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Biomedical subjects

S Tamura

Publications and source records attributed to S Tamura.

At least 181 records · Page 10Linked to original sources
PubMed1999

The usefulness of Tc-99m MIBI for evaluating brain tumors: comparative study with Tl-201 and relation with P-glycoprotein

PURPOSE: This study was undertaken to determine the usefulness of Tc-99m methoxyisobutylisonitrile (MIBI) in brain tumors compared with TI-201 imaging. The authors evaluated the correlation between MIBI uptake and the presence of P-glycoprotein, and also the relation between MIBI uptake in response to combined radiotherapy and chemotherapy in glioblastoma. MATERIALS AND METHODS: Thirty-four brain tumors composed of 15 glioblastoma multiforme (GBM), 5 anaplastic astrocytomas, 5 low-grade astrocytomas, and 9 metastases were evaluated. Early and delayed images were obtained for MIBI and Tl-201 scintigraphy. P-glycoprotein status in all GBM, 2 anaplastic astrocytomas, 2 low-grade astrocytomas, and 2 metastases were evaluated immunohistochemically. Patients with GBM were divided into an effective and a noneffective group according to the change in tumor size. MIBI uptake indices were compared for these two groups. RESULTS: Both radiopharmaceuticals accumulated in all GBM and anaplastic astrocytomas. In low-grade astrocytomas, only one case showed tracer uptake. In metastasis, two cases showed high uptake on early images and marked washout on delayed images. Uptake ratio values (early uptake ratio and delayed uptake ratio) in all tumors were significantly higher in MIBI than in Tl-201. Immunohistochemical studies showed that the metastases were positive for P-glycoprotein but the GBM were not. In low-grade astrocytomas, a few cells were positively stained. In relation to the therapeutic outcome of GBM, both the early and delayed uptake ratios of MIBI were significantly greater in the noneffective group. CONCLUSIONS: Although diagnostic ability was comparable in MIBI and Tl-201, the imaging quality was better in MIBI. Both radiopharmaceuticals are useful in differentiating low-grade glioma from high-grade glioma. MIBI delayed imaging could also reflect the presence of P-glycoprotein. Intense MIBI uptake was also predictive of a poor clinical outcome in GBM.

Journal Article↗
PubMed1999

Brain uptake of iodinated L-meta-tyrosine, a metabolically stable amino acid derivative.

The possibility of using L-meta-tyrosine (L-mTyr) with high metabolic stability and amino acid transport affinity was evaluated. mTyr was first separated into D- and L-isomers with high-performance liquid chromatography and both were labelled with non-carrier-mediated 125I. Biodistribution and pharmacological studies of radioiodinated mTyr in mice and rats were then performed. 125I-L-mTyr showed greater accumulation in the brain and the pancreas. It accumulated in the brain stereospecifically in the in vivo studies and by the L-tyrosine competitive energy dependent transport system in the in vitro studies. It was resistant to deiodination, appeared to have no retention mechanism and was rapidly excreted. 123I-L-mTyr has the potential of an amino acid transport marker, especially in the brain and the pancreas.

Animals↗
PubMed1999

Visualization of epileptogenic phenomena using cross-correlation analysis: localization of epileptic foci and propagation of epileptiform discharges.

The main objectives of the preoperative evaluation of a patient with medically intractable epileptic seizures are localization of the foci and propagation of the epileptiform discharges. Electrocorticographic (ECoG) data of intractable focal epilepsy were analyzed using an AR model, wavelet analysis, and cross-correlation analysis. In order to derive the time-shifts, the cross correlations of the epileptiform discharges were calculated between electrodes for every unit of time. Further analyses were made by means of a set of contour maps of the time-shifts and sequential two- and three-dimensional visualizations of the time-shift maps in order to localize the epileptic foci and study their propagation process. Two types of foci and propagation were revealed in the results. In the first type, epileptiform discharges were generated at localized focal sites and spread quickly to other sites. In the second type, the foci of epileptiform discharges, which appeared soon after the former bursts, were localized at more than one site, and the discharges tended to spread more slowly. The findings suggest that epileptic phenomena can be caused by at least two kinds of mechanisms in one patient: in the former, the propagation might be mediated through synaptic projections, while in the latter, the extracellular diffusion of an excitatory factor might play an important role. In addition, our newly developed visualization technique for the localization of epileptic foci and the propagation of epileptiform discharges should prove useful in the study of epileptogenesis etiology.

Brain Mapping↗
PubMed1999

Extraction of fluorescent dot traces from a scanning laser ophthalmoscope image sequence by spatio-temporal image analysis: Gabor filter and radon transform filtering.

The scanning laser ophthalmoscope (SLO) allows the tracking of fluorescent dot motion, thereby enabling the flow velocities in perimacular capillaries to be directly measured. These can serve as an important index of local retinal soundness or reflect the whole body circulation status in disorders such as diabetes. Although it is possible to perceive moving fluorescent dots with the human eye, they are so faint and unstable that it is difficult to detect them by conventional digital still-image processing methods. To solve this problem, we generated spatio-temporal images of the fluorescent dots in a capillary and applied Gabor filters tuned to the direction of the traces in order to detect them. Finally, by discriminating and integrating the output using two levels of threshold, we were able to extract their traces. Because the medium-size Gabor filter requires a considerable amount of time for two-dimensional convolution calculation, we prove that there is a certain equivalence between the Gabor filter, the radon transform, and the Hough transform. In the light of this, we propose a form of radon transform filtering that includes a radon transform Gabor filter as a very long Gabor filter. This allows a whole trace to be detected in a single step with a one-dimensional convolution, thereby shortening the processing time. In an experiment, 60% of the traces could be detected without error, which is sufficient to allow the mean flow velocity in a capillary to be measured.

Filtration↗
PubMed1999

A case of multiple sebaceous epithelioma: analysis of microsatellite instability.

Sebaceous gland tumor is a rare disease that is a sign of Muir-Torre syndrome, an autosomal, dominantly inherited genodermatosis characterized by the presence of at least one sebaceous gland tumor and a minimum of one internal malignancy. Recent studies have indicated that defective DNA mismatch repair occurs in Muir-Torre syndrome. Cutaneous lesions may occur before diagnosis of the internal cancer. We describe a 64-year-old male patient with multiple sebaceous epitheliomas with no evident internal malignancy. Microsatellite instability, determined by examining dinucleotide CA repeats at the microsatellite loci, was observed in DNA from one sebaceous epithelioma but not from the other two sebaceous epitheliomas or from one basal cell epithelioma with sebaceous differentiation, suggesting that this condition is unlikely to be due to germ-line mutation of mismatch repair genes.

Adenocarcinoma, Sebaceous↗
PubMed1999

Metallothionein expression correlates with the pathological response of patients with esophageal cancer undergoing preoperative chemoradiation therapy.

Immunohistochemical staining for metallothionein (MT) and p53 was performed on biopsy specimens of 30 patients with esophageal squamous cell carcinoma who had received curative resection following preoperative chemoradiation. The pathologic response to chemoradiation was a partial response in 19 cases and no change was observed in 11 cases. In 16 cases with MT-positive tumor, 10 (62.5%) showed no change. In 14 cases with MT-negative tumor, 13 (92.8%) showed partial response. In 8 patients with negative staining for p53 and MT, 7 were responders, whereas in 9 patients with positive staining for p53 and MT, 6 were nonresponders. The pathologic response was significantly associated with the prognosis (p = 0. 0167). The survival rate of the responders was significantly better than that of the nonresponders. These findings suggest that MT might be a prognostic marker, and consequently we can select the patients who will benefit from preoperative chemoradiation.

Chemotherapy, Adjuvant↗
PubMed1999

Early (4-7 days of age) dexamethasone therapy for prevention of chronic lung disease in preterm infants.

We conducted a comparative study to evaluate whether early (4-7 days of age) low-dose dexamethasone (DEX) therapy in preterm infants with surfactant-pretreated respiratory distress syndrome (RDS) would facilitate extubation and improve the clinical outcome. Twenty-six preterm infants with surfactant-pretreated RDS who were oxygen- and ventilator-dependent at 4 days of postnatal age were enrolled. Twelve infants were in the historical comparison group, and 14 infants were assigned to receive DEX 0.125 mg/kg i.v., every 12 h, for a total of 6 doses. At study entry, the two groups had a comparable clinical status. DEX therapy significantly facilitated weaning from mechanical ventilation (median interval, 6 vs. 24 days, p < 0.005) and shortened duration of oxygen supplementation (9 vs. 28 days, p < 0.05) as compared with the historical comparison group. At 28 days of age, the occurrence of chronic lung disease (CLD) was significantly lower (1/14 vs. 6/12, p < 0.05) and there was a significant decrease in the incidence of ventilator dependence (0/14 vs. 5/12, p < 0.05) in the DEX group. DEX therapy did not influence the incidence of significant complications such as infection, periventricular leukomalacia or retinopathy of prematurity. We conclude that in a selected high-risk group of preterm infants, early low-dose DEX treatment results in improvement in pulmonary outcome without significant side effects.

Apgar Score↗
PubMed1999

Autotransplantation and stent implantation for bilateral renal artery fibromuscular dysplasia.

A 36-yr-old male was found to have renovascular hypertension due to an occluded right renal artery and 70% stenosis in the left renal artery, caused by fibromuscular dysplasia. The right kidney was supplied by collateral blood flow, and secreted more renin than the left kidney. Two differential therapeutic approaches were taken: autotransplantation for the right kidney and percutaneous transluminal renal angioplasty followed by stent implantation for the left. The renovascular hypertension was treated with these therapies, preserving renal function in this patient.

Adult↗
PubMed1999

A cytogenetic and fluorescence in situ hybridization evaluation of interferon-alpha in the treatment of chronic myeloid leukemia.

The effect of interferon-alpha (IFN) for chronic myeloid leukemia (CML) in the chronic phase (CP) was retrospectively evaluated in comparison with that of busulfan (BU) or hydroxyurea (HU) given alone. Among 107 patients diagnosed with CML between 1982 and 1997, 72 CP cases evaluable for long-term follow-up included 13 patients treated with BU alone, 18 with HU alone, and 41 with IFN-based therapy. Complete cytogenetic response (CCR) was achieved in 4/41 IFN cases (10%), and partial or minimal cytogenetic response occurred in 18/41 IFN cases (44%). In contrast, no cytogenetic response (NCR) was achieved in any BU or HU case. IFN treatment for 6 to 60 months was needed to achieve CCR. Overall survival curves revealed that the IFN group had significantly better survival than BU and HU groups (p=0.008 and 0.04, respectively). A significant correlation was found between karyotypic findings and fluorescence in situ hybridization (FISH) analyses in IFN-treated cases (r=0.739, p=0.0001). In some cases, however, the two methods showed discrepancy; BCR/ABL-positive cells represented only 20-75% of interphase bone marrow cells in NCR cases, although all metaphases examined were positive for the Philadelphia chromosome (Ph). A discrepancy was also seen in CCR cases; up to 22% of cells assessed were BCR/ABL-positive. These findings suggest that IFN is a useful therapy for CML in CP, and may have a suppressive effect on the CML clone even in NCR cases. The results also indicate that a combination of FISH and cytogenetic analyses may provide more detailed information for evaluating the efficacy of IFN than conventional cytogenetics alone.

Adolescent↗
PubMed1999

[Adult case of isolated noncompaction of left ventricular myocardium revealed at hospitalization for tuberculous pleuritis].

A 48-year-old man was diagnosed with isolated noncompaction of the left ventricular myocardium. He had been suffering from dyspnea during light exercise since early February 1997, which worsened with time. Eventually, he visited our hospital on February 14. He was admitted urgently because orthopnea was observed and chest radiogram showed massive left pleural effusion. The diagnoses were pulmonary tuberculosis and tuberculous pleuritis. Echocardiography at admission showed generalized hypokinesis of the left ventricle, so we suspected that his condition was complicated by myocarditis. However, virus antibody levels were not elevated, and no obvious findings compatible with myocarditis or cardiomyopathy were obtained by right ventricular myocardial biopsy. Left ventricular contractility remained low and a trabecular mesh structure was seen at the left ventricular apex. Thus, the diagnosis was isolated noncompaction of the left ventricular myocardium. This disorder has been highlighted in pediatric patients, but few adult cases have been reported.

Echocardiography↗
PubMed1999

Fluconazole versus amphotericin B for the prevention of fungal infection in neutropenic patients with hematologic malignancy.

Effective prophylaxis against fungal infection is important in neutropenic patients with hematologic malignancies, but the best method remains unclear. We investigated the effectiveness of fungal prophylaxis with amphotericin B or fluconazole. We reviewed the data on fungal isolates, plasma (1-->3)-beta-D glucan (beta-D glucan) levels, febrile periods (the number of days with an axillary temperature > 38 degrees C), and the duration of an axillary temperature > 38 degrees C when the neutrophil count was < 500/microliter. Of the 124 patients studied, 57 had acute myelogenous leukemia, 19 had acute lymphoblastic leukemia, 18 had non-Hodgkin's lymphoma, six had chronic myeloid leukemia, three had adult T-cell leukemia, and five had chronic lymphocytic leukemia. There were no significant differences in clinical characteristics between the 70 patients treated with amphotericin B and the 54 patients given fluconazole. There was a significant decrease of fungal isolates (chi 2-test, p < 0.001), the plasma beta-D glucan level (Wilcoxon test, p = 0.0001), and the febrile period (t-test, p < 0.05) in the patients given fluconazole compared with those given amphotericin B. In neutropenic patients with hematologic malignancies, prophylaxis with fluconazole significantly decreased fungal isolation and other indicators of fungal infection when compared with amphotericin B. Fluconazole may therefore be more effective for fungal prophylaxis in these patients.

Adolescent↗
PubMed1999

[CT arteriography of hepatic tumors].

The liver has dual blood supply from the portal vein and hepatic artery. Computed tomographic findings of hepatic neoplasms are greatly influenced by hepatic blood flow, and abnormal portal and hepatic arterial blood flow needs to be examined separately by CT arteriography (CTA) and CT during arterial portography (CTAP). Both CTA and CTAP have advantages over conventional CT in that they can provide greater contrast enhancement of hepatic tumors by injecting contrast material directly into the hepatic or superior mesenteric arteries. The methods of CTA and CTAP are described. CTA and CTAP were useful in the detection of small hepatic lesions, evaluation of changes in hepatic parenchymal blood flow, and evaluation of portal flow in hepatocellular carcinoma, which contribute to the classification of HCC. In conclusion, CTA and CTAP were indispensable in selecting a therapeutic approach.

Carcinoma, Hepatocellular↗
PubMed1999

[Design and development of one-handed denture brush for bedridden people].

Oral care for elderly bedridden people is one of the most necessary forms of care, not only for prevention of oral infection or aspiration pneumonia, but also in order to savor the taste of food and to recover and maintain mental vitality through the improvement in oral function. We designed denture brush that can be handled with one-hand in order to support independence. People require cooperation between medical treatment, health, and welfare services. We introduced the newly designed denture brush as a means to support the improvement of QOL for elderly bedridden people, and we hope to see the spread and promotion of oral care.

Activities of Daily Living↗
PubMed1998

Computer-Aided Diagnosis (CAD) for Mammography: Preliminary Results.

PURPOSE: To evaluate the CAD system for screening mammograms. MATERIALS AND METHODS: Mammograms of patients with asymptomatic breast cancerwere examined retrospectively. A total of 260 screening mammograms from 65 patients (bilateral cranio-caudal and medio-lateral-oblique views from each) were tested by using the CAD system (ImageChecker M1000 system, R2 Technology, Los Altos, CA, USA). Results: With 0.58 microcalcifications marks/film and 0.20 mass marks/film set as the false positive rate, 100% of microcalcifications cases and 79% of mass cases were detected correctly. Conclusion: The CAD system has the potential to become a second reader. Further developments are expected to improve the accuracy of detection of mass lesions

Journal Article↗
PubMed1998

Selective suppression of stress-activated protein kinase pathway by protein phosphatase 2C in mammalian cells.

Protein phosphatase 2Calpha (PP2Calpha) or PP2Cbeta-1 expressed in COS7 cells suppressed anisomycin- and NaCl-enhanced phosphorylations of p38 co-expressed in the cells. PP2Calpha or PP2Cbeta-1 expression also suppressed both basal and stress-enhanced phosphorylations of MKK3b and MKK6b, which are upstream protein kinases of p38, and of MKK4, which is one of the major upstream protein kinases of JNK. Basal activity of MKK7, another upstream protein kinase of JNK, was also suppressed by PP2Calpha or PP2Cbeta-1 expression. However, basal as well as serum-activated phosphorylation of MKK1alpha, an upstream protein kinase of ERKs, was not affected by PP2Cbeta or PP2Cbeta-1. A catalytically inactive mutant of PP2Cbeta-1 further enhanced the NaCl-stimulated phosphorylations of MMK3b, MKK4 and MKK6b, suggesting that this mutant PP2Cbeta-1 works as a dominant negative form. These results suggest that PP2C selectively inhibits the SAPK pathways through suppression of MKK3b, MKK4, MKK6b and MKK7 activities in mammalian cells.

Animals↗
PubMed1998

Isoform-specific phosphorylation of fission yeast type 2C protein phosphatase.

Protein phosphatase 2C (PP2C) is one of the four major protein serine/threonine phosphatases of eukaryotes and is implicated in the regulation of various cellular functions. With the goal of elucidating the mechanism responsible for regulating PP2C functions, we investigated the significance of phosphorylation of fission yeast Ptc1, Ptc2, and Ptc3, the yeast orthologs of mammalian PP2C. Both Ptc2 and Ptc3 but not Ptc1 were phosphorylated stoichiometrically by casein kinase II on serine residues at their carboxy-terminal regions. Mutational analysis of Ptc2 and Ptc3 revealed that serine residues of the conserved sequence (Ser-X-Ser-X-X-Glu/Asp) of these proteins were the phosphorylation sites. Interestingly, the activities of Ptc2 and Ptc3 were decreased 25 +/- 7.5% and increased 55 +/- 3.7%, respectively, by phosphorylation. In addition, the same site(s) of Ptc2 was phosphorylated when the protein was expressed in fission yeast cells. These results suggest that phosphorylation of PP2C plays important physiological roles in fission yeast cells.

Amino Acid Sequence↗
PubMed1998

Clofibrate-inducible, 28-kDa peroxisomal integral membrane protein is encoded by PEX11.

We cloned a human PEX11 cDNA by expressed sequence tag homology search using yeast Candida boidinii PEX11, followed by screening of human liver cDNA library. PEX11 encoded a peroxisomal protein Pex11p comprising 247 amino acids, with two transmembrane segments and a dilysine motif at the C-terminus. Pex11p comigrated in SDS-PAGE with a 28-kDa peroxisomal integral membrane protein (PMP28) isolated from the liver of clofibrate-treated rats and was crossreactive to anti-PMP28 antibody, thereby indicating PEX11 to encode PMP28. Pex11p exposes both N- and C-terminal parts to the cytosol. PEX11 was not responsible for ten complementation groups of human peroxisome deficiency disorders.

Amino Acid Sequence↗