Construction and optimization of ecological security pattern based on the circuit theory: a case study of Hohhot City.

The construction of ecological security pattern aims to determine the bottom line of ecological land supply and effective spatial distribution and provides a scientific basis for ensuring regional ecological security. The basic paradigm of "source recognition-resistance surface creation-corridor identification-key areas determination" was used to construct the ecological security pattern of Hohhot City in 2009 and 2019. The circuit theory was employed to determine the demand for protection and restoration of crucial ecological area and to divide the core ecological protection and restoration area, the core restoration area, the core protection area, and the general ecological protection area; then, the optimization of Hohhot's ecological security pattern could be proposed. The results show that there was no interconnected and closed ecological network in 2009 and 2019 in the study area, and the area of significant ecological elements were decreasing: ecological source areas decreased from 266.97 to 261.21 km2, the number of ecological corridors decreased from 10 to 6, and the total area of ecological protection and restoration areas decreased from 342.15 to 199.91 km2. The results show that in the past 10 years, the ecological space in Hohhot had problems such as quality degradation, fragmentation intensifying, and effective landscape connectivity declining. It is urgent to optimize the ecological sources layout, strengthen the restoration of barrier areas and the protection of pinch point areas, and improve habitat connectivity to ensure the improved regional ecological security. Our results can provide a scientific reference for coordinating ecological protection and economic development, as well as the policy formulation and implementation of relevant departments.

Integrated assessment and critical obstacle diagnosis of rural resource and environmental carrying capacity with a social-ecological framework: a case study of Liyang county, Jiangsu Province.

The contradiction among human being, resources, and environment has become a significant obstacle to achieving sustainable development, especially in rural areas subject to the spillover of urban development elements. With the immense strain of resources and environment, it is critical to assess whether human activities fall within the carrying capacity range of a natural ecosystem in a rural system. Taking the rural areas of Liyang county as an example, this study aims to assess the rural resource and environmental carrying capacity (RRECC) and diagnose its critical obstacles. Firstly, a social-ecological framework focusing on human-environment interaction was employed to construct the RRECC indicator system. Subsequently, the entropy-TOPSIS method was introduced to assess the performance of the RRECC. Finally, the obstacle diagnosis method was applied to identify the critical obstacles of RRECC. Our results show that the distribution of RRECC presents a spatial heterogeneity, with high- and medium-high-level villages primarily concentrated in the south of the study area, where there are abundant hills and ecological lakes. Medium-level villages are scattered throughout each town, and low and medium-low level villages are concentrated across all the towns. Moreover, the resource subsystem of RRECC (RRECC_RS) exhibits a similar spatial distribution to RRECC, while the outcome subsystem of RRECC (RRECC_OS) has a comparable quantity proportion of different levels to RRECC. Furthermore, the diagnosis results of critical obstacle vary between the town scale divided by administrative units and the regional scale divided by RRECC values. In detail, arable land occupied by construction is the main critical obstacle at the town scale, while the poor people in villages, people left-behind, and arable land occupied by construction are the main critical obstacles at the regional scale. Targeted differentiated improvement strategies for RRECC at regional scale from various perspectives of global, local, and single are proposed. This research can serve as a theoretical foundation for assessing RRECC and developing differentiated sustainable development strategies for the path forward to rural revitalization.

The influence of urban form compactness on CO2 emissions and its threshold effect: Evidence from cities in China.

Although compact urban form plays an important role in constraining emissions of carbon dioxide (CO2), the boundary for the impact of compact urban form on these emissions has nevertheless received little attention. We consequently applied the entropy weight method and several key landscape metrics to a dataset from 295 cities in China to quantify urban form compactness (UFC) between 2000 and 2015. The STIRPAT model then was employed to estimate the impact of UFC on CO2 emissions, and a panel threshold regression model was used to estimate threshold effects capable of limiting the impact of compact urban form on emissions. Although CO2 emissions increased sharply over the 15-year study period, a significant negative relationship between UFC and CO2 emissions was detected. Two thresholds of UFC were detected, and this allowed three categories to be differentiated: before the first threshold, between the two thresholds, and after the second threshold. These categories were respectively associated with no impact, strong impact, and weak impact of UFC on reduction of carbon emissions in the 295 cities. Carbon emissions reduction consequently becomes effective when the UFC exceeds the first threshold and effectiveness persists but at a reduced level when the UFC exceeds the second threshold. Further temporal analysis confirmed that an increasing number of mostly small- and medium-sized cities could constrain their future carbon emissions by adopting a compact urban form. Thus, government policies should emphasize UFC as a strategy to reduce CO2 emissions. Moreover, by defining the range of compact urban form that has the greatest impact on CO2 emissions, our study deepens the overall understanding of the influence of UFC on carbon emission reductions, so as to make contributions to the design of low-carbon cities.

Spliced X-box Binding Protein 1 Stimulates Adaptive Growth Through Activation of mTOR.

BACKGROUND: The unfolded protein response plays versatile roles in physiology and pathophysiology. Its connection to cell growth, however, remains elusive. Here, we sought to define the role of unfolded protein response in the regulation of cardiomyocyte growth in the heart. METHODS: We used both gain- and loss-of-function approaches to genetically manipulate XBP1s (spliced X-box binding protein 1), the most conserved signaling branch of the unfolded protein response, in the heart. In addition, primary cardiomyocyte culture was used to address the role of XBP1s in cell growth in a cell-autonomous manner. RESULTS: We found that XBP1s expression is reduced in both human and rodent cardiac tissues under heart failure. Furthermore, deficiency of XBP1s leads to decompensation and exacerbation of heart failure progression under pressure overload. On the other hand, cardiac-restricted overexpression of XBP1s prevents the development of cardiac dysfunction. Mechanistically, we found that XBP1s stimulates adaptive cardiac growth through activation of the mechanistic target of rapamycin signaling, which is mediated via FKBP11 (FK506-binding protein 11), a novel transcriptional target of XBP1s. Moreover, silencing of FKBP11 significantly diminishes XBP1s-induced mechanistic target of rapamycin activation and adaptive cell growth. CONCLUSIONS: Our results reveal a critical role of the XBP1s-FKBP11-mechanistic target of rapamycin axis in coupling of the unfolded protein response and cardiac cell growth regulation.

Temporal dynamics of cardiac hypertrophic growth in response to pressure overload.

Hypertension is one of the most important risk factors of heart failure. In response to high blood pressure, the left ventricle manifests hypertrophic growth to ameliorate wall stress, which may progress into decompensation and trigger pathological cardiac remodeling. Despite the clinical importance, the temporal dynamics of pathological cardiac growth remain elusive. Here, we took advantage of the puromycin labeling approach to measure the relative rates of protein synthesis as a way to delineate the temporal regulation of cardiac hypertrophic growth. We first identified the optimal treatment conditions for puromycin in neonatal rat ventricular myocyte culture. We went on to demonstrate that myocyte growth reached its peak rate after 8-10 h of growth stimulation. At the in vivo level, with the use of an acute surgical model of pressure-overload stress, we observed the maximal growth rate to occur at day 7 after surgery. Moreover, RNA sequencing analysis supports that the most profound transcriptomic changes occur during the early phase of hypertrophic growth. Our results therefore suggest that cardiac myocytes mount an immediate growth response in reply to pressure overload followed by a gradual return to basal levels of protein synthesis, highlighting the temporal dynamics of pathological cardiac hypertrophic growth.NEW & NOTEWORTHY We determined the optimal conditions of puromycin incorporation in cardiac myocyte culture. We took advantage of this approach to identify the growth dynamics of cardiac myocytes in vitro. We went further to discover the protein synthesis rate in vivo, which provides novel insights about cardiac temporal growth dynamics in response to pressure overload.

Doxorubicin Blocks Cardiomyocyte Autophagic Flux by Inhibiting Lysosome Acidification.

BACKGROUND: The clinical use of doxorubicin is limited by cardiotoxicity. Histopathological changes include interstitial myocardial fibrosis and the appearance of vacuolated cardiomyocytes. Whereas dysregulation of autophagy in the myocardium has been implicated in a variety of cardiovascular diseases, the role of autophagy in doxorubicin cardiomyopathy remains poorly defined. METHODS AND RESULTS: Most models of doxorubicin cardiotoxicity involve intraperitoneal injection of high-dose drug, which elicits lethargy, anorexia, weight loss, and peritoneal fibrosis, all of which confound the interpretation of autophagy. Given this, we first established a model that provokes modest and progressive cardiotoxicity without constitutional symptoms, reminiscent of the effects seen in patients. We report that doxorubicin blocks cardiomyocyte autophagic flux in vivo and in cardiomyocytes in culture. This block was accompanied by robust accumulation of undegraded autolysosomes. We go on to localize the site of block as a defect in lysosome acidification. To test the functional relevance of doxorubicin-triggered autolysosome accumulation, we studied animals with diminished autophagic activity resulting from haploinsufficiency for Beclin 1. Beclin 1(+/-) mice exposed to doxorubicin were protected in terms of structural and functional changes within the myocardium. Conversely, animals overexpressing Beclin 1 manifested an amplified cardiotoxic response. CONCLUSIONS: Doxorubicin blocks autophagic flux in cardiomyocytes by impairing lysosome acidification and lysosomal function. Reducing autophagy initiation protects against doxorubicin cardiotoxicity.

Numerical simulation of compliant artery bypass grafts using fluid-structure interaction framework.

Early researches on the artery bypass graft (ABG) generally took the assumption of rigid vessel wall that ignored the wall compliancy. To obtain more realistic and physiological hemodynamic parameters, a fluid structure interaction study on a complete ABG was carried out. It was concluded: (1) a compliant vessel is able to expand its vessel diameter and decrease its anastomosis angle to achieve a buffer for the blood, thereby helping to reduce endothelial cell injury. (2) The vessel walls experienced their maximum deformation at the time of peak pressure while the deformation could be ignored during diastole. However, the consideration of wall compliance did not quantitatively change the flow characters compared to those of rigid walls. (3) Generally, the hemodynamic priority of helical-type ABG over a conventional one was further strengthened by adopting compliant vessel wall. (4) The consideration of the wall deformation revealed a hidden fact by the rigid wall assumption: Helical ABG aggravated the risk of intimal hyperplasia at its toe region due to its geometry and flow asymmetry. The present study may be useful for surgeons and graft designers to optimize the current and future ABG configurations and selection of materials.