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Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 37 records · Page 2Linked to original sources
PubMed2003

Ruptured intercostal artery pseudoaneurysm after blunt thoracic trauma.

Here, we present the case of ruptured intercostal artery pseudoaneurysm two months after blunt thoracic trauma. Ruptured aneurysm hemorrhaged into the retroperitoneal space due to adhesion in the intrathoracic space. We unsuccessfully embolized the aneurysm during an angiographic procedure and performed the aneurysmectomy, removing the hematoma, using a retroperitoneal approach. Ruptured intercostal artery pseudoaneurysm after blunt thoracic trauma may have caused the delayed life-threatening hemorrhage.

Aged↗
PubMed2003

Expression of estrogen, progesterone and androgen receptors in the oviduct of developing, cycling and pre-implantation rats.

To determine expression and localization of receptors for estrogen (ER), progesterone (PR) and androgen (AR), detailed immunohistochemical evaluations were performed in the Sprague-Dawley rat oviduct during pre- and neonatal development, estrous cycle and pre-implantation period. In addition, real-time RT-PCR studies were conducted to evaluate changes in ERalpha, ERbeta, total PR (PR-A+B), PR-B and AR mRNA expressions. All receptors except for ERbeta were detected in epithelial, and stromal or mesenchymal cells of the fetal and neonatal oviduct, and increased with development. During the estrous cycle and early pregnancy, ERalpha and PR-A+B were expressed in epithelial, stromal and muscle cells throughout the oviduct region, and showed changes in expression predominantly in the isthmus. Only a few epithelial cells in the infundibulum (inf) and ampulla (AMP) showed ERbeta staining. AR was detected in stromal and muscle cells throughout the oviduct region, and in epithelial cells of the inf/AMP. Taken together, ERalpha, PR-A+B and AR were detected in the epithelium of the inf/AMP region, but all of these receptors were expressed in a distinct subset of epithelial cells which were negative for beta-tubulin IV, a ciliated epithelial cell marker. These results contribute to a better understanding of the respective roles of ERs, PRs and AR in the rat oviduct.

Animals↗
PubMed2002

Prenatal ultrasonographic appearance of type IIId (uncorrectable type with cystic dilatation) biliary atresia.

Although prenatal ultrasonographic (US) diagnosis has been reported in biliary atresia (BA), most cases are type I (correctable with cystic dilatation). We report three prenatal cases of type IIId BA (uncorrectable with cystic dilatation). Routine fetal US at 22 to 24 weeks of gestation showed two communicating cystic lesions 12 to 16 mm in diameter. On color Doppler US, the lesions were separate from the portal vein or hepatic artery. The size did not change during the prenatal period in any case. Choledochal cyst (CC) was considered the most likely diagnosis, although BA with cystic lesions was also considered. After birth, the patients developed acholic stools and prolonged neonatal jaundice. Hepatobiliary scintigraphy showed negative passage. Duodenal fluid showed a negative or slightly positive Gmelin test. The neonates underwent laparotomy at the age of 36, 46, and 32 days, respectively. Intraoperative cholangiography showed the gallbladder and slightly-dilated common-bile duct without entering the proximal or distal bile ducts in all cases. They were classified as type IIId BA and underwent excision of the cystic lesions and dissection of the portal bile-duct remnants, followed by hepatic portoenterostomy. Case 1 showed persistent jaundice and finally underwent liver transplantation (LTx), case 2 became anicteric. Case 3 remained jaundiced and is to undergo LTx. In conclusion, type IIId BA may be one of the differential diagnoses when a cystic lesion is detected under the hepatic hilum by fetal US. However, prenatal diagnosis of BA is still difficult with respect to differentiation from a CC or type I BA. Early postnatal diagnosis followed by immediate treatment is important, especially in type IIId BA.

Bile Ducts↗
PubMed2002

Experience with International Neuroblastoma Staging System and Pathology Classification.

The International Neuroblastoma Staging System and Pathology Classification were proposed in 1988 and in 1999, respectively, but their clinical value has not yet been fully studied in new patients. Six hundred and forty-four patients with neuroblastoma treated between January 1995 and December 1999 were analysed by these classifications. The 4-year overall survival rate of patients <12 months of age with INSS stages 1, 2A, 2B, 3 and 4S disease was 98.5%, which was significantly higher than the 73.1% rate in stage 4 patients <12 months (P<0.0001). When patients were > or = 12 months, the 4-year overall survival rate of patients with neuroblastoma at 1, 2A, 2B and 3 stages was 100% and that of patients at stage 4 was 48.5% (P<0.0001). As to the International Neuroblastoma Pathology Classification histology, the 4-year overall survival rate was 98.8% in patients with favourable histology and 60.7% in those with unfavourable histology in the <12 months group (P<0.0001). In the > or = 12 months group, the 4-year oral survival of patients with favourable histology was 95.3% and that of patients with unfavourable histology was 50.6% (P<0.0001). Among biological factors, MYCN amplification, DNA diploidy and 1p deletions were significantly associated with poor prognosis in patients <12 months, as were MYCN amplification and DNA diploidy in patients > or = 12 months of age. Multivariate analysis showed that the INSS stage (stage 4 vs other stages) and International Neuroblastoma Pathology Classification histology (unfavourable vs favourable) were significantly and independently associated with the survival of patients undergoing treatment, stratified by age, stage and MYCN amplification (P=0.0002 and P=0.0051, respectively).

Age Factors↗
PubMed2002

Mechanisms responsible for recurrent gastroesophageal reflux in neurologically impaired children who underwent laparoscopic Nissen fundoplication.

BACKGROUND: In this study, we attempted to define the lower esophageal sphincter (LES) motor events associated with the occurrence of gastroesophageal reflux (GER) in neurologically impaired children in whom of GER disease recurred after laparoscopic Nissen fundoplication (LNF). METHODS: Of 45 neurologically impaired children who had previously undergone LNF, six children in whom recurrence of GER disease was documented by 24-h esophageal pH monitoring were studied. Concurrent esophageal manometry and pH monitoring were conducted for 1 h both before and after the administration of apple juice (10 ml/kg). RESULTS: A total of 89 reflux episodes were recorded in the course of the study. Of these, 51 episodes (57%) were associated with transient LES relaxation. In the remainder, reflux occurred across a contracted LES in 21 episodes (24%) and during absent basal LES tone in 15 episodes (17%). In four of six patients, transient LES relaxation was responsible for more than half of the reflux episodes. CONCLUSION: Transient LES relaxation is the predominant mechanism of reflux in neurologically impaired children with recurrent GER after LNF.

Child↗
PubMed2002

Measurement of serum total bile acid levels in long-term postoperative follow-up of patients with congenital bile-duct dilatation.

Serum total bile acid levels (STBA), a sensitive indicator of cholestasis, were measured during the long-term postoperative period in patients with congenital bile-duct dilatation (CBDD) (choledochal cyst) and the factors contributing to elevation of STBA were analyzed in 44 patients. Their ages at operation ranged from 1 month to 16 years. A STBA level over 12 nmol/ml on two or more measurements during outpatient follow-up was considered abnormal. Patients were classified into three groups: group 1, STBA, 12-50 nmol/ml; group 2, STBA > or = 50 nmol/ml; group N, STBA normal. In 19 patients (43.2%) STBA was normal. Of the 25 patients (56.8%) with elevated STBA, groups 1 and 2 comprised 12 (27.3%) and 13 patients (29.5%), respectively. The mean age in group N was 5.1 +/- 4.2 years, which was higher than in groups 1 (2.6 +/- 2.3) and 2 (2.3 +/- 2.5 years) ( P< 0.05). Preoperative STBA and total bilirubin were higher in group 2 (79.2 +/- 75.1 nmol/ml resp. 5.2 +/- 4.2 mg/dl) than in groups N (20.1 +/- 32.6, 1.3 +/- 1.4) and 1 (22.8 +/- 37.2, 1.4 +/- 1.0) ( P< 0.05). Preoperative alkaline phosphatase and gamma-glutamyl transpeptidase were higher in group 2 (1,006 +/- 872 IU/l, 452 +/- 326 IU/l) than in group N (573 +/- 371, 205 +/- 238) ( P< 0.05). Histologic findings on liver biopsy showed fibrosis in 38.5% of group 2 patients, which was significantly higher than in groups N (15.8%) and 1 (16.7%) ( P< 0.05). Cholestasis was detected in 41.7% of group 1 and 61.5% of group 2 patients, compared to 10.5% of group N patients ( P< 0.05). Postoperative elevation of STBA may thus persist in more than one-half of patients with CBDD, and is likely to occur in patients of young age who have severe cholestasis or liver fibrosis preoperatively. Further investigations may be required in regard to the development of postoperative complications.

Adolescent↗
PubMed2002

Pulsed Doppler tissue imaging for the assessment of myocardial viability: comparison with 99mTc sestamibi perfusion imaging.

The aim of the present study was to examine whether Doppler tissue imaging demonstrated comparable diagnostic performance for the detection of viable myocardium compared to myocardial perfusion imaging with Tc hexakis-2-methoxyisobutylisonitrile (MIBI). We studied 30 patients with old myocardial infarction who underwent percutaneous transluminal coronary angioplasty (PTCA). Myocardial single photon emission computed tomography (SPECT) with Tc-MIBI and two-dimensional echocardiography were carried out within 7 days before PTCA. We measured regional Tc-MIBI uptake for each myocardial segment from SPECT and peak systolic velocity and a ratio of regional pre-ejection period to regional ejection time (PEP/ET) from pulsed Doppler tissue imaging. Biplane left ventriculography was performed before interventional procedures and repeated 3 months after PTCA. Myocardial viability was determined when wall motion was improved at least one grade after PTCA. The peak systolic velocity was positively correlated with regional Tc-MIBI uptake (R =0.59, P<0.01). The PEP/ET demonstrated inverse correlation with Tc-MIBI uptake ( R=-0.59, P<0.01). Peak systolic velocity of viable segments was higher than that of non-viable segments ( P<0.05). The PEP/ET was lower in viable segments than in non-viable segments ( P<0.05). Peak systolic velocity and PEP/ET demonstrated high diagnostic accuracy for detecting viable myocardium compared with Tc-MIBI perfusion imaging (80% and 79% vs 90%). These data indicate that measurements of regional peak systolic velocity and PEP/ET by Doppler tissue imaging are useful for evaluating myocardial viability quantitatively and provide helpful information for a clinical judgment in an interventional strategy.

Adult↗
PubMed2002

Semiquantitative analysis of corpus callosum injury using magnetic resonance imaging indicates clinical severity in patients with diffuse axonal injury.

OBJECTIVE: To evaluate the hypothesis that the extent of corpus callosum injury indicates the depth of shearing lesions in the central brain structure and therefore relates to the clinical severity of diffuse axonal injury. METHODS: A simple and objective procedure for semiquantitative analysis of magnetic resonance images (MRI)-the maximum signal intensity ratio (MSIR)-was employed prospectively in 21 patients with diffuse axonal injury but without apparent injury to the ventral pons. All were diagnosed using serial combination MRI scans of fluid attenuated inversion recovery (FLAIR) and T2* weighted gradient echo imaging during the initial two weeks after the injury. The signal intensity ratio between the two regions of interest-the corpus callosum and the normal appearing ventral pons-was calculated serially in mid-sagittal and parasagittal FLAIR image sections in each patient. The MSIR during the study period was determined as a semiquantitative index of corpus callosum injury in each patient. The correlations between MSIR and the duration of unconsciousness, Glasgow outcome scale at six months, and the presence of apparent midbrain injury were investigated. RESULTS: The mean (SD) MSIR value was 1.12 (0.18) at 7.4 (3.1) days after the injury (n = 21). MSIR correlated strongly with the duration of unconsciousness (n = 19, R(2) = 0.74, p < 0.0001), and was higher in patients with both an unfavourable GOS outcome (p = 0.020) and apparent midbrain injury (p < 0.001). CONCLUSIONS: MSIR, which is a simple and objective procedure for semiquantitative analysis of corpus callosum damage in diffuse axonal injury, correlated with clinical severity. A high MSIR value may indicate the presence of concomitant midbrain injury.

Adolescent↗
PubMed2002

Changes in ontogenetic expression of estrogen receptor alpha and not of estrogen receptor beta in the female rat reproductive tract.

To evaluate ontogenetic expression and localization of estrogen receptor (ER) alpha and beta in fetal female rat reproductive tract, competitive RT-PCR and immunohistochemistry were performed. Expression levels for Müllerian ERalpha, ERbeta1 and ERbeta2 mRNAs were determined by competitive RT-PCR. ERalpha expression on gestational day (GD) 15 x 5 increased 4 x 4-fold by GD 21 x 5, whereas both ERbeta1 and ERbeta2 gene expression were maintained at lower constant levels compared with ERalpha during development. ER immunolocalization was evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. Nuclear ERalpha was localized predominantly in proximal Müllerian epithelium, and middle and caudal Müllerian mesenchyme on GDs 15 x 5-21 x 5. Staining intensity for ERalpha increased with development in all regions. However, ERbeta immunoreactivity was not detected in any region during prenatal life after separate staining with three different polyclonal anti-rat ERbeta antibodies. These findings provide fundamental information critical for clarifying the species-specific physiological roles of ER subtypes during fetal development and for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen and estrogen receptor agonists.

Animals↗
PubMed2001

Preparation, structure, and amphoteric redox properties of p-phenylenediamine-type dyes fused with a chalcogenadiazole unit.

4,7-Bis(dialkylamino)benzo[c][1,2,5]chalcogenadiazoles are a novel class of organic dyes that undergo reversible two-stage one-electron oxidation as well as one-electron reduction. They exhibit absorption maxima in the long-wavelength region, which are assigned as intramolecular charge transfer bands from the phenylenediamine moiety to the electron-accepting heterocycle. Their redox properties as well as molecular and crystal structures are affected by the alkyl substituents on the amino nitrogen and/or by the chalcogen atom (O, S, Se) in the heterocycle.

Journal Article↗
PubMed2001

Successful laparoscopic fundoplication in children with ventriculoperitoneal shunts.

We reported successful laparoscopic fundoplication in 2 pediatric cases with VPS and discuss the safety and feasibility of the procedure. Case 1: A 13-year-old girl with VPS underwent laparoscopic fundoplication. Case 2: a 9-year-old boy with VPS underwent laparoscopic fundoplication. In both cases, laparoscopic Nissen fundoplication was performed with a standard five-port technique with a low pressure of a pneumoperitoneum. The VPS system had no effect on port layout and intraabdominal manipulation and no adverse complications were observed in either case. The effect of a pneumoperitoneum in the VPS system remains controversial, however, the author emphasized that advanced laparoscopic surgery can be performed safely with creating a low pressure of a pneumoperitoneum.

Adolescent↗
PubMed2001

Regulation of glutamine transport by the type I insulin-like growth factor receptor in a human neuroblastoma cell line.

We examined the effects of the monoclonal antibody against the type I insulin-like growth factor receptor (IGF-IR), alphaIR3, on cell growth and membrane glutamine (Gln) transport in a human neuroblastoma cell line, SK-N-SH. In the presence of alphaIR3 (2 microg/ml), the cell proliferation rate was significantly attenuated. Gln transport was decreased in the alphaIR3-treated group with the mechanism of decreasing maximum transport velocity without affecting transport affinity. The addition of alphaIR3 significantly decreased DNA and protein biosynthesis. Our results support the concept that the activation of IGF-IR partially mediates neuroblastoma cell proliferation by regulating membrane Gln transport.

Apoptosis↗
PubMed2001

Solar 8B and hep neutrino measurements from 1258 days of Super-Kamiokande data.

Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0-20.0 MeV. The measured solar neutrino flux is 2.32+/-0.03(stat)+0.08-0.07(syst)x10(6) cm(-2) x s(-1), which is 45.1+/-0.5(stat)+1.6-1.4(syst)% of that predicted by the BP2000 SSM. The day vs night flux asymmetry (Phi(n)-Phi(d))/Phi(average) is 0.033+/-0.022(stat)+0.013-0.012(syst). The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L. upper limit of 40x10(3) cm(-2) x s(-1), which is 4.3 times the BP2000 SSM prediction.

Journal Article↗
PubMed2001

Constraints on neutrino oscillations using 1258 days of Super-Kamiokande solar neutrino data.

We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way. Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found.

Journal Article↗
PubMed2001

Membrane-type 1 matrix metalloproteinase cleaves CD44 and promotes cell migration.

Migratory cells including invasive tumor cells frequently express CD44, a major receptor for hyaluronan and membrane-type 1 matrix metalloproteinase (MT1-MMP) that degrades extracellular matrix at the pericellular region. In this study, we demonstrate that MT1-MMP acts as a processing enzyme for CD44H, releasing it into the medium as a soluble 70-kD fragment. Furthermore, this processing event stimulates cell motility; however, expression of either CD44H or MT1-MMP alone did not stimulate cell motility. Coexpression of MT1-MMP and mutant CD44H lacking the MT1-MMP-processing site did not result in shedding and did not promote cell migration, suggesting that the processing of CD44H by MT1-MMP is critical in the migratory stimulation. Moreover, expression of the mutant CD44H inhibited the cell migration promoted by CD44H and MT1-MMP in a dominant-negative manner. The pancreatic tumor cell line, MIA PaCa-2, was found to shed the 70-kD CD44H fragment in a MT1-MMP-dependent manner. Expression of the mutant CD44H in the cells as well as MMP inhibitor treatment effectively inhibited the migration, suggesting that MIA PaCa-2 cells indeed use the CD44H and MT1-MMP as migratory devices. These findings revealed a novel interaction of the two molecules that have each been implicated in tumor cell migration and invasion.

Amino Acid Sequence↗
PubMed2001

Protonation of histidine and histidine-tryptophan interaction in the activation of the M2 ion channel from influenza a virus.

The M2 protein of influenza A virus forms a homotetramer ion channel in the lipid membrane. The channel is specific for proton conductance and is activated by low pH with a transition midpoint at pH 5.7. We have studied the structure of the transmembrane domain of the M2 ion channel by using UV resonance Raman spectroscopy, with special attention to the side chains of histidine (His37) and tryptophan (Trp41) residues. The Raman spectra provide direct evidence that the imidazole ring of His37 is protonated upon channel activation at low pH. Concomitantly, the UV resonance Raman scattering from Trp41 shows an unusual intensity change, which is ascribed to a cation-pi interaction between the protonated (cationic) imidazole ring of His37 and the indole ring of Trp41. The protonation of His37 and the Raman intensity change of Trp41 do not occur in the presence of amantadine that blocks the M2 ion channel. These observations clearly show that the protonation of His37 and concomitant cation-pi interaction with Trp41 is a key step in the activation of the M2 ion channel. The His37-Trp41 interaction associated with the channel activation is explained by assuming a conformational transition of His37 induced by electrostatic repulsion among the protonated imidazole rings of four His37 residues in the tetramer channel. Trp41 may play a role in stabilizing the channel open state through cation-pi interaction with His37. A molecular model for the activation of M2 ion channel is proposed on the basis of the gating mechanism.

Amantadine↗