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Biomedical subjects

R Yamaguchi

Publications and source records attributed to R Yamaguchi.

At least 181 records · Page 10Linked to original sources
PubMed1987

[Quantitative evaluation of regional myocardial blood flow by digital subtraction angiography: correlations with exercise electrocardiography and Tl-201 myocardial scintigraphy].

We previously reported that the contrast disappearance half-life (T1/2) derived by the computerized washout analysis of digital subtraction coronary arteriograms provides a useful index for quantitatively evaluating regional myocardial blood flow. In the present study, we further evaluated the clinical usefulness of T1/2, comparing it with exercise electrocardiography and exercise thallium-201 myocardial scintigraphy. The study subjects consisted of 25 patients with angina pectoris and 14 patients with normal coronary arteries. Following the manual injection of contrast media into the left anterior descending coronary artery (LAD), a time-density curve was generated in the sectors of the myocardium which were perfused by the LAD and the T1/2 was calculated. T1/2 values correlated closely with double product (r = -0.73). They were significantly greater in patients with exercise-induced ST depression (8.3 +/- 1.0 vs 5.8 +/- 0.7, p less than 0.005). In addition, there was a good correlation between T1/2 values and washout ratio as determined by exercise thallium-201 myocardial scintigraphy, with r = -0.83. Although T1/2 values were within the normal range (mean +/- 2SD of control subjects) in all patients with LAD stenosis of 50 percent or less, these values were abnormally increased, exceeding the normal range, in 11 of the 12 patients with stenosis of 90 percent or more. Compared with exercise electrocardiography, T1/2 values were abnormally prolonged in 11 of the 13 patients with exercise-induced ST depression. Compared with exercise thallium-201 myocardial scintigraphy, T1/2 values were abnormally prolonged in seven of the nine patients with transient perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1986

Action of zinc on bone metabolism in rats. Increases in alkaline phosphatase activity and DNA content.

The effects of zinc on the enzymes of femoral tissue were investigated in weanling rats that had been given zinc sulfate (1.0 mg Zn2+/100 g body wt) p.o. for 3 days. Administration of zinc caused a marked elevation of alkaline phosphatase and acid phosphatase activities, whereas it did not cause significant changes in succinate dehydrogenase, 5'-nucleotidase, ATPase, pyrophosphatase and beta-N-acetylglucosaminidase activities. The effect of zinc was greater on alkaline phosphatase of the femoral diaphysis. Zinc content of the femoral diaphysis was raised significantly by administration of zinc. The addition of zinc in concentrations of 10(-2)-10(2) microM did not produce a significant increase in alkaline phosphatase activity in the femoral diaphysis, indicating that zinc could not activate the enzyme. Administration of cycloheximide or actinomycin D completely inhibited the increase in alkaline phosphatase activity produced by administration of zinc. DNA content of the femoral diaphysis, but not epiphysis, was increased markedly by administration of zinc. The increases in both alkaline phosphatase activity and DNA content of the femoral diaphysis were not caused by administration of copper, manganese, cobalt, nickel and chromium(III). The present investigation suggests that zinc may induce the increase in alkaline phosphatase related to DNA synthesis and, as a result, stimulate bone growth.

Alkaline Phosphatase↗
PubMed1986

Analysis of thromboxane B3 converted from eicosapentaenoic acid in human platelet rich plasma by gas chromatography/mass spectrometry.

Gas chromatographic mass spectrometric determination of thromboxane B3 (TXB3) synthesized from platelet is described. Eicosapentaenoic acid (EPA) was added to human platelet rich plasma and after the reaction the exstraction was carried out. Plasma thromboxanes were run through an Amberlite XAD-2 and SEP-PAK silica cartridge, and then chromatographed using silicagel thin layer plate to remove interfering materials, such as 6-keto-prostaglandin F1 alpha. Extracted thromboxanes were converted into the methoxime-dimethylisopropylsilylmethyl ester derivatives and they were measured by gas chromatography/ammonia chemical ionization mass spectrometry. Three peaks were obtained on the gas chromatogram which were presumed to be 3-series metabolite product TXB3 and their related substances. Results indicates the human platelet may easily convert EPA to TXB3 by adding EPA to PRP without adding arachidonic acid.

Ammonia↗
PubMed1986

[Left ventricular function in hypertrophic cardiomyopathy: a Tc-99m radionuclide angiographic study during exercise].

Hypertrophic cardiomyopathy (HCM) generally shows increased systolic function of the left ventricle at rest, although patients with HCM often have decreased exercise tolerance and develop dyspnea or chest pain. The present study was to investigate of left ventricular (LV) function during exercise in 26 patients with HCM using Tc-99m equilibrium angiocardiography, and to elucidate the mechanism of impaired functional reserve during exercise. Controls consisted of 11 normal volunteers and 12 patients with chest pain syndrome who had no abnormality on coronary arteriography or left ventriculography. In patients with HCM, LV ejection fraction decreased from 65 +/- 8 (mean +/- SD)% at rest to 59 +/- 18% at peak exercise, in contrast to an increase among controls (from 56 +/- 9% to 64 +/- 9%). As compared with resting values, cardiac output increased to 168 +/- 24% at peak exercise in HCM, but the increase was significantly less than that in controls (215 +/- 47%). Stroke volume decreased gradually to 83 +/- 16% during exercise in HCM, while it increased to 114 +/- 10% at an exercise level of half intensity, and it decreased slightly to 106 +/- 16% at peak exercise. LV end-systolic volume decreased among controls to 78 +/- 27% at peak exercise, but remained unchanged in HCM (118 +/- 58%). An increase in peak ejection rate at peak exercise was less in HCM than in controls (143 +/- 26% vs 170 +/- 42%). No significant differences were observed between the two groups concerning changes in indices of LV diastolic function including LV end-diastolic volume, peak filling rate or 1/3 filling rate during exercise. In the analysis of LV function curves, pulmonary arterial diastolic pressure increased to a greater extent in HCM than in controls (19 +/- 6 mmHg vs 11 +/- 6 mmHg); whereas, an increase in the stroke work index was less in HCM (80 +/- 26 g.m/m2/beat vs 121 +/- 21 g.m/m2/beat) at peak exercise. Thus, the LV function curve shifted downward and to the right in patients with HCM. The above findings indicate that LV functional reserve during exercise is impaired, especially as to systolic function in patients with HCM, while deterioration of diastolic function may be partly compromised by elevated filling pressure.

Cardiomyopathy, Hypertrophic↗
PubMed1985

Determination of the complete nucleotide sequence of the Brevibacterium lactofermentum plasmid pAM330 and the analysis of its genetic information.

The complete nucleotide sequence of the plasmid pAM330 derived from Brevibacterium lactofermentum ATCC 13869 was determined using the dideoxy chain termination method. Analysis of the sequence allowed us to observe seven open reading frames, one of which showed the presence of the promoter and the Shine-Dalgarno (SD) sequences upstream from the initiation codon.

Base Sequence↗
PubMed1985

[Dysfunction of Carpentier-Edwards porcine mitral bioprosthesis causing a musical systolic murmur: a report of two cases].

Two patients with disruption of Carpentier-Edwards porcine mitral bioprosthesis presenting with a musical systolic murmur were reported. The two patients noted sudden development of a loud musical murmur 4 (Case 1) and 6.5 (Case 2) years after surgery. Case 1 had associated heart failure. Phonocardiogram disclosed a loud musical systolic murmur with regular vibrations at 230-240 Hz in Case 1, and 250-260 Hz in Case 2. In Case 1, echocardiography demonstrated fine fluttering of the porcine mitral valve at the same frequency as the murmur. Doppler echocardiography revealed characteristic Doppler signals from the porcine valves at a frequency of 250-300 Hz with several harmonics above and below the baseline. In addition, in Case 2, similar Doppler signals were obtained from the aortic walls, ventricular septum and posterior wall of the left ventricle. In both cases, left ventriculograms demonstrated grade 3 mitral regurgitation without paravalvular leakage, and at surgery, the porcine bioprosthesis showed a tear in one of markedly thinned cusps, without evidence of calcification. It was considered that a torn cusp was the source of the murmur, and this, in association with the resonance of the entire heart, produced the loud musical murmur. Thus, a musical systolic murmur is suggested to be one of important signs of dysfunction of porcine bioprosthesis.

Adult↗
PubMed1984

Kinetic studies on the cleavage of oligouridylic acids and poly U by bovine pancreatic ribonuclease A.

Kinetic parameters, Km and Vmax for the transesterification of oligouridylic acid, (Up)nU greater than p (n=0-4), by RNase A were measured spectrophotometrically at pH 7.0 and 25 degrees C. The kinetic parameters, pKm and log Vmax increased with increase in the chain length (n), and seemed to be almost constant with substrates having n greater than or equal to 2. The contribution of each subsite to the binding was estimated according to Hiromi's theory. The subsite affinities for (B1, R1, P1)+(B2, R2, P2) and (B3, R3, P3) are 8.03 kcal and 0.72 kcal/mol, respectively, and those for (B4, R4, P4) and (B5, R5, P5) are less than 0.5 kcal/mol. Therefore, we postulate that the size of the RNase A active site is about 3 nucleotides in length. Transesterification of poly U by RNase A was followed spectrophotometrically. The reaction is markedly influenced by ionic strength. At lower ionic strength, the v0-S curve of poly U cleavage was sigmoidal and cooperative, and it became less cooperative at higher ionic strength. Since the estimated Vmax value for poly U cleavage at ionic strength of 0.1 was more than 20 times larger than that of oligouridylic acids cleavage, we propose a non-specific interaction of poly U anion with cationic groups on the surface of the enzyme, modulating the conformation of active site, and thus increasing the activity at low ionic strength. The interaction decreases at higher ionic strength due to the interaction of counter anions with the non-specific sites.

Animals↗
PubMed1984

Immunoglobulin classes of anti-Sendai virus antibody detected by ELISA in infected nude mouse serum.

Sendai virus-infected nude mouse sera obtained on the seventh day after infection or later, in which anti-Sendai virus antibodies were undetectable by hemagglutination-inhibition and neutralization tests, were found to be reactive with the virus antigen by ELISA using horseradish peroxidase-conjugated anti-mouse IgG rabbit IgG. The reactivity was blocked by rabbit anti-Sendai virus antiserum and was not observed against influenza virus which served as a control antigen. Anti-Sendai virus antibody activity of fractions from Sephadex G-200 gel filtration was detected in the IgM fraction when anti-mouse mu chain-specific antiserum was used and in both IgG and IgM fractions when heavy and light chain-specific anti-mouse IgG serum was employed in ELISA. ELISA of the fractions from protein A-Sepharose affinity chromatography of Sendai virus-infected nude mouse sera showed that the eluates at pH 6.0 and pH 3.5 contained IgG1 and IgG2b anti-Sendai virus anti-bodies, respectively, and that the eluate at pH 4.5 contained both IgG2a and IgG3 antibodies.

Animals↗
PubMed1984

Immunological and genomic analyses of two serotypes of avian paramyxovirus isolated from wild ducks in Japan.

A total of 11 avian paramyxoviruses isolated from migrating feral ducks in Niigata, Japan, were characterized by serological and genomic analyses. Hemagglutination inhibition and immuno-double-diffusion tests with antisera specific for the isolated hemagglutinin-neuraminidase polypeptides of reference strains indicated that, of these, eight isolates possessed hemagglutinin-neuraminidase antigen closely related to that of duck/Hong Kong/D3/75, and the remaining three isolates possessed antigen closely related to that of duck/Hong Kong/199/77. RNA analysis of the eight isolates identified serologically as duck/Hong Kong/D3/75 by oligonucleotide mapping revealed that these isolates were genetically very similar to each other but different from the reference strain and isolates reported previously. The oligonucleotide maps of duck/Hong Kong/199/77-like isolates appeared to be very similar to each other, suggesting the same origin, but not to the duck/Hong Kong/199/77 virus.

Animals↗