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S Obata

Publications and source records attributed to S Obata.

At least 37 records · Page 2Linked to original sources
PubMed1996

Narrow photon beam dosimetry for linear accelerator radiosurgery.

The dosimetric characteristics of linear accelerator radiosurgery for 10-MV X-ray were measured. Measurement of the relative output factor and tissue maximum ratio with a microchamber produced results equivalent to those of measurement with X-ray film. The 80% isodose level width measured with the microchamber was significantly smaller than that measured with the X-ray film. For the measurement of relative output factor and tissue maximum ratio, a microchamber seems to be the more appropriate choice. X-Ray film was found to be suitable for beam profile measurement.

Phantoms, Imaging↗
PubMed1996

Brief reactive psychosis induced by sensitivity training: similarities between sensitivity training and brainwashing situations.

Sensitivity training (ST), which originated in the USA during the late 1940s, has been used as part of training seminars in Japanese corporations since the late 1950s. The possibility of negative psychiatric effects of ST, and especially its role in inducing psychiatric symptoms, is yet to be clarified. A case of a 41-year-old male company worker whose brief psychosis was induced by a sensitivity training seminar held by the company he worked for is presented. In reviewing the psychopathology of the case with records from the ST seminar, we found similarities between the patient's ST seminar and brainwashing situations. Specifically, the patient experienced severe conflict (of thought process) between his Christian beliefs and being labeled a coward at the seminar. We conclude that monitoring of the ST programs is crucial in order to ensure the psychological safety of ST participants in Japan.

Adult↗
PubMed1996

A case of possessive state with onset influenced by 'door-to-door' sales.

Recently in Japan, 'door-to-door sales' has become of concern because it has created numerous legal and social problems. In this paper, a 47 year old dissociative trance disorder case who presented with possession by God is discussed. Specific types of door-to-door sales is known to use superstition and folk beliefs as tools to lure customers. In this particular case, these religious factors seemed to have played an important role in the precipitation of the disorder and its presentation. In addition, the brain-washing environment observed in video lectures used in door-to-door sales seemed to play an important role in the development of the possessive state. We also performed social psychiatric analysis of the occurrence of the possessive state in a city area, which has been considered to develop within traditional culture. Phenomenological classification by one of the authors was useful for diagnosing underlying disorders in the possessive state.

Adult↗
PubMed1996

Myocardial sympathetic dysinnervation in doxorubicin cardiomyopathy.

Single photon emission computed tomography (SPECT) using I-123 metaiodobenzylguanidine (MIBG) was evaluated for the detection of doxorubicin (DXR) cardiomyopathy in seven patients with malignant lymphoma receiving DXR doses ranging from 70 to 530 mg (DXR group), and 20 normal subjects without hypertension, diabetes mellitus or electrocardiographic abnormalities (control group). The ratio of the heart to mediastinal counts (H/M) and the washout rate (WR) in MIBG SPECT images were compared between the two groups. Correlation of total doses of DXR with H/M and the relationship of H/M to WR were investigated. The H/M of the DXR group was lower than that of the control group (3.00 +/- 0.97 vs 4.90 +/- 1.08, p < 0.001). The WR of the DXR group was higher than that of the control group (30.9 +/- 10.5% vs 16.5 +/- 9.1%, p < 0.001). Total DXR doses were inversely correlated with H/M (r = -0.86), H/M correlated inversely with the WR (r = -0.83) only in the DXR group. Pathological findings of one patient, who died of DXR cardiomyopathy, showed atrophic and fibrotic nerve fibers in the apical inferior segment of the left ventricle where MIBG uptake was reduced markedly. DXR cardiomyopathy can be detected with MIBG SPECT as cardiac sympathetic nervous dysinnervation. The pathological findings correspond to the MIBG SPECT findings.

3-Iodobenzylguanidine↗
PubMed1995

Cloning, expression, and chromosomal localization of a novel cadherin-related protein, protocadherin-3.

To study the diversity of the protocadherin family, the cDNA clones for a novel protocadherin were isolated by screening rat brain cDNA libraries with a cDNA fragment obtained by PCR, and some of the properties were then characterized. The overall structure of the protein defined by the clone is similar to that of previously identified protocadherins; however, the cytoplasmic domain is distinct from those of previously cloned protocadherins or any other protein sequences in the data bank. We named this protocad herin-3 (Pcdh3) since this is the third protocadherin of which the entire coding sequence has been determined. Most of the deduced amino acid sequences of other cDNA clones obtained by the screening show high homology with but are distinct from that of Pcdh3, indicating that most of these sequences correspond to homologous but different protocadherins. These results demonstrate that Pcdh3 and the protocadherins defined by these clones constitute a protocadherin subfamily. Chromosome mapping indicates that mouse Pcdh3 is located in a specific region of mouse chromosome 18, close to the location of previously cloned protocadherins, suggesting that various protocadherins form a cluster in this region. In situ hybridization results showed that Pcdh3 and its related proteins were expressed at various areas in brain. The expressed Pcdh3 protein from the cDNA in mouse L cells was about 100 kDa in molecular weight and was localized at cell-cell contact sites. In contrast to the classical cadherins, however, the expressed Pcdh3 was sensitive to trypsin even in the presence of Ca2+, and the transfectants did not show strong Ca(2+)-dependent cell aggregation activity. These results indicate the structural and possibly functional diversity of the protocadherin family and suggest a distinctive biological role for Pcdh3.

Amino Acid Sequence↗
PubMed1995

Molecular cloning and nucleotide sequences of the genes for two essential proteins constituting a novel enzyme system for heptaprenyl diphosphate synthesis.

The genes encoding two dissociable components essential for Bacillus stearothermophilus heptaprenyl diphosphate synthase (all-trans-hexparenyl-diphosphate:isopentenyl-diphosphate hexaprenyl-trans-transferase, EC 2.5.1.30) were cloned, and their nucleotide sequences were determined. Sequence analyses revealed the presence of three open reading frames within 2,350 base pairs, designated as ORF-1, ORF-2, and ORF-3 in order of nucleotide sequence, which encode proteins of 220, 234, and 323 amino acids, respectively. Deletion experiments have shown that expression of the enzymatic activity requires the presence of ORF-1 and ORF-3, but ORF-2 is not essential. As a result, this enzyme was proved genetically to consist of two different protein compounds with molecular masses of 25 kDa (Component I) and 36 kDa (Component II), encoded by two of the three tandem genes. The protein encoded by ORF-1 has no similarity to any protein so far registered. However, the protein encoded by ORF-3 shows a 32% similarity to the farnesyl diphosphate synthase of the same bacterium and has seven highly conserved regions that have been shown typical in prenyltransferases (Koyama, T., Obata, S., Osabe, M., Takeshita, A., Yokoyama, K., Uchida, M., Nishino, T., and Ogura, K. (1993) J. Biochem. (Tokyo) 113, 355-363).

Alkyl and Aryl Transferases↗
PubMed1995

Four ferredoxins from Japanese radish leaves.

We detected three ferredoxin components, a, b, and c, in green shoots of Japanese radish seedlings by hydrophobic HPLC analysis using a phenyl-5PW column. All components were also present in mature leaves. Component a was further separated into two components, a1 and a2, by reversed-phase HPLC after carboxymethylation. The existence of four ferredoxins in the photosynthetic tissue of a single plant species is reported here for the first time. Each individual ferredoxin component was isolated, and its primary structure was analyzed for comparison with the two leaf ferredoxins, L-Fds A and B, isolated by Wada et al. (J. Biochem. 105, 619-625 (1989)). The primary structures of components a1, a2, and b were all found in 12 possible structures of L-Fd A deducible from its microheterogeneities. This led us to conclude that L-Fd A is a mixture of three ferredoxins corresponding to components a1, a2, and b. The complete primary structure of component c was established by sequencing of the whole protein and of peptides generated by protease digestion. The N-terminal structure of component c was identical with L-Fd B up to the 11th amino acid residue, suggesting that this component is the same ferredoxin as L-Fd B.

Amino Acid Sequence↗
PubMed1995

Protocadherin Pcdh2 shows properties similar to, but distinct from, those of classical cadherins.

Cell adhesion and several other properties of a recently identified cadherin-related protein, protocadherin Pcdh2, were characterized. A chimeric Pcdh2 in which the original cytoplasmic domain was replaced with the cytoplasmic domain of E-cadherin was expressed in mouse L cells. The expressed protein had a molecular mass of about 150 kDa and was localized predominantly at the cell periphery, as was the wild-type Pcdh2. In a conventional cell aggregation assay, the transfectants showed cell aggregation activity comparable to that of classical cadherins. This activity was Ca(2+)-dependent and was inhibited by the addition of anti-Pcdh2 antibody, indicating that the chimeric Pcdh2, and probably the wild-type Pcdh2, has Ca(2+)-dependent cell aggregation activity. Mixed cell aggregation assay using L cells and different types of transfectants showed that the activity of Pcdh2 was homophilic and molecular type specific and that Pcdh2 was transfectants did not aggregate with other types of transfectants or with L cells. In immunoprecipitation, the chimeric Pcdh2 co-precipitated with a 105 kDa and a 95 kDa protein, whereas wild-type Pcdh2 co-precipitated with no major protein. Pcdh2 was easily solubilized with non-ionic detergent, in contrast to the case of classical cadherins. On immunofluorescence microscopy, the somas of Purkinje cells were diffusely stained with anti-human Pcdh2 antibody. Mouse Pcdh1 and Pcdh2 were mapped to a small segment of chromosome 18, suggesting that various protocadherins form a gene cluster at this region. The present results suggest that Pcdh2, and possibly other protocadherins as well as protocadherin-related proteins such as Drosophila fat, mediate Ca(2+)-dependent and specific homophilic cell-cell interaction in vivo and play an important role in cell adhesion, cell recognition, and/or some other basic cell processes.

Animals↗
PubMed1995

[Stereotactic radiation therapy with linear accelerator: accuracy of alignment and portal film verification].

Stereotactic radiation therapy with a linear accelerator requires precise alignment of therapeutic radiation distribution to the target volume. To verify the accuracy of alignment, differences between the stereotactic coordinates of the center of the therapeutic radiation distribution determined from portal films and those of the target points determined from CT/MRI or CT/angiographic localization were calculated for 58 points. The average values and one standard deviation were--0.02 +/- 0.50mm, 0.37 +/- 0.39mm and 0.01 +/- 0.25mm in the x, y, and z directions, respectively. The average value of the total deviation was 0.73 +/- 0.07mm. Potential sources of misalignment were misaligned laser pointers, wide laser beam width, improperly zeroed target positioner scale, and motion of the patient couch. The accuracy of alignment should be verified prior to irradiation. Portal film verification is indispensable for strereotactic radiation therapy with a linear accelerator.

Cranial Irradiation↗
PubMed1995

[Indications for chest CT: retrospective study of cases with normal chest CT].

The usefulness of computed tomography (CT) in thoracic radiology is now well appreciated, and the number of chest CTs has greatly increased. There are, however, many chest CT cases that are completely or almost completely normal. Indications for chest CT should be re-evaluated considering the cost and radiation exposure associated with the examination. Reviewing the reports of 4930 chest CT examinations performed in three hospitals during the period of two years, the author found 620 (12.6%) negative CT examinations. In 312 of the 620, the CT was requested because of "abnormal shadow" on chest radiograph. When the same chest radiographs were re-evaluated by two radiologists, no abnormality was noted in 257 cases (82.4%). CT examinations were considered justified in only 55 cases (17.6%). There was a significant difference in the frequency of normal chest CT examinations between the university hospital and two other hospitals. The causes of false positive interpretation of chest radiographs were analyzed, and it was felt that fundamental knowledge necessary to interpret chest radiographs was lacking. The importance of close cooperation between clinicians and radiologists should be emphasized.

Adolescent↗
PubMed1995

Use of strip biopsy for early duodenal cancer--a case report.

A 67-year-old man was referred for investigation of an abdominal mass. Upper gastrointestinal endoscopy revealed a polypoid lesion with a central depression in the duodenum. CT scan demonstrated a cystic lesion anterior to the pancreas. Examination of a biopsy specimen of the duodenal lesion suggested it was a carcinoma. Strip biopsy was therefore performed, and histological examination revealed a tubular adenocarcinoma with invasion limited to the mucosa, indicating that the lesion was completely resected. Subsequent 24-month follow-up did not indicate recurrence of the cancer. Strip biopsy thus appears to be a safe and efficient procedure for the management of early duodenal cancer.

Adenocarcinoma↗
PubMed1994

Structural and functional roles of the cysteine residues of Bacillus stearothermophilus farnesyl diphosphate synthase.

p-(Chloromercuri)benzoic acid inhibited the catalytic activity of Bacillus stearothermophilus farnesyl diphosphate synthase (FPP synthase), which contains only two cysteine residues at positions 73 and 289. In order to explore the role of the cysteine residues, either or both of them were replaced with phenylalanine or serine. Five mutant enzymes, C73F, C73S, C289F, C289S, and C73S-C289S, were overproduced in Escherichia coli and purified to homogeneity. All of them were active as farnesyl diphosphate synthase, showing specific activities comparable to that of the wild-type enzyme. These results indicate that neither of the cysteines is essential for catalytic function. The C73F mutant, however, was very sensitive to heat treatment, while C73S was as highly stable as the wild type. The Km value of C289F for isopentenyl diphosphate is 10 times that of the wild type. The wild-type enzyme was converted into an oxidized form which was separable from the native enzyme on ion-exchange chromatography, and this conversion was accelerated by cupric ions. Similar conversion has previously been reported by several researchers, who found the occurrence of two forms of pig liver FPP synthase and who attributed this phenomenon to the oxidoreduction of sulfhydryl and disulfide groups. However, even the C73S-C289S mutant, which has no cysteine residues, was also converted into an oxidized form as in the case of the wild-type enzyme. These results provide evidence that residues other than cysteine are involved in the conversion of this enzyme into the oxidized form.

Alkyl and Aryl Transferases↗
PubMed1994

Primary malignant fibrous histiocytoma of the diaphragm: report of a case.

We present herein the case of a 55-year-old man with primary malignant fibrous histiocytoma (MFH) of the diaphragm. He was admitted to our hospital with right anterior chest pain, where diagnostic imaging showed a huge tumor in the right diaphragm with a tumor thrombus in the vena cava, spreading to the left lobe of the liver and the pericardium. Although invasion into the right lung was identified at the time of surgery, the entire tumor was removed. Histopathological examination of the resected specimen revealed the characteristics of MFH. We discuss the clinical features of this patient in comparison with the few previous reports on MFH of the diaphragm.

Diagnostic Imaging↗
PubMed1994

Characterization of cadherin-4 and cadherin-5 reveals new aspects of cadherins.

Several properties of cadherin-4 and cadherin-5 were characterized by using the cDNA transfection approach. The proteins of both cadherins had a relative molecular mass of about 130 kDa and were present at the cell periphery, especially at cell-cell contact sites. These cadherins were easily digested with trypsin, and Ca2+ protected cadherin-4, but not cadherin-5, from the digestion. In immunoprecipitation, cadherin-4 co-precipitated with two major proteins of 105 kDa and 95 kDa, respectively. The 105 kDa and the 95 kDa proteins are likely to correspond to alpha- and beta-catenins. Cadherin-5 co-precipitated with only one major protein of 95 kDa, but seems to associate with the 105 kDa protein. On the other hand, plakoglobin or gamma-catenin did not co-precipitate well with either cadherin-4 or cadherin-5 in immunoprecipitation, but plakoglobin also appears to associated weakly with these cadherins. Cadherin-4 transfectants aggregated within 30 minutes in a cell aggregation assay, but cadherin-5 transfectants did not aggregate under the same conditions. Furthermore, the transfectants of chimeric cadherin-4 with cadherin-5 cytoplasmic domain showed cell aggregation activity comparable to that of wild-type cadherin-4 transfectants, whereas the transfectants of chimeric cadherin-5 with cadherin-4 cytoplasmic domain did not show appreciable cell aggregation, suggesting that the extracellular domains of cadherins, in conjunction with their cytoplasmic domains, play an important role in cell aggregation activity. These results show that cadherin-4 is very similar to the classical cadherins, whereas cadherin-5 is functionally as well as structurally distinct from classical cadherins.

Animals↗
PubMed1994

Observation of sleep-related breathing disorders in patients with coronary artery disease by ambulatory electrocardiogram-respiration monitoring system.

Eighty-five coronary artery patients examined using an ambulatory electrocardiogram-respiration monitoring system (AERMS) in which a respiratory sensor was strapped to the right upper abdominal wall. Apnea was defined as a cessation of abdominal wall movement lasting at least 10 sec. Sleep-related breathing disorder (SRBD) was diagnosed if at least 30 apneic episodes were observed during sleep. The cardiac events evaluated during follow-up included occurrence of sudden death, myocardial infarction and ventricular tachycardia. SRBD was detected in 9 of 85 patients (11%). There were more patients with low EF (EF < 50%) in the SRBD group than in the non-SRBD group (p < 0.01). During follow-up for a mean period of 18.4 +/- 7.6 months after ambulatory recording, four of nine (44%) patients in the SRBD group had cardiac events, compared with only four of 79 (6%) patients in the non-SRBD group (p < 0.001). Thus, coronary artery patients who were complicated with SRBD showed poor cardiac function and had a high incidence of cardiac events.

Aged↗
PubMed1994

Thermostable farnesyl diphosphate synthase of Bacillus stearothermophilus: crystallization and site-directed mutagenesis.

The gene for thermostable farnesyl diphosphate synthase from Bacillus stearothermophilus was cloned, sequenced, and overexpressed in Escherichia coli. The synthase was purified to homogeneity and crystallized. The enzyme carried only two cysteine residues in contrast to its counterparts from other sources, which have four to six cysteine residues. Either or both of the cysteine residues can be replaced with serine without causing a loss of the catalytic activity. The conserved arginine residue that occupies the third position from the C-terminus was also replaced with valine without significant loss of activity, but the valine mutant showed a weakened affinity for isopentenyl diphosphate.

Amino Acid Sequence↗