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PubMed2006

Cr(III) and Cr(VI) in leather and elicitation of eczema.

The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and soluble Cr(III) using the DIN 53314 and the DS/EN 420 methods. Subsequently, a group of 15 patients with a history of foot eczema and leather exposure was exposed to a selection of 14 chromium- and 1 vegetable-tanned leather sample on the upper back for 48 hr. In addition, one leather sample was used for a prolonged 14-day exposure study. In total, 4 of the 15 patients reacted to at least one leather sample, and 5 of the 14 leather samples elicited a reaction in at least 1 patient. The prolonged exposure study demonstrated that an extended exposure period may reveal allergenic potential of a leather sample not otherwise identified using an ordinary 48-hr exposure period. No relation was observed between the measured content of Cr(VI) and soluble Cr(III) in the leather and the elicitation of eczema. Thus, in order to evaluate the quality of chromium-tanned leather in relation to preventing allergic skin reactions, other more clinical relevant methods reflecting the actual bioavailable Cr(III) and Cr(VI) fractions should be developed.

Chromium Compounds↗
PubMed1982

Immunochemical characterization of Candida albicans cell wall antigens: specific determinant of Candida albicans serotype A mannan.

We investigated the chemical structure of the specific determinant in the mannan of Candida albicans M-1012 (serotype A) strain. Acetolysis of the mannan, obtained by alkali extraction and purified as the copper complex, gave mannose and six oligosaccharides (from di- to hexasaccharide) and a small amount of a heptasaccharide. We examined the inhibition by these oligosaccharides up to hexaose of the precipitin reaction between anti-factor 6 serum specific for serotype A and homologous mannan, and found that the mannohexaose was the most effective inhibitor. These, and results obtained by proton magnetic resonance (PMR) spectroscopy, methylation analysis, and other structural studies, suggest that the main component of this hexaose consists of one terminal alpha (1-3) linkage in addition to four alpha (1-2) linkages, and that this alpha (1-3)-containing mannohexaose may be responsible for the specificity of antigenic factor 6. Further results obtained by analyses of polarimetry, PMR spectroscopy, and chromium trioxide oxidation-methylation of C. albicans M-1012 mannan has a beta-linkage in addition to alpha-linkages, and that the mode of the beta-linkage is mainly (1-6) linkage. Further evidence obtained by Smith degradation-methylation analysis and by quantitative precipitin reactions of intact and acid-degraded mannan suggests that the antigenic determinant of antigenic factor 6 may be bound, via the beta (1-6) linkage, to C-6 of mannose residues involved in oligosaccharide side chains of serotype A mannan.

Antigens, Fungal↗
PubMed1981

A simple method for the use of gallocyanin-chrome alum as an electron strain.

A method has been elaborated for the demonstration of DNA in the electron microscope. The method uses glutaraldehyde fixed tissue pieces from which RNA has been removed by incubation with RNase. DNA is stained by gallocyanin-chrome alum in the tissue block. Embedding and cutting is done in the usual manner. The method is based on histochemical observations at the light microscope level which show sufficient specificity and a good stoichiometry of the staining reaction.

Animals↗
PubMed1980

Complex fucolipids of hog gastric mucosa. Structure of the ceramide eikosahexoside.

The structure of a complex fucolipid from hog gastric mucosa containing twenty sugar residues and exhibiting blood-group (A + H) activity has been investigated. Based on the results of immunological assays, partial acid hydrolysis, sequential degradation with specific exoglycosidases, oxidation with periodate and chromium trioxide, and permethylation analysis, we suggest that the carbohydrate chain of this fucolipid contains four termini. One of the termini bears beta Gal1 leads to 4 beta GlcNAc disaccharide, two bear blood-group A determinant and one bears H determinant. Two of the branches, terminated by beta Gal1 leads to 4 beta GlcNAc and blood-group A determinant, and two terminated by blood-group A and H determinants, are linked through beta Gal1 leads to 4 beta GlcNAc1 leads to 3/6 and beta Gal1 leads to 4 beta GlcNAc1 leads to 4 beta GlcNAc1 leads to 3/6 to the galactose residue adjacent to glucosylceramide core.

ABO Blood-Group System↗
PubMed1984

Structural studies on the O-glycosidically linked carbohydrate chains of glucoamylase G1 from Aspergillus niger.

Glucoamylase G1 from Aspergillus niger contains an unusual type of carbohydrate-protein linkage, involving mannose O-glycosidically linked to serine and threonine. The majority of the neutral oligosaccharides of glucoamylase G1 are located in a region of about 70 amino acid residues which carries about 35 oligosaccharide units [(1983) Carlsberg Res. Commun. 48, 517-527]. Structural analysis was performed on the O-linked carbohydrates of a tryptic fragment from glucoamylase G1 comprising the segment characterized by a high degree of glycosylation. The carbohydrate structures released by trifluoroacetolysis were elucidated using sugar analysis, methylation analysis, mass spectrometry, chromium trioxide oxidation, digestion with alpha-mannosidase and 1H-NMR spectroscopy. The following structures could be identified. (formula; see text)

Aspergillus niger↗
PubMed1991

Chemical structure of the carbohydrate backbone of Vibrio parahaemolyticus serotype 012 lipopolysaccharide.

The chemical structure of the saccharide portion of Vibrio parahaemolyticus serotype 012 lipopolysaccharide was studied. Using chemical degradation and modification, as well as methylation analysis in combination with GLC-MS, laser-desorption mass spectrometry and 1H-NMR and 13C-NMR spectroscopy, the carbohydrate backbone of the lipopolysaccharide was characterized as a branched decasaccharide with the following structure: (formula; see text) In the native lipopolysaccharide two additional phosphate groups are present and 3-deoxy-D-threo-hexulosonic acid and D-galacturonic acid are bound via acid-labile linkages.

Carbohydrate Conformation↗
PubMed1994

Kinetics and specificity of nickel hypersensitivity in the murine model.

Nickel contact dermatitis appears to be almost exclusively a disease of females despite the increasing exposure of males to nickel. Successful murine models of nickel allergic contact dermatitis have been described. The purpose of this study is to investigate the kinetics and specificity of the response in this model and to examine if any differences exist between male and female. Mice were sensitised epicutaneously with nickel sulphate in aqueous solution of varying concentration, volume and duration of application. Following intradermal challenge, dose dependent response kinetics which approximated linearity were demonstrated upto the point of toxicity. Sensitised mice were challenged with Cobaltous chloride, Chromic chloride and Cupric sulphate and demonstrated no evidence of cross sensitivity to cobalt or chrome. Copper produced an irritant response making interpretation difficult. Earlier and stronger responses were observed in female mice, however these differences fell short of statistical significance. The results of the present study therefore establishes a reliable model for nickel hypersensitivity, that demonstrates both specificity and dose dependent kinetics without significant sex differences.

Animals↗
PubMed1996

Fatigue of resin cement-base metal alloy bond strength.

PURPOSE: Strong durable bonds between resin cements and metal alloys are critical to the success of resin-bonded, resin-veneered, or resin-retained prostheses. However, few comprehensive, comparative evaluations of materials or the fatigue effects of thermal cycling have been reported. The rate of strength loss may be a more important predictor of long-term success than bond strength. The purpose of this study was to investigate the effects of artificial aging by thermal cycling and resin cement type on the bond strengths to a base metal alloy. MATERIAL AND METHODS: This study investigated the effect of the number of thermal cycles (0, 1, 10, 100, 1,000, and 10,000) on the bond strengths of nine fixed prosthodontic resin cements. Specimens were assigned randomly to thermal cycle number/cement type test groups. Cylinders of a base metal alloy were bonded in an end-to-end configuration. One end of each bonded specimen was insulated, and the specimen was thermal cycled. Then, the bonds were tested in shear and bond strengths calculated. RESULTS: Two-way ANOVA revealed that the effects of cement type, the number of thermal cycles, and their interaction all significantly affected bond strength (p < .0001). Multiple range analysis showed that some cements had significant trends to lose bond strength with thermal cycling (p < .05), while others did not (p > .05). CONCLUSIONS: Both the type of resin cement and the amount of thermal cycling influenced bond strength to a base metal alloy. Some materials displayed more rapid loss of bond strength than others.

Analysis of Variance↗
PubMed2000

In vivo interaction of trivalent chromium with yeast plasma membrane, as revealed by EPR spectroscopy.

The in vivo effects of CrCl(3) on an ergosterol-producing 33 erg(+) strain of the eukaryotic yeast Candida albicans, and on its ergosterol-deficient erg(-)2 mutant, were studied by using electron paramagnetic resonance spectroscopy. A 5-doxylstearic acid spin probe was applied to label the membranes. The absence of ergosterol, an increased accumulation of Delta(8) sterols, a decreased fatty acid chainlength and a lower proportion of unsaturated fatty acids of the erg(-)2 mutant resulted in a higher membrane rigidity and an increased sensitivity to Cr(III) than those of the parental 33 erg(+) strain. Cr(III) significantly increased the fluidity of the spin labelled membranes, this being more pronounced for the erg(-)2 mutant. The break in the slopes measured for the erg(-)2 mutant was decreased (DeltaAT approximately 4 degrees C) from 17 to 13 degrees C. Cr(III) treatment for 10 h caused a loss of metabolites adsorbing at 260 nm: this loss was 40% for 33 erg(+) and 60% for erg(-)2. This decriptification process might be the main cause of growth inhibition and cell killing by the impermeable Cr(III) ions.

Candida albicans↗
PubMed1983

Influence of detergent washing powders on minimal eliciting patch test concentrations of nickel and chromium.

Minimum eliciting levels of nickel have been estimated in 25 nickel-sensitive subjects, and of chromium in 14 chromium-sensitive subjects by patch tests with aqueous solutions of the respective metals. The minimum level of each metal required to provoke a patch test reaction was considerably greater than that found in fabric washing powder solutions and was in the majority of patients tested of the order of 112 ppm nickel (0.05% nickel sulphate) or 885 ppm hexavalent chromium (0.25% potassium dichromate). One nickel-sensitive subject and one chromium-sensitive subject reacted to 1 ppm of the respective metal. Fabric washing powder did not significantly alter the patch test reaction to nickel sulphate or provoke reactions in nickel- or chromium-sensitive subjects. EDTA significantly reduced the number and severity of patch test reactions to nickel sulphate but not those to potassium dichromate or trivalent chromium.

Chlorides↗
PubMed1992

Permeation of chromium salts through human skin in vitro.

Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration indicating a limited reduction ability of the skin in vitro.

Chlorides↗
PubMed1996

Chromium allergy in consecutive patients in a country where ferrous sulfate has been added to cement since 1981.

Cement eczema used to be a common occupational disease in Denmark. Since 1981, ferrous sulfate has been added to all cement produced in Denmark to reduce the amount of soluble hexavalent chromate to below 2 mg/kg (2 ppm). The aim of the study was to analyse a material of consecutive chromate-sensitive patients in an urban tertiary referral centre with respect to primary cause of sensitization, in a geographical area where the risk of chromate exposure from cement had been reduced. In the 6-year period January 1989 to December 1994, a total of 4511 patients were patch tested with the European standard series, including chromate. 79 patients, 31 male and 48 female, were diagnosed as chromate sensitive. Relevant chromate exposure was established in 34 of these 79 patients. Leather was the most frequent source of chromate sensitization (19 out of 34) (47%). Chromate sensitization from cement was considered likely in 10 out of 34 subjects. Of these, 7 had been sensitized before 1981, 2 had been sensitized by non-occupational exposure to cement, and only 1 had been sensitized from occupational cement exposure in the 6-year period.

Adult↗
PubMedDate not supplied

Evaluation of a 4-META adhesive cement.

This study investigated the shear bond strength of a new 4-META adhesive cement (C & B-Metabond) to dentin and Ni-Cr-Be alloy (Rexillium III). Fifteen human molar teeth had dentin bonding sites prepared by grinding away the enamel on a water-cooled abrasive wheel to a 600 grit. Fifteen metal alloy specimens were cast, ground to a 600 grit, and air abraded with 50 micron alumina. The 4-META cement was applied to the dentin and metal in accordance with the manufacturer's instructions. After 24 hours in water at 37 degrees C, the shear bond strengths were recorded. The mean bond strength to dentin and the metal alloy was 20.1 megapascals.

Adhesives↗
PubMedDate not supplied

Evaluation of a 4-META porcelain repair system.

A recently introduced porcelain repair system utilizing 4-META (Etch-Free Primer with C & B-Metabond) was evaluated for bond strength to porcelain. This system purportedly eliminates hydrofluoric acid-etching and silane pretreatment. Forty porcelain specimens were prepared and treated with the 4-META repair system. A resin cylinder was bonded to the treated porcelain surface. Twenty of the specimens were tested after 24 hours while the other 20 were tested after thermocycling (800 cycles at 6 degrees C to 60 degrees C). The mean bond strengths were: 24 hours 17.4 MPa (+/- 4.8), thermocycled 19.1 MPa (+/- 7). Cohesive failure of the porcelain occurred in all of the specimens, both the 24 hour and the thermocycled. These bond strengths compare favorably with or exceed those of other porcelain repair systems tested in other studies.

Adhesives↗