A boy with developmental delay, malformations, and evidence of a connective tissue disorder: possibly a new type of cutis laxa.

PubMed

Armstrong, Linlea; Jimenez, Carmencita; Hunter, Alasdair G W

2003-05-15

We report a 7.5-year-old boy with loose translucent skin, aortic dilatation, hyperextensible veins, recurrent respiratory problems, pectus excavatum, arthralgias, lax joints, mild epiphyseal dysplasia, and umbilical and inguinal hernias. He also has developmental delay, progressive bilateral sensorineural hearing loss, an unusual facial appearance, terminal digit hypoplasia with unusual radiographic changes in some of the phalanges, glandular hypospadias, shawl scrotum, and undescended testes. Biochemical investigations, including electrophoresis of Types 1 and 3 procollagens and collagens, and quantification of serum copper and ceruloplasmin, are normal. Relative to age-matched control patients the electron micrographs of the boy's dermis show elastin fibers to be decreased in number, and abnormal in appearance, with a low matrix to microfibril ratio. The organ distribution of abnormalities and the nature of the findings suggest a connective tissue disorder. We contrast and compare this boy's phenotype to those of the classic connective tissue disorders. We conclude that he has cutis laxa with features that distinguish him from previously described types of cutis laxa. Copyright 2003 Wiley-Liss, Inc.

Arrangement of Cellulose Microfibrils in Walls of Elongating Parenchyma Cells

PubMed Central

Setterfield, G.; Bayley, S. T.

1958-01-01

The arrangement of cellulose microfibrils in walls of elongating parenchyma cells of Avena coleoptiles, onion roots, and celery petioles was studied in polarizing and electron microscopes by examining whole cell walls and sections. Walls of these cells consist firstly of regions containing the primary pit fields and composed of microfibrils oriented predominantly transversely. The transverse microfibrils show a progressive disorientation from the inside to the outside of the wall which is consistent with the multinet model of wall growth. Between the pit-field regions and running the length of the cells are ribs composed of longitudinally oriented microfibrils. Two types of rib have been found at all stages of cell elongation. In some regions, the wall appears to consist entirely of longitudinal microfibrils so that the rib forms an integral part of the wall. At the edges of such ribs the microfibrils can be seen to change direction from longitudinal in the rib to transverse in the pit-field region. Often, however, the rib appears to consist of an extra separate layer of longitudinal microfibrils outside a continuous wall of transverse microfibrils. These ribs are quite distinct from secondary wall, which consists of longitudinal microfibrils deposited within the primary wall after elongation has ceased. It is evident that the arrangement of cellulose microfibrils in a primary wall can be complex and is probably an expression of specific cellular differentiation. PMID:13563544

In vitro myogenesis induced by human recombinant elastin-like proteins.

PubMed

D'Andrea, Paola; Scaini, Denis; Ulloa Severino, Luisa; Borelli, Violetta; Passamonti, Sabina; Lorenzon, Paola; Bandiera, Antonella

2015-10-01

Mammalian adult skeletal muscle has a limited ability to regenerate after injury, usage or trauma. A promising strategy for successful regenerative technology is the engineering of bio interfaces that mimic the characteristics of the extracellular matrix. Human elastin-like polypeptides (HELPs) have been synthesized as biomimetic materials that maintain some peculiar properties of the native protein. We developed a novel Human Elastin Like Polypeptide obtained by fusing the elastin-like backbone to a domain present in the α2 chain of type IV collagen, containing two RGD motives. We employed this peptide as adhesion substrate for C2C12 myoblasts and compared its effects to those induced by two other polypeptides of the HELP series. Myoblast adhered to all HELPs coatings, where they assumed morphology and cytoarchitecture that depended on the polypeptide structure. Adhesion to HELPs stimulated at a different extent cell proliferation and differentiation, the expression of Myosin Heavy Chain and the fusion of aligned fibers into multinucleated myotubes. Adhesion substrates significantly altered myotubes stiffness, measured by Atomic Force Microscopy, and differently affected the cells Ca(2+) handling capacity and the maturation of excitation-contraction coupling machinery, evaluated by Ca(2+) imaging. Overall, our findings indicate that the properties of HELP biopolymers can be exploited for dissecting the molecular connections underlying myogenic differentiation and for designing novel substrates for skeletal muscle regeneration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Scanning Electron Microscope Examination of Cotton Linters and Wood Pulp Fibers before and after Nitration and Gun Propellant Manufacture

DTIC Science & Technology

1983-03-01

both types of cellulose , the cell walls are still intact with the microfibrils showing little damage. The cellulose microfibrils consist of long chains...25 2. Model of Cellulose Microfibril ... S............. .............. .26 3. Model of Plant Cell Wall Bonding of Microfibril Bundles...molecules protrude above and below the plane of the cellulose ribbon.J’ (See Figures 2 and 3,) Bundles of these cellulose ribbons are called microfibrils

Cellulose microfibril formation within a coarse grained molecular dynamics

NASA Astrophysics Data System (ADS)

Nili, Abdolmadjid; Shklyaev, Oleg; Crespi, Vincent; Zhao, Zhen; Zhong, Linghao; CLSF Collaboration

2014-03-01

Cellulose in biomass is mostly in the form of crystalline microfibrils composed of 18 to 36 parallel chains of polymerized glucose monomers. A single chain is produced by cellular machinery (CesA) located on the preliminary cell wall membrane. Information about the nucleation stage can address important questions about intermediate region between cell wall and the fully formed crystalline microfibrils. Very little is known about the transition from isolated chains to protofibrils up to a full microfibril, in contrast to a large body of studies on both CesA and the final crystalline microfibril. In addition to major experimental challenges in studying this transient regime, the length and time scales of microfibril nucleation are inaccessible to atomistic molecular dynamics. We have developed a novel coarse grained model for cellulose microfibrils which accounts for anisotropic interchain interactions. The model allows us to study nucleation, kinetics, and growth of cellulose chains/protofibrils/microfibrils. This work is supported by the US Department of Energy, Office of Basic Energy Sciences as part of The Center for LignoCellulose Structure and Formation, an Energy Frontier Research Center.

Structure of native cellulose microfibrils, the starting point for nanocellulose manufacture

NASA Astrophysics Data System (ADS)

Jarvis, Michael C.

2017-12-01

There is an emerging consensus that higher plants synthesize cellulose microfibrils that initially comprise 18 chains. However, the mean number of chains per microfibril in situ is usually greater than 18, sometimes much greater. Microfibrils from woody tissues of conifers, grasses and dicotyledonous plants, and from organs like cotton hairs, all differ in detailed structure and mean diameter. Diameters increase further when aggregated microfibrils are isolated. Because surface chains differ, the tensile properties of the cellulose may be augmented by increasing microfibril diameter. Association of microfibrils with anionic polysaccharides in primary cell walls and mucilages leads to in vivo mechanisms of disaggregation that may be relevant to the preparation of nanofibrillar cellulose products. For the preparation of nanocrystalline celluloses, the key issue is the nature and axial spacing of disordered domains at which axial scission can be initiated. These disordered domains do not, as has often been suggested, take the form of large blocks occupying much of the length of the microfibril. They are more likely to be located at chain ends or at places where the microfibril has been mechanically damaged, but their structure and the reasons for their sensitivity to acid hydrolysis need better characterization. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

Structure of native cellulose microfibrils, the starting point for nanocellulose manufacture.

PubMed

Jarvis, Michael C

2018-02-13

There is an emerging consensus that higher plants synthesize cellulose microfibrils that initially comprise 18 chains. However, the mean number of chains per microfibril in situ is usually greater than 18, sometimes much greater. Microfibrils from woody tissues of conifers, grasses and dicotyledonous plants, and from organs like cotton hairs, all differ in detailed structure and mean diameter. Diameters increase further when aggregated microfibrils are isolated. Because surface chains differ, the tensile properties of the cellulose may be augmented by increasing microfibril diameter. Association of microfibrils with anionic polysaccharides in primary cell walls and mucilages leads to in vivo mechanisms of disaggregation that may be relevant to the preparation of nanofibrillar cellulose products. For the preparation of nanocrystalline celluloses, the key issue is the nature and axial spacing of disordered domains at which axial scission can be initiated. These disordered domains do not, as has often been suggested, take the form of large blocks occupying much of the length of the microfibril. They are more likely to be located at chain ends or at places where the microfibril has been mechanically damaged, but their structure and the reasons for their sensitivity to acid hydrolysis need better characterization.This article is part of a discussion meeting issue 'New horizons for cellulose nanotechnology'. © 2017 The Author(s).

Cell wall biogenesis in Oocystis: experimental alteration of microfibril assembly and orientation.

PubMed

Montezinos, D; Brown, R M

1978-01-01

Cell wall biogenesis in the unicellular green alga Oocystis apiculata has been studied. Under normal growth conditions, a cell wall with ordered microfibrils is synthesized. In each layer there are rows of parallel microfibrils. Layers are nearly perpendicular to each other. Terminal linear synthesizing complexes are located in the plasma membrane, and they are capable of bidirectional synthesis of cellulose microfibrils. Granule bands associated with the inner leaflet of the plasma membrane appear to control the orientation of newly synthesized microfibrils. Subcortical microtubules also are present during wall synthesis. Patterns of cell wall synthesis were studied after treatment with EDTA and EGTA as well as divalent cations (MgSO4, CaSO4, Cacl2). 0.1 M EDTA treatment for 15 min results in the disassociation of the terminal complexes from the ends of microfibrils. EDTA-treated cells followed by 15 min treatment with MgSO4 results in reaggregation of the linear complexes into a paired state, remote from the original ends to which they were associated. After 90 min treatment with MgSO4, normal synthesis resumes. EGTA and calcium salts do not affect the linear complexes or microfibril orientation. Treatments with colchicine and vinblastine sulphate do not depolymerize the microtubles, but the wall microfibril orientation is altered. With colchicine or vinblastine, the change in orientation from layer to layer is inhibited. The process is reversible upon removal of the drugs. Lumicolchicine has no effect upon microfibril orientation, but granule bands are disorganized. Treatment with coumarin, a known inhibitor of cellulose synthesis, causes the loss of visualization of subunits of the terminal complexes. The possibility of the existence of a membrane-associated colchicine-sensitive orientation protein for cellulose microfibrils is discussed. Transmembrane modulation of microfibril synthesis and orientation is presented.

Within tree variation of lignin, extractives, and microfibril angle coupled with the theoretical and near infrared modeling of microfibril angle

Treesearch

Brian K. Via; chi L. So; Leslie H. Groom; Todd F. Shupe; michael Stine; Jan Wikaira

2007-01-01

A theoretical model was built predicting the relationship between microfibril angle and lignin content at the Angstrom (A) level. Both theoretical and statistical examination of experimental data supports a square root transformation of lignin to predict microfibril angle. The experimental material used came from 10 longleaf pine (Pinus palustris)...

Chemical genetic screening identifies a novel inhibitor of parallel alignment of cortical microtubules and cellulose microfibrils.

PubMed

Yoneda, Arata; Higaki, Takumi; Kutsuna, Natsumaro; Kondo, Yoichi; Osada, Hiroyuki; Hasezawa, Seiichiro; Matsui, Minami

2007-10-01

It is a well-known hypothesis that cortical microtubules control the direction of cellulose microfibril deposition, and that the parallel cellulose microfibrils determine anisotropic cell expansion and plant cell morphogenesis. However, the molecular mechanism by which cortical microtubules regulate the orientation of cellulose microfibrils is still unclear. To investigate this mechanism, chemical genetic screening was performed. From this screening, 'SS compounds' were identified that induced a spherical swelling phenotype in tobacco BY-2 cells. The SS compounds could be categorized into three classes: those that disrupted the cortical microtubules; those that reduced cellulose microfibril content; and thirdly those that had neither of these effects. In the last class, a chemical designated 'cobtorin' was found to induce the spherical swelling phenotype at the lowest concentration, suggesting strong binding activity to the putative target. Examining cellulose microfibril regeneration using taxol-treated protoplasts revealed that the cobtorin compound perturbed the parallel alignment of pre-existing cortical microtubules and nascent cellulose microfibrils. Thus, cobtorin could be a novel inhibitor and an attractive tool for further investigation of the mechanism that enables cortical microtubules to guide the parallel deposition of cellulose microfibrils.

CNGA3 is expressed in inner ear hair cells and binds to an intracellular C-terminus domain of EMILIN1.

PubMed

Selvakumar, Dakshnamurthy; Drescher, Marian J; Dowdall, Jayme R; Khan, Khalid M; Hatfield, James S; Ramakrishnan, Neeliyath A; Drescher, Dennis G

2012-04-15

The molecular characteristics of CNG (cyclic nucleotide-gated) channels in auditory/vestibular hair cells are largely unknown, unlike those of CNG mediating sensory transduction in vision and olfaction. In the present study we report the full-length sequence for three CNGA3 variants in a hair cell preparation from the trout saccule with high identity to CNGA3 in olfactory receptor neurons/cone photoreceptors. A custom antibody targeting the N-terminal sequence immunolocalized CNGA3 to the stereocilia and subcuticular plate region of saccular hair cells. The cytoplasmic C-terminus of CNGA3 was found by yeast two-hybrid analysis to bind the C-terminus of EMILIN1 (elastin microfibril interface-located protein 1) in both the vestibular hair cell model and rat organ of Corti. Specific binding between CNGA3 and EMILIN1 was confirmed with surface plasmon resonance analysis, predicting dependence on Ca2+ with Kd=1.6×10-6 M for trout hair cell proteins and Kd=2.7×10-7 M for organ of Corti proteins at 68 μM Ca2+. Pull-down assays indicated that the binding to organ of Corti CNGA3 was attributable to the EMILIN1 intracellular sequence that follows a predicted transmembrane domain in the C-terminus. Saccular hair cells also express the transcript for PDE6C (phosphodiesterase 6C), which in cone photoreceptors regulates the degradation of cGMP used to gate CNGA3 in phototransduction. Taken together, the evidence supports the existence in saccular hair cells of a molecular pathway linking CNGA3, its binding partner EMILIN1 (and β1 integrin) and cGMP-specific PDE6C, which is potentially replicated in cochlear outer hair cells, given stereociliary immunolocalizations of CNGA3, EMILIN1 and PDE6C.

The solvation structures of cellulose microfibrils in ionic liquids.

PubMed

Mostofian, Barmak; Smith, Jeremy C; Cheng, Xiaolin

2011-12-01

The use of ionic liquids for non-derivatized cellulose dissolution promises an alternative method for the thermochemical pretreatment of biomass that may be more efficient and environmentally acceptable than more conventional techniques in aqueous solution. Here, we performed equilibrium MD simulations of a cellulose microfibril in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and compared the solute structure and the solute-solvent interactions at the interface with those from corresponding simulations in water. The results indicate a higher occurrence of solvent-exposed orientations of cellulose surface hydroxymethyl groups in BmimCl than in water. Moreover, spatial and radial distribution functions indicate that hydrophilic surfaces are a preferred site of interaction between cellulose and the ionic liquid. In particular, hydroxymethyl groups on the hydrophilic fiber surface adopt a different conformation from their counterparts oriented towards the fiber's core. Furthermore, the glucose units with these solvent-oriented hydroxymethyls are surrounded by the heterocyclic organic cation in a preferred parallel orientation, suggesting a direct and distinct interaction scheme between cellulose and BmimCl.

Stress transfer and matrix-cohesive fracture mechanism in microfibrillated cellulose-gelatin nanocomposite films.

PubMed

Quero, Franck; Padilla, Cristina; Campos, Vanessa; Luengo, Jorge; Caballero, Leonardo; Melo, Francisco; Li, Qiang; Eichhorn, Stephen J; Enrione, Javier

2018-09-01

Microfibrillated cellulose (MFC) obtained from eucalyptus was embedded in gelatin from two sources; namely bovine and salmon gelatin. Raman spectroscopy revealed that stress is transferred more efficiently from bovine gelatin to the MFC when compared to salmon gelatin. Young's modulus, tensile strength, strain at failure and work of fracture of the nanocomposite films were improved by ∼67, 131, 43 y 243% respectively when using salmon gelatin as matrix material instead of bovine gelatin. Imaging of the tensile fracture surface of the MFC-gelatin nanocomposites revealed that crack formation occurs predominantly within bovine and salmon gelatin matrices rather than within the MFC or at the MFC/gelatin interface. This suggests that the mechanical failure mechanism in these nanocomposite materials is predominantly governed by a matrix-cohesive fracture mechanism. Both strength and flexibility are desirable properties for composite coatings made from gelatin-based materials, and so the findings of this study could assist in their utilization in the food and pharmaceutical industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Elastin hydrolysate derived from fish enhances proliferation of human skin fibroblasts and elastin synthesis in human skin fibroblasts and improves the skin conditions.

PubMed

Shiratsuchi, Eri; Nakaba, Misako; Yamada, Michio

2016-03-30

Recent studies have shown that certain peptides significantly improve skin conditions, such as skin elasticity and the moisture content of the skin of healthy woman. This study aimed to investigate the effects of elastin hydrolysate on human skin. Proliferation and elastin synthesis were evaluated in human skin fibroblasts exposed to elastin hydrolysate and proryl-glycine (Pro-Gly), which is present in human blood after elastin hydrolysate ingestion. We also performed an ingestion test with elastin hydrolysate in humans and evaluated skin condition. Elastin hydrolysate and Pro-Gly enhanced the proliferation of fibroblasts and elastin synthesis. Maximal proliferation response was observed at 25 ng mL(-1) Pro-Gly. Ingestion of elastin hydrolysate improved skin condition, such as elasticity, number of wrinkles, and blood flow. Elasticity improved by 4% in the elastin hydrolysate group compared with 2% in the placebo group. Therefore, elastin hydrolysate activates human skin fibroblasts and has beneficial effects on skin conditions. © 2015 Society of Chemical Industry.

Alteration of Oriented Deposition of Cellulose Microfibrils by Mutation of a Katanin-Like Microtubule-Severing Protein

PubMed Central

Burk, David H.; Ye, Zheng-Hua

2002-01-01

It has long been hypothesized that cortical microtubules (MTs) control the orientation of cellulose microfibril deposition, but no mutants with alterations of MT orientation have been shown to affect this process. We have shown previously that in Arabidopsis, the fra2 mutation causes aberrant cortical MT orientation and reduced cell elongation, and the gene responsible for the fra2 mutation encodes a katanin-like protein. In this study, using field emission scanning electron microscopy, we found that the fra2 mutation altered the normal orientation of cellulose microfibrils in walls of expanding cells. Although cellulose microfibrils in walls of wild-type cells were oriented transversely along the elongation axis, cellulose microfibrils in walls of fra2 cells often formed bands and ran in different directions. The fra2 mutation also caused aberrant deposition of cellulose microfibrils in secondary walls of fiber cells. The aberrant orientation of cellulose microfibrils was shown to be correlated with disorganized cortical MTs in several cell types examined. In addition, the thickness of both primary and secondary cell walls was reduced significantly in the fra2 mutant. These results indicate that the katanin-like protein is essential for oriented cellulose microfibril deposition and normal cell wall biosynthesis. We further demonstrated that the Arabidopsis katanin-like protein possessed MT-severing activity in vitro; thus, it is an ortholog of animal katanin. We propose that the aberrant MT orientation caused by the mutation of katanin results in the distorted deposition of cellulose microfibrils, which in turn leads to a defect in cell elongation. These findings strongly support the hypothesis that cortical MTs regulate the oriented deposition of cellulose microfibrils that determines the direction of cell elongation. PMID:12215512

Alteration of oriented deposition of cellulose microfibrils by mutation of a katanin-like microtubule-severing protein.

PubMed

Burk, David H; Ye, Zheng-Hua

2002-09-01

It has long been hypothesized that cortical microtubules (MTs) control the orientation of cellulose microfibril deposition, but no mutants with alterations of MT orientation have been shown to affect this process. We have shown previously that in Arabidopsis, the fra2 mutation causes aberrant cortical MT orientation and reduced cell elongation, and the gene responsible for the fra2 mutation encodes a katanin-like protein. In this study, using field emission scanning electron microscopy, we found that the fra2 mutation altered the normal orientation of cellulose microfibrils in walls of expanding cells. Although cellulose microfibrils in walls of wild-type cells were oriented transversely along the elongation axis, cellulose microfibrils in walls of fra2 cells often formed bands and ran in different directions. The fra2 mutation also caused aberrant deposition of cellulose microfibrils in secondary walls of fiber cells. The aberrant orientation of cellulose microfibrils was shown to be correlated with disorganized cortical MTs in several cell types examined. In addition, the thickness of both primary and secondary cell walls was reduced significantly in the fra2 mutant. These results indicate that the katanin-like protein is essential for oriented cellulose microfibril deposition and normal cell wall biosynthesis. We further demonstrated that the Arabidopsis katanin-like protein possessed MT-severing activity in vitro; thus, it is an ortholog of animal katanin. We propose that the aberrant MT orientation caused by the mutation of katanin results in the distorted deposition of cellulose microfibrils, which in turn leads to a defect in cell elongation. These findings strongly support the hypothesis that cortical MTs regulate the oriented deposition of cellulose microfibrils that determines the direction of cell elongation.

Serological assessment of neutrophil elastase activity on elastin during lung ECM remodeling.

PubMed

Kristensen, Jacob H; Karsdal, Morten A; Sand, Jannie Mb; Willumsen, Nicholas; Diefenbach, Claudia; Svensson, Birte; Hägglund, Per; Oersnes-Leeming, Diana J

2015-05-03

During the pathological destruction of lung tissue, neutrophil elastase (NE) degrades elastin, one of the major constituents of lung parenchyma. However there are no non-invasive methods to quantify NE degradation of elastin. We selected specific elastin fragments generated by NE for antibody generation and developed an ELISA assay (EL-NE) for the quantification of NE-degraded elastin. Monoclonal antibodies were developed against 10 NE-specific cleavage sites on elastin. One EL-NE assay was tested for analyte stability, linearity and intra- and inter-assay variation. The NE specificity was demonstrated using elastin cleaved in vitro with matrix metalloproteinases (MMPs), cathepsin G (CatG), NE and intact elastin. Clinical relevance was assessed by measuring levels of NE-generated elastin fragments in serum of patients diagnosed with idiopathic pulmonary fibrosis (IPF, n = 10) or lung cancer (n = 40). Analyte recovery of EL-NE for human serum was between 85% and 104%, the analyte was stable for four freeze/thaw cycles and after 24 h storage at 4°C. EL-NE was specific for NE-degraded elastin. Levels of NE-generated elastin fragments for elastin incubated in the presence of NE were 900% to 4700% higher than those seen with CatG or MMP incubation or in intact elastin. Serum levels of NE-generated elastin fragments were significantly increased in patients with IPF (137%, p = 0.002) and in patients with lung cancer (510%, p < 0.001) compared with age- and sex-matched controls. The EL-NE assay was specific for NE-degraded elastin. The EL-NE assay was able to specifically quantify NE-degraded elastin in serum. Serum levels of NE-degraded elastin might be used to detect excessive lung tissue degradation in lung cancer and IPF.

The development of a novel wound healing material, silk-elastin sponge.

PubMed

Kawabata, Shingo; Kawai, Katsuya; Somamoto, Satoshi; Noda, Kazuo; Matsuura, Yoshitaka; Nakamura, Yoko; Suzuki, Shigehiko

2017-12-01

Silk-elastin is a recombinant protein polymer with repeating units of silk and elastin blocks. This novel wound healing promoting material has the ability to self-assemble from a liquid to a gel. We have already reported that an aqueous solution of silk-elastin has the potential to accelerate wound healing; however, there are several problems in applying silk-elastin in the clinical setting. To solve these problems, we developed a silk-elastin sponge that is easy to use in the clinical setting. In the present study, we examined whether the wound healing effect of the silk-elastin sponge is equal to the aqueous solution of silk-elastin in vivo. The granulation tissue formation promoting effect of the silk-elastin sponge was equal to that of the aqueous solution the silk-elastin, as after application to the wound surface, the sponge was absorbed and dissolved by the exudate. At body temperature the silk-elastin then formed temperature gel. The silk-elastin gel that was obtained contained abundant cytokines from the exudate. We believe that silk-elastin sponge can be applied to various wounds that are difficult to treat with the aqueous solution.

Epithelial-mesenchymal status influences how cells deposit fibrillin microfibrils.

PubMed

Baldwin, Andrew K; Cain, Stuart A; Lennon, Rachel; Godwin, Alan; Merry, Catherine L R; Kielty, Cay M

2014-01-01

Here, we show that epithelial-mesenchymal status influences how cells deposit extracellular matrix. Retinal pigmented epithelial (RPE) cells that expressed high levels of E-cadherin and had cell-cell junctions rich in zona occludens (ZO)-1, β-catenin and heparan sulfate, required syndecan-4 but not fibronectin or protein kinase C α (PKCα) to assemble extracellular matrix (fibrillin microfibrils and perlecan). In contrast, RPE cells that strongly expressed mesenchymal smooth muscle α-actin but little ZO-1 or E-cadherin, required fibronectin (like fibroblasts) and PKCα, but not syndecan-4. Integrins α5β1 and/or α8β1 and actomyosin tension were common requirements for microfibril deposition, as was heparan sulfate biosynthesis. TGFβ, which stimulates epithelial-mesenchymal transition, altered gene expression and overcame the dependency on syndecan-4 for microfibril deposition in epithelial RPE cells, whereas blocking cadherin interactions disrupted microfibril deposition. Renal podocytes had a transitional phenotype with pericellular β-catenin but little ZO-1; they required syndecan-4 and fibronectin for efficient microfibril deposition. Thus, epithelial-mesenchymal status modulates microfibril deposition.

Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

PubMed

De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

2010-08-01

During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.

Cellulose microfibrils in plants: biosynthesis, deposition, and integration into the cell wall.

PubMed

Brett, C T

2000-01-01

Cellulose occurs in all higher plants and some algae, fungi, bacteria, and animals. It forms microfibrils containing the crystalline allomorphs, cellulose I alpha and I beta. Cellulose molecules are 500-15,000 glucose units long. What controls molecular size is unknown. Microfibrils are elongated by particle rosettes in the plasma membrane (cellulose synthase complexes). The precursor, UDP-glucose, may be generated from sucrose at the site of synthesis. The biosynthetic mechanism may involve lipid-linked intermediates. Cellulose synthase has been purified from bacteria, but not from plants. In plants, disrupted cellulose synthase may form callose. Cellulose synthase genes have been isolated from bacteria and plants. Cellulose-deficient mutants have been characterised. The deduced amino acid sequence suggests possible catalytic mechanisms. It is not known whether synthesis occurs at the reducing or nonreducing end. Endoglucanase may play a role in synthesis. Nascent cellulose molecules associate by Van der Waals and hydrogen bonds to form microfibrils. Cortical microtubules control microfibril orientation, thus determining the direction of cell growth. Self-assembly mechanisms may operate. Microfibril integration into the wall occurs by interactions with matrix polymers during microfibril formation.

Concerns about a variance approach to the X-ray diffractometric estimation of microfibril angle in wood

Treesearch

Steve P. Verrill; David E. Kretschmann; Victoria L. Herian; Michael Wiemann; Harry A. Alden

2010-01-01

In this paper we raise three technical concerns about Evans’s 1999 Appita Journal “variance approach” to estimating microfibril angle. The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the microfibril angle and the natural variability of the microfibril angle, S2...

Microfibril-associated glycoproteins MAGP-1 and MAGP-2 in disease.

PubMed

Craft, Clarissa S; Broekelmann, Thomas J; Mecham, Robert P

2018-03-07

Microfibril-associated glycoproteins 1 and 2 (MAGP-1, MAGP-2) are protein components of extracellular matrix microfibrils. These proteins interact with fibrillin, the core component of microfibrils, and impart unique biological properties that influence microfibril function in vertebrates. MAGPs bind active forms of TGFβ and BMPs and are capable of modulating Notch signaling. Mutations in MAGP-1 or MAGP-2 have been linked to thoracic aneurysms and metabolic disease in humans. MAGP-2 has also been shown to be an important biomarker in several human cancers. Mice lacking MAGP-1 or MAGP-2 have defects in multiple organ systems, which reflects the widespread distribution of microfibrils in vertebrate tissues. This review summarizes our current understanding of the function of the MAGPs and their relationship to human disease. Copyright © 2017 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

Nanostructure of cellulose microfibrils in spruce wood.

PubMed

Fernandes, Anwesha N; Thomas, Lynne H; Altaner, Clemens M; Callow, Philip; Forsyth, V Trevor; Apperley, David C; Kennedy, Craig J; Jarvis, Michael C

2011-11-22

The structure of cellulose microfibrils in wood is not known in detail, despite the abundance of cellulose in woody biomass and its importance for biology, energy, and engineering. The structure of the microfibrils of spruce wood cellulose was investigated using a range of spectroscopic methods coupled to small-angle neutron and wide-angle X-ray scattering. The scattering data were consistent with 24-chain microfibrils and favored a "rectangular" model with both hydrophobic and hydrophilic surfaces exposed. Disorder in chain packing and hydrogen bonding was shown to increase outwards from the microfibril center. The extent of disorder blurred the distinction between the I alpha and I beta allomorphs. Chains at the surface were distinct in conformation, with high levels of conformational disorder at C-6, less intramolecular hydrogen bonding and more outward-directed hydrogen bonding. Axial disorder could be explained in terms of twisting of the microfibrils, with implications for their biosynthesis.

Procyanidins-crosslinked aortic elastin scaffolds with distinctive anti-calcification and biological properties.

PubMed

Wang, Xiaoya; Zhai, Wanyin; Wu, Chengtie; Ma, Bing; Zhang, Jiamin; Zhang, Hongfeng; Zhu, Ziyan; Chang, Jiang

2015-04-01

Elastin, a main component of decellularized extracellular matrices and elastin-containing materials, has been used for tissue engineering applications due to their excellent biocompatibility. However, elastin is easily calcified, leading to the decrease of life span for elastin-based substitutes. How to inhibit the calcification of elastin-based scaffolds, but maintain their good biocompatibility, still remains significantly challenging. Procyanidins (PC) are a type of natural polyphenols with crosslinking ability. To investigate whether pure elastin could be crosslinked by PC with anti-calcification effect, PC was first used to crosslink aortic elastin. Results show that PC can crosslink elastin and effectively inhibit elastin-initiated calcification. Further experiments reveal the possible mechanisms for the anti-calcification of PC crosslinking including (1) inhibiting inflammation cell attachment, and secretion of inflammatory factors such as MMPs and TNF-α, (2) preventing elastin degradation by elastase, and (3) direct inhibition of mineral nucleation in elastin. Moreover, the PC-crosslinked aortic elastin maintains natural structure with high pore volume (1111 μL/g), large pore size (10-300 μm) and high porosity (75.1%) which facilitates recellularization of scaffolds in vivo, and displays excellent hemocompatibility, anti-thrombus and anti-inflammatory potential. The advantages of PC-crosslinked porous aortic elastin suggested that it can serve as a promising scaffold for tissue engineering. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Impact of Microfibril Orientations on the Biomechanics of Plant Cell Walls and Tissues.

PubMed

Ptashnyk, Mariya; Seguin, Brian

2016-11-01

The microscopic structure and anisotropy of plant cell walls greatly influence the mechanical properties, morphogenesis, and growth of plant cells and tissues. The microscopic structure and properties of cell walls are determined by the orientation and mechanical properties of the cellulose microfibrils and the mechanical properties of the cell wall matrix. Viewing the shape of a plant cell as a square prism with the axis aligning with the primary direction of expansion and growth, the orientation of the microfibrils within the side walls, i.e. the parts of the cell walls on the sides of the cells, is known. However, not much is known about their orientation at the upper and lower ends of the cell. Here we investigate the impact of the orientation of cellulose microfibrils within the upper and lower parts of the plant cell walls by solving the equations of linear elasticity numerically. Three different scenarios for the orientation of the microfibrils are considered. We also distinguish between the microstructure in the side walls given by microfibrils perpendicular to the main direction of the expansion and the situation where the microfibrils are rotated through the wall thickness. The macroscopic elastic properties of the cell wall are obtained using homogenization theory from the microscopic description of the elastic properties of the cell wall microfibrils and wall matrix. It is found that the orientation of the microfibrils in the upper and lower parts of the cell walls affects the expansion of the cell in the lateral directions and is particularly important in the case of forces acting on plant cell walls and tissues.

Liberation of Desmosine and Isodesmosine as Amino Acids from Insoluble Elastin by Elastolytic Proteases

PubMed Central

Umeda, Hideyuki; Aikawa, Masanori; Libby, Peter

2011-01-01

The development of atherosclerotic lesions and abdominal aortic aneurysms involves degradation and loss of extracellular matrix components, such as collagen and elastin. Releases of the elastin cross-links desmosine (DES) and isodesmosine (IDE) may reflect elastin degradation in cardiovascular diseases. This study investigated the production of soluble elastin cross-linking structures by proteinases implicated in arterial diseases. Recombinant MMP-12 and neutrophil elastase liberated DES and IDE as amino acids from insoluble elastin. DES and IDE were also released from insoluble elastin exposed to monocyte/macrophage cell lines or human primary macrophages derived from peripheral blood monocytes. Elastin oxidized by reactive oxygen species (ROS) liberated more unconjugated DES and IDE than did non-oxidized elastin when incubated with MMP-12 or neutrophil elastase. These results support the exploration of free DES and IDE as biomarkers of elastin degradation. PMID:21726534

Structure of Cellulose Microfibrils in Primary Cell Walls from Collenchyma1[C][W][OA

PubMed Central

Thomas, Lynne H.; Forsyth, V. Trevor; Šturcová, Adriana; Kennedy, Craig J.; May, Roland P.; Altaner, Clemens M.; Apperley, David C.; Wess, Timothy J.; Jarvis, Michael C.

2013-01-01

In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production. PMID:23175754

Structure of cellulose microfibrils in primary cell walls from collenchyma.

PubMed

Thomas, Lynne H; Forsyth, V Trevor; Sturcová, Adriana; Kennedy, Craig J; May, Roland P; Altaner, Clemens M; Apperley, David C; Wess, Timothy J; Jarvis, Michael C

2013-01-01

In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion; therefore, cellulose synthesis is a key factor in the growth and morphogenesis of plants. Celery (Apium graveolens) collenchyma is a useful model system for the study of primary wall microfibril structure because its microfibrils are oriented with unusual uniformity, facilitating spectroscopic and diffraction experiments. Using a combination of x-ray and neutron scattering methods with vibrational and nuclear magnetic resonance spectroscopy, we show that celery collenchyma microfibrils were 2.9 to 3.0 nm in mean diameter, with a most probable structure containing 24 chains in cross section, arranged in eight hydrogen-bonded sheets of three chains, with extensive disorder in lateral packing, conformation, and hydrogen bonding. A similar 18-chain structure, and 24-chain structures of different shape, fitted the data less well. Conformational disorder was largely restricted to the surface chains, but disorder in chain packing was not. That is, in position and orientation, the surface chains conformed to the disordered lattice constituting the core of each microfibril. There was evidence that adjacent microfibrils were noncovalently aggregated together over part of their length, suggesting that the need to disrupt these aggregates might be a constraining factor in growth and in the hydrolysis of cellulose for biofuel production.

Soluble elastin peptides in cardiovascular homeostasis: Foe or ally.

PubMed

Qin, Zhenyu

2015-05-01

Elastin peptides, also known as elastin-derived peptides or elastokines, are soluble polypeptides in blood and tissue. The blood levels of elastin peptides are usually low but can increase during cardiovascular diseases, such as atherosclerosis, aortic aneurysm and diabetes with vascular complications. Generally, elastin peptides are derived from the degradation of insoluble elastic polymers. The biological activities of elastin peptides are bidirectional, e.g., a pro-inflammatory effect on monocyte migration induction vs. a protective effect on vasodilation promotion. However, recent in vivo studies have demonstrated that elastin peptides promote the formation of atherosclerotic plaques in hypercholesterolemic mice and induce hyperglycemia and elevations in plasma lipid levels in fasted mice. More important, the detrimental effects induced by elastin peptides can be largely inhibited by genetic or pharmacological blockade of the elastin receptor complex or by neutralization of an antibody against elastin peptides. These studies indicate new therapeutic strategies for the treatment of cardiovascular diseases by targeting elastin peptide metabolism. Therefore, the goal of this review is to summarize current knowledge about elastin peptides relevant to cardiovascular pathologies to further delineate their potential application in cardiovascular disease. Copyright © 2015 Elsevier Inc. All rights reserved.

Contribution of elastin and collagen to the inflation response of the pig thoracic aorta: assessing elastin's role in mechanical homeostasis.

PubMed

Lillie, M A; Armstrong, T E; Gérard, S G; Shadwick, R E; Gosline, J M

2012-08-09

This study was undertaken to understand elastin's role in the mechanical homeostasis of the arterial wall. The mechanical properties of elastin vary along the aorta, and we hypothesized this maintained a uniform mechanical environment for the elastin, despite regional variation in loading. Elastin's physiological loading was determined by comparing the inflation response of intact and autoclave purified elastin aortas from the proximal and distal thoracic aorta. Elastin's stretch and stress depend on collagen recruitment. Collagen recruitment started in the proximal aorta at systolic pressures (13.3 to 14.6 kPa) and in the distal at sub-diastolic pressures (9.3 to 10.6 kPa). In the proximal aorta collagen did not contribute significantly to the stress or stiffness, indicating that elastin determined the vessel properties. In the distal aorta, the circumferential incremental modulus was 70% higher than in the proximal aorta, half of which (37%) was due to a stiffening of the elastin. Compared to the elastin tissue in the proximal aorta, the distal elastin suffered higher physiological circumferential stretch (29%, P=0.03), circumferential stress (39%, P=0.02), and circumferential stiffness (37%, P=0.006). Elastin's physiological axial stresses were also higher (67%, P=0.003). These findings do not support the hypothesis that the loading on elastin is constant along the aorta as we expected from homeostasis. Copyright © 2012 Elsevier Ltd. All rights reserved.

Preparation and properties of self-reinforced cellulose composite films from Agave microfibrils using an ionic liquid.

PubMed

Reddy, K Obi; Zhang, Jinming; Zhang, Jun; Rajulu, A Varada

2014-12-19

The applications of natural fibers and their microfibrils are increasing rapidly due to their environment benefits, specific strength properties and renewability. In the present work, we successfully extracted cellulose microfibrils from Agave natural fibers by chemical method. The extracted microfibrils were characterized by chemical analysis. The cellulose microfibrils were found to dissolve in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) to larger extent along with little quantity of undissolved microfibrils. Using this solution, the self-reinforced regenerated cellulose composite films were prepared. The raw fiber, extracted cellulose microfibrils and regenerated cellulose composite films were characterized by FTIR, (13)C CP-MAS NMR, XRD, TGA and SEM techniques. The average tensile strength, modulus and elongation at break of the self-reinforced cellulose composite films were found to be 135 MPa, 8150 MPa and 3.2%, respectively. The high values of tensile strength and modulus were attributed to the self-reinforcement of Agave fibers in their generated matrix. These self-reinforced cellulose biodegradable composite films prepared from renewable source can find applications in packaging field. Copyright © 2014 Elsevier Ltd. All rights reserved.

New techniques enable comparative analysis of microtubule orientation, wall texture, and growth rate in intact roots of Arabidopsis.

PubMed

Sugimoto, K; Williamson, R E; Wasteneys, G O

2000-12-01

This article explores root epidermal cell elongation and its dependence on two structural elements of cells, cortical microtubules and cellulose microfibrils. The recent identification of Arabidopsis morphology mutants with putative cell wall or cytoskeletal defects demands a procedure for examining and comparing wall architecture and microtubule organization patterns in this species. We developed methods to examine cellulose microfibrils by field emission scanning electron microscopy and microtubules by immunofluorescence in essentially intact roots. We were able to compare cellulose microfibril and microtubule alignment patterns at equivalent stages of cell expansion. Field emission scanning electron microscopy revealed that Arabidopsis root epidermal cells have typical dicot primary cell wall structure with prominent transverse cellulose microfibrils embedded in pectic substances. Our analysis showed that microtubules and microfibrils have similar orientation only during the initial phase of elongation growth. Microtubule patterns deviate from a predominantly transverse orientation while cells are still expanding, whereas cellulose microfibrils remain transverse until well after expansion finishes. We also observed microtubule-microfibril alignment discord before cells enter their elongation phase. This study and the new technology it presents provide a starting point for further investigations on the physical properties of cell walls and their mechanisms of assembly.

Preparation of sago starch-based biocomposite reinforced microfibrillated cellulose of bamboo assisted by mechanical treatment

NASA Astrophysics Data System (ADS)

Silviana, S.; Hadiyanto, H.

2017-06-01

The utilization of green composites by using natural fibres is developed due to their availability, ecological benefits, and good properties in mechanical and thermal. One of the potential sources is bamboo that has relative high cellulose content. This paper was focused on the preparation of sago starch-based reinforced microfribrillated cellulose of bamboo that was assisted by mechanical treatment. Microfibrillated cellulose of bamboo was prepared by isolation of cellulose with chemical treatment. Preparation of bamboo microfibrillated cellulose was conducted by homogenizers for dispersing bamboo cellulose, i.e. high pressure homogenizer and ultrasonic homogenizer. Experiments were elaborated on several variables such as the concentration of bamboo microfibrillated cellulose dispersed in water (1-3 %w) and the volume of microfibrillated cellulose (37.5-75%v). Four %w of sago starch solution was mixed with bamboo microfibrillated cellulose and glycerol with plasticizer and citric acid as cross linker. This paper provided the analysis of tensile strength as well as SEM for mechanical and morphology properties of the biocomposite. The results showed that the preparation of sago starch-based biocomposite reinforced bamboo microfibrillated cellulose by using ultrasonic homogenizer yielded the highest tensile strength and well dispersed in the biocomposite.

Microtubules and cellulose biosynthesis: the emergence of new players.

PubMed

Li, Shundai; Lei, Lei; Yingling, Yaroslava G; Gu, Ying

2015-12-01

Microtubules determine the orientation of newly formed cellulose microfibrils in expanding cells. There are many hypotheses regarding how the information is transduced across the plasma membrane from microtubules to cellulose microfibrils. However, the molecular mechanisms underlying the co-alignment between microtubules and cellulose microfibrils were not revealed until the recent discovery of cellulose synthase interacting (CSI) proteins. Characterization of CSIs and additional cellulose synthase-associated proteins will greatly advance the knowledge of how cellulose microfibrils are organized. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cellulose microfibrils: visualization of biosynthetic and orienting complexes in association with the plasma membrane.

PubMed

Brown, R M; Montezinos, D

1976-01-01

Cellulose microfibril biosynthesis, assembly, and orientation in the unicellular green alga, Oocystis, is visualized in association with a linear enzyme complex embedded in the B face of the plasma membrane. Granule bands of the A face and complementary ridges of the B face are postulated to assist in the orientation of recently synthesized microfibrils. A model for microfibril synthesis and orientation is proposed and correlated with current hypotheses regarding cellulose biosynthesis in higher plants.

Diffraction evidence for the structure of cellulose microfibrils in bamboo, a model for grass and cereal celluloses.

PubMed

Thomas, Lynne H; Forsyth, V Trevor; Martel, Anne; Grillo, Isabelle; Altaner, Clemens M; Jarvis, Michael C

2015-06-23

Cellulose from grasses and cereals makes up much of the potential raw material for biofuel production. It is not clear if cellulose microfibrils from grasses and cereals differ in structure from those of other plants. The structures of the highly oriented cellulose microfibrils in the cell walls of the internodes of the bamboo Pseudosasa amabilis are reported. Strong orientation facilitated the use of a range of scattering techniques. Small-angle neutron scattering provided evidence of extensive aggregation by hydrogen bonding through the hydrophilic edges of the sheets of chains. The microfibrils had a mean centre-to-centre distance of 3.0 nm in the dry state, expanding on hydration. The expansion on hydration suggests that this distance between centres was through the hydrophilic faces of adjacent microfibrils. However in the other direction, perpendicular to the sheets of chains, the mean, disorder-corrected Scherrer dimension from wide-angle X-ray scattering was 3.8 nm. It is possible that this dimension is increased by twinning (crystallographic coalescence) of thinner microfibrils over part of their length, through the hydrophobic faces. The wide-angle scattering data also showed that the microfibrils had a relatively large intersheet d-spacing and small monoclinic angle, features normally considered characteristic of primary-wall cellulose. Bamboo microfibrils have features found in both primary-wall and secondary-wall cellulose, but are crystallographically coalescent to a greater extent than is common in celluloses from other plants. The extensive aggregation and local coalescence of the microfibrils are likely to have parallels in other grass and cereal species and to influence the accessibility of cellulose to degradative enzymes during conversion to liquid biofuels.

Spatial organization of cellulose microfibrils and matrix polysaccharides in primary plant cell walls as imaged by multichannel atomic force microscopy.

PubMed

Zhang, Tian; Zheng, Yunzhen; Cosgrove, Daniel J

2016-01-01

We used atomic force microscopy (AFM), complemented with electron microscopy, to characterize the nanoscale and mesoscale structure of the outer (periclinal) cell wall of onion scale epidermis - a model system for relating wall structure to cell wall mechanics. The epidermal wall contains ~100 lamellae, each ~40 nm thick, containing 3.5-nm wide cellulose microfibrils oriented in a common direction within a lamella but varying by ~30 to 90° between adjacent lamellae. The wall thus has a crossed polylamellate, not helicoidal, wall structure. Montages of high-resolution AFM images of the newly deposited wall surface showed that single microfibrils merge into and out of short regions of microfibril bundles, thereby forming a reticulated network. Microfibril direction within a lamella did not change gradually or abruptly across the whole face of the cell, indicating continuity of the lamella across the outer wall. A layer of pectin at the wall surface obscured the underlying cellulose microfibrils when imaged by FESEM, but not by AFM. The AFM thus preferentially detects cellulose microfibrils by probing through the soft matrix in these hydrated walls. AFM-based nanomechanical maps revealed significant heterogeneity in cell wall stiffness and adhesiveness at the nm scale. By color coding and merging these maps, the spatial distribution of soft and rigid matrix polymers could be visualized in the context of the stiffer microfibrils. Without chemical extraction and dehydration, our results provide multiscale structural details of the primary cell wall in its near-native state, with implications for microfibrils motions in different lamellae during uniaxial and biaxial extensions. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Temperature-sensitive elastin-mimetic dendrimers: Effect of peptide length and dendrimer generation to temperature sensitivity.

PubMed

Kojima, Chie; Irie, Kotaro; Tada, Tomoko; Tanaka, Naoki

2014-06-01

Dendrimers are synthetic macromolecules with unique structure, which are a potential scaffold for peptides. Elastin is one of the main components of extracellular matrix and a temperature-sensitive biomacromolecule. Previously, Val-Pro-Gly-Val-Gly peptides have been conjugated to a dendrimer for designing an elastin-mimetic dendrimer. In this study, various elastin-mimetic dendrimers using different length peptides and different dendrimer generations were synthesized to control the temperature dependency. The elastin-mimetic dendrimers formed β-turn structure by heating, which was similar to the elastin-like peptides. The elastin-mimetic dendrimers exhibited an inverse phase transition, largely depending on the peptide length and slightly depending on the dendrimer generation. The elastin-mimetic dendrimers formed aggregates after the phase transition. The endothermal peak was observed in elastin-mimetic dendrimers with long peptides, but not with short ones. The peptide length and the dendrimer generation are important factors to tune the temperature dependency on the elastin-mimetic dendrimer. Copyright © 2013 Wiley Periodicals, Inc.

Investigation of water-soluble elastin as a multifunctional cosmetic material: Moisturizing and whitening effects.

PubMed

Inoue, Asako; Hikima, Tomohiro; Taniguchi, Suguru; Nose, Takeru; Maeda, Iori

Elastin and collagen are extracellular matrix proteins that are widely distributed in the body. Although elastin essentially functions as a skin moisturizer, there have been few reports on its other fundamental chemical and biological functions. In this study, we investigated the moisturizing and whitening (tyrosinase inhibition) effects of elastin to examine its usefulness as a cosmetic material. Water-soluble hot alkali pig aorta (HAPA)-elastin was prepared from pig aorta using the hot alkali method. HAPA-elastin showed a widely distributed molecular weight and had a coacervation property that mediated reversible self-assembly of its molecules with increasing temperature. Amino acid analysis of HAPA-elastin showed a high content (81.5%) of hydrophobic amino acids such as Gly, Ala, Val, and Pro. Des (desmosine) and Ide (isodesmosine), which are characteristic amino acids of elastin, accounted for more than 0.4% of the total amino acid content. HAPA-elastin showed a moisture-retaining property. The water content of skin samples treated with and without HAPA-elastin was 77.2% ± 7.8% and 49.4% ± 10.1%, respectively. HAPA-elastin also inhibited tyrosinase activity by 11.3% ± 3.9%. The results obtained indicate that elastin has a useful function as a cosmetic material.

Non-invasive imaging of cellulose microfibril orientation within plant cell walls by polarized Raman microspectroscopy.

PubMed

Sun, Lan; Singh, Seema; Joo, Michael; Vega-Sanchez, Miguel; Ronald, Pamela; Simmons, Blake A; Adams, Paul; Auer, Manfred

2016-01-01

Cellulose microfibrils represent the major scaffold of plant cell walls. Different packing and orientation of the microfibrils at the microscopic scale determines the macroscopic properties of cell walls and thus affect their functions with a profound effect on plant survival. We developed a polarized Raman microspectroscopic method to determine cellulose microfibril orientation within rice plant cell walls. Employing an array of point measurements as well as area imaging and subsequent Matlab-assisted data processing, we were able to characterize the distribution of cellulose microfibril orientation in terms of director angle and anisotropy magnitude. Using this approach we detected differences between wild type rice plants and the rice brittle culm mutant, which shows a more disordered cellulose microfibril arrangement, and differences between different tissues of a wild type rice plant. This novel non-invasive Raman imaging approach allows for quantitative assessment of cellulose fiber orientation in cell walls of herbaceous plants, an important advancement in cell wall characterization. © 2015 Wiley Periodicals, Inc.

Cellulose microfibril deposition: coordinated activity at the plant plasma membrane.

PubMed

Lindeboom, J; Mulder, B M; Vos, J W; Ketelaar, T; Emons, A M C

2008-08-01

Plant cell wall production is a membrane-bound process. Cell walls are composed of cellulose microfibrils, embedded inside a matrix of other polysaccharides and glycoproteins. The cell wall matrix is extruded into the existing cell wall by exocytosis. This same process also inserts the cellulose synthase complexes into the plasma membrane. These complexes, the nanomachines that produce the cellulose microfibrils, move inside the plasma membrane leaving the cellulose microfibrils in their wake. Cellulose microfibril angle is an important determinant of cell development and of tissue properties and as such relevant for the industrial use of plant material. Here, we provide an integrated view of the events taking place in the not more than 100 nm deep area in and around the plasma membrane, correlating recent results provided by the distinct field of plant cell biology. We discuss the coordinated activities of exocytosis, endocytosis, and movement of cellulose synthase complexes while producing cellulose microfibrils and the link of these processes to the cortical microtubules.

Structure of cellulose microfibrils in mature cotton fibres.

PubMed

Martínez-Sanz, Marta; Pettolino, Filomena; Flanagan, Bernadine; Gidley, Michael J; Gilbert, Elliot P

2017-11-01

The structure of cellulose microfibrils in mature cotton fibres from three varieties - Gossypium hirsutum, G. barbadense and G. arboreum - has been investigated by a multi-technique approach combining small angle scattering techniques with spectroscopy and diffraction. Cellulose microfibrils present a Iβ-rich crystalline structure with limited surface disorder. Small angle scattering (SAXS and SANS) data have been successfully fitted using a core-shell model and the results obtained indicate that the cellulose microfibrils, formed by the association of 2-3 elementary fibrils, are composed of a ca. 2nm impermeable crystalline core, surrounded by a partially hydrated paracrystalline shell, with overall cross-sections of ca. 3.6-4.7nm. Different low levels of cell wall matrix components have a strong impact on the microfibril architecture and enable moisture penetration upon hydration. Furthermore, the higher amounts of non-cellulosic components in G. barbadense result in a less dense packing of cellulose microfibrils and increased solvent accessibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

In vitro synthesis of cellulose microfibrils by a membrane protein from protoplasts of the non-vascular plant Physcomitrella patens.

PubMed

Cho, Sung Hyun; Du, Juan; Sines, Ian; Poosarla, Venkata Giridhar; Vepachedu, Venkata; Kafle, Kabindra; Park, Yong Bum; Kim, Seong H; Kumar, Manish; Nixon, B Tracy

2015-09-01

Plant cellulose synthases (CesAs) form a family of membrane proteins that are associated with hexagonal structures in the plasma membrane called CesA complexes (CSCs). It has been difficult to purify plant CesA proteins for biochemical and structural studies. We describe CesA activity in a membrane protein preparation isolated from protoplasts of Physcomitrella patens overexpressing haemagglutinin (HA)-tagged PpCesA5. Incubating the membrane preparation with UDP-glucose predominantly produced cellulose. Negative-stain EM revealed microfibrils. Cellulase bound to and degraded these microfibrils. Vibrational sum frequency generation (SFG) spectroscopic analysis detected the presence of crystalline cellulose in the microfibrils. Putative CesA proteins were frequently observed attached to the microfibril ends. Combined cross-linking and gradient centrifugation showed bundles of cellulose microfibrils with larger particle aggregates, possibly CSCs. These results suggest that P. patens is a useful model system for biochemical and structural characterization of plant CSCs and their components. © 2015 Authors; published by Portland Press Limited.

Different Conformations of Surface Cellulose Molecules in Native Cellulose Microfibrils Revealed by Layer-by-Layer Peeling.

PubMed

Funahashi, Ryunosuke; Okita, Yusuke; Hondo, Hiromasa; Zhao, Mengchen; Saito, Tsuguyuki; Isogai, Akira

2017-11-13

Layer-by-layer peeling of surface molecules of native cellulose microfibrils was performed using a repeated sequential process of 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation followed by hot alkali extraction. Both highly crystalline algal and tunicate celluloses and low-crystalline cotton and wood celluloses were investigated. Initially, the C6-hydroxy groups of the outermost surface molecules of each algal cellulose microfibril facing the exterior had the gauche-gauche (gg) conformation, whereas those facing the interior had the gauche-trans (gt) conformation. All the other C6-hydroxy groups of the cellulose molecules inside the microfibrils contributing to crystalline cellulose I had the trans-gauche (tg) conformation. After surface peeling, the originally second-layer molecules from the microfibril surface became the outermost surface molecules, and the original tg conformation changed to gg and gt conformations. The plant cellulose microfibrils likely had disordered structures for both the outermost surface and second-layer molecules, as demonstrated using the same layer-by-layer peeling technique.

A survey of cellulose microfibril patterns in dividing, expanding, and differentiating cells of Arabidopsis thaliana.

PubMed

Fujita, Miki; Wasteneys, Geoffrey O

2014-05-01

Cellulose microfibrils are critical for plant cell specialization and function. Recent advances in live cell imaging of fluorescently tagged cellulose synthases to track cellulose synthesis have greatly advanced our understanding of cellulose biosynthesis. Nevertheless, cellulose deposition patterns remain poorly described in many cell types, including those in the process of division or differentiation. In this study, we used field emission scanning electron microscopy analysis of cryo-planed tissues to determine the arrangement of cellulose microfibrils in various faces of cells undergoing cytokinesis or specialized development, including cell types in which cellulose cannot be imaged by conventional approaches. In dividing cells, we detected microfibrillar meshworks in the cell plates, consistent with the concentration at the cell plate of cellulose synthase complexes, as detected by fluorescently tagged CesA6. We also observed a loss of parallel cellulose microfibril orientation in walls of the mother cell during cytokinesis, which corresponded with the loss of fluorescently tagged cellulose synthase complexes from these surfaces. In recently formed guard cells, microfibrils were randomly organized and only formed a highly ordered circumferential pattern after pore formation. In pit fields, cellulose microfibrils were arranged in circular patterns around plasmodesmata. Microfibrils were random in most cotyledon cells except the epidermis and were parallel to the growth axis in trichomes. Deposition of cellulose microfibrils was spatially delineated in metaxylem and protoxylem cells of the inflorescence stem, supporting recent studies on microtubule exclusion mechanisms.

Elastin distribution in the normal uterus, uterine leiomyomas, adenomyosis and adenomyomas: a comparison.

PubMed

Zheng, Wei-Qiang; Ma, Rong; Zheng, Jian-Ming; Gong, Zhi-Jing

2006-04-01

To describe the histologic distribution of elastin in the nonpregnant human uterus, uterine leiomyomas, adenomyosis and adenomyomas. Uteri were obtained from women undergoing hysterectomy for benign conditions, including 26 cases of uterine leiomyomas, 24 cases of adenomyosis, 18 adenomyomas and 6 cases of autopsy specimens. Specific histochemical staining techniques were employed in order to demonstrate the distribution of elastin. The distribution of elastin components in the uterus was markedly uneven and showed a decreasing gradient from outer to inner myometrium. No elastin was present within leiomyomas, adenomyomas or adenomyosis. The distribution of elastin may help explain the normal function of the myometrium in labor. It implies that the uneven distribution of elastin components and absence of elastin within leiomyomas, adenomyomas and adenomyosis could be of some clinical significance. The altered elastin distribution in disease states may help explain such symptoms as dysmenorrhea in uterine endometriosis.

Dynamic expression of chymotrypsin-like elastase 1 over the course of murine lung development

PubMed Central

Liu, Sheng; Young, Sarah Marie

2014-01-01

Postnatal lung development requires coordination of three processes (surface area expansion, microvascular growth, and matrix remodeling). Because normal elastin structure is important for lung morphogenesis, because physiological remodeling of lung elastin has never been defined, and because elastin remodeling is angiogenic, we sought to test the hypothesis that, during lung development, elastin is remodeled in a defined temporal-spatial pattern, that a novel protease is associated with this remodeling, and that angiogenesis is associated with elastin remodeling. By elastin in situ zymography, lung elastin remodeling increased 24-fold between embryonic day (E) 15.5 and postnatal day (PND) 14. Remodeling was restricted to major vessels and airways on PND1 with a sevenfold increase in alveolar wall elastin remodeling from PND1 to PND14. By inhibition assays and literature review, we identified chymotrypsin-like elastase 1 (CELA1) as a potential mediator of elastin remodeling. CELA1 mRNA levels increased 12-fold from E15.5 to PND9, and protein levels increased 3.4-fold from E18.5 to PND9. By costaining experiments, the temporal-spatial pattern of CELA1 expression matched that of elastin remodeling, and 58–85% of CELA1+ cells were <10 μm from an elastase signal. An association between elastin remodeling and angiogenesis was tested by similar methods. At PND7 and PND14, 60–95% of angiogenin+ cells were associated with elastin remodeling. Both elastase inhibition and CELA1 silencing impaired angiogenesis in vitro. Our data defines the temporal-spatial pattern of elastin remodeling during lung development, demonstrates an association of this remodeling with CELA1, and supports a role for elastin remodeling in regulating angiogenesis. PMID:24793170

In vitro versus in vivo cellulose microfibrils from plant primary wall synthases: structural differences.

PubMed

Lai-Kee-Him, Joséphine; Chanzy, Henri; Müller, Martin; Putaux, Jean-Luc; Imai, Tomoya; Bulone, Vincent

2002-10-04

Detergent extracts of microsomal fractions from suspension cultured cells of Rubus fruticosus (blackberry) were tested for their ability to synthesize in vitro sizable quantities of cellulose from UDP-glucose. Both Brij 58 and taurocholate were effective and yielded a substantial percentage of cellulose microfibrils together with (1-->3)-beta-d-glucan (callose). The taurocholate extracts, which did not require the addition of Mg(2+), were the most efficient, yielding roughly 20% of cellulose. This cellulose was characterized after callose removal by methylation analysis, electron microscopy, and electron and x-ray synchrotron diffractions; its resistance toward the acid Updegraff reagent was also evaluated. The cellulose microfibrils synthesized in vitro had the same diameter as the endogenous microfibrils isolated from primary cell walls. Both polymers diffracted as cellulose IV(I), a disorganized form of cellulose I. Besides these similarities, the in vitro microfibrils had a higher perfection and crystallinity as well as a better resistance toward the Updegraff reagent. These differences can be attributed to the mode of synthesis of the in vitro microfibrils that are able to grow independently in a neighbor-free environment, as opposed to the cellulose in the parent cell walls where new microfibrils have to interweave with the already laid polymers, with the result of a number of structural defects.

The Effect of Water Molecules on Mechanical Properties of Bamboo Microfibrils

NASA Astrophysics Data System (ADS)

Rahbar, Nima

Bamboo fibers have higher strength-to-weight ratios than steel and concrete. The unique properties of bamboo fibers come from their natural composite structures that comprise mainly cellulose nanofibrils in a matrix of intertwined hemicellulose and lignin called lignin-carbohydrate complex (LCC). Here, we have utilized atomistic simulations to investigate the mechanical properties and mechanisms of interactions between these materials, in the presence of water molecules. Our results suggest that hemicellulose exhibits better mechanical properties and lignin shows greater tendency to adhere to cellulose nanofibrils. Consequently, the role of hemicellulose found to be enhancing the mechanical properties and lignin found to be providing the strength of bamboo fibers. The abundance of Hbonds in hemicellulose chains is responsible for improving the mechanical behavior of LCC. The strong van der Waals forces between lignin molecules and cellulose nanofibrils is responsible for higher adhesion energy between LCC/cellulose nanofibrils. We also found out that the amorphous regions of cellulose nanofibrils is the weakest interface in bamboo Microfibrils. In presence of water, the elastic modulus of lignin increases at low water content (less than 10 NSF CAREER Grant No. 1261284.

Vascular nanomedicine: Site specific delivery of elastin stabilizing therapeutics to damaged arteries

NASA Astrophysics Data System (ADS)

Sinha, Aditi

Elastin, a structural protein in the extra-cellular matrix, plays a critical role in the normal functioning of blood vessels. Apart from performing its primary function of providing resilience to arteries, it also plays major role in regulating cell-cell and cell-matrix interactions, response to injury, and morphogenesis. Medial arterial calcification (MAC) and abdominal aortic aneurysm (AAA) are two diseases where the structural and functional integrity of elastin is severely compromised. Although the clinical presentation of MAC and AAA differ, they have one common underlying causative mechanism---pathological degradation of elastin. Hence prevention of elastin degradation in the early stages of MAC and AAA can mitigate, partially if not wholly, the fatal consequences of both the diseases. The work presented here is motivated by the overwhelming statistics of people afflicted by elastin associated cardiovascular diseases and the unavailability of cure for the same. Overall goal of our research is to understand role of elastin degradation in cardiovascular diseases and to develop a targeted vascular drug delivery system that is minimally invasive, biodegradable, and non-toxic, that prevents elastin from degradation. Our hope is that such treatment will also help regenerate elastin, thereby providing a multi-fold treatment option for elasto-degenerative vascular diseases. For this purpose, we have first confirmed the combined role of degraded elastin and hyperglycemia in the pathogenesis of MAC. We have shown that in the absence of degraded elastin and TGF-beta1 (abundantly present in diabetic arteries) vascular smooth muscle cells maintain their homeostatic state, regardless of environmental glucose concentrations. However simultaneous exposure to glucose, elastin peptides and TGF-beta1 causes the pathological transgenesis of vascular cells to osteoblast-like cells. We show that plant derived polyphenols bind to vascular elastin with great affinity resulting in improved resistance to elastolytic digestion. We further show that the same polyphenols interact with monomeric tropoelastin released by the vascular cells and dramatically increasing their self-assembly in-vitro. In addition, we demonstrate the elastogenic ability of these polyphenols in aiding the crosslinking of tropoelastin released by aneurysmal cells converting it into mature elastin. Finally, we developed a nanoparticle system functionalized with elastin antibody on the surface that, upon systemic delivery, can recognize and bind to sites of damaged elastin in the aorta. We are able to show that this nanoparticle system works in representative animal models for MAC and AAA. These nanoparticles demonstrated spatial and functional specificity for degraded elastin. In conclusion, our work is focused on understanding the role of elastin degradation in vascular calcification and aortic aneurysms. We tested approaches to halt elastin degradation and to regenerate elastin in arteries so that homeostasis can be achieved.

MiR-29-mediated elastin down-regulation contributes to inorganic phosphorus-induced osteoblastic differentiation in vascular smooth muscle cells.

PubMed

Sudo, Ryo; Sato, Fumiaki; Azechi, Takuya; Wachi, Hiroshi

2015-12-01

Vascular calcification increases the risk of cardiovascular mortality. We previously reported that expression of elastin decreases with progression of inorganic phosphorus (Pi)-induced vascular smooth muscle cell (VSMC) calcification. However, the regulatory mechanisms of elastin mRNA expression during vascular calcification remain unclear. MicroRNA-29 family members (miR-29a, b and c) are reported to mediate elastin mRNA expression. Therefore, we aimed to determine the effect of miR-29 on elastin expression and Pi-induced vascular calcification. Calcification of human VSMCs was induced by Pi and evaluated measuring calcium deposition. Pi stimulation promoted Ca deposition and suppressed elastin expression in VSMCs. Knockdown of elastin expression by shRNA also promoted Pi-induced VSMC calcification. Elastin pre-mRNA measurements indicated that Pi stimulation suppressed elastin expression without changing transcriptional activity. Conversely, Pi stimulation increased miR-29a and miR-29b expression. Inhibition of miR-29 recovered elastin expression and suppressed calcification in Pi-treated VSMCs. Furthermore, over-expression of miR-29b promoted Pi-induced VSMC calcification. RT-qPCR analysis showed knockdown of elastin expression in VSMCs induced expression of osteoblast-related genes, similar to Pi stimulation, and recovery of elastin expression by miR-29 inhibition reduced their expression. Our study shows that miR-29-mediated suppression of elastin expression in VSMCs plays a pivotal role in osteoblastic differentiation leading to vascular calcification. © 2015 The Molecular Biology Society of Japan and Wiley Publishing Asia Pty Ltd.

Mechanical contribution of lamellar and interlamellar elastin along the mouse aorta.

PubMed

Clark, T E; Lillie, M A; Vogl, A W; Gosline, J M; Shadwick, R E

2015-10-15

The mechanical properties of aortic elastin vary regionally, but the microstructural basis for this variation is unknown. This study was designed to identify the relative contributions of lamellar and interlamellar elastin to circumferential load bearing in the mouse thoracic and abdominal aortas. Forces developed in uniaxial tests of samples of fresh and autoclaved aorta were correlated with elastin content and morphology obtained from histology and multiphoton laser scanning microscopy. Autoclaving should render much of the interlamellar elastin mechanically incompetent. In autoclaved tissue force per unit sample width correlated with lamellar elastin content (P≪0.001) but not total elastin content. In fresh tissue at low strain where elastin dominates the mechanical response, forces were higher than in the autoclaved tissue, but force did not correlate with total elastin content. Therefore although interlamellar elastin likely contributed to the stiffness in the fresh aorta, its contribution appeared not in proportion to its quantity. In both fresh and autoclaved tissue, elastin stiffness consistently decreased along the abdominal aorta, a key area for aneurysm development, and this difference could not be fully accounted for on the basis of either lamellar or total elastin content. These findings are relevant to the development of mathematical models of arterial mechanics, particularly for mouse models of arterial diseases involving elastic tissue. In microstructural based models the quantity of each mural constituent determines its contribution to the total response. This study shows elastin's mechanical response cannot necessarily be accounted for on the basis of fibre quantity, orientation, and modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Elastin Calcification and its Prevention with Aluminum Chloride Pretreatment

PubMed Central

Vyavahare, Narendra; Ogle, Matthew; Schoen, Frederick J.; Levy, Robert J.

1999-01-01

Elastin, an abundant structural protein present in the arterial wall, is prone to calcification in a number of disease processes including porcine bioprosthetic heart valve calcification and atherosclerosis. The mechanisms of elastin calcification are not completely elucidated. In the present work, we demonstrated calcification of purified elastin in rat subdermal implants (Ca2+ = 89.73 ± 9.84 μg/mg after 21 days versus control, unimplanted Ca2+ = 0.16 ± 0.04 μg/mg). X-ray diffraction analysis along with resolution enhanced FTIR spectroscopy demonstrated the mineral phase to be a poorly crystalline hydroxyapatite. We investigated the time course of calcification, the effect of glutaraldehyde crosslinking on calcification, and mechanisms of inhibition of elastin calcification by pretreatment with aluminum chloride (AlCl3). Glutaraldehyde pretreatment did not affect calcification (Ca2+ = 89.06 ± 17.93 μg/mg for glutaraldehyde crosslinked elastin versus Ca2+ = 89.73 ± 9.84 μg/mg for uncrosslinked elastin). This may be explained by radioactive (3H) glutaraldehyde studies showing very low reactivity between glutaraldehyde and elastin. Our results further demonstrated that AlCl3 pretreatment of elastin led to complete inhibition of elastin calcification using 21-day rat subdermal implants, irrespective of glutaraldehyde crosslinking (Ca2+ = 0.73–2.15 μg/mg for AlCl3 pretreated elastin versus 89.73 ± 9.84 for untreated elastin). The AlCl3 pretreatment caused irreversible binding of aluminum ions to elastin, as assessed by atomic emission spectroscopy. Moreover, aluminum ion binding altered the spatial configuration of elastin as shown by circular dichroism (CD), Fourier transform infrared (FTIR), and 13C nuclear magnetic resonance (NMR) spectroscopy studies, suggesting a net structural change including a reduction in the extent of β sheet structures and an increase in coil-turn conformations. Thus, it is concluded that purified elastin calcifies in rat subdermal implants, and that the AlCl3-pretreated elastin completely resists calcification due to irreversible aluminum ion binding and subsequent structural alterations caused by AlCl3. PMID:10487855

Mechanistic Insights into Elastin Degradation by Pseudolysin, the Major Virulence Factor of the Opportunistic Pathogen Pseudomonas aeruginosa

PubMed Central

Yang, Jie; Zhao, Hui-Lin; Ran, Li-Yuan; Li, Chun-Yang; Zhang, Xi-Ying; Su, Hai-Nan; Shi, Mei; Zhou, Bai-Cheng; Chen, Xiu-Lan; Zhang, Yu-Zhong

2015-01-01

Pseudolysin is the most abundant protease secreted by Pseudomonas aeruginosa and is the major extracellular virulence factor of this opportunistic human pathogen. Pseudolysin destroys human tissues by solubilizing elastin. However, the mechanisms by which pseudolysin binds to and degrades elastin remain elusive. In this study, we investigated the mechanism of action of pseudolysin on elastin binding and degradation by biochemical assay, microscopy and site-directed mutagenesis. Pseudolysin bound to bovine elastin fibers and preferred to attack peptide bonds with hydrophobic residues at the P1 and P1’ positions in the hydrophobic domains of elastin. The time-course degradation processes of both bovine elastin fibers and cross-linked human tropoelastin by pseudolysin were further investigated by microscopy. Altogether, the results indicate that elastin degradation by pseudolysin began with the hydrophobic domains on the fiber surface, followed by the progressive disassembly of macroscopic elastin fibers into primary structural elements. Moreover, our site-directed mutational results indicate that five hydrophobic residues in the S1-S1’ sub-sites played key roles in the binding of pseudolysin to elastin. This study sheds lights on the pathogenesis of P. aeruginosa infection. PMID:25905792

Alternative Splicing and Tissue-specific Elastin Misassembly Act as Biological Modifiers of Human Elastin Gene Frameshift Mutations Associated with Dominant Cutis Laxa*

PubMed Central

Sugitani, Hideki; Hirano, Eiichi; Knutsen, Russell H.; Shifren, Adrian; Wagenseil, Jessica E.; Ciliberto, Christopher; Kozel, Beth A.; Urban, Zsolt; Davis, Elaine C.; Broekelmann, Thomas J.; Mecham, Robert P.

2012-01-01

Elastin is the extracellular matrix protein in vertebrates that provides elastic recoil to blood vessels, the lung, and skin. Because the elastin gene has undergone significant changes in the primate lineage, modeling elastin diseases in non-human animals can be problematic. To investigate the pathophysiology underlying a class of elastin gene mutations leading to autosomal dominant cutis laxa, we engineered a cutis laxa mutation (single base deletion) into the human elastin gene contained in a bacterial artificial chromosome. When expressed as a transgene in mice, mutant elastin was incorporated into elastic fibers in the skin and lung with adverse effects on tissue function. In contrast, only low levels of mutant protein incorporated into aortic elastin, which explains why the vasculature is relatively unaffected in this disease. RNA stability studies found that alternative exon splicing acts as a modifier of disease severity by influencing the spectrum of mutant transcripts that survive nonsense-mediated decay. Our results confirm the critical role of the C-terminal region of tropoelastin in elastic fiber assembly and suggest tissue-specific differences in the elastin assembly pathway. PMID:22573328

Elastin as a self-organizing biomaterial: use of recombinantly expressed human elastin polypeptides as a model for investigations of structure and self-assembly of elastin.

PubMed

Keeley, Fred W; Bellingham, Catherine M; Woodhouse, Kimberley A

2002-02-28

Elastin is the major extracellular matrix protein of large arteries such as the aorta, imparting characteristics of extensibility and elastic recoil. Once laid down in tissues, polymeric elastin is not subject to turnover, but is able to sustain its mechanical resilience through thousands of millions of cycles of extension and recoil. Elastin consists of ca. 36 domains with alternating hydrophobic and cross-linking characteristics. It has been suggested that these hydrophobic domains, predominantly containing glycine, proline, leucine and valine, often occurring in tandemly repeated sequences, are responsible for the ability of elastin to align monomeric chains for covalent cross-linking. We have shown that small, recombinantly expressed polypeptides based on sequences of human elastin contain sufficient information to self-organize into fibrillar structures and promote the formation of lysine-derived cross-links. These cross-linked polypeptides can also be fabricated into membrane structures that have solubility and mechanical properties reminiscent of native insoluble elastin. Understanding the basis of the self-organizational ability of elastin-based polypeptides may provide important clues for the general design of self-assembling biomaterials.

The Effect of Static Stretch on Elastin Degradation in Arteries

PubMed Central

Chow, Ming-Jay; Choi, Myunghwan; Yun, Seok Hyun; Zhang, Yanhang

2013-01-01

Previously we have shown that gradual changes in the structure of elastin during an elastase treatment can lead to important transition stages in the mechanical behavior of arteries [1]. However, in vivo arteries are constantly being loaded due to systolic and diastolic pressures and so understanding the effects of loading on the enzymatic degradation of elastin in arteries is important. With biaxial tensile testing, we measured the mechanical behavior of porcine thoracic aortas digested with a mild solution of purified elastase (5 U/mL) in the presence of a static stretch. Arterial mechanical properties and biochemical composition were analyzed to assess the effects of mechanical stretch on elastin degradation. As elastin is being removed, the dimensions of the artery increase by more than 20% in both the longitude and circumference directions. Elastin assays indicate a faster rate of degradation when stretch was present during the digestion. A simple exponential decay fitting confirms the time constant for digestion with stretch (0.11±0.04 h−1) is almost twice that of digestion without stretch (0.069±0.028 h−1). The transition from J-shaped to S-shaped stress vs. strain behavior in the longitudinal direction generally occurs when elastin content is reduced by about 60%. Multiphoton image analysis confirms the removal/fragmentation of elastin and also shows that the collagen fibers are closely intertwined with the elastin lamellae in the medial layer. After removal of elastin, the collagen fibers are no longer constrained and become disordered. Release of amorphous elastin during the fragmentation of the lamellae layers is observed and provides insights into the process of elastin degradation. Overall this study reveals several interesting microstructural changes in the extracellular matrix that could explain the resulting mechanical behavior of arteries with elastin degradation. PMID:24358135

Engineering aqueous fiber assembly into silk-elastin-like protein polymers.

PubMed

Zeng, Like; Jiang, Linan; Teng, Weibing; Cappello, Joseph; Zohar, Yitshak; Wu, Xiaoyi

2014-07-01

Self-assembled peptide/protein nanofibers are valuable 1D building blocks for creating complex structures with designed properties and functions. It is reported that the self-assembly of silk-elastin-like protein polymers into nanofibers or globular aggregates in aqueous solutions can be modulated by tuning the temperature of the protein solutions, the size of the silk blocks, and the charge of the elastin blocks. A core-sheath model is proposed for nanofiber formation, with the silk blocks in the cores and the hydrated elastin blocks in the sheaths. The folding of the silk blocks into stable cores--affected by the size of the silk blocks and the charge of the elastin blocks--plays a critical role in the assembly of silk-elastin nanofibers. Furthermore, enhanced hydrophobic interactions between the elastin blocks at elevated temperatures greatly influence the nanoscale features of silk-elastin nanofibers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Circulating elastin peptides, role in vascular pathology.

PubMed

Robert, L; Labat-Robert, J

2014-12-01

The atherosclerotic process starts with the degradation of elastic fibers. Their presence was demonstrated in the circulation as well as several of their biological properties elucidated. We described years ago a procedure to obtain large elastin peptides by organo-alkaline hydrolysis, κ-elastin. This method enabled also the preparation of specific antibodies used to determine elastin peptides, as well as anti-elastin antibodies in body fluids and tissue extracts. Elastin peptides were determined in a large number of human blood samples. Studies were carried out to explore their pharmacological properties. Similar recent studies by other laboratories confirmed our findings and arose new interest in circulating elastin peptides for their biological activities. This recent trend justified the publication of a review of the biological and pathological activities of elastin peptides demonstrated during our previous studies, subject of this article. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Mineral-Ground Micro-Fibrillated Cellulose Reinforcement for Polymer Compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phipps, Jon; Ireland, Sean; Skuse, David

2017-01-01

ORNL worked with Imerys to demonstrate reinforcement of additive manufacturing feedstock materials using mineral-ground microfibrillated cellulose (MFC). Properly prepared/dried mineral-ground cellulose microfibrils significantly improved mechanical properties of both ABS and PLA resins. While tensile strength increases up to ~40% were observed, elastic modulus of the both resins doubled with the addition of 30% MFC.

Circulating Anti-Elastin Antibody Levels and Arterial Disease Characteristics: Associations with Arterial Stiffness and Atherosclerosis.

PubMed

Lee, Seung-Hyun; Shin, Kihyuk; Park, Sungha; Kang, Seok-Min; Choi, Donghoon; Lee, Seung-Hyo; Lee, Sang-Hak

2015-11-01

Elastin is a major arterial structural protein, and elastin-derived peptides are related to arterial change. We previously reported on a novel assay developed using aortic elastin peptides; however, its clinical implications remain unclear. In this study, we assessed whether anti-elastin antibody titers reflect the risk of coronary artery disease (CAD) or its characteristics. We included 174 CAD patients and 171 age- and sex-matched controls. Anti-elastin antibody titers were quantified by enzyme-linked immunosorbent assay. Parameters of arterial stiffness, including the augmentation index (AI) and heart-to-femoral pulse wave velocity (hfPWV), were measured non-invasively. The clinical and angiographic characteristics of CAD patients were also evaluated. Associations between anti-elastin levels and vascular characteristics were examined by linear regression analysis. The median blood level of anti-elastin was significantly lower in the CAD group than in the controls [197 arbitrary unit (a.u.) vs. 63 a.u., p<0.001]. Levels of anti-elastin were significantly lower in men and in subjects with hypertension, diabetes mellitus, hyperlipidemia, or high hfPWV. Nevertheless, anti-elastin levels were not dependent on atherothrombotic events or the angiographic severity of CAD. In a multivariate analysis, male sex (β=-0.38, p<0.001), diabetes mellitus (β=-0.62, p<0.001), hyperlipidemia (β=-0.29, p<0.001), and AI (β=-0.006, p=0.02) were ultimately identified as determinants of anti-elastin levels. Lower levels of anti-elastin are related to CAD. The association between antibody titers and CAD is linked to arterial stiffness rather than the advancement of atherosclerosis.

Fabricated Elastin.

PubMed

Yeo, Giselle C; Aghaei-Ghareh-Bolagh, Behnaz; Brackenreg, Edwin P; Hiob, Matti A; Lee, Pearl; Weiss, Anthony S

2015-11-18

The mechanical stability, elasticity, inherent bioactivity, and self-assembly properties of elastin make it a highly attractive candidate for the fabrication of versatile biomaterials. The ability to engineer specific peptide sequences derived from elastin allows the precise control of these physicochemical and organizational characteristics, and further broadens the diversity of elastin-based applications. Elastin and elastin-like peptides can also be modified or blended with other natural or synthetic moieties, including peptides, proteins, polysaccharides, and polymers, to augment existing capabilities or confer additional architectural and biofunctional features to compositionally pure materials. Elastin and elastin-based composites have been subjected to diverse fabrication processes, including heating, electrospinning, wet spinning, solvent casting, freeze-drying, and cross-linking, for the manufacture of particles, fibers, gels, tubes, sheets and films. The resulting materials can be tailored to possess specific strength, elasticity, morphology, topography, porosity, wettability, surface charge, and bioactivity. This extraordinary tunability of elastin-based constructs enables their use in a range of biomedical and tissue engineering applications such as targeted drug delivery, cell encapsulation, vascular repair, nerve regeneration, wound healing, and dermal, cartilage, bone, and dental replacement. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabricated elastin

PubMed Central

Yeo, Giselle C.; Weiss, Anthony S.

2015-01-01

The mechanical stability, elasticity, inherent bioactivity, and self-assembly properties of elastin make it a highly attractive candidate for the fabrication of versatile biomaterials. The ability to engineer specific peptide sequences derived from elastin allows for precise control of these physicochemical and organizational characteristics, and further broadens the diversity of elastin-based applications. Elastin and elastin-like peptides can also be modified or blended with other natural or synthetic moieties, including peptides, proteins, polysaccharides and polymers, to augment existing capabilities or confer additional architectural and biofunctional features to compositionally pure materials. Elastin and elastin-based composites have been subjected to diverse fabrication processes, including heating, electrospinning, wet spinning, solvent casting, freeze-drying, and cross-linking, for the manufacture of particles, fibers, gels, tubes, sheets and films. The resulting materials can be tailored to possess specific strength, elasticity, morphology, topography, porosity, wettability, surface charge and bioactivity. This extraordinary tunability of elastin-based constructs enables their use in a range of biomedical and tissue engineering applications such as targeted drug delivery, cell encapsulation, vascular repair, nerve regeneration, wound healing, and dermal, cartilage, bone and dental replacement. PMID:25771993

Elastic modulus of single cellulose microfibrils from tunicate measured by atomic force microscopy.

PubMed

Iwamoto, Shinichiro; Kai, Weihua; Isogai, Akira; Iwata, Tadahisa

2009-09-14

The elastic modulus of single microfibrils from tunicate ( Halocynthia papillosa ) cellulose was measured by atomic force microscopy (AFM). Microfibrils with cross-sectional dimensions 8 x 20 nm and several micrometers in length were obtained by oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) as a catalyst and subsequent mechanical disintegration in water and by sulfuric acid hydrolysis. The nanocellulosic materials were deposited on a specially designed silicon wafer with grooves 227 nm in width, and a three-point bending test was applied to determine the elastic modulus using an AFM cantilever. The elastic moduli of single microfibrils prepared by TEMPO-oxidation and acid hydrolysis were 145.2 +/- 31.3 and 150.7 +/- 28.8 GPa, respectively. The result showed that the experimentally determined modulus of the highly crystalline tunicate microfibrils was in agreement with the elastic modulus of native cellulose crystals.

Quasi-one-dimensional arrangement of silver nanoparticles templated by cellulose microfibrils.

PubMed

Wu, Min; Kuga, Shigenori; Huang, Yong

2008-09-16

We demonstrate a simple, facile approach to the deposition of silver nanoparticles on the surface of cellulose microfibrils with a quasi-one-dimensional arrangement. The process involves the generation of aldehyde groups by oxidizing the surface of cellulose microfibrils and then the assembly of silver nanoparticles on the surface by means of the silver mirror reaction. The linear nature of the microfibrils and the relatively uniform surface chemical modification result in a uniform linear distribution of silver particles along the microfibrils. The effects of various reaction parameters, such as the reaction time for the reduction process and employed starting materials, have been investigated by transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy. Additionally, the products were examined for their electric current-voltage characteristics, the results showing that these materials had an electric conductivity of approximately 5 S/cm, being different from either the oxidated cellulose or bulk silver materials by many orders of magnitude.

Unraveling cellulose microfibrils: a twisted tale.

PubMed

Hadden, Jodi A; French, Alfred D; Woods, Robert J

2013-10-01

Molecular dynamics (MD) simulations of cellulose microfibrils are pertinent to the paper, textile, and biofuels industries for their unique capacity to characterize dynamic behavior and atomic-level interactions with solvent molecules and cellulase enzymes. While high-resolution crystallographic data have established a solid basis for computational analysis of cellulose, previous work has demonstrated a tendency for modeled microfibrils to diverge from the linear experimental structure and adopt a twisted conformation. Here, we investigate the dependence of this twisting behavior on computational approximations and establish the theoretical basis for its occurrence. We examine the role of solvent, the effect of nonbonded force field parameters [partial charges and van der Waals (vdW) contributions], and the use of explicitly modeled oxygen lone pairs in both the solute and solvent. Findings suggest that microfibril twisting is favored by vdW interactions, and counteracted by both intrachain hydrogen bonds and solvent effects at the microfibril surface. Copyright © 2013 Wiley Periodicals, Inc.

Unraveling Cellulose Microfibrils: A Twisted Tale

PubMed Central

Hadden, Jodi A.; French, Alfred D.; Woods, Robert J.

2014-01-01

Molecular dynamics (MD) simulations of cellulose microfibrils are pertinent to the paper, textile, and biofuels industries for their unique capacity to characterize dynamic behavior and atomic-level interactions with solvent molecules and cellulase enzymes. While high-resolution crystallographic data have established a solid basis for computational analysis of cellulose, previous work has demonstrated a tendency for modeled microfibrils to diverge from the linear experimental structure and adopt a twisted conformation. Here, we investigate the dependence of this twisting behavior on computational approximations and establish the theoretical basis for its occurrence. We examine the role of solvent, the effect of nonbonded force field parameters [partial charges and van der Waals (vdW) contributions], and the use of explicitly modeled oxygen lone pairs in both the solute and solvent. Findings suggest that microfibril twisting is favored by vdW interactions, and counteracted by both intrachain hydrogen bonds and solvent effects at the microfibril surface. PMID:23681971

Tunicamycin Prevents Cellulose Microfibril Formation in Oocystis solitaria.

PubMed

Quader, H

1984-07-01

The effect of tunicamycin (TM) on the development of the cell wall in Oocystis solitaria has been investigated. It was found that 10 micromolar TM completely stops the assembly of new microfibrils as observed at the ultrastructural level. During cell wall formation, freeze fracture replicas of the E-face of the plasma membrane reveal two major substructures: the terminal complexes (TC), paired and unpaired, and the microfibril imprints extending from unpaired TCs. In cells treated for 3 hours or longer with TM, the TCs are no longer visible, whereas microfibril imprints are still present. Because of the reported highly selective mode of action of TM, our results implicate a role for lipid-intermediates in cellulose synthesis in O. solitaria. It is assumed that TM prevents the formation of a glycoprotein which probably is a fundamental part of the TCs and may act as a primer for the assembly of the microfibrils.

New Model of Wood Cell Wall Microfibril and Its Implications

Treesearch

Umesh P. Agarwal; Sally A. Ralph; Rick S. Reiner; Carlos Baez

2015-01-01

Traditionally it has been accepted that the cell walls are made up of microfibrils which are partly crystalline. However, based on the recently obtained Raman evidence that showed that the interior of the microfibril was significantly disordered and water accessible, a new model is proposed. In this model, the molecular chains of cellulose are still organized along the...

Novel high-strength biocomposites based on microfibrillated cellulose having nano-order-unit web-like network structure

NASA Astrophysics Data System (ADS)

Nakagaito, A. N.; Yano, H.

2005-01-01

A completely new kind of high-strength composite was manufactured using microfibrillated cellulose (MFC) derived from kraft pulp. Because of the unique structure of nano-order-scale interconnected fibrils and microfibrils greatly expanded in the surface area that characterizes MFC, it was possible to produce composites that exploit the extremely high strength of microfibrils. The Young’s modulus (E) and bending strength (σb) of composites using phenolic resin as binder achieved values up to 19 GPa and 370 MPa, respectively, with a density of 1.45 g/cm2, exhibiting outstanding mechanical properties for a plant-fiber-based composite.

Possible participation of transient sheets of 1. -->. 4-. beta. -glucans in the biosynthesis of cellulose I. [Acetobacter xylinum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colvin, J.R.

1983-01-01

It is suggested that a primary, essential stage in the biologic formation of a microfibril of cellulose I is an extracellular, lateral association of presynthesized (1..-->..4)-..beta..-D-glucans, by hydrogen bonding, to form long, thin sheets. These sheets then superimpose themselves nonenzymatically by London forces to form the nascent microfibril. The ends of the constituent glucans of the nascent microfibril may undergo extension or rearrangement of the type indicated by Maclachlan and colleagues. The formation of the metastable, native structure (cellulose I) may be deduced from the above suggestion as a natural consequence of closest packing of the sheets. The irreversibility ofmore » the change from cellulose I to cellulose II, either by mercerization or regeneration, also follows from the postulate. The suggestion also explains why cellulose microfibrils and chitin microfibrils may be formed contiguously in cell walls without interfering with each other. High-resolution electron micrographs of the tips of newly formed microfibrils of bacterial cellulose which had been very lightly negatively stained with sodium phosphotungstate are consistent with the suggestion. 33 references, 3 figures.« less

Influence of drying of chara cellulose on length/length distribution of microfibrils after acid hydrolysis.

PubMed

Horikawa, Yoshiki; Shimizu, Michiko; Saito, Tsuguyuki; Isogai, Akira; Imai, Tomoya; Sugiyama, Junji

2018-04-01

Chara is a genus of freshwater alga that is evolutionarily observed at the aquatic-terrestrial boundary, whose cellulose microfibrils are similar to those of terrestrial plants regarding the crystallinity and biosynthesis of cellulose. Oven-dried and never-dried celluloses samples were prepared from chara. Terrestrial plant cellulose samples were used as references. The lengths and length distributions of oven-dried and never-dried chara cellulose microfibrils after acid hydrolysis with or without pretreatment by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, which was used for efficient fibrillation of acid-hydrolyzed products, were observed by transmission electron microscopy. All terrestrial plant celluloses and oven-dried chara cellulose had short nanocrystal-like morphologies of 100-300 nm in length after acid hydrolysis. In contrast, the never-dried chara cellulose had much longer microfibrils of ∼970 nm in length after acid hydrolysis. These results indicated that disordered regions present periodically along the cellulose microfibrils, which cause the formation of cellulose nanocrystals after acid hydrolysis, are not present in inherent chara cellulose microfibrils in water, but are formed artificially under drying or dehydration conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Elastin Fiber Accumulation in Liver Correlates with the Development of Hepatocellular Carcinoma.

PubMed

Yasui, Yutaka; Abe, Tokiya; Kurosaki, Masayuki; Higuchi, Mayu; Komiyama, Yasuyuki; Yoshida, Tsubasa; Hayashi, Tsuguru; Kuwabara, Konomi; Takaura, Kenta; Nakakuki, Natsuko; Takada, Hitomi; Tamaki, Nobuharu; Suzuki, Shoko; Nakanishi, Hiroyuki; Tsuchiya, Kaoru; Itakura, Jun; Takahashi, Yuka; Hashiguchi, Akinori; Sakamoto, Michiie; Izumi, Namiki

2016-01-01

The fibrosis stage, which is evaluated by the distribution pattern of collagen fibers, is a major predictor for the development of hepatocellular carcinoma (HCC) for patients with hepatitis C. Meanwhile, the role of elastin fibers has not yet been elucidated. The present study was conducted to determine the significance of quantifying both collagen and elastin fibers. We enrolled 189 consecutive patients with hepatitis C and advanced fibrosis. Using Elastica van Gieson-stained whole-slide images of pretreatment liver biopsies, collagen and elastin fibers were evaluated pixel by pixel (0.46 μm/pixel) using an automated computational method. Consequently, fiber amount and cumulative incidences of HCC within 3 years were analyzed. There was a significant correlation between collagen and elastin fibers, whereas variation in elastin fiber was greater than in collagen fiber. Both collagen fiber (p = 0.008) and elastin fiber (p < 0.001) were significantly correlated with F stage. In total, 30 patients developed HCC during follow-up. Patients who have higher elastin fiber (p = 0.002) in addition to higher collagen fiber (p = 0.05) showed significantly higher incidences of HCC. With regard to elastin fiber, this difference remained significant in F3 patients. Furthermore, for patients with a higher collagen fiber amount, higher elastin was a significant predictor for HCC development (p = 0.02). Computational analysis is a novel technique for quantification of fibers with the added value of conventional staging. Elastin fiber is a predictor for the development of HCC independently of collagen fiber and F stage.

Cues for cellular assembly of vascular elastin networks

NASA Astrophysics Data System (ADS)

Kothapalli, Chandrasekhar R.

Elastin, a structural protein distributed in the extracellular matrix of vascular tissues is critical to the maintenance of vascular mechanics, besides regulation of cell-signaling pathways involved in injury response and morphogenesis. Thus, congenital absence or disease-mediated degradation of vascular elastin and its malformation within native vessels due to innately poor elastin synthesis by adult vascular cells compromise vascular homeostasis. Current elastin regenerative strategies using tissue engineering principles are limited by the progressive destabilization of tropoelastin mRNA expression in adult vascular cells and the unavailability of scaffolds that can provide cellular cues necessary to up-regulate elastin synthesis and regenerate faithful mimics of native elastin. Since our earlier studies demonstrated the elastogenic utility of hyaluronan (HA)-based cues, we have currently sought to identify a unique set of culture conditions based on HA fragments (0.756-2000 kDa), growth factors (TGF-beta1, IGF-1) and other biomolecules (Cu2+ ions, LOX), which will together enhance synthesis, crosslinking, maturation and fibrous elastin matrix formation by adult SMCs, under both healthy and inflammatory conditions. It was observed that TGF-beta1 (1 ng/mL) together with HA oligomers (0.2 microg/mL) synergistically suppressed SMC proliferation, enhanced tropoelastin (8-fold) and matrix elastin synthesis (5.5-fold), besides improving matrix yield (4.5-fold), possibly by increasing production and activity of lysyl oxidase (LOX). Though addition of IGF-1 alone did not offer any advantage, HA fragments (20-200 kDa) in the presence of IGF-1 stimulated tropoelastin and soluble elastin synthesis more than 2.2-fold, with HMW HA contributing for ˜5-fold increase in crosslinked matrix elastin synthesis. Similarly, 0.1 M of Cu2+ ions, alone or together with HA fragments stimulated synthesis of tropoelastin (4-fold) and crosslinked matrix elastin (4.5-fold), via increases in LOX protein synthesis (2.5-fold); these cues also enhanced deposition of mature elastic fibers (˜1 mum diameter) within these cultures. Interestingly, instead of copper salt addition, even release of Cu 2+ ions (˜0.1 M) from copper nanoparticles (400 ng/mL), concurrent with HA oligomers, promoted crosslinking of elastin into mature matrix, with multiple bundles of highly-crosslinked elastin fiber formation observed (diameter ˜200-500 nm). These results strongly attest to the potential individual and combined benefits of these cues to faithful elastin matrix regeneration by healthy, patient-derived cells within tissue-engineered vascular constructs. When these cues (TGF-beta1 and HA oligomers) were added to TNF-alpha-stimulated SMC cultures, model cell culture systems mimicking phenotypically-altered cells within aneurysms, they upregulated elastin matrix production, organized elastin protein into fibers, and simultaneously stabilized this matrix by attenuating production of elastolytic enzymes. Similarly these cues also attenuated inflammatory cytokines release within cells isolated from induced-aortic aneurysms in rats, and significantly upregulated elastin synthesis and matrix formation by upregulating LOX and desmosine protein amounts. The cues were also highly effective in organizing the elastin into fibrous matrix structures mimicking the native elastin deposition process. The outcomes of this study might be of tremendous use in optimizing design of HA constructs to modulate vascular healing and matrix synthesis following revascularization, and in enabling repair of elastin networks within diseased or inflammatory (aneurysmal) adult vascular tissues.

Circulating Anti-Elastin Antibody Levels and Arterial Disease Characteristics: Associations with Arterial Stiffness and Atherosclerosis

PubMed Central

Lee, Seung-Hyun; Shin, Kihyuk; Park, Sungha; Kang, Seok-Min; Choi, Donghoon

2015-01-01

Purpose Elastin is a major arterial structural protein, and elastin-derived peptides are related to arterial change. We previously reported on a novel assay developed using aortic elastin peptides; however, its clinical implications remain unclear. In this study, we assessed whether anti-elastin antibody titers reflect the risk of coronary artery disease (CAD) or its characteristics. Materials and Methods We included 174 CAD patients and 171 age- and sex-matched controls. Anti-elastin antibody titers were quantified by enzyme-linked immunosorbent assay. Parameters of arterial stiffness, including the augmentation index (AI) and heart-to-femoral pulse wave velocity (hfPWV), were measured non-invasively. The clinical and angiographic characteristics of CAD patients were also evaluated. Associations between anti-elastin levels and vascular characteristics were examined by linear regression analysis. Results The median blood level of anti-elastin was significantly lower in the CAD group than in the controls [197 arbitrary unit (a.u.) vs. 63 a.u., p<0.001]. Levels of anti-elastin were significantly lower in men and in subjects with hypertension, diabetes mellitus, hyperlipidemia, or high hfPWV. Nevertheless, anti-elastin levels were not dependent on atherothrombotic events or the angiographic severity of CAD. In a multivariate analysis, male sex (β=-0.38, p<0.001), diabetes mellitus (β=-0.62, p<0.001), hyperlipidemia (β=-0.29, p<0.001), and AI (β=-0.006, p=0.02) were ultimately identified as determinants of anti-elastin levels. Conclusion Lower levels of anti-elastin are related to CAD. The association between antibody titers and CAD is linked to arterial stiffness rather than the advancement of atherosclerosis. PMID:26446635

Transmural variation in elastin fiber orientation distribution in the arterial wall.

PubMed

Yu, Xunjie; Wang, Yunjie; Zhang, Yanhang

2018-01-01

The complex three-dimensional elastin network is a major load-bearing extracellular matrix (ECM) component of an artery. Despite the reported anisotropic behavior of arterial elastin network, it is usually treated as an isotropic material in constitutive models. Our recent multiphoton microscopy study reported a relatively uniform elastin fiber orientation distribution in porcine thoracic aorta when imaging from the intima side (Chow et al., 2014). However it is questionable whether the fiber orientation distribution obtained from a small depth is representative of the elastin network structure in the arterial wall, especially when developing structure-based constitutive models. To date, the structural basis for the anisotropic mechanical behavior of elastin is still not fully understood. In this study, we examined the transmural variation in elastin fiber orientation distribution in porcine thoracic aorta and its association with elastin anisotropy. Using multi-photon microscopy, we observed that the elastin fibers orientation changes from a relatively uniform distribution in regions close to the luminal surface to a more circumferential distribution in regions that dominate the media, then to a longitudinal distribution in regions close to the outer media. Planar biaxial tensile test was performed to characterize the anisotropic behavior of elastin network. A new structure-based constitutive model of elastin network was developed to incorporate the transmural variation in fiber orientation distribution. The new model well captures the anisotropic mechanical behavior of elastin network under both equi- and nonequi-biaxial loading and showed improvements in both fitting and predicting capabilities when compared to a model that only considers the fiber orientation distribution from the intima side. We submit that the transmural variation in fiber orientation distribution is important in characterizing the anisotropic mechanical behavior of elastin network and should be considered in constitutive modeling of an artery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transplantation of bone marrow-derived mesenchymal stem cells expressing elastin alleviates pelvic floor dysfunction.

PubMed

Jin, Minfei; Chen, Ying; Zhou, Yun; Mei, Yan; Liu, Wei; Pan, Chenhao; Hua, Xiaolin

2016-04-05

Pelvic floor dysfunction (PFD) is a group of clinical conditions including stress urinary incontinence (SUI) and pelvic organ prolapse (POP). The abnormality of collagen and elastin metabolism in pelvic connective tissues is implicated in SUI and POP. To reconstitute the connective tissues with normal distribution of collagen and elastin, we transduced elastin to bone marrow-derived mesenchymal stem cells (BMSC). Elastin-expressing BMSCs were then differentiated to fibroblasts using bFGF, which produced collagen and elastin. To achieve the sustained release of bFGF, we formulated bFGF in poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NP). In an in vitro cell culture system of 7 days, when no additional bFGF was administrated, the initial PLGA-loaded bFGF NP induced prolonged production of collagen and elastin from elastin-expressing BMSCs. In vivo, co-injection of PLGA-loaded bFGF NP and elastin-expressing BMSCs into the PFD rats significantly improved the outcome of urodynamic tests. Together, these results provided an efficient model of connective tissue engineering using BMSC and injectable PLGA-loaded growth factors. Our results provided the first instance of a multidisciplinary approach, combining both stem cell and nanoparticle technologies, for the treatment of PFD.

Levels of circulating MMP-7 degraded elastin are elevated in pulmonary disorders.

PubMed

Kristensen, J H; Larsen, L; Dasgupta, B; Brodmerkel, C; Curran, M; Karsdal, M A; Sand, J M B; Willumsen, N; Knox, A J; Bolton, C E; Johnson, S R; Hägglund, P; Svensson, B; Leeming, D J

2015-11-01

Elastin is a signature protein of the lungs. Matrix metalloproteinase-7 (MMP-7) is important in lung defence mechanisms and degrades elastin. However, MMP-7 activity in regard to elastin degradation has never been quantified serologically in patients with lung diseases. An assay for the quantification of MMP-7 generated elastin fragments (ELM7) was therefore developed to investigate MMP-7 derived elastin degradation in pulmonary disorders such as idiopathic pulmonary fibrosis (IPF) and lung cancer. Monoclonal antibodies (mABs) were raised against eight carefully selected MMP-7 cleavage sites on elastin. After characterisation and validation of the mABs, one mAB targeting the ELM7 fragment was chosen. ELM7 fragment levels were assessed in serum samples from patients diagnosed with IPF (n=123, baseline samples, CTgov reg. NCT00786201), and lung cancer (n=40) and compared with age- and sex-matched controls. The ELM7 assay was specific towards in vitro MMP-7 degraded elastin and the ELM7 neoepitope but not towards other MMP-7 derived elastin fragments. Serum ELM7 levels were significantly increased in IPF (113%, p<0.0001) and lung cancer (96%, p<0.0001) compared to matched controls. MMP-7-generated elastin fragments can be quantified in serum and may reflect pathological lung tissue turnover in several important lung diseases. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

The mechanism of formation of Cellulose-like microfibrils in a cell-free system from Acetobacter xylinum.

PubMed

Colvin, J R

1980-07-01

The mechanism of formation of cellulose-like microfibrils by a non-soluble, particulate enzyme and uridine diphosphoglucose (UDPG) in a cell-free system from Acetobacter xylinum was studied by transmission electron microscopy and X-ray diffraction. The suspension of particles to which the enzyme is adsorbed is composed of whole, dense ovoids, 50-250 nm long when wet, of fragments of the ovoids, and amorphous substance. There is a typical unit membrane around each ovoid but initially there is no trace of fibrillar material in the suspension. When the suspension of particles is incubated with UDPG, linear wisps of fibrils are produced which associate rapidly to form longer and wider threads, especially in 0.01 M NaCl. There is no visible attachment of the wisps to the particles. After 20 min incubation, threads with the typical morphology of cellulose microfibrils are formed that later tend to become entangled in clumps. The microfibrils are insoluble in hot, aqueous, alkaline solutions and resistant to the action of trypsin, but may be degraded by glusulase. After treatment with 1 M NaOH at 100° C or with cold 18% NaOH they show an X-ray diffraction pattern which resembles that of Cellulose II from mercerized, authentic bacterial cellulose. Incorporation of radioactive glucose into the insoluble residue is enhanced by drying of the cellulose microfibrils before alkaline digestion and especially by the addition of a gross excess of carrier cellulose after incubation. In this system there is no evidence for participation of linear, axial, synthesizing sites on the cell wall of the bacterium or for ordered, organized granules in the assembly of the microfibrils. That is, cellulose-like microfibrils may be formed in a cell-free system without the action of any of the previously suggested cell organelles. In addition, these observations are consistent with a previously described notion of a transient, hydrated, nascent, bacterial cellulose microfibril. The possibility that cellulose microfibrils of green plants may be formed in the same way is considered.

Elastin Fiber Accumulation in Liver Correlates with the Development of Hepatocellular Carcinoma

PubMed Central

Kurosaki, Masayuki; Higuchi, Mayu; Komiyama, Yasuyuki; Yoshida, Tsubasa; Hayashi, Tsuguru; Kuwabara, Konomi; Takaura, Kenta; Nakakuki, Natsuko; Takada, Hitomi; Tamaki, Nobuharu; Suzuki, Shoko; Nakanishi, Hiroyuki; Tsuchiya, Kaoru; Itakura, Jun; Takahashi, Yuka; Hashiguchi, Akinori; Sakamoto, Michiie; Izumi, Namiki

2016-01-01

Background & Aims The fibrosis stage, which is evaluated by the distribution pattern of collagen fibers, is a major predictor for the development of hepatocellular carcinoma (HCC) for patients with hepatitis C. Meanwhile, the role of elastin fibers has not yet been elucidated. The present study was conducted to determine the significance of quantifying both collagen and elastin fibers. Methods We enrolled 189 consecutive patients with hepatitis C and advanced fibrosis. Using Elastica van Gieson-stained whole-slide images of pretreatment liver biopsies, collagen and elastin fibers were evaluated pixel by pixel (0.46 μm/pixel) using an automated computational method. Consequently, fiber amount and cumulative incidences of HCC within 3 years were analyzed. Results There was a significant correlation between collagen and elastin fibers, whereas variation in elastin fiber was greater than in collagen fiber. Both collagen fiber (p = 0.008) and elastin fiber (p < 0.001) were significantly correlated with F stage. In total, 30 patients developed HCC during follow-up. Patients who have higher elastin fiber (p = 0.002) in addition to higher collagen fiber (p = 0.05) showed significantly higher incidences of HCC. With regard to elastin fiber, this difference remained significant in F3 patients. Furthermore, for patients with a higher collagen fiber amount, higher elastin was a significant predictor for HCC development (p = 0.02). Conclusions Computational analysis is a novel technique for quantification of fibers with the added value of conventional staging. Elastin fiber is a predictor for the development of HCC independently of collagen fiber and F stage. PMID:27128435

Fluorescence, aggregation properties and FT-IR microspectroscopy of elastin and collagen fibers.

PubMed

Vidal, Benedicto de Campos

2014-10-01

Histological and histochemical observations support the hypothesis that collagen fibers can link to elastic fibers. However, the resulting organization of elastin and collagen type complexes and differences between these materials in terms of macromolecular orientation and frequencies of their chemical vibrational groups have not yet been solved. This study aimed to investigate the macromolecular organization of pure elastin, collagen type I and elastin-collagen complexes using polarized light DIC-microscopy. Additionally, differences and similarities between pure elastin and collagen bundles (CB) were investigated by Fourier transform-infrared (FT-IR) microspectroscopy. Although elastin exhibited a faint birefringence, the elastin-collagen complex aggregates formed in solution exhibited a deep birefringence and formation of an ordered-supramolecular complex typical of collagen chiral structure. The FT-IR study revealed elastin and CB peptide NH groups involved in different types of H-bonding. More energy is absorbed in the vibrational transitions corresponding to CH, CH2 and CH3 groups (probably associated with the hydrophobicity demonstrated by 8-anilino-1-naphtalene sulfonic acid sodium salt [ANS] fluorescence), and to νCN, δNH and ωCH2 groups of elastin compared to CB. It is assumed that the α-helix contribution to the pure elastin amide I profile is 46.8%, whereas that of the B-sheet is 20% and that unordered structures contribute to the remaining percentage. An FT-IR profile library reveals that the elastin signature within the 1360-1189cm(-1) spectral range resembles that of Conex-Toray aramid fibers. Copyright © 2014 Elsevier GmbH. All rights reserved.

Molecular-level insights into aging processes of skin elastin.

PubMed

Mora Huertas, Angela C; Schmelzer, Christian E H; Hoehenwarter, Wolfgang; Heyroth, Frank; Heinz, Andrea

2016-01-01

Skin aging is characterized by different features including wrinkling, atrophy of the dermis and loss of elasticity associated with damage to the extracellular matrix protein elastin. The aim of this study was to investigate the aging process of skin elastin at the molecular level by evaluating the influence of intrinsic (chronological aging) and extrinsic factors (sun exposure) on the morphology and susceptibility of elastin towards enzymatic degradation. Elastin was isolated from biopsies derived from sun-protected or sun-exposed skin of differently aged individuals. The morphology of the elastin fibers was characterized by scanning electron microscopy. Mass spectrometric analysis and label-free quantification allowed identifying differences in the cleavage patterns of the elastin samples after enzymatic digestion. Principal component analysis and hierarchical cluster analysis were used to visualize differences between the samples and to determine the contribution of extrinsic and intrinsic aging to the proteolytic susceptibility of elastin. Moreover, the release of potentially bioactive peptides was studied. Skin aging is associated with the decomposition of elastin fibers, which is more pronounced in sun-exposed tissue. Marker peptides were identified, which showed an age-related increase or decrease in their abundances and provide insights into the progression of the aging process of elastin fibers. Strong age-related cleavage occurs in hydrophobic tropoelastin domains 18, 20, 24 and 26. Photoaging makes the N-terminal and central parts of the tropoelastin molecules more susceptible towards enzymatic cleavage and, hence, accelerates the age-related degradation of elastin. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Defining Determinants and Dynamics and Cellulose Microfibril Biosynthesis, Assembly and Degredation OSP Number: 63079/A001

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

The central paradigm for converting plant biomass into soluble sugars for subsequent conversion to transportation fuels involves the enzymatic depolymerization of lignocellulosic plant cell walls by microbial enzymes. Despite decades of intensive research, this is still a relatively inefficient process, due largely to the recalcitrance and enormous complexity of the substrate. A major obstacle is still insufficient understanding of the detailed structure and biosynthesis of major wall components, including cellulose. For example, although cellulose is generally depicted as rigid, insoluble, uniformly crystalline microfibrils that are resistant to enzymatic degradation, the in vivo structures of plant cellulose microfibrils are surprisingly complex.more » Crystallinity is frequently disrupted, for example by dislocations and areas containing chain ends, resulting in “amorphous” disordered regions. Importantly, microfibril structure and the relative proportions of crystalline and non-crystalline disordered surface regions vary substantially and yet the molecular mechanisms by which plants regulate microfibril crystallinity, and other aspects of microfibril architecture, are still entirely unknown. This obviously has a profound effect on susceptibility to enzymatic hydrolysis and so this is a critical area of research in order to characterize and optimize cellulosic biomass degradation. The entire field of cell wall assembly, as distinct from polysaccharide biosynthesis, and the degree to which they are coupled, are relatively unexplored, despite the great potential for major advances in addressing the hurdle of biomass recalcitrance. Our overarching hypothesis was that identification of the molecular machinery that determine microfibril polymerization, deposition and structure will allow the design of more effective degradative systems, and the generation of cellulosic materials with enhanced and predictable bioconversion characteristics. Our experimental framework had been based on the idea that the most effective way to address this long standing and highly complex question is to adopt a broad ‘systems approach’. Accordingly, we assembled a multi-disciplinary collaborative team with collective expertise in plant biology and molecular genetics, polymer structure and chemistry, enzyme biochemistry and biochemical engineering. We used a spectrum of cutting edge technologies, including plant functional genomics, chemical genetics, live cell imaging, advanced microscopy, high energy X-ray spectroscopy and nanotechnology, to study the molecular determinants of cellulose microfibril structure. Importantly, this research effort was closely coupled with an analytical pipeline to characterize the effects of altering microfibril architecture on bioconversion potential, with the goal of generating predictive models to help guide the identification, development and implementation of new feedstocks. This project therefore spanned core basic science and applied research, in line with the goals of the program. Over the course of the project, accomplishments included: - Establishing platforms through reverse and forward genetics to identify and manipulate candidate genes that influence cellulose microfibril synthesis and structure in a model C3 grass, Brachypodium distachyon and a model C4 grass Setaria viridis; Identifying and characterizing the effects of a number of cellulose biosynthesis inhibitors (CBIs), and particularly those that target monocots with the aim of generating resistance loci; Developing protocols for the use of high energy X-ray diffraction (XRD) to study the structure and organization of cellulose microfibrils in plant walls, notably those in Arabidopsis and Brachypodium; Using the chemical and genetic based inhibition strategies to develop new mechanistic models of cellulose microfibril crystallization, and of how altering microfibril architecture influences digestibility.« less

Exploring the Nature of Cellulose Microfibrils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Ying; Burger, Christian; Ma, Hongyang

2015-03-20

Ultrathin cellulose microfibril fractions were extracted from spruce wood powder using combined delignification, TEMPO-catalyzed oxidation, and sonication processes. Small-angle X-ray scattering of these microfibril fractions in a “dilute” aqueous suspension (concentration 0.077 wt %) revealed that their shape was in the form of nanostrip with 4 nm width and only about 0.5 nm thicknesses. We found that these dimensions were further confirmed by TEM and AFM measurements. The 0.5 nm thickness implied that the nanostrip could contain only a single layer of cellulose chains. At a higher concentration (0.15 wt %), SAXS analysis indicated that these nanostrips aggregated into amore » layered structure. The X-ray diffraction of samples collected at different preparation stages suggested that microfibrils were delaminated along the (110) planes from the Iβ cellulose crystals. Moreover, the degree of oxidation and solid-state 13C NMR characterizations indicated that, in addition to the surface molecules, some inner molecules of microfibrils were also oxidized, facilitating the delamination into cellulose nanostrips.« less

Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose.

PubMed

Saito, Tsuguyuki; Nishiyama, Yoshiharu; Putaux, Jean-Luc; Vignon, Michel; Isogai, Akira

2006-06-01

Never-dried native celluloses (bleached sulfite wood pulp, cotton, tunicin, and bacterial cellulose) were disintegrated into individual microfibrils after oxidation mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical followed by a homogenizing mechanical treatment. When oxidized with 3.6 mmol of NaClO per gram of cellulose, almost the totality of sulfite wood pulp and cotton were readily disintegrated into long individual microfibrils by a treatment with a Waring Blendor, yielding transparent and highly viscous suspensions. When observed by transmission electron microscopy, the wood pulp and cotton microfibrils exhibited a regular width of 3-5 nm. Tunicin and bacterial cellulose could be disintegrated by sonication. A bulk degree of oxidation of about 0.2 per one anhydroglucose unit of cellulose was necessary for a smooth disintegration of sulfite wood pulp, whereas only small amounts of independent microfibrils were obtained at lower oxidation levels. This limiting degree of oxidation decreased in the following order: sulfite wood pulp > cotton > bacterial cellulose, tunicin.

Exploring the nature of cellulose microfibrils.

PubMed

Su, Ying; Burger, Christian; Ma, Hongyang; Chu, Benjamin; Hsiao, Benjamin S

2015-04-13

Ultrathin cellulose microfibril fractions were extracted from spruce wood powder using combined delignification, TEMPO-catalyzed oxidation, and sonication processes. Small-angle X-ray scattering of these microfibril fractions in a "dilute" aqueous suspension (concentration 0.077 wt %) revealed that their shape was in the form of nanostrip with 4 nm width and only about 0.5 nm thicknesses. These dimensions were further confirmed by TEM and AFM measurements. The 0.5 nm thickness implied that the nanostrip could contain only a single layer of cellulose chains. At a higher concentration (0.15 wt %), SAXS analysis indicated that these nanostrips aggregated into a layered structure. The X-ray diffraction of samples collected at different preparation stages suggested that microfibrils were delaminated along the (11̅0) planes from the Iβ cellulose crystals. The degree of oxidation and solid-state (13)C NMR characterizations indicated that, in addition to the surface molecules, some inner molecules of microfibrils were also oxidized, facilitating the delamination into cellulose nanostrips.

The relation of apple texture with cell wall nanostructure studied using an atomic force microscope.

PubMed

Cybulska, Justyna; Zdunek, Artur; Psonka-Antonczyk, Katarzyna M; Stokke, Bjørn T

2013-01-30

In this study, the relation of the nanostructure of cell walls with their texture was investigated for six different apple cultivars. Cell wall material (CWM) and cellulose microfibrils were imaged by atomic force microscope (AFM). The mean diameter of cellulose microfibrils for each cultivar was estimated based on the AFM height topographs obtained using the tapping mode of dried specimens. Additionally, crystallinity of cellulose microfibrils and pectin content was determined. Texture of apple cultivars was evaluated by sensory and instrumental analysis. Differences in cellulose diameter as determined from the AFM height topographs of the nanostructure of cell walls of the apple cultivars are found to relate to the degree of crystallinity and pectin content. Cultivars with thicker cellulose microfibrils also revealed crisper, harder and juicier texture, and greater acoustic emission. The data suggest that microfibril thickness affects the mechanical strength of cell walls which has consequences for sensory and instrumental texture. Copyright © 2012 Elsevier Ltd. All rights reserved.

Glucose Suppresses Biological Ferroelectricity in Aortic Elastin

PubMed Central

Liu, Yuanming; Wang, Yunjie; Chow, Ming-Jay; Chen, Nataly Q.; Ma, Feiyue; Zhang, Yanhang; Li, Jiangyu

2013-01-01

Elastin is an intriguing extracellular matrix protein present in all connective tissues of vertebrates, rendering essential elasticity to connective tissues subjected to repeated physiological stresses. Using piezoresponse force microscopy, we show that the polarity of aortic elastin is switchable by an electrical field, which may be associated with the recently discovered biological ferroelectricity in the aorta. More interestingly, it is discovered that the switching in aortic elastin is largely suppressed by glucose treatment, which appears to freeze the internal asymmetric polar structures of elastin, making it much harder to switch, or suppressing the switching completely. Such loss of ferroelectricity could have important physiological and pathological implications from aging to arteriosclerosis that are closely related to glycation of elastin. PMID:23679639

Cyclic Nucleotide-gated Channel α-3 (CNGA3) Interacts with Stereocilia Tip-Link Cadherin 23 + Exon 68 or Alternatively with Myosin VIIa, Two Proteins Required for Hair Cell Mechanotransduction*

PubMed Central

Selvakumar, Dakshnamurthy; Drescher, Marian J.; Drescher, Dennis G.

2013-01-01

Previously, we obtained evidence for a photoreceptor/olfactory type of CNGA3 transcript in a purified teleost vestibular hair cell preparation with immunolocalization of CNGA3 protein to stereocilia of teleost vestibular and mammalian cochlear hair cells. The carboxyl terminus of highly Ca2+-permeable CNGA3 expressed in the mammalian organ of Corti and saccular hair cells was found to interact with an intracellular domain of microfibril interface-located protein 1 (EMILIN 1), a member of the elastin superfamily, also immunolocalizd to hair cell stereocilia (Selvakumar, D., Drescher, M. J., Dowdall, J. R., Khan, K. M., Hatfield, J. S., Ramakrishnan, N. A., and Drescher, D. G. (2012) Biochem. J. 443, 463–476). Here, we provide evidence for organ of Corti proteins, of Ca2+-dependent binding of the amino terminus of CNGA3 specifically to the carboxyl terminus of stereocilia tip-link protein CDH23 +68 (cadherin 23 with expressed exon 68) by yeast two-hybrid mating and co-transformation protocols, pulldown assays, and surface plasmon resonance analysis. Myosin VIIa, required for adaptation of hair cell mechanotransduction (MET) channel(s), competed with CDH23 +68, with direct Ca2+-dependent binding to the amino terminus of CNGA3. Based upon the premise that hair cell stereocilia tip-link proteins are closely coupled with MET, these results are consistent with the possibility that CNGA3 participates in hair-cell MET. Together with the demonstration of protein-protein interaction between HCN1 and tip-link protein protocadherin 15 CD3 (Ramakrishnan, N. A., Drescher, M. J., Barretto, R. L., Beisel, K. W., Hatfield, J. S., and Drescher, D. G. (2009) J. Biol. Chem. 284, 3227–3238; Ramakrishnan, N. A., Drescher, M. J., Khan, K. M., Hatfield, J. S., and Drescher, D. G. (2012) J. Biol. Chem. 287, 37628–37646), a protein-protein interaction for CNGA3 and a second tip-link protein, CDH23 +68, further suggests possible association of two different channels with a single stereocilia tip link. PMID:23329832

Cyclic nucleotide-gated channel α-3 (CNGA3) interacts with stereocilia tip-link cadherin 23 + exon 68 or alternatively with myosin VIIa, two proteins required for hair cell mechanotransduction.

PubMed

Selvakumar, Dakshnamurthy; Drescher, Marian J; Drescher, Dennis G

2013-03-08

Previously, we obtained evidence for a photoreceptor/olfactory type of CNGA3 transcript in a purified teleost vestibular hair cell preparation with immunolocalization of CNGA3 protein to stereocilia of teleost vestibular and mammalian cochlear hair cells. The carboxyl terminus of highly Ca(2+)-permeable CNGA3 expressed in the mammalian organ of Corti and saccular hair cells was found to interact with an intracellular domain of microfibril interface-located protein 1 (EMILIN 1), a member of the elastin superfamily, also immunolocalizd to hair cell stereocilia (Selvakumar, D., Drescher, M. J., Dowdall, J. R., Khan, K. M., Hatfield, J. S., Ramakrishnan, N. A., and Drescher, D. G. (2012) Biochem. J. 443, 463-476). Here, we provide evidence for organ of Corti proteins, of Ca(2+)-dependent binding of the amino terminus of CNGA3 specifically to the carboxyl terminus of stereocilia tip-link protein CDH23 +68 (cadherin 23 with expressed exon 68) by yeast two-hybrid mating and co-transformation protocols, pulldown assays, and surface plasmon resonance analysis. Myosin VIIa, required for adaptation of hair cell mechanotransduction (MET) channel(s), competed with CDH23 +68, with direct Ca(2+)-dependent binding to the amino terminus of CNGA3. Based upon the premise that hair cell stereocilia tip-link proteins are closely coupled with MET, these results are consistent with the possibility that CNGA3 participates in hair-cell MET. Together with the demonstration of protein-protein interaction between HCN1 and tip-link protein protocadherin 15 CD3 (Ramakrishnan, N. A., Drescher, M. J., Barretto, R. L., Beisel, K. W., Hatfield, J. S., and Drescher, D. G. (2009) J. Biol. Chem. 284, 3227-3238; Ramakrishnan, N. A., Drescher, M. J., Khan, K. M., Hatfield, J. S., and Drescher, D. G. (2012) J. Biol. Chem. 287, 37628-37646), a protein-protein interaction for CNGA3 and a second tip-link protein, CDH23 +68, further suggests possible association of two different channels with a single stereocilia tip link.

Mechanical Properties Versus Morphology of Ordered Polymers. Volume 6

DTIC Science & Technology

1986-06-01

of PBT fiber was examined by TEM of epoxy impregnated fibers. An oriented network of microfibrils with typical fibril diameters of about 80-100A was...observed. We suggest that these microfibrils are the fundamental structural elements of the fiber. Thus knowledge of the mechanism by which this initial...benzobisthiazole) fiber was examined by transmission electron 1 microscopy of epoxy impregnated fibers. An oriented network of microfibrils with typical

ELASTIN: DIMINISHED REACTIVITY WITH ALDEHYDE REAGENTS IN COPPER DEFICIENCY AND LATHYRISM

PubMed Central

Miller, E. J.; Fullmer, Harold M.

1966-01-01

Elastin fibers in the aortas of control, lathyritic, copper-supplemented, and copper-deficient chicks were examined histochemically and chemically for aldehyde content. Diminished staining for aldehydes was obtained in the fibers from the aortas of lathyritic and copper-deficient chicks. Chemical studies of elastin isolated from the aortas of control and lathyritic chicks showed an apparent loss of lysine residues in control elastin to be associated with an increase in aldehyde content providing evidence that lysine is converted to an aldehyde-containing intermediate during biosynthesis of desmosine and isodesmosine. Approximately 6 aldehyde groups were present for every 1000 amino acids in elastin isolated from the aortas of control animals, while the corresponding number in lathyritic elastin was 4. At least two types of aldehydes, saturated and α,β-unsaturated, appear to be associated with elastin, suggesting the presence of more than one intermediate between lysine and the desmosines. PMID:5941783

Probing crystal structure and mesoscale assembly of cellulose microfibrils in plant cell walls, tunicate tests, and bacterial films using vibrational sum frequency generation (SFG) spectroscopy.

PubMed

Lee, Christopher M; Kafle, Kabindra; Park, Yong Bum; Kim, Seong H

2014-06-14

This study reports that the noncentrosymmetry and phase synchronization requirements of the sum frequency generation (SFG) process can be used to distinguish the three-dimensional organization of crystalline cellulose distributed in amorphous matrices. Crystalline cellulose is produced as microfibrils with a few nanometer diameters by plants, tunicates, and bacteria. Crystalline cellulose microfibrils are embedded in wall matrix polymers and assembled into hierarchical structures that are precisely designed for specific biological and mechanical functions. The cellulose microfibril assemblies inside cell walls are extremely difficult to probe. The comparison of vibrational SFG spectra of uniaxially-aligned and disordered films of cellulose Iβ nanocrystals revealed that the spectral features cannot be fully explained with the crystallographic unit structure of cellulose. The overall SFG intensity, the alkyl peak shape, and the alkyl/hydroxyl intensity ratio are sensitive to the lateral packing and net directionality of the cellulose microfibrils within the SFG coherence length scale. It was also found that the OH SFG stretch peaks could be deconvoluted to find the polymorphic crystal structures of cellulose (Iα and Iβ). These findings were used to investigate the cellulose crystal structure and mesoscale cellulose microfibril packing in intact plant cell walls, tunicate tests, and bacterial films.

The assembly of cellulose microfibrils in Valonia macrophysa Kütz.

PubMed

Itoh, T; Brown, R M

1984-03-01

The assembly of cellulose microfibrils was investigated in artificially induced protoplasts of the alga, Valonia macrophysa (Siphonocladales). Primary-wall microfibrills, formed within 72 h of protoplast induction, are randomly oriented. Secondary-wall lamellae, which are produced within 96 h after protoplast induction, have more than three orientations of highly ordered microfibrils. The innermost, recently deposited micofibrils are not parallel with the cortical microtubules, thus indicating a more indirect role of microtubules in the orientation of microfibrils. Fine filamentous structures with a periodicity of 5.0-5.5 nm and the dimensions of actin were observed adjacent to the plasma membrane. Linear cellulose-terminal synthesizing complexes (TCs) consisting of three rows, each with 30-40 particles, were observed not only on the E fracture (EF) but also on P fracture (PF) faces of the plasma membrane. The TC appears to span both faces of the bimolecular leaflet. The average length of the TC is 350 nm, and the number of TCs per unit area during primary-wall synthesis is 1 per μm(2). Neither paired TCs nor granule bands characteristic of Oocystis were observed. Changes in TC structure and distribution during the conversion from primary- to secondary-wall formation have been described. Cellulose microfibril assembly in Valonia is discussed in relation to the process among other eukaryotic systems.

Phase separation and mechanical properties of an elastomeric biomaterial from spider wrapping silk and elastin block copolymers.

PubMed

Muiznieks, Lisa D; Keeley, Fred W

2016-10-01

Elastin and silk spidroins are fibrous, structural proteins with elastomeric properties of extension and recoil. While elastin is highly extensible and has excellent recovery of elastic energy, silks are particularly strong and tough. This study describes the biophysical characterization of recombinant polypeptides designed by combining spider wrapping silk and elastin-like sequences as a strategy to rationally increase the strength of elastin-based materials while maintaining extensibility. We demonstrate a thermo-responsive phase separation and spontaneous colloid-like droplet formation from silk-elastin block copolymers, and from a 34 residue disordered region of Argiope trifasciata wrapping silk alone, and measure a comprehensive suite of tensile mechanical properties from cross-linked materials. Silk-elastin materials exhibited significantly increased strength, toughness, and stiffness compared to an elastin-only material, while retaining high failure strains and low energy loss upon recoil. These data demonstrate the mechanical tunability of protein polymer biomaterials through modular, chimeric recombination, and provide structural insights into mechanical design. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 693-703, 2016. © 2016 Wiley Periodicals, Inc.

Modeling of the morphological change of cellulose microfibrils caused with aqueous NaOH solution: the longitudinal contraction and laterally swelling during decrystallization.

PubMed

Nakano, Takato

2017-04-01

The conformation of cellulose microfibrils treated with aqueous NaOH was modeled as partially decrystallized cellulose chains before completing conversion to cellulose II, in order to elucidate the change in morphology of ramie fiber caused by NaOH treatment. Equations for the relative length and width of the microfibrils were derived on the basis of partially decrystallized microfibrils modeling. Each equation contains four parameters, n, β, w c , and c r , which correspond to the number of glucose residues between periodic defects along the untreated ramie cellulose microfibrils, the extension ratio of amorphous cellulose chain along length, the cross-section crystallinity, and the correction term of crystallinity, respectively. The validity of the derived equations was confirmed by two types of simulations. One is performed using experimental data L/L 0 and W/W 0 as a function of crystallinity, while the other is done using the relationship between the relative length and width obtained from the experimental data, which is independent of crystallinity, was performed. The best-fit simulation was obtained under n = 277, β = 2.813, and c r w c  = 0.671 for the former and under n = 301 and β = 2.792 for the latter. These values of n and β correspond closely to the values reported in references for ramie microfibrils. Both simulation results show that macroscopic changes in the morphology of ramie fibers is attributable to the changes in cellulose chain conformation in the decrystallized regions created along the microfibrils upon NaOH treatment.

Disorganization of Cortical Microtubules Stimulates Tangential Expansion and Reduces the Uniformity of Cellulose Microfibril Alignment among Cells in the Root of Arabidopsis1

PubMed Central

Baskin, Tobias I.; Beemster, Gerrit T.S.; Judy-March, Jan E.; Marga, Françoise

2004-01-01

To test the role of cortical microtubules in aligning cellulose microfibrils and controlling anisotropic expansion, we exposed Arabidopsis thaliana roots to moderate levels of the microtubule inhibitor, oryzalin. After 2 d of treatment, roots grow at approximately steady state. At that time, the spatial profiles of relative expansion rate in length and diameter were quantified, and roots were cryofixed, freeze-substituted, embedded in plastic, and sectioned. The angular distribution of microtubules as a function of distance from the tip was quantified from antitubulin immunofluorescence images. In alternate sections, the overall amount of alignment among microfibrils and their mean orientation as a function of position was quantified with polarized-light microscopy. The spatial profiles of relative expansion show that the drug affects relative elongation and tangential expansion rates independently. The microtubule distributions averaged to transverse in the growth zone for all treatments, but on oryzalin the distributions became broad, indicating poorly organized arrays. At a subcellular scale, cellulose microfibrils in oryzalin-treated roots were as well aligned as in controls; however, the mean alignment direction, while consistently transverse in the controls, was increasingly variable with oryzalin concentration, meaning that microfibril orientation in one location tended to differ from that of a neighboring location. This conclusion was confirmed by direct observations of microfibrils with field-emission scanning electron microscopy. Taken together, these results suggest that cortical microtubules ensure microfibrils are aligned consistently across the organ, thereby endowing the organ with a uniform mechanical structure. PMID:15299138

Polyphenol-Stabilized Tubular Elastin Scaffolds for Tissue Engineered Vascular Grafts

PubMed Central

Chuang, Ting-Hsien; Stabler, Christopher; Simionescu, Agneta

2009-01-01

Tissue-engineered vascular grafts require elastic, acellular porous scaffolds with controlled biodegradability and properties matching those of natural arteries. Elastin would be a desirable component for such applications, but elastin does not easily regenerate experimentally. Our approach is to develop tubular elastin scaffolds using decellularization and removal of collagen from porcine carotid arteries (∼5 mm diameter) using alkaline extraction. Because elastin is susceptible to rapid degeneration after implantation, scaffolds were further treated with penta-galloyl glucose (PGG), an established polyphenolic elastin-stabilizing agent. Scaffolds were compared in vitro with detergent-decellularized arteries for structure, composition, resistance to degradation, mechanical properties, and cytotoxicity and in vivo for cell infiltration and remodeling potential. Results showed effective decellularization and almost complete collagen removal by alkaline extraction. PGG-treated elastin scaffolds proved to be resistant to elastase digestion in vitro, maintained their cylindrical shapes, showed high resistance to burst pressures, and supported growth of endothelial cells and fibroblasts. In vivo results showed that PGG treatment reduced the rate of elastin biodegradation and controlled cell infiltration but did not hamper new collagen and proteoglycan deposition and secretion of matrix-degrading proteases. Alkali-purified, PGG-treated tubular arterial elastin scaffolds exhibit many desirable properties to be recommended for clinical applications as vascular grafts. PMID:19254115

Degree of polymerization of glucan chains shapes the structure fluctuations and melting thermodynamics of a cellulose microfibril.

PubMed

Chang, Rakwoo; Gross, Adam S; Chu, Jhih-Wei

2012-07-19

A Staggered LATtice (SLAT) model is developed for modeling cellulose microfibrils. The simple representation of molecular packing and interactions employed in SLAT allows simulations of structure fluctuations and phase transition of cellulose microfibrils at sufficiently long and large scales for comparison with experiments. Glucan chains in the microfibril are modeled as connected monomers, each corresponding to a cellobiose subunit, and the surrounding space around the cellulose is composed of solvent cells. Interaction parameters of monomer-monomer interactions were parametrized based on the results of atomistic molecular dynamics simulations. The monomer-solvent interaction was optimized to give a melting temperature of ∼695 K for the 36-glucan chain model cellulose microfibril, which is consistent with the estimation based on experimental data. Monte Carlo simulations of the SLAT model also capture experimentally measured X-ray diffraction patterns of cellulose as a function of temperature, including the region of melting transition, as well as predict the highly flexible regions in the microfibril. Beyond the diameter of ∼3 nm, we found that melting temperature of the cellulose microfibril is not significantly shifted by changing the thickness. On the other hand, a slight decrease in the degree of polymerization of glucan chains is shown to enhance structure fluctuations through the ends of glucan chains, i.e., the defect sites, and thereby significantly reduce the melting temperature. Analysis of the sizes, densities, and lifetimes of defect structures in the microfibril indicates a significant extent of fluctuations on the surfaces even at room temperature and that defect statistics are strong but distinct functions of temperature and solvent quality. The SLAT model is the first of its kind for simulating cellulosic materials, and this work shows that it can be used to incorporate information obtained from atomistic simulations and experimental data to enable the aforementioned findings through computation.

Defining the hierarchical organisation of collagen VI microfibrils at nanometre to micrometre length scales.

PubMed

Godwin, Alan R F; Starborg, Tobias; Sherratt, Michael J; Roseman, Alan M; Baldock, Clair

2017-04-01

Extracellular matrix microfibrils are critical components of connective tissues with a wide range of mechanical and cellular signalling functions. Collagen VI is a heteromeric network-forming collagen which is expressed in tissues such as skin, lung, blood vessels and articular cartilage where it anchors cells into the matrix allowing for transduction of biochemical and mechanical signals. It is not understood how collagen VI is arranged into microfibrils or how these microfibrils are arranged into tissues. Therefore we have characterised the hierarchical organisation of collagen VI across multiple length scales. The frozen hydrated nanostructure of purified collagen VI microfibrils was reconstructed using cryo-TEM. The bead region has a compact hollow head and flexible tail regions linked by the collagenous interbead region. Serial block face SEM imaging coupled with electron tomography of the pericellular matrix (PCM) of murine articular cartilage revealed that the PCM has a meshwork-like organisation formed from globular densities ∼30nm in diameter. These approaches can characterise structures spanning nanometer to millimeter length scales to define the nanostructure of individual collagen VI microfibrils and the micro-structural organisation of these fibrils within tissues to help in the future design of better mimetics for tissue engineering. Cartilage is a connective tissue rich in extracellular matrix molecules and is tough and compressive to cushion the bones of joints. However, in adults cartilage is poorly repaired after injury and so this is an important target for tissue engineering. Many connective tissues contain collagen VI, which forms microfibrils and networks but we understand very little about these assemblies or the tissue structures they form. Therefore, we have use complementary imaging techniques to image collagen VI microfibrils from the nano-scale to the micro-scale in order to understand the structure and the assemblies it forms. These findings will help to inform the future design of scaffolds to mimic connective tissues in regenerative medicine applications. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Brachytherapy Using Elastin-Like Polypeptides with (131)I Inhibit Tumor Growth in Rabbits with VX2 Liver Tumor.

PubMed

Liu, Xinpei; Shen, Yiming; Zhang, Xuqian; Lin, Rui; Jia, Qiang; Chang, Yixiang; Liu, Wenge; Liu, Wentian

2016-10-01

Brachytherapy is a targeted type of radiotherapy utilized in the treatment of cancers. Elastin-like polypeptides are a unique class of genetically engineered peptide polymers that have several attractive properties for brachytherapy. To explore the feasibility and application of brachytherapy for VX2 liver tumor using elastin-like polypeptides with (131)I so as to provide reliable experimental evidence for a new promising treatment of liver cancer. Elastin-like polypeptide as carrier was labeled with (131)I using the iodogen method. Ten eligible rabbits with VX2 liver tumor were randomly divided into the treatment group (n = 5) and control group (n = 5). The treatment group received brachytherapy using elastin-like polypeptide with (131)I, and in the control group, elastin-like polypeptide was injected into the VX2 liver tumor as a control. Periodic biochemical and imaging surveillances were required to assess treatment efficacy. The stability of elastin-like polypeptide with (131)I in vitro was maintained at over 96.8 % for 96 h. Biochemistry and imaging indicated brachytherapy using elastin-like polypeptide with (131)I for liver tumor can improve liver function and inhibit tumor growth (P < 0.05). Elastin-like polypeptide can be an ideal carrier of (131)I and have high labeling efficiency, radiochemical purity and stability. Brachytherapy using elastin-like polypeptide with (131)I for liver tumor is a useful therapy that possesses high antitumor efficacy advantages.

Prolyl hydroxylation in elastin is not random.

PubMed

Schmelzer, Christian E H; Nagel, Marcus B M; Dziomba, Szymon; Merkher, Yulia; Sivan, Sarit S; Heinz, Andrea

2016-10-01

This study aimed to investigate the prolyl and lysine hydroxylation in elastin from different species and tissues. Enzymatic digests of elastin samples from human, cattle, pig and chicken were analyzed using mass spectrometry and bioinformatics tools. It was confirmed at the protein level that elastin does not contain hydroxylated lysine residues regardless of the species. In contrast, prolyl hydroxylation sites were identified in all elastin samples. Moreover, the analysis of the residues adjacent to prolines allowed the determination of the substrate site preferences of prolyl 4-hydroxylase. It was found that elastins from all analyzed species contain hydroxyproline and that at least 20%-24% of all proline residues were partially hydroxylated. Determination of the hydroxylation degrees of specific proline residues revealed that prolyl hydroxylation depends on both the species and the tissue, however, is independent of age. The fact that the highest hydroxylation degrees of proline residues were found for elastin from the intervertebral disc and knowledge of elastin arrangement in this tissue suggest that hydroxylation plays a biomechanical role. Interestingly, a proline-rich domain of tropoelastin (domain 24), which contains several repeats of bioactive motifs, does not show any hydroxyproline residues in the mammals studied. The results show that prolyl hydroxylation is not a coincidental feature and may contribute to the adaptation of the properties of elastin to meet the functional requirements of different tissues. The study for the first time shows that prolyl hydroxylation is highly regulated in elastin. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of glucose on the biomechanical function of arterial elastin

PubMed Central

Wang, Yunjie; Zeinali-Davarani, Shahrokh; Davis, Elaine C.; Zhang, Yanhang

2015-01-01

Elastin is essential to provide elastic support for blood vessels. As a remarkably long-lived protein, elastin can suffer from cumulative effects of exposure to biochemical damages, which can greatly compromise its biomechanical properties. Non-enzymatic glycation is one of the main mechanisms of aging and its effect is magnified in diabetic patients. The purpose of this study is to investigate the effects of glucose on mechanical properties of isolated porcine aortic elastin. Elastin samples were incubated in 2 M glucose solution and were allowed to equilibrate for 4, 7, 14, 21 or 28 days at 37°C. Equibiaxial tensile tests were performed to study the changes of elastic properties of elastin due to glycation. Significant decreases in tissue dimension were observed after 7 days glucose incubation. Elastin samples treated for 14, 21 or 28 days demonstrate a significant increase in hysteresis in the stress-stretch curves, indicating a greater energy loss due to glucose treatment. Both the longitudinal and the circumferential directions show significant increases in tangent modulus with glucose treatment, however only significant increases are observed after 7 days for the circumferential direction. An eight-chain statistical mechanics based microstructural model was used to study the hyperelastic and orthotropic behavior of the glucose-treated elastin and the material parameters were estimated using a nonlinear least squares method. Material parameters in the model were related to elastin density and fiber orientation, and, hence, the possible microstructural changes in glucose-treated elastin. Estimated material parameters show a general increasing trend in elastin density per unit volume with glucose incubation. The simulation results also indicate that more elastic fibers are aligned in the longitudinal and circumferential directions, rather than in the radial direction. PMID:26042769

Effect of glucose on the biomechanical function of arterial elastin.

PubMed

Wang, Yunjie; Zeinali-Davarani, Shahrokh; Davis, Elaine C; Zhang, Yanhang

2015-09-01

Elastin is essential to provide elastic support for blood vessels. As a remarkably long-lived protein, elastin can suffer from cumulative effects of exposure to biochemical damages, which can greatly compromise its biomechanical properties. Non-enzymatic glycation is one of the main mechanisms of aging and its effect is magnified in diabetic patients. The purpose of this study is to investigate the effects of glucose on mechanical properties of isolated porcine aortic elastin. Elastin samples were incubated in 2 M glucose solution and were allowed to equilibrate for 4, 7, 14, 21 or 28 days at 37 °C. Equibiaxial tensile tests were performed to study the changes of elastic properties of elastin due to glycation. Significant decreases in tissue dimension were observed after 7 days glucose incubation. Elastin samples treated for 14, 21 or 28 days demonstrate a significant increase in hysteresis in the stress-stretch curves, indicating a greater energy loss due to glucose treatment. Both the longitudinal and the circumferential directions show significant increases in tangent modulus with glucose treatment, however only significant increases are observed after 7 days for the circumferential direction. An eight-chain statistical mechanics based microstructural model was used to study the hyperelastic and orthotropic behavior of the glucose-treated elastin and the material parameters were estimated using a nonlinear least squares method. Material parameters in the model were related to elastin density and fiber orientation, and, hence, the possible microstructural changes in glucose-treated elastin. Estimated material parameters show a general increasing trend in elastin density per unit volume with glucose incubation. The simulation results also indicate that more elastic fibers are aligned in the longitudinal and circumferential directions, rather than in the radial direction. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Axial Compressive Strength of High Performance Polymer Fibers

DTIC Science & Technology

1985-03-01

consists of axially oriented graphitic microfibrils that have the strong and stiff graphite crystal basal plane oriented parallel to the long axis of the... microfibrils [3,4]. The synthetic rigid polymer fibers are represented by only one commercial material: the PPTA fibers produced by E.I. DuPont de...and/or microfibrils is presented. A potential energy balance analysis is used to calculate critical stresses for the onset of compressive buckling

Elastin governs the mechanical response of medial collateral ligament under shear and transverse tensile loading.

PubMed

Henninger, Heath B; Valdez, William R; Scott, Sara A; Weiss, Jeffrey A

2015-10-01

Elastin is a highly extensible structural protein network that provides near-elastic resistance to deformation in biological tissues. In ligament, elastin is localized between and along the collagen fibers and fascicles. When ligament is stretched along the primary collagen axis, elastin supports a relatively high percentage of load. We hypothesized that elastin may also provide significant load support under elongation transverse to the primary collagen axis and shear along the collagen axis. Quasi-static transverse tensile and shear material tests were performed to quantify the mechanical contributions of elastin during deformation of porcine medial collateral ligament. Dose response studies were conducted to determine the level of elastase enzymatic degradation required to produce a maximal change in the mechanical response. Maximal changes in peak stress occurred after 3h of treatment with 2U/ml porcine pancreatic elastase. Elastin degradation resulted in a 60-70% reduction in peak stress and a 2-3× reduction in modulus for both test protocols. These results demonstrate that elastin provides significant resistance to elongation transverse to the collagen axis and shear along the collagen axis while only constituting 4% of the tissue dry weight. The magnitudes of the elastin contribution to peak transverse and shear stress were approximately 0.03 MPa, as compared to 2 MPa for axial tensile tests, suggesting that elastin provides a highly anisotropic contribution to the mechanical response of ligament and is the dominant structural protein resisting transverse and shear deformation of the tissue. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The influence of angiotensin-converting enzyme inhibitors on the aorta elastin metabolism in diet-induced hypercholesterolaemia in rabbits.

PubMed

Wojakowski, W; Gminski, J; Siemianowicz, K; Goss, M; Machalski, M

2001-03-01

Aortic elastin turnover is significantly accelerated in atherosclerosis, partly because of activation of the renin-angiotensin-aldosterone system caused by hypercholesterolaemia. We postulated that angiotensin-converting enzyme inhibitors (ACE-I) prevent the aortic elastin loss in experimental hypercholesterolaemia. Two doses of ACE-I (captopril, enalapril and quinapril) were used: a dose equivalent to that applied to human subjects and a dose 10 times higher. We found that the increase in serum and aortic elastolytic activity in cholesterol-fed rabbits was prevented by high-dose captopril. The elastin content in aorta homogenates from cholesterol-fed rabbits was significantly decreased. The higher dose of captopril, but no other ACE-I, prevented this decrease in aortic elastin content. In cholesterol-fed rabbits the elastin-bound calcium content was significantly elevated. The higher doses of captopril and enalapril lowered the elastin-bound calcium content. In serum and aortic homogenates of cholesterol-fed rabbits, ACE activity was elevated by 15% and 77%, respectively. Both doses of captopril, enalapril and quinapril prevented this cholesterol-induced increase in serum and aortic ACE activity. We conclude that: 1) administration of captopril at doses 10 times higher than those used in humans prevents hypercholesterolaemia increased aortic elastin loss. 2) higher doses of captopril and enalapril prevent the hypercholesterolaemia-induced increase in aortic elastin-bound calcium.

Effect of Elastin Digestion on the Quasi-static Tensile Response of Medial Collateral Ligament

PubMed Central

Henninger, Heath B.; Underwood, Clayton J.; Romney, Steven J.; Davis, Grant L.; Weiss, Jeffrey A.

2014-01-01

Elastin is a structural protein that provides resilience to biological tissues. We examined the contributions of elastin to the quasi-static tensile response of porcine medial collateral ligament through targeted disruption of the elastin network with pancreatic elastase. Elastase concentration and treatment time were varied to determine a dose response. Whereas elastin content decreased with increasing elastase concentration and treatment time, the change in peak stress after cyclic loading reached a plateau above 1 U/ml elastase and 6 hr treatment. For specimens treated with 2 U/ml elastase for 6 hr, elastin content decreased approximately 35%. Mean peak tissue strain after cyclic loading (4.8%, p≥0.300), modulus (275 MPa, p≥0.114) and hysteresis (20%, p≥0.553) were unaffected by elastase digestion, but stress decreased significantly after treatment (up to 2 MPa, p≤0.049). Elastin degradation had no effect on failure properties, but tissue lengthened under the same pre-stress. Stiffness in the linear region was unaffected by elastase digestion, suggesting that enzyme treatment did not disrupt collagen. These results demonstrate that elastin primarily functions in the toe region of the stress-strain curve, yet contributes load support in the linear region. The increase in length after elastase digestion suggests that elastin may pre-stress and stabilize collagen crimp in ligaments. PMID:23553827

Neutrophil elastase-induced elastin degradation mediates macrophage influx and lung injury in 60% O2-exposed neonatal rats.

PubMed

Masood, Azhar; Yi, Man; Belcastro, Rosetta; Li, Jun; Lopez, Lianet; Kantores, Crystal; Jankov, Robert P; Tanswell, A Keith

2015-07-01

Neutrophil (PMNL) influx precedes lung macrophage (LM) influx into the lung following exposure of newborn pups to 60% O2. We hypothesized that PMNL were responsible for the signals leading to LM influx. This was confirmed when inhibition of PMNL influx with a CXC chemokine receptor-2 antagonist, SB-265610, also prevented the 60% O2-dependent LM influx, LM-derived nitrotyrosine formation, and pruning of small arterioles. Exposure to 60% O2 was associated with increased lung contents of neutrophil elastase and α-elastin, a marker of denatured elastin, and a decrease in elastin fiber density. This led us to speculate that neutrophil elastase-induced elastin fragments were the chemokines that led to a LM influx into the 60% O2-exposed lung. Inhibition of neutrophil elastase with sivelestat or elafin attenuated the LM influx. Sivelestat also attenuated the 60% O2-induced decrease in elastin fiber density. Daily injections of pups with an antibody to α-elastin prevented the 60% O2-dependent LM influx, impaired alveologenesis, and impaired small vessel formation. This suggests that neutrophil elastase inhibitors may protect against neonatal lung injury not only by preventing structural elastin degradation, but also by blocking elastin fragment-induced LM influx, thus preventing tissue injury from LM-derived peroxynitrite formation. Copyright © 2015 the American Physiological Society.

Insights into the role of elastin in vocal fold health and disease

PubMed Central

Moore, Jaime

2011-01-01

Elastic fibers are large, complex and surprisingly poorly understood extracellular matrix (ECM) macromolecules. The elastin fiber, generated from a single human gene - elastin (ELN), is a self assembling integral protein that endows critical mechanic proprieties to elastic tissues and organs such as the skin, lungs, and arteries. The biology of elastic fibers is complex because they have multiple components, a tightly regulated developmental deposition, a multi-step hierarchical assembly and unique biomechanical functions. Elastin is present in vocal folds, where it plays a pivotal role in the quality of phonation. This review article provides an overview of the genesis of elastin and its wide- ranging structure and function. Specific distribution within the vocal fold lamina propria across the lifespan in normal and pathological states and its contribution to vocal fold biomechanics will be examined. Elastin and elastin-derived molecules are increasingly investigated for their application in tissue engineering. The properties of various elastin– based materials will be discussed and their current and future applications evaluated. A new level of understanding of the biomechanical properties of vocal fold elastin composites and their molecular basis should lead to new strategies for elastic fiber repair and regeneration in aging and disease. PMID:21708449

Development of Tissue-Engineered Ligaments: Elastin Promotes Regeneration of the Rabbit Medial Collateral Ligament.

PubMed

Hirukawa, Masaki; Katayama, Shingo; Sato, Tatsuya; Yamada, Masayoshi; Kageyama, Satoshi; Unno, Hironori; Suzuki, Yoshiaki; Miura, Yoshihiro; Shiratsuchi, Eri; Hasegawa, Masahiro; Miyamoto, Keiichi; Horiuchi, Takashi

2017-12-21

When ligaments are injured, reconstructive surgery is sometimes required to restore function. Methods of reconstructive surgery include transplantation of an artificial ligament and autotransplantation of a tendon. However, these methods have limitations related to the strength of the bone-ligament insertion and biocompatibility of the transplanted tissue after surgery. Therefore, it is necessary to develop new reconstruction methods and pursue the development of artificial ligaments. Elastin is a major component of elastic fibers and ligaments. However, the role of elastin in ligament regeneration has not been described. Here, we developed a rabbit model of a medial collateral ligament (MCL) rupture and treated animal knees with exogenous elastin [100 µg/(0.5 mL·week)] for 6 or 12 weeks. Elastin treatment increased gene expression and protein content of collagen and elastin (gene expression, 6-fold and 42-fold, respectively; protein content, 1.6-fold and 1.9-fold, respectively), and also increased the elastic modulus of MCL increased with elastin treatment (2-fold) compared with the controls. Our data suggest that elastin is involved in the regeneration of damaged ligaments. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Methods in elastic tissue biology: elastin isolation and purification.

PubMed

Mecham, Robert P

2008-05-01

Elastin provides recoil to tissues subjected to repeated stretch, such as blood vessels and the lung. It is encoded by a single gene in mammals and is secreted as a 60-70 kDa monomer called tropoelastin. The functional form of the protein is that of a large, highly crosslinked polymer that organizes as sheets or fibers in the extracellular matrix. Purification of mature, crosslinked elastin is problematic because its insolubility precludes its isolation using standard wet-chemistry techniques. Instead, relatively harsh experimental approaches designed to remove non-elastin 'contaminates' are employed to generate an insoluble product that has the amino acid composition expected of elastin. Although soluble, tropoelastin also presents problems for isolation and purification. The protein's extreme stickiness and susceptibility to proteolysis requires careful attention during purification and in tropoelastin-based assays. This article describes the most common approaches for purification of insoluble elastin and tropoelastin. It also addresses key aspects of studying tropoelastin production in cultured cells, where elastin expression is highly dependent upon cell type, culture conditions, and passage number.

Cellulose microfibril crystallinity is reduced by mutating C-terminal transmembrane region residues CESA1A903V and CESA3T942I of cellulose synthase.

PubMed

Harris, Darby M; Corbin, Kendall; Wang, Tuo; Gutierrez, Ryan; Bertolo, Ana L; Petti, Carloalberto; Smilgies, Detlef-M; Estevez, José Manuel; Bonetta, Dario; Urbanowicz, Breeanna R; Ehrhardt, David W; Somerville, Chris R; Rose, Jocelyn K C; Hong, Mei; Debolt, Seth

2012-03-13

The mechanisms underlying the biosynthesis of cellulose in plants are complex and still poorly understood. A central question concerns the mechanism of microfibril structure and how this is linked to the catalytic polymerization action of cellulose synthase (CESA). Furthermore, it remains unclear whether modification of cellulose microfibril structure can be achieved genetically, which could be transformative in a bio-based economy. To explore these processes in planta, we developed a chemical genetic toolbox of pharmacological inhibitors and corresponding resistance-conferring point mutations in the C-terminal transmembrane domain region of CESA1(A903V) and CESA3(T942I) in Arabidopsis thaliana. Using (13)C solid-state nuclear magnetic resonance spectroscopy and X-ray diffraction, we show that the cellulose microfibrils displayed reduced width and an additional cellulose C4 peak indicative of a degree of crystallinity that is intermediate between the surface and interior glucans of wild type, suggesting a difference in glucan chain association during microfibril formation. Consistent with measurements of lower microfibril crystallinity, cellulose extracts from mutated CESA1(A903V) and CESA3(T942I) displayed greater saccharification efficiency than wild type. Using live-cell imaging to track fluorescently labeled CESA, we found that these mutants show increased CESA velocities in the plasma membrane, an indication of increased polymerization rate. Collectively, these data suggest that CESA1(A903V) and CESA3(T942I) have modified microfibril structure in terms of crystallinity and suggest that in plants, as in bacteria, crystallization biophysically limits polymerization.

Cellulose microfibril crystallinity is reduced by mutating C-terminal transmembrane region residues CESA1A903V and CESA3T942I of cellulose synthase

PubMed Central

Harris, Darby M.; Corbin, Kendall; Wang, Tuo; Gutierrez, Ryan; Bertolo, Ana L.; Petti, Carloalberto; Smilgies, Detlef-M.; Estevez, José Manuel; Bonetta, Dario; Urbanowicz, Breeanna R.; Ehrhardt, David W.; Somerville, Chris R.; Rose, Jocelyn K. C.; Hong, Mei; DeBolt, Seth

2012-01-01

The mechanisms underlying the biosynthesis of cellulose in plants are complex and still poorly understood. A central question concerns the mechanism of microfibril structure and how this is linked to the catalytic polymerization action of cellulose synthase (CESA). Furthermore, it remains unclear whether modification of cellulose microfibril structure can be achieved genetically, which could be transformative in a bio-based economy. To explore these processes in planta, we developed a chemical genetic toolbox of pharmacological inhibitors and corresponding resistance-conferring point mutations in the C-terminal transmembrane domain region of CESA1A903V and CESA3T942I in Arabidopsis thaliana. Using 13C solid-state nuclear magnetic resonance spectroscopy and X-ray diffraction, we show that the cellulose microfibrils displayed reduced width and an additional cellulose C4 peak indicative of a degree of crystallinity that is intermediate between the surface and interior glucans of wild type, suggesting a difference in glucan chain association during microfibril formation. Consistent with measurements of lower microfibril crystallinity, cellulose extracts from mutated CESA1A903V and CESA3T942I displayed greater saccharification efficiency than wild type. Using live-cell imaging to track fluorescently labeled CESA, we found that these mutants show increased CESA velocities in the plasma membrane, an indication of increased polymerization rate. Collectively, these data suggest that CESA1A903V and CESA3T942I have modified microfibril structure in terms of crystallinity and suggest that in plants, as in bacteria, crystallization biophysically limits polymerization. PMID:22375033

Cellulose microfibril structure: inspirations from plant diversity

NASA Astrophysics Data System (ADS)

Roberts, A. W.

2018-03-01

Cellulose microfibrils are synthesized at the plasma membrane by cellulose synthase catalytic subunits that associate to form cellulose synthesis complexes. Variation in the organization of these complexes underlies the variation in cellulose microfibril structure among diverse organisms. However, little is known about how the catalytic subunits interact to form complexes with different morphologies. We are using an evolutionary approach to investigate the roles of different catalytic subunit isoforms in organisms that have rosette-type cellulose synthesis complexes.

Cobtorin target analysis reveals that pectin functions in the deposition of cellulose microfibrils in parallel with cortical microtubules.

PubMed

Yoneda, Arata; Ito, Takuya; Higaki, Takumi; Kutsuna, Natsumaro; Saito, Tamio; Ishimizu, Takeshi; Osada, Hiroyuki; Hasezawa, Seiichiro; Matsui, Minami; Demura, Taku

2010-11-01

Cellulose and pectin are major components of primary cell walls in plants, and it is believed that their mechanical properties are important for cell morphogenesis. It has been hypothesized that cortical microtubules guide the movement of cellulose microfibril synthase in a direction parallel with the microtubules, but the mechanism by which this alignment occurs remains unclear. We have previously identified cobtorin as an inhibitor that perturbs the parallel relationship between cortical microtubules and nascent cellulose microfibrils. In this study, we searched for the protein target of cobtorin, and we found that overexpression of pectin methylesterase and polygalacturonase suppressed the cobtorin-induced cell-swelling phenotype. Furthermore, treatment with polygalacturonase restored the deposition of cellulose microfibrils in the direction parallel with cortical microtubules, and cobtorin perturbed the distribution of methylated pectin. These results suggest that control over the properties of pectin is important for the deposition of cellulose microfibrils and/or the maintenance of their orientation parallel with the cortical microtubules. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax.

PubMed

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-03-06

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy.

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax

PubMed Central

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-01-01

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy. PMID:19726440

Lysyl Oxidase Induces Vascular Oxidative Stress and Contributes to Arterial Stiffness and Abnormal Elastin Structure in Hypertension: Role of p38MAPK.

PubMed

Martínez-Revelles, Sonia; García-Redondo, Ana B; Avendaño, María S; Varona, Saray; Palao, Teresa; Orriols, Mar; Roque, Fernanda R; Fortuño, Ana; Touyz, Rhian M; Martínez-González, Jose; Salaices, Mercedes; Rodríguez, Cristina; Briones, Ana M

2017-09-01

Vascular stiffness, structural elastin abnormalities, and increased oxidative stress are hallmarks of hypertension. Lysyl oxidase (LOX) is an elastin crosslinking enzyme that produces H 2 O 2 as a by-product. We addressed the interplay between LOX, oxidative stress, vessel stiffness, and elastin. Angiotensin II (Ang II)-infused hypertensive mice and spontaneously hypertensive rats (SHR) showed increased vascular LOX expression and stiffness and an abnormal elastin structure. Mice over-expressing LOX in vascular smooth muscle cells (TgLOX) exhibited similar mechanical and elastin alterations to those of hypertensive models. LOX inhibition with β-aminopropionitrile (BAPN) attenuated mechanical and elastin alterations in TgLOX mice, Ang II-infused mice, and SHR. Arteries from TgLOX mice, Ang II-infused mice, and/or SHR exhibited increased vascular H 2 O 2 and O 2 .- levels, NADPH oxidase activity, and/or mitochondrial dysfunction. BAPN prevented the higher oxidative stress in hypertensive models. Treatment of TgLOX and Ang II-infused mice and SHR with the mitochondrial-targeted superoxide dismutase mimetic mito-TEMPO, the antioxidant apocynin, or the H 2 O 2 scavenger polyethylene glycol-conjugated catalase (PEG-catalase) reduced oxidative stress, vascular stiffness, and elastin alterations. Vascular p38 mitogen-activated protein kinase (p38MAPK) activation was increased in Ang II-infused and TgLOX mice and this effect was prevented by BAPN, mito-TEMPO, or PEG-catalase. SB203580, the p38MAPK inhibitor, normalized vessel stiffness and elastin structure in TgLOX mice. We identify LOX as a novel source of vascular reactive oxygen species and a new pathway involved in vascular stiffness and elastin remodeling in hypertension. LOX up-regulation is associated with enhanced oxidative stress that promotes p38MAPK activation, elastin structural alterations, and vascular stiffness. This pathway contributes to vascular abnormalities in hypertension. Antioxid. Redox Signal. 27, 379-397.

Lysyl Oxidase Induces Vascular Oxidative Stress and Contributes to Arterial Stiffness and Abnormal Elastin Structure in Hypertension: Role of p38MAPK

PubMed Central

Martínez-Revelles, Sonia; García-Redondo, Ana B.; Avendaño, María S.; Varona, Saray; Palao, Teresa; Orriols, Mar; Roque, Fernanda R.; Fortuño, Ana; Touyz, Rhian M.; Martínez-González, Jose; Salaices, Mercedes

2017-01-01

Abstract Aims: Vascular stiffness, structural elastin abnormalities, and increased oxidative stress are hallmarks of hypertension. Lysyl oxidase (LOX) is an elastin crosslinking enzyme that produces H2O2 as a by-product. We addressed the interplay between LOX, oxidative stress, vessel stiffness, and elastin. Results: Angiotensin II (Ang II)-infused hypertensive mice and spontaneously hypertensive rats (SHR) showed increased vascular LOX expression and stiffness and an abnormal elastin structure. Mice over-expressing LOX in vascular smooth muscle cells (TgLOX) exhibited similar mechanical and elastin alterations to those of hypertensive models. LOX inhibition with β-aminopropionitrile (BAPN) attenuated mechanical and elastin alterations in TgLOX mice, Ang II-infused mice, and SHR. Arteries from TgLOX mice, Ang II-infused mice, and/or SHR exhibited increased vascular H2O2 and O2.− levels, NADPH oxidase activity, and/or mitochondrial dysfunction. BAPN prevented the higher oxidative stress in hypertensive models. Treatment of TgLOX and Ang II-infused mice and SHR with the mitochondrial-targeted superoxide dismutase mimetic mito-TEMPO, the antioxidant apocynin, or the H2O2 scavenger polyethylene glycol-conjugated catalase (PEG-catalase) reduced oxidative stress, vascular stiffness, and elastin alterations. Vascular p38 mitogen-activated protein kinase (p38MAPK) activation was increased in Ang II-infused and TgLOX mice and this effect was prevented by BAPN, mito-TEMPO, or PEG-catalase. SB203580, the p38MAPK inhibitor, normalized vessel stiffness and elastin structure in TgLOX mice. Innovation: We identify LOX as a novel source of vascular reactive oxygen species and a new pathway involved in vascular stiffness and elastin remodeling in hypertension. Conclusion: LOX up-regulation is associated with enhanced oxidative stress that promotes p38MAPK activation, elastin structural alterations, and vascular stiffness. This pathway contributes to vascular abnormalities in hypertension. Antioxid. Redox Signal. 27, 379–397. PMID:28010122

Collagen and elastin cross-linking is altered during aberrant late lung development associated with hyperoxia.

PubMed

Mižíková, Ivana; Ruiz-Camp, Jordi; Steenbock, Heiko; Madurga, Alicia; Vadász, István; Herold, Susanne; Mayer, Konstantin; Seeger, Werner; Brinckmann, Jürgen; Morty, Rory E

2015-06-01

Maturation of the lung extracellular matrix (ECM) plays an important role in the formation of alveolar gas exchange units. A key step in ECM maturation is cross-linking of collagen and elastin, which imparts stability and functionality to the ECM. During aberrant late lung development in bronchopulmonary dysplasia (BPD) patients and animal models of BPD, alveolarization is blocked, and the function of ECM cross-linking enzymes is deregulated, suggesting that perturbed ECM cross-linking may impact alveolarization. In a hyperoxia (85% O2)-based mouse model of BPD, blunted alveolarization was accompanied by alterations to lung collagen and elastin levels and cross-linking. Total collagen levels were increased (by 63%). The abundance of dihydroxylysinonorleucine collagen cross-links and the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio were increased by 11 and 18%, respectively, suggestive of a profibrotic state. In contrast, insoluble elastin levels and the abundance of the elastin cross-links desmosine and isodesmosine in insoluble elastin were decreased by 35, 30, and 21%, respectively. The lung collagen-to-elastin ratio was threefold increased. Treatment of hyperoxia-exposed newborn mice with the lysyl oxidase inhibitor β-aminopropionitrile partially restored normal collagen levels, normalized the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio, partially normalized desmosine and isodesmosine cross-links in insoluble elastin, and partially restored elastin foci structure in the developing septa. However, β-aminopropionitrile administration concomitant with hyperoxia exposure did not improve alveolarization, evident from unchanged alveolar surface area and alveoli number, and worsened septal thickening (increased by 12%). These data demonstrate that collagen and elastin cross-linking are perturbed during the arrested alveolarization of developing mouse lungs exposed to hyperoxia. Copyright © 2015 the American Physiological Society.

In vitro cross-linking of elastin peptides and molecular characterization of the resultant biomaterials.

PubMed

Heinz, Andrea; Ruttkies, Christoph K H; Jahreis, Günther; Schräder, Christoph U; Wichapong, Kanin; Sippl, Wolfgang; Keeley, Fred W; Neubert, Reinhard H H; Schmelzer, Christian E H

2013-04-01

Elastin is a vital protein and the major component of elastic fibers which provides resilience to many vertebrate tissues. Elastin's structure and function are influenced by extensive cross-linking, however, the cross-linking pattern is still unknown. Small peptides containing reactive allysine residues based on sequences of cross-linking domains of human elastin were incubated in vitro to form cross-links characteristic of mature elastin. The resultant insoluble polymeric biomaterials were studied by scanning electron microscopy. Both, the supernatants of the samples and the insoluble polymers, after digestion with pancreatic elastase or trypsin, were furthermore comprehensively characterized on the molecular level using MALDI-TOF/TOF mass spectrometry. MS(2) data was used to develop the software PolyLinX, which is able to sequence not only linear and bifunctionally cross-linked peptides, but for the first time also tri- and tetrafunctionally cross-linked species. Thus, it was possible to identify intra- and intermolecular cross-links including allysine aldols, dehydrolysinonorleucines and dehydromerodesmosines. The formation of the tetrafunctional cross-link desmosine or isodesmosine was unexpected, however, could be confirmed by tandem mass spectrometry and molecular dynamics simulations. The study demonstrated that it is possible to produce biopolymers containing polyfunctional cross-links characteristic of mature elastin from small elastin peptides. MALDI-TOF/TOF mass spectrometry and the newly developed software PolyLinX proved suitable for sequencing of native cross-links in proteolytic digests of elastin-like biomaterials. The study provides important insight into the formation of native elastin cross-links and represents a considerable step towards the characterization of the complex cross-linking pattern of mature elastin. Copyright © 2013 Elsevier B.V. All rights reserved.

Systemic elastin degradation in chronic obstructive pulmonary disease.

PubMed

Maclay, John D; McAllister, David A; Rabinovich, Roberto; Haq, Imran; Maxwell, Scott; Hartland, Stephen; Connell, Martin; Murchison, John T; van Beek, Edwin J R; Gray, Robert D; Mills, Nicholas L; Macnee, William

2012-07-01

Development of emphysema and vascular stiffness in chronic obstructive pulmonary disease (COPD) may be due to a common mechanism of susceptibility to pulmonary and systemic elastin degradation. To investigate whether patients with COPD have evidence of systemic elastin degradation in the skin. The authors measured cutaneous elastin degradation using immunohistochemistry (percentage area of elastin fibres) in sun-exposed (exposed) and non-sun-exposed (non-exposed) skin biopsies in 16 men with COPD and 15 controls matched for age and cigarette smoke exposure. Quantitative PCR of matrix metalloproteinase (MMP)-2, -9, -12 and tissue inhibitor of metalloproteinase-1 mRNA and zymography for protein expression of MMP-2 and -9 were performed on homogenised skin. Arterial stiffness and emphysema severity were measured using carotid-femoral pulse wave velocity and quantitative CT scanning. Skin elastin degradation was greater in exposed and non-exposed skin of patients with COPD compared with controls (exposed, mean (SD); 43.5 (12.1)% vs 26.3 (6.9)%, p<0.001; non-exposed 22.4 (5.2)% vs 18.1 (4.3)%, p=0.02). Cutaneous expression of MMP-9 mRNA and proMMP-9 concentrations was increased in exposed skin of COPD patients (p=0.004 and p=0.02, respectively) and was also associated with increased skin elastin degradation (r=0.62, p<0.001 and r=0.47, p=0.01, respectively). In the entire cohort of ex-smokers, cutaneous elastin degradation was associated with emphysema severity, FEV(1) and pulse wave velocity. Patients with COPD have increased skin elastin degradation compared with controls, which is related to emphysema severity and arterial stiffness. Systemic elastin degradation due to increased proteolytic activity may represent a novel shared mechanism for the pulmonary, vascular and cutaneous features of COPD.

Dimerization effects on coacervation property of an elastin-derived synthetic peptide (FPGVG)5.

PubMed

Suyama, Keitaro; Taniguchi, Suguru; Tatsubo, Daiki; Maeda, Iori; Nose, Takeru

2016-04-01

Elastin, a core protein of the elastic fibers, exhibits the coacervation (temperature-dependent reversible association/dissociation) under physiological conditions. Because of this characteristic, elastin and elastin-derived peptides have been considered to be useful as base materials for developing various biomedical products, skin substitutes, synthetic vascular grafts, and drug delivery systems. Although elastin-derived polypeptide (Val-Pro-Gly-Val-Gly)n also has been known to demonstrate coacervation property, a sufficiently high (VPGVG)n repetition number (n>40) is required for coacervation. In the present study, a series of elastin-derived peptide (Phe-Pro-Gly-Val-Gly)5 dimers possessing high coacervation potential were newly developed. These novel dimeric peptides exhibited coacervation at significantly lower concentrations and temperatures than the commonly used elastin-derived peptide analogs; this result suggests that the coacervation ability of the peptides is enhanced by dimerization. Circular dichroism (CD) measurements indicate that the dimers undergo similar temperature-dependent and reversible conformational changes when coacervation occurs. The molecular dynamics calculation results reveal that the sheet-turn-sheet motif involving a type II β-turn-like structure commonly observed among the dimers and caused formation of globular conformation of them. These synthesized peptide dimers may be useful not only as model peptides for structural analysis of elastin and elastin-derived peptides, but also as base materials for developing various temperature-sensitive biomedical and industrial products. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

A wrinkle in flight: the role of elastin fibres in the mechanical behaviour of bat wing membranes

PubMed Central

Cheney, Jorn A.; Konow, Nicolai; Bearnot, Andrew; Swartz, Sharon M.

2015-01-01

Bats fly using a thin wing membrane composed of compliant, anisotropic skin. Wing membrane skin deforms dramatically as bats fly, and its three-dimensional configurations depend, in large part, on the mechanical behaviour of the tissue. Large, macroscopic elastin fibres are an unusual mechanical element found in the skin of bat wings. We characterize the fibre orientation and demonstrate that elastin fibres are responsible for the distinctive wrinkles in the surrounding membrane matrix. Uniaxial mechanical testing of the wing membrane, both parallel and perpendicular to elastin fibres, is used to distinguish the contribution of elastin and the surrounding matrix to the overall membrane mechanical behaviour. We find that the matrix is isotropic within the plane of the membrane and responsible for bearing load at high stress; elastin fibres are responsible for membrane anisotropy and only contribute substantially to load bearing at very low stress. The architecture of elastin fibres provides the extreme extensibility and self-folding/self-packing of the wing membrane skin. We relate these findings to flight with membrane wings and discuss the aeromechanical significance of elastin fibre pre-stress, membrane excess length, and how these parameters may aid bats in resisting gusts and preventing membrane flutter. PMID:25833238

A wrinkle in flight: the role of elastin fibres in the mechanical behaviour of bat wing membranes.

PubMed

Cheney, Jorn A; Konow, Nicolai; Bearnot, Andrew; Swartz, Sharon M

2015-05-06

Bats fly using a thin wing membrane composed of compliant, anisotropic skin. Wing membrane skin deforms dramatically as bats fly, and its three-dimensional configurations depend, in large part, on the mechanical behaviour of the tissue. Large, macroscopic elastin fibres are an unusual mechanical element found in the skin of bat wings. We characterize the fibre orientation and demonstrate that elastin fibres are responsible for the distinctive wrinkles in the surrounding membrane matrix. Uniaxial mechanical testing of the wing membrane, both parallel and perpendicular to elastin fibres, is used to distinguish the contribution of elastin and the surrounding matrix to the overall membrane mechanical behaviour. We find that the matrix is isotropic within the plane of the membrane and responsible for bearing load at high stress; elastin fibres are responsible for membrane anisotropy and only contribute substantially to load bearing at very low stress. The architecture of elastin fibres provides the extreme extensibility and self-folding/self-packing of the wing membrane skin. We relate these findings to flight with membrane wings and discuss the aeromechanical significance of elastin fibre pre-stress, membrane excess length, and how these parameters may aid bats in resisting gusts and preventing membrane flutter. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Methods in Elastic Tissue Biology: Elastin Isolation and Purification

PubMed Central

Mecham, Robert P.

2008-01-01

Elastin provides recoil to tissues subjected to repeated stretch, such as blood vessels and the lung. It is encoded by a single gene in mammals and is secreted as a 60–70 kDa monomer call tropoelastin. The functional form of the protein is that of a large, highly crosslinked polymer that organizes as sheets or fibers in the extracellular matrix. Purification of mature, crosslinked elastin is problematic because its insolubility precludes its isolation using standard wet-chemistry techniques. Instead, relatively harsh experimental approaches designed to remove non-elastin ‘contaminates’ are employed to generate an insoluble product that has the amino acid composition expected of elastin. Although soluble, tropoelastin also presents problems for isolation and purification. The protein’s extreme stickiness and susceptibility to proteolysis requires careful attention during purification and in tropoelastin-based assays. This article describes the most common approaches for purification of insoluble elastin and tropoelastin. It also addresses key aspects of studying tropoelastin production in cultured cells, where elastin expression is highly dependent upon cell type, culture conditions, and passage number. PMID:18442703

Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering.

PubMed

Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

2013-07-01

In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of Enzymatic Degradation of Cellulose Microfibrils using Quantitative Surface Plasmon Resonance Imaging

NASA Astrophysics Data System (ADS)

Reiter, Kyle; Raegen, Adam; Allen, Scott; Quirk, Amanda; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2013-03-01

Cellulose is the largest component of biomass on Earth and, as a result, is a significant potential energy source. The production of cellulosic ethanol as a fuel source requires conversion of cellulose fibers into fermentable sugars. Increasing our understanding of the action of cellulose enzymes (cellulases) on cellulose microfibrils is an important step in developing more efficient industrial processes for the production of cellulosic ethanol. We have used a custom designed Surface Plasmon Resonance imaging (SPRi) device to study the action of cellulases from the Hypocrea jecorinasecretome on bacterial cellulose microfibrils. This has allowed us to determine the rates of action and extent of degradation of cellulose microfibrils on exposure to both individual cellulases and combinations of different classes of cellulases, which has allowed us to investigate synergistic interactions between the cellulases.

Enhanced cellulose orientation analysis in complex model plant tissues.

PubMed

Rüggeberg, Markus; Saxe, Friederike; Metzger, Till H; Sundberg, Björn; Fratzl, Peter; Burgert, Ingo

2013-09-01

The orientation distribution of cellulose microfibrils in the plant cell wall is a key parameter for understanding anisotropic plant growth and mechanical behavior. However, precisely visualizing cellulose orientation in the plant cell wall has ever been a challenge due to the small size of the cellulose microfibrils and the complex network of polymers in the plant cell wall. X-ray diffraction is one of the most frequently used methods for analyzing cellulose orientation in single cells and plant tissues, but the interpretation of the diffraction images is complex. Traditionally, circular or square cells and Gaussian orientation of the cellulose microfibrils have been assumed to elucidate cellulose orientation from the diffraction images. However, the complex tissue structures of common model plant systems such as Arabidopsis or aspen (Populus) require a more sophisticated approach. We present an evaluation procedure which takes into account the precise cell geometry and is able to deal with complex microfibril orientation distributions. The evaluation procedure reveals the entire orientation distribution of the cellulose microfibrils, reflecting different orientations within the multi-layered cell wall. By analyzing aspen wood and Arabidopsis stems we demonstrate the versatility of this method and show that simplifying assumptions on geometry and orientation distributions can lead to errors in the calculated microfibril orientation pattern. The simulation routine is intended to be used as a valuable tool for nanostructural analysis of plant cell walls and is freely available from the authors on request. Copyright © 2013 Elsevier Inc. All rights reserved.

Multiphoton microscopy observations of 3D elastin and collagen fiber microstructure changes during pressurization in aortic media.

PubMed

Sugita, Shukei; Matsumoto, Takeo

2017-06-01

Elastin and collagen fibers play important roles in the mechanical properties of aortic media. Because knowledge of local fiber structures is required for detailed analysis of blood vessel wall mechanics, we investigated 3D microstructures of elastin and collagen fibers in thoracic aortas and monitored changes during pressurization. Using multiphoton microscopy, autofluorescence images from elastin and second harmonic generation signals from collagen were acquired in media from rabbit thoracic aortas that were stretched biaxially to restore physiological dimensions. Both elastin and collagen fibers were observed in all longitudinal-circumferential plane images, whereas alternate bright and dark layers were observed along the radial direction and were recognized as elastic laminas (ELs) and smooth muscle-rich layers (SMLs), respectively. Elastin and collagen fibers are mainly oriented in the circumferential direction, and waviness of collagen fibers was significantly higher than that of elastin fibers. Collagen fibers were more undulated in longitudinal than in radial direction, whereas undulation of elastin fibers was equibiaxial. Changes in waviness of collagen fibers during pressurization were then evaluated using 2-dimensional fast Fourier transform in mouse aortas, and indices of waviness of collagen fibers decreased with increases in intraluminal pressure. These indices also showed that collagen fibers in SMLs became straight at lower intraluminal pressures than those in EL, indicating that SMLs stretched more than ELs. These results indicate that deformation of the aorta due to pressurization is complicated because of the heterogeneity of tissue layers and differences in elastic properties of ELs, SMLs, and surrounding collagen and elastin.

Retained structural integrity of collagen and elastin within cryopreserved human heart valve tissue as detected by two-photon laser scanning confocal microscopy.

PubMed

Gerson, Cindy J; Goldstein, Steven; Heacox, Albert E

2009-10-01

Cryopreservation is commonly used for the long-term storage of heart valve allografts. Despite the excellent hemodynamic performance and durability of cryopreserved allografts, reports have questioned whether cryopreservation affects the valvular structural proteins, collagen and elastin. This study uses two-photon laser scanning confocal microscopy (LSCM) to evaluate the effect of cryopreservation on collagen and elastin integrity within the leaflet and conduit of aortic and pulmonary human heart valves. To permit pairwise comparisons of fresh and cryopreserved tissue, test valves were bisected longitudinally with one segment imaged fresh and the other imaged after cryopreservation and brief storage in liquid nitrogen. Collagen was detected by second harmonic generation (SHG) stimulation and elastin by autofluorescence excitation. Qualitative analysis of all resultant images indicated the maintenance of collagen and elastin structure within leaflet and conduit post-cryopreservation. Analysis of the optimized percent laser transmission (OPLT) required for full dynamic range imaging of collagen and elastin showed that OPLT observations were highly variable among both fresh and cryopreserved samples. Changes in donor-specific average OPLT in response to cryopreservation exhibited no consistent directional trend. The donor-aggregated results predominantly showed no statistically significant change in collagen and elastin average OPLT due to cryopreservation. Since OPLT has an inverse relationship with structural signal intensity, these results indicate that there was largely no statistical difference in collagen and elastin signal strength between fresh and cryopreserved tissue. Overall, this study indicates that the conventional cryopreservation of human heart valve allografts does not detrimentally affect their collagen and elastin structural integrity.

Chromosomal mapping of quantitative trait loci controlling elastin content in rat aorta.

PubMed

Gauguier, Dominique; Behmoaras, Jacques; Argoud, Karène; Wilder, Steven P; Pradines, Christelle; Bihoreau, Marie Thérèse; Osborne-Pellegrin, Mary; Jacob, Marie Paule

2005-03-01

Extracellular matrix molecules such as elastin and collagens provide mechanical support to the vessel wall. In addition to its structural role, elastin is a regulator that maintains homeostasis through biologic signaling. Genetically determined minor modifications in elastin and collagen in the aorta could influence the onset and evolution of arterial pathology, such as hypertension and its complications. We previously demonstrated that the inbred Brown Norway (BN) rat shows an aortic elastin deficit in both abdominal and thoracic segments, partly because of a decrease in tropoelastin synthesis when compared with the LOU rat, that elastin gene polymorphisms in these strains do not significantly account for. After a genome-wide search for quantitative trait loci (QTL) influencing the aortic elastin, collagen, and cell protein contents in an F2 population derived from BN and LOU rats, we identified on chromosomes 2 and 14, 3 QTL specifically controlling elastin levels, and a further highly significant QTL on chromosome 17 linked to the level of cell proteins. We also mapped 3 highly significant QTL linked to body weight (on chromosomes 1 and 3) and heart weight (on chromosome 1) in the cross. This study demonstrates the polygenic control of the content of key components of the arterial wall. Such information represents a first step in understanding possible mechanisms involved in dysregulation of these parameters in arterial pathology.

Biophysical characterization of a de novo elastin

NASA Astrophysics Data System (ADS)

Greenland, Kelly Nicole

Natural human elastin is found in tissue such as the lungs, arteries, and skin. This protein is formed at birth with no mechanism present to repair or supplement the initial quantity formed. As a result, the functionality and durability of elastin's elasticity is critically important. To date, the mechanics of this ability to stretch and recoil is not fully understood. This study utilizes de novo protein design to create a small library of simplistic versions of elastin-like proteins, demonstrate the elastin-like proteins, maintain elastin's functionality, and inquire into its structure using solution nuclear magnetic resonance (NMR). Elastin is formed from cross-linked tropoelastin. Therefore, the first generation of designed proteins consisted of one protein that utilized homogony of interspecies tropoelastin by using three common domains, two hydrophobic and one cross-linking domains. Basic modifications were made to open the hydrophobic region and also to make the protein easier to purify and characterize. The designed protein maintained its functionality, self-aggregating as the temperature increased. Uniquely, the protein remained self-aggregated as the temperature returned below the critical transition temperature. Self-aggregation was additionally induced by increasing salt concentrations and by modifying the pH. The protein appeared to have little secondary structure when studied with solution NMR. These results fueled a second generation of designed elastin-like proteins. This generation contained variations designed to study the cross-linking domain, one specific hydrophobic domain, and the effect of the length of the elastin-like protein. The cross-linking domain in one variation has been significantly modified while the flanking hydrophobic domains have remained unchanged. This characterization of this protein will answer questions regarding the specificity of the homologous nature of the cross-linking domain of tropoelastin across species. A second protein has additional hydrophobic domains flanking the originally designed elastin-like protein. The characterization of this protein will answer questions regarding the functionality of longer or more hydrophobic elastin-like proteins. The final variation designed is one hydrophobic domain and the new cross-linking domain repeating several times. The characterization of this protein will answer questions regarding the specific hydrophobic domain and its functionality.

Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

PubMed

Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

2003-08-15

Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

Use of elastin fibre detection in the diagnosis of ventilator associated pneumonia.

PubMed

el-Ebiary, M; Torres, A; González, J; Martos, A; Puig de la Bellacasa, J; Ferrer, M; Rodriguez-Roisin, R

1995-01-01

Elastin fibre detection could be a simple and reliable marker of ventilator associated pneumonia. To confirm this, a prospective study was undertaken to evaluate the diagnostic yield of elastin fibre detection in the diagnosis of ventilator associated pneumonia. Seventy eight mechanically ventilated patients were evaluated by examining endotracheal aspirates for the presence of elastin fibres. All patients were previously treated with antibiotics. Quantitative bacterial cultures of endotracheal aspirates and protected specimen brush samples were also performed. Patients were classified into three diagnostic categories: group 1, definite pneumonia (n = 25); group 2, probable pneumonia (n = 35); and group 3, controls (n = 18). Patients with definite and probable pneumonia were grouped together. The presence of elastin fibres in endotracheal aspirate samples was more frequent in groups 1 and 2, being found in 19 of the 60 patients compared with five of the control group. Although the presence of elastin fibres had a low sensitivity (32%), it was a reasonably specific marker (72%) of pneumonia. This specificity increased to 86% and 81% respectively when only Gram negative bacilli and Pseudomonas aeruginosa pneumonia were considered. Again, calculated sensitivity was 43% and 44% when analysing cases infected by Gram negative bacilli and Ps aeruginosa, respectively. The negative predictive value of the detection of elastin fibres in pneumonia caused by Ps aeruginosa was 81%. Detection was more frequent with infection by Gram negative bacilli (14/19), particularly with Ps aeruginosa (8/14). By contrast, pneumonia due to Gram positive cocci or non-bacterial agents uncommonly resulted in positive elastin fibre preparations (4/19, 21%). When analysing patients with and without chronic obstructive pulmonary disease, the diagnostic value of elastin fibre detection did not change. Potassium hydroxide preparation of elastin fibres is a rapid and simple specific marker of ventilator associated pneumonia and may be a useful technique to help diagnose pulmonary infections in mechanically ventilated patients, although this assessment is at present limited to patients without adult respiratory distress syndrome.

Use of elastin fibre detection in the diagnosis of ventilator associated pneumonia.

PubMed Central

el-Ebiary, M.; Torres, A.; González, J.; Martos, A.; Puig de la Bellacasa, J.; Ferrer, M.; Rodriguez-Roisin, R.

1995-01-01

BACKGROUND--Elastin fibre detection could be a simple and reliable marker of ventilator associated pneumonia. To confirm this, a prospective study was undertaken to evaluate the diagnostic yield of elastin fibre detection in the diagnosis of ventilator associated pneumonia. METHODS--Seventy eight mechanically ventilated patients were evaluated by examining endotracheal aspirates for the presence of elastin fibres. All patients were previously treated with antibiotics. Quantitative bacterial cultures of endotracheal aspirates and protected specimen brush samples were also performed. Patients were classified into three diagnostic categories: group 1, definite pneumonia (n = 25); group 2, probable pneumonia (n = 35); and group 3, controls (n = 18). RESULTS--Patients with definite and probable pneumonia were grouped together. The presence of elastin fibres in endotracheal aspirate samples was more frequent in groups 1 and 2, being found in 19 of the 60 patients compared with five of the control group. Although the presence of elastin fibres had a low sensitivity (32%), it was a reasonably specific marker (72%) of pneumonia. This specificity increased to 86% and 81% respectively when only Gram negative bacilli and Pseudomonas aeruginosa pneumonia were considered. Again, calculated sensitivity was 43% and 44% when analysing cases infected by Gram negative bacilli and Ps aeruginosa, respectively. The negative predictive value of the detection of elastin fibres in pneumonia caused by Ps aeruginosa was 81%. Detection was more frequent with infection by Gram negative bacilli (14/19), particularly with Ps aeruginosa (8/14). By contrast, pneumonia due to Gram positive cocci or non-bacterial agents uncommonly resulted in positive elastin fibre preparations (4/19, 21%). When analysing patients with and without chronic obstructive pulmonary disease, the diagnostic value of elastin fibre detection did not change. CONCLUSIONS--Potassium hydroxide preparation of elastin fibres is a rapid and simple specific marker of ventilator associated pneumonia and may be a useful technique to help diagnose pulmonary infections in mechanically ventilated patients, although this assessment is at present limited to patients without adult respiratory distress syndrome. PMID:7886642

Degradation of tropoelastin and skin elastin by neprilysin.

PubMed

Mora Huertas, Angela C; Schmelzer, Christian E H; Luise, Chiara; Sippl, Wolfgang; Pietzsch, Markus; Hoehenwarter, Wolfgang; Heinz, Andrea

2018-03-01

Neprilysin is also known as skin fibroblast-derived elastase, and its up-regulation during aging is associated with impairments of the elastic fiber network, loss of skin elasticity and wrinkle formation. However, information on its elastase activity is still limited. The aim of this study was to investigate the degradation of fibrillar skin elastin by neprilysin and the influence of the donor's age on the degradation process using mass spectrometry and bioinformatics approaches. The results showed that cleavage by neprilysin is dependent on previous damage of elastin. While neprilysin does not cleave young and intact skin elastin well, it degrades elastin fibers from older donors, which may further promote aging processes. With regards to the cleavage behavior of neprilysin, a strong preference for Gly at P1 was found, while Gly, Ala and Val were well accepted at P1' upon cleavage of tropoelastin and skin elastin. The results of the study indicate that the progressive release of bioactive elastin peptides by neprilysin upon skin aging may enhance local tissue damage and accelerate extracellular matrix aging processes. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Extraction and characterization of elastin from poultry skin

NASA Astrophysics Data System (ADS)

Nadalian, Mehdi; Yusop, Salma Mohamad; Mustapha, Wan Aida Wan; Azman, Mohd Azri; Babji, Abdul Salam

2013-11-01

Poultry by-products have a great economic potential that need to be exploited. Poultry skin could be utilized to produce elastin, which is often incorporated in the production of functional food or medicine due to its antioxidative properties. This study was conducted to determine the physicochemical and microstructural characteristics of elastins isolated from broiler and spent hen skin. Analyses including proximate and amino acid composition along with transmission electron microscopy (TEM) were carried out. In this study, elastin was successfully extracted from broiler and spent hen skin using three successive solvents extract of NaCl, acetone and NaOH respectively. It was apparent that the fat content of extracted elastin from broiler skin was higher (P < 0.05) than spent hen's, with both samples recording less than 1% fat. Moreover, broiler skin elastin also had a higher protein content (68.3%) than spent hen's (67.8%). Both skin sources contained glycine as the major amino acid (19-20%), followed by glutamic acid, proline, alanine and arginine. The results of TEM indicated that the use of collagenase enzyme or further purification efforts should be incorporated along with the extraction methods used because of the presence of collagen and other debris in the resultant elastin.

Organization of pectic arabinan and galactan side chains in association with cellulose microfibrils in primary cell walls and related models envisaged.

PubMed

Zykwinska, Agata; Thibault, Jean-François; Ralet, Marie-Christine

2007-01-01

The structure of arabinan and galactan domains in association with cellulose microfibrils was investigated using enzymatic and alkali degradation procedures. Sugar beet and potato cell wall residues (called 'natural' composites), rich in pectic neutral sugar side chains and cellulose, as well as 'artificial' composites, created by in vitro adsorption of arabinan and galactan side chains onto primary cell wall cellulose, were studied. These composites were sequentially treated with enzymes specific for pectic side chains and hot alkali. The degradation approach used showed that most of the arabinan and galactan side chains are in strong interaction with cellulose and are not hydrolysed by pectic side chain-degrading enzymes. It seems unlikely that isolated arabinan and galactan chains are able to tether adjacent microfibrils. However, cellulose microfibrils may be tethered by different pectic side chains belonging to the same pectic macromolecule.

Hydrogen bonds and twist in cellulose microfibrils.

PubMed

Kannam, Sridhar Kumar; Oehme, Daniel P; Doblin, Monika S; Gidley, Michael J; Bacic, Antony; Downton, Matthew T

2017-11-01

There is increasing experimental and computational evidence that cellulose microfibrils can exist in a stable twisted form. In this study, atomistic molecular dynamics (MD) simulations are performed to investigate the importance of intrachain hydrogen bonds on the twist in cellulose microfibrils. We systematically enforce or block the formation of these intrachain hydrogen bonds by either constraining dihedral angles or manipulating charges. For the majority of simulations a consistent right handed twist is observed. The exceptions are two sets of simulations that block the O2-O6' intrachain hydrogen bond, where no consistent twist is observed in multiple independent simulations suggesting that the O2-O6' hydrogen bond can drive twist. However, in a further simulation where exocyclic group rotation is also blocked, right-handed twist still develops suggesting that intrachain hydrogen bonds are not necessary to drive twist in cellulose microfibrils. Copyright © 2017 Elsevier Ltd. All rights reserved.

3D electron tomography of pretreated biomass informs atomic modeling of cellulose microfibrils.

PubMed

Ciesielski, Peter N; Matthews, James F; Tucker, Melvin P; Beckham, Gregg T; Crowley, Michael F; Himmel, Michael E; Donohoe, Bryon S

2013-09-24

Fundamental insights into the macromolecular architecture of plant cell walls will elucidate new structure-property relationships and facilitate optimization of catalytic processes that produce fuels and chemicals from biomass. Here we introduce computational methodology to extract nanoscale geometry of cellulose microfibrils within thermochemically treated biomass directly from electron tomographic data sets. We quantitatively compare the cell wall nanostructure in corn stover following two leading pretreatment strategies: dilute acid with iron sulfate co-catalyst and ammonia fiber expansion (AFEX). Computational analysis of the tomographic data is used to extract mathematical descriptions for longitudinal axes of cellulose microfibrils from which we calculate their nanoscale curvature. These nanostructural measurements are used to inform the construction of atomistic models that exhibit features of cellulose within real, process-relevant biomass. By computational evaluation of these atomic models, we propose relationships between the crystal structure of cellulose Iβ and the nanoscale geometry of cellulose microfibrils.

Remote Exosites of the Catalytic Domain of Matrix Metalloproteinase-12 Enhance Elastin Degradation┼

PubMed Central

Fulcher, Yan G.; Van Doren, Steven R.

2011-01-01

How does matrix metalloproteinase-12 (MMP-12 or metalloelastase) degrade elastin with high specific activity? NMR suggested soluble elastin to cover surfaces of MMP-12 far from its active site. Two of these surfaces have been found, by mutagenesis guided by the BINDSIght approach, to affect degradation and affinity for elastin substrates but not a small peptide substrate. Main exosite 1 has been extended out to Asp124 that binds calcium. Novel exosite 2 comprises residues from the II–III loop and β-strand I near the back of the catalytic domain. The high exposure of these distal exosites may make them accessible to elastin made more flexible by partial hydrolysis. Importantly, combination of a lesion at each of exosites 1 and 2 and active site decreased catalytic competence towards soluble elastin by 13- to 18-fold to the level of MMP-3, homologue and poor elastase. Double mutant cycle analysis of conservative mutations of Met156 (exosite 2) and either Asp124 (exosite 1) or Ile180 (active site) had additive effects. Compared to polar substitutions observed in other MMPs, Met156 enhanced affinity and Ile180 kcat for soluble elastin. Both residues detracted from the higher folding stability with polar mutations. This resembles the trend in enzymes of an inverse relationship between folding stability and activity. Restoring Asp124 from combination mutants enhanced kcat for soluble elastin. In elastin degradation, exosites 1 and 2 contributed independently of each other and Ile180 at the active site, but with partial coupling to Ala182 near the active site. The concept of weak, separated interactions coalescing somewhat independently can be extended to this proteolytic digestion of a protein from fibrils. PMID:21967233

Aspen Tension Wood Fibers Contain β-(1→4)-Galactans and Acidic Arabinogalactans Retained by Cellulose Microfibrils in Gelatinous Walls1[OPEN

PubMed Central

Gorshkova, Tatyana; Mokshina, Natalia; Chernova, Tatyana; Ibragimova, Nadezhda; Salnikov, Vadim; Mikshina, Polina; Tryfona, Theodora; Banasiak, Alicja; Immerzeel, Peter; Dupree, Paul; Mellerowicz, Ewa J.

2015-01-01

Contractile cell walls are found in various plant organs and tissues such as tendrils, contractile roots, and tension wood. The tension-generating mechanism is not known but is thought to involve special cell wall architecture. We previously postulated that tension could result from the entrapment of certain matrix polymers within cellulose microfibrils. As reported here, this hypothesis was corroborated by sequential extraction and analysis of cell wall polymers that are retained by cellulose microfibrils in tension wood and normal wood of hybrid aspen (Populus tremula × Populus tremuloides). β-(1→4)-Galactan and type II arabinogalactan were the main large matrix polymers retained by cellulose microfibrils that were specifically found in tension wood. Xyloglucan was detected mostly in oligomeric form in the alkali-labile fraction and was enriched in tension wood. β-(1→4)-Galactan and rhamnogalacturonan I backbone epitopes were localized in the gelatinous cell wall layer. Type II arabinogalactans retained by cellulose microfibrils had a higher content of (methyl)glucuronic acid and galactose in tension wood than in normal wood. Thus, β-(1→4)-galactan and a specialized form of type II arabinogalactan are trapped by cellulose microfibrils specifically in tension wood and, thus, are the main candidate polymers for the generation of tensional stresses by the entrapment mechanism. We also found high β-galactosidase activity accompanying tension wood differentiation and propose a testable hypothesis that such activity might regulate galactan entrapment and, thus, mechanical properties of cell walls in tension wood. PMID:26378099

Aspen Tension Wood Fibers Contain β-(1---> 4)-Galactans and Acidic Arabinogalactans Retained by Cellulose Microfibrils in Gelatinous Walls.

PubMed

Gorshkova, Tatyana; Mokshina, Natalia; Chernova, Tatyana; Ibragimova, Nadezhda; Salnikov, Vadim; Mikshina, Polina; Tryfona, Theodora; Banasiak, Alicja; Immerzeel, Peter; Dupree, Paul; Mellerowicz, Ewa J

2015-11-01

Contractile cell walls are found in various plant organs and tissues such as tendrils, contractile roots, and tension wood. The tension-generating mechanism is not known but is thought to involve special cell wall architecture. We previously postulated that tension could result from the entrapment of certain matrix polymers within cellulose microfibrils. As reported here, this hypothesis was corroborated by sequential extraction and analysis of cell wall polymers that are retained by cellulose microfibrils in tension wood and normal wood of hybrid aspen (Populus tremula × Populus tremuloides). β-(1→4)-Galactan and type II arabinogalactan were the main large matrix polymers retained by cellulose microfibrils that were specifically found in tension wood. Xyloglucan was detected mostly in oligomeric form in the alkali-labile fraction and was enriched in tension wood. β-(1→4)-Galactan and rhamnogalacturonan I backbone epitopes were localized in the gelatinous cell wall layer. Type II arabinogalactans retained by cellulose microfibrils had a higher content of (methyl)glucuronic acid and galactose in tension wood than in normal wood. Thus, β-(1→4)-galactan and a specialized form of type II arabinogalactan are trapped by cellulose microfibrils specifically in tension wood and, thus, are the main candidate polymers for the generation of tensional stresses by the entrapment mechanism. We also found high β-galactosidase activity accompanying tension wood differentiation and propose a testable hypothesis that such activity might regulate galactan entrapment and, thus, mechanical properties of cell walls in tension wood. © 2015 American Society of Plant Biologists. All Rights Reserved.

Broadband diffuse optical characterization of elastin for biomedical applications.

PubMed

Konugolu Venkata Sekar, Sanathana; Beh, Joo Sin; Farina, Andrea; Dalla Mora, Alberto; Pifferi, Antonio; Taroni, Paola

2017-10-01

Elastin is a key structural protein of dynamic connective tissues widely found in the extracellular matrix of skin, arteries, lungs and ligaments. It is responsible for a range of diseases related to aging of biological tissues. The optical characterization of elastin can open new opportunities for its investigation in biomedical studies. In this work, we present the absorption spectra of elastin using a broadband (550-1350nm) diffuse optical spectrometer. Distortions caused by fluorescence and finite bandwidth of the laser source on estimated absorption were effectively accounted for in measurements and data analysis and compensated. A comprehensive summary and comparison between collagen and elastin is presented, highlighting distinct features for its accurate quantification in biological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Hemizygosity at the elastin locus and clinical features of Williams syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morimoto, Y; Kuwano, A.; Kuwajima, K.

1994-09-01

Williams syndrome is a recognizable syndrome characterized by distinctive facial appearance, gregarious personality, mental retardation, congenital heart defect, particularly supravalvular aortic stenosis (SVAS), and joint limitation. SVAS is an autosomal vascular disorder and the elastin gene was disrupted in patients with SVAS. Ewat et al. reported that hemizygosity at the elastin locus was detected in four familial and five sporadic cases of Williams syndrome. However, three patients did not have SVAS. We reconfirmed hemizygosity at the elastin locus in five patients with typical clinical features of Williams syndrome. Hemizygosity was detected in four cases with SVAS. However, one patient withmore » distinctive facial appearance and typical Williams syndrome personality had two alleles of the elastin gene, but he did not have the congenital heart anomaly. Williams syndrome is thought to be a contiguous gene disorder. Thus, our data suggest that the elastin gene is responsible for the vascular defect in patients with Williams syndrome, and flanking genes are responsible for characteristic facial appearance and personality.« less

GABA promotes elastin synthesis and elastin fiber formation in normal human dermal fibroblasts (HDFs).

PubMed

Uehara, Eriko; Hokazono, Hideki; Hida, Mariko; Sasaki, Takako; Yoshioka, Hidekatsu; Matsuo, Noritaka

2017-06-01

The multiple physiological effects of γ-aminobutyric acid (GABA) as a functional food component have been recently reported. We previously reported that GABA upregulated the expression of type I collagen in human dermal fibroblasts (HDFs), and that oral administration of GABA significantly increased skin elasticity. However, details of the regulatory mechanism still remain unknown. In this study, we further examined the effects of GABA on elastin synthesis and elastin fiber formation in HDFs. Real-time PCR indicated that GABA significantly increased the expression of tropoelastin transcript in a dose-dependent manner. Additionally, the expression of fibrillin-1, fibrillin-2, and fibulin-5/DANCE, but not lysyl oxidase and latent transforming factor-β-binding protein 4, were also significantly increased in HDFs. Finally, immunohistochemical analysis confirmed that treatment with GABA dramatically increased the formation of elastic fibers in HDFs. Taken together, our results showed that GABA improves skin elasticity in HDFs by upregulating elastin synthesis and elastin fiber formation.

Elastin in the human intervertebral disk. A histological and biochemical study comparing it with elastin in the human yellow ligament.

PubMed

Mikawa, Y; Hamagami, H; Shikata, J; Yamamuro, T

1986-01-01

The elastic fiber and elastin in the human yellow ligament and intervertebral disk were studied histologically and biochemically. The elastic fiber in the human intervertebral disk, which until now had not been clearly identified microscopically, was observed clearly. We found the distribution of the elastic fiber in the intervertebral disk to be very sparse and irregular, and its diameter was small, being about one-tenth of that found in the yellow ligament. The elastin contents of the yellow ligament and intervertebral disk were 46.7% +/- 0.9% and 1.7% +/- 0.2% respectively (mean +/- SE) of the total dry weight. The amino acid composition of elastin in the yellow ligament is similar to that of other tissue, as reported in the literature; however, that found in the intervertebral disk is significantly different. It would appear, therefore, that the elastin in the intervertebral disk is of a different type from that found elsewhere.

Elastin Is Differentially Regulated by Pressure Therapy in a Porcine Model of Hypertrophic Scar.

PubMed

Carney, Bonnie C; Liu, Zekun; Alkhalil, Abdulnaser; Travis, Taryn E; Ramella-Roman, Jessica; Moffatt, Lauren T; Shupp, Jeffrey W

Beneficial effects of pressure therapy for hypertrophic scars have been reported, but the mechanisms of action are not fully understood. This study evaluated elastin and its contribution to scar pliability. The relationship between changes in Vancouver Scar Scale (VSS) scores of pressure-treated scars and differential regulation of elastin was assessed. Hypertrophic scars were created and assessed weekly using VSS and biopsy procurement. Pressure treatment began on day 70 postinjury. Treated scars were compared with untreated shams. Treatment lasted 2 weeks, through day 84, and scars were assessed weekly through day 126. Transcript and protein levels of elastin were quantified. Pressure treatment resulted in lower VSS scores compared with sham-treated scars. Pliability (VSSP) was a key contributor to this difference. At day 70 pretreatment, VSSP = 2. Without treatment, sham-treated scars became less pliable, while pressure-treated scars became more pliable. The percentage of elastin in scars at day 70 was higher than in uninjured skin. Following treatment, the percentage of elastin increased and continued to increase through day 126. Untreated sham scars did not show a similar increase. Quantification of Verhoeff-Van Gieson staining corroborated the findings and immunofluorescence revealed the alignment of elastin fibers. Pressure treatment results in increased protein level expression of elastin compared with sham-untreated scars. These findings further characterize the extracellular matrix's response to the application of pressure as a scar treatment, which will contribute to the refinement of rehabilitation practices and ultimately improvements in functional and psychosocial outcomes for patients.

Details of the Collagen and Elastin Architecture in the Human Limbal Conjunctiva, Tenon's Capsule and Sclera Revealed by Two-Photon Excited Fluorescence Microscopy.

PubMed

Park, Choul Yong; Marando, Catherine M; Liao, Jason A; Lee, Jimmy K; Kwon, Jiwon; Chuck, Roy S

2016-10-01

To investigate the architecture and distribution of collagen and elastin in human limbal conjunctiva, Tenon's capsule, and sclera. The limbal conjunctiva, Tenon's capsule, and sclera of human donor corneal buttons were imaged with an inverted two-photon excited fluorescence microscope. No fixation process was necessary. The laser (Ti:sapphire) was tuned at 850 nm for two-photon excitation. Backscatter signals of second harmonic generation (SHG) and autofluorescence (AF) were collected through a 425/30-nm and a 525/45-nm emission filter, respectively. Multiple, consecutive, and overlapping (z-stack) images were acquired. Collagen signals were collected with SHG, whereas elastin signals were collected with AF. The size and density of collagen bundles varied widely depending on depth: increasing from conjunctiva to sclera. In superficial image planes, collagen bundles were <10 μm in width, in a loose, disorganized arrangement. In deeper image planes (episclera and superficial sclera), collagen bundles were thicker (near 100 μm in width) and densely packed. Comparatively, elastin fibers were thinner and sparse. The orientation of elastin fibers was independent of collagen fibers in superficial layers; but in deep sclera, elastin fibers wove through collagen interbundle gaps. At the limbus, both collagen and elastin fibers were relatively compact and were distributed perpendicular to the limbal annulus. Two-photon excited fluorescence microscopy has enabled us to understand in greater detail the collagen and elastin architecture of the human limbal conjunctiva, Tenon's capsule, and sclera.

Unraveling cellulose microfibrils: a twisted tale

USDA-ARS?s Scientific Manuscript database

Molecular dynamics (MD) simulations of hydrated cellulose microfibrils are attractive to the textiles industry for their capacity to characterize water interactions with cotton fiber, as well as to the biofuels industry for their potential to provide insight toward efficient mechanisms for conversio...

Viscoelastic properties of microfibrillated cellulose (MFC) produced from agricultural residue corn stover

USDA-ARS?s Scientific Manuscript database

The rheological properties of microfibrillated cellulose (MFC) produced from agricultural residue corn stover were investigated. The corn stover MFC gels exhibited concentration-dependent viscoelastic properties. Higher corn stover MFC concentrations resulted in stronger viscoelastic properties. Th...

Viscoelastic properties of microfibrillated cellulose (MFC) produced from agricultural residue corn stover

USDA-ARS?s Scientific Manuscript database

The rheological properties of microfibrillated cellulose (MFC) produced from agricultural residue corn stover were investigated. The corn stover MFC gels exhibited concentration-dependent viscoelastic solid properties. Higher corn stover MFC concentrations resulted in stronger viscoelastic propertie...

Origin of chiral interactions in cellulose supra-molecular microfibrils.

PubMed

Khandelwal, Mudrika; Windle, Alan

2014-06-15

The formation of a chiral-nematic phase from cellulose nanowhiskers has been frequently reported in the literature. The most popular theory used to explain the chiral interactions is that of twisted morphology of cellulose nanowhiskers. Two possible origins of twist have been suggested: the intrinsic chirality of cellulose chains and result of interaction of chiral surfaces. High resolution SEM and AFM have been used to locate twists in cellulose microfibrils and nanowhiskers. The origin of the twisted morphology in cellulose microfibrils has been studied with reference to the protein aggregation theory. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impaired cellulose synthase guidance leads to stem torsion and twists phyllotactic patterns in Arabidopsis.

PubMed

Landrein, Benoît; Lathe, Rahul; Bringmann, Martin; Vouillot, Cyril; Ivakov, Alexander; Boudaoud, Arezki; Persson, Staffan; Hamant, Olivier

2013-05-20

The parallel alignment of stiff cellulose microfibrils in plant-cell walls mediates anisotropic growth. This is largely controlled by cortical microtubules, which drive the insertion and trajectory of the cellulose synthase (CESA) complex at the plasma membrane. The CESA interactive protein 1 (CSI1) acts as a physical linker between CESA and cortical microtubules. Here we show that the inflorescence stems of csi1 mutants exhibit subtle right-handed torsion. Because cellulose deposition is largely uncoupled from cortical microtubules in csi1, we hypothesize that strictly transverse deposition of microfibrils in the wild-type is replaced by a helical orientation of uniform handedness in the mutant and that the helical microfibril alignment generates torsion. Interestingly, both elastic and viscous models for an expanding cell predict that a net helical orientation of microfibrils gives rise to a torque. We indeed observed tilted microfibrils in csi1 cells, and the torsion was almost absent in a csi1 prc1 background with impaired cellulose synthesis. In addition, the stem torsion led to a novel bimodal and robust phyllotactic pattern in the csi1 mutant, illustrating how growth perturbations can replace one robust mathematical pattern with a different, equally robust pattern. Copyright © 2013 Elsevier Ltd. All rights reserved.

Computational study of packing a collagen-like molecule: quasi-hexagonal vs "Smith" collagen microfibril model.

PubMed

Lee, J; Scheraga, H A; Rackovsky, S

1996-01-01

The lateral packing of a collagen-like molecule, CH3CO-(Gly-L-Pro-L-Pro)4-NHCH3, has been examined by energy minimization with the ECEPP/3 force field. Two current packing models, the Smith collagen microfibril twisted equilateral pentagonal model and the quasi-hexagonal packing model, have been extensively investigated. In treating the Smith microfibril model, energy minimization was carried out on various conformations including those with the symmetry of equivalent packing, i.e., in which the triple helices were arranged equivalently with respect to each other. Both models are based on the experimental observation of the characteristic axial periodicity, D = 67 nm, of light and dark bands, indicating that, if any superstructure exists, it should consist of five triple helices. The quasi-hexagonal packing structure is found to be energetically more favorable than the Smith microfibril model by as much as 31.2 kcal/mol of five triple helices. This is because the quasi-hexagonal packing geometry provides more nonbonded interaction possibilities between triple helices than does the Smith microfibril geometry. Our results are consistent with recent x-ray studies with synthetic collagen-like molecules and rat tail tendon, in which the data were interpreted as being consistent with either a quasi-hexagonal or a square-triangular structure.

COBRA, an Arabidopsis Extracellular Glycosyl-Phosphatidyl Inositol-Anchored Protein, Specifically Controls Highly Anisotropic Expansion through Its Involvement in Cellulose Microfibril OrientationW⃞

PubMed Central

Roudier, François; Fernandez, Anita G.; Fujita, Miki; Himmelspach, Regina; Borner, Georg H.H.; Schindelman, Gary; Song, Shuang; Baskin, Tobias I.; Dupree, Paul; Wasteneys, Geoffrey O.; Benfey, Philip N.

2005-01-01

The orientation of cell expansion is a process at the heart of plant morphogenesis. Cellulose microfibrils are the primary anisotropic material in the cell wall and thus are likely to be the main determinant of the orientation of cell expansion. COBRA (COB) has been identified previously as a potential regulator of cellulose biogenesis. In this study, characterization of a null allele, cob-4, establishes the key role of COB in controlling anisotropic expansion in most developing organs. Quantitative polarized-light and field-emission scanning electron microscopy reveal that loss of anisotropic expansion in cob mutants is accompanied by disorganization of the orientation of cellulose microfibrils and subsequent reduction of crystalline cellulose. Analyses of the conditional cob-1 allele suggested that COB is primarily implicated in microfibril deposition during rapid elongation. Immunodetection analysis in elongating root cells revealed that, in agreement with its substitution by a glycosylphosphatidylinositol anchor, COB was polarly targeted to both the plasma membrane and the longitudinal cell walls and was distributed in a banding pattern perpendicular to the longitudinal axis via a microtubule-dependent mechanism. Our observations suggest that COB, through its involvement in cellulose microfibril orientation, is an essential factor in highly anisotropic expansion during plant morphogenesis. PMID:15849274

Cellulose microfibril orientation of Picea abies and its variability at the micron-level determined by Raman imaging.

PubMed

Gierlinger, Notburga; Luss, Saskia; König, Christian; Konnerth, Johannes; Eder, Michaela; Fratzl, Peter

2010-01-01

The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns. Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle). By changing the laser polarization direction in 3 degrees steps, the dependency between cellulose and laser orientation direction was investigated. Orientation-dependent changes of band height ratios and spectra were described by quadratic linear regression and partial least square regressions, respectively. Using the models and regressions with high coefficients of determination (R(2) > 0.99) microfibril orientation was predicted in the S1 and S2 layers distinguished by the Raman imaging approach in cross-sections of spruce normal, opposite, and compression wood. The determined microfibril angle (MFA) in the different S2 layers ranged from 0 degrees to 49.9 degrees and was in coincidence with X-ray diffraction determination. With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues.

COBRA, an Arabidopsis extracellular glycosyl-phosphatidyl inositol-anchored protein, specifically controls highly anisotropic expansion through its involvement in cellulose microfibril orientation.

PubMed

Roudier, François; Fernandez, Anita G; Fujita, Miki; Himmelspach, Regina; Borner, Georg H H; Schindelman, Gary; Song, Shuang; Baskin, Tobias I; Dupree, Paul; Wasteneys, Geoffrey O; Benfey, Philip N

2005-06-01

The orientation of cell expansion is a process at the heart of plant morphogenesis. Cellulose microfibrils are the primary anisotropic material in the cell wall and thus are likely to be the main determinant of the orientation of cell expansion. COBRA (COB) has been identified previously as a potential regulator of cellulose biogenesis. In this study, characterization of a null allele, cob-4, establishes the key role of COB in controlling anisotropic expansion in most developing organs. Quantitative polarized-light and field-emission scanning electron microscopy reveal that loss of anisotropic expansion in cob mutants is accompanied by disorganization of the orientation of cellulose microfibrils and subsequent reduction of crystalline cellulose. Analyses of the conditional cob-1 allele suggested that COB is primarily implicated in microfibril deposition during rapid elongation. Immunodetection analysis in elongating root cells revealed that, in agreement with its substitution by a glycosylphosphatidylinositol anchor, COB was polarly targeted to both the plasma membrane and the longitudinal cell walls and was distributed in a banding pattern perpendicular to the longitudinal axis via a microtubule-dependent mechanism. Our observations suggest that COB, through its involvement in cellulose microfibril orientation, is an essential factor in highly anisotropic expansion during plant morphogenesis.

Extraction and characterization of elastin from poultry skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadalian, Mehdi; Yusop, Salma Mohamad; Mustapha, Wan Aida Wan

2013-11-27

Poultry by-products have a great economic potential that need to be exploited. Poultry skin could be utilized to produce elastin, which is often incorporated in the production of functional food or medicine due to its antioxidative properties. This study was conducted to determine the physicochemical and microstructural characteristics of elastins isolated from broiler and spent hen skin. Analyses including proximate and amino acid composition along with transmission electron microscopy (TEM) were carried out. In this study, elastin was successfully extracted from broiler and spent hen skin using three successive solvents extract of NaCl, acetone and NaOH respectively. It was apparentmore » that the fat content of extracted elastin from broiler skin was higher (P < 0.05) than spent hen’s, with both samples recording less than 1% fat. Moreover, broiler skin elastin also had a higher protein content (68.3%) than spent hen’s (67.8%). Both skin sources contained glycine as the major amino acid (19–20%), followed by glutamic acid, proline, alanine and arginine. The results of TEM indicated that the use of collagenase enzyme or further purification efforts should be incorporated along with the extraction methods used because of the presence of collagen and other debris in the resultant elastin.« less

Aortic microcalcification is associated with elastin fragmentation in Marfan syndrome.

PubMed

Wanga, Shaynah; Hibender, Stijntje; Ridwan, Yanto; van Roomen, Cindy; Vos, Mariska; van der Made, Ingeborg; van Vliet, Nicole; Franken, Romy; van Riel, Luigi Amjg; Groenink, Maarten; Zwinderman, Aeilko H; Mulder, Barbara Jm; de Vries, Carlie Jm; Essers, Jeroen; de Waard, Vivian

2017-11-01

Marfan syndrome (MFS) is a connective tissue disorder in which aortic rupture is the major cause of death. MFS patients with an aortic diameter below the advised limit for prophylactic surgery (<5 cm) may unexpectedly experience an aortic dissection or rupture, despite yearly monitoring. Hence, there is a clear need for improved prognostic markers to predict such aortic events. We hypothesize that elastin fragments play a causal role in aortic calcification in MFS, and that microcalcification serves as a marker for aortic disease severity. To address this hypothesis, we analysed MFS patient and mouse aortas. MFS patient aortic tissue showed enhanced microcalcification in areas with extensive elastic lamina fragmentation in the media. A causal relationship between medial injury and microcalcification was revealed by studies in vascular smooth muscle cells (SMCs); elastin peptides were shown to increase the activity of the calcification marker alkaline phosphatase (ALP) and reduce the expression of the calcification inhibitor matrix GLA protein in human SMCs. In murine Fbn1 C1039G/+ MFS aortic SMCs, Alpl mRNA and activity were upregulated as compared with wild-type SMCs. The elastin peptide-induced ALP activity was prevented by incubation with lactose or a neuraminidase inhibitor, which inhibit the elastin receptor complex, and a mitogen-activated protein kinase kinase-1/2 inhibitor, indicating downstream involvement of extracellular signal-regulated kinase-1/2 (ERK1/2) phosphorylation. Histological analyses in MFS mice revealed macrocalcification in the aortic root, whereas the ascending aorta contained microcalcification, as identified with the near-infrared fluorescent bisphosphonate probe OsteoSense-800. Significantly, microcalcification correlated strongly with aortic diameter, distensibility, elastin breaks, and phosphorylated ERK1/2. In conclusion, microcalcification co-localizes with aortic elastin degradation in MFS aortas of humans and mice, where elastin-derived peptides induce a calcification process in SMCs via the elastin receptor complex and ERK1/2 activation. We propose microcalcification as a novel imaging marker to monitor local elastin degradation and thus predict aortic events in MFS patients. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Exploiting CELLULOSE SYNTHASE (CESA) Class Specificity to Probe Cellulose Microfibril Biosynthesis.

PubMed

Kumar, Manoj; Mishra, Laxmi; Carr, Paul; Pilling, Michael; Gardner, Peter; Mansfield, Shawn D; Turner, Simon

2018-05-01

Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfibrils is at least partly determined by the structure of the cellulose synthase complex. In higher plants, this complex is composed of 18 to 24 catalytic subunits known as CELLULOSE SYNTHASE A (CESA) proteins. Three different classes of CESA proteins are required for cellulose synthesis and for secondary cell wall cellulose biosynthesis these classes are represented by CESA4, CESA7, and CESA8. To probe the relationship between CESA proteins and microfibril structure, we created mutant cesa proteins that lack catalytic activity but retain sufficient structural integrity to allow assembly of the cellulose synthase complex. Using a series of Arabidopsis ( Arabidopsis thaliana ) mutants and genetic backgrounds, we found consistent differences in the ability of these mutant cesa proteins to complement the cellulose-deficient phenotype of the cesa null mutants. The best complementation was observed with catalytically inactive cesa4, while the equivalent mutation in cesa8 exhibited significantly lower levels of complementation. Using a variety of biophysical techniques, including solid-state nuclear magnetic resonance and Fourier transform infrared microscopy, to study these mutant plants, we found evidence for changes in cellulose microfibril structure, but these changes largely correlated with cellulose content and reflected differences in the relative proportions of primary and secondary cell walls. Our results suggest that individual CESA classes have similar roles in determining cellulose microfibril structure, and it is likely that the different effects of mutating members of different CESA classes are the consequence of their different catalytic activity and their influence on the overall rate of cellulose synthesis. © 2018 American Society of Plant Biologists. All Rights Reserved.

Ultrastructural organization of connective tissue microfibrils in the posterior chamber of the eye in vivo and in vitro.

PubMed

Inoue, S

1995-02-01

The ultrastructural organization of connective tissue microfibrils was studied in the mouse eye and also by means of in vitro experiments for reconstituting microfibrils. In the posterior chamber of the eye of the C57BL/6J mouse, 3 nm-wide ribbon-like double-tracked structures were present and were periodically associated on either side with 3.5 nm-wide particulate structures identified as pentosomes, the subunits of amyloid P component (AP). At certain sites, such composite structures were observed in various stages of helical winding, and in these helices, pentosomes were preferentially localized internally. In helices in the final stages of winding, the resulting rods appeared increasingly similar to those of microfibrils. In experiments in vitro, incubation of chondroitin sulfate proteoglycan (CSPG) in TRIS buffer, pH 7.4, at 35 degrees C for 1 h produced random aggregates of 3 nm-wide double-tracked structures similar to those observed in the eye. Co-incubation of CSPG and AP resulted in the formation of rod-like structures arranged parallel to one another in approximately 50 nm-thick sheet-like layers. These rods were ultrastructurally similar to microfibrils and were made up of helically wound, 3 nm-wide double-tracked structures containing pentosomes within their core. The results of in vivo as well as in vitro experiments suggest the possibility that the connective tissue microfibril is composed of helically wound, CSPG-containing, 3 nm-wide double-tracked structures periodically associated with pentosomes which, as the helix becomes progressively tighter, fit with one another at the core of the helix to form successive 8.5 nm-wide disks of AP segments.

Exploiting CELLULOSE SYNTHASE (CESA) Class Specificity to Probe Cellulose Microfibril Biosynthesis1[OPEN

PubMed Central

Mishra, Laxmi; Carr, Paul; Gardner, Peter

2018-01-01

Cellulose microfibrils are the basic units of cellulose in plants. The structure of these microfibrils is at least partly determined by the structure of the cellulose synthase complex. In higher plants, this complex is composed of 18 to 24 catalytic subunits known as CELLULOSE SYNTHASE A (CESA) proteins. Three different classes of CESA proteins are required for cellulose synthesis and for secondary cell wall cellulose biosynthesis these classes are represented by CESA4, CESA7, and CESA8. To probe the relationship between CESA proteins and microfibril structure, we created mutant cesa proteins that lack catalytic activity but retain sufficient structural integrity to allow assembly of the cellulose synthase complex. Using a series of Arabidopsis (Arabidopsis thaliana) mutants and genetic backgrounds, we found consistent differences in the ability of these mutant cesa proteins to complement the cellulose-deficient phenotype of the cesa null mutants. The best complementation was observed with catalytically inactive cesa4, while the equivalent mutation in cesa8 exhibited significantly lower levels of complementation. Using a variety of biophysical techniques, including solid-state nuclear magnetic resonance and Fourier transform infrared microscopy, to study these mutant plants, we found evidence for changes in cellulose microfibril structure, but these changes largely correlated with cellulose content and reflected differences in the relative proportions of primary and secondary cell walls. Our results suggest that individual CESA classes have similar roles in determining cellulose microfibril structure, and it is likely that the different effects of mutating members of different CESA classes are the consequence of their different catalytic activity and their influence on the overall rate of cellulose synthesis. PMID:29523715

Deficient Circumferential Growth Is the Primary Determinant of Aortic Obstruction Attributable to Partial Elastin Deficiency.

PubMed

Jiao, Yang; Li, Guangxin; Korneva, Arina; Caulk, Alexander W; Qin, Lingfeng; Bersi, Matthew R; Li, Qingle; Li, Wei; Mecham, Robert P; Humphrey, Jay D; Tellides, George

2017-05-01

Williams syndrome is characterized by obstructive aortopathy attributable to heterozygous loss of ELN , the gene encoding elastin. Lesions are thought to result primarily from excessive smooth muscle cell (SMC) proliferation and consequent medial expansion, although an initially smaller caliber and increased stiffness of the aorta may contribute to luminal narrowing. The relative contributions of such abnormalities to the obstructive phenotype had not been defined. We quantified determinants of luminal stenosis in thoracic aortas of Eln -/- mice incompletely rescued by human ELN . Moderate obstruction was largely because of deficient circumferential growth, most prominently of ascending segments, despite increased axial growth. Medial thickening was evident in these smaller diameter elastin-deficient aortas, with medial area similar to that of larger diameter control aortas. There was no difference in cross-sectional SMC number between mutant and wild-type genotypes at multiple stages of postnatal development. Decreased elastin content was associated with medial fibrosis and reduced aortic distensibility because of increased structural stiffness but preserved material stiffness. Elastin-deficient SMCs exhibited greater contractile-to-proliferative phenotypic modulation in vitro than in vivo. We confirmed increased medial collagen without evidence of increased medial area or SMC number in a small ascending aorta with thickened media of a Williams syndrome subject. Deficient circumferential growth is the predominant mechanism for moderate obstructive aortic disease resulting from partial elastin deficiency. Our findings suggest that diverse aortic manifestations in Williams syndrome result from graded elastin content, and SMC hyperplasia causing medial expansion requires additional elastin loss superimposed on ELN haploinsufficiency. © 2017 American Heart Association, Inc.

Fourier transform infrared spectroscopy to quantify collagen and elastin in an in vitro model of extracellular matrix degradation in aorta.

PubMed

Cheheltani, Rabee; McGoverin, Cushla M; Rao, Jayashree; Vorp, David A; Kiani, Mohammad F; Pleshko, Nancy

2014-06-21

Extracellular matrix (ECM) is a key component and regulator of many biological tissues including aorta. Several aortic pathologies are associated with significant changes in the composition of the matrix, especially in the content, quality and type of aortic structural proteins, collagen and elastin. The purpose of this study was to develop an infrared spectroscopic methodology that is comparable to biochemical assays to quantify collagen and elastin in aorta. Enzymatically degraded porcine aorta samples were used as a model of ECM degradation in abdominal aortic aneurysm (AAA). After enzymatic treatment, Fourier transform infrared (FTIR) spectra of the aortic tissue were acquired by an infrared fiber optic probe (IFOP) and FTIR imaging spectroscopy (FT-IRIS). Collagen and elastin content were quantified biochemically and partial least squares (PLS) models were developed to predict collagen and elastin content in aorta based on FTIR spectra. PLS models developed from FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (RMSE of validation = 8.4% and 11.1% of the range respectively), and IFOP spectra were successfully used to predict elastin content (RMSE = 11.3% of the range). The PLS regression coefficients from the FT-IRIS models were used to map collagen and elastin in tissue sections of degraded porcine aortic tissue as well as a human AAA biopsy tissue, creating a similar map of each component compared to histology. These results support further application of FTIR spectroscopic techniques for evaluation of AAA tissues.

Insoluble elastin reduces collagen scaffold stiffness, improves viscoelastic properties, and induces a contractile phenotype in smooth muscle cells.

PubMed

Ryan, Alan J; O'Brien, Fergal J

2015-12-01

Biomaterials with the capacity to innately guide cell behaviour while also displaying suitable mechanical properties remain a challenge in tissue engineering. Our approach to this has been to utilise insoluble elastin in combination with collagen as the basis of a biomimetic scaffold for cardiovascular tissue engineering. Elastin was found to markedly alter the mechanical and biological response of these collagen-based scaffolds. Specifically, during extensive mechanical assessment elastin was found to reduce the specific tensile and compressive moduli of the scaffolds in a concentration dependant manner while having minimal effect on scaffold microarchitecture with both scaffold porosity and pore size still within the ideal ranges for tissue engineering applications. However, the viscoelastic properties were significantly improved with elastin addition with a 3.5-fold decrease in induced creep strain, a 6-fold increase in cyclical strain recovery, and with a four-parameter viscoelastic model confirming the ability of elastin to confer resistance to long term deformation/creep. Furthermore, elastin was found to result in the modulation of SMC phenotype towards a contractile state which was determined via reduced proliferation and significantly enhanced expression of early (α-SMA), mid (calponin), and late stage (SM-MHC) contractile proteins. This allows the ability to utilise extracellular matrix proteins alone to modulate SMC phenotype without any exogenous factors added. Taken together, the ability of elastin to alter the mechanical and biological response of collagen scaffolds has led to the development of a biomimetic biomaterial highly suitable for cardiovascular tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impact of elastin incorporation into electrochemically aligned collagen fibers on mechanical properties and smooth muscle cell phenotype.

PubMed

Nguyen, Thuy-Uyen; Bashur, Chris A; Kishore, Vipuil

2016-03-17

Application of tissue-engineered vascular grafts (TEVGs) for the replacement of small-diameter arteries is limited due to thrombosis and intimal hyperplasia. Previous studies have attempted to address the limitations of TEVGs by developing scaffolds that mimic the composition (collagen and elastin) of native arteries to better match the mechanical properties of the graft with the native tissue. However, most existing scaffolds do not recapitulate the aligned topography of the collagen fibers found in native vessels. In the current study, based on the principles of isoelectric focusing, two different types of elastin (soluble and insoluble) were incorporated into highly oriented electrochemically aligned collagen (ELAC) fibers and the effect of elastin incorporation on the mechanical properties of the ELAC fibers and smooth muscle cell (SMC) phenotype was investigated. The results indicate that elastin incorporation significantly decreased the modulus of ELAC fibers to converge upon that of native vessels. Further, a significant increase in yield strain and decrease in Young's modulus was observed on all fibers post SMC culture compared with before the culture. Real-time polymerase chain reaction results showed a significant increase in the expression of α-smooth muscle actin and calponin on ELAC fibers with insoluble elastin, suggesting that incorporation of insoluble elastin induces a contractile phenotype in SMCs after two weeks of culture on ELAC fibers. Immunofluorescence results showed that calponin expression increased with time on all fibers. In conclusion, insoluble elastin incorporated ELAC fibers have the potential to be used for the development of functional TEVGs for the repair and replacement of small-diameter arteries.

Fourier Transform Infrared Spectroscopy to Quantify Collagen and Elastin in an In Vitro Model of Extracellular Matrix Degradation in Aorta

PubMed Central

Cheheltani, Rabee; McGoverin, Cushla M.; Rao, Jayashree; Vorp, David A.; Kiani, Mohammad F.; Pleshko, N.

2014-01-01

Extracellular matrix (ECM) is a key component and regulator of many biological tissues including aorta. Several aortic pathologies are associated with significant changes in the composition of the matrix, especially in the content, quality and type of aortic structural proteins, collagen and elastin. The purpose of this study was to develop an infrared spectroscopic methodology that is comparable to biochemical assays to quantify collagen and elastin in aorta. Enzymatically degraded porcine aorta samples were used as a model of ECM degradation in abdominal aortic aneurysm (AAA). After enzymatic treatment, Fourier transform infrared (FTIR) spectra of the aortic tissue were acquired by an infrared fiber optic probe (IFOP) and FTIR imaging spectroscopy (FT-IRIS). Collagen and elastin content were quantified biochemically and partial least squares (PLS) models were developed to predict collagen and elastin content in aorta based on FTIR spectra. PLS models developed from FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (RMSE of validation = 8.4% and 11.1% of the range respectively), and IFOP spectra were successfully used to predict elastin content (RMSE = 11.3% of the range). The PLS regression coefficients from the FT-IRIS models were used to map collagen and elastin in tissue sections of degraded porcine aortic tissue as well as a human AAA biopsy tissue, creating a similar map of each component compared to histology. These results support further application of FTIR spectroscopic techniques for evaluation of AAA tissues. PMID:24761431

Elastin overexpression by cell-based gene therapy preserves matrix and prevents cardiac dilation

PubMed Central

Li, Shu-Hong; Sun, Zhuo; Guo, Lily; Han, Mihan; Wood, Michael F G; Ghosh, Nirmalya; Alex Vitkin, I; Weisel, Richard D; Li, Ren-Ke

2012-01-01

After a myocardial infarction, thinning and expansion of the fibrotic scar contribute to progressive heart failure. The loss of elastin is a major contributor to adverse extracellular matrix remodelling of the infarcted heart, and restoration of the elastic properties of the infarct region can prevent ventricular dysfunction. We implanted cells genetically modified to overexpress elastin to re-establish the elastic properties of the infarcted myocardium and prevent cardiac failure. A full-length human elastin cDNA was cloned, subcloned into an adenoviral vector and then transduced into rat bone marrow stromal cells (BMSCs). In vitro studies showed that BMSCs expressed the elastin protein, which was deposited into the extracellular matrix. Transduced BMSCs were injected into the infarcted myocardium of adult rats. Control groups received either BMSCs transduced with the green fluorescent protein gene or medium alone. Elastin deposition in the infarcted myocardium was associated with preservation of myocardial tissue structural integrity (by birefringence of polarized light; P < 0.05 versus controls). As a result, infarct scar thickness and diastolic compliance were maintained and infarct expansion was prevented (P < 0.05 versus controls). Over a 9-week period, rats implanted with BMSCs demonstrated better cardiac function than medium controls; however, rats receiving BMSCs overexpressing elastin showed the greatest functional improvement (P < 0.01). Overexpression of elastin in the infarcted heart preserved the elastic structure of the extracellular matrix, which, in turn, preserved diastolic function, prevented ventricular dilation and preserved cardiac function. This cell-based gene therapy provides a new approach to cardiac regeneration. PMID:22435995

Elastin Shapes Small Molecule Distribution in Lymph Node Conduits.

PubMed

Lin, Yujia; Louie, Dante; Ganguly, Anutosh; Wu, Dequan; Huang, Peng; Liao, Shan

2018-05-01

The spatial and temporal Ag distribution determines the subsequent T cell and B cell activation at the distinct anatomical locations in the lymph node (LN). It is well known that LN conduits facilitate small Ag distribution in the LN, but the mechanism of how Ags travel along LN conduits remains poorly understood. In C57BL/6J mice, using FITC as a fluorescent tracer to study lymph distribution in the LN, we found that FITC preferentially colocalized with LN capsule-associated (LNC) conduits. Images generated using a transmission electron microscope showed that LNC conduits are composed of solid collagen fibers and are wrapped with fibroblastic cells. Superresolution images revealed that high-intensity FITC is typically colocalized with elastin fibers inside the LNC conduits. Whereas tetramethylrhodamine isothiocyanate appears to enter LNC conduits as effectively as FITC, fluorescently-labeled Alexa-555-conjugated OVA labels significantly fewer LNC conduits. Importantly, injection of Alexa-555-conjugated OVA with LPS substantially increases OVA distribution along elastin fibers in LNC conduits, indicating immune stimulation is required for effective OVA traveling along elastin in LN conduits. Finally, elastin fibers preferentially surround lymphatic vessels in the skin and likely guide fluid flow to the lymphatic vessels. Our studies demonstrate that fluid or small molecules are preferentially colocalized with elastin fibers. Although the exact mechanism of how elastin fibers regulate Ag trafficking remains to be explored, our results suggest that elastin can be a potentially new target to direct Ag distribution in the LN during vaccine design. Copyright © 2018 by The American Association of Immunologists, Inc.

Tyrosinase-Mediated Construction of a Silk Fibroin/Elastin Nanofiber Bioscaffold.

PubMed

Hong, Yanqing; Zhu, Xueke; Wang, Ping; Fu, Haitian; Deng, Chao; Cui, Li; Wang, Qiang; Fan, Xuerong

2016-04-01

Elastin has characteristics of elasticity, biological activity, and mechanical stability. In the present work, tyrosinase-mediated construction of a bioscaffold with silk fibroin and elastin was carried out, aiming at developing a novel medical biomaterial. The efficiency of enzymatic oxidation of silk fibroin and the covalent reaction between fibroin and elastin were examined by spectrophotometry, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and size exclusion chromatography (SEC). The properties of composite air-dried and nanofiber scaffolds were investigated. The results reveal that elastin was successfully bonded to silk fibroins, resulting in an increase in molecular weight of fibroin proteins. ATR-FTIR spectra indicated that tyrosinase treatment impacted the conformational structure of fibroin-based membrane. The thermal behaviors and mechanical properties of the tyrosinase-treated scaffolds were also improved compared with the untreated group. NIH/3T3 cells exhibited optimum densities when grown on the nanofiber scaffold, implying that the nanofiber scaffold has enhanced biocompatibility compared to the air-dried scaffold. A biological nanofiber scaffold constructed from tyrosinase-treated fibroin and elastin could potentially be utilized in biomedical applications.

Dissecting the molecular mechanism underlying the intimate relationship between cellulose microfibrils and cortical microtubules.

PubMed

Lei, Lei; Li, Shundai; Bashline, Logan; Gu, Ying

2014-01-01

A central question in plant cell development is how the cell wall determines directional cell expansion and therefore the final shape of the cell. As the major load-bearing component of the cell wall, cellulose microfibrils are laid down transversely to the axis of elongation, thus forming a spring-like structure that reinforces the cell laterally and while favoring longitudinal expansion in most growing cells. Mounting evidence suggests that cortical microtubules organize the deposition of cellulose microfibrils, but the precise molecular mechanisms linking microtubules to cellulose organization have remained unclear until the recent discovery of cellulose synthase interactive protein 1 , a linker protein between the cortical microtubules and the cellulose biosynthesizing machinery. In this review, we will focus on the intimate relationship between cellulose microfibrils and cortical microtubules, in particular, we will discuss microtubule arrangement and cell wall architecture, the linkage between cellulose synthase complexes and microtubules, and the feedback mechanisms between cell wall and microtubules.

Wide-angle x-ray scattering and solid-state nuclear magnetic resonance data combined to test models for cellulose microfibrils in mung bean cell walls.

PubMed

Newman, Roger H; Hill, Stefan J; Harris, Philip J

2013-12-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette.

Cytoskeleton-mediated templating of complex cellulose-scaffolded extracellular structure and its association with oikosins in the urochordate Oikopleura.

PubMed

Sagane, Yoshimasa; Hosp, Julia; Zech, Karin; Thompson, Eric M

2011-05-01

Oriented cellulose deposition is critical to plant patterning and models suggest microtubules constrain cellulose synthase movements through the plasma membrane. Though widespread in plants, urochordates are the only animals that synthesize cellulose. We characterized the distinctive cellulose microfibril scaffold of the larvacean house and its interaction with house structural proteins (oikosins). Targeted disruption of cytoskeletal elements, secretory pathways, and plasma membrane organization, suggested a working model for templating extracellular cellulose microfibrils from animal cells that shows both convergence and differences to plant models. Specialized cortical F-actin arrays template microfibril orientation and glycosylphosphatidylinositol-anchored proteins in lipid rafts may act as scaffolding proteins in microfibril elongation. Microtubules deliver and maintain cellulose synthase complexes to specific cell membrane sites rather than orienting their movement through the membrane. Oikosins are incorporated into house compartments directly above their corresponding cellular field of expression and interact with the cellulose scaffold to a variable extent.

Alteration of in vivo cellulose ribbon assembly by carboxymethylcellulose and other cellulose derivatives.

PubMed

Haigler, C H; White, A R; Brown, R M; Cooper, K M

1982-07-01

In vivo cellulose ribbon assembly by the Gram-negative bacterium Acetobacter xylinum can be altered by incubation in carboxymethylcellulose (CMC), a negatively charged water-soluble cellulose derivative, and also by incubation in a variety of neutral, water-soluble cellulose derivatives. In the presence of all of these substituted celluloses, normal fasciation of microfibril bundles to form the typical twisting ribbon is prevented. Alteration of ribbon assembly is most extensive in the presence of CMC, which often induces synthesis of separate, intertwining bundles of microfibrils. Freeze-etch preparations of the bacterial outer membrane suggest that particles that are thought to be associated with cellulose synthesis or extrusion may be specifically organized to mediate synthesis of microfibril bundles. These data support the previous hypothesis that the cellulose ribbon of A. xylinum is formed by a hierarchical, cell-directed, self-assembly process. The relationship of these results to the regulation of cellulose microfibril size and wall extensibility in plant cell walls is discussed.

Structural and biochemical changes in dermis of sea cucumber (Stichopus japonicus) during autolysis in response to cutting the body wall.

PubMed

Liu, Yu-Xin; Zhou, Da-Yong; Liu, Zi-Qiang; Lu, Ting; Song, Liang; Li, Dong-Mei; Dong, Xiu-Ping; Qi, Hang; Zhu, Bei-Wei; Shahidi, Fereidoon

2018-02-01

The autolysis of sea cucumber body wall is caused by endogenous proteolysis of its structural elements. However, changes in collagen fibrils, collagen fibres and microfibrils, the major structural elements in sea cucumber body wall during autolysis are less clear. Autolysis of sea cucumber (S. japonicus) was induced by cutting the body wall, and the structural and biochemical changes in its dermis were investigated using electron microscopy, differential scanning calorimetry, infrared spectroscopy, electrophoresis, and chemical analysis. During autolysis, both collagen fibres and microfibrils gradually degraded. In contrast, damage to microfibrils was more pronounced. Upon massive autolysis, collagen fibres disaggregated into collagen fibril bundles and individual fibrils due to the fracture of interfibrillar bridges. Meanwhile, excessive unfolding of collagen fibrils occurred. However, there was only slight damage to collagen monomers. Therefore, structural damage in collagen fibres, collagen fibrils and microfibrils rather than monomeric collagen accounts for autolysis of S. japonicus dermis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interplay Between Hydrophobic Effect and Dipole Interactions in Peptide Aggregation

NASA Astrophysics Data System (ADS)

Ganesan, Sai; Matysiak, Silvina

In the past decade, the development of various coarse-grained models for proteins have provided key insights into the driving forces in folding and aggregation.We recently developed a low resolution Water Explicit Polarizable PROtein coarse-grained Model by adding oppositely charged dummy particles inside protein backbone beads.With this model,we were able to achieve significant α/ β secondary structure content,without any added bias.We now extend the model to study peptide aggregation at hydrophobic-hydrophilic interface using elastin-like octapeptides (GV)4 as a model system.A condensation-ordering mechanism of aggregation is observed in water.Our results suggest that backbone interpeptide dipolar interactions,not hydrophobicity,plays a more significant role in fibril-like peptide aggregation.We observe a cooperative effect in hydrogen bonding or dipolar interactions, with increase in aggregate size in water and interface.Based on this cooperative effect, we provide a potential explanation for the observed nucleus size in peptide aggregation pathways.Without dipolar particles,peptide aggregation is not observed at the hydrophilic-hydrophobic interface.Thus,the presence of dipoles,not hydrophobicity plays a key role in aggregation observed at hydrophobic interfaces.

Effect of elastin-derived peptides on the production of tissue inhibitor of metalloproteinase-1, -2, and -3 and the ratios in various endothelial cell lines.

PubMed

Siemianowicz, Krzysztof; Likus, Wirginia; Francuz, Tomasz; Garczorz, Wojciech

2015-06-01

Tissue inhibitors of metalloproteinases (TIMPs) control the activity of metalloproteinases. Elastin-derived peptides (EDPs) are generated as a result of the degradation of elastin fibers. The EDPs bind to the elastin receptor and exert numerous biological effects. The aim of the present study was to compare the production of TIMP-1, TIMP-2 and TIMP-3 and their ratios in human endothelial cells (ECs) derived from three clinically important vascular localizations (coronary arteries, aorta and iliac artery), and evaluate the influence of a well-known EDP, κ-elastin. The highest concentration of TIMP-1 was identified in the aortic ECs, while the lowest concentration was observed in the ECs derived from the coronary artery. The opposite pattern was observed for TIMP-2 production. When the TIMP-3 concentration was analyzed in the three EC lines, no statistically significant differences were observed. Application of κ-elastin was found to decrease the TIMP-1 concentration in the aortic ECs, while an increase in the TIMP-1 concentration was observed in the ECs derived from the iliac artery. The most significant decrease in TIMP-2 concentration following κ-elastin administration was observed in the ECs obtained from the coronary arteries. Furthermore, the highest concentration of κ-elastin resulted in an increase in TIMP-3 production in the ECs derived from the coronary arteries. The following ratios of the TIMP concentrations were calculated: TIMP-1/TIMP-2, TIMP-1/TIMP-3 and TIMP-2/TIMP-3. Each ratio presented different values for the ECs obtained from the various localizations. In the majority of cases, the addition of κ-elastin did not significantly change these proportions. Therefore, these indicators may be characteristic features that can be used to describe ECs in various clinically important vascular localizations.

Effect of elastin-derived peptides on the production of tissue inhibitor of metalloproteinase-1, -2, and -3 and the ratios in various endothelial cell lines

PubMed Central

SIEMIANOWICZ, KRZYSZTOF; LIKUS, WIRGINIA; FRANCUZ, TOMASZ; GARCZORZ, WOJCIECH

2015-01-01

Tissue inhibitors of metalloproteinases (TIMPs) control the activity of metalloproteinases. Elastin-derived peptides (EDPs) are generated as a result of the degradation of elastin fibers. The EDPs bind to the elastin receptor and exert numerous biological effects. The aim of the present study was to compare the production of TIMP-1, TIMP-2 and TIMP-3 and their ratios in human endothelial cells (ECs) derived from three clinically important vascular localizations (coronary arteries, aorta and iliac artery), and evaluate the influence of a well-known EDP, κ-elastin. The highest concentration of TIMP-1 was identified in the aortic ECs, while the lowest concentration was observed in the ECs derived from the coronary artery. The opposite pattern was observed for TIMP-2 production. When the TIMP-3 concentration was analyzed in the three EC lines, no statistically significant differences were observed. Application of κ-elastin was found to decrease the TIMP-1 concentration in the aortic ECs, while an increase in the TIMP-1 concentration was observed in the ECs derived from the iliac artery. The most significant decrease in TIMP-2 concentration following κ-elastin administration was observed in the ECs obtained from the coronary arteries. Furthermore, the highest concentration of κ-elastin resulted in an increase in TIMP-3 production in the ECs derived from the coronary arteries. The following ratios of the TIMP concentrations were calculated: TIMP-1/TIMP-2, TIMP-1/TIMP-3 and TIMP-2/TIMP-3. Each ratio presented different values for the ECs obtained from the various localizations. In the majority of cases, the addition of κ-elastin did not significantly change these proportions. Therefore, these indicators may be characteristic features that can be used to describe ECs in various clinically important vascular localizations. PMID:26136968

Physiological regulation of extracellular matrix collagen and elastin in the arterial wall of rats by noradrenergic tone and angiotensin II.

PubMed

Dab, Houcine; Kacem, Kamel; Hachani, Rafik; Dhaouadi, Nadra; Hodroj, Wassim; Sakly, Mohsen; Randon, Jacques; Bricca, Giampiero

2012-03-01

The interactions between the effects of the sympathetic nervous system (SNS) and angiotensin II (ANG II) on vascular extracellular matrix (ECM) synthesis were determined in rats. The mRNA and protein content of collagen I, collagen III and elastin in the abdominal aorta (AA) and femoral artery (FA) was investigated in Wistar-Kyoto rats treated for 5 weeks with guanethidine, a sympathoplegic, losartan, an ANG II AT1 receptor (AT1R) blocker, or both. The effects of noradrenaline (NE) and ANG II on collagen III and elastin mRNA, and the receptor involved, were tested in cultured vascular smooth muscle cells (VSMCs) in vitro. Guanethidine increased collagen types I and III and decreased elastin, while losartan had an opposite effect, although without effect on collagen III. The combination of treatments abrogated changes induced by simple treatment with collagen I and elastin, but increased collagen III mRNA in AA and not in FA. NE stimulated collagen III mRNA via β receptors and elastin via α1 and α2 receptors. ANG II stimulated collagen III but inhibited elastin mRNA via AT1R. Overall, SNS and ANG II exert opposite and antagonistic effects on major components of ECM in the vascular wall. This may be of relevance for the choice of a therapeutic strategy in vascular diseases.

Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin.

PubMed

Muiznieks, Lisa D; Reichheld, Sean E; Sitarz, Eva E; Miao, Ming; Keeley, Fred W

2015-10-01

Elastin is a self-assembling extracellular matrix protein that provides elasticity to tissues. For entropic elastomers such as elastin, conformational disorder of the monomer building block, even in the polymeric form, is essential for elastomeric recoil. The highly hydrophobic monomer employs a range of strategies for maintaining disorder and flexibility within hydrophobic domains, particularly involving a minimum compositional threshold of proline and glycine residues. However, the native sequence of hydrophobic elastin domain 30 is uncharacteristically proline-poor and, as an isolated polypeptide, is susceptible to formation of amyloid-like structures comprised of stacked β-sheet. Here we investigated the biophysical and mechanical properties of multiple sets of elastin-like polypeptides designed with different numbers of proline-poor domain 30 from human or rat tropoelastins. We compared the contributions of these proline-poor hydrophobic sequences to self-assembly through characterization of phase separation, and to the tensile properties of cross-linked, polymeric materials. We demonstrate that length of hydrophobic domains and propensity to form β-structure, both affecting polypeptide chain flexibility and cross-link density, play key roles in modulating elastin mechanical properties. This study advances the understanding of elastin sequence-structure-function relationships, and provides new insights that will directly support rational approaches to the design of biomaterials with defined suites of mechanical properties. © 2015 Wiley Periodicals, Inc.

Ligand affinity of the 67-kD elastin/laminin binding protein is modulated by the protein's lectin domain: visualization of elastin/laminin-receptor complexes with gold-tagged ligands

PubMed Central

1991-01-01

Video-enhanced microscopy was used to examine the interaction of elastin- or laminin-coated gold particles with elastin binding proteins on the surface of live cells. By visualizing the binding events in real time, it was possible to determine the specificity and avidity of ligand binding as well as to analyze the motion of the receptor-ligand complex in the plane of the plasma membrane. Although it was difficult to interpret the rates of binding and release rigorously because of the possibility for multiple interactions between particles and the cell surface, relative changes in binding have revealed important aspects of the regulation of affinity of ligand-receptor interaction in situ. Both elastin and laminin were found to compete for binding to the cell surface and lactose dramatically decreased the affinity of the receptor(s) for both elastin and laminin. These findings were supported by in vitro studies of the detergent-solubilized receptor. Further, immobilization of the ligand-receptor complexes through binding to the cytoskeleton dramatically decreased the ability of bound particles to leave the receptor. The changes in the kinetics of ligand-coated gold binding to living cells suggest that both laminin and elastin binding is inhibited by lactose and that attachment of receptor to the cytoskeleton increases its affinity for the ligand. PMID:1848864

Elastin density: Link between histological and biomechanical properties of vaginal tissue in women with pelvic organ prolapse?

PubMed

de Landsheere, Laurent; Brieu, Mathias; Blacher, Silvia; Munaut, Carine; Nusgens, Betty; Rubod, Chrystèle; Noel, Agnès; Foidart, Jean-Michel; Nisolle, Michelle; Cosson, Michel

2016-04-01

The aim of the study was to correlate histological and biomechanical characteristics of the vaginal wall in women with pelvic organ prolapse (POP). Tissue samples were collected from the anterior [point Ba; POP Questionnaire (POP-Q)] and/or posterior (point Bp; POP-Q) vaginal wall of 15 women who underwent vaginal surgery for POP. Both histological and biomechanical assessments were performed from the same tissue samples in 14 of 15 patients. For histological assessment, the density of collagen and elastin fibers was determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. For biomechanical testing, uniaxial tension tests were performed to evaluate vaginal tissue stiffness at low (C0) and high (C1) deformation rates. Biomechanical testing highlights the hyperelastic behavior of the vaginal wall. At low strains (C0), vaginal tissue appeared stiffer when elastin density was low. We found a statistically significant inverse relationship between C0 and the elastin/collagen ratio (p = 0.048) in the lamina propria. However, at large strain levels (C1), no clear relationship was observed between elastin density or elastin/collagen ratio and stiffness, likely reflecting the large dispersion of the mechanical behavior of the tissue samples. Histological and biomechanical properties of the vaginal wall vary from patient to patient. This study suggests that elastin density deserves consideration as a relevant factor of vaginal stiffness in women with POP.

Cellulose microfibril orientation of Picea abies and its variability at the micron-level determined by Raman imaging

PubMed Central

Gierlinger, Notburga; Luss, Saskia; König, Christian; Konnerth, Johannes; Eder, Michaela; Fratzl, Peter

2010-01-01

The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns. Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle). By changing the laser polarization direction in 3° steps, the dependency between cellulose and laser orientation direction was investigated. Orientation-dependent changes of band height ratios and spectra were described by quadratic linear regression and partial least square regressions, respectively. Using the models and regressions with high coefficients of determination (R2 > 0.99) microfibril orientation was predicted in the S1 and S2 layers distinguished by the Raman imaging approach in cross-sections of spruce normal, opposite, and compression wood. The determined microfibril angle (MFA) in the different S2 layers ranged from 0° to 49.9° and was in coincidence with X-ray diffraction determination. With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues. PMID:20007198

Assessment of Myocardial Remodeling Using an Elastin/Tropoelastin Specific Agent with High Field Magnetic Resonance Imaging (MRI).

PubMed

Protti, Andrea; Lavin, Begoña; Dong, Xuebin; Lorrio, Silvia; Robinson, Simon; Onthank, David; Shah, Ajay M; Botnar, Rene M

2015-08-13

Well-defined inflammation, proliferation, and maturation phases orchestrate the remodeling of the injured myocardium after myocardial infarction (MI) by controlling the formation of new extracellular matrix. The extracellular matrix consists mainly of collagen but also fractions of elastin. It is thought that elastin is responsible for maintaining elastic properties of the myocardium, thus reducing the risk of premature rupture. An elastin/tropoelastin-specific contrast agent (Gd-ESMA) was used to image tropoelastin and mature elastin fibers for in vivo assessment of extracellular matrix remodeling post-MI. Gd-ESMA enhancement was studied in a mouse model of myocardial infarction using a 7 T MRI scanner and results were compared to those achieved after injection of a nonspecific control contrast agent, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). In the infarcted tissue, Gd-ESMA uptake (measured as R1 relaxation rate) steadily increased from day 3 to day 21 as a result of the synthesis of elastin/tropoelastin. R1 values were in good agreement with histological findings. A similar R1 behavior was observed in the remote myocardium. No mature cross-linked elastin was found at any time point. In contrast, Gd-DTPA uptake was only observed in the infarct with no changes in R1 values between 3 and 21 days post-MI. We demonstrate the feasibility of in vivo imaging of extracellular matrix remodeling post-MI using a tropoelastin/elastin binding MR contrast agent, Gd-ESMA. We found that tropoelastin is the main contributor to the increased MRI signal at late stages of MI where its augmentation in areas of infarction was in good agreement with the R1 increase. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Peroxisome proliferator-activated receptor δ modulates MMP-2 secretion and elastin expression in human dermal fibroblasts exposed to ultraviolet B radiation.

PubMed

Ham, Sun Ah; Yoo, Taesik; Hwang, Jung Seok; Kang, Eun Sil; Paek, Kyung Shin; Park, Chankyu; Kim, Jin-Hoi; Do, Jeong Tae; Seo, Han Geuk

2014-10-01

Changes in skin connective tissues mediated by ultraviolet (UV) radiation have been suggested to cause the skin wrinkling normally associated with premature aging of the skin. Recent investigations have shown that peroxisome proliferator-activated receptor (PPAR) δ plays multiple biological roles in skin homeostasis. We attempted to investigate whether PPARδ modulates elastin protein levels and secretion of matrix metalloproteinase (MMP)-2 in UVB-irradiated human dermal fibroblasts (HDFs) and mouse skin. These studies were undertaken in primary HDFs or HR-1 hairless mice using Western blot analyses, small interfering (si)RNA-mediated gene silencing, and Fluorescence microscopy. In HDFs, UVB irradiation induced increased secretion of MMP-2 and reduced levels of elastin. Activation of PPARδ by GW501516, a ligand specific for PPARδ, markedly attenuated UVB-induced MMP-2 secretion with a concomitant increase in the level of elastin. These effects were reduced by the presence of siRNAs against PPARδ or treatment with GSK0660, a specific inhibitor of PPARδ. Furthermore, GW501516 elicited a dose- and time-dependent increase in the expression of elastin. Modulation of MMP-2 secretion and elastin levels by GW501516 was associated with a reduction in reactive oxygen species (ROS) production in HDFs exposed to UVB. Finally, in HR-1 hairless mice, administration of GW501516 significantly reduced UVB-induced MMP-2 expression with a concomitant increase in elastin levels, and these effects were significantly reduced by the presence of GSK0660. Our results suggest that PPARδ-mediated modulation of MMP-2 secretion and elastin expression may contribute to the maintenance of skin integrity by inhibiting ROS generation. Copyright © 2014 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

The action of neutrophil serine proteases on elastin and its precursor.

PubMed

Heinz, Andrea; Jung, Michael C; Jahreis, Günther; Rusciani, Anthony; Duca, Laurent; Debelle, Laurent; Weiss, Anthony S; Neubert, Reinhard H H; Schmelzer, Christian E H

2012-01-01

This study aimed to investigate the degradation of the natural substrates tropoelastin and elastin by the neutrophil-derived serine proteases human leukocyte elastase (HLE), proteinase 3 (PR3) and cathepsin G (CG). Focus was placed on determining their cleavage site specificities using mass spectrometric techniques. Moreover, the release of bioactive peptides from elastin by the three proteases was studied. Tropoelastin was comprehensively degraded by all three proteases, whereas less cleavage occurred in mature cross-linked elastin. An analysis of the cleavage site specificities of the three proteases in tropoelastin and elastin revealed that HLE and PR3 similarly tolerate hydrophobic and/or aliphatic amino acids such as Ala, Gly and Val at P(1), which are also preferred by CG. In addition, CG prefers the bulky hydrophobic amino acid Leu and accepts the bulky aromatic amino acids Phe and Tyr. CG shows a strong preference for the charged amino acid Lys at P(1) in tropoelastin, whereas Lys was not identified at P(1) in CG digests of elastin due to extensive cross-linking at Lys residues in mature elastin. All three serine proteases showed a clear preference for Pro at P(2) and P(4)'. With respect to the liberation of potentially bioactive peptides from elastin, the study revealed that all three serine proteases have a similar ability to release bioactive sequences, with CG producing the highest number of these peptides. In bioactivity studies, potentially bioactive peptides that have not been investigated on their bioactivity to date, were tested. Three new bioactive GxxPG motifs were identified; GVYPG, GFGPG and GVLPG. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

In vivo assessment of aortic aneurysm wall integrity using elastin-specific molecular magnetic resonance imaging.

PubMed

Botnar, René M; Wiethoff, Andrea J; Ebersberger, Ullrich; Lacerda, Sara; Blume, Ulrike; Warley, Alice; Jansen, Christian H P; Onthank, David C; Cesati, Richard R; Razavi, Reza; Marber, Michael S; Hamm, Bernd; Schaeffter, Tobias; Robinson, Simon P; Makowski, Marcus R

2014-07-01

The incidence of abdominal aortic aneurysms (AAAs) has increased during the last decades. However, there is still controversy about the management of medium-sized AAAs. Therefore, novel biomarkers, besides aneurysmal diameter, are needed to assess aortic wall integrity and risk of rupture. Elastin is the key protein for maintaining aortic wall tensile strength and stability. The progressive breakdown of structural proteins, in particular, medial elastin, is responsible for the inability of the aortic wall to withstand intraluminal hemodynamic forces. Here, we evaluate the usefulness of elastin-specific molecular MRI for the in vivo characterization of AAAs. To induce AAAs, ApoE(-/-) mice were infused with angiotensin-II. An elastin-specific magnetic resonance molecular imaging agent (ESMA) was administered after 1, 2, 3, and 4 weeks of angiotensin-II infusion to assess elastin composition of the aorta (n=8 per group). The high signal provided by ESMA allowed for imaging with high spatial resolution, resulting in an accurate assessment of ruptured elastic laminae and the compensatory expression of elastic fibers. In vivo contrast-to-noise ratios and R1-relaxation rates after ESMA administration were in good agreement with ex vivo histomorphometry (Elastica van Gieson stain) and gadolinium concentrations determined by inductively coupled plasma mass spectroscopy. Electron microscopy confirmed colocalization of ESMA with elastic fibers. Changes in elastin content could be readily delineated and quantified at different stages of AAAs by elastin-specific molecular magnetic resonance imaging. ESMA-MRI offers potential for the noninvasive detection of the aortic rupture site prior to dilation of the aorta and the subsequent in vivo monitoring of compensatory repair processes during the progression of AAAs. © 2014 American Heart Association, Inc.

Modeling hygroelastic properties of genetically modified aspen

Treesearch

Laszlo Horvath; Perry Peralta; Ilona Peszlen; Levente Csoka; Balazs Horvath; Joseph Jakes

2012-01-01

Numerical and three-dimensional finite element models were developed to improve understanding of major factors affecting hygroelastic wood properties. Effects of chemical composition, microfibril angle, crystallinity, structure of microfibrils, moisture content, and hydrophilicity of the cell wall were included in the model. Wood from wild-type and decreased-lignin...

Synthesis and Structural Characterization of Reflectin Proteins

DTIC Science & Technology

2012-02-29

constructs of interest included a reflectin 1a domain 3 (D3) monomer, a domain 3 dimer, subdomain peptides, recombinant reflectin 1b, an elastin -reflectin...diblock copolymer, and an elastin -reflectin-GFP fusion protein. After construction of the sequences of interest at the DNA level, protein expression...characterization was performed. The unique spectral properties associated with recombinant reflectin protein materials make elastin -reflectin

Moyamoya disease and artery tortuosity as rare phenotypes in a patient with an elastin mutation.

PubMed

Ishiwata, Tsukasa; Tanabe, Nobuhiro; Shigeta, Ayako; Yokota, Hajime; Tsushima, Kenji; Terada, Jiro; Sakao, Seiichiro; Morisaki, Hiroko; Morisaki, Takayuki; Tatsumi, Koichiro

2016-07-01

Sporadic and familial elastin mutations can occur in large vessel stenosis such as supravalvular aortic stenosis and narrowing of the descending aorta. However, there are very few reports regarding the arteriopathy of cerebral, pulmonary or abdominal arteries in elastin mutations. We herein report the case of a Japanese female patient presenting with multiple arteriopathy including moyamoya disease, a tortuosity of abdominal arteries and pulmonary hypertension due to peripheral pulmonary artery stenosis. This case suggests the possible progression of cerebral arteriopathy including moyamoya disease in patients with elastin mutations. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Mechanistic Insight into the Elastin Degradation Process by the Metalloprotease Myroilysin from the Deep-Sea Bacterium Myroides profundi D25

PubMed Central

Yang, Jie; Zhao, Hui-Lin; Tang, Bai-Lu; Chen, Xiu-Lan; Su, Hai-Nan; Zhang, Xi-Ying; Song, Xiao-Yan; Zhou, Bai-Cheng; Xie, Bin-Bin; Weiss, Anthony S.; Zhang, Yu-Zhong

2015-01-01

Elastases have been widely studied because of their important uses as medicine and meat tenderizers. However, there are relatively few studies on marine elastases. Myroilysin, secreted by Myroides profundi D25 from deep-sea sediment, is a novel elastase. In this study, we examined the elastin degradation mechanism of myroilysin. When mixed with insoluble bovine elastin, myroilysin bound hydrophobically, suggesting that this elastase may interact with the hydrophobic domains of elastin. Consistent with this, analysis of the cleavage pattern of myroilysin on bovine elastin and recombinant tropoelastin revealed that myroilysin preferentially cleaves peptide bonds with hydrophobic residues at the P1 and/or P1′ positions. Scanning electron microscopy (SEM) of cross-linked recombinant tropoelastin degraded by myroilysin showed preferential damages of spherules over cross-links, as expected for a hydrophobic preference. The degradation process of myroilysin on bovine elastin fibres was followed by light microscopy and SEM, revealing that degradation begins with the formation of crevices and cavities at the fibre surface, with these openings increasing in number and size until the fibre breaks into small pieces, which are subsequently fragmented. Our results are helpful for developing biotechnological applications for myroilysin. PMID:25793427

Evaluation of a biomimetic 3D substrate based on the Human Elastin-like Polypeptides (HELPs) model system for elastolytic activity detection.

PubMed

Corich, Lucia; Busetti, Marina; Petix, Vincenzo; Passamonti, Sabina; Bandiera, Antonella

2017-08-10

Elastin is a fibrous protein that confers elasticity to tissues such as skin, arteries and lung. It is extensively cross-linked, highly hydrophobic and insoluble. Nevertheless, elastin can be hydrolysed by bacterial proteases in infectious diseases, resulting in more or less severe tissue damage. Thus, development of substrates able to reliably and specifically detect pathogen-secreted elastolytic activity is needed to improve the in vitro evaluation of the injury that bacterial proteases may provoke. In this work, two human biomimetic elastin polypeptides, HELP and HELP1, as well as the matrices derived from HELP, have been probed as substrates for elastolytic activity detection. Thirty strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients were analyzed in parallel with standard substrates, to detect proteolytic and elastolytic activity. Results point to the HELP-based 3D matrix as an interesting biomimetic model of elastin to assess bacterial elastolytic activity in vitro. Moreover, this model substrate enables to further elucidate the mechanism underlying elastin degradation at molecular level, as well as to develop biomimetic material-based devices responsive to external stimuli. Copyright © 2017 Elsevier B.V. All rights reserved.

Recombinant DNA technology and click chemistry: a powerful combination for generating a hybrid elastin-like-statherin hydrogel to control calcium phosphate mineralization

PubMed Central

Misbah, Mohamed Hamed; Santos, Mercedes; Quintanilla, Luis; Günter, Christina; Alonso, Matilde; Taubert, Andreas

2017-01-01

Understanding the mechanisms responsible for generating different phases and morphologies of calcium phosphate by elastin-like recombinamers is supreme for bioengineering of advanced multifunctional materials. The generation of such multifunctional hybrid materials depends on the properties of their counterparts and the way in which they are assembled. The success of this assembly depends on the different approaches used, such as recombinant DNA technology and click chemistry. In the present work, an elastin-like recombinamer bearing lysine amino acids distributed along the recombinamer chain has been cross-linked via Huisgen [2 + 3] cycloaddition. The recombinamer contains the SNA15 peptide domains inspired by salivary statherin, a peptide epitope known to specifically bind to and nucleate calcium phosphate. The benefit of using click chemistry is that the hybrid elastin-like-statherin recombinamers cross-link without losing their fibrillar structure. Mineralization of the resulting hybrid elastin-like-statherin recombinamer hydrogels with calcium phosphate is described. Thus, two different hydroxyapatite morphologies (cauliflower- and plate-like) have been formed. Overall, this study shows that crosslinking elastin-like recombinamers leads to interesting matrix materials for the generation of calcium phosphate composites with potential applications as biomaterials. PMID:28487820

The effect of glycation on arterial microstructure and mechanical response.

PubMed

Stephen, Elizabeth A; Venkatasubramaniam, Arundhathi; Good, Theresa A; Topoleski, L D T

2014-08-01

Like engineered materials, an artery's biomechanical behavior and function depend on its microstructure. Glycation is associated with both normal aging and diabetes and has been shown to increase arterial stiffness. In this study we examined the direct effect of glycation on the mechanical response of intact arteries and on the mechanical response and structure of elastin isolated from the arteries. Samples of intact arteries and isolated elastin were prepared from porcine aortas and glycated. The mechanical response of all samples was completed using a uniaxial material test system. Glycation levels were measured using ELISA. A confocal microscope was used to image differences in the structure of the glycated and untreated elastin fibers. We found that, under the conditions used in this study, glycation led to decreased stiffness of elastin isolated from arteries, which was associated with a thinning of elastin fibers as imaged by confocal microscopy. We observed no effect of glycation on collagen fibers under our treatment conditions. These results suggest that glycation leads to weakening of the elastin component of arteries that could contribute to vascular defects seen in diabetes and aging. Prevention of glycation reactions may be an important consideration for vascular health later in life. © 2013 Wiley Periodicals, Inc.

Smooth Muscle-Mediated Connective Tissue Remodeling in Pulmonary Hypertension

NASA Astrophysics Data System (ADS)

Mecham, Robert P.; Whitehouse, Loren A.; Wrenn, David S.; Parks, William C.; Griffin, Gail L.; Senior, Robert M.; Crouch, Edmond C.; Stenmark, Kurt R.; Voelkel, Norbert F.

1987-07-01

Abnormal accumulation of connective tissue in blood vessels contributes to alterations in vascular physiology associated with disease states such as hypertension and atherosclerosis. Elastin synthesis was studied in blood vessels from newborn calves with severe pulmonary hypertension induced by alveolar hypoxia in order to investigate the cellular stimuli that elicit changes in pulmonary arterial connective tissue production. A two- to fourfold increase in elastin production was observed in pulmonary artery tissue and medial smooth muscle cells from hypertensive calves. This stimulation of elastin production was accompanied by a corresponding increase in elastin messenger RNA consistent with regulation at the transcriptional level. Conditioned serum harvested from cultures of pulmonary artery smooth muscle cells isolated from hypertensive animals contained one or more low molecular weight elastogenic factors that stimulated the production of elastin in both fibroblasts and smooth muscle cells and altered the chemotactic responsiveness of fibroblasts to elastin peptides. These results suggest that connective tissue changes in the pulmonary vasculature in response to pulmonary hypertension are orchestrated by the medial smooth muscle cell through the generation of specific differentiation factors that alter both the secretory phenotype and responsive properties of surrounding cells.

Age estimation based on aspartic acid racemization in elastin from the yellow ligaments.

PubMed

Ritz-Timme, S; Laumeier, I; Collins, M

2003-04-01

The yellow ligaments of the spine are characterized by an exceptionally high content of elastin, a protein with a proved longevity in several human tissues. This unique biochemical composition suggested a suitability of yellow ligaments for age estimation based on aspartic acid racemization (AAR), which was tested by determination of AAR in total tissue specimens and in purified elastin from yellow ligaments of individuals of known age. AAR was found to increase with age in both sample sets. The purified elastin samples exhibited a much faster kinetics than the total tissue, with ca. 3.7-4.6-fold higher apparent rates. The relationship between AAR and age was much closer in the purified elastin samples ( r=0.96-0.99) and it can therefore be used as a basis for biochemical age estimation. The analysis of total tissue samples cannot be recommended since the AAR values can be strongly influenced even by slight, histologically non-detectable variations in the collagen content. Age estimation based on AAR in purified elastin from yellow ligaments may be a valuable additional tool in the identification of unidentified cadavers, especially in cases where other methods cannot be applied (e.g. no available teeth, body parts).

Elastin-PLGA hybrid electrospun nanofiber scaffolds for salivary epithelial cell self-organization and polarization.

PubMed

Foraida, Zahraa I; Kamaldinov, Tim; Nelson, Deirdre A; Larsen, Melinda; Castracane, James

2017-10-15

Development of electrospun nanofibers that mimic the structural, mechanical and biochemical properties of natural extracellular matrices (ECMs) is a promising approach for tissue regeneration. Electrospun fibers of synthetic polymers partially mimic the topography of the ECM, however, their high stiffness, poor hydrophilicity and lack of in vivo-like biochemical cues is not optimal for epithelial cell self-organization and function. In search of a biomimetic scaffold for salivary gland tissue regeneration, we investigated the potential of elastin, an ECM protein, to generate elastin hybrid nanofibers that have favorable physical and biochemical properties for regeneration of the salivary glands. Elastin was introduced to our previously developed poly-lactic-co-glycolic acid (PLGA) nanofiber scaffolds by two methods, blend electrospinning (EP-blend) and covalent conjugation (EP-covalent). Both methods for elastin incorporation into the nanofibers improved the wettability of the scaffolds while only blend electrospinning of elastin-PLGA nanofibers and not surface conjugation of elastin to PLGA fibers, conferred increased elasticity to the nanofibers measured by Young's modulus. After two days, only the blend electrospun nanofiber scaffolds facilitated epithelial cell self-organization into cell clusters, assessed with nuclear area and nearest neighbor distance measurements, leading to the apicobasal polarization of salivary gland epithelial cells after six days, which is vital for cell function. This study suggests that elastin electrospun nanofiber scaffolds have potential application in regenerative therapies for salivary glands and other epithelial organs. Regenerating the salivary glands by mimicking the extracellular matrix (ECM) is a promising approach for long term treatment of salivary gland damage. Despite their topographic similarity to the ECM, electrospun fibers of synthetic polymers lack the biochemical complexity, elasticity and hydrophilicity of the ECM. Elastin is an ECM protein abundant in the salivary glands and responsible for tissue elasticity. Although it's widely used for tissue regeneration of other organs, little is known about its utility in regenerating the salivary tissue. This study describes the use of elastin to improve the elasticity, hydrophilicity and biochemical complexity of synthetic nanofibers and its potential in directing in vivo-like organization of epithelial salivary cells which helps the design of efficient salivary gland regeneration scaffolds. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fingerprinting Desmosine-Containing Elastin Peptides

NASA Astrophysics Data System (ADS)

Schräder, Christoph U.; Heinz, Andrea; Majovsky, Petra; Schmelzer, Christian E. H.

2015-05-01

Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS2 data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.

Fingerprinting desmosine-containing elastin peptides.

PubMed

Schräder, Christoph U; Heinz, Andrea; Majovsky, Petra; Schmelzer, Christian E H

2015-05-01

Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS(2) data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.

Development of short and highly potent self-assembling elastin-derived pentapeptide repeats containing aromatic amino acid residues.

PubMed

Taniguchi, Suguru; Watanabe, Noriko; Nose, Takeru; Maeda, Iori

2016-01-01

Tropoelastin is the primary component of elastin, which forms the elastic fibers that make up connective tissues. The hydrophobic domains of tropoelastin are thought to mediate the self-assembly of elastin into fibers, and the temperature-mediated self-assembly (coacervation) of one such repetitive peptide sequence (VPGVG) has been utilized in various bio-applications. To elucidate a mechanism for coacervation activity enhancement and to develop more potent coacervatable elastin-derived peptides, we synthesized two series of peptide analogs containing an aromatic amino acid, Trp or Tyr, in addition to Phe-containing analogs and tested their functional characteristics. Thus, position 1 of the hydrophobic pentapeptide repeat of elastin (X(1)P(2)G(3)V(4)G(5)) was substituted by Trp or Tyr. Eventually, we acquired a novel, short Trp-containing elastin-derived peptide analog (WPGVG)3 with potent coacervation ability. From the results obtained during this process, we determined the importance of aromaticity and hydrophobicity for the coacervation potency of elastin-derived peptide analogs. Generally, however, the production of long-chain synthetic polypeptides in quantities sufficient for commercial use remain cost-prohibitive. Therefore, the identification of (WPGVG)3, which is a 15-mer short peptide consisting simply of five natural amino acids and shows temperature-dependent self-assembly activity, might serve as a foundation for the development of various kinds of biomaterials. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

The changes in crosslink contents in tissues after formalin fixation.

PubMed

Abe, Masashi; Takahashi, Masaaki; Horiuchi, Kentaro; Nagano, Akira

2003-07-01

The aim of this study was to detect crosslinks of collagen and elastin in formalin-fixed tissue, to perform quantification of these crosslinks, and to investigate the effects of formalin fixation on crosslink contents in human yellow ligament and cartilage. Pyridinoline (Pyr) is a stable and nonreducible crosslink of collagen. Pentosidine (Pen) is a senescent crosslink formed between arginine and lysine in matrix proteins, including collagen. Desmosine (Des) and its isomer isodesmosine (Isodes) are crosslinks specifically found in elastin. It is useful to measure crosslink contents of collagen and elastin as a way of investigating the properties of various tissues or their pathological changes. If it is possible to evaluate crosslinks of collagen and elastin in formalin-fixed tissues, we can investigate crosslinks in a wide variety of tissues. We used HPLC to compare the concentrations of Pyr, Pen, Des, and Isodes in the formalin-fixed tissues with their concentrations in the frozen tissues. Pyr and Pen were detected in both the formalin-fixed yellow ligament and the cartilage, and their concentrations were not significantly affected by or related to the duration of formalin fixation. Des and Isodes were detected in the formalin-fixed yellow ligament but in significantly lower amounts compared to the frozen samples. We concluded that crosslinks of collagen were preserved in formalin, but crosslinks of elastin were not preserved in it. The reason for this might be that formalin did not fix elastin tissues sufficiently or it destroyed, masked, or altered elastin crosslinks.

Chronic antihypertensive treatment improves pulse pressure but not large artery mechanics in a mouse model of congenital vascular stiffness

PubMed Central

Halabi, Carmen M.; Broekelmann, Thomas J.; Knutsen, Russell H.; Ye, Li; Mecham, Robert P.

2015-01-01

Increased arterial stiffness is a common characteristic of humans with Williams-Beuren syndrome and mouse models of elastin insufficiency. Arterial stiffness is associated with multiple negative cardiovascular outcomes, including myocardial infarction, stroke, and sudden death. Therefore, identifying therapeutic interventions that improve arterial stiffness in response to changes in elastin levels is of vital importance. The goal of this study was to determine the effect of chronic pharmacologic therapy with different classes of antihypertensive medications on arterial stiffness in elastin insufficiency. Elastin-insufficient mice 4–6 wk of age and wild-type littermates were subcutaneously implanted with osmotic micropumps delivering a continuous dose of one of the following: vehicle, losartan, nicardipine, or propranolol for 8 wk. At the end of treatment period, arterial blood pressure and large artery compliance and remodeling were assessed. Our results show that losartan and nicardipine treatment lowered blood pressure and pulse pressure in elastin-insufficient mice. Elastin and collagen content of abdominal aortas as well as ascending aorta and carotid artery biomechanics were not affected by any of the drug treatments in either genotype. By reducing pulse pressure and shifting the working pressure range of an artery to a more compliant region of the pressure-diameter curve, antihypertensive medications may mitigate the consequences of arterial stiffness, an effect that is drug class independent. These data emphasize the importance of early recognition and long-term management of hypertension in Williams-Beuren syndrome and elastin insufficiency. PMID:26232234

A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/Nylon-6 blends.

PubMed

Liu, Hongzhi; Yao, Fei; Xu, Yanjun; Wu, Qinglin

2010-05-01

A novel wood flour (WF)-filled composite based on the microfibrillar high-density polyethylene (HDPE) and Nylon-6 co-blend, in which both in situ formed Nylon-6 microfibrils and WF acted as reinforcing elements, was successfully developed using a two-step extrusion method. At the 30wt.% WF loading level, WF-filled composite based on the microfibrillized HDPE/Nylon-6 blend exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of WF reduced short-term creep response of HDPE matrix and the presence of Nylon-6 microfibrils further contributed to the creep reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

Structure of the Fibrillin-1 N-Terminal Domains Suggests that Heparan Sulfate Regulates the Early Stages of Microfibril Assembly

PubMed Central

Yadin, David A.; Robertson, Ian B.; McNaught-Davis, Joanne; Evans, Paul; Stoddart, David; Handford, Penny A.; Jensen, Sacha A.; Redfield, Christina

2013-01-01

Summary The human extracellular matrix glycoprotein fibrillin-1 is the primary component of the 10- to 12-nm-diameter microfibrils, which perform key structural and regulatory roles in connective tissues. Relatively little is known about the molecular mechanisms of fibrillin assembly into microfibrils. Studies using recombinant fibrillin fragments indicate that an interaction between the N- and C-terminal regions drives head-to-tail assembly. Here, we present the structure of a fibrillin N-terminal fragment comprising the fibrillin unique N-terminal (FUN) and the first three epidermal growth factor (EGF)-like domains (FUN-EGF3). Two rod-like domain pairs are separated by a short, flexible linker between the EGF1 and EGF2 domains. We also show that the binding site for the C-terminal region spans multiple domains and overlaps with a heparin interaction site. These data suggest that heparan sulfate may sequester fibrillin at the cell surface via FUN-EGF3 prior to aggregation of the C terminus, thereby regulating microfibril assembly. PMID:24035709

Wide-Angle X-Ray Scattering and Solid-State Nuclear Magnetic Resonance Data Combined to Test Models for Cellulose Microfibrils in Mung Bean Cell Walls1

PubMed Central

Newman, Roger H.; Hill, Stefan J.; Harris, Philip J.

2013-01-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette. PMID:24154621

Cellulose Microfibril Formation by Surface-Tethered Cellulose Synthase Enzymes.

PubMed

Basu, Snehasish; Omadjela, Okako; Gaddes, David; Tadigadapa, Srinivas; Zimmer, Jochen; Catchmark, Jeffrey M

2016-02-23

Cellulose microfibrils are pseudocrystalline arrays of cellulose chains that are synthesized by cellulose synthases. The enzymes are organized into large membrane-embedded complexes in which each enzyme likely synthesizes and secretes a β-(1→4) glucan. The relationship between the organization of the enzymes in these complexes and cellulose crystallization has not been explored. To better understand this relationship, we used atomic force microscopy to visualize cellulose microfibril formation from nickel-film-immobilized bacterial cellulose synthase enzymes (BcsA-Bs), which in standard solution only form amorphous cellulose from monomeric BcsA-B complexes. Fourier transform infrared spectroscopy and X-ray diffraction techniques show that surface-tethered BcsA-Bs synthesize highly crystalline cellulose II in the presence of UDP-Glc, the allosteric activator cyclic-di-GMP, as well as magnesium. The cellulose II cross section/diameter and the crystal size and crystallinity depend on the surface density of tethered enzymes as well as the overall concentration of substrates. Our results provide the correlation between cellulose microfibril formation and the spatial organization of cellulose synthases.

Bioreactor-induced mesenchymal progenitor cell differentiation and elastic fiber assembly in engineered vascular tissues.

PubMed

Lin, Shigang; Mequanint, Kibret

2017-09-01

In vitro maturation of engineered vascular tissues (EVT) requires the appropriate incorporation of smooth muscle cells (SMC) and extracellular matrix (ECM) components similar to native arteries. To this end, the aim of the current study was to fabricate 4mm inner diameter vascular tissues using mesenchymal progenitor cells seeded into tubular scaffolds. A dual-pump bioreactor operating either in perfusion or pulsatile perfusion mode was used to generate physiological-like stimuli to promote progenitor cell differentiation, extracellular elastin production, and tissue maturation. Our data demonstrated that pulsatile forces and perfusion of 3D tubular constructs from both the lumenal and ablumenal sides with culture media significantly improved tissue assembly, effectively inducing mesenchymal progenitor cell differentiation to SMCs with contemporaneous elastin production. With bioreactor cultivation, progenitor cells differentiated toward smooth muscle lineage characterized by the expression of smooth muscle (SM)-specific markers smooth muscle alpha actin (SM-α-actin) and smooth muscle myosin heavy chain (SM-MHC). More importantly, pulsatile perfusion bioreactor cultivation enhanced the synthesis of tropoelastin and its extracellular cross-linking into elastic fiber compared with static culture controls. Taken together, the current study demonstrated progenitor cell differentiation and vascular tissue assembly, and provides insights into elastin synthesis and assembly to fibers. Incorporation of elastin into engineered vascular tissues represents a critical design goal for both mechanical and biological functions. In the present study, we seeded porous tubular scaffolds with multipotent mesenchymal progenitor cells and cultured in dual-pump pulsatile perfusion bioreactor. Physiological-like stimuli generated by bioreactor not only induced mesenchymal progenitor cell differentiation to vascular smooth muscle lineage but also actively promoted elastin synthesis and fiber assembly. Gene expression and protein synthesis analyses coupled with histological and immunofluorescence staining revealed that elastin-containing vascular tissues were fabricated. More importantly, co-localization and co-immunoprecipitation experiments demonstrated that elastin and fibrillin-1 were abundant throughout the cross-section of the tissue constructs suggesting a process of elastin protein crosslinking. This study paves a way forward to engineer elastin-containing functional vascular substitutes from multipotent progenitor cells in a bioreactor. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The supramolecular structure of bone: X-ray scattering analysis and lateral structure modeling

PubMed Central

Zhou, Hong-Wen; Burger, Christian; Wang, Hao; Hsiao, Benjamin S.; Chu, Benjamin; Graham, Lila

2016-01-01

The evolution of vertebrates required a key development in supramolecular evolution: internally mineralized collagen fibrils. In bone, collagen molecules and mineral crystals form a nanocomposite material comparable to cast iron in tensile strength, but several times lighter and more flexible. Current understanding of the internal nanoscale structure of collagen fibrils, derived from studies of rat tail tendon (RTT), does not explain how nucleation and growth of mineral crystals can occur inside a collagen fibril. Experimental obstacles encountered in studying bone have prevented a solution to this problem for several decades. This report presents a lateral packing model for collagen molecules in bone fibrils, based on the unprecedented observation of multiple resolved equatorial reflections for bone tissue using synchrotron small-angle X-ray scattering (SAXS; ∼1 nm resolution). The deduced structure for pre-mineralized bone fibrils includes features that are not present in RTT: spatially discrete microfibrils. The data are consistent with bone microfibrils similar to pentagonal Smith microfibrils, but are not consistent with the (nondiscrete) quasi-hexagonal microfibrils reported for RTT. These results indicate that collagen fibrils in bone and tendon differ in their internal structure in a manner that allows bone fibrils, but not tendon fibrils, to internally mineralize. In addition, the unique pattern of collagen cross-link types and quantities in mineralized tissues can be can be accounted for, in structural/functional terms, based on a discrete microfibril model. PMID:27599731

Functional Specialization of Cellulose Synthase Isoforms in a Moss Shows Parallels with Seed Plants1[OPEN

PubMed Central

Li, Xingxing; Huang, Shixin; Van de Meene, Allison M.L.; Tran, Mai L.; Killeavy, Erin; Mercure, Danielle; Burton, Rachel A.

2017-01-01

The secondary cell walls of tracheary elements and fibers are rich in cellulose microfibrils that are helically oriented and laterally aggregated. Support cells within the leaf midribs of mosses deposit cellulose-rich secondary cell walls, but their biosynthesis and microfibril organization have not been examined. Although the Cellulose Synthase (CESA) gene families of mosses and seed plants diversified independently, CESA knockout analysis in the moss Physcomitrella patens revealed parallels with Arabidopsis (Arabidopsis thaliana) in CESA functional specialization, with roles for both subfunctionalization and neofunctionalization. The similarities include regulatory uncoupling of the CESAs that synthesize primary and secondary cell walls, a requirement for two or more functionally distinct CESA isoforms for secondary cell wall synthesis, interchangeability of some primary and secondary CESAs, and some CESA redundancy. The cellulose-deficient midribs of ppcesa3/8 knockouts provided negative controls for the structural characterization of stereid secondary cell walls in wild type P. patens. Sum frequency generation spectra collected from midribs were consistent with cellulose microfibril aggregation, and polarization microscopy revealed helical microfibril orientation only in wild type leaves. Thus, stereid secondary walls are structurally distinct from primary cell walls, and they share structural characteristics with the secondary walls of tracheary elements and fibers. We propose a mechanism for the convergent evolution of secondary walls in which the deposition of aggregated and helically oriented microfibrils is coupled to rapid and highly localized cellulose synthesis enabled by regulatory uncoupling from primary wall synthesis. PMID:28768816

Transcriptome profiling of Pinus radiata juvenile wood with contrasting stiffness identifies putative candidate genes involved in microfibril orientation and cell wall mechanics

PubMed Central

2011-01-01

Background The mechanical properties of wood are largely determined by the orientation of cellulose microfibrils in secondary cell walls. Several genes and their allelic variants have previously been found to affect microfibril angle (MFA) and wood stiffness; however, the molecular mechanisms controlling microfibril orientation and mechanical strength are largely uncharacterised. In the present study, cDNA microarrays were used to compare gene expression in developing xylem with contrasting stiffness and MFA in juvenile Pinus radiata trees in order to gain further insights into the molecular mechanisms underlying microfibril orientation and cell wall mechanics. Results Juvenile radiata pine trees with higher stiffness (HS) had lower MFA in the earlywood and latewood of each ring compared to low stiffness (LS) trees. Approximately 3.4 to 14.5% out of 3, 320 xylem unigenes on cDNA microarrays were differentially regulated in juvenile wood with contrasting stiffness and MFA. Greater variation in MFA and stiffness was observed in earlywood compared to latewood, suggesting earlywood contributes most to differences in stiffness; however, 3-4 times more genes were differentially regulated in latewood than in earlywood. A total of 108 xylem unigenes were differentially regulated in juvenile wood with HS and LS in at least two seasons, including 43 unigenes with unknown functions. Many genes involved in cytoskeleton development and secondary wall formation (cellulose and lignin biosynthesis) were preferentially transcribed in wood with HS and low MFA. In contrast, several genes involved in cell division and primary wall synthesis were more abundantly transcribed in LS wood with high MFA. Conclusions Microarray expression profiles in Pinus radiata juvenile wood with contrasting stiffness has shed more light on the transcriptional control of microfibril orientation and the mechanical properties of wood. The identified candidate genes provide an invaluable resource for further gene function and association genetics studies aimed at deepening our understanding of cell wall biomechanics with a view to improving the mechanical properties of wood. PMID:21962175

Mechanical, structural, and dynamical modifications of cholesterol exposed porcine aortic elastin.

PubMed

Bilici, Kubra; Morgan, Steven W; Silverstein, Moshe C; Wang, Yunjie; Sun, Hyung Jin; Zhang, Yanhang; Boutis, Gregory S

2016-11-01

Elastin is a protein of the extracellular matrix that contributes significantly to the elasticity of connective tissues. In this study, we examine dynamical and structural modifications of aortic elastin exposed to cholesterol by NMR spectroscopic and relaxation methodologies. Macroscopic measurements are also presented and reveal that cholesterol treatment may cause a decrease in the stiffness of tissue. 2 H NMR relaxation techniques revealed differences between the relative populations of water that correlate with the swelling of the tissue following cholesterol exposure. 13 C magic-angle-spinning NMR spectroscopy and relaxation methods indicate that cholesterol treated aortic elastin is more mobile than control samples. Molecular dynamics simulations on a short elastin repeat VPGVG in the presence of cholesterol are used to investigate the energetic and entropic contributions to the retractive force, in comparison to the same peptide in water. Peptide stiffness is observed to reduce following cholesterol exposure due to a decrease in the entropic force. Copyright © 2016 Elsevier B.V. All rights reserved.

A cytokine axis regulates elastin formation and degradation

PubMed Central

Sproul, Erin P.; Argraves, W. Scott

2013-01-01

Underlying the dynamic regulation of tropoelastin expression and elastin formation in development and disease are transcriptional and post-transcriptional mechanisms that have been the focus of much research. Of particular importance is the cytokine–governed elastin regulatory axis in which the pro-elastogenic activities of transforming growth factor β-1 (TGFβ1) and insulin-like growth factor-I (IGF-I) are opposed by anti-elastogenic activities of basic fibroblast growth factor (bFGF/FGF-2), heparin-binding epidermal growth factor-like growth factor (HB-EGF), EGF, PDGF-BB, TGFα, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and noncanonical TGFβ1 signaling. A key mechanistic feature of the regulatory axis is that cytokines influence elastin formation through effects on the cell cycle involving control of cyclin–cyclin dependent kinase complexes and activation of the Ras/MEK/ERK signaling pathway. In this article we provide an overview of the major cytokines/growth factors that modulate elastogenesis and describe the underlying molecular mechanisms for their action on elastin production. PMID:23160093

Small leucine-rich repeat proteoglycans associated with mature insoluble elastin serve as binding sites for galectins.

PubMed

Itoh, Aiko; Nonaka, Yasuhiro; Ogawa, Takashi; Nakamura, Takanori; Nishi, Nozomu

2017-11-01

We previously reported that galectin-9 (Gal-9), an immunomodulatory animal lectin, could bind to insoluble collagen preparations and exerted direct cytocidal effects on immune cells. In the present study, we found that mature insoluble elastin is capable of binding Gal-9 and other members of the human galectin family. Lectin blot analysis of a series of commercial water-soluble elastin preparations, PES-(A) ~ PES-(E), revealed that only PES-(E) contained substances recognized by Gal-9. Gal-9-interacting substances in PES-(E) were affinity-purified, digested with trypsin and then analyzed by reversed-phase HPLC. Peptide fragments derived from five members of the small leucine-rich repeat proteoglycan family, versican, lumican, osteoglycin/mimecan, prolargin, and fibromodulin, were identified by N-terminal amino acid sequence analysis. The results indicate that Gal-9 and possibly other galectins recognize glycans attached to small leucine-rich repeat proteoglycans associated with insoluble elastin and also indicate the possibility that mature insoluble elastin serves as an extracellular reservoir for galectins.

Mechanical, Structural, and Dynamical Modifications of Cholesterol Exposed Porcine Aortic Elastin

PubMed Central

Bilici, Kubra; Morgan, Steven W.; Silverstein, Moshe C.; Wang, Yunjie; Sun, Hyung Jin; Zhang, Katherine; Boutis, Gregory S.

2016-01-01

Elastin is a protein of the extracellular matrix that contributes significantly to the elasticity of connective tissues. In this study, we examine dynamical and structural modifications of aortic elastin exposed to cholesterol by NMR spectroscopic and relaxation methodologies. Macroscopic measurements are also presented and reveal that cholesterol treatment may cause a decrease in the stiffness of tissue. 2H NMR relaxation techniques revealed differences between the relative populations of water that correlate with the swelling of the tissue following cholesterol exposure. 13C magic-angle-spinning NMR spectroscopy and relaxation methods indicate that cholesterol treated aortic elastin appears more mobile than control samples. Molecular dynamics simulations on a short elastin repeat VPGVG in the presence of cholesterol are used to investigate the energetic and entropic contributions to the retractive force, in comparison to the same peptide in water. Peptide stiffness is observed to reduce following cholesterol exposure due to a decrease in the entropic force. PMID:27648754

Thermo-responsive human α-elastin self-assembled nanoparticles for protein delivery.

PubMed

Kim, Jae Dong; Jung, Youn Jae; Woo, Chang Hee; Choi, Young Chan; Choi, Ji Suk; Cho, Yong Woo

2017-01-01

Self-assembled nanoparticles based on PEGylated human α-elastin were prepared as a potential vehicle for sustained protein delivery. The α-elastin was extracted from human adipose tissue and modified with methoxypolyethyleneglycol (mPEG) to control particle size and enhance the colloidal stability. The PEGylated human α-elastin showed sol-to-particle transition with a lower critical solution temperature (LCST) of 25°C-40°C in aqueous media. The PEGylated human α-elastin nanoparticles (PhENPs) showed a narrow size distribution with an average diameter of 330±33nm and were able to encapsulate significant amounts of insulin and bovine serum albumin (BSA) upon simple mixing at low temperature in water and subsequent heating to physiological temperature. The release profiles of insulin and BSA showed sustained release for 72h. Overall, the thermo-responsive self-assembled PhENPs provide a useful tool for a range of protein delivery and tissue engineering applications. Copyright © 2016 Elsevier B.V. All rights reserved.

The coupled bio-chemo-electro-mechanical behavior of glucose exposed arterial elastin

NASA Astrophysics Data System (ADS)

Zhang, Yanhang; Li, Jiangyu; Boutis, Gregory S.

2017-04-01

Elastin, the principle protein component of the elastic fiber, is a critical extracellular matrix (ECM) component of the arterial wall providing structural resilience and biological signaling essential in vascular morphogenesis and maintenance of mechanical homeostasis. Pathogenesis of many cardiovascular diseases have been associated with alterations of elastin. As a long-lived ECM protein that is deposited and organized before adulthood, elastic fibers can suffer from cumulative effects of biochemical exposure encountered during aging and/or disease, which greatly compromise their mechanical function. This review article covers findings from recent studies of the mechanical and structural contribution of elastin to vascular function, and the effects of biochemical degradation. Results from diverse experimental methods including tissue-level mechanical characterization, fiber-level nonlinear optical imaging, piezoelectric force microscopy, and nuclear magnetic resonance are reviewed. The intriguing coupled bio-chemo-electro-mechanical behavior of elastin calls for a multi-scale and multi-physical understanding of ECM mechanics and mechanobiology in vascular remodeling.

Ultrasonic delineation of aortic microstructure: The relative contribution of elastin and collagen to aortic elasticity

NASA Astrophysics Data System (ADS)

Marsh, Jon N.; Takiuchi, Shin; Lin, Shiow Jiuan; Lanza, Gregory M.; Wickline, Samuel A.

2004-05-01

Aortic elasticity is an important factor in hemodynamic health, and compromised aortic compliance affects not only arterial dynamics but also myocardial function. A variety of pathologic processes (e.g., diabetes, Marfan's syndrome, hypertension) can affect aortic elasticity by altering the microstructure and composition of the elastin and collagen fiber networks within the tunica media. Ultrasound tissue characterization techniques can be used to obtain direct measurements of the stiffness coefficients of aorta by measurement of the speed of sound in specific directions. In this study we sought to define the contributions of elastin and collagen to the mechanical properties of aortic media by measuring the magnitude and directional dependence of the speed of sound before and after selective isolation of either the collagen or elastin fiber matrix. Formalin-fixed porcine aortas were sectioned for insonification in the circumferential, longitudinal, or radial direction and examined using high-frequency (50 MHz) ultrasound microscopy. Isolation of the collagen or elastin fiber matrices was accomplished through treatment with NaOH or formic acid, respectively. The results suggest that elastin is the primary contributor to aortic medial stiffness in the unloaded state, and that there is relatively little anisotropy in the speed of sound or stiffness in the aortic wall.

Aspartic acid racemisation in purified elastin from arteries as basis for age estimation.

PubMed

Dobberstein, R C; Tung, S-M; Ritz-Timme, S

2010-07-01

Aspartic acid racemisation (AAR) results in an age-dependent accumulation of D: -aspartic acid in durable human proteins and can be used as a basis for age estimation. Routinely, age estimation based on AAR is performed by analysis of dentine. However, in forensic practise, teeth are not always available. Non-dental tissues for age estimation may be suitable for age estimation based on AAR if they contain durable proteins that can be purified and analysed. Elastin is such a durable protein. To clarify if purified elastin from arteries is a suitable sample for biochemical age estimation, AAR was determined in purified elastin from arteries from individuals of known age (n = 68 individuals, including n = 15 putrefied corpses), considering the influence of different stages of atherosclerosis and putrefaction on the AAR values. AAR was found to increase with age. The relationship between AAR and age was good enough to serve as basis for age estimation, but worse than known from dentinal proteins. Intravital and post-mortem degradation of elastin may have a moderate effect on the AAR values. Age estimation based on AAR in purified elastin from arteries may be a valuable additional tool in the identification of unidentified cadavers, especially in cases where other methods cannot be applied (e.g., no available teeth and body parts).

Prophylactic effects of elastin peptide derived from the bulbus arteriosus of fish on vascular dysfunction in spontaneously hypertensive rats.

PubMed

Takemori, Kumiko; Yamamoto, Ei; Ito, Hiroyuki; Kometani, Takashi

2015-01-01

To determine the prophylactic effects of an elastin peptide derived from the bulbus arteriosus of bonitos and prolylglycine (PG), a degradation product of elastin peptide, on vascular dysfunction in spontaneously hypertensive rats (SHRs). Male 15-week-old SHR/Izm rats were fed without (control group) or with elastin peptide (1 g/kg body weight) for 5 weeks (EP group), or were infused via an osmotic mini-pump for 4 weeks with PG (PG group) or saline (control group). Using thoracic aortas, we assessed endothelial changes by scanning electron microscopy. Vascular reactivity (contraction and relaxation) and pressure-induced distension was compared. mRNA production levels of endothelial nitric oxide synthase (eNOS) and intercellular adhesion molecule-1 (ICAM-1) were investigated by real-time-polymerase chain reaction. Aortas of the EP group displayed limited endothelial damage compared with that in the control group. Under treatment of SHRs with elastin peptide, the effect of phenylephrine returned closer to the normal level observed in normotensive Wistar-Kyoto (WKY/Izm) rats. mRNA production of eNOS (but not ICAM-1) was greater in the EP group than in the control group. Endothelial damage was suppressed and pressure-induced vascular distension was greater in the PG group than in the corresponding control group. These results suggest that elastin peptide from bonitos elicits prophylactic affects hypertension-associated vascular dysfunction by targeting the eNOS signaling pathway. PG may be a key mediator of the beneficial effects of elastin peptide. Copyright © 2014 Elsevier Inc. All rights reserved.

Design of an elastin-layered dermal regeneration template.

PubMed

Mithieux, Suzanne M; Weiss, Anthony S

2017-04-01

We demonstrate a novel approach for the production of tunable quantities of elastic fibers. We also show that exogenous tropoelastin is rate-limiting for elastin synthesis regardless of the age of the dermal fibroblast donor. Additionally, we provide a strategy to further enhance synthesis by older cells through the application of conditioned media. We show that this approach delivers an elastin layer on one side of the leading dermal repair template for contact with the deep dermis in order to deliver prefabricated elastic fibers to a physiologically appropriate site during subsequent surgery. This system is attractive because it provides for the first time a viable path for sufficient, histologically detectable levels of patient elastin into full-thickness wound sites that have until now lacked this elastic underlayer. The scars of full thickness wounds typically lack elasticity. Elastin is essential for skin elasticity and is enriched in the deep dermis. This paper is significant because it shows that: (1) we can generate elastic fibers in tunable quantities, (2) tropoelastin is the rate-limiting component in elastin synthesis in vitro, (3) we can generate elastin fibers regardless of donor age, (4) we describe a novel approach to further increase the numbers and thickness of elastic fibers for older donors, (5) we improve on Integra Dermal Regeneration Template and generate a new hybrid biomaterial intended to subsequently surgically deliver these elastic fibers, (6) the elastic fiber layer is presented on the side of Integra that is intended for delivery into its physiologically appropriate site i.e. the deep dermis. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Crosslinked elastic fibers are necessary for low energy loss in the ascending aorta.

PubMed

Kim, Jungsil; Staiculescu, Marius Catalin; Cocciolone, Austin J; Yanagisawa, Hiromi; Mecham, Robert P; Wagenseil, Jessica E

2017-08-16

In the large arteries, it is believed that elastin provides the resistance to stretch at low pressure, while collagen provides the resistance to stretch at high pressure. It is also thought that elastin is responsible for the low energy loss observed with cyclic loading. These tenets are supported through experiments that alter component amounts through protease digestion, vessel remodeling, normal growth, or in different artery types. Genetic engineering provides the opportunity to revisit these tenets through the loss of expression of specific wall components. We used newborn mice lacking elastin (Eln -/- ) or two key proteins (lysyl oxidase, Lox -/- , or fibulin-4, Fbln4 -/- ) that are necessary for the assembly of mechanically-functional elastic fibers to investigate the contributions of elastic fibers to large artery mechanics. We determined component content and organization and quantified the nonlinear and viscoelastic mechanical behavior of Eln -/- , Lox -/- , and Fbln4 -/- ascending aorta and their respective controls. We confirmed that the lack of elastin, fibulin-4, or lysyl oxidase leads to absent or highly fragmented elastic fibers in the aortic wall and a 56-97% decrease in crosslinked elastin amounts. We found that the resistance to stretch at low pressure is decreased only in Eln -/- aorta, confirming the role of elastin in the nonlinear mechanical behavior of the aortic wall. Dissipated energy with cyclic loading and unloading is increased 53-387% in Eln -/- , Lox -/- , and Fbln4 -/- aorta, indicating that not only elastin, but properly assembled and crosslinked elastic fibers, are necessary for low energy loss in the aorta. Copyright © 2017 Elsevier Ltd. All rights reserved.

A fiber-based constitutive model predicts changes in amount and organization of matrix proteins with development and disease in the mouse aorta

PubMed Central

Cheng, Jeffrey K.; Stoilov, Ivan; Mecham, Robert P.

2013-01-01

Decreased elastin in mice (Eln+/−) yields a functioning vascular system with elevated blood pressure and increased arterial stiffness that is morphologically distinct from wild-type mice (WT). Yet, function is retained enough that there is no appreciable effect on life span and some mechanical properties are maintained constant. It is not understood how the mouse modifies the normal developmental process to produce a functioning vascular system despite a deficiency in elastin. To quantify changes in mechanical properties, we have applied a fiber-based constitutive model to mechanical data from the ascending aorta during postnatal development of WT and Eln+/− mice. Results indicate that the fiber-based constitutive model is capable of distinguishing elastin amounts and identifying trends during development. We observe an increase in predicted circumferential stress contribution from elastin with age, which correlates with increased elastin amounts from protein quantification data. The model also predicts changes in the unloaded collagen fiber orientation with age, which must be verified in future work. In Eln+/− mice, elastin amounts are decreased at each age, along with the predicted circumferential stress contribution of elastin. Collagen amounts in Eln+/− aorta are comparable to WT, but the predicted circumferential stress contribution of collagen is increased. This may be due to altered organization or structure of the collagen fibers. Relating quantifiable changes in arterial mechanics with changes in extracellular matrix (ECM) protein amounts will help in understanding developmental remodeling and in producing treatments for human diseases affecting ECM proteins. PMID:22790326

Chronic antihypertensive treatment improves pulse pressure but not large artery mechanics in a mouse model of congenital vascular stiffness.

PubMed

Halabi, Carmen M; Broekelmann, Thomas J; Knutsen, Russell H; Ye, Li; Mecham, Robert P; Kozel, Beth A

2015-09-01

Increased arterial stiffness is a common characteristic of humans with Williams-Beuren syndrome and mouse models of elastin insufficiency. Arterial stiffness is associated with multiple negative cardiovascular outcomes, including myocardial infarction, stroke, and sudden death. Therefore, identifying therapeutic interventions that improve arterial stiffness in response to changes in elastin levels is of vital importance. The goal of this study was to determine the effect of chronic pharmacologic therapy with different classes of antihypertensive medications on arterial stiffness in elastin insufficiency. Elastin-insufficient mice 4-6 wk of age and wild-type littermates were subcutaneously implanted with osmotic micropumps delivering a continuous dose of one of the following: vehicle, losartan, nicardipine, or propranolol for 8 wk. At the end of treatment period, arterial blood pressure and large artery compliance and remodeling were assessed. Our results show that losartan and nicardipine treatment lowered blood pressure and pulse pressure in elastin-insufficient mice. Elastin and collagen content of abdominal aortas as well as ascending aorta and carotid artery biomechanics were not affected by any of the drug treatments in either genotype. By reducing pulse pressure and shifting the working pressure range of an artery to a more compliant region of the pressure-diameter curve, antihypertensive medications may mitigate the consequences of arterial stiffness, an effect that is drug class independent. These data emphasize the importance of early recognition and long-term management of hypertension in Williams-Beuren syndrome and elastin insufficiency. Copyright © 2015 the American Physiological Society.

Arterial extracellular matrix: a mechanobiological study of the contributions and interactions of elastin and collagen.

PubMed

Chow, Ming-Jay; Turcotte, Raphaël; Lin, Charles P; Zhang, Yanhang

2014-06-17

The complex network structure of elastin and collagen extracellular matrix (ECM) forms the primary load bearing components in the arterial wall. The structural and mechanobiological interactions between elastin and collagen are important for properly functioning arteries. Here, we examined the elastin and collagen organization, realignment, and recruitment by coupling mechanical loading and multiphoton imaging. Two-photon excitation fluorescence and second harmonic generation methods were performed with a multiphoton video-rate microscope to capture real time changes to the elastin and collagen structure during biaxial deformation. Enzymatic removal of elastin was performed to assess the structural changes of the remaining collagen structure. Quantitative analysis of the structural changes to elastin and collagen was made using a combination of two-dimensional fast Fourier transform and fractal analysis, which allows for a more complete understanding of structural changes. Our study provides new quantitative evidence, to our knowledge on the sequential engagement of different arterial ECM components in response to mechanical loading. The adventitial collagen exists as large wavy bundles of fibers that exhibit fiber engagement after 20% strain. The medial collagen is engaged throughout the stretching process, and prominent elastic fiber engagement is observed up to 20% strain after which the engagement plateaus. The fiber orientation distribution functions show remarkably different changes in the ECM structure in response to mechanical loading. The medial collagen shows an evident preferred circumferential distribution, however the fiber families of adventitial collagen are obscured by their waviness at no or low mechanical strains. Collagen fibers in both layers exhibit significant realignment in response to unequal biaxial loading. The elastic fibers are much more uniformly distributed and remained relatively unchanged due to loading. Removal of elastin produces similar structural changes in collagen as mechanical loading. Our study suggests that the elastic fibers are under tension and impart an intrinsic compressive stress on the collagen. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Measurement of MMP-9 and -12 degraded elastin (ELM) provides unique information on lung tissue degradation

PubMed Central

2012-01-01

Background Elastin is an essential component of selected connective tissues that provides a unique physiological elasticity. Elastin may be considered a signature protein of lungs where matrix metalloprotease (MMP) -9-and -12, may be considered the signature proteases of the macrophages, which in part are responsible for tissue damage during disease progression. Thus, we hypothesized that a MMP-9/-12 generated fragment of elastin may be a relevant biochemical maker for lung diseases. Methods Elastin fragments were identified by mass-spectrometry and one sequence, generated by MMP-9 and -12 (ELN-441), was selected for monoclonal antibody generation and used in the development of an ELISA. Soluble and insoluble elastin from lung was cleaved in vitro and the time-dependent release of fragments was assessed in the ELN-441 assay. The release of ELN-441 in human serum from patients with chronic obstructive pulmonary disease (COPD) (n = 10) and idiopathic pulmonary fibrosis (IPF) (n = 29) were compared to healthy matched controls (n = 11). Results The sequence ELN-441 was exclusively generated by MMP-9 and -12 and was time-dependently released from soluble lung elastin. ELN-441 levels were 287% higher in patients diagnosed with COPD (p < 0.001) and 124% higher in IPF patients (p < 0.0001) compared with controls. ELN-441 had better diagnostic value in COPD patients (AUC 97%, p = 0.001) than in IPF patients (AUC 90%, p = 0.0001). The odds ratios for differentiating controls from COPD or IPF were 24 [2.06–280] for COPD and 50 [2.64–934] for IPF. Conclusions MMP-9 and -12 time-dependently released the ELN-441 epitope from elastin. This fragment was elevated in serum from patients with the lung diseases IPF and COPD, however these data needs to be validated in larger clinical settings. PMID:22818364

Genetic variation in the microfibril angle of loblolly pine from two test sites

Treesearch

Jennifer H. Myszewski; Floyd E. Bridgwater; William J. Lowe; Thomas D. Byram; Robert A. Megraw

2004-01-01

In recent years, several studies have examined the effect of microfibril angle (MFA) on wood quality. However, little research has been conducted upon the genetic mechanisms controlling MFA. In this study, we examined the heritability of MFA in loblolly pine, Pinus taeda L., and its genetic relationships with height, diameter, volume, and specific...

Atomic force microscopy of torus-bearing pit membranes

Treesearch

Roland R. Dute; Thomas Elder

2011-01-01

Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the...

Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, Xiaoning; Tittmann, Bernhard; Kim, Seong H.

An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impactsmore » on the cell wall modulus, and not the cellulose microfibril packing.« less

Re-constructing our models of cellulose and primary cell wall assembly

PubMed Central

Cosgrove, Daniel J.

2014-01-01

The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. Recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin-cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Wall extensibility may be controlled at limited regions (“biomechanical hotspots”) where cellulose-cellulose contacts are made, potentially mediated by trace amounts of xyloglucan. PMID:25460077

Re-constructing our models of cellulose and primary cell wall assembly.

PubMed

Cosgrove, Daniel J

2014-12-01

The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. Recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin–cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Wall extensibility may be controlled at limited regions (‘biomechanical hotspots’) where cellulose–cellulose contacts are made, potentially mediated by trace amounts of xyloglucan.

Self-Assembly of a Modular Polypeptide Based on Blocks of Silk-Mimetic and Elastin-Mimetic Sequences

DTIC Science & Technology

2002-04-01

Silk -Mimetic and Elastin-Mimetic Sequences DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following...724 © 2002 Materials Research Society N3.8 Self-Assembly of a Modular Polypeptide based on Blocks of Silk -Mimetic and Elastin- Mimetic Sequences...Chrystelle S. Cazalis, and Vincent P. Conticello* Department of Chemistry, Emory University, Atlanta, GA 30322 ABSTRACT Spider dragline silk fiber displays

Unique Aspects of the Structure and Dynamics of Elementary Iβ Cellulose Microfibrils Revealed by Computational Simulations1[OPEN

PubMed Central

Oehme, Daniel P.; Downton, Matthew T.; Doblin, Monika S.; Wagner, John; Gidley, Michael J.; Bacic, Antony

2015-01-01

The question of how many chains an elementary cellulose microfibril contains is critical to understanding the molecular mechanism(s) of cellulose biosynthesis and regulation. Given the hexagonal nature of the cellulose synthase rosette, it is assumed that the number of chains must be a multiple of six. We present molecular dynamics simulations on three different models of Iβ cellulose microfibrils, 18, 24, and 36 chains, to investigate their structure and dynamics in a hydrated environment. The 36-chain model stays in a conformational space that is very similar to the initial crystalline phase, while the 18- and 24-chain models sample a conformational space different from the crystalline structure yet similar to conformations observed in recent high-temperature molecular dynamics simulations. Major differences in the conformations sampled between the different models result from changes to the tilt of chains in different layers, specifically a second stage of tilt, increased rotation about the O2-C2 dihedral, and a greater sampling of non-TG exocyclic conformations, particularly the GG conformation in center layers and GT conformation in solvent-exposed exocyclic groups. With a reinterpretation of nuclear magnetic resonance data, specifically for contributions made to the C6 peak, data from the simulations suggest that the 18- and 24-chain structures are more viable models for an elementary cellulose microfibril, which also correlates with recent scattering and diffraction experimental data. These data inform biochemical and molecular studies that must explain how a six-particle cellulose synthase complex rosette synthesizes microfibrils likely comprised of either 18 or 24 chains. PMID:25786828

A Structurally Specialized Uniform Wall Layer is Essential for Constructing Wall Ingrowth Papillae in Transfer Cells

PubMed Central

Xia, Xue; Zhang, Hui-Ming; Offler, Christina E.; Patrick, John W.

2017-01-01

Transfer cells are characterized by wall labyrinths with either a flange or reticulate architecture. A literature survey established that reticulate wall ingrowth papillae ubiquitously arise from a modified component of their wall labyrinth, termed the uniform wall layer; a structure absent from flange transfer cells. This finding sparked an investigation of the deposition characteristics and role of the uniform wall layer using a Vicia faba cotyledon culture system. On transfer of cotyledons to culture, their adaxial epidermal cells spontaneously trans-differentiate to a reticulate architecture comparable to their abaxial epidermal transfer cell counterparts formed in planta. Uniform wall layer construction commenced once adaxial epidermal cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear cellulose microfibrils. A re-modeled cortical microtubule array exerted no influence on uniform wall layer formation or on its cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a cellulose scaffold. In contrast, uniform wall cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the cellulose microfibril diameters increased 3-fold. This event correlated with up-regulated differential, and transfer-cell specific, expression of VfCesA3B while transcript levels of other cellulose biosynthetic-related genes linked with primary wall construction were substantially down-regulated. PMID:29259611

Roles of microtubules and cellulose microfibril assembly in the localization of secondary-cell-wall deposition in developing tracheary elements.

PubMed

Roberts, A W; Frost, A O; Roberts, E M; Haigler, C H

2004-12-01

The roles of cellulose microfibrils and cortical microtubules in establishing and maintaining the pattern of secondary-cell-wall deposition in tracheary elements were investigated with direct dyes to inhibit cellulose microfibril assembly and amiprophosmethyl to inhibit microtubule polymerization. When direct dyes were added to xylogenic cultures of Zinnia elegans L. mesophyll cells just before the onset of differentiation, the secondary cell wall was initially secreted as bands composed of discrete masses of stained material, consistent with immobilized sites of cellulose synthesis. The masses coalesced, forming truncated, sinuous or smeared thickenings, as secondary cell wall deposition continued. The absence of ordered cellulose microfibrils was confirmed by polarization microscopy and a lack of fluorescence dichroism as determined by laser scanning microscopy. Indirect immunofluorescence showed that cortical microtubules initially subtended the masses of dye-altered secondary cell wall material but soon became disorganized and disappeared. Although most of the secondary cell wall was deposited in the absence of subtending cortical microtubules in dye-treated cells, secretion remained confined to discrete regions of the plasma membrane. Examination of non-dye-treated cultures following application of microtubule inhibitors during various stages of secondary-cell-wall deposition revealed that the pattern became fixed at an early stage such that deposition remained localized in the absence of cortical microtubules. These observations indicate that cortical microtubules are required to establish, but not to maintain, patterned secondary-cell-wall deposition. Furthermore, cellulose microfibrils play a role in maintaining microtubule arrays and the integrity of the secondary-cell-wall bands during deposition.

A Structurally Specialized Uniform Wall Layer is Essential for Constructing Wall Ingrowth Papillae in Transfer Cells.

PubMed

Xia, Xue; Zhang, Hui-Ming; Offler, Christina E; Patrick, John W

2017-01-01

Transfer cells are characterized by wall labyrinths with either a flange or reticulate architecture. A literature survey established that reticulate wall ingrowth papillae ubiquitously arise from a modified component of their wall labyrinth, termed the uniform wall layer; a structure absent from flange transfer cells. This finding sparked an investigation of the deposition characteristics and role of the uniform wall layer using a Vicia faba cotyledon culture system. On transfer of cotyledons to culture, their adaxial epidermal cells spontaneously trans -differentiate to a reticulate architecture comparable to their abaxial epidermal transfer cell counterparts formed in planta . Uniform wall layer construction commenced once adaxial epidermal cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear cellulose microfibrils. A re-modeled cortical microtubule array exerted no influence on uniform wall layer formation or on its cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a cellulose scaffold. In contrast, uniform wall cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the cellulose microfibril diameters increased 3-fold. This event correlated with up-regulated differential, and transfer-cell specific, expression of VfCesA3B while transcript levels of other cellulose biosynthetic-related genes linked with primary wall construction were substantially down-regulated.

Relationships of density, microfibril angle, and sound velocity with stiffness and strength in mature wood of Douglas-fir

Treesearch

B. Lachenbruch; G.R. Johnson; G.M. Downes; R. Evans

2010-01-01

The relative importance of density, acoustic velocity, and microfibril angle (MFA) for the prediction of stiffness (MOE) and strength (MOR) has not been well established for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). MOE and MOR of small clear specimens of mature wood were better predicted by density and velocity than by either variable...

Microfibril angle in wood of Scots pine trees (Pinus sylvestris) after irradiation from the Chernobyl nuclear reactor accident.

PubMed

Tulik, Mirela; Rusin, Aleksandra

2005-03-01

The secondary cell wall structure of tracheids of Scots pine (Pinus sylvestris L.), especially the angle of microfibrils in the S(2) layer, was examined in wood deposited prior to and after the Chernobyl accident in 1986. Microscopic analysis was carried out on wood samples collected in October 1997 from breast height of three pine trees 16, 30 and 42 years old. The polluted site was located in a distance of 5 km south from the Chernobyl nuclear power plant where radioactive contamination in 1997 was 3.7 x 10(5) kBq m(-2). Anatomical analysis showed that the structure of the secondary cell wall in tracheids formed after the Chernobyl accident was changed. Changes occurred both in S(2) and S(3) layers. The angle of microfibrils in S(2) layer in wood deposited after the Chernobyl accident was different in comparison to this measured in wood formed prior to the disaster. The intensity of the changes, i.e. alteration of the microfibrils angle in S(2) layer and unusual pattern of the S(3) layer, depended on the age of the tree and was most intensive in a young tree.

Microtubule and cellulose microfibril orientation during plant cell and organ growth.

PubMed

Chan, J

2012-07-01

In this review, I ask the question of what is the relationship between growth and the orientations of microtubules and cellulose microfibrils in plant cells. This should be a relatively simple question to answer considering that text books commonly describe microtubules and cellulose microfibrils as hoops that drive expansion perpendicular to their orientation. However, recent live imaging techniques, which allow microtubules and cellulose synthase dynamics to be imaged simultaneously with cell elongation, show that cells can elongate with nonperpendicular microtubule arrays. In this review, I look at the significance of these different microtubule arrangements for growth and cell wall architecture and how these resultant walls differ from those derived from perpendicular arrays. I also discuss how these divergent arrays in stems may be important for coordinating growth between the different cell layers. This role reveals some general features of microtubule alignment that can be used to predict the growth status of organs. In conclusion, nonperpendicular arrays demonstrate alternative ways of cell elongation that do not require hooped arrays of microtubules and cellulose microfibrils. Such nonperpendicular arrays may be required for optimal growth and strengthening of tissues. © 2011 The Author Journal of Microscopy © 2011 Royal Microscopical Society.

Influence of elastin-derived peptides on metalloprotease production in endothelial cells.

PubMed

Siemianowicz, Krzysztof; Gminski, Jan; Goss, Malgorzata; Francuz, Tomasz; Likus, Wirginia; Jurczak, Teresa; Garczorz, Wojciech

2010-11-01

Matrix metalloproteases (MMPs) are a family of zinc-dependent endopeptidases that degrade extracellular matrix proteins. MMP-1 and MMP-2 are produced by endothelial cells and are involved in specific vascular pathologies, including atherosclerosis and aortal aneurysm. One of the most important differences between these two metalloproteases is the possibility of hydrolysis of elastin and collagen type IV by MMP-2, but not by MMP-1. Elastin-derived peptides are generated as a result of the degradation of elastin fibers. The aim of our study was to compare the production of MMP-1 and MMP-2 in cultured human arterial endothelial cells derived from vascular pathologies localized at three different sites, the coronary artery, iliac artery and aorta, measured as their concentration in cell culture medium. The second aim was to evaluate the influence of κ-elastin (at concentrations 0.1, 0.4, 1.0, 2.5 or 5.0 μg/ml) on the production of the evaluated metalloproteases in three endothelial cell lines. The production of MMP-1 was statistically significantly greater in endothelial cells derived from the aorta compared to that in the endothelium obtained from the coronary and iliac arteries. There were no statistically significant differences in the production of MMP-2 among the endothelial cell lines tested. The addition of κ-elastin at all evaluated concentrations did not statistically significantly influence the concentration of MMP-1 in the cultured coronary artery endothelium. Furthermore, no statistically significant differences were observed in the cultured iliac artery endothelium. In the cultured endothelium derived from the aorta, κ-elastin at concentrations of 0.1 and 0.4 μg/ml significantly increased the amount of MMP-1.

Influence of elastin-derived peptides on metalloprotease production in endothelial cells

PubMed Central

SIEMIANOWICZ, KRZYSZTOF; GMINSKI, JAN; GOSS, MALGORZATA; FRANCUZ, TOMASZ; LIKUS, WIRGINIA; JURCZAK, TERESA; GARCZORZ, WOJCIECH

2010-01-01

Matrix metalloproteases (MMPs) are a family of zinc-dependent endopeptidases that degrade extracellular matrix proteins. MMP-1 and MMP-2 are produced by endothelial cells and are involved in specific vascular pathologies, including atherosclerosis and aortal aneurysm. One of the most important differences between these two metalloproteases is the possibility of hydrolysis of elastin and collagen type IV by MMP-2, but not by MMP-1. Elastin-derived peptides are generated as a result of the degradation of elastin fibers. The aim of our study was to compare the production of MMP-1 and MMP-2 in cultured human arterial endothelial cells derived from vascular pathologies localized at three different sites, the coronary artery, iliac artery and aorta, measured as their concentration in cell culture medium. The second aim was to evaluate the influence of κ-elastin (at concentrations 0.1, 0.4, 1.0, 2.5 or 5.0 μg/ml) on the production of the evaluated metalloproteases in three endothelial cell lines. The production of MMP-1 was statistically significantly greater in endothelial cells derived from the aorta compared to that in the endothelium obtained from the coronary and iliac arteries. There were no statistically significant differences in the production of MMP-2 among the endothelial cell lines tested. The addition of κ-elastin at all evaluated concentrations did not statistically significantly influence the concentration of MMP-1 in the cultured coronary artery endothelium. Furthermore, no statistically significant differences were observed in the cultured iliac artery endothelium. In the cultured endothelium derived from the aorta, κ-elastin at concentrations of 0.1 and 0.4 μg/ml significantly increased the amount of MMP-1. PMID:22993640

Synthetic ligands of the elastin receptor induce elastogenesis in human dermal fibroblasts via activation of their IGF-1 receptors.

PubMed

Qa'aty, Nour; Vincent, Matthew; Wang, Yanting; Wang, Andrew; Mitts, Thomas F; Hinek, Aleksander

2015-12-01

We have previously reported that a mixture of peptides obtained after chemical or enzymatic degradation of bovine elastin, induced new elastogenesis in human skin. Now, we investigated the elastogenic potential of synthetic peptides mimicking the elastin-derived, VGVAPG sequence, IGVAPG sequence that we found in the rice bran, and a similar peptide, VGVTAG that we identified in the IGF-1-binding protein-1 (IGFBP-1). We now demonstrate that treatment with each of these xGVxxG peptides (recognizable by the anti-elastin antibody), up-regulated the levels of elastin-encoding mRNA, tropoelastin protein, and the deposition of new elastic fibers in cultures of human dermal fibroblasts and in cultured explants of human skin. Importantly, we found that such induction of new elastogenesis may involve two parallel signaling pathways triggered after activation of IGF-1 receptor. In the first one, the xGVxxG peptides interact with the cell surface elastin receptor, thereby causing the downstream activation of the c-Src kinase and a consequent cross-activation of the adjacent IGF-1R, even in the absence of its principal ligand. In the second pathway their hydrophobic association with the N-terminal domain (VGVTAG) of the serum-derived IGFBP-1 induces conformational changes of this IGF-1 chaperone allowing for the release of its cargo and a consequent ligand-specific phosphorylation of IGF-1R. We present a novel, clinically relevant mechanism in which products of partial degradation of dermal elastin may stimulate production of new elastic fibers by dermal fibroblasts. Our findings particularly encourage the use of biologically safe synthetic xGVxxG peptides for regeneration of the injured or aged human skin. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Effects of birth trauma and estrogen on urethral elastic fibers and elastin expression.

PubMed

Lin, Guiting; Ning, Hongxiu; Wang, Guifang; Banie, Lia; Lue, Tom F; Lin, Ching-Shwun

2010-10-01

To investigate the effects of birth trauma and estrogen on urethral elastic fibers and elastin expression. Pregnant rats were subjected to sham operation (Delivery-only), DVDO (delivery, vaginal distension and ovariectomy), or DVDO + E₂ (estrogen). At 2, 4, 8, or 12 weeks, their urethras were harvested for elastic fiber staining and reverse transcription-polymerase chain reaction analysis. Urethral cells were treated with transforming growth factor- β1 (TGFβ1) and/or estrogen and analyzed for elastin mRNA expression. Urethral cells were also examined for the activities of Smad1- and Smad3/4-responsive elements in response to TGFβ1 and estrogen. At 8 weeks post-treatment, the urethras of DVDO rats had fewer and shorter elastic fibers when compared with Delivery-only rats, and those of DVDO + E₂ rats had fewer and shorter elastic fibers when compared with DVDO rats. Elastin mRNA was expressed at low levels in Delivery-only rats and at increasingly higher levels in DVDO rats at 2, 4, and 8 weeks but at sharply lower levels in DVDO + E₂ rats when compared with DVDO rats at 8 weeks. Urethral cells expressed increasingly higher levels of elastin mRNA in response to increasing concentrations of TGFβ1 up to 1 ng/mL. At this TGFβ1 concentration, urethral cells expressed significantly lower levels of elastin mRNA when treated with estrogen before or after TGFβ1 treatment. Both Smad1- and Smad3/4-responsive elements were activated by TGFβ1 and such activation was suppressed by estrogen. Birth trauma appears to activate urethral elastin expression via TGFβ1 signaling. Estrogen interferes with this signaling, resulting in improper assembly of elastic fibers. Copyright © 2010 Elsevier Inc. All rights reserved.

Monitoring wound healing by multiphoton tomography/endoscopy

NASA Astrophysics Data System (ADS)

König, Karsten; Weinigel, Martin; Bückle, Rainer; Kaatz, Martin; Hipler, Christina; Zens, Katharina; Schneider, Stefan W.; Huck, Volker

2015-02-01

Certified clinical multiphoton tomographs are employed to perform rapid label-free high-resolution in vivo histology. Novel tomographs include a flexible 360° scan head attached to a mechano-optical arm for autofluorescence and SHG imaging as well as rigid two-photon GRIN microendoscope. Mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged with submicron resolution in human skin. The system was employed to study the healing of chronic wounds (venous leg ulcer) and acute wounds (curettage of actinic or seborrheic keratosis) on a subcellular level. Furthermore, a flexible sterile foil as interface between wound and focusing optic was tested.

Elephantiasis, elastin, and chronic wound healing: 19th century and contemporary viewpoints relevant to hypotheses concerning lymphedema, leprosy, erysipelas, and psoriasis--review and reflections.

PubMed

Ryan, T J

2009-03-01

Both wound healing and lymphedema have fibrosis of the skin in common. They also share destruction of elastin by elastases from neutrophils as a significant feature. These are not new observations, and the writings of Unna and Kaposi are recalled. The contemporary observations on elastin by Gerli and his team are discussed in the light of these much earlier opinions.

Development of Intra-Articular Drug Delivery to Alter Progression of Arthritis Following Joint Injury

DTIC Science & Technology

2012-04-01

2012Revised AnnualApril 2012 DESIGN: A novel injectable and in situ forming drug depot based on thermally-responsive elastin -like polypeptide (ELP) will... Elastin -like polypeptide, Drug Depot – technology allowing sustained release of biologically active agent , Active agents used include IL1Ra...The abstract has been removed and an appendix has been included. In brief this protocol explores the use of elastin like polypeptide (ELP) as a

Oxygenation decreases elastin secretion from rat ductus arteriosus smooth muscle cells.

PubMed

Kawakami, Shoji; Minamisawa, Susumu

2015-08-01

The ductus arteriosus (DA), a fetal arterial connection between the main pulmonary artery and the descending aorta, normally closes immediately after birth. The oxygen concentration in the blood rises after birth, and in the DA this increase in oxygen concentration causes functional closure, which is induced by smooth muscle contraction. Previous studies have demonstrated that hypoxia and/or oxygenation affect vascular remodeling of various vessels. Therefore, we hypothesized that the rise in oxygen concentration would affect the vascular structure of the DA due to production of proteins secreted from DA smooth muscle cells (SMC). Liquid chromatography-tandem mass spectrometry was used to comprehensively investigate the secreted proteins in the supernatant of rat DA SMC harvested under hypoxic conditions (1% oxygen) or under normoxic conditions (21% oxygen). We found that the rise in oxygen concentration reduced the secretion of elastin from DA SMC. On reverse transcription-polymerase chain reaction, the expression of elastin mRNA was not significantly changed in DA SMC from hypoxic to normoxic conditions. Given that elastin forms internal elastic lamina and elastic fibers in the vascular muscle layers, and that a rise in oxygen concentration reduced the secretion of elastin, this suggests that the rise in blood oxygen concentration after birth reduces the secretion of elastin, and therefore may play a role in DA structural remodeling after birth. © 2015 Japan Pediatric Society.

Effects of solvent concentration and composition on protein dynamics: 13C MAS NMR studies of elastin in glycerol-water mixtures.

PubMed

Demuth, Dominik; Haase, Nils; Malzacher, Daniel; Vogel, Michael

2015-08-01

We use (13)C CP MAS NMR to investigate the dependence of elastin dynamics on the concentration and composition of the solvent at various temperatures. For elastin in pure glycerol, line-shape analysis shows that larger-scale fluctuations of the protein backbone require a minimum glycerol concentration of ~0.6 g/g at ambient temperature, while smaller-scale fluctuations are activated at lower solvation levels of ~0.2 g/g. Immersing elastin in various glycerol-water mixtures, we observe at room temperature that the protein mobility is higher for lower glycerol fractions in the solvent and, thus, lower solvent viscosity. When decreasing the temperature, the elastin spectra approach the line shape for the rigid protein at 245 K for all studied samples, indicating that the protein ceases to be mobile on the experimental time scale of ~10(-5) s. Our findings yield evidence for a strong coupling between elastin fluctuations and solvent dynamics and, hence, such interaction is not restricted to the case of protein-water mixtures. Spectral resolution of different carbon species reveals that the protein-solvent couplings can, however, be different for side chain and backbone units. We discuss these results against the background of the slaving model for protein dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural and Functional Differences Between Porcine Aorta and Vena Cava.

PubMed

Mattson, Jeffrey M; Zhang, Yanhang

2017-07-01

Elastin and collagen fibers are the major load-bearing extracellular matrix (ECM) constituents of the vascular wall. Arteries function differently than veins in the circulatory system; however as a result from several treatment options, veins are subjected to sudden elevated arterial pressure. It is thus important to recognize the fundamental structure and function differences between a vein and an artery. Our research compared the relationship between biaxial mechanical function and ECM structure of porcine thoracic aorta and inferior vena cava. Our study suggests that aorta contains slightly more elastin than collagen due to the cyclical extensibility, but vena cava contains almost four times more collagen than elastin to maintain integrity. Furthermore, multiphoton imaging of vena cava showed longitudinally oriented elastin and circumferentially oriented collagen that is recruited at supraphysiologic stress, but low levels of strain. However in aorta, elastin is distributed uniformly, and the primarily circumferentially oriented collagen is recruited at higher levels of strain than vena cava. These structural observations support the functional finding that vena cava is highly anisotropic with the longitude being more compliant and the circumference stiffening substantially at low levels of strain. Overall, our research demonstrates that fiber distributions and recruitment should be considered in addition to relative collagen and elastin contents. Also, the importance of accounting for the structural and functional differences between arteries and veins should be taken into account when considering disease treatment options.

Knockdown of versican 1 blocks cigarette-induced loss of insoluble elastin in human lung fibroblasts.

PubMed

Xu, Lu-lu; Lu, Yun-tao; Zhang, Jing; Wu, Lian; Merrilees, Mervyn J; Qu, Jie-ming

2015-08-15

COPD lung is characterized by loss of alveolar elastic fibers and an increase in the chondroitin sulfate (CS) matrix proteoglycan versican V1 (V1). V1 is a known inhibitor of elastic fiber deposition and this study investigates the effects of knockdown of V1, and add-back of CS, on CCL-210 lung fibroblasts treated with cigarette smoke extract (CSE) as a model for COPD. CSE inhibited fibroblast proliferation, viability, tropoelastin synthesis, and elastin deposition, and increased V1 synthesis and secretion. V1 siRNA decreased V1 and constituent CS, did not affect tropoelastin production, but blocked the CSE-induced loss in insoluble elastin. Exogenous CS reduced insoluble elastin, even in the presence of V1 siRNA. These findings confirm that V1 and CS impair the assembly of tropoelastin monomers into insoluble fibers, and further demonstrate that specific knockdown of V1 alleviates the impaired assembly of elastin seen in cultures of pulmonary fibroblasts exposed to CSE, indicating a regulatory role for this protein in the pathophysiology of COPD. Copyright © 2015 Elsevier B.V. All rights reserved.

Matrix ageing and vascular impacts: focus on elastin fragmentation.

PubMed

Duca, Laurent; Blaise, Sébastien; Romier, Béatrice; Laffargue, Muriel; Gayral, Stéphanie; El Btaouri, Hassan; Kawecki, Charlotte; Guillot, Alexandre; Martiny, Laurent; Debelle, Laurent; Maurice, Pascal

2016-06-01

Cardiovascular diseases (CVDs) are the leading cause of death worldwide and represent a major problem of public health. Over the years, life expectancy has considerably increased throughout the world, and the prevalence of CVD is inevitably rising with the growing ageing of the population. The normal process of ageing is associated with progressive deterioration in structure and function of the vasculature, commonly called vascular ageing. At the vascular level, extracellular matrix (ECM) ageing leads to molecular alterations in long half-life proteins, such as elastin and collagen, and have critical effects on vascular diseases. This review highlights ECM alterations occurring during vascular ageing with a specific focus on elastin fragmentation and also the contribution of elastin-derived peptides (EDP) in age-related vascular complications. Moreover, current and new pharmacological strategies aiming at minimizing elastin degradation, EDP generation, and associated biological effects are discussed. These strategies may be of major relevance for preventing and/or delaying vascular ageing and its complications. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Re-constructing our models of cellulose and primary cell wall assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cosgrove, Daniel J.

2014-11-16

The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. We report that recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin-cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Finally,more » wall extensibility may be controlled at limited regions (“biomechanical hotspots”) where cellulose-cellulose contacts are made, potentially mediated by trace amounts of xyloglucan.« less

Calcofluor white ST Alters the in vivo assembly of cellulose microfibrils.

PubMed

Haigler, C H; Brown, R M; Benziman, M

1980-11-21

The fluorescent brightener, Calcofluor White ST, prevents the in vivo assembly of crystalline cellulose microfibrils and ribbons by Acetobacter xylinum. In the presence of more than 0.01 percent Calcofluor, Acetobacter continues to synthesize high-molecular-weight beta-1,4 glucans. X-ray crystallography shows that the altered product exhibits no detectable crystallinity in the wet state, but upon drying it changes into crystalline cellulose I. Calcofluor alters cellulose crystallization by hydrogen bonding with glucan chains. Synthesis of this altered product is reversible and can be monitored with fluorescence and electron microscopy. Use of Calcofluor has made it possible to separate the processes of polymerization and crystallization leading to the biogenesis of cellulose microfibrils, and has suggested that crystallization occurs by a cell-directed. self-assembly process in Acetobacter xylinum.

Multi-Mode Binding of Cellobiohydrolase Cel7A from Trichoderma reesei to Cellulose

PubMed Central

Jalak, Jürgen; Väljamäe, Priit

2014-01-01

Enzymatic hydrolysis of recalcitrant polysaccharides like cellulose takes place on the solid-liquid interface. Therefore the adsorption of enzymes to the solid surface is a pre-requisite for catalysis. Here we used enzymatic activity measurements with fluorescent model-substrate 4-methyl-umbelliferyl-β-D-lactoside for sensitive monitoring of the binding of cellobiohydrolase TrCel7A from Trichoderma reesei to bacterial cellulose (BC). The binding at low nanomolar free TrCel7A concentrations was exclusively active site mediated and was consistent with Langmuir's one binding site model with K d and A max values of 2.9 nM and 126 nmol/g BC, respectively. This is the strongest binding observed with non-complexed cellulases and apparently represents the productive binding of TrCel7A to cellulose chain ends on the hydrophobic face of BC microfibril. With increasing free TrCel7A concentrations the isotherm gradually deviated from the Langmuir's one binding site model. This was caused by the increasing contribution of lower affinity binding modes that included both active site mediated binding and non-productive binding with active site free from cellulose chain. The binding of TrCel7A to BC was found to be only partially reversible. Furthermore, the isotherm was dependent on the concentration of BC with more efficient binding observed at lower BC concentrations. The phenomenon can be ascribed to the BC concentration dependent aggregation of BC microfibrils with concomitant reduction of specific surface area. PMID:25265511

Elasticity and Inverse Temperature Transition in Elastin

DOE PAGES

Perticaroli, Stefania; Ehlers, Georg; Jalarvo, Niina; ...

2015-09-22

Structurally, elastin is protein and biomaterial that provides elasticity and resilience to a range of tissues. This work provides insights into the elastic properties of elastin and its peculiar inverse temperature transition (ITT). These features are dependent on hydration of elastin and are driven by a similar mechanism of hydrophobic collapse to an entropically favorable state. Moreover, when using neutron scattering, we quantify the changes in the geometry of molecular motions above and below the transition temperature, showing a reduction in the displacement of water-induced motions upon hydrophobic collapse at the ITT. Finally, we measured the collective vibrations of elastinmore » gels as a function of elongation, revealing no changes in the spectral features associated with local rigidity and secondary structure, in agreement with the entropic origin of elasticity.« less

Visualization of dermal alteration in skin lesions with discoid lupus erythematosus by multiphoton microscopy

NASA Astrophysics Data System (ADS)

Lin, L. H.; Yu, H. B.; Zhu, X. Q.; Zhuo, S. M.; Wang, Y. Y.; Yang, Y. H.; Chen, J. X.

2013-04-01

Discoid lupus erythematosus (DLE) is a chronic dermatological disease which lacks valid methods for early diagnosis and therapeutic monitoring. Considering the collagen and elastin disorder due to mucin deposition of DLE, multiphoton microscopy (MPM) imaging techniques were employed to obtain high-resolution collagen and elastin images from the dermis. The content and distribution of collagen and elastin were quantified to characterize the dermal pathological status of skin lesions with DLE in comparison with normal skin. Our results showed a significant difference between skin lesions with DLE and normal skin in terms of the morphological structure of collagen and elastin in the dermis, demonstrating the possibility of MPM for noninvasively tracking the pathological process of DLE even in its early stages and evaluating the therapeutic efficacy at the molecular level.

Raman microspectroscopy as a diagnostic tool for the non-invasive analysis of fibrillin-1 deficiency in the skin and in the in vitro skin models.

PubMed

Brauchle, Eva; Bauer, Hannah; Fernes, Patrick; Zuk, Alexandra; Schenke-Layland, Katja; Sengle, Gerhard

2017-04-01

Fibrillin microfibrils and elastic fibers are critical determinants of elastic tissues where they define as tissue-specific architectures vital mechanical properties such as pliability and elastic recoil. Fibrillin microfibrils also facilitate elastic fiber formation and support the association of epithelial cells with the interstitial matrix. Mutations in fibrillin-1 (FBN1) are causative for the Marfan syndrome, a congenital multisystem disorder characterized by progressive deterioration of the fibrillin microfibril/ elastic fiber architecture in the cardiovascular, musculoskeletal, ocular, and dermal system. In this study, we utilized Raman microspectroscopy in combination with principal component analysis (PCA) to analyze the molecular consequences of fibrillin-1 deficiency in skin of a mouse model (GT8) of Marfan syndrome. In addition, full-thickness skin models incorporating murine wild-type and Fbn1 GT8/GT8 fibroblasts as well as human HaCaT keratinocytes were generated and analyzed. Skin models containing GT8 fibroblasts showed an altered epidermal morphology when compared to wild-type models indicating a new role for fibrillin-1 in dermal-epidermal crosstalk. Obtained Raman spectra together with PCA allowed to discriminate between healthy and deficient microfibrillar networks in murine dermis and skin models. Interestingly, results obtained from GT8 dermis and skin models showed similar alterations in molecular signatures triggered by fibrillin-1 deficiency such as amide III vibrations and decreased levels of glycan vibrations. Overall, this study indicates that Raman microspectroscopy has the potential to analyze subtle changes in fibrillin-1 microfibrils and elastic fiber networks. Therefore Raman microspectroscopy may be utilized as a non-invasive and sensitive diagnostic tool to identify connective tissue disorders and monitor their disease progression. Mutations in building blocks of the fibrillin microfibril/ elastic fiber network manifest in disease conditions such as aneurysms, emphysema or lax skin. Understanding how structural changes induced by fibrillin-1 mutation impact the architecture of fibrillin microfibrils, which then translates into an altered activation state of targeted growth factors, represents a huge challenge in elucidating the genotype-phenotype correlations in connective tissue disorders such as Marfan syndrome. This study shows that Raman microspectroscopy is able to reveal structural changes in fibrillin-1 microfibrils and elastic fiber networks and to discriminate between normal and diseased networks in vivo and in vitro. Therefore Raman microspectroscopy may be utilized as a non-invasive and sensitive diagnostic tool to identify connective tissue disorders and monitor their disease progression. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fabrication of microfibrillated cellulose gel from waste pulp sludge via mild maceration combined with mechanical shearing

Treesearch

Nusheng Chen; Junyong Zhu; Zhaohui Tong

2016-01-01

This article describes a facile route, which combines mild maceration of waste pulp sludge and a mechanical shearing process, to prepare microfibrillated cellulose (MFC) with a high storage modulus. In the maceration, the mixture of glacial acetic acid and hydrogen peroxide was used to extract cellulose from never-dried waste pulp sludge. Then, two different mechanical...

Rapid analysis of the microfibril angle of loblolly pine from two test sites using near-infrared analysis

Treesearch

ChiLeung So; Jennifer Myszewski; Thomas Elder; Les Groom

2013-01-01

Abstract There have been several recent studies employing near infrared (NIR) spectroscopy for the rapid determination of microfibril angle (MFA). However, only a few have utilized samples cut from individual rings of increment cores, and none have been as large as this present study, sampling over 600 trees from two test sites producing over 3000 individual ring...

Mechanical Properties versus Morphology of Ordered Polymers

DTIC Science & Technology

1980-05-01

for a similar banding observed in PPTA 30 fibers. The dark field results suggest each microfibril ribbon consists of a succession of narrow...transmission electron microscopy may be obtained by surface tension aided microfibril dispersion. The longitudinal sections of fibers obtained by...the value of c ( 0.08) obtained for native and regenerated cellulose , another class of stiff chain polymers16). (Deriva- tives of cellulose can be spun

Ultrastructure Processing of Ordered Polymers

DTIC Science & Technology

1990-01-18

from regenerated cellulose , then from synthetic polymer consisting of chemical raw materials derived from oils and coal. Since then, some scientists have...ordered crystal- line material, crystallite, throughout the fiber, which is composed of microfibrils and fibrils. The small crystallites are regularly...these flat ribbons appears to consist of smaller " microfibrils " of lateral dimension varying from 50-80 A, as described before(Figs. 15 and 16). These

JMFA2—a graphically interactive Java program that fits microfibril angle X-ray diffraction data

Treesearch

Steve P. Verrill; David E. Kretschmann; Victoria L. Herian

2006-01-01

X-ray diffraction techniques have the potential to decrease the time required to determine microfibril angles dramatically. In this paper, we discuss the latest version of a curve-fitting toll that permits us to reduce the time required to evaluate MFA X-ray diffraction patterns. Further, because this tool reflects the underlying physics more accurately than existing...

Variation in loblolly pine ring microfibril angle in the southeastern United States

Treesearch

Lewis Jordan; Rechun He; Daniel B. Hall; Alexander III Clark; Richard F. Daniels

2007-01-01

The effect of physiographic region on microfibril angle (MFA) in loblolly pine (Pinus taeda L.) in the southern United States was evaluated. MFA was determined at 1.4, 4.6, 7.6, 10.7, and 13.7 m up the stem of 59 trees, representing five physiographic regions. A nonlinear mixed-effects model was developed to test for regional differences in the...

Multilevel nonlinear mixed-effects models for the modeling of earlywood and latewood microfibril angle

Treesearch

Lewis Jordon; Richard F. Daniels; Alexander Clark; Rechun He

2005-01-01

Earlywood and latewood microfibril angle (MFA) was determined at I-millimeter intervals from disks at 1.4 meters, then at 3-meter intervals to a height of 13.7 meters, from 18 loblolly pine (Pinus taeda L.) trees grown in southeastern Texas. A modified three-parameter logistic function with mixed effects is used for modeling earlywood and latewood...

Mechanical response of longleaf pine to variation in microfibril angle, chemistry associated wavelengths, density, and radial position

Treesearch

B. K. Via; C. L. So; T. F. Shupe; L. H. Groom; J. Wikaira

2009-01-01

The composite structure of the S2 layer in the wood cell wall is defined by the angle of the cellulose microfibrils and concentration of polymers and this structure impacts strength and stiffness. The objective of this study was to use near infrared spectroscopy and X-ray diffraction to determine the effect of lignin and cellulose associated wavelengths,...

Elastin Based Cell-laden Injectable Hydrogels with Tunable Gelation, Mechanical and Biodegradation Properties

PubMed Central

Fathi, Ali; Mithieux, Suzanne M.; Wei, Hua; Chrzanowski, Wojciech; Valtchev, Peter; Weiss, Anthony S.; Dehghani, Fariba

2015-01-01

Injectable hydrogels made from extracellular matrix proteins such as elastin show great promise for various biomedical applications. Use of cytotoxic reagents, fixed gelling behavior, and lack of mechanical strength in these hydrogels are the main associated drawbacks. The aim of this study was to develop highly cytocompatible and injectable elastin-based hydrogels with alterable gelation characteristics, favorable mechanical properties and structural stability for load bearing applications. A thermoresponsive copolymer, poly(N-isopropylacrylamide-co-polylactide-2-hydroxyethyl methacrylate-co-oligo(ethylene glycol)monomethyl ether methacrylate, was functionalized with succinimide ester groups by incorporating N-acryloxysuccinimide monomer. These ester groups were exploited to covalently bond this polymer, denoted as PNPHO, to different proteins with primary amine groups such as α-elastin in aqueous media. The incorporation of elastin through covalent bond formation with PNPHO promotes the structural stability, mechanical properties and live cell proliferation within the structure of hydrogels. Our results demonstrated that elastin-co-PNPHO solutions were injectable through fine gauge needles and converted to hydrogels in situ at 37 °C in the absence of any crosslinking reagent. By altering PNPHO content, the gelling time of these hydrogels can be finely tuned within the range of 2 to 15 min to ensure compatibility with surgical requirements. In addition, these hydrogels exhibited compression moduli in the range of 40 to 145 kPa, which are substantially higher than those of previously developed elastin-based hydrogels. These hydrogels were highly stable in the physiological environment with the evidence of 10 wt% mass loss in 30 days of incubation in a simulated environment. This class of hydrogels is in vivo bioabsorbable due to the gradual increase of the lower critical solution temperature of the copolymer to above 37 °C due to the cleavage of polylactide from the PNPHO copolymer. Moreover, our results demonstrated that more than 80% of cells encapsulated in these hydrogels remained viable, and the number of encapsulated cells increased for at least 5 days. These unique properties mark elastin-co-PNHPO hydrogels as favorable candidates for a broad range of tissue engineering applications. PMID:24731705

Elastin is a key regulator of outward remodeling in arteriovenous fistulas.

PubMed

Wong, C Y; Rothuizen, T C; de Vries, M R; Rabelink, T J; Hamming, J F; van Zonneveld, A J; Quax, P H A; Rotmans, J I

2015-04-01

Maturation failure is the major limitation of arteriovenous fistulas (AVFs) as hemodialysis access conduits. Indeed, 30-50% of AVFs fail to mature due to intimal hyperplasia and insufficient outward remodeling. Elastin has emerged as an important determinant of vascular remodeling. Here the role of elastin in AVF remodeling in elastin haplodeficient (eln(+/-)) mice undergoing AVF surgery has been studied. Unilateral AVFs between the branch of the jugular vein and carotid artery in an end to side manner were created in wild-type (WT) C57BL/6 (n = 11) and in eln(+/-) mice (n = 9). Animals were killed at day 21 and the AVFs were analyzed histologically and at an mRNA level using real-time quantitative polymerase chain reaction. Before AVF surgery, a marked reduction in elastin density in the internal elastic lamina (IEL) of eln(+/-) mice was observed. AVF surgery resulted in fragmentation of the venous internal elastic lamina in both groups while the expression of the tropoelastin mRNA was 53% lower in the eln(+/-) mice than in WT mice (p < .001). At 21 days after AVF surgery, the circumference of the venous outflow tract of the AVF was 21% larger in the eln(+/-) mice than in the WT mice (p = .037), indicating enhanced outward remodeling in the eln(+/-) mice. No significant difference in intimal hyperplasia was observed. The venous lumen of the AVF in the eln(+/-) mice was 53% larger than in the WT mice, although this difference was not statistically significant (eln(+/-), 350,116 ± 45,073 μm(2); WT, 229,405 ± 40,453 μm(2); p = .064). In a murine model, elastin has an important role in vascular remodeling following AVF creation, in which a lower amount of elastin results in enhanced outward remodeling. Interventions targeting elastin degradation might be a viable option in order to improve AVF maturation. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase.

PubMed

Cho, Sung Hyun; Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Díaz-Moreno, Sara M; Bulone, Vincent; Zimmer, Jochen; Kumar, Manish; Nixon, B Tracy

2017-09-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. © 2017 American Society of Plant Biologists. All Rights Reserved.

Unique aspects of the structure and dynamics of elementary Iβ cellulose microfibrils revealed by computational simulations.

PubMed

Oehme, Daniel P; Downton, Matthew T; Doblin, Monika S; Wagner, John; Gidley, Michael J; Bacic, Antony

2015-05-01

The question of how many chains an elementary cellulose microfibril contains is critical to understanding the molecular mechanism(s) of cellulose biosynthesis and regulation. Given the hexagonal nature of the cellulose synthase rosette, it is assumed that the number of chains must be a multiple of six. We present molecular dynamics simulations on three different models of Iβ cellulose microfibrils, 18, 24, and 36 chains, to investigate their structure and dynamics in a hydrated environment. The 36-chain model stays in a conformational space that is very similar to the initial crystalline phase, while the 18- and 24-chain models sample a conformational space different from the crystalline structure yet similar to conformations observed in recent high-temperature molecular dynamics simulations. Major differences in the conformations sampled between the different models result from changes to the tilt of chains in different layers, specifically a second stage of tilt, increased rotation about the O2-C2 dihedral, and a greater sampling of non-TG exocyclic conformations, particularly the GG conformation in center layers and GT conformation in solvent-exposed exocyclic groups. With a reinterpretation of nuclear magnetic resonance data, specifically for contributions made to the C6 peak, data from the simulations suggest that the 18- and 24-chain structures are more viable models for an elementary cellulose microfibril, which also correlates with recent scattering and diffraction experimental data. These data inform biochemical and molecular studies that must explain how a six-particle cellulose synthase complex rosette synthesizes microfibrils likely comprised of either 18 or 24 chains. © 2015 American Society of Plant Biologists. All Rights Reserved.

Mutant alleles of Arabidopsis RADIALLY SWOLLEN 4 and 7 reduce growth anisotropy without altering the transverse orientation of cortical microtubules or cellulose microfibrils.

PubMed

Wiedemeier, Allison M D; Judy-March, Jan E; Hocart, Charles H; Wasteneys, Geoffrey O; Williamson, Richard E; Baskin, Tobias I

2002-10-01

The anisotropic growth of plant cells depends on cell walls having anisotropic mechanical properties, which are hypothesized to arise from aligned cellulose microfibrils. To test this hypothesis and to identify genes involved in controlling plant shape, we isolated mutants in Arabidopsis thaliana in which the degree of anisotropic expansion of the root is reduced. We report here the characterization of mutants at two new loci, RADIALLY SWOLLEN 4 (RSW4) and RSW7. The radial swelling phenotype is temperature sensitive, being moderate (rsw7) or negligible (rsw4) at the permissive temperature, 19 degrees C, and pronounced at the restrictive temperature, 30 degrees C. After transfer to 30 degrees C, the primary root's elongation rate decreases and diameter increases, with all tissues swelling radially. Swelling is accompanied by ectopic cell production but swelling is not reduced when the extra cell production is eliminated chemically. A double mutant was generated, whose roots swell constitutively and more than either parent. Based on analytical determination of acid-insoluble glucose, the amount of cellulose was normal in rsw4 and slightly elevated in rsw7. The orientation of cortical microtubules was examined with immunofluorescence in whole mounts and in semi-thin plastic sections, and the orientation of microfibrils was examined with field-emission scanning electron microscopy and quantitative polarized-light microscopy. In the swollen regions of both mutants, cortical microtubules and cellulose microfibrils are neither depleted nor disoriented. Thus, oriented microtubules and microfibrils themselves are insufficient to limit radial expansion; to build a wall with high mechanical anisotropy, additional factors are required, supplied in part by RSW4 and RSW7.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase1[OPEN

PubMed Central

Purushotham, Pallinti; Fang, Chao; Maranas, Cassandra; Bulone, Vincent

2017-01-01

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual β-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens. Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize β-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins. PMID:28768815

Pentagalloyl glucose increases elastin deposition, decreases reactive oxygen species and matrix metalloproteinase activity in pulmonary fibroblasts under inflammatory conditions.

PubMed

Parasaram, Vaideesh; Nosoudi, Nasim; Chowdhury, Aniqa; Vyavahare, Naren

2018-04-30

Emphysema is characterized by degradation of lung alveoli that leads to poor airflow in lungs. Irreversible elastic fiber degradation by matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) activity leads to loss of elasticity and drives the progression of this disease. We investigated if a polyphenol, pentagalloyl glucose (PGG) can increase elastin production in pulmonary fibroblasts. We also studied the effect of PGG treatment in reducing MMP activity and ROS levels in cells. We exposed rat pulmonary fibroblasts to two different types of inflammatory environments i.e., tumor necrosis factor-α (TNF-α) and cigarette smoke extract (CSE) to mimic the disease. Parameters like lysyl oxidase (LOX) and elastin gene expression, MMP-9 activity in the medium, lysyl oxidase (LOX) activity and ROS levels were studied to assess the effect of PGG on pulmonary fibroblasts. CSE inhibited lysyl oxidase (LOX) enzyme activity that resulted in a decreased elastin formation. Similarly, TNF-α treated cells showed less elastin in the cell layers. Both these agents caused increase in MMP activity and ROS levels in cells. However, when supplemented with PGG treatment along with these two inflammatory agents, we saw a significant increase in elastin deposition, reduction in both MMP activity and ROS levels. Thus PGG, which has anti-inflammatory, anti-oxidant properties coupled with its ability to aid in elastic fiber formation, can be a multifunctional drug to potentially arrest the progression of emphysema. Copyright © 2018 Elsevier Inc. All rights reserved.

Surface Plasmon Resonance Imaging of the Enzymatic Degradation of Cellulose Microfibrils

NASA Astrophysics Data System (ADS)

Reiter, Kyle; Raegen, Adam; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2012-02-01

As the largest component of biomass on Earth, cellulose represents a significant potential energy reservoir. Enzymatic hydrolysis of cellulose into fermentable sugars, an integral step in the production of biofuel, is a challenging problem on an industrial scale. More efficient conversion processes may be developed by an increased understanding of the action of the cellulolytic enzymes involved in cellulose degradation. We have used our recently developed quantitative, angle-scanning surface plasmon resonance imaging (SPRi) device to study the degradation of cellulose microfibrils upon exposure to cellulosic enzymes. In particular, we have studied the action of individual enzymes, and combinations of enzymes, from the Hypocrea Jecorina cellulase system on heterogeneous, industrially-relevant cellulose substrates. This has allowed us to define a characteristic time of action for the enzymes for different degrees of surface coverage of the cellulose microfibrils.

Variation in Loblolly pine cross-sectional microfibril angle with tree height and physiographic region

Treesearch

Lewis Jordon; Rechum Re; Daniel B. Hall; Alexander Clark; Richard F. Daniels

2006-01-01

The effect of height and physiographic region on whole disk cross-sectional microfibril angle (CSMFA) in loblolly pine (Pinus raeda L.) in the southern United States was evaluated. Whole disk CSMFA was determined at 1.4, 4.6, 7.6, 10.7, and 13.7 m up the stem of 59 trees, representing five physiographic regions. A mixed-effects analysis of variance was performed to...

Helicoidal Organization of Chitin in the Cuticle of the Migratory Locust Requires the Function of the Chitin Deacetylase2 Enzyme (LmCDA2)*

PubMed Central

Yu, Rongrong; Liu, Weimin; Li, Daqi; Zhao, Xiaoming; Ding, Guowei; Zhang, Min; Ma, Enbo; Zhu, KunYan; Li, Sheng; Moussian, Bernard; Zhang, Jianzhen

2016-01-01

In the three-dimensional extracellular matrix of the insect cuticle, horizontally aligned microfibrils composed of the polysaccharide chitin and associated proteins are stacked either parallel to each other or helicoidally. The underlying molecular mechanisms that implement differential chitin organization are largely unknown. To learn more about cuticle organization, we sought to study the role of chitin deacetylases (CDA) in this process. In the body cuticle of nymphs of the migratory locust Locusta migratoria, helicoidal chitin organization is changed to an organization with unidirectional microfibril orientation when LmCDA2 expression is knocked down by RNA interference. In addition, the LmCDA2-deficient cuticle is less compact suggesting that LmCDA2 is needed for chitin packaging. Animals with reduced LmCDA2 activity die at molting, underlining that correct chitin organization is essential for survival. Interestingly, we find that LmCDA2 localizes only to the initially produced chitin microfibrils that constitute the apical site of the chitin stack. Based on our data, we hypothesize that LmCDA2-mediated chitin deacetylation at the beginning of chitin production is a decisive reaction that triggers helicoidal arrangement of subsequently assembled chitin-protein microfibrils. PMID:27637332

Helicoidal Organization of Chitin in the Cuticle of the Migratory Locust Requires the Function of the Chitin Deacetylase2 Enzyme (LmCDA2).

PubMed

Yu, Rongrong; Liu, Weimin; Li, Daqi; Zhao, Xiaoming; Ding, Guowei; Zhang, Min; Ma, Enbo; Zhu, KunYan; Li, Sheng; Moussian, Bernard; Zhang, Jianzhen

2016-11-18

In the three-dimensional extracellular matrix of the insect cuticle, horizontally aligned microfibrils composed of the polysaccharide chitin and associated proteins are stacked either parallel to each other or helicoidally. The underlying molecular mechanisms that implement differential chitin organization are largely unknown. To learn more about cuticle organization, we sought to study the role of chitin deacetylases (CDA) in this process. In the body cuticle of nymphs of the migratory locust Locusta migratoria, helicoidal chitin organization is changed to an organization with unidirectional microfibril orientation when LmCDA2 expression is knocked down by RNA interference. In addition, the LmCDA2-deficient cuticle is less compact suggesting that LmCDA2 is needed for chitin packaging. Animals with reduced LmCDA2 activity die at molting, underlining that correct chitin organization is essential for survival. Interestingly, we find that LmCDA2 localizes only to the initially produced chitin microfibrils that constitute the apical site of the chitin stack. Based on our data, we hypothesize that LmCDA2-mediated chitin deacetylation at the beginning of chitin production is a decisive reaction that triggers helicoidal arrangement of subsequently assembled chitin-protein microfibrils. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Small Artery Elastin Distribution and Architecture-Focus on Three Dimensional Organization.

PubMed

Hill, Michael A; Nourian, Zahra; Ho, I-Lin; Clifford, Philip S; Martinez-Lemus, Luis; Meininger, Gerald A

2016-11-01

The distribution of ECM proteins within the walls of resistance vessels is complex both in variety of proteins and structural arrangement. In particular, elastin exists as discrete fibers varying in orientation across the adventitia and media as well as often resembling a sheet-like structure in the case of the IEL. Adding to the complexity is the tissue heterogeneity that exists in these structural arrangements. For example, small intracranial cerebral arteries lack adventitial elastin while similar sized arteries from skeletal muscle and intestinal mesentery exhibit a complex adventitial network of elastin fibers. With regard to the IEL, several vascular beds exhibit an elastin sheet with punctate holes/fenestrae while in others the IEL is discontinuous and fibrous in appearance. Importantly, these structural patterns likely sub-serve specific functional properties, including mechanosensing, control of external forces, mechanical properties of the vascular wall, cellular positioning, and communication between cells. Of further significance, these processes are altered in vascular disorders such as hypertension and diabetes mellitus where there is modification of ECM. This brief report focuses on the three-dimensional wall structure of small arteries and considers possible implications with regard to mechanosensing under physiological and pathophysiological conditions. © 2016 John Wiley & Sons Ltd.

Deposition of insoluble elastin by pulmonary fibroblasts from patients with COPD is increased by treatment with versican siRNA.

PubMed

Wu, Lian; Zhang, Jing; Qu, Jie Ming; Bai, Chun-Xue; Merrilees, Mervyn J

2017-01-01

A reduced content of alveolar elastic fibers is a key feature of COPD lung. Despite continued elastogenic potential by alveolar fibroblasts in the lung affected by COPD, repair of elastic fibers does not take place, which is due to increased levels of the chondroitin sulfate proteoglycan versican that inhibits the assembly of tropoelastin into fibers. In this study, primary pulmonary fibroblast cell lines from COPD and non-COPD patients were treated with a small interfering RNA (siRNA) against versican to determine if knockdown of versican could restore the deposition of insoluble elastin. Versican siRNA treatment reduced versican expression and secretion by pulmonary fibroblasts from both COPD and non-COPD patients ( P <0.01) and significantly increased deposition of insoluble elastin in the COPD cell cultures ( P <0.05). The treatment, however, did not significantly affect production of soluble elastin (tropoelastin) in either the COPD or non-COPD cell cultures, supporting a role for versican in inhibiting assembly but not synthesis of tropoelastin. These results suggest that removal or knockdown of versican may be a possible therapeutic strategy for increasing deposition of insoluble elastin and stimulating repair of elastic fibers in COPD lung.

Processing and characterization of α-elastin electrospun membranes

NASA Astrophysics Data System (ADS)

Araujo, J.; Padrão, J.; Silva, J. P.; Dourado, F.; Correia, D. M.; Botelho, G.; Gomez Ribelles, J. L.; Lanceros-Méndez, S.; Sencadas, V.

2014-06-01

Elastin isolated from fresh bovine ligaments was dissolved in a mixture of 1,1,1,3,3,3-Hexafluoro-2-propanol and water were electrospun into fiber membranes under different processing conditions. Fiber mats of randomly and aligned fibers were obtained with fixed and rotating ground collectors and fibrils were composed by thin ribbons whose width depends on electrospinning conditions; fibrils with 721 nm up to 2.12 μm width were achieved. After cross-linking with glutaraldehyde, α-elastin can uptake as much as 1700 % of PBS solution and a slight increase on fiber thickness was observed. The glass transition temperature of electrospun fiber mats was found to occur at ˜80 °C. Moreover, α-Elastin showed to be a perfect elastomeric material, and no mechanical hysteresis was found in cycle mechanical measurements. The elastic modulus obtained for random and aligned fibers mats in a PBS solution was 330±10 kPa and 732±165 kPa, respectively. Finally, the electrospinning and cross-linking process does not inhibit MC-3T3-E1 cell adhesion. Cell culture results showed good cell adhesion and proliferation in the cross-linked elastin fiber mats.

Hydroxyapatite and Calcified Elastin Induce Osteoblast-like Differentiation in Rat Aortic Smooth Muscle Cells

PubMed Central

Lei, Yang; Sinha, Aditi; Nosoudi, Nasim; Grover, Ankit; Vyavahare, Naren

2014-01-01

Vascular calcification can be categorized into two different types. Intimal calcification related to atherosclerosis and elastin-specific medial arterial calcification (MAC). Osteoblast-like differentiation of vascular smooth muscle cells (VSMCs) has been shown in both types; however, how this relates to initiation of vascular calcification is unclear. We hypothesize that the initial deposition of hydroxyapatite-like mineral in MAC occurs on degraded elastin first and that causes osteogenic transformation of VSMCs. To test this, rat aortic smooth muscle cells (RASMCs) were cultured on hydroxyapatite crystals and calcified aortic elastin. Using RT-PCR and specific protein assays, we demonstrate that RASMCs lose their smooth muscle lineage markers like alpha smooth muscle actin (SMA) and myosin heavy chain (MHC) and undergo chondrogenic/osteogenic transformation. This is indicated by an increase in the expression of typical chondrogenic proteins such as aggrecan, collagen type II alpha 1(Col2a1) and bone proteins such as runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN). Furthermore, when calcified conditions are removed, cells return to their original phenotype. Our data supports the hypothesis that elastin degradation and calcification precedes VSMCs' osteoblast-like differentiation. PMID:24447384

Williams-Beuren syndrome: phenotypic variability and deletions of chromosomes 7, 11, and 22 in a series of 52 patients.

PubMed Central

Joyce, C A; Zorich, B; Pike, S J; Barber, J C; Dennis, N R

1996-01-01

Fluorescence in situ hybridisation (FISH) and conventional chromosome analysis were performed on a series of 52 patients with classical Williams-Beuren syndrome (WBS), suspected WBS, or supravalvular aortic stenosis (SVAS). In the classical WBS group, 22/23 (96%) had a submicroscopic deletion of the elastin locus on chromosome 7, but the remaining patient had a unique interstitial deletion of chromosome 11 (del(11)(q13.5q14.2)). In the suspected WBS group 2/22 (9%) patients had elastin deletions but a third patient had a complex karyotype including a ring chromosome 22 with a deletion of the long arm (r(22)(p11-->q13)). In the SVAS group, 1/7 (14%) had an elastin gene deletion, despite having normal development and minimal signs of WBS. Overall, some patients with submicroscopic elastin deletions have fewer features of Williams-Beuren syndrome than those with other cytogenetic abnormalities. These results, therefore, emphasise the importance of a combined conventional and molecular cytogenetic approach to diagnosis and suggest that the degree to which submicroscopic deletions of chromosome 7 extend beyond the elastin locus may explain some of the phenotypic variability found in Williams-Beuren syndrome. Images PMID:9004128

Heparin Stimulates Elastogenesis: Application to Silk-Based Vascular Grafts

PubMed Central

Baughman, Cassandra; Kaplan, David L.; Castellot, John J.

2013-01-01

With over 500,000 coronary artery bypass grafts (CABG) performed annually in the United States alone, there is a significant clinical need for a small diameter tissue engineered vascular graft. A principle goal in tissue engineering is to develop materials and growth conditions that encourage appropriate re-cellularization and extracellular matrix formation in vivo. A particular challenge in vascular tissue engineering results from the inability of adult cells to produce elastin, as its expression is developmentally limited. We investigated factors to stimulate elastogenesis in vitro, and found that heparin treatment of adult human vascular smooth muscle cells promoted the formation of elastic fibers. This effect was heparin-specific, and dependent on cell density and growth state. We then applied this information to a silk-based construct, and found that immobilized heparin showed essentially identical biological effects to that of soluble heparin. These findings indicate that heparinized vascular grafts may promote elastin formation and regulate restenosis, in addition to heparin’s well-established antithrombotic properties. Given the increase in elastin mRNA level and the increase in extracellular elastin present, our data suggests that there may be multiple levels of elastin regulation that are mediated by heparin treatment. PMID:21600981

Inhibition of microRNA-29 enhances elastin levels in cells haploinsufficient for elastin and in bioengineered vessels--brief report.

PubMed

Zhang, Pei; Huang, Angela; Ferruzzi, Jacopo; Mecham, Robert P; Starcher, Barry C; Tellides, George; Humphrey, Jay D; Giordano, Frank J; Niklason, Laura E; Sessa, William C

2012-03-01

The goal of this study was to determine whether antagonizing microRNA (miR)-29 enhances elastin (ELN) levels in cells and tissues lacking ELN. miR-29 mimics reduced ELN levels in fibroblasts and smooth muscle cells, whereas miR-29 inhibition increased ELN levels. Antagonism of miR-29 also increased ELN levels in cells from patients haploinsufficient for ELN and in bioengineered human vessels. miR-29 antagonism may promote increased ELN levels during conditions of ELN deficiencies.

Col-F, a fluorescent probe for ex vivo confocal imaging of collagen and elastin in animal tissues.

PubMed

Biela, Ewa; Galas, Jerzy; Lee, Brian; Johnson, Gary L; Darzynkiewicz, Zbigniew; Dobrucki, Jurek W

2013-06-01

A new low-molecular-weight fluorescent probe, Col-F, that exhibits affinity to collagen and elastin, was used successfully in imaging of extracellular matrix in freshly excised animal tissues. Col-F readily penetrates between live cells into tissues and binds to fibers of collagen and elastin by a noncovalent mechanism. Fibers of collagen and elastin have been stained in a variety of tissues, including tendon, skeletal muscle, connective tissue, and arteries. Cells migrating in a Col-F-stained collagenous biomaterial were also imaged. No phototoxic effects were detected when live keratocytes were imaged in the in vitro culture in the presence of Col-F. In conclusion, Col-F provides a simple and convenient tool for fluorescence three-dimensional imaging of intricate collagenous and elastic structures in live and fixed animal tissues, as well as in collagen-containing biomaterials. Copyright © 2013 International Society for Advancement of Cytometry.

Morphological variation of stimuli-responsive polypeptide at air-water interface

NASA Astrophysics Data System (ADS)

Shin, Sungchul; Ahn, Sungmin; Cheng, Jie; Chang, Hyejin; Jung, Dae-Hong; Hyun, Jinho

2016-12-01

The morphological variation of stimuli-responsive polypeptide molecules at the air-water interface as a function of temperature and compression was described. The surface pressure-area (π-A) isotherms of an elastin-like polypeptide (ELP) monolayer were obtained under variable external conditions, and Langmuir-Blodgett (LB) monolayers were deposited onto a mica substrate for characterization. As the compression of the ELP monolayer increased, the surface pressure increased gradually, indicating that the ELP monolayer could be prepared with high stability at the air-water interface. The temperature in the subphase of the ELP monolayer was critical in the preparation of LB monolayers. The change in temperature induced a shift in the π-A isotherms as well as a change in ELP secondary structures. Surprisingly, the compression of the ELP monolayer influenced the ELP secondary structure due to the reduction in the phase transition temperature with decreasing temperature. The change in the ELP secondary structure formed at the air-water interface was investigated by surface-enhanced Raman scattering. Moreover, the morphology of the ELP monolayer was subsequently imaged using atomic force microscopy. The temperature responsive behavior resulted in changes in surface morphology from relatively flat structures to rugged labyrinth structures, which suggested conformational changes in the ELP monolayers.

Concerns about a variance approach to X-ray diffractometric estimation of microfibril angle in wood

Treesearch

Steve P. Verrill; David E. Kretschmann; Victoria L. Herian; Michael C. Wiemann; Harry A. Alden

2011-01-01

In this article, we raise three technical concerns about Evans’ 1999 Appita Journal “variance approach” to estimating microfibril angle (MFA). The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the MFA and the natural variability of the MFA. The second concern is associated with the approximation...

Multivariate modeling of acoustomechanical response of 14-year-old suppressed loblolly pine (Pinus taeda) to variation in wood chemistry, microfibril angle and density

Treesearch

Charles Essien; Brian K. Via; Qingzheng Cheng; Thomas Gallagher; Timothy McDonald; Xiping Wang; Lori G. Eckhardt

2017-01-01

The polymeric angle and concentration within the S2 layer of the softwood fiber cell wall are very critical for molecular and microscopic properties that influence strength, stiffness and acoustic velocity of wood at the macroscopic level. The main objective of this study was to elucidate the effect of cellulose, hemicellulose, lignin, microfibril angle and density on...

Versatile gas-phase reactions for surface to bulk esterification of cellulose microfibrils aerogels.

PubMed

Fumagalli, Matthieu; Ouhab, Djamila; Boisseau, Sonia Molina; Heux, Laurent

2013-09-09

Aqueous suspensions of microfibrillated cellulose obtained by a high pressure homogenization process were freeze-dried after solvent exchange into tert-butanol. The resulting aerogels, which displayed a remarkable open morphology with a surface area reaching 100 m(2)/g, were subjected to a gas-phase esterification with palmitoyl chloride. Under these conditions, variations of the reaction temperature from 100 to 200 °C, of the reaction time from 0.5 to 2 h, and of the initial quantity of reagent, led to the preparation of a library of cellulose palmitates with DS varying from zero to 2.36. These products were characterized by gravimetry, FTIR, and (13)C solid-state NMR spectroscopy. Of special interest were the cellulose palmitate samples of low DS in the range of 0.1-0.4, which corresponded to hydrophobic cellulose microfibrils exclusively esterified at their surface while keeping intact their inner structure.

Periodic disorder along ramie cellulose microfibrils.

PubMed

Nishiyama, Yoshiharu; Kim, Ung-Jin; Kim, Dae-Young; Katsumata, Kyoko S; May, Roland P; Langan, Paul

2003-01-01

Small angle neutron scattering studies have been carried out on cellulose fibers from ramie and Populus maximowicii (cotton wood). Labile hydrogen atoms were replaced by deuterium atoms, in water-accessible disordered regions of the fibers, to increase the neutron scattering contrast between the disordered and crystalline regions. A meridional Bragg reflection, corresponding to a longitudinal periodicity of 150 nm, was observed when scattering collected from hydrogenated and deuterated dry ramie fibers was subtracted. No Bragg reflection was observed with the cotton wood fibers, probably because of lower orientation of the microfibrils in the cell wall. The ramie fibers were then subjected to electron microscopy, acid hydrolysis, gel permeation chromatography, and viscosity studies. The leveling off degree of polymerization (LODP) of the hydrolyzed samples matched exactly the periodicity observed in the diffraction studies. The weight loss related to the LODP was only about 1.5%, and thus, the microfibrils can be considered to have 4-5 disordered residues every 300 residues.

Cellulose fibres, nanofibrils and microfibrils: The morphological sequence of MFC components from a plant physiology and fibre technology point of view

NASA Astrophysics Data System (ADS)

Chinga-Carrasco, Gary

2011-06-01

During the last decade, major efforts have been made to develop adequate and commercially viable processes for disintegrating cellulose fibres into their structural components. Homogenisation of cellulose fibres has been one of the principal applied procedures. Homogenisation has produced materials which may be inhomogeneous, containing fibres, fibres fragments, fibrillar fines and nanofibrils. The material has been denominated microfibrillated cellulose (MFC). In addition, terms relating to the nano-scale have been given to the MFC material. Several modern and high-tech nano-applications have been envisaged for MFC. However, is MFC a nano-structure? It is concluded that MFC materials may be composed of (1) nanofibrils, (2) fibrillar fines, (3) fibre fragments and (4) fibres. This implies that MFC is not necessarily synonymous with nanofibrils, microfibrils or any other cellulose nano-structure. However, properly produced MFC materials contain nano-structures as a main component, i.e. nanofibrils.

Influence of elastin-derived peptides, glucose, LDL and oxLDL on nitric oxide synthase expression in human umbilical artery endothelial cells.

PubMed

Garczorz, Wojciech; Francuz, Tomasz; Gmiński, Jan; Likus, Wirginia; Siemianowicz, Krzysztof; Jurczak, Teresa; Strzałka-Mrozik, Barbara

2011-01-01

Endothelial dysfunction plays an important role in the development of atherosclerosis. Elastin-derived peptides (EDP), hyperglycemia, hypercholesterolemia and oxidized LDL have a proven proatherosclerotic potential. Nitric oxide generated by endothelial nitric oxide synthase (eNOS; EC 1.14.13.39) is an important vasorelaxant. Here we studied the influence of those proatherosclerotic factors on eNOS gene and protein expression in artery-derived endothelial cells. Human umbilical artery endothelial cells (HUAEC) were incubated with or without: glucose (270 mg/dl), LDL (200 mg/dl), oxidized LDL (oxLDL 25 mg/dl) or κ-elastin (0.5 and 2.5 µg/ml). Gene expression was assessed by real time RT-PCR, whilst the eNOS protein by ELISA. In cells incubated with 2.5 µg/ml of κ-elastin, a 31 % increase of eNOS mRNA expression was observed, but the protein level remained unchanged. OxLDL, LDL and glucose decreased the eNOS protein level by 74 %, 37 % and 29 %, respectively. OxLDL decreased eNOS mRNA by 42 %. LDL non-significantly decreased eNOS mRNA expression. An elevated glucose level did not affect the eNOS mRNA expression. Hyperglycemia and an elevated level of LDL, particularly oxLDL, decreased the level of eNOS protein in endothelial cells. As κ-elastin did not decrease the expression of eNOS gene in HUAEC, the proatherogenic properties of elastin-derived peptides are unlikely to be due to their influence on eNOS.

Chronic Treatment with Minoxidil Induces Elastic Fiber Neosynthesis and Functional Improvement in the Aorta of Aged Mice.

PubMed

Coquand-Gandit, Marion; Jacob, Marie-Paule; Fhayli, Wassim; Romero, Beatriz; Georgieva, Miglena; Bouillot, Stéphanie; Estève, Eric; Andrieu, Jean-Pierre; Brasseur, Sandrine; Bouyon, Sophie; Garcia-Honduvilla, Natalio; Huber, Philippe; Buján, Julia; Atanasova, Milena; Faury, Gilles

2017-06-01

Normal arterial aging processes involve vascular cell dysfunction associated with wall stiffening, the latter being due to progressive elastin and elastic fiber degradation, and elastin and collagen cross-linking by advanced glycation end products (AGEs). These processes progressively lead to cardiovascular dysfunction during aging. Elastin is only synthesized during late gestation and childhood, and further degradation occurring throughout adulthood cannot be physiologically compensated by replacement of altered material. However, the ATP-dependent K + channel opener minoxidil has been shown to stimulate elastin expression in vitro and in vivo in the aorta of young adult rats. Therefore, we have studied the effect of a 10-week chronic oral treatment with minoxidil (120 mg/L in drinking water) on the aortic structure and function in aged 24-month-old mice. Minoxidil treatment increased tropoelastin, fibulin-5, and lysyl-oxidase messenger RNA levels, reinduced a moderate expression of elastin, and lowered the levels of AGE-related molecules. This was accompanied by the formation of newly synthesized elastic fibers, which had diverse orientations in the wall. A decrease in the glycation capacity of aortic elastin was also produced by minoxidil treatment. The ascending aorta also underwent a minoxidil-induced increase in diameter and decrease in wall thickness, which partly reversed the age-associated thickening and returned the wall thickness value and strain-stress relation closer to those of younger adult animals. In conclusion, our results suggest that minoxidil presents an interesting potential for arterial remodeling in an antiaging perspective, even when treating already aged animals.

Computational smart polymer design based on elastin protein mutability.

PubMed

Tarakanova, Anna; Huang, Wenwen; Weiss, Anthony S; Kaplan, David L; Buehler, Markus J

2017-05-01

Soluble elastin-like peptides (ELPs) can be engineered into a range of physical forms, from hydrogels and scaffolds to fibers and artificial tissues, finding numerous applications in medicine and engineering as "smart polymers". Elastin-like peptides are attractive candidates as a platform for novel biomaterial design because they exhibit a highly tunable response spectrum, with reversible phase transition capabilities. Here, we report the design of the first virtual library of elastin-like protein models using methods for enhanced sampling to study the effect of peptide chemistry, chain length, and salt concentration on the structural transitions of ELPs, exposing associated molecular mechanisms. We describe the behavior of the local molecular structure under increasing temperatures and the effect of peptide interactions with nearest hydration shell water molecules on peptide mobility and propensity to exhibit structural transitions. Shifts in the magnitude of structural transitions at the single-molecule scale are explained from the perspective of peptide-ion-water interactions in a library of four unique elastin-like peptide systems. Predictions of structural transitions are subsequently validated in experiment. This library is a valuable resource for recombinant protein design and synthesis as it elucidates mechanisms at the single-molecule level, paving a feedback path between simulation and experiment for smart material designs, with applications in biomedicine and diagnostic devices. Copyright © 2017. Published by Elsevier Ltd.

MicroRNA-29 facilitates transplantation of bone marrow-derived mesenchymal stem cells to alleviate pelvic floor dysfunction by repressing elastin.

PubMed

Jin, Minfei; Wu, Yuelin; Wang, Jun; Ye, Weiping; Wang, Lei; Yin, Peipei; Liu, Wei; Pan, Chenhao; Hua, Xiaolin

2016-11-17

Pelvic floor dysfunction (PFD) is a condition affecting many women worldwide, with symptoms including stress urinary incontinence (SUI) and pelvic organ prolapse (POP). We have previously demonstrated stable elastin-expressing bone marrow-derived mesenchymal stem cells (BMSCs) attenuated PFD in rats, and aim to further study the effect of microRNA-29a-3p regulation on elastin expression and efficacy of BMSC transplantation therapy. We inhibited endogenous microRNA-29a-3p in BMSCs and investigated its effect on elastin expression by RT-PCR and Western blot. MicroRNA-29-inhibited BMSCs were then transplanted into PFD rats, accompanied by sustained release of bFGF using formulated bFGF in poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NP), followed by evaluation of urodynamic tests. MicroRNA-29a-3p inhibition resulted in upregulated expression and secretion of elastin in in vitro culture of BMSCs. After co-injection with PLGA-loaded bFGF NP into the PFD rats in vivo, microRNA-29a-3p-inhibited BMSCs significantly improved the urodynamic test results. Our multidisciplinary study, combining microRNA biology, genetically engineered BMSCs, and nanoparticle technology, provides an excellent stem cell-based therapy for repairing connective tissues and treating PFD.

Clusterin associates with altered elastic fibers in human photoaged skin and prevents elastin from ultraviolet-induced aggregation in vitro.

PubMed

Janig, Elke; Haslbeck, Martin; Aigelsreiter, Ariane; Braun, Nathalie; Unterthor, Daniela; Wolf, Peter; Khaskhely, Noor M; Buchner, Johannes; Denk, Helmut; Zatloukal, Kurt

2007-11-01

Clusterin is a secreted glycoprotein with stress-induced expression in various diseased and aged tissues. It shares basic features with small heat shock proteins because it may stabilize proteins in a folding-competent state. Besides its presence in all human body fluids, clusterin associates with altered extracellular matrix proteins, such as beta-amyloid in Alzheimer senile plaques in the brain. Because dermal connective tissue alterations occur because of aging and UV radiation, we explored the occurrence of clusterin in young, aged, and sun-exposed human skin. Immunohistochemical analysis showed that clusterin is constantly associated with altered elastic fibers in aged human skin. Elastotic material of sun-damaged skin (solar elastosis), in particular, revealed a strong staining for clusterin. Because of the striking co-localization of clusterin with abnormal elastic material, we investigated the interaction of clusterin with elastin in vitro. A chaperone assay was established in which elastin was denatured by UV irradiation in the absence or presence of clusterin. This assay demonstrated that clusterin exerted a chaperone-like activity and effectively inhibited UV-induced aggregation of elastin. The interaction of both proteins was further analyzed by electron microscopy, size exclusion chromatography, and mass spectrometry, in which clusterin was found in a stable complex with elastin after UV exposure.

Clusterin Associates with Altered Elastic Fibers in Human Photoaged Skin and Prevents Elastin from Ultraviolet-Induced Aggregation in Vitro

PubMed Central

Janig, Elke; Haslbeck, Martin; Aigelsreiter, Ariane; Braun, Nathalie; Unterthor, Daniela; Wolf, Peter; Khaskhely, Noor M.; Buchner, Johannes; Denk, Helmut; Zatloukal, Kurt

2007-01-01

Clusterin is a secreted glycoprotein with stress-induced expression in various diseased and aged tissues. It shares basic features with small heat shock proteins because it may stabilize proteins in a folding-competent state. Besides its presence in all human body fluids, clusterin associates with altered extracellular matrix proteins, such as β-amyloid in Alzheimer senile plaques in the brain. Because dermal connective tissue alterations occur because of aging and UV radiation, we explored the occurrence of clusterin in young, aged, and sun-exposed human skin. Immunohistochemical analysis showed that clusterin is constantly associated with altered elastic fibers in aged human skin. Elastotic material of sun-damaged skin (solar elastosis), in particular, revealed a strong staining for clusterin. Because of the striking co-localization of clusterin with abnormal elastic material, we investigated the interaction of clusterin with elastin in vitro. A chaperone assay was established in which elastin was denatured by UV irradiation in the absence or presence of clusterin. This assay demonstrated that clusterin exerted a chaperone-like activity and effectively inhibited UV-induced aggregation of elastin. The interaction of both proteins was further analyzed by electron microscopy, size exclusion chromatography, and mass spectrometry, in which clusterin was found in a stable complex with elastin after UV exposure. PMID:17872975

Elastin: a representative ideal protein elastomer.

PubMed Central

Urry, D W; Hugel, T; Seitz, M; Gaub, H E; Sheiba, L; Dea, J; Xu, J; Parker, T

2002-01-01

During the last half century, identification of an ideal (predominantly entropic) protein elastomer was generally thought to require that the ideal protein elastomer be a random chain network. Here, we report two new sets of data and review previous data. The first set of new data utilizes atomic force microscopy to report single-chain force-extension curves for (GVGVP)(251) and (GVGIP)(260), and provides evidence for single-chain ideal elasticity. The second class of new data provides a direct contrast between low-frequency sound absorption (0.1-10 kHz) exhibited by random-chain network elastomers and by elastin protein-based polymers. Earlier composition, dielectric relaxation (1-1000 MHz), thermoelasticity, molecular mechanics and dynamics calculations and thermodynamic and statistical mechanical analyses are presented, that combine with the new data to contrast with random-chain network rubbers and to detail the presence of regular non-random structural elements of the elastin-based systems that lose entropic elastomeric force upon thermal denaturation. The data and analyses affirm an earlier contrary argument that components of elastin, the elastic protein of the mammalian elastic fibre, and purified elastin fibre itself contain dynamic, non-random, regularly repeating structures that exhibit dominantly entropic elasticity by means of a damping of internal chain dynamics on extension. PMID:11911774

Complementary effects of multi-protein components on biomineralization in vitro

PubMed Central

Ba, Xiaolan; Rafailovich, Miriam; Meng, Yizhi; Pernodet, Nadine; Wirick, Sue; Füredi-Milhofer, Helga; Qin, Yi-Xian; DiMasi, Elaine

2016-01-01

The extracellular matrix (ECM) is composed of mixed protein fibers whose precise composition affects biomineralization. New methods are needed to probe the interactions of these proteins with calcium phosphate mineral and with each other. Here we follow calcium phosphate mineralization on protein fibers self-assembled in vitro from solutions of fibronectin, elastin and their mixture. We probe the surface morphology and mechanical properties of the protein fibers during the early stages. The development of mineral crystals on the protein matrices is also investigated. In physiological mineralization solution, the elastic modulus of the fibers in the fibronectin-elastin mixture increases to a greater extent than that of the fibers from either pure protein. In the presence of fibronectin, longer exposure in the mineral solution leads to the formation of amorphous calcium phosphate particles templated along the self-assembled fibers, while elastin fibers only collect calcium without any mineral observed during early stage. TEM images confirm that small needle-shape crystals are confined inside elastin fibers which suppress the release of mineral outside the fibers during late stage, while hydroxyapatite crystals form when fibronectin is present. These results demonstrate complementary actions of the two ECM proteins fibronectin and elastin to collect cations and template mineral, respectively. PMID:20035875

Juvenile/mature wood transition in loblolly pine as defined by annual ring specific gravity, proportion of latewood, and microfibril angle

Treesearch

Alexander Clark; Richard F. Daniels; Lewis Jordan

2006-01-01

The length of juvenility or number of years a tree produces juvenile wood at a fixed height can be defined by the age of the wood at which properties change from juvenile to mature wood. This paper estimates the age of transition from juvenile to mature wood based on ring specific gravity (SG), proportion of annual ring in latewood, and ring average microfibril angle (...

Bratislava Symposium on Saccharides (7th) Programme and Abstracts

DTIC Science & Technology

1994-09-01

that of cellulose (1). Althoug the binding capacity of cellulose microfibrils is dependent on the sace of the binding un of the kmfbrul& xyloglucans...are not only party embedded in but are also parly free between microfibrils . suggesting cross-link to cellulose microfibuils (2). Xyloglucan...desediftcoli Y.-C.-M a 12. KoIlkovd B., Hricovfrni M., Sirmoutti R.: 43C NMR study of solid-stal, reaction of cellulose with lIgnin monomers 13. Joniak D

Study of Transport Properties and Structure of Extended-Chain Polymers: Diffusion and Solubility of Gases.

DTIC Science & Technology

1985-09-01

sonication of PPBT fibers .... .............. 123 53. (a) Proposed stacking forms of microfibrils with voids in intarval s .... .............. 124 (b... cellulose (Newns, 1956), Keratin (King, 1945) and -. inyl alcohol• 41 (Long and Thomoson, 1935). -The -water remaining inside PPBT in the deso-r-’tion...kinked ribbons is orcoosed n Figure (52) Each microfibril consists of a succession of narrow 0 crvstallites (50 x 500 A or smaller) enmbedded in

Chitinase-like1/pom-pom1 and its homolog CTL2 are glucan-interacting proteins important for cellulose biosynthesis in Arabidopsis.

PubMed

Sánchez-Rodríguez, Clara; Bauer, Stefan; Hématy, Kian; Saxe, Friederike; Ibáñez, Ana Belén; Vodermaier, Vera; Konlechner, Cornelia; Sampathkumar, Arun; Rüggeberg, Markus; Aichinger, Ernst; Neumetzler, Lutz; Burgert, Ingo; Somerville, Chris; Hauser, Marie-Theres; Persson, Staffan

2012-02-01

Plant cells are encased by a cellulose-containing wall that is essential for plant morphogenesis. Cellulose consists of β-1,4-linked glucan chains assembled into paracrystalline microfibrils that are synthesized by plasma membrane-located cellulose synthase (CESA) complexes. Associations with hemicelluloses are important for microfibril spacing and for maintaining cell wall tensile strength. Several components associated with cellulose synthesis have been identified; however, the biological functions for many of them remain elusive. We show that the chitinase-like (CTL) proteins, CTL1/POM1 and CTL2, are functionally equivalent, affect cellulose biosynthesis, and are likely to play a key role in establishing interactions between cellulose microfibrils and hemicelluloses. CTL1/POM1 coincided with CESAs in the endomembrane system and was secreted to the apoplast. The movement of CESAs was compromised in ctl1/pom1 mutant seedlings, and the cellulose content and xyloglucan structures were altered. X-ray analysis revealed reduced crystalline cellulose content in ctl1 ctl2 double mutants, suggesting that the CTLs cooperatively affect assembly of the glucan chains, which may affect interactions between hemicelluloses and cellulose. Consistent with this hypothesis, both CTLs bound glucan-based polymers in vitro. We propose that the apoplastic CTLs regulate cellulose assembly and interaction with hemicelluloses via binding to emerging cellulose microfibrils.

CHITINASE-LIKE1/POM-POM1 and Its Homolog CTL2 Are Glucan-Interacting Proteins Important for Cellulose Biosynthesis in Arabidopsis[W][OA

PubMed Central

Sánchez-Rodríguez, Clara; Bauer, Stefan; Hématy, Kian; Saxe, Friederike; Ibáñez, Ana Belén; Vodermaier, Vera; Konlechner, Cornelia; Sampathkumar, Arun; Rüggeberg, Markus; Aichinger, Ernst; Neumetzler, Lutz; Burgert, Ingo; Somerville, Chris; Hauser, Marie-Theres; Persson, Staffan

2012-01-01

Plant cells are encased by a cellulose-containing wall that is essential for plant morphogenesis. Cellulose consists of β-1,4-linked glucan chains assembled into paracrystalline microfibrils that are synthesized by plasma membrane–located cellulose synthase (CESA) complexes. Associations with hemicelluloses are important for microfibril spacing and for maintaining cell wall tensile strength. Several components associated with cellulose synthesis have been identified; however, the biological functions for many of them remain elusive. We show that the chitinase-like (CTL) proteins, CTL1/POM1 and CTL2, are functionally equivalent, affect cellulose biosynthesis, and are likely to play a key role in establishing interactions between cellulose microfibrils and hemicelluloses. CTL1/POM1 coincided with CESAs in the endomembrane system and was secreted to the apoplast. The movement of CESAs was compromised in ctl1/pom1 mutant seedlings, and the cellulose content and xyloglucan structures were altered. X-ray analysis revealed reduced crystalline cellulose content in ctl1 ctl2 double mutants, suggesting that the CTLs cooperatively affect assembly of the glucan chains, which may affect interactions between hemicelluloses and cellulose. Consistent with this hypothesis, both CTLs bound glucan-based polymers in vitro. We propose that the apoplastic CTLs regulate cellulose assembly and interaction with hemicelluloses via binding to emerging cellulose microfibrils. PMID:22327741

Cellulose structure and lignin distribution in normal and compression wood of the Maidenhair tree (Ginkgo biloba L.).

PubMed

Andersson, Seppo; Wang, Yurong; Pönni, Raili; Hänninen, Tuomas; Mononen, Marko; Ren, Haiqing; Serimaa, Ritva; Saranpää, Pekka

2015-04-01

We studied in detail the mean microfibril angle and the width of cellulose crystals from the pith to the bark of a 15-year-old Maidenhair tree (Ginkgo biloba L.). The orientation of cellulose microfibrils with respect to the cell axis and the width and length of cellulose crystallites were determined using X-ray diffraction. Raman microscopy was used to compare the lignin distribution in the cell wall of normal/opposite and compression wood, which was found near the pith. Ginkgo biloba showed a relatively large mean microfibril angle, varying between 19° and 39° in the S2 layer, and the average width of cellulose crystallites was 3.1-3.2 nm. Mild compression wood without any intercellular spaces or helical cavities was observed near the pith. Slit-like bordered pit openings and a heavily lignified S2L layer confirmed the presence of compression wood. Ginkgo biloba showed typical features present in the juvenile wood of conifers. The microfibril angle remained large over the 14 annual rings. The entire stem disc, with a diameter of 18 cm, was considered to consist of juvenile wood. The properties of juvenile and compression wood as well as the cellulose orientation and crystalline width indicate that the wood formation of G. biloba is similar to that of modern conifers. © 2015 Institute of Botany, Chinese Academy of Sciences.

Synthesis of elastic microfibrillar components fibrillin-1 and fibrillin-2 by human optic nerve head astrocytes in situ and in vitro.

PubMed

Pena, J D; Mello, P A; Hernandez, M R

2000-05-01

The purpose of this study was to identify elastic microfibrillar components fibrillin-1 and fibrillin-2 in optic nerve heads of adult normal and glaucomatous subjects, in cultured optic nerve head astrocytes (type 1B astrocytes), as well as fibrillin-1 in fetal optic nerve heads. To characterize synthesis and gene expression of microfibrillar proteins in human optic nerve heads and cultured type 1B astrocytes, light microscopy immunohistochemistry, in situ hybridization, and RT-PCR or Northern blots were performed. Our results demonstrated that fibrillin-1 was associated with blood vessels, astrocytes in the glial columns and cribriform plates, and with astrocyte processes in the nerve bundles in all samples. In glaucomatous optic nerves there was enhanced fibrillin-1 immunoreactivity, especially surrounding blood vessels. Fibrillin-2 was localized primarily to blood vessels in all samples, without qualitative differences between normal and glaucomatous samples. In fetal optic nerve heads fibrillin-1 mRNA was localized to glial cells and to the blood vessel walls. In adult optic nerve heads, there was little fibrillin-1 mRNA as detectable by in situ hybridization and RT-PCR. There was no detectable upregulation of fibrillin-1 mRNA in glaucoma. In cultured type 1B astrocytes, fibrillin-1 staining was mostly pericellular. There was little fibrillin-2 immunoreactivity. In conclusion, astrocytes from the optic nerve head deposit elastic microfibrillar components in situ and in vitro, with a predominance of fibrillin-1. Upregulation of fibrillin-1 mRNA was not observed in glaucoma, suggesting that increased transcription may occur early in the disease process. Cultures of type 1B astrocytes from the optic nerve head provides a useful model to study mechanisms regulating the interactions of elastin and the microfibrils in optic nerve head astrocytes.

Gene expression levels of elastin and fibulin-5 according to differences between carotid plaque regions.

PubMed

Sivrikoz, Emre; Timirci-Kahraman, Özlem; Ergen, Arzu; Zeybek, Ümit; Aksoy, Murat; Yanar, Fatih; İsbir, Turgay; Kurtoğlu, Mehmet

2015-01-01

The purpose of this study was to investigate the gene expression levels of elastin and fibulin-5 according to differences between carotid plaque regions and to correlate it with clinical features of plaque destabilization. The study included 44 endarterectomy specimens available from operated symptomatic carotid artery stenoses. The specimens were separated according to anatomic location: internal carotid artery (ICA), external carotid artery (ECA) and common carotid artery (CCA), and then stored in liquid nitrogen. The amounts of cDNA for elastin and fibulin-5 were determined by Quantitative real-time PCR (Q-RT-PCR). Target gene copy numbers were normalized using hypoxanthine-guanine phosphoribosyltransferase (HPRT1) gene. The delta-delta CT method was applied for relative quantification. Q-RT-PCR data showed that relative fibulin-5 gene expression was increased in ICA plaque regions when compared to CCA regions but not reaching significance (p=0.061). At the same time, no differences were observed in elastin mRNA level between different anatomic plaque regions (p>0.05). Moreover, elastin and fibulin-5 mRNA expression and clinical parameters were compared in ICA plaques versus CCA and ECA regions, respectively. Up-regulation of elastin and fibulin-5 mRNA levels in ICA were strongly correlated with family history of cardiovascular disease when compared to CCA (p<0.05). Up-regulation of fibulin-5 in ICA was significantly associated with diabetes, and elevated triglycerides and very low density lipoprotein (VLDL) when compared to ECA (p<0.05). The clinical significance is the differences between the proximal and distal regions of the lesion, associated with the ICA, CCA and ECA respectively, with increased fibulin-5 in the ICA region. Copyright © 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Lung matrix and vascular remodeling in mechanically ventilated elastin haploinsufficient newborn mice

PubMed Central

Hilgendorff, Anne; Parai, Kakoli; Ertsey, Robert; Navarro, Edwin; Jain, Noopur; Carandang, Francis; Peterson, Joanna; Mokres, Lucia; Milla, Carlos; Preuss, Stefanie; Alcazar, Miguel Alejandre; Khan, Suleman; Masumi, Juliet; Ferreira-Tojais, Nancy; Mujahid, Sana; Starcher, Barry; Rabinovitch, Marlene

2014-01-01

Elastin plays a pivotal role in lung development. We therefore queried if elastin haploinsufficient newborn mice (Eln+/−) would exhibit abnormal lung structure and function related to modified extracellular matrix (ECM) composition. Because mechanical ventilation (MV) has been linked to dysregulated elastic fiber formation in the newborn lung, we also asked if elastin haploinsufficiency would accentuate lung growth arrest seen after prolonged MV of neonatal mice. We studied 5-day-old wild-type (Eln+/+) and Eln+/− littermates at baseline and after MV with air for 8–24 h. Lungs of unventilated Eln+/− mice contained ∼50% less elastin and ∼100% more collagen-1 and lysyl oxidase compared with Eln+/+ pups. Eln+/− lungs contained fewer capillaries than Eln+/+ lungs, without discernible differences in alveolar structure. In response to MV, lung tropoelastin and elastase activity increased in Eln+/+ neonates, whereas tropoelastin decreased and elastase activity was unchanged in Eln+/− mice. Fibrillin-1 protein increased in lungs of both groups during MV, more in Eln+/− than in Eln+/+ pups. In both groups, MV caused capillary loss, with larger and fewer alveoli compared with unventilated controls. Respiratory system elastance, which was less in unventilated Eln+/− compared with Eln+/+ mice, was similar in both groups after MV. These results suggest that elastin haploinsufficiency adversely impacts pulmonary angiogenesis and that MV dysregulates elastic fiber integrity, with further loss of lung capillaries, lung growth arrest, and impaired respiratory function in both Eln+/+ and Eln+/− mice. Paucity of lung capillaries in Eln+/− newborns might help explain subsequent development of pulmonary hypertension previously reported in adult Eln+/− mice. PMID:25539853

Genetic Modifiers of Cardiovascular Phenotype Caused by Elastin Haploinsufficiency Act by Extrinsic Noncomplementation*

PubMed Central

Kozel, Beth A.; Knutsen, Russell H.; Ye, Li; Ciliberto, Christopher H.; Broekelmann, Thomas J.; Mecham, Robert P.

2011-01-01

Elastin haploinsufficiency causes the cardiovascular complications associated with Williams-Beuren syndrome and isolated supravalvular aortic stenosis. Significant variability exists in the vascular pathology in these individuals. Using the Eln+/− mouse, we sought to identify the source of this variability. Following outcrossing of C57Bl/6J Eln+/−, two backgrounds were identified whose cardiovascular parameters deviated significantly from the parental strain. F1 progeny of the C57Bl/6J; Eln+/−x129X1/SvJ were more hypertensive and their arteries less compliant. In contrast, Eln+/− animals crossed to DBA/2J were protected from the pathologic changes associated with elastin insufficiency. Among the crosses, aortic elastin and collagen content did not correlate with quantitative vasculopathy traits. Quantitative trait locus analysis performed on F2 C57; Eln+/−x129 intercrosses identified highly significant peaks on chromosome 1 (LOD 9.7) for systolic blood pressure and on chromosome 9 (LOD 8.7) for aortic diameter. Additional peaks were identified that affect only Eln+/−, including a region upstream of Eln on chromosome 5 (LOD 4.5). Bioinformatic analysis of the quantitative trait locus peaks revealed several interesting candidates, including Ren1, Ncf1, and Nos1; genes whose functions are unrelated to elastic fiber assembly, but whose effects may synergize with elastin insufficiency to predispose to hypertension and stiffer blood vessels. Real time RT-PCR studies show background-specific increased expression of Ncf1 (a subunit of the NOX2 NAPDH oxidase) that parallel the presence of increased oxidative stress in Eln+/− aortas. This finding raises the possibility that polymorphisms in genes affecting the generation of reactive oxygen species alter cardiovascular function in individuals with elastin haploinsufficiency through extrinsic noncomplementation. PMID:22049077

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

PubMed

Preil, Simone Andrea Rørdam; Thorsen, Anne-Sofie Faarvang; Christiansen, Anne Lindegaard; Poulsen, Mikael Kjær; Karsdal, Morten Asser; Leeming, Diana Julie; Rasmussen, Lars Melholt

2017-11-01

Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM. Blood samples from 302 type 2 diabetic patients were analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index. T2DM patients with peripheral arterial disease (low ankle-brachial index) (PAD) display higher levels of MMP-2 and ELM compared to patients without PAD. However, none of the proteins or degradation products correlated with myocardial ischemia or a combined measure of CVD-signs, including myocardial ischemia, increased carotid thickness and decreased ankle-brachial blood pressure. Our results suggest that the diabetic environment affects the circulating amounts of MMP-2 and ELM in patients with PAD. However, the same connection could not be seen in diabetic patients with CVD broadly identified in three vascular territories. LOX and ELM-2 did not correlate to any type of CVD. Overall, serum levels of elastin-related molecules are only remotely related to CVD in type 2 diabetes.

mTOR (Mechanistic Target of Rapamycin) Inhibition Decreases Mechanosignaling, Collagen Accumulation, and Stiffening of the Thoracic Aorta in Elastin-Deficient Mice.

PubMed

Jiao, Yang; Li, Guangxin; Li, Qingle; Ali, Rahmat; Qin, Lingfeng; Li, Wei; Qyang, Yibing; Greif, Daniel M; Geirsson, Arnar; Humphrey, Jay D; Tellides, George

2017-09-01

Elastin deficiency because of heterozygous loss of an ELN allele in Williams syndrome causes obstructive aortopathy characterized by medial thickening and fibrosis and consequent aortic stiffening. Previous work in Eln -null mice with a severe arterial phenotype showed that inhibition of mTOR (mechanistic target of rapamycin), a key regulator of cell growth, lessened the aortic obstruction but did not prevent early postnatal death. We investigated the effects of mTOR inhibition in Eln -null mice partially rescued by human ELN that manifest a less severe arterial phenotype and survive long term. Thoracic aortas of neonatal and juvenile mice with graded elastin deficiency exhibited increased signaling through both mTOR complex 1 and 2. Despite lower predicted wall stress, there was increased phosphorylation of focal adhesion kinase, suggestive of greater integrin activation, and increased transforming growth factor-β-signaling mediators, associated with increased collagen expression. Pharmacological blockade of mTOR by rapalogs did not improve luminal stenosis but reduced mechanosignaling (in delayed fashion after mTOR complex 1 inhibition), medial collagen accumulation, and stiffening of the aorta. Rapalog administration also retarded somatic growth, however, and precipitated neonatal deaths. Complementary, less-toxic strategies to inhibit mTOR via altered growth factor and nutrient responses were not effective. In addition to previously demonstrated therapeutic benefits of rapalogs decreasing smooth muscle cell proliferation in the absence of elastin, we find that rapalogs also prevent aortic fibrosis and stiffening attributable to partial elastin deficiency. Our findings suggest that mTOR-sensitive perturbation of smooth muscle cell mechanosensing contributes to elastin aortopathy. © 2017 American Heart Association, Inc.

Direct detection of crosslinks of collagen and elastin in the hydrolysates of human yellow ligament using single-column high performance liquid chromatography.

PubMed

Chen, J R; Takahashi, M; Kushida, K; Suzuki, M; Suzuki, K; Horiuchi, K; Nagano, A

2000-02-15

Collagen and elastin are recognized as two major connective tissue proteins of human yellow ligament. In both collagen and elastin there are many kinds of intra- or intermolecular crosslinks. Pyridinoline (Pyr) and deoxypyridinoline (Dpyr) are mature crosslinks which maintain the structure of the collagen fibril. Desmosine (Des) and isodesmosine (Isodes) represent the major crosslinking components of elastin. Pentosidine (Pen), which is a senescent crosslink and one of the advanced glycation end products, accumulates with age in tissue proteins including collagen. We developed a direct and one-injection HPLC method to measure Pyr, Dpyr, Des, Isodes, and Pen in the hydrolysate of human yellow ligament. This method used one column and two detectors. Recovery rates of Pyr, Dpyr, Pen, Des, and Isodes were 86.4-98.3, 83.6-96.8, 78.7-95.6, 83.6-97.9, and 85.6-99.3%, respectively (n = 8). The intraassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 3.7, 4.1, 5.4, 4.5, and 4.7%, respectively (n = 8), and the interassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 4.4, 5.1, 4.9, 4.6 and 4.1%, respectively. Linear regression analysis showed the linearity (r = 0.99, P = 0.0001) of calibration line for each Pyr, Dpyr, Pen, Des, and Isodes. Using this method, we investigated age-related changes in the crosslinks of collagen and elastin in human yellow ligament. There was a significant correlation between Pen and age, but no correlations with Pyr, Dpyr, Des, and Isodes. We believe that this method is useful for investigating the content of these crosslinks in both collagen and elastin under various conditions. Copyright 2000 Academic Press.

Compared With Elastin Stains, h-Caldesmon and Desmin Offer Superior Detection of Vessel Invasion in Gastric, Pancreatic, and Colorectal Adenocarcinomas.

PubMed

Ekinci, Özgür; Öğüt, Betül; Çelik, Bülent; Dursun, Ayşe

2018-06-01

The presence of vessel invasion is considered indicative of a poor prognosis in many malignant tumors. We aimed to compare the sensitivity of elastin stains (van Gieson's and orcein methods) with 2 smooth muscle markers (h-caldesmon and desmin) in gastric, pancreatic, and colorectal adenocarcinoma specimens. We used 27 (29.3%) gastric, 35 (38.0%) pancreatic, and 30 (32.6%) colorectal resection specimens. We applied a provisional classification of vessel invasion patterns: type A, a focus with a nearby artery unaccompanied by a vein; type T, a focus at the invasive front without an unaccompanied artery; and type X, foci that only appeared by any of the 4 stains used. There were 369 foci. The smooth muscle markers were more sensitive than the elastin stains, and h-caldesmon more sensitive than desmin, in all types. Among the 139 type A foci, 33 (23.7%) were positive by desmin and h-caldesmon, whereas the elastin stains were not ( P = .001). h-Caldesmon was the only positive marker in 11 (7.9%; P = .011). Among the 78 type T foci, 21 (26.9%) were positive by desmin and h-caldesmon, when both elastin stains were negative ( P = .000). In 16 (20.5%) foci, h-caldesmon was the only positive marker ( P = .002). Among 152 type X foci, 91 (59.9%) were positive by all markers, 26 (17.1%) by both desmin and h-caldesmon, and 9 (5.9%) by only the 2 elastin stains ( P = .001). We recommend these stains for suspect foci in gastric, pancreatic, and colorectal adenocarcinoma specimens. They might highlight both predictable and unpredictable foci.

High-yield recombinant expression and purification of marginally soluble, short elastin-like polypeptides.

PubMed

Bahniuk, Markian S; Alshememry, Abdullah K; Unsworth, Larry D

2016-12-01

The protocol described here is designed as an extension of existing techniques for creating elastin-like polypeptides. It allows for the expression and purification of elastin-like polypeptide (ELP) constructs that are poorly expressed or have very low transition temperatures. DNA concatemerization has been modified to reduce issues caused by methylation sensitivity and inefficient cloning. Linearization of the modified expression vector has been altered to greatly increase cleavage efficiency. The purification regimen is based upon using denaturing metal affinity chromatography to fully solubilize and, if necessary, pre-concentrate the target peptide before purification by inverse temperature cycling (ITC). This protocol has been used to express multiple leucine-containing elastin-like polypeptides, with final yields of 250-660 mg per liter of cells, depending on the specific construct. This was considerably greater than previously reported yields for similar ELPs. Due to the relative hydrophobicity of the tested constructs, even compared with commonly employed ELPs, conventional methods would not have been able to be purify these peptides.

Ferroelectric switching of elastin

PubMed Central

Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

2014-01-01

Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

The OmpL37 surface-exposed protein is expressed by pathogenic Leptospira during infection and binds skin and vascular elastin.

PubMed

Pinne, Marija; Choy, Henry A; Haake, David A

2010-09-07

Pathogenic Leptospira spp. shed in the urine of reservoir hosts into freshwater can be transmitted to a susceptible host through skin abrasions or mucous membranes causing leptospirosis. The infection process involves the ability of leptospires to adhere to cell surface and extracellular matrix components, a crucial step for dissemination and colonization of host tissues. Therefore, the elucidation of novel mediators of host-pathogen interaction is important in the discovery of virulence factors involved in the pathogenesis of leptospirosis. In this study, we assess the functional roles of transmembrane outer membrane proteins OmpL36 (LIC13166), OmpL37 (LIC12263), and OmpL47 (LIC13050), which we recently identified on the leptospiral surface. We determine the capacity of these proteins to bind to host tissue components by enzyme-linked immunosorbent assay. OmpL37 binds elastin preferentially, exhibiting dose-dependent, saturating binding to human skin (K(d), 104±19 nM) and aortic elastin (K(d), 152±27 nM). It also binds fibrinogen (K(d), 244±15 nM), fibrinogen fragment D (K(d), 132±30 nM), plasma fibronectin (K(d), 359±68 nM), and murine laminin (K(d), 410±81 nM). The binding to human skin elastin by both recombinant OmpL37 and live Leptospira interrogans is specifically enhanced by rabbit antiserum for OmpL37, suggesting the involvement of OmpL37 in leptospiral binding to elastin and also the possibility that host-generated antibodies may promote rather than inhibit the adherence of leptospires to elastin-rich tissues. Further, we demonstrate that OmpL37 is recognized by acute and convalescent leptospirosis patient sera and also by Leptospira-infected hamster sera. Finally, OmpL37 protein is detected in pathogenic Leptospira serovars and not in saprophytic Leptospira. Thus, OmpL37 is a novel elastin-binding protein of pathogenic Leptospira that may be promoting attachment of Leptospira to host tissues.

Changes in the composition of the thoracic aortic wall in spontaneously hypertensive rats treated with losartan or spironolactone.

PubMed

Han, Wei-Qing; Wu, Ling-Yun; Zhou, Hai-Yan; Zhang, Jia; Che, Zai-Qian; Wu, Yong-Jie; Liu, Jian-Jun; Zhu, Ding-Liang; Gao, Ping-Jin

2009-05-01

1. In the present study, we compared the elastin and collagen content of thoracic aortic medial and adventitial layers from Wistar-kyoto (WKY) and spontaneously hypertensive rats (SHR). In addition, the effects of losartan, an angiotensin II receptor antagonist, and spironolactone, a mineralocorticoid receptor antagonist, on collagen and elastin content were determined. 2. Prehypertensive (4-week-old) and hypertensive (16-week-old) SHR were randomly divided into three groups treated with either 0.9% NaCl, losartan (20 mg/kg per day) or spironolactone (200 mg/kg per day). Prehypertensive and hypertensive SHR were treated for 12 and 16 weeks, respectively. Age-matched WKY rats were not treated with NaCl, losartan or spironolactone and served as the control group. 3. The medial and adventitial layers of the thoracic aorta were composed mainly of elastin and collagen, respectively, in both SHR and WKY rats. Compared with WKY rats, SHR exhibited greater collagen and elastin content in the media, but decreased collagen and elastin content in the adventitial layer. Both medial and adventitial collagen and elastin content increased significantly with age in both strains and was greater in 32-week-old rats compared with 16-week-old rats. Spironolactone treatment decreased collagen content in the media of thoracic aortas from prehypertensive SHR, whereas losartan decreased collagen content in the media of aortas from hypertensive SHR. In contrast, neither spironolactone nor losartan had any effect on adventitial collagen content in prehypertensive and hypertensive SHR. Medial collagen and elastin were positively related to pulse pressure (PP), but there was no correlation between adventitial mass or collagen content and PP or mean arterial pressure in untreated and treated SHR and WKY rats. 4. In conclusion, the composition of the medial and adventitial layers of the thoracic aorta differs and treatment of SHR with losartan and spironolactone decreases collagen content when delivered at the hypertensive or prehypertensive stage, respectively. However, neither drug has any effect on adventitial collagen content in SHR.

[Study on bamboo treated with gamma rays by X-ray diffraction].

PubMed

Sun, Feng-Bo; Fei, Ben-Hua; Jiang, Ze-Hui; Yu, Zi-Xuan; Tian, Gen-Lin; Yang, Quan-Wen

2011-06-01

The microfibril angle and crystallinity of bamboo treated with gamma rays were tested by X-ray diffraction (XRD). The result indicated that crystallinity in bamboo increased when irradiation dose was less than 100 kGy, while the irradiation dose was raised to about 100 kGy, crystallinity in bamboo reduced. But during the whole irradiation process, the influence on microfibril angle was not obvious, so it was not the dominant factors on variation in physical-mechanical properties of bamboo during the process of irradiation.

Confocal microscopy for automatic measurement of the density and distance between elastin fibers of histologic preparations of normotensive and hypertensive patients

NASA Astrophysics Data System (ADS)

Vieira, G.; Ferro, D. P.; Adam, R. L.; de Thomaz, A. A.; Cesar, C. L.; Metze, K.

2010-02-01

Elastic fibers are essential components of the human aorta, and there is an association between elastin fibers remodeling and several diseases. Hypertension is one such example of a disease leading to elastin fibers remodeling. These fibers can be easily seen in eosin-hematoxilin (HE) stained histologic sections when observed by UV-excited fluorescence microscopy or by a much more precise Laser Scanning Confocal Microscope (LSCM). In order to study the effect of the hypertension on the elastin fibers pattern we developed an automatic system (software and hardware) to count the number of elastin fibers and to measure the distance between them in a LSCM and used it compare the statistical distribution of the distance between these fibers in normotensive and hypertensive patients. The full image of the whole sample (2 or 3mm long) was composed by several 220×220μm frames with 512×512 pixels. The software counters fiber and distance between fibers. We compared the elastic fiber texture in routinely HE-stained histologic slides of the aorta ascendens in 24 normotensive and 30 hypertensive adult patients of both sexes and of similar age from our autopsy files. Our results show that the average number of fibers is the same for both cases but the distance between the fibers are larger for hypertensive patients than for normotensive ones.

Hydrogels for lung tissue engineering: Biomechanical properties of thin collagen-elastin constructs.

PubMed

Dunphy, Siobhán E; Bratt, Jessica A J; Akram, Khondoker M; Forsyth, Nicholas R; El Haj, Alicia J

2014-10-01

In this study, collagen-elastin constructs were prepared with the aim of producing a material capable of mimicking the mechanical properties of a single alveolar wall. Collagen has been used in a wide range of tissue engineering applications; however, due to its low mechanical properties its use is limited to non load-bearing applications without further manipulation using methods such as cross-linking or mechanical compression. Here, it was hypothesised that the addition of soluble elastin to a collagen hydrogel could improve its mechanical properties. Hydrogels made from collagen only and collagen plus varying amounts elastin were prepared. Young׳s modulus of each membrane was measured using the combination of a non-destructive indentation and a theoretical model previously described. An increase in Young׳s modulus was observed with increasing concentration of elastin. The use of non-destructive indentation allowed for online monitoring of the elastic moduli of cell-seeded constructs over 8 days. The addition of lung fibroblasts into the membrane increased the stiffness of the hydrogels further and cell-seeded collagen hydrogels were found to have a stiffness equal to the theoretical value for a single alveolar wall (≈5kPa). Through provision of some of the native extracellular matrix components of the lung parenchyma these scaffolds may be able to provide an initial building block toward the regeneration of new functional lung tissue. Copyright © 2014 Elsevier Ltd. All rights reserved.

Morphometric changes in the aortic arch with advancing age in fetal to mature thoroughbred horses.

PubMed

Endoh, Chihiro; Matsuda, Kazuya; Okamoto, Minoru; Tsunoda, Nobuo; Taniyama, Hiroyuki

2017-03-28

Aortic rupture is a well recognized cause of sudden death in thoroughbred horses. Some microscopic lesions, such as those caused by cystic medial necrosis and medionecrosis, can lead to aortic rupture. However, these microscopic lesions are also observed in normal horses. On the other hand, a previous study of aortic rupture suggested that underlying elastin and collagen deposition disorders might be associated with aortic rupture. Therefore, the purpose of this study was to compare the structural components of the tunica media of the aortic arch, which is composed of elastin, collagen, smooth muscle cells and mucopolysaccharides (MPS), in fetal to mature thoroughbred horses. The percentage area of elastin was greatest in the young horses and subsequently decreased with aging. The percentage area of collagen increased with aging, and the elderly horses (aged ≥20) exhibited significantly higher percentage areas of collagen than the young horses. The percentage area of smooth muscle cells did not change with age. The percentage area of MPS was inversely proportional to the percentage area of elastin. The fetuses exhibited a markedly larger percentage area of MPS than the mature horses. We concluded that the medial changes seen in the aortic arch, which included a reduction in the amount of elastin and increases in the amounts of collagen and MPS, were age-related variations.

Human elastin polypeptides improve the biomechanical properties of three-dimensional matrices through the regulation of elastogenesis.

PubMed

Boccafoschi, Francesca; Ramella, Martina; Sibillano, Teresa; De Caro, Liberato; Giannini, Cinzia; Comparelli, Roberto; Bandiera, Antonella; Cannas, Mario

2015-03-01

The replacement of diseased tissues with biological substitutes with suitable biomechanical properties is one of the most important goal in tissue engineering. Collagen represents a satisfactory choice for scaffolds. Unfortunately, the lack of elasticity represents a restriction to a wide use of collagen for several applications. In this work, we studied the effect of human elastin-like polypeptide (HELP) as hybrid collagen-elastin matrices. In particular, we studied the biomechanical properties of collagen/HELP scaffolds considering several components involved in ECM remodeling (elastin, collagen, fibrillin, lectin-like receptor, metalloproteinases) and cell phenotype (myogenin, myosin heavy chain) with particular awareness for vascular tissue engineering applications. Elastin and collagen content resulted upregulated in collagen-HELP matrices, even showing an improved structural remodeling through the involvement of proteins to a ECM remodeling activity. Moreover, the hybrid matrices enhanced the contractile activity of C2C12 cells concurring to improve the mechanical properties of the scaffold. Finally, small-angle X-ray scattering analyses were performed to enable a very detailed analysis of the matrices at the nanoscale, comparing the scaffolds with native blood vessels. In conclusion, our work shows the use of recombinant HELP, as a very promising complement able to significantly improve the biomechanical properties of three-dimensional collagen matrices in terms of tensile stress and elastic modulus. © 2014 Wiley Periodicals, Inc.

Simultaneous influence of pectin and xyloglucan on structure and mechanical properties of bacterial cellulose composites.

PubMed

Szymańska-Chargot, Monika; Chylińska, Monika; Cybulska, Justyna; Kozioł, Arkadiusz; Pieczywek, Piotr M; Zdunek, Artur

2017-10-15

The impact of the matrix polysaccharides on the cellulose microfibrils structure as well as on the mechanical properties of cell walls still remains an open question. Therefore, the aim of investigations was to determine the simultaneous influence of (i) different concentrations of pectins with constant concentration of xyloglucan, and (ii) different concentrations of xyloglucan with constant concentration of pectins on cellulose structure. Composites of bacterial cellulose (BC) produced by Komagataeibacter xylinus are considered to mimic natural plant cell walls. This investigation showed that the lower the ratio of xyloglucan to pectin was, the higher Young's modulus of BC composite was and also obtained cellulose microfibrils were thinner. The increasing concentration of xyloglucan to pectin also caused the drop down in microfibrils crystallinity degree with predominant structure of cellulose I β . In that case, also the length of cellulose chains was growing and reaching the highest value among all BC composites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanical behavior of cellulose microfibrils in tension wood, in relation with maturation stress generation.

PubMed

Clair, Bruno; Alméras, Tancrède; Yamamoto, Hiroyuki; Okuyama, Takashi; Sugiyama, Junji

2006-08-01

A change in cellulose lattice spacing can be detected during the release of wood maturation stress by synchrotron x-ray diffraction experiment. The lattice strain was found to be the same order of magnitude as the macroscopic strain. The fiber repeat distance, 1.033 nm evaluated for tension wood after the release of maturation stress was equal to the conventional wood values, whereas the value before stress release was larger, corresponding to a fiber repeat of 1.035 nm, nearly equal to that of cotton and ramie. Interestingly, the fiber repeat varied from 1.033 nm for wood to 1.040 nm for algal cellulose, with an increasing order of lateral size of cellulose microfibrils so far reported. These lines of experiments demonstrate that, before the stress release, the cellulose was in a state of tension, which is, to our knowledge, the first experimental evidence supporting the assumption that tension is induced in cellulose microfibrils.

Folding of xylan onto cellulose fibrils in plant cell walls revealed by solid-state NMR

NASA Astrophysics Data System (ADS)

Simmons, Thomas J.; Mortimer, Jenny C.; Bernardinelli, Oigres D.; Pöppler, Ann-Christin; Brown, Steven P.; Deazevedo, Eduardo R.; Dupree, Ray; Dupree, Paul

2016-12-01

Exploitation of plant lignocellulosic biomass is hampered by our ignorance of the molecular basis for its properties such as strength and digestibility. Xylan, the most prevalent non-cellulosic polysaccharide, binds to cellulose microfibrils. The nature of this interaction remains unclear, despite its importance. Here we show that the majority of xylan, which forms a threefold helical screw in solution, flattens into a twofold helical screw ribbon to bind intimately to cellulose microfibrils in the cell wall. 13C solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, supported by in silico predictions of chemical shifts, shows both two- and threefold screw xylan conformations are present in fresh Arabidopsis stems. The twofold screw xylan is spatially close to cellulose, and has similar rigidity to the cellulose microfibrils, but reverts to the threefold screw conformation in the cellulose-deficient irx3 mutant. The discovery that induced polysaccharide conformation underlies cell wall assembly provides new principles to understand biomass properties.

Folding of xylan onto cellulose fibrils in plant cell walls revealed by solid-state NMR.

PubMed

Simmons, Thomas J; Mortimer, Jenny C; Bernardinelli, Oigres D; Pöppler, Ann-Christin; Brown, Steven P; deAzevedo, Eduardo R; Dupree, Ray; Dupree, Paul

2016-12-21

Exploitation of plant lignocellulosic biomass is hampered by our ignorance of the molecular basis for its properties such as strength and digestibility. Xylan, the most prevalent non-cellulosic polysaccharide, binds to cellulose microfibrils. The nature of this interaction remains unclear, despite its importance. Here we show that the majority of xylan, which forms a threefold helical screw in solution, flattens into a twofold helical screw ribbon to bind intimately to cellulose microfibrils in the cell wall. 13 C solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, supported by in silico predictions of chemical shifts, shows both two- and threefold screw xylan conformations are present in fresh Arabidopsis stems. The twofold screw xylan is spatially close to cellulose, and has similar rigidity to the cellulose microfibrils, but reverts to the threefold screw conformation in the cellulose-deficient irx3 mutant. The discovery that induced polysaccharide conformation underlies cell wall assembly provides new principles to understand biomass properties.

Finite element 3D modeling of mechanical behavior of mineralized collagen microfibrils.

PubMed

Barkaoui, Abdelwahed; Hambli, Ridha

2011-01-01

The aim of this work is to develop a 3D finite elements model to study the nanomechanical behavior of mineralized collagen microfibrils, which consists of three phases, (i) collagen phase formed by five tropocollagen (TC) molecules linked together with cross-links, (ii) a mineral phase (Hydroxyapatite), and (iii) impure mineral phase, and to investigate the important role of individual properties of every constituent. The mechanical and geometric properties (TC molecule diameter) of both tropocollagen and mineral were taken into consideration as well as cross-links, which was represented by spring elements with adjusted properties based on experimental data. In this paper an equivalent homogenized model was developed to assess the whole microfibril mechanical properties (Young's modulus and Poisson's ratio) under varying mechanical properties of each phase. In this study, both equivalent Young's modulus and Poisson's ratio, which were expressed as functions of Young's modulus of each phase, were obtained under tensile load with symmetric and periodic boundary conditions.

Preparation using pectinase and characterization of nanofibers from orange peel waste in juice factories.

PubMed

Hideno, Akihiro; Abe, Kentaro; Yano, Hiroyuki

2014-06-01

This study reports the preparation and characterization of nanofibers consisting mainly of cellulose microfibrils from orange peel (OP), which is a significant byproduct of orange juice production. Three treatments (boiling, alkaline, and pectinase) were investigated with and without subsequent grinding treatment. It was possible to prepare the cellulose nanofibers (CNFs) using these methods, except for the boiling treatment with grinding. Interestingly, only pectinase and a mild-physical blender treatment without grinding produced nanofibers. The width of the nanofibers from OP was approximately 10 to 50 nm. The microfibril bundles of OP were considered to be thinner than those of commercial CNFs. Our data indicated that the removal of pectic polysaccharides and hemicelluloses covering the cellulose microfibrils was important for the preparation of nanofibers from OP. These nanofibers from OP using pectinase are proposed to be applicable as food materials, pharmaceuticals, and filters for the tractive characteristics of the sheet. This study demonstrates: (1) it was possible to prepare the nanofibers from orange peel using pectinase and (2) the width of the nanofibers from orange peel was approximately 10 to 50 nm. (3) Removal of polysaccharides such as pectin and hemicelluloses covering cellulose microfibrils was very important for preparation of nanofibers from OP. Considering the tractive characteristics of the sheets from nanofibers and the origin of orange peel, they are suitable for application of food materials, pharmaceuticals, and filters. © 2014 Institute of Food Technologists®

WallGen, software to construct layered cellulose-hemicellulose networks and predict their small deformation mechanics.

PubMed

Kha, Hung; Tuble, Sigrid C; Kalyanasundaram, Shankar; Williamson, Richard E

2010-02-01

We understand few details about how the arrangement and interactions of cell wall polymers produce the mechanical properties of primary cell walls. Consequently, we cannot quantitatively assess if proposed wall structures are mechanically reasonable or assess the effectiveness of proposed mechanisms to change mechanical properties. As a step to remedying this, we developed WallGen, a Fortran program (available on request) building virtual cellulose-hemicellulose networks by stochastic self-assembly whose mechanical properties can be predicted by finite element analysis. The thousands of mechanical elements in the virtual wall are intended to have one-to-one spatial and mechanical correspondence with their real wall counterparts of cellulose microfibrils and hemicellulose chains. User-defined inputs set the properties of the two polymer types (elastic moduli, dimensions of microfibrils and hemicellulose chains, hemicellulose molecular weight) and their population properties (microfibril alignment and volume fraction, polymer weight percentages in the network). This allows exploration of the mechanical consequences of variations in nanostructure that might occur in vivo and provides estimates of how uncertainties regarding certain inputs will affect WallGen's mechanical predictions. We summarize WallGen's operation and the choice of values for user-defined inputs and show that predicted values for the elastic moduli of multinet walls subject to small displacements overlap measured values. "Design of experiment" methods provide systematic exploration of how changed input values affect mechanical properties and suggest that changing microfibril orientation and/or the number of hemicellulose cross-bridges could change wall mechanical anisotropy.

Adsorption behavior of optical brightening agent on microfibrillated cellulose studied through inverse liquid chromatography: The need to correct for axial dispersion effect.

PubMed

Serroukh, Sonia; Huber, Patrick; Lallam, Abdelaziz

2018-01-19

Inverse liquid chromatography is a technique for studying solid/liquid interaction and most specifically for the determination of solute adsorption isotherm. For the first time, the adsorption behaviour of microfibrillated cellulose was assessed using inverse liquid chromatography. We showed that microfibrillated cellulose could adsorb 17 mg/g of tetrasulfonated optical brightening agent in typical papermaking conditions. The adsorbed amount of hexasulfonated optical brightening agent was lower (7 mg/g). The packing of the column with microfibrillated cellulose caused important axial dispersion (D a  = 5e-7 m²/s). Simulation of transport phenomena in the column showed that neglecting axial dispersion in the analysis of the chromatogram caused significant error (8%) in the determination of maximum adsorbed amount. We showed that conventional chromatogram analysis technique such as elution by characteristic point could not be used to fit our data. Using a bi-Langmuir isotherm model improved the fitting, but did not take into account axial dispersion, thus provided adsorption parameters which may have no physical significance. Using an inverse method with a single Langmuir isotherm, and fitting the transport equation to the chromatogram was shown to provide a satisfactory fitting to the chromatogram data. In general, the inverse method could be recommended to analyse inverse liquid chromatography data for column packing with significant axial dispersion (D a   > 1e-7 m²/s). Copyright © 2017 Elsevier B.V. All rights reserved.

Elastin cross-linking in the skin from patients with amyotrophic lateral sclerosis

NASA Technical Reports Server (NTRS)

Ono, S.; Yamauchi, M.

1994-01-01

Two cross-links unique to elastin, desmosine and isodesmosine were measured and compared in skin tissue (left upper arm) from 10 patients with amyotrophic lateral sclerosis (ALS) and from seven age-matched controls. The contents of desmosine and isodesmosine were significantly decreased (p < 0.01 and p < 0.01, respectively) in patients with ALS compared with those of controls, and were negatively and significantly associated with duration of illness in ALS patients (r = -0.77, p < 0.01 and r = -0.65, p < 0.05, respectively). The decline in skin desmosine and isodesmosine is more rapid in ALS than in normal ageing. Thus cross-linking of skin elastin is affected in ALS.

Development of Intra-Articular Drug Delivery to Alter Progression of Arthritis Following Joint Injury

DTIC Science & Technology

2013-04-01

sTNFRII in combination. The treatments were encapsulated in elastin -like polypeptide (ELP) drug depots that have been associated with a 25-fold...or both IL-1Ra and sTNFRII. The drugs were encapsulated in elastin -like polypeptide (ELP) drug depots that slowly disaggregate for prolonged IA

An Investigation of Voice Quality in Individuals with Inherited Elastin Gene Abnormalities

ERIC Educational Resources Information Center

Watts, Christopher R.; Awan, Shaheen N.; Marler, Jeffrey A.

2008-01-01

The human elastin gene (ELN) is responsible for the generation of elastic fibres in the extracellular matrix of connective tissue throughout the body, including the vocal folds. Individuals with Supravalvular aortic stenosis (SVAS) and Williams syndrome (WS) lack one normal ELN allele due to heterozygous ELN abnormalities, resulting in a…

Human umbilical cord-derived mesenchymal stem cells protect from hyperoxic lung injury by ameliorating aberrant elastin remodeling in the lung of O2-exposed newborn rat.

PubMed

Hou, Chen; Peng, Danyi; Gao, Li; Tian, Daiyin; Dai, Jihong; Luo, Zhengxiu; Liu, Enmei; Chen, Hong; Zou, Lin; Fu, Zhou

2018-01-08

The incidence and mortality rates of bronchopulmonary dysplasia (BPD) remain very high. Therefore, novel therapies are imminently needed to improve the outcome of this disease. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) show promising therapeutic effects on oxygen-induced model of BPD. In our experiment, UC-MSCs were intratracheally delivered into the newborn rats exposed to hyperoxia, a well-established BPD model. This study demonstrated that UC-MSCs reduce elastin expression stimulated by 90% O 2 in human lung fibroblasts-a (HLF-a), and inhibit HLF-a transdifferentiation into myofibroblasts. In addition, the therapeutic effects of UC-MSCs in neonatal rats with BPD, UC-MSCs could inhibit lung elastase activity and reduce aberrant elastin expression and deposition in the lung of BPD rats. Overall, this study suggested that UC-MSCs could ameliorate aberrant elastin expression in the lung of hyperoxia-induced BPD model which may be associated with suppressing increased TGFβ1 activation. Copyright © 2017. Published by Elsevier Inc.

Measurement of the Exchange Rate of Waters of Hydration in Elastin by 2D T(2)-T(2) Correlation Nuclear Magnetic Resonance Spectroscopy.

PubMed

Sun, Cheng; Boutis, Gregory S

2011-02-28

We report on the direct measurement of the exchange rate of waters of hydration in elastin by T(2)-T(2) exchange spectroscopy. The exchange rates in bovine nuchal ligament elastin and aortic elastin at temperatures near, below and at the physiological temperature are reported. Using an Inverse Laplace Transform (ILT) algorithm, we are able to identify four components in the relaxation times. While three of the components are in good agreement with previous measurements that used multi-exponential fitting, the ILT algorithm distinguishes a fourth component having relaxation times close to that of free water and is identified as water between fibers. With the aid of scanning electron microscopy, a model is proposed allowing for the application of a two-site exchange analysis between any two components for the determination of exchange rates between reservoirs. The results of the measurements support a model (described elsewhere [1]) wherein the net entropy of bulk waters of hydration should increase upon increasing temperature in the inverse temperature transition.

Elastin in large artery stiffness and hypertension

PubMed Central

Wagenseil, Jessica E.; Mecham, Robert P.

2012-01-01

Large artery stiffness, as measured by pulse wave velocity (PWV), is correlated with high blood pressure and may be a causative factor in essential hypertension. The extracellular matrix components, specifically the mix of elastin and collagen in the vessel wall, determine the passive mechanical properties of the large arteries. Elastin is organized into elastic fibers in the wall during arterial development in a complex process that requires spatial and temporal coordination of numerous proteins. The elastic fibers last the lifetime of the organism, but are subject to proteolytic degradation and chemical alterations that change their mechanical properties. This review discusses how alterations in the amount, assembly, organization or chemical properties of the elastic fibers affect arterial stiffness and blood pressure. Strategies for encouraging or reversing alterations to the elastic fibers are addressed. Methods for determining the efficacy of these strategies, by measuring elastin amounts and arterial stiffness, are summarized. Therapies that have a direct effect on arterial stiffness through alterations to the elastic fibers in the wall may be an effective treatment for essential hypertension. PMID:22290157

Quantitative and qualitative evaluation of dermal elastin of draught horses with chronic progressive lymphoedema.

PubMed

De Cock, H E V; Van Brantegem, L; Affolter, V K; Oosterlinck, M; Ferraro, G L; Ducatelle, R

2009-01-01

Chronic progressive lymphoedema (CPL) in horses, a disease of certain draught breeds, is associated with altered elastin metabolism. The characteristic lesions are seen in the skin of the lower (distal) limbs. This study was based on horses of susceptible breeds, with and without CPL, and on horses of a non-susceptible breed. Skin samples were obtained for examination from the neck (considered a non-affected region) and from the distal limb. The skin lesions were characterized histologically and the dermal elastic fibres were evaluated morphologically and quantitatively. In all horses the mean elastin concentrations were highest in the superficial dermis, gradually decreasing in the mid-dermis and deep dermis. As compared with horses of a non-susceptible breed, affected horses had increased amounts of dermal elastin in both the distal limb and neck, while non-affected horses of a susceptible breed had decreased amounts. The findings support an earlier hypothesis that CPL of horses is a generalized disease. Reduced efficiency of the elastic network in supporting the dermal lymphatics may explain the development of CPL.

Vascular replacement using a layered elastin-collagen vascular graft in a porcine model: one week patency versus one month occlusion

PubMed Central

Koens, M J W; Krasznai, A G; Hanssen, A E J; Hendriks, T; Praster, R; Daamen, W F; van der Vliet, J A; van Kuppevelt, T H

2015-01-01

abstract A persistent clinical demand exists for a suitable arterial prosthesis. In this study, a vascular conduit mimicking the native 3-layered artery, and constructed from the extracellular matrix proteins type I collagen and elastin, was evaluated for its performance as a blood vessel equivalent. A tubular 3-layered graft (elastin-collagen-collagen) was prepared using highly purified type I collagen fibrils and elastin fibers, resembling the 3-layered native blood vessel architecture. The vascular graft was crosslinked and heparinised (37 ± 4 μg heparin/mg graft), and evaluated as a vascular graft using a porcine bilateral iliac artery model. An intra-animal comparison with clinically-used heparinised ePTFE (Propaten®) was made. Analyses included biochemical characterization, duplex scanning, (immuno)histochemistry and scanning electron microscopy. The tubular graft was easy to handle with adequate suturability. Implantation resulted in pulsating grafts without leakage. One week after implantation, both ePTFE and the natural acellular graft had 100% patencies on duplex scanning. Grafts were partially endothelialised (Von Willebrand-positive endothelium with a laminin-positive basal membrane layer). After one month, layered thrombi were found in the natural (4/4) and ePTFE graft (1/4), resulting in occlusion which in case of the natural graft is likely due to the porosity of the inner elastin layer. In vivo application of a molecularly-defined tubular graft, based on nature's matrix proteins, for vascular surgery is feasible. PMID:26060888

Targeted chelation therapy with EDTA-loaded albumin nanoparticles regresses arterial calcification without causing systemic side effects

PubMed Central

Lei, Yang; Nosoudi, Nasim; Vyavahare, Naren

2014-01-01

Background and aims Elastin-specific medial arterial calcification (MAC) is an arterial disease commonly referred as Monckeberg’s sclerosis. It causes significant arterial stiffness, and as yet, no clinical therapy exists to prevent or reverse it. We developed albumin nanoparticles (NPs) loaded with disodium ethylene diaminetetraacetic acid (EDTA) that were designed to target calcified elastic lamina when administrated by intravenous injection. Methods and Results We optimized NP size, charge, and EDTA-loading efficiency (150~200 nm, zeta potential of − 22.89 ~ − 31.72 mV, loading efficiency for EDTA ~20 %) for in vivo targeting in rats. These NPs released EDTA slowly for up to 5 days. In both ex-vivo study and in vivo study with injury-induced local abdominal aortic calcification, we showed that elastin antibody-coated and EDTA-loaded albumin NPs targeted the damaged elastic lamina while sparing healthy artery. Intravenous NP injections reversed elastin-specific MAC in rats after four injections over a 2-week period. EDTA-loaded albumin NPs did not cause the side effects observed in EDTA injection alone, such as decrease in serum calcium (Ca), increase in urine Ca, or toxicity to kidney. There was no bone loss in any treated groups. Conclusion We demonstrate that elastin antibody-coated and EDTA-loaded albumin NPs might be a promising nanoparticle therapy to reverse elastin-specific MAC and circumvent side effects associated with systemic EDTA chelation therapy. PMID:25285609

Elastin aging and lipid oxidation products in human aorta.

PubMed

Zarkovic, Kamelija; Larroque-Cardoso, Pauline; Pucelle, Mélanie; Salvayre, Robert; Waeg, Georg; Nègre-Salvayre, Anne; Zarkovic, Neven

2015-01-01

Vascular aging is associated with structural and functional modifications of the arteries, and by an increase in arterial wall thickening in the intima and the media, mainly resulting from structural modifications of the extracellular matrix (ECM) components. Among the factors known to accumulate with aging, advanced lipid peroxidation end products (ALEs) are a hallmark of oxidative stress-associated diseases such as atherosclerosis. Aldehydes generated from the peroxidation of polyunsaturated fatty acids (PUFA), (4-hydroxynonenal, malondialdehyde, acrolein), form adducts on cellular proteins, leading to a progressive protein dysfunction with consequences in the pathophysiology of vascular aging. The contribution of these aldehydes to ECM modification is not known. This study was carried out to investigate whether aldehyde-adducts are detected in the intima and media in human aorta, whether their level is increased in vascular aging, and whether elastin fibers are a target of aldehyde-adduct formation. Immunohistological and confocal immunofluorescence studies indicate that 4-HNE-histidine-adducts accumulate in an age-related manner in the intima, media and adventitia layers of human aortas, and are mainly expressed in smooth muscle cells. In contrast, even if the structure of elastin fiber is strongly altered in the aged vessels, our results show that elastin is not or very poorly modified by 4-HNE. These data indicate a complex role for lipid peroxidation and in particular for 4-HNE in elastin homeostasis, in the vascular wall remodeling during aging and atherosclerosis development. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Elastin aging and lipid oxidation products in human aorta

PubMed Central

Zarkovic, Kamelija; Larroque-Cardoso, Pauline; Pucelle, Mélanie; Salvayre, Robert; Waeg, Georg; Nègre-Salvayre, Anne; Zarkovic, Neven

2014-01-01

Vascular aging is associated with structural and functional modifications of the arteries, and by an increase in arterial wall thickening in the intima and the media, mainly resulting from structural modifications of the extracellular matrix (ECM) components. Among the factors known to accumulate with aging, advanced lipid peroxidation end products (ALEs) are a hallmark of oxidative stress-associated diseases such as atherosclerosis. Aldehydes generated from the peroxidation of polyunsaturated fatty acids (PUFA), (4-hydroxynonenal, malondialdehyde, acrolein), form adducts on cellular proteins, leading to a progressive protein dysfunction with consequences in the pathophysiology of vascular aging. The contribution of these aldehydes to ECM modification is not known. This study was carried out to investigate whether aldehyde-adducts are detected in the intima and media in human aorta, whether their level is increased in vascular aging, and whether elastin fibers are a target of aldehyde-adduct formation. Immunohistological and confocal immunofluorescence studies indicate that 4-HNE-histidine-adducts accumulate in an age-related manner in the intima, media and adventitia layers of human aortas, and are mainly expressed in smooth muscle cells. In contrast, even if the structure of elastin fiber is strongly altered in the aged vessels, our results show that elastin is not or very poorly modified by 4-HNE. These data indicate a complex role for lipid peroxidation and in particular for 4-HNE in elastin homeostasis, in the vascular wall remodeling during aging and atherosclerosis development. PMID:25553420

Quantification of aortic and cutaneous elastin and collagen morphology in Marfan syndrome by multiphoton microscopy.

PubMed

Cui, Jason Z; Tehrani, Arash Y; Jett, Kimberly A; Bernatchez, Pascal; van Breemen, Cornelis; Esfandiarei, Mitra

2014-09-01

In a mouse model of Marfan syndrome, conventional Verhoeff-Van Gieson staining displays severe fragmentation, disorganization and loss of the aortic elastic fiber integrity. However, this method involves chemical fixatives and staining, which may alter the native morphology of elastin and collagen. Thus far, quantitative analysis of fiber damage in aorta and skin in Marfan syndrome has not yet been explored. In this study, we have used an advanced noninvasive and label-free imaging technique, multiphoton microscopy to quantify fiber fragmentation, disorganization, and total volumetric density of aortic and cutaneous elastin and collagen in a mouse model of Marfan syndrome. Aorta and skin samples were harvested from Marfan and control mice aged 3-, 6- and 9-month. Elastin and collagen were identified based on two-photon excitation fluorescence and second-harmonic-generation signals, respectively, without exogenous label. Measurement of fiber length indicated significant fragmentation in Marfan vs. control. Fast Fourier transform algorithm analysis demonstrated markedly lower fiber organization in Marfan mice. Significantly reduced volumetric density of elastin and collagen and thinner skin dermis were observed in Marfan mice. Cutaneous content of elastic fibers and thickness of dermis in 3-month Marfan resembled those in the oldest control mice. Our findings of early signs of fiber degradation and thinning of skin dermis support the potential development of a novel non-invasive approach for early diagnosis of Marfan syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.

Diversity in the organization of elastin bundles and intramembranous muscles in bat wings.

PubMed

Cheney, Jorn A; Allen, Justine J; Swartz, Sharon M

2017-04-01

Unlike birds and insects, bats fly with wings composed of thin skin that envelops the bones of the forelimb and spans the area between the limbs, digits, and sometimes the tail. This skin is complex and unusual; it is thinner than typical mammalian skin and contains organized bundles of elastin and embedded skeletal muscles. These elements are likely responsible for controlling the shape of the wing during flight and contributing to the aerodynamic capabilities of bats. We examined the arrangement of two macroscopic architectural elements in bat wings, elastin bundles and wing membrane muscles, to assess the diversity in bat wing skin morphology. We characterized the plagiopatagium and dactylopatagium of 130 species from 17 families of bats using cross-polarized light imaging. This method revealed structures with distinctive relative birefringence, heterogeneity of birefringence, variation in size, and degree of branching. We used previously published anatomical studies and tissue histology to identify birefringent structures, and we analyzed their architecture across taxa. Elastin bundles, muscles, neurovasculature, and collagenous fibers are present in all species. Elastin bundles are oriented in a predominantly spanwise or proximodistal direction, and there are five characteristic muscle arrays that occur within the plagiopatagium, far more muscle than typically recognized. These results inform recent functional studies of wing membrane architecture, support the functional hypothesis that elastin bundles aid wing folding and unfolding, and further suggest that all bats may use these architectural elements for flight. All species also possess numerous muscles within the wing membrane, but the architecture of muscle arrays within the plagiopatagium varies among families. To facilitate present and future discussion of these muscle arrays, we refine wing membrane muscle nomenclature in a manner that reflects this morphological diversity. The architecture of the constituents of the skin of the wing likely plays a key role in shaping wings during flight. © 2017 Anatomical Society.

International Congress of Biorheology (3rd) Held at the University of California, San Diego on August 28 - September 1, 1978.

DTIC Science & Technology

1979-01-30

12. Hemorheology and Hemodynamics 13. New Hypotheses in Hemorheology and Muscle Contraction 14. Bone and Cartilage 15. Tissue Space 16. Elastin...Hemodynamics 13. New Hypotheses in Hemorheology and Muscle Contraction 14. Bone and Cartilage 15. Tissue Space 16. Elastin, Collagen and Tendons 17. Clinical

Acoustic fingerprints of dye-labeled protein submicrosphere photoacoustic contrast agents

NASA Astrophysics Data System (ADS)

McDonald, Michael A.; Jankovic, Ladislav; Shahzad, Khalid; Burcher, Michael; Li, King C. P.

2009-05-01

Dye-labeled protein microspheres, submicron in size and capable of producing thermoelastically generated ultrasound in response to laser stimulation, are presented as contrast agents for photoacoustic imaging. Incident laser energy absorbed by fluorescein isothiocyanate (FITC)-labeled elastin submicrospheres results in thermoelastically generated sound production. Plotted A-line graphs reveal a distinctive morphology and a greater than two orders of magnitude increase in signal amplitude subsequent to converting FITC elastin into submicrospheres (despite a four orders of magnitude decrease in concentration). Evidence of nonlinearity and enhancement of ultrasound backscatter indicate a potential use in contrast-enhanced harmonic imaging. Photoacoustic and ultrasound imaging of FITC-elastin submicrospheres in a water-filled phantom vessel shows enhanced contrast at low concentration and clear delineation of the phantom vessel wall.

Patterns of cell elongation in the determination of the final shape in galls of Baccharopelma dracunculifoliae (Psyllidae) on Baccharis dracunculifolia DC (Asteraceae).

PubMed

Magalhães, Thiago Alves; de Oliveira, Denis Coelho; Suzuki, Aline Yasko Marinho; Isaias, Rosy Mary dos Santos

2014-07-01

Cell redifferentiation, division, and elongation are recurrent processes, which occur during gall development, and are dependent on the cellulose microfibrils reorientation. We hypothesized that changes in the microfibrils orientation from non-galled tissues to galled ones occur and determine the final gall shape. This determination is caused by a new tissue zonation, its hyperplasia, and relative cell hypertrophy. The impact of the insect's activity on these patterns of cell development was herein tested in Baccharopelma dracunculifoliae-Baccharis dracunculifolia system. In this system, the microfibrils are oriented perpendicularly to the longest cell axis in elongated cells and randomly in isodiametric ones, either in non-galled or in galled tissues. The isodiametric cells of the abaxial epidermis in non-galled tissues divided and elongated periclinally, forming the outer gall epidermis. The anticlinally elongated cells of the abaxial palisade layer and the isodiametric cells of the spongy parenchyma originated the gall outer cortex with hypertrophied and periclinally elongated cells. The anticlinally elongated cells of the adaxial palisade layer originated the inner cortex with hypertrophied and periclinally elongated cells in young and mature galls and isodiametric cells in senescent galls. The isodiametric cells of the adaxial epidermis elongated periclinally in the inner gall epidermis. The current investigation demonstrates the role of cellulose microfibril reorientation for gall development. Once many factors other than this reorientation act on gall development, it should be interesting to check the possible relationship of the new cell elongation patterns with the pectic composition of the cell walls.

Application of a quick-freezing and deep-etching method to pathological diagnosis: a case of elastofibroma.

PubMed

Hemmi, Akihiro; Tabata, Masahiko; Homma, Taku; Ohno, Nobuhiko; Terada, Nobuo; Fujii, Yasuhisa; Ohno, Shinichi; Nemoto, Norimichi

2006-04-01

A case of elastofibroma in a middle-aged Japanese woman was examined by the quick-freezing and deep-etching (QF-DE) method, as well as by immunohistochemistry and conventional electron microscopy. The slowly growing tumor developed at the right scapular region and was composed of fibrous connective tissue with unique elastic materials called elastofibroma fibers. A normal elastic fiber consists of a central core and peripheral zone, in which the latter has small aggregates of 10 nm microfibrils. By the QF-DE method, globular structures consisting of numerous fibrils (5-20 nm in width) were observed between the collagen bundles. We could confirm that they were microfibril-rich peripheral zones of elastofibroma fibers by comparing the replica membrane and conventional electron microscopy. One of the characteristics of elastofibroma fibers is that they are assumed to contain numerous microfibrils. Immunohistochemically, spindle tumor cells showed positive immunoreaction for vimentin, whereas alpha-smooth muscle actin, desmin, S-100 protein and CD34 showed negative immunoreaction. By conventional electron microscopy, the tumor cell had thin cytoplasmic processes, pinocytotic vesicles and prominent rough endoplasmic reticulum. Abundant intracytoplasmic filaments were observed in some tumor cells. Thick lamina-like structures along with their inner nuclear membrane were often observed in the tumor cell nuclei. The whole image of the tumor cell was considered to be a periosteal-derived cell, which would produce numerous microfibrils in the peripheral zone of elastofibroma fibers. This study indicated that the QF-DE method could be applied to the pathological diagnosis and analysis of pathomechanism, even for surgical specimens obtained from a patient.

A fluidic device for the controlled formation and real-time monitoring of soft membranes self-assembled at liquid interfaces.

PubMed

Mendoza-Meinhardt, Arturo; Botto, Lorenzo; Mata, Alvaro

2018-02-13

Membrane materials formed at the interface between two liquids have found applications in a large variety of technologies, from sensors to drug-delivery and catalysis. However, studying the formation of these membranes in real-time presents considerable challenges, owing to the difficulty of prescribing the location and instant of formation of the membrane, the difficulty of observing time-dependent membrane shape and thickness, and the poor reproducibility of results obtained using conventional mixing procedures. Here we report a fluidic device that facilitates characterisation of the time-dependent thickness, morphology and mass transport properties of materials self-assembled at fluid-fluid interfaces. In the proposed device the membrane forms from the controlled coalescence of two liquid menisci in a linear open channel. The linear geometry and controlled mixing of the solutions facilitate real-time visualisation, manipulation and improve reproducibility. Because of its small dimensions, the device can be used in conjunction with standard microscopy methods and reduces the required volumes of potentially expensive reagents. As an example application to tissue engineering, we use the device to characterise interfacial membranes formed by supra-molecular self-assembly of peptide-amphiphiles with either an elastin-like-protein or hyaluronic acid. The device can be adapted to study self-assembling membranes for applications that extend beyond bioengineering.

N-terminal domains of fibrillin 1 and fibrillin 2 direct the formation of homodimers: a possible first step in microfibril assembly.

PubMed Central

Trask, T M; Ritty, T M; Broekelmann, T; Tisdale, C; Mecham, R P

1999-01-01

Aggregation of fibrillin molecules via disulphide bonds is postulated to be an early step in microfibril assembly. By expressing fragments of fibrillin 1 and fibrillin 2 in a mammalian expression system, we found that the N-terminal region of each protein directs the formation of homodimers and that disulphide bonds stabilize this interaction. A large fragment of fibrillin 1 containing much of the region downstream from the N-terminus remained as a monomer when expressed in the same cell system, indicating that this region of the protein lacks dimerization domains. This finding also confirms that the overexpression of fibrillin fragments does not in itself lead to spurious dimer formation. Pulse-chase analysis demonstrated that dimer formation occurred intracellularly, suggesting that the process of fibrillin aggregation is initiated early after biosynthesis of the molecules. These findings also implicate the N-terminal region of fibrillin 1 and fibrillin 2 in directing the formation of a dimer intermediate that aggregates to form the functional microfibril. PMID:10359653

Effect of Intrinsic Twist on Length of Crystalline and Disordered Regions in Cellulose Microfibrils

NASA Astrophysics Data System (ADS)

Nili, Abdolmadjid; Shklyaev, Oleg; Zhao, Zhen; Zhong, Linghao; Crespi, Vincent

2013-03-01

Cellulose is the most abundant biological material in the world. It provides mechanical reinforcement for plant cell wall, and could potentially serve as renewable energy source for biofuel. Native cellulose forms a non-centrosymmetric chiral crystal due to lack of roto-inversion symmetry of constituent glucose chains. Chirality of cellulose crystal could result in an overall twist. Competition between unwinding torsional/extensional and twisting energy terms leads to twist induced frustration along fibril's axis. The accumulated frustration could be the origin of periodic disordered regions observed in cellulose microfibrils. These regions could play significant role in properties of cellulose bundles and ribbons as well as biological implications on plant cell walls. We propose a mechanical model based on Frenkel-Kontorova mechanism to investigate effects of radius dependent twist on crystalline size in cellulose microfibrils. Parameters of the model are adjusted according to all-atom molecular simulations. This work is supported by the US Department of Energy, Office of Basic Energy Sciences as part of The Center for LignoCellulose Structure and Formation, an Energy Frontier Research Center

Assembly and enlargement of the primary cell wall in plants

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1997-01-01

Growing plant cells are shaped by an extensible wall that is a complex amalgam of cellulose microfibrils bonded noncovalently to a matrix of hemicelluloses, pectins, and structural proteins. Cellulose is synthesized by complexes in the plasma membrane and is extruded as a self-assembling microfibril, whereas the matrix polymers are secreted by the Golgi apparatus and become integrated into the wall network by poorly understood mechanisms. The growing wall is under high tensile stress from cell turgor and is able to enlarge by a combination of stress relaxation and polymer creep. A pH-dependent mechanism of wall loosening, known as acid growth, is characteristic of growing walls and is mediated by a group of unusual wall proteins called expansins. Expansins appear to disrupt the noncovalent bonding of matrix hemicelluloses to the microfibril, thereby allowing the wall to yield to the mechanical forces generated by cell turgor. Other wall enzymes, such as (1-->4) beta-glucanases and pectinases, may make the wall more responsive to expansin-mediated wall creep whereas pectin methylesterases and peroxidases may alter the wall so as to make it resistant to expansin-mediated creep.

Assembly and enlargement of the primary cell wall in plants.

PubMed

Cosgrove, D J

1997-01-01

Growing plant cells are shaped by an extensible wall that is a complex amalgam of cellulose microfibrils bonded noncovalently to a matrix of hemicelluloses, pectins, and structural proteins. Cellulose is synthesized by complexes in the plasma membrane and is extruded as a self-assembling microfibril, whereas the matrix polymers are secreted by the Golgi apparatus and become integrated into the wall network by poorly understood mechanisms. The growing wall is under high tensile stress from cell turgor and is able to enlarge by a combination of stress relaxation and polymer creep. A pH-dependent mechanism of wall loosening, known as acid growth, is characteristic of growing walls and is mediated by a group of unusual wall proteins called expansins. Expansins appear to disrupt the noncovalent bonding of matrix hemicelluloses to the microfibril, thereby allowing the wall to yield to the mechanical forces generated by cell turgor. Other wall enzymes, such as (1-->4) beta-glucanases and pectinases, may make the wall more responsive to expansin-mediated wall creep whereas pectin methylesterases and peroxidases may alter the wall so as to make it resistant to expansin-mediated creep.

Induction and regulation of murine emphysema by elastin peptides.

PubMed

Sellami, Mehdi; Meghraoui-Kheddar, Aïda; Terryn, Christine; Fichel, Caroline; Bouland, Nicole; Diebold, Marie-Daniele; Guenounou, Moncef; Héry-Huynh, Stéphanie; Le Naour, Richard

2016-01-01

Emphysema is the major component of chronic obstructive pulmonary disease (COPD). During emphysema, elastin breakdown in the lung tissue originates from the release of large amounts of elastase by inflammatory cells. Elevated levels of elastin-derived peptides (EP) reflect massive pulmonary elastin breakdown in COPD patients. Only the EP containing the GXXPG conformational motif with a type VIII β-turn are elastin receptor ligands inducing biological activities. In addition, the COOH-terminal glycine residue of the GXXPG motif seems a prerequisite to the biological activity. In this study, we endotracheally instilled C57BL/6J mice with GXXPG EP and/or COOH-terminal glycine deleted-EP whose sequences were designed by molecular dynamics and docking simulations. We investigated their effect on all criteria associated with the progression of murine emphysema. Bronchoalveolar lavages were recovered to analyze cell profiles by flow cytometry and lungs were prepared to allow morphological and histological analysis by immunostaining and confocal microscopy. We observed that exposure of mice to EP elicited hallmark features of emphysema with inflammatory cell accumulation associated with increased matrix metalloproteinases and desmosine expression and of remodeling of parenchymal tissue. We also identified an inactive COOH-terminal glycine deleted-EP that retains its binding-activity to EBP and that is able to inhibit the in vitro and in vivo activities of emphysema-inducing EP. This study demonstrates that EP are key actors in the development of emphysema and that they represent pharmacological targets for an alternative treatment of emphysema based on the identification of EP analogous antagonists by molecular modeling studies. Copyright © 2016 the American Physiological Society.

Circulating Elastin Fragments Are Not Affected by Hepatic, Renal and Hemodynamic Changes, But Reflect Survival in Cirrhosis with TIPS.

PubMed

Nielsen, M J; Lehmann, J; Leeming, D J; Schierwagen, R; Klein, S; Jansen, C; Strassburg, C P; Bendtsen, F; Møller, S; Sauerbruch, T; Karsdal, M A; Krag, A; Trebicka, J

2015-11-01

Progressive fibrosis increases hepatic resistance and causes portal hypertension with complications. During progressive fibrosis remodeling and deposition of collagens and elastin occur. Elastin remodeling is crucially involved in fibrosis progression in animal models and human data. This study investigated the association of circulating elastin with the clinical outcome in cirrhotic patients with severe portal hypertension receiving transjugular intrahepatic porto-systemic shunt (TIPS). We analyzed portal and hepatic venous samples of 110 cirrhotic patients obtained at TIPS insertion and 2 weeks later. The circulating levels of elastin fragments (ELM) were determined using specific monoclonal ELISA. The relationship of ELM with clinical short-time follow-up and long-term outcome was investigated. Circulating levels of ELM showed a gradient across the liver before TIPS with higher levels in the hepatic vein. Interestingly, the circulating ELM levels remained unchanged after TIPS. The circulating levels of ELM in portal and hepatic veins correlated with platelet counts and inversely with serum sodium. Hepatic venous levels of ELM were higher in CHILD C compared to CHILD A and B and were associated with the presence of ascites. Patients with high levels of ELM in the hepatic veins before TIPS showed poorer survival. In multivariate analysis ELM levels in the hepatic veins and MELD were independent predictors of mortality in these patients. This study demonstrated that circulating levels of ELM are not associated with hemodynamic changes, but might reflect fibrosis remodeling and predict survival in patients with severe portal hypertension receiving TIPS independently of MELD.

The effect of oxidation on the mechanical response and microstructure of porcine aortas.

PubMed

Stephen, Elizabeth A; Venkatasubramaniam, Arundhathi; Good, Theresa A; Topoleski, L D Timmie

2014-09-01

Reactive oxygen species (ROS), a product of many cellular functions, has been implicated in many age-related pathophysiological processes, including cardiovascular disease. The arterial proteins collagen and elastin may also undergo structural and functional changes due to damage caused by ROS. This study examined the effect of oxidation on the mechanical response of porcine aortas and aorta elastin and the associated changes in structural protein ultrastructure as a step in exploring the role of molecular changes in structural proteins with aging on elastic artery function. We examined the change in mechanical properties of aorta samples after various oxidation times as a first step in understanding how the oxidative environment associated with aging could impact mechanical properties of arterial structural proteins. We used confocal microscopy to visualize how the microstructure of isolated elastin changed with oxidation. We find that short term oxidation of elastin isolated from aortas leads to an increase in material stiffness, but also an increase in the fiber diameter, increase in void space in the matrix, and a decrease in the fiber orientation, possibly due to fiber cross-linking. The short term effects of oxidation on arterial collagen is more complex, with increase in material stiffness seen in the collagen region of the stress stretch curve at low extents of oxidation, but not at high levels of oxidation. These results may provide insight into the relationship between oxidative damage to tissue associated with aging and disease, structure of the arterial proteins elastin and collagen, and arterial mechanical properties and function. © 2013 Wiley Periodicals, Inc.

Vascular lysyl oxidase over-expression alters extracellular matrix structure and induces oxidative stress.

PubMed

Varona, Saray; García-Redondo, Ana B; Martínez-González, Jose; Salaices, Mercedes; Briones, Ana M; Rodríguez, Cristina

Lysyl oxidase (LOX) participates in the assembly of collagen and elastin fibres. The impact of vascular LOX over-expression on extracellular matrix (ECM) structure and its contribution to oxidative stress has been analysed. Studies were conducted on mice over-expressing LOX (Tg), specifically in smooth muscle cells (VSMC). Gene expression was assessed by real-time PCR analysis. Sirius Red staining, H 2 O 2 production and NADPH oxidase activity were analysed in different vascular beds. The size and number of fenestra of the internal elastic lamina were determined by confocal microscopy. LOX activity was up-regulated in VSMC of transgenic mice compared with cells from control animals. At the same time, transgenic cells deposited more organised elastin fibres and their supernatants induced a stronger collagen assembly in in vitro assays. Vascular collagen cross-linking was also higher in Tg mice, which showed a decrease in the size of fenestrae and an enhanced expression of Fibulin-5. Interestingly, higher H 2 O 2 production and NADPH oxidase activity was detected in the vascular wall from transgenic mice. The H 2 O 2 scavenger catalase attenuated the stronger deposition of mature elastin fibres induced by LOX transgenesis. LOX over-expression in VSMC was associated with a change in the structure of collagen and elastin fibres. LOX could constitute a novel source of oxidative stress that might participate in elastin changes and contribute to vascular remodelling. Copyright © 2017 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

Elastin structure and its involvement in skin photoageing.

PubMed

Weihermann, A C; Lorencini, M; Brohem, C A; de Carvalho, C M

2017-06-01

Skin aging is a complex process that may be caused by factors that are intrinsic and extrinsic to the body. Ultraviolet (UV) radiation represents one of the main sources of skin damage over the years and characterizes a process known as photoaging. Among the changes that affect cutaneous tissue with age, the loss of elastic properties caused by changes in elastin production, increased degradation and/or processing produces a substantial impact on tissue esthetics and health. The occurrence of solar elastosis is one of the main markers of cutaneous photoaging and is characterized by disorganized and non-functional deposition of elastic fibers. The occurrence of UV radiation-induced alternative splicing of the elastin gene, which leads to inadequate synthesis of the proteins required for the correct assembly of elastic fibers, is a potential explanation for this phenomenon. Innovative studies have been fundamental for the elucidation of rarely explored photoaging mechanisms and have enabled the identification of effective therapeutic alternatives such as cosmetic products. This review addresses cutaneous photoaging and the changes that affect elastin in this process. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Age-related morphological changes of the dermal matrix in human skin documented in vivo by multiphoton microscopy

NASA Astrophysics Data System (ADS)

Wang, Hequn; Shyr, Thomas; Fevola, Michael J.; Cula, Gabriela Oana; Stamatas, Georgios N.

2018-03-01

Two-photon fluorescence (TPF) and second harmonic generation (SHG) microscopy provide direct visualization of the skin dermal fibers in vivo. A typical method for analyzing TPF/SHG images involves averaging the image intensity and therefore disregarding the spatial distribution information. The goal of this study is to develop an algorithm to document age-related effects of the dermal matrix. TPF and SHG images were acquired from the upper inner arm, volar forearm, and cheek of female volunteers of two age groups: 20 to 30 and 60 to 80 years of age. The acquired images were analyzed for parameters relating to collagen and elastin fiber features, such as orientation and density. Both collagen and elastin fibers showed higher anisotropy in fiber orientation for the older group. The greatest difference in elastin fiber anisotropy between the two groups was found for the upper inner arm site. Elastin fiber density increased with age, whereas collagen fiber density decreased with age. The proposed analysis considers the spatial information inherent to the TPF and SHG images and provides additional insights into how the dermal fiber structure is affected by the aging process.

On the occurrence of polyproline II structure in elastin

NASA Astrophysics Data System (ADS)

Martino, M.; Bavoso, A.; Guantieri, V.; Coviello, A.; Tamburro, A. M.

2000-02-01

To shed light on the occurrence of the polyproline II (PP II) structure in the elastomeric protein elastin, the octapeptide sequence ALGGGALG of the N-terminal region of human elastin was studied in its monomeric and polymeric form, both in solution and in the solid state. Furthermore, the polymer poly(PG), chosen by us as an a priori reference compound for investigating the stability of PP II structure in presence of alternating proline and glycine residues along the polypeptide chain, was studied by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Its "monomeric" form Boc-PG-OH, was also analyzed by X-ray diffraction. It was shown that, in the solid state the presence of PG or GGG sequences in polypeptide chains and even in a short peptide as Boc-PG-OH induces the acquisition of the PP II structural motif. However, in solution this conformation appears to be much more unstable even in the case of long polypeptide chains. The finding that at room temperature the PP II structure is always in equilibrium with other conformers suggests that its dynamics could also contribute to the molecular mechanism of elastin elasticity.

Structure and applications of a temperature responsive recombinant protein hydrogel based on silk- and elastin-like amino acid motifs

NASA Astrophysics Data System (ADS)

Drummy, Lawrence; Tomczak, Melanie; Macauliffe, Joseph; Vaia, Richard; Naik, Rajesh

2008-03-01

Proteins form the main components of many natural materials, and they can be designed to offer tailored functionality and material properties. Silk elastin-like proteins (SELP)s come from a family of repeat sequence protein polymers based on Bombyx mori silk and mammalian elastin that are recombinantly expressed in E. coli. SELP gels are formed by heating the protein solutions in order to induce physical crosslinking of the silk β-sheet regions, they contain approximately 80-90% water by weight and they can be used for encapsulation of enzymes or nanoparticles. For example, horseradish peroxidase demonstrates added resistance to drying and heat treatment when encapsulated in the gel matrix. During gel formation, small angle X-ray scattering shows intensity increases in two distinct regions of reciprocal space, one reversible with temperature and one irreversible. By fitting the scattering data to a unified power-law/Gunier model, morphological parameters are extracted. The thermally reversible intensity changes are attributed to a hydrophilic/hydrophobic transition in the elastin segments, while the irreversible intensity change is due to the crystalline regions formed by the silk blocks.

Role of fetal nutrient restriction and postnatal catch-up growth on structural and mechanical alterations of rat aorta.

PubMed

Gutiérrez-Arzapalo, Perla Y; Rodríguez-Rodríguez, Pilar; Ramiro-Cortijo, David; López de Pablo, Ángel L; López-Giménez, María Rosario; Condezo-Hoyos, Luis; Greenwald, Stephen E; González, Maria Del Carmen; Arribas, Silvia M

2017-12-26

Intrauterine growth restriction (IUGR), induced by maternal undernutrition, leads to impaired aortic development. This is followed by hypertrophic remodelling associated with accelerated growth during lactation. Fetal nutrient restriction is associated with increased aortic compliance at birth and at weaning, but not in adult animals. This mechanical alteration may be related to a decreased perinatal collagen deposition. Aortic elastin scaffolds purified from young male and female IUGR animals also exhibit increased compliance, only maintained in adult IUGR females. These mechanical alterations may be related to differences in elastin deposition and remodelling. Fetal undernutrition induces similar aortic structural and mechanical alterations in young male and female rats. Our data argue against an early mechanical cause for the sex differences in hypertension development induced by maternal undernutrition. However, the larger compliance of elastin in adult IUGR females may contribute to the maintenance of a normal blood pressure level. Fetal undernutrition programmes hypertension development, males being more susceptible. Deficient fetal elastogenesis and vascular growth is a possible mechanism. We investigated the role of aortic mechanical alterations in a rat model of hypertension programming, evaluating changes at birth, weaning and adulthood. Dams were fed ad libitum (Control) or 50% of control intake during the second half of gestation (maternal undernutrition, MUN). Offspring aged 3 days, 21 days and 6 months were studied. Blood pressure was evaluated in vivo. In the thoracic aorta we assessed gross structure, mechanical properties (intact and purified elastin), collagen and elastin content and internal elastic lamina (IEL) organization. Only adult MUN males developed hypertension (systolic blood pressure: MUN males  = 176.6 ± 5.6 mmHg; Control males  = 136.1 ± 4.9 mmHg). At birth MUN rats were lighter, with smaller aortic cross-sectional area (MUN males  = (1.51 ± 0.08) × 10 5  μm 2 , Control males  = (2.8 ± 0.04) × 10 5  μm 2 ); during lactation MUN males and females exhibited catch-up growth and aortic hypertrophy (MUN males  = (14.5 ± 0.5) × 10 5  μm 2 , Control males  = (10.4 ± 0.9) × 10 5  μm 2 ), maintained until adulthood. MUN aortas were more compliant until weaning (functional stiffness: MUN males  = 1.0 ± 0.04; Control males  = 1.3 ± 0.03), containing less collagen with larger IEL fenestrae, returning to normal in adulthood. Purified elastin from young MUN offspring was more compliant in both sexes; only MUN adult females maintained larger elastin compliance (slope: MUN females  = 24.1 ± 1.9; Control females  = 33.3 ± 2.8). Fetal undernutrition induces deficient aortic development followed by hypertrophic remodelling and larger aortic compliance in the perinatal period, with similar alterations in collagen and elastin in both sexes. The observed alterations argue against an initial mechanical cause for sex differences in hypertension development. However, the maintenance of high elastin compliance in adult females might protect them against blood pressure rise. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Multiscale approach including microfibril scale to assess elastic constants of cortical bone based on neural network computation and homogenization method.

PubMed

Barkaoui, Abdelwahed; Chamekh, Abdessalem; Merzouki, Tarek; Hambli, Ridha; Mkaddem, Ali

2014-03-01

The complexity and heterogeneity of bone tissue require a multiscale modeling to understand its mechanical behavior and its remodeling mechanisms. In this paper, a novel multiscale hierarchical approach including microfibril scale based on hybrid neural network (NN) computation and homogenization equations was developed to link nanoscopic and macroscopic scales to estimate the elastic properties of human cortical bone. The multiscale model is divided into three main phases: (i) in step 0, the elastic constants of collagen-water and mineral-water composites are calculated by averaging the upper and lower Hill bounds; (ii) in step 1, the elastic properties of the collagen microfibril are computed using a trained NN simulation. Finite element calculation is performed at nanoscopic levels to provide a database to train an in-house NN program; and (iii) in steps 2-10 from fibril to continuum cortical bone tissue, homogenization equations are used to perform the computation at the higher scales. The NN outputs (elastic properties of the microfibril) are used as inputs for the homogenization computation to determine the properties of mineralized collagen fibril. The mechanical and geometrical properties of bone constituents (mineral, collagen, and cross-links) as well as the porosity were taken in consideration. This paper aims to predict analytically the effective elastic constants of cortical bone by modeling its elastic response at these different scales, ranging from the nanostructural to mesostructural levels. Our findings of the lowest scale's output were well integrated with the other higher levels and serve as inputs for the next higher scale modeling. Good agreement was obtained between our predicted results and literature data. Copyright © 2013 John Wiley & Sons, Ltd.

Localization of Cell Wall Polysaccharides in Normal and Compression Wood of Radiata Pine: Relationships with Lignification and Microfibril Orientation1

PubMed Central

Donaldson, Lloyd A.; Knox, J. Paul

2012-01-01

The distribution of noncellulosic polysaccharides in cell walls of tracheids and xylem parenchyma cells in normal and compression wood of Pinus radiata, was examined to determine the relationships with lignification and cellulose microfibril orientation. Using fluorescence microscopy combined with immunocytochemistry, monoclonal antibodies were used to detect xyloglucan (LM15), β(1,4)-galactan (LM5), heteroxylan (LM10 and LM11), and galactoglucomannan (LM21 and LM22). Lignin and crystalline cellulose were localized on the same sections used for immunocytochemistry by autofluorescence and polarized light microscopy, respectively. Changes in the distribution of noncellulosic polysaccharides between normal and compression wood were associated with changes in lignin distribution. Increased lignification of compression wood secondary walls was associated with novel deposition of β(1,4)-galactan and with reduced amounts of xylan and mannan in the outer S2 (S2L) region of tracheids. Xylan and mannan were detected in all lignified xylem cell types (tracheids, ray tracheids, and thick-walled ray parenchyma) but were not detected in unlignified cell types (thin-walled ray parenchyma and resin canal parenchyma). Mannan was absent from the highly lignified compound middle lamella, but xylan occurred throughout the cell walls of tracheids. Using colocalization measurements, we confirmed that polysaccharides containing galactose, mannose, and xylose have consistent correlations with lignification. Low or unsubstituted xylans were localized in cell wall layers characterized by transverse cellulose microfibril orientation in both normal and compression wood tracheids. Our results support the theory that the assembly of wood cell walls, including lignification and microfibril orientation, may be mediated by changes in the amount and distribution of noncellulosic polysaccharides. PMID:22147521

The Structural Role of Elastic Fibers in the Cornea Investigated Using a Mouse Model for Marfan Syndrome

PubMed Central

White, Tomas L.; Lewis, Philip; Hayes, Sally; Fergusson, James; Bell, James; Farinha, Luis; White, Nick S.; Pereira, Lygia V.; Meek, Keith M.

2017-01-01

Purpose The presence of fibrillin-rich elastic fibers in the cornea has been overlooked in recent years. The aim of the current study was to elucidate their functional role using a mouse model for Marfan syndrome, defective in fibrillin-1, the major structural component of the microfibril bundles that constitute most of the elastic fibers. Methods Mouse corneas were obtained from animals with a heterozygous fibrillin-1 mutation (Fbn1+/−) and compared to wild type controls. Corneal thickness and radius of curvature were calculated using optical coherence tomography microscopy. Elastic microfibril bundles were quantified and visualized in three-dimensions using serial block face scanning electron microscopy. Transmission electron microscopy was used to analyze stromal ultrastructure and proteoglycan distribution. Center-to-center average interfibrillar spacing was determined using x-ray scattering. Results Fbn1+/− corneas were significantly thinner than wild types and displayed a higher radius of curvature. In the Fbn1+/− corneas, elastic microfibril bundles were significantly reduced in density and disorganized compared to wild-type controls, in addition to containing a higher average center-to-center collagen interfibrillar spacing in the center of the cornea. No other differences were detected in stromal ultrastructure or proteoglycan distribution between the two groups. Proteoglycan side chains appeared to colocalize with the microfibril bundles. Conclusions Elastic fibers have an important, multifunctional role in the cornea as highlighted by the differences observed between Fbn1+/− and wild type animals. We contend that the presence of normal quantities of structurally organized elastic fibers are required to maintain the correct geometry of the cornea, which is disrupted in Marfan syndrome. PMID:28395026

Hydrophobic drug-triggered self-assembly of nanoparticles from silk-elastin-like protein polymers for drug delivery.

PubMed

Xia, Xiao-Xia; Wang, Ming; Lin, Yinan; Xu, Qiaobing; Kaplan, David L

2014-03-10

Silk-elastin-like protein polymers (SELPs) combine the mechanical and biological properties of silk and elastin. These properties have led to the development of various SELP-based materials for drug delivery. However, SELPs have rarely been developed into nanoparticles, partially due to the complicated fabrication procedures, nor assessed for potential as an anticancer drug delivery system. We have recently constructed a series of SELPs (SE8Y, S2E8Y, and S4E8Y) with various ratios of silk to elastin blocks and described their capacity to form micellar-like nanoparticles upon thermal triggering. In this study, we demonstrate that doxorubicin, a hydrophobic antitumor drug, can efficiently trigger the self-assembly of SE8Y (SELPs with silk to elastin ratio of 1:8) into uniform micellar-like nanoparticles. The drug can be loaded in the SE8Y nanoparticles with an efficiency around 6.5% (65 ng doxorubicin/μg SE8Y), S2E8Y with 6%, and S4E8Y with 4%, respectively. In vitro studies with HeLa cell lines demonstrate that the protein polymers are not cytotoxic (IC50 > 200 μg/mL), while the doxorubicin-loaded SE8Y nanoparticles showed a 1.8-fold higher cytotoxicity than the free drug. Confocal laser scanning microscopy (CLSM) and flow cytometry indicate significant uptake of the SE8Y nanoparticles by the cells and suggest internalization of the nanoparticles through endocytosis. This study provides an all-aqueous, facile method to prepare nanoscale, drug-loaded SELPs packages with potential for tumor cell treatments.

Qualitative and quantitative assessment of collagen and elastin in annulus fibrosus of the physiologic and scoliotic intervertebral discs.

PubMed

Kobielarz, Magdalena; Szotek, Sylwia; Głowacki, Maciej; Dawidowicz, Joanna; Pezowicz, Celina

2016-09-01

The biophysical properties of the annulus fibrosus of the intervertebral disc are determined by collagen and elastin fibres. The progression of scoliosis is accompanied by a number of pathological changes concerning these structural proteins. This is a major cause of dysfunction of the intervertebral disc. The object of the study were annulus fibrosus samples excised from intervertebral discs of healthy subjects and patients treated surgically for scoliosis in the thoracolumbar or lumbar spine. The research material was subjected to structural analysis by light microscopy and quantitative analysis of the content of collagen types I, II, III and IV as well as elastin by immunoenzymatic test (ELISA). A statistical analysis was conducted to assess the impact of the sampling site (Mann-Whitney test, α=0.05) and scoliosis (Wilcoxon matched pairs test, α=0.05) on the obtained results. The microscopic studies conducted on scoliotic annulus fibrosus showed a significant architectural distortion of collagen and elastin fibres. Quantitative biochemical assays demonstrated region-dependent distribution of only collagen types I and II in the case of healthy intervertebral discs whereas in the case of scoliotic discs region-dependent distribution concerned all examined proteins of the extracellular matrix. Comparison of scoliotic and healthy annulus fibrosus revealed a significant decrease in the content of collagen type I and elastin as well as a slight increase in the proportion of collagen types III and IV. The content of collagen type II did not differ significantly between both groups. The observed anomalies are a manifestation of degenerative changes affecting annulus fibrosus of the intervertebral disc in patients suffering from scoliosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conformational dynamics of minimal elastin-like polypeptides: the role of proline revealed by molecular dynamics and nuclear magnetic resonance.

PubMed

Glaves, Rachel; Baer, Marcel; Schreiner, Eduard; Stoll, Raphael; Marx, Dominik

2008-12-22

Previous molecular dynamics studies of the elastin-like peptide (ELP) GVG(VPGVG) predict that this ELP undergoes a conformational transition from an open to a more compact closed state upon an increase in temperature. These structural changes occurring in this minimal elastin model at the so-called inverse temperature transition (ITT), which takes place when elastin is heated to temperatures of about 20-40 (omicron)C, are investigated further in this work by means of a combined theoretical and experimental approach. To do this, additional extensive classical molecular dynamics (MD) simulations of the capped octapeptide are carried out, analyzed, and compared to data obtained from homonuclear magnetic resonance (NMR) spectroscopy of the same octapeptide. Moreover, in the previous simulations, the proline residue in the ELP is found to act as a hinge, thereby allowing for the large-amplitude opening and closing conformational motion of the ITT. To explore the role of proline in such elastin repeating units, a point mutant (P5I), which replaces the proline residue with an isoleucine residue, is also investigated using the aforementioned theoretical and experimental techniques. The results show that the site-directed mutation completely alters the properties of this ELP, thus confirming the importance of the highly conserved proline residue in the ITT. Furthermore, a correlation between the two different methods employed is seen. Both methods predict the mutant ELP to be present in an unstructured form and the wild type ELP to have a beta-turn-like structure. Finally, the role of the peptidyl cis to trans isomerization of the proline hinge is assessed in detail.

Use of versican variant V3 and versican antisense expression to engineer cultured human skin containing increased content of insoluble elastin.

PubMed

Merrilees, Mervyn J; Falk, Ben A; Zuo, Ning; Dickinson, Michelle E; May, Barnaby C H; Wight, Thomas N

2017-01-01

Skin substitutes for repair of dermal wounds are deficient in functional elastic fibres. We report that the content of insoluble elastin in the dermis of cultured human skin can be increased though the use of two approaches that enhance elastogenesis by dermal fibroblasts, forced expression of versican variant V3, which lacks glycosaminoglycan (GAG) chains, and forced expression of versican antisense to decrease levels of versican variant V1 with GAG chains. Human dermal fibroblasts transduced with V3 or anti-versican were cultured under standard conditions over a period of 4 weeks to produce dermal sheets, with growth enhanced though multiple seedings for the first 3 weeks. Human keratinocytes, cultured in supplemented media, were added to the 4-week dermal sheets and the skin layer cultured for a further week. At 5 weeks, keratinocytes were multilayered and differentiated, with desmosome junctions thoughout and keratin deposits in the upper squamous layers. The dermal layer was composed of layered fibroblasts surrounded by extracellular matrix of collagen bundles and, in control cultures, small scattered elastin deposits. Forced expression of V3 and versican antisense slowed growth, decreased versican V1 expression, increased tropoelastin expression and/or the deposition of large aggregates of insoluble elastin in the dermal layer, and increased tissue stiffness, as measured by nano-indentation. Skin sheets were also cultured on Endoform Dermal Template™, the biodegradable wound dressing made from the lamina propria of sheep foregut. Skin structure and the enhanced deposition of elastin by forced expression of V3 and anti-versican were preserved on this supportive substrate. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Spontaneous aortic dissecting hematoma in two dogs.

PubMed

Boulineau, Theresa Marie; Andrews-Jones, Lydia; Van Alstine, William

2005-09-01

This report describes 2 cases of spontaneous aortic dissecting hematoma in young Border Collie and Border Collie crossbred dogs. Histology was performed in one of the cases involving an unusual splitting of the elastin present within the wall of the aorta, consistent with elastin dysplasia as described in Marfan syndrome in humans. The first case involved a young purebred Border Collie that died suddenly and the second case involved a Border Collie crossbred dog that died after a 1-month history of seizures. Gross lesions included pericardial tamponade with dissection of the ascending aorta in the former case and thoracic cavity hemorrhage, mediastinal hematoma, and aortic dissection in the latter. Histologic lesions in the case of the Border Collie crossbred dog included a dissecting hematoma of the ascending aorta with elastin dysplasia and right axillary arterial intimal proliferation.

Applications of elastin-like polypeptides in drug delivery

PubMed Central

MacEwan, Sarah R; Chilkoti, Ashutosh

2014-01-01

Elastin-like polypeptides (ELPs) are biopolymers inspired by human elastin. Their lower critical solution temperature phase transition behavior and biocompatibility make them useful materials for stimulus-responsive applications in biological environments. Due to their genetically encoded design and recombinant synthesis, the sequence and size of ELPs can be exactly defined. These design parameters control the structure and function of the ELP with a precision that is unmatched by synthetic polymers. Due to these attributes, ELPs have been used extensively for drug delivery in a variety of different embodiments—as soluble macromolecular carriers, self-assembled nanoparticles, cross-linked microparticles, or thermally coacervated depots. These ELP systems have been used to deliver biologic therapeutics, radionuclides, and small molecule drugs to a variety of anatomical sites for the treatment of diseases including cancer, type 2 diabetes, osteoarthritis, and neuroinflammation. PMID:24979207

Hydrogen-Bonding Network and OH Stretch Vibration of Cellulose: Comparison of Computational Modeling with Polarized IR and SFG Spectra.

PubMed

Lee, Christopher M; Kubicki, James D; Fan, Bingxin; Zhong, Linghao; Jarvis, Michael C; Kim, Seong H

2015-12-10

Hydrogen bonds play critical roles in noncovalent directional interactions determining the crystal structure of cellulose. Although diffraction studies accurately determined the coordinates of carbon and oxygen atoms in crystalline cellulose, the structural information on hydrogen atoms involved in hydrogen-bonding is still elusive. This could be complemented by vibrational spectroscopy; but the assignment of the OH stretch peaks has been controversial. In this study, we performed calculations using density functional theory with dispersion corrections (DFT-D2) for the cellulose Iβ crystal lattices with the experimentally determined carbon and oxygen coordinates. DFT-D2 calculations revealed that the OH stretch vibrations of cellulose are highly coupled and delocalized through intra- and interchain hydrogen bonds involving all OH groups in the crystal. Additionally, molecular dynamics (MD) simulations of a single cellulose microfibril showed that the conformations of OH groups exposed at the microfibril surface are not well-defined. Comparison of the computation results with the experimentally determined IR dichroism of uniaxially aligned cellulose microfibrils and the peak positions of various cellulose crystals allowed unambiguous identification of OH stretch modes observed in the vibrational spectra of cellulose.

The stability of cellulose: a statistical perspective from a coarse-grained model of hydrogen-bond networks.

PubMed

Shen, Tongye; Gnanakaran, S

2009-04-22

A critical roadblock to the production of biofuels from lignocellulosic biomass is the efficient degradation of crystalline microfibrils of cellulose to glucose. A microscopic understanding of how different physical conditions affect the overall stability of the crystalline structure of microfibrils could facilitate the design of more effective protocols for their degradation. One of the essential physical interactions that stabilizes microfibrils is a network of hydrogen (H) bonds: both intrachain H-bonds between neighboring monomers of a single cellulose polymer chain and interchain H-bonds between adjacent chains. We construct a statistical mechanical model of cellulose assembly at the resolution of explicit hydrogen-bond networks. Using the transfer matrix method, the partition function and the subsequent statistical properties are evaluated. With the help of this lattice-based model, we capture the plasticity of the H-bond network in cellulose due to frustration and redundancy in the placement of H-bonds. This plasticity is responsible for the stability of cellulose over a wide range of temperatures. Stable intrachain and interchain H-bonds are identified as a function of temperature that could possibly be manipulated toward rational destruction of crystalline cellulose.

Differential wall growth in gravistimulated corn roots: Its timing and regulation

NASA Technical Reports Server (NTRS)

Serlin, B. S.

1985-01-01

The experiments designed to document cell-wall level changes which occur as a result of their gravistimulation are described. The goal of this research is to elucidate the mechanism and time frame of differential growth following a controlled gravistimulation. To achieve this, rates of wall deposition will be determined by following the incorporation of radioactive monosaccharides into the wall. Complementing this experiment will be a freeze-etch study directed at revealing the spatial arrangment of both newly-deposited microfibrils and microfibrils that were present in the growing root prior to stimulation. The second phase of the proposed research will examine the roles ethylene and Ca(2+) have in the modulation of differential wall changes during gravitropism. Ethylene and Ca(2+) have both been implicated as regulators of the gravitropic response in roots and they have also been implicated as regulators of the gravitropic response in roots and they have also been reported to exert some control on the orientation of microfibrils. Both of these agents will be manipulated in such a way as to reveal whether they have a direct influence on cell wall deposition and microfibrillar alignment during the geotropic response.

Onion epidermis as a new model to study the control of growth anisotropy in higher plants.

PubMed

Suslov, Dmitry; Verbelen, Jean-Pierre; Vissenberg, Kris

2009-01-01

To elucidate the role of cellulose microfibrils in the control of growth anisotropy, a link between their net orientation, in vitro cell wall extensibility, and anisotropic cell expansion was studied during development of the adaxial epidermis of onion (Allium cepa) bulb scales using polarization confocal microscopy, creep tests, and light microscopy. During growth the net cellulose alignment across the whole thickness of the outer epidermal wall changed from transverse through random to longitudinal and back to transverse relative to the bulb axis. Cell wall extension in vitro was always higher transverse than parallel to the net cellulose alignment. The direction of growth anisotropy was perpendicular to the net microfibril orientation and changed during development from longitudinal to transverse to the bulb axis. The correlation between the degree of growth anisotropy and the net cellulose alignment was poor. Thus the net cellulose microfibril orientation across the whole thickness of the outer periclinal epidermis wall defines the direction but not the degree of growth anisotropy. Strips isolated from the epidermis in the directions perpendicular and transverse to a net cellulose orientation can be used as an extensiometric model to prove a protein involvement in the control of growth anisotropy.

Chapter 4. Cytomechanics of hair basics of the mechanical stability.

PubMed

Popescu, Crisan; Höcker, Hartwig

2009-01-01

Hair is a complex "cornified" multicellular tissue composed of cuticle and cortex cells mechanically acting as a whole. The cuticle cells overlap and cortex cells interdigitate, all cells being composed of different morphological elements and separated by the cell membrane complex (CMC). The CMC and the morphological elements of the cortex cells, the macrofibrils, composed of microfibrils or intermediate filaments (IFs), and the intermacrofibrillar and intermicrofibrillar cement or the amorphous matrix material determine the mechanical properties of hair. The IFs consist of alpha-keratin molecules being arranged in a sophisticated way of two parallel monomers and antiparallel and shifted dimers rationalized by the amino acid composition and sequence. The mechanical properties of hair result from mechanical interlocking effects, hydrophobic effects, hydrogen bridges, Coulombic interactions, and (covalent) isodipeptide and, in particular, disulfide bridges on a molecular level. The mechanical models applied to hair are based on a simple two-component system, the microfibril/matrix structure. An important regime of the stress-strain curve is the transition of the molecules of the microfibrils from the alpha-helical to the beta-sheet structure. Due to the longitudinal orientation of the IF molecules the longitudinal swelling of the fibers in water is negligible, the radial swelling, however, is substantial.

Elastin: a possible genetic biomarker for more severe ligament injuries in elite soccer. A pilot study

PubMed Central

Artells, Rosa; Pruna, Ricard; Dellal, Alexandre; Maffulli, Nicola

2016-01-01

Summary Background The study of new genetic biomarkers in genes related to connective tissue repair and regeneration may help to identify individuals with greater predisposition to injury, who may benefit from targeted preventive measures, and those who require longer recovery time following a muscle, ligament or tendon injury. The present study investigated whether single nucleotide polymorphisms of the Elastin gene could be related to MCL injury. Methods 60 top class football players were studied to identify single nucleotide polymorphisms for the Elastin (ELN) gene using Allelic Discrimination analysis. Each player was followed for 7 seasons, and each MCL injury was noted. Results Ligament injury rate, severity and recovery time are related to specific genotypes observed in the elastin gene, especially the ELN-AA (16 MCL) and the ELN-AG (3 MCL). Players with the ELN-GG genotype sustained no MCL injury during the 7 seasons of the study. Conclusions The identification of polymorphisms in the ELN gene may be used as a novel tool to better define an athlete’s genotype, and help to plan training and rehabilitation programmes to prevent or minimize MCL ligament injuries, and optimize the therapeutic and rehabilitation process after soft tissue injuries, and manage the workloads during trainings and matches. PMID:27900291

Three dimensional microstructural network of elastin, collagen, and cells in Achilles tendons.

PubMed

Pang, Xin; Wu, Jian-Ping; Allison, Garry T; Xu, Jiake; Rubenson, Jonas; Zheng, Ming-Hao; Lloyd, David G; Gardiner, Bruce; Wang, Allan; Kirk, Thomas Brett

2017-06-01

Similar to most biological tissues, the biomechanical, and functional characteristics of the Achilles tendon are closely related to its composition and microstructure. It is commonly reported that type I collagen is the predominant component of tendons and is mainly responsible for the tissue's function. Although elastin has been found in varying proportions in other connective tissues, previous studies report that tendons contain very small quantities of elastin. However, the morphology and the microstructural relationship among the elastic fibres, collagen, and cells in tendon tissue have not been well examined. We hypothesize the elastic fibres, as another fibrillar component in the extracellular matrix, have a unique role in mechanical function and microstructural arrangement in Achilles tendons. It has been shown that elastic fibres present a close connection with the tenocytes. The close relationship of the three components has been revealed as a distinct, integrated and complex microstructural network. Notably, a "spiral" structure within fibril bundles in Achilles tendons was observed in some samples in specialized regions. This study substantiates the hierarchical system of the spatial microstructure of tendon, including the mapping of collagen, elastin and tenocytes, with 3-dimensional confocal images. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1203-1214, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Double-hydrophobic elastin-like polypeptides with added functional motifs: Self-assembly and cytocompatibility.

PubMed

Le, Duc H T; Tsutsui, Yoko; Sugawara-Narutaki, Ayae; Yukawa, Hiroshi; Baba, Yoshinobu; Ohtsuki, Chikara

2017-09-01

We have recently developed a novel double-hydrophobic elastin-like triblock polypeptide called GPG, designed after the uneven distribution of two different hydrophobic domains found in elastin, an extracellular matrix protein providing elasticity and resilience to tissues. Upon temperature trigger, GPG undergoes a sequential self-assembling process to form flexible beaded nanofibers with high homogeneity and excellent dispersibility in water. Given that GPG might be a potential elastin-mimetic material, we sought to explore the biological activities of this block polypeptide. Besides GPG, several functionalized derivatives were also constructed by fusing functional motifs such as KAAK or KAAKGRGDS at the C-terminal of GPG. Although the added motifs affected the kinetics of fiber formation and β-sheet contents, all three GPGs assembled into beaded nanofibers at the physiological temperature. The resulting GPG nanofibers preserved their beaded structures in cell culture medium; therefore, they were coated on polystyrene substrates to study their cytocompatibility toward mouse embryonic fibroblasts, NIH-3T3. Among the three polypeptides, GPG having the cell-binding motif GRGDS derived from fibronectin showed excellent cell adhesion and cell proliferation properties compared to other conventional materials, suggesting its promising applications as extracellular matrices for mammalian cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2475-2484, 2017. © 2017 Wiley Periodicals, Inc.

Multiscale mechanical integrity of human supraspinatus tendon in shear after elastin depletion.

PubMed

Fang, Fei; Lake, Spencer P

2016-10-01

Human supraspinatus tendon (SST) exhibits region-specific nonlinear mechanical properties under tension, which have been attributed to its complex multiaxial physiological loading environment. However, the mechanical response and underlying multiscale mechanism regulating SST behavior under other loading scenarios are poorly understood. Furthermore, little is known about the contribution of elastin to tendon mechanics. We hypothesized that (1) SST exhibits region-specific shear mechanical properties, (2) fiber sliding is the predominant mode of local matrix deformation in SST in shear, and (3) elastin helps maintain SST mechanical integrity by facilitating force transfer among collagen fibers. Through the use of biomechanical testing and multiphoton microscopy, we measured the multiscale mechanical behavior of human SST in shear before and after elastase treatment. Three distinct SST regions showed similar stresses and microscale deformation. Collagen fiber reorganization and sliding were physical mechanisms observed as the SST response to shear loading. Measures of microscale deformation were highly variable, likely due to a high degree of extracellular matrix heterogeneity. After elastase treatment, tendon exhibited significantly decreased stresses under shear loading, particularly at low strains. These results show that elastin contributes to tendon mechanics in shear, further complementing our understanding of multiscale tendon structure-function relationships. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of a nonlinear fiber-optic spectrometer for human lung tissue exploration

PubMed Central

Peyrot, Donald A.; Lefort, Claire; Steffenhagen, Marie; Mansuryan, Tigran; Ducourthial, Guillaume; Abi-Haidar, Darine; Sandeau, Nicolas; Vever-Bizet, Christine; Kruglik, Sergei G.; Thiberville, Luc; Louradour, Frédéric; Bourg-Heckly, Geneviève

2012-01-01

Several major lung pathologies are characterized by early modifications of the extracellular matrix (ECM) fibrillar collagen and elastin network. We report here the development of a nonlinear fiber-optic spectrometer, compatible with an endoscopic use, primarily intended for the recording of second-harmonic generation (SHG) signal of collagen and two-photon excited fluorescence (2PEF) of both collagen and elastin. Fiber dispersion is accurately compensated by the use of a specific grism-pair stretcher, allowing laser pulse temporal width around 70 fs and excitation wavelength tunability from 790 to 900 nm. This spectrometer was used to investigate the excitation wavelength dependence (from 800 to 870 nm) of SHG and 2PEF spectra originating from ex vivo human lung tissue samples. The results were compared with spectral responses of collagen gel and elastin powder reference samples and also with data obtained using standard nonlinear microspectroscopy. The excitation-wavelength-tunable nonlinear fiber-optic spectrometer presented in this study allows performing nonlinear spectroscopy of human lung tissue ECM through the elastin 2PEF and the collagen SHG signals. This work opens the way to tunable excitation nonlinear endomicroscopy based on both distal scanning of a single optical fiber and proximal scanning of a fiber-optic bundle. PMID:22567579

One-stage Reconstruction of Soft Tissue Defects with the Sandwich Technique: Collagen-elastin Dermal Template and Skin Grafts

PubMed Central

Wollina, Uwe

2011-01-01

Background: A full-thickness soft tissue defect closure often needs complex procedures. The use of dermal templates can be helpful in improving the outcome. Objective: The objective was to evaluate a sandwich technique combining the dermal collagen–elastin matrix with skin grafts in a one-stage procedure. Materials and Methods: Twenty-three patients with 27 wounds were enrolled in this prospective single-centre observational study. The mean age was 74.8 ± 17.2 years. Included were full-thickness defects with exposed bone, cartilage and/ or tendons. The dermal collagen–elastin matrix was applied onto the wound bed accomplished by skin transplants, i.e. ‘sandwich’ transplantation. In six wounds, the transplants were treated with intermittent negative pressure therapy. Results: The size of defects was ≤875 cm2. The use of the dermal template resulted in a complete and stable granulation in 100% of wounds. Seventeen defects showed a complete closure and 19 achieved a complete granulation with an incomplete closure. There was a marked pain relief. No adverse events were noted due to the dermal template usage. Conclusions: Sandwich transplantation with the collagen–elastin matrix is a useful tool when dealing with full-thickness soft tissue defects with exposed bone, cartilage or tendons. PMID:22279382

Numerical model study of radio frequency vessel sealing thermodynamics

NASA Astrophysics Data System (ADS)

Pearce, John

2015-03-01

Several clinically successful clinical radio frequency vessel-sealing devices are currently available. The dominant thermodynamic principles at work involve tissue water vaporization processes. It is necessary to thermally denature vessel collagen, elastin and their adherent proteins to achieve a successful fusion. Collagens denature at middle temperatures, between about 60 and 90 C depending on heating time and rate. Elastin, and its adherent proteins, are more thermally robust, and require temperatures in excess of the boiling point of water at atmospheric pressure to thermally fuse. Rapid boiling at low apposition pressures leads to steam vacuole formation, brittle tissue remnants and frequently to substantial disruption in the vessel wall, particularly in high elastin-content arteries. High apposition pressures substantially increase the equilibrium boiling point of tissue water and are necessary to ensure a high probability of a successful seal. The FDM numerical models illustrate the beneficial effects of high apposition pressures.

[A turning point in the knowledge of the structure-function-activity relations of elastin].

PubMed

Alix, A J

2001-01-01

In this review are presented the last new results of our research group dealing with the molecular structures (atomic level) of tropoelastin, elastin and elastin derived peptides studied by using essentially methods of bioinformatics (theoretical predictions and molecular modelling) linked to experimental circular dichroism spectroscopic studies. We already had characterized both the local secondary structure and some parts of the tertiary structure of the tropoelastin and elastin molecules (human, bovine...), by using either theoretical predictions (local secondary structure, linear epitopes...) and/or experimental data (optical spectroscopic methods: Raman scattering, infrared absorption, circular dichroism). Except the cross-linking regions which are in helical conformations, the whole tropoelastin structure displays a lot of beta-reverse turns which usually belong to irregular structures in proteins. These turns play a key role in other regularly structures orientation (alpha-helix, beta-strand), thus they are very important in the native protein 3D architecture. It is particularly true for human tropoelastin, because its sequence is rich in glycines and prolines, and these residues are frequently met in beta-turns (a beta-turn is made of four consecutive residues which are stabilized by an hydrogen bond). Several types of beta-turns can be defined with the dihedral angles values phi and psi of the two central residues. Thus, by using a very recent updated set of propensities for the amino acid residues to belong to given types of reverse beta-turns (extracted from a reference set of known 3-D structures of globular proteins), we have determined, (by using our home made software COUDES), for all possible tetrapeptides of the human tropoelastin sequence, the distribution and the characterization of the possible type of turns. Thus, it is shown that the locations and/or the types of these reverse beta-turns reveal a regularity and are not all random. This confirms our hypothesis that intra-molecular elasticity of tropoelastin could be explained by the possibility of transitions between conformations involving short beta-strands and beta-turns. This result is of great interest in the construction (by using molecular biology) of elastic biomaterials derived from the elastin sequence (particularly, the elastin derived peptides corresponding to the sequence exon 21--(exon 24--exon 24...). Our study permit also to predict the conformations of specific elastin derived peptides which could have interesting biological activity. Peptides resulting from the degradation of elastin, the insoluble polymer of tropoelastin and responsible for the elasticity of vertebrate tissues, can induce biological effects and notably the regulation of matrix metalloproteinases (MMP-s) activity. Recently, it was proposed that some elastin derived hexapeptides resulting from circular permutations of VGVAPG (a three fold repetition sequence in exon 24 of human tropoelastin) possess MMP-1 production and activation regulation properties. This effect depends on the presence of the tropoelastin specific membraneous receptor 67 KDa EBP (Elastin Binding Protein). Our results obtained by using both circular dichroism spectroscopy and linear predictions confirmed the hypothesis of a structure dependent mechanism with a possibly occurring type VIII beta-turn on the first four residues of the GXXPG sequence consensus which is only present among all active peptides. Thus, we have performed extensive molecular dynamics studies, in both implicit and explicit solvent, on these active and inactive elastin derived hexapeptides. Using our own analysis method of pattern recognition of the types of the beta-reverse-turns followed during the molecular dynamics trajectory, we found that active and inactive peptides effectively form two well distinct conformational groups in which active peptides preferentially adopt conformation close to type VIII GXXP (beta-reverse-turn. The structural role of the C terminal G residue could also be explained. Additional molecular simulations on (VGVAPG)2 and (VGVAPG)3 show the formation of two or three GXXP tetrapeptides adopting a structure close to type VIII beta-reverse-turn, suggesting a local conformational preference for this motif. This observation of a specific structural single and/or repeated motif is in agreement with the circular dichroism spectra of the involved (VGVAPG)1, (VGVAPG)2 and (VGVAPG)3 peptides and then it can be proposed that their biological activities have to be linear. The final aim of this type of work is to understand more about the sequence/structure/function/activity relationships of those structured peptides in order to propose specific sequences (corresponding to specific structures) for best biological activity results.

2Q NMR of 2H2O ordering at solid interfaces

NASA Astrophysics Data System (ADS)

Krivokhizhina, Tatiana V.; Wittebort, R. J.

2014-06-01

Solvent ordering at an interface can be studied by multiple-quantum NMR. Quantitative studies of 2H2O ordering require clean double-quantum (2Q) filtration and an analysis of 2Q buildup curves that accounts for relaxation and, if randomly oriented samples are used, the distribution of residual couplings. A pulse sequence with absorption mode detection is extended for separating coherences by order and measuring relaxation times such as the 2Q filtered T2. Coherence separation is used to verify 2Q filtration and the 2Q filtered T2 is required to extract the coupling from the 2Q buildup curve when it is unresolved. With our analysis, the coupling extracted from the buildup curve in 2H2O hydrated collagen was equivalent to the resolved coupling measured in the usual 1D experiment and the 2Q to 1Q signal ratio was in accord with theory. Application to buildup curves from 2H2O hydrated elastin, which has an unresolved coupling, revealed a large increase in the 2Q signal upon mechanical stretch that is due to an increase in the ordered water fraction while changes in the residual coupling and T2 are small.

The effect of a collagen-elastin matrix on adhesion formation after flexor tendon repair in a rabbit model.

PubMed

Wichelhaus, Dagmar Alice; Beyersdoerfer, Sascha Tobias; Gierer, Philip; Vollmar, Brigitte; Mittlmeier, Th

2016-07-01

The outcome of flexor tendon surgery is negatively affected by the formation of adhesions which can occur during the healing of the tendon repair. In this experimental study, we sought to prevent adhesion formation by wrapping a collagen-elastin scaffold around the repaired tendon segment. In 28 rabbit hind legs, the flexor tendons of the third and fourth digits were cut and then repaired using a two-strand suture technique on the fourth digit and a four-strand technique on the third digit. Rabbits were randomly assigned to study and control groups. In the control group, the operation ended by closing the tendon sheath and the skin. In the study group, a collagen-elastin scaffold was wrapped around the repaired tendon segment in both digits. After 3 and 8 weeks, the tendons were harvested and processed histologically. The range of motion of the digits and the gap formation between the repaired tendon ends were measured. The formation of adhesions, infiltration of leucocytes and extracellular inflammatory response were quantified. At the time of tendon harvesting, all joints of the operated toes showed free range of motion. Four-strand core sutures lead to significantly less diastasis between the repaired tendon ends than two-strand core suture repairs. The collagen-elastin scaffold leads to greater gapping after 3 weeks compared to the controls treated without the matrix. Within the tendons treated with the collagen-elastin matrix, a significant boost of cellular and extracellular inflammation could be stated after 3 weeks which was reflected by a higher level of CAE positive cells and more formation of myofibroblasts in the αSMA stain in the study group. The inflammatory response subsided gradually and significantly until the late stage of the study. Both the cellular and extracellular inflammatory response was emphasized with the amount of material used for the repair. The use of a collagen-elastin matrix cannot be advised for the prevention of adhesion formation in flexor tendon surgery, because it enhances both cellular and extracellular inflammation. Four-strand core sutures lead to less gapping than two-strand core sutures, but at the same time, the cellular and extracellular inflammatory response is more pronounced.

Mitochondria-targeted antioxidant therapy with MitoQ ameliorates aortic stiffening in old mice.

PubMed

Gioscia-Ryan, Rachel A; Battson, Micah L; Cuevas, Lauren M; Eng, Jason S; Murphy, Michael P; Seals, Douglas R

2018-05-01

Aortic stiffening is a major independent risk factor for cardiovascular diseases, cognitive dysfunction, and other chronic disorders of aging. Mitochondria-derived reactive oxygen species are a key source of arterial oxidative stress, which may contribute to arterial stiffening by promoting adverse structural changes-including collagen overabundance and elastin degradation-and enhancing inflammation, but the potential for mitochondria-targeted therapeutic strategies to ameliorate aortic stiffening with primary aging is unknown. We assessed aortic stiffness [pulse-wave velocity (aPWV)], ex vivo aortic intrinsic mechanical properties [elastic modulus (EM) of collagen and elastin regions], and aortic protein expression in young (~6 mo) and old (~27 mo) male C57BL/6 mice consuming normal drinking water (YC and OC) or water containing mitochondria-targeted antioxidant MitoQ (250 µM; YMQ and OMQ) for 4 wk. Both baseline and postintervention aPWV values were higher in OC vs. YC (post: 482 ± 21 vs. 420 ± 5 cm/s, P < 0.05). MitoQ had no effect in young mice but decreased aPWV in old mice (OMQ, 426 ± 20, P < 0.05 vs. OC). MitoQ did not affect age-associated increases in aortic collagen-region EM, collagen expression, or proinflammatory cytokine expression, but partially attenuated age-associated decreases in elastin region EM and elastin expression. Our results demonstrate that MitoQ reverses in vivo aortic stiffness in old mice and suggest that mitochondria-targeted antioxidants may represent a novel, promising therapeutic strategy for decreasing aortic stiffness with primary aging and, possibly, age-related clinical disorders in humans. The destiffening effects of MitoQ treatment may be at least partially mediated by attenuation/reversal of age-related aortic elastin degradation. NEW & NOTEWORTHY We show that 4 wk of treatment with the mitochondria-specific antioxidant MitoQ in mice completely reverses the age-associated elevation in aortic stiffness, assessed as aortic pulse-wave velocity. The destiffening effects of MitoQ treatment may be at least partially mediated by attenuation of age-related aortic elastin degradation. Our results suggest that mitochondria-targeted therapeutic strategies may hold promise for decreasing arterial stiffening with aging in humans, possibly decreasing the risk of many chronic age-related clinical disorders.

Mitochondria-targeted antioxidant therapy with MitoQ ameliorates aortic stiffening in old mice

PubMed Central

Gioscia-Ryan, Rachel A.; Battson, Micah L.; Cuevas, Lauren M.; Eng, Jason S.; Murphy, Michael P.

2018-01-01

Aortic stiffening is a major independent risk factor for cardiovascular diseases, cognitive dysfunction, and other chronic disorders of aging. Mitochondria-derived reactive oxygen species are a key source of arterial oxidative stress, which may contribute to arterial stiffening by promoting adverse structural changes—including collagen overabundance and elastin degradation—and enhancing inflammation, but the potential for mitochondria-targeted therapeutic strategies to ameliorate aortic stiffening with primary aging is unknown. We assessed aortic stiffness [pulse-wave velocity (aPWV)], ex vivo aortic intrinsic mechanical properties [elastic modulus (EM) of collagen and elastin regions], and aortic protein expression in young (~6 mo) and old (~27 mo) male C57BL/6 mice consuming normal drinking water (YC and OC) or water containing mitochondria-targeted antioxidant MitoQ (250 µM; YMQ and OMQ) for 4 wk. Both baseline and postintervention aPWV values were higher in OC vs. YC (post: 482 ± 21 vs. 420 ± 5 cm/s, P < 0.05). MitoQ had no effect in young mice but decreased aPWV in old mice (OMQ, 426 ± 20, P < 0.05 vs. OC). MitoQ did not affect age-associated increases in aortic collagen-region EM, collagen expression, or proinflammatory cytokine expression, but partially attenuated age-associated decreases in elastin region EM and elastin expression. Our results demonstrate that MitoQ reverses in vivo aortic stiffness in old mice and suggest that mitochondria-targeted antioxidants may represent a novel, promising therapeutic strategy for decreasing aortic stiffness with primary aging and, possibly, age-related clinical disorders in humans. The destiffening effects of MitoQ treatment may be at least partially mediated by attenuation/reversal of age-related aortic elastin degradation. NEW & NOTEWORTHY We show that 4 wk of treatment with the mitochondria-specific antioxidant MitoQ in mice completely reverses the age-associated elevation in aortic stiffness, assessed as aortic pulse-wave velocity. The destiffening effects of MitoQ treatment may be at least partially mediated by attenuation of age-related aortic elastin degradation. Our results suggest that mitochondria-targeted therapeutic strategies may hold promise for decreasing arterial stiffening with aging in humans, possibly decreasing the risk of many chronic age-related clinical disorders. PMID:29074712

Cell wall formation in zoospores of Allomyces arbuscula. II. Development of surface structure of encysted haploid zoospores, rhizoids, and hyphae.

PubMed

Kroh, M; Hendriks, H; Kirby, E G; Sassen, M M

1976-08-01

Development of haploid meiospores of Allomyces arbuscula into germling cells with rhizoids and hyphae was followed during incubation in complete growth medium. The surface structure of encysted meiospores, rhizoids and hyphae before and after extraction of amorphous materials with ethanolic KOH was studied by means of carbon-platinum replicas. After 2--3 min incubation in complete medium 10% of the meiospores were surrounded by a cell wall containing microfibrils embedded in a matrix. Structure of cell walls of encysted meiospores, rhizoids, and hyphae differ from one another by the location of amorphous materials and by the arrangement of chitin microfibrils.

Biaxial deformation of collagen and elastin fibers in coronary adventitia

PubMed Central

Chen, Huan; Slipchenko, Mikhail N.; Liu, Yi; Zhao, Xuefeng; Cheng, Ji-Xin; Lanir, Yoram

2013-01-01

The microstructural deformation-mechanical loading relation of the blood vessel wall is essential for understanding the overall mechanical behavior of vascular tissue in health and disease. We employed simultaneous mechanical loading-imaging to quantify in situ deformation of individual collagen and elastin fibers on unstained fresh porcine coronary adventitia under a combination of vessel inflation and axial extension loading. Specifically, the specimens were imaged under biaxial loads to study microscopic deformation-loading behavior of fibers in conjunction with morphometric measurements at the zero-stress state. Collagen fibers largely orientate in the longitudinal direction, while elastin fibers have major orientation parallel to collagen, but with additional orientation angles in each sublayer of the adventitia. With an increase of biaxial load, collagen fibers were uniformly stretched to the loading direction, while elastin fibers gradually formed a network in sublayers, which strongly depended on the initial arrangement. The waviness of collagen decreased more rapidly at a circumferential stretch ratio of λθ = 1.0 than at λθ = 1.5, while most collagen became straightened at λθ = 1.8. These microscopic deformations imply that the longitudinally stiffer adventitia is a direct result of initial fiber alignment, and the overall mechanical behavior of the tissue is highly dependent on the corresponding microscopic deformation of fibers. The microstructural deformation-loading relation will serve as a foundation for micromechanical models of the vessel wall. PMID:24092692

Elastin-like polypeptides: the power of design for smart cell encapsulation.

PubMed

Bandiera, Antonella

2017-01-01

Cell encapsulation technology is still a challenging issue. Innovative methodologies such as additive manufacturing, and alternative bioprocesses, such as cell therapeutic delivery, where cell encapsulation is a key tool are rapidly gaining importance for their potential in regenerative medicine. Responsive materials such as elastin-based recombinant expression products have features that are particularly attractive for cell encapsulation. They can be designed and tailored to meet desired requirements. Thus, they represent promising candidates for the development of new concept-based materials that can be employed in this field. Areas covered: An overview of the design and employment of elastin-like polypeptides for cell encapsulation is given to outline the state of the art. Special attention is paid to the design of the macromolecule employed as well as to the method of matrix formation and the biological system involved. Expert opinion: As a result of recent progress in regenerative medicine there is a compelling need for materials that provide specific properties and demonstrate defined functional features. Rationally designed materials that may adapt according to applied external stimuli and that are responsive to biological systems, such as elastin-like polypeptides, belong to this class of smart material. A run through the components described to date represents a good starting point for further advancement in this area. Employment of these components in cell encapsulation application will promote its advance toward 'smart cell encapsulation technology'.

Intracranial arteries in individuals with the elastin gene hemideletion of Williams syndrome.

PubMed

Wint, D P; Butman, J A; Masdeu, J C; Meyer-Lindenberg, A; Mervis, C B; Sarpal, D; Morris, C A; Berman, K F

2014-01-01

Williams syndrome, a rare genetic disorder with a striking neurobehavioral profile characterized by extreme sociability and impaired visuospatial construction abilities, is caused by a hemideletion that includes the elastin gene, resulting in frequent supravavular aortic stenosis and other stenotic arterial lesions. Strokes have been reported in Williams syndrome. Although the extracranial carotid artery has been studied in a sample of patients with Williams syndrome, proximal intracranial arteries have not. Using MRA, we studied the intracranial vessels in 27 participants: 14 patients with Williams syndrome (age range, 18-44 years; mean age, 27.3 ± 9.1; 43% women) and 13 healthy control participants with similar age and sex distribution (age range, 22-52 years; mean age, 33.4 ± 7.6; 46% women). All participants with Williams syndrome had hemideletions of the elastin gene. Blinded to group allocation or to any other clinical data, a neuroradiologist determined the presence of intracranial vascular changes in the 2 groups. The Williams syndrome group and the healthy control group had similar patency of the proximal intracranial arteries, including the internal carotid and vertebral arteries; basilar artery; and stem and proximal branches of the anterior cerebral artery, MCA, and posterior cerebral arteries. The postcommunicating segment of the anterior cerebral artery was longer in the Williams syndrome group. Despite the elastin haploinsufficiency, the proximal intracranial arteries in Williams syndrome preserve normal patency.

Histopathological Differences Between the Anterior and Posterior Brain Arteries as a Function of Aging.

PubMed

Roth, William; Morgello, Susan; Goldman, James; Mohr, Jay P; Elkind, Mitchell S V; Marshall, Randolph S; Gutierrez, Jose

2017-03-01

We tested the hypothesis that posterior brain arteries differ pathologically from anterior brain arteries and that this difference varies with age. Brain large arteries from 194 autopsied individuals (mean age 56±17 years, 63% men, 25% nonwhite, 17% with brain infarcts) were analyzed to obtain the areas of arterial layers and lumen as well as the relative content of elastin, collagen, and amyloid. Visual rating was used to determine the prevalence of atheroma, calcification, vasa vasorum , pattern of intima thickening, and internal elastic lamina gaps. We used multilevel models adjusting for age, sex, ethnicity, vascular risk factors, artery type and location, and multiple comparisons. Of 1362 large artery segments, 5% had vasa vasorum, 5% had calcifications, 15% had concentric intimal thickening, and 11% had atheromas. Posterior brain arteries had thinner walls, less elastin, and more concentric intima thickening than anterior brain arteries. Compared to anterior brain arteries, the basilar artery had higher arterial area encircled by the internal elastic lamina, whereas the vertebral arteries had higher prevalence of elastin loss, concentric intima thickening, and nonatherosclerotic stenosis. In younger individuals, vertebral artery calcifications were more likely than calcification in anterior brain arteries, but this difference attenuated with age. Posterior brain arteries differ pathologically from anterior brain arteries in the degree of wall thickening, elastin loss, and concentric intimal thickening. © 2017 American Heart Association, Inc.

Elastin Cables Define the Axial Connective Tissue System in the Murine Lung.

PubMed

Wagner, Willi; Bennett, Robert D; Ackermann, Maximilian; Ysasi, Alexandra B; Belle, Janeil; Valenzuela, Cristian D; Pabst, Andreas; Tsuda, Akira; Konerding, Moritz A; Mentzer, Steven J

2015-11-01

The axial connective tissue system is a fiber continuum of the lung that maintains alveolar surface area during changes in lung volume. Although the molecular anatomy of the axial system remains undefined, the fiber continuum of the lung is central to contemporary models of lung micromechanics and alveolar regeneration. To provide a detailed molecular structure of the axial connective tissue system, we examined the extracellular matrix of murine lungs. The lungs were decellularized using a 24 hr detergent treatment protocol. Systematic evaluation of the decellularized lungs demonstrated no residual cellular debris; morphometry demonstrated a mean 39 ± 7% reduction in lung dimensions. Scanning electron microscopy (SEM) demonstrated an intact structural hierarchy within the decellularized lung. Light, fluorescence, and SEM of precision-cut lung slices demonstrated that alveolar duct structure was defined by a cable line element encased in basement membrane. The cable line element arose in the distal airways, passed through septal tips and inserted into neighboring blood vessels and visceral pleura. The ropelike appearance, collagenase resistance and anti-elastin immunostaining indicated that the cable was an elastin macromolecule. Our results indicate that the helical line element of the axial connective tissue system is composed of an elastin cable that not only defines the structure of the alveolar duct, but also integrates the axial connective tissue system into visceral pleura and peripheral blood vessels. © 2015 Wiley Periodicals, Inc.

Advances in biomimetic regeneration of elastic matrix structures

PubMed Central

Sivaraman, Balakrishnan; Bashur, Chris A.

2012-01-01

Elastin is a vital component of the extracellular matrix, providing soft connective tissues with the property of elastic recoil following deformation and regulating the cellular response via biomechanical transduction to maintain tissue homeostasis. The limited ability of most adult cells to synthesize elastin precursors and assemble them into mature crosslinked structures has hindered the development of functional tissue-engineered constructs that exhibit the structure and biomechanics of normal native elastic tissues in the body. In diseased tissues, the chronic overexpression of proteolytic enzymes can cause significant matrix degradation, to further limit the accumulation and quality (e.g., fiber formation) of newly deposited elastic matrix. This review provides an overview of the role and importance of elastin and elastic matrix in soft tissues, the challenges to elastic matrix generation in vitro and to regenerative elastic matrix repair in vivo, current biomolecular strategies to enhance elastin deposition and matrix assembly, and the need to concurrently inhibit proteolytic matrix disruption for improving the quantity and quality of elastogenesis. The review further presents biomaterial-based options using scaffolds and nanocarriers for spatio-temporal control over the presentation and release of these biomolecules, to enable biomimetic assembly of clinically relevant native elastic matrix-like superstructures. Finally, this review provides an overview of recent advances and prospects for the application of these strategies to regenerating tissue-type specific elastic matrix structures and superstructures. PMID:23355960

Comparative structural and computational analysis supports eighteen cellulose synthases in the plant cellulose synthesis complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nixon, B. Tracy; Mansouri, Katayoun; Singh, Abhishek

A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individualmore » lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In conclusion, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains.« less

On the molecular origins of biomass recalcitrance: the interaction network and solvation structures of cellulose microfibrils.

PubMed

Gross, Adam S; Chu, Jhih-Wei

2010-10-28

Biomass recalcitrance is a fundamental bottleneck to producing fuels from renewable sources. To understand its molecular origin, we characterize the interaction network and solvation structures of cellulose microfibrils via all-atom molecular dynamics simulations. The network is divided into three components: intrachain, interchain, and intersheet interactions. Analysis of their spatial dependence and interaction energetics indicate that intersheet interactions are the most robust and strongest component and do not display a noticeable dependence on solvent exposure. Conversely, the strength of surface-exposed intrachain and interchain hydrogen bonds is significantly reduced. Comparing the interaction networks of I(β) and I(α) cellulose also shows that the number of intersheet interactions is a clear descriptor that distinguishes the two allomorphs and is consistent with the observation that I(β) is the more stable form. These results highlight the dominant role of the often-overlooked intersheet interactions in giving rise to biomass recalcitrance. We also analyze the solvation structures around the surfaces of microfibrils and show that the structural and chemical features at cellulose surfaces constrict water molecules into specific density profiles and pair correlation functions. Calculations of water density and compressibility in the hydration shell show noticeable but not drastic differences. Therefore, specific solvation structures are more prominent signatures of different surfaces.

Solid-state NMR investigations of cellulose structure and interactions with matrix polysaccharides in plant primary cell walls.

PubMed

Wang, Tuo; Hong, Mei

2016-01-01

Until recently, the 3D architecture of plant cell walls was poorly understood due to the lack of high-resolution techniques for characterizing the molecular structure, dynamics, and intermolecular interactions of the wall polysaccharides in these insoluble biomolecular mixtures. We introduced multidimensional solid-state NMR (SSNMR) spectroscopy, coupled with (13)C labelling of whole plants, to determine the spatial arrangements of macromolecules in near-native plant cell walls. Here we review key evidence from 2D and 3D correlation NMR spectra that show relatively few cellulose-hemicellulose cross peaks but many cellulose-pectin cross peaks, indicating that cellulose microfibrils are not extensively coated by hemicellulose and all three major polysaccharides exist in a single network rather than two separate networks as previously proposed. The number of glucan chains in the primary-wall cellulose microfibrils has been under active debate recently. We show detailed analysis of quantitative (13)C SSNMR spectra of cellulose in various wild-type (WT) and mutant Arabidopsis and Brachypodium primary cell walls, which consistently indicate that primary-wall cellulose microfibrils contain at least 24 glucan chains. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Differential regulation of cellulose orientation at the inner and outer face of epidermal cells in the Arabidopsis hypocotyl.

PubMed

Crowell, Elizabeth Faris; Timpano, Hélène; Desprez, Thierry; Franssen-Verheijen, Tiny; Emons, Anne-Mie; Höfte, Herman; Vernhettes, Samantha

2011-07-01

It is generally believed that cell elongation is regulated by cortical microtubules, which guide the movement of cellulose synthase complexes as they secrete cellulose microfibrils into the periplasmic space. Transversely oriented microtubules are predicted to direct the deposition of a parallel array of microfibrils, thus generating a mechanically anisotropic cell wall that will favor elongation and prevent radial swelling. Thus far, support for this model has been most convincingly demonstrated in filamentous algae. We found that in etiolated Arabidopsis thaliana hypocotyls, microtubules and cellulose synthase trajectories are transversely oriented on the outer surface of the epidermis for only a short period during growth and that anisotropic growth continues after this transverse organization is lost. Our data support previous findings that the outer epidermal wall is polylamellate in structure, with little or no anisotropy. By contrast, we observed perfectly transverse microtubules and microfibrils at the inner face of the epidermis during all stages of cell expansion. Experimental perturbation of cortical microtubule organization preferentially at the inner face led to increased radial swelling. Our study highlights the previously underestimated complexity of cortical microtubule organization in the shoot epidermis and underscores a role for the inner tissues in the regulation of growth anisotropy.

Comparative structural and computational analysis supports eighteen cellulose synthases in the plant cellulose synthesis complex

DOE PAGES

Nixon, B. Tracy; Mansouri, Katayoun; Singh, Abhishek; ...

2016-06-27

A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individualmore » lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In conclusion, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains.« less

Differential Regulation of Cellulose Orientation at the Inner and Outer Face of Epidermal Cells in the Arabidopsis Hypocotyl[W

PubMed Central

Crowell, Elizabeth Faris; Timpano, Hélène; Desprez, Thierry; Franssen-Verheijen, Tiny; Emons, Anne-Mie; Höfte, Herman; Vernhettes, Samantha

2011-01-01

It is generally believed that cell elongation is regulated by cortical microtubules, which guide the movement of cellulose synthase complexes as they secrete cellulose microfibrils into the periplasmic space. Transversely oriented microtubules are predicted to direct the deposition of a parallel array of microfibrils, thus generating a mechanically anisotropic cell wall that will favor elongation and prevent radial swelling. Thus far, support for this model has been most convincingly demonstrated in filamentous algae. We found that in etiolated Arabidopsis thaliana hypocotyls, microtubules and cellulose synthase trajectories are transversely oriented on the outer surface of the epidermis for only a short period during growth and that anisotropic growth continues after this transverse organization is lost. Our data support previous findings that the outer epidermal wall is polylamellate in structure, with little or no anisotropy. By contrast, we observed perfectly transverse microtubules and microfibrils at the inner face of the epidermis during all stages of cell expansion. Experimental perturbation of cortical microtubule organization preferentially at the inner face led to increased radial swelling. Our study highlights the previously underestimated complexity of cortical microtubule organization in the shoot epidermis and underscores a role for the inner tissues in the regulation of growth anisotropy. PMID:21742992

Fluorescent cellulose microfibrils as substrate for the detection of cellulase activity.

PubMed

Helbert, William; Chanzy, Henri; Husum, Tommy Lykke; Schülein, Martin; Ernst, Steffen

2003-01-01

To devise a sensitive cellulase assay based on substrates having most of the physical characteristics of native cellulose, 5-(4,6-dichlorotriazinyl)aminofluorescein (DTAF) was used as a grafting agent to prepare suspensions of fluorescent microfibrils from bacterial cellulose. These suspensions were digested by a series of commercially relevant cellulases from Humicola insolens origin: cloned Cel6B and Cel 45A as well as crude H. insolens complex. The digestion induced the release of fluorescent cellodextrins as well as reducing sugars. After adequate centrifugation, these soluble products were analyzed as a function of grafting content, digestion time, and cellulase characteristics. The resulting data allowed the grafting conditions to be optimized in order to maximize the quantity of soluble products and therefore to increase the sensitivity of the detection. A comparison between the amount of released fluorescence and that of released reducing sugar allowed the differentiation between processive exo and endo cellulase activities. The casting of films of DTAF-grafted microfibrils at the bottom of the microwell titer plates also led to sensitive cellulase detection. As these films kept their integrity and remained firmly glued to the well bottom during the digestion time, they are tailored made for a full automation of the cellulases testing.

Comparative Structural and Computational Analysis Supports Eighteen Cellulose Synthases in the Plant Cellulose Synthesis Complex

PubMed Central

Nixon, B. Tracy; Mansouri, Katayoun; Singh, Abhishek; Du, Juan; Davis, Jonathan K.; Lee, Jung-Goo; Slabaugh, Erin; Vandavasi, Venu Gopal; O’Neill, Hugh; Roberts, Eric M.; Roberts, Alison W.; Yingling, Yaroslava G.; Haigler, Candace H.

2016-01-01

A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individual lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In summary, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains. PMID:27345599

Characterization of the viscoelastic behavior of a simplified collagen micro-fibril based on molecular dynamics simulations.

PubMed

Ghodsi, Hossein; Darvish, Kurosh

2016-10-01

Collagen fibril is a major component of connective tissues such as bone, tendon, blood vessels, and skin. The mechanical properties of this highly hierarchical structure are greatly influenced by the presence of covalent cross-links between individual collagen molecules. This study investigates the viscoelastic behavior of a collagen lysine-lysine cross-link based on creep simulations with applied forces in the range or 10 to 2000pN using steered molecular dynamics (SMD). The viscoelastic model of the cross-link was combined with a system composed by two segments of adjacent collagen molecules hence representing a reduced viscoelastic model for a simplified micro-fibril. It was found that the collagen micro-fibril assembly had a steady-state Young׳s modulus ranging from 2.24 to 3.27GPa, which is in agreement with reported experimental measurements. The propagation of longitudinal force wave along the molecule was implemented by adding a delay element to the model. The force wave speed was found to be correlated with the speed of one-dimensional elastic waves in rods. The presented reduced model with three degrees of freedom can serve as a building block for developing models of the next level of hierarchy, i.e., a collagen fibril. Copyright © 2016 Elsevier Ltd. All rights reserved.

Elastin receptor (S-gal) occupancy by elastin peptides modulates T-cell response during murine emphysema.

PubMed

Meghraoui-Kheddar, Aïda; Pierre, Alexandre; Sellami, Mehdi; Audonnet, Sandra; Lemaire, Flora; Le Naour, Richard

2017-09-01

Chronic obstructive pulmonary disease and emphysema are associated with increased elastin peptides (EP) production because of excessive breakdown of lung connective tissue. We recently reported that exposure of mice to EP elicited hallmark features of emphysema. EP effects are largely mediated through a receptor complex that includes the elastin-binding protein spliced-galactosidase (S-gal). In previous studies, we established a correlation between cytokine production and S-gal protein expression in EP-treated immune cells. In this study, we investigated the S-gal-dependent EP effects on T-helper (Th) and T-cytotoxic (Tc) responses during murine EP-triggered pulmonary inflammation. C57BL/6J mice were endotracheally instilled with the valine-glycine-valine-alanine-proline-glycine (VGVAPG) elastin peptide, and, 21 days after treatment, local and systemic T-lymphocyte phenotypes were analyzed at cytokine and transcription factor expression levels by multicolor flow cytometry. Exposure of mice to the VGVAPG peptide resulted in a significant increase in the proportion of the CD4 + and CD8 + T cells expressing the cytokines IFN-γ or IL-17a and the transcription factors T-box expressed in T cells or retinoic acid-related orphan receptor-γt (RORγt) without effects on IL-4 and Gata-binding protein 3 to DNA sequence [A/T]GATA[A/G] expression. These effects were maximized when each T-cell subpopulation was challenged ex vivo with EP, and they were inhibited in vivo when an analogous peptide antagonizing the EP/S-gal interactions was instilled together with the VGVAPG peptide. This study demonstrates that, during murine emphysema, EP-S-gal interactions contribute to a Th-1 and Th-17 proinflammatory T-cell response combined with a Tc-1 response. Our study also highlights the S-gal receptor as a putative pharmacological target to modulate such an immune response. Copyright © 2017 the American Physiological Society.

MicroRNA-181b Controls Atherosclerosis and Aneurysms Through Regulation of TIMP-3 and Elastin

PubMed Central

Di Gregoli, Karina; Mohamad Anuar, Nur Najmi; Bianco, Rosaria; White, Stephen J.; Newby, Andrew C.; George, Sarah J.

2017-01-01

Rationale: Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood. Objective: To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms. Methods and Results: Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe−/− and Ldlr−/−, we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II–infused Apoe−/− and Ldlr−/− mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3−/− mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis. Conclusions: Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture. PMID:27756793

Role of Matrix Metalloproteinases-1 and -2 in Interleukin-13–Suppressed Elastin in Airway Fibroblasts in Asthma

PubMed Central

Slade, David; Church, Tony D.; Francisco, Dave; Heck, Karissa; Sigmon, R. Wesley; Ghio, Michael; Murillo, Anays; Firszt, Rafael; Lugogo, Njira L.; Que, Loretta; Sunday, Mary E.; Kraft, Monica

2016-01-01

Elastin synthesis and degradation in the airway and lung parenchyma contribute to airway mechanics, including airway patency and elastic recoil. IL-13 mediates many features of asthma pathobiology, including airway remodeling, but the effects of IL-13 on elastin architecture in the airway wall are not known. We hypothesized that IL-13 modulates elastin expression in airway fibroblasts from subjects with allergic asthma. Twenty-five subjects with mild asthma (FEV1, 89 ± 3% predicted) and 30 normal control subjects (FEV1, 102 ± 2% predicted) underwent bronchoscopy with endobronchial biopsy. Elastic fibers were visualized in airway biopsy specimens using Weigert’s resorcin-fuchsin elastic stain. Airway fibroblasts were exposed to IL-13; a pan-matrix metalloproteinase (MMP) inhibitor (GM6001); specific inhibitors to MMP-1, -2, -3, and -8; and combinations of IL-13 with MMP inhibitors in separate conditions in serum-free media for 48 hours. Elastin (ELN) expression as well as MMP secretion and activity were quantified. Results of this study show that elastic fiber staining of airway biopsy tissue was significantly associated with methacholine PC20 (i.e., the provocative concentration of methacholine resulting in a 20% fall in FEV1 levels) in patients with asthma. IL-13 significantly suppressed ELN expression in asthmatic airway fibroblasts as compared with normal control fibroblasts. The effect of IL-13 on ELN expression was significantly correlated with postbronchodilator FEV1/FVC in patients with asthma. MMP inhibition significantly stimulated ELN expression in patients with asthma as compared with normal control subjects. Specific inhibition of MMP-1 and MMP-2, but not MMP-3 or MMP-8, reversed the IL-13–induced suppression of ELN expression. In asthma, MMP-1 and MMP-2 mediate IL-13–induced suppression of ELN expression in airway fibroblasts. PMID:26074138

MicroRNA-181b Controls Atherosclerosis and Aneurysms Through Regulation of TIMP-3 and Elastin.

PubMed

Di Gregoli, Karina; Mohamad Anuar, Nur Najmi; Bianco, Rosaria; White, Stephen J; Newby, Andrew C; George, Sarah J; Johnson, Jason L

2017-01-06

Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood. To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms. Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe - /- and Ldlr -/- , we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II-infused Apoe -/- and Ldlr -/- mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3 -/- mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis. Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture. © 2016 The Authors.

13C, 2H NMR Studies of Structural and Dynamical Modifications of Glucose-Exposed Porcine Aortic Elastin

PubMed Central

Silverstein, Moshe C.; Bilici, Kübra; Morgan, Steven W.; Wang, Yunjie; Zhang, Yanhang; Boutis, Gregory S.

2015-01-01

Elastin, the principal component of the elastic fiber of the extracellular matrix, imparts to vertebrate tissues remarkable resilience and longevity. This work focuses on elucidating dynamical and structural modifications of porcine aortic elastin exposed to glucose by solid-state NMR spectroscopic and relaxation methodologies. Results from macroscopic stress-strain tests are also presented and indicate that glucose-treated elastin is mechanically stiffer than the same tissue without glucose treatment. These measurements show a large hysteresis in the stress-strain behavior of glucose-treated elastin—a well-known signature of viscoelasticity. Two-dimensional relaxation NMR methods were used to investigate the correlation time, distribution, and population of water in these samples. Differences are observed between the relative populations of water, whereas the measured correlation times of tumbling motion of water across the samples were similar. 13C magic-angle-spinning NMR methods were applied to investigate structural and dynamical modifications after glucose treatment. Although some overall structure is preserved, the process of glucose exposure results in more heterogeneous structures and slower mobility. The correlation times of tumbling motion of the 13C-1H internuclear vectors in the glucose-treated sample are larger than in untreated samples, pointing to their more rigid structure. The 13C cross-polarization spectra reveal a notably increased α-helical character in the alanine motifs after glucose exposure. Results from molecular dynamics simulations are provided that add further insight into dynamical and structural changes of a short repeat, [VPGVG]5, an alanine pentamer, desmosine, and isodesmosine sites with and without glucose. The simulations point to changes in the entropic and energetic contributions in the retractive forces of VPGVG and AAAAA motifs. The most notable change is the increase of the energetic contribution in the retractive force due to peptide-glucose interactions of the VPGVG motif, which may play an important role in the observed stiffening in glucose-treated elastin. PMID:25863067

Role of Matrix Metalloproteinases-1 and -2 in Interleukin-13-Suppressed Elastin in Airway Fibroblasts in Asthma.

PubMed

Ingram, Jennifer L; Slade, David; Church, Tony D; Francisco, Dave; Heck, Karissa; Sigmon, R Wesley; Ghio, Michael; Murillo, Anays; Firszt, Rafael; Lugogo, Njira L; Que, Loretta; Sunday, Mary E; Kraft, Monica

2016-01-01

Elastin synthesis and degradation in the airway and lung parenchyma contribute to airway mechanics, including airway patency and elastic recoil. IL-13 mediates many features of asthma pathobiology, including airway remodeling, but the effects of IL-13 on elastin architecture in the airway wall are not known. We hypothesized that IL-13 modulates elastin expression in airway fibroblasts from subjects with allergic asthma. Twenty-five subjects with mild asthma (FEV1, 89 ± 3% predicted) and 30 normal control subjects (FEV1, 102 ± 2% predicted) underwent bronchoscopy with endobronchial biopsy. Elastic fibers were visualized in airway biopsy specimens using Weigert's resorcin-fuchsin elastic stain. Airway fibroblasts were exposed to IL-13; a pan-matrix metalloproteinase (MMP) inhibitor (GM6001); specific inhibitors to MMP-1, -2, -3, and -8; and combinations of IL-13 with MMP inhibitors in separate conditions in serum-free media for 48 hours. Elastin (ELN) expression as well as MMP secretion and activity were quantified. Results of this study show that elastic fiber staining of airway biopsy tissue was significantly associated with methacholine PC20 (i.e., the provocative concentration of methacholine resulting in a 20% fall in FEV1 levels) in patients with asthma. IL-13 significantly suppressed ELN expression in asthmatic airway fibroblasts as compared with normal control fibroblasts. The effect of IL-13 on ELN expression was significantly correlated with postbronchodilator FEV1/FVC in patients with asthma. MMP inhibition significantly stimulated ELN expression in patients with asthma as compared with normal control subjects. Specific inhibition of MMP-1 and MMP-2, but not MMP-3 or MMP-8, reversed the IL-13-induced suppression of ELN expression. In asthma, MMP-1 and MMP-2 mediate IL-13-induced suppression of ELN expression in airway fibroblasts.

Antibodies to elastin peptides in sera of Belgian Draught horses with chronic progressive lymphoedema.

PubMed

van Brantegem, L; de Cock, H E V; Affolter, V K; Duchateau, L; Hoogewijs, M K; Govaere, J; Ferraro, G L; Ducatelle, R

2007-09-01

Chronic progressive lymphoedema (CPL) is a recently recognised disease of the lymphatic system characterised by lesions in the skin of the lower legs in several draught horse breeds, including the Belgian Draught hourse. Clinical signs slowly progress and result in severe disfigurement of the limbs. Ideally, supportive treatment should be started early in the disease process. However early diagnosis and monitoring progression of CPL is still a challenge. Elastin changes, characterised by morphological alterations as well as increased desmosine levels, in the skin of the distal limbs of horses affected with CPL are probably associated with a marked release of elastin degradation products, which elicit production of circulating anti-elastin antibodies (AEAbs) in the serum. An enzyme-linked immunosorbent assay (ELISA) for detection of serum AEAbs may document elastin breakdown. An ELISA technique was used to evaluate levels of AEAbs in sera of 97 affected Belgian Draught horses that were clinically healthy except for possible skin lesions, associated with CPL in their distal limbs. The horses were divided into 5 groups according to the severity of these skin lesions: normal horses (Group 1, n = 36), horses with mild lesions (Group 2, n = 43), horses with moderate lesions (Group 3, n = 8), horses with severe lesions (Group 4, n = 10) and, as a control, healthy Warmblood horses, unaffected by the disease (Group 5, n = 83). Horses with clinical signs of CPL had significantly higher AEAb levels compared to clinically normal Belgian Draught horses and to healthy Warmblood horses. These levels correlated with severity of lesions. CPL in draught horses is associated with an increase of serum AEAbs. Evaluation of serum levels of AEAbs by ELISA might be a useful diagnostic aid for CPL. Pathological degradation of elastic fibres, resulting in deficient support of the distal lymphatics, is proposed as a contributing factor for CPL in Belgian Draught horses.

Elastomeric Polypeptides

PubMed Central

van Eldijk, Mark B.; McGann, Christopher L.

2013-01-01

Elastomeric polypeptides are very interesting biopolymers and are characterized by rubber-like elasticity, large extensibility before rupture, reversible deformation without loss of energy, and high resilience upon stretching. Their useful properties have motivated their use in a wide variety of materials and biological applications. This chapter focuses on elastin and resilin – two elastomeric biopolymers – and the recombinant polypeptides derived from them (elastin-like polypeptides and resilin-like polypeptides). This chapter also discusses the applications of these recombinant polypeptides in the fields of purification, drug delivery, and tissue engineering. PMID:21826606

Influence of surface modified cellulose microfibrils on the improved mechanical properties of poly (lactic acid).

PubMed

Johari, Atul P; Kurmvanshi, S K; Mohanty, S; Nayak, S K

2016-03-01

Cellulose microfibrils (CMF) were extracted from sisal fiber and characterized. Biocomposites of PLA reinforced with CMF were fabricated employing melt blending technique followed by injection moulding. The biocomposites were subjected to various characterization studies to investigate the effect of CMF within the PLA matrix. Differential scanning calorimetry (DSC) measurements confirmed that the addition of CMF accelerates the crystallization process of PLA matrix. Addition of 5 wt.% of CMF with and without compatibilizers and plasticizers such as maleic anhydride, polyethylene glycol and acetyltributyl citrate in PLA improved the crystallization of PLA up to 100 °C. MA grafting gave moderate effects on both the stiffness and ductility, exhibiting optimum properties. Copyright © 2015 Elsevier B.V. All rights reserved.

[Purification and physicochemical properties of Bacillus thuringiensis IMB B-7324 peptidase with elastolytic and fibrinolytic activity].

PubMed

Matseliukh, O V; Nidialkova, N A; Varbanets', L D

2012-01-01

The scheme of isolation and purification of Bacillus thuringiensis IMV B-7324 peptidase has been developed. This scheme includes ammonium sulfate precipitation and chromatography on neutral and charged TSK-gels. It was found that the enzyme hydrolyzes elastin and fibrin. The molecular weight is 26 kDa. It was shown that the enzyme is an alkaline serine peptidase. The optimal pH of hydrolysis of elastin and fibrin were 9.0 and 10.0, respectively. The optimal temperature of elastin and fibrin hydrolysis are 40 and 50 degrees C, respectively. The high stability of the purified preparation in the studied range of pH and temperature was shown. The stabilizing effect of zinc at a concentration of 1 mM on the elastase activity, and the inhibitory effect of other divalent cations under study have been established. The investigated chloride and acetate anions reduced activity by 20%, while phosphate anions increased activity by 15-30%.

Multiphoton microscopy of ECM proteins in baboon aortic leaflet

NASA Astrophysics Data System (ADS)

Gonzalez, Mariacarla; Saytashev, Ilyas; Luna, Camila; Gonzalez, Brittany; Pinero, Alejandro; Perez, Manuel; Ramaswamy, Sharan; Ramella-Roman, Jessica

2018-02-01

The extracellular matrix (ECM) plays crucial role in defining mechanical properties of a heart valve yet the mechanobiological role of the ECM proteins - collagen and elastin - in living heart valve leaflets is still poorly understood. In this study, non-linear microscopy was used to obtain three dimensional images of collagen and elastin arrangement in aortic leaflets under combined steady flow (850 ml/min) and cyclic flexure (1 Hz) mechanical (dynamic) training. A novel bioreactor capable of mimicking the flow conditions in a living heart was used in this study and was optimized for microscopic imagery. A custom made non-linear microscope was used in this study to provide Second Harmonic Generation (SHG) imaging of collagen arrangement and two-photon imaging of elastin. Two control and three trained leaflet samples from static and dynamic tissue culture were imaged to observe protein changes in the tissue for a period of seven days. Dynamic training led to a decrease in alignment index of the protein fibers compared to the static treatment.

Dual stimuli-sensitive dendrimers: Photothermogenic gold nanoparticle-loaded thermo-responsive elastin-mimetic dendrimers.

PubMed

Fukushima, Daichi; Sk, Ugir Hossain; Sakamoto, Yasuhiro; Nakase, Ikuhiko; Kojima, Chie

2015-08-01

Dendrimers are synthetic macromolecules with unique structures that can work as nanoplatforms for both photothermogenic gold nanoparticles (AuNPs) and thermosensitive elastin-like peptides (ELPs) with valine-proline-glycine-valine-glycine (VPGVG) repeats. In this study, photothermogenic AuNPs were loaded into thermo-responsive elastin-mimetic dendrimers (dendrimers conjugating ELPs at their periphery) to produce dual stimuli-sensitive nanoparticles. Polyamidoamine G4 dendrimers were modified with acetylated VPGVG and (VPGVG)2, and the resulting materials were named ELP1-den and ELP2-den, respectively. The AuNPs were prepared by the reduction of Au ions using a dendrimer-nanotemplated method. The AuNP-loaded elastin-mimetic dendrimers exhibited photothermal properties. ELP1-den and ELP2-den showed similar temperature-dependent changes in their conformations. Phase transitions were observed at around 55°C and 35°C for the AuNP-loaded ELP1-den and AuNP-loaded ELP2-den, respectively, but not for the corresponding PEGylated dendrimer. In contrast to the AuNP-loaded PEGylated dendrimer, AuNP-loaded ELP2-den readily associated with cells and induced efficient photocytotoxicity at 37°C. The cell association and the photocytotoxicity properties of AuNP-loaded ELP2-den could be controlled by temperature. These results therefore suggest that dual stimuli-sensitive dendrimer nanoparticles of this type could be used for photothermal therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

Continuous exposure to low amplitude extremely low frequency electrical fields characterizing the vascular streaming potential alters elastin accumulation in vascular smooth muscle cells.

PubMed

Bergethon, Peter R; Kindler, Dean D; Hallock, Kevin; Blease, Susan; Toselli, Paul

2013-07-01

In normal development and pathology, the vascular system depends on complex interactions between cellular elements, biochemical molecules, and physical forces. The electrokinetic vascular streaming potential (EVSP) is an endogenous extremely low frequency (ELF) electrical field resulting from blood flowing past the vessel wall. While generally unrecognized, it is a ubiquitous electrical biophysical force to which the vascular tree is exposed. Extracellular matrix elastin plays a central role in normal blood vessel function and in the development of atherosclerosis. It was hypothesized that ELF fields of low amplitude would alter elastin accumulation, supporting a link between the EVSP and the biology of vascular smooth muscle cells. Neonatal rat aortic smooth muscle cell cultures were exposed chronically to electrical fields characteristic of the EVSP. Extracellular protein accumulation, DNA content, and electron microscopic (EM) evaluation were performed after 2 weeks of exposure. Stimulated cultures showed no significant change in cellular proliferation as measured by the DNA concentration. The per-DNA normalized protein in the extracellular matrix was unchanged while extracellular elastin accumulation decreased 38% on average. EM analysis showed that the stimulated cells had a 2.85-fold increase in mitochondrial number. These results support the formulation that ELF fields are a potential factor in both normal vessel biology and in the pathogenesis of atherosclerotic diseases including heart disease, stroke, and peripheral vascular disease. Copyright © 2013 Wiley Periodicals, Inc.

Extracellular Matrix Disarray as A Mechanism for Greater Abdominal vs. Thoracic Aortic Stiffness with Aging in Primates

PubMed Central

Zhang, Jie; Zhao, Xin; Vatner, Dorothy E; McNulty, Tara; Bishop, Sanford; Sun, Zhe; Shen, You-Tang; Chen, Li; Meininger, Gerald A; Vatner, Stephen F

2016-01-01

Objective Increased vascular stiffness is central to the pathophysiology of aging, hypertension, diabetes and atherosclerosis. However, relatively few studies have examined vascular stiffness in both the thoracic and abdominal aorta with aging, despite major differences in anatomy, embryological origin and relation to aortic aneurysm. Approach and Results The two other unique features of this study were 1) to study young (9±1 years) and old (26±1 years) male monkeys, and 2) to study direct and continuous measurements of aortic pressure and thoracic and abdominal aortic diameters in conscious monkeys. As expected, aortic stiffness, β, was increased p<0.05, 2–3 fold, in old vs. young thoracic aorta, and augmented further with superimposition of acute hypertension with phenylephrine. Surprisingly, stiffness was not greater in old thoracic aorta than young abdominal aorta. These results can be explained in part by the collagen/elastin ratio, but more importantly, by disarray of collagen and elastin, which correlated best with vascular stiffness. However, vascular smooth muscle cell stiffness, was not different in thoracic vs. abdominal aorta in either young or old monkeys. Conclusions Thus, aortic stiffness increases with aging as expected, but the most severe increases in aortic stiffness observed in the abdominal aorta is novel, where values in young monkeys equaled, or even exceeded, values of thoracic aortic stiffness in old monkeys. These results can be explained by alterations in collagen/elastin ratio, but even more importantly by collagen and elastin disarray. PMID:26891739

Murray's Law in elastin haploinsufficient (Eln+/-) and wild-type (WT) mice.

PubMed

Sather, Bradley A; Hageman, Daniel; Wagenseil, Jessica E

2012-12-01

Using either the principle of minimum energy or constant shear stress, a relation can be derived that predicts the diameters of branching vessels at a bifurcation. This relation, known as Murray's Law, has been shown to predict vessel diameters in a variety of cardiovascular systems from adult humans to developing chicks. The goal of this study is to investigate Murray's Law in vessels from mice that are haploinsufficient for the elastin protein (Eln+/-). Elastin is one of the major proteins in the blood vessel wall and is organized in concentric rings, known as lamellae, with smooth muscle cells (SMCs) around the vessel lumen. Eln+/- mice have an increased number of lamellae, as well as smaller, thinner vessels. It is possible that due to decreased amounts of elastin available for vessel wall remodeling during development and in adulthood, Eln+/- vessels would not follow Murray's Law. We examined vessel bifurcations in six different physiologic regions, including the brain, heart, epidermis, ceocum (or cecum), testes, and intestines, in Eln+/- mice and wild-type (WT) littermates. All vessels were between 40 and 300 μm in diameter. We found that the diameters of both Eln+/- and WT vessels have an average of 13% error from the diameters predicted by Murray's Law, with no significant differences between genotypes or physiologic regions. The data suggest that vessels are optimized to follow Murray's Law, despite limitations on the proteins available for growth and remodeling of the vessel wall.

Quantitative comparison of structure and dynamics of elastin following three isolation schemes by 13C solid state NMR and MALDI mass spectrometry.

PubMed

Papaioannou, A; Louis, M; Dhital, B; Ho, H P; Chang, E J; Boutis, G S

2015-05-01

Methods for isolating elastin from fat, collagen, and muscle, commonly used in the design of artificial elastin based biomaterials, rely on exposing tissue to harsh pH levels and temperatures that usually denature many proteins. At present, a quantitative measurement of the modifications to elastin following isolation from other extracellular matrix constituents has not been reported. Using magic angle spinning (13)C NMR spectroscopy and relaxation methodologies, we have measured the modification in structure and dynamics following three known purification protocols. Our experimental data reveal that the (13)C spectra of the hydrated samples appear remarkably similar across the various purification methods. Subtle differences in the half maximum widths were observed in the backbone carbonyl suggesting possible structural heterogeneity across the different methods of purification. Additionally, small differences in the relative signal intensities were observed between purified samples. Lyophilizing the samples results in a reduction of backbone motion and reveals additional differences across the purification methods studied. These differences were most notable in the alanine motifs indicating possible changes in cross-linking or structural rigidity. The measured correlation times of glycine and proline moieties are observed to also vary considerably across the different purification methods, which may be related to peptide bond cleavage. Lastly, the relative concentration of desmosine cross-links in the samples quantified by MALDI mass spectrometry is reported. Copyright © 2015 Elsevier B.V. All rights reserved.

Normal number of CGG repeats in the FMR-1 gene and abnormal incorporation of fibrillin into the extracellular matrix in Lujan Syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenhaw, G.A.; Stone, C.; Milewicz, D.

1994-09-01

Lujan syndrome is an X-linked condition that includes mild-to-moderate mental retardation, poor social integration, normal secondary sexual development with normal testicular size, generalized hypotonia, hypernasal voice and dolichostenomelia. Major cardiac complications and lens dislocation have not been reported although severe myopia may occur. All reported cases have had negative cytogenetic screening for fra(X) syndrome but establishing this constellation of findings as a distinctive entity has been difficult. We report 4 males in two sibships with clinical findings consistent with Lujan syndrome, normal karyotypes, negative cytogenetic screening for fra(X) syndrome and a normal number of CGG repeats in the FMR-1 gene.more » Dermal fibroblasts explanted from one of the affected males were used to study fibrillin synthesis secretion and extracellular matrix incorporation into microfibrils. Cells from the affected individual showed normal synthesis and secretion of fibrillin when compared to control cells, but the fibrillin was not incorporated into the extracellular matrix. These results suggest the presence of a gene on the X chromosome which may play a role in microfibril assembly and when deficient may disrupt the incorporation of fibrillin into microfibrils. This may be important not only in normal body morphogenesis but also in the development/function of the brain. More affected individuals are needed to investigate these findings further.« less

Surface functional group dependent apatite formation on bacterial cellulose microfibrils network in a simulated body fluid.

PubMed

Nge, Thi Thi; Sugiyama, Junji

2007-04-01

The apatite forming ability of biopolymer bacterial cellulose (BC) has been investigated by soaking different BC specimens in a simulated body fluid (1.5 SBF) under physiological conditions, at 37 degrees C and pH 7.4, mimicking the natural process of apatite formation. From ATR-FTIR spectra and ICP-AES analysis, the crystalline phase nucleated on the BC microfibrils surface was calcium deficient carbonated apatite through initial formation of octacalcium phosphate (OCP) or OCP like calcium phosphate phase regardless of the substrates. Morphology of the deposits from SEM, FE-SEM, and TEM observations revealed the fine structure of thin film plates uniting together to form apatite globules of various size (from <1 mum to 3 mum) with respect to the substrates. Surface modification by TEMPO (2,2,6,6-tetramethylpyperidine-1-oxyl)-mediated oxidation, which can readily form active carboxyl functional groups upon selective oxidation of primary hydroxyl groups on the surface of BC microfibrils, enhanced the rate of apatite nucleation. Ion exchanged treatment with calcium chloride solution after TEMPO-mediated oxidation was found to be remarkably different from other BC substrates with the highest deposit weight and the smallest apatite globules size. The role of BC substrates to induce mineralization rate differs according to the nature of the BC substrates, which strongly influences the growth behavior of the apatite crystals. (c) 2006 Wiley Periodicals, Inc.

The xyloglucan-cellulose assembly at the atomic scale.

PubMed

Hanus, Jaroslav; Mazeau, Karim

2006-05-01

The assembly of cell wall components, cellulose and xyloglucan (XG), was investigated at the atomistic scale using molecular dynamics simulations. A molecular model of a cellulose crystal corresponding to the allomorph Ibeta and exhibiting a flexible complex external morphology was employed to mimic the cellulose microfibril. The xyloglucan molecules considered were the three typical basic repeat units, differing only in the size of one of the lateral chain. All the investigated XG fragments adsorb nonspecifically onto cellulose fiber; multiple arrangements are equally probable, and every cellulose surface was capable of binding the short XG molecules. The following structural effects emerged: XG molecules that do not have any long side chains tended to adapt themselves nicely to the topology of the microfibril, forming a flat, outstretched conformation with all the sugar residues interacting with the surface. In contrast, the XG molecules, which have long side chains, were not able to adopt a flat conformation that would enable the interaction of all the XG residues with the surface. In addition to revealing the fundamental atomistic details of the XG adsorption on cellulose, the present calculations give a comprehensive understanding of the way the XG molecules can unsorb from cellulose to create a network that forms the cell wall. Our revisited view of the adsorption features of XG on cellulose microfibrils is consistent with experimental data, and a model of the network is proposed. Copyright (c) 2006 Wiley Periodicals, Inc.

Characterization of Cellulose Synthesis in Plant Cells

PubMed Central

Maleki, Samaneh Sadat; Mohammadi, Kourosh; Ji, Kong-shu

2016-01-01

Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4) D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC) from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA) proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family. PMID:27314060

Impact of plant matrix polysaccharides on cellulose produced by surface-tethered cellulose synthases.

PubMed

Basu, Snehasish; Omadjela, Okako; Zimmer, Jochen; Catchmark, Jeffrey M

2017-04-15

Surface immobilized BcsA-B cellulose synthases synthesize crystalline cellulose II under in vitro conditions and were used to explore the interaction between cellulose and hemicelluloses and pectin. The morphology of the cellulose microfibrils changed in the presence of xyloglucan and glucomannan, while pectin did not significantly impact morphology. X-ray diffractometry and FT-IR spectroscopy indicated that crystal size and crystallinity were significantly affected by xyloglucan and glucomannan but not altered by pectin. Glucomannan had the most significant impact on the structure of cellulose and inhibits crystallization. The presence of xyloglucan and glucomannan prevents the proper assembly of cellulose microfibrils and changes the crystalline properties of cellulose II in in vitro conditions, but did not have any impact on cellulose allomorph. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stepwise Mechanism of Temperature-Dependent Coacervation of the Elastin-like Peptide Analogue Dimer, (C(WPGVG)3)2.

PubMed

Tatsubo, Daiki; Suyama, Keitaro; Miyazaki, Masaya; Maeda, Iori; Nose, Takeru

2018-03-13

Elastin-like peptides (ELPs) are distinct, repetitive, hydrophobic sequences, such as (VPGVG) n , that exhibit coacervation, the property of reversible, temperature-dependent self-association and dissociation. ELPs can be found in elastin and have been developed as new scaffold biomaterials. However, the detailed relationship between their amino acid sequences and coacervation properties remains obscure because of the structural flexibility of ELPs. In this study, we synthesized a novel, dimeric ELP analogue (H-C(WPGVG) 3 -NH 2 ) 2 , henceforth abbreviated (CW3)2, and analyzed its self-assembly properties and structural factors as indicators of coacervation. Turbidity measurements showed that (CW3)2 demonstrated coacervation at a concentration much lower than that of its monomeric form and another ELP. In addition, the coacervate held water-soluble dye molecules. Thus, potent and distinct coacervation was obtained with a remarkably short sequence of (CW3)2. Furthermore, fluorescence microscopy, dynamic light scattering, and optical microscopy revealed that the coacervation of (CW3)2 was a stepwise process. The structural factors of (CW3)2 were analyzed by molecular dynamics simulations and circular dichroism spectroscopy. These measurements indicated that helical structures primarily consisting of proline and glycine became more disordered at high temperatures with concurrent, significant exposure of their hydrophobic surfaces. This extreme change in the hydrophobic surface contributes to the potent coacervation observed for (CW3)2. These results provide important insights into more efficient applications of ELPs and their analogues, as well as the coacervation mechanisms of ELP and elastin.

Biomechanical and morphological properties of the multiparous ovine vagina and effect of subsequent pregnancy.

PubMed

Rynkevic, Rita; Martins, Pedro; Hympanova, Lucie; Almeida, Henrique; Fernandes, Antonio A; Deprest, Jan

2017-05-24

Pelvic floor soft tissues undergo changes during the pregnancy. However, the degree and nature of this process is not completely characterized. This study investigates the effect of subsequent pregnancy on biomechanical and structural properties of ovine vagina. Vaginal wall from virgin, pregnant (in their third pregnancy) and parous (one year after third vaginal delivery) Swifter sheep (n=5 each) was harvested. Samples for biomechanics and histology, were cut in longitudinal axis (proximal and distal regions). Outcome measurements describing Young's modulus, ultimate stress and elongation were obtained from stress-strain curves. For histology samples were stained with Miller's Elastica staining. Collagen, elastin and muscle cells and myofibroblasts contents were estimated, using image processing techniques. Statistical analyses were performed in order to determine significant differences among experimental groups. Significant regional differences were identified. The proximal vagina was stiffer than distal, irrespective the reproductive status. During the pregnancy proximal vagina become more compliant than in parous (+47.45%) or virgin sheep (+64.35%). This coincided with lower collagen (-15 to -21%), higher elastin (+30 to +60%), and more smooth muscle cells (+17 to +37%). Vaginal tissue from parous ewes was weaker than of virgins, coinciding with lower collagen (-10%), higher elastin (+50%), more smooth muscle cells (+20%). It could be proposed that after pregnancy biomechanical properties of vagina do not recover to those of virgins. Since elastin has a significant influence on the compliance of soft tissues and collagen is the main "actor" regarding strength, histological analysis performed in this study justifies the mechanical behavior observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chitosan/γ-poly(glutamic acid) scaffolds with surface-modified albumin, elastin and poly-l-lysine for cartilage tissue engineering.

PubMed

Kuo, Yung-Chih; Ku, Hao-Fu; Rajesh, Rajendiran

2017-09-01

Cartilage has limited ability to self-repair due to the absence of blood vessels and nerves. The application of biomaterial scaffolds using biomimetic extracellular matrix (ECM)-related polymers has become an effective approach to production of engineered cartilage. Chitosan/γ-poly(glutamic acid) (γ-PGA) scaffolds with different mass ratios were prepared using genipin as a cross-linker and a freeze-drying method, and their surfaces were modified with elastin, human serum albumin (HSA) and poly-l-lysine (PLL). The scaffolds were formed through a complex between NH 3 + of chitosan and COO - of γ-PGA, confirmed by Fourier transform infrared spectroscopy, and exhibited an interconnected porous morphology in field emission scanning electron microscopy analysis. The prepared chitosan/γ-PGA scaffolds, at a 3:1 ratio, obtained the required porosity (90%), pore size (≥100μm), mechanical strength (compressive strength>4MPa, Young's modulus>4MPa) and biodegradation (30-60%) for articular cartilage tissue engineering applications. Surface modification of the scaffolds showed positive indications with improved activity toward cell proliferation (deoxyribonucleic acid), cell adhesion and ECM (glycoaminoglycans and type II collagen) secretion of bovine knee chondrocytes compared with unmodified scaffolds. In caspase-3 detection, elastin had a higher inhibitory effect on chondrocyte apoptosis in vitro, followed by HSA, and then PLL. We concluded that utilizing chitosan/γ-PGA scaffolds with surface active biomolecules, including elastin, HSA and PLL, can effectively promote the growth of chondrocytes, secrete ECM and improve the regenerative ability of cartilaginous tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of plasma anti-elastin antibodies for use as a diagnostic aid for chronic progressive lymphoedema in Belgian Draught Horses.

PubMed

De Keyser, K; Berth, M; Christensen, N; Willaert, S; Janssens, S; Ducatelle, R; Goddeeris, B M; De Cock, H E V; Buys, N

2015-01-15

Diagnosis of chronic progressive lymphoedema (CPL) in draught horses, including the Belgian Draught Horse, is mainly based on clinical evaluation of typical lower limb lesions. A deficient perilymphatic elastic support, caused by a pathological elastin degradation in skin and subcutis, has been suggested as a contributing factor for CPL. Elastin degradation products induce the generation of anti-elastin Ab (AEAb), detectable in horse serum by ELISA. For a clinically healthy group of draught horses, a significantly lower average AEAb-level than 3 clinically affected groups (mild, moderate and severe symptoms) was demonstrated previously. To improve CPL-diagnosis, we evaluated the AEAb-ELISA as an in vitro diagnostic aid in individual horses. Test reproducibility was assessed, performing assays independently in 2 laboratories on a total of 345 horses. Possible factors associated with AEAb-levels (age, gender, pregnancy, test lab and date of blood collection) were analyzed using a mixed statistical model. Results were reproducible in both laboratories. AEAb-levels in moderately and severely affected horses were significantly higher than in healthy horses. Nevertheless, this was only demonstrated in barren mares, and, there was a very large overlap between the clinical groups. Consequently, even when a high AEAb cut-off was handled to obtain a reasonable specificity of 90%, a very low sensitivity (21%) of AEAb for CPL-diagnosis was obtained. Results on the present sample demonstrate that the described ELISA procedure is of no use as a diagnostic test for CPL in individual horses. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular Mechanisms of Stress-Responsive Changes in Collagen and Elastin Networks in Skin.

PubMed

Aziz, Jazli; Shezali, Hafiz; Radzi, Zamri; Yahya, Noor Azlin; Abu Kassim, Noor Hayaty; Czernuszka, Jan; Rahman, Mohammad Tariqur

2016-01-01

Collagen and elastin networks make up the majority of the extracellular matrix in many organs, such as the skin. The mechanisms which are involved in the maintenance of homeostatic equilibrium of these networks are numerous, involving the regulation of genetic expression, growth factor secretion, signalling pathways, secondary messaging systems, and ion channel activity. However, many factors are capable of disrupting these pathways, which leads to an imbalance of homeostatic equilibrium. Ultimately, this leads to changes in the physical nature of skin, both functionally and cosmetically. Although various factors have been identified, including carcinogenesis, ultraviolet exposure, and mechanical stretching of skin, it was discovered that many of them affect similar components of regulatory pathways, such as fibroblasts, lysyl oxidase, and fibronectin. Additionally, it was discovered that the various regulatory pathways intersect with each other at various stages instead of working independently of each other. This review paper proposes a model which elucidates how these molecular pathways intersect with one another, and how various internal and external factors can disrupt these pathways, ultimately leading to a disruption in collagen and elastin networks. © 2016 S. Karger AG, Basel.

Characterization of atherosclerotic plaques by cross-polarization optical coherence tomography

NASA Astrophysics Data System (ADS)

Gubarkova, Ekaterina V.; Dudenkova, Varvara V.; Feldchtein, Felix I.; Timofeeva, Lidia B.; Kiseleva, Elena B.; Kuznetsov, Sergei S.; Moiseev, Alexander A.; Gelikonov, Gregory V.; Vitkin, Alex I.; Gladkova, Natalia D.

2016-02-01

We combined cross-polarization optical coherence tomography (CP OCT) and non-linear microscopy based on second harmonic generation (SHG) and two-photon-excited fluorescence (2PEF) to assess collagen and elastin fibers in the development of the atherosclerotic plaque (AP). The study shows potential of CP OCT for the assessment of collagen and elastin fibers condition in atherosclerotic arteries. Specifically, the additional information afforded by CP OCT, related to birefringence and cross-scattering properties of arterial tissues, may improve the robustness and accuracy of assessment about the microstructure and composition of the plaque for different stages of atherosclerosis.

Determination of cellulose crystallinity from powder diffraction diagrams: Powder Diffraction Diagrams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindner, Benjamin; Petridis, Loukas; Langan, Paul

2014-10-01

Commonly one-dimensional (1D) (spherically averaged) powder diffraction diagrams are used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. Moreover, this leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrilsmore » with crystalline segments as amorphous. Finally, the reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation.« less

Advances in Surface Plasmon Resonance Imaging allowing for quantitative measurement of laterally heterogeneous samples

NASA Astrophysics Data System (ADS)

Raegen, Adam; Reiter, Kyle; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2012-02-01

The Surface Plasmon Resonance (SPR) phenomenon is routinely exploited to qualitatively probe changes to materials on metallic surfaces for use in probes and sensors. Unfortunately, extracting truly quantitative information is usually limited to a select few cases -- uniform absorption/desorption of small biomolecules and films, in which a continuous ``slab'' model is a good approximation. We present advancements in the SPR technique that expand the number of cases for which the technique can provide meaningful results. Use of a custom, angle-scanning SPR imaging system, together with a refined data analysis method, allow for quantitative kinetic measurements of laterally heterogeneous systems. The degradation of cellulose microfibrils and bundles of microfibrils due to the action of cellulolytic enzymes will be presented as an excellent example of the capabilities of the SPR imaging system.

Deformation and failure mechanism of secondary cell wall in Spruce late wood

NASA Astrophysics Data System (ADS)

Adusumalli, Ramesh-Babu; Raghavan, Rejin; Ghisleni, Rudy; Zimmermann, Tanja; Michler, Johann

2010-08-01

The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure. With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear or kink band.

Losartan and captopril treatment rescue normal thrombus formation in microfibril associated glycoprotein-1 (MAGP1) deficient mice.

PubMed

Vassequi-Silva, Tallita; Pereira, Danielle Sousa; Nery Diez, Ana Cláudia C; Braga, Guilherme G; Godoy, Juliana A; Mendes, Camila B; Dos Santos, Leonardo; Krieger, José E; Antunes, Edson; Costa, Fábio T M; Vicente, Cristina P; Werneck, Claudio C

2016-02-01

MAGP1 is a glycoprotein present in the elastic fibers and is a part of the microfibrils components. MAGP1 interacts with von Willebrand factor and the active form of TGF-β and BMP. In mice lacking MAGP1, thrombus formation is delayed, increasing the occlusion time of carotid artery despite presenting normal blood coagulation in vitro. MAGP1-containing microfibrils may play a role in hemostasis and thrombosis. In this work, we evaluated the function of MAGP1 and its relation to TGF-β in the arterial thrombosis process. We analyzed thrombus formation time in wild type and MAGP1-deficient mice comparing Rose Bengal and Ferric Chloride induced arterial lesion. The potential participation of TGF-β in this process was accessed when we treated both wild type and MAGP1-deficient mice with losartan (an antihypertensive drug that decreases TGF-β activity) or captopril (an angiotensin converting enzyme inhibitor that was used as a control antihypertensive drug). Besides, we evaluated thrombus embolization and the gelatinolytic activity in the arterial walls in vitro and ex vivo. Losartan and captopril were able to recover the thrombus formation time without changing blood pressure, activated partial thromboplastin time (aPTT), PT (prothrombin time), platelet aggregation and adhesion, but decreased gelatinase activity. Our results suggest that both treatments are effective in the prevention of the sub-endothelial ECM degradation, allowing the recovery of normal thrombus formation. Copyright © 2015 Elsevier Ltd. All rights reserved.

On the role of stress anisotropy in the growth of stems.

PubMed

Baskin, Tobias I; Jensen, Oliver E

2013-11-01

We review the role of anisotropic stress in controlling the growth anisotropy of stems. Instead of stress, growth anisotropy is usually considered in terms of compliance. Anisotropic compliance is typical of cell walls, because they contain aligned cellulose microfibrils, and it appears to be sufficient to explain the growth anisotropy of an isolated cell. Nevertheless, a role for anisotropic stress in the growth of stems is indicated by certain growth responses that appear too rapid to be accounted for by changes in cell-wall compliance and because the outer epidermal wall of most growing stems has microfibrils aligned axially, an arrangement that would favour radial expansion based on cell-wall compliance alone. Efforts to quantify stress anisotropy in the stem have found that it is predominantly axial, and large enough in principle to explain the elongation of the epidermis, despite its axial microfibrils. That the epidermis experiences a stress deriving from the inner tissue, the so-called 'tissue stress', has been widely recognized; however, the origin of the dominant axial direction remains obscure. Based on geometry, an isolated cylindrical cell should have an intramural stress anisotropy favouring the transverse direction. Explanations for tissue stress have invoked differential elastic moduli, differential plastic deformation (so-called differential growth), and a phenomenon analogous to the maturation stress generated by secondary cell walls. None of these explanations has been validated. We suggest that understanding the role of stress anisotropy in plant growth requires a deeper understanding of the nature of stress in hierarchical, organic structures.

Nitric oxide donor restores lung growth factor and receptor expression in hyperoxia-exposed rat pups.

PubMed

Lopez, Emmanuel; Boucherat, Olivier; Franco-Montoya, Marie-Laure; Bourbon, Jacques R; Delacourt, Christophe; Jarreau, Pierre-Henri

2006-06-01

Exposure of newborn rats to hyperoxia impairs alveolarization. Nitric oxide (NO) may prevent this evolution. Angiogenesis and factors involved in this process, but also other growth factors (GFs) involved in alveolar development, are likely potential therapeutic targets for NO. We studied the effects of the NO donor, [Z]-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)aminio]diazen-1-ium-1, 2-diolate, also termed DETANONOate (D-NO), on hyperoxia-induced changes in key regulatory factors of alveolar development in neonatal rats, and its possible preventive effect on the physiologic consequences of hyperoxia. Newborn rat pups were randomized at birth to hyperoxia (> 95% O2) or room air exposure for 6 or 10 d, while receiving D-NO or its diluent. On Day 6, several GFs and their receptors were studied at pre- and/or post-translational levels. Elastin transcript determination on Day 6, and elastin deposition in tissue and morphometric analysis of the lungs on Day 10, were also performed. Hyperoxia decreased the expression of vascular endothelial growth factor (VEGF) receptor (VEGFR) 2, fibroblast growth factor (FGF)-18, and FGF receptors (FGFRs) FGFR3 and FGFR4, increased mortality, and impaired alveolarization and capillary growth. D-NO treatment of hyperoxia-exposed pups restored the expression level of FGF18 and FGFR4, induced an increase of both VEGF mRNA and protein, enhanced elastin expression, and partially restored elastin deposition in alveolar walls. Although, under the present conditions, D-NO failed to prevent the physiologic consequences of hyperoxia in terms of survival and lung alveolarization, our findings demonstrate molecular effects of NO on GFs involved in alveolar development that may have contributed to the protective effects previously reported for NO.

Evidence for age-dependent air-space enlargement contributing to loss of lung tissue elastic recoil pressure and increased shear modulus in older age.

PubMed

Subramaniam, K; Kumar, H; Tawhai, M H

2017-07-01

As a normal part of mature aging, lung tissue undergoes microstructural changes such as alveolar air-space enlargement and redistribution of collagen and elastin away from the alveolar duct. The older lung also experiences an associated decrease in elastic recoil pressure and an increase in specific tissue elastic moduli, but how this relates mechanistically to microstructural remodeling is not well-understood. In this study, we use a structure-based mechanics analysis to elucidate the contributions of age-related air-space enlargement and redistribution of elastin and collagen to loss of lung elastic recoil pressure and increase in tissue elastic moduli. Our results show that age-related geometric changes can result in reduction of elastic recoil pressure and increase in shear and bulk moduli, which is consistent with published experimental data. All elastic moduli were sensitive to the distribution of stiffness (representing elastic fiber density) in the alveolar wall, with homogenous stiffness near the duct and through the septae resulting in a more compliant tissue. The preferential distribution of elastic proteins around the alveolar duct in the healthy young adult lung therefore provides for a more elastic tissue. NEW & NOTEWORTHY We use a structure-based mechanics analysis to correlate air-space enlargement and redistribution of elastin and collagen to age-related changes in the mechanical behavior of lung parenchyma. Our study highlights that both the cause (redistribution of elastin and collagen) and the structural effect (alveolar air-space enlargement) contribute to decline in lung tissue elastic recoil with age; these results are consistent with published data and provide a new avenue for understanding the mechanics of the older lung. Copyright © 2017 the American Physiological Society.

Segmental and age differences in the elastin network, collagen, and smooth muscle phenotype in the tunica media of the porcine aorta.

PubMed

Tonar, Zbyněk; Kubíková, Tereza; Prior, Claudia; Demjén, Erna; Liška, Václav; Králíčková, Milena; Witter, Kirsti

2015-09-01

The porcine aorta is often used in studies on morphology, pathology, transplantation surgery, vascular and endovascular surgery, and biomechanics of the large arteries. Using quantitative histology and stereology, we estimated the area fraction of elastin, collagen, alpha-smooth muscle actin, vimentin, and desmin within the tunica media in 123 tissue samples collected from five segments (thoracic ascending aorta; aortic arch; thoracic descending aorta; suprarenal abdominal aorta; and infrarenal abdominal aorta) of porcine aortae from growing domestic pigs (n=25), ranging in age from 0 to 230 days. The descending thoracic aorta had the greatest elastin fraction, which decreased proximally toward the aortic arch as well as distally toward the abdominal aorta. Abdominal aortic segments had the highest fraction of actin, desmin, and vimentin positivity and all of these vascular smooth muscle markers were lower in the thoracic aortic segments. No quantitative differences were found when comparing the suprarenal abdominal segments with the infrarenal abdominal segments. The area fraction of actin within the media was comparable in all age groups and it was proportional to the postnatal growth. Thicker aortic segments had more elastin and collagen with fewer contractile cells. The collagen fraction decreased from ascending aorta and aortic arch toward the descending aorta. By revealing the variability of the quantitative composition of the porcine aorta, the results are suitable for planning experiments with the porcine aorta as a model, i.e. power test analyses and estimating the number of samples necessary to achieving a desirable level of precision. The complete primary morphometric data, in the form of continuous variables, are made publicly available for biomechanical modeling of site-dependent distensibility and compliance of the porcine aorta. Copyright © 2015 Elsevier GmbH. All rights reserved.

An In Vivo Study of Composite Microgels Based on Hyaluronic Acid and Gelatin for the Reconstruction of Surgically Injured Rat Vocal Folds

PubMed Central

Coppoolse, Jiska M. S.; Van Kooten, T. G.; Heris, Hossein K.; Mongeau, Luc; Li, Nicole Y. K.; Thibeault, Susan L.; Pitaro, Jacob; Akinpelu, Olubunmi; Daniel, Sam J.

2016-01-01

Purpose The objective of this study was to investigate local injection with a hierarchically microstructured hyaluronic acid–gelatin (HA-Ge) hydrogel for the treatment of acute vocal fold injury using a rat model. Method Vocal fold stripping was performed unilaterally in 108 Sprague-Dawley rats. A volume of 25 ml saline (placebo controls), HA-bulk, or HA-Ge hydrogel was injected into the lamina propria (LP) 5 days after surgery. The vocal folds were harvested at 3, 14, and 28 days after injection and analyzed using hematoxylin and eosin staining and immunohistochemistry staining for macrophages, myofibroblasts, elastin, collagen type I, and collagen type III. Results The macrophage count was statistically significantly lower in the HA-Ge group than in the saline group (p < .05) at Day 28. Results suggested that the HA-Ge injection did not induce inflammatory or rejection response. Myofibroblast counts and elastin were statistically insignificant across treatment groups at all time points. Increased elastin deposition was qualitatively observed in both HA groups from Day 3 to Day 28, and not in the saline group. Significantly more elastin was observed in the HA-bulk group than in the uninjured group at Day 28. Significantly more collagen type I was observed in the HA-bulk and HA-Ge groups than in the saline group (p < .05) at Day 28. The collagen type I concentration in the HA-Ge and saline groups was found to be comparable to that in the uninjured controls at Day 28. The concentration of collagen type III in all treatment groups was similar to that in uninjured controls at Day 28. Conclusion Local HA-Ge and HA-bulk injections for acute injured vocal folds were biocompatible and did not induce adverse response. PMID:24687141

Brain arterial aging and its relationship to Alzheimer dementia

PubMed Central

Honig, Lawrence; Elkind, Mitchell S.V.; Mohr, Jay P.; Goldman, James; Dwork, Andrew J.; Morgello, Susan; Marshall, Randolph S.

2016-01-01

Objective: To test the hypothesis that brain arterial aging is associated with the pathologic diagnosis of Alzheimer disease (AD). Methods: Brain large arteries were assessed for diameter, gaps in the internal elastic lamina (IEL), luminal stenosis, atherosclerosis, and lumen-to-wall ratio. Elastin, collagen, and amyloid were assessed with Van Gieson, trichrome, and Congo red staining intensities, and quantified automatically. Brain infarcts and AD (defined pathologically) were assessed at autopsy. We created a brain arterial aging (BAA) score with arterial characteristics associated with aging after adjusting for demographic and clinical variables using cross-sectional generalized linear models. Results: We studied 194 autopsied brains, 25 (13%) of which had autopsy evidence of AD. Brain arterial aging consisted of higher interadventitial and lumen diameters, thickening of the wall, increased prevalence of IEL gaps, concentric intima thickening, elastin loss, increased amyloid deposition, and a higher IEL proportion without changes in lumen-to-wall ratio. In multivariable analysis, a high IEL proportion (B = 1.96, p = 0.030), thick media (B = 3.50, p = 0.001), elastin loss (B = 6.16, p < 0.001), IEL gaps (B = 3.14, p = 0.023), and concentric intima thickening (B = 7.19, p < 0.001) were used to create the BAA score. Adjusting for demographics, vascular risk factors, atherosclerosis, and brain infarcts, the BAA score was associated with AD (B = 0.022, p = 0.002). Conclusions: Aging of brain large arteries is characterized by arterial dilation with a commensurate wall thickening, elastin loss, and IEL gaps. Greater intensity of arterial aging was associated with AD independently of atherosclerosis and brain infarcts. Understanding the drivers of arterial aging may advance the knowledge of the pathophysiology of AD. PMID:26984942

Brain arterial aging and its relationship to Alzheimer dementia.

PubMed

Gutierrez, Jose; Honig, Lawrence; Elkind, Mitchell S V; Mohr, Jay P; Goldman, James; Dwork, Andrew J; Morgello, Susan; Marshall, Randolph S

2016-04-19

To test the hypothesis that brain arterial aging is associated with the pathologic diagnosis of Alzheimer disease (AD). Brain large arteries were assessed for diameter, gaps in the internal elastic lamina (IEL), luminal stenosis, atherosclerosis, and lumen-to-wall ratio. Elastin, collagen, and amyloid were assessed with Van Gieson, trichrome, and Congo red staining intensities, and quantified automatically. Brain infarcts and AD (defined pathologically) were assessed at autopsy. We created a brain arterial aging (BAA) score with arterial characteristics associated with aging after adjusting for demographic and clinical variables using cross-sectional generalized linear models. We studied 194 autopsied brains, 25 (13%) of which had autopsy evidence of AD. Brain arterial aging consisted of higher interadventitial and lumen diameters, thickening of the wall, increased prevalence of IEL gaps, concentric intima thickening, elastin loss, increased amyloid deposition, and a higher IEL proportion without changes in lumen-to-wall ratio. In multivariable analysis, a high IEL proportion (B = 1.96, p = 0.030), thick media (B = 3.50, p = 0.001), elastin loss (B = 6.16, p < 0.001), IEL gaps (B = 3.14, p = 0.023), and concentric intima thickening (B = 7.19, p < 0.001) were used to create the BAA score. Adjusting for demographics, vascular risk factors, atherosclerosis, and brain infarcts, the BAA score was associated with AD (B = 0.022, p = 0.002). Aging of brain large arteries is characterized by arterial dilation with a commensurate wall thickening, elastin loss, and IEL gaps. Greater intensity of arterial aging was associated with AD independently of atherosclerosis and brain infarcts. Understanding the drivers of arterial aging may advance the knowledge of the pathophysiology of AD. © 2016 American Academy of Neurology.

Loss of fibulin-4 disrupts collagen synthesis and maturation: implications for pathology resulting from EFEMP2 mutations

PubMed Central

Papke, Christina L.; Tsunezumi, Jun; Ringuette, Léa-Jeanne; Nagaoka, Hideaki; Terajima, Masahiko; Yamashiro, Yoshito; Urquhart, Greg; Yamauchi, Mitsuo; Davis, Elaine C.; Yanagisawa, Hiromi

2015-01-01

Homozygous recessive mutations in either EFEMP2 (encoding fibulin-4) or FBLN5 (encoding fibulin-5), critical genes for elastogenesis, lead to autosomal recessive cutis laxa types 1B and 1A, respectively. Previously, fibulin-4 was shown to bind lysyl oxidase (LOX), an elastin/collagen cross-linking enzyme, in vitro. Consistently, reported defects in humans with EFEMP2 mutations are more severe and broad in range than those due to FBLN5 mutations and encompass both elastin-rich and collagen-rich tissues. However, the underlying disease mechanism in EFEMP2 mutations has not been fully addressed. Here, we show that fibulin-4 is important for the integrity of aortic collagen in addition to elastin. Smooth muscle-specific Efemp2 loss in mouse (termed SMKO) resulted in altered fibrillar collagen localization with larger, poorly organized fibrils. LOX activity was decreased in Efemp2-null cells, and collagen cross-linking was diminished in SMKO aortas; however, elastin cross-linking was unaffected and the level of mature LOX was maintained to that of wild-type aortas. Proteomic screening identified multiple proteins involved in procollagen processing and maturation as potential fibulin-4-binding partners. We showed that fibulin-4 binds procollagen C-endopeptidase enhancer 1 (Pcolce), which enhances proteolytic cleavage of the procollagen C-terminal propeptide during procollagen processing. Interestingly, however, procollagen cleavage was not affected by the presence or absence of fibulin-4 in vitro. Thus, our data indicate that fibulin-4 serves as a potential scaffolding protein during collagen maturation in the extracellular space. Analysis of collagen in other tissues affected by fibulin-4 loss should further increase our understanding of underlying pathologic mechanisms in patients with EFEMP2 mutations. PMID:26220971

Prevention of abdominal aortic aneurysm progression by targeted inhibition of matrix metalloproteinase activity with batimastat-loaded nanoparticles.

PubMed

Nosoudi, Nasim; Nahar-Gohad, Pranjal; Sinha, Aditi; Chowdhury, Aniqa; Gerard, Patrick; Carsten, Christopher G; Gray, Bruce H; Vyavahare, Naren R

2015-11-06

Matrix metalloproteinases (MMPs)-mediated extracellular matrix destruction is the major cause of development and progression of abdominal aortic aneurysms. Systemic treatments of MMP inhibitors have shown effectiveness in animal models, but it did not translate to clinical success either because of low doses used or systemic side effects of MMP inhibitors. We propose a targeted nanoparticle (NP)-based delivery of MMP inhibitor at low doses to the abdominal aortic aneurysms site. Such therapy will be an attractive option for preventing expansion of aneurysms in patients without systemic side effects. Our previous study showed that poly(d,l-lactide) NPs conjugated with an antielastin antibody could be targeted to the site of an aneurysm in a rat model of abdominal aortic aneurysms. In the study reported here, we tested whether such targeted NPs could deliver the MMP inhibitor batimastat (BB-94) to the site of an aneurysm and prevent aneurysmal growth. Poly(d,l-lactide) NPs were loaded with BB-94 and conjugated with an elastin antibody. Intravenous injections of elastin antibody-conjugated BB-94-loaded NPs targeted the site of aneurysms and delivered BB-94 in a calcium chloride injury-induced abdominal aortic aneurysms in rats. Such targeted delivery inhibited MMP activity, elastin degradation, calcification, and aneurysmal development in the aorta (269% expansion in control versus 40% elastin antibody-conjugated BB-94-loaded NPs) at a low dose of BB-94. The systemic administration of BB-94 alone at the same dose was ineffective in producing MMP inhibition. Targeted delivery of MMP inhibitors using NPs may be an attractive strategy to inhibit aneurysmal progression. © 2015 American Heart Association, Inc.

Multicolor Luminescence from Conjugates of Genetically Encoded Elastin-like Polymers and Terpyridine-Lanthanides

DOE PAGES

Ghosh, Koushik; Balog, Eva Rose M.; Kahn, Jennifer L.; ...

2015-08-20

Functional hybrid materials with optically active metal-ligand moieties embedded within a polymer matrix have a great potential in (bio)materials science, including applications in light-emitting diode devices. Here, we report a simple strategy to incorporate terpyridine derivatives into the side chains of elastin-like polymers (ELPs). The further binding of trivalent lanthanide ions with the terpyridine ligands generated an array of photoluminescence ranging from the visible to the near-infrared regions. Lastly, as thin films, these ELP-based optical materials also exhibited distinct morphologies that depend upon the temperature of the aqueous solutions from which the hybrid polymers were spin coated or drop cast.

Expression and purification of short hydrophobic elastin-like polypeptides with maltose-binding protein as a solubility tag.

PubMed

Bataille, Laure; Dieryck, Wilfrid; Hocquellet, Agnès; Cabanne, Charlotte; Bathany, Katell; Lecommandoux, Sébastien; Garbay, Bertrand; Garanger, Elisabeth

2015-06-01

Elastin-like polypeptides (ELPs) are biodegradable polymers with interesting physico-chemical properties for biomedical and biotechnological applications. The recombinant expression of hydrophobic elastin-like polypeptides is often difficult because they possess low transition temperatures, and therefore form aggregates at sub-ambient temperatures. To circumvent this difficulty, we expressed in Escherichia coli three hydrophobic ELPs (VPGIG)n with variable lengths (n=20, 40, and 60) in fusion with the maltose-binding protein (MBP). Fusion proteins were soluble and yields of purified MBP-ELP ranged between 66 and 127mg/L culture. After digestion of the fusion proteins by enterokinase, the ELP moiety was purified by using inverse transition cycling. The purified fraction containing ELP40 was slightly contaminated by traces of undigested fusion protein. Purification of ELP60 was impaired because of co-purification of the MBP tag during inverse transition cycling. ELP20 was successfully purified to homogeneity, as assessed by gel electrophoresis and mass spectrometry analyses. The transition temperature of ELP20 was measured at 15.4°C in low salt buffer. In conclusion, this method can be used to produce hydrophobic ELP of low molecular mass. Copyright © 2015 Elsevier Inc. All rights reserved.

Elastin Degradation by Cathepsin V Requires Two Exosites*

PubMed Central

Du, Xin; Chen, Nelson L. H.; Wong, Andre; Craik, Charles S.; Brömme, Dieter

2013-01-01

Cathepsin V is a highly effective elastase and has been implicated in physiological and pathological extracellular matrix degradation. However, its mechanism of action remains elusive. Whereas human cathepsin V exhibits a potent elastolytic activity, the structurally homologous cathepsin L, which shares a 78% amino acid sequence, has only a minimal proteolytic activity toward insoluble elastin. This suggests that there are distinct structural domains that play an important role in elastinolysis. In this study, a total of 11 chimeras of cathepsins V and L were generated to identify elastin-binding domains in cathepsin V. Evaluation of these chimeras revealed two exosites contributing to the elastolytic activity of cathepsin V that are distant from the active cleft of the protease and are located in surface loop regions. Replacement of exosite 1 or 2 with analogous residues from cathepsin L led to a 75 and 43% loss in the elastolytic activity, respectively. Replacement of both exosites yielded a non-elastase variant similar to that of cathepsin L. Identification of these exosites may contribute to the design of inhibitors that will only affect the elastolytic activity of cysteine cathepsins without interfering with other physiological protease functions. PMID:24121514

Semicarbazide-sensitive amine oxidase and extracellular matrix deposition by smooth-muscle cells

NASA Technical Reports Server (NTRS)

Langford, Shannon D.; Trent, Margaret B.; Boor, Paul J.

2002-01-01

We have recently reported in vivo disruption of collagen and elastin architecture within blood vessel walls resulting from the selective inhibition of the enzyme semicarbazide-sensitive amine oxidase (SSAO). This study further investigates the effects of SSAO inhibition on extracellular matrix deposition by smooth-muscle cells (SMCs) cultured from neonatal rat hearts. SMCs were characterized, SSAO activity was measured, and soluble and insoluble collagen and elastin in the extracellular matrix (ECM) were quantified. Cultured neonatal rat heart SMC exhibited a monotypic synthetic phenotype that likely represents a myofibroblast. Detectable levels of SSAO activity present throughout 30-d culture peaked at 7-14 d, coinciding with the production of ECM. The addition of enzyme inhibitors and alternate SSAO substrates (benzylamine) produced varied and, in some cases, marked changes in SSAO activity as well as in the composition of mature and soluble matrix components. Similar to our previous in vivo findings, in vitro SSAO inhibition produced aberrations in collagen and elastin deposition by heart SMC. Because changes in SSAO activity are associated with cardiovascular pathologic states, this enzyme may play a protective or modulating role by regulating ECM production during pathologic insult.

Understanding Ionic Liquid Pretreatment of Lignocellulosic Biomasses

USDA-ARS?s Scientific Manuscript database

Pretreatment of biomass is essential for breaking apart highly ordered and crystalline plant cell walls and loosening the lignin and hemicellulose conjugation to cellulose microfibrills, thereby facilitating enzyme accessibility and adsorption and reducing costs of downstream saccharification proces...

MAGP1, the extracellular matrix, and metabolism

PubMed Central

Craft, Clarissa S

2014-01-01

Adipose tissue and the extracellular matrix were once considered passive players in regulating physiological processes. Now, both entities are acknowledged for their capacity to engage signal transduction pathways, and for their involvement in maintaining normal tissue homeostasis. We recently published a series of studies that identified a novel mechanism whereby an extracellular matrix molecule, MAGP1 (microfibril associated glycoprotein 1), can regulate energy metabolism in adipose tissue. MAGP1 is a component of extracellular microfibrils and plays a supportive role in maintaining thermoregulation by indirectly regulating expression of the thermogenic uncoupling proteins (UCPs). The focus of this commentary is to draw attention to the role of the extracellular matrix in regulating the bioavailability of signaling molecules, like transforming growth factor β (TGFβ), and exemplify that a better understanding of the extracellular matrix's biological properties could unveil a new source of therapeutic targets for metabolic diseases. PMID:26167404

MAGP1, the extracellular matrix, and metabolism.

PubMed

Craft, Clarissa S

2015-01-01

Adipose tissue and the extracellular matrix were once considered passive players in regulating physiological processes. Now, both entities are acknowledged for their capacity to engage signal transduction pathways, and for their involvement in maintaining normal tissue homeostasis. We recently published a series of studies that identified a novel mechanism whereby an extracellular matrix molecule, MAGP1 (microfibril associated glycoprotein 1), can regulate energy metabolism in adipose tissue. MAGP1 is a component of extracellular microfibrils and plays a supportive role in maintaining thermoregulation by indirectly regulating expression of the thermogenic uncoupling proteins (UCPs). The focus of this commentary is to draw attention to the role of the extracellular matrix in regulating the bioavailability of signaling molecules, like transforming growth factor β (TGFβ), and exemplify that a better understanding of the extracellular matrix's biological properties could unveil a new source of therapeutic targets for metabolic diseases.

Microscopic Examination of Chitosan Polyphosphate Beads with Entrapped Spores of the Biocontrol Agent, Streptomyces melanosporofaciens EF-76

NASA Astrophysics Data System (ADS)

Jobin, Guy; Grondin, Gilles; Couture, Geneviève; Beaulieu, Carole

2005-04-01

Spores of the biocontrol agent, Streptomyces melanosporofaciens EF-76, were entrapped by complex coacervation in beads composed of a macromolecular complex (MC) of chitosan and polyphosphate. A proportion of spores entrapped in beads survived the entrapment procedure as shown by treating spores from chitosan beads with a dye allowing the differentiation of live and dead cells. The spore-loaded chitosan beads could be digested by a chitosanase, suggesting that, once introduced in soil, the beads would be degraded to release the biocontrol agent. Spore-loaded beads were examined by optical and scanning electron microscopy because the release of the biological agent depends on the spore distribution in the chitosan beads. The microscopic examination revealed that the beads had a porous surface and contained a network of inner microfibrils. Spores were entrapped in both the chitosan microfibrils and the bead lacuna.

Cellulose nanocrystals, nanofibers, and their composites as renewable smart materials

NASA Astrophysics Data System (ADS)

Kim, Jaehwan; Zhai, Lindong; Mun, Seongcheol; Ko, Hyun-U.; Yun, Young-Min

2015-04-01

Cellulose is one of abundant renewable biomaterials in the world. Over 1.5 trillion tons of cellulose is produced per year in nature by biosynthesis, forming microfibrils which in turn aggregate to form cellulose fibers. Using new effective methods these microfibrils can be disintegrated from the fibers to nanosized materials, so called cellulose nanocrystal (CNC) and cellulose nanofiber (CNF). The CNC and CNF have extremely good strength properties, dimensional stability, thermal stability and good optical properties on top of their renewable behavior, which can be a building block of new materials. This paper represents recent advancement of cellulose nanocrystals and cellulose nanofibers, followed by their possibility for smart materials. Natural behaviors, extraction, modification of cellulose nanocrystals and fibers are explained and their synthesis with nanomaterials is introduced, which is necessary to meet the technological requirements for smart materials. Also, its challenges are addressed.

Multi-scale model for the hierarchical architecture of native cellulose hydrogels.

PubMed

Martínez-Sanz, Marta; Mikkelsen, Deirdre; Flanagan, Bernadine; Gidley, Michael J; Gilbert, Elliot P

2016-08-20

The structure of protiated and deuterated cellulose hydrogels has been investigated using a multi-technique approach combining small-angle scattering with diffraction, spectroscopy and microscopy. A model for the multi-scale structure of native cellulose hydrogels is proposed which highlights the essential role of water at different structural levels characterised by: (i) the existence of cellulose microfibrils containing an impermeable crystalline core surrounded by a partially hydrated paracrystalline shell, (ii) the creation of a strong network of cellulose microfibrils held together by hydrogen bonding to form cellulose ribbons and (iii) the differential behaviour of tightly bound water held within the ribbons compared to bulk solvent. Deuterium labelling provides an effective platform on which to further investigate the role of different plant cell wall polysaccharides in cellulose composite formation through the production of selectively deuterated cellulose composite hydrogels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synergy between cellulolytic enzymes during the biodegradation of cellulose microfibrils measured using angle-scanning surface plasmon resonance (SPR) imaging

NASA Astrophysics Data System (ADS)

Raegen, Adam; Dion, Alexander; Reiter, Kyle; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2014-03-01

The use of cellulosic ethanol, a promising emerging energy source, is limited by the energy intensive and costly step of first converting the cellulose fibers into their constituent glucose monomers. Industrial processes mimic those that occur in nature, using mixtures or ``cocktails'' of different classes of cellulolytic enzymes derived from fungi. Despite several decades of investigation, the molecular mechanisms for enzyme synergy remain poorly understood. To gain additional insight, we have used a custom angle-scanning surface plasmon resonance (SPR) imaging apparatus to obtain a sensitive measure of enzymatic degradation. By implementing a novel SPR data analysis procedure, we have been able to track the thickness and roughness of laterally heterogeneous cellulose microfibril-coated substrates as enzymatic degradation proceeds. This has allowed us to measure the synergistic actions of the different enzymes, providing data that are directly relevant to the cellulosic ethanol industry.

Dispersions of attractive semiflexible fiberlike colloidal particles from bacterial cellulose microfibrils.

PubMed

Kuijk, Anke; Koppert, Remco; Versluis, Peter; van Dalen, Gerard; Remijn, Caroline; Hazekamp, Johan; Nijsse, Jaap; Velikov, Krassimir P

2013-11-26

We prepared dispersions from bacterial cellulose microfibrils (CMF) of a commercial Nata de Coco source. We used an ultra-high-energy mechanical deagglomeration process that is able to disperse the CMFs from the pellicle in which they are organized in an irregular network. Because of the strong attractions between the CMFs, the dispersion remained highly heterogeneous, consisting of fiber bundles, flocs, and voids spanning tens to hundreds of micrometers depending on concentration. The size of these flocs increased with CMF concentration, the size of the bundles stayed constant, and the size of the voids decreased. The observed percolation threshold in MFC dispersions is lower than the theoretical prediction, which is accounted for by the attractive interactions in the system. Because bacterial cellulose is chemically very pure, it can be used to study the interaction of attractive and highly shape-anisotropic, semiflexible fiberlike colloidal particles.

Architecturally defined scaffolds from synthetic collagen and elastin analogues for the fabrication of bioengineered tissues

NASA Astrophysics Data System (ADS)

Caves, Jeffrey Morris

The microstructure and mechanics of collagen and elastin protein fiber networks dictate the mechanical responses of all soft tissues and related organ systems. In this project, we endeavored to meet or exceed native tissue biomechanical properties through mimicry of these extracellular matrix components with synthetic collagen fiber and a recombinant elastin-like protein polymer. Significantly, this work led to the development of a framework for the design and fabrication of protein-based tissue substitutes with enhanced strength, resilience, anisotropy, and more. We began with the development of a spinning process for scalable production of synthetic collagen fiber. Fiber with an elliptical cross-section of 53 +/- 14 by 21 +/- 3 mum and an ultimate tensile strength of 90 +/- 19 MPa was continuously produced at 60 meters per hour from an ultrafiltered collagen solution. The starting collagen concentration, flowrate, and needle size could be adjusted to control fiber size. The fiber was characterized with mechanical analysis, micro-differential scanning calorimetry, transmission electron microscopy, second harmonic generation analysis, and subcutaneous murine implant. We subsequently describe the scalable, semi-automated fabrication of elastin-like protein sheets reinforced with synthetic collagen fibers that can be positioned in a precisely defined three-dimensional hierarchical pattern. Multilamellar, fiber-reinforced elastic protein sheets were constructed with controlled fiber orientation and volume fraction. Structures were analyzed with scanning electron microscopy, transmission electron microscopy, and digital volumetric imaging. The effect of fiber orientation and volume fraction on Young's Modulus, yield stress, ultimate tensile stress, strain-to-failure, and resilience was evaluated in uniaxial tension. Increased fiber volume fraction and alignment with applied deformation significantly increased Young's Modulus, resilience, and yield stress. Highly extensible, elastic tissues display a functionally important mechanical transition from low to high modulus deformation at a strain dictated by the crimped microstructure of native collagen fiber. We report the fabrication of dense arrays of microcrimped synthetic collagen fiber embedded in elastin-like protein lamellae that mimic this aspect of tissue mechanics. Microcrimped fiber arrays were characterized with scanning electron microscopy, confocal laser scanning microscopy, and uniaxial tension analysis. Crimp wavelength was 143 +/- 5 mum. The degree of crimping was varied from 3.1% to 9.4%, and corresponded to mechanical modulus transitions at 4.6% and 13.3% strain. Up to 1000 cycles of tensile loading did not substantially alter microcrimp morphology. We designed and prototyped a series of small-diameter vascular grafts consisting of elastin-like protein reinforced with controlled volume fractions and orientations of collagen fiber. A pressure-diameter system was developed and implemented to study the effects of fiber distribution on graft mechanics. The optimal design satisfied target properties with suture retention strength of 173 +/- 4 g-f, burst strength of 1483 +/- 143 mm Hg, and compliance of 5.1 +/- 0.8 %/100 mm Hg.

Comparison of Cellulose Iβ Simulations with Three Carbohydrate Force Fields.

PubMed

Matthews, James F; Beckham, Gregg T; Bergenstråhle-Wohlert, Malin; Brady, John W; Himmel, Michael E; Crowley, Michael F

2012-02-14

Molecular dynamics simulations of cellulose have recently become more prevalent due to increased interest in renewable energy applications, and many atomistic and coarse-grained force fields exist that can be applied to cellulose. However, to date no systematic comparison between carbohydrate force fields has been conducted for this important system. To that end, we present a molecular dynamics simulation study of hydrated, 36-chain cellulose Iβ microfibrils at room temperature with three carbohydrate force fields (CHARMM35, GLYCAM06, and Gromos 45a4) up to the near-microsecond time scale. Our results indicate that each of these simulated microfibrils diverge from the cellulose Iβ crystal structure to varying degrees under the conditions tested. The CHARMM35 and GLYCAM06 force fields eventually result in structures similar to those observed at 500 K with the same force fields, which are consistent with the experimentally observed high-temperature behavior of cellulose I. The third force field, Gromos 45a4, produces behavior significantly different from experiment, from the other two force fields, and from previously reported simulations with this force field using shorter simulation times and constrained periodic boundary conditions. For the GLYCAM06 force field, initial hydrogen-bond conformations and choice of electrostatic scaling factors significantly affect the rate of structural divergence. Our results suggest dramatically different time scales for convergence of properties of interest, which is important in the design of computational studies and comparisons to experimental data. This study highlights that further experimental and theoretical work is required to understand the structure of small diameter cellulose microfibrils typical of plant cellulose.

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hui; Wang, Tuo; Oehme, Daniel

Here, the doublet C4 peaks at ~ 85 and ~ 89 ppm in solid-state 13C NMR spectra of native cellulose have been attributed to signals of C4 atoms on the surface (solvent-exposed) and in the interior of microfibrils, designated as sC4 and iC4, respectively. The relative intensity ratios of sC4 and iC4 observed in NMR spectra of cellulose have been used to estimate the degree of crystallinity of cellulose and the number of glucan chains in cellulose microfibrils. However, the molecular structures of cellulose responsible for the specific surface and interior C4 peaks have not been positively confirmed. Using densitymore » functional theory (DFT) methods and structures produced from classical molecular dynamics simulations, we investigated how the following four factors affect 13C NMR chemical shifts in cellulose: conformations of exocyclic groups at C6 ( tg, gt and gg), H 2O molecules H-bonded on the surface of the microfibril, glycosidic bond angles (Φ, Ψ) and the distances between H4 and HO3 atoms. We focus on changes in the δ 13C4 value because it is the most significant observable for the same C atom within the cellulose structure. DFT results indicate that different conformations of the exocyclic groups at C6 have the greatest influence on δ 13C4 peak separation, while the other three factors have secondary effects that increase the spread of the calculated C4 interior and surface peaks.« less

Cell Wall Architecture of the Elongating Maize Coleoptile1

PubMed Central

Carpita, Nicholas C.; Defernez, Marianne; Findlay, Kim; Wells, Brian; Shoue, Douglas A.; Catchpole, Gareth; Wilson, Reginald H.; McCann, Maureen C.

2001-01-01

The primary walls of grasses are composed of cellulose microfibrils, glucuronoarabinoxylans (GAXs), and mixed-linkage β-glucans, together with smaller amounts of xyloglucans, glucomannans, pectins, and a network of polyphenolic substances. Chemical imaging by Fourier transform infrared microspectroscopy revealed large differences in the distributions of many chemical species between different tissues of the maize (Zea mays) coleoptile. This was confirmed by chemical analyses of isolated outer epidermal tissues compared with mesophyll-enriched preparations. Glucomannans and esterified uronic acids were more abundant in the epidermis, whereas β-glucans were more abundant in the mesophyll cells. The localization of β-glucan was confirmed by immunocytochemistry in the electron microscope and quantitative biochemical assays. We used field emission scanning electron microscopy, infrared microspectroscopy, and biochemical characterization of sequentially extracted polymers to further characterize the cell wall architecture of the epidermis. Oxidation of the phenolic network followed by dilute NaOH extraction widened the pores of the wall substantially and permitted observation by scanning electron microscopy of up to six distinct microfibrillar lamellae. Sequential chemical extraction of specific polysaccharides together with enzymic digestion of β-glucans allowed us to distinguish two distinct domains in the grass primary wall. First, a β-glucan-enriched domain, coextensive with GAXs of low degrees of arabinosyl substitution and glucomannans, is tightly associated around microfibrils. Second, a GAX that is more highly substituted with arabinosyl residues and additional glucomannan provides an interstitial domain that interconnects the β-glucan-coated microfibrils. Implications for current models that attempt to explain the biochemical and biophysical mechanism of wall loosening during cell growth are discussed. PMID:11598229

Microenvironmental Regulation by Fibrillin-1

PubMed Central

Sengle, Gerhard; Tsutsui, Ko; Keene, Douglas R.; Tufa, Sara F.; Carlson, Eric J.; Charbonneau, Noe L.; Ono, Robert N.; Sasaki, Takako; Wirtz, Mary K.; Samples, John R.; Fessler, Liselotte I.; Fessler, John H.; Sekiguchi, Kiyotoshi; Hayflick, Susan J.; Sakai, Lynn Y.

2012-01-01

Fibrillin-1 is a ubiquitous extracellular matrix molecule that sequesters latent growth factor complexes. A role for fibrillin-1 in specifying tissue microenvironments has not been elucidated, even though the concept that fibrillin-1 provides extracellular control of growth factor signaling is currently appreciated. Mutations in FBN1 are mainly responsible for the Marfan syndrome (MFS), recognized by its pleiotropic clinical features including tall stature and arachnodactyly, aortic dilatation and dissection, and ectopia lentis. Each of the many different mutations in FBN1 known to cause MFS must lead to similar clinical features through common mechanisms, proceeding principally through the activation of TGFβ signaling. Here we show that a novel FBN1 mutation in a family with Weill-Marchesani syndrome (WMS) causes thick skin, short stature, and brachydactyly when replicated in mice. WMS mice confirm that this mutation does not cause MFS. The mutation deletes three domains in fibrillin-1, abolishing a binding site utilized by ADAMTSLIKE-2, -3, -6, and papilin. Our results place these ADAMTSLIKE proteins in a molecular pathway involving fibrillin-1 and ADAMTS-10. Investigations of microfibril ultrastructure in WMS humans and mice demonstrate that modulation of the fibrillin microfibril scaffold can influence local tissue microenvironments and link fibrillin-1 function to skin homeostasis and the regulation of dermal collagen production. Hence, pathogenetic mechanisms caused by dysregulated WMS microenvironments diverge from Marfan pathogenetic mechanisms, which lead to broad activation of TGFβ signaling in multiple tissues. We conclude that local tissue-specific microenvironments, affected in WMS, are maintained by a fibrillin-1 microfibril scaffold, modulated by ADAMTSLIKE proteins in concert with ADAMTS enzymes. PMID:22242013

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

DOE PAGES

Yang, Hui; Wang, Tuo; Oehme, Daniel; ...

2017-11-02

Here, the doublet C4 peaks at ~ 85 and ~ 89 ppm in solid-state 13C NMR spectra of native cellulose have been attributed to signals of C4 atoms on the surface (solvent-exposed) and in the interior of microfibrils, designated as sC4 and iC4, respectively. The relative intensity ratios of sC4 and iC4 observed in NMR spectra of cellulose have been used to estimate the degree of crystallinity of cellulose and the number of glucan chains in cellulose microfibrils. However, the molecular structures of cellulose responsible for the specific surface and interior C4 peaks have not been positively confirmed. Using densitymore » functional theory (DFT) methods and structures produced from classical molecular dynamics simulations, we investigated how the following four factors affect 13C NMR chemical shifts in cellulose: conformations of exocyclic groups at C6 ( tg, gt and gg), H 2O molecules H-bonded on the surface of the microfibril, glycosidic bond angles (Φ, Ψ) and the distances between H4 and HO3 atoms. We focus on changes in the δ 13C4 value because it is the most significant observable for the same C atom within the cellulose structure. DFT results indicate that different conformations of the exocyclic groups at C6 have the greatest influence on δ 13C4 peak separation, while the other three factors have secondary effects that increase the spread of the calculated C4 interior and surface peaks.« less

Ocular Phenotype of Fbn2-Null Mice

PubMed Central

Shi, Yanrong; Tu, Yidong; Mecham, Robert P.; Bassnett, Steven

2013-01-01

Purpose. Fibrillin-2 (Fbn2) is the dominant fibrillin isoform expressed during development of the mouse eye. To test its role in morphogenesis, we examined the ocular phenotype of Fbn2−/− mice. Methods. Ocular morphology was assessed by confocal microscopy using antibodies against microfibril components. Results. Fbn2−/− mice had a high incidence of anterior segment dysgenesis. The iris was the most commonly affected tissue. Complete iridal coloboma was present in 37% of eyes. Dyscoria, corectopia and pseudopolycoria were also common (43% combined incidence). In wild-type (WT) mice, fibrillin-2-rich microfibrils are prominent in the pupillary membrane (PM) during development. In Fbn2-null mice, the absence of Fbn2 was partially compensated for by increased expression of fibrillin-1, although the resulting PM microfibrils were disorganized, compared with WTs. In colobomatous adult Fbn2−/− eyes, the PM failed to regress normally, especially beneath the notched region of the iris. Segments of the ciliary body were hypoplastic, and zonular fibers, although relatively plentiful, were unevenly distributed around the lens equator. In regions where the zonular fibers were particularly disturbed, the synchronous differentiation of the underlying lens fiber cells was affected. Conclusions. Fbn2 has an indispensable role in ocular morphogenesis in mice. The high incidence of iris coloboma in Fbn2-null animals implies a previously unsuspected role in optic fissure closure. The observation that fiber cell differentiation was disturbed in Fbn2−/− mice raises the possibility that the attachment of zonular fibers to the lens surface may help specify the equatorial margin of the lens epithelium. PMID:24130178

The Hygroscopic Nature of Wood,

DTIC Science & Technology

The cell walls of wood are organized as a structural system involving filamentous microfibrils , oriented essentially in the direction of the...longitudinal axis embedded in an amorphous matrix of noncrystalline cellulose , hemicelluloses, and lignin. The molecules in the amorphous regions, primarily

From nano- to micrometer scale: the role of microwave-assisted acid and alkali pretreatments in the sugarcane biomass structure.

PubMed

Isaac, Augusta; de Paula, Jéssica; Viana, Carlos Martins; Henriques, Andréia Bicalho; Malachias, Angelo; Montoro, Luciano A

2018-01-01

To date, great strides have been made in elucidating the role of thermochemical pretreatments in the chemical and structural features of plant cell walls; however, there is no clear picture of the plant recalcitrance and its relationship to deconstruction. Previous studies precluded full answers due to the challenge of multiscale features of plant cell wall organization. Complementing the previous efforts, we undertook a systematic, multiscale, and integrated approach to track the effect of microwave-assisted H 2 SO 4 and NaOH treatments on the hierarchical structure of plants, i.e., from a nano- to micrometer scale. We focused on the investigation of the highly recalcitrant sclerenchyma cell walls from sugarcane bagasse. Through atomic force microscopy and X-ray diffraction analyses, remarkable details of the assembly of cellulose microfibrils not previously seen were revealed. Following the H 2 SO 4 treatment, we observed that cellulose microfibrils were almost double the width of the alkali pretreated sample at the temperature of 160 °C. Such enlargement led to a greater contact between cellulose chains, with a subsequent molecule alignment, as indicated by the X-ray diffraction (XRD) results with the conspicuous expansion of the average crystallite size. The delignification process had little effect on the local nanometer-sized arrangement of cellulose molecules. However, the rigidity and parallel alignment of cellulose microfibrils were partially degraded. The XRD analysis also agrees with these findings as evidenced by large momentum transfer vectors ( q  > 20 nm -1 ), interpreted as indicators of the long-range order of cell wall components, which were similar for all the studied samples except with application of the NaOH treatment at 160 °C. These changes were followed by the eventual swelling of the fiber cell walls. Based on an integrated approach, we presented multidimensional architectural models of cell wall deconstruction resulting from microwave-assisted pretreatments. We provided direct evidence supporting the idea that hemicellulose is the main barrier for the swelling of cellulose microfibrils, whereas lignin adds rigidity to cell walls. Our findings shed light on the design of more efficient strategies, not only for the conversion of biomass to fuels but also for the production of nanocellulose, which has great potential for several applications such as composites, rheology modifiers, and pharmaceuticals.

Tuning Thermoresponsive Properties of Cationic Elastin-like Polypeptides by Varying Counterions and Side-Chains.

PubMed

Petitdemange, Rosine; Garanger, Elisabeth; Bataille, Laure; Bathany, Katell; Garbay, Bertrand; Deming, Timothy J; Lecommandoux, Sébastien

2017-05-17

We report the synthesis of methionine-containing recombinant elastin-like polypeptides (ELPs) of different lengths that contain periodically spaced methionine residues. These ELPs were chemoselectively alkylated at all methionine residues to give polycationic derivatives. Some of these samples were found to possess solubility transitions in water, where the temperature of these transitions varied with ELP concentration, nature of the methionine alkylating group, and nature of the sulfonium counterions. These studies show that introduction and controlled spacing of methionine sulfonium residues into ELPs can be used as a means both to tune their solubility transition temperatures in water using a variety of different parameters and to introduce new side-chain functionality.

Functional characterization of two distinct xyoglucanases from rumenal microbes

USDA-ARS?s Scientific Manuscript database

Xyloglucans are known to function by binding to cellulose microfibrils, crosslinking adjacent fibers forming cellulose-XG networks important for modulation of rigidity and extensibility of the primary cell wall of plants. Enzymatic hydrolysis and modification of xyloglucans has received considerabl...

Immune-tolerant elastin-like polypeptides (iTEPs) and their application as CTL vaccine carriers.

PubMed

Cho, S; Dong, S; Parent, K N; Chen, M

2016-01-01

Cytotoxic T lymphocyte (CTL) vaccine carriers are known to enhance the efficacy of vaccines, but a search for more effective carriers is warranted. Elastin-like polypeptides (ELPs) have been examined for many medical applications but not as CTL vaccine carriers. We aimed to create immune tolerant ELPs using a new polypeptide engineering practice and create CTL vaccine carriers using the ELPs. Four sets of novel ELPs, termed immune-tolerant elastin-like polypeptide (iTEP) were generated according to the principles dictating humoral immunogenicity of polypeptides and phase transition property of ELPs. The iTEPs were non-immunogenic in mice. Their phase transition feature was confirmed through a turbidity assay. An iTEP nanoparticle (NP) was assembled from an amphiphilic iTEP copolymer plus a CTL peptide vaccine, SIINFEKL. The NP facilitated the presentation of the vaccine by dendritic cells (DCs) and enhanced vaccine-induced CTL responses. A new ELP design and development practice was established. The non-canonical motif and the immune tolerant nature of the iTEPs broaden our insights about ELPs. ELPs, for the first time, were successfully used as carriers for CTL vaccines. It is feasible to concurrently engineer both immune-tolerant and functional peptide materials. ELPs are a promising type of CTL vaccine carriers.

Form and function of the bulbus arteriosus in yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and blue marlin (Makaira nigricans): static properties.

PubMed

Braun, Marvin H; Brill, Richard W; Gosline, John M; Jones, David R

2003-10-01

The juxtaposition of heart and gills in teleost fish means that the Windkessel function characteristic of the whole mammalian arterial tree has to be subserved by the extremely short ventral aorta and bulbus arteriosus. Over the functional pressure range, arteries from blue marlin (Makaira nigricans) and yellowfin tuna (Thunnus albacares) have J-shaped pressure-volume (P-V) loops, while bulbi from the same species have r-shaped P-V loops, with a steep initial rise followed by a compliant plateau phase. The steep initial rise in pressure is due to the geometry of the lumen. The interactions between radius, pressure and tension require a large initial pressure to open the bulbar lumen for flow. The plateau is due to the unique organization of the bulbar wall. The large elastin:collagen ratio, limited amount of collagen arranged circumferentially, lack of elastin lamellae and low hydrophobicity of the elastin itself all combine to lower stiffness, increase extensibility and allow efficient recoil. Even though the modulus of bulbus material is much lower than that of an artery, at large volumes the overall stiffness of the bulbus increases rapidly. The morphological features that give rise to the special inflation characteristics of the bulbus help to extend flow and maintain pressure during diastole.

Vitamin K deficiency: the linking pin between COPD and cardiovascular diseases?

PubMed

Piscaer, Ianthe; Wouters, Emiel F M; Vermeer, Cees; Janssens, Wim; Franssen, Frits M E; Janssen, Rob

2017-11-13

Cardiovascular diseases are prevalent in patients with chronic obstructive pulmonary disease (COPD). Their coexistence implies that many COPD patients require anticoagulation therapy. Although more and more replaced by direct oral anticoagulants, vitamin K antagonists (VKAs) are still widely used. VKAs induce profound deficiency of vitamin K, a key activator in the coagulation pathway. It is recognized however that vitamin K is also an essential cofactor in the activation of other extrahepatic proteins, such as matrix Gla protein (MGP), a potent inhibitor of arterial calcification. No or insufficient MGP activation by the use of VKAs is associated with a rapid progression of vascular calcification, which may enhance the risk for overt cardiovascular disease. Vitamin K consumption, on the other hand, seems to have a protective effect on the mineralization of arteries. Furthermore, vascular calcification mutually relates to elastin degradation, which is accelerated in patients with COPD associating with impaired survival. In this commentary, we hypothesize that vitamin K is a critical determinant to the rate of elastin degradation. We speculate on the potential link between poor vitamin K status and crucial mechanisms of COPD pathogenesis and raise concerns about the use of VKAs in patients with this disease. Future intervention studies are needed to explore if vitamin K supplementation is able to reduce elastin degradation and vascular calcification in COPD patients.

Biomechanical and morphological differences between the sclera canal ring and a peripheral sclera ring in the porcine eye.

PubMed

Terai, Naim; Schlötzer-Schrehardt, Ursula; Spoerl, Eberhard; Hornykewycz, Karin; Haentzschel, Janek; Haustein, Michael; Pillunat, Lutz E

2012-01-01

To investigate a possible association between the biomechanical load and unload behaviour and the elastin content of the sclera canal ring (SCR) and a superiorly localized sclera ring (SPS) in the porcine eye. Two sclera rings were trephined from each of 40 porcine eyes, one containing the SCR and the other an SPS. The load and the unload curves were measured in the extension range of 0-2.0 mm by a biomaterial tester. Hysteresis was determined from the area enclosed by the loading and unloading curve. Histochemical staining with resorcin-fuchsin and morphometric analysis of paraffin-embedded sections of both rings were performed to detect the area occupied by elastin fibres. At 1 mm extension, the mean load of the SCR was 0.89 ± 0.22 N and that of the SPS 1.13 ± 0.19 N, which was not significantly different between both rings (p > 0.05). Mean hysteresis in the SCR was 1.55 ± 0.30 N × mm and 1.90 ± 0.18 N × mm in the SPS, which was significantly different between both rings (p = 0.01). Mean sclera thickness was 986 μm in the SCR (range: 900-1,060 μm) and 971 μm in the SPS (range: 800-1,200 μm) without a statistically significant difference between both sclera rings (p = 0.78). The area occupied by elastin fibres was 15.5 ± 3.4% in the SCR and 4.5 ± 1.5% in the SPS, which was significantly different between both rings (p = 0.0001). Hysteresis in the SCR was significantly lower than in the SPS, indicating a higher elasticity of the SCR in the porcine eye. This effect could be explained by a higher content of elastin in the surrounding ring of the peripapillary optic nerve head providing reversible contraction in cases of intra-ocular pressure variations. Copyright © 2011 S. Karger AG, Basel.

Elastin-like-recombinamers multilayered nanofibrous scaffolds for cardiovascular applications.

PubMed

Putzu, M; Causa, F; Nele, V; de Torre, I González; Rodriguez-Cabello, J C; Netti, P A

2016-11-15

Coronary angioplasty is the most widely used technique for removing atherosclerotic plaques in blood vessels. The regeneration of the damaged intima layer after this treatment is still one of the major challenges in the field of cardiovascular tissue engineering. Different polymers have been used in scaffold manufacturing in order to improve tissue regeneration. Elastin-mimetic polymers are a new class of molecules that have been synthesized and used to obtain small diameter fibers with specific morphological characteristics. Elastin-like polymers produced by recombinant techniques and called elastin-like recombinamers (ELRs) are particularly promising due to their high degree of functionalization. Generally speaking, ELRs can show more complex molecular designs and a tighter control of their sequence than other chemically synthetized polymers Rodriguez Cabello et al (2009 Polymer 50 5159-69, 2011 Nanomedicine 6 111-22). For the fabrication of small diameter fibers, different ELRs were dissolved in 2,2,2-fluoroethanol (TFE). Dynamic light scattering was used to identify the transition temperature and get a deep characterization of the transition behavior of the recombinamers. In this work, we describe the use of electrospinning technique for the manufacturing of an elastic fibrous scaffold; the obtained fibers were characterized and their cytocompatibility was tested in vitro. A thorough study of the influence of voltage, flow rate and distance was carried out in order to determine the appropriate parameters to obtain fibrous mats without beads and defects. Moreover, using a rotating mandrel, we fabricated a tubular scaffold in which ELRs containing different cell adhesion sequences (mainly REDV and RGD) were collected. The stability of the scaffold was improved by using genipin as a crosslinking agent. Genipin-ELRs crosslinked scaffolds  show a good stability and fiber morphology. Human umbilical vein endothelial cells  were used to assess the in vitro bioactivity of the cell adhesion domains within the backbone of the ELRs.

Monitoring Process Streams Towards Understanding Ionic Liquid Pretreatment of Switchgrass and Corn Stover

USDA-ARS?s Scientific Manuscript database

Pretreatment of Biomass is essential for breaking apart highly ordered and crystalline plant cell walls and loosening the lignin and hemicellulose conjugation to cellulose microfibrils, thereby facilitating enzyme accessibility and adsorption and reducing cotsts of downstream saccharification proces...

Self-assembly of silk-elastinlike protein polymers into three-dimensional scaffolds for biomedical applications

NASA Astrophysics Data System (ADS)

Zeng, Like

Production of brand new protein-based materials with precise control over the amino acid sequences at single residue level has been made possible by genetic engineering, through which artificial genes can be developed that encode protein-based materials with desired features. As an example, silk-elastinlike protein polymers (SELPs), composed of tandem repeats of amino acid sequence motifs from Bombyx mori (silkworm) silk and mammalian elastin, have been produced in this approach. SELPs have been studied extensively in the past two decades, however, the fundamental mechanism governing the self-assembly process to date still remains largely unresolved. Further, regardless of the unprecedented success when exploited in areas including drug delivery, gene therapy, and tissue augmentation, SELPs scaffolds as a three-dimensional cell culture model system are complicated by the inability of SELPs to provide the embedded tissue cells with appropriate biochemical stimuli essential for cell survival and function. In this dissertation, it is reported that the self-assembly of silk-elastinlike protein polymers (SELPs) into nanofibers in aqueous solutions can be modulated by tuning the curing temperature, the size of the silk blocks, and the charge of the elastin blocks. A core-sheath model was proposed for nanofiber formation, with the silk blocks in the cores and the hydrated elastin blocks in the sheaths. The folding of the silk blocks into stable cores -- affected by the size of the silk blocks and the charge of the elastin blocks -- plays a critical role in the assembly of silk-elastin nanofibers. The assembled nanofibers further form nanofiber clusters on the microscale, and the nanofiber clusters then coalesce into nanofiber micro-assemblies, interconnection of which eventually leads to the formation of three-dimensional scaffolds with distinct nanoscale and microscale features. SELP-Collagen hybrid scaffolds were also fabricated to enable independent control over the scaffolds' biochemical input and matrix stiffness. It is reported herein that in the hybrid scaffolds, collagen provides essential biochemical cues needed to promote cell attachment and function while SELP imparts matrix stiffness tunability. To obtain tissue-specificity in matrix stiffness that spans over several orders of magnitude covering from soft brain to stiff cartilage, the hybrid SELP-Collagen scaffolds were crosslinked by transglutaminase at physiological conditions compatible for simultaneous cell encapsulation. The effect of the increase in matrix stiffness induced by such enzymatic crosslinking on cellular viability and proliferation was also evaluated using in vitro cell assays.

Maturation Stress Generation in Poplar Tension Wood Studied by Synchrotron Radiation Microdiffraction[C][W][OA

PubMed Central

Clair, Bruno; Alméras, Tancrède; Pilate, Gilles; Jullien, Delphine; Sugiyama, Junji; Riekel, Christian

2011-01-01

Tension wood is widespread in the organs of woody plants. During its formation, it generates a large tensile mechanical stress called maturation stress. Maturation stress performs essential biomechanical functions such as optimizing the mechanical resistance of the stem, performing adaptive movements, and ensuring the long-term stability of growing plants. Although various hypotheses have recently been proposed, the mechanism generating maturation stress is not yet fully understood. In order to discriminate between these hypotheses, we investigated structural changes in cellulose microfibrils along sequences of xylem cell differentiation in tension and normal wood of poplar (Populus deltoides × Populus trichocarpa ‘I45-51’). Synchrotron radiation microdiffraction was used to measure the evolution of the angle and lattice spacing of crystalline cellulose associated with the deposition of successive cell wall layers. Profiles of normal and tension wood were very similar in early development stages corresponding to the formation of the S1 layer and the outer part of the S2 layer. Subsequent layers were found with a lower microfibril angle (MFA), corresponding to the inner part of the S2 layer of normal wood (MFA approximately 10°) and the G layer of tension wood (MFA approximately 0°). In tension wood only, this steep decrease in MFA occurred together with an increase in cellulose lattice spacing. The relative increase in lattice spacing was found close to the usual value of maturation strains. Analysis showed that this increase in lattice spacing is at least partly due to mechanical stress induced in cellulose microfibrils soon after their deposition, suggesting that the G layer directly generates and supports the tensile maturation stress in poplar tension wood. PMID:21068364

The jiaoyao1 Mutant Is an Allele of korrigan1 That Abolishes Endoglucanase Activity and Affects the Organization of Both Cellulose Microfibrils and Microtubules in Arabidopsis[C][W

PubMed Central

Lei, Lei; Zhang, Tian; Strasser, Richard; Lee, Christopher M.; Gonneau, Martine; Mach, Lukas; Vernhettes, Samantha; Kim, Seong H.; J. Cosgrove, Daniel; Li, Shundai; Gu, Ying

2014-01-01

In higher plants, cellulose is synthesized by plasma membrane–localized cellulose synthase complexes (CSCs). Arabidopsis thaliana GH9A1/KORRIGAN1 is a membrane-bound, family 9 glycosyl hydrolase that is important for cellulose synthesis in both primary and secondary cell walls. Most previously identified korrigan1 mutants show severe phenotypes such as embryo lethality; therefore, the role of GH9A1 in cellulose synthesis remains unclear. Here, we report a novel A577V missense mutation, designated jiaoyao1 (jia1), in the second of the glycosyl hydrolase family 9 active site signature motifs in GH9A1. jia1 is defective in cell expansion in dark-grown hypocotyls, roots, and adult plants. Consistent with its defect in cell expansion, this mutation in GH9A1 resulted in reduced cellulose content and reduced CSC velocity at the plasma membrane. Green fluorescent protein–GH9A1 is associated with CSCs at multiple locations, including the plasma membrane, Golgi, trans-Golgi network, and small CESA-containing compartments or microtubule-associated cellulose synthase compartments, indicating a tight association between GH9A1 and CSCs. GH9A1A577V abolishes the endoglucanase activity of GH9A1 in vitro but does not affect its interaction with CESAs in vitro, suggesting that endoglucanase activity is important for cellulose synthesis. Interestingly, jia1 results in both cellulose microfibril and microtubule disorganization. Our study establishes the important role of endoglucanase in cellulose synthesis and cellulose microfibril organization in plants. PMID:24963054

The jiaoyao1 Mutant Is an Allele of korrigan1 That Abolishes Endoglucanase Activity and Affects the Organization of Both Cellulose Microfibrils and Microtubules in Arabidopsis.

PubMed

Lei, Lei; Zhang, Tian; Strasser, Richard; Lee, Christopher M; Gonneau, Martine; Mach, Lukas; Vernhettes, Samantha; Kim, Seong H; J Cosgrove, Daniel; Li, Shundai; Gu, Ying

2014-06-01

In higher plants, cellulose is synthesized by plasma membrane-localized cellulose synthase complexes (CSCs). Arabidopsis thaliana GH9A1/KORRIGAN1 is a membrane-bound, family 9 glycosyl hydrolase that is important for cellulose synthesis in both primary and secondary cell walls. Most previously identified korrigan1 mutants show severe phenotypes such as embryo lethality; therefore, the role of GH9A1 in cellulose synthesis remains unclear. Here, we report a novel A577V missense mutation, designated jiaoyao1 (jia1), in the second of the glycosyl hydrolase family 9 active site signature motifs in GH9A1. jia1 is defective in cell expansion in dark-grown hypocotyls, roots, and adult plants. Consistent with its defect in cell expansion, this mutation in GH9A1 resulted in reduced cellulose content and reduced CSC velocity at the plasma membrane. Green fluorescent protein-GH9A1 is associated with CSCs at multiple locations, including the plasma membrane, Golgi, trans-Golgi network, and small CESA-containing compartments or microtubule-associated cellulose synthase compartments, indicating a tight association between GH9A1 and CSCs. GH9A1 A577V abolishes the endoglucanase activity of GH9A1 in vitro but does not affect its interaction with CESAs in vitro, suggesting that endoglucanase activity is important for cellulose synthesis. Interestingly, jia1 results in both cellulose microfibril and microtubule disorganization. Our study establishes the important role of endoglucanase in cellulose synthesis and cellulose microfibril organization in plants. © 2014 American Society of Plant Biologists. All rights reserved.

Cellulose Biosynthesis: Current Views and Evolving Concepts

PubMed Central

SAXENA, INDER M.; BROWN, R. MALCOLM

2005-01-01

• Aims To outline the current state of knowledge and discuss the evolution of various viewpoints put forth to explain the mechanism of cellulose biosynthesis. • Scope Understanding the mechanism of cellulose biosynthesis is one of the major challenges in plant biology. The simplicity in the chemical structure of cellulose belies the complexities that are associated with the synthesis and assembly of this polysaccharide. Assembly of cellulose microfibrils in most organisms is visualized as a multi-step process involving a number of proteins with the key protein being the cellulose synthase catalytic sub-unit. Although genes encoding this protein have been identified in almost all cellulose synthesizing organisms, it has been a challenge in general, and more specifically in vascular plants, to demonstrate cellulose synthase activity in vitro. The assembly of glucan chains into cellulose microfibrils of specific dimensions, viewed as a spontaneous process, necessitates the assembly of synthesizing sites unique to most groups of organisms. The steps of polymerization (requiring the specific arrangement and activity of the cellulose synthase catalytic sub-units) and crystallization (directed self-assembly of glucan chains) are certainly interlinked in the formation of cellulose microfibrils. Mutants affected in cellulose biosynthesis have been identified in vascular plants. Studies on these mutants and herbicide-treated plants suggest an interesting link between the steps of polymerization and crystallization during cellulose biosynthesis. • Conclusions With the identification of a large number of genes encoding cellulose synthases and cellulose synthase-like proteins in vascular plants and the supposed role of a number of other proteins in cellulose biosynthesis, a complete understanding of this process will necessitate a wider variety of research tools and approaches than was thought to be required a few years back. PMID:15894551

Brittle Culm1, a COBRA-Like Protein, Functions in Cellulose Assembly through Binding Cellulose Microfibrils

PubMed Central

Zhang, Baocai; Liu, Xiangling; Yan, Meixian; Zhang, Lanjun; Shi, Yanyun; Zhang, Mu; Qian, Qian; Li, Jiayang; Zhou, Yihua

2013-01-01

Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1), a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI) anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM) at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD) assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs) function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity. PMID:23990797