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Transfer Experiments (transfer + experiment)
Selected AbstractsConnectivities in molecules by INADEQUATE: recent developments,MAGNETIC RESONANCE IN CHEMISTRY, Issue 1 2002J. Buddrus Abstract The INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) consists of a pulse sequence which eliminates the NMR signals from isolated spins (spin system A) displaying signals from coupled spins (spin system AX or higher spin systems). It is of great importance when applied to molecules with skeleton elements such as carbon, silicon or tungsten, all of which contain a small percentage of spin-½ isotopes embedded in magnetically inactive isotopes. Analysis of the AX type spectra gives one-bond and long-range coupling constants (see compound 6) and, most important, the connectivity pattern of the skeleton atoms in molecules of unknown structure such as the carbon compounds 1 or 2, the silicon compound 3 or the lithium compound 4b. Unfortunately, INADEQUATE is rather insensitive, in the case of carbon only one out of 104 molecules gives the desired response. Efforts to reduce this drawback are described; recently, a remarkable step forward has been made by concentrating the four lines of an AX spin system to just two signals (see Fig. 2). Copyright © 2001 John Wiley & Sons, Ltd. [source] Hydrogen Atom Transfer Experiments Provide Chemical Evidence for the Conformational Differences between C - and O -DisaccharidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2010Elisa I. León Abstract The glycopyran-6- O -yl radical promoted hydrogen atom transfer reaction (HAT) between the two pyranose units of ,- D -Manp -(1,4)-,- D -Glcp and ,- D -Manp -(1,4a)-4a-carba-,- D -Glcp disaccharides provides supporting chemical evidence for the conformational differences between O - and C -glycosyl compounds. In the O -disaccharide the 6-alkoxyl radical, generated under oxidative or reductive conditions, abstracts exclusively the hydrogen at C-5, via a completely regioselective 1,8-HAT reaction. This may be attributable to the conformational restriction of the glycosidic and aglyconic bonds due principally to steric and stereoelectronic effects. On the contrary, very little regioselectivity is observed in the homologous C -disaccharide and a mixture of compounds generated by 1,5-, 1,6-, and 1,8-HAT processes where the abstraction occurs at hydrogen atoms positioned at C-4a, C-1,, and C-5,, respectively, has been obtained. This study has been extended to simpler O - and C -glycosides, where the aglycon was a straight n -alkyl alcohol tether of five atoms; in general, all of the results obtained are shown to be consistent with a major conformational flexibility of the C -glycosidic bond. [source] Heat transfer in high-aspect-ratio rectangular passage with skewed ribsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2002Takanari Okamura Abstract The heat transfer characteristics and flow behavior in a rectangular passage with two opposite 45° skewed ribs for turbine rotor blade have been investigated for Reynolds numbers from 7800 to 19,000. In this blade, the spanwise coolant passage at the trailing edge region whose thickness is very thin is chosen, so the channel aspect ratio (=width/height of channel) is extremely high, 4.76. Therefore the heat transfer experiment in the high-aspect-ratio cooling channel was performed using thermochromic liquid crystal and thermocouples. Furthermore, the calculation of flow and heat transfer was carried out using CFD analysis code to understand the heat transfer experimental results. The enhanced heat transfer coefficients on the smooth side wall at the rib's leading end were the same level as those on the rib-roughened walls. © 2002 Scripta Technica, Heat Trans Asian Res, 31(2): 89,104, 2002; DOI 10.1002/htj.10018 [source] Analysis of video images from a gas,liquid transfer experiment: a comparison of PCA and PARAFAC for multivariate image analysisJOURNAL OF CHEMOMETRICS, Issue 7 2003Stephen P. Gurden Abstract The use of chemical imaging is a developing area which has potential benefits for chemical systems where spatial distribution is important. Examples include processes in which homogeneity is critical, such as polymerizations, pharmaceutical powder blending and surface catalysis, and dynamic processes such as the study of diffusion rates or the transport of environmental pollutants. Whilst single images can be used to determine chemical distribution patterns at a given point in time, dynamic processes can be studied using a sequence of images measured at regular time intervals, i.e. a movie. Multivariate modeling of image data can help to provide insight into the important chemical factors present. However, many issues of how best to apply these models remain unclear, especially when the data arrays involved have four or five different dimensions (height, width, wavelength, time, experiment number, etc.). In this paper we describe the analysis of video images recorded during an experiment to investigate the uptake of CO2 across a free air,water interface. The use of PCA and PARAFAC for the analysis of both single images and movies is described and some differences and similarities are highlighted. Some other image transformation techniques, such as chemical mapping and histograms, are found to be useful both for pretreatment of the raw data and for dimensionality reduction of the data arrays prior to further modeling. Copyright © 2003 John Wiley & Sons, Ltd. [source] CAD,ICAD complex structure derived from saturation transfer experiment and simulated annealing without using pairwise NOE informationJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2004Tomoki Matsuda Abstract Saturation transfer experiments were performed for the 2H- and 15N-labeled mouse CAD domain of the caspase-activated deoxyribonuclease and the CAD domain of its inhibitor to reveal the protein,protein complexed conformation. Based on the physical model for the spin diffusion, a novel method was developed to reconstruct the complexed structure using the simulated annealing calculation. The complementarity in the molecular surface shape and the electrostatic potential distribution provide a good measure for the assessment of the putative complexed conformation, despite much less experimental information than the conventional distance geometry calculation. Copyright © 2004 John Wiley & Sons, Ltd. [source] 13C-detected IPAP-INADEQUATE for simultaneous measurement of one-bond and long-range scalar or residual dipolar coupling constantsMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2007Lan Jin Abstract The sensitivity of cryoprobes, which are rapidly becoming available, means that the measurement of coupling constants involving 13C, 13C pairs at the natural abundance of 13C can now, in principle, be done by using tens rather then hundreds of milligrams of compounds. However, a robust method that would yield reliable values of small long-range carbon--carbon coupling constants is still missing. In this Communication, we describe a novel 13C,detected incredible natural-abundance double-quantum transfer experiment (INADEQUATE) experiment for simultaneous correlation of one-bond and long-range 13C13C pairs and the measurement of both types of coupling constants in 13C natural abundance samples. This method yields accurate values of one-bond and long-range coupling constants by manipulation of pure phase in-phase (IP) and antiphase (AP) doublets, and is referred to as 13C-detected IPAP-INADEQUATE. It is illustrated by the measurement of interglycosidic 3JCCOC coupling constants in a disaccharide molecule providing important information about the conformation of the glycosidic linkage. Owing to the simplicity of INADEQUATE spectra the carbon,carbon coupling constants are particularly suitable for studies of partially oriented molecules through the measurement of carbon,carbon residual dipolar couplings (RDCs). An example of this approach is presented. We expect the method to find a variety of applications in the conformational analysis of small molecules, determination of diastereoisomers and enantiomers, and studies of molecules in aligned media. Copyright © 2007 John Wiley & Sons, Ltd. [source] 3D Heteronuclear long-range 1H,13C scalar correlation at natural abundance: application to oligosaccharide analysisMAGNETIC RESONANCE IN CHEMISTRY, Issue 3 2002Griselda Hernández Abstract A 3D 1H,13C,1H refocused INEPT transfer experiment is proposed in which the initial coherence transfer of 1H longitudinal to 13C transverse magnetization is tuned to the long-range 1H, 13C couplings while the reverse INEPT component transfers the magnetization to the directly bonded 1H. Integration of a constant time 1H evolution period into the long-range coherence transfer interval provides absorption mode signals for each dimension. A 13C purge component at the beginning of the sequence selects for 12C-bound 1H magnetization that is then transferred to a 13C-bound hydrogen, thus strongly suppressing the diagonal signals. This experiment is expected to be of particular value for situations in which resonance overlap in the 13C dimension renders 2D long-range heteronuclear correlation data ambiguous. In combination with a diagonal-suppressed 3D 1H,13C,1H TOCSY-HSQC experiment, complete assignment of the ring resonances of the Lewis-b hexasaccharide was obtained on a 4.2 mM sample using a conventional 500 MHz probe (0.1% ethylbenzene signal-to-noise ratio of 600), suggesting its applicability to sub-millimolar samples using cryoprobe technology. Copyright © 2002 John Wiley & Sons, Ltd. [source] Quantitative ATP synthesis in human liver measured by localized 31P spectroscopy using the magnetization transfer experimentNMR IN BIOMEDICINE, Issue 5 2008A. I. Schmid Abstract The liver plays a central role in intermediate metabolism. Accumulation of liver fat (steatosis) predisposes to various liver diseases. Steatosis and abnormal muscle energy metabolism are found in insulin-resistant and type-2 diabetic states. To examine hepatic energy metabolism, we measured hepatocellular lipid content, using proton MRS, and rates of hepatic ATP synthesis in vivo, using the 31P magnetization transfer experiment. A suitable localization scheme was developed and applied to the measurements of longitudinal relaxation times (T1) in six healthy volunteers and the ATP-synthesis experiment in nine healthy volunteers. Liver 31P spectra were modelled and quantified successfully using a time domain fit and the AMARES (advanced method for accurate, robust and efficient spectral fitting of MRS data with use of prior knowledge) algorithm describing the essential components of the dataset. The measured T1 relaxation times are comparable to values reported previously at lower field strengths. All nine subjects in whom saturation transfer was measured had low hepatocellular lipid content (1.5,±,0.2% MR signal; mean,±,SEM). The exchange rate constant (k) obtained was 0.30,±,0.02,s,1, and the rate of ATP synthesis was 29.5,±,1.8,mM/min. The measured rate of ATP synthesis is about three times higher than in human skeletal muscle and human visual cortex, but only about half of that measured in perfused rat liver. In conclusion, 31P MRS at 3,T provides sufficient sensitivity to detect magnetization transfer effects and can therefore be used to assess ATP synthesis in human liver. Copyright © 2007 John Wiley & Sons, Ltd. [source] Activating and inhibitory Fc, receptors can differentially modulate T cell-mediated autoimmunityEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2008Mirentxu Abstract The molecular bases responsible for the loss of T cell tolerance to myelin antigens leading to the onset of multiple sclerosis remain obscure. It has been shown that balanced signaling through activating and inhibitory receptors is critical for the maintenance of tolerance to self antigens in autoimmune disorders. However, although Fc,R have been shown to influence experimental autoimmune encephalomyelitis (EAE) development, their role during pathogenesis remains controversial. Here we have evaluated whether relative expression of activating (Fc,RIII) and inhibitory (Fc,RIIb) Fc,R can modulate myelin-specific T cell response, as well as the susceptibility to develop EAE in mice. While Fc,RIIb,/, mice showed a significant increase in EAE severity, an Fc,RIII deficiency protected mice from disease. In addition, Fc,RIIb,/, mice showed enhanced activation of myelin-specific effector T cells, which were significantly more effective at causing EAE in adoptive transfer experiments than were T cells from wild-type mice. In contrast, Fc,RIII,/, mice showed a significantly reduced activation of myelin-specific T cells and these cells failed to adoptively transfer EAE. Consistently, increased expansion of regulatory T cells (Treg) during EAE was observed only for Fc,RIII,/, mice, which were able to suppress disease when adoptively transferred to recipient mice. These findings suggest that the balance between activating and inhibitory Fc,R signaling can contribute to the maintenance of T cell tolerance to myelin antigens and modulate EAE progression. [source] Therapy-induced antitumor vaccination by targeting tumor necrosis factor-, to tumor vessels in combination with melphalanEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2007Lorenzo Mortara Abstract Treatment of tumor-bearing mice with mouse (m)TNF-,, targeted to tumor vasculature by the anti-ED-B fibronectin domain antibody L19(scFv) and combined with melphalan, induces a therapeutic immune response. Upon treatment, a highly efficient priming of CD4+ T cells and consequent activation and maturation of CD8+ CTL effectors is generated, as demonstrated by in vivo depletion and adoptive cell transfer experiments. Immunohistochemical analysis of the tumor tissue demonstrated massive infiltration of CD4+ and CD8+ T cells 6,days after treatment and much earlier in the anamnestic response to tumor challenge in cured mice. In fact, the curative treatment with L19mTNF-, and melphalan resulted in long-lasting antitumor immune memory, accompanied by a mixed Th1/Th2-type response and significant in vitro tumor-specific cytolytic activity. Finally, the combined treatment reduced the percentage and absolute number of CD4+CD25+ regulatory T cells in the tumor-draining lymph nodes of mice responding to therapy, and this was associated with the establishment of protective immunity. These findings pave the way for alternative therapeutic strategies based on the targeted delivery of biological and pharmacological cytotoxic compounds that not only kill most of the tumor cells but, more importantly, trigger an effective and long-lasting antitumor adaptive immune response. [source] Lipid-induced conformational transition of the amyloid core fragment A,(28,35) and its A30G and A30I mutantsFEBS JOURNAL, Issue 10 2008Sureshbabu Nagarajan The interaction of the ,-amyloid peptide (A,) with neuronal membranes could play a key role in the pathogenesis of Alzheimer's disease. Recent studies have focused on the interactions of A, oligomers to explain the neuronal toxicity accompanying Alzheimer's disease. In our study, we have investigated the role of lipid interactions with soluble A,(28,35) (wild-type) and its mutants A30G and A30I in their aggregation and conformational preferences. CD and Trp fluorescence spectroscopic studies indicated that, immediately on dissolution, these peptides adopted a random coil structure. Upon addition of negatively charged 1,2-dipalmitoyl- syn -glycero-3-phospho- rac -(glycerol) sodium salt (PG) lipid, the wild-type and A30I mutant underwent reorganization into a predominant ,-sheet structure. However, no conformational changes were observed in the A30G mutant on interaction with PG. In contrast, the presence of zwitterionic 1,2-dipalmitoyl- syn -glycero-3-phosphatidylcholine (PC) lipid had no effect on the conformation of these three peptides. These observations were also confirmed with atomic force microscopy and the thioflavin-T assay. In the presence of PG vesicles, both the wild-type and A30I mutant formed fibrillar structures within 2 days of incubation in NaCl/Pi, but not in their absence. Again, no oligomerization was observed with PC vesicles. The Trp studies also revealed that both ends of the three peptides are not buried deep in the vesicle membrane. Furthermore, fluorescence spectroscopy using the environment-sensitive probe 1,6-diphenyl-1,3,5-hexatriene showed an increase in the membrane fluidity upon exposure of the vesicles to the peptides. The latter effect may result from the lipid head group interactions with the peptides. Fluorescence resonance energy transfer experiments revealed that these peptides undergo a random coil-to-sheet conversion in solution on aging and that this process is accelerated by negatively charged lipid vesicles. These results indicate that aggregation depends on hydrophobicity and propensity to form ,-sheets of the amyloid peptide, and thus offer new insights into the mechanism of amyloid neurodegenerative disease. [source] Why there is better evidence for culture in fish than chimpanzeesJOURNAL OF FISH BIOLOGY, Issue 2003K. N. Laland Fish have comparatively small brains and are not renowned for their intelligence. Yet a series of laboratory experiments on the guppy reveals that they can be surprisingly good at learning from each other, and that social learning processes can mediate behavioural traditions analogous to the tool using traditions of different populations of chimpanzees. Transmission chain experiments have established that arbitrary and even maladaptive information can be socially transmitted among shoals of fish. Studies of behavioural innovation in guppies are strikingly consistent with findings of equivalent studies in primates. There are strong sex differences in innovatory tendencies and social learning abilities in guppies, which also parallel observations of primates. These studies suggest that the adage ,necessity is the mother of invention' may be a characteristic feature of animal innovation. When considered in combination with the findings of transfer experiments carried out on natural populations of fish, it becomes apparent that fish are an excellent model system for studies of animal social learning and culture. [source] CAD,ICAD complex structure derived from saturation transfer experiment and simulated annealing without using pairwise NOE informationJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2004Tomoki Matsuda Abstract Saturation transfer experiments were performed for the 2H- and 15N-labeled mouse CAD domain of the caspase-activated deoxyribonuclease and the CAD domain of its inhibitor to reveal the protein,protein complexed conformation. Based on the physical model for the spin diffusion, a novel method was developed to reconstruct the complexed structure using the simulated annealing calculation. The complementarity in the molecular surface shape and the electrostatic potential distribution provide a good measure for the assessment of the putative complexed conformation, despite much less experimental information than the conventional distance geometry calculation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Saturation transfer and chemical exchange measurements of the stereochemical drift occurring during the Wittig reactionMAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2005Aurelia Pascariu Abstract The Wittig reaction of butylidenetriphenylphosphorane with benzaldehyde using LiHMDS as base in THF was studied. The stereochemical drift (different ratio obtained in alkenes versus oxaphosphetane intermediates) was followed by low-temperature 1D NMR techniques. A retro-Wittig reaction is demonstrated using 13C and 31P saturation transfer experiments and homonuclear DPFGSE-ROE techniques. Copyright © 2005 John Wiley & Sons, Ltd. [source] Aberrant distribution of junctional complex components in retinoic acid receptor alpha-deficient miceMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2010Sanny S.W. Chung Abstract Retinoic acid receptor alpha (RAR,)-deficient mice are sterile, with abnormalities in the progression of spermatogenesis and spermiogenesis. In this study, we investigated whether defective retinoid signaling involved at least in part, disrupted cell,cell interactions. Hypertonic fixation approaches revealed defects in the integrity of the Sertoli-cell barrier in the tubules of RAR,-deficient testes. Dye transfer experiments further revealed that coupling between cells from the basal to adluminal compartments was aberrant. There were also differences in the expression of several known retinoic acid (RA)-responsive genes encoding structural components of tight junctions and gap junctions. Immunostaining demonstrated a delay in the incorporation of zonula occludens (ZO-1), a peripheral component protein of tight junctions, into the Sertoli cell tight junctions. Markedly reduced expression of connexin-40 in mutant pachytene spermatocytes and round spermatids was found by in situ hybridization. An ectopic distribution of vimentin and disrupted cyclic expression of vimentin, which is usually tightly regulated during spermiogenesis, was found in RAR,-deficient testes at all ages examined. Thus, the specific defects in spermiogenesis in RAR,-deficient testes may correlate with a disrupted cyclic expression of RA-responsive structural components, including vimentin, a downregulation of connexin-40 in spermatogenic cells, and delayed assembly of ZO-1 into Sertoli cell tight junctions. Interestingly, bioinformatic analysis revealed that many genes that are components of tight junctions and gap junctions contained potential retinoic acid response element binding sites. Microsc. Res. Tech., 2010. © 2009 Wiley-Liss, Inc. [source] Molecular engineering of resveratrol in plantsPLANT BIOTECHNOLOGY JOURNAL, Issue 1 2009Bertrand Delaunois Summary The grapevine phytoalexin resveratrol, the synthesis of which is achieved by stilbene synthase (STS), displays a wide range of biological effects. Most interest has centred, in recent years, on STS gene transfer experiments from grapevine to the genome of numerous plants. This work presents a comprehensive review on plant molecular engineering with the STS gene. Gene and promoter options are discussed, namely the different promoters used to drive the transgene, as well as the enhancer elements and/or heterologous promoters used to improve transcriptional activity in the transformed lines. Factors modifying transgene expression and epigenetic modifications, for instance transgene copy number, are also presented. Resveratrol synthesis in plants, together with that of its glucoside as a result of STS expression, is described, as is the incidence of these compounds on plant metabolism and development. The ectopic production of resveratrol can lead to broad-spectrum resistance against fungi in transgenic lines, and to the enhancement of the antioxidant activities of several fruits, highlighting the potential role of this compound in health promotion and plant disease control. [source] A Study on Hydrodynamics and Heat Transfer in a Bubble Column Reactor with Yeast and Bacterial Cell SuspensionsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2005Nigar Kantarci Abstract Hydrodynamics and heat transfer experiments were carried out in a slurry bubble column with air-water-yeast cells and air-water-bacteria cells systems to investigate gas hold-up, bubble characteristics and heat transfer coefficients with cell concentrations of 0.1% w/w and 0.4% w/w and superficial gas velocity up to 0.20 m/s. The gas hold-ups and heat transfer coefficients were found to increase with increasing gas velocity and cell concentration. The heat transfer coefficients were higher at the centre of the column as compared to the near wall region. The development of empirical correlations to predict the heat transfer coefficient in two- and three-phase systems was carried out with ±15% confidence interval at most. On a réalisé des expériences d'hydrodynamique et de transfert de chaleur dans une colonne triphasique gaz-liquide-solide avec des systèmes de cellules air-eau-levure et de cellules air-eau-bactéries afin d'étudier la rétention de gaz, les caractéristiques des bulles et les coefficients de transfert de chaleur avec des concentrations de cellules de 0,1 % en poids et 0,4 % en poids et des vitesses de gaz superficielles jusqu'à 0,20 m/s. On a trouvé que les rétentions de gaz et les coefficients de transfert de chaleur augmentaient avec la vitesse de gaz et la concentration en cellules. Les coefficients de transfert de chaleur sont plus grands au centre de la colonne que dans la région proche de la paroi. Des corrélations empiriques pour prédire le coefficient de transfert de chaleur dans des systèmes bi et triphasiques ont été établies avec un écart de confiance inférieur ou égal à ± 15%. [source] REVIEW ARTICLE: Maternal Transmission of Asthma RiskAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2009Robert H. Lim Maternal asthma significantly increases the risk of asthma in offspring, but the mechanisms remain poorly defined. We review animal models used to study the maternal effect, focusing on a murine model developed in our laboratory. Mother mice rendered allergic to ovalbumin produce offspring that are more susceptible to allergic sensitization, seen as airway hyperresponsiveness and allergic airway inflammation after a sensitization protocol, which has minimal effects on newborns from normal mothers. Mechanistic analyses identify a role for interleukin-4 (based on pre-mating injection of neutralizing antibodies), dendritic cells and allergen-specific T cells (based on adoptive transfer experiments). Other maternal exposures (e.g. pollutant exposure and non-pulmonary allergy) can increase asthma susceptibility in offspring. This observation implies that the maternal transmission of asthma represents a final common pathway to various types of inflammatory stimuli. Identification of the shared molecular mechanisms in these models may allow better prevention and therapy. Current knowledge, gaps in knowledge and future directions are discussed. [source] CTLA-4 (CD152) controls homeostasis and suppressive capacity of regulatory T cells in miceARTHRITIS & RHEUMATISM, Issue 1 2009Paula Kolar Objective CD4+CD25+ regulatory T cells (known as Treg cells) suppress unwanted and autoreactive T cell responses. Treg cells express the costimulatory molecule CTLA-4 intracellularly, but the mechanisms by which Treg cells exploit CTLA-4 signaling remain unclear. The present study was undertaken to investigate the role of CTLA-4 in controlling the homeostasis and suppressive function of Treg cells. Methods Murine Treg cells were analyzed by flow cytometry for coexpression of CTLA-4 and typical Treg cell,expressed molecules, and the influence of CTLA-4 on T cell proliferation, suppression, and apoptosis was investigated by in vitro assays. To analyze the importance of CTLA-4 in Treg cell,mediated suppression in vivo, wild-type Treg cells were transferred into CTLA-4,deficient mice displaying lymphoproliferation, and survival was monitored over time. Results A strong correlation between expression of forkhead box P3 and ex vivo expression of CTLA-4 in Treg cells was observed. Inhibition of CTLA-4 signaling in Treg cells during in vitro stimulation increased cell cycling and led to enhanced activation-induced cell death (AICD), which was mediated by CD95/CD95 ligand,induced activation of caspases. Blockade of CTLA-4 signaling resulted in impairment of the suppressive capacity of Treg cells. Despite these effects, high amounts of Treg cells persisted in CTLA-4,deficient mice. Results of transfer experiments in CTLA-4,deficient mice showed that the mice had a significantly prolonged lifespan when CTLA-4,competent Treg cells were injected. Conclusion Expression of CTLA-4 on Treg cells serves to control T cell proliferation, to confer resistance against AICD, and to maintain the suppressive function of Treg cells. [source] Suppressive role of leukocyte cell,derived chemotaxin 2 in mouse anti,type II collagen antibody,induced arthritisARTHRITIS & RHEUMATISM, Issue 2 2008Akinori Okumura Objective We previously reported that the Val58Ile polymorphism of the leukocyte cell,derived chemotaxin 2 gene (LECT2) is associated with the severity of rheumatoid arthritis (RA). To define the role of LECT2 in inflammatory arthritides, we investigated the development of collagen antibody,induced arthritis (CAIA) in LECT2-deficient (LECT2,/,) mice. Methods CAIA was induced in mice by administering anti,type II collagen antibodies followed by lipopolysaccharide. Daily assessment of hind paw swelling was used to monitor the development of arthritis. The histopathologic features and expression of inflammatory cytokines were also analyzed. We confirmed the role of LECT2 by introducing a LECT2 expression vector into LECT2,/, mice, using a hydrodynamic gene transfer method. Results Arthritis in LECT2,/, mice was significantly exacerbated compared with that in wild-type (WT) controls. Histopathologic assessment of the tarsal joints showed that inflammation and erosion of cartilage and bone in LECT2,/, mice were more severe than that in controls. Interleukin-1, (IL-1,), IL-6, and certain chemokines were present at significantly higher levels in the arthritic hind paws of LECT2,/, mice. In contrast, the amount of LECT2 in the serum and locally in the hind paws was higher in arthritic WT mice. Finally, hydrodynamic gene transfer experiments revealed that the severity of arthritis was reduced by the systemic expression of exogenous mouse LECT2 protein in LECT2,/, mice. Conclusion These results strongly suggest that LECT2 directly suppresses the development of CAIA. Manipulation of LECT2 might provide a rationale for novel therapeutic approaches to the treatment of inflammatory arthritides such as RA. [source] Fast Batch to Continuous Transposition: Application to the Extraction of Andrographolide from PlantsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2006L. Prat Abstract A fast development method for batch to continuous process transposition is proposed. This method is based on transient regime experiment analyses and is applied to a solid-liquid extraction. The application under consideration is the extraction of an active principle from a plant in a non-sinusoidal pulsed column. Typically, the proposed signal is composed of two different periods: firstly, a classical sinusoidal pulsation step is used to mix the liquid and solid phases in the active part of the column and allow an optimal mass transfer and, secondly, an impulsion phase, used generally for the transport of solids. The extraction is carried out in a disc and doughnut column of 54,mm diameter and 3.5,m height. Liquid and solid are flowing co-currently and downwardly. This technological improvement has been implemented to solve the difficulties due to the significant heterogeneity of the matter: one part tends to float and other to sink, which always leads to a definitive flooding in classical operations. The effects of the solid flow rate and the solvent characteristics on the hydrodynamic behavior of the column are studied. The mean residence time and the total solid holdup are calculated by using a transient regime mass balance on the experimental results. These experiments allow the identification and quantification of opposite effects of the operating parameters. Mass transfer experiments have been performed and the results fit calculated values obtained by coupling the hydrodynamic and batch extraction results. Despite the simplifications made, this validates the fast development method proposed to help batch to continuous transposition. [source] Synthesis, Characterization, and Application of Cationic Water-Soluble Oligofluorenes in DNA-Hybridization DetectionCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2008Bin Liu Prof. Abstract A simple and efficient approach was developed for the synthesis of a series of cationic water-soluble oligofluorenes up to a chain length of a heptamer. Bromoalkyl-substituted fluorenyl boronic esters as the key intermediates were synthesized by using a modified Miyaura reaction. With an increasing number of repeat units (trimer to hexamer), the size-specific oligomers have shown redshifts in both the absorption and emission maxima. The emission maximum reaches the limit for the hexamer in both water and buffer solution. The quantum yields of the oligomers decreased with increased oligomer size in water. Both fluorescence quenching of the oligomers by 9,10-anthraquinone-2,6-disulfonate and the fluorescence resonance energy transfer experiments with the oligomers as the donor and fluorescein (Fl)-labeled double-stranded DNA (dsDNA-Fl) as the acceptor revealed the chain-length-dependent behavior. The Stern,Volmer quenching constant increased with the molecular size, whereas the highest donor-sensitized Fl emission was observed for the hexamer. These size-specific oligomers also served as a model to study the structure,property relationships for cationic polyfluorenes. [source] ,, T cells assist ,, T cells in the adoptive transfer of contact hypersensitivity to para-phenylenediamineCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2001H. Yokozeki Para-phenylenediamine (PPD) is known to be a common sensitizer of allergic contact dermatitis and contact urticaria. To clarify the mechanism of contact hypersensitivity (CHS) to PPD, we established a mouse model of PPD-induced CHS. BALB/c mice were immunized for 3 consecutive days by painting topically a 2·5% PPD solution on their shaved abdominal skin. On days 5, 7 or 9 after the initial application, the mice were challenged by applications of a 2·5% PPD solution. Maximal ear swelling was determined at 24 h but another statistically significant and smaller ear swelling was observed 1 h after challenge with PPD in a hapten-specific manner. Adoptive cell transfer experiments demonstrated that the ear swelling of the adoptive cell transferred mice displayed an early response at 6 h and a late response from 12 h to 24 h when the recipient mice were challenged immediately after transfer. Both MoAbs and complement treatment of the transferred cells demonstrated that the phenotype of the early response cells which elicited a response at 6 h after challenge was Thy1+, B220+, ,, TCR, ,, TCR, CD3, CD4, CD5+ and CD8. The in vitro treatment of effector cells with MoAbs against not only ,, TCR but also ,, TCR, together with complement, was found to diminish substantially the late response, elicited 12,24 h after challenge. ,, T cells reconstituted the ability of ,, T cells to transfer 24 h CHS responsiveness. The phenotype of the ,, T cells that assist CHS effector ,, T cells was CD3+, CD4 and CD8+ and these regulatory ,, T cells were neither Ag-specific nor MHC-restricted. Furthermore, ,, T cells from normal spleen could also assist ,, T cells in adoptive transfer of the 24 h CHS response in a non-MHC-restricted manner. RT-PCR demonstrated that ,, T cells strongly expressed mRNA IFN- ,, whereas ,, T cells expressed not only IFN- , but also IL-4 and IL-10. These data indicate that not only early response cells and ,, T cells but also Th2 type ,, T cells may play an important role in the elicitation of CHS to PPD. [source] | ||||||||||||||||