Macrophage Biocompatibility of CoCr Wear Particles Produced under Polarization in Hyaluronic Acid Aqueous Solution.

Macrophages are the main cells involved in inflammatory processes and in the primary response to debris derived from wear of implanted CoCr alloys. The biocompatibility of wear particles from a high carbon CoCr alloy produced under polarization in hyaluronic acid (HA) aqueous solution was evaluated in J774A.1 mouse macrophages cultures. Polarization was applied to mimic the electrical interactions observed in living tissues. Wear tests were performed in a pin-on-disk tribometer integrating an electrochemical cell in phosphate buffer solution (PBS) and in PBS supplemented with 3 g/L HA, an average concentration that is generally found in synovial fluid, used as lubricant solution. Wear particles produced in 3 g/L HA solution showed a higher biocompatibility in J774A.1 macrophages in comparison to those elicited by particles obtained in PBS. A considerable enhancement in macrophages biocompatibility in the presence of 3 g/L of HA was further observed by the application of polarization at potentials having current densities typical of injured tissues suggesting that polarization produces an effect on the surface of the metallic material that leads to the production of wear particles that seem to be macrophage-biocompatible and less cytotoxic. The results showed the convenience of considering the influence of the electric interactions in the chemical composition of debris detached from metallic surfaces under wear corrosion to get a better understanding of the biological effects caused by the wear products.

Lipid peroxidation in Down syndrome caused by regular trisomy 21, trisomy 21 by Robertsonian translocation and mosaic trisomy 21.

BACKGROUND: It has been suggested that an increase in oxidative stress in individuals with Down syndrome (DS) may cause adverse effects in the cell membranes through the oxidation of polyunsatured fatty acids. METHODS: We examined erythrocyte malondialdehyde (MDA) levels in 100 individuals of both sexes (34 males and 66 females) with DS, aged from newborn to 29 years. The cytogenetic analysis revealed 90 individuals with regular trisomy 21, four individuals with trisomy 21 by Robertsonian (Rb) translocation, and six individuals with mosaic trisomy 21. DS individuals were divided into six age groups. The control group consisted of 100 healthy individuals of both sexes (40 males and 60 females) who were age-matched with DS subjects. RESULTS: No significant differences were found in erythrocyte MDA levels between the sexes in any of the age groups for the DS group and the control group. We confirmed significantly higher erythrocyte levels of MDA in individuals with DS compared to the control group. A significant difference was observed in erythrocyte MDA levels between DS individuals with trisomy and controls for all age groups, and in individuals with DS due to Rb translocation trisomy. However, in DS individuals with mosaicism, MDA levels depended on the percentage of diploid and trisomy cells. CONCLUSIONS: Our results confirm an increase in lipid peroxidation in patients with DS.

Age-correlated changes of the erythrocyte catalase activity in the Spanish population.

BACKGROUND: Oxygen free radical and reactive oxygen species are involved in many diseases and ageing. Scavening enzymes represent one of the several natural defence mechanisms against free radical induced damage. Catalase (CAT) is an enzyme that is involved in antioxidant defence. OBJECTIVE: In order to establish a comprehensive profile of the erythrocyte CAT activity during ageing, we investigated this activity in human erythrocytes from 2,827 apparently healthy Spanish subjects (1,388 males and 1,439 females). METHODS: We divided the subjects into twelve age groups (newborns and 1-3, 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89, and >90 years of age) to evaluate ageing changes. The CAT activity was measured in haemolysates by the method of Aebi (see text). RESULTS: No significant variations with respect to sex were detected, except for the 70- to 93-year age groups. In these elderly subjects, the CAT activity in males remained constant with no significant variations between age groups, whereas the CAT activity showed a significant increase in females. This fact is considered to be one of the outcomes of the greater longevity in females. Significant age-related modifications in erythrocyte CAT activity appeared in the group of newborns (p < 0.001), in the group 1-3 years of age (p < 0.025), and in the elderly groups: 70-79 years (p < 0.025) and 80-89 years (p < 0.05) of age. CONCLUSION: Our results confirm that the CAT activity in the Spanish population shows an interindividual variability and suggest that this variability may be due, at least in part, to the age of the individuals.