Biomarcadores para la estimación del intervalo postmortem y la identificación de patologías en restos óseos humanos

Laburpena

an Abstract ABSTRACT Estimation of postmortem interval is an important goal in forensic medicine and continues to be one of the more difficult tasks of the forensic investigator. Actually, few accurate methods exist to determine the time since death of skeletonized human remains due to the great number of intrinsic factors that may alter the normal course of postmortem change, such as the age, sex, constitution and previous physiological and pathological states of the subject, and external factors. The purpose of this research, is to assess the utility of various biochemical parameters such as the nitrogenous bases (adenine, guanine, purines, cytosine, thymine, pyrimidines, hypoxanthine, xanthine, purine/pyrimidine ratio and pyrimidine/purine ratio), DNA and peptides of collagen type I in cortical bone for the establishment of data in a total of 80 long bones of 80 corpses (50 males, 30 females) with a mean age of 68.31 years (S.D.=18.021, range=20-97) were used. The bones were removed from the cement niches of a cemetery in Murcia (south-eastern Spain), where they had lain for between 5 and 47 years (mean time 23.83 years, S.D.=10.85). The procedure followed for the determination of nitrogenous bases, nucleic acids and peptides of Collagen Type I was the realization of HPLC-UV, fluorometry and HPLC-MS/MS respectively. Our results confirm that bone is a suitable matrix for the extraction, identification and quantification, through protocols and techniques used, of DNA, nitrogenous bases and peptides of collagen type I in a PMI between 5 and 47 years. In addition, our research shows how adenine concentrations from guanine, thymine to cytosine and purines to pyrimidines are superior higher in this PMI, as well as the establishment of significant inverse relationships between the nitrogenous bases and the peptides of collagen type I analyzed and the PMI, which follow an exponential and logarithmic decrease model, respectively. In a PMI up to 20 years the concentrations of several nitrogenous bases and the peptides of collagen type I are significantly superior to a PMI superior or equal to 20 years, furthermore, there is a significant inverse relationship between the biomolecules and these intervals, with an exponential trend. The use of the combined form of all biomarkers quantified in this research allows the correct classification of the samples in the PMI groups less than 20 years and superior than or equal to 20 years of 86.7%. Abstract In other hand, other of the problems presents in forensic medicine is the identification of the subjects, in this case forensic anthropology often uses osteobiography, which involves biological profiles based on a determination of the age, sex, constitution, pathological states and other anomalies (paleopathology) of subjects for identification purposes. The second purpose of this investigation is analyzing proteins in bone remains to search for pathological biomarkers which are closely related to several diseases. A total of 45 long bones from 45 different cadavers (29 males, 16 females) with a mean age of 66.31 years (S.D.=19.48, range 20¿97) were used. The bones were in cement niches of a cemetery in Murcia (south- eastern Spain), where they had lain for between 18 and 45 years (mean time 25.84 years, S.D.=8.91). After a specific extraction using Tris-Urea buffer, were identified using HPLC-MS/MS. Our results show that proteins resulting from tumoral diseases and bacterial and viral pathogens can be detected and identified in the skeletal remains, making them useful pathological biomarkers for constructing biological profiles. Key Words: Nitrogenous bases, DNA, Peptides of collagen type I, Bone, Postmortem interval, Identification, Pathological biomarkers, Biological profiles.