首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
《Research in microbiology》2018,169(10):590-597
For the first time, synchrotron radiation (SR) -based carbon K-edge X-ray absorption near edge structure (XANES) spectroscopy in-situ characterization was conducted to evaluate the evolution of superficial (about 10 nm) organic components of extracellular polymeric substances (EPS) of thermoacidophilic archaeon Acidianus manzaensis YN-25 acclimated with different energy substrates (FeS2, CuFeS2, S0, FeSO4). The atomic force microscopy (AFM) morphology scanning showed that the strain acclimated with different energy substrates varied a lot in EPS amount. XANES results showed clear associations between the energy substrates and the changes in organic composition in terms of typical function groups (CO, CO and CN). The chalcopyrite- and pyrite-acclimated cells contained higher proportion of proteins but less proportion of polysaccharides than the S0-acclimated cells. The FeSO4-acclimated cells contained the highest proportion of proteins, while the S0-acclimated cells contained more lipids and polysaccharides. The results of linear-combination and peak fitting of the K-edge XANES for the extracellular superficial organic component C is consistent with the trend in comparison with the results of FTIR and spectrophotometric determination, but there are significant differences in the values. These differences are caused by the inconsistencies of measurement depth between XANES and the latter two characterization methods.  相似文献   

2.
《Acta biomaterialia》2014,10(7):3317-3326
Owing to their adjustable dissolution properties, phosphate-based glasses (PGs) are promising materials for the controlled release of bioinorganics, such as copper ions. This study describes a vapour sorption method that allowed for the investigation of the kinetics and mechanisms of aqueous interactions of PGs of the formulation 50P2O5–30CaO–(20–x)Na2O–xCuO (x = 0, 1, 5 and 10 mol.%). Initial characterization was performed using 31P magic angle spinning nuclear magnetic resonance and attenuated total reflectance–Fourier transform infrared spectroscopy. Increasing CuO content resulted in chemical shifts of the predominant Q2 NMR peak and of the (POP)as and (PO) Fourier transform infrared absorptions, owing to the higher strength of the POCu bond compared to PONa. Vapour sorption and desorption were gravimetrically measured in PG powders exposed to variable relative humidity (RH). Sorption was negligible below 70% RH and increased exponentially with RH from 70 to 90%, where it exhibited a negative correlation with CuO content. Vapour sorption in 0% and 1% CuO glasses resulted in phosphate chain hydration and hydrolysis, as evidenced by protonated Q0(1H) and Q1(1H) species. Dissolution rates in deionized water showed a linear correlation (R2 > 0.99) with vapour sorption. Furthermore, cation release rates could be predicted based on dissolution rates and PG composition. The release of orthophosphate and short polyphosphate species corroborates the action of hydrolysis and was correlated with pH changes. In conclusion, the agreement between vapour sorption and routine characterization techniques in water demonstrates the potential of this method for the study of PG aqueous reactions.  相似文献   

3.
Poly(butylene succinate), a novel biodegradable aliphatic polyester with excellent processability and mechanical properties, was modified by O2 or N2 plasma immersion ion implantation (PIII). X-ray photoelectron spectroscopy and contact angle measurements were carried out to reveal the surface characteristics of the treated and control specimens. The in vitro effects of the materials on seeded osteoblasts were detected by cell viability assay, alkaline phosphatase activity test, and real-time polymerase chain reaction analysis. Plate counting was performed to investigate the antibacterial properties. Our results show that both PIII treatments significantly improve the hydrophilicity of PBSu, and CO and nitrogen groups (CNH and CNH2) can be detected on the PBSu after O2 and N2 PIII, respectively. The modified samples exhibit similar compatibility to osteoblasts, which is better than that of the control, but O2 PIII and N2 PIII produce different effects according to the osteogenic gene expressions of seeded osteoblasts on the materials. Moreover, the N2 plasma-modified PBSu exhibits anti-infection effects against Staphylococcus aureus and Escherichia coli but no such effects can be achieved after O2 PIII.  相似文献   

4.
《Acta histochemica》2014,116(8):1359-1366
Histological and histochemical observations support the hypothesis that collagen fibers can link to elastic fibers. However, the resulting organization of elastin and collagen type complexes and differences between these materials in terms of macromolecular orientation and frequencies of their chemical vibrational groups have not yet been solved. This study aimed to investigate the macromolecular organization of pure elastin, collagen type I and elastin–collagen complexes using polarized light DIC-microscopy. Additionally, differences and similarities between pure elastin and collagen bundles (CB) were investigated by Fourier transform-infrared (FT-IR) microspectroscopy. Although elastin exhibited a faint birefringence, the elastin–collagen complex aggregates formed in solution exhibited a deep birefringence and formation of an ordered-supramolecular complex typical of collagen chiral structure. The FT-IR study revealed elastin and CB peptide NH groups involved in different types of H-bonding. More energy is absorbed in the vibrational transitions corresponding to CH, CH2 and CH3 groups (probably associated with the hydrophobicity demonstrated by 8-anilino-1-naphtalene sulfonic acid sodium salt [ANS] fluorescence), and to νCN, δNH and ωCH2 groups of elastin compared to CB. It is assumed that the α-helix contribution to the pure elastin amide I profile is 46.8%, whereas that of the B-sheet is 20% and that unordered structures contribute to the remaining percentage. An FT-IR profile library reveals that the elastin signature within the 1360–1189 cm−1 spectral range resembles that of Conex–Toray aramid fibers.  相似文献   

5.
The role of roughening and functionalization processes involved in modifying the wettability of poly(ε-caprolactone) (PCL) after treatment by an atmospheric pressure glow discharge plasma is discussed. The change in the ratio of CO/C–O bonds is a significant factor influencing the wettability of PCL. As the contact angle decreases, the level of CO bonds tends to rise. Surface roughness alterations are the driving force for lasting increases in wettability, while the surface functional species are shorter lived. We can approximate from ageing that the increase in wettability for PCL after plasma treatment is 55–60% due to roughening and 40–45% due to surface functionalization for the plasma device investigated.  相似文献   

6.
《Molecular immunology》2014,58(2):236-246
The use of methoxypoly(ethylene glycol) (mPEG) in PEG conjugates of proteins and non-protein therapeutic agents has led to the recognition that the polymer components of such conjugates can induce anti-PEG antibodies (anti-PEGs) that may accelerate the clearance and reduce the efficacy of the conjugates. Others have classified anti-PEGs as “methoxy-specific” or “backbone-specific”. The results of our previous research on anti-PEGs in the sera of rabbits immunized with mPEG or hydroxyPEG (HO-PEG) conjugates of three unrelated proteins were consistent with that classification (Sherman, M.R., et al., 2012. Bioconjug. Chem. 23, 485–499). Enzyme-linked immunosorbent assays (ELISAs) were performed on rabbit antisera and rabbit monoclonal anti-PEGs with competitors including 10 kDa mPEG, 10 kDa PEG diol and six linear or cyclic oligomers of oxyethylene (CH2CH2O), with molecular weights of ca. 150–264 Da. Our results demonstrate that (1) the binding affinities of anti-mPEGs depend more on the backbone lengths of the polymers and the hydrophobicities of their end-groups than on their resemblance to the methoxy terminus of the immunogenic polymer; (2) anti-PEGs raised against HO-PEG-proteins are not directed against the terminal hydroxy group, but against the backbone; (3) rabbit anti-PEGs bind to and distinguish among PEG-like oligomers with as few as three oxyethylene groups; and (4) none of the monoclonal or polyclonal anti-PEGs was absolutely “methoxy-specific” or “backbone-specific”, but displayed distinct relative selectivities. If these results are relevant to human immune responses, the clinical use of stable conjugates of HO-PEG with proteins and non-protein therapeutic agents would be expected to produce fewer and less intense immune responses than those induced by conjugates with mPEG or PEGs with larger alkoxy groups.  相似文献   

7.
The alga Sargassum dentifolium (Turner) C. Agardh, belongs to Sargassaceae, is a brown seaweed in red sea shores in Egypt. This work aimed to extract different water-soluble polysaccharide extracts (E1, E2, and E3) from S. dentifolium and to investigate their protective effect against cyclophosphamide (CP)-induced genotoxicity. Mice bone marrow cells (BMCs) were collected and analyzed for the chromosomal aberration, micronucleated BMCs (MN-BMCs), the mitotic index, DNA fragmentation by comet assay, and histone deacetylases (HDACs), and radical scavenging capacity of extracts was evaluated by the oxygen radical absorbance capacity assay.The results indicated that E2 and E3 significantly inhibited CP-induced multiple chromosomal aberrations, where E1 and E3 significantly suppressed the number of CP-induced formation of tetraploidy. The extracts prohibited the cytotoxic effect of CP and recovered the mitotic activity, whereas E1 possessed the highest recovery and mitosis. In absence of MN, CP induced formation of bi- and poly-nucleated BMCs. E1 prohibited CP-induced formation of bi-nucleated BMCs, while E2 and E3 prohibited CP-induced formation of poly-nucleated BMCs. CP-induced MN-BMCs were accompanied with mono-, bi- and poly-nucleated cells. E1 and E3 remarkably suppressed mono-nucleated MN-BMCs, while E2 inhibited bi-nucleated MN-BMCs. All the extracts significantly inhibited the CP-induced formation of poly-nucleated MN-BMCs. CP-induced DNA fragmentation was inhibited by all extracts, where E1 was the strongest inhibitor as concluded from the comet tail moment. All the extracts were strong OH scavengers, while only E3 was ROO scavenger. The results revealed a drastic decline in HDACs activity by E1 and E3. In conclusion, S. dentifolium polysaccharide extracts E1 and E3 possessed a potential anti-genotoxic and a promising anti-mutagenic activity.  相似文献   

8.
Previously reported experiments suggest that healing intention focused toward water, or merely taking place in the vicinity of water, affects the hydrogen-oxygen (HO) covalent bonds. This claim was explored in the context of a clinical energy medicine pilot study involving 17 practitioners and 190 participants. In a “direct” test, samples of water were directly treated by the practitioners; in an “indirect” test, aliquots attached to lanyards were worn by practitioners and participants as they were engaged in healing sessions. Samples of laboratory-grade distilled water and Fiji brand water were used in the tests, and the water was analyzed using an Attenuated Total Reflection (ATR) Fourier Transform Infrared (FTIR) spectrometer equipped with a liquid nitrogen-cooled detector. The comparison of interest was the ensemble average spectrum recorded during pre- vs. post-intentional healing periods in the primary infrared absorption portion of the water spectrum.The analyses indicated that distilled water directly treated by the practitioners resulted in a change in the HO bond at the wavenumber 3200 cm?1 (p < 0.03, two-tailed). No effect was observed with the Fiji water. The distilled water in aliquots worn by practitioners also resulted in a significant change at the same wavenumber (p = 0.0004, two-tailed). No effects were observed in Fiji water aliquots worn by practitioners or participants, or in distilled water worn by participants.This study contributes to previously reported observations suggesting that the structure of water reacts in an anomalous way to healing intentions. Such effects appear to involve some form of energetic influence, but that is not yet well established. Nor is it certain that the observed effect can only be due to intention; it is conceivable, for example, that an unidentified environmental factor may have been responsible for the observed comparisons. However, given similar results observed in several experiments so far, including the present study, further research seems warranted.  相似文献   

9.
10.
《Immunobiology》2020,225(1):151864
PurposeAutoimmune diseases are a group of complex diseases localized in multiple organ systems, with a wide spectrum of symptoms and still unclear causes. The aim of the present study was to analyse a possible association of three autoimmune disabilities - Multiple sclerosis (MS), LADA diabetes and Graves’ disease (GD) with single nucleotide polymorphism (SNP; rs1990760) in the IF IH1 gene (also known as a melanoma differentiation-associated protein 5 - MDA5) within the Polish population. An additional goal was also to look for a correlation between this polymorphism and different clinical patient-related factors.Materials and methodsThe study population consisted of four groups of 944 unrelated Polish origin Caucasian patients – 324 with GD, 171 with MS, 49 with LADA diabetes and 400 healthy subjects as a control group. The SNP analysis was performed using the allelic discrimination technique.Results & ConclusionsThere were significant associations of risk T allel of the analyzed polymorphism with all studied autoimmune diseases (GDOR = 1.34, p = 7.02e-03; MSOR = 1.36, p = 2.17e-02; LADA – OR = 3.36, p = 8.73e-07). We also found that the frequency of CT and TT genotypes of the rs1990760 IFIH1 gene only in females (with LADA, GD, MS) was significantly higher than those in the female control group (47%, 41% vs 44%, 34%; p = 1.32e-03, p = 4.39e-04; OR = 2.08, 95%CI: (1.33–3.28), OR = 2.29, 95% CI: (1.44–3.65) respectively). Our research has shown significant differences regarding some clinical features (BMI, TRAb, TSH, HbA1C, anti-GAD antibodies) and age at the beginning of the studied autoimmune disabilities. This study showed an association of rs1990760 polymorphism in the IFIH1 gene in the development of GD, LADA diabetes and MS within the Polish population. To our knowledge, this is the first study to investigate the relationship between IFIH1 polymorphisms and the risk of the development of MS and LADA in Poland.  相似文献   

11.
《Acta biomaterialia》2014,10(2):821-830
Advanced bioactive systems with defined macroscopic properties and spatio-temporal sequestration of extracellular biomacromolecules are highly desirable for next generation therapeutics. Here, chitosan (CT) hydrogels were prepared with neutral or negatively charged cross-linkers in order to promote selective electrostatic complexation with charged drugs. CT was functionalized with varied dicarboxylic acids, such as tartaric acid, poly(ethylene glycol) bis(carboxymethyl) ether, 1,4-phenylenediacetic acid and 5-sulfoisophthalic acid monosodium salt (PhS), whereby PhS was hypothesized to act as a simple mimetic of heparin. Attenuated total reflectance Fourier transform infrared spectroscopy showed the presence of CO amide I, N–H amide II and CO ester bands, providing evidence of covalent network formation. The cross-linker content was reversely quantified by proton nuclear magnetic resonance on partially degraded network oligomers, so that 18 mol.% PhS was exemplarily determined. Swellability (SR: 299 ± 65–1054 ± 121 wt.%), compressibility (E: 2.1 ± 0.9–9.2 ± 2.3 kPa), material morphology and drug-loading capability were successfully adjusted based on the selected network architecture. Here, hydrogel incubation with model drugs of varied electrostatic charge, i.e. allura red (AR, doubly negatively charged), methyl orange (MO, negatively charged) or methylene blue (MB, positively charged), resulted in direct hydrogel–dye electrostatic complexation. Importantly, the cationic compound, MB, showed different incorporation behaviours, depending on the electrostatic character of the selected cross-linker. In light of this tunable drug-loading capability, these CT hydrogels would be highly attractive as drug reservoirs towards e.g. the fabrication of tissue models in vitro.  相似文献   

12.
Polymer–clay nanocomposite (P‐NC) microspheres are synthesized through in situ free‐radical polymerization in aqueous media without the use of surfactants. Uniform aqueous dispersions of P‐NC microspheres without flocculation/precipitation are obtained for five types of (co)polymers with different hydrophilic/hydrophobic natures, in which the exfoliated clay platelets play an important role as crosslinkers and stabilizers in water. The sol–gel boundary, transparency of the aqueous dispersion, microsphere particle size, etc. vary depending on the compositions and polymerization methods. Aqueous dispersions of P‐NC microspheres with a well‐defined lower critical solution temperature (LCST)‐type thermosensitive transition are obtained by using N‐isopropylacrylamide (NIPA), 2‐methoxyethylacrylate (MEA), and N,N‐dimethylacrylamide (DMAA) as the (co)monomers. In the case of P‐NC microspheres consisting of inorganic clay and NIPA‐DMAA or MEA‐DMAA copolymers, the LCST is controlled over a wide range, particularly depending on the DMAA content. The P‐NC microspheres applied within double‐layer glass plates are examined as reversible and efficient thermosensitive optical shutters.

  相似文献   


13.
The genotoxicity of silicon (Si) is investigated by soaking crystalline Si in a complete culture medium for 60 days and conducting micronuclei tests (MNTs) utilizing hamster ovary (CHO) cells and its Ku80 deficient CHO mutant (xrs5) cells (DNA double-strand breaks repair deficiency). The intracellular concentrations of reactive oxygen/nitrogen species (ROS/RNS) on Si are determined to elucidate the relationship between ROS/RNS and Si-induced genotoxicity by using CHO cells. The cells are treated with ROS scavenger (dimethyl sulfoxide) and MNT are performed. The results indicate that the intracellular concentration of ROS and nitrogen oxide (NO) on Si is higher than those on the control group by about 38% and 12%. ROS/RNS include superoxide (O2?) anion, NO, and peroxynitrite (ONOO?) which can injure chromosomes and induce high cellular DNA double-strand breaks (DSBs).  相似文献   

14.
The antioxidant activity of [N, N′-Bis (salicylidene) ethane-1, 2-diaminato] oxovanadium (IV) complex (VO-salen complex) was evaluated using different in vitro evaluating systems including superoxide anion (O2?) and hydrogen peroxide (H2O2) scavenging activities. In addition, the inhibitory effects of this compound on protein oxidation and inhibition of Fe2+/ascorbate-induced lipid peroxidation were studied using rat liver homogenate. In vitro results revealed that the VO-salen complex has strong inhibitory effects on protein oxidation and lipid peroxidation of the liver homogenate along with a concentration-dependent quenching of H2O2 and O2? radicals. In an in vivo approach, hepatoprotective potential of the VO-salen complex against liver damages induced by CCl4 treatment was also investigated. After intraperitoneal injection of CCl4 to rats, various biochemical changes associated with liver injury and/or oxidative stress were measured. The results showed that the sera levels of ALT, AST, ALP and the content of hepatic thiobarbituric acid reactive substances (TBARS) were all increased and the glutathione (GSH) content and the hepatic superoxide dismutase (SOD) and catalase (CAT) activities were decreased in CCl4-treated rats. However, simultaneous treatment of rats with VO-salen (0.6 mg/kg) and CCl4 significantly attenuated the sera levels of ALT, AST, ALP and the hepatic TBARS content. In addition, by VO-salen therapy, the hepatic SOD and CAT activities and the GSH content were all restored back almost to their normal levels. The liver damages were also significantly ameliorated as compared to the CCl4-treated rats. Based on these results, the VO-salen complex might be considered as an effective antioxidant and hepatoprotective agent suitable for further biological evaluation.  相似文献   

15.
PurposeDaratumumab is a promising new agent for relapsed/refractory multiple myeloma (RRMM). However, there are limited data on its clinical activity and tolerability in the real-world patients. The purpose of this study is to determine the efficacy and toxicity profile of daratumumab monotherapy in the real-life setting.Patients and methodsThirty RRMM patients treated with daratumumab who had previously received at least three treatment lines including a proteasome inhibitor and an immunomodulatory drug or had been double refractory (DRMM) were included to the Polish Myeloma Group observational study.ResultsThe objective response rate to daratumumab was 42.8%. Median progression-free survival (PFS) and overall survival reached 9.5 and 13.8 months, respectively. Importantly, patients with DR-MM had a significantly shorter PFS than other patients (median PFS of 4.1 vs. 12.1 months). Daratumumab was generally well tolerated, however two patients had their therapy interrupted due to adverse events.ConclusionDaratumumab monotherapy has significant activity and good tolerance in heavily pretreated RRMM patients.  相似文献   

16.
A glucose-sensitive multilayer shell, which was fabricated by the layer-by-layer (LbL) assembly method, can be used as a carrier for the encapsulation and controlled release of insulin. In the present report, glucose oxidase (GOD) and catalase (CAT) were assembled on insulin particles alternately via glutaraldehyde (GA) cross-linking. The resulting core–shell system has been proven to be glucose-sensitive. When the external glucose was introduced, the release ratio of insulin from the protein multilayer can be increased observably. This is likely attributed to the catalysis interaction of CAT/GOD shells to glucose, which leads to the production of H+ and thus drops the pH of the microenvironment. Under the acidic conditions, on the one hand, a part of CN bond formed from Schiff base reaction can be broken and thus increasing the permeability of the capsule wall. On the other hand, the solubility of insulin can also be increased. The above factors may be the key control to increase the release of insulin from the multilayer. Therefore, such CAT/GOD multilayer may have a great potential as a glucose-sensitive release carrier for insulin, and may open the way for the further application of LbL capsules in the drug delivery and controlled release, etc.  相似文献   

17.
18.
Here, we report a new method to predict the appropriate size of drugs which can be entrapped in and released from a hydrogel with pendant thermosensitive units by a strict "on-off" mechanism. Moreover, the valve-type action of the thermosensitive arms has been investigated. Inverse size exclusion chromatography (ISEC) and environmental scanning electron microscopy (ESEM) have been used to characterize the extension and collapse of the pendant thermosensitive units, below and above the lower critical solution temperature (LCST) under physiological conditions, confirming the hypothesis postulated by the "arid" theoretical models. The functionalized pullulan (Pul) microspheres, here prepared, were coupled with thermoresponsive oligomers by reaction between the -NH? end-group of oligomers and chlorine present on Pul microspheres. The Pul microspheres with temperature sensitive moieties were packed in a glass column and the elution volume of standard molecule with well-known molecular weights (radius of gyration) was determined below and above the LCST. FITC-Dextran 4000 diffused through the pores of Pul microspheres with short thermosensitive arms (Mw = 1500 g/mol) both below and above the LCST of the thermosensitive units. In contrast, Pul microspheres with long thermosensitive arms (Mw = 3300 g/mol) allowed the diffusion of FITC-Dextran 4000 only above the LCST of the thermosensitive units. Indeed, the long thermosensitive arms are extended below the LCST and FITC-Dextran 4000 is completely excluded from the pores. The loading/release profile of this model molecule follows an "on-off" mechanism, confirming the results obtained by ISEC. ESEM was used as a new technique, taking images of the surface of the thermosensitive pullulan microspheres in their natural swollen state, with no prior specimen preparation, below and above the LCST. The low toxicity of pullulan microspheres observed below and above the LCST of thermosensitive units at high concentrations (10 mg/ml) recommends their potential use for controlled drug delivery applications.  相似文献   

19.
20.
Using poly(vinyl alcohol) as a drug model, the swelling behaviors of thermosensitive poly(N‐isopropylacrylamide) gel with various concentrations of PVA are investigated. The swelling ratio in PVA9000 is larger than that of PVA89000 at the same composition because the fully hydrolyzed PVA acts as a steric hindrance. A lattice‐based molecular thermodynamic model is used to obtain interaction parameters and then directly applied to describe the swelling behaviors of the gel. Using only one adjustable parameter, the PVA selectivity can be theoretically predicted and the ternary phase diagrams of PNIPA/water/PVA system can be generated. Lastly, the calculated results are compared with the swelling data for PNIPA/PVA copolymer gel, and are found to be in good agreement with the proposed model.

  相似文献   


设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号