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Biomedical subjects

M Isobe

Publications and source records attributed to M Isobe.

At least 217 records · Page 12Linked to original sources
PubMed1995

Cerebral haemodynamics and long-term prognosis after extracranial-intracranial bypass surgery.

The effectiveness of extracranial-intracranial arterial (EC-IC) bypass surgery for haemodynamic stroke remains controversial. In this study correlation of presurgical and postsurgical cerebral haemodynamics with long term prognosis was evaluated. Twenty eight patients (25 men, three women: mean age 61.4 (SD 8.2) years) with reduced cerebrovascular reserve due to steno-occlusive cerebral vascular disease formed the study group. Measurement of mean hemispheric cerebral blood flow (mCBF) and the cerebral vasodilatory capacity (% mCVR) with an intravenous acetazolamide injection were performed by a xenon-133 inhalation method and SPECT. Patients were treated with EC-IC bypass surgery and measurements of mCBF and % mCVR were made again about one month after surgery. The patients were then observed for a long period (range 27-115 months). During the observation period, four patients experienced subsequent ischaemic strokes. The presurgical and the postsurgical resting mCBF for the affected hemisphere were significantly reduced in the patients with strokes during follow up compared with the values in patients without strokes during follow up (P < 0.03 and 0.01 respectively). The % mCVR of the affected hemisphere was significantly raised after surgery in all patients except one (P < 0.01). The postsurgical change in resting mCBF was not unidirectional. In conclusion, resting mCBF was unchanged and % mCVR was improved after EC-IC bypass surgery in patients with reduced cerebrovascular reserve. The group of patients with a reduced presurgical and postsurgical resting mCBF continue to be a high risk group for subsequent ischaemic stroke seen after EC-IC bypass surgery.

Aged↗
PubMed1995

Depletion of glutathione and hepato-toxicity caused by vinyl ethers in mice.

4-Nitrophenyl vinyl ether (NPVE) and phenyl vinyl ether (PVE) administered i.p. in mice lowered hepatic non-protein sulfhydryl (NP-SH) content, but did not elevate the serum glutamate pyruvate transaminase (GPT) activity. n-Butyl vinyl ether (BVE) showed no significant effects either on the NP-SH content or on the serum GP activity. Mice pretreated with buthionine sulfoximine were sensitive to the potential toxicity of NPVE. These results showed that aryl vinyl ethers, NPVE and PVE, are more toxic than the alkyl vinyl ether, BVE, and that glutathione plays an important role on the protection of hepatic injury by reactive metabolite(s) derived from vinyl ethers.

Alanine Transaminase↗
PubMed1995

[Characteristics and osteoinductive activity of bone morphogenetic protein (BMP) encapsulated with poly (DL-lactide-co-glycolide)].

To develop a controlled release system for bone morphogenetic protein (BMP), encapsulation of BMP with poly (DL-lactide-co-glycolide) (PLGA)/poly (ethyleneglycol) (PEG) mixture was accomplished by an emulsion interfacial precipitation method. The surface morphology, average particle size and hydrolytic degradation rate of two types (PLGA and PLGA/PEG) of capsules were examined. The encapsulation yield and release rate of BMP in vitro were measured using fluorescein isothiocyanate-labeled BMP. The amount of BMP released from the PLGA and PLGA/PEG capsules increased between day 3 and day 5. The PLGA capsules released much BMP in this period compared to the PLGA/PEG capsules. These capsules containing BMP were implanted in subcutaneous areas of rats to examine the osteoinductive activity in vivo. They were digested completely, however, only the PLGA capsules containing BMP could induce new bone formation, including bone marrow, three weeks after implantation. From these results, it was considered that the PLGA capsules containing BMP are a prominent system to induce bone in clinics.

Animals↗
PubMed1994

Identification of the TCL1 gene involved in T-cell malignancies.

The TCL1 locus on chromosome 14q32.1 is frequently involved in chromosomal translocations and inversions with one of the T-cell receptor loci in human T-cell leukemias and lymphomas. The chromosome 14 region translocated or rearranged involves approximately 350 kb of DNA at chromosome band 14q32.1. Within this region we have identified a gene coding for a 1.3-kb transcript, expressed only in restricted subsets of cells within the lymphoid lineage and expressed at high levels in leukemic cells carrying a t(14;14)(q11;q32) chromosome translocation or a inv(14)(q11;q32) chromosome inversion. The cognate cDNA sequence reveals an open reading frame of 342 nt encoding a protein of 14 kDa. The TCL1 gene sequence, which, to our knowledge, shows no sequence homology with other human genes, is preferentially expressed early in T- and B-lymphocyte differentiation.

Amino Acid Sequence↗
PubMed1994

Immunosuppression to cardiac allografts and soluble antigens by anti-vascular cellular adhesion molecule-1 and anti-very late antigen-4 monoclonal antibodies.

Effective activation of T cells in immune responses depends on two signals, one from the CD3/TCR complex and another from accessory cell surface proteins. Very late Ag-4 (VLA-4) can exert a costimulatory function upon binding with vascular cellular adhesion molecule-1 (VCAM-1). We investigated the effects of mAbs against VCAM-1 and VLA-4 on cardiac allograft survival and humoral response to soluble Ags. BALB/c hearts were transplanted into C3H/He recipients. mAbs (100 micrograms/day) were administered i.p. for the first 6 days. Graft survival in mice treated with M/K-2 (anti-VCAM-1; median survival: 20 days, n = 6) and those treated with PS/2 (anti-VLA-4; 30 days, n = 6) was greater than that in control mice (8 days, n = 7). Eight of 18 mice treated with both M/K-2 and PS/2 accepted the grafts over 65 days, and five of them accepted the grafts over 100 days. Allografts treated with the two mAbs showed scattered infiltration of leukocytes without evidence of active rejection at 65 days. Mice with long-surviving cardiac grafts were challenged with skin grafts from donor and third-party (C57BL/6) strains. Survival of the donor-type skin was significantly greater than that of the third-party skin. One mouse specifically accepted the donor-type skin indefinitely (> 150 days). FACS analysis of splenocytes at 55 days after transplantation showed complete recovery of VLA-4 expression from a down-regulation observed at day 7. In addition, mice immunized with heat-aggregated human gamma-globulin did not produce specific Ab, even after boost immunization, if PS/2 was administered at the time of the first immunization. This unresponsiveness to xenogeneic protein lasted for more than 50 days. These results indicate that in vivo administration of anti-VCAM-1 and anti-VLA-4 mAbs induces specific immunosuppression to cardiac allografts and soluble Ags.

Animals↗
PubMed1994

Assignment of the true and processed genes for human glycine decarboxylase to 9p23-24 and 4q12.

Southern analysis using a human glycine decarboxylase cDNA probe and genomic DNA preparations from Chinese hamster-human hybridoma cell lines demonstrated that on the segregated human chromosomes, 4 and 9, there are glycine decarboxylase cDNA-related sequences. The finding is confirmatory of the fact that fragments of both the true and processed genes for this protein have been cloned. Since one of four HindIII fragments revealed in the present Southern analysis matched requirements for the property expected from the restriction map reported for the processed gene, this was located on chromosome 4. The three remaining signals were consequently ascribed to fragments from the true gene on chromosome 9. Fluorescence in situ hybridization using the genomic clones assigned the true and processed genes to 9p23-24 and 4q12, respectively.

Amino Acid Oxidoreductases↗
PubMed1994

Molecular characterization of ovary trehalase of the silkworm, Bombyx mori and its transcriptional activation by diapause hormone.

We have isolated a cDNA encoding ovary trehalase of the silkworm, Bombyx mori. Sequence analyses revealed that the isolated cDNA contains 3143 nucleotides and comprises 579 amino acids, including a cleavable signal sequence and five potential N-glycosylation sites. Northern blot analysis showed a 3.0 kb transcript in developing ovaries carrying membrane-bound trehalase. A single copy of trehalase gene was present in the haploid genome of the silkworm. The effect of diapause hormone on the accumulation of trehalase mRNA was examined on developing ovaries in in vivo and in vitro conditions. The synthetic diapause hormone brought about a 6-fold increase in trehalase mRNA content in ovaries 4 h after injection. The similar increase was found in ovaries which were incubated in vitro with diapause hormone. Coincubation of ovaries with diapause hormone and actinomycin D could not increase the mRNA level in ovaries, and maintained a basal level which was found in ovaries incubated without diapause hormone. These results indicate that diapause hormone stimulates transcription of the trehalase gene in developing ovaries of the silkworm.

Amino Acid Sequence↗
PubMed1994

A novel dodecadepsipeptide, cereulide, isolated from Bacillus cereus causes vacuole formation in HEp-2 cells.

A HEp-2 cell-vacuolation factor was extracted and purified from the culture supernatant of a Bacillus cereus strain which caused emetic-syndrome food poisoning. The final preparation was chemically pure, and the toxin was named as cereulide. Mass spectrometry, NMR studies and chemical degradation revealed that the cereulide is a cyclic dodecadepsipeptide, (D-O-Leu-D-Ala-L-O-Val-L-Val)3, which is closely related to the potassium ionophore, valinomycin.

Amino Acid Sequence↗
PubMed1994

Cloning and sequence analysis of a hamster liver cDNA encoding a novel putative carboxylesterase.

A full-length cDNA encoding for a putative carboxylesterase was isolated from a hamster liver cDNA library. The cDNA consisting of 1911 base pairs contained an open reading frame of 1683 base pairs encoding for a polypeptide of 561 amino-acid residues, including 27 N-terminal amino-acid residues for signal peptide. The deduced amino-acid sequence of the cDNA is in 67% homology with the amino-acid sequence of rabbit form 2 carboxylesterase, which has not yet been cloned. It also had many structural features highly conserved among carboxylesterase isozymes.

Amino Acid Sequence↗
PubMed1994

Scintigraphic detection of early cardiac rejection by iodine 123-labeled monoclonal antibody directed against monomorphic determinant of major histocompatibility complex class II antigens.

Although it has been shown that early cardiac rejection can be visualized by radioimmunoscintigraphy targeting major histocompatibility complex class II antigen, the use of antibodies that bind to a polymorphic determinant of class II antigen has certain disadvantages for clinical application. This investigation was designed to examine the feasibility of scintigraphic detection of cardiac allograft rejection by using a monoclonal antibody that reacts with a monomorphic determinant of rat IA antigens. Twenty PVG rats (RT1c) and five DA rats (RT1a) underwent heterotopic transplantation with DA hearts. Two of the 20 allografted rats were treated with FK506 (2 mg/kg/day). Seventeen rats were injected intravenously with 80 microCi of iodine 123-labeled monoclonal antibody reactive with a monomorphic determinant of rat major histocompatibility complex class II antigens (Ox6) 16 hours before scintigraphy, and images were compared with those obtained by injection of 123I-labeled monoclonal antibody against a polymorphic determinant of class II antigens (F17-23-6, anti-RT1a) (n = 8). Background activity was higher in rats injected with Ox6 than in rats injected with F17-23-6. Uptake of labeled Ox6 in the grafts reflected the severity of rejection as determined by histopathologic criteria. Rejecting allografts with lymphocyte infiltration but without myocyte necrosis could be identified by the scintigraphy with use of labeled Ox6.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The core and complementary sequence responsible for biological activity of the diapause hormone of the silkworm, Bombyx mori.

To evaluate the structure-function relationship of the diapause hormone of the silkworm, Bombyx mori, the entire molecule and selected fragment and deleted analogues were chemically synthesized to compare their biological activity. The C-terminal pentapeptide amide was the shortest fragment that elicited 11% diapause eggs at maximum, indicating that this sequence is the core-active structure required for a biological response. The full biological response of about 70% diapause eggs was expressed by the C-terminal hexapeptide amide. However, an ED50 value of this peptide amide was 1000-fold higher than that of the parent molecule. The serial elongation of peptide chain lengths toward the N-terminus brought about the sudden decrease in ED50 values at two positions between Arg9-Gly10 and Thr1-Asp2. The deletion of duplicated sequence(s) located in the middle part of the molecule or the truncation of N-terminal region of the parent molecule increased ED50 values but had no effects on response. Thus, N-terminal region and duplicated sequences act as the complementary structures for full potency of diapause hormone.

Amino Acid Sequence↗
PubMed1994

Silkworm diapause hormone, structure-activity relationships indispensable role of C-terminal amide.

To determine the structure-activity relationships of the silkworm diapause hormone, a series of peptide analogs having different chain lengths starting from the parent C-terminus and analogs having identical sequences with free acid C-termini were chemically synthesized by solid-phase Fmoc methodology and were further purified by HPLC. Bioassay showed that the analogs with free acid C-termini were non active. The retained activities of those shorter chains were shown only with the amidated C-terminal analogs among which the potency depended on the length of the chain. The active peptides required two minimal elements; namely the sequence near and the amidation of the C-terminus. There was no difference in enzymatic digestion of the C-terminally amidated or free acid analogs in pupal haemolymph. Hence the absence of DH activity of the free acid analogs was not because of being selectively hydrolyzed faster than the C-terminally amidated peptides. This suggested that existence of a certain higher order structure could be involved in expressing hormonal activity, or that the negative charge of the free acid terminus may be deleterious to a proper ligand receptor interaction. Since most of the hydrophobic amino acids were located near the C-terminal portion, both the hydrophobicity of the portion near and the amidation of the C-terminus were indispensable structures for diapause hormone activity.

Amides↗