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Biomedical subjects

T Yoshimoto

Publications and source records attributed to T Yoshimoto.

At least 343 records · Page 19Linked to original sources
PubMed1997

Glutathione-independent formaldehyde dehydrogenase from Pseudomons putida: survey of functional groups with special regard for cysteine residues.

The role of cysteine residues for structure and function of formaldehyde dehydrogenase from Pseudomonas putida was analysed by amino acid sequence comparison, homology-based structure modeling, site-directed mutagenesis, and chemical modification. Five out of seven cysteine residues found in the enzyme were concluded to coordinate with an active site zinc (Cys-46) and structural zinc atoms (Cys-97, -100, -103, and -111) from the sequence comparison with other Zn-containing medium-chain alcohol dehydrogenase homologues. The three-dimensional structure model based on the known structure of the horse liver E-type alcohol dehydrogenase (ADH) indicated that Cys-257 is located very far from the active site Zn and NAD+ binding region, suggesting that Cys-257 does not participate in the enzyme reaction. The structure also suggested that Cys-166 does not coordinate to active site Zn, but Asp-169 functions as a Zn-ligand, instead.

Aldehyde Oxidoreductases↗
PubMed1997

Prolyl endopeptidase inhibitors derived from actinomycetes.

Four prolyl endopeptidase inhibitors isolated from actinomycetes, named propeptin, SNA-8073-B, staurosporine, and enduracidin were classified into 3 groups on the basis of their inhibition potency against prolyl endopeptidase from a bacterium (Flavobacterium) and a mammal (human placenta). Staurosporine inhibited the enzyme from Flavobacterium more strongly than that from human placenta. Enduracidin inhibited the enzyme from human placenta more strongly than that from Flavobacterium. Propeptin and SNA-8073-B, both new compounds, inhibited the enzymes from both origins to the same extent.

Actinomycetaceae↗
PubMed1997

Gene expression of endothelial type isoform of nitric oxide synthase in various tissues of stroke-prone spontaneously hypertensive rats.

Nitric oxide (NO) has been suggested to play important roles in the pathophysiology of various cardiovascular diseases. This study tested the hypothesis that an attenuated biological action of NO in hypertension is attributed to a change in the gene expression of NO synthase (NOS), a key enzyme involved in NO formation. The expression level of mRNA of endothelial type NOS (NOS-III) was determined in stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and Wistar Kyoto rats (WKY/Izm) by ribonuclease protection assay using a partial clone as probe. NOS-III mRNA was expressed ubiquitously in various tissues of WKY/Izm and SHR-SP/Izm either at 5 wk or 13 wk of age. There was no significant difference in the tissue expression of NOS-III mRNA between the two strains at either age. The intensity and localization of the hybridization signal for NOS-III mRNA in the heart of SHR-SP/Izm did not differ from those in the heart of WKY/Izm. These results suggest that the attenuated biological action of NO implied in genetically hypertensive rats is not attributed to an abnormality at the level of NOS-III mRNA expression in the tissues, although lack of an increase in NOS-III gene expression, despite the hypertensive hemodynamic stress, may modify the blood pressure in hypertension.

Animals↗
PubMed1997

Left ventricular hypertrophy is more prominent in patients with primary aldosteronism than in patients with other types of secondary hypertension.

We determined functional and morphological changes of the heart by 2-dimensional and pulse Doppler echocardiography in 20 patients with primary aldosteronism and compared the results with those in 50 healthy normotensive subjects, 12 patients with Cushing's syndrome, 9 patients with pheochromocytoma, and 47 patients with essential hypertension. All hypertensive groups had greater left ventricular mass indexes than did the normotensive group (76.9 +/- 17.2 g/m2). Despite similar age distribution, blood pressure during antihypertensive treatment, and duration of hypertension, the primary aldosteronism group had a significantly greater left ventricular mass index (152.5 +/- 42.5 g/m2) than did the Cushing's syndrome (103.4 +/- 37.5 g/m2), pheochromocytoma (122.4 +/- 28.5 g/m2), and essential hypertension (101.4 +/- 32.8 g/m2) groups. The left ventricular posterior wall thickness and interventricular septal wall thickness were significantly greater in the hypertensive groups than in the normotensive group and also significantly greater in the primary aldosteronism group than in any of the other hypertensive groups. By contrast, there were no significant differences among the four hypertensive groups in any variable of systolic or diastolic function of the heart. The results suggest that left ventricular hypertrophy is more pronounced in patients with primary aldosteronism than in patients with other forms of hypertension. It is therefore important to echocardiographically evaluate cardiac hypertrophy as a risk factor of morbidity and mortality in patients with this low renin hypertension.

Adrenal Gland Neoplasms↗
PubMed1997

Striate cortical generators of the N75, P100 and N145 components localized by pattern reversal visual evoked magnetic fields.

Magnetic fields evoked by checkerboard pattern reversal visual stimulation to the monocular left or right half-field were recorded over the whole head using a helmet-shaped 64 channel magnetoencephalography system in fourteen normal subjects. The sources of the triphasic N75m-P100m-N145m responses were located using a single current dipole model. Relative locations and orientations of the N75m and N145m dipoles to the P100m dipole were calculated for each subject to reduce errors due to 'anatomical variability and then averaged for all subjects under the same stimulus conditions. These averaged parameters showed that N75m and N145m originated from the same location in the striate cortex as P100m and reversed their orientations successively by 180 degrees during the time course.

Adult↗
PubMed1997

Carcinomatous change in the cranial metastasis from a metastasizing mixed tumor of the salivary gland--case report.

A 57-year-old female who had had a mixed tumor of the submandibular gland for 30 years presented with a cranial metastasis in the ipsilateral occipital region. Detailed histological examinations of the primary tumor failed to detect any carcinomatous component. In contrast, the metastasis contained a carcinomatous component. This histological discrepancy was confirmed by assessment of the expression of Ki-67 antigen in these tumor specimens and comparison with five typical benign mixed tumors. Cranial metastasis of a histologically benign mixed tumor is extremely rare, and a carcinomatous change in the metastatic tumor is apparently unique.

Adenoma, Pleomorphic↗
PubMed1997

Adult respiratory distress syndrome in patients with malignant astrocytoma--three case reports.

Three patients treated for intracranial malignant astrocytomas developed adult respiratory distress syndrome (ARDS). All three patients had a Karnofaky performance status score of at least 80% and similar clinical characteristics. All demonstrated hypersensitivity to phenytoin. ARDS occurred in two patients during radiotherapy and in one with radiation-induced brain damage following initial radiochemotherapy. ARDS occurred shortly after tapering the long-term administration of betamethasone. The initial symptoms were dry cough, fever, and generalized toxic eruption. Serum lactic acid dehydrogenase (LDH) concentrations were increased up to 2500 IU/l. Several days later, the patients suddenly complained of dyspnea. All patients fulfilled the diagnostic criteria for ARDS. Two patients recovered, but a young woman died. Clinical symptoms such as fever of unknown origin, dry cough and skin eruptions, accompanied by abnormally increased serum LDH concentrations during or following the tapering of long-term administration of corticosteroids, are warning signs of ARDS in patients being treated for malignant gliomas.

Adult↗
PubMed1997

Probable brain abscess presenting as a high uptake lesion on thallium-201 single photon emission computed tomography--case report.

A 61-year-old male presented with a brain abscess manifesting as high fever and generalized convulsion attacks. Magnetic resonance (MR) imaging disclosed a ring-like enhanced lesion in the parietal lobe. Thallium-201 single photon emission computed tomography (201Tl SPECT) images demonstrated a high uptake lesion with a 201Tl uptake index on the early image of 2.21, which suggested malignant disease. The washout ratio was 0.73. His symptoms and the ring-like enhanced lesion on MR images disappeared after 2 months of antibiotic treatment. The final diagnosis was brain abscess, despite the 201Tl SPECT findings. 201Tl SPECT washout ratio may be a better indicator of brain abscess than uptake index.

Brain Abscess↗
PubMed1997

Effectiveness of fibrin glue for preventing postoperative extradural fluid leakage.

Cerebrospinal fluid (CSF) leakage through dural sutures after craniotomy increases the risk of complications such as persistent CSF fistulas, meningitis, and subcutaneous, graft bone, or epidural infections. The effectiveness of fibrin glue for preventing CSF leakage through dural closure was investigated in 183 patients who underwent frontotemporal craniotomy for unruptured aneurysm. Fibrin glue was used in 138 patients, but not in the other 45. Computed tomography was used to evaluate postoperative extradural fluid collection as a minimal volume of low-density area. Postoperative computed tomography demonstrated transient increases in extradural fluid collection in 55 patients. However, none of these patients received a second surgery for dural repair. Fluid collection occurred in 19 of 45 patients (42%) in whom fibrin glue was not used, and in 36 of 138 patients (26%) in whom fibrin glue was used. The fibrin sealant on the dural suture was a significant factor in reducing the incidence of the fluid leakage (p < 0.05, chi-square test). Fibrin glue is a useful surgical tool for the prevention of postoperative extradural fluid collection through the dural sutures.

Cerebrospinal Fluid↗
PubMed1997

Neuromagnetic evaluation of cortical auditory function in patients with temporal lobe tumors.

The N100m wave response of the auditory evoked magnetic field originates in the posterior part of the bilateral superior temporal planes for either contra- or ipsilateral ear stimulus. Cortical auditory function was evaluated in 14 patients with temporal lobe tumors using a magnetic resonance (MR) imaging-linked whole-head magnetoencephalography (MEG) system. Before surgery, seven patients had normal N100m latency (within the range of the mean +/- 2 standard deviations of 37 normal volunteers) in both normal hemispheres and in those with lesions, and MR imaging indicated no tumor invasion or edema in the posterior one-third of the superior temporal planes, even when the sylvian fissure was shifted upward due to the mass effect. Seven patients had prolonged N100m latency or absence of N100m in the hemisphere containing the lesion, and the posterior portion of the superior temporal plane was involved by the tumor or perifocal edema. Prolonged N100m latency recovered to the normal range after removal of tumors in two of four patients investigated postoperatively. The MEG system can be used to evaluate cortical auditory function noninvasively before and after surgical treatment of temporal lobe tumors.

Adult↗
PubMed1997

[Evaluation of various somatosensory stimulations for functional MRI].

The aim of this functional magnetic resonance imaging (fMRI) study was to test detectability of activated area using various somatosensory stimulations. The following stimulations were performed in normal volunteers: regular or irregular electrical median nerve stimulation (n = 5, each), tactile stimulation to the palm and fingers (n = 8), pain stimulation to the index finger (n = 5) or to the palm and fingers (n = 5). fMRI was acquired with a spoiled gradient echo sequence at 1.5 T. Detectability of activated area was the highest when the pain stimulation was applied to the palm and fingers (80%). A successful rate for the tactile stimulation was 25%, and the other stimulations failed to demonstrate any activation. When successful, the highest signal activation on fMRI was seen on a sulcus, which presumably arose from a vein. The sulcus was defined as the central sulcus by somatosensory evoked field using a median nerve stimulation. Our study indicates that the pain stimulation to the palm and fingers may be a choice for the sensory fMRI.

Adult↗
PubMed1997

[The expression of ICAM-1 and cytokines in the reperfusional state].

With a hypothesis that an inflammatory cascade composed of cell-to-cell interactions causes cellular damage secondary to reperfusion, I studied the temporary profiles of expression of intracellular adhesion molecule (ICAM)-1 and associating induction of proinflammatory cytokines in an acute phase following reperfusion of rat forebrain. Immunohistologically, ICAM-1 expression began to increase 1 hr after reperfusion in the microvessels of the subcortical region and the basal ganglia. Also, leukocyte positive of lymphocyte function associated antigen (LFA)-1 appeared attached to the capillary vessel walls 6 hrs after reperfusion. Semiquantitatively calibrated RT-PCR analysis was employed to assess the relative expression of mRNA. Increase of the mRNAs from the basal levels after reperfusion followed two different patterns; one, seen for ICAM-1, interleukin (IL)-1 alpha, beta, tumor necrosis factor (TNF)-alpha, and monocyte-chemoattractant protein (MCP)-1, exhibited an increase as early as 1 hr, and another, for IL-6 and macrophage migration inhibitory factor (MIF), showed a gradual increase up to 24 hr after reperfusion. The results were consistent with the proinflammatory properties of those immediately-induced cytokines, which may be involved in the initiation step of the inflammatory cascade, causing the secondary cellular responses. Furthermore, I found that MIF protein was expressed in neuropils in the cortex and basal ganglia by immunohistochemistry. Although precise pathophysiological role of MIF is still unclear, this protein may modulate immune reaction by leukocytes in secondary tissue damage following reperfusion stress. Clinically, I investigated soluble ICAM-1 in sera of patients with various cerebral ischemic diseases of acute stage (n = 28) and healthy adults (n = 23). The serum levels of sICAM-1 in patients with ischemic diseases, particularly with transient ischemic attack (TIA), were significantly higher (p < 0.01) than those of healthy individuals. These results together indicate that cell-cell interaction by adhesion molecules and cytokines is an important component in the pathogenesis of ischemic cerebral diseases, especially at the acute phase.

Acute-Phase Reaction↗
PubMed1997

[Spontaneous spinal epidural hematoma: case report].

We report a case of spontaneous spinal epidural hematoma (SSEH) at the upper thoracic level which accompanied an epidural vascular lesion demonstrated by histological examination. A 62-year-old male was referred to our department, because of sudden onslaught of back pain, progressive paraparesis, and sensory disturbance below the dermatome of Th8. He had no history of a tendency to bleed, anticoagulant therapy, or trauma. There was no abnormality in the laboratory data. MRI revealed that an epidural mass at the level of dorsal T1 and T2 was compressing the spinal cord. Multilevel spondylotic change and thickened yellow ligament were also noted. Sixteen hours after the onset, we performed laminectomy at T1 and T2 and evacuated the epidural hematoma. An unusual vascular-net like tissue was found on the dura mater after removal of the hematoma. Postoperatively, neurological symptoms disappeared within three weeks. Histological appearance of the vascular tissue was a cluster of vessels containing a dilated vein with partially thin wall due to lack of elastic and collagen fibers. In reviewing the literature, there are several reports describing vascular lesions, such as cavernous angioma and AVM, as possible etiologies of SSEH. In the present case, long lasting compression of the posterior epidural venous plexus by the thick yellow ligament might have resulted in formation of an abnormal vein which ultimately caused bleeding.

Dura Mater↗
PubMed1997

[Postoperative normalization of prolonged P100m latency in the visual evoked magnetic field in a patient with occipital meningioma].

A 49-year-old female with a left occipital parasagittal meningioma was found to have prolonged P100m latency of the pattern reversal visual evoked magnetic field only in the hemisphere containing the lesion. After total removal of the tumor, the P100m latency was normalized in the affected hemisphere. Based on current dipole models, all the P100m dipoles were localized at the lateral bottom of the calcarine fissures bilaterally, as indicated by our previous study with normal subjects. Since the tumor was located near the parietoocipital sulcus and distant from the primary visual cortex, disturbance of the higher visual cortex probably affected the P100m latency.

Brain Mapping↗