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Biomedical subjects

R M Lyons

Publications and source records attributed to R M Lyons.

44 records · Page 3Linked to original sources
PubMed1978

Rheumatoid factor interference with the latex agglutination test for fibrin degradation products.

The latex agglutination test for FDP is widely employed clinically to aid in the diagnosis of DIC and other conditions. Of sera containing RF, 93% demonstrated positive FDP latex agglutination tests. Reducing agents in all instances destroyed the RF agglutinating capability. Futhermore, 86% of sera positive for FDP and RF became FDP-negative following reduction. Therefore RF was responsible for false-positive FDP latex agglutination tests in the majority of patients. Reduction of patient sera is a rapid, simple method to distinguish a positive FDP test from a false-positive due to RF.

Arthritis↗
PubMed1977

Development of chronic myelocytic leukemia during the course of acute lymphocytic leukemia in an adult.

A 59-year-old patient is described who presented with acute lymphocytic leukemia. Complete remission was induced rapidly with vincristine and prednisone. Nine months later he acquired the clinical and hematological picture of a myeloproliferative disease, and bone marrow cytogenetic studies demonstrated the presence of the Philadelphia chromosome. Within 4 months he again developed overt acute lymphocytic leukemia and died. Several lines of evidence have recently indicated a relationship between myeloproliferative and lymphoproliferative disorders, particularly chronic myelocytic and acute lymphocytic leukemia. This patient's course is another example of that association.

Bone Marrow↗
PubMed1975

Thrombin-induced protein phosphorylation in human platelets.

Intact human platelets loaded with 32PO4 contain multiple phosphorylated proteins. Thrombin treatment of intact 32PO4-loaded platelets results in a 2-6-fold increase in phosphorylation of a platelet protein (designated "peak 7" protein) of approximately 40,000 mol wt as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and by gel filtration on Sephadex G-150. A similar increase in phosphorylation was observed in a platelet protein (designated "peak 9" protein) of approximately 20,000 mol wt. The time for half-maximal phosphorylation of peak 7 and peak 9 protein was 10-14 s. The concentration of thrombin at half-maximal phosphorylation was 0.25 U/ml for both proteins. Prior incubation of platelets with dibutyryl cyclic adenosine 3',5'-monophosphate or prostaglandin E1 inhibited thrombin-induced peak 7 and peak 9 protein phosphorylation. The erythroagglutinating phytohemagglutinin of Phaseolus vulgaris, a non-proteolytic release-inducing agent, induced peak 7 and peak 9 protein phosphorylation. Thus, the characteristics of peak 7 and peak 9 protein phosphorylation are similar to those of the platelet release reaction, suggesting that the phosphorylation of these proteins may play a role in the platelet release reaction. When platelet sonicates or the supernatant fraction from platelet sonicates were incubated with [gamma-32P]ATP there was phosphorylation of both peak 7 and peak 9 proteins. This phosphorylation was unaffected by either added thrombin or adenosine 3',5'-cyclic monophosphate (cAMP) despite the presence of the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine. Thus, the thrombin-dependent phosphorylation depends upon intact platelets. When the supernatant fraction from platelet sonicates was fractionated by histone-Sepharose affinity chromatography, two distinct protein kinase enzymes were resolved, one a cAMP-dependent holoenzyme and the other a cAMP-independent enzyme. The isolated cAMP-dependent enzyme fraction catalyzed the cAMP-(but not thrombin-) stimulated phosphorylation of a protein that co-electrophoresed with peak 7 protein.

Animals↗
PubMed1975

Gamma heavy chain disease: rapid, sustained response to cyclophosphamide and prednisone.

A patient, CAL, with gamma heavy chain disease is presented who has had a complete remission lasting over 2 yr with combination chemotherapy consisting of pulsatile cyclophosphamide and prednisone. The patient exhibited many features of an atuoimmune process including a vasculitis, low serum complement levels, a positive antiglobulin (Coombs) test, Raynaud's phenomenon, and keratoconjunctivitis sicca. The CAL paraprotein was found to have several previously undescribed characteristics. It reacted with antisera to Fd, Fab, and Fab', suggesting that most of the Fd portion of the molecule was intace. CAL protein consists of two polypeptide chains of molecular weight 49,000 covalently linked to form a dimer of 95,000 molecular weight. The covalent linkage suggests that the hinge region of this gamma heavy chain is intact.

Bone Marrow Examination↗
PubMedDate not supplied

Controversies in antithrombotic therapy for patients with mechanical heart valves.

Current anticoagulation guidelines for patients with mechanical heart valves are based on studies that are seriously flawed in that they used prothrombin time ratios rather than the international normalized ratio (INR) and failed to consider the level of anticoagulation actually achieved. Available data suggest that the appropriate INR range varies according to risk factors and that "tight control" of the INR is of critical importance in reducing thromboembolic and hemorrhagic events. Whether antiplatelet therapy adds benefit to an appropriately controlled level of anticoagulation is not clear. During pregnancy, warfarin is contraindicated; adjusted-dose heparin is recommended by published American and European guidelines. Even so, one small study suggests that this may be inadequate. Topical antifibrinolytic agents can negate the need to alter systemic anticoagulation during dental surgery.

Anticoagulants↗