The nature of Brdička's cancer test

Zusammenfassung Es wird gezeigt, dass die Brdikasche Filtratreaktion durch eine Erhöhung der Konzentration des normalerweise im Serum vorkommenden Mucoproteins verursacht wird. Dieses Mucoprotein enthält Cystein, so dass keine Modifikation der ursprünglichen Interpretierung der Reaktion durchBrdika erforderlich scheint.     

Stereospezifität der Wirkung von Emetin

Summary (-)-Emetine, as prepared by total synthesis, has the same antiamebic activity and toxicity as the natural alkaloid. On the contrary its antipode and rac. isoemetine are not active and practically non-toxic. A relationship between configuration and antiamebic activity has thus been demonstrated for various representatives of the emetine series.     

Experimentally produced ependymal inclusions in the brain ofXenopus laevis

Zusammenfassung Verletzungen des Endhirns beim erwachsenen Krallenfrosch (Xenopus laevis) führen zur Entstehung von Ventrikelteilen, die vollständig oder teilweise vom Ventrikelsystem des Gehirns isoliert sind. Das Ependym solcher Ventrikelteile zeigt stark Chromhämatoxylin-positive cytoplasmatische Einschlüsse (GPI), die im Perikaryon und in den Zellfortsätzen der Tanycyten lokalisiert sind. Charakter und Bedeutung der GPI werden diskutiert.     

Kinetik des Malondialdehydes im Organismus

Summary We followed the kinetics of malonyldialdehyde in vivo and we found that it is very quickly metabolized. This may result in inaccuracy in the estimation of lipoperoxidation in the organism (reaction with 2-thiobarbituric acid).     

Selection and validation of differentially expressed genes in head and neck cancer

We applied a robust combinatorial (multi-test) approach to microarray data to identify genes consistently up- or down-regulated in head and neck squamous cell carcinoma (HNSCC). RNA was extracted from 22 paired samples of HNSCC and normal tissue from the same donors and hybridized to the Affymetrix U95A chip. Forty-two differentially expressed probe sets (representing 38 genes and one expressed sequence tag) satisfied all statistical tests of significance and were selected for further validation. Selected probe sets were validated by hierarchical clustering, multiple probe set concordance, and target-subunit agreement. In addition, real-time PCR analysis of 8 representative (randomly selected from 38) genes performed on both microarray-tested and independently obtained samples correlated well with the microarray data. The genes identified and validated by this method were in comparatively good agreement with other rigorous HNSCC microarray studies. From this study, we conclude that combinatorial analysis of microarray data is a promising technique for identifying differentially expressed genes with few false positives.Received 12 February 2004; received after revision 22 March 2004; accepted 14 April 2004     

β2-integrins mediate a novel form of chemoresistance in cycloheximide-induced U937 apoptosis

In this study with cycloheximide (CHX, an inhibitor of protein synthesis) and the human leukaemic cell line U937, a novel form of chemoresistance, which we termed sudden drug resistance (SDR), was identified using Hoechst33258 staining, Western blott and DNA Ladder. CHX^high (10–100 g/ml)-induced apoptosis can spontaneously subside after 4–6 h or can be inhibited by short-term preincubation with CHXlow (2.5 g/ml). Unlike typical multidrug resistance, SDR is not caused by reduced drug accumulation or altered protein expression, and may be associated with a non-P-glycoprotein mechanism. To uncover this underlying mechanism, we focused on U937 cell aggregation promoted by CHX, because cell adhesion has been suggested to influence cell survival and prevent apoptosis. EDTA, or anti-CD18 monoclonal antibody, but not EGTA, acetylsalicylic acid or RGDS tetrapeptide, abrogated this homotypic aggregation and greatly increased CHX-induced apoptosis in a time-dependent manner, while fibrinogen and soluble intercellular adhesion molecule-1 exerted opposite effects. These results establish that ₂-integrin engagement is a key mediator of SDR, although it may be non-exclusive. This finding supplements the classical basis of chemoresistance and may provide another opportunity for improved leukemia therapy.Received 15 April 2004; received after revision 18 May 2004; accepted 21 June 2004