bluuebunny/crossref_metadata_2025 huggingface dataset:
Conditions That Diminish Myeloid-Derived Suppressor Cell Activities Stimulate Cross-Protective Immunity
Authors: Heithoff Douglas M. , Enioutina Elena Y. , Bareyan Diana , Daynes Raymond A. , Mahan Michael J.
Published: September 2008

Immunity conferred by conventional vaccines is restricted to a narrow range of closely related strains, highlighting the unmet medical need for the development of vaccines that elicit protection against multiple pathogenic serotypes. Here we show that aSalmonellabivalent vaccine comprised of strains that lack and overproduce DNA adenine methylase (Dam) conferred cross-protective immunity to salmonella clinical isolates of human and animal origin. Protective immunity directly correlated with increased levels of cross-reactive opsonizing antibodies and memory T cells and a diminished expansion of myeloid-derived suppressor cells (MDSCs) that are responsible for the immune suppression linked to several conditions of host stress, including chronic microbial infections, traumatic insults, and many forms of cancer. Further, aged mice contained increased numbers of MDSCs and were more susceptible toSalmonellainfection than young mice, suggesting a role for these cells in the immune declines associated with the natural aging process. These data suggest that interventions capable of reducing MDSC presence and activities may allow corresponding increases in B- and T-cell stimulation and benefit the ability of immunologically diverse populations to be effectively vaccinated as well as reducing the risk of susceptible individuals to infectious disease.
RegA, an AraC-Like Protein, Is a Global Transcriptional Regulator That Controls Virulence Gene Expression in
Citrobacter rodentium
Authors: Hart Emily , Yang Ji , Tauschek Marija , Kelly Michelle , Wakefield Matthew J. , Frankel Gad , Hartland Elizabeth L. , Robins-Browne Roy M.
Published: September 2008

Citrobacter rodentium
is an attaching and effacing pathogen which causes transmissible colonic hyperplasia in mice. Infection with
C. rodentium
serves as a model for infection of humans with enteropathogenic and enterohemorrhagic
Escherichia coli
. To identify novel colonization factors of
C. rodentium
, we screened a signature-tagged mutant library of
C. rodentium
in mice. One noncolonizing mutant had a single transposon insertion in an open reading frame (ORF) which we designated
regA
because of its homology to genes encoding members of the AraC family of transcriptional regulators. Deletion of
regA
in
C. rodentium
resulted in markedly reduced colonization of the mouse intestine. Examination of
lacZ
transcriptional fusions using promoter regions of known and putative virulence-associated genes of
C. rodentium
revealed that RegA strongly stimulated transcription of two newly identified genes located close to
regA
, which we designated
adcA
and
kfcC
. The cloned
adcA
gene conferred autoaggregation and adherence to mammalian cells to
E. coli
strain DH5α, and a
kfc
mutation led to a reduction in the duration of intestinal colonization, but the
kfc
mutant was far less attenuated than the
regA
mutant. These results indicated that other genes of
C. rodentium
whose expression required activation by RegA were required for colonization. Microarray analysis revealed a number of RegA-regulated ORFs encoding proteins homologous to known colonization factors. Transcription of these putative virulence determinants was activated by RegA only in the presence of sodium bicarbonate. Taken together, these results show that RegA is a global regulator of virulence in
C. rodentium
which activates factors that are required for intestinal colonization.
Responses of Cattle to Gastrointestinal Colonization by
Escherichia coli
O157:H7
Authors: Nart Pablo , Naylor Stuart W. , Huntley John F. , McKendrick Iain J. , Gally David L. , Low J. Christopher
Published: September 2008

Recent research has established that the terminal rectum is the predominant colonization site of enterohemorrhagic
Escherichia coli
O157:H7 in cattle. The main aim of the present work was to investigate pathological changes and associated immune responses at this site in animals colonized with
E. coli
O157:H7. Tissue and gastrointestinal samples from a total of 22 weaned Holstein-cross calves challenged with
E. coli
O157:H7 were analyzed for bacterial colonization and pathology. Five unexposed age-matched calves were used as comparative negative controls.
E. coli
O157:H7 bacteria induced histopathological alterations of the rectal mucosa with enterocyte remodeling. This was often associated with removal of the colonized epithelial layer. Immunogold labeling and transmission electron microscopy (TEM) showed
E. coli
O157 bacteria on pedestals, as part of attaching and effacing lesions. These pathological changes induced a local infiltration of neutrophils that was quantified as larger in infected animals. Rectal mucosal immunoglobulin A responses were detected against the
E. coli
O157:H7 antigen. This work presents evidence that
E. coli
O157:H7 is not a commensal bacteria in the bovine host and that the mucosal damage produced by
E. coli
O157:H7 colonization of the terminal rectum induces a quantifiable innate immune response and production of specific mucosal antibodies.
Analysis of the Isoprenoid Biosynthesis Pathways in
Listeria monocytogenes
Reveals a Role for the Alternative 2-C-Methyl-
d
-Erythritol 4-Phosphate Pathway in Murine Infection
Authors: Begley Máire , Bron Peter A. , Heuston Sinead , Casey Pat G. , Englert Nadine , Wiesner Jochen , Jomaa Hassan , Gahan Cormac G. M. , Hill Colin
Published: September 2008

Most bacteria synthesize isoprenoids through one of two essential pathways which provide the basic building block, isopentyl diphosphate (IPP): either the classical mevalonate pathway or the alternative non-mevalonate 2-C-methyl-
d
-erythritol 4-phosphate (MEP) pathway. However, postgenomic analyses of the
Listeria monocytogenes
genome revealed that this pathogen possesses the genetic capacity to produce the complete set of enzymes involved in both pathways. The nonpathogenic species
Listeria innocua
naturally lacks the last two genes (
gcpE
and
lytB
) of the MEP pathway, and bioinformatic analyses strongly suggest that the genes have been lost through evolution. In the present study we show that heterologous expression of
gcpE
and
lytB
in
L. innocua
can functionally restore the MEP pathway in this organism and confer on it the ability to induce Vγ9Vδ2 T cells. We have previously confirmed that both pathways are functional in
L. monocytogenes
and can provide sufficient IPP for normal growth in laboratory media (M. Begley, C. G. Gahan, A. K. Kollas, M. Hintz, C. Hill, H. Jomaa, and M. Eberl, FEBS Lett. 561:99-104, 2004). Here we describe a targeted mutagenesis strategy to create a double pathway mutant in
L. monocytogenes
which cannot grow in the absence of exogenously provided mevalonate, confirming the requirement for at least one intact pathway for growth. In addition, murine studies revealed that mutants lacking the MEP pathway were impaired in virulence relative to the parent strain during intraperitoneal infection, while mutants lacking the classical mevalonate pathway were not impaired in virulence potential. In vivo bioluminescence imaging also confirmed in vivo expression of the
gcpE
gene (MEP pathway) during murine infection.
Enhanced Microscopic Definition of
Campylobacter jejuni
81-176 Adherence to, Invasion of, Translocation across, and Exocytosis from Polarized Human Intestinal Caco-2 Cells
Authors: Hu Lan , Tall Ben D. , Curtis Sherill K. , Kopecko Dennis J.
Published: September 2008

Campylobacter jejuni
-mediated pathogenesis involves gut adherence and translocation across intestinal cells. The current study was undertaken to examine the
C. jejuni
interaction with and translocation across differentiated Caco-2 cells to better understand
Campylobacter
's pathogenesis. The efficiency of
C. jejuni
81-176 invasion of Caco-2 cells was two- to threefold less than the efficiency of invasion of INT407 cells. Adherence-invasion analyses indicated that
C. jejuni
81-176 adhered to most INT407 cells but invaded only about two-thirds of the host cells over 2 h (two bacteria/cell). In contrast, only 11 to 17% of differentiated Caco-2 cells were observed to bind and internalize either
C. jejuni
strain 81-176 or NCTC 11168, and a small percentage of infected Caco-2 cells contained 5 to 20 internalized bacteria per cell after 2 h. Electron microscopy revealed that individual
C. jejuni
cells adhered to the tips of host cell microvilli via intimate flagellar contacts and by lateral bacterial binding to the sides of microvilli. Next, bacteria were observed to bind at the apical host membrane surface via presumed interactions at one pole of the bacterium and with host membrane protrusions located near intercellular junctions. The latter contacts apparently resulted in coordinated, localized plasma membrane invagination, causing simultaneous internalization of bacteria into an endosome. Passage of this
Campylobacter
endosome intracellularly from the apical surface to the basolateral surface occurred over time, and bacterial release apparently resulted from endosome-basolateral membrane fusion (i.e., exocytosis). Bacteria were found intercellularly below tight junctions at 60 min postinfection, but not at earlier times. This study revealed unique host cell adherence contacts, early endocytosis-specific structures, and a presumptive exocytosis component of the transcellular transcytosis route.
Intestinal Adherence of
Vibrio cholerae
Involves a Coordinated Interaction between Colonization Factor GbpA and Mucin
Authors: Bhowmick Rudra , Ghosal Abhisek , Das Bhabatosh , Koley Hemanta , Saha Dhira Rani , Ganguly Sandipan , Nandy Ranjan K. , Bhadra Rupak K. , Chatterjee Nabendu Sekhar
Published: September 2008

The chitin-binding protein GbpA of
Vibrio cholerae
has been recently described as a common adherence factor for chitin and intestinal surface. Using an isogenic in-frame
gbpA
deletion mutant, we first show that
V. cholerae
O1 El Tor interacts with mouse intestinal mucus quickly, using GbpA in a specific manner. The
gbpA
mutant strain showed a significant decrease in intestinal adherence, leading to less colonization and fluid accumulation in a mouse in vivo model. Purified recombinant GbpA (rGbpA) specifically bound to
N
-acetyl-
d
-glucosamine residues of intestinal mucin in a dose-dependent, saturable manner with a dissociation constant of 11.2 μM. Histopathology results from infected mouse intestine indicated that GbpA binding resulted in a time-dependent increase in mucus secretion. We found that rGbpA increased the production of intestinal secretory mucins (MUC2, MUC3, and MUC5AC) in HT-29 cells through upregulation of corresponding genes. The upregulation of
MUC2
and
MUC5AC
genes was dependent on NF-κB nuclear translocation. Interestingly, mucin could also increase GbpA expression in
V. cholerae
in a dose-dependent manner. Thus, we propose that there is a coordinated interaction between GbpA and mucin to upregulate each other in a cooperative manner, leading to increased levels of expression of both of these interactive factors and ultimately allowing successful intestinal colonization and pathogenesis by
V. cholerae
.
Comparison between confocal scanning laser tomography, scanning laser polarimetry and optical coherence tomography on the ability to detect localised retinal nerve fibre layer defects in glaucoma patients
Authors: Windisch B K , Harasymowycz P J , See J L , Chauhan B C , Belliveau A C , Hutchison D M , Nicolela M T
Published: September 2008

Background/aim:

To compare the ability of confocal scanning laser tomography (CSLT), scanning laser polarimetry (SLP) and optical coherence tomography (OCT) in recognising localised retinal nerve fibre layer (RNFL) defects.

Methods:

51 eyes from 43 patients with glaucoma were identified by two observers as having RNFL defects visible on optic disc photographs. 51 eyes of 32 normal subjects were used as controls. Three masked observers evaluated CSLT, SLP and OCT images to determine subjectively the presence of localised RNFL defects.

Results:

Interobserver agreement was highest with OCT, followed by SLP and CSLT (mean kappa: 0.83, 0.69 and 0.64, respectively). RNFL defects were identified in 58.8% of CSLT, 66.7% of SLP and 54.9% of OCT (p = 0.02 between SLP and OCT) by at least two observers. In the controls, 94.1% of CSLT, 84.3% of SLP and 94.1% of OCT scans, respectively, were rated as normal (p = 0.02 between CSLT and SLP, and SLP and OCT).

Conclusion:

Approximately 20–40% of localised RNFL defects identified by colour optic disc photographs are not detected by CSLT, SPL or OCT. SLP showed a higher number of false-positive results than the other techniques, but also had a higher proportion of correctly identified RNFL defects in the glaucoma population.
Epigenetic dysregulation of the Wnt signalling pathway in chronic lymphocytic leukaemia
Authors: Chim C S , Pang R , Liang R
Published: September 2008

Background:

Wnt signalling has recently been implicated in the pathogenesis of cancer.

Methods:

This study investigated the activity of Wnt signalling in peripheral blood chronic lymphocytic leukaemia (CLL) lymphocytes, and the methylation status of seven soluble Wnt antagonist genes, includingWIF1, DKK3, APC, SFRP1, SFRP2, SFRP4andSFRP5, by using methylation-specific PCR in the peripheral blood CLL lymphocytes and bone marrow samples of patients with CLL at diagnosis.

Results:

In the peripheral blood CLL lymphocytes, constitutive activation of Wnt signalling was detected, associated with hypermethylation of the soluble Wnt inhibitor genes. In the diagnostic CLL marrow samples, methylation of the seven genes was detected in up to 36.4% of samples. Moreover, 23 (52.3%) patients had methylation of at least one of the seven genes, of whom 14 (60.8%) had methylation of two or more Wnt inhibitor genes. Apart from an association of advanced age withDKK3methylation, there was no association of gene hypermethylation with either clinical characteristics (including age, gender, lymphocyte count at diagnosis, Rai stage and poor-risk karyotype) or survival.

Conclusion:

Wnt signalling is constitutively activated in CLL B lymphocytes in association with methylation of multiple soluble Wnt antagonist genes. Methylation of these soluble Wnt antagonist genes, occasionally multiple genes, in primary CLL marrow samples suggests an important role in CLL pathogenesis. Moreover, this study underscored the importance of studying methylation of a panel of, but not individual, genes regulating a cellular pathway.
Ignoring puff counts: another shortcoming of the Federal Trade Commission cigarette testing programme
Authors: Kozlowski L T , Whetzel C A , Stellman S D , O’Connor R J
Published: September 2008

Objectives:

To examine reasons behind the failure of the Federal Trade Commission (FTC) to preserve puff count information from standard cigarette testing and to elucidate the importance of puff count to overall tar yields.

Methods:

We reviewed industry documents on origins of the FTC test and datasets provided by the Tobacco Institute Testing Laboratory to the tobacco industry and FTC for reporting purposes.

Results:

The majority of the tobacco industry argued for “dual reporting” of tar yields—both per cigarette and per puff. Despite a request from the Tobacco Institute in 1967 that puff count information be preserved, documents and recent communications with the FTC indicate that puff number data have not been maintained by the government. In contrast, for the cigarette industry, puff count data are a fundamental and routine part of testing and important to cigarette design. A sample of puff counts for cigarettes tested in 1996 (n = 471) shows that on average 100 mm cigarettes have 18% more puffs taken on them than do 85 mm cigarettes in standard tests (7.66 vs 9.03; p<0.01). The 10th percentile puff count is 6.8 and the 90th percentile is 8.8 for king size; the 10th percentile puff count is 8.2 and the 90th percentile is 10.0 for 100 mm cigarettes, indicating that puff counts can vary substantially among brands.

Conclusions:

The FTC has failed to seek or preserve puff count information that the industry finds important. Any standard test of tar and nicotine yields should at minimum preserve puff count information.
The feasibility of measuring puffing behaviour in roll-your-own cigarette smokers
Authors: Shahab L , West R , McNeill A
Published: September 2008

Background/objective:

Despite the increase in roll-your-own (RYO) cigarette consumption in many countries, very little is known about RYO smokers. In order to estimate the health risks inherent in RYO use, it is important to assess exposure to tobacco toxins in this group. Exposure is determined by a number of factors, including puffing behaviour, but so far this issue has not been addressed among RYO smokers. This study sought both to determine the feasibility of measuring puffing behaviour in this group, its reliability and validity, and to characterise puffing behaviour among RYO smokers compared with smokers of factory-made (FM) cigarettes.

Methods:

At two visits, 24 hours apart, 131 FM and 29 RYO cigarette smokers provided saliva samples that were assayed for cotinine, a measure of nicotine intake and thus smoke exposure. Self-reported puffing behaviour of participants, as well as their demographic and smoking characteristics were also assessed. At the end of the first visit, smokers were shown how to use a portable smoking topography machine that measures puffing behaviour, the CReSSmicro, and asked to smoke all cigarettes with this machine until the second visit, when participants were asked to provide feedback on using the device.

Results:

Both RYO and FM cigarette smokers reported that the CReSSmicro was easy to use; however, RYO cigarette smokers were more likely to have missing data, to reduce cigarette consumption and to indicate a change in their puffing behaviour because of the device. Machine-determined puffing behaviour was equally stable over time in both groups with similar ability to predict exposure; cotinine levels were related to machine but not to self-reported puffing parameters. Overall, RYO smokers appeared to puff cigarettes less hard but for longer than FM cigarette smokers.

Conclusion:

The measurement of puffing behaviour using a topography device is feasible but less practicable for RYO than FM cigarette smokers. Puffing parameters show comparable reliability and validity for both groups of smokers and reveal some differences in smoking topography dependent on the type of cigarette smoked.
PREP advertisement features affect smokers’ beliefs regarding potential harm
Authors: Strasser A A , Tang K Z , Tuller M D , Cappella J N
Published: September 2008

Background:

The Institute of Medicine report on potential reduced exposure products (PREPs) recommends that advertising and labelling be regulated to prevent explicitly or implicitly false or misleading claims. Belief that a product is less harmful may increase use or prevent smoking cessation.

Objective:

To determine the effect of altering advertisement features on smokers’ beliefs of the harm exposure from a PREP.

Methods:

A Quest advertisement was digitally altered using computer software and presented to participants using web-based television recruitment contracted through a survey company. 500 current smokers completed demographic and smoking history questions, were randomised to view one of three advertisement conditions, then completed eight items assessing their beliefs of the harmfulness of the product. Advertisement conditions included the original, unaltered advertisement; a “red” condition where the cigarette packages were digitally altered to the colour red, implying increased harm potential; and a “no text” condition where all text was removed to reduce explicit product information. Polytomous logistic regression, using “incorrect,” “unsure” and “correct” as outcomes, and advertisement type and covariates as predictors, was used for analyses.

Results:

Participants randomised to the “no text” advertisement were less likely to be incorrect in their beliefs that Quest cigarettes are lower in tar, less addictive, less likely to cause cancer, have fewer chemicals, are healthier and make smoking safer.

Conclusions:

Smokers can form false beliefs about the harmfulness of PREP products based on how the PREPs are marketed. Careful examination must be undertaken to provide empirical evidence to better formulate regulatory principles of PREP advertising.
Effect of charcoal-containing cigarette filters on gas phase volatile organic compounds in mainstream cigarette smoke
Authors: Polzin G M , Zhang L , Hearn B A , Tavakoli A D , Vaughan C , Ding Y S , Ashley D L , Watson C H
Published: September 2008

Of the chemicals identified to date in mainstream cigarette smoke with known toxicological properties, the volatile organic compounds (VOCs) are considered the most hazardous group owing to their high abundance and toxicity. In this research we evaluate a recently introduced line of cigarettes that contain charcoal in their filters. The amount of charcoal in these filters ranged from 45 mg to 180 mg and were either dispersed among the filter material or contained in a small cavity in the filter segment. Charcoal has long been used for removing VOCs from both water and air. Our findings indicate that these cigarettes reduce machine generated mainstream smoke deliveries of a wide range of VOCs compared to a similar, non-charcoal filtered, cigarette. However, this reduction is dependent not only on the amount of charcoal present but also on the volume of smoke being drawn through the filter. While a brand with 45 mg charcoal reduces VOC delivery under ISO smoking conditions, charcoal saturation and breakthrough occur under more intense smoking conditions. Breakthrough is minimised for brands with the most charcoal. Overall, the brands with the most charcoal are effective at reducing VOC deliveries under even intense smoking conditions.
Tobacco flakes on cigarette filters grow bacteria: a potential health risk to the smoker?: Figure 1
Authors: Pauly J L , Waight J D , Paszkiewicz G M
Published: September 2008

Bacterial growth from a single flake of tobacco was documented for cigarettes that had been purchased recently from local vendors and from cigarettes that had been stored for more than six years in a warehouse. In a novel tobacco flake assay, a pack of cigarettes was opened within the sterile environment of a laminar flow hood. A single flake of tobacco was collected randomly and aseptically from the middle of the cigarette column and placed onto the surface of a blood agar plate. The test cigarettes included eight different popular US brands, and these were from three different tobacco companies. After 24 hours of incubation at 37°C, the plates showed bacterial growth for tobacco from all brands of cigarettes. Further, more than 90% of the individual tobacco flakes of a given brand grew bacteria. Likewise, bacteria grew from microparticulate tobacco that had been sieved from cigarettes. Tobacco flakes were observed lying loosely on the cut surface of the filter of cigarettes in newly opened packs, and bacteria grew from cigarette filters that had been touched to the surface of a blood agar plate. In conclusion, the results of these studies predict that diverse microbes and microbial toxins are carried by tobacco microparticulates that are released from the cigarette during smoking, and carried into mainstream smoke that is sucked deep into the lung.
Existing technologies to reduce specific toxicant emissions in cigarette smoke
Authors: O’Connor R J , Hurley P J
Published: September 2008

Background:

The World Health Organization Tobacco Product Regulation (TobReg) study group has proposed emissions level performance standards for nine toxicants (NNN, NNK, acetaldehyde, acrolein, 1,3-butadiene, CO, BaP, benzene and formaldehyde, all expressed as micrograms per milligram nicotine as measured under the Canadian intensive method) in cigarette smoke for parties to the FCTC in conjunction with regular monitoring of emissions of nine other toxicants of interest, nicotine and nicotine-free dry particulate matter (NFDPM, or “tar”).

Methods:

We examined the published literature and publicly available tobacco industry documents to determine the extent to which existing available technologies can be applied to reduce the emissions of the specified toxicants in cigarette smoke.

Results:

Agricultural practices (for example, fertilisers, curing), plant characteristics (for example, protein content, nicotine content), tobacco blending (for example, American blend vs Virginia blend) and cigarette design (for example, additives, filters, paper) issues all have roles in the generation and reduction of specific smoke toxicants. The tobacco industry has explored a number of technologies, including selective filtration, changes to curing practices and rod additives to reduce specific toxicants.

Conclusions:

Technologies exist to reduce the toxicants identified by TobReg. The extent to which the industry is able to simultaneously reduce toxicants, however, is unknown.
Spectrofluorometric method for measuring tobacco smoke particulate matter on cigarette filters and Cambridge pads
Authors: Paszkiewicz G M , Pauly J L
Published: September 2008

Almost all cigarettes sold have a filter (United States, >98%; worldwide, >95%). In the last 25 years cigarette manufacturers have introduced diverse filters designed to reduce components in tobacco smoke. Today, there exists a need to establish assays to assess the efficacy of cigarette filters to retain total particulate matter (TPM), particularly unique filters of cigarettes that are being marketed as potential reduced exposure products (PREPs). We report the results of studies that were undertaken to test the hypothesis that a technique could be established for dissolving cigarette filters, and that the TPM in the fluid could be quantified by spectrofluorometry. Described here are procedures for assaying TPM on both Cambridge filter pads (glass fibres) of smoking machines and on cigarette filters (cellulose acetate fibres). The principle of the assays is based upon the observation that there exists a direct correlation between the amount of tobacco product emission TPM and fluorescence. In the absence of a tobacco tar or TPM standard, the fluorescent dye acridine orange was confirmed as a useful surrogate. Filters assayed included those of Kentucky reference cigarettes 2R4F and popular US brand cigarettes. The proposed assays are inexpensive, expedient, reproducible and amendable for large-scale studies.
BESSIS–MOUSSA–VILLANI CONJECTURE AND GENERALIZED GAUSSIAN RANDOM VARIABLES
Authors: BOŻEJKO MAREK
Published: September 2008

In this paper we give the solution of Bessis–Moussa–Villani (BMV) conjecture for the generalized Gaussian random variables [Formula: see text] where f is in the real Hilbert space [Formula: see text].

The main examples of generalized Gaussian random variables are q-Gaussian random variables, (-1 ≤ q ≤ 1), related to q-CCR relation and other commutation relations. We will prove that BMV conjecture is true for all operators A = G(f), B = G(g); i.e. we will show that the function [Formula: see text] is positive-definite function on the real line. The case q = 0, i.e. when G(f) are the free Gaussian (Wigner) random variables and the operators A and B are free with respect to the vacuum trace was proved by Fannes and Petz.23
ON PERTURBED POSITIVE SEMIGROUPS ON THE BANACH SPACE OF TRACE CLASS OPERATORS
Authors: MOKHTAR-KHARROUBI MUSTAPHA
Published: September 2008

Let [Formula: see text] be the generator of a positive (i.e. leaving invariant [Formula: see text]) contraction semigroup on [Formula: see text], the space of self-adjoint trace class operators on a Hilbert space H, endowed with the trace norm, and let [Formula: see text] be a positive linear operator such that [Formula: see text], [Formula: see text]. We show that there exists a minimal positive contraction semigroup generated by some [Formula: see text] and provide a systematic study of the total mass carried by individual trajectories [Formula: see text] with non-negative initial data ρ. The analysis relies on mathematical properties of two (a priori) different extensions [Formula: see text] of the functional [Formula: see text] to [Formula: see text].
NONCOMMUTATIVE BROWNIAN MOTIONS ASSOCIATED WITH KESTEN DISTRIBUTIONS AND RELATED POISSON PROCESSES
Authors: LENCZEWSKI ROMUALD , SAŁAPATA RAFAŁ
Published: September 2008

We introduce and study a noncommutative two-parameter family of noncommutative Brownian motions in the free Fock space. They are associated with Kesten laws and give a continuous interpolation between Brownian motions in free probability and monotone probability. The combinatorics of our model is based on ordered non-crossing partitions, in which to each such partition P we assign the weight w(P) = pe(P)qe'(P), where e(P) and e'(P) are, respectively, the numbers of disorders and orders in P related to the natural partial order on the set of blocks of P implemented by the relation of being inner or outer. In particular, we obtain a simple relation between Delaney's numbers (related to inner blocks in non-crossing partitions) and generalized Euler's numbers (related to orders and disorders in ordered non-crossing partitions). An important feature of our interpolation is that the mixed moments of the corresponding creation and annihilation processes also reproduce their monotone and free counterparts, which does not take place in other interpolations. The same combinatorics is used to construct an interpolation between free and monotone Poisson processes.
INFINITE TENSOR PRODUCTS OF SPATIAL PRODUCT SYSTEMS
Authors: FLORICEL REMUS
Published: September 2008

The aim of this work is to define the infinite tensor product [Formula: see text] of a countable family {Ei}i ∈ 𝕀 of spatial product systems with respect to a family [Formula: see text] of normalized units, and to analyze the main properties of this construction. Among other things, we show that [Formula: see text] is an amenable product system, respectively a product system of type I, provided that every product system Ei is amenable, respectively of type I.
UNITARY REPRESENTATIONS OF THE WITT AND sl(2, ℝ)-ALGEBRAS THROUGH RENORMALIZED POWERS OF THE QUANTUM PASCAL WHITE NOISE
Authors: BARHOUMI ABDESSATAR , OUERDIANE HABIB , RIAHI ANIS
Published: September 2008

By using an appropriate space of distributions, [Formula: see text], we derive the chaos decomposition property of the Hilbert space of quadratic integrable functionals with respect to the Pascal white noise measure ΛNB. The constructed decomposition is used to define a nuclear triple [Formula: see text] of test and generalized functions, where θ is a Young function satisfying some suitable conditions. A general characterization theorems are proven for the Pascal white noise distributions, white noise test functions and white noise operators in terms of analytical functions with growth condition of exponential type. By using appropriate renormalization procedure, we obtain the representation of the square of white noise obtained by Accardi–Franz–Skeide in Ref. 5. Finally, we investigate the main aim of this paper which is to give unitary equivalent representations of the Witt algebra in the basis of Pascal white noise theory.
ON PARTITIONED DIFFERENTIAL QUASIFIELDS
Authors: KEIGHER WILLIAM F. , PRITCHARD F. LEON
Published: September 2008

A differential quasifield is a natural generalization of a differential field in characteristic p > 0. Elementary properties of differential quasifields are considered, and a generalized version of the theorem on the connection between linear independence over constants and the wronskian is presented. The notion of a partitioned differential quasifield is introduced, and the behavior of partitioned differential quasifields is considered, including under an extension of scalars.
THE UNIVERSAL COVER OF A MONOMIAL TRIANGULAR ALGEBRA WITHOUT MULTIPLE ARROWS
Authors: LE MEUR PATRICK
Published: September 2008

Let A be a basic connected finite dimensional algebra over an algebraically closed field k. Assuming that A is monomial and that the ordinary quiver Q of A has no oriented cycle and no multiple arrows, we prove that A admits a universal cover with group the fundamental group of the underlying space of Q.
SIMPLE JORDAN CONFORMAL SUPERALGEBRAS
Authors: KAC VICTOR G. , RETAKH ALEXANDER
Published: September 2008

We classify simple finite Jordan conformal superalgebras and also establish preliminary results for the classification of simple finite Jordan pseudoalgebras.
THE BOUND QUIVER OF A SPLIT EXTENSION
Authors: ASSEM IBRAHIM , COELHO FLÁVIO U. , TREPODE SONIA
Published: September 2008

In this paper, we give a sufficient (which is also necessary under a compatibility hypothesis) condition on a set of arrows in the quiver of an algebra A so that A is a split extension of A/M, where M is the ideal of A generated by the classes of these arrows. We also compare the notion of split extension with that of semiconvex extension of algebras.
GORENSTEIN FP-INJECTIVE AND GORENSTEIN FLAT MODULES
Authors: MAO LIXIN , DING NANQING
Published: September 2008

In this paper, Gorenstein FP-injective modules are introduced and studied. An R-module M is called Gorenstein FP-injective if there is an exact sequence ⋯ → E1 → E0 → E0 → E1 → ⋯ of injective R-modules with M = ker (E0 → E1) and such that Hom (E, -) leaves the sequence exact whenever E is an FP-injective R-module. Some properties of Gorenstein FP-injective and Gorenstein flat modules over coherent rings are obtained. Several known results are extended.
Stratocladistics: Integrating Temporal Data and Character Data in Phylogenetic Inference
Authors: Fisher Daniel C.
Published: September 2008

Debate has long simmered over whether data on the order of appearance of taxa in the stratigraphic record should play any role in analyses of phylogenetic relationships among those taxa. Critics argue that temporal data are in principle inapplicable to questions of cladistic relationship, but specific versions of this claim all seem flawed. Stratocladistics offers a methodological context (patterned after that of cladistics itself) within which temporal data participate along with conventional character data in selecting most-parsimonious hypotheses. Stratocladistics outperforms cladistics in tests based on simulated histories, and additional testing will be facilitated by new software automating stratocladistic searches. As with any body of data, we may decide to include or exclude temporal data for specific reasons, but the explanatory power of hypotheses that use both temporal and conventional character data exceeds that of hypotheses based on character data alone.
Bionomics of Bagworms (Lepidoptera: Psychidae)
Authors: Rhainds Marc , Davis Donald R. , Price Peter W.
Published: September 2008

The bagworm family (Lepidoptera: Psychidae) includes approximately 1000 species, all of which complete larval development within a self-enclosing bag. The family is remarkable in that female aptery occurs in over half of the known species and within 9 of the 10 currently recognized subfamilies. In the more derived subfamilies, several life-history traits are associated with eruptive population dynamics, e.g., neoteny of females, high fecundity, dispersal on silken threads, and high level of polyphagy. Other salient features shared by many species include a short embryonic period, developmental synchrony, sexual segregation of pupation sites, short longevity of adults, male-biased sex ratio, sexual dimorphism, protogyny, parthenogenesis, and oviposition in the pupal case. The unusual mating behavior of bagworms, characterized by an earlier emergence of females than males and a high proportion of females that do not mate as adults, challenges conventional wisdom regarding the evolution of mating systems.
The Role of Aminoacyl-tRNA Synthetases in Genetic Diseases
Authors: Antonellis Anthony , Green Eric D.
Published: September 2008

Aminoacyl-tRNA synthetases (ARSs) are ubiquitously expressed, essential enzymes responsible for performing the first step of protein synthesis. Specifically, ARSs attach amino acids to their cognate tRNA molecules in the cytoplasm and mitochondria. Recent studies have demonstrated that mutations in genes encoding ARSs can result in neurodegeneration, raising many questions about the role of these enzymes (and protein synthesis in general) in neuronal function. In this review, we summarize the current knowledge of genetic diseases that are associated with mutations in ARS-encoding genes, discuss the potential pathogenic mechanisms underlying these disorders, and point to likely areas of future research that will advance our understanding about the role of ARSs in genetic diseases.
The Current Landscape for Direct-to-Consumer Genetic Testing: Legal, Ethical, and Policy Issues
Authors: Hogarth Stuart , Javitt Gail , Melzer David
Published: September 2008

This review surveys the developing market for direct-to-consumer (DTC) genetic tests and examines the range of companies and tests available, the regulatory landscape, the concerns raised about DTC testing, and the calls for enhanced oversight. We provide a comparative overview of the situation, particularly in the United States and Europe, by exploring the regulatory frameworks for medical devices and clinical laboratories. We also discuss a variety of other mechanisms such as general controls on advertising and consumer law mechanisms.
PTEN and the PI3-Kinase Pathway in Cancer
Authors: Chalhoub Nader , Baker Suzanne J.
Published: September 2008

PI3-kinase and PTEN are major positive and negative regulators, respectively, of the PI3-kinase pathway, which regulates growth, survival, and proliferation. These key signaling components are two of the most frequently mutated proteins in human cancers, resulting in unregulated activation of PI3K signaling and providing irrefutable genetic evidence of the central role of this pathway in tumorigenesis. PTEN regulates PI3K signaling by dephosphorylating the lipid signaling intermediate PIP3, but PTEN may have additional phosphatase-independent activities, as well as other functions in the nucleus. In this review, we highlight current work showing cancer-relevant complexities in the regulation of PTEN and PI3K activity, potential novel functions for PTEN, and feedback regulation within the pathway. The significance and complexity of PI3K signaling make it an important but challenging therapeutic target for cancer.
Concepts and Categories: A Cognitive Neuropsychological Perspective
Authors: Mahon Bradford Z. , Caramazza Alfonso
Published: September 2008

One of the most provocative and exciting issues in cognitive science is how neural specificity for semantic categories of common objects arises in the functional architecture of the brain. More than two decades of research on the neuropsychological phenomenon of category-specific semantic deficits has generated detailed claims about the organization and representation of conceptual knowledge. More recently, researchers have sought to test hypotheses developed on the basis of neuropsychological evidence with functional imaging. From those two fields, the empirical generalization emerges that object domain and sensory modality jointly constrain the organization of knowledge in the brain. At the same time, research within the embodied cognition framework has highlighted the need to articulate how information is communicated between the sensory and motor systems, and processes that represent and generalize abstract information. Those developments point toward a new approach for understanding category specificity in terms of the coordinated influences of diverse regions and cognitive systems.
Metabolic flexibility and insulin resistance
Authors: Galgani Jose E. , Moro Cedric , Ravussin Eric
Published: September 2008

Metabolic flexibility is the capacity for the organism to adapt fuel oxidation to fuel availability. The inability to modify fuel oxidation in response to changes in nutrient availability has been implicated in the accumulation of intramyocellular lipid and insulin resistance. The metabolic flexibility assessed by the ability to switch from fat to carbohydrate oxidation is usually impaired during a hyperinsulinemic clamp in insulin-resistant subjects; however, this “metabolic inflexibility” is mostly the consequence of impaired cellular glucose uptake. Indeed, after controlling for insulin-stimulated glucose disposal rate (amount of glucose available for oxidation), metabolic flexibility is not altered in obesity regardless of the presence of type 2 diabetes. To understand how intramyocellular lipids accumulate and cause insulin resistance, the assessment of metabolic flexibility to high-fat diets is more relevant than metabolic flexibility during a hyperinsulinemic clamp. An impaired capacity to upregulate muscle lipid oxidation in the face of high lipid supply may lead to increased muscle fat accumulation and insulin resistance. Surprisingly, very few studies have investigated the response to high-fat diets. In this review, we discuss the role of glucose disposal rate, adipose tissue lipid storage, and mitochondrial function on metabolic flexibility. Additionally, we emphasize the bias of using the change in respiratory quotient to calculate metabolic flexibility and propose novel approaches to assess metabolic flexibility. On the basis of current evidence, one cannot conclude that impaired metabolic flexibility is responsible for the accumulation of intramyocellular lipid and insulin resistance. We propose to study metabolic flexibility in response to high-fat diets in individuals having contrasting degree of insulin sensitivity and/or mitochondrial characteristics.
In vivo measurement of synthesis rate of individual skeletal muscle mitochondrial proteins
Authors: Jaleel Abdul , Short Kevin R. , Asmann Yan W. , Klaus Katherine A. , Morse Dawn M. , Ford G. Charles , Nair K. Sreekumaran
Published: September 2008

Skeletal muscle mitochondrial dysfunction occurs in many conditions including aging and insulin resistance, but the molecular pathways of the mitochondrial dysfunction remain unclear. Presently, no methodologies are available to measure synthesis rates of individual mitochondrial proteins, which limits our ability to fully understand the translational regulation of gene transcripts. Here, we report a methodology to measure synthesis rates of multiple muscle mitochondrial proteins, which, along with large-scale measurements of mitochondrial gene transcripts and protein concentrations, will enable us to determine whether mitochondrial alteration is due to transcriptional or translational changes. The methodology involves in vivo labeling of muscle proteins with l-[ ring-13C6]phenylalanine, protein purification by two-dimensional gel electrophoresis of muscle mitochondrial fraction, and protein identification and stable isotope abundance measurements by tandem mass spectrometry. Synthesis rates of 68 mitochondrial and 23 nonmitochondrial proteins from skeletal muscle mitochondrial fraction showed a 10-fold range, with the lowest rate for a structural protein such as myosin heavy chain (0.16 ± 0.04%/h) and the highest for a mitochondrial protein such as dihydrolipoamide branched chain transacylase E2 (1.5 ± 0.42%/h). This method offers an opportunity to better define the translational regulation of proteins in skeletal muscle or other tissues.
Increased superoxide levels in ganglia and sympathoexcitation are involved in sarafotoxin 6c-induced hypertension
Authors: Li Melissa , Dai Xiaoling , Watts Stephanie , Kreulen David , Fink Gregory
Published: September 2008

Endothelin (ET) type B receptors (ETBR) are expressed in multiple tissues and perform different functions depending on their location. ETBR mediate endothelium-dependent vasodilation, clearance of circulating ET, and diuretic effects; all of these should produce a fall in arterial blood pressure. However, we recently showed that chronic activation of ETBR in rats with the selective agonist sarafotoxin 6c (S6c) causes sustained hypertension. We have proposed that one mechanism of this effect is constriction of capacitance vessels. The current study was performed to determine whether S6c hypertension is caused by increased generation of reactive oxygen species (ROS) and/or activation of the sympathetic nervous system. The model used was continuous 5-day infusion of S6c into male Sprague-Dawley rats. No changes in superoxide anion levels in arteries and veins were found in hypertensive S6c-treated rats. However, superoxide levels were increased in sympathetic ganglia from S6c-treated rats. In addition, superoxide levels in ganglia increased progressively the longer the animals received S6c. Treatment with the antioxidant tempol impaired S6c-induced hypertension and decreased superoxide levels in ganglia. Acute ganglion blockade lowered blood pressure more in S6c-treated rats than in vehicle-treated rats. Although plasma norepinephrine levels were not increased in S6c hypertension, surgical ablation of the celiac ganglion plexus, which provides most of the sympathetic innervation to the splanchnic organs, significantly attenuated hypertension development. The results suggest that S6c-induced hypertension is partially mediated by sympathoexcitation to the splanchnic organs driven by increased oxidative stress in prevertebral sympathetic ganglia.
Cerebral hypoperfusion during hypoxic exercise following two different hypoxic exposures: independence from changes in dynamic autoregulation and reactivity
Authors: Ainslie Philip N. , Hamlin Michael , Hellemans John , Rasmussen Peter , Ogoh Shigehiko
Published: September 2008

We examined the effects of exposure to 10–12 days intermittent hypercapnia [IHC: 5:5-min hypercapnia (inspired fraction of CO2 0.05)-to-normoxia for 90 min ( n = 10)], intermittent hypoxia [IH: 5:5-min hypoxia-to-normoxia for 90 min ( n = 11)] or 12 days of continuous hypoxia [CH: 1,560 m ( n = 7)], or both IH followed by CH on cardiorespiratory and cerebrovascular function during steady-state cycling exercise with and without hypoxia (inspired fraction of oxygen, 0.14). Cerebrovascular reactivity to CO2 was also monitored. During all procedures, ventilation, end-tidal gases, blood pressure, muscle and cerebral oxygenation (near-infrared spectroscopy), and middle cerebral artery blood flow velocity (MCAv) were measured continuously. Dynamic cerebral autoregulation (CA) was assessed using transfer-function analysis. Hypoxic exercise resulted in increases in ventilation, hypocapnia, heart rate, and cardiac output when compared with normoxic exercise ( P < 0.05); these responses were unchanged following IHC but were elevated following the IH and CH exposure ( P < 0.05) with no between-intervention differences. Following IH and/or CH exposure, the greater hypocapnia during hypoxic exercise provoked a decrease in MCAv ( P < 0.05 vs. preexposure) that was related to lowered cerebral oxygenation ( r = 0.54; P < 0.05). Following any intervention, during hypoxic exercise, the apparent impairment in CA, reflected in lowered low-frequency phase between MCAv and BP, and MCAv-CO2 reactivity, were unaltered. Conversely, during hypoxic exercise following both IH and/or CH, there was less of a decrease in muscle oxygenation ( P < 0.05 vs. preexposure). Thus IH or CH induces some adaptation at the muscle level and lowers MCAv and cerebral oxygenation during hypoxic exercise, potentially mediated by the greater hypocapnia, rather than a compromise in CA or MCAv reactivity.