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Foams in Tissue Engineering
Published in S. T. Lee, Polymeric Foams, 2022
Chenglong Yu, Zhutong Li, Leah K. Gause, Huaguang Yang, Lih-Sheng Turng
For the high demand that tissue engineering is experiencing, the clinical success rate is much lower than needed. There are two main reasons for this shortcoming: the long period of development and the interdisciplinary research needed. For tissue engineering products, the underlying technologies for evaluation and fabrication are less mature, and possibly complex, leading to a long research period. Bringing a relatively simple medical device from the initial design idea to a widespread clinical product frequently takes a minimum of 10 years. Moreover, tissue engineering is an interdisciplinary field where acquired knowledge from anatomy, biomechanics, molecular and developmental biology, polymer chemistry, physics, and many other fields is useful; thus, it is essential to break the borders between different disciplines for substantial leaps [5,6].
Physiological aspects of blastema formation in mice
Published in David M. Gardiner, Regenerative Engineering and Developmental Biology, 2017
Regeneration occurs in response to injury that causes a loss of specific and substantial anatomical structures such as a limb or a digit. In animals that possess regenerative capabilities, the injury response involves a transition from mature tissue through a transient undifferentiated proliferative phase and culminates with the re-differentiation of the replacement structures. In the case of the regenerating limb of salamanders or the digit tip of mice, the transient structure that mediates the regenerative response is called a blastema, and the formation of the blastema distinguishes regeneration from a healing response that simply closes the wound site and culminates in the deposition of an abnormally organized fibrous matrix that is remodeled into scar tissue. At its core, the process of regeneration can be segregated into two important and distinct transformations: (1) the transformation from an injury site composed of mature tissues into the blastema (a transient developmental structure), and (2) the transformation of the blastema to the differentiated replacement structures. Without question, regeneration requires the successful completion of both these transformations; without the first transformation, the ability to complete the second transformation is mute, and without the second transformation, there is no regeneration, regardless of whether or not the first transformation is successful. Herein lies a critical concept for thinking about regeneration: it is a stepwise series of inter-connected and inter-dependent processes that must be firing on all cylinders to be successful. Like an automobile, an airplane, or the space shuttle, it is an amazing engineering feat, and regenerative capability has evolved by natural selection over millions of years to be a well-honed and beautifully crafted mechanism to replace the loss of a functional part of the body. One major goal of regenerative biology is to understand the cellular and molecular bases that drive this regenerative engine, and a second major goal is to understand what components of this engine are non-functional in injury responses that fail to regenerate. In mammals such as the mouse and humans, injury responses typically heal without regeneration and scar formation is the norm; however, there are specific injury models that have retained regenerative capabilities that share similarities with lower vertebrates. In this chapter, we focus on the regenerating mouse digit tip as a model to probe how an amputation wound transforms into a blastema, how the digit blastema transforms by differentiating into the replacement digit tip, and how we can utilize an understanding of this process to enhance regeneration of normally non-regenerative injuries.
Preferred temporal-spatial parameters, physical maturation, and sex are related to vertical and braking forces in adolescent long-distance runners
Published in Sports Biomechanics, 2023
Micah C. Garcia, Bryan C. Heiderscheit, Emily A. Kraus, Grant E. Norte, Amanda M. Murray, David M. Bazett-Jones
Growth and motor control changes that occur during puberty (Freitas et al., 2016) may limit the generalisability of running research in adults to adolescents, especially for less physically mature runners. Less physically mature and female athletes have been observed to land from a jump with higher peak forces and loading rates than more physically mature and male athletes (Quatman et al., 2006). Differences in running kinematics, kinetics, and temporal-spatial parameters have also been observed among males and females of different stages of physical maturation (Garcia et al., 2022; Sigward et al., 2012; Taylor-Haas et al., 2021). The relationships between preferred temporal-spatial parameters and GRFs have not been investigated in adolescent long-distance runners. Investigating the gap of knowledge regarding the interaction among temporal-spatial parameters, physical maturation, and sex with GRFs for adolescent runners may improve our understanding of factors that have been associated with RRIs. The purpose of our study was to investigate the associations between preferred temporal-spatial parameters and GRFs among male and female pre-adolescent and adolescent long-distance runners of different stages of physical maturation. We hypothesised that running with a lower cadence, longer step length, being less physically mature, and being a female would be associated with higher GRFs.
Effect of acetamiprid on the immature murine testes
Published in International Journal of Environmental Health Research, 2018
Hayato Terayama, Ning Qu, Hitoshi Endo, Masatoshi Ito, Hideo Tsukamoto, Kanae Umemoto, Satoshi Kawakami, Yasuhiro Fujino, Masayuki Tatemichi, Kou Sakabe
Spermatogenesis and androgen production represent the main functions of the testes, which produce mature haploid spermatozoa through meiotic divisions. Histologically, testes are roughly divided into seminiferous tubules and interstitium. Spermatozoa, sertoli, and other cells are present in the seminiferous tubules, while Leydig cells and testicular macrophages can be found in the interstitium. Previously, α4, β2, and α7 nAChRs were reported to be expressed in the Leydig cells, sperm, and other reproductive system cells in rats and humans (Ge et al. 2005; Schirmer et al. 2011; Kumar and Meizel 2005). Additionally, decreased testosterone production and decreased spermatozoa generation were observed in mice treated with ACE, clothianidin, and imidacloprid (Kong et al. 2017; Mohamed et al. 2017; Yanai et al. 2017; Mosbah et al. 2018).
A male germ cell assay and supporting somatic cells: its application for the detection of phase specificity of genotoxins in vitro
Published in Journal of Toxicology and Environmental Health, Part B, 2020
Khaled Habas, Martin H. Brinkworth, Diana Anderson
Spermatogenesis is a complex process involving division and differentiation of spermatogonial stem cells into mature spermatozoa. The spermatogenesis process comprises several phases, namely the mitosis proliferation of spermatogonial stem cells to differentiate into spermatocytes, which then undergo meiotic divisions. The division of spermatocyte meiosis to produce haploid round spermatids undergoes spermiogenesis, a differentiation process that comprises the shedding of cytoplasm and compaction of the nucleus of spermatids production of a flagellum and undergoes elongation and condensation of the nucleus, creating elongating and condensing spermatids and untimely mature spermatozoa (Wistuba, Stukenborg, and Marc Luetjens 2007).