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Biomedical subjects

M Shibuya

Publications and source records attributed to M Shibuya.

At least 235 records · Page 13Linked to original sources
PubMed1995

Augmented lung adenocarcinoma cytotoxicity by the combination of a genetically modified anti-Lewis Y antibody and antibodies to complement regulatory proteins.

Complement-dependent cytotoxicity (CDC) mediated by a chimeric anti-Lewis Y monoclonal antibody (cH18A; human IgG1) was investigated in this study. Human lung adenocarcinoma cell lines (PC7, PC9, and PC14) were used as the target cells. PC7 and PC9 cells, expressed Lewis Y antigen and were lysed by cH18A as effectively as by the parent mouse anti-Lewis Y antibodies (mH18A) in a concentration-dependent manner. PC14 cells did not express Lewis Y antigen and were not lysed by either cH18A or mH18A. cH18A mediated CDC activity against PC7 and PC9 cells was enhanced by the combined use of monoclonal antibodies directed against CD46(MCP), CD55(DAF), and CD59. These molecules are complement-regulatory proteins which protect host cells from CDC. PC7 and PC9 cells, showed high levels of surface expression of these proteins, PC7 cells were more susceptible to cH18A-mediated CDC than PC9 cells. Use of multiple blocking antibodies to the complement-regulatory proteins produced more enhancement of cH18A-mediated CDC than a single antibody. Moreover, expression of CD55 and CD59 by PC7 and PC9 cells was decreased after treatment with PI-PLC, resulting in increased susceptibility to cH18A-mediated CDC. Although the reason is unknown, PC7 cells became more susceptible to CDC than PC9 cells after PI-PLC treatment even in the absence of cH18A. These data suggest that chimeric monoclonal antibodies can be used to induce CDC against lung adenocarcinoma, and that such CDC is potentiated by a variety of antibodies blocking compliment-regulatory proteins on the tumour cell surface.

Adenocarcinoma↗
PubMed1995

Tyrosine phosphorylation of BCR by FPS/FES protein-tyrosine kinases induces association of BCR with GRB-2/SOS.

The human bcr gene encodes a protein with serine/threonine kinase activity, CDC24/dbl homology, a GAP domain, and an SH2-binding region. However, the precise physiological functions of BCR are unknown. Coexpression of BCR with the cytoplasmic protein-tyrosine kinase encoded by the c-fes proto-oncogene in Sf-9 cells resulted in stable BCR-FES protein complex formation and tyrosine phosphorylation of BCR. Association involves the SH2 domain of FES and a novel binding domain localized to the first 347 amino acids of the FES N-terminal region. Deletion of the homologous N-terminal BCR-binding domain from v-fps, a fes-related transforming oncogene, abolished transforming activity and tyrosine phosphorylation of BCR in vivo. Tyrosine phosphorylation of BCR in v-fps-transformed cells induced its association with GRB-2/SOS, the RAS guanine nucleotide exchange factor complex. These data provide evidence that BCR couples the cytoplasmic protein-tyrosine kinase and RAS signaling pathways.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Central cardiovascular effects induced by intracisternal PACAP in dogs.

The cardiovascular responses to intracisternally administered pituitary adenylate cyclase-activating polypeptide (PACAP) were investigated and compared with those of vasoactive intestinal peptide (VIP) in anesthetized dogs. Intracisternal administration of 10 nmol of PACAP-27 increased mean arterial blood pressure (MABP) significantly with a simultaneous increase of plasma arginine vasopressin and epinephrine concentrations. Intracisternal administration of VIP increased plasma arginine vasopressin concentration significantly but caused no appreciable change in MABP. Systemic infusion of the nonpeptide vasopressin V1 receptor antagonist OPC-21268 did not inhibit the PACAP-27-induced increase in MABP, whereas phentolamine, an alpha-adrenoceptor blocker, reversed the increase. Intracisternal pretreatment with the vasopressin V1 receptor antagonist [Pmp1, Tyr(Me)2]Arg8-vasopressin also inhibited the increase. These findings suggest that PACAP has a central pressor action by increasing sympathetic outflow, which is probably mediated by the vasopressinergic neural network. PACAP seems to play important roles in hormonal and neural control of systemic circulation.

Adrenergic alpha-Antagonists↗
PubMed1995

Stimulation by thyroid-stimulating hormone and Grave's immunoglobulin G of vascular endothelial growth factor mRNA expression in human thyroid follicles in vitro and flt mRNA expression in the rat thyroid in vivo.

To elucidate the pathogenesis of thyroid gland hypervascularity in patients with Graves' disease, we studied the expression of mRNAs for vascular endothelial growth factor (VEGF) and its receptor, Flt family, using human thyroid follicles in vitro and thiouracil-fed rats in vivo. Human thyroid follicles, cultured in the absence of endothelial cells, secreted de novo-synthesized thyroid hormone in response to thyroid-stimulating hormone (TSH) and Graves' IgG. The thyroid follicles produced VEGF mRNA but not flt-1 mRNA. The expression of VEGF mRNA was enhanced by insulin, tumor-promoting phorbol ester, calcium ionophore, dibutyryl cAMP, TSH, and Graves' IgG. When rats were fed thiouracil for 4 wk, their serum levels of TSH were increased at day 3. VEGF mRNA was also increased on day 3, accompanied by an increase in flt family (flt-1 and KDR/ flk-1) mRNA expression. These in vitro and in vivo findings suggest that VEGF is produced by thyroid follicles in response to stimulators of TSH receptors, via the protein kinase A and C pathways. VEGF, a secretable angiogenesis factor, subsequently stimulates Flt receptors on endothelial cells in a paracrine manner, leading to their proliferation and producing hypervascularity of the thyroid gland, as seen in patients with Graves' disease.

Animals↗
PubMed1995

The use of self-retaining retractors in surgery for spinal cord tumors: technical note.

Self-retaining retractors may be useful in spinal tumor surgery. In this study, the tumors were retracted away from the surrounding tissue by pronged hooks attached to flexible self-retaining retractors; by this process, we could avoid placing pressure on the spinal cord. A clear dissection plane was exposed between the underside of the tumor and the surrounding spinal cord, so that the surgeon had both hands free to perform the operation. Two retractor base systems were used: 1) Sugita's multipurpose headframe for the cervical region, and 2) a newly designed U-shaped, table-fixed retractor base for the thoracic and lumbosacral regions. Most retracting instruments used in cranial surgery can be used with either system.

Humans↗
PubMed1995

Molecular cloning of cDNA encoding human lanosterol synthase.

A cDNA encoding human lanosterol synthase, the enzyme responsible for the backbone formation step in sterol biosynthesis, was cloned by extensive application of PCRs. Five degenerate oligonucleotide primers (139S, 440S, 528A, 575A and 712A) corresponding to the homologous amino acid sequences among the known 2,3-oxidosqualene cyclase(OSC) were designed. PCR with one pair(440S and 528A) of five primers yielded a 285-bp fragment. PCRs with the primers based on the obtained fragment and the degenerate primers (139S and 712A) gave longer fragments. Finally, full nucleotide sequence of cDNA was obtained by a "rapid amplification of cDNA ends" (RACE) method.

Amino Acid Sequence↗
PubMed1995

Molecular cloning of cDNA encoding rat 2,3-oxidosqualene: lanosterol cyclase.

A cDNA encoding rat 2,3-oxidosqualene: lanosterol cyclase, the enzyme responsible for the complex cyclization/rearrangement step in sterol biosynthesis, was cloned by extensive application of PCRs. Oligonucleotide primers were designed in sense and anti-sense directions corresponding to internal peptide sequences of purified enzyme. Successive PCRs with all possible combinations of these primers yielded a 178-bp fragment, and based on its sequence full nucleotide sequence of cDNA was obtained by a "rapid amplification of cDNA ends" (RACE) method.

Amino Acid Sequence↗
PubMed1995

[Effect of anticancer drugs on invasive capacity of human small-cell lung cancer cells in vitro].

The effect of anticancer drugs on invasive capacity of Lu 135 human small-cell lung cancer cells was studied in vitro. the invasive capacity decreased in a dose-dependent manner when tumor cells were treated with the anticancer drugs cisplatin and etopside. The inhibition of tumor cell invasion was almost parallel with the inhibition of tumor cell growth. The anticancer drugs also suppressed tumor cell migration and the activity of the matrix-degrading protease, type IV collagenase, activity. But they did not suppress adhesion to basement membrane protein such as laminin, fibronectin, or type IV collagen. Because tumor cells express adhesion molecules on the cell surface, the effect of the anticancer drugs on the expression of one such molecule, integrin, was also studied. Lu 135 cells expressed alpha 4/beta 1 integrin on the cell surface, and the pattern of integrin expression did not change with exposure with the anticancer drugs. These data suggest that the anticancer drugs inhibit the invasive capacity by suppression of migration and type IV collagenase activity of tumor cells, and that they do not modulate adhesion to the extracellular matrix or cell surface adhesion molecules such as integrin. Furthermore, these findings indicate that anticancer drugs may be useful for anti-metastatic therapy in patients with small-cell lung cancer.

Antineoplastic Agents↗
PubMed1995

False traumatic aneurysm of the dorsal wall of the supraclinoid internal carotid artery--case report.

A 32-year-old male presented with subarachnoid hemorrhage following head trauma. Initial carotid angiography revealed an aneurysm protruding from the dorsal wall of the supraclinoid internal carotid artery. Two weeks later, following two additional hemorrhagic episodes, repeat carotid angiography showed severe vasospasm and dramatic expansion of the aneurysm. He died 17 days after the accident. Autopsy and histological examination confirmed the diagnosis of a traumatic, false aneurysm of the internal carotid artery. Improved prognosis requires early recognition and surgical obliteration of such aneurysms.

Accidents, Traffic↗
PubMed1995

Monitoring visual evoked potentials during retraction of the canine optic nerve: protective effect of unroofing the optic canal.

To evaluate the effects of unroofing the optic canal during retraction of the optic nerve, the authors monitored changes in visual evoked potentials (VEPs) stimulated by a light-emitting diode in the canine model. At rest, an early VEP wave was reliably observed with an amplitude of 8.2 +/- 0.6 microV and a latency of 51.5 +/- 0.7 msec; this wave was named N50. The intracranial optic nerve was retracted using a weight of 5, 10 or 50 g. The earliest change in VEP noted during retraction was a reduction in N50 wave amplitude. The length of time required until N50 amplitude decreased to 50% of the control group (T50) was 10.7 +/- 1.8 minutes with a weight of 5 g, 4.9 +/- 0.7 minutes with 10 g, and 2.9 +/- 0.4 minutes with 50 g, with statistically significant differences between the groups. Retraction of the optic nerve with all weights finally resulted in the disappearance of the N50 wave. The amplitude of the N50 wave recovered fully to control size when retraction was released immediately after the wave disappeared. The time course of amplitude recovery did not differ significantly between groups. Unroofing the optic canal prolonged the T50 during retraction significantly to 20.7 +/- 2.9 minutes with a weight of 5 g, 18.9 +/- 4.2 with 10 g, and 9.0 +/- 2.4 with 50 g. These results demonstrate that unroofing the optic canal can protect the optic nerve from damage during operations that require optic nerve retraction.

Animals↗
PubMed1995

[Relation between preoperative ventricular arrhythmias and postoperative results in aortic valve regurgitation].

Sudden death is a well known complication of aortic valve regurgitation and remains a common cause of late mortality after aortic valve replacement. Although malignant arrhythmias have been suggested as the cause of these outcome, there has been little information concerning the frequency and severity of ventricular arrhythmias in patients with aortic valve regurgitation. In order to evaluate the relation between the severity and/or frequency of ventricular arrhythmias and late postoperative results in patients with pure aortic valve regurgitation, 24-hour ambulatory electrocardiographic recordings were obtained before surgery in 107 patients without coronary artery disease. Grading of ventricular arrhythmias was based on a Lown method and compared with hemodynamic data. Ventricular premature beats were observed in 101 patients (94.4%) before operation. Multiformity was found in 10 patients (9.3%) couplets in 19 patients (17.8%) and ventricular tachycardia in 32 patients (29.9%). Patients with severe ventricular arrhythmias (Lown grade 3 or 4: 57.0%) had a higher left ventricular end systolic volume index (LVESVI) 153.1 +/- 76.4 ml/m2 vs 96.5 +/- 35.0 ml/m2 (p = 0.0001); a higher left ventricular end diastolic volume index (LVEDVI) 257.0 +/- 85.4 ml/m2 vs 206.5 +/- 58.3 ml/m2 (p = 0.0009); a lower left ventricular ejection fraction (LVEF) 43.4 +/- 12.5% vs 54.2 +/- 9.8% (p = 0.0001). LVESVI was not related to the severity of ventricular arrhythmias, but was significantly related to the frequency (p < 0.05). All patients with late death were belonging to Lown grade 3 or 4 in severity and more than 30 beats per hour in frequency (28.6%). This study indicates that ventricular arrhythmias are common in patients with aortic valve regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1995

Abundant expression of translation initiation factor EIF-4E in post-meiotic germ cells of the rat testis.

BACKGROUND: Eukaryotic translation initiation factor EIF-4E is a key component in the regulation of translational efficiency of MRNAs and its increased expression may accelerate cell growth and division. EIF-4E has the potential to transform rat embryo fibroblast cells by cooperation with v-Myc or adenovirus E1A. Our previous study showed that a variety of tumor cells examined exhibited elevated levels of eIF-4E gene expression. Thus it is thought that overexpression of EIF-4E can result in aberrant growth and cell transformation. EXPERIMENTAL DESIGN: To characterize rat EIF-4E, a clone containing rat eIF-4E cDNA was isolated from a rat testis cDNA library by screening with a synthetic probe prepared by the reverse transcription-polymerase chain reaction (RT-PCR) method. Based on the conserved nucleotide sequences between mouse and human eIF-4E cDNA, two oligonucleotide primers for RT-PCR were synthesized chemically. The cloned cDNA was sequenced and used as a probe for analysis of the expression level of eIF-4E mRNA in normal, differentiated rat tissues by Northern blot analysis. In situ hybridization analysis with digoxigenin-labeled antisense eIF-4E RNA as a probe was carried out to identify the eIF-4E-expressing sites in rat tissues. In addition, to analyse the phosphorylation level of EIF-4E, the proteins were fractionated from rat tissues by affinity column chromatography followed by isoelectric focusing (IEF)-gel electrophoresis. RESULTS: The nucleotide sequence of the eIF-4E cDNA is highly conserved in human, rat, and mouse. Extraordinarily elevated expression, more than 50-fold compared with that in the adult rat prostate, of eIF-4E was observed in testicular germ cells of rats of reproductive age, which was much greater than that in any tumor cell lines examined so far. The amount of EIF-4E fractionated from the adult rat testis was approximately 10 times higher than that from the adult rat liver. At least half of the purified testicular EIF-4E proteins were phosphorylated, a ratio similar to that in other rat tissues such as liver. In situ hybridization analysis demonstrated that elevated expression of eIF-4E mRNA was mainly observed in post-meiotic germ cells. CONCLUSIONS: Full activity of EIF-4E in translation requires the phosphorylation of the protein on a specific serine residue. Thus the elevated level of EIF-4E observed in the adult rat testis should be reflected in increase of the functional activity of EIF-4E. Based on the results of in situ hybridization analysis and characterization of EIF-4E, it was concluded that abundant EIF-4E in the testis may play an important role in spermatogenesis through translational regulation of stage-specific mRNAs during germ cell development.

Amino Acid Sequence↗
PubMed1995

Determination of growth fraction index in mammary carcinoma using MIB-1 monoclonal antibody: estimation of whole tumor proliferative potential using biopsy specimens.

We labeled the Ki-67 antigen in mammary carcinomas, using a MIB-1 monoclonal antibody, to evaluate the usefulness of MIB-1 Ki-67 Growth Fraction Indices (GFI; number of Ki-67 positive cells/total number of cells) of biopsy specimens in estimating the proliferative potential of the carcinomas. Formalin-fixed paraffin sections prepared from biopsy material, primary tumors, and axillary lymph nodes of ten invasive mammary carcinomas were chosen for immunohistochemical study. Bound antibody was detected using the avidin-biotin-complex peroxidase method. The GFI of the resected mammary carcinomas was similar to the estimated values based on the GFI of the biopsy specimens. The GFIs of the metastatic nodes in seven of the carcinomas were similar to those of the primary carcinomas, whereas two carcinomas yielded significantly different GFIs in the metastatic foci. These results suggest that the GFI of a mammary carcinoma biopsy specimen may reflect the proliferative ability of the whole carcinoma.

Adult↗
PubMed1994

Different signal transduction properties of KDR and Flt1, two receptors for vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) is a homodimeric peptide growth factor which binds to two structurally related tyrosine kinase receptors denoted Flt1 and KDR. In order to compare the signal transduction via these two receptors, the human Flt1 and KDR proteins were stably expressed in porcine aortic endothelial cells. Binding analyses using 125I-VEGF revealed Kd values of 16 pM for Flt1 and 760 pM for KDR. Cultured human umbilical vein endothelial (HUVE) cells were found to express two distinct populations of binding sites with affinities similar to those for Flt1 and KDR, respectively. The KDR expressing cells showed striking changes in cell morphology, actin reorganization and membrane ruffling, chemotaxis and mitogenicity upon VEGF stimulation, whereas Flt1 expressing cells lacked such responses. KDR was found to undergo ligand-induced autophosphorylation in intact cells, and both Flt1 and KDR were phosphorylated in vitro in response to VEGF, however, KDR much more efficiently than Flt1. Neither the receptor-associated activity of phosphatidylinositol 3'-kinase nor tyrosine phosphorylation of phospholipase C-gamma were affected by stimulation of Flt1 or KDR expressing cells, and phosphorylation of GTPase activating protein was only slightly increased. Members of the Src family such as Fyn and Yes showed an increased level of phosphorylation upon VEGF stimulation of cells expressing Flt1 but not in cells expressing KDR. The maximal responses in KDR expressing porcine aortic endothelial cells were obtained at higher VEGF concentrations as compared to HUVE cells, i.e. in the presence of Flt1. This difference could possibly be explained by the formation of heterodimeric complexes between KDR and Flt1, or other molecules, in HUVE cells.

Actins↗
PubMed1994

Correlation between the bromodeoxyuridine labeling index and the MIB-1 and Ki-67 proliferating cell indices in cerebral gliomas.

BACKGROUND: Recently, it has been shown that heating paraffin embedded tumor sections in a microwave oven can reactivate an epitope of Ki-67 protein that is recognized by the monoclonal antibody MIB-1. With this technique, a close correlation was shown between the bromodeoxyuridine labeling index (BUdR LI) and the MIB-1 proliferating cell index (PCI) in corresponding regions of glioblastomas. METHODS: The reliability of the MIB-1 PCI as a marker of proliferation was evaluated in 90 cerebral gliomas. The MIB-1 immunostaining of ethanol-fixed, paraffin embedded sections of 23 moderately anaplastic astrocytomas, 22 highly anaplastic astrocytomas, 30 glioblastomas, and 15 mixed malignant gliomas was compared with the BUdR LI and, in some cases, the Ki-67 PCI. RESULTS: MIB-1 positive cells were detected easily in the majority of the cases, and the MIB-1 immunostaining was often superior to that of Ki-67 in individual tumors. The MIB-1 PCI was significantly higher than the Ki-67 PCI and the BUdR LI. Linear-regression analysis showed significant correlations among the three indices. The MIB-1 PCI was correlated with the BUdR LI in each group of the astrocytic tumors and mixed malignant gliomas; the MIB-1 PCI was approximately 2.4-2.8 times higher than the BUdR LI. CONCLUSIONS: The close correlation between the MIB-1 PCI and the in vivo BUdR LI in serial sections of glioma subtypes suggests that MIB-1 immunostaining is a useful technique for analyzing the proliferative potential of individual gliomas.

Adult↗
PubMed1994

C3G, a guanine nucleotide-releasing protein expressed ubiquitously, binds to the Src homology 3 domains of CRK and GRB2/ASH proteins.

CRK protein, together with GRB2/ASH and Nck proteins, belongs to the adaptor-type Src homology (SH)2-containing molecules, which transduce signals from tyrosine kinases. Here another guanine nucleotide-releasing protein (GNRP), C3G, has been identified as a CRK SH3-binding protein. The nucleotide sequence of a 4.1-kb C3G cDNA contains a 3.2-kb open reading frame encoding a 121-kDa protein, and antibodies against C3G have been shown to detect a protein of 130-140 kDa. The carboxyl terminus of C3G has a peptide sequence homologous to GNRPs for Ras, and the expression of this carboxyl terminus region suppresses the loss of CDC25 function in the yeast Saccharomyces cerevisiae. The C3G protein expressed in Escherichia coli binds to CRK and GRB2/ASH proteins. Mutational analysis of C3G assigns the SH3 binding region to a 50-amino acid region containing a proline-rich sequence. The mRNAs of both the C3G and CRK proteins are expressed ubiquitously in human adult and fetal tissues. The results of these studies suggest that the complex of CRK and C3G, or GRB2/ASH and C3G, may transduce the signals from tyrosine kinases to Ras in a number of different tissues.

Adaptor Proteins, Signal Transducing↗
PubMed1994

Epidermal growth factor-receptor mutant lacking the autophosphorylation sites induces phosphorylation of Shc protein and Shc-Grb2/ASH association and retains mitogenic activity.

Epidermal growth factor (EGF) receptor (EGFR) can induce cell growth and transformation in a ligand-dependent manner. To examine whether the autophosphorylation of EGFR correlates with the capacity of the activated EGFR to induce cell growth and transformation, we truncated the human EGFR just after residue 1011, removing all three major autophosphorylation sites (DEL1011). Further, a point mutation was introduced at another autophosphorylation site, Tyr-992-->Phe (DEL1011+F992). The wild-type and mutant receptors were stably expressed in a NIH 3T3 variant cell line that expresses an extremely low level of endogenous EGFR and does not grow with EGF. As expected, DEL1011 and DEL1011+F992 were found to be severely impaired in EGF-induced autophosphorylation, due to the deletion of the appropriate target tyrosines. However, mutant receptors still could induce EGF-dependent DNA synthesis, morphological transformation, and anchorage-independent growth, although the extent of these was significantly reduced when compared with wild-type EGFR. EGF-induced tyrosine phosphorylation of Ras-GTPase activating protein-associated protein p62 and phospholipase C gamma 1 was dramatically reduced in the cells expressing DEL1011 and DEL1011+F992. On the other hand, tyrosine phosphorylation of Shc, complex formation of Shc-Grb2/Ash, and activation of microtubule-associated protein kinase were still fully induced upon EGF stimulation without binding of Shc or Grb2/Ash to the mutant receptor. Thus, tyrosine phosphorylation of Shc may play a crucial role for activating Ras and generating mitotic signals by the activated EGFR mutant.

3T3 Cells↗