Role of cellulosic and noncellulosic membranes in hyperhomocysteinemia and oxidative stress

Hyperhomocysteinemia is an independent risk factor for cardiovascular morbidity and mortality in end-stage renal disease (ESRD) with an increased relative risk (RR) of 1% per micromol/L in total homocysteine concentration. In ESRD patients who undergo hemodialysis (HD), the antioxidant system is largely inadequate in correcting the imbalance between generation and scavenging of reactive oxygen species (ROS). To clarify the role of several cellulosic (CMs) and noncellulosic of synthetic membranes (NCMs) upon hyperhomocysteinemia and the oxidative stress, we measured plasma (P) homocysteine (t-HCY), plasma lipid peroxidation (LPO), and erythrocyte (E) concentration of several antioxidant enzymes in 20 normal subjects, in 35 HD patients treated with CMs, and in 29 patients treated with NCMs. Before, during, and after the first session of the week (at times 0', 120', end, 30' after HD end), blood samples were drawn. Plasma (P) homocysteine (t-HCY), cysteine (CYS), malondialdehyde (MDA), erythrocyte (E)-glutathione (GSH), glucose-6-phosphodehydrogenase (G6PD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and superoxide-dismutase (SOD) were determined. The dialytic procedure significantly decreased the three plasma parameters, but none normalized (as a mean). The E-enzymes scavenging ROS (lower than normal before session) increased throughout the session, but the normal range of activity was never reached. Different membranes have shown different effects. When these effects on P and E spaces were pooled, we were able to classify the membranes as follows. In a general sense, cellulosic membranes are less effective than synthetic membranes both on lipoperoxides (LPO) and antioxidant activity (AOA). Among synthetic membranes, PMMA is the best membrane both for plasma values and lesser enzymatic derangement during the session. A practical system for classifying the anti-atherosclerotic action and antioxidant activity of dialytic membranes is proposed.     

Gut microbiota as a source of a surrogate antigen that triggers autoimmunity in an immune privileged site

Recent discoveries on the role of commensal microbiota have significantly changed our understanding of human physiology. The host-microbiota interplay is now an important aspect to take into account to understand immune responses and immunological diseases. Autoimmune uveitis is a sight-threatening disease that arises without a known infectious etiology. It is unknown where and how autoreactive T cells become primed to trigger disease in the eye, which is an immune privileged site. We recently reported data supporting the notion that retina-specific T cells receive a signal in the gut from commensal microbiota-derived cross-reactive antigen(s) and trigger autoimmune uveitis in the R161H mouse model. Here we discuss our published findings, as well as our recent attempts to identify the responsible microbe(s) by using different antibiotic treatments, 16S rDNA sequencing and homology searches for candidate antigenic mimic(s) of the retinal antigen.     

The endocannabinoid 2-AG controls skeletal muscle cell differentiation via CB1 receptor-dependent inhibition of Kv7 channels

Little is known of the involvement of endocannabinoids and cannabinoid receptors in skeletal muscle cell differentiation. We report that, due to changes in the expression of genes involved in its metabolism, the levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) are decreased both during myotube formation in vitro from murine C₂C₁₂ myoblasts and during mouse muscle growth in vivo. The endocannabinoid, as well as the CB1 agonist arachidonoyl-2-chloroethylamide, prevent myotube formation in a manner antagonized by CB1 knockdown and by CB1 antagonists, which, per se, instead stimulate differentiation. Importantly, 2-AG also inhibits differentiation of primary human satellite cells. Muscle fascicles from CB1 knockout embryos contain more muscle fibers, and postnatal mice show muscle fibers of an increased diameter relative to wild-type littermates. Inhibition of K_v7.4 channel activity, which plays a permissive role in myogenesis and depends on phosphatidylinositol 4,5-bisphosphate (PIP2), underlies the effects of 2-AG. We find that CB1 stimulation reduces both total and K_v7.4-bound PIP2 levels in C₂C₁₂ cells and inhibits K_v7.4 currents in transfected CHO cells. We suggest that 2-AG is an endogenous repressor of myoblast differentiation via CB1-mediated inhibition of K_v7.4 channels.The endocannabinoid system (ECS) refers to a large group of endogenous molecules including the two major arachidonate-derived neuromodulatory mediators, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), known as endocannabinoids (EC); several enzymes involved in the metabolism of AEA (NAPE-PLD, ABDH4, GDE1, PTPN22 for biosynthesis and FAAH for degradation) and 2-AG (DAGLα and DAGLβ for biosynthesis and MAGL, ABDH6, ABDH12, and FAAH for degradation); and two G protein-coupled receptors known as cannabinoid receptor of type-1 (CB1) and type-2 (CB2). AEA also activates the cation permeant transient receptor potential vanilloid type-1 (TRPV1) channels (1). In mammals, the ECS regulates a large number of physiological processes; alterations in its activity are in fact responsible for the onset or progression of many types of disorders affecting both the central and the peripheral nervous system as well as other organs (2–5). So far, a few studies have reported that CB1 receptor activity controls key skeletal muscle metabolic processes such as insulin signaling, glucose uptake, and fatty acid oxidation (6, 7). However, little, if anything at all, is known about the expression profile and the functional role played by the ECS during skeletal muscle development.Skeletal myogenesis is a tightly regulated process that requires coordinated changes in a large number of genes allowing proliferating myoblasts to withdraw from the cell cycle and fuse to form large multinucleated myotubes (8). Several classes of ion channels play a pivotal role in the initiation of the differentiation process. For example, the sequential activation of two distinct classes of K⁺ channels, the ether-a-go-go K_v10.1 and the inward-rectifier KIR2.1 (9, 10), is known to be one of the first molecular events that causes myoblast hyperpolarization. This event, in turn, leads to the activation of voltage-dependent T-type Ca²⁺ channels, which increase the [Ca²⁺]_i necessary to initiate myoblast commitment to differentiation into myotubes (11). More recently, members of the K_v7 (KCNQ) subfamily of voltage-activated K⁺ channels have been found to be expressed in both myoblasts and myotubes (12, 13), and, in particular, it has been shown that K_v7.4 channel expression plays a permissive role in skeletal myogenesis (14).The K_v7 subfamily comprises five subunits (K_v7.1–K_v7.5), each showing distinct tissue distribution and physiological properties. K_v7 channel function is regulated by several classes of G_q/11-coupled receptors including muscarinic (15), bradikynin (16), serotonin (17), and somatostatin receptors (18). Stimulation of these receptors leads to phospholipase C (PLC) activation and subsequent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). Thus, considering that PIP2 is strictly required for K_v7 channels activity, G_q/11-coupled receptor stimulation represents one of the most important cellular mechanisms through which this subclass of K⁺ channels is kept under negative control (19). Interestingly, the M current, which is underlied by K_v7 channels, can be also inhibited following CB1 receptor stimulation by AEA at the postsynaptic level in hippocampal neurons (20) or by stimulation of the G_q/11-coupled orphan receptor GPR55 (21).In this study, we have endeavored to understand the role played by the ECS in muscle development and its impact on K_v7 activity during myogenesis by using molecular biology, biochemical, pharmacological, morphological, and electrophysiological techniques. Our results indicate that the endocannabinoid 2-AG tonically inhibits differentiation of mouse and human myoblasts via sequential activation of CB1 receptors, reduction of PIP2 levels, and inhibition of K_v7 channel activity.     

Decade-long bacterial community dynamics in cystic fibrosis airways

The structure and dynamics of bacterial communities in the airways of persons with cystic fibrosis (CF) remain largely unknown. We characterized the bacterial communities in 126 sputum samples representing serial collections spanning 8-9 y from six age-matched male CF patients. Sputum DNA was analyzed by bar-coded pyrosequencing of the V3-V5 hypervariable region of the 16S rRNA gene, defining 662 operational taxonomic units (OTUs) from >633,000 sequences. Bacterial community diversity decreased significantly over time in patients with typically progressive lung disease but remained relatively stable in patients with a mild lung disease phenotype. Antibiotic use, rather than patient age or lung function, was the primary driver of decreasing diversity. Interpatient variability in community structure exceeded intrapatient variability in serial samples. Antibiotic treatment was associated with pronounced shifts in community structure, but communities showed both short- and long-term resilience after antibiotic perturbation. There was a positive correlation between OTU occurrence and relative abundance, with a small number of persistent OTUs accounting for the greatest abundance. Significant changes in community structure, diversity, or total bacterial density at the time of pulmonary exacerbation were not observed. Despite decreasing community diversity in patients with progressive disease, total bacterial density remained relatively stable over time. These findings show the critical relationship between airway bacterial community structure, disease stage, and clinical state at the time of sample collection. These features are the key parameters with which to assess the complex ecology of the CF airway.     

Digital breast tomosynthesis and contrast‐enhanced dual‐energy digital mammography alone and in combination compared to 2D digital synthetized mammography and MR imaging in breast cancer detection and classification

To compare diagnostic performance of contrast‐enhanced dual‐energy digital mammography (CEDM) and digital breast tomosynthesis (DBT) alone and in combination compared to 2D digital mammography (MX) and dynamic contrast‐enhanced MRI (DCE‐MRI) in women with breast lesions. We enrolled 100 consecutive patients with breast lesions (BIRADS 3‐5 at imaging or clinically suspicious). CEDM, DBT, and DCE‐MRI 2D were acquired. Synthetized MX was obtained by DBT. A total of 134 lesions were investigated on 111 breasts of 100 enrolled patients: 53 were histopathologically proven as benign and 81 as malignant. Nonparametric statistics and receiver operating characteristic (ROC) curve were performed. Two‐dimensional synthetized MX showed an area under ROC curve (AUC) of 0.764 (sensitivity 65%, specificity 80%), while AUC was of 0.845 (sensitivity 80%, specificity 82%) for DBT, of 0.879 (sensitivity 82%, specificity 80%) for CEDM, and of 0.892 (sensitivity 91%, specificity 84%) for CE‐MRI. DCE‐MRI determined an AUC of 0.934 (sensitivity 96%, specificity 88%). Combined CEDM with DBT findings, we obtained an AUC of 0.890 (sensitivity 89%, specificity 74%). A difference statistically significant was observed only between DCE‐MRI and CEDM (P = .03). DBT, CEDM, CEDM combined to tomosynthesis, and DCE‐MRI had a high ability to identify multifocal and bilateral lesions with a detection rate of 77%, 85%, 91%, and 95% respectively, while 2D synthetized MX had a detection rate for multifocal lesions of 56%. DBT and CEDM have superior diagnostic accuracy of 2D synthetized MX to identify and classify breast lesions, and CEDM combined with DBT has better diagnostic performance compared with DBT alone. The best results in terms of diagnostic performance were obtained by DCE‐MRI. Dynamic information obtained by time‐intensity curve including entire phase of contrast agent uptake allows a better detection and classification of breast lesions.     

Microbiome changes associated with acute and chronic pancreatitis: A systematic review

BackgroundAltered intestinal microbiota has been reported in pancreatic disorders, however, it remains unclear whether these changes alter the course of disease in patients with acute (AP) and chronic pancreatitis (CP), or whether these disease states alter the environment to enable pathogenic microbial composition changes to occur. We undertook a systematic review to characterize the gut microbiome in pancreatitis patients.MethodsMEDLINE and EMBASE were searched for studies on microbiota in pancreatitis published from January 1, 2000 to June 5, 2020. Animal studies, reviews, case reports, and non-English articles were excluded. A frequency analysis was performed for outcomes reported in ≥2 studies and studies were analyzed for risk of bias and quality of evidence.Results22 papers met inclusion criteria; 15 included AP, 7 included CP. No studies were appropriately designed to assess whether alterations in the gut microbiome exacerbate pancreatitis or develop as a result of pancreatitis. We did identify several patterns of microbiome changes that are associated with pancreatitis. The gut microbiome demonstrated decreased alpha diversity in 3/3 A P studies and 3/3 C P studies. Beta diversity analysis revealed differences in bacterial community composition in the gut microbiome in 2/2 A P studies and 3/3 C P studies. Functionally, gut microbiome changes were associated with infectious pathways in AP and CP. Several studies suffered from high risk of bias and inadequate quality.ConclusionsDetecting differences in microbial composition associated with AP and CP may represent a diagnostic tool. Appropriately controlled longitudinal studies are needed to determine whether microbiome changes are causative or reactive in pancreatitis.