Rationale: There is accumulating evidence that a group of stem/progenitor cells (SPCs) maintain alveolar epithelial integrity. Pulmonary emphysema is characterized by the histological finding of the loss of alveolar e...Rationale: There is accumulating evidence that a group of stem/progenitor cells (SPCs) maintain alveolar epithelial integrity. Pulmonary emphysema is characterized by the histological finding of the loss of alveolar epithelial integrity along with corresponding bronchiolar fibrosis. Objectives: Based on the concept of autopoiesis (the capacity to produce oneself), we proposed a mathematical model in the maintenance of alveolar epithelial integrity as related to the genesis of pulmonary emphysema and fibrosis. Methods: A tessellation automaton model was used to describe the autopoietic dynamics of the bronchiolo-alveolar epithelial surface. The alveolar septal volume en-closed by the epithelial surface is a distributed system of discrete elements, which move by random walk in the manner of Brownian motion. Assuming that the numbers of components and events in the automaton are large, an approximate theoretical treatment in terms of differential equations is possible, allowing a set of partial differential equations to be produced. Results: 1) Assuming the loss of progenitor cells through the epithelial-mesenchymal transition (EMT), a sharp bifurcation between two qualitatively distinct regions of the phase space (one that is repaired completely, and another that has disappeared entirely) clearly appeared. 2) Thus, from the system of discrete and spatial partial differential equations, we obtained a system of ordinary differential equations in equilibrium conditions that defined a close relationship between the degree of emphysema, the density of alveolar septal fibroblasts, and the mean concentration of SPCs. Conclusions: A mathematical model of the autopoietic maintenance of the alveolar epithelial surface suggested a close relationship between alveolar emphysema and fibrosis and EMT in lungs affected by chronic obstructive pulmonary disease.展开更多
The definition of life is a very important issue in the philosophy of biology,but this issue has unfortunately been neglected by the mainstream philosopher of biology for many years.In this paper,the difficulties with...The definition of life is a very important issue in the philosophy of biology,but this issue has unfortunately been neglected by the mainstream philosopher of biology for many years.In this paper,the difficulties with and the reasons for defining life are illustrated,the characteristics of life on Earth are explored,ways of defining life are examined,the main definitions of life are explained and evaluated,and finally,a new information definition of life is proposed.展开更多
End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Severa...End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Several ferruginous paleosol intercalations cover periods of drying upward formation (DUP) under semiarid/arid climates. Thin grey pelite beds interbedded between paleosol and overlying FUC, are interpreted as tephra deposits sourced in Siberian LIP- and Neo-Tethys (NT)-Degassing. The Wadi Bassat en Nimra-section exhibits the P-T transitional zone where flash flood deposits meet supra-/intertidal sediments of the southward-directed transgressive NT. Decreasing flash-flooding continued through the Lower Scythian (Ma’in F.) during transgression, reworking, and resedimentation. Two euryhaline foraminifera-bearing limestone beds are discussed as indicators for the end of mass extinction (recovery phase: ca. 250.8 - 250.4 Ma) possibly correlating with the Maximum Flooding Surface MFS Tr 10 (ca. 250.5 Ma) on the Arabian Shelf (Khuff cycles B;A). Comparable data from the Germanic Basin as FUC/DUP-cycles, tephrasuspicious “Grey Beds” with high concentrations of As, Co, Pb, Zn, and Cu as well as the U-Pb Age data of the Siberian LIP meet the PTB-Zone between the MFSs Intervals P 40 (ca. 254 Ma)/Tr 10 (ca 250.5 Ma) on the Arabian Shelf. MFS (Tr 10, 20, 30) and SBs resp. on the Arabian Plate, as well as Scythian Substage boundaries correlate with ∂<sup>13</sup> C-excursions recorded at Musandam, UAE. Thereby, the ratio of greenhouse gases (+climate forcing)/aerosols und tephra (-climate forcing) takes a significant influence on the ∂<sup>13</sup>C-Variation.展开更多
文摘Rationale: There is accumulating evidence that a group of stem/progenitor cells (SPCs) maintain alveolar epithelial integrity. Pulmonary emphysema is characterized by the histological finding of the loss of alveolar epithelial integrity along with corresponding bronchiolar fibrosis. Objectives: Based on the concept of autopoiesis (the capacity to produce oneself), we proposed a mathematical model in the maintenance of alveolar epithelial integrity as related to the genesis of pulmonary emphysema and fibrosis. Methods: A tessellation automaton model was used to describe the autopoietic dynamics of the bronchiolo-alveolar epithelial surface. The alveolar septal volume en-closed by the epithelial surface is a distributed system of discrete elements, which move by random walk in the manner of Brownian motion. Assuming that the numbers of components and events in the automaton are large, an approximate theoretical treatment in terms of differential equations is possible, allowing a set of partial differential equations to be produced. Results: 1) Assuming the loss of progenitor cells through the epithelial-mesenchymal transition (EMT), a sharp bifurcation between two qualitatively distinct regions of the phase space (one that is repaired completely, and another that has disappeared entirely) clearly appeared. 2) Thus, from the system of discrete and spatial partial differential equations, we obtained a system of ordinary differential equations in equilibrium conditions that defined a close relationship between the degree of emphysema, the density of alveolar septal fibroblasts, and the mean concentration of SPCs. Conclusions: A mathematical model of the autopoietic maintenance of the alveolar epithelial surface suggested a close relationship between alveolar emphysema and fibrosis and EMT in lungs affected by chronic obstructive pulmonary disease.
基金This research is financially supported by the research project of National Social Science Foundation of China:“Key Problems in Philosophy of Biology”(14ZDB171).
文摘The definition of life is a very important issue in the philosophy of biology,but this issue has unfortunately been neglected by the mainstream philosopher of biology for many years.In this paper,the difficulties with and the reasons for defining life are illustrated,the characteristics of life on Earth are explored,ways of defining life are examined,the main definitions of life are explained and evaluated,and finally,a new information definition of life is proposed.
文摘End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Several ferruginous paleosol intercalations cover periods of drying upward formation (DUP) under semiarid/arid climates. Thin grey pelite beds interbedded between paleosol and overlying FUC, are interpreted as tephra deposits sourced in Siberian LIP- and Neo-Tethys (NT)-Degassing. The Wadi Bassat en Nimra-section exhibits the P-T transitional zone where flash flood deposits meet supra-/intertidal sediments of the southward-directed transgressive NT. Decreasing flash-flooding continued through the Lower Scythian (Ma’in F.) during transgression, reworking, and resedimentation. Two euryhaline foraminifera-bearing limestone beds are discussed as indicators for the end of mass extinction (recovery phase: ca. 250.8 - 250.4 Ma) possibly correlating with the Maximum Flooding Surface MFS Tr 10 (ca. 250.5 Ma) on the Arabian Shelf (Khuff cycles B;A). Comparable data from the Germanic Basin as FUC/DUP-cycles, tephrasuspicious “Grey Beds” with high concentrations of As, Co, Pb, Zn, and Cu as well as the U-Pb Age data of the Siberian LIP meet the PTB-Zone between the MFSs Intervals P 40 (ca. 254 Ma)/Tr 10 (ca 250.5 Ma) on the Arabian Shelf. MFS (Tr 10, 20, 30) and SBs resp. on the Arabian Plate, as well as Scythian Substage boundaries correlate with ∂<sup>13</sup> C-excursions recorded at Musandam, UAE. Thereby, the ratio of greenhouse gases (+climate forcing)/aerosols und tephra (-climate forcing) takes a significant influence on the ∂<sup>13</sup>C-Variation.
