[en] The aims of this study were to develop a method for quantitative estimation of the myocardial blood flow index (MBFI) and myocardial flow reserve (MFR) of the whole left ventricle using ^99mtechnetium (Tc-99m)-sestamibi imaging. Twenty-two patients with suspected coronary artery disease and 7 controls underwent both Tc-99m-sestamibi imaging and O-15 water positron emission tomography (PET). The global MBFI was calculated on the basis of the microsphere model from the ratio of the myocardial count to the area under the time-activity curve on the aortic arch. The regional MBFI was calculated from the relative distributions of Tc-99m-sestamibi uptake values. The regional MBFI and MFR (Tc-MFR) obtained using single-photon emission computed tomography were compared with the myocardial blood flow (MBF) and MFR (PET-MFR) obtained using PET as the gold standard. Regional MBFI significantly correlated with the MBF obtained using PET. Regional Tc-MFR also correlated with the regional PET-MER, with some underestimation. These results indicate that regional MBF and MFR may be estimated by dynamic Tc-99m-sestamibi imaging and can be used for the early detection and estimation of the functional severity of coronary lesions without the need for a PET camera. (author)

[en] Elevated plasma plasminogen activator inhibitor-1 (PAI-1) is related to cardiovascular events, but its role in subclinical coronary microvascular dysfunction remains unknown. Thus, in the present study it was investigated whether elevated plasma PAI-1 activity is associated with coronary microvascular dysfunction in hypertensive patients. Thirty patients with untreated essential hypertension and 10 age-matched healthy controls were studied prospectively. Myocardial blood flow (MBF) was measured by using ¹⁵O-water positron emission tomography. Clinical variables associated with atherosclerosis (low-density lipoprotein-cholesterol, high-density lipoprotein (HDL)-cholesterol, triglyceride, homeostasis model assessment (HOMA-IR), and PAI-1 activity) were assessed to determine their involvement in coronary microvascular dysfunction. Adenosine triphosphate (ATP)-induced hyperemic MBF and coronary flow reserve (CFR) were significantly lower in hypertensive patients than in healthy controls (ATP-induced MBF: 2.77±0.82 vs 3.49±0.71 ml·g^-1·min^-1; p<0.02 and CFR: 2.95±1.06 vs 4.25±0.69; p<0.001). By univariate analysis, CFR was positively correlated with HDL-cholesterol (r=0.46, p<0.02), and inversely with HOMA-IR (r=-0.39, p<0.05) and PAI-1 activity (r=-0.61, p<0.001). By multivariate analysis, elevated PAI-1 activity remained a significant independent determinant of diminished CFR. Elevated plasma PAI-1 activity was independently associated with coronary microvascular dysfunction, which suggests that plasma PAI-1 activity is an important clue linking hypofibrinolysis to the development of atherosclerosis. (author)

[en] The ¹¹C-acetate positron emission tomography can estimate myocardial oxidative metabolism, but previous studies have only evaluated small populations and the difference between ischemic (ICM) and idiopathic dilated cardiomyopathy (DCM) has not been fully investigated. The present aims were to evaluate global and regional myocardial oxidative metabolism in a well-characterized, large population with left ventricular (LV) dysfunction in order to clarify the metabolic differences between ICM and DCM. Seventy-eight patients with ejection fraction (EF) ≤50% (33 ICM; 45 DCM) were compared with 14 healthy controls. Myocardial oxidative metabolism was estimated with a clearance rate constant (K_mono) and the coefficient of variation (CV) of regional K_mono. Patients with LV dysfunction had reduced K_mono and higher CV (p<0.05). In the comparison of oxidative alterations with clinical variables there was a weak correlation between K_mono and LVEF (r=0.27). Although K_mono was reduced in both ICM and DCM, CV was more pronouncedly increased in ICM (p=0.001). In multivariate analysis, the presence of left bundle branch block (LBBB) was an independent predictor of heterogeneous oxidative metabolism in DCM (R²=0.30, p<0.0001). Global reduction of myocardial oxidative metabolism occurred in both ICM and DCM. Heterogeneous oxidative metabolism was observed in these patients, especially those with ICM. Furthermore, LBBB was the independent predictor of heterogeneous oxidative metabolism in patients with DCM. (author)

[en] Myocardial flow reserve (MFR) measurement has an important role in assessing the functional severity of coronary artery stenosis. However, a discrepancy between the anatomical severity of coronary artery stenosis and MFR is often observed. Such a discrepancy may be explained by coronary risk factors. In this study, we aimed to investigate the influence of coronary artery stenosis severity and risk factors on MFR. Seventy-four patients suspected to have coronary artery disease and seven age-matched healthy volunteers were enrolled. Myocardial blood flow (MBF) and MFR were measured using ¹⁵O-labelled water PET. Regional MFR was calculated in regions with significant coronary artery stenosis (stenotic regions) and in regions without significant stenosis (remote regions). The contributions of coronary artery stenosis severity and coronary risk factors were assessed using univariate and multivariate analyses. In stenotic regions, MFR correlated inversely with coronary artery stenosis severity (r=-0.50, p<0.01). Univariate analysis did not show any significant difference in MFR between the patients with and the patients without each risk factor. In remote regions, however, MFR was significantly decreased in the diabetes and smoking groups (each p<0.05). By multivariate analysis, diabetes and smoking were independent predictors of MFR (each p<0.05). In the group with more than one risk factor, MFR was significantly lower (2.78±0.79) than in the other group (3.40±1.22, p<0.05). MFR is influenced not only by coronary stenosis severity but also by coronary risk factors. In particular, the influence of risk factors should be considered in regions without severe coronary stenosis. (orig.)

[en] The formation of Ge layers on boron-doped Si (001) substrates by our sputter epitaxy method has been investigated. The surface morphology of Ge layers grown on Si substrates depends on the substrate resistance, and flat Ge layers are obtained on Si substrates with 0.015 Ω cm resistivity. Highly boron-doped Si substrates cause a transition in the dislocation structure from complex dislocations with 60° dislocation glide planes to 90° pure-edge dislocations, resulting in the formation of flat Ge layers. Furthermore, we have found that the surface morphology of the Ge layers improves with increasing Ge layer thickness. Ge atoms migrating on the deposited Ge layers tend to position themselves at the reactive sites, where the reactivity is related to the number of bonding contacts between the Ge atom and the surface. This modifies the surface morphology, resulting in a flatter surface. Boron dopants together with the sputter epitaxy method effectively suppress the growth of Ge islands and result in the formation of flat Ge layers

[en] The mechanism of Sn surface segregation during the epitaxial growth of GeSn on Si (001) substrates was investigated by Auger electron spectroscopy and energy dispersive X-ray spectroscopy. Sn surface segregation depends on the growth temperature and Sn content of GeSn layers. During Sn surface segregation, Sn-rich nanoparticles form and move on the surface during the deposition, which results in a rough surface owing to facet formation. The Sn-rich nanoparticles moving on the surface during the deposition absorb Sn from the periphery and yield a lower Sn content, not on the surface but within the layer, because the Sn surface segregation and the GeSn deposition occur simultaneously. Sn surface segregation can occur at a lower temperature during the deposition compared with that during postannealing. This suggests that the Sn surface segregation during the deposition is strongly promoted by the migration of deposited Ge and Sn adatoms on the surface originating from the thermal effect of substrate temperature, which also suggests that limiting the migration of deposited Ge and Sn adatoms can reduce the Sn surface segregation and improve the crystallinity of GeSn layers

[en] Morphology of vicinal sapphire (1 -1 0 2) surfaces was observed in air by atomic force microscopy (AFM) after annealing at temperatures between 1073 K and 1273 K. Surfaces of one type of the samples exhibited high densities of islands and voids with single-atomic height near the step edges at the early stage of annealing, and the crystallographic anisotropy appears as their elongated shapes. During the subsequent annealing, their densities were decreased through the Ostwald ripening process, and finally they were incorporated into the upper and lower terraces. On surfaces of another type of the samples, a comb-shaped pattern consisting of parallel-striped domains running along the [1 -1 0 -1] direction appeared upon the annealing at 1273 K for 3 h. Difference in hydrophilicity was observed between the striped domains and the other areas using frictional force microscopy, which detects the amount of adsorbed water on the surface through meniscus force. The striped pattern that is one of the features of the surface anisotropy is considered to be formed because the surface energy can be decreased when two striped stress domains are alternately arranged.

[en] Long-chain fatty acid (LCFA) is the main energy source for normal myocardium at rest, but in ischemic myocardium, the main energy substrate shifts from LCFA to glucose. ¹²³I-BMIPP is a radiolabeled LCFA analog. In chronic stable angina without previous infarction, we suppose that reduced ¹²³I-BMIPP uptake is related to the substrate shift in myocardium with decreased myocardial flow reserve (MFR). The purpose of this study was to relate ¹²³I-BMIPP uptake to rest myocardial blood flow (MBF), hyperemic MBF, and MFR assessed with ¹⁵O-water positron emission tomography (PET). We enrolled 21 patients with chronic stable angina without previous infarction, all of whom underwent ¹²³I-BMIPP single-photon emission computed tomography (SPECT) and ¹⁵O-water PET. The left ventricle was divided into 13 segments. In each segment, rest MBF and hyperemic MBF were measured by PET. ¹²³I-BMIPP uptake was evaluated as follows: score 0=normal, 1=slightly decreased uptake, 2=moderately decreased uptake, 3=severely decreased uptake, and 4=complete defect. ¹²³I-BMIPP uptake was compared with rest MBF, hyperemic MBF, and MFR. The numbers of segments with ¹²³I-BMIPP scores 0, 1, 2, 3, and 4 were 178, 40, 25, 24, and 0, respectively. The rest MBFs for scores 0, 1, 2, and 3 were 0.93±0.25, 0.86±0.21, 0.97±0.30, and 0.99±0.37 ml/min/g, respectively. The hyperemic MBFs for scores 0, 1, 2, and 3 were 2.76±1.29, 1.84±0.74, 1.37±0.39, and 1.08±0.40 ml/min/g, respectively. The MFRs for scores 0, 1, 2, and 3 were 3.01±1.38, 2.20±0.95, 1.44±0.22, and 1.10±0.26, respectively. As ¹²³I-BMIPP uptake declined, hyperemic MBF and MFR decreased. In chronic stable angina without previous infarction, reduced ¹²³I-BMIPP uptake implies decreased MFR. (orig.)

[en] Several clinical studies have shown that iodine-123 labelled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) uptake is often lower than the uptake of perfusion tracers in patients with ischaemic heart disease. However, BMIPP accumulation may not decrease during the acute phase of a stunned myocardium in patients with acute coronary syndrome. We evaluated serial changes in BMIPP and perfusion tracer uptake in the myocardium after ischaemia. We performed a 20-min left coronary artery occlusion followed by reperfusion in male Wister rats. One hour after the reperfusion, echocardiography was performed. Intravenous injection of iodine-125 labelled BMIPP and thallium-201 was performed 1 day (acute group) and 5 days (subacute group) after the operation. To determine the myocardial distribution of ¹²⁵I-BMIPP and ²⁰¹Tl, dual-tracer autoradiography was conducted. We identified regions of interest in the anterolateral wall as an area at risk and in the inferoseptum as a remote control area. The anterolateral wall/inferoseptum ratio (A/I ratio) was calculated to compare the distributions of ¹²⁵I-BMIPP and ²⁰¹Tl. Coronary occlusion induced hypokinesia in the anterolateral region 1 h after the reperfusion. The A/I ratio of ¹²⁵I-BMIPP was significantly higher than that of ²⁰¹Tl in the acute group (1.01±0.15 vs 0.80±0.23, P<0.001). On the other hand, there was no significant difference between the A/I ratios of ¹²⁵I-BMIPP and ²⁰¹Tl in the subacute group (0.88±0.18 vs 0.85±0.18). Two rats showed a significantly lower A/I ratio of ¹²⁵I-BMIPP than ²⁰¹Tl in the subacute phase. These data suggest that BMIPP uptake is preserved despite a decrease in perfusion in the acute phase after ischaemia. In the subacute phase, on the other hand, BMIPP uptake is similar to or even lower than thallium uptake. Since BMIPP uptake may change with time after ischaemia, careful interpretation of BMIPP uptake after ischaemia is required in a clinical setting. (orig.)

[en] Highlights: • Lattice-matched Ge/GeSiSn layers were examined by Raman spectroscopy • Crystallinity of the Ge/GeSiSn layers improves as the Ge layers become thicker • Crystallinity depends on the ratio of the growth times of Ge and GeSiSn layers Lattice-matched Ge/GeSiSn layers were formed on Ge substrates by sputter epitaxy, and the effects of the thicknesses of the Ge and GeSiSn layers on crystallinity of the Ge/GeSiSn layers were examined by Raman spectroscopy. First, a GeSiSn layer was formed on a Ge substrate, and then a Ge layer was formed on it. Raman spectra were obtained from the formed Ge/GeSiSn layers, and crystallinity was evaluated by using the full width at half maximum (FWHM) values of the Raman peaks. The growth temperature was about 300°C. The light wavelength of the Raman spectroscope used in this study was 532 nm. A single Raman peak was observed at the Raman spectra obtained from the Ge/GeSiSn layers, which was derived from the upper Ge layers due to the penetration length. From the Raman spectra, crystallinity of the Ge/GeSiSn layers depended on the thicknesses of the Ge and GeSiSn layers. Crystallinity decreased as the GeSiSn layer became thicker and increased as the Ge layers became thicker. We found that the normalization of the FWHM values by the ratio of the film thicknesses or growth times of the Ge and GeSiSn layers can be useful for evaluating the growth conditions.