Propranolol plasma monitoring in children submitted to surgery of tetralogy of Fallot by a micromethod using high performance liquid chromatography

OBJECTIVE: To evaluate the analytical micromethod using liquid chromatography for the quantification of propranolol in children submitted to surgery of tetralogy of Fallot (TLF). Methods: Only 0.2 mL of plasma is required for the assay. Peaks eluted at 8.4 (Propranolol) and 17.5 min (verapamil, internal standard) from a C18 column, with a mobile phase 0.1 M acetate buffer, pH 5.0, and acetonitrile (60:40, v/v) at flow rate 0.7 mL/min, detected at 290 nm (excitation) and 358 nm (emission). Surgery was started 776 min of drug administration (8.7mg, mean); seven blood samples were collected from six patients (4M/2F; 2.1yrs;11.5kg; 0.80m; 18.9kg/m²). RESULTS: Confidence limits of the method showed high selectivity and recovery, sensitivity of 0.02ng/mL, good linearity (0.05-1000ng/mL), precision of 8.6 percent and accuracy of 3.1 percent. The mean duration of surgery was 283.2min, with the patients remaining under cardiopulmonary bypass (CPB) for 114min. A declining curve of propranolol plasma concentration was obtained after the last dose in the night that preceded the day of surgery. Plasma concentration also was normalized with hematocrit due to the hemodilution caused by the CPB procedure. On the other hand a decrease on drug plasma concentration was obtained between periods, the beginning of surgery to the postoperative day 2 (7.09 ng/mL and 0.05 ng/mL, p<0.05 respectively) and from the end of CPB to the postoperative day 2 (2.79ng/mL e 0.05ng/mL, p<0.05). CONCLUSION: Propranolol monitoring of plasma concentrations of children (TLF) normalized after the last preoperative dose revealed a decline from the beginning of surgery to the second postoperative day, suggesting that, once redistribution was restored, propranolol washout was complete.

OBJETIVO: Avaliar o micrométodo analítico empregando a cromatografia líquida para quantificação de propranolol em crianças operadas de tetralogia de Fallot (TLF). MÉTODO: Requereu-se apenas volumes de 0,2mL de plasma para a realização do ensaio. Os picos foram eluídos em 8.4 (Propranolol) e 17.5 min (verapamil, padrão interno) de uma coluna C18, com fase móvel (tampão acetato 0,1 M pH 5,0 e acetonitrila, 60:40, v/v) em fluxo de 0,7 mL/min, sendo detectados em 290 nm (excitação) e em 358 nm (emissão). A cirurgia iniciou-se 776 min depois da dose administrada (8,7mg, média) e sete amostras de sangue foram coletadas de seis pacientes (4M/2F; 2,1 anos;11,5kg; 0,80m;18,9kg/m²). RESULTADOS: Os limites de confiança do método analítico evidenciaram alta seletividade e recuperação, sensibilidade (0,02ng/mL), boa linearidade (0,05-1000ng/mL), precisão de 8,6 por cento e exatidão de 3,1 por cento. A duração média da cirurgia foi de 283,2min, com os pacientes em circulação extracorpórea (CEC) durante 114min. Uma curva de declínio do propranolol no plasma foi obtida após a última dose na noite que precedeu o dia da intervenção. A concentração plasmática foi normalizada com o hematócrito devido à hemodiluição causada pela CEC. Por outro lado obteve-se decréscimo nas concentrações plasmáticas entre os períodos início da cirurgia para o 2° dia de pós-operatório (7,09 ng/mL e0,05 ng/mL, p<0,05 respectivamente) e do final da CEC para o 2° dia de pós-operatório (2,79ng/mL e 0,05ng/mL, p<0,05). CONCLUSÃO: O monitoramento das concentrações plasmáticas normalizadas do propranolol, em crianças com TLF, após a última dose pré-operatória revelou decaimento do início da cirurgia para o segundo pós-operatório, sugerindo que após a correção cirúrgica, uma vez restaurada a distribuição, a eliminação do fármaco foi completa.

Applied study on magnetic nanometer beads in preparation of genechip samples / 华中科技大学学报（医学）（英德文版）

A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid-phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA-A PCR amplification system and a small HLA-A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe2O3) were set up. The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano-beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab-on-a-chip.

Measurement of total iron binding capacity in Thai Blood donors by a micro-technique.

A micro-method with a high percentage of reproducibility and recovery was used to determine TIBC in 207 Thai blood donors. The mean values of TIBC were found to be 312 mu-g per 100 ml (S.D. = 46) in 149 male and 339 mu-g per 100 ml (S.D. = 58) in 58 female subjects respectively. There was a good relationship between these values and those obtained from the macro-technique using bathophenathroline in 105 samples. The corresponding results determined by the macro-technique were 328 mu-g per 100 ml (S.D. = 59) and 328 mu-g per 100 ml (S.D. = 74) in 106 male and 40 female subjects respectively. These results were fond to be in accordance with the result reported previously by other authors using different methods. The micro-method used in the present studies needed only 0.2 ml of serum. Determination of TIBC by this method and serum iron by the ultra-micro technique would be very valuable in the investigation of anaemia in the field studies particularly in infants.