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Biomedical subjects

M Tsuboi

Publications and source records attributed to M Tsuboi.

At least 181 records · Page 10Linked to original sources
PubMed1985

Increased stability of the higher order structure of chicken erythrocyte chromatin: nanosecond anisotropy studies of intercalated ethidium.

Internal motion of the DNA in chicken erythrocyte chromatin fibers was studied by measurement of the fluorescence anisotropy decay of ethidium intercalated in the linker region. A comparison of the decay curves of the dye in chicken erythrocyte chromatin with those of calf thymus chromatin [Ashikawa, I., Kinosita, K., Jr., Ikegami, A., Nishimura, Y., Tsuboi, M., Watanabe, K., Iso, K., & Nakano, T. (1983) Biochemistry 22, 6018-6026] revealed greater suppression of nucleosome movement in chicken erythrocyte chromatin. Furthermore, the transition of this chromatin to the compact (solenoidal) structure occurred at lower solvent concentrations of Na+ or Mg2+ than those for calf thymus chromatin. These results demonstrated increased stability of the higher order structure (the solenoid) of chicken erythrocyte chromatin, which may be related to the reduction of nuclear activity in the chicken erythrocyte cell. In addition to intact chicken erythrocyte chromatin, we studied the structural transitions of H1-depleted and H1,H5-depleted chromatins. The result indicated that histone H5 of this chromatin stabilizes the higher order structure in the presence of magnesium (or divalent) cation and did not induce the transition in the solution containing only sodium cation.

Animals↗
PubMed1985

The resonance Raman frequencies of the Fe-CO stretching and bending modes in the CO complex of cytochrome P-450cam.

Resonance Raman spectra of the ferrous CO complex of cytochrome P-450cam have been observed both in its camphor-bound and free states. Upon excitation at 457.9 nm, near the absorption maximum of the Soret band, the ferrous CO complex of the camphor-bound enzyme showed an anomalously intense Raman line at 481 cm-1 besides the strong Raman lines at 1366 and 674 cm-1 for the porphyrin vibrations. The Raman line at 481 cm-1 (of the 12C16O complex) shifted to 478 cm-1 upon the substitution by 13C16O and to 473 cm-1 by 12C18O without any detectable shift in porphyrin Raman lines. This shows that the line at 481 cm-1 is assignable to Fe-CO stretching vibration. By the excitation at 457.9 nm, a weak Raman line was also observed at 558 cm-1, which was assigned to the Fe-C-O bending vibration, because it was found to shift by -14 cm-1 on 13C16O substitution while only -3 cm-1 on 12C18O substitution. These stretching and bending vibrations of the Fe-CO bond were not detected with the excitation at 413.1 nm, though the porphyrin Raman lines at 1366 and 674 cm-1 were clearly observed. When the substrate, camphor, was removed from the enzyme, the Fe-CO stretching vibration was found to shift to 464 cm-1 from 481 cm-1, while no detectable changes were found in porphyrin Raman lines. This means that the bound substrate interacts predominantly with the Fe-CO portion of the enzyme molecule.

Camphor↗
PubMed1985

Cloning and mapping of the sporulation gene, spoT7, in Saccharomyces cerevisiae.

In order to isolate a DNA fragment able to complement a sporulation-deficient mutation in Saccharomyces cerevisiae, a simple screening procedure was devised which was based on the difference in osmotic sensitivity between protoplasts and spores. A plasmid (pHT7) containing a 13 kb DNA insert that complemented the spoT7 mutation was isolated from a yeast genomic library prepared in the vector YEp13. Gene spoT7 was linked to rna1 at 1.2 cM and to mak27 at 7.2 cM on the right arm of chromosome XIII. Mapping of the cloned gene following integration into the chromosome showed that the cloned gene was allelic to spoT7 and that a part of the RNA1 gene was also cloned into the same fragment. Gene spoT7 was localized on a 5 kb DNA fragment by further subcloning.

Chromosome Mapping↗
PubMed1985

Hexose and hexosamine concentrations in human pancreatic juice.

Hexose and hexosamine contents were measured in 117 samples of either duodenal or pancreatic juice from 49 subjects. The specimens were obtained by three methods: firstly, through a Dreiling's double lumen tube and with a pancreozymin secretin test performed simultaneously; secondly, by fiber duodenoscopy after an intravenous injection of secretin; thirdly, through a postoperative cannula without stimulation. The hexose content measured by phenol-sulfuric acid reaction correlated well with the hexosamine content measured by the Elson-Morgan method (r = 0.63, p less than 0.005). Since determination of hexose is not as complicated as that of hexosamine, the measurement of hexose content in the pancreatic juice seems to be more useful than measuring hexosamine for obtaining valuable information on pancreatic abnormalities.

Cholecystokinin↗
PubMed1985

Glossopharyngeal neuralgia with cardiac syncope. A case successfully treated by microvascular decompression.

A case of glossopharyngeal neuralgia associated with episodic cardiac arrest and syncope is presented. Posterior fossa exploration showed that the left glossopharyngeal and vagus nerves were compressed by the posterior inferior cerebellar artery. Microvascular decompression resulted in complete relief of glossopharyngeal neuralgia, cardiac syncope, and seizure. The mechanism of glossopharyngeal neuralgia associated with cardiac syncope is discussed.

Adult↗
PubMed1985

Deuteration kinetics of deoxyguanosine, deoxycytidine, and their polynucleotides by means of ultraviolet spectrophotometry.

The kinetics of the hydrogen-deuterium exchange reactions of deoxyguanosine (dG), deoxycytidine (dC), double-helical poly[d(G-C)] X poly[d(G-C], and double-helical poly(dG) X poly(dC) have been examined at 20 degrees C, pH 7.0, and in low-salt (0.15 M NaCl) medium by stopped-flow ultraviolet spectrophotometry, in the spectral region of 260 to 320 nm. The rate constant was found to be 78.9 s-1 for dG-NH, 2.2 s-1 for dG-NH2, 39.3 s-1 for dC-NH2, 2.4 s-1 (fast) and 0.94 s-1 (slow) for poly[d(G-C)] X poly[d(G-C)], and 2.2 s-1 (fast) and 0.92 s-1 (slow) for poly(dG) X poly(dC). From these values, the probability of base-pair opening of the G X C containing B-form double helix is estimated to be (3 +/- 1) X 10(-3). This is much greater than what is expected from an extrapolation of the van't Hoff plot at the helix-coil transition region, i.e. at about 110 degrees C. The mechanism of these base-pair openings at 20 degrees C (as well as the mechanism of base-pair reformation) is suggested to be totally different from those in the melting temperature range.

Base Composition↗
PubMed1985

Determination of pipemidic acid in plasma by normal-phase high-pressure liquid chromatography.

An improved high-pressure liquid chromatography procedure for determining the concentration of pipemidic acid in human plasma was developed, which uses a normal-phase silica gel column and aqueous mobile solvent system similar to that used in reverse-phase chromatography. Precolumn derivatization of pipemidic acid was achieved by a methylation reaction with boron trifluoride in methanol after extraction from plasma with chloroform containing 4% ethanol. The percent recovery of pipemidic acid was 88.3 +/- 7.7, the variation of which became negligible when quinacrine was used as an internal standard for the determination. High-pressure liquid chromatography analysis was performed by conventional silica gel and mobile solvent mixtures containing 3% of 0.14% HClO4 solution, 19% methanol, and 78% chloroform. The UV detector was set at 265 nm. The detection limit of pipemidic acid methyl ester was as low as 10 ng of the injection amounts or 0.5 micrograms of the plasma per ml, with 0.01 absorbance units (full scale) and a signal-to-noise ratio of 3.

Adult↗
PubMed1985

C56 formation in the reaction mixture of isolated complement components through the classical complement pathway.

The mechanism of hemolysis of unsensitized erythrocytes by a mixture of 9 isolated, human-derived complement components, C1s, C4, C2, C3, C5, C6, C7, C8 and C9 (C1s-C9) was studied. Of the tested erythrocytes, guinea pig erythrocytes (Egp) were the most susceptible to lysis by C1s-C9, followed by human and sheep erythrocytes. Contamination of the isolated complement components by C56 was ruled out. It was determined that a factor was generated in the reaction mixture of C1s, C4, C2, C3, C5 and C6 (C1s-C6), which had lytic activity against Egp when C7, C8 and C9 were added. We found that the lytic factor was similar to C56 in the following properties: (1) the activity of the lytic factor decreased when incubated with isolated C7 prior to its reaction with Egp; (2) the lytic factor did not bind to Egp by itself but it did bind in the presence of C7; (3) EDTA did not have any inhibitory effect on the lytic factor; (4) the activity of the lytic factor decreased by treatment with anti-C5 and anti-C6 but not by treatment with anti-C3 and anti-C4, and (5) gel filtration of the reaction mixture (C1s-C6) indicated that the elution volumes of the lytic factor and of isolated C56 were similar. Thus, it is likely that C56 is generated in the reaction mixture of C1s-C6 and the lytic factor binds to unsensitized erythrocytes together with C7, to form an intermediate EC567 which is susceptible to lysis by the action of C8 and C9.

Animals↗
PubMed1985

Sex difference in the effect of aspirin on rat platelet aggregation and arachidonic acid metabolism.

The rat platelet aggregation induced by collagen was stronger in males than in females. The platelet malondialdehyde (MDA) production was more in males than in females, and the platelet cyclooxygenase activity was higher in males than in females. Aspirin at a dose of 10 mg/kg inhibited the collagen-induced aggregation in males, but not in females. Aspirin at a dose of 5 mg/kg blocked the MDA production only in males, but aspirin at a dose of 10 mg/kg inhibited the MDA production in both sexes. The effect of aspirin on the cyclooxygenase activity was only in males, but aspirin at a dose of 10 mg/kg inhibited the MDA production in both sexes. The effect of aspirin on the cyclooxygenase activity was similar to that on the MDA production. In gonadectomized rats, the MDA production and the cyclooxygenase activity were decreased by castration, and they were increased by ovariectomy. Aspirin at a dose of 5 mg/kg failed to inhibit them in castrated rats. Besides, in in vitro experiments, aspirin also inhibited the MDA production and the aggregation. Nevertheless, there was no sex difference in the content of arachidonic acid, a substrate of platelet cyclooxygenase. It is suggested that there is a sex difference in rat platelet cyclooxygenase activity, and it is closely related to the sex difference in the antiplatelet effect of aspirin.

Animals↗
PubMed1985

Isolation and characterization of hemorrhagic toxin g from the venom of Crotalus atrox (western diamondback rattlesnake).

Hemorrhagic toxin g (HT-g) was isolated from Crotalus atrox (western diamondback rattlesnake) venom using a five-step purification procedure to obtain approximately equal to 5.9 mg of purified HT-g from 2.0 g of crude venom. The purified toxin was homogeneous by disc electrophoresis on polyacrylamide gel at pH 8.3 and 4.3, and by isoelectric focusing. HT-g possessed lethal, hemorrhagic and proteolytic activities. These activities of toxin were inhibited by ethylenediamine-tetraacetic acid (EDTA), 1,10-phenanthroline or ethyleneglycol (beta-amino-ethyl) N,N,N',N'-tetracetic acid (EGTA), but not by cysteine or soybean trypsin inhibitor (SBTI). Its molecular weight was approximately 60,000 and the isoelectric point was 6.8. The toxin contains 516 amino acid residues. HT-g did not coagulate fibrinogen to fibrin; however, the toxin hydrolysed the A alpha-chain or B beta-chain of fibrinogen without cleaving the gamma-chain. HT-g produced only local hemorrhage in internal organs such as the intestine, heart and liver.

Amino Acids↗
PubMed1985

[Studies on the relationship between the oxygen uptake and the release of amylase and sialic acid].

The relationship between the oxygen uptake and the release of amylase and sialic acid induced by pilocarpine was investigated in dog submandibular glands. Pilocarpine dose-dependently stimulated the oxygen uptake. The dose required for the maximal response was 10 microM. The release of amylase and sialic acid induced by pilocarpine was inhibited by the addition of iodoacetic acid, malonic acid, 2, 4-dinitrophenol, antimycin A or sodium azide. The oxygen uptake induced by pilocarpine was significantly inhibited by iodoacetic acid, malonic acid, antimycin A or sodium azide. On the other hand, 2, 4-dinitrophenol further stimulated the oxygen uptake by pilocarpine. The increase in the oxygen uptake or the release of amylase and sialic acid induced by pilocarpine was significantly inhibited by ouabain. The Na+, K+-ATPase activity ratio in the microsomal fraction of dog submandibular glands was dose-dependently increased by pilocarpine. The Na+, K+-ATPase activity ratio induced by pilocarpine was significantly inhibited by ouabain, antimycin A, oligomycin or 2, 4-dinitrophenol. The pilocarpine-induced Na+, K+-ATPase activity ratio was significantly inhibited by the removal Ca2+ from the medium or the addition of 2 mM EGTA. These results suggest that the increase in the oxygen uptake by pilocarpine is profoundly involved in the energy supply for the process of amylase and sialic acid release. In particular, the energy supply demanded for the activation of Na+ pump may play a role in the mechanism by which pilocarpine induces the oxygen uptake.

Amylases↗
PubMed1985

Salt induced conformational transition between A and Z forms of r(CGCGCG) as revealed by a Raman spectroscopic study.

Solution conformation in different conditions of r(CGCGCG) has been studied by a Raman spectroscopic method. In NaCl solution, r (CGCGCG) takes only an A-form duplex in which guanosine and cytidine have C3'endo-anti conformation even at 5M salt concentration. In much higher ionic strength condition (5M NaCl plus 1M MgCl2 or 6M NaClO4), it undergoes a transition to a left-handed Z-form. The Raman spectrum of the Z-form RNA was found to be very similar to that of Z-form DNA, suggesting that Z-RNA involves a C3'endo-syn guanosine and an in between form of C2'endo-Cl'exo-anti cytidine.

Kinetics↗
PubMed1984

Structure-spectrum correlations in nucleic acids. I. Raman lines in the 600-700 cm-1 range of guanosine residue.

Raman spectra of nine crystals of known structures which involve guanosine moieties with various conformations have been observed. It has been established that a guanosine residue with the C3'endo-anti conformation gives a strong Raman line at 666 +/- 2 cm-1. It has also been found that the residue with 04'endo-anti gives a strong Raman line at 682 cm-1, and C3'exo-syn at 616 cm-1. The usefulness of these structure-spectrum correlations in the conformation studies of polynucleotides are shown.

Base Sequence↗
PubMed1984

Rotational dynamics of immunoglobulins with fluorescent haptens on a membrane surface.

The rotational dynamics of rabbit immunoglobulin G with fluorescent lipid haptens on a membrane surface has been studied by nanosecond fluorescence emission anisotropic spectroscopy. It has been found that the rotational angles of the antibody are very restricted on the membrane, but that the rotation rate itself is not appreciably lower than that in solution, and is independent of the membrane fluidity.

Animals↗
PubMed1984

A hydrogen exchange study of the open segment in a DNA double helix.

The kinetics of the hydrogen-deuterium exchange reactions of double-helical poly[d(A-T)] X poly[d(A-T)], poly(dA) X poly(dT), and constituent nucleosides (deoxyadenosine and thymidine) have been examined at various temperatures by stopped-flow ultraviolet spectrophotometry, in the spectral region 240-300 nm. The results were interpreted on the basis of a mechanism of the hydrogen exchange reaction of a helical polynucleotide, proposed by Englander and colleagues as well as by the Tsuboi and Nakanishi group. It was concluded that the rates of the base-pair opening reactions are nearly equal to one another in double-helical DNAs, irrespective of the base sequence. On the other hand, the free energy required for bringing the open segment at a particular base-pair was found to be much greater for poly(dA) X poly(dT) than for poly[d(A-T)] X poly[d(A-T)].

DNA↗