bluuebunny/crossref_metadata_2025 huggingface dataset:
Sand sampling below the water table using the 200 mm diameter Laval sampler
Authors: Konrad J.-M. , St-Laurent S. , Gilbert F. , Leroueil S.
Published: August 2008

The large-diameter Laval sampler, originally developed for sampling soft sensitive marine clays, was used to obtain samples from saturated cohesionless soil deposits. This paper describes the different operations for sampling sand deposits, which vary slightly from the conventional procedures used in clays. To preserve the fragile soil structure, the samples are frozen unidirectionally in open system conditions once at the ground surface. Field trial tests, conducted at two sites in the province of Quebec, showed that the Laval sampler successfully obtained 46 cm long samples from depths of about 6 m. Water content distribution throughout the samples showed little variation, indicating that disturbance was minimal in these large-diameter samples. Key words : sand, saturated, large sampler, freezing, performance.
Flow slides in the Netherlands: experience and engineering practice
Authors: Silvis F. , Groot M.B. de
Published: August 2008

This paper deals with flow slide experience in the Netherlands. It gives an extensive survey of empirical field data concerning the geological characteristics of the region, the profiles just before the flow slides, and the damage that flow slides can cause. The traditional Dutch procedure for analyzing the flow slide potential of underwater sand slopes is described. This is an engineering approach that is mainly based on the empirical field data, together with geological surveys and soil investigations performed at the relevant site. Key words : sand, collapse, flow slides, liquefaction, slope stability.
EFFECT OF MEDITATION ON SCALING BEHAVIOR AND COMPLEXITY OF HUMAN HEART RATE VARIABILITY
Authors: SARKAR A. , BARAT P.
Published: August 2008

The heart beat data recorded from samples before and during meditation are analyzed using two different scaling analysis methods. These analyses revealed that meditation severely affects the long range correlation of heart beat of a normal heart. Moreover, it is found that meditation induces periodic behavior in the heart beat. The complexity of the heart rate variability is quantified using multiscale entropy analysis and recurrence analysis. The heart beat during meditation is found to be more complex.
PORTFOLIO SELECTION AND ONLINE LEARNING
Authors: LEVINA TATSIANA , SHAFER GLENN
Published: August 2008

This paper studies a new strategy for selecting portfolios in the stock market. The strategy is inspired by two streams of previous work: (1) work on universalization of strategies for portfolio selection, which began with Thomas Cover's work on constant rebalanced portfolios, published in 1991,4 and (2) more general work on universalization of online algorithms,17,21,23,30 especially Vladimir Vovk's work on the aggregating algorithm and Markov switching strategies.32 The proposed investment strategy achieves asymptotically the same exponential rate of growth as the portfolio that turns out to be best expost in the long run and does not require any underlying statistical assumptions on the nature of the stock market.
MANY-VALUED R-S MEMORY CIRCUITS
Authors: PETRÍK MILAN
Published: August 2008

In this paper we present a many-valued memory circuit based on a generalization of the R-S memory circuit known from the two-valued logical circuits.

Based on this many-valued R-S memory circuit we introduce a many-valued level-controlled memory circuit and a many-valued edge-controlled memory circuit of type “master-slave”.

We discuss problems of the stability of the circuit with respect to small errors of input and output signals as well as to small errors of the gates. We show that the stability can be preserved by restricting the set of logical values, i.e. the interval [0, 1], to a finite discrete subset of this interval.

We find the set of many-valued operations which are suitable for the implementation of the many-valued R-S memory circuit.
ON ENTROPY OF FUZZY SETS
Authors: HWANG CHAO-MING , YANG MIIN-SHEN
Published: August 2008

In this paper we deal with the entropy of fuzzy sets. We first review several defined entropies of fuzzy sets and then propose a new one. Some comparisons are made with some existing entropies to show the effectiveness of the proposed one.
AN OVERVIEW OF DISTANCE AND SIMILARITY MEASURES OF INTUITIONISTIC FUZZY SETS
Authors: XU Z. S. , CHEN J.
Published: August 2008

The Intuitionistic Fuzzy Sets (IFSs), originated by Atanassov [1], is a useful tool to deal with vagueness and ambiguity. In the short time since their first appearance, many different distance and similarity measures of IFSs have been proposed, but they are scattered through the literature. In this paper, we give a comprehensive overview of distance and similarity measures of IFSs. Based on the weighted Hamming distance, the weighted Euclidean distance, and the weighted Hausdorff distance, respectively, we define some continuous distance and similarity measures for IFSs. We also utilize geometric distance model to define some continuous distance and similarity measures for IFSs, which are the various combinations and generalizations of the weighted Hamming distance, the weighted Euclidean distance and the weighted Hausdorff distance. Then we extend these distance and similarity measures for Interval-Valued Intuitionistic Fuzzy Sets (IVIFSs).
Connexin26 deafness associated mutations show altered permeability to large cationic molecules
Authors: Meşe Gülistan , Valiunas Virginijus , Brink Peter R. , White Thomas W.
Published: August 2008

Intercellular communication is important for cochlear homeostasis because connexin26 (Cx26) mutations are the leading cause of hereditary deafness. Gap junctions formed by different connexins have unique selectivity to large molecules, so compensating for the loss of one isoform can be challenging in the case of disease causing mutations. We compared the properties of Cx26 mutants T8M and N206S with wild-type channels in transfected cells using dual whole cell voltage clamp and dye flux experiments. Wild-type and mutant channels demonstrated comparable ionic coupling, and their average unitary conductance was ∼106 and ∼60 pS in 120 mM K+-aspartate− and TEA+-aspartate− solution, respectively, documenting their equivalent permeability to K+ and TEA+. Comparison of cAMP, Lucifer Yellow (LY), and ethidium bromide (EtBr) transfer revealed differences in selectivity for larger anionic and cationic tracers. cAMP and LY permeability to wild-type and mutant channels was similar, whereas the transfer of EtBr through mutant channels was greatly reduced compared with wild-type junctions. Altered permeability of Cx26 to large cationic molecules suggests an essential role for biochemical coupling in cochlear homeostasis.
Reduced citrulline availability by OTC deficiency in mice is related to reduced nitric oxide production
Authors: Luiking Yvette C. , Hallemeesch Marcella M. , van de Poll Marcel C. , Dejong Cornelis H. C. , de Jonge Wouter J. , Lamers Wouter H. , Deutz Nicolaas E. P.
Published: August 2008

The amino acid arginine is the sole precursor for nitric oxide (NO) synthesis. We recently demonstrated that an acute reduction of circulating arginine does not compromise basal or LPS-inducible NO production in mice. In the present study, we investigated the importance of citrulline availability in ornithine transcarbamoylase-deficient spfash (OTCD) mice on NO production, using stable isotope techniques and C57BL6/J (wild-type) mice controls. Plasma amino acids and tracer-to-tracee ratios were measured by LC-MS. NO production was measured as the in vivo conversion of l-[guanidino-15N2]arginine to l-[guanidine-15N]citrulline; de novo arginine production was measured as conversion of l-[ureido-13C-5,5-2H2]citrulline to l-[guanidino-13C-5,5-2H2]arginine. Protein metabolism was measured using l-[ ring-2H5]phenylalanine and l-[ ring-2H2]tyrosine. OTC deficiency caused a reduction of systemic citrulline concentration and production to 30–50% ( P < 0.001), reduced de novo arginine production ( P < 0.05), reduced whole-body NO production to 50% ( P < 0.005), and increased net protein breakdown by a factor of 2-4 ( P < 0.001). NO production was twofold higher in female than in male OTCD mice in agreement with the X-linked location of the OTC gene. In response to LPS treatment (10 mg/kg ip), circulating arginine increased in all groups ( P < 0.001), and NO production was no longer affected by the OTC deficiency due to increased net protein breakdown as a source for arginine. Our study shows that reduced citrulline availability is related to reduced basal NO production via reduced de novo arginine production. Under basal conditions this is probably cNOS-mediated NO production. When sufficient arginine is available after LPS stimulated net protein breakdown, NO production is unaffected by OTC deficiency.
Neurogenic-nitric oxide interactions affecting brachial artery mechanics in humans: roles of vessel distensibility vs. diameter
Authors: Salzer Deborah A. , Medeiros Philip J. , Craen Rosemary , Shoemaker J. Kevin
Published: August 2008

The purpose of this investigation was to assess the interactive influence of sympathetic activation and supplemental nitric oxide (NO) on brachial artery distensibility vs. its diameter. It was hypothesized that 1) sympathetic activation and NO competitively impact muscular conduit artery (brachial artery) mechanics, and 2) neurogenic constrictor input affects conduit vessel stiffness independently of outright changes in conduit vessel diastolic diameter. Lower body negative pressure (LBNP) and a cold pressor stress (CPT) were used to study the changes in conduit vessel mechanics when the increased sympathetic outflow occurred with and without changes in heart rate (LBNP −40 vs. −15 mmHg) and blood pressure (CPT vs. LBNP). These maneuvers were performed in the absence and presence of nitroglycerin. Neither LBNP nor CPT altered brachial artery diastolic diameter; however, distensibility was reduced by 25 to 54% in each reflex (all P < 0.05). This impact of sympathetic activation on brachial artery distensibility was not altered by nitroglycerin supplementation (21–54%; P < 0.05), although baseline diameter was increased by the exogenous NO ( P < 0.05). The results indicate that sympathetic excitation can reduce the distensibility of the brachial artery independently of concurrent changes in diastolic diameter, heart rate, and blood pressure. However, exogenous NO did not minimize or reverse brachial stiffening during sympathetic activation. Therefore, sympathetic outflow appears to impact the stiffness of this conduit vessel rather than its diastolic diameter or, by inference, its local resistance to flow.
Nonlinearity and fractality in the variability of cardiac period in the lizard,Gallotia galloti: effects of autonomic blockade
Authors: De Vera Luis , Santana Alejandro , Gonzalez Julian J.
Published: August 2008

Both nonlinear and fractal properties of beat-to-beat R-R interval variability signal (RRV) of freely moving lizards ( Gallotia galloti) were studied in baseline and under autonomic nervous system blockade. Nonlinear techniques allowed us to study the complexity, chaotic behavior, nonlinearity, stationarity, and regularity over time of RRV. Scaling behavior of RRV was studied by means of fractal techniques. The autonomic nervous system blockers used were atropine, propranolol, prazosin, and yohimbine. The nature of RRV was linear in baseline and under β-, α1- and α2-adrenoceptor blockades. Atropine changed the linear nature of RRV to nonlinear and increased its stationarity, regularity and fractality. Propranolol increased the complexity and chaotic behavior, and decreased the stationarity, regularity, and fractality of RRV. Both prazosin and yohimbine did not change any of the nonlinear and fractal properties of RRV. It is suggested that 1) the use of both nonlinear and fractal analysis is an appropriate approach for studying cardiac period variability in reptiles; 2) the cholinergic activity, which seems to make the α1-, α2- and β-adrenergic activity interaction unnecessary, determines the linear behavior in basal RRV; 3) fractality, as well as both RRV regularity and stationarity over time, may result from the balance between cholinergic and β-adrenergic activities opposing actions; 4) β-adrenergic activity may buffer both the complexity and chaotic behavior of RRV, and 5) neither the α1- nor the α2-adrenergic activity seem to be involved in the mediation of either nonlinear or fractal components of RRV.
Electrophysiological and neuroanatomical evidence of sexual dimorphism in aortic baroreceptor and vagal afferents in rat
Authors: Li Bai-Yan , Qiao Guo-Fen , Feng Bin , Zhao Rui-Bo , Lu Yan-Jie , Schild John H.
Published: August 2008

Evidence for sexual dimorphism in autonomic control of cardiovascular function is both compelling and confounding. Across healthy and disease populations sex-associated differences in neurocirculatory hemodynamics are far too complex to be entirely related to sex hormones. As an initial step toward identifying additional physiological mechanisms, we investigated whether there is a sex bias in the relative expression of low-threshold-myelinated and high-threshold-unmyelinated aortic baroreceptor afferents in rats. These two types of afferent fibers have markedly different reflexogenic effects upon heart rate and blood pressure and thus the potential impact upon baroreflex dynamics could be substantial. Our results, using a combination of a patch-clamp study of fluorescently identified aortic baroreceptor neurons (ABN) and morphometric analysis of aortic baroreceptor nerve fibers, demonstrate that females exhibit a greater percentage of myelinated baroreceptor fibers (24.8% vs. 18.7% of total baroreceptor fiber population, P < 0.01) and express a functional subtype of myelinated ABN rarely found in age-matched males (11% vs. 2.3%, n = 107, P < 0.01). Interestingly, this neuronal phenotype is more prevalent in the general population of female vagal afferent neurons (17.7% vs. 3.8%, n = 169, P < 0.01), and ovariectomy does not alter its expression but does lessen neuronal excitability. These data suggest there are fundamental neuroanatomical and electrophysiological differences between aortic baroreceptor afferents of female and male rats. Possible explanations are presented as to how such a greater prevalence of low-threshold myelinated afferents could be a contributing factor to the altered baroreflex sensitivity and vagal tone of females compared with males.
Asymmetric dimethylarginine, oxidative stress, and vascular nitric oxide synthase in essential hypertension
Authors: Wang Dan , Strandgaard Svend , Iversen Jens , Wilcox Christopher S.
Published: August 2008

We reported impaired endothelium-derived relaxation factor/nitric oxide (EDRF/NO) responses and constitutive nitric oxide synthase (cNOS) activity in subcutaneous vessels dissected from patients with essential hypertension ( n = 9) compared with normal controls ( n = 10). We now test the hypothesis that the patients in this study have increased circulating levels of the cNOS inhibitor, asymmetric dimethylarginine (ADMA), or the lipid peroxidation product of linoleic acid, 13-hydroxyoctadecadienoic acid (HODE), which is a marker of reactive oxygen species. Patients had significantly ( P < 0.001) elevated (means ± SD) plasma levels of ADMA (PADMA, 766 ± 217 vs. 393 ± 57 nmol/l) and symmetric dimethylarginine (PSDMA: 644 ± 140 vs. 399 ± 70 nmol/l) but similar levels of l-arginine accompanied by significantly ( P < 0.015) increased rates of renal ADMA excretion (21 ± 9 vs. 14 ± 5 nmol/μmol creatinine) and decreased rates of renal ADMA clearance (18 ± 3 vs. 28 ± 5 ml/min). They had significantly increased plasma levels of HODE (PHODE: 309 ± 30 vs. 226 ± 24 nmol/l) and renal HODE excretion (433 ± 93 vs. 299 ± 67 nmol/μmol creatinine). For the combined group of normal and hypertensive subjects, the individual values for plasma levels of ADMA and HODE were both significantly ( P < 0.001) and inversely correlated with microvascular EDRF/NO and positively correlated with mean blood pressure. In conclusion, elevated levels of ADMA and oxidative stress in a group of hypertensive patients could contribute to the associated microvascular endothelial dysfunction and elevated blood pressure.
TNFR1 signaling resistance associated with female stem cell cytokine production is independent of TNFR2-mediated pathways
Authors: Markel Troy A. , Crisostomo Paul R. , Wang Meijing , Wang Yue , Lahm Tim , Novotny Nathan M. , Tan Jiangning , Meldrum Daniel R.
Published: August 2008

End-organ ischemia is a common source of patient morbidity and mortality. Stem cell therapy represents a novel treatment modality for ischemic diseases and may aid injured tissues through the release of beneficial paracrine mediators. Female bone marrow mesenchymal stem cells (MSCs) have demonstrated a relative resistance to detrimental TNF receptor 1 (TNFR1) signaling and are thought to be superior to male stem cells in limiting inflammation. However, it is not known whether sex differences exist in TNF receptor 2 (TNFR2)-ablated MSCs. Therefore, we hypothesized that 1) sex differences would be observed in wild-type (WT) and TNFR2-ablated MSC cytokine signaling, and 2) the production of IL-6, VEGF, and IGF-1 in males, but not females, would be mediated through TNFR2. MSCs were harvested from male and female WT and TNFR2 knockout (TNFR2KO) mice and were subsequently exposed to TNF (50 ng/ml) or LPS (100 ng/ml). After 24 h, supernatants were collected and measured for cytokines. TNF and LPS stimulated WT stem cells to produce cytokines, but sex differences were only seen in IL-6 and IGF-1 after TNF stimulation. Ablation of TNFR2 increased VEGF and IGF-1 production in males compared with wild-type, but no difference was observed in females. Female MSCs from TNFR2KOs produced significantly lower levels of VEGF and IGF-1 compared with male TNFR2KOs. The absence of TNFR2 signaling appears to play a greater role in male MSC cytokine production. As a result, male, but not female stem cell cytokine production may be mediated through TNFR2 signaling cascades.
Calcium-sensing receptor signaling pathways in medullary thick ascending limb cells mediate COX-2-derived PGE2production: functional significance
Authors: Abdullah Huda Ismail , Pedraza Paulina L. , McGiff John C. , Ferreri Nicholas R.
Published: August 2008

We determined the functional implications of calcium-sensing receptor (CaR)-dependent, Gq- and Gi-coupled signaling cascades, which work in a coordinated manner to regulate activity of nuclear factor of activated T cells and tumor necrosis factor (TNF)-α gene transcription that cause expression of cyclooxygenase (COX)-2-derived prostaglandin E2(PGE2) synthesis by rat medullary thick ascending limb cells (mTAL). Interruption of Gq, Gi, protein kinase C (PKC), or calcineurin (CaN) activities abolished CaR-mediated COX-2 expression and PGE2synthesis. We tested the hypothesis that these pathways contribute to the effects of CaR activation on ion transport in mTAL cells. Ouabain-sensitive O2consumption, an in vitro correlate of ion transport in the mTAL, was inhibited by ∼70% in cells treated for 6 h with extracellular Ca2+(1.2 mM), an effect prevented in mTAL cells transiently transfected with a dominant negative CaR overexpression construct (R796W), indicating that the effect was initiated by stimulation of the CaR. Pretreatment with the COX-2-selective inhibitor, NS-398 (1 μM), reversed CaR-activated decreases in ouabain-sensitive O2consumption by ∼60%, but did not alter basal levels of ouabain-sensitive O2consumption. Similarly, inhibition of either Gq, Gi, PKC, or CaN, which are components of the mechanism associated with CaR-stimulated COX-2-derived PGE2synthesis, reversed the inhibitory effects of CaR on O2consumption without affecting basal O2consumption. Our findings identified signaling elements required for CaR-mediated TNF production that are integral components regulating mTAL function via a mechanism involving COX-2 expression and PGE2production.
Frequency-Specific Coupling in the Cortico-Cerebellar Auditory System
Authors: Pastor M. A. , Vidaurre C. , Fernández-Seara M. A. , Villanueva A. , Friston K. J.
Published: August 2008

Induced oscillatory activity in the auditory cortex peaks at around 40 Hz in humans. Using regional cerebral blood flow and positron emission tomography we previously confirmed frequency-selective cortical responses to 40-Hz tones in auditory primary cortices and concomitant bilateral activation of the cerebellar hemispheres. In this study, using functional magnetic resonance imaging (fMRI) we estimated the influence of 40-Hz auditory stimulation on the coupling between auditory cortex and superior temporal sulcus (STS) and Crus II, using a dynamic causal model of the interactions between medial geniculate nuclei, auditory superior temporal gyrus (STG)/STS, and the cerebellar Crus II auditory region. Specifically, we tested the hypothesis that 40-Hz-selective responses in the cerebellar Crus II auditory region could be explained by frequency-specific enabling of interactions in the auditory cortico–cerebellar–thalamic loop. Our model comparison results suggest that input from auditory STG/STS to cerebellum is enhanced selectively at gamma-band frequencies around 40 Hz.
SK (KCa2) Channels Do Not Control Somatic Excitability in CA1 Pyramidal Neurons But Can Be Activated by Dendritic Excitatory Synapses and Regulate Their Impact
Authors: Gu Ning , Hu Hua , Vervaeke Koen , Storm Johan F.
Published: August 2008

Calcium-activated K+ channels of the KCa2 type (SK channels) are prominently expressed in the mammalian brain, including hippocampus. These channels are thought to underlie neuronal excitability control and have been implicated in plasticity, memory, and neural disease. Contrary to previous reports, we found that somatic spike-evoked medium afterhyperpolarizations (mAHPs) and corresponding excitability control were not caused by SK channels but mainly by Kv7/KCNQ/M channels in CA1 hippocampal pyramidal neurons. Thus apparently, these SK channels are hardly activated by somatic Na+ spikes. To further test this conclusion, we used sharp electrode, whole cell, and perforated-patch recordings from rat CA1 pyramidal neurons. We found that SK channel blockers consistently failed to suppress mAHPs under a range of experimental conditions: mAHPs following single spikes or spike trains, at −60 or −80 mV, at 20–30°C, in low or elevated extracellular [K+], or spike trains triggered by synaptic stimulation after blocking N-methyl-d-aspartic acid receptors (NMDARs). Nevertheless, we found that SK channels in these cells were readily activated by artificially enhanced Ca2+ spikes, and an SK channel opener (1-ethyl-2-benzimidazolinone) enhanced somatic AHPs following Na+ spikes, thus reducing excitability. In contrast to CA1 pyramidal cells, bursting pyramidal cells in the subiculum showed a Na+ spike-evoked mAHP that was reduced by apamin, indicating cell-type-dependent differences in mAHP mechanisms. Testing for other SK channel functions in CA1, we found that field excitatory postsynaptic potentials mediated by NMDARs were enhanced by apamin, supporting the idea that dendritic SK channels are activated by NMDAR-dependent calcium influx. We conclude that SK channels in rat CA1 pyramidal cells can be activated by NMDAR-mediated synaptic input and cause feedback regulation of synaptic efficacy but are normally not appreciably activated by somatic Na+ spikes in this cell type.
Function of Neuromuscular Synapses in the Zebrafish Choline-Acetyltransferase Mutantbajan
Authors: Wang Meng , Wen Hua , Brehm Paul
Published: August 2008

We have identified a zebrafish mutant line, bajan, in which compromised motility and fatigue result from a point mutation in the gene coding choline acetyltransferase (ChAT), the enzyme responsible for acetylcholine (ACh) synthesis. Although the mutation predicts loss of ChAT function, bajan inexplicably retains low levels of neuromuscular transmission. We exploited this residual activity and determined the consequences for synaptic function. The attenuated synaptic responses were a direct consequence of a decrease in both resting mean quantal size and quantal content. To replicate behavioral fatigue in swimming, motorneurons were stimulated at high frequencies. A prominent reduction in quantal content, reflecting vesicle depletion, was coincident with a small additional reduction in quantal size. In humans, defective ChAT leads to episodic apnea, a form of congenital myasthenic syndrome characterized by use-dependent fatigue. In contrast to bajan, however, afflicted individuals exhibit a normal resting quantal size and quantal content. The fatigue in humans results from a pronounced long-lasting drop in quantal size with little or no change in quantal content. These differences have important implications for interpreting fatigue as well as on understanding the impact of ACh availability on vesicle filling and recycling.
Kv1 Potassium Channel Complexes In Vivo Require Kvβ2 Subunits in Dorsal Spinal Neurons
Authors: Pineda Ricardo H. , Knoeckel Christopher S. , Taylor Alison D. , Estrada-Bernal Adriana , Ribera Angeles B.
Published: August 2008

Whereas Kvβ2 subunits modulate potassium current properties carried by Kv1 channel complexes in heterologous systems, little is known about the contributions of Kvβ2 subunits to native potassium channel function. Using antisense approaches and in situ recordings from Xenopus embryo spinal cord neurons, we tested the in vivo roles of Kvβ2 subunits in modulation of voltage-dependent potassium current ( IKv). We focused on 1) two different populations of dorsal spinal neurons that express both Kvβ2 and Kv1 α-subunit genes and 2) the 24- and 48-h developmental period, during which IKvundergoes developmental regulation. At both 24 and 48 h, antisense methods produced efficient knock-down of both Kvβ2 protein and IKv. At both times, dominant negative suppression of Kv1 channels also eliminated IKv, indicating that Kv1 channels require Kvβ2 subunits to function in dorsal spinal neurons. Even though Kv1 channels determined the IKvvalues of both dorsal neuron types, comparisons of their IKvproperties revealed important differences at both developmental stages. The latter results support the notion that different Kv1 α-subunits and/or posttranslational modifications underlie the IKvvalues of the two dorsal neuron types. Overall, the results demonstrate that Kvβ2 subunits function in vivo as obligatory subunits of Kv1 channels in at least two neuron types and two different developmental stages.
Evaluation of Image Analysis to Determine the N‐Fertilizer Demand of Broccoli Plants (Brassica oleracea convar. botrytis var. italica)
Authors: Graeff Simone , Pfenning Judit , Claupein Wilhelm , Liebig Hans-Peter
Published: August 2008

Numerous models have been developed for calculating optimum decision rules for nitrogen fertilization based on remote sensing techniques. New technologies related to digital image analysis may provide an alternative method to estimate nutrient status faster and more efficiently than current techniques. A series of field studies was conducted to determine the applicability of digital image analysis for nitrogen demand estimates in broccoli plants. Digital images were taken under constant light conditions in various wavelength ranges (380–1300 nm) using a digital imager. Images were processed for the parameters a∗ and b∗ in the L∗a∗b∗ color system. The image analysis showed a close correlation between the nitrogen status of broccoli plants and the parameter b∗ of the L∗a∗b∗ color system especially in the wavelength ranges 510780 and 516780 nm. The relationship between nutrient concentration in leaf dry matter and the parameters b∗ was used to determine the N fertilizer demand within the cultivation period. Estimated N amounts were applied as top dressing four weeks after setting and were 100 kg ha−1 lower than the standard fertilizer rate. Calculated N balances indicated a total uptake of applied N amounts in the image‐based N treatments without considerable yield loss. Thus, digital image analysis proved to be an effective means of determining nitrogen status and adjusting fertilizer applications to preserve or enhance crop quality and yield considering sustainability.
Aflatoxin-Related Immune Dysfunction in Health and in Human Immunodeficiency Virus Disease
Authors: Jiang Yi , Jolly Pauline E. , Preko Peter , Wang Jia-Sheng , Ellis William O. , Phillips Timothy D. , Williams Jonathan H.
Published: August 2008

Both aflatoxin and the human immunodeficiency virus (HIV) cause immune suppression and millions of HIV-infected people in developing countries are chronically exposed to aflatoxin in their diets. We investigated the possible interaction of aflatoxin and HIV on immune suppression by comparing immune parameters in 116 HIV positive and 80 aged-matched HIV negative Ghanaians with high (≥0.91 pmol/mg albumin) and low (<0.91 pmol/mg albumin) aflatoxin B1 albumin adduct (AF-ALB) levels. AF-ALB levels and HIV viral load were measured in plasma and the percentages of leukocyte immunophenotypes and cytokine expression were determined using flow cytometry. The cross-sectional comparisons found that (1) among both HIV positive and negative participants, high AF-ALB was associated with lower perforin expression on CD8+ T-cells (P=.012); (2) HIV positive participants with high AF-ALB had significantly lower percentages of CD4+ T regulatory cells (Tregs;P=.009) and naive CD4+ T cells (P=.029) compared to HIV positive participants with low AF-ALB; and (3) HIV positive participants with high AF-ALB had a significantly reduced percentage of B-cells (P=.03) compared to those with low AF-ALB. High AF-ALB appeared to accentuate some HIV associated changes in T-cell phenotypes and in B-cells in HIV positive participants.
Overcoming GlutathioneS-Transferase P1–Related Cisplatin Resistance in Osteosarcoma
Authors: Pasello Michela , Michelacci Francesca , Scionti Isabella , Hattinger Claudia Maria , Zuntini Monia , Caccuri Anna Maria , Scotlandi Katia , Picci Piero , Serra Massimo
Published: August 2008

Cisplatin (cis-diamminedichloroplatinum, CDDP) is one of the most used drugs for osteosarcoma chemotherapy. By using a series of CDDP-resistant variants, which were established from the U-2OS and Saos-2 human osteosarcoma cell lines, we found that CDDP resistance was mainly associated with the increase of both the intracellular level and enzymatic activity of glutathione S-transferase P1 (GSTP1). On the basis of these findings, we evaluated the clinical effect of GSTP1 in a series of 34 high-grade osteosarcoma patients and we found that the increased expression of GSTP1 gene was associated with a significantly higher relapse rate and a worse clinical outcome. These indications prompted us to assess the in vitro effectiveness of 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX), a promising new anticancer agent that is a highly efficient inhibitor of GSTP1. NBDHEX was tested on a panel of 10 human osteosarcoma cell lines and 20 variants of the U-2OS or Saos-2 cell lines that were resistant to CDDP, doxorubicin, or methotrexate. NBDHEX proved to be very active on the vast majority of these cell lines, including those with higher GSTP1 levels and enzymatic activity. Drug combination studies showed that NBDHEX can be used in association with CDDP and provided useful information about the best modality of their combined administration. In conclusion, our findings show that GSTP1 has a relevant effect for both CDDP resistance and clinical outcome of high-grade osteosarcoma and that targeting GSTP1 with NBDHEX may be considered a promising new therapeutic possibility for osteosarcoma patients who fail to respond to conventional chemotherapy. [Cancer Res 2008;68(16):6661–8]
Sensitization to the Lysosomal Cell Death Pathway by Oncogene-Induced Down-regulation of Lysosome-Associated Membrane Proteins 1 and 2
Authors: Fehrenbacher Nicole , Bastholm Lone , Kirkegaard-Sørensen Thomas , Rafn Bo , Bøttzauw Trine , Nielsen Christina , Weber Ekkehard , Shirasawa Senji , Kallunki Tuula , Jäättelä Marja
Published: August 2008

Expression and activity of lysosomal cysteine cathepsins correlate with the metastatic capacity and aggressiveness of tumors. Here, we show that transformation of murine embryonic fibroblasts with v-H-ras or c-srcY527F changes the distribution, density, and ultrastructure of the lysosomes, decreases the levels of lysosome-associated membrane proteins (LAMP-1 and LAMP-2) in an extracellular signal-regulated kinase (ERK)- and cathepsin-dependent manner, and sensitizes the cells to lysosomal cell death pathways induced by various anticancer drugs (i.e., cisplatin, etoposide, doxorubicin, and siramesine). Importantly, K-ras and erbb2 elicit a similar ERK-mediated activation of cysteine cathepsins, cathepsin-dependent down-regulation of LAMPs, and increased drug sensitivity in human colon and breast carcinoma cells, respectively. Notably, reconstitution of LAMP levels by ectopic expression or by cathepsin inhibitors protects transformed cells against the lysosomal cell death pathway. Furthermore, knockdown of either lamp1 or lamp2 is sufficient to sensitize the cells to siramesine-induced cell death and photo-oxidation–induced lysosomal destabilization. Thus, the transformation-associated ERK-mediated up-regulation of cysteine cathepsin expression and activity leads to a decrease in the levels of LAMPs, which in turn contributes to the enhanced sensitivity of transformed cells to drugs that trigger lysosomal membrane permeabilization. These data indicate that aggressive cancers with high cysteine cathepsin levels are especially sensitive to lysosomal cell death pathways and encourage the further development of lysosome-targeting compounds for cancer therapy. [Cancer Res 2008;68(16):6623–33]
Loss of the CBX7 Gene Expression Correlates with a Highly Malignant Phenotype in Thyroid Cancer
Authors: Pallante Pierlorenzo , Federico Antonella , Berlingieri Maria Teresa , Bianco Mimma , Ferraro Angelo , Forzati Floriana , Iaccarino Antonino , Russo Maria , Pierantoni Giovanna Maria , Leone Vincenza , Sacchetti Silvana , Troncone Giancarlo , Santoro Massimo , Fusco Alfredo
Published: August 2008

Using gene expression profiling, we found that the CBX7 gene was drastically down-regulated in six thyroid carcinoma cell lines versus control cells. The aims of this study were to determine whether CBX7 is related to the thyroid cancer phenotype and to try to identify new tools for the diagnosis and prognosis of thyroid cancer. We thus evaluated CBX7 expression in various snap-frozen and paraffin-embedded thyroid carcinoma tissues of different degrees of malignancy by quantitative reverse transcription-PCR and immunohistochemistry, respectively. CBX7 expression progressively decreased with malignancy grade and neoplasia stage. Indeed, it decreased in an increasing percentage of cases going from benign adenomas to papillary (PTC), follicular, and anaplastic (ATC) thyroid carcinomas. This finding coincides with results obtained in rat and mouse models of thyroid carcinogenesis. CBX7 loss of heterozygosity occurred in 36.8% of PTC and in 68.7% of ATC. Restoration of CBX7 expression in thyroid cancer cells reduced growth rate, with a retention in the G1 phase of the cell cycle, suggesting that CBX7 can contribute to the proliferation of the transformed thyroid cells. In conclusion, loss of CBX7 expression correlates with a highly malignant phenotype in thyroid cancer patients. [Cancer Res 2008;68(16):6770–8]
Drug Delivery with Carbon Nanotubes forIn vivoCancer Treatment
Authors: Liu Zhuang , Chen Kai , Davis Corrine , Sherlock Sarah , Cao Qizhen , Chen Xiaoyuan , Dai Hongjie
Published: August 2008

Chemically functionalized single-walled carbon nanotubes (SWNT) have shown promise in tumor-targeted accumulation in mice and exhibit biocompatibility, excretion, and little toxicity. Here, we show in vivo SWNT drug delivery for tumor suppression in mice. We conjugate paclitaxel (PTX), a widely used cancer chemotherapy drug, to branched polyethylene glycol chains on SWNTs via a cleavable ester bond to obtain a water-soluble SWNT-PTX conjugate. SWNT-PTX affords higher efficacy in suppressing tumor growth than clinical Taxol in a murine 4T1 breast cancer model, owing to prolonged blood circulation and 10-fold higher tumor PTX uptake by SWNT delivery likely through enhanced permeability and retention. Drug molecules carried into the reticuloendothelial system are released from SWNTs and excreted via biliary pathway without causing obvious toxic effects to normal organs. Thus, nanotube drug delivery is promising for high treatment efficacy and minimum side effects for future cancer therapy with low drug doses. [Cancer Res 2008;68(16):6652–60]
Erythropoietin inhibits apoptosis induced by photodynamic therapy in ovarian cancer cells
Authors: Solár Peter , Koval Ján , Mikeš Jaromír , Kleban Ján , Solárová Zuzana , Lazúr Ján , Hodorová Ingrid , Fedoročko Peter , Sytkowski Arthur J.
Published: August 2008

Recombinant human erythropoietin is widely used to treat anemia associated with cancer and with the myelosuppressive effects of chemotherapy, particularly platinum-based regimens. Erythropoietin is the principal regulator of erythroid cell proliferation, differentiation, and apoptosis. Recently, the antiapoptotic and proliferative effects of erythropoietin on nonhematopoietic cells were also established. We now show the effect of erythropoietin treatment on the response of A2780 and SKOV3 ovarian carcinoma cell lines to photodynamic therapy (PDT) using hypericin. SKOV3 exhibited an increased resistance to hypericin when cells were treated with erythropoietin. This resistance was reversed by treatment of SKOV3 cells with the specific Janus kinase 2 kinase inhibitor AG490 or the tyrosine kinase inhibitor genistein. These results support a role for the specific erythropoietin-induced Janus kinase 2/STAT signal transduction pathway in PDT resistance. Evidence of erythropoietin signaling was obtained by the demonstration of Akt phosphorylation in both A2780 and SKOV3 cells. Erythropoietin-treated SKOV3 cells exhibited decreased apoptosis induced by hypericin, an effect that was blocked by the phosphoinositide 3-kinase/Akt inhibitor wortmannin. These results may have important implications for ovarian cancer patients undergoing PDT and receiving erythropoietin. [Mol Cancer Ther 2008;7(8):2263–71]
Upper Ocean Turbulence from High-Resolution 3D Simulations
Authors: Klein Patrice , Hua Bach Lien , Lapeyre Guillaume , Capet Xavier , Le Gentil Sylvie , Sasaki Hideharu
Published: August 2008

The authors examine the turbulent properties of a baroclinically unstable oceanic flow using primitive equation (PE) simulations with high resolution (in both horizontal and vertical directions). Resulting dynamics in the surface layers involve large Rossby numbers and significant vortical asymmetries. Furthermore, the ageostrophic divergent motions associated with small-scale surface frontogenesis are shown to significantly alter the nonlinear transfers of kinetic energy and consequently the time evolution of the surface dynamics. Such impact of the ageostrophic motions explains the emergence of the significant cyclone–anticyclone asymmetry and of a strong restratification in the upper layers, which are not allowed by the quasigeostrophic (QG) or surface quasigeostrophic (SQG) theory. However, despite this strong ageostrophic character, some of the main surface properties are surprisingly still close to the surface quasigeostrophic equilibrium. They include a noticeable shallow (≈k−2) velocity spectrum as well as a conspicuous local spectral relationship between surface kinetic energy, sea surface height, and density variance over a large range of scales (from 400 to 4 km). Furthermore, surface velocities can be remarkably diagnosed from only the surface density using SQG relations. This suggests that the validity of some specific SQG relations extends to dynamical regimes with large Rossby numbers. The interior dynamics, on the other hand, strongly differ from the surface dynamics, involving a small Rossby number, a steep (≈k−4) velocity spectrum, and a somewhat steeper density spectrum. The compensation of the surface restratification by a destratification at depth confirms a connection between the surface and the interior induced by the small-scale divergent motions.
Decadal Sea Level Variability in the South Pacific in a Global Eddy-Resolving Ocean Model Hindcast
Authors: Sasaki Yoshi N. , Minobe Shoshiro , Schneider Niklas , Kagimoto Takashi , Nonaka Masami , Sasaki Hideharu
Published: August 2008

Sea level variability and related oceanic changes in the South Pacific from 1970 to 2003 are investigated using a hindcast simulation of an eddy-resolving ocean general circulation model (OGCM) for the Earth Simulator (OFES), along with sea level data from tide gauges since 1970 and a satellite altimeter since 1992. The first empirical orthogonal function mode of sea level anomalies (SLAs) of OFES exhibits broad positive SLAs over the central and western South Pacific. The corresponding principal component indicates roughly stable high, low, and high SLAs, separated by a rapid sea level fall in the late 1970s and sea level rise in the late 1990s, consistent with tide gauge and satellite observations. These decadal changes are accompanied by circulation changes of the subtropical gyre at 1000-m depth, and changes of upper-ocean zonal current and eddy activity around the Tasman Front. In general agreement with previous related studies, it is found that sea level variations in the Tasman Sea can be explained by propagation of long baroclinic Rossby waves forced by wind stress curl anomalies, if the impact of New Zealand is taken into account. The corresponding atmospheric variations are associated with decadal variability of El Niño–Southern Oscillation (ENSO). Thus, decadal sea level variability in the western and central South Pacific in the past three and half decades and decadal ENSO variability are likely to be connected. The sea level rise in the 1990s, which attracted much attention in relation to the global warming, is likely associated with the decadal cooling in the tropical Pacific.
Influence of Large-Scale Flow Regimes on Cool-Season Precipitation in the Northeastern United States
Authors: Archambault Heather M. , Bosart Lance F. , Keyser Daniel , Aiyyer Anantha R.
Published: August 2008

The influence of large-scale flow regimes on cool-season (November–April) northeastern U.S. (Northeast) precipitation is investigated for the period 1948–2003 from statistical and synoptic perspectives. These perspectives are addressed through (i) a statistical analysis of cool-season Northeast precipitation associated with the North Atlantic Oscillation (NAO) and Pacific–North American (PNA) regimes (one standard deviation or greater NAO or PNA daily index anomalies persisting several days), and (ii) a composite analysis of the synoptic signatures of major (two standard deviation) 24-h cool-season Northeast precipitation events occurring during NAO and PNA regimes. The statistical analysis reveals that negative PNA regimes are associated with above-average cool-season Northeast precipitation and an above-average frequency of light and moderate precipitation events, whereas the opposite associations are true for positive PNA regimes. In comparison with PNA regimes, NAO regimes are found to have relatively little influence on the amount and frequency of cool-season Northeast precipitation. The composite analysis indicates that a surface cyclone flanked by an upstream trough over the Ohio Valley and downstream ridge over eastern Canada and upper- and lower-level jets in the vicinity of the Northeast are characteristic signatures of major cool-season Northeast precipitation events occurring during NAO and PNA regimes. Negative NAO and positive PNA precipitation events, however, are associated with a more amplified trough–ridge pattern and greater implied Atlantic moisture transport by a low-level jet into the Northeast than positive NAO and negative PNA precipitation events. Furthermore, a signature of lateral upper-level jet coupling is noted only during positive and negative PNA precipitation events.
Seasonal Influence of the Quasi-Biennial Oscillation on Stratospheric Jets and Rossby Wave Breaking
Authors: Hitchman Matthew H. , Huesmann Amihan S.
Published: August 2008

The influence of the stratospheric quasi-biennial oscillation (QBO) on the polar night jets (PNJs), subtropical easterly jets (SEJs), and associated Rossby wave breaking (RWB) is investigated using global meteorological analyses spanning 10 recent QBO cycles. The seasonal dependence of the descent of the QBO is shown by using five layered shear indices. It is found that the influence of the QBO is distinctive for each combination of QBO phase, season, and hemisphere (NH or SH). The following QBO westerly (W) minus easterly (E) differences in the PNJs were found to be significant at the 97% level: When a QBO W (E) maximum is in the lower stratosphere (∼500 K or ∼50 hPa), the NH winter PNJ is stronger (weaker), in agreement with previous results (mode A). Mode A does not appear to operate in other seasons in the NH besides DJF or in the SH in any season. When a QBO W (E) maximum is in the middle stratosphere (∼700–800 K or ∼10–20 hPa), the PNJ in the SH spring is stronger (weaker), also in agreement with previous results (mode B). It is found that mode B also operates in the NH spring. A third distinctive mode is found during autumn in both hemispheres: a QBO W (E) maximum in the middle stratosphere coincides with a weaker (stronger) PNJ (mode C). The signs of wind anomalies are the same at low and high latitudes for modes A and B, but are opposite for mode C. This sensitive dependence on QBO phase and season is consistent with the nonlinear nature of the interaction between planetary waves and the shape of the seasonal wind structures.

During the solstices the meridional circulation associated with QBO connects primarily with the winter hemisphere, whereas during the equinoxes it is more symmetric about the equator. QBO W enhance the equatorial potential vorticity (PV) gradient maximum, but the time-mean maximum may be related to chronic instabilities in the subtropics. The equatorial PV gradient maximum and flanking RWB tend to be more pronounced in the Eastern Hemisphere in stratospheric analyses.

When QBO W are in the middle stratosphere, the flanking PV gradient minima (SEJs) are enhanced and RWB is more frequent and symmetric about the equator. When QBO W are in the upper stratosphere, a strong seasonal asymmetry is seen, with enhanced RWB in the summer SEJ, primarily during boreal winter. This is consistent with an upward increase of summer to winter flow and modulation by a strong “first” and weak “second” semiannual oscillation.