Biomedical subjects
Publications and source records attributed to Y Higuchi.
The crystal structure of aspartate aminotransferase of Escherichia coli was determined by X-ray structure analysis at 2.8 A resolution. The structure was solved by the molecular replacement method and refined to an R-factor of 0.27, and it was found that the overall structure of AspAT of E. coli is similar to that of those of higher animals.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Mouse and rat myeloma cell lines showed little or no rosette formation with sheep erythrocytes (SRBC) coated with rabbit IgG (rabbit EA) but showed marked rosette formation after treatment with trypsin, pronase or neuraminidase. These cell lines showed no rosette formation with SRBC coated with mouse IgG (mouse EA): treatment with trypsin enabled the detection of rosettes among the mouse myeloma cell lines but not by the rat myeloma cells. The F(ab')2 fragment of the anti-Fc receptor II antibody blocked the formation of rosettes with rabbit EA by mouse myeloma cell lines after treatment with trypsin. Aggregated mouse IgG1 and IgG2b subclasses strongly inhibited the formation of rosettes with rabbit EA, whereas aggregated mouse IgG2a showed a marginal inhibitory effect. A large amount of mouse IgG2a, however, caused significant inhibition. Our results also revealed that aggregated mouse IgG could bind to the rat myeloma cell line. The Fc rosette forming abilities of the enzyme-treated mouse and rat myeloma cells became reduced after cultivation both in the presence and absence of FCS but not after cultivation in the presence of cycloheximide, suggesting that cell surface substances, which may be glycoprotein that incompletely mask Fc receptors, are produced by myeloma cells.
Unique hybrids (HINS and CANS lines) between macrophages and a myeloma cell line, NS1 initially expressed myeloma functions but later expressed active macrophage functions together with constitutive expression of c-fos gene. Enhancement of c-fos transcription was also observed in activated mouse peritoneal macrophages, and a range of macrophage-stimulating substance was found to induce c-fos transcription kinetic unique to each stimulator including immediate, delayed and prolonged responses in aged HINS-B3 cells, which displayed low levels of steady-state c-fos transcription. It was also found that a significant enhancement of c-fos transcription followed restimulation with either interferon gamma (IFN gamma) or lipopolysaccharide (LPS) after an initial IFN gamma stimulation. Thus it appeared that enhanced c-fos expression was closely connected with macrophage activation. On the other hand, macrophage stimulators suppressed [3H]thymidine incorporation into aged HINS-B3 cells. These results may simply suggest that c-fos expression contributes to macrophase activation but not to cell proliferation. However, it is also possible to speculate that c-fos expression contributes to cell proliferation as a salvage system operating to overcome the suppression during the macrophage activation.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The hydrogenase solubilized from the particulate fraction from Desulfovibrio vulgaris Miyazaki F (IAM 12604) has been crystallized. Although the solubilized hydrogenase purified by the previous method (Yagi, T., Kimura, K., Daidoji, H., Sakai, F., Tamura, S., and Inokuchi, H. (1976) J. Biochem. (Tokyo) 79,661-671) revealed a single band upon disc electrophoresis, it could not be crystallized. The apparently homogeneous hydrogenase has been separated into three components of similar molecular weights by high performance liquid chromatography on DEAE-Toyopearl. Each hydrogenase component was successfully crystallized by means of the vapor diffusion method with polyethylene glycol or 2-methyl-2,4-pentanediol as a precipitating agent. Seeding procedure is necessary to grow an x-ray grade crystal. Preliminary x-ray experiments reveal that crystals grown from one component are in space group of P2(1)2(1)2(1) with a = 102.1(1), b = 126.8 (3), and c = 66.9(1) A. The unit cell volume of 8.66 X 10(5) A3 suggests that it contains one molecule/asymmetric unit (Vm = 2.43). The crystals grown from another component are in the same space group with a = 99.6(1), b = 126.8(3), c = 66.9(1) A, and the unit cell volume is 8.45 X 10(5) A3 (Vm = 2.37). The crystals diffract more than 2.5 A and are suitable for complete crystal analysis. Up to 4 A resolution native data have been collected on a diffractometer.
Explore the source record for details and available documents.
The aspartate aminotransferase of Escherichia coli was overproduced in cells after genetic manipulation, and was crystallized from a polyethylene glycol solution, pH 7.0. The crystals obtained were of good quality and had diffractions extending beyond 2.4 A. The space group and unit cell dimensions were determined with a precession camera and a four-circle diffractometer to be C222(1), and a = 157.1 A, b = 85.5 A, and c = 79.7 A, respectively. Only one protein subunit is contained in an asymmetric unit.
Several parts of the cerebral cortices in five brains from patients with Alzheimer's disease were examined by light and electron microscopes. The results obtained are as follows: The initial change of the cerebral cortex in the brain occurred in the small blood vessel and capillary. The endothelial cell of the blood vessel fell into a degenerated state with swelling of the vascular feet and astroglial cells. The change in a great number of nerve cells and their processes diffusely observed in the cortices were nonspecific and could be due to primary vascular degeneration. Severe dementia in Alzheimer's disease seemed to be well explained by the histopathological findings of diffusely destroyed nerve cells and their processes. From this, Alzheimer's disease can be speculated to be a disease caused by progressive capillary degeneration.
201Tl/67Ga crude uptake ratio (CUR) was measured in 12 patients with small cell carcinoma of the lung (SCCL); it was further compared with serum neuron-specific enolase (NSE) and the actual survival times. A significant inverse correlation was observed between CUR and serum NSE (r = 0.610; p less than 0.05); CUR also correlated with actual survival time (r = 0.605; p less than 0.05). Oat cell-type SCCL having a low CUR and highly raised serum NSE, showed a poorer prognosis than the other subtype which has a high CUR whose serum NSE was not raised as much as in oat cell-type SCCL. This preliminary study suggests that 201Tl/67Ga uptake ratio is a possible prognostic indicator of SCCL.
In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compared with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Cytochrome c553 from the sulfate-reducing bacterium, Desulfovibrio vulgaris Miyazaki, has been crystallized. The combination of microdialysis and vapor diffusion allowed successful crystallization. The crystals were of good quality, and useful data were obtained that extended to the nominal resolution of 1.3 A. The space group is P4(3)2(1)2 with cell dimensions of a = b = 42.7 A, c = 103.4 A. More than twenty heavy-atom reagents were screened with the isomorphous replacement technique, and only the mersalyl derivative could be used for the phase determination. The single isomorphous replacement method combined with the anomalous scattering effect of the Hg-atom in mersalyl and the Fe-atom of the heme group was used for the phase determination.