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Perioperative hypothermia is still common and has relevant complication for the patient. An effective perioperative thermal management requires essentially an accurate method to measure core temperature. So far, only one study has investigated the new Temple Touch Pro™ (Medisim Ltd., Beit-Shemesh, Israel). during anesthesia Therefore, we assessed the agreement between the Temple Touch Pro™ thermometer (TTP) and distal esophageal temperature (TEso) in a second study. After approval by the local ethics committee we studied 100 adult patients undergoing surgery with general anesthesia. Before induction of anesthesia the TTP sensor unit was attached to the skin above the temporal artery. After induction of anesthesia an esophageal temperature probe was placed in the distal esophagus. Recordings started 10 min after placement of the esophageal temperature probe to allow adequate warming of the probes. Pairs of temperature values were documented in five-minute intervals until emergence of anesthesia. Accuracy of the two methods was assessed by Bland-Altman comparisons of differences with multiple measurements. Core temperatures obtained with the TTP in adults showed a mean bias of -0.04 °C with 95% limits of agreement within - 0.99 °C to + 0.91 °C compared to an esophageal temperature probe. We consider the TTP as a reasonable tool for perioperative temperature monitoring. It is not accurate enough to be used as a reference method in scientific studies, but may be a useful tool especially for conscious patients undergoing neuraxial anesthesia or regional anesthesia with sedation. Trial registration This study was registered in the German Clinical Trials Register (DRKS-ID: 00024050), day of registration 12/01/2021.
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Hipotermia , Tato , Adulto , Humanos , Temperatura , Temperatura Corporal , Anestesia GeralRESUMO
Endothelin-1 (ET-1) is a member of the endothelin family of peptide hormones first discovered as endothelium-derived mediators regulating vascular tone. ET-1 also regulates the proliferation and differentiation of bone cells that synthesize fibroblast growth factor 23 (FGF23). FGF23 is a hormone controlling renal phosphate and vitamin D metabolism. Here, we studied the role of ET-1 and endothelin receptor B (ETB) for FGF23 production. Fgf23 gene expression was studied in IDG-SW3 bone cells by quantitative RT-PCR. ETB-expressing (etb+/+ ) and rescued ETB-deficient mice (etb-/- ) were studied in metabolic cages. Their serum FGF23, PTH, and 1,25(OH)2 D3 concentrations were determined by ELISA, serum and urinary phosphate and Ca2+ by photometric methods. ET-1 and ETB agonist sarafotoxin 6c suppressed Fgf23 mRNA in IDG-SW3 cells. Serum C-terminal and intact FGF23 as well as bone Fgf23 mRNA levels were significantly higher in etb-/- mice than in etb+/+ mice. Renal phosphate excretion was significantly higher in etb-/- mice despite lower phosphate levels. In addition, etb-/- animals exhibited calciuria and a significantly higher serum 1,25(OH)2 D3 concentration compared to etb+/+ mice. In conclusion, ETB-dependent ET-1 signaling is a potent suppressor of FGF23 formation. This effect is likely to be of clinical relevance given the use of endothelin receptor antagonists in various diseases.
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Fatores de Crescimento de Fibroblastos/metabolismo , Regulação da Expressão Gênica , Receptor de Endotelina B/fisiologia , Animais , Osso e Ossos/metabolismo , Cálcio/metabolismo , Feminino , Fator de Crescimento de Fibroblastos 23 , Fatores de Crescimento de Fibroblastos/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfatos/metabolismoRESUMO
Polyelectrolyte multilayers (PEMs) consisting of the polysaccharides hyaluronic acid (HA) as the polyanion and chitosan (Chi) as the polycation were prepared with layer-by-layer technique (LbL). The [Chi/HA]5 multilayers were exposed to solutions of metal ions (Ca2+, Co2+, Cu2+ and Fe3+). Binding of metal ions to [Chi/HA]5 multilayers by the formation of complexes with functional groups of polysaccharides modulates their physical properties and the bioactivity of PEMs with regard to the adhesion and function of multipotent murine C3H10T1/2 embryonic fibroblasts. Characterization of multilayer formation and surface properties using different analytical methods demonstrates changes in the wetting, surface potential and mechanical properties of multilayers depending on the concentration and type of metal ion. Most interestingly, it is observed that Fe3+ metal ions greatly promote adhesion and spreading of C3H10T1/2 cells on the low adhesive [Chi/HA]5 PEM system. The application of intermediate concentrations of Cu2+, Ca2+ and Co2+ as well as low concentrations of Fe3+ to PEMs also results in increased cell spreading. Moreover, it can be shown that complex formation of PEMs with Cu2+ and Fe3+ ions leads to increased metabolic activity in cells after 24 h and induces cell differentiation towards adipocytes in the absence of any additional adipogenic media supplements. Overall, complex formation of [Chi/HA]5 PEM with metal ions like Cu2+ and Fe3+ represents an interesting and cheap alternative to the use of growth factors for making cell-adhesive coatings and guiding stem cell differentiation on implants and scaffolds to regenerate connective-type of tissues.
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Quitosana , Ácido Hialurônico , Animais , Adesão Celular , Diferenciação Celular , Fibroblastos , Íons , Camundongos , Propriedades de SuperfícieRESUMO
BACKGROUND: Prevention of inadvertent hypothermia is recommended for procedures >30 minutes because hypothermia increases the risk of myocardial ischemia, intraoperative blood loss, transfusion and wound complications. Therefore, short warming interruptions between pre-warming and intraoperative warming might result in lower hypothermia rates. The aim of this retrospective investigation was to determine whether the incidence of inadvertent intraoperative hypothermia was affected by the warming interruption. METHODS: The lowest intraoperative body core temperature value and the warming interruption time were taken from anaesthesia records. Body core temperature was recorded continuously, and a patient was classified to be hypothermic if the lowest recorded temperature value was <36°C. Hypothermia rates and the correlation between warming interruption times and intraoperative hypothermia rates were calculated. RESULTS: Five thousand eighty-four patients were analysed. The intraoperative hypothermia rate was 15.3%. Nineteen patients (0.4%) had a recorded temperature of <35.0°C. An increase in forced-air warming interruption time was significantly associated with an increase in intraoperative hypothermia rates (P < .0001). Patients with interruptions in forced-air warming >20 minutes showed significantly higher hypothermia rates than those with interruptions of ≤20 minutes (P < .0001). CONCLUSION: Intraoperative hypothermia rates increased significantly with longer forced-air warming interruptions between pre-warming and intraoperative warming. Short warming interruptions can preserve the effect of pre-warming and are associated with low intraoperative hypothermia rates.
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Hipotermia/prevenção & controle , Cuidados Intraoperatórios/métodos , Complicações Intraoperatórias/prevenção & controle , Reaquecimento/métodos , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , TempoRESUMO
To avoid pathogen-associated molecular pattern recognition, the hemibiotrophic maize pathogen Colletotrichum graminicola secretes proteins mediating the establishment of biotrophy. Targeted deletion of 26 individual candidate genes and seven gene clusters comprising 32 genes of C. graminicola identified a pathogenicity cluster (CLU5) of five co-linear genes, all of which, with the exception of CLU5b, encode secreted proteins. Targeted deletion of all genes of CLU5 revealed that CLU5a and CLU5d are required for full appressorial penetration competence, with virulence deficiencies independent of the host genotype and organ inoculated. Cytorrhysis experiments and microscopy showed that Δclu5a mutants form pressurized appressoria, but they are hampered in forming penetration pores and fail to differentiate a penetration peg. Whereas Δclu5d mutants elicited WT-like papillae, albeit at increased frequencies, papillae induced by Δclu5a mutants were much smaller than those elicited by the WT. Synteny of CLU5 is not only conserved in Colletotrichum spp. but also in additional species of Sordariomycetes including insect pathogens and saprophytes suggesting importance of CLU5 for fungal biology. Since CLU5a and CLU5d also occur in non-pathogenic fungi and since they are expressed prior to plant invasion and even in vegetative hyphae, the encoded proteins probably do not act primarily as effectors.
Assuntos
Colletotrichum/metabolismo , Proteínas Fúngicas/metabolismo , Doenças das Plantas/microbiologia , Zea mays/microbiologia , Colletotrichum/genética , Colletotrichum/patogenicidade , Proteínas Fúngicas/genética , Hifas/genética , Hifas/metabolismo , Hifas/patogenicidade , Família Multigênica , Deleção de Sequência , VirulênciaRESUMO
OBJECTIVES: Collagen membranes are not limited to be occlusive barriers as they actively support bone regeneration. However, the impact of bone-derived growth factors on their osteoconductive competence has not been examined. METHODS: Twenty adult Sprague Dawley rats were included in the study. Calvaria defects with a diameter of five millimeter were created. The defect was covered with one layer of a collagen membrane previously soaked in conditioned medium of porcine bone chips or in culture medium alone. After 4 weeks, microcomputed tomography was performed. Undecalcified thin-ground sections were subjected to light and scanning electron microscopy. Primary outcome parameter was the bone volume in the defect. Unit of analysis was the bone-conditioned medium (BCM). RESULTS: In the central defect area of the control and the BCM group, median new bone connected to the host bone was 0.54 and 0.32 mm³, respectively (p = .10). In the ectocranial defect area, the control group showed significantly more bone than the BCM group (0.90 and 0.26 mm³; p = .02). Based on an exploratory interpretation, the control group had smaller bony islands than the BCM group. Scanning electron microscopy and histology indicate the formation of bone but also the collagen membrane to be mineralized in the defect site. CONCLUSIONS: These results demonstrate that the commercial collagen membrane holds an osteoconductive competence in a rat calvaria defect model. Soaking collagen membranes with BCM shifts bone formation toward the formation of bony islands rather than new bone connected to the host bone.
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Regeneração Óssea , Colágeno , Membranas Artificiais , Crânio/anatomia & histologia , Crânio/cirurgia , Animais , Meios de Cultivo Condicionados , Feminino , Ratos , Ratos Sprague-DawleyRESUMO
The stability of strong polyelectrolyte brushes (PEBs) was studied in bulk and in patterned structures. Thick PEBs of poly([(2-methacryloyloxy)ethyl]trimethylammonium chloride) with thicknesses >100 nm were synthesized using single electron transfer living radical polymerization. Brush patterning was identified using deep-ultraviolet photolithography by means of either a top-down (TD) or bottom-up (BU) method, with features as small as 200 nm. The brushes were soaked in water under a range of pH or temperature conditions, and the hydrolysis was monitored through dry-state ellipsometry and atomic force microscopy measurements. BU patterns showed reduced degrafting for smaller patterns, which was attributed to increased stress relaxation at such dimensions. In contrast to the already relaxed BU-patterned brush, a TD-patterned brush possesses perpendicular structures that result from the use of orthogonal lithography. It was found that the TD process induces cross-linking on the sidewall, which subsequently fortifies the sidewall materials. This modification of the polymer brushes hindered the stress relaxation of the patterns, and the degrafting trends became irrelevant to the pattern sizes. With proper tuning, the cross-linking on the sidewall was minimized and the degrafting trends were again relaxation-dependent.
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Spin-resolved scanning tunneling microscopy is used to reveal a commensurate hexagonal nanoskyrmion lattice in the hcp stacked Fe monolayer on Ir(111). The exact nature of the spin configuration is due to magnetic interactions between the Fe atoms and the Ir substrate, either originating from polarization effects, or due to a three-site hopping mechanism of the Dzyaloshinsky-Moriya interaction leading to a canting of the Dzyaloshinsky-Moriya vector with respect to the interface.
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BACKGROUND: Spider silk is a tear-resistant and elastic biopolymer that has outstanding mechanical properties. Additionally, exiguous immunogenicity is anticipated for spider silks. Therefore, spider silk represents a potential ideal biomaterial for medical applications. All known spider silk proteins, so-called spidroins, reveal a composite nature of silk-specific units, allowing the recombinant production of individual and combined segments. RESULTS: In this report, a miniaturized spidroin gene, named VSO1 that contains repetitive motifs of MaSp1 has been synthesized and combined to form multimers of distinct lengths, which were heterologously expressed as elastin-like peptide (ELP) fusion proteins in tobacco. The elastic penetration moduli of layered proteins were analyzed for different spidroin-based biopolymers. Moreover, we present the first immunological analysis of synthetic spidroin-based biopolymers. Characterization of the binding behavior of the sera after immunization by competitive ELISA suggested that the humoral immune response is mainly directed against the fusion partner ELP. In addition, cytocompatibility studies with murine embryonic fibroblasts indicated that recombinant spidroin-based biopolymers, in solution or as coated proteins, are well tolerated. CONCLUSION: The results show that spidroin-based biopolymers can induce humoral immune responses that are dependent on the fusion partner and the overall protein structure. Furthermore, cytocompatibility assays gave no indication of spidroin-derived cytotoxicity, suggesting that recombinant produced biopolymers composed of spider silk-like repetitive elements are suitable for biomedical applications.
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Fibroínas/biossíntese , Fibroínas/imunologia , Nicotiana/crescimento & desenvolvimento , Aranhas/genética , Animais , Biopolímeros/biossíntese , Biopolímeros/química , Biopolímeros/genética , Biopolímeros/imunologia , Fibroínas/química , Fibroínas/genética , Camundongos , Peptídeos/imunologia , Plantas Geneticamente Modificadas , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Seda , Aranhas/química , Nicotiana/genética , Nicotiana/metabolismoRESUMO
The ascomycete and causative agent of maize anthracnose and stem rot, Colletotrichum graminicola, differentiates melanized infection cells called appressoria that are indispensable for breaching the plant cell wall. High concentrations of osmolytes accumulate within the appressorium, and the internal turgor pressure of up to 5.4 MPa provides sufficient force to penetrate the leaf epidermis directly. In order to assess the function of melanin in C. graminicola appressoria, we identified and characterized the polyketide synthase 1 (CgPKS1) gene which displayed high similarity to fungal polyketide synthases (PKS) involved in synthesis of 1,3,6,8-tetrahydronaphthalene, the first intermediate in melanin biosynthesis. Cgpks1 albino mutants created by targeted gene disruption were unable to penetrate intact leaves and ruptured frequently but, surprisingly, were able to penetrate ultrathin polytetrafluoroethylene membranes mimicking the plant surface. Nonmelanized Cgpks1 appressoria were sensitive to externally applied cell-wall-degrading enzymes whereas melanized appressoria were not affected. Expression studies using a truncated CgPKS1 fused to green fluorescent protein revealed fluorescence in immature appressoria and in setae, which is in agreement with transcript data obtained by RNA-Seq and quantitative polymerase chain reaction. Unexpectedly, surface scans of mutant and wild-type appressoria revealed considerable differences in cell-wall morphology. Melanization of appressoria is indispensable for successful infection of intact leaves. However, cell collapse experiments and analysis of the appressorial osmolyte content by Mach-Zehnder interferometry convincingly showed that melanin is not required for solute accumulation and turgor generation, thus questioning the role of melanin as a barrier for osmolytes in appressoria of C. graminicola.
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Parede Celular/fisiologia , Colletotrichum/fisiologia , Melaninas/biossíntese , Zea mays/microbiologia , DNA Fúngico/genética , Regulação Fúngica da Expressão Gênica/fisiologia , Melaninas/genética , Microscopia de Força Atômica , Dados de Sequência Molecular , Doenças das Plantas/microbiologiaRESUMO
In the last two decades it was shown that plants have a great potential for production of specific heterologous proteins. But high cost and inefficient downstream processing are a main technical bottleneck for the broader use of plant-based production technology especially for protein-based products, for technical use as fibres or biodegradable plastics and also for medical applications. High-performance fibres from recombinant spider silks are, therefore, a prominent example. Spiders developed rather different silk materials that are based on proteins. These spider silks show excellent properties in terms of elasticity and toughness. Natural spider silk proteins have a very high molecular weight, and it is precisely this property which is thought to give them their strength. Transgenic plants were generated to produce ELPylated recombinant spider silk derivatives. These fusion proteins were purified by Inverse Transition Cycling (ITC) and enzymatically multimerized with transglutaminase in vitro. Layers produced by casting monomers and multimers were characterized using atomic force microscopy (AFM) and AFM-based nanoindentation. The layered multimers formed by mixing lysine- and glutamine-tagged monomers were associated with the highest elastic penetration modulus.
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Fibroínas/biossíntese , Nicotiana/metabolismo , Seda/biossíntese , Aranhas/metabolismo , Transglutaminases/metabolismo , Animais , Fibroínas/química , Fibroínas/isolamento & purificação , Microscopia de Força Atômica , Agricultura Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Multimerização Proteica , Proteínas Recombinantes de Fusão , Seda/isolamento & purificação , Nicotiana/genética , Transglutaminases/genéticaRESUMO
The magnetic ground state of biatomic Fe chains on the reconstructed (5×1)-Ir(001) surface is a cycloidal 120° spin spiral. Spin-resolved scanning tunneling microscopy reveals a striking variation of magnetic field dependences among the chains, which we attribute to parity effects resulting from finite lengths. Numerical simulations show that the chains are divided in three symmetry classes with the exact number of atoms in the chain determining the size and direction of their net magnetic moment. In contrast to antiferromagnetic systems, the three-atom periodicity causes the effective anisotropy to alternate between out of plane, in plane, and quenched.
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BACKGROUND AND AIMS: Forisomes are specialized structural phloem proteins that mediate sieve element occlusion after wounding exclusively in papilionoid legumes, but most studies of forisome structure and function have focused on the Old World clade rather than the early lineages. A comprehensive phylogenetic, molecular, structural and functional analysis of forisomes from species covering a broad spectrum of the papilionoid legumes was therefore carried out, including the first analysis of Dipteryx panamensis forisomes, representing the earliest branch of the Papilionoideae lineage. The aim was to study the molecular, structural and functional conservation among forisomes from different tribes and to establish the roles of individual forisome subunits. METHODS: Sequence analysis and bioinformatics were combined with structural and functional analysis of native forisomes and artificial forisome-like protein bodies, the latter produced by expressing forisome genes from different legumes in a heterologous background. The structure of these bodies was analysed using a combination of confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the function of individual subunits was examined by combinatorial expression, micromanipulation and light microscopy. KEY RESULTS: Dipteryx panamensis native forisomes and homomeric protein bodies assembled from the single sieve element occlusion by forisome (SEO-F) subunit identified in this species were structurally and functionally similar to forisomes from the Old World clade. In contrast, homomeric protein bodies assembled from individual SEO-F subunits from Old World species yielded artificial forisomes differing in proportion to their native counterparts, suggesting that multiple SEO-F proteins are required for forisome assembly in these plants. Structural differences between Medicago truncatula native forisomes, homomeric protein bodies and heteromeric bodies containing all possible subunit combinations suggested that combinations of SEO-F proteins may fine-tune the geometric proportions and reactivity of forisomes. CONCLUSIONS: It is concluded that forisome structure and function have been strongly conserved during evolution and that species-dependent subsets of SEO-F proteins may have evolved to fine-tune the structure of native forisomes.
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Fabaceae/genética , Proteínas de Plantas/genética , Proteínas de Plantas/ultraestrutura , Sequência de Aminoácidos , Biologia Computacional , Fabaceae/química , Fabaceae/metabolismo , Microscopia Confocal , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas/metabolismo , Alinhamento de SequênciaAssuntos
Temperatura Corporal , Temperatura Alta , Craniotomia , Humanos , Temperatura Cutânea , TemperaturaRESUMO
Phytophenols are considered to have beneficial effects towards human physiology. They are food microcomponents with potent chemopreventive properties towards the most three frequent contemporary human diseases, e.g., cardiovascular alterations, cancer and neurodegenerative pathologies. Related to this, the plasmatic form and plasmatic level of plant polyphenols in the body circulation are crucial for their efficiency. Thus, determinations of the binding process of resveratrol and of common flavonoids produced by major edible plants, berries and fruits to plasma proteins are essential. The interactions between resveratrol and albumin, a major plasma protein, were compared with those already published, involving curcumin, genistein, quercetin and other well-known food-containing polyphenols. The approaches used are usually intrinsic fluorescence intensity changes, quenching of protein intrinsic fluorescence and infrared spectroscopy. It appears that: (1) all of the studied polyphenols interact with albumin; (2) while most of the studied polyphenols interact at one albumin binding site, there are two different types of resveratrol binding sites for bovine serum albumin, one with the highest affinity (apparent KD of 4 µM) with a stoichiometry of one per monomer and a second with a lower affinity (apparent KD of 20 µM) with also a stoichiometry of one per monomer; (3) at least one binding site is in the vicinity of one tryptophanyl residue of bovine serum albumin; and (4) resveratrol binding to bovine serum albumin produces a very small structural conformation change of the polypeptide chain. These results support a role played by polyphenols-albumin interactions in the plasma for the bio-activities of these food microcomponents in the body.
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Sítios de Ligação/fisiologia , Plantas Comestíveis/metabolismo , Polifenóis/metabolismo , Albumina Sérica/metabolismo , Estilbenos/metabolismo , Dieta/métodos , Flavonoides/metabolismo , Alimentos , Saúde , Humanos , ResveratrolRESUMO
The synthesis of native-sized proteins is a pre-requisite for exploiting the potential of spider silk as a bio-based material. The unique properties of spider silk, such as extraordinary tensile strength and elasticity, result from the highly repetitive nature of spider silk protein motifs. The present report describes the combination of spider silk flagelliform protein (FLAG) production in the endoplasmic reticulum of tobacco plant leaf cells with an intein-based posttranslational protein fusion technology. The repeated ligation of FLAG monomers resulted in the formation of large multimers. This method avoids the need for highly repetitive transgenes, which may result in a higher genetic and transcriptional stability. Here we show, for the first time, the production of synthetic, high molecular weight spider silk proteins larger than 250 kDa based on the assembly of protein monomers via intein-mediated trans-splicing in planta. The resulting multimeric structures form microfibers, thereby demonstrating their great potential as a biomaterial.
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Proteínas de Artrópodes/genética , Inteínas/genética , Nicotiana/genética , Plantas Geneticamente Modificadas , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/biossíntese , Regulação da Expressão Gênica de Plantas , Proteínas de Insetos , Multimerização Proteica , Seda/genética , Aranhas/química , Aranhas/genética , Trans-Splicing/genéticaRESUMO
Dentin hypersensitivity is an oral health concern affecting a large percentage of the world's adult population. Occlusion of the exposed dentinal tubules is among the treatment options available, and silver diammine fluoride (SDF) is an occluding agent used for interrupting or dampening the stimulus of the dental pulp nerves that produce pain. In addition to dentin permeability testing, the evaluation of desensitizing agents occluding dentinal tubules strongly relies on microscopic techniques, such as scanning electron microscopy (SEM). Limitations of SEM are that it provides only surface images that lack detailed information on the depth of penetration and amount of material present within the treated specimen, and it is prone to sample preparation artifacts. Here, we present high-resolution X-ray computed tomography (nano-CT) as a potential method for investigating dentin specimens with occluded tubules. We studied human dentin treated with SDF as an exemplary dentinal occlusion treatment option. We evaluated the silver deposits formed on the dentin surface region near the dentinal tubules and in the tubular regions using cross-section SEM, Energy Dispersive X-ray (EDX) analysis, and nano-CT. The resulting images obtained by SEM and nano-CT had comparable resolutions, and both techniques produced images of the tubules' occlusion. Nano-CT provided three-dimensional images adequate to quantitate tubule size and orientation in space. Moreover, it enabled clear visualization of dentinal tubules in any virtual plane and estimation of the amount and depth of occluding material. Thus, nano-CT has the potential to be a valuable technique for evaluating the occluding effects of virtually any material applied to dentinal tubules, supporting deciding between the best occluding treatment options.
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Artefatos , Tomografia Computadorizada por Raios X , Adulto , Humanos , Microscopia Eletrônica de Varredura , Dentina/diagnóstico por imagemRESUMO
Elastin is an essential extracellular matrix protein that enables tissues and organs such as arteries, lungs, and skin, which undergo continuous deformation, to stretch and recoil. Here, an approach to fabricating artificial elastin with close-to-native molecular and mechanical characteristics is described. Recombinantly produced tropoelastin are polymerized through coacervation and allysine-mediated cross-linking induced by pyrroloquinoline quinone (PQQ). A technique that allows the recovery and repeated use of PQQ for protein cross-linking by covalent attachment to magnetic Sepharose beads is developed. The produced material closely resembles natural elastin in its molecular, biochemical, and mechanical properties, enabled by the occurrence of the cross-linking amino acids desmosine, isodesmosine, and merodesmosine. It possesses elevated resistance against tryptic proteolysis, and its Young's modulus ranging between 1 and 2 MPa is similar to that of natural elastin. The approach described herein enables the engineering of mechanically resilient, elastin-like materials for biomedical applications.
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Elastina , Tropoelastina , Elastina/química , Tropoelastina/química , Aminoácidos , ProteóliseRESUMO
Delivery of growth factors (GFs) is challenging for regulation of cell proliferation and differentiation due to their rapid inactivation under physiological conditions. Here, a bioactive polyelectrolyte multilayer (PEM) is engineered by the combination of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and glycosaminoglycans to be used as reservoir for GF storage. PNIPAM-grafted-chitosan (PChi) with two degrees of substitution (DS) are synthesized, namely LMW* (DS 0.14) and HMW (DS 0.03), by grafting low (2 kDa) and high (10 kDa) molecular weight of PNIPAM on the backbone of chitosan (Chi) to be employed as polycations to form PEM with the polyanion heparin (Hep) at pH 4. Subsequently, PEMs are chemically crosslinked to improve their stability at physiological pH 7.4. Resulting surface and mechanical properties indicate that PEM containing HMW is responsive to temperature at 20 °C and 37 °C, while LMW is not. More importantly, Hep as terminal layer combined with HMW allows not only a better retention of the adhesive protein vitronectin but also a sustained release of FGF-2 at 37 °C. With the synergistic effect of vitronectin and matrix-bound FGF-2, significant promotion on adhesion, proliferation, and migration of 3T3 mouse embryonic fibroblasts is achieved on HMW-containing PEM compared to Chi-containing PEM and exogenously added FGF-2. Thus, PEM containing PNIPAM in combination with bioactive glycosaminoglycans like Hep represents a versatile approach to fabricate a GF delivery system for efficient cell culture, which can be potentially served as cell culture substrate for production of (stem) cells and bioactive wound dressing for tissue regeneration.
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Quitosana , Heparina , Animais , Camundongos , Heparina/farmacologia , Heparina/química , Quitosana/química , Quitosana/farmacologia , Fator 2 de Crescimento de Fibroblastos/farmacologia , Vitronectina/farmacologia , Adesão Celular , Fibroblastos , Glicosaminoglicanos/química , Glicosaminoglicanos/farmacologiaRESUMO
A gene-activated surface coating is presented as a strategy to design smart biomaterials for bone tissue engineering. The thin-film coating is based on polyelectrolyte multilayers composed of collagen I and chondroitin sulfate, two main biopolymers of the bone extracellular matrix, which are fabricated by layer-by-layer assembly. For further functionalization, DNA/lipid-nanoparticles (lipoplexes) are incorporated into the multilayers. The polyelectrolyte multilayer fabrication and lipoplex deposition are analyzed by surface sensitive analytical methods that demonstrate successful thin-film formation, fibrillar structuring of collagen, and homogenous embedding of lipoplexes. Culture of mesenchymal stem cells on the lipoplex functionalized multilayer results in excellent attachment and growth of them, and also, their ability to take up cargo like fluorescence-labelled DNA from lipoplexes. The functionalization of the multilayer with lipoplexes encapsulating DNA encoding for transient expression of bone morphogenetic protein 2 induces osteogenic differentiation of mesenchymal stem cells, which is shown by mRNA quantification for osteogenic genes and histochemical staining. In summary, the novel gene-functionalized and extracellular matrix mimicking multilayer composed of collagen I, chondroitin sulfate, and lipoplexes, represents a smart surface functionalization that holds great promise for tissue engineering constructs and implant coatings to promote regeneration of bone and other tissues.