Background: We developed a mobile device application and dedicated pelvic positioner with the aim of improving the acetabular cup placement accuracy in patients undergoing total hip arthroplasty (THA). The function of the application was to display the intra-operative cup angle. The accuracy and clinical usefulness of this combined method were verified through comparison with the conventional alignment guide method.
View Article and Find Full Text PDFA great variety of molecular components is encapsulated in cells. Each of these components is replicated for cell reproduction. To address the essential role of the huge diversity of cellular components, we studied a model of protocells that convert resources into catalysts with the aid of a catalytic reaction network.
View Article and Find Full Text PDFThe emergence of replicases that can replicate themselves is a central issue in the origin of life. Recent experiments suggest that such replicases can be realized if an RNA polymerase ribozyme is divided into fragments short enough to be replicable by the ribozyme and if these fragments self-assemble into a functional ribozyme. However, the continued self-replication of such replicases requires that the production of every essential fragment be balanced and sustained.
View Article and Find Full Text PDFIntroduction: We report a case of acute tetraplegia, without any trauma or symptoms prior to onset, who presented with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine with concomitant spinal cord infarction.
Case Presentation: A 64-year-old man with a number of risk factors for vascular disease was admitted to our hospital with progressive motor weakness in the bilateral upper and lower extremities. He had initially felt numbness in his left upper extremity and had no previous neurological symptoms or trauma.
Cell reproduction involves replication of diverse molecule species, in contrast to a simple replication system with fewer components. To address this question of diversity, we study theoretically a cell system with catalytic reaction dynamics that grows by uptake of environmental resources. It is shown that limited resources lead to increased diversity of components within the system, and the number of coexisting species increases with a negative power of the resource uptake.
View Article and Find Full Text PDFBackground: All life, including cells and artificial protocells, must integrate diverse molecules into a single unit in order to reproduce. Despite expected pressure to evolve a simple system with the fastest replication speed, the mechanism by which the use of a great variety of components, and the coexistence of diverse cell-types with different compositions are achieved is as yet unknown.
Results: Here we show that coexistence of such diverse compositions and cell-types is the result of competitions for a variety of limited resources.
Explanation of the emergence of primitive cellular structures from a set of chemical reactions is necessary to unveil the origin of life and to experimentally synthesize protocells. By simulating a cellular automaton model with a two-species hypercycle, we demonstrate the reproduction of a localized cluster; that is, a protocell with a growth-division process emerges when the replication and degradation speeds of one species are respectively slower than those of the other species, because of overcrowding of molecules as a natural outcome of the replication. The protocell exhibits synchrony between its division process and replication of the minority molecule.
View Article and Find Full Text PDFRecent experimental observations suggest that cells can show relatively precise and reliable responses to external signals even though substantial noise is inevitably involved in the signals. An intriguing question is the way how cells can manage to do it. One possible way to realize such response for a cell is to evolutionary develop and optimize its intracellular signaling pathways so as to extract relevant information from the noisy signal.
View Article and Find Full Text PDFAdv Exp Med Biol
January 2013
Microscopic biological processes have extraordinary complexity and variety at the sub-cellular, intra-cellular, and multi-cellular levels. In dealing with such complex phenomena, conceptual and theoretical frameworks are crucial, which enable us to understand seemingly different intra- and inter-cellular phenomena from unified viewpoints. Decision-making is one such concept that has attracted much attention recently.
View Article and Find Full Text PDFA variety of cellular functions are robust even to substantial intrinsic and extrinsic noise in intracellular reactions and the environment that could be strong enough to impair or limit them. In particular, of substantial importance is cellular decision-making in which a cell chooses a fate or behavior on the basis of information conveyed in noisy external signals. For robust decoding, the crucial step is filtering out the noise inevitably added during information transmission.
View Article and Find Full Text PDFFor understanding the origin of life, it is essential to explain the development of a compartmentalized structure, which undergoes growth and division, from a set of chemical reactions. In this study, a hypercycle with two chemicals that mutually catalyze each other is considered in order to show that the reproduction of a protocell with a growth-division process naturally occurs when the replication speed of one chemical is considerably slower than that of the other chemical, and molecules are crowded as a result of replication. It is observed that the protocell divides after a minority molecule is replicated at a slow synthesis rate, and thus, a synchrony between the reproduction of a cell and molecule replication is achieved.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
December 2009
A power-law distribution is found in the density profile of reacting systems A+B-->C+D and 2A-->2C under a flow in two and three dimensions. Different densities of reactants A and B are fixed at both ends. For the reaction A+B , the concentration of reactants asymptotically decay in space as x-1/2 and x-3/4 in two dimensions and three dimensions, respectively.
View Article and Find Full Text PDF© LitMetric 2025. All rights reserved.