Cell-cycle progression is not essential for c-Myc to block differentiation

The c-myc proto-oncogene has been shown to cause blockages to differentiation in many cell lineages. Although the mechanism by which c-Myc affects this process remains unknown, it is considered that it might result indirectly as an outcome of the continued cell-cycle progression invoked by c-Myc in cells which must growth arrest in order to differentiate. However, as there is little evidence to support this hypothesis, it is equally possible that a differentiation blockage occurs through a mechanism independent of c-Myc's involvement in cell-cycle progression. To explore this possibility we utilised a differentiation-defective variant of the U937 cell line, which still responds to the differentiation inducer by undergoing rapid growth arrest. Analysis of this line during growth arrest revealed that, although the expression of the Myc target gene, ornithine decarboxylase (ODC) was down-regulated, the cells differed from those of the parental line in that they continued to express high levels of c-Myc protein, but did not maintain high levels of expression of the Myc antagonists, mad1 and mxi1. Moreover, antisense down-regulation of the c-Myc protein levels in these growth-arrested cells revealed that this continued c-Myc expression was essential for their differentiation blockage. These data therefore indicate that c-Myc can block differentiation by a mechanism dissociated from its ability to direct cell-cycle progression or the expression of ODC.

Myc oncogenes: the enigmatic family

The myc family of proto-oncogenes is believed to be involved in the establishment of many types of human malignancy. The members of this family have been shown to function as transcription factors, and through a designated target sequence bring about continued cell-cycle progression, cellular immortalization and blockages to differentiation in many lineages. However, while much of the recent work focusing on the c-myc oncogene has provided some very important advances, it has also brought to light a large amount of conflicting data as to the mechanism of action of the gene product. In this regard, it has now been shown that c-myc is effective in transcriptional repression as well as transcriptional activation and, perhaps more paradoxically, that it has a role in programmed cell death (apoptosis) as well as in processes of cell-cycle progression. In addition, particular interest has surrounded the distinct roles of the two alternative translation products of the c-myc gene, c-Myc 1 and c-Myc 2. The intriguing observation that the ratio of c-Myc 1 to c-Myc 2 increases markedly upon cellular quiescence led to the discovery that the enforced expression of the two proteins individually showed that c-Myc 2 stimulates cell growth, whereas c-Myc 1 appears to be growth suppressing. Clearly, the disparities in the activities of c-Myc, together with the consistent occurrence of mutations of c-myc in human malignancies, means that, although reaching an understanding of the functions of the myc gene family might not be simple, it remains well worthy of pursuit.

Pain assessment: global use of the Brief Pain Inventory

Poorly controlled cancer pain is a significant public health problem throughout the world. There are many barriers that lead to undertreatment of cancer pain. One important barrier is inadequate measurement and assessment of pain. To address this problem, the Pain Research Group of the WHO Collaborating Centre for Symptom Evaluation in Cancer Care has developed the Brief Pain Inventory (BPI), a pain assessment tool for use with cancer patients. The BPI measures both the intensity of pain (sensory dimension) and interference of pain in the patient's life (reactive dimension). It also queries the patient about pain relief, pain quality, and patient perception of the cause of pain. This paper describes the development of the Brief Pain Inventory and the various applications to which the BPI is suited. The BPI is a powerful tool and, having demonstrated both reliability and validity across cultures and languages, is being adopted in many countries for clinical pain assessment, epidemiological studies, and in studies of the effectiveness of pain treatment.

Sequence analysis of the ZFY and Sox genes in the turtle, Chelydra serpentina

We have sequenced regions of the ZFY and Sox genes in the turtle Chelydra serpentina, a reptile with temperature-dependent sex determination. The ZFY gene in mammals encodes a transcription factor with multiple zinc fingers that may be involved in spermatogenesis as well as other processes. The turtle homologue, Zft, is 92% identical to the ZFY gene at the nucleotide and amino acid levels in the region of zinc fingers 7-12. There are several Sox genes in the turtle that are only 57-70% identical at the nucleotide level and about 55% identical at the amino acid level to the human sex-determining SRY gene. However, the turtle Sox genes, termed TSox, have the conserved motif called the HMG-box (for high mobility group DNA-binding protein) that defines a probable DNA-binding region, and thus are in the same gene family as the Sox genes of other organisms from Drosophila to man. One TSox sequence is identical at the amino acid level to a sequence found in birds, and is 98% identical to a sequence encoded autosomally in mouse and in man. The extent of sequence conservation among the Sox genes suggests that some of their functions may be conserved. Phylogenetic analysis of available Sox sequences including SRY (Sry) sequences suggests that there was a high degree of divergence between any possible immediate common ancestor of the turtle Sox sequences and the SRY (Sry) sequences.

Open-ended attributions for the performance of the elderly

The present study explored open-ended attributions for the success and failure of relatively younger and older men in social and academic situations using a between-subjects design. Attributions were collected from 109 college students and were coded using the Elig and Frieze scheme. Results showed that respondents were more likely to make attributions that combined age with other attributional categories (age-related attributions) than attributions solely to target's age. And, they made more ability-task interaction than ability attributions. Moreover, both attributions were as likely to be made for the elderly adult's success as his failure. Finally, differences also emerged in results from the stability dimension and those for age-related and ability-task attributions indicating that these parameters should be assessed independently in future research.