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Biomedical subjects

A Young

Publications and source records attributed to A Young.

At least 361 records · Page 20Linked to original sources
PubMed1978

Tests of skeletal muscle function in children.

The contractile properties of a large proximal muscle (quadriceps femoris) and a small distal muscle (adductor pollicis) have been measured in normal children and children with neuromuscular disorders. The method of stimulating the quadriceps femoris to contract, previously evaluated in adults, was found to be acceptable to children. In normal children a number of indices of muscle function were found to be similar to those in adults. A small study of the function of the adductor pollicis using supramaximal stimulation of the ulnar nerve was carried out in boys with Duchenne dystrophy. Decreased contractile force and prolonged relaxation times from a tetanic stimulation were noted in both the proximal and distal muscles of the boys with Duchenne dystrophy.

Adolescent↗
PubMed1977

Order, analogy, and efficacy in Ethiopian medical divination.

An important source of the efficacy of techniques for managing sickness is their capacity for symbolically ordering the disordered states associated with disease. (The ability to give empirical proofs is another source.) This article describes the symbolic ordering wirked by a method of divination that is practiced by the Amhara of Ethiopia. Emphasis is given to indicating how order is accomplished through linking disease with phenomenological domains that are remote from the biophysical locus of sickness. The point is made that ordering and linking depend on processes of analogy.

Attitude to Health↗
PubMed1977

Human skeletal muscle function: description of tests and normal values.

1. The force produced by isometric contractions of the quadriceps muscle have been studied during maximal voluntary contractions and when a substantial part of the muscle was electrically stimulated via surface electrodes. 2. In normal children and adults, the force of a maximal voluntary contraction of the quadriceps was proportional to body weight. 3. The function of the quadriceps has been described in terms of the force/frequency curve, speed of relaxation and the rate of loss of force during 18 s stimulation at 30 Hz and 100 Hz. 4. The functional characteristics of adductor pollicis when stimulated via the ulnar nerve were essentially similar to those of the quadriceps. 5. Studies of the function of these two muscles are complementary since quadriceps femoris is amenable to needle biopsy investigations of its structure and chemistry whereas adductor pollicis is more suitable for electrophysiological studies.

Adolescent↗
PubMed1977

A study of the contractility, biochemistry and morphology of an isolated preparation of human skeletal muscle.

1. A new method of studying isolated human skeletal muscle has been evaluated. This involves the incubation and electrical stimulation of strips of muscle, obtained at surgical biopsy, that are tied at the cut ends of the fibre bundles. 2. Morphological examination showed that the fibres were sealed off at the cut ends. Damage appeared to be restricted to the areas immediately adjacent to the ties. 3. Contractile properties were well maintained for several hours and measurements of tissue metabolites showed that muscle contents of the high-energy phosphate compounds were well preserved. 4. The isolated preparations were found to have the same contractile properties as human quadriceps femoris studied in vivo by the methods described in the preceeding paper. 5. Correlation was found between the relaxation speed of the isolated preparations and their fibre-type composition histochemically determined. 6. It is concluded that this technique is a valid addition to the present methods of studying the physiology and pharmacology of human skeletal muscle.

Adenosine Triphosphate↗
PubMed1977

Functional and structural changes after disuse of human muscle.

1. Seven patients who had suffered unilateral leg fracture were studied after removal of immobilizing plaster casts. 2. Leg volume measured anthropometrically was reduced by 12% in the injured leg (5-68 +/- 1-05 litres) compared with the uninjured (6-43 +/- 0-87 litres). Associated with this loss was a similar reduction in the net maximum oxygen uptake achieved in one-leg cycling, from 1-89 +/- 0-21 1/min in the uninjured leg to 1-57 +/- 0-18 1/min in the injured. 3. Measured by a percutaneous needle biopsy technique, a reduction of 42% was found in the cross-sectional area of the muscle fibres sampled from the vastus lateralis of the injured compared with the uninjured leg. 4. Staining for myosin adenosine triphosphatase activity showed that both type I and II fibres were affected, being reduced respectively from 3410 to 1840 micronm2 and from 3810 to 2390 micronm2 cross-sectional area. 5. Possible reasons and implications are discussed for the discrepancy between the magnitude of the difference observed in the gross measurement of leg function (maximum oxygen uptake) and structure (leg volume) as compared with the cellular level (cross-sectional fibre area).

Adolescent↗
PubMed1977

Clinical investigations of muscle contractility.

The use of tests of muscle contractility based on electrically stimulated contractions means that information obtained from the more traditional tests of voluntary muscular performance and strength may be complemented by indices which are independent of volition and independent of muscle mass. Such tests are no longer limited to peripheral muscles but may now be applied to a large proximal muscle--the quadriceps femoris. This report describes the in vivo testing of a drug's pharmacological activity on the quadriceps muscle by a study of the relative forces produced by different frequencies of stimulation. It also illustrates that hypothyroidism is not the only endocrine disorder whose treatment may be monitored by measuring the speed of muscle relaxation. Finally, it describes a patient whose quadriceps weakness was explained by the demonstration of the failure of the muscle to maintain tension during prolonged stimulation.

Clinical Trials as Topic↗
PubMed1976

Glycine-specific synapses in rat spinal cord. Identification by electron microscope autoradiography.

Glycine, an inhibitory transmitter in spinal cord, is taken up into specific nerve terminals by means of a unique high-affinity uptake system. In this study, [3H]glycine was directly microinjected into rat ventral horn in vivo and electron microscope autoradiography used to localize the label in various anatomic compartments. Quantiative analysis showed that [3H]glycine labeled a high proportion of axosomatic and axodendritic synapses which presumably act to inhibit spinal motor neurons.

Animals↗
PubMed1975

Tetanus toxin: direct evidence for retrograde intraaxonal transport.

The neurotoxin tetanospasmin causes tetanus when it reaches the central nervous system. In this autoradiographic study, 125-I-labeled tetanospasmin was injected into the leg muscles of rodents, and the nerves supplying these muscles were crushed. The labeled toxin accumulated within axons on the distal side of the crush. This study provides direct evidence for retrograde axonal transport of a macromolecular toxin that acts at synapses in the central nervous system.

Animals↗