RESUMEN
Previous research has demonstrated the feasibility of repairing nerve defects through acellular allogeneic nerve grafting with bone marrow mesenchymal stem cells. However, adult tissue-derived mesenchymal stem cells encounter various obstacles, including limited tissue sources, invasive acquisition methods, cellular heterogeneity, purification challenges, cellular senescence, and diminished pluripotency and proliferation over successive passages. In this study, we used induced pluripotent stem cell-derived mesenchymal stem cells, known for their self-renewal capacity, multilineage differentiation potential, and immunomodulatory characteristics. We used induced pluripotent stem cell-derived mesenchymal stem cells in conjunction with acellular nerve allografts to address a 10 mm-long defect in a rat model of sciatic nerve injury. Our findings reveal that induced pluripotent stem cell-derived mesenchymal stem cells exhibit survival for up to 17 days in a rat model of peripheral nerve injury with acellular nerve allograft transplantation. Furthermore, the combination of acellular nerve allograft and induced pluripotent stem cell-derived mesenchymal stem cells significantly accelerates the regeneration of injured axons and improves behavioral function recovery in rats. Additionally, our in vivo and in vitro experiments indicate that induced pluripotent stem cell-derived mesenchymal stem cells play a pivotal role in promoting neovascularization. Collectively, our results suggest the potential of acellular nerve allografts with induced pluripotent stem cell-derived mesenchymal stem cells to augment nerve regeneration in rats, offering promising therapeutic strategies for clinical translation.
RESUMEN
Predicting changes in future land use and farmland production potential (FPP) within the context of shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs) is crucial for devising sustainable land use strategies that balance agricultural production and ecological conservation. Therefore, the Huangshui Basin (HSB) in the northeast Qinghai-Tibet Plateau is taken as the study area, and a LUCC-Plus-FPP (LPF) coupling framework based on the SSP-RCP scenarios is proposed to evaluate future land use patterns and FPP changes. On the basis of the predictions of land use changes from 2020 to 2070, the trade-offs in grain production resulting from bivariate changes in farmland and FPP under future scenarios are analyzed. The results indicate that the model has a high simulation accuracy for land use types, with an overall accuracy of 0.98, a kappa coefficient of 0.97, and a figure of merit value of 0.21. Under the SSP245 and SSP585 scenarios, built-up land increases significantly, by approximately 45.89 %. Farmland and grassland conversions contribute the most to increased built-up land. Farmland area consistently decreases by approximately 5 % across all scenarios. The protection of farmland in the study area is difficult to undertake and thus requires much attention. Moreover, under the SSP126 scenario, the FPP of most districts is greater than that in 2020, and the average FPP of the HSB from 2030 to 2070 is greater than that in 2020. In the SSP585 scenario, by 2070, the average FPP of all districts decreases to different degrees compared with that in 2020. Furthermore, the compensated farmland quantities and average FPPs under all the scenarios are significantly lower than the amount of occupied farmland. The results provide a theoretical foundation and data support for farmland protection decision-making and layout optimization in the Qinghai-Tibet Plateau.
RESUMEN
BACKGROUND: A favorable regenerative microenvironment is essential for peripheral nerve regeneration. Neural tissue-specific extracellular matrix (ECM) is a natural material that helps direct cell behavior and promote axon regeneration. Both bone marrow-derived mesenchymal stem cells (BMSCs) and adipose-derived mesenchymal stem cells (ADSCs) transplantation are effective in repairing peripheral nerve injury (PNI). However, there is no study that characterizes the in vivo microenvironmental characteristics of these two MSCs for the early repair of PNI when combined with neural tissue-derived ECM materials, i.e., acellular nerve allograft (ANA). METHODS: In order to investigate biological characteristics, molecular mechanisms of early stage, and effectiveness of ADSCs- or BMSCs-injected into ANA for repairing PNI in vivo, a rat 10 mm long sciatic nerve defect model was used. We isolated primary BMSCs and ADSCs from bone marrow and adipose tissue, respectively. First, to investigate the in vivo response characteristics and underlying molecular mechanisms of ANA combined with BMSCs or ADSCs, eighty-four rats were randomly divided into three groups: ANA group, ANA+BMSC group, and ANA+ADSC group. We performed flow cytometry, RT-PCR, and immunofluorescence staining up to 4 weeks postoperatively. To further elucidate the underlying molecular mechanisms, changes in long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs) were systematically investigated using whole transcriptome sequencing. We then constructed protein-protein interaction networks to find 10 top ranked hub genes among differentially expressed mRNAs. Second, in order to explore the effectiveness of BMSCs and ADSCs on neural tissue-derived ECM materials for repairing PNI, sixty-eight rats were randomized into four groups: ANA group, ANA+BMSC group, ANA+ADSC group, and AUTO group. In the ANA+BMSC and ANA+ADSC groups, ADSCs/BMSCs were equally injected along the long axis of the 10-mm ANA. Then, we performed histological and functional assessments up to 12 weeks postoperatively. RESULTS: The results of flow cytometry and RT-PCR showed that ANA combined with BMSCs exhibited more significant immunomodulatory effects, as evidenced by the up-regulation of interleukin (IL)-10, down-regulation of IL-1ß and tumor necrosis factor-alpha (TNF-α) expression, promotion of M1-type macrophage polarization to M2-type, and a significant increase in the number of regulatory T cells (Tregs). ANA combined with ADSCs exhibited more pronounced features of pro-myelination and angiogenesis, as evidenced by the up-regulation of myelin-associated protein gene (MBP and MPZ) and angiogenesis-related factors (TGF-ß, VEGF). Moreover, differentially expressed genes from whole transcriptome sequencing results further indicated that ANA loaded with BMSCs exhibited notable immunomodulatory effects and ANA loaded with ADSCs was more associated with angiogenesis, axonal growth, and myelin formation. Notably, ANA infused with BMSCs or ADSCs enhanced peripheral nerve regeneration and motor function recovery with no statistically significant differences. CONCLUSIONS: This study revealed that both ANA combined with BMSCs and ADSCs enhance peripheral nerve regeneration and motor function recovery, but their biological characteristics (mainly including immunomodulatory effects, pro-vascular regenerative effects, and pro-myelin regenerative effects) and underlying molecular mechanisms in the process of repairing PNI in vivo are different, providing new insights into MSC therapy for peripheral nerve injury and its clinical translation.
Asunto(s)
Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas , Regeneración Nerviosa , Traumatismos de los Nervios Periféricos , Ratas Sprague-Dawley , Ingeniería de Tejidos , Animales , Ratas , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/citología , Ingeniería de Tejidos/métodos , Traumatismos de los Nervios Periféricos/terapia , Traumatismos de los Nervios Periféricos/metabolismo , Trasplante de Células Madre Mesenquimatosas/métodos , Nervio Ciático/lesiones , Nervio Ciático/metabolismo , Masculino , Tejido Adiposo/citología , Tejido Adiposo/metabolismoRESUMEN
Peripheral nerve injury (PNI) poses a significant public health issue, often leading to muscle atrophy and persistent neuropathic pain, which can drastically impact the quality of life for patients. Electrical stimulation represents an effective and non-pharmacological treatment to promote nerve regeneration. Yet, the postoperative application of electrical stimulation remains a challenge. Here, we propose a fully biodegradable, self-powered nerve guidance conduit (NGC) based on dissolvable zinc-molybdenum batteries. The conduit can offer topographic guidance for nerve regeneration and deliver sustained electrical cues between both ends of a transected nerve stump, extending beyond the surgical window. Schwann cell proliferation and adenosine triphosphate (ATP) production are enhanced by the introduction of the zinc-molybdenum batteries. In rodent models with 10-mm sciatic nerve damage, the device effectively enhances nerve regeneration and motor function recovery. This study offers innovative strategies for creating biodegradable and electroactive devices that hold important promise to optimize therapeutic outcomes for nerve regeneration.
Asunto(s)
Regeneración Nerviosa , Traumatismos de los Nervios Periféricos , Nervio Ciático , Zinc , Animales , Traumatismos de los Nervios Periféricos/terapia , Zinc/química , Nervio Ciático/fisiología , Nervio Ciático/lesiones , Ratas , Suministros de Energía Eléctrica , Molibdeno/química , Células de Schwann , Ratas Sprague-Dawley , Humanos , Regeneración Tisular Dirigida/instrumentación , Regeneración Tisular Dirigida/métodos , Técnicas Biosensibles , Implantes AbsorbiblesRESUMEN
Optoelectronic neural interfaces can leverage the photovoltaic effect to convert light into electrical current, inducing charge redistribution and enabling nerve stimulation. This method offers a non-genetic and remote approach for neuromodulation. Developing biodegradable and efficient optoelectronic neural interfaces is important for achieving transdermal stimulation while minimizing infection risks associated with device retrieval, thereby maximizing therapeutic outcomes. We propose a biodegradable, flexible, and miniaturized silicon-based neural interface capable of transdermal optoelectronic stimulation for neural modulation and nerve regeneration. Enhancing the device interface with thin-film molybdenum significantly improves the efficacy of neural stimulation. Our study demonstrates successful activation of the sciatic nerve in rodents and the facial nerve in rabbits. Moreover, transdermal optoelectronic stimulation accelerates the functional recovery of injured facial nerves.
Asunto(s)
Regeneración Nerviosa , Nervio Ciático , Animales , Conejos , Regeneración Nerviosa/fisiología , Regeneración Nerviosa/efectos de los fármacos , Nervio Ciático/fisiología , Nervio Facial/fisiología , Nervios Periféricos/fisiología , Masculino , Ratas , Silicio/química , Ratas Sprague-Dawley , Estimulación EléctricaRESUMEN
Curbing the continuous abandonment of large areas of farmland is important for meeting the global food demand and promoting agricultural and rural development. Accurate identification is the key to the effective management and utilization of abandoned farmland. The identification of abandoned land based on a long time series of remote sensing data has become rapid and effective. Therefore, a set of training and test datasets generated from invariant samples and reference sample sets is established in this paper. On this basis, the Google Earth Engine (GEE) is used to classify Landsat and Sentinel high-precision long-term remote sensing images from 2000 to 2022. In addition, a change detector based on the sliding window algorithm is proposed to extract abandoned farmland in the Huangshui Basin from 2002 to 2020, and the intensity, trend, frequency, reclamation rate and utilization efficiency are analyzed. The results revealed that the OA of land use classification in the Huangshui Basin from 2000 to 2022 was between 0.852 and 0.91, and the kappa coefficient was between 0.822 and 0.89, indicating a good classification effect. From 2002 to 2020, the accumulated abandoned farmland area in the Huangshui Basin continued to increase, showing a fluctuating upward trend, and the phenomenon of farmland abandonment and reclamation occurs repeatedly in some areas. From the overall distribution, the abandoned area gradually increased from the central region to the southeast. With the passage of time, the amount of abandoned farmland in the valley increased gradually, and the abandoned area was transferred from the high mountains to the valley area. The average annual abandonment rate of supplementary farmland was 50.45%, which was much greater than that of basic farmland. Most of the supplementary farmland could not be effectively and judiciously used, and the utilization efficiency was low. The research results provide data support for the reuse of abandoned farmland in ecologically fragile plateau areas, the formulation of targeted strategies, the implementation of timely adjustments, and the establishment of new ideas and methods for the accurate identification of abandoned farmland.
Asunto(s)
Agricultura , Suelo , Granjas , Tibet , Bosques , ChinaRESUMEN
It is a common understanding that the 2019 coronavirus pandemic (COVID-19) significantly harmed mental health. However, findings on changes in overall life satisfaction have been mixed and inconclusive. To address this puzzling phenomenon, we draw upon the domain-specific perspective of well-being and research on catastrophe compassion and propose that the pandemic can have opposing effects on mental health and communal satisfaction, which then differently relate to people's overall life satisfaction. Longitudinal analyses of the Household, Income and Labour Dynamics (HILDA) Survey of Australia (N = 12,093) showed that while there was a greater decrease in mental health in the first COVID-19 pandemic year (2019-2020) than in the previous years (2017-2019), an increase in communal satisfaction also occurred, demonstrating a potential silver lining effect of the pandemic on people's satisfaction with family, community, and neighborhood. Moreover, consistent with socioemotional selectivity theory, changes in mental health, communal satisfaction, and life satisfaction were related to age, such that older adults generally reported less harmful and more beneficial psychological changes. We further found that age was associated with stronger associations of mental health and communal satisfaction with life satisfaction during the pandemic year. Overall, our findings speak to the importance of communal life in life satisfaction during the pandemic and age-related differences in the process, shedding light on the need to devise customized support to address inequalities in pandemic effects on public well-being. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Asunto(s)
COVID-19 , Humanos , Anciano , Pandemias , Emociones , Satisfacción Personal , Australia/epidemiologíaRESUMEN
Peripheral nerve injuries (PNI) can lead to mitochondrial dysfunction and energy depletion within the affected microenvironment. The objective is to investigate the potential of transplanting mitochondria to reshape the neural regeneration microenvironment. High-purity functional mitochondria with an intact structure are extracted from human umbilical cord-derived mesenchymal stem cells (hUCMSCs) using the Dounce homogenization combined with ultracentrifugation. Results show that when hUCMSC-derived mitochondria (hUCMSC-Mitos) are cocultured with Schwann cells (SCs), they promote the proliferation, migration, and respiratory capacity of SCs. Acellular nerve allografts (ANAs) have shown promise in nerve regeneration, however, their therapeutic effect is not satisfactory enough. The incorporation of hUCMSC-Mitos within ANAs has the potential to remodel the regenerative microenvironment. This approach demonstrates satisfactory outcomes in terms of tissue regeneration and functional recovery. Particularly, the use of metabolomics and bioenergetic profiling is used for the first time to analyze the energy metabolism microenvironment after PNI. This remodeling occurs through the enhancement of the tricarboxylic acid cycle and the regulation of associated metabolites, resulting in increased energy synthesis. Overall, the hUCMSC-Mito-loaded ANAs exhibit high functionality to promote nerve regeneration, providing a novel regenerative strategy based on improving energy metabolism for neural repair.
Asunto(s)
Células Madre Mesenquimatosas , Tejido Nervioso , Traumatismos de los Nervios Periféricos , Humanos , Nervio Ciático , Células de Schwann , Traumatismos de los Nervios Periféricos/terapia , Matriz Extracelular , Regeneración Nerviosa/fisiologíaRESUMEN
Research on mentoring programs has portrayed them almost exclusively beneficial for newcomer retention. Drawing from the social cognitive model of career management and the boundaryless career perspective, we depart from this predominant view and examine the "double-edged sword" effects of career support mentoring on newcomer turnover. We propose that career support mentoring received by newcomers is likely to elicit both internal proactive socialization and external career self-management, which act as countervailing forces driving newcomer turnover in opposite directions (i.e., the retention pathway and the unintended detrimental pathway). We further propose that the organizational role of the mentor-supervisor versus nonsupervisor-is critical in determining which pathway prevails. We conducted two multiwave newcomer studies to test our hypotheses. In Study 1 (N = 495), we found that received career support mentoring was associated with lower newcomer turnover probability through the serial mediation of internal proactive socialization and perceived internal marketability but higher newcomer turnover probability through the serial mediation of external career self-management and perceived external marketability. In Study 2 (N = 193), we found that received career support mentoring was associated with lower newcomer turnover intention through the serial mediation of internal career advancement expectation and internal proactive socialization but higher newcomer turnover intention through the serial mediation of external career advancement expectation and external career self-management. In both studies, the unintended detrimental pathway was significant only when a newcomer's mentor was not a supervisor. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
RESUMEN
Peripheral nerve injury represents one of the most common types of traumatic damage, severely impairing motor and sensory functions, and posttraumatic nerve regeneration remains a major challenge. Electrical cues are critical bioactive factors that promote nerve regrowth, and bioartificial scaffolds incorporating conductive materials to enhance the endogenous electrical field have been demonstrated to be effective. The utilization of fully biodegradable scaffolds can eliminate material residues, and circumvent the need for secondary retrieval procedures. Here, a fully bioresorbable and conductive nerve scaffold integrating N-type silicon (Si) membranes is proposed, which can deliver both structural guidance and electrical cues for the repair of nerve defects. The entire scaffold is fully biodegradable, and the introduction of N-type Si can significantly promote the proliferation and production of neurotrophic factors of Schwann cells and enhance the calcium activity of dorsal root ganglion (DRG) neurons. The conductive scaffolds enable accelerated nerve regeneration and motor functional recovery in rodents with sciatic nerve transection injuries. This work sheds light on the advancement of bioresorbable and electrically active materials to achieve desirable neural interfaces and improved therapeutic outcomes, offering essential strategies for regenerative medicine.
Asunto(s)
Traumatismos de los Nervios Periféricos , Silicio , Humanos , Implantes Absorbibles , Neuronas , Regeneración Nerviosa/fisiología , Traumatismos de los Nervios Periféricos/terapia , Ganglios Espinales , Nervio Ciático/fisiología , Andamios del Tejido/químicaRESUMEN
Graft-host mechanical mismatch has been a longstanding issue in clinical applications of synthetic scaffolds for soft tissue regeneration. Although numerous efforts have been devoted to resolve this grand challenge, the regenerative performance of existing synthetic scaffolds remains limited by slow tissue growth (comparing to autograft) and mechanical failures. We demonstrate a class of rationally designed flexible network scaffolds that can precisely replicate nonlinear mechanical responses of soft tissues and enhance tissue regeneration via reduced graft-host mechanical mismatch. Such flexible network scaffold includes a tubular network frame containing inversely engineered curved microstructures to produce desired mechanical properties, with an electrospun ultrathin film wrapped around the network to offer a proper microenvironment for cell growth. Using rat models with sciatic nerve defects or Achilles tendon injuries, our network scaffolds show regenerative performances evidently superior to that of clinically approved electrospun conduit scaffolds and achieve similar outcomes to autologous nerve transplantation in prevention of target organ atrophy and recovery of static sciatic index.
Asunto(s)
Biomimética , Películas Cinematográficas , Animales , Ratas , Proliferación Celular , Atrofia , Ciclo CelularRESUMEN
Land reclamation is a long-term, dynamic process; postreclamation monitoring and management are particularly important, and the use of remote sensing technology is a good way to conduct ecological quality monitoring and evaluations. In this study, we fused ZhuHai-1 and Landsat 8 data; selected the best band combinations to calculate ecological quality indicators such as the inverted red-edge chlorophyll index, modified soil moisture monitoring index, normalized difference built-up and soil index and land surface temperature; and constructed the fusion remote sensing ecological index to monitor the ecological restoration effect of the reclaimed area in Pingshuo, China. The results showed that the inverted red-edge chlorophyll index and modified soil moisture monitoring index had positive contributions, the normalized difference built-up and soil index had a low impact on the ecological quality of the study area, and the land surface temperature had a negative effect on ecological quality. The environment of the reclaimed area was better than that of the surrounding areas where these areas were affected by mining. The mean value of the fusion remote sensing ecological index showed a trend of "rising first, then falling" with increasing reclamation time. The ecological quality of the reclaimed area was best in areas with 20-22 years of reclamation time. The ecological condition of the area has been declining for 25 years or more of reclamation, so it is suitable to apply artificial intervention to ensure good ecological quality. The use of remote sensing technology for monitoring the effects of ecological restoration can provide a reference basis for the targeted and accurate implementation of land reclamation management measures.
RESUMEN
Deferoxamine (DFO) is a potent iron chelator for clinical treatment of various diseases. Recent studies have also shown its potential to promote vascular regeneration during peripheral nerve regeneration. However, the effect of DFO on the Schwann cell function and axon regeneration remains unclear. In this study, we investigated the effects of different concentrations of DFO on Schwann cell viability, proliferation, migration, expression of key functional genes, and axon regeneration of dorsal root ganglia (DRG) through a series of in vitro experiments. We found that DFO improves Schwann cell viability, proliferation, and migration in the early stages, with an optimal concentration of 25 µM. DFO also upregulates the expression of myelin-related genes and nerve growth-promoting factors in Schwann cells, while inhibiting the expression of Schwann cell dedifferentiation genes. Moreover, the appropriate concentration of DFO promotes axon regeneration in DRG. Our findings demonstrate that DFO, with suitable concentration and duration of action, can positively affect multiple stages of peripheral nerve regeneration, thereby improving the effectiveness of nerve injury repair. This study also enriches the theory of DFO promoting peripheral nerve regeneration and provides a basis for the design of sustained-release DFO nerve grafts.
Asunto(s)
Regeneración Nerviosa , Traumatismos de los Nervios Periféricos , Humanos , Regeneración Nerviosa/fisiología , Ganglios Espinales , Axones , Deferoxamina/metabolismo , Deferoxamina/farmacología , Células Cultivadas , Células de Schwann/metabolismo , Factores de Crecimiento Nervioso/metabolismo , Traumatismos de los Nervios Periféricos/metabolismoRESUMEN
Given the advantages of high energy density and easy deployment, biodegradable primary battery systems remain as a promising power source to achieve bioresorbable electronic medicine, eliminating secondary surgeries for device retrieval. However, currently available biobatteries are constrained by operational lifetime, biocompatibility, and biodegradability, limiting potential therapeutic outcomes as temporary implants. Herein, we propose a fully biodegradable primary zinc-molybdenum (Zn-Mo) battery with a prolonged functional lifetime of up to 19 days and desirable energy capacity and output voltage compared with reported primary Zn biobatteries. The Zn-Mo battery system is shown to have excellent biocompatibility and biodegradability and can significantly promote Schwann cell proliferation and the axonal growth of dorsal root ganglia. The biodegradable battery module with 4 Zn-Mo cells in series using gelatin electrolyte accomplishes electrochemical generation of signaling molecules (nitric oxide, NO) that can modulate the behavior of the cellular network, with efficacy comparable with that of conventional power sources. This work sheds light on materials strategies and fabrication schemes to develop high-performance biodegradable primary batteries to achieve a fully bioresorbable electronic platform for innovative medical treatments that could be beneficial for health care.
Asunto(s)
Suministros de Energía Eléctrica , Zinc , Electrónica , Gelatina , Proliferación Celular , Molibdeno , Óxido NítricoRESUMEN
Autologous nerve grafting serves is considered the gold standard treatment for peripheral nerve defects; however, limited availability and donor area destruction restrict its widespread clinical application. Although the performance of allogeneic decellularized nerve implants has been explored, challenges such as insufficient human donors have been a major drawback to its clinical use. Tissue-engineered neural regeneration materials have been developed over the years, and researchers have explored strategies to mimic the peripheral neural microenvironment during the design of nerve catheter grafts, namely the extracellular matrix (ECM), which includes mechanical, physical, and biochemical signals that support nerve regeneration. In this study, polycaprolactone/silk fibroin (PCL/SF)-aligned electrospun material was modified with ECM derived from human umbilical cord mesenchymal stem cells (hUMSCs), and a dual-bionic nerve regeneration material was successfully fabricated. The results indicated that the developed biomimetic material had excellent biological properties, providing sufficient anchorage for Schwann cells and subsequent axon regeneration and angiogenesis processes. Moreover, the dual-bionic material exerted a similar effect to that of autologous nerve transplantation in bridging peripheral nerve defects in rats. In conclusion, this study provides a new concept for designing neural regeneration materials, and the prepared dual-bionic repair materials have excellent auxiliary regenerative ability and further preclinical testing is warranted to evaluate its clinical application potential.
RESUMEN
Inflammation is part of the natural healing response, but persistent inflammatory events tend to contribute to pathology changes of tendon or ligament. Phenotypic switching of macrophages within the inflammatory niche is crucial for tendon healing. One viable strategy to improve the functional and biomechanical properties of ruptured tendons is to modulate the transition from inflammatory to regenerative signals during tendon regeneration at the site of injury. Here, we developed a tendon repair scaffold made of biodegradable polycaprolactone by electrospinning, which was modified to deliver Wnt3a protein and served as an implant to improve tendon healing in a rat model of Achilles tendon defect. During the in vitro study, Wnt3a protein promoted the polarization of M2 macrophages. In the in vivo experiment, Wnt3a scaffold promoted the early recruitment and counting curve of macrophages and increased the proportion of M2 macrophages. Achilles function index and mechanical properties showed that the implantation effect of the Wnt3a group was better than that of the control group. We believe that this type of scaffold can be used to repair tendon defects. This work highlights the beneficial role of local delivery of biological factors in directing inflammatory responses toward regenerative strategies in tendon healing.
RESUMEN
This study examines the long-term effect of a pandemic on a crucial human capital decision, namely college major choice. Using China's 2008-2016 major-level National College Entrance Examination (Gaokao) entry grades, we find that the 2003 severe acute respiratory syndrome (SARS) had a substantial deterrent effect on the choice of majoring in medicine among high school graduates who experienced the pandemic in their childhood. In provinces with larger intensities of SARS impact, medical majors become less popular as the average Gaokao grades of enrolled students decline. Further evidence from a nationally representative survey shows that the intensity of the SARS impact significantly decreases children's aspirations to pursue medical occupations, but does not affect their parents' expectations for their children to enter the medical profession. Our discussion on the effect mechanism suggests that the adverse influence of SARS on the popularity of medical majors likely originates from students' childhood experiences.
Asunto(s)
Medicina , Síndrome Respiratorio Agudo Grave , Niño , Humanos , Síndrome Respiratorio Agudo Grave/epidemiología , Pandemias , Selección de Profesión , Estudiantes , China/epidemiologíaRESUMEN
Following peripheral nerve injury (PNI), Wallerian degeneration (WD) in the distal stump can generate a microenvironment favorable for nerve regeneration. Brief low-frequency electrical stimulation (ES) is an effective treatment for PNI, but the mechanism underlying its effect on WD remains unclear. Therefore, we hypothesized that ES could enhance nerve regeneration by accelerating WD. To verify this hypothesis, we used a rat model of sciatic nerve transection and provided ES at the distal stump of the injured nerve. The injured nerve was then evaluated after 1, 4, 7, 14 and 21 days post injury (dpi). The results showed that ES significantly promoted the degeneration and clearance of axons and myelin, and the dedifferentiation of Schwann cells. It upregulated the expression of BDNF and NGF and increased the number of monocytes and macrophages. Through transcriptome sequencing, we systematically investigated the effect of ES on the molecular processes involved in WD at 4 dpi. Evaluation of nerves bridged using silicone tubing after transection showed that ES accelerated early axonal and vascular regeneration while delaying gastrocnemius atrophy. These results demonstrate that ES promotes nerve regeneration by accelerating WD and upregulating the expression of neurotrophic factors.
Asunto(s)
Traumatismos de los Nervios Periféricos , Neuropatía Ciática , Ratas , Animales , Traumatismos de los Nervios Periféricos/metabolismo , Degeneración Walleriana/terapia , Degeneración Walleriana/patología , Neuropatía Ciática/patología , Nervio Ciático/metabolismo , Células de Schwann/metabolismo , Axones/metabolismo , Regeneración Nerviosa/fisiología , Estimulación EléctricaRESUMEN
Osteonecrosis of the femoral head (ONFH) is a progressive disease that often necessitates hip replacement if hip preservation therapy fails. ONFH places a heavy economic burden and severe psychological pressure on patients. At present, ONFH is treated by either surgical or non-surgical methods. In clinical practice, stem cells combined with surgery has achieved some positive results, but many problems remain to be resolved. Exosomes are small vesicles of 30-150 nm, which are rich in various nucleic acids, proteins, and small molecules depending on the cells from which they are derived. A growing number of studies have found that exosomes play an important role in tissue damage repair. In comparison with stem cells, exosomes have lower immunogenicity. Also, exosomes can promote cell proliferation and inhibit tumor growth. In addition, exosomes can also be used as natural carriers of drugs. Many studies have shown that exosomes have therapeutic effects in hormone-induced ONFH. Exosomes have the effect of promoting vascular regeneration and show good application prospects in ONFH. Here, we present a review of studies on the application of exosomes in ONFH to provide a reference for future research.