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Q K Chen

Publications and source records attributed to Q K Chen.

6 recordsLinked to original sources

PromFD 1.0: a computer program that predicts eukaryotic pol II promoters using strings and IMD matrices.

MOTIVATION: A large number of new DNA sequences with virtually unknown functions are generated as the Human Genome Project progresses. Therefore, it is essential to develop computer algorithms that can predict the functionality of DNA segments according to their primary sequences, including algorithms that can predict promoters. Although several promoter-predicting algorithms are available, they have high false-positive detections and the rate of promoter detection needs to be improved further. RESULTS: In this research, PromFD, a computer program to recognize vertebrate RNA polymerase II promoters, has been developed. Both vertebrate promoters and non-promoter sequences are used in the analysis. The promoters are obtained from the Eukaryotic Promoter Database. Promoters are divided into a training set and a test set. Non-promoter sequences are obtained from the GenBank sequence databank, and are also divided into a training set and a test set. The first step is to search out, among all possible permutations, patterns of strings 5-10 bp long, that are significantly over-represented in the promoter set. The program also searches IMD (Information Matrix Database) matrices that have a significantly higher presence in the promoter set. The results of the searches are stored in the PromFD database, and the program PromFD scores input DNA sequences according to their content of the database entries. PromFD predicts promoters-their locations and the location of potential TATA boxes, if found. The program can detect 71% of promoters in the training set with a false-positive rate of under 1 in every 13,000 bp, and 47% of promoters in the test set with a false-positive rate of under 1 in every 9800 bp. PromFD uses a new approach and its false-positive identification rate is better compared with other available promoter recognition algorithms. The source code for PromFD is in the 'c+2' language.

Algorithms↗

MATRIX SEARCH 1.0: a computer program that scans DNA sequences for transcriptional elements using a database of weight matrices.

The information matrix database (IMD), a database of weight matrices of transcription factor binding sites, is developed. MATRIX SEARCH, a program which can find potential transcription factor binding sites in DNA sequences using the IMD database, is also developed and accompanies the IMD database. MATRIX SEARCH adopts a user interface very similar to that of the SIGNAL SCAN program. MATRIX SEARCH allows the user to search an input sequence with the IMD automatically, to visualize the matrix representations of sites for particular factors, and to retrieve journal citations. The source code for MATRIX SEARCH is in the 'C' language, and the program is available for unix platforms.

Base Sequence↗

[The anti-pancreatic cancer efficacy of LAK cells mediated by YPC3 monoclonal antibody in vitro and in vivo].

The purpose of this study was to investigate a new form of specific targeting immunotherapy for human pancreatic carcinoma. In 4hr 51Cr release assays, the cytolysis of Capan-2 human pancreatic carcinoma cells by LAK cells was enhanced with pancreatic cancer-specific monoclonal antibody (YPC3 McAb). This antibody-dependent cellular cytotoxicity (ADCC) of the LAK cells was more evident while increasing the concentration of YPC3 McAb. The cytotoxic effects of the LAK cells on target cells increased about 60% when 50 micrograms/ml of YPC3 McAb was used. No cytotoxic effect of the LAK cells was found in the presence of irrelevant monoclonal antibody. Experimentally, the growth rate of Capan-2 human pancreatic carcinoma cell line in nude mice was 25%, 100%, and 100% after the injection of LAK cells, splenocytes and YPC3 McAb, respectively. However, simultaneous injection of YPC3 McAb and LAK cells completely inhibited the growth of the cell line. These results suggest that LAK cells in combination with YPC3 McAb might be useful for the treatment of human pancreatic carcinoma.

Animals↗