Labelling of lymphocytes with various radiosotopes for in vivo tracer studies; a review

Infection risk by dermatophytes during storage and after domestic laundry and their temperature-dependent inactivation

In the developed countries infections of the feet (tinea pedis, athlete's foot) and nails (onychomycosis) with the anthropophile fungus Trichophyton rubrum are most common. We examined the propagation of dermatophytes before and during domestic laundering. About 10% of the infectious material was transferred from contaminated textiles to sterile textiles during storage in a clothes basket simulation indicating a high infection risk during storage. This was evaluated with two quantification techniques: cultivation with subsequent colony counting and tracing of radioactively labelled propagating units. Both approaches reliably revealed similar results with the latter method reducing experimental time to few minutes compared to 2 weeks with the traditional method. The tracer technique allowed favourably to directly reflect the textile-bound infectious material at the moment of skin contact. To address the infection risk during domestic laundry, bioindicators with T. rubrum or the yeast Candida albicans were introduced into common domestic washing procedures with different temperature courses. While C. albicans did not survive any of the tests, T. rubrum could be recovered after washing at 30°C, indicating the risk potential of dermatophyte infections at home. Up to 16% of the initial fungus load was detected in the rinsing water. Washing at 60°C however, eliminated both pathogens, T. rubrum and C. albicans.

Mass spectrometry-based peptide quantification: applications and limitations

In various areas of research, proteomics and particularly the quantification of proteins and peptides renders a useful addition to biochemical experiments. The range of possible applications varies from supervision of concentration changes of relevant proteins during biogenesis to differential proteomics approaches, distinguishing, for instance, healthy and diseased states. Furthermore, mass spectrometry-based peptide quantification yields the possibility of using highly sensitive bottom-up approaches for determination of protein regulations as well as multiplexing capability. Thereby, changes in protein abundances may be linked to specific cellular states bearing the opportunity to reveal marker proteins for several diseases.

Detection of specific anti-hapten antibody-producing hybridoma cells in tissue sections of spleen and liver by hapten-enzyme conjugates using an immunoenzyme approach

A method is presented for the detection of hybridoma cell growth in vivo by making use of the specific antigen (hapten) recognition properties of the produced monoclonal antibodies. Horseradish peroxidase (HRP)-labeled antigen was used for demonstration of intracellular specific antibodies in hybridoma cells. It appeared that intravenously injected anti-penicilloyl-producing hybridoma cells developed mainly in the red pulp of the spleen; to a lesser extent they were found in the liver.

A comparative study of [3H]thymidine and [125I]iodo-2'-deoxyuridine uptake as indicators of in vivo cell proliferation induced by graft-versus-host reaction in the mouse

Since [3H]thymidine ([3H]TdR) and [125I]iododeoxyuridine ([125I]UdR) appear to label very different cell populations in different tissues, we carried out the present investigation to determine the value and limitations of the use of [125I]UdR as a DNA precursor in a study of grafted cell proliferation during the course of a graft-versus-host reaction in mice. Results showed that the iodine radioisotope was as efficient as [3H]thymidine when endogenous thymidylate synthetase was inhibited by fluorodeoxyuridine. The use of 125I as an in vivo labelling compound constitutes a simple technique for evaluating DNA synthesis, provided the unfixed labelled iodine is eliminated by in vitro ethanol washing of tissues. The optimal conditions for elution are defined but may vary from one tissue to another. [125I]UdR and [3H]TdR give similar pictures of the very intricate phenomena accompanying a chronic graft-versus-host reaction (GVHR) induced in mice by minor histoincompatible antigens.

Experimental systems for analysis of the malignant phenotype

Identification of the cellular and subcellular alterations responsible for the metastatic behavior of malignant tumor cells and development of reliable screening programs for detecting new therapeutic agents for improved treatment of metastatic disease both depend crucially on the availability of experimental systems that can serve as relevant models of human cancer. Recent advances in our understanding of the pathogenesis of cancer metastasis have raised serious doubts about the usefulness of many of the experimental approaches that have long been used in the study of metastasis. Recent findings showing that metastases are caused by specific subpopulations of metastatic tumor cells, and that not all cells in a malignant primary tumor possess metastatic properties, are of profound importance for experimental efforts to understand the mechanism of metastatic phenotype among cells from the same tumor means that the traditional, and widely used, approach of analyzing primary tumors and cultured cell lines containing multiple, phenotypically heterogeneous, subpopulations of cells may provide little or no insight into the properties of the metastatic subpopulations, particularly if they represent only a minor fraction of the entire population. Similarly, the practice of screening potential therapeutic modalities for their ability to reduce the mass and/or growth rate of a primary tumor may be inadequate in predicting the responsiveness of metastatic lesions. Solution of these problems requires that new methods must be devised to isolate and characterize the specific subpopulations of tumor cells endowed with metastatic potential. In addition, knowledge of how the extraordinary phenotypic diversity found in tumor cell subpopulations from the same tumor is generated and how subpopulation diversity is regulated during progressive growth of both the primary tumor and its metastases are of fundamental importance if we are to design meaningful experimental systems for studying the metastatic process. This article reviews our current understanding of these complex issues and their implications for the experimental analysis of the malignant phenotype. The merits and shortcomings of different experimental systems are discussed in detail together with the identification of areas in which new experimental strategies and models are now needed.'

The pattern of lymphocytes in the thymus and spleen after labeling with 3H-thymidine and 3H-deoxycytidine

Adult male untreated mice (NMRI) were investigated after radioactive labeling with 3H-thymidine and 3H-deoxycytidine to find out whether the lymphocytes in the cortex and medulla of the thymus as well as in the perifollicular and periarteriolar regions of the spleen show a labeling pattern which allows a classification into T- and B-lymphocytes. The percentages of radioactively labeled small lymphocytes and their mean grain counts were determined. The percentages of radioactively labeled small lymphocytes after 3H-TdR and 3H-CdR showed no significant differences in both splenic zones. The grain counts over the lymphocyte nuclei in the periarteriolar zone showed lower values after 3H-TdR than after 3H-CdR. The lymphocytes in the perifollicular zone were strongly labeled with 3H-TdR and weakly labeled with 3H-CdR. In the thymus medulla, lymphocytes were weakly labeled with 3H-thymidine and strongly labeled with 3H-CdR. In the cortex no significant differences were observed. 75 to 80% of the small lymphocytes in the peripheral blood were weakly and 20-25% strongly labeled after 3H-TdR. Therefore there are similarities in the radioactive labeling pattern of thymic medulla lymphocytes and that of small lymphocytes of the periarteriolar zone of the spleen by both DNA precursors. The small lymphocytes in the peripheral T-dependent tissue zones, for example in the spleen, as well as in the mixed lymphocyte population of the peripheral blood can be differentiated from the B-lymphocytes through the difference in the amount of incorporation of 3H-thymidine and 3H-deoxycytidine.