ABSTRACT
Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients.
Subject(s)
Tissue Engineering , Bioprinting , Elastic Modulus , Freeze Drying , Humans , Lab-On-A-Chip Devices , Polymers/chemistry , Regenerative Medicine , Tissue Scaffolds/chemistryABSTRACT
Gammadelta T lymphocytes have a heterodimeric complex formed by the association of gamma and delta chains as receptor. Proliferation of this lymphocyte population has been observed, when infection by several pathogens such as Mycobacterium tuberculosis and Plasmodium spp. occurs. The New World Monkey Aotus nancymaae has become a very good experimental model for the immunological and physiopathological study of these infectious agents. The A. nancymaae gamma-variable region was characterized from peripheral blood samples by using cDNA and genomic DNA polymerase chain reaction amplification, DNA sequencing, and dot-blot hybridization techniques. Seventeen different T-cell receptor gamma-variable (TCRGV) sequences were obtained. These sequences were distributed among TCRGV subsets 1, 2, or 3, according to human subset classification. Although no subset 4 amplification was obtained, this subset was detected by dot-blot hybridization. The presence of these 4 subsets resembles the behavior displayed by 'gammadelta-low species' (humans and mice), where high diversity among these lymphocytes can be observed. Homologies greater than 70% were found with respect to humans. Sequence convergence between human and A. nancymaae subsets 1 and 3 highlights Aotus as a promising model for studying these lymphocyte functions.
Subject(s)
Aotidae/blood , Aotidae/genetics , Genes, T-Cell Receptor gamma/physiology , Amino Acid Sequence , Animals , Evolution, Molecular , Hybridization, Genetic , Molecular Sequence Data , Phylogeny , Sequence Alignment , Sequence Homology, Amino AcidABSTRACT
Optical pumping of polymer sheets containing laser dyes and TiO(2) nanoparticle scatterers results in emissions that exhibit laser behavior with linewidths as low as 4 nm. The input-output characteristics, effects of index matching on the emission, damage thresholds, wavelength stability, and possible applications of these new materials are discussed.
ABSTRACT
The characterization of the emission from nylon fibers containing laser dyes and TIO(2) nanoparticle scatterers indicates laser behavior with linewidths as low as 4 nm in 200- to 800-µm fibers. These materials can be used to produce lasing textiles, which can be used to produce photonic codes for a variety of civilian and military applications.