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Biomedical subjects

M Isobe

Publications and source records attributed to M Isobe.

At least 253 records · Page 14Linked to original sources
PubMed1992

Inhibitory effect of okadaic acid derivatives on protein phosphatases. A study on structure-affinity relationship.

The effect of structural modifications of okadaic acid (OA), a polyether C38 fatty acid, was studied on its inhibitory activity toward type 1 and type 2A protein phosphatases (PP1 and PP2A) by using OA derivatives obtained either by isolation from natural sources or by chemical processes. The dissociation constant (Ki) for the interaction of OA with PP2A was estimated to be 30 (26-33) nM [median (95% confidence limits)]. The OA derivatives used and their affinity for PP2A, expressed as Ki (in brackets) were as follows: 35-methyl-OA (DTX1) [19 (12-25) pM], OA-9,10-episulphide (acanthifolicin) [47 (25-60) pM], 7-deoxy-OA [69 (31-138) pM], 14,15-dihydro-OA [315 (275-360) pM], 2-deoxy-OA [899 (763-1044) pM], 7-O-palmitoyl-OA [greater than 100 nM], 7-O-palmitoyl-DTX1 [greater than 100 nM], methyl okadate [much greater than 100 nM], 2-oxo-decarboxy-OA [much greater than 100 nM] and the C-15-C-38 fragment of OA [much greater than 100 nM]. The sequence of the affinity of these derivatives for PP1 was essentially the same as that observed with PP2A, although the absolute values of Ki were very different for the enzymes. The inhibitory effect of OA on PP2A was reversed by applying a murine monoclonal antibody against OA, which recognizes modifications of the 7-hydroxyl group of the OA molecule. It has been shown by n.m.r. spectroscopy and X-ray analysis that one end (C-1-C-24) of the OA molecule assumes a circular conformation. The present results suggest the importance of the conformation for the inhibitory action of OA on the protein phosphatases. The ratios of the Ki values for PP1 to that for PP2A, which were within the range 10(3)-10(4), tended to be smaller for the derivatives with lower affinity, indicating that the structural changes in OA impaired the affinity for PP2A more strongly than that for PP1.

Antibodies, Monoclonal↗
PubMed1992

Specific acceptance of cardiac allograft after treatment with antibodies to ICAM-1 and LFA-1.

An indefinite survival of cardiac allografts between fully incompatible mice strains was observed when monoclonal antibodies (MAbs) to intercellular adhesion molecule-1 (ICAM-1) and leukocyte function-associated antigen-1 (LFA-1) were simultaneously administered after the transplantation for 6 days. Mice with long-term surviving cardiac allografts accepted skin grafts from the donor-strain but rejected skin grafts from a third-party strain. Because MAbs to ICAM-1 or LFA-1 alone were insufficient for prolonged tolerance, the two MAbs probably acted synergistically to induce specific unresponsiveness. Thus, ICAM-1----LFA-1 adhesion participates in the induction of allograft rejection and MAbs may be useful as therapeutic agents.

Animals↗
PubMed1992

Cross-reactivity of highly purified okadaic acid (OA), synthetic, spiroketal East sphere of OA and ciguatoxin.

This study presents data from the cross-reactivity analysis of purified ciguatoxin (CTX), okadaic acid (OA), and the East sphere or Fragment B-C of OA with their homologous antibodies, monoclonal antibodies to ciguatoxin (MAb-CTX) and okadaic acid (MAb-OA). The test system used was the stick enzyme immunoassay. MAb-CTX gave peak titers of 1.5ng, 10ng and 50ng respectively for CTX, East sphere and OA. Competitive inhibition analysis showed that 4ng purified CTX blocked completely MAb-CTX reaction with crude CTX, OA and East sphere of OA blocked at similar concentrations (approximately 50ng). The activity with MAb-OA in the homologous system with OA and East sphere was insignificant. This may be attributable to the improper concentrations used. The cross-reactivity between MAb-CTX with OA and its Fragment B-C may cause difficulty in the test system in its application to assess toxic fish due to ciguatoxin.

Animals↗
PubMed1992

Localization of the gene encoding the alpha subunit of human interleukin-5 receptor (IL5RA) to chromosome region 3p24-3p26.

The chromosomal location of the human gene for the alpha subunit of interleukin-5 receptor (IL5RA) has been determined. The human IL5RA gene was localized to the short arm of chromosome 3 by Southern blot analysis of DNA from a panel of mouse-human hybrid somatic cell lines. The IL5RA gene has been further localized to human chromosome region 3p24-3p26 by in situ hybridization of a molecularly cloned IL5RA cDNA fragment to metaphase chromosomes. The results suggest that the IL5RA locus is unlinked to other members of the hematopoietic receptor family. Assignment of the IL5RA gene to chromosome 3 at bands p26-p24 raises the possibility that it may be altered by certain nonrandom chromosomal abnormalities arising in human hematopoietic malignancies and solid tumors.

Animals↗
PubMed1992

Involvement of growth-associated protein-43 with irreversible neurite outgrowth by dibutyryl cyclic AMP and phorbol ester in NG108-15 cells.

Simultaneous treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) and dibutyryl cyclic AMP (diBu-cAMP) for 72 h induced neurites in NG108-15 cells significantly longer than treatment with each alone. Treatment for 72 h with both drugs induced irreversible neurite extension and a decline in protein kinase C activity, although neurites extended by diBu-cAMP alone disappeared after the withdrawal of the drug. The expression of growth-associated protein-43 (GAP-43) mRNA was also observed by a combined application of TPA and diBu-cAMP. The increased level of GAP-43 mRNA induced by treatment with both drugs for 72 h was maintained at least 24 h after withdrawal of the drugs. In cells transfected with GAP-43 cDNA, neurites induced by treatment with diBu-cAMP alone for 72 h were maintained at least 48 h after removal of the drugs. These results suggest that GAP-43 could be involved in the maintenance of elongated neurites and that a decline in protein kinase C activity may be involved in the accumulation of GAP-43.

Animals↗
PubMed1992

Imaging the rejecting heart. In vivo detection of major histocompatibility complex class II antigen induction.

BACKGROUND: Mice with abdominal heterotopic heart transplants were studied to determine whether scintigraphic detection of an increase in major histocompatibility complex (MHC) class II antigen expression could be used as a noninvasive method for diagnosing early rejection. METHODS AND RESULTS: Allografts from C3H/He (H2k) donors were transplanted into BALB/c (H2d) recipients (n = 18). Two of the 18 allografted mice were treated with cyclosporine (15 mg/kg/day), and two isografted mice served as controls. Each mouse was injected intravenously with 100 microCi of 111In-labeled anti-MHC class II monoclonal antibodies (10-2-16 and 14-4-4S) 24 hours before scintigraphy. After imaging, the mice were killed for tissue counting and histopathology. Radiotracer uptake in the grafts reflected the severity of rejection as determined by histopathological criteria. The percent injected dose per gram of tissue in excised grafts was 4.8 +/- 1.8 (mean +/- SD) for normal grafts (n = 8), 11.1 +/- 9.7 for grafts with grade IA rejection (n = 3, NS), 18.0 +/- 3.8 for grafts with grade IIIA rejection (n = 4, p less than 0.001 versus normal), 18.7 +/- 3.2 for grafts with grade IIIB rejection (n = 3, p less than 0.001 versus normal), and 22.6 +/- 5.4 for grafts with severe rejection (grade IV) (n = 3, p less than 0.001 versus normal). Rejecting allografts with lymphocyte infiltration but without significant myocyte necrosis could be identified by this scintigraphic method. In the BALB/c donor-C57BL/6 (H2b, IE-) recipient combination, rejecting allografts were visualized by 14-4-4S (anti-IEk,d,p,r) antibody but not by 10-2-16 (anti-IAk,r,s,f) antibody. This difference shows that class II antigens induced on donor hearts are solely responsible for the antibody uptake in positive scintigrams of rejecting allografts. CONCLUSIONS: We conclude that 111In-labeled anti-MHC class II antigen antibody imaging is a sensitive and noninvasive method for detecting cardiac allograft rejection.

Animals↗
PubMed1992

Purification and characterization of hamster hepatic microsomal N,O-acetyltransferase.

A microsomal N,O-acetyltransferase which activates carcinogenic arylacetohydroxamic acids was purified 75-fold from hamster liver sequentially by anion exchange column chromatography, chromatofocusing, gel filtration, and hydroxyapatite column chromatography. The purified enzyme, AT-2, was a glycoprotein with a molecular weight of 60000 and a pI value of 5.4. The N-terminal amino acid sequence of AT-2 was: 60000 and a pI value of 5.4. The N-terminal amino acid sequence of AT-2 was: Asp-Ser-Pro-Ser-Pro-Ile-Arg-Asn-Thr-His-Thr-Gly-Gln-Val-Arg-Gly-Leu-Val- His- Lys-. This sequence was highly homologous to that of the form 2 carboxylesterase of rabbit liver, but not to that of major hepatic microsomal carboxylesterases of hamster and other species. AT-2 catalyzed the hydrolysis of 4-nitrophenyl acetate and the N,O-acetyltransfer of N-hydroxy-2-acetylaminofluorene. Both enzyme activities were strongly inhibited by paraoxon, but not by iodoacetamide. These results demonstrate that this N,O-acetyltransferase is a member of carboxylesterase (EC 3.1.1.1).

Acetyltransferases↗
PubMed1992

[Liposarcoma of the transverse mesocolon--a case report].

Primary mesenteric liposarcoma is a rare neoplasm. We experienced a case of liposarcoma of transverse mesocolon. In our case, the examination of ultrasonography and CT scan revealed the tumor was solid and encapsulated. Preoperatively we suspected the tumor was malignant by the angiographic findings. Laparotomy revealed that the tumor was located in the transverse mesocolon and it could be removed easily. The histopathological diagnosis was myxoid type liposarcoma. It is said generally that liposarcoma is liable to recur after simple resection, therefore, we reconsider that we should have excised more extensively for this case. The patient is doing well without evidence of recurrence for 17 months after operation.

Aged↗
PubMed1992

[Cerebral blood flow reactivity to hyperventilation in children with spontaneous occlusion of the circle of willis (moyamoya disease)].

To elucidate the relationship between cerebral blood flow (CBF) after hyperventilation (HV) and the rebuild-up phenomenon on the encephaloelectrogram (EEG) in children with moyamoya disease, comparative study of CBF immediately after HV and CBF after administration of acetazolamide (Diamox) was examined. CBF was measured by means of single photon emission CT (SPECT) using the 133Xe inhalation method. The subjects were 11 children (21 hemispheres) with moyamoya disease who were divided into two groups as follows, 1) Bypass group; who underwent STA-MCA anastomosis with other synangiosis. 2) Non-Bypass group; who underwent only some synangiosis such as EDAS, EMAS, EMS. The summary of the results is shown below. Regional CBF (rCBF) after HV of the frontal lobes in the Non-Bypass group had an evident tendency to show low perfusion compared with CBF in other regions. The correlation between low perfusion area after HV, and areas where the increase of rCBF is less after administration of acetazolamide became clear. The strongest relation was observed between low perfusion after HV and re-build-up phenomenon on EEG. On the other hand, rCBF after HV of the frontal lobes in the Bypass group had, compared with other regions, no tendency to show low perfusion. From this study and our previous reports, it is assumed that there is some hemodynamic insufficiency in the frontal lobes of the Non-Bypass group. The reason why the reduction of rCBF was less after HV especially in the frontal lobes of the Bypass group is still unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1991

Establishment of a new Epstein-Barr virus nuclear antigen-positive B-cell line, BALL-2, with t(8;14) (q24;q32) chromosome abnormality from B-cell acute lymphoblastic leukemia, L2.

A new Epstein-Barr virus nuclear antigen (EBNA)-positive B-cell line, designated BALL-2, was spontaneously established from the peripheral blood of a 14-year-old boy with an EBNA-negative B-cell acute lymphoblastic leukemia (B-ALL), L2 in the French-American-British classification. The BALL-2 cell line grew in suspension with or without forming clumps of cells. The cultured cells exhibited lymphoid morphology with indented or lobulated nuclei, prominent nucleoli, and relatively abundant cytoplasm. Immunologic and cytogenetic studies showed that the BALL-2 cell line expressed the B-cell phenotype, CpIg+, SmIg+, CD19+, CD20+, CD38-, Ia+, and had chromosome translocation, t(8;14) (q24;q32). The same phenotypic and chromosome markers were present in original leukemia cells. These results indicated that the cell line was derived from the patient's leukemia cells. Unexpectedly, however, BALL-2 cells were positive for EBNA and EB virus DNA. Gene analysis of the BALL-2 cell line showed biallelic rearrangements in the JH locus. One of the JH rearrangement comigrated with a rearranged c-myc gene, indicating the translocation had occurred between JH and c-myc loci. The t(8;14) abnormality is a known chromosome marker of Burkitt lymphoma and L3 type ALL. Our studies revealed that this translocation and myc gene rearrangement can also be found in L2 type B-ALL.

Adolescent↗
PubMed1991

Relationship between chromosomal breakpoint and molecular rearrangement of T-cell antigen receptors in adult T-cell leukaemia.

The relationship between chromosome breakpoints associated with T-cell antigen receptor (TCR) genes and TCR-alpha/beta/tau/delta rearrangements of peripheral leukaemic cells in 8 Japanese patients with the acute type of adult T-cell leukaemia (ATL) was examined. Break of the 14q11 region with the assigned locus of TCR-alpha/delta was revealed in 6 patients, interstitial deletion of the 7q32-36 region with assigned locus of TCR-beta in 1 patient, and break of the 7p15 region with assigned locus of TCR-tau in 2 patients. Molecular analysis revealed TCR-alpha rearrangement in 7 patients, TCR-beta rearrangement in all patients, and TCR-tau rearrangement in 5 patients. TCR-delta was deleted in all patients. These findings indicate a close relationship between 14q11 anomaly and TCR-alpha rearrangement, which may play an important role in the leukaemogenesis of ATL.

Aged↗
PubMed1991

Early detection of rejection and assessment of cyclosporine therapy by 111In antimyosin imaging in mouse heart allografts.

BACKGROUND. Mice (n = 58) with abdominal heterotopic heart transplants were studied to examine the effectiveness of 111In-labeled antimyosin scintigraphy in the detection of rejection and to determine the consequence of cyclosporine therapy on the results. METHODS AND RESULTS. Allografts from B10D2 donors were transplanted into B6AF1 recipients. Of the 49 allografted mice, 19 were treated with cyclosporine (15 mg/kg.day). Nine isografted mice served as controls. Scintigraphy was performed by injecting 100 muCi 111In antimyosin monoclonal antibody 2-15 days after transplantation. An increase in the ratio of percent dose of antimyosin injected per gram (% dose/g) of the grafted heart (G) to that of the autologous heart (A) (G/A) as well as the increasing percent dose per gram of antimyosin in the grafts reflected the severity of histopathological rejection regardless of the presence or absence of cyclosporine. Scintigraphic images demonstrated unequivocally intense accumulation of 111In in rejected allografts as confirmed by histologically demonstrable myocyte necrosis. The G/A ratio in allografted mice with mildly deteriorated mechanical activity (4.2 +/- 1.0, mean +/- SD) was greater than that in mice with normal contractility (1.8 +/- 0.7) (p less than 0.001), and the necrosis correlated with this modest decline in mechanical function could be scintigraphically identified. Of mice with normally contracting allografts, the G/A ratio was greater in animals with demonstrated myocyte necrosis (2.6 +/- 0.5) than in those without necrosis (1.5 +/- 0.5) (p less than 0.001). In contrast, isografted mice or a subset of allografted mice treated with cyclosporine and not showing evidence of rejection did not manifest any significant change in G/A ratio, nor did they have scintigrams positive for rejection as late as 15 days after transplantation. CONCLUSIONS. These findings suggest that antimyosin scintigraphy is a sensitive and early indicator of cardiac transplant rejection and that it could be useful as a noninvasive method for assessing the efficacy of cyclosporine treatment.

Abdomen↗
PubMed1991

Cadmium injury of cultured human vascular endothelial cells.

The effect of cadmium chloride (CdCl2) on cultured human vascular endothelial (HVE) cells and cultured human fibroblasts (HAIN-55 cells) was investigated. Umbilical vein-derived HVE cells were collected by enzymatic digestion with collagenase. At the concentration of 0-10 microM, Cd had hardly any effect on the cell viability of either cells. The viability of HVE cells decreased markedly at 100 microM, but not that of HAIN-55 cells. Morphologic examination by phase contrast microscopy revealed a more damaging effect of Cd on HVE cells than on HAIN-55 cells. These results suggest that Cd is more cytotoxic to HVE cells than HAIN-55 cells.

Cadmium↗
PubMed1990

Rearrangements in the human T-cell-receptor alpha-chain locus in patients with adult T-cell leukemia carrying translocations involving chromosome 14q11.

We describe 5 cases of adult T-cell leukemia (ATL) carrying translocations at chromosome 14q11, where the genes for alpha- and delta-chains of the T-cell receptor (TCR alpha/delta) reside (Croce et al., 1985; Isobe et al., 1988). Since the TCR alpha/delta locus is the region where several types of chromosome translocations occur in T-cell tumors, rearrangements of the TCR alpha/delta locus in those ATL cases were studied as a first step to characterize these translocations at the molecular level. For this purpose we have generated an extensive series of probes to define the specificity and the diversity of rearrangement occurring at the widely spanned J alpha-C alpha locus and the complex D delta-J delta-C delta-V delta 2 locus. Using a set of probes, we have found the deletion of the TCR delta locus in all ATL cases, and at least 2 rearrangements in the J delta locus in each case of ATL. It is possible that translocations in the TCR alpha locus may be involved in ATL.

Chromosome Mapping↗
PubMed1990

Metabolic activation of the potent mutagen, 2-naphthohydroxamic acid, in Salmonella typhimurium TA98.

The objective of the present study was to explore the mechanisms responsible for the strong, direct-acting mutagenicity of 2-naphthohydroxamic acid (NHA) for Salmonella typhimurium TA98. NHA was converted to its O-acetate (O-Ac-NHA) by acetyl-CoA, in the presence of competent or heat-treated cell-free bacterial preparations. O-Ac-NHA, which is more mutagenic than NHA, reacted nonenzymatically with tRNA in neutral solutions with retention of both the naphthyl and carbonyl groups in the products, but NHA did not react. Enzymatic sulfate conjugation was not demonstrated. TA98 cells converted NHA to 2-aminoaphthalene, presumably through a Lossen rearrangement following O-acetylation or conjugation by other metabolic pathways. TA98 cells reduced O-Ac-NHA to 2-naphthamide, and NADH and NADPH were shown to be cofactors for reduction in the presence of a cell-free bacterial preparation. Although horseradish peroxidase and H2O2 catalyzed the binding of these compounds to tRNA, no evidence of oxidation of NHA or O-Ac-NHA was obtained with H2O2 and cell-free preparations of TA98 or the cells themselves, as judged by the lack of formation of the peroxidative product, 2-naphthoic acid. Both NHA and O-Ac-NHA reacted with DNA of TA98 with retention of both naphthyl group and carbonyl of the naphthoyl moiety in the adduct(s). These results suggest that NHA may be activated in TA98 by esterification, and the resulting metabolites may amidate or carbamoylate nucleic acids.

Biotransformation↗
PubMed1990

[The pharmacokinetics of pranoprofen in humans].

The pharmacokinetics of pranoprofen, 2-(5H-[1]benzopyrano[2,3-b]pyridin-7-yl) propionic acid (I) in humans were examined. 1-O-Acylglucuronide of I (II) and its isomer (III) were isolated from the human urine after oral administration of I. The stability of II was tested in order to establish the suitable conditions for the storage and handling of biological samples. Maximum stability of II was found at pH 3-4. Unchanged drugs, II and III were detected in the human plasma after oral administration of I. Plasma concentrations of these compounds reached the maximum at 1-2 h after the administration and thereafter decreased biphasically. From the urinary sample, 1-O-acylglucoside of I (IV) was detected in addition to unchanged drugs, II and III. Within 24 h after dosing, 1.3, 84.0, 7.0 and 0.6% of the dose were excreted as I, II, III and IV, respectively and the total urinary excretion amounted to 92.9% in term of unchanged drug.

Administration, Oral↗
PubMed1990

In vitro toxicity test of poisonous mushroom extracts with isolated rat hepatocytes.

Effects of poisonous mushroom extracts on isolated rat hepatocytes were studied. Though no significant decrease in the cell viability was observed during the incubation of hepatocytes with the extracts at a concentration of 5% (v/v) of Amanita abrupta, A. gymnopus, and A. virosa caused marked decreases in the intracellular glutathione content in sharp contrast to the extracts of A. volvata and A. flavipes. Comparative toxicity tests were carried out for the effects of the extract of A. abrupta, dl-propargylglycine, and alpha-amanitin. The extract of A. abrupta at a concentration of 1% (v/v) caused a marked decrease in the glycogen content, a noticeable elevation in the phosphorylase alpha activity, and a slight acceleration of lipid peroxidation in the hepatocytes. Although dl-propargylglycine decreased the intracellular glutathione content progressively with the incubation time, a significant effect of the chemical on lipid peroxidation and the glycogen content was observed only after prolonged incubation at a concentration of 5 mM. On the other hand, alpha-amanitin exerted a little effect on the hepatocytes at 1 microM. These results have indicated that the intoxication by the extract of A. abrupta on the hepatocytes might not due to independently each component, dl-propargylglycine and alpha-amanitin, but combined effect of these components or unidentified substances.

Alkynes↗