bluuebunny/crossref_metadata_2025 huggingface dataset:
Addressable adsorption of lipid vesicles and subsequent protein interaction studies
Authors: Klenkar Goran , Brian Björn , Ederth Thomas , Stengel Gudrun , Höök Fredrik , Piehler Jacob , Liedberg Bo
Published: January 2009

We demonstrate a convenient chip platform for the addressable immobilization of protein-loaded vesicles on a microarray for parallelized, high-throughput analysis of lipid-protein systems. Self-sorting of the vesicles on the microarray was achieved through DNA bar coding of the vesicles and their hybridization to complementary strands, which are preimmobilized in defined array positions on the chip. Imaging surface plasmon resonance in ellipsometric mode was used to monitor vesicle immobilization, protein tethering, protein-protein interactions, and chip regeneration. The immobilization strategy proved highly specific and stable and presents a mild method for the anchoring of vesicles to predefined areas of a surface, while unspecific adsorption to both noncomplementary regions and background areas is nonexistent or, alternatively, undetectable. Furthermore, histidine-tagged receptors have been stably and functionally immobilized via bis-nitrilotriacetic acid chelators already present in the vesicle membranes. It was discovered though that online loading of proteins to immobilized vesicles leads to cross contamination of previously loaded vesicles and that it was necessary to load the vesicles offline in order to obtain pure protein populations on the vesicles. We have used this cross-binding effect to our benefit by coimmobilizing two receptor subunits in different ratios on the vesicle surface and successfully demonstrated ternary complex formation with their ligand. This approach is suitable for mechanistic studies of complex multicomponent analyses involving membrane-bound systems.
Fluctuations and destabilization of single phospholipid bilayers
Authors: Charitat T. , Lecuyer S. , Fragneto G.
Published: January 2009

Supported phospholipid bilayers are interesting model systems for biologists and present fascinating physical properties. The authors present an extensive experimental study of the dynamic properties of supported bilayers. The structure and the equilibrium properties of single and double supported bilayers were investigated with neutron reflectivity. The submicronic fluctuation spectrum of a nearly free “floating” bilayer was determined using off-specular x-ray scattering: the surface tension of the bilayer, its bending modulus, and the intermembrane potential could be determined. Using fluorescence microscopy, the authors showed that this well-controlled single bilayer can form vesicles. Destabilization occurred either at the main gel-fluid transition of the lipids and could be interpreted in terms of a decrease in the bending rigidity or under an ac low-frequency electric field applied in the fluid phase. In the latter case, the authors also studied the effect of the electric field at the molecular length scale by neutron reflectivity. In both cases, destabilization leads to the formation of relatively monodisperse vesicles. This could give further understanding on the vesicle formation mechanism and on the parameters that determine the vesicle size.
Molecular simulation of protein-surface interactions: Benefits, problems, solutions, and future directions (Review)
Authors: Latour Robert A.
Published: January 2009

While the importance of protein adsorption to materials surfaces is widely recognized, little is understood at this time regarding how to design surfaces to control protein adsorption behavior. All-atom empirical force field molecular simulation methods have enormous potential to address this problem by providing an approach to directly investigate the adsorption behavior of peptides and proteins at the atomic level. As with any type of technology, however, these methods must be appropriately developed and applied if they are to provide realistic and useful results. Three issues that are particularly important for the accurate simulation of protein adsorption behavior are the selection of a valid force field to represent the atomic-level interactions involved, the accurate representation of solvation effects, and system sampling. In this article, each of these areas is addressed and future directions for continued development are presented.
Interfacial adsorption and denaturization of human milk and recombinant rice lactoferrin
Authors: Pan Fang , Zhao XiuBo , Waigh Thomas A. , Lu Jian R. , Miano Fausto
Published: January 2009

Lactoferrin (LF) produced from recombinant technologies can achieve almost identical amino acid sequences and three-dimensional structures to those extracted from mammals, but differences often arise in the carbohydrate chains attached through N-glycosylation, with altered sizes, structures, and chemical nature. We compare the differences in solvation and interfacial adsorption from two samples, human milk lactoferrin (hLF) and recombinant rice lactoferrin (rLF). Lactoferrin is a bilobal protein with a molecular weight of about 80 kD. It has three N-glycosylation sites. Each of the three attached glycan chains on rLF contains seven to eight sugar groups. In comparison, each of the three glycan chains attached to hLF contains 12–13 sugar groups and is twice as long. The rLF meting point in 1 mg/ml aqueous solution (pH 7 phosphate buffer, I=20 mM was 43 °C from dynamic light scattering, compared to 53 °C for hLF, exhibiting the enhanced solvation and stability of hLF due to its longer carbohydrate side chains. Silicon oxide surfaces provided a model substrate for assessment of lactoferrin adsorption and comparison with other proteins. The time dependent interfacial adsorption studied by spectroscopic ellipsometry (SE) was characterized by a fast initial step followed by a slow relaxation process. In addition, the SE results revealed the persistently higher adsorption of rLF, again showing the effect of glycan side chains. In spite of the different adsorbed amounts, neutron reflection revealed similar interfacial structures of the adsorbed protein layers. At the low lactoferrin concentration around 10 mg/l, a flat-on molecular monolayer formed with both LF lobes attached to the SiO2 surface through electrostatic attraction. As the protein concentration increased, a secondary molecular layer further adsorbed to the first one and the attachment was again driven by electrostatic attraction. The intermixing between the globular lobes resulted in the dense packing in the middle 60 Å with some of the lobes projected toward the aqueous bulk solution.
Solid supported multicomponent lipid membranes studied by x-ray spectromicroscopy
Authors: Nováková Eva , Mitrea Genoveva , Peth Christian , Thieme Jürgen , Mann Klaus , Salditt Tim
Published: January 2009

This article addresses the lateral organization of two-component lipid membranes deposited on a solid support with the addition of colloidal particles. The authors have applied synchrotron-based scanning transmission soft x-ray spectromicroscopy to image thin lipid layer patches with bound microspheres coated by a charged monolayer. The ability and current limits of scanning transmission x-ray spectromicroscopy to examine samples under physiologically relevant conditions in the presence of excess water have been tested. In particular, the authors have investigated a range of model lipids and have shown that these can be reproducibly identified from the near-edge x-ray absorption fine structure spectra at the carbon K absorption edge. Reference spectra were obtained based on a compact laser-driven plasma source, while the spectromicroscopy data were collected using synchrotron radiation at a lateral resolution of about 60 nm. The authors show that thin lipid layer sensitivity can indeed be reached under physiological conditions and that membrane colloid interaction as well as eventual lateral segregation of lipid components may be probed in the future by this technique.
A comparative investigation of methods for protein immobilization on self-assembled monolayers using glutaraldehyde, carbodiimide, and anhydride reagents
Authors: Ducker Robert E. , Montague Matthew T. , Leggett Graham J.
Published: January 2009

Three different approaches to the immobilization of proteins at surfaces have been compared. All rely on the creation of surface groups that bind primary amines on lysine residues. Carboxylic acid terminated self-assembled monolayers (SAMs) have been activated using a water soluble carbodiimide to yield an active ester functionalized surface and with trifluoroacetic anhydride to yield a surface anhydride, and amine terminated SAMs have been activated using glutaraldehyde. Although the degree of surface derivatization by n-alkylamines was greater using the carbodiimide and anhydride methods under anhydrous conditions, the glutaraldehyde activation of amine terminated SAMs yielded significantly greater attachment of streptavidin than is achieved using either of the other methods. This is attributed to the susceptibility to hydrolysis of the active species formed by activation of the carboxylic acid terminated monolayers. Patterned protein structures may be formed by using both glutaraldehyde activation of amine terminated thiols and carbodiimide activation of carboxylic acid terminated thiols, in conjunction with selective photo-oxidation of oligo(ethylene glycol) terminated SAMs.
Editorial for Biointerphases in focus: Surface plasmon resonance-plasmonics
Authors: Liedberg Bo
Published: January 2009

Optical characterization of ultrathin films and interfaces using surface plasmon polariton or surface plasmon resonance (SPR) excitation in “free-electron-like” metals of gold and silver was pioneered by two research groups from Germany in the late 1960s.1,2 They showed that the SPR phenomenon could be excited optically by the method of attenuated total reflection (ATR) either via a very thin air gap-“the Otto configuration”-or by a route where the thin metal film was deposited directly on the base of a glass prism-“the Kretschmann configuration.” Both methods were extensively used to study fundamental optical properties of thin metal films and inorganic/organic coatings deposited on top of the metal film surface. In the following years the SPR-ATR approach became very popular for studies of monomolecular assemblies of Langmuir-Blodgett films on metals3 and later for the determination of molecular orientation4 in such assemblies as well as for measurement of refractive index changes occurring during phase transitions in liquid crystals.5
First and second ionization energies of 1,3,5-trimethylbenzene and 2,4,6-trimethylpyridine
Authors: Milko Petr , Schröder Detlef , Lemr Karel , Žabka Ján , Alcaraz Christian , Roithová Jana
Published: January 2009

The first and second ionization energies of trimethyl substituted analogs of benzene and pyridine are determined by means of mass spectrometry in conjunction with synchrotron radiation. The first ionization energy of 1,3,5-trimethylbenzene amounts to (8.38 ± 0.05) eV and the second ionization energy to (22.8 ± 0.1) eV. The first ionization energy of 2,4,6-trimethylpyridine is determined as (8.65 ± 0.05) eV and the second ionization energy as (23.0 ± 0.1) eV. The ionization energies are compared with those of unsubstituted benzene and pyridine and the effects of the methyl groups are evaluated by means of isodesmic reactions. As expected, it is found that the electron-donating effect of the methyl groups stabilizes neutral pyridine and doubly charged pyridine more than neutral benzene and doubly charged benzene, respectively. Surprisingly, the opposite effect is found for the radical cations, which is ascribed to the unfavorable degenerate electronic structure of benzene radical-cation, which disappears upon the methyl substitution.
Effect of task familiarisation on distribution of energy during a 2000 m cycling time trial
Authors: Corbett J , Barwood M J , Parkhouse K
Published: January 2009

Aim:

To investigate the effect of task familiarisation on the spontaneous pattern of energy expenditure during a series of 2000 m cycling time trials (TTs).

Method:

Nine trained males completed three 2000 m TTs on a Velotron cycling ergometer. To examine pacing strategy, the data were assigned to 250 m “bins,” with the pattern of aerobic and anaerobic energy expenditure calculated from total work accomplished and gas-exchange data.

Results:

There were no significant differences between trials in performance times (191.4 (SD 4.3), 189.4 (4.6), 190.1 (5.6) s), total aerobic (58.3 (2.7), 58.4 (3.1), 58.0 (3.4) kJ) and total anaerobic energy expenditure (16.4 (3.3), 17.3 (2.8), 16.5 (3.1) kJ). Pacing strategy in the second and third TT differed from the first TT in that a lower power output was adopted during the first 500 m, enabling a higher power output during the final 750 m of the TT. This adjustment in the pattern of energy expenditure was mediated by an alteration in the pattern of anaerobic energy expenditure, which paralleled changes in total energy expenditure. Furthermore, participants retained an anaerobic energy “reserve” enabling an end-spurt during the second and third trials.

Conclusion:

Small modifications to the pacing strategy are made following a single bout of exercise, primarily by altering the rate of anaerobic energy expenditure. This may have served to prevent critical metabolic disturbances. The alteration in pacing strategy following the first exercise bout is compatible with a complex intelligent regulatory system.
Multiple work-related accidents: tracing the role of hearing status and noise exposure
Authors: Girard S A , Picard M , Davis A C , Simard M , Larocque R , Leroux T , Turcotte F
Published: January 2009

Objectives:

Our main purpose was to investigate any relationship between noise exposure levels in the workplace, degree of hearing loss (HL), and the relative risk of accident (OR of single or multiple events).

Methods:

We conducted a retrospective study of 52 982 male workers aged 16–64 years with long-standing exposures to occupational noise over a 5-year period, using “hearing status” and “noise exposure” from the registry held by the Quebec National Institute of Public Health. Information on work-related accidents was obtained from the Quebec Workers’ Compensation Board. Hearing threshold level measurements and noise exposures were regressed on the numbers of accidents after adjusting for age.

Results:

Exposure to extremely noisy environments (Leq8h(equivalent noise level for 8 h exposure) ⩾90 dBA) is associated with a higher relative risk of accident. The severity of hearing impairment (average bilateral hearing threshold levels at 3, 4 and 6 kHz) increases the relative risk of single and multiple events when threshold levels exceed 15 dB of hearing loss. The relative risk of multiple events (four or more) is approximately three times higher among severely hearing-impaired workers who are exposed to Leq8h⩾90 dBA.

Conclusion:

Single and multiple events are associated with high noise exposure and hearing status. This suggests that reducing noise exposure contributes to increased safety in noisy industries and prevents hearing loss. Hearing-impaired workers assigned to noisy workstations should be provided with assistive listening devices and efficient communication strategies should be implemented.
Role of the liver in glucose homeostasis in PI 3-kinase p85α-deficient mice
Authors: Aoki Kazutaka , Matsui Junji , Kubota Naoto , Nakajima Hiromu , Iwamoto Keiji , Takamoto Iseki , Tsuji Youki , Ohno Akira , Mori Shuuichi , Tokuyama Kumpei , Murakami Koji , Asano Tomoichiro , Aizawa Shinichi , Tobe Kazuyuki , Kadowaki Takashi , Terauchi Yasuo
Published: January 2009

Phosphoinositide 3-kinase (PI3K) p85α-deficient mice exhibit hypoglycemia as a result of increased insulin sensitivity and glucose uptake in peripheral tissues. Although PI3K is central to the metabolic actions of insulin, its mechanism of action in liver is not well understood. In the present study, we investigated hepatic insulin signaling and glucose homeostasis in p85α-deficient and wild-type mice. In the livers of p85α-deficient mice, p50α played a compensatory role in insulin-stimulated PI3K activation by binding to insulin receptor substrate (IRS)-1/2. In p85α-deficient mice, the ratio of p50α over p110 catalytic subunit of PI3K in the liver was higher than in the muscles. PI3K activity associated with IRS-1/2 was not affected by the lack of p85α in the liver. Insulin-stimulated Akt and phosphatase and tensin homologue deleted on chromosome 10 (PTEN) activities in the liver were similar in p85α-deficient and wild-type mice. A hyperinsulinemic-euglycemic clamp study revealed that the glucose infusion rate and the rate of disappearance were higher in p85α-deficient mice than in wild-type mice but that endogenous glucose production tended to be higher in p85α-deficient mice than in wild-type mice. Consistent with this finding, the expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase in livers after fasting was higher in p85α-deficient mice than in wild-type mice. After mice were fasted, the intrahepatic glucose-6-phosphate level was almost completely depleted in p85α-deficient mice. The glycogen content fell to nearly zero as a result of glycogenolysis shortly after the initiation of fasting in p85α-deficient mice. The absence of an increase in insulin-stimulated PI3K activation in the liver of p85α-deficient mice, unlike the muscles, may be associated with the molecular balance between the regulatory subunit and the catalytic subunit of PI3K. Gluconeogenesis was rather elevated in p85α-deficient mice, compared with in wild-type mice, and the liver seemed to partially compensate for the increase in glucose uptake in peripheral tissues.
Estrogen receptor-α and -β and aromatase knockout effects on lower limb muscle mass and contractile function in female mice
Authors: Brown Marybeth , Ning Jie , Ferreira J. Andries , Bogener Jennifer L. , Lubahn Dennis B.
Published: January 2009

Estrogen (E2) is reported to regulate skeletal muscle mass and contractile function; whether E2exerts its effects through estrogen receptor-α (ERα) or -β (ERβ) is unclear. We determined the effect of ERα or ERβ elimination on muscle mass and contractile function in multiple muscles of the lower limb, muscles with different locomotor tasks and proportions of fiber types I and II: soleus (Sol), plantaris (Plan), tibialis anterior (TA), and gastrocnemius (Gast) in mature female mice. To determine E2elimination effects on muscle, we also used aromatase (Ar) knockout (KO) and wild-type (WT) mice. ERα and ArKO body weights were ∼10 and 20% higher than WT. Although muscle mass tended to show a commensurate increase in both groups, only the TA was significantly larger in ERα ( P < 0.05). Ratios of muscle mass to body mass revealed significantly lower values for Gast and TA in ArKO mice ( P < 0.05). Tetanic tension (Po) per calculated anatomical cross-sectional area (aCSA) in ERα KO was lower in TA and Gast than in WT. Lower Po/aCSA in ERα KO Gast and TA was also supported histologically by significantly less Po/fiber areas ( P < 0.05). ArKO mice also had lower Po/aCSA in Gast and TA compared with WT. ERβ KO and WT mice were comparable in all measures. Our results support the hypothesis that E2effects on skeletal muscle are mediated in part via the ERα but that E2effects may be mediated via more than one mechanism or receptor.
Involvement of the vitamin D receptor in energy metabolism: regulation of uncoupling proteins
Authors: Wong Kari E. , Szeto Frances L. , Zhang Wenshuo , Ye Honggang , Kong Juan , Zhang Zhongyi , Sun Xiao Jian , Li Yan Chun
Published: January 2009

Recent studies have established that vitamin D plays multiple biological roles beyond calcium metabolism; however, whether vitamin D is involved in energy metabolism is unknown. To address this question, we characterized the metabolic phenotypes of vitamin D receptor (VDR)-null mutant mice. Under a normocalcemic condition, VDR-null mice displayed less body fat mass and lower plasma triglyceride and cholesterol levels compared with wild-type (WT) mice; when placed on a high-fat diet, VDR-null mice showed a slower growth rate and accumulated less fat mass globally than WT mice, even though their food intake and intestinal lipid transport capacity were the same as WT mice. Consistent with the lower adipose mass, plasma leptin levels were lower and white adipocytes were histologically smaller in VDR-null mice than WT mice. The rate of fatty acid β-oxidation in the white adipose tissue was higher, and the expression of uncoupling protein (UCP) 1, UCP2 and UCP3 was markedly upregulated in VDR-null mice, suggesting a higher energy expenditure in the mutant mice. Experiments using primary brown fat culture confirmed that 1,25-dihydroxyvitamin D3directly suppressed the expression of the UCPs. Consistently, the energy expenditure, oxygen consumption, and CO2production in VDR-null mice were markedly higher than in WT mice. These data indicate that vitamin D is involved in energy metabolism and adipocyte biology in vivo in part through regulation of β-oxidation and UCP expression.
Endurance swimming stimulates transepithelial calcium transport and alters the expression of genes related to calcium absorption in the intestine of rats
Authors: Teerapornpuntakit Jarinthorn , Dorkkam Nitita , Wongdee Kannikar , Krishnamra Nateetip , Charoenphandhu Narattaphol
Published: January 2009

Endurance impact exercise, e.g., running, is known to enhance the intestinal calcium absorption. However, nonimpact exercise, e.g., swimming, is more appropriate for osteoporotic patients with cardiovascular diseases or disorders of bone and joint, but the effect of swimming on the intestinal calcium transport was unknown. This study, therefore, aimed to investigate the transepithelial calcium transport and the expression of related genes in the intestine of rats trained to swim nonstop 1 h/day, 5 days/wk for 2 wk. We found that endurance swimming stimulated calcium transport in the duodenum, proximal jejunum, and cecum, while decreasing that in the proximal colon. Swimming affected neither the transepithelial potential difference nor resistance. As demonstrated by real-time PCR, the small intestine, especially the duodenum, responded to swimming by upregulating a number of genes related to the transcellular calcium transport, i.e., TRPV5, TRPV6, calbindin-D9k, PMCA1b, and NCX1, and the paracellular calcium transport, i.e., ZO-1, ZO-2, ZO-3, cingulin, occludin, and claudins, as well as nuclear receptor of 1,25(OH)2D3. In contrast, swimming downregulated those genes in the colon. Microarray analysis showed that swimming also altered the expression of duodenal genes related to the transport of several ions and nutrients, e.g., Na+, K+, Cl−, glucose, and amino acids. In conclusion, endurance swimming enhanced intestinal calcium absorption, in part, by upregulating the calcium transporter genes. The present microarray study also provided relevant information for further investigations into the intestinal nutrient and electrolyte transport during nonimpact exercise.
GLUT8, the enigmatic intracellular hexose transporter
Authors: Schmidt Stefan , Joost Hans-Georg , Schürmann Annette
Published: January 2009

GLUT8 is a class III sugar transporter predominantly expressed in testis and brain. In contrast to the class I and class II transporters, hydrophobicity plots predict a short extracellular loop between transmembrane domain (TM)1 and TM2 and a long extracellular loop between TM9 and TM10 that contains the only N-glycosylation site. In vitro translated GLUT8 migrates as a 35-kDa protein that is glycosylated in the presence of microsomal membranes. In heterologous expression systems, glucose transport activity ( Kmof 2 mM) was inhibited by fructose and galactose. The transporter carries an NH2-terminal endosomal/lysosomal targeting motif ([DE]XXXL[LI]). Accordingly, constitutive GLUT8 has been found to be associated with endosomes and lysosomes but also with membranes of the endoplasmic reticulum. A similar distribution was detected after overexpression of wild-type or tagged GLUT8 in different cell systems. In these cells, none of the conventional signals tested induced a translocation of GLUT8 to the plasma membrane. Therefore, GLUT8 appears to catalyze transport of sugars or sugar derivatives through intracellular membranes. Slc2a8 knockout mice were viable, developed normally, and showed mild alterations in brain (increased proliferation of neuronal cells in dentate gyrus of the hippocampus, hyperactivity), heart (impaired transmission of electrical wave through the atrium), and sperm cells (reduced number of motile sperm cells associated with reduced mitochondrial membrane potential and ATP levels in sperm). The links between molecular function, cellular localization and phenotype of the knockout mouse is unclear and remains to be determined.
Dendritic Excitability and Neuronal Morphology as Determinants of Synaptic Efficacy
Authors: Komendantov Alexander O. , Ascoli Giorgio A.
Published: January 2009

The ability to trigger neuronal spiking activity is one of the most important functional characteristics of synaptic inputs and can be quantified as a measure of synaptic efficacy (SE). Using model neurons with both highly simplified and real morphological structures (from a single cylindrical dendrite to a hippocampal granule cell, CA1 pyramidal cell, spinal motoneuron, and retinal ganglion neurons) we found that SE of excitatory inputs decreases with the distance from the soma and active nonlinear properties of the dendrites can counterbalance this global effect of attenuation. This phenomenon is frequency dependent, with a more prominent gain in SE observed at lower levels of background input–output neuronal activity. In contrast, there are no significant differences in SE between passive and active dendrites under higher frequencies of background activity. The influence of the nonuniform distribution of active properties on SE is also more prominent at lower background frequencies. In models with real morphologies, the effect of active dendritic conductances becomes more dramatic and inverts the SE relationship between distal and proximal locations. In active dendrites, distal synapses have higher efficacy than that of proximal ones because of arising dendritic spiking in thin branches with high-input resistance. Lower levels of dendritic excitability can make SE independent of the distance from the soma. Although increasing dendritic excitability may boost SE of distal synapses in real neurons, it may actually reduce overall SE. The results are robust with respect to morphological variation and biophysical properties of the model neurons. The model of CA1 pyramidal cell with realistic distributions of dendritic conductances demonstrated important roles of hyperpolarization-activated (h-) current and A-type K+ current in controlling the efficacy of single synaptic inputs and overall SE differently in basal and apical dendrites.
Cortically Activated Interneurons Shape Spatial Aspects of Cortico-Accumbens Processing
Authors: Gruber Aaron J. , Powell Elizabeth M. , O'Donnell Patricio
Published: January 2009

Basal ganglia circuits are organized as parallel loops that have been proposed to compete in a winner-take-all fashion to determine the appropriate behavioral outcome. However, limited experimental support for strong lateral inhibition mechanisms within striatal regions questions this model. Here, stimulation of the prefrontal cortex (PFC) using naturally occurring bursty patterns inhibited firing in most nucleus accumbens (NA) projection neurons. When an excitatory response was observed for one stimulation site, neighboring PFC sites evoked inhibition in the same neuron. Furthermore, PFC stimulation activated interneurons, and PFC-evoked inhibition was blocked by GABAA antagonists in corticoaccumbens slice preparations. Thus bursting PFC activity recruits local inhibition in the NA, shaping responses of projection neurons with a topographical arrangement that allows inhibition among parallel corticoaccumbens channels. The data indicate a high order of information processing within striatal circuits that should be considered in models of basal ganglia function and disease.
Time Course of Attentional Modulation in the Frontal Eye Field During Curve Tracing
Authors: Khayat P. S. , Pooresmaeili A. , Roelfsema P. R.
Published: January 2009

Neurons in the frontal eye fields (FEFs) register incoming visual information and select visual stimuli that are relevant for behavior. Here we investigated the timing of the visual response and the timing of selection by recording from single FEF neurons in a curve-tracing task that requires shifts of attention followed by an oculomotor response. We found that the behavioral selection signal in area FEF had a latency of 147 ms and that it was delayed substantially relative to the visual response, which occurred 50 ms after stimulus presentation. We compared the FEF responses to activity previously recorded in the primary visual cortex (area V1) during the same task. Visual responses in area V1 preceded the FEF responses, but the latencies of selection signals in areas V1 and FEF were similar. The similarity of timing of selection signals in structures at opposite ends of the visual cortical processing hierarchy supports the view that stimulus selection occurs in an interaction between widely separated cortical regions.
Rat Urinary Bladder Carcinogenesis by Dual‐Acting PPARα + γ Agonists
Authors: Oleksiewicz Martin B. , Southgate Jennifer , Iversen Lars , Egerod Frederikke L.
Published: January 2009

Despite clinical promise, dual‐acting activators of PPARα and γ (here termed PPARα+γ agonists) have experienced high attrition rates in preclinical and early clinical development, due to toxicity. In some cases, discontinuation was due to carcinogenic effect in the rat urothelium, the epithelial layer lining the urinary bladder, ureters, and kidney pelvis. Chronic pharmacological activation of PPARα is invariably associated with cancer in rats and mice. Chronic pharmacological activation of PPARγ can in some cases also cause cancer in rats and mice. Urothelial cells coexpress PPARα as well as PPARγ, making it plausible that the urothelial carcinogenicity of PPARα+γ agonists may be caused by receptor‐mediated effects (exaggerated pharmacology). Based on previously published mode of action data for the PPARα+γ agonist ragaglitazar, and the available literature about the role of PPARα and γ in rodent carcinogenesis, we propose a mode of action hypothesis for the carcinogenic effect of PPARα+γ agonists in the rat urothelium, which combines receptor‐mediated and off‐target cytotoxic effects. The proposed mode of action hypothesis is being explored in our laboratories, towards understanding the human relevance of the rat cancer findings, and developing rapid in vitro or short‐term in vivo screening approaches to faciliate development of new dual‐acting PPAR agonist compounds.
EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite
Authors: Reddy S. Lakshmi , Frost R. L. , Sowjanya G. , Reddy N. C. G. , Reddy G. Siva , Reddy B. J.
Published: January 2009

Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III) ions in the mineral. From EPR studies, the parameters ofgfor Fe(III) andg,A, andDfor Mn(II) are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III) is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.
Genetic and Epigenetic Tumor Suppressor Gene Silencing Are Distinct Molecular Phenotypes Driven by Growth Promoting Mutations in Nonsmall Cell Lung Cancer
Authors: Marsit Carmen J. , Houseman E. Andres , Nelson Heather H. , Kelsey Karl T.
Published: January 2009

Both genetic and epigenetic alterations characterize human nonsmall cell lung cancer (NSCLC), but the biological processes that create or select these alterations remain incompletely investigated. Our hypothesis posits that a roughly reciprocal relationship between the propensity for promoter hypermethylation and a propensity for genetic deletion leads to distinct molecular phenotypes of lung cancer. To test this hypothesis, we examined promoter hypermethylation of 17 tumor suppressor genes, as a marker of epigenetic alteration propensity, and deletion events at the 3p21 region, as a marker of genetic alteration. To model the complex biology between these somatic alterations, we utilized an item response theory model. We demonstrated that tumors exhibiting LOH at greater than 30% of informative alleles in the 3p21 region have a significantly reduced propensity for hypermethylation. At the same time, tumors with activatingKRASmutations showed a significantly increased propensity for hypermethylation of the loci examined, a result similar to what has been observed in colon cancer. These data suggest that NSCLCs have distinct epigenetic or genetic alteration phenotypes acting upon tumor suppressor genes and that mutation of oncogenic growth promoting genes, such asKRAS, is associated with the epigenetic phenotype.
Statistical Time-Frequency Multiplexing of HD Video Traffic in DVB-T2
Authors: Rezaei Mehdi , Bouazizi Imed , Gabbouj Moncef
Published: January 2009

Digital video broadcast-terrestrial 2 (DVB-T2) is the successor of DVB-T standard that allows a two-dimensional multiplexing of broadcast services in time and frequency domains. It introduces an optional time-frequency slicing (TFS) transmission scheme to increase the flexibility of service multiplexing. Utilizing statistical multiplexing (StatMux) in conjunction with TFS is expected to provide a high performance for the broadcast system in terms of resource utilization and quality of service. In this paper, a model for high-definition video (HDV) traffic is proposed. Then, utilizing the proposed model, the performance of StatMux of HDV broadcast services over DVB-T2 is evaluated. Results of the study show that implementation of StatMux in conjunction with the newly available features in DVB-T2 provides a high performance for the broadcast system.
Clinico-Haematological Profile of Acute Megakaryoblastic Leukaemia: Report of Five Cases
Authors: Sharma Sunita , Nangia Anita , Jain Malhotra Sonal , Narayan Shashi , Harbhajanka Aparna , Singh Sarika
Published: January 2009

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia. Although known as a distinct entity for a very long time, because of lack of distinct clinical features and morphological criteria, it is difficult to diagnose this variant correctly. We herein present the clinical, morphological, cytochemical, and immunocytochemical features of five cases of AMKL. Certain morphological features such as presence of abnormal platelet count, giant platelets, and cytoplasmic blebbing in blasts were found to be important pointers towards the diagnosis. However, none of the features were found to be consistent and thus morphological diagnosis has to be confirmed by cytochemistry and immunocytochemistry.
Prediction of Clinical Outcome in Multiple Lung Cancer Cohorts by Integrative Genomics: Implications for Chemotherapy Selection
Authors: Broët Philippe , Camilleri-Broët Sophie , Zhang Shenli , Alifano Marco , Bangarusamy Dhinoth , Battistella Maxime , Wu Yonghui , Tuefferd Marianne , Régnard Jean-François , Lim Elaine , Tan Patrick , Miller Lance D.
Published: January 2009

The role of adjuvant chemotherapy in patients with stage IB non–small-cell lung cancer (NSCLC) is controversial. Identifying patient subgroups with the greatest risk of relapse and, consequently, most likely to benefit from adjuvant treatment thus remains an important clinical challenge. Here, we hypothesized that recurrent patterns of genomic amplifications and deletions in lung tumors could be integrated with gene expression information to establish a robust predictor of clinical outcome in stage IB NSCLC. Using high-resolution microarrays, we generated tandem DNA copy number and gene expression profiles for 85 stage IB lung adenocarcinomas/large cell carcinomas. We identified specific copy number alterations linked to relapse-free survival and selected genes within these regions exhibiting copy number–driven expression to construct a novel integrated signature (IS) capable of predicting clinical outcome in this series (P = 0.02). Importantly, the IS also significantly predicted clinical outcome in two other independent stage I NSCLC cohorts (P = 0.003 and P = 0.025), showing its robustness. In contrast, a more conventional molecular predictor based solely on gene expression, while capable of predicting outcome in the initial series, failed to significantly predict outcome in the two independent data sets. Our results suggest that recurrent copy number alterations, when combined with gene expression information, can be successfully used to create robust predictors of clinical outcome in early-stage NSCLC. The utility of the IS in identifying early-stage NSCLC patients as candidates for adjuvant treatment should be further evaluated in a clinical trial. [Cancer Res 2009;69(3):1055–62]
Vasculostatin Inhibits Intracranial Glioma Growth and Negatively RegulatesIn vivoAngiogenesis through a CD36-Dependent Mechanism
Authors: Kaur Balveen , Cork Sarah M. , Sandberg Eric M. , Devi Narra S. , Zhang Zhaobin , Klenotic Philip A. , Febbraio Maria , Shim Hyunsuk , Mao Hui , Tucker-Burden Carol , Silverstein Roy L. , Brat Daniel J. , Olson Jeffrey J. , Van Meir Erwin G.
Published: January 2009

Angiogenesis is a critical physiologic process that is appropriated during tumorigenesis. Little is known about how this process is specifically regulated in the brain. Brain angiogenesis inhibitor-1 (BAI1) is a brain-predominant seven-transmembrane protein that contains five antiangiogenic thrombospondin type-1 repeats (TSR). We recently showed that BAI1 is cleaved at a conserved proteolytic cleavage site releasing a soluble, 120 kDa antiangiogenic factor called vasculostatin (Vstat120). Vstat120 has been shown to inhibit in vitro angiogenesis and suppress subcutaneous tumor growth. Here, we examine its effect on the intracranial growth of malignant gliomas and further study its antitumor mechanism. First, we show that expression of Vstat120 strongly suppresses the intracranial growth of malignant gliomas, even in the presence of the strong proangiogenic stimulus mediated by the oncoprotein epidermal growth factor receptor variant III (EGFRvIII). This tumor-suppressive effect is accompanied by a decrease in tumor vascular density, suggesting a potent antiangiogenic effect in the brain. Second, and consistent with this interpretation, we find that treatment with Vstat120 reduces the migration of cultured microvascular endothelial cells in vitro and inhibits corneal angiogenesis in vivo. Third, we show that these antivascular effects critically depend on the presence of the cell surface receptor CD36 on endothelial cells in vitro and in vivo, supporting the role of Vstat120 TSRs in mediating these effects. These results advance the understanding of brain-specific angiogenic regulation, and suggest that Vstat120 has therapeutic potential in the treatment of brain tumors and other intracerebral vasculopathies. [Cancer Res 2009;69(3):1212–20]
A Gonadotropin-Releasing Hormone-II Antagonist Induces Autophagy of Prostate Cancer Cells
Authors: Kim Dong-Ki , Yang Ji Sook , Maiti Kaushik , Hwang Jong-Ik , Kim Kyungjin , Seen Dongseung , Ahn Younghee , Lee Cheolju , Kang Byeong-Cheol , Kwon Hyuk Bang , Cheon Jun , Seong Jae Young
Published: January 2009

Gonadotropin-releasing hormone-I (GnRH-I) is known to directly regulate prostate cancer cell proliferation. However, the role of GnRH-II in prostate cancer is unclear. Here, we investigated the effect of the GnRH-II antagonist trptorelix-1 (Trp-1) on growth of PC3 prostate cancer cells. Trp-1 induced growth inhibition of PC3 cells in vitro and inhibited growth of PC3 cells xenografted into nude mice. FITC-N3, an FITC-conjugated Trp-1 analogue, was largely present in the mitochondria of prostate cancer cells, but not in other cells that are not derived from the prostate. Trp-1–induced PC3 growth inhibition was associated with decreased mitochondrial membrane potential and increased levels of mitochondrial and cytosolic reactive oxygen species (ROS). Growth inhibition was partially prevented by cotreating cells with N-acetyl cysteine, an antioxidant. Cytochrome c release and caspase-3 activation were not detected in Trp-1–treated cells. However, Trp-1 induced autophagosome formation, as seen by increased LysoTracker staining and recruitment of microtubule-associated protein 1 light chain 3 to these new lysosomal compartments. Trp-1–induced autophagy was accompanied by decreased AKT phosphorylation and increased c-Jun NH2 terminal kinase phosphorylation, two events known to be linked to autophagy. Taken together, these data suggest that Trp-1 directly induces mitochondrial dysfunction and ROS increase, leading to autophagy of prostate cancer cells. GnRH-II antagonists may hold promise in the treatment of prostate cancer. [Cancer Res 2009;69(3):923–31]
Distinct Roles of BARD1 Isoforms in Mitosis: Full-Length BARD1 Mediates Aurora B Degradation, Cancer-Associated BARD1β Scaffolds Aurora B and BRCA2
Authors: Ryser Stephan , Dizin Eva , Jefford Charles Edward , Delaval Bénédicte , Gagos Sarantis , Christodoulidou Agni , Krause Karl-Heinz , Birnbaum Daniel , Irminger-Finger Irmgard
Published: January 2009

The BRCA1-associated ring domain protein 1 (BARD1) interacts with BRCA1 via its RING finger domain. The BARD1-BRCA1 complex participates in DNA repair, cell cycle control, genomic stability, and mitotic spindle formation through its E3 ubiquitin ligase activity. Cancer cells express several BARD1 protein isoforms, including the RING finger–deficient variant BARD1β. Here, we show that BARD1 has BRCA1-dependent and BRCA1-independent functions in mitosis. BARD1, but not BRCA1, localizes to the midbody at telophase and cytokinesis, where it colocalizes with Aurora B. The 97-kDa full-length (FL) BARD1 coimmunoprecipates with BRCA1, but the 82-kDa BARD1β coimmunoprecipitates with Aurora B and BRCA2. We used selective small interfering RNAs to distinguish the functions of FL BARD1 and BARD1β. Depletion of FL BARD1 had only minor effects on cell growth and did not abolish midbody localization of BARD1 staining, but resulted in massive up-regulation of Aurora B. In contrast, suppression of FL BARD1 and BARD1β led to growth arrest and correlated with various mitotic defects and disappearance of midbody localization of BARD1 staining. Our data suggest a novel function of FL BARD1 in Aurora B ubiquitination and degradation, opposing a proproliferative function of BARD1β in scaffolding Aurora B and BRCA2. Thus, loss of FL BARD1 and up-regulation of Aurora B, as observed in cancer cells, can be explained by an imbalance of FL BARD1 and BARD1β. [Cancer Res 2009;69(3):1125–34]
A Destructive Cascade Mediated by CCL2 Facilitates Prostate Cancer Growth in Bone
Authors: Li Xin , Loberg Robert , Liao Jinhui , Ying Chi , Snyder Linda A. , Pienta Kenneth J. , McCauley Laurie K.
Published: January 2009

Monocyte chemoattractant protein 1 (CCL2) is a recently identified prominent regulator of prostate cancer growth and metastasis. The purpose of this study was to investigate the mechanistic role of CCL2 in prostate cancer growth in bone. The present study found that CCL2 was up-regulated in osteoblasts (3-fold by PC-3 and 2-fold by VCaP conditioned medium) and endothelial cells (2-fold by PC-3 and VCaP conditioned medium). Parathyroid hormone-related protein (PTHrP) treatment of osteoblastic cells up-regulated CCL2 and was blocked by a PTHrP antagonist, suggesting that prostate cancer–derived PTHrP plays an important role in elevation of osteoblast-derived CCL2. CCL2 indirectly increased blood vessel formation in endothelial cells through vascular endothelial growth factor-A, which was up-regulated 2-fold with administration of CCL2 in prostate cancer cells. In vivo, anti-CCL2 treatment suppressed tumor growth in bone. The decreased tumor burden was associated with decreased bone resorption (serum TRAP5b levels were decreased by 50–60% in anti–CCL2-treated animals from VCaP or PC-3 cell osseous lesions) and microvessel density was decreased by 70% in anti–CCL2-treated animals with bone lesions from VCaP cells. These data suggest that a destructive cascade is driven by tumor cell–derived, PTHrP-mediated induction of CCL2, which facilitates tumor growth via enhanced osteoclastic and endothelial cell activity in bone marrow. Taken together, CCL2 mediates the interaction between tumor-derived factors and host-derived chemokines acting in cooperation to promote skeletal metastasis. [Cancer Res 2009;69(4):1685–92]
Histone Deacetylases Are Required for Androgen Receptor Function in Hormone-Sensitive and Castrate-Resistant Prostate Cancer
Authors: Welsbie Derek S. , Xu Jin , Chen Yu , Borsu Laetitia , Scher Howard I. , Rosen Neal , Sawyers Charles L.
Published: January 2009

Transcriptional activity of the androgen receptor (AR) is crucial for growth and survival of prostate cancer even upon development of resistance to androgen ablation and antiandrogen therapies. Therefore, novel therapies that can suppress AR transcriptional activity when conventional hormone therapies fail are needed. Here, we show that histone deacetylase (HDAC) inhibitors, including SAHA (vorinostat) and LBH589, which are currently being tested in clinic, could be such a therapy. HDAC inhibitors block the AR-mediated transcriptional activation of many genes, including the TMPRSS2 gene involved in fusion with ETS family members in a majority of prostate cancers. Genetic knockdown of either HDAC1 or HDAC3 can also suppress expression of AR-regulated genes, recapitulating the effect of HDAC inhibitor treatment. Whereas HDAC inhibitor treatment can lower androgen receptor protein levels in prostate cancer cells, we show that independent of AR protein levels, HDAC inhibitors block AR activity through inhibiting the assembly of coactivator/RNA polymerase II complex after AR binds to the enhancers of target genes. Failed complex assembly is associated with a phase shift in the cyclical wave of AR recruitment that typically occurs in response to ligand treatment. HDAC inhibitors retain the ability to block AR activity in castration-resistant prostate cancer models and, therefore, merit clinical investigation in this setting. The HDAC-regulated AR target genes defined here can serve as biomarkers to ensure sufficient levels of HDAC inhibition. [Cancer Res 2009;69(3):958–66]