Biomedical subjects

T Matsunaga

Publications and source records attributed to T Matsunaga.

At least 91 records · Page 5Linked to original sources

PubMed2000

Ischemia-induced coronary collateral growth is dependent on vascular endothelial growth factor and nitric oxide.

BACKGROUND: We hypothesized that ischemia-induced expression of vascular endothelial growth factor (VEGF) and the production of NO stimulate coronary collateral growth. METHODS AND RESULTS: To test this hypothesis, we measured coronary collateral blood flow and VEGF expression in myocardial interstitial fluid in a canine model of repetitive myocardial ischemia under control conditions and during antagonism of NO synthase. Collateralization was induced by multiple (1/h; 8/d), brief (2 minutes) occlusions of the left anterior descending coronary artery for 21 days. In controls, collateral blood flow (microspheres) progressively increased to 89+/-9 mL. min(-1). 100 g(-1) on day 21, which was equivalent to perfusion in the normal zone. Reactive hyperemic responses (a measure of the severity of ischemia) decreased as collateral blood flow increased. In N(G)-nitro-L-arginine methyl ester (L-NAME)- and L-NAME+nifedipine-treated dogs, to block the production of NO and control hypertension, respectively, collateral blood flow did not increase and reactive hyperemia was robust throughout the occlusion protocol (P<0.01 versus control). VEGF expression (Western analyses of VEGF(164) in myocardial interstitial fluid) in controls peaked at day 3 of the repetitive occlusions but waned thereafter. In sham-operated dogs (instrumentation but no occlusions), expression of VEGF was low during the entire protocol. In contrast, VEGF expression was elevated throughout the 21 days of repetitive occlusions after L-NAME. Reverse transcriptase-polymerase chain reaction analyses revealed that the predominant splice variant expressed was VEGF(164). CONCLUSIONS: NO is an important regulator of coronary collateral growth, and the expression of VEGF is induced by ischemia. Furthermore, the induction of coronary collateralization by VEGF appears to require the production of NO.

Animals↗

PubMed2000

GST-pi gene-transduced hematopoietic progenitor cell transplantation overcomes the bone marrow toxicity of cyclophosphamide in mice.

Autologous transplantation of bone marrow cells (BMCs) transduced with the multidrug resistance 1 (MDR1) gene or dihydrofolate reductase (DHFR) gene has already been applied in clinical chemoprotection trials. However, anticancer drugs frequently used in high-dose chemotherapy (HDC), such as alkylating agents, are not relevant to MDR1 or DHFR gene products. In this context, we have previously reported that glutathione S-transferase-pi (GST-pi) gene-transduced human CD34(+) cells showed resistance in vitro against 4-hydroperoxicyclophosphamide, an active form of cyclophosphamide (CY). In the present study, a subsequent attempt was made in a murine model to evaluate the effectiveness of transplantation of GST-pi-transduced BMCs to protect bone marrow against high-dose CY. The gene transfection was carried out retrovirally, employing a recombinant fibronectin fragment. Transfection efficiency into CFU-GM was 30%. After the transplantation, recipient mice (GST-pi mice) received three sequential courses of high-dose CY. As the chemotherapy courses advanced, both shortening of recovery period from WBC nadir and shallowing of WBC nadir were observed. In contrast to the fact that three of seven control mice died, possibly due to chemotoxicity, all seven GST-pi mice were alive after the third course, at which point the vector GST-pi gene was detected in 50% of CFU-GM derived from their BMCs and peripheral blood mononuclear cells. When BMCs obtained from these seven mice were retransplanted into secondary recipient mice, 20% of CFU-GM from BMCs showed positive signals for vector GST-pi DNA after 6 months. These data indicate that the GST-pi gene can confer resistance to bone marrow against CY by being transduced into long-term repopulating cells.

Animals↗

PubMed2000

Fully automated chemiluminescence immunoassay of insulin using antibody-protein A-bacterial magnetic particle complexes.

We report a fully automated sandwich immunoassay for the determination of human insulin using antibody-protein A-bacterial magnetic particle (BMP) complexes and an alkaline phosphatase-conjugated secondary antibody. BMPs bearing protein A-MagA inserted on the external surface of the membrane were prepared in the Magnetospirillum sp. AMB-1 transconjugant for a protein A-magA fusion gene. MagA protein was used as an anchor to attach protein A onto the membrane. Protein A-BMP complexes harvested from transconjugant AMB-1 were subsequently complexed with anti-human insulin antibodies by specific binding between the Z domain of protein A and the Fc component of IgG to form the antibody-protein A-BMP complexes. The complexes were quite monodisperse after the binding of the antibody. The BMPs' monodispersity resulted in high signal and low noise in the immunoassay. The luminescence intensity ((kilocounts/s)/microg of antibody) from antibody-protein A-BMP complexes after immunoreaction was higher than that from BMPs chemically conjugated to an antibody. This was explained by a difference in dispersion. The fully automated sandwich immunoassay system using antibody-protein A-BMP complexes made possible precise assays of human insulin in serum.

Alkaline Phosphatase↗

PubMed2000

Microaerobic hydrogen production by photosynthetic bacteria in a double-phase photobioreactor.

The rate of hydrogen production by the marine nonsulfur photosynthetic bacterium, Rhodovulum sp., increased with increasing light intensity. A light intensity of 1800 W/m(2) hydrogen production rate was achieved at the rate of 9.4 micromol/mg dry weight/h. The hydrogen production of this strain was enhanced by the addition of a small amount of oxygen (12 micromol O(2)/reactor). Intracellular ATP content was most efficiently accumulated under microaerobic, dark conditions. Hydrogen production rate by Rhodovulum sp. was investigated using a double-phase photobioreactor consisting of light and dark compartments. This rate was compared with data obtained using a conventional photobioreactor. Rhodovulum sp. produced hydrogen at a rate of 0.38+/-0.03 micromol/mg dry weight/h under microaerobic conditions using the double-phase photobioreactor. The hydrogen production rate was four times greater under microaerobic conditions, as compared with anaerobic conditions using either type of photobioreactor. Hydrogen production using a double-phase photobioreactor was demonstrated continuously at the same rate for 150 h.

Adenosine Triphosphate↗

PubMed2000

Use of anion exchange resin-packed capillary column for rapid detection of anti-double-stranded DNA antibody in systemic lupus erythematosus serum.

An anti-double-stranded (ds) DNA antibodies in serum-detection system was developed based on flow immunoassay with packed-capillary column. Alkaline phosphatase conjugated DNA (ALP-DNA) and anti-dsDNA antibody were separated from unreacted ALP-DNA on the basis of the difference in isoelectric point. A linear anti-dsDNA antibody dose-response curve was obtained between luminescence intensity and concentration of anti-dsDNA antibody in the range 25-200 IU/mL. This simple technique permits the assay of anti-dsDNA autoimmune antibodies within 7 minutes. These results give reduced detection times compared with those previously reported (Lim et al., 1999) through the use of capillary columns.

Alkaline Phosphatase↗

PubMed2000

Respective roles of cyclobutane pyrimidine dimers, (6-4)photoproducts, and minor photoproducts in ultraviolet mutagenesis of repair-deficient xeroderma pigmentosum A cells.

The role of UV light-induced photoproducts in initiating base substitution mutation in human cells was examined by determining the frequency and spectrum of mutation in a supF tRNA gene in a shuttle vector plasmid transfected into DNA repair deficient cells (xeroderma pigmentosum complementation group A). To compare the role of two major UV-induced photoproducts, cis-syn cyclobutane-type pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs), each photoproduct was removed from UV-irradiated plasmid by photoreactivation before transfection. Removal of either CPDs or 6-4PPs by in vitro photoreactivation reduced the mutation frequency while keeping the mutation distribution and the predominance of G:C-A:T transitions as UV-irradiated plasmid without photoreactivation, indicating that both cytosine-containing CPDs and 6-4PPs were premutagenic lesions for G:C-A:T transitions. On the other hand, A:T-G:C transitions were not recovered from plasmids after the removal of 6-4PPs, whereas this type of mutation occurred at a significant level (11%) after the removal of CPDs. Thus, the premutagenic lesions for the A:T-G:C transition are 6-4PPs. Removal of both CPDs and 6-4PPs resulted in the disappearance of mutational hot spots and random distribution of mutation as observed in unirradiated control plasmids. However, the mutational spectrum of photoreactivated plasmids differed significantly from that of unirradiated plasmids. A characteristic feature is a high portion of A:T-T:A transversions (11%) in the photoreactivated plasmid. This mutation is due to nondipyrimidinic "minor" photoproducts, and the mutation spectrum suggests that TA*, the major photoproduct of thymidylyl-(3'-5')-deoxyadenosine, is the premutagenic lesion for this mutation. This is the first report revealing the distinct mutagenic roles of the major UV photoproducts and "minor" photoproducts by the use of (6-4)photolyase.

Base Sequence↗

PubMed2000

Cloning and characterization of a gene, mpsA, encoding a protein associated with intracellular magnetic particles from Magnetospirillum sp. strain AMB-1.

Proteins located within the lipid bilayer, surrounding the intracellular bacterial magnetic particles (BMP) from Magnetospirillum sp. AMB-1, were separated using SDS-PAGE. Several major proteins of approximate molecular weight 66.2, 35.6, and 24.8 kDa were identified. The N-terminal amino acid sequence of one of these proteins, designated MpsA, was determined and used to design a pair of PCR primers which amplified a 105 bp DNA fragment from AMB-1 genomic DNA. Gene-walking, using anchored PCR, was used to determine the complete nucleotide sequence (954 bp) of the mpsA gene. The mpsA encodes a 317 amino acid protein which does not have an N-terminal cytoplasmic transport signal sequence. Intracellular localization studies were carried out using an mpsA-luc gene fusion expressed in AMB-1 following gene transfer by conjugation. The gene fusion was constructed by cloning a 1.6 kb mpsA fragment upstream of luc in the conjugal plasmid pKLC. The MpsA-Luc fusion protein was preferentially located on the magnetic particle membrane. Although the function of MpsA remains unknown, homology searches suggest similarity with the alpha subunit of acetyl-CoA carboxylase and the CoA-binding motif.

Amino Acid Sequence↗

PubMed2000

Synergism between interferon-gamma and cAMP in induction of hepatocyte growth factor in human skin fibroblasts.

Interferon (IFN)-gamma stimulates hepatocyte growth factor (HGF) production markedly in various human leukemia cell lines, but its positive effect in human skin fibroblasts is slight. We examined the combined effect of IFN-gamma and various HGF inducers on HGF production in human skin fibroblasts. IFN-gamma synergistically enhanced HGF production stimulated by 8-bromo-cAMP, one of the most effective inducers of HGF: HGF secreted from cells incubated with 1 mM of 8-bromo-cAMP, 1000 U/ml of IFN-gamma and both of these was approximately 8, 1.5 and 24 times, respectively, that secreted from untreated cells. The effect of IFN-gamma was dose-dependent and was nullified by an anti-IFN-gamma antibody. Neither IFN-alpha nor IFN-beta had such an enhancing effect, but both these IFNs inhibited the synergistic effect of IFN-gamma and 8-bromo-cAMP. IFN-gamma also synergistically augmented HGF production induced by interleukin-1beta and cAMP-increasing agents cholera toxin, forskolin and prostaglandin E(2). HGF gene expression upregulated by cholera toxin, forskolin and 8-bromo-cAMP was markedly enhanced by IFN-gamma, which was detected as early as 3 h after its addition. The synergy between HGF inducers and IFN-gamma is not common to all HGF inducers, because HGF production stimulated by epidermal growth factor and protein-kinase-C-activating phorbol esters was significantly inhibited by IFN-gamma. These results indicate that IFN-gamma synergistically stimulates cAMP-induced HGF production and inhibits HGF production induced by growth factors and protein kinase C activators in human skin fibroblasts.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Two Tandemly Arrayed Transfer-RNA-Derived SINEs of the Medaka (Oryzias latipes).

Two tandemly arrayed short interspersed repetitive element (SINE) sequences were found in medaka (Oryzias latipes). These two SINE sequences, designated SINE1 and SINE2, were flanked by a 180-bp AT-rich region. Both appeared to be derived from transfer RNA. The former exhibited 80% sequence homology to human tRNA(Ala) and the latter exhibited 94% sequence homology to rat tRNA(Ser). SINE1 contained the retroviral U5 region, whereas SINE2 did not. This is the first sequence-level demonstration of the existence of neighboring SINEs in medaka.

Journal Article↗

PubMed2000

Intralobar bronchopulmonary sequestration evaluated by contrast-enhanced three-dimensional MR angiography.

Bronchopulmonary sequestration (PS) is characterized by non-functioning lung tissue fed from one or several aberrant systemic arteries. The condition is diagnosed by visualizing the feeding arteries using non-invasive CT, MRI, colour Doppler sonography or conventional angiography. We present a 5-year-old boy in whom intralobar sequestration was diagnosed using contrast-enhanced 3D MR angiography, which visualised fine blood vessels in the thoraco-abdominal region without arterial puncture. This technique is useful for diagnosing PS.

Bronchopulmonary Sequestration↗

PubMed2000

Morphological evidence that impaired intraneural microcirculation is a possible mechanism of eighth nerve conduction block in acoustic neuromas.

In an attempt to better understand the mechanism of eighth nerve dysfunction in acoustic neuromas (vestibular schwannomas), we have morphologically examined microvessels and nerve fibers in the intracanalicular portion of eighth nerve specimens attached to these tumors. At the light microscopic level, microvessels were well preserved in all the specimens, even in the extremely flattened or markedly small nerve fascicles. However, the density of microvessels was quite variable in the different specimens, presumably as the result of different levels of compression by the tumors and the subsequent formation of a collateral microcirculation in each nerve. Focal areas of mild endoneurial fibrosis were found in 9 out of 22 specimens examined, but severe and widespread degeneration or demyelination was not found in any of the specimens. Ultrastructural studies frequently revealed mild to moderate abnormalities in myelin sheaths, and occasionally showed endothelial hyperplasia and hypertrophy in all the specimens. These findings are consistent with the slight to moderate reduction of endoneurial blood flow in the eighth nerves. The resultant ischemic condition in the eighth nerve may account for the eighth nerve conduction block in acoustic neuromas.

Adult↗

PubMed2000

Discrimination between Atlantic and Pacific Subspecies of Northern Bluefin Tuna (Thunnus thynnus) by Magnetic-Capture Hybridization Using Bacterial Magnetic Particles.

The previously developed magnetic-capture hybridization technique employing bacterial magnetic particles was applied to discriminate between Atlantic and Pacific subspecies of the northern bluefin tuna (Thunnus thynnus) using specific DNA sequences. Nucleotide sequences of a 925-bp fragment (ATCO) flanking the mitochondrial ATPase and cytochrome oxidase subunit III genes in these two subspecies were compared. Two regions having single-nucleotide and three-nucleotide differences between the subspecies were adopted to design DNA probes (NR1, 21-mer; NR2, 29-mer), and two internal primer sets were designed to amplify DNA fragments containing these regions. The DNA probes were immobilized on bacterial magnetic particles via streptavidin-biotin conjugation and subjected to magnetic-capture hybridization with the digoxigenin-labeled fragments amplified using the internal primers. The luminescence intensities of DNA on bacterial magnetic particles obtained by hybridization between the probes and the complementary fragments were higher than those obtained by hybridization with noncomplementary fragments. These data suggest that this system employing DNA on bacterial magnetic particles may be useful for discrimination of these two subspecies by recognizing a single-nucleotide difference.

Journal Article↗

PubMed2000

Production of eicosapentaenoic acid by a recombinant marine cyanobacterium, Synechococcus sp.

The eicosapentaenoic acid (EPA) synthesis gene cluster from an EPA-producing bacterium, Shewanella sp. SCRC-2738, was cloned into a broad-host range vector, pJRD215, and then introduced into a marine cyanobacterium, Synechococcus sp. NKBG15041c, by conjugation. The transconjugant cyanobacteria produced 3.7 +/- 0.2% (2.24 +/- 0.13 mg/L) EPA (n-3) and 2.5 +/- 0.2% (1.49 +/- 0.06 mg/L) eicosatetraenoic acid (n-3) of the total fatty acids when the cells were cultured at 23 degrees C at a light intensity of 1,000-1,500 Lux. The EPA and eico-satetraenoic acid contents of the cells were increased to 4.6 +/- 0.6% (3.86 +/- 1.11 mg/L) and 4.7 +/- 0.3% (3.86 +/- 0.82 mg/L), and 7.5 +/- 0.3% (1.76 +/- 0.10 mg/L) and 5.1 +/- 0.2% (1.19 +/- 0.06 mg/L) when they were cultured at low temperature (18 degrees C) and at lower light intensity (40 Lux), respectively.

Alteromonas↗

PubMed2000

Influences of catecholamines on the sudden death induced in dogs by an antifungal agent, D0870.

We previously reported the occurrence of QT prolongation and sudden death owing to torsades de pointes (TdP) in dogs treated with D0870, an antifungal agent. In the present study, we evaluated the influences of epinephrine and isoproterenol on the onset of TdP each time D0870 was given to 6 anesthetized open-chest dogs at a dosage of 20 mg/kg, 5 times every 40 minutes, by the simultaneous measurements of surface electrocardiogram and epicardial monophasic action potential (MAP). D0870 alone induced noticeable prolongation of the QT interval and action potential duration (APD), but neither ventricular premature contraction (VPC) nor sudden death. In contrast, the additional administration of the catecholamines induced a greater shortening of APD during the later phase of repolarization than during its earlier one and VPCs in all dogs tested, and sudden deaths owing to TdPs in 4 of the 6 dogs treated with D0870. These results suggest that D0870 alone does not induce TdP but that catecholamines play an important part in the development of sudden death induced by D0870 in dogs.

Action Potentials↗

PubMed2000

Molecular mechanism of magnet formation in bacteria.

Magnetic bacteria have an ability to synthesize intracellular ferromagnetic crystalline particles consisting of magnetite (Fe3O4) or greigite (Fe3S4) which occur within a specific size range (50-100 nm). Bacterial magnetic particles (BMPs) can be distinguished by the regular morphology and the presence of an thin organic membrane enveloping crystals from abiologically formed magnetite. The particle is the smallest magnetic crystal that has a regular morphology within the single domain size. Therefore, BMPs have an unfathomable amount of potential value for various technological applications not only scientific interests. However, the molecular and genetic mechanism of magnetite biomineralization is hardly understood although iron oxide formation occurs widely in many higher animals as well as microorganisms. In order to elucidate the molecular and genetic mechanisms of magnetite biomineralization, a magnetic bacterium Magnetospirillum sp. AMB-1, for which gene transfer and transposon mutagenesis techniques had been recently developed, has been used as a model organism. Several findings and information on the BMPs formation process have been obtained within this decade by means of studies with this model organism and its related one. Biomineralization mechanism and potential availability in biotechnology of bacterial magnets have been elucidated through molecular and genetic approach.

Journal Article↗

PubMed2000

Predictive markers for hepatic veno-occlusive disease after hematopoietic stem cell transplantation in adults: a prospective single center study.

Hepatic veno-occlusive disease (VOD) is a major complication after hematopoietic stem cell transplantation (HSCT). Aetiological determinants, diagnosis and treatment remain unclear. Changes in coagulation-fibrinolysis parameters and N-terminal propeptide for type III procollagen (P-III-P) have been studied in patients with or without VOD after HSCT. We prospectively measured protein C activity, tissue plasminogen activator (t-PA), antithrombin III (AT-III), plasminogen activity (PLG), thrombin-antithrombin III (TAT), alpha2-plasmin inhibitor (alpha2-PI),fibrinogen (Fbg) and P-III-P in 44 consecutive adult patients undergoing allogeneic HSCT. Each parameter was determined before conditioning, on day 0 of HSCT and weekly for 5 weeks. Five of the 44 patients developed VOD at a median post HSCT of day 3 (range, day 3 to 12). On repeated analysis of variance (ANOVA), there were significant differences between patients with and without VOD in P-III-P (P < 0.0001), protein C (P < 0.0001), t-PA (P < 0.0001), PLG (P < 0.0001), AT-III(P < 0.0001), Fbg (P < 0.0001), alpha2-PI (P = 0.0002). Levels of P-III-P were significantly higher in patients with VOD than without VOD, before preparative chemotherapy (P < 0.005) and on days 0 and 7 (P < 0.001). On day 0, levels of t-PA were significantly higher in patients with VOD than without VOD (P < 0.05). On day 7, levels of protein C were significantly lower in patients with VOD than without VOD (P < 0.01). On day 0, there were trends of differences (P = 0.0515) between patients with and without VOD in the levels of protein C. These results suggest P-III-P, t-PA and protein C are predictive markers for VOD after HSCT in adults. Moreover, the serum P-III-P level before start of conditioning might indicate patients at risk for developing VOD.

Adolescent↗

PubMed2000

Effect of eccentric clenching on mandibular deviation in the vicinity of mandibular rest position.

Although the mechanical compression of the temporomandibular joint (TMJ), which could be caused by bruxism, would probably result in a slight change of the occlusal relationship, the effect of clenching in the eccentric mandibular position on the occlusal contact has not yet been clarified. This study aimed to investigate the effect of eccentric clenching on bilateral condylar position and thus to estimate any change of occlusal contact. Before and after voluntary clenching, with one third of the maximal voluntary clenching force, for 3 min at the canine edge-to-edge position, vertical deviation of the bilateral condyles was measured at the 1 mm open mandibular position. This was regulated by the three-dimensional position of the anterior reference point which stands for the incisor point. The mean vertical displacement of the highly deviated side of the condyle was 141+/-55 microm, and the calculated mean displacement of the mandibular first molar region of the highly deviated side was 65+/-27 microm. From the results of this study, it was revealed that the eccentric clenching gave rise to three-dimensional deviation of the mandible even when the mandible was in the vicinity of the rest position.

Adult↗

PubMed2000

Vibrating-traction method for mechanical joint distraction.

Mechanical static traction has been adopted as one of the treatment procedures for joint diseases and fractures. The effect of mechanical vibration on the mechanical traction of the temporomandibular joint was studied in six human subjects. A mechanical traction force of 2000 gf was applied as a dynamic traction force with mechanical vibration or as a static traction force. The dynamic traction force with vibration was applied for 5 min to the right temporomandibular joint using a vibrating-traction apparatus which generated mechanical vibrations of 1000, 3000 or 4000 Hz. Application of a static traction force for 5 min was used as a control condition. Vertical condylar displacement was mathematically evaluated from the deviation of the mandible using Eddy current displacement sensors which were attached to the maxillary dental arch. Among the three vibration frequencies, 3000 Hz resulted in the maximum vertical condylar displacement for all six subjects, showing the mean condylar displacement of 668+/-242 microm. In contrast, vibrations of 1000 and 4000 Hz showed a smaller traction effect. Application of the static traction force for 5 min resulted in a mean vertical condylar displacement of 5.7+/-4.9 microm, showing almost no traction effect to the joint. From the results of this study, it was revealed that vibrating traction could distract a joint more effectively than could static traction and that the traction force necessary for effective vibrating traction was less than that for static traction.

Adult↗