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H Sakuma

Publications and source records attributed to H Sakuma.

At least 19 recordsLinked to original sources
PubMed2006

Prognostic predictive values of serum cytochrome c, cytokines, and other laboratory measurements in acute encephalopathy with multiple organ failure.

AIMS: To evaluate the prognostic predictive values of cytochrome c, cytokines, and other laboratory measurements in serum collected during neurological onset in acute encephalopathy with multiple organ failure. METHODS: In addition to general laboratory examinations, the concentrations of cytochrome c (apoptosis marker) and cytokines (inflammatory markers) were measured in serum samples collected at the initial phase in 29 patients with acute encephalopathy. The obtained values were evaluated as predictors for the development of severe encephalopathy. RESULTS: Cytochrome c, tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), soluble TNF-receptor 1 (sTNF-R1), and aspartate aminotransferase (AST) concentrations at the initial phase were high and correlated well with patient outcome. High concentrations of serum cytochrome c (>45 ng/ml), sTNF-R1 (>2000 pg/ml), AST (>58 IU/dl), IL-6 (>60 pg/ml), and TNF-alpha (>15 pg/ml) predicted an unfavourable prognosis (sequelae and death) at 93%, 79%, 82%, 77%, and 60%, respectively. The specificity of those markers was 100%, 89%, 83%, 100%, and 100%, respectively. CONCLUSIONS: Serum cytochrome c is the most sensitive and specific predictor for the development of severe encephalopathy at the initial phase. Results suggest that this marker might be used to guide decisions regarding the start of the initial treatment and further intensive care.

Acute Disease↗
PubMed2004

Imaging of cyclotron emission from edge channels in quantum Hall conductors.

A local probing technique of cyclotron emission is applied to image nonequilibrium electrons generated along edge channels in quantum Hall conductors. In a lower-magnetic field region of a quantum Hall state plateau (filling factor 2<nu), cyclotron emission is found to occur along the boundary of a conductor on the side of lower potential (with positive Hall voltage). The emission indicates that electrons are accumulated in the first-excited Landau level, while they are depleted in the lowest Landau level along the boundary as a consequence of adiabatic-transport.

Journal Article↗
PubMed2004

Magnetic resonance measurement of coronary blood flow.

Magnetic resonance (MR) flow measurement in the coronary artery can be achieved with either a breath-hold acquisition or a respiration-triggered acquisition. MR measurements of cardiac output are significantly depressed during breath-holding at deep inspiration, but the advantage is that the breath-hold method requires less scan time. Blood flow in the coronary sinus reflects the global myocardial blood flow because it represents approximately 96% of the total myocardial blood flow of the left ventricle (LV). If blood flow in the coronary sinus is measured with phase-contrast cine magnetic resonance imaging (MRI) and LV myocardial mass is measured with cine MRI, both the total myocardial blood flow and the average coronary blood flow per gram of myocardial mass can be quantified. Coronary flow reserve with volumetric MR flow measurement is measured to be within 4.2-5.0-fold. The noninvasive MR measurement of coronary flow reserve has been shown to be useful in identifying the functional significance of stenoses in the left anterior descending artery. The sensitivity and specificity of MR coronary flow velocity reserve for identifying stenosis of 70% or greater in the left main or left anterior descending artery were 100% and 83%, respectively. The MR quantification of total coronary blood flow and coronary blood flow per gram of myocardial mass seems to be an ideal method for evaluating coronary hemodynamics and may be useful in evaluating endothelial dysfunction of the coronary circulation.

Cardiac Output↗
PubMed2003

Correlation of transthoracic Doppler echocardiography and magnetic resonance imaging in measuring left anterior descending artery flow velocity and time-course of dipyridamole-induced coronary flow increase.

There is an increasing need for new, functional and more quantitative parameters to assess coronary arterial function, for the purposes of evidence-based medicine. Coronary arterial function has been widely studied using pharmacological stimulation induced by dipyridamole or adenosine. Coronary flow reserve (CFR), defined as the ratio of pharmacologically induced hyperemic flow divided by basal flow, has been found to be an important functional index in both the clinical and subclinical stages of cardiovascular diseases. Ten healthy male volunteers were studied to compare transthoracic Doppler echocardiography (TTE) and MRI for measuring left anterior descending coronary artery (LAD) flow velocity and CFR. Additionally, the time-response curve of dipyridamole infusion was studied in five healthy males using TTE. Assessment of blood flow velocity, measured as MDV, PDV and VTI indicated Pearson's correlation coefficients of 0.88, 0.85 and 0.70, respectively, between flow velocity measurements performed using TTE and MRI. The results indicate that, despite minor differences in LAD diastolic velocities measured by TTE and MRI, the correlation of the LAD diastolic velocities measured using both methods are good and both methods are feasible for measuring CFR. Moreover, TTE has the unique capability of continuous measurement of LAD flow velocity, which allowed assessment of the time-response curve for dipyridamole-induced increase in LAD flow velocity in this study. This study indicates that the TTE method may be used in sequential or on-line monitoring of LAD blood flow velocity and therefore can be applied to evaluate the time- or dose-response effects of infused drugs in the coronary circulation of humans.

Adult↗
PubMed2001

Thermodynamics of fluid turbulence: a unified approach to the maximum transport properties.

Dissipative properties of various kinds of turbulent phenomena are investigated. Two expressions are derived for the rate of entropy increase due to thermal and viscous dissipation by turbulence, and for the rate of entropy increase in the surrounding system; both rates must be equal when the fluid system is in a steady state. Possibility is shown with these expressions that the steady-state properties of several different types of turbulent phenomena (Bénard-type thermal convection, turbulent shear flow, and the general circulation of the atmosphere and ocean) exhibit a unique state in which the rate of entropy increase in the surrounding system by the turbulent dissipation is at a maximum. The result suggests that the turbulent fluid system tends to be in a steady state with a distribution of eddies that produce the maximum rate of entropy increase in the nonequilibrium surroundings.

Journal Article↗
PubMed2001

Effect of breath holding on blood flow measurement using fast velocity encoded cine MRI.

Breath-hold MR measurement of cardiac output was compared with results from respiratory triggered MR acquisitions, since flow measurement during breath-holding may be different from physiological blood flow. Cardiac output during large lung volume breath-holding (4.47 +/- 0.63 l/min in the aorta and 4.53 +/- 0.59 l/min in the pulmonary artery) was significantly lower than that measured during normal breathing (6.09 +/- 0.49 l/min and 6.48 +/- 0.67 l/min, P < 0.01). In contrast, no significant difference was found between measurements conducted with small lung volume breath-holding (5.87 +/- 0.53 l/min and 6.41 +/- 0.75 l/min) and normal breathing. In conclusion, breath-hold MR flow measurement using small lung volume by shallow inspiration can provide a blood flow quantification that is close to physiological blood flow. Magn Reson Med 45:346-348, 2001.

Adult↗
PubMed2001

Global myocardial blood flow and global flow reserve measurements by MRI and PET are comparable.

Coronary flow reserve (CFR) measurements have been widely used in assessing the functional significance of coronary artery stenosis because they are more sensitive in predicting major cardiac events than angiographically detected reductions of coronary arteries. Myocardial blood flow can be determined by measuring coronary sinus (CS) flow with velocity-encoded cine magnetic resonance imaging (VEC-MRI). The purpose of this study was to compare global myocardial blood flow (MBF) and CFR measured using VEC-MRI with MBF and CFR measured using positron emission tomography (PET). We measured MBF at baseline and after dipyridamole-induced hyperemia in 12 male volunteers with VEC-MRI and PET. With VEC-MRI, MBF was 0.64 +/- 0.09 (ml/min/g) at baseline and 1.59 +/- 0.79 (ml/min/g) at hyperemia, which yielded an average CFR of 2.51 +/- 1.29. With PET, MBF was 0.65 +/- 0.20 (ml/min/g) at baseline and 1.78 +/- 0.72 (ml/min/g) at hyperemia, which yielded an average CFR of 2.79 +/- 0.97. The correlation of MBFs between these two methods was good (r = 0.82, P < 0.001). The CFRs measured by MRI correlated well with those measured using PET (r = 0.76, P < 0.004). These results suggest that MRI is a useful and accurate method to measure global MBF and CFR. Therefore, it would be suitable for studying risk factor modifications of vascular function at an early stage in healthy volunteers.

Adult↗
PubMed2001

Time course of arterial hyperintensity with fast fluid-attenuated inversion-recovery imaging in acute and subacute middle cerebral arterial infarction.

The purpose of this study was to evaluate the time course of arterial hyperintensity (AH) in acute and subacute cerebral infarctions of the middle cerebral artery (MCA) distribution by using fast fluid-attenuated inversion-recovery (FLAIR) imaging. A total of 40 FLAIR MR examinations were performed in 27 patients with MCA infarction within 13 days after ictus. Thirteen patients underwent two MR examinations during this period. Thrombotic or embolic infarctions were included in this study, but lacunar infarctions were excluded. The presence or absence of AH and the location of AH were analyzed. Overall, AH was found in 24 (60%) of 40 FLAIR examinations within 13 days after onset. AH was seen in 17 (100%) examinations less than 24 hours old, four (40%) of 10 examinations 1-4 days old, two (18%) of 11 examinations 5-9 days old, and one (50%) of two examinations 10-13 days old. AH was most frequently found at the sylvian fissure (87%), followed by the sulci (54%), and the horizontal segment of MCA (29%) in the affected MCA distribution. Although AH could be seen even at 13 days after ictus, the presence of AH declined over time. AH represented an early sign of acute embolic or thrombotic infarction. J. Magn. Reson. Imaging 2001;13:987-990.

Aged↗
PubMed2001

Pulmonary ventilation-perfusion MR imaging in clinical patients.

The purpose of this study was to evaluate the feasibility of comprehensive magnetic resonance (MR) assessment of pulmonary perfusion and ventilation in patients. Both oxygen-enhanced ventilation MR images and first-pass contrast-enhanced perfusion MR images were obtained in 16 patients with lung diseases, including pulmonary embolism, lung malignancy, and bulla. Inversion recovery single-shot fast spin-echo images were acquired before and after inhalation of 100% oxygen. The overall success rate of perfusion MR imaging and oxygen-enhanced MR imaging was 94% and 80%, respectively. All patients with pulmonary embolism showed regional perfusion deficits without ventilation abnormality on ventilation-perfusion MR imaging. The results of the current study indicate that ventilation-perfusion MR imaging using oxygen inhalation and bolus injection of MR contrast medium is feasible for comprehensive assessment of pulmonary ventilation-perfusion abnormalities in patients with lung diseases.

Adult↗
PubMed2001

Immunohistochemical and ultrastructural study of basophilic inclusions in adult-onset motor neuron disease.

We immunohistochemically and ultrastructurally studied basophilic inclusions (BI) in a patient with adult-onset sporadic motor neuron disease (MND). BI were frequently observed not only in degenerated anterior horn cells, such as central chromatolytic neurons, but also in normal-appearing large anterior horn neurons. They had various shapes, round, elliptical or irregular, and occasionally they had distinct basophilic rims. They also varied in size. There were no halos around them nor core in their centers. Immunohistochemically, some BI were immunostained for ubiquitin or SOD1, but BI were not immunoreactive with anti-phosphorylated neurofilament (SMI 31), phosphorylated tau, cystatin C or Golgi (MG-160) antibodies. Ubiquitin-positive skein-like inclusions (SI) were occasionally observed in the somata of anterior horn neurons. Ultrastructurally, BI consisted of filamentous structures associated with granules, which were attached to thick filaments. The thick filaments were straight without constriction or side arms and their diameter was twice that of the neurofilaments. BI occasionally contained tubular structures among the granule-associated filaments. The granulo-filamentous profiles varied from being compactly arranged to being more loosely packed. The structure of BI resembles that of the Lewy body-like hyaline inclusions (LBHI) observed in sporadic MND patients. Bundles of filaments resembling SI, which were composed of compactly packed filaments without fine granules running parallel to the longitudinal axis, were frequently observed inside or at the periphery of BI, and occasionally clustered in the perikarya. Each filament measured approximately 15-25 nm in diameter, and a bundle of these grouped filaments was sometimes surrounded by a unit membrane. We also occasionally observed in-between structures of BI and bundles of filaments resembling SI. These findings suggest a certain relationship between BI, SI and LBHI in the pathomechanism of BI development. Further studies are needed to elucidate whether sporadic adult-onset MND characterized by BI forms a different subtype of MND.

Anterior Horn Cells↗
PubMed2001

Coronary flow reserve: measurement with transthoracic Doppler echocardiography is reproducible and comparable with positron emission tomography.

Detection of early vascular changes indicated by lowered coronary flow reserve (CFR) would allow early treatment and prevention of atherosclerosis. The purpose of this study was to test whether it is possible to reproducibly measure CFR with transthoracic Doppler echocardiography (TTE) in healthy volunteers. We measured CFR using dipyridamole infusion in ten healthy male volunteers with two methods: TTE and positron emission tomography (PET) with oxygen-15-labelled water (group A). However, CFR was assessed twice with TTE in eight healthy male volunteers (group B) to study the reproducibility of this method. We compared CFRs obtained using TTE flow measurements in the left anterior descending coronary artery (LAD) and PET flow measurements in the corresponding myocardial area. Coronary flow in LAD could be measured in all subjects using TTE. By TTE, an average CFR based on peak diastolic flow velocity (PDV) was 2.72 +/- 1.16, mean diastolic flow velocity (MDV) 2.56 +/- 1.06 and velocity time integral (VTI) 1.87 +/- 0.49. The results were reproducible in two repeated TTE studies (coefficient of variation in MDV 6.1 +/- 4.3%, n=8). By PET, CFR was 2.52 +/- 0.84. CFR assessed by TTE correlated closely with that measured by PET (MDV r=0.942, P<0.001; PDV r=0.912, P<0.002 and VTI r=0.888, P<0.006) and intraclass correlation was 0.929 (MDV) and tolerance limits for differences of CFRs was -0.78 to 0.72. We show that CFR measured by TTE has an excellent correlation with CFR measured by PET. We also found that TTE measurements of CFR were highly reproducible.

Adolescent↗
PubMed2001

Isolated unilateral absence of a pulmonary artery: influence of systemic circulation on alveolar capillary vessels.

We report a case of isolated unilateral absence of a pulmonary artery. The first clinical symptom that was manifested in the patient was recurrent hemoptysis, and subsequent angiography revealed that the main pulmonary artery was absent in the right lung, which was being fed only from the systemic circulation. Right pneumonectomy was performed, and neither the main pulmonary artery nor its remnant was detected in the resected right lung. Histologically, there were many muscular vessels in the resected lung, with intimal proliferation, or with plexiform-like lesions. The alveolar septum was moderately thickened and alveolar capillary vessels were dilated. We examined the alveolar capillary endothelial cells of the resected lung for immunoreactivity to thrombomodulin (TM) and von Willebrand factor (vWF). The endothelial cells were negative for TM and positive for vWF, while in the normal lung control group, these cells were positive for TM and negative for vWF. We considered that the hemodynamics of the systemic circulation in the resected lung caused the alteration of immunohistochemical characteristics in alveolar capillary endothelial cells.

Adult↗
PubMed2001

Assessment of coronary flow velocity reserve using fast velocity-encoded cine MRI for noninvasive detection of restenosis after coronary stent implantation.

PURPOSE: Serial change of the coronary flow velocity reserve was evaluated with fast velocity-encoded cine magnetic resonance imaging (MRI) for noninvasive detection of restenosis after coronary stent implantation. METHOD: In total, 60 MRI flow studies were performed in 10 patients with coronary artery disease who undersvent elective successful stent implantation to the lesion in the proximal left anterior descending artery. Flow velocities in the segment that was distal to the stent were measured before and after intravenous injection of dipyridamole. MRI measurements of coronary flow velocity reserve were repeated every 4 weeks for 6 months, and follow-up angiography was performed 6 months after the procedure. RESULTS: In patients without restenosis (n = 7, % diameter stenosis: 27.8%+/-7.1) at follow-up angiography, the coronary flow velocity reserve remained normal during the 6-month follow-up time. The flow velocity reserve was 2.31+/-0.30 at 1 month and 2.52+/-0.25 at 6 months after stent implantation (p = NS). In contrast, the coronary flow velocity reserve showed a significant decrease after 4 months in patients with restenosis (n = 3, % diameter stenosis: 66.3%+/-8.1) at follow-up angiography. The flow velocity reserve was 2.26+/-0.49 at 1 month and 1.52+/-0.09 at 6 months after stent implantation (p < 0.05). CONCLUSION: Fast velocity-encoded cine MRI is a technique that shows promise in providing non-invasive detection of restenosis of coronary stent implantation.

Adult↗
PubMed2001

Mr flow measurement in the internal mammary artery-to-coronary artery bypass graft: comparison with graft stenosis at radiographic angiography.

PURPOSE: To evaluate the sensitivity and specificity of breath-hold magnetic resonance (MR) flow measurement for detection of significant stenosis in internal mammary artery bypass grafts. MATERIALS AND METHODS: Twenty-six consecutive patients who had undergone coronary artery bypass surgery were examined. Breath-hold velocity-encoded cine MR images were obtained at the midpoint of the internal mammary artery between its origin from the subclavian artery and the distal anastomosis to the left anterior descending artery. RESULTS: MR images were obtained successfully in 24 patients. At conventional angiography, no significant stenosis was observed in 17 patients (group A), and significant stenosis (diameter > 70%) was observed in seven patients (group B). The mean diastolic-to-systolic peak velocity ratio in group B (0.61 +/- 0.44 [SD]) was significantly lower than that in group A (1.88 +/- 0.96; P <.01). Evaluation of graft stenosis with the diastolic-to-systolic peak velocity ratio revealed a sensitivity of 86% and a specificity of 88%. The mean blood flow rate at baseline in group B (16.9 mL/min +/- 5.5) was significantly lower than that in group A (79.8 mL/min +/- 38.2; P <.01). The sensitivity and specificity of MR blood flow measurement in predicting significant stenosis were 86% and 94%, respectively. The mean pharmacologic flow reserve ratios were 2.00 +/- 1.43 in group A and 1.39 +/- 1.46 in group B (P >.05). CONCLUSION: Fast MR blood flow measurement at baseline is highly useful for predicting significant stenosis in internal mammary arterial grafts.

Aged↗
PubMed2001

Association of nonpolio enteroviral infection in the central nervous system of children with febrile seizures.

OBJECTIVE: To clarify the relationship between enteroviral infection and febrile seizures. STUDY DESIGN: Cerebrospinal fluid (CSF), serum, throat swab, and rectal swab samples were collected for virologic examination from 67 children with febrile seizures from April 1997 to March 1999. Those samples were examined for the presence of enterovirus using cell culture and 2 polymerase chain reaction (PCR) methods. RESULTS: No enterovirus was isolated from cell culture of CSF, throat swab, or rectal swab samples. All samples were screened for the presence of enteroviral sequences using a sensitive PCR method (PCR-Fukushima). We obtained positive results from 14 of 67 CSF samples, 10 of 62 serum samples, 12 of 64 throat swab samples, and 13 of 64 rectal swab samples. Of 21 patients in whom febrile seizures had developed during the summer months (June through August), 13 (61.9%) had positive PCR results in the CSF. Forty-seven of the 49 samples with a positive result using PCR-Fukushima were reexamined independently for the presence of the enteroviral genome using another PCR method (PCR-Mitsubishi). PCR-Mitsubishi had slightly lower sensitivity than PCR-Fukushima but identified genotypes of enterovirus by subsequent sequence analysis of the PCR products. The presence of the enteroviral genome was confirmed in 39 of the samples (83.0%). In 8 of the 9 enteroviruses detected in the CSF and/or serum samples using PCR-Mitsubishi, the genotypes were identified as coxsackieviruses group A, which are usually difficult to isolate using cell culture methods. CONCLUSIONS: These findings proved that the causative agents of febrile illness associated with seizures in summer were primarily enteroviruses, especially coxsackieviruses group A, and that febrile seizures might be caused by enteroviral infection in the central nervous system.

Central Nervous System Diseases↗
PubMed2001

Assessing coronary sinus blood flow in patients with coronary artery disease: a comparison of phase-contrast MR imaging with positron emission tomography.

OBJECTIVE: This study was performed to determine whether MR imaging can be used to reliably measure global myocardial blood flow and coronary flow reserve in patients with coronary artery disease as compared with such measurements obtained by positron emission tomography (PET). SUBJECTS AND METHODS: We measured myocardial blood flow first at baseline and then after dipyridamole-induced hyperemia in 20 patients with coronary artery disease. Myocardial blood flow as revealed by MR imaging was calculated by dividing coronary sinus flow by the left ventricular mass. Coronary flow reserve was calculated by dividing the rate of hyperemic flow by the rate of baseline flow. RESULTS: Using MR imaging, myocardial blood flow at baseline was 0.73 +/- 0.23 mL x min(-1) x g(-1), and at hyperemia the blood flow was 1.43 +/- 0.37 mL x min(-1) x g(-1), yielding an average coronary flow reserve of 1.99 +/- 0.47. Using PET, myocardial blood flow was 0.89 +/- 0.21 mL x min(-1) x g(-1) at baseline and 1.56 +/- 0.42 mL x min(-1) x g(-1) at hyperemia, yielding an average coronary flow reserve of 1.77 +/- 0.36. The correlation of myocardial blood flow and coronary flow reserve measurements for these two methods was an r of 0.80 (p < 0.01) and an r of 0.50 (p < 0.05), respectively. CONCLUSION: This study shows that myocardial blood flow measurements obtained using MR imaging have a good correlation with corresponding PET measurements. Coronary flow reserve measurements obtained using MR imaging had only moderate correlation with PET-obtained measurements. Our results suggest that MR imaging flow quantification could potentially be used for measuring global myocardial blood flow in patients in whom interventional treatment for coronary artery disease is being evaluated.

Adult↗
PubMed2001

Properties of internal speed control and psychophysiological response during continuous forearm rotation movement.

This study investigated the properties of speed control and psychophysiological response when subjects changed movement speed internally. The task consisted of a continuous forearm rotational movement, which 14 women performed under 3 conditions, namely, (1) Preferred: the subject performed the task at a freely selected speed, (2) Slow: the subject changed the speed in two steps from preferred to a slower pace (slow, then very slow), (3) Fast: the subject changed the speed in two steps from preferred to a faster pace (fast, then very fast). Rotation speed and the coefficient of variation were measured to evaluate within-subject variability. Under the Preferred condition, there were no significant differences in rotation speed or coefficient of variation during the trials. However, under Slow and Fast conditions, the standard variation scores and coefficient of variation indicated different tendencies. Under the Fast condition, although the standard variation increased with the faster speed, the coefficient of variation decreased. On the other hand, the coefficient of variation increased under the Slow condition. Preferred speed had a significant positive relationship to the slow, very slow, fast, and very fast speeds. Heart rate (R-R interval) and EEG spectral intensity measurements showed no significant changes among the three conditions: however, respiration frequency significantly increased during Fast as compared to Preferred and Slow conditions. These results suggest that a preferred speed for continuous movement exists and that it is closely related to internal speed control as a psychological criterion. Furthermore, different movement speeds may reflect different psychophysiological responses.

Adult↗