Biomedical subjects

Hanjong Ahn

Publications and source records attributed to Hanjong Ahn.

13 recordsLinked to original sources

PubMed2006

Renal angiomyolipoma with minimal fat: differentiation from other neoplasms at double-echo chemical shift FLASH MR imaging.

PURPOSE: To prospectively evaluate the diagnostic performance of double-echo gradient-echo (GRE) chemical shift magnetic resonance (MR) imaging in the differentiation of angiomyolipoma (AML) with minimal fat from other renal neoplasms, with pathologic examination or follow-up data serving as the reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Double-echo GRE chemical shift MR imaging was performed in 55 patients (29 men and 26 women; mean age, 49 years +/- 14 [standard deviation]) with 55 renal tumors, including 37 (67%) pathologically proved tumors (23 renal cell carcinomas, nine AMLs, two oncocytomas, two lymphomas, and one reninoma) and 18 (33%) clinically diagnosed tumors (17 AMLs and one indeterminate malignancy). All tumors showed no intratumoral fat and had homogeneous enhancement and a prolonged or gradual enhancement pattern on biphasic helical computed tomographic scans. Signal intensity was measured in the renal tumor and spleen on in-phase and opposed-phase images. The signal intensity index and tumor-to-spleen ratio in AMLs and non-AMLs were calculated and compared with the Student t test. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic accuracy of the signal intensity index and tumor-to-spleen ratio and to extract the optimal cut-off values in the differentiation of AMLs and non-AMLs. RESULTS: The signal intensity index and tumor-to-spleen ratio were different between AMLs (42% +/- 11 and -43% +/- 17, respectively) and non-AMLs (5% +/- 14 and -4% +/- 16, respectively) (P < .001). The area under the ROC curve was 0.975 for the signal intensity index and 0.952 for the tumor-to-spleen ratio. For differentiation of AMLs from non-AMLs, sensitivity and specificity were (a) 96% and 93%, respectively, with a signal intensity index of 25% and (b) 88% and 97%, respectively, with a tumor-to-spleen ratio of -32%. CONCLUSION: Double-echo GRE chemical shift MR imaging can be used to differentiate AML with minimal fat from other renal neoplasms.

Adult↗

PubMed2006

Prostate cancer in Korean men exhibits poor differentiation and is adversely related to prognosis after radical prostatectomy.

OBJECTIVES: To investigate the clinical and pathologic characteristics of prostate cancer in Korean men to determine how ethnic differences affect clinical outcome. METHODS: The clinical and pathologic data of 604 Korean men who underwent radical prostatectomy from 1994 to 2003 were reviewed. Biochemical failure was defined as a prostate-specific antigen (PSA) level of 0.2 ng/mL or greater on two consecutive occasions after having achieved an undetectable PSA level. Patient distribution with respect to the clinical and pathologic parameters and biochemical failure rates were compared with those of contemporary Western series. RESULTS: The mean preoperative PSA level was 9.9 ng/mL (range 0.4 to 38.8) and the median biopsy Gleason score was 7. The Gleason score was 7 in 186 patients (30.8%) and greater than 7 in 169 (28.0%). Gleason scores stratified with respect to clinical stage and PSA range revealed the proportion of patients with high Gleason scores (7 or greater) to be more than 50% of each subgroup throughout the clinical stages and PSA ranges. At a median follow-up of 57.9 months (range 22 to 131), biochemical failure occurred in 24.2% of all patients and in 14.3% of those with an initial serum PSA level of 10.0 ng/mL or lower. On multivariate Cox regression analysis, the Gleason score showed the strongest statistical significance for biochemical failure (P = 0.001, hazard ratio 1.376, 95% confidence interval 1.056 to 1.792) for patients with a serum PSA level of 10.0 ng/mL or lower. CONCLUSIONS: A significant proportion of prostate cancers arising in Korean men exhibit poor differentiation, regardless of the initial serum PSA level or clinical stage at presentation, and adversely affect prognosis, causing a greater rate of PSA failure.

Adult↗

PubMed2006

Changes in the upper urinary tract after radical cystectomy and urinary diversion: a comparison of antirefluxing and refluxing orthotopic bladder substitutes and the ileal conduit.

PURPOSE: We evaluated and compared the effects of different types of urinary diversion on functional and radiographic changes in the upper urinary tract. MATERIALS AND METHODS: We analyzed data on 275 patients who underwent radical cystectomy and urinary diversion for bladder cancer and were observed at least 12 months. Of the patients 197 received an orthotopic bladder substitute, including antirefluxing ureteral anastomoses in 111 (group 1) and refluxing ureteral anastomoses in 86 (group 2). Ileal conduits were created in 78 patients (group 3). Serial serum Cr, radiographic changes in the upper urinary tract after diversion and the number of episodes of APN were compared by diversion method. Mean followup was 52 months (range 12 to 174 months) with no difference among the groups. RESULTS: Compared with group 3 patients in groups 1 and 2 demonstrated a significantly higher incidence of moderate to severe hydronephrosis (p = 0.001) but the incidence was similar between groups 1 and 2 (6.3%, 8.3% and 1.4% of the renal units in groups 1 to 3, respectively). Stabilized postoperative Cr did not differ among the groups. CRF, defined as Cr 3.0 mg/dl or greater, occurred in 2.7% of the patients in group 1 and in 3.5% of those in group 2 but in none in group 3. APN was noted in 3.3%, 4.4% and 0.4% of patients in groups 1 to 3, respectively (p = 0.012). CONCLUSIONS: An ileal conduit with a lower rate of diversion related hydronephrosis, CRF and morbidity associated with APN was superior to orthotopic bladder substitutes. Between the refluxing and antirefluxing types of orthotopic bladder substitutes no significant difference in functional or radiographic changes was noted.

Adult↗

PubMed2006

Effectiveness of local anaesthesia techniques in patients undergoing transrectal ultrasound-guided prostate biopsy: a prospective randomized study.

AIM: This study was designed to compare the effectiveness of intrarectal lidocaine gel versus periprostatic lidocaine injection during transrectal ultrasound (TRUS)-guided prostate biopsy. METHODS: Ninety men undergoing transrectal prostate biopsy from July through December 2004 were randomized into three groups of 30 patients each. Before the biopsy, patients in Group 1 received 20 mL of 2% lidocaine gel intrarectally; patients in Group 2 received 5 mL (2.5 mL per side) of 2% lidocaine solution injected near the junction of the seminal vesicle with the base of the prostate (along the neurovascular bundles), and patients in Group 3 (control group) received 5 mL (2.5 mL per side) of normal saline injected along the neurovascular bundles. Pain level after the biopsy was assessed using a 10-point linear visual analog scale (VAS). Results were statistically compared by the Wilcoxon Rank Sum test. RESULTS: Patients in Group 2 had significantly lower VAS scores than those in Group 3 (3.6 +/- 2.1 vs 5.8 +/- 1.9, P < 0.0001), but those in Group 1 did not (5.5 +/- 2.7 vs 5.8 +/- 1.9, P = 0.67). Gross hematuria, rectal bleeding, and hemospermia occurred in 36 (40.0%), 6 (7%) and 5 (6%) patients. One patient had temporary vasovagal syncope. No patient reported febrile urinary tract infection or urinary retention. CONCLUSIONS: Periprostatic injection of local anaesthetic is a safe technique that significantly reduces pain during prostate biopsy, whereas intrarectal lidocaine injection did not reduce pain. This safe, simple technique should be applied in men undergoing TRUS-guided prostate biopsy to limit patient discomfort.

Adult↗

PubMed2005

STAT1-independent down-regulation of interferon-gamma-induced class II transactivator and HLA-DR expression by transforming growth factor beta-1 in human glomerular endothelial cells.

BACKGROUND: The competition between STAT1 and Smad3 for a limiting amount of the nuclear protein p300, a transcriptional coactivator, was suggested to be a mechanism for the antagonism between interferon-gamma (IFN-gamma) and transforming growth factor-beta1 (TGF-beta1). We investigated the effect of TGF-beta1 on IFN-gamma-induced HLA-DR production in cultured human glomerular endothelial cells (HGECs), and the involvement of p300 in this process. METHODS: Cell surface expression of HLA-DR and mRNA levels of HLA-DR and class II transactivator (CIITA), the master regulator of HLA-DR gene transcription, were measured by cellular ELISA and Northern blot, respectively. The levels of STAT1 and Smad3 protein were analyzed by Western blot. Nuclear binding activity of STAT1 was assessed by electrophoretic mobility shift assay. RESULTS: IFN-gamma increased the cell surface expression of HLA-DR along with increases in the mRNA levels of CIITA and HLA-DR, while these stimulatory effects of IFN-gamma were down-regulated by TGF-beta1. IFN-gamma increased phosphorylation of STAT1 and this activation was not inhibited by TGF-beta1. IFN-gamma increased binding of p-STAT1 to p300, while TGF-beta1 increased binding of Smad3 to p300. TGF-beta1-induced Smad3 binding to p300 was inhibited by IFN-gamma, whereas IFN-gamma-induced p-STAT1 binding to p300 was not inhibited by TGF-beta1. IFN-gamma increased DNA binding activity of STAT1. Inhibition of interaction between STAT1 and p300 by addition of anti-p300 antibody to nuclear extract down-regulated DNA binding activity of STAT1. In contrast, TGF-beta1 did not inhibit IFN-gamma-induced STAT1 binding to DNA. CONCLUSIONS: TGF-beta1 down-regulated IFN-gamma-induced CIITA and HLA-DR expression in HGECs. Though there was an antagonism between IFN-gamma and TGF-beta1, the competition for p300 between p-STAT1 and Smad3 was not the mechanism for it.

Blotting, Northern↗

PubMed2005

Wash-in rate on the basis of dynamic contrast-enhanced MRI: usefulness for prostate cancer detection and localization.

PURPOSE: To evaluate the usefulness of the wash-in rate based on dynamic contrast-enhanced (DCE) MRI for the detection and localization of prostate cancer. MATERIALS AND METHODS: In 53 patients, the wash-in rate was measured in the cancer area and in three normal areas (the peripheral zone, inner portion of the transitional zone, and outer portion of the transitional zone). On the basis of these data, parametric imaging was generated and then its accuracy for cancer detection and location was evaluated compared to that of T2-weighted imaging without the use of an endorectal coil. For that purpose the entire prostate was divided into 18 segments. RESULTS: The wash-in rate value was greater in cancer tissue (9.2/second) than in three normal tissues (3.3/second, 6.7/second, and 3.2/second, respectively; P<0.001). The sensitivity and specificity were greater on parametric imaging of the wash-in rate compared to T2-weighted imaging in the entire prostate (96% and 82% vs. 65% and 60%, respectively) and the peripheral zone (96% and 97% vs. 75% and 53%; P<0.05). In the transitional zone, the sensitivity was greater on parametric imaging (96%) than on T2-weighted imaging (45%; P=0.016), but the specificity was similar (51% vs. 73%; P=0.102). CONCLUSION: The wash-in rate based on DCE-MRI is a useful parameter for prostate cancer detection and localization.

Aged↗

PubMed2005

TuJ1 (class III beta-tubulin) expression suggests dynamic redistribution of follicular dendritic cells in lymphoid tissue.

Follicular dendritic cells (FDCs) play central roles in the B cell survival, proliferation, and differentiation into memory cells. Here, we show that TuJ1 (class III beta-tubulin) is expressed strongly in FDCs of human lymphoid tissue. TuJ1 has been a marker of neurons in the central and peripheral nervous systems from the early stage of neural differentiation. FDCs expressed TuJ1 protein diffusely in both light and dark zones of germinal centers in all human lymphoid tissues. In contrast, CD21 expression was relatively concentrated to the light zone, suggesting that TuJ1 was a marker for FDCs with broader spectrum than CD21. In addition to the germinal center, there were single TuJ1-expressing cells scattered in the mantle zone, blurring the border of the FDC network. In human tonsils, single scattered TuJ1-positive cells were also present in the crypt epithelium, suggesting a dynamic redistribution of FDCs among the antigen-rich epithelium, mantle zone, and germinal center. Such migration of FDCs could reflect a way of direct transport of various antigens carried on their surface to the germinal center, and a basis for the polarity of lymphoid follicles toward the epithelium in mucosa-associated lymphoid tissues. HK cells, cultured FDCs, also expressed TuJ1. The expression of TuJ1 by FDCs suggests that they may share certain biological characteristics of the neural system.

Blotting, Western↗

PubMed2005

Prognostic value of lymphovascular invasion in transitional cell carcinoma of upper urinary tract.

OBJECTIVES: To elucidate the prognostic significance of lymphovascular invasion (LVI) in patients with upper tract transitional cell carcinoma. METHODS: Of 86 patients with upper tract transitional cell carcinoma who underwent nephroureterectomy with bladder cuff (95%) or parenchymal-sparing (5%) surgery from 1991 to 2002, and who met our inclusion criteria, the data of 73 were available for pathologic review of LVI. The mean patient age was 59.1 years, and the median follow-up was 42.3 months. Using univariate and multivariate analyses, we determined the influence of multiple prognostic factors, including age, sex, tumor stage (T or N), tumor grade, and LVI, on the 5-year disease-specific and recurrence (local recurrence or distant metastasis)-free survival rates. We generated 5-year disease-specific and recurrence-free survival curves in terms of LVI in patients without lymph node involvement. RESULTS: The overall 5-year disease-specific and recurrence-free survival rate was 88% and 75%, respectively (n = 73). In univariate analysis, T stage, grade, and LVI significantly affected both survival rates. N stage was significant for 5-year recurrence-free survival. In multivariate analysis, LVI was the only significant predictor of recurrence-free survival, and no factor was significant for disease-specific survival. Of 10 patients with positive lymph nodes, 7 had LVI. In patients without lymph node involvement or Stage T4 disease (Ta-T3N0M0, n = 62), the 5-year disease-specific and recurrence-free survival rate was 98% and 94%, respectively, in the absence of LVI and 70% and 60%, respectively, in the presence of LVI (P = 0.0005 and P = 0.0007, respectively). CONCLUSIONS: LVI is an independent prognostic factor for recurrence-free survival in transitional cell carcinoma of the upper urinary tract. Because LVI is strongly associated with a poorer prognosis, systemic adjuvant therapy should be considered in the presence of LVI, even if the lymph nodes are not involved.

Carcinoma, Transitional Cell↗

PubMed2005

Nomograms for the prediction of pathologic stage of clinically localized prostate cancer in Korean men.

We analyzed the prostate cancer data of 317 Korean men with clinically localized prostate cancer who underwent radical prostatectomy at Asan Medical Center between June 1990 and November 2003 to construct nomograms predicting the pathologic stage of these tumors, and compared the outcome with preexisting nomograms. Multinomial log-linear regression was performed for the simultaneous prediction of organ-confined disease (OCD), extracapsular extension (ECE), seminal vesicle invasion (SVI) and lymph node metastasis (LNM) using serum prostate-specific antigen (PSA), Gleason score and clinical stage. Nomograms representing percent probabilities were constructed and compared with those presented by Partin et al. by calculating areas under the receiver operating characteristics (ROC) curves. Median serum PSA at surgery was 10.8 ng/mL, and median biopsy Gleason score was 7. Overall OCD, ECE, SVI and LNM rates were 59.6%, 20.5%, 11.7% and 8.2%, respectively, and areas under the curves were 0.724, 0.626, 0.662, and 0.794, respectively. Pathologic stage of localized prostate cancer in Korean men may be predicted using the Partin table, with acceptable accuracy for OCD and LNM, but less so for ECE and SVI.

Adult↗

PubMed2004

Dexamethasone regulates AP-1 to repress TNF-alpha induced MCP-1 production in human glomerular endothelial cells.

BACKGROUND: Glomerular endothelial cells play a role in the pathogenesis of glomerulonephritis by producing chemotactic factors. We investigated the role of NF-kappa B and AP-1 in tumour necrosis factor alpha (TNF-alpha) induced monocyte chemoattractant protein 1 (MCP-1) production in cultured human glomerular endothelial cells (HGEC). We also examined whether or not these processes could be modified by glucocorticoid. METHODS: MCP-1 protein and mRNA levels were measured by ELISA and northern blot. NF-kappa B and AP-1 binding activity were assessed by electrophoretic mobility shift assay. Cytosolic I kappa B alpha and nuclear p65 protein were evaluated by western blot. For specific inhibition of NF-kappa B or AP-1, we used a decoy oligodeoxynucleotide. RESULTS: TNF-alpha (10 ng/ml) increased MCP-1 mRNA expression in HGEC and also the release of MCP-1 protein into culture media. These effects could be partially inhibited by dexamethasone (10 nM). TNF-alpha induced MCP-1 production appeared to be NF-kappa B and AP-1 interdependent, based on the following results. (i) TNF-alpha increased NF-kappa B and AP-1 binding activity. (ii) Both NF-kappa B decoy oligodeoxynucleotide and AP-1 decoy oligodeoxynucleotide partially suppressed TNF-alpha induced MCP-1 mRNA expression. On the other hand, dexamethasone decreased TNF-alpha induced DNA-binding activity of AP-1 without an effect on the DNA-binding activity of NF-kappa B, cytosolic I kappa B alpha degradation or p65 nuclear translocation. CONCLUSIONS: These data demonstrate that while TNF-alpha induced MCP-1 production is mediated by the cooperative action of NF-kappa B and AP-1 in HGEC, dexamethasone represses TNF-alpha induced MCP-1 production via suppression of AP-1 binding activity.

Base Sequence↗

PubMed2004

The impact of tumor location on prognosis of transitional cell carcinoma of the upper urinary tract.

PURPOSE: We assessed the impact of traditional prognostic factors and tumor location on the survival of patients treated for upper tract transitional cell carcinoma (TCC). MATERIALS AND METHODS: We retrospectively analyzed the data on 86 patients with upper tract TCC who underwent nephroureterectomy with a bladder cuff (95%) or parenchymal sparing surgery (5%). Mean patient age was 59.5 years and median followup was 43.8 months. The influence of traditional prognostic factors such as age, gender, tumor stage, grade and location on 5-year disease specific and recurrence-free (local recurrence or distant metastasis) survival rates was analyzed. The difference in survival rates between renal 45 pelvis and 41 ureteral cases was analyzed according to the respective T stage and grade. RESULTS: Overall 5-year disease specific and recurrence-free survival rates were 83% and 72%, respectively. The significant prognostic factors for survival rates by univariate analysis were T stage, grade and location. N stage was significant for 5-year recurrence-free survival. On multivariate analysis tumor location was the only independent prognostic factor for the 2 survival rates, while N stage was significant for 5-year recurrence-free survival. Patients with ureteral tumor had a worse prognosis than those with pelvis tumor at the same stage or grade (p = 0.036). CONCLUSIONS: Pelvis and ureteral TCC are not the same disease in terms of invasion and prognosis. Ureteral TCC is associated with a higher local or distant failure rate than renal pelvis TCC. A radical surgical approach including meticulous lymphadenectomy may be therapeutic in patients with invasive ureteral TCC.

Carcinoma, Transitional Cell↗

PubMed2004

Estrogen induction of smooth muscle differentiation of human prostatic stromal cells is mediated by transforming growth factor-beta.

PURPOSE: The differentiation of prostatic fibroblasts into smooth muscle cells is regarded as the key step in the development of periurethral stromal nodules. Intraprostatic stromal estrogen and transforming growth factor-beta1 (TGF-beta1) are considered to be involved in this process. We investigated whether estrogen enhances the stromal cell growth and induction of smooth muscle phenotype, and whether this process is mediated by TGF-beta1. MATERIALS AND METHODS: Prostate specimens obtained from patients undergoing transurethral resection of the prostate were used for primary cell culture. Growth of the prostatic stromal cells was assessed with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test and cell numbers were determined by hemocytometry. The effect of estradiol on the production of TGF-beta1 protein and expression of smooth muscle markers such as smooth muscle alpha-actin (SMA) and desmin were evaluated by Western blot and immunohistochemical staining. The mRNA levels of TGF-beta1 and its receptors were analyzed by reverse transcriptase-polymerase chain reaction. We also investigated whether the enhanced expression of SMA by estradiol was mediated through the TGF-beta1 pathway using TGF-beta1 blocking antibody. RESULTS: Estradiol promoted the proliferation of prostatic stromal cells by 10% to 20%. Estradiol and TGF-beta1 enhanced SMA expression. Although the levels of mRNA expression of TGF-beta1 or its receptors did not change after estradiol treatment, increased production of TGF-beta1 protein was noted. Enhanced expression of SMA by estradiol was blocked by TGF-beta1 blocking antibody. CONCLUSIONS: These results suggest that estrogen stimulates the growth of prostatic stromal cells and increases smooth muscle cell markers, which may be achieved through a pathway involving TGF-beta1.

Cell Differentiation↗

PubMed2002

Laparoscopic nephrectomy for tuberculous nonfunctioning kidney: comparison with laparoscopic simple nephrectomy for other diseases.

OBJECTIVES: To summarize the results of our 31 consecutive laparoscopic nephrectomies for renal tuberculosis and compare them with 45 laparoscopic nephrectomies performed for other benign etiologies. We previously reported our initial successful experiences in expanding the role of laparoscopic surgery with the introduction of laparoscopic nephrectomy for renal tuberculosis. METHODS: Thirty-one laparoscopic nephrectomies for renal tuberculosis were performed between June 1996 and December 2001. The patients consisted of 11 men and 20 women with a mean age of 44.2 years (range 29 to 64). The control group consisted of 17 men and 28 women with a mean age of 48.6 years (range 17 to 60). The two groups were comparable with regard to demographic data. Statistical analyses were used to compare the two groups in terms of various parameters, including surgical time, blood loss, analgesic requirements, resumption of oral intake, and hospital stay. RESULTS: Laparoscopic nephrectomy was successful in 30 cases of the tuberculosis group and 44 cases of the control group. The two groups showed comparable perioperative and postoperative parameters, except for mean operative time, which, at 244 minutes for the tuberculosis group, was significantly greater than the 216 minutes for the control group (P <0.05). No significant intraoperative or postoperative complications were observed in either group. CONCLUSIONS: The results of this study indicate that laparoscopic nephrectomy for renal tuberculosis is a safe, effective, and less invasive treatment modality. Therefore, we suggest that the renal tuberculous nonfunctioning kidney should be approached initially using the laparoscopic approach.

Adult↗