Soil Carbon Turnover Measurement by Physical Fractionation at a Forest-to-Pasture Chronosequence in the Brazilian Amazon

The effect of conversion from forest-to-pasture upon soil carbon stocks has been intensively discussed, but few studies focus on how this land-use change affects carbon (C) distribution across soil fractions in the Amazon basin. We investigated this in the 20 cm depth along a chronosequence of sites from native forest to three successively older pastures. We performed a physicochemical fractionation of bulk soil samples to better understand the mechanisms by which soil C is stabilized and evaluate the contribution of each C fraction to total soil C. Additionally, we used a two-pool model to estimate the mean residence time (MRT) for the slow and active pool C in each fraction. Soil C increased with conversion from forest-to-pasture in the particulate organic matter (> 250 mu m), microaggregate (53-250 mu m), and d-clay (< 2 mu m) fractions. The microaggregate comprised the highest soil C content after the conversion from forest-to-pasture. The C content of the d-silt fraction decreased with time since conversion to pasture. Forest-derived C remained in all fractions with the highest concentration in the finest fractions, with the largest proportion of forest-derived soil C associated with clay minerals. Results from this work indicate that microaggregate formation is sensitive to changes in management and might serve as an indicator for management-induced soil carbon changes, and the soil C changes in the fractions are dependent on soil texture.

Crystallisation behaviours of Al-based metallic glasses: Compositional and topological aspects

The different types of thermal crystallisation behaviours observed during continuous heating of M-based metallic glasses have been successfully associated with the topological instability. criterion, which is simply calculated from the alloy composition and metallic radii of the alloying elements and aluminium. In the present work, we report on new results evidencing the correlation between the values of X and the crystallisation behaviours in Al-based alloys of the Al-Ni-Ce system and we compare the glass-forming abilities of alloys designed with compositions corresponding to the same topological instability condition. The results are discussed in terms of compositional and topological aspects emphasizing the relevance of the different types of clusters in the amorphous phase in defining the stability of the glass and the types of thermal crystallisation. (C) 2008 Elsevier B.V. All rights reserved.

Route to chaos in a third-order phase-locked loop network

Phase-locked loops (PLLs) are widely used in applications related to control systems and telecommunication networks. Here we show that a single-chain master-slave network of third-order PLLs can exhibit stationary, periodic and chaotic behaviors, when the value of a single parameter is varied. Hopf, period-doubling and saddle-saddle bifurcations are found. Chaos appears in dissipative and non-dissipative conditions. Thus, chaotic behaviors with distinct dynamical features can be generated. A way of encoding binary messages using such a chaos-based communication system is suggested. (C) 2009 Elsevier B.V. All rights reserved.

Elevated blood lead levels in a riverside population in the Brazilian Amazon

Lead (Pb) is recognized as one of the most toxic metals. Sources of Pb exposure have been widely documented in North America, and the removal of Pb additives from gasoline was reflected in a dramatic lowering of blood Pb concentration. In Latin America, the removal of Pb from gasoline resulted in decreased exposure, but Pb levels in many areas remain high due to occupational and environmental sources of exposure. While many of the Pb sources have been identified (mining, industries, battery recycling, lead-based paint, ceramics), new ones occasionally crop up. Here we report on blood Pb (B-Pb) levels in remote riverside communities of the Brazilian Amazon. Blood Pb (B-Pb) levels were determined in 448 persons from 12 villages of the Lower Tapajos River Basin, Par, Brazil. Socio-demographic and dietary information, as well as occupational, residential and medical history was collected using an interview-administered questionnaire. B-Pb, measured by ICP-MS, showed elevated concentrations. Mean B-Pb was 13.1 mu g/dL +/- 8.5, median B-Pb was 11.2 mu g/dL and ranged from 0.59 to 48.3 mu g/dL. Men had higher B-Pb compared to women (median: 15.3 mu g/dL vs 7.9 mu g/dL respectively). B-Pb increased with age for women, while it decreased for men. For both genders, B-Pb decreased with education. There were significant differences between villages. Exploratory analyses, using linear partition models, showed that for men B-Pb was lower among those who were involved in cattle-raising, and higher among those who hunted, farmed and fished. The distribution profile of B-Pb directed us towards artisanal transformation of manioc to flour (farinha), which requires heating in a large metal pan, with stirring primarily done by young men. In the village with the highest B-Pb, analysis of Pb concentrations (dry weight) of manioc (prior to transformation) and farinha (following transformation) from 6 houses showed a tenfold increase in Pb concentration (mean: 0.017 +/- 0.016 to 0.19 +/- 0.10 mu g/g). This was confirmed in one of these villages where we sampled manioc paste Oust before roasting) and the roasted farinha (0.05 mu g/g vs 0.20 mu g/g). While there may be other sources (ammunition, sinkers for fishing nets), the high concentrations in farinha, a dietary staple, assuredly makes an important contribution. Further action needs to reduce Pb sources in this region. (C) 2009 Elsevier Inc. All rights reserved.

Modeling volatile organic compounds (voc`s) adsorption onto cup-stacked carbon nanotubes (cscnt) using the linear driving force model

Modeling volatile organic compounds (voc`s) adsorption onto cup-stacked carbon nanotubes (cscnt) using the linear driving force model. Volatile organic compounds (VOC`s) are an important category of air pollutants and adsorption has been employed in the treatment (or simply concentration) of these compounds. The current study used an ordinary analytical methodology to evaluate the properties of a cup-stacked nanotube (CSCNT), a stacking morphology of truncated conical graphene, with large amounts of open edges on the outer surface and empty central channels. This work used a Carbotrap bearing a cup-stacked structure (composite); for comparison, Carbotrap was used as reference (without the nanotube). The retention and saturation capacities of both adsorbents to each concentration used (1, 5, 20 and 35 ppm of toluene and phenol) were evaluated. The composite performance was greater than Carbotrap; the saturation capacities for the composite was 67% higher than Carbotrap (average values). The Langmuir isotherm model was used to fit equilibrium data for both adsorbents, and a linear driving force model (LDF) was used to quantify intraparticle adsorption kinetics. LDF was suitable to describe the curves.

Early Increase in Myocardial Perfusion After Stem Cell Therapy in Patients Undergoing Incomplete Coronary Artery Bypass Surgery

Incomplete revascularization is associated with worse long-term outcomes. Autologous bone marrow cells (BMC) have recently been tested in patients with severe coronary artery disease. We tested the hypothesis that intramyocardial injection of autologous BMC increases myocardial perfusion in patients undergoing incomplete coronary artery bypass grafting (CABG). Twenty-one patients (19 men), 59 +/- 7 years old, with limiting angina and multivessel coronary artery disease (CAD), not amenable to complete CABG were enrolled. BMC were obtained prior to surgery, and the lymphomonocytic fraction separated by density gradient centrifugation. During surgery, 5 mL containing 2.1 +/- 1.3 x 10(8) BMC (CD34+ = 0.8 +/- 0.3%) were injected in the ischemic non-revascularized myocardium. Myocardial perfusion was assessed by magnetic resonance imaging (MRI) at baseline and 1 month after surgery. The increase in myocardial perfusion was compared between patients with < 50% (group A, n = 11) with that of patients with > 50% (group B, n = 10) of target vessels (stenosis a parts per thousand yenaEuro parts per thousand 70%) successfully bypassed. Injected myocardial segments included the inferior (n = 12), anterior (n = 7), and lateral (n = 2) walls. The number of treated vessels (2.3 +/- 0.8) was significantly smaller than the number of target vessels (4.2 +/- 1.0; P < 0.0001). One month after surgery, cardiac MRI showed a similar reduction (%) in the ischemic score of patients in group A (72.5 +/- 3.2), compared to patients in group B (78.1 +/- 3.2; P = .80). Intramyocardial injection of autologous BMC may help increase myocardial perfusion in patients undergoing incomplete CABG, even in those with fewer target vessels successfully treated. This strategy may be an adjunctive therapy for patients suffering from a more advanced (diffuse) CAD not amenable for complete direct revascularization.

Propranolol reduces variceal pressure and wall tension in schistosomiasis presinusoidal portal hypertension

Background and Aim: Although prophylaxis with beta-blockers has been shown to decrease variceal pressure and wall tension in cirrhotic patients, this has not been demonstrated in non-cirrhotic portal hypertension caused by Schistosoma mansoni infection. Methods: Thirteen patients without history of previous gastrointestinal bleeding were included. All of them had high-risk esophageal varices at endoscopy. An endoscopic gauge and a high-frequency endoscopic ultrasonography miniprobe were used to assess transmural variceal pressure and wall tension before and after achieving beta-blockade with propranolol. Results: Baseline variceal pressure decreased from 13.3 +/- 3.5 to 8.2 +/- 2.0 mmHg (P < 0.0001) and wall tension from 500.2 +/- 279.8 to 274.0 +/- 108.3 mg.mm-1. The overall effect of propranolol on decreasing variceal pressure and wall tension expressed in percentage change in relation to baseline values was 35.7 +/- 18.4% and 35.9 +/- 26.7%, respectively (P = 0.9993). Conclusion: Propranolol significantly reduced variceal pressure and wall tension in schistosomiasis.

Frequency of concurrent autoimmune disorders in patients with autoimmune hepatitis - Effect of age, gender, and genetic background

Background: Concurrent autoimmune disorders (CAIDs) have been shown to occur in 22% to 34% of the patients with autoimmune hepatitis (AIH). Their presence has been linked to female gender, older age, and to certain HLA antigens, namely HLA-A11. DRB1*04, and DRB4*01. Aims: To assess the frequency and nature of CAID in Brazilian patients with AIH types 1 (AIH-1) and 2 (AIH-2) and to investigate the influence of age, gender, and genetic background in their occurrence. Patients and Methods: The presence and nature of CAID was studied in 143 patients [117 females, median age 11 (1.3 to 69)] with AIH-1 (n = 125) and AIH-2 (n = 28). HLA typing and tumor necrosis factor a gene promoter and exon I cytotoxic T lymphocyte associated antigen 4 (CTLA-4) gene polymorphisms were determined by polymerase chain reaction-based techniques. Results: The frequency of CAID was similar in patients with AIH-1 (14%) and AIH-2 (18%), but their nature was shown to vary. Arthritis was seen in half of the patients (n = 8) with CAID and AIH-1 and in none of those with AIH-2. Subjects with AIH-1 and CAID were shown to be older [24 (1.3 to 6 1) vs. 11 (1.3 to 69) y P = 0.02] and to have more often circulating antinuclear antibody (76% vs. 40%, P = 0.008) and less frequently antiactin antibodies (33% vs. 75%, P = 0.008) when compared with their counterparts without CAID. No particular HLA-DR and DQ alleles, as well as tumor necrosis factor a and CTLA-4 genotypes, were associated with CAID. Conclusions: The nature, but not the frequency, of CAID was shown to vary in AIH-1 and AIH-2. In subjects with AIH-1, CAID was linked to older subjects and to the presence of antinuclear antibody. No predisposition to CAID was associated to HLA-DRB1*04 or DDB4*01 alleles. The observed lower frequency of CAID could be attributed to the lower age of disease onset in Brazilians and to differences in HLA-encoded susceptibility to AIH-1 observed in South America.

The influence of Flutter (R) VRP1 components on mucus transport of patients with bronchiectasis

Background: The Flutter (R) VRP1 combines high frequency oscillation and positive expiratory pressure (PEP). Objective: To separately evaluate the effect of the Flutter (R) VRP1 components (high frequency oscillation and PEP) on mucus transportability in patients with bronchiectasis. Methods: Eighteen patients with bronchiectasis received sessions with the Flutter (R) VRP1 or PEP for 30 min daily in a randomized, crossover study. The treatment duration was four weeks with one of the therapies, one week of a ""wash-out"" period and followed by four more weeks with the other treatment. Weekly secretion samples were collected and evaluated for mucociliary relative transport velocity (RTV), displacement in a simulated cough machine (SCM) and contact angle measurement (CAM). For the proposed comparisons, a linear regression model was used with mixed effects with a significance level of 5%. Results: The Flutter (R) VRP1 treatment resulted in greater displacement in SCM and lower CAM when comparing results from the first (9.6 +/- 3.4 cm and 29.4 +/- 5.7 degrees, respectively) and fourth weeks of treatment (12.44 +/- 10.5 cm and 23.28 +/- 6.2, respectively; p < 0.05). There was no significant difference in the RTV between the treatment weeks for either the Flutter (R) VRP1 or PEP. Conclusion: The use of the Flutter (R) VRP1 for four weeks is capable of altering the respiratory secretion transport properties, and this alteration is related to the high frequency oscillation component. (C) 2011 Elsevier Ltd. All rights reserved.

Activation of cannabinoid CB, receptors in the dorsolateral periaqueductal gray induces anxiolytic effects in rats submitted to the Vogel conflict test

There are contradictory results concerning the effects of systemic injections of cannabinoid agonists in anxiety-induced behavioral changes. Direct drug administration into brain structures related to defensive responses could help to clarify the role of cannabinoids in these changes. Activation of cannabinoid CB, receptors in the dorsolateral periaqueductal gray induces anxiolytic-like effects in the elevated plus maze. The aim of this work was to verify if facilitation of endocannabinoid-mediated neurotransmission in this region would also produce anxiolytic-like effects in another model of anxiety, the Vogel conflict test. Male Wistar rats (n = 5-9/group) with cannulae aimed at the dorsolateral periaqueductal gray were water deprived for 24 h and pre-exposed to the apparatus where they were allowed to drink for 3 min. After another 24 h-period of water deprivation, they received the microinjections and, 10 min later, were placed into the experimental box. in this box an electrical shock (0.5 nnA, 2 s) was delivered in the spout of a drinking bottle at every twenty licks. The animals received a first microinjection of vehicle (0.2 mu l) or AM251 (a cannabinoid CB1 receptor antagonist; 100 pmol) followed, 5 min later, by a second microinjection of vehicle, anandamide (an endocannabinoid, 5 pmol), AM404 (an inhibitor of anandamide uptake, 50 pmol) or URB597 (an inhibitor of Fatty Acid Amide Hydrolase, 0.01 or 0.1 nmol). Anandamide, AM404 and URB597 (0.01 nmol) increased the total number of punished licks. These effects were prevented by AM251. The results give further support to the proposal that facilitation of CB1 receptor-mediated endocannabinoid neurotransmission in the dorsolateral periaqueductal gray modulates defensive responses. (C) 2008 Elsevier B.V. All rights reserved.

Activation of CB1 cannabinoid receptors in the dorsolateral periaqueductal gray reduces the expression of contextual fear conditioning in rats

Rationale Conditioned fear to context causes freezing and cardiovascular changes in rodents and has been used to measure anxiety. It also activates the dorsolateral column of the periaqueductal gray (dlPAG). Microinjections of cannabinoid agonists into the dlPAG produced anxiolytic-like effects in the elevated plus maze, but the effects of these treatments on fear conditioning remains unknown. Objective The objective of this study was to verify if intra-dlPAG injection of the CB1 cannabinoid receptor agonist anandamide (AEA) or the anandamide transport inhibitor AM404 would attenuate behavioral (freezing) and cardiovascular (increase of arterial pressure and heart rate) responses of rats submitted to a contextual fear-conditioning paradigm. Materials and methods Male Wistar rats with cannulae aimed at the dlPAG were re-exposed to a chamber where they had received footshocks 48 h before. Fifteen minutes before the test, the animals received a first intra-dlPAG injection of vehicle or AM251, a CB1 receptor antagonist (100 pmol/200 nl), followed 5 min later by vehicle, AEA (5 pmol/200 nl) or AM404 (50 pmol/200 nl). Freezing and cardiovascular responses were recorded for 10 min. Results Freezing and cardiovascular responses were reduced by administration of either AEA or AM404 into the dlPAG before re-exposition to the aversively conditioned context. These effects were abolished when the animals were locally pretreated with AM251. The latter drug, even at a higher dose (300 pmol), was ineffective when administered alone into the dlPAG. Conclusion The results suggest that facilitation of endocannabinoid-mediated neurotransmission in the dlPAG, through activation of local CB1 receptors, attenuates the expression of contextual fear responses.

DIFFERENT ROLE OF THE VENTRAL MEDIAL PREFRONTAL CORTEX ON MODULATION OF INNATE AND ASSOCIATIVE LEARNED FEAR

Reversible inactivation of the ventral portion of medial prefrontal cortex (vMPFC) of the rat brain has been shown to induce anxiolytic-like effects in animal models based on associative learning. The role of this brain region in situations involving innate fear, however, is still poorly understood, with several contradictory results in the literature. The objective of the present work was to verify in male Wistar rats the effects of vMPFC administration of cobalt chloride (CoCl(2)), a selective inhibitor of synaptic activity, in rats submitted to two models based on innate fear, the elevated plus-maze (EPM) and light-dark box (LOB), comparing the results with those obtained in two models involving associative learning, the contextual fear conditioning (CFC) and Vogel conflict (VCT) tests. The results showed that, whereas CoCl(2) induced anxiolytic-like effects in the CFC and VCT tests, it enhanced anxiety in rats submitted to the EPM and LOB. Together these results indicate that the vMPFC plays an important but complex role in the modulation of defensive-related behaviors, which seems to depend on the nature of the anxiety/fear inducing stimuli. (C) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Acute reversible inactivation of the ventral medial prefrontal cortex induces antidepressant-like effects in rats

The ventral medial prefrontal cortex (vMPFC) has direct connections to subcortical, diencephalic and brainstem structures that have been closely related to depression. However, studies aimed at investigating the role of the vMPFC in the neurobiology of depression have produced contradictory results. Moreover, the precise involvement of vMPFC anatomic subdivisions, the prelimbic(PL) and the infralimbic (IL) cortices, in regulating depressive-like behavior have been poorly investigated. The forced swimming test (FST) is a widely employed animal model aimed at detecting antidepressant-like effects. Therefore, to further investigate a possible involvement of the vMFPC in depressive-like behavior, rats bilaterally implanted with cannulae aimed at the PL or IL prefrontal cortices were submitted to 15 min of forced swimming (pre-test) followed, 24 h later, by a 5-min swimming session (test), where immobility time was registered. Synaptic transmission in these regions was temporarily inhibited using local microinjection of cobalt chloride at different periods of the experimental procedure (before or after the pre-test or before the test). PL inactivation decreased immobility time independently of the time of the injection. In the IL inactivation induced a significant antidepressant-like effect when performed immediately before the pre-test or before the test, but not after the pre-test. These results suggest that activation of the vMPFC is important for the behavioral changes observed in rats submitted to the FST. They further indicate that, although both the PL and IL cortices are involved in these effects, they may play different roles. (C) 2010 Elsevier B.V. All rights reserved.

Cannabinoid CB(1) receptors in the medial prefrontal cortex modulate the expression of contextual fear conditioning

The ventral portion of the medial prefrontal cortex (vMPFC) has been related to the expression of contextual fear conditioning. This study investigated the possible involvement of CB(1) receptors in this aversive response. Male Wistar rats were submitted to a contextual aversive conditioning session and 48 h later re-exposed to the aversive context in which freezing and cardiovascular responses (increase of arterial pressure and heart rate) were recorded. The expression of CB(1) receptor-mRNA in the vMPFC was also measured using real time-PCR. In the first experiment intra-vMPFC administration of the CB(1) receptor agonist anandamide (AEA, 5 pmol/200 nl) or the AEA transport inhibitor AM404 (50 pmol/200 nl) prior to re-exposure to the aversive context attenuated the fear-conditioned responses. These effects were prevented by local pretreatment with the CB(1) receptor antagonist AM251 (100 pmol/200 nl). Using the same conditioning protocol in another animal group, we observed that CB(1) receptor mRNA expression increased in the vMPFC 48 h after the conditioning session. Although AM251 did not cause any effect by itself in the first experiment, this drug facilitated freezing and cardiovascular responses when the conditioning session employed a lesser aversive condition. These results indicated that facilitation of cannabinoid-mediated neurotransmission in the vMPFC by local CB(1) receptor activation attenuates the expression of contextual fear responses. Together they suggest that local endocannabinoid-mediated neurotransmission in the vMPFC can modulate these responses.

FURTHER INSIGHTS TOWARD VITAMIN C DETERMINATION AND STABILITY. PROPOSAL OF A NEW QUANTIFICATION METHOD

This work aimed at an evaluation of the classical iodine method for quantification of vitamin C (L-ascorbic acid) in fruit juices, as well as at a search into the stability of this so popular vitamin under different conditions of pH, temperature and light exposition, in addition to a proposal of a new quantification method. Our results point to the persistent reversibility of the blue color of the starch-triiodide complex at the end point when using the classical iodine titration, and the overestimation of the true vitamin concentration in fruit juices. A new quantification method is proposed in order to overcome this problem. Surprising conclusions were obtained regarding the controversial stability of L-ascorbic acid toward atmospheric oxygen, at low pH, even in fruit juice and at room temperature, showing that the major problem concerned with aging of fruit juices is proliferation of microorganisms rather than expontaneous oxidation of L-ascorbic acid.