RESUMO
OBJECTIVE: Orthosiphon stamineus (OS) or Misai Kucing (Java tea) is a popular herbal supplement from Southeast Asia for various metabolic, age-related diseases. This study investigated the potential use of OS leaf extracts to ameliorate osteoporosis in ovariectomized rats. METHODS: Fifty-six female Sprague-Dawley rats were randomly allocated into eight groups (nâ=â7): SHAM (healthy sham control); OVX (ovarietomized) nontreated rats (negative control); OVXâ+âRemifemin (100âmg/kg body weight), and 2% green tea extract (positive controls); OVXâ+âOS 50% ethanolic and aqueous extracts, both at either 150 or 300âmg/kg. After 16 weeks, the rats' bones and blood were evaluated for osteoporosis indicators (protein and mRNA expressions), micro-computed tomography for bone histomorphometry, and three-point bending test for tibia mechanical strength. RESULTS: The extracts dose-dependently and significantly (Pâ<â0.05) improved bone strength and flexibility, bone mineral density, bone formation protein markers (P1NP), and bone histomorphometry. All extracts reduced the inflammation biomarker (interleukin-6). The extracts up-regulated osteoblastogenesis (bone morphogenetic protein-2) and collagen-1 synthesis (collagen type 1 alpha-1) mRNA expressions, and down-regulated bone resorption (TNFSF11 and nuclear factor-kappa B) mRNA expressions. Both the water and 50% ethanolic extract were effective. The effective dose is equivalent to 25 to 50âmg/kg extract for humans. CONCLUSIONS: The extract showed bone-protective and antiosteoporotic effects (improving bone strength, flexibility, bone density, and bone morphometry) by reducing inflammation and the bone resorption biomarkers, while enhancing bone formation biomarkers and collagen synthesis.
Assuntos
Orthosiphon , Osteoporose Pós-Menopausa/prevenção & controle , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Chás de Ervas , Animais , Densidade Óssea/efeitos dos fármacos , Proteína Morfogenética Óssea 2/genética , Reabsorção Óssea/genética , Osso e Ossos/fisiopatologia , Colágeno Tipo I/genética , Cadeia alfa 1 do Colágeno Tipo I , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/sangue , Interleucina-6/sangue , NF-kappa B/genética , Osteoporose Pós-Menopausa/diagnóstico por imagem , Osteoporose Pós-Menopausa/metabolismo , Osteoporose Pós-Menopausa/patologia , Osteoprotegerina/sangue , Ovariectomia , Fragmentos de Peptídeos/sangue , Folhas de Planta , Maleabilidade/efeitos dos fármacos , Pró-Colágeno/sangue , Ligante RANK/metabolismo , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Microtomografia por Raio-XRESUMO
Two-dimensional (2D) crystalline materials possess unique structural, mechanical and electronic properties that make them highly attractive in many applications. Although there have been advances in preparing 2D materials that consist of one or a few atomic or molecular layers, bottom-up assembly of 2D crystalline materials remains a challenge and an active area of development. More challenging is the design of dynamic 2D lattices that can undergo large-scale motions without loss of crystallinity. Dynamic behaviour in porous three-dimensional (3D) crystalline solids has been exploited for stimuli-responsive functions and adaptive behaviour. As in such 3D materials, integrating flexibility and adaptiveness into crystalline 2D lattices would greatly broaden the functional scope of 2D materials. Here we report the self-assembly of unsupported, 2D protein lattices with precise spatial arrangements and patterns using a readily accessible design strategy. Three single- or double-point mutants of the C4-symmetric protein RhuA were designed to assemble via different modes of intermolecular interactions (single-disulfide, double-disulfide and metal-coordination) into crystalline 2D arrays. Owing to the flexibility of the single-disulfide interactions, the lattices of one of the variants ((C98)RhuA) are essentially defect-free and undergo substantial, but fully correlated, changes in molecular arrangement, yielding coherently dynamic 2D molecular lattices. (C98)RhuA lattices display a Poisson's ratio of -1-the lowest thermodynamically possible value for an isotropic material-making them auxetic.
Assuntos
Aldeído Liases/química , Aldeído Liases/metabolismo , Maleabilidade , Aldeído Liases/genética , Aldeído Liases/ultraestrutura , Cristalização , Dissulfetos/química , Dissulfetos/metabolismo , Escherichia coli/química , Metais/química , Metais/farmacologia , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteínas Mutantes/ultraestrutura , Maleabilidade/efeitos dos fármacos , Conformação Proteica/efeitos dos fármacos , Rotação , Estresse Mecânico , TermodinâmicaRESUMO
This study evaluated the effects of etching with increasing hydrofluoric (HF) acid concentrations on the roughness and flexural strength of a feldspathic ceramic. One hundred and fifty ceramic specimens (14×4×1.2 mm(2)) were produced from ceramic blocks (VitaBlocks Mark II). All specimens were polished, chamfered and sonically cleaned in isopropyl alcohol. Specimens were randomly divided into 5 groups (n=30): SC (control) no ceramic surface etching; HF1, HF3, HF5 and HF10 ceramic surface etching for 60s with 1%, 3%, 5% and 10% HF acid concentrations, respectively. Profilometry was performed in all specimens to evaluate roughness prior to flexural strength testing. Data were analyzed using one-way ANOVA and Tukey׳s test (α=0.05). Weibull module (m) and characteristic stress (σc) were also determined. HF acid etching, regardless of the concentration used, led to significantly rougher surfaces than the control (p<0.05). However, the mean flexural strength values were not statistically different among the etched groups (106.47 to 102.02 MPa). Acid etching significantly reduced the mean flexural strength when compared with the control (143.3 MPa). Weibull modulus of the groups was similar, except for the HF5 group that was higher compared to HF3. Flexural strength was similarly affected by the different HF acid concentrations tested, but roughness increased higher the acid concentration. Ceramic etching led to a significant reduction in strength when compared to the untreated ceramic, regardless of its concentration.
Assuntos
Cerâmica , Porcelana Dentária , Ácido Fluorídrico/administração & dosagem , Análise do Estresse Dentário , Teste de Materiais , Maleabilidade/efeitos dos fármacos , Estresse Mecânico , Propriedades de Superfície/efeitos dos fármacosRESUMO
There is now a certain consensus that transcription factors (TFs) reach their target sites, where they regulate gene transcription, via a mechanism dubbed facilitated diffusion (FD). In FD, the TF cycles between events of 3D diffusion in solution (jumps), 1D diffusion along DNA (sliding), and small jumps (hopping), achieving association rates higher than for 3D diffusion alone. We investigate the FD phenomenology through molecular dynamics simulations in the framework of coarse-grained modeling. We show that, despite the crude approximations, the model generates, upon varying the equilibrium distance of the DNA-TF interaction, a phenomenology matching a number of experimental and numerical results obtained with more refined models. In particular, focusing on the kinematics of the process, we characterize the geometrical properties of TF trajectories during sliding. We find that sliding occurs via helical paths around the DNA helix, leading to a coupling of translation along the DNA axis with rotation around it. The 1D diffusion constant measured in simulations is found to be interwoven with the geometrical properties of sliding and we develop a simple argument that can be used to quantitatively reproduce the measured values.
Assuntos
DNA/química , Simulação de Dinâmica Molecular , Fatores de Transcrição/química , Difusão/efeitos dos fármacos , Maleabilidade/efeitos dos fármacos , Cloreto de Sódio/farmacologiaRESUMO
We study the effects of cisplatin on the circular configuration of DNA using atomic force microscopy (AFM) and observe that the DNA gradually transforms to a complex configuration with an intersection and interwound structures from a circlelike structure. An algorithm is developed to extract the configuration profiles of circular DNA from AFM images and the radius of gyration is used to describe the flexibility of circular DNA. The quantitative analysis of the circular DNA demonstrates that the radius of gyration gradually decreases and two processes on the change of flexibility of circular DNA are found as the cisplatin concentration increases. Furthermore, a model is proposed and discussed to explain the mechanism for understanding the complicated interaction between DNA and cisplatin.
Assuntos
Antineoplásicos/farmacologia , Cisplatino/farmacologia , DNA Circular/química , Conformação de Ácido Nucleico/efeitos dos fármacos , DNA Circular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Maleabilidade/efeitos dos fármacosRESUMO
INTRODUCTION: Human placental stem villi (PSV) present contractile properties. We studied the role of actin-myosin cross bridges (CBs) and the effects of NO-cGMP pathway modulators in the PSV contraction and relaxation. METHODS: In vitro contractile properties were investigated in 71 PSV from term human placentas studied according to their long axis. Contraction was induced by both KCl and electrical tetanic stimulation. Relaxation was induced by inhibiting the CB cycle with either 2,3-butanedione monoxime (BDM) or blebbistatin (BLE) and by activating the NO-cGMP pathway with isosorbide dinitrate (ISDN), sildenafil (SIL) or ISDN + SIL. RESULTS: PSV tension slowly increased by 140% of the basal tone after KCl exposure and by 85% after tetanus. The addition of BDM, BLE, ISDN, SIL and ISDN + SIL induced a relaxation of PSV, the overall time course of relaxation (in s) was respectively (means ± SD) 3412 ± 1904, 14,250 ± 3095*, 3813 ± 1383, 2883 ± 1188 and 2440 ± 477; significantly longer in BLE compared with BDM, ISDN, SIL and ISDN + SIL:*p < 0.001). the overall time course of relaxation (in s) was respectively (means ± SD) 3412 ± 1904, 14,250 ± 3095*, 3813 ± 1383, 2883 ± 1188 and 2440 ± 477; significantly longer in BLE compared with BDM, ISDN, SIL and ISDN + SIL:*p < 0.001). These relaxation kinetics were particularly slow. Other relaxation parametres, i.e., maximum lengthening, -peak dT/dt, and resting tension, did not differ between these 5 subgroups. DISCUSSION AND CONCLUSION: Isolated human PSV were able to contract after both KCl exposure and tetanus. This increase in contractility was reversed by inhibiting the CB cycle with BDM or BLE and by stimulating the NO-cGMP pathway with ISDN or SIL. The association ISDN + SIL did not potentiate the relaxing processes.
Assuntos
Actinas/fisiologia , Vilosidades Coriônicas/fisiologia , GMP Cíclico/fisiologia , Miosinas/fisiologia , Óxido Nítrico/fisiologia , Sistemas do Segundo Mensageiro , Actinas/antagonistas & inibidores , Actinas/química , Vilosidades Coriônicas/química , Vilosidades Coriônicas/efeitos dos fármacos , GMP Cíclico/agonistas , GMP Cíclico/antagonistas & inibidores , Diacetil/análogos & derivados , Diacetil/farmacologia , Estimulação Elétrica , Inibidores Enzimáticos/farmacologia , Feminino , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Técnicas In Vitro , Dinitrato de Isossorbida/farmacologia , Cinética , Miosinas/antagonistas & inibidores , Miosinas/química , Óxido Nítrico/agonistas , Óxido Nítrico/antagonistas & inibidores , Doadores de Óxido Nítrico/farmacologia , Piperazinas/farmacologia , Maleabilidade/efeitos dos fármacos , Cloreto de Potássio/metabolismo , Gravidez , Estrutura Quaternária de Proteína , Purinas/farmacologia , Sistemas do Segundo Mensageiro/efeitos dos fármacos , Citrato de Sildenafila , Sulfonas/farmacologia , Nascimento a TermoRESUMO
The objective of this study was to evaluate the influence of different surface agents on the flexural strength of a ceramic system. Eighty bar-shaped specimens of zirconia were divided into four groups according to the agent to be used: group Control--to be cleaned with alcohol; group VM9--application of a fluid layer of porcelain; group Effect Bonder--application of a bonding agent; and group Coloring Liquid--application of coloring liquid. All specimens received the porcelain application by the layering technique and were then subjected to thermocycling. The four-point bending test was performed to calculate the strength values (σ, MPa) and the failure modes were classified. ANOVA did not detect significant differences among the groups. The Weibull modulus were 5 (Control, VM9 and Effect Bonder) and 6 (Coloring Liquid). The cracking of the porcelain ceramic toward the interface was the predominant failure mode. It was concluded that the surface agents tested had no effect on the flexural strength of the bilaminated ceramic specimens.
Assuntos
Cerâmica/química , Facetas Dentárias , Ítrio/química , Zircônio/química , Análise de Variância , Materiais Dentários/química , Falha de Restauração Dentária , Temperatura Alta , Teste de Materiais , Maleabilidade/efeitos dos fármacos , Estresse Mecânico , Propriedades de Superfície/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos , Fatores de TempoRESUMO
The objective of this study was to evaluate the influence of different surface agents on the flexural strength of a ceramic system. Eighty bar-shaped specimens of zirconia were divided into four groups according to the agent to be used: group Control - to be cleaned with alcohol; group VM9 - application of a fluid layer of porcelain; group Effect Bonder - application of a bonding agent; and group Coloring Liquid - application of coloring liquid. All specimens received the porcelain application by the layering technique and were then subjected to thermocycling. The four-point bending test was performed to calculate the strength values (σ, MPa) and the failure modes were classified. ANOVA did not detect significant differences among the groups. The Weibull modulus were 5 (Control, VM9 and Effect Bonder) and 6 (Coloring Liquid). The cracking of the porcelain ceramic toward the interface was the predominant failure mode. It was concluded that the surface agents tested had no effect on the flexural strength of the bilaminated ceramic specimens.
Assuntos
Cerâmica/química , Facetas Dentárias , Ítrio/química , Zircônio/química , Análise de Variância , Falha de Restauração Dentária , Materiais Dentários/química , Temperatura Alta , Teste de Materiais , Maleabilidade/efeitos dos fármacos , Estresse Mecânico , Propriedades de Superfície/efeitos dos fármacos , Fatores de Tempo , Resistência à Tração/efeitos dos fármacosRESUMO
PURPOSE: Quantify changes in the flexion--extension neutral zone of the intervertebral disc with injections of increasing genipin concentration. METHODS: Bovine motion segments were treated with varying concentrations of genipin using bilateral injections of constant volume. After overnight static compression loading of the treated segments, anterior-posterior offset loading was used to simulate flexion-extension motion. Range of motion, neutral zone length, neutral zone stiffness, and an instability score were measured. RESULTS: Injection of the disc annulus with increasing concentrations of genipin resulted in corresponding changes in flexion-extension neutral zone. A minimum concentration of 40 mM was needed to observe a significant change. The largest changes were observed with the 400 mM injection. Netural zone stability was the most sensitive of the metrics with a percent change of 48% at 40 mM and over 200% at 400 mM. CONCLUSION: This study establishes the efficacy of using injection delivery to affect disc joint mechanics and quantifies the dose response between injected genipin and the flexion-extension stability of the disc.
Assuntos
Disco Intervertebral/efeitos dos fármacos , Iridoides/administração & dosagem , Vértebras Lombares/efeitos dos fármacos , Amplitude de Movimento Articular/efeitos dos fármacos , Animais , Fenômenos Biomecânicos , Bovinos , Relação Dose-Resposta a Droga , Injeções , Disco Intervertebral/fisiologia , Vértebras Lombares/fisiologia , Teste de Materiais , Maleabilidade/efeitos dos fármacosRESUMO
INTRODUCTION: Recently, bioactive materials have been incorporated into glass ionomer cements to promote the precipitation of calcium phosphates in surrounding tooth structures. This in vitro study was undertaken to evaluate the effect of resin-modified glass ionomer (RMGI) containing bioactive glass (RMGI-BAG) on the flexural strength (FS) of demineralized dentin. MATERIALS AND METHODS: A total of 120 dentin bars (2×2×6 mm) were prepared from sound human third molars. Of these, 60 bars were immersed in a demineralizing solution for 96 hours. This produced dentin in two demineralization conditions (DC): untreated and demineralized. Each dentin bar was immersed for 14 days in simulated body fluid (SBF) at 37°C. Three immersion conditions (IC) were investigated: IC1-SBF only; IC2-SBF + an RMGI bar; IC3-SBF + an RMGI-BAG bar. The combination of the DCs and ICs produced six groups (n=20). FS values of the specimens were measured using a three-point bending test. The microstructural changes and the elemental contents of dentin surfaces were evaluated by scanning electron microscopy. Data were analyzed using a two-way analysis of variance (ANOVA) for the effects of the two independent variables, ie, DC and IC, on mean flexural strength. Tukey multiple comparison tests and simple main effects models were used as needed. The significance level of all tests was set at α=0.05. RESULTS: Both DC (p=0.001) and IC (p=0.049) significantly influenced FS (two-way ANOVA). The interaction between DC and IC did not significantly affect FS (p=0.36). For undemineralized dentin, IC did not affect the mean FS (simple main effects model; p=0.4). However, for demineralized dentin, IC significantly affected FS (small main effects model; p=0.008). The Tukey test showed that for demineralized dentin, the mean FS produced by immersion in SBF + RMGI-BAG was significantly stronger than that produced by either immersion in SBF only (p=0.011) or in SBF + RMGI (p=0.034). Scanning electron microscope/energy-dispersive x-ray spectroscopy analyses revealed more calcium and phosphate ions on the surface of dentin immersed in SBF + RMGI-BAG than on dentin immersed in SBF + RMGI. CONCLUSION: Immersion in SBF + RMGI-BAG increased the FS of demineralized dentin more than immersion in SBF + RMGI.
Assuntos
Cerâmica/farmacologia , Dentina/efeitos dos fármacos , Cimentos de Ionômeros de Vidro/farmacologia , Maleabilidade/efeitos dos fármacos , Desmineralização do Dente , Análise de Variância , Líquidos Corporais , Análise do Estresse Dentário , Dentina/química , Dentina/ultraestrutura , Cimentos de Ionômeros de Vidro/química , Humanos , Imersão , Teste de Materiais , Microscopia Eletrônica de Varredura , Estatísticas não ParamétricasRESUMO
Novel 3-C-alkylated-Neu5Ac2en derivatives have been designed to target the expanded active site cavity of influenza virus sialidases with an open 150-loop, currently seen in X-ray crystal structures of influenza A virus group-1 (N1, N4, N5, N8), but not group-2 (N2, N9), sialidases. The compounds show selectivity for inhibition of H5N1 and pdm09 H1N1 sialidases over an N2 sialidase, providing evidence of the relative 150-loop flexibility of these sialidases. In a complex with N8 sialidase, the C3 substituent of 3-phenylally-Neu5Ac2en occupies the 150-cavity while the central ring and the remaining substituents bind the active site as seen for the unsubstituted template. This new class of inhibitors, which can 'trap' the open 150-loop form of the sialidase, should prove useful as probes of 150-loop flexibility.
Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Vírus da Influenza A/enzimologia , Ácido N-Acetilneuramínico/análogos & derivados , Neuraminidase/antagonistas & inibidores , Alquilação , Domínio Catalítico/efeitos dos fármacos , Cristalografia por Raios X , Desenho de Fármacos , Inibidores Enzimáticos/química , Modelos Moleculares , Estrutura Molecular , Ácido N-Acetilneuramínico/síntese química , Ácido N-Acetilneuramínico/química , Ácido N-Acetilneuramínico/farmacologia , Neuraminidase/metabolismo , Maleabilidade/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
SJ-172550 (1) was previously discovered in a biochemical high throughput screen for inhibitors of the interaction of MDMX and p53 and characterized as a reversible inhibitor (J. Biol. Chem. 2010; 285:10786). Further study of the biochemical mode of action of 1 has shown that it acts through a complicated mechanism in which the compound forms a covalent but reversible complex with MDMX and locks MDMX into a conformation that is unable to bind p53. The relative stability of this complex is influenced by many factors including the reducing potential of the media, the presence of aggregates, and other factors that influence the conformational stability of the protein. This complex mechanism of action hinders the further development of compound 1 as a selective MDMX inhibitor.
Assuntos
Acetatos/farmacologia , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Pirazóis/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Acetatos/química , Sequência de Aminoácidos , Soluções Tampão , Proteínas de Ciclo Celular , Humanos , Concentração Inibidora 50 , Modelos Biológicos , Dados de Sequência Molecular , Proteínas Nucleares/química , Peptídeos/metabolismo , Maleabilidade/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Conformação Proteica , Estabilidade Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas/química , Pirazóis/química , Temperatura , Proteína Supressora de Tumor p53/químicaRESUMO
Neurodegeneration in protein-misfolding disease is generally assigned to toxic function of small, soluble protein aggregates. Largely, these assignments are based on observations of cultured neural cells where the suspect protein material is titrated directly into the growth medium. In the present study, we use this approach to shed light on the cytotoxic action of the metalloenzyme Cu/Zn superoxide dismutase 1 (SOD1), associated with misfolding and aggregation in amyotrophic lateral sclerosis (ALS). The results show, somewhat unexpectedly, that the toxic species of SOD1 in this type of experimental setting is not an aggregate, as typically observed for proteins implicated in other neuro-degenerative diseases, but the folded and fully soluble apo protein. Moreover, we demonstrate that the toxic action of apoSOD1 relies on the protein's ability to chelate Zn(2+) ions from the growth medium. The decreased cell viability that accompanies this extraction is presumably based on disturbed Zn(2+) homeostasis. Consistently, mutations that cause global unfolding of the apoSOD1 molecule or otherwise reduce its Zn(2+) affinity abolish completely the cytotoxic response. So does the addition of surplus Zn(2+). Taken together, these observations point at a case where the toxic response of cultured cells might not be related to human pathology but stems from the intrinsic limitations of a simplified cell model. There are several ways proteins can kill cultured neural cells but all of these need not to be relevant for neurodegenerative disease.
Assuntos
Quelantes/farmacologia , Superóxido Dismutase/toxicidade , Zinco/metabolismo , Sequência de Aminoácidos , Apoproteínas/toxicidade , Domínio Catalítico , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Ligantes , Modelos Biológicos , Dados de Sequência Molecular , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutação/genética , Neuroblastoma/patologia , Maleabilidade/efeitos dos fármacos , Multimerização Proteica/efeitos dos fármacos , Estabilidade Proteica/efeitos dos fármacos , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Soro , Superóxido Dismutase/química , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1 , Fatores de Tempo , Temperatura de Transição/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
OBJECTIVE: The purpose of this study was to evaluate the effect of the bleaching agents on the elastic modulus of bovine demineralized dentin matrix (EMDM). MATERIALS AND METHODS: Eighty-five slices were obtained from 17 bovine teeth. The slices were divided randomly into five experimental groups (n = 17): unbleached control group (CG), 4% hydrogen peroxide (HP4), 4% hydrogen peroxide + 0.05% Ca (HP4 + Ca), 7.5% hydrogen peroxide + ACP (HP7.5) and 10% carbamide peroxide (CP10). The HP4, HP4 + Ca and CP10 groups were treated with the bleaching agents for 8 h/day (14 days), while the samples of HP7.5 group were exposed to bleaching agent for 30 min twice a day (14 days). The CG was kept in 100% humidity. After bleaching treatments, the enamel of the samples was removed and 85 dentin beams (0.5 × 1.7 × 7.0 mm) were prepared. Afterwards, the beams were immersed in 10% phosphoric acid solution (5 h) and rinsed with water (10 min). The beams were tested after 24 h, 7 and 14 days of storage in distilled water, using three-point bend method. Data were statistically analyzed using ANOVA and Fisher's test. RESULTS: All bleaching treatments reduced the EMDM. After 14 days post-bleaching, the EMDM increased for HP4 and HP4+Ca groups. CONCLUSIONS: The use of bleaching agents promoted a decrease in EMDM, which indicates that the bleaching treatment interacts with the dentin organic matrix. The EMDM measurement for the specimens of the 7.5% hydrogen peroxide group that were immersed in water at 14 days post-bleaching did not recover the EMDM values when compared to the control group.
Assuntos
Dentina/efeitos dos fármacos , Clareadores Dentários/toxicidade , Clareamento Dental/efeitos adversos , Análise de Variância , Animais , Peróxido de Carbamida , Bovinos , Distribuição de Qui-Quadrado , Módulo de Elasticidade/efeitos dos fármacos , Dureza/efeitos dos fármacos , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/toxicidade , Teste de Materiais , Peróxidos/administração & dosagem , Peróxidos/toxicidade , Maleabilidade/efeitos dos fármacos , Distribuição Aleatória , Ureia/administração & dosagem , Ureia/análogos & derivados , Ureia/toxicidadeRESUMO
Dynamic RNA molecules carry out essential processes in the cell including translation and splicing. Base-pair interactions stabilize RNA into relatively rigid structures, while flexible non-base-paired regions allow RNA to undergo conformational changes required for function. To advance our understanding of RNA folding and dynamics it is critical to know the flexibility of these un-base-paired regions and how it depends on counterions. Yet, information about nucleic acid polymer properties is mainly derived from studies of ssDNA. Here we measure the persistence lengths (l(p)) of ssRNA. We observe valence and ionic strength-dependent differences in l(p) in a direct comparison between 40-mers of deoxythymidylate (dT(40)) and uridylate (rU(40)) measured using the powerful combination of SAXS and smFRET. We also show that nucleic acid flexibility is influenced by local environment (an adjoining double helix). Our results illustrate the complex interplay between conformation and ion environment that modulates nucleic acid function in vivo.
Assuntos
DNA de Cadeia Simples/química , RNA/química , Transferência Ressonante de Energia de Fluorescência , Íons , Cloreto de Magnésio/farmacologia , Modelos Moleculares , Concentração Osmolar , Maleabilidade/efeitos dos fármacos , Espalhamento a Baixo Ângulo , Cloreto de Sódio/farmacologia , Difração de Raios XRESUMO
Prolyl oligopeptidase (POP) is considered as an important pharmaceutical target for the treatment of numerous diseases. Despite enormous studies on various aspects of POPs structure and function still some of the questions are intriguing like conformational dynamics of the protein and interplay between ligand entry/egress. Here, we have used molecular modeling and docking based approaches to unravel questions like differences in ligand binding affinities in three POP species (porcine, human and A. thaliana). Despite high sequence and structural similarity, they possess different affinities for the ligands. Interestingly, human POP was found to be more specific, selective and incapable of binding to a few planar ligands which showed extrapolation of porcine POP in human context is more complicated. Possible routes for substrate entry and product egress were also investigated by detailed analyses of molecular dynamics (MD) simulations for the three proteins. Trajectory analysis of bound and unbound forms of three species showed differences in conformational dynamics, especially variations in ß-propeller pore size, which was found to be hidden by five lysine residues present on blades one and seven. During simulation, ß-propeller pore size was increased by â¼2 Å in porcine ligand-bound form which might act as a passage for smaller product movement as free energy barrier was reduced, while there were no significant changes in human and A. thaliana POPs. We also suggest that these differences in pore size could lead to fundamental differences in mode of product egress among three species. This analysis also showed some functionally important residues which can be used further for in vitro mutagenesis and inhibitor design. This study can help us in better understanding of the etiology of POPs in several neurodegenerative diseases.
Assuntos
Arabidopsis/enzimologia , Simulação de Dinâmica Molecular , Serina Endopeptidases/química , Sus scrofa/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Sequência Conservada , Inibidores Enzimáticos/farmacologia , Humanos , Ligação de Hidrogênio/efeitos dos fármacos , Ligantes , Lisina/metabolismo , Dados de Sequência Molecular , Maleabilidade/efeitos dos fármacos , Prolil Oligopeptidases , Ligação Proteica/efeitos dos fármacos , Estrutura Secundária de Proteína , Alinhamento de Sequência , Serina Endopeptidases/metabolismo , Especificidade da Espécie , Eletricidade Estática , Especificidade por Substrato/efeitos dos fármacos , TermodinâmicaRESUMO
INTRODUCTION: Controversy continues over the effects of bleaching treatments on tooth structures in the literature. In addition to tooth sensitivity, a number of studies have reported adverse effects of bleaching procedures on dental hard tissues, including decreased hardness, fracture toughness, flexural strength, and other changes in the mechanical properties. The purpose of this in vitro study was to investigate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application on the flexural strength (FS) of bleached teeth. METHODS AND MATERIALS: One hundred twenty blocks (2 × 3 × 8 mm) were prepared from the middle portion of the facial surfaces of 120 sound bovine teeth. Specimens were randomly divided into six groups (n=20). Group 1 consisted of the control group, stored in distilled water at 37 °C. The experimental groups (2 to 6) were immersed in CPP-ACP (0.5 h/d for 14 days, twice daily), 9.5% hydrogen peroxide (HP) (0.5 h/d, twice daily for 14 days), 9.5% HP+CPP-ACP, 38% HP (1 h/d, twice weekly for 2 weeks), and 38% HP+CPP-ACP, respectively. Flexural strength test was performed 24 hours after the last treatment session using a universal testing machine with a crosshead speed of 0.5 mm/min. Results were analyzed by two-way analysis of variance (ANOVA) and a post hoc Tukey's test (á=0.05). RESULTS: Mean ± SD values for FS were 179.50 ± 24.16, 194.00 ± 21.31, 155.25 ± 32.7, 177.50 ± 30.15, 158.50 ± 27.49, and 177.50 ± 28.09 MPa, respectively. Statistically significant differences were observed in FS values between groups (p<0.05). Tukey analysis showed that using CPP-ACP subsequent to both bleaching techniques has a significant effect on tooth flexural strength. CONCLUSION: Simulated in-office or at-home bleaching regimens performed in the absence of saliva decrease the FS of tooth structure. Application of CPP-ACP subsequent to both bleaching regimens could compensate for the decreased FS of the bovine enamel-dentin complex in this environment.
Assuntos
Cariostáticos/uso terapêutico , Caseínas/uso terapêutico , Clareadores Dentários/efeitos adversos , Clareamento Dental/efeitos adversos , Remineralização Dentária/métodos , Animais , Cariostáticos/farmacologia , Caseínas/farmacologia , Bovinos , Esmalte Dentário/efeitos dos fármacos , Análise do Estresse Dentário , Dentina/efeitos dos fármacos , Dureza/efeitos dos fármacos , Peróxido de Hidrogênio/efeitos adversos , Maleabilidade/efeitos dos fármacosRESUMO
PURPOSE: The aim of this study was to identify the presence of collagen-binding integrin subunits in human scleral fibroblasts (HSFs) and investigate their actual functions in maintaining the mechanical creep properties of the HSFs-seeded collagen matrix. METHODS: Primary HSFs were cultured in vitro. Reverse- transcription PCR was used to detect mRNA expression of integrin α1, α2, and ß1 subunits in HSFs. In addition, western blot analysis and immunofluorescence were used to detect their protein in HSFs. Monoclonal antibodies were applied directly against the extracellular domains of integrin subunits in HSFs cultured in the three-dimensional collagen gels to block the interaction between HSFs and the extracellular collagen matrix. The effects of anti-integrin antibodies on HSFs morphology in collagen gel were observed. The effects of the added antibodies on fibroblast-mediated collagen gels' contraction were evaluated. Furthermore, the changes in mechanical creep properties of collagen gel were measured by a biomechanics test instrument. RESULTS: The mRNA and protein expressions of collagen-binding integrin α1, α2, and ß1 subunits were present in HSFs. The elongated bipolar cells converted to spherical shapes after 6 h after the addition of integrin α1ß1 and α2ß1 antibody. The blocking of integrin α1ß1 and α2ß1 subunits noticeably decreased the contraction in the collagen gels. In addition, all samples were subjected to a constantly applied load of 0.03 N for 600 s. The blocking of integrin α1ß1 and α2ß1 subunits also induced increases in the values of final extension, creep extension, and creep rate, compared to those of the controls (p<0.01). Furthermore, the creep elements were significantly increased with the augmentation of the integrin antibody dose (p<0.01). The final extension of the integrin α2ß1 antibody (1 µg/ml or 4 µg/ml) group was significantly higher compared to that of the integrin α1ß1 antibody (1 µg/ml or 4 µg/ml) group (p<0.01). However, the creep extension and creep rate of the integrin α2ß1 antibody (1 µg/ml or 4 µg/ml) group were not significantly different from those in the integrin α1ß1 antibody (1 µg/ml or 4 µg/ml) group (p>0.05). CONCLUSIONS: Our findings suggested that HSF integrin α1ß1 and α2ß1 participated in maintaining the mechanical creep properties of the HSFs-seeded collagen matrix. Furthermore, integrin α2ß1 might play a more crucial role in maintaining the mechanical creep properties of the collagen matrix than does integrin α1ß1.
Assuntos
Anticorpos/farmacologia , Colágeno/metabolismo , Fibroblastos/metabolismo , Integrina alfa1beta1/metabolismo , Integrina alfa2beta1/metabolismo , Esclera/metabolismo , Adolescente , Animais , Fenômenos Biomecânicos , Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células , Proteínas do Olho/genética , Proteínas do Olho/metabolismo , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Géis/metabolismo , Humanos , Integrina alfa1/genética , Integrina alfa1/metabolismo , Integrina alfa1beta1/genética , Integrina alfa2/genética , Integrina alfa2/metabolismo , Integrina alfa2beta1/genética , Integrina beta1/genética , Integrina beta1/metabolismo , Maleabilidade/efeitos dos fármacos , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , RNA Mensageiro , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
The current study demonstrates vanadium plays the role of antitumor, and its antitumor effect is dosage-dependent. N-acetyl-galactosamine-transferase 2 (polypeptide: N-acetyl-α-galactosaminyl-transferases 2, ppGalNAc-T2) is a member of ppGalNAcTs (polypeptide: N-acetyl-α-galactosaminyl-transferases) family, which proves to play a vital role in the tumor emergence and development process. In this study, we focused on ppGalNAc-T2 and vanadium and aimed to determine whether ppGalNAc-T2 is correlated with vanadium's antitumor effect. We discovered that ppGalNAc-T2 changed with the variation of HL-60 cell growth induced by vanadium at mRNA level. Peanut agglutinin (PNA) is an exogenous lectin. PpGalNacT2 can be indirectly recognized by PNA. By means of flow cytometry and immunofluorescent staining, we found the deviation of PNA binding increased significantly at high concentration vanadium. Then we docked one of the possible compound substances of vanadium onto the body, VO(3) (molecular formula O(13)V(4), partial vanadate tetramer) and ppGalNAcT2, and simulated them via molecular dynamics, which showed that VO(3) may inhibit the activity of the enzyme by stemming conformational changes of a key loop of ppGalNAcT2. To sum up, our results suggested that ppGalNacT2 participated in vanadium induced HL-60 cell differentiation, which might be able to provide a new mechanism of vanadium's antitumor effect.
Assuntos
Diferenciação Celular/efeitos dos fármacos , N-Acetilgalactosaminiltransferases/metabolismo , Vanádio/farmacologia , Proliferação de Células/efeitos dos fármacos , Citometria de Fluxo , Fluoresceína-5-Isotiocianato/metabolismo , Fluorescência , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Células HL-60 , Humanos , Lectinas/metabolismo , Modelos Moleculares , N-Acetilgalactosaminiltransferases/química , N-Acetilgalactosaminiltransferases/genética , Aglutinina de Amendoim/metabolismo , Maleabilidade/efeitos dos fármacos , Polissacarídeos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Polipeptídeo N-AcetilgalactosaminiltransferaseRESUMO
Networks of the cytoskeletal biopolymer actin cross-linked by the compliant protein filamin form soft gels that stiffen dramatically under shear stress. We demonstrate that the elasticity of these networks shows a strong dependence on the mean length of the actin polymers, unlike networks with small, rigid cross-links. This behavior is in agreement with a model of rigid filaments connected by multiple flexible linkers.