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IUBMB Life Apr 2019Vitamin E is an essential molecule for our development and health. It has long been thought that it was absorbed and transported through cellular membranes by a passive... (Review)
Review
Vitamin E is an essential molecule for our development and health. It has long been thought that it was absorbed and transported through cellular membranes by a passive diffusion process. However, data obtained during the past 15 years showed that its absorption is actually mediated, at least in part, by cholesterol membrane transporters including the scavenger receptor class B type I (SR-BI), CD36 molecule (CD36), NPC1-like transporter 1 (NPC1L1), and ATP-binding cassettes A1 and G1 (ABCA1 and ABCG1). This review focuses on the absorption process of vitamin E across the enterocyte. A special attention is given to the regulation of this process, including the possible competition with other fat-soluble micronutrients, and the modulation of transporter expressions. Overall, recent results noticeably increased the comprehension of vitamin E intestinal transport, but additional investigations are still required to fully appreciate the mechanisms governing vitamin E bioavailability. © 2018 IUBMB Life, 71(4):416-423, 2019.
Topics: ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Animals; Biological Availability; Biological Transport; CD36 Antigens; Chylomicrons; Enterocytes; Humans; Intestinal Absorption; Membrane Transport Proteins; Vitamin E
PubMed: 30308094
DOI: 10.1002/iub.1955 -
Communications Biology Aug 2021The position of abdominal organs, and mechanisms by which these are centrally connected, are currently described in peritoneal terms. As part of the peritoneal model of...
The position of abdominal organs, and mechanisms by which these are centrally connected, are currently described in peritoneal terms. As part of the peritoneal model of abdominal anatomy, there are multiple mesenteries. Recent findings point to an alternative model in which digestive organs are connected to a single mesentery. Given that direct evidence of this is currently lacking, we investigated the development and shape of the entire mesentery. Here we confirm that, within the abdomen, there is one mesentery in which all abdominal digestive organs develop and remain connected to. We show that all abdominopelvic organs are organised into two, discrete anatomical domains, the mesenteric and non-mesenteric domain. A similar organisation occurs across a range of animal species. The findings clarify the anatomical foundation of the abdomen; at the foundation level, the abdomen comprises a visceral (i.e. mesenteric) and somatic (i.e. musculoskeletal) frame. The organisation at that level is a fundamental order that explains the positional anatomy of all abdominopelvic organs, vasculature and peritoneum. Collectively, the findings provide a novel start point from which to systemically characterise the abdomen and its contents.
Topics: Humans; Mesentery; Peritoneum
PubMed: 34408242
DOI: 10.1038/s42003-021-02496-1 -
Wiley Interdisciplinary Reviews.... Jul 2018Efficient absorption of nutrients by the intestine is essential for life. In mammals and birds, convolution of the intestinal surface into finger-like projections called... (Review)
Review
Efficient absorption of nutrients by the intestine is essential for life. In mammals and birds, convolution of the intestinal surface into finger-like projections called villi is an important adaptation that ensures the massive surface area for nutrient contact that is required to meet metabolic demands. Each villus projection serves as a functional absorptive unit: it is covered by a simple columnar epithelium that is derived from endoderm and contains a mesodermally derived core with supporting vasculature, lacteals, enteric nerves, smooth muscle, fibroblasts, myofibroblasts, and immune cells. In cross section, the consistency of structure in the billions of individual villi of the adult intestine is strikingly beautiful. Villi are generated in fetal life, and work over several decades has revealed that villus morphogenesis requires substantial "crosstalk" between the endodermal and mesodermal tissue components, with soluble signals, cell-cell contacts, and mechanical forces providing specific dialects for sequential conversations that orchestrate villus assembly. A key part of this process is the formation of subepithelial mesenchymal cell clusters that act as signaling hubs, directing overlying epithelial cells to cease proliferation, thereby driving villus emergence and simultaneously determining the location of future stem cell compartments. Interestingly, distinct species-specific differences govern how and when tissue-shaping signals and forces generate mesenchymal clusters and control villus emergence. As the details of villus development become increasingly clear, the emerging picture highlights a sophisticated local self-assembled cascade that underlies the reproducible elaboration of a regularly patterned field of absorptive villus units. This article is categorized under: Vertebrate Organogenesis > From a Tubular Primordium: Non-Branched Comparative Development and Evolution > Organ System Comparisons Between Species Early Embryonic Development > Development to the Basic Body Plan.
Topics: Animals; Epithelial Cells; Humans; Intestinal Mucosa; Mice; Microvilli; Organogenesis; Rats; Signal Transduction; Species Specificity
PubMed: 29513926
DOI: 10.1002/wdev.317 -
Thorax Jul 1972The history of the investigations into interalveolar communications (pores of Kohn) shows that the question whether they exist and, if so, their nature has for...
The history of the investigations into interalveolar communications (pores of Kohn) shows that the question whether they exist and, if so, their nature has for approximately a century been contentious. The present electron microscopic study of the lungs of mice demonstrates that alveolar pores are normal structures, with edges composed of intact alveolar wall. A number of planes are demonstrated from which a fully compatible reconstruction is made. It is concluded that pores are round or oval structures frequently having at least one type II alveolar cell forming part of their boundary. It is further postulated that pores may be divided by a capillary column stretching across the space, resulting in two openings. A type II alveolar cell forming part of the pore wall may straddle the capillary column. Alveolar macrophages may be found lying free in the pore or lying astride a capillary column. When lying in a corner position type II cells may occupy the full wall thickness and face into three alveoli.
Topics: Animals; Basement Membrane; Capillaries; Epithelial Cells; Macrophages; Male; Mice; Microscopy, Electron; Pulmonary Alveoli
PubMed: 5075613
DOI: 10.1136/thx.27.4.433 -
Allergology International : Official... Jul 2022The nervous system and the immune system individually play important roles in regulating the processes necessary to maintain physiological homeostasis, respond to acute... (Review)
Review
The nervous system and the immune system individually play important roles in regulating the processes necessary to maintain physiological homeostasis, respond to acute stress and protect against external threats. These two regulating systems for maintaining the living body had often been assumed to function independently. Allergies develop as a result of an overreaction of the immune system to substances that are relatively harmless to the body, such as food, pollen and dust mites. Therefore, it has been generally supposed that the development and pathogenesis of allergies can be explained through an immunological interpretation. Recently, however, neuro-immune crosstalk has attracted increasing attention. Consequently, it is becoming clear that there is close morphological proximity and physiological and pathophysiological interactions between neurons and immune cells in various peripheral tissues. Thus, researchers are now beginning to appreciate that neuro-immune interactions may play a role in tissue homeostasis and the pathophysiology of immune-mediated disease, but very little information is available on the molecular basis of these interactions. Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host-pathogen interactions. Mast cells are ubiquitous in the body, and these cells are often found in close proximity to nerve fibers in various tissues, including the lamina propria of the intestine. Mast cells and neurons are thought to communicate bidirectionally to modulate neurophysiological effects and mast cell functions, which suggests that neuro-immune interactions may be involved in the pathology of allergic diseases.
Topics: Food Hypersensitivity; Humans; Mast Cells; Mucous Membrane; Neuroimmunomodulation; Neurons
PubMed: 35410807
DOI: 10.1016/j.alit.2022.03.004 -
Annals of the American Thoracic Society Nov 2018The respiratory system is protected from inhaled particles and microbes by the mucociliary system. This system differs between animal species, where pigs and humans have... (Review)
Review
The respiratory system is protected from inhaled particles and microbes by the mucociliary system. This system differs between animal species, where pigs and humans have numerous submucosal glands. The polymer-forming mucin, MUC5B, is packed in a highly organized way in granules of the mucus-secreting cells in the glands. Upon secretion, the packed MUC5B is flushed out by a chloride- and bicarbonate-rich fluid from the cystic fibrosis transmembrane conductance regulator-expressing serosal cells located at the most distal part of the gland. The bicarbonate raises the pH and removes calcium from the N terminus of MUC5B, allowing the mucin to be pulled out into a linear polymer. Thousands of such polymers gather in bundles in the submucosal gland duct, and these bundles appear at the opening of the glands. They are moved by the beating cilia, and sweep over the airway surface and are patchily coated with the MUC5AC mucin from the surface goblet cells. The movement of these bundles is controlled by the MUC5AC mucin attachment/detachment to the goblet cells. Thus, higher animals with submucosal glands and large diameters of the proximal airways are efficiently cleaned by the thick mucus bundles sweeping the airway surface and moving particles and bacteria toward the larynx.
Topics: Animals; Disease Models, Animal; Humans; Lung Diseases; Mucins; Mucociliary Clearance; Respiratory Mucosa; Secretory Vesicles; Swine
PubMed: 30431338
DOI: 10.1513/AnnalsATS.201804-238AW -
Hearing Research Sep 2022In the cochlea, mechano-electrical transduction is preceded by dynamic range compression. Outer hair cells (OHCs) and their voltage dependent length changes, known as... (Review)
Review
In the cochlea, mechano-electrical transduction is preceded by dynamic range compression. Outer hair cells (OHCs) and their voltage dependent length changes, known as electromotility, play a central role in this compression process, but the exact mechanisms are poorly understood. Here we review old and new experimental findings and show that (1) just audible high-frequency tones evoke an ∼1-microvolt AC receptor potential in basal OHCs; (2) any mechanical amplification of soft high-frequency tones by OHC motility would have an adverse effect on their audibility; (3) having a higher basolateral K+ conductance, while increasing the OHC corner frequency, does not boost the magnitude of the high-frequency AC receptor potential; (4) OHC receptor currents display a substantial rectified (DC) component; (5) mechanical DC responses (baseline shifts) to acoustic stimuli, while insignificant on the basilar membrane, can be comparable in magnitude to AC responses when recorded in the organ of Corti, both in the apex and the base. In the basal turn, the DC component may even exceed the AC component, lending support to Dallos' suggestion that both apical and basal OHCs display a significant degree of rectification. We further show that (6) low-intensity cochlear traveling waves, by virtue of their abrupt transition from fast to slow propagation, are well suited to transport high-frequency energy with minimal losses (∼2-dB loss for 16-kHz tones in the gerbil); (7) a 90-dB, 16-kHz tone, if transmitted without loss to its tonotopic place, would evoke a destructive displacement amplitude of 564 nm. We interpret these findings in a framework in which local dissipation is regulated by OHC motility. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
Topics: Acoustic Stimulation; Basilar Membrane; Cochlea; Hair Cells, Auditory, Outer; Hair Cells, Vestibular
PubMed: 34686384
DOI: 10.1016/j.heares.2021.108367 -
Frontiers in Immunology 2021Intra-amniotic infection and inflammation (IAI) affect fetal development and are highly associated with preterm labor and premature rupture of membranes, which often... (Review)
Review
Intra-amniotic infection and inflammation (IAI) affect fetal development and are highly associated with preterm labor and premature rupture of membranes, which often lead to adverse neonatal outcomes. Human amniotic membrane (hAM), the inner part of the amnio-chorionic membrane, protects the embryo/fetus from environmental dangers, including microbial infection. However, weakened amnio-chorionic membrane may be breached or pathogens may enter through a different route, leading to IAI. The hAM and human amniotic fluid (hAF) respond by activation of all components of the innate immune system. This includes changes in 1) hAM structure, 2) presence of immune cells, 3) pattern recognition receptors, 4) cytokines, 5) antimicrobial peptides, 6) lipid derivatives, and 7) complement system. Herein we provide a comprehensive and integrative review of the current understanding of the innate immune response in the hAM and hAF, which will aid in design of novel studies that may lead to breakthroughs in how we perceive the IAI.
Topics: Amnion; Amniotic Fluid; Animals; Bacteria; Bacterial Infections; Chorioamnionitis; Female; Host-Pathogen Interactions; Humans; Immunity, Innate; Obstetric Labor, Premature; Pregnancy; Pregnancy Complications, Infectious; Premature Birth; Signal Transduction
PubMed: 34745106
DOI: 10.3389/fimmu.2021.735324 -
Sheng Li Xue Bao : [Acta Physiologica... Aug 2016Epicardium is one of the important components of the heart and plays a critical role in cardiogenesis. Moreover, further studies have shown that epicardium contributes... (Review)
Review
Epicardium is one of the important components of the heart and plays a critical role in cardiogenesis. Moreover, further studies have shown that epicardium contributes to post-injury heart regeneration. After heart injury, epicardium secretes various signaling factors, regulating the cardiomyocyte proliferation and neovascularization. In addition, epicardium differentiates into many kinds of cells which take part in the heart repair in response to heart damage. In this review, we summarize recent progress on epicardial function, related signaling pathways and the potential clinical application, and provide a reference for future studies in epicardium and heart regeneration.
Topics: Heart; Pericardium; Regeneration; Signal Transduction
PubMed: 27546512
DOI: No ID Found -
Biochimica Et Biophysica Acta Sep 2014There are many peptides known that inhibit the entry of enveloped viruses into cells, including one peptide that is successfully being used in the clinic as a drug. In... (Review)
Review
There are many peptides known that inhibit the entry of enveloped viruses into cells, including one peptide that is successfully being used in the clinic as a drug. In this review, we discuss the discovery, antiviral activity and mechanism of action of such peptides. While peptide entry inhibitors have been discovered by a wide variety of approaches (structure-based, accidental, intentional, rational and brute force) we show here that they share a common physical chemical property: they are at least somewhat hydrophobic and/or amphipathic and have a propensity to interact with membrane interfaces. We propose that this propensity drives a shared mechanism of action for many peptide entry inhibitors, involving direct interactions with viral and cellular membranes, as well as interactions with the complex hydrophobic protein/lipid interfaces that are exposed, at least transiently, during virus-cell fusion. By interacting simultaneously with the membrane interfaces and other critical hydrophobic surfaces, we hypothesize that peptide entry inhibitors can act by changing the physical chemistry of the membranes, and the fusion protein interfaces bridging them, and by doing so interfere with the fusion of cellular and viral membranes. Based on this idea, we propose that an approach that focuses on the interfacial hydrophobicity of putative entry inhibitors could lead to the efficient discovery of novel, broad-spectrum viral entry inhibitors. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
Topics: Cell Membrane; Genome, Viral; Hydrophobic and Hydrophilic Interactions; Membrane Fusion; Membranes; Peptides; Protein Conformation; Viral Envelope Proteins; Viral Fusion Proteins; Virion
PubMed: 24780375
DOI: 10.1016/j.bbamem.2014.04.015