Biomedical subjects

Y M Kwon

Publications and source records attributed to Y M Kwon.

36 records · Page 2Linked to original sources

PubMed1999

Hypotension induced by exercise is associated with enhanced release of adenyl purines from aged rat artery.

To determine whether the antihypertensive effects of exercise are associated with release of ATP and its metabolites from arteries, we assayed blood pressure and the release of adenine nucleotides and nucleosides from the caudal arteries of exercised and sedentary aged hypercholesterolemic rats. Exercise on a treadmill for 12 wk significantly decreased the rise in systolic and diastolic blood pressure by 7.5 and 15.9%, respectively, with advanced age. The concentrations of oleic, linoleic, and linolenic acids in the caudal artery decreased significantly with exercise, demonstrating an association between exercise and the unsaturation index of caudal arterial fatty acids. The amounts of total adenyl purines released by the arterial segments from exercised rats, both spontaneously and in response to norepinephrine, were significantly greater by 80.0 and 60.7%, respectively, than those released by tissues from sedentary rats. These results suggest that exercise alters the membrane fatty acid composition in aged rats as well as the release of ATP from vascular endothelial cells and that these factors are associated with the regression of the rise in blood pressure normally observed with advanced age.

Adenine Nucleotides↗

PubMed1999

Inhibitory effect of Cordyceps sinensis on spontaneous liver metastasis of Lewis lung carcinoma and B16 melanoma cells in syngeneic mice.

We investigated the effect of the water extract of Cordyceps sinensis (WECS) on liver metastasis of Lewis lung carcinoma (LLC) and B16 melanoma (B16) cells in mice. C57BL/6 mice were given a s.c. injection of LLC and B16 cells and sacrificed 20 and 26 days after tumor inoculation, respectively. WECS was daily administered p.o. to the mice in a dose of 100 mg/kg body weight (wt.) in the experiment of LLC and in a dose of 100 or 200 mg/kg body wt. in the experiment of B16 from one week before tumor inoculation to one day before the date of sacrifice. The tumor cells increased in the thigh in LLC-inoculated mice and in the footpad in B16-inoculated mice. The relative liver wt. of the tumor-inoculated mice significantly increased as compared to that of the normal mice due to the tumor metastasis, as verified by the hematoxylin-eosin staining pathological study in the LLC experiment. The relative liver wt. of the WECS-administered mice significantly decreased relative to that of the control mice in both the LLC and B16 experiments. WECS showed a strong cytotoxicity against LLC and B16 cells, while cordycepin (3'-deoxyadenosine), an active component of WECS, was not cytotoxic against these cells. These findings suggest that WECS has an anti-metastatic activity that is probably due to components other than cordycepin.

Animals↗

PubMed1999

Clinicopathologic characteristics of replication error-positive gastric carcinoma.

Microsatellite instability (MI), an expansion or contraction of microsatellites, is a manifestation of replication errors (RERs) that is recognized as performing an important role in carcinogenesis in a proportion of gastric carcinomas. We analyzed 96 cases of sporadic gastric carcinomas for the occurrence of MI in BAT-26 and other six microsatellite loci. Gastric carcinomas with BAT-26 alteration demonstrated a higher proportion of unstable loci in other examined microsatellites than did gastric carcinomas without BAT-26 alteration. We classified gastric carcinomas with BAT-26 alteration as RER+ and compared the RER status with their clinicopathologic features. Ten (10.4%) of 96 gastric carcinomas showed RERs: 2 (7.7%) of 26 early gastric carcinomas and 8 (11.4%) of 70 advanced gastric carcinomas were RER+. RER+ gastric carcinomas were significantly associated with older age, elevated gross type (Borrmann Type 2 or EGC IIa), expanding growth pattern (Ming's classification), and minimal desmoplasia. Although statistically not significant, RER+ gastric carcinomas showed more frequent intestinal type (Lauren's classification), more antral involvement, and lower lymph node metastasis than did RER- gastric carcinomas. There was no association between RER status and intratumoral lymphocyte infiltration or histologic differentiation. In conclusion, RER+ gastric carcinomas demonstrated distinct clinicopathologic features, and BAT-26 was a useful marker for assessing the RER status of gastric carcinomas.

Adult↗

PubMed1998

Molecular cloning and characterization of a plastid chaperonin 60 alpha subunit from Canavalia lineata.

A 2040 bp cDNA encoding plastid chaperonin 60alpha protein was isolated from a cDNA expression library prepared from Canavalia lineata leaves. The sequence analysis of the clone showed a significant homology to those of other plant plastid chaperonin 60alpha. The genomic DNA blot analysis indicated that Canavalia lineata chaperonin 60alpha is encoded by a single gene in the genome. The short-term kinetics of light on the gene expression revealed that the remarkable accumulation of the gene occurred after 24 h. The mRNA was also detectable in dark-grown seedling leaves.

Amino Acid Sequence↗

PubMed1998

Survival of a Salmonella typhimurium poultry isolate in the presence of propionic acid under aerobic and anaerobic conditions.

Propionic acid is commonly found as a fermentation product in the gastrointestinal tracts of food animals and has also been used to limit the microbial contaminants in animal feeds. Because propionic acid is known to have antibacterial activity, the propionic acid encountered by foodborne pathogens during their life cycles may play an important role in inhibiting the survival of the pathogens. The survival patterns of Salmonella typhimurium poultry isolate were determined both in aerobic and anaerobic tryptic soy broth (TSB; pH 5.0 or 7.0) containing various concentrations of propionic acid (0-200 mM). The levels of recovered cells were consistently greater at pH 7.0 compared to those at pH 5.0. For the first 4 days, the levels were significantly decreased by incubation under anaerobic conditions as compared to aerobic condition at pH 7.0 (P<0.05). However, there were fluctuations of cell populations with different patterns depending on both concentrations and growth conditions. To characterize the nature of the capability which allowed the cell multiplication following decreases in cell population during incubation at pH 7.0, the cells isolated from the outgrowth cultures were tested for survival in aerobic or anaerobic TSB (pH 5.0 or pH 7.0) containing propionic acid (50 mM). The outgrowth isolates did not show significant differences in the level of recovered cells in the presence of propionic acid when compared to the wild type strain (P>0.05), suggesting that the cells in the outgrowth cultures did not harbour mutation(s) conferring increased resistance to propionic acid. In addition, the level of recovered cells of isogenic rpoS mutant strain of S. typhimurium was not significantly different from that of the wild type strain in the same assay conditions (P<0.05). The results of this study show that the bactericidal activity of propionic acid on S. typhimurium can be affected by environmental conditions such as acidic pH levels and anaerobiosis in food materials and gastrointestinal tracts. However, S. typhimurium is also able to multiply in the presence of sublethal concentrations of propionic acid at neutral pH during prolonged incubation under both aerobic and anaerobic conditions.

Journal Article↗

PubMed1998

Purification of ornithine carbamoyltransferase from kidney bean (Phaseolus vulgaris L.) leaves and comparison of the properties of the enzyme from canavanine-containing and -deficient plants.

Kidney bean (Phaseolus vulgaris L.) ornithine carbamoyltransferase (OCT; EC 2.1.3.3) was purified to homogeneity from leaf homogenates in a single-step procedure, using delta-N-(phosphonoacetyl)-L-ornithine-Sepharose 6B affinity chromatography. The 8540-fold-purified OCT exhibited a specific activity of 526 micromoles citrulline per minute per milligram of protein at 35 degrees C and pH 8.0. The enzyme represents approximately 0.01% of the total soluble protein in the leaf. The molecular mass of the native enzyme was approximately 109 kDa as estimated by Sephacryl S-200 gel filtration chromatography. The purified protein ran as a single band of molecular mass 36 kDa when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and at a single isoelectric point of 6.6 when subjected to denaturing isoelectric focusing. These results suggest that the enzyme is a trimer of identical subunits. Among the tested amino acids, L-cysteine and S-carbamoyl-L-cysteine were the most effective inhibitors of the enzyme. The OCT of kidney bean showed a very low activity towards canaline. The OCTs of canavanine-deficient plants have very low canaline-dependent activities, but the OCTs of canavanine-containing plants showed high canaline-dependent activities. It was assumed that the substrate specificity of this enzyme determines the canavanine synthetic activity of the urea cycle.

Animals↗

PubMed1998

Long-term supplementation with a high cholesterol diet decreases the release of ATP from the caudal artery in aged rats.

We examined the effects of high cholesterol (HC) diet on the spontaneous and noradrenaline-induced release of ATP, ADP, AMP and adenosine from caudal arteries and on the plasma levels of these adenyl purines in aged (100-week-old) Wistar rats. Administration of this diet for 12 weeks significantly reduced spontaneous and noradrenaline (1 micromol/L)-evoked release of adenyl purines from the caudal arteries relative to rats given the control diet The unsaturation index of fatty acids (UI), which gives the average number of double bonds, of both the plasma and the caudal artery was significantly less in the HC diet-fed rats than in those fed the control diet. The HC diet for 12 weeks produced a slight but significant increase in systolic and diastolic blood pressure with advancing age. Regression analysis revealed a significant inverse relationship between the total amount of purines released from the artery and diastolic blood pressure, and also a positive relationship between the total amount of purines released and the UI of the caudal artery. These results suggest that the high cholesterol diet decreased the release of adenyl purines from the caudal arteries of aged rats, leading to an increase in blood pressure.

Adenosine↗

PubMed1998

Cortical tissue-specific accumulation of the root-specific ns-LTP transcripts in the bean (Phaseolus vulgaris) seedlings.

The characterization of a cDNA clone encoding non-specific lipid transfer protein (PvLTP, formerly named PVR3) in the roots of bean seedlings has been previously reported. In this study, we examined the temporal and spatial accumulation of PvLTP mRNA and the effect of the auxin naphthaleneacetic acid (NAA) on the accumulation of PvLTP mRNA during root development. In situ hybridization showed that accumulation of PvLTP mRNA is highly tissue-specific. Accumulation was detected in the cortical tissue, but not in other tissues of root, including the quiescent center and root cap. Within the cortical tissue, accumulation of PvLTP mRNA was developmentally regulated; accumulation of PvLTP mRNA was high in the cortical tissue of the proximal and ground meristem and declined as cortical tissue developed further. Since the appropriate distribution of auxin is an important factor responsible for the maintenance of root meristem organization. We examined effect of auxin on the accumulation of PvLTP mRNA in relation to the development of cortical tissue. In bean seedlings grown on medium supplemented with 5 microM NAA, morphological alternations, including radial root expansion and abnormal tissue organization in the root apical meristem, were observed. Only faint accumulation signals of PvLTP mRNA were observed in the cortical tissue of proximal meristem region, indicating that cortical tissue development was repressed by exogenous NAA. However, our results suggest that the change in accumulation of PvLTP mRNA is not direct regulatory effect but reflective effect of altered development of cortical tissue that was induced by exogenous NAA. The temporal and spatial accumulation of PvLTP mRNA indicates that PvLTP is a useful marker for the development of cortical tissue in the root tip in bean seedlings.

Carrier Proteins↗

PubMed1998

Induction of acid resistance of Salmonella typhimurium by exposure to short-chain fatty acids.

Exposure to short-chain fatty acids (SCFA) is one of the stress conditions Salmonella typhimurium encounters during its life cycle, because SCFA have been widely used as food preservatives and SCFA are also present at high concentrations in the gastrointestinal tracts of host animals. The effects of SCFA on the acid resistance of the organism were examined in an attempt to understand the potential role of SCFA in the pathogenesis of S. typhimurium. The percent survival of S. typhimurium at pH 3.0 was determined after exposure to SCFA for 1 h at pH 7.0. The percent acid survival, which varied depending on the SCFA species and the concentration used, was 42 after exposure to 100 mM propionate at pH 7.0 under aerobic incubation conditions, while less than 1% could survive without exposure. The SCFA-induced acid resistance was markedly enhanced by anaerobiosis (64%), lowering pH conditions (138% at pH 5.0), or increasing incubation time (165% with 4 h) during exposure to propionic acid. When protein synthesis during exposure to propionate was blocked by chloramphenicol, the percent acid survival was less than 1, indicating that the protein synthesis induced by exposure to propionate is required for the induction of the acid resistance. The percent acid survival determined with the isogenic mutant strains defective in acid tolerance response revealed that AtrB protein is necessary for the full induction of acid resistance by exposure to propionate, while unexpectedly, inactivation of PhoP significantly increased acid resistance over that of the wild type (P < 0.05). The results suggest that the virulence of S. typhimurium may be enhanced by increasing acid resistance upon exposure to SCFA during its life cycle and further enhanced by anaerobiosis, low pH, and prolonged exposure time.

Adaptation, Physiological↗

PubMed1996

Dietary cholesterol enhances impaired endothelium-dependent relaxations in aortas of salt-induced hypertensive Dahl rats.

We investigated the effect of hypercholesterolemia on the vascular reactivity of thoracic aortas isolated from hypertensive Dahl salt-sensitive (DS) rats. DS rats were fed on a low-sodium diet (control group), a low-sodium plus high-cholesterol diet (CHOL group), a high-sodium diet (NaCl group) or a high-sodium plus high-cholesterol diet (NaCl + CHOL group) for 8 weeks. Hypercholesterolemia developed in the CHOL and NaCl + CHOL groups, while hypertension developed in the NaCl and NaCl + CHOL groups, with these changes being greatest in the NaCl + CHOL group. Aortic cholesteryl ester accumulation was attenuated in the aortic rings from the NaCl and NaCl + CHOL groups, compared to the control group. The degree of attenuation in the NaCl + CHOL group was significantly greater than that in the NaCl group. Endothelium-dependent relaxations induced by the calcium ionophore A23187 were attenuated only in the NaCl + CHOL group. Endothelium-independent relaxations in response to sodium nitroprusside were slightly but significantly attenuated in the NaCl + CHOL group. The relaxations in the CHOL group were comparable to those in the control group. These findings indicate that cholesterol feeding strikingly enhances the impaired endothelium-dependent relaxations and the slightly impaired endothelium-independent relaxations in the aorta of DS rats with salt-induced hypertension, parallel to the development of hypertension, hypercholesterolemia and cholesterol deposition.

Acetylcholine↗

PubMed1996

Characterization of a cDNA encoding a proline-rich 14 kDa protein in developing cortical cells of the roots of bean (Phaseolus vulgaris) seedlings.

A cDNA clone, corresponding to mRNAs preferentially expressed in the roots of bean (Phaseolus vulgaris L.) seedlings, was isolated. This clone contains a 381 bp open reading frame encoding a polypeptide of 13.5 kDa, designated PVR5 (Phaseolus vulgaris root 5). The amino acid sequence of this clone is rich in proline (13.5%) and leucine (12.7%) and shares significant amino acid sequence homology with root-specific and proline-rich proteins from monocots (maize and rice), and proline-rich proteins from dicots (carrot, oilseed rape, and Madagascar periwinkle). The precise biological roles of these polypeptides are unknown. PVR5 mRNA accumulation is developmentally regulated within the root, with high levels at the root apex and declining levels at distances further from the root tip. In situ hybridization shows that PVR5 mRNA specifically accumulates in the cortical ground meristem in which maximal cell division occurs. Southern blot analysis suggests that genomic DNA corresponding to PVR5 cDNA is encoded by a single gene or a small gene family.

Amino Acid Sequence↗

PubMed1996

Cigarette smoke-modified low density lipoprotein impairs endothelium-dependent relaxation in isolated rabbit arteries.

1. We investigated the effects of cigarette smoke-modified low-density lipoprotein (CS-LDL) on endothelium-dependent relaxations in various isolated rabbit arteries, and compared them with those of oxidized LDL (Ox-LDL). 2. In aorta rings, acetylcholine-induced endothelium-dependent relaxations were attenuated by preincubation with CS-LDL and Ox-LDL. Endothelium-independent relaxations induced by sodium nitroprusside were not modified. Similar changes were observed in rings of coronary and basilar arteries. 3. These findings indicate that CS-LDL, as well as Ox-LDL, may decrease the release or activity of endothelium-derived relaxing factor in vascular endothelial cells.

Acetylcholine↗

PubMed1996

A novel extensin gene encoding a hydroxyproline-rich glycoprotein requires sucrose for its wound-inducible expression in transgenic plants.

A novel hydroxyproline-rich glycoprotein (SbHRGP3) that consists of two different domains is encoded by an extensin gene from soybean. The first domain (domain 1) located at the N terminus is composed of 11 repeats of Ser-Pro4-Lys-His-Ser-Pro4-Tyr3-His, whereas the second domain (domain 2) at the C terminus contains five repeats of Ser-Pro4-Val-Tyr-Lys-Tyr-Lys-Ser-Pro4-Tyr-Lys-Tyr-Pro-Ser-Pro5-Tyr-Lys-T yr- Pro-Ser-Pro4-Val-Tyr-Lys-Tyr-Lys. These two repeat motifs are organized in an extremely well-ordered pattern in each domain, which suggests that SbHRGP3 belongs to a new group of proteins having the repeat motifs of two distinct groups of dicot extensins. The expression of the SbHRGP3 gene increased with seedling maturation, and its expression was relatively high in the mature regions of the hypocotyl and in the root of soybean seedlings. An SbHRGP3-beta-glucuronidase (SbHRGP3-GUS) chimeric gene was constructed and expressed in transgenic tobacco plants. The expression of the SbHRGP3-GUS gene was not induced by wounding alone in transgenic tobacco plants; sucrose was also required. Expression was specific to phloem tissues and cambium cells of leaves and stems. In transgenic tobacco seedlings, SbHRGP3-GUS gene expression was activated by the maturation of the primary root and then inactivated; however, reactivation was specifically at the epidermis of the zone from which the lateral root was to be initiated. Its reactivation occurred just before the lateral root initiation. These results indicate that the SbHRGP3 gene in different tissues responds to different signals.

Amino Acid Sequence↗

PubMed1989

[Case report of the Sturge-Weber syndrome with intraoral finding].

The authors observed a 20-year-old female patient who had come to Department of Dentistry, Kyungpook National University Hospital due to the chief complaints of gingival enlargement and pain on the upper jaw. We performed the clinical, hematologic and radiologic examinations for the patient and obtained the following results; 1. We observed a nevus flammeus on the right side of the facial area, soft palate and buccal mucosa. 2. The enlargement of the upper and lower gingiva, we thought, was due to inflammatory reaction. 3. The above clinical signs were found in accordance with the maxillary and ophthalmic branch of trigeminal nerve. 4. The maxillary sinus was enlarged in Water's view. 5. Finally, we have reached the diagnosis of Sturge-Weber syndrome for the patient.

Adult↗

PubMedDate not supplied

Both extracellular ATP and shear stress regulate the release of nitric oxide in rat caudal artery.

1. To elucidate the physiological role of nitric oxide (NO) in regulating vascular tone, the effects of NG-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, on the vasoconstrictor response to noradrenaline (NA) in rat caudal artery was examined. 2. NG-Nitro-L-arginine methyl ester significantly potentiated the NA-induced increase in perfusion pressure in the perfused caudal artery, but did not affect the NA-induced contraction in caudal artery ring preparations. In addition, an increase in perfusion pressure mechanically produced by a stepwise increase in flow rate was not affected by L-NAME. 3. Noradrenaline evoked a significant increase in the release of endogenous ATP and its metabolites from the perfused artery, whereas increased perfusion pressure as a result of increased flow rate did not evoke release of endogenous ATP. 4. In the presence of exogenously applied ATP, L-NAME significantly potentiated the increase in perfusion pressure produced by increased flow rate. 5. These results indicate that perfused vascular tone is regulated by endogenous NO and suggest that extracellular ATP may participate in the synthesis and release of NO by shear stress in endothelial cells in the rat caudal artery.

Adenosine Triphosphate↗

PubMedDate not supplied

Antihypertensive effect of all-cis-5,8,11,14,17-icosapentaenoate of aged rats is associated with an increase in the release of ATP from the caudal artery.

Fish oils have been shown to lower blood pressure in hypertensive subjects. All-cis-5,8,11,14,17-icosapentaenoate (EPA), one of the omega-3 polyunsaturated fatty acids, is known to be one of the major active components in fish oil that has beneficial effects on the cardiovascular system. However, little is known about the antihypertensive effect of EPA alone on blood pressure. In the present study, we have determined the spontaneous and noradrenaline-evoked release of ATP, ADP, AMP, and adenosine from caudal arteries of aged (100 weeks old) Wistar rats which were fed a standard diet or a high cholesterol diet, treated with EPA. Dietary EPA administration increased plasma and caudal arterial EPA concentrations and repressed increases in blood pressure with advancing age in both aged rats with and without hypercholesterolemia. In addition, noradrenaline (1 micromol/l) evoked a significantly greater release of purines from the caudal arteries of EPA-administered aged rats compared to both sets of control rats. Regression analysis revealed a significant relationship between the total amount of purines released from the artery and blood pressure. These results suggest that administration of EPA to aged rats increases the release of ATP from the vascular endothelial cells, leading to repression of the blood pressure rise seen with advancing age.

Adenine Nucleotides↗

PubMedDate not supplied

Regional differences in noradrenaline-induced release of adenosine triphosphate from rat vascular endothelium.

We examined the release of endogenous adenyl purines such as adenosine triphosphate (ATP), ADP, AMP and adenosine from the caudal artery (CA), saphenous artery (SA), renal artery (RA), mesenteric artery (MA), pulmonary artery (PA) and thoracic aorta (TA) of rats, using high-performance liquid chromatography fluorescence detection. Noradrenaline induced the release of adenyl purines from these blood vessels. The total amount of adenyl purines release induced by noradrenaline from the CA was considerably larger than that from the TA. The rank order of the amount of adenyl purines released from the six blood vessels was CA>SA>RA>MA>PA> or =TA. The noradrenaline induced release of adenyl purines from the CA was significantly reduced by the removal of the endothelium. Noradrenaline also induced the release of adenyl purines from cultured endothelial cells of the CA and TA. The total amount of adenyl purines released from the former blood vessel was much larger than that from the latter. These results suggest the existence of vascular endothelial cells that are able to release ATP by an alpha1-adrenoceptor mediated mechanism, and that these cells are not homogeneously distributed in the vasculature.

Adenosine Triphosphate↗

PubMedDate not supplied

Cosmetic results of supracondylar osteotomy for correction of cubitus varus.

From 1984 to 1995, 19 patients with cubitus varus resulting from supracondylar humeral fractures underwent lateral closing-wedge osteotomies at The Royal Alexandra Hospital for Children. As the indication for osteotomy in all cases was the cosmetically unacceptable cubitus varus, we reviewed the cosmetic results. Seventeen patients were available for review. Subjective reports from patients and parents, as well as objective clinical assessment by one of the authors, were used to assess these results. According to our grading system, 12 (76%) patients had excellent results. These patients and their parents were satisfied with the cosmetic results, and there was no clinical evidence of a bony prominence over the lateral condylar region or an unsightly operative scar. One patient had a poor result with a lateral bony prominence and an unsightly scar, both of which were clinically obvious. We report that lateral closing osteotomies in children who have not yet reached skeletal maturity produce excellent cosmetic results.

Child↗