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Biomedical subjects

K Sugimoto

Publications and source records attributed to K Sugimoto.

At least 613 records · Page 34Linked to original sources
PubMed1982

Thermodynamics of association of 8-substituted riboflavins with egg white riboflavin binding protein.

Association constants of 14 species of riboflavin derivatives with hen egg-white riboflavin binding protein were measured by a fluorometric titration method using flavin and protein fluorescence in a temperature range of 10--42 degrees C. The derivatives were riboflavins whose 8-CH3 group was substituted with alkylamino, alkyloxy, halogen or hydrogen. The flavin derivatives were classified into four groups, i.e., RR'N, HRN, RO, and halogen, on the basis of the linear relation between enthalpy and entropy changes (linear free energy relationship), and from the chemical structures of the 8-substituents. The relation between the entropy change and the bulkiness of 8-substituents suggested burying of the substituents in a cavity of the protein, and provided an indication of the size of the substituent-accepting cavity. The relation also suggested an electric repulsion between halogen substituents and the binding site. A very good correlation was found between the constant term of the linear free energy relation and the wavelength of the visible absorption peak of flavins, and this correlation suggested the electronic nature of the flavin-protein interaction.

Carrier Proteins↗
PubMed1982

Thermodynamics of association of egg yolk riboflavin binding protein with 8-substituted riboflavins. Comparison with the egg white protein.

The association constants of hen egg yolk riboflavin binding protein with 8-substituted riboflavins were measured using a fluorometric titration method in the range of 10-40 degrees C, and thermodynamic parameters were calculated using ordinary methods. The flavins used were riboflavins whose 8-methyl group was substituted with HRN, RR'N, RO type groups, or halogen atoms. From a plot of delta H degrees against delta Su (unitary entropy change), the flavins were classified into four groups, i.e., HRN, RR'N, RO, and halogen type substituents. In each group, the linear free energy relationship, delta H degrees = u . delta Su+v (u and v were constants specific for each group), was found to be similar to that for egg white riboflavin binding protein, though with different specific constants for each egg protein. The relation between delta Su and the bulkiness (molecular volume) of 8-substituents suggested burying of the 8-substituents in a cavity of the protein similar to that of the egg white protein, but of smaller volume. The behavior of the halogen group was similar to that of the other three groups, and could be explained in terms of the bulkiness of the substituents rather than by assuming electric repulsion between halogen substituents and the binding site, which is in contrast with the case of egg white protein. A linear relation between v value and the wavelength of the visible absorption peak of flavins wa also found.

Animals↗
PubMed1982

A simple bile-disk method for the identification of Bacteroides fragilis.

A simple method for the separation and identification of Bacteroides fragilis from other Bacteroides species through the use of oxgall-impregnated filter paper disks is described. As in the antibiotic sensitivity test, filter paper disks containing defined amounts of bile salt were placed on a lawn of bacterial cells on Gifu anaerobic medium agar plates. Bile-resistant bacteria were identified as strains of Bacteroides fragilis after incubation in anaerobic jars containing hydrogen and carbon dioxide generators at 35 C for 24 hr. The optimum concentration of bile salt, yielding results very similar to those of the conventional tube method, was determined to be 25 mg per disk, empirically. Since this method is easy to perform, time saving, economical and gives clear results, it may be readily used as a daily routine test in the clinical microbiology laboratory.

Bacteriological Techniques↗
PubMed1981

Nucleotide sequence of the asnA gene coding for asparagine synthetase of E. coli K-12.

We have subcloned the asnA gene of E. coli K-12, a gene coding for asparagine synthetase, from a previously cloned 6 mega-dalton segment of E. coli chromosome containing the DNA replication origin, ori, and asnA. The complete nucleotide sequence of the asnA gene was determined: the region of the structural gene extends 990 base-pairs at nucleotide positions 1434-2423 (see Fig. 3), which codes for a polypeptide of 330 amino-acid residues with a molecular weight of 36,688 daltons. The nucleotide sequences of the promoter and the ribosome-binding site of the gene are also assigned. We discuss the properties of its polypeptide.

Amino Acid Sequence↗
PubMed1981

Absorption of protein molecules by the small intestine of the bullfrog tadpole, Rana catesbeiana.

In the tadpole of the bullfrog, Rana catesbeiana, the absorptive cells of the small intestine are characterized by the presence of invaginations of the surface plasma membrane or pinocytic vesicles in the apical cytoplasm and numerous lysosomes in the supranuclear region. These cytological features suggest that the absorptive cells may be able to ingest some macromolecules or particles. The possibility of macromolecular absorption in this animal was examined by using horseradish peroxidase (HRP) and the electron microscopic cytochemical technique. Exogenous HRP was ingested in the absorptive cells by pinocytosis and then accumulated in multivesicular bodies (MVBs) by the contribution of pinocytic vesicles to MVBs. The pinocytic vesicle changed its shape to have an inner vesicle. Some of the inner vesicles of MVBs seem to have originated from the inner vesicles of pinocytic vesicles. Almost all the MVBs in the subapical region showed HRP activity, but some of them showed no acid phosphatase (AcPase) activity; those in the supranuclear region always showed an intense AcPase activity. Therefore some of the subapical MVBs are heterophagosomes and may be joined with lysosome during the movement toward the supranuclear region. The MVBs with lysosomal enzymes in the subapical or supranuclear region are presumably important sites of intracellular digestion. The results indicate that intracellular digestion may occur in the small intestine of the bullfrog tadpole under natural conditions.

Animals↗
PubMed1981

Mitotic index in gastric carcinoma of the scirrhous type.

For the purpose of studying the clinical and pathological specificities of the scirrhous type in gastric carcinoma, 96 patients with gastric carcinoma were studied according to age, sex, stage, macroscopic types and mitotic index. Scirrhous carcinoma was diagnosed in 45 patients. There were higher incidences of scirrhous carcinoma in the younger generation and among women. In the scirrhous type, the percentage of stages III and IV was higher than that of stages I and II (p less than 0.005). In Borrmann's categories III and IV, patients with the scirrhous type were more numerous than those with the other types. Mitotic indices were 18.4 +/- 8.1 in scirrhous type, 52.8 +/- 13.5 in medullary type, 54.1 +/- 16.9 in intermediate type and 53.3 +/- 11.5 in non-cancerous gastric mucosa. The low rate of mitotic index in those with scirrhous carcinoma was statistically significant compared to those of other types and that of the non-cancerous gastric mucosa (P less than 0.001). Mitotic index is apparently related to the extent and the degree of degeneration of interstitial connective tissue. The speed of the growth of the tumor mass in gastric carcinoma is not so closely related to the mitotic index, and relates to a greater extent the number of dissociated cells entering the digestive canal.

Adenocarcinoma↗