Fernando Garcia e Costa

Heavy Metals and Human Health

Metals occur naturally in the earths crust, and their contents in the environment can vary between different regions resulting in spatial variations of background concentrations. The distribution of metals in the environment is governed by the properties of the metal and influences of environmental factors (Khlifi & Hamza-Chaffai, 2010). Of the 92 naturally occurring elements, approximately 30 metals and metalloids are potentially toxic to humans, Be, B, Li, Al, Ti, V, Cr, Mn, Co, Ni, Cu, As, Se, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Cs, Ba, W, Pt, Au, Hg, Pb, and Bi. Heavy metals is the generic term for metallic elements having an atomic weight higher than 40.04 (the atomic mass of Ca) (Ming-Ho, 2005). Heavy metals enter the environment by natural and anthropogenic means. Such sources include: natural weathering of the earth’s crust, mining, soil erosion, industrial discharge, urban runoff, sewage effluents, pest or disease control agents applied to plants, air pollution fallout, and a number of others (Ming-Ho, 2005). Although some individuals are primarily exposed to these contaminants in the workplace, for most people the main route of exposure to these toxic elements is through the diet (food and water). The contamination chain of heavy metals almost always follows a cyclic order: industry, atmosphere, soil, water, foods and human. Although toxicity and the resulting threat to human health of any contaminant are, of course, a function of concentration, it is well-known that chronic exposure to heavy metals and metalloids at relatively low levels can cause adverse effects (Agency for Toxic Substance and Disease Registry [ATSDR], 2003a, 2003b, 2007, 2008; Castro-Gonzalez & Mendez-Armenta, 2008). Therefore, there has been increasing concern, mainly in the developed world, about exposures, intakes and absorption of heavy metals by humans. Populations are increasingly demanding a cleaner environment in general, and reductions in the amounts of contaminants reaching people as a result of increasing human activities. A practical implication of this trend, in the developed countries, has been the imposition of new and more restrictive regulations (European Commission, 2006; Figueroa, 2008).

Spermatogenesis recovery in the mouse after iron injury.

Alloys used as prosthetic devices for bone/joint replacement include some heavy metals such as chromium, iron, nickel, or titanium. Unfortunately, due to the aggressive nature of the physiological environment, corrosion of these alloys promotes the release of metal ions into the surrounding tissues causing systemic toxic effects. Our previous preliminary studies have demonstrated that iron induced several morphological changes within mice seminiferous epithelium. The aim of the present work was to investigate, over a one-month period, the possibility of recovery of mice seminiferous epithelium, previously damaged by iron. Male Charles River mice were dosed subcutaneously with 0.5 mL of an iron suspension of 538 mg/L9-10 10 mg/L (n-5) every 72 hours during two weeks, followed by a recovery period of 30 days. Fragments of the seminiferous tubules were fixed in glutaraldehyde and prepared for light and transmission electron microscopy. Regeneration of spermatogenesis was noted after a one-month period, as illustrated by the presence of normal germ cells, in the usual position within the seminiferous tubules. These germinal elements and the Sertoli cells have shown normal cytological features. These results strongly suggest that the deleterious effects induced by iron are reversible. The presence of residual bodies within Sertoli cells cytoplasm indicates that they are able to perform a normal functional activity in a recovered spermatogenesis.

VMR: volunteer MapReduce over the large scale internet

Volunteer Computing systems (VC) harness computing resources of machines from around the world to perform distributed independent tasks. Existing infrastructures follow a master/worker model, with a centralized architecture, which limits the scalability of the solution given its dependence on the server. We intend to create a distributed model, in order to improve performance and reduce the burden on the server. In this paper we present VMR, a VC system able to run MapReduce applications on top of volunteer resources, over the large scale Internet. We describe VMRs architecture and evaluate its performance by executing several MapReduce applications on a wide area testbed. Our results show that VMR successfully runs MapReduce tasks over the Internet. When compared to an unmodified VC system, VMR obtains a performance increase of over 60% in application turnaround time, while reducing the bandwidth use by an order of magnitude.

BOINC-MR: MapReduce in a Volunteer Environment

Volunteer Computing (VC) harnesses computing resources from idle machines around the world to execute independent tasks, following a centralized master/worker model.

Histomorphological evaluation of mice testis after co-exposure to lead and cadmium

Abstract Objective The present study investigates the effects of co-exposure to lead and cadmium on mice testis using histomorphological approach. Methods Male mice were subcutaneously injected with lead chloride on day 1 and cadmium chloride on day 2 (74 and 1 mg/kg body weight, respectively), and kept for 24 h. Vehicle control group was also considered. Mice were then sacrificed and testis were collected and weighed. Samples were fixed on Bouins solution and processed for histology. The diameter of seminiferous tubules in both groups was calculated using software based on deformable models (SNAKE). Results The combined exposure of lead and cadmium induced degenerative changes in testis, namely, wavy contour of seminiferous tulules, germ cell loss, and release of immature cells into the lumen. Atrophy of seminiferous tubules was seen in this group, confirmed by a significant ( P Conclusions Cumulative effects of lead and cadmium may have disrupted the blood-testis barrier, then causing the histopathological lesions within testis.

The Role of Cytometry for Male Fertility Assessment in Toxicology

Infertility is nowadays a major concern, affecting approximately 8–12% of the couples and the male factor accounts for about 50% of the cases. Occupational and/or environ‐ mental exposure to heavy metals and other pollutants is the main cause of male infertility. Lead, cadmium and chromium are heavy metals widely used in industry and quite persistent in the environment, raising major concerns over the possible effects on the reproductive health of workers and the general population. Sperm DNA integrity is essential for the accurate transmission of paternal genetic information, and normal sperm chromatin structure is important for sperm fertilizing ability. Flow cytometry can be to characterize multiple physical characteristics of the population of spermato‐ zoa in the sperm, including sperm concentration, viability, mitochondrial mass and function, acrosome integrity, capacitation, membrane fluidity, DNA content and status, etc. This chapter elucidates the role of cytometry in the study of male fertility under toxicological insult by pollutants such as chromium, cadmium and lead. Some representative examples are presented using in vivo studies with rodents. In addition, complementary techniques to cytometry and future perspectives will be mentioned in an interdisciplinary point of view to gain knowledge on this subject.

Biological Responses of in vivo Studies to Contaminants: A Contribution to Improve Public Health Knowledge

Global climate changes and ecosystems deterioration due to several human activities in‐ volving environmental hazards have a great impact on human welfare [1]. These factors added to many other stressors are responsible for emerging diseases worldwide, which represent an important endeavour. For this reason the risk of contaminants on human health is an expanding area of environmental epidemiology. This sub-field of epidemiol‐ ogy addresses, not only the environmental factors affecting the health and illness of pop‐ ulations but also offers public education on environmental issues. Matters such as sources of environmental contaminants, assessment of how exposure to a hazardous chemical may occur, measurement of health effects, and applying appropriate controls are relevant issues of this branh [2]. Surveillance platforms for hazardous environmental factors involving data collection and analyses, and public health promotion through evi‐ dence-based approaches are also within the scope of this growing field. Nowadays, at‐ tention to chemical and physical factors have gained special care within the scope of environmental epidemiology due to the myriad of pollutants persisting in water bodies, air, crop lands, and other environmental settings.