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Biomedical subjects

Y Usui

Publications and source records attributed to Y Usui.

At least 127 records · Page 7Linked to original sources
PubMed1985

Doppler measurement of the pressure drop caused by arterial stenosis: an experimental study: a case report.

A stenotic arterial lesion which reduces the cross-sectional area of the artery causes an increased velocity and, as a consequence, a loss in kinetic energy and a pressure drop. A simplified formula, derived from the Bernoulli principle, relates the pressure drop to the maximum velocity of the blood flow in the stenotic segment: delta P (mmHg) = 4 Vmax2 (m/sec). This formula has been validated for stenosis of cardiac valves. Aim of our study was to test the hypothesis that this formula applies in the major arteries using Doppler ultrasound with spectrum analysis. In our experiments we created artificial graded stenoses of varied geometry in the thoracic aorta of dogs. Invasive pressure measurements were obtained using intra-arterial needles on both sides of the stenosis. A Doppler signal was obtained with a 2.5 MHz CW probe, insonating the stenotic area from a distance, with an almost parallel approach. In these conditions the maximum Doppler frequency shift is an accurate estimate of the maximum flow velocity, according to the Doppler equation. We compared the Doppler derived (delta P = 0.36 Fmax2) and the invasive measurements of pressure drops. Our results show a highly significant correlation between the intra-arterial and the Doppler measurements of the pressure drops caused by arterial stenoses and encourage efforts in applying similar techniques in the noninvasive evaluation of vascular patients.

Animals↗
PubMed1985

[Assessment of regional wall motion of the hypertrophic heart by phase analysis of thallium-201 images].

Combined technique with gated planner thallium (Tl)-201 images and gated cardiac pool images were applied to evaluate cardiac hypertrophy and regional wall motion for 13 persons. These subjects consisted of four normal persons, four patients with hypertrophic obstructive cardiomyopathy (HOCM) and five patients with asymmetrical apical hypertrophy (AAH). The Tl-201 image and cardiac pool image were obtained using the gated technique, in which the R-R interval was divided into 16 parts, in the 30 degree left anterior oblique projection. The region of interest (ROI) in the left ventricle was defined by the threshold method and radially divided into 16 segments in the center of the left ventricular area. The count ratio, considered as an indicator of regional myocardial contractility, was calculated using the formula (EDC-ESC/EDC) in each ROI. The functional image and histogram, an indicators of the synchronization of left ventricular wall motion, were constructed by the fluctuation of the phase distribution in volume curves of Tl-201. These indicators were evaluated for the normals and the two groups of patients. The count ratio indicated a higher value in the region of the left ventricular free wall and the cardiac apex in the normals, HOCM and AAH. The count ratio at the septal region indicated a lower value in HOCM, in spite of marked septal hypertrophy. A significant fluctuation of the phase distribution was demonstrated in the septal region in HOCM, and also at the apical region in AAH.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

[Studies on minimum antibiotic concentration of cephapirin against clinically isolated strain SMK-101 of Klebsiella pneumoniae].

Using strain SMK-101 of K. pneumoniae its nephelometric absorbencies, viable cell numbers and morphological changes were studied during the time course cultured in a broth medium containing cephapirin (CEPR), and following results were obtained. After 1 to 3 hours culture in the presence of varying concentration of the antibiotic, the absorbency increased in spite of without change in the viable cell number. Morphologically, elongation and swelling of central portion of the cells were observed though differences of the degree of these findings varied depending upon the concentration of the antibiotic. At the concentration higher than 1/4 MIC, indistinct structure was shown in cytoplasm. After 6 hours culture, 3 directions of absorbence curves, ascending, descending and no change, and 2 directions of viable cell numbers, decreasing and increasing were shown. As the morphological changes of the cells, filamentation, leaking of intracellular components were shown in rather upper concentration of the antibiotic. Fission was demonstrated around the end of cells cultured in rather lower concentration of the antibiotic. After 9 hours culture, absorbency and viable cell number were parallel. In this period, structural findings of cytoplasm became clear and fission was also demonstrated by light microscope except for the cells cultured in more than 1 MIC of the antibiotic. After 24 hours culture, both absorbency and viable cell number increased again and fission was observed in the cell which showed filamentation in 1 MIC of the antibiotic.

Cephalosporins↗
PubMed1985

[Studies on sub-MIC activities of beta-lactam antibiotics and aminoglycoside antibiotics against clinically isolated strain].

Sub-MIC range of 8 kinds of beta-lactam antibiotics and 3 kinds of aminoglycoside antibiotics against strain of Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa isolated from clinical source were determined by nephlometic method, and following results were obtained. When 10 strains of S. aureus tested to ampicillin (ABPC), hetacillin (IPABPC), mecillinam (MPC), cephalexin (CEX), cefotaxime (CTX), latamoxef (LMOX), cefatrizine (CFT), cephapirin (CEPR), gentamicin (GM), dibekacin (DKB) and amikacin (AMK), ratio of MIC to MAC were 36.8, 53.6, 156.8, 29.6, 61.6, 34.4, 50.0, 111.2, 9.2, 20.0 and 13.6, respectively. When 10 strains of K. pneumoniae tested to MPC, CEX, CTX, LMOX, CFT, CEPR, GM, DKB and AMK, ratio of MIC to MAC were 409.6, 10.4, 34.4, 123.2, 39.2, 167.2, 5.2, 5.6 and 13.2, respectively. When 10 strains of P. aeruginosa tested against CTX, LMOX, GM, DKB and AMK, ratio of MIC to MAC were 16.8, 38.4, 6.8, 3.2 and 10.4, respectively.

Aminoglycosides↗
PubMed1984

Effects of fibronectin on the compact colony formation in staphylococci.

Fifty-two unencapsulated strains of Staphylococcus aureus, including strains of Wood 46 and Cowan I, formed compact colonies in fibronectin -soft agar. However, 20 encapsulated strains of Staphylococcus aureus and 50 strains of Staphylococcus epidermidis showed diffuse growth in the medium. The results suggest that another possible cellular factor, other than protein A, is involved in the binding of the cell surface with fibronectin and that it would be one of factors in forming compact colonies in serum-soft agar.

Agar↗
PubMed1984

The evaluation of asymptomatic arterial occlusive disease of the legs using an exercise test.

The Doppler-derived ankle pressure index (API) is a useful indicator of the necessity for peripheral vascular reconstruction of the lower extremities. But the API at rest dose not reflect the functional capacity of leg circulation, especially in the early stage of disease. Therefore, an asymptomatic but hemodynamically significant lesion in one leg is sometimes missed by pressure measurement at rest when there is a severe lesion with symptoms in the other leg. In this study, the API not only at rest but also after exercise was measured in twenty normal subjects and thirty-two patients with angiographically proven arteriosclerosis obliterans. About 60% of the patients had unilateral symptoms, although they had significant disease bilaterally. The API after exercise proved to be more sensitive than the API at rest and may be useful in assessing asymptomatic legs of such patients and determining their surgical indication.

Aged↗