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81.
In this paper we study a method for the identification of the unknown parameter of the periodic function and also the first component of the state vector, in a mathematical model which describes the evolution of some diseases with an oro-fecal transmission.To solve the identification problem we use a numerical method to integrate the differential equations system, which reproduces the stability properties of the above mentioned continuous system.The numerical methods which we propose can be applied also to a spatial semi discretization of the reaction-diffusion model which is a diffusive generalization of the system that we consider in this paper.Finally, through an analysis on both the continuous and the discrete system we also obtain a necessary condition on the experimental data in order that a periodic trajectory of the system exists.Work supported by: Progetto Finalizzato Controllo Malattie da Infezione-CNR and by Ministero Pubblica Istruzione 相似文献
82.
Soil Carbon, Nitrogen and Phosphorus Dynamics as Affected by Solarization Alone or Combined with Organic Amendment 总被引:1,自引:0,他引:1
Antonio Gelsomino Luigi Badalucco Loretta Landi Giovanni Cacco 《Plant and Soil》2006,279(1-2):307-325
Soil solarization, alone or combined with organic amendment, is an increasingly attractive approach for managing soil-borne
plant pathogens in agricultural soils. Even though it consists in a relatively mild heating treatment, the increased soil
temperature may strongly affect soil microbial processes and nutrients dynamics. This study aimed to investigate the impact
of solarization, either with or without addition of farmyard manure, in soil dynamics of various C, N and P pools. Changes
in total C, N and P contents and in some functionally-related labile pools (soil microbial biomass C and N, K2SO4-extractable C and N, basal respiration, KCl-exchangeable ammonium and nitrate, and water-soluble P) were followed across
a 72-day field soil solarization experiment carried out during a summer period on a clay loam soil in Southern Italy. Soil
physico-chemical properties (temperature, moisture content and pH) were also monitored. The average soil temperature at 8-cm
depth in solarized soils approached 55 °C as compared to 35 °C found in nonsolarized soil. Two-way ANOVA (solarization×organic
amendment) showed that both factors significantly affected most of the above variables, being the highest influence exerted
by the organic amendment. With no manure addition, solarization did not significantly affect soil total C, N and P pools.
Whereas soil pH, microbial biomass and, at a greater extent, K2SO4-extractable N and KCl-exchangeable ammonium were greatly affected. An increased release of water-soluble P was also found
in solarized soils. Yet, solarization altered the quality of soluble organic residues released in soil as it lowered the C-to-N
ratio of both soil microbial biomass and K2SO4-extractable organic substrates. Additionally, in solarized soils the metabolic quotient (qCO2) significantly increased while the microbial biomass C-to-total organic C ratio (microbial quotient) decreased over the whole
time course. We argued that soil solarization promoted the mineralization of readily decomposable pools of the native soil
organic matter (e.g. the microbial biomass) thus rendering larger, at least over a short-term, the available fraction of some
soil mineral nutrients, namely N and P forms. However, over a longer prospective solarization may lead to an over-exploitation
of labile organic resources in agricultural soils. Manure addition greatly increased the levels of both total and labile C,
N and P pools. Thus, addition of organic amendments could represent an important strategy to protect agricultural lands from
excessive soil resources exploitation and to maintain soil fertility while enhancing pest control. 相似文献
83.
Beswick EJ Pinchuk IV Suarez G Sierra JC Reyes VE 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(11):6794-6801
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that has recently been implicated in carcinogenesis. Helicobacter pylori, which is closely linked to gastric cancer, induces the gastric epithelium to produce proinflammatory cytokines, including MIF. MIF can bind to CD74, which we have previously shown to be highly expressed on the surface of gastric epithelial cells (GEC) during H. pylori infection. In this study, we sought to investigate the role of the H. pylori-induced MIF on epithelial proliferation and procarcinogenic events. Upon establishing a role for the H. pylori CagA virulence factor in MIF production, MIF binding to CD74 on GEC was confirmed. rMIF and H. pylori were shown to increase GEC proliferation, which was decreased when cagA- strains were used and when CD74 was blocked by mAbs. Apoptosis was also decreased by MIF, but increased by cagA- strains that induced much lower amounts of MIF than the wild-type bacteria. Furthermore, MIF binding to CD74 was also shown to decrease p53 phosphorylation and up-regulate Bcl-2 expression. This data describes a novel system in which an H. pylori virulence factor contributes to the production of a host factor that in turn up-regulates procarcinogenic events by the gastric epithelium. 相似文献
84.
Sara Succu Valeria Pasciu Maria E. Manca Sara Chelucci Laura Torres-Rovira Giovanni G. Leoni Angelo Zinellu Ciriaco Carru Salvatore Naitana Fiammetta Berlinguer 《Theriogenology》2014
After cryopreservation, embryos become sensitive to the oxidative stress, resulting in lipid peroxidation, membrane injury, and structural destruction. The present study aimed to assess the effect of increasing concentration of melatonin during postwarming culture on embryo's ability to restore its functions after cryopreservation. In vitro–produced blastocysts were vitrified, warmed, and cultured in vitro in TCM 199 with 5 different supplementations: control (CTR): 10% fetal calf serum; bovine serum albumin (BSA): 0.04% (wt/vol) BSA; and MEL−3, MEL−6, MEL−9: BSA plus melatonin 10−3, 10−6, and 10−9 M. The medium with the highest melatonin concentration had the highest trolox equivalent antioxidant capacity, whose values were comparable with those determined in plasma sampled from adult ewes (8.7 ± 2.4 mM). The other media had lower trolox equivalent antioxidant capacity values (P < 0.01), below the range of the plasma. At the same time, embryos cultured with the highest melatonin concentration reported a lower in vitro viability, as evaluated by lower re-expansion and hatching rates, and lower total cell number compared with the other groups (P < 0.05). Their metabolic status was also affected, as evidenced by higher oxidative and apoptotic index and lower ATP concentration. The beneficial effects of melatonin on embryo development during postwarming culture were observed only at low concentration (10−9 M). These results suggest that melatonin at high concentration may exert some degree of toxic activity on pre-implantation embryos. Thus, the dose at which the embryos are exposed is pivotal to obtain the desiderate effect. 相似文献
85.
Andrea Franzetti Isabella Gandolfi Marco Piscitello Giovanni Porto Adriano Biasiolo Francesca Oltolini Tomaso Marangoni Giuseppina Bestetti 《Biodegradation》2010,21(2):193-201
The effectiveness of biosparging to mitigate N,N diethylaniline in aquifer was evaluated by measuring the time course of decrease in concentration of the aforementioned compound
in aerobic microcosm experiments. The first-order kinetic constant for N,N diethylaniline aerobic biodegradation was estimated from microcosm data (0.037 ± 0.004 d−1), and the value was consistent with the best-fitting value in the transport and reaction model of the aquifer (0.020 d−1). Furthermore, the biodegradability of the compound was evaluated under anaerobic condition in microcosm experiments, which
was supported by field modelling. There was no significant degradation in the anaerobic microcosm experiments, confirming
the recalcitrance of N,N diethyl aniline under the aforementioned aquifer condition. 相似文献
86.
Giovanni Murtas 《Systems and synthetic biology》2010,4(2):85-93
One of the major properties of the semi-synthetic minimal cell, as a model for early living cells, is the ability to self-reproduce itself, and the reproduction of the boundary layer or vesicle compartment is part of this process. A minimal bio-molecular mechanism based on the activity of one single enzyme, the FAS-B (Fatty Acid Synthase) Type I enzyme from Brevibacterium ammoniagenes, is encapsulated in 1-palmitoyl-2oleoyl-sn-glycero-3-phosphatidylcholine (POPC) liposomes to control lipid synthesis. Consequently molecules of palmitic acid released from the FAS catalysis, within the internal lumen, move toward the membrane compartment and become incorporated into the phospholipid bilayer. As a result the vesicle membranes change in lipid composition and liposome growth can be monitored. Here we report the first experiments showing vesicles growth by catalysis of one enzyme only that produces cell boundary from within. This is the prototype of the simplest autopoietic minimal cell. 相似文献
87.
Evidence for two waves of induction of DNA enzymes in stimulated human lymphocytes 总被引:2,自引:3,他引:2 下载免费PDF全文
Guido C. F. Pedrali Noy Leda Dalpra Antonia M. Pedrini Giovanni Ciarrocchi Elena Giulotto Fiorella Nuzzo Arturo Falaschi 《Nucleic acids research》1974,1(9):1183-1199
The stimulation of human lymphocytes with phytohaemoagglutinin induces the appearance or increase of several enzymes of DNA metabolism [Pedrini etal., Biochem. Biophys. Res. Comm., 47:1221(1972)]. With long times of stimulation, two phenomena are observed; an increase in the levels of DNA polymerase, of a DNase acting on single-stranded DNA, and of an endonuclease, occurring between the third and fourth day, in parallel with a wave of DNA synthesis;a second wave of increase of the same enzymes and of DNA ligase,occurring between the fifth and eight day when the DNA replication rate, as measured by thymidine-pulses, has decreased to values close to the background. 相似文献
88.
Girirajan S Brkanac Z Coe BP Baker C Vives L Vu TH Shafer N Bernier R Ferrero GB Silengo M Warren ST Moreno CS Fichera M Romano C Raskind WH Eichler EE 《PLoS genetics》2011,7(11):e1002334
While numerous studies have implicated copy number variants (CNVs) in a range of neurological phenotypes, the impact relative to disease severity has been difficult to ascertain due to small sample sizes, lack of phenotypic details, and heterogeneity in platforms used for discovery. Using a customized microarray enriched for genomic hotspots, we assayed for large CNVs among 1,227 individuals with various neurological deficits including dyslexia (376), sporadic autism (350), and intellectual disability (ID) (501), as well as 337 controls. We show that the frequency of large CNVs (>1 Mbp) is significantly greater for ID-associated phenotypes compared to autism (p = 9.58 × 10(-11), odds ratio = 4.59), dyslexia (p = 3.81 × 10(-18), odds ratio = 14.45), or controls (p = 2.75 × 10(-17), odds ratio = 13.71). There is a striking difference in the frequency of rare CNVs (>50 kbp) in autism (10%, p = 2.4 × 10(-6), odds ratio = 6) or ID (16%, p = 3.55 × 10(-12), odds ratio = 10) compared to dyslexia (2%) with essentially no difference in large CNV burden among dyslexia patients compared to controls. Rare CNVs were more likely to arise de novo (64%) in ID when compared to autism (40%) or dyslexia (0%). We observed a significantly increased large CNV burden in individuals with ID and multiple congenital anomalies (MCA) compared to ID alone (p = 0.001, odds ratio = 2.54). Our data suggest that large CNV burden positively correlates with the severity of childhood disability: ID with MCA being most severely affected and dyslexics being indistinguishable from controls. When autism without ID was considered separately, the increase in CNV burden was modest compared to controls (p = 0.07, odds ratio = 2.33). 相似文献
89.
90.
Barjot C Hartigan-O'Connor D Salvatori G Scott JM Chamberlain JS 《The journal of gene medicine》2002,4(5):480-489