ABSTRACT
Objective:To establish and validate an LC-MS/MS method for simultaneous determination of Aβ 1-42, Aβ 1-40, and Aβ 1-38 in cerebrospinal fluid. Additionally, the consistency between this method and three mainstream detection methods was evaluated.Methods:This study involved method establishment, validation, and consistency evaluation. The N15 labeled β-amyloid protein was used as the internal standard. Extraction was performed using Waters MCX 96-wells solid phase extraction plate, and the eluent was collected to QuanRecovery MaxPeak 700 μl plate. At the positive ion mode, the multi-reaction ion monitoring mode based on electric spray ionization is chosen for the determination of CSF Aβ 1-42, Aβ 1-40, and Aβ 1-38. Referring to the CLSI C62-A and EP-15A3 guidelines, the method is evaluated and verified, including quantitation of limit (LOQ), linearity, recovery, precision, and accuracy. In addition, a total of 57 clinical residual CSF samples were collected and the concentrations of Aβ 1-42 and Aβ 1-40 were determined based on manual INNOTEST ELISA assay and Lumipulse G and Roche Elecsys fully automated biochemical analyzers. The comparison analysis and deviation evaluation were conducted by passing-bablok and Bland Altman methods.Results:The analysis time of this method is 8 min, and the LOQ of Aβ 1-42, Aβ1-40 and Aβ1-38 is 0.1 ng/ml, 0.5 ng/ml, and 0.1 ng/ml, respectively, and the linear range can meet the needs of clinical detection. Respectively, the recovery is 86.2%-93.8%, 100.9%-103.9% and 103.3%-107.1%; the total imprecision is 4.7%-7.4%, 3.5%-4.6% and 5.2%-10.9%. The measured values of Aβ 1-42 certified reference materials are all within the allowable uncertainty requirements. Moreover, the carryover rate of three analytes was all≤0.11%. In addition, the correlations of Aβ 1-42 and Aβ1-40 in CSF between this LC-MS/MS method and the INNOTEST ELISA method, Lumipulse G and Roche Elecsys fully automated biochemical analyzers were all deemed good, with correlation coefficient (r) ranging from 0.920 to 0.970. However, the measured values between the four methods were remarkably different.Conclusion:We established and validated a robust method based on LC-MS/MS technology for simultaneous determination of Aβ 1-42, Aβ 1-40, and Aβ 1-38 in CSF. The method is accurate, simple, and suitable for clinical measurements. However, despite good correlations, there were substantial differences in the measurement results of Aβ 1-42 and Aβ 1-40 among different analytical platforms, indicating the need for further promotion of harmonization and standardization processes for AD classic biomarkers.
ABSTRACT
Objective:To evaluate the performance of magnetic beads extraction method (MGE) for the measurement of catecholamine metabolites by liquid chromatography tandem mass spectrometry.Methods:This is a methodological evaluation study. The linearity, limit of quantitation, recovery, precision, and matrix effect of catecholamine metabolites 3-methoxyepinephrine (MN), 3-methoxynorepinephrine (NMN) and 3-methoxytyramine (3-MT) extracted by MGE method were evaluated according to CLSI C62-A. Consensus of method development and validation of liquid chromatography-tandem mass spectrometry in clinical laboratories and other guidelines, 132 clinical residual plasma samples were collected and extracted by automated MGE and traditional solid phase extraction (SPE) method to compare the harmonization of the two extraction methods.Results:The linearity of MN, NMN and 3-MT extracted by automated MGE was>0.99, and the LOQ for MN, NMN and 3-MT were 0.033 5 nmol/L, 0.054 7 nmol/L and 0.011 0 nmol/L, respectively. The repeatability of MN, NMN and 3-MT were 1.3%-5.1%, 2.2%-5.6% and 1.7%-7.1%, respectively. The total imprecision in the laboratory were 1.5%-8.2%, 2.2%-7.7%, 2.1%-11.2%. Although the absolute recovery is low, the average relative recoveries of MN, NMN and 3-MT were 91.5%-108.5%, 92.0%-108.6%, and 89.3%-104.1%, respectively, and the percentage deviation from the expected concentration was within 15%. After isotope internal standard correction, the relative matrix effect is close to 100%, which can compensate for the potential matrix effect. The results of MGE and SPE of MN, NMN and 3-MT showeda good correlation (correlation coefficient r>0.99). The average relative deviations of MN, NMN and 3-MT were 0.2%, -1.4% and 1.0%, respectively. Conclusion:The automatic MGE method hasa good performance in extracting catecholamine metabolites, and is expected to be used in high-throughput analysis of samples in clinical in the future.
ABSTRACT
Background@#Thyroid diseases are highly prevalent worldwide, but their diagnosis remains a challenge. We established reference intervals (RIs) for thyroid-associated hormones and evaluated the prevalence of thyroid diseases in China. @*Methods@#After excluding outliers based on the results of ultrasound screening, thyroid antibody tests, and the Tukey method, the medical records of 20,303 euthyroid adults, who visited the Department of Health Care at Peking Union Medical College Hospital from January 2014 to December 2018, were analyzed. Thyroid-associated hormones were measured by the Siemens Advia Centaur XP analyzer. The RIs for thyroid-associated hormones were calculated according to the CLSI C28-A3 guidelines, and were compared with the RIs provided by Siemens. The prevalence of thyroid diseases over the five years was evaluated and compared using the chi-square test. @*Results@#The RIs for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3) were 0.71–4.92 mIU/L, 12.2–20.1 pmol/L, 3.9–6.0 pmol/L, 65.6–135.1 nmol/L, and 1.2–2.2 nmol/L, respectively. The RIs of all hormones except TT4 differed significantly between males and females. The RIs of TSH increased with increasing age. The prevalence of overt hypothyroidism, overt hyperthyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism was 0.5% and 0.8%, 0.2% and 0.6%, 3.8% and 6.1%, and 3.3% and 4.7% in males and females, respectively, which differed from those provided by Siemens. @*Conclusions@#Sex-specific RIs were established for thyroid-associated hormones, and the prevalence of thyroid diseases was determined in the Chinese population.
ABSTRACT
Inductively coupled plasma mass spectrometry (ICP-MS) technology has the advantages of high sensitivity, wide linear range, good stability, and simple operation, which plays important roles in multi-element quantitative analysis, isotope analysis, speciation analysis and so on. ICP-MS technology can accurately and simultaneously determinate trace elements and toxic elements in different types of human samples, which is important for the diagnosis and treatment of clinical related diseases. Its combination with laser ablation, chromatography and other injection and/or separation technology makes its application much wider.
ABSTRACT
Objective:Analysis of the oxidative products of DNA and RNA in patients with hypertension by determination of 8-oxo Gsn and 8-oxo dGsn, respectively.Methods:This is an observational study. During August and December, 2018, 139 hypertension patients without other chronic diseases with an average age of (49.6±12.4) years old, and 139 apparently healthy volunteers without hypertension with an average age of (48.5±11.7) years old were recruited. Fasting morning urine were collected. The oxidative products of DNA: 8-oxo Gsn and the products of RNA: 8-oxo dGsn were analyzed using liquid chromatography tandem mass spectrometry. Urine Cr(U-Cr), and other serum biomarkers such as ALT, Cr, UA, Glu, TG, TC were analyzed using automatic biochemical analyzers.Results:of 8-oxo Gsn and 8-oxo dGsn were presented as median(quartile). Statistical analysis was performed using SPSS 22.0 and GraphPad Prism 5. Nonparametric test was used to compare the difference of 8-oxo Gsn and 8-oxo dGsn between the hypertension patients and the healthy controls. Results The DNA and RNA oxidative products of 8-oxo Gsn and 8-oxo dGsn in patients with hypertension and their U-Cr-corrected 8-oxo Gsn/U-Cr and 8-oxo dGsn/U-Cr were 14.38(10.39-19.91)ng/ml, 12.97(7.92-18.96)ng/ml, 1.10(0.88-1.38)μg/μmol and 0.96(0.75-1.30) μg/μmol, respectively, which were significantly higher than those in the healthy controls: 11.95(7.52-18.01) ng/ml, 10.12(6.42-15.04) ng/ml, 0.86(0.59-1.21) μg/μmol and 0.72(0.50-1.02) μg/μmol, respectively. After grouped by sex, 8-oxo Gsn in males, 8-oxo Gsn and 8-oxo dGsn in females showed no significant difference between patients with hypertension and healthy controls, however, after U-Cr correction, both males′ and females′ 8-oxo Gsn/U-Cr and 8-oxo dGsn/U-Cr in patients with hypertension were higher than that in the healthy controls.Conclusion:The oxidative products of DNA and RNA in patients with hypertension were significantly higher than that in healthy controls.