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1.
Nat Commun ; 11(1): 5068, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033251

RESUMO

The mineralized collagen fibril is the basic building block of bone, and is commonly pictured as a parallel array of ultrathin carbonated hydroxyapatite (HAp) platelets distributed throughout the collagen. This orientation is often attributed to an epitaxial relationship between the HAp and collagen molecules inside 2D voids within the fibril. Although recent studies have questioned this model, the structural relationship between the collagen matrix and HAp, and the mechanisms by which collagen directs mineralization remain unclear. Here, we use XRD to reveal that the voids in the collagen are in fact cylindrical pores with diameters of ~2 nm, while electron microscopy shows that the HAp crystals in bone are only uniaxially oriented with respect to the collagen. From in vitro mineralization studies with HAp, CaCO3 and γ-FeOOH we conclude that confinement within these pores, together with the anisotropic growth of HAp, dictates the orientation of HAp crystals within the collagen fibril.


Assuntos
Colágeno/química , Minerais/química , Orientação Espacial , Osso e Ossos/química , Criança , Colágeno/ultraestrutura , Cristalização , Durapatita/química , Elétrons , Feminino , Humanos , Modelos Moleculares , Tomografia , Difração de Raios X
2.
Int J Nanomedicine ; 15: 4991-5004, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764931

RESUMO

Introduction: Various materials and approaches have been used to reduce the mesh-induced inflammatory response and modify the mesh with tissue-matched mechanical properties, aiming to improve the repair of abdominal wall defects. Materials and Methods: In this study, we fabricated a polycaprolactone (PCL)/silk fibroin (SF) mesh integrated with amoxicillin (AMX)-incorporating multiwalled carbon nanotubes (MWCNTs) via electrospinning, grafting and crosslinking, developing a sustainable antibiotic and flexible mesh. AMX was loaded into the hollow tubular MWCNTs by physical adsorption, and a nanofibrous structure was constructed by electrospinning PCL and SF (40:60 w/w). The AMX@MWCNTs were then chemically grafted onto the surfaces of the PCL/SF nanofibers by treating with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) solution for simultaneous crosslinking and coating. The incorporation of AMX into the MWCNTs (AMX@MWCNTs) and the integration of the AMX@MWCNTs with the PCL/SF nanofibers were characterized. Then, the functional mesh was fabricated and fully evaluated in terms of antibacterial activity, mechanical properties and host response. Results: Our results demonstrated that the PCL/SF nanofibrous structure was fabricated successfully by electrospinning. After integrating with AMX@MWCNT by grafting and crosslinking, the functional mesh showed undeformed structure, modified surface hydrophilicity and biocompatible interfaces, abdominal wall-matched mechanical properties, and a sustained-release antibiotic profile in E. coli growth inhibition compared to those of PCL/SF mesh in vitro. In a rat model with subcutaneous implantation, the functional mesh incited less mesh-induced inflammatory and foreign body responses than PCL/SF mesh within 14 days. The histological analysis revealed less infiltration of granulocytes and macrophages during this period, resulting in the loosely packed collagen deposition on the functional mesh and prominent collagen incorporation. Discussion: Therefore, this designed PCL/SF-AMX@MWCNT nanofibrous mesh, functionalized with antibacterial and tissue-matched mechanical properties, provides a promising alternative for the repair of abdominal wall defects.


Assuntos
Amoxicilina/química , Antibacterianos/química , Nanofibras/química , Nanotecnologia/métodos , Telas Cirúrgicas , Amoxicilina/farmacocinética , Amoxicilina/farmacologia , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Colágeno/química , Colágeno/metabolismo , Reagentes para Ligações Cruzadas/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fibroínas/química , Inflamação/etiologia , Masculino , Teste de Materiais , Camundongos , Nanotubos de Carbono/química , Poliésteres/química , Ratos Sprague-Dawley , Telas Cirúrgicas/efeitos adversos
3.
PLoS One ; 15(8): e0234672, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764753

RESUMO

Opticin is a class III member of the extracellular matrix small leucine-rich repeat protein/proteoglycan (SLRP) family found in vitreous humour and cartilage. It was first identified associated with the surface of vitreous collagen fibrils and several other SLRPs are also known to bind collagen fibrils and it some cases alter fibril morphology. The purpose of this study was to investigate the binding of opticin to the collagen II-containing fibrils found in vitreous and cartilage. Electron microscopic studies using gold labelling demonstrated that opticin binds vitreous and thin cartilage collagen fibrils specifically at a single site in the gap region of the collagen D-period corresponding to the e2 stain band; this is the first demonstration of the binding site of a class III SLRP on collagen fibrils. Opticin did not bind thick cartilage collagen fibrils from cartilage or tactoids formed in vitro from collagen II, but shows high specificity for thin, heterotypic collagen fibrils containing collagens II, and XI or V/XI. Vitreous collagen fibrils from opticin null and wild-type mice were compared and no difference in fibril morphology or diameter was observed. Similarly, in vitro fibrillogenesis experiments showed that opticin did not affect fibril formation. We propose that when opticin is bound to collagen fibrils, rather than influencing their morphology it instead hinders the binding of other molecules to the fibril surfaces and/or act as an intermediary bridge linking the collagen fibrils to other non-collagenous molecules.


Assuntos
Colágeno/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Proteoglicanas/metabolismo , Animais , Sítios de Ligação , Bovinos , Colágeno/química , Colágeno/ultraestrutura , Proteínas da Matriz Extracelular/química , Proteínas da Matriz Extracelular/deficiência , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Microscopia Imunoeletrônica , Ligação Proteica , Proteoglicanas/química , Proteoglicanas/deficiência , Corpo Vítreo/química , Corpo Vítreo/metabolismo , Corpo Vítreo/ultraestrutura
4.
Adv Exp Med Biol ; 1250: 3-13, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32601934

RESUMO

Collagen is an important component that makes 25-35% of our body proteins. Over the past decades, tissue engineers have been designing collagen-based biocompatible materials and studying their applications in different fields. Collagen obtained from cattle and pigs has been mainly used until now, but collagen derived from fish and other livestock has attracted more attention since the outbreak of mad cow disease, and they are also used as a raw material for cosmetics and foods. Due to the zoonotic infection using collagen derived from pigs and cattle, their application in developing biomaterials is limited; hence, the development of new animal-derived collagen is required. In addition, there is a religion (Islam, Hinduism, and Judaism) limited to export raw materials and products derived from cattle and pig. Hence, high-value collagen that is universally accessible in the world market is required. Therefore, in this review, we have dealt with the use of duck's feet-derived collagen (DC) as an emerging alternative to solve this problem and also presenting few original investigated bone regeneration results performed using DC.


Assuntos
Regeneração Óssea , Colágeno , Patos , Engenharia Tecidual , Animais , Materiais Biocompatíveis , Regeneração Óssea/fisiologia , Colágeno/química , Colágeno/metabolismo , Engenharia Tecidual/métodos , Tecidos Suporte
5.
Food Chem ; 333: 127489, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32653685

RESUMO

To improve the utilization of cod skin collagen peptides (CSCP), we heated them with xylose at 80 °C, 100 °C, and 120 °C for up to 150 min to prepare xylose-CSCP Maillard reaction products (MRPs), and then investigated their physicochemical and functional properties. The results showed that Arg, Lys, Phe, and Asp were the major amino acids involved in the Maillard reaction. After being heated at 120 °C for 150 min, the ABTS scavenging activity and reducing power of xylose-CSCP MRPs were 99.59% and 0.887 absorbance units, respectively. Xylose-CSCP MRPs had better emulsifying properties and foaming properties than CSCP. Furthermore, 26 volatile compounds, including 2,5-dimethyl-pyrazine and 2-ethyl-3,5-dimethylpyrazine, were identified from xylose-CSCP MRPs by gas chromatography-ion mobility spectrometry. Newly formed heterocyclic compounds might be responsible for the flavor and antioxidant capacity of xylose-CSCP MRPs. These results suggest the potential for xylose-CSCP MRPs to serve as functional food ingredients.


Assuntos
Fenômenos Químicos , Colágeno/química , Gadus morhua , Reação de Maillard , Peptídeos/química , Pele/química , Xilose/química , Animais , Antioxidantes/química , Temperatura Alta , Paladar
6.
PLoS One ; 15(7): e0235692, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32697783

RESUMO

Nowadays, opportunistic small predators, such as foxes (Vulpes vulpes and Vulpes lagopus), are well known to be very adaptable to human modified ecosystems. However, the timing of the start of this phenomenon in terms of human impact on ecosystems and of the implications for foxes has hardly been studied. We hypothesize that foxes can be used as an indicator of past human impact on ecosystems, as a reflection of population densities and consequently to track back the influence of humans on the Pleistocene environment. To test this hypothesis, we used stable isotope analysis (δ13C, δ15N) of bone collagen extracted from faunal remains from several archaeological sites located in the Swabian Jura (southwest Germany) and covering a time range over three important cultural periods, namely the Middle Palaeolithic (older than 42,000 years ago) attributed to Neanderthals, and the early Upper Palaeolithic periods Aurignacian and Gravettian (42,000 to 30,000 years ago) attributed to modern humans. We then ran Bayesian statistic systems (SIBER, mixSIAR) to reconstruct the trophic niches and diets of Pleistocene foxes. We observed that during the Middle Palaeolithic period, when Neanderthals sparsely populated the Swabian Jura, the niches occupied by foxes suggest a natural trophic behavior. In contrast, during the early Upper Palaeolithic periods, a new trophic fox niche appeared, characterized by a restricted diet on reindeer. This trophic niche could be due to the consumption of human subsidies related to a higher human population density and the resulting higher impact on the Pleistocene environment by modern humans compared to Neanderthals. Furthermore, our study suggests that, a synanthropic commensal behavior of foxes started already in the Aurignacian, around 42,000 years ago.


Assuntos
Dieta/veterinária , Ecossistema , Raposas/fisiologia , Animais , Arqueologia , Teorema de Bayes , Osso e Ossos/metabolismo , Isótopos de Carbono/análise , Colágeno/química , Colágeno/metabolismo , Fósseis/história , História Antiga , Humanos , Homem de Neandertal , Isótopos de Nitrogênio/análise
7.
Food Chem ; 331: 127350, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32590267

RESUMO

Fish by-products are excellent sources of collagen. Acid-soluble collagen (ASC) derived from a mixed by-product of different fish species was hydrolyzed to obtain peptide fractions and evaluate their biological and functional activities. All fractions obtained (F1: ≥30, F2: 10-30, F3: 5-10, F4: 1-5, and F5: ≤1kDa) exhibited antioxidant activity at concentrations of 5, 10, and 15 mg/mL. However, F5 registered the highest reducing power (absorbance 0.366) and hydroxyl-radical-scavenging activity (91%) at 15 mg/mL; whereas the highest DPPH scavenging activity (81%) was also detected in F5 at 5 mg/mL. The solubility of F1, F2, and F3 was ≥ 95% at pH 7. The highest foaming capacity (78%), foaming stability (60%), and emulsion stability index (42 min) were registered for F1. However, the highest emulsifying activity index (130 m2/g) was for F3. These results place collagen obtained from a mixed by-product of different fish species as a potential biotechnological alternative for the industry.


Assuntos
Antioxidantes/farmacologia , Colágeno/química , Produtos Pesqueiros , Proteínas de Peixes/química , Peptídeos/química , Peptídeos/farmacologia , Aminoácidos/análise , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Antioxidantes/química , Emulsificantes/química , Proteínas de Peixes/farmacologia , Depuradores de Radicais Livres/química , Concentração de Íons de Hidrogênio , Hidrólise , Radical Hidroxila/química , Hidrolisados de Proteína/química , Solubilidade
8.
Nat Commun ; 11(1): 2315, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32385229

RESUMO

As established nearly a century ago, mechanoradicals originate from homolytic bond scission in polymers. The existence, nature and biological relevance of mechanoradicals in proteins, instead, are unknown. We here show that mechanical stress on collagen produces radicals and subsequently reactive oxygen species, essential biological signaling molecules. Electron-paramagnetic resonance (EPR) spectroscopy of stretched rat tail tendon, atomistic molecular dynamics simulations and quantum-chemical calculations show that the radicals form by bond scission in the direct vicinity of crosslinks in collagen. Radicals migrate to adjacent clusters of aromatic residues and stabilize on oxidized tyrosyl radicals, giving rise to a distinct EPR spectrum consistent with a stable dihydroxyphenylalanine (DOPA) radical. The protein mechanoradicals, as a yet undiscovered source of oxidative stress, finally convert into hydrogen peroxide. Our study suggests collagen I to have evolved as a radical sponge against mechano-oxidative damage and proposes a mechanism for exercise-induced oxidative stress and redox-mediated pathophysiological processes.


Assuntos
Colágeno/química , Tendões/química , Animais , Materiais Biocompatíveis/química , Biopolímeros/química , Di-Hidroxifenilalanina/química , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/química , Oxirredução , Estresse Oxidativo , Ratos , Espécies Reativas de Oxigênio/química
9.
Nat Commun ; 11(1): 2416, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415208

RESUMO

Chemoresistance is a major obstacle in triple negative breast cancer (TNBC), the most aggressive breast cancer subtype. Here we identify hypoxia-induced ECM re-modeler, lysyl oxidase (LOX) as a key inducer of chemoresistance by developing chemoresistant TNBC tumors in vivo and characterizing their transcriptomes by RNA-sequencing. Inhibiting LOX reduces collagen cross-linking and fibronectin assembly, increases drug penetration, and downregulates ITGA5/FN1 expression, resulting in inhibition of FAK/Src signaling, induction of apoptosis and re-sensitization to chemotherapy. Similarly, inhibiting FAK/Src results in chemosensitization. These effects are observed in 3D-cultured cell lines, tumor organoids, chemoresistant xenografts, syngeneic tumors and PDX models. Re-expressing the hypoxia-repressed miR-142-3p, which targets HIF1A, LOX and ITGA5, causes further suppression of the HIF-1α/LOX/ITGA5/FN1 axis. Notably, higher LOX, ITGA5, or FN1, or lower miR-142-3p levels are associated with shorter survival in chemotherapy-treated TNBC patients. These results provide strong pre-clinical rationale for developing and testing LOX inhibitors to overcome chemoresistance in TNBC patients.


Assuntos
Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos , Proteína-Lisina 6-Oxidase/antagonistas & inibidores , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/enzimologia , Animais , Apoptose , Biomarcadores Tumorais/metabolismo , Linhagem Celular Tumoral , Colágeno/química , Regulação para Baixo , Matriz Extracelular/metabolismo , Feminino , Fibronectinas/metabolismo , Quinase 1 de Adesão Focal/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Hipóxia , Integrinas/metabolismo , Camundongos , Camundongos Nus , MicroRNAs/metabolismo , Transplante de Neoplasias , RNA-Seq , Transdução de Sinais
10.
PLoS One ; 15(5): e0233447, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32442194

RESUMO

The food industry is currently shown the concern with low-fat products. This study aims to evaluate the properties of oat ß-glucan(OG)-marine collagen peptide (MCP) mixed gels induced by high pressure at different ratios, pressures, pH levels and the superiority of application in the sausage. The results indicated that the typical gel with high levels of hardness, cohesiveness, springiness, and chewiness, as well as high water holding and oil adsorption capacities was formed using the OG/MCP ratio of 10:1 under 400 MPa at pH 6.0. The mixed gel replacing with 50% fat significantly increased the springiness and chewing(P<0.05), and sausages with 80% mixed gel were significantly juicier than that of the control sausage(P<0.05). Therefore, OG-MCP mixed gel could be used in the reformulation of low-fat meat products to enhance their safety and nutritional value.


Assuntos
Avena/química , Colágeno/química , Gorduras na Dieta/análise , Produtos da Carne/análise , beta-Glucanas/química , Animais , Cor , Culinária , Dieta com Restrição de Gorduras , Manipulação de Alimentos , Indústria Alimentícia , Géis , Humanos , Reologia , Sus scrofa , Paladar
11.
Int J Nanomedicine ; 15: 3039-3056, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32431500

RESUMO

Background: Electrospinning is a widely used technology that can produce scaffolds with high porosity and surface area for bone regeneration. However, the small pore sizes in electrospun scaffolds constrain cell growth and tissue-ingrowth. In this study, novel drug-loading core-shell scaffolds were fabricated via electrospinning and freeze drying to facilitate the repair of tibia bone defects in rabbit models. Materials and Methods: The collagen core scaffolds were freeze-dried containing icariin (ICA)-loaded chitosan microspheres. The shell scaffolds were electrospun using collagen, polycaprolactone and hydroxyapatite materials to form CPH composite scaffolds with the ones containing ICA microspheres named CPHI. The core-shell scaffolds were then cross-linked by genipin. The morphology, microstructure, physical and mechanical properties of the scaffolds were assessed. Rat marrow mesenchymal stem cells from the wistar rat were cultured with the scaffolds. The cell adhesion and proliferation were analysed. Adult rabbit models with tibial plateau defects were used to evaluate the performance of these scaffolds in repairing the bone defects over 4 to 12 weeks. Results: The results reveal that the novel drug-loading core-shell scaffolds were successfully fabricated, which showed good physical and chemical properties and appropriate mechanical properties. Furthermore, excellent cells attachment was observed on the CPHI scaffolds. The results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPHI scaffolds. Conclusion: These new core-shell composite scaffolds have great potential for bone tissue engineering applications and may lead to effective bone regeneration and repair.


Assuntos
Regeneração Óssea , Flavonoides/farmacologia , Tíbia/efeitos dos fármacos , Engenharia Tecidual/métodos , Tecidos Suporte/química , Animais , Regeneração Óssea/efeitos dos fármacos , Quitosana/química , Colágeno/química , Durapatita/química , Flavonoides/administração & dosagem , Flavonoides/química , Masculino , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Microesferas , Poliésteres/química , Porosidade , Coelhos , Ratos Wistar , Tíbia/diagnóstico por imagem , Microtomografia por Raio-X
12.
Food Chem ; 328: 127127, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32473492

RESUMO

Poor stability of fish hydrolyzed collagen (HC) hampers its applications, especially as food ingredients. The use of liposome as a vesicle can be a potential means to enhance bioactivities and stability of HC. HC from defatted Asian sea bass skin at different levels (0.25%-2%, w/v) were loaded into liposomes prepared from soy phosphatidylcholine (SPC) with various stabilizers (cholesterol (CHO) or glycerol (GLY)). The highest encapsulation efficiency (EE) was found in SPC-CHO-0.5%HC (P < 0.05) (85.42%), while liposome stabilized with GLY had the highest EE (74.54%) for SPC-GLY-0.25%HC (P < 0.05). After lyophilization, SPC-CHO-0.5%HC had higher EE than SPC-GLY-0.25%HC (P < 0.05). Increasing particle size and decreasing negative surface charge were found for both lyophilized samples. Lyophilized SPC-CHO-0.5%HC exhibited higher stability than lyophilized SPC-GLY-0.25%HC during storage at 25 °C for 28 days. Also, higher antioxidant activities in gastrointestinal track model system was found for SPC-CHO-0.5%HC. Thus, SPC-CHO liposome could be used as a promising carrier of HC.


Assuntos
Antioxidantes/química , Colágeno/química , Lipossomos/química , Lipossomos/farmacologia , Animais , Antioxidantes/farmacologia , Bass , Colesterol/química , Excipientes/química , Armazenamento de Alimentos , Liofilização , Trato Gastrointestinal , Glicerol , Hidrólise , Lecitinas/química , Tamanho da Partícula , Fosfatidilcolinas/química , Pele/química , Temperatura
13.
PLoS One ; 15(4): e0232180, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32343728

RESUMO

The ability to distinguish between different migratory behaviours (e.g., anadromy and potamodromy) in fish can provide important insights into the ecology, evolution, and conservation of many aquatic species. We present a simple stable carbon isotope (δ13C) approach for distinguishing between sockeye (anadromous ocean migrants) and kokanee (potamodromous freshwater residents), two migratory ecotypes of Oncorhynchus nerka (Salmonidae) that is applicable throughout most of their range across coastal regions of the North Pacific Ocean. Analyses of kokanee (n = 239) and sockeye (n = 417) from 87 sites spanning the North Pacific (Russia to California) show that anadromous and potamodromous ecotypes are broadly distinguishable on the basis of the δ13C values of their scale and bone collagen. We present three case studies demonstrating how this approach can address questions in archaeology, archival, and conservation research. Relative to conventional methods for determining migratory status, which typically apply chemical analyses to otoliths or involve genetic analyses of tissues, the δ13C approach outlined here has the benefit of being non-lethal (when applied to scales), cost-effective, widely available commercially, and should be much more broadly accessible for addressing archaeological questions since the recovery of otoliths at archaeological sites is rare.


Assuntos
Colágeno/química , Proteínas de Peixes/química , Salmão/fisiologia , Salmonidae/fisiologia , Migração Animal , Escamas de Animais/química , Animais , Arqueologia , Biodiversidade , Osso e Ossos/química , Isótopos de Carbono/análise , Conservação dos Recursos Naturais , DNA Antigo/análise , Ecótipo , Feminino , Lagos , Masculino , Oceano Pacífico , Salmão/classificação , Salmão/genética , Salmonidae/classificação , Salmonidae/genética
14.
Int J Nanomedicine ; 15: 2363-2378, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32308388

RESUMO

Biomaterials with porous structure and high surface area attract growing interest in biomedical research and applications. Aerogel-based biomaterials, as highly porous materials that are made from different sources of macromolecules, inorganic materials, and composites, mimic the structures of the biological extracellular matrix (ECM), which is a three-dimensional network of natural macromolecules (e.g., collagen and glycoproteins), and provide structural support and exert biochemical effects to surrounding cells in tissues. In recent years, the higher requirements on biomaterials significantly promote the design and development of aerogel-based biomaterials with high biocompatibility and biological activity. These biomaterials with multilevel hierarchical structures display excellent biological functions by promoting cell adhesion, proliferation, and differentiation, which are critical for biomedical applications. This review highlights and discusses the recent progress in the preparation of aerogel-based biomaterials and their biomedical applications, including wound healing, bone regeneration, and drug delivery. Moreover, the current review provides different strategies for modulating the biological performance of aerogel-based biomaterials and further sheds light on the current status of these materials in biomedical research.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Regeneração Óssea , Sistemas de Liberação de Medicamentos/métodos , Cicatrização/efeitos dos fármacos , Animais , Regeneração Óssea/efeitos dos fármacos , Colágeno/química , Matriz Extracelular/química , Matriz Extracelular/metabolismo , Humanos , Porosidade
15.
Proc Natl Acad Sci U S A ; 117(15): 8326-8334, 2020 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-32238564

RESUMO

Collagen forms the structural scaffold of connective tissues in all mammals. Tissues are remarkably resistant against mechanical deformations because collagen molecules hierarchically self-assemble in fibrous networks that stiffen with increasing strain. Nevertheless, collagen networks do fracture when tissues are overloaded or subject to pathological conditions such as aneurysms. Prior studies of the role of collagen in tissue fracture have mainly focused on tendons, which contain highly aligned bundles of collagen. By contrast, little is known about fracture of the orientationally more disordered collagen networks present in many other tissues such as skin and cartilage. Here, we combine shear rheology of reconstituted collagen networks with computer simulations to investigate the primary determinants of fracture in disordered collagen networks. We show that the fracture strain is controlled by the coordination number of the network junctions, with less connected networks fracturing at larger strains. The hierarchical structure of collagen fine-tunes the fracture strain by providing structural plasticity at the network and fiber level. Our findings imply that low connectivity and plasticity provide protective mechanisms against network fracture that can optimize the strength of biological tissues.


Assuntos
Colágeno/química , Animais , Fenômenos Biomecânicos , Bovinos , Colágeno/metabolismo , Matriz Extracelular/química , Matriz Extracelular/metabolismo , Humanos , Ratos , Reologia
16.
Nat Commun ; 11(1): 1920, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317643

RESUMO

Collagen-producing cells maintain the complex architecture of the lung and drive pathologic scarring in pulmonary fibrosis. Here we perform single-cell RNA-sequencing to identify all collagen-producing cells in normal and fibrotic lungs. We characterize multiple collagen-producing subpopulations with distinct anatomical localizations in different compartments of murine lungs. One subpopulation, characterized by expression of Cthrc1 (collagen triple helix repeat containing 1), emerges in fibrotic lungs and expresses the highest levels of collagens. Single-cell RNA-sequencing of human lungs, including those from idiopathic pulmonary fibrosis and scleroderma patients, demonstrate similar heterogeneity and CTHRC1-expressing fibroblasts present uniquely in fibrotic lungs. Immunostaining and in situ hybridization show that these cells are concentrated within fibroblastic foci. We purify collagen-producing subpopulations and find disease-relevant phenotypes of Cthrc1-expressing fibroblasts in in vitro and adoptive transfer experiments. Our atlas of collagen-producing cells provides a roadmap for studying the roles of these unique populations in homeostasis and pathologic fibrosis.


Assuntos
Colágeno/química , Pulmão/metabolismo , Fibrose Pulmonar/metabolismo , Animais , Separação Celular , Proteínas da Matriz Extracelular/metabolismo , Feminino , Fibroblastos/metabolismo , Citometria de Fluxo , Proteínas de Fluorescência Verde/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Fibrose Pulmonar Idiopática/patologia , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo , Fibrose Pulmonar/patologia , Transtornos Respiratórios/metabolismo , Análise de Célula Única
17.
PLoS One ; 15(3): e0228332, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32160199

RESUMO

Management of camelids in the coastal valleys of the Andes has generated much debate in recent years. Zooarchaeological and isotopic studies have demonstrated that in the coastal valleys of northern and southern Peru there were locally maintained camelid herds. Because of the hyperarid conditions of the northern coast of Chile, this region has been assumed to be unsuitable for the raising of camelids. In this study we report stable carbon and nitrogen isotopic compositions of camelid bone collagen and textiles made from camelid fiber from Late Intermediate Period (LIP) and Late Horizon (LH) occupations in northern Chilean river valleys. The camelid bone collagen isotopic compositions are consistent with these animals originating in the highlands, although there is a significant difference in the camelids dating to the LIP and LH, possibly because of changes made to distribution and exchange networks by the Inca in the LH. There were no differences between the isotopic compositions of the camelid fibers sampled from textiles in the LIP and LH, suggesting that either the production of camelid fiber was unchanged by the Inca or the changes that were made do not present visible isotopic evidence. Several camelid fiber samples from both the LIP and LH present very high δ13C and δ15N values, comparable to human hair samples from one site (Huancarane) in the Camarones Valley. These data suggest that people in the northern valleys of Chile may have kept small numbers of animals specifically for fiber production. Overall, however, the vast majority of the textile samples have isotopic compositions that are consistent with an origin in the highlands. These data suggest that the hyperarid coastal river valleys of northern Chile did not support substantial camelid herds as has been interpreted for northern Peru.


Assuntos
Criação de Animais Domésticos/história , Camelídeos Americanos , Fibra de Lã/história , Animais , Arqueologia , Osso e Ossos/química , Isótopos de Carbono/análise , Chile , Colágeno/química , Fósseis , História do Século XV , História do Século XVI , História Medieval , Isótopos de Nitrogênio/análise , Peru , Fibra de Lã/análise
18.
Food Chem ; 318: 126404, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32135426

RESUMO

The physicochemical properties of collagen casings were successfully improved by glutaraldehyde (GA) cross-linking, where the properties could be further regulated by drying temperature. Transverse direction (TD) showed a lower heat shrinkage rate than that in machine direction (MD). GA cross-linking significantly improved the mechanical properties of films under wet and boiled state. The mechanical properties of films in MD were more susceptible to wet and boiling water. The chemical composition was unchanged after GA cross-linking, but higher drying temperatures led to higher triple helix contents. The GA cross-linking mainly promoted the low temperature thermostability of collagen casings. All film samples had a rough fibrous morphology and a majority of collagen fibers was oriented under the lower drying temperature (55 â„ƒ). These results reported in this study can be used to better guide the preparation of collagen casings.


Assuntos
Colágeno/química , Reagentes para Ligações Cruzadas/química , Glutaral/química , Animais , Dessecação , Módulo de Elasticidade , Ligação de Hidrogênio , Conformação Proteica em alfa-Hélice , Estabilidade Proteica , Temperatura
19.
Int J Nanomedicine ; 15: 1349-1361, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32184590

RESUMO

Background: Impaired wound healing might be associated with many issues, especially overactive of reactive oxygen species (ROS), deficiency of blood vessels and immature of epidermis. N-acetylcysteine (NAC), as an antioxidant, could solve these problems by inhibiting overreactive of ROS, promoting revascularization and accelerating re-epithelialization. How to deliver NAC in situ with a controllable releasing speed still remain a challenge. Materials and Methods: In this study, we combined collagen (Col) with N-acetylcysteine to perform the characteristics of sustained release and chemically crosslinked Col/NAC composite with polyamide (PA) nanofibers to enhance the mechanical property of collagen and fabricated this multi-layered scaffold (PA-Col/NAC scaffold). The physical properties of the scaffolds such as surface characteristics, water absorption and tensile modulus were tested. Meanwhile, the ability to promote wound healing in vitro and in vivo were investigated. Results: These scaffolds were porous and performed great water absorption. The PA-Col/NAC scaffold could sustainably release NAC for at least 14 days. After cell implantation, PA-Col/NAC scaffold showed better cell proliferation and cell migration than the other groups. In vivo, PA-Col/NAC scaffolds could promote wound healing best among all the groups. Conclusion: The multi-layered scaffolds could obviously accelerate the process of wound healing and exert better and prolonged effects.


Assuntos
Acetilcisteína/farmacologia , Colágeno/química , Depuradores de Radicais Livres/farmacologia , Nylons/química , Reepitelização/efeitos dos fármacos , Tecidos Suporte/química , Cicatrização/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Preparações de Ação Retardada , Masculino , Nanofibras/química , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo
20.
Food Chem ; 319: 126598, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32182540

RESUMO

Collagens are large structural proteins that are prevalent in mammalian connective tissue. Peptides designed to include a glycine-proline-hydroxyproline (GPO) amino acid triad are biomimetic analogs of the collagen triple helix, a fold that is a hallmark of collagen-like sequences. To inform the rational engineering of collagen-like peptides and proteins for food systems, we report the crystal structure of the (GPO)10 peptide at 0.89-Å resolution, solved using direct methods. We determined that a single chain in the asymmetric unit forms a pseudo-hexagonal network of triple helices that have a pitch variation consistent with the model 7/2 helix (3.5 residues per turn). The proline rings occupied one of two states, while the helix was found to have a well-defined hydration shell involved in the stabilization of the inter-helix crystal network. This structure offers a new high-resolution basis for understanding the hierarchical assembly of native collagens, which will aid the food industry in engineering new sustainable food systems.


Assuntos
Colágeno/química , Prolina/química , Cristalografia por Raios X , Glicina , Hidroxiprolina/química , Modelos Moleculares , Fragmentos de Peptídeos/química , Conformação Proteica
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