Background Accurate measurement of corneal thickness is very important during the pre-and post-operative management of corneal surgical procedures,especially laser-assisted in-situ keratomileusis (LASIK),which is the most popular approach to the correction of refractive errors currently.This may be particularly important for the patients who have undergone previous laser refractive surgery with suboptimal outcomes and are being considered for an enhancement procedure.Objective This study was to compare the measuring outcomes of corneal thickness by slit-scanning pachymetry,non-contact specular microscope,anterior segment optical coherence tomography (AS-OCT)and ultrasound pachymetry,with a focus on central and midperipheral (from the central 3.0 mm) region of cornea in post-LASIK eyes.Methods Sixty-four right eyes of 64 patients who received LASIK were collected in Henan Eye Institute,Henan Eye Hospital from March to June 2011 with the equivalent spherical diopter of (-4.75±2.38)D and horizontal corneal diameter of (11.36±0.32)mm.Central corneal thickness was measured on each eye by using non-contact specular microscope (Topcon SP-3000P),slit-scanning pachymetry (Orbscan Ⅱ),AS-OCT and A-type ultrasound pachymetry,respectively,and the paracentral corneal thickness including 12:00,2:00,6:00 and 10:00 meridian was measured using Orbscan Ⅱ,non-contact specular microscope and AS-OCT.The measuring values and the agreement from different instruments were compared and evaluated.Results The mean central corneal thickness was (467.12±31.10)tμm for AS-OCT,(466.67±30.99)μm for ultrasound pachymetry,(441.84 ± 33.65) μm for specular microscopy and (422.51 ± 44.09) μm for Orbsan Ⅱ,respectively,showing a significant difference among the four methods (F =23.730,P =0.000).The central thickness value of the A-type ultrasound pachymetry was significantly higher than that of Orbsan Ⅱ or non-contact specular microscope (q =6.940,6.720,both at P =0.000).Compared with Orbscan Ⅱ,the measuring values of non-contact specular microscope and AS-OCT were significantly higher (q =-5.54,6.940,both at P =0.000),and the measuring value of AS-OCT was significantly higher that of non-contact specular microscope (q =6.800,P =0.000).The lowest difference value (25.3 μm)and the best agreement was found between the ultrasound pachymetry and AS-OCT.The paracentral corneal thickness values in 12:00,2:00,10:00,6:00 meridians were highest for Orbsan Ⅱ and the next for AS-OCT,and non-contact specular microscope had the lowest values,with significantly differences among them (F =5.020,22.950,67.890,18.850,all at P ＜ 0.01).Conclusions The corneal thickness values vary with the different instruments.Orbsan Ⅱ underestimates the central corneal thickness and overestimates the midperipheral corneal thickness,and non-contact specular microscope underestimates both the central and midperipheral corneal thickness.The measuring outcome from AS-OCT has a good agreement with ultrasound pachymetry and therefore they can be used interchangeably.

Objective We are going to establish a robust liquid chromatography-tandem mass spectrometric(LC-MS/MS) method for plasma aldosterone assay.Methods 324 healthy individuals were enrolled in Zhongshan Hospital from February to April in 2016 for reference interval survey.The signallinearity,lower limits of quantitation,precision and accuracy of LC-MS/MS have been evaluated.Results from LC-MS/MS and RIA methods were compared.Software SPSS17.0 software was used for statistical analysis.Results The performance characteristics for the method in terms of linearity,lowerlimits of quantitation,precision and accuracy were verified.Linear range of ALD were between 25-2000 pg/ml;the LC-MS/MS assay had a limit of quantitation of 20 pg/ml for ALD;the intra-and inter-assay CV of ALD were ＜10％ and ＜6％,respectively;the recovery of ALD from serum samples ranged between 97.3 and 105.8％ The reference value of ALD in health people ranged between 21-211.6 pg/ml The regression equation by LC-MS/MS (X) and RIA (Y) was:Y =0.271X + 138.900(r=0.43;n=322).Conclusion LC-MS/MS method is robust and reliable for the analysis of aldosterone in plasma and suitable for clinical application.

Objective:The aim of this study was to develop and validate a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the quantification of melatonin in human serum.Methods:We describe the performance and validation of melatonin by LC-MS/MS. 182 serum samples from the patients diagnosed with Sleep disturbance who visited the Department of Psychiatry at Zhongshan Hospital affiliated to Fudan University from February 2022 to March 2023(56 males,162 females,mean age [45.51±16.31]years), as well as 182 healthy individuals were included(87 males,95 females,mean age [48.55±11.93]years). The two groups were used to assess the application of serum melatonin levels as a diagnostic indicator for sleep disorders (SDs). The liquid chromatography mass spectrometry (LC-MS) system with an chromatography column (2.1×100 mm, 1.8 μm) was used for separation. The column temperature was set at 35 ℃, as well as the mobile phase consisting of a 0.1% formic acid aqueous solution and pure acetonitrile. The flowing rate was set at 0.4 ml/min for gradient elution. The LC-MS/MS method was validated according to guidance documents, including the following parameters: specificity, selectivity, matrix effect, carryover contamination and reproducibility, lower limit of measuring interval, linearity, precision, recovery rate, dilution consistency, and serum sample stability. Then, it was subsequently employed to profile melatonin changes in Sleep disturbance.Results:The lower limit of quantification for melatonin was 1 pg/ml, and the linear range of detection was 1 pg/ml to 500 pg/ml ( r=0.999). The intra-day and intra-batch precision, expressed as the coefficient of variation ( CV), was within the range from 3.07% to 6.86%, which met the requirement of less than 15%. The recovery rate of the spiked samples ranged from 105.91% to 116.30%. The level of serum melatonin in the sleep disturbance group was significantly lower than that in the healthy control group ([2.00(1.00,3.28)] vs [8.35(4.28,14.80)] pg/ml, P<0.001). Conclusions:The LC-MS/MS method we developed for the quantification of melatonin is clinical practicable.