Search PubMed⌕ Search

Biomedical subjects

K Komiyama

Publications and source records attributed to K Komiyama.

At least 145 records · Page 8Linked to original sources
PubMed1986

[The suppressive effect of pyrrole-2-carboxylic acid on platelet aggregation].

In the course of a search for novel antibiotics, an antiplatelet substance was isolated from the fermentation broth of Streptomyces sp. No. 82-85. Thereafter, the active substance was identified as pyrrole-2-carboxylic acid (P2C) by structural studies. The effects of P2C on adenosine diphosphate (ADP)-, arachidonic acid-, collagen- or tumor cell-induced platelet aggregation were examined in vitro and ex vivo. In in vitro studies, P2C (25-100 micrograms/ml) suppressed the aggregation of platelets of normal Wistar rats. The intraperitoneal administration of P2C (200 mg/kg) to rats and rabbits suppressed platelet aggregation induced by ADP, arachidonic acid and collagen when examined for 0.5-3 hours after administration. The agent also suppressed platelet aggregation induced by both mouse syngenic tumors, Meth-A fibrosarcoma and IMC carcinoma in vitro.

Adenosine Diphosphate↗
PubMed1985

Natural killer cells in human colostrum.

The presence of natural killer cells in human colostrum was disclosed with the use of a fluorochrome-labeled monoclonal antibody HNK-1 (Leu-7) that recognizes cells with natural killer and killer activity. Approximately 0.5% of total colostral cells were stained with this reagent. These cells were separated by the fluorescence-activated cell sorter and examined for their morphology by electron microscopy and for their cytotoxic activity against 51Cr-labeled K562 target cells. Two morphological types of natural killer cells were observed in colostrum: the first was represented by large cells with numerous vacuoles but without dense cytoplasmic granules; the second type, which occurred with lower frequency, resembled the large granular lymphocytes associated with natural killer activity in peripheral blood. The HNK-1-positive cells from colostrum displayed low cytotoxic activity against K562 target cells. Incubation of HNK-1-positive cells from peripheral blood with cell-free colostrum resulted in a dose-dependent inhibition of the cytotoxic activity. The functional changes were accompanied by morphological alterations which included degranulation and the formation of numerous vacuoles. The variances in the cytotoxic activity of peripheral blood HNK-1-positive cells suspended in different dilutions of colostrum suggest that this fluid contains humoral factors which modify morphology and function depending on their concentrations.

Blood Cells↗
PubMed1985

Pseudomonas aeruginosa in the oral cavity and sputum of patients with cystic fibrosis.

Patients with cystic fibrosis (CF) are often hosts to colonies of both mucoid and nonmucoid strains of Pseudomonas aeruginosa. The major pathogens for chronic and recurrent pulmonary infection in these patients are the mucoid variants of P. aeruginosa. Of the 31 CF patients studied, 14 patients yielded both mucoid and nonmucoid strains of P. aeruginosa from the various oral ecologic sites and saliva. Of the sites tested, the dorsum of the tongue gave the highest yield of P. aeruginosa (27 strains), followed by the buccal mucosa (17 strains), saliva (15 strains), and dental plaques (6 strains). Eleven patients had P. aeruginosa in the oral cavity and sputum simultaneously. Antibiotic susceptibility tests on these multiple isolates suggest that CF patients may be cocolonized or coinfected by two or more strains of P. aeruginosa. Therefore, it may be important to identify multiple isolates of P. aeruginosa, not only from sputum cultures but also from oral cultures, for antibiotic-susceptibility testing. Oral colonization by the mucoid variants of P. aeruginosa may lead to further colonization in the lower respiratory tract and subsequent pulmonary infection in CF patients.

Adolescent↗
PubMed1985

Structures of trienomycins A, B and C, novel cytocidal ansamycin antibiotics.

The structures of novel antibiotics, trienomycins A, B and C produced by Streptomyces sp. No. 83-16, have been determined on the basis of their spectroscopical and chemical properties. Trienomycins are unique ansamycin antibiotics with a triene and an 1,3,5-trisubstituted benzene moieties in the molecule. The antibiotics possess potent cytocidal activity against HeLa S3 cells at concentrations of 0.005 (trienomycin A), 0.1 (trienomycin C) and 0.2 micrograms/ml (trienomycin B) (IC50 value), respectively. However, trienomycins showed no antimicrobial activity against the bacteria, fungi and yeasts examined with the exception of weak activity versus Piricularia oryzae at a concentration of 1,000 micrograms/ml.

Alanine↗
PubMed1985

Structural study of a new antitumor antibiotic, kazusamycin.

The structure of a new antitumor antibiotic, kazusamycin produced by Streptomyces sp. No. 81-484, was determined on the basis of its spectral and chemical properties. Kazusamycin has a structure characteristic of an unsaturated, branched-chain fatty acid with a terminal delta-lactone ring.

Antibiotics, Antineoplastic↗
PubMed1985

Antitumor activity of a new antibiotic, kazusamycin.

The antitumor activity of a new antibiotic, kazusamycin, against various murine tumors was studied by various treatment schedules. Single, intermittent, and successive injections of the antibiotic were almost equally effective against Ehrlich carcinoma, IMC carcinoma and sarcoma 180 tumor, but successive injections showed more efficacy than the other schedules against Meth A fibrosarcoma and Lewis lung carcinoma. Interestingly, there was no clear dose response for the efficacy of kazusamycin on murine tumors. When HeLa cells were exposed to kazusamycin for 72 hours in vitro, the IC50 value was about 1 ng/ml, however the cytotoxicity of the antibiotic depended on the incubation time.

Animals↗
PubMed1985

Studies on a novel cytocidal antibiotic, trienomycin A. Taxonomy, fermentation, isolation, and physico-chemical and biological characteristics.

A new antibiotic, trienomycin A, has been isolated from the culture broth of Streptomyces sp. No. 83-16. The physico-chemical characteristics of the antibiotic suggested that it belongs to the group of ansamycin antibiotics with a triene moiety in the molecule. The molecular formula of trienomycin A is C36H50N2O7 (MW 622). The antibiotic possesses potent cytocidal activity against HeLa S3 and PLC hepatoma cells at concentrations of 0.1 and 0.01 micrograms/ml (IC50 value) respectively. However, trienomycin A showed no antimicrobial activity against the bacteria, fungi and yeasts examined with the exception of weak activity versus Piricularia oryzae at a concentration of 1,000 micrograms/ml.

Alanine↗
PubMed1985

A novel antibiotic, sohbumycin. Taxonomy, fermentation, isolation and physico-chemical and biological characteristics.

A new antibiotic sohbumycin, was isolated from the culture broth of Streptomyces sp. No. 82-85. It appeared to belong to the peptide lactone type of antibiotics from physico-chemical studies and has an empirical formula of C31H47N8O10Cl. In in vitro studies, the antibiotic was found to possess potent cytocidal activity against HeLa S3 cells and antimicrobial activities against Gram-positive bacteria with MIC values about 0.3-0.6 microgram/ml, but showed no activity on the Gram-negative bacteria, yeast and fungi tested.

Anti-Bacterial Agents↗
PubMed1984

Antitumor activity of a nitrosourea derivative, CNUA, on murine tumors.

The antitumor activity of a new derivative of nitrosourea, 3-[3-(2-chloroethyl)-3-nitrosoureido]-3-deoxy-D-allose (CNUA), against murine tumors was studied. CNUA showed significant antitumor activity against L1210 leukemia, Lewis lung carcinoma, B-16 melanoma and autochthonous lung tumor induced by 1-ethyl-1-nitrosourea. The effect of CNUA, chlorozotocin, and ACNU on the peripheral white blood cell count (WBC) in normal CDF1 mice was examined. The lowest WBC count occurred 3 days after administration at the therapeutic dose level and the decreased value returned to the normal level 7-14 days following administration of CNUA and chlorozotocin. CNUA also exerted a depressive action on both humoral and cell-mediated immune response to sheep red blood cells determined by the serum hemagglutinin titer, plaque-forming cells in the spleen, and delayed-type hypersensitivity reaction, while the suppression was almost the same or less than that obtained with chlorozotocin when compared at the dose resulting in similar antitumor activity. These findings suggest that the antitumor activity of CNUA was not at all inferior to those of other nitrosoureas. The bone marrow toxicity was moderate and did not last long.

Animals↗
PubMed1984

Interbacterial adherence between Actinomyces viscosus and strains of Streptococcus pyogenes, Streptococcus agalactiae, and Pseudomonas aeruginosa.

Interbacterial adherence was sought between strains of Actinomyces viscosus indigenous to the human mouth and strains of Streptococcus pyogenes, Streptococcus agalactiae, and Pseudomonas aeruginosa. Six of nine strains of S. pyogenes, three of five strains of S. agalactiae, and two of four strains of P. aeruginosa were found to coaggregate with each of five strains of A. viscosus tested. Some coaggregation reactions were inhibited by 0.05 M lactose and were dependent upon heat- and protease-sensitive Actinomyces components. Such reactions appear to involve the galactosyl-binding adhesin previously described in type 2 fimbriae on A. viscosus. Other coaggregation reactions were dependent upon heat- and protease-sensitive components of the pathogen. That such pathogen strains possessed an adhesin(s) was further suggested by the observation that they agglutinated human erythrocytes. The ability of coaggregation-positive and -negative strains of S. pyogenes and S. agalactiae to adhere to Actinomyces-coated agarose beads was also studied. Coaggregation-positive streptococcal strains attached in higher numbers to the Actinomyces-coated beads than did strains which were coaggregation negative. Lactose (0.05 M) inhibited the attachment of those streptococcal strains which coaggregated with A. viscosus in a lactose-sensitive manner. The adherence of those streptococcal strains whose coaggregation appeared to depend upon the galactosyl-binding adhesin of A. viscosus was also reduced by components of human saliva. Crude sonic extracts of coaggregation-positive streptococci or of P. aeruginosa were also effective in aggregating Actinomyces cells. The effect of lactose and of salivary components on this extract-induced aggregation of Actinomyces cells generally paralleled that observed in other assays. The apparent prevalence and diversity of adherent reactions between the pathogens studied and indigenous strains of A. viscosus suggest that some may affect host susceptibility to these infectious agents.

Actinomyces↗
PubMed1984

A new antitumor antibiotic, kazusamycin.

A new antibiotic kazusamycin, was isolated from the culture broth of Streptomyces sp. No. 81-484, which shows antitumor activity against experimental murine tumors. This antibiotic did not possess antibacterial activity against Gram-positive and Gram-negative bacteria, but showed strong cytotoxic activity against HeLa cells in vitro. The chemical and physico-chemical properties of kazusamycin suggest that the molecular formula of this antibiotic is C33H48O7 (MW 556).

Animals↗