In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strate...In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strategy is discussed by Mazur’s theorem and optimality condition is derived by means of normal cone.展开更多
Chicken body weight(BW)is a critical trait in breeding.Although genetic variants associated with BW have been investigated by genome-wide association studies(GWAS),the contributions of causal variants and their molecu...Chicken body weight(BW)is a critical trait in breeding.Although genetic variants associated with BW have been investigated by genome-wide association studies(GWAS),the contributions of causal variants and their molecular mechanisms remain largely unclear in chickens.In this study,we construct a comprehensive genetic atlas of chicken BW by integrative analysis of 30 age points and 5 quantitative trait loci(QTL)across 27 tissues.We find that chicken growth is a cumulative non-linear process,which can be divided into three distinct stages.Our GWAS analysis reveals that BW-related genetic variations show ordered patterns in these three stages.Genetic variations in chromosome 1 may regulate the overall growth process,likely by modulating the hypothalamus-specific expression of SLC25A30 and retina-specific expression of NEK3.Moreover,genetic variations in chromosome 4 and chromosome 27 may play dominant roles in regulating BW during Stage 2(8-22 weeks)and Stage 3(23-72 weeks),respectively.In summary,our study presents a comprehensive genetic atlas regulating developmental stage-specific changes in chicken BW,thus providing important resources for genomic selection in breeding programs.展开更多
This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem....This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem. By Mazur＇s theorem, the existence of optimal control strategy is demonstrated and optimality conditions derived by means of normal cone.展开更多
To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these me...To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.展开更多
The O subfamily of forkhead box(FoxO) proteins is the downstream effector of the insulin-like growth factor-1/phosphoinositide 3-kinase/protein kinase B(IGF-1/PI3K/PKB) signal pathway.The objective of the present stud...The O subfamily of forkhead box(FoxO) proteins is the downstream effector of the insulin-like growth factor-1/phosphoinositide 3-kinase/protein kinase B(IGF-1/PI3K/PKB) signal pathway.The objective of the present study was to examine the expressions of three members of FoxO proteins,FoxO1,FoxO3a,and FoxO4 in the duodenum of Sprague-Dawley rats at different ages.The result demonstrated that the expression of FoxO4 in rat duodenum showed an age-dependent manner.At Day 21,there were no detectable localization and expression of FoxO4 in the duodenum,while,at Months 2 and 6,localization and expression of FoxO4 were distinct.In addition,FoxO4 staining was primarily concentrated in the cell nuclei of the lamina propria around the intestinal gland of the duodenum in 2-month-old rats,but was not detectable in the same area in 6-month-old rats.Our results showed also that although FoxO3a existed in the cytoplasm of the lamina propria at a low level at the 2-and 6-month marks,it was still not detectable at Day 21.Besides,FoxO1 was not detectable in all parts and stages.Taken together,our findings suggested that the cell-specific and age-dependent expressional patterns of FoxO4 and FoxO3a proteins in the duodenum play some roles in the development and growth performance of the rat duodenum.展开更多
A SEI model for hepatitis B is constructed where the susceptibility and other crucial transmission probabilities depend on the chronological age and the basic reproduction rate R0 is derived. Under suitable (biologica...A SEI model for hepatitis B is constructed where the susceptibility and other crucial transmission probabilities depend on the chronological age and the basic reproduction rate R0 is derived. Under suitable (biological and mathematical) assumptions in a closed population, results of Houpa D. D. E. et al. [1] are extended from constant case of p and q to age-dependent case: the disease-free equilibrium is globally asymptotically stable (GAS) if R0 . On the other hand, R0 > 1 induces that endemic equilibrium is GAS and the system is uniformly persistent.展开更多
Objective To verify whether peripheral blood circulation and arterial wall distensibility are influenced by atmospheric pressure （AtPr） and to examine if their association is dependent on age and/or sex. Methods Ass...Objective To verify whether peripheral blood circulation and arterial wall distensibility are influenced by atmospheric pressure （AtPr） and to examine if their association is dependent on age and/or sex. Methods Associations among natural AtPr levels （on the examination day as well as 1 and 2 days prior）, limb muscle hemodynamics, and distensibility of conduit arteries were retrospectively examined in an observational study of 276 untreated patients with primary moderate hypertension （mean age 56.4 years, 194 men）. Forearm and calf circulations at rest and 3 min after ischemia were measured by venous occlusion plethysmography. Compliance of the brachial and shank arteries was assessed by oscillometry. Results After adjustment for age, degree of hypertension, and season, correlation and multiple resression analyses revealed a season-independent but age-dependent direct correlation between the stiffness of limb arteries and AtPr levels on the examination day in men, but not women. The association weakened with the degree of hypertension, disappeared with age, and was more evident in the arms than in the legs. Conclusion Parameters of arterial wall distensibility in adult hypertensive men are susceptible to AtPr changes within the usually observed limits （730-770 mmHg）. It is proposed that reduction of arterial wall barometric responsiveness in women and aging men is a likely mechanism underlying their meteosensitivity.展开更多
In this and upcoming papers,the authors investigate optimal policies for two age-dependent populations with the interaction of predator and prey,which is described by an integro-differential system and controlled by f...In this and upcoming papers,the authors investigate optimal policies for two age-dependent populations with the interaction of predator and prey,which is described by an integro-differential system and controlled by fertility.As the starting point of research,this article is mainly devoted to the well-posedness of basic model by means of contraction mapping principle.展开更多
Crohn’s disease is a chronic inflammatory disease process involving different sites in the gastrointestinal tract. Occasionally, so-called metastatic disease occurs in extra-intestinal sites. Granulomatous...Crohn’s disease is a chronic inflammatory disease process involving different sites in the gastrointestinal tract. Occasionally, so-called metastatic disease occurs in extra-intestinal sites. Granulomatous inflammation may be detected in endoscopic biopsies or resected tissues. Genetic, epigenetic and environmental factors appear to play a role. Multiple susceptibility genes have been described in both familial and non-familial forms while the disease is phenotypically heterogeneous with a female predominance. The disorder occurs over a broad age spectrum, from early childhood to late adulthood. More than 80% are diagnosed before age 40 years usually with terminal ileal and colonic involvement. Pediatric-onset disease is more severe and more extensive, usually with a higher chance of upper gastrointestinal tract disease, compared to adult-onset disease. Long-term studies have shown that the disorder may evolve with time into more complex disease with stricture formation and penetrating disease complications (i.e., fistula, abscess). Although prolonged remission may occur, discrete periods of symptomatic disease may re-appear over many decades suggesting recurrence or re-activation of this inflammatory process. Eventual development of a cure will likely depend on identification of an etiologic cause and a fundamental understanding of its pathogenesis. Until now, treatment has focused on removing risk factors, particularly cigarette smoking, and improving symptoms. In clinical trials, clinical remission is largely defined as improved numerical and endoscopic indices for “mucosal healing”. “Deep remission” is a conceptual, more “extended” goal that may or may not alter the long-term natural history of the disease in selected patients, albeit at a significant risk for treatment complications, including serious and unusual opportunistic infections.展开更多
Crohn’s disease is a chronic inflammatory granulomatous process that usually involves different sites in the intestinal tract. Genetic and environmental factors are thought to play a role in its etiology and pathogen...Crohn’s disease is a chronic inflammatory granulomatous process that usually involves different sites in the intestinal tract. Genetic and environmental factors are thought to play a role in its etiology and pathogenesis. The disorder has a heterogeneous clinical expression and data from tertiary care settings have documented its female predominance, occasional familial nature, and high rate of stricture formation and penetrating disease. It may appear from early childhood to late adulthood, although over 80% are currently diagnosed before age 40 years, usually with terminal ileal and colonic involvement. Several studies have now shown differences in phenotypic clinical expression depending on the initial age at diagnosis, with pediatric-onset disease being more severe and more extensive with more involvement of the upper gastrointestinal tract compared to adult-onset disease. In addition, long- term studies from these tertiary care settings have documented that the disorder may evolve with time into a more complex disease with stricture formation and penetrating disease complications (i.e. fistula and abscess). Although prolonged remission with no evidence of inflammatory disease may occur, discrete periods of symptomatic and active granulomatous inflammatory disease may re-appear over many decades. Long-term studies on the natural history have also suggested that discrete events (or agents) may precipitate this granulomatous inflammatory process.展开更多
The negative-geotaxis climbing assay is used to efficiently study aging and neurodegeneration in Drosophila.To make it suitable for large-scale study,a method called the rapid iterative negative geotaxis（RING） assay...The negative-geotaxis climbing assay is used to efficiently study aging and neurodegeneration in Drosophila.To make it suitable for large-scale study,a method called the rapid iterative negative geotaxis（RING） assay has been established by simultaneously photographing the climbing of multiple groups of flies when they are manually tapped down in test tubes.Here,we automated the assay by using a well-controlled electric motor to drive the tapping,and a homemade program to analyze the climbing height of flies.Using the automated RING（aRING） assay,we found that the climbing ability of a strain of wild-type flies,males in particular,declined rapidly before day 21 after eclosion,but slowly from day 21 to 35.We also found that the expression of arctic mutant Aβ_（42） accelerated the age-dependent decline in the climbing ability of flies.Moreover,using aRING,we examined the effect of third chromosome deficiencies on the accelerated locomotor decline in Aβ_（42）-expressing flies,and isolated 7 suppressors and15 enhancers.展开更多
The German waltzing guinea pig is a strain of animals expressing deafness and severe balance disorders at birth.The mutation arose spontaneously in a breeding facility in Germany and as the affected animals show a cha...The German waltzing guinea pig is a strain of animals expressing deafness and severe balance disorders at birth.The mutation arose spontaneously in a breeding facility in Germany and as the affected animals show a characteristic waltzing behavior,the strain is named the German waltzing guinea pig.The strain is presently bred only at Karolinska Institutet.The hereditary inner ear impairment has a recessive mode of inheritance and the strain thus produces not only affected homozygotes but also symptom-free heterozygotes and fully normal offspring.The outcome depends solely on the genotype of the parents.The heterozygotes,which have obtained the 'waltzing' gene from one parent only,have normal hearing and no balance dysfunction.The heterozygous animals appear normal but will,in turn,carry the genetic defect to the next generation.The present thesis is focused on these animals.Noise and ototoxic drugs are well known stress factors that interfere negatively with the hearing organ in both humans and animals,causing hearing impairment.However,the inter-individual variability in susceptibility to auditory stress factors is surprisingly large,most likely due to different genetic predisposition.In this study,heterozygous animals of the German waltzing guinea pig,animals carrying a genetic defect known to cause severe hearing impairment,were used to study how an unexplored gene for deafness interacts with auditory stress agents,i.e.noise exposure and the ototoxic drugs gentamicin and cisplatin.Animals were exposed to both narrowband as well as broadband noise at different ages and hearing thresholds were measured using ABRs.Heterozygotes of the German waltzing guinea pig showed less threshold shifts compared to control strains.Older animals were less affected by the noise trauma than younger animals.To test the hypothesis that the efferent system contributes to protection of the inner ear against noise trauma,measurements using a new method of post onset adaptation of DPOAEs and maximum adaptation magnitude were conducted.The post onset adaptation of DPOAEs detected a strain difference at the higher frequency region while in the maximum adaptation magnitude method showed no difference between the strains.The heterozygous German waltzing guinea pigs displayed a distinctly increased resistance to noise exposures,manifested as reduced threshold shifts and faster recovery following acoustic overstimulation.However,when exposed to ototoxic drugs,the heterozygous carriers suffered from a more pronounced hearing loss.It is concluded that endogenous resistance to noise in the heterozygotes does not offer any protection against ototoxic drugs.The detailed mechanisms remain to be explored.展开更多
In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic...In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional calculus.We establish the existence of a unique solution of the given model with the given initial conditions.At last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.展开更多
In this paper, we investigate optimal policies for an age-dependent n-dimensional competition system, which is controlled by fertility. By using Dubovitskii-Milyutin＇s general theory, the maximum principles are obtai...In this paper, we investigate optimal policies for an age-dependent n-dimensional competition system, which is controlled by fertility. By using Dubovitskii-Milyutin＇s general theory, the maximum principles are obtained for the problems with free terminal states, infinite horizon, and target sets, respectively.展开更多
This paper is concerned with an optimal harvesting problem over an infinite horizon for age-dependent n-dimensional food chain model and the analysis of long-term behaviors of the optimal-controlled system. The existe...This paper is concerned with an optimal harvesting problem over an infinite horizon for age-dependent n-dimensional food chain model and the analysis of long-term behaviors of the optimal-controlled system. The existence of overtaking optimal policy is proved and a maximum principle is carefully derived by means of Dubovitskii-Milyutin functional analytical extremum theory. Weak and strong turnpike properties of optimal trajectories are established.展开更多
We consider an age-dependent branching process in random environments. The environments are represented by a stationary and ergodic sequence ξ = (ξ 0, ξ 1,…) of random variables. Given an environment ξ, the proce...We consider an age-dependent branching process in random environments. The environments are represented by a stationary and ergodic sequence ξ = (ξ 0, ξ 1,…) of random variables. Given an environment ξ, the process is a non-homogenous Galton-Watson process, whose particles in n-th generation have a life length distribution G(ξ n ) on ?+, and reproduce independently new particles according to a probability law p(ξ n ) on ?. Let Z(t) be the number of particles alive at time t. We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation, and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process. We then get expressions of the conditional mean E ξ Z(t) and the global mean EZ(t), and show their exponential growth rates by studying a renewal equation in random environments.展开更多
In this paper, we present the compensated stochastic θ method for stochastic age-dependent delay population systems（SADDPSs） with Poisson jumps. The definition of mean-square stability of the numerical solution is ...In this paper, we present the compensated stochastic θ method for stochastic age-dependent delay population systems（SADDPSs） with Poisson jumps. The definition of mean-square stability of the numerical solution is given and a sufficient condition for mean-square stability of the numerical solution is derived. It is shown that the compensated stochastic θ method inherits stability property of the numerical solutions. Finally,the theoretical results are also confirmed by a numerical experiment.展开更多
The cohort study by Li et al provides timely and clinically relevant evidence on the use of recombinant human thrombopoietin(rhTPO)in pediatric allogeneic hematopoietic stem cell transplantation.The authors report enh...The cohort study by Li et al provides timely and clinically relevant evidence on the use of recombinant human thrombopoietin(rhTPO)in pediatric allogeneic hematopoietic stem cell transplantation.The authors report enhanced platelet engraftment and a favorable safety profile,particularly in younger children aged 0-9 years.This age-dependent difference not only highlights the physiological responsiveness of early hematopoietic environments to rhTPO but also raises important questions about tailoring supportive therapies across pediatric age groups.While the findings are promising,the lack of a control group and single-center limitations warrant further multicenter,long-term investigations.Ne-vertheless,the study lays a compelling foundation for integrating rhTPO more broadly into pediatric transplant protocols and for advancing individualized post-transplant care.展开更多
This paper is concerned with optimal harvesting control of a first order partial differential equation system representing a nonlinear n-dimensional competitive population model with age-structure. By the Ekeland＇s v...This paper is concerned with optimal harvesting control of a first order partial differential equation system representing a nonlinear n-dimensional competitive population model with age-structure. By the Ekeland＇s variational principle, the existence and unique char- acterization of the optimal control strategy are established. The optimality conditions for the control problem are obtained by the concept of the normal cone.展开更多
In recent years, population growth models with spatial diffusion have beenextensively studied by many authors (for example, see [1-5]). In this paper, a populationgrowth model is considered with a discrete age-depende...In recent years, population growth models with spatial diffusion have beenextensively studied by many authors (for example, see [1-5]). In this paper, a populationgrowth model is considered with a discrete age-dependence and spatial diffusion, and isinvestigated in a semigroup framework. The spectral properties of the population oper-ator are given. On the basis of such spectral consideration, the asymptotic behaviourof the semigroup generated by the population operator is obtained. Finally, a nonlinearpopulation growth model is considered and its stability is analyzed.展开更多
基金supported by the National Natural Science Foundation of China(11061017)the Natural Science Foundation of Gansu Province(1010RJZA075)
文摘In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strategy is discussed by Mazur’s theorem and optimality condition is derived by means of normal cone.
基金supported by the National Key Research and Development Program of China(2022YFF1000204 and 2021YFD1300600)STI 2030-Major Projects(2023ZD04052)+2 种基金the Open Projects of Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province(JQLAB-KF-202301)China Agriculture Research Systems(CARS-40)the 2115 Talent Development Program of China Agricultural University。
文摘Chicken body weight(BW)is a critical trait in breeding.Although genetic variants associated with BW have been investigated by genome-wide association studies(GWAS),the contributions of causal variants and their molecular mechanisms remain largely unclear in chickens.In this study,we construct a comprehensive genetic atlas of chicken BW by integrative analysis of 30 age points and 5 quantitative trait loci(QTL)across 27 tissues.We find that chicken growth is a cumulative non-linear process,which can be divided into three distinct stages.Our GWAS analysis reveals that BW-related genetic variations show ordered patterns in these three stages.Genetic variations in chromosome 1 may regulate the overall growth process,likely by modulating the hypothalamus-specific expression of SLC25A30 and retina-specific expression of NEK3.Moreover,genetic variations in chromosome 4 and chromosome 27 may play dominant roles in regulating BW during Stage 2(8-22 weeks)and Stage 3(23-72 weeks),respectively.In summary,our study presents a comprehensive genetic atlas regulating developmental stage-specific changes in chicken BW,thus providing important resources for genomic selection in breeding programs.
基金the National Natural Science Foundation of China(No.10771048)‘Qing Lan’Talent Engineering Funds of Lanzhou Jiaotong University(No.QL-05-18A)
文摘This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem. By Mazur＇s theorem, the existence of optimal control strategy is demonstrated and optimality conditions derived by means of normal cone.
基金supported by University of Macao,China,Nos.MYRG2022-00054-FHS and MYRG-GRG2023-00038-FHS-UMDF(to ZY)the Macao Science and Technology Development Fund,China,Nos.FDCT0048/2021/AGJ and FDCT0020/2019/AMJ and FDCT 0011/2018/A1(to ZY)Natural Science Foundation of Guangdong Province of China,No.EF017/FHS-YZ/2021/GDSTC(to ZY)。
文摘To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.
基金Project supported by the National Natural Science Foundation of China (No. 30771553)the Basic Research Foundation for Science and Technology of Nanjing Agricultural University,China
文摘The O subfamily of forkhead box(FoxO) proteins is the downstream effector of the insulin-like growth factor-1/phosphoinositide 3-kinase/protein kinase B(IGF-1/PI3K/PKB) signal pathway.The objective of the present study was to examine the expressions of three members of FoxO proteins,FoxO1,FoxO3a,and FoxO4 in the duodenum of Sprague-Dawley rats at different ages.The result demonstrated that the expression of FoxO4 in rat duodenum showed an age-dependent manner.At Day 21,there were no detectable localization and expression of FoxO4 in the duodenum,while,at Months 2 and 6,localization and expression of FoxO4 were distinct.In addition,FoxO4 staining was primarily concentrated in the cell nuclei of the lamina propria around the intestinal gland of the duodenum in 2-month-old rats,but was not detectable in the same area in 6-month-old rats.Our results showed also that although FoxO3a existed in the cytoplasm of the lamina propria at a low level at the 2-and 6-month marks,it was still not detectable at Day 21.Besides,FoxO1 was not detectable in all parts and stages.Taken together,our findings suggested that the cell-specific and age-dependent expressional patterns of FoxO4 and FoxO3a proteins in the duodenum play some roles in the development and growth performance of the rat duodenum.
文摘A SEI model for hepatitis B is constructed where the susceptibility and other crucial transmission probabilities depend on the chronological age and the basic reproduction rate R0 is derived. Under suitable (biological and mathematical) assumptions in a closed population, results of Houpa D. D. E. et al. [1] are extended from constant case of p and q to age-dependent case: the disease-free equilibrium is globally asymptotically stable (GAS) if R0 . On the other hand, R0 > 1 induces that endemic equilibrium is GAS and the system is uniformly persistent.
文摘Objective To verify whether peripheral blood circulation and arterial wall distensibility are influenced by atmospheric pressure （AtPr） and to examine if their association is dependent on age and/or sex. Methods Associations among natural AtPr levels （on the examination day as well as 1 and 2 days prior）, limb muscle hemodynamics, and distensibility of conduit arteries were retrospectively examined in an observational study of 276 untreated patients with primary moderate hypertension （mean age 56.4 years, 194 men）. Forearm and calf circulations at rest and 3 min after ischemia were measured by venous occlusion plethysmography. Compliance of the brachial and shank arteries was assessed by oscillometry. Results After adjustment for age, degree of hypertension, and season, correlation and multiple resression analyses revealed a season-independent but age-dependent direct correlation between the stiffness of limb arteries and AtPr levels on the examination day in men, but not women. The association weakened with the degree of hypertension, disappeared with age, and was more evident in the arms than in the legs. Conclusion Parameters of arterial wall distensibility in adult hypertensive men are susceptible to AtPr changes within the usually observed limits （730-770 mmHg）. It is proposed that reduction of arterial wall barometric responsiveness in women and aging men is a likely mechanism underlying their meteosensitivity.
文摘In this and upcoming papers,the authors investigate optimal policies for two age-dependent populations with the interaction of predator and prey,which is described by an integro-differential system and controlled by fertility.As the starting point of research,this article is mainly devoted to the well-posedness of basic model by means of contraction mapping principle.
文摘Crohn’s disease is a chronic inflammatory disease process involving different sites in the gastrointestinal tract. Occasionally, so-called metastatic disease occurs in extra-intestinal sites. Granulomatous inflammation may be detected in endoscopic biopsies or resected tissues. Genetic, epigenetic and environmental factors appear to play a role. Multiple susceptibility genes have been described in both familial and non-familial forms while the disease is phenotypically heterogeneous with a female predominance. The disorder occurs over a broad age spectrum, from early childhood to late adulthood. More than 80% are diagnosed before age 40 years usually with terminal ileal and colonic involvement. Pediatric-onset disease is more severe and more extensive, usually with a higher chance of upper gastrointestinal tract disease, compared to adult-onset disease. Long-term studies have shown that the disorder may evolve with time into more complex disease with stricture formation and penetrating disease complications (i.e., fistula, abscess). Although prolonged remission may occur, discrete periods of symptomatic disease may re-appear over many decades suggesting recurrence or re-activation of this inflammatory process. Eventual development of a cure will likely depend on identification of an etiologic cause and a fundamental understanding of its pathogenesis. Until now, treatment has focused on removing risk factors, particularly cigarette smoking, and improving symptoms. In clinical trials, clinical remission is largely defined as improved numerical and endoscopic indices for “mucosal healing”. “Deep remission” is a conceptual, more “extended” goal that may or may not alter the long-term natural history of the disease in selected patients, albeit at a significant risk for treatment complications, including serious and unusual opportunistic infections.
文摘Crohn’s disease is a chronic inflammatory granulomatous process that usually involves different sites in the intestinal tract. Genetic and environmental factors are thought to play a role in its etiology and pathogenesis. The disorder has a heterogeneous clinical expression and data from tertiary care settings have documented its female predominance, occasional familial nature, and high rate of stricture formation and penetrating disease. It may appear from early childhood to late adulthood, although over 80% are currently diagnosed before age 40 years, usually with terminal ileal and colonic involvement. Several studies have now shown differences in phenotypic clinical expression depending on the initial age at diagnosis, with pediatric-onset disease being more severe and more extensive with more involvement of the upper gastrointestinal tract compared to adult-onset disease. In addition, long- term studies from these tertiary care settings have documented that the disorder may evolve with time into a more complex disease with stricture formation and penetrating disease complications (i.e. fistula and abscess). Although prolonged remission with no evidence of inflammatory disease may occur, discrete periods of symptomatic and active granulomatous inflammatory disease may re-appear over many decades. Long-term studies on the natural history have also suggested that discrete events (or agents) may precipitate this granulomatous inflammatory process.
基金supported by the National Natural Science Foundation of China (81371400 and 81071026)the National Basic Research Development Program of China (2013CB530900)the Key Discipline of Chongming County and Shanghai Institute of Health Science, China (FY(14)700-A5-1-19)
文摘The negative-geotaxis climbing assay is used to efficiently study aging and neurodegeneration in Drosophila.To make it suitable for large-scale study,a method called the rapid iterative negative geotaxis（RING） assay has been established by simultaneously photographing the climbing of multiple groups of flies when they are manually tapped down in test tubes.Here,we automated the assay by using a well-controlled electric motor to drive the tapping,and a homemade program to analyze the climbing height of flies.Using the automated RING（aRING） assay,we found that the climbing ability of a strain of wild-type flies,males in particular,declined rapidly before day 21 after eclosion,but slowly from day 21 to 35.We also found that the expression of arctic mutant Aβ_（42） accelerated the age-dependent decline in the climbing ability of flies.Moreover,using aRING,we examined the effect of third chromosome deficiencies on the accelerated locomotor decline in Aβ_（42）-expressing flies,and isolated 7 suppressors and15 enhancers.
文摘The German waltzing guinea pig is a strain of animals expressing deafness and severe balance disorders at birth.The mutation arose spontaneously in a breeding facility in Germany and as the affected animals show a characteristic waltzing behavior,the strain is named the German waltzing guinea pig.The strain is presently bred only at Karolinska Institutet.The hereditary inner ear impairment has a recessive mode of inheritance and the strain thus produces not only affected homozygotes but also symptom-free heterozygotes and fully normal offspring.The outcome depends solely on the genotype of the parents.The heterozygotes,which have obtained the 'waltzing' gene from one parent only,have normal hearing and no balance dysfunction.The heterozygous animals appear normal but will,in turn,carry the genetic defect to the next generation.The present thesis is focused on these animals.Noise and ototoxic drugs are well known stress factors that interfere negatively with the hearing organ in both humans and animals,causing hearing impairment.However,the inter-individual variability in susceptibility to auditory stress factors is surprisingly large,most likely due to different genetic predisposition.In this study,heterozygous animals of the German waltzing guinea pig,animals carrying a genetic defect known to cause severe hearing impairment,were used to study how an unexplored gene for deafness interacts with auditory stress agents,i.e.noise exposure and the ototoxic drugs gentamicin and cisplatin.Animals were exposed to both narrowband as well as broadband noise at different ages and hearing thresholds were measured using ABRs.Heterozygotes of the German waltzing guinea pig showed less threshold shifts compared to control strains.Older animals were less affected by the noise trauma than younger animals.To test the hypothesis that the efferent system contributes to protection of the inner ear against noise trauma,measurements using a new method of post onset adaptation of DPOAEs and maximum adaptation magnitude were conducted.The post onset adaptation of DPOAEs detected a strain difference at the higher frequency region while in the maximum adaptation magnitude method showed no difference between the strains.The heterozygous German waltzing guinea pigs displayed a distinctly increased resistance to noise exposures,manifested as reduced threshold shifts and faster recovery following acoustic overstimulation.However,when exposed to ototoxic drugs,the heterozygous carriers suffered from a more pronounced hearing loss.It is concluded that endogenous resistance to noise in the heterozygotes does not offer any protection against ototoxic drugs.The detailed mechanisms remain to be explored.
文摘In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional derivatives.As a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional calculus.We establish the existence of a unique solution of the given model with the given initial conditions.At last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.
基金The work is supported by‘Qing Lan’Talent Engineering Funds(QL-05-1SA) by Lanzhou Jiaotong Universitythe National Natural Science Foundation of China under Grant No.604730304.
文摘In this paper, we investigate optimal policies for an age-dependent n-dimensional competition system, which is controlled by fertility. By using Dubovitskii-Milyutin＇s general theory, the maximum principles are obtained for the problems with free terminal states, infinite horizon, and target sets, respectively.
基金Acknowledgments This work is supported by the Nature Science Foundation of China （11061017） and the Nature Science Foundation of Gansu Province of China （1010RJZA075）.
文摘This paper is concerned with an optimal harvesting problem over an infinite horizon for age-dependent n-dimensional food chain model and the analysis of long-term behaviors of the optimal-controlled system. The existence of overtaking optimal policy is proved and a maximum principle is carefully derived by means of Dubovitskii-Milyutin functional analytical extremum theory. Weak and strong turnpike properties of optimal trajectories are established.
基金the National Natural Sciente Foundation of China (Grant Nos. 10771021, 10471012)Scientific Research Foundation for Returned Scholars, Ministry of Education of China (Grant No. [2005]564)
文摘We consider an age-dependent branching process in random environments. The environments are represented by a stationary and ergodic sequence ξ = (ξ 0, ξ 1,…) of random variables. Given an environment ξ, the process is a non-homogenous Galton-Watson process, whose particles in n-th generation have a life length distribution G(ξ n ) on ?+, and reproduce independently new particles according to a probability law p(ξ n ) on ?. Let Z(t) be the number of particles alive at time t. We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation, and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process. We then get expressions of the conditional mean E ξ Z(t) and the global mean EZ(t), and show their exponential growth rates by studying a renewal equation in random environments.
基金Supported by Major Innovation Projects for Building First-class Universities in China’s Western Region(No.ZKZD2017009)(China)
文摘In this paper, we present the compensated stochastic θ method for stochastic age-dependent delay population systems（SADDPSs） with Poisson jumps. The definition of mean-square stability of the numerical solution is given and a sufficient condition for mean-square stability of the numerical solution is derived. It is shown that the compensated stochastic θ method inherits stability property of the numerical solutions. Finally,the theoretical results are also confirmed by a numerical experiment.
文摘The cohort study by Li et al provides timely and clinically relevant evidence on the use of recombinant human thrombopoietin(rhTPO)in pediatric allogeneic hematopoietic stem cell transplantation.The authors report enhanced platelet engraftment and a favorable safety profile,particularly in younger children aged 0-9 years.This age-dependent difference not only highlights the physiological responsiveness of early hematopoietic environments to rhTPO but also raises important questions about tailoring supportive therapies across pediatric age groups.While the findings are promising,the lack of a control group and single-center limitations warrant further multicenter,long-term investigations.Ne-vertheless,the study lays a compelling foundation for integrating rhTPO more broadly into pediatric transplant protocols and for advancing individualized post-transplant care.
文摘This paper is concerned with optimal harvesting control of a first order partial differential equation system representing a nonlinear n-dimensional competitive population model with age-structure. By the Ekeland＇s variational principle, the existence and unique char- acterization of the optimal control strategy are established. The optimality conditions for the control problem are obtained by the concept of the normal cone.
基金This research is supported by the National Natural Science Foundation of China.
文摘In recent years, population growth models with spatial diffusion have beenextensively studied by many authors (for example, see [1-5]). In this paper, a populationgrowth model is considered with a discrete age-dependence and spatial diffusion, and isinvestigated in a semigroup framework. The spectral properties of the population oper-ator are given. On the basis of such spectral consideration, the asymptotic behaviourof the semigroup generated by the population operator is obtained. Finally, a nonlinearpopulation growth model is considered and its stability is analyzed.
