Reduced neurosteroid potentiation of GABAA receptors in epilepsy and depolarized hippocampal neurons

OBJECTIVE: Neurosteroids regulate neuronal excitability by potentiating γ-aminobutyric acid type-A receptors (GABARs). In animal models of temporal lobe epilepsy, the neurosteroid sensitivity of GABARs is diminished and GABAR subunit composition is altered. We tested whether similar changes occur in patients with epilepsy and if depolarization-induced increases in neuronal activity can replicate this effect. METHODS: We determined GABAR α4 subunit expression in cortical tissue resected from pediatric epilepsy patients. Modulation of human GABARs by allopregnanolone and Ro15-4513 was measured in Xenopus oocytes using whole-cell patch clamp. To extend the findings obtained using tissue from epilepsy patients, we evaluated GABAR expression and modulation by allopregnanolone and Ro15-4513 in cultured rat hippocampal neurons exposed to high extracellular potassium (HK) to increase neuronal activity. RESULTS: Expression of α4 subunits was increased in pediatric cortical epilepsy specimens encompassing multiple pathologies. The potentiation of GABA-evoked currents by the neurosteroid allopregnanolone was decreased in Xenopus oocytes expressing GABARs isolated from epilepsy patients. Furthermore, receptors isolated from epilepsy but not control tissue were sensitive to potentiation by Ro15-4513, indicating higher expression of α INTERPRETATION: These findings suggest that seizure activity-induced upregulation of

A computational vector-map model of neonate saccades: Modulating the externality effect through refraction periods

AbstractThe present study develops an explicit and predictive computational model of neonate saccades based on the interaction of several simple mechanisms, including the tendency to fixate towards areas of high contrast, and the decay and recovery of a world-centered contrast representation simulating a low-level inhibition of return mechanism. Emergent properties similar to early visual behaviors develop, including the externality effect (or tendency to focus on external then internal features). The age-associated progression of this effect is modulated by the decay period of the model’s contrast representation, where the high-level behavior of either scanning broadly or locally is modulated by a single decay parameter

Genetic variation in the farnesoid X-receptor predicts Crohn’s disease severity in female patients

The farnesoid X receptor (FXR) is implicated in Crohn\u27s disease (CD) pathogenesis. It is unclear how genetic variation in FXR impacts CD severity versus genetic variation in nuclear receptors such as pregnane X receptor (PXR) and the multi-drug resistance protein 1 (MDR1, ABCB1). To evaluate FXR-1G \u3e T as a genomic biomarker of severity in CD and propose a plausible molecular mechanism. A retrospective study (n = 542) was conducted in a Canadian cohort of CD patients. Genotypic analysis (FXR-1G \u3e T, MDR1 3435C \u3e T and PXR -25385C \u3e T) as well as determination of the FXR downstream product, fibroblast growth factor (FGF) 19 was performed. Primary outcomes included risk and time to first CD-related surgery. The effect of estrogen on wild type and variant FXR activity was assessed in HepG2 cells. The FXR-1GT genotype was associated with the risk of (odds ratio, OR = 3.34, 95% CI = 1.58–7.05, p = 0.002) and earlier progression to surgery (hazard ratio, HR = 3.00, 95% CI = 1.86–4.83, p \u3c 0.0001) in CD. Female carriers of the FXR-1GT genotype had the greatest risk of surgery (OR = 14.87 95% CI = 4.22–52.38, p \u3c 0.0001) and early progression to surgery (HR = 6.28, 95% CI = 3.62–10.90, p \u3c 0.0001). Women carriers of FXR-1GT polymorphism had a three-fold lower FGF19 plasma concentration versus women with FXR-1GG genotype (p \u3c 0.0001). In HepG2 cells cotransfected with estrogen receptor (ER) and FXR, presence of estradiol further attenuated variant FXR activity. MDR1 and PXR genotypes were not associated with surgical risk. Unlike MDR1 and PXR, FXR-1GT genetic variation is associated with earlier and more frequent surgery in women with CD. This may be through ER-mediated attenuation of FXR activation

The composition and metabolic potential of the human small intestinal microbiota within the context of inflammatory bowel disease

BACKGROUND AND AIMS: The human gastrointestinal tract harbours distinct microbial communities essential for health. Little is known about small intestinal communities, despite the small intestine playing a fundamental role in nutrient absorption and host-microbe immune homeostasis. We aimed to explore the small intestine microbial composition and metabolic potential, in the context of inflammatory bowel disease (IBD). METHODS: Metagenomes derived from faecal samples and extensive phenotypes were collected from 57 individuals with an ileostomy or ileoanal pouch, and compared with 1178 general population and 478 IBD faecal metagenomes. Microbiome features were identified using MetaPhAn2 and HUMAnN2, and association analyses were performed using multivariate linear regression. RESULTS: Small intestinal samples had a significantly lower bacterial diversity, compared with the general population and, to a lesser extent, IBD samples. Comparing bacterial composition, small intestinal samples clustered furthest from general population samples and closest to IBD samples with intestinal resections. Veillonella atypica, Streptococcus salivarius and Actinomyces graevenitzii were among the species significantly enriched in the small intestine. Predicted metabolic pathways in the small intestine are predominantly involved in simple carbohydrate and energy metabolism, but also suggest a higher proinflammatory potential. CONCLUSION: We described the bacterial composition and metabolic potential of the small intestinal microbiota. The colonic microbiome of IBD patients, particularly with intestinal resections, showed resemblance to that of the small intestine. Moreover, several features characterising the small intestinal microbiome have been previously associated with IBD. These results highlight the importance of studying the small intestinal microbiota to gain new insight into disease pathogenesis

UV-A radiation effects on higher plants: exploring the known unknown

Ultraviolet-A radiation (UV-A: 315–400 nm) is a component of solar radiation that exerts a wide range of physiological responses in plants. Currently, field attenuation experiments are the most reliable source of information on the effects of UV-A. Common plant responses to UV-A include both inhibitory and stimulatory effects on biomass accumulation and morphology. UV-A effects on biomass accumulation can differ from those on root: shoot ratio, and distinct responses are described for different leaf tissues. Inhibitory and enhancing effects of UV-A on photosynthesis are also analysed, as well as activation of photoprotective responses, including UV-absorbing pigments. UV-A-induced leaf flavonoids are highly compound-specific and species-dependent. Many of the effects on growth and development exerted by UV-A are distinct to those triggered by UV-B and vary considerably in terms of the direction the response takes. Such differences may reflect diverse UV-perception mechanisms with multiple photoreceptors operating in the UV-A range and/or variations in the experimental approaches used. This review highlights a role that various photoreceptors (UVR8, phototropins, phytochromes and cryptochromes) may play in plant responses to UV-A when dose, wavelength and other conditions are taken into account

How does reviewing the evidence change veterinary surgeons' beliefs regarding the treatment of ovine footrot? A quantitative and qualitative study

Footrot is a widespread, infectious cause of lameness in sheep, with major economic and welfare costs. The aims of this research were: (i) to quantify how veterinary surgeons’ beliefs regarding the efficacy of two treatments for footrot changed following a review of the evidence (ii) to obtain a consensus opinion following group discussions (iii) to capture complementary qualitative data to place their beliefs within a broader clinical context. Grounded in a Bayesian statistical framework, probabilistic elicitation (roulette method) was used to quantify the beliefs of eleven veterinary surgeons during two one-day workshops. There was considerable heterogeneity in veterinary surgeons’ beliefs before they listened to a review of the evidence. After hearing the evidence, seven participants quantifiably changed their beliefs. In particular, two participants who initially believed that foot trimming with topical oxytetracycline was the better treatment, changed to entirely favour systemic and topical oxytetracycline instead. The results suggest that a substantial amount of the variation in beliefs related to differences in veterinary surgeons’ knowledge of the evidence. Although considerable differences in opinion still remained after the evidence review, with several participants having non-overlapping 95% credible intervals, both groups did achieve a consensus opinion. Two key findings from the qualitative data were: (i) veterinary surgeons believed that farmers are unlikely to actively seek advice on lameness, suggesting a proactive veterinary approach is required (ii) more attention could be given to improving the way in which veterinary advice is delivered to farmers. In summary this study has: (i) demonstrated a practical method for probabilistically quantifying how veterinary surgeons’ beliefs change (ii) revealed that the evidence that currently exists is capable of changing veterinary opinion (iii) suggested that improved transfer of research knowledge into veterinary practice is needed (iv) identified some potential obstacles to the implementation of veterinary advice by farmers

Faecal metabolome and its determinants in inflammatory bowel disease

OBJECTIVE: Inflammatory bowel disease (IBD) is a multifactorial immune-mediated inflammatory disease of the intestine, comprising Crohn's disease and ulcerative colitis. By characterising metabolites in faeces, combined with faecal metagenomics, host genetics and clinical characteristics, we aimed to unravel metabolic alterations in IBD.DESIGN: We measured 1684 different faecal metabolites and 8 short-chain and branched-chain fatty acids in stool samples of 424 patients with IBD and 255 non-IBD controls. Regression analyses were used to compare concentrations of metabolites between cases and controls and determine the relationship between metabolites and each participant's lifestyle, clinical characteristics and gut microbiota composition. Moreover, genome-wide association analysis was conducted on faecal metabolite levels.RESULTS: We identified over 300 molecules that were differentially abundant in the faeces of patients with IBD. The ratio between a sphingolipid and L-urobilin could discriminate between IBD and non-IBD samples (AUC=0.85). We found changes in the bile acid pool in patients with dysbiotic microbial communities and a strong association between faecal metabolome and gut microbiota. For example, the abundance of Ruminococcus gnavus was positively associated with tryptamine levels. In addition, we found 158 associations between metabolites and dietary patterns, and polymorphisms near NAT2 strongly associated with coffee metabolism.CONCLUSION: In this large-scale analysis, we identified alterations in the metabolome of patients with IBD that are independent of commonly overlooked confounders such as diet and surgical history. Considering the influence of the microbiome on faecal metabolites, our results pave the way for future interventions targeting intestinal inflammation.</p

De Novo Mutations in SIK1 Cause a Spectrum of Developmental Epilepsies

Developmental epilepsies are age-dependent seizure disorders for which genetic causes have been increasingly identified. Here we report six unrelated individuals with mutations in salt-inducible kinase 1 (SIK1) in a series of 101 persons with early myoclonic encephalopathy, Ohtahara syndrome, and infantile spasms. Individuals with SIK1 mutations had short survival in cases with neonatal epilepsy onset, and an autism plus developmental syndrome after infantile spasms in others. All six mutations occurred outside the kinase domain of SIK1 and each of the mutants displayed autophosphorylation and kinase activity toward HDAC5. Three mutations generated truncated forms of SIK1 that were resistant to degradation and also showed changes in sub-cellular localization compared to wild-type SIK1. We also report the human neuropathologic examination of SIK1-related developmental epilepsy, with normal neuronal morphology and lamination but abnormal SIK1 protein cellular localization. Therefore, these results expand the genetic etiologies of developmental epilepsies by demonstrating SIK1 mutations as a cause of severe developmental epilepsy

Consensus classification of human prion disease histotypes allows reliable identification of molecular subtypes: an inter-rater study among surveillance centres in Europe and USA

The current classification of human sporadic prion diseases recognizes six major phenotypic subtypes with distinctive clinicopathological features, which largely correlate at the molecular level with the genotype at the polymorphic codon 129 (methionine, M, or valine, V) in the prion protein gene and with the size of the protease-resistant core of the abnormal prion protein, PrP(Sc) (i.e. type 1 migrating at 21 kDa and type 2 at 19 kDa). We previously demonstrated that PrP(Sc) typing by Western blotting is a reliable means of strain typing and disease classification. Limitations of this approach, however, particularly in the interlaboratory setting, are the association of PrP(Sc) types 1 or 2 with more than one clinicopathological phenotype, which precludes definitive case classification if not supported by further analysis, and the difficulty of fully recognizing cases with mixed phenotypic features. In this study, we tested the inter-rater reliability of disease classification based only on histopathological criteria. Slides from 21 cases covering the whole phenotypic spectrum of human sporadic prion diseases, and also including two cases of variant Creutzfeldt-Jakob disease (CJD), were distributed blindly to 13 assessors for classification according to given instructions. The results showed good-to-excellent agreement between assessors in the classification of cases. In particular, there was full agreement (100 %) for the two most common sporadic CJD subtypes and variant CJD, and very high concordance in general for all pure phenotypes and the most common subtype with mixed phenotypic features. The present data fully support the basis for the current classification of sporadic human prion diseases and indicate that, besides molecular PrP(Sc) typing, histopathological analysis permits reliable disease classification with high interlaboratory accuracy

Clonal hematopoiesis in patients with stem cell mobilization failure:a nested case-control study

Inadequate mobilization of peripheral blood progenitor cells (PBPCs) is a limiting factor to proceeding with autologous hematopoietic cell transplantation (auto-HCT). To assess the impact of clonal hematopoiesis (CH) on mobilization failure of PBPC for auto-HCT, we investigated the characteristics of poor mobilizers (with a total PBPC collection &lt;2 × 106 CD34+ cells per kg) in a consecutive single-center cohort of 776 patients. Targeted error-corrected next-generation sequencing of 28 genes was performed in a nested case-control cohort of 90 poor mobilizers and 89 matched controls. CH was detected in 48 out of 179 patients (27%), with most patients carrying a single mutation. The presence of CH (detected at variant allele frequency [VAF] ≥ 1%) did not associate with poor mobilization potential (31% vs 22% in controls, odds ratio, 1.55; 95% confidence interval, 0.76-3.23; P = .238). PPM1D mutations were detected more often in poor mobilizers (P = .005). In addition, TP53 mutations in this cohort were detected exclusively in patients with poor mobilization potential (P = .06). The incidence of therapy-related myeloid neoplasms (t-MN) was higher among patients with mobilization failure (P = .014). Although poor mobilizers experienced worse overall survival (P = .019), this was not affected by the presence of CH. We conclude that CH at low VAF (1%-10%) is common at the time of stem cell mobilization. TP53 mutations and PPM1D mutations are associated with poor mobilization potential and their role in subsequent development of t-MN in these individuals should be established.</p