Decoding the spermatogonial stem cell niche under physiological and recovery conditions in adult mice and humans

The intricate interaction between spermatogonial stem cell (SSC) and testicular niche is essential for maintaining SSC homeostasis; however, this interaction remains largely uncharacterized. In this study, to characterize the underlying signaling pathways and related paracrine factors, we delineated the intercellular interactions between SSC and niche cell in both adult mice and humans under physiological conditions and dissected the niche-derived regulation of SSC maintenance under recovery conditions, thus uncovering the essential role of C-C motif chemokine ligand 24 and insulin-like growth factor binding protein 7 in SSC maintenance. We also established the clinical relevance of specific paracrine factors in human fertility. Collectively, our work on decoding the adult SSC niche serves as a valuable reference for future studies on the aetiology, diagnosis, and treatment of male infertility.</p

Seizing the window of opportunity to mitigate the impact of climate change on the health of Chinese residents

The health threats posed by climate change in China are increasing rapidly. Each province faces different health risks. Without a timely and adequate response, climate change will impact lives and livelihoods at an accelerated rate and even prevent the achievement of the Healthy and Beautiful China initiatives. The 2021 China Report of the Lancet Countdown on Health and Climate Change is the first annual update of China’s Report of the Lancet Countdown. It comprehensively assesses the impact of climate change on the health of Chinese households and the measures China has taken. Invited by the Lancet committee, Tsinghua University led the writing of the report and cooperated with 25 relevant institutions in and outside of China. The report includes 25 indicators within five major areas (climate change impacts, exposures, and vulnerability; adaptation, planning, and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement) and a policy brief. This 2021 China policy brief contains the most urgent and relevant indicators focusing on provincial data: The increasing health risks of climate change in China; mixed progress in responding to climate change. In 2020, the heatwave exposures per person in China increased by 4.51 d compared with the 1986–2005 average, resulting in an estimated 92% increase in heatwave-related deaths. The resulting economic cost of the estimated 14500 heatwave-related deaths in 2020 is US$176 million. Increased temperatures also caused a potential 31.5 billion h in lost work time in 2020, which is equivalent to 1.3% of the work hours of the total national workforce, with resulting economic losses estimated at 1.4% of China’s annual gross domestic product. For adaptation efforts, there has been steady progress in local adaptation planning and assessment in 2020, urban green space growth in 2020, and health emergency management in 2019. 12 of 30 provinces reported that they have completed, or were developing, provincial health adaptation plans. Urban green space, which is an important heat adaptation measure, has increased in 18 of 31 provinces in the past decade, and the capacity of China’s health emergency management increased in almost all provinces from 2018 to 2019. As a result of China’s persistent efforts to clean its energy structure and control air pollution, the premature deaths due to exposure to ambient particulate matter of 2.5 μm or less (PM2.5) and the resulting costs continue to decline. However, 98% of China’s cities still have annual average PM2.5 concentrations that are more than the WHO guideline standard of 10 μg/m3. It provides policymakers and the public with up-to-date information on China’s response to climate change and improvements in health outcomes and makes the following policy recommendations. (1) Promote systematic thinking in the related departments and strengthen multi-departmental cooperation. Sectors related to climate and development in China should incorporate health perspectives into their policymaking and actions, demonstrating WHO’s and President Xi Jinping’s so-called health-in-all-policies principle. (2) Include clear goals and timelines for climate-related health impact assessments and health adaptation plans at both the national and the regional levels in the National Climate Change Adaptation Strategy for 2035. (3) Strengthen China’s climate mitigation actions and ensure that health is included in China’s pathway to carbon neutrality. By promoting investments in zero-carbon technologies and reducing fossil fuel subsidies, the current rebounding trend in carbon emissions will be reversed and lead to a healthy, low-carbon future. (4) Increase awareness of the linkages between climate change and health at all levels. Health professionals, the academic community, and traditional and new media should raise the awareness of the public and policymakers on the important linkages between climate change and health.</p

Editorial of the Special Issue of the 4th International Symposium on Plant Growth Modeling, Simulation, Visualization and Applications (PMA’12)

International audienc

Implant Stiffness and Peri-Prosthetic Bone Changes in the Rat Model

Clinically, decreased bone content surrounding implants, renewed pain and implant loosening lead to revision surgeries following fracture fixation and joint replacement. A key reason for this phenomenon is stress shielding by Wolff’s law where the high stiffness of the implant materials used results in under loading and resorption of the surrounding bone. What remains to be understood however is how implants of increased stiffness affect bone structure, mechanical properties and biology. To study these effects, an in vitro proof of concept was first conducted in which bone loads and three point bending stiffnesses were shown to increase with increased implant stiffness. Subsequently, 1.1 mm implants with roughened ends were made from nitinol, titanium and stainless steel Kirschner wires. Finally, an in vivo study was conducted on rats in which femora were either left intact, operated on or operated on with a nitinol, titanium or stainless steel wire inserted to evaluate the interrelated effects of bone remodelling.It was discovered that both surgery and implantation negatively affect bone length and isthmus with surgical trauma, implant composition and implant stiffness identified as key factors associated with altered growth plate activity as well as bone remodelling towards and into the intramedullary canal. Similarly, decreased trabecular bone presence and structure were noted however natural aging, surgical trauma and implant material properties all impacted the degree of change to trabecular architecture. Cortical bone structure was also affected with enhanced regions of empty osteocytes and increased periosteal bone deposition dependent upon surgery and implant properties although natural increases in porosity were also observed. Nanoindentation results further indicated the mechanical loads placed on the bone after surgery resulted in changes in bone stiffness at a localised, region based level with respect to time. This was true even for non-implanted contralateral limbs. From the findings presented, it was determined that bone remodelling did not only follow Wolff’s law and instead suggest that remodelling is complex and cannot be simply linearly related to implant stiffness. This study therefore supports the need for more complex bone remodelling models of existing implants and for more implant material research

China Controlled Environment Agriculture---- Sci. &amp; Tech. ( WWW.CHINACEAST.COM)

A fast algorithm for calculating stem and branch radial growth of a tree with substructure approac

Multi-parameter joint optimization for double-strip high-speed pantographs to improve pantograph-catenary interaction quality

The significant increase in speed of high-speed train will cause the dynamic contact force of the pantograph-catenary system to fluctuate more severely, which poses a challenge to the study of the pantograph-catenary relationship and the design of high-speed pantographs. Good pantograph-catenary coupling quality is the essential condition to ensure safe and efficient operation of high-speed train, stable and reliable current collection, and reduction in the wear of contact wires and pantograph contact strips. Among them, the dynamic parameters of high-speed pantographs are crucial to pantograph-catenary coupling quality. With the reduction of the standard deviation of the pantograph-catenary contact force as the optimization goal, multi-parameter joint optimization designs for the high-speed pantograph with two contact strips at multiple running speeds are proposed. Moreover, combining the sensitivity analysis at the optimal solutions, with the parameters and characteristics of in-service DSA380 high-speed pantograph, the optimization proposal of DSA380 was given

Analytical model for the design of permeable reactive barriers considering solute transport in a dual-domain system

A permeable reactive barrier (PRB) is an effective groundwater in situ remediation technology, and the design methods used for PRBs are significant in ensuring that they meet remediation goals. Steady-state analytical solutions are an effective tool to provide conservative and simple design methods. A steady-state analytical solution is proposed to describe organic contaminant transport through the PRB and aquifer in a PRB and cut-off wall system. The proposed analytical solution may serve as an effective tool to provide conservative and simple design methods. The shape factor (S ) is introduced at the PRB-aquifer interface to investigate the effects of a PRB’s layout forms on its performance. The results show that the relative contaminant concentration at the point of compliance for a PRB with S=8 is 11 orders of magnitude larger than that without considering the shape factor. Effects of degradation, dispersion, and advection on PRB design are subjected to dimensionless analysis. Dimensionless analysis shows that degradation plays a key role in decreasing contaminant concentration in the PRB. In addition, increasing advection may promote contaminant transport from the source to the aquifer. Simplified solutions to estimate PRB thickness and source remediation time are derived for the practical design and performance evaluation of the PRB system

Hyaluronic acid modified MPEG-b-PAE block copolymer aqueous micelles for efficient ophthalmic drug delivery of hydrophobic genistein

The ophthalmic drug delivery is a challenge in the clinical treatment of ocular diseases. The traditional drug administration usually shows apparent limitations, such as the low bioavailability from the reason of low penetration of the cornea and the short survival time of drug in the eyes. To overcome these shortcomings, we propose an amphiphilic polymer micelle modified with hyaluronic acid (HA) for high efficient ophthalmic delivery of genistein, a widely used hydrophobic drug for treatment of ocular angiogenesis. The MPEG-b-PAE copolymer was synthesized by the Michael addition reaction, and the final drug carrier MPEG-b-PAE-g-HA was obtained by the process of esterification. Then, genistein was packaged in this drug carrier, getting the final micelles with size of about 84.5 nm. The cell viability tests showed that the micelles take no obvious cytotoxicity to the human cornea epithelium cells. The functionalities of drug slow release and cornea penetration ability were demonstrated in a series ex vivo experiments. Further, the vascular inhibition test illustrated that the micelles could significantly inhibit the angiogenesis of human umbilical vein endothelial cells. These results indicate that the constructed polymer has high feasibility to be used as drug carrier in the treatment of ocular diseases