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Biomedical subjects

B Vernon-Roberts

Publications and source records attributed to B Vernon-Roberts.

At least 55 records · Page 3Linked to original sources
PubMed1990

Age-related changes in femoral trabecular bone in arthrosis.

Age-related changes in the cancellous bone in selected regions of the proximal femur and iliac crest were assessed. An arthrosis group and a control cadaver group, partitioned into subjects younger and older than aged 50 years, were compared. The control group comprised 69 heads of femur and iliac crest samples. The arthrosis group comprised 28 consecutive heads of femur affected by primary arthrosis and an iliac crest biopsy taken during hip arthroplasty. Cancellous bone was sampled from four selected regions in the proximal femur. Histomorphometric estimates of percentage bone volume were determined using image analysis. In the young controls the bone volume was higher than that in the old controls for all the regions. In the arthrosis group the bone volume was higher than that of the old controls except for the subchondral principal tensile and medial to the greater trochanter regions. The old controls had regression of bone volume on age for the subchondral and medial principal compressive regions and the iliac crest. The arthrosis group had a minimal dependence of bone volume on age. Our study showed that primary arthrosis modulates the age dependence of bone volume in the proximal femur.

Adult↗
PubMed1990

Resurfacing hip arthroplasty. Classification of loosening and the role of prosthesis wear particles.

Operative grading of loosening and histologic examination of the periprosthetic tissues and the femoral and acetabular bone-cement interfaces were undertaken in 72 revised resurfacing hip arthroplasties. By correlating the degree of macroscopic and microscopic loosening at the bone-cement interface, a classification of the stages of loosening at the bone-cement interface was devised. Examination of the femoral bone-cement interface of solidly fixed prosthesis components has demonstrated the presence of polyethylene wear particles and a macrophage response at the interface prior to loosening. This suggests that wear particles may migrate along bone-cement interfaces that are both macroscopically and microscopically solid, and emphasizes the important role of wear particles in prosthesis loosening.

Adult↗
PubMed1989

Effect of mitogen and lymphokine stimulation on proteoglycan synthesis by lymphocytes.

The ability of mouse thymocytes and peripheral blood lymphocytes from rats to synthesize and secrete proteoglycans in the presence of a variety of mitogens and lymphokines was studied in vitro, and it was confirmed that such lymphocytes synthesize and secrete significant quantities of proteoglycans. Mitogenic stimulation of the cells with phytohaemagglutanin (PHA) induced a fourfold increase in proteoglycan synthesis; stimulation with interleukin-1 stimulated proteoglycan synthesis up to fivefold. Proteoglycan synthesis could also be stimulated by culturing the cells in the presence of interleukin-2. To determine if this response was related to cell proliferation, the cells were cultured in the presence of PHA and either cyclosporine or prostaglandin E2, two agents that inhibit lymphocyte proliferation. Under these conditions, proteoglycan synthesis remained elevated, indicating that this effect may be independent of cell proliferation. Chemical analysis of the proteoglycans indicated them to be composed of chondroitin sulfate and heparan sulfate. Their molecular size was small compared with cartilage proteoglycans but similar to the small dermatan sulfate proteoglycans synthesized by fibroblasts. On the basis of molecular size, three proteoglycan population were identified, and their relative proportions were altered by mitogenic stimulation of the cells. Taken together, these findings imply that proteoglycan synthesis is intimately associated with lymphocyte activation and may be related to cellular function in immune responses.

Animals↗
PubMed1989

Mathematical modelling of trabecular bone structure: the evaluation of analytical and quantified surface to volume relationships in the femoral head and iliac crest.

The three-dimensional architecture of trabecular bone has structural trends related to physical function as described by Wolff's law. Mathematical modelling provides a means of analysing these structures through the use of simplified representations. A single measure of mineralized bone volume per unit volume of structure (Vv) and the surface area of mineralized bone per unit volume of structure (Sv) does not identify a particular architecture in any detail; the way in which Sv changes in relation to Vv does provide this information as the structure remodels. A series of structures using the elements of plates and rods were created. The rates of change of Sv with respect to Vv for trabecular structures give insight into differences in such models. Structures in the femoral head and iliac crest were analysed by power curve regression. In the principal compressive region, just above the medial cortex, advanced osteoarthritis was associated with a preferential loss of rods from the normal trabecular structure, resulting in a more plate-like architecture. The iliac crest remodelling that takes place in the osteoporotic appears to be the result of a generalised bone loss with some of the thinner elements of the structure being removed completely, resulting in an increase in unit cell dimension. The consequence of changing unit cell size has a major impact on surface availability for osteoblastic and osteoclastic activity. The simple plate model as a basis for the stereological analysis of trabecular structures is therefore limited because of the mixed plate and rod nature of trabecular architecture.

Anthropometry↗
PubMed1989

Effect of cyclosporine-A on connective tissue deposition in experimental inflammatory lesions.

The effect of cyclosporine-A, a potent immunosuppressant, on the development of experimental inflammatory lesions in rats was studied both histologically and biochemically. Continuous treatment with cyclosporine was begun after the implantation of sponges impregnated with heat-killed Mycobacterium tuberculosis and continued for up to 63 days. Cyclosporine-A significantly reduced the numbers of neutrophil polymorphonuclear leukocytes and lymphocytes present during both the acute and chronic phases. In addition, greater amounts of mature fibrous tissue were present in the sponges removed from animals which had been treated with cyclosporine-A. Biochemical analyses of the collagen and glycosaminoglycan content of the sponges at varying times confirmed that cyclosporine-A can influence the deposition of connective tissue macromolecules. These data provide additional evidence that cyclosporine-A affects not only the inflammatory response but also influences subsequent connective tissue metabolism.

Animals↗
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

Comparison of two bone trephine instruments used for quantitative histomorphometry.

Transilial bone samples were obtained at necropsy using trephine instruments with internal diameters of 2 mm and 7 mm. Undecalcified histological sections were prepared and two structural histomorphometric variables (percentage of trabecular bone volume and surface density of bone) were estimated by a Quantimet 720 image analyser. The differences between the variables measured from the two adjacent cores were due to differences in biopsy site rather than the size of the sample. The smaller diameter needle is therefore recommended for use as the biopsy procedure is simpler and tissue sections can be prepared sooner than is the case with the larger needle.

Adult↗
PubMed1989

Comparative study of iliac crest and proximal femur histomorphometry in normal patients.

The relation between the bone histomorphometric profile of the iliac crest and regions of the proximal femur was investigated. In the proximal femur four blocks were selected, representing the subchondral principal compressive (SPC) and tensile (SPT) regions, the zone near the medial cortex in the principal compressive region (MPC), and the zone medial to the greater trochanter (MGT). Undecalcified tissue sections stained by the von Kossa silver method and counterstained with haematoxylin and eosin were used for quantitation. The SPT region was most representative of the iliac bone profile, in particular the structural parameters of mineralised bone, trabecular thickness, and trabecular spacing and resorption surface. Most parameters in the regions studied showed inconsistent and variable results when compared with those of the iliac crest. There was only a weak association, therefore, between the histomorphometric parameters of the iliac crest and the proximal femur despite the appeal of the use of the iliac biopsy specimen as a simple clinical test.

Adolescent↗
PubMed1989

Variation in histomorphometric estimates across different sites of the iliac crest.

Bone specimens were obtained from four different sites in the ilium of necropsy cases using a Jamshidi 8G trephine needle. Undecalcified histological sections were prepared and two structural histomorphometric parameters were estimated. Estimates of the percentage of trabecular bone volume (%TBV) deviated systematically, with variation of the biopsy site around the usual location, increasing in magnitude from the anterior to the posterior ilium. Such differences highlight the importance of understanding the degree of variation which exists in histomorphometric data. The histomorphometry of a vertical biopsy specimen of the iliac crest did not differ significantly from that of a transilial biopsy specimen of similar diameter taken from an adjacent site. When taken at the standard site, and when providing a long core of cancellous bone, with minimal discomfort to the patient, the vertical biopsy specimen compares well with the transiliac biopsy specimen for use for investigating metabolic bone disorders.

Adult↗
PubMed1989

Trabecular microfractures. Nature and distribution in the proximal femur.

The nature and distribution of healing trabecular microfractures (TMF) of femoral heads were studied in 50 autopsy specimens, 30 patients with osteoarthritis (OA) of the hip and 45 patients with subcapital fractures of the femoral neck (SFFN). Macerated coronal slices were examined with a dissecting microscope, and the TMFs were identified where there was callus formation, either nodular or smooth. The number of TMFs did not differ significantly in the SFFN and age-matched control groups. The number of TMFs in the OA group was lower than in SFFN and age-matched control groups. The numbers of nodular TMFs in the control and SFFN groups did not differ significantly but were fewer in the OA group. Smooth TMFs were present in similar numbers in OA, control, and SFFN groups. The ratio of the nodular to smooth TMFs regressed with age. The greater proportion of nodular TMFs in older patients was indicative of an early stage of woven bone callus formation. In all three groups (excluding controls younger than 50 years of age), TMFs tended to appear some distance from the midpoint of the trabeculae. The number of TMFs in trabeculae parallel and perpendicular to the direction of principal stress was similar in all three groups.

Adult↗
PubMed1988

Effect of gold salt treatment on the receptor binding activity of monocytes and macrophages isolated from rats with adjuvant arthritis.

We investigated the effect of chrysotherapy on the Fc and complement receptor binding activity of peripheral blood (PB) monocytes and peritoneal (PE) macrophages isolated from normal rats and rats with adjuvant induced arthritis. The adjuvant induced severe disease in Dark Agouti (DA) rats and less marked disease in J. C. Lewis (JC) rats. Gold treatment reduced the disease in DA rats but exacerbated the disease in JC rats. PB monocytes generally exhibited increased receptor activity after adjuvant injection. Gold treatment resulted in a simultaneous reduction of the PB monocyte receptor activity and increased the PE macrophage receptor activity. This was considered to be due to a direct effect of gold, since the Fc receptor activity of PE macrophages increased after in vitro gold treatment.

Animals↗
PubMed1988

Synovial macrophage response to aluminium oxide ceramic and cobalt-chrome alloy wear particles in rats.

The tissue response to intra-articular injection into rat knees of similar concentrations of sterile cobalt-chrome (Co-Cr) alloy and aluminium oxide (AL2O3) ceramic prosthesis wear particles was assessed at 1, 4 and 13 wk. A semiquantitative method of histological assessment showed a correlation between the numbers of particles and macrophage response in the tissues, and a difference in the response to different concentrations of Co-Cr particles. At 1 wk, the macrophage response to Co-Cr particles was significantly greater (p less than or equal to 0.01) than that to AL2O3 particles but no difference was detected at 4 and 13 wk. The difference may be due to necrosis of macrophages induced by Co-Cr particles.

Aluminum↗
PubMed1988

Long-term effects of intraarticular cobalt-chrome alloy wear particles in rats.

The long-term effects of cobalt-chrome alloy prosthesis wear particles were studied using intraarticular injection of particles into rat knees and killing the rats at regular periods from 1 week to 2 years following injection. The initial response was synovial ulceration, macrophage infiltration, and necrosis. A transient lymphocyte response was present at 1 week. Fibrosis of the subsynovium occurred subsequently at the sites of necrosis. A semiquantitative assessment of the number of particles and macrophages in the synovium demonstrated that the distribution of particles did not alter during the period from 1 week to 1 year. The macrophage response decreased between 1 and 2 weeks and then remained constant for 1 year. No tumors developed. This study emphasizes that cobalt-chrome wear particles and the associated macrophage response persist in the tissues for up to 2 years. The findings are relevant to the effects of wear of all designs of cobalt-chrome alloy prostheses.

Animals↗
PubMed1988

Osteofibrous dysplasia of the tibia and fibula.

Osteofibrous dysplasia (ossifying fibroma of long bone) is an uncommon disorder of bone affecting the tibia and, rarely, the fibula of children and adolescents. It has been delineated from monostotic fibrous dysplasia, from which it can be distinguished by its radiological and histological characteristics and by its clinical course. We report 11 patients with osteofibrous dysplasia whose ages ranged from 10 months to 22 years. Four presented with a pathological fracture and in 2 a pseudarthrosis developed. A circumscribed area of intracortical lucency and expansion in the diaphysis is the characteristic radiological finding. Histologically there is a similarity to fibrous dysplasia but the trabeculae are lamellar or have a lamellar surface and most show osteoblastic rimming. Treatment may be difficult but more recent experience strongly favours a conservative approach wherever possible.

Adolescent↗
PubMed1988

Parosteal (periosteal) lipoma.

Parosteal (periosteal) lipoma is a rare tumour, comprising 0.3% of all lipomas. A parosteal lipoma of the mid humerus which presented in a female of 22 years was associated with changes in the adjacent bone. A review of the literature revealed only one previously reported similar case. The etiology, presenting symptoms, complications, differential diagnosis, treatment and prognosis of parosteal lipoma are discussed.

Adult↗
PubMed1988

Do gold drugs inhibit interleukin-1? Evidence from an in vitro lymphocyte activating factor assay.

The ability of some antiarthritic gold (I) compounds to inhibit the in vitro lympho-proliferative activity of human interleukin-1 (IL-1) in the lymphocyte activating factor (LAF) assay was investigated. Marked inhibition was seen at concentrations of auranofin (AF) and gold sodium thiomalate (GSTM) that correspond to gold levels found in the serum of patients receiving these drugs. This inhibition was not due to direct inactivation of the IL-1 molecule. Omitting 2-mercaptoethanol from the LAF assay potentiated the effect of GSTM. The antiproliferative effect of AF occurs almost immediately and probably reflects its direct cytotoxicity to stimulated lymphocytes.

Animals↗