Biomedical subjects

M U Kopp

Publications and source records attributed to M U Kopp.

4 recordsLinked to original sources

PubMed1998

Chemical amplification: continuous-flow PCR on a chip.

A micromachined chemical amplifier was successfully used to perform the polymerase chain reaction (PCR) in continuous flow at high speed. The device is analogous to an electronic amplifier and relies on the movement of sample through thermostated temperature zones on a glass microchip. Input and output of material (DNA) is continuous, and amplification is independent of input concentration. A 20-cycle PCR amplification of a 176-base pair fragment from the DNA gyrase gene of Neisseria gonorrhoeae was performed at various flow rates, resulting in total reaction times of 90 seconds to 18.7 minutes.

DNA Topoisomerases, Type II↗

PubMed1997

DNA methylation accounts for the inhibition of collagen VI expression in transformed fibroblasts.

The expression of collagen VI, an adhesive glycoprotein of the extracellular matrix, is completely inhibited in virally transformed fibroblasts and in many cell lines derived from spontaneous mesenchymal tumors. Here we present evidence that DNA methylation plays an important role in this inhibition: (a) The mRNA level for DNA methyltransferase is highly increased in simian virus 40 (SV40)-transformed fibroblasts compared with normal cells and this increase correlates with the decrease of the mRNA level for collagen VI. (b) Methylation of the alpha2(VI) collagen promoter in vitro abolishes promoter activity in a transient transfection assay. (c) Genomic sequencing reveals extensive methylation of the promoter region in SV40-transformed cells, but virtually no methylation of the corresponding region in normal cells. Increased methylation is also observed in a rhabdomyosarcoma cell line. (d) Two of the cis-acting elements of the alpha2(VI) collagen promoter lose their affinity for transcription factor AP2 when methylated in vitro as demonstrated by gel retardation experiments. DNA methylation is therefore involved in the silencing of the alpha2(VI) collagen gene. It seems likely that the same mechanism is also responsible for the repression of other transformation-sensitive proteins.

Base Sequence↗

PubMed1997

Developments in technology and applications of microsystems.

In the past year, microchips as applied to miniaturised total analysis systems, or microTAS, have benefited from technological improvements in their fabrication and been applied to analysis in many different biological areas. From a technological perspective, salient work includes fast, cheap and easy micromachining in polymers and integrated optical detection. From the bioapplications perspective, advances in DNA and protein separations, cell manipulations, immunoassays and polymerase chain reaction using on-chip electrophoretic separation stand out.

Chemistry Techniques, Analytical↗

PubMed1995

Down-regulation of collagen XII in transformed mesenchymal cells.

Collagen XII is a complex multidomain protein associated with the surface of interstitial collagen fibrils. This protein is produced in large amounts by fibroblasts cultivated in vitro. However, it is completely absent from cells transformed by the oncogene v-myc or v-src and from cells derived from a methylcholanthrene-induced fibrosarcoma. Since all these cells lack any mRNA for collagen, XII, it seems likely that the synthesis is blocked at the transcriptional level. Experiments with a temperature-sensitive mutant of Rous sarcoma virus demonstrated that a single oncogene product is sufficient to inhibit the synthesis. A reduction in the expression of collagen XII might have profound effects on the stability of the extracellular matrix of transformed cells.

Animals↗