Biomedical subjects

H Ohshima

Publications and source records attributed to H Ohshima.

At least 19 recordsLinked to original sources

PubMed2001

Suppression of intestinal polyposis in Apc(Min/+) mice by inhibiting nitric oxide production.

Inducible nitric oxide synthase (iNOS) was shown to be expressed in normal mucosa and adenoma of small and large intestines of Apc(Min/+) mice by reverse transcription-PCR and immunohistochemistry. Administration of the iNOS inhibitor aminoguanidine (1.5 g/liter) in drinking water or an L-arginine-deficient diet to Apc(Min/+) mice resulted in a significant decrease in adenoma development in the small but not the large intestine. Similarly, iNOS-gene knockout Apc(Min/+) mice (Apc(Min/+) iNOS(-/-) or Apc(Min/+) iNOS(-/+)) developed significantly fewer adenomas in both small and large intestines than Apc(Min/+) iNOS(+/+) mice. These results suggest that iNOS-selective inhibitors could be used as a potential chemopreventive agent for colorectal cancers.

Adenoma↗

PubMed2001

Chlorination of guanosine and other nucleosides by hypochlorous acid and myeloperoxidase of activated human neutrophils. Catalysis by nicotine and trimethylamine.

Activated human neutrophils secrete myeloperoxidase, which generates HOCl from H2O2 and Cl(-). We have found that various (2'-deoxy)nucleosides react with HOCl to form chlorinated (2'-deoxy)nucleosides, including novel 8-chloro(2'-deoxy)guanosine, 5-chloro(2'-deoxy)cytidine, and 8-chloro(2'-deoxy)adenosine formed in yields of 1.6, 1.6, and 0.2%, respectively, when 0.5 mM nucleoside reacted with 0.5 mM HOCl at pH 7.4. The relative chlorination, oxidation, and nitration activities of HOCl, myeloperoxidase, and activated human neutrophils in the presence and absence of nitrite were studied by analyzing 8-chloro-, 8-oxo-7,8-dihydro-, and 8-nitro-guanosine, respectively, using guanosine as a probe. 8-Chloroguanosine was always more easily formed than 8-oxo-7,8-dihydro- or 8-nitro-guanosine. Using electrospray ionization tandem mass spectrometry, we show that several chlorinated nucleosides including 8-chloro(2'-deoxy)guanosine are formed following exposure of isolated DNA or RNA to HOCl. Micromolar concentrations of tertiary amines such as nicotine and trimethylamine dramatically enhanced chlorination of free (2'-deoxy)nucleosides and nucleosides in RNA by HOCl. As the G-463A polymorphism of the MPO gene, which strongly reduces myeloperoxidase mRNA expression, is associated with a reduced risk of lung cancer, chlorination damage of DNA /RNA and nucleosides by myeloperoxidase and its enhancement by nicotine may be important in the pathophysiology of human diseases associated with tobacco habits.

Animals↗

PubMed2001

Immunocytochemical detection of superoxide dismutases (SODs) in the periodontal Ruffini endings of the rat incisor.

The expression of immunoreactivities for superoxide dismutases (SODs), Mn-SOD and Cu/Zn-SOD, was immunohistochemically investigated in the lingual periodontal ligament and toe pads of adult rats. Immunocytochemistry for SODs revealed that the axon terminals of both the periodontal Ruffini endings and cutaneous Meissner's corpuscles showed mitochondrial Mn-SOD immunoreactivity, but not cytosolic Cu/Zn-SOD immunoreactivity, indicating Mn-SOD is a useful marker for identifying the mechanoreceptors. It is likely that Mn-SOD in the axon terminals of mechanoreceptors exerts protective action against nerve injury and neuronal death under severe conditions, serving to scavenge free radicals from the axon terminals.

Animals↗

PubMed2001

Nitric oxide prevents gamma-radiation-induced cell cycle arrest by impairing p53 function in MCF-7 cells.

We previously reported that nitric oxide (NO) released from S-nitrosoglutathione induces conformational change of the p53 tumor-suppressor protein that impairs its DNA-binding activity in vitro. We now demonstrate that MCF-7 cells preincubated in the presence of 0.5-1 mM S-nitrosoglutathione for 4 h before gamma-irradiation failed to arrest in the G1 phase of the cell cycle, whereas those gamma-irradiated without S-nitrosoglutathione exhibited a normal cell cycle arrest. The S-nitrosoglutathione-treated cells did not express the p53 target gene p21(waf-1) after gamma-irradiation, although p21(waf-1) was strongly expressed in cells irradiated in the absence of S-nitrosoglutathione. These results strongly suggest that NO impairs the function of p53 possibly via conformational change and/or amino acid modifications. On the other hand, cells incubated for 16 h in the presence of 1 mM S-nitrosoglutathione underwent apoptosis with accumulation of the pro-apoptotic protein Bax. This Bax accumulation, however, was shown to occur via a p53-independent pathway.

Apoptosis↗

PubMed2001

Amelioration of experimental autoimmune encephalomyelitis with anti-OX40 ligand monoclonal antibody: a critical role for OX40 ligand in migration, but not development, of pathogenic T cells.

OX40 (CD134) and its ligand (OX40L) have been implicated in T cell activation and migration. In this study, we examined the contribution of these molecules to the pathogenesis of experimental autoimmune encephalomyelitis (EAE) by administering a neutralizing mAb against murine OX40L (RM134L) to proteolipid protein (139-151) peptide-induced EAE in SJL mice. Administration of RM134L effectively ameliorated the disease in both actively induced and adoptively transferred EAE models. Histological examination showed that the RM134L treatment greatly reduced mononuclear cell infiltration into the spinal cord. The RM134L treatment did not inhibit the development of pathogenic T cells, given that proliferative response and IFN-gamma production by draining lymph node cells were not reduced or rather enhanced upon restimulation with proteolipid protein (139-151) in vitro, and these cells effectively transferred EAE to naive SJL mice. Flow cytometric analyses showed that the RM134L treatment inhibited the accumulation of OX40-expressing CD4(+) T cells and the migration of adoptively transferred CD4(+) T cells in the spinal cord. Immunohistochemical staining showed that OX40L was most prominently expressed on endothelial cells in the inflamed spinal cord. These results suggest that the OX40/OX40L interaction plays a critical role for the migration of pathogenic T cells into the CNS in the pathogenesis of EAE.

Adoptive Transfer↗

PubMed2001

Nitrated and oxidized plasma proteins in smokers and lung cancer patients.

Cigarette smoking is a cause of lung cancer and other respiratory diseases. Oxidants either present in cigarette smoke and/or formed in the lung of smokers may trigger oxidative and nitrative damage to DNA and cellular components, contributing to carcinogenesis. We have used immunodot and Western blot analyses to measure nitrated (nitrotyrosine-containing) and oxidized (carbonyl-containing) proteins in plasma samples collected from 52 lung cancer patients and 43 control subjects (heavy and light smokers, nonsmokers with or without exposure to environmental tobacco smoke). The levels of nitrated proteins were significantly higher in lung cancer patients than in controls (P = 0.003). On the other hand, the levels of oxidized proteins were significantly higher in smokers than in nonsmokers (P < 0.001). Western-blot analyses showed the presence of two to five nitrated proteins and one oxidized protein. Using immunoprecipitation and Western-blot analyses with eight different antibodies against human plasma proteins, we identified fibrinogen, transferrin, plasminogen, and ceruloplasmin as nitrated proteins and fibrinogen as the only oxidized protein present in human plasma of lung cancer patients and smokers. Our results indicate that cigarette smoking increases oxidative stress and that during lung cancer development, formation of reactive nitrogen species results in nitration and oxidation of plasma proteins.

Aged↗

PubMed2001

Dynamic Electrophoretic Mobility of a Soft Particle.

A theory of the dynamic electrophoretic mobility of a spherical soft particle (that is, a polyelectrolyte-coated spherical particle) in an oscillating electric field is presented. In the absence of the polyelectrolyte layer a spherical soft particle becomes a spherical hard particle, while in the absence of the particle core it tends to a spherical polyelectrolyte. The present theory thus covers two extreme cases, that is, dynamic electrophoresis of hard particles and that of spherical polyelectrolytes. Simple analytic mobility expressions are derived. It is shown how the dynamic electrophoretic mobility of a soft particle depends on the volume charge density distributed in the polyelectrolyte layer, on the frictional coefficient characterizing the frictional forces exerted by the polymer segments on the liquid flow in the polyelectrolyte layer, on the particle size, and on the frequency of the applied oscillating electric field. Copyright 2001 Academic Press.

Journal Article↗

PubMed2001

Curvature elasticity of multilamellar lipid bilayers close to the chain-melting transition.

We directly measured curvature elasticity of dipalmitoylphosphatidylcholine multilamellar bilayers close to the chain-melting transition using the method of electric-field-induced bending deformation of the cylindrical tubes. The result shows that the bending modulus, kappa(c), decreases remarkably at temperatures close to the melting transition temperature. This reflects a softening of the bilayer resulted from the area fluctuations as predicted theoretically. However, the decrease of kappa(c) near the transition is far smaller than that predicted. This is due to the experimental method and the narrow transition width of the multilamellar bilayers. Nevertheless, the result obtained gives direct evidence of the kappa(c) reduction predicted for multilamellar membranes in the transition regime. Below about 41 degrees C, almost of all cylindrical tubes cannot response to the electric field, indicating a very large bending rigidity.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2001

Preparation and properties of thermosensitive hydrogel microcapsules.

Temperature-sensitive hydrophilic gel microcapsules have been newly prepared. That is, poly (L-lysineisopropylamide-terephthalic acid) microcapsules containing water have been obtained by an interfacial polymerization at a water/oil interface between L-lysineisopropylamide and terephthaloyldichloride. The microcapsule changes its size between 33 and 35 degrees C. Under 33 degrees C, the microcapsules are fully spherical and can be redispersed in distilled water, while are aggregated above 35 degrees C. The microcapsules, which are observed to show aggregation above 33 degrees C, can be redispersed by decreasing temperature within a few second. The thermosensitive morphological changes of the microcapsules are thus reversible. Also, it has been shown that the permeability of sodium chloride through the microcapsule membrane changes remarkably between 33 and 35 degrees C, while it is kept almost constant independent of temperature between 25 and 33 degrees C or between 35 and 55 degrees C. The permeability of solutes is higher under 33 degrees C than that above 35 degrees C. Such thermosensitive properties result from the fact that the polymer membrane has isopropylamide groups. That is, L-lysineisopropylamide has a chemical structure similar to N-isopropylacrylamide, the polymer of which, poly (N-isopropylacrylamide), is a thermosensitive hydrogel having its phase transition temperature around 33 degrees C.

Journal Article↗

PubMed2001

Effects of thermosensitivity of poly (N-isopropylacrylamide) hydrogel upon the duration of a lag phase at the beginning of drug release from the hydrogel.

The release rates of three kinds of drugs, with different charges, from poly (N-isopropylacrylamide) hydrogels were studied. The release rate was observed to be temperature dependent for the types of drug. When the temperature was lower than the phase transition temperature, the release rate was higher at lower temperatures and increased as the temperature rose. The amount of drugs released from a poly (N-isopropylacrylamide) hydrogel disk was plotted against the square root of time. It was found that the amount of drugs released was proportional to the square root of time over a certain time interval. A lag phase was observed before the amount of drug released became proportional to the square root of time. The longest time lag was observed at the phase transition temperature of poly (N-isopropylacrylamide); LCST (33 degrees C). This suggests that the penetration rate of water into the hydrogels is lowest at the phase transition temperature and drastically changes around it. The release rates of drugs was also affected by the charges of the drug molecules. This may be caused by the interaction of drug molecules with polymer chains. When anionic drugs are released, the electrostatic repulsion seems to act between polymer chains and drug molecules. Therefore, the lag phase observed at the beginning of the release of anionic drugs was shorter, as compared with other kinds of drugs at any temperatures between 25 and 40 degrees C. On the other hand, when cationic drugs are released, the time lag was longer at temperatures higher than 33 degrees C as compared with the time lag at lower temperatures. At temperatures higher than 33 degrees C, drugs are released from the surface skin layer of the hydrogel where water molecules are less mobile than those in bulk distilled water. The drug release thus shows a long lag phase.

Journal Article↗

PubMed2001

Aggregation behavior of poly(N-isopropylacrylamide) microspheres.

Electrophoretic mobility and aggregation in suspensions of three types of microspheres (Ms 1, Ms 2 and Ms 3) are studied at different pH, ionic strengths and temperatures of the medium. Here Ms 1 is a core particle composed of poly(N-isopropylacrylamide-co-styrene). Ms 2 is a core-shell microsphere consisting of Ms 1 as the particle core covered with a surface layer of poly(N-isopropylacrylamide) hydrogel. Ms 3 is also a core-shell microsphere composed of MS-1 covered with a surface layer of poly(N-isopropylacrylamide-co-acrylic acid) hydrogel. The charge density zN and the softness parameter 1/lambda of the microspheres were obtained from the electrophoretic mobility data on the basis of an electrokinetic theory of soft particles. It is shown that when zN is large, suspensions of microspheres are always stable, showing no aggregation. When zN is small, the suspensions are stable for large 1/lambda but show strong aggregation for small 1/lambda.

Journal Article↗

PubMed2001

Design of a rate- and time-programming drug release device using a hydrogel: pulsatile drug release from kappa-carrageenan hydrogel device by surface erosion of the hydrogel.

We have found that a repetitive pulsatile drug release with a certain time interval is observed from a monolithic hydrogel device by surface erosion of the hydrogel. As a model system of pulsatile drug release, dibucaine hydrochloride and kappa-carrageenan hydrogel were chosen as a drug and a device, respectively. Electrostatic interactions between dibucaine hydrochloride and kappa-carrageenan polymer segments are strong, since dibucaine hydrochloride is positively charged and each disaccharide repeating unit of kappa-carrageenan chains has one sulfate group. Dibucaine hydrochloride was loaded into the hydrogel by immersing dry kappa-carrageenan hydrogel disks in a dibucaine hydrochloride solution for 24 h. The pulsed release of dibucaine hydrochloride from the device was observed every 50 min between 30 and 250 min after the release starts. The weight of kappa-carrageenan hydrogel decreases in an oscillatory manner with time in distilled water. The oscillatory changes observed in the hydrogel weight in distilled water are considered to be caused by influx and efflux of water molecules into and from the surface and core of the hydrogel and by polymer liberation from the hydrogel. This phenomenon was well explained by our kinetic model [Colloids and Surfaces B 8 (1996) 93-100]. The time interval between pulses observed in drug release coincides with that observed in the oscillatory weight change of the hydrogel. From these, it was concluded that the pulsatile release of dibucaine hydrochloride from the device was caused by the pulsatile liberation of swollen kappa-carrageenan hydrogel from the surface of the device.

Journal Article↗

PubMed2001

Formation of spiroiminodihydantoin nucleoside by reaction of 8-oxo-7,8-dihydro-2'-deoxyguanosine with hypochlorous acid or a myeloperoxidase-H(2)O(2)-Cl(-) system.

Hypochlorous acid (HOCl), generated by myeloperoxidase from H(2)O(2) and Cl(-), is a strong chlorinating and oxidizing agent, playing an important role in host defense and inflammatory tissue injury. As several recent studies have shown that various oxidizing agents including peroxynitrite and singlet oxygen react readily with 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) to yield further oxidized products, we have studied the reaction of 8-oxodGuo with reagent HOCl and with a myeloperoxidase-H(2)O(2)-Cl(-) system. When 1 mM 8-oxodGuo was reacted with 0.5 mM HOCl at pH 7.4 and 37 degrees C, two major products were formed. They were identified as the diastereomers of spiroiminodihydantoin deoxyribonucleoside (dSph) on the basis of their identical ESI-MS and UV spectra and HPLC retention times with those of the major reaction products which were reported to be formed in other oxidation systems including potassium monopersulfate plus cobalt (II) chloride, peroxynitrite plus thiol, and type II photosensitization. Under the above reaction conditions, the yield of the diastereomers of dSph was 0.38 mM, with 0.57 mM 8-oxodGuo remaining unreacted. Since the presence of 50% D(2)O, 10 mM sodium azide, or 2% ethanol did not affect the yield of the products, involvement of singlet oxygen and hydroxyl radical in the formation of dSph from 8-oxodGuo with HOCl was ruled out. A 1000-fold excess of dGuo did not inhibit the reaction of 8-oxodGuo with HOCl, indicating that 8-oxodGuo reacts more readily than dGuo with HOCl. dSph was also formed by reaction of 8-oxodGuo with myeloperoxidase in the presence of H(2)O(2) and Cl(-). Our results suggest that formation of dSph from 8-oxodGuo is mediated, possibly via an addition of Cl(+) to, or two-electron oxidation of 8-oxodGuo, with HOCl or the myeloperoxidase-H(2)O(2)-Cl(-) system.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Increased oxidative and nitrative stress in human stomach associated with cagA+ Helicobacter pylori infection and inflammation.

In order to study the role of Helicobacter pylori infection in gastric carcinogenesis, we have measured oxidized (carbonyls) and nitrated (nitrotyrosine-containing) proteins as markers for oxidative and nitrative stress in 216 human gastric biopsies using dot and western immunoblots and correlated the results with H. pylori, cagA status, expression of interleukin-8 and inducible nitric oxide synthase (iNOS) mRNAs, and gastric pathology. Higher levels of both oxidized and nitrated proteins were found in patients with either chronic gastritis or duodenal ulcer than in those with normal mucosa. The levels of modified proteins were significantly higher in inflamed samples infected with H. pylori, especially cagA+ strains, and in those with expression of interleukin-8 and iNOS mRNAs than in those negative for these parameters. These results indicate that infection with cagA+ H. pylori induces significant oxidative and nitrative stress in stomach mucosa, contributing to the pathogenesis of H. pylori-associated gastroduodenal diseases.

Antigens, Bacterial↗

PubMed2001

Melatonin therapy for REM sleep behavior disorder.

Rapid eye movement sleep behavior disorder (RBD) is a parasomnia with clinical symptoms that include punching, kicking, yelling and leaping out of bed in sleep. Polysomnographic (PSG) finding showed REM sleep without muscle atonia. Clonazepam is generally used for treating RBD symptoms but melatonin was reported to be effective so we reconfirmed the effect of melatonin on RBD patients in the present study. We used melatonin (3-9 mg/day) which could ameliorate problem sleep behaviors remarkably, as well as %tonic activity in PSG variables. In the present study, melatonin was reconfirmed to be effective in RBD symptoms, especially for patients with low melatonin secretion, while its mechanism was not clearly known in the present study.

Electromyography↗

PubMed2001

Inverse correlation between alcohol consumption and lymphocyte levels of 8-hydroxydeoxyguanosine in humans.

In a cross-sectional study of 115 premenopausal non-smoking women, we examined the relationship between lymphocyte levels of 8-hydroxy-2'-deoxyguanosine (8-oxodGuo) and habitual alcohol consumption. The study was conducted in four different regions of Europe, including Potsdam (Germany), Turin (Italy), Malmö (Sweden) and Granada (Spain). Mean 8-oxodGuo levels differed significantly across study centres (P = 0.001), with the highest levels in Granada [2.17 8-oxodGuox10(-6) 2'-deoxyguanosine (95% confidence interval 1.27-4.40)] and lowest levels in Turin [1.19 (0.36-4.29)]. Mean levels of total alcohol intake and of types of alcoholic beverages consumed (wine, fortified wines, beer and cider) also differed across the study centres (P < 0.05), with the highest total alcohol consumption in Turin, and the lowest intake in GRANADA: When combining all the data, but adjusting for study centre, individual 8-oxodGuo level correlated inversely with alcohol intake. This inverse association remained unaltered after further adjustment for Quetelet Index, fruit and vegetable consumption, and plasma carotenoid levels. Furthermore, the inverse association was also observed for each of the study centres separately, and for different beverage types, with the exception of Granada, where the majority of women were non-drinkers and where alcohol intakes were also very low for the consumers. Finally, on a group level, mean levels of 8-oxodGuo and alcohol intake were also inversely associated between the four study centres. The finding of a relationship between alcohol consumption and 8-oxodGuo in lymphocytes was unexpected and not based on a prior hypothesis. This finding consequently requires confirmation from a randomized intervention study.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Helicobacter pylori eradication attenuates oxidative stress in human gastric mucosa.

OBJECTIVE: Helicobacter pylori infection causes gastric diseases, but the responsible mechanisms are not completely understood. They can involve DNA and tissue damage induced by reactive oxygen and nitrogen species. Our aim is to investigate the effects of bacterial eradication on oxidative stress by measuring changes of relevant markers. METHODS: Antral biopsies were obtained from 34 patients with chronic atrophic gastritis and peptic ulcer disease before and after bacterial eradication. The expression of inducible nitric oxide synthase (iNOS) and levels of nitrotyrosine (NTYR) and 8-hydroxy-2'-deoxyguanosine were assessed immunohistochemically as markers of nitric oxide (NO) production and of damage to proteins and DNA, respectively. RESULTS: Before treatment, the percentages of patients with staining were: 56 for iNOS in inflammatory cells, 79 and 61 for NTYR and 8-hydroxy-2'-deoxyguanosine in foveolar cells, respectively, and 82 for 8-hydroxy-2'-deoxyguanosine in lymphoid follicles. NTYR staining was associated with the intensity of inflammation (p = 0.04) and gastritis activity (p = 0.07). The prevalence of 8-hydroxy-2'-deoxyguanosine tended to be associated with that of NTYR. After successful H. pylori eradication, the prevalence of iNOS and NTYR (in mild gastritis) staining decreased (p < 0.001 and p < 0.06, respectively). 8-Hydroxy-2'-deoxyguanosine staining disappeared in 24% of cases but appeared in 18% of previously negative cases despite eradication. CONCLUSION: Targets of oxidative stress associated with H. pylori infection are inflammatory and deep foveolar cells and lymphoid follicles. This is the first report of 8-hydroxy-2'-deoxyguanosine localization in gastric mucosa. Oxidative stress is reduced by bacterial eradication in the first stages of mild gastritis. Moderate-severe gastritis may be a step that is reversible for iNOS, but partly irreversible for NTYR and 8-hydroxy-2'-deoxyguanosine.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Possible role of heat shock protein (Hsp) 25 in the enamel organ during amelogenesis in the rat molar.

The postnatal expression of heat shock protein (Hsp) 25 during the amelogenesis of rat molars was investigated by immunocytochemistry and confocal microscopy. The localization pattern of Hsp 25-immunoreactivity in the inner enamel epithelium and ameloblast cell layer of the rat molars was almost identical to that in the rat incisors which we have previously reported: an intense Hsp25-immunoreactivity, which first appeared in the preameloblasts, was recognized in secretory ameloblasts and ruffle-ended ameloblasts with stage-specific immunointensity. Confocal microscopy with Hsp 25-antibody and rhodamine-labeled phalloidin clearly demonstrated the co-localization of Hsp 25 and actin filaments in the ameloblast layer, supporting our hypothesis that this molecule might serve to reinforce the ameloblast layer during enamel formation as well as the formation and maintenance of the ruffled border in ruffle-ended ameloblasts. Interestingly, the enamel free area cells, which essentially lack the ability for enamel formation, showed the Hsp 25-immunoreactivity during 4-11 days when they developed a ruffled border, but decreased in that immunoreactivity after postnatal 15 days following apoptosis. Since Hsp 25 has been shown to be a specific inhibitor of apoptosis, the enamel-free area cells contribute to determine the outline of dentin at the cusped area. These data support our previous hypothesis on the diverse functions of Hsp 25 in amelogenesis.

Actin Cytoskeleton↗