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Biomedical subjects

E Fukada

Publications and source records attributed to E Fukada.

At least 19 recordsLinked to original sources
PubMed1996

Enhancement of bone formation by drawn poly(L-lactide).

Poly(L-lactide) (PLLA) was molded into films and rods, and drawn in the longitudinal direction to endow them with piezoelectricity. The piezoelectric constants of PLLA films increased with the draw ratio and, after passing a maximum at a draw ratio around 5, decreased. PLLA samples with a draw ratio 5 underwent fibrilization. The PLLA rods were intramedullarily implanted in the cut tibiae of cats for internal fixation up to 8 weeks. Fracture healing was clearly promoted with increased callus formation as the draw ratio of the PLLA rod increased, whereas the undrawn PLLA as well as a polyethylene control rod had no effect on callus formation, or rather, retarded it. This finding strongly suggests that the promotion of fracture healing by fixation with drawn PLLA can be ascribed to the piezoelectric current generated by the strains accompanying leg movement.

Animals↗
PubMed1989

Blood modeling using polystyrene microspheres.

The steady flow viscosity at shear rates 0 to 120 sec-1 and dynamic viscoelasticity at frequencies 0.02 to 0.8 Hz were determined for aqueous suspensions of uniform polystyrene microspheres of 1.0 micron diameter. Rheological properties of the microsphere suspensions were Newtonian for particle concentrations up to 32%. By introducing dextran and calcium chloride into the particle suspensions, non-Newtonian behavior was produced similar to that observed for human blood. The cooperative effects of dextran and calcium ions promoted aggregation of particles at a concentration as low as 12%. Thus, a suspension of uniform sized spherical polystyrene particles in aqueous solution of dextran may be made to mimic blood by controlling the surface charge on the polystyrene spheres using addition of calcium ions to the medium.

Blood↗
PubMed1988

Bending piezoelectricity in a microbially produced poly-beta-hydroxybutyrate.

An optically active polymer, poly-beta-hydroxybutyrate (PHB), is produced in cytoplasm of various vacteria. The bending piezoelectric effect was observed in oriented films of PHB. The coefficient between the electrical polarization and the stress gradient was found to be in the order of 10(-18) Cm/N, which was similar to the value reported for bone. Anisotropy in the value of the coefficient was also observed.

Electrochemistry↗
PubMed1986

Quick diagnosis of malignant melanoma with the touch-fluorescence method during operation.

Nine cases of primary melanotic melanoma, three cases of metastatic amelanotic melanoma, and 26 cases of pigmented and unpigmented tumors other than melanoma were examined with the touch-fluorescence method using preparations from the cut surface of the lesions. Fluorescent melanoma cells were easily detected with a fluorescence microscope in all the cases of malignant melanoma whether the melanoma was melanotic or amelanotic. The fluorescent melanoma cells could be divided into three types by configuration: round, spindle-shaped, and pleomorphic. The main cell type of superficial spreading melanoma was round and that of nodular melanoma and acral lentiginous melanoma was chiefly pleomorphic. Fluorescent tumor cells were not seen in pigmented and unpigmented tumors other than melanoma, except in pigmented basal cell epithelioma; this fact made it possible to apply this method routinely for quick diagnosis of malignant melanoma during operation.

Adult↗
PubMed1986

Effect of pulsing electromagnetic fields on DNA synthesis in mammalian cells in culture.

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.

Animals↗
PubMed1984

Electro-biorheology.

Studies on piezoelectricity in biopolymers are reviewed with some examples. By measuring anisotropy of elastic and piezoelectric constants in fish skin, the direction of preferred orientation of collagen fibers is determined. Temperature and moisture dependence of real and imaginary parts of the piezoelectric constant observed for oriented film of fibrin gel indicates that temperature-time equivalence holds for the piezoelectric relaxation. The piezoelectric constant for oriented film of polyhydroxybutyrate decreases above glass transition temperature, which is related to the elastic and dielectric relaxations. When alpha-helical molecules of poly-gamma-methyl-L-glutamate are electrically oriented in ethylene dichloride solution and shear stress is given by ultrasound, the piezoelectric polarization is observed. When the film of poly-gamma-methyl-glutamate is wrapped around the femur of rat, the formation of new bone is produced.

Animals↗
PubMed1984

Methods to study rheological properties of blood during clotting.

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.

Animals↗
PubMed1984

Dynamic evaluation of aggregation and agglutination of red blood cells.

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.

Animals↗
PubMed1983

Cysteinyldopa isomers and dopa in lesions and urine of Japanese patients with malignant melanoma.

Cysteinyldopas and Dopa in the urine and tissues of Japanese melanoma patients were investigated quantitatively by means of high-performance liquid chromatography. Cysteinyldopa isomers were detected in the urine of eumelanic Japanese patients. The amount (X +/- SD%) of each isomer of cysteinyldopa in the urine was 80.26 +/- 4.66% in 5-S-cysteinyldopa, 9.39 +/- 1.64% in 2-S-cysteinyldopa, 7.07 +/- 3.33% in 2, 5-S, S-dicysteinyldopa, and 3.28 +/- 1.43% in 6-S-cysteinyldopa. The amount of cysteinyldopa in melanoma tissues was 26-314 times more than that of Dopa. The amount (X +/- SD%) of cysteinyldopa in the tissues was 80.34 +/- 1.75% in 5-S-cysteinyldopa, 11.06 +/- 1.91% in 2-S-cysteinyldopa, 6.27 +/- 1.43% in 2, 5-S, S-dicysteinyldopa, and 2.34 +/- 0.61% in 6-S-cysteinyldopa. The fact that the percentages of each isomer of cysteinyldopa in the urine and in the tissues were approximately constant suggests that the cysteinyldopas secreted from melanoma cells were excreted into the urine without being metabolized.

Cysteinyldopa↗
PubMed1983

Studies on amelanotic melanoma with the fluorescence method (Falck and Hillarp) and biochemical analysis of 5-S-cysteinyldopa in the tissues.

Histochemical findings of primary and metastatic amelanotic melanomas were shown by the formaldehyde-induced fluorescence method (Falck and Hillarp). All or some of the amelanotic melanoma cells were discovered to emit green specific fluorescence. Results of the determination of 5-S-cysteinyldopa and DOPA in amelanotic melanoma tissues indicated that the specific fluorescence emitted by these cells is primarily due to the presence of 5-S-cysteinyldopa. The values of 5-S-cysteinyldopa in these tissues were lower than those in melanotic melanoma, but were approximately the same as those in pigmented nevus. When unpigmented tumors were histopathologically revealed to be malignant, amelanotic melanoma could be definitely diagnosed by the fluorescence method of Falck and Hillarp and the biochemical analysis of 5-S-cysteinyldopa in the tissues.

Adult↗