bluuebunny/crossref_metadata_2025_split huggingface dataset:
The dynamic state of the macrophage plasma membrane. Attachment and fate of immunoglobulin, antigen and lectins
Authors: Loor F. , Roelants G. E. 
Published: February 2007

AbstractThe dynamic state of the macrophage plasma membrane and its possible role in antigen presentation were studied by fluorescence microscopy. Our main observations are as follows: (a) macrophages from the peritoneal cavity of mice have easily detectable surface Ig which, in small/medium macrophages, remains associated with the membrane for four days in culture. On larger macrophages it is progressively lost by capping. Most of this surface Ig is rapidly redistributed in polar caps by divalent but not monovalent anti‐Ig reagents. Complete clearance of the membrane is, however, difficult to obtain. (b) Binding and redistribution of concanavalin, phytohemagglutinin and poly‐L‐lysine on macrophages are as described for lymphocytes. However, pokeweed mitogen, which binds in a detectable way only to thymocytes and not to peripheral B or T lymphocytes, binds also to macrophages and redistributes in polar caps by itself. (c) Antigen binds well to macrophages at 37 °C and weakly at 0 °C, but binding is not sensitive to NaN3. Macrophages do not show selectivity for antigen binding. Part of the bound antigen is redistributed in caps and endocytozed, but some antigen is still detected at the cell surface after 4 days of culture. Antigen binding is not antibody mediated. Antigen appears to stick to a ubiquitous macrophage membrane component and not to a receptor. Part of the endocytozed antigen is later reexposed at the plasma membrane surface.These findings extend the fluid mosaic model to the macrophage membrane and reconcile high endocytic activity and membrane fluidity with the antigen presentation role of macrophages.
T cell suppression in vitro. II. Nature of specific suppressive factor
Authors: Feldmann Marc 
Published: February 2007

AbstractThe mechanism of specific T cell suppression in vitro was investigated. It was found that suppression of hapten‐reactive B cells only occurred in the presence of hapten linked to the carrier to which the T cells were reacting. Thus, there was the same requirement for linked recognition in T cell suppression as was previously described in cooperation. The nature of the suppressive factor was investigated, and like the cooperating factor, it was found to have specificity for the immunizing carrier protein and to be fully absorbed by peritoneal macrophages. The ratio of helper to suppressor activity obtained from activated T cells did not change between 4 and 8 days after injection of antigen and thymocytes. Both activities were absorbed by Sepharose beads conjugated with polyvalent anti‐mouse Ig, anti‐ϰ or anti‐μ‐chain antibody. There was thus a resemblance between the T cell suppressive factor and the immunizing factor, although it is not yet known whether both properties are expressed by one and the same molecule. This must await further biochemical characterization of specific T cell factors.
The preparation and purification of HL‐A monospecific antigens using platelets and various lymphoid sources
Authors: Voigtmann R. , Uhlenbruck G. , Pardoe G. I. , Rogers K. 
Published: February 2007

AbstractHL‐A‐active protein fragments have been isolated from lymphoid sources (tonsillar tissue, cells from lymphoblastoid cell lines (LCL cells)) and from platelets. The yields and specific activities of products obtained by enzymic chaotropic treatment indicate the superiority of 3 M KCl extraction of platelets. Individual HL‐A antigenic specificities were further distinguished in fractions separated by polyacrylamide gel electrophoresis. Antigens were separated between the LA and FOUR loci, and within the LA locus. Purified monospecific HL‐A antigenic preparations were conjugated with aminoethyl‐Sepharose‐4B, and used to remove corresponding specificities from alloantisera.
Enhancing T lymphocytes from tumor‐bearing mice suppress host resistance to a syngeneic tumor
Authors: Treves A. J. , Carnaud C. , Trainin N. , Feldman M. , Cohen I. R. 
Published: February 2007

AbstractThe cell‐mediated immune response of animals to a lethal syngeneic tumor was investigated by inoculating C57BL mice with Lewis lung carcinoma (3LL) cells T lymphocytes, obtained from the enlarged spleens of the tumor‐bearing mice were found to be cytotoxic to 3LL target cells in vitro. However, we found that such spleen cells enhanced tumor growth in vivo when mice were injected with a mixture of spleen cells and tumor cells. Removal of T lymphocytes by treatment of the spleen cells with anti‐Θ serum plus complement reduced the enhancement of tumor growth. Hence, the tumor enhancing cells, like the cytotoxic cells, appeared to be T lymphocytes. Removal of T lymphocytes from normal mice by adult thymectomy before tumor inoculation led to a reduction in the number of tumor metastases. Thus, enhancing T lymphocytes appear to exist in normal as well as in tumor‐bearing mice. Investigation of this mechanism of tumor enhancement suggested that the enhancing T lymphocytes act as suppressor T cells inhibiting natural immune resistance to tumor growth.
Antibody‐induced changes in expression of the H‐2 antigen
Authors: Lesley Jayne , Hyman R. 
Published: February 2007

AbstractContinuous exposure of a BALB/c myeloma line to anti‐H‐2d antibody in the absence of complement, for 3 hours at 37 °C, results in the loss of sensitivity to lysis by added complement or by added anti‐H‐2d and complement (antigenic modulation). 125I‐labeled anti‐H‐2d was used to follow the fate of the modulating antibody. Iodinated rabbit anti‐mouse Ig was used to detect anti‐H‐2 Ig remaining on the cell surface at various times. It was found that the amount of anti‐H‐2 antibody detectable on the cell surface decreases by 1/3 to 1/2, and that this decrease occurs by internalization of the bound antibody (and presumably of the antigen). Maintenance of antigenic modulation over a 24‐hour period involves a steady state of continuous binding of free antibody and its internalization.Recovery from antigenic modulation occurs during 3 hours after removal of the anti‐H‐2 antibody and involves a decrease in the amount of mouse anti‐H‐2d remaining on the cell surface (as detected by labeled rabbit anti‐mouse Ig) and an increase in the amount of surface antigen detected by the ability to bind 125I‐labeled anti‐H‐2d.
An anti‐theta sensitive hapten‐carrier response in nude mice
Authors: Kirov Sylvia Mary 
Published: February 2007

AbstractSpleen cells from congenitally athymic (“nude”) mice were found to give a good anti‐hapten response when cultured with the hapten‐carrier, dinitrophenyl (DNP)‐flagellin, but not when cultured with DNP coupled to two other proteins, hemocyanin and human IgG. This response to DNP‐flagellin was anti‐theta‐sensitive. The evidence indicated that the mice had a small population of T cells, a proportion of which had become primed naturally to flagellin or to related antigens and could function as specific helper cells in a collaborative anti‐DNP response. The existence of such flagellin‐primed T cells was confirmed by the ability of such mice to mount a delayed type hypersensitivity reaction to flagellin injected into the hind footpad.
The generation of antibody diversity. II. Plaque morphology as a simple marker for antibody specificity at the single‐cell level
Authors: Cunningham A. J. , Pilarski Linda M. 
Published: February 2007

AbstractThis paper investigates the validity of plaque morphology as a simple marker for distinguishing single cells producing antibody with different specificities. Plaques on an indicator mixture of related erythrocytes may be clear, with both red cell types lysed, or partial with only one lysed, or “sombreros” where both target erythrocytes are lysed but to different extents. The technique can be adapted for use with defined antigens by testing cells against indicator erythrocytes half of which are coupled at high density with the antigen and half at low density: again the population is split into clear and partial plaques. Various arguments and control experiments have been put forward to support the claim that plaque morphology depends on antibody specificity, and hence V region structure, and not on amount of antibody or C region changes: morphology remains the same at different temperatures of incubation, and as a plaque grows at 37 °C, and is not affected by different concentrations of complement in the medium.
Tolerance induction to a hapten protein conjugate in vivo: Are suppressor T cells involved
Authors: Huchet R. , Feldmann Marc 
Published: February 2007

AbstractThe cellular basis of high and low zone tolerance to dinitrophenylated human IgG (DNP‐HGG) was investigated in mice by using an analysis of carrier hapten relationships to identify the nonresponding cell. Low zone tolerance in vivo was found to be solely due to tolerance at the T cell level, confirming the previous work of Mitchison and Rajewsky. High zone tolerance, after a single injection of 10 mg of deaggregated DNP‐HGG was due to essentially complete T cell tolerance. It was also due to partial B cell tolerance in the intact host. The degree of B cell tolerance was much more marked if tested in vitro than in vivo, and for IgG antibody rather than IgM. The mechanism of high zone tolerance induction was analyzed. Two and three days after antigen injection there was a transient appearance of T cells which, in the presence of the tolerogen, specifically suppressed DNP‐reactive B cells in vitro. The significance of these specific suppressor T cells in the mechanism of induction of high zone tolerance is discussed.
A one‐step procedure for separating mouse T and B lymphocytes
Authors: Parish C. R. , Kirov Sylvia M. , Bowern Narelle , Blanden R. V. 
Published: February 2007

AbstractA procedure is described for both depleting and obtaining in pure form Ig‐bearing cells from mouse lymphoid populations. The Ig‐bearing cells are identified by rosetting and the rosettes separated from the nonrosetting lymphocytes by centrifugation on Isopaque/Ficoll. The rosettes sink with the red cells and the nonrosetting lymphocytes float. The procedure is > 99.5 % efficient at depleting mouse lymphoid populations of Ig‐rosetting cells and is also > 97 % efficient at removing the Ig‐bearing cells detected by radioautography. Furthermore, after lysis of the red cells by hypotonic shock the Ig‐bearing cells are recovered in a highly pure form. The total recovery of white cells and rosettes applied is > 85 %.This procedure was shown to produce a functional separation of T and B lymphocytes. The cell population depleted of Ig‐rosettes behaved as a pure T cell preparation. It lacked precursors of antibody‐forming cells, but contained virtually all of the Θ‐positive lymphocytes, the bulk of the helper cells detected in two in vitro hapten carrier antibody responses and all the cells which responded and produced cytotoxic cells in MLC. In contrast, the preparation of Ig rosettes expressed B cell properties. This population contained all of the antibody forming cell precursors, few helper cells and Θ‐positive lymphocytes and no MLC‐responding cells. However, there was some evidence that a small subpopulation of T cells exists which possesses surface Ig.The separation system was used to formally demonstrate that carrier primed T cells collaborate with hapten primed B cells to generate an anti‐hapten antibody response to a hapten‐carrier conjugate. It was also established that in MLC responder B cells in no way collaborate with responder T cells to generate cytotoxic cells.
Analysis of antibody populations to oligo‐D‐alanine determinants. V. A method for measuring hapten inhibition by decreased initial rate of red cell sensitization
Authors: Trissl Dorothea , Weiler E. 
Published: February 2007

AbstractA method is described to analyze separately the affinity of allotypic or subclass antibody subpopulations of anti‐poly‐D‐ala antisera. The basic assay is a kinetic hemolysis method (Weiler, E., Weiler, I. J., Sprenger, R. and Dittrich, B., Eur. J. Immunol. 1971. 1: 377) wherein binding of antibody to antigen‐equipped sheep red blood cells is measured. The binding reaction is inhibitable by hapten. Inhibition is not constant during the reaction but decreases with time. We therefore preferred to measure inhibition of initial rate of binding, because it reflects the decreased free antibody concentration at equilibrium with hapten.Hapten concentrations necessary to reach 50 % inhibition are shown to differ widely in different sera. Relation of inhibition data to average affinity of sera is discussed.
The i antigen complex: A new specificity unique to dividing human cells
Authors: Thomas D. B. 
Published: February 2007

AbstractEvidence is presented that erythroagglutinin, anti‐i, sera recognize a membrane antigen characteristic of dividing human cells. The antigen was present on fetal tissues, cultured cell lines and mitogen‐stimulated lymphocytes and absent from normal adult tissues. Cell synchrony studies with cultured lymphoblasts indicate that antigen expression is maximal during the S and G2 phases of the cell cycle. Absorption studies have shown that antibodies to this determinant are distinct from the erythroagglutinin activity of sera. The significance of “division antigens” in relation to oncofetal antigens is discussed.
Helper activity in vitro to a defined determinant
Authors: Henry Claudia , Trefts P. E. 
Published: February 2007

AbstractTo selectively induce a thymus‐derived (T) cell response to the hapten azophenylarsonate (Ars) we have injected BALB/c mice with the hapten covalently attached to mycobacteria. Spleen suspensions were then tested for evidence of Ars‐specific helper function by their ability to restore the in vitro anti‐lactoside (Lac) secondary response of T‐depleted Lac precursor cells. Helper activity was demonstrated when a double conjugate containing both Lac and Ars was added. Using column procedures which exclude adherent and Ig‐bearing cells, and treatment with anti‐T antiserum we excluded antibody as the responsible agent and implicated T cells. A comparison of the activity of hapten and protein‐specific helper cells revealed differences which may explain the infrequent demonstration of haptenspecific T function following immunization with hapten‐protein conjugates. The demonstration of Ars‐specific helper activity is interpreted as support for the contention that receptors on T cells are basically similar to those on antibody precursor cells.
T cell‐independent development of B memory cells
Authors: Diamantstein T. , Blitstein‐Willinger Eveline 
Published: February 2007

AbstractSpeen cells derived from sheep red blood cell (SRBC)‐primed nude mice gave a typical secondary response when challenged in vitro with SRBC in the presence of SRBC‐primed T cells. The results demonstrate that B memory cells of both IgM and IgG type develop in the absence of functioning T cells. Moreover, these results indicate that Θ‐antigen‐bearing cells, reactive to phytohemagglutinin (PHA) or concanavalin A (Con A), are not involved in the initiation of B cell triggering, but rather in the differentiation step leading to antibody‐forming cells.
A rapid micromethod for the detection of membrane‐associated antigens on monolayer cells by indirect immunofluorescence
Authors: Sorg C. 
Published: February 2007

AbstractTumor cells grown as monolayers in microtiter plates are used for the detection of surface antigens by indirect immunofluorescence. A procedure has been developed to keep the cells firmly attached during all reactions and washings. The test is read directly from the plates under a fluorescence microscope. A positive reaction is characterized by a coherent fluoresceinating ring encircling the cell membrane.
New Scalable Asymmetric Aminomethylation Reaction for the Synthesis of β2‐Amino Acids
Authors: Moumné Roba , Denise Bernard , Guitot Karine , Rudler Henri , Lavielle Solange , Karoyan Philippe 
Published: February 2007

Abstractβ‐Amino acids are useful tools in the design of peptidomimetics, and the development of new methods for their syntheses, particularly the synthesis of β2‐amino acids, remains an important challenge. Here we report a new scalable route based on the aminomethylation of silyl ketene N,O‐acetals by Mannich‐type iminium electrophiles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Regioselective Monobromination of Free and Protected Phenols
Authors: Pla Daniel , Albericio Fernando , Álvarez Mercedes 
Published: February 2007

AbstractA comparative study of the advantages of using THF compared with DMF in regioselective monobromination reactions of highly activated polyphenols, their ethers, and their tert‐butyl carbonate derivatives under mild conditions is described. Bromination with the common reagent N‐bromosuccinimide in polar solvents provided an easy and fast approach to aromatic electrophilic substitution at the most electronically favored positions with respect to O‐substituents. Tight control of the reaction temperature as well as short reaction times afforded better isolated yields (from 70 % to quantitative) of bromides when THF was used as the solvent instead of the classically used DMF. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Preparation of α‐Acetonylpiperidines from α‐Allylated Heterocycles by a Bromocyclocarbamation Reaction
Authors: Kuznetsov Nikolai Yu. , Khrustalev Victor N. , Godovikov Ivan A. , Bubnov Yuri N. 
Published: February 2007

Abstract2,6‐Disubstituted (alkyl)(allyl)‐ and diallylpiperidines containing C=C bonds in different environments can be selectively transformed into α‐acetonylpiperidines, including the alkaloid (±)‐6‐epipinidinone. The key step is the bromocyclocarbamation reaction of the N‐Boc‐protected α‐allylheterocycle with N‐bromosuccinimide. The bulky tert‐butyl group on the piperidine ring can affect the diastereoselectivity of the cyclization by 1,5‐asymmetric induction. The structure of one of the isolated diastereomers was established by X‐ray single‐crystal diffraction. The prepared bicyclic bromides were readily dehydrobrominated with tBuOK and the corresponding enols were hydrolyzed to α‐acetonylpiperidine hydrochlorides. The method presented is convenient and simple to perform. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Functionalized Single‐Walled Carbon Nanotubes Modified Microsensors for the Selective Response of Epinephrine in Presence of Ascorbic Acid
Authors: Valentini F. , Palleschi G. , Morales E. Lopez , Orlanducci S. , Tamburri E. , Terranova M. L. 
Published: February 2007

AbstractModified stainless steel microelectrodes (microwire diameter: 300 μm) were assembled using functionalized single‐walled carbon nanotubes (SWCNTs) deposited by the EPD method (electrophoretical deposition process). The functionalized SWCNTs, which covered the microelectrode surfaces, showed an improved sensitivity and selectivity toward the electrochemical detection of epinephrine. These chemical sensors hampered the voltammetric responses of ascorbic acid (AA) and uric acid (UA), while the electrochemical oxidation of epinephrine was significantly enhanced. Using the differential pulse voltammetry (DPV) technique, epinephrine showed a very well resolved peak centered around 240 mV, while 1 mM of AA (present in the same solution) was not detected. The corresponding permeability and permselectivity parameters were also evaluated for ascorbic acid and uric acid. To investigate the sensor selectivity, a comparative study performed using microsensors assembled with non functionalized carbon nanotubes, deposited on the microelectrode surfaces by a chemical vapor deposition (CVD) technique, was also carried out. This study was useful to highlight that the presence, or the absence of electrostatic barriers on SWCNT's walls (due to the presence of some chemical functional groups), can be able to control the electrochemical response of these sensors. This optimization resulted in microsensors with a good linear range (2–100 μM) epinephrine; a good sensitivity (28.1 A M−1 cm−2) and interelectrodes reproducibility (RSD%=7.0, n=6), a detection of limit (LOD=3σ) of 2 μM; a response time of 6 s; a significant operational stability (of 13 hours in continuous working conditions) and long term stability (1 month).
Electrochemical and Surface Properties of Multilayer Films Based on a Ru2+ Metallodendrimer and the Mixed Addenda Dawson Heteropolyanion
Authors: Zynek Monika , Serantoni Marina , Beloshapkin Sergey , Dempsey Eithne , McCormac Timothy 
Published: February 2007

AbstractThe successful formation of organized multilayer assemblies, formed from the Dawson type mixed addenda heteropolyanion, [P2W17 VIVO62]8−, and a Ru2+ pentaerythritol based metallodendrimer, [RuDen]8+, has been achieved on carbon electrode surfaces. Cyclic voltammetric studies of the assembly across a wide pH domain, namely, 2 to 7 was possible. Upon redox switching, the redox couples associated with the RuIII/II redox system, of the cationic metallodendrimer, and both the VIV/V and the tungsten‐oxo framework of the heteropolyanion, were clearly evident. The multilayer assembly exhibited good stability towards both redox cycling and soaking over extended periods of time in aqueous buffer solutions. In addition, the constructed multilayer films were found to be quite compact in nature. The films were further characterized by X‐ray photoelectron spectroscopy (XPS) to determine their elemental composition. Surface morphology of the multilayer films was determined by atomic force microscopy (AFM). The electrocatalytic reduction of iodate by the multilayer film was also investigated.
A Protein‐Resistant Matrix for Electrochemical Based Recognition Assays
Authors: Pallarola Diego , Domenianni Luis , Priano Graciela , Battaglini Fernando 
Published: February 2007

AbstractIn this work, two well known polymers, carboxymethyl dextran and poly(ethyleneglycol), are used for easily producing a platform for electrochemical affinity assays, avoiding nonspecific adsorption of proteins. In this way, modified electrode surfaces able to bind a recognition agent are constructed through simple and reliable reactions.
Catalytic Adsorptive Stripping Voltammetry of Germanium(IV) in the Presence of Gallic Acid and Vanadium(IV)‐EDTA
Authors: Li Yi‐Heng , Chen Xin‐Huan , Huang Mei‐Hua , Zhou Fang‐Qin 
Published: February 2007

AbstractA highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO4 (pH1.6), 6.0×10−3 mol/L GA, 3.0×10−3 mol/L V(IV), 4.0×10−3 mol/L EDTA, an accumulation potential of −0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10−11 to 1.0×10−8 mol/L and the detection limit is 2×10−11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10−10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results.