L. Concheiro

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.

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.

Prevalence of HCM and long QT syndrome mutations in young sudden cardiac death-related cases

Cardiomyopathies and channelopathies are major causes of sudden cardiac death. The genetic study of these diseases is difficult because of their heterogenic nature not only in their genetic traits but also in their phenotypic expression. The purpose of the present study is the analysis of a wide spectrum of previously known genetic mutations in key genes related to hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and Brugada syndrome (BrS) development. The samples studied include cases of sudden cardiac death (SCD) in young adults and their relatives in order to identify the real impact of genetic screening of SCD in forensic cases. Genetic screening of described variation in 16 genes implicated in the development of HCM and three more genes implicated in LQTS and BrS was performed by using MassARRAY™ technology. In addition, direct sequencing of the two most prevalent genes implicated in the development of SQTL type 1 and 2 was also carried out. Genetic screening allowed us to unmask four possibly pathogenic mutation carriers in the 49 SCD cases considered; carriers of mutation represent 9% (2/23) of the probands with structural anomalies found after autopsy and 7% (1/14) of the probands with structurally normal hearts after in depth autopsy protocol. One mutation was found among 12 of the recovered SCD cases considered. In people with direct family history of sudden cardiac death, but not themselves, 11 additional mutation carriers were found. Three different mutations were found in six of the 19 LQTS patients, representing three families and two different mutations were found among six patients with previous syncope. Genetic analysis in sudden cardiac death cases could help to elucidate the cause of death, but it also can help in the prevention of future deaths in families at risk. The study presented here shows the importance and relevance of genetic screening in patients with signs of cardiac hypertrophy and in family cases with more than one relative affected.

A silver staining method for the detection of polymorphic proteins in minute bloodstains after isoelectric focusing

A silver staining method has been developed to study polymorphic proteins in bloodstains after isoelectric focusing. This method is highly sensitive and permits the detection of polymorphic proteins (i.e. alpha 1-antitrypsin, Gc and Tf C subtypes) in bloodstains as small as 0.2 microliter or less. The method is simple and reproducible and can be used after immunofixation. Blood stains can be identified after longer storage periods than is possible by using conventional staining methods.

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.

A high-performance liquid chromatography method for hypoxanthine determination in vitreous humour : application to estimation of post mortem interval

We have developed a new technique to determine the concentration of hypoxanthine [Hx] in a reverse phase column using a modified high-performance liquid chromatography (HPLC) method that is faster and more reliable than those previously described. In this paper we present a formula for estimating the post mortem interval (PMI) based on this HPLC method by applying the inverse prediction method. The regression line obtained by changing the variables gives PMI=0.183[Hx]+0.599 (PMI in hours, [Hx] in μmol/L, R2-0.531, P-0.05).

Isoelectric Focusing Patterns of Some Mammalian Keratins

An isoelectric focusing method followed by silver staining has been used for the study of keratins from a total of 97 individuals belonging to 17 families and 39 species. The method distinguishes perfectly between two different animal species. In addition, there are often considerable differences between breeds and even occasionally slight individual differences which in no way impede the identification of a particular species as such.

Simultaneous Determination of Diazepam and its metabolites in Plasma by High-Performance Liquid Chromatography

Abstract A reversed phase high-performance liquid chromatographic method (HPLC) for the simultaneous determination of diazepam and its three active metabolites, nordazepam, oxazepam and temazepam, in plasma was proposed. The compounds were isolated by solid-phase extraction. The chromatographic mobile phase was metanol-water (55:45, v/v) at a flow rate of 1 mL/min. UV detection was performed concurrently at 240 and 254 nm.

The isoelectric focusing of keratins in hair followed by silver staining

An isoelectric focusing method followed by silver staining has been developed for the study of keratins which is as effective as two-dimensional electrophoresis and fluorography for hair species identification. Hair from dogs, rabbits, horses, cows, guinea-pigs, donkeys, sheep and cats were successfully identified. Narrow pH ranges were used to observe heterogeneity in human hair. Although this heterogeneity may be affected by environmental conditions, it may be of use in criminalistics.