Evaluation model for myocardial injury caused by cold exposure and construction method thereof

Abstract

The invention discloses a construction method of an assessment model for myocardial injury caused by cold exposure. The construction method comprises the following steps: S1, data acquisition: acquiring demographic parameters of a subject; obtaining the expression quantity of the mitochondria-related endoplasmic reticulum membrane protein of the subject; circulation physiological parameters of the subject are obtained; acquiring other physiological parameters of the subject; the method comprises the following steps: acquiring myocardial hypersensitive troponin I of plasma of a subject, and identifying whether myocardial injury exists or not; s2, risk parameter screening: taking the parameters as evaluation parameters, and screening risk parameters related to myocardial injury caused by cold exposure; and S3, regression analysis: carrying out statistical analysis on the screened risk parameters by using multivariable logistic regression, and constructing a cold exposure induced myocardial injury assessment model. According to the invention, the risk probability of circulatory dysfunction and acute cardiovascular events when the human body is exposed in a cold environment can be effectively evaluated.

Description

Technical Field

[0001] The present invention relates to an assessment model for myocardial injury caused by cold exposure based on molecular biological indicators and circulating physiological parameters, and also relates to a corresponding construction method, belonging to the technical field of medical molecular diagnosis. Background Art

[0002] China has a vast cold region. In recent years, more and more people have entered and stationed in the cold region to carry out work. However, the cold environment poses a severe physiological challenge to the body. Long-term exposure will lead to functional changes in multiple organs and tissues. Among them, the cardiovascular system is most significantly affected. Due to the increased activity of the sympathetic nervous system, which mediates vasoconstriction to increase peripheral vascular resistance, stimulates the enhancement of cardiac contractility, resulting in a significant increase in blood pressure and heart rate, increasing the cardiac burden. With the increase in left ventricular afterload, myocardial tissue is prone to injury, which may affect cardiac function and cause symptoms such as chest tightness, fatigue, palpitations, and syncope. In severe cases, it may induce acute cardiovascular events. Therefore, evaluating myocardial injury caused by cold exposure, identifying high-risk populations with maladaptation of the cardiovascular system, and proposing prevention and treatment measures are of great significance for ensuring the safety of cold region workers and improving mission effectiveness. However, myocardial injury caused by cold exposure is relatively concealed, and early identification is very difficult. At present, the clinical diagnosis of myocardial injury mainly relies on the detection of post-injury biomarkers such as hypersensitive cardiac troponin I (cTnI) in the myocardium. Such indicators only increase significantly after irreversible damage to myocardial cells and cannot achieve early warning. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the primary technical problem to be solved by the present invention is to provide a construction method for an assessment model of myocardial injury caused by cold exposure based on molecular biological indicators and circulating physiological parameters.

[0004] Another technical problem to be solved by the present invention is to provide an assessment model of myocardial injury caused by cold exposure obtained by the above construction method.

[0005] Another technical problem to be solved by the present invention is to provide a data analysis method based on the above assessment model of myocardial injury caused by cold exposure.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A construction method for an assessment model of myocardial injury caused by cold exposure includes the following steps:

[0008] S1. Data acquisition: Obtain the demographic parameters of the subjects; obtain the expression levels of mitochondrial-associated endoplasmic reticulum membrane proteins of the subjects; obtain the circulating physiological parameters of the subjects; obtain other physiological parameters of the subjects; obtain hypersensitive cardiac troponin I in the plasma of the subjects and identify whether there is myocardial injury;

[0009] S2. Risk parameter screening: Using the demographic parameters of the subjects, the expression levels of the mitochondrial-associated endoplasmic reticulum membrane proteins of the subjects, the circulatory physiological parameters of the subjects, and the other physiological parameters of the subjects as evaluation parameters, screen the risk parameters related to myocardial injury caused by cold exposure;

[0010] S3. Regression analysis: Statistically analyze the screened risk parameters using multivariate logistic regression to construct an evaluation model for myocardial injury caused by cold exposure.

[0011] Preferably, the demographic parameters include age, gender, body mass index, and cold region exposure time.

[0012] Preferably, the mitochondrial-associated endoplasmic reticulum membrane proteins include MFN2, PACS2, FUNDC1, FIS1, DRP1, and TOM40.

[0013] Preferably, the circulatory physiological parameters include blood pressure variability, blood pressure load value, heart rate, blood pressure, ejection fraction, and stroke volume.

[0014] Preferably, the other physiological parameters include blood oxygen saturation and core body temperature.

[0015] Preferably, the risk parameters include the expression level of the mitochondrial-associated endoplasmic reticulum membrane protein MFN2, the circulatory physiological parameters of blood pressure variability and blood pressure load value.

[0016] Preferably, the construction method further includes S4 display calculation steps: Use a nomogram to display the relationship between the risk factor data and the data after regression analysis; According to the specific values of the three variables, calculate the scores of each variable respectively; Add the scores of the three variables to get the total score, and correspondingly obtain the probability of the occurrence of the clinical endpoint event.

[0017] Preferably, the calculation method in S4 is as follows: First, set the blood pressure load value, calculate the physiological parameter range of blood pressure variability, i.e., MFN2 protein. The range of the blood pressure load value is 0 - 0.5, the range of blood pressure variability is 8 - 36, and the range of relative expression level of MFN2 protein is 0.6 - 2.1. For every 1 - unit decrease in the expression level of MFN2 protein, the score of this index will increase by 66.67 points; for every 1 - unit increase in blood pressure variability, the score of this index will increase by 3.81 points; for every 1 - unit increase in the blood pressure load value, the score of this index will increase by 144.00 points. When the total score is lower than 131.20 points, the probability of myocardial injury caused by cold exposure is less than 10%; when the total score is between 131.20 and 143.20 points, the probability is between 10% - 30%; when the total score is between 143.20 and 151.20 points, the probability is between 30% - 50%; when the total score is between 151.20 and 159.20 points, the probability is between 50% - 70%; when the total score is between 159.20 and 171.20 points, the probability is between 70% - 90%; when the total score exceeds 171.20 points, the probability of myocardial injury caused by cold exposure exceeds 90%.

[0018] A myocardial injury assessment model caused by cold exposure is constructed by the above - mentioned construction method.

[0019] A data analysis method for myocardial injury caused by cold exposure includes the following steps:

[0020] Obtain the expression level of MFN2 protein of the person to be evaluated;

[0021] Measure the blood pressure variability of the person to be evaluated;

[0022] Measure the blood pressure load value of the person to be evaluated;

[0023] Input the expression level of MFN2 protein, blood pressure variability, and blood pressure load value into the above - mentioned myocardial injury assessment model caused by cold exposure to analyze the myocardial injury data of the person to be evaluated in a cold environment.

[0024] A myocardial injury assessment system caused by cold exposure includes:

[0025] An MFN2 protein expression level detection device for obtaining the expression level of MFN2 protein of the person to be evaluated;

[0026] A blood pressure variability measurement device for measuring the blood pressure variability of the person to be evaluated;

[0027] A blood pressure load value measurement device for measuring the blood pressure load value of the person to be evaluated;

[0028] The cold exposure-induced myocardial injury assessment device is used to assess the occurrence of myocardial injury in a person to be evaluated in a cold environment by using the above-mentioned cold exposure-induced myocardial injury assessment model based on the expression level of MFN2 protein, blood pressure variability, and blood pressure load value of the person to be evaluated.

[0029] Compared with the prior art, the present invention uses a method of combining molecular biological indexes of the human body with circulatory physiological parameters to evaluate the possibility of cold exposure-induced myocardial injury after the human body is exposed to a cold environment, with high sensitivity and strong specificity, and can early identify individuals with cold exposure-induced myocardial injury at risk of circulatory dysfunction and acute cardiovascular events. Brief Description of the Drawings

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts do not necessarily draw according to the actual scale.

[0031] Figure 1 It is a flowchart of the method for assessing cold exposure-induced myocardial injury according to an embodiment of the present invention;

[0032] Figure 2 It is a volcano plot of protein expression differences between the cold exposure-induced myocardial injury group and the control group according to an embodiment of the present invention;

[0033] Figures 3A - 3F It is a comparison chart of the expression levels of mitochondrial-associated endoplasmic reticulum membrane proteins between the cold exposure-induced myocardial injury group and the control group according to an embodiment of the present invention;

[0034] Figure 4 It is a comparison chart of the expression levels of MFN2 protein among the cold exposure-induced myocardial injury group, the control group, and other cardiovascular disease-induced myocardial injury groups according to an embodiment of the present invention;

[0035] Figure 5 It is a comparison chart of blood pressure variability among the cold exposure-induced myocardial injury group, the control group, and other cardiovascular disease-induced myocardial injury groups according to an embodiment of the present invention;

[0036] Figure 6 It is a comparison chart of blood pressure load values among the cold exposure-induced myocardial injury group, the control group, and other cardiovascular disease-induced myocardial injury groups according to an embodiment of the present invention;

[0037] Figure 7 It is a line graph of the correlation between myocardial hypersensitive troponin I in plasma and baseline blood pressure variability according to an embodiment of the present invention;

[0038] Figure 8Line graph showing the correlation between highly sensitive cardiac troponin I in plasma and baseline blood pressure load value in the embodiments of the present invention;

[0039] Figures 9A - 9D Receiver operating characteristic curve for evaluating individuals with myocardial injury caused by cold exposure in the embodiments of the present invention;

[0040] Figure 10 Nomogram model for evaluating individuals with myocardial injury caused by cold exposure in the embodiments of the present invention;

[0041] Figure 11 Calibration curve of the nomogram model for evaluating individuals with myocardial injury caused by cold exposure in the embodiments of the present invention;

[0042] Figure 12 Receiver operating characteristic curve for evaluating individuals with myocardial injury caused by cold exposure using the validation set in the embodiments of the present invention. Detailed implementation manners

[0043] Embodiments of the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and therefore are only examples and cannot be used to limit the protection scope of the present invention.

[0044] It should be noted that unless otherwise specified, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0045] In order to establish an evaluation model for myocardial injury caused by cold exposure in the embodiments of the present invention, relevant factors for myocardial injury caused by cold exposure need to be found first. In one embodiment of the present invention, the number of subjects is 70, all of whom are 70 healthy people (aged between 20 and 40 years old and other cardiovascular system diseases have been excluded) who have lived in Mohe area of Heilongjiang Province (located at 52 - 53° north latitude, with a winter of up to 8 months, an average minimum winter temperature of -23°C, and a historical extreme minimum temperature of -53°C) for more than 1 year and have been engaged in outdoor cold environment work for a long time.

[0046] According to the "Cold Degree Rating Table" formulated in the meteorological field to describe the cold degree, there are a total of eight levels: the first level "extremely cold" is below -40°C; the second level "severely cold" is from -30°C to -39.9°C; the third level "very cold" is from -20°C to -29.9°C; the fourth level "great cold" is from -10°C to -19.9°C; the fifth level "slight cold" is from -5°C to -9.9°C; the sixth level "light cold" is from 0°C to -4.9°C; the seventh level "slight chill" is from 0°C to 4.9°C; the eighth level "cool" is from 5°C to 9.9°C. In the embodiments of the present invention, "cold" refers to a temperature below -20°C, that is, not exceeding the third level "very cold".

[0047] Such as Figure 1As shown in the figure, an assessment model for cold exposure-induced myocardial injury based on molecular biological indicators and cyclic physiological parameters provided by an embodiment of the present invention includes at least the following steps:

[0048] S1. Obtain the demographic parameters of the subject

[0049] Record the demographic characteristics of the subject, which include age, gender, body mass index (BMI), and exposure time in the cold region. The cold region exposure time refers to the cumulative duration of the subject's past life and work in a severe cold region, with the unit of year.

[0050] S2. Obtain the expression levels of mitochondrial-associated endoplasmic reticulum membrane proteins of the subject

[0051] For molecular biological indicators, since myocardial tissue is rich in mitochondria, and the abnormal mitochondrial function under cold environment is significantly correlated with myocardial injury and the decline of cardiac function, mitochondrial-associated endoplasmic reticulum membrane proteins related to mitophagy and energy metabolism regulation are selected to construct an assessment model for cold exposure-induced myocardial injury. In this embodiment, the selected proteins specifically include:

[0052] MFN2: Mitofusin 2;

[0053] PACS2: Phosphofurin acidic cluster sorting protein 2;

[0054] FUNDC1: Protein 1 with Fun14 domain;

[0055] FIS1: Mitochondrial fission protein 1;

[0056] DRP1: Dynamin-related protein 1;

[0057] TOM40: Translocase of the outer mitochondrial membrane 40.

[0058] When determining the molecular biological indicators, perform proteomic analysis on the blood samples of the subjects to screen the differences in the protein expression profiles in the sera of individuals in the cold exposure-induced myocardial injury group and the control group. Specifically, use a protein detection kit (4A Biotech Co., Ltd., China) to detect the protein expression levels of the blood samples.

[0059] 1. The test process is as follows:

[0060] Sample preparation:

[0061] 1) Serum: The whole blood sample is placed at room temperature for 1 hour or overnight at 2 - 8°C, then centrifuged at 2 - 8°C and 1000×g for 20 minutes, and the supernatant can be used for detection. The tube for collecting blood should be a disposable endotoxin-free tube.

[0062] 2) Plasma: EDTA-Na2 is recommended as the anticoagulant. After sample collection, centrifuge at 1000×g for 15 minutes at 2-8°C within 30 minutes, and take the supernatant for detection. Avoid using hemolyzed and hyperlipidemic samples.

[0063] 2. Preparation before detection:

[0064] 1) Take out the kit from the refrigerator 20 minutes in advance and equilibrate it to room temperature. Turn on the microplate reader 15 minutes in advance to preheat.

[0065] 2) Washing solution: Dilute the concentrated washing solution with double-distilled water (1:24).

[0066] 3) Standard working solution: Centrifuge the standard at 10000×g for 1 minute, add 1.0 mL of the standard and sample diluent to the lyophilized standard, tighten the tube cap, let it stand for 10 minutes, invert it several times up and down, and after it is fully dissolved, gently mix it to prepare a 25 ng / mL standard working solution. Then perform serial dilutions as needed.

[0067] 4) Enzyme conjugate working solution: The HRP enzyme conjugate is HRP enzyme-conjugated avidin. Calculate the required amount for the current experiment before the experiment, and actually prepare 100 - 200 μL more. 15 minutes before use, centrifuge the concentrated HRP enzyme conjugate at 800×g for 1 minute, and dilute the 100× concentrated HRP enzyme conjugate to 1× working concentration with the enzyme conjugate diluent.

[0068] 3. Operating steps:

[0069] 1) Add the standard working solution to the first two columns of wells on the microplate in sequence. Add two wells side by side for each concentration of the working solution, 50 μL per well. Add the test samples to the other wells, 50 μL per well. Immediately add 50 μL of the biotinylated antibody working solution to each well, cover the microplate with a film, and incubate at 37°C for 90 minutes.

[0070] 2) Drain the liquid in the wells, add 350 μL of the washing solution to each well, soak for 1 - 2 minutes, aspirate or shake off the liquid in the microplate, and pat it dry on thick absorbent paper. Repeat this washing step 3 times.

[0071] 3) Add 100 μL of the enzyme conjugate working solution to each well, cover with a film, and incubate at 37°C for 30 minutes.

[0072] 4) Discard the liquid in the wells, drain, wash the plate 5 times, and the method is the same as in step 2.

[0073] 5) Add 90 μL of the substrate solution to each well, cover the microplate with a film, and incubate at 37°C in the dark for about 15 minutes.

[0074] 6) Add 50 μL of the stop solution to each well to terminate the reaction.

[0075] 7) Immediately measure the optical density of each well at a wavelength of 450 nm using an enzyme-linked immunosorbent assay (ELISA) reader.

[0076] Through this step, the protein expression levels of MFN2, PACS2, FUNDC1, FIS1, DRP1, and TOM40 in the subject can be obtained.

[0077] S3. Obtain the circulatory physiological parameters of the subject

[0078] For the circulatory physiological parameters, in this embodiment, the following circulatory physiological parameters are screened to determine which circulatory physiological parameters are closely related to myocardial injury caused by cold exposure, including the blood pressure variability, blood pressure load value, heart rate, blood pressure, ejection fraction, and stroke volume of the subject; the test procedure is as follows:

[0079] At room temperature in the resting state, measure the blood pressure variability, blood pressure load value, heart rate, blood pressure, ejection fraction, and stroke volume of the subject. The room temperature in this embodiment is 23 ± 2 °C, and the resting state means that the subject does not perform physical activities 12 hours before the measurement and does not drink alcohol, caffeine, or smoke at least 5 hours before the measurement.

[0080] For the ejection fraction and stroke volume, use an echocardiogram machine (Philips, EPIQ 5, USA) for detection, and obtain data by taking the average of 5 consecutive measurements.

[0081] For the blood pressure variability, blood pressure load value, heart rate, and blood pressure, use a 24-hour ambulatory blood pressure monitoring device (Omron, HEM-6160, Japan). Place the device cuff on the right upper arm in the morning, and remove it and read the data after 24 hours of complete recording. All subjects are required to keep their limbs still during each measurement and carry out activities according to their normal physiological schedule. The daytime is defined as 6:00 to 22:00 on the same day, and the nighttime is defined as 22:00 to 6:00 the next day. The recorder measures the blood pressure every 30 minutes during the day and every 60 minutes at night. The blood pressure and heart rate are calculated by taking the average of the measurements throughout the day.

[0082] The baseline blood pressure variability is calculated using the mean real variability index, and the formula is:

[0083]

[0084] where K ranges from 1 to N, N represents the number of valid blood pressure measurements in the data corresponding to a given subject, and BP represents the measured blood pressure value.

[0085] The blood pressure load value refers to the ratio of the total number of blood pressure measurements exceeding the normal value within a certain period of time, where the normal blood pressure value is defined as daytime blood pressure < 135 / 85 mmHg and nighttime blood pressure < 120 / 70 mmHg.

[0086] S4. Obtaining other physiological parameters of the subject

[0087] Other physiological parameters included blood oxygen saturation and core body temperature. The core body temperature was measured using an ear thermometer (Philips, TH889S, USA), and the oxygen saturation was measured using a finger pulse oxygen clamp (Philips, DH18, USA).

[0088] In a specific implementation, steps S1-S4 are performed in no particular order.

[0089] S5. Obtain high-sensitivity cardiac troponin I from the subjects’ plasma and identify the presence of myocardial damage;

[0090] As a regulatory protein unique to myocardial tissue, myocardial troponin I (cTnI) plays a key role in myocardial contraction. It achieves its function by inhibiting the binding of myosin to actin. As one of the most sensitive and specific serum markers of myocardial cell injury, cTnI is widely used in the diagnosis of acute myocardial infarction in clinical practice due to its clear diagnostic threshold, wide window period and rapid detection speed.

[0091] In the specific implementation process, the EILSA assay kit (ZC-35149) was used to detect cardiac hypersensitive troponin I in human plasma. According to the instructions of the kit, 100 μl of standard or plasma sample to be tested was first added to each well, and then the kit was equilibrated at room temperature for 30 minutes. Next, the required strips were taken out of the aluminum foil bag. Standard wells and sample wells were set up, and 50 μl of different concentrations of standard were added to the standard wells. 50 μL of the sample to be tested was added to the sample wells, while nothing was added to the blank wells. In addition to the blank wells, 100 μL of HRP-labeled detection antibody was added to each well of the standard well and the sample well. The reaction wells were sealed with a sealing film and then incubated in a water bath or incubator at 37°C for 60 minutes. After that, the liquid was discarded and patted dry with absorbent paper. Each well was filled with washing solution, left to stand for 1 minute, and then the washing solution was shaken off, and patted dry again with absorbent paper, and this washing step was repeated 5 times. Substrate was added to each well, and then incubated at 37°C in the dark for 15 minutes. Finally, 50 μL of stop solution was added to each well, and the OD value of each well was measured at a wavelength of 450 nm within 15 minutes.

[0092] Myocardial injury was considered to be present if any of the following conditions occurred: (1) the ejection fraction of the heart ultrasound decreased by more than 5% after exposure to cold environment compared with the baseline level before exposure; (2) ischemic changes were found in electrocardiogram; (3) clinical symptoms such as chest tightness, chest pain, and shortness of breath after activity occurred; (4) serum myocardial injury markers exceeded the upper limit of normal reference values. All subjects were divided into a cold exposure-induced myocardial injury group and a control group.

[0093] S6. Perform statistical analysis on the demographic parameters of the subjects, the expression levels of the subjects' mitochondrial-associated endoplasmic reticulum membrane proteins, the circulatory physiological parameters of the subjects, and the other physiological parameters of the subjects using multivariate logistic regression to construct an evaluation model for cold exposure-induced myocardial injury.

[0094] In a specific embodiment, statistical software SPSS 27.0 and R language (R4.3.3) are used for statistical processing to statistically analyze the combined molecular biology indicators and circulatory physiological parameters to evaluate cold exposure-induced myocardial injury. In this analysis, the cold exposure-induced myocardial injury group and the control group are defined. Covariates are used to adjust confounding factors in the multivariate logistic regression. The Kolmogorov-Smirnov test is used to test the normal distribution of continuous variables. Variables with a normal distribution are expressed as mean ± standard deviation, and the independent sample t-test is used for comparison between groups. Data with a non-normal distribution are expressed as median (interquartile range), and the Mann-Whitney U test is used for comparison between groups of non-normally distributed data. The chi-square test is used for comparison of categorical variables between groups, and P < 0.05 is considered statistically significant. The receiver operating characteristic curve is used to determine the diagnostic efficacy of positive indicators for endpoint events. Correlation curve analysis is used to analyze the degree of correlation between positive indicators and cTnI. A nomogram is constructed to build an evaluation model for cold exposure-induced myocardial injury.

[0095] Through statistical analysis, it is found that there are no statistical differences in demographic parameters (including age, gender, body mass index, and cold region exposure time), some circulatory physiological parameters (heart rate, blood pressure, ejection fraction, and stroke volume), and other physiological parameters (oxygen saturation and core body temperature) between the cold exposure-induced myocardial injury group and the control group, as shown in Table 1. The above statistical parameters were finally not included in this cold exposure-induced myocardial injury evaluation model after being verified by logistic regression.

[0096]

[0097] As Figure 2 shown, the difference in the protein expression profiles in the sera of the two groups of subjects was analyzed using proteomic sequencing technology (Blast2GO V1.4.4, GeneChem Co., Ltd.), and it can be observed that the expression level of the mitochondrial-associated endoplasmic reticulum membrane protein MFN2 in individuals in the cold exposure-induced myocardial injury group was significantly lower than that in the control group (FoldChange ≥ 2.0, P < 0.05). Quantitative analysis was performed using a protein detection kit, and the results are as Figures 3A - 3FAs shown, the relative expression level of MFN2 protein in the group with myocardial injury caused by cold exposure was significantly decreased, while the relative expression levels of PACS2, FUNDC1, FIS1, DRP1, and TOM40 did not change significantly. At the same time, 20 patients with coronary heart disease, valvular heart disease, and cardiomyopathy who met the diagnostic criteria for myocardial injury were selected as controls, as Figure 4 shown. The analysis results showed that the content of MFN2 in the plasma of the subjects in the group with myocardial injury caused by cold exposure was significantly lower than that of the control group, while there was no significant difference in the content of MFN2 in the plasma of the subjects in the coronary heart disease, valvular heart disease, and cardiomyopathy groups compared with the control group. This indicates that MFN2 may be a specific molecular biomarker for myocardial injury caused by cold exposure. MFN2 protein is one of the molecules highly enriched in the mitochondrial and endoplasmic reticulum membranes, and it plays a key role in biological functions such as regulating calcium signaling, coping with endoplasmic reticulum stress, and mitochondrial damage. Supplementing MFN2 protein can promote the recovery of mitophagy and the remodeling of energy metabolism, protect the myocardium damaged in a cold environment, help maintain the function of the circulatory system, and promote adaptation to a cold environment.

[0098] Among the circulatory physiological parameters measured in the subjects, blood pressure variability and blood pressure load value were closely related to myocardial injury under cold exposure conditions, as Figure 5 shown. The blood pressure variability in the group with myocardial injury caused by cold exposure was significantly higher than that of the control group, while there was no significant difference in blood pressure variability in the coronary heart disease, valvular heart disease, and cardiomyopathy groups compared with the control group. As Figure 6 shown, the blood pressure load value in the group with myocardial injury caused by cold exposure was significantly higher than that of the control group, while there was no significant difference in the blood pressure load value in the coronary heart disease, valvular heart disease, and cardiomyopathy groups compared with the control group. As Figure 7 、 Figure 8As shown, cTnI is a marker protein for myocardial injury. It can be seen from the figure that cTnI is positively correlated with blood pressure variability and baseline blood pressure load level. Multivariate logistic regression confirmed that the level of blood pressure variability (P < 0.001) and the level of baseline blood pressure load value (P < 0.001) can be used to evaluate myocardial injury caused by cold exposure. The mechanism is as follows: Myocardial injury caused by cold exposure is mainly due to the increase in afterload (blood pressure) caused by the excitement of the sympathetic system after exposure to a cold environment. Blood pressure variability reflects the fluctuation of blood pressure within a certain period of the body and is a non-invasive index for quantitatively evaluating cardiovascular autonomic nerve activity. The blood pressure load value is the overall ratio of the number of times the 24-hour blood pressure exceeds the normal blood pressure range, which can well reflect the state of the body's circulatory afterload. Previous studies have pointed out that compared with the simple blood pressure value, both of them have better evaluation value for target organ damage. In addition, it is worth noting that different from patients with essential hypertension, the afterload state of the subjects is closely related to cold environment exposure, has a certain fluctuation range under the change of the external environmental temperature, and usually the blood pressure level does not reach the diagnostic standard of hypertension, and it is necessary to make a distinction for this.

[0099] In a specific embodiment, the evaluation model for myocardial injury caused by cold exposure is a logistic regression binary classifier. The evaluation parameters of the evaluation model include the expression level of MFN2 protein, blood pressure variability, and blood pressure load value, and the evaluation result is whether there is myocardial injury caused by cold exposure. As Figures 9A - 9D shown, Figure 9A for the expression level of MFN2 protein in it, the area under the curve is 0.900, P < 0.001; Figure 9B for blood pressure variability in it, the area under the curve is 0.916, P < 0.001; Figure 9C for the blood pressure load value in it, the area under the curve is 0.909, P < 0.001, indicating that it has evaluation value for myocardial injury caused by cold exposure; Figure 9D for the combined evaluation of the three indicators in it, the area under the curve is 0.983, P < 0.001, indicating that the combined evaluation of the three indicators proposed by the present invention has good accuracy and efficacy. In addition, any 3 statistical variables are selected to construct an evaluation model. After comparing the area under the curve of the combined prediction of other 15 model indicators, it is found that the evaluation model using the expression level of MFN2 protein, blood pressure variability, and blood pressure load value has the highest evaluation accuracy and the best evaluation efficacy. See Table 2 for details.

[0100]

[0101] Using R language software, a nomogram model was constructed based on the data of MFN2 protein expression, blood pressure variability, and blood pressure load value to evaluate myocardial injury caused by cold exposure. According to the specific values of the three variables, the scores of each variable were calculated separately. Subsequently, the scores of the three variables were added together to obtain a total score, corresponding to the probability of the occurrence of clinical endpoint events. Specifically, within a specific range, such as Figure 10 shown, when the relative expression level of MFN2 protein is in the range of 0.6 - 2.1, the blood pressure variability is in the range of 8 - 36, and the blood pressure load value is in the range of 0 - 0.5, for every 1 unit decrease in the expression level of MFN2 protein, the score of this index will increase by 66.67 points; for every 1 unit increase in blood pressure variability, the score of this index will increase by 3.81 points; for every 1 unit increase in blood pressure load value, the score of this index will increase by 144.00 points. When the total score is lower than 131.20 points, the occurrence probability of myocardial injury caused by cold exposure is less than 0.1, that is, less than 10%; when the total score is between 131.20 and 143.20 points, the occurrence probability varies between 0.1 and 0.3, that is, the occurrence risk is 10% - 30%; when the total score is between 143.20 and 151.20 points, the occurrence probability varies between 0.3 and 0.5, that is, the occurrence risk is 30% - 50%; when the total score is between 151.20 and 159.20 points, the occurrence probability varies between 0.5 and 0.7, that is, the occurrence risk is 50% - 70%; when the total score is between 159.20 and 171.20 points, the occurrence probability varies between 0.7 and 0.9, that is, the occurrence risk is 70% - 90%; when the total score exceeds 171.20 points, the occurrence probability of myocardial injury caused by cold exposure exceeds 0.9, that is, the occurrence risk exceeds 90%. In this way, the occurrence situation of myocardial injury caused by cold exposure can be analyzed. As Figure 11 shown, the high goodness of fit of the model was verified by the Hosmer - Lemeshow test (P > 0.05).

[0102] As Figure 12 shown, another 10 subjects were taken as the validation set (the specific situation is the same as described above), and the standard described above was used to determine whether the subjects had myocardial injury. According to the requirements of the model constructed by the present invention, the data of MFN2 protein expression, blood pressure variability, and blood pressure load value were measured respectively. The area under the curve of the combined evaluation of the three indicators was 1.000, P < 0.001, and the evaluation efficiency was good. The specific data were brought into the constructed model to predict the incidence rate of myocardial injury caused by cold exposure in these subjects respectively, as shown in Table 3 specifically.

[0103]

[0104] In some embodiments, an evaluation method for myocardial injury caused by cold exposure based on cyclic physiological parameters is further provided, including the following steps:

[0105] Step 1. Obtain the MFN2 protein expression level of the person to be evaluated

[0106] Use the blood of the subject to obtain the MFN2 protein expression level of the subject through a molecular detection kit. The specific operation is as described above.

[0107] Step 2. Measure the blood pressure variability of the person to be evaluated

[0108] The specific operation is as described above.

[0109] Step 3. Measure the blood pressure load value of the person to be evaluated

[0110] The specific operation is as described above.

[0111] In a specific embodiment, the execution order of Step 1, Step 2, and Step 3 is not sequential.

[0112] Step 4. Input the MFN2 protein expression level, blood pressure variability, and blood pressure load value into the cold exposure-induced myocardial injury assessment model to evaluate the occurrence of myocardial injury in the person to be evaluated in a cold environment.

[0113] Input the MFN2 protein expression level, blood pressure variability, and blood pressure load value of the person to be evaluated into the cold exposure-induced myocardial injury assessment model, and the possibility of circulatory dysfunction and acute cardiovascular events occurring after the person to be evaluated is exposed to a cold environment can be obtained. For those with a low incidence of myocardial injury indicated by the evaluation results, the possibility of circulatory dysfunction and acute cardiovascular events is relatively low; for those with a high incidence of myocardial injury indicated by the evaluation results, the possibility of circulatory dysfunction and acute cardiovascular events is relatively high. This model is applicable to cold environments below -20 °C.

[0114] In some embodiments, a cold exposure-induced myocardial injury assessment system is also provided. The system includes:

[0115] An MFN2 protein expression level detection device for obtaining the MFN2 protein expression level of the person to be evaluated; in a specific embodiment, the protein expression level of the blood sample of the person to be evaluated is mainly detected through a protein detection kit.

[0116] A blood pressure variability and blood pressure load value measurement device for measuring the blood pressure variability and blood pressure load value of the person to be evaluated; in a specific embodiment, the measurement of the person to be evaluated is mainly carried out through a 24-hour ambulatory blood pressure monitoring device.

[0117] A cold exposure-induced myocardial injury assessment device for evaluating the occurrence of myocardial injury in the person to be evaluated in a cold environment according to the MFN2 protein expression level, blood pressure variability, and blood pressure load value of the person to be evaluated, using the cold exposure-induced myocardial injury assessment model.

[0118] Through the technical solution provided by this embodiment, by combining the molecular biological indexes of the human body with the cyclic physiological parameters to evaluate the occurrence of myocardial injury caused by cold environment exposure, it is possible to identify individuals who are prone to circulatory dysfunction and acute cardiovascular events before physical activities in a cold environment, which is of great significance for ensuring the personal safety of personnel operating in cold regions and improving mission effectiveness.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and the description of the present invention.

Claims

1. A method for constructing a model for evaluating myocardial injury caused by cold exposure, characterized in that The following steps are involved: S1. Data acquisition: Obtain the demographic parameters of the subjects; obtain the expression levels of mitochondrial-related endoplasmic reticulum membrane proteins of the subjects; Obtaining the subject's circulatory physiological parameters; obtaining the subject's other physiological parameters; obtaining the subject's plasma myocardial high-sensitivity troponin I and identifying whether there is myocardial damage; S2. Risk parameter screening: The demographic parameters of the subjects, the expression of mitochondrial-related endoplasmic reticulum membrane proteins, the circulatory physiological parameters, and other physiological parameters of the subjects were used as evaluation parameters to screen risk parameters associated with myocardial injury caused by cold exposure; S3. Regression analysis: The risk parameters obtained by screening were statistically analyzed using multivariate logistic regression to construct an assessment model for myocardial damage caused by cold exposure.

2. The method for constructing a cold exposure-induced myocardial injury assessment model according to claim 1, characterized in that: The risk parameters are the expression level of mitochondrial-related endoplasmic reticulum membrane protein MFN2, the circulatory physiological parameters blood pressure variability and blood pressure load value.

3. The method for constructing a cold exposure-induced myocardial injury assessment model according to claim 1, characterized in that Also included is S4 showing the calculation steps: A nomogram is used to display the relationship between the risk factor data and the data after the regression analysis; and the score of each variable is calculated according to the specific values ​​of the three variables; The scores of the three variables are added together to obtain the total score, which corresponds to the probability of occurrence of a clinical endpoint event.

4. The method for constructing a cold exposure-induced myocardial injury assessment model according to claim 3, characterized in that The calculation method in S4 is: First, the blood pressure load value and blood pressure variability, i.e., the range of physiological parameters of MFN2 protein, were set. The blood pressure load value range was 0-0.5, the blood pressure variability range was 8-36, and the relative expression range of MFN2 protein was 0.6-2.

1. For every 1-unit decrease in MFN2 protein expression, the index score would increase by 66.67 points. For every 1-unit increase in blood pressure variability, the index score would increase by 3.81 points. For every 1-unit increase in blood pressure load value, the index score would increase by 144.00 points. When the total score was lower than 131.20 points, The probability of myocardial injury caused by cold exposure is less than 10%; when the total score is between 131.20 and 143.20 points, the probability of occurrence is 10%-30%; when the total score is between 143.20 and 151.20 points, the probability of occurrence is 30%-50%; when the total score is between 151.20 and 159.20 points, the probability of occurrence is 50%-70%; when the total score is between 159.20 and 171.20 points, the probability of occurrence is 70%-90%; when the total score exceeds 171.20 points, the probability of myocardial injury caused by cold exposure exceeds 90%.

5. A model for evaluating myocardial damage caused by cold exposure, characterized in that The method is constructed by any one of claims 1 to 4.

6. A method for analyzing data on myocardial damage caused by cold exposure, characterized in that The following steps are involved: Obtaining the MFN2 protein expression level of the person to be evaluated; Measuring blood pressure variability in the person being evaluated; Measure the blood pressure load value of the person to be evaluated; The MFN2 protein expression, blood pressure variability and blood pressure load values ​​are input into the cold exposure-induced myocardial injury assessment model of claim 5, and the myocardial injury data of the person to be assessed in a cold environment are analyzed.

7. A system for evaluating myocardial damage caused by cold exposure, characterized in that include: An MFN2 protein expression detection device, used to obtain the MFN2 protein expression level of the person to be evaluated; A blood pressure variability measuring device for measuring the blood pressure variability of the person to be evaluated; A blood pressure load value measuring device, used to measure the blood pressure load value of the person to be evaluated; The cold exposure-induced myocardial injury assessment device is used to assess the occurrence of myocardial injury in a person to be assessed in a cold environment based on the MFN2 protein expression, blood pressure variability and blood pressure load value of the person to be assessed, using the cold exposure-induced myocardial injury assessment model described in claim 5.

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