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Biomedical subjects

A R Hudson

Publications and source records attributed to A R Hudson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Histopathology of compression of the superficial radial nerve in the forearm.

A histologic assessment of the radial sensory nerve from a patient with nerve compression is reported. Histologic changes were confined to the region of the nerve compression. Connective tissue changes consisted of an increased thickness of the epineurium and perineurium. Nerve fiber changes consisted of Schwann cell pathology with marked thinning of the myelin noted in the myelinated fibers and evidence of degeneration and regeneration noted in the unmyelinated fiber population. Nerve fiber pathology was not uniform but varied from fascicle to fascicle in the compressed area.

Forearm↗
PubMed1986

A study of neurotrophism in a primate model.

This study investigated the existence of neurotrophism in a primate model. In eight adult cynomolgus monkeys the sensory component of the femoral nerve was sectioned and introduced into the proximal channel of a silicone Y chamber. The proximal stump was given distal choices of various tissues inserted into the remaining arms of the silicone Y chamber. The targets presented were combinations of tendon, muscle, intact distal nerve, distal nerve graft, or an empty silicone channel. After 6 weeks, ultrastructural analysis confirmed axonal growth toward distal nerve tissue, while minimal or no nerve regeneration was directed toward tendon, muscle, or the empty silicone channel. The results showed that either a distal nerve stump or a nerve graft will act as a specific target to the regenerating primate proximal nerve stump.

Animals↗
PubMed1986

Perineurioma: a benign peripheral nerve tumor.

A unique benign peripheral nerve tumor, called a perineurioma, is described in this report. Light and electron microscopy and immunohistochemistry indicate that this tumor was derived from the perineurial cell. We discuss the ultrastructure, histogenesis, and management of this neoplasm.

Adult↗
PubMed1986

Biomechanical study of full-contact karate contrasted with boxing.

It is known that boxers suffer a characteristic cumulative brain injury from repeated blows to the head that correlates well with the number of bouts fought. Much less is known about full-contact karate (kickboxing), which is relatively new. In full-contact karate, punches and kicks are actually landed, rather than being focused to culminate just short of an opponent, as practiced in traditional karate. Although a combatant can win on points, the surest means of victory is a knockout. Consequently, fighters strive to land blows to the head. To investigate the relative force of kicks and punches, a dummy head was mounted 175 cm above the floor (to simulate a 50th-percentile man standing erect) and 125 cm above the floor (to simulate the man in a crouched position) on a universal joint permitting motion about three axes. The mechanism was contrived to provide constant rotational stiffness, and springs provided constant restorative moments about the three axes. The texture of soft tissue was simulated by a mask of visco-elastic foamed materials. Fourteen karate experts punched and kicked the dummy. Accelerometer measurements in the 90- to 120-G range indicated that safety-chops (hand protectors) and safety-kicks (foot padding) did not reduce acceleration of the dummy. Ten-ounce boxing gloves mitigated peak acceleration to some extent. Kicks and punches produced accelerations in the same range. Violent acceleration of the head by any means produces injury. The authors conclude that, if full-contact karate is widely practiced, cases of kickboxer's encephalopathy will soon be reported.

Acceleration↗
PubMed1985

Selected recent advances in peripheral nerve injury research.

Interactions between Schwann cells and growing neurites are reviewed as are the implications of axonal transport studies in shaping the regenerative process. Increased investigative attention will be required to study biochemical changes occurring in the local environment of the injury site even though continued study of the neuronal metabolic process remains critical. Important studies concerning the connective tissue structure of nerve and probable "blood-nerve barrier" sites are reviewed. Factors responsible for connective tissue proliferation and fibroblast alignment after injury are not well understood. Recent experimental studies relating to surgical repair of nerve are reviewed as are a few selected papers reflecting changes in clinical management of the patient with nerve injury.

Axonal Transport↗
PubMed1985

Hemangioma calcificans of the spinal cord.

A 27-year-old woman presented with hemotomyelia during pregnancy. Needle drainage of the spinal cord was followed by relief of symptoms. Symptoms recurred during a second pregnancy 4 years later and she presented with an avascular mass in the midcervical spinal cord. This lesion proved to be hemangioma calcificans, a densely calcified and ossified variant of cavernous angioma.

Adult↗
PubMed1985

A primate model for chronic nerve compression.

Peripheral compression neuropathy is a common clinical entity but little human nerve material has been available for study. It has been difficult to develop an experimental model of chronic nerve compression which is reliable and reproducible, making it difficult to assess the various treatment modalities currently in use to manage this problem. In a recent study using a rat model, connective tissue and nerve fiber changes associated with chronic nerve compression were described by the authors. The present study expands this same model of chronic nerve compression to the multifascicular median nerve of the cynomolgus monkey, using this model to test whether or not current surgical treatment modalities for nerve entrapment will alter the course of chronic nerve compression. Using histologic and morphometric parameters, there did not appear to be a difference between nerves treated by decompression alone or by decompression and internal neurolysis. Total number of nerve fibers remained constant, as did axon size, but a demyelinating process was demonstrated which is a significant component of chronic nerve compression. Although the small number of experimental animals (7) makes precise evaluation of the clinical modalities impossible, the authors expect that further study of the multifascicular median nerve of the cynomolgus monkey will prove to be a useful source of future experimental evidence and will help to interpret the diverse therapeutic and operative techniques currently in use.

Animals↗
PubMed1985

The nerve allograft response--an experimental model in the rat.

The nerve allograft response in a rat model is presented. The Lewis rat (RTI1) served as the recipient animal while Fischer rats (RTI1) and ACI rats (RTIa) provided the donor nerve allografts. A Lewis/Lewis autograft group was used as the control group. Histological and electrophysiological measurements of nerve regeneration were assessed at five months. While good regeneration was noted in the autograft and matched allograft groups, regeneration across the unmatched allograft was poor. The degree of nerve regeneration (as measured with histological and electrophysiological values) correlated well with previous immunological studies and would support the use of this model for future investigation of the nerve allograft response in the rat.

Animals↗
PubMed1985

Peripheral nerve injection injury with purified bovine collagen--an experimental model in the rat.

This study investigated the effect of purified bovine collagen (Zyderm collagen implant) on peripheral nerve tissue in rats. Zyderm was injected extrafascicularly and intrafascicularly into the sciatic nerve of adult Wistar rats. The nerves were examined by light and electron microscopy and the integrity of the blood-nerve barrier assessed by protein tracer technique. With light microscopy the precise anatomical location of the injected material could be identified. The purified bovine collagen did not appear to be neurotoxic. After extrafascicular injection, only minimal nerve fiber damage was seen. Intrafascicular injection produced a histological picture compatible with compression neuropathy and was associated with a breakdown in the blood-nerve barrier.

Animals↗
PubMed1985

Histologic assessment of nerve regeneration in the rat.

This study reports the degree of spontaneous regeneration that will occur in the sciatic nerve of a rat 5 months after complete resection of the nerve. In 30 animals, the sciatic nerve was excised. Histological assessment at 5 months revealed evidence of regeneration for a variable distance (mean 23.7 mm +/- 6.4 mm). Histological sections were studied at 1-cm intervals along the length of the nerve. Evidence of compartmentation with "minifascicle" formation was noted. The orientation of the nerve fibers was parallel to the long axis of the nerve. This study assessing spontaneous regeneration is meant to serve as a control for other studies evaluating the effect of factors that may influence nerve regeneration in the rat model.

Animals↗
PubMed1985

Nerve regeneration through a pseudosynovial sheath in a primate model.

This study investigated nerve regeneration through a pseudosynovial sheath in a primate. After resecting a 3-cm segment of the ulnar nerve at the elbow, the two ends of the divided nerve were placed at either end of the pseudosynovial tube, positioning the nerve ends such that they were separated by a 3-cm gap. Histologic evaluation at 3, 5, 7, and 9 months demonstrated evidence of nerve regeneration across this gap. Nerve fiber diameter and density assessment demonstrated a maturation of the fiber pattern with time. The overall morphologic pattern of the regenerating nerve within the pseudosheath was that of multiple small fascicles, each within its own perineurial compartment. This pattern resembled neither the proximal nor distal nerve fascicular pattern.

Animals↗
PubMed1985

Alteration of neuroma formation by manipulation of its microenvironment.

In a primate model a histologic assessment of neuroma formation is reported. Three experimental groups were defined. Transected sensory nerves left adjacent to the incisional wound in an area of movement (wrist) were considered the control group. In the "proximally cut" group the same sensory nerves were positioned well proximal to the incisional wound. In the "muscle-implantation" group these nerves were placed in adjacent muscles. At 6 months a histologic assessment of the neuroma formation in the three experimental groups was carried out. Implantation of the sensory nerve into muscle significantly altered the regenerative potential of that nerve. The muscle completely surrounded the sensory nerve. The minimal neuroma that formed had significantly less scar tissue and contained nerve fibers that were of a smaller diameter and decreased density than either the control or the proximally cut group. There were no histologic differences between these latter two groups. However, regeneration into the overlying skin that was noted in the control neuromas was not seen in those nerves which had been proximally cut.

Animals↗
PubMed1985

Shoulder arthrodesis for the treatment of brachial plexus palsy.

In 14 adult patients with brachial plexus injuries, shoulder arthrodesis was completed in a position of 30 degrees abduction, 30 degrees flexion, and 30 degrees internal rotation. Abduction was measured by the position of the arm in relation to the side of the body with the scapula in the anatomic position. Internal fixation was used in each case. Six patients had had Steindler procedures. Three patients with complete paralysis were treated by above-elbow amputation. All shoulders fused. Mean follow-up time was 32 months. All patients noted that shoulder fusion had improved the function of their extremities. Minimum shoulder motion was 60 degrees abduction and 50 degrees flexion. Three procedures failed because of continued pain that was not relieved by surgery. One patient with an elbow flexion contracture disliked the combination of shoulder and elbow flexion. Seven patients required plate removal. Only one of the three patients who had had above-elbow amputation became a good prosthetic user. Shoulder arthrodesis is a reliable procedure that improves function in adult patients with brachial plexus palsy.

Adult↗
PubMed1984

Chronic nerve compression--an experimental model in the rat.

This study reports a rat model of chronic nerve compression. The sciatic nerves of adult male Sprague Dawley rats were bonded with 1-cm lengths of tubing with varying internal diameters. Histological and electrical studies as well as studies to assess the blood-nerve barrier function were carried out at one through six months. With marked compression of the sciatic nerve, profound electrical changes were noted as early as one month, and histological findings were those of degeneration and regeneration. In the rats with minimal compression, nerve conduction studies remained normal. The earliest findings were alterations in the blood-nerve barrier, followed by histological changes in the large myelinated fibers at the periphery of the fascicles and changes about the nodes of Ranvier. This model appears to be a valid one with which to study other aspects of both the pathophysiology and treatment of chronic nerve compression.

Animals↗
PubMed1984

Peripheral nerve allograft: an immunological assessment of pretreatment methods.

An in vivo immunological assay was used to determine quantitatively the nerve allograft response in a rat model. The nerve allograft was then pretreated with a number of pretreatment methods that have been used clinically and experimentally. Using the same immunological assay to determine quantitatively the nerve allograft response, we found that lyophilization and high doses of irradiation could modify the nerve allograft in such a way as to make it less immunogenetic to the host animal. The other methods of pretreatment did not alter the antigenicity of the allograft.

Animals↗
PubMed1984

Peripheral nerve injury by chymopapain injection.

Chymopapain injected into the intervertebral disc space (chemonucleolysis) has been used clinically in patients with disc disease with success. Neurosurgical complications secondary to the procedure have, however, been reported. In this study, the authors have investigated the possible neurotoxic effect of chymopapain on the peripheral nerve in rat and primate models. While the extrafascicular injection caused no nerve fiber damage, the intrafascicular injection caused dose-related nerve fiber damage in both species.

Animals↗
PubMed1984

Differences in the effects of selenite and biological selenium on the chemical form and distribution of mercury after the simultaneous administration of HgCl2 and selenium to rats.

The interaction was compared between inorganic (HgCl2) mercury and selenite (Na2SeO3) vs. the interaction between inorganic mercury and biological selenium (a freeze-dried preparation of liver from rats treated with selenite). Organ concentrations of selenium were always significantly lower after biological selenium than after selenite. Biological selenium affected the organ distribution of inorganic mercury differently than selenite. Furthermore, the speciation of mercury was affected by this form of selenium. A mercury-selenide compound (presumably HgSe) accounted for a greater proportion of total mercury in tissues after selenite than after a dose of biological selenium. Administration of selenomethionine had a similar effect on the speciation of mercury to that seen after biological selenium. As the forms of selenium in selenomethionine or selenium deposited in the liver are most likely nearer than selenite to selenium present in food, our results suggest that, as far as the reaction of mercury with selenide is concerned, experiments with selenite overestimate the protective effect of dietary selenium against inorganic mercury and possibly against methylmercury.

Animals↗