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Biomedical subjects

M Shibuya

Publications and source records attributed to M Shibuya.

At least 415 records · Page 23Linked to original sources
PubMed1986

Neoplastic transformation of rat 3Y1 cells by a transcriptionally activated human c-myc gene and stabilization of p53 cellular tumor antigen in the transformed cells.

Transformed foci were obtained in rat 3Y1 fibroblasts cotransfected with pRmyc 27 (transcriptionally activated c-myc) and pSV2neo DNA. RmycY cell lines (1 to 7) were established from these foci. RmycY cells were small and round and contained enlarged nucleoli in the nucleus. The myc gene was expressed in these cell lines at a much higher level than in 3Y1 cells and at a level similar to that in HL-60 cells. These cell lines formed colonies in soft-agar culture and tumors in syngeneic rats transplanted with RmycY cells. Expression of the gene and colony formation in soft-agar culture were analyzed in subclones from RmycY cell line 1. A correlation between myc gene expression and the ability to form colonies in soft-agar culture was observed in these cells. Antibody against p53 cellular tumor antigen was detected in some sera from tumor-bearing rats. p53 cellular tumor antigen stabilized and accumulated in RmycY cells to the same extent as in simian virus 40-transformed cells. The results suggest that elevated c-myc expression and an increased amount of p53 cause 3Y1 cells to become a more tumorigenic cell line.

Animals↗
PubMed1986

Proto-oncogene c-ros codes for a molecule with structural features common to those of growth factor receptors and displays tissue specific and developmentally regulated expression.

A recombinant DNA clone containing cellular sequences homologous to the transforming sequence, v-ros, of avian sarcoma virus UR2 was isolated from a chicken genomic DNA library. Heteroduplex mapping and nucleotide sequencing reveal that the v-ros sequences are distributed in nine exons ranging from 65 to 204 nucleotides on cellular ros (c-ros) DNA over a range of 11 kilobases. Comparison of the deduced amino acid sequences of c-ros and v-ros shows two differences: v-ros contains a three-amino-acid insertion within the hydrophobic domain presumed to be involved in membrane association, and (ii) the carboxyl 12 amino acids of v-ros are completely different from those of the deduced c-ros sequence. The deduced amino acid sequence of c-ros bears striking structural features similar to those of insulin and epidermal growth factor receptors, including the presumed hydrophobic membrane binding domain, amino acids flanking the domain, and the distance between the domain and the catalytic region of the kinase activity. The expression of c-ros appears to be under a very stringent control. When tissues at various stages of chicken development were analyzed, only kidney was found to contain a significant level of c-ros RNA. The level of c-ros RNA in kidney tissue is most abundant in 7- to 14-day-old chickens. Finally, nucleotide sequences of c-ros DNA and UR2-associated helper viral genome at regions corresponding to the gag ros recombination site suggest that the junction has been formed by RNA splicing.

Amino Acid Sequence↗
PubMed1986

Human c-ros-1 gene homologous to the v-ros sequence of UR2 sarcoma virus encodes for a transmembrane receptorlike molecule.

We isolated a human gene (designated c-ros-1) homologous to the v-ros sequence of UR2 sarcoma virus. Ten exons, 1,414 base pairs spanning 26 kilobases, contained a tyrosine kinase domain, a transmembrane domain, and a part of an extracellular domain carrying an N glycosylation site which was not acquired by UR2 sarcoma virus. The predicted structure of c-ros-1 is unique among the src family and clearly distinct from the human insulin receptor.

Amino Acid Sequence↗
PubMed1986

The effects of HA compound calcium antagonists on delayed cerebral vasospasm in dogs.

The authors have examined the effects of the HA compounds HA1004(N-(2-guanidinoethyl)-5-isoquinolinesulfonamide) and HA 1077(1-(5-isoquinolinesulfonyl)homopiperazine), which are intracellular calcium antagonists, on delayed cerebral vasospasm from subarachnoid hemorrhage (SAH). The modes of action of these compounds were compared with those of the more commonly used calcium entry blockers. Calcium ionophore A23187 (4.8 X 10(-6) M)-induced contraction of a canine basilar artery strip was completely antagonized by the HA compounds (10(-5) M) but not by the entry-blocking calcium antagonists nicardipine, diltiazem, and verapamil (10(-5) M), suggesting that the HA compounds act differently. Delayed cerebral vasospasm was induced by a "two-hemorrhage" canine model. The magnitude of the vasospasm and the effects of the HA compounds were determined angiographically. On SAH Day 7, a significant vasospasm was observed in every dog. The diameter of the basilar artery had diminished to 59% +/- 2% (mean +/- standard error) of the control value obtained before SAH (on Day 1). The intravenous administration of HA 1004 caused a mild dilation of the basilar artery of 10% and 11% at doses of 3 and 10 mg/kg, respectively; however, HA 1077 produced a more marked dilation of 19% and 27%, respectively, at the same doses. Both of these drugs lowered mean arterial blood pressure to about 80% and 50% at doses of 3 and 10 mg/kg, respectively. Intracisternal administration of the HA compounds (6 mg) completely reversed cerebral vasospasm without much effect on the blood pressure. The intracellular calcium antagonists of the HA compound group appear to be promising agents for the treatment of intractable cerebral vasospasm.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1986

Analysis of structure and activation of some receptor-type tyrosine kinase oncogenes.

We first describe the characterization of proto-oncogene of v-ros in chicken and human genomes. v-ros sequence of UR2 avian sarcoma virus carries a hydrophobic short stretch upstream of the kinase domain, suggesting that its proto-oncogene encodes for a receptor molecule. Using v-ros DNA as a probe we isolated chicken and human c-ros proto-oncogenes. These c-ros DNAs contained a tyrosine kinase domain, transmembrane domain and a part of an extracellular domain carrying an N glycosylation site which was not acquired by UR2 sarcoma virus. These results strongly suggest that proto-oncogene c-ros encodes for a receptor of cell growth or differentiation factor(s) and that the v-ros sequence is a truncated form of this receptor molecule. Structural alteration and overexpression under the control of viral promoter may be crucial for transforming activity of v-ros gene. We then report another example where a receptor-type oncogene is qualitatively and quantitatively activated. By screening with various onc probes we detected two human glioblastomas which have amplification of structurally altered c-erbB1 (epidermal growth factor (EGF) receptor) gene. c-erbB1 gene in these tumors bears a small deletion within the extracellular domain, and the gene product 140 kd protein shorter than the normal 170 kd EGF receptor was heavily phosphorylated on tyrosine residue even without ligand in in vitro phosphorylation reaction. Thus, these mutated EGF receptors seem to be fixed as a "switch-on" form in signal transduction for cell growth and might be involved in the transformation of glial cells.

Amino Acid Sequence↗
PubMed1986

[Immunohistochemical study of subependymal giant cell tumor associated with tuberous sclerosis].

Subependymal giant cell tumors from four patients associated with tuberous sclerosis were examined by peroxidase antiperoxidase (PAP) immunohistochemistry for neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP) and S-100 protein. The tumor cells were grouped into three morphological types: ganglion-like pyramidal cells, swollen gemistocytic cells and fibrillated spindle cells. There was little difference in immunohistochemical property between these cell types in each case, suggesting that the tumor cells of different cell types have a same origin. The majority of the tumor cells was intensely stained for NSE in every case. On the other hand, for GFAP none of the tumor cells was stained in two cases, and the minority was weakly stained in the other two cases. The intensity of staining of the tumor cells for S-100 protein varied from case to case. Our findings together with those of others show the definite immunohistochemical characteristics of subependymal giant cell tumors with tuberous sclerosis, i.e., strong positivity for NSE in contrast to their negativity or weak positivity for GFAP. However, these findings do not necessarily suggest that the tumor is of neuronal origin, because in the case of neoplasms the significance of the presence of NSE as indicative of neuronal origin is open to question.

Adolescent↗
PubMed1986

[Renal tubular impairment in traumatized patients].

Urinary beta 2-microglobulin (beta 2M) and N-acetyl-beta-D-glucosaminidase (NAG) in addition to conventional renal parameters such as creatinine clearance (Ccr), free water clearance (CH2O) and fractional excretion of sodium (FENa) were measured in 79 traumatized patients. These patients were separated into two groups, one with shock on admission (N = 43). In patients with shock, CH2O, FENa and urinary excretion of Beta 2M and NAG indicated abnormal levels correlating with impairment of Ccr, inspite of adequate urine output, on the day of trauma. Even in patients without shock, urinary Beta 2M and/or NAG increased without impairment of urine output, Ccr, CH2O and FENa, and did not return to normal level during the following 7 days. The results suggest a liability to damage and the delayed improvement of renal tubulus in traumatized patients.

Acetylglucosaminidase↗
PubMed1986

Cleavage of DNA by model complexes of cytochrome P-450.

Thiolate-hemin complexes as chemical models for cytochrome P-450 have been shown to cause cleavage of DNA. The cleavage of DNA to open-circular and linear forms depended on the structure of thiol ligand and the thiol ligand:hemin ratio at pH 7.8. Complete cleavage of DNA was observed by complexes containing thioglycolate ethylester and mercaptoethanol at 400-600 moles excess of thiol ligand to hemin, those containing cysteine, cysteine methylester and cysteine ethylester at 50-200 moles excess, and those containing mercaptopropionylglycine, glutathione, glutathione dimethylester, penta- and nonapeptides at 5-100 moles excess. Inhibition experiments suggested the involvement of active oxygen species in the cleavage of DNA.

Cytochrome P-450 Enzyme System↗
PubMed1985

Long-term follow-up of patients with optic glioma.

Patients with optic glioma were classified into two types: infant type and childhood. The infant type was usually immature astrocytomas that had an aggressive course and had a poor prognosis. On the other hand, the childhood type was usually mature astrocytomas with a rather benign, self-limiting course, even when the tumor had been left untreated. To make a long-term assessment, 11 patients with optic glioma were studied and 6 long-term survivors with chiasmal tumor invasion, in whom total removal of the tumor had not been feasible, were followed up for 8-12 years. Most of them had a stable course both clinically and radiologically.

Adolescent↗
PubMed1985

Fluorescent pigments by covalent binding of lipid peroxidation by-products to protein and amino acids.

The fluorescent products formed on reaction of 12-oxo-cis-9-octadecenoic acid (12-keto-oleic acid) with about 20 different amino acids, polylysine and bovine serum albumin (BSA) were studied. Besides glycine, only the basic amino acids histidine, lysine and arginine gave products with strong fluorescence. N-Acetylation of amino acids greatly reduced the fluorescence of their reaction products. The formation of fluorescent products was inhibited strongly by SH-amino acids such as N-acetyl-cysteine and glutathione. Polyacrylamide gel electrophoresis showed that BSA treated with 12-keto-oleic acid was more acidic than untreated or ricinoleic acid-treated BSA, indicating that basic amino acid residues in BSA were modified by reaction with the keto fatty acid. None of the structural analogs of 12-keto-oleic acid tested--12-oxo-trans-10-octadecenoic acid, 12-oxo-octadecanoic acid, 12-hydroxy-cis-9-octadecenoic acid (ricinoleic acid), cis-9-octadecenoic acid (oleic acid) and linoleic acid--reacted with glycine to give a fluorescent product. The fluorescent products formed on reaction of 12-keto-oleic acid methyl ester with benzyl amine and glycine methyl ester were shown to be 8-(N-substituted-4,5-dihydro-4-oxo-5-hexyl-5-hydroxy-2-pyrrolyl) octanoic acid methyl esters. The fluorescence properties of these compounds were attributed to the chromophobic system NC = CC = O which contains 6 pi electrons. This investigation contributes to insight of the mechanism of formation of fluorescent pigments, probably by a similar reaction of other compounds of the beta, gamma-unsaturated carbonyl type.

Amino Acids↗