Magnetic Separations in Microbiology Cell Biology Medicine and Parasitology

IMS and, in some cases, lectin-magnetic separations are often used in the above-mentioned disciplines. In microbiology they are especially used for the detection of pathogenic microorganisms. IMS enables the time necessary for detection of the target pathogen to be shortened. Target cells are magnetically separated directly from the sample or the pre-enrichment medium. Isolated cells can than be identified by standard, specific microbiological procedures. IMS is not only faster but also usually gives a higher number of positive samples. Also sublethally injured and stressed microbial cells can be very efficiently isolated using IMS. The most important microbial pathogens can be detected using commercially available specific im-munomagnetic particles; they are used for the detection of Salmonella, Listeria and Escherichia coli O157. New immunomagnetic particles for the detection of other microbial pathogens are under development.

Removal of cancer cells is one of the most important applications of IMS in the area of cell biology and medicine. The first experiments were performed in the 1970s and since then an enormous number of applications have been described. Cancer cells are usually removed from bone marrow prior to its autologous transplantation and using IMS they are detected in blood. Elimination of graft-versus-host disease (GvHD) in allogenic bone marrow transplan tation requires an effective removal of T cells from the bone marrow of the donor. A direct method enabled a 103 times depletion of T cells.

Magnetic particles are being increasingly used for isolation of human cell subsets directly from blood and other cell sources. B lymphocytes, endothelial cells, granulocytes, haematopoietic progenitor cells, Langerhans cells, leukocytes, monocytes, natural killer cells, reticulocytes, T lymphocytes, spermatozoa and many others may serve as examples. Cells from other animal and plant species have been successfully separated, too.

Not only whole cells, but also cell organelles can be isolated from crude cellular fractions. Dynal (Oslo, Norway) has developed Dynabeads M-500 Subcellu-lar, which are able to isolate rapidly more than 99% of target organelles.

In the area of parasitology Cryptosporidium and Giardia are the parasites where IMS is of interest. Two commercially available kits can be used for this purpose. Both products are used in the method 1622: Cryptosporidium in Water by Filtration/IMS/FA (December 1997 Draft) of the US Environmental Protection Agency. In very low turbidity samples (clean waters), IMS has demonstrated significantly better results than the standard procedures. When water samples were turbid, the recovery efficiency of IMS diminished.

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Solar Panel Basics

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