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Moein Khalighi Guilhem Sommeria-Klein Didier Gonze Karoline Faust Leo Lahti 《PLoS computational biology》2022,18(6)
Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications.Recent modeling studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can be introduced in such models using the framework of fractional calculus. We study how the dynamics of a well-characterized interaction model is affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity.Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory introduces inertia into the dynamics. This favors species coexistence under perturbation, enhances system resistance to state shifts, mitigates hysteresis, and can affect system resilience both ways depending on the time scale considered. Memory also promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Our study highlights the fundamental role of memory in communities, and provides quantitative tools to introduce it in ecological models and analyse its impact under varying conditions. 相似文献
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Omid Reza Tamtaji Moein Mobini Russel J. Reiter Abolfazl Azami Mohammad Saeed Gholami Zatollah Asemi 《Journal of cellular physiology》2019,234(6):7788-7795
Toll-like receptors (TLRs) are crucial activators of inflammatory responses, they are considered immune receptors. TLRs are of fundamental importance in the pathophysiology of disorders related to inflammation including neurodegenerative diseases and cancer. Melatonin is a beneficial agent in the treatment of inflammatory and immune disorders. Melatonin is potent anti-inflammatory hormone that regulates various molecular pathways. Withal, limited studies have evaluated the inhibitory role of melatonin on TLRs. This review summarizes the current knowledge related to the effects of melatonin on TLRs in some common inflammatory and immunity disorders. 相似文献
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Soheila Moein Mostafa Vaghari-Tabari Durdi Qujeq Maryam Majidinia Seyed Mohammad Nabavi Bahman Yousefi 《Journal of cellular physiology》2019,234(4):3277-3293
Inflammatory bowel disease (IBD), as a chronic and recurrent inflammatory disorder, is caused by a dysregulated and aberrant immune response to exposed environmental factors in genetically susceptible individuals. Despite huge efforts in determining the molecular pathogenesis of IBD, an increasing worldwide incidence of IBD has been reported. MicroRNAs (miRNAs) are a set of noncoding RNA molecules that are about 22 nucleotides long, and these molecules are involved in the regulation of the gene expression. By clarifying the important role of miRNAs in a number of diseases, their role was also considered in IBD; numerous studies have been performed on this topic. In this review, we attempt to summarize a number of studies and discuss some of the recent developments in the roles of miRNAs in the pathophysiology, diagnosis, and treatment of IBD. 相似文献
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Al-Hanbali O Onwuzo NM Rutt KJ Dadswell CM Moghimi SM Hunter AC 《Analytical biochemistry》2007,361(2):287-293
Block copolymers are increasingly being applied in areas such as transfection, membrane sealing, site-specific targeting, and bionanoengineering yet there is a relative paucity of assays available for simple, stable and reproducible colorimetric determination of copolymer concentration in solution. We have focused on improving the accuracy and reproducibility of a modified version of the Stewart biphasic colorimetric assay for quantitative determination of Pluronic (poloxamer) and Tetronic (poloxamine) macromolecules. The optimized assay achieved linear response ranges in chloroform for commonly used copolymers such as poloxamine 904 (20-300 microg/ml), poloxamine 908 (10-400 microg/ml), poloxamer 402 (20-400 microg/ml), and poloxamer 407 (10-400 microg/ml). Variation in the type of chlorinated solvent used significantly increased assay sensitivity, presumably through macromolecular reorientation, affording increased access for copolymer-ferrothiocyanate complexation. This was found to be optimally favored by the planar geometry of the solvent cis 1,2-dichloroethylene. For application to biological systems copolymer-protein interactions were for the first time determined and were found to be dependent on the fraction of hydrophobic constituents of the block copolymers and protein type. For instance serum albumin was found to interact with copolymers of low hydrophilic-lipophilic balance values and poly(propylene oxide) contaminants, whereas this interaction was not significant with the relatively hydrophilic IgG. In such systems the colorimetric assay directly determines the fraction of unbound (free) copolymer in the presence of proteins. 相似文献
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Moein MM Javanbakht M Akbari-Adergani B 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(11-12):777-782
In this paper, a novel method is described for automated determination of dextromethorphan in biological fluids using molecularly imprinted solid-phase extraction (MISPE) as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and dextromethorphan as template molecule. These imprinted polymers were used as solid-phase extraction sorbent for the extraction of dextromethorphan from human plasma samples. Various parameters affecting the extraction efficiency of the MIP cartridges were evaluated. The high selectivity of the sorbent coupled to the high performance liquid chromatographic system permitted a simple and rapid analysis of this drug in plasma samples with limits of detection (LOD) and quantification (LOQ) of 0.12 ng/mL and 0.35 ng/mL, respectively. The MIP selectivity was evaluated by analyzing of the dextromethorphan in presence of several substances with similar molecular structures and properties. Results from the HPLC analyses showed that the recoveries of dextromethorphan using MIP cartridges from human plasma samples in the range of 1-50 ng/mL were higher than 87%. 相似文献
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In order to determine the extent and causative agents of dermatophytoses in the Hamadan region of West Iran; a study was made during a 9-month period from October 1991 to June 1992. A total of 7495 individuals were studied of whom 681 (9%) were suspect of having cutaneous mycoses. Among them dermatophytoses were the commonest infections (259/681=38%). Of 259 individuals infected with dermatophytes, tinea capitis were observed in 163 (62.9%); t. corporis in 27 (10.4%); t. manuum and t. cruris in 19 (7.3%) each; t. barbae and faciei in 14 (5.4%); t. pedis in 13 (5%) and t. unguium in 4 (1.5%). A total of 144 patients yielded dermatophyte cultures. The frequency of the isolated species in decreasing order was as follows: Trichophyton verrucosum, 78 (54.1%); T. schoenleinii, 48 (33.3%); Microsporum canis, 8 (5.5%); Epidermophyton floccosum, 5 (3.5%); T. mentagrophytes and M. gypseum, 2 (1.4%) each; T. tonsurans, 1 (0.7%). In conclusion, the most prevalent dermatophytosis in this region was t. capitis with the infecting agent of T. schoenleinii. 相似文献
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An efficient strategy for enhancing the lymph node deposition of rapidly drained liposomes from the interstitial injection site is described. Subcutaneously injected small-sized immuno-poly(ethyleneglycol)-liposomes (immuno-PEG-liposomes), containing 10 mol% mPEG350-phospholipid and 1 mol% PEG2000-phospholipid in their bilayer and where IgG1 is coupled to the distal end of PEG2000, not only drain rapidly from the interstitial spaces into the initial lymphatic system, but also accumulate efficiently among the lymph nodes draining the region when compared with non-PEG-bearing immunoliposomes where IgG is directly coupled to the phospholipid. Liposome deposition among the draining lymph nodes, however, was further enhanced dramatically following an adjacent subcutaneous injection of a pentameric IgM against the surface attached IgG molecules (IgM:IgG, 10:1) without compromising vesicle drainage from the interstitium. This is suggested to arise either as a result of formation of large immuno-aggregates within the lymphatic vessels with subsequent transport to and trapping among the regional lymph nodes and/or following IgM binding to Fc receptors of the lymph node sinus macrophages forming a platform for subsequent trapping of drained IgG-coupled liposomes. This lymph node targeting approach may be amenable for the design and surface engineering of any rapidly drained nanoparticulate system bearing peptides and proteins that can be aggregated with a desired monoclonal pentameric IgM. 相似文献
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Masoud Doroodgar Mahdi Delavari Moein Doroodgar Ali Abbasi Ali Akbar Taherian Abbas Doroodgar 《The Korean journal of parasitology》2016,54(1):9-14
Tamoxifen is an antagonist of the estrogen receptor and currently used for the treatment of breast cancer. The current treatment of cutaneous leishmaniasis with pentavalent antimony compounds is not satisfactory. Therefore, in this study, due to its antileishmanial activity, effects of tamoxifen on the growth of promastigotes and amastigotes of Leishmania major Iranian strain were evaluated in vitro. Promastigotes and amastigotes were treated with different concentrations (1, 5, 10, 20, and 50 μg/ml) and time periods (24, 48, and 72 hr) of tamoxifen. After tamoxifen treatment, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5 biphenyl tetrazolium bromide assay) was used to determine the percentage of live parasites and Graph Pad Prism software to calculate IC50. Flow cytometry was applied to investigate the induction of tamoxifen-induced apoptosis in promastigotes. The half maximal inhibitory concentration (IC50) of tamoxifen on promastigotes was 2.6 μg/ml after 24 hr treatment. Flow cytometry analysis showed that tamoxifen induced early and late apoptosis in Leishmania promastigotes. While after 48 hr in control group the apoptosis was 2.0%, the 50 µg/L concentration of tamoxifen increased it to 59.7%. Based on the in vitro antileishmanial effect, tamoxifen might be used for leishmaniasis treatment; however, further researches on in vivo effects of tamoxifen in animal models are needed. 相似文献