Search PubMed⌕ Search

Biomedical subjects

R Shiba

Publications and source records attributed to R Shiba.

At least 37 records · Page 2Linked to original sources
PubMed1996

Occipitoatlantal and occipitoaxial hypermobility in Down syndrome.

STUDY DESIGN: In this study, the authors evaluated upper cervical spine in 75 children and adolescents with Down syndrome on the basis of lateral flexion-extension radiographs. OBJECTIVE: To assess occipitoatlantal motion and occipitoaxial motion in children and adolescents with Down syndrome compared with age-matched control subjects. SUMMARY OF BACKGROUND DATA: Although previous studies have described a high prevalence of occipitoatlantal hypermobility in Down syndrome, there have been no comparisons with age-matched control subjects. Only a few reports have mentioned the physiologic relation between the occiput and axis other than basilar impression. Moreover, there have been no reports examining anteroposterior mobility in abnormal conditions. METHODS: Seventy-five children and adolescents with Down syndrome and 30 age-matched control subjects were examined. Lateral radiographs of the upper cervical spine in flexion and extension were taken, and anteroposterior translation of the occiput in relation to the atlas and axis was measured. RESULTS: Anteroposterior occipitoatlantal hypermobility was found to be present in children and adolescents with Down syndrome even when compared with age-matched control subjects. Occipitoaxial hypermobility was observed only when atlantoaxial instability was present. CONCLUSION: In evaluating the upper cervical spine in Down syndrome, it is necessary to pay attention to the relation between the occiput, atlas, and axis.

Adolescent↗
PubMed1995

A novel mutation substituting tryptophan with arginine in the carboxyl-terminal, non-collagenous domain of collagen X in a case of Schmid metaphyseal chondrodysplasia.

A novel nucleotide change in the collagen X gene was identified in a Japanese family with Schmid metaphyseal chondrodysplasia (SMCD). The T to C change at nucleotide 1951 resulted in replacement of tryptophan by arginine at residue 651 (W651R). This missense mutation is considered to be responsible for SMCD because 1, the same mutation was not be identified in the collagen X gene from normal individuals; 2, the mutation segregated with the SMCD phenotype in the index family; 3, the substituted amino acid is highly conserved in type X collagens, and 4, the mutation causes a marked change in the hydrophobicity profile of the surrounding region in the NC1 domain. This novel mutation (W651) seems to have the same impact on bone development as W651X mutation.

Amino Acid Sequence↗
PubMed1994

Activin A stimulates mitogenesis in Swiss 3T3 fibroblasts without activation of mitogen-activated protein kinases.

Activin A stimulated DNA synthesis and transient c-fos expression in quiescent Swiss 3T3 fibroblasts. The activin A-induced DNA synthesis was dose-dependent with a half-maximal effect obtained at 0.3 nM. The maximal response obtained at 10 nM was comparable with that induced by 5 ng/ml basic fibroblast growth factor. Swiss 3T3 fibroblasts expressed abundant high affinity binding sites for 125I-labeled activin A with a Kd value of 0.63 nM and the number of binding sites at 24,000/cell. Northern blot analysis revealed that Swiss 3T3 fibroblasts express a high level of type II activin receptor mRNA. In an attempt to elucidate the mechanism of mitogenic action of activin A, we examined the effect of activin A on mitogen-activated protein kinase activation. Unexpectedly, however, activin A did not induce kinase activation under conditions in which basic fibroblast growth factor and endothelin-1 at similar or even less potent mitogenic concentrations did. Furthermore, activin A did not induce phosphorylation of the Erk2 species of mitogen-activated protein kinase. These observations strongly suggest that the activation of mitogen-activated protein kinase is not a necessary step for activin A-induced DNA synthesis in Swiss 3T3 fibroblasts.

3T3 Cells↗
PubMed1994

Long-term serum/plasma-free culture of human cytotoxic T lymphocytes induced from peripheral blood mononuclear cells.

Tumor-specific human cytotoxic T lymphocytes (CTL) were induced by co-culturing peripheral blood mononuclear cells with X-ray-irradiated human lung squamous carcinoma cells, SQ-5, in the medium supplemented with interleukin(IL)-1, IL-2, IL-4 and IL-6, and 5% autologous plasma for 3 or 5 days. The CTL grew in serum/plasma-free medium containing these four interleukins and 0.5% bovine serum albumin for over a month and maintained killing activity of target cells within 48 h at an effector/target ratio of 1.25. Their growth was essentially dependent on the target SQ-5 cells, which were renewed every 5 days. Under these conditions, IL-4 and IL-6 could be omitted. When anti-CD3 monoclonal antibody was added to the serum/plasma-free medium supplemented with IL-1 and IL-2, the target tumor cells were not required to maintain the specific killing activity of the CTL. A large number of CTL (10(11)) were obtained in 35 days.

Carcinoma, Squamous Cell↗
PubMed1993

Cervical congenital kyphosis with atlantoaxial dislocation. A case report.

Congenital kyphosis and atlantoaxial dislocation in a 13-year-old boy was treated by a C1 laminectomy and C2-C5 laminoplasty with fusion from the occiput to C2. This resulted in postoperative neurologic deterioration, but a secondary anterior C3 vertebrectomy followed by a C2-C5 fusion helped restore neural function. In the presence of congenital cervical kyphosis, anterior rather than posterior decompression and fusion is recommended, particularly in the presence of a stenotic spinal canal.

Adolescent↗
PubMed1992

Cloning and expression of rat preproendothelin-3 cDNA.

We report here the cloning and expression of a rat full-length cDNA encoding preproendothelin-3 (preproET-3). The predicted rat preproET-3 consisted of 167 amino acid residues. As in other ET-family peptides, the mature rat ET-3 was predicted to be produced through unusual processing from a 41-residue intermediate, the big ET-3 in rat. Transient transfection of COS-7 cells with the cloned preproET-3 cDNA resulted in the production of mature ET-3 and this production was inhibited by phosphoramidon, a metaloprotease inhibitor. This suggested that a phosphoramidon sensitive mechanism was involved in the production of ET-3 in the transfected COS-7 cells. Northern blot analysis showed that an approximately 3.0-kb rat preproET-3 mRNA was expressed in rat tissues, including the eye ball, submandibular gland, brain, kidney, jejunum, stomach and spleen. A 2.0-kb and a 3.3-kb mRNA were also detected in the eye ball and small intestine, respectively. The distinct distribution of rat preproET-3 mRNA from that of preproET-1 mRNA suggested that ET-1 and ET-3 played different roles.

Amino Acid Sequence↗
PubMed1992

Radioprotective effect of exogenous glutathione on rat parotid glands.

The prophylactic effect of glutathione (GSH) on radiation injury in rat parotid glands was investigated. GSH was administered to male Wistar rats i.p. 15 min prior to irradiation. The necrosis index (NI) of the glands was determined histologically 24 h after a single dose of 15, 30, or 60 Gy. Total amylase activity, total protein content and wet weight of the glands were measured 30, 60 and 90 days after irradiation. Administration of GSH prior to radiation minimized acute and chronic radiation injuries as a function of the GSH dose: i.e. reduction of NI and prevention of the decrease in total amylase activity, total protein content and gland weight. The intraglandular level of non-protein-bound thiols (NPSH) and GSH increased significantly after i.p. administration of GSH, whether or not the glands were irradiated. An autoradiographic study revealed that i.p.-administered 35S-GSH was actively taken up by the glandular parenchyma, especially in the acini and ducts. It was shown that elevation of the intraglandular level of NPSH after exogenous administration of GSH protected the parotid glands from radiation injury in the rat.

Animals↗
PubMed1991

Characterization of the effect of endothelins in canine cerebral arteries.

In a few populations of endothelial cells of dog basilar arteries, endothelin (ET)-like immunoreactivity was detected to be present. ET-1, ET-2, and ET-3 caused vasoconstrictor responses but not vasodilator responses in isolated ring preparations of dog cerebral arteries in vitro. The ED50 values for the contractions were 411 pM, 478 pM, and 26.5 nM for ET-1, ET-2, and ET-3, respectively. NiCl2 (10(-3) M) attenuated the contractions induced by ET-3 (10(-8)-3 x 10(-7) M) and those to relatively low doses (10(-9) M) but not higher doses (10(-8)-10(-7) M) of ET-1 and ET-2. The contractions in response to ET-1, ET-2, and ET-3 were greatly attenuated in Ca(2+)-free solutions, although high concentrations of ET-1 and ET-2 still evoked contractions. These results suggest that the vasoconstriction induced by ET-3 and lower doses of ET-1 and ET-2 largely depends on the influx of Ca2+ ions. Furthermore, additional distinct mechanisms may contribute to the vasoconstrictor effects of high concentrations of ET-1 and ET-2. The presence of endothelin-like immunoreactivity in endothelial cells suggests that endothelin is a potential endogenous spasmogen.

Animals↗
PubMed1991

Possible role of endothelin in the pathogenesis of cerebral vasospasm.

Since the discovery of endothelin-1 (ET-1), its involvement in cerebral vasospasm after subarachnoid hemorrhage (SAH) has been suspected. We performed various experiments, first to demonstrate the presence of ET in both patients and dogs with SAH, and second to examine the effects of ET synthesis inhibition in experimental vasospasm. Here we report that ET was present in both plasma and cerebrospinal fluid (CSF) in SAH, but did not correlate with vasospasm. However, ET was locally expressed in the vascular endothelium in vasospasm. Several therapeutic approaches causing the inhibition of ET synthesis were effective in preventing the development of vasospasm. Such approaches utilized drugs that inhibited RNA and DNA synthesis. Among them, actinomycin D treatment was most effective. We also utilized phosphoramidon, a recently found conversion inhibitor of big ET to ET. However, this product failed to ameliorate the development of vasospasm. Therefore, although we cannot yet conclude that ET is the main cause of cerebral vasospasm, it may, at least, act as one of the modifying factors in cerebral vasospasm.

Animals↗
PubMed1991

An experimental study on transpedicular screw fixation in relation to osteoporosis of the lumbar spine.

In order to elucidate the relationship between the severity of osteoporosis and the fixation strength of a pedicle screw, screw pull-out tests were performed using cadaveric lumbar vertebrae. The severity of osteoporosis was evaluated by the Jikei osteoporosis grading scale (Jikei method), bone mineral density, and microdensitometry. When a 7.0-mm screw was used, the pull-out force of the screw was 1,056.4 N in the normal group (as determined by the Jikei method), while it was 495.6 N in the Grade I osteoporosis and 269.5 N in the Grade II osteoporosis groups, respectively. There were also positive correlations between the pull-out force and bone mineral density and each parameter of the microdensitometry method. When bone cement was used in an osteoporotic vertebra, twofold stronger pull-out force was obtained in comparison to that obtained without bone cement.

Aged↗
PubMed1991

Endothelins: vasoconstrictor effects and localization in canine cerebral arteries.

1. The vascular effects of endothelin and localization of endothelin-like immunoreactivity were characterized in isolated cerebral arteries of dogs. 2. Endothelin-like immunoreactivity was detected in a few populations of endothelial cells of dog basilar artery. 3. Endothelin-1, endothelin-2 and endothelin-3 contracted isolated ring preparations of cerebral arteries in a dose-dependent manner independently of the presence of endothelium. The ED50 values (and 95% confidence intervals) for the contraction were 411 pM (242-697 pM) and 478 pM (295-776 pM) for endothelin-1 and endothelin-2, respectively. Endothelin-3 induced vascular contraction at a higher concentration (ED50 = 26.5 nM, 95% confidence interval = 15.7-45.7 nM). 4. The increases in tone induced by endothelin-1 and endothelin-2 did not return to the resting level after repeated washings, while a rinse with Krebs solution reversed the vasoconstrictor response to endothelin-3. The endothelins did not cause any vasodilator response in arteries precontracted with uridine 5'-triphosphate even in the presence of intact endothelial cells. 5. NiCl2 (1 mM) attenuated the contractions induced by endothelin-3 (10-300 nM) and those to relatively low doses (1 nM) but not higher doses (10-100 nM) of endothelin-1 and endothelin-2. The contractions in response to endothelin-1, endothelin-2 and endothelin-3 were greatly attenuated in Ca(2+)-free solutions although high concentrations of endothelin-1 and endothelin-2 still evoked contractions. 6. These results suggest that the vasoconstriction induced by endothelin-3 and lower doses of endothelin-1 and endothelin-2, largely depends on the influx of Ca2+ ions. The apparent insensitivity to Ni2+ shows that additional distinct mechanisms also operate in the vasconstrictor responses to high concentrations of endothelin-1 and endothelin-2. 7. The presence of endothelin-like immunoreactivity in endothelial cells suggests that endothelin is a potential endogenous spasmogen.

Animals↗
PubMed1991

[Combined preoperative treatment with bilateral intra-arterial chemotherapy (CBDCA + PEP) and radiotherapy of oral cancer on the midline].

Intra-arterial chemotherapy from bilateral superficial temporal arteries and radiotherapy were carried out preoperatively on two patients with oral cancer on the midline. Total doses of preoperative chemo- and radio-therapies were 160 mg/m2 of carboplatin, 50 mg of peplomycin and 20 Gy of 60Co-irradiation, respectively. Therapeutic effect of preoperative chemo- and radio-therapies was evaluated on the resected materials from histological point of view. In case 1, the effect was judged as Grade II A in Oboshi's classification, which indicated a mild destruction of architecture of tumor tissue and a few viable tumor cells, but an extreme reduction of the primary lesion was observed on clinical appearance. In case 2, the therapeutic effect was regarded as Grade II B, which indicated a severe destruction of architecture of tumor tissue and few viable tumor cells. Concerning toxicity, mucositis and slight thrombocytopenia (96,000/mm3) in case 1, and mucositis and leukopenia (2,300/mm3) in case 2 appeared. However, they soon recovered after termination of the preoperative therapies. From the above results, it was considered that a combination of bilateral intra-arterial chemotherapy and radiotherapy was quite effective as a preoperative treatment for oral cancers on the midline at the same doses of anti-neoplastic agents and irradiation as for the other unilateral oral cancers.

Aged↗
PubMed1990

Involvement of endothelin in the regulation of human vascular tonus. Potent vasoconstrictor effect and existence in endothelial cells.

Endothelin, a recently discovered endothelium-derived peptide, has been reported to produce potent vasoconstriction in various vessels of experimental animals. To study the involvement of endothelin in the regulation of vascular tonus in humans, isolated human mesenteric arteries were investigated by both pharmacological and immunohistochemical methods. The vasoconstrictor action of endothelin-1 was examined on ring segments of human mesenteric arteries. Endothelin-1 induced a slowly developing and sustained contraction, with an EC50 value (half-maximal effective concentration) of 2.9 x 10(-9) M, two orders of magnitude smaller than that of norepinephrine (EC50 of 3.9 x 10(-7) M), indicating that the vasoconstrictor action of endothelin-1 is about 100 times more potent than that of norepinephrine. The contractile effect of endothelin-1 was affected neither by adrenergic, cholinergic, histaminergic, nor serotonergic antagonists, nor by inhibitors of arachidonic acid metabolism. The vasoconstrictor response to endothelin-1 was effectively antagonized by nicardipine, a dihydropyridine Ca2+ channel blocker. Endothelin-1 profoundly augmented contractile response to Ca2+ in partially depolarized tissues. Immunohistochemical studies revealed for the first time that endothelin-like immunoreactivity was localized in endothelial cells of human mesenteric artery. The results of the present study indicate that endothelin-1 is one of the most potent vasoconstrictors in the human mesenteric artery and that it induces vasoconstriction via an ultimately accelerating Ca2+ influx through voltage-dependent Ca2+ channels. Since endothelin-1 can be located in human endothelial cells, it may play an important physiological or pathophysiological role.

Adult↗
PubMed1989

Vasoconstrictor response of large cerebral arteries of cats to endothelin, an endothelium-derived vasoactive peptide.

Endothelin, a 21-amino acid peptide produced by vascular endothelial cells, caused a sustained constriction of isolated large cerebral arteries of cats in a dose-dependent manner. The increased tone of the tissue did not return to the resting level after repeated washings. No vasodilator response was evoked by endothelin in the presence of an active tone. The contractile response of cerebral arteries was not inhibited by rubbing of the endothelium, cold storage denervation or indomethacin. In contrast, nicardipine or diltiazem antagonized the endothelin-induced contraction non-competitively. No contraction was evoked by endothelin in a Ca2+-free solution while the addition of Ca2+ ions in the presence of endothelin in a Ca2+-free solution caused a sustained contraction. Ca2+-induced contraction in the Ca2+-free solution containing endothelin was also inhibited by nicardipine. Therefore, endothelin causes a direct contraction of the smooth muscles of cat cerebral arteries, probably by activating the influx of Ca2+ ions through L-type Ca2+ channels of smooth muscles.

Animals↗
PubMed1989

Elimination of intravenously injected endothelin-1 from the circulation of the rat.

The rate of elimination and the fate of endothelin-1 (ET-1) from the circulating blood was studied in urethane-anesthetized rats by intravenous injection of [125I]-labeled ET-1. The vasoconstrictor activities of the iodinated ET-1 were confirmed to be similar to those of native ET-1. Following i.v. bolus injection of 30 pmol/kg of [125I]-ET-1 into the femoral vein, the total radioactivity of the right atrial blood decayed rapidly, with a half-life of 7 min. At 5 min after the injection, the administered radioactivity distributed chiefly to the parenchyma of the lungs, kidneys, and liver. The analysis of the chemical form of labeled peptides from the plasma by reverse-phase high-performance liquid chromatography (HPLC) demonstrated no appreciable amount of degraded forms of [125I]-ET-1 in the blood for up to 60 min. [125I]-ET-1 was also stable for up to 60 min upon incubation in vitro with heparinized rat blood at 37 degrees C. Even when the same amount of labeled ET-1 was injected together with a pressor dose (1,500 pmol/kg) of cold ET-1, the half-life of the radioactivity in the bloodstream was exactly identical to that for [125I]-ET-1 alone. Nevertheless, the pressor response continued for more than 90 min after i.v. bolus injection of 1500 pmol/kg of ET-1 to the rat. These results clearly indicate that the elimination of ET-1 from circulating blood and the ET-1-induced pressor response are not in parallel, and the relatively rapid disappearance of ET-1 from the bloodstream is mostly due to the removal of the peptide by the parenchymal tissues, in the anesthetized rat. The long-lasting pressor action of ET-1 may be ascribed to our previous finding that the dissociation of ET-1 from its specific binding sites on vascular smooth muscle cells is extremely slow.

Animals↗