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Biomedical subjects

I Seo

Publications and source records attributed to I Seo.

11 recordsLinked to original sources
PubMed1990

[The forming phase and various properties of Au, Ag, Cu and Ga mixture in metal fired crowns].

A new time-saving method has been developed to produce artificial crowns without using the casting process. Plastic mixtures of gallium and other metal particles are kneaded into desired shape and then heated for hardening. By this method, the time required for hardening and producing restorative materials has been shortened greatly. In the present experiment, gallium was triturated with powdered gold, silver and copper to make binary alloy samples. The dimensional change was measured between heat treatment. After heat treatment, the test piece was examined for compressive strength, compressive shrinkage, hardness, tarnishing and difference in phase. Non-heated and heated alloy specimens (Au-Ga, Ag-Ga, Cu-Ga) expanded to form the new phase. The ability of Au-Ga samples to bear compressive strength, when heated at 300 degrees C or more (AuGa2----AuGa), became 2.6 times greater than that of non-heat-treated specimens. The compressive strength of Ag-Ga samples dropped briefly at 350 degrees C (Ag0.72Ga0.28----Ag3Ga) but increased at 450 degrees C (Ag3Ga----AgGa). The strength of Cu-Ga pieces fell by half at 475 degrees C and upward (CuGa2----unknown phase). A compression test showed that the contraction percentage of Au and Ag specimens became large as a result of heat treatment, while that of Cu alloys remained almost unchanged. The results of a hardness test (HV) were comparable to those of the compressive strength test. The Au-Ga alloys increased in hardness after high-temperature treatment. In the Ag-Ga alloys, hardness declined at 350 degrees C and increased at 450 degrees C. There was no difference in hardness between Cu specimens after heat treatment and those allowed to stand at room temperature. A tarnishing test revealed that Au-Ga samples turned slightly yellowish. In the case of Ag-Ga samples, the reflectivity Y (%) dipped slightly but discoloration was not recognizable. However, the Cu-Ga samples which were heated at temperatures of up to 280 degrees C showed a slight drop in reflectivity, but those heated at temperatures higher than 280 degrees C decreased to 50-66% in reflectivity and turned black.

Copper↗
PubMed1984

Magnetic resonance imaging of neuroblastoma with a 0.15-T magnet.

Magnetic resonance imaging (MRI) in nine children with neuroblastoma showed that MRI can effectively demonstrate primary and metastatic disease and aid in predicting tumor resectability. MRI can show changes in tumor size and intensity in response to chemotherapy or radiation therapy. Neuroblastomas have an image intensity much lower than that of liver and muscle on inversion-recovery scans. On spin-echo 500/30 scans, the tumors have a greater intensity than muscle and a similar or slightly greater intensity than liver. On spin-echo 1000/60 scans, they are always of greater intensity than liver or muscle. At this stage, the overall accuracy of MRI as compared with other imaging methods is not known.

Adrenal Gland Neoplasms↗
PubMed1983

Basic and clinical evaluation of the measurement of bone resonant frequency.

A new computerized apparatus was constructed to measure the resonant frequency of human ulna in vivo with high sensitivity and reproducibility. Experimental studies using aluminum bar and dried human bone revealed the importance of the ulna being positioned parallel to the radius, approximately 90 degree flexion of the elbow joint, and minimal muscle activity in order to demonstrate maximum resonant frequency of ulna. Measurement of bone resonance in monkeys in vivo and after removal of the bone in vitro showed good agreement. Product of F (maximum resonant frequency in Hz) and L (ulnar length in cm), FL, indicating the speed of propagation of sound wave through the ulna, showed a significant positive correlation with bone mineral content/bone width (BM/BW) measured by Norland-Cameron apparatus and age-bound decline in both sexes. Patients with osteomalacia and primary hyperparathyroid bone disease tended to have higher FL values than expected from BM/BW. Two-dimensional display of FL and BM/BW thus appears to be useful in distinguishing osteoporosis from osteomalacia better than the use of BM/BW alone.

Adolescent↗
PubMed1980

Tc-99m-pyrophosphate accumulation on prosthetic valves.

Tc-99m-stannous pyrophosphate myocardial imaging has been one of the most effective and sensitive procedures for detection of acute myocardial infarction since Bonte et al introduced it in 1974. However, many causes of false-positive studies have also been reported since then. Presented here is an abnormal case of a patient with aortic and mitral valve replacement.

Aortic Valve↗
PubMed1980

[A study of the quantification of (201)TI myocardial scintigrams of prior myocardial infarctions and their influence on left ventricular function (author's transl)].

(201)TI myocardial scintigraphy was performed on 25 cases of prior myocardial infarction, and based upon phantom experiments, the infarct size was quantitatively analyzed as a defect segment percentage (DS%). DS% was compared to the left cardiac function obtained from myocardial scintigrams, RI angiocardiograms, and chest X-ray films, and the results were examined. There was a high degree of correlation between DS% and LVEF and LVEDV/ m(2) (R=-0.72, 0.84). Where DS% was less than 25%, the left ventricular function was almost normal, and where DS% was greater than 25%, deterioration could clearly be seen. There was a correlation between left ventricular volume from myocardial scintigrams and heart volume from chest X-ray films. The (201)TI uptake in the lung field from myocardial scintigrams increased as the infarct size increased, and the uptake in the upper lungs also increased.

Adult↗