Muscle Flexor Digitorum Research Articles

Increased CCN2, substance P and tissue fibrosis are associated with sensorimotor declines in a rat model of repetitive overuse injury.

Key clinical features of cumulative trauma disorders include pain, muscle weakness, and tissue fibrosis, although the etiology is still under investigation. Here, we characterized the temporal pattern of altered sensorimotor behaviors and inflammatory and fibrogenic processes occurring in forearm muscles and serum of young adult, female rats performing an operant, high repetition high force (HRHF) reaching and grasping task for 6, 12, or 18weeks. Palmar mechanical sensitivity, cold temperature avoidance and spontaneous behavioral changes increased, while grip strength declined, in 18-week HRHF rats, compared to controls. Flexor digitorum muscles had increased MCP-1 levels after training and increased TNFalpha in 6-week HRHF rats. Serum had increased IL-1beta, IL-10 and IP-10 after training. Yet both muscle and serum inflammation resolved by week 18. In contrast, IFNγ increased at week 18 in both muscle and serum. Given the anti-fibrotic role of IFNγ, and to identify a mechanism for the continued grip strength losses and behavioral sensitivities, we evaluated the fibrogenic proteins CCN2, collagen type I and TGFB1, as well as the nociceptive/fibrogenic peptide substance P. Each increased in and around flexor digitorum muscles and extracellular matrix in the mid-forearm, and in nerves of the forepaw at 18weeks. CCN2 was also increased in serum at week 18. At a time when inflammation had subsided, increases in fibrogenic proteins correlated with sensorimotor declines. Thus, muscle and nerve fibrosis may be critical components of chronic work-related musculoskeletal disorders. CCN2 and substance P may serve as potential targets for therapeutic intervention, and CCN2 as a serum biomarker of fibrosis progression.

Monopolar electromyographic signals recorded by a current amplifier in air and under water without insulation

It was recently proposed that one could use signal current instead of voltage to collect surface electromyography (EMG). With EMG-current, the electrodes remain at the ground potential, thereby eliminating lateral currents. The purpose of this study was to determine whether EMG-currents can be recorded in Tap and Salt water, as well as in air, without electrically shielding the electrodes. It was hypothesized that signals would display consistent information between experimental conditions regarding muscle responses to changes in contraction effort. EMG-currents were recorded from the flexor digitorum muscles as participant’s squeezed a pre-inflated blood pressure cuff bladder in each experimental condition at standardized efforts. EMG-current measurements performed underwater showed no loss of signal amplitude when compared to measurements made in air, although some differences in amplitude and spectral components were observed between conditions. However, signal amplitudes and frequencies displayed consistent behavior across contraction effort levels, irrespective of the experimental condition. This new method demonstrates that information regarding muscle activity is comparable between wet and dry conditions when using EMG-current. Considering the difficulties imposed by the need to waterproof traditional bipolar EMG electrodes when underwater, this new methodology is tremendously promising for assessments of muscular function in aquatic environments.

Muscle intrusion as a potential cause of carpal tunnel syndrome

The aim of this study was to determine whether there is an association between flexor digitorum and lumbrical muscle intrusion into the carpal tunnel and carpal tunnel syndrome (CTS). Five hundred thirteen manual laborers (1026 wrists) were evaluated with ultrasound to determine whether those with CTS had more muscle intrusion into the carpal tunnel than those without CTS. One hundred ninety of the participants without CTS at baseline (363 wrists) were followed over 1 year to determine whether muscle intrusion at baseline predicted the development of CTS. Participants with CTS had more muscle within the carpal tunnel with the wrist in the neutral (P=0.026) and flexed (P=0.018) positions than those without CTS. Baseline muscle intrusion did not predict development of CTS at 1 year. Muscle intrusion into the carpal tunnel is associated with CTS, but muscle intrusion alone does not predict the development of CTS over the course of a year.

The interaction of force and repetition on musculoskeletal and neural tissue responses and sensorimotor behavior in a rat model of work-related musculoskeletal disorders

BackgroundWe examined the relationship of musculoskeletal risk factors underlying force and repetition on tissue responses in an operant rat model of repetitive reaching and pulling, and if force x repetition interactions were present, indicative of a fatigue failure process. We examined exposure-dependent changes in biochemical, morphological and sensorimotor responses occurring with repeated performance of a handle-pulling task for 12 weeks at one of four repetition and force levels: 1) low repetition with low force, 2) high repetition with low force, 3) low repetition with high force, and 4) high repetition with high force (HRHF).MethodsRats underwent initial training for 4–6 weeks, and then performed one of the tasks for 12 weeks, 2 hours/day, 3 days/week. Reflexive grip strength and sensitivity to touch were assayed as functional outcomes. Flexor digitorum muscles and tendons, forelimb bones, and serum were assayed using ELISA for indicators of inflammation, tissue stress and repair, and bone turnover. Histomorphometry was used to assay macrophage infiltration of tissues, spinal cord substance P changes, and tissue adaptative or degradative changes. MicroCT was used to assay bones for changes in bone quality.ResultsSeveral force x repetition interactions were observed for: muscle IL-1alpha and bone IL-1beta; serum TNFalpha, IL-1alpha, and IL-1beta; muscle HSP72, a tissue stress and repair protein; histomorphological evidence of tendon and cartilage degradation; serum biomarkers of bone degradation (CTXI) and bone formation (osteocalcin); and morphological evidence of bone adaptation versus resorption. In most cases, performance of the HRHF task induced the greatest tissue degenerative changes, while performance of moderate level tasks induced bone adaptation and a suggestion of muscle adaptation. Both high force tasks induced median nerve macrophage infiltration, spinal cord sensitization (increased substance P), grip strength declines and forepaw mechanical allodynia by task week 12.ConclusionsAlthough not consistent in all tissues, we found several significant interactions between the critical musculoskeletal risk factors of force and repetition, consistent with a fatigue failure process in musculoskeletal tissues. Prolonged performance of HRHF tasks exhibited significantly increased risk for musculoskeletal disorders, while performance of moderate level tasks exhibited adaptation to task demands.

P 80. Corticospinal synchrony might mediate feature extraction in implicit motor learning

Dynamic adaptation and improvements of motor skills are achieved in terms of implicit motor learning. Neuronal and neuromuscular synchronization (coherence) contribute significantly to the accuracy of motor control. However, it remains to be defined whether this also applies for corticospinal network adaptations during the process of implicit motor learning. We aimed to gain insight into the cortical and corticospinal integration of implicit motor learning. We tested 15 healthy subjects using the Serial Reaction Time Task (SRTT): after a random baseline block [Bl] subjects performed four sequential blocks ([Sa] to [Sd]), followed by a random block [Rc], another sequential block [Se] and again one random block [Rd]. We recorded simultaneous 64-channel EEG and surface EMG of the Flexor Digitorum (FD) and Extensor Digitorum (ED) muscles. We analyzed the performance data, power spectral density (PSD) of cortical and muscular activation, as well as event-related cortical time–frequency power spectra and corticospinal time–frequency coherence spectra using the Morlet wavelet algorithm. Time-locked data was analyzed with respect to the button-press and pooled for performance blocks. As expected, subjects showed a significant decrease of reaction times in the sequence blocks [Sc] and [Sd] reflecting implicit motor learning (repeated measures ANOVA revealed significant differences between blocks ( F 7 = 4256, P = 0.001). [Sc] (one-tailed paired t -test, t 11 = 3.102, P = 0.04) and [Sd] (one-tailed paired t -test, t 11 = 2.888, P = 0.03) displayed significantly shorter reaction times compared to [Bl]). Corticomuscular coherence (CMC) time-locked to FD activation increased after the baseline, reached maximal peak amplitude when reaction time decreased in the sequence blocks and was strongest in low and high gamma (30–45 Hz and 60–100 Hz). The gamma CMC started about 200 ms before, ended about 300 ms after button-press and showed a biphasic time-course with the maximal peak amplitude from 60 to 80 ms after button-press ( Fig. 1 ). The main finding is a significant modulation of gamma band CMC in the sequence blocks compared to [Bl]. Interestingly, this increase occurred in a later phase of the motor response after button press ( Fig. 1 ) indicating stronger ‘afferent’ directionality and was already observed in the first sequence blocks even before reaction time decreased. Therefore, gamma CMC might contribute to the extraction of the implicit motor sequence and facilitate the cortical reorganization of motor program encoding.

Increased serum and musculotendinous fibrogenic proteins following persistent low-grade inflammation in a rat model of long-term upper extremity overuse.

We examined the relationship between grip strength declines and muscle-tendon responses induced by long-term performance of a high-repetition, low-force (HRLF) reaching task in rats. We hypothesized that grip strength declines would correlate with inflammation, fibrosis and degradation in flexor digitorum muscles and tendons. Grip strength declined after training, and further in weeks 18 and 24, in reach limbs of HRLF rats. Flexor digitorum tissues of reach limbs showed low-grade increases in inflammatory cytokines: IL-1β after training and in week 18, IL-1α in week 18, TNF-α and IL-6 after training and in week 24, and IL-10 in week 24, with greater increases in tendons than muscles. Similar cytokine increases were detected in serum with HRLF: IL-1α and IL-10 in week 18, and TNF-α and IL-6 in week 24. Grip strength correlated inversely with IL-6 in muscles, tendons and serum, and TNF-α in muscles and serum. Four fibrogenic proteins, TGFB1, CTGF, PDGFab and PDGFbb, and hydroxyproline, a marker of collagen synthesis, increased in serum in HRLF weeks 18 or 24, concomitant with epitendon thickening, increased muscle and tendon TGFB1 and CTGF. A collagenolytic gelatinase, MMP2, increased by week 18 in serum, tendons and muscles of HRLF rats. Grip strength correlated inversely with TGFB1 in muscles, tendons and serum; with CTGF-immunoreactive fibroblasts in tendons; and with MMP2 in tendons and serum. Thus, motor declines correlated with low-grade systemic and musculotendinous inflammation throughout task performance, and increased fibrogenic and degradative proteins with prolonged task performance. Serum TNF-α, IL-6, TGFB1, CTGF and MMP2 may serve as serum biomarkers of work-related musculoskeletal disorders, although further studies in humans are needed.

Use of ultrasonic and pepsin treatment in tandem for collagen extraction from meat industry by-products

Relatively little attention is paid to collagen-rich cattle short tendons (musculus extensor communis, musculus flexor digitorum, musculus digitorum profundis) as a source of high content and relatively pure collagen, a meat-processing by-product that is used to a minimal extent. Thus, suitable extraction processes from a meat production by-product to gain intact collagen is promising, which thus become interesting from an economic and environmental point of view. Two extraction methods were compared: a 48 h pepsin treatment using 0.5 mol L⁻¹ acetic acid and an extraction using pepsin treatment after ultrasonic treatment in a 0.5 mol L⁻¹ acetic acid solution (the total ultrasonic and pepsin treatment time was 48 h). The results indicated that the optimal conditions for the extraction of collagen from cattle tendon with the ultrasonic-pepsin tandem method is: 4°C, tendon pre-swollen for 12 h in 0.5 mol L⁻¹ acetic acid, pepsin amount: 50 U mg⁻¹ of sample, ultrasonic-pepsin tandem treatment time for 18 h and 30 h, respectively. Extracted cattle tendon collagen using ultrasonic and pepsin treatment in tandem was characterised by amino acid analysis, SDS-PAGE, FT-IR, solubility and thermal denaturation temperature. The results show that the ultrasonic-pepsin tandem method can effectively improve the efficiency of pepsin extraction of natural collagen without any compromise of the resultant collagen quality. This study provides a favourable process to deal with poorly extractable residue by use of ultrasonic and pepsin treatment in tandem. Extracted collagen possesses an intact molecular structure, which is useful and particularly important for its biomedical applications, such as drug delivery systems, wound dressings, and scaffolds.

Direct muscle neurotization after end-to end and end-to-side neurorrhaphy: An experimental study in the rat forelimb model.

The need for the continuous research of new tools for improving motor function recovery after nerve injury is justified by the still often unsatisfactory clinical outcome in these patients. It has been previously shown that the combined use of two reconstructive techniques, namely end-to-side neurorrhaphy and direct muscle neurotization in the rat hindlimb model, can lead to good results in terms of skeletal muscle reinnervation. Here we show that, in the rat forelimb model, the combined use of direct muscle neurotization with either end-to-end or end-to-side neurorrhaphy to reinnervate the denervated flexor digitorum muscles, leads to muscle atrophy prevention over a long postoperative time lapse (10 months). By contrast, very little motor recovery (in case of end-to-end neurorrhaphy) and almost no motor recovery (in case of end-to-side neurorrhaphy) were observed in the grasping activity controlled by flexor digitorum muscles. It can thus be concluded that, at least in the rat, direct muscle neurotization after both end-to-end and end-to-side neurorrhaphy represents a good strategy for preventing denervation-related muscle atrophy but not for regaining the lost motor function.

Performance of repetitive tasks induces decreased grip strength and increased fibrogenic proteins in skeletal muscle: role of force and inflammation.

BackgroundThis study elucidates exposure-response relationships between performance of repetitive tasks, grip strength declines, and fibrogenic-related protein changes in muscles, and their link to inflammation. Specifically, we examined forearm flexor digitorum muscles for changes in connective tissue growth factor (CTGF; a matrix protein associated with fibrosis), collagen type I (Col1; a matrix component), and transforming growth factor beta 1 (TGFB1; an upstream modulator of CTGF and collagen), in rats performing one of two repetitive tasks, with or without anti-inflammatory drugs.Methodology/ResultsTo examine the roles of force versus repetition, rats performed either a high repetition negligible force food retrieval task (HRNF), or a high repetition high force handle-pulling task (HRHF), for up to 9 weeks, with results compared to trained only (TR-NF or TR-HF) and normal control rats. Grip strength declined with both tasks, with the greatest declines in 9-week HRHF rats. Quantitative PCR (qPCR) analyses of HRNF muscles showed increased expression of Col1 in weeks 3–9, and CTGF in weeks 6 and 9. Immunohistochemistry confirmed PCR results, and also showed greater increases of CTGF and collagen matrix in 9-week HRHF rats than 9-week HRNF rats. ELISA, and immunohistochemistry revealed greater increases of TGFB1 in TR-HF and 6-week HRHF, compared to 6-week HRNF rats. To examine the role of inflammation, results from 6-week HRHF rats were compared to rats receiving ibuprofen or anti-TNF-α treatment in HRHF weeks 4–6. Both treatments attenuated HRHF-induced increases in CTGF and fibrosis by 6 weeks of task performance. Ibuprofen attenuated TGFB1 increases and grip strength declines, matching our prior results with anti-TNFα.Conclusions/SignificancePerformance of highly repetitive tasks was associated with force-dependent declines in grip strength and increased fibrogenic-related proteins in flexor digitorum muscles. These changes were attenuated, at least short-term, by anti-inflammatory treatments.

Alteration in Muscle Fatigue Caused by Load-Type Differences during Isometric Flexion of Human Fingers

We measured the endurance time and force and assessed the electromyograms of the flexor digitorum muscle and extensor digitorum muscle in response to 2 types of submaximal fatiguing. The 2 tasks involved isometric contraction of the proximal interphalangeal joint flexor muscles at 50% of the maximum voluntary contraction (MVC) force, which was achieved either by maintaining a constant force while pulling a force transducer (force task) or by supporting an equivalent load while maintaining a constant proximal interphalangeal joint angle (position task). Seven men performed the 2 tasks with their index, middle, and ring fingers. For all 3 fingers, the endurance time for the force task (79 ± 22, 93 ± 46, and 96 ± 56 s for the index, middle, and ring fingers, respectively) was shorter than the corresponding values for the position task (141 ± 105, 147 ± 82, and 212 ± 91 s). The rate of change in amplitude and mean power frequency in the electromyogram did not significantly differ across the 2 tasks. Physiological tremor was computed from the recorded force signal. The physiological tremor initially decreased during both tasks; however, the subsequent increase occurred earlier during the force task.

Morphology of flexor digitorum accessorius muscle

Muscle flexor digitorum accessorius is the muscle of the second layer of the sole. It arises by two heads and gets inserted into the tendon of flexor digitorum longus muscle. A variant of this muscle has often been incriminated in causation of tarsal tunnel syndrome. The action and phylogenetic importance of this muscle remains a matter of disagreement among different researchers. The present study was planned to study the morphology of this muscle in human. The second layer of the sole was dissected in forty-seven cadavers. Origin, insertion and any variations of this muscle were observed. Extension of origin of medial head of this muscle into the tarsal tunnel was also observed. The muscle was found to be very variable. The medial head was more variable, ranging from the complete absence to the bulky fleshy origin. It had fleshy origin from medial surface of calcaneus that extended deep to medio-malleolo calcaneal axis, i.e. into the tarsal tunnel in 80% of the cases. The lateral head was relatively constant and its origin was aponeurotic in all the cases. Insertion of this muscle was very variable, the commonest being insertion on the deep surface of flexor digitorum longus tendon. An accessory muscle-flexor digitorum accessorius longus-was observed in two cases. The bulky medial head appears to be assuming the function of primary toe flexor in the plantigrade man. The origin of medial head extends into the tarsal tunnel in majority. A bulky medial head should be considered as a possible cause of tarsal tunnel syndrome.

Acute Effects of Static Stretching in the Manifestation of Neuromuscular Fatigue in Submaximal Isometric Contraction

PURPOSE: This study aimed to examine the acute effects of a static stretching protocol on the muscle's response to fatigue during an isometric handgrip exercise by means of electromyography (EMG). METHODS: A group of 17 healthy men (mean age (± SD) = 27.1 (2.9) yrs; height = 181 (9.1) cm; and body mass = 78.9 (9.0) kg) performed the fatigue tests applied to the right hand before (NS) and after stretching (ST), which was considered as the intervention group (IG). In addition, two tests were applied to the left hand without stretching and used as the control group (CG). The stretching exercise comprised of three repetitions of static stretching for the wrist flexors lasting 50s each until the discomfort point. The fatigue test consisted of 30s of a handgrip isometric muscle action with a digital dynamometer, and was maintained within a range between 50% and 60% of the MVC, which was monitored by the subject and the tester on the screen of the computer. The tests of IG were performed in a counterbalanced mode with 10 minutes between one test and the other, while the CG only performed the test twice with 10 minutes between each other. During all tests, the subjects had the flexor carpi radialis (FC) and flexor digitorum (FD) muscles monitored by surface EMG. From the EMG data, the root mean square (RMS) values and the mean frequency (MF) were obtained for each consecutives 2s windows of the test, forming time series. The EMG data were normalized in respect to the values obtained during the MVC. From each of the time series, it was determined the coefficient of slope of linear regression, which was used in the comparison of the tests NS and ST and the CG tests by means of paired t tests. RESULTS: The results showed a higher rate of increase in EMG on ST than NS test, both for the FC (p = 0.02) and the FD (p = 0.04) muscles. The same pattern of increased activity was detected in control tests. However, the average of both tests was similar and did not show any statistical difference in CG. A decrease of MF during the tests was observed in the frequency domain, and the FC showed an average decrease rate greater in ST than in the NS test (p = 0.02). Likewise, the average decrease of MF in CG was similar in both tests and no statistical difference was observed. CONCLUSION: It is concluded that static stretching may enhance the manifestation of fatigue and mainly related to their neuromuscular responses, when performed immediately before an isometric contraction. PRACTICAL APPLICATION: It is not recommended to use static stretching before activities that require the application of isometric force over moderate periods of time, as is common in sports that require the task of isometric handgrip muscle actions such as judo and rowing.

Mesenchymal stem cells in a polycaprolactone conduit enhance median-nerve regeneration, prevent decrease of creatine phosphokinase levels in muscle, and improve functional recovery in mice

Although the majority of peripheral-nerve regeneration studies are carried out on the sciatic nerve, lesions of the upper extremities are more common in humans and usually lead to significant physical disabilities. The present study was driven by the hypothesis that a combination of strategies, namely grafts of mesenchymal stem cells (MSC) and resorbable polycaprolactone (PCL) conduits would improve median-nerve regeneration after transection. Mouse median nerves were transected and sutured to PCL tubes that were filled with either green fluorescent protein (GFP +) MSC in DMEM or with DMEM alone. During the post-operative period, animals were tested weekly for flexor digitorum muscle function by means of the grasping test. After 8 weeks, the proximal and middle portions of the PCL tube and the regenerating nerves were harvested and processed for light and electron microscopy. The flexor digitorum muscle was weighed and subjected to biochemical analysis for creatine phosphokinase (CK) levels. Scanning electron microscopy of the PCL tube 8 weeks after implantation showed clear signs of wall disintegration. MSC-treated animals showed significantly larger numbers of myelinated and unmyelinated nerve fibers and blood vessels compared with DMEM-treated animals. The flexor digitorum muscle CK levels were significantly higher in the MSC-treated animals, but muscle weight values did not differ between the groups. Compared with the DMEM-treated group, MSC-treated animals showed, by the grasping test, improved functional performance throughout the period analyzed. Immunofluorescence for S-100 and GFP showed, in a few cases, double-labeled cells, suggesting that transplanted cells may occasionally transdifferentiate into Schwann cells. Our data demonstrate that the polycaprolactone conduit filled with MSC is capable of significantly improving the median-nerve regeneration after a traumatic lesion.

Role of TNF alpha and PLF in bone remodeling in a rat model of repetitive reaching and grasping

We have previously developed a voluntary rat model of highly repetitive reaching that provides an opportunity to study effects of non-weight bearing muscular loads on bone and mechanisms of naturally occurring inflammation on upper limb tissues in vivo. In this study, we investigated the relationship between inflammatory cytokines and matricellular proteins (Periostin-like-factor, PLF, and connective tissue growth factor, CTGF) using our model. We also examined the relationship between inflammatory cytokines, PLF and bone formation processes. Rats underwent initial training for 5 weeks, and then performed a high repetition high force (HRHF) task (12 reaches/min, 60% maximum grip force, 2 h/day, 3 days/week) for 6 weeks. We then examined the effect of training or task performance with or without treatment with a rat specific TNFalpha antibody on inflammatory cytokines, osteocalcin (a bone formation marker), PLF, CTGF, and behavioral indicators of pain or discomfort. The HRHF task decreased grip strength and induced forepaw mechanical hypersensitivity in both trained control and 6-week HRHF animals. Two weeks of anti-TNFalpha treatment improved grip strength in both groups, but did not ameliorate forepaw hypersensitivity. Moreover, anti-TNFalpha treatment attenuated task-induced increases in inflammatory cytokines (TNFalpha, IL-1alpha, and MIP2 in serum; TNFalpha in forelimb bone and muscles) and serum osteocalcin in 6-week HRHF animals. PLF levels in forelimb bones and flexor digitorum muscles increased significantly in 6-week HRHF animals, increases attenuated by anti-TNFalpha treatment. CTGF levels were unaffected by task performance or anti-TNFalpha treatment in 6-week HRHF muscles. In primary osteoblast cultures, TNFalpha, MIP2 and MIP3a treatment increased PLF levels in a dose dependent manner. Also in primary osteoblast cultures, increased PLF promoted proliferation and differentiation, the latter assessed by measuring Runx2, alkaline phosphatase (ALP) and osteocalcin mRNA levels; ALP activity; as well as calcium deposition and mineralization. Increased PLF also promoted cell adhesion in MC3T3-E1 osteoblast-like cell cultures. Thus, tissue loading in vivo resulted in increased TNFalpha, which increased PLF, which then induced anabolic bone formation, the latter results confirmed in vitro.

Animal Model For Resistance Exercise And Memory

It is widely recognized that resistance exercising improves various aspects of cognitive functioning, including explicit long-term memory. However, the mechanisms modulating this improvement have yet to be studied. The main difficulty is developing an animal model to reproduce the adaptive responses involved in resistance training while improving performance on tasks related to hippocampus dependent memory. PURPOSE: To develop an animal model for resistance exercise (in rats) capable of testing improved performance on tasks related to hippocampus dependent memory. METHODS: 20 EPM-1 Wistar adult rats, aged 60-90 days, synchronized to light-dark cycles of 12/12h, lights on at 06:00 a.m, were divided into two groups (experimental / n = 10) and (control / n = 10). The experimental group was subjected to progressive resistance training (PRT) on a ladder-climbing apparatus over eight weeks. After the intervention, both groups were submitted to inhibitory avoidance task. Latency time (sec) was analyzed by an 2-way ANOVA of repeated measures (*p < 0.05), with an a posteriori Tukey test. Forty-eight hours after the task, the rats were sacrificed and the striated skeletal muscle flexor digitorum longus (FDL) of the right leg removed and immediately frozen in liquid nitrogen. Subsequently, the FDL was sectioned in cryostat at -20°C (8 μm), for histological testing, using hematoxylin and eosin staining, and 40× photographs taken. Areas of all fibers photographed were measured (in μm) and the averages were treated statistically (2-way ANOVA of repeated measures (*p < 0.05), with an a posteriori Tukey). RESULTS: The experimental group's latency on the inhibitory avoidance test (460.30 ± 154.56) was higher than the control group's (275.50 ± 214.62) p <0.05. After intervention, experimental group FDL muscles showed larger cross sectional areas (50.62 ± 7.78) than the control group (37.58 ± 3.44) p <0001. The difference in area corresponded to 34.5% muscle hypertrophy. CONCLUSIONS: This animal model was appropriate for studying the mechanisms that modulate memory improvement through resistance exercise, since trained rats showed 34.5% hypertrophy as well as better performance on screening tests to check possible manipulations affecting hippocampus dependent memory. Supported by FAPESP Grant 2008/03083-6

Temporal dynamics of motor integration in Parkinson's disease: towards a concept of time-frequency coding in cortico-basal networks

Introduction. Intraoperative recordings of oscillatory activity from the left subthalamic nucleus (STN), EEG and right forearm EMG (flexor digitorum muscle (FD), extensor digitorum muscle (ED)) were performed in six PD patients during surgery for STN-DBS in order to comprehensively study temporal dynamics of motor integration in distributed networks including STN, M1, and contralateral effector muscles.

Free medial plantar artery perforator flap for finger pulp reconstruction: Report of a series of 10 cases

Treatment of composite tissue loss in the finger pulp is often difficult. The purpose of this report is to present our experience on using medial plantar artery perforator flap for repair of finger pulp defects and to restore fingertip sensation after traumatic injury. The free medial plantar artery perforator (MPAP) flaps were performed for digital pulp reconstruction in ten patients (eight fingertips and two thumbtips) between June, 2006 and December, 2007. This flap blood supply was perforator vessel of medial plantar artery, which was through the intermuscular septum between the abductor hallucis muscle and the flexor digitorum muscle. The recipient vessels were digital artery and dorsal digital vein. The flap was not reinnervated during transfer procedures. The donor sites were closed primarily in all cases. Flap size ranged from 15 x 25 mm to 60 x 20 mm. All flaps were survival. Partial loss occurred in one flap, due to venous congestion caused by excessive stitch tension. The donor sites healed unevenfully in eight cases, but mild wound dehiscence occurred in two cases. The follow-ups ranged from 6 to 29 months with the mean of 18.1 months. The mean of s-2PD and m-2PD were 8.8 mm and 6.8 mm at patients' last visits, respectively. MPAP flaps are good in terms of general morbidity, cosmetic results, and durability. This flap is a valuable alternative method of repairing the glabrous finger pulp and tip defects.

Amplification effects in nerve regeneration after different segment injury: experiment with rabbit median nerve

To investigate the impact of different section injury on the median nerve during peripheral nerve regeneration. 18 New-Zealand rabbits were divided into 3 groups. We took the proximal, intermediate and distal nerve segment as donor nerve, the restore ratio of the number of donator fibers to recipient fibers is 1:4. We took the corresponding right side nerve as control, the restore ratio of the number of donator fibers to recipient fibers is 1:1. We then observed the general condition of regenerated nerve, counted the number of regenerated fibers, measured its conduction of velocity and wet weights of musculus flexor digitorum sublimis 3 months after operation. The numbers of recipient fiber of 3 different groups were as follows: group I: 1747 +/- 375, group I: 1785 +/- 442, group III: 1863 +/- 321; Control goup I: 2234 +/- 364, control group II: 2319 +/- 237, control group III: 2346 +/- 308. The results of conduction of velocity were: group I: 19.5 m/s, group II: 19.9 m/s, group III: 21.3 m/s; Control group I: 57.1 +/- 3.7 m/s, control group I: 56.4 +/- 2.5 m/s, control group III: 56.8 +/- 2.3 m/s. The results of wet weights of musculus flexor digitorum sublines were as follows: group I: 1.7247 +/- 0.0891 g, group II:1.7239 +/- 0.0903 g, group III: 1.7253 +/- 0.0798 g. Control group I: 2.0448 +/- 0.1013 g, control group II: 2.0433 +/- 0.0861 g, control group III: 2.0456 +/- 0.0947 g. The amplification phenomenon exist in every group, the amplified ratio augment according to the distance of the site from neuron, but the conduction of velocity is decreased gradually . The wet weights of musculus flexor digitorum sublines has no significant difference between 3 groups.

Denervation and reinnervation of adult skeletal muscle modulate mRNA expression of neuregulin‐1 and ErbB receptors

Skeletal muscle atrophy represents one of the main causes of poor outcome of microsurgical nerve reconstruction. Recent studies have pointed to the importance of the neuregulin/ErbB signaling pathway in the development and regeneration of the neuromuscular system. Here, we show by immunohistochemistry, RT-PCR, and Western blotting analyses, in an in vivo model of adult skeletal muscle denervation/reinnervation, that expression of Neuregulin1 (NRG1) and ErbB receptors is regulated by the innervation condition. We found out that a significant upregulation of the alpha-, but not beta-, isoform of NRG1, as well as of ErbB2, ErbB3, and ErbB4-cyt1 isoform occurs as a consequence of denervation of flexor digitorum muscles of the rat forelimb by median nerve transection. Moreover, after tubulization median nerve repair, and consequent muscle reinnervation, all messengers of the NRG1/ErbB system are promptly downregulated. Therefore, our results suggest the existence of a alpha-NRG1-mediated autocrine and/or paracrine trophic loop in skeletal muscles that is activated after denervation and promptly deactivated after nerve reconstruction. This myotrophic loop is a promising therapeutic target for the prevention of muscle atrophy. Yet, the recent demonstration of a similar alpha-NRG1-mediated gliotrophic loop in denervated Schwann cells provides a possible explanation for the effectiveness of muscle conduits for tubulization nerve repair.

Changes of Extremity and Laryngeal Muscle Electromyographic Amplitudes After Intravenous Administration of Vecuronium

To compare electromyographic (EMG) amplitude changes in extremity and laryngeal muscles after vecuronium administration and study the effects of topical lidocaine on laryngeal EMG in a swine model. Prospective animal study. Electrically evoked EMG activities were recorded from the vocalis muscles (directly and via an EMG endotracheal tube) and from the flexor digitorum muscles before and after intravenous vecuronium administration. EMG amplitudes were followed for 30 minutes after vecuronium injection together with monitoring of limb twitches to train-of-four stimulation. The testing was repeated after a 30-minute wash-out period and with topical lidocaine. EMG amplitude recovery occurred sooner and more quickly in flexor digitorum muscle than in vocalis muscles. Reappearance of four twitches corresponded to EMG amplitude recovery to about 80% of the baseline in flexor digitorum muscles and to about half-baseline size in vocalis muscles. EMG amplitudes were generally lower at the start of the second round testing than the first round, with somewhat slower recovery in vocalis muscles. In contrast to reports by others in human studies, extremity muscles seem to be more resistant to vecuronium at 0.1 mg/kg than laryngeal muscles in the swine. Reappearance of four twitches corresponds to 50% of laryngeal EMG recovery and indicates adequate condition for monitoring electrically evoked laryngeal EMG activities. This study is inconclusive regarding the effects of topically applied lidocaine on laryngeal EMG amplitudes. Translation of these data to humans should be done with caution.