Combination Of Electrical Stimulation Research Articles

Effects of Spinal Cord Electrical Stimulation in Patients with Vertebrospinal Pathology

Until now, no scientific neurophysiologic methods of diagnostics and treatment of vertebrospinal pathologies were developed. Previous study showed that electrical stimulation of lumbar segments of the spinal cord in animals with complete spinal cord transection induced a well-coordinated weight-bearing locomotion. The present comparative study of motor activity triggered by electrical epidural stimulation of one or two segments of the spinal cord in spinal patients showed that stimulation of lumbar (L2-L4) or sacral (S2) segments facilitated generation of motor patterns of muscle activity. Combination of electrical stimulation with locomotor training resulted in the appearance of stepping patterns characteristic of normal walking and tonic activity of the muscles needed for body balance maintenance.

A Microfabricated Platform to Measure and Manipulate the Mechanics of Engineered Cardiac Microtissues

Engineered myocardial tissues can be used to elucidate fundamental features of myocardial biology, develop organotypic in vitro model systems, and as engineered tissue constructs for replacing damaged heart tissue in vivo. However, a key limitation is an inability to test the wide range of parameters (cell source, mechanical, soluble and electrical stimuli) that might impact the engineered tissue in a high-throughput manner and in an environment that mimics native heart tissue. Here we used microelectromechanical systems technology to generate arrays of cardiac microtissues (CMTs) embedded within three-dimensional micropatterned matrices. Microcantilevers simultaneously constrain CMT contraction and report forces generated by the CMTs in real time. We demonstrate the ability to routinely produce ~200 CMTs per million cardiac cells (<1 neonatal rat heart) whose spontaneous contraction frequency, duration, and forces can be tracked. Independently varying the mechanical stiffness of the cantilevers and collagen matrix revealed that both the dynamic force of cardiac contraction as well as the basal static tension within the CMT increased with boundary or matrix rigidity. Cell alignment is, however, reduced within a stiff collagen matrix; therefore, despite producing higher force, CMTs constructed from higher density collagen have a lower cross-sectional stress than those constructed from lower density collagen. We also study the effect of electrical stimulation on cell alignment and force generation within CMTs and we show that the combination of electrical stimulation and auxotonic load strongly improves both the structure and the function of the CMTs. Finally, we demonstrate the suitability of our technique for high-throughput monitoring of drug-induced changes in spontaneous frequency or contractility in CMTs as well as high-speed imaging of calcium dynamics using fluorescent dyes. Together, these results highlight the potential for this approach to quantitatively demonstrate the impact of physical parameters on the maturation, structure, and function of cardiac tissue and open the possibility to use high-throughput, low volume screening for studies on engineered myocardium.

Influence of Intergeneric/Interspecies Mitochondrial Injection; Parthenogenetic Development of Bovine Oocytes after Injection of Mitochondria Derived from Somatic Cells

Interspecies/intergeneric mitochondrial heteroplasmy can occur in interspecies/intergeneric hybrid embryos or following nuclear transfer. In the present study, intergeneric buffalo (Bubalus bubalis) mitochondria (WB-mt) or interspecies murine (Mus spretus) mitochondria (M-mt) were injected into bovine (Bos taurus) oocytes, and the subsequent embryonic development was characterized. Fibroblast mitochondria (WB-mt or M-mt) were microinjected into in vitro matured bovine oocytes followed by oocyte activation by a combination of electrical stimulation and 6-dimethylaminopurine treatment. After seven days of culture, embryo development was evaluated. The copy number of specific mtDNA populations (introduced and native mtDNA) from heteroplasmic oocytes was estimated using real-time PCR. The results illustrated that oocytes injected with either WB-mt or M-mt can develop to the blastocyst stage (20.6% and 19.6%). Cleavage division rates and development to the morula stage in oocytes injected with WB-mt were lower (76.2% and 45.9%, respectively) in comparison with uninjected oocytes (89.2% and 59.1%, respectively) (P<0.05). However, no differences were found in comparing M-mt injected oocytes and controls (P>0.05). An increase in bovine mtDNA copy number was observed at the expanded blastocyst stage of injected embryos (P<0.01), while the number of injected mtDNA was stable throughout development. This study demonstrates that interspecies/intergeneric mitochondrial injected bovine oocytes have the ability to develop to the blastocyst stage after parthenogenetic activation and that injected mtDNA was neither selectively destroyed nor enhanced through development. Moreover, injected intergeneric mitochondria had a demonstrated influence on bovine parthenogenetic development and mtDNA replication.

Non-invasive neuromuscular electrical stimulation in patients with central nervous system lesions: An educational review

The aim of this educational review is to provide an overview of the clinical application of transcutaneous electrical stimulation of the extremities in patients with upper motor neurone lesions. In general two methods of electrical stimulation can be distinguished: (i) therapeutic electrical stimulation, and (ii) functional electrical stimulation. Therapeutic electrical stimulation improves neuromuscular functional condition by strengthening muscles, increasing motor control, reducing spasticity, decreasing pain and increasing range of motion. Transcutaneous electrical stimulation may be used for neuromuscular electrical stimulation inducing repetitive muscle contraction, electromyography-triggered neuromuscular electrical stimulation, position-triggered electrical stimulation and subsensory or sensory transcutaneous electric stimulation. Functional electrical stimulation provokes muscle contraction and thereby produces a functionally useful movement during stimulation. In patients with spinal cord injuries or stroke, electrical upper limb neuroprostheses are applied to enhance upper limb and hand function, and electrical lower limb neuroprostheses are applied for restoration of standing and walking. For example, a dropped foot stimulator is used to trigger ankle dorsiflexion to restore gait function. A review of the literature and clinical experience of the use of therapeutic electrical stimulation as well as of functional electrical stimulation in combination with botulinum toxin, exercise therapy and/or splinting are presented. Although the evidence is limited we conclude that neuromuscular electrical stimulation in patients with central nervous system lesions can be an effective modality to improve function, and that combination with other treatments has an additive therapeutic effect.

The combined effect of electrical stimulation and resistance isometric contraction on muscle atrophy in rat tibialis anterior muscle

Electrical stimulation has been used to prevent muscle atrophy, but this method is different in many previous studies, appropriate stimulation protocol is still not decided. Although resistance exercise has also been shown to be an effective countermeasure on muscle atrophy, almost previous studies carried out an electrical stimulation without resistance. It was hypothesized that electrical stimulation without resistance is insufficient to contract skeletal muscle forcefully, and the combination of electrical stimulation and forceful resistance contraction is more effective than electrical stimulation without resistance to attenuate muscle atrophy. This study investigated the combined effects of electrical stimulation and resistance isometric contraction on muscle atrophy in the rat tibialis anterior muscle. The animals were divided into control, hindlimb unloading (HU), hindlimb unloading plus electrical stimulation (ES), and hindlimb unloading plus the combination of electrical stimulation and resistance isometric contraction (ES+IC). Electrical stimulation was applied to the tibialis anterior muscle percutaneously for total 240 sec per day. In the ES+IC group, the ankle joint was fixed to produce resistance isometric contraction during electrical stimulation. After 7 days, the cross-sectional areas of each muscle fiber type in the HU group decreased. Those were prevented in the ES+IC group rather than the ES group. The expression of heat shock protein 72 was enhanced in the ES and ES+IC groups. These results indicated that although electrical stimulation is effective to prevent muscle atrophy, the combination of electrical stimulation and isometric contraction have further effect.

Functional electrical stimulation combined with botulinum toxin type A to improve hand function in children with spastic hemiparesis – a pilot study

Children with spastic hemiparesis frequently present with impaired hand function due to paresis, spasticity, and disturbed motor control. The aim of this study was to examine the effectiveness of functional electrical stimulation in combination with botulinum toxin type A in these children. Randomized, controlled, observer-blinded pilot study. Children with impaired hand function. Either a combined treatment group (functional electrical stimulation and botulinum toxin type A) or a botulinum toxin type A group alone. Botulinum toxin type A was injected into arm muscles according to the patient's clinical requirements. Functional electrical stimulation of the wrist and finger extensor muscles was started after five to six days. Patients were given a stimulation device and asked to use it at home twice daily for 15 min, for a total period of three months. Active and passive range of motion, muscle tone, muscle strength, and functional tests for children. Six children aged between 7 and 17 years with spastic hemiparesis were enrolled. In both groups, active and passive range of motion, muscle tone, and muscle strength improved after three and six months compared to baseline data. The functional score was improved only in the group that received combined treatment. Combined treatment with functional electrical stimulation and botulinum toxin type A is a promising treatment option to improve upper limb function in children with spastic hemiparesis.

The Combined Effect of Electrical Stimulation and High‐Load Isometric Contraction on Protein Degradation Pathways in Muscle Atrophy Induced by Hindlimb Unloading

High-load isometric exercise is considered an effective countermeasure against muscle atrophy, but therapeutic electrical stimulation for muscle atrophy is often performed without loading. In the present study, we investigated the combined effectiveness of electrical stimulation and high-load isometric contraction in preventing muscle atrophy induced by hindlimb unloading. Electrical stimulation without loading resulted in slight attenuation of muscle atrophy. Moreover, combining electrical stimulation with high-load isometric contraction enhanced this effect. In electrical stimulation without loading, inhibition of the overexpression of calpain 1, calpain 2, and MuRF-1 mRNA was confirmed. On the other hand, in electrical stimulation with high-load isometric contraction, inhibition of the overexpression of cathepsin L and atrogin-1 mRNA in addition to calpain 1, calpain 2, and MuRF-1 mRNA was confirmed. These findings suggest that the combination of electrical stimulation and high-load isometric contraction is effective as a countermeasure against muscle atrophy.

The effect of electrical stimulation in combination with Bobath techniques in the prevention of shoulder subluxation in acute stroke patients

Objective: To examine the efficiency of electrical stimulation in combination with Bobath techniques in the prevention of inferior and anterior shoulder subluxation in acute stroke patients. Design: A prospective randomized controlled trial. Setting: Intensive care unit and inpatient clinics of neurology in a university hospital. Subjects: Forty-eight patients with acute stroke, divided equally into control and study groups. Intervention: Subjects in both groups were treated in accordance with the Bobath concept during the early hospitalization period. In addition to Bobath techniques, electrical stimulation was also applied to the supraspinatus muscle, mid and posterior portions of the deltoid muscle of patients in the study group. Main measures: Two radiological methods were used to measure the horizontal, vertical and total asymmetry and vertical distance values of the shoulder joint. Motor functions of the arm were evaluated with the Motor Assessment Scale. Results: The hospitalization period was 12.62 ± 2.24 days for the control group and 11.66 ± 1.88 days for the study group. Shoulder subluxation occurred in 9 (37.5%) subjects in the control group, whereas it was not observed in the study group. All shoulder joint displacement values were higher in the control group than in the study group (horizontal asymmetry P = 0.0001, vertical asymmetry P = 0.0001, total asymmetry P = 0.0001, vertical range P = 0.002). Conclusion: Application of electrical stimulation combined with the Bobath approach proved to be efficient in preventing inferior and anterior shoulder subluxation in the acute stages of stroke.

Intraneural Injection of Local Anesthetics during Ultrasound-guided Peripheral Nerve Block May Lead to Nerve Injury

Clinique du Parc saint Lazare, Beauvais, France. balnasser@wanadoo.frI read with interest the article by Bigeleisen.1In this article, the author presented a prospective study of ultrasound-guided axillary blocks and determined the incidence of nerve puncture, intraneural injection of local anesthetics, and transient or permanent nerve injuries. After reading this well-written article it occurred to me that there are some points that may add to discussion. Damage may be caused to peripheral nerves after regional anesthesia techniques by mechanical, chemical, or ischemic injuries, which may occur alone or in combination.2Iohom et al. 2reported that intraneural injection of ropivacaine in rat sciatic nerve, in a concentration routinely used in clinical practice, caused no deleterious effect on motor function. Hadzic et al. 3reported varying degrees of damage to the neural architecture after high-pressure injection of local anesthetic in dog sciatic nerve. This damage ranged from mechanical disruption and delamination to fragmentation of the myelin sheath and marked cellular infiltration. They also reported severe and persistent motor deficits.3Since the introduction of ultrasound-guided peripheral nerve blocks at my institution, I frequently observe nerve puncture during this procedure. In my experience, the combination of electrical stimulation does not result always in motor response even if the needle tip is positioned intraneurally. In the same condition, I also sometimes observe no pain on intraneural injection. The advantage of ultrasound-guided nerve blocks in my practice is that I can watch the needle’s advancement in real time. Accordingly, in case I suspect nerve puncture, I slightly withdraw the needle and avoid intraneural injection to increase safety. In this study, the author excluded 22 patients from the study because of preoperative abnormalities in their motor and sensory examination. In daily practice, patients may present some degree of neurologic abnormalities before surgery. They may also be at high risk of nerve damage. Furthermore, intraneural injection in these patients may lead to an aggravating condition of their preexisting neuropathy. There are multiple causes and a combination of factors that may lead nerve injury after regional anesthesia techniques.4However, peripheral nerves have a dual blood supply of intrinsic exchange vessels in the endoneurium and an extrinsic plexus of supply vessels in the epineurial space that cross the perineurium to anastomose with intrinsic circulation.2Accordingly, nerve ischemia due to intraneural compression (local anesthetic volume or edema) and/or perineural compression (local anesthetic volume) may cause permanent or transient nerve damage.4Moreover, high-pressure intrafascicular or endoneural injection may also cause neural damage.3Consequently, the combination of ischemia, high-pressure intrafascicular or endoneural injection and local anesthetic toxicity could be deleterious to peripheral nerves.3,4According to my experience, it is difficult to tell from the ultrasound image after apparent intraneural placement of the needle tip, whether the needle is positioned perineurially, epineurially, or endoneurially. The injection of the local anesthetic, even in a small quantity, in one of these positions may not lead to the same outcome. Furthermore, endoneural injection could result in nerve damage by promoting ischemic changes.2For this reason, I believe that avoidance of intraneural placement of the needle tip should be a major concern during ultrasound-guided peripheral nerve blocks. Moreover, performing a peripheral nerve block in real time and under direct vision gives us the possibility to correct the needle position, avoid intraneural injections, and avoid nerve injury.In conclusion, although this study and other reports1,2suggested that nerve puncture and intraneural injection of low to moderate volumes of local anesthetic do not inevitably lead to neurologic injury, the role of ultrasound-guided peripheral nerve blocks is to increase safety. Even if we hypothesize that intraneural injections do not lead to neurologic damage, they present no advantage over perineural injections in rapidity of installation or in success rate after ultrasound-guided techniques. Finally, practitioners who have already experienced neurologic problems after regional anesthesia techniques always remember the difficulties encountered during the long way of patient care.Clinique du Parc saint Lazare, Beauvais, France. balnasser@wanadoo.fr

Effects of botulinum toxin guided by electric stimulation on spasticity in ankle plantar flexor of children with cerebral palsy: a randomized trial

To compare the effects of botulinum toxin A (BTX-A) injection guided by electric stimulation combined with physiotherapy, with physiotherapy only on the spasticity of the ankle plantar flexor in children with cerebral palsy (CP). After signing the informed consent, 43 children with CP, aged 52.4 +/- 13.2 months (35 to 82 months), were randomly assigned into 2 groups, (1) BTX-A group (n = 23) treated with BTX-A injection guided by electric stimulation and (2) physiotherapy alone group (n = 20). Children in BTX-A group received injection of HengLi BTX-A in the ankle plantar flexors. A maximum dose of 12 units of BTX-A per kilogram body weight and maximumly 10 units of BTX-A per site were administered. Localization technique was the use of electrical stimulation guidance. Physiotherapy and ankle-foot orthosis were applied to children at 72 hours after injection in BTX-A group and at the time of being recruited into physiotherapy group. Ten days after entering into the study, the program was applied by the parents. Demographic data, including age, gender, number of the spastic lower limbs, affected side (left or right) were recorded. Clinical assessments included the range of passive movement (PROM) measured by goniometer while children maintained the knee extended, modified Ashworth scale (MAS), composite spasticity scale (CSS), D and E dimensions of the Gross Motor Function Measure (GMFM), and walking velocity (WV) was determined before treatment and at 2 weeks, 1, 2, and 3 months after treatment. No statistically significant differences were found in age, gender, number of the spastic lower limbs, affected side, as well as clinical assessments (PROM, MAS, CSS, GMFM and WV) before treatment between the 2 groups (P > 0.05). All the children showed a reduction of spasticity (PROM, MAS and CSS) after 2 weeks, 1, 2, and 3 months of treatment (P < 0.05). When compared with the baseline findings, the improvement of standing and walking (GMFM), walking velocity were statistically significant after 2 weeks, 1, 2, and 3 months of treatment (P < 0.05). Furthermore, the differences of PROM, MAS and CSS between the 2 groups at 2 weeks, 1, 2, and 3 months examination were also statistically significant (after 3 months of treatment: t(PROM) = 6.48, t(MAS) = 9.74, t(CSS) = 9.59; P < 0.05). The difference in GMFM between the 2 groups was statistically significant (t(1M) = 2.20, t(2M) = 3.26, t(3M) = 4.13; P < 0.05) at 1, 2, and 3 months after treatment. The difference of WV between the 2 groups was statistically significant (t(2M) = 2.12, t(3M) = 2.57; P < 0.05) at 2 and 3 months after treatment. BTX-A injection guided by electrical stimulation in combination with physiotherapy was more effective than physiotherapy alone in terms of reducing spasticity and improving functional performance in standing, walking, walking pattern and velocity on spasticity in ankle plantar flexors of ambulant children with CP.

Neuroprosthetics of the upper extremity--clinical application in spinal cord injury and future perspectives.

Within the last couple of years, partial restoration of lost motor functions in a larger number of spinal cord injured patients has become possible by the introduction of neuroprostheses into the clinical environment. The Freehand system in particular is the first implantable neuroprosthesis from which a certain group of tetraplegic patients with stable shoulder function, but missing or weak grasp and hold function of the hand do benefit. The system is based on the combination of electrical stimulation and operative tendon transfers and thus represents a multicomponent concept for long-term restoration of the grasp function. The crucial prerequisites for successful use of an implantable neuroprosthesis are the right indication, careful preoperative muscle stimulation, differentiated planning of the surgery and functional training adopted to the individual residual functions. After successful completion of an extensive rehabilitation program, patients are able to use the system for activities of daily living without the need for special additional aids, which enhances their quality of life and independency. In order to extend the group of potential users of neuroprostheses in the future, new technological developments will have to take into account that nowadays the majority of spinal cord injured patients suffer from an incomplete lesion of the spinal cord. For these particular patients who still possess residual functions, modular, "naturally" controllable systems for supporting these functions are needed rather than complex systems to substitute them.

EFFECTS OF VITAMIN E AND ELECTRICAL STIMULATION ON THE DENERVATEDRAT GASTROCNEMIUS MUSCLE MALONDIALDEHYDE AND GLUTATHIONE LEVELS

Effects of vitamin E treatment and local electrical stimulation on progression of atrophy in the denervated rat gastrocnemius muscle were studied. Denervation was performed by right leg sciatic nerve axotomy. Electrical stimulation (3-10 mA ms–1, 10 min per day for 7 days) was applied to the right gastrocnemius muscle starting from day 1 of denervation. The muscle samples were assayed for malondialdehyde (MDA) and glutathione levels, as well as the histological appearance after 8 days of denervation. MDA levels were markedly increased following denervation. However, electrical stimulation, vitamin E treatment (30 mg kg–1, i.m., everyday for 7 days), and combination of electrical stimulation and vitamin E treatment markedly reduced MDA levels. Glutathione levels were significantly decreased in the denervation group. Electrical stimulation, vitamin E treatment, and electrical stimulation plus vitamin E treatment prevented these reductions in glutathione levels. In the vitamin E treatment group, glutathione levels were markedly higher than in the control group. These results indicate that electrical stimulation and vitamin E treatment alone, or in combination, were able to prevent the effects of denervation on muscle atrophy

Determination of optimal conditions for parthenogenetic activation and subsequent development of rat oocytes in vitro.

The present study was undertaken to determine optimal conditions for parthenogenetic activation and subsequent development of rat oocytes. Oocytes from immature Wistar-Imamichi (WI) and Sprague Dawley (SD) rats were activated by electrical stimulation in combination with 6-dimethylaminopurine (6-DMAP) to assess whether different rat strains display different responses to activation treatment. Since the cleavage rates of activated oocytes were significantly higher in WI than SD strain rats, WI rats were used for the subsequent experiments to determine the effects of post-hCG time, culture duration, different activation protocols (electrical stimulation with 6-DMAP or ionomycin with 6-DMAP) and osmolarity of the activation medium on the activation and subsequent development of WI rat oocytes. For oocytes activated by electrical stimulation combined with 6-DMAP, the percentages of oocytes that were activated and that developed to blastocysts were higher when oocytes were collected at 18-20 h than at any other time points after hCG injection (16, 22-24 h). Culturing for 2-6 h before activation treatment markedly decreased the percentage of activated oocytes that developed to beyond the four-cell stage. There were no differences in the percentages of oocytes with pronuclear formation and subsequent development to the two-cell and blastocyst stages between oocytes that were activated by electrical stimulation or ionomycin, both followed by 6-DMAP treatment. Activation of oocytes by ionomycin and 6-DMAP, both in low osmolarity media (246 mOsM), markedly increased the cleavage rates and percentages of high quality blastocysts (71%). The optimal conditions determined in the present study with simplified activation protocols and high efficiency of activation and subsequent development of WI rat oocytes will be helpful for further research involving nuclear transfer in the rat.

Enhancement of spinal fusion using calcium phosphate–based graft substitutes

Enhancement of spinal fusion using calcium phosphate–based graft substitutes

Relative Influence of Low-voltage Electrical Stimulation, Chilling Rate and Ageing Time on Tenderness of M. longissimus dorsi of Norwegian Cattle

The effects of gender, low-voltage electrical stimulation (LV-ES; 90 V, 15 Hz, 20 s), chilling rate and ageing time on the tenderness of hot-boned M. longissimus dorsi were studied on 47 Norwegian Cattle carcasses. There were 24 female cattle (14?96 months) and 23 bulls (15?24 months) in the sample set, of which 12 from each gender were exposed to electrical stimulation. One part of each loin was chilled at 15°C for the first 24 h post mortem and thereafter aged at 4°C for 6 more days. The other part of the loin was chilled directly to 4°C and aged until 7 days post mortem. Ageing time was the most influential factor for Warner-Bratzler shear force, but chilling rate was also highly significant. Neither gender nor LV-ES had significant effects on tenderness in this study. The combination of electrical stimulation and rapid chilling did not improve tenderness as much as moderate chilling alone. This experiment showed that chilling rate during rigor and time of ageing were the two most important factors for the tenderness of beef M. longissimus dorsi.

Neuromuscular Electrical Stimulation After Anterior Cruciate Ligament Surgery

This randomized, double blind, controlled trial was designed to determine the effectiveness of neuromuscular electrical stimulation of the knee extensor and flexor muscles in the prevention of muscular weakening after anterior cruciate ligament surgery. Neuromuscular electrical stimulation treatment was given in addition to an early exercise therapy regimen and compared with an early exercise therapy regimen alone. Forty-nine patients after anterior cruciate ligament surgery were assigned randomly either to a neuromuscular electrical stimulation and exercise group, a transcutaneous electrical nerve stimulation as analgesic and exercise group, or an exercise alone group as control. All groups received a standard regimen of rehabilitation after anterior cruciate ligament surgery. The neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation group additionally received electrical stimulation during the first 6 weeks after surgery. Patients were measured for isometric and isokinetic torque in the knee extensor and flexor muscles after 6, 12, and 52 weeks. No statistical difference among groups was observed. It is concluded that neuromuscular electrical stimulation in combination with an early exercise therapy regimen is not significantly more effective in reducing weakening than an early exercise therapy regimen alone after anterior cruciate ligament surgery.

Electrical Stimulation Prolongs the Survival Days of Leukemic Mice Treated With Methotrexate

To investigate effects of electrical stimulation on survival days of leukemic mice treated with methotrexate (MTX), L1210-bearing mice were treated by MTX and calcium folinate (leucovorin®) rescue therapy (MTX: 400 mg/kg, followed by leucovorin at the dose of 7.5 mg/kg at 8, 15 and 24 hr after MTX) under electrical stimulation (foot shock: shock amplitude, 0.4 mA; voltage, 60–100 V/cm; shock duration, 5 sec; frequency, 0.5 Hz) of various lengths. The survival days were significantly prolonged by 6-hr electrical stimulation in combination with MTX, while plasma MTX concentrations and pharmacokinetic parameters such as the area under the curve (AUC0–12hr) and clearance (CL) were not significantly altered. Psychological stress did not alter the efficacy of MTX in the communication box paradigm. Amplified efficacy of MTX was shown in a length-dependent manner when electrical stimulation of various lengths were applied to L1210-bearing mice.

Effect of electrical stimulation in combination with calcium chloride or sodium chloride treatments at constant ionic strength on moisture binding and textural quality of early-harvested breast fillets

The objective of this study was to assess the effects of a CaCl2 or NaCl treatment combined with electrical stimulation (ES) on textural and moisture binding of early-harvested chicken breast fillets. During exsanguination, half the birds were subjected to ES, and then all carcasses were aged for 30, 60, 90, or 120 min before excising both Pectoralis major muscles. Half the muscles were chilled with a NaCl solution and half with a CaCl2 solution. Effects of ES and chill medium composition on meat pH, moisture absorption, cooking loss, and shear value of the fillets were assessed. The ES reduced meat pH for the NaCl-treated muscles, but had no effect on those treated with CaCl2 of on moisture absorbed during chilling. Cooking loss was greater for the CaCl2-treated than NaCl-treated muscles and for muscles from stimulated birds that were excised more than 30 min post-mortem. Shear values were unaffected by chilling medium composition. However, even though shear values for both ES and unstimulated birds declined as aging time increased, the rate of decline was greater, and ultimate shear value lower, for muscles from ES birds. Results indicate that, although ES might offer some advantage in improving the tenderness of early-harvested breast fillets, combining ES with CaCl2 treatment offers no real advantage. Moreover, reductions in moisture binding properties by these technologies might limit applicability in some commercial environments.

Electrical stimulation of the substantia nigra reticulata: detection of neuronal extracellular GABA in the ventromedial thalamus and its regulatory mechanism using microdialysis in awake rats.

A combination of electrical stimulation and microdialysis was used to study the nigrothalamic gamma aminobutyric acid (GABA)ergic system and its regulatory mechanisms in awake rats. Extracellular GABA levels in the ventromedial nucleus of the thalamus were detected in 3-min fractions collected before, during and after a 10-min stimulation period of the substantia nigra reticulata. Electrical stimulation of the substantia nigra reticulata increased the GABA levels to 155% of basal values in the ventromedial thalamus only during the first 3-min interval upon stimulation. The increase in GABA levels was tetrodotoxin-dependent, implicating an exocytotic origin. The basal levels of extracellular GABA in the ventromedial thalamus were of nonexocytotic origin. To study the mechanism underlying the fast compensatory response in neuronal GABA release after nigral stimulation, local infusions into the ventromedial thalamus of reuptake inhibitors and GABA antagonists were performed and the effect of nigral stimulation was examined under the various applications. Local infusion of the reuptake inhibitors nipecotic acid (500 microM) and SKF 89976-A (20 and 50 microM) increased extracellular GABA levels to 350%, 180% and 600%, respectively, of basal values in the ventromedial thalamus tetrodotoxin-independently. Under these conditions, the increase in extracellular GABA was absent (nipecotic acid) or suppressed (20% of basal values; SKF 89976-A for both doses), leaving it unsolved whether or not the uptake system was responsible for the fast compensation in neuronal GABA after stimulation. The GABA-A antagonist bicucilline (50 microM) was ineffective when infused locally in the ventromedial thalamus, but prolonged the increase in neuronal GABA release after nigral stimulation; the GABA levels were increased during two 3-min samples to approximately 165%, indicating a functional role for GABA-A receptors in regulating the release of GABA from nigrothalamic GABAergic neurons. The GABA-B receptor antagonist CGP 35348 (50 microM) did not affect GABA levels when infused locally in the ventromedial thalamus and neither affected the response in neuronal GABA after stimulation. This finding does not support a role for GABA-B receptors in controlling the release from the nigrothalamic neurons.

Correlation between patterns of horizontal connectivity and the extend of short-term representational plasticity in rat motor cortex.

Plasticity of representational maps in adult cerebral cortex has been documented in both sensory and motor cortex, but the anatomical basis for cortical plasticity remains poorly understood. To investigate horizontal connectivity in primary motor cortex (M1) as a putative anatomical substrate for short-term, functional plasticity of adult motor cortical representations, a combination of electrical stimulation and biocytin labeling was used to examine pre-existing patterns of intrinsic connections in adult rat M1 in relationship to the pattern of reorganization of the motor movement may induced by transection of the contralateral facial nerve. Two hours after nerve cut, small, circumscribed regions of the forelimb representation expanded medially into territory previously devoted to the vibrissae representation. Outside of this novel, expanded forelimb region, no forelimb movement could be evoked from the former vibrissae representation at any time over the period of hours tested, thus representing silent cortex. Injections placed into vibrissae cortex representing the newly expanded forelimb representation gave rise to labeled axons and dense terminal fiber labeling which crossed the forelimb/vibrissae border and extended up to 1.2 mm within the low-threshold forelimb representation. In contrast, injections placed into silent vibrissae cortex gave rise to labeled axons and terminal boutons which remained mostly restricted to the original vibrissae representation, with only sparse projections that crossed into the low-threshold forelimb representation. Thus, these results suggest that the extent of short-term, functional reorganization of M1 induced within the first several hours following peripheral nerve cut is mediated, and constrained, by an anatomical framework of pre-existing, horizontal projections which traverse representation borders.