Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 19 recordsLinked to original sources

PubMed2006

Pathophysiological role of endothelin in ectopic ossification of human spinal ligaments induced by mechanical stress.

Ossification of the posterior longitudinal ligament (OPLL) of the spine is characterized by progressive ectopic bone formation in the spinal ligament. To identify the genes related to ossification affected by mechanical stress during OPLL, analyses using cDNA microarray were carried out using cultured human spinal ligament cells that had been subjected to uniaxial cyclic stretching. Samples were obtained from a total of 14 patients: seven cervical or thoracic OPLL patients and seven control patients. Spinal ligament cells derived from tissues of OPLL (OPLL cells) and control (non-OPLL cells) patients were subjected to uniaxial sinusoidal cyclic stretching (0.5 Hz, 20% stretch) for various time periods (0-9 hours). cDNA microarrays revealed that ranges of distribution of both up- and downregulated genes evoked by cyclic stretching were significantly wider in OPLL cells than in non-OPLL cells. Increases in the mRNA expression of endothelin-1 (ET-1) as well as various marker genes related to ossification were also observed. mRNA expression of ET-1 and alkaline phosphatase was increased by mechanical stress in a time-dependent manner, while addition of ET-1 to static cultures of OPLL cells increased mRNA expression of alkaline phosphatase in a dose-dependent manner. During 9 hours of cyclic stretching, ET-1 release increased to about sixfold the amount observed in nonstretched cells. In non-OPLL cells, neither cyclic stretching nor ET-1 induced any increase in alkaline phosphatase expression. These results suggest that mechanical stress promotes the progression of ossification in OPLL cells through autocrine and/or paracrine mechanisms of ET-1.

Aged↗

PubMed2006

Oral behavior from food intake until terminal swallow.

We analyzed oral behavior from food intake until terminal swallow for mastication and swallowing under a freely eating condition with a natural food. Measurements, including movement of the mandible and tongue, the size of the gape, different sequences involved in the oral aspect of the swallowing action, and bolus size and movement were carried out in five "freely eating subjects" using videofluorography. During food intake, the tongue moved forwards and backwards to introduce food into the mouth, to compress the food against the hard palate, and to transport food to the occlusal surface of the molar teeth. Most of the food was swallowed in the first swallow, and any residual food was aggregated by the tongue into a bolus and then swallowed in the last swallow. These findings suggest that 1) tongue manipulation plays an important role in recognizing and evaluating the volume of bite taken, 2) the intra-oral compression of food has a role in the recognition of food texture, 3) stage I transport is closely bound to the texture recognition process, 4) humans need at least two swallows, even with one bite of food, when ingesting food freely, and 5) the duration time of the oral stage of swallowing may depend on the bolus volume and be longer for smaller volumes unlike those measured under the command swallow.

Adult↗

PubMed2006

Population research of genetic polymorphism at amino acid position 631 in chicken Mx protein with differential antiviral activity.

A single amino acid substitution between Asn and Ser at position 631 in the chicken Mx protein has been reported to determine resistant and sensitive antiviral activity. In this study, we investigate whether various kinds of chicken breeds and jungle fowls carry the resistant or sensitive Mx allelic gene by using the mismatched PCR-restriction fragment length polymorphism (RFLP) technique. In total, 271 samples from 36 strains of 17 chicken breeds and from 3 kinds of jungle fowls were examined. The rates of the resistant Mx gene and sensitive gene were 59.2% and 40.8%, respectively. Only a Red jungle fowl captured in Laos carried the resistant Mx gene, and the other three Red jungle fowls from Indonesia and Gray and Green jungle fowls all had the sensitive Mx gene. These results were confirmed by the determination of amino acid sequences in the GTPase effector domain of jungle fowls.

Alleles↗

PubMed2004

Evidence for an oscillatory signature in atmospheric neutrino oscillations.

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.

Journal Article↗

PubMed2004

Search for electron neutrino appearance in a 250 km long-baseline experiment.

We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline neutrino experiment. One candidate event is found in the data corresponding to an exposure of 4.8 x 10(19) protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4+/-0.6 events and is dominated by misidentification of events from neutral current pi(0) production. We exclude the nu(micro) to nu(e) oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin((2)2theta(microe)( approximately 1/2sin((2)2theta(13))>0.15 at Deltam(2)(microe)=2.8 x 10(-3) eV(2), the best-fit value of the nu(micro) disappearance analysis in K2K. The most stringent limit of sin((2)2theta(microe)<0.09 is obtained at Deltam(2)(microe)=6 x 10(-3) eV(2).

Journal Article↗

PubMed2004

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data.

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.

Journal Article↗

PubMed2004

The relationship between pregnancy outcome and smooth endoplasmic reticulum clusters in MII human oocytes.

BACKGROUND: During ICSI, we occasionally observe pronucleus sized translucent vacuoles. We investigated why these vacuoles occur and determined the effect on pregnancy outcome. METHODS: Translucent vacuole-positive oocytes and the corresponding cohort were examined by transmission electron microscopy (TEM) and histochemical staining with DiI and ER-Tracker. Stimulation methods, hormonal levels, patients' condition and grade of transferred embryos were compared between vacuole-positive and vacuole-negative cycles. RESULTS: By TEM, we confirmed that the vacuoles were tubular-type smooth endoplasmic reticulum clusters (sERCs). Numerous small sERCs were also observed in the oocytes from the same cohort. Veeck's grades of transferred embryos were higher in sERC-positive cycles and fertilization rate was similar to those of sERC-negative cycles. However, in sERC-positive cycles, significantly lower pregnancy and higher biochemical pregnancy rates were shown. Serum estradiol levels on the day of hCG administration were significantly higher in sERC-positive cycles. CONCLUSIONS: The presence of sERCs is associated with lower chances of successful pregnancy, even in sERC-negative oocytes from the same cohort that are transferred along with the sERC-positive oocytes. High estradiol levels could be one of the causes of sERC formation.

Cohort Studies↗

PubMed2004

Clinical outcome of laparoscopically assisted endorectal pull-through in Hirschsprung's disease: comparison of abdominal and perineal approaches.

BACKGROUND/PURPOSE: Laparoscopically assisted endorectal pull-through (EPT) via a perineal approach using a prolapsing technique (PA) for Hirschsprung's disease (HD) has been reported. However, the clinical outcome after this approach has not been reported. The purpose of this study was to compare the clinical outcome of PA and the conventional transabdominal approach (TA). METHODS: In the period between 1990 and 2001, 20 cases of HD underwent EPT with TA (group O), and 21 underwent EPT with PA (group L). There was no difference in age and weight distribution between the 2 groups. Clinical outcome was assessed 3 years after surgery. RESULTS: The operation time was comparable in the 2 groups (4.9 +/- 0.8 v 5.2 +/- 0.8 hr), whereas blood loss (98 +/- 52 v 36 +/- 30 mL) and postoperative complications requiring surgical intervention (26% v 0%) were significantly lower in group L. The incidence of postoperative enteritis (27% v 28%) and voluntary defecation (more than once every/2 days) were compatible in the 2 groups (70% v 87%). Soiling (small amount of involuntary stooling; >1 per month) was significantly less frequent in group L (45% v 14%). CONCLUSIONS: Laparoscopically assisted ETP with PA is less invasive and can provide a better clinical outcome compared with TA in terms of postoperative soiling.

Abdomen↗

PubMed2004

Role of foxj1 and estrogen receptor alpha in ciliated epithelial cell differentiation of the neonatal oviduct.

Estrogen regulates proliferation and differentiation of epithelial cells in the mammalian oviduct, but pathways for cell-specific differentiation are not well understood. In the epithelial cells of the developing rat oviduct, we found estrogen receptor (ER) alpha is expressed at birth and persists in all cells through neonatal day (ND) 7 when ciliated cells appear. To determine a specific function of ER and foxj1, a transcription factor known to have fundamental roles in ciliogenesis in the lung, in differentiation of the ciliated epithelial cells, we treated newborn rats from ND 0 to 5 with estradiol-17beta (E2) with and without a selective ER antagonist. E2 enhanced the number of proliferating cells and accelerated the process of epithelial cell differentiation resulting in ciliogenesis by ND 5, and co-treatment with an ER antagonist inhibited these changes. Foxj1 was expressed only in the infundibulum and ampulla (INF/AMP). That expression preceded the appearance of cilia and was induced by E2. Cilia were absent in oviducts of foxj1-deficient mice, indicating that foxj1 plays a critical role in oviductal ciliogenesis. However, we found the presence of cilia in the ERalpha-deficient mouse oviduct. The widespread expression of ERalpha in oviductal epithelium, but restriction of cilia to the INF/AMP regions, and importantly, the presence of cilia in the ERalpha-deficient mice, suggested ER signaling is not essential for ciliated epithelial cell differentiation. These observations demonstrate that, although E2 stimulates the differentiation process of ciliated epithelial cells, foxj1 is directly required for epithelial cell ciliogenesis of the neonatal oviduct.

Animals↗

PubMed2004

[Limited resection for small peripheral lung cancer using intraoperative pathologic examination].

From 1996 to 2002, we performed intentional limited resection for small peripheral lung cancer using intraoperative pathologic examination. Wedge resection was performed in patients who had small peripheral adenocarcinoma (< or = 20 mm), suspected of being Noguchi type A or B, and confirmed by intraoperative pathologic examination. Extended segmentectomy was performed in the rest of patients (tumor diameter < or = 20 mm), and not suspected of being Noguchi type A or B. Hilar and mediastinal lymph nodes sampling was performed in this group. If lymph node metastasis was detected by the intraoperative pathologic examination, the surgical procedures was converted into a lobectomy with lymph node dissection. Limited resection was performed in 27 patients, wedge resection in 8, and extended segmentectomy in 19. All patients received wedge resection are alive without sign of recurrence. In extended segmentectomy, 17 patients are alive with no evidence of disease, 1 patient died of non-pulmonary disease, and 1 patient is alive with recurrent disease. The overall survival rate at 5 years was 100% in wedge resection, 91% in extended segmentectomy, and 79% in standard lobectomy. We conclude that limited resection for small peripheral lung cancer using intraoperative pathologic examination may be safe and effective procedure.

Adenocarcinoma↗

PubMed2004

[Intentional limited resection for small adenocarcinoma with ground-glass opacity component more than 50% on computed tomography].

Fifty-eight patients who had small lung tumors 2 cm or less with ground-glass opacity (GGO) component more than 50% on high resolution computed tomography (HRCT) underwent intentional limited resection. After bronchioloalveolar carcinoma without both active fibroblastic proliferation and invasive sign to the stroma was confirmed, limited resection was completed in 50 patients. In 8 patients, procedure was converted lobectomy because of microscopic invasive sign in 4, active fibroblastic proliferation in 2, and other reasons in 2. Unexpected invasive sign was found by detailed post-operative examination in 2 cases. Five-year survival rate was 98% with a mean follow-up period of 48.8 months. A limitation of intra-operative diagnosis was revealed and the accuracy of diagnosis should be improved by not only intra-operative pathological diagnosis but also HRCT images.

Adenocarcinoma↗

PubMed2003

Search for nu(e) from the sun at Super-Kamiokande-I.

We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.

Journal Article↗

PubMed2003

Indication for redo hepatic portoenterostomy for insufficient bile drainage in biliary atresia: re-evaluation in the era of liver transplantation.

To determine the role of redo hepatic portoenterostomy (HPE) in biliary atresia (BA) patients with insufficient bile excretion after the initial HPE, 25 patients (type I, correctable: 2; type III, uncorrectable: 23) undergoing the initial HPE at 25 to 119 days of age were studied. Four patients achieved disappearance of jaundice (total bilirubin [T.Bil] < 2 mg/dl) postoperatively. A redo HPE was performed at 2 to 8 months of age with sufficient and extensive removal of granulation and scar tissue at the hepatic hilum. Five patients became free of jaundice in 3 to 6 months (group 1), while the remaining 20 did not (group 2). Disappearance of jaundice after the initial HPE had been achieved in 2 of 5 patients (40%) in group 1 and 2 of 20 (10%) in group 2 ( P < 0.05). Age, serum T.Bil, aspartate aminotransferase albumin, prothrombin time, cholinesterase, total cholesterol, and Fischer's ratio at redo HPE showed no significant differences between the two groups. On liver histology obtained at redo HPE, cirrhosis and hepatocyte degeneration were seen in 1 of 5 cases (20%) in group 1 and 12 of 20 (60%) in group 2 ( P < 0.05). Redo HPE may thus be effective in BA patients with insufficient bile drainage who achieved disappearance of jaundice after the initial HPE and have not developed cirrhosis.

Biliary Atresia↗

PubMed2003

Search for supernova relic neutrinos at Super-Kamiokande.

A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.

Journal Article↗

PubMed2003

Indications of neutrino oscillation in a 250 km long-baseline experiment.

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Journal Article↗

PubMed2003

Proposal of fibrosis index using image analyzer as a quantitative histological evaluation of liver fibrosis in biliary atresia.

This study was designed to elucidate whether the fibrosis index (FI), which was measured as a ratio of histological fibrotic tissue area to the whole area using an image analyzer, could reflect liver function and long-term prognosis in biliary atresia (BA). Liver biopsies were performed in 46 BA patients at hepatic portoenterostomy (HPE) and stoma closure. The chronological difference rate of FI (FIDR) was the monthly FI difference between HPE and stoma closure. FI at HPE and stoma closure was significantly higher than in the control. FI at HPE and at stoma closure significantly correlated with gammaGTP or T.Bil, D.Bil, cholinesterase and total bile acid, respectively. FIDR in jaundice-free group was significantly lower than in jaundiced group at 5 years after HPE. FIDR in V-2 (varices with red-color sign) was significantly higher than in V-0 (no varices) or V-1 (varices without red-color sign). ICG-K value significantly correlated with FIDR. FI at stoma closure or FIDR was significantly lower in living patients than in patients who eventually died or underwent liver transplantation. In conclusion, FI can reflect the degree of cholestasis in BA. FIDR would be useful for predicting long-term outcome in BA.

Analysis of Variance↗

PubMed2003

Pancreaticobiliary maljunction: retrospective and nationwide survey in Japan.

Pancreaticobiliary maljunction (PBM) is a congenital anomaly defined as a union of the pancreatic and biliary duct that is located outside the duodenal wall. The Japanese Study Group on Pancreaticobiliary Maljunction and the Committee for Registration enrolled and analyzed 1627 patients with PBM who had been diagnosed and treated from January 1, 1990 to December 31, 1999 at 141 hospitals throughout the country. There were 1239 patients with dilatation of the bile duct (group A) and 388 patients without dilatation (group B). The average age was 24 years in group A and 47 years in group B; the age was significantly higher in group B. The type of confluence between the terminal choledochus and the pancreatic duct has been classified into three types (type a, right-angle type; type b, acute-angle type; and type c, complex type). In group A, type a accounted for 57.9% and was significantly more frequent compared with the other types (type b, 32.4%; type c, 5.6%). In group B, type b accounted for 60.8%, being significantly more frequent compared with the other types (type a, 29.4%; type c, 7.2%). Subjective symptoms, preoperative complications (e.g., liver dysfunction and acute pancreatitis), pancreatic stone, and pancreatic duct morphological abnormality were significantly more frequent in group A. However, the amylase levels in the bile and gallbladder were significantly higher in group B, and the presence of gallstone and morphological abnormality of the gallbladder was significantly more frequent in group B. The occurrence rate of cancer in the biliary tract was 10.6% in group A and 37.9% in group B, being significantly higher in group B. In group A, cancer of the extrahepatic bile duct was seen in 33.6% and cancer of the gallbladder was seen in 64.9%, but gallbladder cancer was present significantly more frequently in the patients with diffuse or cylindrical dilatation, and bile duct cancer was present significantly more frequently in the patients with cystic dilatation. In group B, 93.2% of the patients had gallbladder cancer, and bile duct cancer was found in as few as 6.8%. Against this background Japanese surgeons regard cholecystectomy, resection of the extrahepatic bile duct, and hepaticojejunostomy as standard operations for PBM with dilatation of the bile duct. However, opinion on whether or not the bile duct should be removed in the treatment of PBM without dilatation of the bile duct has been divided among Japanese surgeons. A randomized controlled trial is necessary.

Adolescent↗

PubMed2003

Endorectal pull-through with posterior sagittal approach to the repair of postoperative rectourethral and rectovaginal fistula.

BACKGROUND/PURPOSE: Rectourethral (RUF) or rectovaginal fistula (RVF) is a troublesome complication after anorectal surgery because of dense adhesions around the fistula. The authors applied a new technique for the redo surgery. METHODS: Case 1 is Hirschsprung's disease in a 1-year-old boy who underwent modified Duhamel's procedure and had RUF. Case 2 is rectovestibular fistula in an 11-year-old girl who had anterior sagittal anorectoplasty complicated by RVF. Case 3 is multiple urogenital anomalies including rectovesical fistula in a 4-year-old boy in whom transvesical repair was unsuccessful. The colon was mobilized as far as possible at laparotomy. The rectum was opened via a posterior sagittal approach leaving 1 cm of the anal canal. Extended endorectal mucosectomy was performed to the dentate line, and the fistula was closed from inside of the rectum. The remaining mucosal cuff was everted out of the anus and the intact colon was pulled through the rectum and anastomosed to the cuff extraanally. RESULTS: The postoperative contrast enema showed no recurrent fistula, and defecation was not impaired. CONCLUSIONS: Endorectal pull-through of the intact colon can spare troublesome mobilization of the fistula and can prevent the recurrence of fistula. Rectal incision via a posterior sagittal approach provides a direct view of the fistula.

Child↗