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Biomedical subjects

J Masuda

Publications and source records attributed to J Masuda.

At least 19 recordsLinked to original sources
PubMed2006

Activation of c-Jun N-terminal kinase (JNK) signalling in experimentally induced gastric lesions in rats.

The c-Jun N-terminal kinase (JNK) participates in intracellular signalling cascades that mediate inflammatory responses. Therefore, the JNK signalling may be involved in gastric injury and inhibition of this pathway may form the basis of a new strategy for the treatment of gastric injury. The aim of this study was to determine whether JNK participates in the formation of gastric lesions in an experimental model. Acute gastric injury was induced in Sprague-Dawley rats by intragastric administration of 100% ethanol. The amount of phospho-JNK in the rat stomach was determined using immunohistochemistry and Western analysis. Animals received subcutaneous injections of a specific JNK inhibitor SP600125 or vehicle and the extent of mucosal damage in the stomach was determined. Western analysis revealed early phosphorylation of JNK and, to a lesser extent, p38 as well as late phosphorylation of the p42/44 extracellular signal-related kinases during the development of gastric lesions. JNK was phosphorylated in epithelial cells and in occasional mononuclear cells present at lesion sites. These cells were rarely found in samples from control specimens. Treatment with SP600125 significantly reduced the extent of gastric lesions. These findings indicate that experimental gastric injury is associated with activation of the JNK signalling pathway, and also suggest that JNK inhibitors may play a role in the treatment of gastric injury in humans.

Animals↗
PubMed2006

A form of circulating interleukin-6 receptor component soluble gp130 as a potential interleukin-6 inhibitor in inflammatory bowel disease.

The presence and the role of soluble gp130, the soluble form of a component of the interleukin (IL)-6 receptor complex, were investigated in inflammatory bowel disease. The serum concentrations of soluble gp130 were increased in ulcerative colitis (active disease, median, 93.5 ng/ml; interquartile range, 26-125 ng/ml; inactive disease, 81 ng/ml, 24.8-137.3 ng/ml) and to a lesser extent in Crohn's disease (active disease, 66 ng/ml, 44.4-87.6 ng/ml; inactive disease, 63 ng/ml, 43.5-82.5 ng/ml) compared to normal controls (43 ng/ml, 27-59 ng/ml). Paired analysis of serum samples showed a decrease of IL-6 and soluble IL-6 receptor concentrations in both diseases and an increase of soluble gp130 concentrations, especially in ulcerative colitis, just after the resolution of disease exacerbation. Size fractionation of the serum revealed that a part of the IL-6 co-eluted with soluble gp130 and soluble IL-6 receptor. The IL-6-induced proliferation of murine B9 hybridoma was enhanced by recombinant soluble IL-6 receptor, whereas the proliferation was inhibited by recombinant soluble gp130. These results indicate that soluble gp130 may function as a natural inhibitor of the IL-6 actions in inflammatory bowel disease.

Acute Disease↗
PubMed2005

Feeding with powdered diet after weaning affects sex difference in acetylcholine release in the hippocampus in rats.

We have reported in the past that female rats fed a powdered diet showed better spatial learning and memory functions than female rats a fed pelleted diet. In the present study, we examined the effects of feeding with powdered diet on acetylcholine release in the hippocampus in both sexes of rats. After weaning (3 weeks of age), rats were fed either standard pelleted diet or powdered diet, and after maturation (9-12 weeks of age), they were used in an in vivo microdialysis study, in which no eserine (a cholinesterase inhibitor) was added to the perfusate. The dialysate was collected from the dorsal hippocampus at 20-min intervals under freely moving conditions for more than 24 h. Acetylcholine in the dialysate was measured by high performance liquid chromatography. As we reported previously, the acetylcholine release showed a clear daily rhythm in both sexes, and males showed significantly greater acetylcholine release in the hippocampus than females in rats fed pelleted diet. Conversely, in rats fed powdered diet, no sex difference in the acetylcholine release was observed, since feeding with powdered diet significantly increased the acetylcholine release only in females. To further examine the number of cholinergic neurons in the medial septum and horizontal limb of the diagonal band of Broca, immunocytochemistry for choline acetyltransferase was performed in both sexes of rats fed either standard pelleted diet or powdered diet. However, neither sex nor feeding conditions affect the number of choline acetyltransferase immunoreactive cells in the areas. These results suggest that powdered diet after weaning enhances spontaneous acetylcholine release in the hippocampus in female rats without changes in the number of cholinergic neurons in the areas. It is possible that this effect of feeding contributes to improve the performance in spatial learning and memory functions in female rats fed powdered diet.

Acetylcholine↗
PubMed2005

Sex and housing conditions affect the 24-h acetylcholine release profile in the hippocampus in rats.

To examine the sex difference in the 24-h profile of the acetylcholine (ACh) release in the hippocampus, in addition to the effects of housing conditions on this profile, we performed an in vivo microdialysis study in intact male and cycling female rats that had been living in large (diameter=35 cm) or small (diameter=19 cm) cylindrical cages. Each rat was individually housed in a cage for 4 days. On the day of the experiment, the dialysate was collected from the dorsal hippocampus at 20-min intervals and sequential blood samples were simultaneously obtained at 2-h intervals, under the freely moving condition for more than 24 h. ACh in the dialysates was measured by the high performance liquid chromatography system, while the corticosterone concentration in the serum was measured by radiostereoassay. Although the ACh release showed a clear daily rhythm in both sexes of rats, the amount of ACh released in female rats was significantly lower than that in males. Furthermore, the housing in the small cage significantly attenuated the ACh release during the dark phase in male rats, but not in female rats. Conversely, the serum corticosterone concentration showed a clear daily rhythm and the mean concentration of serum corticosterone in female rats was significantly higher than that in male rats. Housing in the small cage did not affect the corticosterone rhythm in either sex. These results reveal a sex difference in the 24-h profile of the ACh release, which suggests vulnerability of the cholinergic system in male rats depending on its housing conditions.

Acetylcholine↗
PubMed2005

Diminished cytokine signalling against bacterial components in mononuclear leucocytes from ulcerative colitis patients after leukocytapheresis.

Infiltration by circulating inflammatory cells is a prominent local inflammatory feature of ulcerative colitis (UC). Several trials have suggested that leukocytapheresis by filtration can benefit patients with active UC. We investigated how this therapy might modulate the inflammatory response. Patients with active UC who were beginning repeated filtration leukocytapheresis were studied. Mononuclear cell preparations were obtained from blood before and after the first treatment, and expression of cytokine signalling components and the cell-proliferative response were analysed in vitro. Leukocytapheresis reduced lipopolysaccharide-induced production of proinflammatory cytokines (interleukin-1, -6, -8 and tumour necrosis factor-alpha, P < 0.05 for all) and activation of intracellular signalling components (nuclear factor-kappaB, mitogen-activated protein kinases, and signal transducer and activator of transcription-3), as well as surface expression of toll-like receptor-4 (P < 0.05) in mononuclear cells. The therapy also reduced the cell-proliferative response by mononuclear cells stimulated with sonicated bacterial preparations from autologous intestine (P < 0.05). These results indicate that activated mononuclear cells in the peripheral blood of patients with active UC are removed by leukocytapheresis and replaced by cells with a lower activation status. This replacement may partly explain the therapeutic benefit.

Adult↗
PubMed2004

Cryogenic trapping for determination of odor concentration.

The sensory testing method applied under Japanese law to measure odor concentration has a lower detection limit of 10 in the specified Odor Index. To measure odor below the limit, a condensing procedure using solid sorbents (Tenax-TA, Unicarbon B and Carbosieve SIII) has been developed and used in Japan. This procedure however cannot condense all odorous substances, and is specifically unsuited to hydrogen sulfide, methyl mercaptan, dimethyl sulfide, ammonia, and other typical odorous substances. In the present study, cryogenic trapping was tested to improve recovery rate. As water in sample air causes choking of the trap tube, vacant pre-columns to condense the water were connected to the Tenax-TA-packed column. The columns were chilled with liquid oxygen before passage of 100 L of sample air. The columns were then heated to 200 degrees C under passage of 50 mL/min of nitrogen carrier gas to desorb odors. The desorbed gases were captured in sampling bags made of polyethylene terephthalate film. The total volume of desorbed gases was approximately 1 L. The method showed good recovery rates for hydrogen sulfide, methyl mercaptan, dimethyl sulfide and ammonia, and was useful for determining low-level odor concentrations during measurement of odor in ambient air at various sites in Osaka City.

Absorption↗
PubMed2004

Interlaboratory comparison of olfactometry in Japan.

In 2000, 2001, and 2002, interlaboratory comparison of olfactometry was carried out in order to collect basic data for the establishment of a quality control procedure and the determination of quality criteria for the triangular odour bag method. In 2000, interlaboratory comparison was conducted by using a measurement method for samples taken at smoke stacks. On the other hand, the measurement method for samples taken at boundary lines was used for interlaboratory comparison in 2001. A total of seven olfactometry laboratories in Japan participated in each test, and mean values, repeatability standard deviations, reproducibility standard deviations, and standard deviations under intermediate conditions of detection threshold of ethyl acetate were calculated from the results. These values can be used in a quality control process of olfactometry. In 2002, interlaboratory comparison was carried out by using a measurement method for samples taken at smoke stacks. A total of 137 olfactometry laboratories in Japan participated in the test, and 69% of them lay within the permissible range of the odour index.

Air Pollutants↗
PubMed2001

Radical production simulated by photoirradiation of the diol dehydratase-adeninylpentylcobalamin complex.

In the course of structural studies of diol dehydratase-cobalamin complexes, it was found that the electron density corresponding to the cyano group of the enzyme-bound cyanocobalamin is almost not observable at room temperature and very low even at cryogenic temperatures, suggesting its dissociation from the Co atom upon X-ray irradiation. On the contrary, the adenine moiety of the enzyme-bound adeninylpentylcobalamin was clearly located in the electron density map. When the enzyme-adeninylpentylcobalamin complex was illuminated with visible light, the electron density between the C5' and Co atoms disappeared, and the temperature factors of the atoms comprising the pentamethylene group became much larger than those in the dark. This indicates a Co-C bond cleavage and that the adenine moiety remains held by hydrogen bonds with some residues in the enzyme. Thus, the formation of an adenine-anchored radical upon illumination was demonstrated crystallographically with this complex. These observations clearly indicate that homolysis of the Co-C bond of alkylcobalamin takes place upon illumination with visible light but is not readily cleaved during X-ray irradiation.

Crystallography, X-Ray↗
PubMed2001

Second nation-wide study of atherosclerosis in infants, children and young adults in Japan.

This paper reports the results of the second nation-wide cooperative study of atherosclerosis in young Japanese, aged from 1 month to 39 years, who were autopsied between 1991 and 1995. Atherosclerotic lesions in 1066 aortas and 974 coronary arteries were classified into fatty streaks, fibrous plaques and complicated lesions and quantificated with the point-counting method. The results of this study were compared with those of the former study, which was conducted 13 years earlier in almost the same fashion as this study. Atherosclerosis of aorta, which was determined by surface involvement (SI) of atherosclerotic lesions and atherosclerotic index (AI), increased with age in both sexes of the former and the present studies and their tendency for the progression of the extent of atherosclerotic lesions appeared to be similar. In the coronary arteries, the mean values of SI and AI in the males of the present study were greater significantly than those in the male of the former studies and in the female of the both studies in the third and fourth decades. This difference suggests that atherosclerotic lesions are increasing in young Japanese males. It also suggests that these subjects may be increasingly susceptible to atherosclerotic cardiovascular disease with increasing age.

Adolescent↗
PubMed2001

Primary biliary cirrhosis among atomic bomb survivors in Nagasaki, Japan.

Despite rapid progress in methods for analyzing radiation effects, much remains to be learned about the mechanisms and processes of radiation-induced immunological dysfunction. Among 17,899 sera obtained from atomic bomb survivors in Nagasaki, Japan, sera from 484 participants who complied with a reexamination for alkaline phosphatase (ALP) were tested for antimitochondrial antibody (AMA) by indirect immunofluorescence, and autoantibodies against 2-oxo-acid dehydrogenase complex (2-OADC) by immunoblotting to investigate the prevalence of primary biliary cirrhosis (PBC). Of these 484 sera, 28 (5.8%) were seropositive for AMA. The 484 participants were divided into three groups according to distance from the hypocenter: 72 who were exposed within 1999 m (closest group), 368 from 2000 to 5999 m (intermediate distant group), and 44 outside 6000 m (distant group). The positivity rates for AMA in these three groups were 6/72 (8.3%), 22/368 (6.0%), and 0/44 (0%), respectively (P =.08). Furthermore, high titers ( > 1:320) of AMA were observed in 3/6 (50%) AMA-positive sera from the closest group, in contrast to 4/22 (18%) from the intermediate distant group, although there was no significant correlation between AMA titer and distance from the hypocenter (P =.07). Of these 28 AMA-positive sera, 11 (39%) were from participants who had already been diagnosed with PBC, and 25 (89%) contained antibodies against at least one component of 2-OADC enzymes by immunoblotting. Therefore, the prevalence of PBC was estimated to be at least 615 cases per million (792 per million women). Our results suggest that the prevalence of PBC in atomic bomb survivors in Nagasaki is higher than that reported for the general population in Japan, and a further survey of the environmental factors, including radiation exposure, that predispose to PBC would be needed for understanding this disease of unknown etiology.

Aged↗
PubMed2001

Changes in titers of antimitochondrial and antinuclear antibodies during the course of primary biliary cirrhosis.

A case of primary biliary cirrhosis (PBC) in whom a complete biochemical (serum bilirubin, transaminases and alkaline phosphatase) remission was noted after combination treatment with ursodeoxycholic acid (UDCA) and corticosteroid is reported. The antimitochondrial antibody (AMA) detected by indirect immunofluorescence was initially positive, and the antinuclear antibody (ANA) was negative, but these two antibodies subsequently fluctuated independently (AMA-positive/ANA-negative, AMA-negative/ANA-negative, AMA-negative/ANA-positive, AMA-positive/ANA-positive, and again AMA-negative/ANA-positive) in spite of a lack of histopathological improvement in the liver after treatment. The clinical presentation in our case suggests that in some cases the diagnosis of PBC or so-called autoimmune cholangitis (AIC) might depend on the 'phase' of the same disease. Our results also suggest that detailed immunoreactive profiles against 2-oxo-acid dehydrogenase complex (2-OADC) enzymes by using immunoblotting, together with a serial histological examination, should provide more precise information for a diagnosis of PBC.

Adult↗
PubMed2001

Ozone injection into an activated carbon bed to remove hydrogen sulfide in the presence of concurrent substances.

Adsorption using activated carbon is one of the most reliable techniques for preventing odor by substances such as H2S. Concurrent substances in effluent gas often reduce the removal capacity of activated carbon for H2S. As a means of restoring capacity under such conditions, ozone injection into an activated carbon column was examined. When activated carbon was saturated with substances such as toluene, ethanol, n-butanol, or iso-butanol, its capacity to remove H2S decreased in proportion to the amount of the saturating substance. Under such conditions, ozone injection greatly increased capacity. Toluene, which is not easily decomposed by ozone, was displaced by ozone and by oxidized products of H2S. Ethanol, which is adsorbed in small amounts by activated carbon and easily decomposed by ozone, was removed by ozone injection. Butanols, which are also decomposed by ozone and adsorbed in large quantities by activated carbon, showed intermediate behavior between that of toluene and ethanol.

Adsorption↗
PubMed2001

Silent stroke: pathogenesis, genetic factors and clinical implications as a risk factor.

Silent stroke is frequently recognized in elderly persons. Diffusion-weighted magnetic resonance imaging has proved to be highly sensitive in the detection of recent silent stroke, and may further applications in the future. Silent stroke in healthy and asymptomatic individuals mainly comprises lacunar infarcts, which are often associated with white matter changes. Thus, analyses of risk factors and genetic factors in small-vessel diseases such as lacunar infarct and white matter changes may provide clues regarding the pathogenesis of silent stroke. Silent stroke may be a risk factor for clinical stroke and cognitive impairment, but prospective studies are required to confirm this.

Genetic Predisposition to Disease↗
PubMed2001

Lysophosphatidylcholine inhibits T cell-specific CXC chemokines IP-10, MIG, and I-TAC expression induced by IFN-gamma in human endothelial cells.

Hypercholesterolemia is reported to be associated with a T helper (Th) 1 to Th2 switch in apoE-deficient mice. To explore the underlying mechanisms of such immune modulation, we investigated if lysophosphatidylcholine (Lyso-PC), enriched in oxidized LDL, affects cytokine-induced expression of Th1 cell-specific CXC chemokines, IFN-inducible protein of 10 kDa (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T cell a chemoattractant (1-TAC) in cultured endothelial cells. Lyso-PC inhibited IFN-gamma or IFN-gamma plus TNF-alpha-induced IP-10, Mig, and I-TAC mRNA expression but not that of the IRF-1 or IRF-1 dependent molecule, GBP. It also inhibited IP-10 protein secretion in conditioned media induced by IFN-gamma or IFN-y plus TNF-alpha Western analysis demonstrated that Lyso-PC inhibited IFN-gamma-induced STAT-1alpha protein expression, but not that of IRF-1. These results suggest that Lyso-PC selectively inhibits IP-10, Mig, and I-TAC expression through IRF-1-independent mechanisms. This inhibitory effect of Lyso-PC may be involved in the immune modulation by hypercholesterolemia.

Chemokine CXCL10↗
PubMed2001

Improved reproducibility of intravascular ultrasound assessment of coronary in-stent neointima with the use of an echogenic contrast agent.

The present study evaluated a new technique that has the potential to improve the border detection of in-stent neointima using an echogenic contrast agent during intravascular ultrasound (IVUS). To confirm the reproducibility of IVUS imaging for measuring the cross-sectional in-stent neointima area, inter- and intra-observer variability and correlation were determined. Conventional IVUS (plain IVUS) and IVUS using a contrast agent (contrast IVUS) were performed in 24 subjects 6.5+/-1.5 months after undergoing a Palmaz-Schatz coronary stent implant. Conventional IVUS delineated completely the in-stent neointima in 6 subjects (25%). In the remaining 18 subjects (75%), delineation of the neointima was incomplete despite the use of various combinations of imaging conditions (eg, transmission, compress, post-process). With contrast IVUS, the boundary of the neointima, and therefore the neointima area, was clearly distinguishable, and this resulted in complete delineation of the neointima in all 24 subjects. With a contrast agent, inter- and intra-observer variability significantly decreased (0.94+/-0.69mm2 conventional IVUS vs 0.37+/-0.40mm2 contrast IVUS, p<0.001; 0.69+/-0.56mm2 conventional IVUS vs 0.07+/-0.10mm2 contrast IVUS, p<0.0001; respectively). Thus, contrast IVUS provides a reproducible method for the quantitative analysis of in-stent neointima with excellent inter- and intra-observer correlation.

Aged↗
PubMed2000

How a protein generates a catalytic radical from coenzyme B(12): X-ray structure of a diol-dehydratase-adeninylpentylcobalamin complex.

BACKGROUND: Adenosylcobalamin (coenzyme B(12)) serves as a cofactor for enzymatic radical reactions. The adenosyl radical, a catalytic radical in these reactions, is formed by homolysis of the cobalt-carbon bond of the coenzyme, although the mechanism of cleavage of its organometallic bond remains unsolved. RESULTS: We determined the three-dimensional structures of diol dehydratase complexed with adeninylpentylcobalamin and with cyanocobalamin at 1.7 A and 1.9 A resolution, respectively, at cryogenic temperatures. In the adeninylpentylcobalamin complex, the adenine ring is bound parallel to the corrin ring as in the free form and methylmalonyl-CoA-mutase-bound coenzyme, but with the other side facing pyrrole ring C. All of its nitrogen atoms except for N(9) are hydrogen-bonded to mainchain amide oxygen and amide nitrogen atoms, a sidechain hydroxyl group, and a water molecule. As compared with the cyanocobalamin complex, the sidechain of Seralpha224 rotates by 120 degrees to hydrogen bond with N(3) of the adenine ring. CONCLUSIONS: The structure of the adenine-ring-binding site provides a molecular basis for the strict specificity of diol dehydratase for the coenzyme adenosyl group. The superimposition of the structure of the free coenzyme on that of enzyme-bound adeninylpentylcobalamin demonstrated that the tight enzyme-coenzyme interactions at both the cobalamin moiety and adenine ring of the adenosyl group would inevitably lead to cleavage of the cobalt-carbon bond. Rotation of the ribose moiety around the glycosidic linkage makes the 5'-carbon radical accessible to the hydrogen atom of the substrate to be abstracted.

Bacterial Proteins↗
PubMed2000

Serial changes in enzyme inhibitory antibody to pyruvate dehydrogenase complex during the course of primary biliary cirrhosis.

To assess the usefulness of enzyme inhibition assay for the diagnosis of primary biliary cirrhosis (PBC), we determined the serial changes in enzymatic inhibitory antibody to pyruvate dehydrogenase complex (PDC) in patients with PBC, and compared the results to those of immunofluorescence and immunoblotting. Forty-nine sera from 19 patients with PBC who were followed-up for at least 16 months were tested for antimitochondrial antibodies (AMA) by indirect immunofluorescence, immunoblotting on bovine heart mitochondria, and enzyme inhibition assay using commercially available TRACE Enzymatic Mitochondrial Antibody (M2) Assay (EMA) kit. Of the 49 sera, 39 (80%), 35 (71%), 38 (78%), 31 (63%), and 36 (73%) were positive for AMA by immunofluorescence, for immunoglobulin G (IgG), IgM, and IgA class antibody against E2 subunit of PDC (PDC-E2) by immunoblotting, and for enzymatic inhibitory antibody to PDC by EMA, respectively. AMA titers determined by immunofluorescence did not change in 9 patients (47%), increased in 4 (21%), decreased in 3 (16%), and fluctuated in 3 (16%) during follow-up. The number of anti-M2 bands by immunoblotting did not change in 9 (47%), increased in 6 (32%), decreased in 2 (11%), and fluctuated in 2 (11%). Units of PDC activity by EMA did not change markedly in 16 (84%), increased in 2 (11%), and fluctuated in 1 (5%). Positive EMA results were common in cases with high levels of serum alkaline phosphatase and IgM, and the units of PDC activity by EMA correlated significantly and inversely with AMA titers by immunofluorescence, and serum reactivity to PDC-E2 by immunoblotting, respectively. There was no correlation between serial changes in biochemical data and units of PDC activity by EMA. In three patients who showed a decrease in AMA titers, AMA titers correlated more with EMA results than immunoblotting. Moreover, in a patient with fluctuating AMA titers, the units of PDC activity by EMA paralleled AMA titers. Our results suggest that EMA is useful for the diagnosis of AMA-positive PBC, and also could be used for monitoring the disease course in PBC.

Adult↗