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601.
In the present work, we report the characterization of a Cryptosporidium parvum strain isolated from a patient who nearly drowned in the Deule River (Lille, France) after being discharged from the hospital where he had undergone allogeneic stem cell transplantation. After being rescued and readmitted to the hospital, he developed fulminant cryptosporidiosis. The strain isolated from the patient's stools was identified as C. parvum II2A15G2R1 (subtype linked to zoonotic exposure) and inoculated into SCID mice. In this host, this virulent C. parvum isolate induced not only severe infection but also invasive gastrointestinal and biliary adenocarcinoma. The observation of adenocarcinomas that progressed through all layers of the digestive tract to the subserosa and spread via blood vessels confirmed the invasive nature of the neoplastic process. These results indicate for the first time that a human-derived C. parvum isolate is able to induce digestive cancer. This study is of special interest considering the exposure of a large number of humans and animals to this waterborne protozoan, which is highly tumorigenic when inoculated in a rodent model.  相似文献   
602.

Background

Stand-alone nutritional set-ups are useful tools to grow plants at defined nutrient availabilities and to measure nutrient uptake rates continuously, in particular that for nitrate. Their use is essential when the measurements are meant to cover long time periods. These complex systems have, however, important drawbacks, including poor long-term reliability and low precision at high nitrate concentration. This explains why the information dealing with diel dynamics of nitrate uptake rate is scarce and concerns mainly young plants grown at low nitrate concentration.

Scope

The novel system detailed in this paper has been developed to allow versatile use in growth rooms, greenhouses or open fields at nitrate concentrations ranging from a few micro- to several millimoles per litres. The system controls, at set frequencies, the solution nitrate concentration, pH and volumes. Nitrate concentration is measured by spectral deconvolution of UV spectra. The main advantages of the set-up are its low maintenance (weekly basis), an ability to diagnose interference or erroneous analyses and high precision of nitrate concentration measurements (0·025 % at 3 mm). The paper details the precision of diurnal nitrate uptake rate measurements, which reveals sensitivity to solution volume at low nitrate concentration, whereas at high concentration, it is mostly sensitive to the precision of volume estimates.

Conclusions

This novel set-up allows us to measure and characterize the dynamics of plant nitrate nutrition at high temporal resolution (minutes to hours) over long-term experiments (up to 1 year). It is reliable and also offers a novel method to regulate up to seven N treatments by adjusting the daily uptake of test plants relative to controls, in variable environments such as open fields and glasshouses.  相似文献   
603.
A growing number of experimental and theoretical studies show the importance of partner choice as a mechanism to promote the evolution of cooperation, especially in humans. In this paper, we focus on the question of the precise quantitative level of cooperation that should evolve under this mechanism. When individuals compete to be chosen by others, their level of investment in cooperation evolves towards higher values, a process called competitive altruism, or runaway cooperation. Using a classic adaptive dynamics model, we first show that when the cost of changing partner is low, this runaway process can lead to a profitless escalation of cooperation. In the extreme, when partner choice is entirely frictionless, cooperation even increases up to a level where its cost entirely cancels out its benefit. That is, at evolutionary equilibrium, individuals gain the same payoff than if they had not cooperated at all. Second, importing models from matching theory in economics we, however, show that when individuals can plastically modulate their choosiness in function of their own cooperation level, partner choice stops being a runaway competition to outbid others and becomes a competition to form the most optimal partnerships. In this case, when the cost of changing partner tends towards zero, partner choice leads to the evolution of the socially optimum level of cooperation. This last result could explain the observation that human cooperation seems to be often constrained by considerations of social efficiency.  相似文献   
604.
This paper highlights the methods and parameters used to define and design a reference scenario to be compared with an industrial symbiosis (IS) scenario using the life cycle assessment (LCA) methodology. To this end, a critical review was conducted of 26 peer‐reviewed papers using LCA in the field of IS. The analysis focuses on the definition and design of reference scenarios through five cross‐analyses to determine correlations between the type and the number of reference scenarios and the type of IS scenarios studied and also some LCA characteristics such as the functional unit, the type of data used, and the use of sensitivity analysis. Results show that the definition of reference scenarios depends mainly on the type of IS scenario considered. For a current IS developed at an industrial scale, the suitable reference scenario is mainly a hypothetical nonsymbiotic reference scenario. For a prospective IS, the suitable reference scenario is mainly a current nonsymbiotic reference scenario. Due to this critical review, the problem of variability of reference scenarios emerges. To resolve it, the authors analyze different reference scenarios or use sensitivity analysis. What is more, territorial aspects are rarely taken into account in the design of reference scenarios. It is clearly a gap for LCA of IS because of the influence of territorial factors. The new research challenge is to include the consideration of territorial aspects to define and design the worst‐ and best‐case reference scenarios to assess strict environmental performances of IS.  相似文献   
605.
The purpose of this study was to examine age-related differences in the daily attention patterns of preschool, kindergarten, first-grade, and fifth-grade pupils by means of a cross-sectional sample of 4-11-year-old French students. The importance of this study comes from the need to understand attention and apply the information it provides in educational settings. The first study conducted in a school setting with three age groups (4-5-, 6-7-, and 10-11-year-olds) demonstrated a rapid rhythmicity (60 minute period) for preschoolers (4-5 years old), with higher performance at the beginning of a teaching session. This pattern evolved until the fifth grade (10-11-year-olds), after which the temporal variation in attention was comparable to that of working adults, with fluctuations occurring on a half-day basis. The children's scores on crossing-out tests rose during the morning, declined in the early afternoon, and then rose again later during the afternoon. The second study enhanced our understanding of the change of the rhythm in attention of 4-7-year-old pupils. The rapid daily rhythmicity, linked to a session effect, seems to gradually disappear as children move from preschool 2 to kindergarten (4-5- to 5-6-year-olds) and then on to first grade (6-7-year-olds), where the daily attention patterns are closer to the standard pattern found by chronopsychology studies. The evolving patterns obtained from group means were confirmed by analysis of individual patterns. Exploratory statistical analysis of the data provided greater detail on the observed interindividual patterns, indicating that within each school grade, the attention patterns of some children are similar to the standard pattern while the attention patterns of others are more atypical. Deviations were mainly found in the 5-6-year-old age range (kindergarteners). The greatest 'mixture' of patterns was observed in the kindergartners (5-6-year-olds). Age plays a role not only in modifying daily changes but also in the distribution of interindividual differences in daily fluctuations, which occur most when children are of kindergarten age (5-6 years of age).  相似文献   
606.
Twelve naturally occurring glucosinolates displaying alkenyl, hydroxylated, methylsulphinyl, aromatic and indole side chains were investigated by both negative and positive ion electrospray ionisation-tandem mass spectrometry (ESI-MS/MS). In order to resolve the MS/MS spectra obtained from the anion and cation molecular ions of glucosinolates, the different fragments were investigated by MSn experiments using an ion trap spectrometer. The MS3 spectra obtained permitted possible fragmentation schemes to be proposed. These were supported by accurate mass measurements of some characteristic diagnostic ions with the help of a quadrupole time-of-flight instrument. The negative ion ESI-MS/MS behaviour of the different glucosinolates investigated in this study confirmed previously described patterns and revealed new interesting structural informative fragments. Some are common to all the glucosinolates and others are highly specific for a type of variable side chain. The positive ion ESI-MS/MS fragments obtained from the [MNa+Na]+ or [MK+K]+ molecular ions did not provide complementary specific diagnostic ions. Nevertheless, when compared with the negative ion mode, the daughter ions appeared more homogenous and with a better relative abundance for all of the 12 compounds studied. Moreover, the positive ion mode appeared to be more efficient than the negative mode for the study of methoxylated glucosinolates and should be useful to detect the glucosinolates present as organic salts in crude plant extracts.  相似文献   
607.
Interleukin-9 is a cytokine with multiple functions, including the ability to activate group 2 innate lymphoid cells, which has been postulated to be therapeutically active in mouse models of arthritis. Similarly, interleukin-9 has been suggested to play an important role in tumor immunity. Here, we describe the cloning, expression, and characterization of three fusion proteins based on murine interleukin-9 and the F8 antibody, specific to the alternatively spliced EDA domain of fibronectin. EDA is strongly expressed in cancer and in various arthritic conditions, while being undetectable in the majority of healthy organs. Interleukin-9-based fusion proteins with an irrelevant antibody specific to hen egg lysozyme served as negative control in our study. The fusion proteins were characterized by quantitative biodistribution analysis in tumor-bearing mice using radioiodinated protein preparations. The highest tumor uptake and best tumor:organ ratios were observed for a format, in which the interleukin-9 moiety was flanked by two units of the F8 antibody in single-chain Fv format. Biological activity of interleukin-9 was retained when the payload was fused to antibodies. However, the targeted delivery of interleukin-9 to the disease site resulted in a modest anti-tumor activity in three different murine models of cancer (K1735M2, CT26, and F9), while no therapeutic benefit was observed in a collagen induced model of arthritis. Collectively, these results confirm the possibility to deliver interleukin-9 to the site of disease but cast doubts about the alleged therapeutic activity of this cytokine in cancer and arthritis, which has been postulated in previous publications.  相似文献   
608.
Spatial autocorrelation is a well‐recognized concern for observational data in general, and more specifically for spatial data in ecology. Generalized linear mixed models (GLMMs) with spatially autocorrelated random effects are a potential general framework for handling these spatial correlations. However, as the result of statistical and practical issues, such GLMMs have been fitted through the undocumented use of procedures based on penalized quasi‐likelihood approximations (PQL), and under restrictive models of spatial correlation. Alternatively, they are often neglected in favor of simpler but more questionable approaches. In this work we aim to provide practical and validated means of inference under spatial GLMMs, that overcome these limitations. For this purpose, a new software is developed to fit spatial GLMMs. We use it to assess the performance of likelihood ratio tests for fixed effects under spatial autocorrelation, based on Laplace or PQL approximations of the likelihood. Expectedly, the Laplace approximation performs generally slightly better, although a variant of PQL was better in the binary case. We show that a previous implementation of PQL methods in the R language, glmmPQL, is not appropriate for such applications. Finally, we illustrate the efficiency of a bootstrap procedure for correcting the small sample bias of the tests, which applies also to non‐spatial models.  相似文献   
609.
Heme oxygenase‐1 (HO‐1) encoded by the HMOX1 gene is a 32‐kDa stress protein that catabolizes heme to biliverdin, free iron, and carbon monoxide (CO). Glial HO‐1 is over‐expressed in the CNS of subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The HMOX1 gene is exquisitely sensitive to oxidative stress and is induced in brain and other tissues in various models of disease and trauma. Induction of the glial HMOX1 gene may lead to pathological brain iron deposition, intracellular oxidative damage, and bioenergetic failure in AD and other human CNS disorders such as PD and MS. Therefore, targeted suppression of glial HO‐1 hyperactivity may prove to be a rational and effective therapeutic intervention in AD and related neurodegenerative disorders. In this study, we report the effects of QC‐47, QC‐56, and OB‐28, novel azole‐based competitive and reversible inhibitors of HO‐1, on oxidative damage to whole‐cell and mitochondrial compartments in rat astrocytes transfected with the HMOX1 gene. We also report the effect of OB‐28 on the behavior and neuropathology of APPswe/PS1?E9 mice. OB‐28 was found to reduce oxidative damage to whole‐cell and mitochondrial compartments in rat astrocytes transfected with the HMOX1 gene. Moreover, OB‐28 was found to significantly counter behavioral deficits and neuropathological alterations in APPswe/PS1?E9 mice. Attenuation of AD‐associated behavioral deficits and neuropathological changes suggests that HO‐1 may be a promising target for neuroprotective intervention in AD and other neurodegenerative diseases.

  相似文献   

610.
The origins of and potential constraints on the evolution of phenotypic diversity remain one of the central questions in evolutionary biology. The vertebrate skeleton is governed by historical, developmental, architectural, and functional constraints that all play a role in establishing its final form. Whereas the factors underlying shape variation in single bones are fairly well understood, this is less so the case for complex assemblages of bones as observed in the cranium or mandible. It is often suggested that the final phenotype must reflect the mechanical constraints imposed by the loading of the skeleton as bones remodel to withstand loading. Yet, in the cranium, in contrast to the mandible, the final phenotype is likely constrained by demands other than loading including the protection of sensory systems and the brain. Architectural design constraints may further limit the final form of complex units like the vertebrate cranium. Here we use geometric morphometric approaches to quantify the shape of the cranium and mandible in a lizard and test whether the observed shape co-varies with both the muscles attaching to these structures as well as functional traits such as bite force. Our results show that co-variation between the cranium and mandible is significant and likely driven by the muscles that link the two systems. Moreover, our results show that the patterns of co-variation are stronger between the mandible and ventral side of the cranium. Muscular cross sectional areas, bite force, and the ventral side of the cranium, also co-vary more than the dorsal side of the cranium does with muscle properties and function. Finally, our results show sex-specific patterns of co-variation with males showing a stronger degree of integration between the cranium, mandible, muscles and bite force suggesting that constraints on bite force drive the evolution of cranial shape to a greater extent in males compared to females.  相似文献   
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