Biomedical subjects

Y S Kwon

Publications and source records attributed to Y S Kwon.

17 recordsLinked to original sources

PubMed2006

Use of silicone stents for the management of post-tuberculosis tracheobronchial stenosis.

The role of bronchoscopic management in post-tuberculosis tracheobronchial stenosis is not well defined. To investigate the role of bronchoscopic intervention, including silicone stenting, in the management of post-tuberculosis tracheobronchial stenosis, the current retrospective study was conducted at a tertiary referral hospital. Under rigid bronchoscopy, 80 patients underwent ballooning, neodymium-yttrium aluminium garnet laser resection and/or bougienation as first-line methods of airway dilatation between January 2000 and December 2003 inclusive, and were followed for a median of 41 months. Silicone stents were required in 75 out of 80 (94%) patients to maintain airway patency. Bronchoscopic intervention provided immediate symptomatic relief and improved lung function in 88% of the patients. After airway stabilisation, stents were removed successfully in 49 out of 75 (65%) patients at a median of 14 months post-insertion. Three patients out of 75 (4%) eventually underwent surgical management. Acute complications included: excessive bleeding (n = 1); pneumothorax (n = 5); and pneumomediastinum without mortality (n = 2). Stent-related late complications, such as migration (51%), granuloma formation (49%), mucostasis (19%) and re-stenosis (40%), were controllable during a median follow-up of 41 months. In conclusion, bronchoscopic intervention, including silicone stenting, could be a useful and safe method for treating post-tuberculosis tracheobronchial stenosis.

Adolescent↗

PubMed2005

An analysis of fishing vessel accidents.

In this paper, accident data collected from the Marine Accident Investigation Branch are presented and an analysis is carried out to determine the most common causes of accidents on fishing vessels. Discussions on fishing vessel-safety assessment and data problems are given.

Accidents, Occupational↗

PubMed2004

Selegiline potentiates the effects of EGb 761 in response to ischemic brain injury.

We evaluated whether combined treatment with selegiline, a selective MAO-B inhibitor, and EGb 761, a standard extract of Ginkgo biloba, has synergistic effects against ischemic reperfusion injury (IRI) in gerbils. Interestingly, we observed that pretreatment with EGb 761 significantly attenuated selegiline-induced hyperactivity. This finding paralleled striatal fos-related antigen immunoreactivity (FRA-IR) in mice. Four minutes of bilateral carotid artery occlusion caused substantial cell loss in the CA1 of the hippocampus 5 days post-ischemic insult. Pretreatment with EGb 761, with or without selegiline, significantly attenuated this neuronal loss. Combined treatment with EGb 761 plus selegiline was more efficacious in preventing this loss. Synaptosomal formations of protein carbonyl, lipid peroxidation (malondialdehyde (MDA) + 4-hydroxyalkenal (4-HDA)), and reactive oxygen species (ROS) in the hippocampus remained elevated 5 days post-ischemic insult. The antioxidant effects appeared to be most significant in the group treated with EGb 761 plus selegiline. This combined treatment produced more significant attenuation of IRI-induced alterations in intramitochondrial calcium accumulation, the mitochondrial transmembrane potential, and mitochondrial Mn-superoxide dismutase-like immunoreactivity (Mn-SOD-IR) than either treatment alone. Our results suggest that co-administration of EGb 761 and selegiline produces significant neuroprotective effects via suppression of oxidative stress and mitochondrial dysfunction without affecting neurological function.

Animals↗

PubMed2004

A database designed to computationally aid an experimental approach to alternative splicing.

A unique microarray approach has been developed to profile alternative splicing in the cell. To support the development of this approach, we have developed the Manually Annotated Alternatively Spliced Events (MAASE) database system, which is a unique alternative splicing information resource designed specifically with experimentalists in mind. MAASE is an online resource for the convenient access, identification, and annotation of alternative splicing events (ASEs). MAASE consists of two components: an annotation system and a curated database. The annotation system is a web-based workspace that combines manual and computational approaches to identifying and annotating ASEs, a combination that is vital if a comprehensive collection is to be obtained. The annotation system is publicly available and provides a scalable solution to acquiring as well as contributing to annotated ASEs. MAASE annotated ASEs are deposited into the database component, which can either be queried one entry at a time or multiple entries at a time with convenient access to alternatively spliced junctional and surrounding sequences to facilitate the design of microarray experiments.

Alternative Splicing↗

PubMed2001

Marker-assisted selection for identification of plant regeneration ability of seed-derived calli in rice (Oryza sativa L.).

Quantitative trait loci (QTL), associated with the ability of plant regeneration from seed-derived callus of rice, were mapped using a recombinant inbred (RI) population from Milyang 23/Gihobyeo. Each flanking marker, RZ474 and RZ575, tightly linked to two QTLs (qSGR-3-1 and qSGR-3-2) that are located on chromosome 3 was used in marker-assisted selection (MAS). These markers were tested on IR 36/MG RI036 (F3), Milyang 23/MG RI036 (F3), and forty-one rice cultivars. A restriction fragment length polymorphism (RFLP) marker, RZ575, that is located on chromosome 3 could effectively differentiate lines with high and poor regeneration ability, based on marker genotypes. This marker might be applicable for screening rice germplasms with high regeneration ability. Its introgression into elite lines might also be valuable in breeding programs to develop highly responsive genotypes to tissue culture.

Breeding↗

PubMed2001

Production of granular activated carbon from waste walnut shell and its adsorption characteristics for Cu(2+) ion.

Production of granular activated carbon by chemical activation has been attempted employing walnut shells as the raw material. The thermal characteristics of walnut shell were investigated by TG/DTA and the adsorption capacity of the produced activated carbon was evaluated using the titration method. As the activation temperature increased, the iodine value increased. However, a temperature higher than 400 degrees C resulted in a thermal degradation, which was substantiated by scanning electron microscopy (SEM) analysis, and the adsorption capacity decreased. Activation longer than 1h at 375 degrees C resulted in the destruction of the microporous structure of activated carbon. The iodine value increased with the increase in the concentration of ZnCl2 solution. However, excessive ZnCl2 in the solution decreased the iodine value. The extent of activation by ZnCl2 was compared with that by CaCl2 activation. Enhanced activation was achieved when walnut shell was activated by ZnCl2. Applicability of the activated carbon as adsorbent was examined for synthetic copper wastewater. Adsorption of copper ion followed the Freundlich model. Thermodynamic aspects of adsorption have been discussed based on experimental results. The adsorption capacity of the produced activated carbon met the conditions for commercialization and was found to be superior to that made from coconut shell.

Adsorption↗

PubMed2001

Quantitative trait loci mapping associated with plant regeneration ability from seed derived calli in rice (Oryza sativa L.).

Quantitative trait loci (QTLs), which are associated with the ability of plant regeneration from seed derived calli, were detected using a recombinant inbred (RI) population from a cross between 'Milyang 23 (toingil)' and 'Gihobyeo (japonica)' in rice (Oryza sativa L.). A tongil type cultivar, 'Milyang 23', has a lower frequency of callus induction and plant regeneration than those of japonica 'Gihobyeo'. Transgressive segregations were observed for the callus induction rate and plant regeneration ability from seed derived calli of the RI population. An interval mapping analysis was used to identify the QTL controlling the plant regeneration ability. Two QTLs for the callus induction rate were detected on chromosomes 1 and 2, explaining the 10.9% total phenotypic variation. Four QTLs that are associated with the plant regeneration ability were located on chromosomes 2, 3, and 11, accounting for 25.7% of the total phenotypic variation.

Chromosome Mapping↗

PubMed2001

Helicobacter pylori-associated iron-deficiency anemia in adolescent female athletes.

OBJECTIVE: The objective was to investigate the role of Helicobacter pylori infection in iron-deficiency anemia (IDA) of pubescent athletes. STUDY DESIGN: Blood sampling and a questionnaire survey were performed on 440 regular high school students and 220 athletes of a physical education high school. Hemoglobin, serum iron, total iron-binding capacity, ferritin, and immunoglobulin G antibody to H. pylori were measured to compare the prevalence of IDA and H. pylori infection in the groups. Nutritional analysis and a questionnaire survey for socioeconomic status were undertaken to compare and control for other risk factors that might influence IDA and H. pylori infection in the groups. In those with IDA coexistent with H. pylori infection, we also determined whether IDA can be managed by H pylori eradication. RESULTS: The prevalence rates of IDA, H pylori infection, and H. pylori -associated IDA in female athletes were higher than in the control group. The relative risk of IDA was 2.9 (95% CI, 1.5 to 5.6) for those with H. pylori infection. Athletes who exhibited H. pylori -associated IDA showed significant increases in hemoglobin, iron, and ferritin levels after H. pylori eradication. The subjects in the control group who were treated orally with iron alone showed no significant changes. CONCLUSION: Adolescent female athletes may have development of H. pylori -associated IDA, which can be managed by H. pylori eradication.

Adolescent↗

PubMed2001

Development of glaucoma in the course of interferon alpha therapy for chronic hepatitis B.

Previous reported ocular complications of interferon alfa administration are extremely rare. These include oculomotor palsy, corneal allograft rejection, retinal hemorrhage and cotton wool patches. A 15-year-old boy with chronic hepatitis B was treated with interferon alpha for six months, and then developed glaucoma. After the interferon therapy had been discontinued the glaucoma improved. Accordingly, we report a case of glaucoma development during the course of interferon alpha therapy for chronic hepatitis B.

Adolescent↗

PubMed1999

Bipartite modular structure of intrinsic, RNA hairpin-independent termination signal for phage RNA polymerases.

The phage SP6 RNA and T7 RNA polymerases, which are closely related to each other, intrinsically stop at two signals in the Escherichia coli rrnB terminator t1 through different mechanisms. The downstream signal functioned without an RNA secondary structure formation, in which the signal was still active when separated from the upstream, hairpin-forming signal, and IMP incorporation enhanced its efficiency. The sequence from -15 to -1 was essential for the downstream, hairpin-independent termination (at -1). The results of SP6 transcription with heteroduplex templates and ribonucleotide analogs suggested that the downstream signal consists of two functionally different modules. The effects of iodo-CMP or IMP incorporation into RNA on termination efficiency were not sensitive to incorporation at -9 and upstream, but they were reactive to incorporation at -6 and -2, as reflected by strong iodo-rC:dG and weak rI:dC base pairing. Thus, the downstream module (from -8 approximately -6 to -1) appears to facilitate the release of RNA. Mismatches in the templates at -6 to +1 allowed for efficient termination, unlike those upstream of the sequence. The upstream module (from -15 to -9 approximately -7) functions as a duplex. Pausing of the SP6 elongation complex at the termination site was detected when RNA release was suppressed by the incorporation of 5-bromo-UMP, and it was dependent on the upstream module. Results of single-round SP6 transcriptions using 3'-deoxynucleotides and immobilized templates indicated that RNA was not released from the elongation complexes halted at the termination site on the template variants carrying mutations in the upstream or downstream module, whereas such complexes on the wild type template were dissociated. Thus, halting or simple pausing was not sufficient for termination even when the downstream module was intact. The upstream module appears to mediate such conformation change necessary for termination.

Base Pairing↗

PubMed1999

Selection of RAPD marker for growth of seedlings at low temperature in rice.

We have developed a polymerase chain reaction (PCR)-based assay that could effectively reduce the time period required to screen and select the cold tolerance gene of rice seedlings under field conditions. The two specific random amplified polymorphic DNA (RAPD) fragments for the assay were identified on the basis of quantitative trait loci (QTL) analysis which were found to be tightly linked to cold sensitivity. The two RAPD fragments, OPT8(600) in the cold sensitivity rice cultivar 'Dular (indica)' and OPU20(1200) in the resistance rice cultivar 'Toyohatamochi (japonica)', were identified after screening 11 RAPD fragments using 2 random primers on the genomic DNAs of 'Dular' and 'Toyohatamochi'. These primers, when used in a multiplexed PCR, specifically amplified a 0.6 kb and a 1.2 kb fragment in the sensitive and resistant rice cultivars, respectively. When this assay was performed on the genomic DNAs of 16 japonica, 3 Tongil (indica/ japonica), and 2 indica rice cultivars, the primers amplified a 0.6 kb fragment in all of the cold sensitivity rice cultivars or 1.2 kb fragment in all of the resistance ones. These markers can be of potential use in the marker-assisted selection (MAS) for cold tolerance in rice seedling. As screening for resistance can now be conducted independent of the availability of low temperature, the breeding of cold tolerance cultivars can be hastened.

Acclimatization↗

PubMed1998

Viability of E. coli cells containing phage RNA polymerase and promoter: interference of plasmid replication by transcription.

Strong transcription of phage promoters often renders the host E. coli cells containing the phage RNA polymerase inviable. When expression of the phage SP6 RNA polymerase gene in one plasmid was induced in the E. coli JM109 cells, cells that bear an active SP6 promoter were inviable. When it was not induced (the polymerase was still produced in low levels), viability of the host cells and stability of the promoter-bearing plasmids depended on the orientation of the promoter with respect to that of the replication origin and on the sequence of the origin. A group of SP6 promoter-bearing plasmids (group I plasmids) that had the promoter directed towards the ColE1 replication origin, rendered the polymerase-containing host cells inviable in selective media. When the sequence of the origin was different (group II plasmids), this adverse effect was not observed. When the promoter direction was same as the replication origin and the ampicillin-resistant gene (group III plasmids), many satellites formed around the colonies on ampicillin-containing agar plates. These effects were caused by strong transcription of the phage SP6 promoter by its RNA polymerase, since they were reduced or eliminated by inserting an active terminator just downstream of the promoter. The viability of host cells and copy number of the promoter/terminator-bearing plasmids appear to be quantitatively related with efficiency of initiation and termination of the phage transcription. These systems may be useful for in vivo screening for mutant variants of the phage promoter, polymerase and terminator that are affected in their efficiency.

Bacteriophages↗

PubMed1998

In vitro stimulation of cumulus-cell expansion by human cord serum in mouse oocyte-cumulus complexes.

PURPOSE: The aim of this study was to test whether human cord serum (HCS) containing gonadotropins has an effect on the expansion of oocyte-cumulus complexes (OCCs). METHODS: The concentration of follicle stimulating hormone (FSH) and luteinizing hormone (LH) was measured in HCS by radioimmunoassay (RIA). After short-term culture (4 hr) with or without OCCs, medium containing 0.4% bovine serum albumin (BSA) as control or 10% HCS was collected and analyzed for its concentration of estradiol, progesterone, and testosterone. RESULTS: The FSH concentration was at the basal level, but the LH level was as high as 142.4 mIU/ml in both natured and denatured serum. Undetectable levels of steroids were observed in control media with or without OCCs. In contrast, a moderate amount of steroid hormones was detected in culture medium containing HCS. OCCs secreted a minute amount of steroid hormones in response to HCS. Similar patterns of cumulus expansion were observable by treatment with HCS, human chorionic gonadotropin (hCG), or HCS plus hCG after 4, 8, or 22 hr of culture. However, no cumulus expansion was observed in controls. CONCLUSION: These results suggest that LH in HCS induces cumulus expansion but does not affect the secretion of steroid hormones by OCCs during culture.

Animals↗

PubMed1997

Effect of a novel saponin adjuvant derived from Quillaja saponaria on the immune response to recombinant hepatitis B surface antigen.

Adjuvant activity of saponins extracted from the South American tree Quillaja saponaria has been demonstrated with many antigens. Recently, four saponin fractions (designated as QS-7, QS-17, QS-18, and QS-21) with adjuvant activity were purified by reverse phase chromatography. In particular, efficacy of the less toxic QS-21 fraction has been demonstrated with several recombinant viral antigens including HIV gp120. Here, we report a novel saponin fraction (designated as QS-L1) derived from Quillaja saponaria. Unlike previously identified saponins, QS-L1 had a different chemical structure and showed adjuvant activity only when administered in the presence of alum-precipitated antigen. Interestingly, the QS-L1 greatly increased not only a humoral immune response but also cellular immune response to recombinant hepatitis B virus surface antigen (HBsAg). Furthermore, QS-L1 showed lower toxicity in vivo and in vitro than the previously identified saponin fraction, QS-21. Finally, we examined the chemical structure of the QS-L1 using mass spectroscopic analysis, carbohydrate composition analysis and NMR spectroscopic analysis. Thus, our results indicated that this novel QS-L1 saponin fraction had several desirable properties required for an effective adjuvant.

Adjuvants, Immunologic↗

PubMed1997

Antimicrobial constituents of Angelica dahurica roots.

One novel coumarin from Angelica dahurica roots was elucidated to be 5,8-di(2,3-dihydroxy-3-methylbutoxy)-psoralen. It occurs together with six other known coumarins and ferulic acid. The antimicrobial activity of the coumarins and ferulic acid were compared.

Anti-Infective Agents↗

PubMed1989

[A study comparing the perception of patients, nurses and doctors about the educational needs of cancer patients].

Because of the advances in the treatment of cancer, patients live longer and require more comprehensive information in order to understand their illness, treatment procedure and role in the health care process. Each treatment involves combined therapeutic approaches, so information must be presented to the patient in such a way as to promote maximum understanding and acceptance. The purposes of this study were to explore and compare patients', nurses' and doctors' perception of the educational needs of cancer patients and to identify areas of agreement and disagreement in the perception of these needs by patients, nurses and doctors. Three groups took part in the study; 78 cancer patients, 39 nurses and 35 doctors. They all were selected from one general teaching hospital. Data were collected using a questionnaire, developed by the investigators. The questionnaire was made up of 2 sections; an importance rating scale and a knowledge/providing information rating scale. Each rating scale consisted of 20 specific informational items that were elicited through interviews with 60 cancer patients. The data were analyzed using percentages, means, Pearson correlation coefficients, t-test, and ANOVA. The results of this study were as follows; 1. Nurse subjects achieved a higher total score (85.6154) on the rating of importance than did the patients (81.5238) or the doctors (79.3125). The difference between the three group's total score was significant (F = 6.164, p less than .01) and the difference between the nurses' total score and doctors' was also statistically significant (t = 3.95, p less than .001). 2. On the whole, the rankings for the mean score of importance for the 20 items differed among the three groups of subjects. For the patient subjects, the highest mean ratings were for "the symptoms of recurring illness", "progress of illness", and "plan and duration of treatment" showing these to be the items that they considered important. The nurse subject felt that it was most important for oncology patients to know about "plan and duration of treatment", "how to minimize problems with loss of appetite, nausea, vomiting", and "amount of activity the patient can do around the work setting". Doctors felt it was most important for the patient to know about "prognosis of illness", "progress of illness", and "plan and duration of treatment". "Plan and duration of treatment" was the common item that all three groups perceived as important for patient learning.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗

PubMed1989

Severe visual impairment on a rehabilitation unit: incidence and implications.

Eleven of the first 191 admissions (5.8%) to a rehabilitation inpatient unit met the criteria for legal blindness; two additional patients (1%) had severe visual impairment (visual acuity above 20/200 but less than 20/70 with corrective lenses). All but three of these patients were ambulatory with a walkerette or cane when discharged to their homes. The commonest causes of blindness were macular degeneration, cataract, glaucoma, and diabetic retinopathy. Despite being older (mean age 79.7 years compared to 70.4 years for all 191 admissions) and having visual impairment superimposed on their primary rehabilitation diagnosis, these patients' lengths of stay (LOS) were not prolonged (mean LOS = 33.1 days compared to 35.9 days for all 191 admissions). It is concluded that severe visual impairment is not uncommon among rehabilitation inpatients, particularly those aged 70 or older. Health care professionals working in rehabilitation should become more familiar with, and proficient in, the basic principles and treatment techniques used in the rehabilitation of visually impaired persons.

Adult↗