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Biomedical subjects

C L Richards

Publications and source records attributed to C L Richards.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characteristics of the electromyographic patterns of lower limb muscles during gait in patients with Parkinson's disease when OFF and ON L-Dopa treatment.

The purpose of this study was to compare the electromyographic (EMG) behavior of the triceps surae (TS), tibialis anterior (TA), quadriceps and hamstring muscles of the lower limbs during self-initiated free gait in a group of patients (n = 15) with Parkinson's disease (PD), when OFF and ON L-Dopa, with that of normal controls. When OFF L-Dopa, we observed qualitative disturbances in muscle activation patterns, such as an absence or extreme reduction in TA activations in early stance or during the early and late swing phases. Other disturbances included flatter profiles of the TS activation burst at push off, and temporal alterations that included prolonged activation of the proximal muscles during the stance phase. Statistical analysis showed that the TA was the most affected muscle in most of the patients particularly during the activation burst in late swing (p < .0004). After medication (ON L-Dopa), the amplitude and timing of distal muscle activations became more similar to normal values, with the increase in EMG amplitude being dramatic in some patients. In the proximal muscles, the effects on EMG amplitude were less marked and prolonged activation often persisted even after the administration of L-Dopa.

Adult↗
PubMed1997

Viscoelastic behavior of plantar flexor muscle-tendon unit at rest.

Muscle stretching as an exercise routine is widely used in orthopaedic and neurological rehabilitation. However, the muscle response to specific stretching parameters is still unclear. The aim of this study was to investigate the effect parameters, such as stretch velocity, stretch extent, and initial muscle-tendon resistance, on the plantar flexor response to passive movement. Eighteen healthy subjects (23-41 years) participated in this study. Five passive ankle dorsiflexions were randomly imposed at various velocities from 5 degrees/sec to 180 degrees/sec using a Kin-Com dynamometer, while unwanted activations of the soleus and tibialis anterior muscles were detected with surface electrodes. The resistive torque was averaged at -10 degrees and 0 degree of dorsiflexion. As shown by analyses of variance followed by Scheffé post hoc procedures, the resistive torque was significantly increased (p < 0.01) between 5 degrees/sec and higher velocities (60 degrees/sec or 120 degrees/sec and higher). A strong linear resistive torque-velocity relationship was also observed, as indicated by Pearson correlation coefficients of 0.92 (-10 degrees) and 0.91 (0 degree). The absolute resistive torque increment, calculated at 180 degrees/sec, was larger at 0 degree of dorsiflexion than at the -10 degrees of dorsiflexion position. Finally, subjects with larger initial plantar flexor resistance had a higher resistive torque increment (p < 0.05) at a high velocity of stretch (180 degrees/sec) than those with less initial muscle-tendon resistance. These results indicate that 1) the nonreflex resistive torque response to stretch is velocity-sensitive and 2) both a larger stretch extent and muscle initial resistance lead to greater resistive torque increments at high velocity. These observations suggest that slow and gradual stretching procedures, rather than rapid or ballistic movements, should be used, especially with stiff muscles to reduce the chance of injury from excessively high tension.

Adult↗
PubMed1996

Cowpox virus genome encodes a second soluble homologue of cellular TNF receptors, distinct from CrmB, that binds TNF but not LT alpha.

We show the cowpox genome (Brighton Red strain) contains a single copy gene, crmC, expressed at late times during viral infection, encoding a soluble, secreted protein whose sequence marks it as a new member of the TNF receptor family. The cysteine-rich protein contains 186 amino acids, the N-terminal 21 of which constitute a signal peptide, and two potential N-linked glycosylation sites. The approximately 25-kDa recombinant protein binds TNF specifically and completely inhibits TNF-mediated cytolysis. The strongest sequence homologues are the ligand-binding regions of the type II cellular TNF receptor (TNFRII) and CrmB, a distinct pox virus gene also encoding a soluble TNF binding protein. Unlike TNFRII and CrmB, CrmC does not bind lymphotoxin (LT alpha, TNF beta) and lacks the conserved (but nonhomologous) approximately 150-residue C-terminal domain of CrmB proteins. The presumed function of CrmC is viral inhibition of host-elicited TNF.

Amino Acid Sequence↗
PubMed1996

Correlation between the gross motor function measure scores and gait spatiotemporal measures in children with neurological impairments.

Twenty six children with a diagnosis of cerebral palsy and four with a diagnosis of head injury, aged between 1 and 8 years, participated in this study, undertaken to determine the relation between spatiotemporal measures (STM) of gait (velocity, cadence, stride length, and cycle duration) and the results of a standardized clinical test of motor function. STM were assessed by a clinical videographic gait test (VGT) whereas the Gross Motor Function Measure (GMFM) was used to assess motor function. For the total group of children, significant linear relations (r = 0.91, r = 0.93; p < 0.0001) were obtained between gait velocity and the GMFM sections D and E which include gait-related activities. These indicate that velocity is a parameter capable of reflecting functional locomotor behavior of these children. The results suggest that GMFM sections D and E may be used as locomotor predictors. The effect of walking with or without support was also investigated. The correlation between gait velocity and the GMFM(E) score was higher (r = 0.69) in the group of children walking with support than in those walking without (r = 0.35). The first group were younger and walked at velocities under 45 cm/s whereas children walking without support were older and walked at velocities ranging from 55 to 110 cm/s. These results suggest that the GMFM(E) score becomes less discriminant at gait velocities above 45 cm/s.

Cerebral Palsy↗
PubMed1995

Biomechanical analysis of swing-through gait in paraplegic and non-disabled individuals.

The purpose of this study was to determine if the deficit of motor function affects the displacement of the lower limbs and increases the physical strain of upper-body musculature in paraplegic individuals performing swing-through gait. A biomechanical model consisting of four linked rigid bodies was developed to analyze this type of gait. Data were obtained on the spatio-temporal characteristics, kinematics and kinetics from a sample of eight non-disabled and nine paraplegic individuals performing swing-through gait. Net muscle moments acting on the segments and mechanical powers at three joints (shoulder, elbow, hip) were estimated during a complete gait cycle from basic force equations and moments of force acting on a rigid body. Results show that the two groups selected a similar comfortable speed suggesting that the type of gait per se is an important factor in the selection of speed. Paraplegic individuals had a longer crutch stance phase duration than the non-disabled due to inadequate hip muscle activations as confirmed by the moment of force and power analyses. Moreover, a higher moment of force at the shoulder was observed in the paraplegics individuals, mostly during the crutch stance phase. Consequently, the loss of motor function of the lower limbs in paraplegic individuals modifies the biomechanical pattern of swing-through gait compared to non-disabled individuals, and seems to increase the physiological demand on the upper limbs during the stance and swing phases of the gait cycle.

Acceleration↗
PubMed1995

Use of a hand-held dynamometer and a Kin-Com dynamometer for evaluating spastic hypertonia in children: a reliability study.

BACKGROUND AND PURPOSE: Studies in subjects with spastic hypertonia indicate that the higher resistance to stretch in the spastic muscles is not only due to hyperactive stretch reflexes but also to changes in the muscle-tendon unit (nonreflex components). The aim of this study was to compare the test-retest reliability of two methods: hand-held dynamometry and isokinetic dynamometry for the evaluation of nonreflex and reflex-mediated resistive force in the plantar flexors of young children with spastic cerebral palsy (CP). SUBJECTS: Ten children 2 to 7 years of age with a diagnosis of spastic CP (either diplegia [n = 7] or hemiplegia [n = 3]) participated in the study. METHODS: The resistive force recorded at 0 degrees of dorsiflexion during passive ankle dorsiflexions executed at low and high velocities was evaluated twice at a 1-month interval with a Penny and Giles myometer (a hand-held dynamometer) and a Kin-Com dynamometer. The electromyographic activity of the soleus and tibialis anterior muscles was recorded during Kin-Com testing to detect unwanted activity during low-velocity tests and to identify trials with a reflex response during high-velocity tests. RESULTS: High intraclass correlation coefficients (ICCs) for the resistive force values recorded at the test and retest were computed for both the myometer (ICCs = .79 and .90) and the Kin-Com (ICCs = .84 and .84) at low and high velocities, respectively. Coefficients of variation for force values measured at a 1-month interval at low and high velocities were 13.9% and 13.2% with the myometer and 11.8% and 12.8% with the Kin-Com. CONCLUSION AND DISCUSSION: The results suggest that the myometer can provide a measure of spastic hypertonia with a reproducibility and a variation in the measures that compare to those of a computer-controlled dynamometer. From a clinical point of view, the myometer is simpler and cheaper to use given the lower cost and the little time required for testing and data analysis. Care must be taken to select a velocity that is low enough not to evoke a stretch reflex (to isolate nonreflex components) and another that is high enough to elicit a reflex response, so that it becomes possible to differentiate the reflex and non-reflex components involved in spasticity. Such a distinction is important for the choice of treatment procedures.

Ankle Joint↗
PubMed1994

Quantitative immunoblot detection of rare proteins in whole cell extracts using biotin-strepavidin reagents.

A novel immunoblotting method designed for quantitative detection of low copy-number proteins in crude cell extracts is presented. This technique can be used with either mono- or poly-clonal antibodies and utilizes the sensitivity and amplification of the high affinity interaction between biotin and strepavidin. Radioactive iodination of the strepavidin moiety allows for rapid and accurate quantification of proteins bound to nitrocellulose. This biotin/125I-strepavidin technique is highly reproducible and can detect as little as 1 ng of protein. In addition, use of biotinylated secondary antibodies directed against a specific type of primary antibody avoids the problem of low affinity recognition of immunoglobulins from certain species by protein A. Finally, the methodology is simple and convenient, and secondary and tertiary reagents are commercially available. The application of this technique is illustrated in the determination of relative quantities of the tight junction-associated protein ZO-1, present in very small amounts in epithelial cells. This same technique can also be used for the quantitative analysis of relatively more abundant cellular constituents or purified protein.

Animals↗
PubMed1994

Hip-spine movement interaction and muscle activation patterns during sagittal trunk movements in low back pain patients.

Profiles of hip-spine movement interaction and muscle activations were characterized in 10 low back pain patients and in 10 normal subjects during trunk forward bending and extension. Electrogoniometric recordings showed that patients performed the movements significantly more slowly than normal subjects when asked to choose a comfortable cadence. For movements performed at the same velocity and amplitude, only the movement profiles at the spine and activation patterns of the erector spinae (ES) muscle during flexion were found to be significantly different between the two groups. A detailed analysis revealed that a subgroup of six patients (SG2) with an abnormal hip-spine movement interaction showed a significant (P < 0.01) lack of relaxation in ES muscle at the end of flexion. Patients from SG2 had pain for a longer time (P < 0.01) compared to patients from SG1 with normal movement and electromyographic profiles. Given the small sample size, these results are not conclusive, but they suggest that the lack of relaxation of the ES muscle may be associated with perturbation of movement patterns and the duration of the symptoms.

Adult↗
PubMed1994

Early and intensive physiotherapy accelerates recovery postarthroscopic meniscectomy: results of a randomized controlled study.

The efficacy of an early, intensive, supervised rehabilitation program to accelerate knee strength recovery in the first 3 weeks postmeniscectomy by arthroscopy was evaluated using a randomized controlled trial design. The maximal voluntary isokinetic strength of 31 men, randomly allocated to either a treatment (EXP) or a control (CTL) group, was measured twice by a blind rater: preoperatively (pretest) and 3 weeks postsurgery (posttest), using a computer-controlled Kin-Com dynamometer (Chattecx Corporation, Chattanooga, TN). Strength deficits of the operated leg at the pretest and posttest were established in percent of the values obtained for the sound leg at the pretest. In the interval between the surgery and the posttest, the patients of the EXP group (n = 15) received nine supervised treatments combined to home exercises whereas patients of the control group (n = 16) had no specific physiotherapy treatment but were given instructions in postsurgical management and prescribed exercises by the orthopedic surgeons. Patients of the EXP group had better knee extensor strength recovery than patients of the CTL group (ANCOVA, p < 0.001). The size of the strength difference (3 weeks postsurgery) between EXP and CTL subgroups (n = 8) matched according to preoperative deficits was as large as 26% and the residual deficits of the untreated patients were two to three times larger than those of the treated patients. The results of this study highlight the importance of instituting an early intensive and supervised rehabilitation program, especially for workers returning to a strenuous job requiring good knee extensor muscle function.

Activities of Daily Living↗
PubMed1993

Task-specific physical therapy for optimization of gait recovery in acute stroke patients.

A randomized controlled pilot trial was conducted to estimate the effects of early, intensive, gait-focused physical therapy on ambulatory ability in acute, stroke patients. Twenty-seven patients with middle cerebral artery infarct of thromboembolic origin confirmed by computed axial tomography scan were stratified and randomly assigned to the experimental group, to a control group that received early, intensive and conventional therapy, or to a group receiving routine conventional therapy that started later and was not intense. Assessments at entry, six weeks, and three and six months by independent evaluators permitted comparisons with reference to clinical measures of motor performance, balance, and functional capacity, and laboratory measures of gait movements. Group results at six weeks demonstrated that gait velocity was similar in the two conventional groups thereby eliminating the timing of the interventions as an important factor. At that point, gait velocity was faster in the experimental group. The difference translated into a moderate effect size of 0.58. The time dedicated to gait training but not to total therapy time was correlated (rs = 0.63) to gait velocity. This effect disappeared at three and six months after stroke. These pilot results justify planning a large trial to test the effectiveness of a therapeutic protocol that focuses on early and intense gait therapy in an effort to facilitate early ambulation following stroke.

Adult↗
PubMed1993

Motor recovery after arthroscopic partial meniscectomy. Analyses of gait and the ascent and descent of stairs.

We studied motor recovery as shown by locomotor activities after arthroscopic partial medial meniscectomies in seventeen men who were twenty-five to forty-nine years old. The patients were evaluated before the operation and two, four, and eight weeks after the operation. Control values were obtained from twenty-two healthy men whose ages, weights, and heights were similar to those of the patients who had had a meniscectomy. Motion of the hip, knee, and ankle in the sagittal plane and the electromyographic activities (as measured with surface electrodes) in five muscles were recorded while each subject walked on a level walkway and then ascended and descended stairs at free speeds. The results showed that meniscal tears affect the motor-control mechanisms involved in the submaximum locomotor activities that were studied and that these abnormalities may persist for as long as eight weeks after a meniscectomy.

Adult↗
PubMed1993

Impact of knee extensor strength deficits on stair ascent performance in patients after medial meniscectomy.

After arthroscopic meniscectomy the relationship between the magnitude of knee extensor strength deficits and locomotor performance during stair ascent unloaded and when carrying a 22 kg load has been tested in 31 patients. The specific locomotor adaptations related to large strength deficits were also studied. The results indicate that large deficits were significantly associated to: 1) reduced activation of the knee extensor muscles (vastus medialis and lateralis) during the first double leg support and single leg support phases, and of the hip extensors (medial hamstrings) during the second double leg support of stair ascent, 2) overactivations of the hip extensors (gluteus maximus and medial hamstrings) during single leg support, and 3) longer cycle and step durations and lower cadences. Locomotor abnormalities in movements and muscle activations were generally found in patients with strength deficits greater than 25% while patients with smaller strength deficits (less than 25%) usually could climb stairs with normal performance. These results support the use of knee extensor strength measures to predict locomotor capacities, and also highlight the importance of postoperative knee strength rehabilitation.

Adaptation, Physiological↗
PubMed1993

Spinal cord of the rat contains more lipoprotein lipase than other brain regions.

Lipoprotein lipase (LPL) is important for the delivery of triglyceride fatty acids (TGFA) to a variety of tissues. We have used measurements of heparin-releasable LPL activity, immunohistochemistry, in situ hybridization, and Northern analysis to more fully characterize the location of LPL within the entire central nervous system (CNS) of the rat. Surprisingly, the levels of LPL activity and mRNA in the caudal spinal cord were 5- to 10-times higher than those found in any other area of the brain, levels similar to those found in adipose tissue or skeletal muscle. A number of cell types including neurons in the hippocampus, Purkinje cells of the cerebellum, and cells deep within the cortex were identified as sources of LPL mRNA. LPL protein was found within many vascular structures throughout the CNS, and within Purkinje cells. The strongest immunostaining was around nerve rootlets associated with the caudal spinal cord. Feeding studies were carried out with [14C]oleic acid to see whether CNS LPL functioned in the uptake of TGFA. These studies demonstrated uptake of chylomicron triglyceride fatty acids throughout the CNS. The localization of LPL within these structures suggests that the uptake of triglyceride fatty acids is an integral part of normal lipid metabolism of the central nervous system and may be important in regulating feeding behavior and/or maintaining normal neuronal function.

Animals↗
PubMed1992

Human myoblast transplantation: preliminary results of 4 cases.

Myoblasts from immunocompatible donors have been transplanted into the muscles (tibialis anterior, biceps brachii, and/or extensor carpi radialis longus) of 4 Duchenne patients in the advanced stages of the disease. Although no immunosuppressive treatment was used, none of the patients showed any clinical signs of rejection such as fever, redness, and inflammation. One patient transiently produced antibodies against the donor myoblasts as determined by cytofluorometric analysis. This patient and 2 others were shown to form antibodies against their donor's myotubes. Muscle biopsies of the injected tibialis anterior of 4 patients revealed that 80%, 75%, 25%, and 0% of the muscle fibers, respectively, showed some degree of dystrophin immunostaining. The contralateral noninjected muscles of the latter 3 patients did not contain any dystrophin positive fibers, while that of the first patient showed dystrophin expression in 16% of the fibers examined. Myoblasts were also injected into the extensor carpi radialis longus or the biceps brachii of these patients. A few months subsequent to injection, one patient was shown to have a 143% increase of strength during static wrist extension. This result must be interpreted with caution because a double-blind strength-measuring protocol was not used. Furthermore, we have noted that this change slowly decayed over time. The strength of 2 other patients was increased less remarkably (41% and 51%), while the strength of the fourth patient was unchanged.

Adolescent↗
PubMed1992

Use of an intensive task-oriented gait training program in a series of patients with acute cerebrovascular accidents.

The aims of this case report are to describe the application of an early and intensive task-oriented physical therapy program for gait relearning following stroke and to report the patients' ability to comply with the program. Ten patients, 60 to 75 years of age (mean = 69.8, SD = 7.3), with a middle cerebral artery infarct (confirmed by computerized tomography) were assigned to this special physical therapy program. Patients were treated twice a day, 5 days a week, from the eighth day after stroke for 5 consecutive weeks. To promote gait relearning, a program of early standing (using a tilt table when necessary), combined with weight-shifting exercises and feedback via a limb-load monitor as well as locomotor activities including exercises on a Kinetron and treadmill walking, was adapted for each patient's level of motor recovery. Walking on the treadmill (with a safety harness) was initiated as early as the second week after stroke in 4 patients, and all patients had started Kinetron training by the second week. Except for 1 patient, who was withdrawn from the study because of an infection, all patients showed good treatment compliance (93.6%) with the planned 50 treatments and were able to withstand a mean treatment duration of 44.8 minutes (SD = 6.3, range = 37.5-58.5), twice a day, during the first week of the program (8th to 14th day after stroke). Results from this pilot project indicate that intensive and graded locomotor activities can be very well tolerated in the early period after stroke.

Aged↗
PubMed1991

Intertrial reliability of work measurements recorded during concentric isokinetic knee extension and flexion in subjects with and without meniscal tears.

Intertrial reliability of work measurements was studied in 19 men with a partial medial meniscal tear (ME group) and in 10 men with no history of knee injury (control group). Three maximal voluntary concentric contractions of the muscles involved in knee extension (KE) and knee flexion (KF) were performed on a dynamometer at 30 degrees and 180 degrees/s using a preloading protocol. The subjects moved their legs through an arc of 90 degrees, and the work produced in the constant-velocity phase between 70 and 20 degrees of KE was computed for each trial. In ME group subjects able to perform three consecutive contractions (n = 12-14), high intertrial intraclass correlation coefficients (ICCs) were found (ICCs = .86-.92), except for KE work measurements at 180 degrees/s (ICC = .67). In the control group subjects, high ICCs were obtained for KE work measurements (ICCs = .87 and .95), whereas the low ICCs obtained for KF work measurements (ICCs = .64 and .79) increased to .86 and .93 when the first trial was removed. In both groups, a significant increase was found over the trials for KF measurements at 180 degrees/s and KE measurements at 30 degrees/s, but work measurements were shown to peak at the second trial. The results of this study suggest that the work produced on the second trial reflects a subject's maximal capacity. [Durand A, Malouin F, Richards CL, Bravo G. Intertrial reliability of work measurements recorded during concentric isokinetic knee extension and flexion in subjects with and without meniscal tears.

Adult↗
PubMed1991

Validity and reliability of a new electrogoniometer for the measurement of sagittal dorsolumbar movements.

This study was designed to determine the validity and reliability of a new electrogoniometer devised and developed for the measurement of sagittal dorsolumbar movements (T8-S1). The validity was measured in 10 normal subjects by comparison of the angle values obtained with the electrogoniometer with those obtained with the two-inclinometer method previously validated with x-ray measurements. The total range of movement was divided into 5 degree steps, and the angle value obtained with both methods was recorded at each of these steps. The testing procedure was repeated (retest) after removal and reattachment of the electrogoniometer. Because the potentiometer of the electrogoniometer measures angular changes indirectly from changes in the curvature of a flexible slat, a special individual calibration procedure was applied, and computation of the electrogoniometric angles (Ec) representing the dorsolumbar movement was made by software. Regression analysis of Ec in relation to corresponding inclinometric angles gave a slope of 1.03 and a Pearson's correlation coefficient of 0.97, indicating a high concurrent validity between the two methods. The intraclass correlation coefficient between test and retest (ICC = 0.982) confirmed the high reproducibility of the measurement procedures. The length of the slat can be changed to adapt the electrogoniometric system to different statures. Under standardized conditions, this new electrogoniometer can provide continuous measurements of sagittal dorsolumbar movements that are reproducible with an accuracy comparable to that obtained with the two-inclinometer method.

Adult↗