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Biomedical subjects

R D Fraser

Publications and source records attributed to R D Fraser.

At least 73 records · Page 4Linked to original sources
PubMed1992

Annular tears and disc degeneration in the lumbar spine. A post-mortem study of 135 discs.

We studied 135 lumbar discs from 27 spines removed post-mortem from subjects of an average age of 31.5 years. Defects of the annulus fibrosus were classified as peripheral, circumferential or radiating; the nucleus pulposus as normal, moderately or severely degenerate. Peripheral tears were more frequent in the anterior annulus, except in the L5-S1 disc. Circumferential tears were equally distributed between the anterior and the posterior annulus. Almost all the radiating tears were in the posterior annulus, and closely related to the presence of severe nuclear degeneration. Histology suggested that peripheral tears were due to trauma rather than biochemical degradation, and that they developed independently of nuclear degeneration. The association of peripheral annular lesions with low back pain is uncertain but our study suggests that they may have a role in the pathogenesis of discogenic pain.

Adolescent↗
PubMed1991

Radiologic interpretation of lumbar vertebral rotation.

The different parts of the lumbar pedicle were identified on an anteroposterior (AP) radiograph to determine reliable reference points to be used to quantify vertebral rotation. Standard AP radiographs were taken of dry lumbar vertebrae with 5 degrees increments in rotation in the transverse plane, ranging from 0 degrees to 30 degrees both to left and right. Identical sets of radiographs were taken with radiopaque markers around the middle and in the anterior and posterior parts of the pedicles. The anatomic center of the pedicle was found to lie slightly more lateral than the center of the pedicle halo. The inferior edge of the pedicle corresponded with the anterior part of the pedicle and the superior edge, with the posterior part.

Humans↗
PubMed1991

Comparison of eight psychometric instruments in unselected patients with back pain.

A comparative evaluation of eight psychometric instruments was made in 274 patients who were currently suffering or previously had suffered from low-back pain. The specificity and sensitivity values for detection of psychological disturbance were calculated and optimum cutoff scores determined for each test. The influence of current pain, social group, compensation, migrant status, and unemployment on the accuracy of each test were evaluated. The Pain Drawing, the Inappropriate Symptoms, the Inappropriate Signs, and the Illness Behavior Questionnaire were found to be least discriminating. The Modified Somatic Perception Questionnaire, the Hospital Anxiety Scale, the Hospital Depression Scale, and the Zung Depression Scale were the most accurate and least affected by the factors examined. The combination of the Modified Somatic Perception Questionnaire and the Zung Depression Scale yielded specificities and sensitivities of 91% and 84% for men and 96% and 85% for women, respectively. This combination is recommended for the assessment of psychological disturbance in patients with low-back pain.

Back Pain↗
PubMed1990

HIV antibody screening among immigrants: a cost-benefit analysis.

To assess the economic impact of HIV (human immunodeficiency virus) antibody screening among potential immigrants on Canada's health care system we estimated the costs and benefits of such screening among the 160 135 immigrants who entered Canada in 1988 using the in-hospital costs of treating AIDS (acquired immune deficiency syndrome) over the 10 years after immigration. This economic model was based on current international HIV seroprevalence data, Canadian immigration statistics and estimates of disease progression. Between 343 and 862 of the immigrants were estimated to have been HIV seropositive; with the use of the enzyme-linked immunosorbent assay and the Western blot technique 310 to 780 of them would have been correctly identified as being seropositive, and 33 to 82 would have been incorrectly classified as being seronegative. Another 16 would have been falsely classified as being seropositive. There would have been 151 to 379 cases of AIDS from 1988 to 1998 among the immigrants identified as being HIV-positive. The estimated total cost of screening would have been $3.3 to $3.4 million. The in-hospital costs of treating HIV-infected immigrants in whom AIDS developed between 1989 and 1998 would have been $5.0 to $17.1 million. Accordingly, screening would have saved $1.7 to $13.7 million over the 10 years after immigration. However, we do not advocate screening on the basis of economic analysis alone and acknowledge that any policy regarding such screening must also incorporate social, legal and ethical considerations.

Acquired Immunodeficiency Syndrome↗
PubMed1990

1990 Volvo Award in experimental studies. Anulus tears and intervertebral disc degeneration. An experimental study using an animal model.

An animal model was developed to test the hypothesis that discrete peripheral tears within the anulus lead to secondary degenerative changes in other disc components. In 21 adult sheep, a cut was made in the left anterolateral anulus of three randomly selected lumbar discs. The cut was parallel and adjacent to the inferior end-plate, and had a controlled depth of 5 mm. This left the inner third of the anulus and the nucleus pulposus intact and closely reproduced the rim Lear lesion described by Schmorl. Animals were randomly allocated to different groups in relation to the length of time interval between operation and death, varying from 1 to 18 months. At death, the lumbar spine was cut into individual joint units and each disc sectioned into six parasagittal slabs. After observation of the slabs under the dissecting microscope, two of the six slabs, the one containing the anulus lesion and a contralateral, were processed for histology. The results of this study suggest that, despite the great care taken at operation to ensure that the inner anulus was left intact, progressive failure of the inner anulus was seen in all sheep and occurred in the majority of discs between 4 and 12 months after the operation. Although the outermost anulus showed the ability to heal, the defect induced by the cut led initially to deformation and bulging of the collagen bundles, and eventually to inner extension of the tear and complete failure. These findings suggest that discrete tears of the outer anulus may have a role in the formation of concentric clefts and in accelerating the development of radiating clefts. Peripheral tears of the anulus fibrosus therefore may play an important role in the degeneration of the intervertebral joint complex.

Animals↗
PubMed1990

Molecular structure of the cell-attachment protein of reovirus: correlation of computer-processed electron micrographs with sequence-based predictions.

The receptor-recognition interaction that initiates reovirus infection is mediated by the sigma 1 protein, located at the vertices of the icosahedral virion. We have applied computer-based image-averaging techniques to electron micrographs of negatively stained preparations of sigma 1 purified from virions (serotype 2 Jones). Combining these results with inferences based on the amino acid sequence has led to a molecular model in which the overall folding of the chains is described; its conformation embodies motifs, coiled-coil alpha-helices and nodular multichain elements rich in beta-sheets, previously detected in the corresponding proteins of other viruses, but with some novel variations. Sigma 1 is a filamentous lollipop-shaped molecule with an overall length of approximately 48 nm; it has a flexible "tail," approximately 40 nm long by 4 to 6 nm wide, terminating at its distal end in a globular "head," approximately 9.5 nm in diameter. The purified protein is a tetramer (4 by 50 kilodaltons) consisting of two similarly oriented dimers bonded side by side and in register. For each chain, a cluster of hydrophobic residues at its amino terminus resides at the proximal end of the tail; next, an alpha-helical domain (residues 25 to 172) participates in a two-chained coiled coil, 22 nm long, with two such coiled coils pairing laterally to form the proximal half of the tail. The remainder of the tail (residues 173 to approximately 316) is less uniform in width and is expected to be rich in beta-sheet; the interdimer bonding is evidently sustained through this portion of the molecule. Finally, the globular head consists of the carboxy-terminal domains (which contain the receptor-binding sites) folded into compact globular conformations; in appropriate side views, the head is resolved into two subunits, presumably contributed by the respective dimers. This model for how the four sigma 1 polypeptide chains are threaded in parallel through the fiber is supported by the observed match between an empirical curvature profile, which identifies the locations of relatively flexible sites along the tail, and the flexibility profile predicted on the basis of the model. Appraisal of the interactions that stabilize the coiled coils suggests that (i) the alpha-helices are individually only marginally stable, a property that may be of significance with regard to the retracted conformation in which sigma 1 is accommodated in the intact virion, and (ii) the predominant interactions between the two coiled coils are likely to involve hydrogen bonding between patches of uncharged residues.

Amino Acid Sequence↗
PubMed1990

Discitis after discography. The role of prophylactic antibiotics.

Discitis after discography is due to bacterial penetration into the intervertebral disc by a contaminated needle and has an incidence of 1% to 4%. We have examined the prophylactic role of cephazolin administered at the time of discography. An experimental study in sheep using radiographic contrast containing Staphylococcus epidermidis showed that either adding the antibiotic to the intradiscal suspension or giving it intravenously 30 minutes before intradiscal inoculation of bacteria prevented any radiographic, macroscopic or histological signs of discitis; all the intervertebral disc cultures were negative. In a prospective clinical study of 127 consecutive patients having lumbar discography, the injected contrast contained cephazolin 1 mg per ml. None of the patients developed clinical or radiographic signs of discitis. We recommend the use of a suitable broad spectrum antibiotic in a single prophylactic dose whenever the intervertebral disc is entered.

Animals↗
PubMed1990

Lumbar intervertebral disc prolapse in teenage twins. A case report and review of the literature.

We report the cases of teenage twin girls presenting within months of each other with severe symptoms from lumbosacral disc prolapses, requiring laminectomy in one and chemonucleolysis in the other. CT scans showed similarities in spinal configuration, including the presence of disc bulges at the L4-5 level. This suggests a strong hereditary factor in prolapse of intervertebral discs, but a review of the literature showed little information on that aspect.

Adolescent↗
PubMed1990

A review of fractures of the atlas vertebra.

From 48 consecutive cases of atlas fractures presenting over a 12.5-year period, two groups are apparent that differ in age, presentation, mechanism of injury, and treatment given. Jefferson fractures were, on average, 42 years of age. Displaced Jefferson fractures were treated by traction. At final review, those that had been reduced and those that were initially undisplaced did better than the displaced group. Inadequate reduction was often obtained due to insufficient traction. Patients sustaining a posterior arch fracture were generally more elderly and were, on average, 17 years older than those with a Jefferson fracture. Patients with a posterior arch fracture had marked degenerative changes in the mid- to distal cervical spine and almost invariably had another cervical spine fracture. Treatment was usually directed to the other cervical spine injury. Injury in the elderly usually followed low velocity trauma.

Accidents↗
PubMed1989

The effects of compensation on recovery from low-back injury.

The influence of compensation on recovery from low-back pain was assessed in a retrospective controlled cohort study. One hundred fifty compensable and 150 noncompensable back injury patients were invited for review between 1 and 5 years from presentation. A 91.3% follow-up was achieved, and there was no difference in the median age, follow-up, and initial injury score between the two groups. The incidence of reported pain, disability, psychological disturbance, unemployment, and length of time off work was greater in the compensation group (P less than 0.001). Settlement of the claim did not result in any reduction in morbidity, even up to 5 years later. These results demonstrate that the payment of compensation delays recovery from low-back injury.

Adult↗
PubMed1989

Iatrogenic discitis: the role of intravenous antibiotics in prevention and treatment. An experimental study.

The role of antibiotics in the treatment of iatrogenic discitis remains controversial. This study was carried out to assess the ability of cephazolin (a first-generation cephalosporin) to penetrate the intervertebral disc and to establish the role of intravenous antibiotics in the prevention and treatment of iatrogenic discitis. Six sheep had 1 g of intravenous antibiotic administered between 30 minutes and 120 minutes before being killed. Two adjacent lumbar intervertebral discs were harvested and assayed for antibiotic concentration. Cephazolin could only be detected in the animals killed at 30 minutes. Intravenous cephazolin was administered 30 minutes before bacterial inoculation in 46 discs of nine sheep. In five animals, the bacterial suspension contained radiographic contrast and, in four sheep, reconstituted chymopapain. No evidence of discitis was found at any level at death. Eight sheep were treated with intravenous cephazolin commencing 1, 2, or 3 weeks after bacterial intradiscal inoculation and for periods of up to 21 days. All discs developed discitis, and the lesions appeared to be similar, irrespective of time between inoculation and the commencement, duration, and dosage of antibiotic therapy. Our study supports the use of a suitable broad-spectrum antibiotic during any surgical procedure that invades the intervertebral disc. Antibiotics, however, are unable to arrest the progression of discitis once it is established

Animals↗
PubMed1989

Paraplegia following surgery of the descending thoracic aorta.

Paraplegia remains an uncontrollable complication of aortic reconstructive surgery. Twenty-one consecutive patients undergoing surgery at the Royal Adelaide Hospital for lesions of the descending thoracic aorta were reviewed. Those patients suffering an acute traumatic transection had a much higher rate of postoperative paraplegia (40%) than those undergoing elective reconstruction of chronic aneurysms (10%). The incidence of paraplegia after surgery for an acute transection when bypass was not employed was greater than 50%. In contrast, the outcome was successful in all patients who underwent reconstruction using left heart extracorporeal bypass. Based on these findings, the routine use of bypass during reconstruction of the thoracic aorta is recommended, particularly for acute traumatic transection.

Adult↗
PubMed1989

Reduction and stabilisation of cervical dislocations. An analysis of 167 cases.

We compared retrospectively consecutive series of patients with cervical dislocation treated at two Australian centres. In Perth, 82 patients were treated by closed reduction and postural nursing. In Adelaide, 85 patients had closed reduction and early surgical stabilisation by interbody fusion. There were 46 bilateral dislocations, 101 unilateral dislocations, and 20 anterior subluxations. On admission 30 patients had complete tetraplegia, 17 incomplete tetraplegia, and 120 had minimal or no neurological loss. Our results indicated that closed manipulation under general anaesthesia is a safe and effective means of reduction in the acute stage. There was a high mortality rate for acute surgery in patients with complete tetraplegia. Early surgical stabilisation by dowel fusion reduced bed and hospital stay in patients with no neurological loss, but seemed to impair neurological recovery in patients with a neurological deficit on admission. Conservative management after reduction of bilateral dislocation or anterior subluxation led to a higher incidence of instability in patients with minimal or no neurological loss; in such cases surgery to stabilise the injured segment is indicated.

Adolescent↗
PubMed1989

The value of computerized tomography in determining lumbar facet joint orientation.

The reliability of assessing facet joint obliquity from standard CT scans in the lumbar spine was studied. There was no significant difference in repeated measurements by one single examiner, nor in measurements made by different examiners. Measurement of facet joint obliquity from CT scans made on different occasions was not significantly different either. This reproducibility occurred despite the fact that adjacent CT scans from one joint extremity to the other showed variation in obliquity of about 11%.

Analysis of Variance↗
PubMed1988

Management of a patient with traumatic tetraplegia from Central Australia: case report.

During the 6-year period up to 1 January 1988, 10 patients were admitted to our unit from Central Australia with spinal cord injuries resulting from motor vehicle accidents. Of these half had received their injury whilst resting unrestrained in the rear of a moving vehicle. Three of these were recumbent. The case is presented of a 26-year-old male who was injured whilst resting in the rear of a moving vehicle that left the roadway and rolled in remote central Australia. The injuries sustained were a closed head injury, fractures of the left lateral masses of C5, C6 and C7, a burst fracture of C7 with an asymmetrical complete tetraplegia: C5 on the left, C6 on the right. Initial orthopaedic management was skeletal traction. An inpatient rehabilitation programme has been completed.

Accidents, Traffic↗
PubMed1987

Molecular packing in type I collagen fibrils.

Previous studies of the X-ray diffraction pattern of the crystalline regions of type I collagen fibrils yielded information on the unit cell parameters and also the orientation of the pseudo-hexagonally packed molecular segments in the overlap region. The absence of Bragg reflections at high angles attributable to the molecular segments in the gap region led to the suggestion that these segments were more mobile than those in the overlap region. We report a study of the low-angle Bragg reflections in a search for information about the nature of the orientation and packing of the molecular segments in the gap region. We conclude that the (m = 0, n = 0) helix layer plane of the molecular segments in the overlap region makes little or no contribution to the Bragg reflections at low angles, and identify three possible origins for the observed low-angle reflections in the electron density contrast associated with: (1) the "hole" created by the missing molecular segment in the gap region; (2) the telopeptides; or (3) the axial regularities in amino acid residues of a particular type, with periodicities of D/5 or D/6. Sufficient information is available to investigate the first two of these possibilities, and the results obtained suggest specific arrangements for the molecular segments in the overlap and gap regions, and specific connectivities between the molecular segments in successive overlap regions. In addition, we have examined the amino acid sequence and identified features related to the mobility of the molecular segments in the gap region and to the regions where it is thought that molecules are kinked.

Amino Acid Sequence↗