bluuebunny/crossref_metadata_2025 huggingface dataset:
Early and late failure of noninvasive ventilation in chronic obstructive pulmonary disease with acute exacerbation
Authors: Carratù P. , Bonfitto P. , Dragonieri S. , Schettini F. , Clemente R. , Di Gioia G. , Loponte L. , Foschino Barbaro M. P. , Resta O.
Published: June 2005

Background  Despite recent encouraging results, the use of noninvasive ventilation (NIV) in the management of acute exacerbations in chronic obstructive pulmonary disease (COPD), complicated by acute respiratory failure (ARF), is not always successful. Failure of NIV may require an immediate intubation after a few hours (usually 1–3) of ventilation (‘early failure’) or may result in clinical deterioration (one or more days later) after an initial improvement of blood gas tension and general conditions (‘late failure’).

Materials and methods  We enrolled 122 patients affected by COPD complicated by ARF, and treated with NIV. The schedule of NIV provided sessions of 2–6 h twice daily.

Results  Ninety‐nine (81%) patients showed a progressive improvement of the clinical parameters and were discharged. Among the remaining 23 patients, 13 had an early failure and 10 had a late failure. In the ‘success’ group and ‘late failure’ groups we found after an increase of pH 2 h of NIV (from 7·31 ± 0·05 to 7·38 ± 0·04 P < 0·001 and from 7·29 ± 0·03 to 7·36 ± 0·02 P < 0·001, respectively) and a decrease of PaCO2 (from 80·93 ± 9·79 to 66·48 ± 5·95 P < 0·001 and from 85·96 ± 10·77 to 76·41 ± 11·02 P < 0·001, respectively). After 2 h of NIV in the ‘late failure’ group there were no significant changes in terms of pH (from 7·20 ± 0·10 to 7·28 ± 0·06) nor PaCO2 (from 92·86 ± 35·49 to 93·68 ± 23·68). The ‘early failure’ group had different characteristics and, owing to more severe conditions, the value of pH, of Glasgow Coma Score, and Apache II Score were the best predictors of the failure; while, among the complications on admission, metabolic alterations were the only independently significant predictor.

Conclusions  Our study confirms that NIV may be useful to avoid intubation in approximately 80% of patients with COPD complicated by moderate‐severe hypercapnic respiratory failure.
Carcinoma ex pleomorphic adenoma (CXPA): immunoprofile of the cells involved in carcinomatous progression
Authors: Altemani A , Martins M T , Freitas L , Soares F , Araújo N S , Araújo V C
Published: June 2005

Aims : To characterize the cellular component in pleomorphic adenoma (PA) that undergoes malignant transformation in carcinoma ex pleomorphic adenoma (CXPA).

Methods and results : A panel of antibodies against cytoskeletal proteins was applied in 16 cases of CXPA: intracapsular carcinoma (five cases), minimally invasive (four cases) and frankly invasive (seven cases). The CXPAs were classified into two main groups according to their predominant cellular component as detected by the panel of antibodies: (i) carcinomas with only epithelial differentiation (75% of the cases), and (ii) carcinomas with a myoepithelial component (25%). CXPA with only epithelial differentiation showed two types of malignant areas in the part of the tumour that was confined by the PA capsule: (i) intraductal carcinoma areas characterized by ductal structures containing both benign myoepithelial cells positive for α‐smooth muscle actin (α‐SMA), vimentin and cytokeratin (CK)14 and proliferating atypical luminal cells reactive for CK7, CK8 and CK19, and (ii) carcinoma areas composed only of epithelial cells reactive for CK7, CK8 and CK19. In the latter, the cells presented morphological and immunohistochemical characteristics similar to those found in areas of invasive carcinoma outside the PA capsule. CXPAs with a myoepithelial component were composed mainly or exclusively of cells that expressed vimentin and α‐SMA. In this group, ductal structures reminiscent of PA filled by malignant cells were not identified.

Conclusion : Most CXPAs consist only of epithelial cells that have an immunoprofile comparable to ductal luminal cells of PA. These malignant luminal cells arise in the duct‐like structures as intraductal carcinoma and probably only at this early stage of development should the lesion be considered as a non‐invasive carcinoma.
Up‐regulation of macrophage migration inhibitory factor in infants with acute neonatal necrotizing enterocolitis
Authors: Ren Y , Lin C L , Li Z , Chen X Y , Huang X , Lui V , Nicholls J , Lan H Y , Tam P K H
Published: June 2005

Aims:  To investigate the role of macrophage migration inhibitory factor (MIF) and its downstream cytokine cascade in necrotizing enterocolitis (NEC).

Methods and results:  The expression of MIF mRNA and protein in NEC guts was assayed by in situ hybridization and immunohistochemistry, respectively. Concentrations of MIF, interleukin (IL)‐6 and IL‐8 in the serum and in the supernatant of macrophage cultures were examined by ELISA. Increased expression of MIF mRNA and protein was observed in the NEC guts, mainly in the infiltrating macrophages in the mucosa and submucosal layers. Up‐regulation of MIF was associated with the accumulation of macrophages and T cells. In addition, serum levels of MIF, IL‐6 and IL‐8 in NEC patients during the acute stage of the disease were significantly increased. The expression of MIF decreased both locally and systemically after the disease was resolved. MIF was also found to increase the secretion of IL‐6 and IL‐8 by macrophages isolated from healthy individuals in vitro in NEC.

Conclusions:  MIF acts by stimulating macrophage production of IL‐6 and IL‐8. This further aggravates the inflammatory process by increasing the infiltration of neutrophils and activating inflammatory cells. The results of this study suggest that MIF plays an important role in the pathogenesis of NEC and may serve as a target for therapeutic intervention in NEC.
Expression of hypoxia‐inducible factors is correlated with the presence of a fibrotic focus and angiogenesis in pancreatic ductal adenocarcinomas
Authors: Couvelard A , O'Toole D , Leek R , Turley H , Sauvanet A , Degott C , Ruszniewski P , Belghiti J , Harris A L , Gatter K , Pezzella F
Published: June 2005

Aims:  To study the expression of hypoxia‐regulated markers in pancreatic ductal adenocarcinomas (PA) in relationship to the presence of a fibrotic focus, angiogenesis quantification and clinical outcome.

Methods and results:  The expression of hypoxia‐inducible factor (HIF)‐1α, HIF‐2α, carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) was immunohistochemically detected in 50 PA and correlated with tumour characteristics, microvascular density (MVD) and survival. HIF‐1α was expressed within tumour cells in 68%, HIF‐2α in 46%, CA9 in 78% and VEGF in 52% of the cases. Stromal expression was also noted for HIF‐2α and CA9 in, respectively, 42% and 48% of the cases. Tumour CA9 expression was associated with that of VEGF (P = 0.004) and that of stromal HIF‐2α (P = 0.013), with the presence of a fibrotic focus (P = 0.046) and with an increased MVD (P = 0.034). Tumour VEGF expression correlated with the presence of a fibrotic focus (P = 0.039) and a greater MVD (P = 0.047). Both the presence of a fibrotic focus (P = 0.0002) and high tumour CA9 expression (P = 0.029) were associated with reduced overall survival.

Conclusion:  The strong association of the presence of a fibrotic focus with CA9 expression and lower survival demonstrates that hypoxia‐driven angiogenesis plays an important role in the progression of PA.
The flavonoid luteolin prevents lipopolysaccharide‐induced NF‐κB signalling and gene expression by blocking IκB kinase activity in intestinal epithelial cells and bone‐marrow derived dendritic cells
Authors: Kim Joo Sung , Jobin Christian
Published: June 2005

The nuclear factor (NF)‐κB transcriptional system is a major effector pathway involved in inflammation and innate immune responses. The flavonoid luteolin is found in various herbal extracts and has shown anti‐inflammatory properties. However, the mechanism of action and impact of luteolin on innate immunity is still unknown. We report that luteolin significantly blocks lipopolysaccharide (LPS)‐induced IκB phosphorylation/degradation, NF‐κB transcriptional activity and intercellular adhesion molecule‐1 (ICAM‐1) gene expression in rat IEC‐18 cells. Using chromatin immunoprecipitation, we demonstrate that LPS‐induced RelA recruitment to the ICAM‐1 gene promoter is significantly reduced in luteolin‐treated cells. Moreover, in vitro kinase assays show that luteolin directly inhibits LPS‐induced IκB kinase (IKK) activity in IEC‐18 cells. Using bone‐marrow derived dendritic cells (BMDCs) isolated from interleukin (IL)‐10–/– mice or from recently engineered transgenic mice expressing the enhanced green fluorescent protein (EGFP) under the transcriptional control of NF‐κB cis‐elements (cis‐NF‐κBEGFP), we found that luteolin blocks LPS‐induced IκB phosphorylation and IKK activity, and decreases EGFP, IL‐12 and tumour necrosis factor‐α gene expression. Moreover, intraperitoneal administration of luteolin significantly inhibited LPS‐induced EGFP expression in both peripheral blood mononuclear cells and splenocytes isolated from cis‐NF‐κBEGFP mice. These results indicate that luteolin blocks LPS‐induced NF‐κB signalling and proinflammatory gene expression in intestinal epithelial cells and dendritic cells. Modulation of innate immunity by natural plant products may represent an attractive strategy to prevent intestinal inflammation associated with dysregulated innate immune responses.
Ethnic variation of Fcγ receptor polymorphism in Sami and Norwegian populations
Authors: Torkildsen Øivind , Utsi Egil , Mellgren Svein Ivar , Harbo Hanne F. , Vedeler Christian A. , Myhr Kjell‐Morten
Published: June 2005

Receptors for the Fc domain of IgG (FcγR) play a critical role in linking cellular and humoral immunity. The various FcγR genotypes may contribute to differences in infectious and immune‐related diseases in various ethnic populations. The Samis are the aboriginal inhabitants of Norway and Fennoscandinavia and differ ethnically from the Norwegians. The distribution of various immune‐related diseases has been reported to differ between Sami and Norwegians. This is the first study to evaluate the distribution of FcγR polymorphisms in a Sami population. Two hundred Samis were genotyped for polymorphisms in the FcγRIIA, FcγRIIIA and FcγRIIIB genes. The genotype and allele frequencies were compared with those of 272 healthy Norwegians. The Sami and Norwegian FcγRIIA, FcγRIIIA and FcγRIIIB genotypes differed significantly. The Samis had higher frequencies of the FcγRIIa‐H/H131, FcγRIIIa‐F/F158 and FcγRIIIb‐NA1/NA1 genotypes. The FcγR genotypes were non‐randomly distributed in both populations. These findings may be important for the prevalence of autoimmune and infectious diseases in the two populations.
Lipoteichoic acid induces nuclear factor‐κB activation and nitric oxide synthase expression via phosphatidylinositol 3‐kinase, Akt, and p38 MAPK in RAW 264.7 macrophages
Authors: Kao Shang‐Jyh , Lei Hui‐Chieh , Kuo Chen‐Tzu , Chang Ming‐Shyan , Chen Bing‐Chang , Chang Yau‐Chong , Chiu Wen‐Ta , Lin Chien‐Huang
Published: June 2005

We previously demonstrated that lipoteichoic acid (LTA) might activate phosphatidylcholine‐phospholipase C (PC‐PLC) and phosphatidylinositol‐phospholipase C (PI‐PLC) to induce protein kinase C activation, which in turn initiates nuclear factor‐κB (NF‐κB) activation and finally induces inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release in RAW 264.7 macrophages. In this study, we further investigated the roles of tyrosine kinase, phosphatidylinositiol 3‐kinase (PI3K)/Akt, and p38 mitogen‐activated protein kinase (MAPK) in LTA‐induced iNOS expression and NO release in RAW 264.7 macrophages. Tyrosine kinase inhibitors (genistein and tyrphostin AG126), PI3K inhibitors (wortmannin and LY 294002), and a p38 MAPK inhibitor (SB 203580) attenuated LTA‐induced iNOS expression and NO release in concentration‐dependent manners. Treatment of RAW 264.7 macrophages with LTA caused time‐dependent activations of Akt and p38 MAPK. The LTA‐induced Akt activation was inhibited by wortmannin, LY 294002, genistein, and tyrphostin AG126. The LTA‐induced p38 MAPK activation was inhibited by genistein, tyrphostin AG126, wortmannin, LY 294002, and SB 203580. The LTA‐induced formation of an NF‐κB‐specific DNA–protein complex in the nucleus was inhibited by wortmannin, LY 294002, genistein, tyrphostin AG126, and SB 203580. Treatment of macrophages with LTA caused an increase in κB‐luciferase activity, and this effect was inhibited by tyrphostin AG126, wortmannin, LY 294002, the Akt dominant negative mutant (AktDN), and SB 203580. Based on those findings, we suggest that LTA might activate the PI3K/Akt pathway through tyrosine kinase to induce p38 MAPK activation, which in turn initiates NF‐κB activation, and ultimately induces iNOS expression and NO release in RAW 264.7 macrophages.
Multivalent recombinant proteins for probing functions of leucocyte surface proteins such as the CD200 receptor
Authors: Voulgaraki Despina , Mitnacht‐Kraus Rita , Letarte Michelle , Foster‐Cuevas Mildred , Brown Marion H. , Barclay A. Neil
Published: June 2005

CD200 (OX2) is a membrane glycoprotein that interacts with a structurally related receptor (CD200R) involved in the regulation of macrophage function. The interaction is of low affinity (KD ∼ 1 μm) but can be detected using CD200 displayed in a multivalent form on beads or with dimeric fusion proteins consisting of the extracellular region of CD200 and immunoglobulin Fc regions. We prepared putative pentamers and trimers of mouse CD200 with sequences from cartilage oligomeric matrix protein (COMP) and surfactant protein D (SP‐D), respectively. The COMP protein gave high‐avidity binding and was a valuable tool for showing the interaction whilst the SP‐D protein gave weak binding. In vivo experiments showed that an agonistic CD200R monoclonal antibody caused some amelioration in a model of experimental autoimmune encephalomyelitis but the COMP protein was cleared rapidly and had minimal effect. Pentameric constructs also allowed detection of the rat CD48/CD2 interaction, which is of much lower affinity (KD ∼ 70 μm). These reagents may have an advantage over Fc‐bearing hybrid molecules for probing cell surface proteins without side‐effects due to the Fc regions. The CD200‐COMP gave strong signals in protein microarrays, suggesting that such reagents may be valuable in high throughput detection of weak interactions.
Inhibition of immunoglobulin E synthesis through FcγRII (CD32) by a mechanism independent of B‐cell receptor co‐cross‐linking
Authors: Horejs‐Hoeck Jutta , Hren Andrea , Mudde Geert C. , Woisetschläger Maximilian
Published: June 2005

The inhibitory effect on antibody production by immune complexes has been shown to depend on co‐ligation of the B‐cell antigen receptor (BCR) with the low‐affinity receptor for immunoglobulin G (IgG) (FcγRIIb, CD32). Here we report that immunoglobulin E (IgE) synthesis, induced in a BCR‐independent manner by interleukin‐4 (IL‐4) and anti‐CD40 antibody, was inhibited by CD32 ligation. The observed effect was specific for CD32 as, first, antibodies directed against other B‐cell surface structures had no inhibitory effect, and, second, treatment with anti‐CD32 of cells that had been in culture for 2 days was ineffective owing to the down‐regulation of CD32 expression. IgE inhibition was also observed in cells stimulated by IL‐4/CD40 F(ab′)2 or IL‐4 plus soluble CD40 ligand, demonstrating that co‐cross‐linking of CD32 and CD40 was not necessary to induce inhibition. Mechanistic studies into the IgE class switch process demonstrated that IL‐4/anti‐CD40‐induced IgE germline gene transcription and B‐cell proliferation were not affected by CD32 ligation. The data demonstrate that the negative regulatory role of the CD32 molecule is not restricted to BCR‐induced B‐cell activation, but is also functional on other B‐cell activation pathways mediated by CD40 and IL‐4.
Maintenance of long‐term tumour‐specific T‐cell memory by residual dormant tumour cells
Authors: Mahnke Yolanda D. , Schwendemann Jochen , Beckhove Philipp , Schirrmacher Volker
Published: June 2005

LacZ (Gal)‐reactive immune cells were transferred into athymic nu/nu mice inoculated with Gal‐expressing syngeneic tumour cells (ESbL‐Gal) in order to study tumour‐protective T‐cell memory. This transfer prevented tumour outgrowth in recipients and resulted in the persistence of a high frequency of Gal‐specific CD8+ T cells in the bone marrow and spleen. In contrast, such Ag‐specific memory CD8+ T cells were not detectable by peptide–major histocompatibility complex (MHC) multimer staining in animals that had not previously received an antigenic challenge. Even though CD44hi memory T cells from the bone marrow showed a significantly higher turnover rate, as judged by bromodeoxyuridine (BrdU) incorporation, than respective cells from spleen or lymph nodes, as well as in comparison to CD44lo naïve T cells, these findings suggest that tumour‐associated antigen (TAA) from residual dormant tumour cells are implicated in maintaining high frequencies of long‐term surviving Gal‐specific memory CD8+ T cells. Memory T cells could be recruited to the peritoneal cavity by tumour vaccination of immunoprotected nu/nu mice and exhibited ex vivo antitumour reactivity. Long‐term immune memory and tumour protection could be maintained over four successive transfers between tumour‐inoculated recipients, which involved periodic antigenic restimulation in vivo prior to reisolating the cells for adoptive transfer. Using a cell line (ESbL‐Gal‐BM) that was established from dormant tumour cells isolated from the bone marrow of immunoprotected animals, it could be demonstrated that the tumour cells had up‐regulated the expression of MHC class I molecules and down‐regulated the expression of several adhesion molecules during the in vivo passage. Our results suggest that the bone marrow microenvironment has special features that are of importance for the maintenance of tumour dormancy and immunological T‐cell memory, and that a low level of persisting antigen favours the maintenance of Ag‐specific memory T cells over irrelevant memory T cells.
Circulating anti‐retinal antibodies as immune markers in age‐related macular degeneration
Authors: Patel Nishal , Ohbayashi Masahara , Nugent Alex K. , Ramchand Kanchan , Toda Masako , Chau Kai‐Yin , Bunce Catey , Webster Andrew , Bird Alan C. , Ono Santa Jeremy , Chong Victor
Published: June 2005

Age‐related macular maculopathy (ARM) and age‐related macular degeneration (AMD) are the leading causes of blindness in the Western world. Despite the magnitude of this clinical problem, very little is known about the pathogenesis of the disease. In this study, we analysed the sera (using indirect immunohistochemistry and Western blot analysis) from a very large cohort of such patients and normal age‐matched controls to detect circulating anti‐retinal antibodies. Patients with bilateral drusen (n = 64) and with chorioretinal neovascularization (CNV) (n = 51) were recruited in addition to age‐matched control subjects (n = 39). The sera were analysed for anti‐retinal immunoglobulins on retinal sections. The data were then correlated with the clinical features graded according to the International Classification and Grading System of ARM and AMD. The sera of patients with drusen (93·75%) and CNV (82·27%) were found to have a significantly (P = 0·02) higher titre of autoantibodies to the retina in comparison with controls (8·69%), indicating significant evidence of involvement of the immune process in early stages of AMD. Subsequent statistical analysis of the drusen group showed significant progressive staining (P = 0·0009) in the nuclei layers from early to late stages of ARM. Western blotting confirmed the presence of anti‐retinal immunoglobulins to retinal antigens. As anti‐retinal immunoglobulins are present in patients with bilateral drusen and exudative AMD, these antibodies could play a significant role in the pathogenesis of AMD. Whilst we do not have evidence that these antibodies precede disease onset, the possibility that their presence might contribute to disease progression needs to be investigated. Finally, the eventual identification of the target antigens detected by these antibodies may permit the future development of new diagnostic methods for ARM and AMD.
Expression of regulator of G protein signalling proteins in natural killer cells, and their modulation by Ly49A and Ly49D
Authors: Kveberg Lise , Ryan James C. , Rolstad Bent , Inngjerdingen Marit
Published: June 2005

The small GTPase accelerators regulator of G protein signalling (RGS) proteins are important regulators of proximal signalling from G protein coupled receptors. Although natural killer (NK) cells express a number of G‐protein coupled receptors, expression of RGS proteins has not been investigated. We analysed the expression of RGS proteins in rat NK cells, and detected mRNA for RGS1, RGS2, RGS5, RGS8, RGS16, and RGS18. Interestingly, when we included a panel of different leucocyte subsets, we found that RGS8 was selectively expressed by NK cells. NK cells are under control of both activating and inhibitory receptors and, utilizing a xenogeneic system where the mouse activating Ly49D or inhibitory Ly49A receptors were transfected into the rat RNK‐16 cell line, the potential regulation of RGS proteins by single NK cell receptors was studied. We found that ligation of Ly49D led to a rapid and transient increase in message for RGS2, while Ly49A ligation up‐regulated RGS2, RGS16, and RGS18 mRNA. Both receptors also induced a prolonged increase in RGS2 endogenous protein levels. These findings suggest that RGS proteins may be influenced by or involved in NK cell receptor events, suggesting a crosstalk between G‐protein coupled receptors and NK cell receptors.
Integrin CD11a cytoplasmic tail interacts with the CD45 membrane‐proximal protein tyrosine phosphatase domain 1
Authors: Geng Xin , Tang Ren‐Hong , Law S. K. Alex , Tan Suet‐Mien
Published: June 2005

Leucocyte adhesion receptor integrin CD11aCD18 and the transmembrane receptor‐like protein tyrosine phosphatase (RPTP) CD45 mediate immune synapse formation and signalling during antigen presentation. Previous cocapping studies on human naïve T cells demonstrate an interaction between CD11aCD18 and CD45. CD45 cross‐linking also has an effect on the ligand‐binding activity of CD11aCD18. However, the mode of interaction between CD11aCD18 and CD45 remains unclear. Herein, yeast two‐hybrid analysis identified a partial CD45 cytoplasmic tail interacting with that of CD11a. The CD45 cytoplasmic tail comprises a membrane proximal (Mp) region, protein tyrosine phosphatase domain 1 (D1), spacer, D2, and carboxyl terminus. CD45 Mp‐D1 was found to be the main interacting region for the CD11a cytoplasmic tail. In contrast, the full‐length CD45 cytoplasmic tail interacted weakly with that of CD11a. It has been reported that CD45 Mp‐D1 but not the full‐length cytoplasmic tail forms a homodimer whose enzymatic activity is inhibited. Our in vitro binding and enzymatic assays showed that the homodimeric CD45 cytoplasmic tail interacts with that of CD11a. The biological function of CD45 dimerization and its association with CD11a remains to be investigated.
Supplementation of CXCL12 (CXCL12) induces homing of CD11c+ dendritic cells to the spleen and enhances control of Plasmodium berghei malaria in BALB/c mice
Authors: Garnica Margoth Ramos , De Moraes Luciana Vieira , Rizzo Luiz Vicente , De Andrade Heitor Franco
Published: June 2005

In malaria, parasitaemia is controlled in the spleen, a multicomponent organ that undergoes changes in its cellular constituents to control the parasite. During this process, dendritic cells (DCs) orchestrate the positioning of effector cells in a timely manner for optimal parasite clearance. We have recently demonstrated that CXCL12 [stromal cell‐derived factor‐1 (CXCL12)] supplementation partially restores the ability to control parasitaemia in Plasmodium berghei‐infected mice. In the present study, we investigated the nature of the DCs involved by flow cytometry and immunohistochemistry of CD11c+ cells. Flow cytometry of bone marrow cells showed that infection with P. berghei did not alter the proportion of CD11c+ cells present in this haematopoietic compartment, while CXCL12 supplementation of naïve uninfected mice induced only minor increases in the population of CD11c+ cells. In the spleen, P. berghei infection alone resulted in an increase in CD11c+ cells as compared with naïve animals. Exogenously administered CXCL12 in the absence of infection resulted in a significant expansion of the splenic CD11c+ population, and this effect was even more pronounced in infected and supplemented mice. Immunohistochemistry revealed that CD11c+ cells infiltrated the perivascular areas and marginal zone of the spleen in infected animals treated with CXCL12, suggesting that this chemokine induces homing of CD11c+ dendritic cells to the splenic compartment. Our results show that small amounts of CXCL12 supplementation are effective in recruiting DCs to the spleens of both uninfected and infected mice, suggesting the participation of CXCL12 and CD11c+ cells in the establishment of an adequate environment in the spleen for malaria control.
A model of ruddy duck Oxyura jamaicensis eradication for the UK
Authors: SMITH G. C. , HENDERSON I. S. , ROBERTSON P. A.
Published: June 2005

Non‐native species are the second most important threat to global biodiversity after habitat loss. The North American ruddy duck Oxyura jamaicensis established a feral population in the UK more than 40 years ago, and it is now threatening the endangered white‐headed duck Oxyura leucocephala through hybridization. We utilized a simple generic model, which includes uncertainty in parameter estimates and can be used for any invasive species, to assess the time frame for successful control.

A simple spreadsheet‐based model was produced to provide the UK government with an assessment of whether sufficient ruddy ducks could be culled to allow the UK population to be reduced to fewer than 175 individuals (> 97% population reduction) within 10 years.

Data on changes in numbers of ruddy duck at the main UK wintering sites were collected during a regional control trial, and a stochastic Monte Carlo simulation model was constructed to project the UK population under a variety of control strategies. Three variables were included in the model: cull rate per person (i.e. by how much each control officer could reduce the national population per year), number of control officers, and changes in the ruddy duck population growth rate as the population was reduced.

Parameter estimation was kept to a minimum by using historical annual population growth rates as a basis for future growth rates. The historical data show a reduction in both the mean growth rate and in its variability when the population is in excess of 2000 birds. Density‐dependent and density‐independent models were produced. These all gave similar times to reach the target population, with some difference in the variance estimates between models.

Simulations were run with a maximum annual population reduction of between 0·50 and 0·80, and between 12 and 20 control officers. A total of 8000 simulations was performed for each of the 63 different scenarios for each of the models.

The mean time to reduce the UK ruddy duck population by 97% was predicted to be between 3 and 5 years, with 14 or 15 control officers reducing the population by between 65% and 70% per year. There was an 80% certainty that the population could be reduced to this level by 16 control officers within 4–6 years if annual reductions of more than 60% were achieved.

Synthesis and applications. The novel spreadsheet model presented here can easily be applied to a range of eradication schemes where limited data are available on population size and culling efficacy. This would allow funding bodies to have a greater degree of certainty about the cost and outcome of a trial eradication programme.
Nitrogen saturation in UK moorlands: the critical role of bryophytes and lichens in determining retention of atmospheric N deposition
Authors: CURTIS C. J. , EMMETT B. A. , GRANT H. , KERNAN M. , REYNOLDS B. , SHILLAND E.
Published: June 2005

Anthropogenic nitrogen (N) deposition may have several impacts on upland moorland ecosystems, including changes in vegetation composition, eutrophication and surface water acidification through nitrate leaching, but few studies linking N deposition to key biogeochemical processes have been published.

A stable isotope tracer (15N) was used to determine the fate of inorganic N inputs to four moorland catchments across gradients of N deposition and leaching, through 2‐weekly additions to experimental plots on major soil types over 1 year.

An apparent decline in total 15N recovery from soils and vegetation as the proportion of leached N deposition increased was not significant at the P = 0·05 level, but a significant relationship was found for recovery in mosses and lichens.

Vegetation retained 31–68% of 15N inputs, and 15N recovery increased significantly (P = 0·01) with biomass for all compartments except woody shrubs. Mosses and lichens showed far greater 15N recovery per unit biomass than grasses or ericaceous shrubs. There was no significant variation in the proportion of 15N recovered in higher plants across the N deposition gradient (24–29%). In contrast, the proportion recovered in mosses and lichens declined from 44% to 2% as deposition increased, mirroring a decline in their biomass and showing a highly significant inverse relationship (P = 0·01) with nitrate leaching.

The proportion of 15N recovered in litter plus surface soils (33–39%) was remarkably constant across the deposition gradient for a variety of soil types. However, significantly declining recovery per unit biomass in litter (P < 0·05) suggested progressive N saturation of this sink and increasing importance of retention in underlying surface soils as deposition increased.

Synthesis and applications. Past studies have demonstrated a decline in mosses and lichens in response to increasing N deposition, but we show here for the first time that reduced N retention might result together with increased nitrate leaching into surface waters. The conservation of bryophyte and lichen flora on moorlands is therefore critical to prevent excessive nitrate leaching and associated surface water acidification and eutrophication. Ensuring management practices such as grazing or burning are at an intensity that does not further degrade the bryophyte and lichen communities may help minimize the impact of N deposition on freshwaters, but the only effective means to reduce the risk of N leaching is a reduction in N emissions.
Differences in invasibility of two contrasting habitats and invasiveness of two mugwort Artemisia vulgaris populations
Authors: BARNEY JACOB N. , DI TOMMASO ANTONIO , WESTON LESLIE A.
Published: June 2005

Establishment success of non‐native invasive species is often attributable either to habitat invasibility or inherent species traits. In this study we explored the interplay between these two factors in the establishment, expansion and plasticity in growth of the clonally reproducing invasive weed mugwort Artemisia vulgaris in two contrasting habitats, as well as the potential management practice of monthly mowing.

We investigated resource allocation patterns and spatial distribution of ramets originating from two naturalized populations over a 3‐year period. Ramets from these morphologically distinct populations were transplanted into each of two contrasting habitats to determine the invasive potential of these populations and the relative resistance of each habitat to invasion.

Total ramet production, average ramet height and spatial distribution patterns differed significantly between the two populations, but the degree of variation in the response was habitat dependent. There were no interpopulation differences in total biomass production. Plastic responses in resource allocation patterns, spatial distribution of ramets and relative growth rates were observed, demonstrating differences in invasive potential between the two mugwort populations.

The two habitats differed in invasibility. This could have been the result of differences in community structure, competition for available resources, disturbance and/or invader traits. In addition, monthly defoliation (mowing) reduced mugwort ramet production by as much as 90% and as little as 10%.

Synthesis and applications. This study demonstrates that variation exists in habitat invasibility, and that intraspecific variation in growth patterns occurs in mugwort. The interaction between habitat traits and species characteristics was found to be important when determining invasion success. We also demonstrated that monthly mowing following the introduction of mugwort can substantially decrease the rate of spread of this clonal species, which may provide an effective management opportunity both for this species and for other clonal invaders.
Dispersal patterns in a harvested willow ptarmigan population
Authors: BRØSETH HENRIK , TUFTO JARLE , PEDERSEN HANS CHR. , STEEN HARALD , KASTDALEN LEIF
Published: June 2005

Harvest management requires knowledge of whether the harvest is sustainable as a result of compensatory mechanisms, such as dispersal. The effect of recreational harvesting on dispersal patterns in willow ptarmiganLagopus lagopuswas assessed over four hunting seasons in central Norway.

A two‐parameter Weibull model was fitted to the observed absolute dispersal distance data using maximum likelihood methods. Estimates of the scale and shape parameters for the dispersal probability distribution were calculated, describing the distribution of observed willow ptarmigan dispersal distances. From the parameter estimates of the dispersal model we estimated the standard deviation of the dispersal displacement relevant for population genetic and spatial population dynamic models.

The effect of harvesting on dispersal patterns was examined by testing for differences in the scale and shape parameters of dispersal distance distributions in areas with and without harvest. No effect of harvesting was found, either in adults or juveniles.

Breeding dispersal of adult birds was estimated as a dispersal probability distribution with scale parametera = 402 m and shape parameterb = 2·01, corresponding to a dispersal standard deviation of σ = 284 m. The dispersal probability distribution of adults was not significantly different from a bivariate normal distribution.

Natal dispersal had a dispersal probability distribution with scale parametera = 4206 m and shape parameterb = 1·16, corresponding to a dispersal standard deviation σ = 3728 m. The dispersal probability distribution of juveniles was not significantly different from an exponential distribution.

Synthesis and applications. Reduction of the population density of willow ptarmigan through harvesting at moderate densities does not seem to affect the dispersal distances. Thus, if there is little or no difference in the dispersal probability distribution in harvested and non‐harvested areas there will be only weak or no compensation for the harvest, given that natural mortality and reproduction is the same in both areas. Thus, erroneously assuming compensation of harvest by immigration into a local population can lead to overharvest.
REVIEW: Questionnaires in ecology: a review of past use and recommendations for best practice
Authors: WHITE PIRAN C. L. , JENNINGS NANCY VAUGHAN , RENWICK ANNA R. , BARKER NOLA H. L.
Published: June 2005

Questionnaires, or social surveys, are used increasingly as a means of collecting data in ecology. We present a critical review of their use and give recommendations for good practice.

We searched for papers in which questionnaires were used in 57 ecological academic journals, published over the period 1991–2003 inclusive. This provided a total sample size of 168 questionnaires from 127 papers published in 22 academic journals.

Most questionnaires were carried out in North America and western Europe, and addressed species‐level issues, principally focusing on mammals. The majority were concerned with impacts of species and/or their conservation, and just under half with human–wildlife interactions.

Postal survey was the method used most frequently to carry out the questionnaires, followed by in‐person interviews. Some questionnaires were conducted by telephone, and none was web‐based.

Most questionnaires were concerned with obtaining factual information or perceptions of facts. Ground‐truthing (independent verification of the facts) was carried out in less than 10% of questionnaires.

The mean (± SE) sample size (number of respondents) per questionnaire was 1422 ± 261 and the average (± SE) response rate was 63 ± 3%. These figures varied widely depending on the methods used to conduct the questionnaire.

The analysis of data was mostly descriptive. Simple univariate methods were the most frequently used statistical tools, and data from a third of questionnaires were not subjected to any analysis beyond simple descriptions of the results.

Synthesis and applications.We provide recommendations for best practice in the future use of questionnaires in ecology, as follows: (i) the definition of the target population, any hypotheses to be tested and procedures for the selection of participants should be clearly documented; (ii) questionnaires should be piloted prior to their use; (iii) the sample size should be sufficient for the statistical analysis; (iv) the rationale for the choice of survey method should be clearly stated; (v) the number of non‐respondents should be minimized; (vi) the question and answer format should be kept as simple as possible; (vii) the structure of the questionnaire and the data emerging from it should be unambiguously shown in any publication; (viii) bias arising from non‐response should be quantified; (ix) the accuracy of data should be assessed by ground‐truthing where relevant; (x) the analysis of potentially interrelated data should be done by means of modelling. Researchers should also consider whether alternative, interpretative methods, such as in‐depth interviews or participatory approaches, may be more appropriate, for example where the focus is on elucidating motivations or perceptions rather than testing factual hypotheses.
Litterfall and nitrogen cycling following invasion byChrysanthemoides moniliferassp.rotundatain coastal Australia
Authors: LINDSAY ELIZABETH A. , FRENCH KRISTINE
Published: June 2005

On the south‐east coast of Australia there are extensive infestations of the environmental weed bitou bushChrysanthemoides moniliferassp.rotundata. This exotic weed is highly invasive and persistent, yet little is known about its impacts and how it dominates coastal vegetation.

A field study was carried out with sites selected for having an area heavily invaded byC. moniliferaand an uninvaded native shrubland area. The mass and components of the litterfall and ground litter layer were monitored and compared over 12 months. Nutrient analysis was performed on the abscised leaves and mature green leaves. Soil properties and nitrogen content were also examined.

There was a greater input of litter to the native areas (4800 ± 450 kg ha−1), which was highly seasonal, compared with theC. moniliferaareas (1690 ± 150 kg ha−1). There was also a greater mass of litter on the ground in the native areas (9600 ± 560 kg ha−1) thanC. moniliferaareas (3750 ± 170 kg ha−1), probably as a result of the higher leaf fall rate and slow decomposition rate.

A large proportion of nutrients was withdrawn from the native (48–80%) andC. moniliferaleaves (38–60%) before abscission. The litterfall was estimated to contain more than twice the amount of nitrogen and phosphorous within the native areas, because of the high leaf fall rate rather than a high nutrient content.

The total soil nitrogen was two to five times higher in the invaded areas (average 2570 ± 620 kg ha−1) than within the native areas (730 ± 90 kg ha−1). This was accompanied by an increase in ammonia content. The bulk density was lower in invaded areas, but there was no clear trend in the change in soil pH.

Synthesis and applications.The higher soil nitrogen beneath the weed infestations could increase the competitive superiority ofC. moniliferadirectly by increasing growth rate, or indirectly by impairing the establishment of native species that are adapted to growing in nutrient‐poor soils. The control technique of sprayingC. moniliferawith herbicide, then burning and spraying seedlings again, could lead to greater regeneration success for natives species than sprayingC. moniliferawith herbicide only.
METHODOLOGICAL INSIGHTS: Increasing the value of principal components analysis for simplifying ecological data: a case study with rivers and river birds
Authors: VAUGHAN I. P. , ORMEROD S. J.
Published: June 2005

Two priorities for applied ecologists are to (i) maintain quantitative rigour with minimal resources and (ii) ensure that multivariate results are readily understood by end users. Habitat descriptions and other complex data present particular challenges.

Principal components analysis (PCA) is often used to reduce data and stabilize subsequent statistical analyses. Interpretation can be difficult, however, and PCA is optimized for quantitative (cf. categorical) data. Moreover, future applications (e.g. in predicting species’ distributions) require the recording of all contributing variables irrespective of cost or importance.

We considered the potential benefits of two PCA variants. First, we considered whether a cluster analysis on the correlation matrix of independent variables (i.e. variable clustering), followed by a PCA within each cluster, produced a more easily interpreted output than conventional PCA, while simultaneously reducing costs. Secondly, we considered whether a generalized PCA capable of analysing qualitative data could out‐perform conventional PCA when ecological data include ordinal variables. As a case study, we used data from river habitat survey (RHS), a key applied tool in river ecology that uses more than 100 variables to describe river structure and relies heavily on three‐point ordinal scales. In distribution models that linked river birds to RHS, we compared the interpretability and efficiency of variable clustering and generalized PCA against conventional PCA.

While variable clustering gave similar predictive performance to PCA, habitat factors generated by the former were more readily interpreted than conventional principal components. Of the two cluster‐scoring methods, optimally scaled PCA explained 24% more variance in the first principal component and marginally improved the accuracy of distribution models.

Synthesis and applications. Initial variable clustering makes PCA more interpretable and will benefit the understanding of research results and their translation into management. Variable clustering should also reduce costs as variables contributing to unused clusters need not be recorded in future (cf. PCA). Optimal scaling further increases the versatility of PCA: qualitative ecological data (e.g. habitat categories) can be analysed in the same way as quantitative data, with real benefits to applied research. With cost constraints and the need for dissemination key applied issues, our results offer an important potential advance.
Modelling wildebeest population dynamics: implications of predation and harvesting in a closed system
Authors: TAMBLING CRAIG J. , DU TOIT JOHAN T.
Published: June 2005

Predation upon ungulates is generally considered to have a stronger regulatory effect on sedentary than migratory populations, with migratory populations maintaining higher densities. The blue wildebeest Connochaetus taurinus is a migratory species that has suffered a general decline in numbers and distribution across its species range. Wildebeest suffer from a fragmented distribution together with isolation of populations in closed reserves, preventing migratory movements and potentially allowing predators to benefit from a ‘captive’ prey resource.

In Pilanesberg National Park, South Africa, the declining blue wildebeest population (from 1074 in 1995 to 594 in 2001) is sedentary because the park (50 000 ha) is completely enclosed by fencing. This population was used to model the potential effects of predation and harvesting. The Pilanesberg population was then compared with other wildebeest populations in southern Africa.

The model outputs demonstrated that increased levels of predation by lions Panthera leo on a ‘captive’ population of prey such as wildebeest, in combination with regular harvesting by park managers, can drive the population towards extinction. At lower levels of predation some other factor needs to act in combination with predation to drive the population into a decline.

During our study the lion biomass density in Pilanesberg was almost three times greater than that predicted by regression models of the stable relationship between lion and prey biomass densities across African savannas. Furthermore, the ratio of lion numbers to prey numbers was substantially higher than in most other African reserves.

Synthesis and applications. In African savannas, artificial closed systems provide advantages to large predators. If wildlife‐cropping schemes are implemented in such systems without careful monitoring and regulation of large predators, then ungulate populations can decline more rapidly than managers expect.
METHODOLOGICAL INSIGHTS: Using seismic sensors to detect elephants and other large mammals: a potential census technique
Authors: WOOD JASON D. , O'CONNELL‐RODWELL CAITLIN E. , KLEMPERER SIMON L.
Published: June 2005

Large mammal populations are difficult to census and monitor in remote areas. In particular, elephant populations in Central Africa are difficult to census due to dense forest, making aerial surveys impractical. Conservation management would be improved by a census technique that was accurate and precise, did not require large efforts in the field, and could record numbers of animals over a period of time.

We report a new detection technique that relies on sensing the footfalls of large mammals. A single geophone was used to record the footfalls of elephants and other large mammal species at a waterhole in Etosha National Park, Namibia.

Temporal patterning of footfalls is evident for some species, but this pattern is lost when there is more than one individual present.

We were able to discriminate between species using the spectral content of their footfalls with an 82% accuracy rate.

An estimate of the energy created by passing elephants (the area under the amplitude envelope) can be used to estimate the number of elephants passing the geophone. Our best regression line explained 55% of the variance in the data. This could be improved upon by using an array of geophones.

Synthesis and applications. This technique, when calibrated to specific sites, could be used to census elephants and other large terrestrial species that are difficult to count. It could also be used to monitor the temporal use of restricted resources, such as remote waterholes, by large terrestrial species.