Keishiro Kawamura

Osaka Medical College, Takatuki, Ōsaka, Japan

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Publications (29)34.78 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by the progressive replacement of myocardial cells by fat and fibrous tissue. Here we describe the histopathological features of biopsied myocardium from a patient with ARVC. A large amount of adipose tissue was present in the biopsy specimen, and a group of myocardial cells were isolated as an island-like region in the adipose tissue. Electron microscopic examination of cardiomyocytes revealed a large number of intracellular lipid droplets, including some extremely large droplets. Disruptions of the plasma membrane and dissociation of intercellular junctions were associated with discharge of intracellular lipid droplets into the interstitial space. The high accumulation of intracellular lipid droplets may be involved in the pathogenesis of ARVC and may have played an important role in myocardial cell death and progressive replacement of cardiomyocytes by fatty tissue in the current case.
    Heart and Vessels 12/2008; 23(6):440-4. · 2.13 Impact Factor
  • Japanese Circulation Journal-english Edition - JPN CIRC J. 01/2001; 65(7):691-694.
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    ABSTRACT: Scanning electron microscopy (SEM) with secondary electron emissions is useful for the study of cardiomyocyte architecture, however, the information is limited from the cell surface. Whereas backscattered electron (BSE) emission can give a high-resolution image of the specimen's intracellular structure after heavy metal staining. In this study, we applied BSE imaging analysis to the study of the arrangement of cardiomyocytes in the myocardium. The tissue specimens from a normal fresh monkey heart, normal human heart obtained at autopsy, and surgically resected tissue from a patient with old myocardial infarction in the left ventricular aneurysmectomy were used. The tissue specimens were fixed in neutral formalin, treated with NaOH and then stained with Gomori's silver methenamine reagent followed by tannic acid and osmium tetroxide. After dehydration and drying, the specimens were coated with carbon and examined by SEM with a BSE detector. In the tissue preparations, the A bands of sarcomeres were selectively stained with silver so that the arrangements of subsarcolemmal myofibrils and the intercalated discs were clearly seen in the BSE images. In the left ventricular aneurysmal walls of old myocardial infarction, atrophied cardiomyocytes with disarray of subsarcolemmal myofibrils were observed. The results strongly suggest that BSE images are further applicable to the study of the architecture of cardiac myocytes and their branches, and the arrangement of intracellular myofibrils in various diseased myocardium.
    Cardiovascular Pathology - CARDIOVASC PATHOL. 01/2000; 9(2):103-109.
  • Journal of Cardiac Failure - J CARD FAIL. 01/1999; 5(3):62-62.
  • Journal of Cardiac Failure - J CARD FAIL. 01/1999; 5(3):77-77.
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    ABSTRACT:  DBA/2 inbred mice spontaneously develop myocarditis and a unique form of subepicardial inflammation of the right ventricle characterized by a prominent eosinophilic infiltrate with calcinosis. We studied this myocarditis using light microscopy and both transmission and analytical X-ray electron microscopy, paying particular attention to eosinophil-associated cardiocyte injury. At 5 weeks of age, many eosinophils and mononuclear cells (MNCs) were seen in the subepicardium of the right ventricle. Electron microscopy showed that cardiocytes underwent degenerative changes, including myofibrillar lysis, accumulation of Z-band material and mitochondrial inclusions, and rupture of plasma membranes. The infiltrating eosinophils appeared to be activated, and cells with cytoplasmic vacuoles, suggestive of degranulation, were noted. The myocardial injury was most severe in the 7th week and healed with myocardial fibrosis and calcinosis by the 8th week. Analytical X-ray electron microscopy showed that the calcinosis was initiated in mitochondrial inclusions of injured cardiocytes. The peripheral eosinophil count did not increase during the course of the disease, but there was a positive correlation between the ratio of eosinophils to infiltrated white blood cells (Eo/WBCs) in the right ventricle and the severity of myocardial damage. Eosinophils may play a significant part in subepicardial cardiocyte injury seen in DBA/2 mice.
    Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 04/1998; 432(5):461-468. · 2.68 Impact Factor
  • Japanese Circulation Journal-english Edition - JPN CIRC J. 01/1998; 62(8):621-622.
  • Journal of Cardiac Failure - J CARD FAIL. 01/1998; 4(3):111-111.
  • Journal of Cardiac Failure - J CARD FAIL. 01/1998; 4(3):76-76.
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    ABSTRACT: We compared the diagnostic utility of serum concentrations of human heart-type cytoplasmic fatty acid-binding protein (H-FABPc), myoglobin, and their ratio for the early diagnosis of acute myocardial infarction (AMI) in 104 healthy volunteers and 165 patients at admission within 6 h of the onset of chest pain. The ROC curves of the H-FABPc [0.946, 95% confidence interval (CI) = 0.913-0.979] and myoglobin (0.895, 95% CI = 0.846-0.944) between patients with AMI and healthy volunteers were significantly greater than the area under the ratio of myoglobin to H-FABPc (0.823, 95% CI = 0.765-0.881). In 165 patients, the sensitivity (81.8%, 95% CI = 74.2-89.4%), specificity (86.4%, 95% CI = 78.1-94.6%), and predictive accuracy (83.6%, 95% CI = 78.0-89.3%) of H-FABPc > 12 micrograms/L in diagnosing AMI were significantly higher than those of myoglobin, and were similar to those of the combination of H-FABPc > 12 micrograms/L and the ratio < or = 14. We conclude that H-FABPc is a more sensitive and specific marker than myoglobin for the early diagnosis of AMI, and that their ratio cannot give a clear advantage over the measurement of H-FABPc alone.
    Clinical Chemistry 08/1997; 43(8 Pt 1):1372-8. · 7.15 Impact Factor
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    ABSTRACT: Both human heart-type cytoplasmic fatty acid-binding protein (H-FABPc) and myoglobin are low molecular weight proteins that are abundant in the cytoplasm of myocardial cells. Unlike myoglobin, H-FABPc content in the skeletal muscle is less than in cardiac muscle. To investigate the usefulness of the serum concentration of H-FABPc in the early detection of successful coronary reperfusion, we measured serum concentrations of H-FABPc and myoglobin in 45 patients with acute myocardial infarction treated with intracoronary thrombolysis or direct percutaneous transluminal coronary angioplasty. Coronary angiography was performed every 5 min for reperfusion therapy to identify the onset of reperfusion. Reperfusion, defined as a TIMI grade 2 or 3, was achieved within 60 min of the initiation of reperfusion therapy in 30 patients (the reperfused group), but was not achieved in 15 patients (the non-reperfused group). Blood samples were obtained before initiation of treatment and 15, 30 and 60 min after initiation of treatment in the non-reperfused group. In the reperfused group, samples were obtained before reperfusion and 15, 30 and 60 min after reperfusion. The H-FABPc ratio (the ratio of value after to value before the initiation of treatment or reperfusion) increased sharply after the onset of reperfusion, peaking at 41 +/- 18 min, and decreased rapidly thereafter. The predictive accuracy of an H-FABPc ratio of > 1.8 for the detection of reperfusion within 60 min of the initiation of treatment was 93% at 15 min after reperfusion, 98% at 30 min, and 100% at 60 min. Similar rates of predictive accuracy were observed for a myoglobin ratio > 2.4. The H-FABPc ratio detected successful reperfusion as early as 15 min after the onset of reperfusion and was highly accurate in detecting reperfusion within 60 min of the onset of reperfusion. The predictive accuracy of the H-FABPc ratio was similar to that of the myoglobin ratio for the early detection of successful coronary reperfusion.
    Clinica Chimica Acta 07/1997; 262(1-2):13-27. · 2.85 Impact Factor
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    ABSTRACT: Objective: To investigate the clinical significance of the QRST isointegral map in patients with dilated cardiomyopathy (DCM).Methods: We performed body surface mapping, signal-averaged ECG, and 201TI myocardial imaging in 41 patients with DCM. Using the QRST I-sub map, we derived the two parameters of the number of lead points below −2 standards of deviation for the normal nSub value and the absolute value of the Dimin.Results: LPs were detected in 17 patients (41%). The QRST I-sub map disclosed an abnormal negative area in most of the 41 patients. Both nSub and Dlmin values were larger in the group with LP than in the other group (P < 0.01). Significant inverse correlation was detected between the root mean square voltage in the last 40 ms (index of LP) and the Dlmin value (r =−0.435, P < 0.001). The abnormal scintigraphic patterns were classified into three groups with decreased uptake in the anteroseptal, inferoapical, and postero-lateral regions, the localizations of which were well-matched to the minimal points on the QRST I-sub map (F-G 4, G-H 2, and I-J 3–4, respectively). There was also a close correlation between the myocardial perfusion abnormalities and the distribution of the −2SD area on the QRST I-sub map.Conclusion: The QRST isointegral map is useful in detecting the extent and localization of the myocardial damage in patients with DCM.
    Annals of Noninvasive Electrocardiology 07/1997; 2(3). · 1.08 Impact Factor
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    ABSTRACT: Ultrastructural changes of a biopsied myocardium were observed by transmission electron microscopy in a patient with cardiomyopathy secondary to systemic triglyceride storage disease with Jordans' anomaly. There were many lipid droplets in the cardiocytes, and lipofuscin and mitochondria were increased. The volume fraction of myofibrils in the cardiocytes decreased because of an abundance of lipid droplets and mitochondriosis. Myocardial contractility may have been reduced by myofibrillar scarcity and low energy production resulting from an abnormality in the metabolism of fatty acids in the cardiocytes.
    Medical Electron Microscopy 05/1997; 30(2):88-91.
  • Japanese Circulation Journal-english Edition - JPN CIRC J. 01/1997; 61(5):367-374.
  • Japanese Circulation Journal-english Edition - JPN CIRC J. 01/1997; 61(8):724-725.
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    ABSTRACT: To identify the clinical significance of the isointegral body surface map of the QRST interval (QRST map) and the occurrence of repolarization abnormalities in patients with hypertrophic cardiomyopathy (HCM), the QRST map and signal-averaged electrocardiogram were evaluated in 50 patients with HCM, in 33 of whom the results were compared with nuclear images both for radioiodine-labeled fatty acid metabolism and for radiothallium perfusion. The QRST departure map was used to determine two parameters of difference between patient and control recordings: the subnormal area (the number of lead points at which the departure index values were negative and lay more than 2 SDs from the mean of the normal control group) and the subnormal minimum (the absolute value of the minimum in the departure map). Late potentials were detected in 6 (12%) of the 50 patients; they were observed in 3 of the 5 patients with dilated-phase HCM but in only 3 (7%) of the other 45 patients. The subnormal area and minimum values were lower in nonobstructive HCM than in dilated-phase HCM. Of the 33 patients examined by myocardial imaging, 28 (33%) had a filling defect or decreased uptake, as shown on fatty acid metabolic images, and 10 of the 28 also showed abnormal myocardial perfusion images, while the 18 others showed normal perfusion images. These 28 patients showed significantly larger values of the subnormal area and minimum than patients with normal results in both image tests, regardless of whether or not myocardial perfusion imaging abnormalities were present. The localization of filling defects or of decreased uptake presented in fatty acid metabolic images corresponded to the position of the minimum on the QRST departure map. These results suggest that the QRST map is useful for detection of repolarization abnormalities in HCM and that these abnormalities are highly related to impaired fatty acid utilization of the myocardium.
    Journal of Electrocardiology - J ELECTROCARDIOL. 01/1997; 30(1):21-29.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Both human heart-type cytoplasmic fatty acid-binding protein (H-FABPc) and myoglobin are low molecular weight proteins that are abundant in the cytoplasm of myocardial cells. Unlike myoglobin, H-FABPc content in the skeletal muscle is less than in cardiac muscle. To investigate the usefulness of the serum concentration of H-FABPc in the early detection of successful coronary reperfusion, we measured serum concentrations of H-FABPc and myoglobin in 45 patients with acute myocardial infarction treated with intracoronary thrombolysis or direct percutaneous transluminal coronary angioplasty. Coronary angiography was performed every 5 min for reperfusion therapy to identify the onset of reperfusion. Reperfusion, defined as a TIMI grade 2 or 3, was achieved within 60 min of the initiation of reperfusion therapy in 30 patients (the reperfused group), but was not achieved in 15 patients (the non-reperfused group). Blood samples were obtained before initiation of treatment and 15, 30 and 60 min after initiation of treatment in the non-reperfused group. In the reperfused group, samples were obtained before reperfusion and 15, 30 and 60 min after reperfusion. The H-FABPc ratio (the ratio of value after to value before the initiation of treatment or reperfusion) increased sharply after the onset of reperfusion, peaking at 41±18 min, and decreased rapidly thereafter. The predictive accuracy of an H-FABPc ratio of > 1.8 for the detection of reperfusion within 60 min of the initiation of treatment was 93% at 15 min after reperfusion, 98% at 30 min, and 100% at 60 min. Similar rates of predictive accuracy were observed for a myoglobin ratio > 2.4. The H-FABPc ratio detected successful reperfusion as early as 15 min after the onset of reperfusion and was highly accurate in detecting reperfusion within 60 min of the onset of reperfusion. The predictive accuracy of the H-FABPc ratio was similar to that of the myoglobin ratio for the early detection of successful coronary reperfusion.
    Clinica Chimica Acta. 01/1997;
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    ABSTRACT: Abnormal long-chain fatty acid metabolism has been suggested as having a role in the genesis of certain cardiac diseases, and depressed myocardial long-chain fatty acid uptake has been clinically demonstrated in some patients with hypertrophic cardiomyopathy. However, the site where long-chain fatty acid metabolism is affected in cardiomyopathy remains unclear. Although cardiac hypertrophy is reported to be induced in rats by a fat-free diet, little is known of the consequences of depressed myocardial long-chain fatty acid uptake. Sulfo-N-succinimidyl derivatives of long-chain fatty acids have been shown to irreversibly inhibit long-chain fatty acid transport. To investigate the possible linkage of abnormal long-chain fatty acid uptake with cardiac hypertrophy, myocardial long-chain fatty acid uptake was blocked in rats using a sulfo-N-succinimidyl derivative of palmitate (SSP).SSP was intraperitoneally administered to rats for 12 weeks, and its effects on physiological parameters, and cardiac morphology were studied. SSP treatment (20 mg/kg) caused a 12% increase in heart weight (663.7±33.6 mg in controls v 741.2±26.5 mg after SSP treatment) and an 11% increase in the heart weight to body weight ratio (2.46±0.10 in controls v 2.72±0.17 after SSP) without any significant change of body weight. No significant differences were observed in blood pressure, heart rate, and serum hormones (insulin and triiodothyronine) between the control and SSP-treated groups. An increase of the serum glucose level (1.25±0.17 g/l in controls v 1.90±0.10 g/l after SSP) and a decrease of serum non-esterified fatty acids (5.69±0.59 mm in controls v 4.00±0.38 mm after SSP) and triglycerides (97.5±13.0 mg/l in controls v 82.5±13.0 mg/l after SSP) were also observed. Light microscopy demonstrated that the transverse diameter of the myocardial cells was increased by SSP administration (14.83±0.41 μm in controls v 18.31±0.65 μm after SSP), although their morphology was not otherwise altered.The cardiac hypertrophy provoked by SSP, which depresses myocardial long-chain fatty acid uptake, seems to be associated with metabolic changes in the absence of any significant hemodynamic or hormonal effects. Some types of cardiac hypertrophy may be related to altered myocardial long-chain fatty acid uptake.
    Journal of Molecular and Cellular Cardiology 09/1995; · 5.15 Impact Factor
  • Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/1995; 25(2).
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    ABSTRACT: In this electron microscopic study of cardiocytes during regression of left ventricular hypertrophy (LVH) in spontaneously hypertensive rats (SHR), nifedipine (SHR-N) and lisinopril (SHR-L) were given to 15-week-old SHR (SHR-C15) for 20 weeks. In untreated SHR, cardiocytes were enlarged, lateral branches (LBs) multiplied and intracellular organelles became degenerated between 15 and 35 weeks of age. In SHR-N, despite a slight reduction in blood pressure (BP), LVH regressed and cell width and the number of LBs were preserved at the level found in SHR-C15. In SHR-L, LVH regressed with moderate suppression of BP; cell width, cell length and the number of LBs reverted to those in agematched Wistar Kyoto rats. In both SHR-N and SHR-L, intracellular ultrastructures were nearly normalized. These findings suggest that, in addition to BP reduction, other pharmacological factors play a role in structural repair of hypertrophied cardiocytes.
    Medical Electron Microscopy 11/1994; 27(3):239-242.

Publication Stats

146 Citations
34.78 Total Impact Points

Institutions

  • 1985–2008
    • Osaka Medical College
      • • First Department of Internal Medicine
      • • Third Department of Internal Medicine
      Takatuki, Ōsaka, Japan
  • 1997
    • Fujita Health University
      • Department of Internal Medicine
      Nagoya, Aichi, Japan