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Biomedical subjects

H Utsumi

Publications and source records attributed to H Utsumi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effects of ACE inhibition on left ventricular failure and oxidative stress in Dahl salt-sensitive rats.

Dahl salt-sensitive (DS) rats fed high-salt diet exert compensated left ventricular (LV) hypertrophy and eventually develop heart failure. Oxidative stress has been shown to be involved in myocardial remodeling and failure and thus might play an important role in this transition from hypertrophy to failure. We measured the amount of reactive oxygen species (ROS) in the myocardium from DS rats by using electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (hydroxy-TEMPO) and also examined the effects of chronic angiotensin-converting enzyme (ACE) inhibition on the transition. We divided DS rats (5 weeks old, 150-200 g) into three groups: low-salt (0.3% NaCl) diet for 10 weeks (LS group), high-salt (8% NaCl) diet for 10 weeks (HS-10+V group), and high-salt diet and cilazapril (10 mg/kg body weight per day) started after 5 weeks of high-salt diet and maintained for 5 weeks (HS-10+Cil group). Systolic blood pressure (mm Hg) was significantly elevated in the HS-10+V (229+/-5) and HS-10+Cil (209+/-5) groups compared with the LS group (141+/-2). The amount of myocardial ROS was not changed after 5 weeks of high-salt diet, but significantly increased in HS-10+V rats compared with LS rats, and was abolished in the HS-10+Cil group. HS-10+V rats exerted the clinical signs of heart failure, including increased lung weight and pleural effusion, associated with LV hypertrophy and LV cavity dilatation. In the HS-10+Cil group, signs of heart failure were significantly attenuated despite only a modest reduction in systolic blood pressure (-20 mm Hg). The progression of LV failure after hypertrophy in high-salt-loaded DS hypertensive rats was associated with increased myocardial ROS, and ACE inhibitor could prevent this transition from compensated hypertrophy to failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Effect of the central nervous system on mucosal growth and apoptosis in the small intestine.

Recently our studies have demonstrated that the central nervous system regulates in part mucosal cell growth and apoptosis in the rat small intestine. Ornithine decarboxylase (ODC) activity is a key enzyme for polyamine synthesis which plays an important role for the intestinal mucosal growth. We have demonstrated that the increase of ODC activity in the duodenum just before the dark period is abolished by truncal vagotomy and that the infusion of 2-deoxy-D-glucose into the third cerebroventricle activates ODC activity in the small intestine. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. Our preliminary data showed that intestinal mucosal apoptosis decreased in the ventromedial-hypothalamus-lesioned rat. These results indicate that the central nervous system, in addition to local factors, is related to regulation of mucosal homeostasis in the intestinal mucosa.

Animals↗
PubMed2001

Increased base change mutations at G:C pairs in Escherichia coli deficient in endonuclease III and VIII.

Various types of mutation induced by oxidative DNA damage, induced by hydrogen peroxide and riboflavin photosensitization, were determined in Escherichia coli (E. coli) mutants deficient in endonuclease III (endo III) and endonuclease VIII (endo VIII). The majority of hydrogen peroxide-induced and spontaneous mutations consisted of G:C to A:T and to T:A base changes, shown on the mutation assay system by a reversion at a specific site of the lacZ gene. Base changes were also localized at G:C pairs in the mutation of the supF gene, induced by riboflavin photosensitization, which specifically yields 7,8-dihydro-8-oxoguanine (8-oxoG). G:C to T:A and to C:G transversions dominated in both mutants. These results suggest that endo III and endo VIII are involved in the repair of oxidative lesions of guanine.

Base Sequence↗
PubMed2001

Requirement for repair of DNA double-strand breaks by homologous recombination in split-dose recovery.

Utsumi, H., Tano, K., Takata, M., Takeda, S. and Elkind, M. M. Requirement for Repair of DNA Double-Strand Breaks by Homologous Recombination in Split-Dose Recovery. Radiat. Res. 155, 680-686 (2001). Split-dose recovery has been observed under a variety of experimental conditions in many cell systems and is believed to be the result of the repair of sublethal damage. It is considered to be one of the most widespread and important cellular responses in clinical radiotherapy. To study the molecular mechanism(s) of this repair, we analyzed the knockout mutants KU70-/-, RAD54-/-, and KU70-/-/RAD54-/- of the chicken B-cell line, DT40. RAD54 participates in the recombinational repair of DNA double-strand breaks (DSBs), while members of the KU family of proteins are involved in nonhomologous end joining. Split-dose recovery was observed in the parent DT40 and the KU70-/- cells. Moreover, the split-dose survival enhancement had all of the characteristics demonstrated earlier for the repair of sublethal damage, e.g., the reappearance of the shoulder on the survival curve with dose fractionation; cyclic fluctuation in cell survival at 37 degrees C; repair and no cyclic fluctuation at 25 degrees C. These results strongly suggest that repair of sublethal damage is due to DSB repair mediated by homologous recombination, and that these DNA DSBs constitute sublethal damage.

Animals↗
PubMed2001

[Study on dopamine D2 binding capacity in vascular parkinsonism].

To investigate whether the striatal dopamine receptor function is involved in the development of vascular parkinsonism (VP), a positron emission tomography (PET) study was conducted on 9 patients with VP by using [11C] N-methylspiperone as the tracer. The rate of binding availability in the striatal dopamine D2 receptor (k3) was determined semiquantitatively, and the values were compared to the predicted normal values based on the results from 7 normal volunteers. Of 9 patients with VP, the normalized D2 receptor binding [%k3] was more than 90% in 5 patients, 89 to 87% in 3, and 75% in one. These values showed no evident correlation with the Hoehn and Yahr stage. The laterality of the striatal %k3 did not correspond to that of the parkinsonism. Thus, the striatal dopamine D2 receptor binding was not severely impaired and did not correlate with the neurological status in patients with VP. This may indicate that striatal dopamine D2 receptor function is not primarily associated with the development of the parkinsonism in VP.

Aged↗
PubMed2000

Treatment with dimethylthiourea prevents left ventricular remodeling and failure after experimental myocardial infarction in mice: role of oxidative stress.

Oxidative stress might play an important role in the progression of left ventricular (LV) remodeling and failure that occur after myocardial infarction (MI). We determined whether reactive oxygen species (ROS) are increased in the LV remodeling and failure in experimental MI with the use of electron spin resonance spectroscopy and whether the long-term administration of dimethylthiourea (DMTU), hydroxyl radical (.OH) scavenger, could attenuate these changes. We studied 3 groups of mice: sham-operated (sham), MI, and MI animals that received DMTU (MI+DMTU). Drugs were administered to the animals daily via intraperitoneal injection for 4 weeks.OH was increased in the noninfarcted myocardium from MI animals, which was abolished in MI+DMTU. Fractional shortening was depressed by 65%, LV chamber diameter was increased by 53%, and the thickness of noninfarcted myocardium was increased by 37% in MI. MI+DMTU animals had significantly better LV contractile function and smaller increases in LV chamber size and hypertrophy than MI animals. Changes in myocyte cross-sectional area determined with LV mid-free wall specimens were concordant with the wall thickness data. Collagen volume fraction of the noninfarcted myocardium showed significant increases in the MI, which were also attenuated with DMTU. Myocardial matrix metalloproteinase-2 activity, measured with gelatin zymography, was increased with MI after 7 and 28 days, which was attenuated in MI+DMTU. Thus, the attenuation of increased myocardial ROS and metalloproteinase activity with DMTU may contribute, at least in part, to its beneficial effects on LV remodeling and failure. Therapies designed to interfere with oxidative stress might be beneficial to prevent myocardial failure.

Animals↗
PubMed2000

A new nitroxyl-probe with high retention in the brain and its application for brain imaging.

In order to estimate free radical reactions and image them in the brain of living animals, a nitroxyl spin-probe, carboxy-PROXYL acetoxymethyl ester (CxP-AM) was newly synthesized. CxP-AM was designed to be hydrolyzed by esterase, but not by lipase, so that it would pass through the blood-brain barrier and be retained in the cytosolic phase of parenchymal cells in the brain after intravenous injection. The pharmacokinetics of CxP-AM was compared with those of carboxy-PROXYL (CxP) and its methyl ester (CxP-M). Carboxyl esterase almost completely hydrolyzed CxP-AM within 3 min. After intravenous injection, the brain retained 1.8 times more CxP-AM than CxP-M, and retained it for more than 30 min. Electron spin resonance computed tomographic (ESR-CT) imaging of CxP-AM in the heads of mice produced marked contrast in the encephalon region, while CxP was distributed only in the extracranial region and CxP-M was distributed in both regions, confirming the pharmacokinetics of CxP-AM. The decay rate of CxP-AM determined with time-resolved ESR-CT imaging was different in the two brain regions, suggesting regional differences in the total reducing capability. CxP-AM should become a powerful probe for the investigation and diagnosis of free radical reactions and their imaging in the brain.

Animals↗
PubMed2000

Direct evidence for increased hydroxyl radicals originating from superoxide in the failing myocardium.

Experimental and clinical studies have suggested an increased production of reactive oxygen species (ROS) in the failing myocardium. The present study aimed to obtain direct evidence for increased ROS and to determine the contribution of superoxide anion (*O(2)(-)), H(2)O(2), and hydroxy radical (*OH) in failing myocardial tissue. Heart failure was produced in adult mongrel dogs by rapid ventricular pacing at 240 bpm for 4 weeks. To assess the production of ROS directly, freeze-clamped myocardial tissue homogenates were reacted with the nitroxide radical, 4-hydroxy-2,2,6, 6,-tetramethyl-piperidine-N-oxyl, and its spin signals were detected by electron spin resonance spectroscopy. The rate of electron spin resonance signal decay, proportional to *OH level, was significantly increased in heart failure, which was inhibited by the addition of dimethylthiourea (*OH scavenger) into the reaction mixture. Increased *OH in the failing heart was abolished to the same extent in the presence of desferrioxamine (iron chelator), catalase (H(2)O(2) scavenger), and 4,5-dihydroxy-1,3-benzene disulfonic acid (Tiron; LaMotte) (*O(2)(-) scavenger), indicating that *OH originated from H(2)O(2) and *O(2)(-). Further, *O(2)(-) produced in normal myocardium in the presence of antimycin A (mitochondrial complex III inhibitor) could reproduce the increase of H(2)O(2) and *OH seen in the failing tissue. There was a significant positive relation between myocardial ROS level and left ventricular contractile dysfunction. In conclusion, in the failing myocardium, *OH was produced as a reactive product of *O(2)(-) and H(2)O(2), which might play an important role in left ventricular failure.

Animals↗
PubMed2000

Development of separable electron spin resonance-computed tomography imaging for multiple radical species: an application to .OH and .NO.

A method of separable ESR-CT (electron spin resonance-computed tomography) imaging for multiple radical species was developed and applied to imaging of .OH and .NO. The algorithm was improved by combining filtered back-projection with a modified algebraic reconstruction technique to enhance accuracy and shorten calculation time. With this algorithm, spectral-spatial images of the phantom consisting of 3-carbamoyl-2,2,5,5,-tetramethylpyrrolidine-N-oxyl and 2-phenyl-4,4,5,5,-tetramethylimidazoline-3-oxide-1-oxyl could be obtained in different directions by rotating the spatial axis. The spatial function of individual radicals was extracted by each of the two methods from each spectral-spatial image. The separative 2D images of each radical were individually constructed using the spatial function obtained with the two methods. By comparing the separative images with the phantom sample, the algorithm for separable ESR-CT imaging was established. This ESR-CT technique was combined with L-band ESR spectroscopy and applied to the separative imaging of .OH and .NO, which were spin trapped with 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) and Fe(2+)-N-methyl-D-glucamine dithiocarbamate complex, respectively. The ESR signal of DMPO-OH decreased gradually during data acquisition, and the decrease was calibrated by extrapolating the signal intensity to the beginning of data sampling. Both the position and size of the individual images for .OH and .NO were in very good agreement with the findings for the sample.

Cyclic N-Oxides↗
PubMed2000

Presynaptic L-type Ca(2)+ channels on excessive dopamine release from rat caudate putamen.

We investigated by means of behavioral and neurochemical studies the role of the nerve terminal L-type voltage sensitive Ca(2)+ channel on dopamine (DA) release. Microinjection of Bay K 8644 (BAYK), an L-type Ca(2)+ channel stimulant, into the rat caudate putamen increased locomotor activity and rearing behavior in a dose-dependent manner, whereas injections into the amygdala had no effect. DA receptor antagonists significantly blocked BAYK-induced hyperactivity. Significant increases of extracellular DA levels were detected by microdialysis 20 min after BAYK administration into caudate putamen and then declined. This increase was influenced by tetrodotoxin, an axonal Na(+) channel blocker. Pretreatment with nimodipine and nicardipine, but not nifedipine, which are 1, 4-dihydropyridine L-type Ca(2)+ channel antagonists, administered into the caudate putamen significantly blocked BAYK-induced hyperactivity and DA efflux. These results indicate that the extraordinary DA release in the caudate putamen was mediated by extreme stimulation of the nicardipine and nimodipine-sensitive L-type Ca(2)+ channel present in the nerve terminal of striatal DA neurons.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Conformational studies on a unique bis-sulfated glycolipid using NMR spectroscopy and molecular dynamics simulations.

The time-averaged solution conformation of a unique bis-sulfated glycolipid (HSO3)2-2,6Manalpha-2Glcalpha-1-sn-2,3-O-alkylglycerol , was studied in terms of the torsional angles of two glycosidic linkages, phi (H1-C1-O-Cx) and psi (C1-O-Cx-Hx), derived from heteronuclear three-bond coupling constants (3JC,H), and inter-residual proton-proton distances from J-HMBC 2D and ROESY experiments, respectively. The dihedral angles of Glcalpha1Gro in glycolipids were determined for the first time. The C1-C4 diagonal line of the alpha-glucose ring makes an angle of approximately 120 degrees with the glycerol backbone, suggesting that the alpha-glucose ring is almost parallel to the membrane surface in contrast with the perpendicular orientation of the beta-isomer. Furthermore, minimum-energy states around the conformation were estimated by Monte Carlo/stochastic dynamics (MCSD) mixed-mode simulations and the energy minimization with assisted model building and energy refinement (AMBER) force field. The Glcalpha1Gro linkage has a single minimum-energy structure. On the other hand, three conformers were observed for the Manalpha2Glc linkage. The flexibility of Manalpha2Glc was further confirmed by the absence of inter-residual hydrogen bonds which were judged from the temperature coefficients of the chemical shifts, ddelta/dT (-10-3 p.p.m. degrees C-1), of hydroxy protons. The conformational flexibility may facilitate interaction of extracellular substances with both sulfate groups.

Computer Simulation↗
PubMed2000

Membrane structure of the hepatitis B virus surface antigen particle.

Expression of S protein, an envelope protein of hepatitis B virus, in the absence of other viral proteins, leads to the secretion of hepatitis B virus surface antigen (HBsAg) particles that are formed by budding from the endoplasmic reticulum membranes. The HBsAg particles produced by mouse fibroblast cells show a unique lipid composition, with 1,2-diacyl glycerophosphocholine being the dominant component. The lipid organization of the HBsAg particles was studied by measuring electron spin resonance (ESR) using various spin-labeled fatty acids, and the results were compared with a parallel study on HVJ (Sendai virus) and vesicles reconstituted with total lipids of the HBsAg particles (HBs-lipid vesicles). HVJ and the HBs-lipid vesicles showed typical ESR spectra of lipids arranged in a lipid bilayer structure. In contrast, the ESR spectra obtained with the HBsAg particles showed that the movement of lipids in the particle is severely restricted and a typical immobilized signal characteristic of tight lipid-protein interactions was also evident. Phosphatidylcholine (PC) in the HBsAg particles was not exchangeable by a PC-specific exchange protein purified from bovine liver, while phospholipase A(2) from Naja naja vemon was able to hydrolyze all the PC in the particles. These analyses suggest that the lipids in the HBsAg particles are not organized in a typical lipid bilayer structure, but are located at the surface of the particles and are in a highly immobilized state. Based on these observations we propose a unique lipid assembly and membrane structure model for HBsAg particles.

Androgen-Binding Protein↗
PubMed2000

Expression of GFRalpha-1, receptor for GDNF, in rat brain capillary during postnatal development of the BBB.

It is well known that the blood-brain barrier (BBB) matures at approximately 2 wk after birth in the rat. Recently, we showed that glial cell line-derived neurotrophic factor (GDNF) enhances the barrier function of porcine endothelial cells forming the BBB in culture. In the present study, we examined the relation between permeability of the BBB, using Evans blue as a tracer, and expression of the GDNF family receptor (GFRalpha-1) during postnatal development of the BBB. Morphometric analysis showed that exudation of Evans blue from capillaries of the cerebral cortex progressively decreased until postnatal day 21. Inversely, immunohistochemical examinations showed expression of GFRalpha-1 in the capillaries at postnatal day 3 and expression that reached the same levels as observed in adult rats by postnatal day 10. However, c-ret, which is thought to mediate a signal evoked by binding of GDNF to GFRalpha-1, was not expressed in the capillaries of the brain cortex in 3-mo-old rats. On the other hand, the tight junction proteins occludin and ZO-1 appeared to be fully expressed at birth. The reciprocal relation between GFRalpha-1 expression and the permeability of the BBB strongly suggests active participation of GDNF in postnatal development of the BBB, although the mechanism(s) involved is still veiled.

Animals↗
PubMed2000

Expression of receptors for glial cell line-derived neurotrophic factor (GDNF) and neurturin in the inner blood-retinal barrier of rats.

The retina is protected from somatic circulation by the blood-retinal barrrier (BRB) composed of tight junctions between retinal vascular endothelial cells (the inner BRB) and those between retinal pigment epithelial cells (the outer BRB). Our recent studies showed that glial cell line-derived neurotrophic factor (GDNF) secreted from astrocytes regulates the permeability of the BBB. In the present study, we immunohistochemically examined the expression of GDNF, neurturin (NTN) and their receptors, GFRalpha1 for GDNF and GFRalpha2 for NTN, because the capillaries of the inner BRB show specialization very similar to the blood-brain barrier (BBB). GDNF and NTN were detected in glial fibrillary acidic protein (GFAP)-positive cells, including Müller cells. GFRalpha1 and GFRalpha2 were localized in von Willebrand factor-positive cells. GDNF and NTN enhanced the barrier function of endothelial cells derived from porcine brain cortex. These results strongly suggest that the barrier function of the BRB is regulated by GDNF and NTN secreted from glial cells, like the BBB.

Animals↗
PubMed2000

In vivo electron spin resonance assessment of decay constant of nitroxyl radical in selenium-deficient rat.

In vivo reducing capacity and cytosolic glutathione peroxidase (GSH-Px) activity in liver homogenate were evaluated in 6 weeks old Se-deficient and normal rats. GSH-Px was significantly lower in Se-deficient rats than in normal rats. In vivo reducing capacity in head and liver parts, estimated from in vivo signal decay of a nitroxyl spin probe using a low frequency (300 MHz) ESR spectrometer, was significantly decreased in Se-deficient rats, suggesting a decrease of antioxidant capacity in Se-deficient rats.

Animals↗
PubMed2000

Proficient repair of potentially lethal damage sensitive to hypertonic treatment in osteosarcoma cells.

Fast-repairing potentially lethal damage (PLD) in seven osteosarcoma cell lines was analyzed after treatment with a hypertonic 0.5 M NaCl solution for 20 min and compared to that in seven human fibroblast strains. Fixation of PLD after exposure to ionizing radiation was observed without exception in both the osteosarcoma cells and the fibroblast strains. The percentages by which the D(o)'s of the osteosarcoma cells decreased were significantly higher than the percentage decreases in the C(o)'s of the fibroblast strains (P < 0.01). Hypertonic treatment resulted in radiosensitization due to fixation of PLD in all of the osteosarcoma cell lines, demonstrating that osteosarcoma cells can repair PLD better than normal fibroblast cells. The radiobiological response of the osteosarcoma cells, with enhanced killing after hypertonic treatment, was similar to that of normal untreated fibroblast cells.

Bone Neoplasms↗