| Objective:The method of detecting serum hydroxyproline(Hyp)by ultraviolet spectrophotometry was investigated,which can be used to detect the level of serum Hyp in the follow-up study,which is convenient for the popularization of the detection of serum Hyp level.To observe the changes of serum Hyp levels in patients with coronary artery disease(CAD)and heart failure(HF)after myocardial infarction,and to explore the clinical value of serum Hyp in these diseases.Methods:Prepare the reagents needed for ultraviolet spectrophotometry to detect serum Hyp,draw the standard curve,determine the best experimental conditions,and evaluate the linearity,imprecision,accuracy,contamination rate and stability of the system.A total of 513 patients with CAD and 100 patients with HF after myocardial infarction were selected from The Affiliated Hospital of Qingdao University from March 2021 to January 2023,and 224 healthy subjects were selected as the control group.The serum samples and general data of all subjects were collected,the differences of serum Hyp levels in each group were compared,and the correlation between serum Hyp level and diseaserelated indexes was analyzed.Results:1.Performance evaluation of ultraviolet spectrophotometry for detection of serum Hyp.The optimum wavelength of the detection system is 558 nm,the best oxidation time of chloramine T is 6min,and the best heating time of chromogenic agent is 20 min.The linear range of the detection system is 0.12～3.19μg/m L.The absorbance after Hyp reaction has a good linear relationship with the concentration of Hyp.The linear regression equation of the standard curve is y=0.0731x+0.0056,and the detection limit is 0.06μg/m L.The recovery rate of this detection system is between 92.95% and 96.06%,the coefficient of variation of intra-batch imprecision is 1.88%～1.99%,the coefficient of variation of interbatch imprecision is 1.91%～2.24%,and the coefficient of variation of inter-day imprecision is 2.57%～2.95%.The carrying pollution rate is 0.81%,and the absorbance of 120 min is stable after oxidation and cooling,which can meet the needs of determination.2.Relationship between serum Hyp and CAD and HF after myocardial infarction.The median serum Hyp level in the control group was 1.24μg/m L(0.81μg/m L,1.62μg/m L),and the median serum Hyp level in CAD patients was 1.08μg/m L(0.65μg/m L,1.55μg/m L).The serum Hyp level in CAD patients was significantly lower than that in the control group.The difference was statistically significant(P<0.05).But there was no significant difference in serum Hyp levels among CAD patients with different coronary artery lesions and different Gensini scores.The median serum Hyp level in CAD patients with chronic myocardial ischemia syndrome(CIS)was 1.14μg/m L(0.69μg/m L,1.72μg/m L),and that in patients with acute coronary syndrome(ACS)was 1.06μg/m L(0.65μg/m L,1.54μg/m L).The serum Hyp level in CIS patients was not significantly different from that in the control group.The serum Hyp level in ACS patients was lower than that in the control group,the difference was statistically significant(P<0.05).The median serum Hyp level in ACS patients with unstable angina pectoris(UA)was1.17μg/m L(0.77μg/m L,1.74μg/m L),and the median serum Hyp level in patients with acute myocardial infarction(AMI)was 0.94μg/m L(0.48μg/m L,1.33μg/m L).There was no significant difference in serum Hyp levels between UA patients and control groups.Serum Hyp levels in AMI patients were lower than those in control groups,the difference was statistically significant(P<0.05).The level of serum Hyp was also negatively correlated with serum high sensitivity cardiac troponin I,glutamic oxaloacetic transaminase,C-reactive protein,total oxidative state and oxidative stress index in patients with AMI(P<0.05).The level of serum Hyp is the independent protective factor of AMI.The serum Hyp level in patients with HF after myocardial infarction(1.46±0.64μg/m L,n=100)was significantly higher than that in the control group(1.27±0.61μg/m L,n=224).The difference was statistically significant(P<0.05).The level of serum Hyp was positively correlated with serum BNP and left ventricular end-diastolic diameter in patients with HF after myocardial infarction(P<0.05).Conclusions:The accuracy,precision,linear range,carrying rate and stability of ultraviolet spectrophotometer for the detection of Hyp can meet the needs of laboratory quantitative detection.The level of serum Hyp was correlated with CAD and HF after myocardial infarction.Detection of serum Hyp level can be used to distinguish AMI from other types of CAD and evaluate the severity of myocardial infarction,which has important guiding significance for clinical treatment.Measuring the level of Hyp can help to evaluate the cardiac function of patients with HF,but it has no diagnostic value for HF. |
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