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Biomedical subjects

W M Fowler

Publications and source records attributed to W M Fowler.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of phrenic nerve and pulmonary function in hereditary motor and sensory neuropathy, type I.

Phrenic nerve and diaphragmatic dysfunction has been assumed to be the cause of respiratory failure in hereditary motor and sensory neuropathy, type 1 (HMSN I). In order to determine the relationship between phrenic nerve and pulmonary function in this disease, 25 patients underwent a 4-step evaluation process consisting of: (1) bilateral phrenic nerve conduction study; (2) median, peroneal, and tibial motor conduction studies; (3) measurement of forced vital capacity (FVC) and maximal inspiratory and expiratory pressures (MIP, MEP); and (4) pulmonary-focused history and physical. Phrenic nerve motor latency was abnormally prolonged in 22 of the 23 (96%) subjects when a response was obtained. All had slowed velocity or absent peripheral motor conduction responses. Vital capacity was abnormally reduced in 6 of the 25 (24%) subjects. Eight (32%) had an abnormally reduced MIP, while 19 (76%) had an abnormally reduced MEP. Only 2 (8%) subjects had clinical evidence of pulmonary dysfunction. None of the dependent variables (FVC, MIP, MEP, peripheral nerve conduction, or clinical examination) correlated with phrenic nerve latencies. Although phrenic nerve latencies are markedly prolonged in HMSN I, these values are not useful in predicting respiratory dysfunction.

Adult↗
PubMed1992

Fast and slow skeletal muscles: effect of ethanol on contractility of muscles from mice.

We examined in vitro the effect of ethanol at four concentrations (0g%, 0.1g%, 0.2g%, and 0.4g%) on contractile parameters of 40 fast extensor digitorum longus (EDL) and 40 slow soleus muscles from healthy mice at 35C. Preparations were curarized to avoid the possible effect of ethanol on the terminal axons or skeletal neuromuscular junction. Contractile parameters measured included: (1) twitch and tetanic tension; (2) rate of tension development; (3) time to peak tension and half relaxation for twitch; (4) time to first evidence of relaxation in the tetanus; and (5) maximum rate of relaxation. The three lower concentrations of ethanol had no significant effect on muscle contractility; however, the 0.4g% dose reduced EDL twitch tension by 9%. High doses of ethanol (2.5g%) reduced the tetanic tension produced by the EDL and soleus muscles 31% and 26%, respectively. Ethanol at 2.5g% also reduced the twitch tension of the EDL and soleus by 50% and 38%, respectively. The data suggested that the 0.4g% is the highest dose of ethanol that should be used to dilute drugs in a solution that will bathe directly stimulated curarized muscle without confounding effects. In addition, it is highly unlikely that a direct effect of ethanol on muscle contractility in humans is related to an impairment in driving.

Animals↗
PubMed1992

Contractures in neuromuscular disease.

The percentage of subjects with contractures, mean maximal loss of range, and relative contracture indices are reported in 230 patients, with 11 diseases seen in a neuromuscular disease clinic during a five-year period. The highest percentage of contractures occurred in patients with Duchenne muscular dystrophy. The number of contractures was significantly greater (p less than .001) (1) in the lower than in the upper extremities; (2) in diseases considered myopathic than in those considered neuropathic; (3) in diseases that are X-linked than in those that are not; and (4) in rapidly progressive than in slowly progressive diseases.

Adolescent↗
PubMed1992

Analysis of human muscle contractility with a microcomputer-controlled stimulus and data acquisition system.

This report describes and assesses a technique to indirectly stimulate and quantify the human in vivo muscle response for clinical use. A method has been developed to isolate, stimulate, and record the flexor function of the first dorsal interosseus and first volar interosseus at the metacarpophalangeal (MCP) joint by stimulation of the ulnar nerve at the wrist. A microprocessor-based data acquisition and analysis system was built to deliver the electric stimulus and convert the muscle action potential (M-wave) and force measurements into digital form for analysis. To evaluate the technique, the twitch, paired twitch, and tetanic contractions were analyzed in 81 normal subjects. The tension developed by the youngest subjects (14 to 19 years old) was significantly less than the tension developed by subjects in the three older groups (20 to 34 years, 35 to 50 years, and 50 to 65 years); the tensions in the older groups were not significantly different from each other. Only minor gender differences were noted. This indicates that it is necessary to use age-group controls when looking for evidence of a muscle contractile abnormality in patients with neuromuscular disorders. posttetanic potentiation of the twitch was observed in all healthy subjects, and there was no evidence of an age or gender influence. The posttetanic increase in twitch tension was not associated with a prolongation of the twitch contraction time.

Action Potentials↗
PubMed1992

In vivo quantification of muscle contractility in humans: healthy subjects and patients with myotonic muscular dystrophy.

The purpose of this study was to use direct in vivo contractility measurements to assess muscle function in patients with myotonic muscular dystrophy (MMD). The tetanic and twitch responses and several time parameters of muscle contraction were obtained from nine MMD subjects and nine able-bodied, age-matched controls. After a routine nerve conduction study, in vivo contractility measurements were obtained by stimulating the ulnar nerve at the wrist and recording the isometric flexor function of the intrinsic muscles at the metacarpophalangeal joint of the index finger. A series of single stimuli, paired stimuli, and fused tetanic stimulations were generated during a 20-minute experimental protocol. A stable tetanus was produced at 50Hz for 1.2 seconds. M-wave and contractile data were recorded at 1,000Hz by digitization of the analog signal and storage by the microcomputer. The MMD patients were weaker than controls (p less than .05), as shown by the 39% reduction in tetanic tension and 57% reduction in twitch tension. The MMD patients also had a significant impairment in relaxing their muscles as shown by the 1,100% increase in half-relaxation time after contraction, even though there was no evidence of repetitive firing after cessation of stimulus. These data show that MMD patients exhibit failure of sarcolemmal activation, altered excitation-contraction coupling mechanisms, and failure of the contractile machinery. The myotonia is due in part, to some defect in the contractile machinery; it is not solely due to failure of sarcolemmal activation.

Adolescent↗
PubMed1990

Scoliosis associated with Duchenne muscular dystrophy.

This study evaluated the age-related and ambulation-related incidence of scoliosis among boys with Duchenne muscular dystrophy (DMD) and the relationship between wheelchair dependency and scoliosis. Charts of 88 DMD boys were reviewed retrospectively. The relationships between age and both wheelchair dependency and scoliosis were graphed as cumulative distributions with increasing patient age. The relationship between ambulation status and scoliosis was analyzed with a stepwise series of chi square analyses, assuming increasing time intervals between wheelchair dependency and scoliosis. Wheelchair dependency and scoliosis were both age-related phenomena. The relationship between ambulation status and scoliosis became significant only after 3.5 years of wheelchair dependency. It should be noted that 24% of boys with scoliosis developed their curves before cessation of ambulation. While development of scoliosis among DMD boys is clearly an age-related phenomenon, its previously assumed relationship to ambulation requires reevaluation.

Adolescent↗
PubMed1990

High-repetitive submaximal treadmill exercise training: effect on normal and dystrophic mice.

Exercise as a treatment for muscular dystrophy is controversial. Whereas vigorous high-resistive exercise increases skeletal muscle degeneration in animals with neuromuscular disorders, the effect of low-intensity, high-repetitive exercise has been conflicting. The purpose of this study was to determine if low-intensity, high-repetitive exercise has a beneficial effect on dystrophic mice. Dystrophy mice and unaffected littermates were exercised daily starting at age three weeks on a treadmill (4 m/min, 18 degrees incline, 100 meters, three weeks' duration). Exercise increased the dystrophic soleus twitch tension, the rate of twitch tension development, and the rate of twitch tension relaxation by 55%, 58%, and 48%, respectively (p less than .05). The twitch:tetanus ratio increased by 57% (p less than .05). Both the soleus and the extensor digitorum longus from the exercised dystrophic mice had significantly less degeneration (as shown by reduced internal nuclei, necrosis, fiber splitting, and moth-eaten fibers) than the nonexercised dystrophic mice (p less than .05). This study suggests that exercise training programs can be beneficial or at least not result in further muscle fiber degeneration if (1) the exercise program is started early in the course of the disease; (2) submaximal high-repetitive or even high-resistive exercise is used; and (3) the histopathologic degeneration is slowly progressive or in an arrested state.

Animals↗
PubMed1989

Relationship of manual muscle testing to objective strength measurements.

This study investigates the relationship between manual muscle test scores (MMT) and quantitative isometric strength measurements (QIS). It also evaluates the implications of that relationship for design of therapeutic trials. Extension and flexion strength at the elbows, hips, and knees of 21 neuromuscular disease patients were tested a total of 26 times utilizing both MMT and QIS testing. Paired data were evaluated with Spearman ranked correlation coefficients, and then QIS was predicted from MMT using Lowess, a consistent form of nonparametric regression. Finally, the implications of the Lowess analysis for designing a therapeutic trial were evaluated. MMT and QIS measurements were significantly correlated in all movements tested. Lowess analysis yielded prediction errors ranging from 16 to 24% of QIS range. Analysis of the sample size needed for a therapeutic trial suggested that a protocol measuring MMT would require more subjects for the same level of statistical significance as a protocol measuring QIS. Since it was not possible to reliably predict QIS values from MMT scores, such conversions are not appropriate for clinical use. This inconsistent relationship between MMT and QIS carries major implications for the design of therapeutic trials. Since therapeutic trials are time consuming, expensive, and most centers do not have large numbers of individuals available, using QIS as an outcome measure is a preferable research design.

Humans↗
PubMed1989

Effect of hind-limb suspension on young and adult skeletal muscle. I. Normal mice.

The purpose of this study was to determine the effect of hind-limb suspension (HS) on morphometric, histologic, and contractile characteristics of fast extensor digitorum longus (EDL) and slow soleus (SOL) twitch muscles in adult and immature mice. Hind-limb suspension for 2 weeks was used to produce atrophy in two groups of mice, ages 4 and 12 weeks, with nonsuspended animals serving as controls. Young HS mice exhibited marked decreases in SOL weight, length, cross-sectional area (CSA), twitch and tetanic tensions, and rates of tension development and relaxation, with increases in fatigue resistance. HS reduced the diameter of both type I and IIA fibers, increased the percentage of type I fibers, and decreased the percentage of type IIA fibers in both young and adult SOL. Muscle weight, length, CSA, IIA and IIB fiber areas, and maximum rate of tetanic tension development were decreased in EDL of young HS mice; fatigue resistance and EDL half-relaxation times were increased. For most parameters evaluated, slow twitch muscle was more affected than fast twitch. HS affected contractile characteristics less than morphometric or histologic parameters. Rates of tension development and relaxation were the contractile parameters most affected by HS, and the time parameters of contraction were least affected. For all measurements young mice were more affected than adult mice.

Aging↗
PubMed1989

Effect of hind-limb suspension on young and adult skeletal muscle. II. Dystrophic mice.

Disuse atrophy induced by limb immobilization reportedly protects dystrophic mouse muscle from histopathological changes. This study was conducted to determine whether disuse atrophy induced by hind-limb suspension (HS) limits the histopathology and contractile abnormalities typically observed in the dystrophic mouse. Two weeks of hind-limb suspension were applied to dystrophic mice (line 129B6F1) at two ages, 4 weeks (6 mice) and 12 weeks (8 mice). Thirty-one untreated dystrophics served as controls. In general, HS exaggerated the dystrophic signs, especially in the younger mice; it reduced animal weight, muscle weight, maximum tetanic and twitch tensions, and rates of tetanic and twitch tension development. HS further slowed the contractile properties of soleus (SOL) and extensor digitorum longus (EDL) muscles, and increased their fatigue resistance. HS reduced the size of type I and IIA fibers in the 6-week SOL and EDL, but not in the 14-week muscles. HS produced a preferential atrophy of SOL type I fibers, with a parallel increase in type IIA fibers. However, it did not alleviate the fiber size variability, degree of necrosis, central nucleation, inflammation, or muscle fibrosis in dystrophic muscles. These data demonstrate that disuse by hind-limb suspension does not prevent the histopathological deterioration or loss of muscle function in 6- and 14-week dystrophic mice.

Aging↗
PubMed1987

Rehabilitation research in neuromuscular diseases: current research activities and future research needs.

Rehabilitation management of individuals with neuromuscular disorders has been based primarily on clinical observation. Most investigations of treatment failed to follow sound clinical research techniques and were retrospective. In addition to using appropriate clinical research methodology, 2 parallel categories of research are desirable: investigations of the natural course of each disease, and studies of treatment outcomes. Prospective studies are needed of treatment interventions designed to include an adequate treatment group sample, control subjects matched for duration or severity of disease, supervised therapy sessions, an appropriate objective, valid and reliable measurement criterion against which to assess outcomes, and a double blind system.

Forecasting↗
PubMed1987

Functional ability and equipment use among patients with neuromuscular disease.

The relationship between graded functional ability of a neuromuscular disease patient and his routine daily activities remains unknown. Mobility equipment use may provide an indirect measure of routine daily activities. In this study 110 neuromuscular disease patients were evaluated for both functional grade (Brooke upper extremity and Vignos lower extremity scales) and equipment use. Although several of the Vignos and Brooke categories did not describe significant numbers of these patients, the Vignos scale was able to predict whether or not a given patient would use a wheelchair with 94% accuracy, while the Brooke scale was only 85% accurate. It was not possible to predict manual vs electric wheelchair use based on functional rating scores. Patients with proximal weakness, regardless of diagnosis, displayed a similar pattern of functional outcome and equipment use, which was significantly different from the pattern displayed by groups with distal weakness. As expected, as functional ability diminished, wheelchair use increased; however, wheelchair use began at surprisingly high functional levels. Patients generally preferred a combination of manual and electric wheelchair use.

Activities of Daily Living↗
PubMed1987

Upper vs lower extremity functional loss in neuromuscular disease.

Functional rating scales have been developed for evaluation of upper extremity (UE) and lower extremity (LE) function in Duchenne muscular dystrophy (DMD). The Vignos scale is accepted for LE function and the Brooke scale for UE evaluation. The assumption that UE functional loss parallels LE loss has never been tested. Furthermore, there are no studies examining the relationship between UE/LE strength. This study tests the hypothesis that UE/LE strength and functional losses are parallel in DMD and other neuromuscular disorders. Vignos grades, Brooke grades, and manual muscle test scores were determined for 27 patients with DMD, 10 patients with fascioscapulohumeral muscular dystrophy (FSH), 24 patients with myotonic muscular dystrophy (MMD) and 29 patients with other (Becker's dystrophy and limb-girdle syndrome) proximal myopathies (PM). Spearman correlation coefficients were calculated for UE vs LE functional grade and strength scores and subjected to significance analysis. While all correlations were statistically significantly different from zero (p less than 0.01), all were also significantly different from one (p less than 0.01), none representing perfect equivalence. Coefficients of determination indicated that a maximum of 86% (FSH) of variation in UE rank could be explained purely by observing LE rank. While there is a significant relationship between UE/LE strength and functional grade, these measurements were not found to be entirely equivalent. Therefore, while measures of lower body function or strength might be used as a substitute for UE measurements in drug trials in which global effects are expected, the two measurements are not equivalent when evaluating an individual's clinical status.

Child↗
PubMed1987

Upper extremity functional rating for patients with Duchenne muscular dystrophy.

The corresponding deterioration of upper extremity strength and functional capability with increasing age and the relationship between average strength and function were evaluated in 28 boys with Duchenne muscular dystrophy (DMD). Manual muscle testing (MMT) was used to evaluate strength and the Brooke upper extremity grading scale to rate upper extremity function. Mean MMT was found to relate to age in logarithmic fastion, ie, a 1% increase in age led to a 0.9% decrease in mean MMT. Functional grade (FG) related to age in a more complex fashion, revealing three groups based on age: under age 10, all in FG 1; between ages 10 and 13, concentration in FG 2 through 4; and over age 13, eight of ten in FG 5. Regression analysis did not contribute further useful information. Finally, mean MMT was found to be highly significantly related to FG. The plot of mean MMT against FG revealed an S-shaped curve, with rapidly rising functional grade once an average upper extremity strength of 4w was reached. The Brooke scale appears to be useful in describing upper extremity function among DMD patients, although it may reflect a three-grade rather than a six-grade discrimination capability. In describing the natural history of DMD, this scale demonstrates a pattern of rapid functional deterioration during the early adolescent years. This functional deterioration apparently takes place when the decline in strength reaches a threshold which cannot be compensated by muscle substitutions. At that time function deteriorates along a relatively rapid but undefined course.

Adolescent↗
PubMed1985

Serotonin-induced contractile and structural changes in fast and slow skeletal muscles in mice.

The effects of serotonin on the contractile properties of the soleus and extensor digitorum longus muscles in mice were studied after chronic intraperitoneal administration with and without a recovery period, and compared to contractile studies of the same muscles performed after acute administration of serotonin. A curarized in vitro preparation of both muscles was used throughout for the contractile studies. In addition, structural changes were studied in the chronic preparations. Chronic serotonin administration produced histologic changes in type 1 and 2A fibers and a reduction in twitch and tetanic tension and the rate of twitch and tetanic tension development limited to the slow (aerobic) soleus muscle. Acute in vitro administration of serotonin altered the contractile properties of both soleus and extensor digitorum longus muscles with the latter being more involved. The effects of chronic serotonin administration appear to be primarily related to ischemia while the effects of acute administration appear to be mediated by direct, nonvascular action on skeletal muscle.

Animals↗
PubMed1977

The effect of age on the nucleic acid content of slow- and fast-twitch muscle in normal and dystrophic mice and their litter mates.

RNA, DNA, and NCP content were measured in fast- and slow-twitch skeletal muscle of normal and dystrophic mice (HDM) and their littermates at ages 4 through 29 weeks. In normal and litter mate mice RNA and DNA content were far greater in the soleus than in the gastrocnemius while the RNA/DNA ratio and NCP content were greater in the gastrocnemius. In dystrophic mice, however, the differences between nuleic acid content of the 2 muscles were far less, apparently due to a proportionately higher content in the dystrophic gastrocnemius. Due to a proportionately lower ratio in the gastrocnemius, dystrophic RNA/DNA ratios for the 2 muscles were essentially the same. Age had a marked effect on the nucleic acid content of both muscles in all 3 mice types but to varying degrees. In the soleus, RNA and DNA content rapidly decreased until 9 to 10 weeks of age followed by a gradual decline. Soleus RNA/DNA ratios showed little change with age except in the HDM mice in which there was a significant overall decline. In the gastrocnemius, RNA content followed the same pattern but with a smaller decline in the younger ages. Age had no affect on DNA content in the normal gastrocnemius, but there was significant decline in the HDM gastrocnemius. RNA/DNA gastrocnemius ratios showed marked fluctuations in both normal and dystrophic mice but did not appear to be affected by age.

Age Factors↗