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

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

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

Health inequities: lower socio-economic conditions and higher incidences of intestinal parasites

<p>Abstract</p> <p>Background</p> <p>Intestinal parasitic infections affect child health and development and slow down growth, while reducing adults' productivity and work capacity. The aim of the present study was to determine and compare the incidences of intestinal parasitic infections and the socio-economic status of two near primary school children in Manisa, a western city of Turkey.</p> <p>Methods</p> <p>A total of 352 children were involved a questionnaire study from a private school (Ülkem Primary School – ÜPS, 116 children) and a community-based school (Şehzadeler Primary School – ŞPS, 236 children). Of these, stool samples could be obtained from a total of 294 students; 97 (83.6%) from ÜPS, and 197 (83.5%) from ŞPS. The wet mount preparations of the stool samples were examined; samples were also fixed in polyvinyl alcohol and examined with modified formalin ethyl acetate sedimentation and trichrome staining techniques. Data were analyzed using SPSS for Windows version 10.0. The chi-squared test was used for the analytic assessment.</p> <p>Results</p> <p>The percentages of the students found to be infected with intestinal parasites, were 78 (39.6%) and 13 (13.4%) in ŞPS and ÜPS, respectively. Totally 91 (31.0%) of the students from both schools were found to be infected with at least one intestinal parasite. <it>Giardia lamblia </it>was found to be the most common pathogenic intestinal parasite and <it>Blastocystis hominis </it>was prevalent independently from the hygienic conditions. The factors which significantly (<it>p </it>< 0.05) increase the incidence of intestinal parasites were uneducated and unemployed mother, lower social status of father, living in crowded houses with insufficient indoor spaces, using the tap water as drinking water, and living at shanty areas.</p> <p>Conclusion</p> <p>Intestinal parasitic infections in school children were found to be a public health problem that increased due to lower socio-economic conditions. We conclude that organization of education seminars including the topics such as prevention of the infectious diseases, improving general hygienic conditions, and application of supportive programs for the parents may be suggested not only to reduce intestinal parasitic infections, but also to elevate the socio-cultural levels.</p

Evaluation and extension of the cognitive assistant system (COGAS) for user-oriented support of air target identification

Combat Information Centres (CIC) of German Navy ships are equipped with highly advanced command and control systems. Due to different task domains the command and control processes are characterized by a high complexity that might affect the operators' workload and consequently the error rate in the workflow. In addition, the command and control systems, which are controlled with a high level of automation, do not provide complete reliability in complex conflict situations. Given the lack of competency and skills expected by demographic change and the suspension of compulsory military services, a computer based support of these command and control processes e.g. in the form of cognitive assistant systems seems advisable. Systems with cognitive capabilities have gained importance over the past 30 years. They can increasingly support complex work and decision processes. For the application of cognitive technologies in assistant systems it is important to design user oriented support functionalities and provide the compatibility between the human operator and the technical system. This paper describes the evaluation and examines the extension of a cognitive assistant system (COGAS) developed in a simulation study to support the air target identification on German navy ships

Comparison of eosin and HOS test methods in assessment of sperm viability in asthenozoospermia cases [Astenozoospermi olgularinda semende canlilik testinin degerlendirilmesinde eozin ve HOS testlerinin karşilaştirilmasi]

Objective: This study investigated whether one of the two viability tests is superior to the other in cases with asthenozoospermia (reduced sperm motility) in which the rate of immotile spermatozoa exceeded 50%. Materials and Methods: A total of 21 male patients who visited the IVF (in vitro fertilization) unit of the Department of Obstetrics and Gynecology of Dokuz Eylül University Medical Faculty were included in the study. Semen samples were subjected to both macroscopic and microscopic examinations. Makler counting chamber was used for the sperm motility and concentration analyses. All semen samples were subjected to eosin viability test and HOS (hypo-osmolar swelling) test. The result of the eosin test was accepted as normal in the case of presence of 75% or more unstainable spermatozoa in a semen sample. The result of the HOS test was accepted as normal if swelling behavior were observed in more than 60% of the spermatozoa tails in a semen sample. Results: Both tests yielded normal results in 10 cases, while the test results were found to be abnormal in 4 of the cases. In 7 cases, the HOS test yielded abnormal results, while the results of the eosin test were found to be normal. The binomial (sign test) statistical evaluation revealed that the two tests have no superiority over one another (p>0.05). Discussion: The fact that the HOS test as a viability test yielded very similar results when compared to the eosin test demonstrates the significance of the HOS test in the sense that it is economic