bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pre‐assembly of the extracellular domains of CD40 is not necessary for rescue of mouse B cells from anti‐immunoglobulin M‐induced apoptosis
Authors: Ellmark Peter ,   CHRISTINA,   FUREBRING, Borrebaeck Carl A. K. 
Published: December 2004

SummaryCD40 is a tumour necrosis factor receptor (TNFR) family member of central importance for the adaptive immune system. To elucidate the functional role of the different extracellular domains of CD40, we have created a set of truncated CD40 molecules where domains, or parts of domains, have been removed. These CD40 proteins, which contain a peptide tag in the N‐terminal end, have been expressed in a murine B‐cell line, WEHI 231. It was found that ligation of these engineered CD40 proteins via the peptide tag, was sufficient to rescue as well as to promote proliferation of apoptotic WEHI 231 cells, even when all the extracellular domains of CD40 were absent. Our results suggest that pre association of CD40 in the cell membrane plays no critical role for the CD40 signalling pathway. Furthermore, our data imply that conformational changes initiated in the extracellular domains of CD40 are not essential for signal transduction.
Human immunodeficiency virus receptor and coreceptor expression on human uterine epithelial cells: regulation of expression during the menstrual cycle and implications for human immunodeficiency virus infection
Authors: Yeaman Grant R. , Howell Alexandra L. , Weldon Sally , Demian Douglas J. , Collins Jane E. , O'Connell Denise M. , Asin Susana N. , Wira Charles R. , Fanger Michael W. 
Published: December 2004

SummaryHuman immunodeficiency virus‐1 (HIV‐1) is primarily a sexually transmitted disease. Identification of cell populations within the female reproductive tract that are initially infected, and the events involved in transmission of infection to other cells, remain to be established. In this report, we evaluated expression of HIV receptors and coreceptors on epithelial cells in the uterus and found they express several receptors critical for HIV infection including CD4, CXCR4, CCR5 and galactosylceramide (GalC). Moreover, expression of these receptors varied during the menstrual cycle. Expression of CD4 and CCR5 on uterine epithelial cells is high throughout the proliferative phase of the menstrual cycle when blood levels of oestradiol are high. In contrast, CXCR4 expression increased gradually throughout the proliferative phase. During the secretory phase of the cycle when both oestradiol and progesterone are elevated, CD4 and CCR5 expression decreased whereas CXCR4 expression remained elevated. Expression of GalC on endometrial glands is higher during the secretory phase than during the proliferative phase of the menstrual cycle. Because epithelial cells line the female reproductive tract and express HIV receptors and coreceptors, it is likely that they are one of the first cell types to become infected. The hormonal regulation of HIV receptor expression may affect a woman's susceptibility to HIV infection during her menstrual cycle. Moreover, selective coreceptor expression could account for the preferential transmission of R5‐HIV‐1 strains to women. In addition, these studies provide evidence that the uterus, and potentially the entire upper reproductive tract, are important sites for the initial events involved in HIV infection.
X‐chromosome‐linked immune‐deficient mice have B‐1b cells
Authors: Riggs J. , Howell K. , Matechin B. , Matlack R. , Pennello A. , Chiasson R. 
Published: December 2004

SummaryThe B lymphocyte subsets of X‐chromosome‐linked immune‐deficient (XID) mice were examined by flow cytometric analyses of spleen and peritoneal cells. As shown in prior studies, young adult XID mice had reduced representation of the CD5+ (B‐1a) subset in their peritoneal cavity. However, the CD11b+ (B‐1b) B‐cell subset was present and exhibited the IgMhi CD45lo CD23− phenotype characteristic of most B‐1 cells. Although present at a lower frequency than that found in their normal counterparts, B‐1b cells were evident in CBA/N and (XD2J)F1 male mice. With increasing age, B‐1b cell number increased and in the oldest XID mice were present as B‐cell chronic lymphocytic leukaemia. These results show that XID mice do have B‐1 cells, particularly the B‐1b subset.
TRAF6‐NF‐κB pathway is essential for interleukin‐1‐induced TLR2 expression and its functional response to TLR2 ligand in murine hepatocytes
Authors: Matsumura Takayuki , Degawa Takahiro , Takii Takemasa , Hayashi Hidetoshi , Okamoto Takashi , Inoue Jun‐ichiro , Onozaki Kikuo 
Published: December 2004

SummaryWe have previously reported that the expressions of TLR2 and TLR4 mRNA are differentially regulated in mouse liver and in the parenchymal cells. In the present study, we investigated the mechanism of the up‐regulatory effects of interleukin‐1α (IL‐1α), tumour necrosis factor‐α (TNF‐α), lipopolysaccharide (LPS), or bacterial lipoprotein (BLP) on TLR2 mRNA expression in primary cultured murine hepatocytes. Although TLR2 mRNA stability was not affected, these treatments enhanced NF‐κB activity and TLR2 gene transcription simultaneously. The up‐regulation of TLR2 transcription in response to these reagents was completely inhibited by blocking the NF‐κB activation pathway, demonstrating a pivotal role of NF‐κB activation in the regulation of hepatocyte TLR2 transcription. The expression of TLR2 protein by hepatocytes was also remarkably up‐regulated by IL‐1α and, to a lesser extent, by TNF‐α as well, but not by LPS or BLP. In addition, pretreatment of mice with IL‐1α markedly increased the BLP (a ligand for TLR2)‐induced serum level of serum amyloid A (SAA), an acute‐phase protein predominantly produced by hepatocytes, indicating that IL‐1α may also up‐regulate functional TLR2 in vivo. These results demonstrate that IL‐1α, through activating the TRAF6‐NF‐κB pathway, serves as the most potent inducer for TLR2 up‐regulation, and plays an important role in the regulation of hepatocyte functions by augmenting the hepatocyte response to bacteria or bacterial products.
Respiratory syncytial virus decreases the capacity of myeloid dendritic cells to induce interferon‐γ in naïve T cells
Authors: Bartz H. , Türkel Ö. , Hoffjan S. , Rothoeft T. , Gonschorek A. , Schauer U. 
Published: December 2004

SummaryRespiratory syncytial virus (RSV) is the most common cause of bronchiolitis in infants under 6 months of age. Since an RSV infection does not necessarily prevent a reinfection, we asked whether RSV might subvert an effective immune response by interfering with the function of dendritic cells (DCs). Immature DCs cultured from cord blood stem cells and infected with RSV reduced the rate of interferon‐γ (IFN‐γ) production in co‐cultured autologous naïve T cells stimulated with the superantigen TSST‐1. Maturation of DCs in response to poly(IC) but not to CD40 ligand did overcome the inhibitory effect of RSV. Further experiments demonstrated that induction of apoptosis, a selective increase in CD86 expression and lack of release of pro‐inflammatory cytokines were associated with inhibition of IFN‐γ generation. In addition, RSV replication seemed to be essential for modulation of IFN‐γ production because a virus preparation inactivated by UV irradiation had no effect. Hence, one reason for multiple reinfections by RSV might be the subversion of antiviral immune responses by interference of RSV with DC function.
Apoptotic cell death in conjunction with CD80 costimulation confers uveal melanoma cells with the ability to induce immune responses
Authors: Carlring Jennifer , Shaif‐Muthana Munitta , Sisley Karen , Rennie Ian G. , Murray Anna K. 
Published: December 2004

SummaryUveal melanoma is a rare malignancy with a poor prognosis despite current therapeutic intervention. The current investigation focuses on the immunogenicity of uveal melanoma cells genetically modified with recombinant adenovirus encoding CD80 (AdCD80) in contrast to their parental counterpart. We demonstrate that costimulation provided by uveal melanoma cells improved immune responses in vitro as determined by mixed lymphocyte tumour cell cultures and cytotoxic T‐cell assays using lymphocytes from healthy donors and uveal melanoma patients. Flow cytometry revealed T‐cell stimulation by activated CD4+ and CD8+ T cells. Additionally, autologous lymphocytes proliferated in response to CD80‐expressing primary uveal melanomas, indicating that this patient group is suitable for immunotherapy. Moreover, this study utilized AdCD80 modified and parental apoptotic tumour cells, loaded onto immature dendritic cells, as a source of tumour antigen. The ability of live or apoptotic tumour cells to stimulate lymphocyte proliferation and activation was determined. Apoptotic uveal melanoma cells expressing CD80 were efficient at inducing an immune response and served as a potent immunogen. The use of apoptotic uveal melanoma cells in combination with expression of costimulatory molecules could prove a novel adjuvant therapy for the treatment of this disease.
Heavy‐chain only antibodies derived from dromedary are secreted and displayed by mouse B cells
Authors: Nguyen Viet Khong , Zou Xiangang , Lauwereys Marc , Brys Lea , Brüggemann Marianne , Muyldermans Serge 
Published: December 2004

SummaryWhereas functional heavy (H)‐chain antibodies devoid of light (L)‐ chains account for about half of the circulating immunoglobulins in Camelidae, H‐chain only antibodies (HCAbs) are not produced in other healthy mammals including rodents and humans. To test the feasibility of expressing single chain antibodies in the mouse, which on account of their small size and antigen‐recognition properties would have a major impact on antibody engineering strategies, we constructed a rearranged dromedary H‐chain gene encoding the immunoglobulin G2a (IgG2a) isotype with specificity for hen‐egg lysozyme (HEL). This IgG2a H‐chain gene was introduced into mouse myeloma cells not expressing endogenous immunoglobulin H‐ or L‐chains. Unexpectedly the mouse cells processed and expressed the introduced H‐chain as naturally occurring dromedary antibody. For this the first constant (C) region exon was proficiently removed from the recombinant H‐chain transcript. This resulted in specific H‐chain antibodies of the correct molecular weight (2 × 50 000 MW) secreted as disulfide‐linked homodimers and displayed on the mouse cell surface as glycosyl‐phosphatidyl‐inositol‐linked B‐cell receptor. The results indicate that antibody expression and maturation without immunoglobulin L‐chain is feasible and paves the way for the generation of transgenic single chain antibody repertoires.
The influence of macrophage inflammatory protein‐1α on protective immunity mediated by antiviral cytotoxic T cells
Authors: Jones Emma , Price David A. , Dahm‐Vicker Michaela , Cerundolo Vincenzo , Klenerman Paul , Gallimore Awen 
Published: December 2004

SummaryMacrophage inflammatory protein 1α (MIP‐1α), a member of the CC‐chemokine subfamily, is known to induce chemotaxis of a variety of cell types in vivo. Although the role of MIP‐1α in inflammatory responses generated following primary infection of mice with many different pathogens has been characterized, the influence of this chemokine on the generation of antigen‐specific T‐cell responses in vivo is less well understood. This is important, as virus‐specific CD8+ T lymphocytes (CTL) play a crucial role in defence against viral infections, both acutely and in the long term. In this study, we compared the ability of wild‐type and MIP‐1α‐deficient (MIP‐1α−/−) mice to mount CTL responses specific for the immunodominant epitope derived from influenza nucleoprotein (NP366–374). Influenza‐specific CTL responses were compared with respect to frequency, cytotoxic activity and ability to clear subsequent infections with recombinant vaccinia viruses expressing the influenza NP. The results indicate that antiviral CTL generated in MIP‐1α−/− mice are slightly impaired in their ability to protect against a subsequent infection. However, impaired in vivo CTL‐mediated antiviral protection was found to be associated with reduced cytotoxicity rather than with a failure of the CTL to migrate to peripheral sites of infection.
Innate immune responses induced by CpG oligodeoxyribonucleotide stimulation of ovine blood mononuclear cells
Authors: Mena Angelo , Nichani Anil K. , Popowych Yurij , Godson Dale L. , Dent Donna , Townsend Hugh G. G. , Mutwiri George K. , Hecker Rolf , Babiuk Lorne A. , Griebel Philip 
Published: December 2004

SummaryExamples exist in the literature that demonstrate that treatment with immunostimulatory cytosine–phosphate–guanosine (CpG)‐DNA can protect mice against infection by intracellular pathogens. There are, however, few studies reporting that CpG‐DNA offers similar disease protection in other species. In this study, we assessed the potential of a class A and class B CpG oligodeoxynucleotide (ODN) to induce innate immune responses in sheep, an outbred species. Using peripheral blood mononuclear cells, we have for the first time demonstrated CpG‐ODN‐induced innate immune responses, including natural‐killer‐like activity [non‐major histocompatibility complex (MHC)‐restricted cytotoxicity], interferon‐α secretion and 2′‐5′A oligoadenylate synthetase activity, that could contribute to immune protection in sheep. The type and magnitude of these responses were dependent on ODN class and non‐MHC‐restricted killing was not associated with interferon‐γ production. The latter observation is in contrast with observations reported for mice and humans. These observations support the conclusion that differences in CpG‐ODN‐induced responses exist among species and that specific ODN sequences can significantly influence innate immune responses.
Senescence and age‐related reproduction of female Columbian ground squirrels
Authors: Broussard D. R. , Risch T. S. , Dobson F. S. , Murie J. O. 
Published: December 2004

Summary

Three hypotheses have been proposed to explain age‐structured patterns of reproductive investment and somatic investment: residual reproductive value, senescence and evolutionary restraint. We evaluated these hypotheses for female Columbian ground squirrels (Spermophilus columbianus) by examining age‐related patterns of somatic and reproductive investment. Females were designated as successful (those that weaned litters) and unsuccessful (those that did not wean litters).
Somatic investment varied among both successful and unsuccessful females of different ages, with yearlings having the highest investment. Considering all females, reproductive investment varied among age classes with yearlings and the oldest (6–9‐year‐olds) having the lowest investments. However, when only successful females were considered, reproductive investment was lowest in the yearlings and not significantly different among older females.
The highest proportion of successful females occurred in the middle adult age classes, while yearlings and the oldest females displayed the lowest proportion of successful females. During the breeding season, somatic investments of successful and unsuccessful females differed significantly only in the yearling age class, with unsuccessful females having the highest investment.
Evolutionary restraint or constraint explained patterns of reproduction in the yearling age class, where both reproductive investment and proportion of reproductive females were low. There was evidence for senescence of reproduction by some of the oldest females.
Dispersal pattern of domestic cats (Felis catus) in a promiscuous urban population: do females disperse or die?
Authors: Devillard Sébastien , Say Ludovic , Pontier Dominique 
Published: December 2004

SummaryThe domestic feral cat (Felis catusL.) is a good model for studying intraspecific variability of dispersal patterns in mammals because cats live under a large diversity of socio‐ecological conditions. We analysed both the natal and breeding dispersal patterns of domestic cats in a promiscuous urban population and tested whether or not it differed from the male‐biased natal dispersal pattern observed for polygynous rural populations.During an 8‐year study we recorded the exact date ofin situdeath for 148 marked cats and the exact date of disappearance from the population for 99 other cats. Because undiscovered deaths might over‐estimate dispersal probabilities when considering only disappearance probabilities, we made an novel application of multistrata capture–recapture methods in order to disentangle dispersal from true mortality.We showed that mature females dispersed, both before and after their first reproduction, at 1 and 2 years old. Contrary to females, no dispersal seemed to occur in males. Before sexual maturity, females that disappeared at 1 and 2 years old were in worse body condition than females that stayed in the population area after 2 years old. However, they did not reproduce less successfully before their disappearance than females that died later in the population area.The female‐biased and low natal dispersal pattern in this population was atypical compared to other promiscuous/polygynous mammals and differed from that observed in rural polygynous populations of domestic cat. Neither local mate competition nor inbreeding avoidance appeared to be sufficient pressures to counterbalance ecological constraints on dispersal in an urban environment. However, local resource competition for den sites between potential matriarchies could lead to the breeding dispersal of less competitive females.
Spatial refugia and the coexistence of a diurnal raptor with its intraguild owl predator
Authors: Sergio Fabrizio , Marchesi Luigi , Pedrini Paolo 
Published: December 2004

SummaryIntraguild predation (IGP) has been studied extensively in predatory fish, amphibians and mammals, but less so in top avian predators. We studied the impact of IGP by large eagle owlsBubo buboLinnaeus (body mass ∼1·5–4 kg) on diurnal black kitesMilvus migransBoddaert (∼0·5–1 kg) in eight populations located in the Italian Alps. Eagle owls preyed on both adult and nestling kites, especially when kites nested within 2 km of an owl nest. Food overlap was low as kites preyed mainly on fish and owls on mammals. Eagle owls were absent from two study areas, bred very close to another area and were present at medium–high densities in the other five. Within‐population effects varied and were most severe in areas with high owl densities. Overall, kites responded to predation risk through predator spatial avoidance, being concentrated in interstitial predation‐refugia bordering the core home range of owl pairs.Kite productivity declined steeply with increasing predation risk; no nestling fledged within 1 km of an owl nest. Brood predation was higher in an area with medium owl density than in an area lacking eagle owls.The abandonment of kite territories increased near owl nests, but close coexistence was maintained by new kite territories being established occasionally in areas of high predation risk and high food abundance, which probably functioned as ecological traps. Compared to a random nest dispersion, colonial nesting was avoided within 1 km of an owl pair and peaked in conditions of medium predation risk.At the population level, kite density and productivity were related to a complex interaction of IGP risk and food abundance, and were probably shaped by a mixture of top‐down and bottom‐up effects. These results may apply to many other vertebrate mesopredators, whose individual decisions and population responses are probably the result of a trade‐off between predator avoidance and food acquisition.At the community level, the density of different diurnal avian predators responded differently to IGP risk, some of them even increasing with this risk. The diversity of the assemblage peaked at medium–high eagle owl density. Future studies of top vertebrate predators need to take more account of IGP effects. Their conservation management needs to be highly case‐specific and framed within a broader ecosystem perspective.
Bill dimorphism and foraging niche partitioning in the green woodhoopoe
Authors: Radford Andrew N. , Du Plessis Morné A. 
Published: December 2004

Summary

Cooperatively breeding green woodhoopoes, Phoeniculus purpureus, forage mainly as close‐knit groups, creating opportunities for intrasexual and intersexual foraging competition.
Adult males foraged on wider branches than adult females, probably as a consequence of their larger body size (5–8%). Moreover, adult males spent more time scaling bark and probing the ends of broken branches, while adult females preferred pecking. There was no intersexual difference in the use of hole probing or surface gleaning.
Intersexual differences in foraging technique probably resulted from morphological differences: adult male bills were 36% longer than those of females, with no overlap between the sexes. In support of the specialization hypothesis: (a) birds were more likely to forage in close proximity to a member of the opposite sex; (b) there was more intrasexual than intersexual aggression during foraging; (c) lone females did not change their foraging behaviour from when in close proximity to a male; (d) the niche breadth of both sexes was similar; and (e) juveniles foraged in ways predicted from their bill lengths. On fledging, bills of juvenile males and females were the same length as those of adult females, and all juveniles fed like adult females. After 4 months, the bills of juvenile males exceeded those of adult females, and they began to forage like adult males.
Adult males brought different invertebrate taxa and heavier prey to the nest than females. These differences were a consequence of the different foraging techniques used, because both sexes collected the same types of prey when using the same technique.
When all group members foraged together, dominant adults spent more time hole probing than subordinates of the same sex. This intrasexual difference probably resulted from interference competition, as dominants and subordinates did not differ in bill length, and dominants excluded subordinates from prime feeding areas.
To compensate, subordinate adults did not increase their foraging time or collect larger prey items than dominants, but more often left the group to forage alone. When alone, subordinates spent more time hole probing and experienced higher foraging success than when in a group.
The effects of an exotic fish invasion on the prey communities of two lakes
Authors: Beisner Beatrix E. , Ives Anthony R. , Carpenter Stephen R. 
Published: December 2004

Summary

We examined changes in prey (zooplankton) communities resulting from the invasion of an exotic predator, the rainbow smelt (Osmerus mordax Mitchill), using long‐term data sets from two lakes in Wisconsin, USA.
Food webs in the two lakes differed originally both in the dominant native planktivorous fish species and in relative biomasses of major zooplankton groups.
Zooplankton communities in each lake changed dramatically, coinciding with the exotic predator invasion. The communities in the two lakes became more similar to each other, with cyclopoid copepods becoming dominant.
Time‐series analyses demonstrated that the long‐term responses of the two lake prey communities were driven primarily by direct predation effects of planktivorous fish. Indirect effects acting through competitive interactions among zooplankton were present but were comparatively small in the long term.
Results suggest that zooplankton populations were subject to both predator and resource limitation but that the composition (relative species abundance) of the zooplankton community was dictated in the long term by predation.