Solution properties of polystyrene-block-polybutadiene-block-polystyrene triblock copolymers

The conformational behaviour of polystyrene-block-polybutadiene-block-polystyrenes, ABA-type triblock copolymers, with 50 wt.-% of A blocks were studied by light scattering, viscometric and osmometric methods over a wide range of molecular weight. Unperturbed dimensions were found directly by light scattering in the θ solvent methyl isobutyl ketone and also estimated by extrapolation methods from intrinsic viscosity and osmometric results in toluene, a thermodynamically good solvent. Osmometric and viscometric results showed that the block copolymers form a Gaussian coil in toluene, whereas light scattering results indicated some segregation of blocks for a low-molecular-weight sample in the θ solvent.     

Anti-inflammatory properties of griseofulvin

Anti-inflammatory activity of griseofulvin has been investigated in comparison with indomethacin and flufenamic acid. In vitro, griseofulvin has been proved the most effective of these agents in suppressing the contractions of smooth muscle preparations induced by a variety of proposed mediators of inflammation, i.e. histamine, 5-hydroxytryptamine, bradykinin and prostaglandin E₂. In vivo, griseofulvin was unable to modify dextran oedema but suppressed carrageenin oedema, although its activity was poor when compared to that exhibited by indomethacin and flufenamic acid. When tested in rat pleurisy induced by dextran or homologous serum griseofulvin was able to prevent polymorph migration into the pleural space while mononuclears remained virtually unaffected. In contrast indomethacin and flufenamic acid mainly suppressed mononuclear migration while polymorphs resulted only slightly affected. Similar results have been exhibited by the drugs when tested on mononuclear turnover in pleural cavities from normal rats. Results are discussed in the light of the clinically established ability of griseofulvin to prevent cutaneous inflammatory reactions as well as of its effectiveness in the treatment of several polyarthritic syndromes.     

Anti-inflammatory properties of desloratadine

BACKGROUND: Allergic rhinitis (AR) is associated with robust infiltration of immune cells and mediators that may contribute to clinical manifestations of the disease. OBJECTIVE: To review the complex immune effector mechanisms involved in the allergic response and discuss their effects on the pathophysiological and clinical manifestations of AR. Desloratadine, a novel antihistamine, was used as a probe with the goal of attaining a better understanding of the inflammatory processes underlying the allergic response. METHODS: Data were obtained from abstracts and peer-reviewed journals. The pathophysiology of the allergic response has been extensively studied. This paper presents only data from studies that used desloratadine at physiologically relevant concentrations. RESULTS: Key mediators involved in the allergic response and in pathophysiological and clinical manifestations of the immune response were reviewed. Desloratadine was used as a probe to further elucidate the mechanisms involved during an allergic response. CONCLUSIONS: Some have proposed a link between the pathophysiology of AR and the clinical manifestation of symptoms. Desloratadine, a new-generation antihistamine, has demonstrated anti-inflammatory effects in vitro; indeed, desloratadine is capable of intervening at various points in the immune cascade. Although in vitro results do not necessarily correlate with clinical efficacy, the anti-inflammatory properties of desloratadine may contribute to its efficacy in patients with AR, allergy-induced asthma, and other related allergic conditions. Antihistamines that modulate in the immune system at various stages may optimize treatment of allergic disease.     

Medical-purpose elastic materials based on siloxane rubbers and items made from them.

Vulcanization of the unsaturated siloxane rubbers with silicon hydrides of various structure (organohydrosiloxanes, organohydrosilazanes, organohydrosilanes) was investigated for the purpose of creating biologically-compatible materials with a high complex of medical and engineering properties. The effect of the silicon hydride structure on the vulcanization process and properties of the produced rubbers was identified. The basis sanitary and hygienic indices of rubbers were studied. A wide range of medical-purpose items was manufactured using the developed compounds.     

Dielectric properties of a liquid crystalline siloxane copolymer

An investigation on the molecular dynamics of a liquid crystalline side chain polymer using the dielectric relaxation method on oriented samples in the frequency range of 0,1 to 10 000 kHz is presented. The compound under investigation is a polysiloxane copolymer with two different mesogenic side chains and a phase sequence glassy-smectic A-nematic-isotropic. Three main relaxation processes are found and assigned to the rotation of the side chains around the main chain, the glass transition process coupled with side chain motions, and a local motion in the glassy state, respectively. Evidence is found for a layered arrangement of the polymer main chain in the smectic phase and for a parallel correlation between the transverse components of the dipole moments.     

Anti-inflammatory properties of micropatterned titanium coatings

Prolonged inflammation and reactive oxygen species (ROS) generated around an implanted biosensor are the primary causes of the foreign body response, including encapsulation of biosensor membranes. We have previously demonstrated that TiO2 surfaces reduce ROS. Here we investigated the potential of using the anti-inflammatory properties of TiO2 in the design of biosensor membranes with improved long-term in vivo transport properties. Micropatterned Ti films were sputtered onto quartz surfaces in a series of hexagonally distributed dots with identical coverage area of 23% and dot size ranging from 5 to 100 microm. The antioxidant effect of the surfaces was investigated using a cell-free peroxynitrite donor assay and assays of superoxide released from stimulated surface-adhering neutrophils and macrophages. In all three assays, the amount of ROS was monitored using luminol-amplified chemiluminescence. Patterned surfaces in all experimental models significantly decreased ROS compared to the etched surfaces. In the cell-free experiment, the ROS reduction was only dependent on fractional surface coverage. In the cell experiments, however, a dot-size-dependent ROS reduction was seen, with the largest reduction at the smallest dot-size surfaces. These results indicate that micropatterned surfaces with small dots covering only 23% of the surface area exhibit similar antioxidative effect as fully covered surfaces.     

Anti-inflammatory properties of lipid oxidation products

Oxidative modification of lipids occurs during inflammatory processes and leads to the formation and accumulation of biologically active lipid oxidation products that induce specific cellular reactions. These reactions lead to a modulation of the inflammatory process and may determine the fate and outcome of the body's reaction in acute inflammation during host defense. The processes by which oxidized lipids may play an important role include resolution of inflammation involving apoptosis, chronic inflammatory processes, and innate and adaptive immune responses. The classical view of lipid oxidation products is that they can induce and propagate chronic inflammatory reactions. However, evidence is accumulating that cells and tissues respond towards these oxidatively formed stress signals also by activation of anti-inflammatory processes. These include defense strategies such as (a) induction of signaling pathways leading to the upregulation of anti-inflammatory genes, (b) inhibition of signaling pathways coupled to the expression of proinflammatory genes, and (c) preventing the interaction of proinflammatory bacterial products with host cells. This contribution summarizes recent findings on the anti-inflammatory action of oxidized lipoproteins and lipid oxidation products. We discuss confirmed and suggested mechanisms as well as the (patho)physiological significance of these findings.     

Viscous properties of butadiene/styrene triblock copolymer solutions

Viscosities of dilute and concentrated solutions of a styrene-butadiene-styrene triblock copolymer in solvents of different thermodynamic quality and at different temperatures were studied. In 1,4-dioxane (theta solvent for butadiene blocks) the viscosity derived polymer-polymer interaction parameter has been found to be much smaller than in decalin (theta solvent for styrene blocks) or in tetralin (good solvent for both blocks). The dynamic viscosity and the enthalpy of activation of viscous flow, ΔH, increase much faster for 1,4-dioxane solutions with increasing concentration than those for decalin or tetralin. The different properties of solutions in different solvents are discussed in terms of the physical structure of the systems.     

Anti-inflammatory and immunomodulatory properties of Carica papaya

Chronic inflammation is linked with the generation and progression of various diseases such as cancer, diabetes and atherosclerosis, and anti-inflammatory drugs therefore have the potential to assist in the treatment of these conditions. Carica papaya is a tropical plant that is traditionally used in the treatment of various ailments including inflammatory conditions. A literature search was conducted by using the keywords “papaya”, “anti-inflammatory and inflammation” and “immunomodulation and immune” along with cross-referencing. Both in vitro and in vivo investigation studies were included. This is a review of all studies published since 2000 on the anti-inflammatory activity of papaya extracts and their effects on various immune-inflammatory mediators. Studies on the anti-inflammatory activities of recognized phytochemicals present in papaya are also included. Although in vitro and in vivo studies have shown that papaya extracts and papaya-associated phytochemicals possess anti-inflammatory and immunomodulatory properties, clinical studies are lacking.     

Anti-inflammatory properties of IL-1 in carrageenan-induced paw oedema

To evaluate any inhibitory effect of a single dose of human recombinant interleukin-1 (hrIL-1) on the severity of carrageenan-induced oedema in rats (a commonly used model of acute inflammation), we first injected 0.1 ml of carrageenan (0.2%, 0.5%, or 2%) to induce mild, moderate, or severe inflammation, respectively into the right rear footpad. Then we promptly injected the interleukin (0.02, 0.2, or 2 g) subcutaneously into the flank. The initial rapid increase in volume of the injected paw (within 2 h of the subplantar injection) was independent of the dose of carrageenan, whereas the increase in volume by 6 to 10 h was dose-dependent, All doses of HrIL-1 inhibited the carrageenan-induced swelling at the 6th hour. In the moderate and severe carrageenan-induced oedemas, the higher dose of HrIL-1 induced a delayed inflammation peaking at 10 h instead at 6 h.     

Side-chain liquid-crystalline polymers containing siloxane spacer, 3. Thermal properties of copolymers containing different types of mesogens

Copolymerization of monomers containing the disiloxane unit in the spacer component and linear triple-core mesogens with comonomers containing linear double-core mesogens, or laterally attached triple-core mesogens was carried out radically. The effect of copolymer composition and monomer structure on the mesomorphic properties of the obtained copolymers was investigated in detail. The copolymers with a comonomer content up to 50 mol-%, exhibit an enantiotropic nematic phase, whereas the parent homopolymers containing triple-core mesogens exhibit a smectic phase. The copolymer containing more than 50 mol-% of the comonomer shows no mesophase. The isotropization temperature of the copolymers decreases with increasing comonomer content. However, the glass transition temperature is almost unchanged upon introduction of the comonomer unit. In case of copolymers containing laterally attached mesogens, a smectic phase was observed below the temperature range of the nematic phase. Consequently, the mesophase and the temperature range of the liquid-crystalline state can be controlled by the introduction of the comonomer unit whose parent homopolymer does not exhibit any mesophase.     

Anti-inflammatory and antioxidant properties of Eriobotrya japonica leaves extracts

Background

In the present work we determined phenolic and flavonoids content of Eriobotrya japonica leaves extracts and fractions and their antioxidant and anti-inflammatory properties.

Objectives

To evaluate the inhibition of inflammatory PLA2 and antioxidant effects of extracts and fractions from Eriobotrya japonica leaves

Methods

Antioxidant activity was evaluated with DPPH radical scavenging assay and anti-inflammatory effect of fractions was measured by their inhibition potency on the human pro-inflammatory phospholipase A2 (group IIA).

Results

The EtOH/EtOAc 2:1 extract exhibited a potent inhibition of the hG-IIA with an IC50 values of 8 µg/ml. It also shows an antioxidant activity measured on DPPH with an IC50 of 42 µg/ml. Fractionation shows that CH2Cl2/MeOH 0:1 fraction was the rich one on flavonoids compounds (4.3 mg/g dry weight) and demonstrates a high antioxidant activity with an IC50 of 12 µg/ml. The anti-inflammatory evaluation demonstrates that the same fraction was the best one to inhibit the pro-inflammatory phospholipase A2 group IIA with an IC50 of 4 µg/ml.

Conclusion

Study conducted on Eriobotrya japonica shows that CH2Cl2/MeOH 0:1 fraction inhibits efficiently the hG-IIA phospholipase. which is considered as pro-inflammatory enzyme.     

Viscoelastic properties of some soft lining materials. II--Ageing characteristics.

A non-resonant forced vibration, dynamic mechanical analyser was employed to measure the viscoelastic characteristics of soft lining materials at 1 Hz, after storage in distilled water at mouth temperature for periods up to and including one year. The six commercial products included methacrylate, silicone, and phosphazine based polymers and the one experimental material was a methacrylate. Water sorption of the soft liners, recorded by change in sample mass, ranged from -4.39 to +48.57% and their solubilities from 0.13 to 13.58%, after one year. The heat-cured silicone was the most stable polymer in water in contrast to its autopolymerised counterpart. The excessive water uptake of this latter material resulted in a massive reduction in modulus. At the other extreme one methacrylate with a high plasticiser content hardened substantially after ageing (modulus changed from 5.87 to 72.3 MPa). Changes in loss tangent data were relatively small for all the polymers tested, even for materials with high water uptake. Reduced leaching and/or plasticiser content have led to a more stable generation of soft lining materials.     

Physical and biological properties of a novel siloxane adhesive for soft tissue applications

The aim of this study was to investigate the adhesive properties of an in-house aminopropyltrimethoxysilane-methylenebisacrylamide (APTMS-MBA) siloxane system and compare them with a commercially available adhesive, n-butyl cyanoacrylate (nBCA). The ability of the material to perform as a soft tissue adhesive was established by measuring the physical (bond strength, curing time) and biological (cytotoxicity) properties of the adhesives on cartilage. Complementary physical techniques, X-ray photoelectron spectroscopy, Raman and infrared imaging, enabled the mode of action of the adhesive to the cartilage surface to be determined. Adhesion strength to cartilage was measured using a simple butt joint test after storage in phosphate-buffered saline solution at 37 degrees C for periods up to 1 month. The adhesives were also characterised using two in vitro biological techniques. A live/dead stain assay enabled a measure of the viability of chondrocytes attached to the two adhesives to be made. A water-soluble tetrazolium assay was carried out using two different cell types, human dermal fibroblasts and ovine meniscal chondrocytes, in order to measure material cytotoxicity as a function of both supernatant concentration and time. IR imaging of the surface of cartilage treated with APTMS-MBA siloxane adhesive indicated that the adhesive penetrated the tissue surface marginally compared to nBCA which showed a greater depth of penetration. The curing time and adhesion strength values for APTMS-MBA siloxane and nBCA adhesives were measured to be 60 s/0.23 MPa and 38 min/0.62 MPa, respectively. These materials were found to be significantly stronger than either commercially available fibrin (0.02 MPa) or gelatin resorcinol formaldehyde (GRF) adhesives (0.1 MPa) (P < 0.01). Cell culture experiments revealed that APTMS-MBA siloxane adhesive induced 2% cell death compared to 95% for the nBCA adhesive, which extended to a depth of approximately 100-150 microm into the cartilage surface. The WST-1 assay demonstrated that APTMS-MBA siloxane was significantly less cytotoxic than nBCA adhesive as an undiluted conditioned supernatant (P < 0.001). These results suggest that the APTMS-MBA siloxane may be a useful adhesive for medical applications.     

Tensile properties of suture materials

The tensile properties of three new sutures, two non-absorbable and one absorbable material, have been evaluated and compared with those of polypropylene and nylon sutures. It was found that the five materials differed significantly in their tensile strengths and elastic/plastic deformation characteristics but displayed comparable elongations at failure. All sutures showed a decrease in failure load and elongation at failure when knotted. Most materials showed an increased tensile strength and decreased elongation at failure for smaller suture gauges, and this behaviour is thought to be related to their internal molecular organization.     

Hemostatic properties of glucosamine-based materials

Glucosamine- and N-acetyl glucosamine-containing polymers are being used in an increasing number of biomedical applications, including in products for surface (topical) hemostasis. The studies presented here investigate the relationship between the structure (conformation) and function (activation of hemostasis) of glucosamine-based materials. Several polymer systems were studied, including fibers isolated from a microalgal source containing poly-N-acetyl glucosamine polymers that are organized in a parallel, hydrogen-bonded tertiary structure and can be chemically modified to an antiparallel orientation; and gel formulation derivatives of the microalgal fibers consisting of partially deacetylated (F2 gel) and fully deacetylated (F3 gel) polymers. Comparison of the properties of the poly-N-acetyl glucosamine fiber-derived materials with chitin, chitosan, and commercial chitosan-based products are presented. Several studies were performed with the glucosamine-based materials, including (1) an analysis of the ability of materials to activate platelets and turnover of the intrinsic coagulation cascade, (2) an examination of the viscoelastic properties of mixtures of platelet-rich plasma and the glucosamine-based materials via thromboelastography, and (3) scanning electron microscopic studies to examine the morphology of the glucosamine-based materials. The results presented demonstrate that hemostatic responses to the glucosamine-based materials studied are highly dependent on their chemical nature and tertiary/quaternary structure. The unique natural microalgal fibers were found to have strongly prohemostatic activity compared to the other materials studied.     

Viscoelastic properties of some soft lining materials. I--Effect of temperature

The time dependent, viscoelastic characteristics of a number of dental soft liners (occasionally called resilient liners) were investigated using a dynamic mechanical analyser (DMA). The materials consisted of eight commercial products including methacrylate, silicone and phosphazine-based soft polymers as well as two experimental formulations. The DMA used was of the forced vibrational variety. The test conditions, such as frequency and temperature, were chosen to mimic in use (masticatory) conditions. A wide variety of behaviour was observed and accounted for. This included a seven fold range in the storage modulus (2.79-19.7 MPa) and a 50-fold range in the loss tangent (0.029-1.52) at 37 degrees C and 1 Hz. The materials could generally be divided into either rubbery behaviour with low modulus and loss tangent, i.e. the silicones, or leathery behaviour with both higher modulus and loss tangent, i.e. the methacrylates. A search of the literature did not find a universally preferred set of properties, although a possible link with residual ridge resorption is indicated.     

Anti-inflammatory properties of 4,5-diphenyl-2-oxazolepropionic acid (oxaprozin)

The oxazole, oxaprozin has a spectrum of activity in various in vivo and in vitro, chronic and acute inflammatory models in 3 species indicating that it belongs to the general class of non-steroidal anti-inflammatory agents. Possible advantageous features of oxaprozin over existing nonsteroidal anti-inflammatory agents include relative safety, minimal irritant properties on the gastrointestinal tract, long half-life, and uricosuric properties.