HA Complex Research Articles

Skin antiaging effects of a multiple mechanisms hyaluronan complex.

Intrinsic skin aging is an inevitable process with reduced extracellular matrix deposition and impaired mechanical integrity in the dermal-epidermal junction (DEJ). Hyaluronan is one of the most promising natural ingredients. In this research, multiple mechanisms of a novel hyaluronan complex against intrinsic skin aging were revealed. Immunohistochemical analysis and enzyme-linked immunosorbent assay were employed to evaluate the effect of low-molecular weight sodium hyaluronan, its acetylated derivative and HA complex on expression of matrix metalloproteinase-1 (MMP-1) and type I collagen in normal human fibroblasts. Then, immunohistochemical analysis and hematoxylin and eosin staining was carried out to evaluate identical effects of HA complex in reconstructed skin equivalents, as well as its benefits on histological structure and DEJ. In normal human dermal fibroblasts, the hyaluronan complex, which contains low-molecular weight sodium hyaluronate and its acetylated derivative, has synergistic effects by increasing type I collagen expression. At the same time, MMP-1 production was inhibited. This was confirmed in subsequent experiments with skin equivalent, and intriguingly, the hyaluronan complex was also found to increase the expression of two DEJ proteins. The multimechanism hyaluronan complex in this proof-of-concept study exhibited skin antiaging effects in vitro through inhibiting the expression of MMP-1 and enhancing type I collagen accumulation and the expression of DEJ proteins, which reveals new avenues for investigating more biological activities of various types of hyaluronan.

Grafted Chitosan-Hyaluronic Acid (CS-g-poly (MA-co-AN) HA) Complex Inhibits Fluconazole-Resistant Candida albicans Biofilm Formation.

Fungal resistance that leads to the failure of drug therapy due to biofilm development is a major clinical challenge. Various polysaccharides have been used to control biofilm formation by drug-resistant fungi, and this study was undertaken to develop chitosan (CS)-modified materials and evaluate their abilities to inhibit Candida biofilm growth. CS was grafted with methacrylamide (MA) and acrylonitrile (AN) and, to improve its application characteristics further, was grafted with hyaluronic acid to produce CS-g-poly (MA-co-AN) HA complex. Grafting and complex formation were confirmed using spectroscopic techniques. CS-g-poly (MA-co-AN) HA was tested to investigate its ability to inhibit Candida albicans biofilm formation and showed significant antibiofilm activity at 200 µg/mL. Additionally, CS-g-poly (MA-co-AN) HA did not have any toxic effect on Caenorhabditis elegans. Thus, this study provides an innovative means of preventing microorganism-associated biofilm formation.

Hydroxylamine Complexes of Cytochrome c': Influence of Heme Iron Redox State on Kinetic and Spectroscopic Properties.

Hydroxylamine (NH2OH or HA) is a redox-active nitrogen oxide that occurs as a toxic intermediate in the oxidation of ammonium by nitrifying and methanotrophic bacteria. Within ammonium containing environments, HA is generated by ammonia monooxygenase (nitrifiers) or methane monooxygenase (methanotrophs). Subsequent oxidation of HA is catalyzed by heme proteins, including cytochromes P460 and multiheme hydroxylamine oxidoreductases, the former contributing to emissions of N2O, an ozone-depleting greenhouse gas. A heme-HA complex is also a proposed intermediate in the reduction of nitrite to ammonia by cytochrome c nitrite reductase. Despite the importance of heme-HA complexes within the biogeochemical nitrogen cycle, fundamental aspects of their coordination chemistry remain unknown, including the effect of the Fe redox state on heme-HA affinity, kinetics, and spectroscopy. Using stopped-flow UV-vis and resonance Raman spectroscopy, we investigated HA complexes of the L16G distal pocket variant of Alcaligenes xylosoxidans cytochrome c'-α (L16G AxCP-α), a pentacoordinate c-type cytochrome that we show binds HA in its Fe(III) (Kd ∼ 2.5 mM) and Fe(II) (Kd = 0.0345 mM) states. The ∼70-fold higher HA affinity of the Fe(II) state is due mostly to its lower koff value (0.0994 s-1 vs 11 s-1), whereas kon values for Fe(II) (2880 M-1 s-1) and Fe(III) (4300 M-1 s-1) redox states are relatively similar. A comparison of the HA and imidazole affinities of L16G AxCP-α was also used to predict the influence of Fe redox state on HA binding to other proteins. Although HA complexes of L16G AxCP-α decompose via redox reactions, the lifetime of the Fe(II)HA complex was prolonged in the presence of excess reductant. Spectroscopic parameters determined for the Fe(II)HA complex include the N-O stretching vibration of the NH2OH ligand, ν(N-O) = 906 cm-1. Overall, the kinetic trends and spectroscopic benchmarks from this study provide a foundation for future investigations of heme-HA reaction mechanisms.

Imine Bond- and Coordinate Bond-Linked pH-Sensitive Cisplatin Complex Nanoparticles for Active Targeting to Tumor Cells.

Aldehyde hyaluronic acid-cisplatin (A-HA-CDDP) complex nanoparticles were readily prepared, and CDDP was stably loaded into the core of the NPs through imine bond and coordinate bond linkages. The results show that the NPs were prepared successfully by a chemical complexation reaction rather than by physical mixing. Compared to many CDDP and HA complex nanoparticles evaluated in other studies, A-HA-CDDP NPs with imine and coordinate bonds between the A-HA and CDDP displayed better sustained release behavior and pH sensitivity. Therefore, the acidic tumor environment could accelerate the release of CDDP from the NPs. MTT and AO/EB staining assays showed that A-HA-CDDP NPs had comparable cell inhibition with CDDP in HeLa cells as well as little toxicity to NIH3T3 cells. This result indicates that the chemical reaction between A-HA and CDDP had little effect on the antitumor activity of CDDP and that the NPs actively targeted CD44-rich tumor cells. Both a hemolysis test and a protein adsorption assay demonstrated that A-HA-CDDP NPs had good biocompatibility and blood circulation in vivo. Therefore, the NPs have the potential to be used for targeted CDDP delivery in vivo. A subsequent publication will describe the circulation, targeting and tumor inhibition experiments of these NPs in vivo.

Fabrication and Comprehensive Characterization of Biomimetic Extracellular Matrix Electrospun Scaffold for Vascular Tissue Engineering Applications

The collagen–hyaluronic acid oligosaccharides (collagen–HA) complex was obtained by covalent attachment using EDC/NHS. The cross-linked product collagen–HA had been confirmed by Fourier transform infrared spectra (FTIR) and the sulfuric acid–carbazole colorimetry, and factors that affect the cross-linking process were investigated. Electrospinning of collagen–HA complex in hexafluoroisopropanol was investigated for the biomimetic nanostructure and biocompatible vascular tissue-engineered inner-layer scaffold. The morphology of the electrospun collagen–HA nanofibers with a series of concentrations was observed by scanning electron microscopy. The thermal behavior and chemical properties of the fabricated scaffolds were characterized using dynamic scanning calorimetry and FTIR after being stabilized by glutaraldehyde vapor. The cell attachment, morphology and proliferation of porcine iliac artery endothelial cells (PIECs) on the electrospun scaffolds were also evaluated. The results indicate that the biomimetic matrix collagen–HA electrospun nanofibrous scaffold could promote PIECs proliferation and may be a better candidate with endothelial potential for the vascular tissue-engineered inner-layer scaffold.

Gene Therapy and Photothermal Therapy of Layer-by-Layer Assembled AuNCs /PEI/miRNA/ HA Nanocomplexes.

MicroRNA (miRNA) therapy, which was widely considered to treat a series of cancer, has been confronted with numerous obstacles to being delivered into target cells because of its easy biodegradation and instability. In this research, we successfully constructed 11-mercaptoundecanoic acid modified gold nanocages (AuNCs)/polyethyleneimine (PEI)/miRNA/hyaluronic acid (HA) complexes (abbreviated as AuNCs/PEI/miRNA/HA) using a layer-by-layer method for target-specific intracellular delivery of miRNA by HA receptor mediated endocytosis. The results of UV spectra, hydrodynamic diameter and zeta potential analyses confirmed the formation of AuNCs/PEI/ miRNA/HA complex with its average particle size of ca. 153 nm and surface charge of ca. -9.43 mV. Next, we evaluated the antitumor effect of the nanocomplex mediated by the combination of gene therapy and photothermal therapy (PTT) against hepatocellular carcinoma (HCC) in vitro. Our experimental results indicated that the AuNCs/PEI/miRNA/HA complex effectively delivered miRNA to the target cells and its antitumor effect was significantly enhanced by the combination of gene therapy and photothermal therapy. In addition, anti-miR-181b could promote Bel-7402 cell arrest in S phase and improve TIMP-3 mRNA expression. All these results suggested that AuNCs/PEI/miRNA/HA gene delivery system with combination of gene therapy and photothermal therapy might be exploited for HCC treatment.

Research progress in broad neutralizing antibodies and universal vaccines against influenza A virus

Influenza vaccination is the most effective means to prevent and control influenza epidemics, and the universal influenza vaccine which can induce broad and long-term protective effect is still in its infancy. Up to date, several broad neutralizing antibodies that can antagonize a variety of influenza A viruses have been identified, and the crystal structure of the antibody and HA complex reveals at least three highly conserved epitopes. Deep insights into the molecular mechanism of the interactions between neutralizing antibodies and virus antigen can elicit a new strategy not only for rational design of universal influenza vaccines, but also for the development of antibody-based therapeutics against influenza virus. In this paper, advances in research of universal neutralizing antibodies and vaccines for Influenza A virus are reviewed. Key words: Influenza A virus; Heamagglutinin; Epitope; Broad neutralizing antibody; Vaccine

Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes

Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE–HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO–OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17mg/g)>FH-HA (5.43mg/g)>GE (4.67mg/g)>GE-HA (3.27mg/g). After coating with HA, the amorphous FH–HA complex still showed higher P adsorption than the crystalline GE–HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO–HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas.

Inhibiting oral intoxication of botulinum neurotoxin A complex by carbohydrate receptor mimics

Botulinum neurotoxins (BoNTs) cause the disease botulism manifested by flaccid paralysis that could be fatal to humans and animals. Oral ingestion of the toxin with contaminated food is one of the most common routes for botulism. BoNT assembles with several auxiliary proteins to survive in the gastrointestinal tract and is subsequently transported through the intestinal epithelium into the general circulation. Several hemagglutinin proteins form a multi-protein complex (HA complex) that recognizes host glycans on the intestinal epithelial cell surface to facilitate BoNT absorption. Blocking carbohydrate binding to the HA complex could significantly inhibit the oral toxicity of BoNT. Here, we identify lactulose, a galactose-containing non-digestible sugar commonly used to treat constipation, as a prototype inhibitor against oral BoNT/A intoxication. As revealed by a crystal structure, lactulose binds to the HA complex at the same site where the host galactose-containing carbohydrate receptors bind. In vitro assays using intestinal Caco-2 cells demonstrated that lactulose inhibits HA from compromising the integrity of the epithelial cell monolayers and blocks the internalization of HA. Furthermore, co-administration of lactulose significantly protected mice against BoNT/A oral intoxication in vivo. Taken together, these data encourage the development of carbohydrate receptor mimics as a therapeutic intervention to prevent BoNT oral intoxication.

Complexation of Hypocrellin A with Al3+ in water solution and the photodynamic therapy study

The complex of Hypocrellin A with Al3+ is prepared in water solution by a facile method. The water-solubility and stability of complexes are improved. Irradiation of Al3+–HA complex results in higher efficient generation of singlet oxygen (1O2) and photocleavage ability to CT DNA than HA. In vitro studies have illustrated that the Al3+–HA complex has anti-cancer activity.

Zinc Induces Dimerization of the Class II Major Histocompatibility Complex Molecule That Leads to Cooperative Binding to a Superantigen

Dimerization of class II major histocompatibility complex (MHC) plays an important role in the MHC biological function. Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing specific T cell receptor Vbeta elements. Here we have used structural, sedimentation, and surface plasmon resonance detection approaches to investigate the molecular interactions between MAM and the class II MHC molecule HLA-DR1 in the context of a hemagglutinin peptide-(306-318) (HA). Our results revealed that zinc ion can efficiently induce the dimerization of the HLA-DR1/HA complex. Because the crystal structure of the MAM/HLA-DR1/hemagglutinin complex in the presence of EDTA is nearly identical to the structure of the complex crystallized in the presence of zinc ion, Zn(2+) is evidently not directly involved in the binding between MAM and HLA-DR1. Sedimentation and surface plasmon resonance studies further revealed that MAM binds the HLA-DR1/HA complex with high affinity in a 1:1 stoichiometry, in the absence of Zn(2+). However, in the presence of Zn(2+), a dimerized MAM/HLA-DR1/HA complex can arise through the Zn(2+)-induced DR1 dimer. In the presence of Zn(2+), cooperative binding of MAM to the DR1 dimer was also observed.

SHAP Potentiates the CD44-mediated Leukocyte Adhesion to the Hyaluronan Substratum

CD44-hyaluronan (HA) interaction is involved in diverse physiological and pathological processes. Regulation of interacting avidity is well studied on CD44 but rarely on HA. We discovered a unique covalent modification of HA with a protein, SHAP, that corresponds to the heavy chains of inter-alpha-trypsin inhibitor family molecules circulating in blood. Formation of the SHAP.HA complex is often associated with inflammation, a well known process involving the CD44-HA interaction. We therefore examined the effect of SHAP on the CD44-HA interaction-mediated lymphocyte adhesion. Under both static and flowing conditions, Hut78 cells (CD44-positive) and CD44-transfected Jurkat cells (originally CD44-negative) adhered preferentially to the immobilized SHAP.HA complex than to HA. The enhanced adhesion is exclusively mediated by the CD44-HA interaction, because it was inhibited by HA, but not IalphaI, and was completely abolished by pretreating the cells with anti-CD44 antibodies. SHAP appears to potentiate the interaction by increasing the avidity of HA to CD44 and altering their distribution on cell surfaces. Large amounts of the SHAP.HA complex accumulate in the hyperplastic synovium of rheumatoid arthritis patients. Leukocytes infiltrated to the synovium were strongly positive for HA, SHAP, and CD44 on their surfaces, suggesting a role for the adhesion-enhancing effect of SHAP in pathogenesis.

Quantum chemical analysis explains hemagglutinin peptide–MHC Class II molecule HLA-DRβ1*0101 interactions

We present a new method to explore interactions between peptides and major histocompatibility complex (MHC) molecules using the resultant vector of the three principal multipole terms of the electrostatic field expansion. Being that molecular interactions are driven by electrostatic interactions, we applied quantum chemistry methods to better understand variations in the electrostatic field of the MHC Class II HLA-DRβ1*0101–HA complex. Multipole terms were studied, finding strong alterations of the field in Pocket 1 of this MHC molecule, and weak variations in other pockets, with Pocket 1 ≫ Pocket 4 > Pocket 9 ≈ Pocket 7 > Pocket 6. Variations produced by “ideal” amino acids and by other occupying amino acids were compared. Two types of interactions were found in all pockets: a strong unspecific one ( global interaction) and a weak specific interaction ( differential interaction). Interactions in Pocket 1, the dominant pocket for this allele, are driven mainly by the quadrupole term, confirming the idea that aromatic rings are important in these interactions. Multipolar analysis is in agreement with experimental results, suggesting quantum chemistry methods as an adequate methodology to understand these interactions.

Expression, refolding, crystallization and preliminary crystallographic study of MHC H-2Kk complexed with octapeptides and nonapeptides.

Major histocompatibility complex (MHC) molecules are heterodimeric cell-surface receptors that play a crucial role in the cellular immune response by presenting epitope peptides to T-cell antigen receptors (TCR). Although the structural basis of the peptide-MHC binding mechanism is becoming better understood, it is still difficult to predict a binding mode for an MHC of unknown structure. Therefore, as the first stage of a TCR-MHC interaction study, the crystal structures of the mouse H-2K(k) molecule in complex with both an octapeptide from Influenza A virus and a nonapeptide from simian virus SV40 were solved. Here, the expression, refolding, purification and crystallization of the two complexes are reported. For the H-2K(k)-HA(259-266) complex, crystals were obtained via an extensive screen using a nanodrop-dispensing robot and diffracted to 2.5 A resolution. For the H-2K(k)-SV40(560-568) complex, microscopic needles were initially obtained and their size was improved by macroseeding and a stepwise increase in precipitant concentration. Diffraction data to a resolution of 3.0 A were collected at a synchrotron facility.

Chromium(III) binding abilities of humic acids

The abilities of the humic acids (HA s) to bind Cr(III) were evaluated by a model on the basis of binding between Cr 3+ and CrOH 2+ species and the HA s. This model equation denotes the relationship between the concentration of unbound ([Cr(III)] ub) and bound ([Cr(III)] b) species. The aqueous solution containing Cr(III) and HA was equilibrated, and then [Cr(III)] b was determined by flame atomic absorption spectrometry after a pre-separation with the cation-exchanger, sulphopropyl Sephadex C-25 (C-25), in which the cationic unbound Cr(III) species retained on the C-25 could be calculated by subtracting [Cr(III)] b in the effluent from the total concentration of Cr(III) added initially ([Cr(III)] t). An excellent curve-fitting was obtained in the range of pH 3.2–4.3 by the non-linear least square regression analyses of the proposed model equation to the experimental data set ([Cr(III)] ub, [Cr(III)] b). The calculated conditional binding constants ( K′ Cr 3+ , K′ CrOH 2+ ) and the binding capacities ( N) were as follows: log K′ Cr 3+ , 3.4-4.9; log K′ in 4.9-5.3; N, 0.8-2.4 (mmol g −1 of C), and these values increased with increasing pH. The conditional binding constants of the Cr(III)-HA complex (pH 3.25, I = 0.01) were compared with those of other metal-HA complexes in the literature (pH 3.00, I = 0.01). The log K′ Cr 3+ value was comparable to those of metal ions as Ca 2+, Zn 2+ and the log K′ CrOH 2+ value was comparable to those of Pb 2+, and Cu 2+ and Ni 2+. The N values were larger than those in the case of copper(II) ions. The Cr(III) binding abilities of the peat HA s were also evaluated by the present model. It was found that the N values of the HA s correlated to the carboxylic contents. Comparison of FTIR (Fourier transform infrared) spectra between the protonated HA and Cr(III)-HA complex suggested the existence of Cr(III)-carboxylate binding.

Adsorption of the herbicide glyphosate on a metal-humic acid complex

The interactionof glyphosate with a pure iron-humic acid (Fe-HA) complex was studied by constructing adsorption isotherms at different shaking times. The Freundlich equation better fitted the experimental data than the Langmuir equation. The maximum adsorption values ( k f) showed that glyphosate is adsorbed on Fe-HA complex to an extent that is similar to that found for whole soils and even higher than that shown by other soil minerals. This suggests that HA complexes with polyvalent cations may represent a main binding substrate for glyphosate in soils. The S-type adsorption isotherms found through the application of the Freundlich equation, indicate that at low concentration glyphosate is adsorbed by a ligand exchange mechanism involving the phosphono group and the iron hydration sphere in the HA complex, whereas at higher concentration, more glyphosate may continue to be bound by a hydrogen bonding mechanism, to already sorbed molecules. The high strength of the glyphosate interaction with the Fe-HA complex is demonstrated by the lack of any appreciable desorption for any concentration and any time of contact applied. A rapid increase of the slope of the Freundlich adsorption isotherms at shaking times higher than 48 h is suggestive of some microbial degradation.

Enhanced Solvent Extraction with Water-in-Ok Microemulsions

Abstract This paper examines theoretically the conditions which favor enhanced extraction when a microemulsion phase containing a surfactant and a chelating agent is used as the solvent extraction organic phase. A general thermodynamic model of liquid-liquid distribution in reversed micellar systems is presented. The model treats the reversed micellar aggregates of the surfactant HA as a pseudophase and considers (a) the partition of a chelating extractant (HL) between the continuous organic phase and the reversed micellar pseudophase, (b) transfer of the metal ion Mz+ into the continuous organic phase via reaction with HA monomers, (c) partition of the Mz+-HA complex between the continuous organic phase and the reversed micellar pseudophase, (d) reaction of the Mz+ -HA complex with HL in the reversed micellar pseudophase, and (e) partition of the HL-containing complex between the reversed micellar pseudophase and the continuous organic phase. Quantitative expressions are derived that permit one to identi...

Extraction, complex formation and spectrophotometric determination of iron(III) with 2-carbethoxy-5-hydroxy-1-(4-tolyl)-4-pyridone

The extraction of iron(III) from aqueous HCl, H2SO4, HClO4, HNO3 solutions by 2-carbethoxy-5-hydroxy-1-(4-tolyl)-4-pyridone (HA) dissolved in CHCl3 has been studied. Quantitative extraction of iron(III) is achieved if the concentration of the acids does not exceed 1N. The composition of the iron (III)—HA complex formed in the organic phase was investigated spectrophotometrically, radiometrically and by analysis of the isolated species. In the aqueous phase iron (III) and HA form three different complexes, depending on the initial iron: HA concentration ratio and the pH of the solution. They are the violet FeA2+, the orange-red FeA2 + and the orange-yellow FeA3. The latter is identical with the complex found in the organic phase, which was isolated as a solid crystalline material and characterized by elemental analysis and infrared spectroscopy. A spectrophotometric method for the determination of iron(III) in the aqueous phase and in the chloroform solution, by extraction with HA, is described.

The solvent extraction of hafnium(IV)—VI: Extraction of Hf(IV) by some dialkylphosphoric acids from chloride and nitrate media

The distribution of 175+181Hf(IV) between aqueous hydrochloric or nitric acid and (i) a solution of dibutylphosphoric acid in benzene and chloroform, (ii) di- n-amylphosphoric acid in toluene and (iii) diethylhexyl-and di- n-octylphosphoric acids in n-octane has been studied. In the range of concentrations of Hf used (up to 2 × 10 −6M), Hf is extracted from a hydrochloric acid medium up to C HCI of 3·5 M predominantly as HfClA 3(HA) 2, where HA is the dialkylphosphoric acid. In a medium of nitric acid at C HNO 3 ⩾ 1·5 M, or in one of hydrochloric acid at C HCI ⩾ 4·5 M, the initial ion-exchange reaction mechanism is replaced by an addition type of reaction with the formation of extractable complexes of Hf X 4(HA) y , where X = NO 3, Cl. At higher concentrations of HNO 3, an extractable HNO 3·HA complex is formed which results in a decrease in the distribution ratio of Hf.