死后间隔时间推断的新研究
发布时间：2018-07-31 18:17
【摘要】： 死后间隔时间(postmortem interval，PMI)或称死亡时间推断(estimation of time since death，ETSD)是法医病理学实际检案及研究工作的重点和难点之一。长期以来，国内外的学者们已采用多种技术与方法尝试PMI的推断，尤其是早期PMI的推断，如利用死后各种尸体现象、肌肉超生反应、玻璃体液钾离子浓度、死后血液的生化变化等，但其准确性常受到外界各种因素的影响，往往误差较大。至目前为止，尚无公认的简易实用、准确可靠的推断方法，尤其是中晚期PMI的推断方法更不尽人意。因此，本课题研究大鼠死后皮下肌肉组织电阻抗幅值和相位角的变化规律，以探讨生物电阻抗推断中晚期PMI的价值，试图发展一种简单方便、准确可靠的推断中晚期PMI的新方法；选择前期研究尚未用过的分析指标——headDNA％，应用单细胞凝胶电泳技术检测大鼠死后脑、骨髓细胞核DNA降解随PMI的变化规律，以探索单细胞凝胶电泳技术推断早期PMI的新参数。 第一部分大鼠死后皮下肌肉组织电阻抗幅值和相位角变化推断死后间隔时间的实验研究 【目的】研究大鼠死后皮下肌肉组织电阻抗幅值和相位角的变化规律，探讨生物电阻抗技术推断中晚期PMI的价值，试图发展一种简单方便、准确可靠的推断中晚期PMI的新方法。同时从肌肉组织形态学的角度初步分析了电阻抗幅值变化趋势产生的机制。 【方法】取Wistar健康成年大鼠20只，分成4个实验组，每组5只，分别对应于四个不同的测量温度(9±1℃、14±1℃、16±1℃、19±1℃)。用颈椎脱臼的方式处死动物，将电极插入大腿部肌肉并固定。迅速将动物置于设定温度的恒温培养箱或冰箱中，利用四电极阻抗测量系统测量大鼠死后皮下肌肉组织电阻抗幅值和相位角。自死后0h开始，每隔3h记录一次电阻抗数据(夜间关机时除外)和环境温度。当实验时间足够长时(阻抗下降到原始阻抗的70％左右或15天以上)便可停止实验。再用Excel对所得的离散阻抗数据进行简单的均值、方差分析，用MATLAB对阻抗数据进行相关分析和直线拟合并作图、计算相关系数。 取前述4只实验大鼠(1只为死前对照组，3只为死后实验组)，分别于死后12h、24h和72h在大鼠电阻抗测量部位皮下肌肉组织取材、常规制片、HE染色后，在光镜下观察组织形态学变化，并与其电阻抗的变化进行对比分析。 【结果】 1．所有死亡大鼠皮下肌肉组织的电阻抗幅值都呈现出相似的先升后降的变化趋势，且中、长期的下降部分有一定的线性变化趋势。死亡初期(PMI=1～4天)电阻抗幅值迅速上升，达峰值后随着时间的推移，呈线性下降趋势(PMI=4～15天)，最终趋于平坦。 2．所有死亡大鼠皮下肌肉组织的电阻抗相位角没有相似的变化规律，其变化杂乱无章。 3．相对电阻抗可以一定程度上消去不同大鼠由于初值的差异造成的特异性，而且同一温度组不同大鼠之间的离散性较绝对电阻抗小。 4．温度越高绝对电阻抗或相对电阻抗上升得越快，下降得亦更快；温度越低绝对电阻抗或相对电阻抗上升得越缓慢，下降得更缓慢。绝对电阻抗或相对电阻抗下降段斜率亦与温度的变化呈正相关关系。 5．各温度组下降段斜率与PMI的相关系数均大于0.97，表明各温度组下降段与PMI之间的相关性很高，因此，有可能利用这一线性关系推断中、晚期PMI。 6．大鼠死前核未见改变，肌束横纹清晰；死后12h，表层少数肌束肿胀，肌丝多数呈细颗粒状或匀质状，横纹消失；死后72h，较多见肌纤维肿胀、颗粒样变、横纹消失。随着PMI推移逐步产生细胞膜自溶裂解过程，组织的导电性增加，因而表现为电阻抗不断下降的结果。 【结论】 1．大鼠死后皮下肌肉组织电阻抗幅值随时间的推移呈现先上升后下降的变化趋势，并且下降部分的电阻抗幅值变化和PMI之间存在线性关系。在测量环境相似的条件下，电阻抗变化也相似。 2．环境温度是影响电阻抗幅值最主要的参数，且环境温度越高其变化速度越快。因此，电阻抗的测量还要注意其适用的温度范围，温度过高和过低都不适合使用。 3．测量电阻抗幅值时，将绝对电阻抗转换成相对电阻抗，更能反映电阻抗变化的客观规律。 4．电阻抗下降段斜率与温度的变化呈正相关关系，且在不同环境温度时，下降段斜率与PMI的相关性都较高。如果找出下降段起点、峰值、斜率这三者之间的确定关系，就可利用下降段的线性关系为推断中晚期PMI提供一定的判断依据。 5．由于电阻抗相位角受环境因素的影响很大，目前还不能用于PMI的推断。 6．通过对电阻抗变化趋势产生的机制从组织形态变化方面进行的初步探讨，得出了和细胞生物学理论解释相一致的结果。 7．相对于其它PMI推断技术而言，电阻抗法具有测量简单方便、准确可靠的优点，但是鉴于目前的检测水平和环境因素的限制，能否应用于实际情况，发展成为一种新型的PMI推断技术，还需要做进一步的研究和探讨。 第二部分单细胞凝胶电泳检测大鼠死后脑、骨髓细胞核DNA降解推断死后间隔时间的研究 【目的】应用单细胞凝胶电泳技术(Single-cell gel electrophoresis，SCGE)直接检测大鼠死后不同温度下脑、骨髓细胞核DNA降解的情况，选择既往研究尚未用过的参数headDNA％分析不同温度下DNA降解的程度随PMI变化的规律，建立两者的回归方程，并与标准指标尾长(TL)、Oliver尾距(TM)进行对比，以期为该方法推断早期PMI探索新的参数。 【方法】以颈髓离断法处死大鼠，保存在温度分别控制在10℃±1℃或20℃±1℃的实验环境下，在大鼠死后0～40h内，，每隔4h，分别对脑组织和骨髓取材，并制作单细胞悬液；然后进行单细胞凝胶电泳；在荧光显微镜下观察并拍照。所摄图像用CASP0.22彗星图像分析软件进行检测，选择既往研究尚未用过的参数headDNA％分析不同温度下DNA降解的程度随PMI变化的规律，用SAS8.0和SPSS12.0分析软件进行统计学分析，建立两者的回归方程，并与标准指标尾长(TL)、Oliver尾距(TM)的分析结果进行对比。同时，依据建立的方程和headDNA％估计值95％可信区间计算公式反推PMI范围的计算公式。 【结果】 1．大鼠死后，脑细胞、骨髓细胞在电泳图上出现了不同程度的彗星形拖尾； 2．大鼠死后早期PMI内，不论在10℃还是20℃下，脑、骨髓细胞核HeadDNA％的下降与PMI之间存在着良好的线性关系，建立了四个线性回归方程，其确定系数均较高，可用于早期PMI推断； 3．死后细胞核HeadDNA％的下降受环境温度、组织种类的影响； 4．建立了由已知HeadDNA％值反推PMI范围的计算公式：如脑组织在20℃下，据某已知HeadDNA％值反推PMI范围的计算公式： timel=(86.83-DNA_(已知))／1.9634 time2=(99.27-DNA_(已知))／1.9634 5．选用的参数HeadDNA％较前期研究惯用的标准指标TL、TM与PMI的线性回归方程拟合较理想； 6．脑组织、骨髓组织分别用三种参数与PMI拟合的线性回归分析，前者的确定系数较后者高。 【结论】 1．单细胞凝胶电泳技术可应用与早期PMI的推断； 2．环境温度和组织差异明显影响死后核DNA的降解； 3．新参数HeadDNA％较前期研究惯用的标准指标TL、TM推断PMI的价值更高，但其可靠性有待于今后进一步的研究，尤其是人体材料研究的验证； 4．由已知HeadDNA％值可反推PMI的范围； 5．脑组织是较骨髓组织更为理想的备选检材。
[Abstract]:The postmortem interval time (postmortem interval, PMI) or death time inference (estimation of time since death, ETSD) is one of the key and difficult points in the actual forensic pathology examination and research work. For a long time, scholars at home and abroad have adopted a variety of techniques and methods to try the inference of PMI, especially early PMI inference, such as the use of death. All kinds of postmortem phenomena, muscle excess reaction, concentration of potassium ion in vitreous fluid, biochemical changes in blood after death, but their accuracy is often influenced by various external factors and often has great errors. Up to now, there is no recognized simple practical, accurate and reliable inference method, especially in the middle and late PMI. This study studies the variation of the amplitude and phase angle of the electrical impedance of the subcutaneous muscle tissue after the death of the rat, in order to explore the value of the advanced PMI in the early stage of the bioelectrical impedance inference, and to try to develop a simple, accurate and reliable new method to infer the middle and late PMI, and choose the unused analysis index of the previous study, headDNA%, to apply the single fine. Cell gel electrophoresis was used to detect the rat's dead brain, and the DNA degradation of the nucleus of bone marrow was changed with PMI, and the new parameters of early PMI were deduced by single cell gel electrophoresis.
Part one: inferring postmortem interval from the changes of electrical impedance and phase angle in rat subcutaneous muscle tissue after death
[Objective] to study the changes of the amplitude and phase angle of the electrical impedance of the subcutaneous muscle tissue of the rat after death, and to explore the value of the advanced PMI by bioelectrical impedance technique, and try to develop a simple, accurate and reliable new method to infer the middle and late PMI. The mechanism of the trend.
[Methods] 20 healthy adult rats were divided into 4 experimental groups, which were divided into 4 experimental groups, with 5 rats in each group, corresponding to four different measuring temperatures (9 + 1, 14 + 1, 16 + 1, 19 + 1). The animals were killed by the dislocated cervical vertebra, and the electrodes were inserted into the thigh muscles and fixed. The animals were quickly placed in a thermostat incubator or refrigerator at setting temperature. A four electrode impedance measurement system was used to measure the amplitude and phase angle of the electrical impedance of the subcutaneously muscle tissue of the rat after death. From 0h after death, the electrical impedance data was recorded every 3H (except at night) and the ambient temperature. When the experiment time was long enough (the impedance dropped to about 70% or more of the original impedance), the experiment could be stopped. Then Exce could be stopped. The discrete impedance data obtained by L are simple mean, variance analysis, correlation analysis of impedance data by MATLAB and the drawing of straight line, and the correlation coefficient is calculated.
The 4 experimental rats (1 for pre death control group and 3 for the postmortem group) were obtained after death, 12h, 24h and 72h were harvested subcutaneously in the electrical impedance measurement site of rats. The changes of histomorphology were observed under the light microscope, and the changes of electrical impedance were compared and analyzed after HE staining.
[results]
1. the amplitudes of the electrical impedance of the subcutaneous muscle tissues of all the dead rats showed a similar trend in the first rise and then descending. In the meantime, the long-term descending part had a certain linear trend. The amplitude of the electrical impedance increased rapidly in the early period of death (PMI=1 to 4 days), and then a linear descending trend (PMI=4 to 15 days) with the passage of time. It tends to be flat.
2. the electrical impedance phase angle of subcutaneous muscle tissue of all the dead rats did not change in a similar way.
3. relative electrical impedance can eliminate the specificity of different rats due to the difference of initial values, and the dispersion of the rats in the same temperature group is smaller than that of the absolute impedance.
4. the higher the temperature is, the faster the absolute electrical impedance and relative electrical impedance rise and the faster the decrease. The lower the temperature is, the slower the absolute electrical impedance or relative electrical impedance rises, and the decrease is more slow. The slope of absolute electrical impedance or relative impedance is also positively related to the change of temperature.
5. the correlation coefficient of the slope of each temperature group and the PMI is more than 0.97, indicating that the correlation between the decrease segments of each temperature group and the PMI is very high. Therefore, it is possible to use this linear relationship to deduce the late PMI..
In the 6. rats, the nucleus of the 6. rats was not changed and the transverse lines were clear. After death, a few muscle bundles were swollen. Most of the muscle fibers were fine grainy or homogeneous, and the transverse lines disappeared. After death, the muscle fibers swelled, granulated, and the transverse lines disappeared. As PMI progressively produced the process of cell membrane self dissolution and cracking, the electrical conductivity of tissue increased and thus manifested as 72h. The result of constant decrease in electrical impedance.
[Conclusion]
After the death of the 1. rats, the amplitude of the electrical impedance of the subcutaneous muscles increased first and then decreased with time, and there was a linear relationship between the amplitude of the electrical impedance of the descending part and the PMI. The electrical impedance changes were similar under the condition of similar measurement environment.
2. environment temperature is the most important parameter that affects the amplitude of electrical impedance, and the higher the environment temperature is, the faster the change speed. Therefore, the measurement of electrical impedance should pay attention to its applicable temperature range, both too high temperature and too low are not suitable for use.
3. when measuring the magnitude of the electrical impedance, the absolute impedance will be converted to the relative impedance, which can better reflect the objective law of the change of electrical impedance.
4. the slope of the descending section of electrical impedance is positively correlated with the change of temperature, and the correlation between the slope of the descending section and the PMI is higher at different ambient temperatures. If we find the relationship between the starting point, the peak and the slope of the descending section, the linear relation of the descending section can be used to provide a certain basis for the inference of the late PMI.
5. because electrical impedance phase angle is greatly influenced by environmental factors, it can not be used for PMI inference at present.
6. through the preliminary discussion of the mechanism of the change of electrical impedance from the change of tissue morphology, the result is consistent with the theoretical explanation of cell biology.
7. compared with other PMI inference techniques, electrical impedance method has the advantages of simple and convenient measurement and accurate and reliable. However, in view of the current level of detection and the restriction of environmental factors, it is necessary to study and discuss whether it can be applied to the actual situation and develop into a new type of PMI inference technology.
In the second part, single cell gel electrophoresis was used to detect the postmortem interval of DNA in rats.
[Objective] to use Single-cell gel electrophoresis (SCGE) to directly detect the DNA degradation of brain and bone marrow nuclei at different temperatures after death in rats, and select the unused parameter headDNA% to analyze the regularity of the degree of DNA degradation with PMI at different temperatures at different temperatures and establish the regression equations. It is compared with the standard index tail length (TL) and Oliver trailing distance (TM), in order to infer new parameters for early PMI by this method.
[Methods] the rats were killed by the cervical spinal cord disconnection, and stored in the experimental environment under the temperature of 10, 1 or 20 and 20 C, respectively, in 0 ~ 40H after the death of the rat, every 4h, respectively, of the brain tissue and bone marrow, and the single cell suspension was made, then the single cell gel electrophoresis was carried out, and the photo was observed and photographed under the fluorescence microscope. CASP0.22 comet image analysis software was used to detect the changes of the degree of DNA degradation at different temperatures at different temperatures. The regression equation was established by SAS8.0 and SPSS12.0 analysis software, and the analysis of the tail length of the standard index (TL) and the tail distance of Oliver (TM) was analyzed with the SAS8.0 and SPSS12.0 analysis software. At the same time, the calculation formula of PMI range is deduced from the established equation and the 95% confidence interval formula of headDNA% estimation.
[results]
1. after the death of the rats, the brain cells and bone marrow cells showed different comet shaped tails in the electrophoregram.
In the early postmortem PMI of 2. rats, there was a good linear relationship between the decrease of HeadDNA% in the brain and the nucleus of bone marrow, no matter at 10 or 20 C, and four linear regression equations were established. The coefficients were all high, which could be used for early PMI inference.
3. the decrease of HeadDNA% in nuclei after death was influenced by environmental temperature and tissue types.
4. Establish a formula for estimating the PMI range from the known head DNA% value. For example, the formula for estimating the PMI range from the known head DNA% value in brain tissue at 20 C is established.
Timel= (86.83-DNA_ (known)) / 1.9634
Time2= (99.27-DNA_ (known)) / 1.9634
5. the parameter HeadDNA% selected is better than the standard regression equation TL used in previous studies, and the linear regression equation between TM and PMI.
6. the linear regression analysis of brain tissue and bone marrow tissue was fitted with three parameters and PMI. The former had higher coefficient of determination than the latter.
[Conclusion]
1. single cell gel electrophoresis technique can be used to deduce early PMI.
2. the difference of environmental temperature and tissue significantly affected the degradation of DNA after death.
3. the new parameter HeadDNA% is compared with the standard index TL, which is used in the previous study, and TM deduce that the value of PMI is higher, but its reliability needs to be further studied in the future, especially in the research of human material.
4. the range of PMI can be pushed back by the known HeadDNA% value.
5. brain tissue is an ideal alternative material for bone marrow tissue.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2006
【分类号】：D919
本文编号：2156427
[Abstract]:The postmortem interval time (postmortem interval, PMI) or death time inference (estimation of time since death, ETSD) is one of the key and difficult points in the actual forensic pathology examination and research work. For a long time, scholars at home and abroad have adopted a variety of techniques and methods to try the inference of PMI, especially early PMI inference, such as the use of death. All kinds of postmortem phenomena, muscle excess reaction, concentration of potassium ion in vitreous fluid, biochemical changes in blood after death, but their accuracy is often influenced by various external factors and often has great errors. Up to now, there is no recognized simple practical, accurate and reliable inference method, especially in the middle and late PMI. This study studies the variation of the amplitude and phase angle of the electrical impedance of the subcutaneous muscle tissue after the death of the rat, in order to explore the value of the advanced PMI in the early stage of the bioelectrical impedance inference, and to try to develop a simple, accurate and reliable new method to infer the middle and late PMI, and choose the unused analysis index of the previous study, headDNA%, to apply the single fine. Cell gel electrophoresis was used to detect the rat's dead brain, and the DNA degradation of the nucleus of bone marrow was changed with PMI, and the new parameters of early PMI were deduced by single cell gel electrophoresis.
Part one: inferring postmortem interval from the changes of electrical impedance and phase angle in rat subcutaneous muscle tissue after death
[Objective] to study the changes of the amplitude and phase angle of the electrical impedance of the subcutaneous muscle tissue of the rat after death, and to explore the value of the advanced PMI by bioelectrical impedance technique, and try to develop a simple, accurate and reliable new method to infer the middle and late PMI. The mechanism of the trend.
[Methods] 20 healthy adult rats were divided into 4 experimental groups, which were divided into 4 experimental groups, with 5 rats in each group, corresponding to four different measuring temperatures (9 + 1, 14 + 1, 16 + 1, 19 + 1). The animals were killed by the dislocated cervical vertebra, and the electrodes were inserted into the thigh muscles and fixed. The animals were quickly placed in a thermostat incubator or refrigerator at setting temperature. A four electrode impedance measurement system was used to measure the amplitude and phase angle of the electrical impedance of the subcutaneously muscle tissue of the rat after death. From 0h after death, the electrical impedance data was recorded every 3H (except at night) and the ambient temperature. When the experiment time was long enough (the impedance dropped to about 70% or more of the original impedance), the experiment could be stopped. Then Exce could be stopped. The discrete impedance data obtained by L are simple mean, variance analysis, correlation analysis of impedance data by MATLAB and the drawing of straight line, and the correlation coefficient is calculated.
The 4 experimental rats (1 for pre death control group and 3 for the postmortem group) were obtained after death, 12h, 24h and 72h were harvested subcutaneously in the electrical impedance measurement site of rats. The changes of histomorphology were observed under the light microscope, and the changes of electrical impedance were compared and analyzed after HE staining.
[results]
1. the amplitudes of the electrical impedance of the subcutaneous muscle tissues of all the dead rats showed a similar trend in the first rise and then descending. In the meantime, the long-term descending part had a certain linear trend. The amplitude of the electrical impedance increased rapidly in the early period of death (PMI=1 to 4 days), and then a linear descending trend (PMI=4 to 15 days) with the passage of time. It tends to be flat.
2. the electrical impedance phase angle of subcutaneous muscle tissue of all the dead rats did not change in a similar way.
3. relative electrical impedance can eliminate the specificity of different rats due to the difference of initial values, and the dispersion of the rats in the same temperature group is smaller than that of the absolute impedance.
4. the higher the temperature is, the faster the absolute electrical impedance and relative electrical impedance rise and the faster the decrease. The lower the temperature is, the slower the absolute electrical impedance or relative electrical impedance rises, and the decrease is more slow. The slope of absolute electrical impedance or relative impedance is also positively related to the change of temperature.
5. the correlation coefficient of the slope of each temperature group and the PMI is more than 0.97, indicating that the correlation between the decrease segments of each temperature group and the PMI is very high. Therefore, it is possible to use this linear relationship to deduce the late PMI..
In the 6. rats, the nucleus of the 6. rats was not changed and the transverse lines were clear. After death, a few muscle bundles were swollen. Most of the muscle fibers were fine grainy or homogeneous, and the transverse lines disappeared. After death, the muscle fibers swelled, granulated, and the transverse lines disappeared. As PMI progressively produced the process of cell membrane self dissolution and cracking, the electrical conductivity of tissue increased and thus manifested as 72h. The result of constant decrease in electrical impedance.
[Conclusion]
After the death of the 1. rats, the amplitude of the electrical impedance of the subcutaneous muscles increased first and then decreased with time, and there was a linear relationship between the amplitude of the electrical impedance of the descending part and the PMI. The electrical impedance changes were similar under the condition of similar measurement environment.
2. environment temperature is the most important parameter that affects the amplitude of electrical impedance, and the higher the environment temperature is, the faster the change speed. Therefore, the measurement of electrical impedance should pay attention to its applicable temperature range, both too high temperature and too low are not suitable for use.
3. when measuring the magnitude of the electrical impedance, the absolute impedance will be converted to the relative impedance, which can better reflect the objective law of the change of electrical impedance.
4. the slope of the descending section of electrical impedance is positively correlated with the change of temperature, and the correlation between the slope of the descending section and the PMI is higher at different ambient temperatures. If we find the relationship between the starting point, the peak and the slope of the descending section, the linear relation of the descending section can be used to provide a certain basis for the inference of the late PMI.
5. because electrical impedance phase angle is greatly influenced by environmental factors, it can not be used for PMI inference at present.
6. through the preliminary discussion of the mechanism of the change of electrical impedance from the change of tissue morphology, the result is consistent with the theoretical explanation of cell biology.
7. compared with other PMI inference techniques, electrical impedance method has the advantages of simple and convenient measurement and accurate and reliable. However, in view of the current level of detection and the restriction of environmental factors, it is necessary to study and discuss whether it can be applied to the actual situation and develop into a new type of PMI inference technology.
In the second part, single cell gel electrophoresis was used to detect the postmortem interval of DNA in rats.
[Objective] to use Single-cell gel electrophoresis (SCGE) to directly detect the DNA degradation of brain and bone marrow nuclei at different temperatures after death in rats, and select the unused parameter headDNA% to analyze the regularity of the degree of DNA degradation with PMI at different temperatures at different temperatures and establish the regression equations. It is compared with the standard index tail length (TL) and Oliver trailing distance (TM), in order to infer new parameters for early PMI by this method.
[Methods] the rats were killed by the cervical spinal cord disconnection, and stored in the experimental environment under the temperature of 10, 1 or 20 and 20 C, respectively, in 0 ~ 40H after the death of the rat, every 4h, respectively, of the brain tissue and bone marrow, and the single cell suspension was made, then the single cell gel electrophoresis was carried out, and the photo was observed and photographed under the fluorescence microscope. CASP0.22 comet image analysis software was used to detect the changes of the degree of DNA degradation at different temperatures at different temperatures. The regression equation was established by SAS8.0 and SPSS12.0 analysis software, and the analysis of the tail length of the standard index (TL) and the tail distance of Oliver (TM) was analyzed with the SAS8.0 and SPSS12.0 analysis software. At the same time, the calculation formula of PMI range is deduced from the established equation and the 95% confidence interval formula of headDNA% estimation.
[results]
1. after the death of the rats, the brain cells and bone marrow cells showed different comet shaped tails in the electrophoregram.
In the early postmortem PMI of 2. rats, there was a good linear relationship between the decrease of HeadDNA% in the brain and the nucleus of bone marrow, no matter at 10 or 20 C, and four linear regression equations were established. The coefficients were all high, which could be used for early PMI inference.
3. the decrease of HeadDNA% in nuclei after death was influenced by environmental temperature and tissue types.
4. Establish a formula for estimating the PMI range from the known head DNA% value. For example, the formula for estimating the PMI range from the known head DNA% value in brain tissue at 20 C is established.
Timel= (86.83-DNA_ (known)) / 1.9634
Time2= (99.27-DNA_ (known)) / 1.9634
5. the parameter HeadDNA% selected is better than the standard regression equation TL used in previous studies, and the linear regression equation between TM and PMI.
6. the linear regression analysis of brain tissue and bone marrow tissue was fitted with three parameters and PMI. The former had higher coefficient of determination than the latter.
[Conclusion]
1. single cell gel electrophoresis technique can be used to deduce early PMI.
2. the difference of environmental temperature and tissue significantly affected the degradation of DNA after death.
3. the new parameter HeadDNA% is compared with the standard index TL, which is used in the previous study, and TM deduce that the value of PMI is higher, but its reliability needs to be further studied in the future, especially in the research of human material.
4. the range of PMI can be pushed back by the known HeadDNA% value.
5. brain tissue is an ideal alternative material for bone marrow tissue.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2006
【分类号】：D919
【引证文献】
相关期刊论文 前1条
1 文星;梁志宏;张根伟;黄岚;王忠义;;基于稳态空间分辨光谱的猪肉新鲜度检测方法[J];农业工程学报;2010年09期
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