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Biomedical subjects

C M Wiles

Publications and source records attributed to C M Wiles.

At least 109 records · Page 6Linked to original sources
PubMed1985

Acid maltase deficiency in adults. Diagnosis and management in five cases.

Five patients with adult onset acid maltase deficiency are described. All patients had developed their initial pelvic girdle symptoms late in the second or early in the third decade and some years later developed signs of respiratory insufficiency. Typically they were tall, had weak and wasted paraspinal and gluteal muscles with lower limb weakness. All were orthopnoeic with marked diaphragmatic weakness. In all patients characteristic glycogen vacuoles were seen in peripheral blood lymphocytes. Muscle biopsy was characteristic in only 1 out of 4 cases and showed minimal or nonspecific features in 3. The diagnosis was confirmed by enzyme assay in muscle and cultured fibroblasts. Long-term domiciliary ventilatory support (25 patient-years) using a rocking bed or intermittent positive pressure respiration with a tracheostomy has allowed a return to work in all patients, with their clinical condition remaining stable.

Adult↗
PubMed1985

Effect of aminophylline on the human diaphragm.

The effect of intravenous aminophylline on the contractile function of the diaphragm was studied in four normal subjects. The contractility of the diaphragm was assessed by the measurement of transdiaphragmatic pressure (Pdi) after right phrenic nerve stimulation at 1 Hz. Pdi was measured before and during aminophylline infusion (6 mg/kg over 30 minutes), during which therapeutic concentrations of theophylline were attained (mean 13.8 mg/l, range 8.5-20.2). The Pdi achieved was not affected by aminophylline. This result suggests that theophylline at therapeutic concentrations has little effect on the contractility of the normal human diaphragm.

Adult↗
PubMed1983

Aminophylline and fatigue of adductor pollicis in man.

1. The effect of intravenous aminophylline on the contractility of adductor pollicis has been studied in three subjects both in the fresh state and following the induction of muscle fatigue. 2. Aminophylline had no influence on the frequency-force relationship and relaxation rate of adductor pollicis in the fresh state. 3. Fatigue resulted in a selective depression of the force response to low and moderate frequencies of stimulation and a slight effect on maximum force production 10 and 35 min afterwards. 4. Aminophylline given prior to, during and/or after fatigue did not influence this selective low-frequency fatigue at 10 or 35 min. 5. Aminophylline at the concentrations obtained has no significant effect on muscle contractility or fatiguability in man.

Adult↗
PubMed1983

The measurement of muscle strength in patients with peripheral neuromuscular disorders.

The variability of voluntary isometric strength measurements has been assessed in normal subjects and patients with peripheral neuromuscular disorders. Knee extensor strength was measured in a muscle testing chair 13 times over 5 months in each of six normal subjects: coefficients of variation (CV) ranged from 4.5 to 14.0% (mean 8.5%) for individual legs in different subjects. Paired measurements of the strength of several clinically weak muscle groups were made 1-4 days apart in 20 patients using both a handheld dynamometer and the muscle chair technique: the test/retest correlation was high (r = 0.97, p less than 0.001). Visual biofeedback did not affect the strength recorded in most cases. Each of five patients had the strength of six or seven clinically weak muscle groups measured by five examiners within a 24 hour period: the CV for the five examiners ranged from 3.6-27.3% (mean 12.8%). A single examiner measuring the same groups on five occasions in three patients obtained a mean CV of 8.9%. Sources of variation are analysed and it is concluded that, with certain precautions, voluntary strength measurements offer a simple, reliable and acceptable method for monitoring change in patients.

Adolescent↗
PubMed1982

The effect of temperature, ischaemia and contractile activity on the relaxation rate of human muscle.

The relaxation rate from electrically stimulated isometric contractions of human adductor pollicis has been measured during rewarming following cooling, during ischaemia and during ischaemic contractile activity. The Q10 for relaxation rate (25-37 degrees C intramuscular temperature) was estimated as 2 . 3. Relaxation rate was found to decline at a rate of 1 . 5% initial value per minute of ischaemia. Relaxation rate declined more rapidly during ischaemic contractile activity than during ischaemia alone. The rate of decline was more closely related to the force X time performed than the number of excitatory impulses. During a supramaximal 20 Hz tetanus, relaxation rate declined markedly at a time when only slight force fatigue had occurred; hence the decline could not be explained by selective fast muscle fibre fatigue. No recovery occurred during ischaemic rest following ischaemic activity but, following restoration of the circulation, recovery occurred with a half time of one minute being virtually complete at 5-7 min. Changes in relaxation rate during fatiguing contractions and recovery from them follow different time courses from muscle excitability and force production. Change in relaxation rate cannot be simply related to changes in the concentration of major energy metabolites. It is proposed that relaxation rate is related to the rate of energy turnover in the contracting muscle.

Adult↗
PubMed1982

Metabolic heat production in isometric ischaemic contractions of human adductor pollicis.

The rate of intramuscular temperature rise (dT/dt) has been measured in ischaemic isometric contractions of adductor pollicis in man as an index of the rate of energy turnover. Experiments were designed so as to compare dT/dt in contractions made at a constant force but at differing intramuscular temperatures or degrees of ischaemic fatigue. In the same experiments relaxation rate was measured. As intramuscular temperature was raised from 25 to 37 degrees C, dT/dt increased with a Q10 of 1 . 8 and was closely correlated with relaxation rate. During constant force submaximal ischaemic contractions dT/dt fell, failed to recover with ischaemic rest but did so within 10 min of restoration of the circulation. During the fatiguing contraction and recovery thereafter dT/dt was linearly correlated with relaxation rate. The results show that the rate of energy turnover at a constant force is susceptible to change in association with alteration in the contractile speed of the muscle. It is suggested that relaxation rate may be used as an index of the capacity of the muscle to liberate energy.

Adult↗
PubMed1981

Contractile function and fatigue of the respiratory muscles in man.

Ventilation depends on the proper functioning of the respiratory muscles. These muscles, like other skeletal muscles, can endure high work loads for only short time periods. The work of breathing in patients with lung disease in increased and it has therefore been argued that respiratory muscle fatigue may develop and contribute to respiratory failure. We have studied the contractile function and fatigue of the sternomastoid muscle and the diaphragm in normal subjects and found that these respiratory muscles have the same contractile properties as limb muscles. If subjected to a high load they develop similar patterns of fatigue. Studies on the sternomastoid muscle in patients with lung disease also confirmed that respiratory stress produces fatigue.

Action Potentials↗
PubMed1981

Fatigue in human metabolic myopathy.

The ability of muscle fibres to sustain force can be related to their economy of energy utilization and to their capacity to regenerate energy under the prevailing conditions (aerobic or anaerobic) of contraction. The pathophysiology of muscle fatigue is analysed in patients with thyroid dysfunction and with impaired glycogenolysis, and in a patient with abnormal mitochondrial function. Muscle from hypothyroid patients, like cooled muscle, is slow in relaxing and shows a reduced energy requirement (energy economy) and reduced fatiguability, whereas muscle of hyperthyroid patients may show the opposite features. In myophosphorylase deficiency the energy economy is normal in the fresh state and increases as contraction proceeds; however, fatigue is premature and associated with impaired excitation rather than an overall depletion of energy stores. With abnormal mitochondrial function the muscle tends to be effectively anaerobic and fatigue is associated with impaired excitation-contraction coupling. This appears to result from either muscle ischaemia or the dominant use of anaerobic metabolism for energy regeneration. Fatigue in these disorders of energy metabolism may ultimately be due to a reduced supply of ATP but direct evidence of this is lacking and, if it occurs, its physiological expression is probably variable.

Adenosine Triphosphate↗
PubMed1981

Aspergillus granuloma of the trigeminal ganglion.

A patient is described with aspergillus flavus granuloma of the trigeminal ganglion. The patient was effectively treated by surgical excision of most of the infected tissue followed by intensive chemotherapy with amphotericin B and flucytosine.

Adult↗
PubMed1980

Sternomastoid muscle function and fatigue in man.

1. A technique has been devised to measure the effect of stimulation frequency on the contraction force in an accessory muscle of respiration, the sternomastoid, in man. The frequency/force curve was found to be very similar to that of the quadriceps and adductor pollicis muscles. 2. Fatigue of the sternomastoid due to inspiratory loading or sustained maximum voluntary ventilation resulted in reduced force generation at low stimulation frequencies compared with maximum force. This type of fatigue frequently persisted for several hours. 3. If low frequency fatigue were to develop in patients with pulmonary disease it could have important consequences for the development of respiratory failure.

Electric Stimulation↗
PubMed1979

Relaxation rate of constituent muscle-fibre types in human quadriceps.

1. Muscle fibres may be subdivided into type I (with slow-twitch contractile properties) and type II (fast-twitch) depending on their myosin adenosine triphosphatase activity. In voluntary isometric contractions type I fibres are utilized at low forces (less than 20% of maximum) whereas type II fibres are recruited in addition at high forces. This physiological recruitment order has enabled us to measure the relaxtion rate of type I and II fibres in vivo in normal human subjects. 2. Relaxation rate was measured in 16 subjects from low (10% of maximum) and maximum isometric quadriceps contractions and the muscle-fibre type composition determined from needle-biopsy specimens in 10 subjects. The relaxation rate of type II fibres was calculated to be twice as fast as that of type I. 3. It was not possible to estimate, from studies in 33 quadriceps muscles (25 normal subjects), the contribution of type II fibres to overall fibre area from the relaxation rate as determined from electrically stimulated isometric contractions.

Adenosine Triphosphatases↗