Cell growth inhibition by the Mad/Max complex through recruitment of histone deacetylase activity.

BACKGROUND: The organization of chromatin is crucial for the regulation of gene expression. In particular, both the positioning and properties of nucleosomes influence promoter-specific transcription. The acetylation of core histones has been suggested to alter the properties of nucleosomes and affect the access of DNA-binding transcriptional regulators to promoters. A recently identified mammalian histone deacetylase (HD1) shows homology to the yeast Rpd3 protein, which together with Sin3 affects the transcription of several genes. Mammalian Sin3 proteins interact with the Mad components of the Myc/Max/Mad network of cell growth regulators. Mad/Max complexes may recruit mammalian Rpd3-like enzymes, therefore, directing histone deacetylase activity to promoters and negatively regulating cell growth. RESULTS: We report the identification of a tetrameric complex composed of Max, Mad1, Sin3B and HD1. This complex has histone deacetylase activity which can be blocked by the histone deacetylase inhibitors trichostatin A and sodium butyrate. The inhibition of cell growth by Mad1 is enhanced by Sin3B and HD1, as measured by colony formation assays. Furthermore, a Mad1-induced block of S-phase progression can be overcome by trichostatin A, as shown in microinjection experiments. CONCLUSIONS: The recruitment of a histone deacetylase by sequence-specific DNA-binding proteins provides a mechanism by which the state of acetylation of histones in nucleosomes and hence the activity of specific promoters can be influenced. The finding that Mad/Max complexes interact with Sin3 and HD1 in vivo suggests a model for the role of Mad proteins in antagonizing the function of Myc proteins.

Tumour markers in the diagnosis of bronchial carcinoma: new options using fuzzy logic-based tumour marker profiles.

The diagnosis of lung cancer and early knowledge of its histological type are very important; however, this is still a difficult subject for the physician. The aim of this study was to improve the diagnostic efficiency of tumour markers in the diagnosis of bronchial carcinoma by mathematical evaluation of a tumour marker profile employing fuzzy logic modeling. A panel of five tumour markers, including CYFRA 21-1, CEA, NSE, and five additional parameters was determined in 281 patients with confirmed primary diagnosis of bronchial carcinoma of different histology and stage. A further 131 persons, who had acute and chronic benign lung diseases, served as a control group. A classificator was developed using a fuzzy-logic rule-based system. The diagnostic value of the combined tumour markers was significantly better than that of the individual markers and of a combination of CYFRA 21-1, CEA, and NSE. The discrimination of malignant vs benign diseases was realized with a sensitivity of 87.5% and specificity of 85.5%. The rate of correct classification of small-cell vs non-small-cell lung carcinoma was 90.6% and 91.1%, respectively; for squamous cell carcinoma vs adenocarcinoma it was 76.8% and 78.8%, respectively. Our detailed analysis has shown that the fuzzy logic system improves diagnostic accuracy up to a rate of 20%, especially in early stages and in patients with all marker levels in the grey area. Our concept proved to be more powerful than measurement of single markers or the combination of CEA, CYFRA 21-1, and NSE. Its use may help in distinguishing between malignant and benign disease and make it possible to define different subgroups of patients earlier in the course of their disease.

Antibody capture haemadherence tests for parvovirus B19-specific IgM and IgG.

In the absence of serum inhibitor human parvovirus B19 agglutinates primate red cells. Agglutination of baboon erythrocytes by inhibitor free baculovirus expressed VP1/VP2 proteins of B19 virus was enhanced by low pH. To avoid interference from inhibitor(s) present in serum specimens microtitre tests with an antibody capture configuration were designed and optimised. Antigen binding was demonstrated by the adherence of baboon erythrocytes. These tests (MACHAT, GACHAT) detected IgM or IgG anti-B19 in 1032 serum specimens with an overall sensitivity of 99%, specificity of 98.2% and positive predictive value of 96.8% with reference to the radioimmunoassays currently in diagnostic use. MACHAT and GACHAT are straightforward, and well suited to large scale research and seroepidemiological investigations. They are without the risks from infectious antigen and radiation associated with existing radioimmunoassays and allow the phenomenon of B19 virus haemagglutination to be put to practical advantage.