Synthesis of a polymeric 4-N-linked sialoside which inhibits influenza virus hemagglutinin

A multiple sialic acid-bearing polymer 7 has been made in which a novel 4-N-substituted sialoside 5 has been coupled to polyacrylamide. The conjugate 7 has been found to inhibit the agglutination of influenza virus to red blood cells with HAI inhibition constants of around 10(-6) M, based on the sialic acid concentration.

[The dynamics of the healing of experimentally reproduced bone defects filled with different polyacrylamide gel-based compounds]

Time course of healing of standard osseous defects by introduction of polyacrylamide gel (PAG)-based materials was studied in rat experiments. PAG did not prevent the formation of soft-tissue and osseous regenerate in bone defects. Addition of hydroxyapatite, bactericidal agent, and lysozyme to PAG-based composition led in some cases to development of chronic inflammation and giant-cell reaction in osseous wound and to inhibition of the reparative processes.

Photochemically immobilized polymer coatings: effects on protein adsorption, cell adhesion, and leukocyte activation

Amphiphilic chains of 4-benzoylbenzoic acid moieties and polymer were photochemically immobilized onto silicone rubber to ask whether the covalently coupled polymers would passivate the silicone rubber by inhibiting protein adsorption and subsequent cell adhesion and activation. Three groups of polymers were utilized: the hydrophilic synthetic polymers of polyacrylamide, polyethylene glycol, and polyvinylpyrrolidone; the glycosaminoglycan, hyaluronic acid; and poly(glycine-valine-glycine-valine-proline), a polypeptide derived from the sequence of elastin. Each coating variant decreased the adsorption of fibrinogen and immunoglobulin G compared to uncoated silicone rubber. All except the methoxy-polyethylene glycol coating nearly abolished fibroblast growth, but none of the coating variants inhibited monocyte or polymorphonuclear leukocyte adhesion. Interleukin-1beta, interleukin-1 receptor antagonist, and tumor necrosis factor-alpha secretion by leukocytes were not statistically different between any of the coating variants and uncoated silicone rubber. However, the methoxy-polyethylene glycol and elastin-based polypeptide coatings, which supported the highest numbers of adherent monocytes, also elicited the lowest levels of proinflammatory cytokine secretion. When these in vitro data were collectively evaluated, the coating that most effectively passivated silicone rubber was the polypeptide derived from elastin.

[The effect of the microenvironment of the liver tissues on the dynamic resorption of hemostatic resorbable materials and of adhesive compositions]

In experiment there was studied up the cells and tissues reaction on implantation of hemostatic alginate material "Gram-1", "hemostatic gauze" preparation, fibrinous glue composition and sulfoacrylate adhesive glue MK-3.

Influences of 4-meta/MMA-TBB adhesive resin on osteodentinogenesis of transplanted rabbit dental pulp in vivo: immunohistochemical and electronmicroscopic studies

The purpose of this study was to investigate the influence of 4-META/MMA-TBB adhesive resin (4-META resin) on osteodentinogenesis of transplanted pulp in vivo. Dental pulp was obtained from the incisors of adult rabbits. 4-META resin was applied to the pulp tissue, and the pulp tissue with 4-META resin was autotransplanted beneath the renal capsule with the pulp side touching the kidney. Pulp tissue alone was also transplanted as a control. The animals were sacrificed at 3, 7, and 14 days after the experiment, and the specimens were examined morphologically. At 3 days, proliferation of mesenchymal cells was observed, and alkaline phosphatase activity (ALP) and osteocalcin were detected throughout the entire transplanted pulp area. In the experimental case, a thin, highly electron dense zone and a granular layer were observed. Under this layer, only a cell-membrane-like structure, a cell with an unclear nucleus, a nucleus alone, and an organelle-like structure could be seen. Furthermore, an exudative layer with many neutrophils was observed, and apoptotic-body-like structures were also found in some areas. On days 7 and 14 in the control group, osteoblast-like cells had proliferated, and osteodentin formation was initiated throughout the entire transplanted pulp area. In the experimental cases at 7 and 14 days, the entire transplanted area had become osteodentin except for a thin fibrous layer under the 4-META resin. These results suggested that the components of 4-META resin such as MMA and 4-MET (A), which guide the polymerization, might cause degeneration of, but not disturb, the wound healing of the pulp tissue.

Carbomer inhibits tryptic proteolysis of luteinizing hormone-releasing hormone and N-alpha-benzoyl-L-arginine ethyl ester by binding the enzyme

PURPOSE

To determine the mechanism by which Carbomer inhibits the enzymatic activity of trypsin in hydrolysis of N-alpha-benzoyl-L-arginine ethyl ester (BAEE) and luteinizing hormone-releasing hormone (LHRH).

METHODS

Inhibition of enzymatic activity was studied by measuring the formation of metabolites from LHRH and BAEE. Binding of trypsin and substrates to 0.35% (w/v) Carbomer at pH 7.0 was studied by centrifugal filtration. Gel filtration and reverse phase HPLC was used to determine the stability of trypsin.

RESULTS

Carbomer reduced the rate of hydrolysis of BAEE and LHRH by trypsin to 34% and 28% of the control activity, respectively. The rate of metabolite formation for both substrates followed pseudo-zero order kinetics in the presence and absence of carbomer. Binding studies showed that 68% of the trypsin protein and 10% of BAEE was bound to carbomer, but no LHRH was bound. No low molecular weight autolysis products of trypsin could be identified by gel filtration. Reverse phase HPLC analysis of the unbound carbomer-treated-trypsin suggests a number of conformational forms of trypsin. The equilibrium binding capacity was 30 microg of trypsin to 1000 microg of carbomer.

CONCLUSIONS

Decreased hydrolysis of LHRH and BAEE by trypsin in the presence of carbomer is due to enzyme-polymer interaction.

Hemolytic activity of pH-responsive polymer-streptavidin bioconjugates

Drug delivery systems that increase the rate and/or quantity of drug release to the cytoplasm are needed to enhance cytosolic delivery and to circumvent nonproductive cell trafficking routes. We have previously demonstrated that poly(2-ethylacrylic acid) (PEAAc) has pH-dependent hemolytic properties, and more recently, we have found that poly(2-propylacrylic acid) (PPAAc) displays even greater pH-responsive hemolytic activity than PEAAc at the acidic pHs of the early endosome. Thus, these polymers could potentially serve as endosomal releasing agents in immunotoxin therapies. In this paper, we have investigated whether the pH-dependent membrane disruptive activity of PPAAc is retained after binding to a protein. We did this by measuring the hemolytic activity of PPAAc-streptavidin model complexes with different protein to polymer stoichiometries. Biotin was conjugated to amine-terminated PPAAc, which was subsequently bound to streptavidin by biotin complexation. The ability of these samples to disrupt red blood cell membranes was investigated for a range of polymer concentrations, a range of pH values, and two polymer-to-streptavidin ratios of 3:1 and 1:1. The results demonstrate that (a) the PPAAc-streptavidin complex retains the ability to lyse the RBC lipid bilayers at low pHs, such as those existing in endosomes, and (b) the hemolytic ability of the PPAAc-streptavidin complex is similar to that of the free PPAAc.

Acceleration of wound healing with topically applied deoxyribonucleosides

HYPOTHESIS

We hypothesized that a topical mixture of purified deoxyribonucleosides would accelerate wound healing in an open wound model.

DESIGN

Full-thickness 6-mm wounds were made on the ears of young adult rabbits. In some experiments, 2 of the 3 arteries in each ear were divided to induce wound ischemia.

INTERVENTIONS

An equiweight mixture containing all 4 of the major deoxyribonucleosides (deoxyadenosine, deoxycytidine, deoxyguanosine, and thymidine), designated PN105, or other subgroups of deoxyribonucleosides, or vehicle (saline) was applied to wounds on 1 ear every 2 days, with the other ear serving as a control.

MAIN OUTCOME MEASURES

Wound tissue was processed for histological examination 7 days after the initial wounding. Granulation tissue formation and epithelialization were measured in histological cross sections of wounds.

RESULTS

Treatment of wounds with PN105 resulted in a 191% increase in total new granulation tissue (P<.05) and a higher incidence of complete wound reepithelialization (67% vs 37%; P<.05) when compared with controls, and a similar increase under ischemic conditions on day 7. Wound ischemia markedly impairs healing; PN 105 treatment resulted in a 242% increase in the amount of new granulation tissue formed by day 7 in ischemic wounds, relative to the appropriate controls (P<.05). All 4 of the major deoxyribonucleosides were required for optimum activity; mixtures with 3 or 2 were less active or inactive.

CONCLUSIONS

Topically applied deoxyribonucleosides reproducibly accelerate wound healing in normal and ischemic wounds, and to a magnitude equivalent to that of recombinant growth factors such as platelet-derived growth factor, previously studied in this model. In view of their safety, availability, and efficacy, deoxyribonucleosides hold considerable promise for improving healing of chronic wounds.

Flow cytometric study of in vitro neutrophil activation by biomaterials

Neutrophil activation for adherent and nonadherent cells, as measured by flow cytometry, was not strongly dependent on material surface chemistry. We had hypothesized that material-induced neutrophil activation was an important parameter associated with material failure. All materials tested [cellophane, an acrylonitrile copolymer (AN69), Pellethane, nylon, polyethylene terephthalate, low density polyethylene, and polydimethylsiloxane] activated isolated human neutrophils, which were resuspended in plasma or serum, to similar extents based on L-selectin shedding, CD11b upregulation, and stimulation of the oxidative burst after 30-min exposure. Inhibition of complement activation by sCR1 unexpectedly had little effect if any on nonadherent neutrophils. However, neutrophil adhesion, but not the level of activation of the adherent cells, was strongly dependent on complement activation. Pretreatment with albumin did not inhibit adhesion or reduce neutrophil activation, but plasma pretreatment resulted in increased activation for nonadherent and adherent cells. More adhesion and a higher level of activation of adherent cells was observed following pretreatment with fibrinogen, a ligand of CD11b. Taken together these results suggest that upon contact with a material, neutrophil activation may occur though mechanisms that are not mediated by complement. For example, the presence of plasma proteins such as fibrinogen at the interface may trigger activation and the release of other activating agents. Although the material differences are small, the extent of activation may be significant and warrant further study of the mechanism and consequences of that activation.

Release of methyl methacrylate from heat-cured and autopolymerized resins: cytotoxicity testing related to residual monomer

Three heat-cured and three autopolymerized acrylic denture bases with different mixing proportions and/or processing methods were investigated for the amount of residual monomer content and methyl methacrylate (MMA) released into saliva after incubation during the first and second 24 hours after processing. A corresponding range of concentrations of MMA was also used to test for cell cytotoxicity using a culture of human oral fibroblasts. The results showed that the amount of residual monomer was dependent not only on the type of polymerization but also on the amount of liquid in the mixture ratio and the processing method. The acrylic resin that had the lowest residual monomer also released the smallest amount of MMA but resins which have higher residual monomer may not necessarily release higher amounts of MMA. MMA, tested in the same range of concentration as the MMA found leached from acrylic resin in this study, was found to be toxic in the cell culture. Therefore, it is recommended that dentists attempt to reduce the amount of leachable substances before insertion of new dentures. In addition, it is recommended that dentists advise their patients not to wear newly made dentures overnight, as this may cause mucosal irritation from the potential accumulation of leachable substances.

Inhibition of viral adhesion and infection by sialic-acid-conjugated dendritic polymers

Multiple sialic acid (SA) residues conjugated to a linear polyacrylamide backbone are more effective than monomeric SA at inhibiting influenza-induced agglutination of red blood cells. However, "polymeric inhibitors" based on polyacrylamide backbones are cytotoxic. Dendritic polymers offer a nontoxic alternative to polyacrylamide and may provide a variety of potential synthetic inhibitors of influenza virus adhesion due to the wide range of available polymer structures. We evaluated several dendritic polymeric inhibitors, including spheroidal, linear, linear-dendron copolymers, comb-branched, and dendrigraft polymers, for the ability to inhibit virus hemagglutination (HA) and to block infection of mammalian cells in vitro. Four viruses were tested: influenza A H2N2 (selectively propagated two ways), X-31 influenza A H3N2, and sendai. The most potent of the linear and spheroidal inhibitors were 32-256-fold more effective than monomeric SA at inhibiting HA by the H2N2 influenza virus. Linear-dendron copolymers were 1025-8200-fold more effective against H2N2 influenza, X-31 influenza, and sendai viruses. The most effective were the comb-branched and dendrigraft inhibitors, which showed up to 50000-fold increased activity against these viruses. We were able to demonstrate significant (p < 0.001) dose-dependent reduction of influenza infection in mammalian cells by polymeric inhibitors, the first such demonstration for multivalent SA inhibitors. Effective dendrimer polymers were not cytotoxic to mammalian cells at therapeutic levels. Of additional interest, variation in the inhibitory effect was observed with different viruses, suggesting possible differences due to specific growth conditions of virus. SA-conjugated dendritic polymers may provide a new therapeutic modality for viruses that employ SA as their target receptor.

Platelet adhesion and complement activation studies on poly(N-alkyl mono and disubstituted) acrylamide derivatives

Poly(N-alkyl mono and disubstituted) acrylamide derivatives were synthesized from poly(acryloyl chloride) by monomer analogous reaction. The polymers were characterized by FTIR-ATR and GPC. The contact angle measurements were performed to evaluate hydrophobic/hydrophilic characters of these polymers. The N-alkyl substituents changed contact angle between 55 and 75 degrees. In vitro platelet adhesion studies showed that surfaces of poly(N-alkyl substituted) acrylamides are prone to adhere platelets. Platelet spreading was more on poly(N-benzyl-N-ethyl acrylamide) surfaces in comparison to that on poly(N-benzyl-N-propionic acid ethyl ester acrylamide) and poly(N-benzyl acrylamide) surfaces. As a result of modification of amino group with N-alkyl substituents, the activations of C3a and C5a complements were suppressed 9-20% and 5-6% of native poly(acrylamides), respectively.

Polylysine decelerates kinetics of negatively charged gramicidin channels as shown by sensitized photoinactivation

Effect of a cationic polymer, poly(L-lysine), on the kinetic properties of ionic channels formed by neutral gramicidin A (gA) and its negatively charged analogue O-pyromellitylgramicidin (OPg) in a bilayer lipid membrane is studied using a method of sensitized photoinactivation. This newly developed method is based on the analysis of transmembrane current transients induced by a flash in the presence of a photosensitizer. It has been shown previously that the time course of the flash-induced current decrease in most cases follows a single exponential decay with an exponential factor (tau, the characteristic time of photoinactivation) that correlates well with the single-channel lifetime. Addition of polylysine does not affect tau for gA channels, but causes a substantial increase in tau for OPg channels. This effect is reversed by addition of polyacrylic acid. The deceleration of the photoinactivation kinetics is ascribed to electrostatic interaction of polylysine with OPg probably resulting in OPg clustering. The latter can stabilize the channel state by reducing the rotational and lateral mobility of OPg monomers and dimers, and thus increase the single channel lifetime.

Alkyl-esters of polyacrylic acid as vaccine adjuvants

Previously, we demonstrated that polyacrylic acid (PAA) augmented significantly the immune response to inactivated Newcastle disease virus (iNDV) in chickens, but that efficacy was insufficient to replace the water-in-mineral oil (W/O) adjuvant applied for boosting primed animals. Attempting to improve its adjuvanticity, PAA with weight-average molecular weight (Mw) of 450 kDa was grafted with alkyl-chains by esterifying the carboxylic groups with octanol and butanol. The butyl-PAA and octyl-PAA esters obtained varied in degree of esterification between 10% and 92%. Adjuvant activity of water-soluble esters for humoral responses to iNDV was examined in chickens primed previously with iNDV without adjuvant. The alkyl-PAA esters exhibited significantly higher responses than unmodified PAA and titres increased with increasing dose of adjuvant. At doses of 2 mg per animal, octyl- and butyl-PAA esters with a substitution rate of 16% (octyl16-PAA and butyl16-PAA, respectively) gave similar titres as W/O. In aged animals primed with live NDV at early age, butyl16-PAA and W/O elicited comparable antibody responses. Butyl16-PAA was also more effective than PAA in stimulating primary immune responses in mice which was accompanied by stronger local reaction determined by monitoring swelling at the site of injection. Reactogenicity of butyl16-PAA was less than of W/O. We concluded that alkyl-PAA esters are strong adjuvants for primary and secondary responses and that they are promising alternatives to the mineral oil-based adjuvants presently used in various veterinary vaccines.

[The biomedical efficacy of 2 variants of polyacrylamide gel- and hydroxyapatite-based composite materials in the plastic repair of bone defects (experimental morphological research)]

Tissue status at the site of experimental bone defects filled by two compositions based on polyacrylamide gel and hydroxyapatite with (experimental group) and without (controls) lysozyme was studied in rats by the histomorphological method. "Negative" symptoms, such as inflammation, formation of osteocyte-free bone at the interface of the defect, and reduction of red bone marrow were more manifest in the controls than in animals treated with lysozyme. In the test group substitution of composite material for connective tissue structures and bone reparation were much more active and rapid than in the controls. Inflammation and dystrophic changes at the interface of defects were less pronounced and gradually resolved.

Effects of pharmacological fiber supplements on levothyroxine absorption

To determine the effect of pharmacological fiber supplements, we measured levothyroxine (LT4) absorption without and with simultaneous ingestion of either calcium polycarbophil or psyllium hydrophilic mucilloid. Serum thyroxine (T4) levels in 8 volunteers were measured following ingestion of 600 microg of LT4 on 3 separate occasions at 4-week intervals: (1) LT4 alone; (2) LT4 together with 1000 mg polycarbophil; and (3) LT4 together with 3.4 g psyllium. The amount of absorbed LT4 was calculated as the incremental rise in serum T4 level during the first 6 hours multiplied by the volume of distribution for the hormone, and expressed as a percentage of the dose administered. Absorption of LT4 alone averaged 89% (95% confidence interval [CI]: 75%-104%), occurring at a median of 180 minutes. After simultaneous ingestion of calcium polycarbophil, LT4 absorption was 86% (95% CI: 74%-97%), occurring at 180 minutes. With simultaneous ingestion of psyllium and LT4, the absorption was 80% (95% CI: 64%-95%), occurring at 240 minutes. In summary, neither calcium polycarbophil nor psyllium hydrophilic mucilloid are likely to cause malabsorption of LT4 that could be detected by these methods.

Effects of dentin bonding agents on macrophage mitochondrial activity

Dentin bonding agents (DBA) have been considered for use as root-end fillings. Previous studies have documented the release of DBA components in vivo and in vitro, but the biological implications are not clear. The macrophage is important in wound healing, and likely to be important in any inflammatory response. Therefore, this study determined the concentrations of the components of DBAs that suppress the mitochondrial activity of human macrophages in vitro. THP-1 macrophages were cultured in the presence of four DBA components (2-hydroxyethyl methacrylate (HEMA), 4-methacryloxyethyl trimellitate anhydride (4-META), bisphenol-glycidylmethacrylate (Bis-GMA), and urethane dimethacrylate (UDMA)) at various concentrations and for varying durations. Residual effects were also measured after the resins were removed. Controls received only the vehicle solution, ethanol or water. THP-1 mitochondrial activity was estimated using the MTT assay, and the 50% toxicity concentrations (TC50) were determined graphically. Resin components suppressed the mitochondrial activity of macrophages at different concentrations (TC50 values for HEMA (10,000 mumol/L), 4-META (3,800 mumol/L), Bis-GMA (130 mumol/L), and UDMA (110 mumol/L) at 24 h, and the effect was time-dependent. Residual effects were observed for all resins.

Biomolecular modification of p(AAm-co-EG/AA) IPNs supports osteoblast adhesion and phenotypic expression

Interpenetrating polymer networks (IPNs) were designed to resist materials fouling caused by non-specific protein adsorption, and indiscriminate cell or bacterial adhesion. These IPNs were thin adherent films (approximately 20 nm) comprised of acrylamide (AAm), ethylene glycol (EG), and acrylic acid (AA) grafted to either silicon waters or quartz substrates via photoinitiated free radical polymerization. These networks were further modified to promote specific cell adhesion by tethering bioactive groups such as peptides that mimic cell-binding domains found on extracellular matrix molecules. As a specific example of biomolecular surface engineering, peptides from the cell-binding domain of bone sialoprotein were tethered to a p(AAm-co-EG/AA) IPN to control cell behavior at the surface. The networks were characterized by contact angle measurements, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy to convey information on IPN wettability, thickness, and chemistry. The surface characterization data supported the theory that the PEG/AA layer formed an IPN with the underlying p(AAm) network, and after graft modification of this IPN with diamino PEG (PEG(NH2)2), the PEG(NH2)2 chains were enriched at the surface. Rat calvarial osteoblasts attached to Arg-Gly-Asp (RGD) modified IPNs at levels significantly greater than on clean quartz, Arg-Gly-Glu (RGE) modified, or the PEG(NH2)2 modified IPN, with or without serum in the media. Cells maintained in media containing 15% fetal bovine serum (FBS) proliferated, exhibited nodule formation, and generated sheets of mineralized extracellular matrix (ECM) with the addition on beta-glycerophosphate to the media. Cell adhesion and mineralized ECM formation were specifically dependent on the peptide sequence present at the surface.

Minimized platelet interaction with poly(2-hydroxyethyl methacrylate-block-4-bis(trimethylsilyl)methylstyrene) hydrogel showing anomalously high free water content

Novel hydrophilic-hydrophobic block copolymers - poly(2-hydroxyethyl methacrylate-block-4-bis(trimethylsilyl)methylstyrene) (poly(HEMA-block-BSMS) or BH polymer) - were prepared as materials potentially useful for blood-contacting devices. Among the BH(X) series including poly(HEMA) itself, platelet adhesion and activation are minimum on the surface of BH(10), the block copolymer composed of 10 mol% of the hydrophobic segment. The unique physicochemical characteristics of BH(10) such as the high free water content and the increased mobility of PHEMA segments seem to play an important role in the prevention of platelet adhesion and activation. The water content of BH(10) was twice that of poly(HEMA) itself, even in the presence of 10 mol% of the hydrophobic moiety [poly(BSMS)]. Further, an anomalous increase in free water content was observed for the BH(10) sample measured by DSC. The glass transition temperature of BH(10) in the dry state was determined to be c. 10 degrees C, which was much lower than that observed for each of the homopolymers (c.f.: Tg [poly(HEMA)] = 70 degrees C; Tg [poly(BSMS)] = 160 degrees C), suggesting an increased mobility of tethered PHEMA segments in the BH(10) film.

Clinical, radiographic and histological observations of the radicular pulp following "feracrylum" pulpotomy

The purpose of this study was to assess the pulpal response following application of 1% Feracrylum (Hemolok) to arrest hemorrhage during pulpotomy procedure on 26 sound primary molars. They were filled with ZnOE cement and later restored with silver amalgam. The teeth were followed for clinical, radiographic and later histological success for various intervals of time up to 5 months. Asymptomatic clinical and radiological findings and histological evidence of healing in the form of reparative dentin and fibrous tissue formation the deeper zones of the radicular pulp was observed. The hemostatic and non-toxic nature of feracrylum makes it a promising medicament for pulpotomy procedures.

Saccharide-assisted delivery of cytotoxic liposomes to human malignant cells

The overexpression of lectins by malignant cells was applied for in vitro targeting of liposomes equipped with a saccharide vector and loaded in the lipid phase with a lipid derivative of anticancer agent sarcolysine. The lectin specificity of human leukemia HL-60 and human lung adenocarcinoma ACL cells was revealed by tests with fluorescein-labeled sugar probes. With the help of fluorescent lipid dye it was shown that active saccharide ligands increased the level of the vectored liposome binding to malignant cells by 50-80% as compared to liposomes without vector or with inactive one. The degree of liposome/cell membrane fusion was monitored fluorometrically and was shown to be complete and independent of the vectors. The targeted drug-loaded liposomes had the cytotoxic activity 2-4 times higher as compared to the vector-free ones.

In vivo and in vitro study of fungal presence and growth on three tissue conditioning materials on implant supported complete denture wearers

In this study three type of tissue conditioning materials were used in vitro and in vivo to investigate the presence and growth of Candida albicans, considered to be the pathogenic member of the genus. In vitro test results of different tissue conditioners showed that they have a tendency to have an inhibiting effect on C. albicans at the third day of incubation. For the in vivo tests tissue conditioners were placed in existing maxillary prosthesis of 21 patients who had been treated with endosseous dental implants (seven in each group). The results showed that yeast forms were observed after 3 days in two patients' dentures which were relined with Fitt. Yeasts forms were also seen in three patients' dentures after 6 days, two of them relined with Fixo-gel and the other one relined with Visco-gel. The hyphal form of Candida was seen in four patients' dentures, relined with Fitt, and also in three patients' dentures, relined with Fixo-gel and Visco-gel.