Biomedical subjects

M Inoue

Publications and source records attributed to M Inoue.

At least 127 records · Page 7Linked to original sources

PubMed2001

Targeting superoxide dismutase to renal proximal tubule cells inhibits mitochondrial injury and renal dysfunction inuduced by cisplatin.

We recently reported the synthesis of a cationic superoxide dismutase (SOD) derivative (AH-SOD) that rapidly and selectively accumulates in and around proximal tubule cells and effectively dismutes superoxide radicals in situ. The present study revealed that administration of cis-diamminedichloroplatinum(II)-elicited oxidative stress in renal mitochondria, decreased the renal expression of Bcl-x, released cytochrome c from mitochondria to cytosol, and induced apoptosis and renal dysfunction by a mechanism that was inhibited by AH-SOD. These results suggest that targeting SOD to proximal tubule cells protects renal function and permits the administration of fairly high doses of nephrotoxic anticancer agents, such as cisplatin, without causing renal injury.

Animals↗

PubMed2001

Somatic mutation of mitochondrial DNA in cancerous and noncancerous liver tissue in individuals with hepatocellular carcinoma.

Unlike other types of cancer, hepatocellular carcinoma (HCC) is usually preceded by chronic inflammation caused by viral infection. The mutation of mitochondrial DNA (mtDNA) in hepatocarcinogenesis associated with viral infection was investigated. Compared with control liver tissue, the frequency of mtDNA mutations was markedly increased in both noncancerous and cancerous liver specimens from individuals with HCC. The accumulation of mtDNA mutations in HCC tissue reflected the degree of malignancy. The frequency of mtDNA mutations in HCC tissue was also greater than that described previously for other types of tumors. These observations suggest that the repeated destruction and regeneration of liver tissue associated with chronic viral hepatitis lead to the accumulation of mtDNA mutations. The genetic instability that results in the high rate of mtDNA mutation in cancerous liver tissue is also consistent with the multicentric hepatocarcinogenesis detected clinically.

Carcinoma, Hepatocellular↗

PubMed2001

Novel functions of complex carbohydrates elucidated by the mutant mice of glycosyltransferase genes.

Complex carbohydrates consist of carbohydrate moieties and protein or lipid portions, resulting in the formation of glycoproteins, proteoglycans or glycosphingolipids. The polymorphic carbohydrate structures are believed to contain profound biological implications which are important in cell-cell or cell-extracellular matrix interactions. A number of studies to delineate the roles of carbohydrates have been performed, and demonstrated definite changes in their profiles, cellular phenotypic changes or, sometimes, morphological and functional changes in tissues after modification of their structures. Recent successes in the isolation of glycosyltransferase genes and their modification enzyme genes has enabled clearer demonstrations of the roles of complex carbohydrates. In particular, genetic modification of glycosyltransferase genes in mice can elucidate the biological significances of their products in vivo. Here, we summarize recent advances in the understanding of the roles of complex carbohydrates provided from studies of gene knock-out mice of glycosyltransferase and modification enzyme genes focusing on novel functions which had not been expected.

Animals↗

PubMed2001

Effects of slow repetitive transcranial magnetic stimulation on heart rate variability according to power spectrum analysis.

We examined whether repetitive transcranial magnetic stimulation (rTMS) at a low rate could influence autonomic function, specially heart rate variability (HRV) by power spectrum analysis. We studied 16 healthy male volunteers as a stimulation group and 16 others as a sham group. The stimulation group received magnetic stimulations from a circular coil over Cz at a frequency of 0.2 Hz and an intensity presenting 90% of the motor threshold. Experiments in both groups included four daily sessions; at each, a train of 70 stimuli was delivered over 350 s. HRV of low-frequency power (LF) in a standing position and high-frequency power (HF) in a supine position were measured before and after each session. After stimulation, HF and LF powers were significantly increased. After sham stimulation, the power of HF but not that of LF significantly increased. Neither actual nor sham stimulation produced a long-term effect detectable on day 5. The finding of transiently increased LF power following actual but not sham stimulation suggests that rTMS may activate the sympathetic nervous system.

Adult↗

PubMed2001

Low-threshold potassium channels and a low-threshold calcium channel regulate Ca2+ spike firing in the dendrites of cerebellar Purkinje neurons: a modeling study.

Various types of voltage-gated ion channels are distributed along the dendrites of neurons in the central nervous system. We have recently shown experimentally that the dendrites of cerebellar Purkinje neurons contain low-threshold voltage-gated Ca(2+) channels and low-threshold voltage-gated K+ channels. Although we found that these channels are involved in regulating the onset of Ca(2+)-dependent action potentials in the dendrites, we were unable to identify which of the known types of low-threshold Ca2+ channels and K+ channels were responsible, since there was no reliable method of discriminating between them. Here, we have built a detailed compartmental model of a Purkinje neuron by incorporating two types of low-threshold Ca2+ channel (T-type and class-E, or R-type) and two types of low-threshold K+ channel (A-type and D-type), in addition to another eight voltage-gated channel types, using a compartmental model neuron simulator. The model reproduces the basic features of the depolarization-induced responses of Purkinje neurons, such as fast Na+ spikes in the soma, Ca2+ spikes in the dendrites, the slow onset of Ca2+ spikes, repetitive Ca2+ spikes in the presence of TTX, the marked shortening of Ca2+ spike onset in the presence of 4-aminopydridine, and the longer Ca2+ spike onset in the presence of Ni2+. Our model shows that the D-type K+ channel and the class-E Ca2+ channel regulate the onset of depolarization-induced Ca2+ spikes in Purkinje neurons. These channels might be involved in integrating synaptic inputs in Purkinje neurons.

Action Potentials↗

PubMed2001

Antinociceptive effect produced by intracerebroventricularly administered dynorphin A is potentiated by p-hydroxymercuribenzoate or phosphoramidon in the mouse formalin test.

The antinociceptive effects of intracerebroventricularly (i.c.v.) administered dynorphin A, an endogenous agonist for kappa-opioid receptors, in combination with various protease inhibitors were examined using the mouse formalin test in order to clarify the nature of the proteases involved in the degradation of dynorphin A in the mouse brain. When administered i.c.v. 15 min before the injection of 2% formalin solution into the dorsal surface of a hindpaw, 1-4 nmol dynorphin A produced a dose-dependent reduction of the nociceptive behavioral response consisting of licking and biting of the injected paw during both the first (0-5 min) and second (10-30 min) phases. When co-administered with p-hydroxymercuribenzoate (PHMB), a cysteine protease inhibitor, dynorphin A at the subthreshold dose of 0.5 nmol significantly produced an antinociceptive effect during the second phase. This effect was significantly antagonized by nor-binaltorphimine, a selective kappa-opioid receptor antagonist, but not by naltrindole, a selective delta-opioid receptor antagonist. At the same dose of 0.5 nmol, dynorphin A in combination with phosphoramidon, an endopeptidase 24.11 inhibitor, produced a significant antinociceptive effect during both phases. The antinociceptive effect was significantly antagonized by naltrindole, but not by nor-binaltorphimine. Phenylmethanesulfonyl fluoride (PMSF), a serine protease inhibitor, bestatin, a general aminopeptidase inhibitor, and captopril, an angiotensin-converting enzyme inhibitor, were all inactive. The degradation of dynorphin A by mouse brain extracts in vitro was significantly inhibited only by the cysteine protease inhibitors PHMB and N-ethylmaleimide, but not by PMSF, phosphoramidon, bestatin or captopril. The present results indicate that cysteine proteases as well as endopeptidase 24.11 are involved in two steps in the degradation of dynorphin A in the mouse brain, and that phosphoramidon inhibits the degradation of intermediary delta-opioid receptor active fragments enkephalins which are formed from dynorphin A.

Animals↗

PubMed2001

High density O-glycosylation of the MUC2 tandem repeat unit by N-acetylgalactosaminyltransferase-3 in colonic adenocarcinoma extracts.

A synthetic peptide corresponding to the human MUC2 tandem repeat unit was glycosylated in vitro using UDP-GalNAc and extracts of colonic adenocarcinoma and paired normal mucosa, followed by fractionation of the products by reverse phase high-performance liquid chromatography. Several peaks of glycopeptides with different numbers of GalNAc residues attached were detected. It is notable that the adenocarcinoma extract was capable of glycosylating peptides to a much greater extent than was normal mucosa. The levels of mRNA for N-acetylgalactosaminyltransferases-1, -2, and -3 were determined by reverse transcription-PCR. Only N-acetylgalactosaminyltransferase-3 mRNA was expressed at a higher level in the adenocarcinoma than in the normal tissue. When the MUC2 tandem repeat peptide was glycosylated with a mixture of the normal mucosa extract and recombinant N-acetylgalactosaminyltransferase-3, larger amounts of glycopeptides with higher contents of GalNAc residues were produced. The MUC2 tandem repeat peptides glycosylated extensively by recombinant N-acetylgalactosaminyltransferase-1, -2, or -3 were prepared and characterized. Substitution at each Thr residue, as revealed by Edman degradation sequencing, in conjunction with evidence obtained on mass spectrometry indicated a heterogeneous pattern of site-specific glycosylation within the MUC2 tandem repeat. It was found that maximum numbers of 6, 8, and 11 GalNAc residues were incorporated by N-acetylgalactosaminyltransferases-1, -2, and -3, respectively, and that only N-acetylgalactosaminyltransferase-3 could completely glycosylate both consecutive sequences composed of three and five Thr residues in the MUC2 tandem repeat unit. These results suggest that O-glycosylation of the clustered Thr residues is a selective process controlled by N-acetylgalactosaminyltransferase-3 in the synthesis of clustered carbohydrate antigens.

Acetylgalactosamine↗

PubMed2001

cGMP-dependent protein kinase phosphorylates and inactivates RhoA.

Small GTPase Rho and cGMP/cGMP-dependent protein kinase (cGK) pathways exert opposing effects in specific systems such as vascular contraction and growth. However, the direct interaction between these pathways has remained elusive. We demonstrate that cGK phosphorylates RhoA in vitro at Ser188, the same residue phosphorylated by cAMP-dependent protein kinase. In HeLa cells transfected with constitutively active cGK (C-cGK), stress fiber formation induced by lysophosphatidic acid or V14RhoA was blocked. By contrast, C-cGK failed to inhibit stress fiber formation in cells transfected with mutant RhoA with substitution of Ser188 to Ala. C-cGK did not affect actin reorganization induced by Rac1 or Rho-associated kinase, one of the effectors for RhoA. Furthermore, C-cGK expression inhibited the membrane translocation of RhoA. Collectively, our findings suggest that cGK phosphorylates RhoA at Ser188 and inactivates RhoA signaling. The physiological relevance of the direct interaction between RhoA and cGK awaits further investigation.

Actins↗

PubMed2001

Characterization of adriamycin-induced G2 arrest and its abrogation by caffeine in FL-amnion cells with or without p53.

We investigated the effect of Adriamycin on FL-amnion (FL) cells. After treatment with the drug, the cells arrested at G2, but we did not detect an increase in the p21 levels. We established a p53-deficient derivative of these cells, in which G2 arrest also occurred after treatment with Adriamycin, suggesting that the arrest we observed in these cells is independent of the p53 pathway. Low doses of Adriamycin (100-200 ng/ml) induced G2 arrest, while late S-phase arrest was observed at high doses (500-1000 ng/ml) in both FL and p53-deficient FL cells. Accumulation of cyclin B1 was detected only in cells arrested at G2, and not in those arrested at S phase, suggesting that the S-phase checkpoint functioned efficiently even in p53-deficient FL cells. In both cell lines, caffeine-induced activation of CDC2 kinase was detected only in cells arrested at G2 and CDC2 kinase-activated cells died exhibiting features of apoptosis. CDC2 kinase activation was inhibited by cycloheximide. Furthermore, cycloheximide inhibited activation of CDK2:cyclin A, which normally precedes CDC2 kinase activation in caffeine-treated cells. These results suggest that p53 and p21 do not have special roles in the S- and G2-phase checkpoints and that CDK2:cyclin A could be the target of the G2-phase DNA damage checkpoint.

Amnion↗

PubMed2001

Observation of untreated patients with neuroblastoma detected by mass screening: a "wait and see" pilot study.

BACKGROUND: Recent studies have indicated that mass screening for neuroblastoma detects tumors that otherwise would have regressed spontaneously without recognition. Therefore, we started an observation program for these patients to determine how frequently spontaneous regression occurs. PROCEDURE: Eighteen patients were detected by mass screening between June 1994 and December 1996. Eight of these cases matched the following criteria and entered the observation program: Stage I or II, less than 5 cm in diameter; no involvement of large vessels or organs; not difficult to resect; informed consent. If there were an increase in tumor size, an elevation of tumor markers, or evidence of metastasis, the tumor would be immediately resected. RESULTS: Five of the eight cases showed spontaneous regression. Although the remaining three tumors were resected 6-10 months after diagnosis, all patients survived without evidence of recurrence. CONCLUSIONS: At least 60% of neuroblastoma cases who entered our observation program regressed spontaneously.

Adrenal Gland Neoplasms↗

PubMed2001

Photocrosslinkable polysaccharides for in situ hydrogel formation.

In situ photopolymerization is an exciting new technique for tissue engineering. Two photocrosslinkable polysaccharides composed of alginate and hyaluronan are described that upon photolysis form soft, flexible, and viscoelastic hydrogels. The degree of methacrylate modification and thus covalent affects mechanical properties such as swelling, compression, and creep compliance. Significant swelling is observed in aqueous solution; these hydrogels can swell up to 14 times their dry weight. Both hydrogels exhibit low phase angles and (G*) values indicative of viscoelastic materials. The hyaluronan based hydrogel is stronger and more resilient than the corresponding alginate gel. SEM and AFM studies on both hydrogels show smooth and uniform surfaces at the macroscopic level with salient features observed only on the nanometer scale. Rapid polymerization by an optical trigger allows for controlled in situ photopolymerization in a minimally invasive manner, indicating that these hydrogels are relevant for biomedical applications such as sealing wounds and reconstructing soft tissues.

Algorithms↗

PubMed2001

Long-term implantation test and tumorigenicity of polyvinyl alcohol hydrogel plates.

Two types of flat plates made from a polyvinyl alcohol (PVA) hydrogel with a water content of 80 and 20 (PVA-H80, PVA-H20), 20 x 10 x 1 mm in size, were subcutaneously implanted into each of 50 young, male Wistar rats. As a control, a sham operation was done on another set of 50 rats (Sham Op group). The shape and transparency of the PVA hydrogel were unchanged for up to 24 months. Tumors arose in 14 rats from the PVA-H80 group. In the PVA-H20 group, tumors appeared in 15 rats. The average tumor latency was 598 +/- 109 days in the PVA-H80 and 637 +/- 94 days in the PVA-H20. There was no difference in tumor incidence between the PVA-H20 and PVA-H80 groups (p < 0.05). In the Sham Op group, no malignant tumors appeared. Histopathologically, the tumors induced by hydrogel plates were malignant tumors resembling fibrosarcoma or malignant fibrous histiocytoma. This indicates that PVA hydrogel implants also induce solid state carcinogenesis at a similarly high rate to medical grade hydrophobic material reported in a previous study.

Absorbable Implants↗

PubMed2001

Nitric oxide regulates mitochondrial respiration and functions of articular chondrocytes.

OBJECTIVE: Biologic effects of nitric oxide (NO) have been shown to increase under hypoxic conditions. Because the oxygen tension in joint cavities of patients with arthritis is fairly low, biologic effects of NO would be expected to be significantly large in these compartments. This study was undertaken to investigate the effects of NO on the energy metabolism and functions of articular chondrocytes under different oxygen tension conditions. METHODS: Articular chondrocytes from rabbits were cultured under various oxygen concentrations in the presence or absence of NO and NOC18, an NO donor. Cellular respiration was measured using a Clark-type oxygen electrode. Levels of ATP in the cells were determined according to the luciferin-luciferase method. Cellular synthesis of proteoglycans was determined by measuring the incorporation of radioactivity (derived from 35S-labeled SO4) into glycosaminoglycans. Expression of stress-related proteins was evaluated by Western blotting analysis using specific antibodies. RESULTS: Respiration and ATP synthesis of cultured chondrocytes were inhibited by NO, particularly under low oxygen concentrations. The presence of either NO or specific inhibitors of mitochondrial electron transport suppressed the synthesis of proteoglycans without affecting cell viability. When exposed to NO, cellular levels of heat-shock protein 70 (hsp70) and heme oxygenase 1 (HO-1) increased markedly. The presence of inhibitors of mitochondrial electron transport also increased cellular levels of hsp70 and HO-1. CONCLUSION: These results suggest that NO generated in the joint might inhibit energy metabolism and the synthesis of proteoglycans of chondrocytes, thereby modulating pathophysiologic processes occurring in patients with arthritis.

Adenosine Triphosphate↗

PubMed2001

GABAergic control of synaptic summation in hippocampal CA1 pyramidal neurons.

The primary function of neurons is to integrate synaptic inputs and to transmit the results to other cells. It was shown previously that separate excitatory inputs to hippocampal pyramidal neurons are summated nonlinearly. In the hippocampus, responses of pyramidal neurons are influenced by GABAergic inputs in feed-forward or feedback manner, and also by oscillatory network activities. It is likely that these GABAergic inputs regulate the way synaptic inputs are summated. To examine the roles of GABAergic inputs on synaptic summation, we made whole-cell recordings from the cell bodies of CA1 pyramidal neurons in rat hippocampal slices while stimulating two independent input pathways with short interstimulus intervals, and examined the manner by which postsynaptic potentials were summated. We found that: 1) the summation of the perforant pathway and the Schaffer collateral pathway inputs was sublinear when the interval between two inputs was shorter than 30 ms, 2) the blockade of GABA(A) receptors partially suppressed the sublinearity, and 3) further blockade of GABA(B) receptors removed the sublinearity totally. We also found that 4) the summation was superlinear under the concomitant blockade of GABA(A) and GABA(B) receptors when the two inputs arrived with no delay. Thus our study demonstrates that GABAergic inputs are responsible for keeping the summation of two separate inputs on CA1 pyramidal neurons sublinear.

Animals↗

PubMed2001

Three-color flow cytometric study on lymphocytes derived from thymic diseases.

BACKGROUND: Anterior mediastinal masses derive from a variety of diseases. Thymomas have been shown to commonly hold CD4(+)CD8(+) double-positive (DP) lymphocytes, and identification of this subset by two-color flow cytometric study was suggested to help diagnosis of thymoma. Several other thymic diseases, however, possibly hold CD4(+)CD8(+) DP lymphocytes. In this study, we utilized the three-color flow cytometric method for further examination of the phenotypes of lymphocytes in the thymic diseases. MATERIALS AND METHODS: One hundred eight specimens (77 primary and 10 metastatic thymomas, 10 thymic carcinomas, 2 thymic carcinoids, 4 malignant lymphomas, 2 seminomas, an inflammatory pseudotumor, and 2 nonneoplastic thymic hyperplasias) were subjected to the study. The expressions of CD3, CD4, and CD8 on tumor-associated lymphocytes were evaluated by three-color flow cytometric study. RESULTS: The proportion of the CD4(+)CD8(+) DP subset was more than 30% in all 78 lymphocyte-rich thymomas, in 2 malignant lymphomas, and in both thymic hyperplasias. CD3 expression of the CD4(+)CD8(+) DP subset ranged from a negative to a high level in thymomas and thymic hyperplasias, while it was restricted to a particular level in CD4(+)CD8(+) DP-type malignant lymphomas. The proportion of CD3(+) cells in the CD4(+)CD8(-) single-positive subset was consistently less than 90% in the lymphocyte-rich thymomas, while it was more than 90% in the thymic hyperplasias. CONCLUSION: Although identification of the CD4(+)CD8(+) DP subset in the tumor-associated lymphocytes does not necessarily indicate thymoma, a further characterization of thymic neoplasms possessing the CD4(+)CD8(+) DP subset was enabled by three-color flow cytometric study, suggesting the utility of this method as an ancillary tool for differential diagnosis of these diseases.

CD3 Complex↗

PubMed2001

Dopamine D2 receptors in the insular cortex and the personality trait of novelty seeking.

Human personality has been considered to have a neurochemical background. We examined the relation between extrastriatal dopamine D2 receptor binding in living human brain and the personality trait of novelty seeking that has been proposed to be related to dopaminergic function in the brain. We measured extrastriatal dopamine D2 receptors of 24 healthy young male subjects using [(11)C]FLB 457 positron emission tomography. The personality trait of each subject was assessed by the Temperament and Character Inventory (TCI). Correlation of dopamine D2 receptor binding with novelty seeking was calculated using region-of-interest analysis and statistical parametric mapping based on the binding potential images generated using a reference tissue model. A significant negative correlation was observed between binding potential values and the novelty seeking scores on TCI in the right insular cortex. No significant correlation was observed in any other region. Our result indicates that there is a significant association between dopamine D2 receptor binding and the human novelty seeking trait in the right insular cortex.

Adult↗

PubMed2001

Molecular biological markers and micrometastasis in resected non-small-cell lung cancer. Prognostic implications.

OBJECTIVES: Recent advances in molecular biology and genetics have created new diagnostic and treatment possibilities in clinical oncology. We evaluated the usefulness of molecular biological factors in primary tumor and micrometastasis in the bone marrow and pathological negative (pN0) lymph nodes as prognostic parameters in non-small-cell lung cancer (NSCLC) patients. METHODS: Pathological specimens were collected from 129 NSCLC patients to analyze molecular biological markers, including K-ras, p53, Rb, p16, loss of heterozygosity (LOH) at 3p, vascular endothelial growth factor (VEGF), and telomerase activity. Bone marrow samples from 250 NSCLC patients and pN0 lymph nodes from 85 of these patients were collected for micrometastasis detection by immunohistochemistry against cytokeratin. RESULTS: p53 abnormalities and 3p LOH were significantly associated with reduced patient survival in adenocarcinoma, whereas VEGF expression was significantly associated with reduced survival in a squamous cell carcinoma histological subtype by univariate or multivariate analysis. We identified micrometastatic tumor cells in bone marrow of 78 (31.2%) of 250 patients and in pN0 lymph nodes of 26 (30.6%) of 85 patients. Both bone marrow and lymph nodal micrometastases were associated with decreased survival among patients with stage I, however, only lymph nodal micrometastasis had a significant impact on survival. CONCLUSIONS: Molecular biological features of primary tumor and micrometastatic status appear useful in defining groups of patients with a poor prognosis who could benefit from adjuvant systemic treatment.

Adult↗

PubMed2001

Activated Ras modifies the proliferative response of rheumatoid synovial cells to TNF-alpha and TGF-alpha.

OBJECTIVE: To study the role of the Ras/mitogen-activated protein kinase (MAPK) pathway in the proliferative response of rheumatoid synovial fibroblast (RSF) to tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-alpha. METHODS: V-Ki-ras gene was introduced into RSF using a retrovirus and the proliferative response of these cells to TNF-alpha or TGF-alpha was estimated by measuring the uptake of 3H-thymidine. The effect of a mitogen-activated protein kinase kinase (MEK) inhibitor, PD98059, was also investigated. RESULTS: Consistent with previous reports, TNF-alpha and TGF-alpha stimulated the proliferation of RSF. When the v-Ki-ras gene was expressed, the basal growth rate of these cells was increased, but their growth was suppressed by TNF-alpha or TGF-alpha. The latter effect was abolished when the cells were exposed to a relatively low concentration of PD98059. CONCLUSION: Ras modulates the proliferative response of RSF to TNF-alpha and TGF-alpha.

Apoptosis↗