Search PubMed⌕ Search

Biomedical subjects

T Kumazaki

Publications and source records attributed to T Kumazaki.

At least 55 records · Page 3Linked to original sources
PubMed1999

Crossed cerebellar diaschisis: the role of motor and premotor areas in functional connections.

The authors assessed the relationship between crossed cerebellar diaschisis (CCD) and cortico-pontine cerebellar pathway (CPCP) damage in 29 chronic supratentorial infarct patients to elucidate the role of motor and premotor areas for functional cerebro-cerebellar connections. The CCD rate was calculated from side-to-side cerebellar count differences on 123I-IMP single-photon emission computerized tomography images. Neuronal damage was estimated by the three scores of computed tomography density from equal to normal brain tissue (score 0) to equal to cerebrospinal fluid (score 2) in the 4 major regions on CPCP; frontal association, motor and premotor, sensory and parietal associations, and the posterior limb of the internal capsule. Two-factor factorial ANOVA by the score and the region revealed significant differences of the CCD rate in the score factor (score 0 or 1 vs. score 2, p = < 0.05) and the independency of these two factors. Categories determined by the scores in each region were analyzed by multiple stepwise regression analysis using the theory of quantification I, in which significant correlation only between CCD and the necrotic density (score 2) in motor and premotor areas were demonstrated (r = 0.515, p = < 0.05). The authors conclude that neuronal loss in motor and premotor areas seem to contribute significantly to functional cerebro-cerebellar disconnections.

Adult↗
PubMed1999

Detection of alternative splicing of fibronectin mRNA in a single cell.

Pre-fibronectin mRNA is subject to alternative splicing at three sites, EDA, EDB and IIICS. We analyzed the alternative splicing of fibronectin mRNA in a single cell. Reverse transcription-polymerase chain reaction analyses showed cells that produced a single form of mRNA at each one of these sites as well as cells that produced multiple forms at a given site: for example, some cells produced either the EDA(+) or EDA(-) form of the mRNA and other cells produced both forms. About 80% of the cells produced both (+) and (-) forms of the mRNA at the EDA and EDB sites, and the remaining cells contained either the (+) or (-) form. Five forms of fibronectin mRNA can result from alternative splicing at the IIICS site. Complex combinations of alternative splicing products were observed among the individual cells: there were ten different combinations of mRNA isoforms with respect to the IIICS site. Statistically significant changes in alternative splicing at the IIICS site were observed during cellular senescence.

Alternative Splicing↗
PubMed1999

Effects of exogenous [Arg8]-vasopressin on borderline-hypertensive Hiroshima rats.

The interaction between [Arg8]-vasopressin and a vasopressin receptor antagonist, [d(CH2)5(1), O-Me-Tyr2, Arg8]-vasopressin, was examined in Hiroshima rats and normotensive control rats under pentobarbital anesthesia. [Arg8]-vasopressin dose-dependently increased the arterial pressure in both the Hiroshima and control rats, the pressor effect being greater in the Hiroshima rats. After the administration of a vasopressin antagonist (0.01 mg/kg), which by itself decreased arterial pressure only in the Hiroshima rats, the dose-response curve for [Arg8]-vasopressin was much more greatly shifted to the right in the control rats. These results indicate that with or without a vasopressin antagonist, the exogenous [Arg8]-vasopressin induced more powerful pressor actions in the Hiroshima rats compared to the control rats.

Anesthesia↗
PubMed1999

Value of magnetization transfer contrast as a sensitive technique to reflect histopathological changes in the white matter adjacent to the frontal horns of lateral ventricles.

The purpose of this study is to evaluate the usefulness of magnetization transfer contrast (MTC) as a technique to reflect histopathological changes in the white matter adjacent to the frontal horns of the lateral ventricles. Radiological-pathological correlation was performed in six patients who underwent Magnetic Resonance (MR) examination prior to death and in whom postmortem examinations of the brain were obtained. The extent and the severity of degeneration in the white matter adjacent to the frontal horns were evaluated histopathologically, and compared with those observed on the conventional proton density (PD) weighted MR images (Group 1). Changes in the white matter of another 35 patients were classified into three types according to the pattern of high signals adjacent to the frontal horns on conventional PD weighted MR images, and magnetization transfer ratio (MTR) in the white matter adjacent to the frontal horns was calculated from multi-slice and single-slice FSE images (Group 2). The relationship between signal intensities and MTR in the white matter adjacent to the frontal horns was evaluated. The extent of degeneration in the white matter adjacent to the frontal horns was classified into mild, moderate and severe types on the basis of stainin for myelins, axons and astrocytes. In Group 1, histopathological findings indicated a difference in severity of degeneration in the white matter adjacent to the frontal horns among the three types, while no significant differences were noted in the signals on PD weighted MR images. In Group 2, MTR showed significant differences in the signal intensities in the white matter adjacent to the frontal horns (p < 0.01) between the three types, while conventional PD weighted MR images failed to differentiate between them. In conclusion, MT imaging is a sensitive technique to evaluate the histopathological changes in the white matter adjacent to the frontal horns that cannot be detected by conventional MR imaging.

Adult↗
PubMed1999

Elimination of non-ionic contrast medium by hemodialysis in patients with impaired renal function.

The elimination rate of iohexol, a non-ionic contrast medium, from the blood by hemodialysis, and the elimination rate of iohexol by a dialyzer were studied in 15 patients with chronic renal dysfunction who required angiography or enhanced CT. The elimination rate of iohexol was 19.8% at 15 min after the start of hemodialysis, 30.6% after 30 min, 44.2% after 1 hour, 62.1% after 2 hours and 72.9% after 3 hours. The dialyzer elimination rate was maintained at about 75% from 1 to 3 hours after the start of hemodialysis. If only about 70% of iohexol in the blood needs to be eliminated, hemodialysis for 3 hours with a blood flow rate of 120 ml/min and a dialysate flow of 500 ml/min using a 0.7 m2 cellulose triacetate membrane is sufficient.

Contrast Media↗
PubMed1999

[Myocardial distribution of iodine-123-iodophenyl-9-methyl-pentadecanoic acid (9MPA) in patients with acute myocardial infarction: comparison with regional wall motion obtained from technetium-99m-sestamibi gated SPECT].

123I-iodophenyl-9-methyl-pentadecanoic acid (9MPA) is a modified long-chain (15 carbons) fatty acid with a methyl branch on its 9 carbon location. Myocardial SPECT images (two sets, 10 min each) were obtained starting 10 min (early phase) and 50 min (delay phase) after the injection of 160 MBq 123I-9MPA at rest in 10 patients with acute myocardial infarction. The segmental myocardial uptake (% uptake) and clearance (% washout) from early to delay image were calculated by the SPECT data. ECG-gated myocardial SPECT with 99mTc-sestamibi was also performed and segmental left ventricular (LV) wall motion was evaluated using QGS (quantitative gated SPECT) program. The % uptake of LV segments with hypokinetic or akinetic wall motion were significantly lower than those with normokinesis (p < 0.01) for both early and delay phases. The % washout of hypokinetic segments were significantly lower than those of normokinetic regions (p < 0.01), while the % washout of akinetic segments were significantly higher than those of severely hypokinetic segments (p < 0.05). Thus, 123I-9MPA myocardial distribution and clearance thought to be associated with left ventricular regional wall motion.

Fatty Acids↗
PubMed1999

Fluorescence spectroscopic and histochemical analysis using hematoporphyrin as a microenvironmental probe for atherosclerotic change in the human aorta.

Hematoporphyrin (HP) was used as a microenvironmental fluorescent probe to investigate the development of human atherosclerotic plaques. We compared the site of HP accumulation with changes in the HP fluorescence spectrum in atheromatous plaques and in a liposome control model, using a confocal laser scanning microscope equipped with a photonic multi-channel analyzer linked to a fluorescence spectrometer. Wavelength shifts of the two peaks of HP fluorescence (F1, 620 nm; and F2, 640-690 nm) were monitored, and the integrated F2/F1 ratio was calculated as a measure of HP fluorescence. The F1 peak is characteristic of a predominantly aqueous site. The ratio reflects selective changes in the distribution and overcrowding of HP molecules in the limited space of the artificial membrane model. Compared with a normal artery, the atherosclerotic lesions showed an increase in the area of HP fluorescence, increased fluorescence intensity, a red shift of the HP fluorescence spectrum, and an increased F2/F1 ratio. The F2/F1 ratio of the membranous structures was markedly greater in the cores of the fibrous plaques than in the other plaques. The F1 peak showed increased intensity in the atheromatous plaque core, whereas in hydrophilic fibrous regions, such as the cap of the plaque, the intensity of the F1 peak was lower than in the core region. HP aggregation was observed in damaged cells and in water surrounded by lipid in the atheromatous core. Using HP as a probe allowed us to determine not only the ionization or polarity of each region in the atherosclerotic plaques but also to detect the separation and fusion of the lipid bilayer or micelle lipids, as well as damage to the cellular membranes and cholesterol enrichment. These findings suggest that HP is useful for detecting clinically important changes in atherosclerotic lesions, to lipid-rich, unstable, and vulnerable plaques, which are closely associated with cardiovascular events.

Adult↗
PubMed1999

Three-dimensional CT angiographic assessment of vascular diseases using various postprocessing techniques: the voxel transmission and cruising eye view methods and their respective merits.

BACKGROUND: To assess the clinical usefulness of three-dimensional CT angiography (3D-CTA) with newly-developed three-dimensional reconstruction techniques; voxel transmission (VT) and cruising eye view (CEV) methods, for performing minimally invasive diagnostic imaging of vascular diseases. METHODS DESIGN: retrospective comparative study. SETTING: University Hospital, Japan. PATIENTS: fifty-five patients with vascular lesions confirmed by catheter angiography (20 patients with aortic aneurysms, 10 patients with aortic dissection, and 25 patients with peripheral arterial occlusive disease). MAIN OUTCOME MEASURES: minimally invasive, three-dimensional diagnosis of vascular diseases. RESULTS: Angiogram-like images with a diagnostic quality similar to that of catheter angiography were obtained by the three-dimensional CT angiography/voxel transmission (3D-CTA/VT) method. This method is useful for treatment planning and also valuable for assessing the effectiveness of treatment. Three-dimensional endoscopic images of the vessel interior were obtained by the three-dimensional CT angiography cruising eye method (3D-CTA/CEV). This also yielded precise information about the relationship between the vascular lesions and the aortic orifices. CONCLUSIONS: Three-dimensional CTA/VT and three-dimensional-CTA/CEV enable visualisation of vascular lesions from an infinite number of viewing angles, and are useful as minimally invasive diagnostic techniques for imaging the vasculature.

Aged↗
PubMed1999

[Composition of vascular tree using moving-table MR angiography: development and preliminary clinical experience with a semi-automated program combining stacks of MR angiographic images].

Moving-table MR angiography, combining a contrast enhanced MRA approach with table movement, has recently become available. This technique allows imaging of long, longitudinal anatomical regions of vasculature. We have developed a semi-automated program combining stacks of MRA images obtained from different image stations, and applied it to the reconstruction of vascular trees in twenty-five patients with peripheral arterial occlusive disease. Using this program, continuous vascular trees, extending from the abdominal aorta to lower leg (up to 124 cm), were semi-automatically reconstructed within two minutes from six different projection angles. Extensive vascular lesions were recognized three-dimensionally by moving image display mode.

Arterial Occlusive Diseases↗
PubMed1999

[Assessment of left ventricular contraction abnormalities with myocardial infarction using gated technetium-99m sestamibi SPECT: comparison of wall thickening and regional ejection fraction analysis for the detection of coronary artery stenosis].

ECG-gated myocardial Technetium-99m sestamibi SPECT is a useful technique to measure myocardial perfusion and function simultaneously. In this study, wall thickening (WT) and regional ejection fraction (rEF) using ECG-gated SPECT have been studied to determine which parameter would be more sensitive to detect coronary artery stenosis in patients with acute myocardial infarction (AMI). Forty-five patients (36 men, 9 women, mean age 63 +/- 9 years old) with AMI were examined. CAG was performed for all patients. ECG-gated SPECT was performed 60 min after the intravenous injection of 555 MBq 99mTc-sestamibi at rest. Commercially available software (QGS) was used to produce WT and rEF polar maps from acquired SPECT data. The WT and rEF polar maps were evaluated visually and quantitatively. WT indicated higher sensitivity (80.3% vs. 59.1%, p < 0.05) and accuracy (86.7% vs. 74.8%, p < 0.05) than rEF for detecting overall coronary artery stenosis on visual interpretation. On quantitative analysis, WT had higher specificity (91.3% vs. 75.4%, p < 0.05) and accuracy (85.9% vs. 72.6%, p < 0.05) than rEF for detecting overall coronary artery stenosis, and showed a higher specificity (93.8% vs. 59.4%, p < 0.01) and accuracy (88.9% vs. 62.2%, p < 0.01) for detecting LCX stenosis. Moreover, sensitivity of WT for detecting coronary artery stenosis without infarction was higher than that of rEF significantly in quantitative analysis (75.0% vs. 31.3%, p < 0.05). These results suggested that WT was superior to rEF for detecting the coronary artery stenosis in patients with and without myocardial infarction. We concluded that WT is more sensitive indicator to determine localization of regional left ventricular dysfunction in AMI than rEF.

Aged↗
PubMed1998

Enhanced expression of mitochondrial genes in senescent endothelial cells and fibroblasts.

It has been suggested that some mitochondrial genes are important in cellular senescence. In order to identify the mitochondrial genes that are involved in cellular senescence, we have constructed a cDNA library from senescent human vascular endothelial cells and isolated 86 senescence-specific cDNA clones by differential screening. Among the clones, we identified four distinct mitochondrial genes including NADH dehydrogenase subunit 2 (ND2), ND3, ATPase 6 and 16S ribosomal RNA. We then compared the levels of expression of these genes in young and senescent cells by using two endothelial and two fibroblast cell strains. Northern blot and slot blot hybridization confirmed that the expression levels of ND3, ATPase 6 and 16S rRNA were elevated in senescent cells of all four strains. The expression level of ND2 was also elevated during cellular senescence in three of the four strains. Because mitochondria are actively involved in oxidative phosphorylation and respiratory functions, the altered expression levels of these genes may participate in aging processes.

Adenosine Triphosphatases↗
PubMed1998

Rapid data acquisition protocol in ECG-gated myocardial perfusion SPECT with Tc-99m-tetrofosmin.

Into 25 patients with heart disorders, 99mTc-tetrofosmin 555-740 MBq was injected intravenously at rest. After 40 minutes, ECG-gated myocardial perfusion SPECT was performed with a two detector gamma camera VERTEX (ADAC), setting up two detectors to form a 90-degree angle. Sixteen frames per R-R interval were acquired during a 180 degree rotation from the RAO 45 degrees to the LPO 45 degrees. A pair of data sets with standard (SDA) and rapid data acquisition (RDA) protocols was collected. In an SDA protocol, SPECT imaging was performed for 50 sec per step in 5 degree angular steps (total acquisition time; 15 minutes). An RDA protocol was conducted with 12 sec per step, 6 degree angular steps (acquisition time, 3 minutes). LVEF (%) and LVEDV (ml) quantitated automatically with a QGS program showed excellent correlations between two protocols with correlation coefficients of 0.980 (p < 0.01) and 0.983 (p < 0.01), respectively. Subsequently visual assessment of regional wall motion based on a four-point grading system was carried out with a 3-D cine LV display. High complete agreement was gained with 158 (90.3%) out of total 175 segments, so that assessment of the global and regional LV function with the RDA protocol demonstrated high reliability and feasibility.

Electrocardiography↗
PubMed1998

Three-dimensional CT angiography of intracranial vasospasm following subarachnoid haemorrhage.

We evaluated the usefulness of three-dimensional CT angiography (3D-CTA) in the diagnosis of intracranial vasospasm following subarachnoid haemorrhage (SAH) in 13 patients suspected of having vasospasm on clinical grounds. The intracranial vessels were clearly shown by 3D-CTA in 12 patients. 3D-CTA revealed spasm in the vessels of nine patients. Catheter angiography performed in seven of these patients immediately after 3D-CTA confirmed vasospasm. A low-attenuation area was seen on CT in the other two patients, representing an ischaemic lesion due to the spasm. In nine patients, a second 3D-CTA was performed using the same technique 1 week after the first, showing no vasospasm. Initial 3D-CTA revealed no vasospasm change in three patients. Following 3D-CTA, one of these had conventional angiography, which also demonstrated no spasm.

Adult↗
PubMed1998

Spinal cord infarcts with contrast enhancement of the cauda equina: two cases.

We report two cases of infarcts of the spinal cord with contrast enhancement of the cauda equina on MRI. As enhancement of the infarcted spinal cord waned, that of cauda equina was definite. These appearances suggest disruption of the blood-tissue barrier and possibly hyperaemia of cauda equina following infarcts of the spinal cord.

Cauda Equina↗
PubMed1998

Correlation between water content and magnetization transfer ratio of the water component in bone marrow using gradient-echo imagings: normal case study.

OBJECTIVE: To determine the correlation between water content and magnetization transfer (MT) ratio of the water component in normal bone marrow using gradient-echo (GRE) magnetic resonance (MR) imaging. DESIGN: Three types of GRE sequence--using fat suppression, using a combination of MT and fat suppression techniques, and without MT or fat suppression--were performed in nine healthy subjects. The water content of bone marrow assessed with GRE imaging was compared with that assessed with MR spectroscopy in three cases. The correlation between water content and MT ratio was observed using GRE imaging in nine subjects. RESULTS AND CONCLUSIONS: The water content as assessed by GRE imaging and by MR spectroscopy were closely correlated (P<0.005, r=0.932). An inverse correlation between water content and MT ratio was observed in normal bone marrow (P<0.03, r=-0.432), which suggests that the water component in bone marrow includes free water protons.

Adipocytes↗