Gastrointestinal mucus, a medium for survival and for elimination of parasitic nematodes and protozoa

Parasitology ◽  
1987 ◽  
Vol 94 (S1) ◽  
pp. S77-S100 ◽  
Author(s):  
H. R. P. Miller
Keyword(s):  
Physical Properties ◽  
Elastic Material ◽  
Molecular Level ◽  
Mucosal Surface ◽  
Parasitic Nematodes ◽  
Physical Injury ◽  
Mucin Glycoproteins ◽  
Mucosal Surfaces ◽  
Additional Support

Mucus is a sticky visco-elastic material which coats all mucosal surfaces. Florey, in 1955, noted the following three functions for gastrointestinal mucus: protection of the underlying mucosa from chemical and physical injury, lubrication of the mucosal surface to facilitate passage of luminal contents, and removal of parasites by binding and entrapment. In the 31 years since Florey's review, detailed analyses of the composition of mucus and of the biochemistry of mucin glycoproteins, as well as measurements of the physical properties of mucus from different organs and sites have yielded information at the molecular level which provide additional support for his views on its function (Allen, 1981; Forstner, Wesley & Forstner, 1982).

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

scholarly journals Heterogeneous strains in tissue collagen show that high strains locally suppress degradation by collagenase

2021 ◽  
Author(s):  
K. Saini ◽  
M. Tiwari ◽  
S. Cho ◽  
A. Jalil ◽  
M. Vashisth ◽  
...  
Keyword(s):  
Physical Properties ◽  
Degradation Rate ◽  
Molecular Level ◽  
Second Harmonic ◽  
Mechanical Strain ◽  
Collagen Content ◽  
Peak Strain ◽  
Tendon Tissue ◽  
Physiological Strain ◽  
Matrix Metalloproteinase 1

AbstractCollagen, the most abundant protein in mammals, contributes to the physical properties of different tissues during development, homeostasis, and disease. The adaptation of physical properties of tissues to mechanical stimuli is thus dependent on the control of tissue collagen levels by well-regulated synthesis and degradation of collagen. Importantly, how various molecular-level events within a tissue sustaining a range of mechanical strains contribute towards maintaining its collagen levels, remains unclear to date. Such molecular level processes in tissues are studied here in the case of isolated tendons consisting of collagen fibrils oriented along tissue loading-axis and beating embryonic hearts to gain understanding of mechanical load dependent tissue sculpting. Using a novel bioreactor design, starved mice tail tendon fascicles were used as a “cell-free” model and were subjected to heterogeneous and uniaxial deformation modes. Patterned photobleaching of fluorescent probes, a novel Aza-peptide or dye, on fascicles used to quantify tissue strains. Tissue microstructure was simultaneously imaged using second harmonic generation (SHG) signal to assess tissue collagen content while deformed fascicle samples were exposed to purified matrix metalloproteinase-1 (MMP-1) or bacterial collagenase (BC). A decrease in the degradation rate (relative to strain-free) was observed for physiological strain limits of tendon tissue (i.e. ∼5-8%) while at higher strains (i.e. pathological) the degradation rate was independent of strain magnitude changes. Interestingly, the strain dependence of degradation rate was independent of cleavage-site specificity of the collagenase molecules and the mode of tendon tissue deformation. Although spatially different within a tissue sample, the values of strain, degradation rate and collagen fiber organization with time during degradation of each tendon fascicle region were highly correlated. Tendon regions dominated by collagen fibers inclined to fascicle-axis were observed to follow non-affine deformation. The dependence of the degradation rate on mechanical strain is due to sequestration of collagen cleavage sites within fibrils. Permeation, tissue mass density and mobility of fluorescent collagenase and dextran are strain-independent for fascicle strains up to ∼5-8% while the degradation rate is positively correlated to unfolded triple-helical collagen content. Normal beating chick hearts subjected to ∼5% peak strain in a spatiotemporal coordinate contractile wave were observed to maintain their collagen mass until the beating strain is suppressed by inhibition of myosin-II. Based on the presence of exogeneous MMP inhibitors, endogenous MMPs within the non-beating hearts degrade the collagens immediately (in ∼30-60 mins). Both tissue systems under mechanical strains suggest degradative sculpting where mechanical strain-dependent collagen fibril architecture changes appear to play a key role in determining collagen lifetime within tissues.Graphical abstract

Aspects of Immunology of the Gut and Rotavirus Infection

1993 ◽  
Vol 1993 ◽  
pp. 32-32
Author(s):  
Geoffrey Oldham
Keyword(s):  
Immune Responses ◽  
Mucosal Immunity ◽  
Mucosal Surface ◽  
Pathogenic Microorganisms ◽  
Subsequent Infection ◽  
Mucosal Surfaces ◽  
Artificial Induction ◽  
Enteric Infections ◽  
Portal Of Entry ◽  
Immune Defences

The major portal of entry for most pathogenic microorganisms is the mucosal surface. It seems reasonable therefore that the host in its turn should possess substantial immune defences at the mucosae to provide protection against these insults. Enteric infections usually result in at least some degree of specific protection against a subsequent infection with the same organism. However artificial induction of mucosal immunity has proved difficult. Clearly, as yet, we do not have a full understanding of the inductive events involved in the generation of mucosal immune responses or the immune mechanisms operating at mucosal surfaces. In this paper I will attempt to briefly review the main aspects of mucosal immunity concentrating on the gut as the model mucosal surface.

scholarly journals Movement of Sodium Across the Mucosal Surface of the Isolated Toad Bladder and its Modification by Vasopressin

1962 ◽  
Vol 45 (3) ◽  
pp. 529-543 ◽  
Author(s):  
Howard S. Frazier ◽  
Eleanor F. Dempsey ◽  
Alexander Leaf
Keyword(s):  
Epithelial Cells ◽  
Initial Step ◽  
Sodium Content ◽  
Mucosal Surface ◽  
Transepithelial Transport ◽  
Tissue Water ◽  
Chemical Gradients ◽  
Mucosal Surfaces ◽  
Toad Bufo ◽  
Stimulation Of

Studies have been made on the isolated urinary bladder of the toad, Bufo marinus, in an attempt to evaluate gradients of chemical activity across the mucosal surfaces of the epithelial cells which would serve to maintain a net movement of sodium from the mucosal medium into the cells. The likelihood of such chemical gradients has been established by the demonstration of lower contents of sodium within the tissue, expressed as microequivalents per gram of tissue water, than of concentrations of sodium in the mucosal medium at all levels of the latter examined. The transepithelial transport of sodium and the sodium content of the tissue were found to increase rapidly with rise in concentration of sodium in the mucosal medium up to values of 30 to 60 meq per liter. Further increase in concentration of the medium above this value failed to induce further stimulation of sodium transport or increase in the sodium content of the tissue. Vasopressin increased the rate of transport of sodium at every concentration of sodium in the mucosal medium without altering this relationship. Although entry of sodium across the mucosal surface of the epithelial cells may be passive it is not by free diffusion but involves some considerable interaction with the mucosal surface of the bladder and constitutes the major determinant of the rate of transepithelial transport of sodium. Vasopressin acts to enhance this initial step in the transport of sodium.

NEW LOOK AND APPROACH TO PHYSICAL AND QUANTUM PROPERTIES OF PHOTON

2020 ◽  
Vol 2 (3(72)) ◽  
pp. 25-36
Author(s):  
S.N. Grigorev-Fridman
Keyword(s):  
Elementary Particle ◽  
Physical Properties ◽  
Long Range ◽  
Molecular Level ◽  
Photon Absorption ◽  
Time And Space ◽  
Quantum Properties ◽  
New Look

New physical properties of photon as quasineutral elementary particle were revealed at the atomic-molecular level of interaction of radiation and photon absorption during the transition of electrons from external, remote orbits atoms of matter to lower orbit of rotation around the nucleus of atoms. Empirically discovered rapidly changing in time and space, its own orbital negative and positive charges of photon. The use of the idea of Russian scientists about the presence of photon its own orbital charge constantly changing in time and space when creating super-powerful and long-range combat laser is considered.

scholarly journals STRUCTURE OF THE TOAD'S URINARY BLADDER AS RELATED TO ITS PHYSIOLOGY

1961 ◽  
Vol 10 (4) ◽  
pp. 529-553 ◽  
Author(s):  
Lee D. Peachey ◽  
Howard Rasmussen
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Urinary Bladder ◽  
Plasma Membranes ◽  
Goblet Cells ◽  
Mucosal Surface ◽  
In Vitro Experiments ◽  
Granular Component ◽  
Mucosal Surfaces

The structure of the urinary bladder of the toad Bufo marinus was studied by light and electron microscopy. The epithelium covering the mucosal surface of the bladder is 3 to 10 microns thick and consists of squamous epithelial cells, goblet cells, and a third class of cells containing many mitochondria and possibly representing goblet cells in early stages of their secretory cycle. This epithelium is supported on a lamina propria 30 to several hundred microns thick and containing collagen fibrils, bundles of smooth muscle fibers, and blood vessels. The serosal surface of the bladder is covered by an incomplete mesothelium. The cytoplasm of the squamous epithelial cells, which greatly outnumber the other types of cells, is organized in a way characteristic of epithelial secretory cells. Mitochondria, smooth and rough surfaced endoplasmic reticulum, a Golgi apparatus, "multivesicular bodies," and isolated particles and vesicles are present. Secretion granules are found immediately under the plasma membranes of the free surfaces of the epithelial cells and are seen to fuse with these membranes and release their contents to contribute to a fibrous surface coating found only on the free mucosal surfaces of the cells. Beneath the plasma membranes on these surfaces is an additional, finely granular component. Lateral and basal plasma membranes are heavily plicated and appear ordinary in fine structure. The cells of the epithelium are tightly held together by a terminal bar apparatus and sealed together, with an intervening space of only 0.02 mµ near the bladder lumen, in such a way as to prevent water leakage between the cells. It is demonstrated in in vitro experiments that water traversing the bladder wall passes through the cytoplasm of the epithelial cells and that a vesicle transport mechanism is not involved. In vitro experiments also show that the basal (serosal) surfaces of the epithelial cells are freely permeable to water, while the free (mucosal) surfaces are normally relatively impermeable but become permeable when the serosal surface of the bladder is treated with neurohypophyseal hormones. The permeability barrier found at the mucosal surface may be represented, structurally, either by the filamentous layer lying external to the plasma membrane, by the intracellular, granular component found just under the plasma membrane, or by both of these components of the mucosal surface complex. The polarity of the epithelial sheet is emphasized and related to the physiological role of the urinary bladder in amphibian water balance mechanisms.

Redox-Active Benzoquinones as Challenging “non-innocent” Linkers to Construct 2D Frameworks and Nanostructures with tunable Physical Properties

2022 ◽  
Author(s):  
Noemi N. Monni ◽  
Marco Sanna Angotzi ◽  
Mariangela M. Oggianu ◽  
Suchithra S. Ashoka Sahadevan ◽  
Maria Laura Mercuri
Keyword(s):  
Physical Properties ◽  
Coordination Polymers ◽  
Molecular Level ◽  
Metal Organic Frameworks ◽  
Redox Activity ◽  
Redox Active ◽  
Metal Organic

Exploiting redox activity in supramolecular frameworks such as coordination polymers, metal-organic frameworks and related nanostructures is of paramount importance both at the molecular level and for their technological applications, since...

scholarly journals Nonpolar Inactivation of the Hypervariable Streptococcal Inhibitor of Complement Gene (sic) in Serotype M1 Streptococcus pyogenes Significantly Decreases Mouse Mucosal Colonization

2000 ◽  
Vol 68 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Slawomir Lukomski ◽  
Nancy P. Hoe ◽  
Iman Abdi ◽  
Jacqueline Rurangirwa ◽  
Parichher Kordari ◽  
...  
Keyword(s):  
Mucosal Surface ◽  
Upper Respiratory Tract ◽  
Complement Protein ◽  
Gene Encoding ◽  
Mucosal Surfaces ◽  
Group A ◽  
Complement Gene ◽  
Colonization Ability ◽  
Upper Respiratory ◽  
Human Infections

ABSTRACT Group A Streptococcus (GAS) is a human pathogen that commonly infects the upper respiratory tract. GAS serotype M1 strains are frequently isolated from human infections and contain the gene encoding the hypervariable streptococcal inhibitor of complement protein (Sic). It was recently shown that Sic variants were rapidly selected on mucosal surfaces in epidemic waves caused by M1 strains, an observation suggesting that Sic participates in host-pathogen interactions on the mucosal surface (N. P. Hoe, K. Nakashima, S. Lukomski, D. Grigsby, M. Liu, P. Kordari, S.-J. Dou, X. Pan, J. Vuopio-Varkila, S. Salmelinna, A. McGeer, D. E. Low, B. Schwartz, A. Schuchat, S. Naidich, D. De Lorenzo, Y.-X. Fu, and J. M. Musser, Nat. Med. 5:924–929, 1999). To test this idea, a new nonpolar mutagenesis method employing a spectinomycin resistance cassette was used to inactivate the sic gene in an M1 GAS strain. The isogenic Sic-negative mutant strain was significantly (P < 0.019) impaired in ability to colonize the mouse mucosal surface after intranasal infection. These results support the hypothesis that the predominance of M1 strains in human infections is related, in part, to a Sic-mediated enhanced colonization ability.

scholarly journals A STUDY OF PNEUMOCOCCAL MERODIPLOIDS AT THE MOLECULAR LEVEL

Genetics ◽  
1975 ◽  
Vol 81 (1) ◽  
pp. 9-19
Author(s):  
S V S Kashmiri ◽  
Rollin D Hotchkiss
Keyword(s):  
Biological Activity ◽  
Physical Properties ◽  
Resistant Strain ◽  
Genetic Basis ◽  
Tandem Duplication ◽  
Molecular Level ◽  
Detailed Examination ◽  
Gene Region ◽  
Pneumococcal Strain ◽  
Activity Ratios

ABSTRACT The DNA of a sulfonamide-resistant Pneumococcal strain (heterozygous for sulr-c) and that of three highly resistant and persistently heterozygous cd transformants, derived by introducing sulr-c marker into a stable sulfonamide resistant strain (sulr-d), were studied to analyze the genetic basis of their merodiploidy. The physical properties of the native and denatured DNA from the heterozygotes and the nonheterozygous strains were not distinguishable. The denaturability and the renaturability of biological activity for the heterozygous markers were essentially identical to those of the normal markers. The heterozygosity extends to the closely linked locus giving rise to four different configurations of cd and cd  + transformants, characterized by their frequencies of segregation and donor-marker activities. The marker-activity ratios and the frequency of co-transfer of heterozygous markers were found to remain the same in each when the donor DNA was native, denatured or reannealed without fractionation or reannealed after remixing of resolved strands. Possible models were weighed against these observations and these considerations led to the suggestion that tandem duplication of a gene region may be responsible for the heterozygosity and instability of this region. A more detailed examination of this model will be presented in an accompanying paper.

scholarly journals Elucidating bacterial adhesion to mucosal surface by an original AFM approach

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Karen Dunker ◽  
Sol Gomez de la Torre Canny ◽  
Catherine Taylor Nordgård ◽  
Etienne Dague ◽  
Cécile Formosa-Dague ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Aeromonas Salmonicida ◽  
Mucosal Surface ◽  
Fish Skin ◽  
Surrounding Water ◽  
Protective Function ◽  
Mucosal Surfaces ◽  
Afm Probe ◽  
Adhesive Interactions ◽  
Skin Mucosa

Abstract Background Fish skin represents an ancient vertebrate mucosal surface, sharing characteristics with other mucosal surfaces including those of the intestine. The skin mucosa is continuously exposed to microbes in the surrounding water and is therefore important in the first line defense against environmental pathogens by preventing bacteria from accessing the underlying surfaces. Understanding the microbe-host interactions at the fish skin mucosa is highly relevant in order to understand and control infection, commensalism, colonization, persistence, infection, and disease. Here we investigate the interactions between the pathogenic bacteria Aeromonas salmonicida (A. salmonicida) and Yersinia ruckeri (Y. ruckeri), respectively, and the skin mucosal surface of Atlantic salmon fry using AFM force spectroscopy. Results The results obtained revealed that when retracting probes functionalized with bacteria from surfaces coated with immobilized mucins, isolated from salmon mucosal surfaces, rupture events reflecting the disruption of adhesive interactions were observed, with rupture strengths centered around 200 pN. However, when retracting probes functionalized with bacteria from the intact mucosal surface of salmon fish fry no adhesive interactions could be detected. Furthermore, rheological measurements revealed a near fluid-like behavior for the fish fry skin mucus. Taken together, the experimental data indicate that the adhesion between the mucin molecules within the mucous layer may be significantly weaker than the interaction between the bacteria and the mucin molecules. The bacteria, immobilized on the AFM probe, do bind to individual mucins in the mucosal layer, but are released from the near fluid mucus with little resistance upon retraction of the AFM probe, to which they are immobilized. Conclusion The data provided in the current paper reveal that A. salmonicida and Y. ruckeri do bind to the immobilized mucins. However, when retracting the bacteria from intact mucosal surfaces, no adhesive interactions are detected. These observations suggest a mechanism underlying the protective function of the mucosal surface based on the clearing of potential threats by adhering them to loosely attached mucus that is subsequently released from the fish skin.

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