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Biomedical subjects

S H Song

Publications and source records attributed to S H Song.

At least 19 recordsLinked to original sources
PubMed2003

Cell uptake and tissue distribution of radioiodine labelled D-luciferin: implications for luciferase based gene imaging.

Optical luciferase gene imaging is emerging as a method to monitor gene expression in small animals. However, there is concern over how regional availability of exogenously administered substrate may affect photon emission. We thus synthesized [125I]iodo-D-luciferin, which demonstrated substrate characteristics for firefly luciferase, and investigated its cell uptake kinetics and in vivo biodistribution. Luminescence assays of luc gene transduced cells confirmed a linear decline in emitted light units with decreasing luciferin concentration. Both luc gene transduced and control cells demonstrated a low level of cellular uptake and rapid washout of [125I]iodo-D-luciferin, although early uptake was slightly higher for transduced cells (P < 0.005). Biodistribution in ICR mice demonstrated that early uptakes in liver, lung, myocardium and muscle were lower with intraperitoneal compared to intravenous administration. In view of the poor cell uptake, uptake levels (< 3%ID/g) suggest that substrate concentration may limit light emission rates in organs such as bone, muscle, myocardium, and particularly the brain. Thus, substrate availability should be considered as a potential limiting factor for photon emission efficiency in certain organs when attempting quantitative interpretation of optical luc gene imaging.

Animals↗
PubMed2001

DNA transfection using linear poly(ethylenimine) prepared by controlled acid hydrolysis of poly(2-ethyl-2-oxazoline).

A series of linear poly(ethylenimine) (L-PEI) containing varying amounts of cationic charge density in its backbone was produced by controlled hydrolysis of poly(2-ethyl-2-oxazoline) (PEtOz) for using as a nonviral DNA transfection agent. The effects of cationic charge density and molecular weight of the L-PEI on the cytotoxicity and transfection efficiency were studied. The efficiency of transfection was monitored by using a luciferase reporter gene system. Gel retardation assay and dynamic light scattering (DLS) showed that the condensation capacity of L-PEI was suitable for transfection. Highly compacted L-PEI/DNA complex ( approximately 150 nm) was obtained with a surface charge value of around +28.4 mV. Cell cytotoxicity was affected to a great extent by the hydrolysis percent of L-PEI as well as by the molecular weight. Transfection efficiency of luciferase plasmid DNA against NIH 3T3 fibroblast was largely dependent upon the hydrolysis percent (charge density) in the polymer backbone and the molecular weight of the L-PEI, but independent of the total amount of cationic charges used for DNA condensation. L-PEI with a hydrolysis percent of 88.0% exhibited comparable transfection efficiency to that of commonly used branched PEI.

3T3 Cells↗
PubMed2001

Transcriptional silencing of Cyclooxygenase-2 by hyper-methylation of the 5' CpG island in human gastric carcinoma cells.

It has been well established that overexpression of Cyclooxygenase-2 (Cox-2) in epithelial cells inhibits apoptosis and increases the invasiveness of malignant cells, favoring tumorigenesis and metastasis. However, the molecular mechanism that regulates Cox-2 expression has not been well defined in gastric carcinoma. In this study, we examined whether the Cox-2 expression could be regulated by hyper-methylation of the Cox-2 CpG island (spanning from -590 to +186 with respect to the transcription initiation site) in human gastric carcinoma cell lines. By Southern analysis, we found that three gastric cells (SNU-601, -620, and -719) without Cox-2 expression demonstrated hyper-methylation at the Cox-2 CpG island. A detailed methylation pattern using bisulfite sequencing analysis revealed that all of the CpG sites were completely methylated in SNU-601. Treatment with demethylating agents effectively reactivated the expression of Cox-2 and restored IL-1beta sensitivity in the previously resistant SNU-601. By transient transfection experiments, we demonstrate that constitutively active Cox-2 promoter activities were exhibited even without an exogenous stimulation in SNU-601. Furthermore, when the motif of the nuclear factor for interleukin-6 expression site, the cyclic AMP response element, or both was subjected to point mutation, the constitutive luciferase activity was markedly reduced. In addition, Cox-2 promoter activity was completely blocked by in vitro methylation of all of the CpG sites in the Cox-2 promoter region with SssI (CpG) methylase in SNU-601. Taken together, these results indicate that transcriptional repression of Cox-2 is caused by hyper-methylation of the Cox-2 CpG island in gastric carcinoma cell lines.

Azacitidine↗
PubMed2001

Expression and characterization of a recombinant Fab fragment derived from an anti-human alpha-fetoprotein monoclonal antibody.

Alpha-fetoprotein (AFP) is a well-known molecular marker indicating the development of cancer as well as fetal abnormalities such as open neural tube defects. Accordingly the measurement of serum AFP is important for the diagnosis of hepatocellular carcinoma (HCC) and other abnormalities. Monoclonal antibodies (McAb) to AFP were produced to develop an immunoassay kit, and to study the possibility of an antibody (Ab) therapy. The immunoglobulin genes were cloned from hybridoma cells, and expressed in E. coli as an Fab soluble into a culture medium. The Fab of anti-AFP McAb exhibited binding to AFP and similar affinity compared to the original IgG. This recombinant antibody can be studied further for in vivo imaging and immunotherapeutics.

Amino Acid Sequence↗
PubMed2001

Study on mechanism of multistep hepatotumorigenesis in rat: development of hepatotumorigenesis.

With the aim of establishing bio-indices for the development of multistep hepatotumorigenesis, rats were fed water containing 0.01% diethylnitrosamine (DEN) ad libitum for 13 weeks. This treatment with DEN only made it possible to induce hepatic tumors in 100%. After the DEN administration, several clinical symptoms were observed including minor behavioral changes, brittleness of hair and a decrease in water and food intake. The concentration of total serum protein and albumin in all treated groups was significantly lower than in non-treated controls (P<0.05). Increase of specific enzyme (AST, ALT and GGT) activity (P<0.05), variable tumor size and hepatomegaly of the liver was observed in all rats treated with DEN for 10 weeks. Both hepatocellular carcinoma and cholangiocarcinoma were found in the same livers at the same time, and were prominently developed after 12 weeks. In case of carcinoma, some of the livers showed more or less advanced states over the 12-15 weeks period. In the present study, hepatocellular carcinoma was developed by treating DEN in only the drinking water, without any other carcinogens or without partial hepatectomy. These results indicate that DEN is a new carcinogen that acts directly on it the liver, moreover, it might be very useful for investigating hepatotumorigenesis.

Alanine Transaminase↗
PubMed2000

Amorpha-4,11-diene synthase of Artemisia annua: cDNA isolation and bacterial expression of a terpene synthase involved in artemisinin biosynthesis.

Artemisia annua, an indigenous plant to Korea, contains an antimalarial sesquiterpene, artemisinin. The first committed step of artemisinin biosynthesis is the cyclization of farnesyl diphosphate by a sesquiterpene synthase to produce an amorphane-type ring system. The aims of this research were to molecularly clone and express amorpha-4,11-diene synthase for metabolic engineering. PCR amplification of genomic DNA with a pair of primers, designed from the conserved regions of sesquiterpene synthases of several plants, produced a 184-bp DNA fragment. This fragment was used in Northern blot analysis as a probe, showing approximately 2.2 kb of a single band. Its sequence information was used to produce 2106 bp of a full-length cDNA sequence including 1641 bp of open reading frame for 546 amino acids (kcs12) through a rapid amplification of cDNA ends (RACE). The deduced amino acid sequence displayed 36% identity with 5-epi-aristolochene synthase of Nicotiana tabacum. A soluble fraction of Escherichia coli harboring kcs12 catalyzed the cyclization of farnesyl diphosphate to produce a sesquiterpene, which was identified through GC-MS analysis as amorpha-4,11-diene.

Alkyl and Aryl Transferases↗
PubMed2000

Lysozyme microencapsulation within biodegradable PLGA microspheres: urea effect on protein release and stability.

Lysozyme was encapsulated within biodegradable poly(D, L-lactide-co-glycolide) microspheres by a double emulsion solvent evaporation method for studying its release mechanism associated with protein stability problems. When urea, a protein unfolding agent, was added into the incubation medium lysozyme release rate from the microspheres increased with the increase in urea concentration. The enhanced lysozyme release was attributed to the suppression of protein aggregation, to the facilitated diffusion of unfolded lysozyme by an efficient reptile motion of unfolded protein molecules through porous channels in microspheres, and to the largely decreased extent of nonspecific protein adsorption onto the enlarged surface area of degrading polymer microspheres in the presence of urea. Encapsulating lysozyme in an unfolded form within PLGA microspheres was attempted by using urea as an excipient. This new urea-based formulation exhibited a more sustained lysozyme release profile than the control formulation, and released lysozyme from the microspheres showed a much less amount of lysozyme dimer population while maintaining a correct conformation after refolding in the incubation medium. This study provides new insights for the formulation of protein encapsulated PLGA microspheres.

Animals↗
PubMed2000

Methylation of specific CpG sites in the promoter region could significantly down-regulate p16(INK4a) expression in gastric adenocarcinoma.

Silencing of p16(INK4a) by methylation of the CpG islands in the promoter region has been found to be an alternative mechanism of inactivation in several tumors. However, in gastric carcinoma, the relationship between methylation status and the transcriptional silencing of the p16 gene remains to be clarified. In this study, we investigated whether methylation of a few specific CpG sites in the promoter region could significantly down-regulate p16 activity in the tumorigenesis of gastric carcinoma. By Southern analysis and bisulfite-modified genomic sequencing of 9 gastric-carcinoma cell lines, we found that the 5 cell lines (55.5%) not expressing p16 mRNA had methylated CpG sites at the promoter region of p16. In addition, we analyzed the p16-protein expression of 28 primary gastric carcinomas and their normal counterparts by immunohistochemical staining (IHC) on paraffin sections. Loss of p16 expression was detected in 6 cases (22%). In 5 out of these 6 (83%), the actual p16 gene was inactivated by de novo methylation of the promoter sites. Taken together, these results suggest a strong correlation between de novo methylation of a few specific CpG sites and transcriptional silencing of the p16 gene in gastric carcinoma.

Adenocarcinoma↗
PubMed2000

Role of paxillin in metabolic oxidative stress-induced cytoskeletal reorganization: involvement of SAPK signal transduction pathway and PTP-PEST gene expression.

Previous studies have shown that glucose deprivation-induced cell death is associated with apoptosis, which is characterized by cellular membrane blebbing in multi-drug-resistant human breast carcinoma MCF-7/ADR cells. In this study, we investigated the mechanism of glucose deprivation-induced cytoskeletal reorganization, which is known to be responsible for the morphological alterations. An increase in the formation of focal adhesion and stress fibers was observed during the early period of glucose deprivation (1-2 h). However, a disappearance of focal adhesion complexes and a loss of stress fiber formation along with membrane blebbing were observed when glucose deprivation continued. These alterations were delayed in MCF-7/ADR cells transfected with bcl-2 and completely suppressed by treatment with an antioxidant, N-acetyl-L-cysteine. These results indicated that glucose deprivation-induced oxidative stress caused the cytoskeletal reorganization. The glucose deprivation-induced alteration of cytoskeletal organization was further investigated by studying a modification of paxillin, one of the focal adhesion proteins. Immunoblotting with anti-paxillin antibody showed that the paxillin band shifted from 68 kDa to about 80 kDa during 1-4 h of glucose deprivation. The mobility shift indicated the modification of paxillin. This possibility was further studied by an immunoprecipitation assay with anti-paxillin/anti-phosphotyrosine antibody and phosphoamino acid analysis (PAA). The immunoprecipitation study revealed that the level of tyrosine phosphorylation of paxillin was maintained for 2 h and then markedly decreased without a change in the total level of paxillin. The PAA study showed that paxillin is dephosphorylated on tyrosine concurrent with phosphorylation on serine/threonine. Expression of a dominant-negative mutant of c-Jun NH(2)-terminal kinase (JNK1) suppressed glucose deprivation-induced JNK1 activation, PTP-PEST gene expression, and alteration of paxillin. Taken together, these results suggest that the alteration of the phosphorylation/dephosphorylation of paxillin may be related to the cytoskeletal reorganization and these events are mediated by glucose deprivation-induced oxidative stress and the stress-activated protein kinase signal transduction pathway.

Acetylcysteine↗
PubMed2000

Effects of solvent selection and fabrication method on the characteristics of biodegradable poly(lactide-co-glycolide) microspheres containing ovalbumin.

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20% were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.

Lactic Acid↗
PubMed2000

Bilateral optic atrophy following diabetic ketoacidosis.

Diabetic ketoacidosis (DKA) can result in neuropathic abnormalities of the somatic and the autonomous nervous systems. We report the case of a 50-year-old man with Type 1 diabetes of 20-year duration who after severe DKA lost vision in his right eye and only retain partial vision in his left. This case demonstrates that optic neural tissue is vulnerable to haemodynamic and metabolic complications of DKA.

Dehydration↗
PubMed2000

Direct measurement of pulsatile insulin secretion from the portal vein in human subjects.

Insulin is secreted in a high frequency pulsatile manner. These pulses are delivered directly into the portal vein and then undergo extraction and dilution before delivery into the systemic circulation. The reported frequency of these insulin pulses estimated in peripheral blood varies from an interpulse interval of 4-20 min. We postulated that this discrepancy is due to the attenuation of the pulse signal in the systemic circulation vs. the portal circulation. In the present study we measured pulsatile insulin release directly in the portal circulation of human subjects who had indwelling transjugular intrahepatic portasystemic stent shunts (TIPSS) to decompress portal hypertension. We quantitated pulsatile insulin secretion in both the overnight fasted state (fasting) and during a hyperglycemic clamp (8 mmol/L). Direct portal vein sampling established that pulsatile insulin secretion in humans has an interval (periodicity) of approximately 5 min. The amplitude (and mass) of the insulin concentration oscillations observed in the portal vein was approximately 5-fold greater than that observed in the arterialized vein and was similar to that observed in the dog. Increased insulin release during hyperglycemia was achieved through amplification of the insulin pulse mass. In conclusion, direct portal vein sampling in humans revealed that the interpulse interval of insulin pulses in humans is about 5 min, and this frequency is also observed when sampling from the systemic circulation using a highly specific insulin assay and 1-min sampling, but is about 4-fold greater than the frequency observed at this site using single site RIAs. We confirm that enhanced insulin release in response to hyperglycemia is achieved by amplification of these high frequency pulses.

Adult↗
PubMed2000

Chronological effects of atherogenic diets on the aorta, liver and spleen of rabbits.

To investigate the temporal progression of atherogenesis on the aorta and involvement of the monocyte-macrophage system in the liver and spleen, we fed 74 rabbits with high fat (14 or 7 gm%) and cholesterol (2 and 1%) diets for 4 to over 24 weeks. Using both light and electron microscopies, we found that the fibro-fatty areas on the luminal surface of aortas was spread over along the feeding time dependently. The fat deposits also in the liver and spleen worsened depending on the time of feeding the atherogenic diets. Not only monocyte-derived foam cells, but also parenchymatous cells in the liver and spleen involved become fat-laden cells. According to these results, we propose that there are three stages: 1) the primary seeding, 2) the intermediate maturing and 3) the advanced periods. These periods may play very important roles in designing the management and treatment of atherosclerotic patients.

Animals↗
PubMed2000

The disappeared disease: tuberculosis of the nasal septum.

Recent advances in chemotherapy have reduced the incidence of upper respiratory tract tuberculosis. Tuberculosis of the nose is mainly by secondary infection to pulmonary tuberculosis via contagious, hematogenous or lymphatic routes. Primary infection of the nose is rare but possible when self-cleansing mechanism and lysosomal activity, of the nose is lost. A 45-year-old Korean woman with the chief complaints of nasal obstruction, crusting, and recurrent episodes of epistaxis is presented. Physical examination of the nose revealed friable, easily bleeding masses with crusts on both sides of the septum. The appearance and consistency of the lesions were different from those of nasal polyps. Chest and sinu X-rays revealed no active lesions. Tuberculin skin test was positive and the biopsied specimen proved to be consistent with tuberculosis. Her condition improved after anti-tuberculous medication for about 6 months.

Antitubercular Agents↗
PubMed1999

Up-regulation of human telomerase catalytic subunit during gastric carcinogenesis.

BACKGROUND: Telomerase activation is thought to be essential for the stabilization of telomere length, through which immortalization and oncogenesis are achieved, but little is known about the regulation of telomerase in human gastric carcinoma cells. METHODS: A total of 27 primary gastric tumors, 29 cases of intestinal metaplasia, and 30 cases of normal mucosa, as well as 8 gastric carcinoma cell lines, were examined for the relation between telomerase activation and gastric carcinogenesis. Telomerase activity was detected by telomeric repeat amplification protocol, and the expression of each telomerase subunit was evaluated by Northern blot analysis or reverse transcriptase--polymerase chain reaction. RESULTS: Telomerase activity was found in all 8 gastric carcinoma cell lines and in 25 of 27 gastric carcinoma tissue samples (93%), and weakly observed in 11 of 29 gastric intestinal metaplasia samples (38%). None of 30 normal gastric tissue samples displayed telomerase activity. The mRNA expression of human telomerase catalytic subunit (hTERT) was up-regulated in 26 of 26 tumor tissue samples (100%) and in 19 of 24 intestinal metaplasia (79%) in which telomerase activity was weak or negative. Normal gastric mucosa expressed the telomerase gene, albeit at low levels. In contrast to hTERT, human telomerase RNA component and human telomerase-associated protein expression did not parallel telomerase activity, which was independent of tumor stage and histology. CONCLUSIONS: hTERT expression is up-regulated during an early stage in the carcinogenic process, and telomerase activation may be a critical step in gastric carcinogenesis.

Adult↗
PubMed1999

The nuclei innervating digastric muscle do not project to the hypoglossal nucleus in the rat.

We employed the retrograde neural tracing method using the pseudorabies virus bartha strain (PRV-Ba) to investigate the projection from accessory trigeminal nucleus (Acc5) or accessary facial nucleus (Acc7) to hypoglossal nucleus (HP). After injection of PRV-Ba into the bellies of the digastric muscle, the PRV-Ba containing neurones were observed in Acc5 of the cranial belly injected rats and Acc7 of caudal belly injected rats ipsilaterally, but not in HP. These results suggest that Acc5 and Acc7 may not project to HP and that movements of the digastric muscle are not related to cooperation with tongue movements during mastication.

Animals↗
PubMed1999

The coexistence of calcitonin gene-related peptide and substance P in pericellular arborization and satellite cell of goat trigeminal and nodose ganglia.

Pericellular arborization is reported to be the self-regulating structure in sensory ganglia. Although the calcitonin gene-related peptide (CGRP) or substance P (SP) immunoreactive pericellular arborization appeared in the sensory ganglia, there was no available information that CGRP and SP colocalize in this structure. As the attempts to resolve the question described above, the present study was undertaken to identify the coexistence of CGRP and SP in pericellular arborizations of the goat nodose and trigeminal ganglia by double immunohistochemistry. As the results show, CGRP immunoreactivity was present in every pericellular arborization containing SP immunoreactivity in trigeminal ganglia, however, pericellular network containing CGRP or SP immunoreactivity was not present in nodose ganglia. Unexpectedly, a few small satellite elements were observed to contain intense CGRP and SP immunoreactivity at the periphery of CGRP and SP immunoreactive neurones in nodose ganglia. Therefore, these results suggest that CGRP and SP coexist in pericellular arborizations, and that satellite cell as well as pericellular arborization may be involved in intraganglionic regulation of goat sensory ganglia.

Animals↗