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R Ohi

Publications and source records attributed to R Ohi.

At least 19 recordsLinked to original sources
PubMed2004

Bipolarization and poleward flux correlate during Xenopus extract spindle assembly.

We investigated the mechanism by which meiotic spindles become bipolar and the correlation between bipolarity and poleward flux, using Xenopus egg extracts. By speckle microscopy and computational alignment, we find that monopolar sperm asters do not show evidence for flux, partially contradicting previous work. We account for the discrepancy by describing spontaneous bipolarization of sperm asters that was missed previously. During spontaneous bipolarization, onset of flux correlated with onset of bipolarity, implying that antiparallel microtubule organization may be required for flux. Using a probe for TPX2 in addition to tubulin, we describe two pathways that lead to spontaneous bipolarization, new pole assembly near chromatin, and pole splitting. By inhibiting the Ran pathway with excess importin-alpha, we establish a role for chromatin-derived, antiparallel overlap bundles in generating the sliding force for flux, and we examine these bundles by electron microscopy. Our results highlight the importance of two processes, chromatin-initiated microtubule nucleation, and sliding forces generated between antiparallel microtubules, in self-organization of spindle bipolarity and poleward flux.

Animals↗
PubMed2004

Choline acetyltransferase activity and evoked spinal cord potentials for diagnosis of brachial plexus injury.

The purpose of this study is to investigate the diagnostic value of evoked spinal cord potentials (ESCPs) and choline acetyltransferase (CAT) activity during exploration of injuries to the brachial plexus. We assessed 25 spinal roots in 19 patients. The results of the two investigations were consistent in all except two roots. Although assessment of ESCPs is easy and quick, it mainly records the nerve potentials along the sensory pathway. Although measurement of CAT activity needs a specimen of the nerve and the availability of a radioisotope laboratory, it gives direct information regarding the motor function of ventral spinal roots. These two techniques should be complementary to each other in order to achieve a more accurate diagnosis.

Adolescent↗
PubMed2001

CD8+ T cells infiltrating into bile ducts in biliary atresia do not appear to function as cytotoxic T cells: a clinicopathological analysis.

It is speculated that immune mechanisms are involved in bile duct damage in biliary atresia (BA), as in primary biliary cirrhosis (PBC). In BA, however, no reports have described the in situ distribution of cytotoxic T lymphocytes (CTLs) using specific markers, nor has the clinical association been clarified. The present study describes the immunohistochemical distribution of CD8+ T cells and the relevant markers [perforin, granzyme B, FasL (CD95L)] in 47 cases of BA operated upon at days 12-79. The results were compared with those of PBC. In BA, CD8+ T cells infiltrated bile ducts in a way similar to that observed in PBC. However, in sharp contrast to PBC, none of the inflammatory cells infiltrating into the bile ducts in BA expressed cytotoxic markers such as perforin, granzyme B, or Fas ligand (FasL). Clinical follow-up of patients with BA revealed that a greater degree of infiltration of bile ducts by CD8+ T cells is associated with better liver function. Taken together, these data suggest the absence of direct CTL activity against bile ducts in BA in the postnatal period.

Adolescent↗
PubMed2001

Clinical significance of c-kit expression in biliary atresia.

The aim of the present study was to examine the clinical significance of c-kit expression in biliary atresia (BA) using formalin-fixed, paraffin-embedded sections from 21 patients with BA. Patients were divided into group I (n = 8) with good liver function; group II (n = 8) with moderate liver dysfunction; and group III (n = 5) with severe liver dysfunction. Choledochal cysts (CDC, n = 5) and normal liver samples (NL, n = 4) served as controls. The results were analyzed and compared among the groups. Most c-kit+ cells were present in the portal tracts, and their numbers in BA were significantly higher than in the controls (11.12 +/- 1.64 vs 2.15 +/- 0.15 [mean +/- standard error], P = 0.02, BA vs CDC; 11.12 +/- 1.64 vs 1.66 +/- 0.52, P = 0.03, BA vs NL). Clinical correlation revealed a significantly higher number of c-kit+ cells in group III versus group I (18.10 +/- 3.62 vs 8.86 +/- 2.51, P = 0.02). These results suggest that c-kit overexpression is associated with an adverse clinical outcome in BA.

Biliary Atresia↗
PubMed2001

Surgery for biliary atresia.

Although the prognosis of biliary atresia has been improved in recent years, particularly in the era of liver transplantation, hepatic portoenterostomy, e.g., the Kasai operation, is still the first line of surgical treatment. Successful hepatic portoenterostomy depends on early diagnosis and operation, adequate operative technique, prevention of postoperative cholangitis, and precise postoperative management. The pathophysiology of the liver and of the intrahepatic bile ducts in this disease is still controversial.

Biliary Atresia↗
PubMed2001

Cytokeratin subtypes in biliary atresia: immunohistochemical study.

The etiology of biliary atresia (BA) remains unknown, but ductal-plate malformation and insufficient ductal-plate remodeling have been suggested to play important roles, so it is beneficial to examine the maturation and differentiation of bile ducts in BA. Different epithelial types are characterized by the expression of specific cytokeratin (CK) subtypes. CK can therefore serve as a 'lineage marker' of epithelial cells. CK subtypes have not been previously examined in BA. In this study, we examined the maturation of bile-duct cells in BA (n = 45) using immunohistochemistry of CK subtypes, with mouse monoclonal antibodies to CAM5.2, and CK subtypes 7, 8, 13, 14, 17, 19 and 20. We then compared these findings with pediatric non-BA (n = 11) and fetal (n = 21) liver. We semiquantitatively evaluated the findings using a H score method. In the fetal liver, immunoreactivity for CAM5.2, CK-7, CK-8 and CK-19 was detected in bile-duct cells, and CAM5.2 and CK-8 immunoreactivity was also detected in hepatocytes. The distribution of these CK subtypes was the same in fetal, pediatric non-BA and BA liver. However, CK-7 immunoreactivity was markedly weaker in bile ducts of fetal (H scores: ductal plate 0 +/- 0; remodeling 9.5 +/- 40.3; remodeled 37.3 +/- 60.8) and BA (H score: 200.9 +/- 55.3) liver compared to non-BA liver (H score: 251.1 +/- 33.5). In addition, CK-20 was detected in the bile ducts of the fetal and BA liver, but not in non-BA liver. These findings suggest that the expression patterns of CK subtypes in bile-duct cells in BA are similar to that in developing bile-duct cells, which is indicative of bile-duct cell immaturity.

Bile Ducts, Extrahepatic↗
PubMed2001

E-cadherin, alpha-catenin and beta-catenin in biliary atresia: correlation with apoptosis and cell cycle.

Biliary atresia (BA) is the most common cause of obstructive jaundice in infancy. Although the etiology of BA remains unknown, the ductal plate malformation has been considered to play an important role in the development of BA. Cell-cell adhesion has long been recognized as one of the most important processes in organogenesis. E-cadherin is involved in cell-cell adhesion, together with the catenins. Abnormalities of E-cadherin and associated catenins have not been examined in detail in the liver with BA. We therefore examined immunolocalization of E-cadherin and alpha- and beta-catenins in the BA liver (n = 45) and compared the findings with those in non-BA (n = 11) and fetal liver (n = 21). We semiquantitatively evaluated the findings using H score, which were generated according to the percentage of immunopositive cells and their immunointensity. We also examined mRNA localization of E-cadherin using mRNA in situ hybridization. We then studied the correlation of E-cadherin immunoreactivity with apoptotic cells, and cyclin-dependent kinase inhibitor p27Kip1 immunolocalization of bile duct cells in BA liver (n = 10) and fetal liver (n = 10). In fetal liver, H score of E-cadherin, but not of alpha- and beta-catenins, was significantly lower in the remodeling stage than in the ductal plate (P = 0.0034) and remodeled stages (P = 0.0024). In addition, the H score of E-cadherin, but not alpha- and beta-catenin, in bile duct cells was significantly lower in BA liver than in non-BA liver (P = 0.0132). E-cadherin mRNA hybridization signals were relatively conserved in bile duct cells of BA liver, but decreased in remodeling ductal plate cells of fetal liver. An inverse correlation was detected between the H score of E-cadherin and the TUNEL labeling index (LI) in both fetal and BA liver. In contrast, a positive correlation was detected between the H score of E-cadherin and p27 LI in both fetal and BA liver. These findings suggest that impaired expression of E-cadherin in bile ducts may play an important role in the biological features of BA, possibly associated with cell cycle and apoptosis.

Apoptosis↗
PubMed2001

Clinical application of intraoperative measurement of choline acetyltransferase activity during functioning free muscle transfer.

Intraoperative measurement of choline acetyltransferase (CAT) activity was used for evaluation of the functional status of donor nerves during functioning free muscle transfer (FFMT). Twelve patients underwent the procedure. Seven patients had a brachial plexus injury, 3 Volkmann's contracture, 1 chronic peroneal nerve injury, and 1 forearm extensor muscle loss after wide resection of soft tissue sarcoma. The purpose of reconstruction using FFMT was to achieve wrist extension in 4 patients, simultaneous elbow flexion and finger extension in 3, elbow flexion in 2, finger extension in 1, finger flexion in 1, and ankle extension in 1 patient. The gracilis muscle was transferred in all cases. The donor nerves for FFMT that were evaluated by CAT activity included 5 spinal accessory nerves, 4 posterior interosseous nerves, 2 anterior interosseous nerves, and 1 deep peroneal nerve. Fascicles with greater than 2,000 cpm CAT activity were considered to reliable and used as donor motor nerves. All muscles had reinnervation by 3.2 months (range, 2-5 months) and obtained useful recovery. Intraoperative measurement of CAT activity can provide direct and quantitative information about the functional status of donor nerves during FFMT.

Adolescent↗
PubMed2001

In situ CD14 expression in biliary atresia: comparison between early and late stages.

PURPOSE: The aim of this study was to compare the in situ expression of CD14 between early and late stage of biliary atresia (BA) to determine if a time course of CD14 expression exists in BA. METHODS: Immunohistochemical analysis of membrane-bound CD14 expression was carried out in periodate-lysine-paraformaldehyde (PLP)-fixed frozen sections from 9 early- (obtained during Kasai procedure) and 6 late- (obtained during liver transplantation) stage cases of BA. Normal liver (n = 3) and choledochal cysts (n = 5) served as normal controls and disease controls respectively. RESULTS: In the early stage, 6 patients (66.66%) showed extensive CD14 expression (grade 3 [G(3)], more than 50% positive cells), whereas no CD14-positive cells could be detected in 4 patients (66.66%) in the late stage. In both stages, most of the positive cells were observed in the parenchyma of the hepatic lobules where Kupffer cells and sinusoidal endothelial cells stained positive. Arterial and venous endothelium, bile duct cells, and hepatocytes were negative for CD14. Double immunohistochemistry in the early stage showed a higher colocalization rate of CD14 and CD68 in the sinusoidal locations (33.69 +/- 9.270% [mean +/- SEM]) than in the portal tract (7.6+/-4.64% [mean +/- SEM]; P<.05). Similar pattern of colocalization also was observed in the late stage. In the normal controls no expression of CD14 could be detected, whereas in the disease controls only 1 case showed mild expression (grade 1 [G(1)], 1% to 10% positive cells) and the rest showed no expression of CD14. CONCLUSION: These results suggest that CD14 expression in BA is a dynamic phenomenon having time-related change with overexpression in the early stage and reduced expression in the late stage.

Adolescent↗
PubMed2001

Problems during and after pregnancy of former biliary atresia patients treated successfully by the Kasai procedure.

BACKGROUND/PURPOSE: The aim of this study was to investigate the problems and the quality of life during and after pregnancy of the patients who had undergone Kasai operation and to find out a strategy for follow-up during the period of their pregnancy. METHODS: A questionnaire was sent to 134 institutions of the Japanese Biliary Atresia Society with the following questions: (1) Do you have any pregnancy cases in patients who had undergone Kasai operation? (2) Did she have any menstrual problem? (3) Did she have any problem during pregnancy and delivery? (4) Did she have any change in liver function tests after delivery? (5) Did she have any early and long-term problem after delivery? (6) Did the baby have any problem? (7) Was there any special care or comment about the pregnancy of the biliary atresia patients? The responses were analyzed. RESULTS: Fourteen institutions reported 16 cases of pregnancy, 23 cases of delivery, and 2 cases of abortion. The causes of abortion in the 2 cases were attributed to hemorrhagic shock after massive bleeding from esophageal varices and serious atopic dermatitis, respectively. Other problems during pregnancy were abruption of placenta, fetal distress leading to caesarian section, and development of liver dysfunction leading liver transplantation. Problems after delivery included deterioration of liver function in 6 patients (37.5%), attacks of ascending cholangitis in 4 patients (25.0%), and severe fatigue with liver dysfunction from nursing the baby leading to liver transplantation. Only 3 of 16 (18.8%) patients were free of any problems. No abnormality was seen in the babies. CONCLUSIONS: Even if the patients with biliary atresia lead a good postoperative course, unexpected complications can occur when they become pregnant. Close long-term follow-up is required for proper management of pregnancy in biliary atresia patients.

Adolescent↗
PubMed2001

Survival patterns in biliary atresia and comparison of quality of life of long-term survivors in Japan and England.

BACKGROUND/PURPOSE: Portoenterostomy is an accepted method of achieving bile drainage in biliary atresia, but there is a paucity of data, including formal quality-of-life (QoL) studies, on long-term survivors. This report includes survival analysis and QoL studies from the world's largest series of cases treated in Japan (1951 to 1998). The Japanese QoL results are compared with a matched group of UK patients from King's College Hospital, London. METHODS: One hundred fifteen Japanese surviving portoenterostomy patients were studied and comparison of trends in survival calculated from 6-year period cohorts. Liver function and hematologic status in a group of 30 long-term survivors (14 to 24 years) were compared with 25 patients from England, (14 to 23 years). Twenty-five Japanese and 21 UK patients (SF-36) completed a QoL questionnaire. RESULTS: Median survival times in Japanese patients before 1975 were less than 1 year but increased to 18 years after 1975. Hematologic and liver function test results did not show any significant differences between the Japanese and UK patients. QoL studies in the UK patients showed no significant difference from normative, general population data. Japanese patients underperformed in general health (P = .01), role emotional (P = .05) and role physical (P = .07) but, overall, there was no significant difference between the Japanese and UK patients except for marginal differences in indices of general health and vitality (P = .06 and .04, respectively). CONCLUSIONS: Long-term survival rate in the Japanese patients increased dramatically from 1 year to 17 years after 1975. The QoL of survivors was comparable in Japan and England. The satisfactory comparison with normative population data suggests that we should continue to use portoenterostomy as the primary treatment for biliary atresia. J Pediatr Surg 36:892-897.

Adolescent↗
PubMed2001

Improved survival of children with advanced neuroblastoma treated by intensified therapy including myeloablative chemotherapy with stem cell transplantation: a retrospective analysis from the Tohoku Neuroblastoma Study Group.

In the hospitals of the Tohoku Neuroblastoma Study Group (TNBSG), treatment for children with advanced neuroblastoma (NB) was intensified in the mid-1990's with the introduction of myeloablative therapy (MT) with stem cell transplantation (SCT) including the use of autologous peripheral blood stem cells (PBSC) and bone marrow transplantation (BMT). In this report, we examined whether the intensified therapy improved the outcome of children with advanced NB (age> 12 months) who were diagnosed between 1991 and 1997. Patients were 36 children (23 boys and 13 girls) with an average age of 3.4 years (range; 1 to 14 years). Six of them had stage III disease, and the other 30 had stage IV. They were treated initially with induction chemotherapy, surgery, and post-operative chemoradiotherapy, after which 17 of them continued further chemotherapy and the other 19 received MT/SCT (18 with PBSCT and 1 with BMT). Progression-free survival (PFS) rate at seven years from diagnosis was 43.5% for all patients, 66.7% for stage III patients and 38.2% for stage IV patients. The difference between stage III and IV patients was not significant. Among the 30 patients with stage IV disease, PFS at seven years was significantly higher in the 19 patients who received MT/SCT (55.6%) than in the 11 patients who did not receive it (12.5%). There was no difference in clinical and biological risk factors between these two groups, except for the proportion of patients with favorable response to initial therapy (36% and 80% for patients without and with MT/SCT, respectively). Furthermore, the proportion of patients with N-myc amplification was significantly higher in patients with progressive disease (PD) after MT/SCT than in those in CR after MT/SCT. The results of this retrospective study of children with advanced NB suggest that therapy intensification involving MT/SCT might result in lengthened survival time for patients with stage IV disease, and that post-transplant PD remains a risk for patients with high levels of N-myc amplification.

Antineoplastic Agents↗
PubMed2001

High trough levels of oral FK506 induced by loss of small intestine.

To establish a safe and effective usage of oral tacrolimus (FK506) in small bowel transplantation (SBTx) recipients, trough levels and area under the curve (AUC) values of FK506 were assessed using swine models of SBTx and short bowel. Thirty-eight Landrace male piglets were divided into four groups as follows: Group 1, controls (n=13); Group 2, a one-third small bowel model (n=5); Group 3, a short bowel model (n=10); and Group 4, a one-third small bowel allograft model (n=10; five donors and five recipients). Piglets of Groups 1 and 3 were further divided into two sub-groups, according to the route of drug administration: Groups 1a (n=10) and 3a (n=7) received FK506 orally, and Groups 1b (n=3) and 3b (n=3) received FK506 intravenously. Oral or intravenous FK506 was started on post-operative day 3 and continued until day 7 in each group. On day 7, trough levels and AUC values were measured. In Groups 1a, 2, 3a and 4, trough levels of FK506 were 2.1+/-1.2 (p<0.01 vs. Group 2, 3a or 4), 11.2+/-2.1, 23.3+/-4.8 (p<0.05 vs. Group 2 or 4) and 14.6+/-3.0 ng/mL, and AUC values were 101+/-90 (p<0.01 vs. Group 3a or 4), 319&+/-155, 808+/-200, and 531+/-113 ng.h/mL, respectively. Both trough levels and AUC values were lowest in Group 1a and highest in Group 3a. Between Groups 1b and 3b, there was no significant difference in the blood levels of intravenous FK506. The shorter the functioning residual small intestine was, the higher the trough level of oral FK506 was, while the presence or absence of small intestine did not affect blood levels of intravenous FK506. These results suggest that oral FK506 is metabolized in the functioning small intestine during its absorption. Therefore, events which cause intestinal malfunction, such as graft rejection in SBTx, inflammation and loss of small intestine, may adversely raise the trough level of oral FK506.

Animals↗
PubMed2000

In situ expression of fibrogenic growth factors and their receptors in biliary atresia: comparison between early and late stages.

Progressive fibrosis, despite successful surgical treatment, is one of the serious complications of biliary atresia. To understand the mechanism of this fibrosis, the in situ expression of fibrogenic growth factors (TGF-beta and PDGF) and their corresponding receptors was studied by immunohistochemistry using frozen sections. The results were compared between the early (n=12) and late (n=6) stages. The early stage was characterized by abundant expression of all ligands and receptors, together with type I procollagen (PC-I). The major cellular sources were activated fibroblasts/myofibroblasts distributed mostly in the portal tracts. Macrophages also expressed all the ligands and the receptors, but to a lesser degree. Bile duct cells strongly expressed TGF-beta RI and RII and PDGF AA and BB, but focally expressed TGF-beta. All of these decreased in the late stage of biliary atresia. These results suggest that TGF-beta and PDGF play important roles in the fibrogenesis of biliary atresia, especially in its early stage, acting either by autocrine or paracrine mechanisms involving activated fibroblasts/myofibroblasts, bile duct cells, and macrophages.

Adult↗
PubMed2000

Biliary atresia. A surgical perspective.

The combination of portoenterostomy with subsequent liver transplantation is the treatment of choice for patients with biliary atresia. It is important, however, to attempt to keep the patient's own organ by continuing efforts to achieve the best possible results with portoenterostomy. Additional basic research, perhaps concerning on the role of cytokines and apoptosis in the control of biliary atresia, may provide insight into possible new medical strategies for treating patients with biliary atresia. For example, in addition to portoenterostomy, control of apoptosis at various cellular levels and of bile duct cell proliferation and maturation by manipulation of the growth factors and cytokines may become part of future treatment modalities. Another direction of research should be the control of fibrogenesis, which might be accomplished by blocking TGF-beta 1 and platelet-derived growth factor and by HGF gene therapy. The author's current strategy for surgical treatment for patients with biliary atresia include (1) early diagnosis, including prenatal diagnosis and broader use of mass screening programs, (2) hepatic portoenterostomy, without stoma formation; (3) close postoperative care, especially for prevention of postoperative cholangitis; (4) revision of portoenterostomy only in selected cases; (5) early liver transplantation in patients with absolutely failed portoenterostomy; (6) avoidance of laparotomy for the treatment of esophageal varices and hypersplenism; (7) consideration of exploratory laparotomy or primary liver transplantation for patients with advanced liver disease at the time of referral. The development of new treatment modalities based on the understanding of the pathogenesis of the disease, and especially on the biology of intrahepatic bile ducts and hepatic fibrosis, is essential.

Biliary Atresia↗
PubMed2000

Intrahepatic mast cell population correlates with clinical outcome in biliary atresia.

PURPOSE: To determine if mast cells influence the clinical outcome in biliary atresia (BA), the authors examined the intrahepatic mast cell population in BA. METHODS: Mast cells were identified histochemically using Toludin Blue and immunohistochemically using antimast cell tryptase antibody in formalin-fixed paraffin-embedded sections from 21 cases of BA. Patients were divided into 3 groups; group I (n = 8) with good liver function, group II (n = 8) with moderate liver dysfunction, and group III (n = 5) with severe liver dysfunction. Liver biopsies from patients with choledochal cysts (CDC, n = 5), and normal liver (NL, n = 4) served as controls. The results were compared among the groups. RESULTS: Both histochemical and immunohistochemical methods showed similar data. Mast cells were seen mostly in the portal tracts. Mast cell numbers per medium power field (20 x magnification) were higher in BA than in the controls (15. 03 +/- 2.25 v 3.85 +/-.65, [mean +/- SEM], P <.05, BA v CDC; 15.03 +/- 2.25 v 1.73 +/-.06, [mean +/- SEM], P <.05, BA v NL, immunohistochemical data). Clinical correlation showed an association between higher mast cell number and liver dysfunction (32.62 +/-.80 v 8.52 +/-.87 [mean +/- SEM], group III v group I; P <. 05, immunohistochemical data). CONCLUSION: Increased mast cell population in BA adversely affects liver function and raises the possibility that type I allergic reaction may play role in the pathology of BA.

Biliary Atresia↗