Search PubMed⌕ Search

Biomedical subjects

T Komoda

Publications and source records attributed to T Komoda.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Nose bleeds and nitric oxide in the nose].

Most of the nitric oxide (NO) in expiratory air is produced by the nose and its accessory sinuses, and nasal allergies related to NO have been often reported. In the present study, we postulated that nose bleeds may be somehow related to reactive oxygen species. The expression of NO synthase (NOS) by the nasal mucosa was evaluated using the RT-PCR method, and the concentration of NO in air expired through the nose was measured. The activity of superoxide dismutase, which scavenges superoxide anions, was also evaluated. The genetic expression of iNOS was observed in the nasal mucosa, and a significantly lower level of expression was noted in subjects with a nosebleed, compared to that of the controls. This result was interpreted as indicating a decrease in NO levels as a result of the nosebleed, leading to an elevation in blood pressure. Transient elevations in blood pressure caused by oxidative stress may lead to the rupture of nasal vessels if hypertension preexists. Serum levels of superoxide dismutase increased significantly in subjects with nose bleeds. This finding might be related to the activity of the superoxide anion, which is released in large amounts during nose bleeds. Serum superoxide dismutase levels increase in response to the high concentration of superoxide anions. The concentration of NO in air expired through the nose was significantly lower in subjects with nose bleeds, compared to that of the control subjects. We suggest that NO production decreases in subjects experiencing nose bleeds and that this reduction is induced by preexisting hypertension and injury from reactive oxygen species, contributing to the resulting nose bleed.

Adult↗
PubMed2000

[Expression of reactive oxygen-species related enzymes in endothelial cells stimulated with glycated lipoproteins].

Glycated lipoproteins, which elevate the blood in diabetic patients, cause direct attenuation of endothelial function. Increased glycation of apolipoproteins may play a trigger role in the accelerated development of atherosclerosis in the patient with diabetes. Here we assessed whether glycated lipoproteins affect on the endothelial function with particular emphasis on the role of reactive oxygen species in vitro. Incubation of human aortic endothelial cells(HAEC) with glycated LDL had little influence on the expression of antioxidant enzymes such as nitric oxide synthase(NOS), Cu2+Zn(2+)-superoxide dismutase (Cu2+Zn(2+)-SOD), catalase, and p22 phox in the cells. In contrast, exposure of glycated HDL induced a marked decrease of Cu2+Zn(2+)-SOD, catalase, and endothelial NOS as well as a slight increase of p22 phox in HAEC in term of both protein and mRNA expression, suggesting that increased formation of reactive oxygen species such as O2- and OH radical participate in the deterioration for the function of vascular endothelial cells in diabetic patients.

Arteriosclerosis↗
PubMed2000

Annular stabilization in mitral repair without a prosthetic ring.

BACKGROUND AND AIM OF THE STUDY: Annular stability is not guaranteed after mitral repair without a prosthetic ring. We introduce a newly developed plication technique and detail its stabilizing effect on the mitral annulus after Gerbode plasty. METHODS: Patients suffered degenerative mitral valve prolapse with chordal rupture restricted to the middle scallop of the posterior leaflet. Between 1986 and 1997, 102 patients underwent Gerbode plasty with or without annular reinforcement with a pericardial strip or modified Paneth plasty (group C). The mean (+/- SD) follow up was 70.4 +/- 41.1 months. Since 1996, 32 patients have undergone a newly developed annuloplasty technique (group N), where a pericardial strip was tightly anchored to the bilateral trigones and posterior annulus, which was folded by Gerbode plasty. With the final anchoring suture the intention was to prevent plication breakdown of this portion. Mean follow up for this group was 17.6 +/- 7.1 months. Progression of mitral regurgitation after surgery in both groups was studied. RESULTS: In group C, postoperative progression of mitral valve regurgitation occurred in 41.1% of patients (5.9% to grade 1, 17.6% to grade 2, 17.6% to grade 3). Among these patients, reoperation was due to plication breakdown of the Gerbode plasty in six cases (5.9%), and to either chordal rupture or annular dilatation in 10 cases each (9.8%). In contrast, no reoperation due to recurrent severe mitral regurgitation was needed in group N. Progression of mitral regurgitation after surgery was seen in six patients (two to grade 1; four to grade 2). CONCLUSION: The newly developed annuloplasty technique may be useful in stabilizing the mitral annulus after Gerbode plasty.

Adolescent↗
PubMed1999

Reactive oxygen species as a risk factor in verotoxin-1-exposed rats.

It has been suggested the the interaction of Escherichia coli O157-derived verotoxins (VTs) with the vascular endothelium plays a central role in the pathogenesis of the thrombotic microangiopathy and ischemic lesions characteristic of hemolytic uremic syndrome (HUS) and E. coli O157-associated hemorrhagic colitis. Intravenous administration of both E. coli O157-derived VT1 and lipopolysaccharide (LPS) in the rat induced a synergistic increase in thiobarbituric acid (TBA) values in those animal's plasma, as compared with that injected with VT1 or LPS alone. We then hypothesized that an increase in lipid peroxidation in the rat plasma was due to an enhanced production of endothelial cell-derived reactive oxidant. Based on determination of rat sera and cultured human aortic endothelial cells (HAECs), VT1 had little if any effect on LPS-stimulated increase of nitric oxide and the resultant peroxynitrite generations. Both RT-PCR and Western blot studies of reactive oxygen species-related enzymes showed that VT1 markedly decreased the expression of catalase mRNA and protein in HAECs, but caused less alteration in the levels of Cu, Zn-superoxide dismutase, and NADPH oxidase mRNA. Further studies by spin trapping analysis using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) revealed a time-dependent increase in hydroxyl radicals by VT1 in HAECs. The accumulated data thus suggest that bacterial VT1 reduces mainly catalase levels in endothelial cells, which is synergistically potentiated by LPS, and that the resulting hydroxyl radical participates in endothelium injury through a marked enhancement of lipid peroxidation, leading to HUS.

Animals↗
PubMed1999

[Detection of anti-Chlamydia trachomatis antibody by means of enzyme immunoassay using synthetic peptide antigen].

Newly developed diagnostic kits for the detection of Anti-Chlamydia trachomatis, Peptide-Chlamvdia (LOY: Meiji Milk Products Co., Ltd., Tokyo; for IgG and IgA), were evaluated using the microimmunofluorescence assay (MIF) as the gold standard. These results were also compared to results of testing by Sero-IPALISA and immunoblot (I-B). Detection by LOY in based on enzyme immunoassay with synthetic peptides as the antigen. Thirty serum samples from pediatric patients and 130 serum samples from gynecology patients were used. All 26 pediatric samples that were positive for Chlamydia pneumoniae IgG antibody tested negative with LOY, indicating that the presence of the antibody against C. pneumoniae did not affect the assay by LOY. For 90 gynecological samples, the total, the positive and the negative agreement rates for IgG were quite high; i.e. 87.8%, 90.0% and 70.0% (LOY vs MIF), 85.6%, 85.0% and 90.0% (Sero-IPALISA vs MIF), and 92.0%, 94.9% and 70.0% (I-B vs MIF), respectively. On the other hand, many cases of MIF (-) and LOY (+) discrepancy were seen in IgA detection. In order to better understand the basis for such disagreement. 34 serum samples were collected from patients whose cervical samples were negative for the Chlamydia group antigen based on the assay with IDEIA-Chlamydia. They were then assayed by MIF and LOY. The total, the positive and the negative agreement rates for IgG were 91.2%, 100% and 90.9%, while the total and the negative agreement rates for IgA were 88.2% and 88.2% (there were no IgA positive cases). Furthermore, 6 serum samples (1 case of MIF (+) LOY (+) and 5 cases of MIF (-) LOY (+)) were provided to determine whether LOY detects C. trachomatis specific IgA antibody. Increasing amounts of C. trachomatis serovar L2 were added to the serum samples resulting in a progressive decrease in their reactivity in the LOY assay. These results lead us to speculate that LOY can reveal even low levels of C. trachomatis specific IgA antibody. In conclusion, LOY can be used as an useful kit for detecting C. trachomatis antibody.

Antibodies, Bacterial↗
PubMed1999

[Small increases of the serum alkaline phosphatase activity and malignant changes].

In order to see the clinico-pathological significance of the small increase of serum alkaline phosphatase (ALP) activity alone in routine laboratory examinations, we picked up 76 new out-patients of adult within the two-fold high ALP level in contrast to the reference range in the Akita University Hospital for one year, and then studied the relation between the histories and serum ALPs of 33 patients whose ALP had increased pathologically or decreased after intervention such as surgical operations. The ratio of the patients with malignant tumors to the tested all patients was 13 to 76 (17%). Immunochemical analysis of sera for the cancers of the lung, larynx and prostate showed that the small amount of the placental isozyme or intestinal-like isozyme was expressed selectively. It may be useful for earlier detection of malignancy to analyze the cancer-associated ALPs, when the small and sequential increase of the serum ALP activity is found in routine laboratory examinations.

Aged↗
PubMed1999

[Changes in nitric oxide-related compounds in endotoxemic rats].

NO-related compounds in the blood of septic rats were examined by chemiluminescence method. Rats were treated with 5 mg/kg or 10 mg/kg lipopolysaccharides (LPS) and followed for 30 h. We have determined and evaluated the concentrations of the total NO-related compounds in whole blood (Total-NO), those in plasma (Plasma-NO) and membrane bound-NO (Membranous-NO) in erythrocytes from the LPS-challenged rats. 1) Levels of Plasma-NO after 3 h and Membranous-NO after 7 h in the rats were significantly increased, peaked at 14 h, and then restored to control levels at 30 h. 2) At 7 h in the rats, latter NO levels were exhibited within 10 nM/mg protein. 3) The existence of Membranous-NO can be confirmed by the in vitro experiments of rat erythrocytes incubating with different NO-donors, NOC-3 or SIN-1. 4) Taken together, the determination of Membranous-NO may be an additional marker for pathophysiological states of septic stress.

Animals↗
PubMed1999

[Expression of reactive oxygen-related enzymes in human umbilical vein endothelial cells (HUVEC) cultured with high concentrations of glucose].

We examined the levels of reactive oxygen-related enzymes in human umbilical vein endothelial cells cultured with high concentrations of glucose, in vitro. From the results, elevated levels of catalase mRNA and its protein were exhibited in the presence of higher glucose. In addition, the message level of p22-phox as the active center of NADPH oxidase, was slightly increased. Taken together, the endothelial injury induced by diabetes may associated to the elevated level of O2- production. However, the level of catalase as .OH scavenger was mainly increased, cooperatively.

Cells, Cultured↗
PubMed1998

Changes in intestinal alkaline phosphatase isoforms in healthy subjects bearing the blood group secretor and non-secretor.

We found the high molecular mass intestinal alkaline phosphatase (HIAP) and normal molecular mass intestinal alkaline phosphatase (NIAP) in serum at fasting and after fatty meal by use of 6.0% polyacrylamide gel electrophoresis (PAGE) in the presence of 1% Triton X-100. HIAP only appeared in serum of Lewis blood group secretors ¿Le(a-b+)¿, and HIAP levels were dependent on ABO blood groups. Among the secretors, the highest activities of HIAP in fasting serum were observed in subjects with blood groups O and B (8.6+/-1.4 U/1; mean+/-SD) and the lowest activities were associated with blood group A (0.7+/-0.2 U/1; mean+/-SD), and the HIAP activities did not change after fatty meal. In contrast, NIAP was present in the serum of both secretors and non-secretors regardless of ABO blood group. Trace amounts of NIAP remained in fasting serum; however serum NIAP activities rose sharply after fatty meal. The remaining ratios of NIAP activity at fasting and 9 h after fatty meal of secretors were approximately the same as those of non-secretors. The electrophoretic mobility on PAGE or the apparent molecular mass estimated by gel filtration of serum NIAP in secretors was slightly different from that in non-secretors. In addition, HIAP can be normalized to NIAP on PAGE in the absence of Triton X-100, and the electrophoretic mobility of normalized-NIAP was identical to that of original NIAP in secretors. Accordingly, it can be concluded that the structure of serum NIAP in the secretor was different from that in the non-secretor, because HIAP is only formed by serum NIAP in the secretor. These results suggest that differences in serum NIAP in the secretor and the non-secretor may be closely related to the appearance of IAP in the circulation.

ABO Blood-Group System↗
PubMed1998

Partial breakdown of glycated alkaline phosphatases mediated by reactive oxygen species.

The lower levels of serum alkaline phosphatase (AP) activity found in patients with diabetes mellitus apparently originate from the selective disappearance or decrease in bone AP activity in the circulation. Hence, we investigated in vitro the effect of glycation on the activities of five AP isozymes. Aseptic incubation with 25 mmol/L of D-glucose and APs rapidly reduced bone and placental AP activities before those of liver, kidney and intestinal enzymes. The resulting bone and placental AP molecules were clearly glycated, according to the result of aminophenylboronic acid affinity chromatography. Furthermore, Western blotting analysis revealed that the placental AP molecule was fragmented, and its partial cleavage took place at Ala154 on the AP molecule. Since glycation of serum proteins causes the generation of reactive oxygen species, the effects of reactive oxygen species on placental AP activity were assayed, and the results indicated that hydroxyl radicals might be a major factor for the specific inactivation of AP activities. The reduction in AP activity by incubation with glucose in vitro was reversed by the further addition of catalase. Furthermore, ferrous ion with hydrogen peroxide, which generates hydroxyl radicals, had an inhibitory effect on AP activities. These findings suggest that the reduced AP activity in diabetic patients might result from partial cleavage of the bone AP molecule by reactive oxygen species induced by glycation.

Alkaline Phosphatase↗
PubMed1998

Bezafibrate has an antioxidant effect: peroxisome proliferator-activated receptor alpha is associated with Cu2+, Zn2+-superoxide dismutase in the liver.

Administration of bezafibrate in rats significantly reduced the levels of plasma thiobarbituric acid-reactive substances (TBARS) in comparison with those obtained in rats fed a soy or lard chow. Moreover, an elevation of in vitro conjugated diene production and linoleic acid levels in the high-density lipoproteins and low-density lipoproteins induced by a soy or lard chow, was reduced by bezafibrate administration. In addition, the liver Cu2+, Zn2+-superoxide dismutase (SOD) gene expression showed a significant positive correlation with the liver peroxisome proliferator-activated receptor alpha (PPARalpha) mRNA level (R=0.769, p<0.0001). This unique characteristic of bezafibrate, which possesses both a hypolipidemic effect and antioxidant activity, may be beneficial in preventing vascular complications in hyperlipidemia.

Acyl-CoA Oxidase↗
PubMed1998

Reduced alkaline phosphatase activity in diabetic rat bone: a re-evaluation.

We found previously that human bone alkaline phosphatase (AP) was glycated by aseptic incubation with glucose, and partially broken down by reactive oxygen species. In this study, we examined whether selective in vivo glycation of AP molecules occurred in bone tissue, using experimental diabetic rats induced by streptozotocin and spontaneously diabetic rats. Additionally, the effects of hyperlipidemia on bone AP activity were examined. Serum AP activity was significantly elevated after incipient onset of diabetes, and the increased activity originated from the intestinal isozyme. High levels of intestinal AP activity were also observed in rats with hyperlipidemia induced by feeding high-fat or high-fructose chow, but the AP activity in bone tissues was maintained at a constant level. AP activity in bone was reduced after the onset of diabetes. The resulting bone AP molecule bound to an aminophenylboronic acid column, which had affinity for glycated proteins, and contained smaller molecular sizes than the native bone AP. These results suggest that elevated levels of serum AP activity originated from the intestinal isozyme accompanied with hyperlipidemia induced by diabetes. In contrast, the reduced serum levels of AP activity in diabetic rats might be dependent on inactivation of bone AP, which was glycated, followed by partial breakdown of bone AP molecules, possibly due to reactive oxygen species.

Alkaline Phosphatase↗
PubMed1998

Properties of high-molecular-mass placental alkaline phosphatases in normal pregnancy sera.

We examined the appearance of high-molecular-mass placental alkaline phosphatases (HPLAPs) in the serum of normal pregnant women by means of polyacrylamide gel electrophoresis (PAGE) in the presence of Triton X-100. The HPLAPs were undetectable or only slightly detectable by PAGE in the absence of Triton X-100. The HPLAPs were detected in all sera sampled during the last trimester of pregnancy. The catalytic activities of total placental alkaline phosphatase (TPLAP) and HPLAPs were correlated (r = 0.96) and the ratio of HPLAPs/TPLAP catalytic activity was 0.20 (0.06) (mean and SD) in 40 serum samples from pregnant women. The HPLAPs appear to be formed from a common dimeric placental alkaline phosphatase (PLAP) (common-PLAP), as judged by the fact that they were formed again after removal of HPLAPs from serum by gel filtration. The formation of HPLAPs was more prominently observed with the faster fractions of gel filtration. The apparent molecular mass of the HPLAPs in pregnancy serum was 720 KDa by gel filtration. HPLAPs were not converted to common-PLAP by phosphatidylinositol-specific phospholipase (PIPL) C and PIPL-D treatments. The HPLAPs were selectively incorporated into liposomes consisting of phosphatidylcholine/cholesterol, and most of the PIPL-D-treated PLAP could from HPLAPs, while a small amount of PLAP could not form HPLAPs. On the other hand, HPLAPs in pregnant women's sera and HPLAPs prepared from partially purified PLAP in vitro could be converted to common-PLAP by brief treatment with subtilisin. However, the highly purified PLAP could not form HPLAPs in the presence of Triton X-100. These results suggest that PIPL-D-resistant and PLAP-associated serum protein may regulate the conversion of PLAP to HPLAP in the presence of Triton X-100.

Alkaline Phosphatase↗
PubMed1998

Enhanced activity of pyrimidine 5'-nucleotidase in rat red blood cells during erythropoiesis.

A nucleotidase that catalyzed selective hydrolysis of pyrimidine 5'-nucleotides was investigated in rat red blood cells (RBCs). The enzyme had similar catalytic properties to human pyrimidine 5'-nucleotidase I (P5N-I). The P5N-I deficiency was known to be closely correlated with the human inherited disease, non-spherocytic hemolytic anemia. Similar to the human P5N-I, the rat enzyme preferentially hydrolyzed 5'-(d)CMP and 5'-UMP but no reactivity was observed with any 3'-nucleotide. Molecular mass of the enzyme was estimated to be approximately 38 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis. Another subclass of pyrimidine 5'-nucleotidase, P5N-II, was also present in rat RBCs. This P5N-II-like enzyme, which resembled a 5'(3')-nucleotidase, preferentially hydrolyzed both 5'- and 3'- of (d)TMP or (d)UMP, but no cytosine nucleotide was hydrolyzed by the enzyme. Results from the reactivity with the antibody against rat 5'(3')-nucleotidase and estimated subunit molecular mass of the enzymes, about 26 kDa, suggested that the P5N-II-like enzyme had a similar structure to the 5'(3')-nucleotidase. The P5N-I-like activity in rat RBCs increased 5 to 6-fold at 4 days after phenylhydrazine injection, and reached a maximum at 6 to 7 days. No change in the activity of P5N-II-like nucleotidase was observed during the experimental period. The increase in rat P5N-I activity coincided with maturation of the erythrocytes.

5'-Nucleotidase↗
PubMed1997

Troglitazone has a scavenging effect on reactive oxygen species.

Troglitazone (CS-045), a newly developed antidiabetic thiazolidinedione that enhances insulin sensitivity, is similar in structure to several antioxidants, including alpha-tocopherol and probucol. The in vitro antioxidant activity of troglitazone has been demonstrated in alloxan-induced hyperlipoperoxidemic and hyperlipidemic mice. In this study, we found that troglitazone had a scavenging effect on reactive oxygen produced by xanthine-xanthine oxidase and generated by stimulated neutrophils and tends to be the radical form. Our results suggest that troglitazone is an antioxidant similar to alpha-tocopherol. However, under the same conditions, pioglitazone, another thiazolidinedione drug, did not have a scavenging effect. The antioxidant action of troglitazone, which is attributable to the similarity of its molecular structure to that of alpha-tocopherol, may be of benefit in preventing diabetic vascular complications, in addition to having hypoglycemic and hypolipidemic effects.

Antioxidants↗
PubMed1997

An assay method for nitric oxide-related compounds in whole blood.

Recent evidence suggests that nitric oxide (NO) generated in vivo will be converted into the forms of nitrite/nitrate, nitrosyl hemoproteins, nitrosyl metal complexes, and S-nitroso-compounds in the circulation. Nitrosothiols have also been reported to be relatively stable metabolites with micromolar levels in plasma. We hypothesized, therefore, that the determinations of all the NO-related compounds in blood would be of diagnostic significance. The assay method described here consists of the thermolysis of all the NO-related compounds in whole blood and the detection of resulting nitrate by fluorometry or chemiluminescence after an enzymatic reduction. S-Nitroso-albumin and nitrosyl hemoglobin can be easily thermolysed to nitrate, and relatively stable S-nitroso-glutathione is also degraded to nitrate in the presence of blood constituents with high molecular mass (above 30 kDa). Concentrations of NO-related compounds in blood from healthy human as well as control or lipopolysaccharide-stimulated rats were determined. We found that membrane-bound NO which showed the augmented levels under the pathophysiological states could also be detected. Together with electron spin resonance spectra, our data indicate that the fraction of NO diffused and metabolized within red cells and the other NO-metabolites in plasma such as nitrite/nitrate and S-nitroso-compounds, both of which can reflect NO-production in vivo, would be recovered and detected quantitatively by this method.

Animals↗