O radiologista considerou o aspeto compatível com depósitos secundários hepáticos de tumor primitivo não evidente nesse exame. Havia efetuado colonoscopia total que não revelou alterações e uma endoscopia digestiva alta que identificou uma papila de Vater procidente. find more Por esta razão, foi submetido a ecoendoscopia que confirmou a existência da mesma, mas sem aspeto neoplásico, e identificou a volumosa massa hepática no lobo direito, ultrapassando os limites do campo ecográfico, de ecotextura heterogénea e com outros nódulos contíguos

de menores dimensões. Foi efetuada punção transduodenal com resultados inconclusivos. Aquando do internamento, o doente apresentava-se consciente, orientado e colaborante, com pele e mucosas coradas, hidratadas e anictéricas, com bom estado geral, hemodinamicamente estável, febril (38 °C) e sem adenomegálias. A auscultação cardiopulmonar não revelou alterações. O abdómen apresentava uma hepatomegalia dolorosa e os membros inferiores ligeiro edema bilateral. Na avaliação laboratorial à entrada, encontrou-se anemia normocítica (Hb 9 g/dl; VR 11,7-16), leucocitose com neutrofilia (leucócitos 11,5 G/L;

VR 4,3-11), hipoprotrombinémia (58%; VR 70-120), aumento das enzimas de colestase (GGT 317 U/l, FA 373 U/l; MG-132 VR 30-120) com bilirrubina normal, hipoalbuminémia (3,1 g/dl; VR 3,5-5,2) e aumento da PCR (23,02 mg/dl; VR < 0,5). Na gasometria era patente uma hipoxemia ligeira e na eletroforese das proteínas, um pico duvidoso na fração monoclonal gama. Os marcadores tumorais (CEA, CA 19,9, alfa-fetoproteína) eram normais. A ferritina apresentava-se aumentada (1363 ng/ml; VR 10-300) e saturação de transferrina diminuídas (6%; VR 20-50). As serologias dos vírus da hepatite A, B e C foram negativas, bem como a pesquisa de CMV, EBS, HSV 1 e 2. A indagação

de doenças 6-phosphogluconolactonase infecciosas (nomeadamente Coxiella burnetti, Borrelia burgdorferi, Rickettsia conorii, sífilis, brucelose) e parasitoses (amebíase e quisto hidático) foram similarmente negativas. A ecografia hepática (fig. 1) revelou volumosa formação sólida, hipoecoénica, heterogénea e lobulada, com 19 cm de maior eixo, ocupando o lobo direito até ao segmento iv. O estudo Doppler mostrou a veia porta com fluxo hepatópeto, com velocidades aumentadas a nível do ramo direito; artéria hepática permeável com velocidades altas, principalmente no ramo direito, e com um ramo nutritivo para a lesão tumoral. A TC evidenciou (Figura 2 and Figura 3) várias formações nodulares hepáticas, a maior ocupando o segmento IV com cerca de 16 × 12 cm, com áreas hipodensas (prováveis zonas de necrose), sofrendo moderado efeito de realce em fase arterial, mantendo-se nas fases subsequentes (portal e tardia).

Among all male variants, 52% consisted in transitions (A/G and C/T), while 32% were transversions (A/T, A/C, G/T, C/G) (Fig. 3). Meanwhile, 623 variants were detected in females, of which, 85% were SNVs. Among all female variants, 55% consisted in transitions while 31% were transversions INCB024360 solubility dmso (Fig. 3). The full list of SNPs identified for males and females is provided in Table S3 and Table S4, respectively. This study was funded by FONDEFD09I1256 and FONDAP15110027 from CONICYT-Chile.

“
“Phytoplankton accounts for less than 1% of the photosynthetic biomass on Earth, yet is estimated to contribute half of the world’s net primary production (Field et al., 1998). A minor fraction of the phytoplankton biomass sinks to the sea floor and, if not decomposed in the sediment, can end up as kerogen, the source of future oil and gas reservoirs (Kirchman et al., 2009). The vast majority however is rapidly consumed by higher organisms selleck chemicals such as protists, copepods and fish as well as by the prokaryotic fraction of the plankton, the so-called bacterioplankton. Bacterioplankton hence plays a pivotal role in the recycling of phytoplankton biomass and thus controls a substantial fraction of the global carbon flux (Kirchman et al., 2009) in a process that is known as the ‘microbial loop’ (Davies et al., 2012).

Marine phytoplankton is comprised of photosynthetic bacteria such as cyanobacteria, but the bulk of its biomass consists of uni- to pluricellular algae like diatoms and haptophytes. ID-8 Bacterial communities that decompose algal biomass in the pelagic zone are diverse and consist of different heterotrophic taxa with varying ecological strategies (Giovannoni and Stingl, 2005). Several studies based on culture-independent 16S ribosomal RNA gene sequence (16S rDNA) analysis have provided insights into these communities in terms of composition (Gilbert et al., 2012, Romano et al., 2005, Verslyppe

et al., 2010 and Verslyppe et al., 2013), but little is known about the dynamics and functional interactions within such communities. Transcriptome-based approaches have been used in several studies to tackle these questions (Gilbert et al., 2008, Hewson et al., 2009, Poretsky et al., 2005, Poretsky et al., 2009, Poretsky et al., 2010 and Vila-Costa et al., 2010), but it is still not fully understood, how a multitude of eukaryotic and prokaryotic planktonic species coexist in a seemingly homogenous habitat with limited resources (Glöckner and Kottmann, 2011). The relationships between these species range from mutualism to competition and even predation (Romano et al., 2005). Algicidal bacteria are known to affect algal bloom dynamics (Mayali and Azam, 2004), and vice-versa algae release compounds that inhibit bacterial growth (Ribalet et al., 2008). Hence there are plenty of reasons why species get extinct by competition and only a limited number of highly competitive species should prevail.

; Indianapolis, IN, USA) [11]. Data are expressed as the mean ± SEM. The statistical significance of difference in mean values between TGR

and SD rats was assessed by unpaired Student’s t-test or two-way ANOVA (glucagon and pyruvate challenge tests). Significance level was set at p < 0.05. Twelve weeks old TGR rats (0.0269 ± 0.00067 g/g BW) showed no difference in liver weight corrected by body weight when compared with SD rats. (0.0265 ± 0.00047 g/g BW) as illustrated in Fig. 1. Glucagon stimulation test also not demonstrate statistical difference between fasted UK-371804 molecular weight TGR rats and SD rats (Fig. 2). Analysis of basal hepatic glycogen measurement showed no variation between TGR (0.4005 ± 0.1562 mg/g) and SD rats (0.5825 ± 0.1778 mg/g) as demonstrated in Fig. 2. In order to evaluate the gluconeogenesis pathway we performed the pyruvate challenge test (Fig. 1). Pyruvate administration in fasting TGR showed a decrease in the synthesis of glucose in these rats compared Cytoskeletal Signaling inhibitor to the SD with the minimum peak for glycemic values of the curve in TGR rats at 30 min (106.8 in SD vs. 85.73 in TGR; P < 0.01) and 45 min (117.0 in SD vs. 98.00 in TGR; P < 0.01). To understand the molecular mechanisms underlying changes in gluconeogenesis and glycogenolysis

we analyzed the levels of glycongen phosphorylase enzyme, PYGB/L/M by Western blotting method (Fig. 2). The total of PYG enzyme level was not altered (4.148 ± 0.6282 in TGR vs. 5.893 ± 0.4164 in SD rats). In addition, real-time PCR analysis revealed a marked decrease in PEPCK expression in TGR hepatic tissue (1.403 ± 0.1441 in SD vs. 0.4598 ± 0.2391 in TGR), without difference in G6Pase expression in TGR and SD rats (0.7363 ± 0.09964

in SD vs. 1.133 ± 0.2475 in TGR) as showed in Fig. 1. In order to confirm the downregulation in gluconeogenesis we evaluated the mRNA expression of HNF-4α, responsible for the regulation of transcription enzymes on gluconeogenesis pathway (Fig. 1), and we observed an important decrease in TGR rats (0.7214 ± 0.1196 in TGR vs. 1.307 ± 0.2023 in SD). It is well documented that Ang-(1-7) presents several effects opposite to those produced by Ang II [13], [15], [20], [22] and [23], however, this is the first study evaluating the role of Ang-(1-7) on liver gluconeogenesis and glycogenolysis. The main result of the present study was Axenfeld syndrome to show that transgenic rats with increased circulating Ang-(1-7) presents a decreased activation of the gluconeogenesis pathway, demonstrated by the pyruvate challenge test accompanied by a significantly reduction in PEPCK and HNF4α. The role of Ang II in glucose metabolism is well established. Coimbra et al. [4] demonstrated that administration of Ang II increases hepatic glucose output, mostly by activation of gluconeogenesis pathway in comparison to the glycogenolysis pathway. The present results point to a counterregulatory action of Angiotensin-(1-7) on gluconeogenesis, which opposes the effect of Ang II.

Fees for certification seem to be aimed at consolidated operations7 and producers

likely selling to niche export markets (unlike coffee or cocoa, certified seafood has not yet been mainstreamed into consumer consciousness with mislabeling of seafood being of significant concern). VietG.A.P. may be an appropriate starting point for many producers, since certification fees will initially be covered by the Vietnamese government. Even so, officials suggest that adoption of these guidelines would add between 20% and 25% to the cost of production [47], and it is unclear if NVP-BEZ235 or when producers will receive a premium for their product (the Ministry of Agriculture and Rural Development has signaled that they would ensure that VietG.A.P. certified products fetch higher prices than their uncertified counterparts [47]). All this suggests that significant implementation challenges exist for both producers and certifiers within a context such as Vietnam. To ground our overview of certification we turn to our study site in central Vietnam. The Tam Giang Lagoon is the largest brackish-water lagoon in Southeast Asia, covering 22,000 ha and spanning 70 km of Hue׳s coastline [31]. Lagoon physiography makes it ideal for fishing and aquaculture activities. Around 300,000 people, representing one third of the provincial population,

live in the three districts surrounding the lagoon, with see more an estimated 100,000 people depending directly on the fisheries sector and another 200,000 people depending on a range of related livelihood activities including coastal agriculture and occasional fishing or fish farming activities [32]. Fish farming is small producer oriented, using various methods

(net enclosures found in the lagoon scape, and highland and lowland earth ponds found near or at the edge of the lagoon). Small producers have been involved in intensive tiger shrimp culture (P. monodon) particularly in the 1990s and occasional intensive whiteleg shrimp culture (L. vannamei) in the 2000s. Extensive or improved-extensive tiger shrimp mixed with a combination of mud crabs, freshwater carp and other fish species have predominated since the mid 2000s in an effort to control disease outbreaks [48]. A total Gemcitabine purchase of 5,321 t of aquaculture was produced in Hue province in 2010. Much of this volume was produced in the lagoon district in which we focus (Phu Vang produced over 2000 t of aquaculture in 2010) [25]. Phu Vang district also has higher than average poverty rates (13% in Phu Vang versus 11% throughout Hue province), and a high population density (612 km2 compared with 215 km2 in Hue province generally). To better understand what aquaculture looks like in Phu Vang district, Table 3 highlights key characteristics found amongst our sample (primary livelihood activity, main species targeted, total land area, and income).

The animals were then food deprived for 56 h (IACUC approved), a time length previously shown to maximize food hoarding [4] and [18]. Before access to food was returned at light offset, half of the animals received an injection of PYY(3-36) (0.1 nmol in 200 nl), the active form of the peptide for satiation [52], into the GSK-3 cancer Arc and the other half received the saline vehicle. Wheel revolutions,

food foraging, food intake, and food hoarding were measured at 1, 2, 4, 24 h and each day post-injection until all animals returned to pre-injection levels. After the animals returned to behavioral baseline, brain tissue was collected to verify cannula location (Fig. 1; 69 hits and 11 misses or removed their cannula; final group sizes: PYY(3-36): BW: n = 12, FW: n = 11, and 10REV: n = 13 and vehicle: BW: n = 9, FW: n = 11, and 10REV: n = 13). Raw data from Experiment 1 were transformed for each individual into percent change from vehicle before

statistical analyses using the formula: [((X-Vehicle)/Vehicle) × 100], where “X” equals the value measured in response to the dose of BIIE0246 FLT3 inhibitor and “Vehicle” equals the value measured for that individual after vehicle injection. No statistical comparisons were made among the time intervals because the intervals were of unequal duration. No statistical comparisons are reported across test days in this counterbalanced-within subject design, as repeated measures two-way ANOVA (foraging treatment × Arc-injection) showed no effect of injection order. The data were analyzed using a two-way ANOVA (foraging treatment × Arc-injection; 3 × 4). For Experiment Niclosamide 2, data were not transformed into percent change from

vehicle, because animals only were food deprived once and therefore could not serve as their own control, and the absolute values were analyzed using a two-way ANOVA (foraging treatment × Arc-injection; 3 × 2) within each individual time point for the same reason as above. All statistical analyses were performed using NCSS (version 2007, Kaysville, UT). Exact probabilities and test values were omitted for simplicity and clarity of presentation. Differences were considered statistically significant if P < 0.05. Tukey-Kramer Multiple Comparison Tests were used for post hoc tests when appropriate. Misplaced cannulae were not included in the final statistical comparisons. Wheel running. At each time interval, Arc injection of BIIE0246 did not significantly stimulate wheel running activity compared to vehicle injection at any of the three doses tested (0.1, 1.0 and 5.0 nmol; Fig. 2A). The lack of wheel running increase in the FW group, where food delivery was not contingent upon wheel running, suggests that there was not non-specific stimulation of locomotor activity. Food foraging.

This analysis revealed a significant increase in activity on trials where BE occurred as early as 2–4 sec following the first scene onset (collapsed across hemisphere: HC t = 2.11, p = .02; PHC t = 1.94, p = .03), indicating that this is an early response that likely occurred soon after stimulus onset ( Fig. 5A and B). Given that the shortest delay between the onset of the first and second scene presentations was 3.45 sec (occurring on one third of the trials due to the jittered delay), we can conclude with some certainty that this effect during the 2–4 sec time-window can only be attributed to a process occurring in response to the first scene.

Furthermore, given that the BOLD signal lags behind cognitive processes with a peak response at around 6 sec after stimulus presentation, this early response at 2–4 sec suggests a rapid response to the first stimulus. Due to the limited temporal resolution of fMRI, Trametinib cell line Lumacaftor manufacturer it is not possible to determine whether the signal can be attributed to a process occurring online, during perception of the scene, or shortly after the stimulus offset. Nevertheless, we can conclude that the BE-related activity occurred in response to the first scene, prior to the onset of the second scene, which was the critical question of interest here. These results clearly implicate both the HC and PHC in BE. Our hypothesis

was that the HC plays a central role in the BE effect, because patients with damage localised to the HC show reductions in BE (Mullally et al., 2012). It was therefore important to tease apart the functional contributions of these two regions by investigating the neural dynamics occurring during the BE effect. If our hypothesis was correct, then we would expect the HC to be driving the activity of the PHC. The flow of information between these two regions was assessed using DCM (see Section 2.8), a Bayesian model comparison method in which different models of the neural dynamics are compared in order to find the most likely model of information flow in

the brain (Friston et al., 2003). For this analysis, we used a simple approach which involved investigating PD184352 (CI-1040) the connectivity between the two ROIs, the HC and PHC. We conducted this analysis separately in both hemispheres, and used a random effects Bayesian model comparison method to determine which was the winning model (Stephan et al., 2009, 2010). The winning model was the backward modulation model, in which the HC drove activity within the PHC, and this was the case for both hemispheres independently (exceedance probability for the backward model was 60% in the right, and 51% in the left hemisphere; Fig. 5C). This result suggests that the HC is the driving force behind the BE effect, which then influences activity within the PHC.

CL Brener clone T. cruzi epimastigotes were maintained axenically at 28 °C in LIT medium supplemented with 10% fetal calf serum (FCS) with weekly transfers. Four-day old cultures at the mid-log phase of growth were used in all experiments. The tissue culture trypomastigotes were obtained from the supernatants of 5- to 6-day old infected LLC-MK2 cells that were maintained in RPMI-1640 medium supplemented with 2% FCS for 5–6 days at 37 °C in a 5% humidified CO2 atmosphere, as previously described

( Adade et al., 2011). The intracellular amastigotes were obtained and cultured PI3K inhibitor as described below. The melittin peptide was purchased from Sigma Chemical Co. (St. Louis, MO, USA). A stock solution (250 μg/ml) was prepared in phosphate-buffered saline (PBS, pH 7.2) and stored at −20 °C until further use.

We initially relied on the data obtained from the trypanocidal activity of A. mellifera crude venom ( Adade et al., 2012) to define the ranges of melittin concentrations to be tested. The epimastigotes were resuspended in LIT medium at a concentration of 1 × 106 cells/ml and incubated with 1.34–5.36 μg/ml of melittin in a 24-well plate (Nunc Inc., Naperville, IL, USA). They were then incubated for 96 h at 28 °C. The number of parasites was determined daily PCI-32765 datasheet by counting formalin-fixed parasites in a hemocytometer. The parameter used to estimate the inhibition of proliferation was the IC50, which represents the drug concentration that inhibited 50% of cell growth. The parasites grown medroxyprogesterone in drug-free LIT medium were used as controls. The growth experiments were carried out in triplicate, and the standard deviation of the cell densities at each time point was presented with error bars. The cell viability was verified by the detection of propidium iodide staining by flow cytometry (described below). The tissue culture trypomastigotes (1 × 106 cells/ml) were resuspended

in RPMI media (Sigma) containing 10% FCS and incubated with 0.1–0.4 μg/ml of melittin in a 96-well plate (Nunc Inc.). This was followed by incubation at 37 °C. The LD50 parameter (50% trypomastigote lysis) was evaluated by counting the formalin-fixed parasites in a hemocytometer after 24 h. The experiments were performed in triplicate. The uninfected LLC-MK2 cells were seeded in 24-well plates (Nunc Inc.) containing glass coverslips. They were maintained in RPMI media supplemented with 10% FCS and were treated or not with 1 and 5 μg/ml of melittin at 37 °C for 72 h. The cytotoxic effects were examined daily using a trypan blue exclusion test. Briefly, at the end of the incubation period, the glass coverslips were washed with sterile PBS (pH 7.2) and stained with a 1:1 dilution of trypan blue solution:RPMI for 5 min.

The overlap length of the two amplicons was 149 bp. Two fragments of this candidate gene were amplified by PCR in two separate PCR reactions, of which the volumes were 15 μL containing 30 ng DNA, 150 nmol L− 1 of each primer, 1 × Pfu polymerase reaction buffer, 1.5 or 2.0 mmol L− 1

MgCl2, 0.2 mmol L− 1 of each dNTP, and 0.5 U Pfu polymerase. After initial denaturation at 95 °C for 6 min, 34 cycles were conducted at 95 °C for 1 min, primer-specific annealing temperatures at 58 °C for 1 min, Z-VAD-FMK ic50 72 °C for 1 min, and a final extension step at 72 °C for 10 min. PCR products were then separated by polyacrylamide gel electrophoresis. The band of interest was cut out from the gel with a razor blade. The gel slice was soaked and crushed briefly in ddH2O, and the water was used as template for a second PCR. The second PCR products were directly sequenced by the Sunny Sequencing Service (Sunny, Shanghai, China). Amplicons of each accession

were sequenced with both forward and reverse PCR primers. Sequence reads were checked and assembled into contigs. The sequences of AF512540 and AY189969 were used as the reference sequences. The sequence reads were aligned using ClustalW2.1 [23] and manually corrected using BioEdit [24]. Sequence polymorphisms were deduced from sequence comparisons in gene-wise sequence alignments. Reference sequences were excluded from all subsequent analyses, and InDels were treated MG-132 mouse as single polymorphic sites. Nucleotide diversity (π), haplotype identification, haplotype diversity (Hd) and LD were determined with software DnaSP v5.10

[25]. Analyses of π and Hd were performed separately for each species as well as for full populations. Population structure was inferred from SSR data with Structure version 2.2 [26]. We used prior population information, predefining accessions as belonging to specific populations. Accessions were defined as 1) G. arboreum accessions, 2) G. barbadense accessions, and 3) G. hirsutum accessions. The optimum number of populations Oxalosuccinic acid (K) was selected after five independent runs with a burn-in of 500,000 iterations followed by 500,000 iterations testing for K = 2 to K = 10. Structure produced a Q matrix that lists the estimated membership coefficients for each accession in each cluster. The estimated Q matrices were used in the subsequent AM, by logistic regression, performed in TASSEL software [27]. SNPs or InDels at site frequencies of 0.05 or greater among the 92 accessions were evaluated using TASSEL. Mean phenotypic values were applied for the association analysis. One thousand permutations of the data were run to account for multiple testing, and a significant association was assigned if the P-value of the most significant polymorphism in a region was seen in < 5% of the permutations. We analyzed DNA polymorphisms in the Exp2 genomic region in 92 Gossypium accessions.

, 2000). Bubien et al. (2004), using this peptide, inhibited

Na+ currents in high-grade human GSK2118436 molecular weight astrocytoma cells (glioblastoma multiforme, or GBM). However, when the same experiment was performed on normal human astrocytes, the toxin failed to inhibit the whole-cell current, suggesting that Psalmotoxin 1 may be used in the diagnosis as well as in therapeutic treatments of malignant gliomas. Gao et al. (2005a) studied the inhibitory effect of the venom of the spider Macrothele raveni on the proliferation of human hepatocellular carcinoma cell line BEL-7402 and its molecular mechanism. Using the MTT assay, the venom was shown to inhibit cell proliferation in a dose- and time-dependent manner,

with IC50 of 20 μg/ml (48 h), also inhibiting DNA synthesis by the treated cells. Flow cytometry analyses showed an arrest in the cell cycle in the G(0)/G(1) phase and an increase in the number of apoptotic cells. Furthermore, the expression of c-myc, a transcription factor responsible for activation of a large number of genes, was down-regulated. McLachlan et al., 2005 and Kekre et al., 2005 and Siedlakowski et al. (2008) studied the effects of Pancratistatin (PST) upon human neuroblastoma cells (SHSY-5Y), human lymphoma (Jurkat) and breast cancer (MCF-7), respectively. PST, a natural molecule isolated from the lily spider Pancratium littorale, was shown to have apoptotic effects specifically upon these cells, and not upon their homologous non-tumoral lines. The most interesting finding is that this molecule does not affect normal MS-275 cells when compared to other drugs employed in clinical treatments of cancer, such as Etoposide (Vp-16) and Paclitaxel (Taxol). In cancer cell lines, PST induced permeabilization of mitochondria and activation Janus kinase (JAK) of caspases, leading cells to apoptosis and also increasing ROS production, while the mitochondria of normal cells were not affected. It is worth mentioning that PST induced apoptosis in cancer cells acting upon non-genomic targets (with no DNA damage) and,

even more remarkable is the fact that this molecule does not seem to have any effect upon non-cancer cells, representing an important candidate in the development of anti-cancer therapies with no toxic consequences to the organism. The anti-tumor activity of gomesin, a potent anti-microbial peptide isolated from hemocytes of the spider Acanthoscurria gomesiana, was tested in vitro and in vivo ( Rodrigues et al., 2008). C57BL/6 mice received subcutaneous injection of 105 melanoma cells B16F10-Nex2 followed by topic treatment with gomesin as a cream, which significantly reduced tumor growth and increased survival compared to control. Gomesin displayed cytotoxic effects, reducing the viability of a number of tumor cell lines, such as melanoma, breast cancer and colon carcinoma.

The size of the targets varied from trial to trial. Stimulus size might not only be considered a pure physical property. A large object (e.g., a large animal) may be more important (and potentially e.g., more dangerous) than a small object. A very similar argument may hold true for

eccentricity. A more laterally presented object may tend to elicit an orienting response (e.g., an eye movement toward the object). The GSK126 mouse argument here is that some global physical stimulus features (such as size, eccentricity and color) may already represent a ‘pop-out’ characteristic that elicits reflexive attention and a larger P1. Another interesting question is the following: What happens when two stimulus categories are very similar (or even identical) at the level of global stimulus Venetoclax order features (such as spatial frequency, size, contrast, orientation and second order image statistics) and differ primarily (or even only) at the level of specific features? As an example let us consider the study by Busch et al. (2006a) who used color pictures of familiar, natural objects and unfamiliar ‘nonsense’ objects as targets and non-targets respectively. Unfamiliar objects were obtained by distorting the images of natural objects in a way that spatial frequencies were matched. This resulted in unfamiliar pictures having a very similar ‘stimulus-surface’ as familiar objects with

respect to color and figural elements. The interesting finding of this study was that P1 amplitude differences between familiar Baricitinib and unfamiliar objects were abolished. This finding is consistent with the suggested hypothesis that the P1 reflects early categorization which is based on global stimulus feature. If global stimulus features are very similar between the respective stimulus categories,

the P1 amplitudes will also be of similar size. The earlier discussed findings from Busch et al. (2006b) allow for an even more straight forward interpretation. Large and small targets were defined on the bases of the same stimulus property (orientation of the grating). Despite differences in target size, P1 amplitudes were identical in amplitude size. It should also be emphasized that behaviorally significant changes in P1 can be observed that are independent of stimulus features. As an example, in a speeded reaction time task, Fründ et al. (2007) observed significant changes in P1 amplitude sizes, although the same stimulus (a black square) was presented in all trials. Subjects were instructed to respond with a button press as quickly as possible. To keep them motivated, they received feedback about response latency. Trials were sorted with respect to response speed. P1 amplitude was significantly larger in trials with short response latencies. The interpretation is that fluctuations in attentional top down control during stimulus perception underlie the observed differences in P1 amplitude.