Improved corrosion resistance of commercially pure magnesium after its modification by plasma electrolytic oxidation with organic additives.

The optimal mechanical properties render magnesium widely used in industrial and biomedical applications. However, magnesium is highly reactive and unstable in aqueous solutions, which can be modulated to increase stability of reactive metals that include the use of alloys or by altering the surface with coatings. Plasma electrolytic oxidation is an efficient and tuneable method to apply a surface coating. By varying the plasma electrolytic oxidation parameters voltage, current density, time and (additives in the) electrolytic solution, the morphology, composition and surface energy of surface coatings are set. In the present study, we evaluated the influence on surface coatings of two solute additives, i.e. hexamethylenetetramine and mannitol, to base solutes silicate and potassium hydroxide. Results from in vitro studies in NaCl demonstrated an improvement in the corrosion resistance. In addition, coatings were obtained by a two-step anodization procedure, firstly anodizing in an electrolyte solution containing sodium fluoride and secondly in an electrolyte solution with hexamethylenetetramine and mannitol, respectively. Results showed that the first layer acts as a protective layer which improves the corrosion resistance in comparison with the samples with a single anodizing step. In conclusion, these coatings are promising candidates to be used in biomedical applications in particular because the components are non-toxic for the body and the rate of degradation of the surface coating is lower than that of pure magnesium.

Cytotoxicity, haemolymphatic parameters, and oxidative stress following exposure to sub-lethal concentrations of quaternium-15 in Mytilus galloprovincialis.

The presence of a xenobiotic in the environment can often represent a risk for living organisms. Quaternium-15, a preservative, is one of the most used substances and is added to several cosmetics and other industrial products. For this reason,kwowing the bio-indicator of the marine environment, the toxicological effects potentially elicited by this preservative on the marine invertebrate Mytilus galloprovincialis were studied. The results of this work confirm that quaternium-15, used at 0.1 and 1mg/l concentrations, while metabolized in M. galloprovincialis, causes a decrease in cellular viability, and remarkable changes to the defense and antioxidant system. In fact, haemocyte viability is dramatically reduced, and haemolymphatic parameter measurements indicate a stress on the animal. Moreover, an increase in radical species production, in Thiobarbituric Acid Reactive Species (TBARS) concentration, and in the Heat Shock Protein 70 amount, were observed in hepatopancreas. These changes suggest that the antioxidant systems are activated to overwhelm the oxidative damage induced by quaternium-15. Quaternium-15 jeopardizes both the defense and antioxidant systems. These results provide essential information with the biological fate of quaternium-15 in aquatic organisms, and confirm that biomarkers represent an important tool for modern environmental assessments as they can help with the prediction of pollutants involved in the monitoring program.

Evaluation of Functionality and Biological Responses of Mytilus galloprovincialis after Exposure to Quaternium-15 (Methenamine 3-Chloroallylochloride).

Although the irritant effects of quaternium-15 have been established, little is known about the toxicological consequences induced by this xenobiotic on aquatic invertebrates. The present article reports toxicological, histological and physiological effects of quaternium-15 following the exposure of Mytilus galloprovincialis for 18 days at three different concentrations (0.1, 1.0 and 2.0 mg/L). The results demonstrate that at higher concentrations histological damages to M. galloprovincialis gills occur, like melanosis, light exfoliations, increase of mucus production and infiltrative inflammation. In addition digestive gland cells of M. galloprovincialis, were not able to perform the regulation volume decrease (RVD) owing to osmotic stress following the exposure to the preservative. Overall, this first study on quaternium-15 highlights that it can jeopardize both the morphology and vital physiological processes in marine invertebrates, depending on the duration of exposure and the concentration of the preservative, indicating that further studies are necessary to increase our knowledge about the effects of this substance, commonly added to our products of daily use.

Patch testing for allergic contact dermatitis to cigarettes: smoked/unsmoked components and formaldehyde factors.

A patient with hand dermatitis reported that switching her smoking hand resulted in reduced symptoms. When allergy to cigarettes is suspected the literature supports standard allergy testing as well as testing the individual components of cigarettes. Initial standard patch testing revealed an allergy to formaldehyde and the formaldehyde releasing agent, quaternium-15. The patient did not react to her usual roll-your-own cigarette components but reacted to the smoked filter paper of a particular brand of cigarette she frequently borrowed from a friend. Possible explanations include either a variation of ingredients between cigarettes that alters the formaldehyde concentration or another unidentified allergen in the branded cigarette causing allergic contact dermatitis.

Final report of the amended safety assessment of Quaternium-15 as used in cosmetics.

Quaternium-15 is an antimicrobial agent used in cosmetics as a cosmetic preservative and antistatic agent. Little systemic toxicity was reported in most single-dose or repeated-dose animal studies. Quaternium-15 was an oral teratogen, but not a dermal teratogen, in rats at doses that exceeded the expected cumulative exposure from cosmetics. The frequency of sensitization increased in North America but not in Europe, where Quaternium-15 is used less often. In almost all animal and human studies, Quaternium-15 at 0.2% was not a sensitizer. The weight of evidence suggested that a 0.2% concentration is not a sensitizer and that cosmetic products containing Quaternium-15 up to that level are safe.

[Hexa-sabbath. Foreign matter and vital substances, experts and the critical consumer in the FRG during the 1950s and 1960s]. / Hexa-Sabbat. Fremdstoffe und Vitalstoffe, Experten und der kritische Verbraucher in der BRD der 1950er und 1960er Jahre.

In the late Fifties and early Sixties the regulation of food additives represented a remarkable turning point in German consumer politics, establishing a debate about decision making and policy advice, altering the discourse of purity and contamination, and inaugurating a new political actor, the organized critical consumer. The amendment of the Food Law in December 1958 functioned as a negotiation process between representatives of science, industry and the state, which was institutionalized in the Senate Commissions of the German Research Foundation. While these Commissions for preservatives, foreign matter and colorants worked behind closed doors, a public discourse about the "toxic condition" of modern life and the negative role of the pharmaceutical and chemical industry gained strength. The debate about the admission of hexamethylenetetramine (hexa) took part at a crucial moment. Hexa was used as a preservative in the fish industry. But its anti microbial effectiveness was caused by the decomposition of hexa to formaldehyde. Despite the commission's verdict against hexa, the lobbying activities of the industry granted it a reprieve. In the media, the case of hexa was seen as a touchstone for the capacity of negotiated decision making and the ability of rational scientists to resist the demands of industry. Finally, in 1963 it was the new political actor of the organized critical consumer, heir and successor to the housewife federations as well as to "purists" advocating life reform, who, supported by the media, enforced the prohibition of hexa as a preservative.

New linear polyamine derivatives in spider venoms.

Linear free polyamines were characterized in the venom of the spiders Agelenopsis aperta, Hololena curta, and Paracoelotes birulai by RP-HPLC coupled to mass spectrometry. The several linear polyamines found were tetramine, pentamine, and hexamine derivatives. Some of these natural products were identified as N-hydroxylated, guanidylated, or acetylated compounds. In addition, the biosynthetical pathway leading to the formation of acylpolyamines in spider venoms is discussed.

Cytotoxicity of resin-, zinc oxide-eugenol-, and calcium hydroxide-based root canal sealers on human periodontal ligament cells and permanent V79 cells.

AIM: The purpose of this study was to determine the cytotoxicity of three different types of root canal sealer on human periodontal ligament (PDL) cells and a permanent hamster cell line (V79 cells). METHODOLOGY: Set specimens from two resin based sealers (AH26 and AHPlus), three zinc oxide-eugenol-based sealers (Canals, Endomethasone and N2) and one calcium hydroxide-based sealer (Sealapex) were eluted with culture medium for 1, 2, 3 and 7 days. Cytotoxicity was judged using tetrazolium bromide reduction assay on human primary PDL cells and V79 cells derived from a Chinese hamster. RESULTS: The results showed that elutes from resin-based, zinc oxide-eugenol-based, and calcium hydroxide-based sealers were cytotoxic to primary human PDL cultures and V79 cells. Calcium hydroxide-based sealer was the least toxic sealer amongst the chemicals tested in both cultures. The cytotoxic response decreased in an order of N2 > Endomethasone > AH26 > AHplus > Canals > Sealapex. CONCLUSIONS: The sensitivity of toxicity depended on the materials tested and the cell culture system used. Thus, the use of both permanent and primary cells is recommended for screening of the cytotoxic effects of root canal sealers. In addition, the results confirmed that root canal sealers constantly dissolve when exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions. Use of calcium hydroxide-based material as a root canal sealer initially may result in a more favourable response to periradicular tissues.

The histological effects of four endodontic sealers implanted in the oral mucosa: submucous injection versus implant in polyethylene tubes.

AIM: The aim of this study was to evaluate pigmentation and tissue response to four endodontic sealers placed in the oral mucosa of rabbits by either submucous injection or implant in polyethylene tubes. METHODOLOGY: Thirty white New Zealand rabbits were divided randomly into two groups of eight for N-Rickert and AH-26, and two groups of seven for Fillcanal and Sealer 2 6. On the right side of the filter, corresponding to the gingivo-labial sulcus in humans, the sealer was injected; on the left side the sealer was placed within a polyethylene tube and implanted. Direct clinical observations were made at 30, 60 and 90 days. The animals were then sacrificed for histological analysis. RESULTS: After 60 days of observation N-Rickert and AH-26 produced tattoos that became larger by 90 days. Submucous injection produced larger and more numerous pigmentation, when compared to implant in polyethylene tubes. N-Rickert sealer displayed larger and more numerous tattoos when compared to AH-26. Histological analysis showed no differences between the two methods of implantation. All sealers elicited some kind of inflammatory response; the most irritant was Fillcanal, followed by N-Rickert and AH-26. Sealer 26 elicited a mild reaction only. CONCLUSIONS: Under the conditions of this study there was no relationship between the method of implantation and the tissue response; the silver-containing sealers produced pigmentation, and the concentration of silver influenced the quantity and size of the tattoos. The sealers elicited various responses when in direct contact with the surrounding tissues: the calcium hydroxide-containing sealer had enhanced healing when compared to the other sealers.

Evaluation of the genotoxicity of zinc oxide eugenol-based, calcium hydroxide-based, and epoxy resin-based root canal sealers by comet assay.

Three main types of root canal sealer are currently commonly used in pulp treatment: zinc oxide eugenol-based, calcium hydroxide-based, and epoxy resin-based sealers. In the present study, the genotoxicity of sealer on oral carcinoma cells was evaluated by single-cell gel electrophoresis assay (comet assay). The whole length of the comet and the diameter of the head were measured using an image analysis system. The results were analyzed by one-way analysis of variance to compare the various means. The zinc oxide eugenol-based sealers (Canals, Canals-N, and Tubilseal) did not always cause a dose-dependent increase in genotoxicity. The resin-based sealers (Topseal, AH 26, and AH Plus) caused a dose-dependent increase in genotoxicity, but no such effect was seen with the calcium hydroxide-based sealer (Sealapex). The highest level of DNA damage was induced by the resin-based sealers.

Cytotoxic effect of four root filling materials.

The aim of this study was to evaluate the cytotoxic effect of four root canal sealers: AH26, AH Plus, Diaket and Apexit. In the experiment two cell lines, human cervical carcinoma (HeLa) cells and mouse skin fibroblasts (L929), were used. Under aseptic conditions, the sealers were prepared according to the manufacturers' directions, and 0.01 mL of each material was placed in a 24-well plate. The sealers were covered with cell suspension. The cytotoxicity was estimated by determining the number of viable cells by a light microscope, as well as the total number of cells 24 h, 48 h and 120 h after the treatment with mentioned materials. The results obtained in this study showed the high cytotoxcity of the new AH Plus root canal sealer, which was shown to be equally or more toxic to the standard AH26 and Diaket materials. Apexit was the least toxic sealer.

An in vitro study of the cytotoxicity of two root canal sealers.

The purpose of this in vitro study was to determine the cytotoxicity of two root canal sealing materials (AH26 and AH-Plus). This cytotoxicity test (agar diffusion test) was conducted based on the procedures described in the International Organization for Standardization. The biological reactivity of a mammalian monolayer, L929 mouse fibroblast cells, in response to the tested agents was determined. After the 48-h observation period, the cell cultures exposed to the test articles discs for AH26 and AH-Plus exhibited severe reactivity (grade 4). The positive control article exhibited moderate reactivity (grade 3). No signs of reactivity (grade 0) were noted for the negative control article or the negative control discs. The tested samples of AH26 and AH-Plus are considered cytotoxic and do not meet the requirement of the agar diffusion test. Similar cytotoxicity results have been found in the literature for AH26 and other root canal sealing cements.

In vitro cytotoxicity of a new epoxy resin root canal sealer.

The cytotoxic effects of a new epoxy resin-based root canal sealer (AH-plus), together with those of two other commonly used endodontic sealers (AH26 and zinc oxide-eugenol), have been studied in vitro on a culture of human gingival fibroblasts. Cytotoxicity was assessed by direct incubation of sealers' extracts with the cultured fibroblasts at different time intervals. Morphological and cytotoxic effects of the sealers were evaluated microscopically and spectrophotometrically using the neutral red cytotoxicity assay. Our results demonstrated that the cytotoxic effects induced by zinc oxide-eugenol were detectable as early as 1 hr after mixing and remained at a high level until completion of the experiment (5 wk). AH26, however, induced early cytotoxic effects that lasted for 1 wk, followed by a substantial reduction in cytotoxicity. Cytotoxicity of the AH-plus was confined to the early period of experiment and was no longer detectable after 4 hr of mixing. Comparison between the results obtained for each sealer revealed significant differences at particular time intervals. Our findings suggest the potential advantage of this sealer over the other two sealers.

Lactate dehydrogenase leakage of hepatocytes with AH26 and AH Plus sealer treatments.

Numerous root canals filling materials are available in the field of dentistry, based on various formulas that contain a variety of different and partly mutagenic components, such as epoxy resin sealers, Ca(OH)2-based materials, and zinc oxide-eugenol cements. AH Plus root canal sealer will not release formaldehyde according to the manufacturer, although AH26 does. The purpose of this study was to analyze the leakage of lactate dehydrogenase (LDH) from rat hepatocytes after treatment with AH26 and AH Plus root canal sealers in vitro. Hepatocytes from male Sprague-Dawley rats were used to test the cytotoxicity of AH26 and AH Plus. The root canal sealers were mixed and then dissolved in the dimethyl sulfoxide to final concentrations of 0.01%, 0.04%, and 0.1% (wt/vol), with a dimethyl sulfoxide concentration of < 0.05%. Dosage-dependent and time-dependent lactate dehydrogenase leakage values were measured and tested by one-way ANOVA. The results showed that both AH26 and AH Plus are toxic to rat hepatocytes. At a low concentration, AH26 had a higher toxicity than AH Plus to rat hepatocytes.

Cytotoxic and mutagenic potencies of various root canal filling materials in eukaryotic and prokaryotic cells in vitro.

Cytotoxic and mutagenic effects of root canal filling cements of various chemical composition were determined in vitro. Materials set for 24 h and 1 wk were eluted for 24 h in cell culture medium (cytotoxicity testing) and dimethyl sulfoxide or physiological saline (mutagenicity testing). The differences between cytotoxic potencies of eluates of the endodontic materials on L-929 cells were quantified colorimetrically (MTT test). Eluates of Traitement SPAD were about 5- to 30-fold more toxic than silver-free AH26, Tubli-Seal, CRCS, and Endomethsone N. The rank order of the toxic effects depended on the setting time of mixed materials. Dimethyl sulfoxide and saline eluates of Traitement SPAD, Tubli-Seal, Endomethasone N, CRCS, and Ketac-Endo were not mutagenic in the Ames test. Both eluates of silver-free AH26 set for 24 h were weakly mutagenic in Salmonella typhimurium TA100. Weak mutagenicity of saline eluates of the material was also observed in TA97a and TA102. These results point to the possibility that mixed silver-free AH26 might contain small amounts of two mutagenic substances: bisphenol A diglycidyl ether and formaldehyde.

Cytotoxicity of three resin-based root canal sealers: an in vitro evaluation.

The cytotoxicity of three resin-based root canal sealers (AH26, AH-Plus, Topseal) was evaluated in vitro. The experiments included two cell lines, L929 mouse skin fibroblasts and RPC-C2A rat pulp cells. The cytotoxicity was assessed by sulforodamine B (SRB) colorimetric assay and hemocytometer viable cell counting after 24- and 48-h exposure. AH26 had a severe cytotoxic effect whilst Topseal and AH-Plus showed a markedly lower toxic influence on the cells during the experimental period.

Cytotoxicity of endodontic materials.

An in vitro cell culture model of human gingival fibroblasts and L-929 cells was used to measure the cytotoxicity of currently used root canal sealers Endomet, CRCS, and AH26 and root-end filling materials Amalgam, Gallium GF2, Ketac Silver, mineral trioxide aggregate (MTA), and Super-EBA. Cytotoxic effects were assessed using the MTT assay for mitochondrial enzyme activity and the CV assay for cell numbers. Using inserts culture and L-929 fibroblasts. All-Bond-2 was also evaluated. The statistical analysis of results showed that CRCS was the least cytotoxic sealer followed by Endomet and AH26. Among root-end filling materials, MTA was not cytotoxic; Gallium GF2 displayed little cytotoxicity; and Ketac Silver, Super-EBA, and Amalgam showed higher levels of cytotoxicity. All Bond-2 also displayed a high degree of cytotoxicity. CRCS was the best root canal sealer and MTA the best root-end filling material. The outcome was favorable also for Gallium GF2 as a retrofilling material.

Effects of root canal sealers on immunocompetent cells in vitro and in vivo.

Over the years of testing biocompatibility of endodontic filling materials, little attention has been paid to the potential adverse influences on the function of the immune system. Therefore, the purpose of this study was to investigate the extent to which extractable components of some commonly used root canal sealing materials (ERCS) may interfere with immunocompetent cells in vitro. The potential of these materials to cause delayed-type hypersensitivity (DTH) was also addressed in a rat model system. Extractable components were drawn in cell culture medium from freshly mixed or set material of AH 26. Grossman's sealer, Endomethasone, and Apexit. In-vitro assays included either spleen cells or rat pulp tissue cells that were released following enzymatic digestion with collagenase. Purified T cells for the pulpal cell assay were obtained from rat mesenteric lymph nodes. The effect of ERCS on the proliferation of concanavalin A (con A) stimulated spleen cell was measured by 3H-thymidine incorporation. Pulpal accessory cell function was monitored by the capacity of pulpal cells, pretreated with components of ERCS, to provide signals to con A stimulated T cells. DTH was tested after subcutaneous implantation of root canal sealers (RCS) in rats and challenge by ear injection. Pretreatment of pulpal cells with low dilutions of eluates from extracted AH 26 and Endomethasone resulted in a strong reduction of the T cell proliferation rate. The effect was considerably reduced (P < 0.01) when extracts of the solid material were employed. Extracts of Grossmans' sealer and Apexit affected T cell proliferation only to a limited extent in the pulpal cell assay. In general, assays on spleen cells showed a similar profile, although increased cell division was induced by Grossman's sealer at high eluate dilutions and a concentration-dependent decrease of cell division at lower concentrations of this material. ERCS evoked both immunosuppression and, in some instances, immunostimulation, but they did not release DTH.