bluuebunny/crossref_metadata_2025_split huggingface dataset:
Signalling events involved in interferon‐γ‐inducible macrophage nitric oxide generation
Authors: Blanchette Julie , Jaramillo Maritza , Olivier Martin 
Published: December 2004

SummaryNitric oxide (NO) produced by macrophages (Mφ) in response to interferon‐γ (IFN‐γ) plays a pivotal role in the control of intracellular pathogens. Current knowledge of the specific biochemical cascades involved in this IFN‐γ‐inducible Mφ function is still limited. In the present study, we evaluated the participation of various second messengers – Janus kinase 2 (JAK2), signal transducer and activator of transcription (STAT) 1α, MAP kinase kinase (MEK1/2), extracellular signal‐regulated kinases 1 and 2 (Erk1/Erk2) and nuclear factor kappa B (NF‐κB) – in the regulation of NO production by IFN‐γ‐stimulated J774 murine Mφ. The use of specific signalling inhibitors permitted us to establish that JAK2/STAT1α‐ and Erk1/Erk2‐dependent pathways are the main players in IFN‐γ‐inducible Mφ NO generation. To determine whether the inhibitory effect was taking place at the pre‐ and/or post‐transcriptional level, we evaluated the effect of each antagonist on inducible nitric oxide synthase (iNOS) gene and protein expression, and on the capacity of IFN‐γ to induce JAK2, Erk1/Erk2 and STAT1α phosphorylation. All downregulatory effects occurred at the pretranscriptional level, except for NF‐κB, which seems to exert its role in NO production through an iNOS‐independent event. In addition, electrophoretic mobility shift assay (EMSA) analysis revealed that STAT1α is essential for IFN‐γ‐inducible iNOS expression and NO production, whereas the contribution of NF‐κB to this cellular regulation seems to be minimal. Moreover, our data suggest that Erk1/Erk2 are responsible for STAT1α Ser727 residue phosphorylation in IFN‐γ‐stimulated Mφ, thus contributing to the full activation of STAT1α. Taken together, our results indicate that JAK2, MEK1/2, Erk1/Erk2 and STAT1α are key players in the IFN‐γ‐inducible generation of NO by Mφ.
Induction of apoptosis in monocytes by Mycobacterium leprae in vitro: a possible role for tumour necrosis factor‐α
Authors: Hernandez M. O. , Neves I. , Sales J. S. , Carvalho D. S. , Sarno E. N. , Sampaio E. P. 
Published: December 2004

SummaryA diverse range of infectious organisms, including mycobacteria, have been reported to induce cell death in vivo and in vitro. Although morphological features of apoptosis have been identified in leprosy lesions, it has not yet been determined whether Mycobacterium leprae modulates programmed cell death. For that purpose, peripheral blood mononuclear cells obtained from leprosy patients were stimulated with different concentrations of this pathogen. Following analysis by flow cytometry on 7AAD/CD14+ cells, it was observed that M. leprae induced apoptosis of monocyte‐derived macrophages in a dose‐dependent manner in both leprosy patients and healthy individuals, but still with lower efficiency as compared to M. tuberculosis. Expression of tumour necrosis factor‐α (TNF‐α), Bax‐α, Bak mRNA and TNF‐α protein was also detected in these cultures; in addition, an enhancement in the rate of apoptotic cells (and of TNF‐α release) was noted when interferon‐γ was added to the wells. On the other hand, incubation of the cells with pentoxifylline impaired mycobacterium‐induced cell death, the secretion of TNF‐α, and gene expression in vitro. In addition, diminished bacterial entry decreased both TNF‐α levels and the death of CD14+ cells, albeit to a different extent. When investigating leprosy reactions, an enhanced rate of spontaneous apoptosis was detected as compared to the unreactive lepromatous patients. The results demonstrated that M. leprae can lead to apoptosis of macrophages through a mechanism that could be at least partially related to the expression of pro‐apoptotic members of the Bcl‐2 protein family and of TNF‐α. Moreover, while phagocytosis may be necessary, it seems not to be crucial to the induction of cell death by the mycobacteria.
A potent adjuvant effect of CD40 antibody attached to antigen
Authors: Barr Tom A. , Mccormick Adele L. , Carlring Jennifer , Heath Andrew W. 
Published: December 2004

SummaryThere is great potential for novel vaccines based on recombinant proteins and synthetic peptides. Unfortunately these antigens often lack the immunogenicity of whole, killed pathogens used in traditional vaccines. Thus there is strong interest in the identification of immunological adjuvants with low reactogenicity, but high potency, to enhance immune responses and realize the potential of these new vaccine strategies. CD40 antibodies have been shown to have adjuvant effects when administered at very high doses. These large doses are impractical and induce a cascade of cytokine release giving rise to septic shock‐like symptoms, as well as splenomegaly and polyclonal antibody production. We show here that a very small amount of CD40 antibody can exhibit potent adjuvant effects when attached to soluble antigen. The lack of detectable systemic effects indicates that this method may be a powerful and practical means of enhancing the efficacy of recombinant vaccines.
Mycophenolic acid is a potent inhibitor of the expression of tumour necrosis factor‐ and tumour necrosis factor‐receptor superfamily costimulatory molecules
Authors: Van Rijen Miranda M. L. , Metselaar Herold J. , Hommes Martijn , Ijzermans Jan N. M. , Tilanus Hugo W. , Kwekkeboom Jaap 
Published: December 2004

SummaryThe tumour necrosis factor (TNF) ligands CD154, CD70 and TNF receptors CD134 and CD137 are all involved in allograft rejection. Because these molecules are not present on resting T cells, we investigated whether immunosuppressive drugs could inhibit their induction. Expression was induced in vitro on T cells by phorbol 12‐myristate 13‐acetate and ionomycin or by allogeneic dendritic cells in the presence or absence of cyclosporin A (CsA), tacrolimus (TAC), rapamycin derivative (SDZ RAD), or mycophenolic acid (MPA), and determined by flow cytometry. To study the effect of in vivo exposure to immunosuppressive drugs on these molecules, immunohistochemistry was performed on human lymph nodes from patients treated with TAC or TAC and MMF. The calcineurin inhibitors (CI) CsA and TAC strongly suppressed the induction of CD70, CD137 and CD154, but not of CD134, upon pharmacological stimulation of T cells in vitro. In allogeneic stimulations only CD137 and CD154 were inhibited by CI. SDZ RAD did not inhibit pharmacological induction, but in allogeneic stimulations all the investigated molecules were partially suppressed. Both in pharmacological and in allogeneic stimulations, MPA inhibited induction of all tested molecules on T cells nearly completely at 4 µg/ml. However, in lymph nodes obtained from patients chronically treated with MMF and TAC no reduction of the expression of these molecules was observed. This was possibly caused by trough levels which were in vivo lower (mean: 2·3 µg/ml) than the concentration giving complete inhibition in vitro. In conclusion, in contrast to CsA, TAC and SDZ RAD, MPA is a potent inhibitor of the induction of TNF‐ and TNF‐receptor superfamily molecules on T cells. To obtain long‐term suppression of these molecules in vivo, a plasma trough level of 4 µg/ml is indicated.
Peptide‐based analysis of the amino acid sequence important to the immunoregulatory function of Trypanosoma cruzi Tc52 virulence factor
Authors: Borges Margarida , Da Silva Anabela Cordeiro , Sereno Denis , Ouaissi Ali 
Published: December 2004

SummaryThe intracellular protozoan parasite Trypanosoma cruzi is the aetiological agent of Chagas' disease. We have previously identified a T. cruzi‐released protein called Tc52, which is crucial for parasite survival and virulence. In the present study, we attempted to define the Tc52 epitope(s) responsible for its immunoregulatory function. A naturally occurring major peptide fragment of molecular mass 28 kDa (Tc28k) was identified, which was localized in the C‐terminal portion of Tc52 and was inhibitory for T‐cell activation. Synthetic peptides corresponding to amino acid sequences in Tc52 were evaluated for their ability to modulate T‐cell proliferation and cytokine production. Results obtained using five peptides spanning the N‐terminal or C‐terminal domain of the Tc52 protein indicated that the activity mapped to Tc52 residues 432–445. Moreover, it was found that the peptide, when coupled to a carrier protein (ovalbumin), exhibited increased inhibitory activity on T‐lymphocyte activation. Incubation with 8 nm ovalbumin‐coupled peptide 432–445 resulted in approximately the same levels (>75%) of inhibition of T‐cell proliferation as 5 µg/ml Tc28k. Furthermore, we showed that the coupled peptide significantly down‐regulated the secretion of interferon‐γ (IFN‐γ) and interleukin‐2 (IL‐2). Likewise, in immunized mice, the coupled peptide 432–445 was a very poor B‐ and T‐cell antigen compared with the other Tc52‐derived peptides. These results suggest that the immunomodulatory portion of the T. cruzi Tc52 virulent factor may reside, at least in part, in a conserved sequence within its C‐terminal domain, which could minimize its antigenicity.
A differential requirement for phosphoinositide 3‐kinase reveals two pathways for inducible upregulation of major histocompatibility complex class II molecules and CD86 expression by murine B lymphocytes
Authors: Marshall‐Clarke Stuart , Tasker Lynn , Heaton Mark P. , Parkhouse R. Michael E. 
Published: December 2004

SummaryConstitutive expression of major histocompatibility complex class II molecules (MHC II) is restricted to dendritic cells, cells of the macrophage lineage and B lymphocytes. In all three lineages, peptide fragments of captured antigen are loaded into newly synthesized MHC II molecules. In B‐lineage cells, MHC II synthesis is dramatically increased on encounter with antigen, by T‐cell‐derived signals and by microbial products. We have previously shown that immature B cells fail to hyperexpress MHC II after antigen receptor [B‐cell receptor (BCR)] ligation, but are responsive to other stimuli. Expression of the costimulatory molecule, CD86, was similarly regulated. This suggested the existence of two pathways regulating expression of these important molecules. Here we present data supporting this hypothesis. We show that activity of the enzyme phosphatidylinositol 3‐kinase is critical for MHC II hyperexpression and induction of CD86 in response to ligation of the BCR or CD38, but not for responses to other stimuli including interleukin‐4, lipopolysaccharide and CD40 ligation.
Telomere length measurement and determination of immunosenescence‐related markers (CD28, CD45RO, CD45RA, interferon‐γ and interleukin‐4) in skin‐homing T cells expressing the cutaneous lymphocyte antigen: indication of a non‐ageing T‐cell subset
Authors: Neuber Karsten , Schmidt Saskia , Mensch Andrea 
Published: December 2004

SummaryThe purpose of this study was to investigate the immunosenescence of skin‐homing T cells expressing the cutaneous lymphocyte antigen (CLA). Peripheral blood lymphocytes from 72 healthy individuals (33 male and 39 female; median age 54 years; age‐range: 18–94 years) were investigated. The expression of CD28, CD45RA and CD45RO, as well as intracellular interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) formation of CLA+ ‘skin homing’ T cells, was analysed. In addition, T cells were detected immunohistologically in skin specimens from 15 young and 15 old, healthy individuals. The relative telomere length (RTL) was measured by fluorescence in situ hybridization using flow cytometry (flow FISH). The total number of CLA+ T cells was found to remain constant with increasing age. In contrast to peripheral blood T cells (CD3+ CLA−), which showed significantly decreased CD28 and CD45RA expression in donors > 60 years of age, no age‐related alterations of either CD28+ CLA+ T cells or CD45RA+ CLA+ T cells were observed. In the group of donors > 60 years of age, the proportion of intracellular IFN‐γ‐producing CD3+ CLA− cells showed a significant increase, whereas the number of IFN‐γ‐ and IL‐4‐producing CLA+ T cells was not affected by age. After stimulation with phytohaemagglutinin (PHA) or staphylococcal enterotoxin B (SEB), CLA+ T cells from old donors did not show a reduced response compared with CLA+ T cells from young donors. Additionally, the counts of T cells in healthy skin from young and old adults were statistically not different. Furthermore, the RTL was significantly shortened in enriched CD45RO+ CLA− T cells from healthy old individuals, but not in aged CLA+ T cells. The present data suggest that CLA+ T cells might be a T‐cell subpopulation which does not undergo immunosenescence. This may explain why the intensity of inflammatory skin reactions (e.g. psoriasis or eczema) seems to be independent of the patients' age.
Year‐dependent sex‐biased mortality in supplementary‐fed Tengmalm's owl nestlings
Authors: Hipkiss Tim , Hörnfeldt Birger , Eklund Ulf , Berlin Sofia 
Published: December 2004

Summary

In sexually size‐dimorphic birds, the larger sex requires more energy during growth, and often suffers from a higher mortality risk during growth than the smaller one when food is limited.
Sex‐specific growth and mortality were examined in Tengmalm's owl Aegolius funereus (L.) nestlings, a species in which adult females are slightly larger than males. Nestlings were unambiguously sexed using molecular techniques. Nestling mortality in broods provided with supplemental food was compared with that in controls in an experiment carried out during two breeding seasons, 1998 and 1999.
The natural food supply during the two years of the experiment differed. Although the spring vole abundance was similar for the two years, 1998 was characterized by a less severe decline in vole abundance during the previous winter, and also a greater increase in vole abundance during the summer than 1999. It was consequently inferred that the owls’ natural food supply was more limited in 1999.
In 1998, female nestlings attained a 5% higher asymptotic mass than males, and fed nestlings were heavier than controls. No difference in rate of mass gain or wing growth was detected.
Overall mortality was lower in fed broods than controls in 1999 only. Unexpectedly, female nestling mortality was unaffected by supplemental feeding during both years. However, in 1999, when natural food supply was more limited, male nestling mortality was reduced in supplementary‐fed broods.
It is suggested that the females’ larger size gives them a competitive advantage against their male siblings when fighting over food items, and that when food is limited, males rather than females suffer increased mortality owing to lack of food.
This study illustrates the importance of repeating food supplementation experiments to account for annual variation in natural food supply.
The functional response in three species of herbivorous Anatidae: effects of sward height, body mass and bill size
Authors: Durant Daphné , Fritz Hervé , Blais Sandra , Duncan Patrick 
Published: December 2004

Summary

The functional response, i.e. the quantity of food consumed per unit of time as a function of food availability, is a central process in foraging ecology. The application of this concept to foraging by mammalian herbivores has led to major insights into the process of resource acquisition, but it has so far been little used to understand foraging in avian herbivores.
In this study, we describe the functional responses of three grazing Anatidae, the wigeon Anas penelope L. (mean body mass in this study 620 g), the barnacle goose Branta leucopsis B. (2000 g), and the greylag goose Anser anser L. (3500 g). We measured instantaneous intake rates on eight grass heights from 1 cm to 12 cm, as well as pecking rates and peck sizes, and used the Spalinger–Hobbs model developed for mammalian herbivores to explore the mechanisms limiting intake in these three species.
Greylag geese increased their intake rate with increasing food availability (a Type II response), wigeon showed a weak quadratic (Type IV) response, and intake rate by barnacle geese did not vary significantly across the range of variability we offered the birds.
Intake rates differed markedly between individuals, especially in greylag geese, where body mass explained much of the variation. For individuals in all three species, peck sizes strongly influenced instantaneous intake rates, and the size of the bill (width in particular) appeared to be an important determinant of peck size.
Peck sizes increased with sward height (although only very weakly in wigeon), but so did cropping time for wigeon and barnacle geese, which led to a significant decline of intake rates on the tallest grass, at least in the small wigeon. For these very selective small herbivores, the time to crop a mouthful was therefore a significant limiting factor for the birds’ instantaneous intake rate (in addition to peck size and swallowing time). This differs markedly from the situation in mammalian herbivores where bite size (through chewing time) is the principal controlling process in food concentrated patches, a result that we found in greylag geese. We discuss the differences in foraging between the three species in relation to their principal food resources, body mass and bill morphology.
Phenotypic correlates of post‐fledging dispersal in a population of greater flamingos: the importance of body condition
Authors: Barbraud Christophe , Johnson Alan R. , Bertault Guillaume 
Published: December 2004

SummaryFactors influencing post‐fledging movements before the first breeding attempt were studied in individually marked greater flamingos (Phoenicopterus ruber roseus) born in the Camargue, southern France, between their natal area and their principal wintering grounds (Spain, Sardinia, Tunisia and France) from 1995 to 1999.We tested whether post‐fledging dispersal was affected by sex, age, year, body condition, body mass and tarsus length using a multistate capture–recapture modelling approach. We focused particularly on the hypothesis that increased movement probabilities were associated with good and poor body condition. Because long‐distance dispersal is energetically expensive and may involve a high risk of mortality, the acquisition of a robust physical condition prior to dispersal probably plays a critical role in determining the extent to which animals disperse. At the other extreme, birds in poor condition either leave their natal area or starve, which should result in relatively high dispersal rates.Movement probabilities were not sex‐dependent, but were age‐dependent with high movement probabilities during the first year of life (above 0·6) and low probabilities after the first year (0·055). Movement probabilities also differed between years and localities.Movement probability from the natal area was related to the body condition (and body mass) of the fledglings, with a high movement probability (0·873) when juveniles were in good body condition, and a relatively lower probability (from 0·629 to 0·724) when juveniles were in poorer condition. The proportion of variability in dispersal explained by body condition and body mass were 90·9% and 63·5%, respectively.Results support the hypothesis that condition affects dispersal patterns from the natal area. They also suggest that body condition and local environmental conditions during the early growth play a role in dispersal.
Manipulation of offspring number and size: benefits of large body size at birth depend upon the rearing environment
Authors: Oksanen Tuula A. , Jokinen Ilmari , Koskela Esa , Mappes Tapio , Vilpas Heli 
Published: December 2004

Summary

Allocation of reproductive effort between the number and size of offspring determines the immediate rearing environment for the growing young. As the number of offspring increases, the amount of parental investment per individual offspring decreases, and the quality of the rearing environment is expected to decrease. This may result in a lower quality of offspring reared in such conditions.
We studied the effects of the rearing environment on the quality of juvenile bank voles, Clethrionomys glareolus, with different initial body sizes at birth in a 2 × 2 factorial experiment. The rearing environment was manipulated by enlarging both the litter size by two extra pups, and mean offspring body size at birth by replacing the original litter with heavier pups from smaller litters. Offspring quality was estimated from body size measurements, parasitic infection with Eimeria spp. and the level of immune response to a novel antigen.
The analyses revealed that large body size at birth was an advantage in ‘normal’ rearing environments, but a disadvantage in poor ones. The initially normal sized offspring grown in enlarged litters had a relatively good capacity for growth and high immune function confirming that a poor rearing environment alone does not reduce their quality.
Our findings that the benefits of large body size depend on the rearing environment suggest that offspring body size is adjusted in relation to litter size, and thus the evolution of these two traits is combined.
Rodents, cowpox virus and islands: densities, numbers and thresholds
Authors: Begon Michael , Hazel Sarah M. , Telfer Sandra , Bown Kevin , Carslake David , Cavanagh Rachel , Chantrey Julian , Jones Trevor , Bennett Malcolm 
Published: December 2004

SummaryThe population dynamics of bank voles and wood mice, and of cowpox virus infection in these two species, was studied over a 2‐year period in a mainland population and in 14 nearby island populations of varying sizes.For both species, there was no intrinsic variation in the pattern of host dynamics with island size: small island populations behaved as though they were small subsamples of a larger population, displaying no more than the expected random variation from the general pattern.None the less, the relative numbers of bank voles to wood mice increased markedly with decreasing island size; and bank vole densities tended to be higher on smaller islands.Only 22 animals were discovered to have moved either between islands or between the mainland and the islands, out of 1883 captured in all. None the less, it was apparent that males were more likely to move than females.Overall patterns of cowpox virus dynamics were similar in all cases. However, on all islands there were extended periods when cowpox virus infection was apparently absent, and on the small islands the numbers of infected individuals were mostly very low and in many cases infection was never found.For both host species, there was no evidence for a threshold population size for cowpox virus (critical community size) in terms of density, but clear evidence for one in terms of the numerical size of populations. This suggests little support for density‐dependent transmission, despite this having been the usual default assumption for non‐sexually transmitted infections.There was also evidence for a separate invasion threshold (between ecological and epidemiological invasion) and persistence threshold (between epidemiological invasion and persistence). This is contrary to the output of the most‐quoted (deterministic) models – persistence and invasion threshold one and the same – highlighting the fact that little attention has been paid in the past to the practical meaning of the theoretical concept of a threshold.In the case of the wood mice, a superficial similarity to the bank vole thresholds was potentially misleading. Wood mouse thresholds were influenced at least as much by the bank vole thresholds as they were by the dynamics within the wood mouse populations themselves.