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Biomedical subjects

M Takeuchi

Publications and source records attributed to M Takeuchi.

At least 433 records · Page 24Linked to original sources
PubMed1996

Intracoronary papaverine induced myocardial lactate production in patients with angiographically normal coronary arteries.

Although intracoronary papaverine has been widely used for the measurement of coronary flow reserve, little is known concerning whether papaverine may produce deleterious metabolic changes in humans. We investigated the effect of papaverine on lactate metabolism in 28 patients with normal coronary arteries. We continuously monitored phasic coronary flow velocity in the proximal left anterior descending coronary artery using Doppler guidewire. We also obtained paired samples of arterial and coronary sinus blood for the measurement of lactate at control and at 1 min after administration of 10 mg of intracoronary papaverine. There were no serious side effects during papaverine infusion. Sixteen patients showed ST-T abnormalities after papaverine. The QTc interval increased from 450 +/- 42 msec to 571 +/- 58 msec (P < 0.001). Average peak velocity increased significantly (% increase: 198.5 +/- 87.8%, range: 27.8-374.1%) after papaverine. Although intracoronary papaverine produced no significant change in arterial lactate levels (8.5 +/- 4.0-8.8 +/- 5.0 mg/ml), it induced a significant increase in coronary sinus lactate levels (5.4 +/- 3.2-15.3 +/- 8.2 mg/ml, P < 0.001). Lactate extraction ratio decreased significantly (36.4 +/- 18.4--82.2 +/- 58.4%, P < 0.001), and all patients showed net lactate production (-3.9--198.0%) after papaverine. There was weak but significant correlation between lactate extraction ratio after papaverine and coronary flow reserve (R2 = 0.15, P < 0.05). There was no correlation between lactate extraction ratio and QTc interval after papaverine. The mean value of lactate extraction ratio was not different in patients with ST-T abnormalities induced by papaverine compared to those without. These results demonstrate that intracoronary papaverine induces myocardial lactate production irrespective of the degree of coronary flow reserve and electrocardiographic changes in patients with normal coronary arteries. A safer and more reliable agent is needed for the measurement of coronary flow reserve.

Adult↗
PubMed1996

Development of primary hypothyroidism with antithyroglobulin, antiperoxidase, and blocking-type thyrotropin receptor antibodies after radiation therapy for neuroblastoma.

We describe a girl with hypothyroidism and blocking-type thyrotropin receptor antibodies that developed after chemotherapy and irradiation of the neck region for neuroblastoma. Results of thyroid studies before treatment were normal. Twenty months after completion of treatment, the girl had hypothyroidism with high titers of blocking-type thyrotropin receptor antibodies, antithyroglobulin, and antiperoxidase antibodies.

Antibodies↗
PubMed1996

Peptide-mediated suppression of experimental autoimmune uveoretinitis in mice: development of a peptide vaccine.

Experimental autoimmune uveoretinitis (EAU) is an animal model of antigen-specific, Th cell-mediated, organ-specific autoimmune disease. EAU is induced by immunization of B10.A mice with interphotoreceptor retinoid-binding protein (IRBP). Pre-treatment with synthetic peptide 518-529 derived from IRBP prevented IRBP-mediated EAU. This was accompanied by augmentation of the IRBP-specific IgG1 antibody (Th2) response and down-regulation of the IRBP-specific IgG2a (Th1) response. Consistent with this is the observation that two of two T cell lines established from p518-529-primed mice produced Th2-type cytokines (IL-4 and IL-10), whereas three of three T cell lines obtained from IRBP-primed mice produced Th1-type cytokines (IL-2 and IFN-gamma). Together this suggests the possibility that p518-529 priming causes a shift from a Th1-to a Th2-dominated immune response, thereby playing a pivotal role in the prevention of IRBP-mediated EAU. Furthermore, co-transfer of cells from a CD4+ p518-529-specific T cell line prevented the development of EAU after adoptive transfer of spleen cells from mice with EAU into normal mice. These findings contribute to our understanding of the mechanism of EAU, particularly with respect to the down-regulation of Th1-initiated inflammation, and may prove valuable for designing a peptide vaccine for EAU in the future.

Adoptive Transfer↗
PubMed1996

Enzymatic properties of mutant enzymes at Trp49 and Tyr57 of RNase Rh from Rhizopus niveus.

In order to establish the role of Tyr57 and Trp49 in the enzymatic reaction of RNase Rh, several mutant enzymes at Tyr57 and Trp49 were prepared by protein engineering and their enzymatic properties were investigated. Among the four mutant enzymes at Trp49 (W49F, W49Y, W49A, and W49I), W49F showed 16% of the activity of the native enzyme, but the others (W49Y, W49A, and W49I) showed greatly decreased activity. The data showed that Trp49 is very important for the enzyme activity. Among 8 mutant enzymes at the 57th position, Y57F and Y57W showed similar enzymatic activity toward RNA to that of the wild-type enzyme, but the others (Y57G, Y57A, Y57V, Y57M, and Y57K) are more active toward RNA and less active toward XpGs. The reason for the apparent increase for RNA activity is discussed from the view point of substrate inhibition. It is noteworthy that W49F and Y57W became more pyrimidine base- and purine base-preferential, respectively.

Amino Acid Sequence↗
PubMed1996

Enzymatic properties of mutant forms of RNase Rh from Rhizopus niveus as to Asp51.

In order to determine the role of Asp51 of RNase Rh from Rhizopus niveus, enzymes with mutations at the 51st position, D51N, D51E, D51Q, D51S, D51T, D51A, and D51K, were prepared, and their enzymatic properties were investigated as to specific activity and base specificity. All the mutant enzymes showed relatively high activity toward poly I and poly C, and markedly reduced activity toward poly A and poly U. In particular, the enzymatic activities toward poly I of D51T and D51S were higher than that of RNase RNAP Rh. Among the mutant enzymes, D51N, D51S, and D51T showed more than ca. 30% of the activity of RNase Rh, when RNA, poly I and poly C were used as substrates, respectively. The substitution of Ala, Glu, or Lys at Asp51 is unfavorable for enzymatic activity. Among XpGs (X = A, G, U, or C), D51N, D51S, and D51T showed higher activity toward GpG then CpG. Therefore, Asp51 in RNase Rh plays a critical role in the adenylic acid preference of RNase T2 family enzymes. Our results obtained with a protein engineering technique provide basic insights into the control of the base specificity of RNase Rh.

Amino Acid Sequence↗
PubMed1996

Characterization of p92, karyopherin beta, co-purified with N-acetylglucosamine-bearing nucleoporins from rat liver nuclear envelopes.

A 92k protein (p92) was purified from the wheat germ agglutinin-Sepharose (WGA-Sepharose) bound fraction of a rat liver nuclear envelope salt-extract by DEAE-5PW and hydroxyapatite HPLCs. Partial amino acid sequence analysis of p92 revealed that it is karyopherin beta, which was found recently in the cytosolic fraction. It was shown using anti-p92 antiserum that the protein is present in the nuclear envelope and cytosolic fractions, in almost the same amounts, but not in other subcellular fractions of rat liver. p92 bound to N-acetylglucosamine bearing nucleoporins (GNPs) on WGA-Sepharose, but not directly to WGA. The amount of p92 found in the rat liver nuclear envelope fraction corresponded to about 10% of the nuclear pore complex in mass, and to as much as 140 mol of p92 per mol of nuclear pore complex. Hydrodynamic analysis of the purified p92 suggested that the molecule is present as a monomer and that it is a rod-shaped molecule. The interaction of p92 and GNPs seemed to be hydrophobic and ionic. Based on these results, the participation of nuclear envelope p92 in protein nuclear transport is discussed.

Acetylglucosamine↗
PubMed1996

Molecular cloning of a novel protein containing the association domain of calmodulin-dependent protein kinase II.

The cDNA of a novel protein, which contains the association domain of alpha isoform of calmodulin-dependent protein kinase II (CaM-kinase II alpha), was cloned from rat skeletal muscle. This protein, called alpha KAP, consisted of 200 amino acid residues with a molecular weight of 22,583. alpha KAP has a highly hydrophobic amino-terminal stretch of 25 amino acids which is absent from CaM-kinase II alpha, suggesting that this protein is either a secretory protein or an integral membrane protein. Northern blot analysis with a probe specific for alpha KAP detected three distinct mRNA species of 4.0, 2.4, and 1.5 kb in rat skeletal muscle. The 4.0- and 2.4-kb RNAs were also detected in heart, and at much lower levels in lung, kidney, and testis. Western blot analysis, using antibody raised against a synthetic peptide corresponding to the carboxyl-terminal 15 amino acids, revealed a single band corresponding in mobility to a molecular weight of 21,000 in crude extracts of both rat skeletal muscle and bacteria transformed with the cDNA, suggesting that no significant post-translational modification, such as excision of the amino-terminal hydrophobic segment, occurred. This, together with the fact that alpha KAP was recovered in the high-speed pellet in skeletal muscle, indicated that this protein may be an integral membrane protein.

Amino Acid Sequence↗
PubMed1996

Deep negative T waves and abnormal cardiac sympathetic image (123I-MIBG) after the Great Hanshin Earthquake of 1995.

The authors report the increased incidence of patients with deep negative T waves without Q wave after the Great Hanshin Earthquake of 1995. Subjects underwent cardiac metaiodobenzyl guanidine (123I-MIBG) imaging, 201Tl scintigraphy, and coronary angiography. Among 2,756 inpatients of the preceding 5-year period, 33 (1.2%) showed the deep negative T waves, whereas 6 of 94 (6.4%; P < 0.001) showed it after the earthquake. Four of six patients had an episode of chest pain. Cardiac metaiodobenzyl guanidine imaging revealed the extent defects in all six patients despite a minimal change of 201Tl image. In addition, cardiac metaiodobenzyl guanidine imaging washout rate was hastened not only in the defect area but also in the nondefect area, which suggested augmented sympathetic activation. Natural disasters can affect the frequency of deep negative T waves, which relate abnormal cardiac sympathetic imaging.

3-Iodobenzylguanidine↗
PubMed1996

Comparative diagnostic value of dobutamine stress echocardiography and stress thallium-201 single-photon-emission computed tomography for detecting coronary artery disease in women.

BACKGROUND: The non-invasive diagnosis of coronary artery disease in women remains a difficult clinical problem. The aim of this study was to investigate the comparative diagnostic accuracy of dobutamine stress echocardiography and stress thallium-201 single-photon-emission computed tomography (SPECT) in women who were suspected to have coronary artery disease. METHODS: We studied 70 consecutive women who had not had a previous myocardial infarction (mean age 65 years) who underwent dobutamine stress echocardiography and quantitative coronary angiography. Sixty-one of the 70 women were also subjected to thallium-201 SPECT, with exercise or dipyridamole administration as the stressor, during the same period. A positive diagnosis was based on the detection of inducible wall motion abnormality and the presence of stress-induced abnormalities of perfusion. RESULTS: No significant complication occurred in any patient during dobutamine stress echocardiography (peak dose 31 +/- 9 micrograms/kg per min, atropine administered to 13 patients, peak heart rate 120 +/- 19 beats/min). Coronary artery disease (> or = 50% diameter stenosis) was present in 20 (29%) patients, nine with one-vessel and 11 with multivessel disease. The sensitivity, specificity and diagnostic accuracy of dobutamine stress echocardiography for detecting coronary artery disease were 75, 92 and 87% respectively. In 61 patients who underwent both stress tests, the sensitivity, specificity and accuracy of dobutamine stress echocardiography and stress thallium-201 SPECT were 72 versus 78%, 91 versus 70% (P < 0.05) and 85 versus 72%, respectively. CONCLUSIONS: Dobutamine stress echocardiography appears to be of comparable sensitivity and higher specificity with stress thallium-201 SPECT for noninvasive detection of coronary artery disease in women.

Adult↗
PubMed1996

Leucobacter komagatae gen. nov., sp. nov., a new aerobic gram-positive, nonsporulating rod with 2,4-diaminobutyric acid in the cell wall.

A new aerobic, gram-positive, nonsporulating rod-shaped organism is described: Strain IFO 15245T (T = type strain) has the following characteristics: the menaquinone contains a side chain with 11 isoprenyl units; the guanine-plus-cytosine content of the DNA is 66.2 mol%; 2,4-diaminobutyric acid, glutamic acid, alanine, glycine, and gamma-aminobutyric acid are present in the cell wall at a molar ratio of ca. 1:1:2:1:1; and glucose and galactose are also present in the cell wall. A comparison of partial 16S rRNA sequences revealed that IFO 15245T represents a distinct line of descent within the gram-positive bacteria with high guanine-plus-cytosine contents. The taxonomic characteristics of this organism are different from those of previously described aerobic, gram-positive, nonsporulating, rod-shaped bacteria. The name Leucobacter komagatae gen. nov., sp. nov., is proposed for this organism. The type strain is strain IFO 15245.

Aminobutyrates↗
PubMed1996

Systematic sequencing of the 283 kb 210 degrees-232 degrees region of the Bacillus subtilis genome containing the skin element and many sporulation genes.

As part of the Bacillus subtilis genome sequencing project, we have determined a 283 kb contiguous sequence from 210 degrees to 232 degrees of the B. subtilis genome. This region contains the 48 kb skin element which is excised during sporulation by a site-specific recombinase. In this region, 310 complete ORFs and one tRNA gene were identified: 66 ORFs have been sequenced and characterized previously by other workers, e.g. acc, ans, bfm, blt, bmr, comE, comG, dnaK, rpoD and sin operons; cwiA, gpr and lysA genes; many sporulation genes and operons, spo0A, spoIIA, spoIIM, spoiiP, spoIIIA, spoIIIC, spoIVB, spoIVCA, spoIVCB and spoVA, etc. The products of 84 ORFs were found to display significant similarity to proteins with known function in data banks, e.g., proteins involved in nucleotide metabolism, lipid biosynthesis, amino acid transport (ABC transporter), phosphate-specific transport, the glycine cleavage system, the two-component regulatory system, cell wall autolysis, ferric uptake and sporulation. However, the functions of more than half of the ORFs (52%, 160 ORFs) are still unknown. In the skin element containing 60 ORFs, 32 ORFs (53%) encode proteins which have significant homology to gene products of the B. subtilis temperate phage phi 105 and/or the defective phage PBSX.

Bacillus subtilis↗
PubMed1996

Effect of dual chamber atrioventricular sequential pacing on coronary flow velocity in a patient with hypertrophic obstructive cardiomyopathy.

Effects of dual chamber AV sequential pacing on coronary flow velocity, especially systolic reversal flow, were tested in a patient with hypertrophic obstructive cardiomyopathy. AV sequential pacing with shorter AV delays reduced the systolic reversal flow in the coronary artery, and improved the pressure gradient of the left ventricular outflow tract.

Cardiac Pacing, Artificial↗
PubMed1996

Inhibitory effects of retinoic acids on androgen-dependent development of neonatal mouse seminal vesicles in vitro.

The effects of retinoic acids (RAs) on development of seminal vesicles (SVs) of neonatal mice were investigated in vitro. SVs from 0-day-old male mice were cultured for 2-6 days in serum-free, chemically defined medium containing transferrin and BSA supplemented with 5alpha-dihydrotestosterone (DHT; 10(-8) M) and insulin (10 microg/ml), alone and in combination. Before culture, SVs from 0-day-old mice consisted of an unbranched epithelium surrounded by mesenchyme. SVs cultured in medium with DHT plus insulin or DHT alone formed numerous epithelial branches after day 2 of culture, whereas epithelial branching did not occur in SVs cultured with insulin alone. All-trans-RA or 13-cis-RA (10(-9)-10(-6) M) added to medium containing DHT plus insulin or DHT alone inhibited epithelial branching in a dose-dependent manner. This inhibitory effect was reversible after removal of the retinoids from the medium on day 4 of culture. These RAs also decreased [3H]thymidine labeling indexes of both epithelium and mesenchyme of SVs cultured in medium with DHT plus insulin or DHT alone and inhibited the increase in their protein contents. 9-Cis-RA was less inhibitory than all-trans-RA or 13-cis-RA on epithelial branching, [3H]thymidine labeling indexes of epithelium and mesenchyme, and protein content of SVs cultured in medium with DHT and insulin. In the absence of DHT (insulin alone), all-trans-RA did not affect either the [3H]thymidine labeling indexes of epithelium and mesenchyme or the protein content of cultured SVs. Reverse transcriptase-PCR demonstrated strong expression of transcripts for mouse RA receptors (RARalpha, RARgamma, and RXRalpha), with lower levels of expression of RARbeta, RXRbeta, and RXRgamma in neonatal SVs. The present results indicate that RAs reversibly inhibit androgen-dependent development of neonatal mouse SVs, most likely through RARs.

Animals↗
PubMed1996

The role of extracellular cations in the development of myogenic contraction in isolated rat small arteries.

The purpose of this study was to determine the roles of extracellular cations (Na+, Ca2+ and K+), membrane K+ channels and Na+/K+ ATPase in the development of myogenic contraction (transmural pressure-induced contraction) in isolated rat skeletal muscle and mesenteric small arteries. The vessels were pressurized under no-flow conditions in a tissue bath. Lumen diameter was measured with a videomicroscopic system. Myogenic contraction was evoked by increasing the lumen pressure from 40 to 100 mmHg. The vessels demonstrated myogenic contraction in low-Na+ (Na+ 1.18 mmol/L) physiological salt solution (PSS), and this was abolished by removing Ca2+ or by applying nifedipine or nisoldipine (10 mumol/L). Neither tetraethylammonium (TEA, 1 mmol/L), Ba2+ (10 mumol/L) nor glibenclamide (1 mumol/L) affected the magnitude of the myogenic contraction. K(+)-free PSS and ouabain (0.1 mmol/L) partially depressed myogenic contraction. In conclusion, myogenic contraction was triggered by a cellular process that requires extracellular Ca2+, but not Na+ or K+. This triggering process is not affected by TEA, Ba2+ or glibenclamide.

Animals↗
PubMed1996

Measurement of left ventricular volume by dual-field conductance catheter in humans--comparison with single-field conductance catheter.

The single-field conductance (SF) method for continuous measurement of left ventricular (LV) volume has achieved widespread use. However, it has been shown theoretically that the ratio between the measured conductance and the actual volume varies between the different interelectrode segments of the catheter due to the convex shape of the equipotential planes at the apex and base. The dual-field conductance (DF) method has recently been introduced and reportedly provides a flatter equipotential plane within the LV. In 11 patients, we compared LV volume measured by biplane cineangiography with conductance volume by the SF and DF methods. Strong correlations were found for both the SF method (r = 0.98) and the DF method (r = 0.99). However, in comparison with the SF method, the DF method gave a regression line with a slope factor, alpha, that was closer to unity, and the intercept of the regression line was small (p < 0.01). The DF method gave a significantly greater segmental stroke volume (SV) in the apex and base than the SF method. The ratio of the DF segmental SV to the SF segmental SV in the apex increased in proportion to the end-diastolic volume (p < 0.05). In conclusion, the DF method may facilitate the accurate measurement of LV volume in the human heart.

Adult↗