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M Okamoto

Publications and source records attributed to M Okamoto.

At least 127 records · Page 7Linked to original sources
PubMed2001

Developmentally regulated expression of brain-specific chondroitin sulfate proteoglycans, neurocan and phosphacan, in the postnatal rat hippocampus.

Developmental changes in the distribution of brain-specific chondroitin sulfate proteoglycans, neurocan and phosphacan/RPTPzeta/beta, in the hippocampus of the Sprague-Dawley rat were examined using monoclonal antibodies 1G2 and 6B4. The 1G2 immunoreactivity was predominant in the neonatal hippocampus while the 6B4 immunoreactivity was predominant in the mature hippocampus. Moderate 1G2 immunoreactivity was detected in the dentate gyrus and subiculum immediately after birth. Immunoreactivity reached a peak on postnatal days 7-10 (P7-P10) when intense 1G2 labeling was present throughout the neuropil layers of the hippocampus except the mossy fiber tract. 6B4 immunoreactivity was limited in the stratum lacunosum moleculare of CA1 in the neonatal hippocampus. It gradually increased by P21 when diffuse 6B4 immunoreactivity was detected in the stratum oriens and radiatum of Ammon's horn, and in the hilus and inner one-third molecular layer of the dentate gyrus, while 1G2 immunoreactivity decreased after P21. In the adult hippocampus, moderate 6B4 immunoreactivity was present in the stratum oriens and radiatum of Ammon's horn, and in the hilus and inner one-third molecular layer of the dentate gyrus, but not in the mossy fiber tract. In addition, strong 6B4 labeling appeared around a subset of neurons after P21. The results suggest that neurocan may have a role in the development of neuronal organization, while phosphacan/RPTPzeta/beta may contribute to the maintenance and plasticity of synaptic structure and function. Furthermore, the absence of 1G2 and 6B4 immunoreactivities in the stratum lucidum suggests that neurocan and phosphacan/RPTPzeta/beta may function as a barrier for the extension of mossy fibers and provide an environment permissive for fasciculation of the mossy fibers.

Animals↗
PubMed2001

Cholesteryl ester transfer protein and atherosclerosis in Japanese subjects: a study based on coronary angiography.

We undertook a cross-sectional analysis on CETP and atherosclerosis among Japanese subjects, by means of CETP mass assay, its gene polymorphism and coronary angiogram. The 110 consecutive patients who underwent coronary angiography were enrolled into the study except for those over 70 years and taking lipid-lowering drugs. Association was analyzed among plasma lipid and lipoproteins, CETP mass, its gene polymorphisms and the finding in coronary angiography. Four CETP-deficiency heterozygotes were identified and excluded from the analysis. CETP mass level showed neither significant correlation with the coronary score (CS) (r=0.06, P=0.52) nor the difference between the groups eventually diagnosed as coronary heart disease (CHD) positive and CHD negative (2.36+/-0.57 vs. 2.24+/-0.21, P=0.24). CETP mass correlated with the total and LDL cholesterol (r=0.43, P<0.001; r=0.36, P<0.001, respectively) but not with HDL cholesterol (r=0.08, P=0.40). While I405V polymorphism had no impact on CETP mass, HDL cholesterol or CS, CETP mass was low with TaqIB polymorphism (B1B1>B2B2, P<0.05) only in the low CS group (<4). Among the lipid and lipoprotein, HDL cholesterol had a greater impact than LDL cholesterol on coronary atherosclerosis. We concluded that CETP mass in plasma does not correlate with coronary atherosclerosis as whole in the non-CETP-deficient. However, the B2B2 genotype in CETP TaqIB polymorphism, only when it decreases the CETP level, may act as a protective factor against atherosclerosis. It should also be noted that CETP mass in general correlates to total and LDL cholesterol, so that it would be an indirect atherogenic parameter.

Carrier Proteins↗
PubMed2001

Synergistic antitumor effect of ionomycin and cisplatin against renal cell carcinoma in vitro and in vivo.

Objectives. To characterize the synergistic antitumor effects of the calcium ionophore, ionomycin, and of cisplatin against human renal cell carcinoma cell line, ACHN, both in vitro and in vivo.Methods. The in vitro growth rate of ACHN after exposure to these compounds was measured, using the MTT assay. The apoptotic features in ACHN were evaluated by DNA ladder analysis and flow cytometric analysis. Bcl-2 and Bax expression levels in ACHN after treatment were examined by Western blot. The synergistic antitumor effects of ionomycin and cisplatin against the growth of established ACHN tumors in athymic nude mice were then tested.Results. The in vitro growth rate of ACHN was suppressed more by ionomycin and cisplatin in combination than by either alone. DNA ladder and fragmentation were more obvious when the cells were incubated with ionomycin and cisplatin together than with either reagent alone. Ionomycin treatment increased the expression level of Bax protein, whereas Bcl-2 expression was not influenced. Although an intraperitoneal injection of cisplatin or an intratumoral injection of ionomycin against subcutaneous ACHN tumors somewhat reduced tumorigenicity in nude mice, the effect was significantly enhanced by a combination of these drugs.Conclusions. The synergistic antitumor effects suggest that ionomycin-based therapy could be a novel therapeutic strategy with which to treat advanced renal cell carcinoma.

Animals↗
PubMed2001

Ductular morphogenesis and functional polarization of normal human biliary epithelial cells in three-dimensional culture.

BACKGROUND/AIMS: The understanding of the physiology and function of human biliary epithelial cells (hBEC) has been improved by studies in monolayer culture systems. The aim was to develop a polarized model to elucidate the mechanisms of ductular morphogenesis and functional differentiation of hBEC. METHODS: The morphological, phenotypic and functional properties of hBEC cultured as three-dimensional aggregates in collagen gel were assessed in medium supplemented with (or without) human hepatocyte growth factor (hHGF) and foetal bovine serum. RESULTS: In the absence of added mitogens and serum, cells maintained as morphologically polarized aggregates, organized around a central lumen, were positive for phenotypic markers of biliary epithelium and negative for markers of other cell types. Functional markers, gamma-glutamyl-transferase, anion exchanger-2, responses to gamma interferon and forskolin induced secretion, were preserved. hHGF increased both the size and number of aggregates and induced hBEC to invade the gel and lumena forming anastomosing networks of cells. CONCLUSIONS: Collagen gel culture in the absence of added growth factors and serum provides a model for analysis of the polarized functions of hBEC. The formation of poorly organized cords of cells in response to hHGF suggests that collagen gel culture may provide a model for the investigation of atypical ductular morphogenesis of the human biliary tract.

Adult↗
PubMed2001

The distribution of PIG-A gene abnormalities in paroxysmal nocturnal hemoglobinuria granulocytes and cultured erythroblasts.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia that is characterized by a deficiency of glycosylphosphatidylinositol-anchored membrane proteins due to phosphatidylinositol glycan-class A (PIG-A) gene abnormalities in various lineages of peripheral blood cells and hematopoietic precursors. The purpose of our study was to clarify the distribution of PIG-A gene abnormalities among various cell lineages during differentiation and maturation in PNH patients. The expression of CD16b or CD59 in peripheral blood granulocytes or cultured erythroblasts from three Japanese PNH patients was analyzed using flow cytometry. PIG-A gene abnormalities in both cell types, including glycophorin A(+) bone marrow erythroblasts, were examined using nucleotide sequence analysis. The expression study of PIG-A genes from each patient was also performed using JY-5 cells.Flow cytometry revealed that the erythroblasts consisted of negative, intermediate, and positive populations in Cases 1 and 3 and negative and intermediate populations in Case 2. The granulocytes consisted of negative and positive populations in all three cases. DNA sequence analysis indicated that all the PNH cases had two or three types of PIG-A gene abnormalities, and that a predominant clone with an abnormal PIG-A gene was different in granulocytes and erythroblasts from Cases 2 and 3. Expression studies showed that all the mutations from the patients were responsible for the null phenotype.PIG-A gene abnormalities result in deficiencies of glycosylphosphatidylinositol-anchored proteins in PNH erythroblasts and granulocytes. The distribution of predominant PNH clones with PIG-A gene abnormalities is often heterogeneous between the cell types, suggesting that a clonal selection of PIG-A gene abnormalities occurs independently among various cell lineages during differentiation and maturation.

Adult↗
PubMed2001

Amyloid precursor protein associates independently and collaboratively with PTB and PDZ domains of mint on vesicles and at cell membrane.

The mint family consists of evolutionarily conserved adapter proteins from Caenorhabditis elegans to mammalian neurons. Three mammalian isoforms, mint1, 2, and 3, are extensively diverted in their N-terminal halves and, in striking contrast, are highly homologous to each other in their C-terminal halves containing phosphotyrosine-binding (PTB) and PSD-95/DLG-A/ZO-1 (PDZ) domains that work as protein-protein interaction modules. Biochemical and genetic analyses revealed that mint1 and LIN-10, a homolog in C. elegans, comprise macromolecular complexes in the presynaptic and postsynaptic terminals, thereby bringing synaptic vesicles to the exocytotic transmitter release site and localizing receptors and ion channels in the specific membrane domains. Amyloid precursor protein is one of the targets of the PTB domain of mint and this interaction modulates its proteolytic procedures ending up with amyloid beta peptide production, but its molecular mechanism is unclear. We show by an in situ hybridization technique that mint3, a ubiquitous isoform, is expressed both in polar cells like neurons, and in non-polar cells, such as glia and ependymal cells, in the mouse brain. In addition, a considerable amount of a human homolog mint3 (approximately 70 kDa) was expressed in a human epithelial cell line. Subcellularly, mint3 is specifically enriched in vesicles in the cytoplasm, cell membrane, and Golgi complex as reserves. A series of deletions or site-directed mutations revealed that mint3 double recognizes an amyloid precursor protein-containing macromolecular complex via the PTB and PDZb domains independently and cooperatively, not only in the cytoplasmic transporting vesicles but even after amyloid precursor protein was targeted and/or inserted to the specific cell membrane domains. From these results we suggest that mint3 links amyloid precursor protein to other components, thereby regulating its transport, endocytosis, and metabolism. Abnormal metabolism of amyloid precursor protein causes an early-onset type of Alzheimer's disease but its molecular mechanism is incompletely understood. The present findings give morphological evidence and a molecular framework of how mint interacts with amyloid precursor protein and modifies its processing on the secretory pathway.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Surgical repair of coronary arteriovenous fistula: a simple and useful approach to identify the fistulous communication.

In repairing coronary arteriovenous fistula (CAVF), it is very important to interrupt the fistulous tract without compromise of normal coronary vessel flow. In our case, selective coronary arteriography showed that the CAVF from the left anterior descending coronary artery (LAD) was very close to the native coronary artery and had a very broad and short neck. We describe a simple and useful approach, by using both antegrade and retrograde coronary perfusion, that makes it possible to certainly protect myocardium and to clearly distinguish the normal native coronary artery from the fistulous tract.

Aged↗
PubMed2001

Phylogenetic identification of Sparganum proliferum as a pseudophyllidean cestode by the sequence analyses on mitochondrial COI and nuclear sdhB genes.

Sparganum proliferum is a larval cestode for which the adult stage is unknown. It is characterized by the continuous branching and budding when parasitized to humans, and causes fatal human sparganosis. However, the biological features of S. proliferum, including its taxonomic status, still remain obscure. Our previous investigation suggested that S. proliferum might be phylogenetically distinct from Spirometra erinaceieuropaei, by the analysis on mitochondrial NADH dehydrogenase subunit 3 (ND3) gene. However, mitochondrial DNA sequence in Platyhelminth is known to have heteroplasmy within a species. Therefore, in the present study, we have investigated the complete nucleotide sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene and the partial nucleotide sequences of nuclear coded succinate dehydrogenase iron-sulfur protein subunit gene (sdhB). The results clearly demonstrated that S. proliferum is a distinct species from S. erinaceieuropaei, and that S. proliferum belongs to the order Pseudophyllidea.

Amino Acid Sequence↗
PubMed2001

Severe impairment of anti-cancer effect of lipoteichoic acid-related molecule isolated from a penicillin-killed Streptococcus pyogenes in toll-like receptor 4-deficient mice.

A lipoteichoic acid-related molecule (OK-PSA) isolated from OK-432, a penicillin-killed Streptococcus pyogenes, is a potent inducer of Th1 cytokines, and elicits anti-cancer effect in tumor-bearing mice. Toll-like receptor (TLR) 4 is a member of the recently identified toll-like receptor family of proteins that has been implicated in lipopolysaccharide-induced cell signaling. In the present study, we have examined the role of TLR4 for OK-PSA-induced Th1-cytokine production and anti-tumor effect by using C3H/HeJ mice in which TLR4 function is impaired. Although OK-PSA strikingly induced Th1 cytokines [interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-12 and IL-18] in the splenocytes derived from control animals (C3H/HeN), OK-PSA did not induce the cytokines in the splenocytes from C3H/HeJ. Furthermore, C3H/HeJ-derived splenocytes acquired the responsiveness to OK-PSA stimulation by overexpression of TLR4 gene. Finally, OK-PSA administration significantly inhibited the tumor growth and lung metastasis of syngeneic squamous cell carcinoma cells in C3H/HeN; however, no effect of OK-PSA was observed in C3H/HeJ. These findings strongly suggest that TLR4 signaling is involved in regulating OK-PSA-induced anti-cancer immunity.

Animals↗
PubMed2001

Comparison of cytokine-inducing activity in a lipoteichoic acid-related molecule isolated from a penicillin-killed group A Streptococcus and from untreated bacteria.

We previously generated a monoclonal antibody, TS-2, that neutralizes the interferon (IFN)-gamma-inducing activity of OK-432, a penicillin-killed streptococcal preparation [J. Immunother. 13 (1993) 232]. Expression of the TS-2-binding antigen was markedly higher in the cell wall of the penicillin-treated Streptococcus pyogenes (OK-432) than in the untreated bacteria (Su-BBM). We here isolated the antigens from OK-432 and Su-BBM, designated OK-PSA and Su-PSA, respectively. OK-432 markedly induced IFN-gamma and interleukin (IL)-18 as compared with Su-BBM in human peripheral blood mononuclear cells (PBMC). Furthermore, all of the Thl-type and Th1-inducing cytokines tested [IFN-gamma, tumor necrosis factor (TNF)-alpha, IL-12 and IL-18] were secreted by OK-PSA-stimulated PBMC far better than by Su-PSA-treated PBMC. In addition, the cytolytic activities of the PBMC were accelerated by the stimulation with OK-432 or OK-PSA far better than by the stimulation with Su-BBM or Su-PSA. These findings strongly suggested that OK-PSA is a highly important molecule of OK-432 and may be a useful immunotherapeutic agent for the patients with malignant diseases as a potent Th inducer. It was also shown that penicillin treatment effectively enhances OK-PSA-induced anti-cancer immunity.

Caspase 1↗
PubMed2001

Activation of cyclin E-dependent kinase activity in colorectal cancer.

Although cyclin E gene amplification is reported to be an important event in various cancers, it is rarely found in human colorectal cancers. As one of the candidate factors of other mechanisms relating to cyclin E, we analyzed cyclin E-dependent kinase activity in colorectal cancer. Protein levels of cyclin E, its catalytic subunit, cyclin-dependent kinase 2 (Cdk2), and p21 and p27 were determined by western blot or immunohistochemistry in 27 colorectal cancers and 10 colorectal adenomas, and compared with adjacent normal colonic mucosa. Enzymatic activity of cyclin E-Cdk2 complex in the colorectal neoplasm was measured using in-gel kinase assay using glutathione S-transferase-retinoblastoma (GST-Rb) fusion protein as substrate, and compared with that of normal mucosa. We clearly showed that although the protein level of cyclin E in colorectal cancer and adenoma was similar to that of adjacent normal mucosa, cylin E-dependent kinase activity was increased in all the cases of colorectal cancers and 90% of colorectal adenomas. The relative kinase activity was significantly higher in colorectal cancer (3.7 +/- 1.7 -fold) than colorectal adenomas (2.0 +/- 0.8-fold) (P < 0.004). The relative expression level of Cdk2 protein in cancer was significantly higher than adenoma (4.4 +/- 2.4 vs 2.7 +/- 1.3, P < 0.04), and p21 and p27 were not detected in colorectal cancer and notably decreased in adenoma. The results of this study strongly suggest that activation of cyclin E-dependent kinase activity may play an important role in colorectal cancer, and its level appears to be related to increased Cdk2 and decreased p21 and p27 amounts rather than cyclin E protein level.

Adenoma↗
PubMed2001

Distribution of the tetracycline resistance determinant tetQ gene in oral isolates of black-pigmented anaerobes in Japan.

We investigated the distribution of tetracycline resistance determinant tetQ in oral black-pigmented anaerobes using a polymerase chain reaction (PCR) METHOD: A total of 185 healthy subjects were divided into 3 groups based on subject age: young (6 to 10 years, n=58), middle (11 to 40 years, n=96), and elder (exactly 70 years, n=31). The prevalence of black-pigmented anaerobes in the gingival sulcus among these groups was 29.3%, 28.2%, and 64.5%, respectively. The prevalence of Prevotella nigrescens among these groups was 22.4%, 15.6%, and 32.3%, respectively, whereas the prevalence of Prevotella intermedia was 1.7%, 4.2%, and 35.5%, respectively. Porphyromonas gingivalis was found only in the elder group (16.1%). The prevalence of the tetQ gene in the black-pigmented anaerobes-positive subjects was almost the same among the 3 groups (approximately 30%). The tetQ gene was found in 27.5% (46 of 167) of P. nigrescens isolates, whereas it was found in only 6.4% (3 of 47) of P. intermedia isolates and in none of the 19 P. gingivalis isolates. Restriction endonuclease digestion patterns of the PCR products revealed 83.6% of 49 tetQ-positive isolates were of subtype A2H2 (AluI type 2, HpaII type 2).

Adolescent↗
PubMed2001

Coordination of microtubules and the actin cytoskeleton by the Rho effector mDia1.

Coordination of microtubules and the actin cytoskeleton is important in several types of cell movement. mDia1 is a member of the formin-homology family of proteins and an effector of the small GTPase Rho. It contains the Rho-binding domain in its amino terminus and two distinct regions of formin homology, FH1 in the middle and FH2 in the carboxy terminus. Here we show that expression of mDia1(DeltaN3), an active mDia1 mutant containing the FH1 and FH2 regions without the Rho-binding domain, induces bipolar elongation of HeLa cells and aligns microtubules in parallel to F-actin bundles along the long axis of the cell. The cell elongation and microtubule alignment caused by this mutant is abolished by co-expression of an FH2-region fragment, and expression of mDia1(DeltaN3) containing point mutations in the FH2 region causes an increase in the amount of disorganized F-actin without cell elongation and microtubule alignment. These results indicate that mDia1 may coordinate microtubules and F-actin through its FH2 and FH1 regions, respectively.

Actins↗
PubMed2001

Serum nm23-H1 protein as a prognostic factor for indolent non-Hodgkin's lymphoma.

Standard chemotherapy has been ineffective for improving the poor 10-year survival rate of patients with indolent lymphoma. However, a wider choice of therapeutic modalities has become recently available, including immunotherapy with monoclonal antibodies and allogeneic peripheral blood stem cell transplantation. Accordingly, a sensitive prognostic indicator is required to identify high-risk patients and to help design new therapeutic approaches for them. We previously reported that the serum nm23-H1 protein level was an independent prognostic factor for aggressive lymphoma. The present study was performed to assess the clinical implications of this protein on indolent lymphoma and whether it can be used to classify the aggressiveness of the disease in order to assist in the individualization of therapy. A total of 130 patients with indolent lymphoma were enrolled in this multicenter study. The serum nm23-H1 protein level was significantly higher in patients with indolent lymphoma than in a normal control group. In addition, indolent lymphoma patients with higher nm23-H1 levels had worse overall and progression-free survival rate than those with lower nm23-H1 levels. Therefore, nm23-H1 in serum may be useful for identifying a distinct group of patients at high risk.

Adolescent↗
PubMed2001

A histomorphometric analysis on bone dynamics in denture supporting tissue under continuous pressure in streptozotocin-induced diabetic rat.

The purpose of this study was to investigate bone dynamics in denture supporting tissue under continuous pressure in the diabetic condition by using bone histomorphometry in relation to initial intensity of continuous pressure exerted through the denture base. The experimental denture base, which was designed to load initial continuous pressure of 0.0, 1.0, 10.0 or 20.0 kPa to the denture supporting tissue, was applied to the molar region of hard palate of streptozotocin-induced diabetic rats. Fluorescent labelled palatal bone tissue was stained with Villanueva bone stain and was prepared for the undecalcified grinding section. In 0.0 kPa group, no bone resorption was observed and bone formation was transiently inhibited after the denture insertion. In 1.0 kPa group, although no bone resorption was observed, the beginning of bone formation after the inhibition of bone formation was later than that in 0.0 kPa group and bone formation dynamics after the resumption of bone formation was similar to that in 0.0 kPa group. In 10.0 and 20.0 kPa groups, bone resorption was observed until 3 and 4 weeks, respectively, and the amount of bone resorption for each group was 60 +/- 16 and 87 +/- 18 microm, respectively. The resumption of bone formation in 10.0 and 20.0 kPa groups were observed at the same stage with 1.0 kPa group, and the bone formation dynamics after the resumption of bone formation in 10.0 and 20.0 kPa groups were also similar to that in 0.0 kPa group. From the results of this study, it was revealed that bone formation following bone resorption did not cause equivalent recovery of the bone surface level to the level observed in the case without bone resorption in the diabetic condition.

Animals↗