bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Affecting Variability in Time between Addition of Nutrient Germinants and Rapid Dipicolinic Acid Release during Germination of Spores of
Bacillus
Species
Authors: Zhang Pengfei , Garner Will , Yi Xuan , Yu Ji , Li Yong-qing , Setlow Peter
Published: May 2010

The simultaneous nutrient germination of hundreds of individual wild-type spores of three
Bacillus
species and a number of
Bacillus subtilis
strains has been measured by two new methods, and rates of release of the great majority of the large pool of dipicolinic acid (DPA) from individual spores of
B. subtilis
strains has been measured by Raman spectroscopy with laser tweezers. The results from these analyses and published data have allowed a number of significant conclusions about the germination of spores of
Bacillus
species as follows. (i) The time needed for release of the great majority of a
Bacillus
spore's DPA once rapid DPA release had begun (Δ
T
release
) during nutrient germination was independent of the concentration of nutrient germinant used, the level of the germinant receptors (GRs) that recognize nutrient germinants used and heat activation prior to germination. Values for Δ
T
release
were generally 0.5 to 3 min at 25 to 37°C for individual wild-type spores. (ii) Despite the conclusion above, germination of individual spores in populations was very heterogeneous, with some spores in wild-type populations completing germination ≥15-fold slower than others. (iii) The major factor in the heterogeneity in germination of individual spores in populations was the highly variable lag time,
T
lag
, between mixing spores with nutrient germinants and the beginning of Δ
T
release
. (iv) A number of factors decrease spores'
T
lag
values including heat activation, increased levels of GRs/spore, and higher levels of nutrient germinants. These latter factors appear to affect the level of activated GRs/spore during nutrient germination. (v) The conclusions above lead to the simple prediction that a major factor causing heterogeneity in
Bacillus
spore germination is the number of functional GRs in individual spores, a number that presumably varies significantly between spores in populations.
Complete Genome Sequence of the Aerobic Facultative Methanotroph
Methylocella silvestris
BL2
Authors: Chen Yin , Crombie Andrew , Rahman M. Tanvir , Dedysh Svetlana N. , Liesack Werner , Stott Matthew B. , Alam Maqsudul , Theisen Andreas R. , Murrell J. Colin , Dunfield Peter F.
Published: May 2010

Methylocella silvestris
BL2 is an aerobic methanotroph originally isolated from an acidic forest soil in Germany. It is the first fully authenticated facultative methanotroph. It grows not only on methane and other one-carbon (C
1
) substrates, but also on some compounds containing carbon-carbon bonds, such as acetate, pyruvate, propane, and succinate. Here we report the full genome sequence of this bacterium.
Genome Sequence of the Novel Marine Member of the
Gammaproteobacteria
Strain HTCC5015
Authors: Thrash J. Cameron , Stingl Ulrich , Cho Jang-Cheon , Ferriera Steve , Johnson Justin , Vergin Kevin L. , Giovannoni Stephen J.
Published: May 2010

HTCC5015 is a novel, highly divergent marine member of the
Gammaproteobacteria
, currently without a cultured representative with greater than 89% 16S rRNA gene identity to itself. The organism was isolated from water collected from Hydrostation S south of Bermuda using high-throughput dilution-to-extinction culturing techniques. Here we present the genome sequence of the unique
Gammaproteobacterium
strain HTCC5015.
Genome Sequences of Strains HTCC2148 and HTCC2080, Belonging to the OM60/NOR5 Clade of the
Gammaproteobacteria
Authors: Thrash J. Cameron , Cho Jang-Cheon , Ferriera Steve , Johnson Justin , Vergin Kevin L. , Giovannoni Stephen J.
Published: May 2010

Organisms in the OM60/NOR5 clade of the
Gammaproteobacteria
are ubiquitous in the world's oceans and can make up as much as 11% of bacterial cells in certain areas. Isolated from coastal Oregon water,
Gammaproteobacteria
HTCC2148 and HTCC2080 are two members of this important clade. Here we present the genome sequences of the OM60
Gammaproteobacteria
HTCC2148 and HTCC2080.
Synthetic Effects ofsecGandsecY2Mutations on Exoproteome Biogenesis inStaphylococcus aureus
Authors: Sibbald Mark J. J. B. , Winter Theresa , van der Kooi-Pol Magdalena M. , Buist G. , Tsompanidou E. , Bosma Tjibbe , Schäfer Tina , Ohlsen Knut , Hecker Michael , Antelmann Haike , Engelmann Susanne , van Dijl Jan Maarten
Published: May 2010

The Gram-positive pathogenStaphylococcus aureussecretes various proteins into its extracellular milieu. Bioinformatics analyses have indicated that most of these proteins are directed to the canonical Sec pathway, which consists of the translocation motor SecA and a membrane-embedded channel composed of the SecY, SecE, and SecG proteins. In addition,S. aureuscontains an accessory Sec2 pathway involving the SecA2 and SecY2 proteins. Here, we have addressed the roles of the nonessential channel components SecG and SecY2 in the biogenesis of the extracellular proteome ofS. aureus. The results show that SecG is of major importance for protein secretion byS. aureus.Specifically, the extracellular accumulation of nine abundant exoproteins and seven cell wall-bound proteins was significantly affected in ansecGmutant. No secretion defects were detected for strains with asecY2single mutation. However, deletion ofsecY2exacerbated the secretion defects ofsecGmutants, affecting the extracellular accumulation of one additional exoprotein and one cell wall protein. Furthermore, ansecG secY2double mutant displayed a synthetic growth defect. This might relate to a slightly elevated expression ofsraP, encoding the only known substrate for the Sec2 pathway, in cells lacking SecG. Additionally, the results suggest that SecY2 can interact with the Sec1 channel, which would be consistent with the presence of a single set ofsecEandsecGgenes inS. aureus.
Transcriptional Analysis of the
grlRA
Virulence Operon from
Citrobacter rodentium
Authors: Tauschek Marija , Yang Ji , Hocking Dianna , Azzopardi Kristy , Tan Aimee , Hart Emily , Praszkier Judyta , Robins-Browne Roy M.
Published: May 2010

The locus for enterocyte effacement (LEE) is the virulence hallmark of the attaching-and-effacing (A/E) intestinal pathogens, namely, enteropathogenic
Escherichia coli
, enterohemorrhagic
E. coli
, and
Citrobacter rodentium
. The LEE carries more than 40 genes that are arranged in several operons, e.g.,
LEE1
to
LEE5
. Expression of the various transcriptional units is subject to xenogeneic silencing by the histone-like protein H-NS. The
LEE1
-encoded regulator, Ler, plays a key role in relieving this repression at several major LEE promoters, including
LEE2
to
LEE5
. To achieve appropriate intracellular concentrations of Ler in different environments, A/E pathogens have evolved a sophisticated regulatory network to control
ler
expression. For example, the LEE-encoded GrlA and GrlR proteins work as activator and antiactivator, respectively, of
ler
transcription. Thus, control of the transcriptional activities of the
LEE1
(
ler
) promoter and the
grlRA
operon determines the rate of transcription of all of the LEE-encoded virulence factors. To date, only a single promoter has been identified for the
grlRA
operon. In this study, we showed that the non-LEE-encoded AraC-like regulatory protein RegA of
C. rodentium
directly stimulates transcription of the
grlRA
promoter by binding to an upstream region in the presence of bicarbonate ions. In addition,
in vivo
and
in vitro
transcription assays revealed a σ
70
promoter that is specifically responsible for transcription of
grlA
. Expression from this promoter was strongly repressed by H-NS and its paralog StpA but was activated by Ler. DNase I footprinting demonstrated that Ler binds to a region upstream of the
grlA
promoter, whereas H-NS interacts specifically with a region extending from the
grlA
core promoter into its coding sequence. Together, these findings provide new insights into the environmental regulation and differential expressions of the
grlR
and
grlA
genes of
C. rodentium
.
Transcriptional Activation of the
tad
Type IVb Pilus Operon by PypB in
Yersinia enterocolitica
Authors: Schilling Jennifer , Wagner Karin , Seekircher Stephanie , Greune Lilo , Humberg Verena , Schmidt M. Alexander , Heusipp Gerhard
Published: May 2010

Type IV pili are virulence factors in various bacteria and mediate, among other functions, the colonization of diverse surfaces. Various subclasses of type IV pili have been identified, but information on pilus expression, biogenesis, and the associated phenotypes is sparse for the genus
Yersinia
. We recently described the identification of PypB as a transcriptional regulator in
Yersinia enterocolitica
. Here we show that the
pypB
gene is associated with the
tad
locus, a genomic island that is widespread among bacterial and archaeal species. The genetic linkage of
pypB
with the
tad
locus is conserved throughout the yersiniae but is not found among other bacteria carrying the
tad
locus. We show that the genes of the
tad
locus form an operon in
Y. enterocolitica
that is controlled by PypB and that
pypB
is part of this operon. The
tad
genes encode functions necessary for the biogenesis of the Flp subfamily of type IVb pili initially described for
Aggregatibacter actinomycetemcomitans
to mediate a tight-adherence phenotype. In
Y. enterocolitica
, the Flp pilin protein shows some peculiarities in its amino acid sequence that imply similarities as well as differences compared to typical motifs found in the Flp subtype of type IVb pili. Flp is expressed and processed after PypB overproduction, resulting in microcolony formation but not in increased adherence to biotic or abiotic surfaces. Our data describe the transcriptional regulation of the
tad
type IVb pilus operon by PypB in
Y. enterocolitica
but fail to show most previously described phenotypes associated with this type of pilus in other bacteria.
The emerging role of screen based simulators in the training and assessment of colonoscopists
Authors: Cunningham Morven , Fernando Bimbi , Berlingieri Pasquale
Published: May 2010

Incorporation of screen based simulators into medical training has recently gained momentum, as advances in technology have coincided with a government led drive to increase the use of medical simulation training to improve patient safety with progressive reductions in working hours available for junior doctors to train. High fidelity screen based simulators hold great appeal for endoscopy training. Potentially, their incorporation into endoscopy training curricula could enhance speed of acquisition of skills and improve patient comfort and safety during the initial phase of learning. They could also be used to demonstrate competence as part of the future relicensing and revalidation of trained endoscopists. Two screen based simulators are widely available for lower gastrointestinal endoscopy training, with a third recently produced in prototype. The utility of these simulators in lower gastrointestinal endoscopy training has been investigated, and construct and expert validity has been shown. Novices demonstrate a learning curve with simulator training that appears to represent real learning of colonoscopy skills. This learning transfers well to the real patient environment, with improvements in performance and patient discomfort scores in subsequent initial live colonoscopy. The significant limitations of currently available screen based simulators include cost implications, and restrictions on a role in certification and revalidation. Many questions remain to be answered by future research, including how best to incorporate screen based simulators into a colonoscopy training programme, their role in training in therapeutic endoscopy and the impact of simulator training on patient safety.
Capsule endoscopy: 10 years on and in the frontline
Authors: McAlindon M E , Sanders D S , Sidhu R
Published: May 2010

Capsule endoscopy is a safe, simple, remote method of visualising the gastrointestinal tract without resorting to conventional endoscopic intubation or radiation exposure. In addition, the ability to visualise the small bowel mucosa directly means that it is considerably more sensitive than existing small bowel imaging modalities in detecting subtle abnormalities. It is a firstline investigative modality for suspected small bowel bleeding and is being increasingly used for detecting evidence of other small bowel diseases. In Crohn's disease, it can confirm evidence of activity without recourse to repeated endoscopic intubation or radiation but does not replace MRI and CT which are better suited to defining stricturing disease and transmural complications. The production of different capsule endoscopes to examine the oesophagus, small bowel and colon now means that almost all of the gut can be examined using this technology.
Prolonged cholestasis induced by endoscopic retrograde cholangiopancreatography
Authors: Patani Olomuza , Foulkes Sian L , Njie Ramatoulie , Aspinall Richard J
Published: May 2010

The case of a 54-year-old woman who presented with choledocholithiasis and underwent successful endoscopic stone extraction to clear the common bile duct is described. However, her jaundice and liver biochemistry continued to deteriorate despite repeat endoscopic retrograde cholangiopancreatography (ERCP), with further imaging confirming a patent biliary tree. The clinical, radiological and pathological features were in keeping with prolonged cholestasis as a complication of ERCP. The pathophysiology of this unusual syndrome and the therapeutic options available are discussed.
Identifying small bowel intussusception related to a gastroenteric feeding tube
Authors: Al-Zubeidi Dina , Bishop Warren P , Rahhal Riad M
Published: May 2010

Enteral feedings through gastroenteric (GE) tubes are commonly utilised in patients with feeding difficulties and intolerance to gastric feeding. A variety of complications related to GE tubes have been described which rarely include small bowel intussusception. The case of a 23-year-old man with proximal small bowel intussusception related to an endoscopically placed low profile GE tube is described. The patient presented with abdominal pain and bilious vomiting. Symptoms resolved with tube shortening. This report includes a short review aimed at raising awareness about this complication with a discussion on diagnosis and management.
Hemostasis and obliteration of mandibular arteriovenous malformation through direct hydroxyapatite cement injection into the molar cavity
Authors: Gluncic Vicko , Reid Russell R , Baroody Fuad M , Gottlieb Lawrence J , Ansari Sameer A
Published: May 2010

A mandibular arteriovenous malformation (AVM) presented with massive molar socket bleeding and was emergently treated by tooth extraction and partial resection of the surrounding alveolar bone. To achieve hemostasis, the resultant cavity was filled with hydroxyapatite bone cement. Not only was hemostasis and alveolar reconstruction achieved, but follow-up angiography demonstrated venous outlet occlusion and retrograde AVM thrombosis requiring no further treatment.
FCTC guidelines on tobacco industry foreign investment would strengthen controls on tobacco supply and close loopholes in the tobacco treaty
Authors: Lo Chang-fa
Published: May 2010

The Framework Convention on Tobacco Control (FCTC) contains no provisions covering tobacco industry investments. This creates the potential for tobacco companies to benefit from investment liberalisation by using foreign investments to avoid tobacco tariffs, increase tobacco consumption and otherwise impair the implementation of FCTC-style measures. Reducing and ultimately eliminating foreign investment activities by tobacco companies can be justified on health grounds, even though it runs counter to current investment liberalisation trends. Through the FCTC process, non-binding guidelines can be elaborated to assist parties in recognising and responding to foreign investment strategies of tobacco companies, to support efforts to exclude the tobacco sector from investment liberalisation and otherwise would improve all countries' awareness of the threat from foreign investment strategies of tobacco companies and provide them with approaches to handle the problems.
How cost-effective is ‘No Smoking Day’?: Figure 1
Authors: Kotz D , Stapleton J A , Owen L , West R
Published: May 2010

Objective

To obtain a more rigorous estimate of the cost-effectiveness of No Smoking Day (NSD), an annual UK-wide campaign to encourage smokers to quit, than has been possible hitherto.

Design

Comparison of reported quit attempts in the month following NSD for three consecutive years with adjacent months using repeated national surveys of quit attempts.

Setting

England.

Participants

A total of 1309 adults who had smoked in the past year who responded to the surveys in the month following NSD (April 2007–2009) and a comparison group of 2672 adults who smoked in the past year who responded to the survey in the two adjacent months (March and May 2007–2009).

Main outcome measures

The number of additional smokers who quit permanently in response to NSD was estimated from the survey results. The incremental cost-effectiveness ratio (ICER) was calculated by combining this estimate with established estimates of life years gained and the known costs of NSD.

Results

The rate of quit attempts was 2.8 percentage points higher in the months following NSD (120/1309) compared with the adjacent months (170/2672; 95% CI 0.99% to 4.62%), leading to an estimated additional 0.07% of the 8.5 million smokers in England quitting permanently in response to NSD. The cost of NSD per smoker was £0.088. The discounted life years gained per smoker in the modal age group 35–44 years was 0.00107, resulting in an ICER of £82.24 (95% CI 49.7 to 231.6). ICER estimates for other age groups were similar.

Conclusions

NSD emerges as an extremely cost-effective public health intervention.
Tobacco point-of-sale displays in England: a snapshot survey of current practices
Authors: Rooke Catriona , Cheeseman Hazel , Dockrell Martin , Millward Deborah , Sandford Amanda
Published: May 2010

Background

Tobacco displays at the point of sale (PoS) are an important means for the tobacco industry to communicate with consumers. With regulations prohibiting PoS displays recently having come into force in Ireland, passed into law in England, Wales and Northern Ireland and some Australian states, and being considered in New Zealand, Finland and Brazil, this is an increasingly important issue. This study explores the nature of displays, the extent to which they are tobacco industry funded, and the relation between the tobacco companies and retailers.

Methods

Three areas were chosen to gain a snapshot of PoS displays in England. Over 100 retailers were visited, with interviews taking place on site. Information was gathered on the type and size of tobacco display, who was paying for the display, requirements and incentives, and visits by industry representatives.

Results

The majority of retailers had gantries provided by tobacco companies. A minority of these were fitted with automated dispensers called retail vending machines. Attractive lighting and colour were often used to highlight particular products. Most retailers were being visited by industry representatives who checked displays. Some retailers also reported incentives offered to them for displaying products.

Conclusions

The results suggest that the tobacco industry presence and control in the retail environment is significant. Tobacco companies overwhelmingly provided tobacco gantries in the shops surveyed and influenced displays through a combination of requirements and incentives. The extensive involvement of tobacco companies in providing and monitoring retail displays suggests the importance of implementing policies to end this form of advertising.
THE LOCALLY COVARIANT DIRAC FIELD
Authors: SANDERS KO
Published: May 2010

We describe the free Dirac field in a four-dimensional spacetime as a locally covariant quantum field theory in the sense of Brunetti, Fredenhagen and Verch, using a representation independent construction. The freedom in the geometric constructions involved can be encoded in terms of the cohomology of the category of spin spacetimes. If we restrict ourselves to the observable algebra, the cohomological obstructions vanish and the theory is unique. We establish some basic properties of the theory and discuss the class of Hadamard states, filling some technical gaps in the literature. Finally, we show that the relative Cauchy evolution yields commutators with the stress-energy-momentum tensor, as in the scalar field case.
INVERSE SCATTERING IN DE SITTER–REISSNER–NORDSTRÖM BLACK HOLE SPACETIMES
Authors: DAUDÉ THIERRY , NICOLEAU FRANÇOIS
Published: May 2010

In this paper, we study the inverse scattering of massive charged Dirac fields in the exterior region of (de Sitter)–Reissner–Nordström black holes. Firstly, we obtain a precise high-energy asymptotic expansion of the diagonal elements of the scattering matrix (i.e. of the transmission coefficients) and we show that the leading terms of this expansion allow to recover uniquely the mass, the charge and the cosmological constant of the black hole. Secondly, in the case of nonzero cosmological constant, we show that the knowledge of the reflection coefficients of the scattering matrix on any interval of energy also permits to recover uniquely these parameters.
STRUCTURE AND STABILITY OF ENDOHEDRAL Cn@C60
Authors: DEVI REENA , KUMAR RANJAN
Published: May 2010

We report ab initio molecular dynamics simulations of carbon clusters in free space and inside C 60 using SIESTA. We have studied the stability and geometries of small carbon clusters consisting of 2–12 carbon atoms inside the C 60 molecule and in free space by optimizing the atomic geometries. We have found that the C – C bond length is in agreement with the 1.40 and 1.45 values reported earlier. We find that the clusters inside the C 60 are more stable than clusters in free space. Binding energy per carbon atom initially increases with number of carbon atoms in the cluster and then decreases after maximizing for the 9-atom cluster. For more than 9 carbon atoms in the cluster inside C 60, C atoms of the cluster start forming bond with the C 60 cage and the C 60 structure gets distorted. We have done calculations for charge transfer and chemical reactivity. The calculations of ionization potential and electron affinity show that clusters in free space are less reactive compared with C n@ C 60. Charge transfer calculations show that the bond formation of C atoms with the C 60 cage is accompanied with a transfer of charge from carbon cluster to C 60.
ANGULAR DEPENDENCE OF UPPER CRITICAL FIELD FOR THE TWO-BAND SUPERCONDUCTOR Lu2Fe3Si5
Authors: LIU MINXIA , HUANG HAI
Published: May 2010

Based on the two-band Ginzburg–Landau theory, we study the angular dependence of the upper critical field for the superconducting crystal Lu 2 Fe 3 Si 5. When θ=0 and θ=π/2, the theoretical results are in good agreement with the experimental data. Hence, the results support the existence of two-gap superconductivity in Lu 2 Fe 3 Si 5, previously suggested from experiments.
${\mathcal H}_{\infty}$ WEIGHT LEARNING ALGORITHM OF RECURRENT NEURAL NETWORKS WITH TIME-DELAY
Authors: AHN CHOON KI
Published: May 2010

In this letter, we propose a new weight learning algorithm, called an [Formula: see text] learning law (HLL), for recurrent neural networks with time-delay. Based on the Lyapunov–Krasovskii stability theory, the HLL is presented to not only guarantee asymptotical stability but also reduce the effect of external disturbance to an [Formula: see text] norm constraint. An existence condition for the HLL is represented in terms of linear matrix inequality (LMI). An illustrative example is given to demonstrate the effectiveness of the proposed HLL.
THE NEW ADM–PADÉ TECHNIQUE FOR THE GENERALIZED EMDEN–FOWLER EQUATIONS
Authors: CHU HONGMEI , LIU YINPING
Published: May 2010

In this paper, the Emden–Fowler equations are investigated by employing the Adomian decomposition method (ADM) and the Padé approximant. By using the new type of Adomian polynomials proposed by Randolph C. Rach in 2008, our obtained solution series converges much faster than the regular ADM solution of the same order. Meanwhile, we note that the solutions obtained by using the new ADM–Padé technique have much higher accuracy and larger convergence domain than those obtained by using the regular ADM together with the Padé technique. Finally, comparison of our new obtained solutions are given with those existing exact ones graphically to illustrate the validity and the promising potential of the new ADM–Padé technique for solving nonlinear problems.
ON THE SPECTRUM OF A HOLOMORPHIC OPERATOR-VALUED FUNCTION WITH APPLICATIONS TO ABSORPTIVE PHOTONIC CRYSTALS
Authors: ENGSTRÖM CHRISTIAN
Published: May 2010

We study electromagnetic wave propagation in a periodic and frequency dependent material characterized by a space- and frequency-dependent complex-valued permittivity. The spectral parameter relates to the time-frequency, leading to spectral analysis of a holomorphic operator-valued function. We apply the Floquet transform and show for a fixed quasi-momentum that the resulting family of spectral problems has a spectrum consisting of at most countably many isolated eigenvalues of finite multiplicity. These eigenvalues depend continuously on the quasi-momentum and no nonzero real eigenvalue exists when the material is absorptive. Moreover, we reformulate the special case of a rational operator-valued function in terms of a polynomial operator pencil and study two-component dispersive and absorptive crystals in detail.
Short-term disruption in regional left ventricular electrical conduction patterns increases interstitial matrix metalloproteinase activity
Authors: Mukherjee Rupak , Zavadzkas Juozas A. , Rivers William T. , McLean Julie E. , Chang Eileen I. , Bouges Shenikqua , Matthews Robert G. , Koval Christine N. , Stroud Robert E. , Spinale Francis G.
Published: May 2010

Increased matrix metalloproteinase (MMP) abundance occurs with adverse left ventricular (LV) remodeling in a number of cardiac disease states, including those induced by long-standing arrhythmias. However, whether regionally contained aberrant electrical activation of the LV, with consequent dyskinesia, alters interstitial MMP activation remained unknown. Electrical activation of the LV of pigs ( n = 10, 30–35 kg) was achieved by pacing (150 beats/min) at left atrial and LV sites such that normal atrioventricular activation (60 min) was followed by regional early LV activation for 60 min within 1.5 cm of the paced site and restoration of normal atrioventricular pacing for 120 min. Regional shortening (piezoelectric crystals) and interstitial MMP activity (microdialysis with MMP fluorogenic substrate) at the LV pacing site and a remote LV site were monitored at 30-min intervals. During aberrant electrical stimulation, interstitial MMP activity at the paced site was increased (122 ± 4%) compared with the remote region (100%, P < 0.05). Restoration of atrioventricular pacing after the 60-min period of aberrant electrical activation normalized segmental shortening (8.5 ± 0.4%), but MMP activity remained elevated (121 ± 6%, P < 0.05). This study demonstrates that despite the restoration of mechanical function, disturbances in electrical conduction, in and of itself, can cause acute increases in regional in vivo MMP activation and, therefore, contribute to myocardial remodeling.
Enforced physical inactivity increases endothelial microparticle levels in healthy volunteers
Authors: Navasiolava Nastassia M. , Dignat-George Françoise , Sabatier Florence , Larina Irina M. , Demiot Claire , Fortrat Jacques-Olivier , Gauquelin-Koch Guillemette , Kozlovskaya Inesa B. , Custaud Marc-Antoine
Published: May 2010

A sedentary lifestyle has adverse effects on the cardiovascular system, including impaired endothelial functions. Subjecting healthy men to 7 days of dry immersion (DI) presented a unique opportunity to analyze the specific effects of enhanced inactivity on the endothelium. We investigated endothelial properties before, during, and after 7 days of DI involving eight subjects. Microcirculatory functions were assessed with laser Doppler in the skin of the calf. We studied basal blood flow and endothelium-dependent and -independent vasodilation. We also measured plasma levels of microparticles, a sign of cellular dysfunction, and soluble endothelial factors, reflecting the endothelial state. Basal flow and endothelium-dependent vasodilation were reduced by DI (22 ± 4 vs. 15 ± 2 arbitrary units and 29 ± 6% vs. 12 ± 6%, respectively, P < 0.05), and this was accompanied by an increase in circulating endothelial microparticles (EMPs), which was significant on day 3 (42 ± 8 vs. 65 ± 10 EMPs/μl, P < 0.05), whereas microparticles from other cell origins remained unchanged. Plasma soluble VEGF decreased significantly during DI, whereas VEGF receptor 1 and soluble CD62E were unchanged, indicating that the increase in EMPs was associated with a change in antiapoptotic tone rather than endothelial activation. Our study showed that extreme physical inactivity in humans induced by 7 days of DI causes microvascular impairment with a disturbance of endothelial functions, associated with a selective increase in EMPs. Microcirculatory endothelial dysfunction might contribute to cardiovascular deconditioning as well as to hypodynamia-associated pathologies. In conclusion, the endothelium should be the focus of special care in situations of acute limitation of physical activity.
X-linked inhibitor of apoptosis protein controls α5-integrin-mediated cell adhesion and migration
Authors: Kim Jongmin , Ahn Sunyoung , Ko Young-Gyu , Boo Yong Chool , Chi Sung-Gil , Ni Chih-Wen , Go Young-Mi , Jo Hanjoong , Park Heonyong
Published: May 2010

The association of integrins with caveolin-1 regulates cell adhesion. However, the vascular ramifications of this association remain to be clearly determined. We recently reported that the X chromosome-linked inhibitor of apoptosis protein (XIAP)-caveolin-1 interaction is critical to endothelial cell survival. Thus, we hypothesized that XIAP performs a crucial function in integrin/caveolin-1-mediated endothelial cell survival. In this study, we demonstrated that XIAP is recruited into the α5-integrin complex via caveolin-1 binding and mediates cell adhesion. We also determined that XIAP is critical to shear stress-stimulated ERK activation in an α5-integrin-dependent manner but is not important to VEGF-induced ERK activation. This differential activation of ERK is partly attributable to unique localizations of the receptors. Furthermore, we confirmed that XIAP is an essential molecule in the efficient recruitment of focal adhesion kinase (FAK) into the α5-integrin-associated complex. This α5-integrin-caveolin-1-XIAP-FAK multicomplex regulates endothelial cell migration via a mechanism that involves shear-dependent ERK activation. Together, our results indicate that XIAP stabilizes the α5-integrin-associated focal adhesion complex, thereby further regulating endothelial cell adhesion and migration. The findings of this study provide us with greater insight into the molecular mechanisms underlying the control of vascular function by integrins.
Role of lysyl oxidase in myocardial fibrosis: from basic science to clinical aspects
Authors: López Begoña , González Arantxa , Hermida Nerea , Valencia Félix , de Teresa Eduardo , Díez Javier
Published: May 2010

Because of its dynamic nature, the composition and structure of the myocardial collagen network can be reversibly modified to adapt to transient cardiac injuries. In response to persistent injury, however, irreversible, maladaptive changes of the network occur leading to fibrosis, mostly characterized by the excessive interstitial and perivascular deposition of collagen types I and III fibers. It is now becoming apparent that myocardial fibrosis directly contributes to adverse myocardial remodeling and the resulting alterations of left ventricular (LV) anatomy and function present in the major types of cardiac diseases. The enzyme lysyl oxidase (LOX) is a copper-dependent extracellular enzyme that catalyzes lysine-derived cross-links in collagen and elastin. LOX-mediated cross-linking of collagen types I and III fibrils leads to the formation of stiff collagen types I and III fibers and their subsequent tissue deposition. Evidence from experimental and clinical studies shows that the excess of LOX is associated with an increased collagen cross-linking and stiffness. It is thus conceivable that LOX upregulation and/or overactivity could underlie myocardial fibrosis and altered LV mechanics and contribute to the compromise of LV function in cardiac diseases. This review will consider the molecular aspects related to the regulation and actions of LOX, namely, in the context of collagen synthesis. In addition, it will address the information related to the role of myocardial LOX in heart failure and the potential benefits of controlling its expression and function.
The mechanism by which RhoA regulates vascular reactivity after hemorrhagic shock in rats
Authors: Li Tao , Fang Yuqiang , Yang Guangming , Zhu Yu , Xu Jing , Liu Liangming
Published: May 2010

RhoA, an important member of the Rho family of GTPases, has been implicated in many cellular processes. Our pilot study found that RhoA participated in the regulation of vascular reactivity after shock, but the mechanism was incompletely understood. Whether RhoA regulates vascular reactivity through the Rho kinase-myosin light-chain phosphatase (MLCP) and Rac1-p21-activated kinase (PAK)-myosin light-chain kinase (MLCK) signaling pathway needs investigation. With isolated, superior mesenteric arteries from hemorrhagic-shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs), the effects of U-46619 (RhoA agonist) and C3 transferase (RhoA antagonist) on vascular reactivity, and the relationship to the Rho kinase-MLCP and Rac1-PAK-MLCK signaling pathways were observed. The vascular reactivity of the superior mesenteric artery and the contractile response of VSMCs to norepinephrine after prolonged hemorrhagic shock and hypoxia (2 h) were significantly decreased. Activation of RhoA with U-46619 significantly increased shock or hypoxia-induced decreased vascular reactivity. These effects of U-46619 were abolished by Y-27632 (Rho kinase inhibitor) and PDGF (Rac1 stimulator). Y-27632 had a stronger antagonistic effect than PDGF. U-46619 increased the activity of Rho kinase and MLCK, enhanced the phosphorylation of 20-kDa myosin light chain, and decreased the activity of Rac1, PAK, and MLCP in VSMCs after hypoxia. Y-27632-antagonized U-46619 induced the decrease of MLCP activity and the increase of 20-kDa myosin light chain phosphorylation. PDGF-antagonized U-46619 induced decrease of PAK activity and increase of MLCK activity. RhoA has an important role in the regulation of vascular reactivity after hemorrhagic shock. The Rho kinase-MLCP and Rac1-PAK-MLCK signal pathways participate in the regulatory process of RhoA. Rho kinase-MLCP may be the main signaling pathway by which RhoA regulates vascular reactivity.
Importance of lymph vessels in the transcapillary fluid balance in the gingiva studied in a transgenic mouse model
Authors: Mkonyi Lilian Ephrem , Bletsa Athanasia , Fristad Inge , Wiig Helge , Berggreen Ellen
Published: May 2010

The gingiva is frequently challenged by oral bacterial products leading to inflammatory responses such as increased fluid filtration and edema formation. The role of initial lymphatics for transcapillary fluid balance in the gingiva is unknown and was therefore investigated in genetically engineered K14-VEGF receptor 3-Ig (K14) lymphedema mice. The mutant mice demonstrated a total lack of lymphatics in the gingiva, whereas lymphatics were found in the submucosal parts of the alveolar mucosa, although they were almost completely absent in the mucosa. In wild-type (WT) mice, lymphatic vessels were detected in mucosal and submucosal parts of the alveolar mucosa. Interstitial fluid pressure (Pif) measured with micropipettes was increased in the gingiva of K14 mice in the normal situation ( P < 0.001) and after inflammation ( P < 0.01) induced by lipopolysaccharide from the oral bacteria Porphyromonas gingivalis compared with WT littermates. Fluid volume expansion caused a >75% increase in interstitial fluid volume followed by a drop in Pifafter recovery in both strains. Continuous measurements during the expansion showed an increase in Piffollowed by a decline, suggesting that compliance is increased after the disruption of the extracellular matrix during edema formation. In the alveolar mucosa, no strain differences were observed in Pifin the normal situation or after fluid volume expansion, suggesting that lymph vessels in the mucosa are not critical for tissue fluid regulation in any situation. Our study demonstrates an important role of gingival lymphatics in transcapillary fluid balance in the steady-state condition and during acute perturbations.
Anti-inflammatory effects of celecoxib in rat lungs with smoke-induced emphysema
Authors: Roh Gu Seob , Yi Chin-ok , Cho Yu Ji , Jeon Byeong Tak , Nizamudtinova Irina Tsoy , Kim Hye Jung , Kim Jin Hyun , Oh Yeon-Mok , Huh Jin Won , Lee Ji-Hyun , Hwang Young Sil , Lee Sang Do , Lee Jong Deog
Published: May 2010

Chronic airway inflammation is a characteristic feature of destructive cigarette smoking (CS)-induced lung disease, particularly in patients with emphysema. Celecoxib, a specific cyclooxygenase-2 (COX-2) inhibitor, is widely used to treat inflammation. However, the exact mechanisms underlying this drug's anti-inflammatory effects have not yet been determined in pulmonary emphysema. Here, we explore whether celecoxib attenuates CS-induced inflammation in rat lungs. Rats were exposed to smoke and received celecoxib via intragastric feeding daily for 20 wk. We found that celecoxib inhibited interalveolar wall distance and pulmonary inflammation in the lungs of CS-treated rats. Celecoxib inhibited serum NO production, iNOS, COX-2 expression, and PGE2production in CS-treated lung tissues. Our immunohistochemical data showed that CS-induced CD68 and COX-2 expression were inhibited by celecoxib. Furthermore, celecoxib attenuated the activation of phospho-IκBα and NF-κB in CS-treated rat lung. In addition, there was an inhibitory effect of celecoxib on the COX-2 expression and NF-κB activation in LPS-stimulated RAW 264.7 macrophages. Celecoxib also attenuated NF-κB activation in COX-2 siRNA-transfected RAW 264.7 macrophages. Thus, our findings suggest that the anti-inflammatory effects of celecoxib are mediated by its effects on NF-κB-regulated gene expression, which ultimately reduces the progression of CS-induced pulmonary emphysema.
Glutaredoxin 1 regulates cigarette smoke-mediated lung inflammation through differential modulation of IκB kinases in mice: impact on histone acetylation
Authors: Chung Sangwoon , Sundar Isaac Kirubakaran , Yao Hongwei , Ho Ye-Shih , Rahman Irfan
Published: May 2010

Glutaredoxin 1 (Glrx1) is a small dithiol protein that regulates the cellular redox state and redox-dependent signaling pathways via modulation of protein glutathionylation. IκB kinase (IKK), an essential enzyme for NF-κB activation, can be subjected to S-glutathionylation leading to alteration of its activity. However, the role of Glrx1 in cigarette smoke (CS)-induced lung inflammation and chromatin modifications are not known. We hypothesized that Glrx1 regulates the CS-induced lung inflammation and chromatin modifications via differential regulation of IKKs by S-glutathionylation in mouse lung. Glrx1 knockout (KO) and wild-type (WT) mice were exposed to CS for 3 days and determined the role of Glrx1 in regulation of proinflammatory response in the lung. Neutrophil influx in bronchoalveolar lavage fluid and proinflammatory cytokine release in lung were increased in Glrx1 KO mice compared with WT mice exposed to CS, which was associated with augmented nuclear translocation of RelA/p65 and its phospho-acetylation. Interestingly, phosphorylated and total levels of IKKα, but not total and phosphorylated IKKβ levels, were increased in lungs of Glrx1 KO mice compared with WT mice exposed to CS. Ablation of Glrx1 leads to increased CS-induced IKKβ glutathionylation rendering it inactive, whereas IKKα was activated resulting in increased phospho-acetylation of histone H3 in mouse lung. Thus, targeted disruption of Glrx1 regulates the lung proinflammatory response via histone acetylation specifically by activation of IKKα in response to CS exposure. Overall, our study suggests that S-glutathionylation and phosphorylation of IKKα plays an important role in histone acetylation on proinflammatory gene promoters and NF-κB-mediated abnormal and sustained lung inflammation in pathogenesis of chronic inflammatory lung diseases.
Effect of pravastatin on ventricular arrhythmias in infarcted rats: role of connexin43
Authors: Chen Chien-Chang , Lien Hsiao-Yin , Hsu Yu-Jung , Lin Chih-Chan , Shih Chun-Ming , Lee Tsung-Ming
Published: May 2010

Epidemiologic studies showed that men treated with statins appear to have a lower incidence of sudden death than men without statins. However, the specific factor for this remained disappointingly elusive. We assessed whether pravastatin enhanced connexin43 expression after myocardial infarction through attenuation of endothelin-1. Twenty-four hours after ligation of the anterior descending artery, male Wistar rats were randomized to vehicle, pravastatin, mevalonate, bosentan, or a combination of pravastatin and mevalonate or pravastatin and bosentan for 4 wk. Myocardial endothelin-1 levels were significantly elevated in vehicle-treated rats at the border zone compared with sham-operated rats. Myocardial connexin43 expression at the border zone was significantly decreased in vehicle-treated infarcted rats compared with sham-operated rats. Attenuated connexin43 expression was blunted after administration of pravastatin, as assessed by immunofluorescence analysis, Western blotting, and real-time quantitative RT-PCR of connexin43. Bosentan enhanced connexin43 amount in infarcted rats and did not have additional beneficial effects on pravastatin-treated rats. Arrhythmic scores during programmed stimulation in vehicle-treated rats were significantly higher than scores in those treated with pravastatin. In contrast, the beneficial effects of pravastatin-induced connexin43 were abolished by the addition of mevalonate and a protein kinase C inducer. In addition, the amount of connexin43 showed significant increase after addition of bisindolylmaleimide, implicating that protein kinase C is a relevant target in endothelin-1-mediated connexin43 expression. Thus chronic use of pravastatin after infarction, resulting in enhanced connexin43 amount by attenuation of mevalonate-dependent endothelin-1 through a protein kinase C-dependent pathway, may attenuate the arrhythmogenic response to programmed electrical stimulation.
Targeting the Mitogen-Activated Protein Kinase Pathway: Physiological Feedback and Drug Response
Authors: Pratilas Christine A. , Solit David B.
Published: May 2010

Mitogen-activated protein kinase (MAPK) pathway activation is a frequent event in human cancer and is often the result of activating mutations in the BRAF and RAS oncogenes. Targeted inhibitors of BRAF and its downstream effectors are in various stages of preclinical and clinical development. These agents offer the possibility of greater efficacy and less toxicity than current therapies for tumors driven by oncogenic mutations in the MAPK pathway. Early clinical results with the BRAF-selective inhibitor PLX4032 suggest that this strategy will prove successful in a select group of patients whose tumors are driven by V600E BRAF. Relief of physiologic feedback upon pathway inhibition may, however, attenuate drug response and contribute to the development of acquired resistance. An improved understanding of the adaptive response of cancer cells to MAPK pathway inhibition may thus aid in the identification of those patients most likely to respond to targeted pathway inhibitors and provide a rational basis for tailored combination strategies. Clin Cancer Res; 16(13); 3329–34. ©2010 AACR.
Rapid and Robust Transgenic High-Grade Glioma Mouse Models for Therapy Intervention Studies
Authors: de Vries Nienke A. , Bruggeman Sophia W. , Hulsman Danielle , de Vries Hilda I. , Zevenhoven John , Buckle Tessa , Hamans Bob C. , Leenders William P. , Beijnen Jos H. , van Lohuizen Maarten , Berns Anton J.M. , van Tellingen Olaf
Published: May 2010

Purpose: To develop a transgenic mouse model of glioma that can be conveniently used for testing therapy intervention strategies. High-grade glioma is a devastating and uniformly fatal disease for which better therapy is urgently needed. Typical for high-grade glioma is that glioma cells infiltrate extensively into surrounding pivotal brain structures, thereby rendering current treatments largely ineffective. Evaluation of novel therapies requires the availability of appropriate glioma mouse models.

Experimental Design: High-grade gliomas were induced by stereotactic intracranial injection of lentiviral GFAP-Cre or CMV-Cre vectors into compound LoxP-conditional mice, resulting in K-Rasv12 expression and loss of p16Ink4a/p19Arf with or without concomitant loss of p53 or Pten.

Results: Tumors reproduced many of the features that are characteristic for human high-grade gliomas, including invasiveness and blood-brain barrier functionality. Especially, CMV-Cre injection into p53;Ink4a/Arf;K-Rasv12 mice resulted in high-grade glioma with a short tumor latency (2-3 weeks) and full penetrance. Early detection and follow-up was accomplished by noninvasive bioluminescence imaging, and the practical utility for therapy intervention was shown in a study with temozolomide.

Conclusion: We have developed a realistic high-grade glioma model that can be used with almost the same convenience as traditional xenograft models, thus allowing its implementation at the forefront of preclinical evaluation of new treatments. Clin Cancer Res; 16(13); 3431–41. ©2010 AACR.
A Functional Variant of Tandem Repeats in Human Telomerase Gene Was Associated with Survival of Patients with Early Stages of Non–Small Cell Lung Cancer
Authors: Wang Luo , Wang Li-E , Mao Li , Spitz Margaret R. , Wei Qingyi
Published: May 2010

Purpose: Elevated levels of human telomerase (hTERT) mRNA in tumors is a marker for poorer survival in patients with stage I non–small cell lung cancer (NSCLC). A functional variant of MNS16A-short tandem repeats in hTERT (S allele) is associated with higher expression levels of hTERT mRNA compared with the MNS16A-long (L) allele. It is unknown, however, whether or not the hTERT MNS16A variant genotype predicts survival of NSCLC patients.

Experimental Design: The hTERT genotypes of 808 patients with NSCLC were determined by direct PCR with genomic DNA. Overall median survival times were estimated by the life-table method, and the log-rank test was used to test for homogeneity of the survival curves. Both univariate and multivariate Cox proportional hazards models were used to assess the associations between survival time and the hTERT genotype as well as other known risk factors.

Results: The hTERT variant genotype was not associated with overall survival among the 808 patients. However, among 221 patients with stage I or II NSCLC, the S allele was associated with shorter survival time (P = 0.027, by log-rank test). The adjusted hazard ratios were 1.30 (95% confidence interval, 0.79-2.14; P = 0.310) for the SL-genotype and 2.34 (95% confidence interval, 1.20-4.56, P = 0.012) for the SS-genotype compared with the LL-genotype (P = 0.021 for trend test). These findings were not evident in 587 patients with stage III or IV NSCLC.

Conclusion: The functional MNS16A-SS genotype may be a marker for poorer survival in early-stage NSCLC. Clin Cancer Res; 16(14); 3779–85. ©2010 AACR.