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Biomedical subjects

J N Lee

Publications and source records attributed to J N Lee.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of non-tuberculous mycobacteria in a hospital environment.

In recent years, non-tuberculous mycobacteria (NTM) have emerged as an important cause of opportunistic nosocomial infections but there is little known about the isolation and identification of NTM in Korea. The aim of this study was to assess the prevalence of NTM in the hospital environment and identify the species. A total of 150 samples were collected from different parts of the hospital. NTM were isolated and identified by restriction fragment length polymorphism analysis of the gene encoding rpoB and partial sequencing analysis of hsp65 and rpoB. In this study, 60 strains of NTM were isolated from 50 of the 150 samples. Half of the tap water samples (50 of 100) were positive for mycobacteria. An estimated 73.3% of the isolates were saprophytic, 21.7% were potentially pathogenic and 5% were unidentified. The presence of NTM in hospital tap water is not uncommon. Such water isolates might cause true nosocomial infection in immunocompromised patients, in addition to the risk of false-positive culture results.

Bacterial Proteins↗
PubMed2006

CYP17, CYP1A1 and COMT polymorphisms and the risk of adenomyosis and endometriosis in Taiwanese women.

BACKGROUND: The aim of the study was to test whether the COMT, CYP1A1 and CYP17 genes influence the risk of developing adenomyosis and endometriosis. METHODS: We conducted two case-control studies, where the cases (n = 198) had either of the two diseases, and controls (n = 312) were disease-free women. For the COMT gene, we selected the G/A nonsynonymous single-nucleotide polymorphism (SNP) that leads to valine-to-methionine (Val/Met) substitution. For the CYP1A1 gene, we used a functional T/C SNP in the 3'-noncoding region, and we genotyped a T/C functional SNP in the 5' region of the CYP17 gene for the present study. Hardy-Weinberg equilibrium was checked in both cases and controls. Logistic regression models were used to evaluate the genetic effect, with adjustment for other covariates. RESULTS: We found that the homozygous COMT genotype that encodes low enzyme activity had an increased risk for adenomyosis with an age-adjusted odds ratio of 3.2 (95% confidence interval 1.3-7.8; P = 0.006). The COMT gene, however, was not associated with endometriosis. Neither the CYP1A1 nor CYP17 genes had any significant association with either of the two diseases. CONCLUSION: The COMT gene significantly influences the risk of adenomyosis but not endometriosis. The present study does not provide evidence to support any of the three genes exerting pleiotropic effects on both diseases.

Adult↗
PubMed2004

Comparison of survival probabilities for living-unrelated versus cadaveric renal transplant recipients.

UNLABELLED: Any attempt to improve organ donation would be of benefit due to the growing shortage of cadaveric sources for transplantation. OBJECTIVE: We compared the graft survivals and possible predictive variables among renal transplant recipients with organs from living unrelated (LURD) versus cadaveric donors (CD). METHOD: Among 104 consecutive renal transplants performed from July 1992 to February 2003, 41 were from LURD and 24 from CD. Immunosuppressive regimens were based on cyclosporine and steroids with mycophenolate mofetil added after 1998. Patient and graft survivals were estimated using the Kaplan-Meier method and compared using log-rank tests. The significance level of predictive variables was analyzed with the Cox proportional hazard model. The follow-up period was 2 to 127 months (median 46 months). RESULTS: Eight recipients lost their grafts (six from LURD and two from CD) due to four chronic rejections, one acute rejection, one recurrence of primary disease, and one death with a functioning graft. The graft survival rates at 1, 3, 5, and 7 years were 97.6%, 91.9%, 88.5%, and 82.2% for LURD transplants versus 95.5%, 90.9%, 90.9%, and 90.9% for CD transplants, respectively (P > .05). Delayed graft function and donor age (>55 years old) were statistically significant predictors of graft survival among LURD transplants. Donor age (>55 years old) and multiple preoperative transfusion history were significant in CD transplants. CONCLUSION: LURD transplant survival was similar to that of CD transplants in our series. LURDs are an excellent source of organs to expand the donor pool.

Actuarial Analysis↗
PubMed2004

Risk factors on graft survival of living donor kidney transplantation.

UNLABELLED: Living donors have always been the basic resources of transplantation in our country, where cadaveric harvesting is still hampered for various reasons. OBJECTIVE: The aim of this study was to compare graft survival rates between living unrelated donor (LURD) and living related donor (LRD), to assess the potential risk factors for the graft survival, and to discuss the role of LURD. METHOD: From October 1991 to February 2003, 77 living donor renal transplants were performed: 41 were LURD and 36 were LRD transplants. The analyzed variables were donor relationship, recipient age and sex, donor age and sex, HLA-DR mismatching, nonspecific blood transfusion history of donor, acute rejection episodes, repeated rejection episode (more than 3 times), delayed graft function, recurred primary disease, and immunosuppressive regimen. Graft survival rate was assessed with the Kaplan-Meier method and the significance of possible variables with the Cox proportional hazard model. RESULTS: Eleven recipients lost their grafts (6 from LURD and 5 from LRD), most of them are due to chronic rejection (n = 7). Overall 3-, 5- and 10-year graft survival in live donors were 92.8%, 86.6%, and 76.9%, respectively. Graft survival at 3, 5, and 10 years being 91.9%, 88.5%, and 74.7% for the LURD versus 94%, 84%, and 78.8% for LRD transplants (P > .05). Acute rejection episodes, especially more than 3 times (risk ratio [RR] = 11.1) and preoperative multiple transfusion history (RR = 4.2) were significant factors on graft survival in our series. CONCLUSION: Acute rejection episodes markedly decreased the long-term graft survival in live donor renal transplants. The use of LURD transplants provides graft survival comparable with LRD transplants and proper management to acute rejection is essential for long-term graft survival.

Adult↗
PubMed2002

Effect of hormone replacement therapy on uterine fibroids in postmenopausal women--a 3-year study.

OBJECTIVE: The aim of this prospective 3-year clinical study was to examine the effect of hormone replacement therapy (HRT) on uterine fibroid growth among postmenopausal women. METHODS: Thirty-seven postmenopausal women with uterine solitary fibroids were recruited randomly for HRT in a 3-year program. All participants received 0.625 mg conjugated equine estrogen (CEE) and 5 mg medroxyprogesterone (MPA) daily. Fibroid volume was measured by transvaginal ultrasonography at baseline and then at 12-month intervals for 3 times. Clinically, significant fibroid growth was defined as an increase in volume of more than 25% compared with baseline. Also, 35 postmenopausal women with uterine fibroid were studied as control who did not receive HRT during the study period. RESULTS: Fibroid volume had increased significantly after 1 year both in HRT users and non-users. These increases continued to the second year significantly in HRT users but not in non-users. However, the volumes declined significantly at the third year to similar levels as those measured at baseline in control. In HRT users, fibroid volume though significantly increased at the third year (vs. baseline) but declined insignificantly in comparison with the second year. Clinically, at end of the third year study, one of 34 and three of 34 women increased fibroid volume over 25% compared with baseline in HRT non-users and users, respectively. CONCLUSIONS: HRT does increase uterine fibroid volume statistically. However, its effect appears in the first 2 years of use. The increased fibroid volume begins to decline at the third year both in HRT users and non-users. Clinically, the increased effect of HRT on uterine fibroid of postmenopausal women should be not over-emphasized at least for 3 years of usage.

Adult↗
PubMed2001

Akt activation by estrogen in estrogen receptor-negative breast cancer cells.

It has been a common belief that estrogen regulates cellular responses through binding to its receptor, the estrogen receptor (ER). In the nucleus, estrogen modulates the expression of estrogen-responsive genes through the action of the ER at the transcriptional level. In the cytoplasm, the ER-dependent signaling pathway has been shown to be involved in the activation of Akt and the downstream molecules. It is not clear, however, whether estrogen can modulate cytoplasmic signaling in an ER-independent manner. Human breast cancer cell lines without detectable ERs such as MDA-MB-435 and MDA-MB-231 were treated in estrogen-depleted medium followed by a brief treatment with estrogen. The activation of Akt was evaluated by a phosphoserine antibody. Our results showed that estrogen stimulated Akt activation, as indicated by phosphorylation at Ser(473) of the oncoprotein, in ER-negative breast cancer cells. Activation of Akt by estrogen in these cells was time and dose dependent and could be blocked by inhibitors of phosphatidylinositol 3'-kinase and Src kinase but not by estrogen antagonists. Our results provide evidence as well as the mechanism of the receptor-independent function of estrogen, in which the antiapoptotic factor Akt is activated.

Breast Neoplasms↗
PubMed2001

Quality of life issues in motor neurone disease: the development and validation of a coping strategies questionnaire, the MND Coping Scale.

A person's ability to cope with having motor neurone disease may be an important factor in determining their quality of life. We have developed a scale to measure coping strategies in people with MND. A disease-specific and patient-focused approach was employed. Open-ended interviews were used to generate initial items. Coping with the condition was an important consideration for all subjects. The final scale was administered to a sample of 44 people with MND. A factor analysis of the results demonstrated subscales comprised of distinct styles of coping. Reliability and validity were demonstrated within individual subscales. Significant correlations were shown between coping styles and psychological well being, disease duration and disability. Although still at a preliminary stage of development, the MND Coping Scale is proposed as a useful tool for further longitudinal study of coping in MND, with the potential to discover cause effect relationships between coping and psychological outcome.

Adaptation, Psychological↗
PubMed2001

Cholesterol biosynthesis from lanosterol. A concerted role for Sp1 and NF-Y-binding sites for sterol-mediated regulation of rat 7-dehydrocholesterol reductase gene expression.

The 7-dehydrocholesterol reductase (Dhcr7) is the terminal enzyme in the pathway of cholesterol biosynthesis. We have previously reported that sterol depletion in vivo caused a significant induction of both liver mRNA and enzyme activity of Dhcr7 (Bae, S.-H., Lee, J. N., Fitzky, B. U., Seong, J., and Paik, Y.-K. (1999) J. Biol. Chem. 274, 14624-14631). In this paper, we also observed liver cell-specific sterol-mediated Dhcr7 gene induction in vitro by sterol depletion in rat hepatoma cells, suggesting the presence of sterol-mediated regulatory elements in the Dhcr7 gene. To understand the mechanisms responsible for regulating Dhcr7 expression, we have isolated the 5'-flanking region of the gene encoding rat Dhcr7 and have characterized the potential regulatory elements of the gene that are responsible for sterol-mediated regulation. The Dhcr7 promoter contains binding sites for Sp1 (at -177, -172, -125, and -20), NF-Y (at -88 and -51), and SREBP-1 or ADD1 (at -33). Deletion analysis of the Dhcr7 gene promoter (-1053/+31), employing a nested series of Dhcr7-luciferase constructs, demonstrated that the -179 upstream region of the gene is necessary and sufficient for optimal efficient sterol-regulated transcription. DNase I footprinting and electrophoretic mobility shift assay showed that the SRE1/E box (-33/-22) involved in sterol response of many sterol-related enzyme genes was protected specifically by the overexpressed recombinant ADD1. Mutational analysis for the functional relationship between the identified cis-elements in this region indicate that one of the binding sites for Sp1 (GC box at -125) and NF-Y (CCAAT box at -88) plays a cooperative role in the sterol-mediated activation, in which the latter site also acts as a co-regulator for SREBP-activated Dhcr7 promoter activity. We believe that Dhcr7 is the first enzyme characterized with a sterol-regulatory function in the post-lanosterol pathway. This may be important for understanding the coordinated control of cholesterol biosynthesis as well as the molecular mechanism of Smith-Lemli-Opitz syndrome-related protein in mammals.

Animals↗
PubMed2001

web-based interactive data processing: application to stable isotope metrology.

To address a fundamental need in stable isotope metrology, the National Institute of Standards and Technology (NIST) has established a web-based interactive data-processing system accessible through a common gateway interface (CGI) program on the internet site http://www. nist.gov/widps-co2. This is the first application of a web-based tool that improves the measurement traceability afforded by a series of NIST standard materials. Specifically, this tool promotes the proper usage of isotope reference materials (RMs) and improves the quality of reported data from extensive measurement networks. Through the International Atomic Energy Agency (IAEA), we have defined standard procedures for stable isotope measurement and data-processing, and have determined and applied consistent reference values for selected NIST and IAEA isotope RMs. Measurement data of samples and RMs are entered into specified fields on the web-based form. These data are submitted through the CGI program on a NIST Web server, where appropriate calculations are performed and results returned to the client. Several international laboratories have independently verified the accuracy of the procedures and algorithm for measurements of naturally occurring carbon-13 and oxygen-18 abundances and slightly enriched compositions up to approximately 150% relative to natural abundances. To conserve the use of the NIST RMs, users may determine value assignments for a secondary standard to be used in routine analysis. Users may also wish to validate proprietary algorithms embedded in their laboratory instrumentation, or specify the values of fundamental variables that are usually fixed in reduction algorithms to see the effect on the calculations. The results returned from the web-based tool are limited in quality only by the measurements themselves, and further value may be realized through the normalization function. When combined with stringent measurement protocols, two- to threefold improvements have been realized in the reproducibility of carbon-13 and oxygen-18 determinations across laboratories.

Journal Article↗
PubMed2001

Practical application of fMRI for surgical planning.

We report our experience evaluating tasks designed to visualize regions of motor and language brain activation using functional magnetic resonant imaging (fMRI). Our goal was to identify a battery of tasks which would provide a range of brain imaging studies which could be used clinically for surgical planning, with the requirement that they could be performed and analyzed rapidly, thus, cost effectively. These tasks were chosen to assess (1) motor control of the hands, fingers, and feet, and (2) language processing using both auditory and visual task presentations. From January through April 2001, five patients and eight normal subjects were studied. A selection of three or four tasks acquired with an EPI sequence coupled with a high resolution 3D MR sequence were completed in 45- 60 min of scanner time. Identification of the location of eloquent cortex serving aspects of motor and language functions was successful in four of the five patients and all of the eight normal subjects.

Brain Mapping↗
PubMed2001

Purification of soluble beta-glucan with immune-enhancing activity from the cell wall of yeast.

Beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions, especially by activating macrophages. However, a major obstacle to the clinical application of beta-(1-->3)-glucan is its low solubility in aqueous media. In this study, soluble beta-glucan, free of mannoprotein, was prepared, and its effects on TNF-alpha secretion and phagocytosis by macrophages were evaluated. Beta-glucan was first rendered soluble from the yeast cell wall by alkaline extraction (glucan-p1). The extract contained 2.8% of protein which was subsequently removed by successive DEAE-cellulose and ConA chromatography. Beta-glucan thus prepared was completely free of mannoprotein and was soluble at neutral pH (glucan-p3). The effects of beta-glucan on phagocytosis and TNF-alpha release activity were investigated. While glucan-p1 moderately induced TNF-alpha secretion at 200 microg/ml (550 pg of TNF-alpha/5 x 10(5) cells), glucan-p3 markedly stimulated macrophages at 200 microg/ml (2,860 pg of TNF-alpha/5 x 10(5) cells). Furthermore, glucan-p3 stimulated phagocytosis about 20% more than glucan-p1 did. In conclusion, we purified water-soluble beta-glucan which was completely devoid of mannoprotein and effectively stimulated the macrophage function, enabling it to be used as an intravenous injection for sepsis.

Adjuvants, Immunologic↗
PubMed2001

Pseudo-Meigs syndrome and elevated levels of tumor markers associated with benign ovarian tumors--two case reports.

Elevated tumor markers for a post-menopausal woman presenting with a multilocular adnexal mass, ascites, and pleural effusion were interpreted as being highly suspicious of malignancy. This paper describes two cases of ovarian tumors presenting with all signs of malignancy. Following surgical excision of the masses, and histopathological assay, a benign pure struma ovarii and a mucinous cystadenoma were diagnosed by pathologists. The immediate and complete resolution of symptoms were achieved post-operatively, and the previously-evident abnormal tumor markers rapidly declined to the normal range, the two tumors were subsequently classified as pseudo-Meigs' syndromes.

Aged↗
PubMed2000

Protective mechanism of glucose against alloxan-induced beta-cell damage: pivotal role of ATP.

Glucose prevents the development of diabetes induced by alloxan. In the present study, the protective mechanism of glucose against alloxan-induced beta-cell damage was investigated using HIT-T 15 cell, a Syrian hamster transformed beta-cell line. Alloxan caused beta-cell damages with DNA fragmentation, inhibition of glucose-stimulated insulin release, and decrease of cellular ATP level, but all of these beta-cell damages by alloxan were prevented by the presence of 20 mM glucose. Oligomycin, a specific inhibitor of ATP synthase, completely abolished the protective effects of glucose against alloxan-induced cell damage. Furthermore, treatment of nuclei isolated from HIT-T15 cells with ATP significantly prevented the DNA fragmentation induced by Ca2+. The results indicate that ATP produced during glucose metabolism plays a pivotal role in the protection of glucose against alloxan-induced beta-cell damage.

Adenosine Triphosphate↗
PubMed2000

Light chain of natural antibody plays a dominant role in protein antigen binding.

Examinations of the contribution and the specificity of heavy (H) and light (L) chains of natural antibodies to antigen binding may help us to better understand antigen recognition and the development of naive B cells. We previously generated natural Fab antibody fragments reactive to preS1 of HBV using a naive, non-immunized Fab antibody library derived from peripheral B cells of a normal healthy volunteer. We now constructed expression vectors for the Fd (VH + CH1), L chain, and scFv fragments using the sequences encoding parental Fabs as a source of natural antibody genes. The recombinant antibody fragments were expressed as inclusion bodies in E. coli BL21 (DE) cells. When denatured and then refolded, the antibody fragments retained their binding properties. Recombinant L chains and scFvs exhibited three- to 40-fold higher affinities (in the order of 10(7) M(-1)) over the parental Fabs, whereas the affinities of Fds (in the order of 10(5) M(-1)) were much lower compared to the parental Fabs. The results obtained from sandwich ELISA revealed that the L chains bound the virus more efficiently than Fds. Additional experiments were performed to evaluate the specificity of the recombinant fragments for surface proteins of HBV. Fds and L chains were reactive towards HBsAg and the preS2 peptide as well as preS1 and showed patterns of epitope recognition quite different from those of parental Fabs. The data presented here demonstrate that the prominence of the L chain in determining protein binding activity is a property of natural antibodies and is quite unlike the antibodies induced by immunization, and that the specificity of Fab is not determined by the individual antibody chain but by the correct pairing of H and L chain.

Antibody Affinity↗
PubMed2000

Intensity correction by subtraction for phased-array MRA images.

A method of intensity correction is described that is particularly useful for magnetic resonance angiography images acquired with phased-array coils. In this method a low-pass filtered version of the image is subtracted from the original image to remove signal variations due to the phased-array coil. This avoids the noise amplification caused by division correction and enhances the signal-to-noise ratio of small arteries in maximum intensity projections. J. Magn. Reson. Imaging 2000;12:501-504.

Cerebellum↗