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Biomedical subjects

Y Mitsui

Publications and source records attributed to Y Mitsui.

At least 289 records · Page 16Linked to original sources
PubMed1985

Actions of exogenous heparan sulfate and hyaluronic acid on growth and thymidine incorporation of normal and transformed human fibroblasts. A comparison with the effects of high cell density and low serum concentration and a warning against thymidine incorporation as a measure of DNA synthesis.

Treatment of normal human (WI-38) cells with exogenous heparan sulfate (HS) reduced cell growth and incorporation of radio-isotope-labeled thymidine (TdR) into DNA. In spite that growth of their transformants (WI-38 CT-1) was enhanced by HS treatment, transformed cells also decreased in TdR incorporation thereby. This peculiar observation was explained by a reduction of TdR uptake, leading to a decrease in specific radioactivity of newly synthesized DNA. The changes in cell growth and TdR incorporation by HS treatment were revealed to be similar to the changes with increasing cell density rather than by serum starvation.

Biological Transport↗
PubMed1985

Crystallization of calcium-calmodulin-trifluoperazine complex and an attempt at crystallizing calcium-free calmodulin.

Crystals suitable for X-ray structure analysis were obtained for CaM complexed with both calcium ions and a phenothiazine drug, trifluoperazine (TFP). The TFP/CaM binding ratio in crystals was experimentally determined to be nearly 1. An attempt at crystallizing calcium-free calmodulin (CaM) resulted in rigid but non-birefringent solids which exhibited no X-ray reflections.

Animals↗
PubMed1985

Interactions of Streptomyces subtilisin inhibitor with Streptomyces griseus proteases A and B. Enzyme kinetic and computer simulation studies.

Streptomyces subtilisin inhibitor (SSI), a dimeric protein that strongly inhibits subtilisins, was shown to form tight inhibitory complexes with Streptomyces griseus proteases A and B (SGPA and SGPB). The apparent dissociation constants of the SGPA-SSI and SGPB-SSI complexes were found to be orders of magnitude less than those of subtilisin-SSI complexes. Using the known atomic coordinates for SGPA and SSI, the highly complementary nature of the surface geometries of the two proteins was confirmed by a computer graphics study, which led to a proposed structure for the SGPA-SSI complex. Kinetic studies further suggested that the SSI dimer can bind two molecules of either SGPA or SGPB, and the 2:1-complexes (consisting of one inhibitor dimer and one enzyme molecule) apparently possess lower intrinsic dissociation constants than the 2:2-complexes. It was also shown that both of SGPA and SGPB are inhibited by both soybean trypsin inhibitor (Kunitz) and bovine pancreatic trypsin inhibitor (Kunitz), but far less strongly than by SSI.

Aspartic Acid Endopeptidases↗
PubMed1985

[Study on the transfer of cefminox into female genital organs].

One gram of cefminox (CMNX, MT-141) was injected intravenously to a total of 29 patients prior to abdominal total hysterectomy and drug levels in the uterine and adnexal tissues were bioassayed. Serum samples and uterine tissues were taken at 0.25, 0.5, 1, 2, 4 or 6 hours after the administration, when bilateral uterine arteries were clamped. As to serum levels no difference has seen between cubital venous serum and uterine arterial serum, the half-lives being 2.32 hours and 2.22 hours, respectively. The peak level was 66.7 micrograms/ml for both. The drug level in tissues reached its peak at 15 minutes in the myometrium and cervix uteri, at 30 minutes in the endometrium, portio vaginalis and oviduct and at 1 hour in the ovary. The mean peak level was the highest for the oviduct (55.3 micrograms/g), followed by the portio vaginalis (47.7 micrograms/g), the cervix uteri (46.2 micrograms/g), the myometrium (42.8 micrograms/g), the ovary (37.3 micrograms/g) and the endometrium (34.2 micrograms/g) in this order. After reached the highest levels, the tissue levels decreased gradually in the same manner as the serum levels. From these results it was shown that CMNX is well transferred into various female genital tissues to achieve concentrations higher than MICs for organisms isolated clinically with high incidences in the field of gynecology and obstetrics. It was assumed from these results that CMNX is clinically useful enough in the treatment of genital organ infections.

Adult↗
PubMed1984

Crystal structure at 2.6 A resolution of the complex of subtilisin BPN' with streptomyces subtilisin inhibitor.

The crystal structure of the complex of a bacterial alkaline serine proteinase, subtilisin BPN', with its proteinaceous inhibitor SSI (Streptomyces subtilisin inhibitor) was solved at 2.6 A resolution. Compared with other similar complexes involving serine proteinases of the trypsin family, the present structure is unique in several respects. (1) In addition to the usual antiparallel beta-sheet involving the P1, P2 and P3 residues of the inhibitor, the P4, P5 and P6 residues form an antiparallel beta-sheet with a previously unnoticed chain segment (residues 102 through 104, which was named the S4-6 site) of subtilisin BPN'. (2) The S4-6 site does not exist in serine proteinases of the trypsin family, whether of mammalian or microbial origin. (3) Global induced-fit movement seems to occur on SSI: a channel-like structure in SSI where hydrophobic side-chains are sandwiched between two lobes becomes about 2 A wider upon complexing with subtilisin. (4) The complex is most probably a Michaelis complex, as in most of the other complexes. (5) The main role of the "secondary contact region" of SSI seems to be to support the reactive site loop ("primary contact region"). Steric homology of the two contact regions between the inhibitors of the SSI family and the pancreatic secretory trypsin inhibitor-ovomucoid inhibitor family is so high that it seems to indicate divergent evolutionary processes and to support the general notion as to the relationship of prokaryotic and eukaryotic genes put forward by Doolittle (1978).

Amino Acid Sequence↗
PubMed1984

Heparan sulfate enhances growth of transformed human cells.

Previous studies showed that cell surface heparan sulfate (HS) is involved in density-dependent growth regulation of normal human cells. In this study the effects of HS on proliferation of transformed cells were studied in vitro. Exogenously added HS prepared from normal tissues (rat kidney and bovine kidney) enhanced growth of transformed human and animal cells (gamma ray- or virus-transformed WI-38, and HeLa cells and chemically induced mouse hepatoma cells), but inhibited that of normal human and animal cells (WI-38, 3T3, and rabbit liver cells). HS was less effective on growth of both normal and transformed human cells at higher cell density. Although the exogenous HS did not bind to cells tightly, HS was found to affect cell growth not by modulation of growth-related substances in the medium, but through contact with the cell surface. HS preparation from tumour cells (mouse hepatoma cells) exerted similar effects on cell growth. Heparin, structurally similar to HS, inhibited growth of both normal and transformed human cells. These findings suggest that: 1. HS plays a particular function in contact regulation of cell proliferation. 2. Transformation-related changes in the structure of HS molecules do not much affect the function of HS. 3. The cellular transformation, however, is accompanied by alteration in the growth-regulating system sensitive to extracellular HS.

Animals↗
PubMed1984

[Study on transfer of ceftriaxone into female genital organs].

One gram of ceftriaxone (Ro 13-9904, CTRX), a new cephalosporin antibiotic, was given intravenously to a total of 25 patients prior to abdominal total hysterectomy for uterine myoma with or without small benign ovarian tumor. Bilateral uterine arteries were clamped at 0.5, 1, 2, 6, 12 and 24 hours after administration, and serum samples and uterine tissues were taken for the measurement of CTRX concentration by bioassay method. A little difference was found in the serum concentration between cubital venous and uterine arterial serum, the half-lives being 8.0 and 7.9 hours, respectively. The initial concentrations were estimated to be 153 micrograms/ml and 160 micrograms/ml, respectively. The tissue peak concentrations were obtained at 30 minutes in the myometrium, portio vaginalis, oviduct and ovary, and at 1 hour in the endometrium and cervix uteri. These were 41, 51, 51, 39, 42 and 47 micrograms/g, respectively. The tissue concentrations after peak decreased in the same manner as the serum concentrations. Judging from its favorable transfer into the uterine tissues, CTRX was evaluated to be clinically useful in the treatment of obstetrical and gynecological infections.

Cefotaxime↗
PubMed1983

Reinitiation of host DNA synthesis in senescent human diploid cells by infection with Simian virus 40.

Human diploid fibroblasts, TIG-1, cease to proliferate at about 60-62 population doubling level. In their senescent state used in this study, the percentage of nuclei labeled by [3H]thymidine for 48 h was around 1-2% in fresh medium containing 5-40% fetal bovine serum. The percentage of labelled nuclei increased up to 10-fold after infection with SV40. This increase reflects stimulation of cell DNA synthesis because: 1. The increase also occurred when ts A900 was used for infection at the non-permissive temperature, under these conditions viral DNA synthesis is inhibited; 2, the increase paralleled the stimulation of [3H]thymidine incorporation into DNA in a Hirt-precipitate fraction from SV40-infected cells. UV-irradiated SV40 had reduced ability to induce DNA synthesis. A viable deletion mutant of SV40, d1940, had almost the same activity to induce cell DNA synthesis as did wild-type SV40. Equilibrium density gradient centrifugation analysis of DNA labelled with 5-bromodeoxyuridine (BrdU) supported semiconservative replication rather than repair synthesis. We conclude that a considerable fraction of human diploid cells in a senescent population initiate host DNA replication by infection with SV40, although these cells cannot be stimulated with fetal bovine serum.

Antigens, Viral↗
PubMed1983

Preliminary chemical and X-ray studies on the interactions of E. coli DNA with putrescine.

The interactions of putrescine, the major diamine in E. coli, with E. coli DNA as a model of phage DNA were studied by melting temperature analysis, equilibrium dialysis and X-ray diffraction with the aid of molecular model building. The chemical analysis of the DNA-putrescine complex shows that the molar binding ratio of putrescine to DNA (phosphate) is nearly 1 to 2. The equilibrium (or reversible) binding of putrescine to DNA was suggested by the fact that the melting temperature increased according to the concentration of added putrescine, and its elevation was not saturated even at the molar ratio of 6 to 1. The equilibrium dialysis experiments indicate that the association constant for the complex is a little smaller than, but in the same order (10(3) liter/mol) as, that of DNA-spermine complex. The binding of putrescine stabilizes the B-form of DNA fiber, which is well preserved even at 66% relative humidity. The distance between the neighboring DNA helices in the wet fiber increased with the increasing degree of hydration, as in the case of native DNA. Unlike spermine, putrescine does not form precipitate upon mixing with DNA in the concentration range for UV measurement, suggesting that the cross-bridge formed by putrescine is intra-double helical. The equilibrium binding of putrescine to DNA, seems to be important for the life cycle of lambda-phage.

Chemical Phenomena↗
PubMed1983

Cultured rabbit gastric epithelial cells producing prostaglandin I2.

A new method with Dispase, a bacterial neutral protease, was developed for purification of gastric mucosal cells from rabbit fetuses. These cells formed a typical polygonal monolayer after removal of fibroblastlike cells by Dispase treatment, and preserved the features of "normal" cells, exhibiting in vitro aging with a finite life span. The culture consisted mainly of surface mucous cells (50%-60% of the total cell population) and produced prostaglandins (predominantly I2). The addition of acetylsalicylic acid to the culture medium caused marked inhibition of prostaglandin production by the cultured gastric epithelial cells. This epithelial cell strain will be useful in studies on cytoprotection of the stomach.

Animals↗
PubMed1982

Effect of growth stage on histone H1 metabolism in human diploid fibroblasts.

Metabolism of histone H1 at different stages of cell growth was investigated in order to get a better understanding of the role of histone H1 in the cell growth of human diploid fibroblasts. Histone H1 content exhibited some fluctuation during the culture stage of cell growth. When cells entered confluent phase, the ratio of histone H1 to total histones decreased significantly. Histone H1 had a turnover half-life of 80 hours whereas nucleosomal histones did not significantly turn-over regardless of the growth stage. DNA synthesis was drastically diminished with increased cell density whereas histone synthesis was less sensitive to contact-inhibition. The gradual decline of histone H1 content with increased cell density suggests that its degradation is slightly superior to its residual synthesis. When the confluent cells were seeded at low density, cell proliferation resumed and histone H1 was synthesized and deposited to chromatin in a greater amount than nucleosomal histones, thus resulting in an abrupt increase of histone H1 content. The possible role of histone H1 metabolism in normal cells is discussed.

Cell Division↗