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Biomedical subjects

S G Hong

Publications and source records attributed to S G Hong.

14 recordsLinked to original sources
PubMed2006

Birth of viable female dogs produced by somatic cell nuclear transfer.

Since the only viable cloned offspring born in dogs was a male, the purpose of the present study was to produce female puppies by somatic cell nuclear transfer (SCNT). Adult ear fibroblasts from a 2-month-old female Afghan hound were isolated and used as donor cells. In vivo-matured canine oocytes surgically collected (approximately 72h after ovulation) from the oviducts of 23 donors were used for SCNT. After removal of the cumulus cells, oocytes were enucleated, microinjected, fused with a donor cell, and activated. A total of 167 reconstructed SCNT embryos were surgically transferred (Day 0) into the oviducts of 12 recipient bitches (average 13.9 embryos/recipient, range 6-22) with spontaneous, synchronous estrous cycles. Three pregnancies were detected by ultrasonography on Day 23, maintained to term, and three healthy female puppies (520, 460, and 520g), were delivered by Caesarean section on Day 60. These puppies were phenotypically and genotypically identical to the cell donor. In conclusion, we have provided the first demonstration that female dogs can be produced by nuclear transfer of ear fibroblasts into enucleated canine oocytes.

Animals↗
PubMed2006

Soluble microbial products (SMP) and soluble extracellular polymeric substances (EPS) from wastewater sludge.

Laspidou and Rittmann (Water Research 36:2711-2720, 2002) proposed that the soluble extracellular polymeric substances (EPS) are identical to soluble microbial products (SMP) in sludge liquor. In this paper, we compared the physicochemical characteristics of the SMP and soluble EPS from original and aerobically or anaerobically digested wastewater sludge. The surface charges, particle sizes, residual turbidities of polyaluminum chloride (PACl) coagulated supernatant, and chemical compositions of the SMP and soluble EPS containing suspensions were used as comparison index. Experimental results revealed that the particles in SMP and soluble EPS fractions extracted from original wastewater sludge, before and after digestion, were not identical in all physicochemical characteristics herein measured. The current test cannot support the proposal by Laspidou and Rittmann (Water Research 36:2711-2720, 2002) that SMP is identical to the soluble EPS from a wastewater sludge.

Aerobiosis↗
PubMed2001

In vitro anti-proliferative effect of 1,2,3,4,6-penta-O-galloyl-beta-D-glucose on human hepatocellular carcinoma cell line, SK-HEP-1 cells.

The root of Paeonia suffruticosa ANDREWS is an important Chinese crude drug used in many traditional prescriptions. 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG), a major component of this crude drug, was found to exhibit in vitro growth-inhibiting effect on human hepatocellular carcinoma cell line, SK-HEP-1 cells. The growth-inhibitory effect was related to the ability of PGG not only to cause a G(0)/G(1) phase arrest but also to suppress the activation of nuclear factor-kappa B. Neither apoptosis nor necrosis was observed in the cells treated with PGG. These findings suggest that PGG could be a candidate for developing a low-toxic anticancer agent.

Antineoplastic Agents↗
PubMed2001

Mistletoe lectin synergizes with paclitaxel in human SK-hep1 hepatocarcinoma cells.

The effect of mistletoe lectin I (ML-I), an inhibitor of ribosomal protein synthesis, on the in vitro cytotoxicity of a clinically important anticancer drug, paclitaxel, was studied on cultured human hepatocarcinoma SK-Hep1 cells using the microculture tetrazolium test. The interaction between these two agents was analyzed for true synergism using the ED50 isobologram. Synergism was observed in the simultaneous treatment of the cells with ML-I in combination with paclitaxel. In addition, 24-h exposure of the cells to a non-toxic dose of ML-I and lower toxic doses of paclitaxel in combination resulted in apoptotic cell death, as observed by agarose-gel electrophoresis of low-molecular-weight DNA and DNA flow cytometry. Thus, the results presented here indicate the potential clinical usefulness of ML-I combination therapy with paclitaxel.

Adjuvants, Immunologic↗
PubMed2001

[Differentiation of human hepatocarcinoma SMMC-7721 cells induced by HMBA].

In this paper, the effects of HMBA on the differentiation of human hepatocarcinoma cell line SMMC-7721 were investigated. After treated with 5 mmol/L HMBA, the proliferation of SMMC-7721 cells was inhibited remarkably, the cell growth inhibitory rate amounted to 64.14%, the cell mitotic index was declined by 53.88%. Light microscopy and transmission electron microscopy showed that the morphology and ultrastructure of the cells treated with HMBA undergone restorational alteration. Cytochemistry and immunocytochemistry assay revealed that the activities of gamma-GT declined and the levels of AFP and PCNA downregulated while the activity of TAT increased significantly after HMBA treatment. In the meantime, flow cytometry analysis showed that HMBA could arrest the cells in G0/G1 phase. The results showed that HMBA could effectively inhibit the proliferation, reverse the malignant morphology and ultrastructure, alter the levels of enzymes and antigens, arrest the cells in G0/G1, and induce the differentiation of human hepatocarcinoma SMMC-7721 cells in vitro.

Acetamides↗
PubMed2000

Protective effects of Orostachys japonicus A. Berger (Crassulaceae) on H2O2-induced apoptosis in GT1-1 mouse hypothalamic neuronal cell line.

Oxidative stress is a major cause of neurodegenerative diseases, so the protection of neuronal cells from reactive oxygen species can be beneficial for the prevention and treatment of these diseases. Methanol extract of Orostachys japonicus A. Berger (Crassulaceae), a traditional oriental medical herb, was shown to have a protective effect on H2O2-induced apoptosis in GT1-1 mouse hypothalamic neuronal cell line which was detected by flow cytometry after propidium iodide staining. Among fractions of O. japonicus, chloroform fraction had the highest protective effect, and water fraction had no protective effect suggesting that the active ingredients might be hydrophobic compounds.

Animals↗
PubMed1996

Regulation of atrial muscarinic K+ channel activity by a cytosolic protein via G protein-independent pathway.

Rapid desensitization of the muscarinic K+ current (KACh current) is observed in cell-attached patches with 10 microM acetylcholine in the pipette. When inside-out patches were formed within approximately 1 s after formation of cell-attached patches and GTP was applied to the cytoplasmic side of the membrane, desensitization was not observed, indicating that a cytosolic factor mediated the desensitization. Applying the atrial cytosolic extract directly to the cytoplasmic side of such inside-out patches elicited a rapid desensitization of the KACh current. ATP (1-4 mM) reversed this effect of the cytosol and reverted the KACh channel to the undesensitized state. These effects of ATP and cytosol on the KACh channel could occur in the absence of GTP or in the presence of 100 microM guanosine 5'-O-(3-thiotriphosphate), indicating that G protein was not involved. Treatment of the cytosol with proteases (trypsin, chymotrypsin, bacterial protease) or heat denaturation abolished the effect of the cytosol on the KACh channel kinetics, indicating that the cytosolic factor was a protein. Functional assay of the fractions collected from gel filtration column indicated that the molecular mass of the native protein was 95-130 kDa. We conclude that a large cytosolic protein mediates the rapid desensitization of the KACh channel current via a G protein-independent pathway.

Adenosine Triphosphate↗
PubMed1982

Rapid increase in deep supercooling of xylem parenchyma.

Malus pumila Mill. twigs were collected from September through December and stored at 5 degrees C until the low temperature exotherms of the xylem were determined by differential thermal analysis. During the differential thermal analysis, cooling was interrupted, and temperatures of 5 to -18 degrees C were held for 0.4 to 10 hours before cooling to -50 degrees C was resumed. Control twigs were cooled to -50 degrees C without interruption. Holding the twigs at 1.3 to -5 degrees C shifted the start of the low temperature exotherm from about -20 to -30 degrees C. Slightly higher (2.6 degrees C) and lower (-10 degrees C) temperatures were occasionally effective. The shift began within 20 to 30 minutes and increased progressively to 150 minutes. The acclimation was reversibly inhibited by N(2) atmosphere.

Journal Article↗
PubMed1980

Units of freezing of deep supercooled water in woody xylem.

The low temperature exotherms (LTE) of 1-year-old twigs of Haralson apple (Malus pumila Mill.), shagbark hickory (Carya ovata [Mill.] K. Koch), green ash (Fraxinus pennsylvanica Marsh), honey locust (Gleditsia triacanthos L.), American chestnut (Castanea dentata [Marsh] Borkh.), and red oak (Quercus rubra L.) were determined by differential thermal analysis (DTA). In one type of experiment freezing during a DTA experiment was halted for up to 2.5 hours after part of the supercooled water had frozen at temperatures between -25 and -42 C. Upon resumption of cooling the freezing started within 2 C of the stopping temperature. In a second type of experiment living and dead cells were microscopically observed in the same ray after partial freezing in the DTA apparatus. In another experiment, the LTE persisted even after tangential and radial sectioning of the twig to 0.13 millimeters. In a final experiment the LTE of a single multiseriate ray of red oak had the same shape as the LTE of wood with many uniseriate rays.These experiments confirm that the deep supercooled water in woody xylem or pith freezes in numerous independent events over a span of as much as 20 C. The units which freeze in an event are single cells or small groups of cells. Ice grows very slowly if at all from these units, and water moves very slowly from unfrozen cells to frozen ones. Deep supercooling of ray parenchyma does not require an intact ray.

Journal Article↗
PubMed1976

Effects of kinetin and root tip removal on exudation and potassium (rubidium) transport in roots of honey locust.

Exudation, (86)Rb transport, and water permeability were examined in excised roots of honey locust (Gleditsia triacanthos L.) treated by removing the tip 2 mm (tip-cut 2 mm) or tip 8 mm of the root, or by adding kinetin, or by both treatments. Tip removal increased the rate of exudation. Kinetin, 5 x 10(-6)m, inhibited exudation and Rb transport in tip-cut 2-mm roots; the inhibition was reversible. Kinetin inhibition of exudation was initially associated with lower K(Rb) transport and later with decreases in both ion transport and water permeability. Exudation was also inhibited at 10(-10) to 10(-7)m kinetin. Exudation from roots with intact tips was not altered by kinetin until after about 24 hours. Light during the exudation period had no significant (95%) influence on rate of exudation during the first 24 hours whether root tips were cut or kinetin applied.The results suggest the involvement of the root tip in regulating exudation in other parts of the root. This regulation might occur through cytokinin control of water permeability and the rate of ion transport.

Journal Article↗