High and low molecular weight crossovers in the longest relaxation time dependence of linear cis-1,4 polyisoprene by dielectric relaxations

The dielectric relaxation of cis-1,4 Polyisoprene [PI] is sensitive not only to the local and segmental dynamics but also to the larger scale chain (end-to-end) fluctuations. We have performed a careful dielectric investigation on linear PI with various molecular weights in the range of 1 to 320 kg/mol. The broadband dielectric spectra of all samples were measured isothermally at the same temperature to avoid utilizing shift factors. For the low and medium molecular weight range, the comparisons were performed at 250 K to access both the segmental relaxation and normal mode peaks inside the available frequency window (1 mHz–10 MHz). In this way, we were able to observe simultaneously the effect of molecular mass on the segmental dynamics—related with the glass transition process—and on the end-to-end relaxation time of PI and thus decouple the direct effect of molecular weight on the normal mode from that due to the effect on the monomeric friction coefficient. The latter effect is significant for low molecular weight (M w < 33 kg/mol), i.e., in the range where the crossover from Rouse dynamics to entanglement limited flow occurs. Despite the conductivity contribution at low frequency, careful experiments allowed us to access to the normal mode signal for molecular weights as high as M w = 320 kg/mol, i.e., into the range of high molecular weights where the pure reptation behavior could be valid, at least for the description of the slowest chain modes. The comparison between the dielectric relaxations of PI samples with medium and high molecular weight was performed at 320 K. We found two crossovers in the molecular weight dependence of the longest relaxation time, the first around a molecular weight of 6.5 ± 0.5 kg/mol corresponding to the end of the Rouse regime and the second around 75 ± 10 kg/mol. Above this latter value, we find a power law compatible with exponent 3 as predicted by the De Gennes theory

Moderation of the Association between Media Exposure and Youth Smoking Onset: Race/Ethnicity, and Parent Smoking

This study of youth smoking onset aims to replicate previously published media moderation effects for race/ethnicity in a national longitudinal multiethnic sample of U.S. adolescents. Previous research has demonstrated that associations between media and smoking during adolescence are greater for Whites than Hispanics or Blacks, and for youth living in non-smoking families. In this study, changes in smoking status over 24 months were assessed among 4,511 baseline never-smokers. The incidence of smoking onset was 14.3% by 24 months with no differences by race/ethnicity. Blacks had higher exposure to movie smoking and overall television viewing compared with Whites and Hispanics. Whites responded to movie smoking regardless of parent smoking but more strongly if their parents were non-smokers. In contrast, Black adolescents showed little behavioral response to any media, regardless of parent smoking. Hispanic adolescents responded only to TV viewing and only when their parents did not smoke. In an analysis assessing the influence of the race of smoking characters on smoking behavior of White and Black adolescents, Whites responded to both White and Black movie character smoking, whereas Blacks responded only to smoking by Black movie characters. Taken as a whole, the findings replicate and extend previous findings, suggesting media factors are more influential among adolescents at low to moderate overall risk for smoking. We draw analogies between these low-moderate risk adolescents and “swing voters” in national elections, suggesting that media effects are more apt to influence an adolescent in the middle of the risk spectrum, compared with his peers at either end of it

The utilization of appropriate osteoporosis medications improves following a multifaceted educational intervention: the Canadian quality circle project (CQC)

<p>Abstract</p> <p>Background</p> <p>Osteoporosis is a serious but treatable condition. However, appropriate therapy utilization of the disease remains suboptimal. Thus, the objective of the study was to change physicians' therapy administration behavior in accordance with the Osteoporosis Canada 2002 guidelines.</p> <p>Methods</p> <p>The Project was a two year cohort study that consisted of five Quality Circle (QC) phases that included: 1) Training & Baseline Data Collection, 2) First Educational Intervention & First Follow-Up Data Collection 3) First Strategy Implementation Session, 4) Final Educational Intervention & Final Follow-up Data Collection, and 5) Final Strategy Implementation Session. A total of 340 family physicians formed 34 QCs and participated in the study. Physicians evaluated a total of 8376, 7354 and 3673 randomly selected patient charts at baseline, follow-up #1 and the final follow-up, respectively. Patients were divided into three groups; the high-risk, low-risk, and low-risk without fracture groups. The generalized estimating equations technique was utilized to model the change over time of whether physicians</p> <p>Results</p> <p>The odds of appropriate therapy was 1.29 (95% CI: 1.13, 1.46), and 1.41 (95% CI: 1.20, 1.66) in the high risk group, 1.15 (95% CI: 0.97, 1.36), and 1.16 (95% CI: 0.93, 1.44) in the low risk group, and 1.20 (95% CI: 1.01, 1.43), and 1.23 (95% CI: 0.97, 1.55) in the low risk group without fractures at follow-up #1 and the final follow-up, respectively.</p> <p>Conclusion</p> <p>QCs methodology was successful in increasing physicians' appropriate use of osteoporosis medications in accordance with Osteoporosis Canada guidelines.</p

Two-year changes in quality of life in elderly patients with low-energy hip fractures. A case-control study

<p>Abstract</p> <p>Background</p> <p>The long-term effect of hip fracture on health-related quality of life (HRQOL) and global quality of life (GQOL) has not been thoroughly studied in prospective case-control studies.</p> <p>Aims</p> <p>a) to explore whether patients with low-energy hip fracture regain their pre-fracture levels in HRQOL and GQOL compared with changes in age- and sex-matched controls over a two year period; b) to identify predictors of changes in HRQOL and GQOL after two years.</p> <p>Methods</p> <p>We examined 61 patients (mean age = 74 years, <it>SD </it>= 10) and 61 matched controls (mean age = 73 years, <it>SD </it>= 8). The Short Form 36 assessed HRQOL and the Quality of Life Scale assessed GQOL. Paired samples <it>t </it>tests and multiple linear regression analyses were applied.</p> <p>Results</p> <p>HRQOL decreased significantly between baseline and one-year follow-up in patients with hip fractures, within all the SF-36 domains (<it>p </it>< 0.04), except for social functioning (<it>p </it>= 0.091). There were no significant decreases within the SF-36 domains in the controls. Significantly decreased GQOL scores (<it>p </it>< 0.001) were observed both within patients and within controls between baseline and one-year follow-up. The same pattern persisted between baseline and two-year follow-up, except for the HRQOL domain mental health (<it>p </it>= 0.193). The patients with hip fractures did not regain their HRQOL and GQOL. Worsened physical health after two years was predicted by being a patient with hip fracture (B = -5.8, <it>p </it>< 0.001) and old age (B = -1.0, <it>p </it>= 0.015), while worsened mental health was predicted by co-morbidity (B = -2.2, <it>p </it>= 0.029). No significant predictors of differential changes in GQOL were identified.</p> <p>Conclusion</p> <p>A hip fracture has a long-term impact on HRQOL and is a strong predictor of worsened physical health. Our data emphasize the importance of preventing hip fracture in the elderly to maintain physical health. This knowledge should be included in decision-making and health care plans.</p

Does Alendronate reduce the risk of fracture in men? A meta-analysis incorporating prior knowledge of anti-fracture efficacy in women

BACKGROUND: Alendronate has been found to reduce the risk of fractures in postmenopausal women as demonstrated in multiple randomized controlled trials enrolling thousands of women. Yet there is a paucity of such randomized controlled trials in osteoporotic men. Our objective was to systematically review the anti-fracture efficacy of alendronate in men with low bone mass or with a history of prevalent fracture(s) and incorporate prior knowledge of alendronate efficacy in women in the analysis. METHODS: We examined randomized controlled trials in men comparing the anti-fracture efficacy of alendronate to placebo or calcium or vitamin D, or any combination of these. Studies of men with secondary causes of osteoporosis other than hypogonadism were excluded. We searched the following electronic databases (without language restrictions) for potentially relevant citations: Medline, Medline in Process (1966-May 24/2004), and Embase (1996–2004). We also contacted the manufacturer of the drug in search of other relevant trials. Two reviewers independently identified two trials (including 375 men), which met all inclusion criteria. Data were abstracted by one reviewer and checked by another. Results of the male trials were pooled using Bayesian random effects models, incorporating prior information of anti-fracture efficacy from meta-analyses of women. RESULTS: The odds ratios of incident fractures in men (with 95% credibility intervals) with alendronate (10 mg daily) were: vertebral fractures, 0.44 (0.23, 0.83) and non-vertebral fractures, 0.60 (0.29, 1.44). CONCLUSION: In conclusion, alendronate decreases the risk of vertebral fractures in men at risk. There is currently insufficient evidence of a statistically significant reduction of non-vertebral fractures, but the paucity of trials in men limit the statistical power to detect such an effect

Does native Trypanosoma cruzi calreticulin mediate growth inhibition of a mammary tumor during infection?

Indexación: Web of Science.Background: For several decades now an antagonism between Trypanosoma cruzi infection and tumor development has been detected. The molecular basis of this phenomenon remained basically unknown until our proposal that T. cruzi Calreticulin (TcCRT), an endoplasmic reticulum-resident chaperone, translocated-externalized by the parasite, may mediate at least an important part of this effect. Thus, recombinant TcCRT (rTcCRT) has important in vivo antiangiogenic and antitumor activities. However, the relevant question whether the in vivo antitumor effect of T. cruzi infection is indeed mediated by the native chaperone (nTcCRT), remains open. Herein, by using specific modified anti-rTcCRT antibodies (Abs), we have neutralized the antitumor activity of T. cruzi infection and extracts thereof, thus identifying nTcCRT as a valid mediator of this effect. Methods: Polyclonal anti-rTcCRT F(ab')(2) Ab fragments were used to reverse the capacity of rTcCRT to inhibit EAhy926 endothelial cell (EC) proliferation, as detected by BrdU uptake. Using these F(ab')(2) fragments, we also challenged the capacity of nTcCRT, during T. cruzi infection, to inhibit the growth of an aggressive mammary adenocarcinoma cell line (TA3-MTXR) in mice. Moreover, we determined the capacity of anti-rTcCRT Abs to reverse the antitumor effect of an epimastigote extract (EE). Finally, the effects of these treatments on tumor histology were evaluated. Results: The rTcCRT capacity to inhibit ECs proliferation was reversed by anti-rTcCRT F(ab')(2) Ab fragments, thus defining them as valid probes to interfere in vivo with this important TcCRT function. Consequently, during infection, these Ab fragments also reversed the in vivo experimental mammary tumor growth. Moreover, anti-rTcCRT Abs also neutralized the antitumor effect of an EE, again identifying the chaperone protein as an important mediator of this anti mammary tumor effect. Finally, as determined by conventional histological parameters, in infected animals and in those treated with EE, less invasive tumors were observed while, as expected, treatment with F(ab')(2) Ab fragments increased malignancy. Conclusion: We have identified translocated/externalized nTcCRT as responsible for at least an important part of the anti mammary tumor effect of the chaperone observed during experimental infections with T. cruzi.http://bmccancer.biomedcentral.com/articles/10.1186/s12885-016-2764-

Improvement in health-related quality of life in osteoporosis patients treated with teriparatide

<p>Abstract</p> <p>Background</p> <p>Individuals with osteoporosis and recent vertebral fractures suffer from pain and impaired health-related quality of life (HRQL). To determine whether patients with osteoporosis treated with teriparatide experienced improvement in HRQL and pain symptoms after several months of therapy.</p> <p>Methods</p> <p>We retrospectively studied a sample of osteoporosis patients treated with teriparatide in a Canadian rheumatology practice. We included patients that received teriparatide therapy with baseline and follow-up Mini-Osteoporosis Quality of Life Questionnaire (OQLQ) data. Follow-up data was measured at three or six months. We used a paired Student's t-test to compare baseline and follow-up measurements for each of the questionnaire's ten questions (five domains). Statistical analysis was also repeated to only include patients who suffered a prior vertebral fracture.</p> <p>Results</p> <p>57 patients were included in the study, including 47 women. The mean age was 63.8 years (standard deviation 12.1 years). About sixty five percent (37/57) had previously sustained one or more osteoporotic fractures and about 38.6% (22/57) had suffered a prior vertebral fracture. About 44% (25/57) of individuals were taking one or more types of pain medications regularly prior to starting therapy. At follow-up, significant improvements were observed in the OQLQ domains of pain symptoms. This was seen when all patients on teriparatide were included, and also when only patients with prior vertebral fractures were included. There was also an improvement in emotional functioning, relating to fear of falling at 3 months follow-up (p = 0.019). Respondents also reported improvement in the domain of activities of daily living, relating to vacuuming at 6 months follow-up (p = 0.036), and an improvement in the leisure domain, relating to ease of traveling in the prior vertebral fracture population at 3 months follow-up (p = 0.012). However, there was no significant improvement observed in the domains of physical functioning. Participants also reported a decrease in need for pain medications, with 26% (15/57) requiring analgesics at the time of follow-up.</p> <p>Conclusion</p> <p>Teriparatide use may be associated with improvements in HRQL in osteoporosis patients, in particular alleviation of pain symptoms. These results were especially evident in patients with a history of vertebral fractures. These findings should be confirmed in larger prospective studies with a suitable control group.</p

Phylogeny of Prokaryotes and Chloroplasts Revealed by a Simple Composition Approach on All Protein Sequences from Complete Genomes Without Sequence Alignment

The complete genomes of living organisms have provided much information on their phylogenetic relationships. Similarly, the complete genomes of chloroplasts have helped to resolve the evolution of this organelle in photosynthetic eukaryotes. In this paper we propose an alternative method of phylogenetic analysis using compositional statistics for all protein sequences from complete genomes. This new method is conceptually simpler than and computationally as fast as the one proposed by Qi et al. (2004b) and Chu et al. (2004). The same data sets used in Qi et al. (2004b) and Chu et al. (2004) are analyzed using the new method. Our distance-based phylogenic tree of the 109 prokaryotes and eukaryotes agrees with the biologists tree of life based on 16S rRNA comparison in a predominant majority of basic branching and most lower taxa. Our phylogenetic analysis also shows that the chloroplast genomes are separated to two major clades corresponding to chlorophytes s.l. and rhodophytes s.l. The interrelationships among the chloroplasts are largely in agreement with the current understanding on chloroplast evolution