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Biomedical subjects

Y Usami

Publications and source records attributed to Y Usami.

50 records · Page 3Linked to original sources
PubMed1989

Pseudomonas aeruginosa cytotoxin: the nucleotide sequence of the gene and the mechanism of activation of the protoxin.

The gene encoding cytotoxin (ctx) was cloned from Pseudomonas aeruginosa 158 and the nucleotide sequence was determined. The structural gene of ctx encodes the procytotoxin of 286 amino acid residues with a molecular mass of 31,681 Daltons. Procytotoxin was activated by removal of 20 amino acid residues from the C terminus with trypsin. The cloned ctx gene was not expressed in either an Escherichia coli strain or a cytotoxin non-producing strain of P. aeruginosa. An expression system for the ctx gene was constructed by placing the structural gene of ctx downstream of tac promoter on a broad host-range vector plasmid.

Amino Acid Sequence↗
PubMed1988

An enzyme immunoassay for cuprozinc superoxide dismutase using monoclonal antibodies. Application for pharmacokinetic study.

We developed an enzyme immunoassay for determining human cuprozinc superoxide dismutase (h-SOD) using two kinds of monoclonal antibodies prepared by immunizing h-SOD to BALB/c mice. This method was sensitive and specific enough to determine exogenous h-SOD injected into rats. When intravenously injected into rats, much of the immunoreactive h-SOD accumulated in the kidney and was rapidly excreted in the urine. We observed both a modified and an unmodified form of exogenous h-SOD in rat urine.

Animals↗
PubMed1988

Augmentation rhinoplasty.

Augmentation rhinoplasty using a silicone implant is the most popular operation in Japan, but is not without several complications such as exposure of the implant and its deviation. We obtained good results in preventing these complications by a fixation at the hollow which is made by chiseling the frontal bone and by fibrous tissue which grows through the small holes of the implant tail.

Cleft Lip↗
PubMed1987

[Futraful and UFT, their metabolic characteristics].

Investigations were made in human on the metabolism of Futraful (FT) and UFT (combination of uracil and FT), both of which are anticancer agents of pyrimidine metabolism antagonist. As a result, it was demonstrated that from the metabolic view point, those drugs essentially have a tumor-selective toxicity. Next, the mechanism of the superior clinical anticancer effect of UFT, compared to FT, was investigated enzymatically, showing the inhibitory effect of uracil on the degradation of 5-fluorouracil generated from FT in the organs and tumor tissues. Discussions were also made for the further development of fluoropyrimidines.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1980

Inhibition of tyrosinase activity by 4-tert-butylcatechol and other depigmenting agents.

4-tert-Butylcatechol (TBC) is an antioxidant widely used in industry and a potent depigmenting agent to the skin of the workers. In this study, tyrosinase was extracted from tissue-cultured human melanoma cells and purified by polyacrylamide gel electrophoresis. T1 and T2 tyrosinase, which migrated differently on the gels, were treated with TBC as well as other depigmenting agents and natural substrates of tyrosinase. Changes in the enzyme activity on dopa oxidation were quantified by photometric and radiometric analysis. The enzyme activity was inhibited by TBC and hydroquinone, but only at a high concentration that is toxic to tissue-cultured melanocytes. The activity was also decreased by tyrosine, but was increased by dopa, particularly at a lower concentration. The results indicated that the reported methodology is useful for testing the effects of chemicals with depigmenting or pigmenting potential. TBC and hydroquinone are inhibitors of tyrosinase at concentrations higher than 1 x 10(-3) M. Dopa and tyrosine alter tyrosinase activity in the second step of melanogenesis in the same manner that has been reported to occur in the first step-conversion of tyrosine to dopa.

Antioxidants↗
PubMedDate not supplied

Detection of antibodies to avian pneumovirus by a micro-indirect immunofluorescent antibody test.

A micro-indirect immunofluorescent antibody (micro-IFA) test with a 96-well, flat-bottomed microplate was developed for measuring avian pneumovirus (APV) antibodies. Two Japanese APV strains (MM-1, 8597/CV94) isolated at different places and times and Vero cells were used for antigen preparation in this test. The test results were compared with those of a serum neutralization (SN) test. By the micro-IFA test, specific immunofluorescent antigens were observed in the cytoplasm of cells infected with either strain, and the antibody titers of antisera to these strains were quite similar. In most cases, the results were obtained within 3 hr. Antibody titers between the micro-IFA and SN tests were highly correlated, with correlation coefficients of 0.873 (MM-1 strain) and 0.889 (8597/CV94 strain). We also investigated APV antibody status in two farms for a period of about 2 yr by the micro-IFA test and revealed that APV infections were repeated within these farms. On the basis of these results, we conclude that our micro-IFA test is useful for routine serologic surveys of APV infections, particularly when a large number of samples are to be treated, because this test was time and labor saving relative to SN tests or conventional IFA tests utilizing embryo tracheal organs or coverslip cell cultures.

Animals↗