The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within ...

The Microbiota-Gut-Brain Axis

Ulcerative colitis (UC) and Crohn's disease (CD), collectively known as Inflammatory Bowel Diseases (IBD), are caused by a complex interplay between genetic, immunologic, microbial and environmental factors. Dysbiosis of the gut microbiome is increasingly considered to be causatively related to IBD and is strongly affected by components of a Western life style. Bacteria that ferment fibers and produce short chain fatty acids (SCFAs) are typically reduced in mucosa and feces of patients with IBD, as compared to healthy individuals. SCFAs, such as acetate, propionate and butyrate, are important metabolites in maintaining intestinal homeostasis. Several studies have indeed shown that fecal SCFAs levels are reduced in active IBD. SCFAs are an important fuel for intestinal epithelial cells and are known to strengthen the gut barrier function. Recent findings, however, show that SCFAs, and in particular butyrate, also have important immunomodulatory functions. Absorption of SCFAs is facilitated by substrate transporters like MCT1 and SMCT1 to promote cellular metabolism. Moreover, SCFAs may signal through cell surface G-protein coupled receptors (GPCRs), like GPR41, GPR43, and GPR109A, to activate signaling cascades that control immune functions. Transgenic mouse models support the key role of these GPCRs in controlling intestinal inflammation. Here, we present an overview of microbial SCFAs production and their effects on the intestinal mucosa with specific emphasis on their relevance for IBD. Moreover, we discuss the therapeutic potential of SCFAs for IBD, either applied directly or by stimulating SCFAs-producing bacteria through pre- or probiotic approaches.

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Short Chain Fatty Acids (SCFAs)-Mediated Gut Epithelial and Immune Regulation and Its Relevance for Inflammatory Bowel Diseases.

The colon is inhabited by a dense population of microorganisms, the so-called “gut microbiota”, able to ferment carbohydrates and proteins that escape absorption in the small intestine during digestion. This microbiota produces a wide range of metabolites, including short chain fatty acids (SCFA). These compounds are absorbed in the large bowel and are defined as 1-6 carbon volatile fatty acids which can present straight or branched-chain conformation. Their production is influenced by the pattern of food intake and diet-mediated changes in the gut microbiota. SCFA have distinct physiological effects: they contribute to shaping the gut environment, influence the physiology of the colon, they can be used as energy sources by host cells and the intestinal microbiota and they also participate in different host-signalling mechanisms. We summarize the current knowledge about the production of SCFA, including bacterial cross-feedings interactions, and the biological properties of these metabolites with impact on the human health

Intestinal Short Chain Fatty Acids and their Link with Diet and Human Health.

Short-chain fatty acids (SCFAs), the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract, are speculated to have a key role in microbiota-gut-brain crosstalk. However, the pathways through which SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, research directly exploring the role of SCFAs as potential mediators of the effects of microbiota-targeted interventions on affective and cognitive functioning is sparse, especially in humans. This Review summarizes existing knowledge on the potential of SCFAs to directly or indirectly mediate microbiota-gut-brain interactions. The effects of SCFAs on cellular systems and their interaction with gut-brain signalling pathways including immune, endocrine, neural and humoral routes are described. The effects of microbiota-targeted interventions such as prebiotics, probiotics and diet on psychological functioning and the putative mediating role of SCFA signalling will also be discussed, as well as the relationship between SCFAs and psychobiological processes. Finally, future directions to facilitate direct investigation of the effect of SCFAs on psychological functioning are outlined.

The role of short-chain fatty acids in microbiota-gut-brain communication.

A substantial body of evidence supports that the gut microbiota plays a pivotal role in the regulation of metabolic, endocrine and immune functions. In recent years, there has been growing recognition of the involvement of the gut microbiota in the modulation of multiple neurochemical pathways through the highly interconnected gut-brain axis. Although amazing scientific breakthroughs over the last few years have expanded our knowledge on the communication between microbes and their hosts, the underpinnings of microbiota-gut-brain crosstalk remain to be determined. Short-chain fatty acids (SCFAs), the main metabolites produced in the colon by bacterial fermentation of dietary fibers and resistant starch, are speculated to play a key role in neuro-immunoendocrine regulation. However, the underlying mechanisms through which SCFAs might influence brain physiology and behavior have not been fully elucidated. In this review, we outline the current knowledge about the involvement of SCFAs in microbiota-gut-brain interactions. We also highlight how the development of future treatments for central nervous system (CNS) disorders can take advantage of the intimate and mutual interactions of the gut microbiota with the brain by exploring the role of SCFAs in the regulation of neuro-immunoendocrine function.

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The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication

Butyrate, one of the SCFA, promotes the development of the intestinal barrier. However, the molecular mechanisms underlying the butyrate regulation of the intestinal barrier are unknown. To test the hypothesis that the effect of butyrate on the intestinal barrier is mediated by the regulation of the assembly of tight junctions involving the activation of the AMP-activated protein kinase (AMPK), we determined the effect of butyrate on the intestinal barrier by measuring the transepithelial electrical resistance (TER) and inulin permeability in a Caco-2 cell monolayer model. We further used a calcium switch assay to study the assembly of epithelial tight junctions and determined the effect of butyrate on the assembly of epithelial tight junctions and AMPK activity. We demonstrated that the butyrate treatment increased AMPK activity and accelerated the assembly of tight junctions as shown by the reorganization of tight junction proteins, as well as the development of TER. AMPK activity was also upregulated by butyrate during calcium switch-induced tight junction assembly. Compound C, a specific AMPK inhibitor, inhibited the butyrate-induced activation of AMPK. The facilitating effect of butyrate on the increases in TER in standard culture media, as well as after calcium switch, was abolished by compound C. We conclude that butyrate enhances the intestinal barrier by regulating the assembly of tight junctions. This dynamic process is mediated by the activation of AMPK. These results suggest an intriguing link between SCFA and the intracellular energy sensor for the development of the intestinal barrier.

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Butyrate enhances the intestinal barrier by facilitating tight junction assembly via activation of AMP-activated protein kinase in Caco-2 cell monolayers.

Objective The migration of peripherally inserted central catheters (PICCs) from the superior or inferior vena cava into the right atrium can pose a significant risk of lethal pericardial effusion and tamponade secondary to myocardial perforation. Arm movement has been reported to cause displacement of the catheter tip toward the heart and lead to ventricular tachycardia in adults. The objective of this study was to investigate whether adduction or abduction at the shoulder and flexion or extension at the elbow affect the position of PICCs placed via upper limb veins. We also hypothesized that arm movements can be used to reposition malpositioned catheters. Methods A total of 280 radiographs of 60 neonates with PICCs inserted via upper limb veins from July 2000 through June 2001 were reviewed. Differences in catheter tip position as a result of abduction versus adduction at the shoulder, flexion versus extension at the elbow, and combination changes in arm posture were determined by measurements in paired radiographs. Correction of malpositioned catheters was attempted in 10 patients by using arm movements without any alterations at the site of insertion. Results Arm movements were associated with significant displacement of catheters. Catheters that were placed via the basilic or axillary vein migrated toward the heart with adduction of the arm, whereas those that were placed via the cephalic vein moved away from the heart with adduction. Flexion of the elbow displaced catheters that were placed in the basilic or cephalic vein below the elbow toward the heart but did not have any effect on catheters that were placed via the axillary vein. For catheters that were placed in the basilic vein, simultaneous shoulder adduction and elbow flexion caused the greatest movement toward the heart (15.11 +/- 1.22 mm). We were able to reposition correctly inappropriately placed catheters in 9 of 10 patients by using arm movements. Conclusions Arm movements significantly affect the position of the tip of the PICCs. Prevention of catheter migration into the right atrium requires radiographic determination of vein of insertion and monitoring of catheter tip position with upper extremity in position of maximum inward movement of catheter for that vein. Arm movements can be used to correct the malpositioned catheters.

http://amaconsultoria.com.br/artigos/picc/changes-in-upper-extremity-position-cause-migration-of-peripherally-inserted-central-catheters-in-neonates.pdf

Changes in Upper Extremity Position Cause Migration of Peripherally Inserted Central Catheters in Neonates

Death as a complication of peripherally inserted central catheters in neonates.

Cricopharyngeal myotomy has gained widespread acceptance as surgical treatment for various forms of cervical dysphagia. The case records of 33 patients who underwent cricopharyngeal myotomy for dysphagia originating from varying underlying diseases are reviewed. The majority of these patients were able to resume oral feeding following myotomy. Analysis of preoperative pharyngoesophageal manometry and contrast radiography identified diagnostic criteria for appropriate case selection.

Cricopharyngeal Myotomy: Management of Cervical Dysphagia:

Effect of delivery room temperature on the admission temperature of premature infants: a randomized controlled trial

Robert S. Green

Papers

Butyrate enhances the intestinal barrier by facilitating tight junction assembly via activation of AMP-activated protein kinase in Caco-2 cell monolayers.

Changes in Upper Extremity Position Cause Migration of Peripherally Inserted Central Catheters in Neonates

Death as a complication of peripherally inserted central catheters in neonates.

Cricopharyngeal Myotomy: Management of Cervical Dysphagia:

Effect of delivery room temperature on the admission temperature of premature infants: a randomized controlled trial.