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M Hawn

Publications and source records attributed to M Hawn.

4 recordsLinked to original sources
PubMed1995

In vitro transcription/translation assay for the screening of hMLH1 and hMSH2 mutations in familial colon cancer.

BACKGROUND & AIMS: Hereditary nonpolyposis colorectal cancer (HNPCC) has been linked recently to a defect in repairing mismatched nucleotides in DNA. The aim of this study was to screen for germline mutations that result in prematurely truncated proteins in two of the mismatch repair genes identified at this time, hMLH1 and hMSH2, in a consecutive series of patients belonging to familial aggregations of colorectal cancer. METHODS: Nineteen individuals with colorectal cancer from 19 families were consecutively referred because of a strong positive family history of colorectal cancer. Premature truncation mutations in hMLH1 and hMSH2 were sought from lymphocyte RNA by using an in vitro transcription/translation (IVTT) assay. RESULTS: Protein truncating mutations in the hMLH1 or hMSH2 genes were found in 50% of families with HNPCC (6 of 12) but were not observed in any of the remaining familial aggregations that did not fulfill the standard criteria for HNPCC. In some of the IVTT-positive samples, the mutations were characterized by genomic sequencing. CONCLUSIONS: IVTT may be a practical method to accomplish primary screening of germline mutations in DNA mismatch pair genes in HNPCC; however, a broader approach is necessary to obtain a more complete picture of the mutational spectrum in HNPCC and other familial aggregations of colorectal cancer.

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PubMed1989

Carbonic anhydrase II gene expression in isolated canine gastric parietal cells.

The participation of carbonic anhydrase (CA II) in the gastric acid secretory process has been the subject of considerable controversy. We utilized a cDNA probe for CA II to measure CA II gene expression in canine gastric parietal cells that had been stimulated with the three principal acid secretagogues, carbachol, gastrin, and histamine. Hybridization to dot blots of total parietal cell RNA showed a significant increase in specific CA II mRNA content within minutes of secretagogue addition: carbachol stimulation led to an increase of 52 +/- 8.9%, reaching a maximum within 20 min; gastrin stimulation led to an increase within 60 min of 104 +/- 10.6%; stimulation with histamine was followed within 20 min by an increase of 30 +/- 7.2%. We also measured transcription rates for the CA II gene in cells stimulated by each agent and found an increase within 15 min. Our results show that CA II gene expression is regulated by agents that stimulate the parietal cell to secrete acid and that the accumulation of CA II mRNA subsequent to the initial interaction of stimulant appears to result from new transcription of the CA II gene. These data suggest the participation of CA II in the acid secretory response of the parietal cell to secretagogues.

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