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A Maruyama

Publications and source records attributed to A Maruyama.

At least 19 recordsLinked to original sources
PubMed2000

Gd(3+)-loaded polyion complex for pH depiction with magnetic resonance imaging.

In clinical diagnosis, gadolinium (Gd) ion/low molecular weight chelater complexes have been used as MRI contrast agents that disperse throughout a particular tissue and cause a brighter appearance in MRI. In order to provide a novel imaging concept for MRI, a contrast agent in which the T(1)-relaxation shortening activity (R(1) relaxivity) changes in response to the pH differences was studied. We prepared a polyion complex (PIC) consisting of a polyanionic Gd-chelater, poly(diethylenetriamine-N,N,N',N", N"-pentaaceto, DTPA) (1,3-propanediamide) (denoted as 1a) loaded with Gd ions at a [Gd]/[DTPA unit] ratio of 0.2 (denoted as 1b), and a polycation, poly[2-(diethylamino)ethyl methacrylate] (denoted as 2). The stoichiometric (based on ionic groups) mixture of 1b and 2 formed complex coacervates from pH 5 to pH 8. The R(1) relaxivity of Gd(3+) in the complex was considerably influenced by the pH, and the relative signal intensity changed from 4 at pH 7.2 to 11 at pH 5.0, as determined by an MRI phantom study. The pH responsivity of the complex solution varied with the composition of the PIC (i.e., the mixing ratio of 1b and 2), allowing us to modulate the pH sensibility. The ionic charge balance and swelling of PIC seemingly were related to the pH-dependent R(1) relaxivity change. It is expected that the PIC-based MRI contrast agent may provide a novel category of MRI methods and be useful in improving the detectability of an MRI-based diagnosis.

Cations↗
PubMed2000

Phylogenetic analysis of psychrophilic bacteria isolated from the Japan Trench, including a description of the deep-sea species Psychrobacter pacificensis sp. nov.

Phylogenetic positions of psychrophilic bacteria isolated from the Japan Trench were determined by sequencing analysis of PCR-amplified bacterial small subunit (16S) rRNA genes. Between surface and deep-sea psychrophiles, distinct positions clearly differed within the gamma-Proteobacteria. In phylogenetic analysis using neighbour-joining, maximum-parsimony and maximum-likelihood, strains from surface seawater were inferred to be located in the Halomonas aquamarina-meridiana clade within the family Halomonadaceae. Strains from deep seawater (5000-6000 m), however, formed a novel monophyletic clade within the Moraxella-Psychrobacter branch in the family Moraxellaceae, showing separation from terrestrial and Antarctic relatives. These deep-sea strains were also discriminated from other known Psychrobacter species in phenotype, e.g. limited growth in the absence of NaCl (optimum at about 3% NaCl), positive urease activity, acid production from xylose and arabinose, and the presence of multiple fimbriae. DNA relatedness values among six deep-sea strains were > 85% in DNA-DNA hybridization experiments and > 98% in aligned 16S rDNA sequences. From this evidence, a new species, Psychrobacter pacificensis, is proposed for these deep-sea psychrophiles; the type strain of Psychrobacter pacificensis is strain NIBH P2K6T (= IFO 16270T). Occurrence of psychrobacters in cold Japan Trench deep seawater and at the Antarctic sea surface suggests that deep-sea bacterial habitation and evolution have been mediated by global deep-ocean circulation linked to the sinking of cooled seawater in polar regions.

Cold Temperature↗
PubMed2000

Simultaneous direct counting of total and specific microbial cells in seawater, using a deep-sea microbe as target.

To rapidly and accurately enumerate total and specific microbes in aquatic samples, fluorescent in situ hybridization was combined with direct counting via direct immobilization of cells on a polymer-coated Nuclepore filter. The technique, named FISH-DC, achieved almost complete recovery of total cells and reproducibility of Psychrobacter pacificensis cells of deep-sea origin (error, </=3%) in a mixed culture and in natural seawater. Target cells immobilized on the filter were also successfully enumerated after stringent 3-cycle hybridization and even after a 16-month preservation at -30 degrees C.

Bacillus↗
PubMed1999

Octa- and nonaprenylhydroquinone sulfates, inhibitors of alpha1,3-fucosyltransferase VII, from an Australian marine sponge Sarcotragus sp.

Alpha1,3-fucosyltransferase (Fuc TVII) is a key enzyme in the biosynthesis of selectin ligands. We have isolated two inhibitors of Fuc TVII from a marine sponge Sarcotragus sp. They were characterized as octa- and nonaprenylhydroquinone sulfates on the basis of spectral data. These compounds inhibited Fuc-TVII with IC50 values of 3.9 and 2.4 microg/mL, respectively.

Animals↗
PubMed1999

Poly(L-lysine)-graft-dextran copolymer promotes pyrimidine motif triplex DNA formation at physiological pH. Thermodynamic and kinetic studies.

Extreme instability of pyrimidine motif triplex DNA at physiological pH severely limits its use for artificial control of gene expression in vivo. Stabilization of the pyrimidine motif triplex at physiological pH is therefore of great importance in improving its therapeutic potential. To this end, isothermal titration calorimetry interaction analysis system and electrophoretic mobility shift assay have been used to explore the thermodynamic and kinetic effects of our previously reported triplex stabilizer, poly (L-lysine)-graft-dextran (PLL-g-Dex) copolymer, on pyrimidine motif triplex formation at physiological pH. Both the thermodynamic and kinetic analyses have clearly indicated that in the presence of the PLL-g-Dex copolymer, the binding constant of the pyrimidine motif triplex formation at physiological pH was about 100 times higher than that observed without any triplex stabilizer. Of importance, the triplex-promoting efficiency of the copolymer was more than 20 times higher than that of physiological concentrations of spermine, a putative intracellular triplex stabilizer. Kinetic data have also demonstrated that the observed copolymer-mediated promotion of the triplex formation at physiological pH resulted from the considerable increase in the association rate constant rather than the decrease in the dissociation rate constant. Our results certainly support the idea that the PLL-g-Dex copolymer could be a key material and may eventually lead to progress in therapeutic applications of the antigene strategy in vivo.

DNA↗
PubMed1999

Exercise-induced stunning continues for at least one hour: evaluation with quantitative gated single-photon emission tomography.

To elucidate the after-effect of exercise on left ventricular (LV) function, end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) were evaluated at 1 h after exercise and at rest by technetium-99m tetrofosmin gated myocardial single-photon emission tomography (SPET) using an automated program in 53 subjects. The subjects were grouped as follows: normal scan (n = 16), ischaemia (n = 19) and infarction (n = 18), based on the interpretation of perfusion images. Postexercise LVEF did not differ from resting LVEF in the groups with normal scan and infarction. In patients with ischaemia, postexercise EDV (90+/-17 ml, mean +/-SD) and ESV (44+/-15 ml) were significantly higher than EDV (84+/-15 ml, P = 0.001) and ESV (36+/-14 ml, P<0.0005) at rest. LVEF was significantly depressed 1 h after exercise (53%+/-9% vs 58%+/-9%, P<0.0001). In ischaemic patients with depressed postexercise LVEF, LVEF difference between rest and postexercise showed a significant correlation with the sum of defect scores, which were reversible from exercise to rest perfusion images (r = 0.92, P<0.0001). These results indicate that exercise-induced LV dysfunction (myocardial stunning) continues for at least 1 h in ischaemic patients and that the extent of LVEF depression is determined by the severity of ischaemia.

Blood Volume↗
PubMed1999

Hepatocellular carcinoma complicated by gastrointestinal hemorrhage caused by direct tumor invasion of stomach.

A 65-year-old man with multiple hepatocellular carcinoma (HCC) underwent intra-hepato-arterial chemotherapy (IHAC) through an implantable port over a period of 10 months after transcatheter arterial embolization (TAE) had been performed three times. TAE was performed twice more, and radiotherapy (total dose, 30 Gy; given over a 3-week period) was given for progressive disease in the lateral segment of the liver. Three months after the radiotherapy had finished, the patient suddenly developed melena. Diagnostic imaging revealed gastrointestinal (GI) hemorrhage from HCC invading the stomach, and total gastrectomy and lateral segmentectomy of the liver were performed because the bleeding could not be controlled. The resected specimen disclosed a centrally necrotic tumor that had invaded the lesser gastric curvature and perforated into the lumen. Pathology examination revealed that the HCC had expansively invaded the gastric mucosa, resulting in exposure in the lumen. The possible mechanisms of direct GI invasion by HCC are briefly discussed, with a review of the literature. GI bleeding secondary to involvement by HCC is rare. The enteric radiation injury seems to have been largely responsible for the GI bleeding in this patient.

Aged↗
PubMed1999

Preparation of dendritic graft copolymer consisting of poly-(L-lysine) and arabinogalactan as a hepatocyte specific DNA carrier.

The dendriTIc graft copolymers (PAX) consisting of a poly(L-lysine) (PLL) main chain and grafts of arabinogalactan (AG) were prepared as a liver cell-specific DNA carrier. The copolymers were successfully prepared by reductive amination reaction between a reductive end of AG and epsilon-amino groups of PLL using NaBH3CN as a catalyst. The fractionation of a low molecular weight fraction (Mn = 25 kDa) from a crude AG (Mn = 33 kDa) was essential for the reaction to proceed. The resulting copolymers were isolated by ultrafiltration from unreacted AG and characterized by 1H NMR and gel permeation chromatography equipped with a multiangle laser light scattering detector (GPC-MALLS). The binding and internalization of DNA to hepatoma cells, HepG2, were considerably enhanced by complexing DNA with PAX copolymers. The interactions between PAX/DNA complexes and HepG2 cells were thoroughly inhibited in the presence of a competitor to asialoglycoprotein receptors (ASGP-R), indicating high specificity of the complex to ASGP-R. Furthermore, the PAX copolymers allowed the expression of the reporter gene. Our results reveal that the PAX copolymers may provide a new research tool for cell-specific gene delivery and eventually enhance gene-therapy technology.

Animals↗
PubMed1999

Promotion mechanism of triplex DNA formation by comb-type polycations: thermodynamic analyses of sequence specificity and ionic strength dependence.

We have previously reported that in the presence of poly (L-lysine)-graft-Dextran (PLL-g-Dex) copolymer, the binding constant of the pyrimidine-motif triplex formation at neutral pH is about 100-times higher than that observed without any triplex stabilizer. Here, to explore the mechanism of the promotion effect of the PLL-g-Dex copolymer at neutral pH, the sequence specificity and the ionic strength dependence of the pyrimidine-motif triplex formation was examined in the absence or presence of the copolymer. The sequence specificity of the pyrimidine-motif triplex formation at neutral pH in the presence of copolymer was almost similar to that at acidic pH without the copolymer. As the concentration of magnesium cation increased, the binding constant of the pyrimidine-motif triplex formation without the copolymer increased. On the other hand, the binding constant of the pyrimidine-motif triplex formation in the presence of the copolymer decreased upon the increase in the concentration of magnesium cation. Considering these results in light of counterion condensation (CC) theory, we conclude that the copolymer does not hinder the sequence specificity of the triplex formation, and isolates the triplex formation from the CC effect, which may lead to a net increase in entropy change upon the triplex formation, providing a favorable component to binding constant of the triplex formation.

Base Sequence↗
PubMed1999

Acceleration of DNA strand exchange by polycation comb-type copolymer.

Polycation comb-type copolymers which are composed of poly(L-lysine) backbone and dextran graft chain (PLL-graft-Dex) accelerated DNA duplex and triplex formation and stabilized under physiologically relevant condition remarkably. In this study, we have examined the ability of polycation copolymer in promoting strand exchange between duplex DNA and its complementary single-stranded DNA. It was demonstrated that the strand exchange rate was considerably accelerated by the polycation comb-type copolymer.

DNA↗
PubMed1999

Preparation and evaluation of ODN conjugates with polycation comb-type copolymer.

Oligodeoxynucleotide (ODN) conjugates with the polylysine comb-type copolymer having an ability to promote and stabilize duplex and triplex DNA formation were prepared. 5'-Aminated ODN was succinylated with succinic anhydride. The resulting ODNs having carboxyl terminus were coupled with epsilon-amino groups of the comb-type copolymer using water soluble carbodiimide. The conjugate free from unconjugated ODNs was obtained by gel permeation chromatography. The resulting conjugate maintains ability to form duplex and triplex DNA as estimated by melting curve analysis. Both specificity and stability of the triplex DNA formation were increased by employing the ODN-copolymer conjugates compared to those with their mixture.

Chromatography, Gel↗
PubMed1999

The effect of jogging on P300 event related potentials.

Physical exercise has beneficial effects not only on cardiovascular system and fat metabolism, may also directly effect the cognitive process. We studied the effect of physical exercise on cognitive processes by measuring the P300 event related-potential (ERP) after jogging. Seven well-trained joggers were enrolled in this study and the P300 potentials using auditory oddball paradigm. ERPs were measured before and after 30 minutes of jogging. The amplitude of the P300 significantly increased after jogging compared to values recorded before jogging. These findings suggest that jogging has the effect of facilitating cognitive processes involved in generation of the P300.

Adult↗
PubMed1999

Left ventricular volumes and ejection fraction calculated from quantitative electrocardiographic-gated 99mTc-tetrofosmin myocardial SPECT.

UNLABELLED: We compared the left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) as calculated by Cedars automated quantitative gated SPECT (QGS) to those determined by first-pass radionuclide angiography (FPRNA) and contrast left ventriculography (LVG) in a group of 21 patients (mean age 61.4 +/- 9.2 y). METHODS: A total of 740 MBq 99mTc-tetrofosmin was administered rapidly into the right cubital vein at rest, and FPRNA was performed using a multicrystal gamma camera. One hour after injection, QGS was performed with a temporal resolution of 10 frames per R-R interval. LVG was performed within 2 wk. RESULTS: The EDV, ESV and LVEF calculated by QGS were highly reproducible (intraobserver, r = 0.99, r = 0.99 and r = 0.99, respectively; interobserver, r = 0.99, r = 0.99 and r = 0.99, respectively; P < 0.01) and were more consistent than those determined by FPRNA (intraobserver, r = 0.97, r = 0.95 and r = 0.93, respectively; interobserver, r = 0.86, r = 0.96 and r = 0.91, respectively; P < 0.01). There was a good correlation between EDV, ESV and LVEF by FPRNA and those by LVG (r = 0.61, r = 0.72 and r = 0.91, respectively; P < 0.01), and there was an excellent correlation between QGS and LVG (r = 0.73, r = 0.83 and r = 0.87, respectively; P < 0.01). The mean EDV by QGS (100 +/- 11.3 mL) was significantly lower than by FPRNA (132 +/- 16.8 mL) or LVG (130 +/- 8.1 mL), and the mean ESV by QGS (53.8 +/- 9.3 mL) was lower than by FPRNA (73.0 +/- 13.3 mL). Ejection fraction values were highest by LVG (57.1% +/- 3.2%), then QGS (51.8% +/- 3.0%) and FPRNA (48.9% +/- 2.4%). CONCLUSION: QGS gave more reproducible results than FPRNA. LV volumes and LVEF calculated by QGS correlated well to those by LVG.

Adult↗
PubMed1999

Effects of repeated selective serotonin reuptake inhibitor paroxetine treatments on mouse forced swimming.

Studies were performed in the mouse forced swimming model, a well known experimental depression model, in order to detect the mechanism of the antidepressive effects induced by repeated serotonin reuptake inhibitor (SSRI) dosing. Five-day repeat dosing of a typical SSRI, paroxetine, increased climbing, a distinctive antidepressive behavior, 1 h after but not 1 h before treatment. The coinjection of paroxetine and serum in mice treated with four repeated doses of paroxetine distinctively increased the behavior, but the coinjection of paroxetine and serum in mice without paroxetine did not. These results indicate that repeated dosing of paroxetine produces a serum substance related to the antidepressive effects induced by serotonin neuron activities. Furthermore, the behavior induced by 5-day repeated dosing of paroxetine was decreased by 100 and 10 micrograms/kg of ketanserin (5-HT2 antagonist) and 100 micrograms/kg of LY-278584 (5-HT3 antagonist). The present findings strongly suggest that repeated dosing of paroxetine produces a serum substance stimulating the antidepressive neuronal pathway sensitively mediated by 5-HT2 and 5-HT3 receptor activity.

Animals↗
PubMed1998

Poly(L-lysine)-graft-dextran copolymer: amazing effects on triplex stabilization under physiological pH and ionic conditions (in vitro).

Triplex DNA formation involving unmodified triplex-forming oligonucleotides (TFOs) is very unstable under physiological conditions. Here, we report a novel strategy to stabilize both purine and pyrimidine motif triplex DNA within the rat alpha1 (I) collagen gene promoter under physiologically relevant conditions by a poly(L-lysine)- graft -dextran copolymer. Using an in vitro electrophoretic mobility shift assay, we show that the copolymer almost completely abrogates the inhibitory effects of physiological concentrations of monovalent cations, particularly potassium ion (K+), on purine motif triplex formation involving very low concentrations of an unmodified guanine-rich TFO. Of importance, pH dependency in pyrimidine motif triplex formation involving an unmodified cytosine-rich TFO is also significantly overcome by the copolymer. Finally, the triplex-stabilizing efficiency of the copolymer is remarkably higher than that of other oligocations, like spermine and spermidine. We suggest that the ability of the graft copolymer to stabilize triplex DNA under physiologically relevant pH and salt concentrations will be a cue for further progress in the antigene strategy.

Cations, Monovalent↗
PubMed1998

Novel diglycosyldiacylglycerol from the gram-negative bacterium Deleya marina.

A glycosyldiacylglycerol was isolated from the marine bacterium Deleya marina (ATCC 25374). The structure was determined, mainly by spectral data, to be 1, 2-diacyl-3-O-[alpha-2-amino-2-deoxy-glucopyranose-(1-->4)-O-alpha-idu ronopyranuronic acid]-glycerol. This is, to our knowledge, the first isolation of diglycosyldiacylglycerol containing both iduronopyranuronic acid and 2-amino-2-deoxy-glucopyranose from Gram-negative bacteria.

Glycolipids↗
PubMed1998

A new non-viral DNA delivery vector: the terplex system.

A new DNA delivery vector (the terplex system) based on a balanced hydrophobicity and net surface charge between stearyl-poly(L-lysine), low density lipoprotein (LDL), and genetic material (i.e. plasmid DNA or antisense oligonucleotide) was developed. The pSV-beta-gal plasmid in terplex system showed a 2-5-fold increase in beta-galactosidase expression on murine smooth muscle cells (A7R5) compared to Lipofectin. Delivery of unmodified c-myb antisense oligonucleotide to A7R5 cells was also facilitated significantly by the terplex system, requiring as little as 5.4 nM of antisense oligonucleotide to achieve a 50% antiproliferative effect. Similar antiproliferative effect was observed when the c-myb antisense/terplex formulation was tested on CCD-32 Lu human lung fibroblasts. Characterization of the physical properties of the terplex system was performed using various techniques. Plasmid DNA was condensed by addition of stearyl-PLL and LDL, resulting in the terplex system of about 100 nm in diameter as shown by atomic force microscopy. A strong hydrophobic interaction between stearyl-poly(L-lysine) and LDL was registered by 1H-NMR spectrometry, showing a significant decrease in the epsilon-methylene signal of poly(L-lysine) backbone when stearyl-poly(L-lysine) was mixed with LDL; however, this phenomenon was not observed with unmodified poly(L-lysine). Agarose gel electrophoresis revealed that electrophoretic mobility of the terplex system decreased with increasing amounts of stearyl-poly(L-lysine), indicating that the surface charge of the terplex system became more positive by addition of stearyl-poly(L-lysine). Zeta-potential measurement showed that the terplex system exerted a slightly positive charge (+2 mV) at a 1:1:1 weight ratio of plasmid DNA:LDL:stearyl-poly(L-lysine). The obtained results will be utilized in the design of more efficient and safer DNA delivery vectors for in vivo gene therapy.

Animals↗