Axonal excitability and conduction alterations caused by levobupivacaine in rat

In this study, effects of the long-acting amide-type local anesthetic levobupivacaine on axonal conduction and excitability parameters of the rat sciatic nerve were thoroughly examined both in vitro and in vivo. In order to deduce its effects on isolated nerve conduction, compound nerve action potential (CNAP) recordings were performed using the suction method over sciatic nerves of Wistar rats before and after administration of 0.05 % (1.7 mmol L–1) levobupivacaine. Levobupivacaine caused complete CNAP area and amplitude depression by blocking conduction in a time-dependent manner. To assess the influence of levobupivacaine on in vivo excitability properties, threshold-tracking (TT) protocols were performed at sciatic nerves of rats injected with perineural 0.05 % (1.7 mmol L–1) levobupivacaine or vehicle alone. Charge-duration TT results revealed that levobupivacaine increases the rheobase and decreases the strength-duration time constant, suggesting interference of the anesthetic with the opening of Na+ channels. Twenty and 40 % threshold electrotonus curves were found for both groups to follow the same paths, suggesting no significant effect of levobupivacaine on K+ channels for either the fastest or relatively slow conducting fibers. Current-threshold relationship results revealed no significant effect on axonal rectifying channels. However, according to the results of the recovery cycle protocol yielding the pattern of excitability changes following the impulse, potential deviation was found in the recovery characteristics of Na+ channels from the absolute refractory period. Consequently, conduction blockage caused by levobupivacaine may not be due to the passive (capacitive) properties of axon or the conductance of potassium channels but to the decrease in sodium channel conductance

A Comparative of Finger Tapping Test Scores Elite Athletes, Art, Foreign Languages and Computer- Instructional Technology Students

Fine motor skill is ability to control and coordinate the small muscles in the hand for precise movements. Fine motor skill have been associated with several other cognitive abilities, including processing speed executive functions and scholastic skills. Fine motor skill in the early years have also been shown to predict later academic achievement, especially in reading and mathematics and to predict underachievement in able students at school. In this aspect our objective in this study was to compare finger tapping test scores between students of art, foreign languages, computer-instructional technologies and elite athletes. A significant difference was found between elite athletes and all groups in finger tapping test scores. Elite athletes performed more finger taps than other groups in the same period. In conclusion, the more importance of fine motor skill in terms of sporting success also explains the difference of the finger tapping test performances between the groups. Keywords: education, motor skills, finger tapping, elite athlete

Distribution of Dynamic Forces on Patient Specific Vascular Model:Application of computational Hemodynamics

Objective: Recent advances in computerized image processing made the early diagnosis and elective invasive treatment of vascular pathologies possible. However, studies state that the complication rates of elective procedures are higher thatn that the of untreated cases. And, making the decision between protection from life threatening complications and unnecessary interventions is a controversial issue. Therefore, recent studies put emphasis on multidisciplinary motivation,; consequently "computational fluid dynamics" took place in medical simulations. With the aim of setting up hemodynamic forces were discussed in vascular models. Methods: Three dimensional distribution of hmodynamic forces in aneurisam and stenotic models were computed by uisng two different patient specific simulations which were constructed on two different vessel models of "parametric" and "realistic" approaches. Results: The results were consistent with almost all common practical knowledge. Continuity and Bernoulli's laws imply that a fluid moving through a wide vessel must move more quickly when the vessel narrows and the pressure decreases gradually. The relation between vessel geometry and velocity vectors in maintained laminor flow conditions was demonstrated. The impacts of radial forces and vessel wall structure on spatial distribution of the displacement in vessel geometry were also shown. Additionally spatial distribution of the axial force of "wall shear stress" which was recently suggested to be a hightly reliable measure was evaluated. Conclusion: Patient specific simulations that are belived to be the core of the future project of "clinical diagnostic expert systems" will be an important tool; in prescribing patient specific treatment and in the assessment of complications risks

Axonal excitability and conduction alterations caused by levobupivacaine in rat

In this study, effects of the long-acting amide-type local anesthetic levobupivacaine on axonal conduction and excitability parameters of the rat sciatic nerve were thoroughly examined both in vitro and in vivo. In order to deduce its effects on isolated nerve conduction, compound nerve action potential (CNAP) recordings were performed using the suction method over sciatic nerves of Wistar rats before and after administration of 0.05 % (1.7 mmol L−1) levobupivacaine. Levobupivacaine caused complete CNAP area and amplitude depression by blocking conduction in a time-dependent manner

The Impacts of Central Fatigue on the Polyphasic Nature of Tapping Performance

Objective: As a non-specific symptom muscle fatigue mostly accompanies neuromuscular diseases and also occurs frequently in healthy individuals. Fatigue phenomenon is considered to be multidimensional symptom. There have been still discussions on the origin whether it depends primarily on the intrinsic properties of muscle itself (peripheral mechanisms) or the nervous system that controls muscle (central mechanisms). This study aimed to investigate the effects of central fatigue on the performance of maximal voluntary repetitive movement and discusses the specificity of finger tapping task test as a simple diagnostic tool for fatigue. Methods: For this purpose, 27 healthy, male, right-handed volunteer performed the 20-s of finger tapping task test for four times. The one was for control and the other three were performed right after induction of three different central fatigue models. Temporal behavior of tapping performances were evaluated based on inter-tap intervals and the statistical comparison were made by regression analysis. Results: The results showed that the partial evaluation of the task in time domain instead of complete test period yielded with statistically significant differences between control and fatigue models (p<0.001) and even in between the fatigue models. Conclusion: Approximately the first 5-s of a finger tapping task consists of both motor learning processes and dynamics of energy consumption from anaerobic sources. However, it reflects dominantly the central components of fatigue. We may conclude that the temporal behavior of tapping performance following the induction of specific fatigue model may help making further discrimination for the origin of fatigue