RESUMO
Objetivo: Analizar la degradación de los productos metálicos que constituyen las aleaciones de las prótesis de cadera. Pacientes y método: Se midió, mediante absorción atómica, el titanio, el cromo y el cobalto en la sangre de 58 pacientes con prótesis totales de cadera, compuestas por aleaciones de cromo y cobalto y de titanio, con o sin cementar. Se analizó la evolución de las concentraciones séricas preoperatorias, a los seis y a los 12 meses. Resultados: Encontramos una elevación significativa tras el inicio de la movilización de la articulación, pero sin afectación clínica. Los percentiles 95 de la distribución de concentraciones fueron para el Ti 27 mg/L, Cr 1 mg/L y Co 1,7 mg/L. Conclusión: La elevación de estas concentraciones podría ser indicativa de mal funcionamiento del implante o de desgaste excesivo que podría conducir a toxicidades locales o remotas (AU)
Objective: To analyze the degradation of the metal products contained in hip prosthesis alloys. Patients and method: Atomic absorption measurements were made of the titanium, chromium and cobalt concentrations in the blood of 58 patients with total hip replacement implants made of titanium, chromium and cobalt alloys with or without cementing. The evolution of the serum metal concentrations was assessed based on measurements obtained preoperatively and 6 and 12 months after surgery. Results: A significant increase in serum levels was noted after the start of joint mobilization, though without clinical repercussions. The percentile 95 values of the metal concentration distributions were 27 mg/l for titanium, 1 mg/l in the case of chromium, and 1.7 mg/l for cobalt. Conclusion: The rise in serum metal concentrations could be indicative of poor implant function or excessive wear that in turn could lead to local or disseminated toxicity (AU)
Assuntos
Humanos , Masculino , Feminino , /métodos , /tendências , Metais/análise , Metais/síntese química , Metais/metabolismo , Próteses e Implantes/ultraestrutura , Próteses e Implantes , Titânio/uso terapêutico , Cromo/uso terapêutico , Espectrofotometria Atômica/normas , Espectrofotometria Atômica , Ligas de Cromo/uso terapêutico , Compostos de Cromo/uso terapêutico , Eletroquímica/métodos , Eletroquímica/organização & administração , Análise de VariânciaRESUMO
A silicon chip-based electric detector coupled to bead-based sandwich hybridization (BBSH) is presented as an approach to perform rapid analysis of specific nucleic acids. A microfluidic platform incorporating paramagnetic beads with immobilized capture probes is used for the bio-recognition steps. The protocol involves simultaneous sandwich hybridization of a single-stranded nucleic acid target with the capture probe on the beads and with a detection probe in the reaction solution, followed by enzyme labeling of the detection probe, enzymatic reaction, and finally, potentiometric measurement of the enzyme product at the chip surface. Anti-DIG-alkaline phosphatase conjugate was used for the enzyme labeling of the DIG-labeled detection probe. p-Aminophenol phosphate (pAPP) was used as a substrate. The enzyme reaction product, p-aminophenol (pAP), is oxidized at the anode of the chip to quinoneimine that is reduced back to pAP at the cathode. The cycling oxidation and reduction of these compounds result in a current producing a characteristic signal that can be related to the concentration of the analyte. The performance of the different steps in the assay was characterized using in vitro synthesized RNA oligonucleotides and then the instrument was used for analysis of 16S rRNA in Escherichia coli extract. The assay time depends on the sensitivity required. Artificial RNA target and 16S rRNA, in amounts ranging from 10(11) to 10(10) molecules, were assayed within 25 min and 4 h, respectively.
Assuntos
Técnicas Biossensoriais/instrumentação , Eletroquímica/instrumentação , Microfluídica/instrumentação , Hibridização de Ácido Nucleico/métodos , RNA Ribossômico 16S/análise , Técnicas Biossensoriais/métodos , Eletroquímica/organização & administração , Desenho de Equipamento , Análise de Falha de Equipamento , Escherichia coli/genética , Microfluídica/métodos , Ácidos Nucleicos/análise , Ácidos Nucleicos/química , RNA Bacteriano/análise , RNA Bacteriano/química , RNA Ribossômico 16S/química , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A disposable and mediatorless immunosensor based on a conducting polymer (5,2':5'2"-terthiophene-3'-carboxylic acid) coated screen-printed carbon electrode has been developed using a separation-free homogeneous technique for the detection of rabbit IgG as a model analyte. Horseradish peroxidase (HRP) and streptavidin were covalently bonded with the polymer on the electrode and biotinylated antibody was immobilized on the electrode surface using avidin-biotin coupling. This sensor was based on the competitive assay between free and labeled antigen for the available binding sites of antibody. Glucose oxidase was used as a label and in the presence of glucose, H(2)O(2) formed by the analyte-enzyme conjugate was reduced by the enzyme channeling via HRP bonded on the electrode. The catalytic current was monitored amperometrically at -0.35 V vs. Ag/AgCl and this method showed a linear range of RIgG concentrations from 0.5 to 2 microg/ml with standard deviation +/-0.0145 (n=4). Detection limit was determined to be 0.33 microg/ml.
