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Biomedical subjects

M Oshima

Publications and source records attributed to M Oshima.

At least 127 records · Page 7Linked to original sources
PubMed1994

Major defect of carbohydrate-deficient-glycoprotein syndrome is not found in the synthesis of dolichyl phosphate or N-acetylglucosaminyl-pyrophosphoryl-dolichol.

The contents of dolichyl phosphate and UDP-N-acetylglucosamine:dolichyl phosphate N-acetylglucosamine 1-phosphate transferase (GlcNAc-1-P transferase) activity in fibroblasts from patients with carbohydrate-deficient-glycoprotein (CDG) syndrome were analyzed. The amount of dolichyl phosphate and GlcNAc-1-P transferase activity in CDG syndrome fibroblasts were similar to those in normal fibroblasts, suggesting that CDG syndrome may not be due to a deficiency of a biosynthetic enzyme for dolichol-oligosaccharide intermediates, but to a metabolic error in assembly of asparagine-linked oligosaccharide.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1994

Fucosyltransferase-producing sialyl Le(a) and sialyl Le(x) carbohydrate antigen in benign and malignant gastrointestinal mucosa.

BACKGROUND: Sialyl Le(a) antigen and sialyl Le(x) antigen are cancer-associated carbohydrate antigens. Previous immunohistologic and immunochemical studies have shown that these antigens are preferentially expressed in gastric cancer and colonic cancer and that they possibly are related to the metastatic potential of the cancer cells. The biosynthesis of these antigens is completed by fucosyltransferases, but it has not been reported how fucosyltransferases control the expression of these carbohydrate antigens concerning the invasive potential of the cancer. METHODS: The authors established an assay system for measuring the activity of alpha 1-->4 fucosyltransferase (sialyl Le(a) synthase) and alpha 1-->3 fucosyltransferase (sialyl Le(x) synthase) with a high-pressure liquid chromatography system (HPLC). The activity was measured in various parts of normal and cancerous gastric and colonic tissue and compared with the expression of sialyl Le(a), sialyl Le(x), Le(a), and Le(x) antigens determined in a solid-phase enzyme-linked immunosolvent assay (EIA). RESULTS: Sialyl Le(a) synthase was detected in most normal or malignant mucosa of gastric and colonic tissues, regardless of anatomic locations. Sialyl Le(x) synthase activity generally was low in the normal gastric mucosa, whereas the activity was higher in 77% (7 of 9) of gastric cancer tissues than in corresponding normal tissues with enhanced expression of sialyl Le(x) antigen in most patients (5 of 7). In the large intestine, the activity of sialyl Le(a) synthase and sialyl Le(x) synthase was correlated. Although enhanced expression of sialyl Le(x) in colonic cancer was observed in 86% (12 of 14) of all patients, concomitant higher sialyl Le(x) synthase activity than that in normal tissue was observed in only 58% (7 of 12) of patients. CONCLUSIONS: The expression of sialyl Le(a) and sialyl Le(x) antigens in the stomach and the colon was not controlled solely by fucosyltransferases but by a more complicated system involving other glycosyltransferases.

Adenocarcinoma↗
PubMed1994

Sequential microanalyses of free dolichol, dolichyl fatty acid ester and dolichyl phosphate levels in human serum.

Sequential microanalyses of free dolichol, dolichyl fatty acid ester and dolichyl phosphate in human serum were made. To determine the level of each dolichol, samples were pretreated using three different methods prior to fluorescent derivatization. To estimate the concentrations of free dolichol, samples were added to alkaline methanol and kept at room temperature for 1 h. In case of dolichyl fatty acid ester, samples were saponified at 100 degrees C for 1 h. To estimate dolichyl phosphate, saponified lipid extracts were treated with acid phosphatase. Each pretreated dolichol was reacted with anthracene-9-carboxylic acid and amounts of 9-anthroyl derivatives were determined fluorometrically by HPLC. This method is simple and three types of dolichols can be estimated using the same HPLC system. This analysis is also sufficiently sensitive for measurement of serum dolichol levels. The contents of free dolichol, dolichyl fatty acid ester and dolichyl phosphate in human serum were found to be 44.9 +/- 10.5 ng/ml (n = 32), 76.4 +/- 24.2 ng/ml (n = 32) and 43.5 +/- 15.1 ng/ml (n = 13), respectively. These levels had apparently no correlation to age or serum total cholesterols. A linear correlation between dolichols and high-density lipoprotein cholesterols reflects the fact that the dolichols are associated with the high-density lipoprotein fraction.

Chromatography, High Pressure Liquid↗
PubMed1994

The long-term down-regulation of dihydropyridine receptors by Bay K 8644 in PC12 cells.

Treatment of PC12 cells with Bay K 8644 for 12 hr or more leads to an almost 80% decrease in the subsequent ability of Bay K 8644 to stimulate the uptake of radioactive calcium into the cells. This effect is a property of the S(-)isomer of Bay K 8644; pre-treatment with the R(+)isomer, now known to be a calcium channel blocker, has the opposite effect. This treatment is specific in that it does not interfere with the stimulation of calcium uptake by potassium, ATP, or nerve growth factor. Such treatment is accompanied by a 90% decrease in the ability of Bay K 8644 to stimulate the release of norepinephrine. The characteristics of the binding of [3H]isradipine to control and to treated cells indicates that the decrease in the effect of dihydropyridines is accompanied by a marked decrease in the number of dihydropyridine binding sites with no apparent change in the affinity of the remaining sites. The continued ability of depolarizing levels of potassium to stimulate calcium uptake and the induction of the protooncogene c-fos in Bay K 8644-treated cells indicates that the L-type calcium channels are still intact, but are simply unresponsive to dihydropyridine agonists.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Churg-Strauss syndrome (allergic granulomatous angiitis) with multiple perforating ulcers of the small intestine, multiple ulcers of the colon, and mononeuritis multiplex.

A case of Churg-Strauss syndrome with multiple perforations of the small intestine is described. A 31-year-old woman was admitted with a complaint of epigastric pain. She had a history of bronchial asthma. One week before admission, white blood cell count was 20,800/mm3 with 59% eosinophils. Neurological examination on admission disclosed mononeuritis multiplex with paresthesia in both the lower and upper extremities. At colonoscopy, there were scattered aphthous ulcers in the colon. Ophthalmological examination revealed allergic conjunctivitis. After admission, hypereosinophilia increased to as high as 36,000/mm3. Oral administration of prednisolone (60 mg/day) was begun. On the 3rd day of the treatment, the eosinophil count decreased dramatically, to 400/mm3, while severe abdominal pain developed. Since abdominal X-ray film revealed free air in the abdominal cavity, emergency laparotomy was performed and multiple intestinal ulcers with perforations were found. Partial ileectomy was performed. Pathological findings of the resected specimen were interpreted as a necrotizing angiitis with extravascular granuloma. Since the operation, the patient has been asymptomatic, except for neurological symptoms. Hypereosinophilia has decreased without treatment to counts averaging 270/mm3, within 3 months. On the basis of the clinical features and histopathological findings, a diagnosis of Churg-Strauss syndrome was established.

Adult↗
PubMed1994

Profile of the regions of acetylcholine receptor alpha chain recognized by T-lymphocytes and by antibodies in EAMG-susceptible and non-susceptible mouse strains after different periods of immunization with the receptor.

C57BL/6 (B6) mice develop a neuromuscular disease, experimental autoimmune myasthenia gravis (EAMG), after two or more immunizations with Torpedo californica acetylcholine receptor (AChR). To determine whether EAMG is related to recognition of particular region(s) on the main extracellular domain of the alpha chain (residues alpha 1-210) in prolonged immunization, we have examined the differences in the antibody and T cell recognition profiles of B6 and SJL (a strain that does not develop EAMG) mice after different periods and a number of immunizations with Torpedo AChR. In a given strain, antibodies and T cells recognized immunodominant regions, which may coincide or may be uniquely B cell or T cell determinants. Both B6 and SJL exhibited similar antibody recognition profiles after the second and through the fourth immunizations with AChR. Major differences between the two strains were found in their T cell recognition of regions in the second part (residues 100-210) of the main extracellular domain of the alpha chain. T cells of SJL recognized consistently only one region (111-126) within this part of the alpha chain, whereas in B6, T cell recognition of three peptides (111-126, 146-162 and 182-198) and next neighbor regions to them persisted throughout the period. Of these three peptides, 146-162 was an immunodominant peptide unique to B6, as the other two peptides (111-126 and 182-198) were also recognized by either T cells or antibodies in SJL. To study the role of the T cells recognizing region 146-162 in EAMG, a T cell line was generated against this region and the cells transferred into B6 mice followed by one Torpedo AChR injection. Enhancement of antibody production toward alpha chain peptides was observed as an influence of T cell transfer compared to profiles at 1 week. In addition, one out of three mice examined showed signs of EAMG. These results suggest the importance of T cells recognizing residues 146-162 in EAMG. It is concluded that the presence of persistent T cell responses to the second half (residues (100-210) of the main extracellular domain of the alpha chain is associated with the development of EAMG in B6 mice, while absence of these responses in SJL mice may enable them to escape the disease. The preservation of the immunodominance of peptide 146-162 in the T cell recognition of B6 is probably most important for the pathogenesis of EAMG in this strain.

Amino Acid Sequence↗
PubMed1994

Radioimmunolocalization of human brain tumor: fundamental studies with indium-111 labeled monoclonal antibody G-22.

Monoclonal antibody (MCA) G-22 reacts selectively with human glioblastoma. Whole immunoglobulin G (IgG) and the F(ab')2 fragment of G-22 were labeled with indium-111, and injected into athymic nude mice bearing xenografts of a human glioblastoma cell line (U-251-MG). Radiolabeled G-22 retained its antigen-binding activity allowing clear visualization of transplanted tumors. Although the 111In-labeled F(ab')2 fragment had a higher tumor-to-tissue ratio than whole IgG, tumor concentration of 111In-labeled G-22 MCA was higher in the latter and it provided much better images for a longer time when visualized by gamma-scintigraphy. These results suggest that 111In-labeled G-22 may be a useful agent for brain tumor imaging.

Animals↗
PubMed1994

Plasmenylethanolamine in human intestinal mucosa detected by an improved method for analysis of phospholipid.

Analysis of phospholipid and their fatty acid composition of human intestinal mucosa was performed by an method elaborated to analyze the limited amount of sample with 2-dimensional TLC followed by lipid-phosphorus determination. Using this method, plasmenylethanolamine was detected in human intestinal mucosa and accounted for about 7% of phospholipid in small and large intestinal mucosa. The amounts of polyunsaturated fatty acids of phosphatidylethanolamine were higher than those of other phosphoglycerides in intestinal mucosa, hence, inflammation-related eicosanoids may originate from ethanolamine containing phospholipid.

Arachidonic Acid↗
PubMed1993

APC gene messenger RNA: novel isoforms that lack exon 7.

The APC gene at human chromosome 5q21 is responsible for familial adenomatous polyposis coli. Furthermore, sporadic cancers of not only colon but also other digestive organs often contain mutations in the APC gene. A dominant mouse mutation Min that was generated by chemical mutagenesis and causes polyposis in the digestive tract is in the mouse homologue of the human APC gene. The APC mRNA is generated from 15 exons. Two mRNA isoforms were reported which are produced by alternative splicing in the 9th exon. Here, we report novel mRNA isoforms that lack the 7th exon in both mouse and human cells.

Animals↗
PubMed1993

Expression cloning of a novel Gal beta (1-3/1-4) GlcNAc alpha 2,3-sialyltransferase using lectin resistance selection.

This report describes the isolation of a cDNA encoding a novel human Gal beta (1-3/1-4)GlcNac alpha 2,3-sialyl-transferase involved in the biosynthesis of the sialyl Lewis x determinant (NeuAc alpha 2-3 Gal beta 1-4(Fuc alpha 1-3)GlcNAc). A cDNA library of the human melanoma cell line WM266-4 was constructed in an Epstein-Barr virus-based cloning vector. Selection of the B-cell line Namalwa expressing transfected cDNAs in the presence of the cytotoxic lectin Ricinus communis agglutinin 120 gave a cDNA encoding a protein with type II transmembrane topology, as found for mammalian glycosyltransferases. The use of this lectin, which is specific to galactose residues (especially the Gal beta 1-4GlcNAc structure), originates from our prediction that the modification of the Gal beta 1-4GlcNAc structure (a backbone of the sialyl Lewis x structure) by glycosyltransferases may increase the levels of resistance to this lectin. Comparison of this cDNA sequence with those of three other cloned sialyltransferases revealed two conserved regions shared by all four enzymes. Expression of the COOH-terminal catalytic domain of this protein showed alpha 2,3-sialyltransferase activity with substrate specificity different from that of CMP-N-acetylneuraminate:N-acetyllactosaminide alpha-2,3-sialyltransferase (Gal-beta 1-3(4)GlcNAc alpha 2,3-sialyltransferase, EC 2.4.99.6). Furthermore, expression of this cDNA in Namalwa cells increased the level of sialyl Lewis x antigens. The cloning approach based on lectin resistance may be useful for the isolation of cDNAs encoding other mammalian glycosyltransferases.

Amino Acid Sequence↗