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Biomedical subjects

H Jeong

Publications and source records attributed to H Jeong.

At least 19 recordsLinked to original sources
PubMed2001

Weighted evolving networks.

Many biological, ecological, and economic systems are best described by weighted networks, as the nodes interact with each other with varying strength. However, most evolving network models studied so far are binary, the link strength being either 0 or 1. In this paper we introduce and investigate the scaling properties of a class of models which assign weights to the links as the network evolves. The combined numerical and analytical approach indicates that asymptotically the total weight distribution converges to the scaling behavior of the connectivity distribution, but this convergence is hampered by strong logarithmic corrections.

Mathematical Computing↗
PubMed2001

Inhibition of lipid peroxidation and oxidative DNA damage by Ganoderma lucidum.

Reactive oxygen species (ROS), such as superoxide anions and hydroxyl radicals, are associated with carcinogenesis and other pathophysiological conditions. Therefore, elimination or inactivation of ROS or inhibition of their excess generation may be beneficial in terms of reducing the risk for cancer and other diseases. Ganoderma lucidum has been used in traditional oriental medicine and has potential antiinflammatory and antioxidant activities. In the present study, we tested the amino-polysaccharide fraction (designated as 'G009') from Ganoderma lucidum for the ability to protect against oxidative damage induced by ROS. G009 significantly inhibited iron-induced lipid peroxidation in rat brain homogenates and showed a dose-dependent inactivation of hydroxyl radicals and superoxide anions. It also reduced strand breakage in phiX174 supercoiled DNA caused by UV-induced photolysis of hydrogen peroxide and attenuated phorbol ester-induced generation of superoxide anions in differentiated human promyelocytic leukaemia (HL-60) cells. These findings suggest that G009 from Ganoderma lucidum possesses chemopreventive potential.

Animals↗
PubMed2001

IgE-mediated occupational asthma induced by herbal medicine, Banha (Pinellia ternata).

There have been few reported cases of occupational asthma induced by Pinellia ternata (Banha), and the mechanism responsible for this type of asthma is still undetermined. We report a case of Banha-induced occupational asthma with IgE-mediated mechanism. The patient had positive skin responses to Banha extract and Banha-specific bronchial challenge elicited an early asthmatic response. The serum-specific IgE binding to Banha extract was detectable and completely inhibited with the additions of 0.1 microg/mL of Banha extract on ELISA inhibition. Seven IgE binding components to Banha extract (6.5, 22, 24, 32, 34, and 48 kDa) were detected using SDS-PAGE and immunoblot analysis. In conclusion, the results of this study suggest that P. ternata (Banha)-derived allergens are able to cause IgE-mediated bronchoconstriction in exposed workers.

Adult↗
PubMed2001

Immunohistochemical analysis of CD44s and CD44v6 in endometriosis and adenomyosis : comparison with normal, hyperplastic, and malignant endometrium.

The expression patterns of CD44s and CD44v6 were immunohistochemically compared with those of normal, hyperplastic and malignant endometrium. In normal endometria (n=37), endometrioses (n=46) and adenomyoses (n=20), the surface and glandular epithelial cells were negative for CD44s and CD44v6 in a proliferative pattern and positive in a secretory pattern, whereas the stroma was only positive for CD44s in both proliferative and secretory patterns. The endometrial hyperplasia (4 simple and 9 complex) had the identical patterns with normal proliferative phase of endometrium. Only one case showing complex hyperplasia with atypia was focally positive for CD44s and CD44v6 in glandular epithelia. CD44s and CD44v6 were positive in all endometrial adenocarcinomas (13), except one CD44s-negative case. In summary, the expressions of CD44s and CD44v6 in endometriosis and adenomyosis recapitulated those of normal cyclic endometrium. The expression patterns in endometrial hyperplasia were similar to those in normal proliferative endometrium, whereas the endometrial adenocarcinoma showed abnormal expressions for CD44s and CD44v6. Thus it was considered that the ectopic endometrium in endometriosis and adenomyosis was not aberrant as in endometrial carcinoma on the aspects of immunohistochemical expressions of CD44s and CD44v6.

Adenocarcinoma↗
PubMed2001

Extracellular polymeric substances in relation to nutrient removal from a sequencing batch biofilm reactor.

Experimental investigations were performed to determine the possibility of simultaneous biological nitrogen and phosphorus removal during various biofilm processes in conjunction with biofilm characterisation, especially extracellular polymeric substance (EPS). Since biologial nitrogen removal requires an alternating exposure of anaerobic-anoxic-oxic conditions in the bulk liquid that surrounds the biofilm growth media, a sequencing batch reactor (SBR)-type operation was used. Various materials including expanded clay, polystyrene, polyurethane, and acrylic materials were used as the biofilm growth support medium. Simultaneous nitrogen and phosphorus removal was possible with SBR, but it was postulated that nutrient removal efficiencies varied with film thickness. Thinner biofilm promoted nitrification and phosphorus removal, but thicker biofilm enhanced denitrification and reduced phosphorus removal. EPS contents were similar regardless of support media types or biofilm configuration, but EPS contents gradually increased as the film growth continued after backwashing. EPS contents were increased with increased nitrogen removal, but it was difficult to define its relation with phosphorus removal. In addition, suspended solids removal was correlated well with the EPS content in the biofilms.

Biofilms↗
PubMed2000

The large-scale organization of metabolic networks.

In a cell or microorganism, the processes that generate mass, energy, information transfer and cell-fate specification are seamlessly integrated through a complex network of cellular constituents and reactions. However, despite the key role of these networks in sustaining cellular functions, their large-scale structure is essentially unknown. Here we present a systematic comparative mathematical analysis of the metabolic networks of 43 organisms representing all three domains of life. We show that, despite significant variation in their individual constituents and pathways, these metabolic networks have the same topological scaling properties and show striking similarities to the inherent organization of complex non-biological systems. This may indicate that metabolic organization is not only identical for all living organisms, but also complies with the design principles of robust and error-tolerant scale-free networks, and may represent a common blueprint for the large-scale organization of interactions among all cellular constituents.

Animals↗
PubMed2000

Error and attack tolerance of complex networks

Many complex systems display a surprising degree of tolerance against errors. For example, relatively simple organisms grow, persist and reproduce despite drastic pharmaceutical or environmental interventions, an error tolerance attributed to the robustness of the underlying metabolic network. Complex communication networks display a surprising degree of robustness: although key components regularly malfunction, local failures rarely lead to the loss of the global information-carrying ability of the network. The stability of these and other complex systems is often attributed to the redundant wiring of the functional web defined by the systems' components. Here we demonstrate that error tolerance is not shared by all redundant systems: it is displayed only by a class of inhomogeneously wired networks, called scale-free networks, which include the World-Wide Web, the Internet, social networks and cells. We find that such networks display an unexpected degree of robustness, the ability of their nodes to communicate being unaffected even by unrealistically high failure rates. However, error tolerance comes at a high price in that these networks are extremely vulnerable to attacks (that is, to the selection and removal of a few nodes that play a vital role in maintaining the network's connectivity). Such error tolerance and attack vulnerability are generic properties of communication networks.

Journal Article↗
PubMed2000

Quasi-unit-cell model for an Al-Ni-Co ideal quasicrystal based on clusters with broken tenfold symmetry

We present new evidence supporting the quasi-unit-cell description of the Al72Ni20Co8 decagonal quasicrystal which shows that the solid is composed of repeating, overlapping decagonal cluster columns with broken tenfold symmetry. We propose an atomic model which gives a significantly improved fit to electron microscopy experiments compared to a previous proposal by us and to alternative proposals with tenfold symmetric clusters.

Journal Article↗
PubMed2000

Depinning of an anisotropic interface in random media: the tilt effect

We study the tilt dependence of the pinning-depinning transition for an interface described by the anisotropic quenched Kardar-Parisi-Zhang equation in 2+1 dimensions, where the two signs of the nonlinear terms are different from each other. When the substrate is tilted by m along the positive sign direction, the critical force F(c)(m) depends on m as F(c)(m)-F(c)(0) approximately -|m|(1.9(1)). The interface velocity v near the critical force follows the scaling form v approximately |f|(straight theta)Psi(+/-)(m(2)/|f|(straight theta+straight phi)) with straight theta=0.9(1) and straight phi=0.2(1), where f identical withF-F(c)(0) and F is the driving force.

Journal Article↗
PubMed1998

Penile sensitivity in men with premature ejaculation.

Premature ejaculation is the most prevalent form of male sexual dysfunction, but its cause has not been well established. Recent studies have indicated that in men with premature ejaculation, penile sensitivity is increased. To investigate whether penile hypersensitivity is a cause of premature ejaculation, we prospectively evaluated the penile sensitivity of 18 patients with a lifelong history of premature ejaculation from the first coital experience and 15 controls, both in the flaccid and erect state. We used an SMV-5 vibrometer (Suzuki-Matsuoka, Teknologue, Tokyo, Japan), which automatically controls stimulatory strength; its precision and reproducibility are thus higher than analogue-type biothesiometers. At the styloid process of the ulna and medial maleolus of the tibia, there was no significant statistical difference in vibratory threshold between the two groups (P > 0.05). Also we did not find significant statistical differences in sensitivity of the glans penis, dorsum of the penile shaft, or frenulum of the penis between the two groups, in either the flaccid or erect state (P > 0.05). According to our results, penile hypersensitivity, as measured by an SMV-5 vibrometer, does not appear to be a major factor contributing to premature ejaculation.

Adult↗
PubMed1996

An allograft kidney showing both features of IgA nephropathy and membranous glomerulonephritis--a case report.

We report a case of glomerular disease with both mesangial IgA and subepithelial IgG deposits in the allograft kidney. The patient was a 36 year-old man who had received a renal allograft 1 year previously. Fifteen days before admission, he discovered a microscopic hematuria without clinical evidences of allograft rejection. Light microscopy showed diffuse increase of mesangial matrix without mesangial cell proliferation. Capillary walls were diffusely and mildly thickened. Immunofluorescence microscopy demonstrated both granular deposits of IgA in the mesangium and IgG along the capillary walls. On electron microscopy, electron-dense deposits were identified not only in the mesangium but also on the epithelial side of the glomerular basement membrane.

Adult↗
PubMed1993

Manning criteria in irritable bowel syndrome: its diagnostic significance.

BACKGROUND: Irritable bowel syndrome is one of the most commonly encountered gastrointestinal disorders, for which there are no established diagnostic criteria. Thus, a diagnosis of IBS is made by exclusion of any organic diseases. Recently, important attempts for the positive diagnosis of irritable bowel syndrome by questionnaire surveys of physical symptoms have been made. We performed a questionnaire survey to evaluate the diagnostic value of the Manning criteria and to observe the major symptoms in irritable bowel syndrome. METHODS: A symptom questionnaire which consisted of 22 items, including 6 cardinal symptoms of the Manning criteria, were answered by 172 outpatients who had gastrointestinal complaints. According to a final diagnosis based on independent clinical evaluation, all patients were categorized in three groups: irritable bowel syndrome group, nonulcer dyspepsia group and organic gastrointestinal disease group. The results of the questionnaire were analyzed for each group. RESULTS: The sensitivity and specificity of the Manning criteria for the diagnosis of irritable bowel syndrome were 67% and 70% if three or more items were regarded as positive. The mean score and overall frequency of the Manning criteria were significantly higher in irritable bowel syndrome group than in nonuclear dyspepsia (p < 0.01) or organic gastrointestinal disease group (p < 0.05). Among subgroups of the irritable bowel syndrome group, the pain-predominant subgroup showed a significantly higher score and overall frequency than the painless subgroup (p < 0.05). CONCLUSIONS: The Manning criteria would be useful as a simple and reliable backup tool for the diagnosis of irritable bowel syndrome and seem to be more useful in pain-predominant subgroup. More detailed history-taking should prevent unnecessary extensive investigations for the diagnosis of irritable bowel syndrome.

Adolescent↗
PubMed1992

Prevalence of antibodies to hepatitis C virus in patients with various types of liver diseases.

BACKGROUND: Hepatitis C virus (HCV) is known to be a major cause of non-A, non-B hepatitis (NANBH) and is thought to be an important causative agent of serious liver disease. Recently the role of HCV in the development of various liver disease is suggested. METHODS: Sera from 222 patients with various liver diseases had been kept frozen at -20 degrees C until the test. Anti-HCV was detected using the ABBOTT HCV EIA Test System (ABBOTT Co., America) following the manufacturer's instructions. The assay uses a recombinant HCV antigen (C 100-3) synthesized in yeast. RESULTS: HCV antibodies (anti-HCV) were detected in 35 (31.5%) of 111 HBsAg-negative patients. The prevalence rate of anti-HCV was 61.9% (13 out of 21 patients) in chronic hepatitis, 29.1% (14 out of 48) in liver cirrhosis, 26.3% (5 out of 19) in hepatocellular carcinoma and 13% (3 out of 23) in acute hepatitis was far less (3 out of 111 patients, 2. 7%) than that of HBsAg-negative patients (p < 0.01). In this group, anti-HCV was detected in 2 (5.1%) out of 39 liver cirrhosis, 1 (1.9%) out of 52 chronic hepatitis, among them 47 were biopsy-proven chronic active hepatitis, and none of 20 hepatocellular carcinoma. CONCLUSIONS: These data suggest that, in Korea, 1) coinfection of HCV and HBV is infrequent, 2) HCV might be an important cause of HBsAg-negative chronic hepatitis, 3) HCV is seemed to be a less likely important factor associated with liver cirrhosis or hepatocellular carcinoma in HBsAg-negative patients, but further prospective study with a large population is necessary.

Female↗