Long-range phase synchronization of high-gamma activity in human cortex

AbstractInter-areal synchronization of neuronal oscillations below 100 Hz is ubiquitous in cortical circuitry and thought to regulate neuronal communication. In contrast, faster activities are generally considered to be exclusively local-circuit phenomena. We show with human intracerebral recordings that 100–300 Hz high-gamma activity (HGA) may be synchronized between widely distributed regions. HGA synchronization was not attributable to artefacts or to epileptic pathophysiology. Instead, HGA synchronization exhibited a reliable cortical connectivity and community structures, and a laminar profile opposite to that of lower frequencies. Importantly, HGA synchronization among functional brain systems during non-REM sleep was distinct from that in resting state. Moreover, HGA synchronization was transiently enhanced for correctly inhibited responses in a Go/NoGo task. These findings show that HGA synchronization constitutes a new, functionally significant form of neuronal spike-timing relationships in brain activity. We suggest that HGA synchronization reflects the temporal microstructure of spiking-based neuronal communication per se in cortical circuits

Comparative genome analysis of Lactobacillus casei strains isolated from Actimel and Yakult products reveals marked similarities and points to a common origin

Corrigendum: Douillard, F. P., Kant, R., Ritari, J., Paulin, L., Palva, A. & de Vos, W. M. Microbial Biotechnology 2014, 7, 1, p. 85, DOI: 10.1111/1751-7915.12095Peer reviewe

Whole-brain computation of cognitive versus acoustic errors in music : A mismatch negativity study

Previous studies have evidenced how the local prediction of physical stimulus features may affect the neural processing of incoming stimuli. Less known are the effects of cognitive priors on predictive processes, and how the brain computes local versus cognitive predictions and their errors. Here, we determined the differential brain mechanisms underlying prediction errors related to high-level, cognitive priors for melody (rhythm, contour) versus low-level, local acoustic priors (tuning, timbre). We measured with magnetoencephalography the mismatch negativity (MMN) prediction error signal in 104 adults having varying levels of musical expertise. We discovered that the brain regions involved in early predictive processes for local priors were primary and secondary auditory cortex and insula, whereas cognitive brain regions such as cingulate and orbitofrontal cortices were recruited for early melodic errors in cognitive priors. The involvement of higher-level brain regions for computing early cognitive errors was enhanced in musicians, especially in cingulate cortex, inferior frontal gyrus, and supplementary motor area. Overall, the findings expand knowledge on whole-brain mechanisms of predictive processing and the related MMN generators, previously mainly confined to the auditory cortex, to a frontal network that strictly depends on the type of priors that are to be computed by the brain.Peer reviewe

Characterization of Highly Mucus-Adherent Non-GMO Derivatives of Lacticaseibacillus rhamnosus GG

Lacticaseibacillus rhamnosusGG is one of the best studied lactic acid bacteria in the context of probiotic effects.L. rhamnosusGG has been shown to prevent diarrhea in children and adults and has been implicated to have mitigating or preventive effects in several disorders connected to microbiota dysbiosis. The probiotic effects are largely attributed to its adhesive heterotrimeric sortase-dependent pili, encoded by thespaCBA-srtC1gene cluster. Indeed, the strain-specific SpaCBA pili have been shown to contribute to adherence, biofilm formation and host signaling. In this work we set out to generate non-GMO derivatives ofL. rhamnosusGG that adhere stronger to mucus compared to the wild-type strain using chemical mutagenesis. We selected 13 derivatives that showed an increased mucus-adherent phenotype. Deep shotgun resequencing of the strains enabled division of the strains into three classes, two of which revealed SNPs (single nucleotide polymorphisms) in thespaAandspaCgenes encoding the shaft and tip adhesive pilins, respectively. Strikingly, the other class derivatives demonstrated less clear genotype - phenotype relationships, illustrating that pili biogenesis and structure is also affected by other processes. Further characterization of the different classes of derivatives was performed by PacBio SMRT sequencing and RNAseq analysis, which resulted in the identification of molecular candidates driving pilin biosynthesis and functionality. In conclusion, we report on the generation and characterization of three classes of strongly adherentL. rhamnosusGG derivatives that show an increase in adhesion to mucus. These are of special interest as they provide a window on processes and genes driving piliation and its control inL. rhamnosusGG and offer a variety of non-GMO derivatives of this key probiotic strain that are applicable in food products.Peer reviewe

Molecular ecology of the yet uncultured bacterial Ct85-cluster in the mammalian gut

In our previous studies on irritable bowel syndrome (IBS) –associated microbiota by molecular methods, we demonstrated that a particular 16S rRNA gene amplicon was more abundant in the feces of healthy subjects or mixed type IBS (IBS-M) –sufferers than in the feces of individuals with diarrhea-type IBS (IBS-D). In the current study, we demonstrated that this, so called Ct85-amplicon, consists of a cluster of very heterogeneous 16S rRNA gene sequences, and defined six 16S rRNA gene types, a to f, within this cluster, each representing a novel species-, genus- or family level taxon. We then designed specific PCR primers for these sequence types, mapped the distribution of the Ct85-cluster sequences and that of the newly defined sequence types in several animal species and compared the sequence types present in the feces of healthy individuals and IBS sufferers using two IBS study cohorts, Finnish and Dutch. Various Ct85-cluster sequence types were detected in the fecal samples of several companion and production animal species with remarkably differing prevalences and abundances. The Ct85 sequence type composition of swine closely resembled that of humans. One of the five types (d) shared between humans and swine was not present in any other animals tested, while one sequence type (b) was found only in human samples. In both IBS study cohorts, one type (e) was more prevalent in healthy individuals than in the IBS-M group. By revealing various sequence types in the widespread Ct85-cluster and their distribution, the results improve our understanding of these uncultured bacteria, which is essential for future efforts to cultivate representatives of the Ct85-cluster and reveal their roles in IBS.Peer reviewe

Using recombinant lactococci as an approach to dissect the immunomodulating capacity of surface piliation in probiotic Lactobacillus rhamnosus GG

Peer reviewe

Using recombinant lactococci as an approach to dissect the immunomodulating capacity of surface piliation in probiotic Lactobacillus rhamnosus GG

Peer reviewe

Obliteration of radical cavities with autogenous cortical bone; long-term results

<p>Abstract</p> <p>Background</p> <p>To evaluate the long-term surgical outcome(s) in patients who have undergone canal-wall-down operation with mastoid and epitympanic obliteration using autologous cortical bone chips, bone pate and meatally-based musculoperiosteal flap technique.</p> <p>Method</p> <p>Retrospective evaluation of seventy patients operated during 1986–1991 due to a cholesteatoma. An otomicroscopy was performed to evaluate the postoperative outer ear canal configuration with a modified Likert scale (1 – 4). The outer ear canal physical volume was assessed by tympanometry. The hearing outcome and a patient-filled questionnaire were also analyzed.</p> <p>Results</p> <p>The posterior wall results were 1.8 (± 0.9 SD) and the attic region 1.8 (± 0.9 SD) (ns., p > 0.05). These values show either no cavity formation or minor formation of a cavity, with a good functional result. The mean volume of the operated ear canal was 1.7 (± 0.5 SD) ml. The volume of the contralateral ear canal was 1.2 (± 0.3 SD) ml (*** p < 0.0001). A comparison of the current mean ABG to the preoperative mean ABG and to the ABG at one-year postoperatively, 5-years postoperatively or 10-years postoperatively showed no statistical significance (p > 0.05).</p> <p>Conclusion</p> <p>ABG does not significantly change in the long-term. The configuration of the cavity tends to change, however, the obliteration material is stable in the long-term and clinically significant cavitation rarely occurs.</p

The N-Terminal GYPSY Motif Is Required for Pilin-Specific Sortase SrtC1 Functionality in Lactobacillus rhamnosus Strain GG

Predominantly identified in pathogenic Gram-positive bacteria, sortase-dependent pili are also found in commensal species, such as the probiotic-marketed strain Lactobacillus rhamnosus strain GG. Pili are typically associated with host colonization, immune signalling and biofilm formation. Comparative analysis of the N-terminal domains of pilin-specific sortases from various piliated Gram-positive bacteria identified a conserved motif, called GYPSY, within the signal sequence. We investigated the function and role of the GYPSY residues by directed mutagenesis in homologous (rod-shaped) and heterologous (coccoid-shaped) expression systems for pilus formation. Substitutions of some of the GYPSY residues, and more specifically the proline residue, were found to have a direct impact on the degree of piliation of Lb. rhamnosus GG. The present findings uncover a new signalling element involved in the functionality of pilin-specific sortases controlling the pilus biogenesis of Lb. rhamnosus GG and related piliated Gram-positive species.Peer reviewe

Manual and automatic image analysis segmentation methods for blood flow studies in microchannels

In blood flow studies, image analysis plays an extremely important role to examine raw data obtained by high-speed video microscopy systems. This work shows different ways to process the images which contain various blood phenomena happening in microfluidic devices and in microcirculation. For this purpose, the current methods used for tracking red blood cells (RBCs) flowing through a glass capillary and techniques to measure the cell-free layer thickness in different kinds of microchannels will be presented. Most of the past blood flow experimental data have been collected and analyzed by means of manual methods, that can be extremely reliable, but they are highly time-consuming, user-intensive, repetitive, and the results can be subjective to user-induced errors. For this reason, it is crucial to develop image analysis methods able to obtain the data automatically. Concerning automatic image analysis methods for individual RBCs tracking and to measure the well known microfluidic phenomena cell-free layer, two developed methods are presented and discussed in order to demonstrate their feasibility to obtain accurate data acquisition in such studies. Additionally, a comparison analysis between manual and automatic methods was performed.This project has been funded by Portuguese national funds of FCT/MCTES (PIDDAC) through the base funding from the following research units: UIDB/00532/2020 (Transport Phenomena Research Center—CEFT), UIDB/04077/2020 (Mechanical Engineering and Resource Sustainability Center—MEtRICs), UIDB/00690/2020 (CIMO). The authors are also grateful for the partial funding of FCT through the projects, NORTE-01-0145-FEDER-029394 (PTDC/EMD-EMD/29394/2017) and NORTE-01-0145-FEDER-030171 (PTDC/EMD-EMD/30171/2017) funded by COMPETE2020, NORTE2020, PORTUGAL2020 and FEDER. D. Bento acknowledges the PhD scholarship SFRH/BD/ 91192/2012 granted by FCT