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Biomedical subjects

M Koyama

Publications and source records attributed to M Koyama.

At least 145 records · Page 8Linked to original sources
PubMed1995

The novel variants of mb-1 and B29 transcripts generated by alternative mRNA splicing.

The Ig-alpha/Ig-beta heterodimers encoded by mb-1 and B29 genes, respectively, are crucial for the constitution of the B-cell receptor (BCR). We report here novel variants of mb-1 and B29 transcripts produced by alternative mRNA splicing. The proteins encoded by these variants are predicted to conserve transmembrane and cytoplasmic portions of Ig-alpha and Ig-beta but lack a part of the extracellular portions containing cysteine residues which are required for intramolecular and intermolecular S-S bonds. Transfection studies revealed that the variant mb-1 and B29 did not contribute to the BCR expression on cell surfaces. Although peripheral B cells contain small amounts of the variant mb-1 and B29 transcripts, treatment with an anti-IgM antibody, LPS or IL-4 induces a significant increase in amounts of the variant transcripts. These observations suggest that B-cell activation induces alternative splicing of mb-1 and B29 transcripts which encode proteins unable to constitute the BCR.

Alternative Splicing↗
PubMed1995

Intussusception of the appendix: a report of three cases with different clinical and pathologic features.

Three cases of intussusception of the appendix (IA) with distinctive pathologic changes were reported. All patients were women with different clinical presentations. Grossly, a complete intussusception was found in one case (case 1), while the others (cases 2 and 3) showed a partial intussusception. In case 1, almost the total segment of the appendix bearing the villous adenoma with focal malignant transformation became completely telescoped into the cecum. In case 2, no underlying appendiceal lesion was disclosed. In case 3, appendiceal endometriosis was found as the point of traction. Awareness of such a rare complication associated with various appendiceal lesions provides a clue for making an accurate diagnosis and selecting appropriate surgical management.

Abdominal Pain↗
PubMed1995

Non-X histiocytoma, similar to fibrous histiocytoma, in an infant.

A case is presented of a female infant with an atypical histiocytoma. A gradually enlarging brown lesion was noted on the left side of the chest at the age of 2 weeks. Microscopic study of a biopsy revealed an ill-defined infiltration of spindle cells with indented nuclei. The tumor cells were positive for CD14, HLA-DR, lysozyme, alpha-1-antitrypsin and alpha-1-antichymotrypsin, and negative for CD1, CD3, CD8, CD10, CD19, CD68 and S-100 by immunohistochemistry. Electron microscopy demonstrated no distinct Birbeck's granules, but aberrant granules were seen in a small number of cells. At 7 months of age, a nodule with similar histologic features was noted in the nuchal region, but was incompletely resected. The patient remains recurrence-free at 36 months of age. This case is thought to be a benign form of non-X histiocytoma.

Diagnosis, Differential↗
PubMed1995

Regulation of classical HLA class I genes in human choriocarcinoma cells by nuclear proteins binding to MHC class I regulatory elements.

PROBLEM: The regulation of classical HLA class I genes in choriocarcinoma have been reported. METHODS: We determined whether four choriocarcinoma cell lines expressed classical HLA class I or HLA-G by a reverse transcription-polymerase chain reaction (RT-PCR) and studied the regulatory mechanism of classical class I using a gel mobility shift assay. RESULTS: NUC1 and SCH expressed classical class I but not HLA-G. GCH1 and Jar did neither. Nuclear protein binding to the class I regulatory element (CRE) was detected in NUC1 and SCH. Interferon-gamma augmented both classical class I expression and the DNA-protein complex in NUC1. The DNA-protein complex was not observed in GCH1, and Jar showed a CRE-binding protein with different electrophoretic mobility and binding affinity from that of SCH and NUC1. CONCLUSION: The CRE is one of the regulatory elements of classical HLA class I genes in choriocarcinoma cells.

Base Sequence↗
PubMed1995

Surgical treatment of mesenteric infarction, thoracoabdominal aortic aneurysm, and proper hepatic aneurysm in a middle-aged woman with Takayasu's arteritis.

Although Takayasu's arteritis may present a wide variety of signs and symptoms depending on the vessel affected, it is rarely associated with acute abdomen requiring emergency laparotomy. We report a case of Takayasu's arteritis that required several surgical interventions for mesenteric infarction, thoracoabdominal aneurysm, and proper hepatic artery aneurysm, all of which were noted in succession within a 1-year period. This is also the first report, to our knowledge, of a hepatic artery aneurysm caused by Takayasu's arteritis.

Abdomen, Acute↗
PubMed1995

[A new 3-dimensional head fixation device for brain imaging].

We have developed a new head fixation device for studies of brain function. This device was designed to immobilize subject's heads during image scanning and to precisely reproduce the head position for two different imaging modalities such as MRI and PET. The device consists of a plastic frame, a pillow filled with beads of styrene foam, and a face mask of thermoplastic resin which was originally intended for application in radiotherapy. A bridge for biting was incorporated into the mask for stable fixation. The device enables immobilization of subject's heads with good reproducibility of position at the practical level. Our results indicate that this head fixation system is useful for fixation of head during activation studies using PET.

Brain↗
PubMed1995

[Usefulness of adjuvant chemotherapy with antimetabolites for cervical invasive cancer].

A series of 584 patients with cervical invasive cancer were included in the retrospective study on the efficacy of long-term oral maintenance chemotherapy with antimetabolites (Fluorouracil or Tegaful). The patients were histologically classified into the squamous cell carcinoma (SCC) group and the adenocarcinoma (AD) group. In the SCC group (n = 518), 163 patients were given more than 300 mg/day of antimetabolite tablets for one year or more after the main therapy (hysterectomy or pelvic irradiation). In the AD group (n = 66), 36 patients were treated with the same dose of antimetabolites. The Kaplan-Meier overall and cancer specific survival analysis estimates that the chronic administration of antimetabolites did not improve the cumulative 5-year survival in the SCC group. In contrast, the cumulative 5-year survival rate in the AD group treated with antimetabolites (88%) was significantly higher than that without chemotherapy (64%) by Kaplan-Meier analysis. This significant improvement in the survival rate in the AD group due to antimetabolites was notable in patients in FIGO stage I or II treated with radical or semiradical hysterectomy, these results indicate that oral adjuvant chemotherapy with antimetabolites is useful for cervical adenocarcinoma, but not for squamous cell carcinoma.

Adenocarcinoma↗
PubMed1995

[Clinical usefulness of 201Tl-chloride scintigraphy for the diagnosis of bone metastases].

Fifty-five patients with bone lesions underwent 201Tl-chloride (201TlCl) scintigraphy to evaluate its findings and usefulness for the diagnosis of bone metastases. 201TlCl scintigraphy was performed 15 minutes (early scan) and 2 hours (delayed scan) after intravenous administration of 5.55 MBq/kg of 201Tl-chloride. To evaluate the degree of tracer retention at the lesions, we calculated retention index after setting regions of interest in each lesions demonstrated tracer uptake in both early and delayed scans. Among 118 lesions of pathologically and/or clinically confirmed bone metastases, 201TlCl planar images disclosed 90 (76.3%) and 88% (74.6%) lesions on early and delayed scans, respectively. SPECT images were preferable for the evaluation of the lesions in the spine, the thoracic cage and pelvis. Correlation of tumor size with findings on 201TlCl images demonstrated 90.5% sensitivity for the metastases more than 7 cm3. No correlational difference was seen in the sensitivity depending on primary cancers. The overall retention index of bone metastases was -21.4 +/- 47.1. Bone metastases of pulmonary adenocarcinomas and small cell carcinomas demonstrated higher retention index than those of pulmonary squamous cell carcinomas and breast cancers. On 201TlCl images, no abnormal tracer uptakes were seen in benign lesions detected by 99mTc-hydroxymethylene diphosphonate (99mTc-HMDP) images except 5 lesions. The retention index of these benign lesions demonstrated abnormal uptakes on 201TlCl images was -48.3 +/- 15.0, which found no significant difference between that of metastases. In cases of vertebral compression fractures, abnormal tracer uptakes were demonstrated in 9 of the 12 pathologic fractures against 2 of the 10 benign ones. Those 2 benign fractures proved to be vertebral tuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Cerebral blood flow measurement with iodine-123-IMP SPECT, calibrated standard input function and venous blood sampling.

UNLABELLED: We previously reported simple methods for measuring cerebral blood flow (CBF) with 123l-labeled N-isopropyl-p-iodoamphetamine (IMP) and SPECT: table look-up method and autoradiography. With these methods, the arterial input function is obtained by calibrating the standard input function using one-point arterial blood sampling 10 min after IMP infusion. In this study, we sought to determine if these approaches can be as successful when used with venous blood sampling. METHODS: After IMP infusion, simultaneous arterial and venous blood samples were drawn from 30 subjects without heart or lung disease. RESULTS: The activity ratios of venous whole blood from the cubital vein to arterial blood were 0.75 +/- 0.09, 0.77 +/- 0.10, 0.78 +/- 0.03 and 0.83 +/- 0.11, respectively, at 10, 20, 30 and 50 min after IMP infusion. Venous blood activities were always 20% lower than the artery values over 50 min. When blood was sampled from the dorsal hand vein, however, the respective ratios were 0.92 +/- 0.03, 0.93 +/- 0.05, 0.97 +/- 0.04 and 0.98 +/- 0.08 after 10, 20, 30 and 50 min. Furthermore, when the palm was exposed to heat during the sampling period, blood activity levels increased to 0.92 +/- 0.04, 0.96 +/- 0.04, 0.99 +/- 0.05 and 0.98 +/- 0.03. Thus, venous blood activities were consistent with arterial activity, presumably because of the numerous arteriovenous anastomoses in the palm. Optimal times for venous blood sampling, with and without palm heating, were determined by error analysis to be 15 and 20 min, respectively, after IMP infusion. CONCLUSION: Venous blood sampling from the dorsal hand can be substituted for arterial blood sampling in IMP-CBF studies.

Amphetamines↗
PubMed1995

[Normal cerebral perfusion of 99mTc-HMPAO brain SPECT--evaluation by ananatomical standardization technique].

Single photon labeled tracer 99mTc-hexamethylpropylene amine oxime (HMPAO) has been used for rCBF studies by SPECT. However, normal perfusion pattern of this agent still remains unclear. The purpose of this study was to investigate normal 99mTc-HMPAO SPECT image voxel by voxel. Eighteen male subjects without any prior or present history of medical illness participated in this study. All SPECT images were globally normalized to 100 count/voxel. Each subject had an X-ray CT scan at the same day of SPECT measurement. All subjects had normal X-ray CT scans. The standard anatomical structures of the computerized brain atlas of Roland et al. were fitted to X-ray CT images of a subject by linear and non-linear parameters. These parameters were subsequently used to transform SPECT images of the subject. After the anatomical standardization, mean and SD images of eight standardized images were calculated voxel-by-voxel basis. In the mean image, following structures showed relatively higher radioactivity; the putamen, the cerebellum, and the frontal lobe. In addition, the occipital lobe, parietal lobe, frontal lobe, and the putamen showed large degree of SD. Anatomical standardization of SPECT images may be useful as a reference to diagnose and evaluate various brain disorders.

Adult↗
PubMed1995

Production of platelet-activating factor by porcine brain microvascular endothelial cells in culture.

Endothelial cells produce platelet-activating factor (PAF), which is the key process in the interactions between the vascular wall and blood cells. To examine the production of PAF in brain microvasculature we have cultured brain endothelial cells and performed a comparative study with aortic endothelial cells. Fresh porcine brain was homogenized, and microvascular endothelial cells were separated by enzyme digestion. The cells were cultured in medium containing epidermal growth factor and bovine brain extract. Endothelial cells from the aorta of the same animal were cultured in a similar manner. Production of PAF was assessed by [3H]acetate incorporation into phospholipids or by radioimmunoassay. Prostacyclin was measured by radioimmunoassay of 6-ketoprostaglandin F 1 alpha. The cells produced 1760 +/- 403 and 2892 +/- 347 dpm/10(6) cells (n = 4) of PAF when stimulated with bradykinin and calcium ionophore A23187, each at 1 microM, respectively. Aortic endothelial cells produced 3911 +/- 2006 and 8052 +/- 2270 dpm/10(6) cells (n = 4), respectively, and these values were significantly higher than those in brain endothelial cells (p < 0.01, U-test). Prostacyclin production was also higher in aortic cells as compared to brain microvascular endothelial cells. In aortic endothelial cells both Ca ionophore A23187 and bradykinin significantly stimulated PMN adherence whereas in brain microvascular cells only Ca ionophore enhanced the adherence. Brain microvascular endothelial cells produce smaller amount of PAF and prostacyclin as compared to aortic endothelial cells, and this fact may imply that the functional integrity of the brain microvascular endothelium is maintained at a low level.

Animals↗
PubMed1995

[The content and its teaching method of nursing for the elderly in baccalaureate program].

PURPOSE: The study is intended to examine the content of gerontological nursing for the baccalaureate program in nursing and to review its teaching methods. METHODS: Articles and books were reviewed extensively, information was gathered from various gerontological health professionals and family caregivers were interviewed, and a survey was conducted by questionnaire on the students' views of the elderly people. RESULTS: The contents of gerontological nursing education included features of the elderly, trends of social situations for the elderly and characteristics of the gerontological nursing approach. Features of the elderly mean a comprehensive understanding of the elderly including physical, psychological and social aspects. Characteristics of gerontological nursing included assistance for the elderly, assistance for families, and intervention for the organization which supports the elderly. In providing assistance to the elderly, it is necessary to be sensitive and to respect their life, independence, dignity, and relation with society. The teaching method of gerontological nursing education should be organized according to the principles of learning, that is, from familiar subjects to unknown subjects, and from simple to complicated ones. For future study, a detailed examination of the contents and methods of gerontological nursing education is needed.

Curriculum↗
PubMed1994

A Clostridium perfringens vector for the selection of promoters.

A promoter selection vector for Clostridium perfringens genes was constructed from a C. perfringens-Escherichia coli shuttle vector, pJIR418. The plasmid carries a promoterless chloramphenicol acetyltransferase gene (catP), derived from pIP401, downstream of the multiple cloning sites of pUC18. When a promoter region of the phospholipase C gene was inserted into one of the cloning sites, derivatives of C. perfringens strain 13 carrying the resultant plasmid acquired resistance to chloramphenicol. This plasmid should be useful reporter system for C. perfringens genes.

Base Sequence↗
PubMed1994

Density-associated changes in platelet-activating factor acetylhydrolase activity and membrane fluidity of human erythrocytes.

Platelet-activating factor acetylhydrolase is known to degrade oxidatively fragmented phospholipids which are similar in structure to platelet-activating factor. We examined changes of acetylhydrolase activity during in vivo aging of human erythrocytes and tried to assess its role in maintaining the membrane properties of erythrocytes. Higher-density erythrocytes are enriched with older cells. Erythrocytes obtained from seven healthy colleagues were separated into four density fractions by centrifugation in discontinuous Percoll density gradients. Both membrane and cytosolic acetylhydrolase decreased with increasing erythrocyte density. Membrane and cytosolic acetylhydrolase activities in the lightest fraction were 2.0 +/- 1.0 (SD) nkat/g protein and 362 +/- 58 pkat/g protein, respectively, and these values were significantly higher than those in the densest fraction: 1.3 +/- 0.7 nkat/g protein and 286 +/- 70 pkat/g protein, respectively. Membrane acyltransferase activity also decreased with red cell density and the average values in the lightest and densest fractions were 51.2 +/- 23.6 and 27.0 +/- 20.2 mukat/g protein, respectively. Generation of thiobarbituric acid-reactive substances induced by t-butyl hydroperoxide treatment decreased with increasing cell density, and the inhibition of acetylhydrolase with diisopropylfluorophosphate resulted in enhanced peroxide-induced lipid oxidation, particularly in lower-density fractions. There was no significant change in basal levels of thiobarbituric acid-reactive substances in red cell membrane. Membrane fluidity was evaluated by fluorescence recovery after photo-bleaching and it decreased as erythrocyte density increased. We conclude that the activity of the deacylation/reacylation cycle maintained by acetylhydrolase and acyltransferase is gradually reduced during in vivo aging of erythrocytes. This may be connected with decreases of polyunsaturated fatty acids and membrane fluidity in old erythrocytes.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1994

Loss of biological activity of human chorionic gonadotropin (hCG) by the amino acid substitution on the "CMGCC" region of the alpha-subunit.

In order to study the bioactive sites of the glycoprotein hormones, we have prepared five point mutants on the CMGCC (Cys28-Met29-Gly30-Cys31-Cys32) region of the human alpha-subunit by using site-directed mutagenesis. Each mutant human chorionic gonadotropin (hCG) agr; cDNA and a wild-type hCG beta cDNA were transcribed by T3 RNA polymerase, and the mixture of the hCG alpha mRNA and hCG beta mRNA was microinjected into Xenopus laevis oocytes. All five mutant hCGs produced in oocyte culture supernatants were detected as immunoreactive forms by enzyme immunoassay. In contrast, four mutants (Cys28-->Tyr28, Gly30-->Arg30, Ala30, Asp30) were devoid of biological activity in vitro bioassay using the production of testosterone with mouse Leydig cells. These results indicate that the CMGCC region in the alpha-subunit, particularly the cysteine residue at position 28 and the glycine residue at position 30, plays an important role in the biosynthesis of glycoprotein hormones.

Amino Acid Sequence↗