p53 in polyoma virus transformed REF52 cells

While cellular transformation by small DNA tumour viruses usually involves targeting the product of the p53 tumour suppressor gene by a virally encoded protein, none of the three polyoma virus (Py) specified T antigens have been observed to interact with p53. We show that primary mouse embryo fibroblasts and REF52 cells, which resemble primary cells in requiring co-operating oncogenes for transformation, cannot be transformed by the Py oncogene, middle T-antigen (PyMT), alone. These cells can be transformed by the complete Py early region, which encodes the Py large, middle and small T-antigens. We find that PyMT can transform rodent cells lacking a functional p53 protein (p53 null mouse embryo fibroblasts and DN-REF52 cells which contain a dominant negative p53). In Py transformed REF52 cells (Py-REF52) there is no significant accumulation of p53 protein, as opposed to SV40 transformed REF52 cells (SV-REF52) in which the amount of steady state p53 protein is elevated. However accumulation of p53 is observed following exposure of Py-REF52 cells to u.v. Treatment of Py-REF52 cells with X-rays results in a rapid increase in the levels of the p53-induced proteins p21/WAF1 and MDM2. In untransformed REF52 cells, X-irradiation causes p53 activation, which results in induction of both G1/S and G2/M blocks. In SV-REF52 and DN-REF52 cells, p53 abrogation results in the absence of both the G1/S and G2/M blocks. Only the absence of a G1/S block is observed in Py-REF52 cells exposed to X-irradiation. Together these results indicate that in contrast to most other DNA tumour viruses, Py does not appear to interfere with the DNA damage induced transactivation activities of the p53 protein but absence of a functional p53 protein can mediate transformation by the PyMT oncogene in the absence of other co-operating oncogenes. Possible modes of transformation by Py are discussed.     

Performance analysis of Drever-Hall laser frequency stabilizationusing a proportional+integral servo

In this paper, we derive analytical expressions for finite gain, finite bandwidth laser frequency locking systems. The common case of Drever-Hall (FM sideband) locking to a Fabry-Perot cavity is discussed, using a proportional+integral (PI) controller as an example. The effects of nonnegligible loop time-delay on stability are discussed, and an optimal design procedure for a frequency locking system is given     

Dyadic perfectionism as a predictor of relationship continuity and distress among college students.

This study examined the nature and impact of dyadic perfectionism over a 3-month interval within a sample of 116 college students who were currently involved in an intimate heterosexual relationship. Dyadic perfectionism scores were stable and correlated as expected with scores on concurrent measures of adult attachment orientations and relationship satisfaction. Logistic regression analyses revealed that, controlling for initial commitment status and adult attachment orientations, Time 1 dyadic perfectionism scores significantly and uniquely predicted relationship continuity 3 months later. Lastly, controlling for social desirability, relationship commitment status, and Time 1 adult attachment orientation scores, Time 1 dyadic perfectionism scores also uniquely predicted Time 2 relationship distress. Findings provide additional evidence that dyadic perfectionism is a risk factor for relationship dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intergranular films at Au-sapphire interfaces

The existence of nanometer-thick amorphous equilibrium films at metal-ceramic interfaces has been experimentally verified for the Au–Al₂O₃ system. The films were formed using a novel experimental approach, in which thin sputtered films of Au were dewetted on a sapphire substrate which was previously partially wetted with drops of anorthite glass (CaO–2SiO₂–Al₂O₃). High-resolution transmission electron microscopy and qualitative analytical transmission electron microscopy were used to confirm the existence of the amorphous films. In addition, positive and relatively large Hamaker constants were calculated for the Au-film-Al₂O₃ interface, which indicates the existence of an attractive van der Waals force which stabilizes the film, similar to equilibrium films at grain boundaries in ceramics. A ∼ 1 nm thick surface film was also detected on the (0001) surface of sapphire substrates partially wetted by anorthite glass. The refractive index required to stabilize the surface films, via a positive Hamaker constant, is explored.     

Determination of sulphonamide residues in cattle meats by the Charm-II system and validation with high performance liquid chromatography with fluorescence detection

The purpose of this study was determination of sulphonamide residues (sulphanilamide, sulphadiazine, sulphathiazole, sulphamerazine, sulphamethazine, sulphamethoxazole, and sulphadimethoxine) in cattle meat by the Charm II technique and the validation of sulphonamide levels by high performance liquid chromatography with fluorescence detector (HPLC-FLD). Of 157 meat samples, 9 samples (5.73%) were found positive by the Charm II method. To make quantitative confirmation of sulphonamide content of positive samples, HPLC-FLD was used and four samples were confirmed as positive. In HPLC analysis, the limit of detection (LOD) was in the range 8–15 μg/kg and the limit of quantification (LOQ) was 13–25 μg/kg. Average recoveries of sulphonamides ranged from 44.6% to 81% with relative standard deviations below 6% (n = 6). In conclusion, we consider that the results obtained in field screening by only using the Charm II system, as is common practice in Turkey and worldwide, are inadequate and thus the results should be confirmed by sensitive systems like HPLC.     

An approach to textile dye removal using sawdust from Aspidosperma polyneuron

The textile industry is responsible for discarding wastewater contaminated with dyes. The timber industry generates waste in the form of sawdust. The aim of the present study was to evaluate the adsorptive potential of sawdust obtained from the Aspidosperma polyneuron tree for the removal of the textile dye from wastewater. Sawdust was subjected to different pre-treatments (acid, alkaline and polyethyleneimine) in order to increase its adsorption capacity. Based on the results from the isotherms, treatment with polyethyleneimine (PEI) led to the greatest adsorption capacity and fits the Freundlich model, indicating cooperative adsorption. Other treatments with sawdust best fit the Langmuir model, but the untreated sawdust presented better results than the treated sawdust. These results were only surpassed by sawdust treated with PEI. A. polyneuron revealed good potential for use as an adsorbent to remove dyes, which is a novel result, since to date there is no study on its use as a sorbent material.     

International Regulations of Propolis Quality: Required Assays do not Necessarily Reflect their Polyphenolic‐Related In Vitro Activities

Propolis has been proposed as a polyphenolic‐rich natural product potentially able to be used for human consumption or even for medicinal proposes. To guarantee a minimum phenolic and flavonoid content and as consequence of their related‐biological activities, international requirements of propolis quality are commonly applied. In this work we assessed phenolic and flavonoid contents of propolis; the antioxidant capacity (toward peroxyl radicals and hypochlorous acid); the ability to generate nitric oxide (NO); and, finally the antimicrobial activity of 6 propolis samples from the VI region of Chile. Our results show that the total phenolic and flavonoid content of propolis samples are not always in agreement with their polyphenolic‐associated in vitro activities. For example, P03 and P06 samples showed the lowest (25 ± 4 GAE/g propolis) and the highest (105 ± 3 GAE/g propolis) total phenolic content, respectively. This was in agreement with flavonoid content and their Oxygen Radical Absorbance Capacity (ORAC) activity. However, this dependence was not observed toward HOCl, NO release and antimicrobial activity. Based on our results, we consider that, in order to guarantee the antioxidant or antimicrobial in vitro effects, the international regulations of propolis quality should contemplate the convenience of incorporating other simple analytical test such as ORAC or antimicrobial tests.     

RT-PCR comparative study of viral load levels in the HIV positive population in Puerto Rico before and after protease inhibitor regimen implanted

Ponce School of Medicine AIDS Research Program conducted a large scale viral load assessment of Puerto Ricans who are infected by human immunodeficiency virus type 1 (HIV-1) during the summer of 1996 through the Roche ACCESS program before general implementation of combination therapy. Since January 1997, it has monitored those HIV-1 patients who are under treatments at most HIV-1 health care clinics, including both public and private. The present study was conducted to evaluate how the new treatment has generally impacted on the HIV-1 disease status of HIV-1 infected population in the eight Immunology Clinics. Assessment was made by consecutively monitoring the changes in HIV-1 viral load profiles of the population from January to September, 1997. A large majority of samples were delivered for viral load assessment without information of their treatment status, and only a small number of samples were identifiable either as baseline or followup. Despite the paucity of individual information, remarkable improvements of HIV-1 (+) population at large were evident. For example, in the summer of 1996 (ACCESS), population median viral load was 51,842; only 9% of the population had viral load less than 500 viral RNA copies/ml plasma and 72% had over 10,000 copies/ml. By July-September, 1997, the population median dropped to 8,679 (83%); 23% were below 500 copies/ml (+156%) and the proportion of patients who had over 10,000 copies/ml was reduced to 48% (-33%). The group of individuals who were positively identified as "follow-up" (i.e., under active treatment) had a median of 37128 copies/ml (-94%); 28% were below 500 copies/ml (+211%) and only 40% had more than 10,000 copies/ml (-44%). It is obvious that the implementation of triple combination therapy by PASET in 1997, has very markedly improve the HIV-1 disease status of HIV-1 (+) population in Puerto Rico.     

Asymptotic convergence of scheduling policies with respect to slowdown

We explore the performance of an M/GI/1 queue under various scheduling policies from the perspective of a new metric: the slowdown experienced by the largest jobs. We consider scheduling policies that bias against large jobs, towards large jobs, and those that are fair, e.g., processor-sharing (PS). We prove that as job size increases to infinity, all work conserving policies converge almost surely with respect to this metric to no more than 1/(1−ρ), where ρ denotes the load. We also find that the expected slowdown under any work conserving policy can be made arbitrarily close to that under PS, for all job sizes that are sufficiently large.