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Biomedical subjects

S Ojima

Publications and source records attributed to S Ojima.

12 recordsLinked to original sources
PubMed2005

Stereochemistry of 1,2-dichloroethane adsorbed on Pt(111).

The rotational isomerism of 1,2-dichloroethane (DCE, CH2ClCH2Cl) adsorbed on Pt(111) was studied in the temperature range of 35-100 K using high-resolution electron energy loss spectroscopy and metastable atom electron spectroscopy. In the coverage below monolayer the physisorbed and chemisorbed species coexist at 35 K in the gauche and slightly distorted trans form, respectively. Owing to the direct Pt-Cl interactions, the nonbonding Cl 3p states of the chemisorbed DCE are split off, giving rise to degradation in symmetry from the pure trans form (C2h). The physisorbed gauche conformers are arranged with the C2 axis parallel (or heavily tilted) to the substrate and converted irreversibly to the pseudo-trans form by heating at 70 K. In the multilayer, the trans and gauche conformers exist at 35 K, where the former population is increased with increasing layer thickness. Upon annealing the bilayer at 80 K, the irreversible conversion takes place to yield a higher population of the gauche conformer in the topmost layer. The conformational stabilities and mutual changes of DCE adsorbed on a metal surface are discussed in terms of intramolecular rotational potential.

Journal Article↗
PubMed1992

Evaluation of a high-velocity flame-spraying technique for hydroxyapatite.

Titanium alloy sprayed with hydroxyapatite (HA) was developed by a high-velocity flame-spraying technique (HVFST). Biocompatible responses of bony tissues to high-velocity flame-sprayed HA (HVFS-HA) implanted into tibias of adult male rabbits was investigated 4 and 18 months after implantation by light and electron microscopy. Both light and electron microscope features in histological sections showed that inflammatory responses of tissues in situ were completely cleared and the interface between the bone and the implant was filled with newly formed bony substrate. This suggests that the HVFS-HA was sufficiently biocompatible to be adapted to the bone in situ.

Alloys↗
PubMed1987

Thoracic myelopathy secondary to ossification of the spinal ligament.

The authors describe their experience with 26 cases of thoracic myelopathy secondary to hypertrophic ossification of the spinal ligament (posterior longitudinal ligament and/or ligamentum flavum). The clinical manifestations of this condition and results of its surgical treatment are described. The commonest symptoms were numbness or tingling in the legs and feet and gait disturbance. Most of the patients with involvement of the upper thoracic spine showed typical features of thoracic myelopathy: that is, sensory and motor deficits in both the trunk and lower extremities, sphincter disturbance, and exaggerated tendon reflexes. Several patients with involvement of the thoracolumbar junction presented with atypical symptoms of thoracic myelopathy and were sometimes misdiagnosed and treated inappropriately. Surgical treatment, particularly laminectomy, was not always successful. Inconsistencies in the surgical outcome were caused by either operative complications or reversal of the initial improvement during the follow-up period. The results of anterior surgery for the condition were more favorable; however, use of this procedure was rarely indicated.

Adult↗
PubMed1979

Transforming DNA sequences in rat cells transformed by DNA fragments of highly oncogenic human adenovirus type 12.

Rat cell lines tranformed by viral DNA fragments, EcoRI-C and HindIII-G, of adenovirus type 12 DNA were analyzed for the viral transforming DNA sequences present in cell DNAs. Cell lines transformed by the EcoRI-C fragment of adenovirus type 12 DNA (leftmost 16.5% of the viral genome) contain most of the HindIII-G sequences of the HindIII-G fragment, but at a different frequency depending on the portions of the fragment. The sequence of the AccI-H fragment of adenovirus type 12 DNA (the left part of the HindIII-G; leftmost 4.5% of the viral genome) was detected dominantly in cells transformed by the HindIII-G fragment Southern blot analysis showed that viral DNA sequences are present at multiple integration sites in high-molecular-weight cell DNA from cells transformed by the EcoRI-C or HindIII-G fragment of adenovirus type 12 DNA. These results suggest that most of the HindIII-G sequences in cells transformed by the HindIII-G fragment are present as fragmented forms.

Adenoviruses, Human↗
PubMed1978

Detection and quantitation of adenovirus type 12 transforming DNA segments and their application in etiological studies of human neoplasia.

The oncogenic capacity of the tumour virus lies in a small region of the viral genome, and tumour cells and cells transformed by DNA tumour viruses often contain only a part of the viral genome, the portion including the transforming gene(s). The detection and quantitation of these gene(s) in tumour cell DNA can provide evidence for or against a possible etiological role of the virus in human neoplasia. In this communication, the isolation, purification and identification of the transforming segment of Ad 12 are described.

Adenoviridae↗
PubMed1977

Thioltrypsin. Chemical transformation of the active-site serine residue of Streptomyces griseus trypsin to a cysteine residue.

The active-site serine residue of Streptomyces griseus trypsin was converted to a cysteine residue, and the product, thioltrypsin, was purified through two chromatographic steps with organomercurial-Sepharose and soybean trypsin inhibitor-Sepharose as specific adsorbents. The purified preparation of thioltrypsin was found to contain a single residue of cysteine and to react with almost equimolar amounts of normality titrants. It exhibited only traces of catalytic activity toward typical trypsin substrates such as Nalpha-tosyl-L-arginine methyl ester, whereas it retained some activity toward "active ester" substrates such as Nalpha-carbobenzoxy-L-lysine p-nitrophenyl ester. The activity was inhibited by sulfhydryl-blocking reagents, but no inhibition was observed by reagents reactive with the active hydroxyl group of serine proteases. Leupeptin, a natural trypsin inhibitor of peptidyl nature, also inhibited thioltrypsin. Some difference in the mode of leupeptin inhibition, however, was detected between trypsin and thioltrypsin. The bindings of small synthetic ligands and soybean trypsin inhibitor to thioltrypsin were compared with those to trypsin.

Binding Sites↗