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Biomedical subjects

S Kanaya

Publications and source records attributed to S Kanaya.

At least 163 records · Page 9Linked to original sources
PubMed1991

Left ventricular function in patients with stable systemic lupus erythematosus.

Echocardiography was used to compare the left ventricular function of 43 female patients with stable systemic lupus erythematosus with 93 healthy females in 3 age groups. Left ventricular systolic function was evaluated by the left ventricular ejection fraction and left ventricular diastolic function was evaluated by the diastolic descent rate of the anterior mitral leaflet (DDR), the ratio of mean systolic velocity to mean diastolic velocity in the left ventricular posterior wall (D/S ratio) and the ratio of peak mitral inflow velocity during the atrial filling period to that in the early filling period (A/E ratio). The left ventricular ejection fraction was not significantly different between patients and normal subjects. However, left ventricular diastolic function evaluated by these indexes in patients was different from normal subjects. These data suggest that left ventricular diastolic function is lower in patients with stable systemic lupus erythematosus than in normal subjects. It appears to deteriorate progressively with age. However, left ventricular systolic function remains normal.

Adolescent↗
PubMed1991

Specificity of promoter consensus sequences in Escherichia coli chromosome.

Conservativeness of promoter-like sequences in transcribed and non-transcribed strands for polycistronic and monocistronic transcriptional units in Escherichia coli is investigated with chi 2-statistics. The results show that according with the degree of similarity to the consensus sequence (TTGACA--TATAAT), differences of frequencies with the theoretical one change from plus to minus.

Base Sequence↗
PubMed1990

Introduction of a non-native disulfide bridge to human lysozyme by cysteine scanning mutagenesis.

To examine whether the disulfide bridge between residues 65 and 81 can be replaced by a non-native disulfide bridge in the mutant h-lysozyme C77/95A and whether the formation of such a new disulfide bridge affects the folding of the protein, cysteine scanning mutagenesis has been performed within two discontinuous segments (residues 61-67 for the mutant C65/77/95A, and 74-84 for the mutant C77/81/95A). The position of the Cys residue at 65 or 81 was continuously shifted by site-directed mutagenesis. Of the mutants, only substitution of Cys for Trp64 allowed the secretion of mutant h-lysozyme(W64C) into the medium in a sufficient amount for analysis. After the purification, the mutant enzyme was obtained as two components (W64C-A and W64C-B). The only difference between A and B was that A had a peptide bond cleaved between Ala77 and His78. A non-native disulfide bridge between residues 64-81 was found in both components. Little difference was observed in CD spectra among wild-type and mutant enzymes. It is likely that the tertiary structure of the W64C mutant might be distorted at the location, because the directions of amino acid side chains at positions of 64 and 81 are shown to be opposite to each other in wild-type h-lysozyme by X-ray crystallographic analysis.

Amino Acid Sequence↗
PubMed1990

Role of cysteine residues in ribonuclease H from Escherichia coli. Site-directed mutagenesis and chemical modification.

The role of the three cysteine residues at positions 13, 63 and 133 in Escherichia coli RNAase H, an enzyme that is sensitive to N-ethylmaleimide [Berkower, Leis & Hurwitz (1973) J. Biol. Chem. 248, 5914-5921], was examined by using both site-directed mutagenesis and chemical modification. Novel aspects that were found are as follows. First, none of the cysteine residues is required for activity. Secondly, chemical modification of either Cys-13 or Cys-133 with thiol-blocking reagents inactivates the enzyme, but that of Cys-63 does not. Thus the sensitivity of E. coli RNAase H to N-ethylmaleimide arises not from blocking of the thiol group but from steric hindrance by the modifying group incorporated at either Cys-13 or Cys-133.

Amino Acid Sequence↗
PubMed1990

Three-dimensional structure of ribonuclease H from E. coli.

The three-dimensional structure of RNase H from Escherichia coli was determined at 1.8 A resolution by X-ray crystallography. The enzyme was found to belong to the alpha + beta class of structures, consisting of two distinct domains. The structure implies a possible region interacting with a DNA-RNA hybrid. The Mg2(+)-binding site essential for activity is located near a cluster of four acidic amino acids--one glutamic and three aspartic acid residues. These residues are completely conserved in the homology alignment of sequences of RNase H and reverse transcriptases from retroviruses and retrovirus-like entities. The structural motif of beta strands around the Mg2(+)-binding site has similarities to that in DNase I.

Amino Acid Sequence↗
PubMed1990

Identification of the amino acid residues involved in an active site of Escherichia coli ribonuclease H by site-directed mutagenesis.

The amino acid residues essential for the catalytic activity of ribonuclease H (RNase H) from Escherichia coli (E. coli) were identified by site-directed mutagenesis. It has been proposed by computer analysis that E. coli RNase H has homologous amino acid sequence with the RNase H domains of various retroviral reverse transcriptases (RTs) (Johnson, M. S., McClure, M. A., Feng, D. F., Gray, J., and Doolittle, R. F. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7648--7652). Of the eight highly conserved residues examined, Asp10, Glu48, and Asp70 were found to be crucial for RNase H activity. Determination of the kinetic parameters for the mutated enzymes using the chemically synthesized nonanucleotide duplex as a substrate demonstrated that these residues are involved in the catalytic site rather than the substrate-binding site. These residues are fully conserved in the amino acid sequences of not only retroviral RTs but also hepadnaviral, plant viral and retrotransposon RTs. This strongly suggests that they are also involved in the active site of these RTs and RT related enzymes.

Amino Acid Sequence↗
PubMed1990

Occurrence of S-(1,2-dicarboxyethyl)-cysteine at position 77 in mutant human lysozyme secreted by Saccharomyces cerevisiae.

A mutant human lysozyme P110, in which Val110 was replaced with Pro, was secreted by Saccharomyces cerevisiae; modification of the cysteine residue at position 77 was found in a purified mutant protein (P110-B) upon primary structure analysis. A peptide fragment containing 15 amino acid residues from Thr70 to Leu84 was obtained by proteolytic digestion of the protein and subsequently isolated by reverse-phase HPLC. This fragment was analyzed by high-resolution fast-atom-bombardment (FAB) mass spectrometry, which showed that 1,2-dicarboxyethyl group was attached to the thiol group of Cys77. This modification was confirmed by comparing it with a sample of chemically synthesized S-(1,2-dicarboxyethyl)-L-cysteine. It was found that the modification caused a disruption of the disulfide bond Cys77-Cys95 in the mutant molecule. These observations, plus structural considerations, suggest that Cys77 and Cys95 either remain uncrosslinked or the disulfide bond Cys77-Cys95, once formed, is opened during the final step in the folding of human lysozyme in vivo.

Amino Acid Sequence↗
PubMed1990

Combination of heteronuclear 1H-15N and 1H-13C three-dimensional nuclear magnetic resonance experiments for amide-directed sequential assignment in larger proteins.

A new strategy for the sequential assignment of backbone proton resonances in larger proteins involving a unique combination of four types of heteronuclear three-dimensional (3D) NMR spectroscopies is reported. This method relies on the uniform labeling of amide nitrogens with 15N and of alpha-carbons with 13C. Heteronuclear 1H-15N TOCSY-HMQC and NOESY-HMQC experiments can reveal connections between cross-peaks arising from the NHi-C alpha Hi-1 and NHi-C alpha Hi connectivities in the finger-print region in in general. They also specifically reveal the sequential amide-amide connectivities among the amide cross-peaks for the alpha-helices. Heteronuclear 1H-13C HMQC-TOCSY and HMQC-NOESY experiments can reveal connections between cross-peaks arising from the NHi-C alpha Hi and NHi+1-C alpha Hi connectivities in the finger-print region in general. The combination of the two sets of results reveals the complete unambiguous sequential connection of cross-peaks for the proton resonances in the peptide backbone. The application of the new strategy is reported for a protein, ribonuclease H, with a molecular weight of 17.6 kDa.

Amino Acids↗
PubMed1990

[An autopsied case of infective endocarditis with cardiac tamponade due to myocardial rupture].

Since it is very rare that cardiac tamponade due to myocardial rupture caused by infective endocarditis, occurs we are reporting this case. A 62 year old man, who had underlying diseases of pneumoconiosis and hypertensive heart disease, visited Chikuho Rosai Hospital complaining of chest oppression and general fatigue on Feb. 7, 1987. He was diagnosed as having ischemic heart disease by electrocardiogram. Two days later, he suddenly had chills and a fever, and the laboratory data showed leukocytosis and a positive C-reactive protein (CRP). The echo cardiogram showed mitral regurgitation (MR) and aortic regurgitation (AR), but neither vegetation nor pericardial effusion was observed. On Feb. 16, he was admitted with shock, and he died the next day. The blood cultures grew gram-positive cocci, respectively. From the clinical symptoms, chest roentgenogram and electrocardiogram, we suspected a cardiac tamponade. On autopsy findings, though coronary arteries were intact, the aortic valves had severe valvular adhesions, calcifications and hypertrophies. The rupture hole was observed in the left ventricles, which was just under the aortic valve through the pericardiac space. It seemed that he died of a cardiac tamponade due to the outflow of blood from this hole. On histopathologic findings of the cardiac wall, gram-positive cocci and many of neutrophils were observed.

Cardiac Tamponade↗
PubMed1990

[Study of the intracellular contractile mechanism of the urinary bladder smooth muscle using skinned fiber technique].

The intracellular contractile mechanism of the urinary bladder smooth muscle was studied using the saponin-treated skinned fiber in which cell membrane was chemically removed. The chemically skinned bladder muscle showed a tension development which was dependent on Ca2(+)-concentration. The minimal Ca2(+)-concentration for the tension development was 2 X 10(-7) M Ca2+. The maximal tension was induced at 10(-5) M. This maximal tension was approximately the same as the K(+)-induced tension development observed in the intact muscle. In addition, SDS-polyacrylamide gel electrophoresis showed that the contractile proteins were still preserved in the saponin-treated bladder smooth muscle. The Ca2(+)-concentration-tension response curve shifted to the left with an increase in MgATP concentration (from 3 mM to 7 mM), indicating that the sensitivity of the skinned muscle was affected by MgATP. Mg2+ above 6 mM caused a slow tension development by itself in the absence of Ca2+. Ca2(+)-induced tension development was blocked by the addition of W-7 (calmodulin antagonist). This result suggested that calmodulin (Ca2(+)-binding protein) regulates the actin-myosin interaction in the urinary bladder smooth muscle. Caffeine solution (25 mM) caused a rapid tension development in the skinned bladder smooth muscle which was loaded with Ca2(+)-concentration, however, this tension development decreased when the loaded Ca2(+)-concentration exceeded 10(-6) M. It seems from this result that "Ca-induced-Ca release mechanism" also exists in the urinary bladder smooth muscle.

Adenosine Triphosphate↗
PubMed1989

Overproduction and preliminary crystallographic study of ribonuclease H from Escherichia coli.

To facilitate the preparation of ribonuclease H from Escherichia coli in an amount sufficient for crystallographic studies, we have constructed an overproduction system for the enzyme. The structural gene for the enzyme was subcloned from pSK750 (Kanaya, S., and Crouch, R. J. (1983) J. Biol. Chem. 258, 1276-1281) to make a plasmid vector pPL801, in which the gene was under the control of bacteriophage lambda PL promoter. Thermal induction of the gene accumulated the enzyme in E. coli N4830-1 to approximately 8% of the total cytosolic protein. The level of production of the enzyme in N4830-1 harboring pPL801 was 14 mg/liter culture, which was 3000 times as high as that in the host cell. The enzyme was purified with a yield of more than 80% and crystallized by utilizing the property that the solubility of the enzyme decreased at pH values close to its isoelectric point (pI = 9). Crystals were grown by successive seeding (hanging drop method) for x-ray crystallographic analysis. The crystals belong to space group P212121 with unit cell dimensions of alpha = 44.1 A, b = 87.0 A, c = 35.5 A and contain one molecule in an asymmetric unit. They diffracted x-rays beyond 2.5 A resolution.

Bacteriophage lambda↗
PubMed1989

Quantitative correlation between cardiovascular and plasma epinephrine response to mental stress.

To investigate the quantitative correlations between cardiovascular and endogenous catecholamine response to mental stress, we gave a mental arithmetic test to 20 young healthy men. A direct and non-invasive haemodynamic measurement was performed by serial M-mode echocardiography. Heart rate, blood pressure, cardiac output, stroke volume, ejection fraction, left ventricular end-systolic pressure-volume ratio and plasma epinephrine increased over the baseline period during the test. The peripheral resistance and left ventricular end-systolic volume decreased, whereas left ventricular end-diastolic volume and plasma norepinephrine were unaltered. Furthermore, the degree of change in each haemodynamic parameter showing significant reaction, was well correlated with that of the increase in plasma epinephrine. The data suggest that acute mental stress induces endogenous epinephrine secretion resulting in a beta-adrenergic activated state in the cardiovascular system, namely, positive chronotropism, positive inotropism and vasodilatation.

Adult↗
PubMed1989

Tryptic digestion of NADH dehydrogenase from alkalophilic Bacillus.

The alkalophile NADH dehydrogenase (NADH: 2,6-dichlorophenolindophenol oxidoreductase) [EC 1.6.99.3] consists of two identical subunits of 65 kDa, and each subunit contains the catalytic and liposome-binding regions. On treatment with trypsin, the polypeptide exhibiting the liposome-binding property in one of the subunits was digested to form an enzymatically active hetero-dimer (40 and 65 kDa), and then the polypeptide in the other subunit was digested to form an active homo-dimer (40 and 40 kDa). The hetero-dimer bound to liposomes, but the homo-dimer did not. Kinetic analysis showed that removal of one or two of the polypeptides in the enzyme slightly affects its kinetic parameters. For all the enzyme species, NAD inhibited competitively with respect to NADH and non-competitively with respect to 2,6-dichlorophenolindophenol. The partially determined amino acid sequence of this alkalophile enzyme suggested that (i) a long random-coiled peptide (58 amino acid residues) or a portion of the peptide is located between the polypeptides with liposome-binding and catalytic properties, (ii) the polypeptide exhibiting liposome-binding property is in the amino terminal region of the enzyme, (iii) the amino acid sequences around the subtilisin and trypsin cleavage sites of the peptide are hydrophilic and on the surface of the protein molecule and therefore are susceptible to digestion, and (iv) the FAD-binding site is located near the amino terminal region of the catalytic region.

Amino Acid Sequence↗
PubMed1989

[Treatment of female acute cystitis with a single dose of cefminox].

Thirty six female patients with acute cystitis were treated with one shot intravenous injection of 1 g cefminox. Clinical efficacy was evaluated based on extent of subjective symptoms, pyuria and bacteriuria. Of 36 patients, an excellent efficacy was shown in 32 cases, moderate in 3 cases and poor in 1 case. This poor case was diagnosed as complicated urinary tract infection because of right vesicoureteral reflux. Therefore, the overall effectiveness rate of this treatment for acute uncomplicated cystitis in women was 100%. Single dose chemotherapy with an adequate antibiotic is considered a useful treatment for female acute cystitis.

Acute Disease↗
PubMed1988

Cloning and sequence analysis of cDNA for rat liver uricase.

We have isolated cDNA clones for rat liver uricase using an oligonucleotide corresponding to the N-terminal sequence of 8 amino acids. The nucleotide sequences of the cDNAs have been determined, and the amino acid sequence of the protein deduced. A 867-base open reading frame coding for 289 amino acids, corresponding to a molecular mass of 33,274 daltons, was confirmed by matching eight sequences of a total of 53 amino acids from peptide sequence analyses of the fragments generated by lysyl endopeptidase digestion of purified rat liver uricase. The deduced amino acid sequence of rat liver uricase shares 40% homology with that of soybean nodulin-specific uricase and has an N-terminal extension of 7 amino acids. In contrast, soybean uricase has a C-terminal extension of 12 amino acids, which is presumably the result of local gene duplication. Completely different N- and C-terminal structures of the two uricases suggest that the signals for targeting the proteins to the peroxisome are not located on the terminal continuous stretches of amino acids.

Amino Acid Sequence↗
PubMed1988

Molecular cloning and nucleotide sequence of Thermus thermophilus HB8 trpE and trpG.

The trpE gene of Thermus thermophilus HB8 was cloned by complementation of an Escherichia coli tryptophan auxotroph. The E. coli harboring the cloned gene produced the anthranilate synthase I, which was heat-stable and enzymatically active at higher temperature. The nucleotide sequence of the trpE gene and its flanking regions was determined. The trpE gene was preceded by an attenuator-like structure and followed by the trpG gene, with a short gap between them. No other gene essential for tryptophan biosynthesis was observed after the trpG gene. The amino-acid sequences of the T. themophilus anthranilate synthase I and II deduced from the nucleotide sequence were compared with those of other organisms.

Amino Acid Sequence↗
PubMed1987

Protein quality in feeding low birth weight infants: a comparison of whey-predominant versus casein-predominant formulas.

Growth (delta weight, delta length, delta head circumference, and delta skinfold thickness), nitrogen retention, and chemical indices of metabolic tolerance (BUN concentration and acid-base status; plasma amino acid concentrations including free and bound cyst(e)ine; urinary excretion of sulfur amino acids) were determined serially in low birth weight infants (900 to 1,750 g) fed formulas differing only in protein quality. One contained unmodified bovine milk protein (a ratio of whey proteins to caseins of 18:82); the other contained modified bovine milk protein (a ratio of whey proteins to caseins of 60:40). Both provided protein and energy intakes, respectively, of approximately 3.4 g/kg/d and 120 kcal/kg/d. Neither weight gain nor the rate of increase in length, head circumference, and skinfold thickness differed between the two groups. Nitrogen retention of the two groups also did not differ. Although BUN concentration and blood acid-base status did not differ, there were differences in the plasma concentrations of some amino acids. Plasma tyrosine concentration was higher in infants fed the casein-predominant protein, and plasma threonine concentration was higher in infants fed the whey-predominant protein. Neither plasma-free nor bound cyst(e)ine concentration differed between the two groups, but the greater cyst(e)ine intake of the whey-predominant group resulted in greater cyst(e)ine retention; this was accompanied by greater urinary taurine excretion, a reflection of greater taurine stores.

Acid-Base Equilibrium↗