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T Okada

Publications and source records attributed to T Okada.

At least 253 records · Page 14Linked to original sources
PubMed1999

Evaluation of sleep apnea syndrome with low-field magnetic resonance fluoroscopy.

The aim of this study was to assess the upper airway status of sleep apnea syndrome (SAS) patients with low-field MR fluoroscopy. Twenty patients with clinically diagnosed SAS underwent upper airway monitoring using MR fluoroscopy for 5 min while awake and for 30 min while asleep. A 0.064-T permanent-magnet MR imaging system was used for the study. No patients required any sedative drugs because of the very small gradient noise, except in one case. No occlusion was observed while patients were awake. Nine patients showed repeated occlusion at retropalatal (Rp) pharynx, whereas 11 demonstrated both simple Rp occlusion and combined retropalato-retroglossal (Rp + Rg) occlusions (complex occlusion). The mean frequency of occlusion in complex cases was significantly higher than that in simple Rp cases (p < 0.05). Low-field MR fluoroscopy was useful in determining the occlusion level while asleep in patients with SAS because of its quiet gantry and long-term monitoring capability. The MR fluoroscopy technique should prove to be a valuable clinical tool for the diagnosis and for determining the appropriate therapy in patients with SAS.

Adult↗
PubMed1999

Dynamics of rat liver ecto-ATPase during development suggests its involvement in bile acid efflux. A cytochemical view.

We studied cytochemical localization of ectoadenosine triphosphatase in the rat liver during development from 15-day-old fetus to 4-week-old and adult animal. First signs of the enzyme activity were found in some of the primitive bile canaliculi of 15-day-old fetuses. The majority of canaliculi, however, did not reveal any reaction product. Although intensity of the cytochemical reaction increased at 20 days of gestation, it still remained relatively low. Intensity of the reaction increased significantly and its product became readily detectable in the liver of newborn rats. Liver of 1-, 2-, and 4-week-old animals showed strong reaction for ecto-ATPase at the luminal surface of the plasma membrane of the bile canaliculi. Liver of adult rats contained a prominent reaction product similar to that seen in newborns, 1-, 2-, and 4-week-old animals. At all stages of fetal development, as well as in postnatal and adult rats, reaction was found only within the hepatic bile canalicular system and exclusively at the luminal surface of the canalicular plasma membrane. Using diethyl pyrocarbonate (DEPC), a specific inhibitor of ecto-ATPase activity, cytochemical reaction was blocked in all examined samples. Results of the present study, taken together with established biochemical and immunological data, provide conclusive morphological evidence in support of the view that canalicular ecto-ATPase is involved in bile acid efflux.

Adenosine Triphosphatases↗
PubMed1999

Ecto-ATPase activity in the rat cardiac muscle: biochemical characteristics and histocytochemical localization.

We used a combined biochemical and histocytochemical approach to study ecto-ATPase in the rat cardiac muscle. The reaction medium employed for histocytochemical detection was optimized in biochemical assays to achieve the highest enzyme activity and lowest inhibition by the capture agent used for visualization of the reaction product. Approximately 70% of the enzyme activity was retained in samples after the fixation procedure. Divalent cations stimulated ecto-ATPase. High activity was detectable within a wide pH range. Histocytochemical reaction was observed at sites at which extracellular ATP can potentially exert its actions on the cardiac muscle: nerve endings, plasma membranes of cardiac myocytes and capillary endothelial cells, and T-tubules. Product of the reaction was found exclusively at the outer surface of the cells. In controls, enzyme activity was abolished by diethyl pyrocarbonate and slightly stimulated by digitonin and concanavalin A, whereas sodium orthovanadate, N-ethylmaleimide, and sodium azide yielded no effect. Our results support the view that cardiac ecto-ATPase is involved in important physiological functions and suggest that its activity may be regulated by the release of ATP from nerve endings.

Adenosine Triphosphatases↗
PubMed1999

Synthesis of a novel lipopeptide with alpha-melanocyte-stimulating hormone peptide ligand and its effect on liposome stability.

Introduction of liposomes into target cells is important for drug delivery systems. For this purpose, the surface of the liposome is equipped with ligand peptides, which may bind to specific receptors on the cell membrane. An artificial novel lipopeptide (MSH-C4A2) containing the alpha-melanocyte-stimulating hormone (alpha-MSH) sequence and two long alkyl chains was designed and synthesized, and the liposome, composed of egg phosphatidylcholine (EPC) and MSH-C4A2, was prepared. The stability of the liposome was estimated by measuring calcein leakage from the liposome inner phase. The stability of the liposome decreased upon addition of MSH-A4C2, which seemed to be attributable to the amphiphilic property of the peptide moiety (alpha-MSH) of MSH-A2C4. The stability was, however, recovered fairly well upon addition of cholesterol (Ch) or phosphatidylglycerol (PG). It was concluded therefore that the ternary system, MSH-C4A2/Ch/EPC or MSH-C4A2/PG/EPC, is suitable for preparing the functional liposome.

Cholesterol↗
PubMed1999

Synergistic activation of a family of phosphoinositide 3-kinase via G-protein coupled and tyrosine kinase-related receptors.

Phosphoinositide 3-kinase (PI 3-kinase) is a key signaling enzyme implicated in a variety of receptor-stimulated cell responses. Stimulation of receptors possessing (or coupling to) protein-tyrosine kinase activates heterodimeric PI 3-kinases, which consist of an 85-kDa regulatory subunit (p85) containing Src-homology 2 (SH2) domains and a 110-kDa catalytic subunit (p110 alpha or p110 beta). Thus, this form of PI 3-kinases could be activated in vitro by a phosphotyrosyl peptide containing a YMXM motif that binds to the SH2 domains of p85. Receptors coupling to alpha beta gamma-trimeric G proteins also stimulate the lipid kinase activity of a novel p110 gamma isoform, which is not associated with p85, and thereby is not activated by tyrosine kinase receptors. The activation of p110 gamma PI 3-kinase appears to be mediated through the beta gamma subunits of the G protein (G beta gamma). In addition, rat liver heterodimeric PI 3-kinases containing the p110 beta catalytic subunit are synergistically activated by the phosphotyrosyl peptide plus G beta gamma. Such enzymatic properties were also observed with a recombinant p110 beta/p85 alpha expressed in COS-7 cells. In contrast, another heterodimeric PI 3-kinase consisting of p110 alpha and p85 in the same rat liver, together with a recombinant p110 alpha/p85 alpha, was not activated by G beta gamma, though their activities were stimulated by the phosphotyrosyl peptide. Synergistic activation of PI 3-kinase by the stimulation of the two major receptor types was indeed observed in intact cells, such as chemotactic peptide (N-formyl-Met-Leu-Phe) plus insulin (or Fc gamma II) receptors in differentiated THP-1 and CHO cells and adenosine (A1) plus insulin receptors in rat adipocytes. Thus, PI 3-kinase isoforms consisting of p110 beta catalytic and SH2-containing (p85 or its related) regulatory subunits appeared to function as a 'cross-talk' enzyme between the two signal transduction pathways mediated through tyrosine kinase and G protein-coupled receptors.

Amino Acid Sequence↗
PubMed1999

Complexed prostate-specific antigen and its volume indexes in the detection of prostate cancer.

OBJECTIVES: To evaluate complexed prostate-specific antigen (cPSA), cPSA density (cPSAD), and cPSA adjusted for the transition zone volume (cPSA-TZ) in comparison with the free-to-total PSA ratio (F/T PSA) and free-to-complexed PSA ratio (F/C PSA) as a means of diagnosing prostate cancer. METHODS: Transition zone volume was determined in 137 of 142 men who underwent systematic sextant biopsies and had total PSA (tPSA) values between 4.1 and 10.0 ng/mL. cPSAD and cPSA-TZ were calculated by dividing the cPSA value by the whole prostate volume and the transition zone volume, respectively. RESULTS: Of the 137 men, 23 (16.8%) had prostate cancer. cPSA predicted the biopsy outcome better than tPSA, F/T PSA, or F/C PSA, although the difference was not significant. A cutoff value of 4.1 ng/mL for cPSA provided a specificity of 42% and a sensitivity of 87%. A combination of cPSA and F/C PSA maintained a sensitivity of 83% and gave an increased specificity of 54%. In a subgroup of 65 patients with smaller prostate volumes (less than 45 mL), the diagnostic value of cPSA-TZ was remarkably increased. A cutoff value of 0.31 for cPSA-TZ provided a sensitivity of 93% and a high specificity of 72%. CONCLUSIONS: cPSA was more specific than tPSA and F/T PSA. As a component of F/C PSA, free PSA could provide additional value to cPSA. cPSA-TZ and cPSAD could be better indicators for prostate cancer than cPSA.

Aged↗
PubMed1999

1,3-Disubstituted benzazepines as neuropeptide Y Y1 receptor antagonists.

A novel class of potent and selective non-peptide neuropeptide Y (NPY) Y1 receptor antagonists, having benzazepine nuclei, have been designed, synthesized, and evaluated for activity. Through a blind screening we found the compound 1-N-(3-(N'-(tert-butoxycarbonyl)amino)benzyl)-7-methoxy-(3-(3)-methyl ureido)-2,3,4,5-tetrahydro-1H-1-benzazepin-2-one (9: IC50 = 1.6 microM). Chemical modifications of 9 gave a potent NPY Y1 antagonist 3-(N-(4-hydroxyphenyl)-N'-methylguanidino)-1-N-(3-(N'-(tert-butoxy carbonyl)amino)benzyl)-2,3,4,5-tetrahydro-1H-1-benzazepin-2-one (14c: IC5(0=43 nM), which had no affinity for NPY Y2 and Y5 receptors.

Benzazepines↗
PubMed1999

Detection of ecto-ATPase activity in synaptic plasma membranes for studying extracellular ATP-induced signal transduction.

This paper describes protocol for the correlated light and electron microscopical histochemical visualization of the reaction product of ecto-ATPase activity in brain. The protocol employs a biochemically optimized incubation medium to adjust the appropriate kinetical parameters for detection of the histochemical reaction product by means of confocal laser scanning and electron microscopy. The reaction product is formed when the liberated inorganic phosphate is captured in histochemical reaction by the cerium ions. Confocal microscopy is performed in reflectance mode due to sufficient reflectance properties of the cerium-containing reaction product. Using this procedure, the prominent reaction of ecto-ATPase activity is readily detectable in hippocampus and cerebellum at sites where ATP is supposed to act as a synaptic neurotransmitter: on synapses of neurons in the pyramidal cell layer of hippocampus, in the granule cell layer of the dentate gyrus, and around synapse-containing areas in the granule cell layer of cerebellum. Reaction product is seen in close association with both pre- and postsynaptic membranes and exclusively extracellularly. Specificity of the visualization is justified in control experiments with diethyl pyrocarbonate, specific inhibitor of ecto-ATPase. The procedure is easy to perform, sensitive, and reproducible. It is recommended as a valuable tool in the arsenal of biochemical, immunochemical, and physiological techniques in studying signal transduction induced by extracellular ATP.

Adenosine Triphosphatases↗
PubMed1999

Significance of VLA-4-VCAM-1 interaction and CD44 for transendothelial invasion in a bone marrow metastatic myeloma model.

In previous work, we established the B9/BM1 syngeneic murine bone marrow metastasis model. Interleukin (IL)-6-dependent. IL-1-producing B9/BM1 cells, which colonize the vertebral and femoral marrow after i.v. injection, show great similarity in cell surface phenotype to human myeloma cells, especially the expression of 3 adhesion molecules, CD44, VLA-4 and ICAM-1. Here we investigated the function of these adhesion molecules by binding and transendothelial invasion assays using a newly established bone marrow-derived endothelial cell line (BMEC). A combination of monoclonal antibodies against CD44 and VLA-4 significantly inhibited the adherence of B9/BM1 cells to BMEC and anti-CD44 mAb especially blocked B9/BM1 transendothelial invasion of unstimulated BMEC cells. Results of additional experiments, in which the cells were treated with anti-CD44 and hyaluronidase, demonstrated that the interaction of CD44 molecules on B9/BM1 cells with hyaluronan on BMEC cells was a critical factor in both adhesion and transendothelial invasion in this model. However, stimulation of BMEC with TNFalpha resulted in increased invasion by B9/BM1 cells, which was completely suppressed by anti-VCAM-1 mAb, implicating a significant role of this adhesion molecule in this process during inflammation.

Animals↗
PubMed1999

Modulation of ET-1-induced contraction of human bronchi by airway epithelium-dependent nitric oxide release via ET(A) receptor activation.

1. The purpose of this work was to investigate whether endothelin-1 (ET-1) was able to induce the release of an inhibitory factor from the airway epithelium in isolated human bronchi and to identify this mediator as well as the endothelin receptor involved in this phenomenon. 2. In intact bronchi, ET-1 induced a concentration-dependent contraction (-logEC50 = 7.92+/-0.09, n = 18) which was potentiated by epithelium removal (-logEC50 = 8.65+/-0.11, n = 17). BQ-123 , an ET(A) receptor antagonist, induced a significant leftward shift of the ET-1 concentration-response curve (CRC). This leftward shift was abolished after epithelium removal. 3. L-NAME (3 x 10(-3) M), an inhibitor of nitric oxide (NO) synthase, induced a significant leftward shift of the ET-1 CRC, and abolished the potentiation by BQ-123 (10(-8) M) of ET-1-induced contraction. 4. In intact preparations, the ET(B) receptor antagonist BQ-788 induced only at 10(-5) M a slight rightward shift of the ET-1 CRC. In contrast, in epithelium-denuded bronchi or in intact preparations in the presence of L-NAME, BQ-788 displayed a non-competitive antagonism toward ET-1-induced contraction. 5. IRL 1620, a selective ET(B) receptor agonist, induced a contraction of the isolated bronchus (-logEC50=7.94+/-0.11, n= 19). This effect was not modified by epithelium removal or by BQ-123. BQ-788 exerted a competitive antagonism against IRL 1620 which was similar in the presence or absence of epithelium. 6. These results show that ET-1 exerts two opposite effects on the human airway smooth muscle. One is contractile via ETB-receptor activation, the other is inhibitory and responsible of NO release which counteracts via ETA-receptor activation the contraction.

Antihypertensive Agents↗
PubMed1999

Restoration of adrenal steroidogenesis by adenovirus-mediated transfer of human cytochromeP450 21-hydroxylase into the adrenal gland of21-hydroxylase-deficient mice.

21-Hydroxylase deficiency, a potentially fatal disease due to deletions or mutations of the cytochrome P450 21-hydroxylase gene (CYP21), causes congenital adrenal hyperplasia (CAH) with low or absent glucocorticoid and mineralocorticoid production. The feasibility of gene therapy for CAH was studied using 21OH-deficient mice (21OH-) and a replication-deficient adenovirus containing the genomic sequence of human CYP21 (hAdCYP21). Intra-adrenal injection of hAdCYP21 in 21OH- mice induced hCYP21 mRNA with the highest expression from 2 to 7 days before a gradual decline. 21OH activity measured in adrenal tissue increased from undetectable to levels found in wild-type mice 2 to 7 days after AdhCYP21 injection. Adrenal morphology of 21OH- mice showed lack of zonation, and hypertrophy and hyperplasia of adrenocortical mitochondria with few tubulovesicular christae. These morphological abnormalities were markedly improved 7 days after hAdCYP21 gene therapy. Plasma corticosterone increased from undetectable levels to values similar in wild-type mice by 7 and 14 days, declining over the next 40 days. This is the first demonstration that a single intra-adrenal injection of an adenoviral vector encoding CYP21 can compensate for the biochemical, endocrine and histological alterations in 21OH-deficient mice, and shows that gene therapy could be a feasible option for treatment of CAH.

Adenoviridae↗
PubMed1999

Origin of the gonad in the juvenile of a solitary ascidian, Ciona intestinalis.

In the just-metamorphosed juveniles of Ciona intestinalis, a round mass of tissue debris derived from the resorbed tadpole tail is situated in the broad space enclosed by the peritoneal membrane and the epidermis around the ventral side of the esophagus. In living juveni es, the origin of the gonad rudiment was traced back to the mass of tissue debris. Electron microscopically, the round mass was a clump of irregular-shaped phagocytotic cells engulfing degenerated cell fragments. On the surface of the cell clump, a small number of singly occurring round cells were found and identified as primordial germ cells on the basis of morphological continuity to obvious germ cells in later stages. Presence of nuage around the nucleus characterized the germ cells. In a few days the germ cells assembled to form a solid slender body (gonad rudiment) together with smaller somatic cells. The gonad rudiment left the space around the esophagus, moving into the narrow mesenteric space connecting the stomach and intestine on the fourth day after metamorphosis. It gradually increased in size by proliferation of the germ cells and somatic cells. The solid gonad rudiment changed into an oval vesicle with an eccentrically located cavity on about the seventh day after metamorphosis. The vesicle comprised a thinner wall made of a simple epithelium without germ cells and a thicker wall containing germ cells and somatic cells.

Animals↗
PubMed1999

Differentiation of the gonad rudiment into ovary and testis in the solitary ascidian, Ciona intestinalis.

In the early juveniles of Ciona intestinalis, primordial germ cells arise on the degenerated mass of the resorbed tadpole tail, and assemble to form a discrete gonad rudiment. The present study elucidated the morphological sequences during differentiation of the gonad rudiment into the testis and ovary. In 11- to 12-day juveniles, the gonad rudiment, an elongate sac, divided into the testicular and ovarian rudiments. The testicular rudiment separated as a round vesicle from the thickened wall of the elongate sac. The original sac, after separation of the round vesicle, developed into the ovary. In the testicular rudiment, germ cells formed a continuous central mass without association of somatic cells, while in the ovarian rudiment, each germ cell was associated with somatic cells within the epithelium composing the wall of the rudiment. In 13- to 15-day juveniles the testicular rudiment changed into branched tubes ending in club-shaped follicles. Cells characterized by many flattened cisternae of rough endoplasmic reticulum (distal cells) constituted the distal wall of each follicle. Spermatogenic cells were freely present in the follicular lumen, but the largest spermatogonia were in contact with the distal cells. Both in the testicular and ovarian rudiments, germ cells entered meiosis in 18-day juveniles. A novel body (periesophageal body) was found just beneath the ventral margin of the esophageal opening. It comprised irregular follicles made up of one cell type whose cytoplasm, filled with round vesicles and Golgi complexes, was suggestive of an endocrine function. Fragments derived from the periesophageal body were present around the developing ovary.

Animals↗
PubMed1999

Orthotopic ileal neobladder in male patients: functional outcomes of 66 cases.

BACKGROUND: Orthotopic urinary diversion has become the preferred form of bladder reconstruction after cystectomy. We report on our experience with 66 male patients undergoing this procedure from November 1990 to February 1998. METHODS: A neobladder was constructed using an ileal segment with a Hautmann type bladder. Complications were assessed and subdivided into early and late types. Voiding function was evaluated in terms of voiding pattern and continence. Median follow up was 19.5 (range 3.5-87.7) months. RESULTS: There was one (1.5%) perioperative death. The most frequent pouch-related and unrelated early complications were persistent urine leak (7.6%) and prolonged ileus (16.7%), respectively, the majority of cases of which were managed conservatively. Analysis of late complications revealed 6.2% ureteroileal stenosis and 1.5% urethrointestinal stenosis rates, but no case of bladder stone formation. Of the 61 patients in whom voiding function was evaluable, 95.1% achieved excellent daytime continence, while only 67.2% had night-time continence. With regard to posture at voiding, 23 (37.7%) voided in a sitting position. Three of the patients (4.9%) were unable to void and required regular intermittent catheterization. CONCLUSIONS: An orthotopic neobladder can be constructed with acceptable morbidity and excellent functional results. We believe that orthotopic urinary diversion offers an attractive alternative to a bladder substitute when cystectomy is required.

Adult↗
PubMed1999

Changes in resistive index following extracorporeal shock wave lithotripsy.

BACKGROUND: Extracorporeal shock wave lithotripsy (ESWL) has replaced most surgical and endourologic forms of therapy for upper urinary tract stone disease. Despite its proved safety and efficacy, its adverse effects on renal function are still to be identified. A newer diagnostic technique, color Doppler ultrasonography, has brought a new insight into renal function. It enables precise evaluation of the renal vascular supply. Changes in intrarenal vascular resistance after ESWL were studied with Doppler ultrasound techniques. METHODS: In 70 consecutive patients the resistive index (RI) was measured at an interlober artery before and 30 min after ESWL in the treated and contralateral kidneys. In 17 patients, a follow-up Doppler study was performed 1 week after ESWL. RESULTS: In the treated kidneys, the RI significantly increased from 0.656+/-0.053 (mean +/- SD) at baseline to 0.682+/-0.053 (P<0.0001). There was no significant correlation of increase in RI with patient age (r = 0.010) or with pre-ESWL blood pressure (r = 0.002). Elderly patients (> or =60 years old, n = 31) had higher RI levels on baseline than younger patients (<60 years old, n = 39). In 18 of the 31 (58.1%) elderly cases the RI were elevated to greater than 0.7, indicating pathologic changes. In younger patients, only 9 (23.1%) experienced increase in RI up to 0.7 or greater. The contralateral untreated kidneys showed significant change in RI before (0.664+/-0.045) and after (0.679+/-0.049) lithotripsy in elderly patients (P<0.005). A follow-up Doppler study showed that the mean RI returned to pretreatment levels after 1 week. CONCLUSIONS: Because of higher RI levels on baseline, elderly patients have a higher risk of post-ESWL renal tissue damage than younger patients. Clinical implication of RI change in the contralateral kidneys in this study remains to be answered. The measurement of changes in RI with Doppler ultrasound techniques after ESWL may provide useful information for clinical diagnosis of renal tissue damage.

Adolescent↗
PubMed1999

Urinary undiversion for pelvic actinomycosis: a long-term follow up.

BACKGROUND: A 43-year-old woman who had been using intrauterine contraceptive devices for the past 10 years underwent an emergency operation for bowel and urinary obstruction. METHODS/RESULTS: Frozen section analysis showed undifferentiated adenocarcinoma. Incomplete tumorectomy, ileal resection, partial cystectomy, colostomy and bilateral ureterocutaneostomy were palliatively performed. Postoperatively, periodic acid-Schiff and Grocott-Gomori methenamine tests revealed Actinomyces and the final diagnosis was pelvic actinomycosis. Treatment with penicillin G administered intravenously relieved her symptoms and the lesion was dramatically improved. The patient underwent colostomy closure and urinary undiversion. CONCLUSIONS: Five years after urinary undiversion, the patient's renal function has been maintained and she can void without incontinence and dysuria.

Actinomycosis↗