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Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 1,387 records · Page 77Linked to original sources
PubMedDate not supplied

Intracranial contour extraction with active contour models.

A novel image processing scheme for extracting the intracranial contours in axial magnetic resonance data sets is proposed. The scheme incorporates the method of active contour models, a recently introduced paradigm for contour extraction. Its performance is nearly ideal for T2-weighted images. Although the performances for proton-density-weighted images and T1-weighted images drop slightly, qualitatively satisfactory extraction still can be obtained for T1-weighted images. Due to high degree of automation, the scheme should help speed up some image processing applications that require the presegmentation of the intracranial cavity.

Artifacts↗
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Cooperativity and intermediate structures of single-stranded DNA binding-assisted RecA-single-stranded DNA complex formation studied by atomic force microscopy.

The formation of a complex between RecA protein and single-stranded (ss) DNA was studied systematically by atomic force microscopy (AFM) by varying incubation time and the molecular ratio of RecA protein to single-stranded DNA binding (SSB) protein. New intermediate structures, such as small circular, tangled, and protruded structures in the absence of SSB and sharply turned structures in the presence of SSB, were clearly identified at the early stage of complex formation. These structures have probably resulted from competitive binding of RecA and SSB to DNA. After long incubation, only fully covered RecA-ssDNA and totally RecA-free SSB-ssDNA complexes were present regardless of RecA concentrations. Together with intermediate structures which consisted of only two parts, that is, ssDNA covered by SSB and by RecA proteins, the observation suggested strong neighbor cooperative binding of RecA to ssDNA assisted by SSB.

Allosteric Regulation↗
PubMedDate not supplied

Quantitative determination of urinary protein components of children with postural proteinuria.

Twenty-one protein components were measured in urine specimens from 12 subjects with postural proteinuria in the recumbent posture and after a period of upright lordotic posture. The lordotic posture produced an increased urinary excretion of total protein and 19 protein components, particularly of albumin, IgG globulin, and transferrin (128, 68, and 167-fold, respectively). However, 90 min after the lordotic posture, most of the protein components returned to initial values, whereas albumin, IgG globulin, and transferrin remained high. beta 2-Microglobulin, retinol binding protein, and lysozyme showed the smallest increases after the lordotic posture. These findings suggest that proteinuria occurring after the lordotic posture may be characterized by an increased glomerular permeability.

Adolescent↗
PubMedDate not supplied

Successful thrombolytic therapy using tissue-type plasminogen activator in Kawasaki disease.

Thrombolytic therapy using tissue-type plasminogen activator was performed in a 7-month-old boy with massive mural thrombi in large coronary aneurysms due to Kawasaki disease. Magnetic resonance imaging successfully demonstrated mural thrombi in both proximal and distal coronary aneurysms and their disappearance after thrombolytic therapy. We conclude that for preventing acute myocardial infarction and sudden death intravenous and intracoronary thrombolytic therapy with tissue-type plasminogen activator may help in infants and children with Kawasaki disease who have thrombi in coronary aneurysms.

Coronary Aneurysm↗
PubMedDate not supplied

Aneurysmal change of the ductus arteriosus after prostaglandin E1 administration for pulmonary atresia: demonstration with magnetic resonance imaging.

We report a case of pulmonary atresia in which the ductus arteriosus underwent aneurysmal dilatation after infusion of prostaglandin E1 incorporated in lipid microspheres. To our knowledge this is the first case in which this rare morphological change has been demonstrated with the noninvasive method of magnetic resonance imaging.

Alprostadil↗
PubMedDate not supplied

Acute febrile mucocutaneous lymph node syndrome with multiple aneurysms: report of a case.

A 4-month-old male infant with acute febrile mucocutaneous lymph-node syndrome developed mitral regurgitation, pericardial effusion and multiple pulsating masses in the upper and lower extremities. Two-dimensional echocardiography demonstrated aneurysms in both coronary arteries. Arteriography of the right arm demonstrated multiple aneurysms. Seventeen months later, arteriography and two-dimensional echocardiography demonstrated regression of the aneurysms. This case provides evidence that regression of aneurysms can occur in mucocutaneous lymph node syndrome.

Acute Disease↗
PubMedDate not supplied

A bilayer "artificial skin" capable of sustained release of an antibiotic.

The most frequent complication of the bilayer "artificial skin", composed of a silicone sheet and collagen sponge described in a previous paper, was infection beneath it. This paper describes a new type of "artificial skin" in which microspheres containing antibiotics were installed beneath the silicone sheet, allowing a continuous release of antibiotics.

Adult↗
PubMedDate not supplied

Production of interleukin-6 by normal human trophoblast.

The placenta plays a number of important roles during pregnancy, some of which might be mediated by cytokines with multiple activities such as IL-6. Using an IL-6-dependent cell line, MH6o.BSF2, we showed that the placenta released IL-6 into the culture supernatant. Analysis of single-cell suspensions of placental cells determined the major source of IL-6 to be trophoblast. Using a mouse monoclonal antibody specific for IL-6 (alpha BSF2-I66), immuno-histochemical analysis of placental specimens demonstrated the localization of IL-6 only in the trophoblast layer. Additional immunocytochemical studies with single-cell suspensions of trophoblasts demonstrated the preferential presence of IL-6 molecules in syncytiotrophoblasts rather than cytotrophoblasts. The evidence that a high titer of IL-6 is produced spontaneously by syncytiotrophoblasts indicates that IL-6 may play immunological roles in fetomaternal interactions by means of IL-6-driven multiple immunoregulatory activities.

Cells, Cultured↗
PubMedDate not supplied

Fluorescence imaging with a laser trapping scanning near-field optical microscope.

We investigated fluorescence imaging using a near-field scanning optical microscope which uses a laser-stabilized gold nanoparticle as a near-field probe. This microscope is suitable for observations of biological specimens in aqueous solutions because the probe particle is held by a noncontact force exerted by a laser beam. Theoretical calculations based on Mie scattering theory are presented to evaluate the near-field enhancement by a gold particle of 40 nm diameter. We also present fluorescence images of a single fluorescent bead and discuss the near-field contribution to the fluorescence image in this type of microscope.

Journal Article↗
PubMedDate not supplied

Experimental studies on an artificial esophagus for the purpose of neoesophageal epithelization using a collagen-coated silicone tube.

An artificial esophagus was fabricated from a collagen-coated silicone tube 5 cm long, with an inner diameter of 2.5 cm and a wall thickness of 1 mm. The outer surface was coated with dry collagen to 5 mm thickness. The bilayered prosthesis was anastomosed to the cervical esophagus of adult mongrel dogs that were fed only by intravenous hyperalimentation (IVH) with 80 cal/kg/day and 60 ml water/kg/day for 3 weeks after the operation. Once the dogs began to consume food orally, the artificial esophagus dropped spontaneously into the stomach and formation of the neoesophagus was complete. Macroscopically, the neoesophagus showed no evidence of leakage or inflammation and had a smooth internal surface, but it developed slight segmental narrowing. Microscopically, layers of stratified squamous epithelium covered the neoesophagus within 3 to 4 weeks. The most characteristic feature of the artificial esophagus was that the replacement prosthesis did not remain in the esophagus after healing. Esophageal epithelization extended into the collagen layer coating the silicone tube and a new esophageal lumen was regenerated, thereby decreasing the chance of infection and leakage. However, neoesophageal stenosis was observed when the silicone tube was removed.

Animals↗
PubMedDate not supplied

Experimental studies on an artificial trachea of collagen-coated poly(L-lactic acid) mesh or unwoven cloth combined with a periosteal graft.

Artificial tracheas were fabricated from poly(L-lactic acid) mesh or unwoven cloth coated with collagen in order to reconstruct the respiratory airway by self regeneration without retaining the prosthesis at the replacement site, thus preventing infection, air leakage, granulation tissue formation, and displacement of the prosthesis. Nine weeks after placing a periosteal autologous graft from the tibia around the cervical trachea of a rabbit, bone rings formed without infection. Two weeks after replacement of an 8 X 8 mm window-shaped section of the cervical trachea with autologous periosteum, the internal surface of the trachea was well epithelialized without local complications, but ossification was not seen. One week after cervical substitution with our 2 cm long artificial trachea combined with the periosteal graft, cartilage was produced around the mesh material but neither ossification nor epithelization was observed thereafter, probably due to local infection. On the other hand, cartilage, bone, and epithelium did not form around the unwoven cloth artificial trachea after the substitution, probably because of severe infection due to collapse of the tracheal lumen. However, the formation of bone rings around the trachea suggests preservation of the neotracheal lumen, which may have potential for the treatment of tracheomalacia and/or bronchomalacia.

Animals↗
PubMedDate not supplied

BOLD contrast on a 3 T magnet: detectability of the motor areas.

To predict the potential and the limitations of functional MRI (fMRI) with a very high field magnet, the detectability and reproducibility of activation were evaluated by comparing the activation induced by a sequential finger movement task at 1.5 T with that at 3 T. The detectability of the premotor area, supplementary motor area (SMA), and ipsilateral sensorimotor area (SM1) showed significant improvement at 3 T. On the other hand, the detectability of contralateral SM1 was not significantly different between 1.5 and 3 T. The degree of activation was proportional to task demand in the ipsilateral SM1 and SMA, whereas that in the contralateral SM1 and SMA was not. FMRI with a 3 T magnet has greater potential for detection of neuronal activation as a functional network. These observations indicated that task demand and static magnetic field strength should be considered in interpretation of fMRI data for clinical usage.

Adult↗
PubMedDate not supplied

Membranous glomerulonephritis with nephrotic syndrome associated with chronic lymphocytic leukemia.

A 66-year-old woman was admitted to our hospital for evaluation of edema of the extremities. Laboratory findings suggested that she had nephrotic syndrome and chronic lymphocytic leukemia (CLL). Renal biopsy (with PAM staining) showed a spike formation in the capillary wall. Immunofluorescent staining revealed deposition of immunoglobulin G (IgG) and the third component of complement in the glomerular basement membrane. Electron microscopy showed fibrillary deposits in the subepithelium. These findings indicated membranous glomerulonephritis (MGN). In addition, focal segmental sclerosis and interstitial lymphocytic infiltration were observed in the renal biopsy specimen. In CLL patients nephrotic syndrome occurs rarely. Even if the complication occurs, MGN is not frequent. Both diseases are suspected to occur in association with each other, and immunologic abnormality contributes to their coexistence. Although administration of prednisolone and endoxan improved leukocytosis, proteinuria was not sufficiently improved with combination therapy.

Aged↗
PubMedDate not supplied

c-kit mutation in a population of patients with mastocytosis.

The c-kit Asp816Val activating mutation is found in all patients with mastocytosis with an associated hematologic disorder, and at least in a subset of patients with indolent mastocytosis. The case of an 11-month-old child is presented who was categorized as having indolent mastocytosis, and where the Asp816Val mutation was identified in lesional skin, but not in bone marrow or in peripheral blood mononuclear cell populations. The significance of these findings is discussed.

Humans↗
PubMedDate not supplied

Drug permeability of the endolymphatic sac.

Intravenously injected kanamycin sulfate (KM) was located in the endolymphatic sac (ES) of guinea pigs by an immunohistologic method. Kanamycin sulfate had passed through the capillaries in the subepithelial layer and reached the epithelial layer as early as 1 minute after injection. The amount of KM in the epithelial layer gradually increased with time (until 30 minutes after injection). The KM also accumulated in floating cells in the ES. These results tend to indicate that the ES is rather easily permeable to systemically administered drugs, which readily get into the regional endolymph. In conclusion, much more attention should be paid to the ES and drug ototoxicity associated with drug therapy in the management of patients with inner ear disturbances.

Aminoglycosides↗
PubMedDate not supplied

Cerivastatin induces carotid artery plaque stabilization independently of cholesterol lowering in patients with hypercholesterolaemia.

To prevent cardiovascular events in hyperlipidaemic patients, plaque stabilization by inhibition of localized inflammatory reactions in the blood vessels is important in addition to cholesterol lowering. Cerivastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor (statin), has more potent enzyme-inhibitory effects than other statins and has also been reported in vitro to inhibit, at low concentrations, various inflammatory reactions due to plaque instability. Cerivastatin was therefore administered over 12 months to five patients with hypercholesterolaemia and atherosclerotic plaque diagnosed by ultrasonography of the carotid artery, and changes in the plaque composition were determined. The mean cholesterol level decreased over the study period, although not significantly. However, the mean percentage of fibrous matrix of the plaque increased significantly from a mean of 11.2 +/- 7.7% at study entry to 18.3 +/- 5.9% at the end of the study. Additionally, the mean maximum plaque height was significantly reduced from 3.7 +/- 0.9 mm to 3.0 +/- 0.7 mm. These results indicate that cerivastatin induces plaque stability independently of cholesterol lowering.

Aged↗