bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of high spatial resolution x-ray radiography system equipped with multiwalled carbon nanotube field emission cathode
Authors: Yabushita Ryosuke , Hata Koichi
Published: April 2008

An x-ray radiography system (XRS) equipped with a multiwalled carbon nanotube cathode was developed. This system has ordinary scanning electron microscopy (SEM) functions available for the precise adjustment of focusing conditions including astigmatism and alignment of an electron beam. The electron beam diameter on a target, which is one factor that limits spatial resolution of XRS, was estimated as 50nm from the resolution of SEM images obtained. X-ray images were taken as a demonstration of the XRS, and clear images with resolution higher than 700nm were successfully obtained.
Fabrication of nanopores with subnanometer precision on poly(methyl methacrylate) nanofibers by in situ electron beam irradiation
Authors: Duan H. G. , Xie E. Q. , Han L.
Published: April 2008

Nanopores with subnanometer precision were fabricated and fine-tuned in freestanding poly(methyl methacrylate) (PMMA) nanofibers by in situ electron beam irradiation. The nanopores were formed and expanded by focused electron beam irradiation, which was attributed to the sputtering and decomposition of PMMA. Meanwhile, the fabricated nanopores could also be shrunk and closed by low electron intensity irradiation, which may have been caused by surface tension induced mass flow due to the glass transition of PMMA. This work provides a new method to fabricate precise nanopores. It also provides important evidence about the theory of direct nanofabrication by electron beam irradiation.
Field emission at nanometer distances for high-resolution positioning
Authors: le Fèbre A. J. , Abelmann L. , Lodder J. C.
Published: April 2008

The dependence of the field emission effect on distance is applied for displacement sensing and high-resolution positioning. Silicon atomic force microscopy probes were used as a field emission source by applying voltages up to 400 V between this probe and a counter-electrode sample consisting of TiW sputtered on a silicon wafer. From current-voltage characteristics measured for distances varying from 50 to 950 nm, values for the field enhancement factor were determined which show a dependence on the electrode separation. This dependence can be correctly described by a model the authors developed using finite-element calculations and is determined by the emitter geometry and tip radius. Feedback to the probe position was used to maintain a constant current to apply this distance dependence for positioning. When increasing the applied voltage from 5 to 40 V for a constant current of 3 nA, the probe position is raised ∼90 nm. The nonlinear sensitivity of this positioning method is determined by the varying field enhancement and can be fitted by the same calculated model. Using feedback, the field emitter can be positioned with high lateral resolution and scanned over a conducting surface. Increasing the bias voltage from 3 to 50 V results in an increase in the emitter-sample distance and a decrease in lateral resolution. Damage to the scanned surface has to be prevented by using a current-limiting resistor and by annealing the probe and sample under ultra high vacuum conditions before use.
Chaotic Dirac Billiard in Graphene Quantum Dots
Authors: Ponomarenko L. A. , Schedin F. , Katsnelson M. I. , Yang R. , Hill E. W. , Novoselov K. S. , Geim A. K.
Published: April 2008

The exceptional electronic properties of graphene, with its charge carriers mimicking relativistic quantum particles and its formidable potential in various applications, have ensured a rapid growth of interest in this new material. We report on electron transport in quantum dot devices carved entirely from graphene. At large sizes (>100 nanometers), they behave as conventional single-electron transistors, exhibiting periodic Coulomb blockade peaks. For quantum dots smaller than 100 nanometers, the peaks become strongly nonperiodic, indicating a major contribution of quantum confinement. Random peak spacing and its statistics are well described by the theory of chaotic neutrino billiards. Short constrictions of only a few nanometers in width remain conductive and reveal a confinement gap of up to 0.5 electron volt, demonstrating the possibility of molecular-scale electronics based on graphene.
Picosecond Coherent Optical Manipulation of a Single Electron Spin in a Quantum Dot
Authors: Berezovsky J. , Mikkelsen M. H. , Stoltz N. G. , Coldren L. A. , Awschalom D. D.
Published: April 2008

Most schemes for quantum information processing require fast single-qubit operations. For spin-based qubits, this involves performing arbitrary coherent rotations of the spin state on time scales much faster than the spin coherence time. By applying off-resonant, picosecond-scale optical pulses, we demonstrated the coherent rotation of a single electron spin through arbitrary angles up to π radians. We directly observed this spin manipulation using time-resolved Kerr rotation spectroscopy and found that the results are well described by a model that includes the electronnuclear spin interaction. Measurements of the spin rotation as a function of laser detuning and intensity confirmed that the optical Stark effect is the operative mechanism.
Qinghaosu (Artemisinin): The Price of Success
Authors: White N. J.
Published: April 2008

Artemisinin and its derivatives have become essential components of antimalarial treatment. These plant-derived peroxides are unique among antimalarial drugs in killing the young intraerythrocytic malaria parasites, thereby preventing their development to more pathological mature stages. This results in rapid clinical and parasitological responses to treatment and life-saving benefit in severe malaria. Artemisinin combination treatments (ACTs) are now first-line drugs for uncomplicated falciparum malaria, but access to ACTs is still limited in most malaria-endemic countries. Improved agricultural practices, selection of high-yielding hybrids, microbial production, and the development of synthetic peroxides will lower prices. A global subsidy would make these drugs more affordable and available. ACTs are central to current malaria elimination initiatives, but there are concerns that tolerance to artemisinins may be emerging in Cambodia.
Interlaboratory Comparison of Results of an Anthrax Lethal Toxin Neutralization Assay for Assessment of Functional Antibodies in Multiple Species
Authors: Omland Kristian S. , Brys April , Lansky David , Clement Kristin , Lynn Freyja
Published: April 2008

The anthrax lethal toxin neutralization assay (TNA) will likely be used to correlate the protection offered by new anthrax vaccines in animal models to the immunogenicity that will be provided in humans. TNA data are being generated in several different laboratories to measure the immune responses in rabbits, nonhuman primates, and humans. In order to compare data among species and laboratories, a collaborative study was conducted in which 108 samples from the three species were analyzed in seven independent laboratories. Six of the seven laboratories had participated in an interlaboratory technology transfer of the TNA. Analysis of the titration curves generated by samples from each species indicated that the behaviors of the samples from all species were similar; the upper and lower asymptotes and the slopes of the curves were less than 30% divergent from those for human reference material. Dilutional linearity was consistent among samples from each species, with spike to effective dilution at 50% inhibition (ED
50
) slopes of less than 1.2 for all species. Agreement among the laboratories with consensus values was within 10% of the ED
50
s for all samples and within 7.5% of the quotients of the test sample ED
50
and the reference standard ED
50
(NF
50
s) for all samples. The relative standard deviations obtained when data from all laboratories and for all species were combined were 45% for the ED
50
s and 35% for the NF
50
s. These precision data suggest that the NF
50
readout may normalize the values generated by different laboratories. This study demonstrates that the TNA is a panspecies assay that can be performed in several different laboratories with a high degree of quantitative agreement and precision.
Characterization of In Vitro-Generated and Clinical Optochin-Resistant Strains of
Streptococcus pneumoniae
Isolated from Argentina
Authors: Cortes Paulo R. , Orio Andrea G. Albarracín , Regueira Mabel , Piñas Germán E. , Echenique José
Published: April 2008

Optochin susceptibility is a key test used for pneumococcal diagnosis, but optochin-resistant (Opt
r
) pneumococci have been reported in the last 2 decades. In this work, we characterized eight Opt
r
clinical strains which presented a new mutation, G47V, a predominant A49S mutation (recently reported in Brazil) and A49T. These mutations were found in the
c
subunit of the F
0
F
1
ATPase encoded by the
atpC
gene, and W206C was found in the
a
subunit encoded by the
atpA
gene. The Opt
r
clinical isolates were analyzed by BOX PCR, multilocus sequence typing, and serotype and antimicrobial resistance profiles, and they showed no epidemiological relationship. To characterize the Opt
r
mutations that could emerge among clinical strains, we studied a pool of spontaneous Opt
r
colonies obtained in vitro from the virulent D39 strain. We compared the
atpAC
mutations of these Opt
r
pneumococci (with or without passage through C57BL/6 mice) with those described in the clinical isolates. This analysis revealed three new mutations, G47V and L26M in the
c
subunit and L184S in the
a
subunit. Most of the mutations identified in the laboratory-generated Opt
r
strains were also found in clinical strains, with the exception of the L26M and L184S mutations, and we suppose that both mutations could emerge among invasive strains in the future. Considering that
atpAC
are essential genes, we propose that all spontaneous mutations that confer in vitro optochin resistance would not present severe physiological alterations in
S. pneumoniae
and may be carried by circulating pneumococcal strains.
Coronavirus Nonstructural Protein 16 Is a Cap-0 Binding Enzyme Possessing (Nucleoside-2′
O
)-Methyltransferase Activity
Authors: Decroly Etienne , Imbert Isabelle , Coutard Bruno , Bouvet Mickaël , Selisko Barbara , Alvarez Karine , Gorbalenya Alexander E. , Snijder Eric J. , Canard Bruno
Published: April 2008

The coronavirus family of positive-strand RNA viruses includes important pathogens of livestock, companion animals, and humans, including the severe acute respiratory syndrome coronavirus that was responsible for a worldwide outbreak in 2003. The unusually complex coronavirus replicase/transcriptase is comprised of 15 or 16 virus-specific subunits that are autoproteolytically derived from two large polyproteins. In line with bioinformatics predictions, we now show that feline coronavirus (FCoV) nonstructural protein 16 (nsp16) possesses an
S
-adenosyl-
l
-methionine (AdoMet)-dependent RNA (nucleoside-2′
O
)-methyltransferase (2′
O
-MTase) activity that is capable of cap-1 formation. Purified recombinant FCoV nsp16 selectively binds to short capped RNAs. Remarkably, an N7-methyl guanosine cap (
7Me
GpppAC
3-6
) is a prerequisite for binding. High-performance liquid chromatography analysis demonstrated that nsp16 mediates methyl transfer from AdoMet to the 2′
O
position of the first transcribed nucleotide, thus converting
7Me
GpppAC
3-6
into
7Me
GpppA
2′

O

Me
C
3-6
. The characterization of 11 nsp16 mutants supported the previous identification of residues K45, D129, K169, and E202 as the putative K-D-K-E catalytic tetrad of the enzyme. Furthermore, residues Y29 and F173 of FCoV nsp16, which may be the functional counterparts of aromatic residues involved in substrate recognition by the vaccinia virus MTase VP39, were found to be essential for both substrate binding and 2′
O
-MTase activity. Finally, the weak inhibition profile of different AdoMet analogues indicates that nsp16 has evolved an atypical AdoMet binding site. Our results suggest that coronavirus mRNA carries a cap-1, onto which 2′
O
methylation follows an order of events in which 2′
O
-methyl transfer must be preceded by guanine N7 methylation, with the latter step being performed by a yet-unknown N7-specific MTase.
A Conserved Sequence within the H2 Subunit of the Vaccinia Virus Entry/Fusion Complex Is Important for Interaction with the A28 Subunit and Infectivity
Authors: Nelson Gretchen E. , Wagenaar Timothy R. , Moss Bernard
Published: April 2008

The recently described vaccinia virus entry/fusion complex (EFC) comprises at least eight polypeptides that are conserved in all poxviruses. Neither the structure of the complex nor the roles of individual subunits are known. Here we provide evidence for an interaction between the H2 and A28 subunits in the context of a virus infection as well as in uninfected cells transfected with plasmids expressing the corresponding genes. We focused on a highly conserved 21-amino acid-segment in H2 that is flanked by cysteine residues. The effect of amino acid substitutions within the 21-amino-acid segment was determined by an infectivity complementation assay using a conditional H2-null mutant of vaccinia virus. Mutations that had no, moderate, or large negative effects on complementation were found. The latter group included glutamic acid substitutions of leucine and individual glycines and alanine substitution of both glycines within a LGYSG sequence. Mutations with the most pronounced effect on infectivity disrupted the interaction of H2 with A28 to the greatest extent in both infected and uninfected cells. These data indicate that the LGYSG sequence is important for the interaction of H2 with A28 and suggest that this sequence is buried within the EFC complex.
Bovine Papillomavirus Type 1: from Clathrin to Caveolin
Authors: Laniosz Valerie , Holthusen Kirsten A. , Meneses Patricio I.
Published: April 2008

Viruses may infect cells through clathrin-dependent, caveolin-dependent, or clathrin- and caveolin-independent endocytosis. Bovine papillomavirus type 1 (BPV1) entry into cells has been shown to occur by clathrin-dependent endocytosis, a pathway that involves the formation of clathrin-coated pits and fusion to early endosomes. Recently, it has been demonstrated that the closely related JC virus can enter cells in clathrin-coated vesicles and subsequently traffic to caveolae, the organelle where vesicles of the caveolin-dependent pathway deliver their cargo. In this study, we use immunofluorescence staining of BPV1 pseudovirions to show that BPV1 overlaps with the endosome marker EEA1 early during infection and later colocalizes with caveolin-1. We provide evidence through the colocalization of BPV1 with transferrin and cholera toxin B that BPVl trafficking may not be restricted to the clathrin-dependent pathway. Disrupting the entry of caveolar vesicles did not affect BPV1 infection; however, we show that blocking the caveolar pathway postentry results in a loss of BPV1 infection. These data indicate that BPV1 may enter by clathrin-mediated endocytosis and then utilize the caveolar pathway for infection, a pattern of trafficking that may explain the slow kinetics of BPV1 infection.
Infection with Vpr-Positive Human Immunodeficiency Virus Type 1 Impairs NK Cell Function Indirectly through Cytokine Dysregulation of Infected Target Cells
Authors: Majumder Biswanath , Venkatachari Narasimhan J. , O'Leary Shaylee , Ayyavoo Velpandi
Published: April 2008

Human immunodeficiency virus type 1 (HIV-1) infection has been implicated in impairing various aspects of NK cell function in viremic condition, and several viral factors contribute to these defects. Here, we evaluated the effect of HIV-1 Vpr on NK cell cytolytic function and cytokine (gamma interferon [IFN-γ]) production in the context of infection and exposure. Our data indicate that NK cells derived from a peripheral blood mononuclear cell culture infected in vitro with HIV-1 vpr(+) virus or exposed to recombinant Vpr protein exhibited reduced target cell killing in conjunction with diminished expression of CD107a and reduced IFN-γ production compared to their Vpr-negative counterparts. This Vpr-induced NK cell defect is in part through differential regulation of interleukin-12 and transforming growth factor β production by the infected target cells and concomitant activation of Smad3 signaling pathway. Collectively, these results illustrate the ability of Vpr to impair NK cell-mediated innate immune functions indirectly by dysregulating multiple cytokines in the infected target cells, thus increasing disease severity and affecting the final outcome in HIV-1 infection.
Cell-Type-Specific Tyrosine Phosphorylation of the Herpes Simplex Virus Tegument Protein VP11/12 Encoded by Gene UL46
Authors: Zahariadis George , Wagner Melany J. , Doepker Rosalyn C. , Maciejko Jessica M. , Crider Carly M. , Jerome Keith R. , Smiley James R.
Published: April 2008

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells play key roles in limiting herpesvirus infections; consequently, many herpesviruses, including herpes simplex virus (HSV), have evolved diverse strategies to evade and/or disarm these killer lymphocytes. Previous studies have shown that CTL and NK cells are functionally inactivated following contact with HSV-infected fibroblasts. During studies of the mechanisms involved, we discovered that HSV-inactivated NK-92 NK cells and Jurkat T cells contain a strikingly prominent, novel, ca. 90-kDa tyrosine-phosphorylated protein that we identified as the HSV tegument protein VP11/12. Inasmuch as VP11/12 produced in fibroblasts and epithelial cells is not obviously tyrosine phosphorylated, these data suggested that VP11/12 serves as the substrate of a cell-type-specific protein tyrosine kinase. Consistent with this hypothesis, VP11/12 was also tyrosine phosphorylated in B lymphocytes, and this modification was severely reduced in Jurkat T cells lacking the lymphocyte-specific Src family kinase Lck. These findings demonstrate that HSV tegument proteins can be differentially modified depending on the cell type infected. Our data also raise the possibility that VP11/12 may modulate one or more lymphocyte-specific signaling pathways or serve another lymphocyte-specific function. However, HSV type 1 mutants lacking the UL46 gene retained the ability to block signaling through the T-cell receptor in Jurkat cells and remained competent to functionally inactivate the NK-92 NK cell line, indicating that VP11/12 is not essential for lymphocyte inactivation. Further studies are therefore required to determine the biological function of tyrosine-phosphorylated VP11/12.
Length Requirements for Membrane Fusion of Influenza Virus Hemagglutinin Peptide Linkers to Transmembrane or Fusion Peptide Domains
Authors: Li Zhu-Nan , Lee Byeong-Jae , Langley William A. , Bradley Konrad C. , Russell Rupert J. , Steinhauer David A.
Published: April 2008

During membrane fusion, the influenza A virus hemagglutinin (HA) adopts an extended helical structure that contains the viral transmembrane and fusion peptide domains at the same end of the molecule. The peptide segments that link the end of this rod-like structure to the membrane-associating domains are approximately 10 amino acids in each case, and their structure at the pH of fusion is currently unknown. Here, we examine mutant HAs and influenza viruses containing such HAs to determine whether these peptide linkers are subject to specific length requirements for the proper folding of native HA and for membrane fusion function. Using pairwise deletions and insertions, we show that the region flanking the fusion peptide appears to be important for the folding of the native HA structure but that mutant proteins with small insertions can be expressed on the cell surface and are functional for membrane fusion. HA mutants with deletions of up to 10 residues and insertions of as many as 12 amino acids were generated for the peptide linker to the viral transmembrane domain, and all folded properly and were expressed on the cell surface. For these mutants, it was possible to designate length restrictions for efficient membrane fusion, as functional activity was observed only for mutants containing linkers with insertions or deletions of eight residues or less. The linker peptide mutants are discussed with respect to requirements for the folding of native HAs and length restrictions for membrane fusion activity.
Sindbis Virus Conformational Changes Induced by a Neutralizing Anti-E1 Monoclonal Antibody
Authors: Hernandez Raquel , Paredes Angel , Brown Dennis T.
Published: April 2008

A rare Sindbis virus anti-E1 neutralizing monoclonal antibody, Sin-33, was investigated to determine the mechanism of in vitro neutralization. A cryoelectron microscopic reconstruction of Sindbis virus (SVHR) neutralized with FAb from Sin-33 (FAb-33) revealed conformational changes on the surface of the virion at a resolution of 24 Å. FAb-33 was found to bind E1 in less than 1:1 molar ratios, as shown by the absence of FAb density in the reconstruction and stoichiometric measurements using radiolabeled FAb-33, which determined that about 60 molecules of FAb-33 bound to the 240 possible sites in a single virus particle. FAb-33-neutralized virus particles became sensitive to digestion by endoproteinase Glu-C, providing further evidence of antibody-induced structural changes within the virus particle. The treatment of FAb-33-neutralized or Sin-33-neutralized SVHR with low pH did not induce the conformational rearrangements required for virus membrane-cell membrane fusion. Exposure to low pH, however, increased the amount of Sin-33 or FAb-33 that bound to the virus particles, indicating the exposure of additional epitopes. The neutralization of SVHR infection by FAb-33 or Sin-33 did not prevent the association of virus with host cells. These data are in agreement with the results of previous studies that demonstrated that specific antibodies can inactivate the infectious state of a metastable virus in vitro by the induction of conformational changes to produce an inactive structure. A model is proposed which postulates that the induction of conformational changes in the infectious state of a metastable enveloped virus may be a general mechanism of antibody inactivation of virus infectivity.
Vaccinia Virus DNA Ligase Recruits Cellular Topoisomerase II to Sites of Viral Replication and Assembly
Authors: Lin Y.-C. James , Li Jianhong , Irwin Chad R. , Jenkins Heather , DeLange Luke , Evans David H.
Published: April 2008

Vaccinia virus replication is inhibited by etoposide and mitoxantrone even though poxviruses do not encode the type II topoisomerases that are the specific targets of these drugs. Furthermore, one can isolate drug-resistant virus carrying mutations in the viral DNA ligase and yet the ligase is not known to exhibit sensitivity to these drugs. A yeast two-hybrid screen was used to search for proteins binding to vaccinia ligase, and one of the nine proteins identified comprised a portion (residue 901 to end) of human topoisomerase IIβ. One can prevent the interaction by introducing a C
11
-to-Y substitution mutation into the N terminus of the ligase bait protein, which is one of the mutations conferring etoposide and mitoxantrone resistance. Coimmunoprecipitation methods showed that the native ligase and a Flag-tagged recombinant protein form complexes with human topoisomerase IIα/β in infected cells and that this interaction can also be disrupted by mutations in the A50R (ligase) gene. Immunofluorescence microscopy showed that both topoisomerase IIα and IIβ antigens are recruited to cytoplasmic sites of virus replication and that less topoisomerase was recruited to these sites in cells infected with mutant virus than in cells infected with wild-type virus. Immunoelectron microscopy confirmed the presence of topoisomerases IIα/β in virosomes, but the enzyme could not be detected in mature virus particles. We propose that the genetics of etoposide and mitoxantrone resistance can be explained by vaccinia ligase binding to cellular topoisomerase II and recruiting this nuclear enzyme to sites of virus biogenesis. Although other nuclear DNA binding proteins have been detected in virosomes, this appears to be the first demonstration of an enzyme being selectively recruited to sites of poxvirus DNA synthesis and assembly.
Authentic Replication and Recombination of
Tomato Bushy Stunt Virus
RNA in a Cell-Free Extract from Yeast
Authors: Pogany Judit , Nagy Peter D.
Published: April 2008

To study the replication of
Tomato bushy stunt virus
(TBSV), a small tombusvirus of plants, we have developed a cell-free system based on a
Saccharomyces cerevisiae
extract. The cell-free system was capable of performing a complete replication cycle on added plus-stranded TBSV replicon RNA (repRNA) that led to the production of ∼30-fold-more plus-stranded progeny RNAs than the minus-stranded replication intermediate. The cell-free system also replicated the full-length TBSV genomic RNA, which resulted in production of subgenomic RNAs as well. The cell-free system showed high template specificity, since a mutated repRNA, minus-stranded repRNA, or a heterologous viral RNA could not be used as templates by the tombusvirus replicase. Similar to the in vivo situation, replication of the TBSV replicon RNA took place in a membraneous fraction, in which the viral replicase-RNA complex was RNase and protease resistant but sensitive to detergents. In addition to faithfully replicating the TBSV replicon RNA, the cell-free system was also capable of generating TBSV RNA recombinants with high efficiency. Altogether, tombusvirus replicase in the cell-free system showed features remarkably similar to those of the in vivo replicase, including carrying out a complete cycle of replication, high template specificity, and the ability to recombine efficiently.
Psychosocial predictors of failure to return to work in non-chronic non-specific low back pain: a systematic review
Authors: Iles R A , Davidson M , Taylor N F
Published: April 2008

Objectives:

To identify psychosocial predictors of failure to return to work in non-chronic (lasting less than 3 months) non-specific low back pain (NSLBP).

Methods:

A systematic review of prognostic studies was carried out. Medline, Embase, PsychINFO, CINAHL and PEDro electronic bibliographic databases up to April 2006 were searched. Included studies took baseline measures in the non-chronic phase of NSLBP (ie, within 3 months of onset), included at least one psychosocial variable and studied a sample in which at least 75% of participants had NSLBP. Baseline measures had to be used to predict at least one work-specific outcome.

Results:

The search identified 24 studies meeting the inclusion criteria. From these studies there is strong evidence that recovery expectation is predictive of work outcome and that depression, job satisfaction and stress/psychological strain are not predictive of work outcome. There is moderate evidence that fear avoidance beliefs are predictive of work outcome and that anxiety is not predictive of work outcome. There is insufficient evidence to determine whether compensation or locus of control are predictive of work outcome.

Conclusions:

To predict work outcome in non-chronic NSLBP, psychosocial assessment should focus on recovery expectation and fear avoidance. More research is needed to determine the best method of measuring these constructs and to determine how to intervene when a worker has low recovery expectations.
Lung and other cancer site mortality in a cohort of Italian cotton mill workers
Authors: Mastrangelo G , Fadda E , Rylander R , Milan G , Fedeli U , Rossi di Schio M , Lange J H
Published: April 2008

Background:

Several studies report a lower than expected mortality in lung cancer among workers exposed to organic dust. Recent studies also reported a decreased risk for cancer at other sites.

Objectives:

To evaluate the mortality from lung and other cancer sites in cotton mill workers.

Material and methods:

A cohort of 3961 Italian cotton mill workers was divided into those working with carding (exposed to high levels of endotoxin-containing cotton dust) and other tasks, which generally have lower exposure. Standardised mortality ratios (SMRs), with 95% confidence intervals (CI), were calculated using death rates of the regional general population as a reference. Cancer mortality was analysed in relation to the length of employment in the two task groups. An internal analysis was also performed through Poisson regression.

Results:

Among workers in carding departments, lung cancer SMRs were 1.88 (CI: 0.69 to 4.08), 1.01 (CI: 0.20 to 2.94) and 0.22 (CI: 0.00 to 1.24), respectively, for <6, 6–12 and >12 years of employment (χ2for trend = 5.45; p<0.05). A significant (p = 0.04) trend was confirmed by Poisson regression. No reduced risks were found for other forms of cancer, nor for those working with other tasks.

Conclusions:

The results support previous reports that a high and prolonged exposure to cotton dust and other endotoxin-containing organic dusts is related to a lower risk of lung cancer. There was no indication of a reduced risk for other forms of cancer.
Lung cancer and exposure to arsenic in rural Bangladesh
Authors: Mostafa M G , McDonald J C , Cherry N M
Published: April 2008

Background:

Arsenic is a known carcinogen but the risk of lung cancer from the widespread contamination of drinking water in rural Bangladesh has not been estimated.

Objectives:

To determine whether estimated exposure of villagers in Bangladesh to arsenic in drinking water differed between those with lung cancer and those with non-malignant lesions.

Methods:

Data were obtained from 7286 subjects who underwent lung biopsy in 2003–2006 at a diagnostic centre taking referrals from throughout Bangladesh. Analysis was limited to 5372 people living in villages for the last 10 years who reported using tube well water. Of these, 3223 with a primary lung tumour were enrolled as cases and 1588 with non-malignant lesions as referents in an unmatched analysis. Arsenic exposure was estimated by average concentrations for each of 64 districts. Logistic regression was used to test the effects of age, arsenic and smoking on risk and to investigate relationship to cell type.

Results:

Male cases were older than referents and more likely to smoke, to smoke >20 units/day and to smoke bidi—small, hand-rolled cigarettes. Odds ratios for lung cancer increased steadily with mean arsenic concentration, but the confidence interval excluded 1.0 only at concentrations >100 μg/l (OR 1.45, 95% CI 1.16 to 1.80). This trend was seen only in smokers where the increased risk at >100 μg/l was 1.65 (95% CI 1.25 to 2.18). A similar trend was seen in women smokers. Squamous cell lung cancer was more frequent in smokers and, having adjusted for smoking, in districts with arsenic concentrations >100 μg/l.

Conclusions:

Among Bangladeshis who smoke, those whose drinking water is contaminated with arsenic at concentrations >100 μg/l are at increased risk of lung cancer. With high levels of exposure misclassification and short latency of exposure, the study cannot estimate or exclude the likely long term risk in non-smokers and at lower arsenic concentrations.
PHYSIOLOGICAL AND BIOCHEMICAL STUDIES IN PLANT METABOLISM: VIII. THE DISTRIBUTION OF INVERTASE IN THE FIRST LEAF OF KHAPLI WHEAT
Authors: Roberts D. W. A.
Published: April 2008

The kinetics of wheat leaf invertase have been investigated as a basis for its quantitative estimation. No evidence was obtained which indicated that wheat leaf invertase consists of a phosphorylase and a phosphatase. Solid preparations of the enzyme may be made by precipitating the invertase with ammonium sulphate from wheat leaf juice which has been previously freed from chlorophyll by precipitation with acetate buffer at pH 4.5. A study of the distribution of this enzyme in the first leaf of wheat shows that the enzyme reaches its maximum concentration in the leaf just at the close of the period of elongation. The enzyme is more abundant in the basal part of the leaf than the tip and this condition is taken to indicate that the enzyme is associated with the vascular tissue (phloem or phloem parenchyma) rather than the chlorenchyma.
STUDIES ON THE PHYSIOLOGY OF ELSINOE VENETA
Authors: Kemp W. G.
Published: April 2008

A study was made of the effect of certain nutritional and environmental factors on the growth and pigmentation of the mycelium, the sporulation, and the germination of the conidia of a "convoluted" isolate of Elsinoe veneta (Burkh.) Jenkins, the fungus responsible for the anthracnose disease of raspberries. This isolate utilized with varying degrees of efficiency various mono-, oligo-, and polysaccharides as well as certain organic alcohols as its sole source of carbon for growth. Either a nitrate, ammonium, amino, or imidazole nitrogen compound supported the fungus in culture. Maximum growth of the mycelium occurred in the presence of soluble starch and asparagine, whereas optimum sporulation of the conidia was obtained on media containing potato starch and sodium nitrate. In general, the production of conidia was markedly reduced on media favorable for excessive vegetative growth. Both a decrease in the volume of the medium and in the concentration of either a specific nutrient or of total nutrients adversely influenced the production of mycelium. Temperatures above 30 °C. and below 21 °C. decreased the percentage germination of conidia and restricted the growth of the fungus. Growth and sporulation occurred over a wide range of pH values. The optimum initial pH for both growth and sporulation was 4.0. E. veneta produced conidia and grew as well in continuous darkness as in alternate diffuse light and darkness. Young potted raspberry plants growing in the greenhouse, when inoculated with conidia produced in culture, developed typical anthracnose lesions on the canes.
ANTAGONISM BY SPECIES OF ALTERNARIA AND THE ISOLATION OF A CRYSTALLINE SUBSTANCE FROM THE FILTRATE OF CULTURES OF A. RADICINA
Authors: Newton Wm.
Published: April 2008

Culture filtrates of five species of Alternaria were antagonistic to Phytophthora erythroseptica. Those of A. radicina exerted the greatest effect and they were followed in order of effectiveness by A. dianthicola, A. solani, A. brassicicola, and A. tenuis. The antagonistic principle in the filtrate of A. radicina was readily removed by activated carbon. By extracting this carbon with acetone, substantial yields were obtained of colorless, needlelike crystals, quite insoluble in water, but readily soluble in acetone, ethyl alcohol, ether, benzene, concentrated sulphuric acid, and 10% sodium hydroxide. The m.p. of the crystals, 204 °C. to 208 °C, and the deep pink color in solutions of sodium hydroxide distinguish the substance from alternaric acid. Water suspensions of the crystals were much less antagonistic to P. erythroseptica than the original filtrate and had little or no effect upon several species of bacteria.
STUDIES ON INDOLEACETIC ACID METABOLISM: I. THE EFFECT OF METHYL UMBELLIFERONE, MALEIC HYDRAZIDE, AND 2,4-D ON INDOLEACETIC ACID OXIDATION
Authors: Andreae W. A. , Andreae Shirley R.
Published: April 2008

Evidence is presented that IAA is oxidized with the liberation of hydrogen peroxide, and that the rate of oxidation is limited by a light-activated step. Methyl umbelliferone, maleic hydrazide, and 2,4-D stimulate IAA oxidation, presumably by accelerating the light-activated step. The stimulatory action of all three substances is overcome to a greater or less extent by scopoletin, which competitively inhibits the oxidation of IAA. It is suggested that maleic hydrazide and methyl umbelliferone may inhibit growth by causing an excessive oxidation of IAA. The importance of fluorescent coumarin derivatives on the photooxidation of IAA in vivo is discussed.
GROWTH AND MORPHOGENESIS IN THE CANADIAN FOREST SPECIES: I. THE CONTROLS OF CAMBIAL AND APICAL ACTIVITY IN PINUS RESINOSA AIT.
Authors: Duff G. H. , Nolan Norah J.
Published: April 2008

The anomalous complexity of the annual rings of young trees which generally disqualifies them from use in growth studies is, in P. resinosa, found to arise from a remarkably thorough organization of ring width and therefore of cambial activity in the tree under the influence of intrinsic determinants. The pattern is manifest when the widths of the internodal wood rings of a single year are followed in sequence from internode to internode down the tree from the apex. A similarly patterned view of the rings is obtained when the ring widths are traced in the ring sequence, conventional for growth studies, that passes from ring to ring in a given internode. The controlling intrinsic factors are held to be nutritional gradients in the axis inferred from the distribution of foliage and light along the axis of trees growing in the forest and in the open.In both types of sequence the pattern obscures the variations induced by random extrinsic factors and severely limits the value of these sequences for examining the effect of such factors. This disability can be avoided by the use of a third sequence of ring widths in which each term is the width of a ring which was laid down in an internode different but of the same age at the time of ring formation as the others in the sequence. Such sequences have never been used in growth studies. Yet they are found to be unpatterned and the effect of the fluctuating extrinsic factors can be examined effectively in them and in them alone.The complex relation between the responses of the cambium thus determined and those of the apical growing point to the random extrinsic factors is found to derive from the discontinuity of terminal growth introduced by the winter pause between bud formation and axial extension. These two stages of terminal growth are influenced by the extrinsic factors of the two different years. The effect on the cambium is simpler than this but is determinably related to that on the apical growing point.The results afford the ground for a first advance toward the removal of the disqualification of the use of young trees in studies of growth and of its factorial control.
Influence of seasonal changes in runoff and extreme events on dissolved organic carbon trends in wetland- and upland-draining streams
Authors: Eimers M Catherine , Buttle Jim , Watmough Shaun A
Published: April 2008

Dissolved organic carbon (DOC) fluxes at eight headwater basins in south-central Ontario were strongly related to seasonal streamflow, and extreme events contributed to both interannual and intercatchment variability. Six catchments with high stream DOC and greater peatland coverage exhibited a different seasonal pattern of DOC concentration compared with two catchments with low DOC and less wetland influence. In wetland-dominated catchments, DOC concentrations decreased during fall wet-up and spring melt, and because of the dominance of the spring melt period in annual budgets, variations in spring flow explained 39%–48% of the intervariability in DOC concentration. Significant increases in average DOC concentration between 1980 and 2001 at all six wetland-dominated catchments were driven by relatively high DOC concentrations in the latter years of record, consistent with low spring flow in these years, and were not translated into greater DOC export to downstream lakes. Localized rainstorms in summer and fall resulted in differences in DOC export among adjacent catchments, and a single fall storm in September 1998 was only detected at one of six catchments draining into Harp Lake but accounted for one-quarter of the annual tributary DOC load to the lake.
Combining multiple Bayesian data analyses in a sequential framework for quantitative fisheries stock assessment
Authors: Michielsens Catherine G.J. , McAllister Murdoch K , Kuikka Sakari , Mäntyniemi Samu , Romakkaniemi Atso , Pakarinen Tapani , Karlsson Lars , Uusitalo Laura
Published: April 2008

This paper presents a sequential Bayesian framework for quantitative fisheries stock assessment that relies on a wide range of fisheries-dependent and -independent data and information. The presented methodology combines information from multiple Bayesian data analyses through the incorporation of the joint posterior probability density functions (pdfs) in subsequent analyses, either as informative prior pdfs or as additional likelihood contributions. Different practical strategies are presented for minimising any loss of information between analyses. Using this methodology, the final stock assessment model used for the provision of the management advice can be kept relatively simple, despite the dependence on a large variety of data and other information. This methodology is illustrated for the assessment of the mixed-stock fishery for four wild Atlantic salmon (Salmo salar) stocks in the northern Baltic Sea. The incorporation of different data and information results in a considerable update of previously available smolt abundance and smolt production capacity estimates by substantially reducing the associated uncertainty. The methodology also allows, for the first time, the estimation of stock–recruit functions for the different salmon stocks.
Spatial analysis shows that fishing enhances the climatic sensitivity of marine fishes
Authors: Hsieh Chih-hao , Reiss Christian S , Hewitt Roger P , Sugihara George
Published: April 2008

We compare the changes in geographic distribution of exploited fish species versus unexploited ones living in the same environment. For this comparative study, we use the 50-year larval fish time series from the California Cooperative Oceanic Fisheries Investigations, which allows us to view fishing as a treatment effect in a long-term ecological experiment. Our results indicate that exploited species show a clearer distributional shift in response to environmental change than unexploited species, even after accounting for life history and ecological traits and phylogeny. The enhanced response (improved signal–noise ratio) to environmental change in exploited species may be a consequence of reduced spatial heterogeneity caused by fishery-induced age (size) truncation and the constriction of geographic distribution that accompanies fishing pressure. We suggest that reduced spatial heterogeneity can cause exploited populations to be more vulnerable to climate variability, an effect that could have considerable importance in the management of fish stocks. This is the first study to compare the geographic distributions of a large suite of exploited and unexploited fish species from the northeastern Pacific in response to climate variability.
Long-term assessments of ecological effects of anthropogenic stressors on aquatic ecosystems from paleoecological analyses: challenges to perspectives of lake management
Authors: Quinlan Roberto , Hall Roland I , Paterson Andrew M , Cumming Brian F , Smol John P
Published: April 2008

Paleolimnological techniques are important for determining background ecological conditions and ecosystem responses to stressors when long-term data sets are absent. Research at the Dorset Environmental Sciences Centre (Ontario, Canada) has included paleolimnological studies to determine the effects of anthropogenic stressors on shield lakes, including eutrophication, acidic deposition, and climate change. Diatom-based total phosphorus (TP) inferences suggest that [TP] has declined in some lakes, despite increased inputs from anthropogenic sources. When coupled with siliceous algae-based pH inferences that suggest landscape-scale long-term acidification, these results indicate that the ecological effects of anthropogenic P inputs are being masked by the cumulative effects of multiple stressors. Detailed stratigraphic analyses of lakes that have experienced severe anthropogenic disturbances indicate that despite measured and inferred recovery in epilimnetic [TP] to predisturbance concentrations, pelagic communities have not recovered to predisturbance community composition; profundal communities and the variables associated with water quality (e.g., hypolimnetic oxygen) have also not recorded recovery. This suggests that (i) typical modeling approaches to quantify the effects of anthropogenic inputs on lake water [TP] should be used with caution and (ii) lake management approaches that follow the paradigm of “water quality recovery = biological recovery” may not be applicable to ecosystems being affected by multiple anthropogenic stressors.
Changes in littoral benthic macroinvertebrate communities in relation to water chemistry in 17 Precambrian Shield lakes
Authors: Lento Jennifer , Dillon Peter J , Somers Keith M , Reid Ron A
Published: April 2008

Few studies of biological recovery from acidification have dealt with community responses to changes in water chemistry, despite the importance of environmental tolerance and biological interactions that may only be visible by examining the community as a whole. In this study, we examined the ability of pH and several water chemistry covariables to explain temporal changes in the littoral benthic macroinvertebrate communities of lakes recovering from acidification. Data from 17 lakes sampled from 1988 to 2002 were summarized using correspondence analysis and compared using Procrustes analysis. Canonical correspondence analysis was used to examine the relationship between chemical variables and community structure. Benthic community composition changed over the sampling period, with significant year-to-year changes from 1993 to 1998. Community composition and water chemistry were highly correlated throughout the study period, although the strongest correlations were found from 1993 to 1997, coinciding with the period of greatest change in the benthic community. These results suggest that benthic macroinvertebrate communities in these lakes have changed in response to changes in water chemistry that are consistent with recovery from acidification.
Long-term trends in catchment export and lake concentrations of base cations in the Dorset study area, central Ontario
Authors: Molot L A , Dillon Peter J
Published: April 2008

Decreases in exchangeable base cation reservoirs, base cation export, and lake concentrations have been reported for acid-sensitive regions in Europe and eastern North America. These decreases have produced smaller than anticipated increases in alkalinity in surface waters in response to reductions in sulphate emissions and may have ecological consequences. This study presents annual export rates of Ca, Mg, K, and Na from 20 forested catchments between 1978 and 1998 and concentrations in seven downstream lakes between 1975 and 2005 in an acid-sensitive region of central Ontario, Canada. In contrast to monovalent cation export, decreases in divalent cation export continued after an extended dry period ended. Lake concentration trends showed three distinct periods. The first period (1975–1976 to 1982–1983) coincided with high runoff and was characterized by relatively high Ca, Mg, and K concentrations. This was followed by a 10-year period of fluctuations around the long-term mean. Concentrations then dropped below the long-term means and remained 5%–20% below the means until 2004–2005. The latter trend in lake concentrations suggests that export likely remained low but stable after May 1998 (the last month for which export data are available). Na increased between 250% and 350% in Dickie and Harp lakes as a result of road salt contamination.