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Gastrointestinal physiology

Walter H Reinhart
The hematocrit (Hct) determines the oxygen carrying capacity of blood, but also increases blood viscosity and thus flow resistance. From this dual role the concept of an optimum Hct for tissue oxygenation has been derived. Viscometric studies using the ratio Hct/blood viscosity at high shear rate showed an optimum Hct of 50-60% for red blood cell (RBC) suspensions in plasma. For the perfusion of an artificial microvascular network with 5-70μm channels the optimum Hct was 60-70% for high driving pressures. With lower shear rates or driving pressures the optimum Hct shifted towards lower values...
October 21, 2016: Clinical Hemorheology and Microcirculation
Yaohong Wang, Sudeep P George, Swati Roy, Eric Pham, Amin Esmaeilniakooshkghazi, Seema Khurana
In the small intestine, epithelial cells are derived from stem cells in the crypts, migrate up the villus as they differentiate and are ultimately shed from the villus tips. This process of proliferation and shedding is tightly regulated to maintain the intestinal architecture and tissue homeostasis. Apoptosis regulates both the number of stem cells in the crypts as well as the sloughing of cells from the villus tips. Previously, we have shown that villin, an epithelial cell-specific actin-binding protein functions as an anti-apoptotic protein in the gastrointestinal epithelium...
October 21, 2016: Scientific Reports
Heni Rachmawati, Annisa Rahma, Loaye Al Shaal, Rainer H Müller, Cornelia M Keck
We have successfully developed curcumin nanosuspension intended for oral delivery. The main purpose is to improve bioavailability through enhancing its solubility. The nanoparticles were stabilized using various stabilizers, including polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), sodium carboxymethylcellulose (Na-CMC), d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), and sodium dodecyl sulfate (SDS). The average diameter of particles, microscopic appearance, and sedimentation of each preparation was observed and compared...
October 18, 2016: Scientia Pharmaceutica
Amy R Mackos, Ross Maltz, Michael T Bailey
Over the past decade, it has become increasingly evident that there are extensive bidirectional interactions between the body and its microbiota. These interactions are evident during stressful periods, where it is recognized that commensal microbiota community structure is significantly changed. Many different stressors, ranging from early life stressors to stressors administered during adulthood, lead to significant, community-wide differences in the microbiota. The mechanisms through which this occurs are not yet known, but it is known that commensal microbes can recognize, and respond to, mammalian hormones and neurotransmitters, including those that are involved with the physiological response to stressful stimuli...
October 16, 2016: Hormones and Behavior
Bruno Tilocca, Maren Witzig, Markus Rodehutscord, Jana Seifert
The chicken gastrointestinal tract (GIT) harbours a complex microbial community, involved in several physiological processes such as host immunomodulation and feed digestion. For the first time, the present study analysed dietary effects on the protein inventory of the microbiome in crop and ceca of broilers. We performed quantitative label-free metaproteomics by using 1-D-gel electrophoresis coupled with LC-MS/MS to identify the structural and functional changes triggered by diets supplied with varying amount of mineral phosphorous (P) and microbial phytase (MP)...
2016: PloS One
Linan Wang, Ning Ma, Sachiko Okamoto, Yasunori Amaishi, Eiichi Sato, Naohiro Seo, Junichi Mineno, Kazutoh Takesako, Takuma Kato, Hiroshi Shiku
Carcinoembryonic antigen (CEA) is a cell surface antigen highly expressed in various cancer cell types and in healthy tissues. It has the potential to be a target for chimeric antigen receptor (CAR)-modified T-cell therapy; however, the safety of this approach in terms of on-target/off-tumor effects needs to be determined. To address this issue in a clinically relevant model, we used a mouse model in which the T cells expressing CEA-specific CAR were transferred into tumor-bearing CEA-transgenic (Tg) mice that physiologically expressed CEA as a self-antigen...
2016: Oncoimmunology
Massimo Marzorati, Tom Van de Wiele
The gastrointestinal tract (GIT) hosts the most complex microbial community in the human body. Given the extensive metabolic potential which is present in this community, this additional organ is of key importance to maintain a healthy status and several diseases are frequently correlated with an alteration of the composition/functionality of the gut microbiota. Consequently, there is a great interest in identifying potential approaches that could modulate the microbiota and its metabolism to bring about a positive health effect...
November 2016: Journal of Clinical Gastroenterology
Sophie Thiemann, Nathiana Smit, Till Strowig
The intestinal microbiota is a diverse ecosystem containing thousands of microbial species, whose metabolic activity affects many aspects of human physiology. Large-scale surveys have demonstrated that an individual's microbiota composition is shaped by factors such as diet and the use of medications, including antibiotics. Loss of overall diversity and in some cases loss of single groups of bacteria as a consequence of antibiotic treatment in humans has been associated with enhanced susceptibility toward gastrointestinal infections and with enhanced weight gain and obesity in young children...
October 15, 2016: Current Topics in Microbiology and Immunology
Yoshiro Ishimaru, Chisayo Kozuka, Kenichiro Nakajima, Tsutomu Sasaki
At the 93rd annual meeting of the Physiological Society of Japan, a symposium entitled "Expanding frontiers in weight-control research explored by young investigators" was organized. The latest research on weight control was presented by young up-and-coming investigators. The symposium consisted of the following presentations: Gastrointestinal brush cells, immunity, and energy homeostasis; Impact of a brown rice-derived bioactive product on feeding regulation and fuel metabolism; A novel G protein-coupled receptor-regulated neuronal signaling pathway triggers sustained orexigenic effects; and NMDA receptor co-agonist D-serine regulates food preference...
October 11, 2016: Journal of Physiological Sciences: JPS
Serena Ammendola, Ylenia D'Amico, Barbara Chirullo, Rosanna Drumo, Domenico Civardelli, Paolo Pasquali, Andrea Battistoni
Zinc is known to play a central role in bacterial physiology and pathogenesis. Here, we report that the accumulation of FliC, the structural subunit of Salmonella phase 1 flagella, is sharply reduced in a znuABC Salmonella enterica sv. Typhimurium strain grown in zinc-poor media. Consequently, this mutant strain lacks motility, unless it grows in zinc-replete environments. This phenotype is the consequence of a general downregulation of all the genes involved in the biosynthesis of flagella, suggesting that zinc is the cofactor of proteins involved in the initiation of the transcriptional regulatory cascade leading to flagella assembly...
October 1, 2016: Metallomics: Integrated Biometal Science
Yo Shinoda, Yui Nakajima, Hirotoshi Iguchi, Satoshi Tatsumi, Motomitsu Kitaoka, Masahiro Nakajima, Tsutomu Takahashi, Yasuyuki Fujiwara, Teiichi Furuichi
Galacto-N-biose (GNB: Galβ1-3GalNAc) is an O-glycan disaccharide core moiety that is a core component of mucin in the gastrointestinal tract; however, the physiological properties of GNB are not well understood. Glutamate excitotoxicity causes neuronal death in acute neurological disorders including stroke, trauma, and neurodegenerative disease. Therefore the discovery of drugs to treat glutamate excitotoxicity is an important goal. Here, we report that GNB is neuroprotective against glutamate-induced excitotoxicity...
October 8, 2016: European Journal of Pharmacology
Braedon McDonald, Paul Kubes
The sterile inflammatory response (inflammation in the absence of infection) to tissue injury and cell death is required for normal wound healing. However, dysregulated sterile inflammation leads to various acute and chronic inflammatory diseases, including those of the liver and gastrointestinal tract. It is therefore important to increase our understanding of the mechanisms that control physiologic vs pathologic sterile inflammation. We have begun to clarify the cellular and molecular mechanisms that coordinate the innate immune response to tissue damage and cell death in the liver...
October 7, 2016: Gastroenterology
Xiaoxia Yang, John Duan, Jeffrey Fisher
A previously presented physiologically-based pharmacokinetic model for immediate release (IR) methylphenidate (MPH) was extended to characterize the pharmacokinetic behaviors of oral extended release (ER) MPH formulations in adults for the first time. Information on the anatomy and physiology of the gastrointestinal (GI) tract, together with the biopharmaceutical properties of MPH, was integrated into the original model, with model parameters representing hepatic metabolism and intestinal non-specific loss recalibrated against in vitro and in vivo kinetic data sets with IR MPH...
2016: PloS One
Robert R Brubaker
This chapter outlines the physiology of Yersinia pestis with emphasis on identifying unique functions required for tissue invasion and acute disease. These activities are opposed to often incompatible processes expressed by very closely related Yersinia pseudotuberculosis, which causes localized gastrointestinal infection. Gain of new information in Y. pestis entailed lateral transfer of plasminogen activator and anti-phagocytic capsular antigen via the plasmids pPCP and pMT, respectively, and derepression of the pigmentation locus facilitating colonization of the flea vector...
2016: Advances in Experimental Medicine and Biology
M A Jimoh, W MacNaughtan, H E L Williams, D Greetham, R L Linforth, I D Fisk
The nature of and factors effecting sodium interactions with psyllium were investigated in vitro. In a batch extraction system, psyllium mucilage gel retained at least 50% of sodium across a range of concentrations (5-300 mg sodium per g psyllium) and pH (2-10) environments. FTIR and Na NMR analyses of psyllium gels indicated that binding was complex with non-specific multi-site interactions. The potential use of psyllium husk as a binding agent for the reduction of bioavailable sodium was therefore evaluated...
September 14, 2016: Food & Function
Emma Elison, Louise K Vigsnaes, Laura Rindom Krogsgaard, Julie Rasmussen, Nikolaj Sørensen, Bruce McConnell, Thierry Hennet, Morten O A Sommer, Peter Bytzer
The gut microbiota has been established as an important player influencing many aspects of human physiology. Breast milk, the first diet for an infant, contains human milk oligosaccharides (HMO) that shape the infant's gut microbiota by selectively stimulating the growth of specific bacteria, especially bifidobacteria. In addition to their bifidogenic activity, the ability of HMO to modulate immune function and the gut barrier makes them prime candidates to restore a beneficial microbiota in dysbiotic adults and provide health benefits...
October 2016: British Journal of Nutrition
Harlan M Krumholz, Angela Hsieh, Rachel P Dreyer, John Welsh, Nihar R Desai, Kumar Dharmarajan
BACKGROUND: The risk of rehospitalization is elevated in the immediate post-discharge period and declines over time. It is not known if the extent and timing of risk vary across readmission diagnoses, suggesting that recovery and vulnerability after discharge differ by physiologic system. OBJECTIVE: We compared risk trajectories for major readmission diagnoses in the year after discharge among all Medicare fee-for-service beneficiaries hospitalized with heart failure (HF), acute myocardial infarction (AMI), or pneumonia from 2008-2010...
2016: PloS One
M Chinonye Udechukwu, Stephanie A Collins, Chibuike C Udenigwe
Zinc is an essential micronutrient that strongly influences human health and nutrition through its involvement in several biological processes. Zinc functions as structural and functional component of many transcription factors and enzymes that regulate cell growth, gene expression, and immune response, and its deficiency can lead to retarded growth and impaired immune functions. The physiological functions of zinc are dependent on its bioavailability in tissues, which in turn depends on intestinal absorption of dietary zinc...
October 12, 2016: Food & Function
Clint A Holm, Leon Pahler, Matthew S Thiese, Rodney Handy
BACKGROUND: Monitoring core body temperature to identify heat strain in workers engaged in hot work in heat stress environments is intrusive and expensive. Nonintrusive, inexpensive methods are needed to calculate individual Physiological Strain Index (PSI). OBJECTIVE: Thermal imaging and heart rate monitoring were used in this study to calculate Physiological Strain Index (PSI) from thermal imaging temperatures of human subjects wearing thermal protective garments during recovery from hot work...
October 2016: Journal of Thermal Biology
Julia M Selfridge, Tetsuya Gotoh, Samuel Schiffhauer, JingJing Liu, Philip E Stauffer, Andrew Li, Daniel G S Capelluto, Carla V Finkielstein
Circadian rhythms are a collection of endogenously driven biochemical, physiological, and behavioral processes that oscillate in a 24-h cycle and can be entrained by external cues. Circadian clock molecules are responsible for the expression of regulatory components that modulate, among others, the cell's metabolism and energy consumption. In clinical practice, the regulation of clock mechanisms is relevant to biotransformation of therapeutics. Accordingly, xenobiotic metabolism and detoxification, the two processes that directly influence drug effectiveness and toxicity, are direct manifestations of the daily oscillations of the cellular and biochemical processes taking place within the gastrointestinal, hepatic/biliary, and renal/urologic systems...
October 3, 2016: Drugs
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