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Biomedical subjects

R Okuda

Publications and source records attributed to R Okuda.

At least 37 records · Page 2Linked to original sources
PubMed1985

Fluid-sorption phenomena in sterilized polyethylene acetabular prostheses.

The weight changes due to fluid-sorption were measured in 62 radiation-sterilized acetabular sockets and 10 unsterilized discs. The materials included two types of ultra-high molecular weight (UHMW) polyethylene (RCH 1000; Hi-Fax 1900) and a carbon-fibre-reinforced polyethylene (CFPE). The fluid absorption curve was consistently biphasic. In the first 30 d soak-period (Phase 1), the initial rate of fluid absorption averaged 153 micrograms/d for conventional UHMW polyethylene and 278 micrograms/d for carbon-fibre-reinforced polyethylene. In Phase 2, beyond 30 d and up to 400 d, fluid absorption reduced to linear rates of 27 micrograms/d for UHMW polyethylene and 43 micrograms/d for CFPE. The latter soak-weight-gain values corresponded to only 0.00016%/d and 0.00034%/d respectively. There was little difference in absorption rates between sterilized and unsterilized samples. However soak rates were generally higher in water compared to serum.

Absorption↗
PubMed1983

Anti-streptococcal cell membrane and anti-human glomerular basement membrane titers in sera of patients with poststreptococcal acute glomerulonephritis and anaphylactoid purpura.

To clarify the immunological mechanisms in poststreptococcal acute glomeulonephritis (PSAGN) and anaphylactoid purpura (AP), anti-streptococcal cell membrane (anti-SCM) and anti-human glomerular basement membrane (anti-GBM) titers in the sera of patients with PSAGN and AP were determined by passive hemagglutination with chromic chloride-treated sheep erythrocytes. Sodium lauryl sulfate (SLS) soluble SCM and collagenase soluble GBM were used as soluble antigens. Positive anti-SCM titers (greater than 1:8) were demonstrated in 10 of 14 patients (71.4%) with PSAGN and in 4 of 9 patients (44.4%) with AP with evidence of antecedent streptococcal infection. Two of 4 patients with AP without evidence of antecedent streptococcal infection had positive anti-SCM titers. No correlation was noted between anti-streptolysin O (ASO) titers and anti-SCM titers in patients with PSAGN or AP, but many patients with high ASO titers also had high anti-SCM titers. No positive anti-GBM reactions were detected in patients with PSAGN or AP. No cross-reactions were noted between SLS soluble SCM and collagenase soluble GBM.

Acute Disease↗
PubMed1980

Defective phagocytosis confined to Staphylococcus aureus in a female infant with recurrent infections.

Defective chemotaxis and phagocytosis of Staphylococcus aureus was identified in a female infant with marked hepatosplenomegaly and recurrent infections. Neutrophil mobilization from the marrow and marginal pool; random mobility; phagocytosis of yeast particles, latex beads and carbon particles; phagocytosis and intracellular killing capacity of Streptococcus pyogenes and E. coli; and NBT dye reduction were normal. Infiltration of neutrophils was depressed in the skin window test. The complement system and cellular immunity were intact. The patient also had a persistent EB virus infection. Defective phagocytosis limited to Staphylococcus aureus seems to be caused by an intrinsic cellular defect, such as congenital defect in neutrophil receptors for Staphylococcus aureus.

Bacterial Infections↗
PubMed1979

Bidirectional axonal transport of free glycine in identified neurons R3--R14 of Aplysia.

The axonal transport of 3H-amino acids was studied in the axons of identified neurons R3--R14 in the parietovisceral ganglion (PVG) of the mollusc Aplysia. The PVG was incubated (3--24 hr) in media containing physiological concentrations of single 3H-amino acids while the isolated nerve was superfused with plain or chemically altered media. The nerve was then sliced into sequential segments for biochemical analyses or fixed for autoradiography. 3H-glucine was transported at 70 mm/day in 6X greater quantities than other amino acids which were transported at less than 40 mm/day. In the 3H-glycine experiments, greater than 80% of the label transported into the nerve remained as free glycine, comigrating with glycine in thin-layer chromatographs. In autoradiographs of sections 4 mm from the ganglion-nerve barrier, greater than 50% of the silver grains were over R3--R14 axons which occupy less than 10% of the nerve cross-sectional area. EM autoradiographs confirmed that grains were within R3--R14 and not in surrounding glia. The selective transport of glycine was inhibited by Hg2+, by vinblastine and Nocodazole, and by low Ca2+ media. Autoradiographs of vinblastine-treated nerves showed a drastic reduction in label over R3--R14 and other axons. Label was also transported retrogradely; this transport rate was similar to the orthograde rate, but 5--10 times less label moved retrogradely. Autoradiographs showed that the retrograde label was localized to R3--R14 axons. This report clearly demonstrates the rapid, selective, and bidirectional transport of a free amino acid and provides further evidence that glycine may be used as a neurochemical messenter by neurons R3--R14.

Amino Acids↗
PubMed1979

Replica technique for scanning electron microscope examination of occlusal amalgam margins.

A new replicating technique, the modified adhesion relief method, was developed to investigate the marginal integrity of the occlusal surface of amalgam restorations over a period of years. The accuracy of the replicas was confirmed by scanning electron microscope comparison with the original teeth. The tooth to be studied need not be extracted. The technique makes it possible to continue the observation of restored teeth in the oral cavity for long periods. The technique does not require special equipment and is uncomplicated.

Cellulose↗
PubMed1979

Tuberous sclerosis: early neurologic manifestations and CT features in 18 patients.

Early clinical manifestations and radiologic features of tuberous sclerosis were studied in 18 consecutive patients encountered in the past two years, including two patients harboring an associated intraventricular tumor (giant-cell astrocytoma). Depigmented naevi rather than adenoma sebaceum, infantile spasms and intracranial calcifications were the cardinal early features in this present series, and CT scanning proved to be the single most useful diagnostic technique in the early detection of intracranial calcifications and therefore for the early diagnosis of this disorder. CT scanning was also useful in detecting the intraventricular tumors in the early stage before they became clinically manifest.

Adolescent↗
PubMed1979

Interaction among IgE-mediated hypersensitivity reaction, PCA reaction and delayed hypersensitivity reaction (at local skin sites of monkeys).

The effect of the IgE-mediated reaction on the passive cutaneous anaphylaxis (PCA) reaction was studied at local skin sites of monkeys, and we found that the IgE-mediated reaction appeared to enhance the PCA reaction. Interactions among IgE-mediated reaction, PCA reaction and delayed hypersensitivity reaction were also determined. Contact dermatitis induced with DNCB was utilized as the delayed hypersensitivity reaction. The IgE-mediated reactior or PCA reaction, as well as simple serum irritation, enhanced the delayed hypersensitivity reaction. It is thus assumed that the IgE-mediated reaction enhances the PCA reaction and that this in turn accelerates the delayed hypersensitivity reaction.

Animals↗
PubMed1979

Epidemiology of rheumatic fever in Japan.

The number of patients with the first attack of rheumatic fever reached a peak in 1960, decreased remarkably until 1968, then has remained unchanged for the last nine years. Approximately 10% of rheumatic patients still develop recurrences.

Child↗
PubMed1979

Rheumatic heart disease in childhood: comparative study between Japan and Thailand.

This report showed the comparative study of the rheumatic fever and rheumatic heart disease in Japan and Thailand. At first, there is remarkable difference about the incidence of the rheumatic heart disease. The incidence of the rheumatic heart disease in Thailand was one hundred times that in Japan. Secondly, there is particular difference about the course of mitral stenosis in childhood. In Japan common pattern of rheumatic heart disease was slight mitral insufficiency and mitral stenosis was seldom. In Thailand mitral stenosis was observed in 5% on rheumatic heart disease, and mitral stenosis developed early following an attack of rheumatic fever. These differences were supposed due to the socio-economic state in each country.

Adolescent↗