Heavy metals in the volcanic environment and thyroid cancer.

In the last two decades thyroid cancer incidence has increased worldwide more than any other cancer. Overdiagnosis of subclinical microcarcinomas has certainly contributed to this increase but many evidences indicate that a true increase, possibly due to environmental factors, has also occurred. Thyroid cancer incidence is markedly increased in volcanic areas. Thus, the volcanic environment is a good model to investigate the possible factors favoring thyroid cancer. In the volcanic area of Mt. Etna in Sicily, as well as in other volcanic areas, a non-anthropogenic pollution with heavy metals has been documented, a consequence of gas, ash and lava emission. Soil, water and atmosphere contamination, via the food chain, biocontaminate the residents as documented by high levels in the urines and the scalp hair compared to individuals living in adjacent non-volcanic areas. Trace amounts of metals are essential nutrients but, at higher concentrations, can be toxic for living cells. Metals can behave both as endocrine disruptors, perturbing the hormonal system, and as carcinogens, promoting malignant transformation. Similarly to other carcinogens, the transforming effect of heavy metals is higher in developing organisms as the fetus (contaminated via the mother) and individuals in early childhood. In the last decades environment metal pollution has greatly increased in industrialized countries. Although still within the "normal" limits for each single metal the hormesis effect (heavy metal activity at very low concentration because of biphasic, non linear cell response) and the possible potentiation effect resulting from the mixture of different metals acting synergistically can explain cell damage at very low concentrations. The effect of metals on the human thyroid is poorly studied: for some heavy metals no data are available. The scarce studies that have been performed mainly focus on metal effect as thyroid endocrine disruptors. The metal concentration in tissues has been rarely measured in the thyroid. Heavy metal accumulation and metabolism in the thyroid or the carcinogenic activity of different doses and different speciation of metals has not been investigated. These studies are now warranted to better understand thyroid biology and heavy metal role in human thyroid carcinogenesis.

Neurotrophin-mimicking peptides at the biointerface with gold respond to copper ion stimuli.

The peptide fragments NGF1-14 and BDNF1-12, encompassing the N-terminal domains, respectively, of the proteins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were used in this study for the fabrication of a hybrid gold/peptide biointerface. These peptides mimic the Trk receptor activation of the respective whole protein - with a crucial role played by copper ions - and exhibit, in bulk solution, a pH-dependent capability to complex copper. We demonstrate here the maintenance of peptide-specific responses at different pH values as well as the copper binding also for the adlayers formed upon physisorption at the gold surface. The physicochemical properties, including viscoelastic behavior of the adlayer and competitive vs. synergic interactions in sequential adsorption processes, were addressed both experimentally, by quartz crystal microbalance with dissipation monitoring (QCM-D) and circular dichroism (CD), and theoretically, by molecular dynamics (MD) calculations. Proof-of work biological assays with the neuroblastoma SY-SH5H cell line demonstrated that the developed hybrid Au/peptide nanoplatforms are very promising for implementation in pH- and metal-responsive systems for application in nanomedicine.

Extracellular ATP induces cell death in human intestinal epithelial cells.

BACKGROUND: Extracellular ATP is an endogenous signaling molecule released by various cell types and under different stimuli. High concentrations of ATP released into the extracellular medium activate the P2X7 receptor in most inflammatory conditions. Here, we seek to characterize the effects of ATP in human intestinal epithelial cells and to evaluate morphological changes in these cells in the presence of ATP. METHODS: We treated human intestinal epithelial cells with ATP and evaluated the effects of this nucleotide by scanning and transmission electron microscopy analysis and calcium measurements. We used flow cytometry to evaluate apoptosis. We collected human intestinal explants for immunohistochemistry, apoptosis by the TUNEL approach and caspase-3 activity using flow cytometry analyses. We also evaluated the ROS production by flow cytometry and NO secretion by the Griess technique. RESULTS: ATP treatment induced changes characteristic of cell death by apoptosis and autophagy but not necrosis in the HCT8 cell line. ATP induced apoptosis in human intestinal explants that showed TUNEL-positive cells in the epithelium and in the lamina propria. The explants exhibited a significant increase of caspase-3 activity when the colonic epithelial cells were incubated with IFN-gamma followed by ATP as compared to control cells. In addition, it was found that antioxidants were able to inhibit both the ROS production and the apoptosis induced by ATP in epithelial cells. GENERAL SIGNIFICANCE: The activation of P2X7 receptors by ATP induces apoptosis and autophagy in human epithelial cells, possibly via ROS production, and this effect might have implications for gut inflammatory conditions.

Trypanosoma cruzi: activity of essential oils from Achillea millefolium L., Syzygium aromaticum L. and Ocimum basilicum L. on epimastigotes and trypomastigotes.

Trypanocidal activity of clove (Syzygium aromaticum L.), basil (Ocimum basilicum L.) and yarrow (Achillea millefolium L.) essential oils and some of their constituents (eugenol and linalool) was investigated on Trypanosoma cruzi epimastigote and bloodstream trypomastigote forms. Steam distillation was used to isolate the essential oils, with chemical analyses performed by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The IC(50) (concentration that inhibits 50% parasite growth) of the oils and constituents upon T. cruzi was determined by cell counting in a Neubauer chamber. Cell morphology alterations were observed by scanning and transmission electron microscopy. Treatment with oils and constituents demonstrated that they inhibit parasite growth, with clove essential being the most effective one (IC(50)=99.5 microg/ml for epimastigotes and 57.5 microg/ml for trypomastigotes). Ultrastructural alterations were observed mainly in the nucleus.

Effect of oregano (Origanum vulgare L.) and thyme (Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure.

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)(50) was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC(50)/24 h = 175 microg/ml) and also induced trypomastigote lysis (IC(50)/24 h = 115 microg/ml). Thyme essential oil presented IC(50)/24 h values of 77 microg/ml for epimastigotes and 38 mug/ml for trypomastigotes, while treatment with thymol resulted in an IC(50)/24 h of 62 microg/ml for epimastigotes and 53 microg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.

Lectin histochemistry of microglia in superior colliculus of the developing opossum

The development of microglia in the opossum superior colliculus (SC) has been studied by lectin histochemistry (Griffonia simplicifolia B4 isolectin, GsI/B4). Prior to the end of neurogenesis (by postconceptional day 26, PcD 26), there are virtually no GsI/B4+ cells in the SC parenchyma although rare roundish elements are found at the tectal and, in larger numbers, the tegmental border of the aqueduct. The appearance of microglia in the SC follows a ventrodorsal gradient, correlating with the direction of neurogenesis, cytomorphological differentiation and growth of the vascular network rather than with a leptomeningeal source, and without forecasting value for astroglial differentiation. In the superficial layers (sSC), relatively few but moderately ramified cells rather than macrophages coexist with regressive changes in retinocollicular axons (by PcD 39-53). By the end of and soon after this period, there is a striking increase in the number of fairly ramiried GsI/B4+ cells within the SC proper. Macrophages also become abundant but remain restricted to the vicinity of the aqueductal ependyma and are fewer at the tectal than at the tegmental aspect. These supraependymal macrophages as well as ramified parenchymal cells maintain the ability to divide at a low rate throughout maturation. The ingress via the aqueduct and cell proliferation may contribute to the complement of SC microglia but the major immediate source remains unknown.