藤田 英雄

Background: Patients with diabetic retinopathy (DR) have an increased risk of death from coronary heart disease and myocardial infarction. The purpose of this study was to compare the outcomes of revascularization strategies (sirolimus-eluting stent [SES] and coronary artery bypass surgery [CABG]) in patients with DR according to the stage of retinopathy: non-proliferative retinopathy (NPDR) and proliferative retinopathy (PDR). Methods: From April 2004 until February 2007, 627 patients including 51 NPDR and 62 PDR patients underwent SES implantation. For each retinopathy group, a historical comparison group at the same stages of retinopathy undergoing CABG was selected. Cardiac events were defined as a composite of cardiac death, myocardial infarction, and repeat revascularization. Results: The average follow-up from the time of the initial revascularization was 27.7 +/- 8.5 months for NPDR-SES patients, 69.6 +/- 36.6 months for NPDR-CABG patients, 26.4 +/- 9.7 months for PDR-SES patients, and 68.3 +/- 44.2 months for PDR-CABG patients; and Kaplan-Meier estimates of the percentages of events at 24 months were 47.0%, 22.8%, 28.5%, and 26.0%. Kaplan-Meier curves for cardiac events differed significantly between the SES group and the CABG group in NPDR patients (p = 0.04), whereas the curves did not differ significantly between the two groups of PDR patients. The adjusted hazard ratio of SES implantation for cardiac events in the entire group of DR patients was 1.75 (95% confidence interval [CI] 1.02-3.00, p = 0.04). Conclusions: SES implantation is not a suitable method of revascularization in DR patients, especially in NPDR patients. CABG may become the first-choice revascularization technique for these patients. (c) 2008 Japanese College of Cardiology. Published by Elsevier Ireland Ltd. All rights reserved.

Background. We compared the 1-year outcome of coronary revascularization with sirolimus-eluting stents (SESs) or coronary artery bypass grafting (CABG) for coronary artery disease involving the left anterior descending artery (LAD) in diabetic patients according to their retinal status: no diabetic retinopathy (NDR) and diabetic retinopathy (DR). Methods. Between April 2004 and October 2005, 220 consecutive patients with coronary artery disease involving the LAD underwent implantation of SESs; of these, 25 patients had NDR and 54 had DR. For each group, we included a comparison group of diabetic patients who had undergone CABG and had the same retinal status. Results. During 1 year after revascularization, five cardiac events (cardiac death, myocardial infarction, and repeat revascularization) were noted in NDR-SES patients, four in NDR-CABG, 24 in DR-SES, and eight in DR-CABG patients. Most cardiac events were repeat revascularizations. Kaplan-Meier estimates of the incidence of cardiac events at 1 year were 21.1%, 11.4%, 44.0%, and 14.0%, respectively. Kaplan-Meier curves for cardiac events in SES patients were different from those of CABG patients for the DR group (p = 0.003), but not NDR groups. After adjustments for the potential confounders, the hazard ratio of cardiac events in DR-SES patients was 2.8 (95% confidence interval, 1.1 to 6.9; p = 0.02). Conclusions. Compared with SES implantation, CABG is more suitable for revascularization in patients with coronary artery disease involving the LAD and DR.

OBJECTIVE - The expansion of adipose tissue mass seen in obesity involves both hyperplasia and hypertrophy of adipocytes. However, little is known about how adipocytes, adipocyte precursors, blood vessels, and stromal cells interact with one another to achieve adipogenesis. RESEARCH DESIGN AND METHODS - We have developed a confocal microscopy-based method of three-dimensional visualization of intact living adipose tissue that enabled us to simultaneously evaluate angiogenesis and adipogenesis in db/db mice. RESULTS - We found that adipocyte differentiation takes place within cell clusters (which we designated adipogenic/angiogenic cell clusters) that contain multiple cell types, including endothelial cells and stromal cells that express CD34 and CD68 and bind lectin. There were close spatial and temporal interrelationships between blood vessel formation and adipogenesis, and the sprouting of new blood vessels from preexisting vasculature was coupled to adipocyte differentiation. CD34 + CD68+ lectin-binding cells could clearly be distinguished from CD34- CD68+ macrophages, which were scattered in the stroma and did not bind lectin. Adipogenic/angiogenic cell clusters can morphologically and immunohistochemically be distinguished from crownlike structures frequently seen in the late stages of adipose tissue obesity. Administration of anti-vascular endothelial growth factor (VEGF) antibodies inhibited not only angiogenesis but also the formation of adipogenic/angiogenic cell clusters, indicating that the coupling of adipogenesis and angiogenesis is essential for differentiation of adipocytes in obesity and that VEGF is a key mediator of that process. CONCLUSIONS - Living tissue imaging techniques provide novel evidence of the dynamic interactions between differentiating adipocytes, stromal cells, and angiogenesis in living obese adipose tissue. © 2007 by the American Diabetes Association.

Introduction: The prognostic value of identifying the retinal status of diabetic patients undergoing coronary implantation of drug-eluting stents is unknown. Methods: We evaluated the outcomes of 318 consecutive patients undergoing implantation of sirolimus-eluting stents for coronary artery disease. Patients were divided into 5 groups according to the diabetic and retinal status: diabetic patients without retinopathy (43 patients) diabetic patients with nonproliferative retinopathy (34) diabetic patients with proliferative retinopathy (37) diabetic patients with unknown retinal status (30) and nondiabetic patients (174). Results: During a mean follow-up of 385 days, 64 patients had target-vessel failure (defined as a composite of death from cardiac causes, myocardial infarction, and target-vessel revascularization). At 1 year, Kaplan-Meier estimates of the rate of target-vessel failure were 15.3% for diabetic patients without retinopathy, 56.6% for those with nonproliferative retinopathy, 17.3% for those with proliferative retinopathy, 19.0% for those with unknown retinal status, and 16.0% for nondiabetic patients. After adjustment for the potential confounders and differences between groups, the relation of nonproliferative retinopathy to target-vessel failure remained significant. In an analysis in which diabetic patients without retinopathy were used as the reference group, the hazard ratios for target-vessel failure were 3.9 for those with nonproliferative retinopathy, 1.3 for those with proliferative retinopathy, 1.1 for those with unknown retinal status, and 1.4 for nondiabetic patients (P for trend = 0.015). Conclusions: As compared with diabetic patients without retinopathy, those with nonproliferative retinopathy have an increased risk for target-vessel failure after coronary implantation of sirolimus-eluting stents. © 2007, the Authors.

Objective: To elucidate the interdependence between the mechanical state of the myocardium and its electrical activity, previous studies have been performed at the cellular level. However, the information to date has been limited by the technical difficulties associated with stretching single myocytes. Methods: We solved this problem by combining two techniques, namely a carbon fiber technique for stretching rat myocytes with wide ranges of amplitude and speed, and ratiometric measurement of a fluorescent indicator (di8-ANEPPS) for evaluating the membrane potential in the non-contact mode. Results: During systole, stretching caused depolarization that prolonged the action potential duration without affecting the peak amplitude, but the effect was only significant in the late phase. Application of a stretch to quiescent myocytes depolarized the membrane potential in amplitude- and speed-dependent manners, but the response was suppressed by cytochalasin D treatment, suggesting participation of the cytoskeleton in the mechanotransduction mechanism. Finally, ion replacement experiments revealed that although Na+ was the dominant charge carrier for large amplitude stretches, Ca2 + permeation was involved in small amplitude stretches, suggesting amplitude-dependent ion selectivity. Conclusions: Application of axial stretching to rat ventricular myocytes changed the membrane potential in phase-, amplitude- and speed-dependent manners. Amplitude may also modulate the ion selectivity of stretch-activated channels. © 2006 European Society of Cardiology.

Nowadays, evidence-based medicine has entered the mainstream of clinical judgement and the human genome has been completely decoded. Even the concept of individually designed medicine, that is, tailor-made medicine, is now being discussed. Due to their complexity, however, management methods for clinical information have yet to be established. We have conducted a study on a universal technique which enables one to select or produce by employing information processing technology clinical findings from various clinical information generated in vast quantity in day-to-day clinical practice, and to share such information and/or the results of analysis between two or more institutions. In this study, clinically useful findings have been successfully obtained by systematizing actual clinical information and genomic information obtained by an appropriate collecting and management method of information with due consideration to ethical issues. We report here these medical achievements as well as technological ones which will play a role in propagating such medical achievements. Copyright © 2004 by the Japanese Heart Journal.

Objective: To investigate the functional role of myosin light chain (MLC) isoforms in cardiac muscles, we examined the motor function of two different myosins the structure of which differed only in the MLC. Methods: We purified myosin from atria (A-myosin) and ventricles (V-myosin) of young rats, which contained atrial-type and ventricular-type MLCs, respectively, but having identical α-heavy chain isoform. Actin filament velocity (Vel) was determined in the in vitro motility assay. Average force of myosin molecules (F) was estimated and single events of actin-myosin interaction were recorded with the laser trap technique. Results: Vel was slightly higher in A-myosin than in V-myosin, while actin-activated ATPase activity was not different. F, determined from force versus actin filament length relation, was ∼60% higher in V-myosin (3.3 vs. 2.1 pN/μm). The mean duration of isometric force events was longer in V-myosin than in A-myosin (323±13 vs. 294±30 ms, p&lt 0.05), while the amplitudes of unitary displacement and force of a single myosin molecule did not differ between them. Conclusion: The MLC isoform can be a determinant of force-generating ability of cardiac myosin by modulating crossbridge kinetics without affecting the catalytic activity. © 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.

To facilitate cardiac muscle research, we developed a novel method by which the force and length of a single ventricular myocyte can be recorded with a pair of carbon graphite fibers attached firmly to both ends. One fiber was stiff, whereas the other fiber was compliant to allow the recording of force and shortening during twitch contractions. The image of the compliant carbon fiber was projected onto a pair of photodiodes, and their output was fed to a piezoelectric transducer after variable amplifications to alter the effective compliance of the carbon fiber. Thus contraction of the myocyte was induced under virtually isometric conditions as well as under auxotonic conditions. We obtained a bell-shaped relation between the compliance under an auxotonic load and the work output of the myocyte, which was directly related to myocyte performance in the heart. Because it is easy to attach myocytes to the experimental apparatus, the present method would allow us to study cardiac muscle mechanics at the cellular and molecular levels.

Background: Conventional vasodilators increase ventilation-perfusion mismatch and do not improve gas exchange even though they reduce pulmonary hypertension. However, the effects of nitric oxide inhalation on ventilatory and gas exchange values in patients with congestive heart failure are not known. Objective: To investigate the effect of nitric oxide inhalation on gas exchange in patients with congestive heart failure, Design: Randomized, controlled trial. Setting: University hospital. Patients: 16 patients with congestive heart failure (New York Heart Association class II or III). Interventions: Patients inhaled nitric oxide gas at graded concentrations (n = 8) or were given intravenous isosorbide dinitrate, 2.5 mg (n = 8). Measurements: Hemodynamic and ventilatory variables and blood gases were measured 5 minutes after inhalation of different doses of nitric oxide and 10 minutes after administration of isosorbide dinitrate. Results: Nitric oxide inhalation reduced the mean pulmonary arterial pressure in a dose-dependent manner without altering the mean arterial pressure or cardiac output. At a dose of 40 parts per million, nitric oxide inhalation increased PaO2 (change from baseline, 12.0 mm Hg [95% Cl, 2.3 to 21.7 mm Hg] P = 0.014) and decreased the alveolar-arterial difference in partial pressure of oxygen (change, -8.6 mm Hg [Cl, -16.8 to -0.4 mm Hg] P = 0.038) and the ventilatory equivalent for carbon dioxide output (change, -6.7 [Cl, -10.3 to -3.1] P &lt 0.001). Although isosorbide dinitrate similarly decreased pulmonary arterial pressure, it did not alter gas exchange or ventilatory variables. Conclusions: Because nitric oxide inhalation improved gas exchange, it may be used as a supportive therapy when other conventional vasodilators worsen gas exchange.

To provide information on the mechanism of cardiac adaptation at the molecular level, we compared the unitary displacements and forces between the 2 rat cardiac myosin isoforms, V1 and V3. A fluorescently labeled actin filament, with a polystyrene bead attached, was caught by an optical trap and brought close to a glass surface sparsely coated with either of the 2 isoforms, so that the actin-myosin interaction took place in the presence of a low concentration of ATP (0.5 μmol/L). Discrete displacement events were recorded with a low trap stiffness (0.03 to 0.06 pN/nm). Frequency distribution of the amplitude of the displacements consisted of 2 gaussian curves with peaks at 9 to 10 and 18 to 20 nm for both V1 and V3, suggesting that 9 to 10 nm is the unitary displacement for both isoforms. The duration of the displacement events was longer for V3 than for V1. On the other hand, discrete force transients were recorded with a high trap stiffness (2.1 pN/nm), and their amplitude showed a broad distribution with mean values between 1 and 2 pN for V1 and V3. The durations of the force transients were also longer for V3 than for V1. These results indicate that both the unitary displacements and forces are similar in amplitude but different in duration between the 2 cardiac myosin isoforms, being consistent with the reports that the tension cost is higher in muscles consisting mainly of V1 than those consisting mainly of V3.

To clarify the physiological significance of myosin isoform redistribution in cardiac adaptation process, we compared the kinetic property of the two cardiac myosin isoforms using in vitro motility assay techniques. Cardiac myosin isoforms V1 and V3 were obtained from ventricular muscle of young rats and hypothyroid rats respectively. On each of these myosin isoforms fixed on a glass coverslip, fluorescently labeled actin filaments were made to slide in the presence of ATP. To measure the force generated by actomyosin interaction, a small latex bead was attached to the barbed end of an actin filament and the bead was captured by the laser optical trap installed in a microscope. The force was determined from the distance between the bead and the trap positions under either auxotonic or isometric conditions. The time-averaged force generated by multiple cross- bridges did not differ significantly between the two isoforms. On the other hand, the unitary force measurement revealed the same level of amplitude but a longer duration for V3 isoform. The same level of time-averaged force is in agreement with not only our previous finding but the results of maximum force measurement in muscle preparations. The difference in kinetic characteristics of the two isoforms could account for the difference in economy of force development and the basis for cardiac adaptation mechanism.

Familial hypertrophic cardiomyopathy (FHC) is caused by missence mutations in β-myosin heavy chain or other various sarcomeric proteins. To elucidate the functional impact of FHC mutations in myosin heavy chain, we generated Dictyostelium discoideum myosin II mutants equivalent to human FHC mutations by site-directed mutagenesis, and characterized their molecular- basis motor function. The current mutants, i.e. R397Q, F506C, G575R, A699R, K703Q and K703W are equivalent to R403Q, F513C, G584R, G716R, R719Q and R719W FHC mutants respectively. We measured the molecular-basis force and the sliding velocity generated by these myosin mutants. The measurement revealed that the A699R, K703Q and K703W myosins exhibited the lowest level of force with their preserved actin-activated MgATPase activity. F506C mutant showed the least impairment of the motile and enzymatic activities. The motor function of R397Q and G575R myosins were classified as intermediate. These results suggest that ELC binding domain might be important for force production.

Recent studies have revealed that familial hypertrophic cardiomyopathy (FHC) is caused by missence mutations in myosin heavy chain or other sarcomeric proteins. To investigate the functional impact of FHC mutations in myosin heavy chain, mutants of Dictyostelium discoideum myosin II equivalent to human FHC mutations were generated by site-directed mutagenesis, and their motor function was characterized at the molecular level. These mutants, i.e., R397Q, F506C, G575R, A699R, K703Q, and K703W are respectively equivalent to R403Q, F513C, G584R, G716R, R719Q, and R719W FHC mutants. We measured the force generated by these myosin mutants as well as the sliding velocity and the actin-activated ATPase activity. These measurements showed that the A699R, K703Q, and K703W myosins exhibited unexpectedly weak affinity with actin and the lowest level of force, though their ATPase activity remained rather high. F506C mutant which has been reported to have benign prognosis exhibited the least impairment of the motile and enzymatic activities. The motor functions of R397Q and G575R myosins were classified as intermediate. These results suggest that the force level of mutant myosin molecule may be one of the key factors for pathogenesis which affect the prognosis of human FHC.

Distinct crossbridge kinetics among cardiac myosin isoforms have been proposed as the basis of differences in energetic characteristics. However, direct evidence for this hypothesis is lacking because of experimental difficulty. As a preliminary approach to this problem, we applied an in-vitro force measurement technique to directly observe force impulse generated by a single cardiac myosin molecule. The force measurement system was constructed with an inverted microscope coupled with a laser optical trap. With the feedback of the position signal to the driving circuit for a galvanomirror that steers the laser beam, trap stiffness was increased thus, isometric force measurement was made possible. We measured the force generated by the cardiac myosin V3 isoform purified from hypothyroid rat ventricular muscle. With very low myosin density and low adenosine triphosphate (ATP) concentration of the assay buffer, we successfully observed a single force impulse similar in shape to that of skeletal muscle myosin. With this approach, we will be able to gain a clear view of the molecular basis of cardiac mechanoenergetics.

MCI-154 (6-[4-(4′-pyridylamino)phenyl]-4,5-dihydro-3(2H)pyridazinone hydrochloride trihydrate) is a potent novel cardiotonic agent whose positive inotropism is shown to be mainly based on an increase in Ca2+ sensitivity of the contractile apparatus. To elucidate the exact mechanism through which this drug acts, we investigated the movement of the reconstituted thin filament on a myosin layer in vitro. Cardiac thin filaments were reconstituted from actin and tropomyosin-troponin complex purified from rat cardiac acetone powder separately. Double staining of the filament showed that tropomyosin-troponin complex was integrated along actin filament homogeneously. Thin filaments thus prepared were fluorescently labeled and made to slide on rat cardiac myosin fixed on a glass coverslip while varying the [Ca2+] of the medium (control, pH 7.2 at 25°C). When [Ca2+] was low, the filaments showed only brownian motion. However, above a certain level of [Ca2+] (the threshold [Ca2+]), the filaments started to slide, and the velocity increased, reaching the maximum velocity within a very narrow range of [Ca2+]. The regulation was completely abolished by using simple actin filaments without tropomyosin-troponin complex, demonstrating that the regulatory proteins are responsible for this Ca2+ regulation of the movement of the reconstituted thin filament. Under the control condition, addition of MCI-154 shifted the threshold [Ca2+] to a lower level (sensitization) in a concentration-related manner. And 10-4 mol/L of MCI-154 reversed the desensitization effect induced by either acidosis (pH 6.8), low temperature (15°C), or the addition of inorganic phosphate (10 mmol/L). However, the maximum sliding velocity was not affected by the drug under any condition. In conclusion, MCI-154 directly sensitized the contractile apparatus under not only physiological but also pathophysiological conditions. This in vitro motility assay technique using reconstituted thin filaments is a useful tool for studying the mechanism of action of Ca2+ sensitizers.

We attempted to introduce calcium regulation into in vitro motility assay. Cardiac thin filament was reconstituted from actin and tropomyosin-troponin complex purified from rat myocardium separately. Double staining of the filaments showed tropomyosin-troponin complex was integrated along actin filaments homogeneously. The reconstituted thin filaments were made to slide on cardiac myosin fixed on a glass coverslip in the presence of MgATP while varying free Ca2+ concentration of the medium ([Ca2+]). Filaments showed only Brownian motion when [Ca2+] was below 10-6.4 M. However, filaments slid at a constant velocity when [Ca2+] exceeded 10-6.4 M, showing that the sliding was regulated in an on-off manner. The threshold [Ca2+] increased to 10-5.0 M under acidic conditions, indicating a decrease in Ca2+ sensitivity of the contractile proteins. Simple actin filaments slid at a constant velocity independently of [Ca2+], demonstrating that the regulatory proteins were responsible for this on-off manner regulation. This new assay technique may be a powerful tool to directly evaluate the Ca2+ sensitivity of the contractile apparatus and to investigate how cardiac contraction is regulated by Ca2+. © 1995 Springer-Verlag.

1) TECは先端のカッターを回転させて粥腫を破砕し,破砕片を吸引回収する新しいカテーテルである。TECを用いた冠動脈形成術において,末梢塞栓を認めず,血栓除去効果は十分期待できる。2) TEC通過成功病変は21病変中8病変,TECのみで残存狭窄度50%以下となった病変は12病変であり,TECのみでは,粥腫除去効果は不十分である。3)バックアップの弱い9Fのガイドカテーテルとハイトルクフロッピーガイドワイヤーを使用した症例に,TEC通過不成功例があり,病変部のTEC通過にはガイドカテーテルの強い補助と専用ガイドワイヤーの使用が必要と考えられた。4)極端な屈曲を有する病変を除外することによりTECは比較的安全に施行し得た。5) TECとバルーンを使用した冠動脈形成術の3ヵ月後の再狭窄率は29%であった。翌日造影時の狭窄度は,3ヵ月後再狭窄のpredictorであった