Heat & Social Cooperation: The Effects of Thermal Stress on Altruism

Recent literature has highlighted the effects of temperature on economic outcomes and violence in humans, on both the interpersonal and intergroup levels: as temperatures rise, humans are more likely to exhibit increased aggression and agitation. However, little research has been done on how pro-social behaviors like cooperation and altruism among humans might respond to increased temperatures. As extreme heat events increase in frequency, will humans and communities work together in the face of adverse shocks and crises? Leveraging experimental data collected randomized controlled trails held in 4 locations across the world, this paper seeks to establish a relationship between thermal stress and altruistic behaviors. Additionally, we examine whether a trigger, in this case loss in a competition over a shared resource, has any effect on altruism when interacted with extreme heat. Using a linear probability model, we find that there is little evidence for a link between altruism and thermal stress

'Lost years' : West Indian women writing and publishing in Britain c.1960 to 1979.

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN023189 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The Use of Thermal Techniques for the Characterization and Selection of Natural Biomaterials.

In this paper we explore the ability of thermal analysis to check elastin and collagen integrity in different biomaterial applications. Differential Scanning Calorimetry (DSC) has been used to analyze the first and second order transitions of the biological macromolecules in the hydrated and dehydrated state. First, we report the characterization of control cardiovascular tissues such as pericardium, aortic wall and valvular leaflet. Their thermal properties are compared to pure elastin and pure collagen. Second, we present results obtained on two collagen rich tissues: pericardia with different chemical treatments and collagen with physical treatments. Finally, more complex cardiovascular tissues composed of elastin and collagen are analyzed and the effect of detergent treatment on the physical structure of collagen and elastin is brought to the fore

Protein kinase a-regulated assembly of a MEF2·HDAC4 repressor complex controls c-jun expression in vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) maintain the ability to modulate their phenotype in response to changing environmental stimuli. This phenotype modulation plays a critical role in the development of most vascular disease states. In these studies, stimulation of cultured vascular smooth muscle cells with platelet-derived growth factor resulted in marked induction of c-jun expression, which was attenuated by protein kinase Cδ and calcium/calmodulin-dependent protein kinase inhibition. Given that these signaling pathways have been shown to relieve the repressive effects of class II histone deacetylases (HDACs) on myocyte enhancer factor (MEF) 2 proteins, we ectopically expressed HDAC4 and observed repression of c-jun expression. Congruently, suppression of HDAC4 by RNA interference resulted in enhanced c-jun expression. Consistent with these findings, mutation of the MEF2 cis-element in the c-jun promoter resulted in promoter activation during quiescent conditions, suggesting that the MEF2 cis-element functions as a repressor in this context. Furthermore, we demonstrate that protein kinase A attenuates c-Jun expression by promoting the formation of a MEF2-HDAC4 repressor complex by inhibiting salt-inducible kinase 1. Finally, we document a physical interaction between c-Jun and myocardin, and we document that forced expression of c-Jun represses the ability of myocardin to activate smooth muscle gene expression. Thus, MEF2 and HDAC4 act to repress c-Jun expression in quiescent VSMCs, protein kinase A enhances this repression, and platelet-derived growth factor derepresses c-Jun expression through calcium/calmodulin-dependent protein kinases and novel protein kinase Cs. Regulation of this molecular "switch" on the c-jun promoter may thus prove critical for toggling between the activated and quiescent VSMC phenotypes

Decellularization of pericardial tissue and its impact on tensile viscoelasticity and glycosaminoglycan content

Bovine pericardium is a collagenous tissue commonly used as a natural biomaterial in the fabrication of cardiovascular devices. For tissue engineering purposes, this xenogeneic biomaterial must be decellularized to remove cellular antigens. With this in mind, three decellularization protocols were compared in terms of their effectiveness to extract cellular materials, their effect on glycosaminoglycan (GAG) content and, finally, their effect on tensile biomechanical behavior. The tissue decellularization was achieved by treatment with t-octyl phenoxy polyethoxy ethanol (Triton X-100), tridecyl polyethoxy ethanol (ATE) and alkaline treatment and subsequent treatment with nucleases (DNase/RNase). The quantified residual DNA content (3.0 ± 0.4%, 4.4 ± 0.6% and 5.6 ± 0.7% for Triton X-100, ATE and alkaline treatment, respectively) and the absence of nuclear structures (hematoxylin and eosin staining) were indicators of effective cell removal. In the same way, it was found that the native tissue GAG content decreased to 61.6 ± 0.6%, 62.7 ± 1.1% and 88.6 ± 0.2% for Triton X-100, ATE and alkaline treatment, respectively. In addition, an alteration in the tissue stress relaxation characteristics was observed after alkaline treatment. We can conclude that the three decellularization agents preserved the collagen structural network, anisotropy and the tensile modulus, tensile strength and maximum strain at failure of native tissue

Covalent functionalization of decellularized tissues accelerates endothelialization

[EN] In the field of tissue regeneration, the lack of a stable endothelial lining may affect the hemocompatibility of both synthetic and biological replacements. These drawbacks might be prevented by specific biomaterial functionalization to induce selective endothelial cell (EC) adhesion. Decellularized bovine pericardia and porcine aortas were selectively functionalized with a REDV tetrapeptide at 10(-5) M and 10(-6) M working concentrations. The scaffold-bound peptide was quantified and REDV potential EC adhesion enhancement was evaluated in vitro by static seeding of human umbilical vein ECs. The viable cells and MTS production were statistically higher in functionalized tissues than in control. Scaffold histoarchitecture, geometrical features, and mechanical properties were unaffected by peptide anchoring. The selective immobilization of REDV was effective in accelerating ECs adhesion while promoting proliferation in functionalized decellularized tissues intended for blood-contacting applications.JLGR acknowledges financial support from the Spanish State Research Agency (AEI) through the PID2019-106099RB-C41/AEI/10.13039/501100011033 project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.Dal Sasso, E.; Zamuner, A.; Filippi, A.; Romanato, F.; Palmosi, T.; Vedovelli, L.; Gregori, D.... (2021). Covalent functionalization of decellularized tissues accelerates endothelialization. Bioactive materials. 6(11):3851-3864. https://doi.org/10.1016/j.bioactmat.2021.04.003S3851386461