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Biomedical subjects

K Awano

Publications and source records attributed to K Awano.

18 recordsLinked to original sources
PubMed2000

Morphology of vulnerable coronary plaque: insights from follow-up of patients examined by intravascular ultrasound before an acute coronary syndrome.

OBJECTIVES: To determine the morphologic features of coronary plaques associated with acute coronary syndrome, we prospectively followed patients with atherosclerotic disease identified by intravascular ultrasound (IVUS). BACKGROUND: Although clinical evaluation of the vulnerable atherosclerotic plaque is important, few data exist regarding the morphology of the vulnerable plaque in clinical settings. METHODS: We examined 114 coronary sites without significant stenosis by angiography (<50% diameter stenosis) in 106 patients. All the sites exhibited atherosclerotic lesions by IVUS. These lesions consisted of 22 concentric and 92 eccentric plaques with a percent plaque area averaging 59 +/- 12%. RESULTS: During the follow-up period of 21.8 +/- 6.4 months (range 1 to 24), 12 patients had an acute coronary event at a previously examined coronary site at an average of 4.0 +/- 3.4 months after the initial IVUS study. All the preexisting plaques related to the acute events exhibited an eccentric pattern and the mean percent plaque area was 67 +/- 9%, which was greater than plaque area in the other 90 patients without acute events (57 +/- 12%, p < 0.05). There was no statistically significant difference in lumen area between two patient groups (6.7 +/- 3.0 vs. 7.5 +/- 3.7 mm2). Among 12 coronary sites with an acute occlusion, 10 sites contained the echolucent zones, eight of these shallow and two deep, likely representing a lipid-rich core. In 90 sites without acute events, an echolucent zone in the shallow portion was seen at only four sites (p < 0.05). CONCLUSIONS: Large eccentric plaque containing an echolucent zone by IVUS can be at increased risk for instability even though the lumen area is preserved at the time of initial study. Compensatory enlargement of vessel wall due to remodeling may contribute to the relatively small degree of stenosis by angiography.

Angina Pectoris↗
PubMed2000

Structure determination and total synthesis of a novel antibacterial substance, AB0022A, produced by a cellular slime mold.

A novel antibacterial substance, AB0022A, was isolated from the cellular slime mold Dictyostelium purpureum K1001. It inhibited the growth of Gram-positive bacteria, and its MICs ranged from 0.39 to 50 microg/ml. Because AB0022A was a highly substituted aromatic compound, we could not determine its structure based on only its physico-chemical and spectral data. We therefore used a dehalogenated derivative from AB0022A and deduced that its structure was 1,9-dihydroxy-3,7-dimethoxy-2-hexanoyl-4,6,8-trichlorodibenzofuran . To confirm this structure, we synthesized the compound having the deduced structure. The synthetic compound was identical to naturally occurring AB0022A.

Animals↗
PubMed1999

(3-substituted benzyl)thiazolidine-2,4-diones as structurally new antihyperglycemic agents.

A series of 3-[(2,4-dioxothiazolidin-5-yl)methyl]benzamide derivatives was prepared as part of a search for antidiabetic agents. A structure-activity relationship study of these compounds led to the identification of 5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[4-(trifluorome thyl)-phenyl]methyl]benzamide (KRP-297) as a candidate drug for the treatment of diabetes mellitus.

Animals↗
PubMed1998

[Severe pulmonary hypertension due to mitral regurgitation without overt sign of congestive heart failure: a case report].

A 49-year-old man was found to have a heart murmur at a local hospital and was referred to our hospital for further examination. Although he had no signs of congestive heart failure, echocardiography and cardiac catheterization showed severe pulmonary hypertension caused by severe mitral regurgitation. Mitral valve replacement was performed, followed by reduction of pulmonary artery pressure. This patient had an unusual combination of no signs of lung congestion despite severe mitral regurgitation with pulmonary hypertension.

Echocardiography↗
PubMed1997

Three-dimensional reconstruction of intravascular ultrasound images of coronary stents using an ECG-gated pull-back device.

Three-dimensional reconstruction (3D-R) of intravascular ultrasound (IVUS) images is not yet satisfactory because of artifacts caused by cardiac movement. This problem can be overcome with a new device, an electrocardiographic (ECG)-gated pull-back system. Using this device a catheter is pulled back stepwise gated by the ECG, and IVUS dynamic images of an entire cardiac cycle are acquired at each step. We performed 3D-R of IVUS images of stents using this new device in six patients with Palmaz-Schatz coronary stent implantation. We obtained precise 3D images in all cases, and stent structure was visualized in detail. In conclusion, use of an ECG-gated pull-back device enables precise 3D-R of IVUS images and provides useful information on the coronary artery.

Aged↗
PubMed1996

Exercise beta-methyl iodophenyl acid (BMIPP) and resting thalium delayed single photon emission computed tomography (SPECT) in the assessment of ischemia and viability.

To clarify the significance of exercise BMIPP (beta-methyl iodophenyl pentadecanoic acid) and resting T1 delayed single photon emission computed tomography (SPECT) in the assessment of ischemia and viability, we studied maximal exercise-loading BMIPP SPECT following rest-injected T1 3 h SPECT in 11 control subjects, 20 patients with effort angina and 38 patients with old myocardial infarction. The left ventricular wall on ECT was divided into 9 segments. BMIPP and T1 uptake were scored as 0 = normal, 1 = reduced, 2 = severely reduced, or 3 = absent. Discordance was defined as when segments with a reduced BMIPP uptake had a better resting T1 uptake. Significant coronary artery stenosis was defined as stenosis of 75% or greater on coronary arteriogram. Left ventricular wall motion was assessed as either normokinesis, hypokinesis, severe hypokinesis, akinesis or dyskinesis on left ventriculogram. When discordance was considered to be a marker of ischemia, the sensitivity and specificity in effort angina and control subjects were 95.2% and 84.6% for patients and 83.9% and 94.4% for diseased vessels, respectively. There were no differences between the sensitivity and specificity in left anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) lesions (83.3%, 95.5% in LAD, 83.3%, 95.5% in LCx, 85.7%, 92.6% in RCA, respectively). All of the patients with old myocardial infarction had reduced exercise BMIPP uptake in infarcted regions. In old myocardial infarction, 35 patients had segments with discordant uptake. Discordance was observed in 75 (91.5%) of 82 segments with hypokinesis, and in 24 (92.3%) of 26 segments with severe hypokinesis. Even among the 36 segments with akinesis or dyskinesis, 25 (69.0%) had discordant uptake. When discordance in the infarcted region was considered to be a marker of viability, regions with severe asynergy showed a high possibility of viability. Thus, discordant uptake on exercise BMIPP and resting T1 delayed SPECT may be a useful marker of ischemia in effort angina and of viability in old myocardial infarction.

Aged↗
PubMed1996

[Left ventricular pseudoaneurysm recognized 9 years after mitral valve replacement and repeated heart failure of 3 years duration: a case report].

A 66-year-old woman had suffered from repeated heart failure beginning 6 years after mitral valve replacement. Left ventricular pseudoaneurysm was discovered 9 years after the replacement, while no evidence including histology was obtained for the cause of the pseudoaneurysm except the mitral valve replacement. The progression of aortic valve stenosis and the formation of the pseudoaneurysm may have contributed to the onset of congestive heart failure. Surgical treatment was successful. Although left ventricular pseudoaneurysm after mitral valve replacement is rare, careful echocardiographic examination is necessary for detecting such a complication in patients after surgery.

Aged↗
PubMed1995

Genotoxic effect of griseofulvin in somatic cells of Drosophila melanogaster.

Griseofulvin (GF), a carcinogenic spindle poison, was tested in two types of somatic-cell assays of Drosophila melanogaster, one of which detects the induction of DNA damage and the other mutation/mitotic recombination. In both assays, GF was fed to tester larvae and genetic endpoints examined after emergence. In the wing spot test, trans-heterozygous flies carrying mwh and flr3 wing-hair mutations produced both significant and dose-dependent increases in the frequency of mwh single spots over the control level but no increase of twin spots. In the DNA repair test, double-mutant larvae carrying both mei-9(a) (excision repair-defective) and mei-41(D5) (postreplication repair-defective) mutations showed hypersensitivity to killing by GF compared with their DNA repair-proficient counterparts, suggesting that GF caused potentially lethal DNA damages which were efficiently repaired by the DNA repair-proficient but not -defective larvae. These lines of evidence clearly demonstrate that GF is genotoxic in somatic cells of Drosophila. It is noted that (1) GF-fed larvae showed a developmental delay and (2) surviving adult flies had morphological abnormalities in their eyes and wings.

Animals↗
PubMed1994

Studies of neuroregulators in the brain stem of SIDS.

Some dysmaturity of neuroregulator neuronal systems may be responsible for brain stem disorders. These disorders may partly explain the mechanism of death in SIDS. The available data using microbiochemical assays, immunocytochemical techniques and autoradiographic methods seem to show anomalies of some monoaminergic and of some peptidergic systems, especially in the medulla oblongata. All these data need to be confirmed by further studies. It should be understood that one positive effect of such neuroanatomical study on SIDS is to gain 'normative' data on the human brain during development.

Brain Stem↗
PubMed1992

Computer-aided interpretation of coronary cineangiograms. Accuracy of automatic detection of stenotic lesions.

To accurately diagnose stenotic lesions on coronary cineangiograms, an automatic detection method using computer image processing was developed. We evaluated its accuracy by comparing the results of computer-aided interpretation (CAI) with those obtained independently by 3 observers. Evaluation was performed on 129 segments from 27 arteries visualized on angiograms obtained in 18 patients. The detection rates of stenosis of the 3 observers by pure visual interpretation were 7.0%, 27.9%, and 17.1%, and using CAI 40.0%, 42.6%, and 47.3%. By computer recognition alone, a detection rate of 51.9% was achieved. The agreement by at least 2 observers (consensus) on the sites with lesions was 41.1% while the consensus of computer recognition regarding the sites with lesion was 40.3%. Therefore, our findings indicated that computer recognition of cineangiograms is likely to result in overdetection of lesions. However, all 3 observers detected stenotic lesions better with CAI than with pure visual interpretation. Accordingly, CAI may improve the reliability of cineangiographic diagnosis.

Arterial Occlusive Diseases↗
PubMed1990

[Contractile properties of coronary artery bypass conduit--comparison between saphenous vein and internal mammary artery].

This study was designed to examine the response of coronary artery bypass conduit to serotonin, phenylephrine, and ergonovine as provocation agents of vasoconstriction. Saphenous veins (SV) and internal mammary arteries (IMA) were obtained during coronary artery bypass grafting (CABG), and their contractile properties were measured using isometric contraction recording apparatus. Both SV and IMA showed sigmoid contraction curves indicating dose dependence to ergonovine, serotonin, and phenylephrine. The concentration-response relations for phenylephrine showed a similar curve in both SV and IMA, however, those for ergonovine and serotonin showed a leftward shift in SV compared with IMA. Half maximum effective dose for ergonovine and serotonin were less in SV than IMA. From these results, it was suggested that "perioperative spasm" during CABG might occur not only in coronary arteries but also in the graft conduit itself. Graft spasm might be a possible mechanism for occlusion of the bypass graft. In conclusion, greater hyperreactivity of SV compared with IMA in response to ergonovine and serotonin was suggested, so it is concluded that, from this point of view, IMA is more suitable for use in CABG.

Coronary Artery Bypass↗
PubMed1989

Role of serotonin, histamine, and thromboxane A2 in platelet-induced contractions of coronary arteries and aortae from rabbits.

The present study was undertaken to clarify the underlying mechanisms responsible for contractions of isolated coronary arteries and aortae from rabbits in response to thrombin-stimulated autologous platelets. Thrombin-stimulated platelets evoked potent contractions of both arteries in a platelet concentration-related manner. Pretreatment of platelets with aspirin, which almost completely inhibited thromboxane A2 synthesis but not the release reaction of biologic monoamines from platelets, caused only slight suppression of platelet-induced contractions of both arteries. Ketanserin as well as methysergide markedly inhibited aortic contractions to platelets. In contrast, the contractile responses of coronary arteries to platelets were suppressed by methysergide but not by ketanserin. Pretreatment of the arteries with diphenhydramine did not inhibit the aortic responses to platelets, but significantly suppressed coronary arterial contractions induced by higher concentrations of platelets. Phentolamine had no inhibitory effects on the responses of either artery to platelets. Pretreatment of arteries with aspirin did not affect the contractile responses of either artery to platelets. The contractile responses of aortae to exogenously administered serotonin were competitively antagonized by ketanserin, but those of coronary arteries were not. Coronary contractions to serotonin were competitively inhibited by methiothepin and significantly suppressed by methysergide. The contractile responses of both arteries to histamine were antagonized by diphenhydramine but not by cimetidine. On the basis of our results obtained from studies in organ chamber, we conclude that a major role of thromboxane A2 was not demonstrated in platelet-induced contractions of the arteries, and that those of aortae were mainly mediated by platelet-derived serotonin at S2 receptor and those of coronary arteries at S1-like receptor. The contractions of coronary arteries in responses to higher concentrations of platelets were partly mediated by histamine at H1 receptor.

Animals↗
PubMed1988

Analysis of the rat interpeduncular subnuclei by immunocytochemical double-staining for enkephalin and substance P, with some reference to the coexistence of both peptides.

The rat interpeduncular nucleus (IPN) was immunocytochemically double-stained for enkephalin (ENK) and substance P (SP) on the same sections. On the basis of both peptidergic distribution patterns and topographic relationship, the IPN was divided into nine subnuclei and one cap: the rostral subnucleus (IP-R), the central subnucleus (IP-C), the rostral-lateral subnucleus (IP-RL), the main lateral subnucleus (IP-L), the caudal-lateral subnucleus (IP-CL), the dorsal-lateral subnucleus (IP-DL), the dorsal-medial subnucleus (IP-DM), the apical subnucleus (IP-A), the intermediate subnucleus (IP-I), and the dorsal cap (IP-Cap). As the descriptions of the IP-RL, IP-L, and IP-CL were inconsistent with previous reports, they were reevaluated; the IP-RL was proposed as the region situated in the lateral portion at rostral levels and characterized by the lack of ENK and SP immunoreactive structures, the IP-L as the region situated throughout the rostrocaudal extent in the lateral portion of the IPN and containing the highest density of SP immunoreactive fibers but no ENK immunoreactive fibers, and the IP-CL as the region situated just laterocaudal to the IP-L in the caudal pole of the IPN and containing ENK immunoreactive cells and fibers but no SP immunoreactive structures. Our results also showed that some cells in the IP-R have both ENK and SP immunoreactivity. This coexistence was observed in some small spherical cells of the IP-R, but rarely in larger oval-shaped cells, which occasionally showed only ENK immunoreactivity. In addition, paired ENK immunoreactive fiber bundles entering the IP-R were found to run just rostral to the paired SP immunoreactive columns, both of which composed parts of the interpedunculotegmental tract. A three-dimensional model representing the subnuclear organization of the IPN was proposed on the basis of the present results.

Brain Mapping↗