Gait speed is more challenging than cognitive load on the stride-to-stride variability in individuals with anterior cruciate ligament deficiency

Background

Several investigations have studied gait variability of individuals with anterior cruciate ligament (ACL) deficiency; however, the effect of dual-tasking on the gait variability of these individuals remained unclear. The aim of the present study was to determine the effect of gait speed and dual-tasking on knee flexion–extension variability in subjects with and without ACL deficiency.

Electrical Low Frequency Stimulation of the Kindling Site Preserves the Electrophysiological Properties of the Rat Hippocampal CA1 Pyramidal Neurons From the Destructive Effects of Amygdala Kindling: The Basis for a Possible Promising Epilepsy Therapy

BackgroundDeep brain stimulation (DBS) has emerged as a potential therapeutic strategy in the treatment of neurological disorders including epilepsy. However, the cellular mechanism responsible for the effects of DBS remains largely undefined. Therefore, using electrophysiological approach, we aimed to determine the antiepileptic effects and restorative potential of low frequency stimulation (LFS) on amygdala kindling-induced changes in electrophysiological properties of rat hippocampal CA1 pyramidal neurons.MethodsAnimals were kindled by electrical stimulation of amygdala in a rapid kindling manner (12 times per day). In one group of animals, immediately after termination of daily 12 rapid kindling stimulations, the kindling site was subjected to 4 packages of LFS at intervals of 5 min (each package contained 200 monophasic square-wave pulses, 0.1 ms pulse duration at 1 Hz). Whole cell patch clamp recording under current clamp conditions was performed on visually identified pyramidal neurons in hippocampal slice preparations obtained from amygdala-kindled rats and the rats receiving LFS.ResultsKindling of the right basolateral amygdala profoundly affected spontaneous firing behavior and repetitive discharge characteristics of pyramidal neuronal electrophysiological properties. Application of LFS at the kindling site almost completely prevented the development of epilepsy and the disruptive effects of kindling on neuronal electrical activity through restoration of the normal electrophysiological characteristics.ConclusionsThe results of this study implied that application of LFS during kindling acquisition prevents the kindling induced changes in functional electrical properties of CA1 pyramidal neurons, suggesting that this action may be involved in the antiepileptogenic mechanism of LFS.     

The effects of cognitive loading on balance control in patients with multiple sclerosis

The aim of this study was to compare the effects of concurrent cognitive task (silent backward counting) on balance performance between two groups of multiple sclerosis (MS) (n = 23) and healthy (n = 23) participates. Three levels of postural difficulty were studied on a force platform, i.e. rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed. A mixed model analysis of variance showed that under difficult sensory condition of foam surface with eyes closed, execution of concurrent cognitive task caused a significant decrement in variability of sway velocity in anteroposterior direction for the patient group (P < 0.01) while this was not the case for healthy participants (P = 0.22). Also, the variability of sway velocity in mediolateral direction was significantly decreased during concurrent execution of cognitive task in patient group (P < 0.01) and not in healthy participants (P = 0.39). Furthermore, in contrast to single tasking, dual tasking had the ability to discriminate between the 2 groups in all conditions of postural difficulty. In conclusion, findings of variability in sway velocity seem to confirm the different response to cognitive loading between two groups of MS and healthy participants.     

Collagen mutation causes changes of the microdamage morphology in bone of an OI mouse model

Previous studies have postulated that ultrastructural changes may alter the pattern and capacity of microdamage accumulation in bone. Using an osteogenesis imperfecta (OI) mouse model, this study was performed to investigate the correlation of collagen mutation with the microdamage morphology and the associated brittleness of bone. In this study, femurs from mild OI and wild type mice were fatigued under four-point bending to create microdamage in the specimens. Then, the microdamage morphology of these specimens was examined using the bulk-staining technique with basic fuchsin. Similar with the results of previous studies, it was observed that linear microcracks were formed more easily in compression, whereas diffuse damage was induced more readily in tension for both wild-type and mild-type mice. However, less diffuse damage was found in the tensile side of mild OI mouse femurs (collagen mutation) compared with those of wild type mice, showing that the microdamage morphology is correlated to the brittleness of bone. The results of this study provide direct evidence that supports the prediction made by the previous numerical simulation studies, suggesting that microdamage morphology in bone is significantly correlated with the integrity of the collagen phase.     

Psychotropic medications and the risk of fracture: a meta-analysis.

BACKGROUND: Older adults throughout the developed world are at significant risk of osteoporotic fractures. Many studies have examined the relationship between the use of psychotropic medications and the risk of fractures, but these studies have reported conflicting results. PURPOSE: To resolve discrepancies, we carried out a meta-analysis to assess the risk of fractures among users of several classes of psychotropic drugs. DATA SOURCES: We retrieved studies published in any language by systematically searching MEDLINE, LILACS, EMBASE and ISI Proceedings databases and by manually examining the bibliographies of the articles retrieved electronically as well as those of recent reviews. STUDY SELECTION: We included 98 cohort and case-control studies, published in 46 different articles, that reported relative risk (RR) estimates and confidence intervals (CIs) or sufficient data to calculate these values. DATA SYNTHESIS: Study-specific RRs were weighted by the inverse of their variance to obtain fixed- and random effects pooled estimates. The random effects RR of fractures was 1.34 (95% CI 1.24, 1.45) for benzodiazepines (23 studies), 1.60 (95% CI 1.38, 1.86) for antidepressants (16 studies), 1.54 (95% CI 1.24, 1.93) for non-barbiturate antiepileptic drugs (13 studies), 2.17 (95% CI 1.35, 3.50) for barbiturate antiepileptic drugs (five studies), 1.59 (1.27, 1.98) for antipsychotics (12 studies), 1.15 (95% CI 0.94, 1.39) for hypnotics (13 studies) and 1.38 (95% CI 1.15, 1.66) for opioids (six studies). For non-specified psychotropic drugs (10 studies), the pooled RR was 1.48 (95% CI 1.41, 1.59). LIMITATIONS: Main concerns were the potential for residual confounding and for publication bias. CONCLUSION: Globally, the increase in the risk of fractures among psychotropic drug users is moderate. Further research is needed, especially to examine high-risk populations and newer medications. Future studies should be prospective and emphasise control of confounding bias.