Binding intensity and metal partitioning in soils affected by mining and smelting activities in Minas Gerais, Brazil.

Mining and smelting activities are potential sources of heavy metal contamination, which pose a threat to human health and ecological systems. This study investigated single and sequential extractions of Zn, Pb, and Cd in Brazilian soils affected by mining and smelting activities. Soils from a Zn mining area (soils A, B, C, D, E, and the control soil) and a tailing from a smelting area were collected in Minas Gerais state, Brazil. The samples were subjected to single (using Mehlich I solution) and sequential extractions. The risk assessment code (RAC), the redistribution index (U ts ), and the reduced partition index (I R ) have been applied to the sequential extraction data. Zinc and Cd, in soil samples from the mining area, were found mainly associated with carbonate forms. This same pattern did not occur for Pb. Moreover, the Fe-Mn oxides and residual fractions had important contributions for Zn and Pb in those soils. For the tailing, more than 70 % of Zn and Cd were released in the exchangeable fraction, showing a much higher mobility and availability of these metals at this site, which was also supported by results of RAC and I R . These differences in terms of mobility might be due to different chemical forms of the metals in the two sites, which are attributable to natural occurrence as well as ore processing.

Intratumoral heterogeneity of ADAM23 promotes tumor growth and metastasis through LGI4 and nitric oxide signals.

Intratumoral heterogeneity (ITH) represents an obstacle for cancer diagnosis and treatment, but little is known about its functional role in cancer progression. The A Desintegrin And Metalloproteinase 23 (ADAM23) gene is epigenetically silenced in different types of tumors, and silencing is often associated with advanced disease and metastasis. Here, we show that invasive breast tumors exhibit significant ADAM23-ITH and that this heterogeneity is critical for tumor growth and metastasis. We demonstrate that while loss of ADAM23 expression enhances invasion, it causes a severe proliferative deficiency and is not itself sufficient to trigger metastasis. Rather, we observed that, in ADAM23-heterotypic environments, ADAM23-negative cells promote tumor growth and metastasis by enhancing the proliferation and invasion of adjacent A23-positive cells through the production of LGI4 (Leucine-rich Glioma Inactivated 4) and nitric oxide (NO). Ablation of LGI4 and NO in A23-negative cells significantly attenuates A23-positive cell proliferation and invasion. Our work denotes a driving role of ADAM23-ITH during disease progression, shifting the malignant phenotype from the cellular to the tissue level. Our findings also provide insights for therapeutic intervention, enforcing the need to ascertain ITH to improve cancer diagnosis and therapy.

Increasing arsenic sorption on red mud by phosphogypsum addition.

Mining by-products have been tested as adsorbents for arsenic in order to reduce As bioavailability. This study evaluated a red mud (RM) treated with or without phosphogypsum (G) in order to improve its As retention. Red mud and G samples and their mixtures were chemically and mineralogically characterized to gather information concerning their composition, which is key for a better understanding of the adsorbent properties. Phosphogypsum was added to RM in the following proportions: 0, 1, 2, 5, 10, and 25% by weight. These mixtures were subjected to As adsorption and desorption and tested for their maximum adsorption capacity of As (AsMAC). Arsenic adsorption increased upon increasing the proportion of G added to RM. The AsMAC at pure RM reached 909 mg kg(-1), whereas the 75%-RM+25%-G mixture sorbed up to 3333 mg kg(-1) of As, i.e., a 3.5-fold increase in AsMAC. Using G in mixtures with RM increases the efficiency of As adsorption due to the presence of Ca(2+), which alters the charge balance of the adsorbent, leading to the formation of ternary complexes. Addition of G to RM is thus a promising technique to improve As retention, while providing additional value to both by-products, G and RM.

Auxiliary device for calibration of roller pumps: development and experimental results.

INTRODUCTION: Roller pumps are commonly used in surgeries involving extracorporeal circulation and its regulation may influence the hemolysis rate. OBJECTIVE: To describe an auxiliary device for adjusting roller pumps using the dynamic calibration method and show preliminary results of its application in surgical procedures. METHOD: The device was tested in the laboratory environment with three disposable pressure transducers normally used in surgeries. In the operation room, tests were carried out with two groups of patients. Free hemoglobin plasma rates were measured, 5 minutes after perfusion started and immediately before the passage of the residual volume of the pump. For Group 1 (n = 22), occlusion measurements were carried out using the drop rate method and for Group 2 (n = 18), measurements were carried out using the auxiliary device and 300 mmHg calibration (mean pressure for the dynamic calibration method). RESULTS: The auxiliary calibration device has shown calibration results statistically equal to those obtained with a reference device in the laboratory environment. We have found less variability of hemolysis rates in the operating room, using the auxiliary device and we did not observe any influence of unbalanced rollers in the hemolysis rates.

Genotoxic effects of aluminum, iron and manganese in human cells and experimental systems: a review of the literature.

There is considerable evidence indicating an increase in neurodegenerative disorders in industrialized countries. The clinical symptoms and the possible mutagenic effects produced by acute poisoning and by chronic exposure to metals are of major interest. This study is a review of the data found concerning the genotoxic potential of three metals: aluminum (Al), iron (Fe) and manganese (Mn), with emphasis on their action on human cells.

Accumulation of arsenic and nutrients by castor bean plants grown on an As-enriched nutrient solution.

Phytoextraction is a remediation technique that consists in using plants to remove contaminants from soils and water. This study evaluated arsenic (As) accumulation in Castor bean (Ricinus communis cv. Guarany) grown in nutrient solution in order to assess its phytoextraction ability. Castor bean plants were grown under greenhouse conditions in pots containing a nutrient solution amended with increasing doses of As (0, 10, 50, 100, 250, 500 and 5000 microg L(-1)) in a completely randomized design with four replications. Shoot and roots dry matter production as well as arsenic and nutrient tissue concentrations were measured at the end of the experiment. The results showed that increasing As concentration in nutrient solution caused a decrease in shoot and root biomass but did not result in severe toxicity symptoms in castor bean growing under a range of As concentration from 0 to 5000 microg L(-1). The As doses tested did not affect the accumulation of nutrients by castor bean. Although castor bean did not pose characteristics of a plant suitable for commercial phytoextraction, it could be useful for revegetation of As-contaminated areas while providing an additional income by oil production.

Multiscale representation for automatic identification of structures in medical images.

The identification of structures is a key step in several applications of medical imaging. In this work we propose a method for the identification of structures using a multiscale approach with inclusion of a priori information about the searched objects. After describing the image structures in the multiscale representation, a matching step determines which structure most likely corresponds to the target. Patterns are generated by previous application of the method to a set of images. We present a prototype for identifying structures in 2D images. A set of experiments was carried out to evaluate the prototype leading to encouraging results.

Genotoxic effects of rotenone on cultured lymphocytes

Rotenone is a heterocyclic compound widely used as an insecticide, acaricide and piscicide. Its toxicity is mainly caused by the inhibition of mitochondrial respiratory processes and ATP production, resulting in the generation of reactive oxygen species. Reactive oxygen species can interact with DNA, RNA and proteins, leading to cell damage, followed by death. We used the Comet assay, and we analyzed chromosome aberrations, in order to evaluate the genotoxic and clastogenic effects of rotenone on the different phases of the cell cycle. Cultured human lymphocytes were treated with 1.0, 1.5 and 2.0 microg/mL rotenone during the G1, G1/S, S (pulses of 1 and 6 h), and G2 phases of the cell cycle. Rotenone induced DNA damage and was clastogenic, but the clastogenicity was detected only with treatments conducted during the G1/S and S phases of the cell cycle. Rotenone also induced endoreduplication and polyploidy in treatments made during G1, while it significantly reduced the mitotic index in all phases of the cell cycle.

Redução de speckle em imagens médicas por ultra-som utilizando o método de diversidade de fase / Reduction of speckle in medical imaging by ultrasound using the method of phase diversity

Ultrasound B mode image is characterized by a deterministic artifact know as speckle. It comes from destructive coherent interference effects between overlapping echoes...

Loss and sprouting of nitric oxide synthase neurons in the human epileptic hippocampus.

PURPOSE: Nitric oxide (NO) has been implicated in a variety of functions, including the control of synaptic plasticity and sensory signaling. Current evidence suggests that this unconventional neurotransmitter mediates N-methyl-d-aspartate (NMDA) receptor-linked excitotoxicity. This study describes the expression of neuronal NO synthase (nNOS) immunoreactivity (IR) in hippocampi from patients with temporal lobe epilepsy (TLE). METHODS: Hippocampi from patients with clinical symptoms, neuroimaging, and EEG typical of hippocampal sclerosis (HS; n = 22) were compared with those from patients with neocortical temporal lesions (NONHS; n = 4) and autopsy (AUT; n = 18) patients for total cells, and nNOS-IR neuron and puncta densities. RESULTS: Compared with AUT, HS hippocampi had significantly less nNOS-IR neuron densities in the fascia dentata (FD); hilus, and CA4, CA3, CA2, and CA1 subfields. HS hippocampi had significantly greater nNOS-IR puncta densities in the FD, as compared with AUT and NONHS. CONCLUSIONS: Our results show that hippocampi from TLE patients exhibit a loss of nNOS-IR neurons and an abnormal FD innervation. The release of NO can influence the dynamics of ionic channels and neurotransmitter release, thus affecting neuronal membrane potential. Because the NOergic transmission does not obey the topographic constraints imposed on conventional transmitters, target cells can be stimulated even in regions with severe deafferentation. The plastic changes described here may contribute to abnormal hippocampal excitability.

Fetal alcohol exposure alters neurosteroid modulation of hippocampal N-methyl-D-aspartate receptors.

The actions of ethanol on brain ligand-gated ion channels have important roles in the pathophysiology of alcohol-related neurodevelopmental disorders and fetal alcohol syndrome. Studies have shown that N-methyl-d-aspartate (NMDA) receptors are among the ligand-gated ion channels affected by prenatal ethanol exposure. We exposed pregnant dams to an ethanol-containing liquid diet that results in blood ethanol levels near the legal intoxication limit in most states (0.08%). Primary cultures of hippocampal neurons were prepared from the neonatal offspring of these dams, and NMDA receptor function was assessed by patch clamp electrophysiological techniques after 6-7 days in culture in ethanol-free media. Unexpectedly, we did not detect any changes in hippocampal NMDA receptor function at either the whole-cell or single-channel levels. However, we determined that fetal alcohol exposure alters the actions of the neurosteroids pregnenolone sulfate and pregnenolone hemisuccinate, which potentiate NMDA receptor function. Western immunoblot analyses demonstrated that this alteration is not due to a change in the expression levels of NMDA receptor subunits. Importantly, in utero ethanol exposure did not affect the actions of neurosteroids that inhibit NMDA receptor function. Moreover, the actions of pregnenolone sulfate on type A gamma-aminobutyric acid and non-NMDA receptor function were unaltered by ethanol exposure in utero, which suggests that the alteration is specific to NMDA receptors. These findings are significant because they provide, at least in part, a plausible mechanistic explanation for the alterations in the behavioral responses to neurosteroids found in neonatal rats prenatally exposed to ethanol and to other forms of maternal stress (Zimmerberg, B., and McDonald, B. C. (1996) Pharmacol. Biochem. Behav. 55, 541-547).

A review of the effects of prenatal or early postnatal ethanol exposure on brain ligand-gated ion channels.

BACKGROUND: Ligand-gated ion channels mediate fast excitatory and inhibitory synaptic transmission in the developing central nervous system. These channels have been shown to have roles in neuronal proliferation, differentiation, and programmed cell death. Numerous studies over the past 10 years indicate that prenatal and/or early postnatal ethanol exposure affects neurotransmitter-gated ion channels. METHODS: We conducted a review of the relevant literature, identified by a computer-assisted literature search. This review presents an overview of studies performed with experimental preparations from the brains of rodents exposed to ethanol in utero and/or during the neonatal period and summarizes some of the salient issues that have developed in the course of these investigations. Differences in ethanol exposure paradigms and blood alcohol concentrations obtained in these studies are highlighted, and directions for future research are suggested. RESULTS: Most studies have focused on the effects of prenatal or early postnatal ethanol exposure on NMDA receptors. These studies show that ethanol exposure affects ligand binding, subunit expression, and function of this receptor. Fewer studies have examined ethanol's effects on ligand-gated ion channels other than NMDA receptors. For instance, a study reported changes in ligand binding to hippocampal kainate receptors. Another study found alterations in modulation of GABA(A) receptors by benzodiazepines and neurosteroids. CONCLUSIONS: These studies suggest that the effects of ethanol on brain ion channels may have a role in the pathophysiology of Alcohol-Related Neurodevelopmental Disorders and Fetal Alcohol Syndrome.

Ultrasonic pulsed Doppler blood flowmeter for use in extracorporeal circulation.

In cardiac surgeries, it is frequently necessary to make the external blood circulation and oxygenation artificially. This procedure is called extracorporeal circulation (EC) or heart-lung bypass. During EC, one of the most important parameters, which demands continuous monitoring, is the blood flow. In many cases, the blood flow is estimated by the pump velocity (in roller pumps) or measured with transducers based on electromagnetic methods (in centrifugal pumps). This article presents an ultrasonic Doppler blood flowmeter to be used in the arterial line of an extracorporeal circulation system. The ultrasonic probe is coupled to a half-inch tube connector of the extracorporeal arterial line, is not disposable, and does not need sterilization. The developed flowmeter revealed itself to be efficient and reliable and can be inserted in a closed-loop pump controller system or be used as stand-alone equipment.

Acute effects of ethanol on kainate receptors in cultured hippocampal neurons.

BACKGROUND: Kainate receptors are a subclass of ionotropic glutamate receptors that regulate excitability and mediate synaptic transmission and plasticity in the hippocampus. The acute effects of ethanol on these receptors are not completely understood. METHODS: The acute effects of ethanol on pharmacologically isolated kainate receptor-mediated currents were studied in cultured hippocampal neurons obtained from neonatal rats. Whole-cell patch-clamp electrophysiological techniques were used for these studies. LY303070 (GYKI-53784), a potent AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) receptor-selective noncompetitive antagonist, was used to isolate kainate currents. RESULTS: Kainate receptor-mediated currents corresponded to 7% of the total non-N-methyl-D-aspartate (non-NMDA) currents in these neurons and were reduced to 24% of control values in the presence of 15 microM lanthanum. These kainate receptor-mediated currents were significantly inhibited by ethanol concentrations of 50 mM or more. Under our recording conditions, ethanol inhibited non-NMDA receptor- and NMDA receptor-mediated currents to a similar extent as kainate receptor-mediated currents. Western blot analysis indicated that glutamate receptor-5 and -6/7 subunits, and kainic acid-2 subunits are expressed in these cultured hippocampal neurons. CONCLUSIONS: The present results suggest that kainate receptors are important targets for the actions of ethanol in the central nervous system.

Role of ERK/MAP kinase in mitogenic interaction between ACTH and FGF2 in mouse Y1 adrenocortical tumor cells.

In G0/G1 cell cycle-arrested Y1 adrenocortical cells FGF2 is a strong mitogen, whereas ACTH39 can be a weak mitogen or a strong anti-mitogenic agent. Phosphorylated ERK1/2-MAP kinases are undetectable by Western and immunocitochemistry assay in G0/G1-arrested Y1 adrenal cells. Cell entry into S phase linearly correlates with migration of phosphorylated ERK to nucleus. FGF2 rapid and strongly triggers transient phosphorylation of ERK1/2, whereas ACTH39 is a poor ERK1/2 activator. But, the MEK1 inhibitor, PD98059 (50microM), inhibits cFos and cyclin D1 induction and DNA synthesis stimulation by both ACTH39 and FGF2, suggesting that ERK1/2 activation mediates the strong and the weak mitogenic effect of, respectively, FGF2 and ACTH39. In addition, ACTH39 antagonizes the FGF2 mitogenic effect keeping untouched ERK1/2 activation, c-Fos and cyclin D1 induction.

Histochemical characterization of NADPH-diaphorase activity in area 17 of diurnal and nocturnal primates and rodents.

NADPH-diaphorase (NADPH-d) activity was studied comparatively in area 17 of four mammalian species, two primates and two rodents. Three brain hemispheres each from adult capuchin-monkeys, owl-monkeys, agoutis and guinea pigs were fixed with aldehyde fixatives by perfusion and 200 microns sections were submitted to NADPH-d histochemistry, using the indirect malic enzyme method. In all species studied the neuropil pattern of enzymes activity presented a clear layered appearance. In primates, histochemical staining was most intense in layer IVc, while in rodents the highest intensity of the neuropil reaction was in supragranular layers (II and III). Comparison of cell density in grey and white matter showed that the majority of NADPH-d-positive neurones were located in the white matter of primates but not of rodents. Since NADPH-d is a nitric oxide synthase the results are very important for comparative functional studies of neuromediators and their correlations with laminar and modular organization of area 17 of the mammalian brain.

Histochemical characterization of NADPH-diaphorase activity in area 17 of diurnal and nocturnal primates and rodents

NADPH-diaphorase (NADPH-d) activity was studied comparatively in area 17 of four mammalian species, two primates and two rodents. Three brain hemispheres each from adult capuchin-monkeys, owl-monkeys, agoutis and guinea pigs were fixed with aldehyde fixatives by perfusion and 200 mum sections were submitted to NADPH-d histochemistry, using the indirect malic enzyme method. In all species studied the neuropil pattern of enzyme activity presented a clear layered appearance. In primates, histochemical staining was most intense in layer IVc, while in rodents the highest intensity of the neuropil reaction was in supragranular layers (II and III). Comparison of cell density in grey and white matter showed that the majority of NADPH-d-positive neurones were located in the white matter of primates but not of rodents. Since NADPH-d is a nitric oxide synthase the results are very important for comparative functional studies of neuromediators and their correlations with laminar and modular organization of area 17 of the mammalian brain.

A portable microprocessor-based triggering device for cardiac muscle electrical stimulation.

We describe a microprocessor-based programmable triggering instrument designed to control the distribution in time of electrical stimuli delivered to a heart muscle preparation. Sequences of stimuli may be selected among those stored in the non-volatile memory of the instrument and new sequences may be programmed using a repertory of 25 commands. The instrument was used to study the inotropic effects of three irregular sequences of stimuli applied to the isolated rat left atrium. The mean peak tension developed by the tissue was unaltered by stimulus sequence, provided the mean stimulatory frequency (2 or 5 Hz) was maintained. The instrument may be useful to study the effect of different stimulatory patterns on cardiac inotropism, as well as for controlling the electrical stimulation of other biological preparations.

A portable microprocessor-based triggering device for cardiac muscle electrical stimulation

We describe a microprocessor-based programmable triggering instrument designed to control the distribution in time of electrical stimuli delivered to a heart muscle preparation. Sequences of stimuli may be selected among those stored in the non-volatile memory of the instrument and new sequences may be programmed using a repertory of 25 commands. The instrument was used to study the inotropic effects of three irregular sequences of stimuli applied to the isolated rat left atrium. The mean peak tension developed by the tissue was unaltered by stimulus sequences, provided the mean stimulatory frequency (2 or 5 Hz) was maintained. The instrument may be useful to study the effect of different stimulatory patterns on cardiac inotropism, as well as for controlling the electrical simulation of tother biological preparation

Reflections on tissue characterisation.

Theoretical predictions that absorption and velocity dispersion, in addition to characteristic acoustic impedance mismatch, mediate the reflectivity of a planar interface are explored. A technique to measure the frequency dependence of the reflectivity is described: a special hydrophone, purpose-built to this end, is utilised in order to show that perspex/water and neoprene/water reflectivities are not inconsistent with the general predictions of the theory. An approach towards displaying, simultaneously, both the temporal and spectral properties of ultrasound pulses is described, and its potential utility in both reflectivity measurement and investigation of non-linear propagation is proposed.