Stimulus features coded by single neurons of a macaque body category selective patch

Body category-selective regions of the primate temporal cortex respond to images of bodies, but it is unclear which fragments of such images drive single neurons’ responses in these regions. Here we applied the Bubbles technique to the responses of single macaque middle superior temporal sulcus (midSTS) body patch neurons to reveal the image fragments the neurons respond to. We found that local image fragments such as extremities (limbs), curved boundaries, and parts of the torso drove the large majority of neurons. Bubbles revealed the whole body in only a few neurons. Neurons coded the features in a manner that was tolerant to translation and scale changes. Most image fragments were excitatory but for a few neurons both inhibitory and excitatory fragments (opponent coding) were present in the same image. The fragments we reveal here in the body patch with Bubbles differ from those suggested in previous studies of face-selective neurons in face patches. Together, our data indicate that the majority of body patch neurons respond to local image fragments that occur frequently, but not exclusively, in bodies, with a coding that is tolerant to translation and scale. Overall, the data suggest that the body category selectivity of the midSTS body patch depends more on the feature statistics of bodies (e.g., extensions occur more frequently in bodies) than on semantics (bodies as an abstract category).The body category-selective regions in the human occipito-temporal cortex are defined as those that respond to images of bodies (1–8). We previously identified two bilateral regions in the macaque inferotemporal cortex that respond stronger to monkey, human, and animal bodies in comparison with other stimuli, including faces (6). Subsequent single-unit recordings in the posterior body patch [i.e., the middle superior temporal sulcus (midSTS) body patch] demonstrated that indeed the average spiking activity of the neuron population was greater to images of bodies compared with other objects. However, the responses of single neurons showed a strong selectivity for particular body—and sometimes nonbody—images (7). However, it is still unknown what particular stimulus features single body patch neurons respond to. Moreover, we still do not know how those neurons code information about different animate and inanimate stimuli.The Bubbles technique (9), in which parts of the image of an object are sampled by trial-unique randomly positioned Gaussian apertures, has been used successfully in many psychophysical studies to reveal the features critical for certain perceptual tasks such as face identification, gender discrimination, emotional discrimination, and so forth (e.g., refs. 9–13). Although this technique has been used in neuroimaging [functional MRI (fMRI), EEG, magnetoencephalography (MEG), and electrocorticography] studies (11, 12, 14), it has rarely been exploited in single-unit studies (15, 16), and this only for face stimuli.Here, we used the Bubbles technique to reveal the image fragments that drive single midSTS body patch neurons. Bubbles provides an unbiased method for sampling the images with the advantage that it requires no prior specification of stimulus features to which the neurons are supposed to be selective. With fMRI, we first defined the midSTS body patch in two monkeys. Then, in this identified body patch we recorded the spiking activity of well-isolated single neurons in response to 100 images of various categories. Based on the spiking activity to the 100 images, we selected for each neuron a response-eliciting image. Then, we sampled the selected image at five different spatial scales with randomly positioned Gaussian apertures and recorded the responses of the neuron to a large number of these trial-unique Bubbles stimuli. Following the experiment, we applied reverse correlation to relate the excitatory and inhibitory neural responses to particular image fragments.Furthermore, we assessed whether the revealed image fragments tolerated changes in spatial location and size of the Bubbles stimuli or instead reflected spatially localized image regions. We showed before that many midSTS body patch neurons respond to silhouettes of bodies (17). Silhouettes isolate shape contours, removing texture and shading information. Thus, in a subset of neurons, we applied Bubbles to a silhouette version of the selected image.     

Gastric perception thresholds are low and sensory neuropeptide levels high in helicobacter pylori-positive functional dyspepsia

BACKGROUND AND AIMS: In functional dyspepsia (FD) decreased perception levels can be shown on gastric distension. Substance P (SP) and calcitonin gene-related peptide (CGRP) are involved in the sensitization of afferent neuronal pathways due to chronic inflammation. The role of Helicobacter pylori-induced gastric mucosal inflammation in the pathogenesis of FD is controversial. The aim of this study was to assess whether FD patients have altered mucosal concentrations of CGRP and SP, and to investigate whether this is associated with visceral hypersensitivity or H. pylori infection. METHODS: Gastrointestinal symptoms, H. pylori status, perception thresholds at gastric balloon distension, and gastric mucosal concentrations of CGRP and SP were determined in 13 FD patients and 18 healthy controls (HC). RESULTS: In H. pylori-positive FD patients discomfort and pain thresholds on gastric distension were lower compared to other groups. Antral mucosal levels of CGRP and SP were higher in H. pylori-positive subjects. In FD significantly negative correlations between discomfort and pain thresholds and antral mucosal concentrations of CGRP and SP were observed. CONCLUSIONS: In FD low perception thresholds on gastric distension are associated with high levels of CGRP and SP in the antrum, suggesting that sensory neuropeptides are involved in FD pathophysiology.     

Zoonotic Dirofilaria repens (Nematoda: Filarioidea) in Aedes vexans mosquitoes,Czech Republic

The surveillance of vectors for arthropod-borne pathogens is nowadays an important tool in surveillance programmes throughout Europe. Whereas many studies have been performed to screen arthropods for viruses or bacterial pathogens, only limited information is available concerning the geographical distribution and vector range of pathogenic filariae in Central Europe. To consider the prevalence of filarial parasites in mosquito vectors, we performed a molecular survey of mosquitoes for filarial DNA. Mosquito collection was conducted at six study sites in the South Moravian region (Czech Republic) close to the borders with Slovakia and Austria from 2009 to 2011. Molecular screening of mosquitoes was conducted using conventional PCR with primers designed to amplify the mitochondrial cytochromoxidase subunit I gene as well as the partial 5.8S ribosomal RNA gene. A total of 13,222 mosquitoes belonging to six species were captured and distributed into 237 pools with different numbers of individuals. Overall, four pools were positive for Dirofilaria repens (a minimum infection rate 0.03 %) at two study sites (both natural and urban). Another filarial parasite detected during a study into Aedes vexans mosquitoes revealed the closest homology to Setaria spp. We detected specific D. repens DNA in Ae. vexans mosquitoes for the first time in the Czech Republic and confirmed the circulation of Dirofilaria spp. in a natural focus of infection providing an epidemiological link between autochthonous canine cases and mosquito vectors in the area studied.     

Chemokines and Antimicrobial Peptides Have a cag-Dependent Early Response to Helicobacter pylori Infection in Primary Human Gastric Epithelial Cells

Helicobacter pylori infection systematically causes chronic gastric inflammation that can persist asymptomatically or evolve toward more severe gastroduodenal pathologies, such as ulcer, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. The cag pathogenicity island (cag PAI) of H. pylori allows translocation of the virulence protein CagA and fragments of peptidoglycan into host cells, thereby inducing production of chemokines, cytokines, and antimicrobial peptides. In order to characterize the inflammatory response to H. pylori, a new experimental protocol for isolating and culturing primary human gastric epithelial cells was established using pieces of stomach from patients who had undergone sleeve gastrectomy. Isolated cells expressed markers indicating that they were mucin-secreting epithelial cells. Challenge of primary epithelial cells with H. pylori B128 underscored early dose-dependent induction of expression of mRNAs of the inflammatory mediators CXCL1 to -3, CXCL5, CXCL8, CCL20, BD2, and tumor necrosis factor alpha (TNF-α). In AGS cells, significant expression of only CXCL5 and CXCL8 was observed following infection, suggesting that these cells were less reactive than primary epithelial cells. Infection of both cellular models with H. pylori B128ΔcagM, a cag PAI mutant, resulted in weak inflammatory-mediator mRNA induction. At 24 h after infection of primary epithelial cells with H. pylori, inflammatory-mediator production was largely due to cag PAI substrate-independent virulence factors. Thus, H. pylori cag PAI substrate appears to be involved in eliciting an epithelial response during the early phases of infection. Afterwards, other virulence factors of the bacterium take over in development of the inflammatory response. Using a relevant cellular model, this study provides new information on the modulation of inflammation during H. pylori infection.     

Parameter Study on the Preparation of UV Depth‐Cured Chemically Resistant Polysulfone‐Based Membranes

Polysulfone‐based membranes with excellent chemical resistance and a wet thickness up to 200 μm are obtained via UV curing of unmodified polymers after careful tuning of the photoinitiating system and the crosslinker structure. Combinations of photoinitiator and crosslinker are studied in depth, followed by a characterization of the formed macromolecular structure. The performance of the resulting membranes is then evaluated through long‐term immersion in solvents. Classical depth‐curing acyl phosphine oxide‐based photoinitiators in combination with a pentaacrylate crosslinker are found to be the optimal system.

     

A Comparison of Radiation Dose Between Standard and 3D Angiography in Congenital Heart Disease

Background

The use of three-dimensional rotational angiography (3D-RA) to assess patients with congenital heart diseases appears to be a promising technique despite the scarce literature available.

Objectives

The objective of this study was to describe our initial experience with 3D-RA and to compare its radiation dose to that of standard two-dimensional angiography (2D-SA).

Methods

Between September 2011 and April 2012, 18 patients underwent simultaneous 3D-RA and 2D-SA during diagnostic cardiac catheterization. Radiation dose was assessed using the dose-area-product (DAP).

Results

The median patient age and weight were 12.5 years and 47.5 Kg, respectively. The median DAP of each 3D-RA acquisition was 1093µGy.m² and 190µGy.m² for each 2D-SA acquisition (p<0.01). In patients weighing more than 45Kg (n=7), this difference was attenuated but still significant (1525 µGy.m² vs.413µGy.m², p=0.01). No difference was found between one 3D-RA and three 2D-SA (1525µGy.m² vs.1238 µGy.m², p = 0.575) in this population. This difference was significantly higher in patients weighing less than 45Kg (n=9) (713µGy.m² vs.81µGy.m², P = 0.008), even when comparing one 3D-RA with three 2D-SA (242µGy.m², respectively, p<0.008). 3D-RA was extremely useful for the assessment of conduits of univentricular hearts, tortuous branches of the pulmonary artery, and aorta relative to 2D-SA acquisitions.

Conclusions

The radiation dose of 3D-RA used in our institution was higher than those previously reported in the literature and this difference was more evident in children. This type of assessment is of paramount importance when starting to perform 3D-RA.     

Diagnosis and mortality prediction in pulmonary hypertension: the value of the electrocardiogram-derived ventricular gradient

PurposeThe aim of this study was to investigate the use of the electrocardiogram-derived ventricular gradient, projected on the x-axis (VGx), for detection of pulmonary hypertension (PH) and for prediction of all-cause mortality in PH patients.MethodsIn patients referred for PH screening (n = 216), the VGx was calculated semiautomatically from the electrocardiogram and was defined as abnormal when less than 24 mV·ms. The VGx of PH patients was compared with the VGx of patients without PH. The association between a reduced VGx and mortality was investigated in PH patients.ResultsPatients with PH (n = 117) had a significantly reduced VGx: 14 ± 27 vs 45 ± 23 mV·ms, P < .001. Furthermore, a severely reduced VGx (<0 mV·ms) was associated with increased mortality in PH patients: hazard ratio, 1.025 (95% confidence interval, 1.006-1.045; P = .012) per mV·ms VGx decrease.ConclusionReduced VGx is associated with the presence of PH and, more importantly, within PH patients, a severely reduced VGx predicts mortality.