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Biomedical subjects

T Miyano

Publications and source records attributed to T Miyano.

At least 19 recordsLinked to original sources
PubMed2000

Comparison of substrate specificities of Escherichia coli endonuclease III and its mouse homologue (mNTH1) using defined oligonucleotide substrates.

Escherichia coli endonuclease III (Endo III) and its eukaryotic homologues are major repair enzymes for pyrimidine lesions formed by reactive oxygen species and ionizing radiation. In the present study, the activities of Endo III and its mouse homologue (mNTH1) have been compared using defined oligonucleotide substrates containing a urea residue (UR), two cis-thymine glycol (TG) diastereoisomers, 5, 6-dihydrothymine (DHT), and 5-hydroxyuracil (HOU). The substrates were incubated with Endo III and mNTH1, and their activities were compared based on the product analysis by gel electrophoresis. Endo III recognized all base lesions tested, but the activity for DHT was extremely lower than other substrates. In contrast, albeit some preference of UR, mNTH1 showed essentially comparable activities for all substrates including DHT. Comparison of the enzymatic parameters for cis-TG and DHT revealed that large decreases in the affinity (K(m), 27-fold) and k(cat) (11-fold) relative to cis-TG made DHT an very poor substrate for Endo III. mNTH1 had comparable affinities and k(cat) for both cis-TG and DHT, though turnover (k(cat)) of mNTH1 was notably slower than Endo III. In view of the reaction mechanism, the paired base effect on the damage recognition by the two enzymes was also examined. The activities of Endo III for UR and HOU were paired base-independent, but those for cis-TG and DHT were significantly enhanced when paired with G. With mNTH1, the paired base effect was evident only for DHT. The variations of the repair activity with paired bases and enzymes are discussed in relation to the base flipping mechanism suggested for base excision repair enzymes.

Animals↗
PubMed2000

Specific regulation of CENP-E and kinetochores during meiosis I/meiosis II transition in pig oocytes.

To understand the mechanisms which regulate meiosis-specific cell cycle and chromosome distribution in mammalian oocytes, the level and the localization of CENP-E and the kinetochore number and direction on a half bivalent were examined during pig oocyte maturation. CENP-E is a kinetochore motor protein whose intracellular level and localization are strictly regulated in the somatic cell cycle. The localizations of CENP-E on meiotic chromosomes from diakinesis stage to anaphase I and at the spindle midzone at telophase I were shown by immunofluorescent confocal microscopy to be similar to those in somatic cells of pig and other species. Further, ultrastructural analysis revealed the presence of CENP-E on fibrous corona and outer plate of kinetochores of the meiotic chromosomes. However, unlike mitosis, CENP-E staining was continuously detected either at the spindle midzone or on the kinetochores of segregated chromosomes during the first polar body emission. Consistent with this, immunoblot analysis revealed that CENP-E level remained high during meiosis I/meiosis II (MI/MII) transition and that some of CENP-E survived through the transition even in cycloheximide-treated oocytes in which cyclin B1 was completely degraded. Furthermore, examinations of CENP-E signals in confocal microscopy and kinetochores in electron microscopy in MI and MII oocytes provide the cytological evidence in mammalian oocytes which suggests that each sister chromatid in a pair has its own kinetochore which localizes side-by-side so that two sister chromatids on a half bivalent are oriented toward and connected to the same pole in MI.

Animals↗
PubMed2000

Developmental regulation of effect of epidermal growth factor on porcine oocyte-cumulus cell complexes: nuclear maturation, expansion, and F-actin remodeling.

Epidermal growth factor (EGF) efficiently stimulates expansion of mouse and rat oocyte-cumulus complexes (OCC). Contradictory data have been published by several laboratories about the ability of EGF to stimulate expansion of porcine OCC. We assumed that these contradictions may have resulted from heterogeneous conditions used for isolation, culture, and assessment of OCC. The present experiments were designed to test the hypothesis that porcine OCC acquire the ability to synthesize hyaluronic acid (HA) and undergo expansion following EGF-stimulation gradually during the growth of follicles. For this reason, we isolated OCC from follicles of different sizes and assessed quantity of produced HA and proportions of expanding OCC after stimulation by EGF. In addition, we assessed in those OCC changes in morphology of cumulus cells and assembly of F-actin microfilaments, which are necessary for expansion to occur. Finally, nuclear maturation of EGF-stimulated OCC was assessed and its relationship with occurrence of expansion was evaluated. In all experiments, OCC stimulated with FSH were used as positive controls. The results showed that EGF did not stimulate production of HA, rearrangement of F-actin and expansion in OCC isolated from small follicles (<4 mm in diameter). OCC isolated from large preovulatory follicles (6-7 mm in diameter and PMSG-stimulated follicles) underwent efficient expansion when stimulated by EGF (93% and 100%, respectively). EGF dramatically stimulated total production of HA in these OCC and its retention in extracellular matrix of the expanding cumulus. Cumulus cells of the large OCC underwent essential changes of their morphology and extensive rearrangement of F-actin microfilaments following stimulation with EGF. Interestingly, EGF enhanced nuclear maturation of OCC isolated from both small and large follicles, which suggest diversity of signaling pathways controlling maturation and expansion. FSH caused cumulus expansion, F-actin remodeling, and enhancement of oocyte nuclear maturation in OCC originated from both small and large follicles. We conclude that EGF can stimulate expansion of porcine OCC in vitro; however, only of those isolated from large follicles. This indicates that EGF may have a physiological role in regulation of porcine cumulus expansion in preovulatory follicles, presumably as a mediator of signals elicited by the LH surge.

Actins↗
PubMed2000

alpha-Glutathione-s-transferase as a new sensitive marker of hepatocellular damage in biliary atresia.

Early identification of patients likely to deteriorate post-hepatic portoenterostomy for biliary atresia (BA) would be beneficial. alpha-Glutathione-s-transferase (alpha-GST) is a serologic marker of reactive hepatocellular damage because of its low molecular weight, uniform hepatic distribution, high cytosol concentration, and short half-life. We evaluated whether serum alpha-GST in post-surgical BA patients correlates with liver function (LF) and investigated its potential as a medium- to long-term marker of prognosis. Postoperative BA patients (n = 30; mean age: 11.8 +/- 3.7 years) were divided into three groups based on average LF over the 3 months prior to this study. Group I (n = 8) were jaundice-free and had normal LF. Group II (n = 12) had moderate liver dysfunction, and group III (n = 10) had severe liver dysfunction. Serum alpha-GST was determined using a specific ELISA. Tissue alpha-GST was determined immunohistochemically, using liver needle-biopsy specimens. Bile lakes were found in 5 group II patients and 5 group III patients. Serum alpha-GST was significantly higher in group II (20.7 +/- 8.4 ng/ml) than in groups I (4.7 +/- 1.3 ng/ml) and III (8.0 +/- 1.2 ng/ml) (P < 0.0001) and was highest in group II subjects with bile lakes. In control liver specimens alpha-GST distribution was weak but uniform throughout normal liver lobule hepatocytes. In group II there was strong staining in centrilobular hepatocytes, and in group III alpha-GST was only found in regenerative nodules. We conclude that alpha-GST may be a more sensitive indicator of hepatocellular damage in BA because its distribution is correlated to the proportion of functioning liver tissue present. This is the first report of this relationship, which has great implications for group II subjects because a sudden shift in concentration of alpha-GST may be a better predictor of impending hepatic dysfunction than conventional LF tests.

Adolescent↗
PubMed2000

Histology of the neobladder mucosa after sigmoidocolocystoplasty.

PURPOSE: The aim of this study was to examine the histopathology of neobladder mucosa biopsy specimens obtained routinely as part of postsigmoidocolocystoplasty (SCP) follow-up. METHODS: One hundred cases of SCP (mean age at surgery, 10.6 years) performed by the authors were examined for the presence of dysplasia or malignant changes in the mucosa of the neobladder using H&E and proliferating cell nuclear antigen (PCNA) staining. RESULTS: No dysplastic or malignant changes were identified in any case. Metaplasia was found in 5 cases and hyperplasia in 2. There were no major differences found on H&E and PCNA staining of specimens obtained after different periods of follow-up post-SCP; follow-up was short term (up to 5 years) in 44 cases, medium term (from 5 to 10 years) in 48 cases, and long term (over 10 years) in 8 cases. PCNA staining was significantly more intense in subjects who stopped regular bladder irrigations (BI) post-SCP and in subjects in whom bladder stones developed (P < .05; Welch's t test), compared with subjects who continued BI and subjects in whom bladder stones did not develop. CONCLUSIONS: After SCP, patients are advised to continue BI. Regular biopsies should be part of routine follow-up, especially in subjects with bladder stones.

Adolescent↗
PubMed2000

Pyloromyotomy versus atropine sulfate for infantile hypertrophic pyloric stenosis.

PURPOSE: Atropine sulfate (atropine) and pyloromyotomy were compared for managing infantile hypertrophic pyloric stenosis (IHPS). METHODS: From 1996 to 1998, cases of IHPS treated surgically (pyloromyotomy; n = 20) or medically (atropine; n = 14) at separate institutions were compared retrospectively with regard to status on presentation, physical symptoms and signs, progress, and costs. Atropine was given orally, then intravenously if ineffective. Refractory cases were referred for pyloromyotomy. RESULTS: All subjects were matched for clinical and physiological status on admission. Oral atropine alone was effective in 11 cases, was converted to intravenous atropine in 2 cases, and was terminated in 1 case because of hematemesis. Two cases were referred for pyloromyotomy. All pyloromyotomies were successful. Atropine took on average, 2.6 days to take effect. The difference in time taken for normalization of pyloric muscle thickness between the 2 groups was not significant. Average time to return to full feeding was longer in the atropine group (P<.01). Costs were lower in the atropine group (P<.01). There were 2 wound infections in the pyloromyotomy group, but no adverse effects of atropine. There were no recurrences in either group. CONCLUSION: This study provides reasonable evidence to support a trial of atropine in IHPS.

Adult↗
PubMed2000

Localisation of phosphorylated MAP kinase during the transition from meiosis I to meiosis II in pig oocytes.

Mitogen-activated protein kinase (MAPK) has been reported to be involved in oocyte maturation in all animals so far examined. In the present study we investigate the expression and localisation of active phosphorylated MAPKs (p44ERK1/p42ERK2) during maturation of pig oocytes. In immunoblot analysis using anti-p44ERK1 antibody which recognised both active and inactive forms of p44ERK1 and p42ERK2, we confirmed that MAPKs were phosphorylated around the time of germinal vesicle breakdown (GVBD) and the active phosphorylated MAPKs (pMAKs) were maintained until metaphase II, as has been reported. On immunofluorescent confocal microscopy using anti-pMAPK antibody which recognised only phosphorylated forms of MAPKs, pMAPK was localised at the spindle poles in pig mitotic cells. On the other hand, in pig oocytes, no signal was detected during GV stage. After GVBD, the area around condensed chromosomes was preferentially stained at metaphase I although whole cytoplasm was faintly stained. At early anaphase I, the polar regions of the meiotic spindle were prominently stained. However, during the progression of anaphase I and telophase I pMAPK was detected at the mid-zone of the elongated spindle, gradually becoming concentrated at the centre. Finally, at the time of emission of the first polar body, pMAPK was detected as a ring-like structure between the condensed chromosomes and the first polar body, and the staining was maintained even after the metaphase II spindle was formed. The inhibition of MAPK activity with the MAPK kinase inhibitor U0126 during the meiosis I/meiosis II transition suppressed chromosome separation, first polar body emission and formation of the metaphase II spindle. From these results, we propose that the spindle-associated pMAPKs play an important role in the events occurring during the meiosis I/meiosis II transition, such as chromosome separation, spindle elongation and cleavage furrow formation in pig oocytes.

Animals↗
PubMed2000

Degradation of pig cyclin B1 molecules precedes MAP kinase dephosphorylation during fertilisation of the oocytes.

Pig oocytes at metaphase II were activated by penetration of spermatozoa in cycloheximide-free and cycloheximide-containing fertilisation media. The precise nuclear stage, and the kinetics of degradation of cyclin B1 and dephosphorylation of MAP kinase were assessed after insemination. After maturation culture, 96% of oocytes reached metaphase II. At 6 h after insemination in cycloheximide-free medium, 68% of the oocytes were activated and had progressed to anaphase II or beyond. After 8 h, 89% of the oocytes were activated: a female pronucleus had formed and the heads of penetrating spermatozoa had enlarged and changed to male pronuclei. In the cycloheximide-containing medium, activation of oocytes started earlier than in cycloheximide-free medium. After 4 h, 43% of the oocytes were activated, and the percentage increased to 97% after 6 h. Pig cyclin B1 disappeared in the oocytes at 6 h after insemination in both cycloheximide-containing and cycloheximide-free media. Pig oocytes at metaphase II contained two types of MAP kinase--ERK 1 and ERK 2--in their active phosphorylated forms. At 8 h after insemination ERK 2 changed to the fast-migrating inactive form in the oocytes cultured in both cycloheximide-containing and cycloheximide-free media, although the shift-down was not complete. The change was delayed by 2 h after the degradation of cyclin B1 molecules. These results demonstrate that degradation of pig cyclin B1 molecules corresponds to the transition of the oocytes from metaphase II arrest to anaphase II/telophase II and was followed by MAP kinase dephosphorylation.

Animals↗
PubMed2000

Xanthogranulomatous pyelonephritis in childhood: a rare but important clinical entity.

PURPOSE: Xanthogranulomatous pyelonephritis (XGPN) is extremely rare in children. The authors review their experience of this condition. METHODS: Medical records were investigated to conduct a retrospective study of 4 patients with XGPN (3 boys, 1 girl; age range, 2 months to 7 years) at the authors' institute over the past 14 years. RESULTS: Three of the 4 patients presented with fever of unknown origin and 1 with general fatigue. An abdominal mass was palpable in two cases at initial presentation. Although all patients had pyuria or hematuria, preoperative urine culture was positive in only 2 cases. Preoperative radiologic studies showed that 1 kidney was affected completely in 2 cases and affected partially in 2 cases. Preoperatively, the provisional diagnosis was XGPN in 3 cases, and Wilms' tumor in 1 case. Total nephrectomy was performed in 3 cases and enucleation in 1 case. XGPN was confirmed in all cases by histopathologic studies, but the underlying disease could be identified only in 1 case (cystinuria). All patients did well postoperatively and have had no further health problems over a mean follow-up period of 4.8 years. CONCLUSIONS: XGPN should be considered when there is a history of recurrent or therapy-resistant pyelonephritis. Preoperative radiologic investigation is paramount for diagnosis, and nephrectomy is the treatment of choice, although partial resection or enucleation are adequate for partially affected kidneys.

Child↗
PubMed2000

Tubed latissimus dorsi musculocutaneous flaps for esophageal replacement in puppies: long-term follow-up.

PURPOSE: The aim of this study was to show that a tubed latissimus dorsi musculocutaneous flap (tubed LDMCF) may be useful for treating circumferential esophageal defects. METHODS: A segment of esophagus 3 vertebrae long was excised through a right thoracotomy in each of 6 puppies, and a tubed LDMCF was interposed between the cut ends of esophagus. The puppies were sacrificed after a mean follow-up period of 6.6 years. The tubed LDMCF was examined histologically. Functional integrity was assessed using barium meal and endoscopy before sacrifice. RESULTS: All puppies survived and grew normally on a normal diet, although 4 vomited occasionally. There was smooth passage of barium through the tubed LDMCF without stenosis, although endoscopy showed regrowth of hair. Histologically, no metaplasia, dysplasia, or malignancy was observed in any tubed LDMCF. CONCLUSIONS: The tubed LDMCF is technically safe, obviates the necessity for laparotomy, and long-term follow-up would suggest that it is histologically stable. Thus, it could become an alternative procedure for bridging esophageal defects.

Animals↗
PubMed2000

Idiopathic gastric perforation in neonates and abnormal distribution of intestinal pacemaker cells.

BACKGROUND/PURPOSE: The etiology of idiopathic gastric perforation (IGP) in neonates is unclear. Interstitial cells of Cajal (ICC) express tyrosine kinase receptor C-kit, and act as gastrointestinal pacemaker cells. Stem cell factor (SCF) is a C-kit ligand and plays an important role in immune system homeostasis in the gastrointestinal tract. The authors hypothesized that abnormal distribution of ICC or SCF in the gastric wall (ie, abnormal motility or impaired immunity) could predispose the stomach to IGP. METHODS: Stomachs obtained at postmortem from neonates who died of IGP (n = 7) and other causes (control group; n = 10) were used. Biopsy sections were taken at random from various sites in the stomach, including macroscopically intact areas, and labeled immunohistochemically using antibodies to C-kit(a marker for ICC) and SCF. RESULTS: In all control specimens, ICC were present between the muscle layers and around the myenteric plexuses of the stomach wall. In contrast, ICC were absent in all biopsy sections from 3 of the 7 IGP stomachs. In the remaining 4 IGP stomachs, there were fewer ICC in the muscle layers compared with controls, and ICC were absent around the myenteric plexuses. The distribution of SCF immunoreactivity in IGP and control specimens was similar. CONCLUSION: The findings suggest that a lack of ICC (ie, gastric hypomotility) may be implicated in the etiology of IGP in neonates.

Analysis of Variance↗
PubMed2000

Congenital biliary dilatation.

Congenital biliary dilatation is commonly associated with pancreaticobiliary malunion. Its etiology remains unknown. With the advent of accurate cholangiography, combined abnormalities of the intrahepatic duct, common channel, and pancreatic duct are being identified more frequently in patients with congenital biliary dilatation. Early diagnosis followed by cyst excision is the treatment of choice, even in asymptomatic cases. The treatment of intrahepatic and intrapancreatic ductal diseases such as intrahepatic duct dilatation and stone debris in the intrahepatic duct and common channel are also discussed. The value of intraoperative endoscopy as an adjunct to cyst excision for the prevention of postoperative complications is explained.

Bile Ducts, Intrahepatic↗
PubMed2000

Spindle formation and dynamics of gamma-tubulin and nuclear mitotic apparatus protein distribution during meiosis in pig and mouse oocytes.

This work focuses on the assembly and transformation of the spindle during the progression through the meiotic cell cycle. For this purpose, immunofluorescent confocal microscopy was used in comparative studies to determine the spatial distribution of alpha- and gamma-tubulin and nuclear mitotic apparatus protein (NuMA) from late G2 to the end of M phase in both meiosis and mitosis. In pig endothelial cells, consistent with previous reports, gamma-tubulin was localized at the centrosomes in both interphase and M phase, and NuMA was localized in the interphase nucleus and at mitotic spindle poles. During meiotic progression in pig oocytes, gamma-tubulin and NuMA were initially detected in a uniform distribution across the nucleus. In early diakinesis and just before germinal vesicle breakdown, microtubules were first detected around the periphery of the germinal vesicle and cell cortex. At late diakinesis, a mass of multi-arrayed microtubules was formed around chromosomes. In parallel, NuMA localization changed from an amorphous to a highly aggregated form in the vicinity of the chromosomes, but gamma-tubulin localization remained in an amorphous form surrounding the chromosomes. Then the NuMA foci moved away from the condensed chromosomes and aligned at both poles of a barrel-shaped metaphase I spindle while gamma-tubulin was localized along the spindle microtubules, suggesting that pig meiotic spindle poles are formed by the bundling of microtubules at the minus ends by NuMA. Interestingly, in mouse oocytes, the meiotic spindle pole was composed of several gamma-tubulin foci rather than NuMA. Further, nocodazole, an inhibitor of microtubule polymerization, induced disappearance of the pole staining of NuMA in pig metaphase II oocytes, whereas the mouse meiotic spindle pole has been reported to be resistant to the treatment. These results suggest that the nature of the meiotic spindle differs between species. The axis of the pig meiotic spindle rotated from a perpendicular to a parallel position relative to the cell surface during telophase I. Further, in contrast to the stable localization of NuMA and gamma-tubulin at the spindle poles in mitosis, NuMA and gamma-tubulin became relocalized to the spindle midzone during anaphase I and telophase I in pig oocytes. We postulate that in the centrosome-free meiotic spindle, NuMA aggregates the spindle microtubules at the midzone during anaphase and telophase and that the polarity of meiotic spindle microtubules might become inverted during spindle elongation.

Animals↗
PubMed2000

An annular pancreas derived from paired ventral pancreata, supporting Baldwin's hypothesis.

An annular pancreas is a rare malformation. It is generally accepted that the ring formation originates from a single ventral pancreas, as suggested by Lecco. No reports of resected and/or autopsied annular pancreata derived from paired ventral pancreata, thus supporting Baldwin's hypothesis, have been published. We describe an annular pancreas originating from paired ventral pancreata, thus supporting Baldwin's hypothesis, and attempt to clarify the pathogenesis of an annular pancreas. The patient was a 1-day-old Japanese male newborn, born at 32 weeks of pregnancy. He died from respiratory failure owing to esophageal atresia the next day. Autopsy incidentally revealed an annular pancreas that was examined histologically. Multiple 4 microm thick serial sections were obtained from paraffin-embedded pancreatic tissue. Sections for histologic analysis were subjected to hematoxylin-eosin staining and pancreatic polypeptide immunostaining. An unusually large pancreatic duct encircled by pancreatic tissue ran around the duodenum, and the duct was confirmed to flow into the major papilla. The islets of the encircling pancreas were positive for pancreatic polypeptide. A normal main and accessory pancreatic duct were also identified. Histologic and immunohistochemical evaluation revealed that the ring formation originated from the left lobe of paired ventral pancreata. An annular pancreas that was investigated histopathologically and immunohistochemically and found to support Baldwin's hypothesis is described.

Esophageal Atresia↗
PubMed2000

Intraoperative pancreatoscopy for pancreatic duct stone debris distal to the common channel in choledochal cyst.

BACKGROUND/PURPOSE: Pancreatic duct stone debris is a recognised problem in patients with choledochal cyst (CC). The authors present the use of intraoperative pancreatoscopy (IP) in diagnosis and treatment of pancreatic duct stone debris distal to the common channel (distal PDSD). METHODS: Sixty-seven patients with CC treated over the past 12 years were reviewed retrospectively. Distal PDSD was detected in 8 of these 67 cases (11.9%) using cholangiography. IP of the common channel or pancreatic duct at the time of surgery for CC was performed using a pediatric cystoscope in 7 of these 8 cases. RESULTS: All 8 patients had a long common channel. All presented with acute pancreatitis. In 7 of these 8 patients, IP was efficient in detecting and for removing distal PDSD by irrigation. In the remaining case associated with annular pancreas, distal PDSD was identified in the proximal pancreatic duct and was removed directly after incision of the pancreatic duct. Postoperative pancreatitis occurred in only 1 case. All patients are well after a mean follow-up period of 7.3 years. CONCLUSION: Distal PDSD should not be ignored. IP allows direct examination of the pancreatic duct system and facilitates complete removal of distal PDSD, which may be the cause of relapsing pancreatitis or pancreatolithiasis after radical surgery for CC.

Acute Disease↗