bluuebunny/crossref_metadata_2025 huggingface dataset:
Ventilator-associated Pneumonia Leading to Acute Lung Injury after Trauma
Authors: Stéphan François , Mabrouk Nejma , Decailliot François , Delclaux Christophe , Legrand Patrick
Published: January 2006

Background

Ventilator-associated pneumonia is a clear risk factor for acute lung injury which has been poorly described in trauma patients. This prospective study was undertaken to estimate the incidence of such ventilator-associated pneumonia leading to acute lung injury, the risk factors, and the associated morbidity and mortality in a group of multiple trauma patients.

Methods

Trauma patients who were mechanically ventilated and survived at least 24 h were included. Ventilator-associated pneumonia was confirmed by a bacterial culture of a blind protected telescoping catheter with at least 10 colony-forming units/ml of at least one pathogen. Episodes of acute lung injury were prospectively recorded.

Results

Ventilator-associated pneumonia was documented in 78 patients of the 175 included (44%) and led to the development of ventilator-associated pneumonia acute lung injury in 18 patients (23%). The sole independent risk factor for ventilator-associated pneumonia leading to acute lung injury was the presence of Haemophilus influenzae (hazard ratio, 8.8; 95% confidence interval, 2.7-28.6). Eleven (61%) of the 18 patients with ventilator-associated pneumonia leading to acute lung injury had development of a ventilator-associated pneumonia recurrence, as compared with 20 (33%) of the 60 patients with ventilator-associated pneumonia alone (P = 0.03). Seven (39%) of the 18 trauma patients with ventilator-associated pneumonia leading to acute lung injury died, as compared with 9 (15%) of the 60 trauma patients with ventilator-associated pneumonia alone (P = 0.04).

Conclusion

Acute lung injury complicated the course of 15% of ventilator-associated pneumonia in trauma patients. H. influenzae seemed to be one of the most frequent bacteria involved and the sole risk factor identified. Occurrence of ventilator-associated pneumonia leading to acute lung injury modified the prognosis of trauma patients.
Intrapatient Reproducibility of the BISxp® Monitor
Authors: Niedhart Dagmar J. , Kaiser Heiko A. , Jacobsohn Eric , Hantler Charles B. , Evers Alex S. , Avidan Michael S.
Published: January 2006

Background

The Bispectral Index (BIS) reportedly reflects anesthetic depth. It is recommended that anesthetic agents should be titrated to maintain the BIS between 40 and 60 arbitrary BIS units during anesthesia. For anesthesia providers to follow this recommendation, the monitor should be predictably affected by different anesthetic agents and have good interpatient and intrapatient reproducibility. The authors hypothesized that when two BISxp devices (Aspect Medical Systems, Newton, MA) are placed concurrently on the same patient, their readings are concordant throughout the anesthetic period.

Methods

Simultaneous BIS recordings from two BISxp monitors were obtained during anesthesia at 5-s intervals from 12 participants.

Results

In total 22,860 concurrent paired BIS readings were obtained. For 10.7% of the time, there were sustained periods of 30 s or greater where the readings suggested a different depth of anesthesia. For 6% of the time, there were sustained periods of 30 s or greater where the readings differed by 10 or more arbitrary BIS units. The regression coefficient (R) for the two devices was 0.65 (range, 0.35-0.92). There was zero bias between the devices, and the 95% limits of agreement ranged between -18 and +17.

Conclusion

A conflicting anesthetic management was suggested by the simultaneous BIS readings 10.7% of the time. These results suggest that BISxp does not always provide a reproducible single number. Anesthesia providers should not rely exclusively on the BIS reading when assessing depth of anesthesia.
Comparative Effects of Vaporized Perfluorohexane and Partial Liquid Ventilation in Oleic Acid– induced Lung Injury
Authors: de Abreu Marcelo Gama , Quelhas André Domingues , Spieth Peter , Bräuer Götz , Knels Lilla , Kasper Michael , Pino Alexandre Visintainer , Bleyl Jörg-Uwe , Hübler Matthias , Bozza Fernando , Salluh Jorge , Kuhlisch Eberhard , Giannella-Neto Antonio , Koch Thea
Published: January 2006

Background

It is currently not known whether vaporized perfluorohexane is superior to partial liquid ventilation (PLV) for therapy of acute lung injury. In this study, the authors compared the effects of both therapies in oleic acid-induced lung injury.

Methods

Lung injury was induced in 30 anesthetized and mechanically ventilated pigs by means of central venous infusion of oleic acid. Animals were assigned to one of the following groups: (1) control or gas ventilation (GV), (2) 2.5% perfluorohexane vapor, (3) 5% perfluorohexane vapor, (4) 10% perfluorohexane vapor, or (5) PLV with perfluorooctane (30 ml/kg). Two hours after randomization, lungs were recruited and positive end-expiratory pressure was adjusted to obtain minimal elastance. Ventilation was continued during 4 additional hours, when animals were killed for lung histologic examination.

Results

Gas exchange and elastance were comparable among vaporized perfluorohexane, PLV, and GV before the open lung approach was used and improved in a similar fashion in all groups after positive end-expiratory pressure was adjusted to optimal elastance (P < 0.05). A similar behavior was observed in functional residual capacity (FRC) in animals treated with vaporized perfluorohexane and GV. Lung resistance improved after recruitment (P < 0.05), but values were higher in the 10% perfluorohexane and PLV groups as compared with GV (P < 0.05). Interestingly, positive end-expiratory pressure values required to obtain minimal elastance were lower with 5% perfluorohexane than with PLV and GV (P < 0.05). In addition, diffuse alveolar damage was significantly lower in the 5% and 10% perfluorohexane vapor groups as compared with PLV and GV (P < 0.05).

Conclusions

Although the use of 5% vaporized perfluorohexane permitted the authors to reduce pressures needed to stabilize the lungs and was associated with better histologic findings than were PLV and GV, none of these perfluorocarbon therapies improved gas exchange or lung mechanics as compared with GV.
Sonographic Visualization and Ultrasound-guided Block of the Third Occipital Nerve
Authors: Eichenberger Urs , Greher Manfred , Kapral Stephan , Marhofer Peter , Wiest Roland , Remonda Luca , Bogduk Nikolai , Curatolo Michele
Published: January 2006

Background

Chronic neck pain after whiplash injury is caused by cervical zygapophysial joints in 50% of patients. Diagnostic blocks of nerves supplying the joints are performed using fluoroscopy. The authors' hypothesis was that the third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique.

Methods

In 14 volunteers, the authors placed a needle ultrasound-guided to the third occipital nerve on both sides of the neck. They punctured caudal and perpendicular to the 14-MHz transducer. In 11 volunteers, 0.9 ml of either local anesthetic or normal saline was applied in a randomized, double-blind, crossover manner. Anesthesia was controlled in the corresponding skin area by pinprick and cold testing. The position of the needle was controlled by fluoroscopy.

Results

The third occipital nerve could be visualized in all subjects and showed a median diameter of 2.0 mm. Anesthesia was missing after local anesthetic in only one case. There was neither anesthesia nor hyposensitivity after any of the saline injections. The C2-C3 joint, in a transversal plane visualized as a convex density, was identified correctly by ultrasound in 27 of 28 cases, and 23 needles were placed correctly into the target zone.

Conclusions

The third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique. The needles were positioned accurately in 82% of cases as confirmed by fluoroscopy; the nerve was blocked in 90% of cases. Because ultrasound is the only available technique today to visualize this nerve, it seems to be a promising new method for block guidance instead of fluoroscopy.
Ultrasound Examination and Localization of the Sciatic Nerve
Authors: Chan Vincent W. S. , Nova Hugo , Abbas Sherif , McCartney Colin J. L. , Perlas Anahi , Quan Xu Da
Published: January 2006

Background

Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods

In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results

The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.

Conclusions

These preliminary data show that a curved 2- to 5-MHz ultrasound probe provides good quality sciatic nerve imaging in the gluteal, infragluteal, and proximal thigh locations. Ultrasound-assisted sciatic nerve localization is potentially valuable for clinical sciatic nerve blocks.
Reduction of Verbal Pain Scores after Anterior Cruciate Ligament Reconstruction with 2-Day Continuous Femoral Nerve Block
Authors: Williams Brian A. , Kentor Michael L. , Vogt Molly T. , Irrgang James J. , Bottegal Matthew T. , West Robin V. , Harner Christopher D. , Fu Freddie H. , Williams John P.
Published: January 2006

Background

Single-injection femoral nerve block analgesia and spinal anesthesia have been associated with fewer postoperative nursing interventions and successful same-day discharge after anterior cruciate ligament reconstruction. In the current study, the authors prospectively determined the effect of continuous femoral nerve block on a numeric rating scale (NRS) of pain intensity with movement for 7 postoperative days.

Methods

Patients undergoing this surgery with no history of previous invasive surgery on the same knee were recruited for this study. After standardized spinal anesthesia, intravenous sedation, and perioperative multimodal analgesia, patients received a femoral nerve catheter with (1) saline bolus (30 ml) plus saline infusion (270 ml at 5 ml/h, placebo group); (2) levobupivacaine (0.25%) bolus with saline infusion (group I), or (3) levobupivacaine (0.25%) bolus and infusion (group II). Patients were surveyed preoperatively and on postoperative days 1-4 and 7 to determine NRS scores (scale 0-10).

Results

Data from 233 participants were analyzed. On days 1-2, 50% of placebo patients had NRS scores of 5 or above, whereas among group II patients, only 25% had scores of 5 or above (P < 0.001). In regression models for NRS scores during days 1-4, group II was the only factor predicting lower pain scores (odds ratios, 0.3-0.5; P = 0.001-0.03). Overall, patients with preoperative NRS scores greater than 2 were likely to report higher NRS scores during days 1-7 (odds ratios, 3.3-5.2; P < 0.001).

Conclusions

Femoral nerve block catheters reliably keep NRS scores below the moderate-to-severe pain threshold for the first 4 days after anterior cruciate ligament reconstruction.
Actions of Midazolam on Excitatory Transmission in Dorsal Horn Neurons of Adult Rat Spinal Cord
Authors: Kohno Tatsuro , Wakai Ayako , Ataka Toyofumi , Ikoma Miho , Yamakura Tomohiro , Baba Hiroshi
Published: January 2006

Background

Although intrathecal administration of midazolam, a water-soluble imidazobenzodiazepine derivative, has been found to produce analgesia, how it exerts this effect at the neuronal level in the spinal cord is not fully understood.

Methods

The effects of midazolam on electrically evoked and spontaneous excitatory transmission were examined in lamina II neurons of adult rat spinal cord slices using the whole cell patch clamp technique.

Results

Bath-applied midazolam (1 microm) diminished Adelta- and C-fiber evoked polysynaptic excitatory postsynaptic currents in both amplitude and integrated area. However, it affected neither Adelta- and C-fiber evoked monosynaptic excitatory postsynaptic currents in amplitude nor miniature excitatory postsynaptic currents in amplitude, frequency, and decay time constant. In the presence of a benzodiazepine receptor antagonist, flumazenil (5 microm), midazolam (1 microm) did not diminish Adelta-fiber evoked polysynaptic excitatory postsynaptic currents, suggesting that midazolam modulate the gamma-aminobutyric acid interneurons in the dorsal horn.

Conclusions

Midazolam reduced excitatory synaptic transmission by acting on the gamma-aminobutyric acid type A/benzodiazepine receptor in interneurons, leading to a decrease in the excitability of spinal dorsal horn neurons. This may be a possible mechanism for the antinociception by midazolam in the spinal cord.
Perineural Clonidine Reduces Mechanical Hypersensitivity and Cytokine Production in Established Nerve Injury
Authors: Romero-Sandoval Alfonso , Eisenach James C.
Published: January 2006

Background

Partial sciatic nerve ligation (PSNL) produces axonal damage, a local inflammatory response, and wallerian degeneration. Cytokines secreted near the site of nerve injury are thought to play important roles in development and maintenance of central sensitization and neuropathic pain. Injection of clonidine at the site and time of nerve injury slows the development of PSNL-induced hypersensitivity and reduces local cytokine expression by actions on alpha2 adrenoceptors. The current study tested whether clonidine would have a similar effect in established nerve injury.

Methods

Rats underwent unilateral PSNL, and perineural saline, clonidine, or BRL44408 plus clonidine was injected 2 weeks later. Three days after perineural injection, withdrawal threshold to mechanical stimulation of the hind paw ipsilateral and contralateral to PSNL was determined, and tissues were removed for cytokine analysis.

Results

PSNL was accompanied by a proinflammatory pattern of cytokine content in neural structures and hypersensitivity ipsilaterally with few changes contralaterally. Perineural clonidine, but not saline, partially reversed the hypersensitivity, accompanied by reduced concentrations of interleukin 6 and interleukin 1beta in the sciatic nerve. The effect of clonidine on hypersensitivity and these cytokines was blocked by the alpha2-adrenoceptor antagonist, BRL44408.

Conclusions

These data suggest that perineural clonidine acts on alpha2 adrenoceptors to reduce hypersensitivity in established nerve injury, likely by an immunomodulatory mechanism, and may be effective in patients in the weeks after nerve injury.
Integrated mechanistic and data-driven modelling for multivariate analysis of signalling pathways
Authors: Hua Fei , Hautaniemi Sampsa , Yokoo Rayka , Lauffenburger Douglas A
Published: January 2006

Mathematical models of highly interconnected and multivariate signalling networks provide useful tools to understand these complex systems. However, effective approaches to extracting multivariate regulation information from these models are still lacking. In this study, we propose a data-driven modelling framework to analyse large-scale multivariate datasets generated from mathematical models. We used an ordinary differential equation based model for the Fas apoptotic pathway as an example. The first step in our approach was to cluster simulation outputs generated from models with varied protein initial concentrations. Subsequently, decision tree analysis was applied, in which we used protein concentrations to predict the simulation outcomes. Our results suggest that no single subset of proteins can determine the pathway behaviour. Instead, different subsets of proteins with different concentrations ranges can be important. We also used the resulting decision tree to identify the minimal number of perturbations needed to change pathway behaviours. In conclusion, our framework provides a novel approach to understand the multivariate dependencies among molecules in complex networks, and can potentially be used to identify combinatorial targets for therapeutic interventions.
Max Perutz: chemist, molecular biologist, human rights activist
Authors: Thomas John Meurig
Published: January 2006

Tribute paid to Max Perutz before the Max Perutz Memorial Lecture given by Professor Sari Nusseibeh at The International Human Rights Network of Academics and Scholarly Societies, The Royal Society, London, 19 May 2005.
VP1 sequences of German porcine parvovirus isolates define two genetic lineages
Authors: Zimmermann P. , Ritzmann M. , Selbitz H.-J. , Heinritzi K. , Truyen U.
Published: January 2006

In order to evaluate the genetic variability of Porcine parvovirus (PPV), the complete capsid protein sequences (VP1/VP2) from seven recent field isolates from Germany, one isolate from the UK and one German vaccine strain were sequenced and analysed, along with two American (NADL-2 and Kresse), three Asian and 22 Brazilian partial PPV sequences retrieved from GenBank. The analysis revealed a high degree of diversity: 1·2–2·6 % at the nucleotide level and 1·2–6·8 % at the amino acid level. Phylogenetic analysis defined two German clusters: one formed by four German isolates and the English, Asian and American sequences; and the second, distinct cluster formed by the other three of the seven German isolates examined. The latter cluster was still observed when the 22 partial sequences (853 nt of the 3′ terminus of the VP2 gene) from the Brazilian isolates were included in the analyses, indicating that the VP2 sequence determines the phylogeny.
Characterization and transcriptional analysis of protein tyrosine phosphatase genes and an ankyrin repeat gene of the parasitoid Glyptapanteles indiensis polydnavirus in the parasitized host
Authors: Gundersen-Rindal D. E. , Pedroni M. J.
Published: January 2006

Glyptapanteles indiensis (Braconidae, Hymenoptera) is an endoparasitoid of Lymantria dispar, the gypsy moth. Expression of G. indiensis polydnavirus (GiBV)-encoded genes within the pest host results in inhibition of immune response and development and alteration of physiology, enabling successful development of the parasitoid. Here, GiBV genome segment F (segF), an 18·6 kb segment shown to encode nine protein tyrosine phosphatase (PTP) genes and a single ankyrin repeat gene (ank), is analysed. PTPs have presumed function as regulators of signal transduction, while ankyrin repeat genes are hypothesized to function in inhibition of NF-κB signalling in the parasitized host. In this study, transcription of each gene was mapped by 5′- and 3′-RACE (rapid amplification of cDNA ends) and temporal and tissue-specific expression was examined in the parasitized host. For polydnavirus gene prediction in the parasitized host, no available gene prediction parameters were entirely precise. The mRNAs for each GiBV segF gene initiated between 30 and 112 bp upstream of the translation initiation codon. All were encoded in single open reading frames (ORFs), with the exception of PTP9, which was transcribed as a bicistronic message with the adjacent ank gene. RT-PCR indicated that all GiBV segF PTPs were expressed early in parasitization and, for most, expression was sustained over the course of at least 7 days after parasitization, suggesting importance in both early and sustained virus-induced immunosuppression and alteration of physiology. Tissue-specific patterns of PTP expression of GiBV segF genes were variable, suggesting differing roles in facilitating parasitism.
Characterization of the N-terminal domain of classical swine fever virus RNA-dependent RNA polymerase
Authors: Xiao Ming , Li Huaibo , Wang Yujing , Wang Xiaohui , Wang Wei , Peng Jun , Chen Jiakuan , Li Bo
Published: January 2006

To investigate RNA-dependent RNA polymerase (RdRp) further, mutational analysis of the N-terminal domain of the NS5B protein of Classical swine fever virus was performed. Results show that the N-terminal domain (positions 1–300) of the protein might be divided artificially into four different regions, N1–N4. The N1 region (positions 1–61) contained neither conserved lysine nor conserved arginine residues. NS5B protein with deletion of the N1 region has the capacity for elongative RNA synthesis, but not for de novo RNA synthesis on natural templates. All substitutions of the conserved lysines and arginines in the N2 region (positions 63–216) destroyed RdRp activity completely. Substitutions of the conserved arginines in the N3 region (positions 217–280) seriously reduced RdRp activity. However, all substitutions of the conserved lysines in this region enhanced RNA synthesis and made the mutants synthesize RNA on any template. Substitutions of the conserved arginines in the N4 region (positions 281–300) reduced elongative synthesis and destroyed de novo RNA synthesis. In contrast, substitutions of lysines in this region did not affect RdRp activity significantly. These data indicate that the N3 region might be related to the enzymic specificity for templates, and the conserved lysines and arginines in different regions have different effects on RdRp activity. In combination with the published crystal structure of bovine viral diarrhea virus NS5B, these results define the important role of the N-terminal domain of NS5B for template recognition and de novo RNA synthesis.
Human immunodeficiency virus types 1 and 2 have different replication kinetics in human primary macrophage culture
Authors: Marchant David , Neil Stuart J. D. , McKnight Áine
Published: January 2006

This study compares the replication of primary isolates of human immunodeficiency virus type 2 (HIV-2) and type 1 (HIV-1) in monocyte-derived macrophages (MDMs). Eleven HIV-2 and five HIV-1 primary isolates that use CCR5, CXCR4 or both coreceptors to enter cells were included. Regardless of coreceptor preference, 10 of 11 HIV-2 viruses could enter, reverse transcribe and produce fully infectious virus in MDMs with efficiency equal to that in peripheral blood mononuclear cells. However, the kinetics of replication of HIV-2 compared with HIV-1 over time were distinct. HIV-2 had a burst of virus replication 2 days after infection that resolved into an apparent ‘latent state’ at day 3. HIV-1, however, continued to produce infectious virions at a lower, but steady, rate throughout the course of infection. These results may have implications for the lower pathogenesis and viral-load characteristics of HIV-2 infection.
The mitochondrial pathway of apoptosis is triggered during feline calicivirus infection
Authors: Natoni Alessandro , Kass George E. N. , Carter Michael J. , Roberts Lisa O.
Published: January 2006

Feline calicivirus (FCV) belongs to the family Caliciviridae and is an important pathogen of the upper respiratory tract of cats. Recent studies have shown that cells infected with FCV undergo apoptosis, as evidenced by caspase activation, chromatin condensation and cleavage of poly(ADP-ribose) polymerase. Here, the upstream events were investigated in order to define the molecular mechanism of apoptosis in FCV-infected cells. It was shown that FCV induced translocation of phosphatidylserine to the cell outer membrane and release of cytochrome c from mitochondria at about 6–8 h post-infection. These events were preceded by the loss of mitochondrial membrane potential and Bax translocation from the cytosol to mitochondria between 4 and 6 h after infection. Release of cytochrome c from mitochondria triggered the activation of caspase-9 and the subsequent activation of the executioner caspase, caspase-3. These results suggest that the mitochondrial pathway of apoptosis is triggered during FCV infection.
Influence of naturally occurring insertions in the fingers subdomain of human immunodeficiency virus type 1 reverse transcriptase on polymerase fidelity and mutation frequencies in vitro
Authors: Curr Kenneth , Tripathi Snehlata , Lennerstrand Johan , Larder Brendan A. , Prasad Vinayaka R.
Published: January 2006

The fingers subdomain of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is a hotspot for nucleoside analogue resistance mutations. Some multi-nucleoside analogue-resistant variants contain a T69S substitution along with dipeptide insertions between residues 69 and 70. This set of mutations usually co-exists with classic zidovudine-resistance mutations (e.g. M41L and T215Y) or an A62V mutation and confers resistance to multiple nucleoside analogue inhibitors. As insertions lie in the vicinity of the dNTP-binding pocket, their influence on RT fidelity was investigated. Commonly occurring insertion mutations were selected, i.e. T69S-AG, T69S-SG and T69S-SS alone, in combination with 3′-azido-2′,3′-deoxythymidine-resistance mutations M41L, L210W, R211K, L214F, T215Y (LAGAZand LSGAZ) or with an alternate set where A62V substitution replaces M41L (VAGAZ, VSGAZand VSSAZ). Using alacZαgapped duplex substrate, the forward mutation frequencies of recombinant wild-type and mutant RTs bearing each of the above sets of mutations were measured. All of the mutants displayed significant decreases in mutation frequencies. Whereas the dipeptide insertions alone showed the least decrease (4·0- to 7·5-fold), the VAG series showed an intermediate reduction (5·0- to 11·4-fold) and the LAG set showed the largest reduction in mutation frequencies (15·3- and 16·3-fold for LAGAZand LSGAZ, respectively). Single dNTP exclusion assays for mutants LSGAZand LAGAZconfirmed their large reduction in misincorporation efficiencies. The increasedin vitrofidelity was not due to excision of the incorrect nucleotide via ATP-dependent removal. There was also no direct correlation between increased fidelity and template–primer affinity, suggesting a change in the active site that is conducive to better discrimination during dNTP insertion.
Identification and immuno-electron microscopy localization of p40, a protein component of immunosuppressive virus-like particles from Leptopilina heterotoma, a virulent parasitoid wasp of Drosophila
Authors: Chiu Hsiling , Morales Jorge , Govind Shubha
Published: January 2006

Lamellocytes are specialized larval blood cells of Drosophila that carry out encapsulation of metazoan pathogens such as parasitoid wasps. Large virus-like particles (VLPs) from two closely related virulent parasitoid wasp species, Leptopilina heterotoma and Leptopilina victoriae, suppress the host encapsulation response by promoting lysis of lamellocytes. The molecular basis of VLP–lamellocyte interaction and lamellocyte lysis is not understood. Here, it was shown that mature VLPs are composed of at least four major proteins. Polyclonal antisera against the most abundant L. heterotoma VLP protein, p40, cross-reacted with the most abundant L. victoriae VLP protein, p47.5. Immuno-electron microscopy (EM) of the long gland–reservoir complex revealed that p40 was expressed early in VLP biogenesis and was detected along with VLP precursors within the long gland cells and lumen. In the reservoir, VLPs had an angular core, resembled mature particles and p40 was detected outside the VLP cores. Immuno-EM staining of mature VLPs from both species localized the p40 and p47.5 proteins largely to the periphery of the VLPs and along the VLP spike-like projections. p40 staining was observed in VLP-treated host haemocytes. In vitro, anti-p40 antibody almost completely blocked the ability of L. heterotoma VLPs to promote lamellocyte lysis. Anti-p40 antibody blocked lysis by L. victoriae VLPs by >50 %. It is proposed that the VLP surface proteins p40 and p47.5 share antigenic determinants and significantly contribute to the strong virulence of their Hymenopteran hosts.
Biological properties of Beet mild yellowing virus derived from a full-length cDNA clone
Authors: Stephan Dirk , Maiss Edgar
Published: January 2006

A German isolate ofBeet mild yellowing virus(BMYV-IPP) was used for RT-PCR-based construction of the first infectious full-length cDNA clone of the virus (BMYVfl). The complete genomic sequence was determined and displayed high similarity to the French isolate BMYV-2ITB. The host range of BMYVflwas examined by agroinoculation and aphid transmission. Both methods lead to systemic infections inBeta vulgaris,Nicotiana benthamiana,N. clevelandii,N. hesperis,Capsella bursa-pastorisandLamium purpureum. Immunological investigation by tissue-print immunoassay (TPIA) of agroinoculated plant tissues revealed only local infections restricted to the agroinoculated mesophyll tissues in some plant species. InNicotiana glutinosaandN. edwardsonii, BMYV was not found in either the agroinoculated tissue or distant tissues by TPIA. So far, BMYVflagroinoculation did not extend or confine the BMYV host range known from aphid transmission experiments but it did describe new local hosts for BMYV.
The use of a flexible patch leaving rule under exploitative competition: a field test with swans
Authors: Nolet Bart A. , Klaassen Raymond H. G. , Mooij Wolf M.
Published: January 2006

Learning animals are predicted to use a flexible patch‐leaving threshold (PLT) while foraging in a depletable environment under exploitative competition. This prediction was tested in flock‐feeding Bewick's swans (Cygnus columbianus bewickii) depleting hidden tubers of fennel pondweed (Potamogeton pectinatus) in a two‐dimensional, continuous environment. The swans' patch residence time was measured by combining recordings of the foraging behaviour and movement paths. The tuber biomass density was measured before and after the period of exploitation, using the presumable foraging window of the swans as the scale of measurement. Swan foraging was simulated in order to predict the effects of flexible and fixed PLTs, respectively, on the patch residence time and the spatial heterogeneity of the tuber biomass density. Flexible PLTs were predicted to lead to short and decreasing patch residence times and a decrease in the coefficient of variation in tuber biomass densities, whereas the reverse was generally the case for fixed PLTs. Observed patch residence times did not decrease with time and were intermediate between those predicted for swans with flexible and fixed PLTs. Furthermore, an increase of the coefficient of variation in the tuber biomass density was observed. Given the observed giving‐up biomass densities the most likely model was one with swans with a fixed rather than a flexible PLT. These results point at factors that may affect the spacing behaviour or constrain the use of a flexible PLT in swans.
Intake rate at differently scaled heterogeneous food distributions explained by the ability of tactile‐foraging mallard to concentrate foraging effort within profitable areas
Authors: H. G. Klaassen Raymond , A. Nolet Bart , De Fouw Jim
Published: January 2006

The ability to respond to spatial heterogeneity in food abundance depends on the scale of the food distribution and the foraging scale of the forager. The aim of this study is to illustrate that a foraging scale exists, and that at larger scaled food distributions foragers benefit from the ability to subdivide a continuous (non‐discrete) heterogeneous environment into profitable and non‐profitable areas. We recorded search patterns of mallards Anas plathyrhynchos foraging in shallow water on cryptic prey items (millet seeds), distributed at different scales. A small magnet attached to the lower mandible allowed us to record in great detail the position and movements of the bill tip within a feeding tray underlain by magnet sensors. Instantaneous intake rate was determined in a subsequent experiment. We successfully determined the foraging scale (about 2×2 cm), defined as the scale above which foragers do respond (coarse scaled distribution) and below which foragers do not respond (fine scaled distribution) to spatial heterogeneity, by concentrating foraging effort within areas of high food density. A response resulted in a significantly higher intake rate, compared to a homogeneous distribution with an equal overall density. Unlike systematic search cell revisitation was common in trials, and at coarse scaled food distributions even slightly (but significantly) more frequently observed than predicted for random search. Mallards respond to food capture by restricting displacement (area restricted search) at food distributions that are considered to be clumped for the forager (large scaled coarse distributions). We argue that partitioning the environment at the foraging scale in itself could be a mechanism to concentrate foraging efforts within profitable areas, because mallard were able to respond to heterogeneity at coarse scaled food distributions even when non‐clumped (i.e. without conducting area restricted search).
A simpler, more general method of finding the optimal foraging strategy for Bayesian birds
Authors: F. Green Richard
Published: January 2006

Oaten's (1977)stochastic model for optimal foraging in patches has been solved for a number of particular cases. A few cases, such as Poisson prey distribution and either systematic or random search, are easy to solve. In other cases, such as binomial prey distribution and random search, the form of the optimal strategy may be found using a theorem of McNamara, although more work is required to find which particular rule of the proper form is actually best. More generally (but not completely generally), optimal strategies may be found using dynamic programming. This requires that the number of prey found up to a particular time is a sufficient statistic for the number of prey remaining in a patch. This requirement cannot be dispensed with, but other simplifying assumptions that were used in the past are not necessary. In particular, it is not necessary, even for the sake of convenience, to assume that prey distribution has a form convenient for Bayesian analysis, such as a beta mixture of binomials or a gamma mixture of Poissons. Any prey distribution may be used if whatever prey are in a patch are located at random, and if search either is systematic for discrete time or for continuous time, or is random for continuous time. In earlier work, some pains had to be taken to find the rate of finding prey achieved by a given candidate strategy, but this is not necessary if expected gains and expected times are calculated routinely for each potential stopping point during dynamic programming. A new, simple method of finding optimal strategies is illustrated for discrete time and systematic search. This paper is based on a talk given at the Fifth Hans Kristiansson Symposium held in Lund, Sweden in August, 2003. The subject of the symposium was Bayesian foraging.
Foraging costs and accessibility as determinants of giving‐up densities in a swan‐pondweed system
Authors: Nolet Bart A. , Fuld Verinne N. , Van Rijswijk Marielle E.C.
Published: January 2006

We measured the patch use behaviour of Bewick's swans (Cygnus columbianus bewickii) feeding on below ground tubers of fennel pondweed (Potamogeton pectinatus). We compared the swans’ attack rates, foraging costs and giving‐up densities (GUDs) in natural and experimental food patches that differed in water depth. Unlike most studies that attribute habitat‐specific differences in GUDs to predation risk, food quality or foraging substrate, we quantified the relative importance of energetic costs and accessibility. Accessibility is defined as the extent to which the animal's morphology restricts its harvest of all food items within a food patch. Patch use behaviours were measured at shallow (ca 0.4 m) and deep (ca 0.6 m) water depths on sandy sediments. In a laboratory foraging experiment, when harvesting food patches, the swan's attack rate (m3 s−1) did not differ between depths. In deep water the energetic costs of surfacing, feeding and trampling were 1.13 to 1.21 times higher than in shallow water with a tendency to spend relatively more time trampling, the most expensive activity. Taking time allocation as measured in the field into account, foraging in deep water was 1.26 times as expensive as in shallow water. In the lake the GUD in shallow water was on average 12.9 g m−2. If differences in energetic costs were the only factor determining differences in GUDs, then the deep water GUD should be 14.2 g m−2. Instead, the mean GUD in deep water was 20.2 g m−2, and therefore energetic costs explain just 18% of the difference in GUDs. At deep sites, 24% of tuber biomass was estimated to be out of reach, and we calculated a maximum accessible foraging depth of 0.86 m. This is close to the published 0.84 m based on body measurements. A laboratory experiment with food offered at a depth of 0.89 m confirmed that it was just out of reach. The agreement between calculated and observed maximum accessible foraging depths suggests that accessibility largely explains the remaining difference in GUDs with depth, and it confirms the existence of partial prey refuges in this system.
The foraging benefits of information and the penalty of ignorance
Authors: Olsson Ola , S. Brown Joel
Published: January 2006

Patch use theory and the marginal value theorem predict that a foraging patch should be abandoned when the costs and benefits of foraging in the patch are equal. This has generally been interpreted as all patches being abandoned when their instantaneous intake rate equals the foraging costs. Bayesian foraging – patch departure is based on a prior estimate of patch qualities and sampling information from the current patch – predicts that instantaneous quitting harvest rates sometimes are not constant across patches but increase with search time in the patch. That is, correct Bayesian foraging theory has appeared incompatible with the widely accepted cost–benefit theories of foraging. In this paper we reconcile Bayesian foraging with cost–benefit theories. The general solution is that a patch should be left not when instantaneous quitting harvest rate reaches a constant level, but when potential quitting harvest rate does. That is, the forager should base its decision on the value now and in the future until the patch is left. We define the difference between potential and instantaneous quitting harvest rates as the foraging benefit of information, FBI. For clumped prey the FBI is positive, and by including this additional benefit of patch harvest the forager is able to reduce its penalty of ignorance.
Topological keystone species: measures of positional importance in food webs
Authors: Jordán Ferenc , Liu Wei‐chung , Davis Andrew J.
Published: January 2006

The local extinction or large fluctuation in abundance of a species may seriously affect other species in the community. The effects spread through the community by direct and indirect interactions. The network perspective on ecology can help map the pathways of these effects, for food webs, the pathways of indirect trophic interactions. Indirect interactions typically decay in intensity as they spread. Therefore, there is a conceptual maximum range in topological space beyond which interactions have no effects, even though all species remain connected. Neither the local characteristics of species, nor the global characteristics of entire webs, suitably quantify this range. We therefore apply intermediate scale indices that reflect the limitations imposed by effect damping in networks. We present a complex analysis of the topological positional importance of species in the Chesapeake Bay web. This web is a carbon‐flow network that represents trophic interactions. We present several different indices reflecting different properties and discuss which questions the different indices best answer. We look for the best indices for identifying the key players in ecosystem functioning. Our study contributes to the quantification of relative species importance and provides an exact and a priori determination of a class of candidate keystone species that can inform applied and conservation ecology as well as theoretical concerns.
Inter‐annual variation in herring, Clupea harengus, and sprat, Sprattus sprattus, condition in the central Baltic Sea: what gives the tune?
Authors: Casini Michele , Cardinale Massimiliano , Hjelm Joakim
Published: January 2006

The Baltic Sea ecosystem has undergone large changes during the last two decades, including a severe reduction in cod and herring biomass but, at the same time, a large increase in sprat abundance. The lower trophic levels of the Baltic Sea also changed due to environmental fluctuations, including variations in salinity and in volume of oxygenated water. In this apparently shifting environment, the conditions of herring and sprat have undergone large inter‐annual variations during the past 15–20 years. In this study, we explore how abiotic factors (i.e. salinity and temperature) and biotic factors (biomass of the copepods Pseudocalanus elongatus, Temora longicornis, Acartia spp. and of cladocerans as well as clupeid abundance) in different seasons (May and August) affect clupeid body condition. Our analyses suggest that data of zooplankton biomass and abiotic factors in August have higher predictive power than May data. Although our analysis suggests that salinity (a bottom‐up process) has an effect on sprat condition, total abundance of clupeids (a top‐down process) is by far the most significant predictor of both herring and sprat condition. The strong correlation between clupeid abundance and total zooplankton biomass points to food competition and to top‐down control by herring and sprat on common food resources. Furthermore, clupeid condition co‐varied with the changes in the weight of zooplankton in the stomachs, which further suggest food competition being the main mechanism behind the changes in clupeid condition during the last two decades. Hence, our results are not in agreement with most of the current literature that has suggested that clupeid growth is regulated by environmentally mediated bottom‐up processes acting on the abundance of copepods. This is, to our knowledge, the first evidence of food resources mediated density‐dependent fish growth in a large marine ecosystem.
Local vs regional factors as determinants of the invasibility of indigenous forest fragments by alien plant species
Authors: Ohlemüller Ralf , Walker Susan , Bastow Wilson J.
Published: January 2006

Both local and regional filters can determine the invasion of alien species into native plant communities. However, their relative importance is essentially unknown. We used plot data from fragments of indigenous forests in southeastern New Zealand to infer which factors are important in explaining invasibility, measured as alien species richness. Twenty‐eight predictor variables comprising both local factors (stand structure and soil) and regional ones (climate and land cover) were assessed. Reduction or increase in deviance in linear models was assessed, both individually and with a forward and backward stepwise variable selection procedure using the Akaike information criterion (AIC).

We found that higher alien species richness was mainly associated with forest fragments of small area in warm and dry climates and where there were only small areas of surrounding indigenous forest. Local soil and stand structure variables had considerably smaller effects on alien species richness than the regional land cover and climate variables. Alien species richness showed no relationship with native species richness. We conclude that in the forest fragments investigated here, of the variables included in the analyses, regional land cover and climate variables are potentially important drivers for alien species richness at plot level. This has implications for projections of alien species spread in the future under different climate change and land use scenarios.
Contrasting responses of bee communities to coffee flowering at different spatial scales
Authors: Veddeler Dorthe , Klein Alexandra‐Maria , Tscharntke Teja
Published: January 2006

While investigating biodiversity patterns on different spatial scales, ecological processes determining these patterns have been rarely analysed. Flower visitation by bees is an important ecological process that is related to floral resource availability. However, little is known about whether responses of bee communities to floral resource availability change at different spatial scales. We studied density and species richness of flower‐visiting bees in relation to floral resource availability, provided by coffee, in traditional agroforestry systems on a field, shrub, and branch scale. On a field scale, mean bee density per shrub increased with decreasing proportion of flowering coffee shrubs per site, showing a dilution effect. Conversely, on shrub and branch scales bee density per shrub, or shrub part, increased with increasing number of inflorescences, showing a concentration effect. Additionally, bee density per shrub was higher on those that were only partly, rather than totally surrounded by other flowering coffee shrubs. Species richness of flower‐visiting bees was positively affected by high resource availability on a shrub and a branch scale, expressed by a high number of inflorescences, but at the field scale the proportion of flowering shrubs per site did not have any effect on species richness. Our results show contrasting responses of the community of flower‐visiting bees to floral resource availability, depending on the spatial scale considered. We conclude that patterns of flower‐visiting bee communities of only one spatial scale can not be generalized, since the number of pollinators may be limited on a field scale, but not on smaller scales.
Estimating nutrient intake in comparative studies of animals: an example using dietary carotenoid content in birds
Authors: A. Olson Valérie
Published: January 2006

Many different methods of reporting animal diets have been used in ecological research. These vary greatly in level of accuracy and precision and therefore complicate attempts to measure and compare diets, and quantitites of nutrients in those diets, across a wide range of taxa. For most birds, the carotenoid content of the diet has not been directly measured. Here, therefore, I use an avian example to show how different methods of measuring the quantities of various foods in the diet affect the relative rankings of higher taxa (families, subfamilies, and tribes), and species within these taxa, with regard to the carotenoid contents of their diets. This is a timely example, as much recent avian literature has focused on the way dietary carotenoids may be traded off among aspects of survival, fitness and signalling. I assessed the mean dietary carotenoid contents of representatives of thirty higher taxa of birds using four different carotenoid intake indices varying in precision, including trophic levels, a coarse‐scale and a fine‐scale categorical index, and quantitative estimates of dietary carotenoids. This last method was used as the benchmark. For comparisons among taxa, all but the trophic level index were significantly correlated with each other. However, for comparisons of species within taxa, the fine‐scale index outperformed the coarse‐scale index, which in turn outperformed the trophic level index. In addition, each method has advantages and disadvantages, as well as underlying assumptions that must be considered. Examination and comparison of several possible methods of diet assessment appears to highlight these so that the best possible index is used given available data, and it is recommended that such a step be taken prior to the inclusion of estimated nutrient intake in any statistical analysis. Although applied to avian carotenoids here, this method could readily be applied to other taxa and types of nutrients.