On relaxations and aging of various glasses

Slow relaxation occurs in many physical and biological systems. "Creep" is an example from everyday life. When stretching a rubber band, for example, the recovery to its equilibrium length is not, as one might think, exponential: The relaxation is slow, in many cases logarithmic, and can still be observed after many hours. The form of the relaxation also depends on the duration of the stretching, the "waiting time." This ubiquitous phenomenon is called aging, and is abundant both in natural and technological applications. Here, we suggest a general mechanism for slow relaxations and aging, which predicts logarithmic relaxations, and a particular aging dependence on the waiting time. We demonstrate the generality of the approach by comparing our predictions to experimental data on a diverse range of physical phenomena, from conductance in granular metals to disordered insulators and dirty semiconductors, to the low temperature dielectric properties of glasses.     

Autonomous phagosomal degradation and antigen presentation in dendritic cells

Phagocytosis plays a critical role in both innate and adaptive immunity. Phagosomal fusion with late endosomes and lysosomes enhances proteolysis, causing degradation of the phagocytic content. Increased degradation participates in both innate protection against pathogens and the production of antigenic peptides for presentation to T lymphocytes during adaptive immune responses. Specific ligands present in the phagosomal cargo influence the rate of phagosome fusion with lysosomes, thereby modulating both antigen degradation and presentation. Using a combination of cell sorting techniques and single phagosome flow cytometry-based analysis, we found that opsonization with IgG accelerates antigen degradation within individual IgG-containing phagosomes, but not in other phagosomes present in the same cell and devoid of IgG. Likewise, IgG opsonization enhances antigen presentation to CD4(+) T lymphocytes only when antigen and IgG are present within the same phagosome, whereas cells containing phagosomes with either antigen or IgG alone failed to present antigen efficiently. Therefore, individual phagosomes behave autonomously, in terms of both cargo degradation and antigen presentation to CD4(+) T cells. Phagosomal autonomy could serve as a basis for the intracellular discrimination between self and nonself antigens, resulting in the preferential presentation of peptides derived from opsonized, nonself antigens.     

Dislocation-mediated growth of bacterial cell walls

Recent experiments have illuminated a remarkable growth mechanism of rod-shaped bacteria: proteins associated with cell wall extension move at constant velocity in circles oriented approximately along the cell circumference [Garner EC, et al., (2011) Science 333:222-225], [Domínguez-Escobar J, et al. (2011) Science 333:225-228], [van Teeffelen S, et al. (2011) PNAS 108:15822-15827]. We view these as dislocations in the partially ordered peptidoglycan structure, activated by glycan strand extension machinery, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Generation and motion of these interacting defects lead to surprising effects arising from the cylindrical geometry, with important implications for growth. We also discuss how long range elastic interactions and turgor pressure affect the dynamics of the fraction of actively moving dislocations in the bacterial cell wall.     

Gender impact on prognosis of acute coronary syndrome patients treated with drug-eluting stents

Women have a higher risk of adverse outcomes after percutaneous coronary intervention (PCI) than men. However, in acute coronary syndrome (ACS), long-term outcomes after contemporary PCI with drug-eluting stent (DES) have not been fully investigated. We aimed to test the impact of gender on outcomes in patients with ACS after PCI with DES. We analyzed all patients with ACS from the prospective NOBORI-2 trial who underwent PCI with a Nobori DES from 2008 through 2009 in 125 centers worldwide. End points of the study were target lesion failure, cardiac death, myocardial infarction (MI), and clinically driven target lesion revascularization, and major adverse cardiac events (composite of cardiac death, MI, and target vessel revascularization) at 1 year and yearly up to 5 years. There were 1,640 patients with ACS, 1,268 men (77%) and 372 women (23%). Compared to men, women were 5 years older and more frequently had co-morbidities such as diabetes mellitus and hypertension. There were no gender differences for cardiac death (1.3% vs 2.7%), MI (2.1% vs 3.2%), or target lesion revascularization (2.6% vs 3.8%) at 1 year after the procedure for men and women, respectively. The trend was the same at 2 years (cardiac death 2.0% vs 2.3%, MI 2.5% vs 3.5%, target lesion revascularization 3.2% vs 4.6%). Target lesion failure rates were 4.5% and 5.9% at 1 year and 5.7% and 7.3% at 2 years in men and women, respectively (p = NS). Multivariate analysis, which included age, hypertension, diabetes mellitus, and number of diseased vessels, showed that gender was not a predictor for outcome. There were no differences in bleeding or stent thrombosis rates. Relief from anginal symptoms was similar. The same rate of adherence to dual antiplatelet therapy was observed and reached 73% at 1 year and 31% at 2 years after the ACS event and PCI. In conclusion, although women had worse baseline characteristics, no differences in outcomes were observed between men and women treated for ACS with contemporary DES.     

Effectiveness of a pedometer-based program using a socio-cognitive intervention on physical activity and quality of life in a setting of cardiac rehabilitation

Background

Physical activity contributes to improve health and quality of life. However, the prevalence of sedentary lifestyle is elevated after an acute coronary syndrome.

Methods

A randomized controlled trial was performed to evaluate the impact of a pedometer-based program associated with a socio-cognitive intervention on physical activity behaviour, cardiovascular risk factors, and quality of life during the year after an acute coronary syndrome event. During hospitalization, we randomized 32 patients to an experimental group and 33 patients to a usual care group. The experimental intervention included 6 consultations with a clinical nurse specialist during 12 months.

Results

Groups characteristics were comparable. At baseline, the percentage of participants considered in the active range category was similar between groups (31% vs 41%; P = 0.915). However, the proportion of participants who were still active was greater in the experimental group than in the usual care group at 6, 9, and 12 months follow-up (75% vs 41%; 68% vs 36%, and 83% vs 55%, respectively; P < 0.05). After 12 months, changes in overall quality of life and in health and the functioning scores were different between groups (interaction effects [groups by time] P = 0.048 and P = 0.036, respectively).

Conclusions

The use of a pedometer concomitantly with a socio-cognitive intervention improves adherence to physical activity and quality of life during the year after an acute coronary syndrome event. This finding is relevant because physical activity and quality of life are a great concern in preventive cardiology. These results support applying this innovative approach in cardiac rehabilitation programs.