Biomedical subjects

K Ikeda

Publications and source records attributed to K Ikeda.

At least 253 records · Page 14Linked to original sources

PubMed2000

Reduced production of lactate during hypoxia and reoxygenation in astrocytes isolated from stroke-prone spontaneously hypertensive rats.

Lactate production and expressions of monocarboxylate transporter 1 (MCT1) and lactate dehydrogenase (LDH) mRNA after hypoxia and reoxygenation (H/R) were examined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) using astrocytes in culture isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY). The basal production of lactate in SHRSP was the same as that observed in WKY. In contrast the lactate levels in SHRSP at 1 and 6 h of reoxygenation after hypoxia were significantly lower than those observed in WKY. In addition LDH and MCT1 mRNA expressions in SHRSP were significantly less strong compared with those in WKY during H/R. These findings indicate that decreased production and slow transport of lactate in SHRSP astrocytes are involved in neuronal energy depletion and possibly encourage neuronal damage, although hereditary weakness of cortical neurons is also related to cell death during H/R.

Animals↗

PubMed2000

C-type natriuretic peptide concentrations in the plasma and cerebrospinal fluid of patients with subarachnoid hemorrhage.

BACKGROUND: Cerebral vasospasm is a poor resulting outcome of a ruptured cerebral aneurysm; to clarify the mechanism of vasospasm it is important to improve this outcome. C-type natriuretic peptide (CNP) is present in the brain as a cerebral vasodilator; it is also an endothelium-derived relaxing factor produced via cGMP. We speculated that CNP might be an inhibitor of cerebral vasospasm after subarachnoid hemorrhage (SAH). METHODS: To clarify the role of CNP in cerebral vasospasm after SAH, we conducted 1 week monitoring of CNP concentrations in the plasma and cerebrospinal fluid (CSF) of 26 patients who had undergone clipping within 24 hours of the occurrence of SAH, and divided them into group A (positive for angiographic spasm) and group B (negative for angiographic spasm). We also examined CNP concentrations in the CSF of patients who were receiving spinal anesthesia for small orthopedic operations, as reference patients. RESULTS: The CNP concentration in the CSF on day 1 was higher than in the reference patients and decreased in both test groups, but we did not observe any significant difference between the groups. CNP concentrations in the plasma did not change in either group. CONCLUSIONS: CNP concentrations in the CSF were high in the acute phase after SAH, whereas plasma CNP concentrations remained constant. However, our findings did not support our hypothesis because we did not find any relationship between vasospasm and changes in CNP concentrations in the CSF.

Adult↗

PubMed2000

Expression of the Sox10 gene during mouse inner ear development.

Mutations in the SOX10 gene, encoding a cell-lineage specific transcription factor, are associated with congenital deafness. We analyzed the expression of Sox10 mRNA in developing mouse inner ear by in situ hybridization. Sox10 mRNA is expressed in the entire epithelia of the otic vesicle at embryonic day 11.5 (E11.5) and in the developing cochlea and vestibule at E13.5. In postnatal day 8 and adult cochleas, Sox10 expression is restricted to the supporting cells of the organ of Corti. These expression profiles suggest that Sox10 is important for development of the cochlea.

Animals↗

PubMed2000

Expression of CD40 in the brain of Alzheimer's disease and other neurological diseases.

We have investigated immunohistochemically the expression of CD40 in post-mortem human brain tissues. In control brain, the blood vessels were stained weakly for CD40. Vascular expression of CD40 was enhanced in the lesions of Alzheimer's disease and some other neurological diseases. In such diseases, reactive microglia were also positive for CD40. The results of this study suggest that CD40 expression by microglia is up-regulated upon a variety of brain insults and is not limited to lesions with amyloid beta-protein deposits.

Alzheimer Disease↗

PubMed2000

Dlxin-1, a novel protein that binds Dlx5 and regulates its transcriptional function.

Dlx5, a member of the Dlx family of homeodomain proteins, plays a critical role in bone development and fracture healing. To understand the molecular mechanism underlying the transcriptional regulation by Dlx5, we performed yeast two-hybrid screening and isolated a novel protein, Dlxin-1, that binds Dlx5 and regulates its transcriptional function. Dlxin-1 cDNA encodes a 775-amino acid protein that has a partial homology with necdin at the C terminus and 25 repeats of hexapeptides (WQXPXX) in the middle region. Dlxin-1 mRNA is expressed in various adult tissues, but not the spleen, and also in osteoblastic and chondrogenic cell lines. During embryogenesis, a strong signal for Dlxin-1 mRNA was found in cell layers surrounding cartilaginous elements in bone rudiment during digit formation. Dlxin-1 binds not only Dlx5 but also Dlx7 and Msx2 and forms homomultimers in vivo. Transfection and reporter gene assays indicate that Dlxin-1 activates the transcriptional function of Dlx5. Therefore, Dlxin-1 may act as a regulator of the function of Dlx family members in bone formation.

Amino Acid Sequence↗

PubMed2000

The effects of sarpogrelate on cardiomyocyte hypertrophy.

Sarpogrelate was developed as an antiplatelet agent antagonizing 5-hydroxytryptamine (5-HT) receptors. It had been reported that 5-HT receptors were expressed in cardiovascular system, and that sarpogrelate had antihypertrophic effects in vascular smooth muscle cells. Cardiac hypertrophy is a major problem in cardiac diseases, so the present study was designed to elucidate the effects of sarpogrelate on cardiac hypertrophy. Cultured rat cardiomyocytes (MCs) and cardiac nonmyocytes (NMCs) were prepared by Percoll gradient and adhesion method and MCs were incubated with (MCs/NMCs) or without NMCs. As an index of protein synthesis of MCs, [3H]-leucine uptake into MCs and MCs/NMCs was measured. Sarpogrelate decreased [3H]-leucine uptake into MCs (maximum 62.6+/-20.6% of control at 10(-4)M, p<0.05 vs. control). Sarpogrelate also significantly attenuated angiotensin-II- and endothelin-1-induced [3H]-leucine uptake. These results indicated that sarpogrelate might have antihypertrophic effects and could be a useful aid for cardiovascular disease.

Angiotensin II↗

PubMed2000

Identification and characterization of human DNA polymerase beta 2, a DNA polymerase beta -related enzyme.

The BRCA1 COOH terminus (BRCT) motif is present in many nuclear proteins that contribute to cell cycle regulation or DNA repair. Polymerase chain reaction-based screening with degenerate primers targeted to the BRCT motif resulted in the isolation of a human cDNA for a previously unidentified DNA polymerase (designated DNA polymerase beta2) that is closely related to DNA polymerase beta (Pol beta). The predicted Pol beta2 protein contains a BRCT motif in its NH(2)-terminal region; its COOH-terminal region exhibits 33% sequence identity to a corresponding region of human Pol beta. The Pol beta2 gene is expressed in a tissue-specific manner, with transcripts being most abundant in testis. A fusion construct comprising Pol beta2 and green fluorescent protein exhibited a predominantly nuclear localization in transfected HeLa cells. Recombinant human Pol beta2 from insect cells exhibited substantial DNA polymerase activity, but it did not possess terminal deoxyribonucleotidyl transferase activity. A truncated Pol beta2 mutant lacking the BRCT motif retained substantial DNA polymerase activity, whereas a mutant Pol beta2 with two alanine point mutations within the DNA polymerase active site did not. These results indicate that Pol beta2 is a Pol beta-related DNA polymerase with a BRCT motif that is dispensable for its polymerase activity.

Amino Acid Motifs↗

PubMed2000

Molecular cloning of ring finger protein 21 (RNF21)/interferon-responsive finger protein (ifp1), which possesses two RING-B box-coiled coil domains in tandem.

We have cloned the full length of a novel cDNA, named ring finger protein 21 (RNF21), composed of the RING finger-B box-coiled coil (RBCC) domain and the B30.2 domain, which are characteristic of the RBCC-B30.2 family. As a structural feature, the RNF21 cDNA possessed at least three kinds of isoforms, due to alternative splicing, consisting of the long form with the RBCC-RBCC-B30.2 domain, the medium form with the RBCC-B30.2 domain, and the short form with only the RBCC domain. Moreover, respective transcripts corresponding to the three isoforms were detected in various human organs by reverse transcription-PCR and Northern blot analyses. Interestingly, the medium form of the RNF21 mRNA expressed most predominantly was dramatically up-regulated within 8-16 h by interferon stimulation of HeLa cells. These findings suggest that RNF21 is a downstream gene that may mediate interferon's biological action.

Alternative Splicing↗

PubMed2000

Serum CYFRA 21-1 is one of the most reliable tumor markers for breast carcinoma.

BACKGROUND: The search for new tumor markers for breast carcinoma has been an area of vigorous study; nonetheless, to the authors' knowledge little new information has emerged beyond the clinical usefulness of CA 15-3. The authors studied serum CYFRA 21-1 in breast carcinoma based on evidence that breast carcinoma expresses cytokeratin 19 fragments and that CYFRA 21-1 is a specific antigen for cytokeratin 19 fragments. METHODS: The serum samples of 86 patients with primary breast carcinoma, 14 patients with recurrent breast carcinoma, 22 patients with benign mammary disease, and 25 healthy controls were provided for measurements of CYFRA 21-1, carcinoembryonic antigen (CEA), and CA 15-3. The relation between clinicopathologic features, prognosis, and disease free survival with serum CYFRA 21-1 titers was studied. RESULTS: There was no difference between the serum CYFRA 21-1 titers from patients with benign mammary disease and those from healthy controls. The sensitivities of CYFRA 21-1 for patients with International Union Against Cancer Stage IV and recurrent tumors were 60% and 64.2%, respectively, which were as high as those for CA 15-3 and superior to those for CEA. The hematogenous recurrence showed a very high sensitivity of 89%. According to the increments of T, N, and M factor numbers, the serum CYFRA 21-1 titers were elevated. No correlation between CYFRA 21-1 and CEA was observed and the correlation between CYFRA 21-1 and CA 15-3 was weak. The univariate and multivariate analyses for survival revealed that serum CYFRA 21-1 levels were an independent indicator of prognosis. CONCLUSIONS: The measurement of the serum CYFRA 21-1 titer in patients with breast carcinoma may be useful in monitoring for recurrence and evaluating the therapeutic effect in patients with advanced disease.

Antigens, Neoplasm↗

PubMed2000

Combination therapy with transcatheter arterial chemoembolization and percutaneous microwave coagulation therapy for hepatocellular carcinoma.

BACKGROUND: A small number of microwave electrode insertions and microwave irradiations were used to obtain complete tumor necrosis in hepatocellular carcinomas (HCC) measuring > 2.0 cm but </= 3.0 cm in greatest dimension. The efficacy of combining transcatheter arterial chemoembolization (TACE) with subsequent percutaneous microwave coagulation therapy (PMCT) was assessed in this study. METHODS: Eighteen patients with cirrhosis and HCCs measuring > 2.0 cm but </= 3.0 cm in greatest dimension underwent TACE followed within 1-2 days by ultrasonographically guided PMCT. RESULTS: On dynamic computed tomography, 17 of the 18 patients showed complete necrosis of their tumor lesions and the treated tumor margins (>/= 5 mm). Necroses of tumors and noncancerous margins surrounding the tumors were obtained using 4 microwave irradiations (1 session) in 14 patients, 5 microwave irradiations (2 sessions) in 2 patients, and 6 microwave irradiations (2 sessions) in 1 patient. The follow-up period was short (12-31 mos), and all patients remained alive. No local recurrences in the treated areas were detected. No fatal complications were observed. Pleural effusion was observed in 1 patient only. CONCLUSIONS: This combined therapy of PMCT applied within 1-2 days of TACE effectively treated HCCs measuring > 2.0 cm but </= 3.0 cm in greatest dimension. A small number of microwave electrode insertions and microwave irradiations were used.

Aged↗

PubMed2000

Self-secretion of fibroblast growth factor-9 supports basal forebrain cholinergic neurons in an autocrine/paracrine manner.

We examined the effect of fibroblast growth factor (FGF)-9 on primary cultures of rat basal forebrain cholinergic neurons (BFCN) obtained at embryonic day 17. FGF-9 enhanced survival of AChE-positive neurons, increased their mean soma size, and up-regulated their choline acetyltransferase (ChAT) activity. The ChAT-promoting effect of FGF-9 was approximately as potent as that of nerve growth factor (NGF) and was greater than those of basic fibroblast growth factor (bFGF), ciliary neurotrophic factor (CNTF), or glia-derived neurotrophic factor (GDNF). Simultaneous addition of FGF-9 and NGF induced extremely high ChAT levels, suggesting that FGF-9 and NGF may enhance cholinergic properties in BFCN via different pathways that can act synergistically. In immunocytochemical and in situ hybridization studies in cultured cells and also in sections of adult rat brain, BFCN showed cytoplasmic immunostaining for FGF-9 and expressed FGF-9 messenger RNA; thus, we concluded that FGF-9 acts on BFCN in an autocrine and/or paracrine manner. Although effective delivery of exogenous FGF-9 into the central nervous system remains a problem to be solved, FGF-9 may be a promising candidate for therapeutic trials in Alzheimer disease.

Animals↗

PubMed2000

Cyclin E as a coactivator of the androgen receptor.

Androgens play an important role in the growth of prostate cancer, but the molecular mechanism that underlies development of resistance to antiandrogen therapy remains unknown. Cyclin E has now been shown to increase the transactivation activity of the human androgen receptor (AR) in the presence of its ligand dihydrotestosterone. The enhancement of AR activity by cyclin E was resistant to inhibition by the antiandrogen 5-hydroxyflutamide. Cyclin E was shown to bind directly to the COOH terminus portion of the AB domain of the AR, and to enhance its AF-1 transactivation function. These results suggest that cyclin E functions as a coactivator of the AR, and that aberrant expression of cyclin E in tumors may contribute to persistent activation of AR function, even during androgen ablation therapy.

Cell Line↗

PubMed2000

Expression of connexin 31 in the developing mouse cochlea.

Connexin 31 (Cx31) mutations cause an autosomal dominant form of high-frequency hearing loss. The immunohistochemical localization of Cx31 in mouse cochlea was studied at different ages between 0 and 60 days after birth (DAB). Cx31-like immunoreactivity was detected in fibrocytes of spiral ligament and spiral limbus at 12 DAB, gradually enhanced with the increase of age and reached the adult pattern on 60 DAB. Immunoreactivity decreased gradually from the basal to apical turn in all developmental stages. The mRNA of Cx31 was also identified by RT-PCR. The distribution of Cx31 and connexin 26 were obviously different in the developing mouse cochlea. The expression and distribution of Cx31 in the development may explain the progressive hearing loss in human Cx31 mutations.

Age Factors↗

PubMed2000

Dominant negative isoform of the Ikaros gene in patients with adult B-cell acute lymphoblastic leukemia.

Gene targeting studies in mice have shown that the transcription factor Ikaros plays an essential role in lymphoid development and as a tumor suppressor in T cells, whereas the related gene Aiolos functions as a tumor suppressor in B cells. We analyzed the expression levels of the Ikaros gene family, Ikaros and Aiolos, in human bone marrow samples from patients with adult acute lymphoblastic leukemia [ALL (n = 46; B-cell ALL = 41; T-cell ALL = 5)]. Overexpression of the dominant negative isoform of Ikaros gene Ik-6 was observed in 14 of 41 B-cell ALL patients by reverse transcription-PCR, and the results were confirmed by sequencing analysis and immunoblotting. None of the other dominant negative isoforms of the Ikaros gene were detected by reverse transcription-PCR analysis. Southern blotting analysis with PstI digestion revealed that those patients with the dominant negative isoform Ik-6 might have small mutations in the Ikaros locus. We did not detect any overexpression of dominant negative isoforms of Aiolos in adult ALL patients. These results suggest that Ikaros plays a key role in human B-cell malignancies through the dominant negative isoform Ik-6.

Adolescent↗

PubMed2000

Modulation of bone remodeling by active vitamin D: its role in the treatment of osteoporosis.

Active vitamin D drugs are used for the treatment of osteoporosis in a number of countries, including Japan. However, their use is controversial. Here, we briefly discuss two issues that are important for understanding the role of active vitamin D (rather than plain vitamin D) in the treatment of osteoporosis: (1) whether or not its skeletal effects are mediated solely through its effects on intestinal calcium absorption in calcium- and vitamin D-replete states, and (2) how it modulates the bone remodeling process.

Animals↗

PubMed2000

Resveratrol inhibits AGEs-induced proliferation and collagen synthesis activity in vascular smooth muscle cells from stroke-prone spontaneously hypertensive rats.

Advanced glycation end-products (AGEs) of plasma proteins and/or matrix proteins are candidate mediators for various vascular complications such as atherosclerosis. We previously reported a significantly larger accumulation of AGEs of the aorta in stroke-prone spontaneously hypertensive rats (SHRSP) than in age-matched Wistar-Kyoto rats (WKY). In this study, we examined the effects of AGEs on vascular smooth muscle cells (VSMC) from SHRSP and WKY rats. We also studied the in vitro effects of resveratrol (3, 4',5-trihydroxystilbene), a natural phytestrogen, on VSMC proliferation, DNA synthesis, and collagen synthesis activity in SHRSP-VSMC. AGEs accelerated the proliferation of SHRSP- or WKY-VSMC in a time- and dose-dependent manner. VSMC from SHRSP were more sensitive to AGEs than VSMC from normotensive WKY. AGEs also significantly increased DNA synthesis and prolyl hydroxylase activity, a marker for collagen synthesis, in SHRSP-VSMC. AGEs-induced increases in TGF-beta1 mRNA in SHRSP-VSMC were significantly greater than in WKY-VSMC. Resveratrol inhibited AGEs-stimulated proliferation, DNA synthesis, and prolyl hydroxylase activity in SHRSP-VSMC in a dose-dependent manner. ICI 182780, a specific estrogen receptor antagonist, partly blocked the inhibitory effects of resveratrol on AGEs-stimulated proliferation, DNA synthesis, and prolyl hydroxylase activity. Resveratrol significantly inhibited AGEs-induced TGF-beta1 mRNA increases in a dose-dependent manner. Thus, resveratrol may confer protective effects on the cardiovascular system by attenuating vascular remodeling and may be clinically useful as a safer substitute for feminizing estrogens in preventing cardiovascular disease.

Animals↗

PubMed2000

Impaired estrogen sensitivity in bone by inhibiting both estrogen receptor alpha and beta pathways.

Although it is well established that estrogen deficiency causes osteoporosis among the postmenopausal women, the involvement of estrogen receptor (ER) in its pathogenesis still remains uncertain. In the present study, we have generated rats harboring a dominant negative ERalpha, which inhibits the actions of not only ERalpha but also recently identified ERbeta. Contrary to our expectation, the bone mineral density (BMD) of the resulting transgenic female rats was maintained at the same level with that of the wild-type littermates when sham-operated. In addition, ovariectomy-induced bone loss was observed almost equally in both groups. Strikingly, however, the BMD of the transgenic female rats, after ovariectomized, remained decreased even if 17beta-estradiol (E(2)) was administrated, whereas, in contrast, the decrease of littermate BMD was completely prevented by E(2). Moreover, bone histomorphometrical analysis of ovariectomized transgenic rats revealed that the higher rates of bone turnover still remained after treatment with E(2). These results demonstrate that the prevention from the ovariectomy-induced bone loss by estrogen is mediated by ER pathways and that the maintenance of BMD before ovariectomy might be compensated by other mechanisms distinct from ERalpha and ERbeta pathways.

Animals↗

PubMed2000

Promoter analysis and chromosomal mapping of human EBAG9 gene.

The human EBAG9 was previously identified as an estrogen responsive gene using CpG-genomic binding site cloning (Watanate et al., (1998) Mol. Cell. Biol. 18: 442-449). Recently it was revealed that the EBAG9 is identical with RCAS1 which is a cancer cell surface antigen implicated in immune escape. Here, we isolated and analyzed the 5'-flanking region of human EBAG9 gene. We determined transcription initiation site, which has a homology with an initiator element YYCAYYYY, and found that TATA motif was absent. Deletion analysis of the 5'-flanking region using MCF-7 breast cancer cells indicated that the sequences -86 to -36 containing the ERE had the basal level of promoter activity and the upstream GC-rich region positively regulated the activity. EBAG9 promoter luciferase reporters containing the ERE could respond to estrogen, and electrophoretic mobility shift assay showed that ERalpha bound to the ERE. Moreover, fluorescent in situ hybridization analysis has shown that the human EBAG9 gene is located at chromosome 8q23 which is frequently amplified in tumors. These findings suggest that the human EBAG9 might be involved in carcinogenesis as an estrogen responsive gene.

Base Sequence↗