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Biomedical subjects

H Ahn

Publications and source records attributed to H Ahn.

At least 37 records · Page 2Linked to original sources
PubMed2000

TGF-beta(1) down-regulates inflammatory cytokine-induced VCAM-1 expression in cultured human glomerular endothelial cells.

BACKGROUND: Endothelial cells are active participants in the processes controlling coagulation, inflammation and the immune response. Variations are recognized between endothelia isolated from different vascular beds as well as from different species. Though transforming growth factor-beta(1) (TGF-beta(1)) has been known to have an anti-inflammatory action, little is known about its effect on expression of cellular adhesion molecules during the inflammatory process in human glomerular endothelial cells. The aim of this study was to determine the effect of TGF-beta(1) on the inflammatory cytokine-induced expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human glomerular endothelial cells. METHODS: The culture of human glomerular endothelial cells was established using the normal portion of nephrectomized renal tissues and identified by factor VIII staining and cellular uptake of fluorescent-labelled acetylated low-density lipoprotein (LDL). The endothelial cells were stimulated by interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) with or without TGF-beta(1). Cellular expression of VCAM-1 was measured by enzyme-linked immunosorbent assay (ELISA) and flow cytometry, and VCAM-1 mRNA was measured by Northern blot analysis. RESULTS: TGF-beta(1) (1, 10 and 25 ng/ml) blunted IL-1beta- (5 ng/ml) induced VCAM-1 expression significantly (OD=1.08+/-0.14, 1. 10+/-1.16 and 1.05+/-0.14 vs IL-1beta=1.97+/-0.29, n=6, P<0.05) in ELISA. The addition of TGF-beta(1) (1, 10 and 25 ng/ml) also suppressed TNF-alpha- (10 ng/ml) induced VCAM-1 expression (OD=1. 14+/-0.15, 1.17+/-0.17 and 1.18+/-0.16 vs TNF-alpha=1.96+/-0.26, n=6, P<0.05). The same results were obtained by flow cytometry. TGF-beta(1) (10 ng/ml) inhibited both IL-1beta- (5 ng/ml) and TNF-alpha-(10 ng/ml) induced expression of VCAM-1 (MFI: IL-1beta=90. 8+/- 17.6, IL-1beta+TGF-beta(1)=37.8+/-14.9, TNF-alpha=113.6+/- 12.4, TNF-alpha+TGF-beta(1)=64.3+/-13.8, mean+/-SD, n=3, P<0.05). By Northern blot analysis, TGF-beta(1) (10 ng/ml) significantly suppressed the stimulatory effect of IL-1beta and TNF-alpha. CONCLUSIONS: These results show that TGF-beta(1) down-regulates the inflammatory cytokine-induced expression of VCAM-1 in human glomerular endothelial cells, which could be a novel mechanism for the anti-inflammatory action of TGF-beta(1) during the inflammatory processes in human glomerular diseases.

Cells, Cultured↗
PubMed2000

Distribution of obstructive intimal lesions and their cellular phenotypes in chronic pulmonary hypertension. A morphometric and immunohistochemical study.

We investigated the distribution of pulmonary arteriopathy in chronic pulmonary hypertension (PH) in a quantitative histopathologic study, using computer-assisted image analysis. We also examined the histologic manifestations and cellular phenotypes of various obstructive intimal lesions in PH with an immunohistochemical method. A total of 53 lungs removed at autopsy or explantation were obtained for the study from 51 documented cases of moderate to severe PH (15 cases of primary pulmonary hypertension [PPH], eight cases of Eisenmenger's syndrome [EISEN], 22 cases of chronic major-vessel thromboembolic disease [CTED], and three cases of PH associated with other known causes), and two unused donor lungs served as normal controls. Intimal thickening in PPH was most prominent in small pulmonary arteries and arterioles less than 200 micrometer in diameter. Plexiform lesions in PPH were associated with significantly smaller arteries than in EISEN. Arteries larger than 400 micrometer showed a significant intimal thickening only in CTED. Obstructive intimal lesions in PH comprised a morphologic spectrum with frequent intermediate forms between plexiform and thrombotic lesions. Most cells within various intimal lesions showed an immunoprofile of myofibroblasts that were positive for vimentin and alpha-smooth muscle actin, but negative for desmin and endothelial markers including Factor VIII, clonal designator (CD)31, and CD34. Endothelial markers were positive only in the single layer of cells lining slitlike lumens, when the latter were present. In conclusion, major types of PH had characteristic distribution patterns of obstructive intimal lesions, showing mainly a myofibroblastic phenotype and variable endothelial/vascular differentiation.

Adult↗
PubMed2000

Polyacetylenes from angelica gigas and their inhibitory activity on nitric oxide synthesis in activated macrophages.

In activated macrophages the inducible form of nitric oxide synthase (i-NOS) generates high amounts of the toxic mediator, nitric oxide (NO) which contributes to the circulatory failure associated with septic shock. Two polyacetylenes were isolated from the medicinal plant Angelica gigas and their structures were elucidated as octadeca-1,9-dien-4,6-diyn-3,8,18-triol (1) and 18-acetoxy-octadeca-1,9-dien-4,6-diyn-3,8-diol (2) by spectroscopic method. These polyacetylenes and their peracetate, 3, 8, 18-triacetoxy-octadeca-1, 9-dien-4, 6-diyn (3) inhibited the production of NO in LPS-activated RAW 264.7 cells by suppressing the i-NOS enzyme expression. These new inhibitors of i-NOS expression may have potential in the treatment of endotoxemia and inflammation accompanied by the overproduction of NO.

Acetylene↗
PubMed1999

The Cox-Maze III procedure for atrial fibrillation associated with rheumatic mitral valve disease.

BACKGROUND: The surgical results of the Cox-Maze III procedure (CM-III) for atrial fibrillation (AF) associated with rheumatic mitral valve (MV) disease are not as good as the results from surgery for AF alone. METHODS: To assess the efficacy and safety of the CM-III in AF associated with rheumatic MV disease, we retrospectively analyzed 75 patients who underwent the CM-III combined with a rheumatic MV procedure between April 1994 and December 1997. Fourteen cases were reoperations because of prosthetic valve failure. RESULTS: Mean aortic cross-clamp (ACC) times and cardiopulmonary bypass (CPB) times were 151+/-43 and 251+/-73 min, respectively. Concomitant procedures were mitral valve replacement (MVR) in 25 patients, MVR and aortic valve replacement (AVR) in 14 patients, MV repair in 10 patients, MVR and tricuspid annuloplasty (TAP) in 6 patients, MVR and AV repair in 3 patients, MVR and coronary artery bypass grafting (CABG) in 2 patients, MVR and AVR and CABG in 1 patient, redo-MVR in 8 patients, redo-MVR and TAP in 4 patients, and redo-MVR and redo-AVR in 2 patients. There were two in-hospital mortalities (2 of 75, 2.7%). Seventy-three survivors were followed for a mean duration of 30+/-13 months (12-56 months). Normal sinus rhythm was restored in 90.4% (66 of 73). Three patients remained in AF and 2 patients were in junctional rhythm. Permanent pacemakers were implanted in 2 patients due to sick sinus syndrome. Right atrial (RA) contractility was demonstrable in 100% (66 of 66) and left atrial (LA) contractility in 62.1% (41 of 66) of the patients in the latest follow-up echocardiography. RA and LA contractilities were restored a mean 69+/-93 and 126+/-136 days after the operation, respectively. LA contractility was restored significantly later at a lower rate than RA contractility in rheumatic MV disease. There were no differences in ACC time, CPB time, incidence of postoperative bleeding complications, and sinus conversion rates between non-redo and redo cases in spite of the significantly longer duration of preoperative AF in redo cases (p<0.05). CONCLUSIONS: The CM-III for AF associated with rheumatic MV disease demonstrated a high sinus conversion rate with acceptable operative risk even in cases of reoperation.

Adult↗
PubMed1999

Placenta growth factor: potential role in pregnancy.

PROBLEM: In spite of the known requirement for adequate vascularity during placentation, little is known regarding the regulation of angiogenic growth factor production by trophoblast. Placenta growth factor (PIGF) is a recently discovered angiogenic growth factor whose expression is relatively limited to trophoblast. METHOD OF STUDY: Current literature of PIGF was reviewed, with emphasis on its expression, regulation, role in angiogenesis, and potential function(s) at the maternal-fetal interface. RESULTS: PIGF is abundantly expressed by trophoblast, which implies that it could act in a paracrine manner to modulate vascular development, stability, and/or function within the decidua and placental villi. In addition, expression of the PIGF receptor, fms-like tyrosine kinase (flt-1) receptor, on trophoblast raises the potential for an autocrine role of PIGF in regulating trophoblast growth and/or function. CONCLUSIONS: The potential for PIGF to influence both vascular endothelial cells and trophoblast suggests that aberrant trophoblast production of PIGF could compromise cellular function during gestation and contribute to the vascular and placental pathologies noted in many obstetric complications.

Female↗
PubMed1999

Doxorubicin-cisplatin chemotherapy for high-grade nonosteogenic sarcoma of bone. Comparison of treatment and control groups.

OBJECTIVE: To evaluate the role of chemotherapy with a combination of doxorubicin (adriamycin) and cisplatin in high-grade, nonosteogenic, non-Ewing's sarcoma (non-OSA) of bone. DESIGN: A case series comparison with a literature-derived control group. SETTING: A university-affiliated tertiary care centre. PATIENTS: Thirty patients with a diagnosis of non-OSA. Of these, 8 had low-grade disease (grade 1 or 2) and 22 had high-grade disease (grade 3). Eleven of the 22 with high-grade disease had malignant fibrous histiocytoma. Seventeen patients with nonmetastatic high-grade non-OSA were compared with a literature cohort of 37 patients who met the eligibility criteria of nonmetastatic, high-grade non-OSA treated with surgery, with or without radiotherapy. The mean follow-up was 25.2 months. INTERVENTIONS: Eight patients with low-grade tumour underwent surgery alone; 22 patients with high-grade tumour underwent surgery and 6 courses of adriamycin (75 mg/m2 every 3 weeks) and cisplatin (100 mg/m2 every 3 weeks). MAIN OUTCOME MEASURES: Disease-free survival and overall survival in those with high-grade tumours treated with or without chemotherapy. RESULTS: Of 8 patients who had low-grade tumours and underwent surgery alone, 3 had systemic relapse. Of the 22 having high-grade tumours, 4 did not receive chemotherapy because of age and comorbid conditions. Of the other 18, 13 received 3 courses of chemotherapy preoperatively and 3 courses postoperatively, 4 received all 6 courses postoperatively and 1 received all chemotherapy preoperatively to treat metastatic disease. In the 17-patient cohort used for comparison with the literature control group, disease-free survival was 57% at a mean follow-up of 25.6 months and overall survival was 57% at a mean follow-up of 30.1 months. In the control group, disease-free survival was 16% at a mean follow-up of 20.9 months and overall survival was 26% at a mean follow-up of 29.9 months. These differences are significant: p = 0.0000, chi 2 = 41.61 for disease-free survival and p = 0.0000, chi 2 = 46.49 for overall survival. CONCLUSIONS: The findings of this study support the use of adjuvant chemotherapy in patients with high-grade non-OSA, in whom malignant fibrous histiocytoma was the predominant histologic subtype.

Adolescent↗
PubMed1998

Regional changes of NADPH-diaphorase and neuropeptide Y neurons in the cerebral cortex of aged Fischer 344 rats.

This study examined the effects of aging on neuropeptide Y (NPY) and NADPH-diaphorase (NADPH-d)-positive neurons of the cerebral cortex in young (3 months) and aged (24 months) Fischer 344 rats by immunohistochemical and histochemical methods. In the aged group, the number of NPY-immunoreactive (IR)/NADPH-d-positive neurons was not significantly changed in all regions of the cerebral cortex compared to the control group. However, the number of NPY-IR/NADPH-d-negative neurons was significantly decreased in frontal association, primary motor, secondary somatosensory, insular, ectorhinal, perirhinal and auditory cortex in the aged group. In the aged rats, about 5-10% of NPY-IR/NADPH-d-positive neurons were dystrophic and scattered within the cerebral cortex. These results suggested that NPY-IR neurons that do not contain NADPH-d are affected by aging and that aging influences NPY-IR/NADPH-d-negative neurons in a region-specific pattern within the cerebral cortex of rats.

Aging↗
PubMed1998

Lacrimal system obstruction treated with lacrimal polyurethane stents: outcome of removal of occluded stents.

PURPOSE: To describe the short- and long-term outcomes of the removal of occluded stents. MATERIALS AND METHODS: With fluoroscopic guidance, 571 lacrimal polyurethane stents were placed in 502 patients with epiphora due to obstruction of the lacrimal system. Of the 571 stents, 142 were removed 2 weeks to 42 months (mean, 7 months) after placement because of recurrent epiphora, and the lacrimal system was irrigated with saline solution through the lacrimal point. RESULTS: Stent removal was well tolerated. Mild epistaxis occurred in one patient and was controlled with a nasal pack. Recurrent epiphora was due to obstruction of the stent with mucoid material in 49 (35%) of 142 systems and granulation tissue in 93 (65%) systems. After stent removal, 73 (51%) of the 142 lacrimal systems showed improvement of epiphora, with a patent lacrimal system at 7-day follow-up dacryocystography. During the follow-up of 2 weeks to 49 months (mean, 22 months) after stent removal, patency was maintained in 24 (33%) of the 73 lacrimal systems. CONCLUSION: Removal of an occluded lacrimal plastic stent was easy and safe. Recurrent epiphora after placement of lacrimal plastic stents can be treated with removal of the occluded stents an irrigation with saline solution through the lacrimal point, which resulted in a patent lacrimal system in 33% of cases in this study.

Adult↗
PubMed1998

Alpha-fetoprotein producing renal cell carcinoma: a case report.

We report a case of alpha-fetoprotein (AFP) producing renal cell carcinoma. A 53-year-old man with fever was found to have a left renal mass on computed tomography. No mass was detected in the liver. Serum AFP was 1,460 ng/ml. Radical nephrectomy showed a 10 cm mass in the upper half. A half of the tumor was whitish yellow and firm whereas another half was soft and bright yellow with hemorrhagic and necrotic areas. Histologically, the two areas were different. The lower part consisted of the clear cell renal cell carcinoma and the upper part consisted of granular cells. On immunohistochemistry, the granular tumor cells only were positive for AFP. Serum AFP level dropped abruptly to 383 ng/ml on the 6th postoperative day and gradually returned to normal during the 6 months. Multiple metastatic nodules were found in the lungs, liver and bone in 9th postoperative month and the AFP was less than 1 ng/ml. This suggest metastatic lesions are non-AFP producing clear cell type. It can be concluded that serum AFP elevation was due to synthesis by the renal cell carcinoma in the absence of liver neoplasm. Although AFP producing renal cell carcinoma is a rare entity, serum AFP can be a useful marker for the detection of the tumor.

Carcinoma, Renal Cell↗
PubMed1997

Differential effects of aging on NADPH-diaphorase and VIP neurons in cerebral cortex of rats.

Age-related changes of NADPH-diaphorase (NADPH-d) and vasoactive intestinal polypeptide (VIP) were examined in the rat brain. Aged (24 months) rats showed a significant decrease in the number of VIP-immunoreactive (IR) neurons in the cerebral cortex when compared with control (4 months) rats. However, the number of NADPH-d-positive neurons was not significantly different in the two groups. Quantitative analysis of cell areas revealed a significant shrinkage of VIP-IR neurons in the aged group, whereas no further cell shrinkage was noted for NADPH-d-positive neurons compared with the control group. These morphometric results demonstrate that NADPH-d-containing neurons are more resistant to aging than the VIP-IR neurons in the cerebral cortex of rats.

Aging↗
PubMed1997

Age-related change in the neuropeptide Y and NADPH-diaphorase-positive neurons in the cerebral cortex and striatum of aged rats.

Age-related changes of neuropeptide Y (NPY) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) were examined in the rat cerebral cortex and striatum by immunohistochemical and histochemical methods. Double labeling for NPY and NADPH-d showed that about 30-70% of NPY-immunoreactive (NPY-IR) neurons in the cerebral cortex of the control (4-month-old) rats contained NADPH-d and that 50-75% in the aged (24-month-old) rats. The aged rats showed a significant increase in percentage of colocalization of NPY and NADPH-d in comparison with the control rats in the temporal cortex, occipital cortex, cingulate cortex, insular cortex, retrosplenial cortex and caudatoputamen. However, colocalization percentage between control and aged rats in the frontal cortex, parietal cortex, perirhinal cortex, entorhinal cortex and nucleus accumbens were practically identical. In the aged group, the number of NPY-IR/NADPH-d-positive neurons was not significantly decreased in the cerebral cortex and striatum compared to the control group. However, the number of NPY-IR/NADPH-d-negative neurons was significantly decreased in all cerebral cortical areas and caudatoputamen in the aged group except in the nucleus accumbens. Major loss of NPY-IR/NADPH-d-negative neurons in the aged group were observed in the neurons of layer II/III and V/VI. These results demonstrate that the NADPH-d containing NPY-IR neurons are less influenced by aging than the control group in the cerebral cortex and striatum of rats.

Aging↗
PubMed1997

Surgical management of type A aortic dissection: evaluation of predisposing factors for postoperative neurologic complication and late reoperation.

The technique of cerebral protection during hypothermic circulatory arrest remains controversial. Forty-seven patients underwent operations for type A aortic dissection in the past 9 years. During hypothermic circulatory arrest, selective cerebral perfusion and retrograde cerebral perfusion was applied in 12 and seven patients, respectively. The mortality rate was 28.6% in patients without adjunctive cerebral perfusion, 25.0% in selective cerebral perfusion patients, and zero in the retrograde cerebral perfusion group (P > 0.05). However, there was no mortality by cerebral injury in cerebral perfusion groups (P = 0.03). Age (P = 0.001), hypothermic circulatory arrest time (P = 0.012), and acuity (P = 0.013) were predisposing factors for cerebral injury, but cerebral perfusion has not yet been found to be a protective factor (P = 0.56). Nine late reoperations and three deaths occurred during the follow-up period. Marfan syndrome was the only predisposing factor for late reoperation (P = 0.016). In summary, although further studies are still required, retrograde cerebral perfusion is a possible cerebral protective factor. In addition, periodic follow-up is mandatory, especially in patients with Marfan syndrome.

Adolescent↗
PubMed1997

Atherosclerotic risk factors are less intensively treated in patients with peripheral arterial disease than in patients with coronary artery disease.

OBJECTIVE: To compare rates of therapy for atherosclerotic risk factors between patients with lower extremity peripheral arterial disease (PAD) and patients with coronary artery disease (CAD). DESIGN: Cross-sectional. SETTING: Academic medical center. PATIENTS/PARTICIPANTS: Three hundred forty-nine consecutive patients diagnosed with PAD or CAD identified from the blood flow and cardiac catheterization laboratories, respectively. MEASUREMENTS AND MAIN RESULTS: Participants were interviewed by telephone for medical history as well as therapies prescribed and recommended by their physicians. Among patients with hypercholesterolemia, more CAD patients were taking cholesterol-lowering drugs (58% vs 46%, p = .08) and more CAD patients recalled a physician's instruction to follow a low-fat, low-cholesterol diet (94% vs 83%, p = .01). CAD patients were more likely to exercise regularly (71% vs 50%, p < .01). Among patients not exercising, more CAD patients recalled a physician's advice to exercise (74% vs 47%, p < .01). In logistic regression analysis, hypercholesterolemic patients with exclusive CAD were more likely to be treated with drug therapy (odds ratio [OR] 2.3, p = .05). CAD patients were more likely to recall advice to exercise (OR 4.0, p < .001), and more likely to be taking aspirin or warfarin (OR 4.8, p = .01). CONCLUSIONS: Atherosclerotic risk factors are less intensively treated among PAD patients than CAD patients. A number of possible explanations could account for these disparities in therapeutic intensity.

Aged↗
PubMed1997

Tree-structured logistic models for over-dispersed binomial data with application to modeling developmental effects.

This article proposes tree-structured logistic regression modeling for over-dispersed binomial data. Recursive partitioning is performed using a combination of statistical tests and residual analysis. The splitting criterion in cross-validation is based on the deviance function. A nested grid algorithm to estimate the bootstrap parameters is developed. The regression tree procedure provides a new approach for exploring in detail the relationship between the binomial response and explanatory variables. The proposed procedure is used to model the relationship between the incidence of malformation and dose and fetal weight using data from a developmental experiment conducted at the National Center for Toxicological Research. A conditional Gaussian chain model is used to account for the effect of fetal weight by dose.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1997

An age-adjusted trend test for the tumor incidence rate for multiple-sacrifice experiments.

The nonparametric age-adjusted trend test for the tumor incidence rate proposed by Malani and Lu (1993, Communications in Statistics--Theory and Methods 22, 1557-1584) is modified in two ways to improve the size of the test. First, the tumor incidence rate is constrained to be nonnegative, and second, a conditional variance is used in place of the asymptotic variance based on the delta method. A Monte Carlo simulation study demonstrates the improvement in size of test. The proposed test can be viewed also as a modification of the two-group test of Dewanji and Kalbfleisch (1986, Biometrics 42, 325-341), although their maximum likelihood routine is based on a different formulation of the problem.

Age Factors↗
PubMed1996

Distinct regulatory roles of lymphocyte costimulatory pathways on T helper type-2 mediated autoimmune disease.

We assessed the role of CD40-CD40L, cytotoxic T lymphocyte (CTL)A4/CD28-B7s, and CD2-CD48/CD58 lymphocyte costimulatory pathways in the development of mercury chloride (HgCl2)-induced autoimmune disease in mice, which is believed to be mediated by T helper (Th) subset Th2. Inhibition of CD40-CD40-L and CTLA4/CD28-B7s interactions by anti-CD40-L antibody and soluble CTLA4-immunoglobulin (Ig) fusion protein, respectively, abrogated the autoimmune disease without affecting interleukin 4 (IL-4) production, showing the importance of physical contact between T and B lymphocytes in the Th2-mediated process. In contrast, two anti-CD2 antibodies that have been shown to induce immunosuppression of Th1-mediated events exacerbated the autoantibody response and augmented IgG1, IgE, and IL-4 production, transforming a mild mesangial glomerulopathy into a severe systemic immune complex disease. These observations demonstrate that manipulation of lymphocyte accessory counterreceptor interactions may affect the course of Th2-associated autoimmune disease and suggest that signals resulting from CD2 engagement play an essential role in the regulation of the Th1-Th2 effector equilibrium.

Animals↗