bluuebunny/crossref_metadata_2025 huggingface dataset:
Autoantibody Production in Healthy Elderly People is not Promoted by Interleukin‐10 Although This Cytokine is Expressed in Them by a Peculiar CD8+CD3+ Large Granular Cell Subpopulation
Authors: LLORENTE L. , RICHAUD‐PATIN Y. , ALVARADO C. , VIDALLER A. , JAKEZ‐OCAMPO J.
Published: November 2003

Healthy elderly people tend to have autoantibodies in their sera. These antibodies, not being associated with any clinical manifestation, have been considered as natural autoantibodies. In systemic lupus erythematosus, as well as in rheumatoid arthritis, the presence of autoantibodies characteristic of these diseases (anti‐dsDNA and rheumatoid factor, respectively) depends on the endogeneous production of IL‐10. The same could hold true for autoantibodies found in healthy elderly individuals. In the present work, the authors analysed whether an increased production of IL‐10 contributed to the production of autoantibodies in elderly people. The authors found that there is neither increased in vivo gene expression nor augmented production of IL‐10 by peripheral blood mononuclear cells from elderly women even if they do produce autoantibodies. The authors further sought to determine if the production of autoantibodies is inhibited in vitro by adding an anti‐IL‐10 MoAb to cell cultures and found that it is not. Despite these negative findings of a role for IL‐10 in the production of autoantibodies in elderly people, the authors investigated which cells produce IL‐10. In so doing they found that intracellular IL‐10 expression occurred exclusively in monocytes in young female controls, but in elderly females it involved also CD8+CD3+ large granular cells. These results indicate that autoantibody production in healthy aged individuals is IL‐10 independent.
T Cells are Unresponsive to Transgenic MHC Class II Molecules Expressed on Pancreatic β Cells
Authors: Pilstro¨m B. , Bo¨hme J.
Published: November 2003

It has been proposed that the autoimmune attack on the pancreatic β cells leading to insulin‐dependent diabetes mellitus can be caused by the expression of MHC class II molecules on the β cells. Transgenic mice expressing normal levels of allogeneic MHC class II Ak on the β‐cell surface (IP‐Ak) do not develop either insulitis or diabetes, yet these mice are not tolerant to Ak when expressed on normal antigen‐presenting cells. The authors have stimulated T cells from IP‐Ak mice in vitro with Ak‐expressing β cells. Mice were also primed in vivo in order to facilitate the antiallogeneic response. The authors found that neither IP‐Ak positive nor IP‐Ak negative mice were able to respond to Ak‐expressing β cells, and that in vivo priming does not overcome this inability. They suggest that β cells do not act as antigen‐presenting cells, probably due to inability of delivering costimulatory signals. This strengthens the notion that MHC class II expression per se is not sufficient to induce an autoimmune attack on the β cells.
Selective Lysis of Activated Cells in Oncorna Virus Infection
Authors: Biasi G. , Facchinetti A. , Mezzalira S. , MacDonald H. R.
Published: November 2003

The authors devised a cytotoxic assay based on cytofluorometric analysis of target surface markers in order to compare lysis exerted in vitro by cytotoxic T lymphocytes (CTLs) on different cell subsets in the context of a single lymphoid target cell population. Using this assay, the authors evaluated when oncorna virus‐infected lymphocytes become a suitable target for virus‐specific T cell effectors. A lymphocyte population from Moloney‐murine leukaemia virus (M‐MuLV)‐infected (carrier) mice, in which the proliferation of selective Vβ T‐cell receptor (TCR) families was induced in response to Mlsa encoded antigens, was utilized as a target. The authors observed that a virus‐specific T cell clone exerted lytic activity preferentially against activated cell subsets. Moreover, virus‐specific CTLs generated in mixed leucocyte tumour cell cultures (MLTC) were also able to impair the concomitant anti‐Mlsa response of lymphocytes from M‐MuLV carrier mice. It was found that the proliferative status of oncorna virus‐infected target cells played an important role in limiting the in vitro efficacy of the immune response, and it is speculated that this phenomenon might represent an in vivo escape mechanism from immunosurveillance.
Role of Tyrosine Kinase Enzymes in TNF‐α and IL‐1 Induced Expression of ICAM‐1 and VCAM‐1 on Human Umbilical Vein Endothelial Cells
Authors: MAJEWSKA E. , PALEOLOG E. , BAJ Z. , KRALISZ U. , FELDMANN M. , TCHÓRZEWSKI H.
Published: November 2003

The aim of this study was to analyse the potential roles of protein kinase enzymes in tumour necrosis factor‐α (TNF‐α) and interleukin‐1 (IL‐1) induced expression of the adhesion molecules intercellular adhesion molecule‐1 (ICAM‐1) and vascular cell adhesion molecule‐1 (VCAM‐1) on human umbilical vein endothelial cells (HUVEC). The authors observed a marked increase in ICAM‐1 and VCAM‐1 expression on HUVEC stimulated for 24 h by TNF‐α (10 ng/ml) or IL‐1 (20 ng/ml). Pre‐treatment of HUVEC for 30 min with protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A (10 μg/ml and 0.5 μg/ml, respectively) before stimulation with IL‐1 did not affect the expression of these molecules. Similar results were observed with respect to VCAM‐1 expression on HUVEC stimulated by TNF‐α. In contrast, pre‐incubation of HUVEC with PTK inhibitors prior to the addition of TNF‐α significantly enhanced subsequent expression of ICAM‐1, although spontaneous expression of ICAM‐1 on unstimulated HUVEC was unaffected. Western blot analysis demonstrated a significant increase in phosphorylated tyrosine protein levels in HUVEC stimulated by TNF‐α, and significantly lower levels of these proteins in TNF‐α stimulated HUVEC pre‐treated with PTK inhibitors. These results demonstrate that IL‐1 induced ICAM‐1 and VCAM‐1 expression does not result from activation of PTK‐dependent pathways. In the case of TNF‐α induced responses, the selective co‐stimulatory effect of this cytokine in combination with PTK inhibitors on ICAM‐1 expression suggests a complicated intracellular pathway of TNF‐α induced ICAM‐1 expression, possibly involving down‐modulation of increases in ICAM‐1 by PTK enzymes.
Suppression of Alternative Complement Pathway Activity by Radiographic Contrast Media
Authors: MIKKONEN R. , LEHTO T. , KOISTINEN V. , ARONEN H. J. , KIVISAARI L. , MERI S.
Published: November 2003

The authors examined the effect of four different kinds of contrast media (ionic/non‐ionic, monomer/dimer) on the activation of the complement (C) system (haemolytic activity and anaphylatoxin generation) in vitro. In addition, the authors compared the effect of contrast media on inulin‐mediated generation of the anaphylatoxin derivative C3a des Arg in sera from urticarial reactors and their non‐reacting controls. It was observed that the incubation of commercial iohexol, ioxaglate, iodixanol and meglumin amidotriz solutions in normal human serum (NHS) resulted in a dose‐dependent decrease in the haemolytic activity of the alternative C pathway. Contrary to expectations the contrast media did not activate C in NHS. Instead, inulin‐induced generation of C3a des Arg was inhibited by all the four contrast media. The strongest inhibitor was ioxaglate, an ionic dimer. No significant difference between the urticarial reactors and non‐reactors in the inhibition of C3a des Arg generation was observed. In analyzing the mechanism of C inhibition we found that the contrast media solutions, particularly the ionic ones, prevented formation of the alternative pathway C3 convertase, C3bBb, by inhibiting the binding of factor B to surface‐associated C3b molecules. The results suggest that the previously observed decrease in haemolytic C titres by contrast media is due to direct suppression of C activity rather than activation‐induced consumption.
Lack of Correlation Between Membrane CD30 Expression and Cytokine Secretion Pattern in Allergen‐Primed Naive Cord Blood T‐Cell Lines and Clones
Authors: SPINOZZI F. , AGEA E. , PIATTONI S. , FALINI B. , GRIGNANI F. , BERTOTTO A.
Published: November 2003

Various surface molecules are expressed by activated T cells. Among them, the CD30 antigen has been proposed as a reproducible marker that identifies a subset of differentiated and/or activated T lymphocytes that produce T helper (Th)‐2‐type cytokines, i.e. interleukin (IL)‐4 and IL‐5. However, because CD30 has mainly been detected on established T‐cell clones, it is still unclear whether a priming allergen and/or cytokine can induce its membrane expression on naive T cells, perhaps in parallel with the up‐regulation of other relevant activation markers, such as CD25, HLA‐DR and L‐selectin. It is also unknown whether proper allergen stimulation affects the cytokine secretion pattern by CD30+ T‐cell clones derived from antigen‐unprimed (naive) T lymphocytes. More information on these questions was sought by adopting a model that used cord blood as a source of virgin T cells and exposing them to native cypress allergen or cytokine (IL‐2 or IL‐4) stimulation, as well as to conventional polyclonal activators such as PHA or anti‐CD3. Peripheral blood MC from four adult cypress‐sensitive patients was also assayed and used as controls for all culture experiments. Freshly isolated cord and adult T cells did not express the CD30 antigen on their membrane. Many of the stimulating agents tested were able to up‐regulate the expression of CD30. However, despite high expression of this molecule, cloned allergen‐specific cord CD4+ T lymphocytes were unable to produce IFN‐γ and/or IL‐4. In contrast, they retained the capability to produce IL‐2. Thus, expression of the CD30 antigen on virgin T cells does not correlate with a polarized model of T helper (Th)‐1 or Th‐2 cytokine‐producing cells, suggesting that these types of lymphokine‐secreting lymphocytes are not a paradigmatic example of T‐cell subpopulations that display stable phenotypical features.
Age‐Associated Changes in the Cellular Composition of the Human Adenoid
Authors: MATTILA P. S. , TARKKANEN J.
Published: November 2003

Histological investigations suggest that the size and number of lymphoid follicles of the adenoids and tonsils decrease during ageing. The mechanisms underlying the histological changes are unknown. The authors have analysed the frequency of lymphocyte subpopulations in the adenoids by flow cytometry. The proportion of B lymphocytes decreased and the proportion of T lymphocytes of all mononuclear cells increased with age. Of all B lymphocytes the proportion of CD38+, surface IgD− B lymphocytes representing the germinal centre cell phenotype, decreased and the proportion of CD38−, IgD− B lymphocytes representing the mature B lymphocyte phenotype, increased with age. The expression of CD23, a cell surface molecule associated with activation of follicular mantle IgD+ B lymphocytes, did not change with increasing age. The results imply that the involution of the adenoid is associated with a decreased germinal centre reaction and relative accumulation of mature B cells in the adenoidal tissue, as analysed by three‐colour flow cytometry.
Human Polyreactive IgM Monoclonal Antibodies with Blocking Activity Against Self‐Reactive IgG
Authors: Melero J. , Tarragó D. , Núñez‐Roldán A. , Sánchez B.
Published: November 2003

Natural IgM antibodies have been found to be involved in the control of IgG reactivity in normal serum. The authors investigated the blocking activity of four human IgM monoclonal antibodies (BY‐2, BY‐7, BY‐10 and IRM‐7) derived from B‐cells from blood samples of three renal dialysis patients, which had shown multispecific properties similar to those observed for natural polyreactive autoantibodies. To achieve this, competitive inhibition assays were performed with these MoAbs on the binding of IgG purified from a healthy control, three patients with SLE, and two patients with autoimmune thyroiditis, to histone, dsDNA, RNP and thyroglobulin. MoAbs inhibited binding of self‐reactive IgG to histone and dsDNA, but not to thyroglobulin or RNP, of natural and active or inactive phase disease‐associated autoreactive IgG. The inhibitory effect of the MoAbs was mediated by V‐region dependent interactions with autoreactive IgG, as shown by the ability of these MoAbs to block the binding of F(ab′)2 fragments of autoreactive IgG to antigens (histone and dsDNA). The blocking of autoantibody activity was dose‐dependent with maximal inhibition occurring at a specific molar ratio between the patient's IgG and a given MoAb. In contrast, MoAbs did not inhibit binding of IgG alloantibodies present in the sera of four polytransfused renal dialysis patients to target antigens on the surface of different cells. These results support the concept of a functional idiotypic network regulating autoimmune responses, and suggest that the IgM MoAbs under study may be natural polyreactive antibodies belonging to the physiological network of autoantibodies with highly connected V‐regions, capable of binding and functionally neutralizing V‐regions of natural and pathologic autoantibodies.
T‐Helper Cell Tolerance to Ubiquitous Nuclear Antigens
Authors: Nakken B. , Davis K. E. , Pan Z. J. , Bachmann M. , Farris A. D.
Published: November 2003

Systemic autoimmune diseases are characterized by the development of antinuclear autoantibodies. In order to understand the immunologic events leading to the development of such antibodies, knowledge of mechanisms of immune tolerance to nuclear antigens is required. By utilizing adoptive T‐cell transfer strategies with transgenic mouse models expressing nuclear neo‐self antigens, T‐cell tolerance to the lupus‐related nuclear antigens human La and nRNP A has been demonstrated. These findings also indicate the existence in normal animals of autoreactive B cells continuously presenting nuclear antigen, suggesting that nuclear antigens are not sequestered from the immune system. Investigations of CD4+ T‐cell tolerance to non‐nuclear antigens have revealed a number of mechanisms that protect the host from autoreactivity, including autoreactive T‐cell deletion, regulatory T‐cell development and anergy induction. Recent studies using T‐cell receptor and neo‐self nuclear antigen transgenic mice are revealing the importance of such mechanisms in maintaining tolerance to nuclear antigens. Mechanisms of tolerogenic antigen presentation, identification of tolerogenic antigen source(s) and the pathways leading to loss of tolerance to nuclear antigens in systemic autoimmune disease states are currently being sought.
Longitudinal Analysis of MART‐1/HLA‐A2‐Reactive T Cells Over the Course of Melanoma Progression
Authors: Terheyden P. , Schrama D. , Pedersen L. Ø. , Andersen M. H. , Kämpgen E. , Thor Straten P. , Becker J. C.
Published: November 2003

An HLA‐A2‐positive patient with advanced stage IV melanoma was vaccinated with dendritic cells (DCs) pulsed with melanoma antigens, whereby the rapid progression of disease stalled for a period of 10 months. Monitoring of the cellular immune response against one of the vaccinated HLA‐A2‐restricted epitopes demonstrated both induction and subsequent decline in the number of interferon‐γ (IFN‐γ)‐producing MART‐1‐reactive cells present in the blood. Enumeration of reactive T cells by MART‐126‐35/HLA‐A2 tetramer staining revealed an induction of such cells after three vaccinations and a subsequent decline that most prominent at times of rapid disease progression. However, a substantial number of reactive cells were present even when no MART‐1 reactivity was detectable by functional assays. Isolation of such MART‐126−35‐reactive T cells by means of peptide/HLA‐A2‐coated magnetic beads demonstrated the persistence of a TCRVβ14+ T‐cell clone in this population over the whole observation period. Intracellular fluorescence‐activated cell sorter staining of such TCRVβ14+ T cells for IFN‐γ and interleukin‐2 after maximal stimulation with phorbol 12‐myristate 13‐acetate/ionomycin revealed an impairment in their capacity to produce cytokines at the end of the observation period. Thus, functional changes of individual T‐cell clones, e.g. clonal exhaustion, seem to be responsible for the known discrepancy between functional and phenotype assays for immune monitoring of tumour patients.
Ontogeny of Complement Regulatory Proteins – Concentrations of Factor H, Factor I, C4b‐Binding Protein, Properdin and Vitronectin in Healthy Children of Different Ages and in Adults
Authors: De Paula P. F. , Barbosa J. E. , Junior P. R. , Ferriani V. P. L. , Latorre M. R. D. O. , Nudelman V. , Isaac L.
Published: November 2003

Previous studies of human in vivo complement protein levels have only compared data for neonates with that from adult sera. Here, we establish the normal concentration ranges of the following complement regulatory proteins in healthy Brazilian children of different age groups (neonates: 1 month−1 year, 1–6 years and 6–13 years) and in adults: factor H (fH), factor I (fI), C4b‐binding protein (C4 BP), properdin and vitronectin. We found that the concentrations of fH, fI, properdin and vitronectin in neonates are significantly lower than in adults. Remarkably, the concentration of C4 BP is below the method resolution (<50 µg/ml) in 76% of the sera from neonates, while adults presented 199–532 µg/ml of C4 BP in their sera. The concentration of properdin in the sera from neonates and up to 1‐year‐old children was less than that observed in older children. Adults presented vitronectin levels significantly higher than all the other age groups in the study. No significant sex differences in the concentrations of all the studied regulatory proteins were detected. This study reveals the ontogeny of complement system in greater detail than previously available and may point to the reasons why neonates have higher susceptibility to develop life‐threatening pyogenic infections. These reference values will be of use in clinical and laboratory investigations of disorders associated with low levels of these regulatory proteins.
Nitric Oxide Produced by Murine Dendritic Cells is Cytotoxic for Intracellular Salmonella enterica sv. Typhimurium
Authors: Eriksson S. , Chambers B. J. , Rhen M.
Published: November 2003

The pathogenicity of Salmonella enterica serovar Typhimurium has traditionally been correlated with its ability to survive and grow in macrophages. Macrophage‐derived production of nitric oxide (NO) has been implicated as a major innate defence, restricting bacterial proliferation both in macrophage cultures and in mice. In the present study, we show that the ability of primary murine dendritic cells (DCs) to ingest Salmonella is low, but greatly enhanced by serum complement. Ingestion of bacteria was followed by the expression of inducible nitric oxide synthase (iNOS), as well as by NO production. iNOS mRNA was detected as early as 6 h post infection and production of NO 12 h post infection, rising further at 16 h post infection. Inhibition of the iNOS activity with the inhibitor N‐monomethyl‐l‐arginine or using DCs from iNOS–/– mice resulted in increased intracellular bacterial yields. To further define the potential defensive role of DC‐derived NO, the actual intracellular replication rate of S. Typhimurium in DCs was measured. DC‐derived NO was shown to exert a bactericidal effect, whereas the effect of NO in macrophage‐like J774‐A.1 cells was found to be bacteriostatic. These results identified an important role for NO in restricting S. Typhimurium survival in DCs, indicating that DCs may actively participate in the innate defence against intracellular pathogens.
A Protocol for Generation of Clinical Grade mRNA‐Transfected Monocyte‐Derived Dendritic Cells for Cancer Vaccines
Authors: Mu L. J. , Gaudernack G. , Sæbøe‐Larssen S. , Hammerstad H. , Tierens A. , Kvalheim G.
Published: November 2003

With the aim of producing large quantities of mRNA‐transfected monocyte‐derived dendritic cells (DCs) to be used as cancer vaccines, a new clinical grade procedure has been developed. Peripheral blood mononuclear cells (PBMCs) obtained by leukapheresis were enriched for monocytes by immunomagnetic depletion of CD19+ B cells and CD2+ T cells employing the ISOLEX 300i device. After 5 days of culture of enriched monocytes in gas permeable Teflon bags, using serum‐free medium supplemented with granulocyte/macrophage‐colony stimulating factor and interleukin‐4 (IL‐4), immature DCs were generated. Following transfection with mRNA from three human prostate cancer cell lines (DU145, LNCaP and PC‐3), employing a newly developed square wave electroporation procedure, the immature DCs were immediately transferred to Teflon bags and matured for 48 h, using serum‐free medium supplemented with IL‐1α, IL‐6, tumour necrosis factor‐α and PGE2. The electroporation procedure efficiently transferred mRNA into the DCs with minor effect on the viability of the cells. The generated matured transfected DCs show high expression of the antigens CD83, CD80, CD86 and human leucocyte antigen‐DR. Freezing and thawing of the transfected matured DCs had minor effect on cell viability and the phenotype. From 4 × 109 PBMCs, about 1 × 108 transfected matured DCs are produced. The thawed transfected DCs were able to elicit primary T‐cell responses in vitro against antigens encoded by the prostate cancer mRNA as shown by enzyme‐linked immunospot assay using mock‐transfected DCs as control. Based on these results, clinical trials in cancer patients have been initiated.
B‐Cell Epitopes in the Immunodominant p34 Antigen ofMycobacterium aviumssp.paratuberculosisRecognized by Antibodies from Infected Cattle
Authors: Ostrowski M. , Mundo S. L. , Harris N. B. , Barletta R. G. , Lopez O. J.
Published: November 2003

Mycobacterium aviumssp.paratuberculosis(M. paratuberculosis) causes Johne's disease, a chronic and fatal enteritis in ruminants. In the last stage of the disease, antibody titres rise and levels of interferon‐γ decrease, suggesting that the host–immune response is switching from a T helper 1 (Th1) to a Th2 profile. In infected cattle, the membrane protein p34 elicits the predominant humoral response againstM. paratuberculosis. To map the B‐cell epitopes of this antigen, affinity‐purified bovine antibodies against the carboxy‐terminal region of p34 were used to screen a 12‐mer phage display library. Several phage clones carrying peptides resembling fragments of p34 were affinity selected. Based on the predicted amino acid sequence, peptides were chemically synthesized, which demonstrated reactivity with serum from naturally infected and p34‐vaccinated cattle. Immunization of mice with these peptides elicited an anti‐p34 antibody response. Two B‐cell epitopes were identified and characterized. Based on the reactivity and the type of immune response elicited, epitope A was determined to be conformational, whereas epitope B was demonstrated to be sequential. Both epitopes were shown to be present in p34 proteins fromM. aviumssp.aviumorM. paratuberculosisbut absent fromM. intracellulare, the other member of theM. aviumcomplex. Furthermore, both epitopes were mapped to regions of p34 that display high variability when compared to homologous proteins from other mycobacterial species of public and animal health importance. We hypothesize that these variable regions of p34 may play a role in the immunobiology ofM. paratuberculosisinfections.
Long‐Term Evaluation of a Rat Model of Chronic Cholangitis Resembling Human Primary Sclerosing Cholangitis
Authors: Goetz M. , Lehr H. A. , Neurath M. F. , Galle P. R. , Orth T.
Published: November 2003

Primary sclerosing cholangitis (PSC) is a chronic cholestatic disorder with a presumed autoimmune aetiopathogenesis. We have recently described a novel organ‐specific rat model of fibrosing cholangitis induced by intrabiliary administration of the hapten‐reagent 2,4,6‐trinitrobenzenesulfonic acid (TNBS) with similarities to human PSC. In the present report, we have evaluated the long‐term outcome of TNBS‐induced cholangitis in this model. Mild stenosis of the common bile duct of female Lewis rats (n = 18) was achieved by subtotal ligation and cholangitis induced by TNBS injection (50 mg/kg) into the dilated bile duct after a second laparotomy. After 8 and 12 months, we found no evidence of cholangitis in serum chemistry or histology or retrograde cholangiography of TNBS‐treated rats. Antineutrophil cytoplasmic antibodies were positive in 75% of animals but were not predictive of liver damage. Tumour necrosis factor‐α levels were not elevated in serum or in mononuclear spleen cell supernatants. Our findings suggest that a single initial insult is not sufficient to trigger chronic progressive inflammation. Rather, perpetuation of inflammation probably requires additional stimuli.
Adjuvant Activity of Free Bordetella Pertussis Filamentous Haemagglutinin Delivered by Mucosal Routes
Authors: Poulain‐Godefroy O. , Menozzi F. D. , Alonso S. , Vendeville C. , Capron A. , Locht C. , Riveau G.
Published: November 2003

The development of safe and potent mucosal adjuvants remains a major objective in vaccinology. The potential usefulness of filamentous haemagglutinin (FHA) of Bordetella pertussis as an adjuvant was assessed in a mouse model. The glutathione‐S‐transferase of Schistosoma mansoni (Sm28GST) was used for intranasal administration, while the gut‐resistant keyhole limpet haemocyanin (KLH) was administrated by the oral route. For both antigens, coadministration with FHA increased antigen‐specific immunoglobulin titres. This adjuvant effect did not require chemical cross‐linking or direct interaction between FHA and the antigen tested. FHA also behaved as an adjuvant by the subcutaneous route, indicating that its adjuvanticity is not restricted to binding to mucosal surfaces. The FHA‐induced adjuvanticity was also observed in mice with high anti‐FHA antibody titres as a result of antipertussis vaccination, indicating that pre‐existing anti‐FHA antibodies do not impair FHA adjuvanticity. No mRNA coding for proinflammatory cytokines was induced in the lungs after intranasal FHA administration. However, an increase in the levels of mRNAs coding for B7‐1, transforming growth factor (TGF)‐β and major histocompatibility complex (MHC)‐II was detected in the lungs after FHA administration. Although the molecular mechanisms of the FHA‐induced adjuvanticity remain to be elucidated, the data presented here indicate that this adhesin, already assessed for human use as a pertussis vaccine constituent, represents a promising adjuvant to improve the humoral immune response when given by mucosal routes.
Long‐Term Proliferation and Survival of In Vitro‐Activated T Cells is Dependent on Interleukin‐2 Receptor Signalling but not on the High‐Affinity IL‐2R
Authors: Hedfors I. A. , Brinchmann J. E.
Published: November 2003

Optimization of T‐cell‐activation protocols is an important prerequisite for the use of populations of activated, polyclonal T cells for immunotherapeutic purposes. This study compares two activation protocols. Following initial CD3/CD28 activation, naïve and memory subsets of CD8+ and CD4+ T cells were either repeatedly stimulated or maintained in medium containing interleukin‐2 (IL‐2). Initially, activation‐induced cell death (AICD) was observed in all subsets. After 2–3 days, death in the cultures maintained in IL‐2 only dropped dramatically, while live cells increased logarithmically. Despite intense proliferation, these cells lost the expression of CD25, the α chain of the IL‐2 receptor and CD71, the transferrin receptor. Functional blocking of CD25 caused minimal changes in proliferation and survival of these cells as long as IL‐2 was present in the medium. Blocking of CD25 in combination with the removal of IL‐2 caused rapid death of these cells. Restimulation every 3–4 days led to persistently high levels of AICD and lower live cell counts. Live cells maintained the expression of activation markers and a blastoid phenotype. Initial CD3/CD28 followed by maintenance in IL‐2 for 2–3 weeks seems to be the best in vitro T‐cell‐activation strategy. Signalling through the IL‐2 receptor is vital for these cells, despite their downregulation of CD25.
Biochemical Changes Contributing to Functional Quiescence in Lacrimal Gland Acinar Cells after Chronic Ex Vivo Exposure to a Muscarinic Agonist
Authors: Qian L. , Wang Y. , Xie J. , Rose C. M. , Yang T. , Nakamura T. , Sandberg M. , Zeng H. , Schechter J. E. , Chow R. H. , Hamm‐Alvarez S. F. , Mircheff A. K.
Published: November 2003

Profound secretory dysfunction can be associated with relatively modest lymphocytic infiltration of the lacrimal and salivary glands of Sjögren's syndrome (SjS) patients. SjS patients' sera contain autoantibodies to M3 muscarinic acetylcholine receptors (MAChR) that have variously been reported to have agonistic and antagonistic effects. We sought to identify consequences of chronic agonist stimulation by maintaining acinar cells from rabbit lacrimal glands for 20 h in the presence or absence of 10 µm carbachol (CCh). Exposure to CCh diminished the cells' ability to elevate cytosolic Ca2+ and secrete β‐hexosaminidase in response to acute stimulation with 100 µm CCh, but it enhanced their secretory responses to phenylephrine and ionomycin. Secretory vesicles appeared normal by electron microscopy, but confocal fluorescence microscopy revealed depletion of the secretory vesicle membrane marker, rab3D, and decreased ability to recruit secretory transport vesicles in response to acute 100 µm CCh. Additionally, the apical cortical actin cytoskeleton was disrupted and diminished compared to the basal–lateral cortical network. Subcellular fractionation analyses revealed that total membrane phase protein content was increased. The contents of β‐hexosaminidase and MAChR relative to total protein were not significantly altered, and MAChR abundance in the plasma membrane fraction was increased as the result of redistribution from endomembrane pools. However, relative cellular contents of the heterotrimeric guanosine triphosphate (GTP)‐binding proteins, Gq and G11, were decreased. Additional biochemical changes included decreased contents of 47 kDa Gs and Gi3, protein kinase Cα and rab3D and polymeric immunoglobulin (Ig) receptors; internalization of Na,K‐ATPase from the plasma membranes to endomembrane compartments and decreased content of β‐hexosaminidase in the lysosomes. The observations demonstrate that chronic exposure to a MAChR agonist induces refractoriness to optimal stimulation, without causing receptor downregulation, by downregulating postreceptor‐signalling mediators and effectors. The cells' secretory mechanisms for IgA and electrolytes also appear to be impaired, as does their ability to properly sort proteins to the lysosomes.
Turbidite and contourite sediment waves in the northern Rockall Trough, North Atlantic Ocean
Authors: HOWE JOHN A.
Published: November 2003

Two sediment wave fields have been identified in the northern Rockall Trough; one from the north‐eastern part of the trough, developed on the flank of an elongate sediment drift, and the other at the distal edge of the Barra Fan. Wavelengths in both areas vary from 1 to 2 km and wave heights from 5 to 20 m. The seismic character of both the wave fields is similar with a lower package of well‐layered, medium‐ to high‐intensity reflectors migrating upslope, overlain by a dominantly acoustically transparent unit containing irregular, semicontinuous reflectors. Eight cores have been recovered from the two wave fields, seven from the crest‐trough areas of the distal Barra Fan wave field, and a single core from the crest of the sediment‐drift waves. Lithologically, the cores show that different processes have been active across the two wave fields. Cores from the Barra Fan field contain thin turbidites with thicker, draped hemipelagites and hemiturbidites, corresponding to the well‐layered, reflective seismic units and transparent seismic unit, respectively. These waves have been maintained by turbidity currents, perhaps over older, originally bottom‐current‐formed waves. The single core from the small sediment‐drift wave field recovered hemipelagites and glaciomarine sediments grading upwards into muddy‐silty contourite deposits, topped by a sandy contourite. These waves were constructed by contour currents. Dating of cores from these two small wave fields revealed that the sequences of thin turbidite and hemipelagite sediments from the Barra Fan correspond to the Late Glacial‐Allerød/Bölling Interstadial with the overlying hemipelagite of Younger Dryas‐Holocene age. The contourite deposits from the north‐east Rockall Trough wave field have been dated as early Holocene, reflecting increasing bottom‐current activity at the changeover from a glacial to an interglacial regime.
Carbonate petrography as an indicator of climate and sea‐level changes: new data from Bahamian Quaternary units
Authors: KINDLER PASCAL , HEARTY PAUL J.
Published: November 2003

Coeval stratigraphic units of similar petrology occur throughout the northern Bahamas islands. The petrographic composition of these limestones provides clues about regional sea level and climate changes during the late Quaternary. At least eight fossil shoreline units, which are linked to transgressive episodes between the middle Pleistocene and the late Holocene, are recognized in the Bahamas. The petrographic composition of these units is either dominated by ooids and peloids or by bioclasts. Sedimentological observations demonstrate that oolitic‐peloidal units were formed when sea level was higher than today, whereas skeletal units were deposited at or below modern ordnance datum. Skeletal units may reflect times of partial, or modest platform flooding, when the bulk of sediments brought to islands originates from bank‐margin reefs. In contrast, oolitic‐peloidal units correspond to major flooding events and active water circulation on the bank top. Cement fabrics further show that the early diagenesis of oolitic units took place during warm and humid climatic conditions, whereas skeletal rock bodies underwent subaerial diagenesis during drier climatic conditions characterized by marked seasonal changes. This example from the Bahamas suggests that compositional analysis of limestone from fossil carbonate platforms could be used for resolving ancient climate and sea‐level changes.
Cross‐platform architecture of a sequence boundary in mixed siliciclastic‐carbonate lithofacies, Middle Cambrian, southern Great Basin, USA
Authors: OSLEGER DAVID A. , MONTAÑEZ ISABEL P.
Published: November 2003

Stratigraphic analysis of mixed siliciclastic‐carbonate lithofacies within the Middle Cambrian Bonanza King Formation of the southern Great Basin reveals three distinct facies associations that record a range of depositional environments from semi‐arid tidal flats to deeper subtidal, restricted lagoons. Stratigraphic trends, cross‐platform facies variations and correlation of individual surfaces across 250 km of the study area suggest that these mixed lithofacies were deposited in three temporally distinct phases. (1) Extensive progradation of mixed peritidal environments culminated in a prolonged episode of subaerial exposure marked by an areally extensive intraclast breccia (0·5–1·2 m thick) that we interpret to be a major Type 1 sequence‐bounding disconformity. (2) Abrupt flooding of the exposed platform resulted in the deposition of mixed deeper subtidal lithofacies, including a condensed interval of fissile, fossiliferous shale. (3) Progressive shallowing and aggradational accumulation was accompanied by a decrease in siliciclastics and a shift to pure carbonate deposition. Deep‐water siliciclastics and megabreccias record deposition along the base‐of‐slope off the Middle Cambrian shelf‐edge, and are interpreted to represent lowstand deposits emplaced during the prolonged episode of subaerial exposure of the shallow shelf.

The presence of fine siliciclastics in both peritidal facies and sharply overlying deeper subtidal facies of the study interval within the Bonanza King suggests a variable, but relatively continuous, influx of terrigenous material throughout an extended period of accommodation change, apparently asynchronous with respect to the predictive model of reciprocal sedimentation. We suggest that the primary siliciclastic source changed with relative sea‐level position. During lowered sea level, aeolian processes acting upon the unvegetated Cambrian craton transported fine siliciclastics onto peritidal and shallow‐subtidal environments. During higher sea level, coastal siliciclastic reservoirs supplied sediment that was transported for long distances by geostrophic currents flowing along the submerged platform.

As opposed to many Cambro‐Ordovician grand cycles that are commonly interpreted to consist of a transgressive shaly half‐cycle grading upward into a regressive carbonate half‐cycle, the sequence boundary within this Middle Cambrian succession occurs within siliciclastic‐rich, mixed lithofacies rather than in adjoining purer carbonates, implying that some ‘grand cycles’ should not be considered synonymous with ‘sequences’. Interbasinal correlations of the Type 1 sequence boundary within the mixed unit are speculative, primarily because of the inherent imprecision of available trilobite biostratigraphy. However, there is evidence that an extended episode of subaerial exposure may have been continent‐wide during the Ehmaniella trilobite biochron.
Origin and significance of mud‐filled incised valleys (Upper Cretaceous) in southern Alberta, Canada
Authors: EBERTH DAVID A.
Published: November 2003

Seven mud‐filled incised valleys (MFIVs) in the paralic facies of the Dinosaur Park and Horseshoe Canyon formations (Upper Cretaceous) of southern Alberta were studied to better understand their morphology, geometry and depositional histories in an estuarine context. Two preservational geometries occur: simple, U‐shaped forms; and internally complex forms. Both types of MFIV record deposition in the central zone of low energy (turbidity) in an estuarine setting.

Simple, U‐shaped MFIVs have sharp basal erosional surfaces and consist of mudstone‐dominated heterolithic fills of channel‐wide, concave‐up laminae. Associated fossil assemblages are marine to brackish. Each simple MFIV records a cut‐and‐fill history associated with a cycle of relative sea‐level drop and rise. Low‐energy depositional settings, loss of channel form during infilling, and associated shoreface deposits, as well as the absence of clear tidal indicators suggest a coastal plain estuarine setting, along a wave‐dominated, barred coastline.

Complex MFIVs are rarer, and consist of imbricated, wedge‐shaped sets of inclined‐to‐horizontal heterolithic strata. Tidal deposits and/or nonmarine‐to‐marine macrofossils occur locally. Complex MFIVs were infilled in meandering reaches of the central zone of low energy in tide‐dominated estuaries. Their rarity compared to simple MFIVs and their freshwater palaeontological content suggest that they were contiguous landward with extensive fluvial channels. A complex MFIV near Onefour comprises three in‐channel depositional cycles. Each cycle consists of an erosional surface overlain by lateral accretion bedding and a conformable transition to vertically aggraded strata. Each cycle reflects a cut‐and‐fill event under the control of changes in relative sea‐level that culminated in overbank flooding.

All MFIVs formed in low‐gradient settings (≤0.03%) where estuarine zones were stretched out over many tens of kilometres. Tide‐dominated estuaries apparently exhibited simple, straight‐to‐meandering upstream transitions and extensive landward penetration (≥200 km) of tidal backwater effects. Few modern estuaries serve as adequate modern analogues to these ancient, tide‐dominated estuaries.

Radiometric data indicate that MFIV cut‐and‐fill cycles were 100 000‐400 000 years in maximum duration and thus, equivalent to 4th order sea‐level cycles. However, negative evidence tentatively suggests that these cycles took place over time intervals 1‐2 orders of magnitude smaller (5th order or higher sea‐level cycles).
The morphological dynamics of intertidal megaripples in the Mawddach Estuary, North Wales, and the implications for palaeoflow reconstructions
Authors: LARCOMBE PIERS , JAGO COLIN F.
Published: November 2003

The morphology and migration rate of tidal bedforms are important because of their use in interpretation of modern and ancient sediment transport regimes. Tidal flow, megaripple morphology and migration were studied in the mesotidal Mawddach Estuary, North Wales, to examine the veracity of published flow‐bedform relationships, quantify spatial variations in migration and assess consequences for palaeoflow reconstruction. Two transects were surveyed along a megarippled intertidal shoal (mean grain size 280 μm) for a period of 22 semi‐diurnal tidal cycles. A vertical array of current meters recorded tidal current profiles at the centre of one of the transects.

Flood tidal currents dominate at Fegla Fach shoal, with peak velocities over 1 m s−1 at spring tides, and 0.5 m s −1 at neaps, and bed sediment transport was also flood‐dominated. Over the lunar cycle, the morphology of the megaripples on the survey lines was divisible into three phases:

1 the neap mode‐consisting of near‐moribund two‐dimensional (2‐D) flood‐orientated megaripples of wavelength c. 6 m and height c. 0.2 m;

2 a transitional mode‐where, on rising tidal ranges, scour pits formed and developed into 3‐D megaripples which underwent net migration with the flood tide;

3 the spring mode‐consisting of 3‐D megaripples of wavelength c. 4 m and height c. 0.2 m. Despite complete re‐orientation by the ebb tide, these were recognizable from one low water survey to the next, and net migration was c. 1 m per tide with the flood tide. We infer the presence of the equilibrium ‘spring tidal form’ occurring as flood‐orientated megaripples during the flood tide.

The data support previously reported separation of 2‐D and 3‐D megaripples at a depth to grain size ratio of 8000, and at a depth‐mean velocity of the dominant tide (Umaxdom) of 0.75‐0.8 m s−1. A migration threshold exists at Umaxdom of c. 0.53‐0.57 m s−1.

Measures of migration which might be used on preserved sections have been applied to the data. These measures systematically overestimated bedform migration at most stages of the lunar cycle (by <25% at spring tides and <140% in the post‐spring transition period), but were accurate when the megaripples had developed into their 'spring tidal form’. There is significant variation of migration rates within the survey populations. We conclude that whilst the occurrence of megaripple cross‐sets may be used as a palaeoflow indicator, and sedimentary structures associated with 2‐D to 3‐D transitions may also be indicative of palaeoflows, there are likely to be significant uncertainties involved in using tidal bundles as an indication of sediment transport rates.
Geostrophic sand ridge, dune fields and associated bedforms from the Northern KwaZulu‐Natal shelf, south‐east Africa
Authors: RAMSAY PETER J. , SMITH ALAN M. , MASON THOMAS R.
Published: November 2003

Subaqueous dunes are formed on the KwaZulu‐Natal outer‐shelf due to sediment transport by the Agulhas Current (geostrophic current). These dunes occur within two dune fields at depths of − 35 to − 70 m. The net sediment transport direction is south, but short‐period reversals form northward‐migrating bedforms. The dune fields are physically bounded by late Pleistocene beachrock and aeolianite ledges. A bedform hierarchy has been recognized in the dune fields comprising a system of three generations of climbing bedforms. The outer dunefield has given rise to a sand ridge (H=12 m; L=4 km; W=1.1 km; and an 8° lee slope) whereas the inner dune fields have achieved large‐scale dune status. Bedload parting zones within the dune fields occur where the sediment transport direction switches from north to south due to reversals in the geostrophic flow; these zones occur at depths of − 60, − 47 and − 45 m. An interpretative stratigraphic model is presented on what such geostrophite deposits would look like in the ancient sedimentary record.
Frequency spectra and intermittency of the turbulent suspension process in a sand‐bed river
Authors: LAPOINTE MICHEL F.
Published: November 2003

Previous research suggests that the turbulence‐driven suspension process in sand‐bed channels is dominated by intermittent, energetic eddies with length scales of the order of channel depth. Because of the scarcity of data on the turbulent suspension process in alluvial channels, the possible variability in suspension intermittency and turbulent frequency content due to contrasts in flow depth, velocity or bedforms remains unclear however. The present study analyses eddy correlation suspension signals from seven deployments in varied flow conditions around a sandy meander bend. Deployment depths at near‐bankfull flow stages varied from 2 to 5.5 m, velocities at 0.75–1 m height from 0.6 to 0.9 m s−1 and local mean suspended sand concentrations ranged from 30 to 150 mg L−1 in the intermittence and spectral content of sand suspension between the various deployments are analysed and results are compared with previously published findings. Study data suggest that the dominant eddy sizes involved in sediment mixing across the sensor level are consistently of the order of 1–5 times flow depth and lie within the ‘energy‐bearing’ turbulent range. When sand suspension is analysed in the time domain in the various deployments, energetic, burst‐like suspension events occupying only 1‐5% of the record duration account for 20‐90% of the suspension work. The degree of intermittence in the suspension process was observed to increase in deeper flows, where mixing events contributing extreme vertical sediment fluxes appear to be relatively more frequent.
An interplay of syn‐ and intereruption depositional processes: the lower part of the Jangki Group (Miocene), SE Korea
Authors: BAHK J. J. , CHOUGH S. K.
Published: November 2003

The lower part of the Jangki Group (Miocene), SE Korea consists of pyroclastic mass‐flow‐dominated facies and epiclastic stream‐flow‐dominated facies which reflect sedimentation during syn‐ and intereruption periods, respectively. On the basis of pyroclastic composition, sedimentary structures and bed geometry, they are organized into two facies associations: (1) dacitic and basaltic debris‐flow and hyperconcentrated‐flood‐flow deposits of eruption periods, and (2) epiclastic stream‐flow and interchannel deposits of intereruption periods. The lateral relationship between the syn‐ and intereruption deposits varies significantly over short distances (2 km). In the western part of the study area, syneruption deposits are predominant, and fluvial deposits occur as small‐scale channel‐fill gravelstone bodies encased within dacitic debris flow deposits. In the eastern part, however, intereruption deposits are dominated with thick sequences of interbedded channel and interchannel deposits. The abrupt lateral change indicates alternation of epiclastic axial fluvial system with pyroclastic‐rich volcaniclastic aprons. The syneruption deposits are enriched in vitric ash but lack contemporary volcanic rock fragments (dacitic or basaltic). They are sharply differentiated from intereruption deposits that mostly consist of epiclasts and are deficient in vitric ash. The vertical transition suggests that streams drained a hinterland of igneous basement rocks during intereruption periods and became bulked with pyroclasts during syneruption periods.