Rb induces a proliferative arrest and curtails Brn-2 expression in retinoblastoma cells

BACKGROUND: Retinoblastoma is caused by loss of the Rb protein in early retinal cells. Although numerous Rb functions have been identified, Rb effects that specifically relate to the suppression of retinoblastoma have not been defined. RESULTS: In this study, we examined the effects of restoring Rb to Y79 retinoblastoma cells, using novel retroviral and lentiviral vectors that co-express green fluorescent protein (GFP). The lentiviral vector permitted transduction with sufficient efficiency to perform biochemical analyses. Wild type Rb (Rb(WT)) and to a lesser extent the low penetrance mutant Rb(661W )induced a G0/G1 arrest associated with induction of p27(KIP1 )and repression of cyclin E1 and cyclin E2. Microarray analyses revealed that in addition to down-regulating E2F-responsive genes, Rb repressed expression of Brn-2 (POU3F2), which is implicated as an important transcriptional regulator in retinal progenitor cells and other neuroendocrine cell types. The repression of Brn-2 was a specific Rb effect, as ectopic p27 induced a G0/G1 block, but enhanced, rather than repressed, Brn-2 expression. CONCLUSION: In addition to Rb effects that occur in many cell types, Rb regulates a gene that selectively governs the behavior of late retinal progenitors and related cells

Tackling overweight and obesity: Does the public health message match the science?

Background: Despite the increasing understanding of the mechanisms relating to weight loss and maintenance, there are currently no validated public health interventions that are able to achieve sustained long-term weight loss or to stem the increasing prevalence of obesity in the population. We aimed to examine the models of energy balance underpinning current research about weight-loss intervention from the field of public health, and to determine whether they are consistent with the model provided by basic science. EMBASE was searched for papers published in 2011 on weight-loss interventions. We extracted details of the population, nature of the intervention, and key findings for 27 articles.Discussion: Most public health interventions identified were based on a simple model of energy balance, and thus attempted to reduce caloric consumption and/or increase physical activity in order to create a negative energy balance. There appeared to be little consideration of homeostatic feedback mechanisms and their effect on weight-loss success. It seems that there has been a lack of translation between recent advances in understanding of the basic science behind weight loss, and the concepts underpinning the increasingly urgent efforts to reduce excess weight in the population.Summary: Public health weight-loss interventions seem to be based on an outdated understanding of the science. Their continued failure to achieve any meaningful, long-term results reflects the need to develop intervention science that is integrated with knowledge from basic science. Instead of asking why people persist in eating too much and exercising too little, the key questions of obesity research should address those factors (environmental, behavioral or otherwise) that lead to dysregulation of the homeostatic mechanism of energy regulation. There is a need for a multidisciplinary approach in the design of future weight-loss interventions in order to improve long-term weight-loss success

Effect of Attitude Towards Risk on Individual Portfolio Choice at the Nairobi Securities Exchange, Kenya

Attitude towards riskplays a major role of determining a portfolio choice of an investment portfolio composed of a single or multiple assets that an investor chooses within a certain period of time. Although there exist numerous controversial arguments of the factors that determine the level of individual portfolio choice, focus on multidimensional perceptions of investors characteristics have been given little attention. The objective of this study was to determine the effect of investor’s attitude towards risk on individual portfolio choice at the Nairobi securities exchange and  to investigate the moderating effect of investor’s age on the correlation between attitude towards riskand individual portfolio choice on common stocks at the Nairobi securities exchange. The study is anchored on risk aversion theory. A correlational research design was used for collecting data for the variables under study over a period of five years from January, 2013 to December, 2017. The population consisted of individual investors estimated at 2.4 million as at 31st December 2017 based on Central Depository and Settlement Corporation Limited (CDSC). A target population of 997,605 active retail investors who also form the accessible population at Nairobi securities exchange(NSE) were used to draw a sample size of 385 active individual retail investors. Both stratified and convenience sampling was used to select the required number of respondents. A structured questionnaire was used to collect the data whereby drop and pick approach was used by the researcher and research assistants. Pilot testing of the instruments was performed to assess its reliability. Further, multiple regression techniques were used to analyze the data obtained that was presented using frequency tables, means, standard deviations and correlation tables. The study findings revealed that attitude towards risk, have a positive and significant effect on the common stocks. As such a unit increase in a predictor variable leads to an increase in investment in common stocks. Further, the results of the study indicated that age moderate the relationship between attitude towards risk and the individual portfolio choice in respect to common stocks. The study will benefit management of investment banks and brokerage firms in policy formulation to assist individual investors in their portfolio choices and also to the academicians to advance the conceptual arguments of the moderating effect of age on the relationship between attitude towards risk and individual portfolio choice. Keywords: Attitude towards risk, Individual portfolio choice, Risk aversion,Investor’s age. DOI: 10.7176/RJFA/13-20-01 Publication date:October 31st 202

The Challenge of Wide-Field Transit Surveys: The Case of GSC 01944-02289

Wide-field searches for transiting extra-solar giant planets face the difficult challenge of separating true transit events from the numerous false positives caused by isolated or blended eclipsing binary systems. We describe here the investigation of GSC 01944-02289, a very promising candidate for a transiting brown dwarf detected by the Transatlantic Exoplanet Survey (TrES) network. The photometry and radial velocity observations suggested that the candidate was an object of substellar mass in orbit around an F star. However, careful analysis of the spectral line shapes revealed a pattern of variations consistent with the presence of another star whose motion produced the asymmetries observed in the spectral lines of the brightest star. Detailed simulations of blend models composed of an eclipsing binary plus a third star diluting the eclipses were compared with the observed light curve and used to derive the properties of the three components. Our photometric and spectroscopic observations are fully consistent with a blend model of a hierarchical triple system composed of an eclipsing binary with G0V and M3V components in orbit around a slightly evolved F5 dwarf. We believe that this investigation will be helpful to other groups pursuing wide-field transit searches as this type of false detection could be more common than true transiting planets, and difficult to identify.Comment: To appear in ApJ, v. 621, 2005 March 1

An introduction to Trends in Extreme Weather and Climate Events: Observations, Socioeconomic Impacts, Terrestrial Ecological Impacts, and Model Projections

Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.Integrative Biolog

TrES-1: The Transiting Planet of a Bright K0V Star

We report the detection of a transiting Jupiter-sized planet orbiting a relatively bright (V=11.79) K0V star. We detected the transit light-curve signature in the course of the TrES multi-site transiting planet survey, and confirmed the planetary nature of the companion via multicolor photometry and precise radial velocity measurements. We designate the planet TrES-1; its inferred mass is 0.75 +/- 0.07 Jupiter masses, its radius is 1.08 (+0.18/-0.04) Jupiter radii, and its orbital period is 3.030065 +/- 0.000008 days. This planet has an orbital period similar to that of HD 209458b, but about twice as long as those of the OGLE transiting planets. Its mass is indistinguishable from that of HD 209458b, but its radius is significantly smaller and fits the theoretical models without the need for an additional source of heat deep in the atmosphere, as has been invoked by some investigators for HD 209458b.Comment: 15 pages, 3 figures, 2 tables. To be published in Astrophysical Journal Letters. Ascii data in http://www.hao.ucar.edu/public/research/stare/data/TrES1.as

Binary probit estimation of factors affecting pesticide adoption for the control of yam tuber beetles in delta state, Nigeria

Yam is a major staple food crop with significant impact on the food security, income generation and employment creation for the various participants in the yam value-chain in Nigeria. However, pest infestation by yam beetles poses serious production constraint to farmers resulting in over 50% of yield losses. Many farmers have adopted the use of pesticides such as chlorpyriphos. pirimiphos-methyl and deltamethrin to control yam beetles and boost output. Therefore, this study was conducted to examine factors that affect pesticide adoption for control of yam beetles in Oshimili Area of Delta State, Nigeria. Data were obtained from a cross-section of 159 yam farmers including 79 adopters and 80 non-adopters of pesticides, drawn from 6 communities with the aid of questionnaire. t-test and binary probit were employed to analyse the data. The choice of the probit model is due to the qualitative nature of the dependent variable (pesticide adoption). Results of t-test revealed that significant (p < 0.01) differences existed in age, years of formal education, number of adults per household, farm income and farm size between adopters and non-adopters. The probit model had a good fit with significant LR ratio, 106.67 (p < 0.001); a McFadden R2 of 0.48 with 84.9% of cases correctly predicted. The results also showed that age, years of education, adults per household, farming experience, farm income, access to credit, extension contact as well as training on pesticide application all had significant influence on adoption decision. While the impact of age on the probability of technology adoption was negative, all other variables exerted positive effects. The authors recommended that improved access to farm credit, efficient and effective extension service delivery system and on-farm training on pesticide handling and application be intensified to reduce beetles attack, boost yam yield and improve food security of farming households