bluuebunny/crossref_metadata_2025 huggingface dataset:
E-Cadherin Inhibits the Growth of Single Cells
Authors: Foley John F.
Published: July 2007

E-cadherin is found at the junctions of epithelial cells. Besides mediating cell-cell adhesion through homophilic interactions (E-cadherin from one cell binding to E-cadherin on an adjacent cell), E-cadherin mediates contact inhibition of cell growth, and loss of E-cadherin is associated with tumorigenesis. As a result of the many molecular interactions that occur between cells at junctions, it has been unclear whether E-cadherin alone can inhibit cell growth in the absence of cell contact. Perrais
et al
. devised an experimental system designed to monitor the effects of ligation of E-cadherin on the growth of single cells. The authors exposed single epithelial cells, attached to fibronectin-coated coverslips, to microspheres coated with chimeric proteins of the extracellular domain of E-cadherin fused to the immunoglobulin Fc domain (Fc-hE). Exposure of single cells to Fc-hE-microspheres resulted in decreased BrdU incorporation (a marker of DNA replication), as measured by immunofluorescence microscopy, compared with that in cells exposed to control microspheres, which indicates that ligation of E-cadherin on these cells resulted in decreased cellular proliferation. Cadherins mediate cell-cell adhesion in part through interactions of their cytoplasmic domains with catenins. Through the use of mutated forms of E-cadherin in epithelial cell lines, the authors found that the β-catenin binding domain of E-cadherin was necessary for the inhibition of cellular proliferation. Knockdown of β-catenin by siRNA eliminated E-cadherin-mediated inhibition of cell growth, resulting in increased cellular proliferation. E-cadherin-mediated inhibition of cell growth, however, was not dependent on β-catenin-dependent transcriptional activation. Ligation of E-cadherin by Fc-hE-microspheres inhibited cell growth stimulated by epidermal growth factor (EGF) in epithelial cell lines. This effect of E-cadherin was also dependent on the presence of β-catenin. Whereas E-cadherin ligation did not inhibit either the autophosphorylation of the EGF receptor (EGFR) or EGFR-mediated activation of extracellular signal-regulated kinase (ERK), it did inhibit the transphosphorylation of the Tyr845 residue of EGFR and the subsequent activation of signal transducer and activator of transcription 5 (STAT5). Together these data suggest that homophilic ligation of E-cadherin can inhibit cell growth and EGFR signaling independently of cell-cell contact.

M. Perrais, X. Chen, M. Perez-Moreno, B. M. Gumbiner, E-cadherin homophilic ligation inhibits cell growth and epidermal growth factor receptor signaling independently of other cell interactions.
Mol. Biol. Cell
18
, 2013-2025 (2007).
[Abstract]
[Full Text]
Tumor Necrosis Factor Member Promotes Sustained Toll-Like Receptor Signaling
Authors: Ray L. Bryan
Published: July 2007

Macrophages of the innate immune system have Toll-like receptors (TLRs) that recognize bacterial components such as lipopolysaccharide (LPS) and initiate signaling cascades that lead to the production of inflammatory cytokines. Although these responses are initiated within hours, they can continue for at least 24 hours. The sustained response may be of particular relevance to diseases characterized by excessive inflammation. Kang
et al
. implicate a type-2 transmembrane protein, 4-1BBL (also called CD137L)--a member of the tumor necrosis factor (TNF) superfamily--in such sustained cytokine production by macrophages. The authors detected 4-1BBL in a two-hybrid screen for proteins that interacted with the intracellular domain of TLR4 and further supported possible interaction of the proteins in human embryonic kidney 293T cells overexpressing tagged versions of the proteins. Mouse macrophages stimulated with LPS to activate TLRs rapidly expressed 4-1BBL at the cell surface, and macrophages lacking 4-1BBL that were treated with LPS produced smaller amounts of TNF, interleukin-6 (IL-6), and IL-12 24 hours after stimulation than did similarly treated wild-type cells. More rapid cytokine production (within the first few hours) in response to LPS was similar in both cell types. The 4-1BBL acts as a ligand for the receptor 4-1BB in T cells, but 4-1BB appeared not to be required for the promotion of cytokine production by 4-1BBL because macrophages lacking 4-1BB produced normal amounts of TNF after stimulation with LPS. The authors suggest that 4-1BBL may produce a signal itself on the basis of experiments in which 4-1BBL was cross-linked on the surface of macrophages, perhaps as part of a complex with TLRs. In wild-type macrophages, the authors found evidence for two sequential signaling complexes containing TLR4. Early on, immunoprecipitation showed association of TLR4 with the signaling adaptor MyD88. Later, they saw association of TLR4 and 4-1BBL, but no association of 4-1BBL and MyD88 was detected. The more persistent complex with 4-1BBL, the authors note, may be a useful target for strategies aimed at treatment of inflammatory diseases

Y. J. Kang, S. O. Kim, S. Shimada, M. Otsuka, A. Seit-Nebi, B. S. Kwon, T. H. Watts, J. Han, Cell surface 4-1BBL mediates sequential signaling pathways ‘downstream’ of TLR and is required for sustained TNF production in macrophages.
Nat. Immunol.
8
, 601-609 (2007).
[PubMed]
Virulent Protein Kinase A
Authors: Gough Nancy R.
Published: July 2007

The
Yersinia
Gram-negative bacteria are pathogenic to humans causing such diseases as bubonic plague. Through the action of a type III protein secretion system, Yersinia injects bacterial proteins necessary to subvert the host cell's normal processes and to promote bacterial survival and replication. Navarro
et al
. report that, in addition to the previously known inhibitory activity toward guanosine triphosphatases (GTPases) Rac1 and RhoA,
Yersinia
protein kinase A (YpkA) also inhibits G protein (heterotrimeric guanine nucleotide-binding protein) signaling by phosphorylation of the Gα subunit. The actin cytoskeleton disruption in cells expressing either the full-length YpkA or a C-terminal fragment was prevented if the cells also expressed a constitutively active form of RhoA, suggesting that YpkA acted upstream of this GTPase. G protein-coupled receptors can stimulate reorganization of the actin cytoskeleton through the activation of RhoA. Exposure of cells transfected with the muscarinic receptor to carbachol stimulated Gα
q
signaling and promoted the formation of stress fibers. Transfection of YpkA, but not a catalytically inactive version, inhibited this Gα
q
-induced reorganization of the cytoskeleton. YpkA coimmunoprecipitated with Gα
q
(both GDP-bound and GTP-bound forms) and Gα
q
was phosphorylated when immunoprecipitated from cells expressing catalytically active YpkA. The phosphorylation site was mapped to a serine within the consensus guanine nucleotide-binding loop by liquid chromatography tandem mass spectrometry. Phosphorylation of this residue appeared to disrupt activation of the G protein as substitution of the serine with aspartate (to mimic phosphorylation) prevented GTP loading. Not only was signaling from the muscarinic receptor to the cytoskeleton blocked by expression of YpkA, so was nuclear translocation of tubby, a transcriptional regulator released from the plasma membrane in response to Gα
q
-mediated stimulation of phospholipase C. In cells infected with
Yersinia
, both wild-type and catalytically inactive YpkA disrupted the actin cytoskeleton, presumably because the protein contains two functional domains that can inhibit the actin cytoskeleton: the C-terminal guanine nucleotide dissociation inhibitor region that directly targets RhoA and the serine-threonine kinase activity of the N-terminal region that inhibits G protein signaling to the cytoskeleton.

L. Navarro, A. Koller, R. Nordfelth, H. Wolf-Watz, S. Taylor, J. E. Dixon, Identification of a molecular target for the
Yersinia
protein kinase A.
Mol. Cell
26
, 465-477 (2007).
[PubMed]
Transcriptional Response to Nod Signaling
Authors: Gough Nancy R.
Published: July 2007

Nitrogen fixation occurs in the root nodules of legumes that form as part of a symbiotic process with rhizobial bacteria. Although the transcriptional regulators of the GRAS family were identified as important for mediating the plant response to the bacterial Nod factor that induces nodule formation, these GRAS proteins may not directly bind DNA. Middleton
et al
. identify ERN, a member of the ERF subfamily of transcription factors with the AP2 domain that bind DNA, as a participant in Nod signaling in
Medicago truncatula
. The authors screened plants deficient in nodule formation and identified two alleles called
bit1-1
and
bit1-2
. Plants carrying either of these alleles not only failed to form nodules in response to rhizobial infection but also failed to form nodules in response to a constitutively active form of calcium- and calmodulin-dependent protein kinase (CCaMK) that causes spontaneous nodule formation. The
bit1-1
plants were also defective in activation of a Nod factor reporter gene. Genetic mapping of these alleles revealed that they encoded point mutations in the DNA binding domain (
bit1-2
) or deletions (
bit1-1
) in a gene that encodes a protein with sequence similarity to ERF transcription factors. They named this protein ERN for ERF Required for Nodulation. Rhizobial inoculation stimulated the expression of
ERN
, and this required a functional Nod signaling response. Consistent with a role in transcriptional response to Nod signaling, microarray analysis of plants with the
bit1-1
allele showed decreased transcriptional responsiveness to rhizobial infection. Whether ERN interacts with GRAS transcriptional regulators and whether ERN binds to the promoters of Nod-regulated genes remains to be determined.

P. H. Middleton, J. Jakab, R. V. Penmetsa, C. G. Starker, J. Doll, P. Kaló, R. Prabhu, J. F. Marsh, R. M. Mitra, A. Kereszt, B. Dudas, K. VandenBosch, S. R. Long, D. R. Cook, G. B. Kiss, G. E. D. Oldroyd, An ERF transcription factor in
Medicago truncatula
that is essential for Nod factor signal transduction.
Plant Cell
19
, 1221-1234 (2007).
[Abstract]
[Full Text]
Designer Proteasome
Authors: Simpson Stephen J.
Published: July 2007

In the immune system, T cells respond to fragments of antigenic proteins presented at the cell surface by molecules encoded by genes of the major histocompatibility complex. This process is vital not only for recognition of antigens carried by pathogens and tumors but also in the selection of T cells as they develop in the thymus. A large multisubunit complex called the proteasome, which exists in a variety of forms containing different catalytic subunits, generates these peptides. Murata
et al.
(see the Perspective by Bevan) now identify a proteasome subunit, β5t, that was found exclusively in the thymic epithelial cells and directs positive selection of T cells. Indeed, mice lacking β5t showed significant disruption of T cell development.

S. Murata, K. Sasaki, T. Kishimoto, S.-i. Niwa, H. Hayashi, Y. Takahama, K. Tanaka, Regulation of CD8
+
T cell development by thymus-specific proteasomes.
Science
316
, 1349-1353 (2007).
[Abstract]
[Full Text]

M. J. Bevan, The cutting edge of T cell selection.
Science
316
, 1291-1292 (2007).
[Summary]
[Full Text]
In SYNC: The Ins and Outs of Circadian Oscillations in Calcium
Authors: Imaizumi Takato , Schroeder Julian I. , Kay Steve A.
Published: July 2007

Many stimuli induce short-term increases in the cytosolic concentration of free calcium ions ([Ca
2+
]
i
) that encode signaling information about diverse physiological and developmental events. Slow cytosolic Ca
2+
oscillations that span an entire day have also been discovered in both plants and animals; it is thought that these daily Ca
2+
oscillations may encode circadian clock signaling information. A recent study focusing on the characterization of the extracellular Ca
2+
-sensing receptor (CAS) has provided insight into the molecular mechanisms by which the daily Ca
2+
oscillation in plants is generated. We summarize the major findings regarding daily oscillations of cytosolic Ca
2+
concentrations in plants and animals, and discuss hypothetical biological roles for the circadian clock–regulated physiology in plants.
Short Days and Estrogen Make for Short Tempers
Authors: Ray L. Bryan
Published: July 2007

The nuclear hormone estrogen is reported to increase aggressive behavior in most birds and domesticated mice but to reduce aggression in Bluebanded gobies, California mice, and humans. Trainor
et al
. present data showing that in their preferred model, male beach mice, estrogen can produce both effects, depending on the season (or, more precisely, the photoperiod to which the animal is exposed). Short, winterlike days cause testicular regression and aggressive behavior in these mice. In castrated mice (in which constant testosterone concentrations were provided by an implant) exposed to short days (8 hours of light and 16 hours of darkness), activation of estrogen receptors increased aggression (measured as the time elapsed before they attacked a male intruder in their home cage). But when the mice were maintained on long days (16 hours of light and 8 of darkness), estrogen treatment caused a decrease in aggression. Microarray analysis of gene expression in an area of the brain associated with aggression showed that the decrease in aggression produced in animals exposed to long days was associated with increased estrogen-dependent gene expression. The opposite effects of estrogen to increase aggression in animals exposed to short days could be detected within 15 minutes, a time frame likely to be too short for transcriptionally mediated effects. Thus, the authors propose that the increased aggression is influenced by nongenomic actions of estrogens. Together, the findings show that the effects of these nuclear receptors on aggressive behavior are highly dependent on environmental cues.

B. C. Trainor, S. Lin, M. S. Finy, M. R. Rowland, R. J. Nelson, Photoperiod reverses the effects of estrogens on male aggression via genomic and nongenomic pathways.
Proc. Natl. Acad. Sci. U.S.A.
104
, 9840-9845 (2007).
[Abstract]
[Full Text]
Target Identification Tool
Authors: Jasny Barbara
Published: July 2007

A challenge for functional genomics has been to make meaningful global measurements of the interactions between transcription factors (and cofactors) and DNA. It has been difficult, especially in large genomes, to explicitly map individual binding sites and individual factor-target gene interactions. Johnson
et al
. (see the Perspective by Fields) have developed a combination of chromatin immunoprecipitation and ultrahigh-throughput sequencing to achieve high specificity and 50-base pair resolution. This approach was used to study regulation by neuron-restrictive silencer factor (NRSF, also known as REST, for repressor element-1 silencing transcription factor) and identify targets of key positive regulators of pancreatic neuroendocrine development.

D. S. Johnson, A. Mortazavi, R. M. Myers, B. Wold, Genome-wide mapping of in vivo protein-DNA interactions.
Science
316
, 1497-1502 (2007).
[Abstract]
[Full Text]

S. Fields, Site-seeing by sequencing.
Science
316
, 1441-1442 (2007).
[Summary]
[Full Text]
Influenced by the Wrong Crowd
Authors: Adler Elizabeth M.
Published: July 2007

Two studies by Walkley
et al
. investigated the role of intrinsic and extrinsic factors in regulating cell cycle and fate of hematopoietic stem cells (HSCs), which reside in specialized niches in the bone marrow and give rise to the cells of the hematopoietic system (see Perry and Li). Although most HSCs maintain a relatively quiescent state, they can be stimulated to enter the cell cycle when hematopoiesis is required. The retinoblastoma (RB) tumor suppressor plays a critical role in cell cycle regulation and, in the first study, Walkley
et al
. examined the effects of
Rb
deletion on hematopoiesis. Widespread loss of RB throughout the mouse hematopoietic system led to profound myeloproliferation, characterized by an increase in the numbers of circulating progenitor cells and extramedullary hematopoiesis. There was a loss of trabecular bone (a HSC niche) and HSCs from the bone marrow, and eventual hematopoietic failure. When RB loss was restricted to cells of the myeloid lineage (granulocytes, macrophages, and osteoclasts), however, myeloproliferation did not occur. Transplantation indicated that loss of RB from hematopoietic niche alone was also not sufficient to elicit myeloproliferation. Rather, it depended on RB loss from both the bone marrow microenvironment and cells of myeloid lineage. In the second study, Walkley
et al
. showed that mice lacking the retinoic acid receptor γ (RARγ) also developed a myeloproliferative condition, with increased numbers of granulocytes in the bone marrow, peripheral blood, and spleen. Again, there was a loss of trabecular bone and excessive extramedullary hematopoiesis. In mice lacking RARγ, however, transplantation analysis indicated that myeloproliferation depended only on an abnormal bone marrow microenvironment. Loss of the RARγ was associated with an increase in tumor necrosis factor α (TNF-α) in bone marrow, thymus, and spleen; moreover, the hematological abnormalities were partially rescued in mice transplanted with hematopoietic cells lacking TNF-α. Both studies underline the importance of the bone marrow microenvironment to normal hematopoiesis and the contribution of an aberrant niche to myeloproliferative disease.

C. R. Walkley, J. M. Shea, N. A. Sims, L. E. Purton, S. H. Orkin, Rb regulates interactions between hematopoietic stem cells and their bone marrow microenvironment.
Cell
129
, 1081-1095 (2007).
[PubMed]

C. R. Walkley, G. Haines Olsen, S. Dworkin, S. A. Fabb, J. Swann, G. A. McArthur, S. V. Westmoreland, P. Chambon, D. T. Scadden, L. E. Purton, A microenvironment-induced myeloproliferative syndrome caused by retinoic acid receptor γ deficiency.
Cell
129
, 1097-1110 (2007).
[PubMed]

J. M. Perry, L. Li, Disrupting the stem cell niche: Good seeds in bad soil.
Cell
129
,1045-1047 (2007).
[PubMed]
Tuning Immune Stimulation
Authors: Simpson Stephen J. , Vinson Valda
Published: July 2007

During vaccination, an additional stimulus to the immune response is often needed and is provided by a material called an adjuvant. Lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria is a potent stimulant of the innate immune response, but the potential for toxic shock does not allow for its use in humans. A recently approved adjuvant, monophosphoryl lipid A (MPLA), has limited side effects compared with LPS, from which it is derived (see the Perspective by Fitzgerald and Golenbock). Mata-Haro
et al
. show that MPLA activates only a specific signaling component of the Toll-like receptor 4 (TLR4) pathway and avoids the myeloid differentiation factor 88 arm of TLR4 signaling, which can account for the much higher toxicity associated with LPS. Ohto
et al
. determined crystal structures of the TLR4 co-receptor MD-2 alone and in complex with the antiendotoxic tetra-acylated lipid A core of LPS. MD-2 has a deep hydrophobic cavity that accommodates the four acyl chains of the lipid core.

V. Mata-Haro, C. Cekic, M. Martin, P. M. Chilton, C. R. Casella, T. C. Mitchell, The vaccine adjuvant monophosphoryl lipid A as a TRIF-biased agonist of TLR4.
Science
316
, 1628-1632 (2007).
[Abstract]
[Full Text]

U. Ohto, K. Fukase, K. Miyake, Y. Satow, Crystal structures of human MD-2 and its complex with antiendotoxic lipid IVa.
Science
316
, 1632-1634 (2007).
[Abstract]
[Full Text]

K. A. Fitzgerald, D. T. Golenbock, The shape of things to come.
Science
316
, 1574-1576 (2007).
[Summary]
[Full Text]
Channeling a Metabolic Message
Authors: Adler Elizabeth M.
Published: July 2007

In many cells, loss of calcium from intracellular stores leads to calcium influx through store-operated calcium release-activated calcium (CRAC) channels; the development of microdomains of increased calcium concentration at the mouths of open CRAC channels elicits their rapid inactivation. Incoming calcium is accumulated in mitochondria, where it stimulates mitochondrial respiration and the production of ATP, thereby limiting calcium-dependent CRAC channel inactivation and sustaining calcium entry. Bakowski and Parekh recorded whole-cell CRAC currents of RBL-1 (rat basophilic leukemia) cells and found that pyruvic acid, a rate-limiting substrate for mitochondrial respiration, decreased rapid inactivation of CRAC channels. Pyruvate-derived metabolites had little or no effect on CRAC channel inactivation, nor did the effects of pyruvate depend on calcium uptake into mitochondria, or mitochondrial production of ATP. Experiments in which sodium replaced calcium as the ion carrying charge through the channel suggested that pyruvate interfered with the ability of calcium to mediate rapid inactivation of the CRAC channel. Thus, the authors propose that fluctuations in cytoplasmic pyruvate concentration--which would occur as a result of changes in mitochondrial respiration--provide a mechanism that directly links energy metabolism to the regulation of calcium influx.

D. Bakowski, A. B. Parekh, Regulation of store-operated calcium channels by the intermediary metabolite pyruvic acid.
Curr. Biol.
17
, 1076-1081 (2007).
[PubMed]
Frequency and fidelity of alien chromosome transmission inGossypiumhexaploid bridging populations
Authors: Becerra Lopez-Lavalle L. Augusto , Brubaker Curt L.
Published: July 2007

The Australian diploid Gossypium species possess traits of potential agronomical value, such as gossypol-free seeds and Fusarium wilt resistance. However, they belong to the tertiary germplasm pool, which is the most difficult group of species from which to introgress genes into G. barbadense L. and G. hirsutum L. Interspecific triploid hybrids can be generated but they are sterile. The sterility barrier can be overcome using synthetic polyploids as introgression bridges, but whether there is sufficient homoeologous chromosome interaction at meiosis to allow recombination is still an open question. To ascertain, genetically, observable levels of homoeologous introgression, 2 synthetic hexaploid lines (2x G. hirsutum × G. australe and 2x G. hirsutum × G. sturtianum) were crossed to G. hirsutum to generate pentaploid F1plants that, in turn, were backcrossed to G. hirsutum to generate BC1and BC2multiple alien chromosome addition lines (MACALs). Gossypium australe F. Muell. and G. sturtianum Willis chromosome-specific markers were used to track the frequency and fidelity of chromosome transmission to the BC1and BC2MACALs. The chromosomal location of the AFLP markers was determined by their distribution among the MACALs and confirmed in parental F2families. Roughly half the available chromosomes were transmitted to the G. hirsutum × G. australe (54%) and G. hirsutum × G. sturtianum (52%) BC1MACALs. The BC2MACAL families again inherited about half of the available chromosomes. There were, however, notable exceptions for specific chromosomes. Some chromosomes were preferentially eliminated, while others were preferentially transmitted. Consistent with the genomic stability of Gossypium synthetic polyploids, the de novo loss or gain of AFLP fragments was rarely observed. While restructuring of the donor G. australe and G. sturtianum chromosomes was observed, this is more likely the result of chromatin loss, and no clear cases of introgression of donor chromatin into the recipient G. hirsutum genome were observed.
Functional characterization of the transmembrane segment VII of the NHE1 isoform of the Na+/H+ exchangerThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Ding Jie , Ng Raymond W.P. , Fliegel Larry
Published: July 2007

The Na+/H+ exchanger isoform 1 is an integral membrane protein that regulates intracellular pH. It extrudes 1 intracellular H+ in exchange for 1 extracellular Na+. It has 2 large domains, an N-terminal membrane domain of 12 transmembrane segments and an intracellular C-terminal regulatory domain. We characterized the cysteine accessibility of amino acids of the critical transmembrane segment TM VII. Residues Leu 255, Leu 258, Glu 262, Leu 265, Asn 266, Asp 267, Val 269, Val 272, and Leu 273 were all mutated to cysteine residues in the cysteineless NHE1 isoform. Mutation of amino acids E262, N266, and D267 caused severe defects in activity and targeting of the intact full length protein. The balance of the active mutants were examined for sensitivity to the sulfhydryl reactive reagents, positively charged MTSET ((2- (trimethylammonium)ethyl)methanethiosulfonate) and negatively charged MTSES ((2-sulfonatoethyl)methanethiosulfonate). Leu 255 and Leu 258 were sensitive to MTSET but not to MTSES. The results suggest that these amino acids are pore-lining residues. We present a model of TM VII that shows that residues Leu 255, Leu 258, Glu 262, Asn 266, and Asp 267 lie near the same face of TM VII, lining the ion transduction pore.
Circulating stromal osteonectin-positive progenitor cells and stenotic coronary atherosclerosisThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Gabbasov Zufar A. , Agapov Alexander A. , Saburova Olga S. , Komlev Alexei E. , Soboleva Emma L. , Akchurin Renat S. , Smirnov Vladimir N.
Published: July 2007

The level of circulating stromal progenitor cells carrying osteonectin (ON), a marker of osteogenic differentiation, was evaluated by flow cytometry in blood of patients with coronary artery disease (CAD). Ninety-nine patients with CAD were included into the study. Coronary angiography of all patients showed critical stenosis of at least 2 coronary arteries or their major branches. The control groups included 8 patients without CAD and 19 healthy volunteers. In control patients, no lesions of the coronary bed were found by angiography. The absence of CAD in the volunteers was confirmed by bicycle stress test. The content of ON-positive cells in blood was examined in various populations of lymphocyte-like cells. It was found that the number of ON+ lymphocyte-like cells with CD41 positivity in blood of patients without coronary stenosis (0.27% ± 0.11%, mean ± SD) did not differ significantly from corresponding value in healthy volunteers (0.26% ± 0.07%, p = 0.94). In CAD patients, the percent of these ON+ cells was 1.01% ± 0.49% and was significantly higher than in blood of healthy volunteers (p < 0.0001) and patients without CAD (p < 0.0001). High content of ON+ lymphocyte-like cells with CD41 positivity in blood may serve as noninvasive marker of arterial atherosclerosis.
The single-strand DNA/RNA-binding protein, Purβ, regulates serum response factor (SRF)-mediated cardiac muscle gene expressionThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Gupta Madhu , Sueblinvong Vithida , Gupta Mahesh P.
Published: July 2007

Single-strand DNA-binding proteins, Purα and Purβ, play a role in cell growth and differentiation by modulating both transcriptional and translational controls of gene expression. We have previously characterized binding of Purα and Purβ proteins to a purine-rich negative regulatory (PNR) element of the rat cardiac α-myosin heavy chain (MHC) gene that controls cardiac muscle specificity. In this study we investigated the role of upstream sequences of the α-MHC promoter in Purβ-mediated gene repression. In the transient transfection analysis overexpression of Purβ revealed a negative regulatory effect on serum response factor (SRF)-dependent α-MHC and α-skeletal actin expression in muscle cell background. Contrary, in nonmuscle cells, Purβ showed no repressive effect. The results obtained from gel-shift assays demonstrated a sequence specific competitive binding of Purβ to the minus strand of the SRF-binding, CArG box sequences of different muscle genes, but not to the SRF-binding, SRE sequences of the c-fos gene. These element-specific associations of Purβ with muscle CArG boxes may, in part, explain why muscle gene expression is downregulated in disease states in which Purβ levels are elevated. This data also provide a mechanistic distinction between muscle CArG boxes and nonmuscle serum response element (SRE) sequences in terms of their affinity to bind to SRF and their ability to regulate cell-specific gene expression.
Thyroid hormone analog, diiodothyropropionic acid (DITPA), exerts beneficial effects on chamber and cellular remodeling in cardiomyopathic hamstersThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Kuzman James A. , Tang Yida , Vogelsang Kathryn A. , Said Suleman , Anderson Brent E. , Morkin Eugene , Gerdes A. Martin
Published: July 2007

Diiodothyropropionic acid (DITPA) is a thyroid hormone analog that is currently in phase II clinical trials. However, there have not been any studies to comprehensively analyze its effect on myocyte morphology. In addition, long-term studies with DITPA have not been done. This study compares the effects of DITPA with L-thyroxine (T4) on chamber remodeling, cardiac function, cellular morphology, cardiac blood flow, and protein expression. Normal and cardiomyopathic hamsters were treated with T4 or DITPA for 2 months. At the end of the treatment, echos, hemodynamics, coronary blood flow, cell morphology, and protein expression data were collected. Both T4 and DITPA treatment reduced chamber diameter during diastole, suggesting attenuated chamber dilatation in cardiomyopathic hamsters. Wall thickness also tended to increase, which was supported by cell morphology data in which DITPA significantly increased cross-sectional growth of myocytes specifically in the minor dimension, which is oriented transmurally. T4 and DITPA also increased myocardial blood flow both at baseline and after maximal dilation. This suggests there was increased angiogenesis or reduced loss of arterioles. Both T4 and DITPA had beneficial effects on chamber remodeling, which was most likely due to beneficial changes in cell shape and improved vascular supply.
Differential regulation of cholesterol homeostasis in transgenic mice expressing human cholesterol ester transfer proteinThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Agarwal-Mawal Alka , Murray Cathy M. , Belkhode Suresh , Cheema Sukhinder Kaur
Published: July 2007

We investigated whether expression of cholesterol ester transfer protein (CETP) in mice alters the regulation of cholesterol metabolism. Transgenic mice expressing human CETP (CETP-TG) and nontransgenic littermates (non-TG) were fed either a monounsaturated fatty acid (MUFA) or a saturated fatty acid (SFA)-rich diet in the presence or absence of cholesterol. Mice fed with MUFA diet had higher CETP activity compared with SFA-fed mice. Addition of cholesterol to the MUFA diet decreased CETP activity, whereas addition of cholesterol to the SFA diet had no effect. Cholesterol 7α-hydroxylase (Cyp7a) activity was higher in CETP-TG mice compared with non-TG mice when fed a MUFA diet, whereas SFA fed CETP-TG mice showed lower Cyp7a activity as compared with non-TG. Microsomal triglyceride transfer protein (MTTP) activity was higher in CETP-TG mice compared with non-TG mice when fed a MUFA diet. HMG-CoA reductase activity was lower in CETP-TG mice compared with non-TG mice when fed a MUFA or a SFA diet. These data demonstrate that the regulation of Cyp7a, HMG-CoA reductase, and MTTP is altered in CETP-TG mice as compared with non-TG mice and these alterations are further modulated by the quality of dietary fats. These findings highlight the importance of CETP in regulating cholesterol homeostasis.
SIMULATIONS OF FIELD-PLATED AND RECESSED GATE GALLIUM NITRIDE-BASED HETEROJUNCTION FIELD-EFFECT TRANSISTORS
Authors: Turin Valentin O. , Shur Michael S. , Veksler Dmitry B.
Published: July 2007

We report on two-dimensional isothermal simulations of recessed gate and field-plated AlGaN - GaN HFETs with submicron gates. The optimization of the recessed gate shape allows us to reduce the electric field at the drain-side gate edge by approximately 30%. Our simulations reveal a dramatic increase of the effective gate length with increasing drain-to-source bias with a commensurate decrease of the cutoff frequency (up to 40% decrease for 50V). To improve the cutoff frequency for the high drain-to-source bias, we suggest using the second field plate connected to the drain with a small gap between the two field plates. In this design, the electric field in the gap between the gate and the drain field plate is higher leading to a significant reduction of the effective gate length and, as a consequence, to an increase in the cutoff frequency at high drain-to-source biases (compared to the conventional design).
FIELD AND THERMIONIC FIELD TRANSPORT IN ALUMINIUM GALLIUM ARSENIDE HETEROJUNCTION BARRIERS
Authors: MORGAN D. V. , PORCH A.
Published: July 2007

A simplified model of electron transport by tunneling within a GaAs/AlGaAs/GaAs heterojunction is developed. The model is applied specifically to tunneling through a triangular barrier formed by the compositional grading of the AlGaAs region, but can in principle be extended to a range of barrier geometries encountered at heterojunction or metal/semiconductor interfaces. The experimental data for the current-voltage characteristics obtained for a range of temperatures from 77 K to 273 K are used to test the functional dependence obtained from calculations. Good agreement has been obtained between theory and experiment, thus confirming the usefulness of the simple model for device evaluation.
4H-SIC VERTICAL RESURF SCHOTTKY RECTIFIERS AND MOSFETS
Authors: Wang Y. , Losee P. A. , Chow T. P.
Published: July 2007

This work presents a vertical RESURF structure, which utilizes 2-dimensional depletion in semiconductor to achieve high blocking capability. This approach is then implemented into both 4 H - SiC Schottky rectifiers and MOSFETs. Device characteristics are analyzed with numerical simulations and compared with both conventional Schottky rectifiers and Superjunction structure. Design-of-Experiment (DOE) is also used to optimize the trade-off between several design parameters.
ABOVE 2 A/mm DRAIN CURRENT DENSITY OF GaN HEMTS GROWN ON SAPPHIRE
Authors: Medjdoub F. , Carlin J.-F. , Gonschorek M. , Feltin E. , Py M. A. , Grandjean N. , Kahn E.
Published: July 2007

We report on the investigation of an InAlN/GaN HEMT structure, delivering higher sheet carrier density than the commonly used AIGaN/GaN system. We achieved in a reproducible way more than 2 A/mm maximum drain current density for a gate length of 0.25 μm with unpassivated undoped devices realized on sapphire substrates. Small signal measurements yield a F T = 31 GHz and F MAX = 52 GHz , which illustrates the capability of these structures to operate at high frequencies. Moreover, the pulsed analysis indicates a more stable surface in the case of AlInN than that of AlGaN , attributed to the lattice matched growth of this barrier with 17% In content on GaN , avoiding strain piezo polarization in the material.
NEGATIVE BIAS TEMPERATURE INSTABILITY IN TIN/HF-SILICATE BASED GATE STACKS
Authors: CHOWDHURY N. A. , MISRA D. , RAHIM N.
Published: July 2007

This work studies the effects of negative bias temperature instability (NBTI) on p-channel MOSFETS with TiN/HfSi x O y (20% SiO 2 based high-κ gate stacks under different gate bias and elevated temperature conditions. For low bias conditions, threshold voltage shift (ΔVT) is most probably due to the mixed degradation within the bulk high-κ. For moderately high bias conditions, H-species dissociation in the presence of holes and subsequent diffusion may be initially responsible for interface state and positively charged bulk trap generation. Initial time, temperature and oxide electric field dependence of ΔVT in our devices shows an excellent match with that of SiO 2 based devices, which is explained by reaction-diffusion (R-D) model of NBTI. Under high bias condition at elevated temperatures, due to higher Si - H bond-annealing/bond-breaking ratio, the experimentally observed absence of the impact ionization induced hot holes at the interfacial layer (IL)/ Si interface probably limits the interface state generation and ΔVT as they quickly reach saturation.
POWER ADAPTIVE CONTROL OF DENSE CONFIGURED SUPER-SELF-ALIGNED BACK-GATE PLANAR TRANSISTORS
Authors: LIN HAO , LIU HAITAO , KUMAR ARVIND , AVCI UYGAR , VAN DELDEN JAY S. , TIWARI SANDIP
Published: July 2007

The works examines the power adaptive control of back-gated planar transistor employing a novel super-self-alignment design. The availability of such back-gate provides additional freedom for the improvement of the transistor performance of higher switching speed and lower power consumption. Both of these two capabilities are investigated through the studies of transistor's output and transfer characteristics.
PROCESS INDEPENDENT MACHINING SIMULATION — A BAR TURNING APPROACH
Authors: LIU EYSION A. , YUAN YIQING , HILL JAMES D. , ZOU QIAN
Published: July 2007

Computer simulation of industrial processes is an important alternative that may be used either to complement or to replace expensive experimental procedures associated with developing new parts or modifying existing process. For a metal cutting process, numerical simulations provide vital information about cutting forces, cutting temperatures, tooling and part distortion, etc. Since the early 1970s, FEA has been applied to simulate machining process. The development of this approach, its assumptions and techniques has been widely accepted. Nowadays, the manufacturing productivity even drives the community to the next level innovation through computer utilizations. A kinematic simulation of machining processes is one of many innovative CAE applications, especially beneficial to high volume production of automotive powertrain parts. In this paper, a generic force calculation method is introduced with a modified horsepower correction factor. An example of sizing milling force, milling paths and proper milling parameters is provided by utilizing the methodology. This paper will also discuss and propose how the manufacturing industry uses this resourceful tool. Applications of the methodology would empower product and manufacturing engineers to make intelligent and cost effective decisions.
HUMAN INTELLIGENCE DIAGNOSIS METHOD UTILIZING ADVANCED TPS
Authors: SAKAI HIROHISA , AMASAKA KAKURO
Published: July 2007

The Japanese manufacturers today are operating for global production strategy. To overcome this, the authors believed it is crucial to improve the intelligence skill level of the production operators who are the foundation of manufacturing. The authors recognized the requirements for 'creating a new production system: "Advanced TPS" that centers around people. As a solution, the authors suggested "HID" (Human Intelligence Diagnosis Method) and assessed its effectiveness at Toyota. More specifically, the authors developed the shortened education system by visualizing skill and implemented the skill training processes for the assembly line operators in order to become more intelligent.
Blebbistatin specifically inhibits actin-myosin interaction in mouse cardiac muscle
Authors: Dou Ying , Arlock Per , Arner Anders
Published: July 2007

Blebbistatin is a powerful inhibitor of actin-myosin interaction in isolated contractile proteins. To examine whether blebbistatin acts in a similar manner in the organized contractile system of striated muscle, the effects of blebbistatin on contraction of cardiac tissue from mouse were studied. The contraction of paced intact papillary muscle preparations and shortening of isolated cardiomyocytes were inhibited by blebbistatin with inhibitory constants in the micromolar range (1.3–2.8 μM). The inhibition constants are similar to those previously reported for isolated cardiac myosin subfragments showing that blebbistatin action is similar in filamentous myosin of the cardiac contractile apparatus and isolated proteins. The inhibition was not associated with alterations in action potential duration or decreased influx through L-type Ca2+ channels. Experiments on permeabilized cardiac muscle preparations showed that the inhibition was not due to alterations in Ca2+ sensitivity of the contractile filaments. The maximal shortening velocity was not affected by 1 μM blebbistatin. In conclusion, we show that blebbistatin is an inhibitor of the actin-myosin interaction in the organized contractile system of cardiac muscle and that its action is not due to effects on the Ca2+ influx and activation systems.
Intestinal phenotype of variable-weight cystic fibrosis knockout mice
Authors: Canale-Zambrano Juan C. , Poffenberger Maya C. , Cory Sean M. , Humes Daryl G. , Haston Christina K.
Published: July 2007

Cystic fibrosis (CF) transmembrane conductance regulator ( Cftr) knockout mice present the clinical features of low body weight and intestinal disease permitting an assessment of the interrelatedness of these phenotypes in a controlled environment. To identify intestinal alterations that are affected by body weight in CF mice, the histological phenotypes of crypt-villus axis height, goblet cell hyperplasia, mast cell infiltrate, crypt cell proliferation, and apoptosis were measured in a population of 12-wk-old (C57BL/6 × BALB/cJ) F2 Cftrtm1UNC and non-CF mice presenting a range of body weight. In addition, cardiac blood samples were assessed, and gene expression profiling of the ileum was completed. Crypt-villus axis height decreased with increasing body weight in CF but not control mice. Intestinal crypts from CF mice had fewer apoptotic cells, per unit length, than did non-CF mice, and normalized cell proliferation was similar to control levels. Goblet cell hyperplasia and mast cell infiltration were increased in the CF intestine and identified to be independent of body weight. Blood triglyceride levels were found to be significantly lower in CF mice than in control mice but were not dependent on CF mouse weight. By expression profiling, genes of DNA replication and lipid metabolism were among those altered in CF mice relative to non-CF controls, and no differences in gene expression were measured between samples from CF mice in the 25th and 75th percentile for weight. In this CF mouse model, crypt elongation, due to an expanded proliferative zone and decreased apoptosis, was identified to be dependent on body weight.
Salmonella entericaserovar Typhimurium regulates intercellular junction proteins and facilitates transepithelial neutrophil and bacterial passage
Authors: Köhler Henrik , Sakaguchi Takanori , Hurley Bryan P. , Kase Benjamin J. , Reinecker Hans-Christian , McCormick Beth A.
Published: July 2007

The establishment of tight junctions (TJ) between columnar epithelial cells defines the functional barrier, which enteroinvasive pathogens have to overcome. Salmonella enterica serovar Typhimurium ( S. typhimurium) directly invades intestinal epithelial cells but it is not well understood how the pathogen is able to overcome the intestinal barrier and gains access to the circulation. Therefore, we sought to determine whether infection with S. typhimurium could regulate the molecular composition of the TJ and, if so, whether these modifications would influence bacterial translocation and polymorphonuclear leukocyte (PMN) movement across model intestinal epithelium. We found that infection of a model intestinal epithelium with S. typhimurium over 2 h resulted in an ∼80% loss of transepithelial electrical resistance. Western blot analysis of epithelial cell lysates demonstrated that S. typhimurium regulated the distribution of the TJ complex proteins claudin-1, zonula occludens (ZO)-2, and E-cadherin in Triton X-100-soluble and insoluble fractions. In addition, S. typhimurium was specifically able to dephosphorylate occludin and degrade ZO-1. This TJ alteration in the epithelial monolayer resulted in 10-fold increase in bacterial translocation and a 75% increase in N-formylmethionin-leucyl-phenyalanine-induced PMN transepithelial migration. Our data demonstrate that infection with S. typhimurium is associated with the rapid targeting of the tight junctional complex and loss of barrier function. This results in enhanced bacterial translocation and initiation of PMN migration across the intestinal barrier. Therefore, the ability to regulate the molecular composition of TJs facilitates the pathogenicity of S. typhimurium by aiding its uptake and distribution within the host.
Retinoblastoma Tumor Suppressor Status Is a Critical Determinant of Therapeutic Response in Prostate Cancer Cells
Authors: Sharma Ankur , Comstock Clay E.S. , Knudsen Erik S. , Cao Khanh H. , Hess-Wilson Janet K. , Morey Lisa M. , Barrera Jason , Knudsen Karen E.
Published: July 2007

The retinoblastoma tumor suppressor protein (RB), a critical mediator of cell cycle progression, is functionally inactivated in the majority of human cancers, including prostatic adenocarcinoma. The importance of RB tumor suppressor function in this disease is evident because 25% to 50% of prostatic adenocarcinomas harbor aberrations in RB pathway. However, no previous studies challenged the consequence of RB inactivation on tumor cell proliferation or therapeutic response. Here, we show that RB depletion facilitates deregulation of specific E2F target genes, but does not confer a significant proliferative advantage in the presence of androgen. However, RB-deficient cells failed to elicit a cytostatic response (compared with RB proficient isogenic controls) when challenged with androgen ablation, AR antagonist, or combined androgen blockade. These data indicate that RB deficiency can facilitate bypass of first-line hormonal therapies used to treat prostate cancer. Given the established effect of RB on DNA damage checkpoints, these studies were then extended to determine the impact of RB depletion on the response to cytotoxic agents used to treat advanced disease. In this context, RB-deficient prostate cancer cells showed enhanced susceptibility to cell death induced by only a selected subset of cytotoxic agents (antimicrotubule agents and a topoisomerase inhibitor). Combined, these data indicate that RB depletion dramatically alters the cellular response to therapeutic intervention in prostate cancer cells and suggest that RB status could potentially be developed as a marker for effectively directing therapy. [Cancer Res 2007;67(13):6192–203]