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Biomedical subjects

M Piontek

Publications and source records attributed to M Piontek.

8 recordsLinked to original sources

Heterologous protein production in yeast.

The exploitation of recombinant DNA technology to engineer expression systems for heterologous proteins represented a major task within the field of biotechnology during the last decade. Yeasts attracted the attention of molecular biologists because of properties most favourable for their use as hosts in heterologous protein production. Yeasts follow the general eukaryotic posttranslational modification pattern of expressed polypeptides, exhibit the ability to secrete heterologous proteins and benefit from an established fermentation technology. Aside from the baker's yeast Saccharomyces cerevisiae, an increasing number of alternative non-Saccharomyces yeast species are used as expression systems in basic research and for an industrial application. In the following review a selection from the different yeast systems is described and compared.

Gene Expression

Heterologous gene expression in Hansenula polymorpha: efficient secretion of glucoamylase.

We have introduced the glucoamylase gene (GAM1) from Schwanniomyces occidentalis into the genome of the methylotrophic yeast Hansenula polymorpha to study the potential of this organism as a host for high-level expression of a heterologous gene encoding a secretory protein. Transformants of H. polymorpha containing GAM1 under control of the formate dehydrogenase (FMD) promoter are stable and efficiently secrete an active glucoamylase that is faithfully processed and modified. Yields of up to 1.4g/l of active enzyme were obtained at cell densities of 100-130 grams dry weight per liter.

Amino Acid Sequence

Crohn's disease: what about the pancreas?

Crohn's disease (CD) is now accepted as a systemic illness. The importance of extraintestinal manifestations is underlined by the fact that such "complications" can be more prominent and even more difficult to control than the intestinal disease itself. Lately, evidence for a more than accidental association of pancreatitis and exocrine pancreatic insufficiency with CD is growing. This might have a significant impact on the treatment of abdominal pain and diarrhea in CD, symptoms which have so far been attributed exclusively to the intestinal rather than the extraintestinal manifestations of the disease.

Crohn Disease

Effect of calcium-modifying agents on the growth of human gastric carcinoma cells in vitro.

The antiproliferative effects of various calcium-modifying agents were investigated in human AGS gastric carcinoma cells in culture. Variation of the extracellular calcium concentration, achieved by addition of calcium to the growth medium or binding of calcium to the calcium-chelating agent EDTA, appeared to have little influence on growth of the tumor cells. In contrast, the calcium antagonist verapamil, the calcium ionophore A 23.187 and the calmodulin antagonist W 7, agents supposed to interfere with the regulation of the intracellular calcium concentration, all exerted marked growth inhibiting effects. Our results provide evidence for an important role of intracellular calcium-dependent mechanisms in growth regulation of the human gastric adenocarcinoma cell line AGS.

Calcimycin