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1.
In this work,we have introduced an eco-epidemiological model of an infected predator prey system.Incorporation of prey refuge gives that a fraction of the infected prey is available to the predator for consumption.Moreover,to make the model more realistic to the environment,we have introduced strong Allee effect in the susceptible population.Boundedness and positivity of the solution have been established.Local stability conditions of the equilibrium points have been found with the help of Routh-Hurwitz criterion and it has been observed that if a prey population is infected with a lethal disease,then both the prey(susceptible and infected)and predator cannot survive simultaneously in the system for any parametric values.The disease transmission rate and the attack rate on the susceptible have an important role to control the system dynamics.For different values of these two key parameters,we have got only healthy or disease-free or predation-free or a fluctuating disease-free or even a fluctuating predator-free system with some certain parametric conditions.  相似文献   

2.
The response of copper metabolism to dietary copper challenge was investigated in jaundiced rats with elevated plasma concentrations of conjugated bilirubin as a result of impaired canicular transport of bilirubin glucuronides. Control and jaundiced rats were fed purified diets with either normal (64 μmol Cu/kg) or high (640 μmol Cu/kg) concentration of added copper. Copper loading produced a greater increase in hepatic copper concentrations in the jaundiced than in control rats. The greater dietary-copper-induced increase in hepatic copper in the jaundiced rats can be explained by the observed smaller rise in biliary copper excretion and a greater efficiency of dietary copper absorption. In individual rats, there was a positive relationship between hepatic copper concentrations and biliary copper concentrations. It is suggested that not the transport of copper from liver cells to bile but that from plasma to bile is diminished in the jaundiced rats. The elevated plasma copper concentrations in the jaundiced rats may support this suggestion.  相似文献   

3.
Fertilizer N use in Japan has decreased by about 30% from 1960 to 2000, while keeping a little increase in cereal yields. This has resulted in a significant increase in apparent nitrogen use efficiency, in particular for rice. On the other hand, national N load on the environment associated with the production and consumption of domestic and imported agricultural products has almost tripled during this period, mainly due to the dramatic increase of imports of food and feedstuffs. The environmental problems, including water and air pollution, caused by the excessive loads of N are serious public concerns and there is an urgent need to minimize N losses from agricultural production. In order to meet the necessity for reducing the environmental impacts by excess N, political and technological measures have been taken at regional and country levels. In recent years, the Japanese government has embarked on a series of policies to encourage transition to an environmentally conscious agriculture. Promoting proper material circulation with reducing fertilizer impact and utilizing biomass and livestock wastes is emphasized in these policies. The effectiveness of environmental assessment and planning for reducing regional and national N load has been discussed. Implementation of environmentally friendly technologies and management, both conventional and innovational, have been developed and adopted in Japanese agriculture. The effectiveness of conventional technologies in reducing environmental reactive N has been re-evaluated. Innovative technologies, such as use of controlled availability fertilizers and livestock wastes compost pellets, are being investigated and extended. A comprehensive approach that applies political and technological measures with closer cooperation is necessary to control reactive N in the environment.  相似文献   

4.
DNA damaged by oxygen radicals has been implicated as a causative event in a number of degenerative diseases, including cancer and aging. So it is very impotant to look for ways in which either oxygen radicals are scavenged prior to DNA damage or damaged DNA is repaired to supplement the cells' inadequate repair capacity. The repair activity and its mechanism of verbaseoside, isolated from Pedicularis species, towards dAMP-OH·was studied with pulse radiolytic technique. On pulse irradiation of nitrous oxide saturated 2 mmol/L dAMP aqueous solution containing verbascoside, the transient absorption spectrum of the hydroxyl adduct of dAMP decayed with the formation of that of the phenoxyl radical of verbascoside well under 100 microseconds after electron pulse irradiation. The result indicated that dAMP hydroxyl adducts can be repaired by verbascoside. The rate constants of the repair reaction was deduced to be 5.9×10~8 dm~3·mol~(-1)·s~(-1). A deeper understanding of this new repair mechanism will undo  相似文献   

5.
The extracellular matrix-associated bone morphogenetic proteins(BMPs) govern a plethora of biological processes. The BMPs are members of the transforming growth factor-β protein superfamily, and they actively participate to kidney development, digit and limb formation, angiogenesis, tissue fibrosis and tumor development. Since their discovery, they have attracted attention for their fascinating perspectives in the regenerative medicine and tissue engineering fields. BMPs have been employed in many preclinical and clinical studies exploring their chondrogenic or osteoinductive potential in several animal model defects and in human diseases. During years of research in particular two BMPs, BMP2 and BMP7 have gained the podium for their use in the treatment of various cartilage and bone defects. In particular they have been recently approved for employment in non-union fractures as adjunct therapies. On the other hand, thanks to their potentialities in biomedical applications, there is a growing interest in studying the biology of mesenchymal stem cell(MSC), the rules underneath their differentiation abilities, and to test their true abilities in tissue engineering. In fact, the specific differentiation of MSCs into targeted celltype lineages for transplantation is a primary goal of the regenerative medicine. This review provides an overview on the current knowledge of BMP roles and signaling in MSC biology and differentiation capacities. In particular the article focuses on the potential clinical use of BMPs and MSCs concomitantly, in cartilage and bone tissue repair.  相似文献   

6.
Zinc (Zn) and copper (Cu) concentrations in hair and urine of patients diagnosed and hospitalized for myocardial infarction (MI patients) and in their descendants (MI descendants) were estimated and compared with their age-matched healthy volunteers with no family history of MI (control group and control descendants). The data revealed approximately twofold higher Zn and twofold lower Cu in the urine of the patients; Zn was lower and Cu was higher in the urine of MI descendants than those of the patients (p<0.001), but Zn in hair and urine was higher and Cu in hair was lower in MI descendants compared with their control counterparts (p<0.001). The data suggested that there was a consistent rise in Zn and fall in Cu reserves in the genetically predisposed subjects (MI descendants) prior to the manifestation of clinical symptoms. Based on this, the data were subjected to logistic regression and a model was obtained to predict the susceptibility to MI (LR-MI), having impact factors values as follows: constant (C), −3.342; impact factor of body mass index, −0.776; impact factor of hair Zn, −2.449; impact factor of urine Zn, +3.441; impact factor of hair Cu, −15.077; impact factor of urine Cu, −24.153. For the equation Y=e x (1+e x ), the value of x was obtained as follows: −3.342+[BMI (kg/m2) (−0.776)]+[Hair Zn (μmol/g) (−2.449)]+[Urine Zn (μmol/L) (3.441)]+[Hair Cu (μmol/g) (−15.077)]+[Urine Cu (μmol/L) (−24.153)]. On substituting the values of BMI, hair Zn, urine Zn, hair Cu, and urine Cu in x, the response variable Y as zero for healthy controls and 0.99 or 99.9% susceptibility in MI patients were obtained. In between these two extremes, the response variable ranged between 0 and 0.99 or 99.9% susceptibility to MI in their descendants. It is envisaged that the MI patients have an operational component of a genetic disorder of ionic imbalance at a young age that can be exploited in making a prediction of susceptibility to heart stroke in individuals much before its onset and diagnosis in asymptomatic patients, particularly in genetic and epidemiological studies of MI.  相似文献   

7.
The effect of lignin containing natural substrates corn-cob, coir-dust, saw-dust, wheat straw and bagasse particles on the extracellular secretion of laccase in the liquid culture growth medium of Pleurotus sajor-caju MTCC 141 has been studied. The culture conditions for maximum secretion of laccase by Pleurotus sajor-caju MTCC 141 have been optimized. Homogeneous preparation of laccase from the culture filtrate of the fungus has been achieved using ammonium sulphate precipitation, anion exchange chromatography on DEAE and gel filtration chromatography on Sephadex G-100. The purified enzyme preparation gave a single protein band in SDS-PAGE analysis indicating a molecular weight of 90 kD. The enzymatic characteristics Km, kcat, pH and temperature optima of the purified laccase have been determined using 2, 6-dimethoxyphenol as the substrate and have been found to be 35μmol/L, 0.30 min-1, 4.5 and 37℃ respectively. The Km values for the other substrate like catechol, m-cresol, pyrogallol and syringaldazine have also been determined which were found to be 216 μmol/L, 380 μmol/L, 370 μmol/L and 260 μmol/L respectively.  相似文献   

8.
Computer-aided protein-coding gene prediction in uncharacterized genomic DNA sequences is one of the most important issues of biological signal processing.A modified filter method based on a statistically optimal null filter(SONF) theory is proposed for recognizing protein-coding regions.The square deviation gain(SDG) between the input and output of the model is used to identify the coding regions.The effective SDG amplification model with Class I and Class II enhancement is designed to suppress the non-coding regions.Also,an evaluation algorithm has been used to compare the modified model with most gene prediction methods currently available in terms of sensitivity,specificity and precision.The performance for identification of protein-coding regions has been evaluated at the nucleotide level using benchmark datasets and 91.4%,96%,93.7% were obtained for sensitivity,specificity and precision,respectively.These results suggest that the proposed model is potentially useful in gene finding field,which can help recognize protein-coding regions with higher precision and speed than present algorithms.  相似文献   

9.
We consider a deterministic model of Zika and Dengue viruses co-circulating in a human population. We study the system of differential equations modeling the dynamics of the diseases that can either be transmitted directly (host-to-host) or indirectly (host-vectorhost).We use an SIR model for hosts and an SI model for vectors in the homogeneous populations. The stability of the model has been analyzed both qualitatively and quantitatively.  相似文献   

10.
The use of orthobiologics as a novel therapy for the treatment of numerous musculoskeletal disorders has increased considerably over the past decade.Currently,there are multiple alternatives available as suitable treatments;however,the use of autologous blood-derived products such as platelet-rich plasma(PRP),bone marrow aspirate(BMA)and BMA concentrate(BMAC),specifically,is expanding.Although many investigations attempted to demonstrate the effectiveness of these therapies,even with positive results,the literature lacks standardized protocols and overall accuracy in study designs,which leads to variance and difficulty in reproducibility of protocols.The efficacy of PRP for the treatment of cartilage,bone and muscle tissues is well known.Although BMAC has generated optimistic results for the same purposes,its applicability in clinical trials is still relatively recent when compared to PRP.Both products demonstrate the potential to set forth reparative processes,each in their own distinct mechanism.The combination of these biological products has been previously proposed,yet little is known about their synergism.Evidence indicates that growth factor,cytokine,and chemokine profiles seen in both PRP and BMAC vary but are likely to work synergistically to enhance musculoskeletal healing.BMAC products seem to work well without PRP;however,the addition of PRP to BMAC has been shown to act as a rich and natural source of culture medium for stem cells located either peripherally or in the bone marrow itself.Nevertheless,additional variables associated with the use of BMAC and PRP in orthopedics must be further evaluated in order to consolidate the efficacy of this therapeutic strategy.  相似文献   

11.
《Ecological monographs》2011,81(4):581-598
The complexity of mathematical models of ecological dynamics varies greatly, and it is often difficult to judge what would be the optimal level of complexity in a particular case. Here we compare the parameter estimates, model fits, and predictive abilities of two models of metapopulation dynamics: a detailed individual-based model (IBM) and a population-based stochastic patch occupancy model (SPOM) derived from the IBM. The two models were fitted to a 17-year time series of data for the Glanville fritillary butterfly (Melitaea cinxia) inhabiting a network of 72 small meadows. The data consisted of biannual counts of larval groups (IBM) and the annual presence or absence of local populations (SPOM). The models were fitted using a Bayesian state-space approach with a hierarchical random effect structure to account for observational, demographic, and environmental stochasticities. The detection probability of larval groups (IBM) and the probability of false zeros of local populations (SPOM) in the observation models were simultaneously estimated from the time-series data and independent control data. Prior distributions for dispersal parameters were obtained from a separate analysis of mark–recapture data. Both models fitted the data about equally, but the results were more precise for the IBM than for the SPOM. The two models yielded similar estimates for a random effect parameter describing habitat quality in each patch, which were correlated with independent empirical measures of habitat quality. The modeling results showed that variation in habitat quality influenced patch occupancy more through the effects on movement behavior at patch edges than on carrying capacity, whereas the latter influenced the mean population size in occupied patches. The IBM and the SPOM explained 63% and 45%, respectively, of the observed variation in the fraction of occupied habitat area among 75 independent patch networks not used in parameter estimation. We conclude that, while carefully constructed, detailed models can have better predictive ability than simple models, this advantage comes with the cost of greatly increased data requirements and computational challenges. Our results illustrate how complex models can be helpful in facilitating the construction of effective simpler models.  相似文献   

12.
Articular cartilage damage and osteoarthritis (OA) are common orthopedic diseases in both humans and dogs. Once damaged, the articular cartilage seldom undergoes spontaneous repair because of its avascular, aneural, and alymphatic state, and the damage progresses to a chronic and painful situation. Dogs have distinctive characteristics compared to other laboratory animal species in that they share an OA pathology with humans. Dogs can also require treatment for naturally developed OA;therefore, effective treatment methods for OA are desired in veterinary medicine as well as in human medicine. Recently, interest has grown in regenerative medicine that includes the use of mesenchymal stem cells (MSCs). In cartilage repair, MSCs are a promising therapeutic tool due to their self-renewal capacity, ability to differentiate into cartilage, potential for trophic factor production, and capacity for immunomodulation. The MSCs from dogs (canine MSCs;cMSCs) share various characteristics with MSCs from other animal species, but they show some deviations, particularly in their differentiation ability and surface epitope expression. In vivo studies of cMSCs have demonstrated that intraarticular cMSC injection into cartilage lesions results in excellent hyaline cartilage regeneration. In clinical situations, cMSCs have shown great therapeutic effects, including amelioration of pain and lameness in dogs suffering from OA. However, some issues remain, such as a lack of regulations or guidelines and a need for unified methods for the use of cMSCs. This review summarizes what is known about cMSCs, including their in vitro characteristics, their therapeutic effects in cartilage lesion treatment in preclinical in vivo studies, their clinical efficacy for treatment of naturally developed OA in dogs, and the current limitations of cMSC studies.  相似文献   

13.
In recent years, research in life sciences has been remarkably revolutionized owing to the establishment, development and application of genome editing technologies. Genome editing has not only accelerated fundamental research but has also shown promising applications in agricultural breeding and therapy. In particular, the clustered, regularly interspaced, short palindromic repeat (CRISPR) technology has become an indispensable tool in molecular biology owing to its high efficacy and simplicity. Genome editing tools have also been established in silkworm (Bombyx mori), a model organism of Lepidoptera insects with high economic importance. This has remarkably improved the level and scope of silkworm research and could reveal new mechanisms or targets in basic entomology and pest management studies. In this review, we summarize the progress and potential of genome editing in silkworm and its applications in functional genomic studies for generating novel genetic materials.  相似文献   

14.
The RecFOR DNA repair pathway is one of the major RecA-dependent recombinatorial repair pathways in bacteria and plays an important role in double-strand breaks repair. RecO, one of the major recombination mediator proteins in the RecFOR pathway, has been shown to assist RecA loading onto single-stranded binding protein (SSB) coated single-stranded DNA (ssDNA). However, it has not been characterized whether the protein-protein interaction between RecO and SSB contributes to that process in vivo. Here, we identified the residue arginine-121 of Deinococcus radiodurans RecO (drRecO-R121) as the key residue for RecO-SSB interaction. The substitution of drRecO-R121 with alanine greatly abolished the binding of RecO to SSB but not the binding to RecR. Meanwhile, SSB-coated ssDNA annealing activity was also compromised by the mutation of the residue of drRecO. However, the drRecO-R121A strain showed only modest sensitivity to DNA damaging agents. Taking these data together, arginine-121 of drRecO is the key residue for SSB-RecO interaction, which may not play a vital role in the SSB displacement and RecA loading process of RecFOR DNA repair pathway in vivo.  相似文献   

15.
Fish finders have already been widely available in the fishing market for a number of years.However,the sizes of these fishfinders are too big and their prices are expensive to suit for the research of robotic fish or mini-submarine.The goal of thisresearch is to propose a low-cost fish detector and classifier which suits for underwater robot or submarine as a proximity sensor.With some pre-condition in hardware and algorithms,the experimental results show that the proposed design has good per-formance,with a detection rate of 100 % and a classification rate of 94 %.Both the existing type of fish and the group behaviorcan be revealed by statistical interpretations such as hovering passion and sparse swimming mode.  相似文献   

16.
Recent advances in our ability to design DNA binding factors with specificity for desired sequences have resulted in a revolution in genetic engineering, enabling directed changes to the genome to be made relatively easily. Traditional techniques for generating genetic mutations in most organisms have relied on selection from large pools of randomly induced mutations for those of particular interest, or time-consuming gene targeting by homologous recombination. Drosophila melanogaster has always been at the forefront of genetic analysis, and application of these new genome editing techniques to this organism will revolutionise our approach to performing analysis of gene function in the future. We discuss the recent techniques that apply the CRISPR/Cas9 system to Drosophila, highlight potential uses for this technology and speculate upon the future of genome engineering in this model organism.  相似文献   

17.
18.
Portal vein thrombosis (PVT) is a common complication of liver cirrhosis. Gao et al. [1] reported that the prevalence of PVT in patients with cirrhosis is 8.82%. With the rapid developments in image-based diagnostic technology, the diagnosis rate of PVT is gradually increasing [2]. A follow-up study of 1243 patients with cirrhosis revealed that the cumulative incidences of PVT at 1, 3, and 5 years are 4.6%, 8.2%, and 10.7%, respectively [3]. PVT is a life-threatening factor for patients with cirrhosis, leading to portal hypertension and aggravating gastrointestinal hemorrhage [4]. The prevention of PVT has become a focus of clinical concern nowadays. It is well known that the establishment of animal models is the basis of scientific research. However, it is currently difficult to establish PVT models in large animals. Thereby, the establishment of a stable PVT animal model to study PVT is urgent and significant. We successfully established a new canine model of PVT involving the injection of an autologous thrombus through an indwelling catheter in the portal vein. This model is reliable for further studies of surgical treatment and drug therapy for PVT.  相似文献   

19.
The muscle protein myosin binding protein C (MyBPC) is a large multi-domain protein whose role in the sarcomere is complex and not yet fully understood. Mutations in MyBPC are strongly associated with the heart disease familial hypertrophic cardiomyopathy (FHC) and these experiments of nature have provided some insight into the intricate workings of this protein in the heart. While some regions of the MyBPC molecule have been assigned a function in the regulation of muscle contraction, the interaction of other regions with various parts of the myosin molecule and the sarcomeric proteins, actin and titin, remain obscure. In addition, several intra-domain interactions between adjacent MyBPC molecules have been identified. Although the basic structure of the molecule (a series of immunoglobulin and fibronectin domains) has been elucidated, the assembly of MyBPC in the sarcomere is a topic for debate. By analysing the MyBPC sequence with respect to FHC-causing mutations it is possible to identify individual residues or regions of each domain that may be important either for binding or regulation. This review looks at the current literature, in concert with alignments and the structural models of MyBPC, in an attempt to understand how FHC mutations may lead to the disease state.  相似文献   

20.
Although apoptosis has been recently documented to transmit immunosuppressive signals, their significance in allogeneic transplantation has not been reported. In the present study, we investigated the influence of donor apoptotic splenocytes on allograft survival in a SD to Wistar rat cardiac transplant model. Donor splenocytes were isolated and irradiated with ultraviolet (UV) to induce apoptosis in vitro. 5x107 apoptotic, necrotic or untreated donor spleen cells were transfused preoperatively and cardiac allogeneic transplantation  相似文献   

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