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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 199 records · Page 11Linked to original sources
PubMed2000

Suppressive effect of the herbal medicine Oren-gedoku-to on cyclooxygenase-2 activity and azoxymethane-induced aberrant crypt foci development in rats.

The present study is part of a program to obtain effective chemopreventive agents with low toxicity from medicinal herbs and traditional herbal medicines. We previously reported that Oren (Coptidis rhizoma) and Ogon (Scutellariae radix) inhibit azoxymethane (AOM)-induced aberrant crypt foci (ACF) formation. In the present investigation, we found Sanshishi (Gardeniae fructus) and the traditional herbal medicine Oren-gedoku-to (OGT), composed of Ogon, Oren, Sanshishi and Obaku, also have preventive potential. Sanshishi and OGT decreased the numbers of ACF to 25.2 and 59.4% of the control value at 2% in the diet, respectively. Adverse effects, evidenced by body weight loss, were weaker with OGT than component herbs. To investigate their mechanisms of action, the influence on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) activities was studied. Both OGT and Sanshishi inhibited COX-2 but not COX-1, this presumably contributing to their suppressive effects on ACF development. The results suggest that OGT may be useful for colon cancer chemoprevention in terms of efficacy and toxicity.

Animals↗
PubMed2000

Cloning and characterization of rat casein kinase 1epsilon.

Genes differentially expressed in the subjective day and night in the rat suprachiasmatic nucleus (SCN) were surveyed by differential display. A gene homologous to human casein kinase 1epsilon (CK1epsilon) was isolated, which initially appeared to be expressed in the suprachiasmatic nucleus (SCN) in a circadian manner. We here describe the cDNA cloning of the rat CK1epsilon and characterization of the protein products. The rCK1epsilon is predominantly expressed in the brain including the SCN, binds and phosphorylates mPer1, mPer2, and mPer3 in vitro, and translocates mPer1 and mPer3, but not mPer2, to the cell nucleus depending on its kinase activity when coexpressed with these Per proteins in COS-7 cells.

Alternative Splicing↗
PubMed2000

Changes in circadian period and morphology of the hypothalamic suprachiasmatic nucleus in fyn kinase-deficient mice.

Protein tyrosine phosphorylation is involved in intracellular signal transduction and plays important roles in various physiological events. To understand the role of Fyn, a non-receptor type tyrosine kinase of Src family kinases, in the mechanism of circadian rhythms, we analyzed the circadian locomotor behavior and morphology of the hypothalamic suprachiasmatic nucleus (SCN), a master circadian oscillator in Fyn mutant mice, because Fyn-like immunoreactive substance was observed in the SCN. Under constant dark (DD) condition the Fyn (-/-) mutant mice showed a free-running circadian rhythm, and the period of the circadian rhythm of the locomotor activity was significantly longer than that of the control mice. Fyn (-/-) mutant mice had abnormal distribution of neurons containing vasoactive intestinal polypeptide (VIP)-like immunoreactive substance in the SCN. These findings suggest that Fyn is involved in the mechanism of circadian oscillation and morphological formation of the SCN. The mechanism of the implication of Fyn discussed with the Fyn's roles in neural network formation and cellular signal transduction pathway.

Animals↗
PubMed2000

Differential involvement of Src family kinases in Fc gamma receptor-mediated phagocytosis.

The tyrosine phosphorylation cascade originated from Fc gamma receptors (Fc gamma Rs) is essential for macrophage functions including phagocytosis. Although the initial step is ascribed to Src family tyrosine kinases, the role of individual kinases in phagocytosis signaling is still to be determined. In reconstitution experiments, we first showed that expression in the RAW 264.7 cell line of C-terminal Src kinase (Csk) inhibited and that of a membrane-anchored, gain-of-function Csk abolished the Fc gamma R-mediated signaling that leads to phagocytosis in a kinase-dependent manner. We next tested reconstruction of the signaling in the membrane-anchored, gain-of-function Csk-expressing cells by introducing Src family kinases the C-terminal negative regulatory sequence of which was replaced with a c-myc epitope. Those constructs derived from Lyn and Hck (a-Lyn and a-Hck) that associated with detergent-resistant membranes successfully reconstructed Fc gamma R-mediated Syk activation, filamentous actin rearrangement, and phagocytosis. In contrast, c-Src-derived construct (a-Src), that was excluded from detergent-resistant membranes, could not restore the series of phagocytosis signaling. Tyrosine phosphorylation of Vav and c-Cbl was restored in common by a-Lyn, a-Hck, and a-Src, but Fc gamma RIIB tyrosine phosphorylation, which is implicated in negative signaling, was reconstituted solely by a-Lyn and a-Hck. These findings suggest that Src family kinases are differentially involved in Fc gamma R-signaling and that selective kinases including Lyn and Hck are able to fully transduce phagocytotic signaling.

Actins↗
PubMed2000

Contribution of automated hematology analysis to the detection of apoptosis in peripheral blood lymphocytes.

Automated hematology analyzers (analyzers) can provide complete blood counts and white blood cell (WBC) differentials in clinical laboratories and alert users to the presence of quantitative and qualitative cell abnormalities through cautionary flags. In this study, we applied analyzers to the screening of apoptotic cells in peripheral blood and examined the triggering capacity of cautionary flags to detect apoptotic cell populations. EDTA-anticoagulated fresh peripheral blood from patients with acute infectious mononucleosis containing atypical lymphocytes comprising 12.3 +/- 4. 0% of WBC was applied to a Beckman-Coulter MAXM A/L Retic (MAXM) analyzer. The lymphocyte cluster spread upward in VOLUME/DF1 scattergrams and the threshold lines between lymphocyte and monocyte clusters shifted upward. Flags for the number and percentage of lymphocytes, variant lymphocytes, and blast cells were generally present for samples containing atypical lymphocytes. After the blood from acute infectious mononucleosis patients was incubated for 4 h at 37 degrees C, peripheral blood smears revealed the presence of morphologically apoptotic cells comprising 9.0 +/- 4.2% of WBC and a comparable reduction of lymphocytes. On the MAXM analyzer, the apoptotic lymphocyte cluster appeared under the lymphocyte cluster in VOLUME/DF1 scattergrams. However, no specific flag was present to alert users to the presence of the apoptotic lymphocyte cluster. We conclude that visual inspection of scattergrams generated by the MAXM analyzer can be useful for the detection of apoptotic lymphocytes in peripheral blood. Cytometry (Comm. Clin. Cytometry) 42:209-214, 2000. Published 2000 Wiley-Liss, Inc.

Apoptosis↗
PubMed2000

Cytological and immunological changes in bronchoalveolar lavage fluid and histological observation of lung lesions in pigs immunized with Mycoplasma hyopneumoniae inactivated vaccine prepared from broth culture supernate.

We have compared the cytology of bronchoalveolar lavage fluid (BALF) and the pathology of lung lesions in pigs immunized with/without Mycoplasma hyopneumoniae inactivated vaccine prepared from broth culture supernate on experimental infection. Numbers of total cells, macrophages, neutrophils and lymphocytes have decreased in BALF of vaccinated pigs following infection. The mean percentage of lung lesions, inflammatory cell infiltration into the airways and T cells accumulation around the bronchi were reduced in vaccinated pigs. The levels of tumor necrosis factor (TNF)-alpha also decreased in vaccinated pigs. These results suggest that the vaccination may contribute to decrease TNF-alpha production, and therefore, inflammatory cell responses in the lung due to M. hyopneumoniae infection were suppressed, resulting in fewer lung lesions.

Animals↗
PubMed2000

The novel G-protein coupled receptor SALPR shares sequence similarity with somatostatin and angiotensin receptors.

A cDNA encoding a novel G-protein coupled receptor (GPCR) was isolated from a human cerebral cortex cDNA library by low stringency hybridization screening. This putative seven-transmembrane domain receptor of 469 amino acids was designated SALPR (Somatostatin- and Angiotensin- Like Peptide Receptor). SALPR shares the highest amount of amino acid similarity with the somatostatin (35% with SSTR5) and angiotensin receptors (31% with AT1). Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the SALPR mRNA is predominantly expressed in human brain regions, particularly the substantia nigra and pituitary, although the mRNA can also be detected in the peripheral tissues, albeit at low levels. Chromosomal mapping by radiation hybrid analysis localized the human SALPR gene to the chromosome 5p15.1-5p14. Transient expression of SALPR in COS-1 cells did not produce any binding sites for somatostatin or angiotensin II, indicating the necessity for further study to discover its ligand and physiological significance.

Amino Acid Sequence↗
PubMed2000

Transmembrane phosphoprotein Cbp regulates the activities of Src-family tyrosine kinases.

The Src family of protein tyrosine kinases (Src-PTKs) is important in the regulation of growth and differentiation of eukaryotic cells. The activity of Src-PTKs in cells of different types is negatively controlled by Csk, which specifically phosphorylates a conserved regulatory tyrosine residue at the carboxy-terminal tail of the Src-PTKs. Csk is mainly cytoplasmic and Src-PTKs are predominantly membrane-associated. This raises a question about the mechanism of interaction between these enzymes. Here we present Cbp--a transmembrane phosphoprotein that is ubiquitously expressed and binds specifically to the SH2 domain of Csk. Cbp is involved in the membrane localization of Csk and in the Csk-mediated inhibition of c-Src. In the plasma membrane Cbp is exclusively localized in the GM1 ganglioside-enriched detergent-insoluble membrane domain, which is important in receptor-mediated signalling. These findings reveal Cbp as a new component of the regulatory mechanism controlling the activity of membrane-associated Src-PTKs.

Amino Acid Sequence↗
PubMed2000

Identification of tranilast-binding protein as 36-kDa microfibril-associated glycoprotein by drug affinity chromatography, and its localization in human skin.

To elucidate the molecular mechanism involved in the suppression of keloids and hypertrophic scars by tranilast, we investigated the target protein of tranilast in bovine skin and aorta. A specific tranilast-binding protein was isolated from both tissues by drug affinity chromatography and was identified as 36-kDa microfibril-associated glycoprotein (36-kDa MAGP). Binding of 36-kDa MAGP to tranilast seemed to be specific since 36-kDa MAGP could be eluted from the drug affinity column by tranilast itself and also binding of 36-kDa MAGP to other anti-allergy drugs (amlexanox and cromolyn) is significantly weaker than that to tranilast. Light and electron microscopic immunohistochemistry detected the protein at the periphery of elastic fibers in normal human skin. In hypertrophic scar tissue, however, 36-kDa MAGP was located on small bundles of microfibrils. These findings provide support for the concept that elastogenesis occurs in scar tissue and 36-kDa MAGP might be one of the targets for tranilast.

Amino Acid Sequence↗
PubMed2000

Expression of vascular endothelial growth factor in patients with acute myocardial infarction.

OBJECTIVE: The purpose of this study was to investigate the clinical significance of vascular endothelial growth factor (VEGF) in acute myocardial infarction (AMI). We also examined the involvement of peripheral blood mononuclear cells (PBMCs), which are a possible source of VEGF in AMI. BACKGROUND: VEGF is a potent endothelial cell-specific mitogen and could affect the outcome of AMI. METHODS: Thirty patients with AMI were used for this study. Serum and PBMCs were isolated from peripheral blood on days 1, 7, 14 and 21 after the onset of AMI. PBMCs were cultured at a density of 5 x 10(6) cells/ml for 24 h. VEGF levels in serum and the culture media were measured by enzyme-linked immunosorbent assay using a specific anti-human VEGF antibody. RESULTS: Serum VEGF levels elevated gradually after the onset of AMI and reached a peak on day 14. VEGF levels in the culture medium of PBMCs after incubation for 24 h (PBMC-VEGF) were maximally elevated 7 days after the onset. Maximum serum VEGF levels showed significant positive correlations with maximum creatine phosphokinase (CPK) levels (r = +0.70, p < 0.001), but maximum PBMC-VEGF levels did not correlate with maximum CPK levels. Patients showing improvement in left ventricular systolic function during the course of AMI showed significantly higher PBMC-VEGF levels than patients without improvement. CONCLUSIONS: The extent of myocardial damage contributes to the elevation of serum VEGF levels in AMI. VEGF produced by PBMCs may play an important role in the improvement of left ventricular function by promoting angiogenesis and reendothelialization after AMI.

Adult↗
PubMed2000

Functional correlation of GABA(A) receptor alpha subunits expression with the properties of IPSCs in the developing thalamus.

GABA(A) receptor alpha1 and alpha2 subunits are expressed differentially with ontogenic period in the brain, but their functional roles are not known. We have recorded GABA(A) receptor-mediated IPSCs from laterodorsal (LD) thalamic relay neurons in slices of rat brain at various postnatal ages and found that decay times of evoked IPSCs and spontaneous miniature IPSCs undergo progressive shortening during the first postnatal month. With a similar time course, expression of transcripts and proteins of GABA(A) receptor alpha2 subunit in LD thalamic region declined, being replaced by those of alpha1 subunit. To further address the causal relationship between alpha subunits and IPSC decay time kinetics, we have overexpressed GABA(A) receptor alpha1 subunit together with green fluorescent protein in LD thalamic neurons in organotypic culture using recombinant Sindbis virus vectors. Miniature IPSCs recorded from the LD thalamic neurons overexpressed with alpha1 subunit had significantly faster decay time compared with control expressed with beta-galactosidase. We conclude that the alpha2-to-alpha1 subunit switch underlies the developmental speeding in the decay time of GABAergic IPSCs.

Animals↗
PubMed2000

Prebeta1-high-density lipoprotein (prebeta1-HDL) concentration can change with low-density lipoprotein-cholesterol (LDL-C) concentration independent of cholesteryl ester transfer protein (CETP).

To clarify whether prebeta1-high-density lipoprotein (prebeta1-HDL) concentration changes with low-density lipoprotein-cholesterol (LDL-C) concentration independent of cholesteryl ester transfer protein (CETP), we determined prebeta1-HDL concentration by native two-dimensional gel electrophoresis in 58 subjects with normal triglyceride and HDL-cholesterol concentrations. We also measured LDL-C and CETP concentrations. In 17 subjects, a second blood sample was taken 1-6 months after the first. We found that prebeta1-HDL concentration was positively correlated with LDL-C concentration (r=0.529, P<0.0001) and with CETP mass (r=0.398, P<0.01). In 17 patients, Deltaprebeta1-HDL was positively correlated with DeltaLDL-C (r=0.635, P<0.01), but not with DeltaCETP mass (r=0.275). In conclusion, prebeta1-HDL concentration changes with LDL-C concentration independent of CETP. These results suggest that prebeta1-HDL concentration may reflect the balance between several regulatory factors, including LDL-C and CETP concentrations.

Adult↗
PubMed2000

GD3 synthase gene expression in PC12 cells results in the continuous activation of TrkA and ERK1/2 and enhanced proliferation.

A rat pheochromocytoma cell line (PC12) transfected with ganglioside GD3 synthase gene showed a marked change in the ganglioside profile and enhanced proliferation and no response of neurite extension to nerve growth factor (NGF) stimulation. In these transfectant cells, a continuous phosphorylation of TrkA and the activation of ERK1/2 without NGF treatment were observed. Proliferation inhibition experiments with kinase inhibitors such as herbimycin A, K-252a, and PD98059 revealed that the enhanced proliferation was actually due to the activation of the Ras/MEK/ERK pathway. A TrkA dimer was detected in the GD3 synthase transfectant cells regardless of NGF treatment by cross-linking and immunoblotting. The increased expression of GD1b and GT1b in these transfectant cells might induce the conformational change of TrkA to form a dimer and to be activated continuously. These results may indicate regulatory roles of gangliosides in cell proliferation under physiological and malignant processes.

Animals↗
PubMed2000

Efficacy and safety of oral estriol for managing postmenopausal symptoms.

OBJECTIVE: to assess the therapeutic efficacy and safety of oral estriol for the treatment of climacteric symptoms in postmenopausal women. METHODS: 68 postmenopausal women with climacteric symptoms received oral estriol, 2 mg/day, daily for 12 months. We evaluated the degree of climacteric complaints with estriol therapy; serum levels of gonadotropins, estradiol (E2) and lipids; biochemical markers of bone metabolism; blood pressure; and side effects both at baseline and during treatment. Climacteric symptoms were assessed according to the menopausal index (MI), a version of the Kupperman index that had been modified for Japanese women. RESULTS: oral estriol therapy significantly reduced total MI scores. The greatest relief was noted for hot flushes, night sweats, and insomnia. Estriol treatment significantly lowered serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations but did not affect any of the other parameters (lipids, bone, liver and blood pressure) during the study period. Slightly vaginal bleeding occurred in 14.3% of those who underwent natural menopausal women. Histologic evaluation of the endometrium and ultrasound assessment of the breasts following 12 months of estriol treatment found normal results in all women. CONCLUSION: Estriol is a safe and effective alternative for relieving climacteric symptoms in postmenopausal Japanese women.

Administration, Oral↗
PubMed2000

X-linked retinoschisis with point mutations in the XLRS1 gene.

BACKGROUND: X-linked retinoschisis (XLRS) is a relatively rare vitreoretinal dystrophy that causes visual loss in young men. Recently, a gene responsible for this disease, designated XLRS1, was identified, and several deleterious gene mutations were reported. OBJECTIVE: To analyze Japanese patients clinically diagnosed as having XLRS formutational changes in the XLRS1 gene. METHODS: Ten patients with XLRS underwent full ophthalmologic examination, including slitlamp biomicroscopy and dilated funduscopy. Genomic DNA was isolated from leukocytes, and all exons of the XLRS1 gene were amplified by polymerase chain reaction and analyzed using a direct sequencing method. RESULTS: Point mutations in the XLRS1 gene were identified in all 10 patients. The mutations were identical in each of 2 pairs of brothers. Six of the point mutations represented missense mutations, 1 was a nonsense mutation, and 1 was a frameshift mutation. Five of the mutations are newly reported herein. CONCLUSIONS: The discovery of new point mutations in this study increases the available information regarding the spectrum of genetic abnormalities and clinical manifestations of XLRS. However, the limited data failed to reveal a correlation between mutation and disease phenotype. CLINICAL RELEVANCE: Identification of mutations in the XLRS1 gene and expanded information on clinical manifestations will facilitate early diagnosis, appropriate early therapy, and genetic counseling regarding the prognosis of XLRS.

Adolescent↗
PubMed2000

Effect of dietary vitamin B6 contents on antibody production.

When mice were placed on diets extreme deficient in vitamin B6, ovalbumin-dependent antibody productions (IgE, IgG1, IgG2a) were significantly suppressed, and alanine aminotransferase activity in the liver was also significantly decreased. In the case of pyridoxine excess (6 mg% = about ten times standard amount) in a 70% casein diet, ovalbumin-dependent antibody productions were also considerably suppressed. These responses were weaker in a low casein (5%) or normal casein (20%) diet than in a 70% casein diet. The administration of high doses of pyridoxine (6 mg%) resulted in the suppression of hepatic cathepsin B activity. Therefore, we conclude that ovalbumin-dependent antibody productions (IgG1, IgE) were suppressed by pyridoxine excess diet (6 mg%), because hepatic cathepsin B activity was suppressed by the excess pyridoxine in diet.

Animals↗
PubMed2000

Changes of cytokines during the course of graft-versus-host disease following bone marrow transplantation: a case report.

Allogeneic bone marrow transplantation was performed in a 24-year-old woman with acute myelogenous leukemia in the first remission (FAB classification: M4). Graft-versus-host disease occurred from around day 150 after bone marrow transplantation. The levels of tumour necrosis factor-alpha, interleukin 12, and intercellular adhesion molecule-1 were elevated in the early stage of graft-versus-host disease, followed by elevation of interleukin 10 and interleukin 8. Her symptoms subsequently improved and all of these parameters became normal. The levels of thrombomodulin and plasminogen activator inhibitor type 1 showed changes that were in parallel with the clinical course. Interleukin 1beta, interleukin 6, interleukin 2, and interferon-gamma showed no changes throughout the course of her graft-versus-host disease. These findings suggested the possibility that release of inflammatory molecules occurred at the onset of graft-versus-host disease and caused vascular endothelial damage, which led to the exacerbation of her disease.

Adult↗