Helmut Zarbl

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We have found that under appropriate conditions, an allele-specific polymerase chain reaction (PCR) can achieve a sensitivity suitable for measuring specific, infrequent mutations in single cell systems or in animal tissues. Using the 12th codon GC-to-AT mutation in the rat c-Ha-ras gene as a model system, we have defined conditions that allow for(More)
To facilitate collaborative research efforts between multi-investigator teams using DNA microarrays, we identified sources of error and data variability between laboratories and across microarray platforms, and methods to accommodate this variability. RNA expression data were generated in seven laboratories, which compared two standard RNA samples using 12(More)
Frequently, primary hepatocytes are used as an in vitro model for the liver in vivo. However, the culture conditions reported vary considerably, with associated variability in performance. In this study, we characterized the differentiation character of primary human hepatocytes cultured using a highly defined, serum-free two-dimensional sandwich system,(More)
Over the last two decades, the incidence of esophageal adenocarcinoma (EA) has increased dramatically in the US and Western Europe. It has been shown that EAs evolve from premalignant Barrett's esophagus (BE) tissue by a process of clonal expansion and evolution. However, the molecular phenotype of the premalignant metaplasia, and its relationship to those(More)
The fte-1 gene, previously cloned in our laboratory as a putative v-fos transformation effector gene (C.J. Kho and H. Zarbl, Proc. Natl. Acad. Sci. USA, 89: 2200-2204, 1992), has been shown to encode ribosomal protein S3a. Comparison of fte-1 expression in a variety of normal and transformed cells indicated that elevated expression of fte-1 mRNA was(More)
Induction of mammary carcinomas in rats by a single exposure to a carcinogen during sexual development often involves malignant activation of the Ha-ras-1 locus. Each of the Ha-ras-1 oncogenes present in tumours induced by N-nitroso-N-methylurea, but not in those induced by 7,12-dimethylbenz(a)anthracene, became activated by the same G----A transition, the(More)
Previously, we demonstrated that primary cultures of rat hepatocytes evidence higher levels of differentiated function when cultured in the presence of a dilute overlay of extracellular matrix (Matrigel). In this investigation, we used DNA microarrays, quantitative RT-PCR, immunoblotting, and cell morphology analyses to evaluate the biological responses(More)
Some single-nucleotide polymorphisms (SNPs) increase the risk of mortal disease. Identifying these SNPs and the genes in which they reside is an important area in human genomics. Such qualitative observations are important in themselves. However, an accurate assessment of the numerical distribution and age-dependent decline of SNPs in the population would(More)
In the present study we identified a positive transcriptional element within the rat Ha-ras promoter previously known as Ha-ras response element (HRE) and identified a trans-acting factor that binds HRE sequences in rat mammary cells. To identify the binding protein we employed sequence specific DNA affinity chromatography. Amino acid sequence analysis of(More)