Biomedical subjects

M Shibuya

Publications and source records attributed to M Shibuya.

At least 199 records · Page 11Linked to original sources

PubMed1996

Deletion of the ABL SH3 domain reactivates de-oligomerized BCR-ABL for growth factor independence.

Biological activities of BCR-ABL, an activated tyrosine kinase oncogene responsible for pathogenesis of human leukemias, can be completely inactivated by a deletion of the BCR aminoterminal sequence with tetramerizing property (BCR-ABL delta 1-40). We attempted several ways to restore the ability to induce growth factor independence to the de-oligomerized BCR-ABL delta 1-40 and found that an additional deletion of the ABL SH3 domain could. In BCR-ABL delta 1-40 reactivated by the SH3 deletion, transphosphoryation of other cellular proteins like p62 or SHC in vivo and autophosphorylation with recruitment of GRB-2 were also recovered.

Adaptor Proteins, Signal Transducing↗

PubMed1996

CD43 expression in a B cell lymphoma, WEHI 231, reduces susceptibility to G1 arrest and extends survival in culture upon serum depletion.

CD43 is a major surface sialoprotein on hemopoietic cells, whose extracellular domain is heavily O-glycosylated. The functional role of CD43 in the hemopoietic system is not fully understood; however, it has been suggested that CD43 may have a role in cell-cell repulsion and in modifying T cell proliferation and activation. CD43 is expressed in immature B cells in the bone marrow, but not by peripheral B cells, except for B-1 B cells and plasma cells. To analyze the biological effect of CD43 in B-lineage cells, we transfected mouse CD43 cDNA into a CD43- B cell lymphoma, WEHI 231, and the growth and survival in culture were compared to those of a parental cell line, human CD8 transfectants, and CD43- revertants established from CD43+ clones. We observed that CD43 expression supported cell growth in culture upon serum reduction, whereas growth of CD43- cell lines was barely detected under this condition. CD43- cell lines accumulated in G1 phase of the cell cycle, and the numbers of viable cells were greatly reduced during culture upon serum depletion, whereas expression of CD43 reduced the susceptibility to G1 arrest and temporarily retarded the apoptotic process, which, in turn, resulted in an increase and maintenance of the number of viable cells in culture. The results suggest that CD43 may have some role in the survival and expansion of B-lineage cells. The biological effect of CD43 was initiated without stimulation by cross-linking and was significantly impaired by replacement of the extracellular domain by the human CD8 extracellular domain. The basis of these regulatory processes is discussed.

Animals↗

PubMed1996

Increase of vascular endothelial growth factor mRNA expression by 1,25-dihydroxyvitamin D3 in human osteoblast-like cells.

Vascular endothelial growth factor (VEGF), a secreted endothelial cell-specific mitogen, is produced in endocrine organs and regulated by trophic hormones. Because angiogenesis and osteogenesis are closely regulated, we studied whether human osteoblast-like cells produce VEGF, and if so, what factors regulate VEGF mRNA expression. Human osteoblast-like cells (HObLC) derived from trabecular bone explants were cultured in alpha-MEM supplemented with 10% fetal calf serum. Northern blot analysis revealed that HObLC expressed VEGF mRNA, as did several human osteosarcoma cells. 1,25-(OH)2D3 increased the steady-state levels of VEGF mRNA in a time- and concentration-dependent manner in HObLC and one of the osteosarcoma cell lines, SaOS-2, accompanied by an increase in the concentration of immunoreactive VEGF in the conditioned medium. PTH and IGF-I also increased the level of VEGF mRNA in HObLC and SaOS-2 cells. Furthermore, 12-O-tetradecanoylphorbol ester stimulated VEGF mRNA in a time-and concentration-dependent manner. The VEGF mRNA expression induced by 1,25-(OH)2D3 was completely inhibited by H-7, but only partially by staurosporine. We have demonstrated that PTH, IGF-I, and most potently 1,25-(OH)2D3 stimulate the mRNA expression and secretion of VEGF in human osteoblast-like cells, suggesting that one of the anabolic effects of 1,25-(OH)2D3 on skeletal tissue may be mediated by VEGF produced by osteoblasts.

Autoradiography↗

PubMed1996

Changes in serum cytokine concentrations after neurosurgical procedures.

Cytokine responses to surgical trauma have been studied in 70 patients undergoing various neurosurgical procedures. Serum concentrations of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), interleukin-8, (IL-8), tumour necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) were measured before and after surgery using enzyme-linked immunosorbent assays. The serum concentrations of IL-1 beta, IL-8, TNF-alpha, and IFN-gamma did not change significantly following neurosurgical operations. In contrast, serum IL-6 levels were significantly elevated following surgery, peaking at postoperative day 1 and then gradually decreasing. Maximum IL-6 concentrations were considerably higher in patients who underwent surgery for brain tumours or aneurysms as compared with patients who had a ventriculoperitoneal shunt, neurovascular decompression or transsphenoidal adenomectomy. Intra-operative use of methylprednisolone, which is known to block the production and action of cytokines, suppressed the increase in IL-6 levels after surgery. There was a statistically significant correlation between the IL-6 peak concentration and the length of surgery in patients not treated with steroids, but not in patients treated with steroids. Additionally patients who underwent supratentorial surgery had higher peak concentrations of IL-6 than those who underwent infratentorial surgery. These results suggest that IL-6 is an early marker of tissue damage and may be useful in assessing the extent of postoperative stress.

Adolescent↗

PubMed1996

Vasodilation by intrathecal lipopolysaccharide of the cerebral arteries after subarachnoid haemorrhage in dogs.

To investigate the influence of inducible nitric oxide synthase on cerebral arteries after subarachnoid haemorrhage (SAH) in vivo, lipopolysaccharide (LPS), a major inducer of inducible nitric oxide synthase, was injected intracisternally into control and SAH model dogs. Intracisternal injection of LPS (0.5 mg) produced a long-lasting, submaximal vasodilation of the basilar artery of control dogs on angiography. This effect became significant at 4 hours after LPS injection and plateaued after 6 hours. This vasodilation was reduced by N(G)-monomethyl-L-arginine. Vasopressin slightly suppressed the vasodilation, while bradykinin increased it. The concentration of L-arginine in CSF decreased after LPS injection, while that of L-citrulline increased. In cytokines, the concentration of tumour necrosis factor-alpha; (TNF-alpha;) in CSF increased transiently at 4 hours after LPS injection, while interleukin-1 beta, interleukin-6, interferon-gamma, did not change. These data suggest that vasodilation by LPS is mainly due to nitric oxide predominantly synthesized by an inducible nitric oxide synthase, proximally induced by TNF-alpha. Our data make it unlikely that SAH itself induces the inducible nitric oxide synthase in vascular tissue, since isolated endothelium-denuded basilar artery from SAH model dogs did not respond to L-arginine. In SAH model dogs, the degree of vasodilation by LPS differed with the severity of vasospasm. Vasodilation was much greater in mild than in severe vasospasm in dogs, and was increased by superoxide dismutase. These findings suggest that the induction of inducible nitric oxide synthase or its activity may be less effective in severe vasospasm.

Analysis of Variance↗

PubMed1996

Motion and image artifacts of various intracranial aneurysm clips in a magnetic field.

Deflection angles of 36 types of Sugita intracranial aneurysm clips (Elgiloy), 2 types of Yasargil clips (Phynox), a Kirschner chip (SUS316) and a silver clip were examined by suspending each in a 1.5-tesla MRI (TOSHIBA MRT-200/FXII). Image artifacts of 5 types of intracranial aneurysm clips were also studied quantitatively with respect to their ratio of artifact/actual clip size using a spin-echo sequence with T1-weighted (Time of repetition (TR) = 500 ms, Time of echo (TE) = 20 ms) and T2-weighted (TR = 2000 ms, TE = 80 ms) images. All the Sugita clips from mini type to long type showed a deflection angle of less than 1.0 degree, the Yasargil clips less than 2.0 degrees, the Kirschner chip less than 6.0 degrees, and the silver chip did not move at all. Both brands of clips are therefore suitable for intracranial applications. The artifact size was directly proportional to the clip size and weight, though the ratio of artifact/actual width tended to decrease proportionately as the actual size and weight increased. The ratio of the width seemed slightly bigger than that of the length, but the difference did not reach statistical significance. There was no significant difference in the ratio of image artifacts/clip size between T1- and T2-weighted images.

Artifacts↗

PubMed1996

Rapid enlargement of a syringomyelia cavity following syringo-subarachnoid shunt: case report.

We describe a patient who presented with syringomyelia 20 years following an operation for foramen magnum meningioma. A syringo-subarachnoid shunt was placed, which connected the syrinx and the cerebello-pontine angle cistern. Following shunt placement, the patient's symptoms rapidly progressed, and magnetic resonance imaging (MRI) revealed enlargement of the syrinx. The symptoms improved with a decrease in syrinx size after placement of a syringo-peritoneal shunt in combination with revision of the syringo-subarachnoid shunt, changing the position of the subarachnoid tip to the caudal spinal subarachnoid space. The mechanism of rapid enlargement of the syrinx cavity following placement of the syringo-subarachnoid shunt is discussed.

Aged↗

PubMed1996

Extracerebral cavernous angiomas of the cavernous sinus in the middle fossa.

UNLABELLED: Intracranial extracerebral cavernous angiomas (ECCAs) share the same histologic features as intracerebral lesions, but their clinical picture is different. Surgical treatment of ECCAs of the cavernous sinus remains a challenge for the neurosurgeon because of a high mortality and morbidity due to uncontrollable and massive hemorrhage. METHODS: We have experienced seven patients with ECCAs of the cavernous sinus between 1982 and 1994. All cases were verified histologically during surgery and two were totally resected during the first surgical attempt. Six of seven patients were female. The mean age at diagnosis was 54.5 years (range; 43 to 71 years). RESULTS: Computed tomography showed a round or dumbbell-shaped mass in the area of the cavernous sinus. Magnetic resonance imaging revealed a low to isointense mass lesion on the T1-weighted image. Only one of our patients showed a minimal amount of vascular staining on angiography. The total excision of these malformations was difficult because intraoperative bleeding could be profuse. In one case, radiation therapy induced a reduction in the size of the tumor after failure of surgical removal. CONCLUSIONS: In planning surgical strategy for ECCAs, care should be taken to control the massive bleeding. Radiation therapy is helpful to suppress the tumor growth.

Adult↗

PubMed1996

Vibration-induced finger flexion reflex and inhibitory effect of acupuncture on this reflex in cervical spinal cord injury patients.

The vibration-induced finger flexion reflex (VFR) and the inhibitory effect of acupuncture on this reflex were studied in five cervical spinal cord injury patients (C-SCIs). VFR, which is a tonic finger flexion reflex induced by vibratory stimulation on the finger tip, was induced before and after acupuncture was carried out on the same hand. A stainless steel needle was inserted to the Hoku point. As in healthy subjects, VFR was performed and it was significantly inhibited by acupuncture in the C-SCIs; mean maximum VFR was 204.2 +/- S.E. 68.6 g before and 119.8 +/- S.E. 42.2 g after acupuncture. The present results suggest that at least part of the reflex center for VFR is located in the spinal cord and that part of VFR inhibition by acupuncture may be mediated via the spinal cord.

Acupuncture Therapy↗

PubMed1996

Monoclonal antibody against the fusion junction of a deletion-mutant epidermal growth factor receptor.

A mouse monoclonal antibody (IgG2b), 3C10, was produced against the truncated epidermal growth factor receptor (EGFR), encoded by the (type III) in-frame deletion mutation of 801 nucleotides of EGFR affecting the external domain, known to be expressed in some human glioblastoma. As this mutation newly generates a glycine residue at the fusion point, a 14 amino acid peptide around the fusion junction including this glycine was chemically synthesised and used for immunisation of (B6 x DBA/2) F1 mice. Flow cytometric analysis showed 3C10 antibody staining of a mouse NIH/3T3 transfectant (ERM5) with the type III EGFR deletion-mutant gene, but not one with wild-type EGFR. The antibody immunoprecipitated the truncated EGFR protein with a molecular mass of approximately 140 kDa from ERM5 cells. Immunostaining of glioblastomas revealed binding in the case with the type III EGFR mutation, the five other specimens without the mutation being negative despite overexpression of EGFR in some cases.

3T3 Cells↗

PubMed1996

Neuroprotective properties of a protein kinase inhibitor against ischaemia-induced neuronal damage in rats and gerbils.

1. The neuroprotective properties of fasudil (HA1077), a novel protein kinase inhibitor, were evaluated in two animal models of cerebral ischaemia: transient bilateral carotid artery occlusion in Mongolian gerbils and cerebral microembolization in rats. 2. The cytoprotective effect of fasudil on delayed neuronal death in gerbils was compared with the effects of nimodipine, a calcium channel antagonist and ozagrel, a thromboxane A2 synthetase inhibitor. The average of the neuronal cell density in the ischaemic control group was 17.8 +/- 2.1 cells mm-1, whereas fasudil (30 mg kg-1) significantly diminished the loss of CA1 neurones with the average of the neuronal cell density of 101.0 +/- 22.0 cells mm-1; nimodipine (10 mg kg-1) and ozagrel (30 mg kg-1) did not significantly protect against the ischaemia-induced neuronal loss. 3. In the rat model, the effects of fasudil on the histological and neurological consequences of cerebral microembolization produced via the injection of microspheres were examined. Twenty-four hours after the injection of microspheres into the internal carotid artery, all animals in the control group showed typical symptoms of stroke. Neurological function was significantly improved in the fasudil-treated animals. In the controls, the infarcted area in a cortical slice selected to include the hippocampal area was 0.25 +/- 0.01 cm2 (mean +/- s.e.mean) (43.9 +/- 2.4% of cortical section of the half hemisphere); the difference was significant compared to the mean area of 32.7 +/- 2.8 and 21.5 +/- 4.8% observed in rats treated with fasudil (3, 10 mg kg-1), respectively. Fasudil (10 mg kg-1) significantly suppressed the increased water content in ischaemic brain tissues (saline-treated rats, 82.4 +/- 0.2% vs fasudil-treated rats, 81.0 +/- 0.4%). 4. These results suggest that: (i) various protein kinases are involved in the pathogenesis of ischaemic injury; and (ii) the inhibition of protein kinases may be efficacious in preventing neuronal death, thus improving neurological function in the brain damage associated with ischaemic stroke.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1996

Simple evaluation method of biocompatibility of artificial oxygenator hollow fiber.

We made miniature modules filled with artificial oxygenator hollow fibers and conducted a simple experiment to study the effect of different membrane structures on the blood. Three types of modules were made: one filled with polyolefin, one filled with polypropylene, and a blank module. The 3 modules were connected through 3 fine tubings to one needle so that the same blood that passed through the 3 modules could be analyzed simultaneously. Nonheparinized blood was continuously withdrawn from 6 healthy volunteers using a small pump and passed through the circuit by a single pass (10 ml/min, for 10 min). Platelet count, thrombin-antithrombin complex, and complement-3 were measured in the blood collected at 10 min from the outlet of each module. The results showed significantly better biocompatibility of polyolefin than polypropylene, which is attributable to the dense layer of the blood contact surface of polyolefin fibers. This method is useful in assessing biocompatibility of various hollow fibers in a simple and safe manner.

Analysis of Variance↗

PubMed1996

DOCK180, a major CRK-binding protein, alters cell morphology upon translocation to the cell membrane.

CRK belongs to a family of adaptor proteins that consist mostly of SH2 and SH3 domains. Far Western blotting with CRK SH3 has demonstrated that it binds to 135- to 145-, 160-, and 180-kDa proteins. The 135- to 145-kDa protein is C3G, a CRK SH3-binding guanine nucleotide exchange protein. Here, we report on the molecular cloning of the 180-kDa protein, which is designated DOCK180 (180-kDa protein downstream of CRK). The isolated cDNA contains a 5,598-bp open reading frame encoding an 1,866-amino-acid protein. The deduced amino acid sequence did not reveal any significant homology to known proteins, except that an SH3 domain was identified at its amino terminus. To examine the function of DOCK180, a Ki-Ras farnesylation signal was fused to the carboxyl terminus of DOCK180, a strategy that has been employed successfully for activation of adaptor-binding proteins in vivo. Whereas wild-type DOCK180 accumulated diffusely in the cytoplasm and did not have any effect on cell morphology, farnesylated DOCK180 was localized on the cytoplasmic membrane and changed spindle 3T3 cells to flat, polygonal cells. These results suggest that DOCK180 is a new effector molecule which transduces signals from tyrosine kinases through the CRK adaptor protein.

3T3 Cells↗

PubMed1996

cDNA and genomic DNA clonings of chalcone synthase from Pueraria lobata.

Four cDNAs encoding chalcone synthase (CHS), the key enzyme in flavonoid biosynthesis, were isolated from Pueraria lobata cells challenged with yeast extract elicitor using bean CHS cDNA as a probe. The longest clone contained a complete open reading frame of 1170 bp which would predict a protein of about 43 kDa. The others were not full-length clones. Using isolated cDNA as a probe, Southern blot hybridization of genomic DNA fragments revealed the presence of multiple CHS genes in the P. lobata genome. We cloned and sequenced one CHS genomic clone, gCHS14, whose 5' untranslated region showed homology with the bean CHS gene CHS15 and included the several reported sequences characteristic of stress response.

Acyltransferases↗

PubMed1996

[Involvement of the VEGF-Flt-receptor family in angiogenesis].

Angiogenesis is important not only in normal embryogenesis, tissue organization and its maintenance but also in pathological processes such as ocular disease in diabetes mellitus and rapid growth of tumors in vivo. Recently, endothelial cell-specific growth factor (VEGF) and its receptors (Flt family) has been characterized, and this ligand-tyrosine kinase receptor is considered to be one of the most important systems involved in angiogenesis. VEGF is induced by a variety of normal or tumor cells under conditions such as hypoxia and hypoglycemia and in the presence of substances such as hormones and growth factors. On the other hand, receptors of the Flt family (Flt-1, KDR/Flk-1, Flt-4) are basically strictly expressed only on vascular endothelial cells with a rare exception. Thus, the stimulation of VEGF-Flt towards angiogenesis is through a paracrine mechanism. A direct involvement of Flt-1 and KDR/Flk-1 in vasculogenesis/angiogenesis has recently been demonstrated by gene targetting studies. Blocking of this system might be a useful tool for suppression of solid tumors in vivo.

Amino Acid Sequence↗

PubMed1996

Characterization of the promoter region for flt-1 tyrosine kinase gene, a receptor for vascular endothelial growth factor.

The flt-1 gene encodes a Vascular Endothelial Growth Factor receptor, (Flt-1), whose expression is restricted to vascular endothelial cells. To characterize the cell type specificity of flt-1 gene expression, we isolated the upstream genomic DNA of the human flt-1 gene and identified a single transcription initiation site 29 bp downstream of a TATA box. DNA sequencing revealed that one TATA box, four GC boxes, nine ETS motifs and one CRE motif were present in the upstream 489 bp region of exon 1. Functional analyses using CAT plasmids in 293E1 cells, which express significant levels of the flt-1 gene, showed that the -229 to +8 region is essential for the cell type-specific expression of this gene. Deletion mutant analysis also pointed to the possible existence of negative and positive regulatory elements in the region -911 to -435, and +8 to +276, respectively. These results suggest that multiple regulatory factors are involved in the transcriptional regulation of the flt-1 gene expression in a cell type-specific, or a more ubiquitous manner.

Base Sequence↗

PubMed1996

Bifrontal basal interhemispheric approach to craniopharyngioma resection with or without division of the anterior communicating artery.

The authors describe the use of a bifrontal basal interhemispheric approach with or without division of the anterior communicating artery (ACoA) for removal of large craniopharyngiomas. This approach is a more basal modification of the anterior interhemispheric approach; allowing preservation of most bridging veins. Since 1988, 22 patients underwent operations using this approach to achieve total or near-total excision of large craniopharyngiomas. Division of the ACoA was performed in 11 of 17 patients with retrochiasmatic tumors with no early or late complications related to division of the artery. There were no operative mortalities. Visual improvement (59%) and preservation of the pituitary stalk (64%) were achieved in a high percentage of patients. Preservation of the pituitary stalk correlated well with postoperative pituitary function. The bifrontal basal interhemispheric approach allowed a bilateral, wider operative field with better orientation and views of important neural structures and perforating arteries without requiring combination with other approaches. When the ACoA limited operative exposure, the artery could be divided safely. The authors discuss indications for, and advantages of, the bifrontal basal interhemispheric approach with or without division of the ACoA in the removal of large craniopharyngiomas.

Adolescent↗

PubMed1996

[Interphase cytogenetics of the breast tumors with fluorescence in situ hybridization (FISH) on cytologic preparation--its practice and clinical applications].

Fluorescence in situ hybridization (FISH) study with the chromosome specific probes is performed in the interphase nuclei of the routinely processed cytologic preparation of the breast tumors. Numerical aberrations on the chromosomes 1, 3, 11 or 17 were detected in more than 80% of the malignant tumors, but not in the benign tumors. Marked heterogeneity of the polysomies is noted in the malignant tumor cells. A few malignant cases revealed monosomy of chromosome 17. No apparent correlation between the numerical abnormalities and the histological features in malignant tumors is identified. These results suggest that the interphase cytogenetics with FISH for the breast tumors may be useful for differential diagnosis of malignancy. The practice and the clinical applications of the FISH study are discussed.

Biopsy, Needle↗