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Biomedical subjects

A M Jackson

Publications and source records attributed to A M Jackson.

At least 73 records · Page 4Linked to original sources
PubMed1990

Adhesion of carboxylate cements to hydroxyapatite. III. Adsorption of poly(alkenoic acids).

Investigations into the effects of relative molecular mass (RMM) and structure of poly(alkenoic acid)s on their adsorption on to hydroxyapatite (HAP) were carried out with a view to establishing factors that influence the adhesion of glass-poly(alkenoic acid) cements to tooth material. The effects of pH and fluoride addition were also studied. It was found that high adsorption levels were achieved under conditions of high chain entanglement, such as in a concentrated solution of a polyacid of high RMM. Theories of adsorption of carboxylic acids on to HAP are reviewed in the light of these studies and previous work at our laboratory.

Adsorption↗
PubMed1990

Adhesion of carboxylate cements to hydroxyapatite. II. Adsorption of aromatic carboxylates.

An investigation was made into the effect of structure and functionality of aromatic carboxylates on their adsorption on to hydroxyapatite (HAP) with a view to identifying factors affecting the adhesion of polyacrylate cements to tooth materials. In general, the amount of carboxylate adsorbed was found to increase with the number of groups contained in the molecule. The arrangement of these groups around the benzene ring also affected adsorption. These results suggested that adsorption was the result of a cooperative effect between carboxylate groups. An adsorption isotherm for mellitate on to HAP was constructed.

Adhesiveness↗
PubMed1990

Congenital snapping knee. Habitual anterior subluxation of the tibia in extension.

We describe a rare form of congenital snapping knee. In six knees in four children, the tibia subluxed anteriorly on the femur when the knee was extended and reduced spontaneously on flexion. The abnormal movements were seen and felt as sudden snaps or clunks at about 30 degrees of flexion. All six knees showed similar dysplastic features, although the patients had different clinical syndromes. The mechanism of the subluxation and its management are discussed.

Child↗
PubMed1989

Cytokine production in culture by cells isolated from the synovial membrane.

Cytokine expression was investigated in synovial cell cultures isolated from diseased joints of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Tumour necrosis factor alpha (TNF alpha) was produced spontaneously at high levels by both RA and OA synovial cells. There was no correlation between cell composition and level of TNF alpha produced. In contrast, lymphotoxin (LT) and Interferon gamma (IFN gamma) (greater than 50 pg/ml) were not found. This was further investigated in the RA cultures at both the mRNA and protein level. The results indicated that high levels of mRNA were produced spontaneously by these cells, but the relevant protein was undetectable. The presence of inhibitors and/or shed receptor is unlikely to account for undetectable LT as most of the recombinant LT added to the cultures could be recovered. In addition, in some cases this resulted in an increase in IL-1 production indicating that LT is biologically active in this system. It is not clear at this stage why the protein for these mediators (produced by activated T cells) are not found in the rheumatoid cultures, although it may be due to a post-transcriptional mechanism. This possibility is currently being investigated in addition to the development of more sensitive assays for these cytokines.

Arthritis, Rheumatoid↗
PubMed1988

T cells expressing gamma delta chain receptors in rheumatoid arthritis.

Whereas the majority of T cells use alpha and beta chains to form their T-cell receptor, a small minority of T cells, which do not express the CD4 or CD8 surface markers, use other chains termed gamma and delta to form their receptor. Flow cytometry was performed on cells isolated from the blood and synovial joints of patients with rheumatoid arthritis. Monoclonals which recognise the gamma and delta chains were used to compare the proportion of TCR gamma delta cells in these sites. Approximately half the patients had more TCR gamma delta in the joints than in their blood and one newly diagnosed patient had high numbers of TCR gamma delta cells in both blood and joints. In this preliminary study it is not possible to evaluate the role of these cells in the disease process, but it is of interest that in some RA patients there is an overabundance of both T cells that arise early in ontogeny (TCR gamma delta cells) and B cells that arise early in ontogeny, the CD5 B cell.

Antibodies, Monoclonal↗
PubMed1986

Neuropathic osteonecrosis of the lateral femoral condyle in childhood. A report on four cases.

Four children are described, each with spontaneous osteonecrosis affecting nearly one-third of the lateral femoral condyle. All the children had a motor and a sensory deficit in the affected limb: two had been previously treated for neuroblastoma of the spine, one for an infected lumbar dermoid cyst and one had spina bifida. We consider that these disorders, singly or in combination, may lead to repeated excessive loading of the lateral femoral condyle, which cannot be appreciated in a knee that is not protected by normal sensation.

Adolescent↗
PubMed1985

The Mezzich MMPI regression formula revisited.

In a sample of depressed psychiatric inpatients, the Mezzich regression formula, based on five MMPI scales, correlated moderately with clinicians' judgments and yielded few false negative diagnoses in identifying patients with unipolar Major Depressive Disorder, but was less effective in eliminating false positives.

Adult↗
PubMed1985

Injection-induced contractures of the quadriceps in childhood. A comparison of proximal release and distal quadricepsplasty.

Thirty-two contractures of the quadriceps induced by injection in 17 children have been reviewed. The average age at presentation was 3 years 4 months. All the children had suffered a severe illness within the first few weeks of life and all had received intramuscular injections into the thigh. Three methods of treatment were used: conservative, distal quadricepsplasty, and proximal release. At follow-up none of the patients treated by proximal release had an extension lag, which was present in 70% of those treated by distal quadricepsplasty. Apart from one case with slight improvement in the range of knee flexion, conservative treatment, at best, could only prevent further loss. The clinical presentation and management is described, and the advantages of proximal release are discussed.

Child↗
PubMed1985

Congenital absence of the anterior cruciate ligament. A common component of knee dysplasia.

The clinical and radiological features of 12 knees (10 patients) with congenital absence of the anterior cruciate ligament are presented. The high frequency of this condition in association with other more easily recognised congenital abnormalities of the knee is discussed. It is concluded that congenital absence of the anterior cruciate ligament is more common than generally suspected and is associated with other developmental abnormalities of both bone and soft tissue in the lower limb, particularly around the knee joint.

Adolescent↗
PubMed1984

The long-term results of conservative management of severely displaced fractures of the calcaneus.

A subjective, objective and radiographic study of 21 patients with comminuted calcaneal fractures showing severe involvement of the subtalar joint is reported. The average follow-up was 14.6 years (range 8 to 29 years). Only patients with unilateral closed fractures and no associated injuries to either lower limb were admitted to the study. All were treated by early active mobilisation of the ankle, and the subtalar and the midtarsal joints. Seventy-six per cent of the patients achieved a good result with minor symptoms which did not interfere with their occupation or leisure requirements. Although two-thirds of the patients reached a point of maximal recovery at two to three years, 24% continued to improve for six years. None of the patients experienced any deterioration after this time. Neither the degree of clinical stiffness nor the degeneration of the subtalar joint, assessed radiographically, correlated with the severity of symptoms or functional disability. The role of the soft tissues in the aetiology of residual symptoms is discussed.

Adult↗
PubMed1984

Thrombotic microangiopathy and renal failure associated with antineoplastic chemotherapy.

Five patients with carcinoma developed thrombotic microangiopathy (characterized by renal insufficiency, microangiopathic hemolytic anemia, and usually thrombocytopenia) after treatment with cisplatin, bleomycin, and a vinca alkaloid. One patient had thrombotic thrombocytopenic purpura, three the hemolytic-uremic syndrome, and one an apparent forme fruste of one of these disorders. Histologic examination of the renal tissue showed evidence of intravascular coagulation, primarily affecting the small arteries, arterioles, and glomeruli. Because each patient was tumor-free or had only a small tumor at the onset of this syndrome, the thrombotic microangiopathy may have been induced by chemotherapy. Diagnosis of this potentially fatal complication may be delayed or missed if renal tissue or the peripheral blood smear is not examined, because renal failure may be ascribed to cisplatin nephrotoxicity and the anemia and thrombocytopenia to drug-induced bone marrow suppression.

Adult↗