The mdm2 oncogene encodes a 90-kilodalton nuclear phosphoprotein that binds and inactivates the p53 tumor suppressor protein. Here we report the observation of five alternatively spliced mdm2 gene transcripts in a range of human cancers and their absence in normal tissues. Transfection of NIH 3T3 cells with each of these forms gave foci of morphologically transformed cells. A higher frequency of splice variants lacking p53 binding domain sequences was found in late-stage and high-grade ovarian and bladder carcinomas. Four of the splice variants show loss of p53 binding, consistent with partial deletion of sequences encoding the p53 binding domain, but retain carboxyterminal zinc-finger domains. These observations suggest a reassessment of the transforming mechanisms of mdm2 and its relation to p53.

Event-related potentials were recorded in 2 experiments while participants read sentences in a word-byword congruency judgment task. Sentence final words were either congruent, semantically anomalous (Experiments 1 and 2), or neutral (Experiment 2) with respect to sentence context. Half of all final words referred to concrete and half to abstract concepts. A different scalp distribution of the N400 to concrete and abstract final words was found for anomalous and neutral, but not congruent sentences. Although the interaction of context and concreteness is consistent with the context-availability model, the differential scalp distribution of effects for concrete and abstract words, as well as larger context effects for concrete words, was interpreted as being more consistent with an extended dual-code account of semantic processing.

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To determine the significance of the immunophenotypic heterogeneity of B-cell chronic lymphocytic leukaemia (CLL), surface immunoglobulins (SIgs), mouse rosette assays (MR), and a panel of monoclonal antibodies for B cells, T cells and myeloid cells were performed on peripheral blood samples from 61 newly diagnosed cases. Four groups were observed: group I (SIg+, MR+, CD19/20+, CD5+, T antigen (Ag)-; 27 cases); group II (SIg+, MR+, CD19/20+, CD5+, T Ag+; 17 cases); group III (SIg+, MR+ CD19/20+, CD5-, T AG-; 12 cases); and group IV (SIg-, MR+, CD19/20+, Cd5+, T Ag-; 5 cases). Groups were compared according to French-American-British Cooperative Group subtypes, clinical and laboratory features, Rai staging, and survival. Typical CLL morphology (greater than 90% small lymphocytes) was present in 20/20 (100%) of group I cases and 23/27 (85%) group II, III and IV cases (P = 0.09). Expression of a myeloid antigen was seen in 5/27 group I cases (18%) and 1/16 group II cases (6%), but was not predictive of survival (P = 0.36). The CD5- group III had a lower haemoglobin level (P less than 0.0001), higher Rai stage (P less than 0.002), and poorer survival at 5 years (P less than 0.02) than the other groups. We conclude that at least four distinct immunophenotypic subgroups of B-cell CLL can be determined. Expression of myeloid or T-cell antigens does not appear to predict for patient survival; however, lack of CD5 antigen may be associated with more advanced stage of disease and poor patient survival.