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Biomedical subjects

H Ohshima

Publications and source records attributed to H Ohshima.

At least 91 records · Page 5Linked to original sources
PubMed1999

[Preoperative autologous blood donation in coronary artery bypass grafting in elderly patients].

Allogeneic blood transfusion still carries risks of transfusion reaction and infection. We examined the effect of a preoperative autologous blood donation (800-1,200 g) by subcutaneous epoetin alpha injection on a series of patients undergoing elective coronary artery bypass grafting (CABG). CABG was being performed with increased frequency in elderly patients. We have performed CABG in 18 patients over 65 years of age (elderly group). These patients were compared with 20 patients under 64 years of age (younger group). Postoperative bleeding and allogeneic blood transfusion were significantly larger in quantity in the elderly group than the younger group (p < 0.05). The incidence of allogeneic blood usage was significantly higher in the elderly group than the younger group (p < 0.05). Therefore, a preoperative autologous blood donation in CABG was considered to be not so effective for saving allogeneic blood transfusion and preventing transfusion reaction or infection in elderly patients.

Aged↗
PubMed1998

Sedimentation Potential in a Concentrated Suspension of Spherical Colloidal Particles.

A theory of sedimentation in a concentrated suspension of spherical colloidal particles proposed by Levine et al. (J. Colloid Interface Sci. 57, 424 (1976)) is further developed to derive a simple convenient expression for the sedimentation potential applicable for low zeta potentials and nonoverlapping electrical double layers of adjacent particles. An Onsager relation between the sedimentation potential and electrophoretic mobility of spherical colloidal particles in concentrated suspensions is derived. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Induced potential model for muscular contraction mechanism, including two attached states of myosin head.

The model for myosin head motion along an actin filament as proposed by Mitsui & Chiba [(1996). J. theor. Biol. 182, 147-159] is here modified so that it can explain the isometric tension and isotonic velocity transients having the same parameter values as the stationary filament sliding. The modified model differs in that a myosin head forms a complex with two actin molecules in an actin filament and has two attached states in the complex instead of three. Thus an incremental step in the myosin head motion is equal to the F-actin monomer repeat (5.46 nm). Muscle properties concerning the stationary filament sliding are calculated with new parameters in a manner similar to that of Mitsui-Chiba, with the results being qualitatively similar to theirs. In studying the transient phenomena, a quantitative expression is given for the potential energy of the myosin head in the complex, and two rate constants are applied to the kinetics of the head. The time course of tension recovery after a quick length change is determined by calculating the statistical distribution of the head in the two attached states, which conforms to experimental observations by Ford et al. [(1977). J. Physiol. 269, 441-515]. The tension variations T1/T0 and T2/T0 calculated with parameters determined from the analysis of stationary filament slidings are in fairly good agreement with the experimental data by Ford et al. The model suggests that a large fluctuation exists in the relative position between the actin and myosin filaments even when the load on a muscle is kept constant. Taking this fluctuation into account explains the characteristics of the isotonic velocity transient observed by Civan & Podolsky.

Actins↗
PubMed1998

Cysteine oxidation in the mitogenic S100B protein leads to changes in phosphorylation by catalytic CKII-alpha subunit.

The glial-derived calcium-binding protein S100B can be secreted to act as a neurotrophic factor or a mitogen, stimulating proliferation of glial cells. The extracellular S100B activities rely on the oxidation of the protein cysteine residues (Kligman, D., and Marshak, D. R. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 7136-7139; Winningham-Major, F., Staecker, J. L., Barger, S. W., Coats, S., and Van Eldik, L. J. (1989) J. Cell Biol. 109, 3063-3071). Here we show that oxidation of the S100B cysteine residues, Cys-68 and Cys-84, induces a conformational change in the protein structure, unmasking a canonical CKII phosphorylation site located within the typical EF-hand calcium-binding site IIbeta. Intrasubunit disulfide-bridged S100B monomer and disulfide-bonded S100B dimer are phosphorylated by the catalytic CKII-alpha subunit on Ser-62 with a Km of 0.5 microM and a Vmax of 10 pmol/min/100 pmol of S100B. Oxidized S100B is the best in vitro CKII-alpha substrate identified so far. Next we show that intrasubunit disulfide-bridged S100B monomer is the most potent S100B species to stimulate [3H]thymidine uptake by C6 glial cells in culture. In addition, the phosphorylated intrasubunit disulfide-bridged S100B monomer retains apparent mitogenic activity toward C6 glial cells, and hence, 32P-labeled S100B should be a useful probe for characterizing the mechanisms by which extracellular oxidized S100B functions. Finally, we show that formation of intrasubunit disulfide-bridged S100B monomer is stimulated by peroxynitrite anion, suggesting that production of mitogenic S100B species could be enhanced in neuropathology associated with peroxynitrite anion production.

Amino Acid Sequence↗
PubMed1998

Size Dependence of Polymer Composition in the Surface Layer of Poly(acrylamide-co-acrylic acid) Hydrogel Microspheres

Poly(acrylamide-co-acrylic acid) hydrogel microspheres of four different average sizes were prepared using a membrane emulsification technique. These four kinds of microspheres had average diameters of 1.35, 2.33, 3.09, and 7.43 &mgr;m in distilled water and were all fairly monodisperse. Their surface properties were studied by measuring the electrophoretic mobility of the microspheres. The mobility values were negative at pH 7.4 with the ionic strengths between 0.005 and 0.154 at 25&deg;C. More negative mobility values were obtained with smaller microspheres than the larger ones. By analyzing the data with an electrokinetic theory for "soft" surfaces, it was found that smaller microspheres have higher surface charge density than the larger ones, although all kinds of microspheres were prepared from monomer solutions with the same monomer composition. The observed size dependence of the electrophoretic mobility suggests that copolymerization of acrylamide monomers and acrylic acid monomers does not proceed homogeneously within a microsphere. That is, charged acrylic acid monomers have a tendency to be localized in the microsphere core region, whereby the surface region of microspheres becomes poor in charges, reducing the mobility of larger microspheres. This is not the case for smaller microspheres, so that their mobility becomes more negative. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗
PubMed1998

Synergistic induction of DNA strand breakage by catechol-estrogen and nitric oxide: implications for hormonal carcinogenesis.

Estrogen is a known risk factor for human breast cancer, although the mechanism by which estrogens induce cancer remains unestablished. We have demonstrated that DNA strand breakage is induced synergistically when pBR322 plasmid DNA is incubated in the presence of both a nitric oxide (NO)-releasing compound (diethylamine NONOate, etc.) and a catechol-estrogen (2- or 4-hydroxyestradiol or -hydroxyestrone). Either the NO-releasing compound or the catechol-estrogen alone induced much fewer strand breaks. Estradiol, estrone, O-methylated catechol-estrogens, and diethylstilbestrol did not exert such DNA damaging effects. Strand breakage induced by NO plus 2- or 4-hydroxyestradiol was inhibited by carboxy-PTIO (an NO-trapping agent) and, to a lesser extent, by superoxide dismutase. Antioxidants (e.g., N-acetylcysteine, ascorbate), but not HO. scavengers, exhibited inhibitory effects. A possible mechanism for this strand breakage would be: (1) NO mediates conversion of catechol-estrogens to quinones, (2) the quinone/hydroquinone redox system produces O2.-, and (3) O2.- reacts with NO to form peroxynitrite, which causes DNA strand breaks. Our results imply that interaction of catechol-estrogens and NO, both known to be formed in human breast and uterus, leads to production of a potent oxidant(s), which could cause damage in cells and DNA, thus playing an important role in hormonal carcinogenesis.

Antioxidants↗
PubMed1998

Three-dimensional direction and interrelationship of prisms in cuspal and cervical enamel of dog tooth.

The three-dimensional architecture of enamel prisms was examined in cuspal enamel and compared with that in cervical enamel by light and electron microscopy as well as computer-assisted reconstruction using the developing enamel of several dog teeth. Dog tooth enamel consists of two groups of alternately arranged enamel prisms oriented in opposite sideward directions basically forming thick horizontal rings, partly branching off from the stem. Along a 8-10 enamel prism-wide group, the enamel prisms emerge in parallel tilting uniformly to the same sideward direction. In cervices, groups of enamel prisms are arranged nearly in parallel displaying a regular arrangement of prisms. Approaching the cusp of tooth, the groups of enamel prisms fuse to a concentric cusp-centered arrangement and the prisms exhibit no periodic arrangement as shown in the cervical enamel. It is suggested that the three-dimensional structure of enamel becomes complicated close to the cusp, contributing to the chewing stress of tooth.

Ameloblasts↗
PubMed1998

Cytochrome oxidase activity in the enamel organ during amelogenesis in rat incisors.

Cytochrome oxidase (CO), one of the membrane-bound mitochondrial enzymes involved in oxidative phosphorylation, reflects the functional activity of mitochondria. Mitochondria in the enamel organ show drastic changes in localization during amelogenesis (Smith. INSERM, 1984;125:273-282). In understanding the functional aspects of the enamel organ, it is essential that one knows the exact CO activity in the respective mitochondria. The present study examines the CO activity of mitochondria in the enamel organ of rat incisors throughout the various stages of amelogenesis using light and transmission electron microscopy. CO activity was examined histochemically according to Seligman et al. (J. Cell. Biol., 1968;38:1-14) in decalcified sections of the upper and lower incisors of the rat. In the secretory stage, half of the mitochondria in the ameloblasts accumulated in the infranuclear region were reactive for CO. Both the population and CO activity of the infranuclear mitochondria of ameloblasts decreased significantly in the later stage where the enamel matrix secretion was almost complete. The CO-reactive mitochondria in the cells of the stratum intermedium (SI) gradually increased in number throughout the secretory stage. In the maturation stage, the ameloblasts contained intensively CO-reactive giant mitochondria in the proximal region and regular sized ones in the distal cytoplasm that were mostly devoid of detectable CO reactivity. The proportion of CO-reactive mitochondria in the supranuclear region and the population of mitochondria in the infranuclear regions of the smooth-ended ameloblasts were significantly higher as compared with the respective values in the ruffle-ended ameloblasts. In the late stages of enamel maturation, ameloblasts containing a large number of ferritin-filled pigment vesicles possessed numerous CO-reactive mitochondria between those vesicles in the supranuclear region, implicating an active role of the ameloblasts in iron transfer into the maturing enamel. The papillary layer cells possessed numerous intensively CO-reactive mitochondria throughout the maturation stage. A stage-related variation in the localization of CO-reactive mitochondria in the enamel organ of rat incisors was quantitatively demonstrated. It is conceivable that maturation stage ameloblasts form a functional unit with the papillary layer cells, and operate in energy-requiring events such as active ion transport to, and water and matrix protein removal from the maturating enamel. A sign of such functional integrity among the types of the enamel organ cells (ameloblasts, cells of SI, cells of stellate reticulum, and outer enamel epithelial cells) cannot be seen in the secretory stage. The secretory ameloblasts may function in matrix formation and calcium regulation in a less cooperative manner with the other cells of the enamel organ as compared to the maturation stage ameloblasts.

Amelogenesis↗
PubMed1998

Experimental chronic infection induced in mice by Actinomyces israelii entrapped in alginate gel.

Tissue responses to experimentally induced actinomycotic lesions were investigated in mice by both light and transmission electron microscopy. Micro-organisms of Actinomyces israelii were entrapped in alginate gel and injected into the subcutaneous tissue over the periosteum of the mouse cranium. One day after the injection (initial stage), a non-stained amorphous structure was located in the core of the lesion, corresponding to the injected gel with bacteria. Numerous neutrophils surrounded the core region and phagocytized the injected complex actively. At days 3-7 (intermediate stage), the lesion became well developed. The core structure became eosinophilic and separated to form island-like structures. No lesion was recognized in the control group (gel without bacteria) until day 14. After 30 days (late stage), the lesions displayed more static features, similar to the "sulphur granules" characteristic of actinomycotic lesions. At the late stage, foamy cells increased in number and took the place of neutrophils in the alginate islands. By transmission electron microscopy these foamy cells were seen to be filled with lysosomal vesicles containing electron-dense foreign material. Thus, these cells appeared to be macrophages that had phagocytized degenerated neutrophils containing bacteria. Along with the active phagocytosis by foamy cells that progressed in the late stage, a collagenous capsule became conspicuous and separated the lesion from the intact tissue. The bacteria remained in the gel islands until at least day 60, although they considerably decreased in number with time. Serum IgG antibody titres began to rise within 24 h of the injection, reached a peak concentration at day 14 and remained a significantly high (p < 0.01, vs 0 time) until day 120. These results suggest that this animal model is useful for inducing experimental chronic infectious lesions.

Actinomyces↗
PubMed1998

Antioxidant and pro-oxidant actions of flavonoids: effects on DNA damage induced by nitric oxide, peroxynitrite and nitroxyl anion.

Antioxidant and pro-oxidant activities of flavonoids have been reported. We have studied the effects of 18 flavonoids and related phenolic compounds on DNA damage induced by nitric oxide (NO), peroxynitrite, and nitroxyl anion (NO-). Similarly to our previous findings with catecholamines and catechol-estrogens, DNA single-strand breakage was induced synergistically when pBR322 plasmid was incubated in the presence of an NO-releasing compound (diethylamine NONOate) and a flavonoid having an ortho-trihydroxyl group in either the B ring (e.g., epigallocatechin gallate) or the A ring (e.g., quercetagetin). Either NO or any of the above flavonoids alone did not induce strand breakage significantly. However, most of the tested flavonoids inhibited the peroxynitrite-mediated formation of 8-nitroguanine in calf-thymus DNA, measured by a new HPLC-electrochemical detection method, as well as the peroxynitrite-induced strand breakage. NO- generated from Angeli's salt caused DNA strand breakage, which was also inhibited by flavonoids but at only high concentrations. On the basis of these findings, we propose that NO- and/or peroxynitrite could be responsible for DNA strand breakage induced by NO and a flavonoid having an ortho-trihydroxyl group. Our results indicate that flavonoids have antioxidant properties, but some act as pro-oxidants in the presence of NO.

Antioxidants↗
PubMed1998

Relationships between the synthesis of N-nitrosodimethylamine and immune responses to chronic infection with the carcinogenic parasite, Opisthorchis viverrini, in men.

This study investigated the relationship between immune responses to infection with the liver fluke, Opisthorchis viverrini, and the synthesis of the carcinogen, N-nitrosodimethylamine (NDMA) in humans. It also examined associations between synthesis of nitric oxide (NO) and nitrosation of amines, in vivo. Antibody and T cell responses to fluke antigens and post-alcohol urinary NDMA excretion were assessed among three groups of 40-50 men with no, moderate and heavy liver fluke infection. Markers of NO synthesis (nitrate, nitrite) and nitrosation (nitrosamino acids) were also measured in biological fluids. Assessments were carried out under controlled conditions which minimised intake of exogenous nitrate and nitrite and were carried out at two time points, namely before and 4 months after elimination of the infection with praziquantel treatment. No statistically significant variation was observed in the amount of NDMA excreted between the 3 groups. However, during active infection, a strong negative association was observed between in vitro lymphoproliferative responses to some liver fluke antigens and NDMA excretion. After treatment this association was reduced. Multivariate statistical models revealed a highly significant relationship between NDMA levels and urinary nitrate, stimulation indices for two T cell responses to two parasite antigens (MW 37 kDa and 110 kDa) and gall bladder dimensions. NDMA levels after treatment were best described by the ratio between parasite-specific IgG2 and IgE, background levels of T cell proliferation, a urinary marker of nitrosation (N-nitrosothioproline) and usual level of alcohol consumption. These results suggest that individual background immunologic activity, parasite-specific responses and/or parasite products and NO synthesis are important determinants of endogenous generation of nitrosamines in O. viverrini-infected humans.

Adult↗
PubMed1998

Inducible nitric oxide synthase, anti-oxidant enzymes and Helicobacter pylori infection in gastritis and gastric precancerous lesions in humans.

Chronic inflammation induced by Helicobacter pylori infection has been associated with an increased risk of stomach cancer. We have analysed 167 stomach biopsies from 99 patients for H. pylori infection and immunohistochemically for the expression of inducible nitric oxide synthase (iNOS), catalase and superoxide dismutases (SODs) as markers of oxidative stress. Biopsies were graded as follows on the basis of histology: normal, superficial gastritis, variable severity of atrophic gastritis with or without intestinal metaplasia, and dysplasia. iNOS was detected in inflammatory cells in all types of gastritis with or without H. pylori infection and independently of its severity. In foveolar cells, iNOS was observed in approximately 25% of all biopsies showing any type of gastritis, but in a markedly higher proportion of dysplastic samples. Catalase and Mn-type SOD in inflammatory cells and catalase in foveolar cells were more frequently observed in marked atrophic gastritis biopsies than in less severe gastritis. Individual differences were found in the expression of these enzymes within groups with the same severity of gastritis. Prolonged oxidative stress in severe gastritis and dysplasia may play an important role in gastric carcinogenesis, through increased damage of DNA and tissue by reactive oxygen and nitrogen species.

Adult↗
PubMed1998

Circadian rhythms of hormone concentrations in alcohol withdrawal.

We investigated the circadian rhythm of hormones (cortisol, melatonin) in alcoholic patients during and 1 month after alcohol withdrawal. Patients with delirium tremens had irregular serum hormone concentration rhythms during withdrawal, which normalized after the withdrawal period. Patients without delirium tremens had normal circadian rhythms even during the withdrawal period. We speculated that the disturbance of the biological oscillator, in terms of the decline of synchronizing function or the decrease in synchronizing factors, caused abnormal circadian rhythms of hormone release during delirium tremens.

Adult↗
PubMed1998

Photosensitive seizures provoked while viewing "pocket monsters," a made-for-television animation program in Japan.

PURPOSE: To describe the recent epidemic of photosensitive seizure that occurred in relation to an episode of the television animation program "Pocket Monsters," we report four patients who experienced seizures while watching the episode in question. We also report some technical aspects of the program episode. METHODS: We investigated the clinical symptoms of the four patients and performed routine EEGs with intermittent photic stimulation (IPS). If IPS provoked no photoparoxysmal response (PPR) during the routine EEG examination, a second EEG was performed with the photic stimulator placed 10 cm from the patient's eyes. In addition, we reviewed the "Pocket Monsters" episode, focusing our attention on the visual techniques used with reference to the Independent Television Commission (ITC) guidelines. RESULTS: One patient who had myoclonic jerks before the convulsion in question was diagnosed as having juvenile myoclonic epilepsy, and the diagnosis of another patient was pure photosensitive epilepsy. The remaining two patients had their first seizures, which could be occasional seizures, and we therefore could not reach a diagnosis of epilepsy. In our four patients, only one showed PPR on the routine EEG. Two patients revealed PPR on the second EEG, and the remaining patient showed no PPR. Rapid changes in color are believed to be responsible for the photosensitive seizures because all four patients had seizures at around 18:50, when seconds of deep red and bright blue flashes, alternating at a frequency of 12 Hz, were shown. CONCLUSIONS: Regulations for technical aspects of children's programming, including the use of colors, are urgently needed in Japan to prevent a repeated incident. In addition, the IPS procedure needs to be standardized, especially for patients who are suspected to have photosensitivity.

Adolescent↗
PubMed1998

Class II MHC antigen-expressing cells in the pulp tissue of human deciduous teeth prior to shedding.

The distribution and ultrastructure of the class II major histocompatibility complex (MHC) antigen-expressing cells in the pulp tissue of human deciduous teeth during the process of physiological root resorption was surveyed by histochemical and immunocytochemical methods using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. Dental pulp was found to contain numerous HLA-DR-positive cells of various shapes; those showing a dendritic appearance were located mainly in the periphery of the pulp tissue, associated closely with the odontoblasts. The immunopositive cells sometimes extended their cytoplasmic processes into the dentinal tubules and increased in number in the areas affected by dental caries, attrition or restorative procedures, implicating their role in immunosurveillance. The immunopositive cells were located consistently at the pulp-dentin border during the stage of active resorption, adjacent to the preodontoclasts or odontoclasts, and covered the exposed dentin surface after the detachment of the odontoclasts until the onset of cementum formation. These data suggest that the HLA-DR-immunopositive cells in the coronal pulp of human deciduous teeth play an inductive role in the differentiation, migration and/or activation of the odontoclasts and cementoblast-like cells during the stages of tooth resorption.

Dental Pulp↗
PubMed1998

[Cardiac surgery by the safe and easy insertion method with the J-shaped left ventricular vent catheter].

We experienced the safe and easy insertion method with the J-shaped left ventricular vent catheter. The catheter tip (about 15 cm) was vended in the J shape with the inner stainless steel introducer. This J-shaped catheter was inserted into the left atrium through the right upper pulmonary vein. Then this catheter was held vertically and only the outer silicone catheter was pushed into the left ventricle. In this method the catheter tip is turned to the front in the left atrium and inserted easily into the left ventricle along the anterior wall of the left atrium through the anterior margin of the mitral valve orifice.

Adult↗
PubMed1998

[Auditory evoked magnetic fields in patients of pure word deafness].

Auditory evoked magnetic fields (AEF) were recorded in 2 cases with pure word deafness. AEF examination were performed with a novel 129-channel vector neuromagnetic imaging system (SBI 100). The latency and the location of equivalent current dipole (ECD) of N100 m after 1,000 Hz tone burst stimulation, one of the most prominent peak of AEF, were evaluated. One patient, 59-year-old man, suffered from left putaminal hemorrhage and the other, 59-year-old man, had a history of bilateral putaminal hemorrhage. There was no N100 m detected in the left temporal lobe with the right ear stimulation in both patients. However normal N100 m was obtained in the right hemisphere with the left ear stimulation in both cases. And the position of ECD of N100 m in the right hemisphere were correctly superimposed on the Heschl gyrus in brain MRI. The pathophysiology of pure word deafness has been postulated that a disconnection between Wernicke area and bilateral auditory inputs played one of important roles in progression of pure word deafness. Because there was no pathological lesion in temporal lobe verified by MRI study in both patients, N100 m in the left could not be evoked due to interception of the auditory pathway to the Heschl gyrus, but not due to destruction of Heschl gyrus. AEF test is one of the most useful tools in order to estimate central auditory function in patients with pure word deafness.

Aphasia, Wernicke↗