ABSTRACT
Increased concentrations of circulating metal-degradation products derived from the use of Ti orthopaedic implants may have deleterious biological effects over the long term. Therefore, there is an increasing need to establish the basal level of Ti in the serum of the population (exposed and non-exposed) with appropriate highly sensitive techniques and strategies. With this aim, we have developed a quantitative strategy for the determination of total Ti concentration in human serum samples by isotope dilution analysis using a double-focussing inductively coupled plasma mass spectrometer. Minimizing sample handling and therefore contamination issues, we obtained detection limits of about 0.05 µg L(-1) Ti working at medium resolution (m/Δm 4000). Such extremely good sensitivity permitted us to establish the range of Ti concentration in serum of 40 control individuals (mean 0.26 µg L(-1)) and also to compare it with the level in exposed patients with different Ti metal implants. On the other hand, Ti transport "in vivo" studies have been enabled by online coupling of liquid chromatography (anion-exchange) separation and double-focussing inductively coupled plasma mass spectrometry for sensitive detection of Ti. The development of a postcolumn isotope dilution strategy permitted quantitative characterization of the Ti-transporting biomolecules in human serum. The results for unspiked serum revealed that 99.8% of the Ti present in this fluid is bound to the protein transferrin, with column recoveries greater than 95%.
Subject(s)
Chromatography, High Pressure Liquid/methods , Chromatography, Ion Exchange/methods , Radioisotopes/blood , Spectrophotometry, Atomic/methods , Titanium/blood , Transferrin/analysis , Bone and Bones/drug effects , Bone and Bones/surgery , Calibration , Humans , Limit of Detection , Prostheses and Implants/adverse effects , Protein Binding , Radioisotope Dilution Technique , Radioisotopes/chemistry , Reference Standards , Reproducibility of Results , Transferrin/metabolismABSTRACT
PURPOSE: To determine whether polymorphisms (SNPs) in the genes encoding cytokines and nitric oxide synthase (NOS) might play some role in lumbar disc herniation (LDH). PATIENTS AND METHODS: Case-control study in which 179 patients were retrospectively reviewed. The case group was made of 50 patients with symptomatic LDH diagnosed by MRI while the control group was made of 129 individuals undergoing routine hip or knee arthroplasty with a lifetime lack of low back pain. SNPs in the cytokine genes of IL-1 [IL-1α (-889 C/T), IL-1ß (+3953 T/C)], TNF-α (-308 G/A and -238 G/A) and NOS genes [eNOS (r 27 bp, intron 4 and -786 T/C) and iNOS (22 G/A)]. RESULTS: The CC genotype and C allele of the IL-1ß (+3953 T/C) SNP were significantly more frequent among LDH patients compared to controls. On the other hand, eNOS (-768 T/C) and iNOS (22 G/A) SNPs were significantly more common in the control group. CONCLUSIONS: Carriers of the CC genotype of the IL-1ß (+3953 T/C) SNP were more frequent among LDH patients suggesting some potential role of the IL-1ß SNP on LDH pathogenesis. The eNOS (-786 T/C) and iNOS (22 G/A) SNPs were more frequent among the control subjects, suggesting their possible protective role against LDH. Genotyping these SNPs could be useful to identify persons with an increased lifetime risk of disc herniation in whom measures to avoid LDH could be implemented.