Agostinho Santos

Iron levels in the human brain: a post-mortem study of anatomical region differences and age-related changes.

The link between brain iron homeostasis and neurodegenerative disease has been the subject of extensive research. There is increasing evidence of iron accumulation during ageing, and altered iron levels in some specific brain regions in neurodegenerative disease patients have been reported. Using graphite furnace atomic absorption spectrometry after microwave-assisted acid digestion of the samples, iron levels were determined in 14 different areas of the human brain [frontal cortex, superior and middle temporal, caudate nucleus, putamen, globus pallidus, cingulated gyrus, hippocampus, inferior parietal lobule, visual cortex of the occipital lobe, midbrain, pons (locus coeruleus), medulla and cerebellum (dentate nucleus)] of n=42 adult individuals (71±12 years old, range: 53-101 years old) with no known history or evidence of neurodegenerative, neurological or psychiatric disorders. It was found that the iron distribution in the adult human brain is quite heterogeneous. The highest levels were found in the putamen (mean±SD, range: 855±295μg/g, 304-1628μg/g) and globus pallidus (739±390μg/g, 225-1870μg/g), and the lowest levels were observed in the pons (98±43μg/g, 11-253μg/g) and medulla (56±25μg/g, 13-115μg/g). Globally, iron levels proved to be age-related. The positive correlation between iron levels and age was most significant in the basal ganglia (caudate nucleus, putamen and globus pallidus). Compared with the age-matched control group, altered iron levels were observed in specific brain areas of one Parkinsons disease patient (the basal ganglia) and two Alzheimers disease patients (the hippocampus).

Postmortem Analyses Unveil the Poor Efficacy of Decontamination, Anti-Inflammatory and Immunosuppressive Therapies in Paraquat Human Intoxications

Background Fatalities resulting from paraquat (PQ) self-poisonings represent a major burden of this herbicide. Specific therapeutic approaches have been followed to interrupt its toxic pathway, namely decontamination measures to prevent PQ absorption and to increase its excretion from organism, as well as the administration of anti-inflammatory and immunosuppressive drugs. Until now, none of the postmortem studies resulting from human PQ poisonings have assessed the relationship of these therapeutic measures with PQ toxicokinetics and related histopathological lesions, these being the aims of the present study. Methodology/Principal Findings For that purpose, during 2008, we collected human fluids and tissues from five forensic autopsies following fatal PQ poisonings. PQ levels were measured by gas chromatography-ion trap mass spectrometry. Structural inflammatory lesions were evaluated by histological and immunohistochemistry analysis. The samples of cardiac blood, urine, gastric and duodenal wall, liver, lung, kidney, heart and diaphragm, showed quantifiable levels of PQ even at 6 days post-intoxication. Structural analysis showed diffused necrotic areas, intense macrophage activation and leukocyte infiltration in all analyzed tissues. By immunohistochemistry it was possible to observe a strong nuclear factor kappa-B (NF-κB) activation and excessive collagen deposition. Conclusions/Significance Considering the observed PQ levels in all analyzed tissues and the expressive inflammatory reaction that ultimately leads to fibrosis, we conclude that the therapeutic protocol usually performed needs to be reviewed, in order to increase the efficacy of PQ elimination from the body as well as to diminish the inflammatory process.

Mechanical characterization and constitutive modelling of the damage process in rectus sheath

The aim of this study is to characterize and model the damage process in the anterior rectus abdominal aponeurosis (anterior rectus sheath) undergoing finite deformations. The resistance of the anterolateral abdominal aponeuroses is important when planning the surgical repair of incisional hernias, among other medical procedures. Previous experiments in prolapsed vaginal tissue revealed that a softening process occurs before tissue rupture. This nonlinear damage behaviour requires a continuum damage theory commonly used to describe the softening behaviour of soft tissues under large deformations. The structural model presented here was built within the framework of non-linear continuum mechanics. Tissue damage was simulated considering different damage behaviours for the matrix and the collagen fibres. The model parameters were fit to the experimental data obtained from anterior rectus sheath samples undergoing finite deformations in uniaxial tension tests. The tests were carried out with samples cut along the direction of the collagen fibres, and transversal to the fibres. Longitudinal and transverse mechanical properties of human anterior rectus sheath are significantly different. The damage model was able to predict the stress-strain behaviour and the damage process accurately. The error estimations pointed to an excellent agreement between experimental results and model fittings. For all the fitted data, the normalized RMS error ε presented very low values and the coefficient of determination R(2) was close to 1. The present work constitutes the first attempt (as far as the authors know) to present a damage model for the human rectus sheath.

Is the length of the sternum reliable for estimating adult stature? A pilot study using fresh sterna and a test of two methods using dry sterna.

Stature estimation is one of the four attributes of the biological profile obtained from human skeletal remains. The length of the long bones has been consistently used to estimate stature from regression equations, but these may be useless when dealing with fresh or decomposed mutilated remains. Until recently, there was no consistent assessment of the reliability of measurements of the sternum for stature estimation. The purpose of this paper is to test previously developed regression formulae for stature based on measurements of the dry sternum and to assess the reliability of measurements of the fresh sternum in estimating stature. The formulae developed by Menezes et al. and Singh et al. were applied to a sample of 5 known stature skeletons from the identified human skeletal collection curated at the National Museum of Natural History, in Lisbon, Portugal. Testing of these formulae showed that estimated stature confidence intervals do not allow discrimination between individuals with similar stature. The length of the fresh sternum was measured on a sample of 45 male individuals autopsied at the National Institute of Legal Medicine - North Delegation (Porto, Portugal). Cadaver length was regressed on sternum length and a simple linear regression formula was obtained. The regression model provided a 95% confidence interval of 13.32 cm and a correlation coefficient of only 0.329. Compared to other studies, regression formulae based on the length of the sternum provided considerably larger standard errors than that based on long bone lengths. These results suggest that the length of the sternum has limited forensic value and relatively low reliability in estimating stature from mutilated human skeletal remains, either skeletonized or fresh.

Sexual abuse of children. A comparative study of intra and extra-familial cases

The existing data suggest that individuals experiencing intra-familial abuse are affected more significantly than those experiencing extra-familial abuse. This study aims to identify possible differences between these types of abuse. A retrospective study was performed based on medico-legal reports related to children suspected of being sexually abused (n=1054). The results revealed that 40.2% of the suspected abuses were intra-familial and were significantly different than extra-familial cases with respect to the following: (a) the complainants were younger; (b) their relationship to the alleged abuser was closer; (c) the alleged abusers had higher rates of previous sexual abuse; (d) the suspected abuses were less intrusive physically; (e) there was less physical but more psychological violence; (f) the delay between the last abuse and the medico-legal examination was greater; and (g) there were fewer physical signs and DNA evidence (none in the great majority of cases). These results highlight aspects of intra-familial abuse that have been identified as factors influencing the severity of its consequences - physically, these instances of abuse were less intrusive but psychologically they were more intrusive than extra-familial abuse. This justifies the use of different strategies in the diagnosis and support for victims within the family.

Estimation of postmortem interval by hypoxanthine and potassium evaluation in vitreous humor with a sequential injection system.

The estimation of the time since death known as postmortem interval (PMI) is a main issue in the field of forensic science and legal medicine. In this work it is proposed a sequential injection system for the determination of hypoxanthine and potassium in the same sample of vitreous humor since the concentrations of both parameters change with PMI and the vitreous humor has been regarded as the ideal extracellular fluid for these kinds of determinations. By measuring both parameters the accuracy of estimation of PMI can be increased, and the effects of factors which influence the values in postmortem chemistry minimized. Hypoxanthine determination is based on its oxidation to uric acid (290 nm), catalyzed by immobilized xanthine oxidase, and the quantification of potassium levels in vitreous humor was performed using a tubular potassium ion-selective electrode. With a unique analytical cycle both analytes were evaluated being potassium levels determined during the degradation of hypoxanthine in the enzymatic reactor. Working concentration ranges between 6.04-40.00 micromol L(-1) and 7.00 x 10(-5) to 1.00 x 10(-1)mmol L(-1) were obtained, for hypoxanthine and potassium, respectively. The method proved to be reproducible with R.S.D. <5% for hypoxanthine and <3% for potassium. Sampling rate was approximately 30 per hour for the sequential determination of both parameters being 15 and 60 determinations per hour if hypoxanthine or potassium, where evaluated independently. Statistical evaluation at the 95% confidence level showed good agreement between the results obtained, for the vitreous humor samples, with both the SIA system and the comparison batch procedures. Moreover the methodology has low environmental impact in agreement with the demands of green analytical chemistry as only 2.7 mL of chemical waste is produced during both determinations.

Biomechanical Properties of Vaginal Tissue in Women with Pelvic Organ Prolapse

Background/Aims: To compare biomechanical properties of vaginal tissues between women with and without pelvic organ prolapse (POP) and investigate factors that may influence these properties. Methods: Forty patients submitted to POP surgery and 15 non-POP cadavers were evaluated. The tissue was excised from anterior and posterior middle third vagina. The biomechanical properties considered were stiffness (E) and maximum stress (Smax), and they were evaluated by means of uniaxial tension tests. Results: POP patients were associated with higher values of E (13.1 ± 0.8 vs. 9.5 ± 0.7 MPa; p < 0.001) and Smax (5.3 ± 0.5 vs. 3.2 ± 0.9 MPa; p < 0.001) in the anterior vaginal wall compared to the posterior wall. In contrast, non-POP women presented lower values of E (6.9 ± 1.1 vs. 10.5 ± 1.0 MPa; p = 0.01) and Smax (2.6 ± 0.4 vs. 3.5 ± 0.4 MPa; p = 0.043) in the anterior wall. The occurrence of POP was the only independent predictor of higher values of E and Smax in anterior vaginal samples (p = 0.003 and p = 0.008, respectively). Women with severe anterior vaginal prolapse presented higher levels of E and Smax in the anterior sample compared to those with lower POP stages (p = 0.001 and p = 0.01; respectively). Conclusion: Women with POP present significant changes of biomechanical properties in the vagina.

Firing Distance Estimation Through the Analysis of the Gunshot Residue Deposit Pattern Around the Bullet Entrance Hole by Inductively Coupled Plasma–mass Spectrometry: An Experimental Study

The use of inductively coupled plasma–mass spectrometry (ICP-MS) in the study of gunshot residues (GSR) is relatively recent, and only a few studies have been published on the subject. In the present paper, this instrumental technique has been used to study the deposit pattern of the GSR around the bullet entrance hole, through the analysis of antimony (Sb), barium (Ba), and lead (Pb). The data obtained were used to establish a mathematical model for estimating the firing distance. Test shots using a 6.35-mm pistol were made against a target of cotton tissue, and the amounts of Sb, Ba, and Pb deposited in quadrangular pieces of the target, cut from 4 radial positions, were determined by ICP-MS. In these experimental conditions, it was possible to estimate the firing distance on the interval [20–80] cm. The best linear correlation between ln m and d, where m is the mass of Sb, Ba, or Pb in the samples, expressed in μg/g of target tissue, and d the firing distance, was obtained at radial distances between 3.5 cm and 4.5 cm from the entrance hole. The best regression curve which adjusted to the data was a linear multiple regression between the firing distance and the logarithm of the mass of each element: d = a + b1X1 + b2X2 + b3X3, where X1 = ln m (Sb), X2 = ln m(Ba) and X3 = ln m (Pb). The accuracy of firing distance estimation using only 1 or 2 elements was not significantly different from the one obtained with the 3 elements.

Physical Inactivity is a Major Contributor to Ovariectomy-Induced Sarcopenia

Since the mechanism(s) underlying menopause-related sarcopenia remain unknown we aimed to investigate the role of physical inactivity in its etiology. Ovariectomized and sham-operated rats were allocated into 2 experimental groups: (1) sedentary-standard housing; and (2) exercise-housed with running wheel. After a 9-month experimental period, soleus muscle structure and biochemical properties were analyzed. No differences existed in muscle fibre size or ultrastructure between sedentary sham and ovariectomized animals housed in standard conditions. In the exercise groups, average daily running distance was 10-fold less in ovariectomized compared to sham-animals. Further, in exercised animals, soleus fibre size was smaller in ovariectomized compared to sham-animals. Nonetheless, compared to both sedentary groups, muscle fibre size was larger in the exercised ovariectomized animals. Our results indicate that ovariectomy-induced sarcopenia is not due to the loss of ovarian hormones per se, but is largely due to physical inactivity.

Mercury fatal intoxication: two case reports.

We report two cases of fatal intoxications with mercury, one intentional and the other allegedly resulting from a drug formulation mistake. Both cases occurred in the year of 2004. The first case refers to a man who ingested a great portion of a mercuric chloride solution. He attended a hospital emergency, submitted to treatment, but died after 49 days. In the second case, a woman applied on the chest skin an ointment containing a great quantity of mercury bromide. After 7 days of treatment in the hospital, she died. In both cases, samples of tissues and organs were collected at autopsy for mercury analysis. Because methylation of mercury in humans after exposure to metallic or inorganic mercury is almost unknown, both total mercury and methylmercury were quantified in the post-mortem samples. The quantifications were carried out by Cold Vapour Generation Atomic Absorption Spectrometry for total mercury and by HPLC-UV for methylmercury. The total mercury contents found in the post-mortem fluid and tissue samples were consentaneous with mercury poisoning. For the first case, the concentrations found, expressed in microg/g wet weight, were in the liver 49.9, lung 3.27 and brain 0.33, and for blood 11.7 microg/mL. For the second case, the concentrations expressed in microg/g wet weight were in the liver 46.6, lung 14.6, brain 0.21, kidney 77.7, stomach 7.12, spleen 6.4 and heart 2.34, and for blood and urine 2.95 and 1.40 microg/mL, respectively. Only in the first case was methylmercury found and quantified in liver (1.70 microg/g wet weight) and in blood (0.15 microg/mL) samples.