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Biomedical subjects

M Shibuya

Publications and source records attributed to M Shibuya.

At least 325 records · Page 18Linked to original sources
PubMed1991

Isolation and characterization of cDNA for an androgen-regulated mRNA in the flank organ of hamsters.

Flank organs of hamster are useful for studying androgen-dependent growth of hair follicles and sebaceous glands. To elucidate the mechanism of gene expression regulated by androgen, we constructed a cDNA library from flank organs of male hamsters and screened by a differential hybridization method using cDNA probes from normal and castrated males. We isolated a cDNA clone, termed FAR-17a, whose expression was found to be highly sensitive to androgen. FAR-17a mRNA of 1.8 kb was reduced after castration and reappeared after testosterone treatments. Among several tissues examined, FAR-17a gene was expressed at a high level in flank organ and a low level in testis and earlobe. FAR-17a probe detected a few fragments in genomic DNA of hamster, mouse, suncus, pig, and human, suggesting that this gene is phylogenetically conserved. The sequence of FAR-17a cDNA predicts a protein of 231 amino acids (27,216 daltons) having basic properties. The deduced protein has no significant homologies to proteins previously described.

Amino Acid Sequence↗
PubMed1991

Blockade of intracellular actions of calcium may protect against ischaemic damage to the gerbil brain.

1. The brain cytoprotective effects of a putative calcium-associated protein kinase inhibitor, HA1077, as well as a calcium entry blocker nicardipine were evaluated in models of cerebral ischaemia in Mongolian gerbils. Morphological changes characterizing delayed neuronal death of selectively vulnerable CA1 pyramidal neurones in the hippocampus of the Mongolian gerbil brain occurred 7 days after transient bilateral occlusion of the common carotid arteries. 2. A single injection of HA1077 (1 and 3 mg kg-1, i.p.) 5 min after the occlusion led to a dose-dependent protection of the CA1 neurones. Repeated administrations of HA1077 (1 and 3 mg kg-1, i.p., twice daily for 7 days post-ischaemia) revealed an increase in the number of normal cells, compared to findings with a single administration. 3. In contrast to HA1077, nicardipine (0.3 and 1 mg kg-1, i.p.) did not reduce neuronal degeneration. 4. HA1077 did not interact with the ion channel within which MK-801 binds, as determined by receptor binding. 5. The calcium ionophore, A23187, caused a tonic contraction in canine cerebral arterial strips. HA1077, but not nicardipine, relaxed the A23187-induced contraction, concentration-dependently. 6. These results suggest that blockade of the intracellular actions of calcium may provide protection against ischaemic damage in the brain.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Unregulated expression of the erythropoietin receptor gene caused by insertion of spleen focus-forming virus long terminal repeat in a murine erythroleukemia cell line.

A murine erythroleukemia (MEL) cell line, F5-5, expressed 10,000 binding sites for erythropoietin (EPO) per cell, 10-fold more than was expressed by other murine erythroleukemia cell lines and normal erythroid progenitors. Northern (RNA) and Southern blot analyses revealed overexpression of mRNA for the EPO receptor (EPOR) and rearrangement of one of the EPOR gene alleles in F5-5 cells, respectively. Molecular cloning of F5-5-derived cDNA encoding EPOR revealed that the 5' noncoding region of the EPOR cDNA corresponds to the 3' long terminal repeat sequence of the polycythemic strain of Friend spleen focus-forming virus (F-SFFVP). The aberrant EPOR transcripts containing the 3' long terminal repeat sequence were mainly expressed in F5-5 cells. The same integration upstream of the EPOR gene was also observed in other subclones and the parent cell line. It is possible that overexpression of EPOR by viral promoter insertion will confer growth advantage to an F-SFFVP-infected erythroid progenitor cell, leading to positive clonal selection through further leukemogenic steps.

Amino Acid Sequence↗
PubMed1991

Isolation, sequence and bacterial expression of a cDNA for chalcone synthase from the cultured cells of Pueraria lobata.

cDNA clones for chalcone synthase (CHS) of Pueraria lobata cultured cells were isolated by screening the cDNA library using CHS cDNA of Phaseolus vulgaris as a probe. Analysis of nucleotide sequences of the cloned cDNA revealed a 1170-bp open reading frame that encoded a 390-amino acid polypeptide with an Mr of 43,000. The full-length cDNA was cloned into the expression vector pT7-7. CHS activity was found in the crude extracts of transformed E. coli after induction and two protein bands of ca. 43 and 34 kd were hybridized with anti-persley CHS antiserum.

Acyltransferases↗
PubMed1991

Synergistic action of phenolic signal compounds and carbohydrates in the induction of virulence gene expression of Agrobacterium tumefaciens.

Virulence (vir) gene expression of Agrobacterium tumefaciens is activated by plant phenolic compounds such as alpha-hydroxyacetosyringone (HOAS), acetosyringone (AS), methyl syringate, coniferyl alcohol and sinapyl alcohol. Inositol was found to be a potentiating factor of vir-inducing activity, which enhanced the vir-inducing activity of AS and HOAS in a synergistic manner, in particular at a low concentrations of AS and HOAS. Of the other sugars tested D-glucose, L-rhamnose, D-xylose and D-galacturonic acid, the main components of plant cell wall polysaccharides, remarkedly potentiated the vir-inducing activity of AS, indicating the cooperative action of the signal compounds and sugars in Agrobacterium infection to plants.

Agrobacterium tumefaciens↗
PubMed1991

Biologically active constituents of Arnebia euchroma: structure of arnebinol, an ansa-type monoterpenylbenzenoid with inhibitory activity on prostaglandin biosynthesis.

Three phenolic compounds were isolated from the roots of Arnebia euchroma as inhibitors of in vitro prostaglandin biosynthesis. Two known compounds were identified as shikonofurans and des-O-methyllasiodiplodin. The other new compound was named arnebinol and its structure was elucidated as a novel ansa-type monoterpenylbenzenoid derivative.

Animals↗
PubMed1991

Biologically active constituents of Arnebia euchroma: structures of new monoterpenylbenzoquinones: arnebinone and arnebifuranone.

Two quinonic compounds, arnebinone and arnebifuranone, were isolated from the roots of Arnebia euchroma and their structures were elucidated on the basis of spectral evidence. Arnebionone is a monoterpenyl-benzoquinone in which the monoterpene moiety forms a fused ring to the benzoquinone. Arnebifuranone is another monoterpenylbenzoquinone with a furan ring containing side chain which is bonded to the benzoquinone at the head carbon of C10 moiety originating from the geranyl moiety of geranylhydroquinone.

Animals↗
PubMed1991

Effect of dietary calcium on serum BGP (osteocalcin).

The present study was designed to clarify the effects of dietary calcium (Ca) intake on serum BGP (osteocalcin) levels. Twelve women with a mean age of 21.2 years participated in the study. After one week of normal Ca intake (mean +/- SE, 535 +/- 2 mg/day), a low-Ca diet (163 +/- 1 mg/day) was given for one further week. Additional asparagine Ca (3 g as Ca/day) was also given to half of the subjects. Serum total and ionized Ca concentrations as well as BGP, PTH and 1,25(OH)2D3 were measured at the end of each period. Amounts of Ca and hydroxyproline excreted in urine were also determined. The plasma level of ionized Ca was significantly increased without any change in total Ca in either group. Low and high Ca intake decreased and increased urinary Ca excretion by 28% and 56%, respectively. Serum levels of BGP and 1,25(OH)2D3 were significantly augmented along with a transient increase in urinary hydroxyproline excretion after Ca deprivation. These results suggest that serum BGP is increased after one week of Ca restriction in healthy subjects.

Adult↗
PubMed1991

Intraoperative protection of cranial nerves and perforating arteries by silicone rubber sheets. Technical note.

The authors describe a technique whereby, during microneurosurgery, vital structures are covered or wrapped with small pieces of silicone rubber sheeting to protect them from intraoperative injury. In this way, perforating arteries located behind a large aneurysm can be covered to avoid their inclusion within the blades of the clip, and the cranial nerves coursing around or through a tumor can be wrapped to protect them from injury by a suction or forceps. By insulating nerves and arteries, this silicone rubber sheet has the added advantage of protecting them from injury due to electrical current of bipolar forceps. The silicone rubber sheet described here is smoother, thinner, and lighter than a cotton pattie.

Cerebral Arteries↗
PubMed1991

[A case of retrovesical embryonal cell carcinoma].

We report a case of an extragonadal germ cell tumor in the retrovesical region. The patient complained of a perineal and micturition pain. Urethrography, CT and MRI showed a retrovesical tumor protruding into the bladder. Alfa-fetoprotein was increased to 12,170 ng/ml. Bilateral testes did not contain any palpable mass by careful palpation. No tumor was detected by ultrasonography, either. Clinically, he was diagnosed as having a retrovesical extragonadal germ cell tumor associated with paraaortic lymph-nodes and bilateral pulmonary metastases. Although he was treated by combination chemotherapy (PVB and VAB-6 regimen) and irradiation, he died of carcinomatosis about 6 months after the admission. There was no evidence of tumor in bilateral testes on autopsy. This case was a second case of extragonadal germ cell tumor originating from the retrovesical lesion in the literature.

Adult↗
PubMed1991

Metal- and photo-induced cleavage of DNA by podophyllotoxin, etoposide, and their related compounds.

Podophyllotoxin (PD) and its derivative etoposide (VP-16), a clinically useful anticancer drug, exhibit different mechanisms of action. PD binds specifically to tubulin to prevent its polymerization, whereas VP-16 lacks this action. The DNA strand breakage caused by VP-16 is thought to be due to its interaction with topoisomerase II or to free radical formation by oxidation of its 4'-phenolic hydroxyl group to a semiquinone free radical. We have demonstrated that PD, VP-16, 4'-demethylepipodophyllotoxin (DEPD), and syringic acid (SA) exhibit no DNA-cleaving activity but, in the presence of metal ions such as Cu2+ and Fe3+, DEPD and SA form metal complexes, which in turn show high activity for DNA strand scission at pH 7.8 under air. Furthermore, it was found that DNA cleavage was greatly promoted by irradiation with UV light. The PD-Fe3+ system at pH 7.8 showed very low DNA-cleaving activity, but irradiation with UV light in the system induced almost complete DNA breakage. DNA cleavages were significantly inhibited in the presence of hydroxyl radical scavengers, such as sodium benzoate and dimethylurea, in the Cu(2+)-SA and Fe(3+)-PD systems, with or without UV irradiation. These reactions were investigated by optical and ESR spectra, coupled with ESR spin-trapping techniques, by which the formation of hydroxy radicals was clearly detected in all systems. These findings have led us to a new proposal of the metal- and photo-induced mechanism for understanding the antitumor action of PD, VP-16, and their related compounds.

DNA↗
PubMed1991

[Transaortic repair of aortopulmonary septal defect in neonate (20 days of age, 2175 gram) using profoundly hypothermic circulatory arrest].

In a 20-days old girl, aortopulmonary septal defect (total defect type) was closed by transaortic patch repair with cardiopulmonary bypass (CPB). The postoperative course was uneventful, and she was discharged 43 days later. This is the youngest and lowest-weight case ever reported in Japan. Various procedures for aortopulmonary septal defect have been proposed with or without CPB. However, transaortic repair with the aid of profoundly hypothermic circulatory arrest seems to be the most preferable corrective surgery for total defect type of neonate and low-weight infant.

Aortopulmonary Septal Defect↗
PubMed1990

Endothelin: a potential modulator of cerebral vasospasm.

1-(5-Isoquinolinesulfonyl)-homopiperazine, HA1077, is a calcium antagonist with anti-vasospastic properties. This compound blocks intracellular actions of calcium in a variety of experiments. In the present study, we examined the effects of HA1077 on the vascular actions of endothelin, an endothelium-derived vasoactive peptide, in dogs in vitro and in vivo. Intracisternal injections of endothelin (0.01 nmol) produced a significant vasospasm, as measured by angiography, similar to that seen in the canine hemorrhage model. Infusion of HA1077 led to a significant dilatation of the spastic basilar artery in endothelin-treated dogs. The rank order of in vitro contractile activity in canine cerebral arteries was a stable thromboxane A2 analog greater than endothelin greater than 5-hydroxytryptamine greater than prostaglandin F2 alpha greater than histamine greater than noradrenaline. HA1077 effectively antagonized the endothelin-induced contraction of canine basilar arterial strips in both calcium-containing and calcium-free medium. The present results indicate that HA1077 is an effective antagonist for endothelin in vitro and in vivo.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Protein phosphatases possibly involved in rat spermatogenesis.

The expression of mRNAs for catalytic subunits of serine/threonine protein phosphatases 1 (PP-1) and 2A (PP-2A) in various rat tissues were examined. Four kinds of probes were used to detect mRNAs for two isotypes of PP-1 (dis2m1 and dis2m2), and two isotypes of PP-2A (PP-2A alpha and PP-2A beta). mRNAs for all of these four catalytic subunits were expressed in almost all tissues at substantial levels. They were expressed in two different sizes in most tissues. Remarkable evidence is that the smaller sized mRNAs of dis2m1 and PP-2A beta, 1.8 kb and 1.4 kb in length, respectively, were specifically highly expressed in testis. Both these smaller sized mRNAs began to be expressed at the age when meiosis started and were detected in testicular germ cells at the pachytene stage of meiotic prophase. Protein phosphatases which have peptides encoded by dis2m1 and PP-2A beta as catalytic subunits may play important roles in spermatogenesis.

Animals↗
PubMed1990

Isolation of genes highly expressed in early and late stages of Friend virus-induced erythroleukemia in mice.

We isolated two genes that are highly expressed in Friend erythroleukemia. The first one, expressed at an extremely high level in a late-stage tumorigenic cell line F5-5, was found to be a species of intracisternal A-particle. Most of those genomes in F5-5 DNA were not amplified nor rearranged compared with those in the normal cell DNA, suggesting transcriptional activation. Another late-stage cell line T3K showed similar results. The second gene, highly expressed in early-stage cells but weaker in late-stage cells, was identified as one of the heme-synthesizing enzymes, uroporphyrinogen decarboxylase. Usefulness of these two genes for the analysis of erythroid transformation and differentiation will be discussed.

Animals↗
PubMed1990

Unusual hyperporphyrin spectrum by bis(glutathione dimethyl ester)-hemin complex, a model of cytochrome P-450-thiolate complexes.

A bis(thiolato) complex of iron-porphyrin exhibiting a "split Soret band" with peaks at 374 and 466 nm, classified as a "hyperporphyrin (HP) spectrum", was prepared with Fe(III)protoporphyrin dimethyl ester (FePPIXDME), glutathione dimethyl ester (GSHDME) and tetrabutylammonium hydroxide in acetone solvent. The structure of the complex was characterized by comparing their electronic absorption and electron spin resonance (ESR) spectra with those of thiolate adducts of cytochrome P-450 and their chemical model complexes. Under the same conditions as those for the formation of the HP spectrum, the generation of the free superoxide anions was detectable by ESR spectrometry at 77K. On the basis of the results, the possible reaction mechanism generating the superoxide anions by the bis(GSHDME)-FePPIXDME complex was proposed.

Animals↗
PubMed1990

Dose escalation trial of a novel calcium antagonist, AT877, in patients with aneurysmal subarachnoid haemorrhage.

The initial dose-escalating clinical trial of a novel calcium antagonist, AT877, in patients with aneurysmal subarachnoid haemorrhage is reported. AT877 is characterized by its strong spasmolytic activity, its inhibition of intracellular calcium ion activity, and the inhibition of several protein kinases. A total of 113 patients (Hunt and Hess grades I to IV) who had undergone surgery within 3 days of aneurysmal rupture entered the study. Patients were divided into 5 groups according to the total daily dose of AT877: I: 20 mg; II: 40 mg; III: 60 mg; IV: 90 mg; and V: 120-180 mg. AT877 was given by intravenous infusion over 30 min two or three times a day for 14 days after surgery. Although AT877 did not completely abolish angiographic vasospasm, severe vasospasm was seen less frequently in patients given higher doses. Vasospasm was the cause of a poor clinical outcome (Glasgow outcome scale rating 3 or greater) in 19%, 7%, 9%, 8%, and 6% of the patients in groups I to V, respectively. The results indicated a favourable clinical effect of AT877 at doses above 40 mg per day. Only mild hypotension was seen, even when 60 mg of AT877 was infused over 30 min. AT877 appears to be effective in patients with subarachnoid haemorrhage. Part of its effect may be attributable to protection of the brain from ischaemic insults due to chronic cerebral vasospasm. However, the drug still needs to be evaluated in a placebo-controlled double-blind trial (which is currently being carried out).

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