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Biomedical subjects

D L Lawson

Publications and source records attributed to D L Lawson.

46 records · Page 3Linked to original sources
PubMed1985

Influence of selective thromboxane synthetase blocker CGS-13080 on thromboxane and prostacyclin biosynthesis in whole blood: evidence for synthesis of prostacyclin by leukocytes from platelet-derived endoperoxides.

Increase in thromboxane A2 (TXA2) generation has been proposed as a mechanism of dynamic vaso-occlusion and in vivo platelet thrombus formation. We have examined the effects of CGS-13080, an imidazole derivative, on rabbit and human TXA2-prostacyclin (PGI2) "balance." In rabbits given CGS-13080, serum levels of TXB2 (stable metabolite of TXA2) were inhibited 81% at 2 hours and 56% at 24 hours (both P less than or equal to 0.01). Collagen-induced platelet aggregation was inhibited at 2 hours after CGS-13080 administration. In contrast, serum levels of 6-keto-PGF1 alpha (stable hydrolysis product of PGI2) increased 587% compared with control values at 2 hours (P less than or equal to 0.01). Platelet and white blood cell counts were not significantly altered. In human blood incubated in vitro with CGS-13080, serum TXB2 was completely inhibited, whereas PGI2 generation was stimulated (both P less than or equal to 0.001). In other experiments, we demonstrated uptake of platelet-generated cyclic endoperoxides by leukocytes and generation of PGI2 in the presence of CGS-13080 but not indomethacin. Thus, CGS-13080 inhibits TXA2 and stimulates PGI2 production in rabbit and human blood. Increase in PGI2 generation with TXA2 inhibition may be of potential benefit in conditions characterized by platelet hyperactivity.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Surface Ia-like expression and MLR-stimulating capacity of human leukemic myeloblasts: implications for immunotherapy and prognosis.

Surface Ia-positive cells were found to vary from 0 to 100% in initial blood specimens from 37 adults with acute myelogenous leukemia (AML). When myeloblasts from 19 patients were tested against panels of lymphocytes from 5 to 19 normal donors, mean stimulation indices ranged from 1 to 60. Some leukemic myeloblasts strongly stimulated most allogenic responder lymphocytes whereas others produced almost no stimulation. The addition of antibody against human Ia to 28 mixed leukocyte reaction (MLR) combinations resulted in significant inhibition (p less than 0.001) of 3H-thymidine incorporation. Testing of myeloblastic Ia may have clinical relevance because patients with greater than 50% Ia-positive myeloblasts had a significantly longer survival than patients with fewer Ia-positive myeloblasts (p less than 0.04).

Adult↗
PubMed1978

Semiquantitative computerized image analysis of fetal hemoglobin distribution patterns in sickle cell anemia and its variants.

Computerized, semiquantitative image analysis of 2913 erythrocytes from 29 young patients with sickle cell anemia and its variants was conducted utilizing a modified method for determination of fetal hemoglobin distribution by an acid elution procedure. Histograms of eight arbitrary levels of staining intensity, proportional to fetal hemoglobin levels, were analyzed in relationship to both computer-generated, mathematical parameters of erythrocytic shape abnormalities and clinical parameters of disease severity. Shifts in fetal hemoglobin distribution were observed in analysis of sequential specimens. An inverse correlation was observed between angularity of erythrocytes and their individual fetal hemoglobin content (p less than or equal to 0.05). A positive correlation was noted between growth percentiles and percentage erythrocyte ghosts by acid elution (p less than or equal to 0.01).

Anemia, Sickle Cell↗
PubMed1977

Cerebrospinal fluid polyamine monitoring in central nervous system leukemia.

High-pressure chromatographic analysis of cerebrospinal fluid utilizing the o-phthalaldehyde-fluorescent detection system allows the reproducible detection of acid-soluble polyamines in this extracellular fluid compartment. Measurements made by this method in childhood acute lymphocytic leukemia appear to correlate with the remission-relapse status of the patient. The sensitivity of this analytic technique may allow much earlier detection of central nervous system disease. Studies are presently under way in our laboratories to define the usefulness of this technique to monitor successful chemotherapy of leukemia patients.

Adolescent↗
PubMed1977

Bone marrow polyamines in children with acute leukemia as related to remission status, therapy, and cellularity of specimens.

Measurements of polyamines have potential practicality as biochemical markers of disease activity in adult cancer patients. On this basis, similar measurements were made in children with leukemia and solid tumors. Fluctuations in blood polyamine concentration were studied in relationship to chemotherapy schematics, cellularity and composition of blood and bone marrow specimens, and remission status of patients. Our results indicate that each of these factors may influence these determinations and consequently their clinical usefulness.

Adolescent↗
PubMed1975

'Ambidexterity' in bat wings as evidenced by bone weight.

1. Comparable right and left wing bones of three species of bats failed to demonstrate one-sided dominance, although such dominance is widespread in tetrapods. 2. When similar units are compared, some of the bones from one side are heavier, some are lighter, than those from the other side. This appears to represent a compensatory mechanism for achieving balanced weight and propulsion. 3. The criterion used by Dogra & Singh (1971) for deciding whether or not a difference exists between comparable units (i.e. that an observed difference in weight is 'real' if the difference is at least one per cent of the weight of the greater element) is not statistically valid in the three species of bats used in this study. Sole use of this criterion to determine one-sided dominance can therefore be misleading.

Animals↗