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Biomedical subjects

M Naka

Publications and source records attributed to M Naka.

At least 19 recordsLinked to original sources
PubMed2006

Electrogene therapy using endostatin, with or without suicide gene therapy, suppresses murine mammary tumor growth and metastasis.

Syngeneic inoculated metastatic mammary cancers received direct intratumoral injection of a plasmid vector containing either endostatin (pEndo) with or without a suicide gene (pHSVtk), pHSVtk alone or control vector once a week for 8 weeks. We applied electrogene transfer to the tumors after each injection and administered ganciclovir (GCV) to pHSVtk-transfected mice using an osmotic minipump. Anticancer efficacy was monitored using a variety of parameters, namely tumor volume, intratumoral microvessel density and DNA synthesis, number of mice with metastasis, and number of sites of metastasis per mouse. Tumor volume was significantly lower in all therapeutic groups, with the most effective growth suppression in the pEndo+pHSVtk/GCV group. Lymph node metastasis was significantly less frequent in all therapeutic groups, whereas the multiplicity of lung metastases was significantly lower only in the pEndo and pEndo+pHSVtk/GCV groups. All therapeutic groups showed significantly lower intratumor microvessel density and DNA synthesis. The pEndo and pEndo+pHSVtk/GCV groups also showed a significant reduction in the numbers of dilated lymphatic vessels containing intralumenal tumor cells. Our data suggest that endostatin electrogene therapy alone or in combination with pHSVtk/GCV suicide gene therapy is more beneficial than suicide gene therapy alone. The observed antimetastatic activity of endostatin may be of high clinical significance in the treatment of metastatic breast cancer.

Adenoviridae↗
PubMed2005

Semen quality of 324 fertile Japanese men.

BACKGROUND: A number of studies have indicated regional differences in semen quality. To examine the current status in Japan, we undertook a cross-sectional study on the semen quality of fertile Japanese men for comparison with recent European results. METHODS: Semen parameters of 324 fertile men from the Kawasaki/Yokohama area were investigated. The semen parameters were compared with those published for fertile men from four European cities, Copenhagen, Paris, Edinburgh and Turku. RESULTS: When adjusting for confounders such as ejaculation abstinence period and age, the lowest sperm concentrations were detected in men from Kawasaki/Yokohama followed by men from Copenhagen, Paris, Edinburgh and Turku, but only the differences between men from Kawasaki/Yokohama and men from Edinburgh and Turku were significant (P=0.0008 and P<0.0001, respectively). Total sperm count, percentage of motile sperm and percentage of normal sperm observed in Kawasaki/Yokohama were significantly lower than those from all European centres except for motile sperm in men from Paris. CONCLUSIONS: Japanese fertile men had a semen quality at the level of Danish men, who have been reported to have the lowest among investigated men in Europe. The low level of semen quality of the fertile Japanese men may be due to lifestyle or other environmental factors; however, ethnic differences caused by different genetic variation or combinations cannot be ruled out by this study.

Ejaculation↗
PubMed2003

Target validation in hypoxia-induced vascular remodeling using transcriptome/metabolome analysis.

The present study describes combined transcriptome and metabolome analysis for therapeutic target validation in hypoxia-induced vascular remodeling. Exposure to hypoxic conditions resulted in the upregulation of S100C mRNA and increased taurine (2-aminoethanesulfonic acid) content in the rat lung, as demonstrated by differential display and amino-acid content analysis. Hypoxia resulted in transcriptional activation of the S100C promoter through hypoxia-inducible factor-1 (HIF-1). Taurine suppressed HIF-1-mediated increases in S100C transcription. Moreover, oral taurine administration attenuated vascular remodeling in hypoxic rat lung, whereas depletion of endogenous taurine by administration of beta-alanine resulted in increased vascular remodeling. Inhibition of HIF transcription by taurine may be of therapeutic benefit in preventing hypoxia-induced vascular remodeling. In conclusion, we used transcriptome and metabolome analysis to identify a therapeutic low-molecular-weight ligand that plays a critical role in hypoxia-induced vascular remodeling. These techniques provided an excellent strategy for screening and validation of targets.

Animals↗
PubMed2002

Quantitative effects of respiration on venous return during single knee extension-flexion.

Respiration and the muscle pump play major roles in increasing venous return. However, the relative contribution of each of these factors remains unclear. The present study investigates the quantitative effects of interaction between respiration and the muscle pump on femoral venous blood flow (FVBF) during a single voluntary knee extension-flexion (KEF) using duplex-Doppler ultrasound. During various respiration modes, which consisted of arrested respiration, normal respiration and deep respiration (inspiration or expiration), eight subjects performed a supine one-legged voluntary KEF. FVBF was measured during respiration only (Protocol A) and during KEF synchronized with respiration (Protocol B). The difference between FVBF values obtained in Protocol B and Protocol A was defined as DeltaFVBF. When KEF was synchronized with normal or deep respiration, FVBF with inspiration was significantly lower than that with expiration. However, DeltaFVBF was significantly higher with inspiration than with expiration during deep respiration but was not significant during normal respiration. Furthermore, DeltaFVBF was significantly higher at both normal and deep respiration than at arrested respiration. The effects upon the venous return during KEF differed between inspiration and expiration. The present findings indicate that during a single supine KEF, respiration might promote venous return to a range of 1.5- to 2.3-fold DeltaFVBF during arrested respiration.

Adult↗
PubMed2001

Functional characterization of naturally occurring mutants (P405R and P425L) of p73alpha and p73beta found in neuroblastoma and lung cancer.

The novel candidate tumor suppressor p73, a structural and functional homolog of p53, activates various p53 responsive promoters and induces tumor cell apoptosis. Although p73 is infrequently mutated in human cancers, we have previously found two types of p73 mutation with amino acid substitution (P405R and P425L) in primary neuroblastoma and lung cancer. Here we report generations of the p73 mutants with either P405R or P425L substitution and functional analysis of these naturally occurring mutants. Indirect immunofluorescence staining revealed that nuclear accumulation of p73alpha or p73beta was not affected by these mutations. The P425L substitution reduced the ability of p73alpha to transactivate various p53 responsive promoters (p21(Waf1), Mdm2, and Bax). Moreover, this down-regulation was correlated with the reduced capability of p73alpha(P425L) to suppress cell growth in p53-deficient SAOS-2 cells. In contrast, p73beta(P425L) was as effective as wild-type p73beta in transactivation and growth inhibition. On the other hand, the P405R substitution had no significant effect on both the transcriptional activity and the growth-suppressive ability of p73alpha or p73beta. These results suggested that, at least, one of the naturally occurring p73 mutants, p73alpha(P425L), was a functionally defective mutant of p73.

Amino Acid Substitution↗
PubMed2001

Usefulness of the combination of pre- and intraoperative selective intraarterial calcium injection to detect residual insulinomas.

In a 35-year-old woman diagnosed with insulinoma selective intraarterial calcium injection was positive for proximal gastroduodenal artery and inferior pancreaticoduodenal artery involvement preoperatively. Although non-invasive imaging studies were negative, a mass was detected at the pancreatic uncus by intraoperative ultrasonography. Gastroduodenal artery calcium injection was performed after enucleation of the tumor. Following calcium injection, the insulin level was inappropriately increased and further pancreaticoduodenectomy was performed. After excision, another tumor was detected at the head of the pancreas by histopathological examination. As shown, selective intraarterial calcium injection is useful to localize tumors preoperatively and intraoperatively.

Adult↗
PubMed2000

A potent inhibitor of inducible nitric oxide synthase, ONO-1714, a cyclic amidine derivative.

(1S,5S,6R,7R)-7-Chloro-3-imino-5-methyl-2-azabicyclo[4.1.0]heptane hydrochloride (ONO-1714), a novel cyclic amidine analogue, inhibits human inducible nitric oxide (iNOS) with a K(i) of 1.88 nM and rodent iNOS with similar potency in vitro. ONO-1714 was found to be 10-fold selective for human iNOS over human endothelial NOS (ecNOS). When the inhibitory activity of ONO-1714 was compared for iNOS, it was found to be 451-fold and >20,000-fold more potent than L-NMMA and aminoguanidine (AG), respectively. In terms of human iNOS selectivity, ONO-1714 was approximately 34- and 2-fold more selective for iNOS than L-NMMA and AG, respectively. ONO-1714 inhibited the LPS-induced elevation of plasma nitrate/nitrite in mice with an ID(50) value of 0.010 mg/kg, s.c. The maximum tolerated dose of ONO-1714 was 30 mg/kg, i.v. Thus, ONO-1714 represents one of the most potent iNOS inhibitors in vitro and in vivo to date and has great potentials for use as an inhibitor for clarifying the pathophysiological roles of iNOS and for use as a therapeutic agent.

Amidines↗
PubMed2000

Ca(2+)-dependent inhibition of actin-activated myosin ATPase activity by S100C (S100A11), a novel member of the S100 protein family.

S100C (S100A11, calgizzarin) inhibits the actin-activated myosin Mg(2+)-ATPase activity of smooth muscle in a dose-dependent manner: its half-maximal effect occurs at a S100C/actin molar ratio of 0.05 and its maximal effect occurs at a ratio of 0.20. Furthermore, S100C was found to bind to actin with a stoichiometry of 1:6-7 in the presence of Ca(2+), with an affinity of 1 x 10(-6) M determined by cosedimentation assays. Other Ca(2+)-binding proteins such as S100A1, S100A2, S100B, and calmodulin did not inhibit actin-activated myosin Mg(2+)-ATPase activity. Calmodulin, S100A1, and S100B reversed the inhibitory effect of calponin in a Ca(2+)-dependent manner, S100A2 had no effect, and S100C had additional inhibitory effects. The results suggest that S100C might be involved in the regulation of actin-activated myosin Mg(2+)-ATPase activity through its Ca(2+)-dependent interaction with actin filaments.

Actins↗
PubMed2000

Pharmacogenomics and therapeutic target validation in cerebral vasospasm.

One of the most important pharmacogenomic technologies is transcriptome analysis. We used this method to study the change of gene expression profiles in animal models of cerebral vasospasm. We found novel drug target candidates in cerebral vasospasm through pharmacogenomics. By using differential display and quantitative reverse transcriptase-polymerase chain reaction, we found that heme oxygenase-1 (HO-1) mRNA was prominently induced in the basilar artery and modestly in brain tissue in a murine vasospasm model. There was a significant correlation between the degree of vasospasm and HO-1 mRNA levels in the basilar arteries exhibiting vasospasm. Antisense HO-1 oligodeoxynucleotides (ODN) inhibited HO-1 induction in the basilar arteries, but not in the whole brain tissue. This phenomenon was not observed in the nontreatment, sense HO-1 ODN and scrambled ODN treatment arteries. We report, for the first time, the protective effects of HO-1 gene induction by endogenous or clinical compounds in cerebral vasospasm after subarachnoid hemorrhage, a finding that should provide a novel therapeutic target for cerebral vasospasm.

Animals↗
PubMed1999

Deletion of the COOH-terminal region of p73alpha enhances both its transactivation function and DNA-binding activity but inhibits induction of apoptosis in mammalian cells.

The candidate tumor suppressor p73 has a high sequence homology with p53 within the NH2-terminal transactivation domain, the sequence-specific DNA-binding region, and the oligomerization domain. However, p73alpha, which is most abundantly expressed in many tissues and cells among the alternatively spliced forms of p73, has an additional long COOH-terminal tail that might distinguish the function of p53 and p73alpha or other p73 splicing variants. To examine the functional role of the p73alpha COOH-terminal region, we generated a series of p73alpha truncation mutants including p73alpha(1-247) (retaining only a transactivation domain), p73alpha(1-427) (lacking the most COOH-terminal region including a SAM domain), and p73alpha(1-548) (deleting an extreme COOH-terminal region except a SAM domain). When transfected into COS cells, all of p73alpha, p73alpha(1-548), and p73alpha(1-427) localized in the cellular nucleus, whereas p73alpha(1-247) localized in both nucleus and cytoplasm. Intriguingly, when compared with p73alpha, both p73alpha(1-427) and p73alpha(1-548) showed a significant stimulation of the transcription of luciferase reporters harboring three p53-responsive promoters (p21(Waf1), Mdm2, and Bax) in p53-deficient SAOS-2 cells. Gel retardation assays showed that DNA-binding activity of p73alpha(1-427) and p73alpha(1-548) was increased as compared with that of the full-length p73alpha. However, the colony formation assays using SAOS-2 cells demonstrated that, contrary to p73alpha, transfection of p73alpha(1-427) or p73alpha(1-548) resulted in no significant reduction of the number of colonies. These suggest that the distal COOH-terminal region of p73alpha is a cis- or trans-acting regulatory domain and regulates its functions diversely.

Alternative Splicing↗
PubMed1999

Human S100A11 exhibits differential steady-state RNA levels in various tissues and a distinct subcellular localization.

In order to analyze the steady-state RNA levels of S100A11 in different tissues, a cDNA fragment of human S100A11 was isolated from a cDNA library. The obtained fragment was labeled and hybridized to RNA isolated from various tissues. The Northern blot analysis revealed that S100A11 RNA levels varied from high in placenta, through intermediate in heart, lung, kidney, and most muscle samples, to barely detectable in brain. An efficient purification method for recombinant S100A11 yielding high quantities was developed. Furthermore, to examine the subcellular localization of this protein, the human polypeptide S100A11 antibodies were raised in rabbit. S100A11 was found to have a localization distinct from other S100 proteins examined, and is mostly localized in the nucleus, with slight variations among different glioblastoma cell types.

Adult↗
PubMed1999

Regulatory mechanisms of calponin phosphorylation in endothelin-1-induced contraction of porcine coronary artery.

Calponin is an actin-associated protein that appears to play an auxiliary regulatory role in the contraction of smooth muscle. We report here on the mechanisms for regulation of calponin phosphorylation in the endothelin-1-induced contraction of porcine coronary artery. Treatment of strips of porcine artery with endothelin-1 increased calponin phosphorylation and contraction in a concentration-dependent manner. The time course of the phosphorylation was biphasic, with the response to endothelin-1. The extent of phosphorylation reached a maximum within 5 min of stimulation with 10(-7)M endothelin-1 and then it declined rapidly to reach a minimum at 20 min. A potent inhibitor of protein kinase C, GF109203X, inhibited both calponin phosphorylation and contraction that were induced by endothelin-1 at 5 min, without an inhibition for myosin light chain phosphorylation. Protein phosphatase inhibitor, okadaic acid, had no effect on the extent of phosphorylation at 5 min, but it significantly inhibited the subsequent decrease in calponin phosphorylation. In contrast, in PDBu-treated strips of coronary artery, okadaic acid caused a significant steady increase of the extent of calponin phosphorylation. Our results suggest that calponin phosphorylation might be regulated by protein kinase C and okadaic acid sensitive protein phosphatases, in the endothelin-1-induced contraction of porcine coronary artery.

Animals↗
PubMed1999

Cloning and characterization of rat BAT3 cDNA.

HLA-B-associated transcript 3 (BAT3) was originally identified as one of the genes located within human major histocompatibility complex. It encodes a large proline-rich protein with unknown function. In this study, we found that a fragment of the BAT3 gene product interacts with a candidate tumor suppressor, DAN, in the yeast-based two-hybrid system. We cloned the full-length rat BAT3 cDNA from a fibroblast 3Y1 cDNA library. Our sequence analysis has demonstrated that rat BAT3 cDNA is 3617 nucleotides in length and encodes a full-length BAT3 (1098 amino acids) with an estimated molecular mass of 114,801 daltons, which displays an 87.4% identity with human BAT3. The deletion experiment revealed that the N-terminal region (amino acid residues 1-80) of DAN was required for the interaction with BAT3. Green fluorescent protein-tagged BAT3 was largely localized in the cytoplasm of COS cells. Northern hybridization showed that BAT3 mRNA was expressed in all the adult rat tissues examined but predominantly in testis. In addition, the level of BAT3 mRNA expression was more downregulated in some of the transformed cells, including v-mos- and v-Ha-ras-transformed 3Y1 cells, than in the parental cells.

Amino Acid Sequence↗
PubMed1998

Two distinct actin-binding sites of smooth muscle calponin.

Amino acid residues 145-163 of calponin have been proposed as a putative actin-binding site [Mezgueldi, M., Mendre, C., Calas, B., Kassab, R. & Fattoum, A. (1995) J. Biol. Chem. 270, 8867-8876]. Our previous work demonstrated that a fragment of calponin, which corresponded to the first repeated region of calponin and contained the preferred site of phosphorylation by protein kinase C [Nakamura, F., Mino, T., Yamamoto, J., Naka, M. & Tanaka, T. (1993) J. Biol. Chem. 268, 6194-6201] enhanced the Ca2+-induced contraction of permeabilized smooth muscle [Itoh, T., Suzuki, A., Watanabe, Y., Mino, T., Naka, M. & Tanaka, T. (1995) J. Biol. Chem. 270, 20400-20403]. In the present study, we compared the interactions with actin of a synthetic peptide (Lys172-His187) that encompassed the first repeated region with those of three other synthetic peptides. Lys172-His187 inhibited the binding of calponin to F-actin in a concentration-dependent manner but not the binding of caldesmon. Gly141-Gly160, including the above-mentioned putative actin-binding site, also competed with intact calponin to the same extent as Lys172-His187. Inhibition of actomyosin MgATPase activity was observed only with Gly141-Gly160. Lys172-His187 and other tested peptides had no effect. However, Gly141-Gly160 and Lys172-His187 reduced the fluorescence intensity of pyrene-labeled F-actin with approximately equal potency. Moreover, Lys172-His187 was able to reverse the inhibition of actomyosin MgATPase activity by calponin. Lys172-His187 was phosphorylated stoichiometrically by protein kinase C and phosphorylation of this peptide decreased its actin-binding activity. These observations suggest the direct involvement of two distinct actin-binding sites, with different regulatory functions, in the interactions of calponin with actin.

Actins↗
PubMed1998

Repeated writing facilitates children's memory for pseudocharacters and foreign letters.

In a logographic language culture, repeated (hand) writing is a common memory strategy for learning letters and Chinese characters. The purpose of this paper is to determine whether this strategy facilitates children's memory for pseudologographic characters and foreign letters. It also explores which aspect of writing, the use of stroke orders or the writing action itself, is responsible for the effect. First, third, and fifth grade Japanese children participated in the study. Results showed that, for all the subjects, characters and letters were better recalled when learned by writing rather than by looking only (Experiments 1 and 4). The advantage of writing was decreased, however, when the proper writing action prevented (i.e., when subjects were instructed to trace or write without feedback; Experiments 3 and 4) but not when the proper stroke orders were prevented (i.e., when subjects were instructed to write in reverse or random orders; Experiment 2). The results indicate that the writing action, rather than the use of stroke orders, is responsible for the effect.

Child↗