p53, a Novel Inhibitor of Apoptosis

p53 is a transcription factor known to induce apoptosis via transactivating the expression of pro-apoptotic proteins and by directly activating the mitochondria apoptotic pathway. p53 is also found to be mutated in 50% of human cancers with some of these tumours overexpressing both wild type (WT) and mutant p53. Overexpression of the p53 protein has been implicated with the more aggressive nature of these tumour cells, suggesting a possible gain-of-function of such mutants. In this study, the involvement of p53 in apoptosis via the caspase pathway was investigated. WT-p53 and three mutant p53 with mutations at the 1) N-terminus (D42Y), 2) central domain (R175H) and 3) C-terminus (R337H) were selected. The data collected demonstrated that p53 was able to inhibit the cleavage of caspases early in the apoptotic pathway. In vitro assays showed that addition of recombinant WT and the mutant p53 inhibited the cleavage of both caspase-9 and caspase-3 and subsequently PARP, while overexpression of p53 in mammalian cells yielded the same inhibition profile in vivo. Conversely, removal of p53 via siRNA and immunodepletetion showed accelerated caspase-9 activity and cleavage. Immunoprecipitation experiments and recombinant assay systems suggest that the inhibition by p53 is targeted at the active cleaved caspase-9. In addition, the presence of p53 (WT or mutant) in p53-null cells were able to confer a higher survival rate. These data therefore demonstrate that p53 may have an additional anti-apoptotic role via the inhibition of caspase-9, which is often masked by its pro-apoptotic functions. This anti-apoptotic role could manifest itself in a cancer background overexpressing mutant p53 which has lost its transcriptional activity and hence its ability to induce apoptosis via the induction of pro-apoptotic genes such as PUMA and NOXA. This newly discovered role of p53 could potentially explain the aggressive nature of cancers which overexpress p53

The Impact of Immigration on U.S. Trade: A Comparative Study

Immigrants play an important role in affecting bilateral trade. Immigrant links to the home country include knowledge of home country markets, language, preferences, and business contacts. This paper investigates the link between immigration and trade using United States trade data. It analyzes the original study by Gould and the reduced trading partners\u27 study, compares two different time period, and analyzes the role of new variables in the trade equation. The results of this study are divided into three sections. The first section of this study which compares Gould\u27s original study to the modified Gould\u27s study reveals that immigrants influence loses its significance when the sample size decreases. The second section compares the immigrants\u27 effect for the two different time period. Immigrant information variable is found to have minimal significance for the 1970 - 1986 time period but are found to affect exports in the 1987 - 1999 time period. Contrary to previous studies, immigrant information variable does not facilitate exports but reduce it. In the final section, Distance and English-Language variable are included in the study. Empirical results suggest that Distance affect import flows but have no effect on export flows. English-Language is found to be statistically insignificant in the model

Chronic hepatitis B - New goals, new treatment

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Updates in the treatment of chronic hepatitis B

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