Biomedical subjects
Publications and source records attributed to M Date.
Exposures of Chinese hamster cells to pulsing electromagnetic field (PEMF) with 0.18-2.5 mT did not influence the baseline frequency of sister-chromatid exchanges (SCE). The results suggest that PEMF with the magnetic intensity examined does not interfere with DNA replication nor produce DNA lesions, thereby leading to an increased frequency of SCE.
DNA synthesis in Chinese hamster V79 cells was significantly enhanced when they were exposed to weak, pulsing electromagnetic fields generated by specific combinations of the pulse width (25 microseconds), frequency (10, 100 Hz) and magnetic intensity (2 X 10(-5), 8 X 10(-5) T). Conversely the DNA synthesis of cells in the fields at 4 X 10(-4) T was repressed to 80% of that in controls not exposed to the fields.
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In order to attempt in vitro evaluation of antithrombogenecity for materials of artificial blood vessel tube, a new type of rheometer was developed. The rheometer originally consists of a cylindrical tube suspended from a torsion wire and filled with blood. The tube is excited in torsional oscillation and subsequent damped oscillation is observed. The apparatus can sensitively follow the change of fluidity during coagulation of blood. The damped oscillation curves during coagulation for fibrinogen - thrombin solution and blood put in a cylindrical tube made of the artificial material were measured. For fibrinogen - thrombin solution with lower fibrinogen and thrombin concentrations, the values of logarithmic damping factor (LDF) during coagulation increased and then decreased through a maximum. For blood and fibrinogen-thrombin solution with the higher concentrations of fibrinogen and thrombin, LDF monotonously decreased with the progress of coagulation. With a glass tube, the decrease of LDF for whole blood taken without anticoagulant rapidly occurred within about 15 min after sampling, while, with expanded polytetrafluoroethylene (EPTFE; Goar tex) and polydimethylsiloxane (Silastic) tubes, the decrease of LDF proceeds over 40-60 min. The present method is probably available for in vitro evaluation of anticoagulability or antithrombogenecity of artificial materials.
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In vitro rheological studies on clotting of fibrinogen solution, plasma and blood are reviewed. Multiple viscoelastorecorder (MVER) and viscoelastorecorder (VER) were developed for determining the dynamic rigidity modulus (G') and loss modulus (G") during clotting. The effect of some parameters on clotting and the properties of fibrin clot are discussed. The parameters include measuring frequency, measuring shear strain and surface coating of measuring cell. The change of dynamic rigidity during clotting was compared between normal plasma and plasma from patient with Glanzmann's disease. By detecting the stress at the higher harmonic frequency, the non-linear terms of G' and G" were determined.
Viscoelastic evaluation of aggregation and agglutination of red blood cells was attempted. A concentric double cylinder viscoelastometer was used for determining the dynamic rigidity modulus and loss modulus of blood sample. The dynamic rigidity modulus of horse blood were measured over a wide range of hematocrit. The relation between the viscoelastic behavior and the erythrocyte sedimentation was examined. The change in the amount of surface charge of enzyme treated red blood cells was qualitatively estimated from the measurements of dynamic viscoelasticity of red blood cells suspension with added poly-L-lysine. The dynamic rigidity modulus of red blood cells agglutinated by adding lectin (concanavalin A) were also measured.
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A streptomycete strain, P3409, which produced new basic macrolide antibiotics, deltamycins A1, A2 and A3 and carbomycin A (deltamycin A4) was considered to be a new subspecies for which the name Streptomyces halstedii subsp. deltae was proposed. Deltamycins A1, A2, A3 and A4 which were active against Gram-positive bacteria were produced in organic complex media.
Acetohydroxy acid synthetase [EC 4.1.3.18] of Neurospora crassa has been solubilized from a mitochondrial pellet fraction by sonic treatment in 1.0 M potassium phosphate buffer at pH 7.5 containing 10 mM MgSO4 and centrifugation at 180,000 X g for 20 min. The soluble enzyme thus obtained has a high specific activity and a high sensitivity to valine comparable to the original mitochondrial pellet suspension when the activity was determined in high concentrations of potassium phosphate.
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We demonstrated by ultrastructural examination that the leukemic blasts of 13 patients with acute myeloblastic leukemia (AML) without maturation (M1 in the French-American-British classification) showed heterogeneous features. In 7 patients, the leukemic blasts had a high level of light microscopic myeloperoxidase positivity (> 50%). Ultrastructurally, the cells were myeloblast-promyelocytes with 100% myeloperoxidase positivity, and these 7 patients appeared to have typical AML. In contrast, the remaining 6 patients had leukemic blasts with a low myeloperoxidase positivity (< 50%) and heterogeneous features. Three had ultrastructural features of myelomonocytic or monocytic lineage, 1 had myelomonocytic cells associated with megakaryoblasts, and 1 had undifferentiated blasts. The former group had a better prognosis than the latter, indicating that ultrastructural analysis of M1 leukemia may help predict the response to therapy.