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Sung Jin Cho

Publications and source records attributed to Sung Jin Cho.

At least 19 recordsLinked to original sources
PubMed2006

A facile one-pot preparation of alkyl aminoaryl sulfides for the synthesis of GW7647 as an agonist of peroxisome proliferator-activated receptor alpha.

We have developed two simple and high yielding one-pot syntheses of alkyl aminoaryl sulfides containing a series of four-steps: in situ protection of the free amine by reaction with a Grignard reagent, halogen-lithium exchange, sulfur insertion, and a substitution reaction with various electrophiles. Through this protocol, we have successfully synthesized tert-butyl-2-[4-(2-aminoethyl)phenylsulfanyl]-2-methylpropanoate, a key intermediate for the synthesis of GW7647 and GW9578 (ureido-TiBAs), in 92% yield. Furthermore, we were able to improve the overall yield of GW7647 to 66%, 3 times the yield previously reported.

Amines↗
PubMed2006

ADAAPT: Amgen's data access, analysis, and prediction tools.

The Amgen's Data Access Analysis Prediction Tools (ADAAPT) system is a desktop decision support tool developed to provide flexible access and analysis of chemical and biological data. The system is platform independent, adaptable, easily deployed, and scalable. It consists of four main modules: access, analysis, prediction, and tools. The access module contains numerous user interfaces designed to retrieve data easily. The analysis module provides standard computational tools to perform property calculation, QSAR/QSPR, and statistical analyses. The prediction module contains in-house models to calculate a drug-likeness score and absorption index. Finally, the tools module provides a wide array of features that are of general interest to our scientists.

Computer Systems↗
PubMed2006

N-Benzylbenzamides: a new class of potent tyrosinase inhibitors.

A series of potent inhibitors of tyrosinase and their structure-activity relationships are described. N-Benzylbenzamide derivatives (1-21) with hydroxyl(s) were synthesized and tested for their tyrosinase inhibitory activity. With this series, compound 15 provided a potent tyrosinase inhibition: it effectively inhibited the oxidation of l-DOPA catalyzed by mushroom tyrosinase with an IC(50) of 2.2microM.

Benzamides↗
PubMed2006

Who are susceptible to pseudomembranous colitis among patients with presumed antibiotic-associated diarrhea?

PURPOSE: Pseudomembranous colitis is a severe form of antibiotic-associated diarrhea. However, there have been no reports about the factors that make patients with presumed antibiotic-associated diarrhea susceptible to pseudomembranous colitis. This study was designed to determine the clinical risk factors for pseudomembranous colitis among the patients with presumed antibiotic-associated diarrhea. METHODS: This was a retrospective study of 150 consecutive patients admitted to our institution between January 2000 and December 2004 with a diagnosis of presumed antibiotic-associated diarrhea. All patients underwent sigmoidoscopy or colonoscopy because of diarrhea after administration of antibiotics. Pseudomembranous colitis was confirmed both endoscopically and histologically. Various clinical parameters were compared between the pseudomembranous colitis group and non-pseudomembranous colitis group. RESULTS: The mean age of patients was 61 years, and 60 percent (90/150) was female. Pseudomembranous colitis was diagnosed in 53 percent (80/150). On univariate analysis, older than aged 70 years (P = 0.014), antibiotic therapy for more than 15 days (P < 0.0001), hospital stay for more than 20 days (P < 0.0001), number of antibiotics used more than one (P = 0.01), and surgical procedures (P = 0.029) were significant parameters for pseudomembranous colitis. On multivariate analysis, the important clinical risk factors were advanced age (older than aged 70 years; adjusted odds ratio, 2.7; 95 percent confidence interval, 1.208-6.131; P < 0.016) and long hospital stay (more than 20 days; adjusted odds ratio, 5.1; 95 percent confidence interval, 2.1-12.259; P < 0.0001). When both risk factors were present, the positive predictive value of pseudomembranous colitis was 0.86. CONCLUSIONS: Advanced age and long hospital stay may make patients with presumed antibiotic-associated diarrhea susceptible to pseudomembranous colitis. Therefore, pseudomembranous colitis should be first suspected in cases with presumed antibiotic-associated diarrhea having such risk factors.

Aged↗
PubMed2006

[Frequency of loss of heterozygosity on chromosome 17 in intrahepatic cholangiocarcinoma].

UNLABELLED: BACKGROUNDS/AIM: Intrahepatic cholangiocarcinoma is the second most common intrahepatic neoplasm. Carcinogenesis is believed to be a multistage process that occurs as a result of mutations in oncogenes and tumor suppressor genes. Loss of heterozygosity (LOH) is the phenotype of genetic instability which has been used as a tool for detecting genetic phenotype alterations. Large number of the molecular alterations have been described in human cancer. Among them, that of p53 is quite common. The aim of this study was to determine the frequency of LOH at chromosome 17p related with p53. METHODS: Twenty cases who underwent hepatic resection due to intrahepatic cholangiocarcinoma, were included. LOH was analysed with four microsatellite markers by PCR. For the clinicopathologic parameters, tumor size, differentiation, and metastasis were evaluated. RESULTS: Fifteen patients (75%) showed LOH at one of the loci at the least. Five patients were LOH-high and 10 were LOH-low. The highest frequency of LOH was observed at D17S5 by 38.9%. Those of TP53, D17S796 and D17S513 were 29.4%, 21.4% and 35.3%, respectively. In addition, LOH tended to be more frequent when the tumor is mass forming type, poorly differentiated, or has tumor emboli or vascular invasion. CONCLUSIONS: This study showed that LOH was positive in 75% on chromosome 17p in intrahepatic cholangiocarcinoma which was relatively frequent at D17S5.

Aged↗
PubMed2005

Nuclear factor-kappaB activation correlates with better prognosis and Akt activation in human gastric cancer.

PURPOSE: Because the biological significance of constitutive nuclear factor-kappaB (NF-kappaB) activation in human gastric cancer is unclear, we undertook this study to clarify the regulatory mechanism of NF-kappaB activation and its clinical significance. EXPERIMENTAL DESIGN: Immunohistochemistry for NF-kappaB/RelA was done on 290 human gastric carcinoma specimens placed on tissue array slides. The correlations between NF-kappaB activation and clinicopathologic features, prognosis, Akt activation, tumor suppressor gene expression, or Bcl-2 expression were analyzed. We also did luciferase reporter assay, Western blot analysis, and reverse transcription-PCR using the SNU-216 human gastric cancer cell line transduced with retroviral vectors containing constitutively active Akt or the NF-kappaB repressor mutant of IkappaBalpha. RESULTS: Nuclear expression of RelA was found in 18% of the gastric carcinomas and was higher in early-stage pathologic tumor-node-metastasis (P = 0.019). A negative correlation was observed between NF-kappaB activation and lymphatic invasion (P = 0.034) and a positive correlation between NF-kappaB activation and overall survival rate of gastric cancer patients (P = 0.0228). In addition, NF-kappaB activation was positively correlated with pAkt (P = 0.047), p16 (P = 0.004), adenomatous polyposis coli (P < 0.001), Smad4 (P = 0.002), and kangai 1 (P < 0.001) expression. An in vitro study showed that NF-kappaB activity in gastric cancer cells is controlled by and controls Akt. CONCLUSIONS: NF-kappaB activation was frequently observed in early-stage gastric carcinoma and was significantly correlated with better prognosis and Akt activation. These findings suggest that NF-kappaB activation is a valuable prognostic variable in gastric carcinoma.

Adolescent↗
PubMed2005

Transcriptome analysis in the midgut of the earthworm (Eisenia andrei) using expressed sequence tags.

In order to gain insight into the expression profiles of the earthworm midgut, we analyzed 1106 expressed sequence tags (ESTs) derived from the earthworm midgut cDNA library. Among the 1106 ESTs analyzed, 557 (50.4%) ESTs showed significant similarity to known genes and represented 229 unique genes of which 166 ESTs were singletons and 63 ESTs manifest as two or more ESTs. While 552 ESTs (49.9%) were sequenced only once, 230 ESTs (20.8%) appeared two to five times and 324 ESTs (29.3%) were sequenced more than five times. Considering this redundancy of expression, it is likely that the gene expression profile of the earthworm midgut would be polarized. The expression of globin-related proteins, including ferritin and linker chain, and fibrinolytic enzymes appeared to account for 10.1% and 4.7% of the total ESTs analyzed in this study, respectively. This suggests that the prime functions of the midgut in the earthworm would be associated with protein hydrolysis as well as globin formation. Among the recognized protein-coding genes, the gene category involved in protein synthesis appeared to be the largest one accounting for 15.6% of the expression in the midgut, followed by gene categories associated with energy (11.2%), homeostasis (10.8%), metabolism (3.6%), cytoskeleton (2.5%), and protein fate (1.4%). With regard to functional aspects, the most abundantly expressed genes were associated with respiratory pigment (10.1%), cellular respiration (8.6%), and fibrin hydrolysis (4.7%). In addition, we were able to identify novel ESTs in the earthworm, which were related to the innate immune system, including destabilase, a possible antagonist of transglutaminase.

Animals↗
PubMed2004

Anticancer activity of 3-O-acyl and alkyl-(-)-epicatechin derivatives.

By changing the structure or replacing the gallate group of (-)-ECG, 3-O-acyl and alkyl-(-)-epicatechin derivatives were synthesized to be screen as anticancer agents using the MTT assay in vitro against cancer cell lines (PC3, SKOV3, U373MG). 3-O-Acyl and alkyl-(-)-epicatechin derivatives (4-25) exhibited better anticancer activity than (-)-ECG and specially, compounds 6-8, 17-19, which were modified aliphatic chains with moderate sizes (C8-C12) showed strong anticancer activity (IC50=6.4-31.2 microM). The introduction of an alkyloxy group on 3-O-hydroxyl instead of an acyloxy group significantly enhanced inhibitory activity. Consequently, the compound that showed the most potency as anticancer agents were 3-O-decyl-(-)-epicatechin (18) (IC50=8.9, 7.9, 6.4 microM against PC3, SKOV3, U373MG, respectively), which modified the appropriate lipophilic group on the C-3 hydroxyl as an alkyloxy group.

Antineoplastic Agents↗
PubMed2004

Osteosarcoma of the ethmoid sinus.

A rare case of chondroblastic osteosarcoma arising from the ethmoid sinus is reported. The patient, a 34-year-old woman, presented with diminished visual acuity of the left eye. CT and MR imaging showed a heterogeneous left-sided nasoethmoidal mass destroying the medial orbital wall. Biopsy revealed a chondroblastic osteosarcoma containing malignant chondroid elements and calcified malignant osteoid. Treatment consisted of craniofacial resection followed by radiotherapy and chemotherapy with symptomatic improvement. We briefly discuss ethmoidal osteosarcomas.

Adult↗
PubMed2004

Antimicrobial activity of 3-O-acyl-(-)-epicatechin and 3-O-acyl-(+)-catechin derivatives.

As an exploratory investigation of antimicrobial promoting compounds, 3- O-acyl-(-)-epicatechins and 3- O-acyl-(+)-catechins possessing various aromatic groups and aliphatic chains of varying length from C4 to C16 for increasing lipophilicity were synthesized and tested for antimicrobial activities against Gram-positive, Gram-negative bacteria and fungi. The (-)-epicatechin and (+)-catechin derivatives comprised of aromatic groups increased activity and derivatives with acyl chain groups of carbon atoms in the close vicinity of C8 to C10 showed strong antimicrobial activity (MIC = 2 - 8 microg/ml) against Gram-positive bacteria and weak activity against fungi. However, the activity decreased when the carbon chain length of the substituents was too short (C4 to C6) or too long (C16). These results suggest that the presence of lipophilic substituents with moderate sizes might be crucial for the optimal antimicrobial activity.

Anti-Infective Agents↗
PubMed2003

Manganese superoxide dismutase expression correlates with chemosensitivity in human gastric cancer cell lines.

PURPOSE: The purpose is to investigate the potential correlation between antioxidant enzyme (AOE) levels and resistance to anticancer drugs in human gastric carcinoma cell lines. EXPERIMENTAL DESIGN: Protein contents of AOEs such as manganese superoxide dismutase (MnSOD), copper/zinc superoxide dismutase, catalase, glutathione S-transferase-pi, p-glycoprotein, and multidrug resistance-associated protein were observed by Western blot analysis, and MnSOD activity was measured in six Korean gastric cancer cell lines. The direct correlation between AOEs and the chemosensitivity to doxorubicin (DOX), mitomycin C, 5-fluorouracil, and vinblastine was analyzed by cytotoxicity test. MnSOD was overexpressed by transient transfection of human MnSOD cDNA. RESULTS: Expressions of AOEs in gastric cancer cell lines were variable. MnSOD expression was related with the resistance to DOX and mitomycin C but not with that to 5-fluorouracil and vinblastine. In comparison, expressions of other AOEs, p-glycoprotein and multidrug resistance-associated protein, were not correlated with tumor sensitivity to any of the drugs used. Cell lines with a high MnSOD protein content showed higher MnSOD activity than those with a low MnSOD protein content. In addition, MnSOD overexpression increased the resistance of gastric carcinoma cells to DOX. CONCLUSIONS: MnSOD is an important factor of drug response to reactive oxygen species-generating anticancer drugs in the gastric cancer cells. Thus, measurement of MnSOD levels in clinical samples may provide an indication of subsequent treatment response of gastric cancer patients.

Antineoplastic Agents↗
PubMed2003

Hox genes from the earthworm Perionyx excavatus.

The Hox genes of the oligochaete, Perionyx excavatus, were surveyed using PCR and phylogenetic analysis. We were able to identify 11 different Hox gene fragments. Comparative and phylogenetic analyses revealed that this oligochaete would have at least five Hox genes of the anterior group, including three copies of labial-type, five of the central group and one of the posterior group. This is the first report regarding sequence information and phylogenetic analysis of Hox genes in the earthworm.

Animals↗
PubMed2003

Akt/PKB activation in gastric carcinomas correlates with clinicopathologic variables and prognosis.

Akt/protein kinase B (PKB) plays an important role in cell survival. However, the role of Akt in the biology of gastric cancer has not been well studied. We sought to investigate the expression of Akt or phosphorylated Akt (pAkt) in human gastric carcinomas and to analyze the relationship between Akt or pAkt and the clinicopathologic parameters. The expressions of Akt and pAkt were evaluated immunohistochemically in 311 gastric carcinomas using the tissue array method. Akt expression was detected in 74% of the tumors and pAkt expression in 78%. pAkt was highly expressed in the early stage of pTNM (p=0.011). We also found an inverse association between pAkt and lymphatic invasion (p=0.01) or lymph node metastasis (p=0.008). pAkt expression was significantly correlated with a higher survival in patients with stage I carcinomas (p=0.0003). Interestingly, combined evaluation revealed that the group with pAkt-positive and lymph node-negative carcinomas showed a better prognosis than the other groups (p<0.0001). In addition, pAkt was shown to correlate positively with APC (p=0.002) and Smad4 (p<0.0001) expression. These findings suggest that pAkt expression may help to predict the clinical outcome of gastric cancer patients.

Adenomatous Polyposis Coli Protein↗
PubMed2002

Prediction of aqueous solubility of organic compounds using a quantitative structure-property relationship.

A quantitative structure-property relationship (QSPR) was developed for predicting the aqueous solubility of drug-like compounds from their chemical structures. A set of 321 structurally diverse drugs or related compounds, with their intrinsic aqueous solubility collected from literature, was used in this analysis. The data were divided into a training set (n = 267) for building the model and a randomly chosen testing set (n = 54) for assessing the predictive ability of the model. A series of molecular descriptors was calculated directly from chemical structures and a set of eight descriptors, including dipole moment, surface area, volume, molecular weight, number of rotatable bonds/total bonds, number of hydrogen-bond acceptors, number of hydrogen-bond donors and density, was chosen for the final model. The eight-descriptor model generated by multiple linear regression was further optimized by a genetic algorithm guided selection method. The model has a correlation coefficient (r) of 0.95 and a root-mean-square (rms) error of 0.56 log unit. It predicts the solubility of testing set compounds with a reasonable degree of accuracy (r = 0.84 and rms = 0.86 log unit). The present model can serve as a tool for medicinal chemists to guide their early synthetic efforts in arriving at appropriate analogs.

Algorithms↗
PubMed2002

Testing non-additivity of biological activity in a combinatorial library.

Combinatorial chemistry offers new opportunities to generate and analyze QSAR data. Traditional QSAR attempts to correlate activity with structure. With combinatorial chemistry, it is possible to correlate activity directly with the reagents used in a combinatorial library. If one can determine which reagents lead to the compounds of highest activities, it may then be possible to predict active compounds in virtual libraries of 10(6) to 10(10) compounds. This would greatly facilitate library design and provide confidence that the best compounds are being considered for synthesis. An important question is whether the activity of a product molecule can be considered as a sum of its components. This is referred to as additivity between reagents. If there is non-additivity, it is necessary to identify and include the non-additive terms in the model in order to improve QSAR models. Presented here are methods for developing QSAR models relating compound activity to reagents and a method for detecting the second effects of side-chain non-additivity. If the reagents in a library are shown to be additive in their contribution to activity, simple QSAR based on additive models can be applied confidently to reagents. Testing non-additivity can also guide the synthesis of the library. If the contributions are shown to be additive then the strategy for library synthesis may be shifted to include many reagents of a given type but not to make all combinations. The result is more efficient use of resources. In the analysis of percent inhibition data of a combinatorial library an additive model using reagents as descriptors yields a R(2) of 0.43. Application of this method is probably appropriate for HTS single point data while methods employing topological or pharmacophore based descriptors would be necessary to adequately model IC50 data.

Combinatorial Chemistry Techniques↗
PubMedDate not supplied

Genetic Algorithm guided Selection: variable selection and subset selection.

A novel Genetic Algorithm guided Selection method, GAS, has been described. The method utilizes a simple encoding scheme which can represent both compounds and variables used to construct a QSAR/QSPR model. A genetic algorithm is then utilized to simultaneously optimize the encoded variables that include both descriptors and compound subsets. The GAS method generates multiple models each applying to a subset of the compounds. Typically the subsets represent clusters with different chemotypes. Also a procedure based on molecular similarity is presented to determine which model should be applied to a given test set compound. The variable selection method implemented in GAS has been tested and compared using the Selwood data set (n = 31 compounds; v = 53 descriptors). The results showed that the method is comparable to other published methods. The subset selection method implemented in GAS has been first tested using an artificial data set (n = 100 points; v = 1 descriptor) to examine its ability to subset data points and second applied to analyze the XLOGP data set (n = 1831 compounds; v = 126 descriptors). The method is able to correctly identify artificial data points belonging to various subsets. The analysis of the XLOGP data set shows that the subset selection method can be useful in improving a QSAR/QSPR model when the variable selection method fails.

Algorithms↗
PubMedDate not supplied

FLAME: a program to flexibly align molecules.

Herein, we describe a method to flexibly align molecules (FLAME = FLexibly Align MolEcules). FLAME aligns two molecules by first finding maximum common pharmacophores between them using a genetic algorithm. The resulting alignments are then subjected to simultaneous optimizations of their internal energies and an alignment score. The utility of the method in pairwise alignment, multiple molecule flexible alignment, and database searching was examined. For pairwise alignment, two carboxypeptidase ligands (Protein Data Bank codes and ), two estrogen receptor ligands ( and ), and two thrombin ligands ( and ) were used as test sets. Alignments generated by FLAME starting from CONCORD structures compared very well to the X-ray structures (average root-mean-square deviation = 0.36 A) even without further minimization in the presence of the protein. For multiple flexible alignments, five structurally diverse D3 receptor ligands were used as a test set. The FLAME alignment automatically identified three common pharmacophores: a base, a hydrogen-bond acceptor, and a hydrophobe/aromatic ring. The best alignment was then used to search the MDDR database. The search results were compared to the results using atom pair and Daylight fingerprint similarity. A similar database search comparison was also performed using estrogen receptor modulators. In both cases, hits identified by FLAME were structurally more diverse compared to those from the atom pair and Daylight fingerprint methods.

Journal Article↗