Amyotrophic lateral sclerosis weakens spinal recurrent inhibition and post-activation depression

Objectives: Amyotrophic lateral sclerosis (ALS) disrupts motoneurons that control movement and some vital functions, however, exact details of the neuronal circuits involved in ALS have yet to be fully endorsed. To contribute to our understanding of the responsible neuronal circuits, we aimed to investigate the spinal recurrent inhibition (RI) and post-activation depression (P-AD) in ALS patients. / Methods: In two groups of ALS patients, i.e. lumbar-affected (clinical signs in leg muscles) and nonlumbar-affected (clinical signs in arms or bulbar region but not in the legs), RI and P-AD on the soleus muscle were investigated using single motor units and amplitude changes of H-reflex in surface electromyography, respectively. The data were compared with healthy subjects. / Results: Compared to controls, P-AD of H-reflex was reduced severely in lumbar-affected patients and reduced to a certain degree in nonlumbar-affected patients. Similarly, a significant reduction in the duration of RI on firing motoneurons was found in lumbar-affected patients (11.5 ± 2.6 ms) but not in nonlumbar-affected patients (29.7 ± 12.4 ms, P<0.0001) compared to controls (30.8 ± 7.2 ms, P<0.0001). / Conclusion: The current study revealed that spinal inhibitory circuits are impaired in ALS. / Significance: These findings may provide insight for proposing new therapeutic approaches and following disease progression in humans

Motor units as tools to evaluate profile of human Renshaw inhibition

Although Renshaw inhibition (RI) has been extensively studied for decades, its precise role in motor control is yet to be discovered. One of the main handicaps is a lack of reliable methods for studying RI in conscious human subjects. We stimulated the lowest electrical threshold motor axons (thickest axons) in the tibial nerve and analysed the stimulus‐correlated changes in discharge of voluntarily recruited low‐threshold single motor units (SMUs) from the soleus muscle. In total, 54 distinct SMUs from 12 subjects were analysed. Stimuli that generated only the direct motor response (M‐only) on surface electromyography induced an inhibitory response in the low‐threshold SMUs. Because the properties of RI had to be estimated indirectly using the background discharge rate of SMUs, its profile varied with the discharge rate of the SMU. The duration of RI was found to be inversely proportional to the discharge rate of SMUs. Using this important finding, we have developed a method of extrapolation for estimating RI as it develops on motoneurons in the spinal cord. The frequency methods indicated that the duration of RI was between 30 and 40 ms depending on the background firing rate of the units, and the extrapolation indicated that RI on silent motoneurons was ∼55 ms. The present study establishes a novel methodology for studying RI in human subjects and hence may serve as a tool for improving our understanding of the involvement of RI in human motor control

Post-activation depression of primary afferents reevaluated in humans

Amplitude variation of Hoffmann Reflex (H-reflex) was used as a tool to investigate many neuronal networks. However, H-reflex itself is a subject to intrinsic changes including post-activation depression (P-AD). We aimed to investigate P-AD and its implication on motor control in humans. Upon tibial nerve stimulation in 23 healthy participants, peak-to-peak amplitude change of H-reflex was investigated using surface electromyography (SEMG) of soleus muscle. Variety of stimulus intensities, interstimulus intervals (ISIs), voluntary contraction levels/types and force recording were used to investigate the nature of P-AD. We have shown that P-AD was significantly stronger in the shorter ISIs. The only exception was the ISI of 200 msecs which had a weaker P-AD than some of the longer ISIs. Sudden muscle relaxation, on the other hand, further increased the effectiveness of the ongoing P-AD. Moreover, P-AD displayed its full effect with the first stimulus when there was no muscle contraction and was efficient to reduce the muscle force output by about 30%. These findings provide insight about the variations and mechanism of P-AD and could lead to improvements in diagnostic tools in neurological diseases

The effect of oral administration of monosodium glutamate on epileptogenesis in infant rats

Aim: Glutamate is an excitatory neurotransmitter that is widely distributed throughout the brain. An increase in glutamate concentration or sensitivity of glutamate receptors triggers neurodegenerative diseases, epilepsy in particular. Monosodium glutamate is a substance added to foods to enhance flavour. We investigated the effect of monosodium glutamate on epileptogenesis, as well asheight and weight, in rats that were just weaned. Methods: Twenty-four male and female 21-day-old Wistar Albino rats were divided into two groups: one with monosodium glutamate added to the drinking water, and a control in which NaCl was added to the drinking water. The electrical stimulation threshold values were determined in animals to which the hippocampal kindling process was applied, and the stimulations at these threshold values were invariably applied to the animals until they were kindled. Results: The electrical stimulation threshold values of the monosodium glutamate group did not statistically change, whereas the number of required stimulations for kindled rats was significantly lower compared with the control group. Conclusion: These results reveal that long-term oral administration of glutamate salts causes an increase in excitability in the central nervous system during ontogenetic development. © 2020 Epileptic Disorder

Effect of aging on H-reflex response to fatigue

Injury as a result of tripping is relatively common among older people. The risk of falling increases with fatigue and of importance is the ability to dorsiflex the foot through timely activation of the tibialis anterior (TA) muscle to ensure the foot clears the ground, or an obstacle, during the swing phase of walking. We, therefore, questioned whether the muscle spindle input to the motoneurons alters with ongoing fatigue in older people. We electrically stimulated the common peroneal nerve to assess the TA primary afferent efficacy using H-reflex before, immediately following and after a fatiguing maximal isometric contraction. M-response was kept unchanged throughout the experiment to ensure a similar stimulus intensity was delivered across time points. H-reflex increased significantly while the TA muscle was in a state of fatigue for the younger participants but tended to decrease with increasing age. The main contributor to the tonicity of TA muscle, i.e., excitatory synapses of spindle primary endings of motoneurons that innervate TA muscle, tend to lose their efficacy during fatigue in the older individuals but increased efficiency in the majority of the younger people. Since TA muscle is the main dorsiflexor of the foot and it needs to be active during the swing phase of stepping to prevent tripping, older individuals become more susceptible to falling when their muscles are fatigued. This finding may help improve devices/treatments to overcome the problem of tripping among older individuals

Exploring the receptor origin of vibration-induced reflexes

STUDY DESIGN: An experimental design. OBJECTIVES: The aim of this study was to determine the latencies of vibration-induced reflexes in individuals with and without spinal cord injury (SCI), and to compare these latencies to identify differences in reflex circuitries. SETTING: A tertiary rehabilitation center in Istanbul. METHODS: Seventeen individuals with chronic SCI (SCI group) and 23 participants without SCI (Control group) were included in this study. Latency of tonic vibration reflex (TVR) and whole-body vibration-induced muscular reflex (WBV-IMR) of the left soleus muscle was tested for estimating the reflex origins. The local tendon vibration was applied at six different vibration frequencies (50, 85, 140, 185, 235, and 265 Hz), each lasting for 15 s with 3-s rest intervals. The WBV was applied at six different vibration frequencies (35, 37, 39, 41, 43, and 45 Hz), each lasting for 15 s with 3-s rest intervals. RESULTS: Mean (SD) TVR latency was 39.7 (5.3) ms in the SCI group and 35.9 (2.7) ms in the Control group with a mean (95% CI) difference of -3.8 (-6.7 to -0.9) ms. Mean (SD) WBV-IMR latency was 45.8 (7.4) ms in the SCI group and 43.3 (3.0) ms in the Control group with a mean (95% CI) difference of -2.5 (-6.5 to 1.4) ms. There were significant differences between TVR latency and WBV-IMR latency in both the groups (mean (95% CI) difference; -6.2 (-9.3 to -3.0) ms, p = 0.0001 for the SCI group and -7.4 (-9.3 to -5.6) ms, p = 0.011 for Control group). CONCLUSIONS: The results suggest that the receptor of origin of TVR and WBV-IMR may be different

Double vs single internal thoracic artery harvesting in diabetic patients: role in perioperative infection rate

Background: The aim of this prospective study is to evaluate the role in the onset of surgical site infections of bilateral internal thoracic arteries harvesting in patients with decompensated preoperative glycemia. Methods: 81 consecutive patients with uncontrolled diabetes mellitus underwent elective CABG harvesting single or double internal thoracic arteries. Single left ITA was harvested in 41 patients (Group 1, 50.6%), BITAs were harvested in 40 (Group 2, 49.4%). The major clinical end points analyzed in this study were infection rate, type of infection, duration of infection, infection relapse rate and total hospital length of stay. Results: Five patients developed sternal SSI in the perioperative period, 2 in group 1 and 3 in group 2 without significant difference. All sternal SSIs were superficial with no sternal dehiscence. The development of infection from the time of surgery took 18.5 ± 2.1 and 7.3 ± 3.0 days for Groups 1 and 2 respectively. The infections were treated with wound irrigation and debridement, and with VAC therapy as well as with antibiotics. The VAC system was removed after a mean of 12.8 ± 5.1 days, when sterilization was achieved. The overall survival estimate at 1 year was 98.7%. Only BMI was a significant predictor of SSI using multivariate stepwise logistic regression analysis (Odds Ratio: 1.34; 95%Conficdence Interval: 1.02–1.83; p value: 0.04). In the model, the use of BITA was not an independent predictor of SSI. Conclusion: CABG with bilateral pedicled ITAs grafting could be performed safely even in diabetics with poor preoperative glycaemic control

Competition for conservation: Observation of 1ST prussian carp carassius gibelio (bloch, 1782) catching competition in gokpinar dam pond (Denizli/Turkey)

2-s2.0-85091679865In this study, it was aimed to examine socioeconomic conditions and reasons for participating in the 1st Prussian Carp Catching Competition, organized by Denizli Amateur Sportive Hand-line Fishers and Fishery Protection Association (DENOLDER) in Denizli Gokprnar Dam Pond. This organization, supported by Amateur Sportive Hand-line Fishing Federation and Denizli Metropolitan Municipality, has the purpose of introducing, ingratiating and binding hand-line fishing fanciers, also additionally and most importantly, raising awareness in the society for damages of ecologically harmful species to aquatic life, in our inner waters. A questionnaire was used, in order to conduct a direct interviewing of the individuals participating in the 1st Prussian Carp Catching Competition, and the original study data was obtained. The questionnaire consisted of 23 questions. The questionnaire results were evaluated, using The Statistical Package for the Social Sciences (SPSS) and EXCEL package programs. In total, 49 individuals filled in the questionnaire, in this competition, with a participation of 55 teams from six provinces. Moreover, all teams indicated that they would participate again, in case of a repetition of such an organization. It is essential to protect fishes, having an important place within fishery products, particularly natural species. It should be our responsibility to raise public awareness relating to invasive species. © 2020 Parlar Scientific Publications. All rights reserved