Animal and clinical studies have demonstrated that oxidative stress, a common pathophysiological factor in cardiac disease, reduces repolarization reserve by enhancing the L-type calcium current, the late Na, and the Na-Ca exchanger, promoting early afterdepolarizations (EADs) that can initiate ventricular tachycardia and ventricular fibrillation (VT/VF) in structurally remodeled hearts. Increased ventricular fibrosis plays a key facilitatory role in allowing oxidative-stress induced EADs to manifest as triggered activity and VT/VF, since normal non-fibrotic hearts are resistant to arrhythmias when challenged with similar or higher levels of oxidative stress. The findings imply that antifibrotic therapy, in addition to therapies designed to suppress EAD formation at the cellular level, may be synergistic in reducing the risk of sudden cardiac death. Ca−L) to allow ICa−L to recover from inactivation and gain sufficient amplitude to evoke a propagated wavefront causing premature ventricular complex (PVC). In other words, the time constants of Ca and K currents have to be in resonance with each other for voltage oscillations underlying EADs to occur  led him to describe triggered activity this way: “Extrasystolic arrhythmias could develop under conditions that augment the negative after-potential, such as an increase in the extracellular calcium concentration, aconitine, veratrine, adrenaline, and digitalis” . He described the resulting triggered activity as “battement auto-entretenu du coeur” (self-sustained beating of the heart)   dynamics and conduction velocity (CV) restitution in promoting APD alternans , where the steady state ICa−L activation and inactivation curves overlap, but can occur only when the activation of time-dependent outward currents, particularly IKs, is delayed as in the setting of reduced repolarization reserve  and the rate constant of activation of the delayed rectifier K current (IK) were varied. The Hopf-homoclinic bifurcation sequence required that the time constants of these currents were properly matched   further prolonged APD but suppressed EAD-mediated triggered activity  is much more arrhythmogenic than APD prolongation in which the AP maintains a high plateau voltage , ICa−L, and the Na-Ca exchanger to favor the formation of EADs  pump   in the regulatory domain of CaMKII which removes the auto-inhibition of the enzyme by freeing the catalytic site causing sustained CaMKII activity even in the absence of Ca2+/CaM  was reduced by premature electrical stimulation  and middle aged rabbit (~5–6 years old) hearts, using high resolution optical mapping for cardiac activation pattern and glass microelectrode cellular recordings from selected left ventricular (LV) epicardial sites. Aging-related fibrosis is apparent in these two species and manifested high degree of heterogeneity in its distribution being very dense in the endocardium with intermediate levels fibrosis on the anterior and posterior LV wall as shown in Figure 2O2 or ATII readily promoted EADs and triggered activity that led to VT and then to VF  was needed to promote propagated EADs. That is either too few or too many number of coupled fibroblasts prevented the genesis (too few) or propagation (too many) of the EADs. A “critical” level of fibrosis was needed for both initiation and the propagation of the EAD to cause arrhythmias  , and coincides in time with the reactivation kinetics of ICa−L in patients with chronic heart failure , endothelin-1 (ET-1), connective tissue growth factor (CTGF), ATII, and platelet-derived growth factor (PDGF) networks Leask, . Much ofCa−L reactivation, drugs that shift the voltage dependence of steady-state activation and inactivation to reduce the amplitude of ICa−L window currents could potentially suppress EAD formation without adversely affecting normal excitation-contraction coupling. Similarly, specific blocker of the late INa current can also be useful in suppressing EADs as block of late Na channel openings does not interfere with excitation-contraction coupling. Finally, interventions designed to suppress oxidative stress or inhibit CaMKII activation in the setting chronic heart disease could also play a role.It is hoped that the basic research findings will be translated into clinical strategies to reduce cardiac arrhythmia risk in patients with heart disease. Antifibrotic therapy seems to hold great promise, as the independent role of fibrosis in the genesis of VT/VF is becoming increasingly recognized. Drugs directly targeting EAD formation may also be identified, now that the dynamical mechanisms involved have been clearer. For example, given the key role of IThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Callosal axon projections are among the major long-range axonal projections in the mammalian brain. They are formed during the prenatal and early postnatal periods in the mouse, and their development relies on both activity-independent and -dependent mechanisms. In this paper, we review recent findings about the roles of neuronal activity in callosal axon projections. In addition to the well-documented role of sensory-driven neuronal activity, recent studies using in utero electroporation demonstrated an essential role of spontaneous neuronal activity generated in neonatal cortical circuits. Both presynaptic and postsynaptic neuronal activities are critically involved in the axon development. Studies have begun to reveal intracellular signaling pathway which works downstream of neuronal activity. We also review several distinct patterns of neuronal activity observed in the developing cerebral cortex, which might play roles in activity-dependent circuit construction. Such neuronal activity during the neonatal period can be disrupted by genetic factors, such as mutations in ion channels. It has been speculated that abnormal activity caused by such factors may affect activity-dependent circuit construction, leading to some developmental disorders. We discuss a possibility that genetic mutation in ion channels may impair callosal axon projections through an activity-dependent mechanism. For developmental neuroscientists, interhemispheric axons  have been an excellent model to study how long-range axonal projections develop in the brain. Callosal axons form one of the major axonal tracts in the mammalian brain, the corpus callosum, which visibly connects the two cerebral hemispheres. In the past decades, detailed anatomical and physiological studies in animal models have improved our understanding of the organization and development of callosal connections –8. Recen2+ imaging and multiunit recordings have uncovered several distinct patterns of neuronal activity occurring in neonatal mouse cortex during the periods when callosal axon projections develop . Th. Th41]. 2+ signaling. It is known that Ca2+ plays a critical role in the regulation of neuronal morphogenesis including dendrite and axon development [2+. Ageta-Ishihara and colleagues showed that a member of the Ca2+-dependent kinase family, Ca2+/calmodulin-dependent protein kinase Iα  (CaMKIα), plays a critical role in callosal axon projections [α specifically impaired axonal, but not dendritic, growth of cortical neurons. They also found that activation of GABAA receptors promoted axonal growth in a CaMKIα-dependent manner. They further showed that in vivo RNAi knockdown of CaMKIα in callosal projection neurons by in utero electroporation disturbed their axonal projections. It is known that the action of GABA is excitatory in the neonatal period (until two weeks of age) [α is critically involved in activity-dependent callosal axon projections and that this activity is at least in part mediated by excitatory action of GABA. What intracellular signaling mediates activity-dependent axonal development? Kir2.1 overexpression in cortical neurons hyperpolarizes their membrane potential and increases the threshold for evoking action potentials, thereby inhibiting the firing activity , 40, 52.elopment –73. Therjections . Using i of age) . Althougα is an important player which may work downstream of neuronal activity, but other possible candidates  remain unexplored. In addition, these intracellular signaling molecules would influence the regulation of cytoskeletal proteins, thereby regulating growth and branching of axons, but the precise molecular mechanism is unknown. It is important to note that some of intracellular signaling molecules might work both activity dependently and independently: for example, they may be involved in midline crossing of callosal axons under the control of some guidance molecules and subsequently play a role in axon arbor growth and branching under the control of neuronal activity. If this is the case, intricate experiments such as those using temporally controlled RNAi knockdown of target molecule would be necessary.Many issues remain to be addressed. For example, the work of Ageta-Ishihara and colleagues suggests that CaMKIAnother important issue to be addressed would be the possible relationship between the process of thalamocortical projections and that of the formation of callosal connections. In the visual cortex during the neonatal period, the activity of cortical neurons is modulated by thalamocortical inputs, which transmit activity from the periphery  , 76. ThaRecent studies have revealed that several distinct patterns of neuronal activity take place in the rat/mouse cortex during the periods when callosal axon projections develop , 83–85. 2+ imaging technique to monitor neuronal activity in the developing cortical circuits in a slice preparation [2+ waves traveled across cortical slices taken from P1–P4 rats and named them cortical early network oscillations (cENOs). cENOs were typically observed once per 1–12 minutes, and many neurons  participated in the wave. cENOs were completely blocked by AMPA-and NMDA-type glutamate receptor antagonists but not by GABA receptor antagonists, suggesting that cENOs are driven by glutamatergic transmission. Later, by using a similar approach, Allène and colleagues reported another synapse-driven network pattern in neonatal cortical slices, named giant depolarizing potentials (GDPs) [2+ waves have been observed in vivo rat/mouse cerebral cortex [Garaschuk and colleagues used Caparation , and latparation , 49. Thes (GDPs) . GDPs arl cortex , 48–50, 2+ activity mentioned above mostly reflects neuronal firings [μm. The precise relationship between the two types of Ca2+ waves (cENOs and GDPs) and the three types of electrical activities  is to be clarified.Correlated Ca firings . Extrace firings , 87, 88. firings . SpindleAll three types of electrical activity can be elicited by activation of the periphery. For example, in the somatosensory cortex, tactile, or electrical stimulation of whiskers can induce these network activities . It has Interestingly, spindle-bursts and gamma oscillations are sometimes synchronized between hemispheres . In thisThe activity of individual cortical neurons and cortical network can be modulated by environmental factors. For example, the emergence of cENOs and GDPs is influenced by experimental conditions such as anoxia and aglycemia . Some co+ channels crucial for the regulation of excitability in cortical neurons, and its genetic mutations are responsible for neonatal epilepsy  [The activity of cortical neurons and network can also be modulated by genetic factors. For example, genetic mutations in ion channels may affect excitability of neurons, causing some diseases such as epilepsy. KCNQ2 is a type of Ks: BFNC) –99. All s: BFNC) . Transges: BFNC) . Anothers: BFNC) . In boths: BFNC) , implyins: BFNC) , 103.To test the idea that activity-dependent callosal axon projections may be affected by mutations in ion channels, we examined the effect of expression of a dominant-negative KCNQ2 mutant channel on callosal axon projections. As shown in Callosal connections mediate interhemispheric communication. They serve to integrate and coordinate information between hemispheres, thus involved in higher cognitive functions. Malformations such as partial or complete agenesis of the corpus callosum are associated with many human congenital disorders , 111, anDuring development of callosal connections, both activity independent and dependent mechanisms are involved. Many genetic factors responsible for the activity independent processes have been reported , but “ac2+ imaging techniques have enabled us to monitor neuronal activity in neonatal cerebral cortical circuits. These new techniques will be useful to examine how cortical activities are modulated by genetic and environmental factors. Hypo-or hyperactivity in neonatal cortical circuits caused by these factors may induce abnormality in the cortical architecture including the corpus callosum. In addition, genetic techniques such as in utero electroporation will allow us to identify molecular signals critical for activity-dependent callosal axon projections. Future work would link the factors that disturb activity-dependent callosal connection formation, with those that influence the patterns of neuronal activity in the developing cortex.Recent advancements in electrophysiological and Ca


Molecular imaging of the spine is a rarely used diagnostic method for which only a few case reports exist in the literature. Here, to the best of our knowledge we present the first case of a combination of molecular imaging by single photon emission computer tomography and positron emission tomography used in post-operative spinal diagnostic assessment.We present the case of a 50-year-old Caucasian woman experiencing progressive spinal cord compression caused by a vertebral metastasis of a less well differentiated thyroid cancer. Following tumor resection and vertebral stabilization, total thyroidectomy was performed revealing follicular thyroid carcinoma pT2 pNxM1 . During follow-up our patient underwent five radioiodine therapy procedures (5.3 to 5.7 GBq each) over a two-year period. Post-therapeutic I-131 scans showed decreasing uptake in multiple Pulmonary metastases. However, following an initial decrease, stimulated thyroglobulin remained at pathologically increased levels, indicating further neoplastic activity. F18 Fludeoxyglucose positron emission tomography, which was performed in parallel, showed remaining hypermetabolism in the lungs but no hypermetabolism of the spinal lesions correlating with the stable neurological examinations. While on single photon emission computer tomography images Pulmonary hyperfixation of I-131 disappeared (most likely indicating dedifferentiation), there was persistent spinal hyperfixation at the operated level and even higher fixation at the spinal process of L3. Based on the negative results of the spinal F18 fludeoxyglucose positron emission tomography, a decision was made not to operate again on the spine since our patient was completely asymptomatic and the neurological risk seemed to be too high. During further follow-up our patient remained neurologically stable.Molecular imaging by F18 fludeoxyglucose positron emission tomography helps to exclude metabolically active spinal metastases and to spare further risky surgery. Fluorine-18 fludeoxyglucose (FDG) positron emission tomography (PET) is a well established diagnostic modality for standard oncological staging, restaging, and treatment monitoring evaluations, and has a major impact on patient management . A key i131I whole-body scan results -FDG) and post-therapeutic SPECT I-131). Clinically and neurologically our patient was stable over three years of follow-up. Post-therapeutic radioiodine scans showed decreasing uptake in most Pulmonary lesions but remaining uptake in spine lesions  an1. ClinicAfter thorough interdisciplinary discussion, despite the remaining I-131 uptake it was decided not to operate again on our patient's spine as she was completely asymptomatic; conventional imaging also remained stable and the neurological risk seemed to be too high for the thoracic level. During further follow-up our patient remained neurologically stable.Detection of spinal metastasis by MI is a relatively new, but clinically important technique. Cases such as our patient's, where the different MI modalities can be directly compared, are important to gain more experience in the different modalities for spinal MI and to perhaps find special indications for the one or the other method. In addition, our case report underlines the usefulness of FDG-PET in assessing the metabolic activity of bone metastasis of less well differentiated thyroid cancer.In our case report, in which different MI techniques were used for the detection of distant metastases from thyroid cancer, we were able to demonstrate different behavior of the pulmonary and osseous lesions. While the pulmonary nodes presented with decreased radioiodine uptake but increased FDG uptake indicating de-differentiation, the spinal lesions showed stable radioiodine uptake without FDG uptake, most probably indicating stable disease. Subsequently, integrated I-131 SPECT/CT was found to have an additional value compared to planar scintigraphy in patients with thyroid cancer for correct characterization of equivocal tracer uptake seen on planar imaging, as well as for precise localization of malignant lesions in the skeleton ,9. In ouThe FDG-PET examinations were performed under stimulated TSH conditions to increase the diagnostic sensitivity. It is known that TSH stimulates thyrocyte metabolism, glucose transport and glycolysis. Since FDG is a glucose analog, several studies have shown that recombinant human TSH (rhTSH) stimulation improves the detection of occult thyroid metastases with FDG-PET, compared with scans performed on TSH suppression . Beyond The presence of bone metastases alters the prognosis of patients with differentiated thyroid carcinoma. Our case report underlines the fact that FDG-PET can have an important impact on management in patients with thyroid cancer.Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.The authors declare that they have no competing interests.NS, GP, MO and BS analyzed and interpreted the data from our patient regarding the neurosurgical disease and the molecular. MET performed the histological examination of the kidney, and together with NS, GP, MO, BA, TS and BS was a major contributor to writing the manuscript. All authors read and approved the final manuscript.


Spontaneous iliac arteriovenous fistulae are a rare clinical entity. Such localized fistulation is usually a result of penetrating traumatic or iatrogenic injury. Clinical presentation can vary greatly but commonly includes back pain, high-output congestive cardiac failure and the presence of an abdominal bruit. Diagnosis, therefore, is often incidental or delayed.We report a case of a spontaneous ilio-iliac arteriovenous fistula in a 68-year-old Caucasian man detected following presentation with unilateral claudication and congestive cardiac failure. Following computed tomography evaluation, the fistula was successfully treated with a combined endovascular (aorto-uni-iliac device) and open  approach.Endovascular surgery has revolutionized the management of such fistulae and we report an interesting case of a high-output iliac arteriovenous fistulae successfully treated with a hybrid vascular approach. Spontaneous iliac arteriovenous fistulae (AVF) are a rare clinical entity. Such localized fistulation is usually a result of penetrating traumatic or iatrogenic injury . ClinicaA 68-year-old Caucasian man was referred to our out-patients clinic following the incidental discovery of a 6 × 8 cm distended iliac vessel whilst having an ultrasound for surveillance of liver cirrhosis. His clinical history revealed a progressive history of right flank pain, worsening right leg claudication and a persistently cold sensation in his right foot. He also complained of progressive breathlessness on exertion, clinically suggestive of deteriorating CCF. There was no history of trauma or previous surgery. Ankle-brachial pressure measurements revealed a reduced index of 0.76 on the right, and a normal index of 1.35 on the left with corresponding toe pressures of 55 mmHg and 143 mmHg respectively. A contrast enhanced computed tomography (CT) scan showed an isolated right common iliac artery (CIA) to right common iliac vein AVF (Figure Pre-operative discussions focused on finding an endovascular strategy to solve the problem. As no normal caliber proximal right CIA existed, an isolated iliac covered stent was impossible as no proximal sealing zone existed. This required sealing a proximal stent in his aorta. Bifurcated endografts have been used to seal ilio-iliac fistulae previously . The aorOn the first postoperative day, the mass was no longer pulsatile and the machinery-like murmur in the right iliac fossa was absent. A CT scan on postoperative day two confirmed a patent AUI endovascular graft and patent femoro-femoral bypass, as well as confirming exclusion of contrast from the right iliocaval system Figure . His rigPenetrating traumatic injury remains the most common cause of abdominal and pelvic arteriovenous fistulae . This trTreatment of iliac AVFs in the open vascular surgical era was fraught with danger, with reported surgical mortality rates of 9-34%. Operative blood loss of six liters was common . Acute pThe evolution of endovascular surgery has led to a paradigm shift in the approach to managing aneurysmal disease with a concomitant vast reduction in mortality and morbidity rates. The first endovascular exclusion of an iliocaval fistula appeared in 1995 . We add Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.The authors declare that they have no competing interests.GOB was the main author, treated our patient, researched the topic and coordinated the editing of the paper. CM & ZM were major contributors to researching, writing and editing the paper. NH, MPC, PM, DM & SON were all involved in making treatment decisions regarding our patient as well as reading, making editorial suggestions and approving the final manuscript. All authors read and approved the final manuscript.


Several studies have reported optimal population decoding of sensory responses in two-alternative visual discrimination tasks. Such decoding involves integrating noisy neural responses into a more reliable representation of the likelihood that the stimuli under consideration evoked the observed responses. Importantly, an ideal observer must be able to evaluate likelihood with high precision and only consider the likelihood of the two relevant stimuli involved in the discrimination task. We report a new perceptual bias suggesting that observers read out the likelihood representation with remarkably low precision when discriminating grating spatial frequencies. Using spectrally filtered noise, we induced an asymmetry in the likelihood function of spatial frequency. This manipulation mainly affects the likelihood of spatial frequencies that are irrelevant to the task at hand. Nevertheless, we find a significant shift in perceived grating frequency, indicating that observers evaluate likelihoods of a broad range of irrelevant frequencies and discard prior knowledge of stimulus alternatives when performing two-alternative discrimination. An attractive view on human information processing proposes that inference problems are dealt with in a statistically optimal fashion. This hypothesis can explain aspects of perception, movement planning, cognition and decision making. In the present study, I use a new psychophysical paradigm that reveals surprisingly suboptimal perceptual decision making. Observers discriminate between two sinusoidal gratings of a different spatial frequency. Making use of visual noise, I induce an asymmetry in neural population responses to the gratings and find this asymmetry to effectively bias perceptual decision making. A simple ideal observer model, uninformed about the presence of visual noise but only considering the two grating spatial frequencies relevant to the task at hand, manages to avoid such a bias. I conclude that observers are limited in their ability to make use of prior knowledge of relevant visual features when performing this task. These results are in line with a growing number of findings suggesting that near-optimal decoders, although straightforward to implement and achieving near-maximal performance, consistently overestimate empirical performance in simple perceptual tasks. Perceptual decisions in a wide range of visual tasks ultimately rely on information encoded in neural responses in primary visual cortex (V1). However, this information may not be readily available to higher levels of the visual system because it is distributed across entire populations of neurons. Moreover, each neuron's reliability is limited by intrinsic response variability and its relevance strongly depends on the perceptual task in which the organism is engaged. To form accurate perceptual judgements, the brain thus needs to pool sensory responses efficiently, decoding the population response into a reliable decision variable.A wide range of psychophysical and physiological studies have investigated population decoding efficiency in simple visual tasks such as two-alternative detection and discrimination A crucial issue concerns the neural implementation of optimal population decoding. Formally, optimal decoding requires to evaluate neural responses probabilistically by computing the (log) likelihood function. This function captures the likelihood that specific stimuli gave rise to the observed population response. Theoretical work has shown that, under certain conditions, the necessary part of the log likelihood function can be obtained through simple linear combination of neural responses Here, we estimate the width of the likelihood read-out functions involved in two-alternative pattern detection and discrimination by modeling a new perceptual bias. We measured grating detectability and discriminability in the presence of filtered visual noise and found that filtered noise backgrounds dramatically alter the perception of grating spatial frequency. Embedding a grating in low-pass filtered noise causes the perceived spatial frequency of the grating to decrease, while high-pass filtered noise increases perceived grating spatial frequency. A population code model is proposed, consisting of a physiologically inspired V1 encoding front-end followed by a decoding stage. By simultaneously modeling grating detectability and discriminability, we were able to estimate both the amount of sensory information encoded in the V1 population response as well as the extent to which this information is used to maximize performance. While filtered visual noise induces an asymmetry in the likelihood function, an ideal observer only evaluates the likelihood of exactly the two possible stimuli and is thus not affected by this asymmetry. Therefore, the observed bias indicates severely suboptimal decoding which we assign to an imprecise read-out of the likelihood function. Only when read-out functions as broad as 4 octaves are assumed, the model accounts for all behavioural measurements. These findings suggest that observers failed to sample the likelihood function at the appropriate locations with arbitrary high precision and consequently, that precision pooling was not adopted in our tasks.We measured the effect of filtered noise on perceived spatial frequency in a two-alternative two-interval discrimination task. One grating was embedded in low-pass or high-pass filtered 1-D noise (cut-off at 5.5 cycles per degree) while another grating was presented in unfiltered, broadband noise . By varyIn the former conditions (hereafter referred to as the main conditions), low-pass noise significantly decreased perceived standard grating spatial frequency . The read-out function displayed in To evaluate the performance of an ideal observer implementing optimal decoding, we reduced the width of the model's read-out functions to an infinitely small value while keeping all other parameters at the best-fitting values. Under these conditions, the predicted perceptual bias disappears and discrimination performance increases from 84% to 95% correct . Such high performance might discourage the use of an unbiased yet possibly more demanding decoding strategy. Furthermore, the performance gain that can be obtained using a more optimal decoding scheme is limited. As the observed high performance is due to a considerable number of unbiased stimulus conditions, we conducted a similar discrimination experiment and only included stimulus conditions in which the bias was particularly strong see . Observetraining .In the present study, we report a new perceptual bias. Filtered visual noise significantly alters the perception of two known gratings in a two-alternative spatial frequency discrimination task, shifting perceived spatial frequency to lower and higher frequencies in respectively low-pass and high-pass filtered noise conditions. The fact that we observed such a strong bias is not self-evident. Observers received extensive training prior to the start of the experiments and auditory feedback was provided after each trial. Furthermore, we informed observers of the veridical grating spatial frequencies via noise-free grating templates presented at the beginning of each trial block. It should be noted that the bias cannot be attributed to merely a low signal-to-noise ratio, preventing observers from detecting the gratings when embedded in visual noise. Gratings were presented at relatively high contrasts in the discrimination experiment, corresponding to the 84%-correct detection thresholds measured in broadband noise. Moreover, the fact that we measured high overall performance and correspondingly steep psychometric functions in the discrimination task indicates that observers base their decisions -at least partially- on the veridical grating spatial frequency.We propose a population code model, consisting of a physiologically inspired encoding front-end followed by a simple linear decoder. The best-fitting model accurately predicts the perceptual bias in the discrimination task while simultaneously capturing contrast detection performance in the absence of visual noise, in broadband noise as well as in filtered notched noise using a single set of parameters. Although few constraints were imposed, the estimates of the encoding stage parameters lie close to values reported in macaque or cat V1 single-cell recording studies. Ideal observer analysis revealed that a considerable amount of spatial frequency information is available in the encoding stage, even in the presence of filtered visual noise. Furthermore, using this information to achieve unbiased spatial frequency discrimination does not require complex decoding. A biologically plausible linear decoder While our unified suboptimal likelihood read-out scheme for contrast detection and spatial frequency discrimination accounts for all behavioural measurements, our data are not inconsistent with optimal read-out in the contrast detection task. However, previous studies To read out the likelihood function with high precision, the visual system requires a-priori knowledge of the grating spatial frequencies presented on each trial in the discrimination experiment. In other words, the brain has to be able to represent appropriate, narrow signal templates. A theoretical issue concerns whether and how such templates can be reliably implemented in populations of noisy and broadly-tuned neurons. Recurrent network models have been proposed, capable of removing noise from the population response and representing arbitrarily small templates with high accuracy Our model differs from traditional psychophysical models of early visual encoding of gratings embedded in external noise Various studies have measured psychophysical two-alternative detection and discrimination performance while simultaneously determining the amount of sensory information encoded by early visual brain areas. A common finding, consistent with our results, is that simple decoding schemes, while straightforward to implement and achieving near-optimal performance, consistently overestimate empirical performance Perceptual biases are usually interpreted as a hallmark of optimal statistical inference Stimuli were presented on a carefully linearized monochrome Siemens SMM 21106 LS monitor with white phosphor (P-45). Spatial resolution was 996×777 pixels at 130 Hz and 8-bit luminance precision was obtained at each contrast level used in the experiments. Viewing distance was 124 cm, corresponding to a pixel size of 0.0181 degrees of visual angle. The experiment was run in a darkened room, with the display's mean background luminance equal to 47.5 Three observers  participated in two spatial frequency discrimination experiments. Two observers (RV and NV) participated in a contrast detection experiment. All observers but TP were naive to the purpose of the experiments. Observers received extensive training prior to data collection and had normal or corrected-to-normal vision.Stimuli were Gabor gratings, consisting of a horizontally-orientated sinusoidal grating subtending 9.2 degrees of visual angle, multiplied by a 2-D circularly-symmetrical Gaussian envelope with a standard deviation of 3.7 degrees of visual angle. A set of 1-D horizontally-orientated noise images was generated by sampling pixel luminance values from a Gaussian distribution centred at mean luminance. Mean noise-power density equalled A two-alternative two-interval forced-choice (2-AFC) procedure was used to measure spatial frequency discrimination performance in the presence of broadband and filtered visual noise. On each trial, a fixation cross was presented for 250 ms which disappeared 500 ms before the onset of auditory-cued 50 ms stimulus intervals. One interval contained a grating of 5.5 c/deg (the standard grating). The other interval contained a grating of variable spatial frequency (the comparison grating). Observers indicated the interval containing the grating of the highest spatial frequency. Auditory feedback was provided after each trial. In the main conditions, the standard grating was embedded in low-pass or high-pass filtered noise with a cut-off at 5.5 c/deg while the comparison grating was presented in broadband noise. Control conditions in which comparison instead of standard grating was embedded in filtered noise were included to prevent the use of the noise conditions as discrimination cues. In addition, we included two conditions in which both gratings were presented either in broadband noise or in the absence of noise. All noise conditions were randomly intermixed. High-contrast, noise-free templates of standard and comparison gratings were presented at the beginning of each block of 50 trials, within which comparison spatial frequency was kept constant. Eight comparison frequencies, sampled logarithmically between 1.9 and 15.6 c/deg, were tested in a first discrimination experiment. The relative matching frequency, corresponding to the comparison frequency yielding a choice proportion of 50%, was determined by fitting cumulative Weibull psychometric functions using a maximum-likelihood fitting procedure A similar 2-AFC procedure was used to measure contrast detection performance in the absence of visual noise and in the presence of broadband and notched noise. In the no-noise condition, one interval contained a blank while the target interval contained a grating of 5.5 c/deg, i.e., the spatial frequency of the standard grating in the discrimination task as well as the average spatial frequency of all gratings presented in the discrimination experiments. In the noise conditions, both intervals contained a different background noise image. Observers were instructed to indicate the target interval and received auditory feedback after each trial. The grating was presented at one of sixteen (in the no-noise and broadband noise conditions) or nine (in the notched noise condition) fixed contrast levels. Noise and contrast conditions were randomized across trials. A high-contrast, noise-free template was presented at the beginning of each trial block. Cumulative Weibull psychometric functions were fitted to the data using a maximum-likelihood fitting procedure i to a sinusoidal grating of spatial frequency c embedded in noise background N is given by the following equation:t equalled the stimulus presentation time (in seconds). i, while i. These responses are obtained using a linear convolution of the 1-D spatial frequency amplitude spectrum of a grating or (filtered) noise background and a Gaussian-shaped tuning function. It should be noted that we normalized the linear filter responses to a full-contrast grating to equal one across all grating spatial frequencies  log likelihood can be obtained through linear precision pooling. To compute the log likelihood of spatial frequency k determining response variance was set to 1.5 A limited number of parameters were fixed at physiologically plausible values. Our data did not provide sufficient constraints to estimate these parameters. Most importantly, changing the exact values of these parameters does not affect the conclusions of the present study. More specifically, Figure S1Weighting profile (TIF)Click here for additional data file.Figure S2Off-looking when discriminating two close-together grating spatial frequencies (TIF)Click here for additional data file.Figure S3Relationship between likelihood read-out precision and precision pooling. Left: read-out functions used to obtain the discrete likelihood of spatial frequency (TIF)Click here for additional data file.Figure S4Individual data for the discrimination task. Data of the main and control conditions are provided respectively in the top and bottom row. Red, green and blue colors respectively denote low-pass filtered, white and high-pass filtered noise conditions. Full lines represent the best-fitting Weibull psychometric functions.(TIF)Click here for additional data file.Figure S5Individual data for the detection task. Dark gray, light gray and green colors respectively denote the no-noise, notched noise and white noise conditions. Full lines represent the best-fitting Weibull psychometric functions.(TIF)Click here for additional data file.Figure S684%-correct detection thresholds in broadband noise for different grating spatial frequencies. Full lines indicate the best-fitting second-degree polynomial contrast sensitivity functions. Blue, green and red colors respectively represent the data of subject KT, BM and TP. The broken line denotes the average contrast used in the discrimination tasks. This contrast was used to simulate discrimination performance.(TIF)Click here for additional data file.Figure S7Predicted discrimination performance for the constrained model (left panel) and unconstrained model (right panel) when a Fano factor of 1 (dotted lines) instead of 1.5 (full lines) was assumed. Other parameters were kept at the best-fitting values.(TIF)Click here for additional data file.Figure S8Predicted detection performance for the constrained model (left panel) and unconstrained model (right panel) when a Fano factor of 1 (dotted lines) instead of 1.5 (full lines) was assumed. Other parameters were kept at the best-fitting values.(TIF)Click here for additional data file.Text S1Supporting text providing a detailed description of the population decoding model.(PDF)Click here for additional data file.Text S2Supporting text discussing inter-individual differences and data pooling.(PDF)Click here for additional data file.Text S3Supporting text discussing contrast sensitivity across spatial frequency.(PDF)Click here for additional data file.Text S4Supporting text discussing the role of across-trial neural response variability.(PDF)Click here for additional data file.


To the Editor: Proventricular dilatation disease (PDD) is a fatal disease in psittacines that jeopardizes critical species conservation projects, such as that involving the Spix’s macaw (Cyanopsitta spixii), the world’s most endangered bird species , which has been detected in affected psittacines  (cycle threshold 31.41) and the other a red-crowned Amazon  (cycle threshold 35.1). None of the investigated embryos demonstrated histopathologic lesions typical of an ABVinfection. IHC testing did not show any positive results. However, in the ABV-positive Amazon embryo, an equivocal result was obtained.In 2 of the 30 embryos investigated, ABV RNA was detected by using the 1034 PCR. The repeated procedure provided the same results in the same embryos. One embryo was a Major Mitchell cockatoo (The swab specimens of both parents of the Major Mitchell cockatoo tested positive for ABV RNA, but serum did not demonstrate specific ABV antibodies. The crop swab specimen of the female red crowned Amazon was positive for ABV RNA, but serum was negative for ABV antibodies; the male bird tested negative by PCR but demonstrated an ABV-specific antibody titer of 80.,These results highlight the potential risk for vertical transmission of ABV and the conclusion that ABV-infected parents can most likely produce infected offspring. However, test results were positive for only 2 of 30 eggs. Because potentially dead-in-shell embryos are usually further incubated by the breeder to ensure embryonic death, the possibility cannot be excluded that ABV RNA was already degraded in some cases, thus causing false-negative results. On the other hand, these eggs might have originated from ABV-negative parents. The quality of the samples might also have caused the questionable IHC results. In PDD-affected, ABV-positive flocks >30% of the birds could be infected (Whether ABV infection of the embryos was the cause of death remains unclear. Even if typical lesions were not detected, the poor quality of the material might have hidden such lesions. However, embryonic infection that does not result in embryonic death is the basic requirement for successful vertical transmission. These preliminary results warrant further studies investigating the possibility of vertical transmission by ABV-infected pairs, especially to minimize the risk for such transmission to endangered species with restricted breeding opportunities.


Psychological stress, an evolutionary adaptation to the fight-or-flight response, triggers a number of physiological responses that can be deleterious under some circumstances. Stress signals activate the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Elements derived from those systems  can impact the immune system and possible disease states. Skin provides a first line of defense against many environmental insults. A number of investigations have indicated that the skin is especially sensitive to psychological stress, and experimental evidence shows that the cutaneous innate and adaptive immune systems are affected by stressors. For example, psychological stress has been shown to reduce recovery time of the stratum corneum barrier after its removal (innate immunity) and alters antigen presentation by epidermal Langerhans cells (adaptive immunity). Moreover, psychological stress may trigger or exacerbate immune mediated dermatological disorders. Understanding how the activity of the psyche-nervous -immune system axis impinges on skin diseases may facilitate coordinated treatment strategies between dermatologists and psychiatrists. Herein, we will review the roles of the HPA axis and the sympathetic nervous system on the cutaneous immune response. We will selectively highlight how the interplay between psychological stress and the immune system affects atopic dermatitis and psoriasis. Psychological stress can trigger the activation of numerous physiological responses, including the endocrine, nervous, and immune systems –7. Nearl The concept that psychological stress impacts the health of an individual has long been postulated. Accumulating experimental evidence is beginning to delineate how stress can induce or exasperate disease processes. A comprehensive understanding of the mechanisms whereby psychological stress contributes to disease processes may deepen our understanding of the mind-body connection and may provide novel approaches to patient treatment. The skin constitutes the largest bodily organ and is bombarded daily with environmental insults including infectious and toxic agents, allergens, ultraviolet light, and mechanical damage. Therefore, the skin is equipped with innate and adaptive properties to respond to the myriad of environmental factors encountered. In addition to environmental factors, skin also appears especially responsive to psychological stressors. Indeed, a number of psychodermatologic disorders associated with stress have been reported, including (1) psoriasis, (2) atopic dermatitis, (3) pruritus, (4) alopecia areata, (5) lichen planus, and (6) rosacea . A plaus The central hypothalamic-pituitary-adrenal (HPA) axis is activated following stress signals such as 5-hydroxytryptamine , 14, aceα isoform is the predominant CRH receptor in skin and is expressed in all major cell populations of epidermis, dermis, and subcutis. By contrast, CRH-R2 is expressed predominately in hair follicles, sebaceous and eccrine glands, muscle and blood vessels [Investigations have shown that human skin expresses CRH as well as CRH receptors (CRH-R). The CRH-R1 vessels . CRH pro vessels . However vessels . In addi vessels  and uroc vessels . CRH-R1  vessels , 39 lead vessels , 41.Ito et al. have shown that human hair follicles can synthesize cortisol and that cortisol synthesis is regulated by endogenous feedback controls . Thus, t In addition to the HPA axis, the skin is highly innervated with sensory nerves that produce neurotrophins and neuropeptides. Sensory nerves derive from the dorsal root ganglion in the skin and C-fibers form the cutaneous sensory nervous system. Psychological stress leads to increased concentrations of cutaneous nerve growth factor (NGF) . NGF has The innate immune response consists of elements that contribute to the immediate and generic defense of the skin; immunological memory does not develop. By contrast, the adaptive immune response requires time for the development of a specific defense and can create immunological memory. Psychological stress has been shown to impact both innate and adaptive immune responses.The stratum corneum is terminally differentiated epidermis that forms the outer most layer of the skin. The corneocytes forming the stratum corneum arise from the underlying keratinocytes although unlike their predecessors, corneocytes, lack nuclei and most cell organelles. The intercorneocyte spaces contain high concentrations of nonpolar lipids contributing to the water impermeability of the stratum corneum. The stratum corneum plays an integral role in maintaining tissue hydration, and its mechanical or chemical disruption results in transepidermal water loss. In addition to its role in hydration, the stratum corneum is normally sloughed off, potentially removing skin microorganisms such as potential pathogens. Finally, the stratum corneum contains melanocyte-derived melanin that protects the skin from ultraviolet radiation . Denda eGarg et al. evaluated the impact of psychological stress on barrier recovery in humans . IndividStreptococcus pyogenes infections on psychologically stressed mice [β-defensin) and developed correspondingly more severe S. pyogenes cutaneous infections as compared with nonstressed control mice. Pharmacological blockade of CRH or glucocorticoid production returned antimicrobial peptides to normal levels and reduced the infection severity. Thus, psychological stress appears to be directly linked to the innate immunity conferred by antimicrobial peptides via the central or peripheral HPA axis. Skin also synthesizes and secretes antimicrobial peptides encapsulated in lamellar bodies. Aberg et al. evaluated the impact of cutaneous sed mice . Animals+ T-cell help [ Mast cells are found throughout connective tissues, including the dermis –57. ACTHell help . Systemiell help  and acutell help , 67.Mast cells also play a role in neurogenic inflammation. Singh et al. reported that restraint-induced stress resulted in significantly enhanced degranulation of mast cells in mice as compared with their nonstressed counterparts. Pretreatment of mice before stress with CRH antiserum, the neurotensin receptor antagonist SR48692 and capsaicin to deplete sensory neurons were all found to inhibit mast cell degranulation. These results suggested a role for neurogenic inflammation in psychological stress that is in addition to the HPA axis . In factThe adaptive immune response requires the interaction of antigen-presenting cells  with antigen-specific lymphocytes . Activation of lymphocytes requires their complex interplay with antigen presenting cells and co-stimulatory molecules on the surfaces of both cell types as well as the production of cytokines.Dhabhar and Mcewen investigated the impact of acute stress on contact hypersensitivity (CHS) reactions in rats using stress induced by a 2-hour confinement in a plexiglass box . BrieflyIn contrast to the results described above, Flint et al. showed that restraint stress prior to DNFB sensitization resulted in suppression of the immune response . Thus, eDifferent strains of mice may have different skin sensitivities to psychological stressors. Flint et al. reported that C57BL/6 mice had blunted ear swelling responses to restraint stress as compared with BALB/c mice . ImportaThe impact of chronic stress on skin immune responses has also been investigated. Chronic stress has been reported to lead to immunosuppression in a number of systems, including skin graft rejection . In a moAmong the factors that may account for psychological stress-induced changes in the adaptive immune response are changes in the numbers, proportions, and distributions of immune cells. Previous studies found that psychological stress markedly decreased the percentages of leukocytes in the blood , 2. InteH1/TH2 balance toward TH2 and thus impact the nature of the immune response [β2-AR with the antagonist ICI188, 551 impaired the migration of Langerhans cells to the lymph nodes and blunted the subsequent CHS response when mice were sensitized with the fluorescein isothiocyanate contact sensitizing reagent [In addition to differences in cell numbers and distributions, psychological stress may modulate the activities of immunological cells. For example, stress has been shown to impair lymphocyte function . Stress response . Importa reagent . In cont reagent . H1 T-cell clone but increased antigen presentation to a TH2 T-cell clone. Those researchers suggested that exposure of Langerhans cells to nerve-derived CGRP may polarize the immune response to a TH2 type of immunity [Neuropeptides can also impact the biological activities of antigen-presenting cells. Hosoi et al. showed that CGRP impinged on Langerhans cells in the epidermis and CGRP was directly detected on the surfaces of some Langerhans cells. Moreover, CGRP was found to inhibit the ability of Langerhans cells to present antigen in vitro . Recentlimmunity . Other nimmunity .In summary, psychological stressors and stress-related molecules  have been shown to impact various cell behaviors, costimulatory molecule expression and cytokine profiles of immune cells in skin adaptive immune responses, including dendritic cells and lymphocyte immune cell subsets. A number of skin diseases may be preceded or exacerbated by psychological stress. In the following section, we review what is known about the impact of psychological stress on atopic dermatitis and psoriasis. Our focus is on these two skin diseases because they are relatively common skin disorders.H1/TH2 T-cell response. Acute inflammation is primarily TH2 with a shift toward TH1 chronification [ Atopic dermatitis is a chronic inflammatory skin disorder characterized by eczematous lesions and pruritus. It is a common disorder affecting 6% of the population in the USA . Atopic fication , 90. Psyfication . Traumatfication .γ and a reduction in IL-4 concentrations with no significant differences between the two groups. These studies showed that immunological similarities and differences exist between atopic dermatitis patients and nonatopic individuals subjected to psychological stressors. Buske-Kirschbaum et al. analyzed leukocyte subsets, serum IgE levels, and cytokine concentrations in atopic dermatitis patients and nonatopic controls stressed in front of an audience using the Trier Social Stress Test (TSST) . Both grH1 activity potentially via IL-12, thus skewing the TH1/TH2 balance toward TH2. Thus, flares in atopic dermatitis following psychological stress may reflect TH2 skewing to acute disease symptoms.Interestingly, patients with atopic dermatitis have been shown to have reduced production of cortisol and ACTH due to experimental TSST stressors as compared with nonatopic controls. By contrast, catecholamine levels were significantly higher in atopic patients as compared with nonatopic controls. Thus, atopic dermatitis patients have blunted HPA axis reactivity as assessed by cortisol and ACTH measurements, but an overactive sympathetic adrenomedullary system as suggested by the high concentrations of catecholamine . Both th+ cell infiltrates expressed the 5-hydroxytryptamine 2A receptor and the serotonin transporter protein. Furthermore, the numbers of mast cells were significantly greater in the skin lesions as compared with uninvolved skin. Likewise, nerve fibers were found in the epidermis and papillary dermis of involved skin as compared to uninvolved skin. In contrast, the number of SP and CGRP positive nerve fibers was not significantly different between involved and noninvolved skin. Nonetheless, chronic stress was correlated with greater numbers of 5-hydroxytryptamine 2A receptor positive cells in the papillary dermis of involved skin. These results showed that atopic dermatitis results in differences in skin innervation and modulation of the serotonin system that also occurs in atopic dermatitis patients during chronic stress. Concentrations of NGF and SP are elevated in in the sera of atopic dermatitis patients. Moreover, NGF and SP concentrations have been positively correlated with disease severity , 96. RecH2-mediated disease that becomes TH1 polarized with chronicity. Atopic dermatitis seems to worsen in patients that are psychologically stressed, and adult atopic dermatitis patients have a constellation of psychological conditions that may place them at risk for this dermatitis. Finally, it has been reported that atopic dermatitis patients have a blunted HPA response and an overactive sympathetic adrenomedullary system that may exacerbate disease.In summary, atopic dermatitis is a dermatological disorder that is characterized initially as an acute TApproximately 2% of the population in the USA is diagnosed with psoriasis . Most neH1 cells are recruited into the skin and secrete IFNγ. In turn, the IFNγ induces local antigen-presenting cells to secrete IL-1 and IL-23 that promote the expansion and survival of IL-17 expressing CD4+ and CD8+ T cells. Trafficking of IL-17 expressing CD8+ T cells into the epidermis then promotes epidermal hyperplasia [ Psoriasis is a multifactorial disease shaped by genetics and environmental factors that include psychological stress . Currenterplasia . The T-c+ T cells and monocytes in their blood as compared with a nonpsoriatic control group. On the other hand, numbers of CD3+/CD25+ T cells were decreased in psoriatics as compared with nonpsoriatic controls. Psychological stress increased the numbers of CD3+, CD8+, CD16+/CD56+ , and CD3+/HLA-DR leukocytes in the blood, although the differences between psoriatics and nonpsoriatics were insignificant [+ T cells increased significantly only in the blood of psoriatics following psychological stress. Importantly, increased T-cell counts were due to increased numbers of CD8+ and CD3+CLA+ T cells . Similarly, CLA+ NK cells were increased significantly only in the circulation of psoriatics following psychological stress. Importantly, the CLA molecule is required for the trafficking of the cells to skin. Psychological stressors have been reported to precede the onset of psoriasis in 44% of patients and to initiate recurrent skin flares in 88% of psoriatics , 104. Bunificant . Schmid-nificant . In cont Interestingly, psoriasis patients who reported stress-exacerbated flares were found to have decreased levels of cortisol and epinephrine . Thus, s Psychological stress may also enhance neurogenic inflammation in psoriatics. Harvima et al. evaluated involved and uninvolved skin from stressed and nonstressed patients through immunohistochemistry . CGRP an In summary, psoriasis is a multifactorial disease with a strong T-cell component. Psychological stress has been shown to trigger disease and exacerbate skin flares in some patients. Experimental psychological stressors have been shown to increase circulating levels of T cells, including T cells expressing the requisite proteins for skin homing . Second, the response of the HPA axis may be blunted in psoriasis patients with stress sensitivity. However, discordant results suggest that more studies are needed to determine the role of the HPA axis in psoriasis. Finally, psychological stress may enhance neurogenic inflammation in psoriatics.α treatment) and psychosis (dapsone treatment). Locala has recently reviewed skin diseases caused or exacerbated by psychotropic medications as well as psychiatric adverse effects of dermatologic medications [ Psychotropic medications  can lead to skin rash and skin allergy as well as severe skin reactions (Stevens-Johnson syndrome for treatment with anticonvulsants). On the other hand, adverse psychiatric effects to dermatological medications and treatments can include depression  psychotherapy, (2) biofeedback, (3) hypnosis, and (4) cognitive behavioral methods –113. Hypnosis is just one example of psychiatric treatment augmenting dermatological treatments for dermatoses. Shenefelt performed a MEDLINE search that covered the years 1966–1998 using search terms related to hypnosis and skin disease . Results The response to psychological stress is hypothesized to be an evolutionary adaptation for the fight-or-flight response. In contrast, for contemporary humans, activation of the HPA axis as a result of psychological stress can result in a number of undesirable physiological responses including the exacerbation of skin diseases. It has been shown that elements of the HPA axis as well as the sympathetic nervous system can modulate the innate and adaptive cutaneous immune responses, and a number of experiments have suggested that psychological stress can impact disease development and progression. Recent studies have shown that skin has its own HPA axis that may “fine tune” the response of the central HPA axis. The skin is especially sensitive to psychological stressors. Indeed, cooccurring psychiatric disorders are prevalent in patients with skin disorders. Both the innate and adaptive cutaneous immune responses are impacted by psychological stress as demonstrated in a number of experimental studies in both laboratory rodents and humans. Mouse models of contact hypersensitivity strongly suggest that the nature of the sensitizing agent, the dose of the contact sensitizing agent, and the timing of the stressor are all variables that are important for the ensuing immune response. Modulation of the cutaneous immune system by psychological stress most likely affects the course of skin diseases, including atopic dermatitis and psoriasis. Future investigations that explore the interconnections between psychological stress and the cutaneous innate and adaptive immune responses will enhance our understanding of skin immunology and immunological mediated skin diseases, provide unique insight into the mind and body connection, and may lead to new treatment programs that will improve patient care.


In human immune system, V(D)J recombination produces an enormously large repertoire of immunoglobulins (Ig) so that they can tackle different antigens from bacteria, viruses and tumor cells. Several studies have demonstrated the utility of next-generation sequencers such as Roche 454 and Illumina Genome Analyzer to characterize the repertoire of immunoglobulins. However, these techniques typically require separation of B cell population from whole blood and require a few weeks for running the sequencers, so it may not be practical to implement them in clinical settings. Recently, the Ion Torrent personal genome sequencer has emerged as a tabletop personal genome sequencer that can be operated in a time-efficient and cost-effective manner. In this study, we explored the technical feasibility to use multiplex PCR for amplifying V(D)J recombination for IgH, directly from whole blood, then sequence the amplicons by the Ion Torrent sequencer. The whole process including data generation and analysis can be completed in one day. We tested the method in a pilot study on patients with benign, atypical and malignant meningiomas. Despite the noisy data, we were able to compare the samples by their usage frequencies of the V segment, as well as their somatic hypermutation rates. In summary, our study suggested that it is technically feasible to perform clinical monitoring of V(D)J recombination within a day by personal genome sequencers. Over 25 years ago, Susumu Tonegawa won the Nobel Prize in Physiology & Medicine for discovering the genetics behind V(D)J recombination, which refers to the genomic rearrangement of variable (V), diversity (D), and joining (J) gene segments separated by highly variable junction regions Despite its importance in human disease and health, conventional methods to measure V(D)J recombination have several limitations to prevent detailed characterization of the immune repertoire. Many earlier methods, such as restriction enzyme digestion followed by Southern blotting or sizing of polymerase chain reaction (PCR) products from Ig loci, were developed as simple measures of the clonality of B cells, but they are too coarse to reveal the intra-clonal heterogeneity. Later approaches, such as multi-parameter flow cytometry, spectrotyping, or custom-designed real-time PCR assays, are more quantitative and offer higher resolution, but these methods are labor intensive and are unable to offer sequence-level insights as to the exact V(D)J recombination patterns in patients. Given the enormous amounts of information content embedded within the immune repertoire, sequence-level examination is expected to offer the most detailed characterization of V(D)J recombination in human subjects.With the development of massively parallel sequencing technologies, it is now feasible to assay V(D)J recombination by next-generation sequencing, as a means to exhaustively profile the immune repertoire in human subjects. One of the first such studies, published in late 2009, measured and clinically monitored human lymphocyte clonality by massively parallel pyrosequencing using the Roche 454 sequencers de novo assembly.Given the limitations of previous studies, our goal is to evaluate whether a new generation of personal genome sequencers can be used to interrogate V(D)J recombination within a relatively short period of time (within one day). Our study differs in several major aspects: First, instead of relying on flow cytometry or magnetic beads to isolate B cell populations from peripheral blood, we attempted to assay DNA extracted directly from whole blood. Second, we used genomic DNA rather than mRNA, as the extraction of genomic DNA from blood is technically more straightforward and genomic DNA is far less likely to be degraded under clinical storage conditions. Third, we evaluated the usage of Ion Torrent sequencer, an integrated semiconductor device that performs non-optical DNA sequencing of genomes with a turnaround time within hours To evaluate our approach, we tested it on blood samples collected from patients with meningiomas − the most common brain tumors in the United States, and compared the sequence data between patients with benign (grade I), atypical (grade II) and malignant (grade III) tumors. Meningioma arises from the membranous layers surrounding the central nervous system, thus it is not subject to blood-brain barrier. Many previous studies have already reported the presence of both humoral H region , atypical (grade II) or malignant (grade III) meningiomas, respectively. Unlike single predominant bands observed for lymphoblastoid cell line, DNA electrophoresis revealed multiple bands for both primer pools Figure 2H regions (H containing reads (11.4%) compared to atypical or benign ones  may have higher clonality in IgH populations, due to increased humoral immune responses. To test this, we performed correlation analysis to compare the V segment usage frequencies between three tumor subtypes using BWA-SW mapping result Figure 35 to 106), so that the mutation rate can reach 1 per 1,000 for each V gene base pair per cell division, further diversifying the immune repertoire beyond the genetic makeup of IgH. However, one potential confounding factor is that Ion Torrent sequencer itself may introduce sequencing errors, with observed error rate of 1.5% Given the availability of individual sequence reads, we next performed comparative analysis on somatic hypermutations between three tumor subtypes. Following activation of naïve B cells, the IgH locus experiences a highly accelerated rate of somatic mutation J recombination. However, the current turnaround time of a personal genome sequencer is still not quick enough for this approach to be considered as a point-of-care test, thus further reduction of turnaround time is necessary. In addition to evaluation of feasibility, we also made preliminary observation that IgH hypermutation rates differ between patients with different severity of the disease.There are several technical details worth noting. First of all, unlike all previous studies, our goal is not to interrogate patients with lymphoid malignancies who already have clonal expansion of B-cell populations, but to evaluate patients with meningiomas who have humoral immune responses. Therefore, besides the ability to evaluate technology, we also attempted to address an interesting question whether patients with brain tumor differ in immune responses. Due to small sample size, we cannot make a definitive conclusion. Second, to simulate the situation of B-cell clonal expansion, we have assayed a lymphoblast cell line, and confirmed the efficiency of the BIOMED-2 primer sets on samples with monoclonal expansion of B cells. We believe that this step is highly important for our selection of bands to excise in the sequencing experiments. Third, we obtained only ∼150 bp average read length from the Ion Torrent sequencer. Additionally, due to technical limitations, our sample preparation procedure includes a step to sonicate DNA fragments for the Ion Torrent run. Unfortunately, the vast majority of reads do not cover the entire V-D-J junction, complicating our analysis. With the development of sequencers that can generate longer fixed-length reads such as Illumina MiSeq  or HiSeq 2500 , this problem may be better addressed by different personal genome sequencers in the future. Fourth, the blood samples that we used were previously frozen samples rather than freshly collected blood. Since DNAs are far more stable than RNAs, our results demonstrated that frozen blood samples could yield reliable results, which may not be attainable using RNA-based procedures. Considering that DNAs are much easier to process than RNAs, we expect that DNA-based approaches will be more likely adopted in clinical settings.H segments and has smaller somatic hypermutation rates, in comparison with the atypical and malignant samples. For the former observation, although the sequenced DNA fragments may include both targeted V(D)J recombination events and contaminations , the data collected from meningioma patients with different grade tumors revealed increased portion of VH-segment reads in the total reads associated with malignancy of meningiomas. Such an increase may reflect clonal expansion in malignant tumor. For the latter observation, intuitively one would expect to see more frequent somatic hypermutations with increased severity of diseases, as a result of the immune system trying to adapt to tumor antigens. Nevertheless, we still wish to stress that our study is a pilot study and the observations are only restricted to three samples, thus any conclusion requires further validation by studies with larger sample size.One interesting observation from our study is that the benign sample shows different usage statistics of VWe expect that personal genome sequencers will increasingly find their usage in clinical monitoring of patients and help guide the selection of therapeutic regimens. The capability to generate sequence data within days greatly helps clinical applications. In our study, the use of whole blood rather than isolated B cells, the use of DNA rather than RNA, and the use of Ion Torrent sequencers are the keys to a relatively short turnaround time. Therefore, with further optimization of protocols, this approach may represent a viable option for clinical monitoring of patients with lymphoid malignancies or other types of malignancies. Finally, in the past decades, numerous biobanks with enormous collections of frozen blood have been established and served as resources to study the genetics of human diseases We collected peripheral blood from patients with meningiomas from the USC Brain Tumor Bank. All samples have extensive phenotype information, including available consistency data and brain perfusion data  to facilitate interpretation of results, especially clonality measures. The study was approved by the Institutional Review Board at the University of Southern California. Informed written consent was obtained for all participants prior to undergoing surgical tumor resection. All patients presenting to Los Angeles County – USC Medical Center or Keck Hospital of USC with benign, atypical or malignant neoplasms of the brain were eligible participants.We directly extracted genomic DNA from frozen whole blood using Qiagen blood DNA extraction kit, without isolating specific cell populations. DNA concentrations were determined by a Nanodrop spectrophotometer. To amplify V(D)J recombination in IgH locus, we followed previous studies and used the BIOMED-II primer sets We used the Ion Torrent 316 chip with the 200 bp kit for generation of sequencing data on the Ion Torrent sequencer. Briefly, we followed the manufacturer’s recommended library construction procedures, sonicated the raw PCR products into ∼250 bp fragments and then added adaptors for next-generation sequencing.Unlike genome or exome sequencing, the nature of the V(D)J sequencing data from IgH locus requires some adjustments for reads mapping, as commonly used alignment software for sequencing data requires a reference sequence that is sufficiently similar to the sequences to be tested. As global alignment tools such as BWA http://www.ncbi.nlm.nih.gov/sra) with project number PRJNA213114.The raw sequencing data in the study are available for download from Sequence Read Archive (


There is growing evidence that chronic inflammatory processes are involved in triggering the sequence from chronic liver injury to liver fibrosis, ultimately leading to liver cancer. In the last years this process has been recapitulated in a growing number of different mouse models. However, it has remained unclear whether and how these mouse models reflect the clinical reality of human hepatocellular carcinoma (HCC).Research with animal models but also human liver specimens has indicated that the NF-&κB signaling pathway might withhold a crucial function in the mediation of chronic hepatic inflammation and the transition to HCC in humans. However, previous studies led to divergent and partly conflicting results with regards to the functional role of NF-&κB in hepatocarcinogenesis. Here, we discuss a new genetic mouse model for HCC, the liver-specific TAK1 knockout mouse, which lacks the NF-&κB activating kinase TAK1 specifically in parenchymal liver cells. Molecular findings in this mouse model and their possible significance for chemopreventive strategies against HCC are compared to other murine HCC models. In mostorbidity , 4. In aOnly recently, small inhibitor molecules have entered clinical practice to treat patients suffering from HCC. As such, Sorafenib (Nexavar®) is one of the new therapeutic agents that inhibit both pro-angiogenic  and tumorigenic  receptor tyrosine kinases. Its efficacy in the context of HCC treatment was demonstrated in two large phase III clinical trials , which were conducted in both Western and Asian countries , 6. BesiHowever, these new therapeutics “only” prolong survival and are palliative, while substances that could be used in an adjuvant setting are still lacking. In addition, it has to be clearly stated that HCC represent a diverse spectrum of cancers that will likely need - depending on the tumor type and tumor stage - different therapeutic strategies. In summary, systemic therapeutic options for HCC treatment are currently limited, underlining the need for new molecular targets. As outlined above, it has been well established that chronic inflammation and fibrosis precedes hepatocarcinogenesis. The eradication of the most common cause of chronic hepatic inflammation in humans (infection with HBV and HCV) is currently unattainable. Therefore, identification of central inflammatory signaling pathways that drive the transition from chronic liver injury to dysplasia and HCC might indeed open new possibilities for HCC-chemoprevention in a setting of chronic hepatitis.in vivo. Moreover, animal models also represent a valuable tool to pre-screen various therapeutic compounds for their efficacy to inhibit particular signaling pathways and prevent or decelerate HCC development.In order to gain a better functional insight into the molecular mechanisms of hepatocarcinogenesis, multiple studies were performed using human HCC tissue. In the last years, a collection of genetic and epigenetic alterations, chromosomal aberrations, gene mutations and altered molecular pathways was described . As suchThe fact that inflammatory stimuli promote HCC development has been recapitulated in various rodent models and indeed during the last decades different models of chronic or acute liver damage induced carcinogenesis  have been established. One of the best studied chemically induced HCC-models is the diethylnitrosamine (DEN) induced liver carcinogenesis, which has been established in rats and mice . In miceIn contrast to the DEN-rodent model, the Mdr2-knockout mouse represents a prototype of a genetically modified mouse model used to identify the pathways responsible for chronic inflammation-induced liver cancer. Mdr2-knockout mice lack a biliary transporter protein denoted as multi-drug resistance gene 2 (mdr2) leading to cholestatic hepatitis and liver cancer . Tumor dThe differences between the above mentioned rodent HCC-models are reflected by distinct, activated inflammatory signaling pathways leading to inflammation and hepatocarcinogenesis. One of the most important and best-studied inflammatory signaling cascades involved is - indeed - the NF-kB pathway. NF-kB can be activated by different stimuli like tumor necrosis factor or Interleukin-1 and controls the transcription of inflammatory and anti-apoptotic genes . One impRag1-/- mice were devoid of chronic hepatitis, hepatocyte or oval-cell proliferation and failed to develop HCC.How can this contradictory role of IKKb signaling in HCC formation be reconciled? On the one hand IKKb signaling might be required for hepatocytes to respond to and survive carcinogenic stimuli and acute liver injury (e.g. DEN exposure). On the other hand, IKKb signaling might enable local chemokine expression by hepatocytes subsequently leading to chronic inflammation and HCC (e.g. like in the AlbLTab mouse model). Consistent with this hypothesis is the finding that AlbLTab x + or CD8+ T-cells expressing inflammatory cytokines  as well as cytolytic proteins (e.g. Granzyme B) might contribute to hepatocyte cell death and tissue remodeling and transformation, finally leading to HCC [Why could immune cells be essential for liver tumorigenesis? One explanation would be that CD4g to HCC . Consequg to HCC .LPC-KO and TAK1LPC-KO mice) leads to spontaneous HCC-development in mice  revealed that all liver tumors seen in NEMOLPC-KO mice displayed chromosomal amplifications in a more or less random manner (data not shown). In contrast, TAK1LPC-KO mice displayed defined chromosomal amplifications within certain hot-spot-areas on chromosomes 4, 8 and 13 [LPC-KO tumors and correlated with increased transcription of certain oncogenes located within the respective amplified chromosomal regions: Ntrk2, Net1 and Jun. These findings suggest completely different pathomechanisms of hepatocarcinogenesis between the TAK1- and NEMO-models: Although both mice show a defective NF-kB-activation in hepatocytes, only one model is associated with defined aberrations within certain chromosomal loci, upregulation of particular oncogenes as well as different histopathological features. This underlines that currently unknown molecular pathways downstream of TNF-associated molecules exist which might couple inflammation with specific genetic alterations as the basis for malignant transformation of hepatocytes. In this light, the new TAK1 model might represent an attractive model for a deeper understanding of these complex processes in the future, which might lead to a new chemopreventive strategy in patients with chronic hepatitis.HCC of TAK18 and 13 . These aGiven the rising number of genetic or chemical murine HCC models, the question remains if all these models are of significance for the understanding of human hepatocarcinogenesis and which of these models reflect which type of HCC in patients. This question could be addressed by a more systematic approach to compare specific molecular and genetic features between the different murine HCC models. As such, chromosomal aberrations in the various murine models, histopathology, transcriptional and metabolic changes could be compared at different stages of tumor initiation and promotion and correlated with the development of HCC in cirrhotic transformed livers. The same applies to signalome and transcriptome analyses or the possible role of hepatic stem cells during tumorigenesis.The absence of a curative pharmacological treatment approach for human HCC and the limitations of the present molecular inhibitors in the palliative situation clearly underline the need for the identification of novel target molecules. The unique inflammation- carcinogenesis sequence in HCC suggest that such specific inhibitors against inflammatory signaling pathways may allow to intercept the continious transition from chronic liver injury to HCC. A systematic analysis of the various available murine liver cancer models might be the basis for the future identification of these potential targets and might open the door to the successful chemoprevention against liver cancer.


The present study aimed to investigate changes in structural gray matter (GM) volume and functional amplitude of spontaneous low-frequency oscillations (LFO) and functional connectivity density in patients with subcortical vascular mild cognitive impairment (svMCI). Structural MRI and resting-sate functional MRI data were collected from 26 svMCI patients and 28 age- and gender-matched healthy controls. Structurally, widespread GM atrophy was found in the svMCI patients that resided primarily in frontal  and temporal  brain regions as well as several subcortical brain sites . Functionally, svMCI-related changes were predominantly found in the default mode network (DMN). Compared with the healthy controls, the svMCI patients exhibited decreased LFO amplitudes in the anterior part of the DMN , whereas increased LFO amplitudes in the posterior part of the DMN . As for functional connectivity density, the DMN regions  consistently exhibited decreased functional connectivity. Finally, the overall patterns of functional alterations in LFO amplitudes and functional connectivity density remained little changed after controlling for structural GM volume losses, which suggests that functional abnormalities can be only partly explained by morphological GM volume changes. Together, our results indicate that svMCI patients exhibit widespread abnormalities in both structural GM volume and functional intrinsic brain activity, which have important implications in understanding the pathophysiological mechanism of svMCI. Mild cognitive impairment (MCI) refers to a transitional state between normal aging and dementia and is characterized by various symptom clusters. As a clinically heterogeneous syndrome, MCI can be classified into subtypes of amnestic and non-amnestic phenotypes, both of which can be further subdivided into two groups that exhibit cognitive deficits in single and multiple functional domains in vivo by neuroimaging techniques, such as structural MRI (sMRI) and resting-state functional MRI (R-fMRI). Importantly, sMRI provides rich morphological information of brain tissues and has been extensively used to reveal cortical atrophy, thinning and deformation in response to pathological attacks. With respect to svMCI, Seo et al. Previous studies have shown that human brain structure and function can be explored Recently, R-fMRI has emerged as an effective, noninvasive imaging technique that is used to study the intrinsic functional architecture of the human brain when subjects are not engaged in external tasks. R-fMRI measures the spontaneous neural activity as low-frequency  oscillations (LFO) of BOLD signals that are crucial for the understanding of the intrinsic functional organization of the human brain In the current study, we performed a multimodal imaging analysis by combining sMRI and R-fMRI to explore both structural and functional brain abnormalities in patients with svMCI. Functionally, we utilized two test-retest reliable measures, the amplitude of low-frequency fluctuation (ALFF) Fifty-four right-handed participants, including 26 svMCI patients  and 28 healthy controls (HC)  participated in this study. The recruited patients were outpatients who were registered at the neurology department of Xuanwu Hospital, Capital Medical University, Beijing, China. The healthy controls were community residents from Beijing who were recruited by advertisements. The diagnosis of svMCI was performed by two experienced neurologists in consensus according to criteria 2]. Resting-state functional images were acquired using an echo-planar imaging (EPI) sequence . The subjects were instructed to lie quietly in the scanner with their eyes closed and to remain stable as much as possible during the data acquisition. The functional scan lasted for 478 s (239 volumes) in total.All images were acquired using a 3.0 T Siemens scanner at Xuanwu Hospital, Capital Medical University. During the scan, foam pads and headphones were used to reduce head motion and scanner noise as much as possible. Structural images were collected using a sagittal magnetization-prepared rapid gradient echo (MP-RAGE) three-dimensional T1-weighted sequence [repetition time (TR) = 1900 ms; echo time (TE) = 2.2 ms; inversion time (TI) = 900 ms; flip angle (FA) = 9°; number of slices = 176; slice thickness = 1.0 mm; data matrix = 256×256; field of view (FOV) = 256×256 mmhttp://www.fil.ion.ucl.ac.uk/spm). Briefly, individual structural images  were co-registered to their corresponding mean functional images  using a linear transformation To identify brain regions that showed morphological GM volume changes in the svMCI patients relative to healthy controls, we performed a VBM analysis on the structural images using the SPM8 package (http://www.fil.ion.ucl.ac.uk/spm). Before the preprocessing, the first five volumes of each subject were discarded to account for the effects of T1 equilibration and the subjects' adaptation to the circumstances, leaving 234 images for further analysis. The remaining functional images were corrected for intra-volume acquisition time delays between slices and for inter-volume geometrical displacements due to head movement. No participants were excluded according to the criteria of a displacement larger than 3 mm or an angular rotation greater than 3° in any of the x, y or z directions throughout the course of scan. There was no significant difference in the mean absolute values of head motion in any direction . Next, all functional data were normalized to the MNI space by applying transformation parameters that were obtained in the segmentation of the structural images to those time- and motion-corrected functional images. The resultant normalized functional images underwent further spatial smoothing (6-mm FWHM Gaussian kernel) and a removal of linear trends. Finally, temporal band-filtering (0.01 Hz<f<0.1 Hz) was performed to reduce the effects of low-frequency drifts and high frequency noise Data preprocessing of the functional images was also conducted using the SPM5 package (http://www.restfmri.net) ALFF was calculated using REST software  with the given voxel. Given the ambiguous interpretation of negative correlations, only positive correlations were conservatively considered in the current study.3) as determined by Monte Carlo simulations To explore within-group distributions of ALFF, one-sample one-tailed t-tests were performed for each group to determine the brain regions showing larger-than-mean ALFF . The possible effects of age, gender and education level were controlled. The statistical threshold for within-group analysis was set as P<0.01 (corrected) by combining height threshold P<0.001 for individual voxels and extent threshold P<0.01  3 for functional results and cluster size >972 mm3 for structural results), as determined by Monte Carlo simulations To determine between-group differences in GM volume, ALFF and functional connectivity density, multiple linear regression analyses were performed in a voxel-wise manner  with age, gender and education as common unconcerned covariates. Specifically, total intracranial volume  was added as extra covariate for GM volume between-group comparison and maximum and root mean squares of head motion (translation and rotation) for ALFF and functional connectivity density between-group comparisons. Furthermore, to determine the contribution of structural changes on functional abnormalities, between-group comparisons of ALFF and functional connectivity density were also performed, with structural GM volume serving as another extra-explanatory variable. This specific statistical analysis was performed using the REST software  with the cognitive performance of the patients (MMSE and AVLT), we performed multiple linear regression analyses that were restricted within the brain regions that showed significant between-group differences. Age, gender and education were also treated as unconcerned covariates in the model.−6), the AVLT-immediate recall (P<10−5), the AVLT-delayed recall (P<10−6) and the AVLT-recognition (P<10−3) in comparison with the healthy controls.As shown in The svMCI patients exhibited decreased GM volume not only in cortical  but alsoCompared with the HC, the svMCI patients showed significantly decreased ALFF predominantly in the anterior part of the DMN . The svMCI patients also showed increased ALFF in regions that primarily encompassed the posterior part of the DMN  . In addiCompared with the HC, the svMCI patients showed significantly decreased functional connectivity density mainly in the DMN regions, including the PCC/PCu, MPFC, SFG and inferior parietal lobule (IPL) and HIP . The infNo significant correlations were found for structural GM volume, functional LFO amplitude and functional connectivity density with any of the clinical variables, which included MMSE, AVLT-immediate recall, AVLT-delayed recall or AVLT-recognition in the svMCI patients.In the present study, we investigated svMCI-related alterations in both functional spontaneous LFO and the structural GM volume by combining resting-state fMRI and structural MRI techniques. We found that compared with HC, the svMCI patients exhibited a functional decrease in the amplitude of spontaneous LFO, primarily in the anterior part of the DMN, whereas the amplitude was increased in the posterior part of the DMN. We also found decreased functional connectivity density in both anterior and posterior part of the DMN in svMCI patients. Structural GM atrophy was distributed over brain sites, predominantly the frontal lobe, the temporal lobe and the subcortex. These findings provide new insights into the neurophysiological alterations of the brain that are induced by svMCI.We found that the svMCI patients exhibited decreased spontaneous LFO in the MPFC, which belongs to the DMN. The DMN is a set of brain regions that routinely exhibit activity decreases during attention-demanding cognitive tasks but are the most metabolically active at rest We also found several brain regions that showed increased spontaneous LFO in the svMCI patients, such as the PCC/PCu, THA and HIP. PCC/PCu are spatially located in the posterior part of the DMN. The PCC/PCu are the most metabolically active regions in healthy subjects at rest and play key roles in default mode processing In the current study, we found that svMCI patients exhibited decreased spontaneous LFO in the anterior part of the DMN, whereas increased spontaneous LFO were found in the posterior part compared with HC. Using R-fMRI, Sun et al. We found widespread cortical GM volume loss in the svMCI patients that was predominantly distributed in frontal , temporal , occipital  and parietal  regions. The pattern of GM atrophy that was detected here was highly consistent with GM thinning in svMCI patients that has been reported in previous studies We found that large areas of the frontal lobe exhibited GM atrophy in the svMCI patients, which is consistent with a previous report of frontal cortical thinning Several temporal structures  also exhibited GM atrophy in the svMCI patients. Previous studies have demonstrated that the STG and the ITG show cortical thinning in patients with SVaD or svMCI In addition to frontal and temporal regions, the MOG and the IPL also showed GM volume loss in the svMCI patients. Occipital GM thinning has been previously reported in patients with SVaD and svMCI This investigation raised several issues that need to be addressed. First, the current study was cross–sectional; therefore, the longitudinal changes during the progression of the disease cannot be revealed by the data acquired here. Future follow-up studies can produce more fruitful insights into the svMCI. Second, svMCI patients exhibit different progressive trajectories, wherein some patients ultimately develop SVaD and others do not. Accordingly, full depictions of distinct patterns of brain abnormalities among different svMCI subtypes are warranted to elucidate the underlying neurophysiological mechanism that contributes to these disparate progressive trajectories and to provide unique characteristics for their identification and diagnosis.