Search PubMed⌕ Search

Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 541 records · Page 30Linked to original sources
PubMed1996

Postnatal development of adrenergic terminals in rat locus coeruleus, with special reference to growth of noradrenergic neurons.

The postnatal development of noradrenergic (NA) neurons and adrenergic (AD) terminals in the rat locus coeruleus (LC) was studied immunohistochemically. Cell body size was measured after staining of NA neurons with anti-tyrosine hydroxylase (TH) serum, and AD terminals were visualized with anti-phenylethanolamine N-methyltransferase serum. NA neurons in the LC were strongly TH-immunoreactive throughout the postnatal period. At birth, their mean cell body volume was 660 +/- 30 microns 3. It reached a maximum of 2580 +/- 230 microns 3 at postnatal day (PD) 14, and decreased thereafter to 930 +/- 50 microns 3 at PD 60. This transient enlargement of NA neurons may be closely related to the development of the cerebral cortex. AD afferents to the LC had terminals forming predominantly asymmetric junctions at birth (about 96% of all junctions). They occasionally made axo-somatic contact, suggesting that AD input already modulated the activity of LC neurons at this stage. AD terminals making axo-spinous synapses increased in number until PD 31, but still represented a minor proportion of these LC terminals, since there were more than 80% in contact with dendritic shafts at all ages examined.

Animals↗
PubMed1996

Restriction of substrate specificity of subtilisin E by introduction of a side chain into a conserved glycine residue.

Substitution of the conserved Gly127 for residues having a side chain markedly changed the substrate specificity of subtilisin E from Bacillus subtilis. The crystallographic findings suggested that Gly127 is responsible for accepting even the large P1 substrates, and the marked change of specificity was attributed to the introduction of a side chain in this position. To test this hypothesis, Gly127 was replaced with 3 non-charged amino acids, Ala, Ser and Val. When assayed with synthetic peptide substrates, all mutants purified from the periplasmic space in Escherichia coli showed a marked preference for small P1 substrate up to 150-fold relative to the wild-type. The kinetic data and molecular modeling analysis suggest that large hydrophobic P1 residues were unable to access the binding pocket due to steric hindrance.

Amino Acid Sequence↗
PubMed1996

Yeast HOG1 MAP kinase cascade is regulated by a multistep phosphorelay mechanism in the SLN1-YPD1-SSK1 "two-component" osmosensor.

An osmosensing mechanism in the budding yeast (Saccharomyces cerevisiae) involves both a two-component signal transducer (Sln1p, Ypd1p and Ssk1p) and a MAP kinase cascade (Ssk2p/Ssk22p, Pbs2p, and Hog1p). The transmembrane protein Sln1p contains an extracellular sensor domain and cytoplasmic histidine kinase and receiver domains, whereas the cytoplasmic protein Ssk1p contains a receiver domain. Ypd1p binds to both Sln1p and Ssk1p and mediates the multistep phosphotransfer reaction (phosphorelay). This phosphorelay system is initiated by the autophosphorylation of Sln1p at His576. This phosphate is then sequentially transferred to Sln1p-Asp-1144, then to Ypd1p-His64, and finally to Ssk1p-Asp554. We propose that the multistep phosphorelay mechanism is a universal signal transduction apparatus utilized both in prokaryotes and eukaryotes.

Amino Acid Sequence↗
PubMed1996

Structural organization and chromosomal assignment of the mouse embryonic TEA domain-containing factor (ETF) gene.

Embryonic TEA domain-containing factor (ETF) belongs to the family of proteins structurally related to transcriptional enhancer factor-1 (TEF-1) and is implicated in neural development. Isolation and characterization of the cosmid clones encoding the mouse ETF gene (Etdf) revealed that Etdf spans approximately 17.9 kb and consists of 12 exons. The exon-intron structure of Etdf closely resembles that of the Drosophila scalloped gene, indicating that these genes may have evolved from a common ancestor. The multiple transcription initiation sites revealed by S1 protection and primer extension analyses are consistent with the absence of the canonical TATA and CAAT boxes in the 5'-flanking region, which contains many potential regulatory sequences, such as the E-box, N-box, Sp1 element, GATA-1 element, TAATGARAT element, and B2 short interspersed element (SINE) as well as several direct and inverted repeat sequences. The Etdf locus was assigned to the proximal region of mouse chromosome 7 using fluorescence in situ hybridization and linkage mapping analyses. These results provide the molecular basis for studying the regulation, in vivo function, and evolution of Etdf.

Amino Acid Sequence↗
PubMed1996

Immunoelectron microscopic study on neuropeptide Y in the periodontal ligament of the incisor following peripheral nerve injury to the inferior alveolar nerve in the rat.

Immunoelectron microscopic analysis was carried out to examine whether neuropeptide Y (NPY)-like immunoreactivity (-LI) is localized in mechanoreceptors in the lingual periodontal ligament of the rat incisor following peripheral nerve injury to the inferior alveolar nerve (IAN). In the lingual periodontal ligament of normal animals, no NPY-like immunoreactive (-IR) primary afferents were observed, except for a very few sympathetic perivascular nerve fibers which showed NPY-LI. Fourteen days following chronic constriction injury to the IAN combined with sympathectomy of the superior cervical ganglion, thick NPY-IR nerve fibers showing tree-like raminifications were detected in the shear zone between the tooth-related part and alveolus-related part as well as in the alveolus-related part. Immunoelectron microscopy revealed that expanded NPY-IR nerve terminals were covered with several Schwann sheaths and that a part of the axoplasm expanded to the surrounding tissues. These ultrastructural features of NPY-IR structures were identical to those of periodontal Ruffini endings, categorized as slowly adapting mechanoreceptors. Thick (6-8 microns in diameter) NPY-IR axons were also observed without any apparent myelin sheath. The present results provide further evidence that NPY is closely associated with thick axons, probably myelinated nerves and Ruffini endings, following peripheral nerve injury.

Animals↗
PubMed1996

Neuropeptide Y-like immunoreactive primary afferents in the periodontal tissues following dental injury in the rat.

The distribution of neuropeptide Y (NPY)-like immunoreactive (-IR) nerve fibers in the periodontal tissues following dental injury to the rat maxillary first molar was examined with a combination of dental injury and surgical sympathectomy of the superior cervical ganglion (SCGx). In normal animals, NPY-IR nerve fibers were observed around the blood vessels of the trigeminal ganglion, dental pulp and periodontal tissues. These nerve fibers completely disappeared following SCGx. Fourteen days following dental injury of the maxillary first molar combined with SCGx, a small number NPY-IR cells was observed in the dorsal to middle portion of the maxillary division of the trigeminal ganglion. These were mostly medium- to large-sized cells with a mean +/- SD cross-sectional area of 541.4 +/- 239.3 microns 2. Approx. 50% of these cells had the cross-sectional areas between 400-600 micron 2. In the periodontal tissues of injured first molar, thick NPY-IR nerve fibers showing an irregular appearance were detected in the apical region. Immunoelectron microscopy showed that most NPY-IR nerve fibers near the lower half of the injured periodontal ligament had an axonal diameter of approx. 7-8 microns, and lacked apparent myelin sheaths. Near NPY-IR nerve fibers, many macrophages with phagosomes containing debris of the myelin sheaths were observed. At the oral epithelium covering the injured roots of the maxillary first molar, thick NPY-IR nerve fibers were recognizable and some penetrated the epithelium. No NPY-IR nerve fibers were observed in the dental pulp or periodontal tissues in second and third molars, and ultrastructural views of nerve fibers were almost intact following combined SCGx and dental injury to the first molar. The present results indicate that NPY-IR primary afferents appeared in the periodontal tissues following dental injury, and that NPY may be closely associated with the regeneration process of injured primary afferents.

Animals↗
PubMed1996

Galanin inhibits long-term potentiation at Schaffer collateral-CA1 synapses in guinea-pig hippocampal slices.

The role of galanin on long-term potentiation (LTP) of the field excitatory postsynaptic potentials (fEPSPs) at Schaffer collateral-CA1 synapses was investigated in guinea-pig hippocampal slices. Application of galanin (10(-7) M) inhibited the magnitude of LTP without any changes in the amplitude of fEPSP prior to tetanic stimulation. A putative central nervous system (CNS) type galanin receptor antagonist, galanin(1-13)-Pro-Pro-(Ala-Leu)2-Ala-Amide (M40), did not modify the magnitude of LTP when applied alone. However, M40 significantly reversed the inhibition by galanin when applied with galanin simultaneously. These findings suggest that galanin plays an inhibitory role through the CNS type galanin receptors.

Animals↗
PubMed1996

Factors correlated with portal venous invasion by hepatocellular carcinoma: univariate and multivariate analyses of 232 resected cases without preoperative treatments.

BACKGROUND: The postoperative intrahepatic recurrence of hepatocellular carcinoma (HCC) is high. It is difficult to distinguish whether the recurrence is metastatic or new primary lesion. To determine the malignant potential of HCC itself, we analyzed the risk factors associated with portal venous invasion since this is direct evidence of tumor invasiveness. METHODS: Two hundred and thirty-two patients who underwent curative hepatectomy for HCC without preoperative treatments were included in this study, because preoperative treatment caused the tumor to undergo a variety of histologic change. We analyzed the risk factors linked to portal venous invasion by both univariate and multivariate analyses. RESULTS: In an univariate analysis, tumors larger than 3 cm, high histologic grade (III or IV), the presence of fibrous capsule, necrosis, mitotic rate of more than 4/10 high power fields, peliotic change, presence of tumor giant cells, high platelet count, low level of indocyanine green retention rate at 15 minutes, and the absence of cirrhosis were significantly correlated with portal venous invasion. In multiple stepwise logistic regression analysis, tumors larger than 3 cm, high histologic grades, and the presence of fibrous capsule were strong predictors of portal venous invasion by HCC. CONCLUSIONS: Because the blood vessels of the fibrous capsule were frequently invaded by cancer cells, it may have been possible to prevent postoperative metastatic recurrence if HCC were resected before becoming large enough to have a fibrous capsule.

Adult↗
PubMed1996

Increase of p75 immunoreactivity in rat urinary bladder following inflammation.

Previous studies suggest that NGF may function as a mediator of inflammatory pain. Here, we examined the effect of inflammation on expression of the low affinity neurotrophin receptor p75, using the model of cyclophosphamide-induced cystitis in rats. In control rats, p75-positive thick fibre bundles were scattered in the muscle layer. At 2 and 3 days after injection of cyclophosphamide, numbers of p75-positive fine fibres in the muscle layer were dramatically increased. Electron microscopy revealed that p75 immunoreactivity was localized on the surface of Schwann cells and at the sites where they were apposed to axons. Results show that p75 is up-regulated in inflamed tissues, suggesting that p75 may bind to and take up nerve growth factor (NGF), thus participating in NGF-induced hyperalgesia.

Animals↗
PubMed1996

G protein-gated K+ channel (GIRK1) protein is expressed presynaptically in the paraventricular nucleus of the hypothalamus.

We prepared a specific antibody against GIRK1, the major subunit of the G protein-gated K+ (KG) channel. Immunohistochemical study revealed that GIRK1 immunoreactivity was detected in the presynaptic, but not in the postsynaptic, region in the paraventricular nucleus of the rat hypothalamus (PVN). Therefore, activation of the KG channel may underlie presynaptic inhibition of neurotransmitter release by various agonists, such as dopamine, noradrenaline, opioids, and histamine, in PVN.

Adenosine↗
PubMed1996

Spindle cell hepatocellular carcinoma. A clinicopathologic and immunohistochemical analysis of 15 cases.

BACKGROUND: Spindle cell hepatocellular carcinoma (SpHCC) has rarely been reported, and its clinicopathologic characteristics, histogenesis, and prognosis after hepatic resection have yet to be clarified. METHODS: Fifteen cases of SpHCC, including 13 surgically resected patients and 2 autopsy cases, were studied clinicopathologically and immunohistochemically. RESULTS: In 13 resected patients, all except 1 were male and the serum alpha-fetoprotein (AFP) was positive in 6 (46%). Portal venous invasion and intrahepatic metastases were frequent. In an immunohistochemical analysis of 13 SpHCC tumors, cytokeratin CAM 5.2 and AFP were positive in 8 (62%) tumors and 3 (23%) tumors in both ordinary HCC and spindle cell components, respectively. The spindle cell components, but not ordinary HCC components, revealed a positive reaction for vimentin in 8 (62%) tumors, S-100 protein and HAM-56 in 3 (23%) tumors, HHF-35 in 2 (15%) tumors, and alpha-smooth muscle actin, desmin, and KP-1 in 1 (8%) tumor, respectively. p53 overexpression was found in two SpHCC tumors. The survival curve after hepatic resection in the 13 patients with SpHCC was significantly worse than that of the 371 patients with Stage II-IV ordinary HCC (P < 0.001). CONCLUSIONS: These results suggest that SpHCC represents a sarcomatous transformation of HCC. The spindle cell components revealed an immunohistochemical expression of several markers of mesenchymal cells. In addition, poor survival after hepatic resection was documented.

Adult↗
PubMed1996

Results of 280 liver resections for hepatocellular carcinoma.

OBJECTIVE: To evaluate the recent results of liver resection in patients with hepatocellular carcinoma. DESIGN: Retrospective study. SETTING: A university hospital in Japan. PATIENTS: Two hundred eighty patients who underwent liver resection with complete extirpation of hepatocellular carcinoma from 1985 to 1993. MAIN OUTCOME MEASURES: Morbidity and survival after operation and the pathologic features of hepatocellular carcinoma according to the TNM classification of the International Union Against Cancer. RESULTS: More than 40% of the patients with stages I and II disease underwent a partial resection of the liver, whereas 50% of those with stages III and IVA were operated on with more than a bisegmentectomy. Fifty percent of all patients had no postoperative complications. The morbidities included intra-abdominal abscess (7%), bile leakage (5%), and hepatic failure (4%, of whom half died; mortality rate, 2%). Histopathologically, 32% of the stage I tumors were well differentiated (grade 1), while, in stage III, 56% had portal invasion and 61% had daughter lesions in the liver. The cumulative survival rates of patients with stages I, II, and III disease and all patients at 5 years were 69%, 52%, 32%, and 50%, respectively, while the disease-free survival rates at 5 years were 38%, 34%, 17%, and 29%, respectively. CONCLUSION: The recent results of liver resection for hepatocellular carcinoma are generally satisfactory; however, the recurrence rate is still high.

Aged↗
PubMed1996

Postoperative recurrence of solitary small hepatocellular carcinoma.

The prognosis of hepatocellular carcinoma after hepatic resection remains poor. The major cause is postoperative recurrence, most frequently intrahepatic. During the past 7 years, we conducted a detailed study of recurrence after hepatectomy in 34 patients with solitary small hepatocellular carcinoma measuring no larger than 4 cm in diameter, in which 13 cases had postoperative recurrent tumors, and two cases were considered multicentric. Eighty-five percent of recurrences were diagnosed at 6-18 months after the operation. The cumulative recurrence rates were 61% at 5 years after operation. When analyzing the factors affecting recurrence, a significant difference was observed regarding tumor diameter. After recurrence, most patients underwent percutaneous ethanol injection treatment and/or transcatheter arterial chemoembolization and lipiodolization. Four patients died of progressive disease within 1 year after recurrence; the treatment thus seemed to have no effect. The other patients with recurrence remain alive with the disease. The overall cumulative survival rates in this series were 76% at 3 years and 60% at 5 years after operation. To obtain better results after hepatectomy, even for small hepatocellular carcinoma, careful, long-term follow-up evaluation is therefore necessary for the multidisciplinary treatment of the postoperative recurrence, as well as the early diagnosis of tumors in high-risk patients.

Adult↗
PubMed1996

Adherence of synovial cells on EDA-containing fibronectin.

OBJECTIVE: To investigate the role of EDA-containing fibronectin (EDA+ FN), a splice variant of FN detectable in association with cellular transformation, in the adherence of synovial cells (SC) on rheumatoid cartilage surface. METHODS: The number of SC adherent on cartilage slices or on culture plates containing either EDA+ FN or plasma FN (pFN) was enumerated under a phase-contrast microscope. The portion of the FN molecule responsible for adherence of SC onto EDA+ FN was investigated by inhibition studies using antibodies or peptide fragments. RESULTS: SC adhered more strongly on the surfaces containing EDA+ FN than on those containing pFN (P < 0.01). When monoclonal antibodies against the EDA or the carboxyl-terminal heparin-binding (Hep2) domains were used, adhesion of SC onto EDA+ FN was reduced to a level comparable with that onto pFN. FN fragments containing Hep2 or heparan sulfate inhibited the adhesion of SC onto EDA+ FN. Treatment of SC with heparitinase, but not heparinase, reduced the adhesion of SC onto EDA+ FN. CONCLUSION: EDA+ FN enhances adherence of SC on the matrix via the Hep2 region of EDA+ FN.

Alternative Splicing↗
PubMed1996

Electron-microscopic study of dopaminergic structures in the medial subdivision of the monkey nucleus accumbens.

The medial subdivision of the monkey nucleus accumbens (NAC) is rich in dopamine (DA) and peptides. In the present investigation the mode of DA transmission in the medial subdivision was studied morphologically by light- and electron-microscopic immunocytochemistry using a monoclonal antibody raised against dopamine. The medial subdivision showed extremely dense accumulation of thick DA-immunoreactive varicose fibers. Electron-microscopic observation of single sections revealed that DA afferents had a relatively high incidence (33.2%) of asymmetric junctions in this area. Approximately 50% of the targets were dendritic shafts, 44.2% dendritic spines, and 5.1% somata. Some DA axons showed terminal profiles en passant within the synaptic complex, some of which showed synaptic triads. The unique ultrastructural features of DA terminals in the medial NAC indicate the existence of specific styles of DA transmission in the limbic structure.

Animals↗
PubMed1996

Immunoreactivity of antimitochondrial autoantibodies in Japanese patients with primary biliary cirrhosis.

The incidence and prevalence of primary biliary cirrhosis show wide geographic differences. The frequency of this disease in Japan is lower than in Northern Europe. To elucidate the immunoreactivity of serum with enzymes of the 2-oxo-acid dehydrogenase complex (2-OADC) and the M2 mitochondrial antigenic complex in Japanese patients, we examined sera from 107 patients with primary biliary cirrhosis from three geographically different regions of Japan. The sera were assayed by immunofluorescence on frozen tissue sections, immunoblotting on bovine heart mitochondria and recombinant E2 subunit of branched chain oxo-acid dehydrogenase complex (BCOADC-E2), ELISA using recombinant E2 subunit of human pyruvate dehydrogenase complex (PDC-E2) and purified porcine 2-oxoglutarate dehydrogenase complex (OGDC), and enzyme inhibition assay using procine PDC and OGDC. Of the 107 sera, 95 (88%) reacted by immunofluorescence, 102 (95%) by immunoblotting with at least one of the M2 autoantigens, although only 78 (73%) reacted with PDC-E2; 72 (67%) by ELISA with PDC-E2; and 81 (76%) with PDC by the enzyme inhibition assay. Thus, the frequency of reactivity with PDC-E2 by all assays was lower for Japanese than the reported frequency for Caucasian patients with primary biliary cirrhosis, whereas the frequency of reactivity by immunoblotting and ELISA against 2-OADC enzymes other than PDC was relatively higher. The relative frequency of reactivity of autoantibodies to the M2 autoantigens was similar for the three different regions of Japan. The different autoantibody profiles for Japanese and Caucasian patients with primary biliary cirrhosis point to immunogenetic and environmental determinants of this disease, which should provide new insights into its autoimmune origins.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1996

Intraventricular administration of estradiol modulates rat prolactin secretion and synthesis.

The effect of estradiol (E2) on rat tuberoinfundibular dopaminergic (TIDA) neurons was examined in vivo, employing chronic intraventricular (i.c.v.) infusion technique using an osmotic mini-pump. The activity of TIDA neurons was assessed by the release and synthesis of prolactin (PRL) in the rat pituitary gland and by the changes in the 3, 4-dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) levels and in the DOPAC/DA ratio in the rat hypothalamus. We also examined the [3H] E2 binding in the rat hypothalamus. Ovariectomized female Wistar rats with E2 replacement were treated with daily i.c.v. infusion of 1 microM of E2 or saline vehicle for 1, 3, and 7 days using the Alzet osmotic mini-pump and brain infusion kit. At 1 day of i.c.v. infusion of E2, the serum PRL level was significantly decreased compared with that in the vehicle group. Northern blot analysis of the total RNA isolated from the pituitary glands demonstrated a decrease in the PRL gene transcript level in the E2 group. At 3 days of E2 treatment, however, the serum PRL level was significantly increased compared with that of the vehicle-injected group and Northern blot analysis also demonstrated that the PRL gene transcript level was increased in the E2 group. At 7 days of E2 administration, there were no significant differences between the E2 and vehicle groups in either serum PRL or PRL gene transcript levels. There was a significant increase in the DOPAC/DA ratio after 1 day in the E2 group. However, no significant effects of E2 on this ratio were observed at 3 and 7 days of treatment. The DOPAC concentration in the E2 group was significantly increased at day 1 and significantly decreased at day 3, compared with that of the respective time in vehicle group. At day 7 there was no significant change in DOPAC concentration in either groups. The DA concentrations in the hypothalamus was not changed on any day in either group. Specific [3H] E2 binding was observed in the rat hypothalamus. These data suggest that E2 may have a biphasic effect on the accumulation of PRL gene transcripts and on the PRL secretion in the rat pituitary by first stimulating and then inhibiting the TIDA neuronal activity.

3,4-Dihydroxyphenylacetic Acid↗