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Biomedical subjects

K Akagi

Publications and source records attributed to K Akagi.

At least 235 records · Page 13Linked to original sources
PubMed1980

Purification and properties of deoxyribonuclease II from human urine.

The acid deoxyribonucleases [DNase II; EC 3.1.4.6] in human urine were purified approximately 400- to 500-fold by phosphocellulose chromatography, gel filtration on Sephadex G-75 and isoelectric focusing, with a total recovery of 22%. The enzymes were present in a least three forms with different isoelectric points, pHs 6.4, 6.6, and 6.8. However, other properties were essentially similar. The enzymes did not require divalent cations for activity, and the optimal pHs were at 5.1 to 5.3 in 33 mM acetate buffer. They had a molecular weight of around 36,000, as estimated by gel filtration on Sephadex G-75. The enzymes were endonucleases which hydrolyzed native, double-stranded DNA about 5 to 15 times faster than thermally denatured DNA. The products formed from native DNA were 3'-phosphoryl- and 5'-hydroxy-terminated oligonucleotides. The average chain length of the limit digests with these enzymes was approximately 11 to 15, and the major fragments were longer than pentanucleotides. The final preparations were free of nonspecific acid and alkaline phosphatases and phosphodiesterase, but contained contaminating ribonuclease activity.

Deoxyribonucleases↗
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↗
PubMed1979

A study of the multiple pinhole coded aperture and the application of the minicomputer in image decoding.

Research has been done on optically reconstructed imaging employing the Multiple Pinhole Coded Aperture (hereafter abreviated as MPCA) in radioisotope tomographic imaging. However, problems remain in the optically reconstructed image method. Therefore, we employed a minicomputer (hereafter abbreviated as CPU) and developed the software for decoding and managing the radioisotope tomographic image. Combining the MPCA and the CPU system, we were able to decode and manage the radioisotope tomographic image. 1) In comparison to the optically decoded MPCA image, various input commands are possibly in the CPU method according to the dialogue between the CPU and the on line typewriter. In addition to this, decoded tomographic images of unrestricted depth are readily attainable. 2) In the CPU method noise elimination and other aspects of image management can be easily performed.

Computers↗
PubMed1978

Purification and properties of deoxyribonuclease from human urine.

The DNAase in human urine was purified about 30-fold with a recovery of 28%. This involved DEAE-cellulose and phosphocellulose chromatography steps and gel filtration on Sephadex G-75. The enzyme required divalent cations such as Co2+, Mg2+, Mn2+ and Zn2+ for activity, but Ca2+, Cu2+ and Fe2+ were ineffective. EDTA and G-actin inhibited the reaction. The maximum activity was observed at pH 5.5 in acetate buffer plus Co2+ or Mg2+ and Ca2+. It had a molecular weight of approximately 38 000, estimated by gel filtration on Sephadex G-75 and isoelectric point of around pH 3.9. The enzyme is an endonuclease which hydrolyzes native, double-stranded DNA about 3 to 4 times faster than thermally denatured DNA to produce 5'-phosphoryl- and 3'-hydroxyl-terminated oligonucleotides. The final preparation was free of non-specific acid and alkaline phosphatases, phosphodiesterase and ribonuclease activities.

Chromatography, Gel↗
PubMed1978

A method of tomographic imaging using a multiple pinhole-coded aperture.

High energy collimators in use today are limited with respect to resolution and efficiency. The multiple pinhole coded aperture (hereafter abbreviated as MPCA) is a method being considered to improve the above. In our study we conducted basic experiments with an MPCA using an Anger-type gamma-camera. Using this method, we were able to perform radioisotope imaging and radioisotope tomographic effect. We have studied the resolution, detection efficiency, and tomographic effects of the MPCA. We found that, in the MPCA, detection efficiency is proportional to the number of pinholes and resolution is dependent upon the pinhole diameter. This tomographic effect is of the same principle as the stretching-type tomography, images on both side of the desired image appearing as noise images, affecting the depth resolution. Using an MPCA with a pinhole diameter of 3 mm and 3 pinholes positioned in an equilateral triangular pattern measuring 7.8 cm on each side, we attained a depth resolution of 3 cm. Because the MPCA method involves complicated image processing, the resulting image contains a factor of 2n-2 (where n is the number of pinhole) of noise, affecting the depth resolution.

Radionuclide Imaging↗