DNA Damage Recognition and p53 in Cisplatin Resistance

Cis-dichlorodiammineplatinum(II) (cisplatin) is widely used as an anti-cancer agent to treat various tumours particularly ovarian, testicular, bladder cancers and tumours of the head and neck. Although the precise mechanism of cisplatin-mediated cytotoxicity remains elusive, DNA damage is thought to be the therapeutically important interaction. Cisplatin resistance is an obstacle to effective treatment of cancer patients. Such resistance may arise due to a variety of intracellular changes including enhanced repair of DNA lesions caused by cisplatin and reduced susceptibility to DNA damage-induced apoptosis. The tumour suppressor protein, p53 is required for DNA damage-induced apoptosis in certain cell types. Cellular levels of p53 protein are increased subsequent to DNA damage due to post-translational alterations in p53. Induction of p53 protein levels by 1muM cisplatin or transplatin peaks at 24 hours for the cisplatin sensitive human, ovarian adenocarcinoma cell line, A2780. Levels of p53 protein increase in the cisplatin resistant derivative, A2780cp70 for at least 48 hours following treatment with transplatin and at least 72 hours following treatment with cisplatin. Also, certain cisplatin resistant cell lines contain higher basal levels of p53 protein compared to the cisplatin sensitive parental cells from which they were derived. Results of Western blotting experiments show an 8 fold higher p53 concentration in the A2780cp70 cell line than A2780, the cisplatin sensitive parental line. This difference in p53 protein levels does not reflect a mutation of the p53 gene, as direct PCR sequencing of p53 from A2780 and A2780cp70 showed both lines to have a wild-type p53 sequence. Furthermore, the p53 from A2780cp70 has less cross-reactivity with mutant-specific anti-p53 antibodies in immunoprecipitation experiments than cell lines with known mutations of the p53 gene. No evidence for increased MDM2 expression is observed in A2780cp70 suggesting that the p53 protein is not being stabilised by binding to the MDM2 protein in this cell line. Although increased levels of Hsp70 protein are observed in these cells, this may simply reflect a lack of transcriptional repression of the Hsp70 promoter in these cells due to the p53 being non-functional. Altered p53-mediated transcriptional transdiCivwdXion in A2780cp70 was examined by use of a luciferase reporter construct and by Northem blotting of endogenous genes, known to be transcriptionlly activated by p53. A2780cp70 cells have 10 fold lower WAF-1 mRNA levels than A2780 cells indicating reduced p53 transcriptional activity in the resistant cell line. Introduction of a mutant p53 gene into A2780 cells also provokes a reduction in basal p53 levels with a 3 fold decrease detected. Reduced function of p53 in the A2780cp70 cell line would be consistent with reduced entry to the apoptotic pathway in these cells. This may be one reason why A2780cp70 cells are more cisplatin resistant than A2780 cells. The DNA damaging agents, cisplatin and transplatin, induced WAF-1 mRNA levels 4 fold by 24 hours after drug removal in A2780 cells. Ionising radiation provoked a more rapid induction of 4.5 fold by 4 hours after drug removal in A2780 cells. This is consistent with induced p53 protein levels detected in A2780 after similar treatments. A2780cp70 cells, by comparison, showed only slight induction of WAF-1 following treatment with these agents. Clonogenic assay data shows that a pretreatment with cisplatin does not alter sensitivity to a second cisplatin dose. Thus intracellular alterations evoked by cisplatin treatment are not involved in a protective response. DNA damage recognition proteins (DRPs) have been proposed to have a role in drug resistance, possibly by an involvement in DNA repair although other functions are possible. Partial purification of a DRP which binds to cisplatin-damaged DNA was carried out. Using nuclear proteins, soluble in 2% tri-carboxylic acid for anion exchange chromatography and heparin column chromatography, this DRP was purified 183 fold. Using recombinant HMG proteins and using anti-HMG protein antibodies to retard protein-DNA complexes in the gel mobility shift assay, the DRP activity was shown to be identical to HMGl. Evidence is also presented showing that p53 does not directly bind to regions of cisplatin-induced DNA damage. However this does not eliminate a possible link between DRP-mediated DNA damage recognition and the p53 response to DNA damage

Strategies to prevent HIV transmission among heterosexual African-American men

BACKGROUND: As part of qualitative research for developing a culturally sensitive and developmentally appropriate videotape-based HIV prevention intervention for heterosexual African- American men, six focus groups were conducted with thirty African-American men to determine their perceptions of AIDS as a threat to the African-American community, characteristics of past situations that have placed African Americans at risk for HIV infection, their personal high risk behaviors, and suggestions on how HIV intervention videotapes could be produced to achieve maximum levels of interest among African-American men in HIV training programs. METHODS: The groups took place at a low-income housing project in Houston, Texas, a major epicenter for HIV/AIDS. Each group was audiotaped, transcribed, and analyzed using theme and domain analysis. RESULTS: The results revealed that low-income African-American men perceive HIV/AIDS as a threat to their community and they have placed themselves at risk of HIV infection based on unsafe sex practices, substance abuse, and lack of knowledge. They also cite lack of income to purchase condoms as a barrier to safe sex practice. They believe that HIV training programs should address these risk factors and that videotapes developed for prevention should offer a sensationalized look at the effects of HIV/AIDS on affected persons. They further believe that programs should be held in African-American communities and should include condoms to facilitate reduction of risk behaviors. CONCLUSIONS: The results indicate that the respondents taking part in this study believe that HIV and AIDS are continued threats to the African-American community because of sexual risk taking behavior, that is, failure to use condoms. Further, African-American men are having sex without condoms when having sex with women often when they are under the influence of alcohol or other mind-altering substances and they are having sex with men while incarcerated and become infected and once released resume unprotected sexual relations with women. According to the men, substance abuse is an important part of the problem of HIV in the African-American community. This is in keeping with research that shows that drug use, especially crack cocaine, is linked to sexual risk taking among African Americans and to increased likelihood of becoming infected with other sexually transmitted diseases (STDs) including HIV. Thus, interventions for men should address condom use, condom availability, skills for using condoms, eroticizing condoms and substance abuse prevention. Men in the present study also strongly recommended that HIV/AIDS videotaped messages should include footage of the sensational effects of the disease

Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses

Modern Industrial Economics and Competition Policy: Open Problems and Possible Limits

Naturally, competition policy is based on competition economics made applicable in terms of law and its enforcement. Within the different branches of competition economics, modern industrial economics, or more precisely gametheoretic oligopoly theory, has become the dominating paradigm both in the U.S. (since the 1990s Post-Chicago movement) and in the EU (so-called more economic approach in the 2000s). This contribution reviews the state of the art in antitrust-oriented modern industrial economics and, in particular, critically discusses open questions and possible limits of basing antitrust on modern industrial economics. In doing so, it provides some hints how to escape current enforcement problems in industrial economics-based competition policy on both sides of the Atlantic. In particular, the paper advocates a change of the way modern industrial economics is used in competition policy: instead of more and more case-by-cases analyses, the insights from modern industrial economics should be used to design better competition rules

The nature of written feedback: A study of postgraduate lecturers' perspectives

Written feedback is a commonly applied method by which lecturers provide comments to students when a piece of work is assessed. The aim of this study was to capture the espoused views and practice of lecturers when providing written feedback, to ascertain the relationship between views and practice. Using a qualitative methodology, this study explored the views and practices of lecturers who provide written feedback to postgraduate students on assessments. Eleven lecturers teaching postgraduate students within a social sciences faculty in a New Zealand tertiary institution participated in this study. Individual interviews were conducted to gain insight into lecturers’ espoused views on written feedback, and documentary analysis was carried out to explore written feedback practice. One aspect that emerged from the study was the opportunity for lecturers to have a ‘voice’ and engage in discussion about written feedback. This has led to a recommendation for more dialogue around written feedback practice. Key findings from the research study showed that lecturers believed: • that the main role of written feedback was to improve students’ work; • that attributing grades and providing feedback play a fundamental role in written feedback; and • that their own individual style influences the written feedback they provide. It was also found that: • in certain aspects of written feedback, there are clear areas of alignment between what lecturers value and how they actually practice. Recommendations from this study stem from the researcher’s belief, that a deeper understanding of what lecturers think about their written feedback is needed. In addition, the continued use of professional development opportunities to discuss written feedback amongst colleagues is warranted. New lecturers should have an induction and mentoring programme that has a specific emphasis on written feedback, so that written feedback is not lost in the broader topic of assessment. Experienced lecturers should address their own written feedback practice through discussion within their academic programmes, providing examples and exemplars to model the diversity of effective written feedback practice

Barriers and Facilitators for the Donation and Acceptance of Human Breast milk:A Scoping Review

PURPOSE OF REVIEW: Human milk is the best source of nutrients for all infants. When a mother's own milk is unavailable, the World Health Organization suggests using donor human milk for premature neonates with or without medical complications. Exploring the barriers and facilitators for breast milk donation and its acceptability is essential for developing this intervention. A scoping review was conducted based on a methodological framework developed by Arksey and O'Malley (Int J Soc Res Methodol 8:19-32, 2005). A search was conducted in PubMed (NCBI), CINAHL (EBSCO), and Web of Science (Elsevier). A two-stage sequential screening process was adopted. Data extraction was done using a piloted data extraction form. RECENT FINDINGS: We included 20 articles for narrative synthesis. Barriers and facilitators for donating and accepting breast milk were categorized under six themes: individual, family, community, workplace, health system, and policy-related. The common individual barriers were time requirements for BMD, personal dislike of the process, lack of knowledge, insufficient milk, negative opinions, and lack of information. Family stigma, negative rumors, less educated family members, and illness of a family member were identified as family-related barriers. Community-related barriers include cultural or religious unacceptable practices, societal taboos, and distance to milk banks. The major barriers identified in relation to the health system were lack of practical and psychological support, lack of information, storing and transportation issues, lack of knowledge among HCWs, and logistical challenges of creating a milk lab. The common work-related barriers were the lack of adequate time, philosophical objections, and incomprehension at returning to work. Policy-related barriers identified include the need for hygiene requirements, donation costs, and lack of standardized guidelines. Making the donation process faster, providing pick-up services for donors, and community education and male partner engagement regarding breast milk donation could help to boost the acceptability of breast milk donation