bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD4 and CD8 accessory molecules function through interactions with major histocompatibility complex molecules which are not directly associated with the T cell receptor‐antigen complex
Authors: Lustgarten Joseph , Waks Tova , Eshhar Zelig 
Published: March 2007

AbstractBoth the subset‐specific, CD4 and CD8 T cell accessory molecules and the antigen‐specific T cell receptor (TcR) interact with major histocompatibility complex (MHC) class I and class II molecules on the surface of antigen‐presenting cells. We analyzed whether the CD4/CD8 molecules exert their accessory function through binding with the same MHC molecules which participate in the TcR‐antigen‐MHC complex. We utilized a CD4−, CD8−, class I‐allospecific T cell hybridoma which functionally manifests both cytotoxic T lymphocyte (CTL) and T helperl (Th1) phenotypes, and rendered it bispecific by transfecting it with genes encoding either a class II‐restricted, 2,4,6‐trinitrohenyl (TNP)‐I‐Ad‐specific TcR or a non‐MHC‐restricted chimeric TcR. composed of a variable part of an anti‐TNP antibody. Expression of either CD4 or CD8 transgenes in these hybridomas enhanced and augmented their reactivity towards the appropriate target cells regardless of the type of TcR‐MHC interaction. Thus, class I‐specific responses could be enhanced through CD4‐class II interactions, and class II‐restricted responses could be augmented through CD8‐class I interactions. Furthermore, these accessory molecules also potentiated TNP‐specific responses by the chimeric TcR which is MHC unrestricted. The accessory molecules facilitated both interleukin 2 (IL 2) production and cytolytic activity by shortening the activation time and rendering the cells responsive to lower antigenic stimuli. The degree of activity of the T cell hybridomas correlated with the level of accessory molecule expression and was not related to the effector function mediated by the cells. Anti‐CD4 or ‐CD8 antibodies completely inhibited the activity of transfectants expressing the corresponding accessory molecule, regardless of the MHC type of the TcR interaction. Such antibodies blocked direct TcR stimulation provided by either anti‐T3/Ti antibodies or lectins. but could not inhibit the activation through agents that bypass the TcR such as phorbol 12‐myristate 13‐acetate plus ionophore. Taken together, these studies demonstrate that the CD8/CD4 molecules can exert their accessory function through interactions with MHC molecules which are not directly associated with the TcR‐Ag‐MHC complex, and that this accessory effect is associated with TcR‐mediated triggering at an early stage of the signaling process and is not related to the effector mechanism assigned to the CD4 and CD8 T cell subsets.
Induction of nitric oxide synthase in rat peritoneal neutrophils and its inhibition by dexamethasone
Authors: McCall Thérèse B. , Palmer Richard M. J. , Moncada Salvador 
Published: March 2007

AbstractRat peritoneal polymorphonuclear leukocytes (PMN) elicited with oyster glycogen contain a Ca2+‐independent nitric oxide (NO) synthase which is induced in vivo in a time‐dependent manner. When washed PMN containing low levels of enzyme activity were cultured ex vivo further expression of NO synthase was observed. This was inhibited by cycloheximide indicating that de novo synthesis of the enzyme occurred during the ex vivo incubation. Enzyme activity was enhanced by interferon (IFN)‐γ, but not by tumor necrosis factor (TNF)‐α when added ex vivo. However, IFN‐γ and TNF‐α synergized to increase further the expression of NO synthase.Treatment of rats with dexamethasone inhibited the induction of NO synthase in elicited PMN. This treatment reduced the accumulation of PMN by approximately 30%, without affecting cell viability. Dexamethasone also inhibited the induction of the NO synthase ex vivo in a concentration‐dependent manner. Furthermore, the enhanced enzyme activity following treatment of PMN with cytokines was also inhibited by dexamethasone. Once induced, dexamethasone did not affect enzyme activity. These data indicate that PMN elicited in the rat peritoneum with oyster glycogen express an NO synthase in vivo and ex vivo. The induction of the enzyme can be further stimulated ex vivo with IFN‐γ and TNF‐α and inhibited by dexamethasone. The inhibition of the induction of NO synthase in the PMN by dexamethasone may contribute to the anti‐inflammatory activity of this and other glucocorticoids.
Ontogeny of T cell maturation in LEC mutant rats which bear a congenital arrest of maturation from CD4+CD8+ to CD4+CD8− thymocytes
Authors: Agui Takashi , Sakai Tohru , Matsumoto Kozo 
Published: March 2007

AbstractLEC rats bear a congenital deficiency in CD4+CD8− thymocytes and peripheral CD4+ T cells, and consequently a deficiency in Th cell functions. Ontogeny of T cell maturation in normal and LEC mutant rats was, therefore, investigated. Prenatal development of thymocytes in normal rat strains, with respect to the expression of CD4/CD8 and TcR antigens, was similar to that of mice except that its kinetics was delayed by approximately 24 h. The kinetics of T cell maturation in LEC rats was comparable with that of normal rats up to day 19 of gestation, at which stage double‐negative thymocytes (CD4−CD8−) developed into double positives (CD4+CD8+) through immature CD4−CD8+ subset. At day 19 of gestation in LEC as well as normal rats, double positives occupied ∼80% of the total thymocytes, half of which were TcR‐dull positive, indicating that TcR was normally rearranged and then expressed in LEC rat thymocytes. These data indicate that double negatives normally mature into at least double positives in LEC rats. Both single positives appeared after day 19 of gestation in normal rats. while in LEC rats CD4+CD8− cells did not appear, suggesting that the deficiency in CD4+CD8− cells is due to a congenital arrest of maturation from CD4+CD8+ to CD4+CD8− cells, but not due to a postnatal deletion.
Is there really a “lack of natural tolerance to allotypic γ‐globulins in rabbits”?
Authors: Meier Daniel , Kelus Andrew S. 
Published: March 2007

AbstractWe present data of extended studies on the possibility of maternally derived allotype Ig inducing a state of natural immunological tolerance to a non‐inherited allotype in the offspring. Rabbits homozygous at the a locus, encoding allotypes in the variable region of immunoglobulin heavy chains, and rabbits homozygous at the unliked b locus, encoding allotypes of the constant region of x1 light chains, were immunized at the age of 2 months against the non‐inherited allotype of their heterozygous mothers to which they had been exposed in utero and in early life. As control, we immunized rabbits of the same Ig phenotype but born to homozygous mothers, and therefore not exposed to that allotype. Immunization was done in a3/a3 offspring of either a1/a3 or a3/a3 mothers, by injecting al IgG, and in b6/b6 offspring of b4/b6 or b6/b6 mothers, by injecting b4 IgG. The IgG was injected either in a soluble form or emulsified in adjuvant. Injection of soluble IgG elicited only a low response, if any, revealing no differences between the various groups. All rabbits responded upon immunization with IgG in adjuvant.We have not found any good evidence for natural tolerance to a non‐inherited allotype, although progeny of a1/a3 mothers had slightly decreased responses to al. On the contrary, progeny of b4/b6 mothers responded even better than offspring of b6/b6 mothers, upon such immunization with b4.To induce tolerance experimentally, we injected newborn rabbits, either from heterozygous a1/a3 or from homozygous a3/a3 mothers, with a1 serum or IgG. Newborn of heterozygous b4/b6 or of homozygous b6/b6 mothers were injected with b4 serum or IgG in the same way. Such treatment resulted in partial tolerance to each allotype.In an attempt to amplify the tolerizing effect of the maternal al Ig, we injected newborn rabbits of a1/a3 mothers with the serum of their mother. The response upon subsequent immunization with a1 allotype of another individual did not differ significantly from the response of control rabbits.The response was much poorer when rabbits were injected with nonmaternal tolerogen at birth, and when the same Ig preparation was used as immunogen.In a control experiment, neonatal injection of xenogeneic proteins, human IgG or bovine serum albumin, clearly resulted in tolerance. We speculate that tolerance to allotypes is established in the T cell repertoire only but bypassed by recognition of idiotypic determinants on antigen molecules by helper T cells, which trigger anti‐allotype antibody formation by allotype‐specific B cells. The end result of it is a lack of natural tolerance.
Interferon‐γ inhibits serotonin release from mouse peritoneal mast cells
Authors: Coleman John W. , Buckley Mark G. , Holliday Mark R. , Morris Alan G. 
Published: March 2007

AbstractConditioned medium (CM) from concanavalin A‐activated mouse spleen cells inhibits antigen‐induced 5‐hydroxytryptamine (5‐HT) release from mouse peritoneal mast cells when added for 24 or 48 h to cell cultures containing monoclonal IgE sensitizing antibody. We present the following evidence that the spleen cell‐derived inhibitory factor is interferon‐γ (IFN‐γ): (a) CM from Con A‐activated spleen cells and from Chinese hamster ovary (CHO) cells transfected with the murine (Mu)IFN‐γ gene both produced a graded inhibition of 5‐HT release when added to peritoneal cell cultures containing IgE and subsequently challenged with antigen; (b) the relative inhibitory potency of the two preparations corresponded to their relative IFN content as determined by antiviral bioassay; (c) the inhibitory activity of spleen cell CM and of CM from IFN‐γ gene‐transfected CHO cells was abolished by treatment with a rat monoclonal MuIFN‐γ‐neutralizing antibody, i.e. 5‐HT release returned to control levels, and (d) a highly immunopurified preparation of recombinant MuIFN‐γ retained the inhibitory activity, and was active at concentrations as low as 2 U/ml. The inhibitory activity of IFN‐γ appeared to be a direct effect of the cytokine on mast cells, since CM generated for different time periods from unfractionated peritoneal cells treated with purified recombinant MuIFN‐γ contained no inhibitory activity other than IFN‐γ itself, as demonstrated by neutralization of the cytokine with monoclonal antibody. Furthermore, purified recombinant MuIFN‐γ was equally active on mast cells enriched by density centrifugation up to 95% purity as on unfractionated peritoneal cells (1%–2% mast cells). Purified recombinant MuIFN‐γ inhibited 5‐HT release induced by a range of different cell activators, namely antigen, anti‐IgE, compound 48/80 and calcium ionophore A23187. Hence inhibition is not specific to IgE‐dependent activation of mast cells, but seems to be directed more generally at the secretory process of these cells.
Rat “first‐wave” mature thymocytes: Cycling lymphoblasts that are sensitive to activation‐induced cell death but rescued by interleukin 2
Authors: Lawetzky Alexandra , Kubbies Manfred , Hünig Thomas 
Published: March 2007

AbstractThe sequential appearance of thymocyte subsets in rat ontogeny was studied using the surface markers CD4, CD8, and the α/β T cell receptor (here referred to as TcR). It was noted that the first TcRhigh thymocytes, appearing around birth, are not resting lymphocytes but cycling blast cells. These “first wave” TcRhigh cells are medullary in location and predominantly of the CD4/CD8 “single‐positive” phenotype. Only about 5% express the light chain of the interleukin (IL)2 receptor, indicating that binding of IL 2 to high‐affinity receptors is not driving proliferation of these blasts.Newborn TcR high blast cells were purified and analyzed in vitro. When cultured without further additions, they rapidly stopped cycling. Stimulation with cross‐linked anti‐TcR monoclonal antibody plus IL 2 resulted in vigorous and rapid proliferation that exhibited accelerated kinetics as compared to peripheral resting T cells. In contrast, TcR cross‐linking without exogenous IL 2 induced cell death. This TcR‐induced cell death involved fragmentation of DNA characteristic of apoptosis that was readily detectable within 18 h of culture. Addition of IL 2 to these short‐term cultures prevented TcR‐induced DNA fragmentation. Together, these results suggest that in newly formed TcRhigh thymocytes, TcR engagement results in clonal deletion if the IL 2 receptor remains unoccupied but allows clonal expansion if IL 2 is provided. This mechanism may be operative in the establishment of self‐tolerance during T cell development.
Enhancement of IgG production elicited in mice by treatment with anti‐CD8 antibody
Authors: Coutelier Jean‐Paul 
Published: March 2007

AbstractInjection of an anti‐CD8 monoclonal antibody into mice was followed by an increase in the production of immunoglobulins of the IgG1, IgG2a, and IgG2b, but neither the IgG3 nor the IgM isotypes. A maximal effect was observed 6 days after administration of 10μg antibody. However, no modification of spleen cell proliferation was elicited by the anti‐CD8 treatment. Virally induced IgG2a and IgG2b secretion remained unchanged in mice infected with lactate dehydrogen‐ase‐elevating virus that received a concomitant injection of anti‐CD8 antibody, whereas an enhancement of IgG1 was observed. Simultaneous treatment with an anti‐CD4 antibody abrogated the immunoglobulin secretion triggered by anti‐CD8. These results suggest that immunoglobulin production in unmanipulated mice is controlled by CD8+ lymphocytes.
Thymic epithelial cell‐derived supernatants sustain the maturation of human prothymocytes: Involvement of interleukin 1 and CD23
Authors: Dalloul Ali H. , Fourcade Christine , Debré Patrice , Mossalayi M. Djavad 
Published: March 2007

AbstractDuring their development, human CD7+ lymphoid stem cells migrate into the thymus where, following intimate contact with thymic tissue, they proliferate and differentiate into functionally mature T lymphocytes. In this study, we investigated the effect of thymic epithelial cell‐derived supernatants (TEC‐SN) on early CD7+CD2−CD3− thymocytes. Our results indicate that TEC‐SN are able to promote CD2 and CD3/TcR α/β expression by CD7+ precursors. This activity correlated with soluble CD23 and interleukin 1 levels in TEC‐SN. Furthermore, monoclonal antibodies to these cytokines decreased in vitro maturation of prothymocytes. Thus, in addition to cell‐cell interactions, human TEC produce cytokines able to support early steps of thymocyte differentiation.
Opposing effects of protein tyrosine kinase inhibitors on the monoclonal antibody induced internalization of CD3 and CD4 antigens
Authors: Thuillier Laure , Pérignon Jean‐Louis , Selz Françoise , Griscelli Claude , Fischer Alain 
Published: March 2007

AbstractWe have previously demonstrated that the monoclonal antibody (mAb)‐induced moduiation of CD3 and CD4 antigens from the surface of human peripheral blood lymphocytes is not dependent from protein kinase C activity (Thuillier et al., Eur. J. Immunol. 1990. 20: 1197). In the present report we study the effect of genistein and of herbimycin A, two potent inhibitors of protein tyrosine kinases (PTK), on the mAb‐induced modulation of CD3 and CD4 surface antigens. Both genistein and herbimycin inhibited the mAb‐induced internalization of CD3 and, in contrast, facilitated that of CD4 antigen. These results indicate that the mAb‐induced modulation of CD3 is essentially dependent on the PTK pathway, whereas PTK appear to negatively regulate the mAb‐induced modulation of CD4.
Glucocorticoids suppress the production of interleukin 4 by human lymphocytes
Authors: Wu Chang You , Fargeas Christine , Nakajima Toshiharu , Delespesse Guy 
Published: March 2007

AbstractGiven that glucocorticoids (GCS) were reported to increase the production of interleukin 4 (IL4) by mouse T cells and that GCS are widely used to treat allergic diseases it was important to examine the effect of these agents on IL4 production by human lymphocytes. We here demonstrate that the production of IL4 by human lymphocytes is markedly inhibited by small concentrations of hydrocortisone. The suppression is observed at the protein and at the mRNA levels and it is not secondary to the GCS‐induced inhibition of IL2 production.
Supramolecular Chemistry and Anion Binding in Palladium(II) and Silver(I) Complexes Containing N,N′‐Dipyridylxanthene‐4,5‐dicarboxamide Ligands
Authors: Yue Nancy L. S. , Jennings Michael C. , Puddephatt Richard J. 
Published: March 2007

AbstractTwo new ligands, 2,7‐di‐tert‐butyl‐9,9‐dimethyl‐N,N′‐di(3‐pyridyl)‐ (1) and ‐N,N′‐bis[(3‐pyridyl)methyl]xanthene‐4,5‐dicarboxamide (2), and their complexes with palladium(II) and silver(I) are reported. Intramolecular hydrogen bonding orients the ligands so as to favour formation of macrocyclic complexes, and the structures of [Pd2X4(μ‐1)2] (3a), X = Cl; (3b) X = Br, and [Ag2(μ‐2)2](CF3SO3)2 (5a) are reported. Intermolecular hydrogen bonding can also occur and can lead to supramolecular self‐assembly to give sheet 3a or ribbon 5a structures, or serve to bind anions or solvent molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Reactivity of Ruthenium(II) and Copper(I) Complexes that Possess Anionic Heteroatomic Ligands: Synthetic Exploitation of Nucleophilicity and Basicity of Amido, Hydroxo, Alkoxo, and Aryloxo Ligands for the Activation of Substrates that Possess Polar Bonds as well as Nonpolar C–H and H–H Bonds (Eur. J. Inorg. Chem. 9/2007)
Authors: Gunnoe T. Brent 
Published: March 2007

AbstractThe cover picture shows the disruption of amido‐ and alkoxo‐to‐metal π‐donation because of a filled dπ manifold, which occurs for metal centers in low oxidation states and which renders the anionic amido, alkoxo and related ligands highly reactive. The low oxidation states decrease the predilection toward metal‐center reduction and, as a result, tend to promote “even‐electron” chemistry over odd‐electron radical chemistry that is based on net single‐electron reduction of the metal. For RuII and CuI complexes, evidence for the enhanced reactivity of the heteroatomic ligands is derived from acid/base reactions as well as from nucleophilic additions. The combination of a Lewis acid metal center and a basic/nucleophilic heteroatomic ligand (amido, hydroxo, alkoxo, etc.) can be exploited for the activation of substrates that possess polar and nonpolar bonds, for example for metal‐mediated C–H activation and for catalytic hydroamination and hydroalkoxylation of activated olefins. Details are presented in the Microreview by T. B. Gunnoe on p. 1185 ff.
Efficient One‐Pot Synthesis of Enantiomerically Pure 2‐(Hydroxymethyl)morpholines
Authors: Breuning Matthias , Winnacker Malte , Steiner Melanie 
Published: March 2007

AbstractAn efficient and convenient one‐pot procedure for the synthesis of enantiomerically pure 2‐(hydroxymethyl)morpholines with a widely variable substitution pattern was developed. Addition of chiral β‐amino alcohols to (S)‐ or (R)‐epichlorohydrin in the presence of LiClO4 afforded the corresponding chloro alcohols, which were treated with NaOMe to give the epoxides and, by subsequent intramolecular cyclization, the target compounds in good yields (57–77 %). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
On‐line coupling of SPE and CE‐MS for peptide analysis
Authors: Tempels F. W. Alexander , Underberg Willy J. M. , Somsen Govert W. , de Jong Gerhardus J. 
Published: March 2007

AbstractAn on‐line SPE‐CE‐MS system has been developed for the analysis of peptides. Analytes are preconcentrated using a C18 microcolumn (5×0.5 mm id), and then introduced into the CE system via a valve interface. The CE system with a Polybrene‐poly(vinylsulfonate) bilayer coated capillary is combined with an ion‐trap mass spectrometer via ESI using a coaxial sheath‐liquid sprayer. The on‐line coupling of the SPE and CE step by the valve interface is advantageous because it allows an independent functioning of the system parts. Optimization of the SPE‐CE system was performed using UV detection. Subsequently, the SPE‐CE system has been coupled to the ion‐trap mass spectrometer. Test solutions with enkephalin peptides (50 ng/mL) were used for evaluation of system performance. Repeatability of effective mobility and peak area ratio of the two enkephalins were within 1.2% and 9% RSD, respectively. The analysis of 1:1 v/v diluted cerebrospinal fluid samples spiked with enkephalin peptides showed detection limits (S/N = 3) in the range of 1.5–3 ng/mL (around 5 nM), which were similar to those obtained for enkephalin test solutions. Moreover, the potential of the on‐line SPE‐CE‐MS system was demonstrated by the analysis of a cytochrome C digest. Some hydrophilic peptides did not show sufficient retention on the SPE column, and were lost during preconcentration. Nonetheless, positive identification of the protein was achieved, indicating the feasibility of the system for proteomics.
Identification of a novel human papillomavirus (HPV97) related to HPV18 and HPV45
Authors: Chen Zigui , Fu Leiping , Herrero Rolando , Schiffman Mark , Burk Robert D. 
Published: March 2007

AbstractHuman papillomavirus (HPV) type 97 was identified and the genome was cloned from cervicovaginal cells of a Costa Rican woman with a normal Pap smear. The HPV97 L1 open reading frame (ORF) was most closely related to HPV45 (84% identity) and HPV18 (79% identity), placing it into the high‐risk α7 species. Ectopic expression of the HPV97 E6 and E7 proteins significantly decreased steady state p53 and pRb levels using an in vitro cotransfection assay, respectively. These data suggest that HPV97 shares a most recent common ancestor with HPV18 and HPV45 and should be evaluated in cancer specimens from different geographic populations. © 2007 Wiley‐Liss, Inc.
Cell exfoliation in the human colon: Myth, reality and implications for colorectal cancer screening
Authors: Loktionov Alexandre 
Published: March 2007

AbstractColonocyte exfoliation in the human colon constitutes a unique mechanism of cell population control that can undergo significant changes under different physiological and pathological conditions. Being closely related to the apoptosis and anoikis, cell exfoliation from colonic epithelium appears to be a relatively rare event in normal conditions, but its rate dramatically increases in neoplasia, when cell removal by apoptosis in situ does not function properly. Several studies show that significant numbers of exfoliated colonocytes are not lost in the faecal contents of the gut, but retained in the mucocellular layer overlying colonic mucosa. Recent observations allow hypothesizing that the mucocellular layer containing exfoliated colonocytes may gradually migrate distally, eventually leading to the accumulation of the cells exfoliated from malignant colorectal tumours on the surface of the rectal mucosa. Implications of exfoliated colonocyte analysis to colorectal cancer screening and early diagnosis are discussed. © 2007 Wiley‐Liss, Inc.