María S. Rodríguez-Calvo

Molecular genetics of sudden cardiac death

Sudden cardiac death (SCD) is one of the most common causes of death. An important number of sudden deaths, especially in the young, are due to genetic heart disorders, both with structural and arrhythmogenic abnormalities. In recent years, significant advances have been made in understanding the genetic basis of SCD. Identification of the genetic causes of sudden death is important because close relatives are also at potential risk of having a fatal cardiac condition. A comprehensive post-mortem investigation is vital to determine the cause and manner of death and provides the opportunity to assess the potential risk to the family after appropriate genetic counselling. In this paper, we present an update of the different genetic causes of sudden death, emphasizing their importance for the forensic pathologist due to his relevant role in the diagnosis and prevention of SCD.

A New Perspective in the Estimation of Postmortem Interval (PMI) Based on Vitreous [ K + ]

The relation between the potassium concentration in the vitreous humor, [K+], and the postmortem interval has been studied by several authors. Many formulae are available and they are based on a correlation test and linear regression using the PMI as the independent variable and [K+] as the dependent variable. The estimation of the confidence interval is based on this formulation. However, in forensic work, it is necessary to use [K+] as the independent variable to estimate the PMI. Although all authors have obtained the PMI by direct use of these formulae, it is, nevertheless, an inexact approach, which leads to false estimations. What is required is to change the variables, obtaining a new equation in which [K+] is considered as the independent variable and the PMI as the dependent. The regression line obtained from our data is [K+] = 5.35 + 0.22 PMI, by changing the variables we get PMI = 2.58[K+] - 9.30. When only nonhospital deaths are considered, the results are considerably improved. In this case, we get [K+] = 5.60 + 0.17 PMI and, consequently, PMI = 3.92[K+] - 19.04.

Characterization of Lesions in Hanging Deaths

Abstract:  Hanging is a common method of committing suicide and a routine task in medico‐legal autopsies. The hanging mark is the most relevant external sign and its characteristics are well known, but, for unknown reasons, there are major differences in reports on internal findings. We retrospectively studied 228 consecutive cases of hanging deaths. A complete standard autopsy was performed for every case. We investigated the association between the characteristics of the hanging mark and the frequency of bone, cartilage, soft tissue, and vascular injuries with the mode of suspension. Most cases (75.3%) presented some kind of bone or cartilage fracture, but these were unrelated to any of the variables studied. Vascular lesions are clearly more infrequent: intimal injuries were found in the carotid artery (9.1%), the jugular vein (2.2%), and ruptures of the carotid adventitial layer (21.7%). These could be partially associated with the use of a hard fixed noose and body weight.

Y chromosome STR haplotypes: genetic and sequencing data of the Galician population (NW Spain).

Abstract Recently described Y-STR polymorphisms can be analysed as informative haplotypes which are useful in the forensic field. In order to include these systems in our forensic routine, we have carried out a population study in Galicia (NW Spain) analysing seven Y-STR polymorphisms (DYS19, DYS389-I, DYS389-II, DYS390, DYS393 and DYS385: two loci). The results were compared with other population studies. In addition various alleles for each system (except DYS385) were sequenced and the corresponding allelic ladders constructed.

Improved estimation of postmortem interval based on differential behaviour of vitreous potassium and hypoxantine in death by hanging

Many formulae are available to estimate the relation between the potassium ([K+]) and hypoxantine ([Hx]) concentration in the vitreous humour and the postmortem interval (PMI). Typically these have been based on a correlation test and linear regression using the postmortal interval as the independent variable and [K+] or [Hx] as the dependent variable in order to estimate the confidence interval. However, a recent study has shown that a more precise measurement of PMI can be obtained if [K+] is used as the independent variable. The regression lines obtained from the most recent deceased subjects with forensic relevance received for autopsy in the Institute of Legal Medicine are [K+] = 5.589 + 0.174PMI and [Hx] = 26.459 + 3.017PMI, by changing the variables, we obtain PMI=3.967[K+] - 19.186 (R2 = 0.688, P < 0.001) and PMI = 0.172 [Hx] + 0.170 (R2 = 0.518, P < 0.001). In this paper we propose the cause of death as an extra factor which modifies the relationship and gives even greater precision in estimating PMI. In cases of death by hanging the results are considerably improved with [K+] = 5.224 + 0.225PMI and [Hx] = 15.161+4.957PMI, respectively, and consequently, PMI = 3.631[K+] - 17.334 (R2 = 0.818, P< 0.001) and PMI = 0.153[Hx] - 0.368 (R2 = 0.757, P < 0.001): the slope is less and the precision is obviously enhanced.

No Cash No Whiplash?: Influence of the Legal System on the Incidence of Whiplash Injury

Whiplash injury has been a continuous source of controversy due to its association with litigation. We studied the incidence of whiplash associated disorder (WAD) in two similar socioeconomic areas and carried out a retrospective study based on the hypothesis that the Spanish law 30/1995 might have an affect on the incidence and duration of cervical symptoms and the persistence of impairment. More than 10,000 patients injured in traffic accidents were studied over a period three years. Of these, only patients with an initial diagnosis of whiplash injury were included in the study. Patients with other injuries were excluded. The patients were classified into two groups: Galicia-Spain and North-Central Portugal (depending on where the accident took place and the medico-legal evaluation procedure in force). Statistical analysis was made using SPSS 13.0 and Statistix 8.0. We found a statistically significant difference between Spain and Portugal in the incidence of WAD and in the duration of symptoms. The incongruities caused by the compulsory application of Spanish law arise from the fact that evaluation on a points scale of impairment does not always reflect the functional state of the injured person.

Estimating adult stature from radiographically determined metatarsal length in a Spanish population

The ability to determine height in adult life can be crucial in the identification of skeletal remains. Very often, the small bones found among such remains are not only the most numerous, but also the best preserved, a fact which calls for more research into developing methods to estimate height from metatarsals. The aim of this paper is to verify the use of the dimensions of the metatarsals as estimators of adult height in a Spanish population using radiologically determined metatarsal lengths and to propose regression equations and test the formulae for determining adult stature. The present research is based on a study of 228 healthy Caucasoid adults from Galicia (NW Spain). The first and second metatarsals of the left foot were measured by a dorso-plantar X-ray using a digital medical image viewer. The best correlation obtained was with the maximum length of the 1st metatarsal for males. The corresponding regression equation is as follows: S=819.88+12.79 M1. A comparison of our statistical results with those of neighbouring population groups indicates that ours is more accurate. This must be due to the so-called specificity of regression equations in relation to the series on the base from which they were developed.

Applications of Tandem Mass Spectrometry (LC–MSMS) in estimating the post-mortem interval using the biochemistry of the vitreous humour

It is widely accepted that the quantification of potassium concentrations ([K+]) and hypoxanthine ([Hx]) in the vitreous humour is useful in estimating the time of death within a recent time interval. Despite all the advances made in this area, it is well recognized that difficulties in calibration, validation and the use of different methodologies and instrumentation from different laboratories may lead to obtaining different concentrations from the same sample. The extraction of the vitreous humour itself should also be carried out with a precise technique, taking care during the procedure to avoid causing any vascular injury that might lead to haematic contamination. Any fluid that is not clear could lead to erroneous results and should be discarded. We present a new LC-MSMS method developed for quantitative and qualitative analysis of [Hx] (valid also for guanine and xanthine), and qualitative determination of uric acid in vitreous humour. We also introduce a methodology to assess haematic contamination in order to improve the estimation of time since death. The method was fully validated in terms of linearity, sensitivity, imprecision, analytical recovery, extraction and process efficiency and matrix effect.

PMICALC: An R code-based software for estimating post-mortem interval (PMI) compatible with Windows, Mac and Linux operating systems

In legal medicine the correct determination of the time of death is of utmost importance. Recent advances in estimating post-mortem interval (PMI) have made use of vitreous humour chemistry in conjunction with Linear Regression, but the results are questionable. In this paper we present PMICALC, an R code-based freeware package which estimates PMI in cadavers of recent death by measuring the concentrations of potassium ([K+]), hypoxanthine ([Hx]) and urea ([U]) in the vitreous humor using two different regression models: Additive Models (AM) and Support Vector Machine (SVM), which offer more flexibility than the previously used Linear Regression. The results from both models are better than those published to date and can give numerical expression of PMI with confidence intervals and graphic support within 20 min. The program also takes into account the cause of death.

The use of computerized tomography in determining stature and sex from metatarsal bones

This study evaluates the efficacy of a radiological method to estimate stature from measurements of the first and second metatarsal taken from a collection of metatarsals of a Portuguese Caucasian population in which the measurements were made directly on the bone. The highest coefficient of determination and the lowest standard error were obtained with the physiological length of the second metatarsal (F2), using the equation S=895.4803+10.7848F2. The linear regressions obtained show significant differences between the estimated heights from M1. In addition, we offer a simple method for sex determination based on the maximum length (M1) and width (W1) of the first metatarsal, where W1=x1; (M1/W1)=x2; β0=55.4767; β1=-2.5796 and β2=-4.6898. Here we present a method of measurement using computerized tomography that enables population studies using live volunteers without incurring the difficulties of on the bone measurement.