bluuebunny/crossref_metadata_2025 huggingface dataset:
The Diversity of Coliphages and Coliforms in Horse Feces Reveals a Complex Pattern of Ecological Interactions
Authors: Golomidova Alla , Kulikov Eugene , Isaeva Alina , Manykin Anatoly , Letarov Andrey
Published: August 2007

The diversity of coliphages and indigenous coliform strains (ICSs) simultaneously present in horse feces was investigated by culture-based and molecular methods. The richness of coliforms (as estimated by the Chao1 method) is about 1,000 individual ICSs distinguishable by genomic fingerprinting present in a single sample of feces. This unexpectedly high value indicates that some factor limits the competition of coliform bacteria in the horse gut microbial system. In contrast, the diversity of phages active against any selected ICS is generally limited to one to three viral genotypes present in the sample. The sensitivities of different ICSs to simultaneously present coliphages overlap only slightly; the phages isolated from the same sample on different ICSs are usually unrelated. As a result, the titers of phages in fecal extract as determined for different
Escherichia coli
strains and ICSs may differ by several orders of magnitude. Summarizing all the data, we propose that coliphage infection may provide a selection pressure that maintains the high level of coliform diversity, restricting the possibility of a few best competitors outgrowing other ICSs. We also observed high-magnitude temporal variations of coliphage titers as determined using an
E. coli
C600 test culture in the same animal during a 16-day period of monitoring. No correlation with total coliform count was observed. These results are in good agreement with our hypothesis.
Effect of Biotic and Abiotic Factors on In Vitro Proliferation, Encystment, and Excystment of
Pfiesteria piscicida
Authors: Saito Keiko , Drgon Tomás , Krupatkina Danara N. , Drgonova Jana , Terlizzi Daniel E. , Mercer Natalia , Vasta Gerardo R.
Published: August 2007

Pfiesteria
spp. are mixotrophic armored dinoflagellates populating the Atlantic coastal waters of the United States. They have been a focus of intense research due to their reported association with several fish mortality events. We have now used a clonal culture of
Pfiesteria piscicida
and several new environmental isolates to describe growth characteristics, feeding, and factors contributing to the encystment and germination of the organism in both laboratory and environmental samples. We also discuss applied methods of detection of the different morphological forms of
Pfiesteria
in environmental samples. In summary,
Pfiesteria
, when grown with its algal prey,
Rhodomonas
sp., presents a typical growth curve with lag, exponential, and stationary phases, followed by encystment. The doubling time in exponential phase is about 12 h. The profiles of proliferation under a standard light cycle and in the dark were similar, although the peak cell densities were markedly lower when cells were grown in the dark. The addition of urea, chicken manure, and soil extracts did not enhance
Pfiesteria
proliferation, but crude unfiltered spent aquarium water did. Under conditions of food deprivation or cold (4°C),
Pfiesteria
readily formed harvestable cysts that were further analyzed by PCR and scanning electron microscopy. The germination of
Pfiesteria
cysts in environmental sediment was enhanced by the presence of live fish: dinospores could be detected 13 to 15 days earlier and reached 5- to 10-times-higher peak cell densities with live fish than with artificial seawater or f/2 medium alone. The addition of ammonia, urea, nitrate, phosphate, or surprisingly, spent fish aquarium water had no effect.
Combined Imaging of Bacteria and Oxygen in Biofilms
Authors: Kühl Michael , Rickelt Lars F. , Thar Roland
Published: August 2007

Transparent sensors for microscopic O
2
imaging were developed by spin coating an ultrathin (<1- to 2-μm) layer of a luminescent O
2
indicator onto coverslips. The sensors showed (i) an ideal Stern-Volmer quenching behavior of the luminescence lifetime towards O
2
levels, (ii) homogeneous measuring characteristics over the sensor surface, and (iii) a linear decline of luminescence lifetime with increasing temperature. When a batch of such coverslip sensors has been characterized, their use is thus essentially calibration free at a known temperature. The sensors are easy to use in flow chambers and other growth devices used in microbiology. We present the first application for combined imaging of O
2
and bacteria in a biofilm flow chamber mounted on a microscope equipped with a spinning-disk confocal unit and a luminescence lifetime camera system.
Comparative Transcriptome Analysis of
Listeria monocytogenes
Strains of the Two Major Lineages Reveals Differences in Virulence, Cell Wall, and Stress Response
Authors: Severino Patricia , Dussurget Olivier , Vêncio Ricardo Z. N. , Dumas Emilie , Garrido Patricia , Padilla Gabriel , Piveteau Pascal , Lemaître Jean-Paul , Kunst Frank , Glaser Philippe , Buchrieser Carmen
Published: August 2007

Listeria monocytogenes
is a food-borne, opportunistic, bacterial pathogen causing a wide spectrum of diseases, including meningitis, septicemia, abortion, and gastroenteritis, in humans and animals. Among the 13
L. monocytogenes
serovars described, human listeriosis is mostly associated with strains of serovars 4b, 1/2b, and 1/2a. Within the species
L. monocytogenes
, three phylogenetic lineages are described. Serovar 1/2a belongs to phylogenetic lineage I, while serovars 4b and 1/2b group in phylogenetic lineage II. To explore the role of gene expression in the adaptation of
L. monocytogenes
strains of these two major lineages to different environments, as well as in virulence, we performed whole-genome expression profiling of six
L. monocytogenes
isolates of serovars 4b, 1/2b, and 1/2a of distinct origins, using a newly constructed
Listeria
multigenome DNA array. Comparison of the global gene expression profiles revealed differences among strains. The expression profiles of two strains having distinct 50% lethal doses, as assessed in the mouse model, were further analyzed. Gene ontology term enrichment analysis of the differentially expressed genes identified differences in protein-, nucleic acid-, carbon metabolism-, and virulence-related gene expression. Comparison of the expression profiles of the core genomes of all strains revealed differences between the two lineages with respect to cell wall synthesis, the stress-related sigma B regulon and virulence-related genes. These findings suggest different patterns of interaction with host cells and the environment, key factors for host colonization and survival in the environment.
Changes in Nucleoid Morphology and Origin Localization upon Inhibition or Alteration of the Actin Homolog, MreB, ofVibrio cholerae
Authors: Srivastava Preeti , Demarre Gäelle , Karpova Tatiana S. , McNally James , Chattoraj Dhruba K.
Published: August 2007

MreB is an actin homolog required for the morphogenesis of most rod-shaped bacteria and for other functions, including chromosome segregation. InCaulobacter crescentusandEscherichia coli, the protein seems to play a role in the segregation of sister origins, but its role inBacillus subtilischromosome segregation is less clear. To help clarify its role in segregation, we have here studied the protein inVibrio cholerae, whose chromosome I segregates like the one inC. crescentusand whose chromosome II like the one inE. coliorB. subtilis. The properties ofVibrioMreB were similar to those of its homologs in other bacteria in that it formed dynamic helical filaments, was essential for viability, and was inhibited by the drug A22. Wild-type (WT) cells exposed to A22 became spherical and larger. The nucleoids enlarged correspondingly, and the origin positions for both the chromosomes no longer followed any fixed pattern. However, the sister origins separated, unlike the situation in other bacteria. In mutants isolated as A22 resistant, the nucleoids in some cases appeared compacted even when the cell shape was nearly normal. In these cells, the origins of chromosome I were at the distal edges of the nucleoid but not all the way to the poles where they normally reside. The sister origins of chromosome II also separated less. Thus, it appears that the inhibition or alteration ofVibrioMreB can affect both the nucleoid morphology and origin localization.
The NtcA-Regulated
amtB
Gene Is Necessary for Full Methylammonium Uptake Activity in the Cyanobacterium
Synechococcus elongatus
Authors: Paz-Yepes Javier , Herrero Antonia , Flores Enrique
Published: August 2007

The Amt proteins constitute a ubiquitous family of transmembrane ammonia channels that permit the net uptake of ammonium by cells. In many organisms, there is more than one
amt
gene, and these genes are subjected to nitrogen control. The mature Amt protein is a homo- or heterooligomer of three Amt subunits. We previously characterized an
amt1
gene in the unicellular cyanobacterium
Synechococcus elongatus
strain PCC 7942. In this work, we describe the presence in this organism of a second
amt
gene,
amtB
, which encodes a protein more similar to the bacterial AmtB proteins than to any other characterized cyanobacterial Amt protein. The expression of
amtB
took place in response to nitrogen step-down, required the NtcA transcription factor, and occurred parallel to the expression of
amt1
. However, the transcript levels of
amtB
measured after 2 h of nitrogen deprivation were about 100-fold lower than those of
amt1
. An
S. elongatus amtB
insertional mutant exhibited an activity for uptake of [
14
C]methylammonium that was about 55% of that observed in the wild type, but inactivation of
amtB
had no noticeable effect on the uptake of ammonium when it was supplied at a concentration of 100 μM or more. Because an
S. elongatus amt1
mutant is essentially devoid of [
14
C]methylammonium uptake activity, the mature Amt transporter is functional in the absence of AmtB subunits but not in the absence of Amt1 subunits. However, the
S. elongatus amtB
mutant could not concentrate [
14
C]methylammonium within the cells to the same extent as the wild type. Therefore, AmtB is necessary for full methylammonium uptake activity in
S. elongatus
.
Diversity of Bacteriocins and Activity Spectrum inStreptococcus pneumoniae
Authors: Lux Thomas , Nuhn Michael , Hakenbeck Regine , Reichmann Peter
Published: August 2007

The production of bacteriocins can be favorable for colonization of the host by eliminating other bacterial species that share the same environment. InStreptococcus pneumoniae, thepnc(blp) locus encoding putative bacteriocins, immunity, and export proteins is controlled by a two-component system similar to thecomCDEsystem required for the induction of genetic competence. A detailed comparison of thepncclusters of four genetically distinct isolates confirmed the great plasticity of this locus and documented several repeat sequences. Members of the multiple-antibiotic-resistant Spain23F-1 clone, one member of the Spain9V-3 clone, sensitive 23F strain 2306, and the TIGR4 strain produced bactericidal substances active against other gram-positive bacteria and in some cases againstS. pneumoniaeas well. However, other strains did not show activity against the indicator strains despite the presence of a bacteriocin cluster, indicating that other factors are required for bacteriocin activity. Analysis of strain 2306 and mutant derivatives of this strain confirmed that bacteriocin production was dependent on the two-component regulatory system and genes involved in bacteriocin transport and processing. At least one other bacteriocin gene,pncE, is located elsewhere on the chromosome and might contribute to the bacteriocin activity of this strain.
Induction of RpoS Degradation by the Two-Component System Regulator RstA in
Salmonella enterica
Authors: Cabeza María L. , Aguirre Andrés , Soncini Fernando C. , Véscovi Eleonora García
Published: August 2007

Bacterial survival in diverse and changing environments relies on the accurate interplay between different regulatory pathways, which determine the design of an adequate adaptive response. The proper outcome depends on a precise gene expression profile generated from the finely tuned and concerted action of transcriptional factors of distinct regulatory hierarchies.
Salmonella enterica
serovar Typhimurium harbors multiple regulatory systems that are crucial for the bacterium to cope with harsh extra- and intracellular environments. In this work, we found that the expression of
Salmonella
RstA, a response regulator from the two-component system family, was able to downregulate the expression of three RpoS-controlled genes (
narZ
,
spvA
, and
bapA
). Furthermore, this downregulation was achieved by a reduction in RpoS cellular levels. The alternative sigma factor RpoS is critical for bacterial endurance under the most-stressful conditions, including stationary-phase entrance and host adaptation. Accordingly, RpoS cellular levels are tightly controlled by complex transcriptional, translational, and posttranslational mechanisms. The analysis of each regulatory step revealed that in
Salmonella
, RstA expression was able to promote RpoS degradation independently of the MviA-ClpXP proteolytic pathway. Additionally, we show that RstA is involved in modulating
Salmonella
biofilm formation. The fact that the RpoS-modulated genes affected by RstA expression have previously been demonstrated to contribute to
Salmonella
pathogenic traits, which include biofilm-forming capacity, suggests that under yet unknown conditions, RstA may function as a control point of RpoS-dependent pathways that govern
Salmonella
virulence.
The Circadian Clock-Related Gene
pex
Regulates a Negative
cis
Element in the
kaiA
Promoter Region
Authors: Kutsuna Shinsuke , Kondo Takao , Ikegami Haruki , Uzumaki Tatsuya , Katayama Mitsunori , Ishiura Masahiro
Published: August 2007

In the cyanobacterium
Synechococcus
sp. strain PCC 7942, a circadian clock-related gene,
pex
, was identified as the gene prolonging the period of the clock. A PadR domain, which is a newly classified transcription factor domain, and the X-ray crystal structure of the Pex protein suggest a role for Pex in transcriptional regulation in the circadian system. However, the regulatory target of the Pex protein is unknown. To determine the role of Pex, we monitored bioluminescence rhythms that reported the expression activity of the
kaiA
gene or the
kaiBC
operon in
pex
deficiency,
pex
constitutive expression, and the wild-type genotype. The expression of
kaiA
in the
pex
-deficient or constitutive expression genotype was 7 or 1/7 times that of the wild type, respectively, suggesting that
kaiA
is the target of negative regulation by Pex. In contrast, the expression of the
kaiBC
gene in the two
pex
-related genotypes was the same as that in the wild type, suggesting that Pex specifically regulates
kaiA
expression. We used primer extension analysis to map the transcription start site for the
kaiA
gene 66 bp upstream of the translation start codon. Mapping with deletion and base pair substitution of the
kaiA
upstream region revealed that a 5-bp sequence in this region was essential for the regulation of
kaiA
. The repression or constitutive expression of the
kaiA
transgene caused the prolongation or shortening of the circadian period, respectively, suggesting that the Pex protein changes the period via the negative regulation of
kaiA
.
The Motors Powering A-Motility in
Myxococcus xanthus
Are Distributed along the Cell Body
Authors: Sliusarenko Oleksii , Zusman David R. , Oster George
Published: August 2007

Two models have been proposed to explain the adventurous gliding motility of
Myxococcus xanthus
: (i) polar secretion of slime and (ii) an unknown motor that uses cell surface adhesion complexes that form periodic attachments along the cell length. Gliding movements of the leading poles of cephalexin-treated filamentous cells were observed but not equivalent movements of the lagging poles. This demonstrates that the adventurous-motility motors are not confined to the rear of the cell.
The Extension of the Fourth Transmembrane Helix of the Sensor Kinase KdpD ofEscherichia coliIs Involved in Sensing
Authors: Zimmann Petra , Steinbrügge Anne , Schniederberend Maren , Jung Kirsten , Altendorf Karlheinz
Published: August 2007

The KdpD sensor kinase and the KdpE response regulator control expression of thekdpFABCoperon coding for the KdpFABC high-affinity K+transport system ofEscherichia coli. In search of a distinct part of the input domain of KdpD which is solely responsible for K+sensing, sequences ofkdpDencoding the transmembrane region and adjacent N-terminal and C-terminal extensions were subjected to random mutagenesis. Nine KdpD derivatives were identified that had lost tight regulation ofkdpFABCexpression. They all carried single amino acid replacements located in a region encompassing the fourth transmembrane helix and the adjacent arginine cluster of KdpD. All mutants exhibited high levels ofkdpFABCexpression regardless of the external K+concentration. However, 3- to 14-fold induction was observed under extreme K+-limiting conditions and in response to an osmotic upshift when sucrose was used as an osmolyte. These KdpD derivatives were characterized by a reduced phosphatase activity in comparison to the autokinase activity in vitro, which explains constitutive expression. Whereas for wild-type KdpD the autokinase activity and also, in turn, the phosphotransfer activity to KdpE were inhibited by increasing concentrations of K+, both activities were unaffected in the KdpD derivatives. These data clearly show that the extension of the fourth transmembrane helix encompassing the arginine cluster is mainly involved in sensing both K+limitation and osmotic upshift, which may not be separated mechanistically.
The
sbcDC
Locus Mediates Repression of Type 5 Capsule Production as Part of the SOS Response in
Staphylococcus aureus
Authors: Chen Zhongyi , Luong Thanh T. , Lee Chia Y.
Published: August 2007

Most strains of
Staphylococcus aureus
produce one type of capsular polysaccharide that belongs to either type 5 or type 8. The production of these capsules has been shown to be regulated by various regulators. Here we report that the
sbcD
and
sbcC
genes are involved in the repression of type 5 capsule production. Chromosomal deletions in the
sbcDC
genes resulted in increased capsule promoter activity, capsule gene transcripts, and capsule production. The survival rates of the
sbcDC
deletion mutant were reduced upon UV irradiation compared to those for the wild-type strain Newman, suggesting that the genes are involved in DNA repair in
S. aureus
. The two genes were organized as an operon and were expressed very early in the exponential growth phase. A subinhibitory concentration of ciprofloxacin or mitomycin C induced
sbcDC
transcription but repressed the capsule promoter activity, suggesting that the
sbcDC
genes and the capsule genes are part of the SOS regulon. By reporter gene fusion and Northern blotting, we found that
sbcDC
regulated capsule by downregulating
arl
and
mgr
. Further genetic studies indicate that
sbcDC
functions upstream of
arl
and
mgr
in capsule regulation. Collectively, our results indicate that
sbcDC
, upon the SOS response, represses type 5 capsule production through an
arl
-
mgr
pathway. To our knowledge, this is the first demonstration that an SbcDC homolog was involved in transcriptional regulation.
Comparison of the BD GeneOhm VanR Assay to Culture for Identification of Vancomycin-Resistant Enterococci in Rectal and Stool Specimens
Authors: Stamper Paul D. , Cai Mian , Lema Clara , Eskey Kim , Carroll Karen C.
Published: August 2007

Active screening for vancomycin-resistant enterococci (VRE) in rectal and stool specimens has been recommended to limit the spread of antimicrobial resistance within certain high-risk populations. Directly from 502 rectal swabs and stool specimens, we evaluated the diagnostic performance of the BD GeneOhm VanR assay (BD GeneOhm, San Diego, CA), a rapid real-time PCR test that detects the presence of
vanA
and/or
vanB
genes. The VanR assay was compared to culture consisting of both bile-esculin-azide agar with 6 μg/ml vancomycin (BEAV agar) (BD Diagnostics, Sparks, MD) and BEAV broth with 8 μg/ml vancomycin (Hardy Diagnostics, Santa Maria, CA). Enterococci were identified to the species level using standard biochemical tests and a Phoenix automated microbiology system (BD Diagnostics, Sparks, MD). The susceptibility of the enterococci to vancomycin and teicoplanin was determined using an Etest (AB Biodisk, Solna, Sweden). VRE were initially isolated from 147 cultures, and the VanR assay detected 142 of the 147 positive cultures for a sensitivity of 96.6%. The specificity was 87.0% (309/355) largely due to false positives seen with the
vanB
portion of the assay. The sensitivity when testing rectal swabs was 98.3%, and the sensitivity for stool samples was 95.4% (
P
= 0.643). The specificity of rectal swabs was comparable to that of the stool specimens (87.5% and 86.5%, respectively). When used only to detect VanA resistance, the VanR assay was 94.4% (136/144) sensitive and 96.4% (345/358) specific, with positive and negative predictive values of 91.3% and 97.7%, respectively. In summary, the BD GeneOhm VanR assay is a good screening test for VRE in our population of predominantly
vanA
-colonized patients. However, patient samples testing only
vanB
positive should be confirmed by another method for the presence of VRE.
Quality of neonatal care and outcome
Authors: Acolet D
Published: August 2007

High quality of care in neonatology implies providing an appropriate level of care to well newborn babies as well as more specialised care for the few babies who need it. Audit, surveillance and outcome studies may not always capture the complexity of quality of care and its contribution to outcome, and a more focused approach to standards of care evaluation may be required. Future progress in this field in the UK would benefit from a more coordinated approach from different organisations to bring together expertise in large database, management and analysis, audit and a national profile for feedback, evidence-based guidelines and guidelines development skills, expertise in the practice of changes together with the promotion by credible perinatal authorities of clinical practice.
Calcification in breast lesions: pathologists’ perspective
Authors: Tse G M , Tan P-H , Pang A L M , Tang A P Y , Cheung H S
Published: August 2007

Evaluation of calcification in breast lesions is a major assessment criterion for breast mammography. The morphology and distribution of the calcification are related to the histology of the lesions. Radiologically, calcifications can be divided into: benign; intermediate concern; and higher probability of malignancy according to the morphology. Different pathological entities may give rise to different calcifications. Fibrocystic changes may give rise to milk of calcium or teacup type calcification, or small calcifications occurring in a cluster. Fibroadenoma may be associated with large popcorn like calcifications, and sclerosing adenosis may have fine, punctate or granular calcifications. Fat necrosis may give rise to egg shell calcification. Precursor malignant lesions give rise to benign to indeterminate type calcifications, and may occasionally be associated with malignant type calcifications. For malignant lesions, ductal carcinoma in situ and invasive duct carcinoma may be associated with large irregular, rod or V shaped, pleomorphic or branching type calcifications that follow the distribution of the duct. Furthermore, analysis of the characteristics of the calcifications may help to predict the tumour size and grade, and presence of invasion.
My approach to and thoughts on the typing of ovarian carcinomas
Authors: McCluggage W G
Published: August 2007

Ovarian carcinomas of epithelial type comprise a heterogeneous group of neoplasms, each with a different underlying pathogenesis and natural behaviour. Accurate classification of ovarian carcinomas is important since each type may be associated with a different behaviour, natural history and outcome. Precise classification is also critical to determine whether alternative therapeutic strategies are appropriate for different tumour types. Previous studies have shown significant interobserver variation in the typing of ovarian carcinomas. There are several areas where there are particular difficulties; these include the distinction between high-grade serous and endometrioid adenocarcinomas and the distinction between a true clear cell carcinoma and clear cell areas within other adenocarcinomas. This review details my approach to the typing of ovarian carcinomas. Morphological assessment, which remains the mainstay in diagnosis, can be supplemented by immunohistochemistry which, for example, is useful in the distinction between serous carcinomas (WT1 positive) and other carcinomas (generally WT1 negative). In recent years, there has been emerging new information regarding the major underlying molecular events in several types of ovarian carcinoma. This has resulted in the acceptance that there are two distinct types of ovarian serous carcinoma. These are termed low-grade and high-grade serous carcinoma, but represent two distinct tumour types rather than low-grade and high-grade variants of the same neoplasm. The integration of clinical, morphological and molecular data has resulted in a more precise classification of ovarian carcinomas and has resulted in the proposal for a broad dualistic pathway of ovarian epithelial carcinogenesis with, in general, low-grade type 1 tumours evolving from benign and borderline neoplasms through a well-defined adenoma–carcinoma sequence, and high-grade type 2 neoplasms arising from an, as yet, undefined precursor lesion.
Comparisons of self-reported and register data on sickness absence among public employees in Sweden
Authors: Voss M , Stark S , Alfredsson L , Vingård E , Josephson M
Published: August 2007

Aim:

Self-reported assessments of sickness absence are often performed in epidemiological studies. The objective of this study was to compare the number of sick-leave days according to self-reported data over 12 months with data from the employer’s register for the same period. An additional aim was to ascertain whether the self-reported information and the recorded data would show equivalent associations with self-reported general health.

Methods:

The study was based on a cohort of 4869 municipal employees in Sweden, about 80% women, who answered a questionnaire in 2001–2. The responses provided by the employees included information on number of sick-leave days and self-rated health. Data on sick-leave days, occupation and age were derived from the employers’ computerised registers. The questionnaire information on sick-leave days was compared with the corresponding information retrieved from the employer register by means of calculating sensitivity and specificity, using the employers’ data as the “gold standard”.

Results:

The annual number of sick-leave days was lower according to the self-reported information than to the register data. For women the agreement between the two sickness absence measures for no sick-leave days, 1–7 days and ≥28 days were 74%, 72% and 67%, respectively. The sensitivity of questionnaire versus register information regarding any self-reported sick-leave day was 91% and the specificity was 74%. Sensitivity and specificity for sickness absence ⩾28 days were 67% and 98%, respectively. The results for men were similar to those for women. Self-reported and recorded sickness absence were both associated with self-rated health. The odds ratios were 7.27 and 8.25, for subjects with ≥28 recorded and self-reported number of sick-leave days respectively, compared to subjects with no sickness absence.

Conclusions:

Good agreement was found between self-reported and register information on sickness absence. Self-reported data on sickness absence may be useful in common epidemiological applications.
Experimental exposure to wood smoke: effects on airway inflammation and oxidative stress
Authors: Barregard L , Sällsten G , Andersson L , Almstrand A-C , Gustafson P , Andersson M , Olin A-C
Published: August 2007

Background:

Particulate air pollution affects cardiovascular and pulmonary disease and mortality. A main hypothesis about the mechanisms involved is that particles induce inflammation in lower airways, systemic inflammation and oxidative stress.

Objectives:

To examine whether short-term exposure to wood smoke in healthy subjects affects markers of pulmonary inflammation and oxidative stress.

Methods:

13 subjects were exposed first to clean air and then to wood smoke in a chamber during 4-hour sessions, 1 week apart. The mass concentrations of fine particles at wood smoke exposure were 240–280 μg/m3, and number concentrations were 95 000–180 000/cm3, about half of the particles being ultrafine (<100 nm). Blood and breath samples were taken before and at various intervals after exposure to wood smoke and clean air and examined for exhaled nitric oxide and Clara cell protein in serum and urine, and malondialdehyde in exhaled breath condensate.

Results:

Exposure to wood smoke increased alveolar nitric oxide 3 hours post-exposure while malondialdehyde levels in breath condensate were higher both immediately after and 20 hours after exposure. Serum Clara cell protein was increased 20 hours after exposure.

Conclusions:

Wood smoke at levels that can be found in smoky indoor environments caused an inflammatory response and signs of increased oxidative stress in the respiratory tract, especially in the lower airways.
Cancer risk after cessation of asbestos exposure: a cohort study of Italian asbestos cement workers
Authors: Magnani C , Ferrante D , Barone-Adesi F , Bertolotti M , Todesco A , Mirabelli D , Terracini B
Published: August 2007

Objectives:

We aimed to study mortality for asbestos related diseases and the incidence of mesothelioma in a cohort of Italian asbestos cement workers after cessation of asbestos exposure.

Methods:

The Eternit factory operated from 1907 to 1986. The cohort included 3434 subjects active in 1950 or hired in 1950–86, ascertained from company records, without selections. Local reference rates were used for both mortality and mesothelioma incidence.

Results:

Mortality was increased in both sexes for all causes (overall 1809 observed (obs) vs 1312.3 expected (exp); p<0.01), pleural (135 obs vs 3.6 exp; p<0.01) and peritoneal (52 vs 1.9; p<0.01) malignancies and lung cancer (249 vs 103.1; p<0.01). In women, ovarian (9 vs 4.0; p<0.05) and uterine (15 vs 5.8; p<0.01) malignancies were also in excess. No statistically significant increase was found for laryngeal cancer (16 obs vs 12.2 exp). In Poisson regression analyses, the RR of death from pleural neoplasm linearly increased with duration of exposure, while it showed a curvilinear increase with latency and time since cessation of exposure. RR for peritoneal neoplasm continued to increase by latency, duration and time since cessation of exposure. RR for lung cancer showed a reduction after 15 years since cessation of exposure and levelled off after 40 years of latency.

Conclusion:

This study of a cohort of asbestos exposed workers with very long follow-up confirmed the reduction in risk of death from lung cancer after the end of exposure. It also suggested a reduction in risk for pleural mesothelioma with over 40 years of latency, while risk for peritoneal mesothelioma showed a continuing increase.
Training and other predictors of personal protective equipment use in Australian grain farmers using pesticides
Authors: MacFarlane E , Chapman A , Benke G , Meaklim J , Sim M , McNeil J
Published: August 2007

Objectives:

To investigate patterns of use of personal protective equipment (PPE) to reduce pesticide exposure in a sample of Australian farmers and also to assess the influence of possible predictive factors.

Methods:

A cross-sectional survey of 1102 farmers recruited through the Victorian Farmers Federation (VFF) was conducted. A written questionnaire was filled out by participants at VFF meetings attended by a visiting research assistant. Participants answered questions about frequency of pesticide use and PPE items they usually used when doing two different pesticide-related tasks, mixing and application, of each of four classes of pesticides. They also answered questions about personal characteristics, farm characteristics, farming activities, career and health.

Results:

Nearly all surveyed farmers had ever used pesticides, and over 87% had used Herbicides or Animal Health Products in the previous 12 months. Non-use of PPE was frequently reported, with up to 10–40% of farmers routinely using no PPE at all when using pesticides. Across all pesticide classes, PPE use was higher for pesticide mixing than for application. In multivariate analyses PPE use appeared to be most strongly associated with younger age and farm chemical training.

Conclusions:

PPE use across all pesticide classes was poor, indicating the possibility of clinically significant pesticide exposure in many farmers. Given that PPE use was found to be associated with farm chemical training, the authors suggest that training is likely to be an important intervention for reducing farmers’ pesticide exposure. Poor uptake of farm chemical training by farmers and the aging farming workforce are causes for concern in the light of these findings.
Role of maximum rate of depolarization in predicting action potential duration during ventricular fibrillation
Authors: Huang Jian , Cheng Kang-An , Dosdall Derek J. , Smith William M. , Ideker Raymond E.
Published: August 2007

During ventricular fibrillation (VF) only 39% of the variation in action potential duration (APD) is accounted for by the previous diastolic interval [DI( n−1)], i.e., restitution, and the previous APD [APD( n−1)], i.e., memory. We tested the hypothesis that a characteristic of the AP upstroke, the maximum rate of depolarization ( V̇max), also helps account for its APD. A floating microelectrode was used to make transmembrane recordings at 16,000 samples/s from the anterior left ventricular wall during four 20-s episodes of VF in each of six pigs. V̇max, time from V̇max to 60% repolarization (APD60), and DI were calculated throughout all episodes. Stepwise linear regression was used to determine how well each APD60 (APD60 n) was predicted by V̇max of that AP, the four previous DIs ( n−1, n − 2, n − 3, n − 4), and the three previous APD60s ( n−1, n − 2, n − 3). V̇max entered in the regression equation significantly more often (86% of VF episodes) than either APD( n−1) (47% of episodes) or DI( n−1) (58% of episodes). When these three variables entered first or second, their coefficients were almost always positive, consistent with a longer APD associated with 1) a larger V̇max, 2) a longer APD( n−1), and 3) a longer DI( n−1). R2 of the regression for all entered variables was 0.51 ± 0.01 (mean ± SD). During the first 20 s of VF in swine, V̇max is a more important determinant of APD than the previous DI (restitution) or the previous APD (memory). All variables together account for only one-half of APD variation during VF.
Genomic modulation of mitochondrial respiratory genes in the hypertrophied heart reflects adaptive changes in mitochondrial and contractile function
Authors: Zungu Makhosazane , Alcolea Maria Pilar , García-Palmer Francisco José , Young Martin E. , Essop M. Faadiel
Published: August 2007

We hypothesized the coordinate induction of mitochondrial regulatory genes in the hypertrophied right ventricle to sustain mitochondrial respiratory capacity and contractile function in response to increased load. Wistar rats were exposed to hypobaric hypoxia (11% O2) or normoxia for 2 wk. Cardiac contractile and mitochondrial respiratory function were separately assessed for the right and left ventricles. Transcript levels of several mitochondrial regulators were measured. A robust hypertrophic response was observed in the right (but not left) ventricle in response to hypobaric hypoxia. Mitochondrial O2consumption was increased in the right ventricle, while proton leak was reduced vs. normoxic controls. Citrate synthase activity and mitochondrial DNA content were significantly increased in the hypertrophied right ventricle, suggesting higher mitochondrial number. Transcript levels of nuclear respiratory factor-1, peroxisome proliferator-activated receptor-γ-coactivator-1α, cytochrome oxidase (COX) subunit II, and uncoupling protein-2 (UCP2) were coordinately induced in the hypertrophied right ventricle following hypoxia. UCP3 transcript levels were significantly reduced in the hypertrophied right ventricle vs. normoxic controls. Exposure to chronic hypobaric hypoxia had no significant effects on left ventricular mitochondrial respiration or contractile function. However, COXIV and UCP2 gene expression were increased in the left ventricle in response to chronic hypobaric hypoxia. In summary, we found coordinate induction of several genes regulating mitochondrial function and higher mitochondrial number in a model of physiological right ventricular hypertrophy, linking the efficiency of mitochondrial oxidative phosphorylation and respiratory function to sustained contractile function in response to the increased load.
Impairment of sympathetic baroreceptor reflexes in obese Zucker rats
Authors: Schreihofer Ann M. , Mandel Daniel A. , Mobley Susan C. , Stepp David W.
Published: August 2007

Adult obese Zucker rats (OZRs) have elevated sympathetic vasomotor tone and arterial pressure (AP) with blunted baroreflex-mediated changes in heart rate (HR) compared with adult lean Zucker rats (LZRs). The present study examined whether compromised cardiac baroreflexes are indicative of attenuated sympathetic responses. In addition, because juvenile OZRs have a normal mean AP, we determined whether baroreflexes are fully functional prior to hypertension. At 13 wk, adult OZRs had an elevated baseline mean AP compared with LZRs (137 ± 3 vs. 123 ± 5 mmHg, P < 0.05) under urethane anesthesia. Phenylephrine-induced increases in AP evoked smaller inhibitions of splanchnic sympathetic nerve activity (SNA) and HR in OZRs compared with LZRs. In addition, sympathoexcitatory responses to nitroprusside-induced hypotension were also blunted in OZRs. Sigmoid analysis revealed a decreased gain, a higher mean AP at the midpoint of the curve (AP50), and a reduced range of changes in SNA in OZRs. In contrast, at 7 wk of age, although juvenile OZRs weighed more than LZRs (313 ± 13 vs. 204 ± 4 g, P < 0.05), mean AP was comparable in both groups (122 ± 5 vs. 121 ± 4 mmHg, not significant). In these rats, rapid changes in AP evoked comparable changes in SNA and HR in OZRs and LZRs. Sigmoid analysis revealed that, although the gain of the reflex was blunted in OZRs ( P < 0.05), the mean AP50 and range of changes in SNA were comparable in OZRs and LZRs. Together, these data indicate that in adult OZRs, sympathetic responses to acute changes in AP are smaller than those observed in adult LZRs and that impairment of baroreceptor reflexes in OZR is not limited to the regulation of HR but extends to sympathetic vasomotor control. In addition, most of these deficits in baroreflex control of SNA develop in adulthood long after the onset of obesity and when other deficits in cardiovascular regulation are present.
Constitutive NADPH oxidase and increased mitochondrial respiratory chain activity regulate chemokine gene expression
Authors: Tephly Linda A. , Carter A. Brent
Published: August 2007

Alveolar macrophages, which generate high levels of reactive oxygen species, especially O2•−, are involved in the recruitment of neutrophils to sites of inflammation and injury in the lung, and the generation of chemotactic proteins triggers this cellular recruitment. In this study, we asked whether O2•−generation in alveolar macrophages had a role in the expression of chemokines. Specifically, we hypothesized that O2•−generation is necessary for chemokine expression in alveolar macrophages after TNF-α stimulation. We found that alveolar macrophages have high constitutive NADPH oxidase activity that was not increased by TNF-α, but TNF-α increased the activity of the mitochondrial respiratory chain. In addition, the mitochondrial respiratory chain increased O2•−generation if the NADPH oxidase was inhibited. O2•−generation was necessary for macrophage inflammatory protein-2 (MIP-2) gene expression, because inhibition of NADPH oxidase or the mitochondrial respiratory chain or overexpression of Cu,Zn-superoxide dismutase significantly inhibited expression of MIP-2. TNF-α activated the ERK MAP kinase, and ERK activity was essential for chemokine gene expression. In addition, overexpression of the MEK1→ERK pathway significantly increased IL-8 expression, and a small interfering RNA to the NADPH oxidase inhibited ERK- and TNF-α-induced chemokine expression. Collectively, these results suggest that in alveolar macrophages, O2•−generation mediates chemokine expression after TNF-α stimulation in an ERK-dependent manner.
Caveolins and intracellular calcium regulation in human airway smooth muscle
Authors: Prakash Y. S. , Thompson Michael A. , Vaa Brianna , Matabdin Ihaab , Peterson Timothy E. , He Tongrong , Pabelick Christina M.
Published: August 2007

Regulation of intracellular Ca2+concentration ([Ca2+]i) is a key factor in airway smooth muscle (ASM) tone. In vascular smooth muscle, specialized membrane microdomains (caveolae) expressing the scaffolding protein caveolin-1 are thought to facilitate cellular signal transduction. In human ASM cells, we tested the hypothesis that caveolae mediate Ca2+responses to agonist stimulation. Fluorescence immunocytochemistry with confocal microscopy, as well as Western blot analysis, was used to determine that agonist receptors (M3muscarinic, bradykinin, and histamine) and store-operated Ca2+entry (SOCE)-regulatory mechanisms colocalize with caveolin-1. Although caveolin-2 coexpressed with caveolin-1, caveolin-3 was absent. In fura 2-loaded ASM cells, [Ca2+]iresponses to 1 μM ACh, 10 μM histamine, and 10 nM bradykinin, as well as SOCE, were attenuated (each to a different extent) after disruption of caveolae by the cholesterol-chelating drug methyl-β-cyclodextrin. Transfection of ASM cells with 50 nM caveolin-1 small interfering RNA significantly weakened caveolin-1 expression and blunted [Ca2+]iresponses to bradykinin and histamine, as well as SOCE, but the response to ACh was less intense. These results indicate that caveolae are present in ASM and that caveolin-1 contributes to regulation of [Ca2+]iresponses to agonist.
Mechanical ventilation with 40% oxygen reduces pulmonary expression of genes that regulate lung development and impairs alveolar septation in newborn mice
Authors: Bland Richard D. , Mokres Lucia M. , Ertsey Robert , Jacobson Berit E. , Jiang Shu , Rabinovitch Marlene , Xu Liwen , Shinwell Eric S. , Zhang Feijie , Beasley Matthew A.
Published: August 2007

Mechanical ventilation with 40% oxygen reduces pulmonary expression of genes that regulate lung development and impairs alveolar septation in newborn mice. Am J Physiol Lung Cell Mol Physiol 293: , 2007. First published August 17, 2007; — Mechanical ventilation (MV) with O2-rich gas offers life-saving treatment for extremely premature infants with respiratory failure but often leads to neonatal chronic lung disease (CLD), characterized by defective formation of alveoli and blood vessels in the developing lung. We discovered that MV of 2- to 4-day-old mice with 40% O2for 8 h, compared with unventilated control pups, reduced lung expression of genes that regulate lung septation and angiogenesis (VEGF-A and its receptor, VEGF-R2; PDGF-A; and tenascin-C). MV with air for 8 h yielded similar results for PDGF-A and tenascin-C but did not alter lung mRNA expression of VEGF or VEGF-R2. MV of 4- to 6-day-old mice with 40% O2for 24 h reduced lung protein abundance of VEGF-A, VEGF-R2, PDGF-A, and tenascin-C and resulted in lung structural abnormalities consistent with evolving CLD. After MV with 40% O2for 24 h, lung volume was similar to unventilated controls, whereas distal air space size, assessed morphometrically, was greater in lungs of ventilated pups, indicative of impaired septation. Immunostaining for vimentin, which is expressed in myofibroblasts, was reduced in distal lung after 24 h of MV with 40% O2. These molecular, cellular, and structural changes occurred without detectable lung inflammation as evaluated by histology and assays for proinflammatory cytokines, myeloperoxidase activity, and water content in lung. Thus lengthy MV of newborn mice with O2-rich gas reduces lung expression of genes and proteins that are critical for normal lung growth and development. These changes yielded lung structural defects similar to those observed in evolving CLD.
Nicotine responses in hypersensitive and knockout α4 mice account for tolerance to both hypothermia and locomotor suppression in wild-type mice
Authors: Tapper Andrew R. , McKinney Sheri L. , Marks Michael J. , Lester Henry A.
Published: August 2007

Nicotinic receptors containing the α4 subunit (α4* nAChRs) have high sensitivity and are widely expressed in the central nervous system, yet their contributions to behavioral tolerance, a hallmark of nicotine dependence, are unclear. To evaluate the contribution of α4* and non-α4 nAChRs in the development of tolerance to hypothermia and locomotor suppression, α4 knockout (KO), hypersensitive Leu9′Ala α4 knock-in, and wild-type (WT) mice received daily nicotine injections, and their behaviors were compared. Repeated selective activation of α4* nAChRs in Leu9′Ala mice produced profound tolerance to hypothermia over 7 days, whereas no tolerance was observed in α4 KO animals. The summed time course and temperature response (after appropriate normalizations) from these two mutant mouse strains resembled the time course of WT tolerance. In addition, daily selective activation of α4* nAChRs elicited locomotor activation in Leu9′Ala mice, but nicotine suppressed activity in α4 KO mice and this did not change with daily drug exposure. Again, appropriately combined responses from the two mutant strains resembled the biphasic nicotine-induced activity in WT animals. Thus, by analyzing nicotinic responses in two complementary mouse lines, one lacking α4* nAChRs, the other expressing hypersensitive α4* nAChRs, one can accurately separate non-α4 nAChR responses from α4 nAChR responses, and one can also account for WT tolerance to both hypothermia and locomotor suppression. Our study suggests a new paradigm for bridging the gap between genetic manipulation of a single receptor and whole animal behavioral studies and shows that activation of α4* nAChRs is both necessary and sufficient for the expression of tolerance.