Search PubMed⌕ Search

Biomedical subjects

H Ohshima

Publications and source records attributed to H Ohshima.

At least 163 records · Page 9Linked to original sources
PubMed1995

[One-stage repair of interrupted aortic arch with ventricular septal defect].

Three neonates with type A interrupted aortic arch were successfully repaired through a median sternotomy incision during profound hypothermia and circulatory arrest in the past one year. Two aortic cannulas, a small plastic one (Cardicorp) in the ascending aorta and a long one inserted through the pulmonary artery and patent ductus arteriosus into the descending aorta. Two Pacifico's venous cannulas were inserted into superior and inferior vena cavae respectively. No dissection and encircling were required around three major branches from the aortic arch and both right and left pulmonary arteries. During a cooling phase a large ventricular septal defect was closed followed by circulatory arrest. It was possible to resect a patent ductus arteriosus and mobilize the descending thoracic aorta for anastomosis to the side of the ascending aorta without removal of the aortic cannula in the aorta. New instruments and development of cardiopulmonary bypass could bring a successful one-stage repair of interrupted aortic arch with ventricular septal defect more safely and easily than before.

Aorta, Thoracic↗
PubMed1995

[Cardiac operation of the cases associated with malignant tumor].

Twelve cases of malignant tumor (mean age 64 years) underwent the cardiac operation. The procedure of cardiac operations were 10 coronary artery bypass grafting and 2 mitral valve replacement. The detail of malignant tumors were 4 gastric cancer, 3 colon cancer, 3 lung cancer, 1 esophageal cancer and 1 lip cancer. The cardiac operations followed the operations of malignant tumor in 4 cases and the cardiac operations were followed by the operations of malignant tumor in 7 cases. The former cases did not recur the tumor from 10 to 30 months follow up period. The all latter cases survived except 1 case from 1 month to 21 months. Our management for the cases associated with malignant tumor and cardiac diseases as next. We perform the cardiac operation for the case whose life expectancy is longer than 1 year. We perform the cardiac operation before the operation of malignant tumor. We perform the operation for malignant tumor as soon as the patient had recovered from the cardiac operation. We would not perform any adjuvant therapy before completion of the operation for the heart and tumor.

Aged↗
PubMed1994

Nitric oxide synthase-immunoreactive nerve fibers in the nasal mucosa of the rat.

An immunohistochemical study was performed to detect the localization of nitric oxide synthase (NOS) in the rat nasal mucosa by light and electron microscopy. NOS-immunoreactive nerve fibers were observed around blood vessels and seromucous glands. They were found in the subepithelial layer and even within the epithelium. But no NOS-immunoreactivity was found in the olfactory neuroepithelium. Electron microscopy showed that NOS-immunoreactive nerve profiles were in close contact with the cytolemma of respiratory epithelial cells and acinar cells of seromucous glands. NOS-immunoreactive axon varicosities were located at a considerable distance from the smooth muscle of arterioles and small veins as well as the endothelial cells of venules and capillaries. We confirmed that NOS-containing nerves innervated the epithelium, blood vessels and seromucous glands of the nasal mucosa. These findings, collectively, suggested the possibility that nitric oxide participated in the sensory function of the epithelium, the secretory activities of the nasal gland, and the regulation of vascular tone and vascular permeability in the nasal mucosa.

Amino Acid Oxidoreductases↗
PubMed1994

Nitric oxide involvement in tumor-induced immunosuppression.

The mechanisms of immunosuppression induced by colon cancer in rats were investigated at the systemic and tumor levels. During tumor growth (after i.p. injection of rat colon adenocarcinoma cells in syngeneic BD IX rats), Con A-induced proliferation of splenic mononuclear cells decreased and nitric oxide (NO) production by splenic macrophages increased concomitantly. Incubating splenic mononuclear cells with an inhibitor of NO synthase, NG-monomethyl-L-arginine, restored lymphocyte proliferation. A low level of inducible NO synthase mRNA was detectable in tumors by Northern blotting, with a weak increase during tumor growth. The NO concentration measured in the tumor nodules increased weakly parallel to the tumor growth. Five and six weeks after tumor cell injection, tumor-infiltrating lymphocytes from disaggregated tumors did not proliferate in the presence of Con A. Addition of NG-monomethyl-L-arginine inhibited the production of NO in tumor dissociations and enhanced tumor-infiltrating lymphocyte proliferation. Glyceryl trinitrate (a NO-releasing compound) totally inhibited the lymphocyte proliferation in vitro while it slightly reduced the tumor cell proliferation. T lymphocytes were therefore more sensitive to NO than were tumor cells. Culture medium from tumor cells induced NO production by splenic macrophages, although the factor involved has not yet been identified. Furthermore, tumor cells could also play a part in NO production by tumors because the tumor cells were induced to produce NO by IFN-gamma plus IL-1. These results strongly suggest the participation of NO in the tumor-induced immunosuppression in rats.

Amino Acid Oxidoreductases↗
PubMed1994

Frequency dependence of electric-field-induced orientation of myelin tubes.

Orientation induced by an alternating electric field was studied for myelin tubes of egg phosphatidylcholine (egg-PC) in water and in KCl electrolyte solution. The orientation was also studied for myelin tubes of egg-PC/cholesterol mixtures in water. The orientation effect was measured by the bending curvature of myelin tubes with hairpin-like deformation at frequencies between 10 kHz and 20 MHz. The bending deformation of egg-PC myelin tubes in water decreased abruptly with a decreasing frequency within the low-frequency range below 100 kHz, and shrinkage of myelin tubes was often observed. The bending deformation decreased as the frequency was increased in a higher frequency range. The profile of the frequency dependence for egg-PC in KCl solution was similar to that in water but shifted towards a higher frequency. At low KCl concentrations below 3 mM, the relaxation frequency increased proportionally with increasing an KCl concentration, which was due to a proportional increase in the conductivity of the surrounding medium. Similar profiles of the frequency dependence were observed for egg-PC/cholesterol mixtures but with no shift in the relaxation frequency. These data in the high-frequency range fitted well with calculations based on theoretical equations for the electric-field-induced orientation of nonspherical particles. The conductivity of myelin tubes was estimated to be in the order of 10(-4) S/m in water and of 10(-3) S/m at the low KCl concentrations. The bending modulus of a bilayer membrane was estimated to be (1.0 +/- 0.5) x 10(-19) J for egg-PC in water. No change in the bending modulus was observed for egg-PC in KCl solution. However, for egg-PC/cholesterol mixtures in water, the bending modulus abruptly increased to (1.8 +/- 0.5) x 10(-19) J at a cholesterol concentration of 40 mol%.

Egg Yolk↗
PubMed1994

Chronic infections and inflammatory processes as cancer risk factors: possible role of nitric oxide in carcinogenesis.

Infection by bacteria, parasites or viruses and tissue inflammation such as gastritis, hepatitis and colitis are recognized risk factors for human cancers at various sites. Nitric oxide (NO) and other oxygen radicals produced in infected and inflamed tissues could contribute to the process of carcinogenesis by different mechanisms, which are discussed on the basis of authors' studies on liver fluke infection and cholangiocarcinoma development. A similar mechanism could apply to other suspected and known cancer-causing agents including Helicobacter pylori infection (stomach cancer) or asbestos exposure (lung mesothelioma). Studies on the type of tissue and DNA damage produced by NO and by other reactive oxygen species are shedding new light on the molecular mechanisms by which chronic inflammatory processes may initiate or enhance carcinogenesis in humans.

Bacterial Infections↗
PubMed1994

Effects of axial traction stress on solute transport and proteoglycan synthesis in the porcine intervertebral disc in vitro.

The effects of axial traction stress on intradiscal hydration, solute transport and proteoglycan synthesis were examined in 658 porcine coccygeal intervertebral discs in vitro. Measurements were performed in three tissue fractions: nucleus pulposus, inner and outer annulus fibrosus. At 0.80 MPa traction stress, the equilibrium hydration did not change in the nucleus pulposus. However, in the inner and outer annulus, the equilibrium hydration was reduced, and the change led to an increase of the effective fixed charge density. Diffusion of solute to the nucleus pulposus was significantly suppressed at 0.80 MPa traction stress. The fluid flow of the intervertebral disc tended to be suppressed during the creep recovery process after compression. The proteoglycan synthesis rate in the outer annulus was markedly suppressed by traction stress of 0.80 MPa for 4 h, but not that in the nucleus pulposus. These results suggest that a prolonged excessive axial traction stress induces a decrease in tissue hydration in the annulus fibrosus, and this may lead to an increase in the fractional volume of solid in the matrix and tissue osmotic pressure, resulting in diffusion inhibition of solute and suppression of proteoglycan synthesis. Thus, prolonged and excessive spinal traction may accelerate disc degeneration.

Animals↗
PubMed1994

Analysis of electrophoretic mobility data for human erythrocytes according to sublayer models.

An attempt was made to analyze the electrophoretic mobility data of human erythrocytes in media of different pH values and ionic strengths through cell surface models in which the surface charge layer consists of several ion-penetrable sublayers with a uniform charge distribution in each sublayer. As a result, the three-sublayer model was found to explain the mobility data much better than the two-sublayer model in a wide range of ionic strength at all pH values studied.

Erythrocytes↗
PubMed1994

Intravesical mitomycin C and doxorubicin sequential therapy for carcinoma in situ of the bladder: a longer followup result.

A total of 43 patients with carcinoma in situ of the bladder (primary in 26 and secondary in 17) who underwent intravesical mitomycin C and doxorubicin sequential therapy for 2 multicenter studies were followed for a median period of 45 months (range 10 to 84). Of the patients 32 (74%) achieved complete response after induction therapy and underwent maintenance therapy with either mitomycin C plus doxorubicin, mitomycin C alone or observation only. Of the complete responders 13 (41%) had a local recurrence, and subsequent repeat intravesical mitomycin C and doxorubicin sequential therapy as well as bacillus Calmette-Guerin was effective in a significant proportion (75% or greater). The maintenance therapy did not have a favorable effect on the recurrence rate. In 8 patients (19%) (3 of 32 complete responders and 5 of 11 nonresponders) progression developed, including invasive cancers in 4, metastatic disease in 2 and both conditions in 2. Initial complete responders had a significantly higher progression-free rate than initial nonresponders, although there was no difference in the sites of progression between them. At the last followup 35 patients (81%) remained free of disease with 31 (72%) having a normally functioning bladder. According to these results, intravesical mitomycin C and doxorubicin sequential therapy appears to be applicable as initial treatment for carcinoma in situ of the bladder.

Administration, Intravesical↗
PubMed1994

Increased nitrosamine and nitrate biosynthesis mediated by nitric oxide synthase induced in hamsters infected with liver fluke (Opisthorchis viverrini).

We previously reported that increased endogenous nitrosation in human subjects infected with the liver fluke Opisthorchis viverrini in north-east Thailand could be a risk factor for the development of cholangiocarcinoma. In the present study we examined our hypothesis that this increased endogenous nitrosation is mediated by nitric oxide (NO) synthase induced by O. viverrini infestation. Syrian golden hamsters experimentally infected with O. viverrini liver fluke excreted in the urine significantly greater amounts of nitrate, a stable oxidization product of NO, than untreated hamsters (3.64 +/- 0.86 versus 2.64 +/- 0.60 mumol/hamster/day, P < 0.001). When the rapidly nitrosatable thiazolidine 4-carboxylic acid was administered orally, the infected hamsters also excreted significantly elevated levels of N-nitrosothiazolidine 4-carboxylic acid than untreated hamsters (4.27 +/- 2.20 versus 2.33 +/- 1.13 nmol/hamster/day, P < 0.01), indicating that endogenous nitrosation is elevated in the animals with liver fluke. NO synthase activity measured in liver cytosol was about twice as high in the infected hamsters as in untreated animals. The enzyme, whose biochemical characteristics were similar to that induced in activated murine macrophages, was immunohistochemically localized in the cytoplasm of macrophages and eosinophils in the inflammation zone surrounding the parasite-containing bile ducts. These results support our hypothesis that, in fluke-infected subjects, NO synthase induction leads to excess production of NO and the observed elevated endogenous nitrosation. Since high concentrations of NO exert cytotoxic and mutagenic effects per se, excess NO produced in chronically infected/inflamed tissues may also play a role in initiation and subsequent modulation stages of cholangiocarcinoma development.

Amino Acid Oxidoreductases↗
PubMed1994

The relationship between odontoblasts and immunocompetent cells during dentinogenesis in rat incisors: an immunohistochemical study using OX6-monoclonal antibody.

The relationship between odontoblasts and class II major histocompatibility complex (MHC) antigen-expressing cells in the process of dentinogenesis was studied in rat lower incisors, employing immunohistochemistry using OX6-monoclonal antibody. The dental pulp contained numerous OX6-immunopositive cells that varied in morphology from dendritic to spindle under physiological conditions. Under the electron microscope, these immunopositive cells shared common cytoplasmic features, i.e., multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. At the early stage of dentinogenesis, OX6-immunopositive cells, presumably of the immature type, were located in the subodontoblastic layer. During active dentin formation, the OX6-immunopositive cells increased in number and appeared in the odontoblast layer, associating intimately with fenestrated capillaries situated close to the predentin. These cells showed a dendritic appearance and possessed various sizes of multivesicular bodies and characteristic fine tubulovesicular structures, but never contained typical phagosomes. On the other hand, immunopositive macrophages characterized by typical phagosomes tended to occupy the central portion of the pulp. The results suggest that most, if not all, OX6-immunopositive cells situated deep in the odontoblast layer are dendritic cells playing a role in the defense system of the dental pulp against antigenic molecules arriving from the circulation via the fenestrated capillaries. The increasing number of OX6-immunopositive or immunonegative macrophages appearing near the incisal end of the tooth is thought to be involved in the elimination of degenerated odontoblasts.

Animals↗
PubMed1994

[Clinical evaluation of a new carbapenem antibiotic, biapenem (L-627), in the pediatric field].

Biapenem (L-627) was evaluated for its safety and efficacy in 27 children with various bacterial infections. L-627 was effective in cases with osteomyelitis due to Staphylococcus aureus, pneumonia and purulent meningitis due to penicillin-resistant Streptococcus pneumoniae, and urinary tract infections due to Enterococcus faecalis, Escherichia coli, or Pseudomonas aeruginosa. However, L-627 failed to produce good responses in 2 of 7 cases of Haemophilus influenzae infections. Pharmacokinetic parameters of 30-minutes infusion of 12 mg/kg were as follows: Cmax 29-46 micrograms/ml, T 1/2 0.68-0.94 hr. Adverse reactions were minimal. These data suggest that L-627 is safe in children, and is valuable especially for treatment of infections in immunocompromised hosts and infections due to multiply resistant bacteria.

Adolescent↗
PubMed1994

Anterior interbody fusion with and without interspinous block implementation for lumbar isthmic spondylolisthesis.

The clinical and radiographic results of lumbar isthmic spondylolisthesis were compared between interspinous block-assisted anterior interbody fusion (block-assist group, n = 16) and anterior interbody fusion with no use of the block (nonassist group, n = 17) with an average follow-up of 7 years (range 1 1/3-13 years). Satisfactory relief of low-back pain, significantly early interbody union (union rate 88%, p < 0.05), and spontaneous fusion of pars defect (fusion rate 44%, p < 0.05) were obtained in the block-assist group. In the nonassist group, interbody union was markedly delayed (p < 0.05), the union rate was 53%, and spontaneous fusion of the pars was found in 12% of patients. The overall clinical results at final follow-up in both groups did not show a statistically significant difference, but the results tended to be superior in the block-assist group.

Adolescent↗
PubMed1993

Spin-trapping detection of precursors of hydroxyl-radical-induced DNA damage: identification of precursor radicals of DNA strand breaks in oligo(dC)10 and oligo(dT)10.

A spin-trapping method combined with enzymatic digestion and high-performance liquid chromatography was employed to detect hydroxyl-radical-induced precursors of strand breaks in oligonucleotides ((dC)10 and (dT)10) as DNA models. Radicals produced as precursors of both strand breaks and base alterations were first trapped by the spin trap 2-methyl-2-nitrosopropane. The oligonucleotides containing spin adducts were subsequently digested by snake venom phosphodiesterase to release low-molecular-weight nitroxide fragments. In this way, several spin adducts were separated by high-performance liquid chromatography. In both oligonucleotides, ESR spectra attributable to the spin adducts derived from trapping of a precursor radical of strand breaks (the C4'-sugar radical) were observed. To further confirm this assignment, the induction of strand breaks was examined by polyacrylamide gel electrophoresis of 5'-32P-end-labeled oligonucleotides. Autoradiograms of the gels showed that the fragments corresponding to monomers to 9mers were formed in both oligonucleotides. When experiments were carried out under conditions in which hydroxyl radicals reacted with oligomers in the presence of the spin trap, the spin trap was found to suppress the fragmentation more than it did by scavenging hydroxyl radicals, indicating that the precursor radical of strand breaks (the C4' radical) was trapped. The present experiments showed that the spin-trapping method combined with gel electrophoresis was a good approach to identify sites of radical damage which cause strand breaks in oligonucleotides (probably in DNA).

DNA Damage↗
PubMed1993

Molecular cloning of a cDNA encoding an inducible calmodulin-dependent nitric-oxide synthase from rat liver and its expression in COS 1 cells.

Calmodulin-dependent nitric-oxide synthase, with an apparent molecular mass of 125 kDa, was induced in the liver of rats treated with Propionibacterium acnes and Escherichia coli lipopolysaccharide. Clones were isolated from a cDNA library obtained from induced rat liver using oligonucleotide probes which were synthesized based on the amino acid sequences of peptides of the purified enzyme. Four overlapping cDNA clones for a 3.8-kbp region were isolated and the nucleotide sequences were determined. These clones encompassed an open-reading frame of 3441 bases encoding 1147 amino acids. The deduced amino acid sequence of the cDNA suggested that the protein contains binding sites for NADPH, FAD and FMN. The structure of the possible calmodulin-binding site, consisting of a strongly hydrophobic region surrounded by basic amino acids, is present. The full-length cDNA was expressed in COS 1 cells under the control of a cytomegalovirus promoter and the expressed enzyme was found to be a calmodulin-dependent nitric-oxide synthase. A structural comparison suggested that the liver nitric-oxide synthase is the same as the macrophage enzyme. Northern-blot analysis showed that the mRNA in the liver is approximately 4.2 kb long and is induced transcriptionally by treatment with P. acnes and lipopolysaccharide.

Amino Acid Oxidoreductases↗
PubMed1993

Direct synaptic contacts of nitric oxide synthase-immunoreactive nerve terminals on the neurons of the intracardiac ganglia of the guinea pig.

Immunoelectron microscopy was performed to localize immunoreactivity for nitric oxide synthase (NOS) in guinea pig atria. Many round intracardiac ganglia, close to the openings of the pulmonary veins, contained NOS-immunoreactive neurons. A small number of neurons were immunoreactive, but most of the non-immunoreactive neurons were surrounded by immunoreactive axons. Direct axo-somatic or -spinic synapses from NOS-immunoreactive axon varicosities to intracardiac ganglionic neurons were observed. The present results raise the possibility that nitric oxide plays a role in the neural control of the heart through synapses in the cardiac ganglia.

Amino Acid Oxidoreductases↗
PubMed1993

Geographic association between urinary excretion of N-nitroso compounds and oesophageal cancer mortality in China.

Overnight urine samples were collected from approximately 60 male adults in each of 69 counties of China in 1989. Two specimens were collected from each subject--one after a loading dose of proline and ascorbic acid and another after a loading dose of proline only. Levels of N-nitrosamino acids and nitrate were measured in urine samples and correlated with cumulative mortality rates for subjects aged between 0 and 64 years in the 1970s. Oesophageal cancer mortality rates were positively and significantly associated with (i) urinary levels of excreted N-nitrosoproline (NPRO) (after proline and ascorbic acid loading or proline loading only), (ii) N-nitrososarcosine levels, and (iii) nitrosation potential (the decrease in the amount of urinary NPRO after adding ascorbic acid to the proline load). There were also positive correlations between the urinary level of NPRO or other N-nitrosamino acids and that of nitrate. The urinary excretion of nitrate was associated with consumption of various nitrate-rich vegetables. The results suggest that N-nitroso compounds (NOC) or other nitrite-derived carcinogens are implicated in the aetiology of oesophageal cancer in China.

Adult↗