Research has shown that skeletal muscle, despite showing a high degree of specialisation, has a remarkable ability to modif,' its properties. Understanding these changes is important for optimal response to therapeutic intervention. These studies investigated alterations in neuromuscular performance of quadriceps femoris muscle in normal subjects, before investigating changes in muscle and neural mechanisms in the first six months following stroke. Muscle ftinction studies were conducted to monitor the effects of selected patterns of long term electrical stimulation (P1 - uniform 8 Hz, P2 - mixed frequency, and P3 random high and low frequency) on quadriceps femoris of2l healthy subjects. Stimulated muscles showed significant increases in strength, fatigue resistance and relaxation times after 3 weeks and in force-frequency output after 6 weeks. Significant changes were observed in the stimulated muscles in Groups P2 and P3 indicating that a mixed or random pattern of activation induced greater changes than a uniform 8 Hz pattern. These studies together with soleus H reflexes were used to study concurrent changes in quadriceps femoris and Ta spinal reflex pathways of stroke patients and age-matched controls (n=1O). One month following stroke, both paretic and non-paretic muscles were more fatiguable and weaker than the muscles of controls and disynaptic and presynaptic inhibition were reduced in the paretic limbs. In subsequent months, the paretic muscles regained strength and inhibitory effects were restored. Subjective analysis suggested that different patterns of recovery related to walking ability at six months. In patients taking less than 15s to walk lOm (Group 1 n=5), the paretic muscles became significantly stronger and less fatiguable over time whereas the muscles of patients who took longer to walk lOm (Group 2 n=5) remained weaker and more fatiguable. Reciprocal inhibition was regained by 1 month in Group 1 and by 6 months in Group 2. These findings provide insight into long-term recovery and rationale for therapeutic intervention following stroke.

Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2017. / Background to the study: Chronic low back pain (CLBP) is a common musculoskeletal complaint, which results in increased absenteeism from work and other disabilities. Interferential current (IFC) is one of the treatment modalities used by manual and physical therapists to alleviate CLBP. Interferential current involves electrical stimulation of medium frequency using two currents that cross over each other. There have been numerous mechanisms proposed on how IFC works with regard to pain inhibition; however, these remain unconfirmed. Common theories include those based on the gate control theory of pain and integrated pain theories. Although the placement of the electrodes used in the IFC application has been well defined, the optimum treatment time for CLBP has not been well researched. Therefore, this study aimed to determine what protocol regarding the duration of IFC is most appropriate in the treatment of CLBP. Aim: The aim of this study was to investigate the effect of interferential current in the treatment of chronic low back pain using variable time intervals Methodology: This study was a randomised single-blinded clinical trial which consisted of 45 participants residing in the eThekwini municipality, divided into three groups of 15 each. The participants were randomly assigned using concealed allocation to one of three treatment groups of 15 each viz. 15, 20 or 30 minutes of interferential current (IFC). Low back pain level was determined using a numerical pain rating scale (NRS-101). Pain pressure thresholds (PPT) were measured with a pain pressure algometer. The effect of low back pain on participants’ activities of daily living was assessed using the Oswestry low back questionnaire (OLBQ).The participants received three treatments over a two week period with the fourth consultation being used for the final subjective and objective measurements a week later. Results: Repeated measures ANOVA testing was used to examine the intra-group effect of time and the inter-group effect of treatment on the outcomes of NRS-101 and algometer readings. Profile plots were used to assess the direction and trends of the effects. An intra-group analysis revealed that, objectively and subjectively, all groups responded positively to treatment over time, with no significant time-group interaction. Conclusion: This study concluded that neither group is more effective than the other with respect to participants’ pain perception and the OLBQ. However, groups one and three showed the largest individual improvement between consultation one and three, compared to group two which showed consistent improvement throughout for the NRS-101 readings. Based on the results collected from this study, the shortest time frame of 15 minutes of IFC application can be used in the treatment of CLBP. / M

No description available.

Mathematical models have been used to study the effects of various electrical stimuli on nerve. The applicability of the findings to electrocutaneous stimulation in man has been investigated experimentally. With the model of a nerve membrane the influence of variations in the stimulus parameters have been investigated. This was done for multiple bipolar pulses by considering selected cases and for single bipolar pulses with a systematic investigation. The main findings were i) that the threshold charge for a single bipolar pulses changes only slightly for different pulsewidths; ii) that the threshold charge monotonically decreases with pulsewidth and threshold charge also decreases monotonically with increasing delay of the symmetric negative pulse; iii) that threshold amplitude for multiple bipolar pulses was only slightly lower than the amplitude for a single bipolar pulse. The influence of different components involved in cutaneous stimulation, such as skin, electrode, and neuroanatomy, have been examined. Corresponding models for the passive components involved were selected. From these models the following limiting conditions for the stimulus were derived: i) the stimulus has to be current regulated; ii) it must be bipolar (no net charge transfer); and iii) the electrode voltage must remain below the skin break-down voltage. The aspect of the conversion of stimulus' energy into heat in the skin has been examined in detail. A review of mathematical models of the active nerve membrane is presented and the applicability of a nerve model to the stimulation of peripheral nerve fibres in man is discussed. Numerical methods were used to solve the model's differential equations. The effects on the solution of different integration methods and of different integration step sizes has been assessed. Experiments with electrocutaneous stimulation have been performed using single bipolar current stimuli. The duration of a pulse was less than 100 microseconds. For the experiments, an electrically isolated stimulator has been designed and built. It operated under the control of a PDP-12 computer. The sensations produced were slightly suprathreshold and painless. The thenar region of the hand was stimulated using a concentric electrode. The results of the experiments supported the theoretical predictions and indicated the possibility of using models to investigate the optimization of stimulus parameters within the range tested. The close correspondence between the experimental results and the nerve model calculations seems to provide some evidence for the hypothesis that in electrocutaneous stimulation the nerve fibres are stimulated directly. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The main purpose of this study was to observe the changes in muscular strength and endurance of the extensor muscles of the hand after the arm had been exposed to electrical stimulation. Twenty-four university students were chosen for this study. The subjects were divided into three groups of eight,, attempting to make each group homogeneous with respect to their Maximal Voluntary Iscitetric Contraction of the extensor muscles of the hand. All subjects were trained with the hand at 150 degrees with respect to the forearm (Position 1) . Group 1 (ES) received five minutes of electrical stimulation to the dorsal surface of the forearm each weekday for a four week period. The placement of the electrodes were at the musculotendonous area of the extensor muscles of the hand. The intensity of the faradic stimulation was just below the subjects pain threshold. Each contraction elicited by the electrical stimulation was for a duration of 880 msec, and the relaxation between each contraction was 1030 msec. Group 2 (VI) performed four sets of eight Maximal Voluntary Contractions, where each contraction was held for a duration of two seconds. Training took place on the Monday, Wednesday, and Friday of each week for a four week duration. Group 3 (ES+VIj performed the training of Groups 1 and 2 for four weeks. Subjects were tested for their Maximal Voluntary Contraction in both Position 1 and Position 2 (180 degrees with respect to the forearm). Endurance was calculated on the subjects fatigue curve. The time in seconds to 65% of their MVC (for each testing period) was used as a measure of their relative endurance. The testing of strength and endurance was done before any training took place, after two weeks of training, and at the duration of the four week period. Significant strength gains occurred in all three groups between the Pre test and Mid-Post in Position 1 and Position 2. During the Mid-Post training period only the ES+VI group had significant strength gains in Position 1; whereas in Position 2 both the ES and ES+VI groups yielded significant strength gains. It was illustrated that individual strength gains in the ES and VI groups were not additive in either position tested, and that one training method is not significantly better than another when observing mean strength gains over time. During the four week training period the endurance of the muscles did not alter significantly when locking at the mean of all three groups. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Simona Dudičová Supervisor: Assoc. Prof. PharmDr. Martina Čečková, Ph.D. Title of diploma thesis: The effect of in vitro and ex vivo placental cells stimulation on expression of selected ABC and OATP transporters The placenta is an organ that plays a key role throughout pregnancy for proper fetal development. One of the important functions provided by the placenta is the transport of substances between the mother and the fetus. This transfer of substances enabled mainly by membrane transporters, which are located on the apical and basal membranes of the syncytiotrophoblast. During various physiological or pathological changes in the human body, their expression and amount can vary significantly. Inflammatory reactions that may occur during pregnancy are also related to these changes, and therefore we have addressed this issue and believed that this condition may alter the expression of placental transporters. The aim of this work was to investigate the changes in the expression of membrane transporters using placental cells on BeWo cell lines and placental villous explants that were stimulated by pro-inflammatory mediators. The change in the expression of individual ATP-binding cassettes,...

Rationale: Inadequate monitoring of neuromuscular blockade (NMB) may result in worse patient outcomes, therefore NMB monitor availability is a minimum requirement for perioperative care according to the South African Society of Anaesthesiologists’ (SASA) 2018 Practice Guidelines. The authors performed an audit of peripheral nerve stimulators (PNS) functionality and availability at their institution. In the researcher’s experience the peripheral nerve stimulators (PNS) in use at his institution are not always easily available and some units malfunction at times. There are also not many units that can give a graphical display of a train of four ratio. This observation spurred the idea to do an audit on neuromuscular monitoring at this institution, by focusing on the availability and functionality of peripheral nerve stimulators. Methods: After ethics approval was obtained, an audit was performed. In order to assess function, the PNS were attached to an electrical circuit with a skin equivalent resistance. The resultant current impulses generated using Train-of-Four (TOF) mode and Double Burst Stimulation modes (DBS) were recorded with a voltage scope meter and visually assessed that the TOF was present and appeared equal. PNS availability was assessed in theatre and recovery areas against the SASA guideline standard of nerve stimulator availability. Results: Of the 65 PNS units assessed, 39 units were deemed to be dysfunctional and 26 units fully functional. The most frequent fault found (30 units) related to faulty or absent PNS electrode cables. Eight functional PNS units with TOF ratio display capability were found. The working PNS showed good inter-device peak voltage measurement correlation. Of the 59 areas identified where PNS should be easily available, only 37 areas met the PNS availability criteria suggested in the SASA guidelines. Discussion: This audit revealed that overall there were not enough functional PNS available at the institution, when measured against the SASA standard. The clinical significance of these findings would vary depending on the actual usage rate of NMBs in the area concerned. The logistics of tracking aPNS unit’slocationalso turnsoutto be paramountinsituationswherenerve stimulators have to be shared between areas. From a technical point of view, the working PNS were found to be very consistent in their delivered voltage bursts. Future use of the first generation PNS (without TOF ratio display) will continue to decline, because of their inability to monitor neuromuscular function bymodern standards, and the poor availability ofreplacement parts for models no longer manufactured. The cost and availability of repairs and cable replacementsshould be factored into the decision when acquiring more PNS units. Conclusion: This audit highlighted the need for more new generation PNS with TOF-ratiodisplay- ability to align the institution with the recommendations from SASA standards and the anaesthetic literature. It also highlighted the accuracy and consistency of delivered current bursts by the working PNS devices.

Skeletal muscle has been used for biomechanical assist in experimental and clinical studies. Central to the success of these procedures is the generation of sufficient muscle force for the lifetime of the subject. Burst (tetanic) stimulation results in summation of individual twitches and generates higher power output. However, the superiority of paraneural versus intramuscular as well as proximal versus middle and distal intramuscular stimulations remains unclear. Electrophysiological mapping and mechanical performance of seven canine latissimus dorsi muscles were analyzed. The mechanism of higher tension generation produced by: (1) increased temporal summation; (2) greater motor units activated; or (3) result of both were determined. The parameters primarily dependent on the number of activated motor units are significantly greater following paraneural and proximal intramuscular stimulations. The parameters mainly related to temporal summation are not different between various electrode configurations. For intramuscular stimulation, it is the location of interelectrode field rather than the location of the cathode perse that determines the mechanical performance of the skeletal muscle. Furthermore, tension development of skeletal muscle is primary nerve activation rather than direct muscle stimulation. The higher tension generation that resulted from different electrode configurations is produced by activating a higher number of muscle fibers through the neuromuscular junctions.

Neuromodulatory systems, such as the locus coeruleus (LC) - norepinephrine (NE) system, are integral in the modulation of behavioral state, which in turn exerts a heavy influence on sensory processing, perception, and behavior. LC neurons project diffusely through the forebrain as the sole source of NE. LC tonic firing rate has been shown to correlate with arousal level and behavioral performance. As the LC-NE system innervates sensory pathways and NE has been shown to affect neuronal response, the LC-NE system could potentially allow for state-dependent modulation of sensory processing. However, the precise link between LC activation and sensory processing in the various stages of the sensory pathway that underly perception remained elusive. It is well established that thalamic relay nuclei play an essential role in gating the flow of sensory information to the neocortex, serving to establish cortical representation of sensory environment. Thalamocortical information transmission has been proposed to be strongly modulated by the dynamic interplay between the thalamic relay nuclei and the thalamic reticular nucleus (TRN). Neurons in the early stages of sensory pathways selectively respond to specific features of sensory stimuli. In the rodent vibrissa pathway, thalamocortical neurons in the ventral posteromedial nucleus (VPm) encode kinetic features of whisker movement, allowing stimuli to be encoded by distinctive, temporally precise firing patterns. Therefore, understanding feature selectivity is crucial to understanding sensory processing and perception. However, whether LC activation modulates this feature selectivity, and if it does, the mechanisms through which this modulation occurs, remained largely unknown. This work investigates LC modulation of thalamic feature selectivity through reverse correlation analysis of single-unit recordings from different stages of the rat vibrissa pathway. LC activation increased feature selectivity, drastically improving thalamic information transmission. This improvement was dependent on both local activation of α-adrenergic receptors and modulation of T-type calcium channels in the thalamus and was not due to LC modulation of trigeminothalamic feedforward or corticothalamic feedback inputs. LC activation reduced thalamic bursting, but this change in thalamic firing mode was not the primary cause of the improved information transmission as tonic spikes with LC stimulation carried three-times the information than tonic spikes without LC stimulation. Modelling confirmed NE regulation of intrathalamic circuit dynamics led to the improved information transmission as LC-NE modulation of either relay or reticular nucleus alone cannot account for the improvement. These results suggest a new sub-dimension within the tonic mode in which brain state can optimize thalamic sensory processing through modulation of intrathalamic circuit dynamics. Subsequent computational work was then performed to determine exactly how the encoding of sensory information by thalamic relay neurons was altered to allow for an increase in both information transmission efficiency and rate. The results show that LC-NE induced improvements in feature selectivity are not simply due to an increased signal-to-noise ratio, a shift from bursting to tonic firing, or improvements in reliability or precision. Rather, LC-NE-induced modulation of intrathalamic dynamics changed the temporal response structure thalamic neurons used to encode the same stimuli to a new structure that increased the information carried by both tonic and burst spikes. The shift in events times favors optimal encoding, as more events occur at ideal positions, i.e. when the stimulus most closely matches the neuron’s feature selectivity. Further, this work analyzed the ability to reconstruct the original stimulus using the evoked spike trains of multiple neurons and their recovered feature selectivity from an ideal observer point-of-view. The results showed that LC-activation improved the accuracy of this reconstruction, indicating it may improve the accuracy of perception of whisker stimuli. Finally, to make this work translatable, the use of vagus nerve stimulation (VNS) was investigated as a potential method for minimally invasive enhancement of thalamic sensory processing. The vagus nerve, which runs through the side of the neck, has long been known to have profound effects on brain-state and VNS has been shown to evoke LC firing. This work elucidates the previously uninvestigated short-term effects of VNS on thalamic sensory processing. Similar to direct LC stimulation, VNS enhanced the feature selectivity of thalamic neurons, resulting in a significant increase in the efficiency and rate of stimulus-related information conveyed by thalamic spikes. VNS-induced improvement in thalamic sensory processing also coincided with a decrease in thalamic burst firing, suggesting the same underlying mechanism as the improvements induced with direct LC stimulation.

Every year 1.4 million people will suffer from a traumatic brain injury (TBI). The Centers for Disease Control (CDC) estimates that there are over 5.3 million TBI survivors living in the United States, or about two percent of the population, living with long-term effects or in need of lifelong help. Estimations have been made that with both the direct and indirect costs of medical bills and productivity loss in the United States the total cost for TBI was 60 billion dollars in 2000. Sensory stimulation consists of visual, tactile, auditory, gustatory, and-olfactory stimuli that attempt to increase the levels of conscio-µsness in TBI patients by enhancing synaptic reinnervation in the brain. Sensory stimulation has been around since the 1980's and has been found to be beneficial for TBI patients, however, no guidelines have been created for nurses and other health care providers to perform this program. By making guidelines for nurses and other health care providers that outline the proper procedure of this treatment, the cost for care of TBI patients will decrease, therefore positively impacting the health care system.