ABSTRACT
The perceived duration of a visual stimulus depends on various features, such as its size, shape, and movement. Potential effects of stimulus color have not been investigated in sufficient detail yet, but the well-known effects of arousal on time perception suggest that arousing hues, such as red, might induce an overestimation of duration. By means of a two-interval duration discrimination task in the sub-second range, we investigated whether participants overestimate the duration of red stimuli in comparison to blue stimuli, while controlling for differences in brightness (individual adjustments by means of flicker photometry) and saturation (colorimetric adjustment in terms of the CIELAB color space). Surprisingly, our results show an overestimation of the duration of blue compared to red stimuli (indicated by a shift of the point of subjective equality), even though the red stimuli were rated as being more arousing. The precision (variability) of duration judgments, i.e., the duration difference limen, did not differ between red and blue stimuli, questioning an explanation in terms of attentional processes.
Subject(s)
Color Perception , Time Perception , Adult , Female , Humans , Male , Photic Stimulation , Young AdultABSTRACT
Cryogels made of components of natural extracellular matrix components are potent biomaterials for bioengineering and regenerative medicine. Human dermal fibroblasts are key cells for tissue replacement during wound healing. Thus, any biomaterial for wound healing applications should enable growth, differentiation and matrix synthesis by these cells. Cryogels are highly porous scaffolds consisting of a network of interconnected pores. Here, we used a novel group of cryogels generated from acrylated hyaluronan where the polymerization was initiated by accelerated electrons (E-beam). This novel procedure omits any toxic polymerization initiators and results in sterile, highly elastic scaffolds with adjustable pore size, excellent swelling and low flow resistance properties. We show that these cryogels are effective 3D-substrates for long-term cultures of human dermal fibroblasts in vitro. The cells proliferate for at least 28days throughout the cryogels and deposit their own matrix in the pores. Moreover, key modulators of dermal fibroblasts during wound healing like TGFß and PDGF efficiently stimulated the expression of wound healing-relevant genes. In conclusion, electron beam initiated cryogels of acrylated hyaluronan represent a functional and cell compatible biomaterial that could be adapted for special wound healing applications by further functionalization.
Subject(s)
Acrylates/pharmacology , Cryogels/pharmacology , Electrons , Extracellular Matrix/metabolism , Fibroblasts/drug effects , Hyaluronic Acid/pharmacology , Acrylates/chemistry , Biocompatible Materials , Cell Proliferation/drug effects , Cryogels/chemical synthesis , Dermis/cytology , Dermis/metabolism , Elasticity , Extracellular Matrix/chemistry , Female , Fibroblasts/cytology , Fibroblasts/metabolism , Humans , Hyaluronic Acid/chemistry , Male , Platelet-Derived Growth Factor/pharmacology , Polymerization , Porosity , Primary Cell Culture , Tissue Engineering , Tissue Scaffolds , Transforming Growth Factor beta/pharmacologyABSTRACT
The difference in the reactivity of tyrosine and histidine residues in mono- and heteroclonal IgG protein toward enzyme catalyzed and chemical iodination has been studied. One heteroclonal and four monoclonal IgG proteins were iodinated using lactoperoxidase or chloramine T. The ratio of the degrees of substitution of the light and the heavy chains varied from IgG to IgG. One of the monoclonal IgG proteins, IgG-Dam, could only be modified in the gamma-chain. The lack of reactivity was attributed to steric hindrance and other local peculiarities. This interpretation is supported by spectrophotometric titration studies.
