bluuebunny/crossref_metadata_2025 huggingface dataset:
NrrA Directly Regulates Expression of
hetR
during Heterocyst Differentiation in the Cyanobacterium
Anabaena
sp. Strain PCC 7120
Authors: Ehira Shigeki , Ohmori Masayuki
Published: December 2006

Heterocyst differentiation in the cyanobacterium
Anabaena
sp. strain PCC 7120 requires NtcA, the global nitrogen regulator in cyanobacteria, and HetR, the master regulator of heterocyst differentiation. Expression of
hetR
is upregulated by nitrogen deprivation, and its upregulation depends on NtcA. However, it has not yet been revealed how NtcA regulates the expression of
hetR
. In the experiments presented here, it was confirmed that NrrA (All4312), a nitrogen-responsive response regulator, was required for the upregulation of
hetR
. The use of the nitrogen-responsive transcription initiation sites (TISs) for the
hetR
gene depended upon NrrA. NrrA bound specifically to the region upstream of TISs located at positions −728 and −696 in vitro. Overexpression of
nrrA
resulted in enhanced
hetR
expression and heterocyst formation. A molecular regulatory cascade is proposed whereby NtcA upregulates the expression of
nrrA
upon limitation of combined nitrogen in the medium and then NrrA upregulates the expression of
hetR
, leading to heterocyst differentiation.
Mutation in a “
tesB
-Like” Hydroxyacyl-Coenzyme A-Specific Thioesterase Gene Causes Hyperproduction of Extracellular Polyhydroxyalkanoates by
Alcanivorax borkumensis
SK2
Authors: Sabirova Julia S. , Ferrer Manuel , Lünsdorf Heinrich , Wray Victor , Kalscheuer Rainer , Steinbüchel Alexander , Timmis Kenneth N. , Golyshin Peter N.
Published: December 2006

A novel mutant of the marine oil-degrading bacterium
Alcanivorax borkumensis
SK2, containing a mini-Tn
5
transposon disrupting a “
tesB
-like” acyl-coenzyme A (CoA) thioesterase gene, was found to hyperproduce polyhydroxyalkanoates (PHA), resulting in the extracellular deposition of this biotechnologically important polymer when grown on alkanes. The
tesB
-like gene encodes a distinct novel enzyme activity, which acts exclusively on hydroxylated acyl-CoAs and thus represents a hydroxyacyl-CoA-specific thioesterase. Inactivation of this enzyme results in the rechanneling of CoA-activated hydroxylated fatty acids, the cellular intermediates of alkane degradation, towards PHA production. These findings may open up new avenues for the development of simplified biotechnological processes for the production of PHA as a raw material for the production of bioplastics.
Transcriptomic Analysis Reveals a Bifurcated Terephthalate Degradation Pathway in
Rhodococcus
sp. Strain RHA1
Authors: Hara Hirofumi , Eltis Lindsay D. , Davies Julian E. , Mohn William W.
Published: December 2006

Phthalate isomers and their esters are important pollutants whose biodegradation is not well understood.
Rhodococcus
sp. strain RHA1 is notable for its ability to degrade a wide range of aromatic compounds. RHA1 was previously shown to degrade phthalate (PTH) and to have genes putatively encoding terephthalate (TPA) degradation. Transcriptomic analysis of 8,213 genes indicated that 150 were up-regulated during growth on PTH and that 521 were up-regulated during growth on TPA. Distinct ring cleavage dioxygenase systems were differentially expressed during growth on PTH and TPA. Genes encoding the protocatechuate (PCA) pathway were induced on both substrates, while genes encoding the catechol branch of the PCA pathway were additionally induced only on TPA. Accordingly, protocatechuate-3,4-dioxygenase activity was induced in cells grown on both substrates, while catechol-1,2-dioxygenase activity was induced only in cells grown on TPA. Knockout analysis indicated that
pcaL
, encoding 3-oxoadipate enol-lactone hydrolase and 4-carboxymuconolactone decarboxylase, was required for growth on both substrates but that
pcaB
, encoding β-carboxy-
cis
,
cis
-muconate lactonizing enzyme, was required for growth on PTH only. These results indicate that PTH is degraded solely via the PCA pathway, whereas TPA is degraded via a bifurcated pathway that additionally includes the catechol branch of the PCA pathway.
nalD
Encodes a Second Repressor of the
mexAB-oprM
Multidrug Efflux Operon of
Pseudomonas aeruginosa
Authors: Morita Yuji , Cao Lily , Gould Virginia C. , Avison Matthew B. , Poole Keith
Published: December 2006

The
Pseudomonas aeruginosa nalD
gene encodes a TetR family repressor with homology to the SmeT and TtgR repressors of the
smeDEF
and
ttgABC
multidrug efflux systems of
Stenotrophomonas maltophilia
and
Pseudomonas putida
, respectively. A sequence upstream of
mexAB-oprM
and overlapping a second promoter for this efflux system was very similar to the SmeT and TtgR operator sequences, and NalD binding to this region was, in fact, demonstrated. Moreover, increased expression from this promoter was seen in a
nalD
mutant, consistent with NalD directly controlling
mexAB-oprM
expression from a second promoter.
Analysis of Proline Reduction in the Nosocomial Pathogen
Clostridium difficile
Authors: Jackson Sarah , Calos Mary , Myers Andrew , Self William T.
Published: December 2006

Clostridium difficile
, a proteolytic strict anaerobe, has emerged as a clinically significant nosocomial pathogen in recent years. Pathogenesis is due to the production of lethal toxins, A and B, members of the large clostridial cytotoxin family. Although it has been established that alterations in the amino acid content of the growth medium affect toxin production, the molecular mechanism for this observed effect is not yet known. Since there is a paucity of information on the amino acid fermentation pathways used by this pathogen, we investigated whether Stickland reactions might be at the heart of its bioenergetic pathways. Growth of
C. difficile
on Stickland pairs yielded large increases in cell density in a limiting basal medium, demonstrating that these reactions are tied to ATP production. Selenium supplementation was required for this increase in cell yield. Analysis of genome sequence data reveals genes encoding the protein components of two key selenoenzyme reductases, glycine reductase and
d
-proline reductase (PR). These selenoenzymes were expressed upon the addition of the corresponding Stickland acceptor (glycine, proline, or hydroxyproline). Purification of the selenoenzyme
d
-proline reductase revealed a mixed complex of PrdA and PrdB (SeCys-containing) proteins. PR utilized only
d
-proline but not
l
-hydroxyproline, even in the presence of an expressed and purified proline racemase. PR was found to be independent of divalent cations, and zinc was a potent inhibitor of PR. These results show that Stickland reactions are key to the growth of
C. difficile
and that the mechanism of PR may differ significantly from that of previously studied PR from nonpathogenic species.
RhlR Expression inPseudomonas aeruginosaIs Modulated by thePseudomonasQuinolone Signal via PhoB-Dependent and -Independent Pathways
Authors: Jensen Vanessa , Löns Dagmar , Zaoui Caroline , Bredenbruch Florian , Meissner Andree , Dieterich Guido , Münch Richard , Häussler Susanne
Published: December 2006

The expression of virulence determinants inPseudomonas aeruginosais coordinately regulated in response to both the social environment—commonly referred to as quorum sensing—and to environmental cues. In this study we have dissected the various independent regulation levels for pyocyanin production, which is influenced by the homoserine lactone- andPseudomonasquinolone signal (PQS)-mediated quorum-sensing systems as well as by iron and phosphate availability. We demonstrate that the phosphate regulon is involved in the transcriptional activation ofrhlRand the augmentation of PQS and pyocyanin production under phosphate limitation. However, we also observed an enhancement ofrhlRtranscription under low-iron medium conditions and after the addition of PQS that was independent of the phosphate regulon. These results highlight the complexity of secondary metabolite production inP. aeruginosavia environmental cues and the quorum-sensing system.
Similarity and Differences in the
Lactobacillus acidophilus
Group Identified by Polyphasic Analysis and Comparative Genomics
Authors: Berger Bernard , Pridmore R. David , Barretto Caroline , Delmas-Julien Françoise , Schreiber Kerstin , Arigoni Fabrizio , Brüssow Harald
Published: December 2006

A set of lactobacilli were investigated by polyphasic analysis. Multilocus sequence analysis, DNA typing, microarray analysis, and in silico whole-genome alignments provided a remarkably consistent pattern of similarity within the
Lactobacillus acidophilus
complex. On microarray analysis, 17 and 5% of the genes from
Lactobacillus johnsonii
strain NCC533 represented variable and strain-specific genes, respectively, when tested against four independent isolates of
L. johnsonii
. When projected on the NCC533 genome map, about 10 large clusters of variable genes were identified, and they were enriched around the terminus of replication. A quarter of the variable genes and two-thirds of the strain-specific genes were associated with mobile DNA. Signatures for horizontal gene transfer and modular evolution were found in prophages and in DNA from the exopolysaccharide biosynthesis cluster. On microarray hybridizations,
Lactobacillus gasseri
strains showed a shift to significantly lower fluorescence intensities than the
L. johnsonii
test strains, and only genes encoding very conserved cellular functions from
L. acidophilus
hybridized to the
L. johnsonii
array. In-silico comparative genomics showed extensive protein sequence similarity and genome synteny of
L. johnsonii
with
L. gasseri
,
L. acidophilus
, and
Lactobacillus delbrueckii
; moderate synteny with
Lactobacillus casei
; and scattered X-type sharing of protein sequence identity with the other sequenced lactobacilli. The observation of a stepwise decrease in similarity between the members of the
L. acidophilus
group suggests a strong element of vertical evolution in a natural phylogenetic group. Modern whole-genome-based techniques are thus a useful adjunct to the clarification of taxonomical relationships in problematic bacterial groups.
Genetic Evidence Suggests that the Intergenic Region between
pstA
and
pstB
Plays a Role in the Regulation of
rpoS
Translation during Phosphate Limitation
Authors: Schurdell Michael S. , Woodbury Garrett M. , McCleary William R.
Published: December 2006

In addition to the Pho regulon, phosphate starvation also stimulates the accumulation of RpoS. Several deletion mutations within the
pstSCAB-phoU
operon were tested for the accumulation of RpoS during exponential growth. Our data suggest that the processed 3′ end of the
pstA
message stimulates translation of
rpoS
.
Does the Importance of the C-Terminal Residues in the Maturation of RgpB from
Porphyromonas gingivalis
Reveal a Novel Mechanism for Protein Export in a Subgroup of Gram-Negative Bacteria?
Authors: Nguyen Ky-Anh , Travis James , Potempa Jan
Published: December 2006

The mature 507-residue RgpB protein belongs to an important class of extracellular outer membrane-associated proteases, the gingipains, from the oral pathogen
Porphyromonas gingivalis
that has been shown to play a central role in the virulence of the organism. The C termini of these gingipains along with other outer membrane proteins from the organism share homologous sequences and have been suggested to function in attachment of these proteins to the outer membrane. In this report, we have created a series of truncated and site-directed mutants of the C terminus from a representative member of this class, the RgpB protease, to investigate its role in the maturation of these proteins. Truncation of the last two residues (valyl-lysine) from the C terminus is sufficient to create an inactive version of the protein that lacks the posttranslational glycosylation seen in the wild type, and the protein remains trapped behind the outer membrane. Alanine scanning of the last five residues revealed the importance of the C-terminal motif in mediating correct posttranslational modification of the protein. This result may have a wider implication in a novel secretory pathway in distinct members of the
Cytophaga-Flavobacterium-Bacteroidetes
phylum.
Interaction of GapA with HPr and Its Homologue, Crh: Novel Levels of Regulation of a Key Step of Glycolysis inBacillus subtilis?
Authors: Pompeo Frédérique , Luciano Jennifer , Galinier Anne
Published: December 2006

InBacillus subtiliscells, we identified a new partner of HPr, an enzyme of the glycolysis pathway, the glyceraldehyde-3-phosphate dehydrogenase GapA. We showed that, in vitro, phosphorylated and unphosphorylated forms of HPr and its homologue, Crh, could interact with GapA, but only their seryl-phosphorylated forms were able to inhibit its activity.
Chloroplast SecA and
Escherichia coli
SecA Have Distinct Lipid and Signal Peptide Preferences
Authors: Sun Changqi , Rusch Sharyn L. , Kim Jinoh , Kendall Debra A.
Published: December 2006

Like prokaryotic Sec-dependent protein transport, chloroplasts utilize SecA. However, we observe distinctive requirements for the stimulation of chloroplast SecA ATPase activity; it is optimally stimulated in the presence of galactolipid and only a small fraction of anionic lipid and by Sec-dependent thylakoid signal peptides but not
Escherichia coli
signal peptides.
Patient confidentiality and telephone consultations: time for a password
Authors: Sokol D K , Car J
Published: December 2006

Although telephone consultations are widely used in the delivery of healthcare, they are vulnerable to breaches of patient confidentiality. Current guidelines on telephone consultations do not address adequately the issue of confidentiality. In this paper, we propose a solution to the problem: a password system to control access to patient information. Authorised persons will be offered the option of selecting a password which they will use to validate their request for information over the telephone. This simple yet stringent method of access control should improve security while allowing the continuing evolution of telephone consultations.
Conflicts of interest in divisions of general practice
Authors: Palmer N , Braunack-Mayer A , Rogers W , Provis C , Cullity G
Published: December 2006

Community-based healthcare organisations manage competing, and often conflicting, priorities. These conflicts can arise from the multiple roles these organisations take up, and from the diverse range of stakeholders to whom they must be responsive. Often such conflicts may be titled conflicts of interest; however, what precisely constitutes such conflicts and what should be done about them is not always clear. Clarity about the duties owed by organisations and the roles they assume can help identify and manage some of these conflicts. Taking divisions of general practice in Australia as an example, this paper sets out to distinguish two main types of conflicts of interest, so that they may be more clearly identified and more effectively managed.
Autopathography and humane medicine:The diving bell and the butterfly—an interpretation
Authors: Kearney P J
Published: December 2006

Autopathographies are an expanding genre of books and articles that are a potential resource for students interested in the medical humanities. New curricula emphasise the need to familiarise medical students with the patient’s point of view. Different specialities compete for the student’s attention and the medical humanities are not an exception. Some form of assessment is necessary to reflect the importance of the patient’s perspective. One way may be to request students analyse their chosen autopathography. The article presents an example based on one of the better know accounts. The identified themes reflect the sudden disruption in the author’s biography. The topics are connected to the medical disorder and illustrated by quotations. The different categories of autopathography can be helpful in understanding the author’s perspective. In this instance the author was a full time editor before his stroke. The style of the book employs professional distance from the narrative. This is more compatible with the description of metapathography rather than the original classification of autopathogrphies as religious, angry or alternative.
QUANTIFYING PERSISTENT BEHAVIOR IN EARTH'S APPARENT RESISTIVITY TIME SERIES
Authors: TELESCA LUCIANO , BALASCO MARIANNA , LAPENNA VINCENZO , ROMANO GERARDO , SINISCALCHI AGATA
Published: December 2006

The multiple segmenting method (MSM) has been applied to investigate the scaling behaviour in the Earth's apparent resistivity time series, measured in a seismic area of southern Italy. The study of apparent resistivity represents one of the most important scientific challenges in the studies devoted to the geophysical monitoring. Our results show that apparent resistivity is characterized by a persistent scaling behaviour at all the periods considered, with the scaling exponent tending approximately to 0.5.
Dynamic changes of cardiac conduction during rapid pacing
Authors: Kondratyev Aleksandar A. , Ponard Julien G. C. , Munteanu Adelina , Rohr Stephan , Kucera Jan P.
Published: December 2006

Slow conduction and unidirectional conduction block (UCB) are key mechanisms of reentry. Following abrupt changes in heart rate, dynamic changes of conduction velocity (CV) and structurally determined UCB may critically influence arrhythmogenesis. Using patterned cultures of neonatal rat ventricular myocytes grown on microelectrode arrays, we investigated the dynamics of CV in linear strands and the behavior of UCB in tissue expansions following an abrupt decrease in pacing cycle length (CL). Ionic mechanisms underlying rate-dependent conduction changes were investigated using the Pandit-Clark-Giles-Demir model. In linear strands, CV gradually decreased upon a reduction of CL from 500 ms to 230–300 ms. In contrast, at very short CLs (110–220 ms), CV first decreased before increasing again. The simulations suggested that the initial conduction slowing resulted from gradually increasing action potential duration (APD), decreasing diastolic intervals, and increasing postrepolarization refractoriness, which impaired Na+ current ( INa) recovery. Only at very short CLs did APD subsequently shorten again due to increasing Na+/K+ pump current secondary to intracellular Na+ accumulation, which caused recovery of CV. Across tissue expansions, the degree of UCB gradually increased at CLs of 250–390 ms, whereas at CLs of 180–240 ms, it first increased and subsequently decreased. In the simulations, reduction of inward currents caused by increasing intracellular Na+ and Ca2+ concentrations contributed to UCB progression, which was reversed by increasing Na+/K+ pump activity. In conclusion, CV and UCB follow intricate dynamics upon an abrupt decrease in CL that are determined by the interplay among INa recovery, postrepolarization refractoriness, APD changes, ion accumulation, and Na+/K+ pump function.
Increased expression of SERCA in the hearts of transgenic mice results in increased oxidation of glucose
Authors: Belke Darrell D. , Swanson Eric , Suarez Jorge , Scott Brian T. , Stenbit Antine E. , Dillmann Wolfgang H.
Published: December 2006

While several transgenic mouse models exhibit improved contractile characteristics in the heart, less is known about how these changes influence energy metabolism, specifically the balance between carbohydrate and fatty acid oxidation. In the present study we examine glucose and fatty acid oxidation in transgenic mice, generated to overexpress sarco(endo)plasmic reticulum calcium-ATPase (SERCA), which have an enhanced contractile phenotype. Energy substrate metabolism was measured in isolated working hearts using radiolabeled glucose and palmitate. We also examined oxygen consumption to see whether SERCA overexpression is associated with increased oxygen utilization. Since SERCA is important in calcium handling within the cardiac myocyte, we examined cytosolic calcium transients in isolated myocytes using indo-1, and mitochondrial calcium levels using pericam, an adenovirally expressed, mitochondrially targeted ratiometric calcium indicator. Oxygen consumption did not differ between wild-type and SERCA groups; however, we were able to show an increased utilization of glucose for oxidative metabolism and a corresponding decreased utilization of fatty acids in the SERCA group. Cytosolic calcium transients were increased in myocytes isolated from SERCA mice, and they show a faster rate of decay of the calcium transient. With these observations we noted increased levels of mitochondrial calcium in the SERCA group, which was associated with an increase in the active form of the pyruvate dehydrogenase complex. Since an increase in mitochondrial calcium levels leads to activation of the pyruvate dehydrogenase complex (the rate-limiting step for carbohydrate oxidation), the increased glucose utilization observed in isolated perfused hearts in the SERCA group may reflect a higher level of mitochondrial calcium.
Loss of ischemic preconditioning's cardioprotection in aged mouse hearts is associated with reduced gap junctional and mitochondrial levels of connexin 43
Authors: Boengler Kerstin , Konietzka Ina , Buechert Astrid , Heinen Yvonne , Garcia-Dorado David , Heusch Gerd , Schulz Rainer
Published: December 2006

Connexin 43 (Cx43) is localized at left ventricular (LV) gap junctions and in cardiomyocyte mitochondria. A genetically induced reduction of Cx43 as well as blockade of mitochondrial Cx43 import abolishes the infarct size (IS) reduction by ischemic preconditioning (IP). With progressing age, Cx43 content in ventricular and atrial tissue homogenates is reduced. We now investigated whether or not 1) the mitochondrial Cx43 content is reduced in aged mice hearts and 2) IS reduction by IP is lost in aged mice hearts in vivo. Confirming previous results, sarcolemmal Cx43 content was reduced in aged (>13 mo) compared with young (<3 mo) C57Bl/6 mice hearts, whereas the expression levels of protein kinase C ε and endothelial nitric oxide synthase remained unchanged. Also in mitochondria isolated from aged mice LV myocardium, Western blot analysis indicated a 40% decrease in Cx43 content compared with mitochondria isolated from young mice hearts. In young mice hearts, IP by one cycle of 10 min ischemia and 10 min reperfusion reduced IS (% of area at risk) following 30 min regional ischemia and 120 min reperfusion from 67.7 ± 3.3 ( n = 17) to 34.2 ± 6.6 ( n = 5, P < 0.05). In contrast, IP's cardioprotection was lost in aged mice hearts, since IS in nonpreconditioned (57.5 ± 4.0, n = 10) and preconditioned hearts (65.4 ± 6.3, n = 8, P = not significant) was not different. In conclusion, mitochondrial Cx43 content is decreased in aged mouse hearts. The reduced levels of Cx43 may contribute to the age-related loss of cardioprotection by IP.
Molecular and functional properties of lung SP cells
Authors: Reynolds Susan D. , Shen Hongmei , Reynolds Paul R. , Betsuyaku Tomoko , Pilewski Joseph M. , Gambelli Federica , DeGuiseppe Michelangelo , Ortiz Luis A. , Stripp Barry R.
Published: December 2006

Previous analysis of lung injury and repair has provided evidence for region-specific stem cells that maintain proximal and distal epithelial compartments. However, redundant expression of lineage markers by cells at several levels of the stem cell hierarchy has complicated phenotypic and functional characterization of clonogenic airway cells. Based on the demonstration that rapid efflux of the DNA dye Hoechst 33342 can be used to prospectively purify long-term repopulating hematopoietic stem cells, we hypothesized that lung cells with similar biochemical properties would be enriched for clonogenic progenitors. We demonstrate that Hoechst-dim side population (SP) cells isolated from proximal and distal compartments of the mouse lung were relatively small and agranular, exhibited low red and green autofluorescence, and that the SP fraction was highly enriched in clonogenic cells. Quantitative RT-PCR indicated that vimentin mRNA was enriched and that epithelial markers were depleted in these preparations of SP cells. Bleomycin exposure was associated with decreased clonogenicity among alveolar SP and suggested that SP cell function was compromised under profibrotic conditions. We conclude that the SP phenotype is common to clonogenic cells at multiple airway locations and suggest that Hoechst efflux is a property of cells expressing a wound-repair phenotype.
Inflammatory mediators modulate thrombin and cathepsin-G signaling in human bronchial fibroblasts by inducing expression of proteinase-activated receptor-4
Authors: Ramachandran Rithwik , Sadofsky Laura R. , Xiao Yupei , Botham Andrew , Cowen Michael , Morice Alyn H. , Compton Steven J
Published: December 2006

Human lung fibroblasts express proteinase-activated receptor-1 (PAR1), PAR2 and PAR3, but not PAR4. Because PAR2 has inflammatory effects on human primary bronchial fibroblasts (HPBF), we asked 1) whether the inflammatory mediators TNF-α and LPS could modify HPBF PAR expression and 2) whether modified PAR expression altered HPBF responsiveness to PAR agonists in terms of calcium signaling and cell growth. TNF-α and LPS induced PAR4 mRNA expression (RT-PCR) at 6 h and 24 h, respectively. TNF-α and LPS also upregulated PAR2 mRNA expression with similar kinetics but had negligible effect on PAR1 and PAR3. Flow cytometry for PAR1, PAR2, and PAR3 also demonstrated selective PAR2 upregulation in response to TNF-α and LPS. Intracellular calcium signaling to SLIGKV-NH2 (a selective PAR2-activating peptide; PAR2-AP) and AYPGQV-NH2 (PAR4-AP) revealed that TNF-α and LPS induced maximal responses to these PAR agonists at 24 h and 48 h, respectively. Upregulation of PAR2 by TNF-α heightened HPBF responses to trypsin, while PAR4 induction enabled cathepsin-G-mediated calcium signaling. Cathepsin-G also disarmed PAR1 and PAR2 in HPBF, while tryptase disarmed PAR2. Induction of PAR4 also enabled thrombin to elicit a calcium signal through both PAR1 and PAR4, as determined by a desensitization assay. In cell growth assays the PAR4 agonists cathepsin-G and AYPGQV-NH2 reduced HPBF cell number only in TNF-α-treated HPBF. Moreover, the mitogenic effect of thrombin (a PAR1/PAR4 agonist) but not the PAR1-AP TFLLR-NH2, was ablated in TNF-α-treated HPBF. These findings point to an important mechanism, whereby cellular responses to thrombin and cathepsin-G can be modified during an inflammatory response.
Postpartum Morbidity Associated With Advanced HIV Disease
Authors: Louis Judette , Buhari Mudathiru A. , Allen Dianne , Gonik Bernard , Jones Theodore B.
Published: December 2006

Objective. To investigate the postpartum morbidity and postpartum
management of febrile morbidity associated with advanced HIV
infection. Methods. A case control study of HIV infected women at a tertiary
care center during January 2000–June 2005 was performed.
Postpartum morbidity was defined as endometritis, blood
transfusion, wound complication, readmission, infectious morbidity,
or unexpected surgery. Results. Women in Group 1 had AIDS (N = 33), Group 2 were relatively immunocompetent HIV infected women (N = 115), and Group 3 were uninfected women (N = 152). Group 1 was more likely to have a postpartum morbidity (32.3 versus 19.3 and 13.2%, P = .03) and to have postpartum imaging 18.8 versus 7.9 and 2.6%, P = .002. After controlling for potential confounders, cesarean delivery (OR 6.2, 95% CI 2.1–505.5) but not advanced HIV disease was associated with an increased risk of postpartum morbidity. Conclusion. Cesarean delivery and not advanced HIV disease
increases the risk of postpartum morbidity in women with AIDS.
Numerical and Experimental Investigations of Steady Micro‐Tip Injection on a Subsonic Axial‐Flow Compressor Rotor
Authors: Lu Xingen , Chu Wuli , Zhu Junqiang , Tong Zhiting
Published: December 2006

Steady tip injection has been demonstrated to be an effective means of extending the stable operating range of a tip‐critical compressor. This study presents a state‐of‐the‐art design for the tip injection through the casing with flush‐mounted inclined holes and the effectiveness of steady micro‐air injection to enhance stability in a subsonic axial‐flow compressor rotor using an external‐air supply. For the tested rotor, experimental results demonstrate that at 53% design speed, the stalling mass flow can be reduced by 7.69% using an injected mass flow equivalent to 0.064% of the annulus flow. Time‐dependent CFD simulations were conducted to identify the physical mechanic that accounts for the beneficial effects of the steady micro‐air injection on the performance and stability of the compressor. Detailed analyses of the flow visualization at the tip have exposed the different tip flow topologies between the cases without tip injection and with tip injection. It was found that the primary stall margin enhancement afforded by the steady micro‐air injection is a result of the
tip‐clearance flow manipulation. The repositioning of the tip‐clearance vortex further towards the trailing edge of the blade passage and delaying the movement of incoming/tip‐clearance flow interface to the leading edge plane are the physical mechanisms responsible for extending the compressor stall margin.
Modeling granular materials as compressible nonlinear fluids: Heat transfer boundary value problems
Authors: Massoudi Mehrdad , Phuoc Tran X.
Published: December 2006

We discuss three boundary value problems in the flow and heat transfer analysis in flowing granular materials: (i) the flow down an inclined plane with radiation effects at the free surface; (ii) the natural convection flow between two heated vertical walls; (iii) the shearing motion between two horizontal flat plates with heat conduction. It is assumed that the material behaves like a continuum, similar to a compressible nonlinear fluid where the effects of density gradients are incorporated in the stress tensor. For a fully developed flow the equations are simplified to a system of three nonlinear ordinary differential equations. The equations are made dimensionless and a parametric study is performed where the effects of various dimensionless numbers representing the effects of heat conduction, viscous dissipation, radiation, and so forth are presented.
Histone Deacetylase (HDAC) Inhibitor LBH589 Increases Duration of γ-H2AX Foci and Confines HDAC4 to the Cytoplasm in Irradiated Non–Small Cell Lung Cancer
Authors: Geng Ling , Cuneo Kyle C. , Fu Allie , Tu Tianxiang , Atadja Peter W. , Hallahan Dennis E.
Published: December 2006

Histone deacetylases (HDAC) have been identified as therapeutic targets due to their regulatory function in DNA structure and organization. LBH589 is a novel inhibitor of class I and II HDACs. We studied the effect of LBH589 and ionizing radiation (IR) on DNA repair in two human non–small cell lung cancer (NSCLC) cell lines (H23 and H460). γ-H2AX foci present at DNA double-strand breaks (DSBs) were detected in the nuclei following 3 Gy irradiation for up to 6 hours. LBH589 administered before irradiation increased the duration of γ-H2AX foci beyond 24 hours. Furthermore, radiation alone induced translocation of HDAC4 to the nucleus. In contrast, treatment with LBH589 followed by irradiation resulted in HDAC4 confinement to the cytoplasm, indicating that HDAC inhibition affects the nuclear localization of HDAC4. The findings that LBH589 confines HDAC4 to the cytoplasm and increases the duration of γ-H2AX foci in irradiated cell lines suggest that HDAC4 participates in DNA damage signaling following IR. Annexin-propidium iodide flow cytometry assays, cell morphology studies, and cleaved caspase-3 Western blot analysis revealed a synergistic effect of LBH589 with IR in inducing apoptosis. Clonogenic survival showed a greater than additive effect when LBH589 was administered before irradiation compared with irradiation alone. In vivo tumor volume studies showed a growth delay of 20 days with combined treatment compared with 4 and 2 days for radiation or LBH589 alone. This study identifies HDAC4 as a biomarker of LBH589 activity and recognizes the ability of LBH589 to sensitize human NSCLC to radiation-induced DNA DSBs. (Cancer Res 2006; 66(23): 11298-304)
Androgen Receptor Coactivators Lysine-Specific Histone Demethylase 1 and Four and a Half LIM Domain Protein 2 Predict Risk of Prostate Cancer Recurrence
Authors: Kahl Philip , Gullotti Lucia , Heukamp Lukas Carl , Wolf Susanne , Friedrichs Nicolaus , Vorreuther Roland , Solleder Gerold , Bastian Patrick J. , Ellinger Jörg , Metzger Eric , Schüle Roland , Buettner Reinhard
Published: December 2006

Prostate cancer biology varies from locally confined tumors with low risk for relapse to tumors with high risk for progression even after radical prostatectomy. Currently, there are no reliable biomarkers to predict tumor relapse and poor clinical outcome. In this study, we correlated expression patterns of the androgen receptor (AR) coactivators lysine-specific histone demethylase 1 (LSD1) and four and a half LIM-domain protein 2 (FHL2), AR, Gleason score, Gleason grade, and p53 expression in clinically organ confined prostate cancers with relapse after radical prostatectomy. Our data reveal that high levels of LSD1, nuclear expression of the FHL2 coactivator, high Gleason score and grade, and very strong staining of nuclear p53 correlate significantly with relapse during follow-up. No correlation exists with relapse and the expression of AR and cytoplasmic expression of FHL2. To confirm these data, we did quantitative reverse transcription-PCR and Western blot analyses in a subset of tumor specimens. Consistently, both LSD1 mRNA and protein levels were significantly up-regulated in high-risk tumors. We previously identified LSD1 and FHL2 as nuclear cofactors interacting specifically with the AR in prostate cells and showed that both stimulate androgen-dependent gene transcription. Our present study suggests that LSD1 and nuclear FHL2 may serve as novel biomarkers predictive for prostate cancer with aggressive biology and point to a role of LSD1 and FHL2 in constitutive activation of AR-mediated growth signals. (Cancer Res 2006; 66(23): 11341-7)
A Novel BH3 Mimetic Reveals a Mitogen-Activated Protein Kinase–Dependent Mechanism of Melanoma Cell Death Controlled by p53 and Reactive Oxygen Species
Authors: Verhaegen Monique , Bauer Joshua A. , Martín de la Vega Cristina , Wang Guoping , Wolter Keith G. , Brenner J. Chadwick , Nikolovska-Coleska Zaneta , Bengtson Audrey , Nair Rajan , Elder James T. , Van Brocklin Matt , Carey Thomas E. , Bradford Carol R. , Wang Shaomeng , Soengas María S.
Published: December 2006

The RAS/BRAF/MEK/ERK mitogen-activated protein kinase (MAPK) pathway is emerging as a key modulator of melanoma initiation and progression. However, a variety of clinical studies indicate that inhibiting the MAPK pathway is insufficient per se to effectively kill melanoma cells. Here, we report on a genetic and pharmacologic approach to identify survival factors responsible for the resistance of melanoma cells to MEK/ERK antagonists. In addition, we describe a new tumor cell–selective means to bypass this resistance in vitro and in vivo. By generating a panel of isogenic cell lines with specific defects in the apoptotic machinery, we found that the ability of melanoma cells to survive in the absence of functional MEK relies on an ERK-independent expression of the antiapoptotic factor Mcl-1 (and to a lesser extent, Bcl-xL and Bcl-2). Using computer-based modeling, we developed a novel Bcl-2 homology domain 3 (BH3) mimetic. This compound, named TW-37, is the first rationally designed small molecule with high affinity for Mcl-1, Bcl-xL, and Bcl-2. Mechanistic analyses of the mode of action of TW-37 showed a synergistic tumor cell killing in the presence of MEK inhibitors. Importantly, TW-37 unveiled an unexpected role of the MAPK pathway in the control of reactive oxygen species (ROS). This function was critical to prevent the activation of proapoptotic functions of p53 in melanoma cells, but surprisingly, it was dispensable for normal melanocytes. Our results suggest that this MAPK-dependent ROS/p53 feedback loop is a point of vulnerability of melanoma cells that can be exploited for rational drug design. (Cancer Res 2006; 66(23): 11348-59)
Cyclin D1 Is Necessary for Tamoxifen-Induced Cell Cycle Progression in Human Breast Cancer Cells
Authors: Kilker Robin L. , Planas-Silva Maricarmen D.
Published: December 2006

Despite the success of tamoxifen in treating hormone-responsive breast cancer, its use is limited by the development of resistance to the drug. Understanding the pathways involved in the growth of tamoxifen-resistant cells may lead to new ways to treat tamoxifen-resistant breast cancer. Here, we investigate the role of cyclin D1, a mediator of estrogen-dependent proliferation, in growth of tamoxifen-resistant cells using a cell culture model of acquired resistance to tamoxifen. We show that tamoxifen and 4-hydroxytamoxifen (OHT) promoted cell cycle progression of tamoxifen-resistant cells after growth-arrest mediated by the estrogen receptor down-regulator ICI 182,780. Down-regulation of cyclin D1 with small interfering RNA blocked basal cell growth of tamoxifen-resistant cells and induction of cell proliferation by OHT. In addition, pharmacologic inhibition of phosphatidylinositol 3-kinase/Akt or mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 pathways decreased basal cyclin D1 expression and impaired OHT-mediated cyclin D1 induction and cell cycle progression. These findings indicate that cyclin D1 expression is necessary for proliferation of tamoxifen-resistant cells and for tamoxifen-induced cell cycle progression. These results suggest that therapeutic strategies to block cyclin D1 expression or function may inhibit development and growth of tamoxifen-resistant tumors. (Cancer Res 2006; 66(23): 11478-84)
p50 Nuclear Factor-κB Overexpression in Tumor-Associated Macrophages Inhibits M1 Inflammatory Responses and Antitumor Resistance
Authors: Saccani Alessandra , Schioppa Tiziana , Porta Chiara , Biswas Subhra K. , Nebuloni Manuela , Vago Luca , Bottazzi Barbara , Colombo Mario P. , Mantovani Alberto , Sica Antonio
Published: December 2006

Tumor-associated macrophages (TAM) are a major inflammatory infiltrate in tumors and a major component of the protumor function of inflammation. TAM in established tumors generally have an M2 phenotype with defective production of interleukin-12 (IL-12) and high IL-10. Here, we report that defective responsiveness of TAM from a murine fibrosarcoma and human ovarian carcinoma to M1 activation signals was associated with a massive nuclear localization of the p50 nuclear factor-κB (NF-κB) inhibitory homodimer. p50 overexpression inhibited IL-12 expression in normal macrophages. TAM isolated from p50−/− mice showed normal production of M1 cytokines, associated with reduced growth of transplanted tumors. Bone marrow chimeras showed that p50 inactivation in hematopoietic cells was sufficient to result in reduced tumor growth. Thus, p50 NF-κB overexpression accounts for the inability of TAM to mount an effective M1 antitumor response capable of inhibiting tumor growth. (Cancer Res 2006; 66(23): 11432-40)
Loss of Nrdp1 Enhances ErbB2/ErbB3–Dependent Breast Tumor Cell Growth
Authors: Yen Lily , Cao Zhongwei , Wu Xiuli , Ingalla Ellen R.Q. , Baron Colin , Young Lawrence J.T. , Gregg Jeffrey P. , Cardiff Robert D. , Borowsky Alexander D. , Sweeney Colleen , Carraway Kermit L.
Published: December 2006

Dysregulation of ErbB receptor tyrosine kinases is thought to promote mammary tumor progression by stimulating tumor cell growth and invasion. Overexpression and aberrant activation of ErbB2/HER2 confer aggressive and malignant characteristics to breast cancer cells, and patients displaying ErbB2-amplified breast cancer face a worsened prognosis. Recent studies have established that ErbB2 and ErbB3 are commonly co-overexpressed in breast tumor cell lines and in patient samples. ErbB2 heterodimerizes with and activates the ErbB3 receptor, and the two receptors synergize in promoting growth factor–induced cell proliferation, transformation, and invasiveness. Our previous studies have shown that the neuregulin receptor degradation protein-1 (Nrdp1) E3 ubiquitin ligase specifically suppresses cellular ErbB3 levels by marking the receptor for proteolytic degradation. Here, we show that overexpression of Nrdp1 in human breast cancer cells results in the suppression of ErbB3 levels, accompanied by the inhibition of cell growth and motility and the attenuation of signal transduction pathways. In contrast, either Nrdp1 knockdown or the overexpression of a dominant-negative form enhances ErbB3 levels and cellular proliferation. Additionally, Nrdp1 expression levels inversely correlate with ErbB3 levels in primary human breast cancer tissue and in a mouse model of ErbB2 mammary tumorigenesis. Our observations suggest that Nrdp1-mediated ErbB3 degradation suppresses cellular growth and motility, and that Nrdp1 loss in breast tumors may promote tumor progression by augmenting ErbB2/ErbB3 signaling. (Cancer Res 2006; 66(23): 11279-86)
Genome-Wide Allelic Imbalance Analysis of Pediatric Gliomas by Single Nucleotide Polymorphic Allele Array
Authors: Wong Kwong-Kwok , Tsang Yvonne T.M. , Chang Yi-Mieng , Su Jack , Di Francesco Angela M. , Meco Daniela , Riccardi Riccardo , Perlaky Laszlo , Dauser Robert C. , Adesina Adekunle , Bhattacharjee Meenakshi , Chintagumpala Murali , Lau Ching C.
Published: December 2006

Using single nucleotide polymorphic (SNP) allele arrays, we analyzed 28 pediatric gliomas consisting of 14 high-grade gliomas and 14 low-grade gliomas. Most of the low-grade gliomas had no detectable loss of heterozygosity (LOH) in any of the 11,562 SNP loci; exceptions were two gangliogliomas (3q and 9p), one astrocytoma (6q), and two subependymal giant cell astrocytomas (16p and 21q). On the other hand, all high-grade gliomas had various degrees of LOH affecting 52 to 2,168 SNP loci on various chromosomes. LOH occurred most frequently in regions located at 4q (54%), 6q (46%), 9p (38%), 10q (38%), 11p (38%), 12 (38%), 13q (69%), 14q (54%), 17 (38%), 18p (46%), and 19q (38%). We also detected amplifications of epidermal growth factor receptor (EGFR) or platelet-derived growth factor receptor α (PDGFRα) in a few of the 13 cases of glioblastoma multiforme analyzed. Interestingly, the amplified EGFR and PDGFRα were located within regions of LOH. SNP loci with LOH and copy number changes were validated by sequencing and quantitative PCR, respectively. Our results indicate that, in some pediatric glioblastoma multiforme, one allele each of EGFR and PDGFRα was lost but the remaining allele was amplified. This may represent a new molecular mechanism underlying tumor progression. (Cancer Res 2006; 66(23): 11172-8)
Inhibition of Growth and Metastasis of Human Hepatocellular Carcinoma by Antisense Oligonucleotide Targeting Signal Transducer and Activator of Transcription 3
Authors: Li Wen-Chang , Ye Sheng-Long , Sun Rui-Xia , Liu Yin-Kun , Tang Zhao-You , Kim Youngsoo , Karras James G. , Zhang Hong
Published: December 2006

Purpose: Hepatocellular carcinoma (HCC) is an aggressive malignancy and is a devastating clinical complication of chronic liver disease. Therapeutic options are limited mainly because the genetic and biochemical understanding of this disease remains fragmented. We intended to study the role of signal transducer and activator of transcription 3 (STAT3) aberrant signaling in HCC malignancy, and the therapeutic potential of inhibition of STAT3 expression for HCC.

Experimental Design: A 2′-O-methoxyethylribose–modified phosphorothioate antisense oligonucleotide (ASO) was used to knock down STAT3 expression in different human HCC cell lines, including the highly metastatic HCCLM3 derived from orthotopic implantation and subsequent lung metastasis in athymic mice. The effects of STAT3 ASO treatment on HCC cells, metastasis, and animal survival following HCCLM3 orthotopic implantation were evaluated.

Results: Specific suppression of phosphorylated STAT3 reduced its DNA-binding activity, inhibited the expression of vascular endothelial growth factor, survivin, matrix metalloproteinases 2 and 9, reduced cell proliferation and migratory potential, induced apoptosis in vitro, and inhibited intradermal angiogenesis and s.c. tumorigenesis upon injection in mice. In mice bearing orthotopically implanted HCCLM3, STAT3 inhibition following therapeutic treatment with STAT3 ASO reduced circulating vascular endothelial growth factor and basic fibroblast growth factor, decreased intratumor CD34-positive microvessel density, intrahepatic and intraperitoneal transmission, and lung metastasis. HCC tumor volume and weight were reduced and the survival time of mice bearing orthotopically xenografted HCC was approximately doubled in STAT3 ASO–treated mice (P < 0.05).

Conclusions: Constitutively activated STAT3 is essential for the growth, survival, and metastasis of HCC, suggesting that STAT3-targeted therapy may have utility for HCC.
In vivo Radioprotection by the Fullerene Nanoparticle DF-1 as Assessed in a Zebrafish Model
Authors: Daroczi Borbala , Kari Gabor , McAleer Mary Frances , Wolf Jeffrey C. , Rodeck Ulrich , Dicker Adam P.
Published: December 2006

Purpose: We have previously shown that zebrafish (Danio rerio) embryos can be used as an in vivo model to validate modifiers of the radiation response. Here, we evaluated the radioprotective effect of the nanoparticle DF-1, a fullerene with antioxidant properties, in zebrafish embryos.

Experimental Design: Zebrafish embryos were exposed to different doses of ionizing radiation ranging from 20 to 80 Gy in the presence and absence of DF-1. Toxicity and radioprotective effects were assessed by monitoring overall survival and morphology as well as organ functions by employing assays to measure kidney excretory function and development of sensory nerve cells (neuromasts). Antioxidant properties of DF-1 were assessed in whole fish.

Results: DF-1 had no apparent adverse effects on normal zebrafish morphology or viability throughout the concentration range tested (1-1,000 μmol/L). Ionizing radiation (10-40 Gy) caused time-dependent and dose-dependent perturbations of normal zebrafish morphology and physiology, notably defective midline development resulting in dorsal curvature of the body axis (“curly-up”), neurotoxicity, impaired excretory function, and decreased survival of the exposed embryos. DF-1 (100 μmol/L) markedly attenuated overall and organ-specific radiation-induced toxicity when given within 3 hours before or up to 15 minutes after radiation exposure. By contrast, DF-1 afforded no protection when given 30 minutes after ionizing radiation. The degree of radioprotection provided by DF-1 was comparable with that provided by the Food and Drug Administration–approved radioprotector amifostine (4 mmol/L). Protection against radiation-associated toxicity using DF-1 in zebrafish embryos was associated with marked reduction of radiation-induced reactive oxygen species.

Conclusion: The fullerene DF-1 protects zebrafish embryos against deleterious effects of ionizing radiation due, in part, to its antioxidant properties.