bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Functional
mob
Regions in
Rhizobium etli
: Evidence for Self-Transmissibility of the Symbiotic Plasmid pRetCFN42d
Authors: Pérez-Mendoza Daniel , Domínguez-Ferreras Ana , Muñoz Socorro , Soto María José , Olivares José , Brom Susana , Girard Lourdes , Herrera-Cervera José A. , Sanjuán Juan
Published: August 2004

An approach originally designed to identify functional origins of conjugative transfer (
oriT
or
mob
) in a bacterial genome (J. A. Herrera-Cervera, J. M. Sanjuán-Pinilla, J. Olivares, and J. Sanjuán, J. Bacteriol. 180:4583-4590, 1998) was modified to improve its reliability and prevent selection of undesired false
mob
clones. By following this modified approach, we were able to identify two functional
mob
regions in the genome of
Rhizobium etli
CFN42. One corresponds to the recently characterized transfer region of the nonsymbiotic, self-transmissible plasmid pRetCFN42a (C. Tun-Garrido, P. Bustos, V. González, and S. Brom, J. Bacteriol. 185:1681-1692, 2003), whereas the second
mob
region belongs to the symbiotic plasmid pRetCFN42d. The new transfer region identified contains a putative
oriT
and a typical conjugative (
tra
) gene cluster organization. Although pRetCFN42d had not previously been shown to be self-transmissible, mobilization of cosmids containing this
tra
region required the presence of a wild-type pRetCFN42d in the donor cell; the presence of multiple copies of this
mob
region in CFN42 also promoted conjugal transfer of the Sym plasmid pRetCFN42d. The overexpression of a small open reading frame, named
yp028
, located downstream of the putative relaxase gene
traA
, appeared to be responsible for promoting the conjugal transfer of the
R. etli
pSym under laboratory conditions. This
yp028
-dependent conjugal transfer required a wild-type pRetCFN42d
traA
gene. Our results suggest for the first time that the
R. etli
symbiotic plasmid is self-transmissible and that its transfer is subject to regulation. In wild-type CFN42, pRetCFN42d
tra
gene expression appears to be insufficient to promote plasmid transfer under standard laboratory conditions; gene
yp028
may play some role in the activation of conjugal transfer in response to as-yet-unknown environmental conditions.
ThebzdGene Cluster, Coding for Anaerobic Benzoate Catabolism, inAzoarcussp. Strain CIB
Authors: Barragán María J. López , Carmona Manuel , Zamarro María T. , Thiele Bärbel , Boll Matthias , Fuchs Georg , García José L. , Díaz Eduardo
Published: August 2004

We report here that thebzdgenes for anaerobic benzoate degradation inAzoarcussp. strain CIB are organized as two transcriptional units, i.e., a benzoate-inducible catabolic operon,bzdNOPQMSTUVWXYZA, and a gene,bzdR, encoding a putative transcriptional regulator. The last gene of the catabolic operon,bzdA, has been expressed inEscherichia coliand encodes the benzoate-coenzyme A (CoA) ligase that catalyzes the first step in the benzoate degradation pathway. The BzdA enzyme is able to activate a wider range of aromatic compounds than that reported for other previously characterized benzoate-CoA ligases. The reduction of benzoyl-CoA to a nonaromatic cyclic intermediate is carried out by a benzoyl-CoA reductase (bzdNOPQgene products) detected inAzoarcussp. strain CIB extracts. ThebzdW,bzdX, andbzdYgene products show significant similarity to the hydratase, dehydrogenase, and ring-cleavage hydrolase that act sequentially on the product of the benzoyl-CoA reductase in the benzoate catabolic pathway ofThauera aromatica. Benzoate-CoA ligase assays and transcriptional analyses based onlacZ-reporter fusions revealed that benzoate degradation inAzoarcussp. strain CIB is subject to carbon catabolite repression by some organic acids, indicating the existence of a physiological control that connects the expression of thebzdgenes to the metabolic status of the cell.
Mycoplasma hyopneumoniae
p65 Surface Lipoprotein Is a Lipolytic Enzyme with a Preference for Shorter-Chain Fatty Acids
Authors: Schmidt Jono A. , Browning Glenn F. , Markham Philip F.
Published: August 2004

Mycoplasma hyopneumoniae
is the most significant bacterial pathogen of the respiratory tract of swine. p65 is an immunodominant surface lipoprotein of
M. hyopneumoniae
that is specifically recognized during disease. Analysis of the translated amino acid sequence of the gene encoding p65 revealed similarity to the GDSL family of lipolytic enzymes. To examine the lipolytic activity of p65, the gene was cloned and expressed in
Escherichia coli
after truncation of the prokaryotic lipoprotein signal sequence and mutagenesis of the mycoplasma TGA tryptophan codons. After treatment with thrombin, the recombinant glutathione
S
-transferase (GST)-p65 protein yielded a 66-kDa fusion protein cleavage product corresponding in size to the mature p65 protein. The esterase activity of recombinant GST-p65 was indicated by the formation of a cleared zone on tributyrin agar plates and the hydrolysis of
p
-nitrophenyl esters of caproate (pNPC) and
p
-nitrophenyl esters of palmitate (pNPP). Lipase activity was indicated by the hydrolysis of the artificial triglyceride 1,2-
O
-dilauryl-
rac
-glycero-3-glutaric acid resorufin ester. Using pNPC and pNPP as substrates, recombinant GST-p65 had optimal activity between pHs 9.2 and 10.2 and at a temperature higher than 39°C. Calcium ions did not increase the activity of recombinant GST-p65. Rabbit anti-p65 antibodies inhibited the activity of recombinant GST-p65 and also inhibited the growth of
M. hyopneumoniae
in vitro. Examination of the kinetic parameters of recombinant GST-p65 for the hydrolysis of pNPC and pNPP indicated a preference for the shorter fatty acid chain of pNPC. The physiological and/or pathogenic role of mycoplasma lipolytic enzymes has not been determined, but they are likely to play an important role in mycoplasmas' nutritional requirements for long-chain fatty acids and may reduce the function of lung surfactants in mycoplasma-induced respiratory diseases. This is the first report of the lipolytic activity of a lipid-modified surface immunogen of a mycoplasma.
Worldwide Genetic Relationships among
Francisella tularensis
Isolates Determined by Multiple-Locus Variable-Number Tandem Repeat Analysis
Authors: Johansson Anders , Farlow Jason , Larsson Pär , Dukerich Meghan , Chambers Elias , Byström Mona , Fox James , Chu May , Forsman Mats , Sjöstedt Anders , Keim Paul
Published: August 2004

The intracellular bacterium
Francisella tularensis
is the causative agent of tularemia and poses a serious threat as an agent of bioterrorism. We have developed a highly effective molecular subtyping system from 25 variable-number tandem repeat (VNTR) loci. In our study, multiple-locus VNTR analysis (MLVA) was used to analyze genetic relationships and potential population structure within a global collection of 192
F. tularensis
isolates, including representatives from each of the four subspecies. The VNTR loci displayed between 2 and 31 alleles with Nei's diversity values between 0.05 and 0.95. Neighbor-joining cluster analysis of VNTR data revealed 120 genotypes among the 192
F. tularensis
isolates, including accurate subspecies identification.
F. tularensis
subsp.
tularensis
(type A) isolates showed great diversity at VNTR loci, while
F. tularensis
subsp.
holarctica
(type B) isolates showed much lower levels despite a much broader geographical prevalence. The resolution of two distinct clades within
F. tularensis
subsp.
tularensis
(designated A.I and A.II) revealed a previously unrecognized genetic division within this highly virulent subspecies.
F. tularensis
subsp.
holarctica
appears to have recently spread globally across continents from a single origin, while
F. tularensis
subsp.
tularensis
has a long and complex evolutionary history almost exclusively in North America. The sole non-North American type A isolates (Slovakian) were closely related to the SCHU S4 strain. Significant linkage disequilibrium was detected among VNTR loci of
F. tularensis
consistent with a clonal population structure. Overall, this work greatly augments the study of tularemia ecology and epidemiology, while providing a framework for future forensic analysis of
F. tularensis
isolates.
Hypercyst Mutants in
Rhodospirillum centenum
Identify Regulatory Loci Involved in Cyst Cell Differentiation
Authors: Berleman James E. , Hasselbring Benjamin M. , Bauer Carl E.
Published: August 2004

Rhodospirillum centenum
is a purple photosynthetic bacterium that forms resting cyst cells when starved for nutrients. In this study, we demonstrate that chalcone synthase gene (
chsA
) expression is developmentally regulated, with expression of
chsA
increasing up to 86-fold upon induction of the cyst developmental cycle. Screening for mini-Tn
5
-induced mutants that exhibit elevated
chsA
::
lacZ
expression has led to the isolation of a set of
R. centenum
mutants that display increased
chsA
gene expression concomitant with constitutive induction of the cyst developmental cycle. These “hypercyst” mutants have lost the ability to regulate cyst cell formation in response to nutrient availability. Sequence analysis indicates that the mini-Tn
5
-disrupted genes code for a variety of factors, including metabolic enzymes and a large set of potential regulatory factors, including four gene products with homology to histidine sensor kinases and three with homology to response regulators. Several of the disrupted genes also have sequence similarity to
che
-like signal transduction components.
Complete Genome Sequence ofRickettsia typhiand Comparison with Sequences of Other Rickettsiae
Authors: McLeod Michael P. , Qin Xiang , Karpathy Sandor E. , Gioia Jason , Highlander Sarah K. , Fox George E. , McNeill Thomas Z. , Jiang Huaiyang , Muzny Donna , Jacob Leni S. , Hawes Alicia C. , Sodergren Erica , Gill Rachel , Hume Jennifer , Morgan Maggie , Fan Guangwei , Amin Anita G. , Gibbs Richard A. , Hong Chao , Yu Xue-jie , Walker David H. , Weinstock George M.
Published: August 2004

Rickettsia typhi, the causative agent of murine typhus, is an obligate intracellular bacterium with a life cycle involving both vertebrate and invertebrate hosts. Here we present the complete genome sequence ofR. typhi(1,111,496 bp) and compare it to the two published rickettsial genome sequences:R. prowazekiiandR. conorii. We identified 877 genes inR. typhiencoding 3 rRNAs, 33 tRNAs, 3 noncoding RNAs, and 838 proteins, 3 of which are frameshifts. In addition, we discovered more than 40 pseudogenes, including the entire cytochromecoxidase system. The three rickettsial genomes share 775 genes: 23 are found only inR. prowazekiiandR. typhi, 15 are found only inR. conoriiandR. typhi, and 24 are unique toR. typhi. Although most of the genes are colinear, there is a 35-kb inversion in gene order, which is close to the replication terminus, inR. typhi, compared toR. prowazekiiandR. conorii. In addition, we found a 124-kbR. typhi-specific inversion, starting 19 kb from the origin of replication, compared toR. prowazekiiandR. conorii. Inversions in this region are also seen in the unpublished genome sequences ofR. sibiricaandR. rickettsii, indicating that this region is a hot spot for rearrangements. Genome comparisons also revealed a 12-kb insertion in theR. prowazekiigenome, relative toR. typhiandR. conorii, which appears to have occurred after the typhus (R. prowazekiiandR. typhi) and spotted fever (R. conorii) groups diverged. The three-way comparison allowed further in silico analysis of the SpoT split genes, leading us to propose that the stringent response system is still functional in these rickettsiae.
The ClpP Peptidase Is the Major Determinant of Bulk Protein Turnover in
Bacillus subtilis
Authors: Kock Holger , Gerth Ulf , Hecker Michael
Published: August 2004

Measurements of overall protein degradation rates in wild-type and
clpP
mutant
Bacillus subtilis
cells revealed that stress- or starvation-induced bulk protein turnover depends virtually exclusively on the ClpP peptidase. ClpP is also essential for intracellular protein quality control, and in its absence newly synthesized proteins were highly prone to aggregation even at 37°C. Proteomic comparisons between the wild type and a Δ
clpP
mutant showed that the absence of ClpP leads to severe perturbations of “normal” physiology, complicating the detection of ClpP substrates. A pulse-chase two-dimensional gel approach was therefore used to compare wild-type and
clpP
mutant cultures that had been radiolabeled in mid-exponential phase, by quantifying changes in relative spot intensities with time. The results showed that overall proteolysis is biased toward proteins with vegetative functions which are no longer required (or are required at lower levels) in the nongrowing state. The identified substrate candidates for ClpP-dependent degradation include metabolic enzymes and aminoacyl-tRNA synthetases. Some substrate candidates catalyze the first committed step of certain biosynthetic pathways. Our data suggest that ClpP-dependent proteolysis spans a broad physiological spectrum, with regulatory processing of key metabolic components and regulatory proteins on the one side and general bulk protein breakdown at the transition from growing to nongrowing phases on the other.
The
htx
and
ptx
Operons of
Pseudomonas stutzeri
WM88 Are New Members of the Pho Regulon
Authors: White Andrea K. , Metcalf William W.
Published: August 2004

The
htx
and
ptx
operons of
Pseudomonas stutzeri
WM88 allow for the use of the inorganic reduced phosphorus (P) compounds hypophosphite (P valence, +1) and phosphite (P valence, +3) as sole P sources. To support the proposed in vivo role for the
htx
and
ptx
operons, namely the use of phosphite and hypophosphite as alternative P sources, we used reporter gene fusions to examine their expression levels with respect to various P conditions. Expression of the
htx
and
ptx
operons was induced up to 17- and 22-fold, respectively, in cultures grown under phosphate starvation conditions relative to expression in medium with excess phosphate (P
i
). However, the presence of the reduced P substrate hypophosphite, phosphite, or methylphosphonate, in addition to excess P
i
, did not result in an increase in the expression of either operon. To provide further support for a role of the
htx
and
ptx
operons in P
i
acquisition, we identified
P. stutzeri phoBR
homologs and constructed deletion mutants. Induction of the
htx
and
ptx
reporter gene fusions in response to growth on limiting P
i
was abolished in Δ
phoB
, Δ
phoR
, and Δ
phoBR
mutants, demonstrating that
htx
and
ptx
expression is
phoBR
dependent. The putative LysR-type regulator encoded by
ptxE
has no apparent role in the expression of the
htx
and
ptx
operons, as no effect was observed on the level of induction of either operon in a Δ
ptxE
mutant.
The
Escherichia coli argU10
(Ts) Phenotype Is Caused by a Reduction in the Cellular Level of the
argU
tRNA for the Rare Codons AGA and AGG
Authors: Sakamoto Kensaku , Ishimaru Satoshi , Kobayashi Takatsugu , Walker James R. , Yokoyama Shigeyuki
Published: August 2004

The
Escherichia coli argU10
(Ts) mutation in the
argU
gene, encoding the minor tRNA
Arg
species for the rare codons AGA and AGG, causes pleiotropic defects, including growth inhibition at high temperatures, as well as the Pin phenotype at 30°C. In the present study, we first showed that the codon selectivity and the arginine-accepting activity of the
argU
tRNA are both essential for complementing the temperature-sensitive growth, indicating that this defect is caused at the level of translation. An in vitro analysis of the effects of the
argU10
(Ts) mutation on tRNA functions revealed that the affinity with elongation factor Tu-GTP of the
argU10
(Ts) mutant tRNA is impaired at 30 and 43°C, and this defect is more serious at the higher temperature. The arginine acceptance is also impaired significantly but to similar extents at the two temperatures. An in vivo analysis of aminoacylation levels showed that 30% of the
argU10
(Ts) tRNA molecules in the mutant cells are actually deacylated at 30°C, while most of the
argU
tRNA molecules in the wild-type cells are aminoacylated. Furthermore, the cellular level of this mutant tRNA is one-tenth that of the wild-type
argU
tRNA. At 43°C, the cellular level of the
argU10
(Ts) tRNA is further reduced to a trace amount, while neither the cellular abundance nor the aminoacylation level of the wild-type
argU
tRNA changes. We concluded that the phenotypic properties of the
argU10
(Ts) mutant result from these reduced intracellular levels of the tRNA, which are probably caused by the defective interactions with elongation factor Tu and arginyl-tRNA synthetase.
Regulation of Ribosomal Protein Synthesis in
Vibrio cholerae
Authors: Allen Todd D. , Watkins Tonya , Lindahl Lasse , Zengel Janice M.
Published: August 2004

We have investigated the regulation of the S10 and
spc
ribosomal protein (r-protein) operons in
Vibrio cholerae
. Both operons are under autogenous control; they are mediated by r-proteins L4 and S8, respectively. Our results suggest that
Escherichia coli
-like strategies for regulating r-protein synthesis extend beyond the enteric members of the gamma subdivision of proteobacteria.
Characterization of the Upper Pathway Genes for Fluorene Metabolism in
Terrabacter
sp. Strain DBF63
Authors: Habe Hiroshi , Chung Jin-Sung , Kato Hiroyuki , Ayabe Yuko , Kasuga Kano , Yoshida Takako , Nojiri Hideaki , Yamane Hisakazu , Omori Toshio
Published: August 2004

Genes involved in the degradation of fluorene to phthalate were characterized in the fluorene degrader
Terrabacter
sp. strain DBF63. The initial attack on both fluorene and 9-fluorenone was catalyzed by DbfA to yield 9-fluorenol and 1,1a-dihydroxy-1-hydro-9-fluorenone, respectively. The FlnB protein exhibited activities against both 9-fluorenol and 1,1a-dihydroxy-1-hydro-9-fluorenone to produce 9-fluorenone and 2′-carboxy-2,3-dihydroxybiphenyl, respectively. FlnD is a heteromeric protein encoded by
flnD1
and ORF16, being a member of the class III two-subunit extradiol dioxygenase. FlnE was identified as a serine hydrolase for the
meta
-cleavage products that yield phthalate.
Identification of Operators and Promoters That Control SXT Conjugative Transfer
Authors: Beaber John W. , Waldor Matthew K.
Published: August 2004

Transfer of SXT, a
Vibrio cholerae
-derived integrating conjugative element that encodes multiple antibiotic resistance genes, is repressed by SetR, a λ
434
c
I-related repressor. Here we identify divergent promoters between
s086
and
setR
that drive expression of the regulators of SXT transfer. One transcript encodes the activators of transfer,
setC
and
setD
. The second transcript codes for SetR and, like the
c
I transcript of lambda, is leaderless. SetR binds to four operators located between
setR
and
s086
; the locations and relative affinities of these sites suggest a model for regulation of SXT transfer.
Analysis of Chimeric Chemoreceptors inBacillus subtilisReveals a Role for CheD in the Function of the McpC HAMP Domain
Authors: Kristich Christopher J. , Ordal George W.
Published: August 2004

Motile prokaryotes use a sensory circuit for control of the motility apparatus in which ligand-responsive chemoreceptors regulate phosphoryl flux through a modified two-component signal transduction system. The chemoreceptors exhibit a modular architecture, comprising an N-terminal sensory module, a C-terminal output module, and a HAMP domain that connects the N- and C-terminal modules and transmits sensory information between them via an unknown mechanism. The sensory circuits mediated by two chemoreceptors ofBacillus subtilishave been studied in detail. McpB is known to regulate chemotaxis towards the attractant asparagine in a CheD-independent manner, whereas McpC requires CheD to regulate chemotaxis towards the attractant proline. Although CheD is a phylogenetically widespread chemotaxis protein, there exists only a limited understanding of its function. We have constructed chimeras between McpB and McpC to probe the role of CheD in facilitating sensory transduction by McpC. We found that McpC can be converted to a CheD-independent receptor by the replacement of one-half of its HAMP domain with the corresponding sequence from McpB, suggesting that McpC HAMP domain function is complex and may require intermolecular interactions with the CheD protein. When considered in combination with the previous observation that CheD catalyzes covalent modification of the C-terminal modules ofB. subtilisreceptors, these results suggest that CheD may interact with chemoreceptors at multiple, functionally distinct sites.
Mutational Analysis of the
fruA
Promoter Region Demonstrates that C-Box and 5-Base-Pair Elements Are Important for Expression of an Essential Developmental Gene of
Myxococcus xanthus
Authors: Srinivasan D. , Kroos Lee
Published: August 2004

Myxococcus xanthu
s uses extracellular signals during development to regulate gene expression. C-signaling regulates the expression of many genes induced after 6 h into development. FruA is a protein that is necessary for cells to respond to C-signaling, but expression of the
fruA
gene does not depend on C-signaling. Yet the
fruA
promoter region has a C box and a 5-bp element, similar to the promoter regions of several C-signal-dependent genes, where these sequences are crucial. Here, we show that the C box and 5-bp elements are important for expression of
fruA
, demonstrating for the first time that these sequences play a role in the expression of a gene that does not depend on C-signaling and is required for
M. xanthus
development.
Examining the associations between physical work demands and work injury rates between men and women in Ontario, 1990–2000
Authors: Smith P M , Mustard C A
Published: August 2004

Aims:To describe the decline in injury rates between 1990 and 2000 within occupations stratified across three levels of physical demands and gender, adjusting for industry, in Canada’s largest province.

Methods:Records of injury compensation claims were obtained from the Ontario Workplace Safety & Insurance Board. The population likely to be insured by the Ontario Workplace Safety & Insurance Board was estimated from Statistics Canada’s Labour Force Survey. Injury rates were calculated by three broad levels of physical demands, separately for men and women.

Results:Injury rates decreased across each grouping of lower physical demands at work for both men and women, with the largest absolute differences in manual occupational groups (high physical demands). Occupations classified as manual (high physical demands) and mixed (moderate physical demands) showed larger differences in injury rates between genders than did non-manual (low physical demands), although the directions of these differences were not always consistent across different natures of injury classification.

Conclusions:The absolute reduction in injury rates in Ontario between 1990 and 2000 was dominated by the reduction in injury rates for men and women in manual and mixed occupations. However, not all types of injury have declined to the same extent. A large proportion of differences in injury rates between men and women can be attributed to the differential labour force participation across occupations and industries, as well as the differential tasks within occupational groups.
Primary osteoarthritis and occupation in the Quebec national health and social survey
Authors: Rossignol M
Published: August 2004

Background:The scientific evidence available is consistent in linking osteoarthritis (OA) and occupation but is lacking information regarding preventable risks in the workplace.

Aims:To explore the effect of different dimensions of physical demand in the relation between self reported OA and occupation.

Methods:Nationwide population survey of employed and self employed adults aged 25–64.

Results:Of the 11 144 workers surveyed, 3.1% (two females for one male) reported a problem with OA (any site). They reported some degree of limitations in their daily activities in a proportion that was six times higher (26.8%) than the rest of the population of the same age without OA and twice as high for absence from work in the previous year (23.8%). Of the different dimensions of risks used in the survey and controlling for age, body mass index, and smoking, “use of force with tools or machines” showed a statistically significant association with OA in males and females. In occupations significant risks of OA were identified in male unskilled labourers and skilled labourers, and in female technicians, and workers in the services sector.

Conclusions:Results of the present survey indicated that occupational stresses associated with OA may differ substantially between male and female workers and that specific risks may affect the younger workforce (25–44 years old) in some occupations, including housekeeping and other ill defined skilled and unskilled labour.
Occupational and environmental exposures and lung cancer in an industrialised area in Italy
Authors: Fano V , Michelozzi P , Ancona C , Capon A , Forastiere F , Perucci C A
Published: August 2004

Aims:To investigate the effects of occupational exposures and residence near to industrial sites on lung cancer mortality in an area in Italy.

Methods:234 cases of lung cancer and 729 controls matched by sex, age, and date of death were enrolled. Environmental exposure was evaluated using historical residence data. A geographical information system was used to compute distances from residence to pollution source (cement factory, power plants, harbour) and an average distance was computed for each subject. Odds ratios (OR) and 95% confidence intervals (CI) in a logistic regression model were used to estimate the relative risk of lung cancer associated with the risk factors (smoking habits and occupational exposure) collected by questionnaire; ORs for distances from pollution sources and from city centre were computed, adjusting for smoking habits, education, and occupation.

Results:Smoking habits (⩽10 cigarettes/day, OR = 2.28; 11–20, OR = 4.64; >20, OR = 6.61) and occupational exposure to asbestos (OR = 3.50) were significantly associated with lung cancer risk. Reported traffic level of area of residence and residence near the four sources were not associated with increased risk of lung cancer. There was a significantly increased risk for those residing outside the city centre, in the southern outskirts (OR = 1.51).

Conclusions:The increased lung cancer risk observed in the area can partly be explained by occupational exposures. The increased risk in the outskirts of the city is consistent with the results of dispersion models that indicate high levels of pollutant deposition in the same area.
Agricultural pesticide use and adenocarcinomas of the stomach and oesophagus
Authors: Lee W J , Lijinsky W , Heineman E F , Markin R S , Weisenburger D D , Ward M H
Published: August 2004

Aims:To evaluate the risk of the stomach and oesophageal adenocarcinomas associated with farming and agricultural pesticide use.

Methods:Population based case-control study in eastern Nebraska. Telephone interviews were conducted with men and women diagnosed with adenocarcinoma of the stomach (n = 170) or oesophagus (n = 137) between 1988 and 1993, and controls (n = 502) randomly selected from the same geographical area. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) for farming and for use of individual and chemical classes of insecticides and herbicides, including pesticides classified as nitrosatable (able to form N-nitroso compounds on reaction with nitrite). Non-farmers were used as the reference category for all analyses.

Results:Ever living or working on a farm, duration of farming, and size of the farm were not associated with stomach or oesophageal adenocarcinomas. There was no association for either cancer with ever-use of insecticides (stomach OR 0.9, 95% CI 0.6 to 1.4; oesophagus OR 0.7, 95% CI 0.4 to 1.1) or herbicides (stomach OR 0.9, 95% CI 0.5 to 1.4; oesophagus OR 0.7, 95% CI 0.4 to 1.2). Likewise, individual pesticides, including individual nitrosatable pesticides, were not significantly associated with risk.

Conclusions:No significant associations were found between specific agricultural pesticide exposures and the risk of stomach or oesophageal adenocarcinomas among Nebraska farmers.
A cohort study of mortality among Ontario pipe trades workers
Authors: Finkelstein M M , Verma D K
Published: August 2004

Aims:To study mortality in a cohort of members of the United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry of the United States and Canada and to compare results with two previous proportional mortality studies.

Methods:A cohort of 25 285 workers who entered the trade after 1949 was assembled from records of the international head office. Mortality was ascertained by linkage to the Canadian Mortality Registry at Statistics Canada. Standardised mortality ratios were computed using Ontario general population mortality rates as the reference.

Results:There were significant increases in lung cancer mortality rates (SMR 1.27; 95% CI 1.13 to 1.42). Increased lung cancer risk was observed among plumbers, pipefitters, and sprinkler fitters. Increased risk was observed among workers joining the Union as late as the 1970s. A random effects meta-analysis of this study and the two PMR studies found significant increases in oesophageal (RR 1.24; 95% CI 1.00 to 1.53), lung (RR 1.31; 95% CI 1.19 to 1.44), and haematological/lymphatic (RR 1.21; 95% CI 1.08 to 1.35) malignancies.

Conclusions:The mortality pattern is consistent with the effects of occupational exposure to asbestos. Increased risk due to other respiratory carcinogens such as welding fume cannot be excluded. There are substantial amounts of asbestos in place in industrial and commercial environments. The education and training of workers to protect themselves against inhalation hazards will be necessary well into the future.
Learning difficulties in children born to male UK nuclear industry employees; analysis from the nuclear industry family study
Authors: Burt A , Maconochie N , Doyle P , Roman E
Published: August 2004

There has been much debate about paternal pre-conceptual exposure to low level ionising radiation and possible increased risk of ill health among the children subsequently conceived. The prevalence of reported learning difficulties was examined in over 16 000 children born to UK nuclear industry workers, using fathers’ information on exposure from the workers’ individual employment and dosimetry records. There was no evidence that paternal exposure to low level ionising radiation at work influences the prevalence of learning difficulties in otherwise healthy children conceived after exposure.
Portal infusion of a selective serotonin reuptake inhibitor enhances hepatic glucose disposal in conscious dogs
Authors: Moore Mary Courtney , DiCostanzo Catherine A. , Dardevet Dominique , Lautz Margaret , Farmer Ben , Neal Doss W. , Cherrington Alan D.
Published: August 2004

Intraportal delivery of serotonin enhanced net hepatic glucose uptake (NHGU) during a hyperinsulinemic hyperglycemic clamp, but serotonin elevated catecholamines and can cause gastrointestinal distress. We hypothesized that the selective serotonin reuptake inhibitor (SSRI) fluvoxamine would enhance NHGU without side effects. Arteriovenous difference and tracer ([3-3H]glucose) techniques were used in conscious 42-h-fasted dogs. Experiments consisted of equilibration (−120 to −30 min), basal (−30 to 0 min), and experimental (EXP; 0–270 min) periods. During EXP, somatostatin, fourfold basal intraportal insulin, basal intraportal glucagon, and peripheral glucose (to double the hepatic glucose load) were infused. Saline (SAL) was infused intraportally during 0–90 min (P1), and fluvoxamine was infused intraportally at 0.5, 1, and 2 μg·kg−1·min−1from 90 to 150 (P2), 150 to 210 (P3), and 210 to 270 (P4) min, respectively, in the FLUV group ( n = 8). The SAL group ( n = 9) received intraportal saline during 0–270 min. NHGU in SAL was 13.9 ± 1.7 and 17.0 ± 2.0 μmol·kg−1·min−1in P3–P4, respectively, while NHGU in FLUV averaged 19.7 ± 2.8 and 26.6 ± 3.0 μmol·kg−1·min−1( P < 0.05 vs. SAL). Net hepatic carbon retention was greater ( P < 0.05) in FLUV than in SAL (17.6 ± 2.6 vs. 13.9 ± 2.7 and 23.8 ± 3.0 vs. 14.4 ± 3.3 μmol·kg−1·min−1in P3–P4, respectively), and final hepatic glycogen concentrations were 50% greater in FLUV ( P < 0.005). Nonhepatic glucose uptake was greater in SAL than in FLUV at 270 min ( P < 0.05). Catecholamine concentrations remained basal, and the animals evidenced no distress. Thus fluvoxamine enhanced NHGU and hepatic carbon storage without raising circulating serotonin concentrations or causing stress, suggesting that hepatic-targeted SSRIs might be effective in reducing postprandial hyperglycemia in individuals with diabetes or impaired glucose tolerance.
PPARγ ligands induce ER stress in pancreatic β-cells: ER stress activation results in attenuation of cytokine signaling
Authors: Weber Sarah M. , Chambers Kari T. , Bensch Kenneth G. , Scarim Anna L. , Corbett John A.
Published: August 2004

Peroxisome proliferator-activated receptor (PPAR)γ ligands are known to have anti-inflammatory properties that include the inhibition of cytokine signaling, transcription factor activation, and inflammatory gene expression. We have recently observed that increased expression of heat shock protein (HSP)70 correlates with, but is not required for, the anti-inflammatory actions of PPARγ ligands on cytokine signaling. In this study, we provide evidence that the inhibitory actions of PPARγ ligands on cytokine signaling are associated with endoplasmic reticulum (ER) stress or unfolded protein response (UPR) activation in pancreatic β-cells. 15-Deoxy-Δ12,14-prostaglandin J2, at concentrations that inhibit cytokine signaling, stimulates phosphorylation of eukaryotic initiation factor-2α, and this event is followed by a rapid inhibition of protein translation. Under conditions of impaired translation, PPARγ ligands stimulate the expression of a number of ER stress-responsive genes, such as GADD 153, BiP, and HSP70. Importantly, ER stress activation in response to PPARγ ligands or known UPR activators results in the attenuation of IL-1 and IFN-γ signaling. These findings indicate that PPARγ ligands induce ER stress, that ER stress activation is associated with an attenuation of cytokine signaling in β-cells, and that the attenuation of responsiveness to extracellular stimuli appears to be a novel protective action of the UPR in cells undergoing ER stress.
Concomitant expression of adrenomedullin and its receptor components in rat adipose tissues
Authors: Fukai Nozomi , Yoshimoto Takanobu , Sugiyama Toru , Ozawa Naoko , Sato Ryuji , Shichiri Masayoshi , Hirata Yukio
Published: August 2004

Adrenomedullin (AM) expressed by and secreted from a variety of cells plays pluripotent roles in an autocrine/paracrine fashion. The present study was undertaken to explore the expression of AM and its receptor genes in adipose tissues, their changes during the development of obesity, and the process of preadipocyte differentiation. Both mature adipocytes and stromal vascular cells constituting adipose tissue expressed AM transcript. AM and its receptor component [calcitonin receptor-like receptor and receptor activity-modifying protein-2 (CRLR/RAMP2)] mRNAs were expressed in a variety of rat adipose tissues, including epididymal, mesenteric, retroperitoneal, and subcutaneous adipose tissue. AM mRNA levels in rat and human epididymal adipose tissue were about one-tenth of those in the kidney. Steady-state mRNA levels of AM and CRLR/RAMP2 in epididymal, mesenteric, and retroperitoneal adipose tissues in rats fed a high-fat diet for 4 wk were far greater than those in rats with normal diet accompanied by increased plasma AM levels, whereas steady-state AM mRNA levels conversely decreased in other organs, such as kidney and liver. AM mRNA expressed in a mouse preadipocyte cell line (3T3-L1) transiently decreased by day 3, returned to basal level by day 6, and then increased by day 9 during preadipocyte differentiation, which paralleled AM secretion from the cells. However, the addition of either exogenous AM or AM receptor antagonist calcitonin gene-related peptide-(8–37), to block endogenous AM did not affect lipid droplet accumulation during preadipocyte differentiation. The present study demonstrates for the first time that AM and its receptor component (CRLR/RAMP2) mRNAs were concomitantly expressed in various adipose tissues, whose tissue-specific upregulation was induced during the development of obesity. These data suggest that AM may act as a new member of adipokines, although its functional role, as well as its pathophysiological significance in obesity, remains to be determined.
Cardiac myocyte apoptosis provokes adverse cardiac remodeling in transgenic mice with targeted TNF overexpression
Authors: Engel David , Peshock Ronald , Armstong Robert C. , Sivasubramanian Natarajan , Mann Douglas L.
Published: August 2004

Although cardiac myocyte apoptosis has been detected in explanted hearts from patients with end-stage dilated and ischemic cardiomyopathy, the relative contribution of apoptotic cell death to left ventricular (LV) remodeling and cardiac decompensation is not known. To determine whether progressive cardiac myocyte apoptosis contributes to the transition from a hypertrophic to a dilated cardiac phenotype that is observed in transgenic myosin heavy chain secreted TNF (MHCsTNF) mice with cardiac restricted overexpression of tumor necrosis factor (TNF), we assessed cardiac myocyte apoptosis (using a DNA ligase technique) in MHCsTNF mice and littermate control mice in relation to serial changes in LV structure, which was assessed using MRI. The prevalence of cardiac myocyte apoptosis increased progressively from 4 to 12 wk as the hearts of the MHCsTNF mice underwent the transition from a concentric hypertrophic to a dilated cardiac phenotype. Treatment of the MHCsTNF mice with the broad-based caspase inhibitor N-[(1,3-dimethylindole-2-carbonyl)-valinyl]-3-amino4-oxo-5-fluoropentanoic acid significantly decreased cardiac myocyte apoptosis and significantly attenuated LV wall thinning and adverse cardiac remodeling. Additional studies suggested that the TNF-induced decrease in Bcl-2 expression and activation of the intrinsic mitochondrial death pathway were responsible for the cardiac myocyte apoptosis observed in the MHCsTNF mice. These studies show that progressive cardiac myocyte apoptosis is sufficient to contribute to adverse cardiac remodeling in the adult mammalian heart through progressive LV wall thinning.
Role of natriuretic peptides in regulation of conduit artery distensibility
Authors: Schmitt Matthias , Qasem Ahmad , McEniery Carmel , Wilkinson Ian B. , Tatarinoff Vicki , Noble Kate , Klemes John , Payne Nicola , Frenneaux Michael P. , Cockcroft John , Avolio Albert
Published: August 2004

Arterial distensibility, assessed by the pulse-wave velocity (PWV), is an independent predictor of cardiovascular risk. We investigated whether natriuretic peptides, acting locally, modify conduit artery distensibility in vivo. All studies were conducted in anesthetized sheep ( n = 18) by using a validated ovine hindlimb model. In brief, the PWV was calculated, with the use of the foot-to-foot methodology, from two pressure waveforms recorded simultaneously with a high-fidelity dual pressure-sensing catheter placed in the common iliac artery. Drugs were infused either proximally, via the catheter to perfuse the segment of artery under study, or distally, via the sheath to control for any reflex changes in flow or sympathetic activation. First, the effects of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and c-type natriuretic peptide (CNP) were studied. Second, the role of endogenous ANP was investigated by infusing the natriuretic peptide receptor type A (NPRA)-selective receptor antagonist A71915. Third, A71915 was coinfused with ANP. Fourth, the NPRC-selective agonist cANF was infused. Infusion of CNP or des-[Gln18Ser19Gly20Leu21Gly22]-ANF-(4-23)-NH2 (cANF) had no effect on iliac PWV. However, infusion of ANP, and to a lesser degree BNP, resulted in a reduction in PWV (−9%; P < 0.01 and −6%; P < 0.05, respectively). A71915 increased iliac PWV from 2.97 ± 0.13 to 3.06 ± 0.13 m/s; P < 0.01. Coinfusion of A71915 with ANP completely abolished the effects of ANP ( P < 0.01). Importantly, ANP-BNP infusion via the sheath did not alter PWV. In conclusion, ANP, and to a lesser extent BNP, modify large artery distensibility via the NPRA receptor. Neither CNP nor cANF altered PWV, suggesting that the NPRB and NPRC receptors do not acutely influence distensibility in vivo.
Protection against ventricular arrhythmias and cardiac death using adenosine and lidocaine during regional ischemia in the in vivo rat
Authors: Canyon Sarah J. , Dobson Geoffrey P.
Published: August 2004

Despite decades of research, there are few effective ways to treat ventricular fibrillation (VF), ventricular tachycardia (VT), or cardiac ischemia that show a significant survival benefit. Our aim was to investigate the combined therapeutic effect of two common antiarrhythmic compounds, adenosine and lidocaine (AL), on mortality, arrhythmia frequency and duration, and infarct size in the rat model of regional ischemia. Sprague-Dawley rats ( n = 49) were anesthetized with pentobarbital sodium (60 mg·ml−1·kg−1 ip) and instrumented for regional coronary occlusion (30 min) and reperfusion (120 min). Heart rate, blood pressure, and a lead II electrocardiogram were recorded. Intravenous pretreatment began 5 min before ischemia and extended throughout ischemia, terminating at the start of reperfusion. After 120 min, hearts were removed for infarct size measurement. Mortality occurred in 58% of saline controls ( n = 12), 50% of adenosine only (305 μg·kg−1·min−1, n = 8), 0% in lidocaine only (608 μg·kg−1·min−1, n = 8), and 0% in AL at any dose (152, 305, or 407 μg·kg−1·min−1 adenosine plus 608 μg·kg−1·min−1 lidocaine, n = 7, 8, and 6). VT occurred in 100% of saline controls (18 ± 9 episodes), 50% of adenosine-only (11 ± 7 episodes), 83% of lidocaine-only (23 ± 11 episodes), 60% of low-dose AL (2 ± 1 episodes, P < 0.05), 57% of mid-dose AL (2 ± 1 episodes, P < 0.05), and 67% of high-dose AL rats (6 ± 3 episodes). VF occurred in 75% of saline controls (4 ± 3 episodes), 100% of adenosine-only-treated rats (3 ± 2 episodes), and 33% lidocaine-only-treated rats (2 ± 1 episodes) of the rats tested. There was no deaths and no VF in the low- and mid-dose AL-treated rats during ischemia, and only one high-dose AL-treated rat experienced VF (25.5 sec). Infarct size was lower in all AL-treated rats but only reached significance with the mid-dose treatment (saline controls 61 ± 5% vs. 38 ± 6%, P < 0.05). We conclude that a constant infusion of a solution containing AL virtually abolished severe arrhythmias and prevented cardiac death in an in vivo rat model of acute myocardial ischemia and reperfusion. AL combinational therapy may provide a primary prevention therapeutic window in ischemic and nonischemic regions of the heart.
Inhibition of tumor necrosis factor receptor-1-mediated pathways has beneficial effects in a murine model of postischemic remodeling
Authors: Ramani Ravi , Mathier Michael , Wang Ping , Gibson Gregory , Tögel Sandra , Dawson Jennifer , Bauer Anthony , Alber Sean , Watkins Simon C. , McTiernan Charles F. , Feldman Arthur M.
Published: August 2004

The aim of the present study was to investigate the importance of tumor necrosis factor (TNF)-α receptor-1 (TNFR1)-mediated pathways in a murine model of myocardial infarction and remodeling. One hundred and ninety-four wild-type (WT) and TNFR1 gene-deleted (TNFR1KO) mice underwent left coronary artery ligation to induce myocardial infarction. On days 1, 3, 7, and 42, mice underwent transesophageal echocardiography. Hearts were weighed, and the left ventricle (LV) was assayed for matrix metalloproteinase (MMP)-2 and -9 activity and for tissue inhibitor of MMP (TIMP)-1 and -2 expression. Deletion of the TNFR1 gene substantially improved survival because no deaths were observed in TNFR1KO mice versus 56.4% and 18.2% in WT males and females, respectively ( P < 0.002). At 42 days, LV remodeling, assessed by LV function (fractional area change of 31.9 ± 7.9%, 32.2 ± 7.7%, and 21.6 ± 7.1% in TNFR1KO males, TNFR1KO females, and WT females, respectively, P < 0.04), and hypertrophy (heart weight-to-body weight ratios of 5.435 ± 0.986, 5.485 ± 0.677, and 6.726 ± 0.704 mg/g, P < 0.04) were ameliorated in TNFR1KO mice. MMP-9 activity was highest at 3 days postinfarction and was highest in WT males (1.9 ± 0.4 4, 3.6 ± 0.24, 1.15 ± 0.28, and 1.3 ± 1.2 ng/100 μg protein, respectively, in TNFR1KO males, WT males, TNFR1KO females, and WT females, respectively, P < 0.002), whereas at 3 days TIMP-1 mRNA fold upregulation compared with type- and sex-matched controls was lowest in WT males (138.32 ± 13.05, 46.74 ± 5.43, 186.09 ± 28.07, and 101.76 ± 22.48, respectively, P < 0.002). MMP-2 and TIMP-2 increased similarly in all infarcted groups. These findings suggest that the benefits of TNFR1 ablation might be attributable at least in part to the attenuation of cytokine-mediated imbalances in MMP-TIMP activity.
Noninvasive ultrasonic measurement of arterial wall motion in mice
Authors: Hartley Craig J. , Reddy Anilkumar K. , Madala Sridhar , Entman Mark L. , Michael Lloyd H. , Taffet George E.
Published: August 2004

Despite the extensive use of genetically altered mice to study cardiovascular physiology and pathology, it remains difficult to quantify arterial function noninvasively in vivo. We have developed a noninvasive Doppler method for quantifying vessel wall motion in anesthetized mice. A 20-MHz probe was held by an alligator clip and positioned over the carotid arteries of 16 mice, including six 3- to 5-mo-old wild-type (WT), four 30-mo-old senescent (old), two apolipoprotein E null (ApoE), and four α-smooth muscle actin null (α-SMA) mice. Doppler signals were obtained simultaneously from both vessel walls and from blood flow. The calculated displacement signals from the near and far walls were subtracted to generate a diameter signal from which the excursion and an augmentation index were calculated. The excursion ranged between 13 μm (in ApoE) and 95 μm (in α-SMA). The augmentation index was lowest in the WT mice (0.06) and highest in the old mice (0.29). We conclude that Doppler signal processing may be used to measure vessel wall motion in mice with high spatial and temporal resolution and that diameter signals can replace pressure signals for calculating the augmentation index. This noninvasive method is able to identify and confirm characteristic changes in arterial properties previously associated with age, atherosclerosis, and the absence of vascular tone.