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Biomedical subjects

J Kitamura

Publications and source records attributed to J Kitamura.

At least 19 recordsLinked to original sources
PubMed2001

Task-related signal decrease on functional magnetic resonance imaging.

An atypical pattern of signal change was identified on functional magnetic resonance (fMR) imaging in pathologic patients. Three normal volunteers and 34 patients with pathologic lesions near the primary motor cortex underwent fMR imaging with echo-planar imaging while performing a hand motor task. Signal intensities were evaluated with the z-score method, and the time course and changes of the signal intensity were calculated. Nine of the 34 patients with pathologic lesions displayed a significant task-related signal reduction in motor-related areas. They also presented a conventional task-related signal increase in other motor-related areas. The time courses of the increase and decrease were the inverse of each other. There was no significant difference between rates of signal increase and decrease. Our findings suggest that this atypical signal decrease is clinically significant, and that impaired vascular reactivity and altered oxygen metabolism could contribute to the task-related signal reduction. Brain areas showing such task-related signal decrease should be preserved at surgery.

Adolescent↗
PubMed2001

Saccular aneurysm of pulmonary autograft after the Ross procedure.

The Ross procedure, which includes removal of the malformed aortic valve and replacement of a pulmonary autograft in the aortic position, has increased the number of available treatment options. Recently, dilatation of the autograft pulmonary root after the Ross procedure has been reported as a complication. We report a patient with bicuspid aortic valve malformations and aortic annulus dilatation, who had a saccular-form, true-type, aneurysm in the pulmonary autograft seven months after the Ross procedure. These changes have not been described so far as complication. Pathologically, marked mucoid degeneration was noted in the tunica media of the aneurysm, as well as in the original aortic root. These findings may suggest similar pathological characteristics between the aorta and pulmonary arteries. Hence, the surgical risks accompanying vascular characteristics in patients with congenital aortic valve malformations should be considered.

Adult↗
PubMed1999

The contributory role of interstitial water in Gd-DTPA-enhanced MRI in myocardial infarction.

We studied the mechanism underlying regional enhancement of myocardial infarction using T1-weighted MRI with gadolinium (Gd)-DTPA. Anterior myocardial infarction (MI) was produced by left anterior descending coronary artery ligation in three groups of rats as follows: 60 minutes occlusion (occlusion group, N = 6), 60 minutes occlusion plus 120 minutes reperfusion (reperfusion group, N = 8), and sham-operated (control, N = 6). In Gd-DTPA-enhanced MRI, MI was demarcated as a hypoenhanced region in the occlusion group and as a homogeneous hyperenhanced region in the reperfusion group. Both Gd-DTPA tissue concentration and tissue water content in the anterior wall were highest in the reperfusion group (P<0.05), a finding suggestive of microscopically observed interstitial edema. The data suggest that regional accumulation of Gd-DTPA in the reperfused group can be explained by increased interstitial water content, contributing to the delayed washout of the water-soluble contrast medium.

Animals↗
PubMed1999

Cortical potentials preceding voluntary finger movement in patients with focal cerebellar lesion.

OBJECTIVE: To elucidate influences of the dentate nucleus on the generation of the related cortical potentials (MRCPs) preceding voluntary movement, Bereitschaftspotential (BP) and negative slope (NS). DESIGN AND METHODS: MRCPs preceding self-paced voluntary finger movement were recorded in 5 cases with localized cerebellar lesions due to stroke or tumor. Comparing 3 of them involving the dentate nucleus and 2 others sparing it, as judged from CT or MRI findings. RESULTS: BP and NS preceding voluntary finger movement ipsilateral to the lesion were absent or markedly reduced in amplitude in those 3 cases with the dentate nucleus lesion, whereas those negative components were present in the 2 cases with no evidence of dentate lesion. CONCLUSION: The dentate nucleus has a facilitatory effect on the generation of BP and NS.

Adult↗
PubMed1999

Long-latency reflexes in contracted hand and foot muscles and their relations to somatosensory evoked potentials and transcranial magnetic stimulation of the motor cortex.

OBJECTIVE: The cortical relay time (CRT) for V2 of long-latency reflexes (LLRs) in the contracted thenar and short toe flexor muscles was studied. METHODS: LLRs and somatosensory evoked potentials (SEPs) were studied by electrical stimulation of the median or posterior tibial nerve. The CRT for V2 was calculated by subtracting the onset latency of cortical potentials in SEPs and that of motor evoked potentials (MEPs) by transcranial magnetic stimulation (TMS) from the onset latency of V2 in eight healthy subjects. RESULTS: The CRT for the thenar muscles was 11.4+/-0.9 ms (mean +/- SD), as the onset latency was 48.8+/-1.4 ms for V2, 16.0+/-1.2 ms for N20 and 21.3+/-1.1 ms for MEP, respectively. The CRT for the short toe flexor muscles was 3.0+/-1.3 ms, as the onset latency was 80.5+/-4.5 ms for V2, 35.3+/-1.8 ms for P38 and 42.2+/-2.0 ms for MEP, respectively. CONCLUSION: Significantly longer CRT for V2 for the thenar muscles (P<0.001, paired Student's t test) may indicate more synaptic relays as compared to that for the short toe flexor muscles.

Adult↗
PubMed1999

Gadolinium-DTPA-enhanced magnetic resonance imaging and functional outcome in patients with acute myocardial infarction.

This study was designed to test the hypothesis that Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced magnetic resonance images (MRI) reflect the severity of ischemic injury during the acute and chronic phases of myocardial infarction (MI). Twenty-nine patients with their first acute MI underwent Gd-DTPA-enhanced MRI in the first week (4.2+/-0.3 days) and at 1 month after onset. Pairs of left ventriculograms were compared with Gd-DTPA-enhanced magnetic resonance images, classified into 3 pattern groups: hyper-enhancement, with and without a central hypo-enhanced region (P1 and P2, respectively), and non-enhancement (P3). In the acute phase of MI, P1 was found in 10, P2 in 11, and P3 in 8 patients. One month later, the image pattern had changed from P1 to P2 in a single patient, from P2 to P3 in 4 patients, and had remained identical in the others. Patients with P3 showed improvement of anterior wall motion in the 1-month follow-up study, and had higher TIMI flow grades and lower peak creatine kinase values than those without recovery. Thus, Gd-DTPA-enhanced magnetic resonance images, closely reflecting the severity of myocardial injury, are useful in predicting myocardial functional recovery after MI.

Adult↗
PubMed1999

Hemorrhagic myocardial infarction after coronary reperfusion detected in vivo by magnetic resonance imaging in humans: prevalence and clinical implications.

With the advent of thrombolytic therapy, hemorrhagic myocardial infarction (HMI) has been observed in experimental and human autopsy studies. However, its clinical implications remain undetermined, because of the absence of a reliable method to detect its presence in vivo. This study was designed to evaluate the clinical implications of HMI detected by magnetic resonance (MR) imaging in vivo after coronary reperfusion. Thirty-nine patients with acute myocardial infarction (AMI) were studied. Percutaneous transluminal coronary angioplasty (PTCA) was used to reopen the occluded coronary artery. Electrocardiogram (ECG)-gated T2*-weighted gradient-echo MR imaging was performed to detect intramyocardial hemorrhage, using a 1.5-T magnet within 2 weeks after coronary reperfusion (average, 5.7 days). Thirteen patients (33%) showed intramyocardial hemorrhage as a distinct hypointense zone by gradient-echo MR imaging and 26 patients showed homogeneous intensity consistent with absence of intramyocardial hemorrhage. Coronary angiograms showed lesser development of collateral flow in the patients with HMI than in those without (81% vs. 37%). Infarct size, estimated 1 month after coronary reperfusion by thallium-201 scintigraphy, was larger among patients with HMI than in those without (37 +/- 14% vs. 21 +/- 14%, respectively, p < 0.05). Left ventricular ejection fraction at 1 month follow-up showed less recovery in patients with HMI than in those without (47 +/- 9 to 51 +/- 10%; p = 0.47, vs. 53 +/- 10 to 60 +/- 9%, respectively, p < 0.05). ECG-gated T2*-weighted gradient-echo MR imaging offers a noninvasive means of detection of intramyocardial hemorrhage in patients with reperfused AMI. HMI occurred even after primary PTCA and may be a common finding associated with severely injured myocardium.

Aged↗
PubMed1999

[Left ventricular relaxation in lone atrial fibrillation and atrial fibrillation with heart disease].

Atrial fibrillation with organic heart disease shows a steady value for the time constant of left ventricular isovolumetric relaxation (TC), whereas left ventricular contractility varies from beat to beat. However, there is no report on left ventricular relaxation in lone atrial fibrillation. This study assessed left ventricular relaxation in 5 patients with lone atrial fibrillation, 3 with ischemic heart disease and one with hypertrophic cardiomyopathy. Left ventricular pressure was recorded at 3 msec intervals, with a high fidelity micromanometer-tipped catheter. Maximal positive dP/dt (dP/dtmax) and TC of isovolumetric left ventricular relaxation period [P(t) = (P0-P infinity) exp (-t/TC) + P infinity] were measured as indices of left ventricular contractility and left ventricular relaxation, respectively. Correlation coefficients of dP/dtmax and TC versus the ratio of the preceding to the pre-preceding RR-interval (RR2/RR1) were calculated. A good correlation was found between dP/dtmax and RR2/RR1 in all patients (r = 0.71-0.84, p < 0.0001). No correlation between TC and RR2/RR1 was found in patients with atrial fibrillation with organic heart disease, but a good correlation was found between TC and RR2/RR1 in patients with lone atrial fibrillation (r = 0.74-0.95, p < 0.0001). The correlation between TC and RR2/RR1 is well preserved in lone atrial fibrillation. The mechanism of the variation of TC with the RR2/RR1 interval in lone atrial fibrillation may be similar to the change of TC in postextrasystolic potentiation, which is attributed to the change of intracellular Ca2+ concentration. Absence of correlation between TC and RR2/RR1 interval may indicate that left ventricular relaxation is disturbed in patients with atrial fibrillation with organic heart disease.

Aged↗
PubMed1998

Transcardiac 5-hydroxytryptamine release and impaired coronary endothelial function in patients with vasospastic angina.

1. The present study was designed to test the hypotheses whether platelet degranulation across the coronary bed is detectable during non-ischaemic periods in patients with vasospastic angina (VSA) and whether the exogenous nitric oxide (NO) donor nitroglycerin (GTN) is able to modify platelet degranulation, reflecting an impaired endothelial production of NO. 2. We studied 13 patients with VSA and 10 controls. The time course of coronary sinus (CS) plasma 5-hydroxytryptamine (5-HT) levels was evaluated every 4 h before and after intravenous infusion of GTN over a period of 40 h. Coronary sinus plasma 5-HT levels were significantly higher at any measured time point in patients with VSA compared with control and were significantly decreased in patients with VSA following treatment with GTN, but not in controls. Femoral artery plasma 5-HT levels remained almost constant throughout the study. The ratio of CS:aorta 6-keto-prostaglandin F1 alpha was significantly and inversely correlated with the transcardiac plasma 5-HT difference only in patients with VSA (r = -0.68; P < 0.02; n = 13). 3. The time course of CS 5-HT levels confirmed significant platelet degranulation across the coronary bed supplied by the spasming artery in patients with VSA and this was modified by GTN. The present data suggest that platelet degranulation occurs during non-ischaemic periods in patients with VSA and that prostacyclin biosynthesis may be a compensatory response to an impaired endothelial release of NO, limiting the degree of the effects of platelet degranulation.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

[Electroencephalography and prognosis in stroke patients].

Electroencephalography (EEG) and its relationship to prognosis were studied in 105 patients with cerebrovascular disease in the acute to subacute stages. Twenty cases had normal EEG, and most of them recovered well. Fifty-five cases had mildly to moderately abnormal EEG with focal asymmetric or slow waves in the unilateral hemisphere. Among them, 41 cases (75%) recovered to the extent of being capable of independent walking, 38 cases (69%) recovered sufficiently to engage in independent activities of daily livings (ADL) and 42 cases (76%) returned home. On the other hand 30 cases who had severely abnormal EEG with diffuse slow waves in the unilateral or bilateral hemispheres showed a poor prognosis. Among them, 18 cases (60%) were confined to bed, 20 cases (69%) remained in totally dependent ADL, and 4 cases (13%) died. Thus, EEG is shown to reflect well functional recovery in stroke patients.

Activities of Daily Living↗
PubMed1997

Ethanol sclerosis: one of the best treatments for thymic cyst in very elderly patients?

An 83-year-old female patient with a giant thymic cyst that was successfully treated by percutaneous aspiration and ethanol injection. The patient had complained of coughing and chest discomfort for several years. A chest X-ray film revealed the shadow of a large abnormal mass in the anterior mediastinum. We diagnosed it as a thymic cyst. The patient refused surgery because of her age. We chose a less invasive therapy, namely, ethanol sclerosis of the cyst. The cyst was successfully treated without any complications, and no recurrence was found at the one-year follow-up. This therapy may be one of the best treatments for thymic cysts, especially in very elderly patients.

Aged↗
PubMed1997

[Influence of atrioventricular delay on pulmonary capillary wedge pressure in two patients with hypertrophic obstructive cardiomyopathy during dual chamber pacing].

Recently, dual chamber pacing has been proposed as a new treatment for left ventricular outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, dual chamber pacing may be detrimental to both systolic and diastolic function of the left ventricle, particularly at short atrioventricular (AV) delay. A 45-year-old man and a 58-year-old woman with HOCM underwent transesophageal echocardiography and hemodynamic study at various AV delays (50-200 msec). In both patients, shortening of AV delay increased pulmonary capillary wedge pressure. The transesophageal echocardiographic study showed a remarkable shortening of the ventricular filling duration at atrial systole and an increase of pulmonary venous reversal at short AV delay (50-100 msec). Therefore, short AV delay was detrimental to diastolic filling and thus increased pulmonary capillary wedge pressure. Transesophageal echocardiographic study may be helpful for defining the optimal AV delay more precisely in HOCM during dual chamber pacing.

Blood Flow Velocity↗
PubMed1996

Increased serotonin release across the coronary bed during a nonischemic interval in patients with vasospastic angina.

BACKGROUND: Platelet activation and coagulation abnormality have been observed during coronary spasm. It is crucial whether platelet activation occurs even during a nonischemic period. HYPOTHESIS: This study was designed to determine whether platelets might be activated across the coronary bed during a nonischemic interval in patients with vasospastic angina. METHODS: Plasma levels of serotonin, 6-keto-prostaglandin F1 alpha, and catecholamines in the aorta and the coronary sinus were simultaneously measured in 16 patients with vasospastic angina and 13 control patients with nonischemic heart disease. RESULTS: None of these patients showed myocardial ischemia during sampling. The difference in transcardiac plasma levels of serotonin in patients with vasospastic angina was significantly higher than that in controls (1.48 +/- 1.08 ng/ml vs. 0.07 +/- 0.12 ng/ml, respectively, p < 0.001). Coronary sinus plasma norepinephrine levels in these two groups were almost the same (204.8 +/- 110.8 pg/ml vs. 190.4 +/- 131.6 pg/ml, respectively). The ratio of 6-keto-prostaglandin F1 alpha in the coronary sinus and the aorta was not different between the two groups (1.17 +/- 0.96 in patients with vasospastic angina vs. 1.15 +/- 0.68 in controls). CONCLUSIONS: These data suggest that platelet activation across the coronary bed should be ascribed to endothelial dysfunction. Lack of compensatory enhancement of prostacyclin production might be concerned with dysfunction of coronary endothelial cells in these patients.

6-Ketoprostaglandin F1 alpha↗