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Biomedical subjects

A J Malcolm

Publications and source records attributed to A J Malcolm.

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

Increase in severity of graft versus host disease by cytomegalovirus.

An allogeneic transplant recipient developed severe graft versus host disease (GvHD) 48 days after transplantation that was concomitant with a cytomegalovirus (CMV) viraemia, from which she subsequently died. CMV infection was detected in blood by the polymerase chain reaction and later in tissue by immunohistochemical techniques. CMV should be considered in patients in whom GvHD does not respond to appropriate treatment, and this case suggests that herpes viruses may increase the severity of GvHD by synergistically enhancing the graft versus host reaction.

Adult↗
PubMed1992

Alveolar rhabdomyosarcoma infiltrating bone marrow at presentation: the value to diagnosis of bone marrow trephine biopsy specimens.

AIMS: To describe the histological appearances of bone marrow infiltrated with rhabdomyosarcoma at presentation and to determine their value in establishing the diagnosis. METHODS: Patients presenting over seven years in the northern health region of England with rhabdomyosarcoma were studied. Bone marrow aspirates and trephine biopsy specimens taken at presentation were examined. RESULTS: Seven of 32 patients with rhabdomyosarcoma had bone marrow infiltration, resulting in marrow failure in all cases, at diagnosis. The diagnosis was established in these seven by the typical cytological appearances and immunophenotype of the infiltrating cells (all seven patients) and cytogenetic abnormalities (three patients). Histological examination of the bone marrow showed a pseudoalveolar pattern with fibrous septal bands, enlarged vascular channels, and lack of cohesion of the tumour cells within the subdivided aggregates in all seven. In four cases multinucleate giant cells, often with peripherally sited nuclei, were found. CONCLUSIONS: These histological features of infiltrated marrow are so characteristic that the diagnosis of alveolar rhabdomyosarcoma can be made, or at least suspected, in many cases even without recourse to technically difficult and expensive further investigations. Bone marrow biopsy should be a routine part of the investigation of patients with bone marrow failure and will be of particular value in the diagnosis of those with disseminated alveolar rhabdomyosarcoma.

Adolescent↗
PubMed1992

Human herpes virus 6 and endogenous biotin in salivary glands.

AIMS: To detect the presence of human herpes virus 6 (HHV6) and endogenous biotin in paraffin wax embedded and frozen salivary glands. METHODS: Two stage indirect and streptavidin-biotin immunoperoxidase techniques were used to visualise the antigens. RESULTS: HHV6 could not be shown in any of the tissues. However, considerable endogenous biotin antigenicity was detected in the glandular elements of the paraffin wax embedded material. CONCLUSIONS: Results obtained with avidin-biotin detection systems should be interpreted with caution, especially when glandular epithelium is being stained. This may apply to both immunoperoxidase and in situ hybridisation techniques. The use of an anti-biotin antibody as a standard control should be considered.

Biotin↗
PubMed1992

Polyethylene wear in uncemented knee replacements.

Isolated wear of the polyethylene tibial component led to failure in five of a series of 108 uncemented porous-coated knee replacements. The clinical features included pain, effusion and instability with progressive varus deformity. In all cases there was extensive wear on the medial side of the polyethylene surface of the prosthesis. The mechanism of such wear is complex, being due in part to the unconstrained nature of the joint and the incongruity of its surfaces. Other design characteristics may have contributed.

Adult↗
PubMed1992

The mechanism of loosening of cemented acetabular components in total hip arthroplasty. Analysis of specimens retrieved at autopsy.

Late aseptic loosening of cemented acetabular components is governed by the progressive, three-dimensional resorption of the bone immediately adjacent to the cement mantle. This process begins circumferentially at the intraarticular margin and progresses toward the dome of the implant. Evidence of bone resorption at the cement-bone interface was present even in the most well-fixed implants before the appearance of lucent lines on standard roentgenographic views. The mechanical stability of the implant was determined by the three-dimensional extent of bone resorption and membrane formation at the cement-bone interface. The leading edge of the membrane is a transition zone from regions of membrane interposition between the cement and the bone to regions of intimate cement-bone contact. Histologic analysis revealed that progressive bone resorption is fueled by small particles of high density polyethylene (HDP) migrating along the cement-bone interface and bone resorption occurs as a result of the macrophage inflammatory response to the particulate HDP. Evidence in support of a mechanical basis for failure of fixation was lacking. The mechanism of late aseptic loosening of a cemented acetabular component is therefore biologic in nature, not mechanical. This is exactly opposite to the mechanism of loosening on the femoral side of a cemented total hip replacement, which is mechanical in nature.

Acetabulum↗
PubMed1991

Cytogenetic analysis of a congenital fibrosarcoma.

Congenital (infantile) fibrosarcoma is a rare soft tissue sarcoma occurring in children aged less than 5 years. We performed cytogenetic analysis on such a tumor, which had an abnormal karyotype: 48,XY, +11, +20. Three other reports of karyotypes in congenital fibrosarcoma describe similar cytogenetic changes, and a specific pattern of trisomies that may prove diagnostic for this tumor is beginning to emerge.

Fibrosarcoma↗
PubMed1991

Primary Sjögren's syndrome in north east England--a longitudinal study.

We have documented the initial clinical features of 100 patients with primary Sjögren's syndrome (SS) together with the results of their baseline investigations. The evolution of the disease in these patients has been followed for a median of 34 months (range 3-84 months). The majority of patients were females aged 40-60 years, and common clinical features included eye symptoms (100%), xerostomia (100%), polyarthralgia (94%), Raynaud's phenomenon (81%) and salivary gland swelling (47%). Thyroid disease was relatively common (14%) while other endocrine disease was rare. Four patients died during follow-up, and three cases of lymphoma were detected. Other serious complications included pericarditis (10%), pleuroparenchymal lung disease (9%), renal tubular acidosis (3%) and cerebrovascular accidents (2%). The presence of anti-Ro antibodies identifies patients with more severe systemic disease. Spontaneous improvement occurred in 12 patients, while steroids were required for specific complications in 18. Overall, although lymphoma was found to excess in our group, the high mortality reported with primary SS elsewhere was not seen.

Adolescent↗
PubMed1991

Immunopathology of early graft-versus-host disease--a prospective study of skin, rectum, and peripheral blood in allogeneic and autologous bone marrow transplant recipients.

The immunopathological appearances of skin and rectum in 64 autologous and allogeneic recipients were determined before and after bone marrow transplantation. Patients who developed acute graft-versus-host disease were biopsied as soon as a clinical diagnosis was made. At the same time peripheral blood samples were collected for comparative analysis. Immunohistological and morphometric techniques were employed using a panel of monoclonal antibodies to T lymphocytes and subsets, B lymphocytes, natural killer cells, macrophages, and Langerhans cells. A reduction in the CD4/CD8 ratio after BMT was seen in skin and rectal biopsies from both autologous and allogeneic recipients with or without GVHD. The same pattern was observed in blood samples taken at the same time. Langerhans cells were reduced in the skin in all patients after BMT, probably by the conditioning regimen. Only a few cells expressing activation or natural killer cell markers were present and there were no changes observed in the macrophage population. This study has provided no evidence to implicate either CD4- or CD8-positive T lymphocytes as the initiators of the cellular damage in acute GVHD. The distribution of lymphocyte subsets in the blood was similar to that in the tissues, suggesting that the tissue changes reflect the pattern of lymphocyte repopulation after BMT and may have little bearing on the pathogenesis of GVHD.

Adolescent↗
PubMed1991

Routine histological compared with immunohistological examination of bone marrow trephine biopsy specimens in disseminated neuroblastoma.

The ability to detect infiltration in bone marrow biopsy specimens from patients with disseminated neuroblastoma was assessed by immunohistological and routine histological methods. Frozen cores from 33 staging procedures were tested with UJ13A and UJ127.11. Immunopositive tumour cells were found in 10 of 17 staging procedures in which tumour was detectable by routine histological methods. Positive cells or stromal material were also found in eight of 12 staging procedures in which distorted architecture and fibrosis, but no obvious tumour, had been noted. Paraffin wax embedded cores from 29 of the same staging procedures were tested with antibodies against neurone specific enolase and neurofilament. Only a single core reacted with anti-neurofilament antibody. Neurone specific enolase positive cells or stromal material were found in nine of 15 staging procedures in which obvious tumour was detectable. Although these immunohistochemical techniques proved inferior to routine histology in their ability to detect obvious tumour, the demonstration of immunopositive stromal tissue which was not frankly malignant supports the view that distorted, fibrotic marrow may reflect persistence of neuroectodermal tissue and justifies its distinction from normal marrow when reporting the response to treatment.

Adolescent↗
PubMed1991

Effect of a purified somatostatin monoclonal antibody and its Fab fragments on gastrin release.

The effect of a purified somatostatin monoclonal antibody, SOMA 10, and its Fab fragments on gastrin release have been examined in the isolated perfused rat stomach. SOMA 10 was purified from ascites fluid by ammonium sulfate precipitation followed by hydroxylapatite (HAP) chromatography. This gave a preparation of greater than 90% purity, as assessed by fast affinity and size exclusion high-performance liquid chromatography (HPLC). HAP-purified SOMA 10 had a binding capacity of 760 mmol somatostatin/mol antibody, a dissociation constant of 2.2 nM, and recognized amino acid residues 5-12 of the somatostatin molecule. Fab fragments of SOMA 10 were prepared and purified by protein A affinity chromatography, and the purity assessed by HPLC and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Single passage perfusion of SOMA 10 (100 micrograms/ml) into the gastric vasculature caused a paradoxical decrease in basal gastrin release. However, recirculation of the antibody (20 micrograms/ml) caused an increase in cumulated gastrin release. Perfusion of Fab fragments of SOMA 10 (66 micrograms/ml) also increased gastrin secretion. These results support the suggestion that somatostatin exerts a tonic restraint on gastrin release and that penetration of the antibody to the site of somatostatin release is necessary for it to have an effect.

Animals↗
PubMed1990

Afferent and efferent synaptic connections of somatostatin-immunoreactive neurons in the rat fascia dentata.

The aim of this study was to determine whether somatostatin (SS)-immunoreactive neurons of the rat fascia dentata are involved in specific excitatory circuitries that may result in their selective damage in models of epilepsy. Synaptic connections of SS-immunoreactive neurons were determined at the electron microscopic level by using normal and colchicine pretreated rats. Vibratome sections prepared from both fascia dentata of control animals and from rats that had received an ipsilateral lesion of the entorhinal cortex 30-36 hours before sacrifice were immunostained for SS by using a monoclonal antibody (SS8). Correlated light and electron microscopic analysis demonstrated that many SS-immunoreactive neurons in the hilus send dendritic processes into the outer molecular layer of the fascia dentata, and dendrites of the same neurons occupy broad areas in the dentate hilar area. The majority of SS-immunoreactive axon terminals form symmetric synapses with the granule cell dendrites in the outer molecular layer and also innervate deep hilar neurons. Via their dendrites in the outer molecular layer, the SS-immunoreactive neurons receive synaptic inputs from perforant pathway axons which were identified by their anterograde degeneration following entorhinal lesions. The axons from the entorhinal cortex are the first segment of the main hippocampal excitatory loop. The hilar dendrites of the same SS-immunoreactive cells establish synapses with the mossy axon collaterals which represent the second member in this excitatory neuronal chain. These observations suggest that SS-immunoreactive neurons in the dentate hilar area may be driven directly by their perforant path synapses and via the granule cells which are known to receive a dense innervation from the entorhinal cortex. These observations demonstrate that SS-immunoreactive neurons in the hilar region are integrated in the main excitatory impulse flow of the hippocampal formation.

Animals↗
PubMed1990

Demonstration of Epstein-Barr viral DNA in formalin-fixed, paraffin-embedded samples of Hodgkin's disease.

The presence of Epstein-Barr virus (EBV) DNA in formalin-fixed, paraffin-embedded samples of Hodgkin's disease (HD) was investigated by Southern blot hybridization using a specific EBV Bam H1W fragment probe. DNA from 16 samples of HD in children and young adults was compared with that from ten samples in adults older than 45 years. A further eight cases of DNA extracted from fresh samples of HD were also studied, in order to compare the results obtained with fresh and fixed tissue samples. Hybridization was demonstrated in 15 of the 34 cases of HD studied in contrast to 3 or the 34 control specimens of non-Hodgkin's lymphoma, non-neoplastic lymph nodes, and carcinomas. No differences between the two age groups compared were found. The results of this study suggest that there is a definite association between EBV and HD, although the exact nature of this association remains to be established. It has also been shown that DNA of sufficient quality for the detection of EBV DNA can be extracted from formalin-fixed, paraffin-embedded material, and that comparable results can be obtained using DNA extracted from fresh and fixed tissue.

Adolescent↗