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1.
Regul Toxicol Pharmacol ; 133: 105222, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35817209

RESUMO

The European Union restricted the amount of hexavalent chromium (Cr(VI)) in leather in 2015, but skin allergy cases due to Cr-tanned leather are not declining. Standardized extraction methods have been criticized to both over- and underestimate the expected amount of bioavailable Cr(VI) in leather. This study aims to evaluate the ability of four extraction solutions to reduce or preserve Cr(VI): artificial sweat solutions (ASWs) of pH 4.7, 6.5, and 8.0, and phosphate buffer (PB) of pH 8.0. This was investigated by incubating each solution with added Cr(VI) as a function of time, and then measuring the recovered Cr(VI). All solutions, especially PB, preserved Cr(VI) for 24 h. These solutions were also pre-exposed to Cr-free vegetable-tanned leather (VTL) before incubation with Cr(VI). Released vegetable tannin species strongly reduced Cr(VI), with up to 4000 µg/L added Cr(VI) reduced in all solutions after 24 h. However, after 1 h, Cr(VI) was still detectable in extraction solutions at pH 6.5 and above. The reduction of Cr(VI) in relevant extraction solutions is hence a process dependent on time, pH, and the presence of co-released leather species. All extraction solutions, but least PB, have the potential to underestimate any Cr(VI) present on the surface of leather.


Assuntos
Dermatite Alérgica de Contato , Curtume , Cromo , Humanos , Indicadores e Reagentes , Suor/química
2.
Toxicol In Vitro ; 76: 105232, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34365006

RESUMO

Skin permeation and distribution of three of the most common skin sensitizers was investigated using a previously developed animal-free exposure method combined with imaging mass spectrometry. Nickel, cobalt, and chromium (III) salts were dissolved in a buffer and exposed to human skin ex vivo, to be analyzed using time of flight secondary ion mass spectrometry (ToF-SIMS). Our findings demonstrate that metal haptens mainly accumulated in the stratum corneum, however all three metal sensitizers could also be detected in the epidermis. Cobalt and chromium (III) species penetrated into the epidermis to a larger extent than nickel species. The degree of penetration into the epidermis is suggested to be affected by the sensitization potency of the metal salts, as well as their speciation, i.e. the amount of the respective metal present in the solution as bioaccessible and solubilised ions. Our method provided permeation profiles in human skin for known sensitizers, on a level of detail that is not possible to achieve by other means. The findings show that the permeation profiles are different, despite these sensitizers being all metal ions and common causes of contact allergy. Studying skin uptake by only considering penetration through the skin might therefore not give accurate results.


Assuntos
Cloretos/farmacologia , Compostos de Cromo/farmacologia , Cobalto/farmacologia , Haptenos/farmacologia , Níquel/farmacologia , Pele/metabolismo , Feminino , Humanos , Técnicas In Vitro , Espectrometria de Massas , Pele/diagnóstico por imagem , Absorção Cutânea
3.
Arch Toxicol ; 95(9): 2961-2975, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34287684

RESUMO

Welders are daily exposed to various levels of welding fumes containing several metals. This exposure can lead to an increased risk for different health effects which serves as a driving force to develop new methods that generate less toxic fumes. The aim of this study was to explore the role of released metals for welding particle-induced toxicity and to test the hypothesis that a reduction of Cr(VI) in welding fumes results in less toxicity by comparing the welding fume particles of optimized Cr(VI)-reduced flux-cored wires (FCWs) to standard FCWs. The welding particles were thoroughly characterized, and toxicity (cell viability, DNA damage and inflammation) was assessed following exposure to welding particles as well as their released metal fraction using cultured human bronchial epithelial cells (HBEC-3kt, 5-100 µg/mL) and human monocyte-derived macrophages (THP-1, 10-50 µg/mL). The results showed that all Cr was released as Cr(VI) for welding particles generated using standard FCWs whereas only minor levels (< 3% of total Cr) were released from the newly developed FCWs. Furthermore, the new FCWs were considerably less cytotoxic and did not cause any DNA damage in the doses tested. For the standard FCWs, the Cr(VI) released in cell media seemed to explain a large part of the cytotoxicity and DNA damage. In contrast, all particles caused rather similar inflammatory effects suggesting different underlying mechanisms. Taken together, this study suggests a potential benefit of substituting standard FCWs with Cr(VI)-reduced wires to achieve less toxic welding fumes and thus reduced risks for welders.


Assuntos
Poluentes Ocupacionais do Ar/toxicidade , Cromo/toxicidade , Aço Inoxidável/toxicidade , Soldagem , Poluentes Ocupacionais do Ar/análise , Brônquios/citologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cromo/análise , Cromo/química , Dano ao DNA/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Humanos , Inflamação/induzido quimicamente , Inflamação/patologia , Macrófagos/efeitos dos fármacos , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/análise , Aço Inoxidável/análise , Células THP-1
4.
Contact Dermatitis ; 85(3): 340-353, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34089526

RESUMO

BACKGROUND: Tattoo inks have been reported to elicit allergic contact dermatitis. OBJECTIVES: To investigate the labels and the contents of metals and pigments in tattoo inks, considering restrictions within the European Union. METHODS: Seventy-three tattoo inks currently available on the market, either bought or donated (already used), were investigated for trace metals and pigments by inductively coupled plasma mass spectrometry and by matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry. RESULTS: Ninety-three percent of the bought tattoo inks violated European, legal requirements on labeling. Fifty percent of the tattoo inks declared at least one pigment ingredient incorrectly. Sixty-one percent of the inks contained pigments of concern, especially red inks. Iron, aluminium, titanium, and copper (most in green/blue inks) were the main metals detected in the inks. The level of metal impurities exceeded current restriction limits in only a few cases. Total chromium (0.35-139 µg/g) and nickel (0.1-41 µg/g) were found in almost all samples. The levels of iron, chromium, manganese, cobalt, nickel, zinc, lead, and arsenic were found to covary significantly. CONCLUSIONS: To prevent contact allergy and toxic reactions among users it is important for tattoo ink manufacturers to follow the regulations and decrease nickel and chromium impurities.


Assuntos
Corantes/análise , Tinta , Tatuagem/legislação & jurisprudência , Corantes/efeitos adversos , Dermatite Alérgica de Contato/etiologia , Rotulagem de Medicamentos/legislação & jurisprudência , Europa (Continente) , Humanos , Metais/análise , Tatuagem/efeitos adversos
5.
Contact Dermatitis ; 85(4): 415-420, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34013976

RESUMO

BACKGROUND: Allergic contact dermatitis to metals is diagnosed by applying a metal salt in a patch test. The bioavailability of the metal salt might depend on the choice of metal salt, the concentration, sweat composition, and pH. OBJECTIVES: The main purpose of this study was to apply chemical speciation modelling, which is based on experimentally derived input data and calculates the concentrations of chemical forms (species) in solutions, to reproduce and discuss clinical patch test results of aluminium and chromium. METHODS: Joint Expert Speciation System (JESS), Hydra/Medusa, and Visual MINTEQ were employed to study the bioavailable fraction and chemical form of clinically applied aluminium and chromium salts as a function of salt type, applied concentration, sweat composition, and pH. RESULTS: Investigated aluminium and chromium salts can have a very low bioavailability with a large dependency on sweat composition, pH, metal salt, and concentration. Both aluminium and chromium ions could shift the pH towards acidic or basic values based on their chemical form. CONCLUSIONS: Reported seasonal and interpatient variability in positive reactions to aluminium is likely related to sweat pH and composition. Potassium dichromate increases the pH, whereas aluminium and trivalent chromium chloride strongly decrease the pH, possibly increasing skin diffusion.


Assuntos
Alumínio/administração & dosagem , Alumínio/efeitos adversos , Cromo/administração & dosagem , Cromo/efeitos adversos , Dermatite Alérgica de Contato/diagnóstico , Testes do Emplastro/métodos , Alumínio/farmacocinética , Disponibilidade Biológica , Cromo/farmacocinética , Dermatite Alérgica de Contato/etiologia , Humanos , Concentração de Íons de Hidrogênio , Suor/química
6.
Biointerphases ; 16(2): 021005, 2021 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-33810641

RESUMO

Gold (Au) nanoparticles (NPs) are widely used in nanomedical applications as a carrier for molecules designed for different functionalities. Previous findings suggested that biological molecules, including amino acids, could contribute to the dissolution of Au NPs in physiological environments and that this phenomenon was size-dependent. We, therefore, investigated the interactions of L-cysteine with 5-nm Au NPs by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS). This was achieved by loading Au NPs on a clean aluminum (Al) foil and immersing it in an aqueous solution containing L-cysteine. Upon rinsing off the excessive cysteine molecules, ToF-SIMS confirmed the formation of gold cysteine thiolate via the detection of not only the Au-S bond but also the hydrogenated gold cysteine thiolate molecular ion. The presence of NaCl or a 2-(N-morpholino)ethanesulfonic acid buffer disabled the detection of Au NPs on the Al foil. The detection of larger (50-nm) Au NPs was possible but resulted in weaker cysteine and gold signals, and no detected gold cysteine thiolate signals. Nano-gold specific adsorption of L-cysteine was also demonstrated by cyclic voltammetry using paraffine-impregnated graphite electrodes with deposited Au NPs. We demonstrate that the superior chemical selectivity and surface sensitivity of ToF-SIMS, via detection of elemental and molecular species, provide a unique ability to identify the adsorption of cysteine and formation of gold-cysteine bonds on Au NPs.


Assuntos
Cisteína/análogos & derivados , Ouro/química , Nanopartículas Metálicas/química , Espectrometria de Massa de Íon Secundário , Cisteína/química , Eletroquímica , Tamanho da Partícula
7.
Contact Dermatitis ; 85(4): 407-414, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33896001

RESUMO

BACKGROUND: Earlier laboratory studies have shown that sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride trigger the release of aluminium (Al) from Finn Chambers (FC). OBJECTIVES: To investigate whether aluminium realease from FC could influence the diagnostic outcome of patch testing with FC. METHOD: A retrospective analysis of patch test results from 2010 to 2019 was performed. A two-sided Fisher's exact test was used to calculate any overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride. RESULTS: A total of 5446 patients had been tested with FC during the study period. There was a significant overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride. Patients with a strong Al allergy had significantly higher amounts of concomitant reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride compared to patients with weak Al allergy. These results were not seen for patients tested with Finn Chambers AQUA. CONCLUSION: In patients with contact allergy to Al, patch testing with Finn chambers could give false-positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride.


Assuntos
Alérgenos/administração & dosagem , Alumínio/efeitos adversos , Dermatite Alérgica de Contato/diagnóstico , Testes do Emplastro/instrumentação , Testes do Emplastro/métodos , Adulto , Reações Falso-Positivas , Feminino , Humanos , Lidocaína/administração & dosagem , Masculino , Myroxylon , Paládio/administração & dosagem , Perfumes/administração & dosagem , Estudos Retrospectivos , Tetracaína/administração & dosagem
8.
Contact Dermatitis ; 83(5): 380-386, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32484247

RESUMO

BACKGROUND: Contact allergy to aluminium (Al) might pose a risk of false-positive readings of patch-test results when testing with Finn chambers. OBJECTIVES: To quantify the release of Al from empty Al Finn chambers, covered Finn Aqua chambers, and Al Finn chambers containing different baseline patch-test substances. METHODS: Al Finn chambers of different conditions and with different patch-test substances were tested in artificial sweat and their Al release was analyzed by atomic absorption spectroscopy and inductively coupled plasma sector field mass spectrometry. RESULTS: The amount of Al released from empty Finn chambers corresponded to a skin dose of 0.03%-0.5% Al chloride hexahydrate applied in plastic chambers. Although most patch-test substances reduced the release of Al from the Finn chambers due to covering the surface, some substances significantly increased the release of Al from the Finn chambers, most notable for Caine mix II 10% pet., Myroxylon pereirae 25% pet., and sodium tetrachloropalladate hydrate 3.0% pet. CONCLUSIONS: The release of Al from Finn chambers corresponds in some cases to clinically relevant concentrations of Al for Al-sensitized individuals.


Assuntos
Alérgenos/efeitos adversos , Alumínio/efeitos adversos , Dermatite Alérgica de Contato/diagnóstico , Dermatite Alérgica de Contato/etiologia , Testes do Emplastro/métodos , Erros de Diagnóstico , Feminino , Humanos , Masculino , Testes do Emplastro/normas
9.
Ann Work Expo Health ; 64(6): 659-675, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32320011

RESUMO

Nickel (Ni) and cobalt (Co) release from chromium-alloy powders (different stainless steels and a nickel-based Inconel alloy) compared with Ni and Co metal powders was investigated at simulated human exposure scenarios (ingestion, skin contact, and inhalation) between 2 and 168 h. All investigated powders consisted of particles sized within the respirable range. The powder particles and their surface reactivity were studied by means of nitrogen adsorption and electrochemical, spectroscopic (X-ray photoelectron spectroscopy and atomic absorption spectroscopy), light scattering, and microscopic techniques. The release of both Ni and Co was highest in the acidic and complexing fluids simulating the gastric environment and an inhalation scenario of small powders (artificial lysosomal fluid). Relatively high corrosion resistance and lower levels of released Ni and Co were observed in all fluids for all alloy powders compared with the corresponding pure metals. The extent of released metals was low for powders with a passive surface oxide. This study strongly emphasizes the importance of considering alloying effects in toxicological classification and/or regulation of Ni and Co in alloys and metals.


Assuntos
Exposição Ocupacional , Ligas , Cobalto , Humanos , Níquel , Pós , Propriedades de Superfície
10.
Contact Dermatitis ; 83(2): 83-87, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32212165

RESUMO

BACKGROUND: Exposure to metalworking fluids (MWFs) is a well-known cause of occupational contact dermatitis. OBJECTIVES: We aimed to (1) determine the amount of nickel, chromium, and cobalt in large samples of used and unused MWFs collected from metalworking plants in Denmark, and (2) evaluate a handheld x-ray fluorescence (XRF) device as a screening instrument for metals in MWFs. METHODS: A handheld XRF device was used to screen for metals in MWFs. All samples were also analyzed for concentrations of nickel, chromium, and cobalt using graphite furnace atomic absorption spectroscopy (GFAAS). RESULTS: GFAAS analysis showed that 13 of 80 samples (16.3%) contained >1 mg/kg (ppm) nickel (range: 6.4-17.7 mg/kg), 3 of 80 (3.8%) contained >1 (range: 1.4-3.1) mg/kg chromium, and 1 of 80 (1.3%) contained 1.3 mg/kg cobalt. XRF-screening detected nickel in eight samples (range: 2.5-15.5 mg/kg), but only one sample with 3.0 (±0.5) mg/kg was found subsequently to contain 9.9 (0.02) mg/kg nickel by GFAAS. Although no chromium was found by XRF analysis, cobalt was found in two samples with 6 (±1.5) mg/kg and 5 (±1.5) mg/kg, subsequently found to contain 0.1 (±0.01) mg/kg and 0.08 (±0.01) mg/kg by GFAAS. Similar concentrations of nickel were found in used (N = 6, range: 6.4-17.7 mg/kg) and unused MWFs (N = 7, range: 9.1-17.3 mg/kg). CONCLUSION: Considerable levels of nickel, chromium, and cobalt were found in some used and unused MWFs indicating that these might represent a source of metal allergy. The XRF device is a poor screening test for these metals in MWFs.


Assuntos
Cromo/análise , Cobalto/análise , Metalurgia , Níquel/análise , Emulsões/química , Óleo Mineral/química , Espectrometria por Raios X/instrumentação , Espectrofotometria Atômica
11.
Contact Dermatitis ; 83(2): 122-124, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32124451

RESUMO

Hexavalent chromium in cement 5-8 mg/kg hexavalent chromium (Cr(VI)) was found in Honduran cement samples, which was slightly higher than in Swedish samples. Variable amounts of Cr(VI) (0.4 and 4.7 mg/kg) found in Swedish cement samples that were older than 1 year. There are still many countries that do not have a compulsory reduction of Cr(VI) in cement. Several measures can be employed to reduce risks related to Cr(VI) in cement.


Assuntos
Cromo/análise , Materiais de Construção/análise , Honduras , Suécia
12.
Environ Sci Pollut Res Int ; 27(11): 12704-12716, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32008194

RESUMO

Surface disinfection of water facilities such as water wells requires measures that can remove pathogens from the walls to ensure a high drinking water quality, but many of these measures might increase corrosion of the contact surfaces (often highly pure steel) and affect the environment negatively due to disinfectant-contaminated waste sludge and wastewater. Today, most treatments worldwide are based on hypochlorites. We investigated the extent of corrosion during treatments of steel at relevant conditions of ozone, sodium, and calcium hypochlorite for drinking water preparation, utilizing weight loss, electrochemical, solution analytical, and surface analytical methods. The ozone treatment caused significantly less corrosion as compared with sodium or calcium hypochlorite with 150-250 mg/L active chlorine. Hypochlorite or other chlorine-containing compounds were trapped in corrosion products after the surface disinfection treatment with hypochlorite, and this risked influencing subsequent corrosion after the surface disinfection treatment. A life cycle impact assessment suggested ozone treatment to have the lowest negative effects on human health, ecosystems, and resources. Calcium hypochlorite showed the highest negative environmental impact due to its production phase. Our study suggests that ozone surface disinfection treatments are preferable as compared with hypochlorite treatments from corrosion, economic, and environmental perspectives.


Assuntos
Compostos Clorados , Desinfetantes , Água Potável , Purificação da Água , Corrosão , Desinfecção , Ecossistema , Humanos , Hipoclorito de Sódio
14.
Nanotoxicology ; 13(10): 1293-1309, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31418618

RESUMO

Millions of people in the world perform welding as their primary occupation resulting in exposure to metal-containing nanoparticles in the fumes generated. Even though health effects including airway diseases are well-known, there is currently a lack of studies investigating how different welding set-ups and conditions affect the toxicity of generated nanoparticles of the welding fume. The aim of this study was to investigate the toxicity of nine types of welding fume particles generated via active gas shielded metal arc welding (GMAW) of chromium-containing stainless steel under different conditions and, furthermore, to correlate the toxicity to the particle characteristics. Toxicological endpoints investigated were generation of reactive oxygen species (ROS), cytotoxicity, genotoxicity and activation of ToxTracker reporter cell lines. The results clearly underline that the choice of filler material has a large influence on the toxic potential. Fume particles generated by welding with the tested flux-cored wire (FCW) were found to be more cytotoxic compared to particles generated by welding with solid wire or metal-cored wire (MCW). FCW fume particles were also the most potent in causing ROS and DNA damage and they furthermore activated reporters related to DNA double- strand breaks and p53 signaling. Interestingly, the FCW fume particles were the most soluble in PBS, releasing more chromium in the hexavalent form and manganese compared to the other fumes. These results emphasize the importance of solubility of different metal constituents of the fume particles, rather than the total metal content, for their acute toxic potential.


Assuntos
Poluentes Ocupacionais do Ar/toxicidade , Células-Tronco Embrionárias/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Nanopartículas/toxicidade , Aço Inoxidável , Soldagem , Poluentes Ocupacionais do Ar/química , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA , Células-Tronco Embrionárias/metabolismo , Células-Tronco Embrionárias/patologia , Humanos , Pulmão/metabolismo , Pulmão/patologia , Metais Pesados/química , Metais Pesados/toxicidade , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Solubilidade
15.
Regul Toxicol Pharmacol ; 106: 15-26, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31028796

RESUMO

Nickel (Ni) and cobalt (Co) are the most common metal allergens upon skin contact at occupational settings and during consumer handling of metals and alloys. A standardized test (EN, 1811) exists to assess Ni release from articles of metals and alloys in massive forms intended for direct and prolonged skin contact, but no corresponding test exists for other materials such as powders or massive forms of alloys placed on the market or to determine the release of Co, for which only limited data is available. Differences in Ni and Co release from massive forms of a range of common stainless steels and some high-alloyed grades compared to Ni and Co metals were therefore assessed in artificial sweat for 1 week at 30 °C according to EN 1811. A comparable modified test procedure was elaborated and used for powders and some selected massive alloys. All alloys investigated released significantly less amount of Ni (100-5000-fold) and Co (200-400,000-fold) compared with Ni and Co metal, respectively. Almost all alloys showed a lower bioaccessible concentration (0.007-6.8 wt% Ni and 0.00003-0.6 wt% Co) when compared to corresponding bulk alloy contents (0.1-53 wt% Ni, 0.02-65 wt% Co). Observed differences are, among other factors, related to differences in bulk composition and to surface oxide characteristics. For the powders, less Ni and Co were released per surface area, but more per mass, compared to the corresponding massive forms.


Assuntos
Ligas/análise , Materiais Biocompatíveis/química , Cobalto/análise , Níquel/análise , Aço Inoxidável/análise , Suor/química , Ligas/metabolismo , Cobalto/metabolismo , Níquel/metabolismo , Oxirredução , Tamanho da Partícula , Pós/análise , Pós/metabolismo , Propriedades de Superfície
16.
Colloids Surf B Biointerfaces ; 173: 751-758, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30384272

RESUMO

Exposure to cobalt (Co), chromium (Cr), and nickel (Ni) occurs often via skin contact and from different dental and orthopedic implants. The metal ions bind to proteins, which may induce structural changes and aggregation, with different medical consequences. We investigated human serum albumin (HSA) aggregation in the presence of CoII, CrIII, and/or NiII ions and/or their nanoparticle precipitates by using scattering, spectroscopic, and imaging techniques, at simulated physiological conditions (phosphate buffered saline - PBS, pH 7.3) using metal salts that did not affect the pH, and at HSA:metal molar ratios of up to 1:8. Co ions formed some solid nanoparticles in PBS at the investigated conditions, as determined by nanoparticle tracking analysis, but the CrIII anions and NiII ions remained fully soluble. It was found that all metal ions induced HSA aggregation, and this effect was significantly enhanced when a mixture of all three metal ions was present instead of any single type of ion. Thus, the metal ions induce aggregation synergistically. HSA aggregates formed linear structures on a mica surface in the presence of CrIII ions. A clear tendency of aggregation and linearly aligned aggregates was seen in the presence of all three metal ions. Spectroscopic investigations indicated that the majority of the HSA molecules maintained their alpha helical secondary structure and conformation. This study highlights the importance of synergistic effects of metal ions and/or their precipitates on protein aggregation, which are highly relevant for implant materials and common exposures to metals.


Assuntos
Cromo/química , Cobalto/química , Nanopartículas/química , Níquel/química , Agregados Proteicos , Albumina Sérica Humana/química , Silicatos de Alumínio/química , Sítios de Ligação , Cátions Bivalentes , Humanos , Concentração de Íons de Hidrogênio , Cinética , Ligação Proteica , Conformação Proteica em alfa-Hélice , Soluções
17.
Contact Dermatitis ; 80(3): 149-155, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30485451

RESUMO

BACKGROUND: Leather exposure has been associated with chromium (Cr) and cobalt (Co) contact dermatitis. Cr(VI) in leather is now restricted to <3 mg/kg in the EU. Cr(III) is not restricted. OBJECTIVES: To analyse 29 differently coloured Cr-tanned leather samples from two Nicaraguan tanneries, and to compare their release of Cr, Cr(VI) and Co with that of leathers produced in Europe. METHODS: Cr, Cr(VI) and Co were extracted in phosphate buffer for 3 hours at 25°C according to EN ISO 17075. Atomic absorption spectroscopy and spectrophotometry were used for detection of the metals in phosphate buffer. RESULTS: There was no difference in total Cr or Cr(VI) release between European and Nicaraguan leathers. There was no association between Cr(VI) and total Cr release. Co was released primarily from leathers of one tannery. Cr(III) was released in significantly higher amounts than Cr(VI). CONCLUSIONS: Future investigations and regulations should focus on Cr(III) and Co as well as on Cr(VI).


Assuntos
Alérgenos/efeitos adversos , Compostos de Cromo/efeitos adversos , Cobalto/efeitos adversos , Dermatite Alérgica de Contato/etiologia , Curtume , Humanos , Teste de Materiais , Nicarágua , Testes do Emplastro
18.
J Biomed Mater Res B Appl Biomater ; 107(3): 858-867, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30102828

RESUMO

The titanium-aluminium (6 wt%)-vanadium (4 wt%) (Ti6Al4V) alloy is widely used as an orthopedic and dental implant material due to its high corrosion resistance in such environments. The corrosion resistance is usually determined by means of electrochemical methods, which may not be able to detect other chemical surface reactions. Literature findings report a synergistic effect of the combination of the abundant protein albumin and hydrogen peroxide (H2 O2 ) on the extent of metal release and corrosion of Ti6Al4V. The objectives of this study were to gain further mechanistic insight on the interplay of H2 O2 and albumin on the metal release process of Ti6Al4V with special focus on (1) kinetics and (2) H2 O2 and albumin concentrations. This was accomplished mainly by metal release and surface oxide composition investigations, which confirmed the combined effect of H2 O2 and albumin on the metal release process, although not detectable by electrochemical open circuit potential measurements. A concentration of 30 mM H2 O2 induced substantial changes in the surface oxide characteristics, an oxide which became thicker and enriched in aluminum. Bovine serum albumin (BSA) seemed to be able to deplete this aluminum content from the outermost surface or at least to delay its surface enrichment. This effect increased with increased BSA concentration, and for time periods longer than 24 h. This study hence suggests that short-term (accelerated) corrosion resistance measurements are not sufficient to predict potential health effects of Ti6Al4V alloys since also chemical dissolution mechanisms play a large role for metal release, possibly in a synergistic way. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 855-867, 2019.


Assuntos
Peróxido de Hidrogênio/química , Soroalbumina Bovina/química , Titânio/química , Ligas , Animais , Bovinos , Corrosão , Oxirredução
19.
ACS Appl Bio Mater ; 2(3): 1006-1016, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-35021391

RESUMO

Gold nanoparticles (AuNPs) are readily functionalized and considered biocompatible making them useful in a wide range of applications. Upon human exposure, AuNPs will to a high extent reside in macrophages, cells that are designed to digest foreign materials. To better understand the fate of AuNPs in the human body, their possible dissolution needs to be explored. In this study, we tested the hypothesis that macrophages, and especially stimulated macrophages, can impact the dissolution of AuNPs in a size-dependent manner. We developed an in vitro method to compare the dissolution of citrate coated 5 and 50 nm-sized AuNPs, in terms of released gold ions as measured by inductive coupled mass spectrometry (ICP-MS), in (i) cell medium (alone) (ii) in medium with macrophages present and (iii) in medium with lipopolysaccharide (LPS) triggered macrophages (simulating inflammatory conditions). We found an evident, time-dependent dissolution of AuNPs in cell medium, corresponding to 3% and 0.6% of the added amounts of 5 and 50 nm AuNPs, respectively, after 1 week (168 h) of incubation. The dissolution of 5 nm AuNPs was further increased to 4% in the presence of macrophages and, most strikingly, 14% was dissolved in case of LPS-triggering. In contrast, only a minor increase was observed for 50 nm AuNPs after 1 week in the presence of LPS-triggered macrophages compared to medium alone. Dissolution experiments in the absence of cells highlighted the importance of biomolecules. Our findings thus show dissolution of citrate coated AuNPs that is dependent on size, presence of macrophages, and their inflammatory state. These findings have implications for understanding the transformation/dissolution and fate of AuNPs.

20.
Langmuir ; 34(45): 13615-13625, 2018 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-30350704

RESUMO

Mucins are high molar mass glycoproteins that assume an extended conformation and can assemble into mucus hydrogels that protect our mucosal epithelium. In nature, the challenging task of generating a mucus layer, several hundreds of micrometers in thickness, from micrometer-sized cells is elegantly solved by the condensation of mucins inside vesicles and their on-demand release from the cells where they suddenly expand to form the extracellular mucus hydrogel. We aimed to recreate and control the process of compaction for mucins, the first step toward a better understanding of the process and creating biomimetic in vivo delivery strategies of macromolecules. We found that by adding glycerol to the aqueous solvent, we could induce drastic condensation of purified mucin molecules, reducing their size by an order of magnitude down to tens of nanometers in diameter. The condensation effect of glycerol was fully reversible and could be further enhanced and partially stabilized by cationic cross-linkers such as calcium and polylysine. The change of structure of mucins from extended molecules to nano-sized particles in the presence of glycerol translated into macroscopic rheological changes, as illustrated by a dampened shear-thinning effect with increasing glycerol concentration. This work provides new insight into mucin condensation, which could lead to new delivery strategies mimicking cell release of macromolecules condensed in vesicles such as mucins and heparin.


Assuntos
Mucinas/química , Nanopartículas/química , Animais , Cálcio/química , Glicerol/química , Mucinas/isolamento & purificação , Tamanho da Partícula , Polilisina/química , Conformação Proteica/efeitos dos fármacos , Solventes/química , Suínos , Viscosidade
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