Shallow planting of the rice seedlings is an important factor for getting high yield as it can increase the effective tillers on the lownode of the stem. The 2 ZB-79 shallow rice seedling transplanter combined the adv...Shallow planting of the rice seedlings is an important factor for getting high yield as it can increase the effective tillers on the lownode of the stem. The 2 ZB-79 shallow rice seedling transplanter combined the advantages of shallow planting of the seedling-casting rice transplanter and orderly planting of the traditional rice transplanter. The principle of this kind of machine is firstly to cut the standardization nursery rice seedlings with rug soil into many small pieces,and then to plant the small pieces composed of pot soil and some seedlings on it to the field surface in order,only shallowly planted on the very top part of paddy soil. Not only it can keep the performance of planting shallowly and orderly,but also simplify many mechanisms for transition,separation,and plantation of rice seedlings. It is a new type of rice seedling transplanter called laying-type up to now to get higher efficiency when working and higher yield for rice production. This paper will introduce its developing results and analyze the comparative experiments.展开更多
To meet the operational criteria for mechanical transplanting of young seedlings in paddy-straw-made bowl-seedling trays,a new seedling needle and seedling pushing device have been developed.This paper presents the de...To meet the operational criteria for mechanical transplanting of young seedlings in paddy-straw-made bowl-seedling trays,a new seedling needle and seedling pushing device have been developed.This paper presents the design process and analyzes the effects of key parameters,including the angle of inclination of flat edge,width of flat edge,length of flat edge,wedge angle,and width of seedling pushing device for new seedling needle and seedling pushing device.Optimization parameters of new seedling needle and seedling pushing device have been validated by orthogonal experiments.The optimized values,such as a flat edge inclination angle of 35°,a flat edge width of 10 mm,a flat edge length of 64 mm,a wedge angle of 60°,and a seedling-pushing device width of 8 mm,satisfy the operational requirements for mechanically transplanting young seedlings in paddy-straw-made bowl seedling trays.The results demonstrate significant improvements in transplanting efficiency within Chinese agricultural systems.展开更多
In order to improve the automatic sorting and transplanting of tray-seedling and reduce labors strength,a new sorting transplanter was designed.According to the feature of normal seedling tray and manual grading metho...In order to improve the automatic sorting and transplanting of tray-seedling and reduce labors strength,a new sorting transplanter was designed.According to the feature of normal seedling tray and manual grading method,the mechanical sorting procedure was defined.The key parts of sorting transplanter are as follows:an efficient transfer mechanism with aerodynamic buffer,a seedling identifying and measuring unit based on linear-structured vision,the extendible multi-grasper with wireless technology and the system controller.The experiments were conducted and showed that the transplanting success rate was 90.0% on the tray of 6×12 holes under the speed of 700 cycles per hour.The vision unit’s failed identifying rate for the superior pepper seedlings on five different trays was less than 10%,and the measurement error of seedling height was about 5 mm.展开更多
An automatic feeding mechanism consisting of a timing shaft,an actuating device and a clutch for feeding paper pot seedlings from a horizontal slat type chain conveyor to a horizontal pusher type chain conveyor of a v...An automatic feeding mechanism consisting of a timing shaft,an actuating device and a clutch for feeding paper pot seedlings from a horizontal slat type chain conveyor to a horizontal pusher type chain conveyor of a vegetable transplanter,was developed.The slat type chain conveyor carried the pot seedlings in upright orientation in the form of a rectangular array with each linear array of pot seedlings on a slat.The pusher type chain conveyor received a linear array of pot seedlings and delivered them to the seedling drop tube.Feeding of each linear array of pot seedlings to the pusher type conveyor at appropriate times was done using an automatic feeding mechanism.The laboratory evaluation indicated that the feeding rate of 33 to 50 pot seedlings per minute can be achieved with single set of conveyors.The feeding mechanism also worked effectively under actual field conditions with 98%to 99%of all the pot seedlings,which were properly separated and fed for planting when the forward speed of the vegetable transplanter was 0.9 km/h.The feeding mechanism has the general application of singulating rectangular array of items on the slat type chain conveyor in any industry and machine in motion on a level surface.展开更多
Rice transplanting requires the operator to manipulate the rice transplanter in straight trajectories.Various markers are proposed to help experienced drivers in keeping straightforward and parallel to the previous pa...Rice transplanting requires the operator to manipulate the rice transplanter in straight trajectories.Various markers are proposed to help experienced drivers in keeping straightforward and parallel to the previous path,which are extremely boring in terms of large-scale fields.The objective of this research was to develop an autonomous navigation system that automatically guided a rice transplanter working along predetermined paths in the field.The rice transplanter used in this research was commercially available and originally manually-operated.An automatic manipulating system was developed instead of manual functions including steering,stop,going forward and reverse.A sensor fusion algorithm was adopted to integrate measurements of the Real-Time Kinematic Global Navigation Satellite System(RTK-GNSS)and Inertial Measurement Unit(IMU),and calculate the absolute moving direction under the UTM coordinate system.A headland turning control method was proposed to ensure a robust turning process considering that the rice transplanter featured a small turning radius and a relatively large slip rate at extreme steering angles.Experiments were designed and conducted to verify the performance of the newly developed autonomous navigation system.Results showed that both lateral and heading errors were less than 8 cm and 3 degrees,respectively,in terms of following straight paths.And headland turns were robustly executed according to the required pattern.展开更多
This research aimed to solve current problems in the process of maize transplanting in China such as large labor intensity,low working efficiency and poor quality.On the basis of the structure of a seedling-sprouting ...This research aimed to solve current problems in the process of maize transplanting in China such as large labor intensity,low working efficiency and poor quality.On the basis of the structure of a seedling-sprouting tray made of maize straw and the agronomic requirements of maize production,this study developed a new feeding device for such a sprouting tray,determined the dimensions of the key components in a virtual environment via Solid Edge software and obtained optimal working parameters in combination with Matlab.Some tests on field validation and maize production were conducted as well.The test results showed the importance of the working parameters on an upright degree in descending order(as well as the best working parameters)to be the vertical angle of seedling planting(13.14°),the forward speed of locomotion(0.57 m/s),and the horizontal angle of the seedling box(22.5°).The standard deviation of the field validation was 6.04%,which was within the allowable range to meet the requirements of maize transplanting.Compared with maize transplanting machines(and manual transplanting operations)on the current market,the labor inputs,as well as the rates of spacing and upright degree qualification,omitted planting and the yield using the new feeding device for automatic transplanter with maize straw seedling-sprouting trays increased 0(6.9%),0(3.1%),0(4.5%)and 0(−1.0%),respectively;whereas,the manufacturing cost was reduced by 35.5%.The results can provide a technical basis and reference for subsequent development of automatic transplanters with maize straw seedling-sprouting trays.展开更多
The rotary plug seedling pick-up mechanism for vegetable automatic transplanter is the technical bottleneck to improve the mechanization level of vegetable planting in China.In order to solve the problems of rotary se...The rotary plug seedling pick-up mechanism for vegetable automatic transplanter is the technical bottleneck to improve the mechanization level of vegetable planting in China.In order to solve the problems of rotary seedling pick-up mechanism proposed in previous study,such as low success ratio of seedling pick-up at high speed,and interference between the seedling bowl and the end of the other seedling pick-up arm,a novel kind of rotary seedling pick-up mechanism of planetary gear train with combined type gears of incomplete denatured-eccentric-circular and non-circular gears was proposed.Through kinematic analysis of the seedling pick-up mechanism,the kinematics model was established.The computer-aided analysis and optimization software with human-computer interaction method was developed to realize parameters optimization of the seedling pick-up mechanism.Three-dimensional parametric design system of seedling pick-up mechanisms with combined non-circular gear transmission was developed for mechanism virtual simulation to verify the correctness of theoretical model and design results of the mechanism.The physical prototype of the mechanism was manufactured,and high-speed camera kinematics tests of the mechanism were conducted in the laboratory to study its kinematic characteristics.Laboratory seedling pick-up tests were carried out.The mechanism has the success ratio of seedling pick-up 96.3%without interference during seedling transporting when the rotation speed of the mechanism is 50 r/min and the seedling transplanting efficiency is 100 plants/min per row,showing that the novel mechanism has better working performance than the original one and could be applied in vegetable plug seedling transplanter.展开更多
To improve the precision of deep fertilization of paddy fields,a six-row centralized pneumatic deep precision fertilization device for a rice transplanter was designed.This device included a spiral fertilizer distribu...To improve the precision of deep fertilization of paddy fields,a six-row centralized pneumatic deep precision fertilization device for a rice transplanter was designed.This device included a spiral fertilizer distribution system,centralized pneumatic fertilizer delivery system,an opener system,and a fertilization control system.The centralized airflow distribution method was used in the fertilizer delivery system to ensure that the airflow in each fertilizer pipe was evenly distributed.The rotational speeds of the power take-off(PTO)and fertilizer shaft were measured synchronously using photoelectric sensors and matched proportionately in real-time using PID closed-loop control algorithms to achieve precise fertilization rates at each working speed of the rice transplanter.There were two key considerations in the design of the control system to ensure precise fertilization.Firstly,a photoelectric sensor was used to measure the speed of the PTO;the high rotational speed of the PTO could provide a high signal frequency and improve the precision of the measurement of the transplanter’s working speed.Secondly,the fertilizer shaft speed measurement subprogram was set to sleep for a short period to reduce the vibration caused by the engine.During the tests of pneumatic fertilizer delivery system,single-factor tests on airflow distribution methods were conducted.The results showed that the coefficient of variation of the airflow speed for the centralized airflow distribution method was 1.67%,which was the least among the coefficients of the three distribution methods.In the bench tests,the rotational speeds of the fertilizer shaft were set at 10 r/min,20 r/min,30 r/min,and 40 r/min.The maximum coefficient of variation of the fertilization consistency in different rows was 1.49%at the rotational speed of 20 r/min.The maximum coefficient of variation of the fertilization stability was 2.86%at the rotational speed of 40 r/min,while the average fertilizer amount per lap for each distributor was 26.25 g/r.The results of the dynamic fertilization tests showed that the maximum relative error of the fertilizer distribution amount was 2.00%when the target fertilizer rates were 20,30,and 40 kg/667 m2.The results of the field tests showed that the average relative error of the fertilization amount was 3.53%,which satisfies the design standard.This research provides a reference for optimizing pneumatic fertilizer delivery systems and improving fertilization control systems and other pneumatic precision fertilizer application devices.展开更多
Considering both high efficiency and high seedling standing quality is a significant objective for crop mechanized transplanting.Rape blanket seedling transplanting is an innovative and efficient transplanting techniq...Considering both high efficiency and high seedling standing quality is a significant objective for crop mechanized transplanting.Rape blanket seedling transplanting is an innovative and efficient transplanting technique.However,falling off phenomenon has become a common problem facing rape blanket seedling transplanting fields that causes seedling standing quality decrease and restricts crop growth.In this study,the rape blanket seedling of Ningza-1838 varieties and 35 d of seedling age was taken as the research object.The critical falling off equations of seedling was established by dynamic analysis.Main factors affecting seedling falling off were obtained.The critical value of each factor was calculated which were as follows:the rotation speed of the planting mechanism was 24.6 rad/s,the substrate moisture content was 50.4%and the longitudinal picking seedling quantity was 14.7 mm.Taking the seedling falling off rate as evaluation index,the measured critical value of seedling falling off was determined by high speed photography experiment.Under the condition that substrate moisture content was 55%and the longitudinal seedling quantity was 15 mm,the seedling falling off rate sharply increased when the transplanting mechanism rotation speed was increased from 24 rad/s to 26 rad/s.Under the condition that the rotation speed was 22 rad/s and the longitudinal picking seedling quantity was 15 mm,the seedling falling off rate rapidly decreased when the moisture content was increased from 47%to 53%.When moisture content exceeded 53%,this exhibited no obvious change.Under the condition that the moisture content was 50%and the rotation speed was 22 rad/s,the seedling falling off rate swiftly raised when the longitudinal picking seedling quantity was increased from 14 mm to 17 mm.The experimental results showed that the seedling falling off rate increased significantly near the critical value.The experimental results showed that the seedling falling off rate changed significantly near the critical value.It proved that the model was correct.Response surface experiments with the Box-Behnken design were conducted to determine the optimal combination parameters,which were as follows:substrate moisture content was 56.24%,planting mechanism rotation speed was 22.04 rad/s,and longitudinal picking seedling quantity was 14.91 mm.At this time,the seedling falling off rate was 1.36%,which ensured that seedlings could be transplanted stably under the carrier of seedling needle.The verification test was conducted,and the working parameters were adjusted according to the optimization results in experiment.The results of verification test were highly consistent with the optimization solution.The present study may provide a theoretical method for improving seedling standing quality of rape blanket seedling,and laid a foundation for the popularization and development of rape carpet seedling transplanting.展开更多
The chassis of rice transplanter tends to vibrate severely in the severe working environment,causing a severe effect on the operational performance and driving comfort.In order to avoid this situation,this paper const...The chassis of rice transplanter tends to vibrate severely in the severe working environment,causing a severe effect on the operational performance and driving comfort.In order to avoid this situation,this paper constructs a vibration evaluation system of the rice transplanter and carries out experimental analysis.According to the optimal acceleration sensor placement scheme,a test platform system was designed.Taking the high-speed transplanter chassis as the research object,this study carried out the experiments modal analysis and optimization on the chassis.The three-dimensional model of the transplanting machine chassis established by SolidWorks was imported into ANSYS Workbench for finite element modal simulation analysis.Comparing the two modal analyses,it is found that the results data of the two analysis methods were very close.After optimization,the length x1,the section width x2 and the thickness of the hollow beam x3 of the main load-bearing beam of the frame were as follows:x1=1641.5 mm,x2=26.7 mm,x3=5 mm,respectively.The maximum overshoot of the low-level system was reduced by 28.57%.It has been verified that the vibration of the whole machine has been effectively reduced.展开更多
To improve the low transplanting efficiencies and simplify the complex structures of current automatic transplanters,a mechanical high-speed transplanter for picking plug seedlings that is suitable for planting on pla...To improve the low transplanting efficiencies and simplify the complex structures of current automatic transplanters,a mechanical high-speed transplanter for picking plug seedlings that is suitable for planting on plastic filmswas designed.Themain components were an automatic seedling picking systemand a basket-type planting system,whichwere used for the following processes:automatic picking,planting,soil covering,and suppression of plug seedlings.The performance test was performed on the automatic transplanter with 60-day-old pepper seedlings.The transplanting efficiency was tested at speeds of 40,60,90,and 120 plants·min−1.The results showed that the coefficient of variation(CV)of the plant spacing and the missed transplanting rate increased with the planting frequency,whereas the qualified rate of planting perpendicularity and the qualified rate of planting decreasedwith the increase in the planting frequency.All planting indicesmet the JB/T 102912013 standards.The results of this study showed that the auto-transplanter could performhigh-speed transplanting on the basis of completing the following functions:automatic picking,planting,soil covering,and suppression of plug seedlings.展开更多
The aim of this study was to analyze the effects of the planting distance and depth on the power take-off(PTO)load spectrum of a small riding-type transplanter for the optimal design of the transplanter.To measure loa...The aim of this study was to analyze the effects of the planting distance and depth on the power take-off(PTO)load spectrum of a small riding-type transplanter for the optimal design of the transplanter.To measure load data during actual planting operation,a load measurement system was developed using a torque sensor,a data acquisition system,and an inverter.Field experiments were conducted at four planting distances(26 cm,35 cm,43 cm,and 80 cm)and three planting depths(85 mm,105 mm,and 136 mm)in a field with similar soil conditions.The measured load data were inverted into a load spectrum using rain-flow counting and Smith-Watson-Topper(SWT)methods.The safety factor of a transplanter according to the planting conditions was analyzed using the converted load spectrum and commercial software.The load spectrum for all planting conditions showed torque ratios similar within a high cycle region of 108 to 109.The torque ratio increased when the planting depth increased and planting distance decreased in the low cycle region under less than 108 cycles.The safety factors of the PTO driving gear and the driven gear increased as the planting distance increased at all planting depths.When the planting depth decreased at the same planting distance,the safety factor of the PTO gears increased.The results of this study might provide useful information for a transplanter PTO design considering the working load according to the various planting conditions.展开更多
This paper presents the study reports on evaluating a new transplanting operation by taking into accounts the interactions between soil,plant,and machine in line with the System of Rice Intensification(SRI)practices.T...This paper presents the study reports on evaluating a new transplanting operation by taking into accounts the interactions between soil,plant,and machine in line with the System of Rice Intensification(SRI)practices.The objective was to modify planting claw(kuku-kambing)of a paddy transplanter in compliance with SRI guidelines to determine the best planting spacing(S),seed rate(G)and planting pattern that results in a maximum number of seedling,tillers per hill,and yield.Two separate experiments were carried out in two different paddy fields,one to determine the best planting spacing(S=4 levels:s_(1)=0.16 m×0.3 m,s_(2)=0.18 m×0.3 m,s_(3)=0.21 m×0.3 m,and s_(4)=0.24 m×0.3 m)for a specific planting pattern(row mat or scattered planting pattern),and the other to determine the best combination of spacing with seed rate treatments(G=2 levels:g1=75 g/tray,and g2=240 g/tray).Main SRI management practices such as soil characteristics of the sites,planting depth,missing hill,hill population,the number of seedling per hill,and yield components were evaluated.Results of two-way analysis of variance with three replications showed that spacing,planting pattern and seed rate affected the number of one-seedling in all experiment.It was also observed that the increase in spacing resulted in more tillers and more panicle per plant,however hill population and sterility ratio increased with the decrease in spacing.While the maximum number of panicles were resulted from scattered planting at s_(4)=0.24 m×0.3 m spacing with the seed rate of g1=75 g/tray,the maximum number of one seedling were observed at s_(4)=0.16 m×0.3 m.The highest and lowest yields were obtained from 75 g seeds per tray scattered and 70 g seeds per tray scattered treatment respectively.For all treatments,the result clearly indicates an increase in yield with an increase in spacing.展开更多
The vibration problem during the operation of rice transplanters is the most common phenomenon.In order that the static and dynamic characteristics of the rice transplanter chassis can meet the requirements of more st...The vibration problem during the operation of rice transplanters is the most common phenomenon.In order that the static and dynamic characteristics of the rice transplanter chassis can meet the requirements of more stable operation,the research took the 2ZG-6DK rice transplanter as the research object to carry out a vibration reduction optimization study.In the research,the Pro/Engineer 5.0 software was first used to model the chassis of the rice transplanter.The constructed finite element model was revised by using the structural parameter revision method and the mixed penalty function method.The model was imported into ANSYS Workbench to solve the modal frequency and vibration shape of the rice transplanter chassis.Based on the MAC(modal assurance criterion)criterion,modal tests were carried out to verify the accuracy of the finite element theoretical analysis.Through the analysis of the characteristics of the external excitation frequency,the chassis is structurally optimized to avoid resonance caused by the natural frequency of the chassis falling within the road excitation frequency range.The final optimization results showed that the first four orders of modal frequencies of the chassis were adjusted to 32.083 Hz,33.751 Hz,42.517 Hz,and 50.362 Hz,respectively,in the case that the chassis mass was increased by 6.714 kg(8.8%).They all avoid the range of road excitation frequency(10-30 Hz)so that the rice transplanter can effectively avoid the resonance phenomenon during operation.This study can provide a reference for the design and optimization of the chassis structure of transplanter.展开更多
Helicobacter pylori(H.pylori)infection remains a pivotal driver of chronic gastritis,peptic ulcer,gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer,yet its eradication is increasingly frustrated by...Helicobacter pylori(H.pylori)infection remains a pivotal driver of chronic gastritis,peptic ulcer,gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer,yet its eradication is increasingly frustrated by climbing antibiotic resistance and intolerable side-effects of standard triple or quadruple therapies.In recent years,fecal microbiota transplantation(FMT),a strategy that reconstructs the gut ecosystem by introducing a healthy donor microbiome,has emerged as a novel adjunct or alternative.By competitively excluding H.pylori,reinforcing mucosal barrier integrity,modulating host immunity and secreting bacteriocins,FMT can raise eradication rates,relieve dyspeptic symptoms and lower recurrence.This review synthesizes up-to-date pre-clinical,pilot and controlled clinical data,dissects underlying mechanisms,compares delivery routes,donor screening protocols and safety profiles,and discusses regulatory,ethical and standardization hurdles that must be overcome before large-scale clinical application.展开更多
Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival a...Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival and integration of neural stem cells into the host neural circuit remains a formidable challenge.Here,we investigated whether modifying the intrinsic properties of neural stem cells could enhance their integration post-transplantation.We focused on phosphatase and tensin homolog(PTEN),a well-characterized tumor suppressor known to critically regulate neuronal survival and axonal regeneration.By deleting Pten in mouse neural stem cells,we observed increased neurite outgrowth and enhanced resistance to neurotoxic environments in culture.Upon transplantation into injured spinal cords,Pten-deficient neural stem cells exhibited higher survival and more extensive rostrocaudal distribution.To examine the potential influence of partial PTEN suppression,rat neural stem cells were treated with short hairpin RNA targeting PTEN,and the PTEN knockdown resulted in significant improvements in neurite growth,survival,and neurosphere motility in vitro.Transplantation of sh PTEN-treated neural stem cells into the injured spinal cord also led to an increase in graft survival and migration to an extent similar to that of complete deletion.Moreover,PTEN suppression facilitated neurite elongation from NSC-derived neurons migrating from the lesion epicenter.These findings suggest that modifying intrinsic signaling pathways,such as PTEN,within neural stem cells could bolster their therapeutic efficacy,offering potential avenues for future regenerative strategies for spinal cord injury.展开更多
Traumatic optic neuropathy is a form of optic neuropathy resulting from trauma.Its pathophysiological mechanisms involve primary and secondary injury phases,leading to progressive retinal ganglion cell loss and axonal...Traumatic optic neuropathy is a form of optic neuropathy resulting from trauma.Its pathophysiological mechanisms involve primary and secondary injury phases,leading to progressive retinal ganglion cell loss and axonal degeneration.Contributing factors such as physical trauma,oxidative stress,neuroinflammation,and glial scar formation exacerbate disease progression and retinal ganglion cell death.Multiple forms of cell death—including apoptosis,pyroptosis,necroptosis,and ferroptosis—are involved at different disease stages.Although current treatments,such as corticosteroid therapy and surgical interventions,have limited efficacy,cell-based therapies have emerged as a promising approach that simultaneously promotes neuroprotection and retinal ganglion cell regeneration.This review summarizes recent advances in cell-based therapies for traumatic optic neuropathy.In the context of cell replacement therapy,retinal ganglion cell-like cells derived from embryonic stem cells and induced pluripotent stem cells—via chemical induction or direct reprogramming—have demonstrated the ability to integrate into the host retina and survive for weeks to months,potentially improving visual function.Mesenchymal stem cells derived from various sources,including bone marrow,umbilical cord,placenta,and adipose tissue,have been shown to enhance retinal ganglion cell survival,stimulate axonal regeneration,and support partial functional recovery.Additionally,neural stem/progenitor cells derived from human embryonic stem cells offer neuroprotective effects and function as“neuronal relays,”facilitating reconnection between damaged regions of the optic nerve and the visual pathway.Beyond direct cell transplantation,cell-derived products,such as extracellular vesicles and cell-extracted solutions,have demonstrated promising neuroprotective effects in traumatic optic neuropathy.Despite significant progress,several challenges remain,including limited integration of transplanted cells,suboptimal functional vision recovery,the need for precise timing and delivery methods,and an incomplete understanding of the role of the retinal microenvironment and glial cell activation in neuroprotection and neuroregeneration.Furthermore,studies with longer observation periods and deeper mechanistic insights into the therapeutic effects of cell-based therapies remain scarce.Two Phase I clinical trials have confirmed the safety and potential benefits of cell-based therapy for traumatic optic neuropathy,with reported improvements in visual acuity.However,further studies are needed to validate these findings and establish significant therapeutic outcomes.In conclusion,cell-based therapies hold great promise for treating traumatic optic neuropathy,but critical obstacles must be overcome to achieve functional optic nerve regeneration.Emerging bioengineering strategies,such as scaffold-based transplantation,may improve cell survival and axonal guidance.Successful clinical translation will require rigorous preclinical validation,standardized protocols,and the integration of advanced imaging techniques to optimize therapeutic efficacy.展开更多
With advances in solid organ transplantation,the option of combined kidney with other solid organ transplantation is an enticing option for patients with advanced kidney disease and concomitant other solid organ failu...With advances in solid organ transplantation,the option of combined kidney with other solid organ transplantation is an enticing option for patients with advanced kidney disease and concomitant other solid organ failure.Kidney allograft dysfunction is well known to be associated with increased adverse outcomes post solitary kidney transplant however,outcomes for patients and the kidney allograft are somewhat understudied in the setting of kidney transplantation when combined with other solid organ transplantation such as in a simultaneous liverkidney transplant.We will provide an overview of the current literature available on kidney allograft clinical outcome measures in combined solid organ transplant recipients such as delayed kidney allograft function,kidney allograft rejection,kidney allograft and patient survival metrics and how they compare to patients with kidney transplants alone.Worse kidney allograft survival outcomes were noted in most combined other organ with kidney transplantation(liver-kidney,heart-kidney,and lung-kidney)due to comorbidities attributed to non-renal organ dysfunction whereas improved kidney allograft survival outcomes were noted for pancreas-kidney transplantation.展开更多
Diabetes is a widespread disease affecting millions of people,making it one of the leading causes of death in the world.It is a leading cause of cardiovascular disease and end-stage renal disease.Despite advancements ...Diabetes is a widespread disease affecting millions of people,making it one of the leading causes of death in the world.It is a leading cause of cardiovascular disease and end-stage renal disease.Despite advancements in treatment,including insulin therapy and glucose monitoring devices,diabetes continues to significantly impact quality of life and current modalities do not reverse the end-organ damage associated with its progression.While traditionally indicated for type 1 diabetes,recent clinical practice refinements have made pancreas transplants available to select type 2 diabetics meeting specific criteria.These transplants are usually a part of a simultaneous kidney-pancreas transplant.However,although less frequently performed,transplants of pancreas alone or pancreas after kidney transplant are still available.For selected diabetic patients,pancreas transplants offer significant survival benefits and the improvement of cardiovascular and metabolic complications;however,they are not without risks.Complications such as bleeding,vascular thrombosis,infection,organ leak,and rejection are possible.Another challenge to pancreas transplantation is the decreasing number of procedures being performed due to decline in the volume of available highquality allografts and resource constraints of transplant centers.Advancements in monitoring and treatment of diabetes are contributing to the decline in pancreas transplants nowadays.展开更多
Background:The traditional method of heterotopic abdominal heart transplantation(HTx)involves crossclamping the inferior vena cava,which inevitably leads to bilateral lower limb ischemia(LI).This study first aimed to ...Background:The traditional method of heterotopic abdominal heart transplantation(HTx)involves crossclamping the inferior vena cava,which inevitably leads to bilateral lower limb ischemia(LI).This study first aimed to investigate the impact of LI on renal function in rats subjected to unilateral nephrectomy(UNx).Second,a modified method utilizing renal vessel-assisted anastomosis in rats with left UNx was compared with the traditional method for abdominal HTx.Methods:Male Sprague-Dawley rats were utilized as subjects for both experimental phases.In experiment 1,the animals were divided into four groups:sham operation group;LI group-rats undergoing occlusion of the abdominal aorta and vena cava below the renal vessels;UNx group-rats with left UNx;and LI+UNx group.All operated animals were monitored for up to 7 days for biochemical markers,renal histopathology,and survival rates.In experiment 2,we introduced the renal vessel-assisted method as the experimental group and compared it against the traditional method as the control within rat heterotopic HTx models.We assessed operative characteristics,echocardiography results,histological findings,and graft survival.Results:First,LI resulted in acute kidney dysfunction characterized by a decrease in 7day survival rates and creatinine clearance rates in both the LI and LI+UNx groups compared to the sham operation and UNx groups.Particularly,histopathological damage in the kidney and liver did not exhibit significant effects during this period.Second,the implementation of the renal vessel-assisted method significantly reduced bleeding volume at suture sites and enhanced the 7day survival rate compared to the traditional method.Conclusion:Acute kidney injury was induced by LI postoperation in treated rats.The renal vessel-assisted method demonstrated its effectiveness as a superior alternative that mitigates complications associated with the traditional method.展开更多
基金Brand Discipline Construction Project of Colleges and Universities in Jiangsu Province(PPZY2015A087)
文摘Shallow planting of the rice seedlings is an important factor for getting high yield as it can increase the effective tillers on the lownode of the stem. The 2 ZB-79 shallow rice seedling transplanter combined the advantages of shallow planting of the seedling-casting rice transplanter and orderly planting of the traditional rice transplanter. The principle of this kind of machine is firstly to cut the standardization nursery rice seedlings with rug soil into many small pieces,and then to plant the small pieces composed of pot soil and some seedlings on it to the field surface in order,only shallowly planted on the very top part of paddy soil. Not only it can keep the performance of planting shallowly and orderly,but also simplify many mechanisms for transition,separation,and plantation of rice seedlings. It is a new type of rice seedling transplanter called laying-type up to now to get higher efficiency when working and higher yield for rice production. This paper will introduce its developing results and analyze the comparative experiments.
基金the Henan provincial universities key research project plan basic research project(Grant No.23ZX011).
文摘To meet the operational criteria for mechanical transplanting of young seedlings in paddy-straw-made bowl-seedling trays,a new seedling needle and seedling pushing device have been developed.This paper presents the design process and analyzes the effects of key parameters,including the angle of inclination of flat edge,width of flat edge,length of flat edge,wedge angle,and width of seedling pushing device for new seedling needle and seedling pushing device.Optimization parameters of new seedling needle and seedling pushing device have been validated by orthogonal experiments.The optimized values,such as a flat edge inclination angle of 35°,a flat edge width of 10 mm,a flat edge length of 64 mm,a wedge angle of 60°,and a seedling-pushing device width of 8 mm,satisfy the operational requirements for mechanically transplanting young seedlings in paddy-straw-made bowl seedling trays.The results demonstrate significant improvements in transplanting efficiency within Chinese agricultural systems.
基金the National High Technology Research and Development Program of China(2012AA101903).
文摘In order to improve the automatic sorting and transplanting of tray-seedling and reduce labors strength,a new sorting transplanter was designed.According to the feature of normal seedling tray and manual grading method,the mechanical sorting procedure was defined.The key parts of sorting transplanter are as follows:an efficient transfer mechanism with aerodynamic buffer,a seedling identifying and measuring unit based on linear-structured vision,the extendible multi-grasper with wireless technology and the system controller.The experiments were conducted and showed that the transplanting success rate was 90.0% on the tray of 6×12 holes under the speed of 700 cycles per hour.The vision unit’s failed identifying rate for the superior pepper seedlings on five different trays was less than 10%,and the measurement error of seedling height was about 5 mm.
文摘An automatic feeding mechanism consisting of a timing shaft,an actuating device and a clutch for feeding paper pot seedlings from a horizontal slat type chain conveyor to a horizontal pusher type chain conveyor of a vegetable transplanter,was developed.The slat type chain conveyor carried the pot seedlings in upright orientation in the form of a rectangular array with each linear array of pot seedlings on a slat.The pusher type chain conveyor received a linear array of pot seedlings and delivered them to the seedling drop tube.Feeding of each linear array of pot seedlings to the pusher type conveyor at appropriate times was done using an automatic feeding mechanism.The laboratory evaluation indicated that the feeding rate of 33 to 50 pot seedlings per minute can be achieved with single set of conveyors.The feeding mechanism also worked effectively under actual field conditions with 98%to 99%of all the pot seedlings,which were properly separated and fed for planting when the forward speed of the vegetable transplanter was 0.9 km/h.The feeding mechanism has the general application of singulating rectangular array of items on the slat type chain conveyor in any industry and machine in motion on a level surface.
基金This research was financially supported by National Natural Science Foundation of China(No.31501230)Shandong Province Natural Science Foundation of China for Youths(No.ZR2014CQ058)+1 种基金the National Key Research and Development Program of China Sub-project(No.2017YFD0700405)Shandong Province Science and Technology Planning Project of Higher Education(No.J17KA145).
文摘Rice transplanting requires the operator to manipulate the rice transplanter in straight trajectories.Various markers are proposed to help experienced drivers in keeping straightforward and parallel to the previous path,which are extremely boring in terms of large-scale fields.The objective of this research was to develop an autonomous navigation system that automatically guided a rice transplanter working along predetermined paths in the field.The rice transplanter used in this research was commercially available and originally manually-operated.An automatic manipulating system was developed instead of manual functions including steering,stop,going forward and reverse.A sensor fusion algorithm was adopted to integrate measurements of the Real-Time Kinematic Global Navigation Satellite System(RTK-GNSS)and Inertial Measurement Unit(IMU),and calculate the absolute moving direction under the UTM coordinate system.A headland turning control method was proposed to ensure a robust turning process considering that the rice transplanter featured a small turning radius and a relatively large slip rate at extreme steering angles.Experiments were designed and conducted to verify the performance of the newly developed autonomous navigation system.Results showed that both lateral and heading errors were less than 8 cm and 3 degrees,respectively,in terms of following straight paths.And headland turns were robustly executed according to the required pattern.
基金This study was funded by Scientific and Technological Project(Grant Number:2014BAD06 B01-1)Universities Science and Technology Innovation Team(Project Number:2014TD010)in Heilongjiang Province and Heilongjiang Land Reclamation Bureau Project(HNK125B-06-02A).
文摘This research aimed to solve current problems in the process of maize transplanting in China such as large labor intensity,low working efficiency and poor quality.On the basis of the structure of a seedling-sprouting tray made of maize straw and the agronomic requirements of maize production,this study developed a new feeding device for such a sprouting tray,determined the dimensions of the key components in a virtual environment via Solid Edge software and obtained optimal working parameters in combination with Matlab.Some tests on field validation and maize production were conducted as well.The test results showed the importance of the working parameters on an upright degree in descending order(as well as the best working parameters)to be the vertical angle of seedling planting(13.14°),the forward speed of locomotion(0.57 m/s),and the horizontal angle of the seedling box(22.5°).The standard deviation of the field validation was 6.04%,which was within the allowable range to meet the requirements of maize transplanting.Compared with maize transplanting machines(and manual transplanting operations)on the current market,the labor inputs,as well as the rates of spacing and upright degree qualification,omitted planting and the yield using the new feeding device for automatic transplanter with maize straw seedling-sprouting trays increased 0(6.9%),0(3.1%),0(4.5%)and 0(−1.0%),respectively;whereas,the manufacturing cost was reduced by 35.5%.The results can provide a technical basis and reference for subsequent development of automatic transplanters with maize straw seedling-sprouting trays.
基金The authors thank the editors and the anonymous reviewers whose constructive comments have notably contributed to the improved quality and clarity of this paper.This article was supported in part by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ16E05003)the Natural Key Research and Development Program of China(Project No.2017YFD0700800)and the Science Foundation of Zhejiang Sci-Tech University(Grant No.15022011-Y).
文摘The rotary plug seedling pick-up mechanism for vegetable automatic transplanter is the technical bottleneck to improve the mechanization level of vegetable planting in China.In order to solve the problems of rotary seedling pick-up mechanism proposed in previous study,such as low success ratio of seedling pick-up at high speed,and interference between the seedling bowl and the end of the other seedling pick-up arm,a novel kind of rotary seedling pick-up mechanism of planetary gear train with combined type gears of incomplete denatured-eccentric-circular and non-circular gears was proposed.Through kinematic analysis of the seedling pick-up mechanism,the kinematics model was established.The computer-aided analysis and optimization software with human-computer interaction method was developed to realize parameters optimization of the seedling pick-up mechanism.Three-dimensional parametric design system of seedling pick-up mechanisms with combined non-circular gear transmission was developed for mechanism virtual simulation to verify the correctness of theoretical model and design results of the mechanism.The physical prototype of the mechanism was manufactured,and high-speed camera kinematics tests of the mechanism were conducted in the laboratory to study its kinematic characteristics.Laboratory seedling pick-up tests were carried out.The mechanism has the success ratio of seedling pick-up 96.3%without interference during seedling transporting when the rotation speed of the mechanism is 50 r/min and the seedling transplanting efficiency is 100 plants/min per row,showing that the novel mechanism has better working performance than the original one and could be applied in vegetable plug seedling transplanter.
基金This research was supported by the National Key Research and Development Project of China(2017YFD0301404-05)and the Fundamental Research Funds for the Central Universities(2662018PY038).
文摘To improve the precision of deep fertilization of paddy fields,a six-row centralized pneumatic deep precision fertilization device for a rice transplanter was designed.This device included a spiral fertilizer distribution system,centralized pneumatic fertilizer delivery system,an opener system,and a fertilization control system.The centralized airflow distribution method was used in the fertilizer delivery system to ensure that the airflow in each fertilizer pipe was evenly distributed.The rotational speeds of the power take-off(PTO)and fertilizer shaft were measured synchronously using photoelectric sensors and matched proportionately in real-time using PID closed-loop control algorithms to achieve precise fertilization rates at each working speed of the rice transplanter.There were two key considerations in the design of the control system to ensure precise fertilization.Firstly,a photoelectric sensor was used to measure the speed of the PTO;the high rotational speed of the PTO could provide a high signal frequency and improve the precision of the measurement of the transplanter’s working speed.Secondly,the fertilizer shaft speed measurement subprogram was set to sleep for a short period to reduce the vibration caused by the engine.During the tests of pneumatic fertilizer delivery system,single-factor tests on airflow distribution methods were conducted.The results showed that the coefficient of variation of the airflow speed for the centralized airflow distribution method was 1.67%,which was the least among the coefficients of the three distribution methods.In the bench tests,the rotational speeds of the fertilizer shaft were set at 10 r/min,20 r/min,30 r/min,and 40 r/min.The maximum coefficient of variation of the fertilization consistency in different rows was 1.49%at the rotational speed of 20 r/min.The maximum coefficient of variation of the fertilization stability was 2.86%at the rotational speed of 40 r/min,while the average fertilizer amount per lap for each distributor was 26.25 g/r.The results of the dynamic fertilization tests showed that the maximum relative error of the fertilizer distribution amount was 2.00%when the target fertilizer rates were 20,30,and 40 kg/667 m2.The results of the field tests showed that the average relative error of the fertilization amount was 3.53%,which satisfies the design standard.This research provides a reference for optimizing pneumatic fertilizer delivery systems and improving fertilization control systems and other pneumatic precision fertilizer application devices.
基金supported by the National Natural Science Foundation of China(51575284)the National Key Research and Development Program of China(2017YFD0700804)Funds for Modern Agricultural Industry Technology System Construction of China(CARS-13).
文摘Considering both high efficiency and high seedling standing quality is a significant objective for crop mechanized transplanting.Rape blanket seedling transplanting is an innovative and efficient transplanting technique.However,falling off phenomenon has become a common problem facing rape blanket seedling transplanting fields that causes seedling standing quality decrease and restricts crop growth.In this study,the rape blanket seedling of Ningza-1838 varieties and 35 d of seedling age was taken as the research object.The critical falling off equations of seedling was established by dynamic analysis.Main factors affecting seedling falling off were obtained.The critical value of each factor was calculated which were as follows:the rotation speed of the planting mechanism was 24.6 rad/s,the substrate moisture content was 50.4%and the longitudinal picking seedling quantity was 14.7 mm.Taking the seedling falling off rate as evaluation index,the measured critical value of seedling falling off was determined by high speed photography experiment.Under the condition that substrate moisture content was 55%and the longitudinal seedling quantity was 15 mm,the seedling falling off rate sharply increased when the transplanting mechanism rotation speed was increased from 24 rad/s to 26 rad/s.Under the condition that the rotation speed was 22 rad/s and the longitudinal picking seedling quantity was 15 mm,the seedling falling off rate rapidly decreased when the moisture content was increased from 47%to 53%.When moisture content exceeded 53%,this exhibited no obvious change.Under the condition that the moisture content was 50%and the rotation speed was 22 rad/s,the seedling falling off rate swiftly raised when the longitudinal picking seedling quantity was increased from 14 mm to 17 mm.The experimental results showed that the seedling falling off rate increased significantly near the critical value.The experimental results showed that the seedling falling off rate changed significantly near the critical value.It proved that the model was correct.Response surface experiments with the Box-Behnken design were conducted to determine the optimal combination parameters,which were as follows:substrate moisture content was 56.24%,planting mechanism rotation speed was 22.04 rad/s,and longitudinal picking seedling quantity was 14.91 mm.At this time,the seedling falling off rate was 1.36%,which ensured that seedlings could be transplanted stably under the carrier of seedling needle.The verification test was conducted,and the working parameters were adjusted according to the optimization results in experiment.The results of verification test were highly consistent with the optimization solution.The present study may provide a theoretical method for improving seedling standing quality of rape blanket seedling,and laid a foundation for the popularization and development of rape carpet seedling transplanting.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51875175)the Natural Science Foundation of Henan Province(Grant No.202300410124)+1 种基金Scientific and technological project in Henan Province(Grant No.212102110223)Special projects for industrial foundation reconstruction and high-quality development of manufacturing industry in MIIT.
文摘The chassis of rice transplanter tends to vibrate severely in the severe working environment,causing a severe effect on the operational performance and driving comfort.In order to avoid this situation,this paper constructs a vibration evaluation system of the rice transplanter and carries out experimental analysis.According to the optimal acceleration sensor placement scheme,a test platform system was designed.Taking the high-speed transplanter chassis as the research object,this study carried out the experiments modal analysis and optimization on the chassis.The three-dimensional model of the transplanting machine chassis established by SolidWorks was imported into ANSYS Workbench for finite element modal simulation analysis.Comparing the two modal analyses,it is found that the results data of the two analysis methods were very close.After optimization,the length x1,the section width x2 and the thickness of the hollow beam x3 of the main load-bearing beam of the frame were as follows:x1=1641.5 mm,x2=26.7 mm,x3=5 mm,respectively.The maximum overshoot of the low-level system was reduced by 28.57%.It has been verified that the vibration of the whole machine has been effectively reduced.
基金supported by the National Key Research Program of China(2017YFD0700800)the National Natural Science Foundation of China(50905153,51565059)+1 种基金Autonomous Region Key Research Projects(2018B01001-3)Autonomous Region Tianshan Youth Program(2017Q018).
文摘To improve the low transplanting efficiencies and simplify the complex structures of current automatic transplanters,a mechanical high-speed transplanter for picking plug seedlings that is suitable for planting on plastic filmswas designed.Themain components were an automatic seedling picking systemand a basket-type planting system,whichwere used for the following processes:automatic picking,planting,soil covering,and suppression of plug seedlings.The performance test was performed on the automatic transplanter with 60-day-old pepper seedlings.The transplanting efficiency was tested at speeds of 40,60,90,and 120 plants·min−1.The results showed that the coefficient of variation(CV)of the plant spacing and the missed transplanting rate increased with the planting frequency,whereas the qualified rate of planting perpendicularity and the qualified rate of planting decreasedwith the increase in the planting frequency.All planting indicesmet the JB/T 102912013 standards.The results of this study showed that the auto-transplanter could performhigh-speed transplanting on the basis of completing the following functions:automatic picking,planting,soil covering,and suppression of plug seedlings.
基金This work was supported by the Industrial Strategic Technology Development Program(10062546,Construction database of work load and development of simulation model for tractor powertrain)funded by the Ministry of Trade,Industry&Energy(MI,Korea).
文摘The aim of this study was to analyze the effects of the planting distance and depth on the power take-off(PTO)load spectrum of a small riding-type transplanter for the optimal design of the transplanter.To measure load data during actual planting operation,a load measurement system was developed using a torque sensor,a data acquisition system,and an inverter.Field experiments were conducted at four planting distances(26 cm,35 cm,43 cm,and 80 cm)and three planting depths(85 mm,105 mm,and 136 mm)in a field with similar soil conditions.The measured load data were inverted into a load spectrum using rain-flow counting and Smith-Watson-Topper(SWT)methods.The safety factor of a transplanter according to the planting conditions was analyzed using the converted load spectrum and commercial software.The load spectrum for all planting conditions showed torque ratios similar within a high cycle region of 108 to 109.The torque ratio increased when the planting depth increased and planting distance decreased in the low cycle region under less than 108 cycles.The safety factors of the PTO driving gear and the driven gear increased as the planting distance increased at all planting depths.When the planting depth decreased at the same planting distance,the safety factor of the PTO gears increased.The results of this study might provide useful information for a transplanter PTO design considering the working load according to the various planting conditions.
基金We acknowledge the financial support by the German Research Foundation and the Open Access Publication Fund of the Technische Universitaet Berlin.
文摘This paper presents the study reports on evaluating a new transplanting operation by taking into accounts the interactions between soil,plant,and machine in line with the System of Rice Intensification(SRI)practices.The objective was to modify planting claw(kuku-kambing)of a paddy transplanter in compliance with SRI guidelines to determine the best planting spacing(S),seed rate(G)and planting pattern that results in a maximum number of seedling,tillers per hill,and yield.Two separate experiments were carried out in two different paddy fields,one to determine the best planting spacing(S=4 levels:s_(1)=0.16 m×0.3 m,s_(2)=0.18 m×0.3 m,s_(3)=0.21 m×0.3 m,and s_(4)=0.24 m×0.3 m)for a specific planting pattern(row mat or scattered planting pattern),and the other to determine the best combination of spacing with seed rate treatments(G=2 levels:g1=75 g/tray,and g2=240 g/tray).Main SRI management practices such as soil characteristics of the sites,planting depth,missing hill,hill population,the number of seedling per hill,and yield components were evaluated.Results of two-way analysis of variance with three replications showed that spacing,planting pattern and seed rate affected the number of one-seedling in all experiment.It was also observed that the increase in spacing resulted in more tillers and more panicle per plant,however hill population and sterility ratio increased with the decrease in spacing.While the maximum number of panicles were resulted from scattered planting at s_(4)=0.24 m×0.3 m spacing with the seed rate of g1=75 g/tray,the maximum number of one seedling were observed at s_(4)=0.16 m×0.3 m.The highest and lowest yields were obtained from 75 g seeds per tray scattered and 70 g seeds per tray scattered treatment respectively.For all treatments,the result clearly indicates an increase in yield with an increase in spacing.
基金financially supported by the National Key Research and Development Program of China Subproject(Grant No.2021YFD2000601)Innovation Scientists and Technicians Talent Projects of Henan Provincial Department of Education(Grant No.23IRTSTHN015,No.202300410124)。
文摘The vibration problem during the operation of rice transplanters is the most common phenomenon.In order that the static and dynamic characteristics of the rice transplanter chassis can meet the requirements of more stable operation,the research took the 2ZG-6DK rice transplanter as the research object to carry out a vibration reduction optimization study.In the research,the Pro/Engineer 5.0 software was first used to model the chassis of the rice transplanter.The constructed finite element model was revised by using the structural parameter revision method and the mixed penalty function method.The model was imported into ANSYS Workbench to solve the modal frequency and vibration shape of the rice transplanter chassis.Based on the MAC(modal assurance criterion)criterion,modal tests were carried out to verify the accuracy of the finite element theoretical analysis.Through the analysis of the characteristics of the external excitation frequency,the chassis is structurally optimized to avoid resonance caused by the natural frequency of the chassis falling within the road excitation frequency range.The final optimization results showed that the first four orders of modal frequencies of the chassis were adjusted to 32.083 Hz,33.751 Hz,42.517 Hz,and 50.362 Hz,respectively,in the case that the chassis mass was increased by 6.714 kg(8.8%).They all avoid the range of road excitation frequency(10-30 Hz)so that the rice transplanter can effectively avoid the resonance phenomenon during operation.This study can provide a reference for the design and optimization of the chassis structure of transplanter.
基金the 2026 Health Commission Fund of Guizhou Province,China.the freestatistics suite for its technical support.
文摘Helicobacter pylori(H.pylori)infection remains a pivotal driver of chronic gastritis,peptic ulcer,gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer,yet its eradication is increasingly frustrated by climbing antibiotic resistance and intolerable side-effects of standard triple or quadruple therapies.In recent years,fecal microbiota transplantation(FMT),a strategy that reconstructs the gut ecosystem by introducing a healthy donor microbiome,has emerged as a novel adjunct or alternative.By competitively excluding H.pylori,reinforcing mucosal barrier integrity,modulating host immunity and secreting bacteriocins,FMT can raise eradication rates,relieve dyspeptic symptoms and lower recurrence.This review synthesizes up-to-date pre-clinical,pilot and controlled clinical data,dissects underlying mechanisms,compares delivery routes,donor screening protocols and safety profiles,and discusses regulatory,ethical and standardization hurdles that must be overcome before large-scale clinical application.
基金supported by the National Research Foundation of Korea,Nos.2021R1A2C2006110,2021M3E5D9021364,2019R1A5A2026045(to BGK)the Korea Initiative for Fostering University of Research and Innovation(KIURI)Program of the NRF funded by the MSIT(to HK),No.NRF2021M3H1A104892211(to HSK)。
文摘Spinal cord injury results in permanent loss of neurological functions due to severance of neural networks.Transplantation of neural stem cells holds promise to repair disrupted connections.Yet,ensuring the survival and integration of neural stem cells into the host neural circuit remains a formidable challenge.Here,we investigated whether modifying the intrinsic properties of neural stem cells could enhance their integration post-transplantation.We focused on phosphatase and tensin homolog(PTEN),a well-characterized tumor suppressor known to critically regulate neuronal survival and axonal regeneration.By deleting Pten in mouse neural stem cells,we observed increased neurite outgrowth and enhanced resistance to neurotoxic environments in culture.Upon transplantation into injured spinal cords,Pten-deficient neural stem cells exhibited higher survival and more extensive rostrocaudal distribution.To examine the potential influence of partial PTEN suppression,rat neural stem cells were treated with short hairpin RNA targeting PTEN,and the PTEN knockdown resulted in significant improvements in neurite growth,survival,and neurosphere motility in vitro.Transplantation of sh PTEN-treated neural stem cells into the injured spinal cord also led to an increase in graft survival and migration to an extent similar to that of complete deletion.Moreover,PTEN suppression facilitated neurite elongation from NSC-derived neurons migrating from the lesion epicenter.These findings suggest that modifying intrinsic signaling pathways,such as PTEN,within neural stem cells could bolster their therapeutic efficacy,offering potential avenues for future regenerative strategies for spinal cord injury.
基金supported by the National Key Research and Development Program of China,No.2022YFA1105502(to PG)the National Natural Science Foundation of China,Nos.82271123(to PG),32200618(to ZT)。
文摘Traumatic optic neuropathy is a form of optic neuropathy resulting from trauma.Its pathophysiological mechanisms involve primary and secondary injury phases,leading to progressive retinal ganglion cell loss and axonal degeneration.Contributing factors such as physical trauma,oxidative stress,neuroinflammation,and glial scar formation exacerbate disease progression and retinal ganglion cell death.Multiple forms of cell death—including apoptosis,pyroptosis,necroptosis,and ferroptosis—are involved at different disease stages.Although current treatments,such as corticosteroid therapy and surgical interventions,have limited efficacy,cell-based therapies have emerged as a promising approach that simultaneously promotes neuroprotection and retinal ganglion cell regeneration.This review summarizes recent advances in cell-based therapies for traumatic optic neuropathy.In the context of cell replacement therapy,retinal ganglion cell-like cells derived from embryonic stem cells and induced pluripotent stem cells—via chemical induction or direct reprogramming—have demonstrated the ability to integrate into the host retina and survive for weeks to months,potentially improving visual function.Mesenchymal stem cells derived from various sources,including bone marrow,umbilical cord,placenta,and adipose tissue,have been shown to enhance retinal ganglion cell survival,stimulate axonal regeneration,and support partial functional recovery.Additionally,neural stem/progenitor cells derived from human embryonic stem cells offer neuroprotective effects and function as“neuronal relays,”facilitating reconnection between damaged regions of the optic nerve and the visual pathway.Beyond direct cell transplantation,cell-derived products,such as extracellular vesicles and cell-extracted solutions,have demonstrated promising neuroprotective effects in traumatic optic neuropathy.Despite significant progress,several challenges remain,including limited integration of transplanted cells,suboptimal functional vision recovery,the need for precise timing and delivery methods,and an incomplete understanding of the role of the retinal microenvironment and glial cell activation in neuroprotection and neuroregeneration.Furthermore,studies with longer observation periods and deeper mechanistic insights into the therapeutic effects of cell-based therapies remain scarce.Two Phase I clinical trials have confirmed the safety and potential benefits of cell-based therapy for traumatic optic neuropathy,with reported improvements in visual acuity.However,further studies are needed to validate these findings and establish significant therapeutic outcomes.In conclusion,cell-based therapies hold great promise for treating traumatic optic neuropathy,but critical obstacles must be overcome to achieve functional optic nerve regeneration.Emerging bioengineering strategies,such as scaffold-based transplantation,may improve cell survival and axonal guidance.Successful clinical translation will require rigorous preclinical validation,standardized protocols,and the integration of advanced imaging techniques to optimize therapeutic efficacy.
文摘With advances in solid organ transplantation,the option of combined kidney with other solid organ transplantation is an enticing option for patients with advanced kidney disease and concomitant other solid organ failure.Kidney allograft dysfunction is well known to be associated with increased adverse outcomes post solitary kidney transplant however,outcomes for patients and the kidney allograft are somewhat understudied in the setting of kidney transplantation when combined with other solid organ transplantation such as in a simultaneous liverkidney transplant.We will provide an overview of the current literature available on kidney allograft clinical outcome measures in combined solid organ transplant recipients such as delayed kidney allograft function,kidney allograft rejection,kidney allograft and patient survival metrics and how they compare to patients with kidney transplants alone.Worse kidney allograft survival outcomes were noted in most combined other organ with kidney transplantation(liver-kidney,heart-kidney,and lung-kidney)due to comorbidities attributed to non-renal organ dysfunction whereas improved kidney allograft survival outcomes were noted for pancreas-kidney transplantation.
文摘Diabetes is a widespread disease affecting millions of people,making it one of the leading causes of death in the world.It is a leading cause of cardiovascular disease and end-stage renal disease.Despite advancements in treatment,including insulin therapy and glucose monitoring devices,diabetes continues to significantly impact quality of life and current modalities do not reverse the end-organ damage associated with its progression.While traditionally indicated for type 1 diabetes,recent clinical practice refinements have made pancreas transplants available to select type 2 diabetics meeting specific criteria.These transplants are usually a part of a simultaneous kidney-pancreas transplant.However,although less frequently performed,transplants of pancreas alone or pancreas after kidney transplant are still available.For selected diabetic patients,pancreas transplants offer significant survival benefits and the improvement of cardiovascular and metabolic complications;however,they are not without risks.Complications such as bleeding,vascular thrombosis,infection,organ leak,and rejection are possible.Another challenge to pancreas transplantation is the decreasing number of procedures being performed due to decline in the volume of available highquality allografts and resource constraints of transplant centers.Advancements in monitoring and treatment of diabetes are contributing to the decline in pancreas transplants nowadays.
基金The Youth Project of Tianjin Natural Science Foundation,Grant/Award Number:23JCQNJC01380。
文摘Background:The traditional method of heterotopic abdominal heart transplantation(HTx)involves crossclamping the inferior vena cava,which inevitably leads to bilateral lower limb ischemia(LI).This study first aimed to investigate the impact of LI on renal function in rats subjected to unilateral nephrectomy(UNx).Second,a modified method utilizing renal vessel-assisted anastomosis in rats with left UNx was compared with the traditional method for abdominal HTx.Methods:Male Sprague-Dawley rats were utilized as subjects for both experimental phases.In experiment 1,the animals were divided into four groups:sham operation group;LI group-rats undergoing occlusion of the abdominal aorta and vena cava below the renal vessels;UNx group-rats with left UNx;and LI+UNx group.All operated animals were monitored for up to 7 days for biochemical markers,renal histopathology,and survival rates.In experiment 2,we introduced the renal vessel-assisted method as the experimental group and compared it against the traditional method as the control within rat heterotopic HTx models.We assessed operative characteristics,echocardiography results,histological findings,and graft survival.Results:First,LI resulted in acute kidney dysfunction characterized by a decrease in 7day survival rates and creatinine clearance rates in both the LI and LI+UNx groups compared to the sham operation and UNx groups.Particularly,histopathological damage in the kidney and liver did not exhibit significant effects during this period.Second,the implementation of the renal vessel-assisted method significantly reduced bleeding volume at suture sites and enhanced the 7day survival rate compared to the traditional method.Conclusion:Acute kidney injury was induced by LI postoperation in treated rats.The renal vessel-assisted method demonstrated its effectiveness as a superior alternative that mitigates complications associated with the traditional method.
