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Biomedical subjects

H Hülsen

Publications and source records attributed to H Hülsen.

6 recordsLinked to original sources
PubMed2004

Transporting cells with mobile microrobots.

Current research activities on the development of a system for transport and manipulation of biological cells with microrobots are described. If single cells in liquid are to be placed on a grid or sorted by cell type, having a system that can automatically lift, transport and release cells can significantly speed up such a tedious task. Therefore, a system is being developed that can automatically sort different cells by transporting them to different repositories. A method to recognise different types of cells is also being developed. The system consists of several components; a motorised inverted microscope, several different microrobots and a software architecture to control the whole cell manipulation workstation and to provide a user interface.

Journal Article↗
PubMed1989

Influence of carbohydrates on the cytotoxicity of an aqueous mistletoe drug and of purified mistletoe lectins tested on human T-leukemia cells.

Partially and highly purified lectins from Viscum album L. (mistletoe) cause a dose-dependent decrease of viability of human leukemia cell cultures, MOLT-4, after 72 h treatment. The LC50 of the partially purified lectin was 27.8 ng/ml, of the highly purified lectin 1.3 ng/ml. Compared to the highly purified lectin a 140-fold higher protein concentration of an aqueous mistletoe drug was required to obtain similar cytotoxic effects on MOLT-4 cells. Cytotoxicity of the highly purified lectin was preferentially inhibited by D-galactose and lactose, cytotoxicity of the mistletoe drug and the partially purified lectin were preferentially inhibited by lactose and N-acetyl-D-galactosamine (GalNAc). Two lectin fractions with almost the same cytotoxic activity on MOLT-4 cells but with different carbohydrate affinities were isolated by affinity chromatography from the mistletoe drug: mistletoe lectin I with an affinity to D-galactose and GalNAc and mistletoe lectin II with an affinity to GalNAc. The lectin fractions and the mistletoe drug inhibited protein synthesis of MOLT-4 cells stronger than DNA synthesis. Furthermore a subpopulation of MOLT-4, resistant to cytotoxic doses of both the mistletoe drug and the mistletoe lectins, was shown to exhibit a reduced amount of GalNAc and N-acetyl-D-glucosamine in their cellular glycoproteins which are probably responsible for the binding of the cytotoxic lectins. These results indicate that lectins are the main toxins in the mistletoe drug.

Carbohydrates↗
PubMed1986

Differences in the in vitro effectiveness of preparations produced from mistletoes of various host trees.

The in vitro effectiveness of three Helixor preparations produced from mistletoes of different host trees on suspension cell cultures of the human leukemia cell line Molt 4 has been compared by means of dose-response investigations. After 72 h treatment the preparation produced from mistletoes of the appletree (Malus) shows the strongest effect on the growth and viability of the cell cultures. The preparation produced from mistletoes of the fir (Abies) shows also an evident but much weaker effect, whereas the preparation produced from mistletoes of the pine (Pinus) causes a weak effect only at a very high dosage. As shown in 24-h incorporation experiments with 3H-labelled DNA-, RNA- and protein precursors the preparation produced from mistletoes of the apple-tree reduces the protein synthesis of the cells to a greater extent than the DNA-and RNA-synthesis.

Cell Line↗