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Biomedical subjects

S Tamura

Publications and source records attributed to S Tamura.

At least 217 records · Page 12Linked to original sources
PubMed1998

Quantification of interstitial lung abnormalities with chest radiography: comparison of radiographic index and fractal dimension.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate two physical measures used for quantifying interstitial lung abnormalities on chest radiographs: the normalized radiographic index (RI) and the fractal dimension (FD). MATERIALS AND METHODS: The RI and FD were obtained from 50 regions of interest (ROIs) in lungs with mild interstitial abnormalities, 50 ROIs in lungs with severe interstitial abnormalities, and 50 ROIs in normal lungs. The RI was defined as the normalized percentage area of extracted opacities in selected ROIs. FD was calculated with a box-counting algorithm. To extract linear opacities selectively, the authors processed ROIs with four-directional Laplacian-Gaussian filtering and binarization, linear opacity judgment (LOJ), and linear opacity subtraction (LOS). The usefulness of the physical measures for quantifying interstitial lung abnormalities was evaluated with receiver operating characteristic analysis. RESULTS: In normal and mild abnormality groups, observer performance with the RI was worse with LOJ images (area under the receiver operating characteristic curve [Az] = .812 +/- .042) than with LOS images (Az = .912 +/- .028, P < .05), and performance with FD was better with LOJ images (Az = .867 +/- .037) than with LOS images (Az = .750 +/- .048, P < .05). In the normal and severe abnormality groups, performance with RI and FD was better with LOJ images (RI: Az = .992 +/- .007; FD: Az = .968 +/- .016) than with LOS images (RI: Az = .883 +/- .034, P < .001; FD: Az = .767 +/- .047, P < .0001). CONCLUSION: The RI is considered to reflect the sensitivity in the detection of interstitial lung abnormalities on chest radiographs. Conversely, the FD is considered to reflect specifically the linear opacities processed with LOJ.

Algorithms↗
PubMed1998

Aberrant expression and phosphorylation of beta-catenin in human colorectal cancer.

The cytoplasmic domain of cadherins is known to associate with the intracellular proteins, catenins, which link cadherins to the actin-based cytoskeleton. In this study, we immunohistochemically investigated the expression of beta-catenin as well as E-cadherin and alpha-catenin in 86 human colorectal cancers, and we analysed their coexpression pattern and relationship to clinicopathological factors. In cancerous tissues, the frequency of reduced expression of beta-catenin (28 of 86, 33%) was similar to that of E-cadherin (19 of 86, 22%), but less than that of alpha-catenin (47 of 86, 55%). All three molecules were expressed strongly, as was the normal epithelium, in 36 cases (42%), whereas the rest (50 cases, 58%) showed reduction in one of the molecules. The reduction of beta-catenin expression was significantly correlated with dedifferentiation, Duke's stage, lymph node metastasis and liver metastasis. Next, we examined tyrosine phosphorylation in the protein complex immunoprecipitated with E-cadherin, as E-cadherin function is down-regulated by receptor-type tyrosine kinase in vitro. It was of interest that up-regulation of tyrosine phosphorylation of beta-catenin was more frequently observed in cancerous tissues than in the matching normal mucosa. These results suggest that beta-catenin may have important regulatory roles within an E-cadherin-mediated adhesion system in human colorectal cancers.

Cadherins↗
PubMed1998

Significance of trilineage myelodysplasia in de novo acute myeloid leukaemia during remission rather than at diagnosis.

Patients with trilineage myelodysplasia (TMDS) in de novo acute myeloid leukaemia (AML) at diagnosis and remission were clinically evaluated between 1983 and 1996. AML with TMDS (AML/TMDS) was observed in 20 (12%) of 162 patients with de novo AML at diagnosis. Complete remission (CR) was achieved with combination chemotherapy in 12 (67%) of 18 AML/TMDS cases. This CR rate was relatively worse than the rate of 78% (106/136 cases) of AML without TMDS, but this difference was not significant. Disease-free survival curves also showed no difference between AML/TMDS and AML without TMDS. During remission, eight (67%) of 12 AML/TMDS cases had myelodysplastic remission marrow (AML/MRM). AML/MRM was also seen in seven (7%) of 106 AML cases without TMDS. The actuarial disease-free survival was significantly lower in AML/MRM than in AML without MRM (P = 0.0003). All of the AML/MRM cases exhibited early leukaemic relapse; median remission duration was only 9 months. Clonal changes occurred in two cases of AML/TMDS and five cases of AML/MRM at the time of relapse. These findings suggest that TMDS during remission predicts a poorer prognosis and early leukaemic relapse when compared with the absence of TMDS.

Acute Disease↗
PubMed1998

Expression and function of c-Met, a receptor for hepatocyte growth factor, during T-cell development.

The c-Met oncoprotein is a cell-surface receptor for hepatocyte growth factor (HGF). Signals through HGF and c-Met have been appreciated for their crucial roles in the development of many cell types, including liver cells. The present study examined whether c-Met is expressed in the thymus and whether c-Met/HGF signals can regulate T-cell development in the thymus. We have found that mRNA transcripts encoding c-Met are expressed in mouse thymus. The c-Met transcripts were expressed at higher levels in fetal and neonatal thymus than in adult thymus, and were mostly expressed by lymphoid cells rather than by stromal cells. Interestingly, the addition of HGF to fetal thymus organ cultures increased the generation of mature T cells expressing high levels of T-cell antigen receptors. These results indicate that c-Met is expressed in the thymus during early ontogeny, and that c-Met/HGF signals can promote T-cell development.

Animals↗
PubMed1998

Spatial perception in macroscopic and microscopic surgical manipulations: differences between experienced and inexperienced surgeons.

The spatial perceptions of the phantom surgical field with the naked eye and under the surgical microscope were analyzed in a group of experienced and a group of inexperienced neurosurgeons. The phantom surgical field contained a start point, a virtual gate, and a target point. The virtual gate was an invisible zone arbitrarily set in the phantom surgical field. The examinees were first instructed regarding the position of the invisible virtual gate. Then they were asked to point consecutively to the three points with a suction tube under three different circumstances: with the naked eye, under the microscope, and by watching a navigation monitor. A surgical navigator was used to record the three-dimensional position of the suction tip. The pointing deviation from the suction tip to the center of the virtual gate was evaluated. The pointing accuracy with the naked eye did not differ between the two groups, but that under the microscope was significantly better in the experienced group than in the inexperienced group. Fluctuations in pointing deviation were significantly greater in the inexperienced neurosurgeons, especially with the microscope. Further analysis demonstrated that these differences were attributable to poorer depth perception of the phantom surgical space among the inexperienced neurosurgeons.

Clinical Competence↗
PubMed1998

Mutation in PEX16 is causal in the peroxisome-deficient Zellweger syndrome of complementation group D.

Peroxisome-biogenesis disorders (PBDs), including Zellweger syndrome (ZS), are autosomal recessive diseases caused by a deficiency in peroxisome assembly as well as by a malfunction of peroxisomes, among which>10 genotypes have been identified. We have isolated a human PEX16 cDNA (HsPEX16) by performing an expressed-sequence-tag homology search on a human DNA database, by using yeast PEX16 from Yarrowia lipolytica and then screening the human liver cDNA library. This cDNA encodes a peroxisomal protein (a peroxin Pex16p) made up of 336 amino acids. Among 13 peroxisome-deficiency complementation groups (CGs), HsPEX16 expression morphologically and biochemically restored peroxisome biogenesis only in fibroblasts from a CG-D patient with ZS in Japan (the same group as CG-IX in the United States). Pex16p was localized to peroxisomes through expression study of epitope-tagged Pex16p. One patient (PBDD-01) possessed a homozygous, inactivating nonsense mutation, C-->T at position 526 in a codon (CGA) for 176Arg, that resulted in a termination codon (TGA). This implies that the C-terminal half is required for the biological function of Pex16p. PBDD-01-derived PEX16 cDNA was defective in peroxisome-restoring activity when expressed in the patient's fibroblasts. These results demonstrate that mutation in PEX16 is the genetic cause of CG-D PBDs.

Amino Acid Sequence↗
PubMed1998

Temperature-sensitive mutation in PEX1 moderates the phenotypes of peroxisome deficiency disorders.

The peroxisome biogenesis disorders (PBDs), including Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD), are autosomal recessive diseases caused by deficiency of peroxisome assembly as well as malfunction of peroxisomes, where >10 genotypes have been reported. ZS patients manifest the most severe clinical and biochemical abnormalities, while those with NALD and IRD show the least severity and the mildest features, respectively. PEX1 is the causative gene for PBDs of complementation group I (CG1), the highest incidence PBD, and encodes the peroxin, Pex1p, a member of the AAA ATPase family. In the present work, we found that peroxisomes were morphologically and biochemically formed at 30 but not 37 degrees C, in the fibroblasts from all CG1 IRD patients examined, whereas almost no peroxisomes were seen in ZS and NALD cells, even at 30 degrees C. A point missense mutation, G843D, was identified in the PEX1 allele of most CG1 IRD patients. The mutant PEX1, termed HsPEX1G843D, gave rise to the same temperature-sensitive phenotype on CG1 CHO cell mutants upon transfection. Collectively, these results demonstrate temperature-sensitive peroxisome assembly to be responsible for the mildness of the clinical features of PEX1 -defective IRD of CG1.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1998

Mutations in PEX10 is the cause of Zellweger peroxisome deficiency syndrome of complementation group B.

Peroxisome biogenesis disorders (PBD), such as Zellweger syndrome, are autosomal recessive diseases caused by a deficiency in peroxisome assembly as well as a malfunction of the peroxisomes, where at least 10 genotypes have been reported. We have isolated a human PEX10 cDNA (HsPEX10) by an expressed sequence tag homology search on a human DNA database using yeast PEX10 from Hansenula polymorpha, followed by screening of a human liver cDNA library. This cDNA encodes a peroxisomal protein (a peroxin Pex10p) comprising 326 amino acids, with two putative transmembrane segments and a C3HC4zinc finger RING motif. Both the N- and C-terminal regions of Pex10p are exposed to the cytosol, as assessed by an expression study of epitope-tagged Pex10p. HsPEX10 expression morphologically and biochemically restored peroxisome biogenesis in fibroblasts from Zellweger patients of complementation group B in Japan (complementation group VII in the USA). One patient (PBDB-01) possessed a homozygous, inactivating mutation, a 2 bp deletion immediately upstream of the RING motif, which resulted in a frameshift, altering 65 amino acids from the normal. This implies that the C-terminal part, including the RING finger, is required for biological function of Pex10p. PEX10 cDNA derived from patient PBDB-01 was defective in peroxisome-restoring activity when expressed in patient fibroblasts. These results demonstrate that mutation in PEX10 is the genetic cause of complementation group B PBD.

Amino Acid Sequence↗
PubMed1998

Relationship between extraosseous accumulation in bone scintigraphy with 99Tcm-HMDP and histopathology.

We assessed the relationship between 99Tcm-HMDP extraosseous accumulation (EOA), the histopathology of primary lesions and various laboratory findings. In 155 of 4824 patients, 163 EOA were noted. Of these, 33.7% were in the abdomen, 27.6% in the chest, 22.7% in the extremities, 9.8% in the pelvic area and 6.1% in the head and neck area. We found that 72.4% of EOA were due to malignant processes and 27.6% to benign processes. In the abdomen, 36.6% of the EOA were due to hepatocellular carcinoma and intestinal carcinoma. In the chest, 46.7% of EOA were a result of breast carcinoma. In the extremities, 28.7% of the EOA were due to sarcoma. The mean white blood cell count was elevated (8.0 +/- 6.3 x 10(3)) in patients with malignant processes. The mean serum haemoglobin and haematocrit in benign and malignant processes, for both males and females, were below normal values. All other laboratory findings were within normal limits. Significant differences in serum haemoglobin and haematocrit were noted between male and female patients with benign processes (P = 0.04 and P = 0.04, respectively). No other significant differences between benign and malignant processes were noted. Therefore, EOA is more frequently associated with malignant processes of primary lesions and is often accompanied by leukocytosis and anaemia.

Aged↗
PubMed1998

Antibody-forming cells in the nasal-associated lymphoid tissue during primary influenza virus infection.

Antibody-forming cell (AFC) responses in the nasal-associated lymphoid tissue (NALT) of BALB/c mice were examined following intranasal infection, mainly of the upper respiratory tract, with a small volume of influenza virus. The infection induced significant accumulation of T and B cells in NALT, peaking around day 7 post-infection. Virus-specific IgA, IgG and IgM AFC responses were induced, developing from day 5 and peaking at day 7; responses were predominantly IgA and IgG, followed by IgM. At peak, NALT contained the greatest number of IgA AFCs per total cells of the lymphoid tissues examined in the upper respiratory tract. The IgM AFC responses were induced in NALT cell cultures from uninfected mice following in vitro culture with influenza virus, indicating that at least a part of the AFCs in infected mice may have originated from specific B cell precursors in NALT. In parallel with the detection of AFCs in infected mice, virus-specific IgA antibodies appeared in the nasal wash and their appearance correlated well with virus clearance from the nasal area. These results suggest that virus-specific IgA antibodies, produced by IgA AFCs in NALT, play an important role in recovery from infection.

Animals↗
PubMed1998

A viewpoint determination system for stenosis diagnosis and quantification in coronary angiographic image acquisition.

This paper describes the usefulness of computer assistance in the acquisition of "good" images for stenosis diagnosis and quantification in coronary angiography. The system recommends the optimal viewpoints from which stenotic lesions can be observed clearly based on images obtained from initial viewpoints. First, the viewpoint dependency of the apparent severity of a stenotic lesion is experimentally analyzed using software phantoms in order to show the seriousness of the problem. The implementation of the viewpoint determination system is then described. The system provides good user-interactive tools for the semiautomated estimation of the orientation and diameter of stenotic segments and the three-dimensional (3-D) reconstruction of vessel structures. Using these tools, viewpoints that will not give rise to foreshortening and vessel overlap can be efficiently determined. Experiments using real coronary angiograms show the system to be capable of the reliable diagnosis and quantification of stenosis.

Coronary Angiography↗
PubMed1998

Image guidance of breast cancer surgery using 3-D ultrasound images and augmented reality visualization.

This paper describes augmented reality visualization for the guidance of breast-conservative cancer surgery using ultrasonic images acquired in the operating room just before surgical resection. By combining an optical three-dimensional (3-D) position sensor, the position and orientation of each ultrasonic cross section are precisely measured to reconstruct geometrically accurate 3-D tumor models from the acquired ultrasonic images. Similarly, the 3-D position and orientation of a video camera are obtained to integrate video and ultrasonic images in a geometrically accurate manner. Superimposing the 3-D tumor models onto live video images of the patient's breast enables the surgeon to perceive the exact 3-D position of the tumor, including irregular cancer invasions which cannot be perceived by touch, as if it were visible through the breast skin. Using the resultant visualization, the surgeon can determine the region for surgical resection in a more objective and accurate manner, thereby minimizing the risk of a relapse and maximizing breast conservation. The system was shown to be effective in experiments using phantom and clinical data.

Breast Neoplasms↗
PubMed1998

Maternal-fetal transfer of melatonin in pregnant women near term.

Our objective was to evaluate the maternal-fetal transfer of melatonin in pregnant women. Serum melatonin concentration was measured by high-performance liquid chromatography with electrochemical detection in a maternal vein and in the umbilical artery and umbilical vein at the time of birth. Blood samples were obtained from 12 women who had spontaneously delivered vaginally at night. A single oral dose of melatonin was administered to each of 33 patients who underwent a cesarean section, and, blood samples were taken at 1, 2, 3, or 4 hr after the administration of melatonin at delivery. Cesarean section was performed between 1300 and 1500 hr. The mean melatonin concentrations of melatonin in maternal peripheral venous blood and umbilical arterial and umbilical venous blood did not differ significantly, and positive correlations in the serum levels of melatonin were observed between the three sources of blood. The oral administration of 3 mg of melatonin to pregnant women led to marked increases in the serum levels of melatonin, with maximum levels observed 2 hr (21.84 +/- 2.09 ng/ml) after drug administration. Changes in serum levels of melatonin in the umbilical vein and artery resembled those found in the maternal vein. Serum melatonin concentrations did not differ significantly between the maternal vein and the umbilical veins. Serum levels of melatonin in the umbilical vein after the administration of melatonin were significantly and closely correlated with those in the maternal vein (r = 0.924, P < 0.001). These results suggest that, in humans, melatonin is transferred from the maternal to the fetal circulation both easily and rapidly. A potential for the therapeutic use of melatonin as an antioxidant exists in the patients with preeclampsia.

Adolescent↗
PubMed1998

In vivo antibacterial activities of sanfetrinem cilexetil, a new oral tricyclic antibiotic.

The in vivo antibacterial activities of a new oral trinem, sanfetrinem cilexetil (a prodrug of sanfetrinem), were evaluated in comparison with those of cefdinir and amoxicillin. Sanfetrinem cilexetil showed potent efficacy against experimental murine septicemia caused by Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli and against murine respiratory infections caused by Streptococcus pneumoniae. Likewise, in murine models of respiratory infection by penicillin-susceptible and penicillin-resistant S. pneumoniae, sanfetrinem cilexetil was more effective than amoxicillin in reducing the number of bacteria in infected lungs. These results were reflected in its potent in vitro activity and high levels in plasma.

Animals↗
PubMed1998

PEX12, the pathogenic gene of group III Zellweger syndrome: cDNA cloning by functional complementation on a CHO cell mutant, patient analysis, and characterization of PEX12p.

Rat PEX12 cDNA was isolated by functional complementation of peroxisome deficiency of a mutant CHO cell line, ZP109 (K. Okumoto, A. Bogaki, K. Tateishi, T. Tsukamoto, T. Osumi, N. Shimozawa, Y. Suzuki, T. Orii, and Y. Fujiki, Exp. Cell Res. 233:11-20, 1997), using a transient transfection assay and an ectopic, readily visible marker, green fluorescent protein. This cDNA encodes a 359-amino-acid membrane protein of peroxisomes with two transmembrane segments and a cysteine-rich zinc finger, the RING motif. A stable transformant of ZP109 with the PEX12 was morphologically and biochemically restored for peroxisome biogenesis. Pex12p was shown by expression of bona fide as well as epitope-tagged Pex12p to expose both N- and C-terminal regions to the cytosol. Fibroblasts derived from patients with the peroxisome deficiency Zellweger syndrome of complementation group III (CG-III) were also complemented for peroxisome biogenesis with PEX12. Two unrelated patients of this group manifesting peroxisome deficiency disorders possessed homozygous, inactivating PEX12 mutations: in one, Arg180Thr by one point mutation, and in the other, deletion of two nucleotides in codons for 291Asn and 292Ser, creating an apparently unchanged codon for Asn and a codon 292 for termination. These results indicate that the gene encoding peroxisome assembly factor Pex12p is a pathogenic gene of CG-III peroxisome deficiency. Moreover, truncation and site mutation studies, including patient PEX12 analysis, demonstrated that the cytoplasmically oriented N- and C-terminal parts of Pex12p are essential for biological function.

Amino Acid Sequence↗
PubMed1998

Assessment of vasoactive agents and vascular aging by the second derivative of photoplethysmogram waveform.

To evaluate the clinical application of the second derivative of the fingertip photoplethysmogram waveform, we performed drug administration studies (study 1) and epidemiological studies (study 2). In study 1, ascending aortic pressure was recorded simultaneously with the fingertip photoplethysmogram and its second derivative in 39 patients with a mean+/-SD age of 54+/-11 years. The augmentation index was defined as the ratio of the height of the late systolic peak to that of the early systolic peak in the pulse. The second derivative consists of an a, b, c, and d wave in systole and an e wave in diastole. Ascending aortic pressure increased after injection of 2.5 microg angiotensin from 126/74 to 160/91 mm Hg and decreased after 0.3 mg sublingual nitroglycerin to 111/73 mm Hg. The d/a, the ratio of the height of the d wave to that of the a wave, decreased after angiotensin from -0.40+/-0.13 to -0.62+/-0.19 and increased after nitroglycerin to -0.25+/-0.12 (P<0.001 and P<0.001, respectively). The negative d/a increased with increases in plethysmographic and ascending aortic augmentation indices (r=0.79, P<0.001, and r=0.80, P<0.001, respectively). The negative d/a reflects the late systolic pressure augmentation in the ascending aorta and may be useful for noninvasive evaluation of the effects of vasoactive agents. In study 2, the second derivative of the plethysmogram waveform was measured in a total of 600 subjects (50 men and 50 women in each decade from the 3rd to the 8th) in our health assessment center. The b/a ratio increased with age, and c/a, d/a, and e/a ratios decreased with age. Thus, the second derivative aging index was defined as b-c-d-e/a. The second derivative wave aging index (y) increased with age (x) (r=0.80, P<0.001, y=0.023x-1.515). The second derivative aging index was higher in 126 subjects with any history of diabetes mellitus, hypertension, hypercholesterolemia, and ischemic heart disease than in age-matched subjects without such a history (-0.06+/-0.36 versus -0.22+/-0.41, P<0.01). Women had a higher aging index than men (P<0.01). The b-c-d-e/a ratio may be useful for evaluation of vascular aging and for screening of arteriosclerotic disease.

Aged↗
PubMed1998

Lipid peroxidation, antioxidative enzyme activities, and cytosolic free calcium levels in rat hippocampus-derived cells exposed to free radicals.

To elucidate mechanisms of free radical-induced neuronal cell death, lipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS), three antioxidative enzyme activities (superoxide dismutase, glutathione peroxidase, and catalse), and cytosolic free Ca2+ (Ca2+i) were examined in rat hippocampus-derived cells (HV16-4) exposed to free radicals generated by a hypoxanthine-xanthine oxidase system. The viability of cells decreased with an increase in numbers of free radical positive cells in a dose-dependent manner of xanthine oxidase. The protein-bound TBARS did not change, whereas free TBARS increased at 135% of initial value. No remarkable change was observed in three antioxidative enzyme activities. On the other hand, Ca2+i increased after exposure followed by cell death. Furthermore, the addition of Co2+, a nonspecific Ca2+ channel blocker, delayed the increase of Ca2+i and subsequent cell death. These findings suggested that the influx of Ca2+ played a crucial role for HV16-4 cell death induced by free radicals.

Animals↗