bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional Overlap but Lack of Complete Cross-Complementation of
Streptococcus mutans
and
Escherichia coli
YidC Orthologs
Authors: Dong Yuxia , Palmer Sara R. , Hasona Adnan , Nagamori Shushi , Kaback H. Ronald , Dalbey Ross E. , Brady L. Jeannine
Published: January 2008

Oxa/YidC/Alb family proteins are chaperones involved in membrane protein insertion and assembly.
Streptococcus mutans
has two YidC paralogs. Elimination of
yidC2
, but not
yidC1
, results in stress sensitivity with decreased membrane-associated F
1
F
o
ATPase activity and an inability to initiate growth at low pH or high salt concentrations (A. Hasona, P. J. Crowley, C. M. Levesque, R. W. Mair, D. G. Cvitkovitch, A. S. Bleiweis, and L. J. Brady, Proc. Natl. Acad. Sci. USA 102:17466-17471, 2005). We now show that
Escherichia coli
YidC complements for acid tolerance, and partially for salt tolerance, in
S. mutans
lacking
yidC2
and that
S. mutans
YidC1 or YidC2 complements growth in liquid medium, restores the proton motive force, and functions to assemble the F
1
F
o
ATPase in a previously engineered
E. coli
YidC depletion strain (J. C. Samuelson, M. Chen, F. Jiang, I. Moller, M. Wiedmann, A. Kuhn, G. J. Phillips, and R. E. Dalbey, Nature 406:637-641, 2000). Both YidC1 and YidC2 also promote membrane insertion of known YidC substrates in
E. coli
; however, complete membrane integrity is not fully replicated, as evidenced by induction of phage shock protein A. While both function to rescue
E. coli
growth in broth, a different result is observed on agar plates: growth of the YidC depletion strain is largely restored by 247YidC2, a hybrid
S. mutans
YidC2 fused to the YidC targeting region, but not by a similar chimera, 247YidC1, nor by YidC1 or YidC2. Simultaneous expression of YidC1 and YidC2 improves complementation on plates. This study demonstrates functional redundancy between YidC orthologs in gram-negative and gram-positive organisms but also highlights differences in their activity depending on growth conditions and species background, suggesting that the complete functional spectrum of each is optimized for the specific bacteria and environment in which they reside.
Mutagenesis of the C1 Oxidation Pathway in
Methanosarcina barkeri
: New Insights into the Mtr/Mer Bypass Pathway
Authors: Welander Paula V. , Metcalf William W.
Published: January 2008

A series of
Methanosarcina barkeri
mutants lacking the genes encoding the enzymes involved in the C1 oxidation/reduction pathway were constructed. Mutants lacking the methyl-tetrahydromethanopterin (H
4
MPT):coenzyme M (CoM) methyltransferase-encoding operon (Δ
mtr
), the methylene-H
4
MPT reductase-encoding gene (Δ
mer
), the methylene-H
4
MPT dehydrogenase-encoding gene (Δ
mtd
), and the formyl-methanofuran:H
4
MPT formyl-transferase-encoding gene (Δ
ftr
) all failed to grow using either methanol or H
2
/CO
2
as a growth substrate, indicating that there is an absolute requirement for the C1 oxidation/reduction pathway for hydrogenotrophic and methylotrophic methanogenesis. The mutants also failed to grow on acetate, and we suggest that this was due to an inability to generate the reducing equivalents needed for biosynthetic reactions. Despite their lack of growth on methanol, the Δ
mtr
and Δ
mer
mutants were capable of producing methane from this substrate, whereas the Δ
mtd
and Δ
ftr
mutants were not. Thus, there is an Mtr/Mer bypass pathway that allows oxidation of methanol to the level of methylene-H
4
MPT in
M. barkeri
. The data further suggested that formaldehyde may be an intermediate in this bypass; however, no methanol dehydrogenase activity was found in Δ
mtr
cell extracts, nor was there an obligate role for the formaldehyde-activating enzyme (Fae), which has been shown to catalyze the condensation of formaldehyde and H
4
MPT in vitro. Both the Δ
mer
and Δ
mtr
mutants were able to grow on a combination of methanol plus acetate, but they did so by metabolic pathways that are clearly distinct from each other and from previously characterized methanogenic pathways.
Functional Characterization of MigA and WapR: Putative Rhamnosyltransferases Involved in Outer Core Oligosaccharide Biosynthesis ofPseudomonas aeruginosa
Authors: Poon Karen K. H. , Westman Erin L. , Vinogradov Evgeny , Jin Shouguang , Lam Joseph S.
Published: January 2008

Pseudomonas aeruginosalipopolysaccharide (LPS) contains two glycoforms of core oligosaccharide (OS); one form is capped with O antigen through an α-1,3-linkedl-rhamnose (l-Rha), while the other is uncapped and contains an α-1,6-linkedl-Rha. Two genes in strain PAO1,wapR(PA5000) andmigA(PA0705), encode putative glycosyltransferases associated with core biosynthesis. We propose that WapR and MigA are the rhamnosyltransferases responsible for the two linkages ofl-Rha to the core. Knockout mutants with mutations in both genes were generated. ThewapRmutant produced LPS lacking O antigen, and addition ofwapRintranscomplemented this defect. ThemigAmutant produced LPS with a truncated outer core and showed no reactivity to outer core-specific monoclonal antibody (MAb) 5C101. Complementation of this mutant withmigArestored reactivity of the LPS to MAb 5C101. Interestingly, LPS from the complementedmigAstrain was not reactive to MAb 18-19 (specific for the core-plus-one O repeat). This was due to overexpression of MigA in the complemented strain that caused an increase in the proportion of the uncapped core OS, thereby decreasing the amount of the core-plus-one O repeat, indicating that MigA has a regulatory role. The structures of LPS from both mutants were elucidated using nuclear magnetic resonance spectroscopy and mass spectrometry. The capped core of thewapRmutant was found to be truncated and lacked α-1,3-l-Rha. In contrast, uncapped core OS from themigAmutant lacked α-1,6-l-Rha. These results provide evidence that WapR is the α-1,3-rhamnosyltransferase, while MigA is the α-1,6-rhamnosyltransferase.
Conjugal Transfer of the
Salmonella enterica
Virulence Plasmid in the Mouse Intestine
Authors: García-Quintanilla Meritxell , Ramos-Morales Francisco , Casadesús Josep
Published: January 2008

BALB/c mice were infected with two
Salmonella enterica
serovar Typhimurium strains, one of which lacked the virulence plasmid. Transconjugants were found at high frequencies in the mouse feces and at low frequencies in the liver and the spleen, suggesting that mating occurred in the gut. Laboratory conditions that mimic those of the small intestine (microaerophilic growth in the presence of 0.3 M NaCl) increased the frequency of virulence plasmid transfer. Sodium deoxycholate, which is found at high concentrations in the duodenum, and sodium propionate, which is abundant in the large intestine, reduced the conjugation frequency. Feces inhibited conjugation. Altogether, these observations suggested that transfer of the virulence plasmid occurred in the distal portion of the small intestine. Conjugation trials in ileal loops provided direct evidence that conjugal transfer of the
Salmonella
virulence plasmid occurs in the ileum in mice.
Identification of the Archaeal
alg7
Gene Homolog (Encoding
N
-Acetylglucosamine-1-Phosphate Transferase) of the N-Linked Glycosylation System by Cross-Domain Complementation in
Saccharomyces cerevisiae
Authors: Shams-Eldin Hosam , Chaban Bonnie , Niehus Sebastian , Schwarz Ralph T. , Jarrell Ken F.
Published: January 2008

The Mv1751 gene product is thought to catalyze the first step in the N-glycosylation pathway in
Methanococcus voltae
. Here, we show that a conditional lethal mutation in the
alg7
gene (
N
-acetylglucosamine-1-phosphate transferase) in
Saccharomyces cerevisiae
was successfully complemented with Mv1751, highlighting a rare case of cross-domain complementation.
Phosphate Acquisition Components of the
Myxococcus xanthus
Pho Regulon Are Regulated by both Phosphate Availability and Development
Authors: Whitworth David E. , Holmes Antony B. , Irvine Alistair G. , Hodgson David A. , Scanlan David J.
Published: January 2008

In many organisms, phosphatase expression and phosphate (P) uptake are coordinately regulated by the Pho regulon. In
Myxococcus xanthus
P limitation initiates multicellular development, a process associated with changes in phosphatase expression. We sought here to characterize the link between P acquisition and development in this bacterium, an organism capable of preying upon other microorganisms as a sole nutrient source.
M. xanthus
seems to possess no significant internal P stores, as reducing the P concentration to less than 10 μM retarded growth within one doubling time. Pyrophosphate, polyphosphate, and glyceraldehyde-3-phosphate could support growth as sole P sources, although many other P-containing biomolecules could not (including nucleic acids and phospholipids). Several Pho regulon promoters were found to be highly active during vegetative growth, and P limitation specifically induced
pstSCAB
, AcPA1, and
pho3
promoter activity and repressed
pit
expression. Enhanced
pstSCAB
and
pho3
promoter activities in a
phoP4
mutant (in the presence of high and low concentrations of P) suggested that PhoP4 acts as a repressor of these genes. However, in a
phoP4
background, the activities of
pstSCAB
remained P regulated, suggesting that there is additional regulation by a P-sensitive factor. Initiation of multicellular development caused immediate down-regulation of Pho regulon genes and caused
pstSCAB
and
pho3
promoter activities to become P insensitive. Hence, P acquisition components of the
M. xanthus
Pho regulon are regulated by both P availability and development, with developmental down-regulation overriding up-regulation by P limitation. These observations suggest that when development is initiated, subsequent changes in P availability become irrelevant to the population, which presumably has sufficient intrinsic P to ensure completion of the developmental program.
Physiological Effects of Anti-TRAP Protein Activity and tRNA
Trp
Charging on
trp
Operon Expression in
Bacillus subtilis
Authors: Cruz-Vera Luis R. , Gong Ming , Yanofsky Charles
Published: January 2008

The
Bacillus subtilis
anti-TRAP protein regulates the ability of the tryptophan-activated TRAP protein to bind to
trp
operon leader RNA and promote transcription termination. AT synthesis is regulated both transcriptionally and translationally by uncharged tRNA
Trp
. In this study, we examined the roles of AT synthesis and tRNA
Trp
charging in mediating physiological responses to tryptophan starvation. Adding excess phenylalanine to wild-type cultures reduced the charged tRNA
Trp
level from 80% to 40%; the charged level decreased further, to 25%, in an AT-deficient mutant. Adding tryptophan with phenylalanine increased the charged tRNA
Trp
level, implying that phenylalanine, when added alone, reduces the availability of tryptophan for tRNA
Trp
charging. Changes in the charged tRNA
Trp
level observed during growth with added phenylalanine were associated with increased transcription of the genes of tryptophan metabolism. Nutritional shift experiments, from a medium containing tryptophan to a medium with phenylalanine and tyrosine, showed that wild-type cultures gradually reduced their charged tRNA
Trp
level. When this shift was performed with an AT-deficient mutant, the charged tRNA
Trp
level decreased even further. Growth rates for wild-type and mutant strains deficient in AT or TRAP or that overproduce AT were compared in various media. A lack of TRAP or overproduction of AT resulted in phenylalanine being required for growth. These findings reveal the importance of AT in maintaining a balance between the synthesis of tryptophan versus the synthesis of phenylalanine, with the level of charged tRNA
Trp
acting as the crucial signal regulating AT production.
Hypertension in noise-exposed sawmill workers: a cohort study
Authors: Sbihi H , Davies H W , Demers P A
Published: January 2008

Objective:

To investigate the hypothesised association between exposure to high levels of noise and risk of hypertension using quantitative exposure assessment and administrative health data.

Methods:

This study followed a cohort of 10 872 sawmill workers in British Columbia from 1991 to 1998. Subjects were linked with provincial hospital discharge, outpatient and vital status databases. Cases were males who died, had at least one hospital admission, or who had three doctor visits within 70 days, for hypertension (ICD-9 codes 401–405). We used four exposure metrics: cumulative exposure, and duration of exposure above thresholds of 85 dBA, 90 dBA and 95 dBA. Relative risks were estimated using Poisson regression with the low-exposure group as controls and adjusting for age, ethnicity and calendar period.

Results:

828 cases were identified. The results showed a monotonic increase in hypertension incidence with cumulative exposure. The risk in the highest exposed population was 32% higher than baseline. Similar results were found using duration of exposure metrics. The highest relative risk was 1.5 in workers exposed for more than 30 years at 85 dBA. Exposure-response trends were statistically significant.

Conclusions:

The risk of hypertension was positively associated with noise exposure above 85 dB.
How do experiences in Iraq affect alcohol use among male UK armed forces personnel?
Authors: Browne T , Iversen A , Hull L , Workman L , Barker C , Horn O , Jones M , Murphy D , Greenberg N , Rona R , Hotopf M , Wessely S , Fear N T
Published: January 2008

Objectives:

This paper reports on a statistically significant association between alcohol use and deployment to the 2003 Iraq War. It assesses the occupational factors and deployment experiences associated with heavy drinking in regular UK servicemen deployed to Iraq in the first phase of the 2003 Iraq War (Operation TELIC 1, the military codename for the conflict in Iraq).

Methods:

A random representative sample of 3578 regular male UK Armed Forces personnel who were deployed to Iraq during Operation TELIC 1 participated in a cross-sectional postal questionnaire study (response rate 61%). Participants completed a questionnaire, between June 2004 and March 2006 (ie, after deployment), about their health, including a measure of alcohol use (Alcohol Use Disorders Identification Test, AUDIT) and questions about their experiences on deployment to Iraq. Heavy drinkers were identified as those scoring 16 or above on the AUDIT.

Results:

After adjustment for sociodemographic and military factors, and the presence of psychological distress, heavy drinkers were more likely to have had major problems at home during (odds ratio (OR) 1.33, 95% confidence interval (CI) 1.04 to 1.70) and following their deployment (OR 1.68, 95% CI 1.32 to 2.14). Being deployed with their parent unit (OR 1.28, 95% CI 1.02 to 1.61), medium to high in-theatre unit comradeship (medium: OR 1.35, 95% CI 1.04 to 1.77; high: OR 1.35, 95% CI 1.02 to 1.79) and poor unit leadership (OR 1.78, 95% CI 1.37 to 2.31) were also associated with heavy drinking.

Conclusions:

Deployment experiences and problems at home during and following deployment, as well as the occupational milieu of the unit, influence personnel’s risk of heavy drinking.
Blood markers of inflammation and coagulation and exposure to airborne particles in employees in the Stockholm underground
Authors: Bigert C , Alderling M , Svartengren M , Plato N , de Faire U , Gustavsson P
Published: January 2008

Objectives:

Although associations have been found between levels of ambient airborne particles and cardiovascular disease (CVD) in the general population, little is known about possible cardiovascular effects from high exposure to particles in underground railway systems. This study investigates risk markers for CVD in employees exposed to particles in the Stockholm underground system.

Methods:

79 workers (54 men and 25 women) in the Stockholm underground were investigated between November 2004 and March 2005. All were non-smokers aged 25–50 years. Three exposure groups were delineated: 29 platform workers with high exposure to particles, 29 train drivers with medium exposure and 21 ticket sellers with low exposure (control group). A baseline blood sample was taken after 2 non-working days, and a second sample after 2 working days, for analysis of levels of plasminogen activator inhibitor-1 (PAI-1), high-sensitivity C-reactive protein (hs-CRP), interleukin-6, fibrinogen, von Willebrand factor and factor VII. The study investigated changes in plasma concentrations between sample 1 and sample 2, and differences in average concentrations between the groups.

Results:

No changes between sample 1 and 2 were found that could be attributed to particle exposure. However, the highly exposed platform workers were found to have higher plasma concentrations of PAI-1 and hs-CRP than the ticket sellers and train drivers. This suggests that particle exposure could have a long-term inflammatory effect. These differences remained for PAI-1 in the comparison between platform workers and ticket sellers after adjusting for body mass index.

Conclusions:

Employees who were highly exposed to airborne particles in the Stockholm underground tended to have elevated levels of risk markers for CVD relative to employees with low exposure. However, the differences observed cannot definitely be linked to particle exposure as such.
STATUS OF |Vub|, |Vcb| AND THEIR RELATIVE PHASE
Authors: KOWALEWSKI R. V.
Published: January 2008

The current status of the determinations of the CKM elements Vub, and Vcb is reviewed and future prospects are discussed.
Faster XML data validation in a programming language with XML datatypes
Authors: Svensson Kurt
Published: January 2008

EDI-C is a programming language used in B2B (EDI, WebServices) applications. It is possible to declare XML variables in the language. XML variables are declared in a way similar to structures in C and C++. These variables are accessed through dot-notation. Validation information (facets) can also be declared. The XML structures and their validation values are, at compile time, optimized for fast evaluation and execution in the runtime environment. Usually XSD schema are read and evaluated when an XML document loads -- our method loads and evaluates the XSD schema at compile time. Thus, when executing a program, the XSD schema has already been loaded and evaluated -- i.e., it's no longer necessary to load and evaluate each time the program is executed. This method increases XML processing speed, which is vital for WebServices messaging.
Georg Gottlob speaks out
Authors: Winslett Marianne
Published: January 2008

Welcome to this installment of ACM SIGMOD Record's series of interviews with distinguished members of the database community. I'm Marianne Winslett, and today we are at the SIGMOD 2006 conference in Chicago, Illinois. I have here with me Georg Gottlob, who is a professor of computing science at Oxford University. Before that he was a professor at the Technical University of Vienna for many years. His research interests lie in database theory, logic, AI, and complexity. Georg is a co-founder of Lixto Corporation, and until recently he was the editor in chief of
AI Communications
. Georg's PhD is from the Technical University of Vienna. So, Georg, welcome!
Effects of nonselective endothelin-1 receptor antagonism on cardiac mast cell-mediated ventricular remodeling in rats
Authors: Murray David B. , Gardner Jason D. , Brower Gregory L. , Janicki Joseph S.
Published: January 2008

The objective of this study was to investigate the effect a nonselective endothelin-1 (ET-1) receptor antagonist (bosentan) had on the acute myocardial remodeling process including left ventricular (LV) mast cells and matrix metalloproteinase (MMP) activity secondary to volume overload. Additionally, we investigated the overall functional outcome of preventative endothelin receptor antagonism during 14 days of chronic volume overload. LV tissue from sham-operated (Sham), untreated-fistula (Fist), and bosentan (100 mg·kg−1·day−1)-treated animals (Fist + Bos) was analyzed for mast cell density, MMP activity, and myocardial collagen volume fraction at 1 and 5 days after the creation of an aortocaval fistula. When compared with untreated fistulas, bosentan treatment prevented the marked increase in LV mast cell density at 1 day postfistula (3.1 ± 0.3 vs. 1.3 ± 0.3 LV mast cells/mm2, Fist vs. Fist + Bos, P ≤ 0.01). Additionally, the substantial increase in MMP-2 activation in the untreated fistula at 1 day was prevented following bosentan treatment (1.6 ± 0.3 vs. 0.9 ± 0.1 arbitrary activity units, Fist vs. Fist + Bos, P ≤ 0.01). The marked decrease in collagen volume fraction seen in the Fist group (1.4 ± 0.1 vs. 0.8 ± 0.1% myocardial tissue, Sham vs. Fist, P ≤ 0.01) was significantly attenuated following bosentan treatment at both the 1- and 5-day time points. Lastly, a 2-wk preventative treatment with bosentan resulted in significant attenuation of the increase in LV end-systolic and -diastolic volumes compared with those in untreated fistula hearts. In summary, nonselective ET-1 antagonism prevents the acute increases in cardiac mast cell density and MMP activation induced secondary to chronic volume overload. By preventing these events, ET-1 antagonism was efficacious in attenuating ventricular dilatation and limiting the development of structural and functional deficits in the first 2 wk of chronic volume overload. Accordingly, these results are the first to demonstrate that cardiac mast cells are responsive to the endogenous endothelin system in vivo. Another novel finding from this study is that chronic nonspecific endothelin antagonism may inadvertently potentiate ET-1-mediated signaling.
Complement inhibition reduces injury in the type 2 diabetic heart following ischemia and reperfusion
Authors: La Bonte Laura R. , Davis-Gorman Grace , Stahl Gregory L. , McDonagh Paul F.
Published: January 2008

Chronic inflammation exacerbates the cardiovascular complications of diabetes. Complement activation plays an important role in the inflammatory response and is known to be involved in ischemia-reperfusion (I/R) injury in the nondiabetic heart. The purpose of this study was to determine if increased complement deposition explains, in part, the increased severity of neutrophil-mediated I/R injury in the type 2 diabetic heart. Nondiabetic Zucker lean control (ZLC) and Zucker diabetic fatty (ZDF) rats underwent 30 min of coronary artery occlusion followed by 120 min of reperfusion. Another group of ZDF rats was treated with the complement inhibitor FUT-175 before reperfusion. Left ventricular (LV) tissue samples were stained for complement deposition and neutrophil accumulation following reperfusion. We found significantly more complement deposition in the ZDF LV compared with the ZLC ( P < 0.05), and complement deposition was associated with significantly greater neutrophil accumulation. In whole blood samples taken preischemia and at 120 min reperfusion, neutrophils exhibited significantly more CD11b expression in the ZDF group compared with the ZLC group ( P < 0.05). Furthermore, intracellular adhesion molecule (ICAM)-1 expression following I/R was increased significantly in ZDF hearts compared with ZLC hearts ( P < 0.001). These results indicate that, in the ZDF heart, increased ICAM-1 and polymorphonuclear neutrophil (PMN) CD11b expression play a role in increasing PMN accumulation following I/R. The infarct size of the ZDF was significantly greater than ZLC ( P < 0.05), and treatment with FUT-175 significantly decreased infarct size, complement deposition, and PMN accumulation in the diabetic heart. These findings indicate an exacerbated inflammatory response in the type 2 diabetic heart that contributes to the increased tissue injury observed following ischemia and reperfusion.
Heme oxygenase-1 induction depletes heme and attenuates pulmonary artery relaxation and guanylate cyclase activation by nitric oxide
Authors: Mingone Christopher J. , Ahmad Mansoor , Gupte Sachin A. , Chow Joseph L. , Wolin Michael S.
Published: January 2008

This study examines in endothelium-denuded bovine pulmonary arteries the effects of increasing heme oxygenase-1 (HO-1) activity on relaxation and soluble guanylate cyclase (sGC) activation by nitric oxide (NO). A 24-h organ culture with 0.1 mM cobalt chloride (CoCl2) or 30 μM Co-protoporphyrin IX was developed as a method of increasing HO-1 expression. These treatments increased HO-1 expression and HO activity by approximately two- to fourfold and lowered heme levels by 40–45%. Induction of HO-1 was associated with an attenuation of pulmonary arterial relaxation to the NO-donor spermine-NONOate. The presence of a HO-1 inhibitor 30 μM chromium mesoporphyrin during the 24-h organ culture (but not acute treatment with this agent) reversed the attenuation of relaxation to NO seen in arteries co-cultured with agents that increased HO-1. Relaxation to isoproterenol, which is thought to be mediated through cAMP, was not altered in arteries with increased HO-1. Inducers of HO-1 did not appear to alter basal sGC activity in arterial homogenates or expression of the β1-subunit of sGC. However, the increase in activity seen in the presence of 1 μM spermine-NONOate was attenuated in homogenates obtained from arteries with increased HO-1. Since arteries with increased HO-1 had decreased levels of superoxide detected by the chemiluminescence of 5 μM lucigenin, superoxide did not appear to be mediating the attenuation of relaxation to NO. These data suggest that increasing HO-1 activity depletes heme, and this is associated with an attenuation of pulmonary artery relaxation and sGC activation responses to NO.
Experimental studies of atrial fibrillation: a comparison of two pacing models
Authors: Laurent Gabriel , Moe Gordon , Hu Xudong , Leong-Poi Howard , Connelly Kim A. , So Petsy Pui-Sze , Ramadeen Andrew , Doumanovskaia Liia , Konig Andrea , Trogadis Judy , Courtman David , Strauss Bradley , Dorian Paul
Published: January 2008

Rapid ventricular pacing (RVP) is a well-established animal model of atrial fibrillation (AF). However, this model is limited by a high mortality rate and severe heart failure. The purpose of our study was to assess a new canine model of inducible AF. We performed acute, short-term, simultaneous atrioventricular pacing (SAVP) and RVP (in random order) in 14 dogs for 30 s. SAVP produced more echocardiographic pulmonary venous flow reversal, a greater increase in mean pulmonary capillary wedge pressure, and a significantly greater decrease in left atrial emptying function (−84.4 ± 38.6% vs. −23.7 ± 27.1%, P < 0.05) than RVP. Thirty dogs were randomized to three, longer-term, study groups: eight dogs in the control group (no pacing), eight dogs in the RVP group (2 wk at 240 beats/min followed by 3 wk at 220 beats/min), and fourteen dogs in the SAVP group (2 wk at 220 beats/min). SAVP induced less left ventricular dysfunction but more left atrial dysfunction than RVP. SAVP dogs had similar atrial effective refractory periods as RVP dogs but more heterogeneity in conduction and more AF inducibility (83% vs. 40%, P < 0.05) and maintenance (median 1,660 vs. 710 s, P < 0.05) than RVP dogs. SAVP induced more collagen turnover and was associated with a significantly greater increase in type III collagen in the atria compared with RVP dogs (6.9 ± 1.5 vs. 4.8 ± 1.6, respectively, P < 0.05 vs. 1.1 ± 0.7 in unpaced control dogs). In conclusion, the SAVP model induced profound mechanical and substrate atrial remodeling and reproducible sustained AF. This new model is clinically relevant and may be useful for testing AF interventions.
Effect of dietary sodium on vasoconstriction and eNOS-mediated vascular relaxation in caveolin-1-deficient mice
Authors: Pojoga Luminita H. , Yao Tham M. , Sinha Sumi , Ross Reagan L. , Lin Jeffery C. , Raffetto Joseph D. , Adler Gail K. , Williams Gordon H. , Khalil Raouf A.
Published: January 2008

Changes in dietary sodium intake are associated with changes in vascular volume and reactivity that may be mediated, in part, by alterations in endothelial nitric oxide synthase (eNOS) activity. Caveolin-1 (Cav-1), a transmembrane anchoring protein in the plasma membrane caveolae, binds eNOS and limits its translocation and activation. To test the hypothesis that endothelial Cav-1 participates in the dietary sodium-mediated effects on vascular function, we assessed vascular responses and nitric oxide (NO)-mediated mechanisms of vascular relaxation in Cav-1 knockout mice (Cav-1−/−) and wild-type control mice (WT; Cav-1+/+) placed on a high-salt (HS; 4% NaCl) or low-salt (LS; 0.08% NaCl) diet for 16 days. After the systolic blood pressure was measured, the thoracic aorta was isolated for measurement of vascular reactivity and NO production, and the heart was used for measurement of eNOS expression and/or activity. The blood pressure was elevated in HS mice treated with NG-nitro-l-arginine methyl ester and more so in Cav-1−/−than WT mice and was significantly reduced during the LS diet. Phenylephrine caused vascular contraction that was significantly reduced in Cav-1−/−(maximum 0.25 ± 0.06 g/mg) compared with WT (0.75 ± 0.22 g/mg) on the HS diet, and the differences were eliminated with the LS diet. Also, vascular contraction in response to membrane depolarization by high KCl (96 mM) was reduced in Cav-1−/−(0.27 ± 0.05 g/mg) compared with WT mice (0.53 ± 0.12 g/mg) on the HS diet, suggesting that the reduced vascular contraction is not limited to a particular receptor. Acetylcholine (10−5M) caused aortic relaxation in WT mice on HS (23.6 ± 3.5%) and LS (23.7 ± 5.5%) that was enhanced in Cav-1−/−HS (72.6 ± 6.1%) and more so in Cav-1−/−LS mice (93.6 ± 3.5%). RT-PCR analysis indicated increased eNOS mRNA expression in the aorta and heart, and Western blots indicated increased total eNOS and phosphorylated eNOS in the heart of Cav-1−/−compared with WT mice on the HS diet, and the genotypic differences were less apparent during the LS diet. Thus Cav-1 deficiency during the HS diet is associated with decreased vasoconstriction, increased vascular relaxation, and increased eNOS expression and activity, and these effects are altered during the LS diet. The data support the hypothesis that endothelial Cav-1, likely through an effect on eNOS activity, plays a prominent role in the regulation of vascular function during substantial changes in dietary sodium intake.
Role of quercetin in modulating rat cardiomyocyte gene expression profile
Authors: Angeloni C. , Leoncini E. , Malaguti M. , Angelini S. , Hrelia P. , Hrelia S.
Published: January 2008

Despite extensive studies, the fundamental mechanisms responsible for the development and progression of cardiovascular diseases have not yet been fully elucidated. Recent experimental and clinical studies have suggested that reactive oxygen species play a major pathological role. Oxidative stress reduction induced by flavonoids has been regarded by many as the most likely mechanism in the protective effects of these compounds; however, there is an emerging view that flavonoids may also exert modulatory actions on protein kinase and lipid kinase signaling pathways. Quercetin, a major flavonoid present in the human diet, has been widely studied, and its biological properties are consistent with its protective role in the cardiovascular system. However, it remains unknown whether the cardioprotective effects of quercetin may also occur through the modulation of genes involved in cell survival. The main goal of this study was to examine the gene expression profiling of cultured rat primary cardiomyocytes treated with quercetin using DNA microarrays and to relate these data to functional effects. Results showed distinct temporal changes in gene expression induced by quercetin and a strong upregulation of phase 2 enzymes, highlighting quercetin ability to act also with an indirect antioxidant mechanism.
CB2cannabinoid receptor agonist JWH-015 modulates human monocyte migration through defined intracellular signaling pathways
Authors: Montecucco Fabrizio , Burger Fabienne , Mach François , Steffens Sabine
Published: January 2008

Recruitment of leukocytes to inflammatory sites is crucial in the pathogenesis of chronic inflammatory diseases. The aim of this study was to investigate if activation of CB2cannabinoid receptors would modulate the chemotactic response of human monocytes. Human monocytes treated with the CB2agonist JWH-015 for 12–18 h showed significantly reduced migration to chemokines CCL2 and CCL3, associated with reduced mRNA and surface expression of their receptors CCR2 and CCR1. The induction of ICAM-1 in response to IFN-γ was inhibited by JWH-015. Moreover, JWH-015 cross-desensitized human monocytes for migration in response to CCL2 and CCL3 by its own chemoattractant properties. The CB2-selective antagonist SR-144528, but not the CB1antagonist SR-147778, reversed JWH-015-induced actions, whereas the CB2agonist JWH-133 mimicked the effects of JWH-015. The investigation of underlying pathways revealed the involvement of phosphatidylinositol 3-kinase/Akt and ERK1/2 but not p38 MAPK. In conclusion, selective activation of CB2receptors modulates chemotaxis of human monocytes, which might have crucial effects in chronic inflammatory disorders such as atherosclerosis or rheumatoid arthritis.
Regulation of store-operated Ca2+entry by CD38 in human airway smooth muscle
Authors: Sieck Gary C. , White Thomas A. , Thompson Michael A. , Pabelick Christina M. , Wylam Mark E. , Prakash Y. S.
Published: January 2008

The ectoenzyme CD38 catalyzes synthesis and degradation of cyclic ADP ribose in airway smooth muscle (ASM). The proinflammatory cytokine TNFα, which enhances agonist-induced intracellular Ca2+([Ca2+]i) responses, has been previously shown to increases CD38 expression. In the present study, we tested the hypothesis that the effects of TNFα on CD38 expression vs. changes in [Ca2+]iregulation in ASM cells are linked. Using isolated human ASM cells, CD38 expression was either increased (transfection) or knocked down [small interfering RNA (siRNA)], and [Ca2+]iresponses to sarcoplasmic reticulum depletion [i.e., store-operated Ca2+entry (SOCE)] were evaluated in the presence vs. absence of TNFα. Results confirmed that TNFα significantly increased CD38 expression and ADP-ribosyl cyclase activity, an effect inhibited by CD38 siRNA, but unaltered by CD38 overexpression. CD38 suppression blunted, whereas overexpression enhanced, ACh-induced [Ca2+]iresponses. TNFα-induced enhancement of [Ca2+]iresponse to agonist was blunted by CD38 suppression, but enhanced by CD38 overexpression. Finally, TNFα-induced increase in SOCE was blunted by CD38 siRNA and potentiated by CD38 overexpression. Overall, these results indicate a critical role for CD38 in TNFα-induced enhancement of [Ca2+]iin human ASM cells, and potentially to TNFα augmentation of airway responsiveness.
Nix-Mediated Apoptosis Links Myocardial Fibrosis, Cardiac Remodeling, and Hypertrophy Decompensation
Authors: Diwan Abhinav , Wansapura Janaka , Syed Faisal M. , Matkovich Scot J. , Lorenz John N. , Dorn Gerald W.
Published: January 2008

Background—

Pathological cardiac hypertrophy inevitably remodels, leading to functional decompensation. Although modulation of apoptosis-regulating genes occurs in cardiac hypertrophy, a causal role for programmed cardiomyocyte death in left ventricular (LV) remodeling has not been established.

Methods and Results—

We targeted the gene for proapoptotic Nix, which is transcriptionally upregulated in pressure overload and Gq-dependent hypertrophies, in the mouse germ line or specifically in cardiomyocytes (knockout [KO]) and conditionally overexpressed it in the heart (transgenic [TG]). Conditional forced Nix expression acted synergistically with the prohypertrophic Gq transgene to increase cardiomyocyte apoptosis (0.8±0.1% in GqTG versus 7.8±0.6% in GqTG+NixTG;
P
<0.001), causing lethal cardiomyopathy with LV dilation and depressed systolic function (percent fractional shortening, 39±4 versus 23±4;
P
=0.042). In the reciprocal experiment, germ-line
Nix
ablation significantly reduced cardiomyocyte apoptosis (4.8±0.2% in GqTG+
Nix
KO versus 8.4±0.5% in GqTG;
P
=0.001), which improved percent fractional shortening (43±3% versus 27±3%;
P
=0.017), attenuated LV remodeling, and largely prevented lethality in the Gq peripartum model of apoptotic cardiomyopathy. Cardiac-specific (Nkx2.5-Cre)
Nix
KO mice subjected to transverse aortic constriction developed significantly less LV dilation by echocardiography and magnetic resonance imaging, maintained concentric remodeling, and exhibited preserved LV ejection fraction (61±2% in transverse aortic constriction cardiac
Nix
KO versus 36±6% in transverse aortic constriction wild-type mice;
P
=0.003) at 9 weeks, with reduced cardiomyocyte apoptosis at day 4 (1.70±0.21% versus 2.73±0.35%;
P
=0.032).

Conclusions—

Nix-induced cardiomyocyte apoptosis is a major determinant of adverse remodeling in pathological hypertrophies, a finding that suggests therapeutic value for apoptosis inhibition to prevent cardiomyopathic decompensation.
Tropospheric Adjustment Induces a Cloud Component in CO2 Forcing
Authors: Gregory Jonathan , Webb Mark
Published: January 2008

The radiative forcing of CO2 and the climate feedback parameter are evaluated in several climate models with slab oceans by regressing the annual-mean global-mean top-of-atmosphere radiative flux against the annual-mean global-mean surface air temperature change ΔT following a doubling of atmospheric CO2 concentration. The method indicates that in many models there is a significant rapid tropospheric adjustment to CO2 leading to changes in cloud, and reducing the effective radiative forcing, in a way analogous to the indirect and semidirect effects of aerosol. By contrast, in most models the cloud feedback is small, defined as the part of the change that evolves with ΔT. Comparison with forcing evaluated by fixing sea surface conditions gives qualitatively similar results for the cloud components of forcing, both globally and locally. Tropospheric adjustment to CO2 may be responsible for some of the model spread in equilibrium climate sensitivity and could affect time-dependent climate projections.
Relationships Among Private Speech and Creativity in Head Start and Low—Socioeconomic Status Preschool Children
Authors: Daugherty Martha , White C. Stephen
Published: January 2008

The purpose of this study was to explore Vygotsky's notion of private speech as a cognitive self-regulatory process and how it related to creativity measures among at-risk children. Thirty-two Head Start and state-funded Pre-K children completed the Torrance creativity test Thinking Creatively in Action and Movement (TCAM). The children's private speech was collected in an open play context and while children completed structured logical— mathematical activities. Results revealed that both originality and fluency creativity were related to self-direction private speech and grand total private speech. Findings support that cognitive self-regulating private speech may be related to creative thinking and that private speech may offer a method for assessing early creative thinking in children from various cultural and economic backgrounds.
Reviving Perry: An Analysis of Epistemological Change by Gender and Ethnicity Among Gifted High School Students
Authors: Thomas Jerald A.
Published: January 2008

This study examines development along Perry's intellectual and ethical scale among three successive graduating classes of students identified as gifted and talented in mathematics and science. Perry posits that intellectual development proceeds from a basic dualism through nine stages (“positions”) and culminates with a sense of personal identify and commitment. Perry suggests that the college years act as the agent of intellectual development, but others have argued that Perry's scheme is not flexible enough to account for gender- and culture-based differences. This study uses a paper-and-pencil questionnaire to describe developmental characteristics of gifted high school students and examines between-group differences between gender and ethnic groups at the high school sophomore and senior years. All groups showed significant improvement from sophomore to senior year. There were no differences by gender or ethnicity at the sophomore year, but by senior year, significant developmental differences existed among ethnic groups.
Africana Studies and Economics
Authors: Stewart James B.
Published: January 2008

The scope and meaning of terms like African American Studies, Black Studies, and Africana Studies have evolved continually since the field was established in schools, colleges, and universities in the late 1960s. Discourse about the economic conditions of people of African descent has always constituted an important dimension of the Black intellectual tradition that Africana Studies seeks to preserve and extend. Significant barriers exist, however, to collaboration between economists and Africana Studies specialists. Opportunities to collaborate across the disciplines arise in addressing issues such as hyper-unemployment, pervasive poverty, environmental racism, Black land loss, and the plight of Black farmers. The author suggests that efforts by Africana Studies specialists to understand many of the current dynamics could be enhanced through collaboration with those economists attempting to develop the subfield of stratification economics.
Rheology, Morphology, and Mechanical and Thermal Properties of Blends of Propylene Based Plastomer and Ethylene/1-Octene Copolymer
Authors: Guo Wen-Yu , Bo Peng
Published: January 2008

Blends of propylene based plastomer (DP) and ethylene/1-octene copolymer (EOC) of various concentrations are prepared by a melt-blending process at 160°C, using a corotating twin-screw extruder. The rheology, phase morphology, and mechanical and thermal properties of DP/EOC blends are investigated. The results show that addition of DP in EOC can lead to significant improvement of mechanical properties, including yield strength, strength at break, and Young's modulus, concomitant with the reduction of melt viscosity. The experimental data for melt viscosity and elongation at break respectively display a positive deviation from additivity, indicating the enhancement of the component interaction and superior interface properties between DP and EOC phases. The transition from plastic to elastomeric properties coincides with phase inversion. At this 85/15 DP/EOC composition, the decrease in the viscosity of DP matrix enhances EOC dispersed phase size, due to the increase in their viscosity mismatch. DSC analysis shows that the melting temperature of DP and EOC phases in blends remains constant irrespective of the composition, respectively. The nucleation effect of EOC on DP tends to increase the crystallization temperature of DP phase. It is also verified that the EOC phase can be prevented from crystallizing with increasing DP content in the blends.
Alternative Politics and the Transformation of Society–Military Relations
Authors: Levy Yagil , Mizrahi Shlomo
Published: January 2008

This article attempts to explain transformations in military—society relations using models developed in the context of political participation and social learning. The authors suggest that patterns of alternative politics might evolve from the undermining of the “republican contract,” that is, the exchange between citizens' military sacrifice and the rights and rewards granted to them by the state. This situation creates growing dissatisfaction among citizens that may trigger collective action, even among soldiers. Barriers to internal bargaining within the military generate modes of alternative politics in the military—society realm. Drawing from the case of Israel, the authors illustrate these strategies by focusing on conscientious objection, “gray refusal,” reservists' rebellions, and a direct form of civilian monitoring of the army.
The Scholarship of Elegance and Significance
Authors: Evans Karen G. , Lowery Daniel
Published: January 2008

In this article, the authors examine the importance of expressive and aesthetic truth claims to public administration scholars, and present a model to aid them in making and evaluating such claims. Sincere expression adds credibility to an argument, and quality of expression can lend elegance to a truth claim. Expressive or aesthetic truth claims are not merely used to heighten emotions or enhance sensory experience; more importantly, they can also contribute to the efficacy of an empirical or normative truth claim. Through the judicious use of these truth claims, significance and meaning can be attached to the bare facts of empirical inquiry or a recommendation to act.
Differential Parenting Between Mothers and Fathers
Authors: McKinney Cliff , Renk Kimberly
Published: January 2008

Although the relationship between parenting and outcomes for children and adolescents has been examined, differences between maternal and paternal parenting styles have received less attention, particularly in the case of late adolescents. As a result, this article examines the relationship between late adolescents' perceptions of their mothers' and fathers' parenting styles and their own emotional adjustment. Findings of this study suggest that mothers and fathers use different parenting styles for their sons and daughters. It also suggests that different combinations of maternal and paternal parenting (e.g., a permissive father parenting with an authoritarian mother) are related to late adolescents' emotional adjustment, with late adolescents who have at least one authoritative parent showing better adjustment than those who do not have such a parent. Overall, this study emphasizes the importance of examining dyadic parent—adolescent relationships, and it suggests that having one authoritative parent may be a protective factor for late adolescents.
Family Structure History and Adolescent Adjustment
Authors: Cavanagh Shannon E.
Published: January 2008

As patterns of union formation and dissolution in adult lives become complex, the living arrangements of American children are becoming increasingly fluid. With a sample ( N = 12,843) drawn from the National Longitudinal Study of Adolescent Health, this study attempted to capture this complexity by mapping out children's family structure histories across their early life course, investigating the implications of these arrangements for their general adjustment, and finally, identifying family processes that explained these associations. The findings suggest that a sizable minority of young people experience dynamic family structure arrangements. Moreover, family structure at adolescence best predicted later emotional distress, and family structure at adolescence plus an indicator of cumulative family instability across childhood best predicted current marijuana use. More so than indicators tapping social control, levels of family connectedness and parent—adolescent relationship quality were key conduits for these associations.
The Media Sports Cultural Complex
Authors: Scherer Jay , Falcous Mark , Jackson Steven J.
Published: January 2008

This article explores the interdependence of interest groups operating within the media sports cultural complex in relation to the national sport of rugby union in New Zealand/Aotearoa. Specifically, we scrutinize the corporate “partnerships” between the New Zealand Rugby Union (NZRU), Adidas, and News Corporation in relation to issues and debates surrounding the globalization of New Zealand's iconic rugby team, the All Blacks. The article draws on extensive interviews with the NZRU's marketing and sponsorship manager and Adidas New Zealand's marketing manager. These interviews provide rare insights into how the strategies of these organizations, and their interrelated (but not interchangeable) commercial objectives, set limits and exert powerful pressures on aspects of the production and consumption of the national sporting mythology in New Zealand.