear polarization (photo-CIDNP) solid-state nuclear magnetic resonance (NMR)

The electron donor in photosystem I (PSI), the chlorophyll dimer P700, is studied by photochemically induced dynamic nuclear polarization (photo-CIDNP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) on selectively 13C and uniformly 15N labeled PSI core preparations (PSI-100) obtained from the aquatic plant duckweed (Spirodela oligorrhiza). Light-induced signals originate from the isotope-labeled nuclei of the cofactors involved in the spin-correlated radical pair forming upon light excitation. Signals are assigned to the two donor cofactors (Chl a and Chl a') and the two acceptor cofactors (both Chl a). Light-induced signals originating from both donor and acceptor cofactors demonstrate that electron transfer occurs through both branches of cofactors in the pseudo-C2 symmetric reaction center (RC). The experimental results supported by quantum chemical calculations indicate that this functional symmetry occurs in PSI despite similarly sized chemical shift differences between the cofactors of PSI and the functionally asymmetric special pair donor of the bacterial RC of Rhodobacter sphaeroides. This contributes to converging evidence that local differences in time-averaged electronic ground-state properties, over the donor are of little importance for the functional symmetry breaking across photosynthetic RC species.

Analysis of the electronic asymmetry of the primary electron donor of photosystem I of <i>Spirodela oligorrhiza</i> by photo-CIDNP solid-state NMR

The electron donor in photosystem I, the chlorophyll dimer P700, is studied by photo-CIDNP (photochemically induced dynamic nuclear polarization) MAS (magic-angle spinning) NMR on selectively 13C and uniformly 15N labeled PSI core preparations (PSI-100) obtained from the aquatic plant duckweed (Spirodela oligorrhiza). Light-induced signals originate from the isotope labelled nuclei of the cofactors involved in the spin-correlated radical pair forming upon light excitation. Signals are assigned to the two donor cofactors (Chl a and Chl a') and the two acceptor cofactors (both Chl a). Light induced signals originating from both donor and acceptor cofactors demonstrate that electron transfer occurs through both branches of cofactors in the pseudo-C2 symmetric Reaction Center (RC). The experimental results supported by quantum chemical calculations indicate that this functional symmetry occurs in PSI despite similarly sized chemical-shift differences between cofactors of PSI and the functionally asymmetric special-pair donor of the bacterial RC of Rhodobacter sphaeroides. This contributes to converging evidence that local differences in time-averaged electronic ground-state properties, over the donor are of little importance for functional symmetry breaking across photosynthetic RC species.

Asymmetric Functional Gradients in the Human Subcortex

ABSTRACTA central principle in our understanding of cerebral cortical organization is that homotopic left and right areas are functionally linked to each other, and also connected with structures that share similar functions within each cerebral cortical hemisphere. Here we refer to this concept as interhemispheric functional symmetry (IHFS). While multiple studies have described the distribution and variations of IHFS in the cerebral cortex, descriptions of IHFS in the subcortex are largely absent in the neuroscientific literature. Further, the proposed anatomical basis of IHFS is centered on callosal and other commissural tracts. These commissural fibers are present in virtually all cerebral cortical areas, but almost absent in the subcortex. There is thus an important knowledge gap in our understanding of subcortical IHFS. What is the distribution and variations of subcortical IHFS, and what are the anatomical correlates and physiological implications of this important property in the subcortex? Using fMRI functional gradient analyses in a large dataset (Human Connectome Project, n=1003), here we explored IHFS in human thalamus, lenticular nucleus, cerebellar cortex, and caudate nucleus. Our detailed descriptions provide an empirical foundation upon which to build hypotheses for the anatomical and physiological basis of subcortical IHFS. Our results indicate that direct or driver cerebral cortical afferent connectivity, as opposed to indirect or modulatory cerebral cortical afferent connectivity, is associated with stronger subcortical IHFS in thalamus and lenticular nucleus. In cerebellar cortex and caudate, where there is no variability in terms of either direct vs. indirect or driver vs. modulatory cerebral cortical afferent connections, connectivity to cerebral cortical areas with stronger cerebral cortical IHFS is associated with stronger IHFS in the subcortex. These two observations support a close relationship between subcortical IHFS and connectivity between subcortex and cortex, and generate new testable hypotheses that advance our understanding of subcortical organization.

FEMORAL NERVE CATHETER IS ASSOCIATED WITH PERSISTENT STRENGTH DEFICITS AT 6 MONTHS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN PEDIATRIC PATIENTS

Background: The long-term outcomes of femoral nerve blockade following ACL reconstruction are not well defined. Femoral nerve blocks are typically administered as either a single-injection nerve block (FNB) or a continuous femoral nerve catheter (FNC). Prior work among pediatric patients found knee extension and flexion strength deficits 6 months postoperatively using FNB. However, this work was limited by the use of multiple graft choices and orthopedic surgeons. Purpose/Hypothesis: The purpose of this study was to investigate functional recovery after primary ACL surgery with quadriceps tendon-patellar autograft (QPA) in patients receiving a sciatic nerve block and either FNB or FNC. Our hypothesis was that short-term functional performance would be worse among those who underwent FNC compared to FNB. Methods: We conducted a retrospective chart review of pediatric patients 10-19 years of age who underwent ACL reconstruction with QPA by a single orthopedic surgeon. Surgery was performed at two locations: one of which administered FNB and the other FNC. Both were combined with sciatic nerve block. A physical therapist performed functional asymmetry assessments at approximately 6 months postoperative. We compared single-leg squat symmetry between groups using independent samples t-tests. We compared the proportion of patients in each group who achieved 80% symmetry on single-leg squat and Y-Balance tests, had initiated ballistics and running programs, and demonstrated functional symmetry at the 6-month post-operative appointment using Chi-square analyses. Results: Demographics were similar between groups (Table 1). Single leg percent symmetry of the operative limb was significantly greater in the FNB group compared to the FNC group (Table 2). In addition, a greater proportion of those in the FNB group demonstrated functional symmetry compared to the FNC group during the 6-month assessment (Table 2). There were no proportional differences between the groups for the number of patients who demonstrated 80% symmetry during single-leg squat or Y-Balance test, or had initiated a ballistics or running program at the time of assessment. Conclusion: Pediatric patients in the FNC group demonstrated poorer single-leg squat symmetry and functional symmetry compared to those in the FNB group at 7 months following ACL reconstruction with QPA. These preliminary findings may relate to increased concentration and duration of local anesthetic in the FNC group postoperatively. Providers should be cognizant of the implications of FNC on long-term outcomes of ACL reconstruction. [Table: see text][Table: see text]