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Biomedical subjects

R W Gilliatt

Publications and source records attributed to R W Gilliatt.

At least 37 records · Page 2Linked to original sources
PubMed1982

Changes in peripheral nerve fibres distal to a constriction.

Continued constriction of the tibial nerve of the rabbit by a ligature was accompanied by a reduction in maximal motor conduction velocity distal to the ligature, and by a reduction in axonal and total fibre diameter. From the presence of paranodal demyelination and distal fibre degeneration in severely affected nerves, it is suggested that in some instances the change in axonal calibre was part of a progressive distal atrophy which could lead to secondary demyelination and ultimately to "dying-back" of the affected axons.

Animals↗
PubMed1980

Acute nerve compression during limb ischaemia--an experimental study.

In 6 baboons the deep peroneal nerve was compressed for 1 hr by a weighted cord laid over the leg just above the ankle. The procedure was carried out on both sides in a single experiment. On one side the whole leg was rendered ischaemic by a cuff round the thigh which was maintained for 3 or 4 hr before and during the period of nerve compression at the ankle. As judged by the severity of the conduction block at the ankle 24 hr later, and its subsequent recovery, the compressed nerves which were also made ischaemic fared no worse than those subjected to compression alone. Histological studies showed evidence of selective damage to large myelinated fibres during the compression; this damage was not increased on the ischaemic side. There is thus no evidence that ischaemia increased the susceptibility of nerve fibres to mechanical damage in these experiments.

Acute Disease↗
PubMed1979

Acute ischaemic neuropathy in the rabbit.

Ligation of either the common and internal iliac or the internal and external iliac arteries produced ischaemic lesions of the sciatic nerve and its branches, as well as direct muscle damage, in 5 out of 6 rabbits. In one animal, ligation of the aorta and of the internal iliac artery on one side produced a similar mixture of nerve and muscle damage on the side of the double ligation. Ligation of the femoral artery alone in 3 animals failed to produce significant changes. In the 6 affected animals there was paralysis of the hind leg on the side of the iliac ligations, with loss of tendon reflexes. Appreciation of pinprick over the foot and lower leg also appeared to be impaired. Complete ischaemic necrosis with irreversible damage to both neural and connective tissue elements did not occur in the main nerve trunks, but was present in some of the intramuscular nerve bundles as part of generalized coagulative necrosis of the most severely affected muscles. The characteristic pathological changes in the nerve fibres of the main nerve trunks were Wallerin degeneration and paranodal demyelination, the former being more extensive than the latter. In the animals with double iliac ligations, the upper level of ischaemic nerve damage was in the thigh, the tibial portion of the sciatic nerve being more commonly affected than the peroneal. Nerve and muscle damage tended to occur at different levels in the limb, but there was no example of clinical paresis due to neural damage without any ischaemic muscle changes being present. In two of the 3 animals in which the plantar muscles were examined, these muscles appeared to escape direct damage in spite of ischaemic lesions in the more proximal parts of the limb.

Acute Disease↗
PubMed1978

Peripheral nerve conduction in patients with a cervical rib and band.

In 14 patients with wasting of the hand due to a cervical rib and band, motor and sensory conduction studies on the peripheral parts of the median and ulnar nerves were helpful in establishing the correct diagnosis. The median nerve findings excluded carpal tunnel syndrome even when the clinical pattern of wasting in the hand suggested this diagnosis. Preservation of conduction velocity in the ulnar nerve excluded ulnar entrapment at the elbow; the reduced amplitude of the ulnar sensory action potentials (SAPs) indicated that the lesion was distal to the dorsal root ganglia. In 3 patients with ulnar SAP amplitudes that were low but not clearly abnormal, the level of the lesion was confirmed by a reduced response to intradermal injection of histamine on the inner side of the forearm.

Action Potentials↗
PubMed1978

Extrajunctional acetylcholine sensitivity of inactive muscle fibres in the baboon during prolonged nerve pressure block.

1. Nerve-evoked muscular activity was abolished in the small hand muscles of the baboon for 1-2 months by a 3 hr period of nerve compression from a pneumatic tourniquet inflated round the forearm. In the large diameter nerve fibres, this produced either a prolonged conduction block due to local myelin damage at the site of compression, or (in 10-30% of the large fibres) Wallerian degeneration. 2. At varying intervals after nerve compression the extrajunctional acetylcholine (ACh)-sensitivity of innervated but inactive muscle fibres in the fourth lumbrical muscle was measured. Observations were also made on lumbrical muscle fibres at similar intervals after surgical denervation. 3. The ACh sensitivity of nerve-blocked muscle fibres started to develop later than in denervated muscle fibres (10 vs. 7 days) and remained at a lower level (40-80 mV/nC, median ACh-sensitivity) than that of denervated muscle fibres (200-437 mV/nC) from 21 to 63 days after nerve block or denervation. 4. In stimulation experiments on four muscles, extrajunctional ACh-sensitivity of both denervated and innervated but inactive fourth lumbrical muscle fibres was reduced by muscular activity. 5. In four animals mild compression was used in the lower limb to produce persistent nerve block without Wallerian degeneration. With one exception (in which some Wallerian degeneration had occurred) recording with a co-axial needle from abductor hallucis showed no spontaneous fibrillation up to 28 days after compression, although the extrajunctional ACh-sensitivity of the muscle fibres appeared to reach levels similar to those observed in the forelimb. All four muscles developed a slight increase in insertion activity after 1-2 weeks. 6. It may be concluded that both muscular activity and some other neural influence, independent of muscular activity, are able to influence extrajunctional muscle properties in the baboon. The neural influence appears to be more effective in preventing spontaneous fibrillation than in preventing a rise in ACh sensitivity of the extrajunctional muscle membrane.

Acetylcholine↗
PubMed1977

Regeneration distal to a prolonged conduction block.

In 6 baboons a tourniquet round the knee was used to produce a prolonged local conduction block. This was followed, within a few days, by a surgical crush of the tibial or deep peroneal nerve at the ankle, in order to produce Wallerian degeneration distally. Electrophysiological recordings from small foot muscles were then used to study the time-course of regeneration in motor fibres. When the results were compared with those from crushed but unblocked nerves of the opposite leg, there was no evidence that either reinnervation of muscles or the subsequent maturation of the regenerating motor nerve fibres was delayed by the prolonged proximal conduction block.

Animals↗
PubMed1976

Axonal velocities of motor units in the hand and foot muscles of the baboon.

The axonal velocities of single motor units in the small hand and foot muscles of the baboon were studied by means of a collision technique which produced selective blocking of most of the fast-conducting fibres. In the abductor pollicis brevis muscle velocities ranged from 43 to 82 m/sec, and in the abductor digiti minimi muscle from 40 to 78 m/sec. In the extensor digitorum brevis muscle the range was 40-70 m/sec. When velocities were plotted as percentages of the maximal obtained in the same experiment, the range was similar in the 3 muscles studied. Most motor units had velocities greater than 65% of maximal but, in a few, velocities were between 55% and 65% of maximal. The possible relevance of these findings to human motor nerves is discussed.

Animals↗
PubMed1975

Sub-clinical entrapment neuropathy in man.

Twelve median and 12 ulnar nerves were obtained at routine autopsies from patients without known disease of the peripheral nervous system. Enlargement of cross-sectional area due to an increase in connective tissue elements was commonly present in the ulnar nerve at the elbow and in the median nerve under the flexor retinaculum. Renaut bodies were also prominent at these two sites. The connective tissue changes did not appear to be related to the presence or absence of nerve fibre damage. When nerve fibres were teased apart and examined individually, localised changes were found at the elbow in 5 ulnar nerves and under the flexor retinaculum in 5 median nerves. The changes were mild and transverse sections at the same levels showed few abnormalities. However, the changes were similar in character to those described previously in experimental animals with entrapment syndromes. They are therefore considered to be valid evidence of sub-clinical entrapment in apparently unaffected human subjects.

Acute Disease↗