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Sample records for abductor muscle weakness

  1. Resisted side-stepping: the effect of posture on hip abductor muscle activation

    PubMed Central

    Berry, Justin W.; Lee, Theresa S.; Foley, Hanna D.; Lewis, Cara L.

    2016-01-01

    Study Design Controlled laboratory study, repeated-measures design. Objectives To compare hip abductor muscle activity and hip and knee joint kinematics in the moving limb to the stance limb during resisted side-stepping and also to determine if muscle activity was affected by the posture (upright standing versus squat) used to perform the exercise. Background Hip abductor weakness has been associated with a variety of lower extremity injuries. Resisted side-stepping is often used as an exercise to increase strength and endurance of the hip abductors. Exercise prescription would benefit from knowing the relative muscle activity level generated in each limb and for different postures during the side-stepping exercise. Methods Twenty-four healthy adults participated in this study. Kinematics and surface electromyographic (EMG) data from the gluteus maximus, gluteus medius, and tensor fascia lata (TFL) were collected as participants performed side-stepping with a resistive band around the ankle while maintaining each of 2 postures: 1) upright standing and 2) squat. Results Mean normalized EMG signal amplitude of the gluteus maximus, gluteus medius, and TFL was higher in the stance limb than the moving limb (P≤.001). Gluteal muscle activity was higher, while TFL muscle activity was lower, in the squat posture compared to the upright standing posture (P<.001). Hip abduction excursion was greater in the stance limb than in the moving limb (P<.001). Conclusions The 3 hip abductor muscles respond differently to the posture variations of side-stepping exercise in healthy individuals. When prescribing resisted side-stepping exercises, therapists should consider the differences in hip abductor activation across limbs and variations in trunk posture. PMID:26161629

  2. Muscle Weakness

    PubMed Central

    Al Kaissi, Ali; Ryabykh, Sergey; Ochirova, Polina; Kenis, Vladimir; Hofstätter, Jochen G.; Grill, Franz; Ganger, Rudolf; Kircher, Susanne Gerit

    2017-01-01

    Marked ligamentous hyperlaxity and muscle weakness/wasting associated with awkward gait are the main deficits confused with the diagnosis of myopathy. Seven children (6 boys and 1 girl with an average age of 8 years) were referred to our department because of diverse forms of skeletal abnormalities. No definitive diagnosis was made, and all underwent a series of sophisticated investigations in other institutes in favor of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Three children (2 boys and 1 girl) were compatible with the diagnosis of progressive pseudorheumatoid chondrodysplasia. The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6. Klinefelter syndrome was the diagnosis in 2 boys. Karyotyping confirmed 47,XXY (aneuploidy of Klinefelter syndrome). And 2 boys were finally diagnosed with Morquio syndrome (MPS type IV A) as both showed missense mutations in the N-acetylgalactosamine-sulfate sulfatase gene. Misdiagnosis can lead to the initiation of a long list of sophisticated investigations. PMID:28210640

  3. The influence of hip abductor weakness on frontal plane motion of the trunk and pelvis in patients with cerebral palsy.

    PubMed

    Krautwurst, Britta K; Wolf, Sebastian I; Heitzmann, Daniel W W; Gantz, Simone; Braatz, Frank; Dreher, Thomas

    2013-04-01

    Trendelenburg walking pattern is a common finding in various disorders, including cerebral palsy (CP), where it is seen in children and adults. Clinically, this deviation is viewed as a consequence of hip abductor weakness resulting in pelvic obliquity. Trunk lean to the ipsilateral side is a common compensatory mechanism to counteract pelvic obliquity and to maintain gait stability. However, no published investigations objectively address pelvic and trunk motions in the frontal plane or examine the correlation with hip abductor weakness in patients with CP. We selected 375 ambulatory (GMFCS I-III) patients with spastic bilateral CP and 24 healthy controls from our gait laboratory database. They had all undergone a standardized three-dimensional analysis of gait, including trunk motion, and a clinical examination including hip abductor strength testing. Selected frontal plane kinematic and kinetic parameters were investigated and statistically tested for correlation (Spearman rank) with hip abductor strength. Only a weak (r=0.278) yet highly significant correlation between trunk lean and hip abductor strength was found. Hip abductor weakness was accompanied by decreased hip abduction moment. However, no significant differences in pelvic position were found between the different strength groups, indicating that the pelvis remained stable regardless of the patients' strength. Our findings indicate that weak hip abductors in patients with CP are accompanied by increased trunk lean to the ipsilateral side while pelvic position is preserved by this compensatory mechanism. However, since this correlation is weak, other factors influencing lateral trunk lean should be considered. In patients with severe weakness of the hip abductors compensatory trunk lean is no longer fully able to stabilize the pelvis, and frontal pelvic kinematics differs from normal during loading response. The results indicate that the stable pelvic position seems to be of greater importance than

  4. Recurrence of Hypertrophic Abductor Digiti Minimi Muscle of the Foot After Subtotal Resection.

    PubMed

    Schmauss, Daniel; Harder, Yves; Machens, Hans-Guenther; Lohmeyer, Joern Andreas

    2016-01-01

    Soft tissue tumors of the foot are rare, and the diagnosis is often difficult. Surgery is indicated if pain, discomfort, or functional impairment is present or to rule out malignancy. We present the case of a 14-year-old female with a painless swelling at the lateral aspect of her right foot. After radiologic imaging, including ultrasonography and magnetic resonance imaging (MRI), we performed a subtotal resection of the abductor digiti minimi muscle, preserving its motor nerve. Four months later, recurrence of the soft tissue mass was observed. MRI revealed hypertrophy of the small muscles of the foot, including the abductor digiti minimi, quadratus plantae, and flexor digiti minimi brevis. Functional impairment resulted in complete excision of the remnant abductor digiti minimi muscle and partial excision of the flexor digiti minimi brevis muscle another 7 months later. Twelve months after the secondary surgery, neither clinical nor radiologic signs of a second recurrence were found. At the last follow-up visit, the patient was satisfied with the contour of her foot and not hindered at all during sporting activities. Our findings demonstrate that subtotal resection of a bulky muscle, preserving its motor nerve, can result in reactive hypertrophy of the remnant muscle part. The patient must be informed that partial excision of an innervated muscle could result in reactive hypertrophy and must be contrasted with radical muscle excision that might be more likely to result in functional impairment.

  5. The Influence of Hip Abductor Weakness on Frontal Plane Motion of the Trunk and Pelvis in Patients with Cerebral Palsy

    ERIC Educational Resources Information Center

    Krautwurst, Britta K.; Wolf, Sebastian I.; Heitzmann, Daniel W. W.; Gantz, Simone; Braatz, Frank; Dreher, Thomas

    2013-01-01

    Trendelenburg walking pattern is a common finding in various disorders, including cerebral palsy (CP), where it is seen in children and adults. Clinically, this deviation is viewed as a consequence of hip abductor weakness resulting in pelvic obliquity. Trunk lean to the ipsilateral side is a common compensatory mechanism to counteract pelvic…

  6. Experimentally Reduced Hip-Abductor Muscle Strength and Frontal-Plane Biomechanics During Walking

    PubMed Central

    Pohl, Michael B.; Kendall, Karen D.; Patel, Chirag; Wiley, J. Preston; Emery, Carolyn; Ferber, Reed

    2015-01-01

    Context: Researchers have postulated that reduced hip-abductor muscle strength may have a role in the progression of knee osteoarthritis by increasing the external knee-adduction moment. However, the relationship between hip-abductor strength and frontal-plane biomechanics remains unclear. Objective: To experimentally reduce hip-abduction strength and observe the subsequent changes in frontal-plane biomechanics. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Eight healthy, recreationally active men (age = 27 ± 6 years, height = 1.75 ± 0.11 m, mass = 76.1 ± 10.0 kg). Intervention(s): All participants underwent a superior gluteal nerve block injection to reduce the force output of the hip-abductor muscle group. Main Outcome Measure(s): Maximal isometric hip-abduction strength and gait biomechanical data were collected before and after the injections. Gait biomechanical variables collected during walking consisted of knee- and hip-adduction moments and impulses and the peak angles of contralateral pelvic drop, hip adduction, and ipsilateral trunk lean. Results: Hip-abduction strength was reduced after the injection (P = .001) and remained lower than baseline values at the completion of the postinjection gait data collection (P = .02). No alterations in hip- or knee-adduction moments (hip: P = .11; knee: P = .52) or impulses (hip: P = .16; knee: P = .41) were found after the nerve block. Similarly, no changes in angular kinematics were observed for contralateral pelvic drop (P = .53), ipsilateral trunk lean (P = .78), or hip adduction (P = .48). Conclusions A short-term reduction in hip-abductor strength was not associated with alterations in the frontal-plane gait biomechanics of young, healthy men. Further research is needed to determine whether a similar relationship is true in older adults with knee osteoarthritis. PMID:25875071

  7. Isokinetic imbalance of adductor-abductor hip muscles in professional soccer players with chronic adductor-related groin pain.

    PubMed

    Belhaj, K; Meftah, S; Mahir, L; Lmidmani, F; Elfatimi, A

    2016-11-01

    This study aims to compare the isokinetic profile of hip abductor and adductor muscle groups between soccer players suffering from chronic adductor-related groin pain (ARGP), soccer players without ARGP and healthy volunteers from general population. Study included 36 male professional soccer players, who were randomly selected and followed-up over two years. Of the 21 soccer players eligible to participate in the study, 9 players went on to develop chronic ARGP and 12 players did not. Ten healthy male volunteers were randomly selected from the general population as a control group. Comparison between the abductor and adductor muscle peak torques for players with and without chronic ARGP found a statistically significant difference on the dominant and non-dominant sides (p < .005), with the abductor muscle significantly stronger than the adductor muscle. In the group of healthy volunteers, the adductor muscle groups were significantly stronger than the abductor muscle groups on both dominant and non-dominant sides (p < .05). For the group of players who had developed chronic ARGP, abductor-adductor torque ratios were significantly higher on the affected side (p = .008). The adductor muscle strength was also significantly decreased on the affected side. This imbalance appears to be a risk factor for adductor-related groin injury. Therefore, restoring the correct relationship between these two agonist and antagonist hip muscles may be an important preventative measure that should be a primary concern of training and rehabilitation programmes.

  8. Effects of perioperative factors and hip geometry on hip abductor muscle strength during the first 6 months after anterolateral total hip arthroplasty

    PubMed Central

    Ikeda, Takashi; Jinno, Tetsuya; Aizawa, Junya; Masuda, Tadashi; Hirakawa, Kazuo; Ninomiya, Kazunari; Suzuki, Kouji; Morita, Sadao

    2017-01-01

    [Purpose] The importance and effect of hip joint geometry on hip abductor muscle strength are well known. In addition, other perioperative factors are also known to affect hip abductor muscle strength. This study examined the relative importance of factors affecting hip abductor muscle strength after total hip arthroplasty. [Subjects and Methods] The subjects were 97 females with osteoarthritis scheduled for primary unilateral THA. The following variables were assessed preoperatively and 2 and 6 months after surgery: isometric hip abductor strength, radiographic analysis (Crowe class, postoperative femoral offset (FO)), Frenchay Activities Index, compliance rate with home exercise, Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), and demographic data. Factors related to isometric hip abductor muscle strength 2 and 6 months after surgery were examined. [Results] Significant factors related to isometric hip abductor muscle strength at 2 and 6 months after surgery were, in extraction order: 1. isometric hip abductor muscle strength in the preoperative period; 2. BMI; and 3. the JHEQ mental score at 2 and 6 months after surgery. [Conclusion] Preoperative factors and postoperative mental status were related to postoperative isometric hip abductor strength. FO was not extracted as a significant factor related to postoperative isomeric hip abductor strength. PMID:28265161

  9. Effects of perioperative factors and hip geometry on hip abductor muscle strength during the first 6 months after anterolateral total hip arthroplasty.

    PubMed

    Ikeda, Takashi; Jinno, Tetsuya; Aizawa, Junya; Masuda, Tadashi; Hirakawa, Kazuo; Ninomiya, Kazunari; Suzuki, Kouji; Morita, Sadao

    2017-02-01

    [Purpose] The importance and effect of hip joint geometry on hip abductor muscle strength are well known. In addition, other perioperative factors are also known to affect hip abductor muscle strength. This study examined the relative importance of factors affecting hip abductor muscle strength after total hip arthroplasty. [Subjects and Methods] The subjects were 97 females with osteoarthritis scheduled for primary unilateral THA. The following variables were assessed preoperatively and 2 and 6 months after surgery: isometric hip abductor strength, radiographic analysis (Crowe class, postoperative femoral offset (FO)), Frenchay Activities Index, compliance rate with home exercise, Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), and demographic data. Factors related to isometric hip abductor muscle strength 2 and 6 months after surgery were examined. [Results] Significant factors related to isometric hip abductor muscle strength at 2 and 6 months after surgery were, in extraction order: 1. isometric hip abductor muscle strength in the preoperative period; 2. BMI; and 3. the JHEQ mental score at 2 and 6 months after surgery. [Conclusion] Preoperative factors and postoperative mental status were related to postoperative isometric hip abductor strength. FO was not extracted as a significant factor related to postoperative isomeric hip abductor strength.

  10. System identification of evoked mechanomyogram from abductor pollicis brevis muscle in isometric contraction.

    PubMed

    Uchiyama, Takanori; Sakai, Hiroaki

    2013-12-01

    The purpose of this study is to verify the applicability of a sixth-order model to the mechanomyogram (MMG) system of the parallel-fibered muscle, which was identified from the MMG of the pennation muscle. The median nerve was stimulated, and an MMG and torque of the abductor pollicis brevis muscle were measured. The MMGs were detected with either a capacitor microphone or an acceleration sensor. The transfer functions between stimulation and the MMG and between stimulation and torque were identified by the singular value decomposition method. The torque and the MMG, which were detected with a capacitor microphone, DMMG, were approximated with a second- and a third-order model, respectively. The natural frequency of the torque, reflecting longitudinal mechanical characteristics, did not show a significant difference from that of the DMMG. The MMG detected with an acceleration sensor was approximated with a fourth-order model. The natural frequencies of the AMMG reflecting the muscle and subcutaneous tissue in the transverse direction were obtained. Both DMMG and AMMG have to be measured to investigate the model of the MMG system for parallel-fibered muscle. The MMG system of parallel-fibered muscle was also modeled with a sixth-order model.

  11. The effect of hip abductor exercise on muscle strength and trunk stability after an injury of the lower extremities

    PubMed Central

    Kak, Hwang-Bo; Park, Sun-Ja; Park, Byun-Joon

    2016-01-01

    [Purpose] The gluteus medius, a hip abductor, controls femoral movement and stabilizes the pelvis during lower extremity mobilization. [Subjects] This study enrolled 24 subjects into control and experimental groups. [Methods] This randomized controlled study included patients who underwent arthroscopy after meniscus injury and started a rehabilitative exercise program 8 weeks after surgery. Subjects were divided into the experimental gluteus medius resistance exercise group (n=12) and the control group (n=12). The study investigated muscle strength and balance of the flexors, extensors, and abductors of the knee for 8 weeks. [Results] Strengths of knee extensors in patients who underwent rehabilitative exercise for 8 weeks were measured. Strength of the knee extensors of the experimental and control groups increased by 40% and 31%, respectively; strength of the hip flexors of the experimental and control groups increased by 31% and 18%, respectively. Strength of the hip joint muscles showed a 40% increase in the experimental group and a 14% increase in the control group. However, there was a significant difference (18%) in muscle strength of the hip abductors between the groups. Measurements of trunk lateral flexion showed a difference within a group, but no intergroup difference was found. [Conclusion] This study investigated the effect of hip abductor exercise on muscular strength and trunk stability in patients with a meniscus injury. PMID:27134387

  12. Responses of human hip abductor muscles to lateral balance perturbations during walking.

    PubMed

    Hof, A L; Duysens, J

    2013-10-01

    Lateral stability during gait is of utmost importance to maintain balance. This was studied on human subjects walking on a treadmill who were given 100-ms perturbations of known magnitude and timing with respect to the gait cycle by means of a computer-controlled pneumatic device. This method has the advantage that the same perturbations can be given at different phases of the stride cycle, thereby allowing an analysis of the phase dependency of the responses in the primary muscles involved. After an inward push, e.g., a push toward the left during right stance, the left foot in the step to follow is placed more to the left (outward strategy). The hypothesis was that this movement is caused by automatic unvoluntary muscle activity. This turned out to be the case: the abduction movement follows EMG responses in the left abductor muscle, gluteus medius, in response to the push. Two responses, with latencies of 100 and 170 ms, and a late reaction >270 ms can be discerned. All three responses are phase dependent; they show facilitation in swing and no response in stance, in contrast to the normal walking activity (background). This independence of the background activity suggests a premotoneuronal gating of these responses, reminiscent of phase-dependent modulation of electrically elicited reflexes. It is concluded that facilitating pathways are opened independent of normal background activation to enable appropriate actions to restore balance after a mediolateral perturbation.

  13. Silent periods in the abductor pollicis brevis muscle in patients with Parkinson's disease.

    PubMed

    Nakashima, K; Takahashi, K

    1992-01-01

    Silent periods in the abductor pollicis brevis muscle, produced by electrical stimulation of the median nerve at the wrist or the palmar side of the index finger, were studied in 14 patients with Parkinson's disease (PD) and eight control subjects. Prior to the stimulation, background electromyographic activity showed no differences between normal subjects and patients with PD. Following the H-reflex after median nerve stimulation, two suppressive phases were observed: early (SP1) and late (SP2). Electrical stimulation of the palmar side of the index finger elicited two suppressive phases at almost the same latencies. The latency and duration of SP1 and SP2 and the degree of SP1, produced by electrical stimulation of the median nerve and the palmar side of the index finger in patients with PD, were normal. The degree of SP2 produced by electrical stimulation of the palmar side of the index finger in patients with PD was lower than that in normal subjects, although the degree of SP2 produced by median nerve stimulation in patients with PD did not differ from that in normal subjects. Suppression produced by cutaneous stimulation in the Parkinsonian hand may be low.

  14. Changes in EMG coherence between long and short thumb abductor muscles during human development.

    PubMed

    Farmer, Simon F; Gibbs, John; Halliday, David M; Harrison, Linda M; James, Leon M; Mayston, Margaret J; Stephens, John A

    2007-03-01

    In adults, motoneurone pools of synergistic muscles that act around a common joint share a common presynaptic drive. Common drive can be revealed by both time domain and frequency domain analysis of EMG signals. Analysis in the frequency domain reveals significant coherence in the range 1-45 Hz, with maximal coherence in low (1-12 Hz) and high (16-32 Hz) ranges. The high-frequency range depends on cortical drive to motoneurones and is coherent with cortical oscillations at approximately 20 Hz frequencies. It is of interest to know whether oscillatory drive to human motoneurone pools changes with development. In the present study we examined age-related changes in coherence between rectified surface EMG signals recorded from the short and long thumb abductor muscles during steady isometric contraction obtained while subjects abducted the thumb against a manipulandum. We analysed EMG data from 36 subjects aged between 4 and 14 years, and 11 adult subjects aged between 22 and 59 years. Using the techniques of pooled coherence analysis and the chi(2) difference of coherence test we demonstrate that between the ages of 7 and 9 years, and 12 and 14 years, there are marked increases in the prevalence and magnitude of coherence at frequencies between 11 and 45 Hz. The data from subjects aged 12-14 years were similar to those obtained from adult controls. The most significant differences between younger children and the older age groups were detected at frequencies close to 20 Hz. We believe that these are the first reported results demonstrating significant late maturational changes in the approximately 20 Hz common oscillatory drive to human motoneurone pools.

  15. Discharge properties of motor units of the abductor hallucis muscle during cramp contractions.

    PubMed

    Minetto, Marco A; Holobar, Ales; Botter, Alberto; Farina, Dario

    2009-09-01

    We analyzed individual motor units during electrically elicited cramp contractions with the aim of characterizing the variability and degree of common oscillations in their discharges. Intramuscular and surface electromyographic (EMG) signals were detected from the abductor hallucis muscle of 11 healthy subjects (age 27.0+/-3.7 yr) during electrically elicited cramps. In all, 48 motor units were identified from the intramuscular EMG. These motor units were active for 23.6+/-16.2 s, during which their average discharge rate was 14.5+/-5.1 pulses/s (pps) and their minimum and maximum rates were, respectively, 6.0+/-0.8 and 25.0+/-8.0 pps (P<0.001). The coefficient of variation for the interspike interval (ISI) was 44.6+/-9.7% and doublet discharges constituted 4.1+/-4.7% of the total number of discharges. In 38 motor units, the SD of the ISI was positively correlated to the mean ISI (R2=0.37, P<0.05). The coherence spectrum between smoothed discharge rates of pairs of motor units showed one significant peak at 1.4+/-0.4 Hz for 29 of the 96 motor unit pairs and two significant peaks at 1.3+/-0.5 and 1.5+/-0.5 Hz for 8 motor unit pairs. The cross-correlation function between pairs of discharge rates showed a significant peak (0.52+/-0.11) in 26 motor unit pairs. In conclusion, motor units active during cramps showed a range of discharge rates similar to that observed during voluntary contractions but larger ISI variability, probably due to large synaptic noise. Moreover, the discharge rates of the active motor units showed common oscillations.

  16. Effect of experimentally reduced distal sensation on postural response to hip abductor/ankle evertor muscle vibration.

    PubMed

    Glasser, S; Collings, R; Paton, J; Marsden, J

    2015-07-01

    This study assessed whether postural responses induced by vibratory perturbations of the hip abductors and ankle evertors, were modified when distal tactile sensation was experimentally reduced through cooling. Sixteen healthy subjects were investigated pre and post cooling. Subjects stood with their eyes closed with a stance width of 4 cm. A 2s vibratory stimulus was applied to the left or right hip abductor or ankle evertor muscle. The order of the site and side of the stimulation was randomised. The postural response to hip abductor and ankle evertor vibration was recorded using 3D motion analysis (Codamotion, Leicestershire). Medio-lateral centre of pressure motion was simultaneously recorded during quiet standing via a force plate (Kistler, UK). Pre-cooling people responded to unilateral ankle vibration with an ipsilateral translation and tilt of the pelvis, and an ipsilateral tilt of the trunk. People responded to unilateral hip vibration with a contralateral translation and tilt of the pelvis, and an ipsilateral tilt of the trunk. Following an experimental reduction in distal tactile sensation there was a significant reduction in the amplitude of pelvic tilt in response to ankle vibration (F(6.2)=P<0.05) and a significant increase in amplitude of pelvic tilt in response to hip vibration (F(5.2)=P<0.05). This suggests that the sensitivity to artificial stimulation of hip proprioception increases with distal cooling, possibly indicating a change in the gain/weighting placed upon sensory information from the hips.

  17. [Acute muscle weakness: differential diagnoses].

    PubMed

    Antoniuk, Sérgio A

    2013-09-06

    Acute muscle weakness, a common disorder in pediatrics, can occur from impairment of any part of the motor unit, including the upper motor neuron, lower motor neuron, peripheral nerve, neuromuscular junction or muscle. It usually manifests itself as an acute or hyperacute motor disorder of progressive or rapidly progressive course. Acute muscle weakness is a neuromuscular emergency, especially if it affects the respiratory or oropharyngeal musculature. The location of the motor weakness and associated neurological signs and symptoms usually indicate the location of the lesion. The onset, speed and clinical evolution, as well as other data from the patient's history, suggest the pathophysiological differential diagnosis. Successful treatment depends on the immediate and correct differential diagnosis. This paper presents the main differential diagnosis of main neuromuscular diseases that cause acute muscle weakness in children.

  18. Botulinum toxin therapy for abductor spasmodic dysphonia.

    PubMed

    Woodson, Gayle; Hochstetler, Heidi; Murry, Thomas

    2006-03-01

    Botulinum toxin has been widely accepted as an effective therapy for controlling the symptoms of adductor spasmodic dysphonia (ADSD). Reported experience with botulinum treatment for abductor spasmodic dysphonia (ABSD) has been less impressive. Factors that may impair outcomes for ABSD include differences in the pathophysiology of ADSD and ABSD and limitation of maximal dose from airway restriction with posterior cricoarytenoid muscle (PCA) weakness. We report our experience with botulinum injection of the PCA with an asymmetric dose escalation protocol, based on clinical observations that in ABSD, abductor spasms are often stronger on one side, usually the left. The nondominant side was injected with 1.25 units. Dominant side dose began at 5 units, with step-wise increments of 5 units per week until one of three endpoints was reached: Elimination of breathy voice breaks, complete abductor paralysis of the dominant side, or airway compromise. Fourteen of 17 patients achieved good or fair voice, with dominant-side doses ranging from 10 to 25 units. Exercise intolerance limited PCA dose in two patients. One patient had persisting breathiness that improved with medialization thyroplasty. Asymmetric botulinum toxin injection into PCA muscles can suppress abductor spasm in patients with ABSD, but breathiness may persist, because of inadequate glottal closure.

  19. Automatic assessment of volume asymmetries applied to hip abductor muscles in patients with hip arthroplasty

    NASA Astrophysics Data System (ADS)

    Klemt, Christian; Modat, Marc; Pichat, Jonas; Cardoso, M. J.; Henckel, Joahnn; Hart, Alister; Ourselin, Sebastien

    2015-03-01

    Metal-on-metal (MoM) hip arthroplasties have been utilised over the last 15 years to restore hip function for 1.5 million patients worldwide. Althoug widely used, this hip arthroplasty releases metal wear debris which lead to muscle atrophy. The degree of muscle wastage differs across patients ranging from mild to severe. The longterm outcomes for patients with MoM hip arthroplasty are reduced for increasing degrees of muscle atrophy, highlighting the need to automatically segment pathological muscles. The automated segmentation of pathological soft tissues is challenging as these lack distinct boundaries and morphologically differ across subjects. As a result, there is no method reported in the literature which has been successfully applied to automatically segment pathological muscles. We propose the first automated framework to delineate severely atrophied muscles by applying a novel automated segmentation propagation framework to patients with MoM hip arthroplasty. The proposed algorithm was used to automatically quantify muscle wastage in these patients.

  20. Effect of toe-spread-out exercise on hallux valgus angle and cross-sectional area of abductor hallucis muscle in subjects with hallux valgus

    PubMed Central

    Kim, Moon-Hwan; Yi, Chung-Hwi; Weon, Jong-Hyuck; Cynn, Heon-Seock; Jung, Do-Young; Kwon, Oh-Yun

    2015-01-01

    [Purpose] This study investigated whether the toe-spread-out exercise affects the hallux valgus angle, the cross-sectional area of the abductor hallucis muscle, and the hallux valgus angle during active abduction. [Subjects and Methods] Twenty-four subjects with hallux valgus were randomly assigned to orthosis and orthosis plus toe-spread-out exercise groups. The orthosis group wore the orthosis for 8 weeks, while the orthosis plus toe-spread-out group also performed the toe-spread-out exercise. The hallux valgus angle, the cross-sectional area of the abductor hallucis muscle, and the hallux valgus angle during active abduction were measured initially and after 8 weeks by radiography and ultrasonography. [Results] While there were no significant changes in the three parameters in the orthosis group, there were significant differences in the orthosis plus toe-spread-out exercise group after 8 weeks. In addition there were significant differences in the three measures between the two groups. [Conclusion] The toe-spread-out exercise reduces the hallux valgus angle and hallux valgus angle during active abduction, and increases the cross-sectional area of the abductor hallucis muscle. The toe-spread-out exercise is recommended for patients with mild to moderate hallux valgus. PMID:25995546

  1. Skeletal muscle weakness in osteogeneis imperfecta mice

    PubMed Central

    Gentry, Bettina A; Ferreira, J. Andries; McCambridge, Amanda J.; Brown, Marybeth; Phillips, Charlotte L.

    2010-01-01

    Exercise intolerance, muscle fatigue and weakness are often-reported, little-investigated concerns of patients with osteogenesis imperfecta (OI). OI is a heritable connective tissue disorder hallmarked by bone fragility resulting primarily from dominant mutations in the proα1(I) or proα2(I) collagen genes and the recently discovered recessive mutations in post-translational modifying proteins of type I collagen. In this study we examined the soleus (S), plantaris (P), gastrocnemius (G), tibialis anterior (TA) and quadriceps (Q) muscles of mice expressing mild (+/oim) and moderately severe (oim/oim) OI for evidence of inherent muscle pathology. In particular, muscle weight, fiber cross-sectional area (CSA), fiber type, fiber histomorphology, fibrillar collagen content, absolute, relative and specific peak tetanic force (Po, Po/mg and Po/CSA respectively) of individual muscles were evaluated. Oim/oim mouse muscles were generally smaller, contained less fibrillar collagen, had decreased Po and an inability to sustain Po for the 300 ms testing duration for specific muscles; +/oim mice had a similar but milder skeletal muscle phenotype. +/oim mice had mild weakness of specific muscles but were less affected than their oim/oim counterparts which demonstrated readily apparent skeletal muscle pathology. Therefore muscle weakness in oim mice reflects inherent skeletal muscle pathology. PMID:20619344

  2. Operative outcome of partial plantar fasciectomy and neurolysis to the nerve of the abductor digiti minimi muscle for recalcitrant plantar fasciitis.

    PubMed

    Conflitti, Joseph M; Tarquinio, Thom A

    2004-07-01

    A retrospective review was conducted of 23 patients (26 feet) to assess operative outcome of partial plantar fasciectomy and neurolysis to the nerve of the abductor digiti minimi muscle for recalcitrant plantar fasciitis. Nonsurgical treatment was implemented in all patients with no relief of symptoms (average 20.8 months) prior to surgery. Using a visual analog pain scale (0-10), the average preoperative pain was 9.2 (range, 8-10). Prior to surgery, 65.2% of patients had severe limitations of activity, and 34.8% of patients had moderate limitations of activity. An average 25.3-month follow-up (range, 8-51) was performed by telephone interview. Average postoperative pain decreased to 1.7 using the same visual analog scale. Thirteen patients (57%) had no functional limitations postoperatively and nine patients (39%) had minimal functional limitations postoperatively. One patient (4%) had moderate functional limitations postoperatively. Twenty patients (87%) were completely satisfied with the surgery, two patients (9%) were satisfied with reservations, and one patient (4%) was unsatisfied with the surgery. The average period before return to work or daily activities was 1.5 months. Two patients had minor complications of partial wound dehiscence that healed uneventfully and mild dorsal midfoot pain which required temporary use of a boot walker. While the majority of patients with plantar fasciitis can be managed with nonoperative treatment, those patients with recalcitrant plantar fasciitis can be effectively treated with partial plantar fasciectomy and neurolysis to the nerve of the abductor digiti minimi muscle.

  3. Lesion of the hip abductor mechanism

    PubMed Central

    Caviglia, Horacio; Cambiaggi, Guillermo; Vattani, Nosrat; Landro, María Eulalia; Galatro, Gustavo

    2016-01-01

    Introduction: The disruption of the abductor muscles of the hip after hip revision surgery often causes limping, pain, and instability of the implant. The purpose of our paper is to describe a mesh technique to repair hip abductor mechanism injuries after hip revision. Patients and methods: Forty-six patients with hip abductor damage after prosthetic revision were treated. Inclusion criteria were: patients presenting with prosthetic loosening, complaint of pain, and with a positive Trendelenburg sign due to deficient abductor muscle mechanisms. Thirty-one were women (67.39%) with an average age of 64 years (34–82 years). The number of previous revision surgeries was three (two to seven). The Merle d’Aubigné score and variants before and after treatment were also reported. Results: In the postoperative follow-up after hip revision with the mesh technique, the Merle d’Aubigné score improved and the Trendelenburg sign was negative in 78.3% of the patients (p < 0.001). Also, the Trendelenburg test with the knee flexed was negative in 60.9% (p < 0.001) and the stair-climbing test was negative in 60.9% of cases (p < 0.001). The gluteus medius test in the lateral position was negative in 52.2% of patients, and in the lateral position with the knee flexed it was negative in 47.8% of patients (p < 0.001). Discussion: Repair of the abductor mechanism with the mesh technique has proven effective for both partial and total lesions. PMID:27382925

  4. Weakness

    MedlinePlus

    Lack of strength; Muscle weakness ... feel weak but have no real loss of strength. This is called subjective weakness. It may be ... flu. Or, you may have a loss of strength that can be noted on a physical exam. ...

  5. Psychometric Testing of the Gordon Facial Muscle Weakness Assessment Tool

    ERIC Educational Resources Information Center

    Gordon, Shirley C.; Blum, Cynthia Ann; Parcells, Dax Andrew

    2010-01-01

    School nurses may be the first health professionals to assess the onset of facial paralysis/muscle weakness in school-age children. The purpose of this study was to test the psychometric properties of the Gordon Facial Muscle Weakness Assessment Tool (GFMWT) developed by Gordon. Data were collected in two phases. In Phase 1, 4 content experts…

  6. Permanent muscle weakness in McArdle disease.

    PubMed

    Nadaj-Pakleza, Aleksandra A; Vincitorio, Carlo M; Laforêt, Pascal; Eymard, Bruno; Dion, Elisabeth; Teijeira, Susana; Vietez, Irene; Jeanpierre, Marc; Navarro, Carmen; Stojkovic, Tanya

    2009-09-01

    McArdle disease is an autosomal recessive muscle glycogenosis. In the typical clinical presentation, only exercise-related symptoms are noted. Nevertheless, permanent weakness may occur, usually late in life. In this study we report on the clinical and genetic features of fixed muscle weakness in McArdle disease. Among the 80 McArdle patients being followed at the Institute of Myology of the Salpêtrière Hospital, 9 patients have permanent weakness. The diagnosis of McArdle disease was confirmed by muscle biopsy and genetic investigations. Two patterns of muscle weakness and wasting were noted: (1) proximal and symmetric in 5 patients; and (2) asymmetric, mimicking facioscapulohumeral dystrophy (FSHD) in 4 patients. Computerized tomography scan showed fatty infiltration in the shoulder and pelvic girdle muscles. There was no clear correlation between genotype and the severity of muscle weakness. Proximal muscle weakness appeared after the age of 40 years and affected 11% of subjects in our series of 80 McArdle patients. Among patients over 40 years of age, 37.5% had muscle weakness.

  7. The effect of abductor muscle and anterior-posterior hip contact load simulation on the in-vitro primary stability of a cementless hip stem

    PubMed Central

    2010-01-01

    Background In-vitro mechanical tests are commonly performed to assess pre-clinically the effect of implant design on the stability of hip endoprostheses. There is no standard protocol for these tests, and the forces applied vary between studies. This study examines the effect of the abductor force with and without application of the anterior-posterior hip contact force in the in-vitro assessment of cementless hip implant stability. Methods Cementless stems (VerSys Fiber Metal) were implanted in twelve composite femurs which were divided into two groups: group 1 (N = 6) was loaded with the hip contact force only, whereas group 2 (N = 6) was additionally subjected to an abductor force. Both groups were subjected to the same cranial-caudal hip contact force component, 2.3 times body weight (BW) and each specimen was subjected to three levels of anterior-posterior hip contact load: 0, -0.1 to 0.3 BW (walking), and -0.1 to 0.6 BW (stair climbing). The implant migration and micromotion relative to the femur was measured using a custom-built system comprised of 6 LVDT sensors. Results Substantially higher implant motion was observed when the anterior-posterior force was 0.6BW compared to the lower anterior-posterior load levels, particularly distally and in retroversion. The abductor load had little effect on implant motion when simulating walking, but resulted in significantly less motion than the hip contact force alone when simulating stair climbing. Conclusions The anterior-posterior component of the hip contact load has a significant effect on the axial motion of the stem relative to the bone. Inclusion of the abductor force had a stabilizing effect on the implant motion when simulating stair climbing. PMID:20576151

  8. Psychometric testing of the Gordon Facial Muscle Weakness Assessment Tool.

    PubMed

    Gordon, Shirley C; Blum, Cynthia Ann; Parcells, Dax Andrew

    2010-12-01

    School nurses may be the first health professionals to assess the onset of facial paralysis/muscle weakness in school-age children. The purpose of this study was to test the psychometric properties of the Gordon Facial Muscle Weakness Assessment Tool (GFMWT) developed by Gordon. Data were collected in two phases. In Phase 1, 4 content experts independently rated each of the 22 items on the GFMWT for content relevance. The ratings were used to generate Item and Scale Content Validity Index (CVI) scores. In Phase 2, school nurses (N = 74) attending a state conference independently rated referral urgency on a set of 10 clinical scenarios using the GFMWT. The GFMWT had an item and scale CVI of 1.0. Overall, the interrater reliability was .602 (p < .001). When used by school nurses, the GFMWT was shown to be both a reliable and a valid tool to assess facial muscle weakness in school-age children.

  9. Objective Evaluation of Muscle Strength in Infants with Hypotonia and Muscle Weakness

    ERIC Educational Resources Information Center

    Reus, Linda; van Vlimmeren, Leo A.; Staal, J. Bart; Janssen, Anjo J. W. M.; Otten, Barto J.; Pelzer, Ben J.; Nijhuis-van der Sanden, Maria W. G.

    2013-01-01

    The clinical evaluation of an infant with motor delay, muscle weakness, and/or hypotonia would improve considerably if muscle strength could be measured objectively and normal reference values were available. The authors developed a method to measure muscle strength in infants and tested 81 typically developing infants, 6-36 months of age, and 17…

  10. Red fist and muscle weakness with a rare complication

    PubMed Central

    van Groeningen, Iris; Arnoldus, Joyce; Perenboom, Roos; Voskuyl, Alexandre

    2014-01-01

    A 64-year-old man was referred to our hospital, for a second opinion, with fever, skin lesions and general muscle pain. He has been treated in another hospital with antibiotics on suspicion of erysipelas. A week later skin lesions developed on the metacarpophalangeal and proximal carpophalangeal joints of the hands and nose. His mobility was impaired due to muscle pain and muscle weakness. He also showed proximal muscle atrophy and most importantly a typical heliotrope rash in the eyes. Based on these clinical observations, the most likely diagnosis was dermatomyositis. The diagnosis was confirmed by the presence of increased serum creatine kinase levels and abnormalities in skin and muscle biopsy. Prednisone (70 mg/kg) was initiated, but after  19 days the patient developed a Pneumocystis jiroveci pneumonia. He died of respiratory failure a few days later. PMID:24557476

  11. Neurophysiological correlates of aging-related muscle weakness

    PubMed Central

    Cunningham, David A.; Bonnett, Corin; Gohar, Dina; Bayram, Mehmed; Wyant, Alexandria; Varnerin, Nicole; Mamone, Bernadett; Siemionow, Vlodek; Hou, Juliet; Machado, Andre; Yue, Guang H.

    2013-01-01

    Muscle weakness associated with aging implicates central neural degeneration. However, role of the primary motor cortex (M1) is poorly understood, despite evidence that gains in strength in younger adults are associated with its adaptations. We investigated whether weakness of biceps brachii in aging analogously relates to processes in M1. We enrolled 20 young (22.6 ± 0.87 yr) and 28 old (74.79 ± 1.37 yr) right-handed participants. Using transcranial magnetic stimulation, representation of biceps in M1 was identified. We examined the effect of age and sex on strength of left elbow flexion, voluntary activation of biceps, corticospinal excitability and output, and short-interval intracortical and interhemispheric inhibition. Interhemispheric inhibition was significantly exaggerated in the old (P = 0.047), while strength tended to be lower (P = 0.075). Overall, women were weaker (P < 0.001). Processes of M1 related to strength or voluntary activation of biceps, but only in older adults. Corticospinal excitability was lower in weaker individuals (r = 0.38), and corticospinal output, intracortical inhibition and interhemispheric inhibition were reduced too in individuals who poorly activated biceps (r = 0.43, 0.54 and 0.38). Lower intracortical inhibition may reflect compensation for reduced corticospinal excitability, allowing weaker older adults to spread activity in M1 to recruit synergists and attempt to sustain motor output. Exaggerated interhemispheric inhibition, however, conflicts with previous evidence, potentially related to greater callosal damage in our older sample, our choice of proximal vs. distal muscle and differing influence of measurement of inhibition in rest vs. active states of muscle. Overall, age-specific relation of M1 to strength and muscle activation emphasizes that its adaptations only emerge when necessitated, as in a weakening neuromuscular system in aging. PMID:24027104

  12. Distally Based Abductor Hallucis Adipomuscular Flap for Forefoot Plantar Reconstruction.

    PubMed

    Lee, Sanglim; Kim, Min Bom; Lee, Young Ho; Baek, Jeong Kook; Baek, Goo Hyun

    2015-09-01

    Soft tissue and bone defects of the lower leg, ankle, and heel region often require coverage by local or distant flaps. The authors successfully used the distally based adipomuscular abductor hallucis flap for the treatment of 7 patients with soft tissue defect on the plantar forefoot after diabetic ulcer (n = 2), excision of melanoma at the medial forefoot (n = 3), and posttraumatic defects of the plantar forefoot (n = 2). The size of the defects ranged from 6 to 36 cm. All defects were covered successfully without major complications. The distally based adipomuscular flap from the abductor hallucis muscle provides a reliable coverage for small and moderate defects of the plantar and medial forefoot. This flap is often preferable to the use of free flaps because the surgery is rapidly performed and does not require microsurgical expertise.

  13. Abductor Reconstruction with Gluteus Maximus Transfer in Primary Abductor Deficiency during Total Hip Arthroplasty

    PubMed Central

    Jang, Se Ang; Byun, Young Soo; Gu, Tae Hoe

    2016-01-01

    Abductor deficiency in native hip joint may cause severe limping and pain. It is more serious situation in case of arthroplasty due to instability and recurrent dislocation. Well-known causes of abductor deficiency are repeated surgery, chronic trochanteric bursitis, superior gluteal nerve injury, failure of repair of abductor tendon insertion to the greater trochanter. Author had experienced primary abductor deficiency during total hip replacement and treated successfully with the transfer of gluteus maximus. We'd like to introduce the operation technique with the review of literature. PMID:27777922

  14. [Iliopsoas muscle syndrome. Functional disorders: shortening, spasm and weakness of a structurally unchanged muscle].

    PubMed

    Grgić, Vjekoslav

    2009-01-01

    Functional (non-organic) disorders of the iliopsoas muscle (IPM), i.e. the shortening, spasm and weakness of the structurally unchanged IPM, can be manifested as abdominal and/or pelvic pain, pain in areas of the thoracolumbar (ThL) and lumbosacral (LS) spine, sacroiliac (SI) joint, hip, groin and anterior thigh on the side of the affected muscle as well as gait disturbances (iliopsoas muscle syndrome). By clinical examination of the IPM, including the transabdominal palpation, stretch and strength tests, pathological masses, shortening, painful spasm, weakness and tendon tenderness of that muscle can be diagnosed. The IPM is, like other postural muscles, inclined to shortening. The weakness of the IPM can be a consequence of the lesion of the lumbar plexus or femoral nerve that innervate the IPM, as well as a consequence of certain organic diseases of the IPM. Painful stimuli coming from somatic and visceral structures that are innervated from Th12-L4 nerve roots, from which the IPM segmental innervation also originates, can cause a reflex spasm of the IPM. A painful spasm of the IPM caused by disorders of the ThL and LS spine, SI and hip joint, can mimic diseases of the abdominal and pelvic organs. In the differential diagnosis of the IPM painful spasm, organic diseases of that muscle should be considered foremost (abscess, hematoma, tumor, metastase), as they can result in spasm, and the diseases of the abdominal and pelvic organs that can cause an IPM reflex spasm. The IPM functional disorders, which are not rare, are often overlooked during a clinical examination of a patient. Reasons for overlooking these disorders are: 1) a nonspecific and variable clinical picture presenting the IPM functional disorders, 2) the IPM functional disorders are a neglected source of pain, 3) the inaccessibility of the IPM for inspection, 4) the lack of knowledge of the IPM examination techniques and 5) the IPM functional disorders cannot be discovered by radiological

  15. Muscle weakness in respiratory and peripheral skeletal muscles in a mouse model for nebulin-based nemaline myopathy.

    PubMed

    Joureau, Barbara; de Winter, Josine M; Stam, Kelly; Granzier, Henk; Ottenheijm, Coen A C

    2017-01-01

    Nemaline myopathy is among the most common non-dystrophic congenital myopathies, and is characterized by the presence of nemaline rods in skeletal muscles fibers, general muscle weakness, and hypotonia. Although respiratory failure is the main cause of death in nemaline myopathy, only little is known regarding the contractile strength of the diaphragm, the main muscle of inspiration. To investigate diaphragm contractility, in the present study we took advantage of a mouse model for nebulin-based nemaline myopathy that we recently developed. In this mouse model, exon 55 of Neb is deleted (Neb(ΔExon55)), a mutation frequently found in patients. Diaphragm contractility was determined in permeabilized muscle fibers and was compared to the contractility of permeabilized fibers from three peripheral skeletal muscles: soleus, extensor digitorum longus, and gastrocnemius. The force generating capacity of diaphragm muscle fibers of Neb(ΔExon55) mice was reduced to 25% of wildtype levels, indicating severe contractile weakness. The contractile weakness of diaphragm fibers was more pronounced than that observed in soleus muscle, but not more pronounced than that observed in extensor digitorum longus and gastrocnemius muscles. The reduced muscle contractility was at least partly caused by changes in cross-bridge cycling kinetics which reduced the number of bound cross-bridges. The severe diaphragm weakness likely contributes to the development of respiratory failure in Neb(ΔExon55) mice and might explain their early, postnatal death.

  16. Clinical strategies for addressing muscle weakness following knee injury.

    PubMed

    Pietrosimone, Brian; Blackburn, J Troy; Harkey, Matthew S; Luc, Brittney A; Pamukoff, Derek N; Hart, Joe M

    2015-04-01

    Muscle strength is a determinate of physical function and increasing muscle strength is an important clinical goal for patients with knee injury. This article discusses the emerging evidence regarding a novel rehabilitation strategy that uses disinhibitory modalities to increase neuromuscular activation in conjunction with traditional muscle strengthening for the purpose of maximizing strength gains following acute knee injury or surgery and in patients with knee osteoarthritis. The use of disinhibitory modalities and specific types of neuromuscular training for clinically maximizing strength are discussed.

  17. Progressive Muscle Atrophy and Weakness After Treatment by Mantle Field Radiotherapy in Hodgkin Lymphoma Survivors

    SciTech Connect

    Leeuwen-Segarceanu, Elena M. van; Dorresteijn, Lucille D.A.; Pillen, Sigrid; Biesma, Douwe H.; Vogels, Oscar J.M.; Alfen, Nens van

    2012-02-01

    Purpose: To describe the damage to the muscles and propose a pathophysiologic mechanism for muscle atrophy and weakness after mantle field radiotherapy in Hodgkin lymphoma (HL) survivors. Methods and Materials: We examined 12 patients treated by mantle field radiotherapy between 1969 and 1998. Besides evaluation of their symptoms, the following tests were performed: dynamometry; ultrasound of the sternocleidomastoid, biceps, and antebrachial flexor muscles; and needle electromyography of the neck, deltoid, and ultrasonographically affected arm muscles. Results: Ten patients (83%) experienced neck complaints, mostly pain and muscle weakness. On clinical examination, neck flexors were more often affected than neck extensors. On ultrasound, the sternocleidomastoid was severely atrophic in 8 patients, but abnormal echo intensity was seen in only 3 patients. Electromyography of the neck muscles showed mostly myogenic changes, whereas the deltoid, biceps, and antebrachial flexor muscles seemed to have mostly neurogenic damage. Conclusions: Many patients previously treated by mantle field radiotherapy develop severe atrophy and weakness of the neck muscles. Neck muscles within the radiation field show mostly myogenic damage, and muscles outside the mantle field show mostly neurogenic damage. The discrepancy between echo intensity and atrophy suggests that muscle damage is most likely caused by an extrinsic factor such as progressive microvascular fibrosis. This is also presumed to cause damage to nerves within the radiated field, resulting in neurogenic damage of the deltoid and arm muscles.

  18. A case of Creutzfeldt-Jacob disease with bilateral vocal fold abductor paralysis.

    PubMed

    Li, Lishu; Saigusa, Hideto; Nagayama, Hiroshi; Nakamura, Tsuyoshi; Aino, Iichirou; Komachi, Taro; Yamaguchi, Satoshi

    2009-09-01

    Bilateral vocal fold abductor paralysis was seen in a patient with Creutzfeldt-Jacob disease. After tracheotomy, the patient showed disappearance of reduced oxygen saturation with high-pitched inspiratory stridor and pulling phenomenon of the supraclavicular region and larynx. Electromyographic examinations of the intrinsic laryngeal muscles, including the thyroarytenoid and posterior cricoarytenoid muscles, demonstrated that there was no apparent action potential in those muscles during spontaneous respiratory movements, and there was no abnormal potential for those muscles at rest. By pushing the infrasternal region of the patient on the expiration, normal motor unit action potential could be seen in the posterior cricoarytenoid muscle on the next inspiration. Based on those findings, we concluded that bilateral vocal fold abductor paralysis in this case of Creutzfeldt-Jacob disease was not induced by disorders of the degeneration of motor nucleus in the ambiguus as in multiple system atrophy, but by a disorder of the upper motor neuron.

  19. Impaired mitochondrial respiration and decreased fatigue resistance followed by severe muscle weakness in skeletal muscle of mitochondrial DNA mutator mice.

    PubMed

    Yamada, Takashi; Ivarsson, Niklas; Hernández, Andrés; Fahlström, Andreas; Cheng, Arthur J; Zhang, Shi-Jin; Bruton, Joseph D; Ulfhake, Brun; Westerblad, Håkan

    2012-12-01

    Mitochondrial dysfunction can drastically impair muscle function, with weakness and exercise intolerance as key symptoms. Here we examine the time course of development of muscle dysfunction in a mouse model of premature ageing induced by defective proofreading function of mitochondrial DNA (mtDNA) polymerase (mtDNA mutator mouse). Isolated fast-twitch muscles and single muscle fibres from young (3-5 months) and end-stage (11 months) mtDNA mutator mice were compared to age-matched control mice. Force and free myoplasmic [Ca(2+)] ([Ca(2+)](i)) were measured under resting conditions and during fatigue induced by repeated tetani. Muscles of young mtDNA mutator mice displayed no weakness in the rested state, but had lower force and [Ca(2+)](i) than control mice during induction of fatigue. Muscles of young mtDNA mutator mice showed decreased activities of citrate synthase and β-hydroxyacyl-coenzyme A dehydrogenase, reduced expression of cytochrome c oxidase, and decreased expression of triggers of mitochondrial biogenesis (PGC-1α, PPARα, AMPK). Muscles from end-stage mtDNA mutator mice showed weakness under resting conditions with markedly decreased tetanic [Ca(2+)](i), force per cross-sectional area and protein expression of the sarcoplasmic reticulum Ca(2+) pump (SERCA1). In conclusion, fast-twitch muscles of prematurely ageing mtDNA mutator mice display a sequence of deleterious mitochondrial-to-nucleus signalling with an initial decrease in oxidative capacity, which was not counteracted by activation of signalling to increase mitochondrial biogenesis. This was followed by severe muscle weakness in the end stage. These results have implication for normal ageing and suggest that decreased mitochondrial oxidative capacity due to a sedentary lifestyle may predispose towards muscle weakness developing later in life.

  20. Practical Recommendations for Diagnosis and Management of Respiratory Muscle Weakness in Late-Onset Pompe Disease.

    PubMed

    Boentert, Matthias; Prigent, Hélène; Várdi, Katalin; Jones, Harrison N; Mellies, Uwe; Simonds, Anita K; Wenninger, Stephan; Barrot Cortés, Emilia; Confalonieri, Marco

    2016-10-17

    Pompe disease is an autosomal-recessive lysosomal storage disorder characterized by progressive myopathy with proximal muscle weakness, respiratory muscle dysfunction, and cardiomyopathy (in infants only). In patients with juvenile or adult disease onset, respiratory muscle weakness may decline more rapidly than overall neurological disability. Sleep-disordered breathing, daytime hypercapnia, and the need for nocturnal ventilation eventually evolve in most patients. Additionally, respiratory muscle weakness leads to decreased cough and impaired airway clearance, increasing the risk of acute respiratory illness. Progressive respiratory muscle weakness is a major cause of morbidity and mortality in late-onset Pompe disease even if enzyme replacement therapy has been established. Practical knowledge of how to detect, monitor and manage respiratory muscle involvement is crucial for optimal patient care. A multidisciplinary approach combining the expertise of neurologists, pulmonologists, and intensive care specialists is needed. Based on the authors' own experience in over 200 patients, this article conveys expert recommendations for the diagnosis and management of respiratory muscle weakness and its sequelae in late-onset Pompe disease.

  1. Practical Recommendations for Diagnosis and Management of Respiratory Muscle Weakness in Late-Onset Pompe Disease

    PubMed Central

    Boentert, Matthias; Prigent, Hélène; Várdi, Katalin; Jones, Harrison N.; Mellies, Uwe; Simonds, Anita K.; Wenninger, Stephan; Barrot Cortés, Emilia; Confalonieri, Marco

    2016-01-01

    Pompe disease is an autosomal-recessive lysosomal storage disorder characterized by progressive myopathy with proximal muscle weakness, respiratory muscle dysfunction, and cardiomyopathy (in infants only). In patients with juvenile or adult disease onset, respiratory muscle weakness may decline more rapidly than overall neurological disability. Sleep-disordered breathing, daytime hypercapnia, and the need for nocturnal ventilation eventually evolve in most patients. Additionally, respiratory muscle weakness leads to decreased cough and impaired airway clearance, increasing the risk of acute respiratory illness. Progressive respiratory muscle weakness is a major cause of morbidity and mortality in late-onset Pompe disease even if enzyme replacement therapy has been established. Practical knowledge of how to detect, monitor and manage respiratory muscle involvement is crucial for optimal patient care. A multidisciplinary approach combining the expertise of neurologists, pulmonologists, and intensive care specialists is needed. Based on the authors’ own experience in over 200 patients, this article conveys expert recommendations for the diagnosis and management of respiratory muscle weakness and its sequelae in late-onset Pompe disease. PMID:27763517

  2. Muscle Weakness and Speech in Oculopharyngeal Muscular Dystrophy

    ERIC Educational Resources Information Center

    Neel, Amy T.; Palmer, Phyllis M.; Sprouls, Gwyneth; Morrison, Leslie

    2015-01-01

    Purpose: We documented speech and voice characteristics associated with oculopharyngeal muscular dystrophy (OPMD). Although it is a rare disease, OPMD offers the opportunity to study the impact of myopathic weakness on speech production in the absence of neurologic deficits in a relatively homogeneous group of speakers. Methods: Twelve individuals…

  3. Twitch mouth pressure for detecting respiratory muscle weakness in suspicion of neuromuscular disorder.

    PubMed

    Santos, Dante Brasil; Desmarais, Gilbert; Falaize, Line; Ogna, Adam; Cognet, Sandrine; Louis, Bruno; Orlikowski, David; Prigent, Hélène; Lofaso, Frédéric

    2017-02-02

    Twitch mouth pressure using magnetic stimulation of the phrenic nerves and an automated inspiratory trigger is a noninvasive, non-volitional assessment of diaphragmatic strength. Our aims were to validate this method in patients with suspected neuromuscular disease, to determine the best inspiratory-trigger pressure threshold, and to evaluate whether twitch mouth pressure decreased the overdiagnosis of muscle weakness frequently observed with noninvasive volitional tests. Maximal inspiratory pressure, sniff nasal pressure, and twitch mouth pressure were measured in 112 patients with restrictive disease and suspected neuromuscular disorder. Esophageal and transdiaphragmatic pressures were measured in 64 of these patients to confirm or infirm inspiratory muscle weakness. Magnetic stimulation was triggered by inspiratory pressures of -1 and -5 cmH2O. The -5 cmH2O trigger produced the best correlation between twitch mouth pressure and twitch esophageal pressure (R(2) = 0.86; P <0.0001). The best association of noninvasive tests to predict inspiratory muscle weakness was sniff nasal pressure and twitch mouth pressure. Below-normal maximal inspiratory pressure and sniff nasal pressure values suggesting inspiratory muscle weakness were found in 63/112 patients. Only 52 of these 63 patients also had abnormal twitch mouth pressure. In conclusion twitch mouth pressure measurement is a simple, noninvasive, nonvolitional technique which may help to select patients with suspected neuromuscular disorder for invasive inspiratory-muscle investigation.

  4. Sporadic Inclusion Body Myositis Manifesting as Isolated Muscle Weakness of the Finger Flexors Three Years after Disease Onset

    PubMed Central

    Suwa, Yuichi; Suzuki, Naoki; Soga, Temma; Harada, Ryuhei; Shibui, Aya; Kuroda, Hiroshi; Izumi, Rumiko; Tateyama, Maki; Nakashima, Ichiro; Sonoo, Masahiro; Aoki, Masashi

    2016-01-01

    Sporadic inclusion body myositis (sIBM) is a chronic progressive myopathy characterized by muscle weakness of both the quadriceps femoris and finger flexors. We herein present the case of a typical male patient with sIBM, which manifested as the isolated weakness of the finger flexors three years after the disease onset. We have identified several patients with sIBM in our cohort with muscle weakness of the flexors but not the quadriceps femoris. Examination of the flexor digitorum profundus muscle is important for the early and proper diagnosis of sIBM, even if a patient only presents with isolated finger flexor muscle weakness. PMID:27904121

  5. Diaphragm Muscle Fiber Weakness and Ubiquitin–Proteasome Activation in Critically Ill Patients

    PubMed Central

    Hooijman, Pleuni E.; Beishuizen, Albertus; Witt, Christian C.; de Waard, Monique C.; Girbes, Armand R. J.; Spoelstra-de Man, Angelique M. E.; Niessen, Hans W. M.; Manders, Emmy; van Hees, Hieronymus W. H.; van den Brom, Charissa E.; Silderhuis, Vera; Lawlor, Michael W.; Labeit, Siegfried; Stienen, Ger J. M.; Hartemink, Koen J.; Paul, Marinus A.; Heunks, Leo M. A.

    2015-01-01

    Rationale: The clinical significance of diaphragm weakness in critically ill patients is evident: it prolongs ventilator dependency, and increases morbidity and duration of hospital stay. To date, the nature of diaphragm weakness and its underlying pathophysiologic mechanisms are poorly understood. Objectives: We hypothesized that diaphragm muscle fibers of mechanically ventilated critically ill patients display atrophy and contractile weakness, and that the ubiquitin–proteasome pathway is activated in the diaphragm. Methods: We obtained diaphragm muscle biopsies from 22 critically ill patients who received mechanical ventilation before surgery and compared these with biopsies obtained from patients during thoracic surgery for resection of a suspected early lung malignancy (control subjects). In a proof-of-concept study in a muscle-specific ring finger protein-1 (MuRF-1) knockout mouse model, we evaluated the role of the ubiquitin–proteasome pathway in the development of contractile weakness during mechanical ventilation. Measurements and Main Results: Both slow- and fast-twitch diaphragm muscle fibers of critically ill patients had approximately 25% smaller cross-sectional area, and had contractile force reduced by half or more. Markers of the ubiquitin–proteasome pathway were significantly up-regulated in the diaphragm of critically ill patients. Finally, MuRF-1 knockout mice were protected against the development of diaphragm contractile weakness during mechanical ventilation. Conclusions: These findings show that diaphragm muscle fibers of critically ill patients display atrophy and severe contractile weakness, and in the diaphragm of critically ill patients the ubiquitin–proteasome pathway is activated. This study provides rationale for the development of treatment strategies that target the contractility of diaphragm fibers to facilitate weaning. PMID:25760684

  6. Correcting myogenic ptosis accompanying extraocular muscle weakness: The "Bobby Pin" procedure.

    PubMed

    Vemuri, Swapna; Christianson, Murray D; Demirci, Hakan

    2016-10-01

    This article evaluates the "Bobby Pin" procedure in the correction of myogenic ptosis accompanying extraocular muscle weakness. We retrospectively reviewed 26 eyelids of 13 patients who underwent "Bobby Pin" procedure for myogenic ptosis accompanying extraocular muscle weakness. We evaluated the patients' clinical features such as age, etiology of ptosis, symptoms, standard ptosis measurements, associated systemic diseases, additional ophthalmic conditions, complications, and recurrence. Etiology of myogenic ptosis and extraocular muscle weakness was oculopharyngeal dystrophy in 4 (31%) patients, chronic progressive external ophthalmoplegia in 4 (31%) patients, myotonic dystrophy in 2 (23%) patients, and idiopathic in 3 (15%) patients. The mean levator function was approximately 5 mm pre- and post-operatively (range 1 to 12 mm). The mean margin-to-reflex distance 1 increased from -1.1 mm (below the light reflex) pre-operatively to +0.4 mm (above the light reflex) post-operatively. After a mean follow-up of 40 months, only 1 (8%) patient experienced ptosis recurrence. Upper eyelids were symmetric in both contour and height in all patients. Mild superficial keratopathy involving less than 10% of cornea was observed in 4 (31%) patients. The "Bobby Pin" procedure is an effective and long-lasting treatment option for correcting acquired ptosis accompanying extraocular muscle weakness. The procedure is safe, simple, easily learned, time- and cost-effective, and does not require any expensive equipment.

  7. Fast skeletal muscle troponin activation increases force of mouse fast skeletal muscle and ameliorates weakness due to nebulin-deficiency.

    PubMed

    Lee, Eun-Jeong; De Winter, Josine M; Buck, Danielle; Jasper, Jeffrey R; Malik, Fady I; Labeit, Siegfried; Ottenheijm, Coen A; Granzier, Henk

    2013-01-01

    The effect of the fast skeletal muscle troponin activator, CK-2066260, on calcium-induced force development was studied in skinned fast skeletal muscle fibers from wildtype (WT) and nebulin deficient (NEB KO) mice. Nebulin is a sarcomeric protein that when absent (NEB KO mouse) or present at low levels (nemaline myopathy (NM) patients with NEB mutations) causes muscle weakness. We studied the effect of fast skeletal troponin activation on WT muscle and tested whether it might be a therapeutic mechanism to increase muscle strength in nebulin deficient muscle. We measured tension-pCa relations with and without added CK-2066260. Maximal active tension in NEB KO tibialis cranialis fibers in the absence of CK-2066260 was ∼60% less than in WT fibers, consistent with earlier work. CK-2066260 shifted the tension-calcium relationship leftwards, with the largest relative increase (up to 8-fold) at low to intermediate calcium levels. This was a general effect that was present in both WT and NEB KO fiber bundles. At pCa levels above ∼6.0 (i.e., calcium concentrations <1 µM), CK-2066260 increased tension of NEB KO fibers to beyond that of WT fibers. Crossbridge cycling kinetics were studied by measuring k(tr) (rate constant of force redevelopment following a rapid shortening/restretch). CK-2066260 greatly increased k(tr) at submaximal activation levels in both WT and NEB KO fiber bundles. We also studied the sarcomere length (SL) dependence of the CK-2066260 effect (SL 2.1 µm and 2.6 µm) and found that in the NEB KO fibers, CK-2066260 had a larger effect on calcium sensitivity at the long SL. We conclude that fast skeletal muscle troponin activation increases force at submaximal activation in both wildtype and NEB KO fiber bundles and, importantly, that this troponin activation is a potential therapeutic mechanism for increasing force in NM and other skeletal muscle diseases with loss of muscle strength.

  8. Simvastatin reduces fibrosis and protects against muscle weakness after massive rotator cuff tear

    PubMed Central

    Davis, Max E; Korn, Michael A; Gumucio, Jonathan P; Harning, Julie A; Saripalli, Anjali L; Bedi, Asheesh; Mendias, Christopher L

    2014-01-01

    Background Chronic rotator cuff tears are a common source of shoulder pain and disability, and patients with chronic cuff tears often have substantial weakness, fibrosis, inflammation and fat accumulation. Identifying therapies to prevent the development of these pathologies will likely have a positive impact on clinical outcomes. Simvastatin is a drug with demonstrated anti-inflammatory and anti-fibrotic effects in many tissues, but had not previously been studied in the context of rotator cuff tears. We hypothesized that following the induction of a massive supraspinatus tear, simvastatin would protect muscles from a loss of force production and fibrosis. Methods We measured changes in muscle fiber contractility, histology and biochemical markers of fibrosis and fatty infiltration in rats that received a full-thickness supraspinatus tear and were treated with either carrier alone or simvastatin. Results Compared to vehicle treated controls, simvastatin did not have an appreciable effect on muscle fiber size, but treatment did increase muscle fiber specific force by 20%. Simvastatin also reduced collagen accumulation by 50%, but did not effect triglyceride content of muscles. Several favorable changes in the expression of genes and other markers of inflammation, fibrosis and regeneration were also observed. Conclusions Simvastatin partially protected muscles from the weakness that occurs as a result of chronic rotator cuff tear. Fibrosis was also markedly reduced in simvastatin treated animals. While further studies are necessary, statin medication could potentially help to improve outcomes for patients with rotator cuff tears. PMID:25213828

  9. Epigenetic changes as a common trigger of muscle weakness in congenital myopathies.

    PubMed

    Rokach, Ori; Sekulic-Jablanovic, Marijana; Voermans, Nicol; Wilmshurst, Jo; Pillay, Komala; Heytens, Luc; Zhou, Haiyan; Muntoni, Francesco; Gautel, Mathias; Nevo, Yoram; Mitrani-Rosenbaum, Stella; Attali, Ruben; Finotti, Alessia; Gambari, Roberto; Mosca, Barbara; Jungbluth, Heinz; Zorzato, Francesco; Treves, Susan

    2015-08-15

    Congenital myopathies are genetically and clinically heterogeneous conditions causing severe muscle weakness, and mutations in the ryanodine receptor gene (RYR1) represent the most frequent cause of these conditions. A common feature of diseases caused by recessive RYR1 mutations is a decrease of ryanodine receptor 1 protein content in muscle. The aim of the present investigation was to gain mechanistic insight into the causes of this reduced ryanodine receptor 1. We found that muscle biopsies of patients with recessive RYR1 mutations exhibit decreased expression of muscle-specific microRNAs, increased DNA methylation and increased expression of class II histone deacetylases. Transgenic mouse muscle fibres over-expressing HDAC-4/HDAC-5 exhibited decreased expression of RYR1 and of muscle-specific miRNAs, whereas acute knock-down of RYR1 in mouse muscle fibres by siRNA caused up-regulation of HDAC-4/HDAC-5. Intriguingly, increased class II HDAC expression and decreased ryanodine receptor protein and miRNAs expression were also observed in muscles of patients with nemaline myopathy, another congenital neuromuscular disorder. Our results indicate that a common pathophysiological pathway caused by epigenetic changes is activated in some forms of congenital neuromuscular disorders.

  10. IgM MGUS anti-MAG neuropathy with predominant muscle weakness and extensive muscle atrophy.

    PubMed

    Kawagashira, Yuichi; Kondo, Naohide; Atsuta, Naoki; Iijima, Masahiro; Koike, Haruki; Katsuno, Masahisa; Tanaka, Fumiaki; Kusunoki, Susumu; Sobue, Gen

    2010-09-01

    We report a patient with anti-myelin-associated glycoprotein (MAG) neuropathy, predominantly exhibiting severe motor symptoms, accompanied by extensive muscle atrophy mimicking Charcot-Marie-Tooth disease. Nerve conduction studies revealed mild retardation of motor conduction velocities and significant prolongation of distal latency. Sural nerve biopsy revealed widely spaced myelin and positive staining of myelinated fibers with an IgM antibody. Predominant motor symptoms with muscle atrophy can be one of the clinical manifestations of anti-MAG neuropathy.

  11. Weakness in mouse masticatory muscles by repetitive contractions with forced lengthening.

    PubMed

    Hutchins, M O; Skjonsby, H S; Brazeau, G A; Parikh, U K; Jenkins, R M

    1995-02-01

    The etiology of myofascial tenderness and pain of masticatory muscles in humans is difficult to understand. Parafunctional oral habits such as tooth grinding or vigorous chewing are thought to be factors. The objective of this study was to determine if masticatory muscles are susceptible to weakness and injury induced by repetitive, dynamic, forced-lengthening contractions. Results would support the hypothesis that contraction-induced injuries could occur in hyperactive masticatory muscles of humans in response to parafunctional oral habits. Mice were anesthetized and randomly assigned to three groups: non-treated controls, treated by repetitive passive jaw opening, or treated by repetitive isometric tetanic contractions with lengthening by jaw opening. In each treatment group, masticatory muscle injury was evaluated by contractile tension, plasma creatine kinase, and muscle glycogen. Contractile tension was determined at different stimulation frequencies and was significantly decreased 5 min, 4 h, and 72 h after repetitive contraction/lengthening. Plasma creatine kinase was significantly elevated at 4 but not at 72 h post-treatment in mice subjected to repetitive contraction/lengthening. Masticatory muscle glycogen was not significantly different in any groups at 4 or 72 h post-treatment. These results indicate that contraction injuries can be induced in masticatory muscle of mice by forced lengthening contractions which simulate eccentric contractions.

  12. A decline in PABPN1 induces progressive muscle weakness in oculopharyngeal muscle dystrophy and in muscle aging.

    PubMed

    Anvar, Seyed Yahya; Raz, Yotam; Verway, Nisha; van der Sluijs, Barbara; Venema, Andrea; Goeman, Jelle J; Vissing, John; van der Maarel, Silvère M; 't Hoen, Peter A C; van Engelen, Baziel G M; Raz, Vered

    2013-06-01

    Oculopharyngeal muscular dystrophy (OPMD) is caused by trinucleotide repeat expansion mutations in Poly(A) binding protein 1 (PABPN1). PABPN1 is a regulator of mRNA stability and is ubiquitously expressed. Here we investigated how symptoms in OPMD initiate only at midlife and why a subset of skeletal muscles is predominantly affected. Genome-wide RNA expression profiles from Vastus lateralis muscles human carriers of expanded-PABPN1 at pre-symptomatic and symptomatic stages were compared with healthy controls. Major expression changes were found to be associated with age rather than with expression of expanded-PABPN1, instead transcriptomes of OPMD and elderly muscles were significantly similar (P<0.05). Using k-means clustering we identified age-dependent trends in both OPMD and controls, but trends were often accelerated in OPMD. We report an age-regulated decline in PABPN1 levels in Vastus lateralis muscles from the fifth decade. In concurrence with severe muscle degeneration in OPMD, the decline in PABPN1 accelerated in OPMD and was specific to skeletal muscles. Reduced PABPN1 levels (30% to 60%) in muscle cells induced myogenic defects and morphological signatures of cellular aging in proportion to PABPN1 expression levels. We suggest that PABPN1 levels regulate muscle cell aging and OPMD represents an accelerated muscle aging disorder.

  13. Acute Onset Significant Muscle Weakness in a Patient Awaiting Liver Transplantation: Look for Statins.

    PubMed

    Choudhary, Narendra S; Saigal, Sanjiv; Saraf, Neeraj; Soin, Arvinder S

    2017-03-01

    Statins are commonly used drugs in patients with liver and cardiac disease. Statin-induced severe myopathy is a very uncommon presentation and rhabdomyolysis may occur in extreme cases which leads to renal failure. Patients with comorbidities like diabetes, hypothyroidism, and liver disease have higher chances of development of statin-induced myopathy. We describe a case of Child's C cirrhosis wherein the patient had acute onset significant muscle weakness and improved on statin discontinuation.

  14. Effect of pattern and severity of respiratory muscle weakness on carbon monoxide gas transfer and lung volumes.

    PubMed

    Hart, N; Cramer, D; Ward, S P; Nickol, A H; Moxham, J; Polkey, M I; Pride, N B

    2002-10-01

    In clinical practice, an elevated carbon monoxide (CO) transfer coefficient (KCO) and restrictive ventilatory defect are taken as features of respiratory muscle weakness (RMW). However, the authors hypothesised that both pattern and severity of RMW effect gas transfer and lung volumes. Measurements of CO transfer and lung volumes were performed in patients with isolated diaphragm weakness (n=10), inspiratory muscle weakness (n=12), combined inspiratory and expiratory muscle weakness (n=5) and healthy controls (n=6). Patients with diaphragm weakness and inspiratory muscle weakness had reduced total lung capacity (TLC) (83.6% predicted and 68.9% pred, respectively), functional residual capacity (FRC) (83.9% pred and 83.6% pred) and transfer factor of the lung for CO (TL,CO) (86.2% pred and 66.2% pred) with increased KCO (114.1% pred and 130.2% pred). Patients with combined inspiratory and expiratory muscle weakness had reduced TLC (80.9% pred) but increased FRC (109.9% pred) and RV (157.4% pred) with decreased TL,CO (58.0% pred) and KCO (85.5% pred). In patients with diaphragm weakness, the increase in carbon monoxide transfer coefficient was similar to that of normal subjects when alveolar volume was reduced. However, the increase in carbon monoxide transfer coefficient in inspiratory muscle weakness was often less than expected, while in combined inspiratory and expiratory muscle weakness, the carbon monoxide transfer coefficient was normal/reduced despite further reductions in alveolar volume, which may indicate subtle abnormalities of the lung parenchyma or pulmonary vasculature. Thus, this study demonstrates the limitations of using carbon monoxide transfer coefficient in the diagnosis of respiratory muscle weakness, particularly if no account is taken of the alveolar volume at which the carbon monoxide transfer coefficient is made.

  15. Motor units in a skeletal muscle of neonatal rat: mechanical properties and weak neuromuscular transmission.

    PubMed Central

    Jones, S P; Ridge, R M

    1987-01-01

    1. Isometric twitch and tetanic tensions were recorded from whole muscles and single motor units in isolated fourth deep lumbrical muscles from neonatal rats (most at 3-5 days old) and from older rats of various ages. 2. Whole-muscle time to peak contraction reduced from about 120 ms at birth to about 20-25 ms at 20 days and older. 3. The number of motor units in the muscle was constant with age (eleven on average) and there was no significant branching of motor axons below the common peroneal nerve branching point in the thigh. 4. In the 3-5 days age range, mean twitch:tetanus ratio for whole muscles was 0.299 and for single units was 0.177. As a consequence, mean motor unit size (as a percentage of whole-muscle tension) was greater for tetani (29.7%) than for twitches (19.9%). This was not the case in muscles from animals 22 days or older. Evidence is given that the cause of this is low junctional efficacy in some neuromuscular junctions in neonatal muscle. Intracellular recordings supported this view. 5. The relationships of motor-unit size to the contraction time, to the ratio of contraction time:half-relaxation time, and to fatigue index are given. There was no indication of clear segregation of motor units into more than one population, but it is concluded that small motor units are more likely to contain a higher proportion of slowly contracting, fatigue-resistant fibres than large units. 6. The level of overlap by axons in the lateral plantar nerve onto muscle fibres in a single sural nerve motor unit was greater in tetani than in twitches. The results indicate that the distribution of weak and strong inputs was not random, but that there was a tendency for one strong input to accompany a number of weak inputs (on average about two) on each muscle fibre. 7. Intracellular recording indicates that about 12% of fibres at 3-5 days may be electrically coupled. PMID:2824760

  16. Correlation between distribution of muscle weakness, electrophysiological findings and CTG expansion in myotonic dystrophy.

    PubMed

    Khoshbakht, Roya; Soltanzadeh, Akbar; Zamani, Babak; Abdi, Siyamak; Gharagozli, Kourosh; Kahrizi, Kimia; Khoshbakht, Rahem; Nafissi, Shahriar

    2014-07-01

    Myotonic dystrophy type 1 (DM-1) is a multi-system disorder affecting the muscles, brain, cardiovascular system, endocrine system, eyes and skin. Diagnosis is made by clinical, electrodiagnostic and genetic studies. This study aimed to determine the correlation between CTG expansion and distribution of muscle weakness and clinical and electrophysiological findings. Genetically confirmed DM-1 patients presenting to Shariati Hospital between 2005 and 2011 were included in this study. Clinical, electrodiagnostic and genetic testing was performed and the correlation between CTG expansion and distribution of muscle weakness and clinical and electromyographic findings was studied. Thirty-three genetically confirmed DM-1 patients were enrolled. Myotonia, bifacial weakness and distal upper limb weakness were seen in all patients. Diabetes mellitus was found in one patient (3%), cardiac disturbance in eight (24.2%), cataracts in eight (24.2%), hypogonadism in five (15.2%), frontal baldness in 13 (39.4%), temporalis wasting in 14 (42.4%), temporomandibular joint disorder in seven (21.2%) and mental retardation in eight (24.2%). The mean number of CTG repeats, measured by Southern blot, was 8780 (range 500-15,833). A negative correlation was found between CTG expansion and age of onset. Temporalis wasting and mental retardation were positively correlated with CTG expansion. No relationship was found between weakness distribution, electromyographic findings, other systemic features and CTG expansion. In this study of DM-1 in Iran, we found a correlation between CTG expansion and age of onset, temporalis wasting and mental disability. No correlation between CTG expansion and electrodiagnostic and other clinical findings were detected.

  17. Sarcolipin deletion exacerbates soleus muscle atrophy and weakness in phospholamban overexpressing mice

    PubMed Central

    Fajardo, Val A.; Gamu, Daniel; Mitchell, Andrew; Bloemberg, Darin; Bombardier, Eric; Chambers, Paige J.; Bellissimo, Catherine; Quadrilatero, Joe; Tupling, A. Russell

    2017-01-01

    Sarcolipin (SLN) and phospholamban (PLN) are two small proteins that regulate the sarco(endo)plasmic reticulum Ca2+-ATPase pumps. In a recent study, we discovered that Pln overexpression (PlnOE) in slow-twitch type I skeletal muscle fibers drastically impaired SERCA function and caused a centronuclear myopathy-like phenotype, severe muscle atrophy and weakness, and an 8 to 9-fold upregulation of SLN protein in the soleus muscles. Here, we sought to determine the physiological role of SLN upregulation, and based on its role as a SERCA inhibitor, we hypothesized that it would represent a maladaptive response that contributes to the SERCA dysfunction and the overall myopathy observed in the PlnOE mice. To this end, we crossed Sln-null (SlnKO) mice with PlnOE mice to generate a PlnOE/SlnKO mouse colony and assessed SERCA function, CNM pathology, in vitro contractility, muscle mass, calcineurin signaling, daily activity and food intake, and proteolytic enzyme activity. Our results indicate that genetic deletion of Sln did not improve SERCA function nor rescue the CNM phenotype, but did result in exacerbated muscle atrophy and weakness, due to a failure to induce type II fiber compensatory hypertrophy and a reduction in total myofiber count. Mechanistically, our findings suggest that impaired calcineurin activation and resultant decreased expression of stabilin-2, and/or impaired autophagic signaling could be involved. Future studies should examine these possibilities. In conclusion, our study demonstrates the importance of SLN upregulation in combating muscle myopathy in the PlnOE mice, and since SLN is upregulated across several myopathies, our findings may reveal SLN as a novel and universal therapeutic target. PMID:28278204

  18. Compensatory Strategies during Manual Wheelchair Propulsion in Response to Weakness in Individual Muscle Groups: A Simulation Study

    PubMed Central

    Slowik, Jonathan S.; McNitt-Gray, Jill L.; Requejo, Philip S.; Mulroy, Sara J.; Neptune, Richard R.

    2016-01-01

    Background The considerable physical demand placed on the upper extremity during manual wheelchair propulsion is distributed among the individual muscles. The strategy used to distribute the workload is likely influenced by the relative force-generating capacities of individual muscles, and some strategies may be associated with a higher injury risk than others. The objective of this study was to use forward dynamics simulations of manual wheelchair propulsion to identify compensatory strategies that can be used to overcome weakness in individual muscle groups and identify specific strategies that may increase injury risk. Identifying these strategies can provide rationale for the design of targeted rehabilitation programs aimed at preventing the development of pain and injury in manual wheelchair users. Methods Muscle-actuated forward dynamics simulations of manual wheelchair propulsion were analyzed to identify compensatory strategies in response to individual muscle group weakness, using individual muscle mechanical power and stress as measures of upper extremity demand. Findings The simulation analyses found the upper extremity to be robust to weakness in any single muscle group as the remaining groups were able to compensate and restore normal propulsion mechanics. The rotator cuff muscles experienced relatively high muscle stress levels and exhibited compensatory relationships with the deltoid muscles. Interpretation These results underline the importance of strengthening the rotator cuff muscles and supporting muscles whose contributions do not increase the potential for impingement (i.e., the thoracohumeral depressors) and minimize the risk of upper extremity injury in manual wheelchair users. PMID:26945719

  19. Sildenafil reduces respiratory muscle weakness and fibrosis in the mdx mouse model of Duchenne muscular dystrophy.

    PubMed

    Percival, Justin M; Whitehead, Nicholas P; Adams, Marvin E; Adamo, Candace M; Beavo, Joseph A; Froehner, Stanley C

    2012-09-01

    Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy caused by mutations in the dystrophin gene. Loss of dystrophin initiates a progressive decline in skeletal muscle integrity and contractile capacity which weakens respiratory muscles including the diaphragm, culminating in respiratory failure, the leading cause of morbidity and mortality in DMD patients. At present, corticosteroid treatment is the primary pharmacological intervention in DMD, but has limited efficacy and adverse side effects. Thus, there is an urgent need for new safe, cost-effective, and rapidly implementable treatments that slow disease progression. One promising new approach is the amplification of nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signalling pathways with phosphodiesterase 5 (PDE5) inhibitors. PDE5 inhibitors serve to amplify NO signalling that is attenuated in many neuromuscular diseases including DMD. We report here that a 14-week treatment of the mdx mouse model of DMD with the PDE5 inhibitor sildenafil (Viagra(®), Revatio(®)) significantly reduced mdx diaphragm muscle weakness without impacting fatigue resistance. In addition to enhancing respiratory muscle contractility, sildenafil also promoted normal extracellular matrix organization. PDE5 inhibition slowed the establishment of mdx diaphragm fibrosis and reduced matrix metalloproteinase-13 (MMP-13) expression. Sildenafil also normalized the expression of the pro-fibrotic (and pro-inflammatory) cytokine tumour necrosis factor α (TNFα). Sildenafil-treated mdx diaphragms accumulated significantly less Evans Blue tracer dye than untreated controls, which is also indicative of improved diaphragm muscle health. We conclude that sildenafil-mediated PDE5 inhibition significantly reduces diaphragm respiratory muscle dysfunction and pathology in the mdx mouse model of Duchenne muscular dystrophy. This study provides new insights into the therapeutic utility of targeting defects in NO

  20. Does parkinsonian action tremor contribute to muscle weakness in Parkinson's disease?

    PubMed

    Brown, P; Corcos, D M; Rothwell, J C

    1997-03-01

    The aim of this study was to see whether action tremor contributes to the weakness which can be measured in some muscles in patients with Parkinson's disease, by preventing fully fused contraction of motor units. Strength and action tremor were recorded during maximal wrist extension in patients when they were on and off antiparkinsonian medication, and in age- and sex-matched healthy subjects. Peak torque and mean rectified EMG levels were reduced by 25% and 30% (n = 7), respectively, when patients were off medication (compared with when they were on medication). In parkinsonian patients off treatment, action tremor was visible in torque and EMG records, and had a frequency of approximately 10 Hz. The absolute amplitude of this tremor was considerably smaller in patients on medication and in control subjects. In patients, medication reduced action tremor in torque and EMG by 37% and 57%, respectively, so that tremor amplitude approached that in normals. Similar changes were seen when action tremor was expressed as % peak torque of % mean rectified EMG. In parkinsonian patients off medication, a 10-Hz synchronizing influence dominates muscle activity at the wrist. The results is an incompletely fused muscle contraction, which is an important factor contributing to the weakness present in the off-medication state. Antiparkinsonian medication releases motor units from the 10-Hz synchronizing influence, enabling higher discharge rates, fused contraction and improved force generation.

  1. Abductor pollicis longus tendon division with swan neck thumb deformity.

    PubMed

    Zacharia, Balaji; Puthezhath, Kishore

    2012-08-01

    Swan neck thumb deformity can be caused by osteoarthritis, rheumatoid arthritis, systemic lupus erythematosus, tendon transfers and paralytic diseases. Abductor pollicis longus is one of the major stabilizing tendon of the carpometacarpal joint of thumb. To the best of our knowledge, swan neck thumb deformity owing to division of abductor pollicis longus tendon is rare. In this article, we describe a case of isolated division of abductor pollicis longus tendon presenting with swan-neck deformity of thumb and discuss the mechanism, management and outcome. The patient was treated by repair of the divided tendon using palmaris longus tendon graft. At approximately 107 weeks following treatment, the patient was having full range of thumb movement and the deformity completely disappeared. We also describe the unusual mechanism whereby an isolated division of abductor pollicis longus tendon results in swan neck thumb deformity. Level of clinical evidence IV.

  2. Isokinetic muscle testing for weak patients suffering from neuromuscular disorders: a reliability study.

    PubMed

    Tiffreau, Vincent; Ledoux, Isabelle; Eymard, Bruno; Thévenon, André; Hogrel, Jean-Yves

    2007-07-01

    Precise, sensitive muscle strength testing methods are needed to investigate muscle function in patients with neuromuscular disorders (NMD). Here, we describe an isokinetic knee flexor and extensor testing procedure using the Biodex 3's continuous passive motion (CPM) mode. The torque values recorded during passive isokinetic motion were subtracted from the torque values obtained for the same movement with maximal, concentric effort. The aims of the present study were to (i) evaluate the method's reliability in NMD patients presenting mild to severe muscle weakness and (ii) study the relationship between manual muscle testing (MMT) and isokinetic dynamometry. The fifteen participating patients were tested twice; the respective intraclass correlation coefficients (ICCs) for the two sessions ranged from 0.91 to 0.99 for the peak torque, work and power and from 0.50 to 0.90 for the angle at peak torque. The Spearman rho correlation coefficients comparing isokinetic values and MMT values ranged from 0.67 to 0.74 (p<0.01). This reliable, dynamic method appears to be of great value in NMD evaluation when sensitive strength measurement at the knee is required.

  3. Resistance versus endurance training in patients with COPD and peripheral muscle weakness.

    PubMed

    Spruit, M A; Gosselink, R; Troosters, T; De Paepe, K; Decramer, M

    2002-06-01

    The effects of endurance training on exercise capacity and health-related quality of life (HRQL) in chronic obstructive pulmonary disease (COPD) patients have been studied thoroughly, while resistance training has been rarely evaluated. This study investigated the effects of resistance training in comparison with endurance training in patients with moderate to severe COPD and peripheral muscle weakness (isometric knee extension peak torque <75% predicted). Forty-eight patients (age 64+/-8 yrs, forced expiratory volume in one second 38+/-17% pred) were randomly assigned to resistance training (RT, n=24) or endurance training (ET, n=24). The former consisted of dynamic strengthening exercises. The latter consisted of walking, cycling and arm cranking. Respiratory and peripheral muscle force, exercise capacity, and HRQL were re-evaluated in all patients who completed the 12-week rehabilitation (RT n=14, ET n=16). Statistically significant increases in knee extension peak torque (RT 20+/-21%, ET 42+/-21%), maximal knee flexion force (RT 31+/-39%, ET 28+/-37%), elbow flexion force (RT 24+/-19%, ET 33+/-25%), 6-min walking distance (6MWD) (RT 79+/-74 m, ET 95+/-57 m), maximum workload (RT 15+/-16 Watt, ET 14+/-13 Watt) and HRQL (RT 16+/-25 points, ET 16+/-15 points) were observed. No significant differences in changes in HRQL and 6MWD were seen between the two treatments. Resistance training and endurance training have similar effects on peripheral muscle force, exercise capacity and health-related quality of life in chronic obstructive pulmonary disease patients with peripheral muscle weakness.

  4. Age-Related Weakness of Proximal Muscle Studied with Motor Cortical Mapping: A TMS Study

    PubMed Central

    Plow, Ela B.; Varnerin, Nicole; Cunningham, David A.; Janini, Daniel; Bonnett, Corin; Wyant, Alexandria; Hou, Juliet; Siemionow, Vlodek; Wang, Xiao-Feng; Machado, Andre G.; Yue, Guang H.

    2014-01-01

    Aging-related weakness is due in part to degeneration within the central nervous system. However, it is unknown how changes to the representation of corticospinal output in the primary motor cortex (M1) relate to such weakness. Transcranial magnetic stimulation (TMS) is a noninvasive method of cortical stimulation that can map representation of corticospinal output devoted to a muscle. Using TMS, we examined age-related alterations in maps devoted to biceps brachii muscle to determine whether they predicted its age-induced weakness. Forty-seven right-handed subjects participated: 20 young (22.6±0.90 years) and 27 old (74.96±1.35 years). We measured strength as force of elbow flexion and electromyographic activation of biceps brachii during maximum voluntary contraction. Mapping variables included: 1) center of gravity or weighted mean location of corticospinal output, 2) size of map, 3) volume or excitation of corticospinal output, and 4) response density or corticospinal excitation per unit area. Center of gravity was more anterior in old than in young (p<0.001), though there was no significant difference in strength between the age groups. Map size, volume, and response density showed no significant difference between groups. Regardless of age, center of gravity significantly predicted strength (β = −0.34, p = 0.005), while volume adjacent to the core of map predicted voluntary activation of biceps (β = 0.32, p = 0.008). Overall, the anterior shift of the map in older adults may reflect an adaptive change that allowed for the maintenance of strength. Laterally located center of gravity and higher excitation in the region adjacent to the core in weaker individuals could reflect compensatory recruitment of synergistic muscles. Thus, our study substantiates the role of M1 in adapting to aging-related weakness and subtending strength and muscle activation across age groups. Mapping from M1 may offer foundation for an examination of mechanisms

  5. Late-onset cervicoscapular muscle atrophy and weakness after radiotherapy for Hodgkin disease: a case series.

    PubMed

    Furby, A; Béhin, A; Lefaucheur, J-P; Beauvais, K; Marcorelles, P; Mussini, J-M; Bassez, G; Créange, A; Eymard, B; Pénisson-Besnier, I

    2010-01-01

    Patients with cervical or mediastinal Hodgkin disease (HD) classically underwent chemotherapy plus extended-field radiation therapy. We report six patients who gradually developed severe atrophy and weakness of cervical paraspinal and shoulder girdle muscles 5-30 years after mantle irradiation for HD. Although clinical presentation was uniform, including a dropped head syndrome, electrophysiological and pathological findings were rather heterogeneous. Either neurogenic or myogenic processes may be involved and sometimes combined. We discuss the pathophysiological mechanisms underlying these cervicoscapular motor complications of mantle irradiation in HD.

  6. Q-angle in patellofemoral pain: relationship with dynamic knee valgus, hip abductor torque, pain and function☆

    PubMed Central

    Almeida, Gabriel Peixoto Leão; Silva, Ana Paula de Moura Campos Carvalho e; França, Fábio Jorge Renovato; Magalhães, Maurício Oliveira; Burke, Thomaz Nogueira; Marques, Amélia Pasqual

    2016-01-01

    Objective To investigate the relationship between the q-angle and anterior knee pain severity, functional capacity, dynamic knee valgus and hip abductor torque in women with patellofemoral pain syndrome (PFPS). Methods This study included 22 women with PFPS. The q-angle was assessed using goniometry: the participants were positioned in dorsal decubitus with the knee and hip extended, and the hip and foot in neutral rotation. Anterior knee pain severity was assessed using a visual analog scale, and functional capacity was assessed using the anterior knee pain scale. Dynamic valgus was evaluated using the frontal plane projection angle (FPPA) of the knee, which was recorded using a digital camera during step down, and hip abductor peak torque was recorded using a handheld dynamometer. Results The q-angle did not present any significant correlation with severity of knee pain (r = −0.29; p = 0.19), functional capacity (r = −0.08; p = 0.72), FPPA (r = −0.28; p = 0.19) or isometric peak torque of the abductor muscles (r = −0.21; p = 0.35). Conclusion The q-angle did not present any relationship with pain intensity, functional capacity, FPPA, or hip abductor peak torque in the patients with PFPS. PMID:27069887

  7. [A 63-year-old woman with muscle weakness, myotonia, and parkinsonism].

    PubMed

    Okuma, Y; Tanaka, S; Nomura, Y; Mori, H; Yan, H; Shirai, T; Kondo, T; Segawa, M; Mizuno, Y

    1996-03-01

    We report a 63-year-old woman who presented myotonia and parkinsonism. The patient was well until 15 years of the age when she noted that the ring finger of her left hand at times flexed when she did not intend to do so. She noted weakness in her left upper extremity at the age of 40, and difficulty in relaxing her hand grip at 45. She had an onset of tremor in her right foot at age 50, which was followed by difficulty in gait and hand writing. She was admitted to Juntendo University Urayasu Hospital when she was 63-year-old. Her mother, two sisters, and a son were affected with similar muscle weakness and myotonia. Although some of them developed stooped posture in the late stage of the disease, none of them had overt parkinsonism. General physical examination was unremarkable. Neurologic examination revealed an alert and oriented woman with some recent memory loss. She had bilateral ptosis, facial weakness, and a masked face. Myerson's sign was present. Her speech was small and monotonous. The sternocleidomastoid muscles were markedly atrophic and weak. The remaining of the cranial nerves were intact. She walked in small steps with freezing with support. She showed bradykinesia, retropulsion, and resting tremor in her right leg. Slight distal dominant weakness was noted in both upper and lower extremities more on the left. No cerebellar signs were noted. Muscle stretch reflexes were within normal limits in the upper extremities and diminished in the lower limbs. Sensation was intact. Routine laboratory findings were unremarkable. Cranial CT scan and MRI revealed slight cortical atrophy and leukoaraiosis. She responded to levodopa and she became able to walk by herself. She was transferred to another hospital one month after her admission. She had several bouts of airway obstruction with one episode of respiratory arrest. She expired six month after the transfer. The patient was discussed in a neurological CPC, and the chief discussant arrived at the conclusion

  8. First results about recovery of walking function in patients with intensive care unit-acquired muscle weakness from the General Weakness Syndrome Therapy (GymNAST) cohort study

    PubMed Central

    Mehrholz, Jan; Mückel, Simone; Oehmichen, Frank; Pohl, Marcus

    2015-01-01

    Objectives To describe the time course of recovery of walking function and other activities of daily living in patients with intensive care unit (ICU)-acquired muscle weakness. Design This is a cohort study. Participants We included critically ill patients with ICU-acquired muscle weakness. Setting Post-acute ICU and rehabilitation units in Germany. Measures We measured walking function, muscle strength, activities in daily living, motor and cognitive function. Results We recruited 150 patients (30% female) who fulfilled our inclusion and exclusion criteria. The primary outcome recovery of walking function was achieved after a median of 28.5 days (IQR=45) after rehabilitation onset and after a median of 81.5 days (IQR=64) after onset of illness. Our final multivariate model for recovery of walking function included two clinical variables from baseline: the Functional Status Score ICU (adjusted HR=1.07 (95% CI 1.03 to 1.12) and the ability to reach forward in cm (adjusted HR=1.02 (95% CI 1.00 to 1.04). All secondary outcomes but not pain improved significantly in the first 8 weeks after study onset. Conclusions We found good recovery of walking function for most patients and described the recovery of walking function of people with ICU-acquired muscle weakness. Trials registrations number Sächsische Landesärztekammer EK-BR-32/13-1; DRKS00007181, German Register of Clinical Trials. PMID:26700274

  9. Vitamin D Status Is Not Associated with Outcomes of Experimentally-Induced Muscle Weakness and Pain in Young, Healthy Volunteers

    PubMed Central

    Ring, Susan M.; Dannecker, Erin A.; Peterson, Catherine A.

    2010-01-01

    Vitamin D receptors have been identified in skeletal muscle; and symptoms of vitamin D deficiency include muscle weakness and pain. Moreover, increased serum 25-hydroxyvitamin D (25(OH)D) concentrations have been associated with improved muscle function. To further clarify the importance of vitamin D to muscle, we examined the association between vitamin D status and exercise-induced muscle pain and weakness in healthy people. Muscle damage to the elbow flexors was induced with eccentric exercise (EE) in 48 individuals (22.5 ± 3.2 yrs). Muscle pain ratings following unloaded movement and peak isometric force (IF) were collected before EE and for 4 days post-EE. Linear regression was used to determine if serum 25(OH)D was a predictor of any outcome. In males, R2-values from 0.48 to 1.00. R2 for IF ranged from 0 to 0.02 and P-values from 0.48 to 1.00. In females, R2 for pain ratings ranged from 0.01 to 0.11 and P-values from 0.14 to 0.59. R2 for IF ranged from 0 to 0.04 and P-values from 0.41 to 0.90. In conclusion, vitamin D status did not predict muscle pain or strength after EE-induced muscle damage in young healthy men and women. PMID:21209718

  10. [Hashimoto's encephalopathy presenting with vertigo and muscle weakness in a male pediatric patient].

    PubMed

    Ueno, Hiroe; Nishizato, Chizuru; Shimazu, Tomoyuki; Watanabe, Hiziri; Mizukami, Tomoyuki; Kosuge, Hiroshi; Ozasa, Shiro; Nomura, Keiko; Kimura, Shigemi; Takahashi, Yukitoshi

    2016-01-01

    Hashimoto's encephalopathy is an anti-thyroid antibody-positive autoimmune encephalopathy. We herein report the case of a 13-year-old male patient with subacute vertigo, muscle weakness in the extremities and gait disturbance who was diagnosed with Hashimoto's encephalopathy. He showed no severe impairment of consciousness and no seizures, and there were no abnormalities on the brain MRI. However, epileptic spike and wave complexes were observed on an electroencephalogram, and a decline in blood flow was diffusely observed on brain SPECT (single photon emission computed tomography). His thyroid function was normal, but he was positive for anti-thyroid antibodies, such as anti-TPO (thyroid peroxidase) antibodies. He was also positive for serum anti-NAE (NH2-terminal alpha-enolase) antibodies. Systemic corticosteroid therapy and high-dose intravenous immunoglobulin therapy were effective, greatly improving his quality of life.

  11. High-intensity interval training prevents oxidant-mediated diaphragm muscle weakness in hypertensive mice.

    PubMed

    Bowen, T Scott; Eisenkolb, Sophia; Drobner, Juliane; Fischer, Tina; Werner, Sarah; Linke, Axel; Mangner, Norman; Schuler, Gerhard; Adams, Volker

    2017-01-01

    Hypertension is a key risk factor for heart failure, with the latter characterized by diaphragm muscle weakness that is mediated in part by increased oxidative stress. In the present study, we used a deoxycorticosterone acetate (DOCA)-salt mouse model to determine whether hypertension could independently induce diaphragm dysfunction and further investigated the effects of high-intensity interval training (HIIT). Sham-treated (n = 11), DOCA-salt-treated (n = 11), and DOCA-salt+HIIT-treated (n = 15) mice were studied over 4 wk. Diaphragm contractile function, protein expression, enzyme activity, and fiber cross-sectional area and type were subsequently determined. Elevated blood pressure confirmed hypertension in DOCA-salt mice independent of HIIT (P < 0.05). Diaphragm forces were impaired by ∼15-20% in DOCA-salt vs. sham-treated mice (P < 0.05), but this effect was prevented after HIIT. Myosin heavy chain (MyHC) protein expression tended to decrease (∼30%; P = 0.06) in DOCA-salt vs. sham- and DOCA-salt+HIIT mice, whereas oxidative stress increased (P < 0.05). Enzyme activity of NADPH oxidase was higher, but superoxide dismutase was lower, with MyHC oxidation elevated by ∼50%. HIIT further prevented direct oxidant-mediated diaphragm contractile dysfunction (P < 0.05) after a 30 min exposure to H2O-2 (1 mM). Our data suggest that hypertension induces diaphragm contractile dysfunction via an oxidant-mediated mechanism that is prevented by HIIT.-Bowen, T. S., Eisenkolb, S., Drobner, J., Fischer, T., Werner, S., Linke, A., Mangner, N., Schuler, G., Adams, V. High-intensity interval training prevents oxidant-mediated diaphragm muscle weakness in hypertensive mice.

  12. The role of the inspiratory muscle weakness in functional capacity in hemodialysis patients

    PubMed Central

    Gomes, Rosalina Tossige; Neves, Camila Danielle Cunha; de Oliveira, Evandro Silveira; Alves, Frederico Lopes; Rodrigues, Vanessa Gomes Brandão; Maciel, Emílio Henrique Barroso

    2017-01-01

    Introduction Inspiratory muscle function may be affected in patients with End-Stage Renal Disease (ESRD), further worsening the functional loss in these individuals. However, the impact of inspiratory muscle weakness (IMW) on the functional capacity (FC) of hemodialysis patients remains unknown. Thus, the present study aimed to evaluate the impact of IMW on FC in ESRD patients undergoing hemodialysis. Materials and methods ESRD patients on hemodialysis treatment for more than six months were evaluated for inspiratory muscle strength and FC. Inspiratory muscle strength was evaluated based on maximal inspiratory pressure (MIP). IMW was defined as MIP values less than 70% of the predicted value. FC was evaluated using the Incremental Shuttle Walk test (ISWT). Patients whose predicted peak oxygen uptake (VO2peak) over the distance walked during the ISWT was less than 16mL/kg/min were considered to have FC impairment. Associations between variables were assessed by linear and logistic regression, with adjustment for age, sex, body mass index (BMI), presence of diabetes and hemoglobin level. Receiver-operating characteristic (ROC) analysis was used to determine different cutoff values of the MIP for normal inspiratory muscle strength and FC. Results Sixty-five ERSD patients (67.7% male), aged 48.2 (44.5–51.9) years were evaluated. MIP was an independent predictor of the distance walked during the ISWT (R2 = 0.44). IMW was an independent predictor of VO2peak < 16mL/kg/min. (OR = 5.7; p = 0.048) in adjusted logistic regression models. ROC curves showed that the MIP cutoff value of 82cmH2O had a sensitivity of 73.5% and specificity of 93.7% in predicting normal inspiratory strength and a sensitivity and specificity of 76.3% and 70.4%, respectively, in predicting VO2peak ≥ 16mL/kg/min. Conclusions IMW is associated with reduced FC in hemodialysis patients. Evaluation of the MIP may be important to functional monitoring in clinical practice and can help in the

  13. Effect of Gender, Disease Duration and Treatment on Muscle Strength in Myasthenia Gravis

    PubMed Central

    Citirak, Gülsenay; Cejvanovic, Sanja; Andersen, Henning; Vissing, John

    2016-01-01

    Introduction The aim of this observational, cross-sectional study was to quantify the potential presence of muscle weakness among patients with generalized myasthenia gravis (gMG). The influence of gender, treatment intensity and disease duration on muscle strength and disease progression was also assessed. Methods Muscle strength was tested in 8 muscle groups by manual muscle testing and by hand-held dynamometry in 107 patients with gMG and 89 healthy age- and gender-matched controls. Disease duration, severity and treatment history were reviewed and compared with muscle strength. Results Patients had reduced strength in all tested muscle group compared to control subjects (p<0.05). Women with gMG were stronger than men (decrease in strength 22.6% vs. 32.7% in men, P<0.05). Regional differences in muscle weakness were also evident, with proximal muscles being more affected. Interestingly, muscle strength did not correlate with disease duration and treatment intensity. Conclusions The results of this study show that in patients with gMG; 1) there is significant muscle weakness, 2) muscle weakness is more pronounced in men than women, 3) shoulder abductors, hip flexors, and neck muscles are the most affected muscle groups and 4) disease duration or treatment intensity alone are not predictors of loss of muscle strength in gMG. PMID:27741232

  14. Immediate Effect of Grade IV Inferior Hip Joint Mobilization on Hip Abductor Torque: A Pilot Study

    PubMed Central

    Makofsky, Howard; Panicker, Siji; Abbruzzese, Jeanine; Aridas, Cynthia; Camp, Michael; Drakes, Jonelle; Franco, Caroline; Sileo, Ray

    2007-01-01

    Joint mobilization and manipulation stimulate mechanoreceptors, which may influence the joint and surrounding muscles. The purpose of this pilot study was to determine the effect of grade IV inferior hip joint mobilization on hip abductor torque. Thirty healthy subjects were randomly assigned to a control group (grade I inferior hip joint mobilization) or an experimental group (grade IV inferior hip joint mobilization). Subjects performed a pre- and post-intervention test of five isometric repetitions on the Cybex Normö dynamometer; the average torque was determined for both pre- and post-intervention measurements. These data were analyzed using the independent samples t-test with the significance level set at P<0.05. The results showed a statistically significant difference between the two groups for an increase in hip abductor torque in the experimental group (P=0.03). The experimental group demonstrated a 17.35% increase in average torque whereas the control group demonstrated a 3.68% decrease in average torque. These findings are consistent with other studies demonstrating that the use of grade IV non-thrust mobilization improves strength immediately post-intervention in healthy individuals. The results of this pilot study provide physical therapists with further support for the utilization of manual therapy in conjunction with therapeutic exercise to enhance muscle strength. PMID:19066650

  15. Hyperhomocysteinemia associated skeletal muscle weakness involves mitochondrial dysfunction and epigenetic modifications.

    PubMed

    Veeranki, Sudhakar; Winchester, Lee J; Tyagi, Suresh C

    2015-05-01

    HHcy has been implicated in elderly frailty, but the underlying mechanisms are poorly understood. Using C57 and CBS+/- mice and C2C12 cell line, we investigated mechanisms behind HHcy induced skeletal muscle weakness and fatigability. Possible alterations in metabolic capacity (levels of LDH, CS, MM-CK and COX-IV), in structural proteins (levels of dystrophin) and in mitochondrial function (ATP production) were examined. An exercise regimen was employed to reverse HHcy induced changes. CBS+/- mice exhibited more fatigability, and generated less contraction force. No significant changes in muscle morphology were observed. However, there is a corresponding reduction in large muscle fiber number in CBS+/- mice. Excess fatigability was not due to changes in key enzymes involved in metabolism, but was due to reduced ATP levels. A marginal reduction in dystrophin levels along with a decrease in mitochondrial transcription factor A (mtTFA) were observed. There was also an increase in the mir-31, and mir-494 quantities that were implicated in dystrophin and mtTFA regulation respectively. The molecular changes elevated during HHcy, with the exception of dystrophin levels, were reversed after exercise. In addition, the amount of NRF-1, one of the transcriptional regulators of mtTFA, was significantly decreased. Furthermore, there was enhancement in mir-494 levels and a concomitant decline in mtTFA protein quantity in homocysteine treated cells. These changes in C2C12 cells were also accompanied by an increase in DNMT3a and DNMT3b proteins and global DNA methylation levels. Together, these results suggest that HHcy plays a causal role in enhanced fatigability through mitochondrial dysfunction which involves epigenetic changes.

  16. Bowman-Birk inhibitor concentrate prevents atrophy, weakness, and oxidative stress in soleus muscle of hindlimb-unloaded mice.

    PubMed

    Arbogast, Sandrine; Smith, Jacqueline; Matuszczak, Yves; Hardin, Brian J; Moylan, Jennifer S; Smith, Jeffrey D; Ware, Jeffrey; Kennedy, Ann R; Reid, Michael B

    2007-03-01

    Antigravity muscles atrophy and weaken during prolonged mechanical unloading caused by bed rest or spaceflight. Unloading also induces oxidative stress in muscle, a putative cause of weakness. We tested the hypothesis that dietary supplementation with Bowman-Birk inhibitor concentrate (BBIC), a soy protein extract, would oppose these changes. Adult mice were fed a diet supplemented with 1% BBIC during hindlimb unloading for up to 12 days. Soleus muscles of mice fed the BBIC-supplemented diet weighed less, developed less force per cross-sectional area, and developed less total force after unloading than controls. BBIC supplementation was protective, blunting decrements in soleus muscle weight and force. Cytosolic oxidant activity was assessed using 2',7'-dichlorofluorescin diacetate. Oxidant activity increased in unloaded muscle, peaking at 3 days and remaining elevated through 12 days of unloading. Increases in oxidant activity correlated directly with loss of muscle mass and were abolished by BBIC supplementation. In vitro assays established that BBIC directly buffers reactive oxygen species and also inhibits serine protease activity. We conclude that dietary supplementation with BBIC protects skeletal muscle during prolonged unloading, promoting redox homeostasis in muscle fibers and blunting atrophy-induced weakness.

  17. EMG biofeedback of the abductor pollicis brevis in piano performance.

    PubMed

    Montes, R; Bedmar, M; Sol Martin, M

    1993-06-01

    The aim of the present study was to apply EMG biofeedback as an auxiliary to piano teaching techniques. We studied the changes in integrated electromyographic activity, using the abductor pollicis brevis functioning as an agonist during the teaching of identical selective movements of piano playing in two groups, one with EMG biofeedback and the other following traditional method of instruction. The analysis of variance revealed an increase in the peak amplitude and the relaxation rate values for the biofeedback group. These results have implications for the application of piano playing techniques and reveal EMG biofeedback as an aid in the teaching of thumb attack with the abductor pollicis brevis as agonist.

  18. Spasmodic muscle cramps and weakness as presenting symptoms in Wilson disease.

    PubMed

    Rosen, John M; Kuntz, Nancy; Melin-Aldana, Hector; Bass, Lee M

    2013-10-01

    Wilson disease (WD) is an autosomal-recessive disorder of hepatic copper metabolism that has tremendous variability in its presentation. Phenotypic diversity of the disease can lead to delayed diagnosis. We describe a case of WD in a 10-year-old boy presenting with 3 months of increasingly intense, spasmodic lower extremity muscle cramps. Physical examination revealed tenderness on calf palpation and dark flat lesions over his ankles, knees, and elbows. Initial testing revealed creatine kinase of 302 IU/L (normal 24-248 IU/L), hemoglobin of 8.9 g/dL (11.5-15.5 g/dL), aspartate aminotransferase of 114 IU/L (16-52 IU/L), alanine aminotransferase of 54 IU/L (2-30 IU/L), and myoglobinuria. Extensive evaluation of his myopathy, including MRI and muscle biopsy, was negative. Additional laboratory tests revealed a prothrombin time of 21.3 seconds (11.8-15.5 seconds), total bilirubin of 1.4 mg/dL (<1 mg/dL), direct bilirubin of 0.5 mg/dL (<0.3 mg/dL), albumin of 2.1 g/dL (3.1-4.6 g/dL), a reticulocyte percentage of 4.5% (0.5%-2.5%), a negative Coombs direct antibody test, ceruloplasmin of 3 mg/dL (21-51 mg/dL), and 24-h urine copper of 393 μg/24 h (15-60 μg/24 h). Liver biopsy showed patchy advanced fibrosis, mild inflammation, positive staining for copper, and a tissue copper concentration of 768 µg/g (10-35 μg/g). Brain MRI revealed symmetric intrinsic T1 shortening within bilateral basal ganglia. Trientene therapy was initiated for WD. Symptoms and laboratory abnormalities resolved and remain normal at 21 months' follow-up. Musculoskeletal involvement in WD is uncommon and typically defined as bone demineralization, arthropathy, or hypokalemic muscle weakness. In patients with unexplained musculoskeletal symptoms and hepatic abnormalities, a diagnosis of WD should be considered and appropriate evaluation initiated.

  19. Nerve root distribution of deltoid and biceps brachii muscle in cervical spondylotic myelopathy: a potential risk factor for postoperative shoulder muscle weakness after posterior decompression.

    PubMed

    Yonemura, Hiroshi; Kaneko, Kazuo; Taguchi, Toshihiko; Fujimoto, Hideaki; Toyoda, Kouichiro; Kawai, Shinya

    2004-01-01

    To investigate the nerve root distribution of deltoid and biceps brachii muscle, compound muscle action potentials (CMAPs) were recorded intraoperatively following nerve root stimulation in cervical spondylotic myelopathy. A total of 19 upper limbs in 12 patients aged 55-72 years (mean, 65.5 years) with cervical spondylotic myelopathy were examined. CMAPs were recorded from deltoid and biceps brachii muscle following C5 and C6 root stimulation. Although both C5 and C6 roots were innervated for deltoid and biceps brachii muscle in all subjects, the amplitude ratio of CMAPs (C5/C6) differed individually depending on the symptomatic intervertebral levels of the spinal cord. The C5 root predominantly innervated both deltoid and biceps brachii in patients with symptomatic cord lesions at the C4-C5 intervertebral level compared to patients with symptomatic cord lesions at the C5-C6 intervertebral level. Although no patients sustained postoperative radiculopathy in our study, severe weakness and unfavorable recovery are expected when the C5 root in patients with C4-C5 myelopathy is damaged. From the electrophysiological aspect, C4-C5 cord lesions are likely to be a potential risk factor for postoperative shoulder muscle weakness in patients with compressive cervical myelopathy.

  20. High Prevalence of Respiratory Muscle Weakness in Hospitalized Acute Heart Failure Elderly Patients

    PubMed Central

    Verissimo, Pedro; Timenetsky, Karina T.; Casalaspo, Thaisa Juliana André; Gonçalves, Louise Helena Rodrigues; Yang, Angela Shu Yun; Eid, Raquel Caserta

    2015-01-01

    Introduction Respiratory Muscle Weakness (RMW) has been defined when the maximum inspiratory pressure (MIP) is lower than 70% of the predictive value. The prevalence of RMW in chronic heart failure patients is 30 to 50%. So far there are no studies on the prevalence of RMW in acute heart failure (AHF) patients. Objectives Evaluate the prevalence of RMW in patients admitted because of AHF and the condition of respiratory muscle strength on discharge from the hospital. Methods Sixty-three patients had their MIP measured on two occasions: at the beginning of the hospital stay, after they had reached respiratory, hemodynamic and clinical stability and before discharge from the hospital. The apparatus and technique to measure MIP were adapted because of age-related limitations of the patients. Data on cardiac ejection fraction, ECG, brain natriuretic peptide (BNP) levels and on the use of noninvasive ventilation (NIV) were collected. Results The mean age of the 63 patients under study was 75 years. On admission the mean ejection fraction was 33% (95% CI: 31–35) and the BNP hormone median value was 726.5 pg/ml (range: 217 to 2283 pg/ml); 65% of the patients used NIV. The median value of MIP measured after clinical stabilization was -52.7 cmH2O (range: -20 to -120 cmH2O); 76% of the patients had MIP values below 70% of the predictive value. On discharge, after a median hospital stay of 11 days, the median MIP was -53.5 cmH2O (range:-20 to -150 cmH2O); 71% of the patients maintained their MIP values below 70% of the predictive value. The differences found were not statistically significant. Conclusion Elderly patients admitted with AHF may present a high prevalence of RMW on admission; this condition may be maintained at similar levels on discharge in a large percentage of these patients, even after clinical stabilization of the heart condition. PMID:25671566

  1. Lung volume recruitment acutely increases respiratory system compliance in individuals with severe respiratory muscle weakness

    PubMed Central

    Molgat-Seon, Yannick; Hannan, Liam M.; Dominelli, Paolo B.; Peters, Carli M.; Fougere, Renee J.; McKim, Douglas A.; Sheel, A. William

    2017-01-01

    The aim of the present study was to determine whether lung volume recruitment (LVR) acutely increases respiratory system compliance (Crs) in individuals with severe respiratory muscle weakness (RMW). Individuals with RMW resulting from neuromuscular disease or quadriplegia (n=12) and healthy controls (n=12) underwent pulmonary function testing and the measurement of Crs at baseline, immediately after, 1 h after and 2 h after a single standardised session of LVR. The LVR session involved 10 consecutive supramaximal lung inflations with a manual resuscitation bag to the highest tolerable mouth pressure or a maximum of 50 cmH2O. Each LVR inflation was followed by brief breath-hold and a maximal expiration to residual volume. At baseline, individuals with RMW had lower Crs than controls (37±5 cmH2O versus 109±10 mL·cmH2O−1, p<0.001). Immediately after LVR, Crs increased by 39.5±9.8% to 50±7 mL·cmH2O−1 in individuals with RMW (p<0.05), while no significant change occurred in controls (p=0.23). At 1 h and 2 h post-treatment, there were no within-group differences in Crs compared to baseline (all p>0.05). LVR had no significant effect on measures of pulmonary function at any time point in either group (all p>0.05). During inflations, mean arterial pressure decreased significantly relative to baseline by 10.4±2.8 mmHg and 17.3±3.0 mmHg in individuals with RMW and controls, respectively (both p<0.05). LVR acutely increases Crs in individuals with RMW. However, the high airway pressures during inflations cause reductions in mean arterial pressure that should be considered when applying this technique. PMID:28326313

  2. Characteristic MRI Findings of upper Limb Muscle Involvement in Myotonic Dystrophy Type 1.

    PubMed

    Sugie, Kazuma; Sugie, Miho; Taoka, Toshio; Tonomura, Yasuyo; Kumazawa, Aya; Izumi, Tesseki; Kichikawa, Kimihiko; Ueno, Satoshi

    2015-01-01

    The objective of our study was to evaluate the relation between muscle MRI findings and upper limb weakness with grip myotonia in patients with myotonic dystrophy type 1 (DM1). Seventeen patients with DM1 were evaluated by manual muscle strength testing and muscle MRI of the upper limbs. Many DM1 patients presenting with decreased grasping power frequently showed high intensity signals in the flexor digitorum profundus (FDP) muscles on T1-weighted imaging. Patients presenting with upper limb weakness frequently also showed high intensity signals in the flexor pollicis longus, abductor pollicis longus, and extensor pollicis muscles. Disturbances of the distal muscles of the upper limbs were predominant in all DM1 patients. Some DM1 patients with a prolonged disease duration showed involvement of not only distal muscles but also proximal muscles in the upper limbs. Muscle involvement of the upper limbs on MRI strongly correlated positively with the disease duration or the numbers of CTG repeats. To our knowledge, this is the first study to provide a detailed description of the distribution and severity of affected muscles of the upper limbs on MRI in patients with DM1. We conclude that muscle MRI findings are very useful for identifying affected muscles and predicting the risk of muscle weakness in the upper limbs of DM1 patients.

  3. Pharmacological strategies in lung cancer-induced cachexia: effects on muscle proteolysis, autophagy, structure, and weakness.

    PubMed

    Chacon-Cabrera, Alba; Fermoselle, Clara; Urtreger, Alejandro J; Mateu-Jimenez, Mercè; Diament, Miriam J; de Kier Joffé, Elisa D Bal; Sandri, Marco; Barreiro, Esther

    2014-11-01

    Cachexia is a relevant comorbid condition of chronic diseases including cancer. Inflammation, oxidative stress, autophagy, ubiquitin-proteasome system, nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPK) are involved in the pathophysiology of cancer cachexia. Currently available treatment is limited and data demonstrating effectiveness in in vivo models are lacking. Our objectives were to explore in respiratory and limb muscles of lung cancer (LC) cachectic mice whether proteasome, NF-κB, and MAPK inhibitors improve muscle mass and function loss through several molecular mechanisms. Body and muscle weights, limb muscle force, protein degradation and the ubiquitin-proteasome system, signaling pathways, oxidative stress and inflammation, autophagy, contractile and functional proteins, myostatin and myogenin, and muscle structure were evaluated in the diaphragm and gastrocnemius of LC (LP07 adenocarcinoma) bearing cachectic mice (BALB/c), with and without concomitant treatment with NF-κB (sulfasalazine), MAPK (U0126), and proteasome (bortezomib) inhibitors. Compared to control animals, in both respiratory and limb muscles of LC cachectic mice: muscle proteolysis, ubiquitinated proteins, autophagy, myostatin, protein oxidation, FoxO-1, NF-κB and MAPK signaling pathways, and muscle abnormalities were increased, while myosin, creatine kinase, myogenin, and slow- and fast-twitch muscle fiber size were decreased. Pharmacological inhibition of NF-κB and MAPK, but not the proteasome system, induced in cancer cachectic animals, a substantial restoration of muscle mass and force through a decrease in muscle protein oxidation and catabolism, myostatin, and autophagy, together with a greater content of myogenin, and contractile and functional proteins. Attenuation of MAPK and NF-κB signaling pathway effects on muscles is beneficial in cancer-induced cachexia.

  4. The weak link: do muscle properties determine locomotor performance in frogs?

    PubMed Central

    Roberts, Thomas J.; Abbott, Emily M.; Azizi, Emanuel

    2011-01-01

    Muscles power movement, yet the conceptual link between muscle performance and locomotor performance is poorly developed. Frog jumping provides an ideal system to probe the relationship between muscle capacity and locomotor performance, because a jump is a single discrete event and mechanical power output is a critical determinant of jump distance. We tested the hypothesis that interspecific variation in jump performance could be explained by variability in available muscle power. We used force plate ergometry to measure power produced during jumping in Cuban tree frogs (Osteopilus septentrionalis), leopard frogs (Rana pipiens) and cane toads (Bufo marinus). We also measured peak isotonic power output in isolated plantaris muscles for each species. As expected, jump performance varied widely. Osteopilus septentrionalis developed peak power outputs of 1047.0 ± 119.7 W kg−1 hindlimb muscle mass, about five times that of B. marinus (198.5 ± 54.5 W kg−1). Values for R. pipiens were intermediate (543.9 ± 96.2 W kg−1). These differences in jump power were not matched by differences in available muscle power, which were 312.7 ± 28.9, 321.8 ± 48.5 and 262.8 ± 23.2 W kg−1 muscle mass for O. septentrionalis, R. pipiens and B. marinus, respectively. The lack of correlation between available muscle power and jump power suggests that non-muscular mechanisms (e.g. elastic energy storage) can obscure the link between muscle mechanical performance and locomotor performance. PMID:21502120

  5. Intense intermittent exercise provides weak stimulus for vascular endothelial growth factor secretion and capillary growth in skeletal muscle.

    PubMed

    Hoier, B; Passos, M; Bangsbo, J; Hellsten, Y

    2013-02-01

    The effect of acute intense intermittent exercise compared with moderate-intensity exercise on angiogenic factors and the effect of 4 weeks of intense intermittent training on capillary growth were examined in nine healthy young men, preconditioned by moderate-intensity endurance training. The intense training consisted of 24 bouts of 1 min cycling at an initial work rate of 316 ± 19 W (~117% of pretraining maximal oxygen uptake), performed three times per week. Skeletal muscle biopsies and muscle microdialysates were obtained from the vastus lateralis before, during and after acute exercise performed at either moderate or high intensity. Comparison of the response in angiogenic factors to acute moderate- versus high-intensity exercise, performed prior to the intense training intervention, revealed that intense exercise resulted in a markedly lower (~60%; P < 0.05) increase in interstitial vascular endothelial growth factor than did moderate-intensity exercise. Muscle interstitial fluid obtained during moderate-intensity exercise increased endothelial cell proliferation in vitro more than interstitial fluid obtained during intense exercise (sixfold versus 2.5-fold, respectively; P < 0.05). The 4 weeks of high-intensity training did not lead to an increased capillarization in the muscle but abolished the exercise-induced increase in mRNA for several angiogenic factors, increased the protein levels of endothelial nitric oxide synthase, lowered the protein levels of thrombospondin-1 in muscle but increased the interstitial protein levels of thrombospondin-1. We conclude that intense intermittent exercise provides a weak stimulus for vascular endothelial growth factor secretion and endothelial cell proliferation and that intense intermittent training does not induce a sufficient angiogenic stimulus to induce capillary growth in muscle previously conditioned by moderate-intensity exercise.

  6. Misregulated alternative splicing of BIN1 is associated with T tubule alterations and muscle weakness in myotonic dystrophy.

    PubMed

    Fugier, Charlotte; Klein, Arnaud F; Hammer, Caroline; Vassilopoulos, Stéphane; Ivarsson, Ylva; Toussaint, Anne; Tosch, Valérie; Vignaud, Alban; Ferry, Arnaud; Messaddeq, Nadia; Kokunai, Yosuke; Tsuburaya, Rie; de la Grange, Pierre; Dembele, Doulaye; Francois, Virginie; Precigout, Guillaume; Boulade-Ladame, Charlotte; Hummel, Marie-Christine; Lopez de Munain, Adolfo; Sergeant, Nicolas; Laquerrière, Annie; Thibault, Christelle; Deryckere, François; Auboeuf, Didier; Garcia, Luis; Zimmermann, Pascale; Udd, Bjarne; Schoser, Benedikt; Takahashi, Masanori P; Nishino, Ichizo; Bassez, Guillaume; Laporte, Jocelyn; Furling, Denis; Charlet-Berguerand, Nicolas

    2011-06-01

    Myotonic dystrophy is the most common muscular dystrophy in adults and the first recognized example of an RNA-mediated disease. Congenital myotonic dystrophy (CDM1) and myotonic dystrophy of type 1 (DM1) or of type 2 (DM2) are caused by the expression of mutant RNAs containing expanded CUG or CCUG repeats, respectively. These mutant RNAs sequester the splicing regulator Muscleblind-like-1 (MBNL1), resulting in specific misregulation of the alternative splicing of other pre-mRNAs. We found that alternative splicing of the bridging integrator-1 (BIN1) pre-mRNA is altered in skeletal muscle samples of people with CDM1, DM1 and DM2. BIN1 is involved in tubular invaginations of membranes and is required for the biogenesis of muscle T tubules, which are specialized skeletal muscle membrane structures essential for excitation-contraction coupling. Mutations in the BIN1 gene cause centronuclear myopathy, which shares some histopathological features with myotonic dystrophy. We found that MBNL1 binds the BIN1 pre-mRNA and regulates its alternative splicing. BIN1 missplicing results in expression of an inactive form of BIN1 lacking phosphatidylinositol 5-phosphate-binding and membrane-tubulating activities. Consistent with a defect of BIN1, muscle T tubules are altered in people with myotonic dystrophy, and membrane structures are restored upon expression of the normal splicing form of BIN1 in muscle cells of such individuals. Finally, reproducing BIN1 splicing alteration in mice is sufficient to promote T tubule alterations and muscle weakness, a predominant feature of myotonic dystrophy.

  7. Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy.

    PubMed

    Ebert, Scott M; Dyle, Michael C; Bullard, Steven A; Dierdorff, Jason M; Murry, Daryl J; Fox, Daniel K; Bongers, Kale S; Lira, Vitor A; Meyerholz, David K; Talley, John J; Adams, Christopher M

    2015-10-16

    Aging reduces skeletal muscle mass and strength, but the underlying molecular mechanisms remain elusive. Here, we used mouse models to investigate molecular mechanisms of age-related skeletal muscle weakness and atrophy as well as new potential interventions for these conditions. We identified two small molecules that significantly reduce age-related deficits in skeletal muscle strength, quality, and mass: ursolic acid (a pentacyclic triterpenoid found in apples) and tomatidine (a steroidal alkaloid derived from green tomatoes). Because small molecule inhibitors can sometimes provide mechanistic insight into disease processes, we used ursolic acid and tomatidine to investigate the pathogenesis of age-related muscle weakness and atrophy. We found that ursolic acid and tomatidine generate hundreds of small positive and negative changes in mRNA levels in aged skeletal muscle, and the mRNA expression signatures of the two compounds are remarkably similar. Interestingly, a subset of the mRNAs repressed by ursolic acid and tomatidine in aged muscle are positively regulated by activating transcription factor 4 (ATF4). Based on this finding, we investigated ATF4 as a potential mediator of age-related muscle weakness and atrophy. We found that a targeted reduction in skeletal muscle ATF4 expression reduces age-related deficits in skeletal muscle strength, quality, and mass, similar to ursolic acid and tomatidine. These results elucidate ATF4 as a critical mediator of age-related muscle weakness and atrophy. In addition, these results identify ursolic acid and tomatidine as potential agents and/or lead compounds for reducing ATF4 activity, weakness, and atrophy in aged skeletal muscle.

  8. Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy*

    PubMed Central

    Ebert, Scott M.; Dyle, Michael C.; Bullard, Steven A.; Dierdorff, Jason M.; Murry, Daryl J.; Fox, Daniel K.; Bongers, Kale S.; Lira, Vitor A.; Meyerholz, David K.; Talley, John J.; Adams, Christopher M.

    2015-01-01

    Aging reduces skeletal muscle mass and strength, but the underlying molecular mechanisms remain elusive. Here, we used mouse models to investigate molecular mechanisms of age-related skeletal muscle weakness and atrophy as well as new potential interventions for these conditions. We identified two small molecules that significantly reduce age-related deficits in skeletal muscle strength, quality, and mass: ursolic acid (a pentacyclic triterpenoid found in apples) and tomatidine (a steroidal alkaloid derived from green tomatoes). Because small molecule inhibitors can sometimes provide mechanistic insight into disease processes, we used ursolic acid and tomatidine to investigate the pathogenesis of age-related muscle weakness and atrophy. We found that ursolic acid and tomatidine generate hundreds of small positive and negative changes in mRNA levels in aged skeletal muscle, and the mRNA expression signatures of the two compounds are remarkably similar. Interestingly, a subset of the mRNAs repressed by ursolic acid and tomatidine in aged muscle are positively regulated by activating transcription factor 4 (ATF4). Based on this finding, we investigated ATF4 as a potential mediator of age-related muscle weakness and atrophy. We found that a targeted reduction in skeletal muscle ATF4 expression reduces age-related deficits in skeletal muscle strength, quality, and mass, similar to ursolic acid and tomatidine. These results elucidate ATF4 as a critical mediator of age-related muscle weakness and atrophy. In addition, these results identify ursolic acid and tomatidine as potential agents and/or lead compounds for reducing ATF4 activity, weakness, and atrophy in aged skeletal muscle. PMID:26338703

  9. Acute iliopsoas and adductor brevis abscesses presenting with proximal leg muscle weakness.

    PubMed

    Devetag Chalaupka, F

    2006-06-01

    Pyomyositis is a bacterial infection of skeletal muscle. We describe the clinical case of a 77-year-old woman affected by gait disturbance, repetitive falls, low back pain and left thigh and groin pain, but without symptoms of systemic infection. Computed tomography and magnetic resonance imaging of the abdomen and pelvis showed abscesses in the left psoas and adductor brevis muscles. Investigations of urogenital tract and gastrointestinal system were normal. Systemic antibiotic treatment alone was not efficient, while surgical drainage improved the clinical picture. The aetiological organism, isolated from the abscess, was Staphylococcus aureus. We suggest that this patient had a primary pyomyositis rather than a secondary form. This is the first report of concomitant abscesses of psoas and adductor brevis muscles with early neurological involvement.

  10. Molecular mechanisms underlying skeletal muscle weakness in human cancer: reduced myosin-actin cross-bridge formation and kinetics.

    PubMed

    Toth, Michael J; Miller, Mark S; Callahan, Damien M; Sweeny, Andrew P; Nunez, Ivette; Grunberg, Steven M; Der-Torossian, Hirak; Couch, Marion E; Dittus, Kim

    2013-04-01

    Many patients with cancer experience physical disability following diagnosis, although little is known about the mechanisms underlying these functional deficits. To characterize skeletal muscle adaptations to cancer in humans, we evaluated skeletal muscle structure and contractile function at the molecular, cellular, whole-muscle, and whole-body level in 11 patients with cancer (5 cachectic, 6 noncachectic) and 6 controls without disease. Patients with cancer showed a 25% reduction in knee extensor isometric torque after adjustment for muscle mass (P < 0.05), which was strongly related to diminished power output during a walking endurance test (r = 0.889; P < 0.01). At the cellular level, single fiber isometric tension was reduced in myosin heavy chain (MHC) IIA fibers (P = 0.05) in patients with cancer, which was explained by a reduction (P < 0.05) in the number of strongly bound cross-bridges. In MHC I fibers, myosin-actin cross-bridge kinetics were reduced in patients, as evidenced by an increase in myosin attachment time (P < 0.01); and reductions in another kinetic parameter, myosin rate of force production, predicted reduced knee extensor isometric torque (r = 0.689; P < 0.05). Patients with cancer also exhibited reduced mitochondrial density (-50%; P < 0.001), which was related to increased myosin attachment time in MHC I fibers (r = -0.754; P < 0.01). Finally, no group differences in myofilament protein content or ultrastructure were noted that explained the observed functional alterations. Collectively, our results suggest reductions in myofilament protein function as a potential molecular mechanism contributing to muscle weakness and physical disability in human cancer.

  11. The effects of chest expansion resistance exercise on chest expansion and maximal respiratory pressure in elderly with inspiratory muscle weakness

    PubMed Central

    Kim, Chang-Beom; Yang, Jin-Mo; Choi, Jong-Duk

    2015-01-01

    [Purpose] The aim of this study was to examine the effect of chest expansion resistance exercises (CERE) on chest expansion, maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) in elderly people with inspiratory muscle weakness. [Subjects] Thirty elderly people with inspiratory muscle weakness (MIP < 80% of the predicted value) were randomly and equally assigned to a chest expansion resistance exercise (CERE) group, core conditioning exercise (CCE) group, and control group. [Methods] The intervention was applied to the CERE group and CCE group five times per week, 30 minutes each time, for six weeks. A tapeline was used to measure upper and lower chest expansion. MIP and MEP before and after the intervention were measured and compared. [Results] There was significant improvement in upper and lower chest expansion and MIP after the intervention in both the CERE group and the CCE group, whereas the control group did not show any significant difference. MEP did not significantly change in any of the three groups after the intervention. [Conclusion] The CERE group underwent greater changes than the CCE group, which proves that the CERE is more effective for improving elderly people’s chest expansion capacity and MIP in elderly people. Therefore, application of the CERE by therapists is recommended if the environment and conditions are appropriate for enhancement of chest expansion capacity and MIP in elderly people. PMID:25995570

  12. Superoxide dismutase/catalase mimetic EUK-134 prevents diaphragm muscle weakness in monocrotalin-induced pulmonary hypertension

    PubMed Central

    Tatebayashi, Daisuke; Lee, Jaesik; Westerblad, Håkan; Lanner, Johanna T.

    2017-01-01

    Patients with pulmonary hypertension (PH) suffer from inspiratory insufficiency, which has been associated with intrinsic contractile dysfunction in diaphragm muscle. Here, we examined the role of redox stress in PH-induced diaphragm weakness by using the novel antioxidant, EUK-134. Male Wistar rats were randomly divided into control (CNT), CNT + EUK-134 (CNT + EUK), monocrotaline-induced PH (PH), and PH + EUK groups. PH was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg body weight). EUK-134 (3 mg/kg body weight/day), a cell permeable mimetic of superoxide dismutase (SOD) and catalase, was daily intraperitoneally administered starting one day after induction of PH. After four weeks, diaphragm muscles were excised for mechanical and biochemical analyses. There was a decrease in specific tetanic force in diaphragm bundles from the PH group, which was accompanied by increases in: protein expression of NADPH oxidase 2/gp91phox, SOD2, and catalase; 3-nitrotyrosine content and aggregation of actin; glutathione oxidation. Treatment with EUK-134 prevented the force decrease and the actin modifications in PH diaphragm bundles. These data show that redox stress plays a pivotal role in PH-induced diaphragm weakness. Thus, antioxidant treatment can be a promising strategy for PH patients with inspiratory failure. PMID:28152009

  13. A case of diabetic amyotrophy with severe atrophy and weakness of shoulder girdle muscles showing good response to intravenous immune globulin.

    PubMed

    Wada, Yuko; Yanagihara, Chie; Nishimura, Yo; Oka, Nobuyuki

    2007-01-01

    A 45-year-old man with insulin-dependent diabetic mellitus developed progressive asymmetrical weakness and atrophy of both shoulder girdle muscles within 1 year. In the last month, he also developed slight weakness of both thighs. Neuropathology of the sural nerve showed an axonal degeneration and perivascular inflammation and electromyography revealed neurogenic changes. Because of a diagnosis of suspected diabetic amyotrophy, intravenous immunoglobulin was administered. This treatment produced marked improvement. Physicians should take into account the possibility of diabetic amyotrophy in patients with diabetic mellitus showing primary involvement of shoulder girdle muscles marked by weakness and atrophy.

  14. Can ankle imbalance be a risk factor for tensor fascia lata muscle weakness?

    PubMed

    Zampagni, Maria L; Corazza, I; Molgora, A Paladini; Marcacci, M

    2009-08-01

    Risk factors that can determine knee and ankle injuries have been investigated and causes are probably multifactorial. A possible explanation could be related by the temporary inhibition of muscular control following an alteration of proprioceptive regulation due to the ankle imbalance pathology. The purpose of our study was to validate a new experimental set up to quantify two kinesiologic procedures (Shock Absorber Test (SAT) and Kendall and Kendall's Procedure (KKP)) to verify if a subtalus stimulus in an ankle with imbalance can induce a non-appropriate response of controlateral tensor fascia lata muscle (TFL). Fifteen male soccer players with ankle imbalance (AIG) and 14 healthy (CG) were tested after (TEST) before (NO-TEST) a manual percussion in subtalus joint (SAT). A new tailor-made device equipped with a load cell was used to quantify TFL's strength activation in standardized positions. Two trials for each subject were performed, separated by at least one 4-min resting interval. In NO-TEST conditions both AIG and CG showed a progressive adaptation of the subject to the force imposed by operator. No reduction in mean force, mean peak force, and muscle force duration (p>0.5). AIG presented significant differences (mean difference 0.92+/-0.46 s; p=0.000) in muscle force duration in TEST conditions. Our results indicated that "wrong" proprioceptive stimuli coming from the subtalus joint in AIG might induce inhibition in terms of duration of TFL muscle altering the knee stability. This kinesiological evaluation might be useful to prevent ankle and knee injuries.

  15. Respiratory muscle weakness in uremic patients under continuous ambulatory peritoneal dialysis.

    PubMed

    Gómez-Fernández, P; Sánchez Agudo, L; Calatrava, J M; Escuin, F; Selgas, R; Martínez, M E; Montero, A; Sánchez-Sicilia, L

    1984-01-01

    The increasingly frequent use of continuous ambulatory peritoneal dialysis (CAPD) as substitutive therapy in terminal renal failure has induced the investigation of the advantages and disadvantages of this therapeutic modality. The effects of CAPD on pulmonary function are one of the aspects currently under study. Based on previous data suggesting the existence of extrapulmonary ventilatory restriction in uremic patients under CAPD, we have studied in these patients the respiratory muscle function as expressed in the maximal inspiratory pressure (MIP) and assessed the impact of the infusion of 2 liters of dialysis fluid into the peritoneal cavity on both MIP and the pulmonary volumes. Uremic patients evidenced significantly lower MIP values as compared with healthy controls. The filling of the peritoneal cavity induced, both in the supine and in the sitting position, a restrictive effect and an increase in the inspiratory capacity. We conclude that uremic patients under CAPD evidence a respiratory muscle dysfunction of as yet unclear cause. Our findings further suggest that the infusion of 2 liters of dialysis fluid into the peritoneal cavity induces not only a restrictive effect, but also an increase in the strength of the respiratory muscles, the latter effect being probably due to increased diaphragmatic contractility.

  16. Muscle weakness, spasticity and disuse contribute to demineralization and geometric changes in the radius following chronic stroke

    PubMed Central

    Pang, Marco Y.C.; Ashe, Maureen C.; Eng, Janice J.

    2011-01-01

    Following a stroke, demineralization and geometric changes occur in bone as a result of disuse and residual impairments and these can contribute to an increased risk of fragility fractures. This study used peripheral quantitative computed tomography (pQCT) to evaluate volumetric bone mineral density and geometry at the midshaft radius in people living with chronic stroke. Older individuals with chronic stroke were recruited. Each subject underwent a pQCT scan of the midshaft radius at the 30% site on both upper limbs. Muscle strength, motor function, spasticity, and chronic disuse were also evaluated. Data from 47 subjects (19 women) were assessed. A significant difference was found between the two limbs for cortical bone mineral content, cortical bone mineral density, cortical thickness, and polar stress-strain index. There was no significant side-to-side difference in total bone area. Percent side-to-side difference in muscle strength, spasticity, and chronic disuse were significant determinants of percent side-to-side difference in cortical bone mineral content and cortical thickness. The findings suggest that following chronic stroke, endosteal resorption of the midshaft radius occurred with a preservation of total bone area. Muscle weakness, spasticity, chronic disuse significantly contributed to demineralization and geometric changes in the radius following chronic stroke. PMID:17401512

  17. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    PubMed Central

    Meskers, Carel GM; Schouten, Alfred C; de Groot, Jurriaan H; de Vlugt, Erwin; van Hilten, Bob JJ; van der Helm, Frans CT; Arendzen, Hans JH

    2009-01-01

    Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Conclusion Post stroke, we found active posture tasking to be dominated by: 1) muscle weakness and 2) lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders. PMID:19627607

  18. Progressive muscle weakness after high-dose steroids in two children with CIDP.

    PubMed

    Rostasy, Kevin M; Diepold, Katharina; Buckard, Johannes; Brockmann, Knut; Wilken, Bernd; Hanefeld, Folker

    2003-09-01

    Corticosteroids and intravenous immunoglobulins belong to the first line of treatment in chronic inflammatory demyelinating polyneuropathy. In patients with a progressive course, plasma exchange and immunomodulatory drugs are added to the regimen. To reduce the side effects of long-term oral prednisolone, high-dose pulsatile intravenous methylprednisolone treatment has been advocated. We report two children with chronic inflammatory demyelinating polyneuropathy who, after high-dose intravenous pulsatile methylprednisolone, experienced a significant clinical deterioration with profound loss of muscle strength. Both patients improved after changing treatment to immunoglobulins in one and cyclosporine combined with immunoglobulins and oral prednisolone in the other.

  19. Increased CaVbeta1A expression with aging contributes to skeletal muscle weakness.

    PubMed

    Taylor, Jackson R; Zheng, Zhenlin; Wang, Zhong-Min; Payne, Anthony M; Messi, María L; Delbono, Osvaldo

    2009-09-01

    Ca2+ release from the sarcoplasmic reticulum (SR) into the cytosol is a crucial part of excitation-contraction (E-C) coupling. Excitation-contraction uncoupling, a deficit in Ca2+ release from the SR, is thought to be responsible for at least some of the loss in specific force observed in aging skeletal muscle. Excitation-contraction uncoupling may be caused by alterations in expression of the voltage-dependent calcium channel alpha1s (CaV1.1) and beta1a (CaVbeta1a) subunits, both of which are necessary for E-C coupling to occur. While previous studies have found CaV1.1 expression declines in old rodents, CaVbeta1a expression has not been previously examined in aging models. Western blot analysis shows a substantial increase of CaVbeta1a expression over the full lifespan of Friend Virus B (FVB) mice. To examine the specific effects of CaVbeta1a overexpression, a CaVbeta1a-YFP plasmid was electroporated in vivo into young animals. The resulting increase in expression of CaVbeta1a corresponded to decline of CaV1.1 over the same time period. YFP fluorescence, used as a measure of CaVbeta1a-YFP expression in individual fibers, also showed an inverse relationship with charge movement, measured using the whole-cell patch-clamp technique. Specific force was significantly reduced in young CaVbeta1a-YFP electroporated muscle fibers compared with sham-electroporated, age-matched controls. siRNA interference of CaVbeta1a in young muscles reduced charge movement, while charge movement in old was restored to young control levels. These studies imply CaVbeta1a serves as both a positive and negative regulator CaV1.1 expression, and that endogenous overexpression of CaVbeta1a during old age may play a role in the loss of specific force.

  20. Progressive skeletal muscle weakness in transgenic mice expressing CTG expansions is associated with the activation of the ubiquitin-proteasome pathway.

    PubMed

    Vignaud, Alban; Ferry, Arnaud; Huguet, Aline; Baraibar, Martin; Trollet, Capucine; Hyzewicz, Janek; Butler-Browne, Gillian; Puymirat, Jack; Gourdon, Genevieve; Furling, Denis

    2010-05-01

    Myotonic dystrophy type 1 (DM1) is a neuromuscular disease caused by the expansion of a CTG repeat in the DMPK gene and characterised by progressive skeletal muscle weakness and wasting. To investigate the effects of the CTG expansion on the physiological function of the skeletal muscles, we have used a transgenic mouse model carrying the human DM1 region with 550 expanded CTG repeats. Maximal force is reduced in the skeletal muscles of 10-month-old but not in 3-month-old DM1 mice when compared to age-matched non-transgenic littermates. The progressive weakness observed in the DM1 mice is directly related to the reduced muscle mass and muscle fibre size. A significant increase in trypsin-like proteasome activity and Fbxo32 expression is also measured in the DM1 muscles indicating that an atrophic process mediated by the ubiquitin-proteasome pathway may contribute to the progressive muscle wasting and weakness in the DM1 mice.

  1. A Comparison of Cough Assistance Techniques in Patients with Respiratory Muscle Weakness

    PubMed Central

    Kim, Sun Mi; Choi, Won Ah; Won, Yu Hui

    2016-01-01

    Purpose To assess the ability of a mechanical in-exsufflator (MI-E), either alone or in combination with manual thrust, to augment cough in patients with neuromuscular disease (NMD) and respiratory muscle dysfunction. Materials and Methods For this randomized crossover single-center controlled trial, patients with noninvasive ventilator-dependent NMD were recruited. The primary outcome was peak cough flow (PCF), which was measured in each patient after a cough that was unassisted, manually assisted following a maximum insufflation capacity (MIC) maneuver, assisted by MI-E, or assisted by manual thrust plus MI-E. The cough augmentation techniques were provided in random order. PCF was measured using a new device, the Cough Aid. Results All 40 enrolled participants (37 males, three females; average age, 20.9±7.2 years) completed the study. The mean (standard deviation) PCFs in the unassisted, manually assisted following an MIC maneuver, MI-E-assisted, and manual thrust plus MI-E-assisted conditions were 95.7 (40.5), 155.9 (53.1), 177.2 (33.9), and 202.4 (46.6) L/min, respectively. All three interventions significantly improved PCF. However, manual assistance following an MIC maneuver was significantly less effective than MI-E alone. Manual thrust plus MI-E was significantly more effective than both of these interventions. Conclusion In patients with NMD and respiratory muscle dysfunction, MI-E alone was more effective than manual assistance following an MIC maneuver. However, MI-E used in conjunction with manual thrust improved PCF even further. PMID:27593879

  2. Knee Joint Contact Mechanics during Downhill Gait and its Relationship with Varus/Valgus Motion and Muscle Strength in Patients with Knee Osteoarthritis

    PubMed Central

    Farrokhi, Shawn; Voycheck, Carrie A.; Gustafson, Jonathan A.; Fitzgerald, G. Kelley; Tashman, Scott

    2015-01-01

    Objective The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA). Methods Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed. Group differences in contact mechanics and frontal-plane motion excursions were compared using analysis of covariance with adjustments for body mass index. Differences in strength were compared using independent sample t-tests. Additionally, linear associations between contact mechanics with frontal-plane knee motion and muscle strength were evaluated using Pearson's correlation coefficients. Results Patients with knee OA demonstrated larger medial/lateral joint contact point excursions (p<0.02) and greater heel-strike joint contact point velocities (p<0.05) for the medial and lateral compartments compared to the control group. The peak medial/lateral joint contact point velocity of the medial compartment was also greater for patients with knee OA compared to their control counterparts (p=0.02). Additionally, patients with knee OA demonstrated significantly increased frontal-plane varus motion excursions (p<0.01) and greater quadriceps and hip abductor muscle weakness (p=0.03). In general, increased joint contact point excursions and velocities in patients with knee OA were linearly associated with greater frontal-plane varus motion excursions (p<0.04) but not with quadriceps or hip abductor strength. Conclusion Altered contact mechanics in patients with knee OA may be related to compromised frontal-plane joint stability but not with

  3. Aromatase inhibitor-induced bone loss increases the progression of estrogen receptor-negative breast cancer in bone and exacerbates muscle weakness in vivo.

    PubMed

    Wright, Laura E; Harhash, Ahmed A; Kozlow, Wende M; Waning, David L; Regan, Jenna N; She, Yun; John, Sutha K; Murthy, Sreemala; Niewolna, Maryla; Marks, Andrew R; Mohammad, Khalid S; Guise, Theresa A

    2017-01-31

    Aromatase inhibitors (AIs) cause muscle weakness, bone loss, and joint pain in up to half of cancer patients. Preclinical studies have demonstrated that increased osteoclastic bone resorption can impair muscle contractility and prime the bone microenvironment to accelerate metastatic growth. We hypothesized that AI-induced bone loss could increase breast cancer progression in bone and exacerbate muscle weakness associated with bone metastases. Female athymic nude mice underwent ovariectomy (OVX) or sham surgery and were treated with vehicle or AI (letrozole; Let). An OVX-Let group was then further treated with bisphosphonate (zoledronic acid; Zol). At week three, trabecular bone volume was measured and mice were inoculated with MDA-MB-231 cells into the cardiac ventricle and followed for progression of bone metastases. Five weeks after tumor cell inoculation, tumor-induced osteolytic lesion area was increased in OVX-Let mice and reduced in OVX-Let-Zol mice compared to sham-vehicle. Tumor burden in bone was increased in OVX-Let mice relative to sham-vehicle and OVX-Let-Zol mice. At the termination of the study, muscle-specific force of the extensor digitorum longus muscle was reduced in OVX-Let mice compared to sham-vehicle mice, however, the addition of Zol improved muscle function. In summary, AI treatment induced bone loss and skeletal muscle weakness, recapitulating effects observed in cancer patients. Prevention of AI-induced osteoclastic bone resorption using a bisphosphonate attenuated the development of breast cancer bone metastases and improved muscle function in mice. These findings highlight the bone microenvironment as a modulator of tumor growth locally and muscle function systemically.

  4. Abductor Hallucis: Anatomical Variation and Its Clinical Implications in the Reconstruction of Chronic Nonhealing Ulcers and Defects of Foot

    PubMed Central

    Chittoria, Ravi Kumar; Pratap, Harsha; Yekappa, Suma Hottigoudar

    2015-01-01

    Abductor hallucis (AH) is an intrinsic muscle of sole of the foot. It is commonly used in the coverage of ankle and heel defects and chronic nonhealing ulcers of the foot; its use is reported to have a favorable long-term outcome. The muscle's apt bulk and size, its simple surgical isolation, absence of donor-site defect, unvaried anatomy, and long neurovascular pedicle are some of the advantages that make it a promising muscle flap. During routine cadaver dissection in the Department of Anatomy of Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India, we identified an anatomical variation in AH in both feet of a 45-year-old embalmed male Indian cadaver. The variant muscle had innumerable proximal attachments, a majority of them arising atypically in the form of tough tendinous slips from the medial intermuscular septum at the junction of central and tibial components of plantar aponeurosis, the medial surface of first metatarsal and the intermuscular septum separating AH from the flexor hallucis brevis. The tendon: muscle ratio was 1.76, higher than the normal reported ratio of 0.56±0.07. This article highlights the variation noted and its implication for clinicians. On Internet search, we did not come across the variations described in our article. Findings of the anatomical variation reported in this article could benefit surgeons who decide to use AH flaps in the future. PMID:26634184

  5. Expression of the inclusion body myopathy 3 mutation in Drosophila depresses myosin function and stability and recapitulates muscle inclusions and weakness

    PubMed Central

    Wang, Yang; Melkani, Girish C.; Suggs, Jennifer A.; Melkani, Anju; Kronert, William A.; Cammarato, Anthony; Bernstein, Sanford I.

    2012-01-01

    Hereditary myosin myopathies are characterized by variable clinical features. Inclusion body myopathy 3 (IBM-3) is an autosomal dominant disease associated with a missense mutation (E706K) in the myosin heavy chain IIa gene. Adult patients experience progressive muscle weakness. Biopsies reveal dystrophic changes, rimmed vacuoles with cytoplasmic inclusions, and focal disorganization of myofilaments. We constructed a transgene encoding E706K myosin and expressed it in Drosophila (E701K) indirect flight and jump muscles to establish a novel homozygous organism with homogeneous populations of fast IBM-3 myosin and muscle fibers. Flight and jump abilities were severely reduced in homozygotes. ATPase and actin sliding velocity of the mutant myosin were depressed >80% compared with wild-type myosin. Light scattering experiments and electron microscopy revealed that mutant myosin heads bear a dramatic propensity to collapse and aggregate. Thus E706K (E701K) myosin appears far more labile than wild-type myosin. Furthermore, mutant fly fibers exhibit ultrastructural hallmarks seen in patients, including cytoplasmic inclusions containing aberrant proteinaceous structures and disorganized muscle filaments. Our Drosophila model reveals the unambiguous consequences of the IBM-3 lesion on fast muscle myosin and fibers. The abnormalities observed in myosin function and muscle ultrastructure likely contribute to muscle weakness observed in our flies and patients. PMID:22496423

  6. Muscle Weakness and Fibrosis Due to Cell Autonomous and Non-cell Autonomous Events in Collagen VI Deficient Congenital Muscular Dystrophy.

    PubMed

    Noguchi, Satoru; Ogawa, Megumu; Malicdan, May Christine; Nonaka, Ikuya; Nishino, Ichizo

    2017-02-01

    Congenital muscular dystrophies with collagen VI deficiency are inherited muscle disorders with a broad spectrum of clinical presentation and are caused by mutations in one of COL6A1-3 genes. Muscle pathology is characterized by fiber size variation and increased interstitial fibrosis and adipogenesis. In this study, we define critical events that contribute to muscle weakness and fibrosis in a mouse model with collagen VI deficiency. The Col6a1(GT/GT) mice develop non-progressive weakness from younger age, accompanied by stunted muscle growth due to reduced IGF-1 signaling activity. In addition, the Col6a1(GT/GT) mice have high numbers of interstitial skeletal muscle mesenchymal progenitor cells, which dramatically increase with repeated myofiber necrosis/regeneration. Our results suggest that impaired neonatal muscle growth and the activation of the mesenchymal cells in skeletal muscles contribute to the pathology of collagen VI deficient muscular dystrophy, and more importantly, provide the insights on the therapeutic strategies for collagen VI deficiency.

  7. Muscle Disorders

    MedlinePlus

    Your muscles help you move and help your body work. Different types of muscles have different jobs. There are many problems that can affect muscles. Muscle disorders can cause weakness, pain or even ...

  8. Passive tension and stiffness of vertebrate skeletal and insect flight muscles: the contribution of weak cross-bridges and elastic filaments.

    PubMed Central

    Granzier, H L; Wang, K

    1993-01-01

    Tension and dynamic stiffness of passive rabbit psoas, rabbit semitendinosus, and waterbug indirect flight muscles were investigated to study the contribution of weak-binding cross-bridges and elastic filaments (titin and minititin) to the passive mechanical behavior of these muscles. Experimentally, a functional dissection of the relative contribution of actomyosin cross-bridges and titin and minititin was achieved by 1) comparing mechanically skinned muscle fibers before and after selective removal of actin filaments with a noncalcium-requiring gelsolin fragment (FX-45), and 2) studying passive tension and stiffness as a function of sarcomere length, ionic strength, temperature, and the inhibitory effect of a carboxyl-terminal fragment of smooth muscle caldesmon. Our data show that weak bridges exist in both rabbit skeletal muscle and insect flight muscle at physiological ionic strength and room temperature. In rabbit psoas fibers, weak bridge stiffness appears to vary with both thin-thick filament overlap and with the magnitude of passive tension. Plots of passive tension versus passive stiffness are multiphasic and strikingly similar for these three muscles of distinct sarcomere proportions and elastic proteins. The tension-stiffness plot appears to be a powerful tool in discerning changes in the mechanical behavior of the elastic filaments. The stress-strain and stiffness-strain curves of all three muscles can be merged into one, by normalizing strain rate and strain amplitude of the extensible segment of titin and minititin, further supporting the segmental extension model of resting tension development. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 PMID:8298040

  9. Recurrent Muscle Weakness with Rhabdomyolysis, Metabolic Crises, and Cardiac Arrhythmia Due to Bi-allelic TANGO2 Mutations

    PubMed Central

    Lalani, Seema R.; Liu, Pengfei; Rosenfeld, Jill A.; Watkin, Levi B.; Chiang, Theodore; Leduc, Magalie S.; Zhu, Wenmiao; Ding, Yan; Pan, Shujuan; Vetrini, Francesco; Miyake, Christina Y.; Shinawi, Marwan; Gambin, Tomasz; Eldomery, Mohammad K.; Akdemir, Zeynep Hande Coban; Emrick, Lisa; Wilnai, Yael; Schelley, Susan; Koenig, Mary Kay; Memon, Nada; Farach, Laura S.; Coe, Bradley P.; Azamian, Mahshid; Hernandez, Patricia; Zapata, Gladys; Jhangiani, Shalini N.; Muzny, Donna M.; Lotze, Timothy; Clark, Gary; Wilfong, Angus; Northrup, Hope; Adesina, Adekunle; Bacino, Carlos A.; Scaglia, Fernando; Bonnen, Penelope E.; Crosson, Jane; Duis, Jessica; Maegawa, Gustavo H.B.; Coman, David; Inwood, Anita; McGill, Jim; Boerwinkle, Eric; Graham, Brett; Beaudet, Art; Eng, Christine M.; Hanchard, Neil A.; Xia, Fan; Orange, Jordan S.; Gibbs, Richard A.; Lupski, James R.; Yang, Yaping

    2016-01-01

    The underlying genetic etiology of rhabdomyolysis remains elusive in a significant fraction of individuals presenting with recurrent metabolic crises and muscle weakness. Using exome sequencing, we identified bi-allelic mutations in TANGO2 encoding transport and Golgi organization 2 homolog (Drosophila) in 12 subjects with episodic rhabdomyolysis, hypoglycemia, hyperammonemia, and susceptibility to life-threatening cardiac tachyarrhythmias. A recurrent homozygous c.460G>A (p.Gly154Arg) mutation was found in four unrelated individuals of Hispanic/Latino origin, and a homozygous ∼34 kb deletion affecting exons 3–9 was observed in two families of European ancestry. One individual of mixed Hispanic/European descent was found to be compound heterozygous for c.460G>A (p.Gly154Arg) and the deletion of exons 3–9. Additionally, a homozygous exons 4–6 deletion was identified in a consanguineous Middle Eastern Arab family. No homozygotes have been reported for these changes in control databases. Fibroblasts derived from a subject with the recurrent c.460G>A (p.Gly154Arg) mutation showed evidence of increased endoplasmic reticulum stress and a reduction in Golgi volume density in comparison to control. Our results show that the c.460G>A (p.Gly154Arg) mutation and the exons 3–9 heterozygous deletion in TANGO2 are recurrent pathogenic alleles present in the Latino/Hispanic and European populations, respectively, causing considerable morbidity in the homozygotes in these populations. PMID:26805781

  10. Recovery from muscle weakness by exercise and FES: lessons from Masters, active or sedentary seniors and SCI patients.

    PubMed

    Carraro, Ugo; Kern, Helmut; Gava, Paolo; Hofer, Christian; Loefler, Stefan; Gargiulo, Paolo; Edmunds, Kyle; Árnadóttir, Íris Dröfn; Zampieri, Sandra; Ravara, Barbara; Gava, Francesco; Nori, Alessandra; Gobbo, Valerio; Masiero, Stefano; Marcante, Andrea; Baba, Alfonc; Piccione, Francesco; Schils, Sheila; Pond, Amber; Mosole, Simone

    2016-09-03

    Many factors contribute to the decline of skeletal muscle that occurs as we age. This is a reality that we may combat, but not prevent because it is written into our genome. The series of records from World Master Athletes reveals that skeletal muscle power begins to decline at the age of 30 years and continues, almost linearly, to zero at the age of 110 years. Here we discuss evidence that denervation contributes to the atrophy and slowness of aged muscle. We compared muscle from lifelong active seniors to that of sedentary elderly people and found that the sportsmen have more muscle bulk and slow fiber type groupings, providing evidence that physical activity maintains slow motoneurons which reinnervate muscle fibers. Further, accelerated muscle atrophy/degeneration occurs with irreversible Conus and Cauda Equina syndrome, a spinal cord injury in which the human leg muscles may be permanently disconnected from the nervous system with complete loss of muscle fibers within 5-8 years. We used histological morphometry and Muscle Color Computed Tomography to evaluate muscle from these peculiar persons and reveal that contraction produced by home-based Functional Electrical Stimulation (h-bFES) recovers muscle size and function which is reversed if h-bFES is discontinued. FES also reverses muscle atrophy in sedentary seniors and modulates mitochondria in horse muscles. All together these observations indicate that FES modifies muscle fibers by increasing contractions per day. Thus, FES should be considered in critical care units, rehabilitation centers and nursing facilities when patients are unable or reluctant to exercise.

  11. An Objective Functional Characterisation of Head Movement Impairment in Individuals with Neck Muscle Weakness Due to Amyotrophic Lateral Sclerosis

    PubMed Central

    Pancani, Silvia; Tindale, Wendy; Shaw, Pamela J.

    2017-01-01

    Background Neck muscle weakness and head drop are well recognised in patients with Amyotrophic lateral sclerosis (ALS), but an objective characterisation of the consequent head movement impairment is lacking. The aim of this study was to quantitatively characterise head movements in ALS compared to aged matched controls. Methods We evaluated two groups, one of thirteen patients with ALS and one of thirteen age-matched controls, during the execution of a series of controlled head movements, performed while wearing two inertial sensors attached on the forehead and sternum, respectively. We quantified the differences between the two groups from the sensor data using indices of velocity, smoothness and movement coupling (intended as a measure of undesired out of plane movements). Findings Results confirmed a general limitation in the ability of the ALS patients to perform and control head movements. High inter-patient variability was observed due to a wide range of observed functional impairment levels. The ability to extend the head backward and flex it laterally were the most compromised, with significantly lower angular velocity (P < 0.05, Cohen’s d > 0.8), reduced smoothness and greater presence of coupled movements with respect to the controls. A significant reduction of angular velocity (P < 0.05, Cohen’s d > 0.8) in extension, axial rotation and lateral flexion was observed when patients were asked to perform the movements as fast as possible. Interpretation This pilot study is the first study providing a functional objective quantification of head movements in ALS. Further work involving different body areas and correlation with existing methods of evaluating neuromuscular function, such as dynamometry and EMG, is needed to explore the use of this approach as a marker of disease progression in ALS. PMID:28068376

  12. Elicitability of muscle cramps in different leg and foot muscles.

    PubMed

    Minetto, Marco Alessandro; Botter, Alberto

    2009-10-01

    To explore the efficacy of muscle motor point stimulation in eliciting muscle cramps, 11 subjects underwent eight sessions of electrical stimulation of the following muscles bilaterally: abductor hallucis flexor hallucis brevis, and both heads of the gastrocnemius muscles. Bursts of 150 square wave stimuli (duration: 152 micros; current intensity: 30% supramaximal) were applied. The stimulation frequency was increased from 4 pulses per second (pps) at increments of 2 pps until a cramp was induced. The number of cramps that could be elicited was smaller in flexor hallucis brevis than in abductor hallucis (16 vs. 22 out of 22 trials each; P < 0.05) and in the lateral gastrocnemius than in the medial gastrocnemius (5 vs. 20 out of 22 trials each; P < 0.0001). We show that leg and foot muscles have different cramp susceptibility, and the intermuscle variability in the elicitability profile for electrically induced cramps supports the use of the proposed method for cramp research.

  13. Acute motor and sensory axonal neuropathy (AMSAN) in a 15-year-old boy presenting with severe pain and distal muscle weakness.

    PubMed

    Rostásy, K M; Huppke, P; Beckers, B; Brockmann, K; Degenhardt, V; Wesche, B; König, F; Gärtner, J

    2005-08-01

    Acute motor and sensory axonal neuropathy (AMSAN) is a recently described subtype of Guillain-Barré syndrome characterized by acute onset of distal weakness, loss of deep tendon reflexes and sensory symptoms. Electrophysiological studies show mildly reduced nerve conduction velocities combined with a marked reduction of muscle action and sensory nerve action potentials. Here, we report a 15-year-old boy who suffered from severe burning and knife-like pain that increased over a period of three months and resulted in a disrupted sleep pattern and suicidal intentions as well as marked loss of weight. In addition, he developed muscle weakness in his hands and feet. Neurophysiological and histopathological studies revealed AMSAN. Marked improvement of his condition was achieved by treatment with intravenous immunoglobulins, high-dose methylprednisolone, and a combination of gabapentin, antidepressants, and an oral morphine.

  14. Facial-muscle weakness, speech disorders and dysphagia are common in patients with classic infantile Pompe disease treated with enzyme therapy.

    PubMed

    van Gelder, C M; van Capelle, C I; Ebbink, B J; Moor-van Nugteren, I; van den Hout, J M P; Hakkesteegt, M M; van Doorn, P A; de Coo, I F M; Reuser, A J J; de Gier, H H W; van der Ploeg, A T

    2012-05-01

    Classic infantile Pompe disease is an inherited generalized glycogen storage disorder caused by deficiency of lysosomal acid α-glucosidase. If left untreated, patients die before one year of age. Although enzyme-replacement therapy (ERT) has significantly prolonged lifespan, it has also revealed new aspects of the disease. For up to 11 years, we investigated the frequency and consequences of facial-muscle weakness, speech disorders and dysphagia in long-term survivors. Sequential photographs were used to determine the timing and severity of facial-muscle weakness. Using standardized articulation tests and fibreoptic endoscopic evaluation of swallowing, we investigated speech and swallowing function in a subset of patients. This study included 11 patients with classic infantile Pompe disease. Median age at the start of ERT was 2.4 months (range 0.1-8.3 months), and median age at the end of the study was 4.3 years (range 7.7 months -12.2 years). All patients developed facial-muscle weakness before the age of 15 months. Speech was studied in four patients. Articulation was disordered, with hypernasal resonance and reduced speech intelligibility in all four. Swallowing function was studied in six patients, the most important findings being ineffective swallowing with residues of food (5/6), penetration or aspiration (3/6), and reduced pharyngeal and/or laryngeal sensibility (2/6). We conclude that facial-muscle weakness, speech disorders and dysphagia are common in long-term survivors receiving ERT for classic infantile Pompe disease. To improve speech and reduce the risk for aspiration, early treatment by a speech therapist and regular swallowing assessments are recommended.

  15. The Evolution of and Risk Factors for Neck Muscle Atrophy and Weakness in Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy: A Retrospective Study in an Endemic Area.

    PubMed

    Zhang, Lu-Lu; Mao, Yan-Ping; Zhou, Guan-Qun; Tang, Ling-Long; Qi, Zhen-Yu; Lin, Li; Yao, Ji-Jin; Ma, Jun; Lin, Ai-Hua; Sun, Ying

    2015-08-01

    The aim of this study was to investigate the evolution of sternocleidomastoid muscle (SCM) atrophy in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT), and the relationship between SCM atrophy and neck weakness.Data were retrospectively analyzed from 223 biopsy-proven NPC patients with no distant metastasis who underwent IMRT with or without chemotherapy. The volume of SCM was measured on pretreatment magnetic resonance imaging (MRI), and MRIs were conducted 1, 2, and 3 years after the completion of IMRT. Change in SCM volume was calculated and classified using the late effects of normal tissues-subjective, objective, management, and analytic system. The grade of neck muscle weakness, classified by the Common Terminology Criteria for Adverse Events V 3.0, was measured 3 years after the completion of IMRT.The average SCM atrophy ratio was -10.97%, -18.65%, and -22.25% at 1, 2, and 3 years postirradiation, respectively. Multivariate analysis indicated N stage and the length of time after IMRT were independent prognostic variables. There were significant associations between the degree of SCM atrophy and neck weakness.Radical IMRT can cause significant SCM atrophy in NPC patients. A more advanced N stage was associated with more severe SCM atrophy, but no difference was observed between N2 and N3. SCM atrophy progresses over time during the 3 years following IMRT. Grade of SCM atrophy is significantly associated with neck weakness.

  16. The Evolution of and Risk Factors for Neck Muscle Atrophy and Weakness in Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy

    PubMed Central

    Zhang, Lu-Lu; Mao, Yan-Ping; Zhou, Guan-Qun; Tang, Ling-Long; Qi, Zhen-Yu; Lin, Li; Yao, Ji-Jin; Ma, Jun; Lin, Ai-Hua; Sun, Ying

    2015-01-01

    Abstract The aim of this study was to investigate the evolution of sternocleidomastoid muscle (SCM) atrophy in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT), and the relationship between SCM atrophy and neck weakness. Data were retrospectively analyzed from 223 biopsy-proven NPC patients with no distant metastasis who underwent IMRT with or without chemotherapy. The volume of SCM was measured on pretreatment magnetic resonance imaging (MRI), and MRIs were conducted 1, 2, and 3 years after the completion of IMRT. Change in SCM volume was calculated and classified using the late effects of normal tissues–subjective, objective, management, and analytic system. The grade of neck muscle weakness, classified by the Common Terminology Criteria for Adverse Events V 3.0, was measured 3 years after the completion of IMRT. The average SCM atrophy ratio was −10.97%, −18.65%, and −22.25% at 1, 2, and 3 years postirradiation, respectively. Multivariate analysis indicated N stage and the length of time after IMRT were independent prognostic variables. There were significant associations between the degree of SCM atrophy and neck weakness. Radical IMRT can cause significant SCM atrophy in NPC patients. A more advanced N stage was associated with more severe SCM atrophy, but no difference was observed between N2 and N3. SCM atrophy progresses over time during the 3 years following IMRT. Grade of SCM atrophy is significantly associated with neck weakness. PMID:26252307

  17. Bone Mineral Density and Fatty Degeneration of Thigh Muscles Measured by Computed Tomography in Hip Fracture Patients

    PubMed Central

    Hahn, Myung Hoon

    2016-01-01

    Background Recently, as an independent fracture factor from Bone mineral density (BMD), muscle weakness due to the fatty degeneration of thigh muscles have been attracting attentions as causes of hip fracture. The purpose of this study is to investigate the correlation between the body composition and BMD and fatty degeneration of thigh muscles of the female patients over 65 years old with osteoporotic hip fracture. Methods This study was conducted with 178 female osteoporotic hip fracture patients. Total hip BMD was measured using dual energy X-ray absorptiometry. Cross-sectional area (CSA), cross-sectional muscle area (CSmA), muscle attenuation coefficient (MAC), and intramuscular adipose tissue (IMAT) of gluteus maximus, hip abductors, quadriceps and hamstring muscle were measured with computed tomography. Normalized IMAT (nIMAT) was calculated by dividing the fat area in the muscle into the size of each muscle. The correlation between each measurement is examined then the differences between the intertrochanteric fracture group and the femoral neck fracture group were analyzed. Results CSmA and MAC of quadriceps were the largest and nIMAT was the lowest. CSA and CSmA of the four muscles showed a statistically significant positive correlation with weight, height, body mass index (BMI), and BMD. MAC of 2 gluteal muscles was positively correlated with weight, BMI and BMD. nIMAT of all four muscles was positively correlation with weight and BMI but nIMAT of 2 mid-thigh muscles was positively correlation with BMD. Conclusions Muscle size and fatty degeneration in the thigh muscles were most positively correlated with the body weight. BMD was positively correlation with CSA and CSmA of all thigh muscles, and MAC of 2 gluteal muscles and fatty degeneration of 2 mid-thigh muscles. There was no statistically significant difference in the size of the femoral muscle and the degree of fatty degeneration between the two fracture groups. PMID:27965943

  18. Muscle weakness and atrophy are associated with decreased regenerative capacity and changes in mTOR signaling in skeletal muscles of venerable (18-24-month-old) dystrophic mdx mice.

    PubMed

    Mouisel, E; Vignaud, A; Hourdé, C; Butler-Browne, G; Ferry, A

    2010-06-01

    The muscles of mdx mice progressively deteriorate with age. We wanted to know whether this is associated with a decrease in regenerative capacity and/or changes in the mammalian target of rapamycin complex (mTOR) signaling pathway. Muscles of mdx mice aged 5 weeks, 5, 12, and 18-24 months were studied. Maximal force and muscle weight of the older mice were decreased as compared to younger adult mice. Activation of the mTOR signaling pathway, i.e., phosphorylation of Akt (also known as protein kinase B) and ribosomal protein S6 was also reduced in the older mice. Moreover, 14 days after cardiotoxin injury the degree of recovery of maximal force and muscle weight were less in the older mice. In contrast to younger mice, there was also activation of the mTOR pathway during regeneration in the older mice. Progressive muscle weakness and atrophy in mdx mouse muscle is associated with a decline in regenerative potential and changes in activation of the mTOR signaling pathway.

  19. Cardiac arrhythmia and late-onset muscle weakness caused by a myofibrillar myopathy with unusual histopathological features due to a novel missense mutation in FLNC.

    PubMed

    Avila-Smirnow, D; Gueneau, L; Batonnet-Pichon, S; Delort, F; Bécane, H-M; Claeys, K; Beuvin, M; Goudeau, B; Jais, J-P; Nelson, I; Richard, P; Ben Yaou, R; Romero, N B; Wahbi, K; Mathis, S; Voit, T; Furst, D; van der Ven, P; Gil, R; Vicart, P; Fardeau, M; Bonne, G; Behin, A

    2016-10-01

    Myofibrillar myopathies (MFM) are mostly adult-onset diseases characterized by progressive morphological alterations of the muscle fibers beginning in the Z-disk and the presence of protein aggregates in the sarcoplasm. They are mostly caused by mutations in different genes that encode Z-disk proteins, including DES, CRYAB, LDB3, MYOT, FLNC and BAG3. A large family of French origin, presenting an autosomal dominant pattern, characterized by cardiac arrhythmia associated to late-onset muscle weakness, was evaluated to clarify clinical, morphological and genetic diagnosis. Muscle weakness began during adult life (over 30 years of age), and had a proximal distribution. Histology showed clear signs of a myofibrillar myopathy, but with unusual, large inclusions. Subsequently, genetic testing was performed in MFM genes available for screening at the time of clinical/histological diagnosis, and desmin (DES), αB-crystallin (CRYAB), myotilin (MYOT) and ZASP (LDB3), were excluded. LMNA gene screening found the p.R296C variant which did not co-segregate with the disease. Genome wide scan revealed linkage to 7q.32, containing the FLNC gene. FLNC direct sequencing revealed a heterozygous c.3646T>A p.Tyr1216Asn change, co-segregating with the disease, in a highly conserved amino acid of the protein. Normal filamin C levels were detected by Western-blot analysis in patient muscle biopsies and expression of the mutant protein in NIH3T3 showed filamin C aggregates. This is an original FLNC mutation in a MFM family with an atypical clinical and histopathological presentation, given the presence of significantly focal lesions and prominent sarcoplasmic masses in muscle biopsies and the constant heart involvement preceding significantly the onset of the myopathy. Though a rare etiology, FLNC gene should not be excluded in early-onset arrhythmia, even in the absence of myopathy, which occurs later in the disease course.

  20. De Quervain disease caused by abductor pollicis longus tenosynovitis: a report of three cases.

    PubMed

    Maruyama, Masahiro; Takahara, Masatoshi; Kikuchi, Noriaki; Ito, Kazuo; Watanabe, Tadayoshi; Ogino, Toshihiko

    2009-01-01

    De Quervain disease is caused by a stenosing tenosynovitis in the first dorsal compartment, and the main aetiology is extensor pollicis brevis (EPB) tenosynovitis. We encountered three cases in which EPB tenosynovitis was absent and abductor pollicis longus (APL) tenosynovitis was confirmed during operation. In the treatment of de Quervain disease, APL tenosynovitis should be paid as much attention as EPB tenosynovitis.

  1. Laser Posterior Cordotomy: Is it a Good Choice in Treating Bilateral Vocal Fold Abductor Paralysis?

    PubMed Central

    Khalil, Mahmoud A; Abdel Tawab, Hazem M

    2014-01-01

    BACKGROUND Bilateral abductor vocal fold paralysis can lead to respiratory distress and dyspnea. OBJECTIVES To assess the efficacy of CO2 laser unilateral posterior cordotomy in cases with bilateral abductor paralysis as regards improvement of dyspnea with preservation of satisfactory voice and swallowing after the operation. METHODS A prospective study was done on 18 patients with bilateral abductor vocal fold paralysis (10 females and 8 males) from November 2010 to December 2012 with their ages ranging from 32 to 64 years. RESULTS All patients showed improvement of dyspnea after the operation, most of the patients suffered from mild to moderate dyspnea in the immediate post-operative period, and two patients needed another intervention to solve it. All the patients had satisfactory results of their voice after the operation, and one patient only suffered from temporary aspiration. CONCLUSION Unilateral CO2 laser posterior cordotomy is an easy and effective procedure to solve the dyspnea after bilateral vocal fold abductor paralysis without aspiration or significant voice alteration. PMID:25057244

  2. The effect of thin filament activation on the attachment of weak binding cross-bridges: A two-dimensional x-ray diffraction study on single muscle fibers.

    PubMed

    Kraft, T; Xu, S; Brenner, B; Yu, L C

    1999-03-01

    To study possible structural changes in weak cross-bridge attachment to actin upon activation of the thin filament, two-dimensional (2D) x-ray diffraction patterns of skinned fibers from rabbit psoas muscle were recorded at low and high calcium concentration in the presence of saturating concentrations of MgATPgammaS, a nucleotide analog for weak binding states. We also studied 2D x-ray diffraction patterns recorded under relaxing conditions at an ionic strength above and below 50 mM, because it had been proposed from solution studies that reducing ionic strength below 50 mM also induces activation of the thin filament. For this project a novel preparation had to be established that allows recording of 2D x-ray diffraction patterns from single muscle fibers instead of natural fiber bundles. This was required to minimize substrate depletion or product accumulation within the fibers. When the calcium concentration was raised, the diffraction patterns recorded with MgATPgammaS revealed small changes in meridional reflections and layer line intensities that could be attributed in part to the effects of calcium binding to the thin filament (increase in I380, decrease in first actin layer line intensity, increase in I59) and in part to small structural changes of weakly attached cross-bridges (e.g., increase in I143 and I72). Calcium-induced small-scale structural rearrangements of cross-bridges weakly attached to actin in the presence of MgATPgammaS are consistent with our previous observation of reduced rate constants for attachment and detachment of cross-bridges with MgATPgammaS at high calcium. Yet, no evidence was found that weakly attached cross-bridges change their mode of attachment toward a stereospecific conformation when the actin filament is activated by adding calcium. Similarly, reducing ionic strength to less than 50 mM does not induce a transition from nonstereospecific to stereospecific attachment.

  3. Effects of Multi-modal Physiotherapy, Including Hip Abductor Strengthening, in Patients with Iliotibial Band Friction Syndrome

    PubMed Central

    Beers, Amanda; Ryan, Michael; Kasubuchi, Zenya; Fraser, Scott

    2008-01-01

    Purpose: The purposes of this study were to quantitatively examine hip abductor strength in patients presenting with iliotibial band friction syndrome (ITBFS) and to determine whether a multi-modal physiotherapy approach, including hip abductor strengthening, might play a role in recovery. Method: Our observational, pretest–posttest study is one of the first prospective studies in this area. Patients presenting to physiotherapy with unilateral ITBFS were recruited to participate. Participants followed a 6-week rehabilitation programme designed to strengthen hip abductors; strength was measured every 2 weeks using a hand-held dynamometer and compared bilaterally. Results: Sixteen subjects (five men, 11 women) aged 20 to 53 years participated. All but 2 reported running as one of their main physical activities. A trend toward a significant difference in hip abductor strength was found between the injured and uninjured sides at baseline, but this difference disappeared by 6 weeks. Hip abductor strength was significantly related to physical function at weeks 2, 4, and 6. Nine subjects were discharged from physiotherapy after the 6-week period, while the other 7 subjects continued attending for up to 5 months. Conclusions: Hip abductor strengthening appeared to be beneficial in the treatment of ITBFS, but further research on the use of hip abductor strengthening for treatment and prevention of ITBFS is needed. PMID:20145781

  4. Muscle weakness in myotonic dystrophy associated with misregulated splicing and altered gating of CaV1.1 calcium channel

    PubMed Central

    Tang, Zhen Zhi; Yarotskyy, Viktor; Wei, Lan; Sobczak, Krzysztof; Nakamori, Masayuki; Eichinger, Katy; Moxley, Richard T.; Dirksen, Robert T.; Thornton, Charles A.

    2012-01-01

    Myotonic dystrophy type 1 and type 2 (DM1 and DM2) are genetic diseases in which mutant transcripts containing expanded CUG or CCUG repeats cause cellular dysfunction by altering the processing or metabolism of specific mRNAs and miRNAs. The toxic effects of mutant RNA are mediated partly through effects on proteins that regulate alternative splicing. Here we show that alternative splicing of exon 29 (E29) of CaV1.1, a calcium channel that controls skeletal muscle excitation–contraction coupling, is markedly repressed in DM1 and DM2. The extent of E29 skipping correlated with severity of weakness in tibialis anterior muscle of DM1 patients. Two splicing factors previously implicated in DM1, MBNL1 and CUGBP1, participated in the regulation of E29 splicing. In muscle fibers of wild-type mice, the CaV1.1 channel conductance and voltage sensitivity were increased by splice-shifting oligonucleotides that induce E29 skipping. In contrast to human DM1, expression of CUG-expanded RNA caused only a modest increase in E29 skipping in mice. However, forced skipping of E29 in these mice, to levels approaching those observed in human DM1, aggravated the muscle pathology as evidenced by increased central nucleation. Together, these results indicate that DM-associated splicing defects alter CaV1.1 function, with potential for exacerbation of myopathy. PMID:22140091

  5. Description and scaling of pectoral muscles in ictalurid catfishes.

    PubMed

    Miano, Joseph Paul; Loesser-Casey, Kathryn E; Fine, Michael L

    2013-04-01

    The pectoral spine of catfishes is an antipredator adaptation that can be bound, locked, and rubbed against the cleithrum to produce stridulation sounds. We describe muscle morphology of the pectoral spines and rays in six species in four genera of North American ictalurid catfishes. Since homologies of catfish pectoral muscles have not been universally accepted, we designate them functionally as the spine abductor and adductor and the arrector dorsalis and ventralis. The four muscles of the remaining pectoral rays are the superficial and deep (profundal) abductors and adductors. The large spine abductor and spine adductor are responsible for large amplitude movements, and the smaller arrector dorsalis and arrector ventralis have more specialized functions, that is, spine elevation and depression, respectively, although they also contribute to spine abduction. Three of the four spine muscles were pennate (the abductor and two arrectors), the spine adductor can be pennate or parallel, and ray muscles have parallel fibers. Insertions of pectoral muscles are similar across species, but there is a shift of origins in some muscles, particularly of the superficial abductor of the pectoral rays, which assumes a midline position in Ictalurus and increasingly more lateral placement in Ameiurus (one quarter way out from the midline), and Pylodictis and Noturus (half way out). Coincident with this lateral shift, the attachments of the hypaxial muscle to the ventral girdle become more robust. Comparison with its sister group supports the midline position as basal and lateral migration as derived. The muscles of the pectoral spine are heavier than muscles of the remaining rays in all species but the flathead, supporting the importance of specialized spine functions above typical movement. Further, spine muscles were larger than ray muscles in all species but the flathead catfish, which lives in water with the fastest currents.

  6. The effect of thin filament activation on the attachment of weak binding cross-bridges: A two-dimensional x-ray diffraction study on single muscle fibers.

    PubMed Central

    Kraft, T; Xu, S; Brenner, B; Yu, L C

    1999-01-01

    To study possible structural changes in weak cross-bridge attachment to actin upon activation of the thin filament, two-dimensional (2D) x-ray diffraction patterns of skinned fibers from rabbit psoas muscle were recorded at low and high calcium concentration in the presence of saturating concentrations of MgATPgammaS, a nucleotide analog for weak binding states. We also studied 2D x-ray diffraction patterns recorded under relaxing conditions at an ionic strength above and below 50 mM, because it had been proposed from solution studies that reducing ionic strength below 50 mM also induces activation of the thin filament. For this project a novel preparation had to be established that allows recording of 2D x-ray diffraction patterns from single muscle fibers instead of natural fiber bundles. This was required to minimize substrate depletion or product accumulation within the fibers. When the calcium concentration was raised, the diffraction patterns recorded with MgATPgammaS revealed small changes in meridional reflections and layer line intensities that could be attributed in part to the effects of calcium binding to the thin filament (increase in I380, decrease in first actin layer line intensity, increase in I59) and in part to small structural changes of weakly attached cross-bridges (e.g., increase in I143 and I72). Calcium-induced small-scale structural rearrangements of cross-bridges weakly attached to actin in the presence of MgATPgammaS are consistent with our previous observation of reduced rate constants for attachment and detachment of cross-bridges with MgATPgammaS at high calcium. Yet, no evidence was found that weakly attached cross-bridges change their mode of attachment toward a stereospecific conformation when the actin filament is activated by adding calcium. Similarly, reducing ionic strength to less than 50 mM does not induce a transition from nonstereospecific to stereospecific attachment. PMID:10049330

  7. Differential Modulation of Intracortical Inhibition in Human Motor Cortex during Selective Activation of an Intrinsic Hand Muscle

    PubMed Central

    Zoghi, Maryam; Pearce, Sophie L; Nordstrom, Michael A

    2003-01-01

    Paired-pulse transcranial magnetic stimulation (TMS) was used to assess the effectiveness of intracortical inhibition (ICI) acting on corticospinal neurons controlling three intrinsic hand muscles in humans. We hypothesised that the suppression of ICI with selective activation of a muscle would be restricted to corticospinal neurons controlling the muscle targeted for activation. Surface EMG was recorded from abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the left hand. Subjects were tested at rest and during weak selective activation of APB or ADM, while they attempted to keep the other muscles relaxed using visual feedback. Paired-pulse TMS was applied with a circular coil oriented to produce antero-posterior (AP) current flow in the right motor cortex (to preferentially evoke I3 waves in corticospinal neurons) and with postero-anterior (PA) currents (to preferentially evoke I1 waves). Paired-pulse TMS was less effective in suppressing the muscle evoked potential (MEP) when the muscle was targeted for selective activation, with both AP and PA stimulation. The mechanism for this includes effects on late I waves, as it was evident with a weak AP test TMS pulse that elicited negligible I1 waves in corticospinal neurons. ICI circuits activated by TMS, which exert their effects on late I waves but do not affect I1 waves, are strongly implicated in this modulation. With AP stimulation, paired-pulse inhibition was not significantly altered for corticospinal neurons controlling other muscles of the same hand which were required to be inactive during the selective activation task. This differential modulation was not seen with PA stimulation, which preferentially activates I1 waves and evokes a MEP that is less influenced by ICI. The observations with AP stimulation suggest that selective activation of a hand muscle is accompanied by a selective suppression of ICI effects on the corticospinal neurons controlling

  8. Antagonism of botulinum toxin-induced muscle weakness by aminopyridines in rat phrenic nerve-hemidiaphragm preparations

    SciTech Connect

    Adler, M.; Scovill, J.; Deshpande, S.S.

    1993-05-13

    The effects of the potassium channel inhibitor and putative botulinum toxin antagonists 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP) were investigated in vitro on the contractile and electrophysiological properties of rat diaphragm muscle. In the presence of 300 pM botulinum toxin A (BoTx A), twitches elicited by supramaximal nerve stimulation (0. 1 Hz) were reduced by over 80% in 3 hr. The time to block decreased with increases in temperature, toxin concentration and stimulation frequency. Addition of 4-AP or 3,4-DAP led to a prompt reversal of the BoTx A-induced depression of twitch tension. This reversal was concentration-dependent such that, in the presence of 1 mM 4-AP, reversal of the BoTx A-induced blockade was complete in 6.7 min. The beneficial effect of the APs were well maintained and persisted for up to 6 hr after addition. Application of 1 microns M neostigmine 1 hr after 3,4-DAP produced a further potentiation of twitch tensions, but this action lasted for < 5 min and led to the appearance of tetanic fade during repetitive stimulation. It is concluded that the APs are of benefit in antagonizing the muscle paralysis following exposure to botulinum toxin. Co-application of neostigmine, however, appears to confer no additional benefit.

  9. Pyruvate dehydrogenase-E1α deficiency presenting as recurrent acute proximal muscle weakness of upper and lower extremities in an 8-year-old boy.

    PubMed

    Kara, Bülent; Genç, Hülya Maraş; Uyur-Yalçın, Emek; Sakarya-Güneş, Ayfer; Topçu, Uğur; Mülayim, Serap; Ceylaner, Serdar

    2017-01-01

    The mitochondrial pyruvate dehydrogenase enzyme complex (PDHC) plays an important role in aerobic energy metabolism and acid-base equilibrium. PDHC contains of 5 enzymes, 3 catalytic (E1, E2, E3) and 2 regulatory, as well as 3 cofactors and an additional protein (E3-binding protein) encoded by nuclear genes. The clinical presentation of PDHC deficiency ranges from fatal neonatal lactic acidosis to chronic neurologic dysfunction without lactic acidosis. Paroxysmal neurologic problems such as intermittent ataxia, episodic weakness, exercise-induced dystonia and recurrent demyelination may also be seen although they are rare. Here, we present an 8-year-old boy complaining of acute proximal muscle weakness of upper and lower extremities with normal mental status. He had a history of Guillain-Barré-like syndrome at the age of 2 years. Electrophysiologic studies showed sensorial polyneuropathy findings in the first attack and sensorimotor axonal polyneuropathy findings in the last attack. The genetic analysis revealed a previously reported hemizygote novel mutation of the PDHA1 gene (p.A353T/c.1057G > A), which encodes the E1α subunit of PDHC. Thiamine was ordered (15 mg/kg/day), dietary carbohydrates were restricted and clinical findings improved in a few weeks. This rare phenotype of PDHC deficiency is discussed.

  10. Both poor cardiorespiratory and weak muscle fitness are related to a high concentration of oxidized low-density lipoprotein lipids.

    PubMed

    Kosola, J; Ahotupa, M; Kyröläinen, H; Santtila, M; Vasankari, T

    2012-12-01

    Good physical fitness is associated with favorable serum lipids. Oxidized low-density lipoprotein (ox-LDL) could be even more atherogenic than serum lipids. We studied the association of ox-LDL and serum lipids with physical fitness. Healthy young (mean age 25 years) men (n=846) underwent maximal oxygen uptake (VO(2max)) and muscle fitness index (MFI) tests and completed a leisure-time physical activity (LTPA) questionnaire. Age (ANCOVA1), age+waist circumference+systolic blood pressure+fasting blood glucose+smoking (ANCOVA3) were used as covariates. The groups with the lowest VO(2max), MFI and LTPA had 23%, 16% and 8% higher concentrations of ox-LDL than the groups with the highest VO(2max) (P<0.0001), MFI (P=0.022) and LTPA (P=0.039) groups, respectively. Subjects with poor fitness (low VO(2max) or low MFI) or low LTPA had elevated levels of ox-LDL/high-density lipoprotein (HDL)-cholesterol, total cholesterol, LDL-cholesterol, triglycerides and a low level of HDL-cholesterol (ANCOVA1, in all, P<0.05). Furthermore, low VO(2max) is associated with a high level of ox-LDL/HDL-cholesterol and triglycerides, and with a low level of HDL-cholesterol (ANCOVA3, in all, P<0.05). Also, subjects with low LTPA had a high ratio of ox-LDL/HDL-cholesterol (ANCOVA1, P=0.001). In conclusion, both poor fitness (both low VO(2max) and low MFI) and low LTPA are associated with a higher concentration of ox-LDL lipids and serum lipids, which may indicate a higher risk for atherosclerosis.

  11. Infraspinatus muscle atrophy from suprascapular nerve compression.

    PubMed

    Cordova, Christopher B; Owens, Brett D

    2014-02-01

    Muscle weakness without pain may signal a nerve compression injury. Because these injuries should be identified and treated early to prevent permanent muscle weakness and atrophy, providers should consider suprascapular nerve compression in patients with shoulder muscle weakness.

  12. Anatomic Variations of the First Extensor Compartment and Abductor Pollicis Longus Tendon in Trapeziometacarpal Arthritis

    PubMed Central

    Opreanu, Razvan C.; Wechter, John; Tabbaa, Hazem; Kepros, John P.; Baulch, Michelle; Xie, Yan; Lackey, Wendy

    2009-01-01

    Anatomic variation of the trapeziometacarpal joint stabilizing structures is one of the concepts proposed to explain the pathogenesis of trapeziometacarpal arthritis. We undertook this study to test the hypothesis that septation of the first extensor compartment or variation of the abductor pollicis longus (APL) tendon (supernumerary insertions) are more frequently associated with the progression or severity of trapeziometacarpal arthritis. Septation within the first extensor compartment was significantly associated with trapeziometacarpal arthritis (p = 0.013), whereas supernumerary APL insertions (trapezium or thenar) did not reveal a significant association (p = 0.811 and p = 0.937, respectively). The results of this study do not support a role for variations of APL tendon insertions in trapeziometacarpal arthritis. Yet, the presence of septation within the first extensor compartment may play an important role in the pathogenesis of trapeziometacarpal arthritis. PMID:19834771

  13. Difference in Cortical Relay Time Between Intrinsic Muscles of Dominant and Nondominant Hands.

    PubMed

    Kirimoto, Hikari; Tamaki, Hiroyuki; Onishi, Hideaki

    2016-12-09

    The authors aimed to calculate and compare cortical relay time (CRT) between intrinsic hand muscles and between homonymous muscles of dominant and nondominant hands. The participants comprised 22 healthy volunteers. The CRT for long-latency reflexes (LLRs) was calculated by subtracting the peak latency of somatosensory evoked potentials of component N20 and the onset latency of motor evoked potentials from the onset latency of LLRs. CRT was significantly shorter for the first dorsal interosseous muscle than for the abductor pollicis brevis muscle, regardless of hand dominance. CRT for the abductor pollicis brevis muscle was significantly shorter in the dominant hand than in the nondominant hand. Evaluation of CRT for intrinsic muscles might be beneficial in the understanding of individuated finger functions.

  14. Inter-Tester Reliability and Precision of Manual Muscle Testing and Hand-Held Dynamometry in Lower Limb Muscles of Children with Spina Bifida

    ERIC Educational Resources Information Center

    Mahony, Kate; Hunt, Adrienne; Daley, Deborah; Sims, Susan; Adams, Roger

    2009-01-01

    Reliability and measurement precision of manual muscle testing (MMT) and hand-held dynamometry (HHD) were compared for children with spina bifida. Strength measures were obtained of the hip flexors, hip abductors, and knee extensors of 20 children (10 males, 10 females; mean age 9 years 10 months; range: 5 to 15 years) by two experienced physical…

  15. Anatomical variation of abductor pollicis longus in Indian population: A cadaveric study

    PubMed Central

    Tewari, Jerina; Mishra, Pravash Ranjan; Tripathy, Sujit Kumar

    2015-01-01

    Background: Many authors have reported the anatomical variation of abductor pollicis longus (APL) around the wrist and its association with de Quervain tenosynovitis (DQT), first carpo-metacarpal arthritis, and trapezio-metacarpal subluxation. From Indian subcontinent, there is only one original article and a few case reports on the variability of APL tendon insertion. Materials and Methods: Fifty formaldehyde preserved cadaveric wrists were dissected to look for the anatomical variation of APL in the Indian population. Results: The APL was found with single tendon in 2, double in 31, triple in 8, and quadruple in 8 extremities. A maximum of 6 tendon-slips were found in one cadaveric wrist. In all hands, the APL had at least one attachment to first metacarpal bone and in 46 hands (92%), there was second insertion to the trapezium bone. Of all tendon-slips of APL (n = 126), 44% of tendons (68 tendons) were inserted into the base of the first metacarpal bone. This was followed by the insertion into the trapezium in 42% tendons (52 tendons). Conclusion: Bi-tendinous APL is commonly observed on the dorsal compartment of the wrist in Indian population and these tendon-slips are commonly attached to the first metacarpal base and trapezium. This variation must be understood by the Indian Orthopedic surgeons as the response to treatment of DQT and reason for first carpo-metacarpal arthritis can be dependent on this anatomical variation. PMID:26538762

  16. Shoulder muscle activity and function in common shoulder rehabilitation exercises.

    PubMed

    Escamilla, Rafael F; Yamashiro, Kyle; Paulos, Lonnie; Andrews, James R

    2009-01-01

    The rotator cuff performs multiple functions during shoulder exercises, including glenohumeral abduction, external rotation (ER) and internal rotation (IR). The rotator cuff also stabilizes the glenohumeral joint and controls humeral head translations. The infraspinatus and subscapularis have significant roles in scapular plane abduction (scaption), generating forces that are two to three times greater than supraspinatus force. However, the supraspinatus still remains a more effective shoulder abductor because of its more effective moment arm. Both the deltoids and rotator cuff provide significant abduction torque, with an estimated contribution up to 35-65% by the middle deltoid, 30% by the subscapularis, 25% by the supraspinatus, 10% by the infraspinatus and 2% by the anterior deltoid. During abduction, middle deltoid force has been estimated to be 434 N, followed by 323 N from the anterior deltoid, 283 N from the subscapularis, 205 N from the infraspinatus, and 117 N from the supraspinatus. These forces are generated not only to abduct the shoulder but also to stabilize the joint and neutralize the antagonistic effects of undesirable actions. Relatively high force from the rotator cuff not only helps abduct the shoulder but also neutralizes the superior directed force generated by the deltoids at lower abduction angles. Even though anterior deltoid force is relatively high, its ability to abduct the shoulder is low due to a very small moment arm, especially at low abduction angles. The deltoids are more effective abductors at higher abduction angles while the rotator cuff muscles are more effective abductors at lower abduction angles. During maximum humeral elevation the scapula normally upwardly rotates 45-55 degrees, posterior tilts 20-40 degrees and externally rotates 15-35 degrees. The scapular muscles are important during humeral elevation because they cause these motions, especially the serratus anterior, which contributes to scapular upward rotation

  17. Surface electromyogram and muscle ultrasonography for detection of muscle fasciculations in pediatric peripheral neuropathy.

    PubMed

    Oguri, Masayoshi; Saito, Yoshiaki; Okazaki, Tetsuya; Matsumura, Wataru; Ohno, Koyo; Togawa, Masami; Fukuda, Chisako; Saito, Yuko; Nishino, Ichizo; Maegaki, Yoshihiro

    2017-03-16

    A 12-year-old girl presented with talipes equinus of both legs, attenuation of upper and lower limb tendon reflexes, thermal hyperalgesia, and reduction of vibratory sensation. On clinical examination, muscle twitches of fingers of both hands, as well as the abductor halluces and the dorsal interossei muscles of the right foot were observed. Nerve conduction velocity was significantly declined in the upper and lower extremities. Needle electromyography (EMG) was not performed; however, ultrasonography revealed repetitive, semi-regular muscle twitches lasting 0.2-0.4s, concomitant with muscle discharges on surface EMG in the right foot muscles. These findings were compatible with contraction fasciculation in muscles under chronic reinnervation. Nerve and muscle biopsies were suggestive of chronic motor, sensory, and autonomic neuropathy. This is the first case of pediatric peripheral neuropathy where muscle fasciculation was noninvasively identified by simultaneous surface EMG and ultrasonography.

  18. Quantitative Muscle Ultrasonography in Carpal Tunnel Syndrome

    PubMed Central

    2016-01-01

    Objective To assess the reliability of quantitative muscle ultrasonography (US) in healthy subjects and to evaluate the correlation between quantitative muscle US findings and electrodiagnostic study results in patients with carpal tunnel syndrome (CTS). The clinical significance of quantitative muscle US in CTS was also assessed. Methods Twenty patients with CTS and 20 age-matched healthy volunteers were recruited. All control and CTS subjects underwent a bilateral median and ulnar nerve conduction study (NCS) and quantitative muscle US. Transverse US images of the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) were obtained to measure muscle cross-sectional area (CSA), thickness, and echo intensity (EI). EI was determined using computer-assisted, grayscale analysis. Inter-rater and intra-rater reliability for quantitative muscle US in control subjects, and differences in muscle thickness, CSA, and EI between the CTS patient and control groups were analyzed. Relationships between quantitative US parameters and electrodiagnostic study results were evaluated. Results Quantitative muscle US had high inter-rater and intra-rater reliability in the control group. Muscle thickness and CSA were significantly decreased, and EI was significantly increased in the APB of the CTS group (all p<0.05). EI demonstrated a significant positive correlation with latency of the median motor and sensory NCS in CTS patients (p<0.05). Conclusion These findings suggest that quantitative muscle US parameters may be useful for detecting muscle changes in CTS. Further study involving patients with other neuromuscular diseases is needed to evaluate peripheral muscle change using quantitative muscle US. PMID:28119835

  19. Patterns of prior offending by child abductors: a comparison of fatal and non-fatal outcomes.

    PubMed

    Beasley, James Oliver; Hayne, Anita S; Beyer, Kristen; Cramer, Gary L; Berson, Sarah Bradley; Muirhead, Yvonne; Warren, Janet I

    2009-01-01

    Our study examines the prior offending of 750 individuals who are known to be responsible for the abduction of a child under the age of 18 years. The first group comprised of 311 offenders (42%) who had abducted a child that was later located alive (found alive, referred to as FA). The second group was comprised of 439 offenders (58%) who had abducted a child that was either found murdered or was still missing and presumed dead (found murdered, referred to as FM). While males perpetrated the majority of the abductions, women perpetrated 31 (10%) of the offenses in the FA group and 10 (2%) of the offenses in the FM group. The average number of prior offenses as reflected in the NCIC criminal history of each offender was seven with these occurring over an average of 12 years. Seventy-five percent of the offenders had prior arrests for an assortment of different crimes while 25% had no known criminal history, a finding that was consistent across both the FA and FM groups. Of those with a criminal history, 41% had been arrested for assault, 40% for larceny, 35% for burglary/breaking and entering, 33% for forcible sex offenses, 25% for drug/narcotic offenses, 21% for weapons law violations, 17% for motor vehicle thefts, 15% for robbery, and 14% for kidnapping. Our findings are congruent with the theme of criminal diversity among child abductors and argue against the specificity in offending that is often assumed with this type of sexual offender. This information is relevant to our understanding of the progression in criminal offending that is manifested by offenders who abduct children and will hopefully be used by law enforcement in helping to direct and focus their investigations.

  20. Results of Abductor Pollicis Longus Suspension Ligamentoplasty for Treatment of Advanced First Carpometacarpal Arthritis

    PubMed Central

    Lee, Hyun-Joo; Kim, Poong-Taek; Deslivia, Maria Florencia; Lee, Suk-Joong; Nam, Sang-Jin

    2015-01-01

    Background Suspension ligamentoplasty using abductor pollicis longus (APL) tendon without bone tunneling, was introduced as one of the techniques for treatment of advanced first carpometacarpal (CMC) arthritis. The purpose of this study was to evaluate the radiologic and clinical results of APL suspension ligamentoplasty. Methods The medical records of 19 patients who underwent APL suspension ligamentoplasty for advanced first CMC arthritis between January 2008 and May 2012 were reviewed retrospectively. The study included 13 female and 6 male patients, whose mean age was 62 years (range, 43 to 82 years). For clinical evaluation, we assessed the grip and pinch power, radial and volar abduction angle, thumb adduction (modified Kapandji index), including visual analogue scale (VAS) and Disabilities of the Arm, Shoulder and Hand (DASH) scores. Radiologic evaluation was performed using simple radiographs. Results The mean follow-up was 36 months (range, 19 to 73.7 months). Mean power improved from 18.3 to 27 kg for grip power, from 2.8 to 3.5 kg for tip pinch, and from 4.3 to 5.4 kg for power pinch. All patients showed decreased VAS from 7.2 to 1.7. Radial abduction improved from 71° preoperatively to 82° postoperatively. The modified Kapandji index showed improvement from 6 to 7.3, and mean DASH was improved from 41 to 17.8. The height of the space decreased from 10.8 to 7.1 mm. Only one case had a complication involving temporary sensory loss of the first dorsal web space, which resolved spontaneously. Conclusions The APL suspension ligamentoplasty for treatment of advanced first CMC arthritis yielded satisfactory functional results. PMID:26330961

  1. Proximal weakness of the extremities as main feature of amyloid myopathy.

    PubMed Central

    Jennekens, F G; Wokke, J H

    1987-01-01

    Two patients with muscle weakness caused by amyloid myopathy are described. Characteristic features such as pseudohypertrophy and abnormal firmness, and tumours of muscles were absent. It is suggested that muscle weakness in amyloid myopathy is caused by layers of amyloid covering muscle fibres. In middle aged or elderly patients with proximal muscle weakness the diagnosis of amyloid myopathy should be considered. Images PMID:3681315

  2. Reconditioning aging muscles.

    PubMed

    Kraus, H

    1978-06-01

    Weakness or stiffness of key posture muscles can cause much of the disability seen in elderly patients. Too much tension and too little exercise greatly increase the natural loss of muscular fitness with age. A systematic program of exercise, stressing relaxation and stretching of tight muscles and strenghthening of weak muscles, can improve physical fitness. The program must be tailored to the patient, starting with relaxation and gentle limbering exercises and proceeding ultimately to vigorous muscle-stretching exercises. Muscle aches and pain from tension and muscle imbalance are to be expected. Relaxation relieves tension pain, and strengthening weak muscles and stretching tight muscles will correct muscle imbalance. To prevent acute muscle spasm, the patient should avoid excessive exertion and increase exercise intensity gradually.

  3. Multiple muscle tear after fall on buttock-role of conservative management and exercise for early recovery and return to play

    PubMed Central

    Adhau, Rajesh; Angrish, Piyush; Ahuja, Ashok; Sandhu, Avtar Singh

    2014-01-01

    Summary Background: to describe role of alternative management as an approach to management and rehabilitation of multiple hip muscles tears by the use of 1 RM (Repetition Maximum) testing and hip muscle strengthening program along with the use of sports specific drills for rehabilitation and recovery. There is very limited literature describing multiple hip muscle tears and the conservative management of the same. 1RM testing and strengthening of hip muscles is an approach that is able to help in the return to sports of an athlete without surgical intervention. Methods: the patient, is a 21-year-old male hockey player who presented with pain right buttock, right lower leg and a limp on the right side while walking. Physical examination revealed a positive Trendelenburg sign both in stance and gait phase. Hip rotational movements showed a normal range of motion, there was a severe pain in the right buttock on movements which he described at 8/10 on VAS (Visual Analogue Scale). Strength assessment revealed weakness of the right hip flexors and extensors and also of the abductor and external hip rotator muscles. Treatment protocol followed was based on 1 RM testing of muscles and hip strengthening exercises and sports specific drills. Results: following the intervention, the patient reported pain at 0/10 VAS while doing all activities and also showed good muscle control with no limp. Conclusions: this highlights an alternative protocol for treating multiple hip muscle tears and illustrates the importance of 1 RM testing as a part of examination and sports medicine intervention. PMID:25332927

  4. THE CLINICAL, FUNCTIONAL AND BIOMECHANICAL PRESENTATION OF PATIENTS WITH SYMPTOMATIC HIP ABDUCTOR TENDON TEARS

    PubMed Central

    Retheesh, Theertha; Mutreja, Rinky; Janes, Gregory C.

    2016-01-01

    Background Hip abductor tendon (HAT) tearing is commonly implicated in greater trochanteric pain syndrome (GTPS), though limited information exists on the disability associated with this condition and specific presentation of these patients. Purpose To describe the clinical, functional and biomechanical presentation of patients with symptomatic HAT tears. Secondary purposes were to investigate the association between these clinical and functional measures, and to compare the pain and disability reported by HAT tear patients to those with end-stage hip osteoarthritis (OA). Study Design Prospective case series. Methods One hundred forty-nine consecutive patients with symptomatic HAT tears were evaluated using the Harris (HHS) and Oxford (OHS) Hip Scores, SF-12, an additional series of 10 questions more pertinent to those with lateral hip pain, active hip range of motion (ROM), maximal isometric hip abduction strength, six-minute walk capacity and 30-second single limb stance (SLS) test. The presence of a Trendelenburg sign and pelvis-on-femur (POF) angle were determined via 2D video analysis. An age matched comparative sample of patients with end-stage hip OA was recruited for comparison of all patient-reported outcome scores. Independent t-tests investigated group and limb differences, while analysis of variance evaluated pain changes during the functional tests. Pearson's correlation coefficients investigated the correlation between clinical measures in the HAT tear group. Results No differences existed in patient demographics and patient-reported outcome scores between HAT tear and hip OA cohorts, apart from significantly worse SF-12 mental subscale scores (p = 0.032) in the HAT tear group. Patients with HAT tears demonstrated significantly lower (p < 0.05) hip abduction strength and active ROM in all planes of motion on their affected limb. Pain significantly increased throughout the 30-second SLS test for the HAT tear group, with 57% of HAT tear patients

  5. The architecture and contraction time of intrinsic foot muscles.

    PubMed

    Tosovic, Danijel; Ghebremedhin, Estifanos; Glen, Christopher; Gorelick, Mark; Mark Brown, J

    2012-12-01

    Although critical for effective human locomotion and posture, little data exists regarding the segmentation, architecture and contraction time of the human intrinsic foot muscles. To address this issue, the Abductor Hallucis (AH), Abductor Digiti Minimi (ADM), Flexor Digitorum Brevis (FDB) and Extensor Digitorum Brevis (EDB) were investigated utilizing a cadaveric dissection and a non-invasive whole muscle mechanomyographic (wMMG) technique. The segmental structure and architecture of formaldehyde-fixed foot specimens were determined in nine cadavers aged 60-80 years. The wMMG technique was used to determine the contraction time (Tc) of individual muscle segments, within each intrinsic foot muscle, in 12 volunteers of both genders aged between 19 and 24 years. While the pattern of segmentation and segmental -architecture (e.g. fibre length) and -Tc of individual muscle segments within the same muscle were similar, they varied between muscles. Also, the average whole muscle Tc of FDB was significantly (p < 0.05) shorter (faster) (Tc = 58 ms) than in all other foot muscles investigated (ADM Tc = 72 ms, EDB Tc = 72 ms and ABH Tc = 69 ms). The results suggest that the architecture and contraction time of the FDB reflect its unique direct contribution, through toe flexion, to postural stability and the rapid development of ground reaction forces during forceful activities such as running and jumping.

  6. High incidence and treatment of flexor carpi radialis tendinitis after trapeziectomy and abductor pollicis longus suspensionplasty for basal joint arthritis.

    PubMed

    Low, T H; Hales, P F

    2014-10-01

    We reviewed the incidence and treatment of flexor carpi radialis tendinitis in 77 patients (81 thumbs) who had trapeziectomy and abductor pollicis longus suspensionplasty for thumb carpometacarpal joint arthritis. Eighteen patients, 20 wrists (25%) had flexor carpi radialis tendinitis. The onset was 2-10 months (mean 4.7) after surgery. Two cases had preceding trauma. Eight cases (40%) responded to splinting and steroid injection. Ten patients, 12 wrists (60%) underwent surgery after failing non-operative treatment. Eleven wrists had frayed or partially torn flexor carpi radialis tendon and one had a complete tendon rupture with pseudotendon formation. Flexor carpi radialis tenotomy and pseudotendon excision were performed. All operated patients obtained good pain relief initially post-operatively. However, the pain recurred in two patients after 8 months. One required a local steroid injection for localized tenderness at the site of the proximal tendon stump. The other patient required a revision operation for scaphotrapezoid impingement. Both obtained complete pain relief. Our study has shown a high incidence of flexor carpi radialis tendinitis following trapeziectomy and abductor pollicis longus suspensionplasty. Patients should be warned about this potential complication.

  7. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum

    PubMed Central

    Loy, Ryan E.; Orynbayev, Murat; Xu, Le; Andronache, Zoita; Apostol, Simona; Zvaritch, Elena; MacLennan, David H.; Meissner, Gerhard; Melzer, Werner

    2011-01-01

    The type 1 isoform of the ryanodine receptor (RYR1) is the Ca2+ release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation–contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1I4898T mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca2+ content, and RYR1 Ca2+ release channel function using adult heterozygous Ryr1I4895T/+ knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca2+ content, both electrically evoked and 4-chloro-m-cresol–induced Ca2+ release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4–6-mo-old IT/+ mice. The sensitivity of the SR Ca2+ release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca2+ permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca2+ release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca2+ ion permeation. PMID:21149547

  8. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum.

    PubMed

    Loy, Ryan E; Orynbayev, Murat; Xu, Le; Andronache, Zoita; Apostol, Simona; Zvaritch, Elena; MacLennan, David H; Meissner, Gerhard; Melzer, Werner; Dirksen, Robert T

    2011-01-01

    The type 1 isoform of the ryanodine receptor (RYR1) is the Ca(2+) release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation-contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1(I4898T) mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca(2+) content, and RYR1 Ca(2+) release channel function using adult heterozygous Ryr1(I4895T/+) knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca(2+) content, both electrically evoked and 4-chloro-m-cresol-induced Ca(2+) release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4-6-mo-old IT/+ mice. The sensitivity of the SR Ca(2+) release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca(2+) permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca(2+) release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca(2+) ion permeation.

  9. Aging changes in the bones - muscles - joints

    MedlinePlus

    Osteoporosis and aging; Muscle weakness associated with aging; Osteoarthritis ... Loss of muscle mass reduces strength. COMMON PROBLEMS Osteoporosis is a common problem, especially for older women. ...

  10. The effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle.

    PubMed

    Jono, Yasutomo; Chujo, Yuta; Nomura, Yoshifumi; Tani, Keisuke; Nikaido, Yasutaka; Hatanaka, Ryota; Hiraoka, Koichi

    2015-01-01

    This study examined the effect of tonic contraction of the finger muscle on the motor cortical representation of the contracting adjacent muscle. A representation map of the motor evoked potential (MEP) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles was obtained with the subject at rest or during tonic contraction of the ADM muscle while the FDI muscle was tonically contracted. The center of gravity (COG) of the MEP map in the FDI muscle shifted medially during contraction of the ADM muscle. Motor cortical excitability in the motor cortical representation of the FDI muscle that did not overlap with the motor cortical representation of the ADM muscle was suppressed, but motor cortical excitability in the motor cortical representation of the FDI muscle overlapping with the motor cortical representation of the ADM muscle was not suppressed during contraction of the ADM muscle. The motor cortical representation of the FDI muscle not overlapping with the motor cortical representation of the ADM muscle was located lateral to that of the FDI muscle that did overlap with the motor cortical representation of the ADM muscle. Medial shift of the COG of the motor cortical representation of the contracting finger muscle induced by tonic contraction of the adjacent finger muscle must be due to suppression of motor cortical excitability in the lateral part of the representation, which is not shared by the adjacent representation.

  11. Isokinetic imbalance of hip muscles in soccer players with osteitis pubis.

    PubMed

    Mohammad, Walaa Sayed; Abdelraouf, Osama Ragaa; Elhafez, Salam Mohamed; Abdel-Aziem, Amr Almaz; Nassif, Nagui Sobhi

    2014-01-01

    In this study, we compared the isokinetic torques of hip flexors/extensors and abductors/adductors in soccer players suffering from osteitis pubis (OP), with normal soccer players. Twenty soccer male athletes with OP and 20 normal soccer athletes were included in this study. Peak torque/body weight (PT/BW) was recorded from hip flexor/extensor and abductor/adductor muscles during isokinetic concentric contraction modes at angular velocity of 2.1 rad · s(-1), for both groups. The results showed a significant difference between the normal and OP groups for hip flexors (P < 0.05). The normal group had significant, lower PT/BW value than the OP group for their hip flexors (P < 0.05). The hip flexor/extensor PT ratio of OP affected and non-affected limbs was significantly different from that of normal dominant and non-dominant limbs. There were no significant differences between the normal and OP groups for hip extensor, adductor and abductor muscles (P > 0.05). Regarding the hip adductor/abductor PT ratio, there was no significant difference between the normal and OP groups of athletes (P > 0.05). The OP group displayed increase in hip flexor strength that disturbed the hip flexor/extensor torque ratio of OP. Therefore, increasing the hip extensor strength should be part of rehabilitation programmes of patients with OP.

  12. Anticipatory and Reactive Response to Falls: Muscle Synergy Activation of Forearm Muscles.

    PubMed

    Couzens, Greg; Kerr, Graham

    2015-10-01

    We investigated the surface electromyogram response of six forearm muscles to falls onto the outstretched hand. The extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, abductor pollicis longus, flexor carpi radialis and flexor carpi ulnaris muscles were sampled from eight volunteers who underwent ten self-initiated falls. All muscles initiated prior to impact. Co-contraction is the most obvious surface electromyogram feature. The predominant response is in the radial deviators. The surface electromyogram timing we recorded would appear to be a complex anticipatory response to falling modified by the effect on the forearm muscles following impact. The mitigation of the force of impact is probably more importantly through shoulder abduction and extension and elbow flexion rather than action of the forearm muscles.

  13. Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1957-06-01

    Experimental results on the non-conservation of parity and charge conservation in weak interactions are reviewed. The two-component theory of the neutrino is discussed. Lepton reactions are examined under the assumption of the law of conservation of leptons and that the neutrino is described by a two- component theory. From the results of this examination, the universal Fermi interactions are analyzed. Although reactions involving the neutrino can be described, the same is not true of reactions which do not involve the lepton, as the discussion of the decay of K mesons and hyperons shows. The question of the invariance of time reversal is next examined. (J.S.R.)

  14. Variations in abductor pollicis longus and extensor pollicis brevis tendons in the Quervain syndrome: a surgical and anatomical study.

    PubMed

    Kulthanan, Teerawat; Chareonwat, Boonsong

    2007-01-01

    Eighty-two wrists of Thai cadavers and the wrists of 66 patients with de Quervain syndrome were studied, and the variation in the number of tendons and the fibro-osseous tunnel in the first extensor compartment were recorded. The abductor pollicis longus had more than one tendon in 73 of the cadavers (89%) and in 32 of the patients (49%) (p <0.001). The extensor pollicis brevis was a single tendon in 80 (98%) and 62 (94%) of cadavers and patients, respectively. There was division with the septum that made a fibro-osseous tunnel in the first extensor compartment in 30/82 (37%) cadavers and in 38/66 (58%) patients with de Quervain syndrome (p = 0.01). The results indicate that the number of fibro-osseous tunnels and multiple compartments in the first extensor compartment may be associated with a predisposition to de Quervain syndrome.

  15. [Obese woman presenting as vocal cord abductor paralysis and floppy arytenoid associated with early signs of multiple system atrophy].

    PubMed

    Sakuta, Hideki; Miyamoto, Masayuki; Suzuki, Keisuke; Miyamoto, Tomoyuki; Nakajima, Itsuo; Nakamura, Toshiki; Hirata, Koichi

    2012-01-01

    In multiple system atrophy (MSA), sleep-related breathing disorders are commonly observed, including vocal cord abductor paralysis (VCAP), which can cause sudden death. In its early stage, VCAP occurs only during sleep, but as the disease progresses, it appears when both awake and asleep. We encountered a 59-year-old obese woman who had been under continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea syndrome (OSAS) for approximately one year but later developed acute respiratory failure because of VCAP. VCAP was the predominant finding that led to the diagnosis of MSA in our patient. On laryngoscopic examination, the movement of the patient's larynx was normal during wakefulness, but VCAP, paradoxical movements of the vocal cord and a floppy arytenoid were observed during drug-induced sleep. We suggest that detection of VCAP and laryngopharyngeal abnormalities such as floppy arytenoid in the early stage of MSA is important for determining treatment options.

  16. Weakness of the Pelvic Floor Muscle and Bladder Neck Is Predicted by a Slight Rise in Abdominal Pressure During Bladder Filling: A Video Urodynamic Study in Children

    PubMed Central

    2016-01-01

    Purpose: To investigate the significance of slowly rising abdominal pressure (SRAP), which is often observed in nonneurogenic children during bladder filling in video urodynamic studies (VUDSs). Methods: The records of patients who underwent VUDS from July 2011 to June 2013 were reviewed. SRAP was defined as a rising curve over 5 cm H2O from the baseline abdominal pressure during the filling phase in VUDS. Bladder descent was defined when the base of the bladder was below the upper line of the pubic symphysis. An open bladder neck was defined as the opening of the bladder neck during the filling phase. Results: Of the 488 patients, 285 were male patients. The mean age at VUDS was 3.7 years (range, 0.2–17.6 years). The VUDS findings were as follows: SRAP, 20.7% (101 of 488); descending bladder, 14.8% (72 of 488); and bladder neck opening, 4.3% (21 of 488). Of the 72 patients with a descending bladder, 84.7% had SRAP. A significant difference in the presence of SRAP was found between the descending bladder and the normal bladder (P<0.001). Of the 101 patients with SRAP, 40 (39.6%) did not have a descending bladder. Of the 40 patients, 14 (35.0%) had a bladder neck opening, which was a high incidence compared with the 4.3% in all subjects (P<0.001). Conclusions: SRAP was associated with a descending bladder or a bladder neck opening, suggesting that SRAP is a compensatory response to urinary incontinence. SRAP may also predict decreased function of the bladder neck or pelvic floor muscle. PMID:27032558

  17. Motor unit estimation in a muscle supplied by the radial nerve.

    PubMed Central

    Defaria, C R; Toyonaga, K

    1978-01-01

    The number of motor units in a muscle, the abductor pollicis longus (APL), supplied by the radial nerve was estimated. In 40 APL muscles of control subjects, the mean number of motor units was found to be 421 +/- 99 (SD). Ten patients underwent conventional EMG examination to confirm the clinical suspicion of denervation in radial nerve territory. All presented a significant reduction in the number of motor units in the APL muscle. These results show that this method is useful in the evaluation of muscles supplied by the radial nerve. PMID:690650

  18. Normal insulin release during sustained hyperglycaemia in hypokalaemic periodic paralysis: role of the potassium channel opener pinacidil in impaired muscle strength.

    PubMed

    Ligtenberg, J J; Van Haeften, T W; Van Der Kolk, L E; Smit, A J; Sluiter, W J; Reitsma, W D; Links, T P

    1996-11-01

    1. Hypokalaemic periodic paralysis is characterized by attacks of muscle weakness. Glucose, insulin and an abnormal regulation of ATP-sensitive potassium channels may be involved in these attacks. We studied the effect of hyperglycaemia and of the potassium channel opener pinacidil on insulin release and muscle strength in patients with hypokalaemic periodic paralysis. 2. Insulin release was assessed on two occasions in four patients with hypokalaemic periodic paralysis and in eight matched control subjects, with and without treatment with 25 mg pinacidil orally, during a hyperglycaemic glucose clamp at a blood glucose level of 10 mmol/l, in a placebo-controlled, double-blind study. Muscle strength was measured in the hypokalaemic periodic paralysis patients before and during hyperglycaemia using a handheld dynamometer. 3. During the clamp, the mean glucose concentration (10-180 min) in control subjects was 9.9 +/- 0.07 and 10.0 +/- 0.03 mmol/l with and without pinacidil respectively, and in patients with hypokalaemic periodic paralysis was 10.0 +/- 0.04 and 10.1 +/- 0.06 mmol/l respectively (not significantly different). In both groups, the areas under the insulin curve from 0 to 10 min (first-phase insulin release) and from 30 to 180 min (second phase) were not different on the pinacidil study day compared with on the placebo day. The areas under the insulin curve of the first and second phases also did not differ between control subjects and patients with hypokalaemic periodic paralysis (with or without pinacidil). The M/I ratio, a measure of insulin sensitivity, was not different in the two groups. On the placebo day, baseline muscle strength in patients with hypokalaemic periodic paralysis was 165 +/- 16 N for the hip abductors and 168 +/- 19 N for the knee flexors. During the period of hyperglycaemia on the placebo day, muscle strength did not decrease in either muscle group. On the pinacidil study day, an increase in muscle strength was found only in the two

  19. Examination of Hand Muscle Activation and Motor Unit Indices Derived from Surface EMG in Chronic Stroke

    PubMed Central

    Li, Xiaoyan; Liu, Jie; Li, Sheng; Wang, Ying-Chih

    2014-01-01

    In this study, we used muscle and motor unit indices, derived from convenient surface electromyography (EMG) measurements, for examination of paretic muscle changes post stroke. For 12 stroke subjects, compound muscle action potential and voluntary surface EMG signals were recorded from paretic and contralateral first dorsal interosseous, abductor pollicis brevis, and abductor digiti minimi muscles. Muscle activation index (AI), motor unit number index (MUNIX), and motor unit size index (MUSIX) were then calculated for each muscle. There was a significant AI reduction for all the three muscles in paretic side compared with contralateral side, providing an evidence of muscle activation deficiency after stroke. The hand MUNIX (defined by summing the values from the three muscles) was significantly reduced in paretic side compared with contralateral side, whereas the hand MUSIX was not significantly different. Furthermore, diverse changes in MUNIX and MUSIX were observed from the three muscles. A major feature of the present examinations is the primary reliance on surface EMG, which offers practical benefits because it is noninvasive, induces minimal discomfort and can be performed quickly. PMID:24967982

  20. A muscle spindle abnormity in one laryngeal muscle would be sufficient to cause stuttering.

    PubMed

    Schuster, Steffen H; Schuster, Frank M

    2012-07-01

    Muscle spindles are increasingly recognized as playing a pivotal role in the cause of dystonia. This development and own laryngeal observations that support the idea of causally "well-intentioned" stuttering motivated us to present the following hypothesis: stuttering events compensate for a sensory problem that arises when the abductor/adductor ratio of afferent impulse rates from the posterior cricoarytenoid and lateral cricoarytenoid muscle spindles is abnormally reduced and processed for the occasional determination of the vocal fold position. This hypothesis implies that functional and structural brain abnormalities might be interpreted as secondary compensatory reactions. Verification of this hypothesis (using technologies such as microneurography, dissection and muscle afferent block) is important because its confirmation could relink dystonia and stuttering research, change the direction of stuttering therapy and destigmatize stuttering radically.

  1. Muscle fiber types composition and type identified endplate morphology of forepaw intrinsic muscles in the rat.

    PubMed

    Pan, Feng; Mi, Jing-Yi; Zhang, Yan; Pan, Xiao-Yun; Rui, Yong-Jun

    2016-06-01

    The failure to accept reinnervation is considered to be one of the reasons for the poor motor functional recovery of intrinsic hand muscles (IHMs) after nerve injury. Rat could be a suitable model to be used in simulating motor function recovery of the IHMs after nerve injury as to the similarities in function and anatomy of the muscles between human and rat. However, few studies have reported the muscle fiber types composition and endplate morphologic characteristics of intrinsic forepaw muscles (IFMs) in the rat. In this study, the myosin heavy chain isoforms and acetylcholine receptors were stained by immunofluorescence to show the muscle fiber types composition and endplates on type-identified fibers of the lumbrical muscles (LMs), interosseus muscles (IMs), abductor digiti minimi (AM) and flexor pollicis brevis (FM) in rat forepaw. The majority of IFMs fibers were labeled positively for fast-switch fiber. However, the IMs were composed of only slow-switch fiber. With the exception of the IMs, the other IFMs had a part of hybrid fibers. Two-dimensional morphological characteristics of endplates on I and IIa muscle fiber had no significant differences among the IFMs. The LMs is the most suitable IFMs of rat to stimulate reinnervation of the IHMs after nerve injury. Gaining greater insight into the muscle fiber types composition and endplate morphology in the IFMs of rat may help understand the pathological and functional changes of IFMs in rat model stimulating reinnervation of IHMs after peripheral nerve injury.

  2. Effects of augmented trunk stabilization with external compression support on shoulder and scapular muscle activity and maximum strength during isometric shoulder abduction.

    PubMed

    Jang, Hyun-jeong; Kim, Suhn-yeop; Oh, Duck-won

    2015-04-01

    The aim of the present study was to investigate the effects of augmented trunk stabilization with external compression support (ECS) on the electromyography (EMG) activity of shoulder and scapular muscles and shoulder abductor strength during isometric shoulder abduction. Twenty-six women volunteered for the study. Surface EMG was used to monitor the activity of the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and middle deltoid (MD), and shoulder abductor strength was measured using a dynamometer during three experimental conditions: (1) no external support (condition-1), (2) pelvic support (condition-2), and (3) pelvic and thoracic supports (condition-3) in an active therapeutic movement device. EMG activities were significantly lower for UT and higher for MD during condition 3 than during condition 1 (p < 0.05). The MD/UT ratio was significantly higher during condition 3 than during conditions 1 and 2, and higher during condition 2 than during condition 1 (p < 0.05). Shoulder abductor strength was significantly higher during condition 3 than during condition 1 (p < 0.05). These findings suggest that augmented trunk stabilization with the ECS may be advantageous with regard to reducing the compensatory muscle effort of the UT during isometric shoulder abduction and increasing shoulder abductor strength.

  3. The contribution of the palmaris longus muscle to the strength of thumb abduction.

    PubMed

    Gangata, Hope; Ndou, Robert; Louw, Graham

    2010-05-01

    The palmaris longus muscle (PLM) is described as a weak flexor of the wrist and a tensor of the palmar aponeurosis, but not a thumb abductor. The PLM is believed to aid thumb abduction through its insertion onto the thenar eminence. Two groups, both right hand dominant, were selected from 1,200 sampled participants. The first group comprised of 38 subjects with unilateral presence of the PLM and was used to determine the strength of thumb abduction. The second group comprised of 30 subjects, with bilateral presence of the PLM, and it was used to calculate the effects of hand dominance. A significant number of subjects with bilateral absence of the PLM were observed and undocumented. Using a dynamometer in subjects with unilateral presence of the PLM, the force of thumb abduction was significantly greater on the hand with a PLM than the one without it (P = 0.014), irrespective of hand dominance. In the second sample with bilateral PLM, thumb abduction on the dominant hand was 10% stronger than on the nondominant hand and was similar to the universally accepted average of 10% increase in grip strength of the dominant hand. Thus, 10% was deducted from all the dominant hands, and the force of thumb abduction remained greater on the hand with PLM than the hand without it (P = 0.049). The results of this study demonstrated the PLM to be involved in thumb abduction, and the authors therefore recommend that this action of the muscle be universally accepted by anatomists and hand surgeons.

  4. A heroin addict with focal weakness.

    PubMed

    Galassi, Giuliana; Ariatti, Alessandra; Gozzi, Manuela; Cavazza, Stefano

    2013-05-01

    A 24-year-old female with 5 year history of heroin abuse experienced painless stiffness of elbow joints and weakness of shoulder and upper limb muscles. She was injecting herself 4-6 times daily alternatively in the upper extremities, sparing the lower limbs. Electromyography (EMG) showed myopathic changes in clinically affected and unaffected muscles. Magnetic resonance imaging (MRI) revealed muscle fibrosis in directly injected muscles, whereas in subcutaneous fat and within muscles of anterior and posterior compartments of both thighs, not directly injected, there were signal changes supportive of oedema and inflammation. EMG and MRI were congruent in showing abnormalities in muscles not directly injected, suggesting long distant effects of heroin or adulterants with a mechanism either toxic or immunologically mediated.

  5. Effect of muscle contraction strength on gating of somatosensory magnetic fields.

    PubMed

    Sugawara, Kazuhiro; Onishi, Hideaki; Yamashiro, Koya; Kotan, Shinichi; Kojima, Sho; Miyaguchi, Shota; Tsubaki, Atsuhiro; Kirimoto, Hikari; Tamaki, Hiroyuki; Shirozu, Hiroshi; Kameyama, Shigeki

    2016-11-01

    Afferent somatosensory information is modulated before the afferent input arrives at the primary somatosensory cortex during voluntary movement. The aim of the present study was to clarify the effect of muscular contraction strength on somatosensory evoked fields (SEFs) during voluntary movement. In addition, we examined the differences in gating between innervated and non-innervated muscle during contraction. We investigated the changes in gating effect by muscular contraction strength and innervated and non-innervated muscles in human using 306-channel magnetoencephalography. SEFs were recorded following the right median nerve stimulation in a resting condition and during isometric muscular contractions from 10 % electromyographic activity (EMG), 20 and 30 % EMG of the right extensor indicis muscle and abductor pollicis brevis muscle. Our results showed that the equivalent current dipole (ECD) strength for P35m decreased with increasing strength of muscular contraction of the right abductor pollicis brevis muscle. However, changes were observed only at 30 % EMG contraction level of the right extensor indicis muscle, which was not innervated by the median nerve. There were no significant changes in the peak latencies and ECD locations of each component in all conditions. The ECD strength did not differ significantly for N20m and P60m regardless of the strength of muscular contraction and innervation. Therefore, we suggest that the gating of SEF waveforms following peripheral nerve stimulation was affected by the strength of muscular contraction and innervation of the contracting muscle.

  6. The effects of hip external rotator exercises and toe-spread exercises on lower extremity muscle activities during stair-walking in subjects with pronated foot

    PubMed Central

    Goo, Young-Mi; Kim, Da-Yeon; Kim, Tae-Ho

    2016-01-01

    [Purpose] The purpose of the present study was to examine the effects of toe-spread (TS) exercises and hip external rotator strengthening exercises for pronated feet on lower extremity muscle activities during stair-walking. [Subjects and Methods] The participants were 20 healthy adults with no present or previous pain, no past history of surgery on the foot or the ankle, and no foot deformities. Ten subjects performed hip external rotator strengthening exercises and TS exercises and the remaining ten subjects performed only TS exercises five times per week for four weeks. [Results] Less change in navicular drop height occurred in the group that performed hip external rotator exercises than in the group that performed only TS exercises. The group that performed only TS exercises showed increased abductor hallucis muscle activity during both stair-climbing and -descending, and the group that performed hip external rotator exercises showed increased muscle activities of the vastus medialis and abductor hallucis during stair-climbing and increased muscle activity of only the abductor hallucis during stair-descending after exercise. [Conclusion] Stair-walking can be more effectively performed if the hip external rotator muscle is strengthened when TS exercises are performed for the pronated foot. PMID:27134364

  7. Electrically and Hybrid-Induced Muscle Activations: Effects of Muscle Size and Fiber Type

    PubMed Central

    Stratton, Kelly; Faghri, Pouran D.

    2016-01-01

    The effect of three electrical stimulation (ES) frequencies (10, 35, and 50 Hz) on two muscle groups with different proportions of fast and slow twitch fibers (abductor pollicis brevis (APB) and vastus lateralis (VL)) was explored. We evaluated the acute muscles’ responses individually and during hybrid activations (ES superimposed by voluntary activations). Surface electromyography (sEMG) and force measurements were evaluated as outcomes. Ten healthy adults (mean age: 24.4 ± 2.5 years) participated after signing an informed consent form approved by the university Institutional Review Board. Protocols were developed to: 1) compare EMG activities during each frequency for each muscle when generating 25% Maximum Voluntary Contraction (MVC) force, and 2) compare EMG activities during each frequency when additional voluntary activation was superimposed over ES-induced 25% MVC to reach 50% and 75% MVC. Empirical mode decomposition (EMD) was utilized to separate ES artifacts from voluntary muscle activation. For both muscles, higher stimulation frequency (35 and 50Hz) induced higher electrical output detected at 25% of MVC, suggesting more recruitment with higher frequencies. Hybrid activation generated proportionally less electrical activity than ES alone. ES and voluntary activations appear to generate two different modes of muscle recruitment. ES may provoke muscle strength by activating more fatiguing fast acting fibers, but voluntary activation elicits more muscle coordination. Therefore, during the hybrid activation, less electrical activity may be detected due to recruitment of more fatigue-resistant deeper muscle fibers, not reachable by surface EMG. PMID:27990244

  8. Your Muscles

    MedlinePlus

    ... Room? What Happens in the Operating Room? Your Muscles KidsHealth > For Kids > Your Muscles A A A ... and skeletal (say: SKEL-uh-tul) muscle. Smooth Muscles Smooth muscles — sometimes also called involuntary muscles — are ...

  9. [A strong man with a weak shoulder].

    PubMed

    Henket, Marjolijn; Lycklama á Nijeholt, Geert J; van der Zwaal, Peer

    2013-01-01

    A 47-year-old former olympic athlete had pain and weakness of his left shoulder. There was no prior trauma. He had full range-of-motion and a scapular dyskinesia. There was atrophy of the trapezius and sternocleidomastoideus muscles. He was diagnosed with 'idiopathic neuritis of the accessorius nerve'.

  10. Reliability of ultrasound to measure morphology of the toe flexor muscles

    PubMed Central

    2013-01-01

    Background Measuring the strength of individual foot muscles is very challenging; however, measuring muscle morphology has been shown to be associated with strength. A reliable method of assessing foot muscle atrophy and hypertrophy would therefore be beneficial to researchers and clinicians. Thus, the aim of this study was to evaluate the test-retest intra-observer reliability of ultrasound to measure the morphology of the primary toe flexor muscles. Method The abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae and abductor digiti minimi muscles in the foot, and the flexor digitorum longus and flexor hallucis longus muscles in the shank were assessed in five males and five females (mean age = 32.1 ± 10.1 years). Muscles were imaged using a GE Venue 40 ultrasound (6-9 or 7.6-10.7 MHz transducer) in a random order, and on two occasions 1-6 days apart. Muscle thickness and cross-sectional area were measured using Image J software with the assessor blinded to muscle and day of scan. Intraclass correlation coefficients (ICC) and limits of agreement were calculated to assess day-to-day repeatability of the measurements. Results The method was found to have good reliability (ICC = 0.89-0.99) with limits of agreement between 8-28% of the relative muscle size. Conclusion The protocol described in this paper showed that ultrasound is a reliable method to measure morphology of the toe flexor muscles. The portability and advantages of ultrasound make it a useful tool for clinical and research settings. PMID:23557252

  11. Comments and corrections on 3D modeling studies of locomotor muscle moment arms in archosaurs

    PubMed Central

    Maidment, Susannah C.R.; Schachner, Emma R.; Barrett, Paul M.

    2015-01-01

    In a number of recent studies we used computer modeling to investigate the evolution of muscle leverage (moment arms) and function in extant and extinct archosaur lineages (crocodilians, dinosaurs including birds and pterosaurs). These studies sought to quantify the level of disparity and convergence in muscle moment arms during the evolution of bipedal and quadrupedal posture in various independent archosaur lineages, and in doing so further our understanding of changes in anatomy, locomotion and ecology during the group’s >250 million year evolutionary history. Subsequent work by others has led us to re-evaluate our models, which revealed a methodological error that impacted on the results obtained from the abduction–adduction and long-axis rotation moment arms in our published studies. In this paper we present corrected abduction–adduction and long axis rotation moment arms for all our models, and evaluate the impact of this new data on the conclusions of our previous studies. We find that, in general, our newly corrected data differed only slightly from that previously published, with very few qualitative changes in muscle moments (e.g., muscles originally identified as abductors remained abductors). As a result the majority of our previous conclusions regarding the functional evolution of key muscles in these archosaur groups are upheld. PMID:26500810

  12. Inter-tester reliability and precision of manual muscle testing and hand-held dynamometry in lower limb muscles of children with spina bifida.

    PubMed

    Mahony, Kate; Hunt, Adrienne; Daley, Deborah; Sims, Susan; Adams, Roger

    2009-01-01

    Reliability and measurement precision of manual muscle testing (MMT) and hand-held dynamometry (HHD) were compared for children with spina bifida. Strength measures were obtained of the hip flexors, hip abductors, and knee extensors of 20 children (10 males, 10 females; mean age 9 years 10 months; range: 5 to 15 years) by two experienced physical therapists and a student physical therapist. Inter-tester reliability [ICC(2,1)] for HHD varied from 0.76 to 0.83, indicating excellent reliability for the three muscle groups. Inter-tester reliability for MMT was 0.75 for the hip abductor muscle group, indicating good reliability, and 0.37 to 0.40 for the remaining muscle groups. The minimum detectable change was 15N for HHD and 1 scale unit of a 0 to 5 MMT scale. The results suggest a situation-specific solution to the question of which method to use. To detect small strength changes over time in children with spina bifida, MMT should be used when the child has insufficient strength to move the limb against gravity; otherwise, HHD should be used.

  13. Characteristics of the electrophysiological activity of muscles attached to the transverse carpal ligament in carpal tunnel syndrome.

    PubMed

    Horiguchi, Gen; Aoki, Takafumi; Ito, Hiromoto

    2011-01-01

    The main cause of carpal tunnel syndrome (CTS) remains unknown. Stiffness of the subcutaneous area of the volar aspect of the carpal tunnel is present in many patients and suggests that the stiffness of muscles attached to the transverse carpal ligament is increased. We performed an electrophysiological study to investigate muscle activities and to clarify whether the stiffness of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS. The subjects of this study included 16 patients with early CTS showing no motor dysfunction. Both thenar muscles (opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis) and hypothenar muscles (opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis) were investigated. Surface electrodes were placed on each muscle, and maximum voluntary contractions with the thumb and little finger in opposition were maintained for 3 seconds in all patients and in 7 control subjects. Electromyographs were subjected to fast Fourier transform analysis, and the root mean square (RMS) and the mean power frequency (MPF) were determined for each muscle. The RMS of the opponens pollicis was significantly less in hands affected by CTS (292.8 µV) than in healthy hands (405.9 µV). The RMS did not differ between affected hands and healthy hands for the other 2 thenar muscles but did differ significantly for the hypothenar muscles. The MPF did not differ between affected hands and healthy hands for any muscle. The results show that electrophysiological differences are present among muscles innervated by the median nerve and that hypothenar muscles originally unrelated to median nerve dysfunction are also affected in early CTS. These results suggest that modulation of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS.

  14. Postselected weak measurement beyond the weak value

    SciTech Connect

    Geszti, Tamas

    2010-04-15

    Closed expressions are derived for the quantum measurement statistics of pre- and postselected Gaussian particle beams. The weakness of the preselection step is shown to compete with the nonorthogonality of postselection in a transparent way. The approach is shown to be useful in analyzing postselection-based signal amplification, allowing measurements to be extended far beyond the range of validity of the well-known Aharonov-Albert-Vaidman limit. Additionally, the present treatment connects postselected weak measurement to the topic of phase-contrast microscopy.

  15. Patterns of muscle activity for digital coarticulation

    PubMed Central

    Winges, Sara A.; Furuya, Shinichi; Faber, Nathaniel J.

    2013-01-01

    Although piano playing is a highly skilled task, basic features of motor pattern generation may be shared across tasks involving fine movements, such as handling coins, fingering food, or using a touch screen. The scripted and sequential nature of piano playing offered the opportunity to quantify the neuromuscular basis of coarticulation, i.e., the manner in which the muscle activation for one sequential element is altered to facilitate production of the preceding and subsequent elements. Ten pianists were asked to play selected pieces with the right hand at a uniform tempo. Key-press times were recorded along with the electromyographic (EMG) activity from seven channels: thumb flexor and abductor muscles, a flexor for each finger, and the four-finger extensor muscle. For the thumb and index finger, principal components of EMG waveforms revealed highly consistent variations in the shape of the flexor bursts, depending on the type of sequence in which a particular central key press was embedded. For all digits, the duration of the central EMG burst scaled, along with slight variations across subjects in the duration of the interkeystroke intervals. Even within a narrow time frame (about 100 ms) centered on the central EMG burst, the exact balance of EMG amplitudes across multiple muscles depended on the nature of the preceding and subsequent key presses. This fails to support the idea of fixed burst patterns executed in sequential phases and instead provides evidence for neuromuscular coarticulation throughout the time course of a hand movement sequence. PMID:23596338

  16. Force steadiness, muscle activity, and maximal muscle strength in subjects with subacromial impingement syndrome.

    PubMed

    Bandholm, Thomas; Rasmussen, Lars; Aagaard, Per; Jensen, Bente Rona; Diederichsen, Louise

    2006-11-01

    We investigated the effects of the subacromial impingement syndrome (SIS) on shoulder sensory-motor control and maximal shoulder muscle strength. It was hypothesized that both would be impaired due to chronic shoulder pain associated with the syndrome. Nine subjects with unilateral SIS who remained physically active in spite of shoulder pain and nine healthy matched controls were examined to determine isometric and isokinetic submaximal shoulder-abduction force steadiness at target forces corresponding to 20%, 27.5%, and 35% of the maximal shoulder abductor torque, and maximal shoulder muscle strength (MVC). Electromyographic (EMG) activity was assessed using surface and intramuscular recordings from eight shoulder muscles. Force steadiness was impaired in SIS subjects during concentric contractions at the highest target force level only, with muscle activity largely unaffected. No between-group differences in shoulder MVC were observed. The present data suggest that shoulder sensory-motor control is only mildly impaired in subjects with SIS who are able to continue with upper body physical activity in spite of shoulder pain. Thus, physical activity should be continued by patients with SIS, if possible, to avoid the loss in neural and muscle functions associated with inactivity.

  17. Muscle Cramps

    MedlinePlus

    Muscle cramps are sudden, involuntary contractions or spasms in one or more of your muscles. They often occur after exercise or at night, ... to several minutes. It is a very common muscle problem. Muscle cramps can be caused by nerves ...

  18. Your Muscles

    MedlinePlus

    ... of the heart because it controls the heartbeat. Skeletal Muscle Now, let's talk about the kind of muscle ... soccer ball into the goal. These are your skeletal muscles — sometimes called striated (say: STRY-ay-tud) muscle ...

  19. Arthroscopic gluteal muscle contracture release with radiofrequency energy.

    PubMed

    Liu, Yu-Jie; Wang, Yan; Xue, Jing; Lui, Pauline Po-Yee; Chan, Kai-Ming

    2009-03-01

    Gluteal muscle contracture is common after repeated intramuscular injections and sometimes is sufficiently debilitating to require open surgery. We asked whether arthroscopic release of gluteal muscle contracture using radiofrequency energy would decrease complications with clinically acceptable results. We retrospectively reviewed 108 patients with bilateral gluteal muscle contractures (57 males, 51 females; mean age, 23.7 years). We used inferior, anterosuperior, and posterosuperior portals. With the patient lying laterally, we developed and enlarged a potential space between the gluteal muscle group and the subcutaneous fat using blunt dissection. Under arthroscopic guidance through the inferior portal, we débrided and removed fatty tissue overlying the contractile band of the gluteal muscle group using a motorized shaver introduced through the superior portal. Radiofrequency then was introduced through the superior portal to gradually excise the contracted bands from superior to inferior. Finally, hemostasis was ensured using radiofrequency. Patients were followed a minimum of 7 months (mean, 17.4 months; range, 7-42 months). At last followup, the adduction and flexion ranges of the hip were 45.3 degrees +/- 8.7 degrees and 110.2 degrees +/- 11.9 degrees, compared with 10.4 degrees +/- 7.2 degrees and 44.8 degrees +/- 14.1 degrees before surgery. No hip abductor contracture recurred and no patient had residual hip pain or gluteal muscle wasting. We found gluteal muscle contracture could be released effectively with radiofrequency energy.

  20. Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

    PubMed

    Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

    2015-08-01

    Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (<60% of Maximal Voluntary Contraction, MVC). This measurement can therefore be used to estimate changes in individual muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus.

  1. Robust Weak Measurements

    NASA Astrophysics Data System (ADS)

    Tollaksen, Jeff; Aharonov, Yakir

    2006-03-01

    We introduce a new type of weak measurement which yields a quantum average of weak values that is robust, outside the range of eigenvalues, extends the valid regime for weak measurements, and for which the probability of obtaining the pre- and post-selected ensemble is not exponentially rare. This result extends the applicability of weak values, shifts the statistical interpretation previously attributed to weak values and suggests that the weak value is a property of every pre- and post-selected ensemble. We then apply this new weak measurement to Hardy's paradox. Usually the paradox is dismissed on grounds of counterfactuality, i.e., because the paradoxical effects appear only when one considers results of experiments which do not actually take place. We suggest a new set of measurements in connection with Hardy's scheme, and show that when they are actually performed, they yield strange and surprising outcomes. More generally, we claim that counterfactual paradoxes point to a deeper structure inherent to quantum mechanics characterized by weak values (Aharonov Y, Botero A, Popescu S, Reznik B, Tollaksen J, Physics Letters A, 301 (3-4): 130-138, 2002).

  2. Relationships of ultrasound measures of intrinsic foot muscle cross-sectional area and muscle volume with maximum toe flexor muscle strength and physical performance in young adults

    PubMed Central

    Abe, Takashi; Tayashiki, Kota; Nakatani, Miyuki; Watanabe, Hironori

    2016-01-01

    [Purpose] To investigate the relationships between toe flexor muscle strength with (TFS-5-toes) and without (TFS-4-toes) the contribution of the great toe, anatomical and physiological muscle cross-sectional areas (CSA) of intrinsic toe flexor muscle and physical performance were measured. [Subjects] Seventeen men (82% sports-active) and 17 women (47% sports-active), aged 20 to 35 years, volunteered. [Methods] Anatomical CSA was measured in two intrinsic toe flexor muscles (flexor digitorum brevis [FDB] and abductor hallucis) by ultrasound. Muscle volume and muscle length of the FDB were also estimated, and physiological CSA was calculated. [Results] Both TFS-5-toes and TFS-4-toes correlated positively with walking speed in men (r=0.584 and r=0.553, respectively) and women (r=0.748 and r=0.533, respectively). Physiological CSA of the FDB was significantly correlated with TFS-5-toes (r=0.748) and TFS-4-toes (r=0.573) in women. In men, physiological CSA of the FDB correlated positively with TFS-4-toes (r=0.536), but not with TFS-5-toes (r=0.333). [Conclusion] Our results indicate that physiological CSA of the FDB is moderately associated with TFS-4-toes while toe flexor strength correlates with walking performance. PMID:26957721

  3. Intensive care unit-acquired weakness.

    PubMed

    Horn, J; Hermans, G

    2017-01-01

    When critically ill, a severe weakness of the limbs and respiratory muscles often develops with a prolonged stay in the intensive care unit (ICU), a condition vaguely termed intensive care unit-acquired weakness (ICUAW). Many of these patients have serious nerve and muscle injury. This syndrome is most often seen in surviving critically ill patients with sepsis or extensive inflammatory response which results in increased duration of mechanical ventilation and hospital length of stay. Patients with ICUAW often do not fully recover and the disability will seriously impact on their quality of life. In this chapter we discuss the current knowledge on the pathophysiology and risk factors of ICUAW. Tools to diagnose ICUAW, how to separate ICUAW from other disorders, and which possible treatment strategies can be employed are also described. ICUAW is finally receiving the attention it deserves and the expectation is that it can be better understood and prevented.

  4. History of Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1970-07-01

    While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

  5. Distribution of electrophysiological abnormality in Lambert-Eaton myasthenic syndrome

    PubMed Central

    Maddison, P.; Newsom-Davis, J.; Mills, K.

    1998-01-01

    OBJECTIVE—To assess the distribution of electrophysiological abnormality in Lambert-Eaton myasthenic syndrome (LEMS) to identify the most sensitive muscle to use in routine examination.
METHODS—Surface recorded compound muscle action potential (CMAP) amplitudes were made from abductor digiti minimi, abductor pollicis brevis, anconeus, biceps brachii, and trapezius in 10 patients with LEMS. The effect of 3,4-diaminopyridine (3,4-DAP) was recorded in each muscle in nine patients. CMAP amplitudes were measured at rest and immediately after 10 seconds maximal voluntary contraction in each muscle. Values were compared with results obtained from 12 healthy controls.
RESULTS—Resting CMAP amplitudes were reduced in at least one muscle in all patients compared with controls, most markedly in abductor digiti minimi and anconeus. The administration of 3,4-DAP resulted in significantly improved resting CMAP amplitudes in trapezius only. After maximal voluntary muscle contraction, characteristic increments in CMAP amplitude of over 100% above resting values were seen in abductor digiti minimi and abductor pollicis brevis in seven patients, anconeus and biceps brachii in five patients. No patient had this level of increment in trapezius.
CONCLUSION—Despite predominantly proximal limb weakness seen clinically in patients with LEMS, the most sensitive muscles for detecting characteristic electrophysiological abnormalities of low resting CMAP amplitude and increment of over 100% after 10 seconds maximal voluntary contraction are abductor digiti minimi, abductor pollicis brevis, and anconeus.

 PMID:9703174

  6. Skeletal muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are approximately 650-850 muscles in the human body these include skeletal (striated), smooth and cardiac muscle. The approximation is based on what some anatomists consider separate muscle or muscle systems. Muscles are classified based on their anatomy (striated vs. smooth) and if they are v...

  7. Cerebellar brain inhibition in the target and surround muscles during voluntary tonic activation.

    PubMed

    Panyakaew, Pattamon; Cho, Hyun Joo; Srivanitchapoom, Prachaya; Popa, Traian; Wu, Tianxia; Hallett, Mark

    2016-04-01

    Motor surround inhibition is the neural mechanism that selectively favours the contraction of target muscles and inhibits nearby muscles to prevent unwanted movements. This inhibition was previously reported at the onset of a movement, but not during a tonic contraction. Cerebellar brain inhibition (CBI) is reduced in active muscles during tonic activation; however, it has not been studied in the surround muscles. CBI was evaluated in the first dorsal interosseus (FDI) muscle as the target muscle, and the abductor digiti minimi, flexor carpi radialis and extensor carpi radialis muscles as surround muscles, during rest and tonic activation of the FDI muscle in 21 subjects. Cerebellar stimulation was performed under magnetic resonance imaging-guided neuronavigation targeting lobule VIII of the cerebellar hemisphere. Stimulus intensities for cerebellar stimulation were based on the resting motor cortex threshold (RMT) and adjusted for the depth difference between the cerebellar and motor cortices. We used 90-120% of the adjusted RMT as the conditioning stimulus intensity during rest. The intensity that generated the best CBI at rest in the FDI muscle was selected for use during tonic activation. During selective tonic activation of the FDI muscle, CBI was significantly reduced only for the FDI muscle, and not for the surround muscles. Unconditioned motor evoked potential sizes were increased in all muscles during FDI muscle tonic activation as compared with rest, despite background electromyography activity increasing only for the FDI muscle. Our study suggests that the cerebellum may play an important role in selective tonic finger movement by reducing its inhibition in the motor cortex only for the relevant agonist muscle.

  8. Muscle Deoxygenation Causes Muscle Fatigue

    NASA Technical Reports Server (NTRS)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

    1999-01-01

    Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

  9. Muscle disorder

    MedlinePlus

    Myopathic changes; Myopathy; Muscle problem ... Blood tests sometimes show abnormally high muscle enzymes. If a muscle disorder might also affect other family members, genetic testing may be done. When someone has symptoms and signs ...

  10. Muscle aches

    MedlinePlus

    ... common cause of muscle aches and pain is fibromyalgia , a condition that causes tenderness in your muscles ... imbalance, such as too little potassium or calcium Fibromyalgia Infections, including the flu, Lyme disease , malaria , muscle ...

  11. Effects of button position on a soft keyboard: Muscle activity, touch time, and discomfort in two-thumb text entry.

    PubMed

    Chang, Joonho; Choi, Bori; Tjolleng, Amir; Jung, Kihyo

    2017-04-01

    Intensive use of the thumbs for text entry on smartphones may contribute to discomfort, pain, or musculoskeletal disorders. This study investigated the effect of twenty-five button positions (5 rows × 5 columns) on a soft keyboard for two-thumb entry. Two experiments measured muscle activity, touch time, and discomfort as a function of the button positions. In Phase I, the muscle activities of two intrinsic (abductor pollicis brevis and first dorsal interossei) and two extrinsic (abductor pollicis longus and extensor digitorum communis) muscles associated with thumb motions were observed for ten college students (age: 24.2). In Phase II, touch time and discomfort were measured for 40 college students (age: 23.6). The results demonstrated that the %MVCs of the intrinsic muscles significantly increased when the thumbs flexed and abducted. Also, the button positions near the rest positions of the thumbs resulted in significantly shorter touch times (0.66 s) and lower discomfort ratings (0.70 pt) than their peripheral buttons (0.76 s; 2.29 pt).

  12. Weak lensing and cosmology

    NASA Astrophysics Data System (ADS)

    Lombardi, Marco; Bertin, Giuseppe

    1999-02-01

    Recently, it has been shown that it is possible to reconstruct the projected mass distribution of a cluster from weak lensing provided that both the geometry of the universe and the probability distribution of galaxy redshifts are known; actually, when additional photometric data are taken to be available, the galaxy redshift distribution could be determined jointly with the cluster mass from the weak lensing analysis. In this paper we develop, in the spirit of a ``thought experiment,'' a method to constrain the geometry of the universe from weak lensing, provided that the redshifts of the source galaxies are measured. The quantitative limits and merits of the method are discussed analytically and with a set of simulations, in relation to point estimation, interval estimation, and test of hypotheses for homogeneous Friedmann-Lema\\^\\i tre models. The constraints turn out to be significant when a few thousand source galaxies are used.

  13. Partial muscle carnitine palmitoyltransferase-A deficiency

    SciTech Connect

    Ross, N.S.; Hoppel, C.L.

    1987-01-02

    After initiation of ibuprofen therapy, a 45-year-old woman developed muscle weakness and tenderness with rhabdomyolysis, culminating in respiratory failure. A muscle biopsy specimen showed a vacuolar myopathy, and markedly decreased muscle carnitine content and carnitine palmitoyltransferase activity. Following recovery, muscle carnitine content was normal but carnitine palmitoyltransferase activity was still abnormally low. The ratio of palmitoyl-coenzyme A plus carnitine to palmitoylcarnitine oxidation by muscle mitochondria isolated from the patient was markedly decreased. The authors conclude that transiently decreased muscle carnitine content interacted with partial deficiency of carnitine palmitoyltransferase-A to produce rhabdomyolysis and respiratory failure and that ibuprofen may have precipitated the clinical event.

  14. Influence of Lateral Muscle Loading in the Proximal Femur after Fracture Stabilization with a Trochanteric Gamma Nail (TGN)

    NASA Astrophysics Data System (ADS)

    Sitthiseripratip, Kriskrai; Mahaisavariya, Banchong; Suwanprateeb, Jintamai; Bohez, Erik; Vander Sloten, Jos

    The purpose of this study was to investigate the influence of lateral muscle loading on the stress/strain distributions of the trochanteric Gamma nail (TGN) fixation within the healed, trochanteric and subtrochanteric femoral fractures by means of a finite element method. The effect of three muscle groups, the abductors (ABD), the vastus lateralis (VL) and the iliotibial band (ITB), were investigated. The analytical results showed that addition of lateral muscle forces, iliotibial band and vastus lateralis, produced compensation of forces and reduction of bending moments in the bone and in the trochanteric Gamma nail especially in the lateral aspect. The iliotibial band produced a higher impact as compared to the vastus lateralis. Therefore in the finite element analysis of the proximal femur with the trochanteric Gamma nail fracture fixation should include the lateral muscle forces to simulate load condition with maximal physiological relevance to the closed nailing technique.

  15. Nuclear positioning in muscle development and disease

    PubMed Central

    Folker, Eric S.; Baylies, Mary K.

    2013-01-01

    Muscle disease as a group is characterized by muscle weakness, muscle loss, and impaired muscle function. Although the phenotype is the same, the underlying cellular pathologies, and the molecular causes of these pathologies, are diverse. One common feature of many muscle disorders is the mispositioning of myonuclei. In unaffected individuals, myonuclei are spaced throughout the periphery of the muscle fiber such that the distance between nuclei is maximized. However, in diseased muscles, the nuclei are often clustered within the center of the muscle cell. Although this phenotype has been acknowledged for several decades, it is often ignored as a contributor to muscle weakness. Rather, these nuclei are taken only as a sign of muscle repair. Here we review the evidence that mispositioned myonuclei are not merely a symptom of muscle disease but also a cause. Additionally, we review the working models for how myonuclei move from two different perspectives: from that of the nuclei and from that of the cytoskeleton. We further compare and contrast these mechanisms with the mechanisms of nuclear movement in other cell types both to draw general themes for nuclear movement and to identify muscle-specific considerations. Finally, we focus on factors that can be linked to muscle disease and find that genes that regulate myonuclear movement and positioning have been linked to muscular dystrophy. Although the cause-effect relationship is largely speculative, recent data indicate that the position of nuclei should no longer be considered only a means to diagnose muscle disease. PMID:24376424

  16. Cerebellar brain inhibition in the target and surround muscles during voluntary tonic activation

    PubMed Central

    Panyakaew, Pattamon; Cho, Hyun Joo; Srivanitchapoom, Prachaya; Popa, Traian; Wu, Tianxia; Hallett, Mark

    2016-01-01

    Motor surround inhibition is the neural mechanism that selectively favors the contraction of target muscles and inhibits nearby muscles to prevent unwanted movements. This inhibition was previously reported at the onset of a movement, but not during a tonic contraction. Cerebellar brain inhibition (CBI) is reduced in active muscles during tonic activation; however, it has not been studied in the surround muscles. CBI was evaluated in the first dorsal interosseus (FDI) as the target muscle, and the abductor digiti minimi (ADM), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) as surround muscles during rest and tonic activation of FDI in fourteen subjects. Cerebellar stimulation was performed under MRI-guided neuronavigation targeting lobule VIII of the cerebellar hemisphere. Stimulus intensities for cerebellar stimulation were based on the resting motor cortex threshold (RMT) and adjusted for the depth difference between the cerebellar and motor cortices. We used 90% to 120% of adjusted RMT as the conditioning stimulus intensity during rest. The intensity that generated the best CBI at rest in the FDI was selected for use during tonic activation. During selective tonic activation of FDI, CBI was significantly reduced only for FDI but not for the surround muscles. Unconditioned MEP sizes were increased in all muscles during FDI tonic activation compared to rest, despite background EMG activity increasing only for the FDI. Our study suggests that the cerebellum may play an important role in selective tonic finger movement by reducing its inhibition in the motor cortex only for the relevant agonist muscle. PMID:26900871

  17. Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy

    PubMed Central

    Rangel, Maria Luíza Sales; Sanchez, Tiago Arruda; Moreira, Filipe Azaline; Hoefle, Sebastian; Souto, Inaiacy Bittencourt; da Cunha, Antônio José Ledo Alves

    2015-01-01

    Background Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS). Methods In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1) the representations of the hand flexor digitorum superficialis (FDS), as well as of the intrinsic hand muscles abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05. Findings Dynamometry performance of the patients’ most affected hand (MAH), was worse than that of the less affected hand (LAH) and of healthy controls participants (p = 0.031), confirming handgrip impairment. Motor threshold (MT) of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP) amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy. Conclusion Decreased

  18. Weaknesses in Underperforming Schools

    ERIC Educational Resources Information Center

    van de Grift, Wim; Houtveen, Thoni

    2007-01-01

    In some Dutch elementary schools, the average performance of students over several years is significantly below the level that could be expected of them. This phenomenon is known as "underperformance." The most important identifiable weaknesses that go along with this phenomenon are that (a) learning material offered at school is…

  19. Impairment of muscle force transmission in spastic-paretic muscles of stroke survivors.

    PubMed

    Xiaogang Hu; Afsharipour, Babak; Rymer, William Zev; Suresh, Nina L

    2016-08-01

    Hemispheric stroke survivors tend to have persistent motor impairments, with muscle weakness and muscle spasticity observed concurrently in the affected muscles. The objective of this preliminary study was to identify whether impairment of muscle force transmission could contribute to weakness in spastic-paretic muscles of chronic stroke survivors. To characterize the efficiency of the transmission of muscle forces to the tendon, we activated biceps brachii muscle electrically by stimulating the musculocutaneous nerve with maximum current. The ratio between the elicited maximum twitch force amplitude and the maximum M-wave peak-peak amplitude was calculated as a measure of the efficiency of force transmission. Based on the preliminary results of two stroke survivors, we show that the Force/M-wave ratio was reduced in the affected biceps brachii muscles in comparison with the contralateral muscles, indicating a potential impairment in the muscle force transmission in the affected muscles. Our findings suggest that disrupted muscle force transmission to the tendon could contribute to weakness in spastic muscles of chronic stroke survivors.

  20. Weak Finsler structures and the Funk weak metric

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Athanase; Troyanov, Marc

    2009-04-01

    We discuss general notions of metrics and of Finsler structures which we call weak metrics and weak Finsler structures. Any convex domain carries a canonical weak Finsler structure, which we call its tautological weak Finsler structure. We compute distances in the tautological weak Finsler structure of a domain and we show that these are given by the so-called Funk weak metric. We conclude the paper with a discussion of geodesics, of metric balls and of convexity properties of the Funk weak metric.

  1. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  2. Composite weak bosons

    SciTech Connect

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  3. Weakly supervised glasses removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhicheng; Zhou, Yisu; Wen, Lijie

    2015-03-01

    Glasses removal is an important task on face recognition, in this paper, we provide a weakly supervised method to remove eyeglasses from an input face image automatically. We choose sparse coding as face reconstruction method, and optical flow to find exact shape of glasses. We combine the two processes iteratively to remove glasses more accurately. The experimental results reveal that our method works much better than these algorithms alone, and it can remove various glasses to obtain natural looking glassless facial images.

  4. Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch

    PubMed Central

    Kelly, Luke A.; Cresswell, Andrew G.; Racinais, Sebastien; Whiteley, Rodney; Lichtwark, Glen

    2014-01-01

    The human foot is characterized by a pronounced longitudinal arch (LA) that compresses and recoils in response to external load during locomotion, allowing for storage and return of elastic energy within the passive structures of the arch and contributing to metabolic energy savings. Here, we examine the potential for active muscular contribution to the biomechanics of arch deformation and recoil. We test the hypotheses that activation of the three largest plantar intrinsic foot muscles, abductor hallucis, flexor digitorum and quadratus plantae is associated with muscle stretch in response to external load on the foot and that activation of these muscles (via electrical stimulation) will generate sufficient force to counter the deformation of LA caused by the external load. We found that recruitment of the intrinsic foot muscles increased with increasing load, beyond specific load thresholds. Interestingly, LA deformation and muscle stretch plateaued towards the maximum load of 150% body weight, when muscle activity was greatest. Electrical stimulation of the plantar intrinsic muscles countered the deformation that occurred owing to the application of external load by reducing the length and increasing the height of the LA. These findings demonstrate that these muscles have the capacity to control foot posture and LA stiffness and may provide a buttressing effect during foot loading. This active arch stiffening mechanism may have important implications for how forces are transmitted during locomotion and postural activities as well as consequences for metabolic energy saving. PMID:24478287

  5. Evaluation of muscle hyperactivity of the grimacing muscles by unilateral tight eyelid closure and stapedius muscle tone.

    PubMed

    Shiba, Masato; Matsuo, Kiyoshi; Ban, Ryokuya; Nagai, Fumio

    2012-10-01

    Muscle hyperactivity of grimacing muscles, including the orbicularis oculi and corrugator supercilii muscles that cause crow's feet and a glabellar frown line with ageing, cannot be accurately evaluated by surface observation. In 71 subjects, this study investigated the extent to which grimacing muscles are innervated by the bilateral motor cortices, whether the corticofacial projection to the grimacing muscles affects the facially innervated stapedius muscle tone by measuring static compliance of the tympanic membrane, and whether unilateral tight eyelid closure with contraction of the grimacing muscles changes static compliance. Unilateral tight eyelid closure and its subsequent change in the contralateral vertical medial eyebrow position revealed that motor neurons of the orbicularis oculi and corrugator supercilii muscles were innervated by the bilateral motor cortices with weak-to-strong contralateral dominance. The orbicularis oculi, corrugator supercilii, and stapedius muscles innervated by the bilateral motor cortices had increased muscle hyperactivity, which lowered the vertical medial eyebrow position and decreased the static compliance of the tympanic membrane more than those innervated by the unilateral motor cortex. Unilateral enhanced tight eyelid closure with contraction of the grimacing muscles in certain subjects ipsilaterally decreased the static compliance with increased contraction of the stapedius muscle, which probably occurs to immobilise the tympanic membrane and protect the inner ear from loud sound. Evaluation of unilateral tight eyelid closure and the subsequent change in the contralateral vertical medial eyebrow position as well as a measurement of the static compliance for the stapedius muscle tone has revealed muscle hyperactivity of grimacing muscles.

  6. Amyloidotic muscle pseudohypertrophy: case report.

    PubMed

    Scola, R H; Werneck, L C; Ramos, C S; Pasquini, R; Graf, H; Arruda, W O

    2001-09-01

    The authors report one case of amyloidosis associated with muscular pseudohypertrophy in a 46-year-old woman, who developed weakness, macroglossia and muscle hypertrophy associated with primary systemic amyloidosis. Electromyography showed a myopathic pattern and bilateral carpal tunnel syndrome. The muscle biopsy presented with a type I and II fiber hypertrophy and infiltration of amyloid material in the interstitious space and artery walls. She underwent bone marrow transplantation with stabilization and subjective improvement of the clinical picture.

  7. Atypical presentation of GNE myopathy with asymmetric hand weakness.

    PubMed

    de Dios, John Karl L; Shrader, Joseph A; Joe, Galen O; McClean, Jeffrey C; Williams, Kayla; Evers, Robert; Malicdan, May Christine V; Ciccone, Carla; Mankodi, Ami; Huizing, Marjan; McKew, John C; Bluemke, David A; Gahl, William A; Carrillo-Carrasco, Nuria

    2014-12-01

    GNE myopathy is a rare autosomal recessive muscle disease caused by mutations in GNE, the gene encoding the rate-limiting enzyme in sialic acid biosynthesis. GNE myopathy usually manifests in early adulthood with distal myopathy that progresses slowly and symmetrically, first involving distal muscles of the lower extremities, followed by proximal muscles with relative sparing of the quadriceps. Upper extremities are typically affected later in the disease. We report a patient with GNE myopathy who presented with asymmetric hand weakness. He had considerably decreased left grip strength, atrophy of the left anterior forearm and fibro-fatty tissue replacement of left forearm flexor muscles on T1-weighted magnetic resonance imaging. The patient was an endoscopist and thus the asymmetric hand involvement may be associated with left hand overuse in daily repetitive pinching and gripping movements, highlighting the possible impact of environmental factors on the progression of genetic muscle conditions.

  8. Experimental muscle pain increases variability of neural drive to muscle and decreases motor unit coherence in tremor frequency band

    PubMed Central

    Yavuz, Utku Ş.; Negro, Francesco; Falla, Deborah

    2015-01-01

    It has been observed that muscle pain influences force variability and low-frequency (<3 Hz) oscillations in the neural drive to muscle. In this study, we aimed to investigate the effect of experimental muscle pain on the neural control of muscle force at higher frequency bands, associated with afferent feedback (alpha band, 5–13 Hz) and with descending cortical input (beta band, 15–30 Hz). Single-motor unit activity was recorded, in two separate experimental sessions, from the abductor digiti minimi (ADM) and tibialis anterior (TA) muscles with intramuscular wire electrodes, during isometric abductions of the fifth finger at 10% of maximal force [maximum voluntary contraction (MVC)] and ankle dorsiflexions at 25% MVC. The contractions were repeated under three conditions: no pain (baseline) and after intramuscular injection of isotonic (0.9%, control) and hypertonic (5.8%, painful) saline. The results showed an increase of the relative power of both the force signal and the neural drive at the tremor frequency band (alpha, 5–13 Hz) between the baseline and hypertonic (painful) conditions for both muscles (P < 0.05) but no effect on the beta band. Additionally, the strength of motor unit coherence was lower (P < 0.05) in the hypertonic condition in the alpha band for both muscles and in the beta band for the ADM. These results indicate that experimental muscle pain increases the amplitude of the tremor oscillations because of an increased variability of the neural control (common synaptic input) in the tremor band. Moreover, the concomitant decrease in coherence suggests an increase in independent input in the tremor band due to pain. PMID:26019314

  9. Weakly broken galileon symmetry

    SciTech Connect

    Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo

    2015-09-01

    Effective theories of a scalar ϕ invariant under the internal galileon symmetryϕ→ϕ+b{sub μ}x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon’s quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  10. `Weak A' phenotypes

    PubMed Central

    Cartron, J. P.; Gerbal, A.; Hughes-Jones, N. C.; Salmon, C.

    1974-01-01

    Thirty-five weak A samples including fourteen A3, eight Ax, seven Aend, three Am and three Ae1 were studied in order to determine their A antigen site density, using an IgG anti-A labelled with 125I. The values obtained ranged between 30,000 A antigen sites for A3 individuals, and 700 sites for the Ae1 red cells. The hierarchy of values observed made it possible to establish a quantitative relationship between the red cell agglutinability of these phenotypes measured under standard conditions, and their antigen site density. PMID:4435836

  11. Muscle biopsy

    MedlinePlus

    ... Inflammatory diseases of muscle (such as polymyositis or dermatomyositis ) Diseases of the connective tissue and blood vessels ( ... disease that involves inflammation and a skin rash ( dermatomyositis ) Inherited muscle disorder ( Duchenne muscular dystrophy ) Inflammation of ...

  12. Diaphragm weakness in Charcot-Marie-Tooth disease.

    PubMed Central

    Laroche, C M; Carroll, N; Moxham, J; Stanley, N N; Evans, R J; Green, M

    1988-01-01

    Two patients are described with Charcot-Marie-Tooth disease and chronic peripheral neuropathy. Both had dyspnoea, orthopnoea, and evidence of severe diaphragm weakness. Expiratory muscle function was well preserved and abnormalities of gas exchange during sleep were only minor. PMID:3420560

  13. Modeling Muscles

    ERIC Educational Resources Information Center

    Goodwyn, Lauren; Salm, Sarah

    2007-01-01

    Teaching the anatomy of the muscle system to high school students can be challenging. Students often learn about muscle anatomy by memorizing information from textbooks or by observing plastic, inflexible models. Although these mediums help students learn about muscle placement, the mediums do not facilitate understanding regarding integration of…

  14. Amino Acid Sensing in Skeletal Muscle.

    PubMed

    Moro, Tatiana; Ebert, Scott M; Adams, Christopher M; Rasmussen, Blake B

    2016-11-01

    Aging impairs skeletal muscle protein synthesis, leading to muscle weakness and atrophy. However, the underlying molecular mechanisms remain poorly understood. Here, we review evidence that mammalian/mechanistic target of rapamycin complex 1 (mTORC1)-mediated and activating transcription factor 4 (ATF4)-mediated amino acid (AA) sensing pathways, triggered by impaired AA delivery to aged skeletal muscle, may play important roles in skeletal muscle aging. Interventions that alleviate age-related impairments in muscle protein synthesis, strength, and/or muscle mass appear to do so by reversing age-related changes in skeletal muscle AA delivery, mTORC1 activity, and/or ATF4 activity. An improved understanding of the mechanisms and roles of AA sensing pathways in skeletal muscle may lead to evidence-based strategies to attenuate sarcopenia.

  15. The Effects of a Transition to Minimalist Shoe Running on Intrinsic Foot Muscle Size.

    PubMed

    Johnson, A W; Myrer, J W; Mitchell, U H; Hunter, I; Ridge, S T

    2016-02-01

    A proposed benefit of minimalist shoe running is an increase in intrinsic foot muscle strength. This study examined change in intrinsic foot muscle size in runners transitioning to Vibram FiveFingers™ minimalist shoes compared to a control group running in traditional running shoes. We compare pre-transition size between runners who developed bone marrow edema to those who did not. 37 runners were randomly assigned to the Vibram FiveFingers™ group (n=18) or control group (n=19). Runners' bone marrow edema and intrinsic foot muscle size were measured at baseline and after 10 weeks. Total running volume was maintained by all runners. A significant increase in abductor hallucis cross-sectional area of 10.6% occurred in the Vibram FiveFingers™ group compared to the control group (p=0.01). There was no significant change in any of the other muscles examined (p>0.05). 8 of the Vibram FiveFingers™ runners, and 1 control runner developed bone marrow edema. Those who developed bone marrow edema, primarily women, had significantly smaller size in all assessed muscles (p≤0.05). Size of intrinsic foot muscles appears to be important in safely transitioning to minimalist shoe running. Perhaps intrinsic foot muscle strengthening may benefit runners wanting to transition to minimalist shoes.

  16. Comparative functional anatomy of hindlimb muscles and bones with reference to aquatic adaptation of the sea otter.

    PubMed

    Mori, Kent; Suzuki, Satoshi; Koyabu, Daisuke; Kimura, Junpei; Han, Sung-Yong; Endo, Hideki

    2015-05-01

    Although the sea otter (Enhydra lutris) is a complete aquatic species, spending its entire life in the ocean, it has been considered morphologically to be a semi-aquatic animal. This study aimed to clarify the unique hindlimb morphology and functional adaptations of E. lutris in comparison to other Mustelidae species. We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica). In comparison with the other 4 species, E. lutris possessed significantly larger gluteus, popliteus and peroneus muscles, but smaller adductor and ischiopubic muscles. The popliteus muscle may act as a medial rotator of the crus, and the peroneus muscle may act as an abductor of the fifth toe and/or the pronator of the foot. The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction. These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator. Therefore, we conclude that E. lutris is a complete aquatic animal, possessing differences in the proportions of the hindlimb muscles compared with those in other semi-aquatic and terrestrial mustelids.

  17. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  18. Pattern Differences of Small Hand Muscle Atrophy in Amyotrophic Lateral Sclerosis and Mimic Disorders

    PubMed Central

    Fang, Jia; Liu, Ming-Sheng; Guan, Yu-Zhou; Du, Hua; Li, Ben-Hong; Cui, Bo; Ding, Qing-Yun; Cui, Li-Ying

    2016-01-01

    Background: Amyotrophic lateral sclerosis (ALS) and some mimic disorders, such as distal-type cervical spondylotic amyotrophy (CSA), Hirayama disease (HD), and spinobulbar muscular atrophy (SBMA) may present with intrinsic hand muscle atrophy. This study aimed to investigate different patterns of small hand muscle involvement in ALS and some mimic disorders. Methods: We compared the abductor digiti minimi/abductor pollicis brevis (ADM/APB) compound muscle action potential (CMAP) ratios between 200 ALS patients, 95 patients with distal-type CSA, 88 HD patients, 43 SBMA patients, and 150 normal controls. Results: The ADM/APB CMAP amplitude ratio was significantly higher in the ALS patients (P < 0.001) than that in the normal controls. The ADM/APB CMAP amplitude ratio was significantly reduced in the patients with distal-type CSA (P < 0.001) and the HD patients (P < 0.001) compared with that in the normal controls. The patients with distal-type CSA had significantly lower APB CMAP amplitude than the HD patients (P = 0.004). The ADM/APB CMAP amplitude ratio was significantly lower in the HD patients (P < 0.001) than that in the patients with distal-type CSA. The ADM/APB CMAP amplitude ratio of the SBMA patients was similar to that of the normal controls (P = 0.862). An absent APB CMAP and an abnormally high ADM/APB CMAP amplitude ratio (≥4.5) were observed exclusively in the ALS patients. Conclusions: The different patterns of small hand muscle atrophy between the ALS patients and the patients with mimic disorders presumably reflect distinct pathophysiological mechanisms underlying different disorders, and may aid in distinguishing between ALS and mimic disorders. PMID:26996473

  19. Diaphragm weakness as a cause of breathlessness after anatomically distant surgery

    PubMed Central

    Moore, A; Moxham, J; Polkey, M

    2005-01-01

    The case histories are presented of two patients in whom breathlessness developed following surgery to an anatomically distant site. Respiratory muscle testing demonstrated diaphragm weakness in both patients. PMID:16135683

  20. Lifting the nebula: novel insights into skeletal muscle contractility.

    PubMed

    Ottenheijm, Coen A C; Granzier, Henk

    2010-10-01

    Nebulin is a giant protein and a constituent of the skeletal muscle sarcomere. The name of this protein refers to its unknown (i.e., nebulous) function. However, recent rapid advances reveal that nebulin plays important roles in the regulation of muscle contraction. When these functions of nebulin are compromised, muscle weakness ensues, as is the case in patients with nemaline myopathy.

  1. Change in Excitability of Corticospinal Pathway and GABA-Mediated Inhibitory Circuits of Primary Motor Cortex Induced by Contraction of Adjacent Hand Muscle.

    PubMed

    Jono, Yasutomo; Iwata, Yasuyuki; Mizusawa, Hiroki; Hiraoka, Koichi

    2016-11-01

    The present study examined whether the excitability of the corticospinal pathway and the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the tonically contracting hand muscle are changed by tonic contraction of the adjacent hand muscle. The motor evoked potential (MEP) and cortical silent period (CSP) in the tonically contracting hand muscle were obtained while the adjacent hand muscle was either tonically contracting or at rest. The MEP and CSP of the first dorsal interosseous (FDI) muscle elicited across the scalp sites where the MEP is predominantly elicited in the FDI muscle were decreased by tonic contraction of the abductor digiti minimi (ADM) muscle. The centers of the area of the MEP and the duration of the CSP in the FDI muscle elicited across the sites where the MEP is predominantly elicited in the FDI muscle were lateral to those in the FDI muscle elicited across the sites where the MEP is elicited in both the FDI and ADM muscles. They were also lateral to those in the ADM muscle elicited either across the sites where the MEP is predominantly elicited in the ADM muscle, or across the sites where the MEP is elicited in both the FDI and ADM muscles. The decrease in the corticospinal excitability and the excitability of the GABA-mediated inhibitory circuits of the primary motor cortex that project onto the corticospinal neurons in the FDI muscle may be due either to (1) the interaction between the activity of the lateral area of the FDI representation and the descending drive to the ADM muscle, or (2) the decreased susceptibility of the primary motor area that predominantly projects onto the corticospinal neurons in the FDI muscle, which also plays a role in independent finger movement when both the FDI and ADM muscles act together as synergists.

  2. Weak neutral current chemistry

    SciTech Connect

    Mohan, R.

    1996-07-01

    Metal cluster organic complexes, neither atomic nor solid but in analogy to atomic nuclei and to mesoscopic systems, have unusual dynamics and catalytic properties. Organo-metal clusters as quintessence prebiotic enzymes could have originated the homochirality of the molecules from achiral precursors, controlled from the atomic-nucleus, with the initial product itself serving subsequently as chiral auxiliary transferring and amplifying the chirality in the autocatalytic process now. High resolution spectroscopic studies of diatomic molecules beginning now may lead to upper estimates of the interaction strength of weak neutral currents (WNG) with valence electrons of metal clusters and suggest kinetic pathways to dynamic symmetry breaking in the asymmetric synthesis of chiral molecules. An estimate of 10{sup {minus}5} kT (thousand times larger than for radiolysis) for the parity violating energy (PVE) could be sufficient to run an entropy driven spin-catalyzed asymmetric synthesis. Expect then, wherever there are metal clusters in interstellar dust or under the sea chiral molecular production. {copyright} {ital 1996 American Institute of Physics.}

  3. Weak neutral current chemistry

    NASA Astrophysics Data System (ADS)

    Mohan, R.

    1996-07-01

    Metal cluster organic complexes, neither atomic nor solid but in analogy to atomic nuclei and to mesoscopic systems, have unusual dynamics and catalytic properties. Organo-metal clusters as quintessence prebiotic enzymes could have originated the homochirality of the molecules from achiral precursors, controlled from the atomic-nucleus, with the initial product itself serving subsequently as chiral auxiliary transferring and amplifying the chirality in the autocatalytic process now. High resolution spectroscopic studies of diatomic molecules beginning now may lead to upper estimates of the interaction strength of weak neutral currents (WNG) with valence electrons of metal clusters and suggest kinetic pathways to dynamic symmetry breaking in the asymmetric synthesis of chiral molecules. An estimate of 10-5 kT (thousand times larger than for radiolysis) for the parity violating energy (PVE) could be sufficient to run an entropy driven spin-catalyzed asymmetric synthesis. Expect then, wherever there are metal clusters in interstellar dust or under the sea chiral molecular production.

  4. Anomalous bilateral contribution of extensor pollicis longus and muscle fusion of the first compartment of the wrist.

    PubMed

    Rosa, Rodrigo César; de Oliveira, Kennedy Martinez; Léo, Jorge Alfredo; Elias, Bruno Adriano Borges; Dos Santos, Paulo Ricardo; de Santiago, Hildemberg Agostinho Rocha

    2016-01-01

    Knowledge of the anatomical variations of the muscles of the first dorsal compartments of the wrist is clinically relevant to De Quervain's tenosynovitis and to reconstructive surgeries. In the literature, there are many reports of the presence of multiple insertion tendons in the first dorsal compartment of the wrist, but few reports describe occurrences of fusion and muscle contributions. This case report describes an anomalous bilateral contribution of the extensor pollicis longus. This anomalous contribution was found through a slender auxiliary tendon that crossed laterally under the extensor retinaculum, entered the first dorsal compartment of the wrist and merged with the tendon of the extensor pollicis brevis muscle. In the same cadaver in which this contribution was present, there was atypical muscle fusion of the abductor pollicis longus muscle and extensor pollicis brevis muscle. In conclusion, anomalous bilateral contribution of the extensor pollicis longus muscle and atypical muscle fusion, concomitant with a variant insertion pattern, are the highlight of this case report. Furthermore, it is concluded that additional tendons may be effectively used in reconstructive surgeries, but that there is a need for knowledge of the possible numerical and positional variations of these tendons, with a view to making more effective surgical plans.

  5. Anomalous bilateral contribution of extensor pollicis longus and muscle fusion of the first compartment of the wrist

    PubMed Central

    Rosa, Rodrigo César; de Oliveira, Kennedy Martinez; Léo, Jorge Alfredo; Elias, Bruno Adriano Borges; dos Santos, Paulo Ricardo; de Santiago, Hildemberg Agostinho Rocha

    2016-01-01

    Knowledge of the anatomical variations of the muscles of the first dorsal compartments of the wrist is clinically relevant to De Quervain's tenosynovitis and to reconstructive surgeries. In the literature, there are many reports of the presence of multiple insertion tendons in the first dorsal compartment of the wrist, but few reports describe occurrences of fusion and muscle contributions. This case report describes an anomalous bilateral contribution of the extensor pollicis longus. This anomalous contribution was found through a slender auxiliary tendon that crossed laterally under the extensor retinaculum, entered the first dorsal compartment of the wrist and merged with the tendon of the extensor pollicis brevis muscle. In the same cadaver in which this contribution was present, there was atypical muscle fusion of the abductor pollicis longus muscle and extensor pollicis brevis muscle. In conclusion, anomalous bilateral contribution of the extensor pollicis longus muscle and atypical muscle fusion, concomitant with a variant insertion pattern, are the highlight of this case report. Furthermore, it is concluded that additional tendons may be effectively used in reconstructive surgeries, but that there is a need for knowledge of the possible numerical and positional variations of these tendons, with a view to making more effective surgical plans. PMID:27069895

  6. Contributions of muscles to mediolateral ground reaction force over a range of walking speeds.

    PubMed

    John, Chand T; Seth, Ajay; Schwartz, Michael H; Delp, Scott L

    2012-09-21

    Impaired control of mediolateral body motion during walking is an important health concern. Developing treatments to improve mediolateral control is challenging, partly because the mechanisms by which muscles modulate mediolateral ground reaction force (and thereby modulate mediolateral acceleration of the body mass center) during unimpaired walking are poorly understood. To investigate this, we examined mediolateral ground reaction forces in eight unimpaired subjects walking at four speeds and determined the contributions of muscles, gravity, and velocity-related forces to the mediolateral ground reaction force by analyzing muscle-driven simulations of these subjects. During early stance (0-6% gait cycle), peak ground reaction force on the leading foot was directed laterally and increased significantly (p<0.05) with walking speed. During early single support (14-30% gait cycle), peak ground reaction force on the stance foot was directed medially and increased significantly (p<0.01) with speed. Muscles accounted for more than 92% of the mediolateral ground reaction force over all walking speeds, whereas gravity and velocity-related forces made relatively small contributions. Muscles coordinate mediolateral acceleration via an interplay between the medial ground reaction force contributed by the abductors and the lateral ground reaction forces contributed by the knee extensors, plantarflexors, and adductors. Our findings show how muscles that contribute to forward progression and body-weight support also modulate mediolateral acceleration of the body mass center while weight is transferred from one leg to another during double support.

  7. Spinalis capitis, or an accessory paraspinous muscle?

    PubMed Central

    Martin, A

    1994-01-01

    A unilateral muscle, the location and dimensions of which do not exactly conform to existing descriptions, was found during dissection of the suboccipital region. The muscle in question extended from the spine and transverse process of the 6th cervical vertebra to the base of the skull. At its rostral attachment it blended with the insertion of the left rectus capitis posterior minor muscle on the inferior nuchal line. The caudal attachment arched over the semispinalis cervicis, separated from that muscle by an extensive venous complex. Medially, along the length of the muscle, weak fascial attachments to the ligamentum nuchae were present. Arterial branches from the occipital artery entered the muscle near its rostral end and nerve fibres and vascular channels from the lower cervical region entered the deep surface of the muscle. Images Figs 1-3 Fig. 4 PMID:7559114

  8. Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols.

    PubMed

    Kamke, Marc R; Nydam, Abbey S; Sale, Martin V; Mattingley, Jason B

    2016-04-01

    Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS25) or a decrease (PAS10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS25 applied to one muscle representation may be produced by simultaneously applying PAS25 or PAS10 to a nearby representation. In different experiments prototypical PAS25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS25 or PAS10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS10 also targeting the APB. In an additional control experiment PAS10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.

  9. The pectoral fin muscles of the coelacanth Latimeria chalumnae: Functional and evolutionary implications for the fin-to-limb transition and subsequent evolution of tetrapods.

    PubMed

    Miyake, Tsutomu; Kumamoto, Minayori; Iwata, Masamitsu; Sato, Ryuichi; Okabe, Masataka; Koie, Hiroshi; Kumai, Nori; Fujii, Kenichi; Matsuzaki, Koji; Nakamura, Chiho; Yamauchi, Shinya; Yoshida, Kosuke; Yoshimura, Kohtaroh; Komoda, Akira; Uyeno, Teruya; Abe, Yoshitaka

    2016-09-01

    To investigate the morphology and evolutionary origin of muscles in vertebrate limbs, we conducted anatomical dissections, computed tomography and kinematic analyses on the pectoral fin of the African coelacanth, Latimeria chalumnae. We discovered nine antagonistic pairs of pronators and supinators that are anatomically and functionally distinct from the abductor and adductor superficiales and profundi. In particular, the first pronator and supinator pair represents mono- and biarticular muscles; a portion of the muscle fibers is attached to ridges on the humerus and is separated into two monoarticular muscles, whereas, as a biarticular muscle, the main body is inserted into the radius by crossing two joints from the shoulder girdle. This pair, consisting of a pronator and supinator, constitutes a muscle arrangement equivalent to two human antagonistic pairs of monoarticular muscles and one antagonistic pair of biarticular muscles in the stylopod between the shoulder and elbow joints. Our recent kinesiological and biomechanical engineering studies on human limbs have demonstrated that two antagonistic pairs of monoarticular muscles and one antagonistic pair of biarticular muscles in the stylopod (1) coordinately control output force and force direction at the wrist and ankle and (2) achieve a contact task to carry out weight-bearing motion and maintain stable posture. Therefore, along with dissections of the pectoral fins in two lungfish species, Neoceratodus forsteri and Protopterus aethiopicus, we discuss the functional and evolutionary implications for the fin-to-limb transition and subsequent evolution of tetrapods. Anat Rec, 299:1203-1223, 2016. © 2016 Wiley Periodicals, Inc.

  10. Increased inspiratory and expiratory muscle strength following respiratory muscle strength training (RMST) in two patients with late-onset Pompe disease.

    PubMed

    Jones, Harrison N; Moss, Tronda; Edwards, Laurie; Kishnani, Priya S

    2011-11-01

    Respiratory muscle strength training (RMST) is an exercise-based intervention which targets respiratory muscle weakness. We implemented RMST in two patients with late-onset Pompe disease (LOPD), both who had received long-term enzyme replacement therapy and had severe respiratory weakness. Over 16-32 weeks, inspiratory muscle strength increased by 73-74%. Expiratory muscle strength increased 31-48% over 12-22 weeks. These findings suggest that RMST may increase respiratory muscle strength, even in the setting of LOPD and severe baseline weakness.

  11. Unexpected motor weakness following quadratus lumborum block for gynaecological laparoscopy.

    PubMed

    Wikner, M

    2017-02-01

    Quadratus lumborum block has recently been described as an effective and long-lasting analgesic strategy for various abdominal operations, including gynaecological laparoscopy. Despite evidence that the analgesic effect is mediated by indirect paravertebral block and that local anaesthetic spreads to the lumbar paravertebral space, there have been no reports to date of lower limb motor weakness. We present a patient with unilateral hip flexion and knee extension weakness leading to unplanned overnight admission following lateral quadratus lumborum block with 20 ml levobupivacaine 0.25%. The L2 dermatomal sensory loss and hip flexion weakness suggested spread to either the L2 paravertebral space or to the lumbar plexus, causing weakness of the psoas and iliacus muscles and possibly the quadriceps. The duration of motor block was approximately 18 h. This complication should be considered when performing the block, especially in the setting of day-case surgery.

  12. A single muscle moves a crustacean limb joint rhythmically by acting against a spring containing resilin

    PubMed Central

    Burrows, Malcolm

    2009-01-01

    Background The beating or fanning movements of three pairs of maxilliped flagella in crabs and crayfish modify exhalent gill currents while drawing water over chemoreceptors on the head. They play an integral part both in signalling by distributing urine odours, and in active chemosensation. Results The rhythmical maxilliped movements start with maxilliped 3 followed after a delay of 15 to 20 ms in shore crabs by maxilliped 2 and then maxilliped 1, at a frequency of 18 to 20 Hz in crabs and 10 to 13 Hz in signal crayfish. The contraction of a single abductor muscle controls the power stroke (abduction) of each flagellum, which is accompanied by flaring of feather-like setae which increase its surface area. No muscle can bring about the return stroke (adduction). Release of an isolated flagellum from an imposed abduction is followed by a rapid recoil to its resting adducted position. The relationship between the extent of abduction and the angular velocity of the return stroke indicates the operation of a spring. Blue fluorescence under UV light, and its dependence on the pH of the bathing medium, indicates that resilin is present at the joint between an exopodite and flagellum, at the annuli of a flagellum and at the base of the setae. Conclusion Resilin is progressively bent as a flagellum is abducted and resumes its natural shape when the joint recoils. Other distortions of the exopodites may also contribute to this spring-like action. The joint is therefore controlled by a single abductor muscle operating against a spring in which the elastic properties of resilin play a key role. PMID:19480647

  13. Structural alterations of skeletal muscle in copd

    PubMed Central

    Mathur, Sunita; Brooks, Dina; Carvalho, Celso R. F.

    2014-01-01

    Background: Chronic obstructive pulmonary disease (COPD) is a respiratory disease associated with a systemic inflammatory response. Peripheral muscle dysfunction has been well characterized in individuals with COPD and results from a complex interaction between systemic and local factors. Objective: In this narrative review, we will describe muscle wasting in people with COPD, the associated structural changes, muscle regenerative capacity and possible mechanisms for muscle wasting. We will also discuss how structural changes relate to impaired muscle function and mobility in people with COPD. Key Observations: Approximately 30–40% of individuals with COPD experience muscle mass depletion. Furthermore, muscle atrophy is a predictor of physical function and mortality in this population. Associated structural changes include a decreased proportion and size of type-I fibers, reduced oxidative capacity and mitochondrial density mainly in the quadriceps. Observations related to impaired muscle regenerative capacity in individuals with COPD include a lower proportion of central nuclei in the presence or absence of muscle atrophy and decreased maximal telomere length, which has been correlated with reduced muscle cross-sectional area. Potential mechanisms for muscle wasting in COPD may include excessive production of reactive oxygen species (ROS), altered amino acid metabolism and lower expression of peroxisome proliferator-activated receptors-gamma-coactivator 1-alpha mRNA. Despite a moderate relationship between muscle atrophy and function, impairments in oxidative metabolism only seems weakly related to muscle function. Conclusion: This review article demonstrates the cellular modifications in the peripheral muscle of people with COPD and describes the evidence of its relationship to muscle function. Future research will focus on rehabilitation strategies to improve muscle wasting and maximize function. PMID:24678302

  14. Intestinal Transport of Weak Electrolytes

    PubMed Central

    Jackson, Michael J.; Shiau, Yih-Fu; Bane, Susan; Fox, Margaret

    1974-01-01

    A study has been made of the transmural fluxes of benzoic, phenylacetic, and pentanoic acids, benzylamine, hexylamine, and D-amphetamine across rat jejunum incubated in vitro. The M to S fluxes of the weak acids were greater than their corresponding S to M fluxes, and the S to M fluxes of the weak bases were larger than their M to S fluxes. These patterns of asymmetric movements were observed when the transmural electrical potential difference was clamped at 0 mV, and when the pH values of the mucosal and serosal fluids were identical. The effects of a weak acid on the fluxes of other weak electrolytes were qualitatively similar when the effector weak acid was added to the mucosal fluid, and when it was added to the serosal fluid. But the effects of a weak base on the fluxes of other weak electrolytes were dependent upon its location, and the interactions observed when the effector weak base was added to the mucosal fluid were qualitatively different than those seen when it was added to the serosal fluid. The interactions between weak electrolytes could readily be explained in terms of the function of a system of three compartments in series, in which the pH of the intermediate compartment is greater than that of the bulk phases. But these observations could not be explained in terms of an analogous system involving an intermediate compartment of low pH, or in terms of a carrier mediated system. The transport function of the three-compartment system can be described in the form of an equation, and it is found that a pH difference of less than 0.5 unit may explain our observations on weak electrolyte transport. PMID:4812635

  15. Thyroarytenoid muscle activity during hypocapnic central apneas in awake nonsedated lambs.

    PubMed

    Kianicka, I; Leroux, J F; Praud, J P

    1994-03-01

    In this study, we examined whether the glottis is open or closed during central apnea and the effect of arterial PO2 (PaO2) on this control. We hyperventilated nine 11- to 30-day-old awake nonsedated lambs via a tracheostomy for 1 min to induce central apnea. Four gas mixtures (8, 15, 21, and 30% O2) were used. At the end of the hyperventilation period, the lambs were allowed to breathe spontaneously through intact upper airways. Using a pneumotachograph attached to a face mask, we measured airflow, and we continuously recorded electromyographic (EMG) activity of the thyroarytenoid (TA), the main glottic adductor muscle. We also studied the lateral cricoarytenoid muscle (LCA, laryngeal adductor), the posterior cricoarytenoid muscle (PCA, laryngeal abductor), the cricothyroid muscle (CT), and the diaphragm. We found that hyperventilation consistently induced hypocapnic central apnea in all nine lambs in hyperoxic conditions [30% inspiratory fraction of O2 (FIO2)], in eight of nine lambs in normoxia or mild hypoxia (15 and 21% FIO2), and in four of seven lambs in hypoxia (8% FIO2). During baseline room air breathing, there was no glottic adductor muscle expiratory EMG activity or expiratory airflow braking. Continuous TA EMG activity began early during hyperventilation and continued throughout the central apnea, regardless of PaO2. The first subsequent breathing efforts were marked by expiratory flow braking and expiratory activity of the TA. The LCA and the TA demonstrated the same EMG activity pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Experimental investigations of weak definite and weak indefinite noun phrases.

    PubMed

    Klein, Natalie M; Gegg-Harrison, Whitney M; Carlson, Greg N; Tanenhaus, Michael K

    2013-08-01

    Definite noun phrases typically refer to entities that are uniquely identifiable in the speaker and addressee's common ground. Some definite noun phrases (e.g., the hospital in Mary had to go the hospital and John did too) seem to violate this uniqueness constraint. We report six experiments that were motivated by the hypothesis that these "weak definite" interpretations arise in "incorporated" constructions. Experiments 1-3 compared nouns that seem to allow for a weak definite interpretation (e.g., hospital, bank, bus, radio) with those that do not (e.g., farm, concert, car, book). Experiments 1 and 2 used an instruction-following task and picture-judgment task, respectively, to demonstrate that a weak definite need not uniquely refer. In Experiment 3 participants imagined scenarios described by sentences such as The Federal Express driver had to go to the hospital/farm. Scenarios following weak definite noun phrases were more likely to include conventional activities associated with the object, whereas following regular nouns, participants were more likely to imagine scenarios that included typical activities associated with the subject; similar effects were observed with weak indefinites. Experiment 4 found that object-related activities were reduced when the same subject and object were used with a verb that does not license weak definite interpretations. In Experiment 5, a science fiction story introduced an artificial lexicon for novel concepts. Novel nouns that shared conceptual properties with English weak definite nouns were more likely to allow weak reference in a judgment task. Experiment 6 demonstrated that familiarity for definite articles and anti-familiarity for indefinite articles applies to the activity associated with the noun, consistent with predictions made by the incorporation analysis.

  17. Experimental investigations of weak definite and weak indefinite noun phrases

    PubMed Central

    Klein, Natalie M.; Gegg-Harrison, Whitney M.; Carlson, Greg N.; Tanenhaus, Michael K.

    2013-01-01

    Definite noun phrases typically refer to entities that are uniquely identifiable in the speaker and addressee’s common ground. Some definite noun phrases (e.g. the hospital in Mary had to go the hospital and John did too) seem to violate this uniqueness constraint. We report six experiments that were motivated by the hypothesis that these “weak definite” interpretations arise in “incorporated” constructions. Experiments 1-3 compared nouns that seem to allow for a weak definite interpretation (e.g. hospital, bank, bus, radio) with those that do not (e.g. farm, concert, car, book). Experiments 1 and 2 used an instruction-following task and picture-judgment task, respectively, to demonstrate that a weak definite need not uniquely refer. In Experiment 3 participants imagined scenarios described by sentences such as The Federal Express driver had to go to the hospital/farm. The imagined scenarios following weak definite noun phrases were more likely to include conventional activities associated with the object, whereas following regular nouns, participants were more likely to imagine scenarios that included typical activities associated with the subject; similar effects were observed with weak indefinites. Experiment 4 found that object-related activities were reduced when the same subject and object were used with a verb that does not license weak definite interpretations. In Experiment 5, a science fiction story introduced an artificial lexicon for novel concepts. Novel nouns that shared conceptual properties with English weak definite nouns were more likely to allow weak reference in a judgment task. Experiment 6 demonstrated that familiarity for definite articles and anti- familiarity for indefinite articles applies to the activity associated with the noun, consistent with predictions made by the incorporation analysis. PMID:23685208

  18. Muscle atrophy

    MedlinePlus

    ... damage caused by injury, diabetes, toxins, or alcohol Polio ( poliomyelitis ) Spinal cord injury Although people can adapt to ... Guillain-Barré syndrome Hypotonia Muscle cramps Muscular dystrophy Polio Review Date 1/5/2016 Updated by: Joseph ...

  19. Getting Muscles

    MedlinePlus

    ... muscular as a superhero or your favorite professional athlete? Well, the big muscles you're thinking about ... Superheroes, of course, aren't real, and professional athletes are grownups, whose bodies are different from kids' ...

  20. Muscle twitching

    MedlinePlus

    ... patient with neurologic disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: ... Selcen D. Muscle diseases. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: ...

  1. Muscle biopsy findings in inflammatory myopathies.

    PubMed

    Dalakas, Marinos C

    2002-11-01

    The inflammatory myopathies encompass a heterogeneous group of acquired muscle diseases characterized clinically, by muscle weakness, and histologically, by inflammatory infiltrates within the skeletal muscles. The group of these myopathies comprise three major and discrete subsets: polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM). Each subset retains its characteristic clinical, immunopathologic, and morphologic features regardless of whether it occurs separately or in connection with other systemic diseases. Although the diagnosis of these disorders is based on the combination of clinical examination, electromyographic data, serum muscle enzyme levels, various autoantibodies, and the muscle biopsy findings, the muscle biopsy offers the most definitive diagnostic information in the majority of the cases. This article summarizes the main histologic features that characterize PM, DM, or IBM and emphasizes the main pitfalls associated with interpretation of the biopsies.

  2. Weak-shock reflection factors

    SciTech Connect

    Reichenbach, H.; Kuhl, A.L.

    1993-09-07

    The purpose of this paper is to compare reflection factors for weak shocks from various surfaces, and to focus attention on some unsolved questions. Three different cases are considered: square-wave planar shock reflection from wedges; square-wave planar shock reflection from cylinders; and spherical blast wave reflection from a planar surface. We restrict ourselves to weak shocks. Shocks with a Mach number of M{sub O} < 1.56 in air or with an overpressure of {Delta}{sub PI} < 25 psi (1.66 bar) under normal ambient conditions are called weak.

  3. Imaging of skeletal muscle in vitamin D deficiency

    PubMed Central

    Bignotti, Bianca; Cadoni, Angela; Martinoli, Carlo; Tagliafico, Alberto

    2014-01-01

    Elderly people are prone to accidental falls and one of the main risk factor is considered muscle weakness. Several studies focused on muscle weakness and muscle morphology changes in the elderly that may be associated with vitamin D deficiency. The prevalence of vitamin D deficiency is higher than previously though representing an important issue for public health and prevention. There is an increased interest in vitamin D effects in skeletal muscle and imaging modalities are particularly involved in this field. In patients with vitamin D deficiency, ultrasound, computed tomography, densitometry and magnetic resonance imaging (MRI) can efficiently describe changes in muscle morphology and size. Moreover, new imaging modalities, such as MRI spectroscopy, may improve knowledge about the metabolic effects of vitamin D in skeletal muscle. In this narrative review we will discuss the role of skeletal muscle imaging in vitamin D-deficient individuals. The aim of this paper is to improve and encourage the role of radiologists in this field. PMID:24778774

  4. The anatomy and function of the gluteus minimus muscle.

    PubMed

    Beck, M; Sledge, J B; Gautier, E; Dora, C F; Ganz, R

    2000-04-01

    In order to investigate the functional anatomy of gluteus minimus we dissected 16 hips in fresh cadavers. The muscle originates from the external aspect of the ilium, between the anterior and inferior gluteal lines, and also at the sciatic notch from the inside of the pelvis where it protects the superior gluteal nerve and artery. It inserts anterosuperiorly into the capsule of the hip and continues to its main insertion on the greater trochanter. Based on these anatomical findings, a model was developed using plastic bones. A study of its mechanics showed that gluteus minimus acts as a flexor, an abductor and an internal or external rotator, depending on the position of the femur and which part of the muscle is active. It follows that one of its functions is to stabilise the head of the femur in the acetabulum by tightening the capsule and applying pressure on the head. Careful preservation or reattachment of the tendon of gluteus minimus during surgery on the hip is strongly recommended.

  5. Electromyographic study of polysynaptic responses from muscles not supplied by the stimulated nerve: preliminary report.

    PubMed

    Vernea, J

    1978-01-01

    15 subjects with normal neurological examinations, 7 hemiplegic patients, 5 patients with dementia and 4 with Parkinsonism were examined. A 1msec duration pulse below the pain threshold was applied to the median and ulnar nerves at the elbow and wrist. The activities of the biceps, triceps, flexor carpi radialis, forearm extensors and abductor pollicis brevis were recorded with surface electrodes. The most frequently observed response in normal subjects and hemiplegic patients occurred in the biceps, and had a latency of about 30msec. The other frequently elicited response in normal subjects and hemiplegic patients was in the forearm extensors. Recovery curves were obtained for the biceps response. A significant difference between normal subjects and hemiplegic patients was found. In the patients suffering from Parkinsonism, as well as in demented patients, one could record easily polysynpatic reflexes from other forearm muscles. This suggests the presence of basal ganglia damage in atrophic dementias.

  6. Weak interactions and presupernova evolution

    SciTech Connect

    Aufderheide, M.B. State Univ. of New York . Dept. of Physics)

    1991-02-19

    The role of weak interactions, particularly electron capture and {beta}{sup {minus}} decay, in presupernova evolution is discussed. The present uncertainty in these rates is examined and the possibility of improving the situation is addressed. 12 refs., 4 figs.

  7. Weak Deeply Virtual Compton Scattering

    SciTech Connect

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2007-03-01

    We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

  8. Precision metrology using weak measurements.

    PubMed

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A

    2015-05-29

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  9. Relationship between function of masticatory muscle in mouse and properties of muscle fibers.

    PubMed

    Abe, Shinichi; Hiroki, Emi; Iwanuma, Osamu; Sakiyama, Koji; Shirakura, Yoshitaka; Hirose, Daiki; Shimoo, Yoshiaki; Suzuki, Masashi; Ikari, Yasutoyo; Kikuchi, Ryusuke; Ide, Yoshinobu; Yoshinari, Masao

    2008-05-01

    Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.

  10. Human jaw muscle strength and size in relation to limb muscle strength and size.

    PubMed

    Raadsheer, M C; Van Eijden, T M G J; Van Ginkel, F C; Prahl-Andersen, B

    2004-10-01

    The aim of the present study was to investigate to what extent general factors (e.g. genotype, hormones) and factors at the craniofacial level (e.g. craniofacial size, jaw muscle architecture) contribute to the size and strength of the jaw muscles. A strong relationship of jaw muscle size and strength with that of other muscles would argue for general influences, whereas a weak relationship would argue for craniofacial influences. In 121 adult individuals, moments of maximal bite force, arm flexion force and leg extension force were measured. In addition, thicknesses of jaw muscles, arm flexor muscles and leg extensor muscles were measured using ultrasound. Relationships were assessed by using a principal component analysis. In females, one component was found in which all force moments were represented. Bite force moment, however, loaded very low. In males, two components were found. One component loaded for arm flexion and leg extension moments, the other loaded for bite force moments. In both females and males, only one component was found for the muscle thicknesses in which all muscle groups loaded similarly. It was concluded that the size of the jaw muscles was significantly related to the size of the limb muscles, suggesting that they were both subject to the same general influences. Maximal voluntary bite force moments were not significantly related to the moments of the arm flexion and leg extension forces, suggesting that besides the general influence on the muscle size, variation in bite force moment was also influenced by local variables, such as craniofacial morphology.

  11. Differentiation of motor cortical representation of hand muscles by navigated mapping of optimal TMS current directions in healthy subjects

    PubMed Central

    Bashir, Shahid; Perez, Jennifer; Horvath, Jared Cooney; Pascual-Leone, Alvaro

    2013-01-01

    The precision of navigated transcranial magnetic stimulation (TMS) to map the human primary motor cortex may be effected the direction of TMS-induced current in the brain as determined by the orientation of the stimulation coil. In this study, we investigated the effect of current directionality on motor output mapping using navigated brain stimulation (NBS). Our goal was to determine the optimal coil orientation (and, thus, induced brain current) to activate hand musculature representations relative to each subject’s unique neuroanatomical landmarks. We studied motor output maps for the first dorsal interosseous (FDI), abductor pollicis brevis (APB), and abductor digiti minimi (ADM) muscles in 10 normal volunteers. Monopolar current pulses were delivered through a figure-of-eight shaped TMS coil and motor evoked potentials (MEPs) were recorded using electromyography (EMG). At each targeted brain region, we systematically rotated the TMS coil to determine the direction of induced current in the brain for induction of the largest MEPs. These optimal current directions were expressed as an angle relative to each subject’s central sulcus. Consistency of the optimal current direction was assessed by repeating the entire mapping procedure on two different occasions across subjects. We demonstrate that systematic optimization of current direction as guided by MRI based neuronavigation improves the resolution of cortical output motor mapping with TMS. PMID:23912579

  12. Fast and singular muscle responses initiate the startle response of Pantodon buchholzi (Osteoglossomorpha).

    PubMed

    Starosciak, A K; Kalola, R P; Perkins, K P; Riley, J A; Saidel, W M

    2008-01-01

    The startle response of Pantodon buchholzi, the African butterfly fish, is a complete or incomplete ballistic jump resulting from abduction of the pectoral fins. This study analyzed the neuromuscular basis for such a jump by recording in vivo electromyograms (emgs) from the muscles of abduction, the muscularis abductor superficialis (MAS) and the muscularis abductor profundus (MAP). The motor neurons innervating the MAS muscle were localized by retrograde transport of biocytin. The latency between stimulus and the evoked emg in the MAS was less than 5 ms; the latency of the MAP was about 6.5 ms. A single emg was recorded per jump. High speed video demonstrated that onset of a startle movement began within 10 ms of the onset of fin abduction. The emg associated with this movement is short (<2 ms) and followed by a variably-shaped, slower and smaller potential of 10-30 ms duration. The brief period between stimulus and startle response of Pantodon suggests a Mauthner neuron-related response, only with the behavior occurring in the vertical plane. The MAS may act only in a startle response, whereas the MAP might have a role in other behaviors. Elicited jumping habituates after a single trial. Electrophysiological evidence is presented indicating that the innervating motor neurons are suppressed for seconds following a stimulus. The neurons innervating the MAS are located at the medullary-spinal cord junction and possess an average radius of approximately 17.9 mum. These fish have been historically described as 'fresh water' flying fish. As a single emg occurs per startle response, repetitive pectoral activity generating flying cannot be supported. Pantodon 'flight' is ballistic.

  13. The principal structure of male genital sclerites and muscles of bombycoid moths, with special reference to Anthelidae (Lepidoptera: Bombycoidea).

    PubMed

    Zwick, Andreas

    2009-03-01

    Male genital structures and muscles of bombycoid moths have repeatedly been misidentified in the literature. Furthermore, the genital structures of some bombycoid families, such as the poorly known Australo-New Guinean Anthelidae, have essentially remained unstudied. Based on comparative morphology, this study details the principal arrangements of male genital sclerites and muscles in all bombycoid families, with particular focus on basic structures and their modifications in Anthelidae. Emphasis is placed on the homology of and fusions between these structures and their function, providing a basis for the interpretation of modifications in future phylogenetic and taxonomic studies. This includes the unique fusion of gnathos and valvae in several bombycoid families, the arrangement and extent of the fused tegumen and vinculum, as well as the homology of the "transtilla". Further, a modification of the valve adductor muscle (the segment IX sternum to valva muscle, m4) widely regarded as a synapomorphy of Bombycoidea is demonstrated to be non-existent, as is the presumed presence of the valve abductor muscle (the segment IX tergum to valva muscle, m2) in Saturniidae.

  14. Simulations of foot stability during gait characteristic of ankle dorsiflexor weakness in the elderly.

    PubMed

    Gefen, A

    2001-12-01

    Falls are common among the elderly and often cause injuries. They most frequently occut during walking and are associated with the chronic deterioration in neuromuscular and sensory systems, as well as with ankle dorsiflexor muscular weakness and lowered endurance of these muscles to fatigue. In the present study, a three-dimensional (3-D) finite element model of the structure of the foot was utilized to determine the effects of ankle dorsiflexor muscle weakness on the structural stability of the foot and, consequently, on the risk of falls during gait. The medial-lateral tendency of instability of the foot during gait in such conditions of weakness was analyzed by means of this model to identify the most important muscles used in controlling foot stability in affected individuals. The values of the eccentricity of the center of pressure under the heel during foot placement were used to indicate the degree of foot stability. The computational analysis indicated that it is the tibialis anterior muscle's weakness that dramatically decreases foot stability. Clinical investigation is now needed to correlate the significance of tibialis anterior muscle weakness with other known risk factors affecting the tendency to falls among the elderly, e.g., deterioration of sensory abilities. Rehabilitation practitioners and physical therapists may apply the present analytic approach to evaluate the stability of a foot before treatment and compare the predicted with the actual therapeutic results in terms of optimization of foot-ground pressure.

  15. A comparison of respiratory and peripheral muscle strength, functional exercise capacity, activities of daily living and physical fitness in patients with cystic fibrosis and healthy subjects.

    PubMed

    Arikan, Hulya; Yatar, İlker; Calik-Kutukcu, Ebru; Aribas, Zeynep; Saglam, Melda; Vardar-Yagli, Naciye; Savci, Sema; Inal-Ince, Deniz; Ozcelik, Ugur; Kiper, Nural

    2015-01-01

    There are limited reports that compare muscle strength, functional exercise capacity, activities of daily living (ADL) and parameters of physical fitness of cystic fibrosis (CF) patients with healthy peers in the literature. The purpose of this study was to assess and compare respiratory and peripheral muscle strength, functional exercise capacity, ADL and physical fitness in patients with CF and healthy subjects. Nineteen patients with CF (mean forced expiratory volume in one second-FEV1: 86.56±18.36%) and 20 healthy subjects were included in this study. Respiratory (maximal inspiratory pressure-MIP and maximal expiratory pressure-MEP) and peripheral muscle strength (quadriceps, shoulder abductors and hand grip strength) were evaluated. Functional exercise capacity was determined with 6min walk test (6MWT). ADL was assessed with Glittre ADL test and physical fitness was assessed with Munich fitness test (MFT). There were not any statistically significant difference in MIP, %MIP, MEP and %MEP values between two groups (p>0.05). %Peripheral muscle strength (% quadriceps and shoulder abductors strength), 6MWT distance and %6MWT distance were significantly lower in patients with CF than those of healthy subjects (p<0.05). Glittre ADL-test time was significantly longer in patients with CF than healthy subjects (p<0.05). According to Munich fitness test, the number of bouncing a ball, hanging score, distance of standing vertical jumping and standing vertical jumping score were significantly lower in patients with CF than those of healthy subjects (p<0.05). Peripheral muscle strength, functional exercise capacity, ADL performance and speed, coordination, endurance and power components of physical fitness are adversely affected in mild-severe patients with CF compared to healthy peers. Evaluations must be done in comprehensive manner in patients with CF with all stages.

  16. Weak Energy: Form and Function

    NASA Astrophysics Data System (ADS)

    Parks, Allen D.

    The equation of motion for a time-dependent weak value of a quantum mechanical observable contains a complex valued energy factor—the weak energy of evolution. This quantity is defined by the dynamics of the pre-selected and post-selected states which specify the observable's weak value. It is shown that this energy: (i) is manifested as dynamical and geometric phases that govern the evolution of the weak value during the measurement process; (ii) satisfies the Euler-Lagrange equations when expressed in terms of Pancharatnam (P) phase and Fubini-Study (FS) metric distance; (iii) provides for a PFS stationary action principle for quantum state evolution; (iv) time translates correlation amplitudes; (v) generalizes the temporal persistence of state normalization; and (vi) obeys a time-energy uncertainty relation. A similar complex valued quantity—the pointed weak energy of an evolving quantum state—is also defined and several of its properties in PFS coordinates are discussed. It is shown that the imaginary part of the pointed weak energy governs the state's survival probability and its real part is—to within a sign—the Mukunda-Simon geometric phase for arbitrary evolutions or the Aharonov-Anandan (AA) geometric phase for cyclic evolutions. Pointed weak energy gauge transformations and the PFS 1-form are defined and discussed and the relationship between the PFS 1-form and the AA connection 1-form is established. [Editors note: for a video of the talk given by Prof. Parks at the Aharonov-80 conference in 2012 at Chapman University, see http://quantum.chapman.edu/talk-25.

  17. Stepping before standing: hip muscle function in stepping and standing balance after stroke

    PubMed Central

    Kirker, S; Simpson, D; Jenner, J; Wing, A

    2000-01-01

    OBJECTIVE—To compare the pattern of pelvic girdle muscle activation in normal subjects and hemiparetic patients while stepping and maintaining standing balance.
DESIGN—Group comparison.
METHOD—Seventeen patients who had regained the ability to walk after a single hemiparetic stroke were studied together with 16 normal controls. Median interval between stroke and testing was 17 months. Amplitude and onset latency of surface EMG activity in hip abductors and adductors were recorded in response to sideways pushes in either direction while standing. Similar recordings were made in the same subjects during gait initiation and a single stride.
RESULTS—In the standing balance task, normal subjects resisted a sideways push to the left with the left gluteus medius (74 ms) and with the right adductor (111 ms), and vice versa. In hemiparetic patients, the amplitude of activity was reduced in the hemiparetic muscles, the onset latencies of which were delayed (gluteus medius 96 ms, adductor 144 ms). Contralateral, non-paretic, adductor activity was increased after a push towards the hemiparetic side of patients with stroke and the latency was normal (110 ms). During self initiated sideways weight shifts at gait initiation, hemiplegic muscle activation was impaired. By contrast, the pattern and peak amplitude of hip muscle activation in stepping was normal in both hemiparetic and non-hemiparetic muscles of the subjects with stroke.
CONCLUSIONS—In ambulant patients with stroke, a normal pattern of activation of hemiparetic muscles is seen in stepping whereas the response of these muscles to a perturbation while standing remains grossly impaired and is compensated by increased activity of the contralateral muscles. This suggests that hemiparetic patients should be able to step before regaining standing balance.

 PMID:10727481

  18. Quantification of Electromyographic Activity During REM Sleep in Multiple Muscles in REM Sleep Behavior Disorder

    PubMed Central

    Frauscher, Birgit; Iranzo, Alex; Högl, Birgit; Casanova-Molla, Jordi; Salamero, Manel; Gschliesser, Viola; Tolosa, Eduardo; Poewe, Werner; Santamaria, Joan

    2008-01-01

    Study Objectives: The aim of our study was to determine which muscle or combination of muscles (either axial or limb muscles, lower or upper limb muscles, or proximal or distal limb muscles) provides the highest rates of rapid eye movement (REM) sleep phasic electromyographic (EMG) activity seen in patients with REM sleep behavior disorder (RBD). Setting: Two university hospital sleep disorders centers. Participants: Seventeen patients with idiopathic RBD (n = 8) and RBD secondary to Parkinson disease (n = 9). Interventions: Not applicable. Measurements and Results: Patients underwent polysomnography, including EMG recording of 13 different muscles. Phasic EMG activity in REM sleep was quantified for each muscle separately. A mean of 1459.6 ± 613.8 three-second REM sleep mini-epochs were scored per patient. Mean percentages of phasic EMG activity were mentalis (42 ± 19), flexor digitorum superficialis (29 ± 13), extensor digitorum brevis (23 ± 12), abductor pollicis brevis (22 ± 11), sternocleidomastoid (22 ± 12), deltoid (19 ± 11), biceps brachii (19 ± 11), gastrocnemius (18 ± 9), tibialis anterior (right, 17 ± 12; left, 16 ± 10), rectus femoris (left, 11 ± 6; right, 9 ± 6), and thoraco-lumbar paraspinal muscles (6 ± 5). The mentalis muscle provided significantly higher rates of excessive phasic EMG activity than all other muscles but only detected 55% of all the mini-epochs with phasic EMG activity. Simultaneous recording of the mentalis, flexor digitorum superficialis, and extensor digitorum brevis muscles detected 82% of all mini-epochs containing phasic EMG activity. This combination provided higher rates of EMG activity than any other 3-muscle combination. Excessive phasic EMG activity was more frequent in distal than in proximal muscles, both in upper and lower limbs. Conclusion: Simultaneous recording of the mentalis, flexor digitorum superficialis, and extensor digitorum brevis muscles provided the highest rates of REM sleep phasic EMG

  19. Immune Mediated Necrotizing Myopathy: a Cause of Isolated Myopathy of Neck Extensor Muscle

    PubMed Central

    Sehgal, Rahul; Medina-Flores, Rafael; Yachoui, Ralph; Kenney, Charles V

    2016-01-01

    Immune mediated necrotizing myopathy (IMNM) is a unique form of myositis that is characterized by distinct muscle biopsy features including abundant myofiber necrosis, degeneration, and regeneration with only minimal, if any, inflammation on muscle biopsy. IMNM is clinically similar to idiopathic inflammatory myopathy (IIM); hence, muscle biopsy is essential to diagnose IMNM. Herein we describe a case of neck extensor weakness due to necrotizing myopathy. Isolated weakness of the neck extensor muscles is uncommon in IIM and IMNM. This case describes the diagnostic work-up, treatments utilized, and 2 year follow-up course without involvement of other muscle groups and without progression of neck extensor muscle weakness. Advanced imaging using magnetic resonance imaging (MRI) facilitated the diagnosis by identifying the affected muscles and site for muscle biopsy. PMID:27573534

  20. Preoperative gluteus medius muscle atrophy as a predictor of walking ability after total hip arthroplasty

    PubMed Central

    NANKAKU, Manabu; TSUBOYAMA, Tadao; AOYAMA, Tomoki; KURODA, Yutaka; IKEGUCHI, Ryosuke; MATSUDA, Shuichi

    2016-01-01

    Purpose: To elucidate the relation between certain preoperative physical parameters and walking with a limp after total hip arthroplasty (THA) and determine whether it is possible to predict the walking ability of patients 6 months after THA. Methods: The subjects of this study comprised 74 female patients who had undergone unilateral THA. Before surgery, the hip abductor and knee extensor strengths were measured, the cross-sectional areas (CSAs) of the gluteus medius and rectus abdominis muscles were measured, and the Timed Up and Go test was conducted. The patients were then divided into two groups according to gait observation results 6 months postoperatively: walking without a limp (n=37) and walking with a limp (n=37). Results: The discriminating criteria between the two groups were age (61 years), CSA of the gluteus medius muscle (2000 mm2), and CSA of the rectus abdominis muscle (340 mm2). In the multiple logistic regression analysis, the gluteus medius muscle was the only significant predictor of limping after THA (β=1.64, R2=0.19, p<0.01). Conclusions: The results of the present study suggest that preoperative atrophy of the gluteus medius is an useful indicator for predicting walking with a limp 6 months postoperatively. PMID:28289576

  1. Regenerative function of immune system: Modulation of muscle stem cells.

    PubMed

    Saini, Jasdeep; McPhee, Jamie S; Al-Dabbagh, Sarah; Stewart, Claire E; Al-Shanti, Nasser

    2016-05-01

    Ageing is characterised by progressive deterioration of physiological systems and the loss of skeletal muscle mass is one of the most recognisable, leading to muscle weakness and mobility impairments. This review highlights interactions between the immune system and skeletal muscle stem cells (widely termed satellite cells or myoblasts) to influence satellite cell behaviour during muscle regeneration after injury, and outlines deficits associated with ageing. Resident neutrophils and macrophages in skeletal muscle become activated when muscle fibres are damaged via stimuli (e.g. contusions, strains, avulsions, hyperextensions, ruptures) and release high concentrations of cytokines, chemokines and growth factors into the microenvironment. These localised responses serve to attract additional immune cells which can reach in excess of 1×10(5) immune cell/mm(3) of skeletal muscle in order to orchestrate the repair process. T-cells have a delayed response, reaching peak activation roughly 4 days after the initial damage. The cytokines and growth factors released by activated T-cells play a key role in muscle satellite cell proliferation and migration, although the precise mechanisms of these interactions remain unclear. T-cells in older people display limited ability to activate satellite cell proliferation and migration which is likely to contribute to insufficient muscle repair and, consequently, muscle wasting and weakness. If the factors released by T-cells to activate satellite cells can be identified, it may be possible to develop therapeutic agents to enhance muscle regeneration and reduce the impact of muscle wasting during ageing and disease.

  2. Warping the Weak Gravity Conjecture

    NASA Astrophysics Data System (ADS)

    Kooner, Karta; Parameswaran, Susha; Zavala, Ivonne

    2016-08-01

    The Weak Gravity Conjecture, if valid, rules out simple models of Natural Inflation by restricting their axion decay constant to be sub-Planckian. We revisit stringy attempts to realise Natural Inflation, with a single open string axionic inflaton from a probe D-brane in a warped throat. We show that warped geometries can allow the requisite super-Planckian axion decay constant to be achieved, within the supergravity approximation and consistently with the Weak Gravity Conjecture. Preliminary estimates of the brane backreaction suggest that the probe approximation may be under control. However, there is a tension between large axion decay constant and high string scale, where the requisite high string scale is difficult to achieve in all attempts to realise large field inflation using perturbative string theory. We comment on the Generalized Weak Gravity Conjecture in the light of our results.

  3. Weak values in continuous weak measurements of qubits

    NASA Astrophysics Data System (ADS)

    Qin, Lupei; Liang, Pengfei; Li, Xin-Qi

    2015-07-01

    For continuous weak measurements of qubits, we obtain exact expressions for weak values (WVs) from the postselection restricted average of measurement outputs, by using both the quantum-trajectory equation (QTE) and the quantum Bayesian approach. The former is applicable to short-time weak measurement, while the latter can relax the measurement strength to finite. We find that even in the "very" weak limit the result can be essentially different from the one originally proposed by Aharonov, Albert, and Vaidman (AAV), in the sense that our result incorporates nonperturbative correction which could be important when the AAV WV is large. Within the Bayesian framework, we obtain also elegant expressions for finite measurement strength and find that the amplifier's noise in quantum measurement has no effect on the WVs. In particular, we obtain very useful results for homodyne measurement in a circuit-QED system, which allows for measuring the real and imaginary parts of the AAV WV by simply tuning the phase of the local oscillator. This advantage can be exploited as an efficient state-tomography technique.

  4. Weak localization and weak antilocalization in doped germanium epilayers

    NASA Astrophysics Data System (ADS)

    Newton, P. J.; Mansell, R.; Holmes, S. N.; Myronov, M.; Barnes, C. H. W.

    2017-02-01

    The magnetoresistance of 50 nm thick epilayers of doped germanium is measured at a range of temperatures down to 1.6 K. Both n- and p-type devices show quantum corrections to the conductivity in an applied magnetic field, with n-type devices displaying weak localization and p-type devices showing weak antilocalization. From fits to these data using the Hikami-Larkin-Nagaoka model, the phase coherence length of each device is extracted, as well as the spin diffusion length of the p-type device. We obtain phase coherence lengths as large as 325 nm in the highly doped n-type device, presenting possible applications in quantum technologies. The decay of the phase coherence length with temperature is found to obey the same power law of lϕ ∝ Tc, where c = -0.68 ± 0.03, for each device, in spite of the clear differences in the nature of the conduction. In the p-type device, the measured spin diffusion length does not change over the range of temperatures for which weak antilocalization can be observed. The presence of a spin-orbit interaction manifested as weak antilocalization in the p-type epilayer suggests that these structures could be developed for use in spintronic devices such as the spin-FET, where significant spin lifetimes would be important for efficient device operation.

  5. Cosmology and the weak interaction

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1989-01-01

    The weak interaction plays a critical role in modern Big Bang cosmology. Two of its most publicized comological connections are emphasized: big bang nucleosynthesis and dark matter. The first of these is connected to the cosmological prediction of neutrine flavors, N(sub nu) is approximately 3 which in now being confirmed. The second is interrelated to the whole problem of galacty and structure formation in the universe. The role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure is demonstrated.

  6. Cosmology and the weak interaction

    SciTech Connect

    Schramm, D.N. ):)

    1989-12-01

    The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

  7. Muscle strain (image)

    MedlinePlus

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  8. Anisotropic weak localization of light.

    PubMed

    Sapienza, Riccardo; Mujumdar, Sushil; Cheung, Cecil; Yodh, A G; Wiersma, Diederik

    2004-01-23

    We have observed angular anisotropy in weak localization of light from highly scattering, orientationally ordered, nematic liquid crystals. This demonstration of angular anisotropy in a multiple-scattering interference phenomenon was facilitated by a light scattering instrument with extraordinary angular resolution. The measured anisotropies were consistent with a simple model of coherent backscattering generalized for propagation-direction dependent mean free paths.

  9. N-{Delta} weak transition

    SciTech Connect

    Graczyk, Krzysztof M.

    2011-11-23

    A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-{Delta}(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.

  10. Theory of weak hypernuclear decay

    SciTech Connect

    Dubach, J.F.; Feldman, G.B.; Holstein, B.R. |; de la Torre, L.

    1996-07-01

    The weak nomesonic decay of {Lambda}-hypernuclei is studied in the context of a one-meson-exchange model. Predictions are made for the decay rate, the {ital p}/{ital n} stimulation ratio and the asymmetry in polarized hypernuclear decay. Copyright {copyright} 1996 Academic Press, Inc.

  11. Weak localization of seismic waves.

    PubMed

    Larose, E; Margerin, L; Van Tiggelen, B A; Campillo, M

    2004-07-23

    We report the observation of weak localization of seismic waves in a natural environment. It emerges as a doubling of the seismic energy around the source within a spot of the width of a wavelength, which is several tens of meters in our case. The characteristic time for its onset is the scattering mean-free time that quantifies the internal heterogeneity.

  12. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

  13. Electrically controllable artificial PAN muscles

    NASA Astrophysics Data System (ADS)

    Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

    1996-02-01

    Artificial muscles made with polyacrylonitrile (PAN) fibers are traditionally activated in electrolytic solution by changing the pH of the solution by the addition of acids and/or bases. This usually consumes a considerable amount of weak acids or bases. Furthermore, the synthetic muscle (PAN) itself has to be impregnated with an acid or a base and must have an appropriate enclosure or provision for waste collection after actuation. This work introduces a method by which the PAN muscle may be elongated or contracted in an electric field. We believe this is the first time that this has been achieved with PAN fibers as artificial muscles. In this new development the PAN muscle is first put in close contact with one of the two platinum wires (electrodes) immersed in an aqueous solution of sodium chloride. Applying an electric voltage between the two wires changes the local acidity of the solution in the regions close to the platinum wires. This is because of the ionization of sodium chloride molecules and the accumulation of Na+ and Cl- ions at the negative and positive electrode sites, respectively. This ion accumulation, in turn, is accompanied by a sharp increase and decrease of the local acidity in regions close to either of the platinum wires, respectively. An artificial muscle, in close contact with the platinum wire, because of the change in the local acidity will contract or expand depending on the polarity of the electric field. This scheme allows the experimenter to use a fixed flexible container of an electrolytic solution whose local pH can be modulated by an imposed electric field while the produced ions are basically trapped to stay in the neighborhood of a given electrode. This method of artificial muscle activation has several advantages. First, the need to use a large quantity of acidic or alkaline solutions is eliminated. Second, the use of a compact PAN muscular system is facilitated for applications in active musculoskeletal structures. Third, the

  14. Differential contributions of vision, touch and muscle proprioception to the coding of hand movements.

    PubMed

    Blanchard, Caroline; Roll, Régine; Roll, Jean-Pierre; Kavounoudias, Anne

    2013-01-01

    To further elucidate the mechanisms underlying multisensory integration, this study examines the controversial issue of whether congruent inputs from three different sensory sources can enhance the perception of hand movement. Illusory sensations of clockwise rotations of the right hand were induced by either separately or simultaneously stimulating visual, tactile and muscle proprioceptive channels at various intensity levels. For this purpose, mechanical vibrations were applied to the pollicis longus muscle group in the subjects' wrists, and a textured disk was rotated under the palmar skin of the subjects' right hands while a background visual scene was projected onto the rotating disk. The elicited kinaesthetic illusions were copied by the subjects in real time and the EMG activity in the adductor and abductor wrist muscles was recorded. The results show that the velocity of the perceived movements and the amplitude of the corresponding motor responses were modulated by the nature and intensity of the stimulation. Combining two sensory modalities resulted in faster movement illusions, except for the case of visuo-tactile co-stimulation. When a third sensory input was added to the bimodal combinations, the perceptual responses increased only when a muscle proprioceptive stimulation was added to a visuo-tactile combination. Otherwise, trisensory stimulation did not override bimodal conditions that already included a muscle proprioceptive stimulation. We confirmed that vision or touch alone can encode the kinematic parameters of hand movement, as is known for muscle proprioception. When these three sensory modalities are available, they contribute unequally to kinaesthesia. In addition to muscle proprioception, the complementary kinaesthetic content of visual or tactile inputs may optimize the velocity estimation of an on-going movement, whereas the redundant kinaesthetic content of the visual and tactile inputs may rather enhance the latency of the perception.

  15. Isokinetic evaluation of trunk muscles.

    PubMed

    Langrana, N A; Lee, C K

    1984-03-01

    The purpose of this study is to identify those individuals at risk who have weak trunk muscles and are prone to back pain. The overall thrust of this research is to develop a quantitative method to assess dynamic strength of the trunk muscles. Two unique isokinetic strength testing units in sitting and standing postures have been designed. Three groups of volunteers were tested at different times and places. Quantitative measurements of the maximum strength, fatigue behavior of the abdominal and paraspinal muscles, maximum strength in different age groups and the role of the iliopsoas muscle have been performed. The study shows that women have lower maximum strength but equal or better fatigue endurance than men. There is a significant change in maximum strength with age. The maximum abdominal strength change with age showed a bimodal distribution. The iliopsoas muscle approximately doubled the maximum back strength in flexion. The test in the sitting posture was tolerated better than the test in the standing posture. Isokinetic back strength testing in the sitting posture was found to be effective and safe.

  16. Respiratory dysfunction in ventilated patients: can inspiratory muscle training help?

    PubMed

    Bissett, B; Leditschke, I A; Paratz, J D; Boots, R J

    2012-03-01

    Respiratory muscle dysfunction is associated with prolonged and difficult weaning from mechanical ventilation. This dysfunction in ventilator-dependent patients is multifactorial: there is evidence that inspiratory muscle weakness is partially explained by disuse atrophy secondary to ventilation, and positive end-expiratory pressure can further reduce muscle strength by negatively shifting the length-tension curve of the diaphragm. Polyneuropathy is also likely to contribute to apparent muscle weakness in critically ill patients, and nutritional and pharmaceutical effects may further compound muscle weakness. Moreover, psychological influences, including anxiety, may contribute to difficulty in weaning. There is recent evidence that inspiratory muscle training is safe and feasible in selected ventilator-dependent patients, and that this training can reduce the weaning period and improve overall weaning success rates. Extrapolating from evidence in sports medicine, as well as the known effects of inspiratory muscle training in chronic lung disease, a theoretical model is proposed to describe how inspiratory muscle training enhances weaning and recovery from mechanical ventilation. Possible mechanisms include increased protein synthesis (both Type 1 and Type 2 muscle fibres), enhanced limb perfusion via dampening of a sympathetically-mediated metaboreflex, reduced lactate levels and modulation of the perception of exertion, resulting in less dyspnoea and enhanced exercise capacity.

  17. Weak values and weak coupling maximizing the output of weak measurements

    SciTech Connect

    Di Lorenzo, Antonio

    2014-06-15

    In a weak measurement, the average output 〈o〉 of a probe that measures an observable A{sup -hat} of a quantum system undergoing both a preparation in a state ρ{sub i} and a postselection in a state E{sub f} is, to a good approximation, a function of the weak value A{sub w}=Tr[E{sub f}A{sup -hat} ρ{sub i}]/Tr[E{sub f}ρ{sub i}], a complex number. For a fixed coupling λ, when the overlap Tr[E{sub f}ρ{sub i}] is very small, A{sub w} diverges, but 〈o〉 stays finite, often tending to zero for symmetry reasons. This paper answers the questions: what is the weak value that maximizes the output for a fixed coupling? What is the coupling that maximizes the output for a fixed weak value? We derive equations for the optimal values of A{sub w} and λ, and provide the solutions. The results are independent of the dimensionality of the system, and they apply to a probe having a Hilbert space of arbitrary dimension. Using the Schrödinger–Robertson uncertainty relation, we demonstrate that, in an important case, the amplification 〈o〉 cannot exceed the initial uncertainty σ{sub o} in the observable o{sup -hat}, we provide an upper limit for the more general case, and a strategy to obtain 〈o〉≫σ{sub o}. - Highlights: •We have provided a general framework to find the extremal values of a weak measurement. •We have derived the location of the extremal values in terms of preparation and postselection. •We have devised a maximization strategy going beyond the limit of the Schrödinger–Robertson relation.

  18. Abdominal muscle and quadriceps strength in chronic obstructive pulmonary disease

    PubMed Central

    Man, W; Hopkinson, N; Harraf, F; Nikoletou, D; Polkey, M; Moxham, J

    2005-01-01

    Background: Quadriceps muscle weakness is common in chronic obstructive pulmonary disease (COPD) but is not observed in a small hand muscle (adductor pollicis). Although this could be explained by reduced activity in the quadriceps, the observation could also be explained by anatomical location of the muscle or fibre type composition. However, the abdominal muscles are of a similar anatomical and fibre type distribution to the quadriceps, although they remain active in COPD. Cough gastric pressure is a recently described technique that assesses abdominal muscle (and hence expiratory muscle) strength more accurately than traditional techniques. A study was undertaken to test the hypothesis that more severe weakness exists in the quadriceps than in the abdominal muscles of patients with COPD compared with healthy elderly controls. Methods: Maximum cough gastric pressure and quadriceps isometric strength were measured in 43 patients with stable COPD and 25 healthy elderly volunteers matched for anthropometric variables. Results: Despite a significant reduction in mean quadriceps strength (29.9 kg v 41.2 kg; 95% CI –17.9 to –4.6; p = 0.001), cough gastric pressure was preserved in patients with COPD (227.3 cm H2O v 204.8 cm H2O; 95% CI –5.4 to 50.6; p = 0.11). Conclusions: Abdominal muscle strength is preserved in stable COPD outpatients in the presence of quadriceps weakness. This suggests that anatomical location and fibre type cannot explain quadriceps weakness in COPD. By inference, we conclude that disuse and consequent deconditioning are important factors in the development of quadriceps muscle weakness in COPD patients, or that activity protects the abdominal muscles from possible systemic myopathic processes. PMID:15923239

  19. Tomography and weak lensing statistics

    SciTech Connect

    Munshi, Dipak; Coles, Peter; Kilbinger, Martin E-mail: peter.coles@astro.cf.ac.uk

    2014-04-01

    We provide generic predictions for the lower order cumulants of weak lensing maps, and their correlators for tomographic bins as well as in three dimensions (3D). Using small-angle approximation, we derive the corresponding one- and two-point probability distribution function for the tomographic maps from different bins and for 3D convergence maps. The modelling of weak lensing statistics is obtained by adopting a detailed prescription for the underlying density contrast that involves hierarchal ansatz and lognormal distribution. We study the dependence of our results on cosmological parameters and source distributions corresponding to the realistic surveys such as LSST and DES. We briefly outline how photometric redshift information can be incorporated in our results. We also show how topological properties of convergence maps can be quantified using our results.

  20. Cancer cachexia decreases specific force and accelerates fatigue in limb muscle

    SciTech Connect

    Roberts, B.M.; Frye, G.S.; Ahn, B.; Ferreira, L.F.; Judge, A.R.

    2013-06-07

    Highlights: •C-26 cancer cachexia causes a significant decrease in limb muscle absolute force. •C-26 cancer cachexia causes a significant decrease in limb muscle specific force. •C-26 cancer cachexia decreases fatigue resistance in the soleus muscle. •C-26 cancer cachexia prolongs time to peak twitch tension in limb muscle. •C-26 cancer cachexia prolongs one half twitch relaxation time in limb muscle. -- Abstract: Cancer cachexia is a complex metabolic syndrome that is characterized by the loss of skeletal muscle mass and weakness, which compromises physical function, reduces quality of life, and ultimately can lead to mortality. Experimental models of cancer cachexia have recapitulated this skeletal muscle atrophy and consequent decline in muscle force generating capacity. However, more recently, we provided evidence that during severe cancer cachexia muscle weakness in the diaphragm muscle cannot be entirely accounted for by the muscle atrophy. This indicates that muscle weakness is not just a consequence of muscle atrophy but that there is also significant contractile dysfunction. The current study aimed to determine whether contractile dysfunction is also present in limb muscles during severe Colon-26 (C26) carcinoma cachexia by studying the glycolytic extensor digitorum longus (EDL) muscle and the oxidative soleus muscle, which has an activity pattern that more closely resembles the diaphragm. Severe C-26 cancer cachexia caused significant muscle fiber atrophy and a reduction in maximum absolute force in both the EDL and soleus muscles. However, normalization to muscle cross sectional area further demonstrated a 13% decrease in maximum isometric specific force in the EDL and an even greater decrease (17%) in maximum isometric specific force in the soleus. Time to peak tension and half relaxation time were also significantly slowed in both the EDL and the solei from C-26 mice compared to controls. Since, in addition to postural control, the oxidative

  1. Role of reactive oxygen species in the defective regeneration seen in aging muscle.

    PubMed

    Vasilaki, Aphrodite; Jackson, Malcolm J

    2013-12-01

    The ability of muscles to regenerate successfully following damage diminishes with age and this appears to be a major contributor to the development of muscle weakness and physical frailty. Successful muscle regeneration is dependent on appropriate reinnervation of regenerating muscle. Age-related changes in the interactions between nerve and muscle are poorly understood but may play a major role in the defective regeneration. During aging there is defective redox homeostasis and an accumulation of oxidative damage in nerve and muscle that may contribute to defective regeneration. The aim of this review is to summarise the evidence that abnormal reactive oxygen species (ROS) generation in nerve and/or muscle may be responsible for the defective regeneration that contributes to the degeneration of skeletal muscle observed during aging. Identifying the importance of ROS generation in skeletal muscle during aging could have fundamental implications for interventions to prevent muscle degeneration and treatments to reverse the age-related decline in muscle mass and function.

  2. Correlation of single-breath count test and neck flexor muscle strength with spirometry in myasthenia gravis

    PubMed Central

    Elsheikh, Bakri; Arnold, W. David; Gharibshahi, Shahram; Reynolds, Jerold; Freimer, Miriam; Kissel, John T.

    2015-01-01

    Introduction Although formal spirometry is the gold standard for monitoring respiratory function in patients with myasthenia gravis (MG), such testing is often delayed or unavailable. There is a need for a simple bedside test that can accurately measure respiratory function. Method We conducted a prospective, cross-sectional, single-blind study in adults with acetylcholine receptor antibody positive MG. Participants performed the single breath count test (SBCT) and underwent manual muscle strength testing, while a respiratory therapist performed spirometry blinded to SBCT and strength results. Results Thirty-one patients, aged 57 ±19 years participated. SBCT showed significant correlations with forced vital capacity (FVC), negative inspiratory force (NIF), and neck flexor strength (P<0.01). FVC showed significant correlation with neck flexor strength (P=0.02) but no correlation with shoulder abductor strength. Discussion These data suggest that the SBCT and neck flexor strength testing are valuable tools for bedside assessment of respiratory function in MG patients. PMID:26437790

  3. Quadriceps muscle strength in scoliosis.

    PubMed

    Swallow, E B; Barreiro, E; Gosker, H; Sathyapala, S A; Sanchez, F; Hopkinson, N S; Moxham, J; Schols, A; Gea, J; Polkey, M I

    2009-12-01

    Quadriceps muscle weakness is an important component of chronic obstructive pulmonary disease (COPD). We hypothesised that quadriceps weakness would also be a feature of restrictive lung disease due to scoliosis. We studied 10 patients with severe scoliosis (median (interquartile range (IQR)) forced expiratory volume in 1 s (FEV(1))() 35.3 (11)% predicted), 10 patients with severe COPD (FEV(1) 26.5 (9.0)% pred) and 10 healthy age-matched adults. We measured quadriceps strength, exercise capacity and analysed quadriceps muscle biopsies for myosin heavy-chain (MyHC) isoform expression and the presence of oxidative stress. Both groups exhibited quadriceps weakness with median (IQR) maximal voluntary contraction force being 46.0 (17.0) kg, 21.5 (21.0) kg and 31.5 (11.0) kg, respectively (p = 0.02 and 0.04, respectively, for each patient group against controls). Oxidative stress was significantly greater in the quadriceps of both restrictive and COPD patients. The scoliosis patients exhibited a decrease in the proportion of MyHC type I compared with controls; median (IQR) 35.3 (18.5)% compared with 47.7 (9.3)%, p = 0.028. The scoliosis patients also showed an increase in MyHC IIx (26.3 (15.5)% compared with 11.3 (13.0)%, p = 0.01. Quadriceps weakness is a feature of severe scoliosis; the similarities between patients with scoliosis and patients with COPD suggest a common aetiology to quadriceps weakness in both conditions.

  4. Quantifying shoulder rotation weakness in patients with shoulder impingement.

    PubMed

    Tyler, Timothy F; Nahow, Rachael C; Nicholas, Stephen J; McHugh, Malachy P

    2005-01-01

    The purpose of this study was to determine whether strength deficits could be detected in individuals with and without shoulder impingement, all of whom had normal shoulder strength bilaterally according to grading of manual muscle testing. Strength of the internal rotators and external rotators was tested isokinetically at 60 degrees /s and 180 degrees /s, as well as manually with a handheld dynamometer (HHD) in 17 patients and 22 control subjects. Testing was performed with the shoulder positioned in the scapular plane and in 90 degrees of shoulder abduction with 90 degrees of elbow flexion (90-90). The peak torque was determined for each movement. The strength deficit between the involved and uninvolved arms (patients) and the dominant and nondominant arms (control subjects) was calculated for each subject. Comparisons were made for the scapular-plane and 90-90 positions between isokinetic and HHD testing. Despite a normal muscle grade, patients had marked weakness (28% deficit, P < .01) in external rotators at the 90-90 position tested with the HHD. In contrast, external rotator weakness was not evident with isokinetic testing at the 90-90 position (60 degrees /s and 180 degrees /s, 0% deficit, P = .99). In control subjects, greater internal rotator strength in the dominant compared with the nondominant arm was evident with the HHD at the 90-90 position (11%, P < .01) and in the scapular plane (7%, P < .05). Using an HHD while performing manual muscle testing can quantify shoulder strength deficits that may not be apparent with isokinetic testing. By using an HHD during shoulder testing, clinicians can identify weakness that may have been presumed normal.

  5. Shock wave over hand muscles: a neurophysiological study on peripheral conduction nerves in normal subjects

    PubMed Central

    Manganotti, Paolo; Amelio, Ernesto; Guerra, Claudio

    2012-01-01

    Summary Background and purpose: shock waves are defined as a sequence of single sonic pulses largely used in the treatment of bone and tendon diseases and recently on muscular hypertonia in stroke patients. Our purpose is to investigate the short and long term effect of extra-corporeal shock wave therapy (ESWT) on the peripheral nerve conduction and central conductions from the treated muscles in normal human subjects in order to define safety criteria. Methods: we studied 10 patients normal subjects. Motor and sensory nerve conduction velocity and F response from right ipothenar eminence (abductor digiti minimi) of the hand was recorded. Furthermore MEP latency and amplitude and central conduction from the same muscles by transcranial magnetic stimulation was evaluated. In all subjects each neurophysiological measures were monitored before, immediately after, 15 minutes and after 30 minutes from the active ESWT treatment (1600 shots with an energy applied of 0.030 mj/mm2). Results: no significant short or long term changes were noted in sensory and motor peripheral nerve conduction and in central motor conduction in all the subjects evaluated after ESWT. Conclusions: the ESWT has no effect on sensory and motor peripheral nerve conduction and in central motor conduction. The ESWT using low level of energy represent a safety method for treating the muscles in human subjects without involvement of motor or sensory nervous trunks. Different mechanisms of action of ESWT are discussed. PMID:23738282

  6. The relationship between hamstring length and gluteal muscle strength in individuals with sacroiliac joint dysfunction

    PubMed Central

    Massoud Arab, Amir; Reza Nourbakhsh, Mohammad; Mohammadifar, Ali

    2011-01-01

    It has been suggested that tight hamstring muscle, due to its anatomical connections, could be a compensatory mechanism for providing sacroiliac (SI) joint stability in patients with gluteal muscle weakness and SIJ dysfunction. The purpose of this study was to determine the relationship between hamstring muscle length and gluteal muscle strength in subjects with sacroiliac joint dysfunction. A total of 159 subjects with and without low back pain (LBP) between the ages of 20 and 65 years participate in the study. Subjects were categorized into three groups: LBP without SIJ involvement (n = 53); back pain with SIJ dysfunction (n = 53); and no low back pain (n = 53). Hamstring muscle length and gluteal muscle strength were measured in all subjects. The number of individuals with gluteal weakness was significantly (P = 0.02) higher in subjects with SI joint dysfunction (66%) compared to those with LBP without SI joint dysfunctions (34%). In pooled data, there was no significant difference (P = 0.31) in hamstring muscle length between subjects with SI joint dysfunction and those with back pain without SI involvement. In subjects with SI joint dysfunction, however, those with gluteal muscle weakness had significantly (P = 0.02) shorter hamstring muscle length (mean = 158±11°) compared to individuals without gluteal weakness (mean = 165±10°). There was no statistically significant difference (P>0.05) in hamstring muscle length between individuals with and without gluteal muscle weakness in other groups. In conclusion, hamstring tightness in subjects with SI joint dysfunction could be related to gluteal muscle weakness. The slight difference in hamstring muscle length found in this study, although statistically significant, was not sufficient for making any definite conclusions. Further studies are needed to establish the role of hamstring muscle in SI joint stability. PMID:22294848

  7. The relationship between hamstring length and gluteal muscle strength in individuals with sacroiliac joint dysfunction.

    PubMed

    Massoud Arab, Amir; Reza Nourbakhsh, Mohammad; Mohammadifar, Ali

    2011-02-01

    It has been suggested that tight hamstring muscle, due to its anatomical connections, could be a compensatory mechanism for providing sacroiliac (SI) joint stability in patients with gluteal muscle weakness and SIJ dysfunction. The purpose of this study was to determine the relationship between hamstring muscle length and gluteal muscle strength in subjects with sacroiliac joint dysfunction. A total of 159 subjects with and without low back pain (LBP) between the ages of 20 and 65 years participate in the study. Subjects were categorized into three groups: LBP without SIJ involvement (n = 53); back pain with SIJ dysfunction (n = 53); and no low back pain (n = 53). Hamstring muscle length and gluteal muscle strength were measured in all subjects. The number of individuals with gluteal weakness was significantly (P = 0.02) higher in subjects with SI joint dysfunction (66%) compared to those with LBP without SI joint dysfunctions (34%). In pooled data, there was no significant difference (P = 0.31) in hamstring muscle length between subjects with SI joint dysfunction and those with back pain without SI involvement. In subjects with SI joint dysfunction, however, those with gluteal muscle weakness had significantly (P = 0.02) shorter hamstring muscle length (mean = 158±11°) compared to individuals without gluteal weakness (mean = 165±10°). There was no statistically significant difference (P>0.05) in hamstring muscle length between individuals with and without gluteal muscle weakness in other groups. In conclusion, hamstring tightness in subjects with SI joint dysfunction could be related to gluteal muscle weakness. The slight difference in hamstring muscle length found in this study, although statistically significant, was not sufficient for making any definite conclusions. Further studies are needed to establish the role of hamstring muscle in SI joint stability.

  8. Leg Weakness Caused by Bilateral Piriformis Syndrome: A Case Report

    PubMed Central

    Moon, Hee Bong; Kwon, Bum Sun; Park, Jin Woo; Ryu, Gi Hyeong; Lee, Ho Jun; Kim, Chang Jae

    2015-01-01

    Piriformis syndrome (PS) is an uncommon neuromuscular disorder caused by the piriformis muscle (PM) compressing the sciatic nerve (SN). The main symptom of PS is sciatica, which worsens with certain triggering conditions. Because the pathophysiology is poorly understood, there are no definite diagnostic and therapeutic choices for PS. This case report presents a young woman who mainly complained of bilateral leg weakness. Electromyography revealed bilateral sciatic neuropathy and magnetic resonance imaging confirmed structural lesions causing entrapment of the bilateral SNs. After a laborious diagnosis of bilateral PS, she underwent PM releasing surgery. Few PS cases present with bilateral symptoms and leg weakness. Therefore, in such cases, a high level of suspicion is necessary for accurate and prompt diagnosis and treatment. PMID:26798622

  9. Leg Weakness Caused by Bilateral Piriformis Syndrome: A Case Report.

    PubMed

    Moon, Hee Bong; Nam, Ki Yeun; Kwon, Bum Sun; Park, Jin Woo; Ryu, Gi Hyeong; Lee, Ho Jun; Kim, Chang Jae

    2015-12-01

    Piriformis syndrome (PS) is an uncommon neuromuscular disorder caused by the piriformis muscle (PM) compressing the sciatic nerve (SN). The main symptom of PS is sciatica, which worsens with certain triggering conditions. Because the pathophysiology is poorly understood, there are no definite diagnostic and therapeutic choices for PS. This case report presents a young woman who mainly complained of bilateral leg weakness. Electromyography revealed bilateral sciatic neuropathy and magnetic resonance imaging confirmed structural lesions causing entrapment of the bilateral SNs. After a laborious diagnosis of bilateral PS, she underwent PM releasing surgery. Few PS cases present with bilateral symptoms and leg weakness. Therefore, in such cases, a high level of suspicion is necessary for accurate and prompt diagnosis and treatment.

  10. Collagen VI deficiency reduces muscle pathology, but does not improve muscle function, in the γ-sarcoglycan-null mouse.

    PubMed

    de Greef, Jessica C; Hamlyn, Rebecca; Jensen, Braden S; O'Campo Landa, Raul; Levy, Jennifer R; Kobuke, Kazuhiro; Campbell, Kevin P

    2016-04-01

    Muscular dystrophy is characterized by progressive skeletal muscle weakness and dystrophic muscle exhibits degeneration and regeneration of muscle cells, inflammation and fibrosis. Skeletal muscle fibrosis is an excessive deposition of components of the extracellular matrix including an accumulation of Collagen VI. We hypothesized that a reduction of Collagen VI in a muscular dystrophy model that presents with fibrosis would result in reduced muscle pathology and improved muscle function. To test this hypothesis, we crossed γ-sarcoglycan-null mice, a model of limb-girdle muscular dystrophy type 2C, with a Col6a2-deficient mouse model. We found that the resulting γ-sarcoglycan-null/Col6a2Δex5 mice indeed exhibit reduced muscle pathology compared with γ-sarcoglycan-null mice. Specifically, fewer muscle fibers are degenerating, fiber size varies less, Evans blue dye uptake is reduced and serum creatine kinase levels are lower. Surprisingly, in spite of this reduction in muscle pathology, muscle function is not significantly improved. In fact, grip strength and maximum isometric tetanic force are even lower in γ-sarcoglycan-null/Col6a2Δex5 mice than in γ-sarcoglycan-null mice. In conclusion, our results reveal that Collagen VI-mediated fibrosis contributes to skeletal muscle pathology in γ-sarcoglycan-null mice. Importantly, however, our data also demonstrate that a reduction in skeletal muscle pathology does not necessarily lead to an improvement of skeletal muscle function, and this should be considered in future translational studies.

  11. Reverse split hand syndrome: Dissociated intrinsic hand muscle atrophy pattern in Hirayama disease/brachial monomelic amyotrophy.

    PubMed

    Singh, Ravinder-Jeet; Preethish-Kumar, Veeramani; Polavarapu, Kiran; Vengalil, Seena; Prasad, Chandrajit; Nalini, Atchayaram

    2017-02-01

    Preferential involvement of C7, C8, T1 level anterior horn cells is a typical feature in Hirayama disease/brachial monomelic amyotrophy (BMMA). There are no clinico-electrophysiological studies to substantiate the peculiar pattern of muscle involvement. Thirty subjects, 10 in each group of BMMA, amyotrophic lateral sclerosis (ALS) and age-matched normal healthy subjects underwent detailed clinical and electrophysiological testing. Results showed that the mean age at evaluation for BMMA and ALS patients was 25.8 ± 3.8 and 51.8 ± 9.5 years, respectively; illness duration was 8.1 ± 5.7 years and 11.14 ± 2.85 months, respectively. Clinically, all BMMA patients had reverse of split hand (RSH) syndrome [abductor digiti minimi (ADM) affected more than abductor pollicis brevis (APB)], while 7/10 ALS patients had classical split hand syndrome (APB affected more than ADM). In BMMA, the compound muscle action potential (CMAP) of APB was preserved but reduced/absent in ADM compared to the ALS group which demonstrated reverse findings. APB/ADM ratio was >0.8 in the BMMA group (>1.4 in 80%), around 1.0 in normal controls (none had >1.4) and <0.8 in ALS (70% having values <0.6). In conclusion, RSH syndrome may provide valuable diagnostic clues to differentiate this relatively self-restricted disease from progressive degenerative disease like ALS.

  12. Myosin Binding Protein-C Slow Phosphorylation is Altered in Duchenne Dystrophy and Arthrogryposis Myopathy in Fast-Twitch Skeletal Muscles.

    PubMed

    Ackermann, Maegen A; Ward, Christopher W; Gurnett, Christina; Kontrogianni-Konstantopoulos, Aikaterini

    2015-08-19

    Myosin Binding Protein-C slow (sMyBP-C), encoded by MYBPC1, comprises a family of regulatory proteins of skeletal muscles that are phosphorylated by PKA and PKC. MYBPC1 missense mutations are linked to the development of Distal Arthrogryposis-1 (DA-1). Although structure-function details for this myopathy are evolving, function is undoubtedly driven by sequence variations and post-translational modifications in sMyBP-C. Herein, we examined the phosphorylation profile of sMyBP-C in mouse and human fast-twitch skeletal muscles. We used Flexor Digitorum Brevis (FDB) isolated from young (~2-months old) and old (~14-months old) wild type and mdx mice, and human Abductor Hallucis (AH) and gastrocnemious muscles carrying the DA-1 mutations. Our results indicate both constitutive and differential phosphorylation of sMyBP-C in aged and diseased muscles. We report a 7-35% reduction in the phosphorylation levels of select sites in old wild type and young or old mdx FDB mouse muscles, compared to young wild type tissue. Similarly, we observe a 30-70% decrease in the phosphorylation levels of all PKA and PKC phospho-sites in the DA-1 AH, but not gastrocnemius, muscle. Overall, our studies show that the phosphorylation pattern of sMyBP-C is differentially regulated in response to age and disease, suggesting that phosphorylation plays important roles in these processes.

  13. Jar-opening challenges. Part 2: estimating the force-generating capacity of thumb muscles in healthy young adults during jar-opening tasks.

    PubMed

    Kuo, L C; Chang, J H; Lin, C F; Hsu, H Y; Ho, K Y; Su, F C

    2009-07-01

    This study discusses the force-generating capacity of thumb muscles during jar-opening tasks using two grip patterns: the power grip and the precision grip. This study develops a three-dimensional biomechanical model of the thumb to predict muscle forces in jar-opening activities based on external forces measured by a custom-designed jar device. Ten healthy subjects participated in the study. Each participant turned a jar lid of 66 mm diameter counterclockwise with maximal effort and preferred speed using both grip patterns. The average normal and tangential forces applied by the thumb to the jar lid show that the normal force is the primary contributive force for opening a jar. This normal force is approximately three times the tangential force. Muscular force-generating capacity measurements show that the major active muscles during a jar-opening activity for both grips include the flexor pollicis longus, flexor pollicis brevis, abductor pollicis brevis, adductor pollicis, and opponens pollicis. The total muscle force ratios for the precision grip and power grip with respect to externally applied forces are 5.6 and 4.7 respectively. These ratios indicate that the power grip pattern produces less muscle force per unit of external applied load. The technique proposed in this study provides a proper apparatus and model for measuring three-dimensional loads and estimating the force-generating capacity of each muscle and tendon of the thumb during jar-opening tasks.

  14. Myosin Binding Protein-C Slow Phosphorylation is Altered in Duchenne Dystrophy and Arthrogryposis Myopathy in Fast-Twitch Skeletal Muscles

    PubMed Central

    Ackermann, Maegen A.; Ward, Christopher W.; Gurnett, Christina; Kontrogianni-Konstantopoulos, Aikaterini

    2015-01-01

    Myosin Binding Protein-C slow (sMyBP-C), encoded by MYBPC1, comprises a family of regulatory proteins of skeletal muscles that are phosphorylated by PKA and PKC. MYBPC1 missense mutations are linked to the development of Distal Arthrogryposis-1 (DA-1). Although structure-function details for this myopathy are evolving, function is undoubtedly driven by sequence variations and post-translational modifications in sMyBP-C. Herein, we examined the phosphorylation profile of sMyBP-C in mouse and human fast-twitch skeletal muscles. We used Flexor Digitorum Brevis (FDB) isolated from young (~2-months old) and old (~14-months old) wild type and mdx mice, and human Abductor Hallucis (AH) and gastrocnemious muscles carrying the DA-1 mutations. Our results indicate both constitutive and differential phosphorylation of sMyBP-C in aged and diseased muscles. We report a 7–35% reduction in the phosphorylation levels of select sites in old wild type and young or old mdx FDB mouse muscles, compared to young wild type tissue. Similarly, we observe a 30–70% decrease in the phosphorylation levels of all PKA and PKC phospho-sites in the DA-1 AH, but not gastrocnemius, muscle. Overall, our studies show that the phosphorylation pattern of sMyBP-C is differentially regulated in response to age and disease, suggesting that phosphorylation plays important roles in these processes. PMID:26287277

  15. The effective neural drive to muscles is the common synaptic input to motor neurons

    PubMed Central

    Farina, Dario; Negro, Francesco; Dideriksen, Jakob Lund

    2014-01-01

    We analysed the transformation of synaptic input to the pool of motor neurons into the neural drive to the muscle. The aim was to explain the relations between common oscillatory signals sent to motor neurons and the effective component of the neural signal sent to muscles as output of the spinal cord circuitries. The approach is based on theoretical derivations, computer simulations, and experiments. It is shown theoretically that for frequencies smaller than the average discharge rates of the motor neurons, the pool of motor neurons determines a pure amplification of the frequency components common to all motor neurons, so that the common input is transmitted almost undistorted and the non-common components are strongly attenuated. The effective neural drive to the muscle thus mirrors the common synaptic input to motor neurons. The simulations with three models of motor neuron confirmed the theoretical results by showing that the coherence function between common input components and the neural drive to the muscle tends to 1 when increasing the number of active motor neurons. This result, which was relatively insensitive to the type of model used, was also supported experimentally by observing that, in the low-pass signal bandwidth, the peak in coherence between groups of motor units of the abductor digiti minimi muscle of five healthy subjects tended to 1 when increasing the number of motor units. These results have implications for our understanding of the neural control of muscles as well as for methods used for estimating the strength of common input to populations of motor neurons. PMID:24860172

  16. Cortical control of erector spinae muscles during arm abduction in humans.

    PubMed

    Kuppuswamy, Annapoorna; Catley, Maria; King, Nicolas K K; Strutton, Paul H; Davey, Nick J; Ellaway, Peter H

    2008-04-01

    Abduction of one arm preferentially activates erector spinae muscles on the other side to stabilise the body. We hypothesise that the corticospinal drive to the arm abductors and the erector spinae may originate from the same hemisphere. In 18 subjects, transcranial magnetic stimulation (TMS) was applied using an angle double-cone coil placed symmetrically over the vertex. Motor evoked potentials (MEP) could not be evoked systematically seated at rest but could be evoked bilaterally in erector spinae muscles during unilateral arm abduction. TMS was applied at 110% and 120% motor threshold (MT) for the contralateral erector spinae muscle when an arm was abducted against resistance. The electromyographic (EMG) activity in the erector spinae at L4 vertebral level during contralateral arm abduction was significantly higher (P<0.05) than in the ipsilateral erector spinae. The mean (+/-S.E.M.) latencies of MEPs in the contralateral muscle to TMS at 120%MT (left 16.0+/-0.8 ms; right 17.0+/-0.8 ms) were significantly (P<0.05) longer than in the ipsilateral erector spinae (13.9+/-1.0 ms; 16.6+/-0.4 ms). In two of six subjects from the same group, it was possible to elicit MEPs by TMS applied selectively to one hemisphere using a figure-of-eight coil. MEPs ipsilateral to the TMS had longer latencies than contralateral MEPs. The study revealed an unexpectedly longer rather than shorter latency of the MEP recorded from the lumbar erector spinae muscles when co-activated during abduction of the opposite arm. A speculative explanation is that TMS might activate back muscles contralateral to arm abduction via an uncrossed, ipsilateral corticospinal tract that is slower conducting than the conventional crossed corticospinal tract. The study has implications for the design of measures to promote recovery and rehabilitation of motor function in disorders such as stroke and spinal cord injury.

  17. Accommodation: The role of the external muscles of the eye: A consideration of refractive errors in relation to extraocular malfunction.

    PubMed

    Hargrave, B K

    2014-11-01

    Speculation as to optical malfunction has led to dissatisfaction with the theory that the lens is the sole agent in accommodation and to the suggestion that other parts of the eye are also conjointly involved. Around half-a-century ago, Robert Brooks Simpkins suggested that the mechanical features of the human eye were precisely such as to allow for a lengthening of the globe when the eye accommodated. Simpkins was not an optical man but his theory is both imaginative and comprehensive and deserves consideration. It is submitted here that accommodation is in fact a twofold process, and that although involving the lens, is achieved primarily by means of a give - and - take interplay between adducting and abducting external muscles, whereby an elongation of the eyeball is brought about by a stretching of the delicate elastic fibres immediately behind the cornea. The three muscles responsible for convergence (superior, internal and inferior recti) all pull from in front backwards, while of the three abductors (external rectus and the two obliques) the obliques pull from behind forwards, allowing for an easy elongation as the eye turns inwards and a return to its original length as the abducting muscles regain their former tension, returning the eye to distance vision. In refractive errors, the altered length of the eyeball disturbs the harmonious give - and - take relationship between adductors and abductors. Such stresses are likely to be perpetuated and the error exacerbated. Speculation is not directed towards a search for a possible cause of the muscular imbalance, since none is suspected. Muscles not used rapidly lose tone, as evidenced after removal of a limb from plaster. Early attention to the need for restorative exercise is essential and results usually impressive. If flexibility of the external muscles of the eyes is essential for continuing good sight, presbyopia can be avoided and with it the supposed necessity of glasses in middle life. Early attention

  18. Inspiratory muscle strength in chronic obstructive pulmonary disease.

    PubMed

    Larson, Janet L; Covey, Margaret K; Corbridge, Susan

    2002-05-01

    Chronic obstructive pulmonary disease is associated with a functional weakness of the inspiratory muscles. Multiple factors contribute to the decline in functional strength including hyperinflation of the chest, deterioration in nutritional status, and the indirect effects of an exacerbation. The decreased inspiratory muscle strength contributes to sensations of dyspnea and places individuals at risk for respiratory muscle fatigue. The worsening dyspnea causes individuals to reduce their physical activities and ultimately become physically deconditioned. Maximal inspiratory pressure is commonly used to measure functional strength of the inspiratory muscles, and interventions to minimize the extent of decline include inspiratory muscle training, aerobic exercise training, nutritional supplementation, and methods to prevent exacerbations. In the critical care unit, multiple comorbid conditions contribute to further decline in inspiratory muscle strength, making it important to assess respiratory muscle function regularly.

  19. Detecting weakly interacting massive particles.

    NASA Astrophysics Data System (ADS)

    Drukier, A. K.; Gelmini, G. B.

    The growing synergy between astrophysics, particle physics, and low background experiments strengthens the possibility of detecting astrophysical non-baryonic matter. The idea of direct detection is that an incident, massive weakly interacting particle could collide with a nucleus and transfer an energy that could be measured. The present low levels of background achieved by the PNL/USC Ge detector represent a new technology which yields interesting bounds on Galactic cold dark matter and on light bosons emitted from the Sun. Further improvements require the development of cryogenic detectors. The authors analyse the practicality of such detectors, their optimalization and background suppression using the "annual modulation effect".

  20. Diffuse skeletal muscles uptake of [18F] fluorodeoxyglucose on positron emission tomography in primary muscle peripheral T-cell lymphoma.

    PubMed

    Tanaka, Yuji; Hayashi, Yuichi; Kato, Jun'ichi; Yamada, Megumi; Koumura, Akihiro; Sakurai, Takeo; Kimura, Akio; Hozumi, Isao; Hatano, Yuichiro; Hirose, Yoshinobu; Takami, Tsuyoshi; Nakamura, Hiroshi; Kasahara, Senji; Tsurumi, Hisashi; Moriwaki, Hisataka; Inuzuka, Takashi

    2011-01-01

    A 40-year-old man presented with weakness of neck extensor muscles. Cervical magnetic resonance imaging showed high-intensity areas in muscles of the left lateral cervical region on T2-weighted images. Fluorodeoxyglucose-positron emission tomography scan demonstrated striking fluorodeoxyglucose uptake by multiple skeletal muscles of the neck, chest, and abdominal region. Muscle biopsy demonstrated peripheral T-cell lymphoma, unspecified. The diagnosis was primary skeletal muscle peripheral T-cell lymphoma. Primary skeletal muscle non-Hodgkin's lymphoma of T-cell immunophenotype is extremely rare and fluorodeoxyglucose-positron emission tomography demonstrated striking fluorodeoxyglucose uptake in multiple skeletal muscles and served as a quite useful modality for the diagnosis of this patient.

  1. Gum chewing and jaw muscle fatigue and pains.

    PubMed

    Christensen, L V; Tran, K T; Mohamed, S E

    1996-06-01

    To study possible associations between gum chewing and fatigue and pains in the jaw muscles, eight healthy adults performed prolonged idling, prolonged unilateral chewing of gum, and brief vigorous clenching of the teeth (MVC). Through surface electromyography (EMG), the authors monitored the cumulative (microV.s) as well as the average rates (microV.s-1) of contractile activities in the right and left masseter muscles. During 10 min of idling there was an absence of muscle fatigue and muscle pains when the EMG rates of the right and left masseter muscles were 2% and 3%, respectively, of those required to elicit isometric muscle pains through MVC. During 10 min of right-sided gum chewing at a rate of 1.2 Hz, the majority of subjects (75%) experienced weak jaw muscle fatigue-not jaw muscle pains-when the EMG rates of the right and left masseter muscles were 38% and 19%, respectively, of those required to elicit isometric pains through MVC. In comparison with 10 min of idling, the weak muscle fatigue of 10 min of unilateral gum chewing appeared when the total contractile activities of the right and left masseter muscles were increased by 1664% and 519%, respectively. It seemed as if prolonged unilateral gum chewing and previous pain-releasing MVC caused some sensitization of muscle nociceptors which, in turn, aggravated subsequent isometric jaw muscle pains elicited through MVC. Even though the right masseter muscle was the most frequent site of clinical fatigue and pains, the authors found no evidence supporting the theoretical foundation of the myofascial pain/dysfunction syndrome.

  2. Vitamin D and Muscle Function.

    PubMed

    Dawson-Hughes, Bess

    2017-03-21

    Muscle weakness is a hallmark of severe vitamin D deficiency, but the effect of milder vitamin D deficiency or insufficiency on muscle mass and performance and risk of falling is uncertain. In this presentation, I review the evidence that vitamin D influences muscle mass and performance, balance, and risk of falling in older adults. Special consideration is given to the impact of both the starting 25-hydroxyvitamin D [25(OH)D] level and the dose administered on the clinical response to supplemental vitamin D in older men and women. Based on available evidence, older adults with serum 25(OH)D levels <40nmol/L appear most likely to improve their muscle performance with supplementation. The vitamin D dose range of 800-1000 IU per day has been effective in many studies; lower doses have generally been ineffective and several doses above this range have increased the risk of falls. In conclusion, older adults with serum 25(OH)D levels <40nmol/L are likely to have fewer falls if supplemented with 800 to 1,000 IU per day of vitamin D.

  3. Sex Differences in Exercise-Induced Muscle Pain and Muscle Damage

    PubMed Central

    Dannecker, Erin A.; Liu, Ying; Rector, R. Scott; Thomas, Tom R.; Fillingim, Roger B.; Robinson, Michael E.

    2012-01-01

    There is uncertainty about sex differences in exercise-induced muscle pain and muscle damage due to several methodological weaknesses in the literature. This investigation tested the hypothesis that higher levels of exercise-induced muscle pain and muscle damage indicators would be found in women than men when several methodological improvements were executed in the same study. Participants (N = 33; 42% women) with an average age of 23 years (SD = 2.82) consented to participate. After a familiarization session, participants visited the laboratory before and across four days after eccentric exercise was completed to induce arm muscle pain and muscle damage. Our primary outcomes were arm pain ratings and pressure pain thresholds. However, we also measured the following indicators of muscle damage: arm girth; resting elbow extension; isometric elbow flexor strength; myoglobin (Mb); tumor necrosis factor (TNFa); interleukin 1beta (IL1b); and total nitric oxide (NO). Temporary induction of muscle damage was indicated by changes in all outcome measures except TNFa, and IL1b. In contrast to our hypotheses, women reported moderately lower and less frequent muscle pain than men. Also, women’s arm girth and Mb levels increased moderately less than men’s, but the differences were not significant. Few large sex differences were detected. PMID:23182229

  4. Effects of Nordic walking on pelvis motion and muscle activities around the hip joints of adults with hip osteoarthritis

    PubMed Central

    Homma, Daisuke; Jigami, Hirofumi; Sato, Naritoshi

    2016-01-01

    [Purpose] Increased compensatory pelvic movement is remarkable in limping patients with hip osteoarthritis (OA). However, a method of improving limping has not been established. The purpose of this study was to identify the effects of two types of Nordic walking by analyzing the pelvic movement and muscle activities of adults with hip OA. [Subjects and Methods] Ten patients with OA of the hip performed Japanese-style Nordic walking (JS NW), European-style Nordic walking (ES NW), and Ordinary walking (OW), and the muscle activities around the hip joint and pelvic movements were analyzed. [Results] The pelvic rotation angle was significantly larger in ES NW than in JS NW. In the stance phase, hip abductor muscle activity was significantly decreased in JS NW compared to both OW and ES NW. In the swing phase, rectus abdominis muscle activity was significantly increased in both JS NW and ES NW compared to OW and lumbar erector spinae activity was significantly lower in JS NW than in OW. [Conclusion] JS NW style may reduce the compensatory pelvic rotation in patients with hip OA. JS NW might be better for joint protection and prevention of secondary disorders of the hip in OA patients. PMID:27190455

  5. Weak interactions at the SSC

    SciTech Connect

    Chanowitz, M.S.

    1986-03-01

    Prospects for the study of standard model weak interactions at the SSC are reviewed, with emphasis on the unique capability of the SSC to study the mechanism of electroweak symmetry breaking whether the associated new quanta are at the TeV scale or higher. Symmetry breaking by the minimal Higgs mechanism and by related strong interaction dynamical variants is summarized. A set of measurements is outlined that would calibrate the proton structure functions and the backgrounds to new physics. The ability to measure the three weak gauge boson vertex is found to complement LEP II, with measurements extending to larger Q/sup 2/ at a comparable statistical level in detectable decays. B factory physics is briefly reviewed as one example of a possible broad program of high statistics studies of sub-TeV scale phenomena. The largest section of the talk is devoted to the possible manifestations of symmetry breaking in the WW and ZZ production cross sections. Some new results are presented bearing on the ability to detect high mass WW and ZZ pairs. The principal conclusion is that although nonstandard model scenarios are typically more forgiving, the capability to study symmetry breaking in the standard model (and in related strong interaction dynamical variants) requires achieving the SSC design goals of ..sqrt.. s,L = 40Tev, 10/sup 33/cm/sup -2/sec/sup -1/. 28 refs., 5 figs.

  6. The weak scale from BBN

    NASA Astrophysics Data System (ADS)

    Hall, Lawrence J.; Pinner, David; Ruderman, Joshua T.

    2014-12-01

    The measured values of the weak scale, v, and the first generation masses, m u, d, e , are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of ( m u , m d , m e , v), catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of (1.4, 1.3, 2.5, ˜ 5), respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as v is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of m u, d, e that yield both hydrogen and heavy nuclei stability.

  7. Microfabricated artificial-muscle-based microvalve array

    NASA Astrophysics Data System (ADS)

    He, KeQin; Peteu, Serban F.; Madou, Marc J.

    2001-09-01

    Artificial muscle is defined herein as a blend of a hydrogel and a redox polymer, which dramatically swells and shrinks under environmental stimuli. This actuator can be applied to micro fabricating valves for controlled delivery systems. Previous work in our group has shown that a blend of poly(2- hydroxy ethyl)methacrylate (polyHEMA) and polyaniline displayed significant swelling and shrinking upon application of an electrochemical bias. In this type of artificial muscle, polyaniline, a redox polymer, acts as the 'electronic backbone' for transferring for most of the swelling and shrinking. However, polyHEMA showed only weak swelling an shrinking in a chemimechanical system, thus purpose of the current study is to enhance the artificial muscle actuating properties. An optimized hydrogel swelled up to 1000 percent in alkaline solution and contracted 70 percent in acid solution. An artificial muscle microvalve array was also micro fabricated and tested. These results could lead to a smart wireless drug delivery implanted system.

  8. Muscle strain treatment

    MedlinePlus

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  9. Eye muscle repair - discharge

    MedlinePlus

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  10. Oculopharyngeal Weakness, Hypophrenia, Deafness, and Impaired Vision: A Novel Autosomal Dominant Myopathy with Rimmed Vacuoles

    PubMed Central

    Chen, Ting; Lu, Xiang-Hui; Wang, Hui-Fang; Ban, Rui; Liu, Hua-Xu; Shi, Qiang; Wang, Qian; Yin, Xi; Pu, Chuan-Qiang

    2016-01-01

    Background: Myopathies with rimmed vacuoles are a heterogeneous group of muscle disorders with progressive muscle weakness and varied clinical manifestations but similar features in muscle biopsies. Here, we describe a novel autosomal dominant myopathy with rimmed vacuoles in a large family with 11 patients of three generations affected. Methods: A clinical study including family history, obstetric, pediatric, and development history was recorded. Clinical examinations including physical examination, electromyography (EMG), serum creatine kinase (CK), bone X-rays, and brain magnetic resonance imaging (MRI) were performed in this family. Open muscle biopsies were performed on the proband and his mother. To find the causative gene, the whole-exome sequencing was carried out. Results: Disease onset was from adolescence to adulthood, but the affected patients of the third generation presented an earlier onset and more severe clinical manifestations than the older generations. Clinical features were characterized as dysarthria, dysphagia, external ophthalmoplegia, limb weakness, hypophrenia, deafness, and impaired vision. However, not every patient manifested all symptoms. Serum CK was mildly elevated and EMG indicated a myopathic pattern. Brain MRI showed cerebellum and brain stem mildly atrophy. Rimmed vacuoles and inclusion bodies were observed in muscle biopsy. The whole-exome sequencing was performed, but the causative gene has not been found. Conclusions: We reported a novel autosomal dominant myopathy with rimmed vacuoles characterized by dysarthria, dysphagia, external ophthalmoplegia, limb weakness, hypophrenia, deafness, and impaired vision, but the causative gene has not been found and needs further study. PMID:27453229

  11. Exercise intolerance in Glycogen Storage Disease Type III: weakness or energy deficiency?

    PubMed

    Preisler, Nicolai; Pradel, Agnès; Husu, Edith; Madsen, Karen Lindhardt; Becquemin, Marie-Hélène; Mollet, Alix; Labrune, Philippe; Petit, Francois; Hogrel, Jean-Yves; Jardel, Claude; Maillot, Francois; Vissing, John; Laforêt, Pascal

    2013-05-01

    Myopathic symptoms in Glycogen Storage Disease Type IIIa (GSD IIIa) are generally ascribed to the muscle wasting that these patients suffer in adult life, but an inability to debranch glycogen likely also has an impact on muscle energy metabolism. We hypothesized that patients with GSD IIIa can experience exercise intolerance due to insufficient carbohydrate oxidation in skeletal muscle. Six patients aged 17-36-years were studied. We determined VO 2peak (peak oxygen consumption), the response to forearm exercise, and the metabolic and cardiovascular responses to cycle exercise at 70% of VO 2peak with either a saline or a glucose infusion. VO 2peak was below normal. Glucose improved the work capacity by lowering the heart rate, and increasing the peak work rate by 30% (108 W with glucose vs. 83 W with placebo, p=0.018). The block in muscle glycogenolytic capacity, combined with the liver involvement caused exercise intolerance with dynamic skeletal muscle symptoms (excessive fatigue and muscle pain), and hypoglycemia in 4 subjects. In this study we combined anaerobic and aerobic exercise to systematically study skeletal muscle metabolism and exercise tolerance in patients with GSD IIIa. Exercise capacity was significantly reduced, and our results indicate that this was due to a block in muscle glycogenolytic capacity. Our findings suggest that the general classification of GSD III as a glycogenosis characterized by fixed symptoms related to muscle wasting should be modified to include dynamic exercise-related symptoms of muscle fatigue. A proportion of the skeletal muscle symptoms in GSD IIIa, i.e. weakness and fatigue, may be related to insufficient energy production in muscle.

  12. A man with worsening weakness.

    PubMed

    Proietti, G; Puliti, M; Tulli, F; Silvestri, M

    1999-01-01

    The contemporary presence of organomegaly, skin manifestations, polyneuropathy, endocrinopathy and monoclonal component characterises the POEMS syndrome, often associated with osteosclerotic myeloma and Castelman's disease and more frequent in the Japanese. Clinical manifestations seem to be related to the production of many interleukins, mainly IL-1, IL-6 and TNF. Several endocrinopathies have been described, the most frequent being diabetes. Only one previous case of hypoparathyroidism associated with the syndrome has been described in medical reviews. Polyneuropathy is often sensitivo-motory and skin disease accounts for Raynaud phenomenon, skin pigmentation, hypertricosis and others. We describe the case of a 74-year-old man who underwent clinical examination for weakness mainly in the legs. Clinical and instrumental data showed rhabdomyolysis due to hypoparathyroidism. The contemporary presence of a monoclonal band of light chains on proteic electrophoresis, organomegaly and distal leg neuropathy allowed us to make a diagnosis of POEMS syndrome.

  13. Weakly nonlinear magnetohydrodynamic wave interactions

    SciTech Connect

    Webb, G.M.; Brio, M.; Kruse, M.T.; Zank, G.P.

    1999-06-01

    Equations describing weakly nonlinear magnetohydrodynamic (MHD) wave interactions in one Cartesian space dimension are discussed. For wave propagation in uniform media, the wave interactions of interest consist of: (a) three-wave resonant interactions in which high frequency waves, may evolve on long space and time scales if the wave phases satisfy the resonance conditions; (b) Burgers self-wave steepening for the magnetoacoustic waves, and (c) mean wave field effects, in which a particular wave interacts with the mean wave field of the other waves. For wave propagation in non-uniform media, further linear wave mixing terms appear in the equations. The equations describe four types of resonant triads: slow-fast magnetosonic wave interaction; Alfv{acute e}n-entropy wave interaction; Alfv{acute e}n-magnetosonic wave interaction; and magnetosonic-entropy wave interaction. The formalism is restricted to coherent wave interactions. {copyright} {ital 1999 American Institute of Physics.}

  14. [Patient of myofibrillar myopathy associated with muscle cramp and distal muscle involvement].

    PubMed

    Okada, Yoichiro; Ayaki, Takashi; Matsumoto, Riki; Ito, Hidefumi; Takahashi, Ryosuke; Nakano, Satoshi

    2012-01-01

    A 53-year-old man presented mild, but gradually worsening, distal-dominant upper bilateral limbs weakness and muscle cramp in both legs from the age of 30. He had no obvious muscle atrophy during the course of the disease. Muscle biopsy of the right lateral vastus muscle showed myopathic changes with round or helical hyaline inclusions in eosinophilic on H&E staining and dark green on modified Gomori trichrome. There were also non-rimmed vacuoles. NADH-TR showed lack of enzymic activity in areas corresponding to the inclusions. Immunohistochemistry demonstrated abnormal accumulation of desmin and myotilin in fibers with inclusions. Given these pathological findings, he was diagnosed with myofibrillar myopathy (MFM). Because MFM is genetically heterogeneous, its clinical manifestations are reported as variable. While MFM patients are sometimes reported to develop serious conditions such as severe weakness, cardiomyopathy or respiratory failure, which require a pacemaker or mechanical ventilator, our case only had mild distal dominant limb weakness and muscle cramps. Our patient suggests that we must consider MFM as a differential diagnosis in adult onset distal myopathies.

  15. Acute effects of muscle vibration on sensorimotor integration.

    PubMed

    Lapole, Thomas; Tindel, Jérémy

    2015-02-05

    Projections from the somesthetic cortex are believed to be involved in the modulation of motor cortical excitability by muscle vibration. The aim of the present pilot study was to analyse the effects of a vibration intervention on short-latency afferent inhibition (SAI), long-latency afferent inhibition (LAI), and afferent facilitation (AF), three intracortical mechanisms reflecting sensorimotor integration. Abductor pollicis brevis (APB) SAI, AF and LAI were investigated on 10 subjects by conditioning test transcranial magnetic stimulation pulses with median nerve electrical stimulation at inter-stimuli intervals in the range 15-25 ms, 25-60 ms, and 100-200 ms, respectively. Test motor evoked potentials (MEPs) were compared to unconditioned MEPs. Measurements were performed before and just after 15 min of vibration applied to the muscle belly of APB at a frequency of 80 Hz. SAI and LAI responses were significantly reduced compared to unconditioned test MEPs (P=0.039 and P<0.001, respectively). AF MEP amplitude was greater than SAI and LAI one (P=0.009 and P=0.004, respectively), but not different from test MEP (P=0.511). There was no significant main effect of vibration (P=0.905). However, 4 subjects were clearly identified as responders. Their mean vibration-induced increase was 324 ± 195% in APB SAI MEP amplitude, and 158 ± 53% and 319 ± 80% in AF and LAI, respectively. Significant differences in SAI, AF and LAI vibration-induced changes were found for responders when compared to non-responders (P=0.019, P=0.038, and P=0.01, respectively). A single session of APB vibration may increase sensorimotor integration, via decreased inhibition and increased facilitation. However, such results were not observed for all subjects, suggesting that other factors (such as attention to the sensory inputs) may have played a role.

  16. Bone mineral density, muscle strength, and recreational exercise in men

    NASA Technical Reports Server (NTRS)

    Snow-Harter, C.; Whalen, R.; Myburgh, K.; Arnaud, S.; Marcus, R.

    1992-01-01

    Muscle strength has been shown to predict bone mineral density (BMD) in women. We examined this relationship in 50 healthy men who ranged in age from 28 to 51 years (average 38.3 years). BMD of the lumbar spine, proximal femur, whole body, and tibia were measured by dual-energy x-ray absorptiometry (Hologic QDR 1000W). Dynamic strength using one repetition maximum was assessed for the biceps, quadriceps, and back extensors and for the hip abductors, adductors, and flexors. Isometric grip strength was measured by dynamometry. Daily walking mileage was assessed by 9 week stepmeter records and kinematic analysis of video filming. Subjects were designated as exercisers and nonexercisers. Exercisers participated in recreational exercise at least two times each week. The results demonstrated that BMD at all sites correlated with back and biceps strength (p < 0.01 to p = 0.0001). Body weight correlated with tibia and whole-body BMD (p < 0.001); age negatively correlated with Ward's triangle BMD (p < 0.01). In stepwise multiple regressions, back strength was the only independent predictor of spine and femoral neck density (R2 = 0.27). Further, back strength was the most robust predictor of BMD at the trochanter, Ward's triangle, whole body, and tibia, although biceps strength, age, body weight, and leg strength contributed significantly to BMD at these skeletal sites, accounting for 35-52% of the variance in BMD. Exercisers and nonexercisers were similar for walking (3.97 versus 3.94 miles/day), age (37.8 versus 38.5) years, and weight (80.0 versus 77.7 kg). However, BMD and muscle strength were significantly greater in exercises than in nonexercisers.(ABSTRACT TRUNCATED AT 250 WORDS).

  17. Effects of microgravity on rat muscle

    NASA Technical Reports Server (NTRS)

    Riley, D. A.

    1990-01-01

    It is well known that humans exposed to long term spaceflight experience undesirable progressive muscle weakness and increased fatigability. This problem has prompted the implementation of inflight exercise programs because most investigators believe that the major cause of diminished muscle performance is a combination of disuse and decreased workload. Inflight exercise has improved muscle health, but deficits have persisted, indicating that either the regimens utilized were suboptimal or there existed additional debilitating factors which were not remedied by exercise. Clarification of this question requires an improved understanding of the cellular and molecular basis of spaceflight-induced muscle deterioration. To this end, multiple investigations have been performed on the muscles from rats orbited 5 to 22 days in Cosmos biosatellites and Spacelab-3 (2,4,5,8,10 to 14,16,18,19,21 to 23,25,27,28). The eight Cosmos 1887 investigations examined the structural and biochemical changes in skeletal and cardiac muscles of rats exposed to microgravity for 12.5 days and returned to terrestrial gravity 2.3 days before tissues were collected. Even though interpretation of these results was complicated by the combination of inflight and postflight induced alterations, the consensus is that there is marked heterogeneity in both degree and type of responses from the whole muscle level down to the molecular level. Collectively, the muscle investigations of Cosmos 1887 clearly illustrate the wide diversity of muscle tissue responses to spaceflight. Judging from the summary report of this mission, heterogeneity of responses is not unique to muscle tissue. Elucidating the mechanism underlying this heterogeneity holds the key to explaining adaptation of the organism to prolonged spaceflight.

  18. Functional and biochemical modifications in skeletal muscles from malarial mice.

    PubMed

    Brotto, Marco A P; Marrelli, Mauro T; Brotto, Leticia S; Jacobs-Lorena, Marcelo; Nosek, Thomas M

    2005-05-01

    Although it is well established that patients suffering from malaria experience skeletal muscle problems (contracture, aches, fatigue, weakness), detailed studies have not been performed to investigate changes in the contractile function and biochemical properties of intact and skinned skeletal muscles of mammals infected with malaria. To this end, we investigated such features in the extensor digitorium longus (EDL, fast-twitch, glyocolytic) and in the soleus (SOL, slow-twitch, oxidative) muscles from mice infected with Plasmodium berghei. We first studied maximal tetanic force (T(max)) produced by intact control and malaria-infected muscles before, during and after fatigue. Triton-skinned muscle fibres were isolated from these muscles and used to determine isometric contractile features as well as a basic biochemical profile as analysed by silver-enhanced SDS-PAGE. We found that the T(max) of intact muscles and the maximal Ca2+-activated force (F(max)) of Triton-skinned muscle fibres were reduced by approximately 50% in malarial muscles. In addition, the contractile proteins of Triton-skinned muscle fibres from malarial muscles were significantly less sensitive to Ca2+. Biochemical analysis revealed that there was a significant loss of essential contractile proteins (e.g. troponins and myosin) in Triton-skinned muscle fibres from malarial muscles as compared to controls. The biochemical alterations (i.e., reduction of essential contractile proteins) seem to explain well the functional modifications resolved in both intact muscles and Triton-skinned muscle fibres and may provide a suitable paradigm for the aetiology of muscle symptoms associated with malaria.

  19. Muscle shape consistency and muscle volume prediction of thigh muscles.

    PubMed

    Mersmann, F; Bohm, S; Schroll, A; Boeth, H; Duda, G; Arampatzis, A

    2015-04-01

    The present study investigated the applicability of a muscle volume prediction method using only the muscle length (L(M)), the maximum anatomical cross-sectional area (ACSA(max)), and a muscle-specific shape factor (p) on the quadriceps vastii. L(M), ACSA(max), muscle volume, and p were obtained from magnetic resonance images of the vastus intermedius (VI), lateralis (VL), and medialis (VM) of female (n = 20) and male (n = 17) volleyball athletes. The average p was used to predict muscle volumes (V(p)) using the equation V(p)  = p × ACSA(max)  × L(M). Although there were significant differences in the muscle dimensions between male and female athletes, p was similar and on average 0.582, 0.658, 0.543 for the VI, VL, and VM, respectively. The position of ACSA(max) showed low variability and was at 57%, 60%, and 81% of the thigh length for VI, VL, and VM. Further, there were no significant differences between measured and predicted muscle volumes with root mean square differences of 5-8%. These results suggest that the muscle shape of the quadriceps vastii is independent of muscle dimensions or sex and that the prediction method could be sensitive enough to detect changes in muscle volume related to degeneration, atrophy, or hypertrophy.

  20. Deterministic weak localization in periodic structures.

    PubMed

    Tian, C; Larkin, A

    2005-12-09

    In some perfect periodic structures classical motion exhibits deterministic diffusion. For such systems we present the weak localization theory. As a manifestation for the velocity autocorrelation function a universal power law decay is predicted to appear at four Ehrenfest times. This deterministic weak localization is robust against weak quenched disorders, which may be confirmed by coherent backscattering measurements of periodic photonic crystals.

  1. Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability

    PubMed Central

    Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

    2017-01-01

    Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 (n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 (n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability. PMID:28392766

  2. Weak D in the Tunisian population

    PubMed Central

    Ouchari, Mouna; Romdhane, Houda; Chakroun, Taher; Abdelkefi, Saida; Houissa, Batoul; Hmida, Slama; Yacoub, Saloua Jemni

    2015-01-01

    Background More than 90 weak D types have been discovered to date. As there are no published data on the frequencies of weak D types in the Tunisian population, the aim of this study was to determine the composition of weak D alleles in our population. Material and methods Blood samples from 1777 D+ and 223 D− blood donors were tested for markers 809G, 1154C, 8G, 602G, 667G, 446A, and 885T relative to translation start codon by polymerase chain reaction with sequence-specific primers to estimate the frequencies of weak D type 1, weak D type 2, weak D type 3, weak D type 4, weak D type 5 and weak D type 11 in our population. Twenty-three samples with positive reactions were re-evaluated by DNA sequencing of RHD exons 1–10 and adjacent intronic sequences. Results Among the D+ donor cohort, weak D type 4 was the most prevalent allele (n=33, 1.2%) followed by weak D type 2 (n=6, 0.17%), weak D type 1 (n=4, 0.11%), and weak D type 5 (n=1, 0.28%) and weak D type 11 (n=1, 0.28%). RHD sequencing identified a weak D type 4.0 allele in all 19 samples tested. Among the D− pool, comprising 223 samples, we detected one sample with weak D type 4.0 associated with a C+c+E−e+ phenotype which had been missed by routine serological methods. Discussion Weak D type 4.0 appears to be the most prevalent weak D in our population. However, all samples must be sequenced in order to determine the exact subtype of weak D type 4, since weak D type 4.2 has considerable clinical importance, being associated with anti-D alloimmunisation. One case of weak D type 4 associated with dCe in trans had been missed by serology, so quality control of serological tests should be developed in our country. PMID:25369614

  3. Leaky ryanodine receptors contribute to diaphragmatic weakness during mechanical ventilation

    PubMed Central

    Matecki, Stefan; Dridi, Haikel; Jung, Boris; Saint, Nathalie; Reiken, Steven R.; Scheuermann, Valérie; Mrozek, Ségolène; Umanskaya, Alisa; Petrof, Basil J.; Jaber, Samir; Marks, Andrew R.; Lacampagne, Alain

    2016-01-01

    Ventilator-induced diaphragmatic dysfunction (VIDD) refers to the diaphragm muscle weakness that occurs following prolonged controlled mechanical ventilation (MV). The presence of VIDD impedes recovery from respiratory failure. However, the pathophysiological mechanisms accounting for VIDD are still not fully understood. Here, we show in human subjects and a mouse model of VIDD that MV is associated with rapid remodeling of the sarcoplasmic reticulum (SR) Ca2+ release channel/ryanodine receptor (RyR1) in the diaphragm. The RyR1 macromolecular complex was oxidized, S-nitrosylated, Ser-2844 phosphorylated, and depleted of the stabilizing subunit calstabin1, following MV. These posttranslational modifications of RyR1 were mediated by both oxidative stress mediated by MV and stimulation of adrenergic signaling resulting from the anesthesia. We demonstrate in the murine model that such abnormal resting SR Ca2+ leak resulted in reduced contractile function and muscle fiber atrophy for longer duration of MV. Treatment with β-adrenergic antagonists or with S107, a small molecule drug that stabilizes the RyR1–calstabin1 interaction, prevented VIDD. Diaphragmatic dysfunction is common in MV patients and is a major cause of failure to wean patients from ventilator support. This study provides the first evidence to our knowledge of RyR1 alterations as a proximal mechanism underlying VIDD (i.e., loss of function, muscle atrophy) and identifies RyR1 as a potential target for therapeutic intervention. PMID:27457930

  4. Aging and muscle: a neuron’s perspective

    PubMed Central

    Manini, TM; Hong, SL; Clark, BC

    2013-01-01

    Purpose of review Age-related muscle weakness causes a staggering economic, public, and personal burden. Most research has focused on internal muscular mechanisms as the root cause to strength loss. Here, we briefly discuss age-related impairments in the brain and peripheral nerve structures that may theoretically lead to muscle weakness in old age. Recent findings Neuronal atrophy in the brain is accompanied by electrical noise tied to declines in dopaminergic neurotransmission that degrades communication between neurons. Additionally, sensorimotor feedback loops that help regulate corticospinal excitability are impaired. In the periphery, there is evidence for motor unit loss, axonal atrophy, demyelination caused by oxidative damage to proteins and lipids, and modified transmission of the electrical signal through the neuromuscular junction. Summary Recent evidence clearly indicates that muscle weakness associated with aging is not entirely explained by classically postulated atrophy of muscle. In this issue, which focuses on ‘Ageing: Biology and Nutrition’ we will highlight new findings on how nervous system changes contribute to the aging muscle phenotype. These findings indicate that the ability to communicate neural activity to skeletal muscle is impaired with advancing age, which raises the question of whether many of these age-related neurological changes are mechanistically linked to impaired performance of human skeletal muscle. Collectively, this work suggests that future research should explore the direct link of these ‘upstream’ neurological adaptions and onset of muscle weakness in elders. In the long term, this new focus might lead to novel strategies to attenuate the age-related loss of muscle strength. PMID:23222705

  5. Weakly relativistic dispersion of Bernstein waves

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.

    1988-01-01

    Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.

  6. Advancements in stem cells treatment of skeletal muscle wasting

    PubMed Central

    Meregalli, Mirella; Farini, Andrea; Sitzia, Clementina; Torrente, Yvan

    2014-01-01

    Muscular dystrophies (MDs) are a heterogeneous group of inherited disorders, in which progressive muscle wasting and weakness is often associated with exhaustion of muscle regeneration potential. Although physiological properties of skeletal muscle tissue are now well known, no treatments are effective for these diseases. Muscle regeneration was attempted by means transplantation of myogenic cells (from myoblast to embryonic stem cells) and also by interfering with the malignant processes that originate in pathological tissues, such as uncontrolled fibrosis and inflammation. Taking into account the advances in the isolation of new subpopulation of stem cells and in the creation of artificial stem cell niches, we discuss how these emerging technologies offer great promises for therapeutic approaches to muscle diseases and muscle wasting associated with aging. PMID:24575052

  7. Acute femoral neuropathy secondary to an iliacus muscle hematoma.

    PubMed

    Seijo-Martínez, M; Castro del Río, M; Fontoira, E; Fontoira, M

    2003-05-15

    We present a patient with a spontaneous iliacus muscle hematoma, appearing immediately after a minor physical maneuver, presenting with pain and femoral neuropathy initially evidenced by massive quadriceps muscle fasciculations. A magnetic resonance imaging (MRI) study of the pelvic area confirmed the diagnosis, showing a hematoma secondary to a partial muscle tear. The patient was managed conservatively, and the continuous muscle activity ceased in 3 days, with progressive improvement of the pain and weakness. The recovery was complete. Femoral neuropathy is uncommon and usually due to compression from psoas muscle mass lesions of diverse nature, including hematomas. Usually subacute, femoral neuropathy may present acutely in cases of large or strategically placed compressive femoral nerve lesions, and may require surgical evacuation. The case presented herein is remarkable since the muscle hematoma appeared after a nonviolent maneuver, fasciculations were present at onset, and conservative management was sufficient for a full recovery.

  8. A Universe without Weak Interactions

    SciTech Connect

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-04-07

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  9. Weak percolation on multiplex networks

    NASA Astrophysics Data System (ADS)

    Baxter, Gareth J.; Dorogovtsev, Sergey N.; Mendes, José F. F.; Cellai, Davide

    2014-04-01

    Bootstrap percolation is a simple but nontrivial model. It has applications in many areas of science and has been explored on random networks for several decades. In single-layer (simplex) networks, it has been recently observed that bootstrap percolation, which is defined as an incremental process, can be seen as the opposite of pruning percolation, where nodes are removed according to a connectivity rule. Here we propose models of both bootstrap and pruning percolation for multiplex networks. We collectively refer to these two models with the concept of "weak" percolation, to distinguish them from the somewhat classical concept of ordinary ("strong") percolation. While the two models coincide in simplex networks, we show that they decouple when considering multiplexes, giving rise to a wealth of critical phenomena. Our bootstrap model constitutes the simplest example of a contagion process on a multiplex network and has potential applications in critical infrastructure recovery and information security. Moreover, we show that our pruning percolation model may provide a way to diagnose missing layers in a multiplex network. Finally, our analytical approach allows us to calculate critical behavior and characterize critical clusters.

  10. Testing the weak equivalence principle

    NASA Astrophysics Data System (ADS)

    Nobili, Anna M.; Comandi, Gian Luca; Pegna, Raffaello; Bramanti, Donato; Doravari, Suresh; Maccarone, Francesco; Lucchesi, David M.

    2010-01-01

    The discovery of Dark Energy and the fact that only about 5% of the mass of the universe can be explained on the basis of the current laws of physics have led to a serious impasse. Based on past history, physics might indeed be on the verge of major discoveries; but the challenge is enormous. The way to tackle it is twofold. On one side, scientists try to perform large scale direct observations and measurements - mostly from space. On the other, they multiply their efforts to put to the most stringent tests ever the physical theories underlying the current view of the physical world, from the very small to the very large. On the extremely small scale very exciting results are expected from one of the most impressive experiments in the history of mankind: the Large Hadron Collider. On the very large scale, the universe is dominated by gravity and the present impasse undoubtedly calls for more powerful tests of General Relativity - the best theory of gravity to date. Experiments testing the Weak Equivalence Principle, on which General Relativity ultimately lies, have the strongest probing power of them all; a breakthrough in sensitivity is possible with the “Galileo Galilei” (GG) satellite experiment to fly in low Earth orbit.

  11. Brief report: Blockade of Notch signaling in muscle stem cells causes muscular dystrophic phenotype and impaired muscle regeneration.

    PubMed

    Lin, Shuibin; Shen, Huangxuan; Jin, Baofeng; Gu, Yumei; Chen, Zirong; Cao, Chunxia; Hu, Chengbin; Keller, Charles; Pear, Warren S; Wu, Lizi

    2013-04-01

    Muscular dystrophies are a group of devastating diseases characterized by progressive muscle weakness and degeneration, with etiologies including muscle gene mutations and regenerative defects of muscle stem cells. Notch signaling is critical for skeletal myogenesis and has important roles in maintaining the muscle stem cell pool and preventing premature muscle differentiation. To investigate the functional impact of Notch signaling blockade in muscle stem cells, we developed a conditional knock-in mouse model in which endogenous Notch signaling is specifically blocked in muscle stem cell compartment. Mice with Notch signaling inhibition in muscle stem cells showed several muscular dystrophic features and impaired muscle regeneration. Analyses of satellite cells and isolated primary myoblasts revealed that Notch signaling blockade in muscle stem cells caused reduced activation and proliferation of satellite cells but enhanced differentiation of myoblasts. Our data thus indicate that Notch signaling controls processes that are critical to regeneration in muscular dystrophy, suggesting that Notch inhibitor therapies could have potential side effects on muscle functions.

  12. Mitochondrial ROS regulate oxidative damage and mitophagy but not age-related muscle fiber atrophy

    PubMed Central

    Sakellariou, Giorgos K.; Pearson, Timothy; Lightfoot, Adam P.; Nye, Gareth A.; Wells, Nicola; Giakoumaki, Ifigeneia I.; Vasilaki, Aphrodite; Griffiths, Richard D.; Jackson, Malcolm J.; McArdle, Anne

    2016-01-01

    Age-related loss of skeletal muscle mass and function is a major contributor to morbidity and has a profound effect on the quality of life of older people. The potential role of age-dependent mitochondrial dysfunction and cumulative oxidative stress as the underlying cause of muscle aging remains a controversial topic. Here we show that the pharmacological attenuation of age-related mitochondrial redox changes in muscle with SS31 is associated with some improvements in oxidative damage and mitophagy in muscles of old mice. However, this treatment failed to rescue the age-related muscle fiber atrophy associated with muscle atrophy and weakness. Collectively, these data imply that the muscle mitochondrial redox environment is not a key regulator of muscle fiber atrophy during sarcopenia but may play a key role in the decline of mitochondrial organelle integrity that occurs with muscle aging. PMID:27681159

  13. Pixelation Effects in Weak Lensing

    NASA Technical Reports Server (NTRS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-01-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, and Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09' for a 0.14' FWHM point-spread function (PSF). The pixel scale could be increased to 0.16' if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  14. Channelopathies of skeletal muscle excitability

    PubMed Central

    Cannon, Stephen C.

    2016-01-01

    Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K+ levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are “channelopathies” caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1) and several potassium channels (Kir2.1, Kir2.6, Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics. PMID:25880512

  15. Analysis of muscle fatigue in helicopter pilots.

    PubMed

    Balasubramanian, Venkatesh; Dutt, Ashwani; Rai, Shobhit

    2011-11-01

    Helicopter pilots espouse ergonomically unfavourable postures and endure vibration which result in low back pain. The objective of this study was to investigate the effects of a helicopter flight on pilots back and shoulder muscles using surface Electromyography (sEMG) analysis. This study also correlates low back pain symptoms from Rehabilitation Bioengineering Group Pain Scale (RBGPS) questionnaire with muscle fatigue rates obtained. RBGPS was administered on 20 Coast Guard helicopter pilots. sEMG was acquired before and after flight from erector spinae and trapezius muscles in 8 of these 20 pilots. Statistical analysis of time and frequency domain parameters indicated significant fatigue in right trapezius muscle due to flying. Muscle fatigue correlated with average duration of flight (r² = 0.913), total service as pilot (r² = 0.825), pain (r² = 0.463) and total flying hours (r² = 0.507). However, muscle fatigue weakly correlated with Body Mass Index (BMI) (r² = 0.000144) and age (r² = 0.033).

  16. Muscle fibrillin deficiency in Marfan's syndrome myopathy

    PubMed Central

    Behan, W; Longman, C; Petty, R; Comeglio, P; Child, A; Boxer, M; Foskett, P; Harriman, D

    2003-01-01

    Objective: To report a family with Marfan's syndrome in whom a myopathy was associated with respiratory failure; muscle biopsies from affected individuals were examined to determine whether there were abnormalities in fibrillin. Methods: 21 family members underwent detailed clinical examination, including neurological and pulmonary assessment. Muscle biopsies in the most severely affected cases were immunostained using monoclonal antibodies to specific fibrillin components. Genomic DNA from all 21 members was analysed for mutations in the fibrillin gene, FBN1, on 15q21. Results: 13 individuals had a C4621T base change in exon 37 of the FBN1 gene, which in four cases segregated with muscle weakness or evidence of respiratory muscle dysfunction or both. Their muscle biopsies revealed an abnormality in fibrillin immunoreactivity. Conclusions: Abnormalities in fibrillin can be detected in muscle biopsies from patients with Marfan's syndrome who have myopathy. This pedigree, with a point mutation in FBN1, also draws attention to the potential for respiratory failure associated with myopathy. PMID:12700307

  17. To what extent is mean EMG frequency during gait a reflection of functional muscle strength in children with cerebral palsy?

    PubMed

    Van Gestel, L; Wambacq, H; Aertbeliën, E; Meyns, P; Bruyninckx, H; Bar-On, L; Molenaers, G; De Cock, P; Desloovere, K

    2012-01-01

    The aim of the current paper was to analyze the potential of the mean EMG frequency, recorded during 3D gait analysis (3DGA), for the evaluation of functional muscle strength in children with cerebral palsy (CP). As walking velocity is known to also influence EMG frequency, it was investigated to which extent the mean EMG frequency is a reflection of underlying muscle strength and/or the applied walking velocity. Surface EMG data of the lateral gastrocnemius (LGAS) and medial hamstrings (MEH) were collected during 3DGA. For each muscle, 20 CP children characterized by a weak and 20 characterized by a strong muscle (LGAS or MEH) were selected. A weak muscle was defined as a manual muscle testing score <3; a strong muscle was defined as a manual muscle testing score ≥4. Patient selection was based on the following inclusion criteria: (a) predominantly spastic type of CP (3-15 years old), (b) either (near) normal muscle strength or muscle weakness in at least one of the studied lower limb muscles, (c) no lower limb Botulinum Toxin-A treatment within 6 months prior to the 3DGA, (d) no history of lower limb surgery, and (e) high-quality noise-free EMG-data. For each muscle, twenty age-related typically developing (TD) children were included as controls. In both muscles a consistent pattern of increasing mean EMG frequency with decreasing muscle strength was observed. This was significant in the LGAS (TD versus weak CP). Walking velocity also had a significant effect on mean EMG frequency in the LGAS. Furthermore, based on R(2) and partial correlations, it could be concluded that both walking velocity and muscle strength have an impact on EMG, but the contribution of muscle strength was always higher. These findings underscore the potential of the mean EMG frequency recorded during 3DGA, for the evaluation of functional muscle strength in children with CP.

  18. Classical field approach to quantum weak measurements.

    PubMed

    Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco

    2014-03-21

    By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.

  19. Weak gravitational lensing by galaxies

    SciTech Connect

    Brainerd, T.G. |; Blandford, R.D.; Smail, I. |

    1996-08-01

    We report a detection of weak, tangential distortion of the images of cosmologically distant, faint galaxies due to gravitational lensing by foreground galaxies. A mean image polarization of ({ital p})=0.011{plus_minus}0.006 (95{percent} confidence bounds) is obtained for 3202 pairs of source (23{lt}{ital r}{sub {ital s}}{le}24) and lens (20{le}{ital r}{sub {ital d}}{le}23) galaxies with projected separations of 5{double_prime}{le}{theta}{le}34{double_prime}. Averaged over annuli of inner radius 5{double_prime} and outer radius {theta}{sub max}, the signal is string for lens-source separations of {theta}{sub max}{approx_lt}90{double_prime} consistent with quasi-isothermal galaxy halos extending to large radii ({approx_gt}100{ital h}{sup {minus}1} kpc). The observed polarization is also consistent with the signal expected on the basis of simulations incorporating measured properties of local galaxies and modest extrapolations of the observed redshift distribution of faint galaxies (to which the results are somewhat sensitive). From the simulations we obtain formal best-fit model parameters for the dark halos of the lens galaxies that consist of a characteristic circular velocity of {ital V}{asterisk}{approximately}220{plus_minus}80 kms{sup {minus}1} and characteristic radial extent of {ital s}{asterisk}{approx_gt}100{ital h}{sup {minus}1} kpc. The predicted polarization based on the model is relatively insensitive to the characteristic radial extent of the halos, {ital s}{asterisk}, and very small halos ({ital s}{asterisk}{approximately}10{ital h}{sup {minus}1} kpc) are excluded only at the 2 {sigma} level. The formal best-fit halo parameters imply typical masses for the lens galaxies within a radius of 100{ital h}{sup -1} kpc on the order of 1.0{sup +1.2}{sub {minus}0.5}{times}10{sup 12} {ital h}{sup {minus}1}{ital M}{sub {circle_dot}} (90% confidence bounds), in agreement with recent dynamical estimates of the masses of local spiral galaxies.

  20. Nerve, muscle or bone disease? Look before you leap.

    PubMed

    Muthukrishnan, J; Harikumar, K V S; Sangeeta, J; Singh, M K; Modi, K

    2009-08-01

    Severe muscle weakness in osteomalacia may mimic a primary neuromuscular disorder like spinal muscular atrophy. A 32-year-old woman, initially diagnosed as a case of spinal muscular atrophy based on clinical presentation, electromyography and muscle biopsy, was later found to have osteomalacic myopathy due to primary hyperparathyroidism complicated by vitamin D deficiency. Before diagnosing a progressive, inevitably fatal degenerative condition like spinal muscular atrophy, one must rule out all possible treatable conditions with a similar presentation.

  1. Spin effects in the weak interaction

    SciTech Connect

    Freedman, S.J. Chicago Univ., IL . Dept. of Physics Chicago Univ., IL . Enrico Fermi Inst.)

    1990-01-01

    Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.

  2. INSPIRATIonAL--INSPIRAtory muscle training in amyotrophic lateral sclerosis.

    PubMed

    Cheah, Benjamin C; Boland, Robert A; Brodaty, Nina E; Zoing, Margie C; Jeffery, Sandra E; McKenzie, David K; Kiernan, Matthew C

    2009-01-01

    Respiratory impairment, due to respiratory muscle weakness, is a major cause of morbidity and mortality in patients with amyotrophic lateral sclerosis/motor neuron disease (ALS/MND). Threshold loading may strengthen the inspiratory muscles and thereby improve patient prognosis. A phase II, double-blind, randomized-controlled trial was undertaken to determine whether a 12-week inspiratory muscle training programme attenuated the decline in respiratory function and inspiratory muscle strength in patients with ALS/MND. Nine patients were randomized to inspiratory muscle training and 10 to sham training. Primary endpoints were respiratory function (forced vital capacity, vital capacity), lung volumes and inspiratory muscle strength. Patients were assessed before, during and immediately after a 12-week training period, and at eight weeks follow-up. While improvements in inspiratory muscle strength were observed in both treatment arms, there was a non-significant increase in maximum inspiratory pressure of 6.1% in the experimental group compared to controls (standard error of mean, 6.93%; 95% confidence interval -8.58 -20.79; p=0.39). The gains in inspiratory muscle strength were partially reversed during a period of training cessation. In conclusion, inspiratory muscle training may potentially strengthen the inspiratory muscles and slow the decline in respiratory function in patients with ALS/MND.

  3. Regulation of muscle atrophy in aging and disease.

    PubMed

    Vinciguerra, Manlio; Musaro, Antonio; Rosenthal, Nadia

    2010-01-01

    Muscle aging is characterized by a decline in functional performance and restriction of adaptability, due to progressive loss of muscle tissue coupled with a decrease in strength and force output. Together with selective activation ofapoptotic pathways, a hallmark of age-related muscle loss or sarcopenia is the progressive incapacity of regeneration machinery to replace damaged muscle. These characteristics are shared by pathologies involving muscle wasting, such as muscular dystrophies or amyotrophic lateral sclerosis, cancer and AIDS, all characterized by alterations in metabolic and physiological parameters, progressive weakness in specific muscle groups. Modulation ofextracellular agonists, receptors, protein kinases, intermediate molecules, transcription factors and tissue-specific gene expression collectively compromise the functionality of skeletal muscle tissue, leading to muscle degeneration and persistent protein degradation through activation ofproteolytic systems, such as calpain, ubiquitin-proteasome and caspase. Additional decrements in muscle growth factors compromise skeletal muscle growth, differentiation, survival and regeneration. A better understanding of the mechanisms underlying the pathogenesis of muscle atrophy and wasting associated with different diseases has been the objective of numerous studies and represents an important first step for the development of therapeutic approaches. Among these, insulin-like growth factor-1 (IGF-1) has emerged as a growth factor with a remarkably wide range of actions and a tremendous potential as a therapeutic in attenuating the atrophy and frailty associated with muscle aging and diseases. In this chapter we provide an overview of current concepts in muscle atrophy, focusing specifically on the molecular basis of IGF-1 action and survey current gene and cell therapeutic approaches to rescue muscle atrophy in aging and disease.

  4. Weak point target detection in star sensor

    NASA Astrophysics Data System (ADS)

    Liu, Da; Xiong, Yazhou; Li, Yi; Wang, Li; Li, Chunyan; Yin, Fang

    2016-11-01

    Space weak point targets detection is very useful in non cooperative target detection. Influenced by the chip noise and space environmental noise, weak point targets detection becomes a difficulty. In the paper, firstly the star is extracted from the picture, the background picture is filtered to reduce the noise, and then the moving distance between adjacent pictures is calculated, after picture overlapping between adjacent pictures, the energy of the weak point target is improved, with a appropriate threshold, the weak point target is extracted. The proposed method can be widely utilized in space exploration, space defense etc.

  5. Weak measurements and nonClassical correlations

    NASA Astrophysics Data System (ADS)

    Lekshmi, S.; Shaji, N.; Shaji, Anil

    2017-01-01

    We extend the definition of quantum discord as a quantifier of nonClassical correlations in a quantum state to the case where weak measurements are performed on subsystem A of a bipartite system AB. The properties of weak discord are explored for several families of quantum states. We find that in many cases weak quantum discord is identical to normal discord and in general the values of the two are very close to each other. Weak quantum discord reduces to discord in the appropriate limits as well. We also discuss the implications of these observations on the interpretations of quantum discord.

  6. The impact of obesity on skeletal muscle strength and structure through adolescence to old age.

    PubMed

    Tomlinson, D J; Erskine, R M; Morse, C I; Winwood, K; Onambélé-Pearson, Gladys

    2016-06-01

    Obesity is associated with functional limitations in muscle performance and increased likelihood of developing a functional disability such as mobility, strength, postural and dynamic balance limitations. The consensus is that obese individuals, regardless of age, have a greater absolute maximum muscle strength compared to non-obese persons, suggesting that increased adiposity acts as a chronic overload stimulus on the antigravity muscles (e.g., quadriceps and calf), thus increasing muscle size and strength. However, when maximum muscular strength is normalised to body mass, obese individuals appear weaker. This relative weakness may be caused by reduced mobility, neural adaptations and changes in muscle morphology. Discrepancies in the literature remain for maximal strength normalised to muscle mass (muscle quality) and can potentially be explained through accounting for the measurement protocol contributing to muscle strength capacity that need to be explored in more depth such as antagonist muscle co-activation, muscle architecture, a criterion valid measurement of muscle size and an accurate measurement of physical activity levels. Current evidence demonstrating the effect of obesity on muscle quality is limited. These factors not being recorded in some of the existing literature suggest a potential underestimation of muscle force either in terms of absolute force production or relative to muscle mass; thus the true effect of obesity upon skeletal muscle size, structure and function, including any interactions with ageing effects, remains to be elucidated.

  7. Smad2/3 Proteins Are Required for Immobilization-induced Skeletal Muscle Atrophy.

    PubMed

    Tando, Toshimi; Hirayama, Akiyoshi; Furukawa, Mitsuru; Sato, Yuiko; Kobayashi, Tami; Funayama, Atsushi; Kanaji, Arihiko; Hao, Wu; Watanabe, Ryuichi; Morita, Mayu; Oike, Takatsugu; Miyamoto, Kana; Soga, Tomoyoshi; Nomura, Masatoshi; Yoshimura, Akihiko; Tomita, Masaru; Matsumoto, Morio; Nakamura, Masaya; Toyama, Yoshiaki; Miyamoto, Takeshi

    2016-06-03

    Skeletal muscle atrophy promotes muscle weakness, limiting activities of daily living. However, mechanisms underlying atrophy remain unclear. Here, we show that skeletal muscle immobilization elevates Smad2/3 protein but not mRNA levels in muscle, promoting atrophy. Furthermore, we demonstrate that myostatin, which negatively regulates muscle hypertrophy, is dispensable for denervation-induced muscle atrophy and Smad2/3 protein accumulation. Moreover, muscle-specific Smad2/3-deficient mice exhibited significant resistance to denervation-induced muscle atrophy. In addition, expression of the atrogenes Atrogin-1 and MuRF1, which underlie muscle atrophy, did not increase in muscles of Smad2/3-deficient mice following denervation. We also demonstrate that serum starvation promotes Smad2/3 protein accumulation in C2C12 myogenic cells, an in vitro muscle atrophy model, an effect inhibited by IGF1 treatment. In vivo, we observed IGF1 receptor deactivation in immobilized muscle, even in the presence of normal levels of circulating IGF1. Denervation-induced muscle atrophy was accompanied by reduced glucose intake and elevated levels of branched-chain amino acids, effects that were Smad2/3-dependent. Thus, muscle immobilization attenuates IGF1 signals at the receptor rather than the ligand level, leading to Smad2/3 protein accumulation, muscle atrophy, and accompanying metabolic changes.

  8. Aging related changes in determinants of muscle force generating capacity: a comparison of muscle aging in men and male rodents.

    PubMed

    Ballak, Sam B; Degens, Hans; de Haan, Arnold; Jaspers, Richard T

    2014-03-01

    Human aging is associated with a progressive decline in skeletal muscle mass and force generating capacity, however the exact mechanisms underlying these changes are not fully understood. Rodents models have often been used to enhance our understanding of mechanisms of age-related changes in human skeletal muscle. However, to what extent age-related alterations in determinants of muscle force generating capacity observed in rodents resemble those in humans has not been considered thoroughly. This review compares the effect of aging on muscle force generating determinants (muscle mass, fiber size, fiber number, fiber type distribution and muscle specific tension), in men and male rodents at similar relative age. It appears that muscle aging in male F344*BN rat resembles that in men most; 32-35-month-old rats exhibit similar signs of muscle weakness to those of 70-80-yr-old men, and the decline in 36-38-month-old rats is similar to that in men aged over 80 yrs. For male C57BL/6 mice, age-related decline in muscle force generating capacity seems to occur only at higher relative age than in men. We conclude that the effects on determinants of muscle force differ between species as well as within species, but qualitatively show the same pattern as that observed in men.

  9. Leucine-enriched essential amino acids attenuate muscle soreness and improve muscle protein synthesis after eccentric contractions in rats.

    PubMed

    Kato, Hiroyuki; Suzuki, Hiromi; Mimura, Masako; Inoue, Yoshiko; Sugita, Mayu; Suzuki, Katsuya; Kobayashi, Hisamine

    2015-06-01

    Eccentric exercise results in prolonged muscle weakness and muscle soreness, which are typical symptoms of muscle damage. Recovery from muscle damage is related to mammalian target of rapamycin (mTOR) activity. Leucine-enriched essential amino acids (LEAAs) stimulate muscle protein synthesis via activation of the mTOR pathway. Therefore, we investigated the effect of LEAAs on muscle protein synthesis and muscle soreness after eccentric contractions (EC). Male Sprague-Dawley rats (9-11 weeks old) were administered an LEAA solution (AminoL40; containing 40 % leucine and 60 % other essential amino acids) at 1 g/kg body weight or distilled water (control) 30 min before and 10 min after EC. Tibialis anterior (TA) muscle was exposed to 500 EC by electrical stimulation under anesthesia. The fractional synthesis rate (FSR; %/h) in the TA muscle was measured by incorporating L-[ring-(2)H5] phenylalanine into skeletal muscle protein. Muscle soreness was evaluated by the paw withdrawal threshold using the Randal-Selitto test with some modifications from 1 to 3 days after EC. The FSR in the EC-control group (0.147 ± 0.016 %/h) was significantly lower than in the sedentary group (0.188 ± 0.016 %/h, p < 0.05). AminoL40 administration significantly mitigated the EC-induced impairment of the FSR (0.172 ± 0.018 %/h). EC decreased the paw withdrawal threshold at 1 and 2 days after EC, which indicated that EC induced muscle soreness. Furthermore, AminoL40 administration alleviated the decreased paw withdrawal threshold. These findings suggest that LEAA supplementation improves the rate of muscle protein synthesis and ameliorates muscle soreness after eccentric exercise.

  10. A Critical Role for Muscle Ring Finger-1 in Acute Lung Injury–associated Skeletal Muscle Wasting

    PubMed Central

    Files, D. Clark; D'Alessio, Franco R.; Johnston, Laura F.; Kesari, Priya; Aggarwal, Neil R.; Garibaldi, Brian T.; Mock, Jason R.; Simmers, Jessica L.; DeGorordo, Antonio; Murdoch, Jared; Willis, Monte S.; Patterson, Cam; Tankersley, Clarke G.; Messi, Maria L.; Liu, Chun; Delbono, Osvaldo; Furlow, J. David; Bodine, Sue C.; Cohn, Ronald D.; King, Landon S.

    2012-01-01

    Rationale: Acute lung injury (ALI) is a debilitating condition associated with severe skeletal muscle weakness that persists in humans long after lung injury has resolved. The molecular mechanisms underlying this condition are unknown. Objectives: To identify the muscle-specific molecular mechanisms responsible for muscle wasting in a mouse model of ALI. Methods: Changes in skeletal muscle weight, fiber size, in vivo contractile performance, and expression of mRNAs and proteins encoding muscle atrophy–associated genes for muscle ring finger-1 (MuRF1) and atrogin1 were measured. Genetic inactivation of MuRF1 or electroporation-mediated transduction of miRNA-based short hairpin RNAs targeting either MuRF1 or atrogin1 were used to identify their role in ALI-associated skeletal muscle wasting. Measurements and Main Results: Mice with ALI developed profound muscle atrophy and preferential loss of muscle contractile proteins associated with reduced muscle function in vivo. Although mRNA expression of the muscle-specific ubiquitin ligases, MuRF1 and atrogin1, was increased in ALI mice, only MuRF1 protein levels were up-regulated. Consistent with these changes, suppression of MuRF1 by genetic or biochemical approaches prevented muscle fiber atrophy, whereas suppression of atrogin1 expression was without effect. Despite resolution of lung injury and down-regulation of MuRF1 and atrogin1, force generation in ALI mice remained suppressed. Conclusions: These data show that MuRF1 is responsible for mediating muscle atrophy that occurs during the period of active lung injury in ALI mice and that, as in humans, skeletal muscle dysfunction persists despite resolution of lung injury. PMID:22312013

  11. Manual muscle testing: a method of measuring extremity muscle strength applied to critically ill patients.

    PubMed

    Ciesla, Nancy; Dinglas, Victor; Fan, Eddy; Kho, Michelle; Kuramoto, Jill; Needham, Dale

    2011-04-12

    Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge. Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. (7, 8) This video demonstrates a protocol for MMT, which has been taught to ≥ 43 research staff who have performed >800 assessments on >280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale. Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. (1,2).

  12. Human Muscle Fiber

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The stimulus of gravity affects RNA production, which helps maintain the strength of human muscles on Earth (top), as seen in this section of muscle fiber taken from an astronaut before spaceflight. Astronauts in orbit and patients on Earth fighting muscle-wasting diseases need countermeasures to prevent muscle atrophy, indicated here with white lipid droplets (bottom) in the muscle sample taken from the same astronaut after spaceflight. Kerneth Baldwin of the University of California, Irvine, is conducting research on how reducing the stimulus of gravity affects production of the RNA that the body uses as a blueprint for making muscle proteins. Muscle proteins are what give muscles their strength, so when the RNA blueprints aren't available for producing new proteins to replace old ones -- a situation that occurs in microgravity -- the muscles atrophy. When the skeletal muscle system is exposed to microgravity during spaceflight, the muscles undergo a reduced mass that translates to a reduction in strength. When this happens, muscle endurance decreases and the muscles are more prone to injury, so individuals could have problems in performing extravehicular activity [space walks] or emergency egress because their bodies are functionally compromised.

  13. Muscle strain injuries.

    PubMed

    Garrett, W E

    1996-01-01

    One of the most common injuries seen in the office of the practicing physician is the muscle strain. Until recently, little data were available on the basic science and clinical application of this basic science for the treatment and prevention of muscle strains. Studies in the last 10 years represent action taken on the direction of investigation into muscle strain injuries from the laboratory and clinical fronts. Findings from the laboratory indicate that certain muscles are susceptible to strain injury (muscles that cross multiple joints or have complex architecture). These muscles have a strain threshold for both passive and active injury. Strain injury is not the result of muscle contraction alone, rather, strains are the result of excessive stretch or stretch while the muscle is being activated. When the muscle tears, the damage is localized very near the muscle-tendon junction. After injury, the muscle is weaker and at risk for further injury. The force output of the muscle returns over the following days as the muscle undertakes a predictable progression toward tissue healing. Current imaging studies have been used clinically to document the site of injury to the muscle-tendon junction. The commonly injured muscles have been described and include the hamstring, the rectus femoris, gastrocnemius, and adductor longus muscles. Injuries inconsistent with involvement of a single muscle-tendon junction proved to be at tendinous origins rather than within the muscle belly. Important information has also been provided regarding injuries with poor prognosis, which are potentially repairable surgically, including injuries to the rectus femoris muscle, the hamstring origin, and the abdominal wall. Data important to the management of common muscle injuries have been published. The risks of reinjury have been documented. The early efficacy and potential for long-term risks of nonsteroidal antiinflammatory agents have been shown. New data can also be applied to the field

  14. A force/displacement analysis of muscle testing.

    PubMed

    Caruso, W; Leisman, G

    2000-10-01

    Manual muscle testing procedures are the subject of a force and displacement analysis. Equipment was fabricated, tested, and employed to gather force, displacement, and time data for the purpose of examining muscle-test parameters as used by clinicians in applied kinesiology. Simple mathematical procedures are used to process the data to find potential patterns of force and displacement which would correspond to the testing of strong and weak muscles of healthy subjects. Particular attention is paid to the leading edge of the force pulses, as most clinicians report they derive most of their assessment from the initial thrust imparted on the patient's limb. An analysis of the simple linear regression of the slope (distance vs force) of the leading edge of a force pulse indicates that a significantly large slope is indicative of weak muscles (as perceived by the clinician), and a small slope is indicative of strong muscles. Threshold criteria for slopes are specified to create a model that may discriminate between strong and weak muscles. The model is accurate 98% of the time compared to judgments of clinicians with more than 5 years of experience but is considerably lower for clinicians with less than five years of experience (64%). this accuracy rate indicates that the model is reliable in predicting the clinician's perception of muscle strength, and it also indicates that the testing procedure for muscle strength used by experienced clinicians in applied kinesiology are reliable. The experiment lays the groundwork for studies of the objectivity of muscle-strength assessment in applied kinesiology.

  15. A 64-Year-Old Woman with Chest Pain, Limb Weakness, and Endometrial Cancer

    PubMed Central

    Kherad, Omar; Petriccioli, Nicole; Lobrinus, Johannes Alexander; Guerne, Pierre-André A.

    2017-01-01

    Necrotizing autoimmune myopathy (NAM) is a rare subgroup of idiopathic inflammatory myopathies (IIM). This pathology usually affects proximal limb muscles and in some cases the myocardium. Patients usually display proximal limb weakness. Muscular biopsy is required to confirm the diagnosis. We report the case of a 64-year-old woman with an atypical first presentation of NAM, manifested by chest pain in the context of metastatic endometrial cancer. The diagnosis of NAM was however made when she returned a second time with proximal limb weakness. A treatment with prednisone was then initiated, to which rituximab was rapidly associated, beside a specific chemotherapy. PMID:28373922

  16. Healthy Muscles Matter

    MedlinePlus

    ... keep my muscles more healthy? Definitions What can go wrong? Injuries Almost everyone has had sore muscles ... If you have been inactive, “start low and go slow” by gradually increasing how often and how ...

  17. Respiratory muscle plasticity.

    PubMed

    Rowley, Katharine L; Mantilla, Carlos B; Sieck, Gary C

    2005-07-28

    Plasticity of respiratory muscles must be considered in the context of their unique physiological demands. The continuous rhythmic activation of respiratory muscles makes them among the most active in the body. Respiratory muscles, especially the diaphragm, are non-weight-bearing, and thus, in contrast to limb muscles, are not exposed to gravitational effects. Perturbations in normal activation and load known to induce plasticity in limb muscles may not cause similar adaptations in respiratory muscles. In this review, we explore the structural and functional properties of the diaphragm muscle and their response to alterations in load and activity. Overall, relatively modest changes in diaphragm structural and functional properties occur in response to perturbations in load or activity. However, disruptions in the normal influence of phrenic innervation by frank denervation, tetrodotoxin nerve block and spinal hemisection, induce profound changes in the diaphragm, indicating the substantial trophic influence of phrenic motoneurons on diaphragm muscle.

  18. Eye muscle repair - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100062.htm Eye muscle repair - series—Normal anatomy To use the sharing ... the eyeball to the eye socket. The external muscles of the eye are found behind the conjunctiva. ...

  19. CP Violation, Neutral Currents, and Weak Equivalence

    DOE R&D Accomplishments Database

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  20. On modeling weak sinks in MODPATH

    USGS Publications Warehouse

    Abrams, Daniel B.; Haitjema, Henk; Kauffman, Leon J.

    2012-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

  1. On modeling weak sinks in MODPATH.

    PubMed

    Abrams, Daniel; Haitjema, H; Kauffman, L

    2013-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low-resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

  2. Spin Seebeck effect in a weak ferromagnet

    NASA Astrophysics Data System (ADS)

    Arboleda, Juan David; Arnache Olmos, Oscar; Aguirre, Myriam Haydee; Ramos, Rafael; Anadon, Alberto; Ibarra, Manuel Ricardo

    2016-06-01

    We report the observation of room temperature spin Seebeck effect (SSE) in a weak ferromagnetic normal spinel Zinc Ferrite (ZFO). Despite the weak ferromagnetic behavior, the measurements of the SSE in ZFO show a thermoelectric voltage response comparable with the reported values for other ferromagnetic materials. Our results suggest that SSE might possibly originate from the surface magnetization of the ZFO.

  3. Few body hypernuclear systems: Weak decays

    SciTech Connect

    Dover, C.B.

    1987-01-01

    The experimental and theoretical situation regarding mesonic and non-mesonic decays of light hypernuclei is reviewed. Although some models give reasonable results for pionic decays as well as the total weak decay rate, no existing approach explains, even qualitatively, the observed spin-isospin dependence of ..lambda..N ..-->.. NN non-mesonic weak decays. 31 refs., 2 figs.

  4. Weak-value amplification: state of play

    NASA Astrophysics Data System (ADS)

    Knee, George C.; Combes, Joshua; Ferrie, Christopher; Gauger, Erik M.

    2016-01-01

    Weak values arise in quantum theory when the result of a weak measurement is conditioned on a subsequent strong measurement. The majority of the trials are discarded, leaving only very few successful events. Intriguingly those can display a substantial signal amplification. This raises the question of whether weak values carry potential to improve the performance of quantum sensors, and indeed a number of impressive experimental results suggested this may be the case. By contrast, recent theoretical studies have found the opposite: using weak-values to obtain an amplification generally worsens metrological performance. This survey summarises the implications of those studies, which call for a reappraisal of weak values' utility and for further work to reconcile theory and experiment.

  5. Role of autophagy in COPD skeletal muscle dysfunction.

    PubMed

    Hussain, Sabah N A; Sandri, Marco

    2013-05-01

    Chronic obstructive pulmonary disease (COPD) is a debilitating disease caused by parenchymal damage and irreversible airflow limitation. In addition to lung dysfunction, patients with COPD develop weight loss, malnutrition, poor exercise performance, and skeletal muscle atrophy. The latter has been attributed to an imbalance between muscle protein synthesis and protein degradation. Several reports have confirmed that enhanced protein degradation and atrophy of limb muscles of COPD patient is mediated in part through activation of the ubiquitin-proteasome pathway and that this activation is triggered by enhanced production of reactive oxygen species. Until recently, the importance of the autophagy-lysosome pathway in protein degradation of skeletal muscles has been largely ignored, however, recent evidence suggests that this pathway is actively involved in recycling of cytosolic proteins, organelles, and protein aggregates in normal skeletal muscles. The protective role of autophagy in the regulation of muscle mass has recently been uncovered in mice with muscle-specific suppression of autophagy. These mice develop severe muscle weakness, atrophy, and decreased muscle contractility. No information is yet available about the involvement of the autophagy in the regulation of skeletal muscle mass in COPD patients. Pilot experiments on vastus lateralis muscle samples suggest that the autophagy-lysosome system is induced in COPD patients compared with control subjects. In this review, we summarize recent progress related to molecular structure, regulation, and roles of the autophagy-lysosome pathway in normal and diseased skeletal muscles. We also speculate about regulation and functional importance of this system in skeletal muscle dysfunction in COPD patients.

  6. Muscle Session Summary

    NASA Technical Reports Server (NTRS)

    Baldwin, Kenneth; Feeback, Daniel

    1999-01-01

    Presentations from the assembled group of investigators involved in specific research projeects related to skeletal muscle in space flight can categorized in thematic subtopics: regulation of contractile protein phenotypes, muscle growth and atrophy, muscle structure: injury, recovery,and regeneration, metabolism and fatigue, and motor control and loading factors.

  7. Mechanical ventilation, diaphragm weakness and weaning: A rehabilitation perspective

    PubMed Central

    Martin, A Daniel; Smith, Barbara; Gabrielli, Andrea

    2013-01-01

    Most patients are easily liberated from mechanical ventilation (MV) following resolution of respiratory failure and a successful trial of spontaneous breathing, but about 25% of patients experience difficult weaning. MV use leads to cellular changes and weakness, which has been linked to weaning difficulties and has been labeled ventilator induced diaphragm dysfunction (VIDD). Aggravating factors in human studies with prolonged weaning include malnutrition, chronic electrolyte abnormalities, hyperglycemia, excessive resistive and elastic loads, corticosteroids, muscle relaxant exposure, sepsis and compromised cardiac function. Numerous animal studies have investigated the effects of MV on diaphragm function. Virtually all of these studies have concluded that MV use rapidly leads to VIDD and have identified cellular and molecular mechanisms of VIDD. Molecular and functional studies on the effects of MV on the human diaphragm have largely confirmed the animal results and identified potential treatment strategies. Only recently have potential VIDD treatments been tested in humans, including pharmacologic interventions and diaphragm “training”. A limited number of human studies have found that specific diaphragm training can increase respiratory muscle strength in FTW patients and facilitate weaning, but larger, multicenter trials are needed. PMID:23692928

  8. Isolated shoulder weakness as a result of a cortical infarction in the precentral gyrus.

    PubMed

    Entezami, Pouya; Hopper, John A

    2015-01-01

    Since its discovery, our understanding of the primary motor cortex has continued to evolve. The presentations of rare, isolated, motor palsies of small muscle groups have heavily contributed to the characterization of the somatotopic representation of the human body on the cortex. We present a case of localized, left shoulder small muscle group weakness secondary to ischemic cerebral infarction in the primary motor cortex. The patient experienced full recovery over several days. Strokes causing isolated shoulder weakness are rare due to the relatively small area dedicated to shoulder motor function in the precentral gyrus. However, our patient presented with a larger area of infarction than in previously reported cases, demonstrating the large individual variability that may exist within the motor cortex somatotopic map.

  9. Functional characterization of orbicularis oculi and extraocular muscles

    PubMed Central

    Sekulic-Jablanovic, Marijana; Ullrich, Nina D.; Goldblum, David; Palmowski-Wolfe, Anja; Zorzato, Francesco

    2016-01-01

    The orbicularis oculi are the sphincter muscles of the eyelids and are involved in modulating facial expression. They differ from both limb and extraocular muscles (EOMs) in their histology and biochemistry. Weakness of the orbicularis oculi muscles is a feature of neuromuscular disorders affecting the neuromuscular junction, and weakness of facial muscles and ptosis have also been described in patients with mutations in the ryanodine receptor gene. Here, we investigate human orbicularis oculi muscles and find that they are functionally more similar to quadriceps than to EOMs in terms of excitation–contraction coupling components. In particular, they do not express the cardiac isoform of the dihydropyridine receptor, which we find to be highly expressed in EOMs where it is likely responsible for the large depolarization-induced calcium influx. We further show that human orbicularis oculi and EOMs express high levels of utrophin and low levels of dystrophin, whereas quadriceps express dystrophin and low levels of utrophin. The results of this study highlight the notion that myotubes obtained by explanting satellite cells from different muscles are not functionally identical and retain the physiological characteristics of their muscle of origin. Furthermore, our results indicate that sparing of facial and EOMs in patients with Duchenne muscular dystrophy is the result of the higher levels of utrophin expression. PMID:27069119

  10. Predictability of jaw muscle pains from surface electromyograms.

    PubMed

    Christensen, L V; Tran, K T

    1996-04-01

    In seven (88%) of eight healthy subjects, weak to moderate pains were elicited in the masseter muscles through the isometric contractions of maximum voluntary teeth clenching. Integrated surface electromyograms of the right and left masseter muscles were used to quantify the absolute and relative contractile activities of the two muscles. The risk (relative probability) of inducing pain onset in the single masseter muscle generating the larger amount of isometric activity was 2.5 times the risk of eliciting pain onset in the single masseter muscle generating the lesser amount of isometric activity. However, as an aid in the diagnosis of pain onset, the method of masseteric surface electromyography had a false diagnostic ratio of 0.67.

  11. Lower limb muscle impairment in myotonic dystrophy type 1: the need for better guidelines.

    PubMed

    Petitclerc, Émilie; Hébert, Luc J; Desrosiers, Johanne; Gagnon, Cynthia

    2015-04-01

    In myotonic dystrophy type 1 (DM1), leg muscle weakness is a major impairment. There are challenges to obtaining a clear portrait of muscle strength impairment. A systematic literature review was conducted on lower limb strength impairment in late-onset and adult phenotypes to document variables which affect strength measurement. Thirty-two articles were reviewed using the COSMIN guidelines. Only a third of the studies described a reproducible protocol. Only 2 muscle groups have documented reliability for quantitative muscle testing and only 1 total score for manual muscle testing. Variables affecting muscle strength impairment are not described in most studies. This review illustrates the variability in muscle strength assessment in relation to DM1 characteristics and the questionable validity of the results with regard to undocumented methodological properties. There is therefore a clear need to adopt a consensus on the use of a standardized muscle strength assessment protocol.

  12. No clinical or neurophysiological evidence of botulinum toxin diffusion to non-injected muscles in patients with hemifacial spasm.

    PubMed

    Lorenzano, C; Bagnato, S; Gilio, F; Fabbrini, G; Berardelli, A

    2006-04-01

    Botulinum toxin injected into a muscle may diffuse to nearby muscles thus producing unwanted effects. In patients with hemifacial spasm, we evaluated clinically and neurophysiologically, whether botulinum toxin type A (BoNT-A) diffuses from the injection site (orbicularis oculi) to untreated muscles (orbicularis oris from the affected side and orbicularis oculi and oris from the unaffected side). We studied 38 patients with idiopathic hemifacial spasm. Botulinum toxin was injected into the affected orbicularis oculi muscle alone (at 3 standardized sites) at a clinically effective dose. Patients were studied before (T0) and 3-4 weeks after treatment (T1). We evaluated the clinical effects of botulinum toxin and muscle strength in the affected and unaffected muscles. We also assessed the peak-to-peak amplitude compound muscle action potential (CMAP) recorded from the orbicularis oculi and orbicularis oris muscles on both sides after supramaximal electrical stimulation of the facial nerve at the stylomastoid foramen. In all patients, botulinum toxin treatment reduced muscle spasms in the injected orbicularis oculi muscle and induced no muscle weakness in the other facial muscles. The CMAP amplitude significantly decreased in the injected orbicularis oculi muscle, but remained unchanged in the other facial muscles (orbicularis oris muscle on the affected side and contra-lateral unaffected muscles). In conclusion, in patients with hemifacial spasm, botulinum toxin, at a clinically effective dose, induces no clinical signs of diffusion and does not reduce the CMAP size in the nearby untreated orbicularis oris or contralateral facial muscles.

  13. Collagen VI deficiency reduces muscle pathology, but does not improve muscle function, in the γ-sarcoglycan-null mouse

    PubMed Central

    de Greef, Jessica C.; Hamlyn, Rebecca; Jensen, Braden S.; O'Campo Landa, Raul; Levy, Jennifer R.; Kobuke, Kazuhiro; Campbell, Kevin P.

    2016-01-01

    Muscular dystrophy is characterized by progressive skeletal muscle weakness and dystrophic muscle exhibits degeneration and regeneration of muscle cells, inflammation and fibrosis. Skeletal muscle fibrosis is an excessive deposition of components of the extracellular matrix including an accumulation of Collagen VI. We hypothesized that a reduction of Collagen VI in a muscular dystrophy model that presents with fibrosis would result in reduced muscle pathology and improved muscle function. To test this hypothesis, we crossed γ-sarcoglycan-null mice, a model of limb-girdle muscular dystrophy type 2C, with a Col6a2-deficient mouse model. We found that the resulting γ-sarcoglycan-null/Col6a2Δex5 mice indeed exhibit reduced muscle pathology compared with γ-sarcoglycan-null mice. Specifically, fewer muscle fibers are degenerating, fiber size varies less, Evans blue dye uptake is reduced and serum creatine kinase levels are lower. Surprisingly, in spite of this reduction in muscle pathology, muscle function is not significantly improved. In fact, grip strength and maximum isometric tetanic force are even lower in γ-sarcoglycan-null/Col6a2Δex5 mice than in γ-sarcoglycan-null mice. In conclusion, our results reveal that Collagen VI-mediated fibrosis contributes to skeletal muscle pathology in γ-sarcoglycan-null mice. Importantly, however, our data also demonstrate that a reduction in skeletal muscle pathology does not necessarily lead to an improvement of skeletal muscle function, and this should be considered in future translational studies. PMID:26908621

  14. Muscle formation during embryogenesis of the polychaete Ophryotrocha diadema (Dorvilleidae) – new insights into annelid muscle patterns

    PubMed Central

    Bergter, Annette; Brubacher, John L; Paululat, Achim

    2008-01-01

    Background The standard textbook information that annelid musculature consists of oligochaete-like outer circular and inner longitudinal muscle-layers has recently been called into question by observations of a variety of complex muscle systems in numerous polychaete taxa. To clarify the ancestral muscle arrangement in this taxon, we compared myogenetic patterns during embryogenesis of Ophryotrocha diadema with available data on oligochaete and polychaete myogenesis. This work addresses the conflicting views on the ground pattern of annelids, and adds to our knowledge of the evolution of lophotrochozoan taxa. Results Somatic musculature in Ophryotrocha diadema can be classified into the trunk, prostomial/peristomial, and parapodial muscle complexes. The trunk muscles comprise strong bilateral pairs of distinct dorsal and ventral longitudinal strands. The latter are the first to differentiate during myogenesis. They originate within the peristomium and grow posteriorly through the continuous addition of myocytes. Later, the longitudinal muscles also expand anteriorly and form a complex arrangement of prostomial muscles. Four embryonic parapodia differentiate in an anterior-to-posterior progression, significantly contributing to the somatic musculature. Several diagonal and transverse muscles are present dorsally. Some of the latter are situated external to the longitudinal muscles, which implies they are homologous to the circular muscles of oligochaetes. These circular fibers are only weakly developed, and do not appear to form complete muscle circles. Conclusion Comparison of embryonic muscle patterns showed distinct similarities between myogenetic processes in Ophryotrocha diadema and those of oligochaete species, which allows us to relate the diverse adult muscle arrangements of these annelid taxa to each other. These findings provide significant clues for the interpretation of evolutionary changes in annelid musculature. PMID:18171469

  15. Electromyography of the pubococcygeus muscles in patients with obstructed defaecation.

    PubMed

    Lubowski, D Z; King, D W; Finlay, I G

    1992-12-01

    The function of the pubococcygeus muscles during defaecation straining was compared in 10 women with obstructed defaecation and 12 age-matched control subjects. Video-proctography in each patient showed failure to evacuate the rectum and sagging of the pelvic floor during attempted defaecation. Trans-perineal concentric needle electromyography in the puborectalis muscle and transvaginal electromyography in the pubococcygeus muscle was carried out during defaecation straining and during attempted rectal balloon expulsion. Contraction of the pubococcygeus muscle was observed in 10 of the 12 control subjects and in 2 of the 10 patients with obstructed defaecation (P < 0.005). Virtually equal proportions of subjects in each group showed relaxation or contraction of the puborectalis muscle during straining. There was significant perineal descent on straining in the patient group (P = 0.005). This group of patients with obstructed defaecation showed failure of the pubococcygeus muscles to contract, perhaps due to neuropathic weakness of the muscles. The puborectalis muscle did not cause obstructed defaecation in these patients, and the concept of "paradoxical" contraction of this muscle is questioned.

  16. Exercise and nutritional interventions for improving aging muscle health.

    PubMed

    Forbes, Scott C; Little, Jonathan P; Candow, Darren G

    2012-08-01

    Skeletal muscle mass declines with age (i.e., sarcopenia) resulting in muscle weakness and functional limitations. Sarcopenia has been associated with physiological changes in muscle morphology, protein and hormonal kinetics, insulin resistance, inflammation, and oxidative stress. The purpose of this review is to highlight how exercise and nutritional intervention strategies may benefit aging muscle. It is well known that resistance exercise training increases muscle strength and size and evidence also suggests that resistance training can increase mitochondrial content and decrease oxidative stress in older adults. Recent findings suggest that fast-velocity resistance exercise may be an effective intervention for older adults to enhance muscle power and functional capacity. Aerobic exercise training may also benefit aging skeletal muscle by enhancing mitochondrial bioenergetics, improving insulin sensitivity, and/or decreasing oxidative stress. In addition to exercise, creatine monohydrate, milk-based proteins, and essential fatty acids all have biological effects which could enhance some of the physiological adaptations from exercise training in older adults. Additional research is needed to determine whether skeletal muscle adaptations to increased activity in older adults are further enhanced with effective nutritional interventions and whether this is due to enhanced muscle protein synthesis, improved mitochondrial function, and/or a reduced inflammatory response.

  17. Satellite cells from dystrophic muscle retain regenerative capacity.

    PubMed

    Boldrin, Luisa; Zammit, Peter S; Morgan, Jennifer E

    2015-01-01

    Duchenne muscular dystrophy is an inherited disorder that is characterized by progressive skeletal muscle weakness and wasting, with a failure of muscle maintenance/repair mediated by satellite cells (muscle stem cells). The function of skeletal muscle stem cells resident in dystrophic muscle may be perturbed by being in an increasing pathogenic environment, coupled with constant demands for repairing muscle. To investigate the contribution of satellite cell exhaustion to this process, we tested the functionality of satellite cells isolated from the mdx mouse model of Duchenne muscular dystrophy. We found that satellite cells derived from young mdx mice contributed efficiently to muscle regeneration within our in vivo mouse model. To then test the effects of long-term residence in a dystrophic environment, satellite cells were isolated from aged mdx muscle. Surprisingly, they were as functional as those derived from young or aged wild type donors. Removing satellite cells from a dystrophic milieu reveals that their regenerative capacity remains both intact and similar to satellite cells derived from healthy muscle, indicating that the host environment is critical for controlling satellite cell function.

  18. Caveolin-1, caveolin-3 and VEGF expression in the masticatory muscles of mdx mice.

    PubMed

    Kunert-Keil, Christiane; Gredes, Tomasz; Lucke, Silke; Morgenstern, Sven; Mielczarek, Agnieszka; Sporniak-Tutak, Katarzyna; Gedrange, Tomasz; Spassov, Alexander

    2011-01-01

    Duchenne muscular dystrophy (DMD) and murine X-linked muscular dystrophy (mdx), its murine model, are characterized by muscle damage and muscle weakness associated with inflammation and new vessel formation. Caveolins, dystrophin-associated proteins, are involved in the pathogenesis of DMD, because increased numbers of caveolae are found in DMD and mdx hindlimb muscles. Caveolae influence angiogenesis due to their content of vascular endothelial growth factor (VEGF) receptors. Orofacial muscles in mdx mice undergo muscle necrosis followed by muscle regeneration. To ascertain the role of caveolins and VEGF in the pathogenesis of dystrophic masticatory muscles, we examined the expression of caveolin-1 (cav-1), caveolin-3 (cav-3) and VEGF in control and mdx mice. In mdx masticatory muscles, no changes in transcript and protein levels of VEGF were found, whereas cav-1 and cav-3 expression was increased. Using immunohistochemistry, a strong sarcolemmal staining of caveolin-3 in regenerated muscle fibers was found. Furthermore, immunohistochemistry with the caveolin-1 antibody showed an increase in the amount of blood vessels in areas with regenerating muscle fibers. Dystrophic masticatory muscles showed changes comparable to those of hindlimb muscles in the expression of cav-1 and cav-3. The angiogenesis seems to be unaffected in the jaw muscles of mdx mice. We speculate that the increased caveolin expression could cause extensive and efficient muscle regeneration.

  19. Spectrum of Mathematical Weaknesses: Related Neuropsychological Correlates.

    PubMed

    Perna, Robert; Loughan, Ashlee R; Le, Jessica; Hertza, Jeremy; Cohen, Morris J

    2015-01-01

    Math disorders have been recognized for as long as language disorders yet have received far less research. Mathematics is a complex construct and its development may be dependent on multiple cognitive abilities. Several studies have shown that short-term memory, working memory, visuospatial skills, processing speed, and various language skills relate to and may facilitate math development and performance. The hypotheses explored in this research were that children who performed worse on math achievement than on Full-Scale IQ would exhibit weaknesses in executive functions, memory, and visuoperceptual skills. Participants included 436 children (27% girls, 73% boys; age range = 5-17 years, M(age) = 9.45 years) who were referred for neuropsychological evaluations due to academic and/or behavioral problems. This article specifically focuses on the spectrum of math weakness rather than clinical disability, which has yet to be investigated in the literature. Results suggest that children with relative weakness to impairments in math were significantly more likely to have cognitive weaknesses to impairments on neuropsychological variables, as compared with children without math weaknesses. Specifically, the math-weak children exhibit a weakness to impairment on measures involving attention, language, visuoperceptual skills, memory, reading, and spelling. Overall, our results suggest that math development is multifaceted.

  20. Oxidative Metabolism in Muscle

    NASA Astrophysics Data System (ADS)

    Ferrari, M.; Binzoni, T.; Quaresima, V.

    1997-06-01

    Oxidative metabolism is the dominant source of energy for skeletal muscle. Near-infrared spectroscopy allows the non-invasive measurement of local oxygenation, blood flow and oxygen consumption. Although several muscle studies have been made using various near-infrared optical techniques, it is still difficult to interpret the local muscle metabolism properly. The main findings of near-infrared spectroscopy muscle studies in human physiology and clinical medicine are summarized. The advantages and problems of near-infrared spectroscopy measurements, in resting and exercising skeletal muscles studies, are discussed through some representative examples.

  1. Muscle restricted vasculitis causing dropped head syndrome: a case report and review of the literature.

    PubMed

    Nielsen, Amy Almaraz; Smith, Benn E; Engel, Andrew G; Bosch, Erich Peter

    2012-03-01

    A 52-year-old man presented with a severe head drop and proximal extremity weakness. Magnetic resonance imaging of the cervical spine showed T2 hyperintensity in cervical paraspinal muscles. Electrodiagnostic studies revealed an axial myopathy isolated to paraspinal muscles. A splenius capitis muscle biopsy confirmed an acute myopathy associated with nonsystemic vasculitis. The patient improved on steroids, intravenous immunoglobulin, and monthly pulse doses of cyclophosphamide. Our case emphasizes that a subgroup of patients with dropped head syndrome have treatable conditions.

  2. Subcellular distribution of potassium in striated muscles

    SciTech Connect

    Edelmann, L.

    1984-01-01

    Microanalytical experiments have been performed to answer the question whether the main cellular cation, K+, follows the water distribution in the striated muscle cell or whether K+ follows the distribution of negative fixed charges (beta- and gamma-carboxyl groups of aspartic and glutamic acid residues). Subcellular localization of K and/or of the K surrogates Rb, Cs, and Tl has been investigated by the following methods: Chemical precipitation of K with tetraphenylborate. Autoradiography of alkali-metals and Tl in air-dried and frozen-hydrated preparations. TEM visualization of electron dense Cs and Tl in sections of freeze-dried and plastic embedded muscle. X-ray microanalysis of air-dried myofibrils and muscle cryosections. The experiments consistently show that K, Rb, Cs, and Tl do not follow the water distribution but are mainly accumulated in the A band, especially in the marginal regions, and at Z lines. The same sites preferentially accumulate Cs or uranyl cations when sections of freeze-dried, embedded muscle are exposed to these electron microscopic stains. It is concluded that the detected uneven distribution of K, Rb, Cs, and Tl in muscle is neither a freeze-drying artifact nor an embedding artifact and may result from a weak ion binding to the beta- and gamma-carboxyl groups of cellular proteins.

  3. Effects of shakuyakukanzoto and its absorbed components on twitch contractions induced by physiological Ca2+ release in rat skeletal muscle.

    PubMed

    Kaifuchi, Noriko; Omiya, Yuji; Kushida, Hirotaka; Fukutake, Miwako; Nishimura, Hiroaki; Kase, Yoshio

    2015-07-01

    Shakuyakukanzoto (SKT) is a kampo medicine composed of equal proportions of Glycyrrhizae radix (G. radix) and Paeoniae radix (P. radix). A double-blind study reported that SKT significantly ameliorated painful muscle cramp in cirrhosis patients without the typical severe side effects of muscle weakness and central nervous system (CNS) depression. Previous basic studies reported that SKT and its active components induced relaxation by a direct action on skeletal muscle and that SKT did not depress CNS functions; however, why SKT has a lower incidence of muscle weakness remains unknown. In the present study, we investigated which components are absorbed into the blood of rats after a single oral administration of SKT to identify the active components of SKT. We also investigated the effects of SKT and its components on the twitch contraction induced by physiological Ca(2+) release. Our study demonstrated that SKT and five G. radix isolates, which are responsible for the antispasmodic effect of SKT, did not inhibit the twitch contraction in contrast to dantrolene sodium, a direct-acting peripheral muscle relaxant, indicating that the mechanisms of muscle contraction of SKT and dantrolene in skeletal muscle differ. These findings suggest that SKT does not reduce the contractile force in skeletal muscle under physiological conditions, i.e., SKT may have a low risk of causing muscle weakness in clinical use. Considering that most muscle relaxants and anticonvulsants cause various harmful side effects such as weakness and CNS depression, SKT appears to have a benign safety profile.

  4. Quantum correlation cost of the weak measurement

    SciTech Connect

    Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui

    2014-12-15

    Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be ‘extracted’ not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

  5. Muscle-directed gene therapy for phenylketonuria (PKU): Development of transgenic mice with muscle-specific phenylalanine hydroxylase expression

    SciTech Connect

    Harding, C.O.; Messing, A.; Wolff, J.A.

    1994-09-01

    Phenylketonuria (PKU) is an attractive target for gene therapy because of shortcomings in current therapy including lifelong commitment to a difficult and expensive diet, persistent mild cognitive deficits in some children despite adequate dietary therapy, and maternal PKU syndrome. Phenylalanine hydroxylase (PAH) is normally expressed only in liver, but we propose to treat PKU by introducing the gene for PAH into muscle. In order to evaluate both the safety and efficacy of this approach, we have a developed a trangenic mouse which expresses PAH in both cardiac and skeletal muscle. The transgene includes promoter and enhancer sequences from the mouse muscle creatine kinase (MCK) gene fused to the mouse liver PAH cDNA. Mice which have inherited the transgene are healthy, active, and do not exhibit any signs of muscle weakness or wasting. Ectopic PAH expression in muscle is not detrimental to the health, neurologic function, or reproduction of the mice. Pah{sup enu2} hyperphenylalaninemic mice, a model of human PAH deficiency, bred to carry the transgene have substantial PAH expression in cardiac and skeletal muscle but none in liver. Muscle PAH expression alone does not complement the hyperphenylalaninemic phenotype of Pah{sup enu2} mice. However, administration of reduced tetrahydrobiopterin to transgenic Pah{sup enu2} mice is associated with a 25% mean decrease in serum phenylalanine levels. We predict that ectopic expression of PAH in muscle along with adequate muscle supplies of reduced biopterin cofactor will decrease hyperphenylalaninemia in PKU.

  6. What is the proper approach to liberating the weak from mechanical ventilation?

    PubMed

    Brochard, Laurent; Thille, Arnaud W

    2009-10-01

    The general issue of weaning can be viewed as composed of three different groups of patients. First, simple or easy weaning, represents 60% to 70% of patients whose first trial of spontaneous breathing is successful. The main objective of the weaning process is to detect weaning readiness as early as possible, which is best achieved using a systematic approach. The percentage of patients in this group in a given intensive care unit represents the pretest probability of weaning. A second group is made of patients who experience failure of the first spontaneous breathing trial and in whom up to 7 days from the first trial may be required to achieve weaning. This group represents 20% to 25% of patients who undergo weaning from mechanical ventilation. Muscle weakness contributes to the prolongation of weaning in many of these patients. The last group is made of patients who are characterized by a prolonged or very difficult weaning process (about 5% to 15% of patients undergoing weaning). Muscle weakness is likely to be a major contributing factor. Early use of spontaneous breathing, well-controlled use of sedation, and early mobilization may help in reducing muscle weakness and hasten the weaning process. The postextubation period may be particularly at risk in these patients. More research is needed to guide clinicians regarding the best ventilatory management.

  7. Rejuvenation of the muscle stem cell population restores strength to injured aged muscles.

    PubMed

    Cosgrove, Benjamin D; Gilbert, Penney M; Porpiglia, Ermelinda; Mourkioti, Foteini; Lee, Steven P; Corbel, Stephane Y; Llewellyn, Michael E; Delp, Scott L; Blau, Helen M

    2014-03-01

    The elderly often suffer from progressive muscle weakness and regenerative failure. We demonstrate that muscle regeneration is impaired with aging owing in part to a cell-autonomous functional decline in skeletal muscle stem cells (MuSCs). Two-thirds of MuSCs from aged mice are intrinsically defective relative to MuSCs from young mice, with reduced capacity to repair myofibers and repopulate the stem cell reservoir in vivo following transplantation. This deficiency is correlated with a higher incidence of cells that express senescence markers and is due to elevated activity of the p38α and p38β mitogen-activated kinase pathway. We show that these limitations cannot be overcome by transplantation into the microenvironment of young recipient muscles. In contrast, subjecting the MuSC population from aged mice to transient inhibition of p38α and p38β in conjunction with culture on soft hydrogel substrates rapidly expands the residual functional MuSC population from aged mice, rejuvenating its potential for regeneration and serial transplantation as well as strengthening of damaged muscles of aged mice. These findings reveal a synergy between biophysical and biochemical cues that provides a paradigm for a localized autologous muscle stem cell therapy for the elderly.

  8. Rejuvenation of the aged muscle stem cell population restores strength to injured aged muscles

    PubMed Central

    Cosgrove, Benjamin D.; Gilbert, Penney M.; Porpiglia, Ermelinda; Mourkioti, Foteini; Lee, Steven P.; Corbel, Stephane Y.; Llewellyn, Michael E.; Delp, Scott L.; Blau, Helen M.

    2014-01-01

    The aged suffer from progressive muscle weakness and regenerative failure. We demonstrate that muscle regeneration is impaired with aging due in part to a cell-autonomous functional decline in skeletal muscle stem cells (MuSCs). Two-thirds of aged MuSCs are intrinsically defective relative to young MuSCs, with reduced capacity to repair myofibers and repopulate the stem cell reservoir in vivo following transplantation due to a higher incidence of cells that express senescence markers and that have elevated p38α/β MAPK activity. We show that these limitations cannot be overcome by transplantation into the microenvironment of young recipient muscles. In contrast, subjecting the aged MuSC population to transient inhibition of p38α/β in conjunction with culture on soft hydrogel substrates rapidly expands the residual functional aged MuSC population, rejuvenating its potential for regeneration, serial transplantation, and strengthening damaged muscles of aged mice. These findings reveal a synergy between biophysical and biochemical cues that provides a paradigm for a localized autologous muscle stem cell therapy in aged individuals. PMID:24531378

  9. Reliability of a novel neurostimulation method to study involuntary muscle phenomena.

    PubMed

    Minetto, Marco Alessandro; Botter, Alberto; Ravenni, Roberta; Merletti, Roberto; De Grandis, Domenico

    2008-01-01

    Experimental methods involving painful electrical stimulation of a peripheral nerve showed the existence of a minimum stimulation frequency capable of inducing cramp, termed "threshold frequency" (TF). Our aim was to test an alternative method to induce fasciculations and cramps electrically. Two daily sessions of electrical stimulation of the abductor hallucis muscle were performed in 19 volunteers on 3 days: stimulation trains of 150 monophasic square pulses (duration 152 micros) of increasing frequency (current intensity 30% higher than maximal; frequency of the first trial, 4 pps; recovery between trials, 1 min) were delivered to the main muscle motor point until a cramp developed. Once a cramp was induced the protocol was repeated after 30 min. To verify by electromyography that cramp occurred, a surface electrode array was placed between the motor point and the distal tendon. Ambient and skin temperature were kept constant in all sessions. Fasciculations and cramps were elicited in all subjects. We observed the following median (interquartile range) values of TF: day 1 (session 1), 13 (6) pps; day 1 (session 2), 16 (4) pps; day 2 (session 1), 16 (6) pps; day 2 (session 2), 18 (6) pps; day 3 (session 1), 17 (4) pps; day 3 (session 2), 18 (8) pps. TF intersession intraclass correlation coefficients were 0.82, 0.92, and 0.90 for days 1, 2, and 3, respectively. TF interday intraclass correlation coefficient was 0.85. The absence of pain due to the stimulation and the demonstration of TF reliability support the use of our method for the study of involuntary muscle phenomena.

  10. The reaction time of single motor units in the human muscle.

    PubMed

    Kosarov, D

    1979-01-01

    The reaction time for activating a single motor unit (MU) with one impulse only, upon visual and auditory feed-back was studied in six healthy subjects. Use was made of MUs from m.abductor dig.V. The subjects were trained until they achieved more than 50% correct performances. One hundred responses were investigated in each series of experiments. The stimulus to which the subjects should have to respond was a beam presented on the screen of a "Disa" 14A30 electromyograph. Simultaneously with the beam the stimulator switched on a digital chronometer which was switched off by the MU impulse. Another two series of experiments were also performed in which the subjects responded with a train of impulses from the MU or with a burst of impulses from the whole muscle. It was been found that the mean reaction time for one impulse from one MU is longer (300 ms), for a train of impulses from one MU it is shorter (260 ms) and for a burst of impulses it is the shortest (200 ms). The histogram of distribution in the first series of experiments deviated from the normal distribution and showed a second maximum at 120 ms after the first maximum. The latter did not differ from the maxima in the distributions of the second and third series of experiments--about 200 ms after the visual stimulus presentation. The difference in the mean reaction time for the three series of experiments is due to the differences in the motor tasks connected with different velocity of increase of the muscle tension, as increasing velocity decreases the MU recruitment thresholds. The separate MUs might be activated in the same short periods as the whole muscle but they showed some specificities in the time distribution of the responses which might be due to some discrete mechanisms of the motor control system.

  11. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups.

    PubMed

    Randolph, Matthew E; Pavlath, Grace K

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease.

  12. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    PubMed Central

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  13. Sodium in weak G-band giants

    NASA Technical Reports Server (NTRS)

    Drake, Jeremy J.; Lambert, David L.

    1994-01-01

    Sodium abundances have been determined for eight weak G-band giants whose atmospheres are greatly enriched with products of the CN-cycling H-burning reactions. Systematic errors are minimized by comparing the weak G-band giants to a sample of similar but normal giants. If, further, Ca is selected as a reference element, model atmosphere-related errors should largely be removed. For the weak-G-band stars (Na/Ca) = 0.16 +/- 0.01, which is just possibly greater than the result (Na/Ca) = 0.10 /- 0.03 from the normal giants. This result demonstrates that the atmospheres of the weak G-band giants are not seriously contaminated with products of ON cycling.

  14. Reversing entanglement change by a weak measurement

    SciTech Connect

    Sun Qingqing; Zubairy, M. Suhail; Al-Amri, M.; Davidovich, Luiz

    2010-11-15

    Entanglement of a system changes due to interactions with the environment. A typical type of interaction is amplitude damping. If we add a detector to monitor the environment and only select the no-damping outcome, this amplitude damping is modified into a weak measurement. Here we show that the entanglement change of a two-qubit state due to amplitude damping or weak measurement can be probabilistically reversed. For the amplitude-damping case, the entanglement partially recovers under most conditions. For the weak-measurement case, the recovery of the initial entangled state is exact. The reversal procedure involves another weak measurement, preceded and followed by bit flips applied to both qubits. We propose a linear optics scheme for the experimental demonstration of these procedures.

  15. Gait propulsion in patients with facioscapulohumeral muscular dystrophy and ankle plantarflexor weakness.

    PubMed

    Rijken, N H M; van Engelen, B G M; de Rooy, J W J; Weerdesteyn, V; Geurts, A C H

    2015-02-01

    Facioscapulohumeral muscular dystrophy is a slowly progressive hereditary disorder resulting in fatty infiltration of eventually most skeletal muscles. Weakness of trunk and leg muscles causes problems with postural balance and gait, and is associated with an increased fall risk. Although drop foot and related tripping are common problems in FSHD, gait impairments are poorly documented. The effect of ankle plantarflexor involvement on gait propulsion has never been addressed. In addition to ankle plantarflexion, gait propulsion is generated through hip flexion and hip extension. Compensatory shifts between these propulsion sources occur when specific muscles are affected. Such a shift may be expected in patients with FSHD since the calves may show early fatty infiltration, whereas iliopsoas and gluteus maximus muscles are often spared for a longer time. In the current study, magnetic resonance imaging was used to assess the percentage of unaffected calf, iliopsoas and gluteus maximus muscles. Joint powers were analyzed in 10 patients with FSHD at comfortable and maximum walking speed to determine the contribution of ankle plantarflexor, hip flexor and hip extensor power to propulsion. Associations between muscle morphology, power generation and gait speed were assessed. Based on multivariate regression analysis, ankle plantarflexor power was the only factor that uniquely contributed to the explained variance of comfortable (R(2)=80%) and maximum (R(2)=86%) walking speed. Although the iliopsoas muscles were largely unaffected, they appeared to be sub-maximally recruited. This submaximal recruitment may be related to poor trunk stability, resulting in a disproportionate effect of calf muscle affliction on gait speed in patients with FSHD.

  16. Elastic scattering with weakly bound projectiles

    SciTech Connect

    Figueira, J. M.; Abriola, D.; Arazi, A.; Capurro, O. A.; Marti, G. V.; Martinez Heinmann, D.; Pacheco, A. J.; Testoni, J. E.; Barbara, E. de; Fernandez Niello, J. O.; Padron, I.; Gomes, P. R. S.; Lubian, J.

    2007-02-12

    Possible effects of the break-up channel on the elastic scattering threshold anomaly has been investigated. We used the weakly bound 6,7Li nuclei, which is known to undergo break-up, as projectiles in order to study the elastic scattering on a 27Al target. In this contribution we present preliminary results of these experiments, which were analyzed in terms of the Optical Model and compared with other elastic scattering data using weakly bound nuclei as projectile.

  17. Laryngeal stridor in multiple system atrophy: Clinicopathological features and causal hypotheses.

    PubMed

    Ozawa, Tetsutaro; Sekiya, Kanako; Aizawa, Naotaka; Terajima, Kenshi; Nishizawa, Masatoyo

    2016-02-15

    Laryngeal stridor is recognized as a characteristic clinical manifestation in patients with multiple system atrophy (MSA). However, the pathogenic mechanisms underlying this symptom are controversial. Neurogenic atrophy of the posterior cricoarytenoid muscle has been identified in cases of MSA, suggesting that laryngeal abductor weakness contributes to laryngeal stridor. However, dystonia in the laryngeal adductor muscles has also been reported to cause laryngeal stridor. Depletion of serotonergic neurons in the medullary raphe nuclei, which exert tonic drive to activate the posterior cricoarytenoid muscle, has recently been identified in MSA cases. This adds weight to the possibility that laryngeal abductor weakness underlies laryngeal stridor in MSA. Continuous positive airway pressure therapy is currently used in the treatment of laryngeal stridor, but should be used with caution in patients showing contraindications. Current knowledge of the clinical and neuropathological features of laryngeal stridor is summarized in this paper, and the hypothesized causes and possible therapeutic options for this symptom are discussed.

  18. Muscle injuries: optimising recovery.

    PubMed

    Järvinen, Tero A H; Järvinen, Teppo L N; Kääriäinen, Minna; Aärimaa, Ville; Vaittinen, Samuli; Kalimo, Hannu; Järvinen, Markku

    2007-04-01

    Muscle injuries are one of the most common traumas occurring in sports. Despite their clinical importance, there are only a few clinical studies on the treatment of muscle injuries. Lack of clinical studies is most probably attributable to the fact that there is not only a high heterogeneity in the severity of injuries, but also the injuries take place in different muscles, making it very demanding to carry out clinical trials. Accordingly, the current treatment principles of muscle injuries have either been derived from experimental studies or been tested empirically only. Clinically, first aid for muscle injuries follows the RICE (Rest, Ice, Compression and Elevation) principle. The objective of RICE is to stop the injury-induced bleeding into the muscle tissue and thereby minimise the extent of the injury. Clinical examination should be carried out immediately after the injury and 5-7 days after the initial trauma, at which point the severity of the injury can be assessed more reliably. At that time, a more detailed characterisation of the injury can be made using imaging diagnostic modalities (ultrasound or MRI) if desired. The treatment of injured skeletal muscle should be carried out by immediate immobilisation of the injured muscle (clinically, relative immobility/avoidance of muscle contractions). However, the duration of immobilisation should be limited to a period sufficient to produce a scar of sufficient strength to bear the forces induced by remobilisation without re-rupture and the return to activity (mobilisation) should then be started gradually within the limits of pain. Early return to activity is needed to optimise the regeneration of healing muscle and recovery of the flexibility and strength of the injured skeletal muscle to pre-injury levels. The rehabilitation programme should be built around progressive agility and trunk stabilisation exercises, as these exercises seem to yield better outcome for injured skeletal muscle than programmes based

  19. IL-6 signaling blockade increases inflammation but does not affect muscle function in the mdx mouse

    PubMed Central

    2012-01-01

    Background IL-6 is a pleiotropic cytokine that modulates inflammatory responses and plays critical roles in muscle maintenance and remodeling. In the mouse model (mdx) of Duchenne Muscular Dystrophy, IL-6 and muscle inflammation are elevated, which is believed to contribute to the chronic inflammation and failure of muscle regeneration in DMD. The purpose of the current study was to examine the effect of blocking IL-6 signaling on the muscle phenotype including muscle weakness and pathology in the mdx mouse. Methods A monoclonal antibody against the IL-6 receptor (IL-6r mAb) that blocks local and systemic IL-6 signaling was administered to mdx and BL-10 mice for 5 weeks and muscle function, histology, and inflammation were examined. Results IL-6r mAb treatment increased mdx muscle inflammation including total inflammation score and ICAM-1 positive lumens in muscles. There was no significant improvement in muscle strength nor muscle pathology due to IL-6r mAb treatment in mdx mice. Conclusions These results showed that instead of reducing inflammation, IL-6 signaling blockade for 5 weeks caused an increase in muscle inflammation, with no significant change in indices related to muscle regeneration and muscle function. The results suggest a potential anti-inflammatory instead of the original hypothesized pro-inflammatory role of IL-6 signaling in the mdx mice. PMID:22716658

  20. Evolving concepts on the age-related changes in "muscle quality".

    PubMed

    Russ, David W; Gregg-Cornell, Kimberly; Conaway, Matthew J; Clark, Brian C

    2012-06-01

    The deterioration of skeletal muscle with advancing age has long been anecdotally recognized and has been of scientific interest for more than 150 years. Over the past several decades, the scientific and medical communities have recognized that skeletal muscle dysfunction (e.g., muscle weakness, poor muscle coordination, etc.) is a debilitating and life-threatening condition in the elderly. For example, the age-associated loss of muscle strength is highly associated with both mortality and physical disability. It is well-accepted that voluntary muscle force production is not solely dependent upon muscle size, but rather results from a combination of neurologic and skeletal muscle factors, and that biologic properties of both of these systems are altered with aging. Accordingly, numerous scientists and clinicians have used the term "muscle quality" to describe the relationship between voluntary muscle strength and muscle size. In this review article, we discuss the age-associated changes in the neuromuscular system-starting at the level of the brain and proceeding down to the subcellular level of individual muscle fibers-that are potentially influential in the etiology of dynapenia (age-related loss of muscle strength and power).

  1. Hypophosphatemia promotes lower rates of muscle ATP synthesis

    PubMed Central

    Pesta, Dominik H.; Tsirigotis, Dimitrios N.; Befroy, Douglas E.; Caballero, Daniel; Jurczak, Michael J.; Rahimi, Yasmeen; Cline, Gary W.; Dufour, Sylvie; Birkenfeld, Andreas L.; Rothman, Douglas L.; Carpenter, Thomas O.; Insogna, Karl; Petersen, Kitt Falk; Bergwitz, Clemens; Shulman, Gerald I.

    2016-01-01

    Hypophosphatemia can lead to muscle weakness and respiratory and heart failure, but the mechanism is unknown. To address this question, we noninvasively assessed rates of muscle ATP synthesis in hypophosphatemic mice by using in vivo saturation transfer [31P]-magnetic resonance spectroscopy. By using this approach, we found that basal and insulin-stimulated rates of muscle ATP synthetic flux (VATP) and plasma inorganic phosphate (Pi) were reduced by 50% in mice with diet-induced hypophosphatemia as well as in sodium-dependent Pi transporter solute carrier family 34, member 1 (NaPi2a)-knockout (NaPi2a−/−) mice compared with their wild-type littermate controls. Rates of VATP normalized in both hypophosphatemic groups after restoring plasma Pi concentrations. Furthermore, VATP was directly related to cellular and mitochondrial Pi uptake in L6 and RC13 rodent myocytes and isolated muscle mitochondria. Similar findings were observed in a patient with chronic hypophosphatemia as a result of a mutation in SLC34A3 who had a 50% reduction in both serum Pi content and muscle VATP. After oral Pi repletion and normalization of serum Pi levels, muscle VATP completely normalized in the patient. Taken together, these data support the hypothesis that decreased muscle ATP synthesis, in part, may be caused by low blood Pi concentrations, which may explain some aspects of muscle weakness observed in patients with hypophosphatemia.—Pesta, D. H., Tsirigotis, D. N., Befroy, D. E., Caballero, D., Jurczak, M. J., Rahimi, Y., Cline, G. W., Dufour, S., Birkenfeld, A. L., Rothman, D. L., Carpenter, T. O., Insogna, K., Petersen, K. F., Bergwitz, C., Shulman, G. I. Hypophosphatemia promotes lower rates of muscle ATP synthesis. PMID:27338702

  2. A patient with progressive weakness and cramping of right arm and both legs. Diagnosis: persistent, multifocal, partial conduction blocks (CB) of motor axons outside the common sites of nerve entrapment.

    PubMed

    Burakgazi, Ahmet Z; Kelly, John J

    2010-01-01

    A 44-year-old man presented with a 1-year history of progressive muscle weakness and cramping. Neurophysiology study, along with clinical presentation, was diagnostic. The differential diagnosis, diagnostic testing, treatment, and prognosis of this rare disease are discussed.

  3. Muscle development and obesity

    PubMed Central

    2008-01-01

    The formation of skeletal muscle from the epithelial somites involves a series of events triggered by temporally and spatially discrete signals resulting in the generation of muscle fibers which vary in their contractile and metabolic nature. The fiber type composition of muscles varies between individuals and it has now been found that there are differences in fiber type proportions between lean and obese animals and humans. Amongst the possible causes of obesity, it has been suggested that inappropriate prenatal environments may ‘program’ the fetus and may lead to increased risks for disease in adult life. The characteristics of muscle are both heritable and plastic, giving the tissue some ability to adapt to signals and stimuli both pre and postnatally. Given that muscle is a site of fatty acid oxidation and carbohydrate metabolism and that its development can be changed by prenatal events, it is interesting to examine the possible relationship between muscle development and the risk of obesity. PMID:19279728

  4. Enhancing QKD security with weak measurements

    NASA Astrophysics Data System (ADS)

    Farinholt, Jacob M.; Troupe, James E.

    2016-10-01

    Publisher's Note: This paper, originally published on 10/24/2016, was replaced with a corrected/revised version on 11/8/2016. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance. In the late 1980s, Aharonov and colleagues developed the notion of a weak measurement of a quantum observable that does not appreciably disturb the system.1, 2 The measurement results are conditioned on both the pre-selected and post-selected state of the quantum system. While any one measurement reveals very little information, by making the same measurement on a large ensemble of identically prepared pre- and post-selected (PPS) states and averaging the results, one may obtain what is known as the weak value of the observable with respect to that PPS ensemble. Recently, weak measurements have been proposed as a method of assessing the security of QKD in the well-known BB84 protocol.3 This weak value augmented QKD protocol (WV-QKD) works by additionally requiring the receiver, Bob, to make a weak measurement of a particular observable prior to his strong measurement. For the subset of measurement results in which Alice and Bob's measurement bases do not agree, the weak measurement results can be used to detect any attempt by an eavesdropper, Eve, to correlate her measurement results with Bob's. Furthermore, the well-known detector blinding attacks, which are known to perfectly correlate Eve's results with Bob's without being caught by conventional BB84 implementations, actually make the eavesdropper more visible in the new WV-QKD protocol. In this paper, we will introduce the WV-QKD protocol and discuss its generalization to the 6-state single qubit protocol. We will discuss the types of weak measurements that are optimal for this protocol, and compare the predicted performance of the 6- and 4-state WV-QKD protocols.

  5. Accurate and representative decoding of the neural drive to muscles in humans with multi-channel intramuscular thin-film electrodes.

    PubMed

    Muceli, Silvia; Poppendieck, Wigand; Negro, Francesco; Yoshida, Ken; Hoffmann, Klaus P; Butler, Jane E; Gandevia, Simon C; Farina, Dario

    2015-09-01

    Intramuscular electrodes developed over the past 80 years can record the concurrent activity of only a few motor units active during a muscle contraction. We designed, produced and tested a novel multi-channel intramuscular wire electrode that allows in vivo concurrent recordings of a substantially greater number of motor units than with conventional methods. The electrode has been extensively tested in deep and superficial human muscles. The performed tests indicate the applicability of the proposed technology in a variety of conditions. The electrode represents an important novel technology that opens new avenues in the study of the neural control of muscles in humans. We describe the design, fabrication and testing of a novel multi-channel thin-film electrode for detection of the output of motoneurones in vivo and in humans, through muscle signals. The structure includes a linear array of 16 detection sites that can sample intramuscular electromyographic activity from the entire muscle cross-section. The structure was tested in two superficial muscles (the abductor digiti minimi (ADM) and the tibialis anterior (TA)) and a deep muscle (the genioglossus (GG)) during contractions at various forces. Moreover, surface electromyogram (EMG) signals were concurrently detected from the TA muscle with a grid of 64 electrodes. Surface and intramuscular signals were decomposed into the constituent motor unit (MU) action potential trains. With the intramuscular electrode, up to 31 MUs were identified from the ADM muscle during an isometric contraction at 15% of the maximal force (MVC) and 50 MUs were identified for a 30% MVC contraction of TA. The new electrode detects different sources from a surface EMG system, as only one MU spike train was found to be common in the decomposition of the intramuscular and surface signals acquired from the TA. The system also allowed access to the GG muscle, which cannot be analysed with surface EMG, with successful identification of MU

  6. Muscle progenitor cell regenerative capacity in the torn rotator cuff.

    PubMed

    Meyer, Gretchen A; Farris, Ashley L; Sato, Eugene; Gibbons, Michael; Lane, John G; Ward, Samuel R; Engler, Adam J

    2015-03-01

    Chronic rotator cuff (RC) tears affect a large portion of the population and result in substantial upper extremity impairment, shoulder weakness, pain, and limited range of motion. Regardless of surgical or conservative treatment, persistent atrophic muscle changes limit functional restoration and may contribute to surgical failure. We hypothesized that deficits in the skeletal muscle progenitor (SMP) cell pool could contribute to poor muscle recovery following tendon repair. Biopsies were obtained from patients undergoing arthroscopic RC surgery. The SMP population was quantified, isolated, and assayed in culture for its ability to proliferate and fuse in vitro and in vivo. The SMP population was larger in muscles from cuffs with partial tears compared with no tears or full thickness tears. However, SMPs from muscles in the partial tear group also exhibited reduced proliferative ability. Cells from all cuff states were able to fuse robustly in culture and engraft when injected into injured mouse muscle, suggesting that when given the correct signals, SMPs are capable of contributing to muscle hypertrophy and regeneration regardless of tear severity. The fact that this does not appear to happen in vivo helps focus future therapeutic targets for promoting muscle recovery following rotator cuff repairs and may help improve clinical outcomes.

  7. Muscle Changes in Aging

    PubMed Central

    Siparsky, Patrick N.; Kirkendall, Donald T.; Garrett, William E.

    2014-01-01

    Muscle physiology in the aging athlete is complex. Sarcopenia, the age-related decrease in lean muscle mass, can alter activity level and affect quality of life. This review addresses the microscopic and macroscopic changes in muscle with age, recognizes contributing factors including nutrition and changes in hormone levels, and identifies potential pharmacologic agents in clinical trial that may aid in the battle of this complex, costly, and disabling problem. Level of Evidence: Level 5. PMID:24427440

  8. Impact of Spinal Manipulation on Cortical Drive to Upper and Lower Limb Muscles

    PubMed Central

    Haavik, Heidi; Niazi, Imran Khan; Jochumsen, Mads; Sherwin, Diane; Flavel, Stanley; Türker, Kemal S.

    2016-01-01

    This study investigates whether spinal manipulation leads to changes in motor control by measuring the recruitment pattern of motor units in both an upper and lower limb muscle and to see whether such changes may at least in part occur at the cortical level by recording movement related cortical potential (MRCP) amplitudes. In experiment one, transcranial magnetic stimulation input–output (TMS I/O) curves for an upper limb muscle (abductor pollicus brevis; APB) were recorded, along with F waves before and after either spinal manipulation or a control intervention for the same subjects on two different days. During two separate days, lower limb TMS I/O curves and MRCPs were recorded from tibialis anterior muscle (TA) pre and post spinal manipulation. Dependent measures were compared with repeated measures analysis of variance, with p set at 0.05. Spinal manipulation resulted in a 54.5% ± 93.1% increase in maximum motor evoked potential (MEPmax) for APB and a 44.6% ± 69.6% increase in MEPmax for TA. For the MRCP data following spinal manipulation there were significant difference for amplitude of early bereitschafts-potential (EBP), late bereitschafts potential (LBP) and also for peak negativity (PN). The results of this study show that spinal manipulation leads to changes in cortical excitability, as measured by significantly larger MEPmax for TMS induced input–output curves for both an upper and lower limb muscle, and with larger amplitudes of MRCP component post manipulation. No changes in spinal measures (i.e., F wave amplitudes or persistence) were observed, and no changes were shown following the control condition. These results are consistent with previous findings that have suggested increases in strength following spinal manipulation were due to descending cortical drive and could not be explained by changes at the level of the spinal cord. Spinal manipulation may therefore be indicated for the patients who have lost tonus of their muscle and/or are

  9. Impact of Spinal Manipulation on Cortical Drive to Upper and Lower Limb Muscles.

    PubMed

    Haavik, Heidi; Niazi, Imran Khan; Jochumsen, Mads; Sherwin, Diane; Flavel, Stanley; Türker, Kemal S

    2016-12-23

    This study investigates whether spinal manipulation leads to changes in motor control by measuring the recruitment pattern of motor units in both an upper and lower limb muscle and to see whether such changes may at least in part occur at the cortical level by recording movement related cortical potential (MRCP) amplitudes. In experiment one, transcranial magnetic stimulation input-output (TMS I/O) curves for an upper limb muscle (abductor pollicus brevis; APB) were recorded, along with F waves before and after either spinal manipulation or a control intervention for the same subjects on two different days. During two separate days, lower limb TMS I/O curves and MRCPs were recorded from tibialis anterior muscle (TA) pre and post spinal manipulation. Dependent measures were compared with repeated measures analysis of variance, with p set at 0.05. Spinal manipulation resulted in a 54.5% ± 93.1% increase in maximum motor evoked potential (MEPmax) for APB and a 44.6% ± 69.6% increase in MEPmax for TA. For the MRCP data following spinal manipulation there were significant difference for amplitude of early bereitschafts-potential (EBP), late bereitschafts potential (LBP) and also for peak negativity (PN). The results of this study show that spinal manipulation leads to changes in cortical excitability, as measured by significantly larger MEPmax for TMS induced input-output curves for both an upper and lower limb muscle, and with larger amplitudes of MRCP component post manipulation. No changes in spinal measures (i.e., F wave amplitudes or persistence) were observed, and no changes were shown following the control condition. These results are consistent with previous findings that have suggested increases in strength following spinal manipulation were due to descending cortical drive and could not be explained by changes at the level of the spinal cord. Spinal manipulation may therefore be indicated for the patients who have lost tonus of their muscle and/or are

  10. MUSCLE INJURIES IN ATHLETES

    PubMed Central

    Barroso, Guilherme Campos; Thiele, Edilson Schwansee

    2015-01-01

    This article had the aim of demonstrating the physiology, diagnosis and treatment of muscle injuries, focusing on athletes and their demands and expectations. Muscle injuries are among the most common complaints in orthopedic practice, occurring both among athletes and among non-athletes. These injuries present a challenge for specialists, due to the slow recovery, during which time athletes are unable to take part in training and competitions, and due to frequent sequelae and recurrences of the injuries. Most muscle injuries (between 10% and 55% of all injuries) occur during sports activities. The muscles most commonly affected are the ischiotibial, quadriceps and gastrocnemius. These muscles go across two joints and are more subject to acceleration and deceleration forces. The treatment for muscle injuries varies from conservative treatment to surgery. New procedures are being used, like the hyperbaric chamber and the use of growth factors. However, there is still a high rate of injury recurrence. Muscle injury continues to be a topic of much controversy. New treatments are being researched and developed, but prevention through muscle strengthening, stretching exercises and muscle balance continues to be the best “treatment”. PMID:27027021

  11. MUSCLE INJURIES IN ATHLETES.

    PubMed

    Barroso, Guilherme Campos; Thiele, Edilson Schwansee

    2011-01-01

    This article had the aim of demonstrating the physiology, diagnosis and treatment of muscle injuries, focusing on athletes and their demands and expectations. Muscle injuries are among the most common complaints in orthopedic practice, occurring both among athletes and among non-athletes. These injuries present a challenge for specialists, due to the slow recovery, during which time athletes are unable to take part in training and competitions, and due to frequent sequelae and recurrences of the injuries. Most muscle injuries (between 10% and 55% of all injuries) occur during sports activities. The muscles most commonly affected are the ischiotibial, quadriceps and gastrocnemius. These muscles go across two joints and are more subject to acceleration and deceleration forces. The treatment for muscle injuries varies from conservative treatment to surgery. New procedures are being used, like the hyperbaric chamber and the use of growth factors. However, there is still a high rate of injury recurrence. Muscle injury continues to be a topic of much controversy. New treatments are being researched and developed, but prevention through muscle strengthening, stretching exercises and muscle balance continues to be the best "treatment".

  12. Weak crystallization theory of metallic alloys

    NASA Astrophysics Data System (ADS)

    Martin, Ivar; Gopalakrishnan, Sarang; Demler, Eugene A.

    2016-06-01

    Crystallization is one of the most familiar, but hardest to analyze, phase transitions. The principal reason is that crystallization typically occurs via a strongly first-order phase transition, and thus rigorous treatment would require comparing energies of an infinite number of possible crystalline states with the energy of liquid. A great simplification occurs when crystallization transition happens to be weakly first order. In this case, weak crystallization theory, based on unbiased Ginzburg-Landau expansion, can be applied. Even beyond its strict range of validity, it has been a useful qualitative tool for understanding crystallization. In its standard form, however, weak crystallization theory cannot explain the existence of a majority of observed crystalline and quasicrystalline states. Here we extend the weak crystallization theory to the case of metallic alloys. We identify a singular effect of itinerant electrons on the form of weak crystallization free energy. It is geometric in nature, generating strong dependence of free energy on the angles between ordering wave vectors of ionic density. That leads to stabilization of fcc, rhombohedral, and icosahedral quasicrystalline (iQC) phases, which are absent in the generic theory with only local interactions. As an application, we find the condition for stability of iQC that is consistent with the Hume-Rothery rules known empirically for the majority of stable iQC; namely, the length of the primary Bragg-peak wave vector is approximately equal to the diameter of the Fermi sphere.

  13. Experimental noiseless linear amplification using weak measurements

    NASA Astrophysics Data System (ADS)

    Ho, Joseph; Boston, Allen; Palsson, Matthew; Pryde, Geoff

    2016-09-01

    The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified. We characterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.

  14. Weak turbulence theory for reactive instability

    SciTech Connect

    Yoon, P. H.

    2010-11-15

    In the present paper, the customary weak turbulence theory is generalized to include reactive instabilities. For the sake of simplicity, the formalism assumes electrostatic perturbation propagating in one-dimensional uniform unmagnetized plasmas. By weak turbulence theory it is meant as the perturbative nonlinear theory based upon Vlasov equation, truncated at the second (or up to third) order nonlinearity and ensemble averaged. By reactive instability it is meant as the plasma instability whose growth rate is not necessarily exceedingly small. The traditional weak turbulence theory found in the literature is applicable only to weakly growing plasma instabilities whose real frequency {omega}{sub k} can be determined from the real part of the dispersion relation, Re {epsilon}(k,{omega}{sub k})=0, while the growth rate may be determined by the Landau formula, {gamma}{sub k}=-Im {epsilon}(k,{omega}{sub k})[{partial_derivative} Re {epsilon}(k,{omega}{sub k})/{partial_derivative}{omega}{sub k}]{sup -1}. This implies the assumption that |{gamma}{sub k}|<<{omega}{sub k}. On the other hand, for reactive instabilities for which {gamma}{sub k}/{omega}{sub k} is not necessarily small, the real frequency and growth/damping rate must be determined from the complex roots of the dispersion relation, {epsilon}(k,{omega}{sub k}+i{gamma}{sub k})=0. The present paper extends the textbook weak turbulence theory to deal with such a situation.

  15. Temporalis muscle hypertrophy and reduced skull eccentricity in Duchenne muscular dystrophy.

    PubMed

    Straathof, C S M; Doorenweerd, N; Wokke, B H A; Dumas, E M; van den Bergen, J C; van Buchem, M A; Hendriksen, J G M; Verschuuren, J J G M; Kan, H E

    2014-10-01

    Muscle hypertrophy and muscle weakness are well known in Duchenne muscular dystrophy. Decreased muscle force can have secondary effects on skeletal growth and development such as facial and dental morphology changes. In this study, we quantified temporal muscle thickness, circumference, and eccentricity of the skull and the head on T1-weighted magnetic resonance imaging (MRI) scans of the head of 15 Duchenne muscular dystrophy patients and 15 controls. Average temporal muscle thickness was significantly increased in patients (12.9 ± 5.2 mm) compared to controls (6.8 ± 1.4 mm) (P < .0001), whereas the shape of the skull was significantly rounder compared to controls. Temporal muscle thickness and skull eccentricity were significantly negatively correlated in patients, and positively in controls. Hypertrophy of the temporal muscles and changes in skull eccentricity appear to occur early in the course of Duchenne muscular dystrophy. Further studies in younger patients are needed to confirm a causal relationship.

  16. Disturbance in weak measurements and the difference between quantum and classical weak values

    NASA Astrophysics Data System (ADS)

    Ipsen, Asger C.

    2015-06-01

    The role of measurement-induced disturbance in weak measurements is of central importance for the interpretation of the weak value. Uncontrolled disturbance can interfere with the postselection process and make the weak value dependent on the details of the measurement process. Here we develop the concept of a generalized weak measurement for classical and quantum mechanics. The two cases appear remarkably similar, but we point out some important differences. A priori it is not clear what the correct notion of disturbance should be in the context of weak measurements. We consider three different notions and get three different results: (1) For a "strong" definition of disturbance, we find that weak measurements are disturbing. (2) For a weaker definition we find that a general class of weak measurements is nondisturbing, but that one gets weak values which depend on the measurement process. (3) Finally, with respect to an operational definition of the "degree of disturbance," we find that the AAV weak measurements are the least disturbing, but that the disturbance is always nonzero.

  17. Continuously Varying Critical Exponents Beyond Weak Universality

    PubMed Central

    Khan, N.; Sarkar, P.; Midya, A.; Mandal, P.; Mohanty, P. K.

    2017-01-01

    Renormalization group theory does not restrict the form of continuous variation of critical exponents which occurs in presence of a marginal operator. However, the continuous variation of critical exponents, observed in different contexts, usually follows a weak universality scenario where some of the exponents (e.g., β, γ, ν) vary keeping others (e.g., δ, η) fixed. Here we report ferromagnetic phase transition in (Sm1−yNdy)0.52Sr0.48MnO3 (0.5 ≤ y ≤ 1) single crystals where all three exponents β, γ, δ vary with Nd concentration y. Such a variation clearly violates both universality and weak universality hypothesis. We propose a new scaling theory that explains the present experimental results, reduces to the weak universality as a special case, and provides a generic route leading to continuous variation of critical exponents and multi-criticality. PMID:28327622

  18. Continuously Varying Critical Exponents Beyond Weak Universality

    NASA Astrophysics Data System (ADS)

    Khan, N.; Sarkar, P.; Midya, A.; Mandal, P.; Mohanty, P. K.

    2017-03-01

    Renormalization group theory does not restrict the form of continuous variation of critical exponents which occurs in presence of a marginal operator. However, the continuous variation of critical exponents, observed in different contexts, usually follows a weak universality scenario where some of the exponents (e.g., β, γ, ν) vary keeping others (e.g., δ, η) fixed. Here we report ferromagnetic phase transition in (Sm1‑yNdy)0.52Sr0.48MnO3 (0.5 ≤ y ≤ 1) single crystals where all three exponents β, γ, δ vary with Nd concentration y. Such a variation clearly violates both universality and weak universality hypothesis. We propose a new scaling theory that explains the present experimental results, reduces to the weak universality as a special case, and provides a generic route leading to continuous variation of critical exponents and multi-criticality.

  19. Phase slips in superconducting weak links

    SciTech Connect

    Kimmel, Gregory; Glatz, Andreas; Aranson, Igor S.

    2017-01-01

    Superconducting vortices and phase slips are primary mechanisms of dissipation in superconducting, superfluid, and cold-atom systems. While the dynamics of vortices is fairly well described, phase slips occurring in quasi-one- dimensional superconducting wires still elude understanding. The main reason is that phase slips are strongly nonlinear time-dependent phenomena that cannot be cast in terms of small perturbations of the superconducting state. Here we study phase slips occurring in superconducting weak links. Thanks to partial suppression of superconductivity in weak links, we employ a weakly nonlinear approximation for dynamic phase slips. This approximation is not valid for homogeneous superconducting wires and slabs. Using the numerical solution of the time-dependent Ginzburg-Landau equation and bifurcation analysis of stationary solutions, we show that the onset of phase slips occurs via an infinite period bifurcation, which is manifested in a specific voltage-current dependence. Our analytical results are in good agreement with simulations.

  20. Sphingomyelinase depresses force and calcium sensitivity of the contractile apparatus in mouse diaphragm muscle fibers

    PubMed Central

    Ferreira, Leonardo F.; Moylan, Jennifer S.; Stasko, Shawn; Smith, Jeffrey D.; Campbell, Kenneth S.

    2012-01-01

    Diseases that result in muscle weakness, e.g., heart failure, are characterized by elevated sphingomyelinase (SMase) activity. In intact muscle, SMase increases oxidants that contribute to diminished muscle force. However, the source of oxidants, specific processes of muscle contraction that are dysfunctional, and biochemical changes underlying the weakness elicited by SMase remain unknown. We tested three hypotheses: 1) SMase-induced depression of muscle force is mediated by mitochondrial reactive oxygen species (ROS), 2) SMase depresses force and calcium sensitivity of the contractile apparatus, and 3) SMase promotes oxidation and phosphorylation of myofibrillar proteins. Our experiments included intact muscle bundles, permeabilized single fibers, and isolated myofibrillar proteins. The mitochondrial-targeted antioxidant d-Arg-2′,6′-dimethyl-Tyr-Lys-Phe-NH2, decreased cytosolic oxidants and protected intact muscle bundles from weakness stimulated by SMase. SMase depressed maximal calcium-activated force by 20% in permeabilized single fibers (in kN/m2: control 117 ± 6; SMase 93 ± 8; P < 0.05). Calcium sensitivity of permeabilized single fibers decreased from 5.98 ± 0.03 (control) to 5.91 ± 0.02 (SMase; P < 0.05). Myofibrillar protein nitrotyrosines, carbonyls, and phosphorylation were unaltered by SMase. Our study shows that the fall in specific force of intact muscle elicited by SMase is mediated by mitochondrial ROS and can be attributed largely to dysfunction of the contractile apparatus. PMID:22362402

  1. Cyclophilin D, a target for counteracting skeletal muscle dysfunction in mitochondrial myopathy

    PubMed Central

    Gineste, Charlotte; Hernandez, Andres; Ivarsson, Niklas; Cheng, Arthur J.; Naess, Karin; Wibom, Rolf; Lesko, Nicole; Bruhn, Helene; Wedell, Anna; Freyer, Christoph; Zhang, Shi-Jin; Carlström, Mattias; Lanner, Johanna T.; Andersson, Daniel C.; Bruton, Joseph D.; Wredenberg, Anna; Westerblad, Håkan

    2015-01-01

    Muscle weakness and exercise intolerance are hallmark symptoms in mitochondrial disorders. Little is known about the mechanisms leading to impaired skeletal muscle function and ultimately muscle weakness in these patients. In a mouse model of lethal mitochondrial myopathy, the muscle-specific Tfam knock-out (KO) mouse, we previously demonstrated an excessive mitochondrial Ca2+ uptake in isolated muscle fibers that could be inhibited by the cyclophilin D (CypD) inhibitor, cyclosporine A (CsA). Here we show that the Tfam KO mice have increased CypD levels, and we demonstrate that this increase is a common feature in patients with mitochondrial myopathy. We tested the effect of CsA treatment on Tfam KO mice during the transition from a mild to terminal myopathy. CsA treatment counteracted the development of muscle weakness and improved muscle fiber Ca2+ handling. Importantly, CsA treatment prolonged the lifespan of these muscle-specific Tfam KO mice. These results demonstrate that CsA treatment is an efficient therapeutic strategy to slow the development of severe mitochondrial myopathy. PMID:26374844

  2. Cyclophilin D, a target for counteracting skeletal muscle dysfunction in mitochondrial myopathy.

    PubMed

    Gineste, Charlotte; Hernandez, Andres; Ivarsson, Niklas; Cheng, Arthur J; Naess, Karin; Wibom, Rolf; Lesko, Nicole; Bruhn, Helene; Wedell, Anna; Freyer, Christoph; Zhang, Shi-Jin; Carlström, Mattias; Lanner, Johanna T; Andersson, Daniel C; Bruton, Joseph D; Wredenberg, Anna; Westerblad, Håkan

    2015-12-01

    Muscle weakness and exercise intolerance are hallmark symptoms in mitochondrial disorders. Little is known about the mechanisms leading to impaired skeletal muscle function and ultimately muscle weakness in these patients. In a mouse model of lethal mitochondrial myopathy, the muscle-specific Tfam knock-out (KO) mouse, we previously demonstrated an excessive mitochondrial Ca(2+) uptake in isolated muscle fibers that could be inhibited by the cyclophilin D (CypD) inhibitor, cyclosporine A (CsA). Here we show that the Tfam KO mice have increased CypD levels, and we demonstrate that this increase is a common feature in patients with mitochondrial myopathy. We tested the effect of CsA treatment on Tfam KO mice during the transition from a mild to terminal myopathy. CsA treatment counteracted the development of muscle weakness and improved muscle fiber Ca(2+) handling. Importantly, CsA treatment prolonged the lifespan of these muscle-specific Tfam KO mice. These results demonstrate that CsA treatment is an efficient therapeutic strategy to slow the development of severe mitochondrial myopathy.

  3. Immunocytochemical localization of myotonin protein kinase on muscle from patients with congenital myotonic dystrophy.

    PubMed

    Tachi, N; Kozuka, N; Ohya, K; Chiba, S; Kikuchi, K

    1996-10-01

    Using a polyclonal anti myotonin-protein kinase (M-PK) antibody against synthetic M-PK peptides corresponding to part of the amino acid sequence, and the immunohistochemical analysis of indirect immunoperoxidase, we have investigated localization of M-PK on muscle from patients with congenital myotonic dystrophy. In congenital myotonic dystrophy (MD) patients, one month and 3 months old, M-PK was weakly expressed at sarcolemma of muscle fibers. In congenital MD patients from 2 to 9 years of age, M-PK was clearly expressed at sarcolemma of muscle fibers. M-PK of immature muscle is weakly expressed at sarcolemma. With aging, M-PK is clearly expressed at sarcolemma of muscle from MD patient and normal control.

  4. Mechanisms of Muscle Denervation in Aging: Insights from a Mouse Model of Amyotrophic Lateral Sclerosis

    PubMed Central

    Park, Kevin H.J

    2015-01-01

    Muscle denervation at the neuromuscular junction (NMJ) is thought to be a contributing factor in age-related muscle weakness. Therefore, understanding the mechanisms that modulate NMJ innervation is a key to developing therapies to combat age-related muscle weakness affecting the elderly. Two mouse models, one lacking the Cu/Zn superoxide dismutase (SOD1) gene and another harboring the transgenic mutant human SOD1 gene, display progressive changes at the NMJ, including muscle endplate fragmentation, nerve terminal sprouting, and denervation. These changes at the NMJ share many of the common features observed in the NMJs of aged mice. In this review, research findings demonstrating the effects of PGC-1α, IGF-1, GDNF, MyoD, myogenin, and miR-206 on NMJ innervation patterns in the G93A SOD1 mice will be highlighted in the context of age-related muscle denervation. PMID:26425392

  5. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  6. Ischemia causes muscle fatigue

    NASA Technical Reports Server (NTRS)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D. M.

    2001-01-01

    The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P < 0.05) than baseline value. Reduced twitch force was correlated in a dose-dependent manner with reduced muscle oxygenation (r = 0.78, P < 0.001). Although the correlation does not prove causation, the results indicate that ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

  7. Precision cosmology with weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Hearin, Andrew P.

    In recent years, cosmological science has developed a highly predictive model for the universe on large scales that is in quantitative agreement with a wide range of astronomical observations. While the number and diversity of successes of this model provide great confidence that our general picture of cosmology is correct, numerous puzzles remain. In this dissertation, I analyze the potential of planned and near future galaxy surveys to provide new understanding of several unanswered questions in cosmology, and address some of the leading challenges to this observational program. In particular, I study an emerging technique called cosmic shear, the weak gravitational lensing produced by large scale structure. I focus on developing strategies to optimally use the cosmic shear signal observed in galaxy imaging surveys to uncover the physics of dark energy and the early universe. In chapter 1 I give an overview of a few unsolved mysteries in cosmology and I motivate weak lensing as a cosmological probe. I discuss the use of weak lensing as a test of general relativity in chapter 2 and assess the threat to such tests presented by our uncertainty in the physics of galaxy formation. Interpreting the cosmic shear signal requires knowledge of the redshift distribution of the lensed galaxies. This redshift distribution will be significantly uncertain since it must be determined photometrically. In chapter 3 I investigate the influence of photometric redshift errors on our ability to constrain dark energy models with weak lensing. The ability to study dark energy with cosmic shear is also limited by the imprecision in our understanding of the physics of gravitational collapse. In chapter 4 I present the stringent calibration requirements on this source of uncertainty. I study the potential of weak lensing to resolve a debate over a long-standing anomaly in CMB measurements in chapter 5. Finally, in chapter 6 I summarize my findings and conclude with a brief discussion of my

  8. Extrapolating Weak Selection in Evolutionary Games

    PubMed Central

    Wu, Bin; García, Julián; Hauert, Christoph; Traulsen, Arne

    2013-01-01

    In evolutionary games, reproductive success is determined by payoffs. Weak selection means that even large differences in game outcomes translate into small fitness differences. Many results have been derived using weak selection approximations, in which perturbation analysis facilitates the derivation of analytical results. Here, we ask whether results derived under weak selection are also qualitatively valid for intermediate and strong selection. By “qualitatively valid” we mean that the ranking of strategies induced by an evolutionary process does not change when the intensity of selection increases. For two-strategy games, we show that the ranking obtained under weak selection cannot be carried over to higher selection intensity if the number of players exceeds two. For games with three (or more) strategies, previous examples for multiplayer games have shown that the ranking of strategies can change with the intensity of selection. In particular, rank changes imply that the most abundant strategy at one intensity of selection can become the least abundant for another. We show that this applies already to pairwise interactions for a broad class of evolutionary processes. Even when both weak and strong selection limits lead to consistent predictions, rank changes can occur for intermediate intensities of selection. To analyze how common such games are, we show numerically that for randomly drawn two-player games with three or more strategies, rank changes frequently occur and their likelihood increases rapidly with the number of strategies . In particular, rank changes are almost certain for , which jeopardizes the predictive power of results derived for weak selection. PMID:24339769

  9. OGT and OGA expression in postmenopausal skeletal muscle associates with hormone replacement therapy and muscle cross-sectional area.

    PubMed

    Toivonen, Minna H M; Pöllänen, Eija; Ahtiainen, Maarit; Suominen, Harri; Taaffe, Dennis R; Cheng, Sulin; Takala, Timo; Kujala, Urho M; Tammi, Markku I; Sipilä, Sarianna; Kovanen, Vuokko

    2013-12-01

    Protein glycosylation via O-linked N-acetylglucosaminylation (O-GlcNAcylation) is an important post-translational regulatory mechanism mediated by O-GlcNAc transferase (OGT) and responsive to nutrients and stress. OGT attaches an O-GlcNAc moiety to proteins, while O-GlcNAcase (OGA) catalyzes O-GlcNAc removal. In skeletal muscle of experimental animals, prolonged increase in O-GlcNAcylation associates with age and muscle atrophy. Here we examined the effects of hormone replacement therapy (HRT) and power training (PT) on muscle OGT and OGA gene expression in postmenopausal women generally prone to age-related muscle weakness. In addition, the associations of OGT and OGA gene expressions with muscle phenotype were analyzed. Twenty-seven 50-57-year-old women participated in a yearlong randomized placebo-controlled trial: HRT (n=10), PT (n=8) and control (n=9). OGT and OGA mRNA levels were measured from muscle samples obtained at baseline and after one year. Knee extensor muscle cross-sectional area (CSA), knee extension force, running speed and vertical jumping height were measured. During the yearlong intervention, HRT suppressed the aging-associated upregulation of OGT mRNA that occurred in the controls. The effects of PT were similar but weaker. HRT also tended to increase the OGA mRNA level compared to the controls. The change in the ratio of OGT to OGA gene expressions correlated negatively with the change in muscle CSA. Our results suggest that OGT and OGA gene expressions are associated with muscle size during the critical postmenopausal period. HRT and PT influence muscle OGT and OGA gene expression, which may be one of the mechanisms by which HRT and PT prevent aging-related loss of muscle mass.

  10. Weak Lie symmetry and extended Lie algebra

    SciTech Connect

    Goenner, Hubert

    2013-04-15

    The concept of weak Lie motion (weak Lie symmetry) is introduced. Applications given exhibit a reduction of the usual symmetry, e.g., in the case of the rotation group. In this context, a particular generalization of Lie algebras is found ('extended Lie algebras') which turns out to be an involutive distribution or a simple example for a tangent Lie algebroid. Riemannian and Lorentz metrics can be introduced on such an algebroid through an extended Cartan-Killing form. Transformation groups from non-relativistic mechanics and quantum mechanics lead to such tangent Lie algebroids and to Lorentz geometries constructed on them (1-dimensional gravitational fields).

  11. Critical level statistics for weakly disordered graphene.

    PubMed

    Amanatidis, E; Kleftogiannis, I; Katsanos, D E; Evangelou, S N

    2014-04-16

    In two dimensions chaotic level statistics with the Wigner spacing distribution P(S) is expected for massless fermions in the Dirac region. The obtained P(S) for weakly disordered finite graphene samples with zigzag edges turns out, however, to be neither chaotic (Wigner) nor localized (Poisson). It is similar to the intermediate statistics at the critical point of the Anderson metal-insulator transition. The quantum transport of finite graphene for weak disorder, with critical level statistics can occur via edge states as in topological insulators, and for strong disorder, graphene behaves as an ordinary Anderson insulator with Poisson statistics.

  12. Landau Weak Crystallization Theory and its Applications

    NASA Astrophysics Data System (ADS)

    Kats, E. I.

    Aim of this lecture is to explain main features and ingredients of weak first order phase transitions between liquid-like (uniform in space) and solid-like (non-uniform with characteristic wave vector q0) states. We illustrate how this theory (traditionally termed as Landau weak crystallization theory) works. We consider two examples describing universal temperature dependence of shear viscosity in liquids, and so-called main phase transition in membranes. Our results are in a good qualitative agreement with experimental data, offering a deeper understanding of this kind of phase transitions. We discuss also why and where predicted universal effects can be masked.

  13. Simple understanding of quantum weak values

    PubMed Central

    Qin, Lupei; Feng, Wei; Li, Xin-Qi

    2016-01-01

    In this work we revisit the important and controversial concept of quantum weak values, aiming to provide a simplified understanding to its associated physics and the origin of anomaly. Taking the Stern-Gerlach setup as a working system, we base our analysis on an exact treatment in terms of quantum Bayesian approach. We also make particular connection with a very recent work, where the anomaly of the weak values was claimed from the pure statistics in association with “disturbance” and “post-selection”, rather than the unique quantum nature. Our analysis resolves the related controversies through a clear and quantitative way. PMID:26838670

  14. Measuring the dark side (with weak lensing)

    SciTech Connect

    Amendola, Luca

    2008-04-15

    We introduce a convenient parameterization of dark energy models that is general enough to include several modified gravity models and generalized forms of dark energy. In particular we take into account the linear perturbation growth factor, the anisotropic stress and the modified Poisson equation. We discuss the sensitivity of large-scale weak lensing surveys like the proposed DUNE satellite to these parameters (assuming systematic errors can be controlled). We find that a large-scale weak lensing tomographic survey is able to easily distinguish the Dvali-Gabadadze-Porrati model from {Lambda}CDM and to determine the perturbation growth index to an absolute error of 0.02-0.04.

  15. Geometric Integration of Weakly Dissipative Systems

    NASA Astrophysics Data System (ADS)

    Modin, K.; Führer, C.; Soöderlind, G.

    2009-09-01

    Some problems in mechanics, e.g. in bearing simulation, contain subsystems that are conservative as well as weakly dissipative subsystems. Our experience is that geometric integration methods are often superior for such systems, as long as the dissipation is weak. Here we develop adaptive methods for dissipative perturbations of Hamiltonian systems. The methods are "geometric" in the sense that the form of the dissipative perturbation is preserved. The methods are linearly explicit, i.e., they require the solution of a linear subsystem. We sketch an analysis in terms of backward error analysis and numerical comparisons with a conventional RK method of the same order is given.

  16. Evaluation of Respiratory Muscle Strength in Mouth Breathers: Clinical Evidences

    PubMed Central

    Andrade da Cunha, Renata; Andrade da Cunha, Daniele; Assis, Roberta Borba; Bezerra, Luciana Ângelo; Justino da Silva, Hilton

    2013-01-01

    Introduction The child who chronically breathes through the mouth may develop a weakness of the respiratory muscles. Researchers and clinical are seeking for methods of instrumental evaluation to gather complementary data to clinical evaluations. With this in mind, it is important to evaluate breathing muscles in the child with Mouth Breathing. Objective To develop a review to investigate studies that used evaluation methods of respiratory muscle strength in mouth breathers. Data Synthesis  The authors were unanimous in relation to manovacuometry method as a way to evaluate respiratory pressures in Mouth Breathing children. Two of them performed with an analog manovacuometer and the other one, digital. The studies were not evaluated with regard to the method efficacy neither the used instruments. Conclusion There are few studies evaluating respiratory muscle strength in Mouth Breathing people through manovacuometry and the low methodological rigor of the analyzed studies hindered a reliable result to support or refuse the use of this technique. PMID:25992108

  17. Research opportunities in muscle atrophy

    NASA Technical Reports Server (NTRS)

    Herbison, G. J.; Talbot, J. M.

    1984-01-01

    A trophy of skeletal muscle; muscle a trophy associated with manned space flight; the nature, causes, and mechanisms of muscle atrophy associated with space flight, selected physiological factors, biochemical aspects, and countermeasures are addressed.

  18. Respiratory muscle plasticity.

    PubMed

    Gransee, Heather M; Mantilla, Carlos B; Sieck, Gary C

    2012-04-01

    Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. As such, respiratory muscle is in a constant state of remodeling, and the basis of muscle's plasticity is its ability to change protein expression and resultant protein balance in response to varying environmental conditions. Here, we will describe the changes of respiratory muscle imposed by extrinsic changes in mechanical load, activity, and innervation. Although there is a large body of literature on the structural and functional plasticity of respiratory muscles, we are only beginning to understand the molecular-scale protein changes that contribute to protein balance. We will give an overview of key mechanisms regulating protein synthesis and protein degradation, as well as the complex interactions between them. We suggest future application of a systems biology approach that would develop a mathematical model of protein balance and greatly improve treatments in a variety of clinical settings related to maintaining both muscle mass and optimal contractile function of respiratory muscles.

  19. Stressed out: the skeletal muscle ryanodine receptor as a target of stress

    PubMed Central

    Bellinger, Andrew M.; Mongillo, Marco; Marks, Andrew R.

    2008-01-01

    Over the past century, understanding the mechanisms underlying muscle fatigue and weakness has been the focus of much investigation. However, the dominant theory in the field, that lactic acidosis causes muscle fatigue, is unlikely to tell the whole story. Recently, dysregulation of sarcoplasmic reticulum (SR) Ca2+ release has been associated with impaired muscle function induced by a wide range of stressors, from dystrophy to heart failure to muscle fatigue. Here, we address current understandings of the altered regulation of SR Ca2+ release during chronic stress, focusing on the role of the SR Ca2+ release channel known as the type 1 ryanodine receptor. PMID:18246195

  20. Becker muscular dystrophy with widespread muscle hypertrophy and a non-sense mutation of exon 2.

    PubMed

    Witting, N; Duno, M; Vissing, J

    2013-01-01

    Becker muscular dystrophy features progressive proximal weakness, wasting and often focal hypertrophy. We present a patient with pain and cramps from adolescence. Widespread muscle hypertrophy, preserved muscle strength and a 10-20-fold raised CPK were noted. Muscle biopsy was dystrophic, and Western blot showed a 95% reduction of dystrophin levels. Genetic analyses revealed a non-sense mutation in exon 2 of the dystrophin gene. This mutation is predicted to result in a Duchenne phenotype, but resulted in a mild Becker muscular dystrophy with widespread muscle hypertrophy. We suggest that this unusual phenotype is caused by translation re-initiation downstream from the mutation site.

  1. Cellular mechanism of eccentric-induced muscle injury and its relationship with sarcomere heterogeneity

    PubMed Central

    Choi, Seung Jun

    2014-01-01

    Activity-induced muscle injury and dysfunction have been identified as key components of musculoskeletal injuries. These injuries often occur following eccentric contractions, when the muscle is under tension and stretched by a force that is greater than the force generated by the muscle. Many daily activities require muscles to perform eccentric contractions, including walking (or running) downhill or down stairs, lowering heavy objects, and landing from a jump. Injuries often occur when these activities are performed at high intensity or for prolonged periods of time. General features of eccentric-induced muscle injury are well documented and include disruption of intracellular muscle structure, prolonged muscle weakness and dysfunction, a delayed-onset muscle soreness, and inflammation. Several weeks are required for the affected tissue to fully regenerate and recover from eccentric-induced muscle injury. Possible mechanisms responsible for eccentric-induced muscle injury are activation impairment and structural disruption of the sarcomere. These two factors seem to be the main sources of eccentric-induced muscle injury. Rather than being separate mechanisms they may be complimentary and interact with each other. Therefore, in this review we will focus on the two main cellular mechanism of muscle cell injury following accustomed eccentric contraction. PMID:25210693

  2. Cellular mechanism of eccentric-induced muscle injury and its relationship with sarcomere heterogeneity.

    PubMed

    Choi, Seung Jun

    2014-08-01

    Activity-induced muscle injury and dysfunction have been identified as key components of musculoskeletal injuries. These injuries often occur following eccentric contractions, when the muscle is under tension and stretched by a force that is greater than the force generated by the muscle. Many daily activities require muscles to perform eccentric contractions, including walking (or running) downhill or down stairs, lowering heavy objects, and landing from a jump. Injuries often occur when these activities are performed at high intensity or for prolonged periods of time. General features of eccentric-induced muscle injury are well documented and include disruption of intracellular muscle structure, prolonged muscle weakness and dysfunction, a delayed-onset muscle soreness, and inflammation. Several weeks are required for the affected tissue to fully regenerate and recover from eccentric-induced muscle injury. Possible mechanisms responsible for eccentric-induced muscle injury are activation impairment and structural disruption of the sarcomere. These two factors seem to be the main sources of eccentric-induced muscle injury. Rather than being separate mechanisms they may be complimentary and interact with each other. Therefore, in this review we will focus on the two main cellular mechanism of muscle cell injury following accustomed eccentric contraction.

  3. The evaluation of relationship between vitamin D and muscle power by micro manual muscle tester in end-stage renal disease patients.

    PubMed

    Zahed, Nargesosadat; Chehrazi, Saghar; Falaknasi, Kianosh

    2014-09-01

    Muscle force of lower limb is a major factor for sustaining physical activity. Decreased muscle force can limit physical activity, which can increase mortality and morbidity in end-stage renal disease (ESRD) patients. Muscle force depends on several factors. One of the most important factors is 25-hydroxy vitamin D (25-OHD) that affects muscle function in both uremic and non-uremic patients. The aim of this study was to investigate the association between serum level of 25-OHD and muscle force of lower extremities in hemodialysis patients estimated by a Micro Manual Muscle Tester, a digital instrument that measures muscle force in kilograms This cross-sectional study was performed on 135 adult patients, 69 male (51%) and 66 female (69%) (mean: 1.4, standard deviation: 0.5), undergoing hemodialysis. Standard biochemistry parameters were measured before hemodialysis, including 25-OHD, calcium, albumin, para-hyroid hormone and C-reactive protein (CRP). Based on the result of serum level of 25-OHD, patients were classified into the following three groups: 85 patients (63%) were 25-OHD deficient (25-OHD <30), 43 patients (32%) had a normal level of 25-OHD (30-70) and seven patients (5%) had a toxic level of 25-OHD (>70) (mean: 1.42, standard deviation: 0.59). Also, based on the result of muscle force, patients were classified into the following three groups: 84/133 patients (62%) had weak muscle force (<5 kg), 46/133 patients (34%) had normal muscle force (5-10 kg) and three patients (21%) had strong muscle force (>10 kg) (mean: 1.39, standard deviation: 0.53). There was a significant relation between 25-OHD level and muscle force (P = 0.02), between age and muscle force (P = 0.002) and between gender and muscle force (P <0.001). In our opinion, 25-OHD can be a useful drug in ESRD patients to improve muscle force and physical activity.

  4. Onion artificial muscles

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Chun; Shih, Wen-Pin; Chang, Pei-Zen; Lai, Hsi-Mei; Chang, Shing-Yun; Huang, Pin-Chun; Jeng, Huai-An

    2015-05-01

    Artificial muscles are soft actuators with the capability of either bending or contraction/elongation subjected to external stimulation. However, there are currently no artificial muscles that can accomplish these actions simultaneously. We found that the single layered, latticed microstructure of onion epidermal cells after acid treatment became elastic and could simultaneously stretch and bend when an electric field was applied. By modulating the magnitude of the voltage, the artificial muscle made of onion epidermal cells would deflect in opposing directions while either contracting or elongating. At voltages of 0-50 V, the artificial muscle elongated and had a maximum deflection of -30 μm; at voltages of 50-1000 V, the artificial muscle contracted and deflected 1.0 mm. The maximum force response is 20 μN at 1000 V.

  5. Molecular Handshake: Recognition through Weak Noncovalent Interactions

    ERIC Educational Resources Information Center

    Murthy, Parvathi S.

    2006-01-01

    The weak noncovalent interactions between substances, the handshake in the form of electrostatic interactions, van der Waals' interactions or hydrogen bonding is universal to all living and nonliving matter. They significantly influence the molecular and bulk properties and behavior of matter. Their transient nature affects chemical reactions and…

  6. Weak radiative baryonic decays of B mesons

    SciTech Connect

    Kohara, Yoji

    2004-11-01

    Weak radiative baryonic B decays B{yields}B{sub 1}B{sub 2}-bar{gamma} are studied under the assumption of the short-distance b{yields}s{gamma} electromagnetic penguin transition dominance. The relations among the decay rates of various decay modes are derived.

  7. Engineering molecular crystals with abnormally weak cohesion.

    PubMed

    Maly, Kenneth E; Gagnon, Eric; Wuest, James D

    2011-05-14

    Adding astutely placed methyl groups to hexaphenylbenzene increases molecular weight but simultaneously weakens key C-H···π interactions, thereby leading to decreased enthalpies of sublimation and showing that materials with abnormally weak cohesion can be made by identifying and then obstructing interactions that help control association.

  8. Resource Letter WI-1: Weak Interactions

    ERIC Educational Resources Information Center

    Holstein, Barry R.

    1977-01-01

    Provides a listing of sources of literature and teaching aids to improve course content in the fields of: weak interactions, beta decay, orbital electron capture, muon capture, semileptonic decay, nonleptonic processes, parity violation in nuclei, neutrino physics, and parity violation in atomic physics. (SL)

  9. Musculotendinous infraspinatus rupture and shoulder weakness.

    PubMed

    Lipford, Melissa C; Bond, Jeffrey R; Steinmann, Scott P; Kumar, Neeraj

    2011-12-01

    We report a patient with bilateral simultaneous onset of weakness of shoulder lateral rotation due to musculotendinous infraspinatus rupture that occurred after shoulder steroid injections. Disruption of the musculotendinous junction of the infraspinatus is a rare recently described entity. Electromyography is normal, and magnetic resonance image findings are characteristic.

  10. Modeling, Measuring, and Compensating Color Weak Vision.

    PubMed

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-06-01

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color-weak observers. The two main applications are the simulation of the perception of a color weak observer for a color-normal observer, and the compensation of color images in a way that a color-weak observer has approximately the same perception as a color-normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticeable-differences between the colors which are measured with the help of color-matching experiments. The constructed mappings are the isometries of Riemann spaces that preserve the perceived color differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared with the previously used methods, this method is free from approximation errors due to local linearizations, and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyze the variations of the Riemann metrics for different observers obtained from new color-matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential tests.

  11. Modelling, Measuring and Compensating Color Weak Vision.

    PubMed

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-03-08

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color weak observers. The two main applications are the simulation of the perception of a color weak observer for a color normal observer and the compensation of color images in a way that a color weak observer has approximately the same perception as a color normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticable-differences between color which are measured with the help of color-matching experiments. The constructed mappings are isometries of Riemann spaces that preserve the perceived color-differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared to previously used methods this method is free from approximation errors due to local linearizations and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyse the variations of the Riemann metrics for different observers obtained from new color matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential (SD) tests.

  12. Chronic exercise preserves lean muscle mass in masters athletes.

    PubMed

    Wroblewski, Andrew P; Amati, Francesca; Smiley, Mark A; Goodpaster, Bret; Wright, Vonda

    2011-09-01

    Aging is commonly associated with a loss of muscle mass and strength, resulting in falls, functional decline, and the subjective feeling of weakness. Exercise modulates the morbidities of muscle aging. Most studies, however, have examined muscle-loss changes in sedentary aging adults. This leaves the question of whether the changes that are commonly associated with muscle aging reflect the true physiology of muscle aging or whether they reflect disuse atrophy. This study evaluated whether high levels of chronic exercise prevents the loss of lean muscle mass and strength experienced in sedentary aging adults. A cross-section of 40 high-level recreational athletes ("masters athletes") who were aged 40 to 81 years and trained 4 to 5 times per week underwent tests of health/activity, body composition, quadriceps peak torque (PT), and magnetic resonance imaging of bilateral quadriceps. Mid-thigh muscle area, quadriceps area (QA), subcutaneous adipose tissue, and intramuscular adipose tissue were quantified in magnetic resonance imaging using medical image processing, analysis, and visualization software. One-way analysis of variance was used to examine age group differences. Relationships were evaluated using Spearman correlations. Mid-thigh muscle area (P = 0.31) and lean mass (P = 0.15) did not increase with age and were significantly related to retention of mid-thigh muscle area (P < 0.0001). This occurred despite an increase in total body fat percentage (P = 0.003) with age. Mid-thigh muscle area (P = 0.12), QA (P = 0.17), and quadriceps PT did not decline with age. Specific strength (strength per QA) did not decline significantly with age (P = 0.06). As muscle area increased, PT increased significantly (P = 0.008). There was not a significant relationship between intramuscular adipose tissue (P = 0.71) or lean mass (P = 0.4) and PT. This study contradicts the common observation that muscle mass and strength decline as a function of aging alone. Instead, these

  13. Anatomy of the pectoral and forelimb muscles of wildtype and green fluorescent protein-transgenic axolotls and comparison with other tetrapods including humans: a basis for regenerative, evolutionary and developmental studies

    PubMed Central

    Diogo, R; Tanaka, E M

    2012-01-01

    stated in the literature, A. mexicanum has a muscle coracoradialis that has both a well developed proximal fleshy belly and a distal long and thin tendon, supporting the idea that this muscle very likely corresponds to at least part of the amniote biceps brachii. Our observations also: (i) confirmed that the flexores digitorum minimi, interphalangeus digiti 3, pronator quadratus and palmaris profundus 1 are present as distinct muscles in A. mexicanum, supporting the idea that the latter muscle does not correspond to the pronator accessorius of reptiles; (ii) confirmed that the so-called extensor antebrachii radialis is present as a distinct muscle in this species and, importantly, indicated that this muscle corresponds to the supinator of other tetrapods; (iii) showed that, contrary to some other urodeles, including some other Ambystoma species, there is no distinct muscle epitrochleoanconeus in A. mexicanum and; (iv) showed that the ulnar and radial bundles of the abductor et extensor digiti 1 correspond to the abductor pollicis longus and extensor pollicis longus of other tetrapods, respectively. PMID:22957800

  14. Cosmological model discrimination with weak lensing

    NASA Astrophysics Data System (ADS)

    Pires, S.; Starck, J.-L.; Amara, A.; Réfrégier, A.; Teyssier, R.

    2009-10-01

    Weak gravitational lensing provides a unique way of mapping directly the dark matter in the Universe. The majority of lensing analyses use the two-point statistics of the cosmic shear field to constrain the cosmological model, a method that is affected by degeneracies, such as that between σ8 and Ωm which are respectively the rms of the mass fluctuations on a scale of 8 Mpc/h and the matter density parameter, both at z = 0. However, the two-point statistics only measure the Gaussian properties of the field, and the weak lensing field is non-Gaussian. It has been shown that the estimation of non-Gaussian statistics for weak lensing data can improve the constraints on cosmological parameters. In this paper, we systematically compare a wide range of non-Gaussian estimators to determine which one provides tighter constraints on the cosmological parameters. These statistical methods include skewness, kurtosis, and the higher criticism test, in several sparse representations such as wavelet and curvelet; as well as the bispectrum, peak counting, and a newly introduced statistic called wavelet peak counting (WPC). Comparisons based on sparse representations indicate that the wavelet transform is the most sensitive to non-Gaussian cosmological structures. It also appears that the most helpful statistic for non-Gaussian characterization in weak lensing mass maps is the WPC. Finally, we show that the σ8 - Ωm degeneracy could be even better broken if the WPC estimation is performed on weak lensing mass maps filtered by the wavelet method, MRLens.

  15. Cosmological model discrimination from weak lensing data

    NASA Astrophysics Data System (ADS)

    Pires, S.; Starck, J.-L.; Amara, A.; Réfrégier, A.; Teyssier, R.

    2010-06-01

    Weak gravitational lensing provides a unique way of mapping directly the dark matter in the Universe. The majority of lensing analyses use the two-point statistics of the cosmic shear field to constrain the cosmological model, a method that is affected by degeneracies, such as that between σ8 and Ωm which are respectively the rms of the mass fluctuations on a scale of 8 Mpc/h and the matter density parameter, both at z = 0. However, the two-point statistics only measure the Gaussian properties of the field, and the weak lensing field is non-Gaussian. It has been shown that the estimation of non-Gaussian statistics for weak lensing data can improve the constraints on cosmological parameters. In this paper, we systematically compare a wide range of non-Gaussian estimators to determine which one provides tighter constraints on the cosmological parameters. These statistical methods include skewness, kurtosis, and the higher criticism test, in several sparse representations such as wavelet and curvelet; as well as the bispectrum, peak counting, and a newly introduced statistic called wavelet peak counting (WPC). Comparisons based on sparse representations indicate that the wavelet transform is the most sensitive to non-Gaussian cosmological structures. It also appears that the most helpful statistic for non-Gaussian characterization in weak lensing mass maps is the WPC. Finally, we show that the σ8-Ωm degeneracy could be even better broken if the WPC estimation is performed on weak lensing mass maps filtered by the wavelet method, MRLens.

  16. Experiment K-6-09. Morphological and biochemical investigation of microgravity-induced nerve and muscle breakdown. Part 1: Investigation of nerve and muscle breakdown during spaceflight; Part 2: Biochemical analysis of EDL and PLT muscles

    NASA Technical Reports Server (NTRS)

    Riley, D. A.; Ellis, S.; Bain, J.; Sedlak, F.; Slocum, G.; Oganov, V.

    1990-01-01

    The present findings on rat hindlimb muscles suggest that skeletal muscle weakness induced by prolonged spaceflight can result from a combination of muscle fiber atrophy, muscle fiber segmental necrosis, degeneration of motor nerve terminals and destruction of microcirculatory vessels. Damage was confined to the red adductor longus (AL) and soleus muscles. The midbelly region of the AL muscle had more segmental necrosis and edema than the ends. Macrophages and neutrophils were the major mononucleated cells infiltrating and phagocytosing the cellular debris. Toluidine blue-positive mast cells were significantly decreased in Flight AL muscles compared to controls; this indicated that degranulation of mast cells contributed to tissue edema. Increased ubiquitination of disrupted myofibrils may have promoted myofilament degradation. Overall, mitochondria content and SDH activity were normal, except for a decrease in the subsarcolemmal region. The myofibrillar ATPase activity shifted toward the fast type in the Flight AL muscles. Some of the pathological changes may have occurred or been exacerbated during the 2 day postflight period of readaptation to terrestrial gravity. While simple atrophy should be reversible by exercise, restoration of pathological changes depends upon complex processes of regeneration by stem cells. Initial signs of muscle and nerve fiber regeneration were detected. Even though regeneration proceeds on Earth, the space environment may inhibit repair and cause progressive irreversible deterioration during long term missions. Muscles obtained from Flight rats sacrificed immediately (within a few hours) after landing are needed to distinguish inflight changes from postflight readaptation.

  17. Ultrasound evaluation of intrinsic plantar muscles and fascia in hallux valgus: A case-control study.

    PubMed

    Lobo, César Calvo; Marín, Alejandro Garrido; Sanz, David Rodríguez; López, Daniel López; López, Patricia Palomo; Morales, Carlos Romero; Corbalán, Irene Sanz

    2016-11-01

    A cross-sectional area (CSA) and thickness reduction of the abductor hallucis (AbH) is shown in subjects with hallux valgus (HV). To date, other soft-tissue structures have not been researched in relation with HV. The aim of this study was to compare the CSA and thickness of the intrinsic plantar muscles and fascia (PF) between feet with and without HV. Therefore, a cross-sectional and case-control study was performed using B-mode with an iU22 Philips ultrasound system and a 5 to 17-MHz transducer. The CSA and thickness were measured for the AbH, flexor digitorum brevis (FDB) and flexor hallucis brevis (FHB), and also the thickness for the anterior, middle, and posterior PF portions. A convenience sample of 40 feet, 20 with HV and 20 without HV, was recruited from a clinical and research center. A multivariate regression analysis using linear regression was performed to evaluate the ultrasound imaging measurements (α = 0.05). Consequently, statistically significant differences were observed between the groups (P < 0.05) for the AbH and FHB thickness, and CSA reduction, and also the plantar fascia thickness increase in favor of the HV group. On the contrary, the FDB thickness and CSA did not show statistically significant differences (P ≥ 0.05). In conclusion, the CSA and thickness of the AbH and FHB intrinsic plantar muscles are reduced, whereas the thickness of the anterior, middle, and posterior PF portions are increased, in subjects with HV compared with those without HV.

  18. Ultrasound evaluation of intrinsic plantar muscles and fascia in hallux valgus

    PubMed Central

    Lobo, César Calvo; Marín, Alejandro Garrido; Sanz, David Rodríguez; López, Daniel López; López, Patricia Palomo; Morales, Carlos Romero; Corbalán, Irene Sanz

    2016-01-01

    Abstract A cross-sectional area (CSA) and thickness reduction of the abductor hallucis (AbH) is shown in subjects with hallux valgus (HV). To date, other soft-tissue structures have not been researched in relation with HV. The aim of this study was to compare the CSA and thickness of the intrinsic plantar muscles and fascia (PF) between feet with and without HV. Therefore, a cross-sectional and case-control study was performed using B-mode with an iU22 Philips ultrasound system and a 5 to 17-MHz transducer. The CSA and thickness were measured for the AbH, flexor digitorum brevis (FDB) and flexor hallucis brevis (FHB), and also the thickness for the anterior, middle, and posterior PF portions. A convenience sample of 40 feet, 20 with HV and 20 without HV, was recruited from a clinical and research center. A multivariate regression analysis using linear regression was performed to evaluate the ultrasound imaging measurements (α = 0.05). Consequently, statistically significant differences were observed between the groups (P < 0.05) for the AbH and FHB thickness, and CSA reduction, and also the plantar fascia thickness increase in favor of the HV group. On the contrary, the FDB thickness and CSA did not show statistically significant differences (P ≥ 0.05). In conclusion, the CSA and thickness of the AbH and FHB intrinsic plantar muscles are reduced, whereas the thickness of the anterior, middle, and posterior PF portions are increased, in subjects with HV compared with those without HV. PMID:27828846

  19. Age at spinal cord injury determines muscle strength

    PubMed Central

    Thomas, Christine K.; Grumbles, Robert M.

    2014-01-01

    As individuals with spinal cord injury (SCI) age they report noticeable deficits in muscle strength, endurance and functional capacity when performing everyday tasks. These changes begin at ~45 years. Here we present a cross-sectional analysis of paralyzed thenar muscle and motor unit contractile properties in two datasets obtained from different subjects who sustained a cervical SCI at different ages (≤46 years) in relation to data from uninjured age-matched individuals. First, completely paralyzed thenar muscles were weaker when C6 SCI occurred at an older age. Muscles were also significantly weaker if the injury was closer to the thenar motor pools (C6 vs. C4). More muscles were strong (>50% uninjured) in those injured at a younger (≤25 years) vs. young age (>25 years), irrespective of SCI level. There was a reduction in motor unit numbers in all muscles tested. In each C6 SCI, only ~30 units survived vs. 144 units in uninjured subjects. Since intact axons only sprout 4–6 fold, the limits for muscle reinnervation have largely been met in these young individuals. Thus, any further reduction in motor unit numbers with time after these injuries will likely result in chronic denervation, and may explain the late-onset muscle weakness routinely described by people with SCI. In a second dataset, paralyzed thenar motor units were more fatigable than uninjured units. This gap widened with age and will reduce functional reserve. Force declines were not due to electromyographic decrements in either group so the site of failure was beyond excitation of the muscle membrane. Together, these results suggest that age at SCI is an important determinant of long-term muscle strength, and fatigability, both of which influence functional capacity. PMID:24478643

  20. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy

    PubMed Central

    Vuillerot, Carole; Tiffreau, Vincent; Peudenier, Sylviane; Cuisset, Jean-Marie; Pereon, Yann; Leboeuf, Fabien; Delporte, Ludovic; Delpierre, Yannick; Gross, Raphaël

    2016-01-01

    The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity. PMID:27622734

  1. Saturated muscle activation contributes to compensatory reaching strategies following stroke

    PubMed Central

    McCrea, Patrick H; Eng, Janice J; Hodgson, Antony J

    2012-01-01

    The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for twenty persons with chronic stroke and ten healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the non-paretic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task. PMID:16014786

  2. Saturated muscle activation contributes to compensatory reaching strategies after stroke.

    PubMed

    McCrea, Patrick H; Eng, Janice J; Hodgson, Antony J

    2005-11-01

    The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for 20 persons with chronic stroke and 10 healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the nonparetic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task.

  3. Skeletal Muscle Function Deficits in the Elderly: Current Perspectives on Resistance Training

    PubMed Central

    Papa, Evan V.; Dong, Xiaoyang; Hassan, Mahdi

    2017-01-01

    A variety of changes in skeletal muscle occur with aging. Sarcopenia is the age-associated loss of muscle mass and is one of the main contributors to musculoskeletal impairments in the elderly. Traditional definitions of sarcopenia focused on the size of human skeletal muscle. However, increasing evidence in older adults suggests that low muscle mass is associated with weakness, and weakness is strongly associated with function and disability. In recent years a global trend has shifted toward more encompassing definitions for the loss of muscle mass which include decreases in physical function. This review focuses on skeletal muscle function deficits in the elderly and how these age-associated deficits can be ameliorated by resistance training. We set forth evidence that skeletal muscle deficits arise from changes within the muscle, including reduced fiber size, decreased satellite cell and fiber numbers, and decreased expression of myosin heavy chain (MHC) isoform IIa. Finally, we provide recommendations for clinical geriatric practice regarding how resistance training can attenuate the increase in age-associated skeletal muscle function deficits. Practitioners should consider encouraging patients who are reluctant to exercise to move along a continuum of activity between “no acticity” on one end and “recommended daily amounts” on the other. PMID:28191501

  4. Skeletal muscle response to inflammation--lessons for chronic obstructive pulmonary disease.

    PubMed

    Reid, W Darlene; Rurak, Jennifer; Harris, R Luke

    2009-10-01

    To describe how inflammation affects muscle adaptation and performance in people with chronic obstructive pulmonary disease. In chronic obstructive pulmonary disease, an increasingly sedentary lifestyle is a primary contributor to muscle dysfunction that results in a loss of mobility and independence and, ultimately, mortality. Given the systemic chronic inflammation and profound limb muscle atrophy in chronic obstructive pulmonary disease, it is tempting to speculate that the inflammatory process is deleterious to skeletal muscle. In healthy people, however, the inflammatory process initially is dominated by a destructive phase that is tightly regulated and modulates a reparative, regenerative phase. Although the inflammatory process and associated oxidative stress is more closely connected to muscle wasting in animal models of chronic obstructive pulmonary disease, the causative role of inflammation toward muscle atrophy and weakness in people with chronic obstructive pulmonary disease has not been definitively shown. Anti-inflammatory interventions aimed toward tempering muscle wasting and weakness in chronic obstructive pulmonary disease may not prove to be beneficial because of longer-term disruption of the regeneration of muscle tissue. Temporally and spatially targeted interventions aimed toward ameliorating oxidative stress, such as antioxidants, nutritional supplements, and chronic exercise training, may optimize outcomes toward maintaining muscle mass and performance.

  5. Variable gearing in pennate muscles.

    PubMed

    Azizi, Emanuel; Brainerd, Elizabeth L; Roberts, Thomas J

    2008-02-05

    Muscle fiber architecture, i.e., the physical arrangement of fibers within a muscle, is an important determinant of a muscle's mechanical function. In pennate muscles, fibers are oriented at an angle to the muscle's line of action and rotate as they shorten, becoming more oblique such that the fraction of force directed along the muscle's line of action decreases throughout a contraction. Fiber rotation decreases a muscle's output force but increases output velocity by allowing the muscle to function at a higher gear ratio (muscle velocity/fiber velocity). The magnitude of fiber rotation, and therefore gear ratio, depends on how the muscle changes shape in the dimensions orthogonal to the muscle's line of action. Here, we show that gear ratio is not fixed for a given muscle but decreases significantly with the force of contraction (P < 0.0001). We find that dynamic muscle-shape changes promote fiber rotation at low forces and resist fiber rotation at high forces. As a result, gearing varies automatically with the load, to favor velocity output during low-load contractions and force output for contractions against high loads. Therefore, muscle-shape changes act as an automatic transmission system allowing a pennate muscle to shift from a high gear during rapid contractions to low gear during forceful contractions. These results suggest that variable gearing in pennate muscles provides a mechanism to modulate muscle performance during mechanically diverse functions.

  6. Artificial muscle: the human chimera is the future.

    PubMed

    Tozzi, P

    2011-12-14

    Severe heart failure and cerebral stroke are broadly associated with the impairment of muscular function that conventional treatments struggle to restore. New technologies enable the construction of "smart" materials that could be of great help in treating diseases where the main problem is muscle weakness. These materials "behave" similarly to biological systems, because the material directly converts energy, for example electrical energy into movement. The extension and contraction occur silently like in natural muscles. The real challenge is to transfer this amazing technology into devices that restore or replace the mechanical function of failing muscle. Cardiac assist devices based on artificial muscle technology could envelope a weak heart and temporarily improve its systolic function, or, if placed on top of the atrium, restore the atrial kick in chronic atrial fibrillation. Artificial sphincters could be used to treat urinary incontinence after prostatectomy or faecal incontinence associated with stomas. Artificial muscles can restore the ability of patients with facial paralysis due to stroke or nerve injury to blink. Smart materials could be used to construct an artificial oesophagus including peristaltic movement and lower oesophageal sphincter function to replace the diseased oesophagus thereby avoiding the need for laparotomy to mobilise stomach or intestine. In conclusion, in the near future, smart devices will integrate with the human body to fill functional gaps due to organ failure, and so create a human chimera.

  7. The weak measurement process and the weak value of spin for metastable helium 23S1

    NASA Astrophysics Data System (ADS)

    Monachello, Vincenzo; Barker, Peter; Flack, Robert; Hiley, Basil

    2016-05-01

    An experiment is being designed and constructed in order to measure the weak value of spin for an atomic system. The principle of the ``weak measurement'' process was first proposed by Aharonov, Albert and Vaidman, and describes a scenario in which a system is weakly coupled to a pointer between well-defined pre- and post-selected states. This experiment will utilise a pulsed supersonic beam of spin-1 metastable Helium (He*) atoms in the 23S1 state. The spin of the pre-selected He* atoms will be weakly coupled to its centre-of-mass. During its flight, the atomic beam will be prepared in a desired quantum state and travel through two inhomogeneous magnets (weak and strong) which both comprise the ``weak measurement'' process. The deviation of the post-selected ms = + 1 state as measured using a micro-channel plate, phosphor screen and CCD camera setup will allow for the determination of the weak value of spin. This poster will report on the methods used and the experimental realisation.

  8. [Three infants with constipation and muscular weakness: infantile botulism].

    PubMed

    Thomasse, Y; Arends, J P; van der Heide, P A; Smit, L M E; van Weerden, T W; Fock, J M

    2005-04-09

    Two previously healthy infants, a boy of 10 weeks and a girl of 4 months presented with apathy and muscle weakness. A third previously healthy child, a girl of 6 weeks old was admitted with respiratory insufficiency. None of the three had had a bowel movement for a number of days. After extensive investigations which revealed few abnormalities Clostridium botulinum toxin was obtained in serum from all three children. Type-B-toxin was shown in the faeces of the older girl and boy; both recovered quickly. The other girl had type-A toxin; she died. Two of the three children were given honey to comfort them. Infantile botulism must be considered in every infant with symptoms of constipation and hypotonia. The diagnosis can quickly be confirmed by electromyography with repetitive 50-Hz-stimulation. Honey is a well-known source of the C. botulinum spore and should not be given to children under the age of 12 months. These three children are the first cases to be described in the Netherlands.

  9. Strength of a weak bond connecting flexible polymer chains.

    PubMed Central

    Evans, E; Ritchie, K

    1999-01-01

    Bond dissociation under steadily rising force occurs most frequently at a time governed by the rate of loading (Evans and Ritchie, 1997 Biophys. J. 72:1541-1555). Multiplied by the loading rate, the breakage time specifies the force for most frequent failure (called bond strength) that obeys the same dependence on loading rate. The spectrum of bond strength versus log(loading rate) provides an image of the energy landscape traversed in the course of unbonding. However, when a weak bond is connected to very compliant elements like long polymers, the load applied to the bond does not rise steadily under constant pulling speed. Because of nonsteady loading, the most frequent breakage force can differ significantly from that of a bond loaded at constant rate through stiff linkages. Using generic models for wormlike and freely jointed chains, we have analyzed the kinetic process of failure for a bond loaded by pulling the polymer linkages at constant speed. We find that when linked by either type of polymer chain, a bond is likely to fail at lower force under steady separation than through stiff linkages. Quite unexpectedly, a discontinuous jump can occur in bond strength at slow separation speed in the case of long polymer linkages. We demonstrate that the predictions of strength versus log(loading rate) can rationalize conflicting results obtained recently for unfolding Ig domains along muscle titin with different force techniques. PMID:10233061

  10. Weak Gravitatational Lensing by Illustris-1 Galaxies

    NASA Astrophysics Data System (ADS)

    Brainerd, Tereasa G.; Koh, Patrick H.

    2016-06-01

    We compute the weak gravitational lensing signal of isolated, central galaxies obtained from the z=0.5 timestep of the ΛCDM Illustris-1 simulation. The galaxies have stellar masses ranging from 9.5 ≤ log10(M*/Msun) ≤ 11.0 and are located outside cluster and rich group environments. Although there is local substructure present in the form of small, luminous satellite galaxies, the central galaxies are the dominant objects within the virial radii (r200), and each central galaxy is at least 5 times brighter than any other luminous galaxy within the friends-of-friends halo. We compute the weak lensing signal within projected radii 0.05 < rp/r200 < 1.5 and investigate the degree to which the weak lensing signal is anisotropic. Since CDM halos are non-spherical, the weak lensing signal is expected to be anisotropic; however, the degree of anisotropy that is observed depends upon the symmetry axes that are used to define the geometry. The anisotropy is expected to be maximized when the major axis of the projected dark matter mass distribution is used to define the geomety. In practice in the observed universe, one must necessarily use the projected distribution of the luminous mass to define the geometry. If mass and light are not well-aligned, this results in a suppression of the weak lensing anistropy. Our initial analysis shows that the ellipticity of the projected dark matter halo is uncorrelated with the ellipticity of the projected stellar mass. That is ɛhalo ≠ f × ɛlight, where f is a constant multiplicative factor. In addition, in projection on the sky, the major axis of the dark matter mass is offset from that of the stellar mass by ˜40o on average. On scales rp ≤ 0.15 r200, the weak lensing anisotropy obtained when using the stellar mass to define the geometry is of order 7% and agrees well with the anisotropy obtained when using the dark matter mass to define the geometry. On scales rp ˜ r200, the anisotropy obtained when using the stellar mass to

  11. Weak gravitational lensing theory and data analysis

    NASA Astrophysics Data System (ADS)

    Hirata, Christopher Michael

    2005-12-01

    This thesis describes methodology for analysis of weak gravitational lensing data. Weak lensing, i.e. the perturbative distortion of the images of distant objects by the gravitational deflection of light, is an important tool for understanding the distribution of matter in the universe. This is interesting because a number of extentions to the standard cosmological model, including dynamical dark energy and neutrino masses, affect the growth of structure and hence may be detectable using weak lensing. Studies of weak lensing are also motivated by lensing's ability to affect the modes in the cosmic microwave background (CMB) polarization that are sensitive to primordial gravitational waves. Both lensing of galaxies and lensing of the CMB are considered here. The section devoted to galaxies is principally concerned with measuring the lensing-induced shape distortions from galaxy images in the Sloan Digital Sky Survey (SDSS), although the methodology will be applicable to future projects. We investigate in detail the problem of separating lensing from other shape distortions such as those induced by the atmosphere, the telescope, and photon Poisson noise. Since the intrinsic shapes of observed galaxies are not known, weak lensing observations always attempt some sort of statistical averaging over galaxies that presumably have independent orientations. We investigate the extent to which this process "averages down" the intrinsic shapes and identify a new type of bias that can affect the weak lensing power spectrum. Selection biases are considered and their importance in SDSS estimated. We present some recent cosmological results using the SDSS analysis, including new upper limits on the neutrino mass. Lensing of the CMB has not yet been detected, nevertheless several experiments are being built that should have the sensitivity to see it. The statistical problem of extracting lensing information from the distortion of the CMB anisotropy is considered, and in the case of

  12. The vestibular system does not modulate fusimotor drive to muscle spindles in contracting leg muscles of seated subjects.

    PubMed

    Bent, L R; Sander, M; Bolton, P S; Macefield, V G

    2013-06-01

    We previously showed that sinusoidal galvanic vestibular stimulation (GVS) does not modulate the firing of spontaneously active muscle spindles in relaxed human leg muscles. However, given that there is little, if any, fusimotor drive to relaxed human muscles, we tested the hypothesis that vestibular modulation of muscle spindles becomes apparent during volitional contractions at levels that engage the fusimotor system. Unitary recordings were made from 28 muscle spindle afferents via tungsten microelectrodes inserted percutaneously into the common peroneal nerve of seated awake human subjects. Twenty-one of the spindle afferents were spontaneously active at rest and each increased its firing rate during a weak static contraction; seven were silent at rest and were recruited during the contraction. Sinusoidal bipolar binaural galvanic vestibular stimulation (±2 mA, 100 cycles) was applied to the mastoid processes at 0.8 Hz. This continuous stimulation produced a sustained illusion of "rocking in a boat" or "swinging in a hammock" but no entrainment of EMG. Despite these robust vestibular illusions, none of the fusimotor-driven muscle spindles exhibited phase-locked modulation of firing during sinusoidal GVS. We conclude that this dynamic vestibular input was not sufficient to modulate the firing of fusimotor neurones recruited during a voluntary steady-state contraction, arguing against a significant role of the vestibular system in adjusting the sensitivity of muscle spindles via fusimotor neurones.

  13. Painf