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Biomedical subjects

O J Kwon

Publications and source records attributed to O J Kwon.

At least 19 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↗
PubMed2006

Pulmonary TB and NTM lung disease: comparison of characteristics in patients with AFB smear-positive sputum.

OBJECTIVE: To compare the clinical and radiographic features of pulmonary tuberculosis (PTB) and non-tuberculous mycobacteria (NTM) lung disease in patients with acid-fast bacilli (AFB) positive sputum specimens. DESIGN: The initial clinical and radiographic features of 229 PTB patients were compared with those of 70 patients with NTM lung disease. The most commonly involved organisms in the NTM lung disease cases were Mycobacterium avium complex (n = 38, 54%) and M. abscessus (n = 26, 37%). RESULTS: Clinical and radiographic findings that were more common in patients with NTM lung disease than in PTB patients were: older age (P < 0.001), non-smoker (P < 0.001), history of previous TB treatment (P < 0.001), absence of pleural effusion (P = 0.017), involvement of middle and/or lower lung zones (P = 0.007), and bilateral disease (P = 0.005). Multivariate analysis showed that older age (> or = 40 years), non-smoker, previous TB treatment, absence of pleural effusion and involvement of middle and/or lower lung zones were significant independent predictors for NTM lung disease. CONCLUSIONS: There is considerable overlap in the clinical and radiographic appearances of PTB and NTM lung disease. The isolation and identification of causative organisms are mandatory for a correct diagnosis in patients with AFB-positive sputum specimens.

Coloring Agents↗
PubMed2005

Long-term graft outcome of living donor renal transplantation: single center experience.

UNLABELLED: The number of potential renal transplant recipients far exceeds the number of cadaveric donors. For this reason, living-related donors (LRD) and living-unrelated donors (LURD) have been used to decrease the cadaveric donor shortage. We analyzed 571 living donor transplants for 25 years in our center. MATERIALS AND METHODS: From 1978 to 2003, 571 patients underwent LRD (n = 253), or LURD (n = 318) kidney transplantation. The patients were divided into precyclosporine era (from 1978 to 1987, n = 44; era I), cyclosporine era (from 1988 to 1997, n = 367, era II), and cyclosporine plus mycophenolate-mofetil era (from 1998 to 2003, n = 160, era III). We compared the graft survival rate of the recipients according to the immunosuppressants, analyzing the variables of donor and recipient age, sex, HLA matching, and acute rejection rate. We also compared long-term survival rates between LRD and LURD. RESULTS: The 1- and 10-year graft survival rates of all patients were 93.4% and 77.4%, respectively. The 1- and 10- year graft survival rates were 75.0% and 36.3% in era I; and 94.8 % and 80.2% in era II. The 1- and 5-year graft survival rates were 96.6% and 93.3% in era III (P < .001). The occurrence rate of an acute rejection episode was 11.4% (era I), 21.8% (era II), and 14.4% (era III) (P = .056). The 1- and 5-year graft survival rates were 92.3% and 81.7% among LRD transplants, and 94.2% and 86.9% among LURD transplants, respectively (P = .122). DISCUSSION: The graft survival rates of living-donor transplants are improving due to advances in patient care and new immunosuppressive agents.

Cyclosporine↗
PubMed2005

The impact of gender and age matching for long-term graft survival in living donor renal transplantation.

UNLABELLED: In renal transplantation, donor age and allograft size are known to have an important influence on the outcome of the graft reflecting functional renal mass. Women tend to have smaller kidneys with 17% fewer nephrons than male kidneys. The number of glomeruli per kidney as well as the mean glomerular volume closely correlate with kidney weight and negatively correlate with subject age. We evaluated the impact of gender and age matching in living-donor renal transplantation on long-term graft survival. MATERIALS AND METHODS: Four groups were discerned among 614 renal transplants, according to donor and recipient gender: Group 1 was male donor to male recipient; Group 2 was male donor to female recipient; Group 3 was female donor to male recipient; and Group 4 was female donor to female recipient. We analyzed long-term graft survival and risk factors between the four groups as well as according to age matching. Statistical significance was determined by the Kaplan-Meier method and log rank test (P < .05). RESULT: The graft survival rates at 1, 3, 5, and 10 years were 92.62%, 88.13%, 82.37%, and 76.07%, respectively. The risk factors affecting long-term graft survival were donor age, donor gender, acute rejection rate, and HLA-DR matching. Among the four groups, the graft survival rates of Group 3 (female donor to male recipient) were significantly different from the other groups (P = .0165). Also, the long-term graft survival rates according to age differences were significantly different between older donors than recipients and younger donors than recipients in each group (P = .0213). CONCLUSION: The importance of inadequate renal mass is magnified in high-risk recipients. Age matching could perhaps improve the results of transplantation, particularly when kidneys from older donors are used. Consideration of age and gender as criteria for the choice of donors and recipients may be considered in organ allocation.

Adult↗
PubMed2005

Analysis of allograft biopsy specimens in renal transplants with proteinuria: is proteinuria a culprit of graft loss?

It has been proposed that proteinuria occurring after renal transplantation may be not only a marker but also a culprit of allograft dysfunction. We retrospectively analyzed the data from 55 patients who underwent transplant renal biopsy for proteinuria and/or azotemia occurring beyond 1 year after transplantation. Proteinuria was considered as significant when > or = 30 mg/dL, and the results of transplant biopsy were categorized according to the Banff 97 classification. Logistic regression was used to estimate odds ratios (OR) for graft loss associated with proteinuria and transplant pathology. The patients were followed for 86.0 +/- 32.8 months after transplantation, and transplant biopsy was performed at 54.1 +/- 31.0 months. Proteinuria at 1 year after transplantation noted in 29.1% of patients was not significantly associated with graft loss (OR = 1.94, 95% CI from 0.59 to 6.41). In addition, proteinuria at the time of transplant biopsy was not significantly associated with graft loss. Chronic allograft nephropathy was the most frequent transplant pathology. Only glomerulonephritis was significantly associated with proteinuria at the time of the transplant biopsy. On the other hand, graft loss was significantly associated with the presence of proteinuria both at 1 year after transplant biopsy and at the final follow-up. These results suggest that posttransplantation proteinuria is an important marker of graft dysfunction, but is not predictive of graft loss in biopsy-proven cases. Appropriate management guided by the results of a transplant biopsy may improve the outcome.

Biopsy↗
PubMed2005

Recovery rate of NTM from AFB smear-positive sputum specimens at a medical centre in South Korea.

OBJECTIVE: To investigate the recovery rate of non-tuberculous mycobacteria (NTM) from acid-fast bacilli (AFB) smear-positive sputum specimens at a tertiary care medical centre in South Korea with a high pulmonary tuberculosis (PTB) burden. DESIGN: Retrospective analysis of data from AFB smear- and culture-positive sputum specimens collected between January 1998 and December 2001. RESULTS: Over 4 years, 1328 sputum specimens collected from 616 patients were AFB smear- and culture-positive. NTM were recovered from 9.1% (121/1328) of the smear-positive sputum specimens, and from 8.1% (50/616) of patients with smear-positive sputum. NTM were isolated at least twice in 94% (47/50) of the patients from whom NTM was recovered. The most common organism found was Mycobacterium avium complex, followed by M. abscessus. CONCLUSION: These results suggest that a substantial proportion of patients at a tertiary care medical centre in South Korea with AFB smear-positive sputum specimens may have NTM lung disease rather than PTB.

Adult↗
PubMed2004

The impact of sex and age matching for long-term graft survival in living donor renal transplantation.

BACKGROUND: Deficient functional renal mass leads to progressive renal injury owing to the detrimental effects of glomerular hyperfiltration. Therefore, renal transplant mass is an important determinant of outcome. MATERIALS AND METHODS: We retrospectively analyzed 614 living donor renal transplantations performed from 1979 to 2002. Patients were divided into 4 groups according to donor-recipient gender differences: group 1 (male to male), group 2 (male to female), group 3 (female to male), and group 4 (female to female). We analyzed the clinical and immunological data to compare the 4 groups with respect to long-term graft survival, age gender, acute rejection episodes an HLA matching. We used the Kaplan-Meier method with the log-rank test to assess graft survival. RESULTS: The actuarial graft survival rate was 86.24% at 5 years for donors younger than 50 years of age compared with 73.15% for those older than 50 years (P = .0000). The graft survival from younger donors than recipients was 85.23% at 5 years compared with 80.35% for older donors (P = .0213). The graft survival of group 3 (female donor to male recipient) was 75.12% at 5 years compared with 85.72%, 85.33%, and 83.16% for groups 1, 2, and 4, respectively (P = .0165). The main parameters significantly associated with graft survival were donor age (P = .0000), acute rejection episode (P = .0000), donor gender (P = .0215). HLA-DR matching (P = .0516), and donor and recipient age matching (P = .0213). CONCLUSIONS: The results suggest that the sex and age matching between donors and recipients should be considered as a criterion in the choice of donor and recipient pairs for living donor renal transplantation.

Actuarial Analysis↗
PubMed2004

The impact of donor and recipient age on the outcome of kidney transplantation.

BACKGROUND: As survival has improved in the general population over the last few decades, the age of patients participating in renal transplantation has also increased. This study sought to investigate the impact of donor and recipient age as predictors of long-term graft survival in renal transplantation. MATERIALS AND METHODS: We analyzed transplantation outcomes in 598 patients who received renal transplants from 1979 to 2002. Patients were divided into 4 groups according to their age at renal transplantation. Group A (donor age <50 years, recipient age >50 years, n = 19/3.2%); group B (donor age >50 years, recipient age <50 years, n = 153/25.5%); group C (donor age <50 years, recipient age >50 years, n = 69/11.6%), and group D (donor age <50 years, recipient age <50 years, n = 357/59.8%). Univariate analysis to assess the effect of donor and recipient age as predictor factors of graft outcome was complimented by Kaplan-Meier and log-rank methods to assess graft survival with P < 1.05 considered significant. RESULTS: In the elderly donor group, graft survival was 92.8% at 1 year and 85.6% at 3 years; in the younger donor group, they were 93.4% and 90.2%, respectively, a difference that was statistically significant (P = .02). Univariate analysis of age factors showed a significant reduction in graft survival among recipients who received kidneys transplants from donors older than 50 years, although recipient age >50 years was not found to be an independent risk factor. The incidence of acute rejection was 24.6% in the elderly donor group and 23.5% in the younger donor group (P = not significant). Among the 4 groups, the best result was group D with 1-year and 3-year graft survival rates of 93.3% and 90.5%, respectively, but this result was not statistically significant. CONCLUSIONS: These results may help the design for transplantation strategies for kidneys procured from elderly donors and for allocation to elderly recipients.

Adult↗
PubMed2001

Distribution of B/K protein in rat brain.

B/K protein is a recently isolated member of the double C2-like-domain protein family, which is highly abundant in rat brain. We generated high-titer rabbit polyclonal antibodies with specificity to the 55-kDa rat B/K protein, and examined the expression pattern of B/K protein in rat brain using an immunohistochemical staining method. Immunoreactivity to B/K protein was widely found in distinct regions of rat brain: strongly in the hypothalamus, most of the circumventricular organs, the locus coeruleus, the A5 neurons of the pons, and the anterior pituitary; moderately in the anterior olfactory nucleus, the raphe nucleus, the subfornical organ, and the median eminence; and faintly in the olfactory bulb, the telencephalon, the substantia nigra pars compacta, and the ventral tegmental area. In contrast, immunoreactivity to B/K protein was not observed in the thalamus, the cerebellum, the posterior pituitary, or the spinal cord. In most of the B/K-expressing neurons, immunoreactivity was expressed mainly in soma but not in nerve fibers. B/K was also expressed in nonneuronal cells such as the tanycytes and the subcommissural organ. In the vasopressin-secreting supraoptic and paraventricular nuclei of the hypothalamus, the site where B/K cDNA was originally isolated from, all of the neurons showing vasopressin immunoreactivity also expressed B/K protein, suggesting an overlap of their expression patterns.

Age Factors↗
PubMed2001

Immunogenetics of HLA class II in Israeli Ashkenazi Jewish, Israeli non-Ashkenazi Jewish, and in Israeli Arab IDDM patients.

The distribution of HLA class II alleles and genotypes in IDDM patients was examined in the three main Israeli ethnic groups: Ashkenazi Jews, non-Ashkenazi Jews, and Arabs. Molecular sequence specific oligonucleotide probe analysis was performed for DRB1, DQA1, and DQB1 genes. The DRB1*03011, DQA1*05 DQB1*02/DRB1*0402, DQA1*03, DQB1*0302 genotype was found to be the main susceptibility genotype in all three groups, with differences in the degree of association. In addition to DRB1*0402 (more frequent among Ashkenazi Jews), DRB1*0405, another subtype of DRB1*04, was found to be more prevalent among non-Ashkenazi Jews and Arabs. Many alleles were found to be negatively associated with insulin dependent diabetes mellitus (IDDM). This could be a result of the high frequency of susceptible alleles, or of linkage disequilibrium to a primary negatively associated allele. The strongest negative association was observed for DQB1*0301 in all three ethnic groups. The alleles DRB1*1401, DRB1*1501, DQB1*05031, DQB1*0602, and DQB1*0609 were not detected in any of the 202 IDDM patients, and are probably either strongly protective or in linkage with such alleles. Despite the differences found between the three ethnic groups, an overall analysis shows that the DRB1*04 alleles that account for susceptibility to IDDM in the Israeli population (DRB1*0402 and *0405) are the same as those responsible for susceptibility to IDDM in a number of other Mediterranean populations. In contrast, the susceptible allele in most Caucasian populations is DRB1*0401. It is noteworthy that the susceptible alleles DRB1*0402/05 for Mediterranean and DRB1*0401 for Caucasian populations are also frequent in the respective healthy populations. These findings support the results obtained in other studies, which point to a genetic relationship between the Israeli and Mediterranean populations.

Alleles↗
PubMed2001

Inactivation of catalase and superoxide dismutase by singlet oxygen derived from photoactivated dye.

Both superoxide dismutase (SOD) and catalase are key enzymes in the antioxidant system of the cells that work to maintain low steady-state concentrations of the reactive oxygen species. When exposed to a singlet oxygen-producing system composed of dye, such as methylene blue or rose bengal, and visible light both SOD and catalase were susceptible to oxidative modification and damage as indicated by the loss of activity, fragmentation and aggregation of peptide as well as by the formation of carbonyl groups. Histidine, a powerful quenching agent for singlet oxygen, and the polyamines, such as spermine and spermidine, were effective at protecting the activity loss mediated by illuminated dye, whereas spin traps were only mildly effective. The structural alterations of modified enzymes were indicated by the increase in susceptibility to proteases, the change in absorption spectra and in fluorescence spectra. The singlet oxygen-mediated damage to SOD and catalase may result in the perturbation of cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.

Animals↗
PubMed2001

Ceruloplasmin enhances DNA damage induced by cysteine/iron in vitro.

Ceruloplasmin (Cp) was found to promote the oxidative damage to DNA in vitro, as evidenced by the formation of 8-hydroxy-2'-deoxyguanosine and strand breaks, when incubated with a cysteine metal-catalyzed oxidation system (Cys-MCO) comprised of Fe(3+), O(2), and cysteine as an electron donor. The capacity of Cp to enhance oxidative damage to DNA was inhibited by hydroxyl radical scavengers such as sodium azide and mannitol, a metal chelator, diethylenetriaminepentaacetic acid, a spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and catalase. Ceruloplasmin also caused the two-fold enhancement of a mutation in the pUC18 lacZ' gene in the presence of Cys-MCO when measured as a loss of alpha-complementation. Incubation of Cp with Cys-MCO resulted in an increase in the content of carbonyl groups and the significant alteration of the ferroxidase activity, as well as the proteolytic susceptibility. The deoxyribose assay and the salicylate hydroxylation assay showed that hydroxyl free radicals were generated in the reaction of Cp with Cys-MCO. The release of a portion of Cu from Cp was observed, and conformational alterations were indicated by the changes in fluorescence spectra. Based on these results, we interpret the enhancing effect of Cp on DNA damage and mutagenicity induced by Cys-MCO as due to reactive oxygen species, probably hydroxyl free radicals, formed by the reaction of free Cu(2+), released from oxidatively damaged Cp, and H(2)O(2) produced by Cys-MCO. The release of Cu from Cp during oxidative stress could enhance the formation of reactive oxygen species and could also potentiate cellular damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

Large cell neuroendocrine carcinoma of the lung: clinical, CT, and pathologic findings in 11 patients.

The purpose of this study was to describe the clinical, computed tomographic (CT), and pathologic findings of large cell neuroendocrine carcinoma (LCNEC) of the lung. CT and pathologic findings as well as clinical features of surgically proven LCNEC of the lung were reviewed retrospectively in 11 consecutive patients (eight men and three women; mean age, 63 years; range, 44-77 years). Chest CT showed peripheral mass or nodule (n = 8) and central mass with distal atelectasis (n = 3). Six tumors were accompanied by mediastinal (n = 3) and hilar (n = 3) lymph node enlargement at CT. On pathologic examination, all resected tumors showed necrosis of variable extent (mean: 38%, range; 10-70%). The areas of intrinsic lipoid pneumonia and tumor emboli in two patients appeared at CT as areas of ground-glass opacity surrounding the tumor. Mediastinal nodal metastases were seen in three (27%) patients. Pathologic staging of 11 patients was IB in six, IIA in one, IIB in one, IIIA in two, and IIIB in one. Follow-up data showed extrathoracic metastases in four patients at mean follow-up period of 15 months. One patient died of distant metastasis 5 months after the surgery. CT findings of LCNEC of the lung are nonspecific and similar to those of other non-small cell lung cancers and extrathoracic metastasis is seen in approximately one third of the patients with follow-up study.

Adult↗
PubMed2001

Type 1 diabetes environmental factors and correspondence analysis of HLA class II genes in the Yemenite Jewish community in Israel.

OBJECTIVE: The Israeli Yemenite Jewish community has displayed an exceptionally rapid increase in the frequency of type 1 diabetes, having the highest rate of all Israeli ethnic groups. We studied the role of the environment, in relation to the nature and frequency of HLA class II genes, to evaluate its possible involvement in the development of diabetes. RESEARCH DESIGN AND METHODS: We interviewed 196 elderly Yemenite women, who had immigrated to Israel as adults, in programmed encounters about signs and symptoms of type 1 diabetes, infant feeding customs, and infectious diseases in Yemen. We also performed HLA oligotyping of DRB1, DQA1, and DQB1 genes in 120 unrelated Yemenite Jews, including 44 type 1 diabetic patients and 76 healthy control subjects, and used these data in correspondence analysis comparing Yemenites with different Israeli ethnic groups. RESULTS: Interviews indicated that early exposure to cow's milk was very common in Yemen. However, none of the women could recall classical presentations of diabetes. HLA oligotyping showed that gene frequencies of non-Asp-57 (of the HLA-DQB chain) in the patients (0.94) and control subjects (0.6) were similar to those of other populations with a known high incidence of type 1 diabetes. Correspondence analysis revealed that Yemenite Jews are genetically distinct from other ethnic groups in Israel. CONCLUSIONS: The genetic distinctiveness of Yemenite Jews may explain their unusually high incidence of type 1 diabetes in Israel. Despite the presence of highly susceptible diabetogenic HL4 class II genes in this community, early exposure to cow's milk did not cause phenotypic expression of diabetes in Yemen. This finding suggests that in this population, either cow's milk does not play a crucial role in triggering diabetes, or environmentally conferred protection, such as frequent infectious disease in Yemen, was dominant.

Adult↗
PubMed2001

Predictors for benign solitary pulmonary nodule in tuberculosis-endemic area.

BACKGROUND: Solitary pulmonary nodule (SPN) may show different presentation in tuberculosis (TB)-endemic countries. The aim of this study was to identify clinical and radiological predictors favoring benign or malignant SPN in TB-endemic region. METHODS: Two hundred one SPNs in 201 consecutive Korean patients were included (< 3 cm in diameter, all confirmed by pathology or bacteriology, 93 benign and 108 malignant diseases). For clinical parameters, age, sex, smoking status and amount, and past history of pulmonary tuberculosis and diabetes mellitus were investigated retrospectively. For radiological parameters, size, location, margin characteristics, presence of calcification, pleural tag, surrounding satellite nodule, cavitation, internal low attenuation, open bronchus sign, surrounding ground-glass opacity, enhancement pattern of the SPNs and mediastinal lymph node (LN) enlargement were analyzed on chest CT scans. RESULTS: Patients with a older age (60.7 +/- 9.6 vs 56.2 +/- 13.1, p = 0.008) and more than 40-pack years smoking (27.8% vs 14.0%, p = 0.017) were more frequently related with malignant than benign SPN. On chest CT scans, spiculated margin, contrast enhancement more than 20 Hounsfield unit and presence of pleural tag and mediastinal LN enlargement were more frequently observed in malignant than benign SPNs. In contrast to previous studies, satellite lesions (21.5% vs 1.9%, p < 0.001) and cavitation (20.4% vs 5.6%, p = 0.001) were more frequently seen in benign than malignant SPN. Positive predictive values of benignity were 90.9% and 76.0%, respectively, when satellite lesions and cavitation were found in cases of SPN. CONCLUSION: Satellite lesions and cavitation on chest CT scan could be useful predictors for benign SPN in TB-endemic areas.

Adult↗