Biomedical subjects
Publications and source records attributed to R A Sharp.
Extramedullary haemopoiesis resulting in spinal cord compression is rare. This report of extramedullary myeloid metaplasia in a patient with myelofibrosis serves to illustrate the value of magnetic resonance imaging (MRI) in the diagnosis and management of good neurological recovery.
A 64-year-old lady with a personal and family history of autoimmune disease developed chronic myelomonocytic leukaemia and multiple myeloma simultaneously. Her sister died of acute myelomonocytic leukaemia, but showed no evidence of autoimmune disease. It is possible that chronic immunological stimulation, perhaps by an autoantigen, may predispose toward malignant transformation in both plasma cell and monocyte series. However, the present observations raise the alternative possibility of a primary disorder of monocytes that predisposes toward both autoimmune disease and a clonal disorder of plasma cells.
Two cases of sideroblastic anaemia associated with antituberculous therapy are reported. The first, in whom there was a constitutional chromosomal abnormality and peripheral neuropathy, recovered on withdrawal of isoniazid and pyridoxine treatment. The other, who had been given a four-drug combination including isoniazid and pyrazinamide and recovered on the withdrawal of isoniazid alone, highlights the increasing likelihood of this complication in patients treated for tuberculosis, since this drug combination has regained popularity in recent years.
Bone marrow sections from posterior iliac crest aspiration and/or trephine specimens have been examined in 39 patients with true polycythaemia, along with a variety of other clinical and laboratory data. The emphasis has been on objective assessment of cellularity and megakaryocyte concentration in a prospective four year study. In patients with untreated primary polycythaemia mean cellularity was 87.0% and 86.4% for aspirate and trephine specimens compared with 55.5% and 48.7% for secondary cases and 48.3% and 45.5% for controls. Eighty per cent of primary polycythemia patients had moderate to marked megakaryocytic hyperplasia. We conclude that, in the presence of an elevated red cell volume, marrow cellularity of greater than 75%, particularly when accompanied by megakaryocytic hyperplasia, of iliac crest aspirate or trephine specimens is sufficient per se to establish a diagnosis of polycythaemia rubra vera.
A one-year-old child who presented with thrombocytopaenia was found to be HIV positive and has now developed persistent generalised lymphadenopathy (PGL).
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Cytogenetic analysis from the bone marrow of a patient with a myelodysplastic syndrome revealed the balanced translocation t(3;5)(q21;q31). Although this translocation has recently been described in six cases of AML, this is the first such observation in a preleukaemic syndrome. Subsequent evolution into RAEB and AML(M2) was noted without the acquisition of additional cytogenetic changes and complete remission achieved with conventional cytotoxic chemotherapy. The relationships with other acquired abnormalities of chromosomes 3 and 5 in MDS/AML are discussed.
Unresponsiveness to skin testing with PPD and tetanus toxoid was commonly seen in patients with haemophilia A but not infected with human immunodeficiency virus but was uncommon in controls. Vaccination history indicated that the unresponsive patients had not been immunised in childhood. Other tests of immune competence (skin tests with other antigens, lymphocyte stimulation with mitogens and antigens, and viral serology) showed that the haemophilia A patients had an adequate response to pathogens to which they had been exposed. Five of 12 such patients had a mild T4 lymphopenia, and this may have been related to parenteral administration of large quantities of protein.
A one-year-old child who presented with thrombocytopaenia was found to be HIV positive and has now developed persistent generalised lymphadenopathy (PGL).
Inflammatory polymyositis can be precipitated by acute febrile illness of viral origin, but similar association with pyogenic bacterial illness is not recognised. We describe two cases in which recovery from staphylococcal septicaemia was complicated by a widespread inflammatory myopathy.
Both murine cuprozinc and manganosuperoxide dismutases were purified to electrophoretic homogeneity from liver; the former (dimer) had a sp. act. of 2600 U/mg and a subunit mol. wt. of 17,000, the latter (tetramer) 2300 U/mg and mol. wt. 23,000. Heterologous radioimmunoassays had sensitivities of 3.1 ng/ml for the former enzyme and 2.5 ng/ml for the latter, and were appicable across murine genetic lines (Balb/c, ob/ob, db/db). Islets had the lowest concentrations of both enzymes among the tissues studied, and this could explain their vulnerability to free-radical damage.
Investigation of the control of glucagon secretion has suffered from the lack of suitable in vitro models. The present studies were initiated to further validate the use of organ cultured islets for such investigation and to develop methods for obtaining rat islets relatively depleted of B cells. Rat islets maintained in tissue culture for 1 week are shown to respond to glucose, epinephrine, acetylcholine, arginine, and somatostatin in a physiologic manner. High glucose concentration during culture is associated with increased glucagon secretion despite increased insulin secretion. Treatment of rats with diabetogenic agents just prior to islet isolation results in B-cell deterioration during culture and insulin content about 20% normal after 1 week of culture. B-cell depleted islets show no glucagon suppression by glucose despite the presence of insulin.
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The use of splenic radiotherapy in the treatment of hairy-cell leukaemia is discussed. Reference is made to the case of an elderly female whose cardiorespiratory state precluded splenectomy, and who responded well to splenic irradiation on two occasions.
Administration of the antioxidant vitamin E to rats, prior to administration of either streptozotocin or alloxan, provided protection against the diabetogenic effect of both these agents. This was demonstrated by their response to a glucose load, their pancreatic insulin content and light microscopy findings. In addition, rats whose antioxidant state was depleted, by being maintained on a vitamin E and selenium-deficient diet, demonstrated increased diabetogenic susceptibility to normally nondiabetogenic doses of streptozotocin. These findings provide indirect support for the suggestion that the chemical agents streptozotocin and alloxan may exert their diabetogenic effect by acting as oxidants or free radical producers.
Suerpoxide dismutase was administered intravenously to rats 50 min prior to intravenous administration of a diabetogenic dose of streptozotocin. A dose of 45 mg/kg streptozotocin alone produced marked glucose intolerance and a decrease in pancreatic insulin content to less than 10% of control; both of these effects were abolished by prior administration of 105 mu/g of superoxide dismutase. Superoxide dismutase (105 mu/g) administered 50 min before 65 mg/kg intravenous streptozotocin did not prevent the development of diabetes. The fall in pancreatic insulin content seen with streptozotocin alone was, however, partially reversed by superoxide dismutase.
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