bluuebunny/crossref_metadata_2025 huggingface dataset:
IL-33: A Sheep in Wolf’s Clothing?
Authors: Gadina Massimo , Jefferies Caroline A.
Published: July 2007

Cytokines are soluble factors that regulate intercellular communication by binding to specific cell-surface receptors and activating cellular responses. A small subset of cytokines, however, has been recognized to act in an intracrine manner without being secreted. These molecules enter the nucleus and regulate gene transcription by binding nuclear coactivators or repressors. Interleukin-33 (IL-33), a cytokine with high sequence and structural similarity to IL-1 and IL-18, has now been identified as another member of this group of "double agents." The activity of IL-33, however, appears to be the opposite of other dual-activity molecules such as the proinflammatory molecules, IL-1α and HMBG1 (high-mobility group box 1). Soluble IL-33 binds the Toll-interleukin 1 (IL-1) receptor (TIR) domain-containing receptor ST2 and has T helper 2 (Th2) immunoregulatory activity. ST2 also inhibits the activity of Toll-like receptors (TLRs) by sequestering the TLR adaptor molecules MyD88 and Mal. The HMBG1 receptor pairs with TLRs and helps drive responses to infections, raising the possibility that ST2, acting as a coreceptor for TLRs, could modulate and perhaps limit immune responses to pathogens. The nuclear targets of IL-33 are still unknown, but the expression of IL-33 in inflamed tissues, its nuclear repressor activity, and the antagonistic properties of ST2 suggest that it could decrease inflammation, opposing the activity of factors like IL-1. If this holds true, IL-33 has potential as a novel therapeutic in autoimmune and inflammatory diseases.
Phospholipid Minds the Gap (Junction)
Authors: Ray L. Bryan
Published: July 2007

Gap junction channels allow communication in the form of small molecules that flow between adjacent cells. Conductance through gap junctions formed of the connexin43 (Cx43) protein is decreased after stimulation of G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors (GPCRs) at the cell surface, but the actual mechanism of channel regulation has been unclear. van Zeijl
et al
. report that in Rat-1 fibroblasts, one way gap junction conductance can be regulated is through changes in the abundance of the phospholipid phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P
2
]. The authors confirmed decreased conductance of gap junctions formed from Cx43 in cells transfected with an active form of the G protein alpha subunit Gα
q
. Gα
q
activates phospholipase C-β (PLC-β), which catalyzes hydrolysis of PtdIns(4,5)P
2
, forming the second messengers inositol 1,4,5-trisphosphate (IP
3
) and diacylglycerol, and experiments with a fluorescently labeled probe containing a pleckstrin homology domain that binds PtdIns(4,5)P
2
revealed that PtdIns(4,5)P
2
was depleted from the plasma membrane in cells expressing the active Gα
q
protein. Depletion of PLC-β3 with RNAi prevented depletion of PtdIns(4,5)P
2
from the plasma membrane in cells treated with GPCR agonists. The communication with the gap junction appeared to require PtdIns(4,5)P
2
itself, rather than IP
3
or DAG, and channel inhibition could be reproduced by depletion of PtdIns(4,5)P
2
with an engineered version of phosphoinositide 5-phosphatase targeted to the plasma membrane. Similarly, overexpression of PtdIns(4)P 5-kinase [to maintain the abundance of PtdIns(4,5)P
2
at the membrane] also prevented receptor-mediated decreases in gap junctional communication. Immunoprecipitation experiments showed that PLC-β3 associated with the scaffold protein ZO-1 (zona occludens 1), and depletion of ZO-1 with RNAi also reduced receptor-mediated regulation of gap junction channels. Thus, the authors propose that ZO-1 helps assemble complexes containing PLC-β3 and Cx43. It’s not altered second messenger production that shuts down the channel but rather the action of PLC-β3 to deplete membrane concentrations of PtdIns(4,5)P
2
, which appears to directly modulate conductance of gap junctions as it does other ion channels and transporters.

L. van Zeijl, B. Ponsioen, B. N. G. Giepmans, A. Ariaens, F. R. Postma , P. Várnai, T. Balla, N. Divecha, K. Jalink, W. H. Moolenaar, Regulation of connexin43 gap junctional communication by phosphatidylinositol 4,5-bisphosphate.
J. Cell Biol.
177
, 881-891 (2007).
[Abstract]
[Full Text]
Double Duty for Rac1 in Epidermal Wound Healing
Authors: DiPersio C. Michael
Published: July 2007

During cutaneous wound healing, increased proliferation and migration of epidermal keratinocytes is essential for efficient re-epithelialization of the wound and restoration of barrier function to the skin. Although numerous cell culture studies have identified intracellular signaling proteins that control proliferation and migration in response to extracellular cues from the wound microenvironment, confirming their importance in wound healing requires appropriate in vivo models. The Rho-family guanosine triphosphatase (GTPase) Rac1 is an effector of cellular responses to growth factors, cytokines, and adhesion proteins present in wounds, and it has long been suspected to be an important regulator of wound healing. Two different genetic models now confirm an essential role for Rac1 in wound healing and, further, identify a dual role for Rac1 in promoting keratinocyte migration and proliferation during wound re-epithelialization. This sets the stage for determining which of the known Rac1 pathways are critical for wound repair in vivo and for linking these pathways to specific integrin or growth factor receptors that mediate cellular responses to cues from the wound environment. Together with studies that implicate Rac1 in maintaining epidermal stem cell populations, these findings lay the foundation for identifying distinct epidermal compartments from which Rac1 controls different aspects of wound re-epithelialization.
Stimulating Neurogenesis to Treat Alzheimer's Disease
Authors: Gough Nancy R.
Published: July 2007

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor that stimulates the proliferation of hematopoietic stem cells and also promotes their release from the bone marrow into the blood. G-CSF has been reported to stimulate the regeneration of nonhematopoietic tissues following damage, such as skeletal muscle, heart, and neurons. Tsai
et al
. found that injected G-CSF improved neurological function in two mouse models of Alzheimer's disease (AD). The AD mice performed better in the Morris water maze test after injection with G-CSF. The neuronal cell death and damage associated with AD involves the formation of plaques containing high concentrations of amyloid β protein (Aβ). Although the concentration of Aβ in the brains was unchanged by G-CSF treatment, there was increased cell proliferation in the areas surrounding the plaques and increased acetylcholine, the neurotransmitter that is decreased in AD brains due to loss of cholinergic neurons. Costaining of the proliferating cells suggested that they were derived from the hematopoietic stem cells. Thus, G-CSF, which is already used clinically to treat neutropenia, may provide additional options for ameliorating the symptoms of AD.

K.-J. Tsai, Y.-C. Tsai, C.-K. J. Shen, G-SCF rescues the memory impairment of animal models of Alzheimer's disease.
J. Exp. Med.
204
, 1273-1280 (2007).
[PubMed]
From Klotho to Calcium
Authors: Ray L. Bryan
Published: July 2007

Klotho, a membrane protein with similarity to glycosidases, has been proposed to modify sugar residues on a TRP channel, to interact with the receptor for fibroblast growth factor 23, and to extend life span when overexpressed. Now Imura
et al.
report that α-Klotho interacts with the α subunit of the Na
+
,K
+
-adenosine triphosphatase (Na
+
,K
+
-ATPase) in mouse cells. The amount of Na
+
,K
+
-ATPase at the plasma membrane appeared to decrease in cells exposed to high concentrations of Ca
2+
, a response that was blunted in cells lacking α-Klotho. The concentration of Ca
2+
in cerebrospinal fluid of mice lacking α-Klotho was slightly lower than that in wild-type animals. Thus, α-Klotho may function in the control of Ca
2+
concentrations by influencing the abundance of the Na
+
,K
+
-ATPase transporter in plasma membranes.

A. Imura, Y. Tsuji, M. Murata, R. Maeda, K. Kubota, A. Iwano, C. Obuse, K. Togashi, M. Tominaga, N. Kita, K. Tomiyama, J. Iijima, Y. Nabeshima, M. Fujioka, R. Asato, S. Tanaka, K. Kojima, J. Ito, K. Nozaki, N. Hashimoto, T. Ito, T. Nishio, T. Uchiyama, T. Fujimori, Y. Nabeshima, α-Klotho as a regulator of calcium homeostasis.
Science
316
, 1615-1618 (2007).
[Abstract]
[Full Text]
A Cell-Free Scintillation Proximity Assay for Studies on Lysosome-to-Phagosome Targeting
Authors: Trivedi Vishal , Zhang Shao Chong , Stockinger Walter , Nohturfft Axel
Published: July 2007

Phagocytes, such as macrophages, neutrophils, and dendritic cells, play important roles in the innate immune system through their ability to engulf, kill, and digest invading microbes. In cooperation with the humoral adaptive immune system, coating of substrates with immunoglobulin G (IgG) antibodies enhances several aspects of phagocytosis, including the recognition of substrates by cell surface IgG (Fcγ) receptors, particle internalization, generation of microbicidal oxygen species, and targeting of lysosomes to phagosomes. We describe a cell-free scintillation proximity assay developed to study the mechanisms of lysosome targeting to phagosomes and the regulation of this process by IgG. The approach involves the use of isolated phagosomes containing scintillant latex beads and lysosomes labeled with a tritiated marker. Scintillation results only when lysosomes and phagosomes come into immediate contact and requires supplementation of reactions with adenosine triphosphate and cytosol; addition of cytosol from IgG-conditioned cells enhances this signal. The method is useful for investigating the biochemistry and regulation of the early tethering and docking steps of lysosome and phagosome interactions.
Getting Inflamed About a Damaged Extracellular Matrix
Authors: Adler Elizabeth M.
Published: July 2007

Inflammation occurs following sterile injuries, as well as in response to microbial infection, and can lead to deleterious effects in various autoimmune diseases. Noting that the glycosaminoglycan hyaluronan (HA, a component of the extracellular matrix) activates Toll-like receptor 4 (TLR4), which is stimulated by the bacterial outer membrane component lipopolysaccharide (LPS) to mobilize elements of the inflammatory response, Taylor
et al
. investigated its role in mediating the inflammatory response to sterile injury. Mice lacking TLR4 produced less of the proinflammatory cytokine MIP-2 (macrophage inflammatory protein 2) than did wild-type mice in two models of sterile injury--subcutaneous injection of beads and localized freezing. Bead injection stimulated a localized increase in HA, and the ability of human wound fluid to stimulate MIP-2 secretion from the MH-S macrophage cell line--which was mimicked by HA but not by chondroitin sulfate or dermatan sulfate--was attenuated by treatment with chondroitinase ABC. Microarray analysis of MH-S cells treated with LPS or HA indicated that, although some genes showed increased expression in response to both treatments [for instance, those encoding interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α)], the responses to these two treatments were distinct. HA and LPS also elicited distinct patterns of cytokine secretion. TLR4-dependent production of IL-8 in response to HA, like TLR4 signaling to LPS, depended on the soluble accessory protein MD-2. However, unlike LPS-dependent signaling, HA signaling through TLR4 did not involve CD14. Rather, HA signaling was enhanced by CD44 (a protein that serves as a receptor for HA and other ligands), which associated with TLR4 and MD-2. Thus, the authors propose that HA released from the extracellular matrix by injury acts through a TLR4 complex distinct from that mediating the inflammatory response to LPS to elicit a distinct inflammatory response.

K. R. Taylor, K. Yamasaki, K. A. Radek, A. Di Nardo, H. Goodarzi, D. Golenbock, B. Beutler, R. L. Gallo, Recognition of hyaluronan released in sterile injury involves a unique receptor complex dependent on Toll-like receptor 4, CD44, and MD-2.
J. Biol. Chem.
282
, 18265-18275 (2007).
[Abstract]
[Full Text]
Morphology Central
Authors: Ray L. Bryan
Published: July 2007

New techniques are enabling systematic characterization of complicated cell regulatory systems. Bakal
et al
. describe a method that allows them to screen for precise morphological changes in cells exposed to one of 249 different conditions of gene overexpression or protein depletion by double-stranded RNA. Analysis of 145 quantitative features allowed clustering techniques to characterize the cellular responses and to map signaling networks that control membrane protrusions, tension on the cell membrane, and cell adhesion.

C. Bakal, J. Aach, G. Church, N. Perrimon, Quantitative morphological signatures define local signaling networks regulating cell morphology.
Science
316
, 1753-1756 (2007).
[Abstract]
[Full Text]
Characterization of the chromosome complement of Helianthus annuus by in situ hybridization of a tandemly repeated DNA sequence
Authors: Ceccarelli M. , Sarri V. , Natali L. , Giordani T. , Cavallini A. , Zuccolo A. , Jurman I. , Morgante M. , Cionini P.G.
Published: July 2007

A tandemly repeated sequence isolated from a clone (HAG004N15) of a nebulized genomic DNA library of sunflower (Helianthus annuus L., 2n = 34) was characterized and used to study the chromosome complement of sunflower. HAG004N15 repeat units (368 bp in length) were found to be highly methylated, and their copy number per haploid (1C) genome was estimated to be 7800. After in situ hybridization of HAG004N15 repeats onto chromosome spreads, signals were observed at the end of both chromosome arms in 4 pairs and at the end of only one arm in 8 other pairs. Signals were also observed at the intercalary (mostly subtelomeric) regions in all pairs, in both arms in 8 pairs, and in only one arm in the other 9 pairs. The short arm of 1 pair was labelled entirely. The chromosomal location of ribosomal DNA was also studied by hybridizing the wheat ribosomal probe pTa71. Four chromosome pairs contained ribosomal cistrons at the end of their shorter arm, but a satellite was seen in only 3 pairs. These hybridization patterns were the same in the 3 sunflower lines studied (HA89, RA20031, and HOR). The chromosomal localization of HAG004N15-related sequences allowed all of the chromosome pairs to be distinguished from each other, in spite of small size and similar morphology.
Retrotransposon-based markers from potato monoploids used in somatic hybridization
Authors: Lightbourn Gordon J. , Jelesko John G. , Veilleux Richard E.
Published: July 2007

In an attempt to remove lethal and deleterious genes and enhance the heterozygosity of the potato genome, we developed several diverse somatic hybrids through the electrofusion of selected monoploids. Somatic hybrids and somaclones resulting from fused and unfused protoplasts, respectively, were verified with microsatellites. Molecular markers anchored in the Tst1 retrotransposon were used to examine polymorphisms in the regenerated plants and to reveal any somaclonal variation. Inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon display (sequence-specific amplified polymorphism (S-SAP), anchored in a retransposon) were examined on an ALFexpress DNA sequencer. Because of inconsistencies in the number and quality of bands revealed by the combination of either class of marker in combination with the ALFexpress, we cloned and sequenced 11 S-SAP bands to use as restriction fragment length polymorphism (RFLP) probes in Southern blot analyses of genetic relationships in our potato populations and among related Solanaceae. Readily scorable bands (n = 27) that separated somatic hybrids from parental monoploids and somaclones and grouped monoploids according to known genetic relationships were produced. Some of the probes could be used to differentiate tomato and Datura from potato. Sequence analysis of 5 cloned IRAP and 11 cloned S-SAP markers confirmed that they were anchored in the Tst1 retrotransposon. BLAST searches within GenBank produced 10 highly significant hits (5 nucleotide, 4 expressed sequence tag (EST), and 1 protein) within closely related Solanaceae, suggesting that Tst1 represents an old retroelement that was inserted before the diversion of genera within Solanaceae; however, most sequences were undescribed.
Mitochondrial membrane fluidity, potential, and calcium transients in the myocardium from acute diabetic ratsThis 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: Waczulikova Iveta , Habodaszova Dana , Cagalinec Michal , Ferko Miroslav , Ulicna Olga , Mateasik Anton , Sikurova Libusa , Ziegelhöffer Attila
Published: July 2007

In this study, we report for the first time concurrent measurements of membrane potential and dynamics and respiratory chain activities in rat heart mitochondria, as well as calcium transients in the hearts of rats in an early phase of streptozotocin diabetes, not yet accompanied with diabetes-induced complications. Quantitative relationships among these variables were assessed. The mitochondria from diabetic rats exhibited decreased fluorescence anisotropy values of diphenylhexatriene. This indicates that hydrophobic core of the membranes was more fluid compared with controls (p < 0.05). We discuss the changes in fluidity as having been associated with augmented energy transduction through the diabetic membranes. Reduced ratio of JC-1 fluorescence (aggregates to monomers) in the mitochondria from diabetic hearts reflected descendent transmembrane potential. A significant negative association between membrane fluidity and potential in the diabetic group was found (p < 0.05; r = 0.67). Further, we observed an increase in calcium transient amplitude (CTA) in the diabetic cardiomyocytes (p = 0.048). We conclude that some of the calcium-induced regulatory events that dictate fuel selection and capacity for ATP production in diabetic heart occur at the membrane level. Our findings offer new insight into acute diabetes-induced changes in cardiac mitochondria.
A GAN ON SIC HFET DEVICE TECHNOLOGY FOR WIRELESS INFRASTRUCTURE APPLICATIONS
Authors: Green B. , Henry H. , Moore K. , Abdou J. , Lawrence R. , Clayton F. , Miller M. , Crowder J. , Mares E. , Hartin O. , Liu C. , Weitzel C.
Published: July 2007

This paper presents Freescale's baseline GaN device technology for wireless infrastructure applications. At 48 V drain bias and 2.1 GHz operating frequency 10-11 W/mm, 62-67% power-added efficiency (PAE) is realized on 0.3 mm devices and 74 W (5.9 W/mm), 55% PAE is demonstrated for 12.6 mm devices. A simple thermal model shows that a more than twofold increase in channel temperature is responsible for limiting the CW power density on the 12.6 mm compared to 0.3 mm devices. The addition of through wafer source vias to improve gain and tuning the device in a fixture optimized for efficiency yield an output power of 57W (4.7 W/mm), PAE of 66%, and a calculated channel temperature of approximately 137°C at a 28 V bias.
Drift Velocity Limitation in GaN HEMT Channels
Authors: MATULIONIS ARVYDAS
Published: July 2007

Additional friction due to Pauli constraint, channel self-heating, alloy scattering, and hot phonons is reconsidered.
SELF-INDUCED SURFACE TEXTURING OF Al2O3 BY MEANS OF INDUCTIVELY COUPLED PLASMA REACTIVE ION ETCHING IN CL2 CHEMISTRY
Authors: BATONI PAOLO , STOKES EDWARD B. , SHAH TRUSHANT K. , HODGE MICHAEL D. , SULESKI THOMAS J.
Published: July 2007

In this work we investigate a pseudo-random surface texturing technique of sapphire by means of inductively coupled plasma reacting ion etching in chlorine chemistry, for which no sophisticated lithographic process is required. Such a surface texturing technique, which we believe offers indicative promise for enhanced light extraction in deep ultraviolet light-emitting diodes has allowed us to texture sapphire samples having a surface larger than 1 cm2 with controlled structures. Fabrication parameters have been characterized, and textured Al 2 O 3 surfaces having submicron features, and nano-scale periodicity have been obtained. Performance, and characterization of our textured Al 2 O 3 surfaces is the hinge of addition work in progress.
A MIXED-SIGNAL ROW/COLUMN ARCHITECTURE FOR VERY LARGE MONOLITHIC mm-WAVE PHASED ARRAYS
Authors: CARTA CORRADO , SEO MUNKYO , RODWELL MARK
Published: July 2007

The range of mm-wave radio communications is severely constrained by high losses arising from the short wavelength and from atmospheric attenuation. Large phased arrays can overcome these limitations, but it is very difficult to realize them using present monolithic beamsteering IC architectures. We propose an alternative architecture for large monolithic phased arrays. The beam is steered in altitude and in azimuth by separately imposing vertical and horizontal phase gradients. This choice reduces IC complexity, making large arrays feasible. Since extensive digital processing provides robust amplitude control and reduces die area, the LOs are processed as digital signals. Being very sensitive to compression, the IF signals are processed as analog signals and distributed by means of synthetic transmission-line buses. With careful frequency planning, this mixed-signal approach can allow large phased arrays to operate at frequencies much higher than those achievable with pure analog design.
AN OBJECT-ORIENTED FUZZY CONTROLLER FOR DYNAMIC SEQUENCING OF FLEXIBLE MACHINES
Authors: CAPRIHAN RAHUL , KUMAR SATISH , GURSARAN  , DAS ANKUR
Published: July 2007

Most real world manufacturing systems operate under conditions that entail significant information delays. Hence, there is a need to model, analyze and evolve control strategies that can perform well under such delays. This paper introduces a fuzzy associative memory-based control strategy, the generalised fuzzy sequencing strategy (GFSS), to cope with status information delays. In demonstrating the use of GFSS for the single machine, three queue dynamic sequencing problem wherein information delays manifest in the form of machine setup times, the paper identifies suitable input and output control variables and suggests their appropriate fuzzification. We define the relative work-in-process, relative setup time, relative service rate, and relative traffic intensity as four input fuzzy control variables. The output fuzzy variable is the queue confidence level. Using the input and output fuzzy variables, the design of GFSS is described together with its implementation in an object-oriented environment. Simulation results for the average part flowtime and average work-in-process level performance measures demonstrate the efficacy and potential of using fuzzy control in situations where machine setup times are significant. Importantly, although designed for the three-queue single-machine dynamic sequencing problem, GFSS is generalizable for the n-queue case in a straightforward manner.
Genetics of Candida albicans, a Diploid Human Fungal Pathogen
Authors: Noble Suzanne M. , Johnson Alexander D.
Published: July 2007

Candida albicans is a species of fungus that typically resides in the gastrointestinal tracts of humans and other warm-blooded animals. It is also the most common human fungal pathogen, causing a variety of skin and soft tissue infections in healthy people and more virulent invasive and disseminated diseases in patients with compromised immune systems. How this microorganism manages to persist in healthy hosts but also to cause a spectrum of disease states in the immunocompromised host are questions of significant biological interest as well as major clinical and economic importance. In this review, we describe recent developments in population genetics, the mating process, and gene disruption technology that are providing much needed experimental insights into the biology of C. albicans.
Searching for New Physics inb→sHadronic Penguin Decays
Authors: Silvestrini Luca
Published: July 2007

We review the theoretical status of b → s hadronic penguin decays in the Standard Model and beyond. We summarize the main theoretical tools to compute branching ratios and CP asymmetries for b → s penguin-dominated nonleptonic decays and discuss the theoretical uncertainties in the prediction of time-dependent CP asymmetries in these processes. We consider general aspects of b → s transitions beyond the Standard Model. Then we present detailed predictions in supersymmetric models with new sources of flavor and CP violation.
Amiloride-sensitive Na+ channels contribute to regulatory volume increases in human glioma cells
Authors: Ross Sandra B. , Fuller Catherine M. , Bubien James K. , Benos Dale J.
Published: July 2007

Despite intensive research, brain tumors remain among the most difficult type of malignancies to treat, due largely to their diffusely invasive nature and the associated difficulty of adequate surgical resection. To migrate through the brain parenchyma and to proliferate, glioma cells must be capable of significant changes in shape and volume. We have previously reported that glioma cells express an amiloride- and psalmotoxin-sensitive cation conductance that is not found in normal human astrocytes. In the present study, we investigated the potential role of this ion channel to mediate regulatory volume increase in glioma cells. We found that the ability of the cells to volume regulate subsequent to cell shrinkage by hyperosmolar solutions was abolished by both amiloride and psalmotoxin 1. This toxin is thought to be a specific peptide inhibitor of acid-sensing ion channel (ASIC1), a member of the Deg/ENaC superfamily of cation channels. We have previously shown this toxin to be an effective blocker of the glioma cation conductance. Our data suggest that one potential role for this conductance may be to restore cell volume during the cell's progression thorough the cell cycle and while the tumor cell migrates within the interstices of the brain.
Upregulation of IL-6 mRNA by IL-6 in skeletal muscle cells: role of IL-6 mRNA stabilization and Ca2+-dependent mechanisms
Authors: Weigert Cora , Düfer Martina , Simon Perikles , Debre Evaine , Runge Heike , Brodbeck Katrin , Häring Hans U. , Schleicher Erwin D.
Published: July 2007

Skeletal muscle cells have been established as significant producers of IL-6 during exercise. This IL-6 production is discussed as one possible mediator of the beneficial effects of physical activity on glucose and fatty acid metabolism. IL-6 itself could be the exercise-related factor that upregulates and maintains its own production. We investigated this hypothesis and the underlying molecular mechanism in cultured C2C12 cells. IL-6 led to a rapid and prolonged increase in IL-6 mRNA, which was also found in human myotubes. Because IL-6 has been shown to activate AMP-activated kinase (AMPK), we studied whether, in turn, activated AMPK induces IL-6 expression. Pharmacological activation of AMPK with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside upregulated IL-6 mRNA expression, which was blocked by knockdown of AMPK α1 and α2 using small, interfering RNA (siRNA) oligonucleotides. However, the effect of IL-6 was shown to be independent of AMPK, since the siRNA approach silencing the AMPK α-subunits did not reduce the upregulation of IL-6 induced by IL-6 stimulation. The self-stimulatory effect of IL-6 partly involves a Ca2+-dependent pathway: IL-6 increased intracellular Ca2+, and intracellular blockade of Ca2+ with a Ca2+ chelator reduced the IL-6-mediated increase in IL-6 mRNA levels. Moreover, inhibition of Ca2+/calmodulin-dependent kinase kinase with STO-609 or the siRNA approach decreased IL-6 mRNA levels of control and IL-6-stimulated cells. A major, STO-609-independent mechanism is the IL-6-mediated stabilization of its mRNA. The data suggest that IL-6 could act as autocrine factor upregulating its mRNA levels, thereby supporting its function as an exercise-activated factor in skeletal muscle cells.
Contributions of collision rate and collision efficiency to erythrocyte aggregation in postcapillary venules at low flow rates
Authors: Kim Sangho , Zhen Janet , Popel Aleksander S. , Intaglietta Marcos , Johnson Paul C.
Published: July 2007

Red blood cell aggregation at low flow rates increases venous vascular resistance, but the process of aggregate formation in these vessels is not well understood. We previously reported that aggregate formation in postcapillary venules of the rat spinotrapezius muscle mainly occurs in a middle region between 15 and 30 μm downstream from the entrance. In light of the findings in that study, the main purpose of this study was to test two hypotheses by measuring collision frequency along the length of the venules during low flow. We tested the hypothesis that aggregation rarely occurs in the initial 15-μm region of the venule because collision frequency is very low. We found that collision frequency was lower than in other regions, but collision efficiency (the ratio of aggregate formation to collisions) was almost nil in this region, most likely because of entrance effects and time required for aggregation. Radial migration of red blood cells and Dextran 500 had no effect on collision frequency. We also tested the hypothesis that aggregation was reduced in the distal venule region because of the low aggregability of remaining nonaggregated cells. Our findings support this hypothesis, since a simple model based on the ratio of aggregatable to nonaggregatable red blood cells predicts the time course of collision efficiency in this region. Collision efficiency averaged 18% overall but varied from 0 to 52% and was highest in the middle region. We conclude that while collision frequency influences red blood cell aggregate formation in postcapillary venules, collision efficiency is more important.
Energy substrate utilization during prolonged exercise with and without carbohydrate intake in preadolescent and adolescent girls
Authors: Timmons Brian W. , Bar-Or Oded , Riddell Michael C.
Published: July 2007

Little information is available on energy metabolism during exercise in girls, particularly the contribution of exogenous carbohydrate (CHOexo). The purpose of this study was to determine substrate utilization during exercise with and without CHOexo intake in healthy girls. Twelve-yr-old preadolescent (YG; n = 12) and 14-yr-old adolescent (OG; n = 10) girls consumed flavored water (WT) or 13C-enriched 6% CHO (CT) while cycling for 60 min at ∼70% maximal aerobic power (V̇o2max). Substrate utilization was calculated for the final 15 min of exercise. CHOexo decreased fat oxidation by ∼50% in YG but not in OG ( P < 0.001) and decreased endogenous CHO oxidation by ∼15% in OG but not in YG ( P = 0.006). Endogenous CHO oxidation was lower in YG than in OG regardless of trial ( P ≤ 0.01), whereas fat oxidation was higher in YG only during WT ( P < 0.001). CHOexo oxidation rate was similar between YG and OG (7.1 ± 0.5 and 6.8 ± 0.4 mg·kg−1·min−1, respectively, P = 0.67), contributing ∼19% to total energy expenditure. Serum estradiol levels in all girls correlated with fat ( r = −0.50 to −0.59, P = 0.03 to 0.005) and endogenous CHO oxidation ( r = 0.50 to 0.63, P = 0.03 to 0.005) but not with CHOexo oxidation ( r = −0.09, P = 0.71). We conclude that CHOexo influences endogenous substrate utilization in an age-dependent manner in healthy girls but that total CHOexo oxidation during exercise is not different between YG and OG. Our results also point to potential sex-related differences in energy substrate utilization even during childhood.
Effect of heat acclimation on heat shock protein 72 and interleukin-10 in humans
Authors: Yamada Paulette M. , Amorim Fabiano T. , Moseley Pope , Robergs Robert , Schneider Suzanne M.
Published: July 2007

Heat acclimation (HA) results in whole body adaptations that increase heat tolerance, and in addition, HA may also result in protective cellular adaptations. We hypothesized that, after HA, basal intracellular heat shock protein (HSP) 72 and extracellular IL-10 levels would increase, while extracellular HSP72 levels decrease. Ten male and two female subjects completed a 10-day exercise/HA protocol (100-min exercise bout at 56% of maximum O2uptake in a 42.5°C DB, 27.9% RH environment); subjects exhibited classic adaptations that accompany HA. Peripheral blood mononuclear cells (PBMCs) were isolated before and after each acclimation session on days 1, 6, and 10; plasma and serum were collected before and after exercise on the 1st and 10th day of HA. SDS-PAGE was used to determine PBMC HSP72 levels during HA, and ELISA was used to measure plasma IL-10 and serum HSP72 concentrations. The increase in PBMC HSP72 from pre- to postexercise on the 1st day of HA was not significant (mean ± SD, 1.0 ± 0 vs. 1.6 ± 0.6 density units). Preexercise HSP72 levels on day 1 were significantly lower compared with the pre- and postexercise samples on days 6 and 10 (mean ± SD, day 6: 2.1 ± 1.0 and 2.2 ± 1.0, day 10: 2.0 ± 1.3 and 2.2 ± 1.0 density units, respectively, P < 0.05). There were no differences in plasma IL-10 and serum HSP72 postexercise or after 10 days of HA. The sustained elevation of HSP72 from days 6 to 10 may be evidence of a cellular adaptation to HA that contributes to improved heat tolerance and reduced heat illness risk.
Linear Responses to Stochastic Motion Signals in Area MST
Authors: Heuer Hilary W. , Britten Kenneth H.
Published: July 2007

The medial superior temporal (MST) area contains neurons with tuning for complex motion patterns, but very little is known about the generation of such responses. To explore how neuronal responses varied across complex motion pattern coherence, we recorded from single units while varying the strength of the global motion pattern in random dot stimuli. Stimuli were a family of optic flow patterns, consisting of radial motion, rotary motion, or combinations thereof (“spiral space”). We controlled the strength of the motion in the stimuli by varying the coherence—the proportion of dots carrying the signal. This allows motion strength to be varied independently of stimulus size, speed, or contrast. Most neurons’ responses were well described as a linear function of stimulus coherence. Although more than half the cells possessed significant nonlinearities, these typically accounted for little additional variance. Nonlinear coherence response functions could either be compressive (e.g., saturating) or expansive and occurred in both the preferred and null direction responses. The presence of nonlinearities was not related to neuronal response properties such as preferred spiral-space direction or tuning bandwidth; however, cells with compressive nonlinearities in both the preferred and null directions tended to have higher response amplitudes and were more sensitive to weak motion signals. These cells did not appear to form a distinct subpopulation within MST. Our results suggest that MST neurons predominantly linearly encode increasing pattern motion energy within their RFs.
Endomorphin-1 Modulates Intrinsic Inhibition in the Dorsal Vagal Complex
Authors: Glatzer Nicholas R. , Derbenev Andrei V. , Banfield Bruce W. , Smith Bret N.
Published: July 2007

Mu-opioid receptor (MOR) agonists profoundly influence digestive and other autonomic functions by modulating neurons in nucleus tractus solitarius (NTS) and dorsal motor nucleus of the vagus (DMV). Whole cell recordings were made from NTS and DMV neurons in brain stem slices from rats and transgenic mice that expressed enhanced green fluorescent protein (EGFP) under the control of a GAD67 promoter (EGFP-GABA neurons) to identify opioid-mediated effects on GABAergic circuitry. Synaptic and membrane properties of EGFP-GABA neurons were assessed. The endogenous selective MOR agonist endomorphin-1 (EM-1) reduced spontaneous and evoked excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs) in both rat and mouse DMV neurons. Electrical stimulation of the solitary tract evoked constant-latency EPSCs in ∼50% of EGFP-GABA neurons, and the responses were reduced by EM-1 application. EM-1 reduced action potential firing, the frequency and amplitude of synaptic inputs in EGFP-GABA neurons and responses to direct glutamate stimulation. A subset of EGFP-GABA neurons colocalized mRFP1 after retrograde, transneuronal infection after gastric inoculation with PRV-614, indicating that they synapsed with gastric-projecting DMV neurons. Glutamate photolysis stimulation of intact NTS projections evoked IPSCs in DMV neurons, and EM-1 reduced the evoked response, most likely by activation of MOR on the soma of premotor GABA neurons in NTS. Naltrexone or H-d-Phe-Cys-Tyr-d-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP), MOR antagonists, blocked the effects of EM-1. Our results show that GABA neurons in the NTS receive direct vagal afferent input and project to gastric-related DMV neurons. Furthermore, modulation by EM-1 of specific components of the vagal complex differentially suppresses excitatory and inhibitory synaptic input to the DMV by acting at different receptor locations.
Effect of Nicotine on Chorda Tympani Responses to Salty and Sour Stimuli
Authors: Lyall Vijay , Phan Tam-Hao T. , Mummalaneni Shobha , Mansouri Mahdis , Heck Gerard L. , Kobal Gerd , DeSimone John A.
Published: July 2007

The effect of nicotine on the benzamil (Bz)-insensitive (transient receptor potential vanilloid-1 variant cation channel, TRPV1t) and the Bz-sensitive (epithelial Na+ channel, ENaC) salt taste receptors and sour taste was investigated by monitoring intracellular Na+ and H+ activity (pHi) in polarized fungiform taste receptor cells (TRCs) and the chorda tympani (CT) nerve responses to NaCl, KCl, and HCl. CT responses in Sprague–Dawley rats and both wildtype and TRPV1 knockout (KO) mice were recorded in the presence and absence of agonists [resiniferatoxin (RTX) and elevated temperature] and an antagonist (SB-366791) of TRPV1t, the ENaC blocker (Bz), and varying apical pH (pHo). At concentrations <0.015 M, nicotine enhanced and at >0.015 M, it inhibited CT responses to KCl and NaCl. Nicotine produced maximum enhancement in the Bz-insensitive NaCl CT response at pHo between 6 and 7. RTX and elevated temperature increased the sensitivity of the CT response to nicotine in salt-containing media, and SB-366791 inhibited these effects. TRPV1 KO mice demonstrated no Bz-insensitive CT response to NaCl and no sensitivity to nicotine, RTX, and elevated temperature. We conclude that nicotine modulates salt responses by direct interaction with TRPV1t. At pHo >8, the apical membrane permeability of nicotine was increased significantly, resulting in increase in TRC pHi and volume, activation of ENaC, and enhancement of the Bz-sensitive NaCl CT response. At pHo >8, nicotine also inhibited the phasic component of the HCl CT response. We conclude that the effects of nicotine on ENaC and the phasic HCl CT response arise from increases in TRC pHi and volume.
Experimentally Valid Predictions of Muscle Force and EMG in Models of Motor-Unit Function Are Most Sensitive to Neural Properties
Authors: Keenan Kevin G. , Valero-Cuevas Francisco J.
Published: July 2007

Computational models of motor-unit populations are the objective implementations of the hypothesized mechanisms by which neural and muscle properties give rise to electromyograms (EMGs) and force. However, the variability/uncertainty of the parameters used in these models—and how they affect predictions—confounds assessing these hypothesized mechanisms. We perform a large-scale computational sensitivity analysis on the state-of-the-art computational model of surface EMG, force, and force variability by combining a comprehensive review of published experimental data with Monte Carlo simulations. To exhaustively explore model performance and robustness, we ran numerous iterative simulations each using a random set of values for nine commonly measured motor neuron and muscle parameters. Parameter values were sampled across their reported experimental ranges. Convergence after 439 simulations found that only 3 simulations met our two fitness criteria: approximating the well-established experimental relations for the scaling of EMG amplitude and force variability with mean force. An additional 424 simulations preferentially sampling the neighborhood of those 3 valid simulations converged to reveal 65 additional sets of parameter values for which the model predictions approximate the experimentally known relations. We find the model is not sensitive to muscle properties but very sensitive to several motor neuron properties—especially peak discharge rates and recruitment ranges. Therefore to advance our understanding of EMG and muscle force, it is critical to evaluate the hypothesized neural mechanisms as implemented in today's state-of-the-art models of motor unit function. We discuss experimental and analytical avenues to do so as well as new features that may be added in future implementations of motor-unit models to improve their experimental validity.
Preferential Expression of Very Late Antigen-4 on Type 1 CTL Cells Plays a Critical Role in Trafficking into Central Nervous System Tumors
Authors: Sasaki Kotaro , Zhu Xinmei , Vasquez Cecilia , Nishimura Fumihiko , Dusak Jill E. , Huang Jian , Fujita Mitsugu , Wesa Amy , Potter Douglas M. , Walker Paul R. , Storkus Walter J. , Okada Hideho
Published: July 2007

We have previously shown preferential tumor-homing and therapeutic efficacy of adoptively transferred type 1 CTL (Tc1) when compared with type 2 CTL (Tc2) in mice bearing intracranial ovalbumin-transfected melanoma (M05). Further characterizing the expression of a panel of homing receptors on Tc1 and Tc2 cells, we found that very late antigen (VLA)-4 (a heterodimer of CD49d and CD29), but none of other receptors evaluated, was expressed at significantly higher levels on Tc1 cells than on Tc2 cells. Although CD49d (α4 integrin) can form heterodimers with both β1 (CD29) and β7 integrins, α4β7 complexes were not expressed by either Tc1 or Tc2 cells, suggesting that CD49d is solely expressed in VLA-4 complexes. VLA-4 expression on Tc2 cells was down-regulated in an interleukin (IL)-4 dose-dependent manner but not by other type 2 cytokines, such as IL-10 and IL-13, suggesting that IL-4 uniquely down-regulates VLA-4 expression on these cells. In accordance with the differential expression of VLA-4 on Tc1 versus Tc2 cells, Tc1 cells alone were competent to adhere to plate-bound VCAM-1-Ig fusion protein. Finally, the efficient trafficking of Tc1 cells into intracranial M05 lesions in vivo was efficiently blocked by administration of monoclonal antibodies against CD49d or VCAM-1 or small interfering RNA–mediated silencing of CD49d on Tc1 cells. Collectively, these data support the critical role of VLA-4 in the effective intracranial tumor homing of adoptive-transferred, antigen-specific Tc1 cells and suggest that more effective vaccine and/or ex vivo T-cell activation regimens may be developed by promoting the generation of VLA-4+ antitumor Tc1 cells. [Cancer Res 2007;67(13):6451–8]
Podocalyxin Increases the Aggressive Phenotype of Breast and Prostate Cancer Cells In vitro through Its Interaction with Ezrin
Authors: Sizemore Steven , Cicek Muzaffer , Sizemore Nywana , Ng Kwok Peng , Casey Graham
Published: July 2007

Podocalyxin is an anti-adhesive transmembrane sialomucin that has been implicated in the development of more aggressive forms of breast and prostate cancer. The mechanism through which podocalyxin increases cancer aggressiveness remains poorly understood but may involve the interaction of podocalyxin with ezrin, an established mediator of metastasis. Here, we show that overexpression of podocalyxin in MCF7 breast cancer and PC3 prostate cancer cell lines increased their in vitro invasive and migratory potential and led to increased expression of matrix metalloproteases 1 and 9 (MMP1 and MMP9). Podocalyxin expression also led to an increase in mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) activity. To determine the role of ezrin in these podocalyxin-dependent phenotypic events, we first confirmed that podocalyxin formed a complex with ezrin in MCF7 and PC3 cells. Furthermore, expression of podocalyxin was associated with a changed ezrin subcellular localization and increased ezrin phosphorylation. Transient knockdown of ezrin protein abrogated MAPK and PI3K signaling as well as MMP expression and invasiveness in cancer cells overexpressing podocalyxin. These findings suggest that podocalyxin leads to increased in vitro migration and invasion, increased MMP expression, and increased activation of MAPK and PI3K activity in MCF7 and PC3 cells through its ability to form a complex with ezrin. [Cancer Res 2007;67(13):6183–91]
Tumor Suppressor 101F6 and Ascorbate Synergistically and Selectively Inhibit Non–Small Cell Lung Cancer Growth by Caspase-Independent Apoptosis and Autophagy
Authors: Ohtani Shoichiro , Iwamaru Arifumi , Deng Wuguo , Ueda Kentaro , Wu Guanglin , Jayachandran Gitanjali , Kondo Seiji , Atkinson Edward N. , Minna John D. , Roth Jack A. , Ji Lin
Published: July 2007

101F6 is a candidate tumor suppressor gene harbored on chromosome 3p21.3, a region with frequent and early allele loss and genetic alterations in many human cancers. We previously showed that enforced expression of wild-type 101F6 by adenoviral vector–mediated gene transfer significantly inhibited tumor cell growth in 3p21.3-deficient non–small cell lung cancer (NSCLC) cells in vitro and in vivo. The molecular mechanism of 101F6-mediated tumor suppression is largely unknown. A computer-aided structural and functional model predicts the 101F6 protein to be a member of the cytochrome b561 protein family that is involved in the regeneration of the antioxidant ascorbate. 101F6 protein is expressed in normal lung bronchial epithelial cells and fibroblasts but is lost in most lung cancers. Treatment with 101F6 nanoparticle–mediated gene transfer in combination with a subpharmacologic dose (200–500 μmol/L) of ascorbate synergistically and selectively inhibited lung cancer cell growth in vitro. Systemic injection of 101F6 nanoparticles plus the i.p. injection of ascorbate synergistically inhibited both tumor formation and growth in human NSCLC H322 orthotopic lung cancer mouse models (P < 0.001). Furthermore, exogenous expression of 101F6 enhanced intracellular uptake of ascorbate, leading to an accumulation of cytotoxic H2O2 and a synergistic killing of tumor cells through caspase-independent apoptotic and autophagic pathways. The antitumor synergism showed by the combination treatment with systemic administration of 101F6 nanoparticles and ascorbate on lung cancer offers an attractive therapeutic strategy for future clinical trials in cancer prevention and treatment. [Cancer Res 2007;67(13):6293–303]