Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 163 records · Page 9Linked to original sources

PubMed2000

Immunohistochemical detection of heme oxygenase-2 in the periodontal Ruffini ending of the rat incisor.

The present study was carried out to examine the occurrence of heme oxygenase-2 (HO-2) in the periodontal ligament of the rat incisor. HO-2-like immunoreactive (-IR) structures showed dendritic profiles, resembling the Ruffini endings, in the alveolar half of the ligament of rat incisor. Neither thin nerve fibers nor perivascular nerve fibers displayed HO-2-like immunoreactivity (-LI). No non-neural elements exhibited HO-2-LI. Electron microscopy revealed that immunoreactions were diffusely observed in the axon terminals of the Ruffini endings, but neither terminal Schwann cells nor Schwann sheaths contained immunoreactions for HO-2. Both most neurons in the trigeminal ganglion and trigeminal mesencephalic nucleus showed HO-2-LI. The presence of HO-2 in the periodontal Ruffini endings and its absence in the periodontal thin nerve fibers suggest the involvement of carbon monoxide produced by HO-2 in mechanoreception in the periodontal ligament.

Animals↗

PubMed2000

beta3-endonexin as a novel inhibitor of cyclin A-associated kinase.

Cyclin A is indispensable for S phase cell cycle progression and is suggested to be a crucial target of cell adhesion signals. In this study, we demonstrate that beta3-endonexin, a molecule known to associate with the integrin beta3 cytoplasmic domain, specifically binds cyclin A. Deletion of the amino-terminal 52-amino-acid residues including the cyclin-binding RxL motif abolishes the ability of beta3-endonexin to interact with cyclin A. In an in vitro kinase assay, beta3-endonexin inhibits pRB kinase activity associated with cyclin A-Cdk2 while leaving its histone H1 kinase activity unaffected. Coexpression of beta3-endonexin in yeast cells overcomes growth suppression caused by an activation of cyclin A-associated kinase. Our results indicate that beta3-endonexin is a novel cyclin A-binding molecule that regulates cyclin A-associated pRB kinase activity.

Animals↗

PubMed2000

p75-mediated neuroprotection by NGF against glutamate cytotoxicity in cortical cultures.

Accumulating evidence suggests that the neurotrophin receptors, Trks and p75, play distinct roles in regulating cells survival and death, with Trks important for cell survival, and p75 acting to induce cell death. Here, we provide evidence that, in neuronal cultures from rat cerebral cortex, nerve growth factor (NGF) exerts neuroprotective actions via p75. Incubating cultures with NGF for 1-24 h protected cortical neurons from delayed cytotoxicity induced by brief exposure to glutamate. Delayed neurotoxicity induced by a calcium ionophore, ionomycin, or nitric oxide (NO) donors such as S-nitrosocysteine (SNOC) and 3-morpholinosydnonimine (SIN-1), was also attenuated by pretreatment with NGF. RT-PCR analysis revealed the presence of p75 and trkB transcripts in cortical cultures, but did not detect transcripts of trkA, a high-affinity receptor for NGF. Brain-derived neurotrophic factor (BDNF), but not NGF, induced tyrosine phosphorylation of Trks, indicating that NGF does not activate Trks in cortical neurons. Concurrent application of anti-p75 neutralizing antibody markedly reduced the neuroprotective effect of NGF, but resulted in only a modest reduction of that of BDNF. BDNF-induced neuroprotection, but not NGF-induced neuroprotection, was inhibited by a protein synthesis inhibitor cycloheximide. Distinct signaling pathways mobilized by NGF and BDNF were also revealed in that NGF but not BDNF stimulated significant production of ceramides, whereas BDNF but not NGF caused persistent activation of mitogen-activated protein kinases. These results indicate that, although NGF and BDNF both protect cortical neurons from excitotoxicity, the mechanisms involved in their effects are totally different. The present results are, to our knowledge, the first to demonstrate the principal involvement of p75 in cytoprotective actions of neurotrophins.

Animals↗

PubMed2000

Evaluation of diabetic neuropathy through the quantitation of cutaneous nerves.

The significance and usefulness of immunohistochemically quantitated cutaneous nerves in the evaluation of diabetic neuropathy was examined in biopsied skins of the calf from healthy subjects (n=12) and non-insulin dependent diabetic patients (n=32) with diabetic sensory neuropathy. Skin samples were immunostained with antibodies against protein gene product (PGP) 9.5, a pan-axonal marker. A quantitative analysis to determine nerve fiber (NF) number and nerve lengths (NLs) was performed on nerve fibers of the epidermis and the dermis and on nerves surrounding sweat glands. Nerve function tests were performed on the biopsied sites and erythrocyte aldose reductase level was determined by enzyme-linked immunosorbent assay. Numbers of epidermal NFs, NLs of epidermis and dermis and NL around sweat glands were significantly decreased in diabetic patients compared with control subjects (P<0.001, P<0.001, P<0.01, P<0.01, respectively). NL of epidermis showed a significant correlation with NL of dermis (P<0.01). Sural nerve conduction velocity was significantly correlated with NL of dermis (P10.8 (average in 555 diabetic patients) ng/mgHb) possessed a shorter NL of dermis NFs than those with lower AR level (<10.8) (P<0.05). These findings suggest that the quantitation of cutaneous nerves in biopsied skin samples provides important information about diabetic neuropathy and may improve the understanding of the pathophysiology of sensory nerve terminals in diabetic neuropathy.

Aldehyde Reductase↗

PubMed2000

Preparative two-dimensional gel electrophoresis with agarose gels in the first dimension for high molecular mass proteins.

A two-dimensional gel electrophoresis (2-DE) method that uses an agarose isoelectric focusing (IEF) gel in the first dimension (agarose 2-DE) was compared with an immobilized pH gradient 2-DE method (IPG-Dalt). The former method was shown to produce significant improvements in the 2-D electrophoretic separation of high molecular mass proteins larger than 150 kDa, up to 500 kDa, and to have a higher loading capacity, as much as 1.5 mg proteins in total for micropreparative runs. The extraction medium found best in this study for agarose 2-DE of mammal tissues was 6 M urea, 1 M thiourea, 0.5% 2-mercaptoethanol, protease inhibitor cocktail (Complete Mini EDTA-free), 1% Triton X-100 and 3% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Trichloroacetic acid (TCA) treatment of the agarose gel after IEF is to be carefully weighed beforehand, because some high molecular mass proteins were less likely to enter the second-dimensional polyacrylamide gel after TCA fixation, and proteins such as mouse skeletal muscle actin gave pseudospots in the agarose 2-DE patterns without TCA fixation. As a good compromise we suggest fixation of proteins in the agarose gel with TCA for one hour or less. The first-dimensional agarose IEF gel containing Pharmalyte as a carrier ampholyte was 180 mm in length and 2.5-4.8 mm in diameter. The gel diameter was shown to determine the loading capacity of the agarose 2-DE, and 1.5 mg liver proteins in total were successfully separated by the use of a 4.8 mm diameter agarose gel.

Animals↗

PubMed2000

Nitric oxide inhibition improved myocardial metabolism independent of tissue perfusion during ischemia but not during reperfusion.

Nitric oxide (NO) is one of the important regulators of cardiac metabolism and function as well as of tissue perfusion. Myocardial NO formation is increased during ischemia and reperfusion. We investigated the roles of endogenous NO in myocardial metabolism during ischemia and reperfusion independent of tissue perfusion changes. In an open-chest pig model, a bolus infusion of 20 mg/kg of N(G)-nitro l -arginine methyl ester (l -NAME), a NO synthase inhibitor, did not alter the regional myocardial perfusion compared with a control saline injection, as measured by colored microsphares. Using(31)P-nuclear magnetic resonance spectroscopy, we showed that the tissue levels of pH and adenosine triphosphate (ATP) but not those of creatine phosphate were significantly preserved in the l -NAME group compared with the placebo group during the subsequent 15-min regional ischemia. Thus, l -NAME reduced myocardial ATP utilization during ischemia, and the mechanism underlying these effects is independent of tissue perfusion changes. However, l -NAME did not accelerate the recovery of ATP levels following reperfusion, suggesting distinct roles of endogenous NO during reperfusion.

Animals↗

PubMed2000

Correlation of EEG, neuroimaging and histopathology in an epilepsy patient with diffuse cortical dysplasia.

The correlation between scalp EEG, intraoperative electrocorticogram, neuroimaging and histopathology was examined in an epileptic child with diffuse cortical dysplasia. The 6-year-old girl with moderate mental retardation had suffered from intractable complex partial and generalized epilepsies since the age of 2 years. MR images demonstrated unilateral large macrogyria/polymicrogyria and schizencephaly in the right occipital lobe. The epileptic focus was detected on the macrogyria by EEG and single photon emission tomography. However, the intraoperative electrocorticogram showed frequent spikes from the polymicrogyria and no paroxysmal activity in the macrogyria. The polymicrogyria and the macrogyric lesion were resected, using an image-guided system. The histological findings revealed that the macrogyria was covered with and separated by glial bundles. It has been reported that epileptogenicity is produced from abnormal neurons and their arrangement in cortical dysplasia; in this case, however, the major dysplastic lesion had no epileptogenicity; rather the focus might be in the polymicrogyria around the lesion.

Cerebral Cortex↗

PubMed2000

Transforming growth factor-beta 1 derived from biliary epithelial cells may attenuate alloantigen-specific immune responses.

Immune response to liver allografts may be different from that to other organ transplants since immunological manipulation easily attenuates immune-response to liver allografts. Numerous studies on the alloantigen-specific immune response have been carried out, however, the precise mechanisms involved in this attenuation are not clear yet. Here we suggest the attenuation of alloantigen-specific immune response by TGF-beta 1 derived from biliary epithelial cells. The transforming growth factor-beta 1 (TGF-beta 1) expression in rat liver was examined immunohistologically. Rat biliary epithelial cells (BEC) were purified from the perfused liver and added to allogeneic mixed lymphocyte reaction (allo-MLR) to assess their attenuating potential on allo-MLR and alloantigen-specific cytotoxic T lymphocyte (allo-CTL) induction. Immunohistological investigation revealed the expression of TGF-beta 1 in biliary epithelial cells. Both purified biliary epithelial cells and TGF-beta 1 attenuated allo-MLR and allo-CTL induction in a dose-dependent manner, and anti-TGF-beta 1 antibody partially relieved this attenuation. This study reveals that biliary epithelial cells, the major target cells of allo-antigen specific immune response, contain TGF-beta 1 and that they have a capacity to attenuate allo-MLR and allo-CTL induction.

Animals↗

PubMed2000

Intrahepatic portosystemic venous shunt associated with biliary atresia: case report.

We describe an infant with intrahepatic portosystemic venous shunt (IPSVS), which was detected by MR angiography. IPSVS is rare and its cause is disputed. However, with improvements in imaging the number of reports of IPSVS identified incidentally in patients without definite symptoms is increasing. The present case is the first associated with congenital biliary atresia and the youngest reported in the literature.

Biliary Atresia↗

PubMed2000

Angiomyolipoma arising in the thigh.

A 41-year-old man presented with an asymptomatic mass in the right medial thigh. Magnetic resonance imaging (MRI) revealed a well-demarcated, 10-cm mass in the right adductor muscles. The margins of the mass exhibited high signal intensity and the rest showed low or iso signal intensity on T1-weighted MR images. However, the high signal intensity was decreased on T2-weighted images with fat suppression. The central part of the tumor was of inhomogeneous high signal intensity on T2-weighted images; after Gd-DTPA injection it enhanced in homogeneously on T1-weighted images with fat suppression. On dynamic computed tomography (CT) in the arterial phase, there were strongly enhancing spotty areas in the tumor. At surgery, a yellow-whitish tumor was resected and a pathological diagnosis of angiomyolipoma (AML) in the thigh was made.

Adipose Tissue↗

PubMed2000

Recurrent idiopathic iridocyclitis after autologous peripheral blood stem-cell transplantation followed by G-CSF administration for acute lymphoblastic leukemia.

We describe a patient who experienced a recurrence of idiopathic iridocyclitis on day 12 after autologous peripheral blood stem-cell transplantation (auto-PBSCT) followed by G-CSF administration for acute lymphoblastic leukemia (ALL). Autologous SCT has been reported to be effective and safe in achieving dose intensification of chemotherapeutic drugs for the treatment of hematopoietic malignancies, but its therapeutic effect on autoimmune diseases is not definite. The findings from the present case suggest that auto-PBSCT followed by G-CSF administration for patients with a history of some kind of autoimmune disorders may induce exacerbation or recurrence of its symptoms after hematopoietic recovery.

Combined Modality Therapy↗

PubMed2000

Vitamin B6 phototoxicity induced by UVA radiation.

We have previously reported that pyridoxine shows UVA-induced cytotoxicity. Four other vitamin B6 compounds (pyridoxal, pyridoxamine, pyridoxal phosphate, and pyridoxamine phosphate) are metabolically more important in vivo than pyridoxine. These compounds were examined for UVA phototoxicity to cultured human fibroblasts. The cytotoxicity was measured by post-UVA irradiation colony-forming ability. All the B6 compounds except pyridoxal phosphate showed cytotoxicity. Pyridoxamine phosphate, which is the most important form of vitamin B6 in vivo, had the strongest cytotoxic effect. To examine the involvement of reactive oxygen species in the phototoxicity, we performed an electron spin resonance study using the spin trapping agent, 5,5-dimethyl-1-pyrroline N-oxide, and diethylenetriaminepentaacetic acid. We failed to detect radicals derived from vitamin B6. The cytotoxic effect remained in UVA-irradiated solutions for at least 30 min after the end of UVA irradiation. Hydrogen peroxide was produced in the solution, but the amount was not enough to cause cytotoxicity. In addition, the cells from xeroderma pigmentosum patients who belong to group A or C showed survival curves similar to those of normal fibroblasts. This suggests that cyclobutane pyrimidine dimers or 6-4 photoproducts of DNA were not involved in this damage. These findings suggest that UVA-induced vitamin B6 cytotoxicity is caused by toxic photoproducts resulting from irradiated vitamin B6.

Cell Line↗

PubMed2000

Responses of immunocompetent cells in the dental pulp to replantation during the regeneration process in rat molars.

Responses of immunocompetent cells to tooth replantation during the regeneration process of the dental pulp in rat molars were investigated by immunocytochemistry using antibodies to class II major histocompatibility complex (MHC) molecules (OX6 antibody), monocyte/macrophage lineage cells (ED1 antibody) and protein gene product 9.5 (PGP 9.5), as well as by histochemical reaction for periodic acid-Schiff (PAS). Tooth replantation caused an increase in both the number of OX6- and ED1-positive cells and their immunointensity in the replanted pulp, but almost all PGP 9.5-immunoreactive nerves diminished in the initial stages. By postoperative day 3, many OX6- and ED -immunopositive cells had accumulated along the pulp-dentin border to extend their cytoplasmic processes into the dentinal tubules in successful cases. Once reparative dentin formation had begun after postoperative day 7, OX6- and ED1-immmunopositive cells became scattered in the odontoblast layer, while reinnervation was found in the coronal pulp. The temporal appearance of these immunocompetent cells at the pulp-dentin border suggests their participation in odontoblast differentiation as well as in initial defense reactions during the pulpal regeneration process. On postoperative day 14, the replanted pulp showed three regeneration patterns: (1) reparative dentin, (2) bone-like tissue formation, and (3) an intermediate form between these. In all cases, PAS-reactive cells such as polymorphonuclear leukocytes (PML) and mesenchymal cells occurred in the pulp space. However, the prolonged stagnation of inflammatory cells was also discernible in the latter two cases. Thus, the findings on PAS reaction suggest that the migration of the dental follicle-derived cells into the pulp space and the subsequent total death of the proper pulpal cells are decisive factors for eliciting bone-like tissue formation in the replanted pulp.

Animals↗

PubMed2000

Adenosquamous carcinoma of the remnant stomach: report of a case.

We report herein the case of a 59-year-old man found to have adenosquamous carcinoma of the remnant stomach which demonstrated rapid progression. The patient was admitted to our hospital to undergo surgery for a papillary tumor of the remnant stomach. Total resection of the remnant stomach with lymph node dissection was performed, and pathological examination confirmed a diagnosis of adenosquamous carcinoma with invasion into the muscularis propria and lymph node metastasis around the perigastric areas. Multiple liver metastases were found 6 months after the operation, for which a right hepatectomy was performed with curative intent; however, he died 2 months later due to lymphangitis carcinomatosa of the lung.

Carcinoma, Adenosquamous↗

PubMed2000

Disinfection potential of electrolyzed solutions containing sodium chloride at low concentrations.

Electrolyzed products of sodium chloride solution were examined for their disinfection potential against hepatitis B virus (HBV) and human immunodeficiency virus (HIV) in vitro. Electrolysis of 0.05% NaCl in tap water was carried out for 45 min at room temperature using a 3 A electric current in separate wells installed with positive and negative electrodes. The electrolyzed products were obtained from the positive well. The oxidation reduction potential (ORP), pH and free chlorine content of the product were 1053 mV, pH 2.34 and 4.20 ppm, respectively. The products modified the antigenicity of the surface protein of HBV as well as the infectivity of HIV in time- and concentration-dependent manner. Although the inactivating potential was decreased by the addition of contaminating protein, recycling of the product or continuous addition of fresh product may restore the complete disinfection against bloodborne pathogens.

Acids↗

PubMed2000

A metalloprotease is common to swine, avian and bovine isolates of Staphylococcus hyicus.

Staphylococcus hyicus is considered to be an etiological agent of exudative epidermitis in young pigs, but is frequently isolated from chickens and cows. In the present study, the proteases of 58 S. hyicus isolates from pigs, chickens and cows were examined by skim milk agar plate culture, gelatinolytic zymogram and polymerase chain reaction (PCR). These isolates showed proteolytic activity on skim milk agar plate, but activity differed amongst the isolates. In the gelatinolytic zymogram, one main band was observed in all the porcine, avian and bovine isolates, while one to two other bands were recognized in some isolates. The formation of the main band was inhibited by EDTA, suggesting that this protease is a metalloprotease. When the Shp1 gene, which codes for one the metalloproteases of S. hyicus as reported previously, was examined by PCR, one band arising from an open reading frame (ORF) was detected in all of 58 isolates tested. In addition, upstream nucleotides containing the promoter region of Shp1 gene were amplified and sequenced. From these results, it seems likely that the metalloprotease is common to porcine, avian and bovine isolates of S. hyicus.

Animals↗

PubMed2000

C-type natriuretic peptide-like immunoreactivity in the rat inner ear.

C-type natriuretic peptide (CNP) is a member of the atrial natriuretic peptide family (ANP family). The family also includes ANP and brain natriuretic peptide (BNP). These peptides regulate the homeostasis of body fluid and blood pressure as a neuropeptide in the central nervous system as well as a cardiac hormone in the periphery. We have recently reported the expression of CNP mRNA in the inner ear. To assess the possible physiological role of CNP in the inner ear, we investigated the localization of CNP peptide in the rat inner ear by immunohistochemistry at the light and electron microscopic level. CNP-like immunoreactivity was widely distributed in the secretory and the neuronal portion of the inner ear, i.e. the spiral ligament, the dark cell region of the utriculus, the epithelium of the endolymphatic sac, the spiral ganglion cells and the vestibular ganglion cells. The results suggest that CNP may play a role in the homeostasis of the perilymph and endolymph and may also influence nerve activities in the inner ear.

Animals↗

PubMed2000

Studies on the genotype-phenotype relation in the hph-1 mouse mutant deficient in guanosine triphosphate (GTP) cyclohydrolase I activity.

The guanosine triphosphate (GTP) cyclohydrolase I (GTP-CHI) catalyses the rate-limiting step in the de novo synthesis of tetrahydrobiopterin, a cofactor of three aromatic amino acid hydroxylases, one of which is phenylalanine hydroxylase. The hph-1 mouse mutant deficient in GTP-CHI activity exhibits hyperphenylalaninemia which peculiarly disappears at 3 weeks of age, thus corresponding to the increase in liver GTP-CHI activity. The present gas chromatographic-mass spectrometric analysis of the phenylalanine and catecholamine metabolisms demonstrated the former metabolism to remain disturbed even in adult hph-1, which demonstrated a metabolic basis for sensitivity to the phenylalanine challenge in adult hph-1. A Northern blot analysis showed the hepatic GTP-CHI RNA expression in hph-1 at 2, 3 and 4 weeks of age to parallel the peculiar time course of the enzyme activity previously reported. No mutation was detected in either the coding region or the 5' flanking region (nt.-1 to -746) of the GTP-CHI gene of the hph-1. Further molecular genetic analyses are therefore required to elucidate the mechanism of the peculiar phenotype of hph-1.

Animals↗