O desafio da delimitação de áreas de preservação permanente

A demarcação das áreas de proteção no topo de morros e ao longo dos divisores d'água é um processo complexo, dificultando a fiscalização e, por conseguinte, o fiel cumprimento da legislação. Como alternativa aos métodos tradicionalmente utilizados - mapas topográficos, levantamentos de campo e uso dos restituidores - na execução dessa tarefa, apresenta-se uma nova metodologia, alicerçada na modelagem numérica do relevo e implementada em um sistema de informações geográficas. O processo é todo automatizado e alicerça-se em um conceito relativamente novo de modelos digitais de elevação hidrologicamente consistentes, tendo como vantagens a confiabilidade e a reprodutibilidade dos resultados obtidos, além da economia óbvia de tempo e mão-de-obra. A partir da disponibilização gratuita pela NASA dos dados SRTM (Shuttle Radar Topography Mission) para todo o continente americano, os resultados indicaram claramente que a aplicação da Lei Florestal no Brasil passa a ser tão-somente uma vontade política.

Relações entre qualidade da água e uso do solo em Goiás: uma análise à escala da bacia hidrográfica

Este trabalho teve por objetivo principal investigar possíveis relações entre qualidade da água e uso do solo em bacias hidrográficas de abastecimento público em Goiás. Nesse sentido, foram compilados dados de 174 captações, operadas pelo Saneamento de Goiás entre janeiro/2002 e dezembro/2004. Médias anuais de seca e de cheia, de turbidez, cor aparente, pH, cloretos e índices de coliforme total e fecal foram relacionadas, por análise de componentes principais, em um índice de qualidade de água (IQA). Com base no mapa de cobertura e uso do solo de Goiás, à escala de 1:250.000, e um mosaico de imagens SRTM (Shuttle Radar Topography Mission), foram delimitadas as bacias de 89 das captações, para as quais foi calculado um Índice Normalizado de Vegetação Remanescente (NRVI). Cor aparente, turbidez, pH, ICT e ICF estiveram aquém dos padrões legalmente requeridos em até 62,43% das captações analisadas, principalmente nos períodos de cheia, quando os piores valores de IQA são observados. Os resultados indicaram que o IQA utilizado é sensível às variações sazonais e responde ao aporte de sedimentos e matéria orgânica por escoamento superficial. Da mesma forma, esse índice se relaciona, ainda que de forma tênue, às variações regionais nos valores de NRVI. Assim, novos estudos, levando-se em conta outros parâmetros de qualidade da água (como nitrogênio e fósforo) e diferentes escalas da paisagem (ex. zona ripária), são necessários, com vistas a uma melhor determinação dessas relações.

Delimitação automática de bacias hidrográficas utilizando dados SRTM

A delimitação adequada de bacias hidrográficas é fundamental por ser essa a unidade territorial para fins de planejamento e de gerenciamento dos recursos hídricos. Desse modo, este trabalho teve objetivo de analisar uma metodologia de delimitação automática de bacias hidrográficas. Foram utilizados, para tanto, dados do projeto Shuttle Radar Topographic Mission (SRTM) integrados e processados em Sistema de Informações Geográficas (SIG). Os resultados confirmam valores de área compatíveis aos obtidos com base em cartas topográficas. Assim, a automatização da delimitação de bacias hidrográficas, por meio de dados do SRTM e ambiente SIG, apresenta-se vantajosa em relação ao custo e benefício proporcionado, além de estabelecer a padronização do traçado e posterior minimização de conflitos quanto à fixação da unidade de gestão dos recursos hídricos.

Comparison between hydrographically conditioned digital elevation models in the morphometric charaterization of watersheds

The aim of this study was to compare the hydrographically conditioned digital elevation models (HCDEMs) generated from data of VNIR (Visible Near Infrared) sensor of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), of SRTM (Shuttle Radar Topography Mission) and topographical maps from IBGE in a scale of 1:50,000, processed in the Geographical Information System (GIS), aiming the morphometric characterization of watersheds. It was taken as basis the Sub-basin of São Bartolomeu River, obtaining morphometric characteristics from HCDEMs. Root Mean Square Error (RMSE) and cross validation were the statistics indexes used to evaluate the quality of HCDEMs. The percentage differences in the morphometric parameters obtained from these three different data sets were less than 10%, except for the mean slope (21%). In general, it was observed a good agreement between HCDEMs generated from remote sensing data and IBGE maps. The result of HCDEM ASTER was slightly higher than that from HCDEM SRTM. The HCDEM ASTER was more accurate than the HCDEM SRTM in basins with high altitudes and rugged terrain, by presenting frequency altimetry nearest to HCDEM IBGE, considered standard in this study.

Aspectos endoscópicos no manejo da úlcera péptica gastroduodenal

Bleeding remains a common and a potential lethal complication for peptic ulcer disease. Multidisciplinary approach by endoscopists, surgeons and intensive care physicians is necessary to improve results for this severe complication. In this article we intend to introduce surgeons and intensive care physicians to endoscopic concepts and maneuvers commonly used in the treatment of bleeding peptic ulcer disease. Early clinical assessment and endoscopic evaluation are helpful to classify the severity of the bleeding episode. Two major achievements have changed the management of this complication: combined endoscopic therapy and proton pump inhibitors. The former consists of combining two different endoscopic methods to stop bleeding or prevent re-bleeding (e.g., injection of a sclerosing substance and thermal coagulation). Surgical treatment for peptic ulcer bleeding is indicated when endoscopic therapy fails or to prevent re-bleeding in high risk patients who presents with a spurting bleeding ulcer and shock. For the remaining situations, there are consistent evidences that a second endoscopic therapy should be attempted when re-bleeding occurs. Keywords: endoscopic hemostasis, recurrent bleeding, peptic ulcer bleeding, proton-pump inhibitor, non-variceal gastrointestinal bleeding.

Esophagectomy with gastroplasty in advanced megaesophagus: late results of omeprazole use

Objective: To analyze the late results of advanced Chagasic megaesophagus treatment by esophagectomy associated with the use of proton pump inhibitor (omeprazole) as for the incidence of esophagitis and Barrett's esophagus in the remaining stump. Methods : We studied patients with advanced megaesophagus undergoing esophagectomy and transmediastinal esophagogastroplasty. Patients were divided into three groups: A (20) with esophageal replacement by full stomach, without the use of omeprazole; B (20) with esophageal replacement by full stomach, with omeprazole 40 mg/day introduced after the first postoperative endoscopy and maintained for six years; and C (30) with esophageal replacement by gastric tube with use of omeprazole. Dysphagia, weight loss and BMI were clinical parameters we analyzed. Upper gastrointestinal endoscopy was performed in all patients, and determined the height of the anastomosis, the aspect of the mucosa, with special attention to possible injuries arising from gastroesophageal reflux, and the patency of the esophagogastric anastomosis. Results : We studied 50 patients, 28 males (56%) and 22 (44%) females. All underwent endoscopy every year. In the first endoscopy, erosive esophagitis was present in nine patients (18%) and Barrett's esophagus, in four (8%); in the last endoscopy, erosive esophagitis was present in five patients (8%) and Barrett's esophagus in one (2%). When comparing groups B and C, there was no evidence that the manufacturing of a gastric tube reduced esophagitis and Barrett's esophagus. However, when comparing groups A and C, omeprazole use was correlated with reduction of reflux complications such as esophagitis and Barrett's esophagus (p <0.005). Conclusion : The use of omeprazole (40 mg/day) reduced the onset of erosive esophagitis and Barrett's esophagus during the late postoperative period.

Effects of entorhinal cortex lesions on memory in different tasks

Lesions of the entorhinal cortex produce retrograde memory impairment in both animals and humans. Here we report the effects of bilateral entorhinal cortex lesions caused by the stereotaxic infusion of N-methyl-D-aspartate (NMDA) in rats at two different moments, before or after the training session, on memory of different tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Pre- or post-training entorhinal cortex lesions caused an impairment of performance in the shuttle avoidance task, which agrees with the previously described role of this area in the processing of memories acquired in successive sessions. In the inhibitory avoidance task, only the post-training lesions had an effect (amnesia). No effect was observed on the open field task. The findings suggest that the role of the entorhinal cortex in memory processing is task-dependent, perhaps related to the complexity of each task

Effects of naltrexone and cross-tolerance to morphine in a learned helplessness paradigm

Opiates have been implicated in learned helplessness (LH), a phenomenon known to be related to opiate stress-induced analgesia (SIA). In the present study, we investigated the role of opiates in the induction of LH and SIA under different conditions. Adult female Wistar rats were trained either by receiving 60 inescapable 1-mA footshocks (IS group, N = 114) or by confinement in the shock box (control or NS group, N = 92). The pain threshold of some of the animals was immediately evaluated in a tail-flick test while the rest were used 24 h later in a shuttle box experiment to examine their escape performance. The opiate antagonist naltrexone (0 or 8 mg/kg, ip) and the previous induction of cross-tolerance to morphine by the chronic administration of morphine (0 or 10 mg/kg, sc, for 13 days) were used to identify opiate involvement. Analysis of variance revealed that only animals in the IS group demonstrated antinociception and an escape deficit, both of which were resistant to the procedures applied before the training session. However, the escape deficit could be reversed if the treatments were given before the test session. We conclude that, under our conditions, induction of the LH deficit in escape performance is not opiate-mediated although its expression is opiate-modulated

Signaled two-way avoidance learning using electrical stimulation of the inferior colliculus as negative reinforcement: effects of visual and auditory cues as warning stimuli

The inferior colliculus is a primary relay for the processing of auditory information in the brainstem. The inferior colliculus is also part of the so-called brain aversion system as animals learn to switch off the electrical stimulation of this structure. The purpose of the present study was to determine whether associative learning occurs between aversion induced by electrical stimulation of the inferior colliculus and visual and auditory warning stimuli. Rats implanted with electrodes into the central nucleus of the inferior colliculus were placed inside an open-field and thresholds for the escape response to electrical stimulation of the inferior colliculus were determined. The rats were then placed inside a shuttle-box and submitted to a two-way avoidance paradigm. Electrical stimulation of the inferior colliculus at the escape threshold (98.12 ± 6.15 (A, peak-to-peak) was used as negative reinforcement and light or tone as the warning stimulus. Each session consisted of 50 trials and was divided into two segments of 25 trials in order to determine the learning rate of the animals during the sessions. The rats learned to avoid the inferior colliculus stimulation when light was used as the warning stimulus (13.25 ± 0.60 s and 8.63 ± 0.93 s for latencies and 12.5 ± 2.04 and 19.62 ± 1.65 for frequencies in the first and second halves of the sessions, respectively, P<0.01 in both cases). No significant changes in latencies (14.75 ± 1.63 and 12.75 ± 1.44 s) or frequencies of responses (8.75 ± 1.20 and 11.25 ± 1.13) were seen when tone was used as the warning stimulus (P>0.05 in both cases). Taken together, the present results suggest that rats learn to avoid the inferior colliculus stimulation when light is used as the warning stimulus. However, this learning process does not occur when the neutral stimulus used is an acoustic one. Electrical stimulation of the inferior colliculus may disturb the signal transmission of the stimulus to be conditioned from the inferior colliculus to higher brain structures such as amygdala

Effect of repeated restraint stress on memory in different tasks

The present study investigated the effect of repeated stress applied to female rats on memory evaluated by three behavioral tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Repeated stress had different effects on rat behavior when different tasks were considered. In the two-way active avoidance test the stressed animals presented memory of the task, but their memory scores were impaired when compared to all other groups. In the habituation to the open field, only the control group showed a significant difference in the number of rearings between training and testing sessions, which is interpreted as an adequate memory of the task. In the handled and chronically stressed animals, on the other hand, no memory was observed, suggesting that even a very mild repeated stress would be enough to alter habituation to this task. The performance in the inhibitory avoidance task presented no significant differences between groups. The findings suggest that repeated restraint stress might induce cognitive impairments that are dependent on the task and on stress intensity.

Uptake of NO-releasing drugs by the P2 nucleoside transporter in trypanosomes

Nitric oxide (NO·) has been identified as a principal regulatory molecule of the immune system and the major cytotoxic mediator of activated immune cells. NO· can also react rapidly with a variety of biological species, particularly with the superoxide radical anion O2·- at almost diffusion-limited rates to form peroxynitrite anion (ONOO-). ONOO- and its proton-catalyzed decomposition products are capable of oxidizing a great diversity of biomolecules and can act as a source of toxic hydroxyl radicals. As a consequence, a strategy for the development of molecules with potential trypanocidal activities could be developed to increase the concentration of nitric oxide in the parasites through NO·-releasing compounds. In this way, the rate of formation of peroxynitrite from NO· and O2·- would be faster than the rate of dismutation of superoxide radicals by superoxide dismutases which constitute the primary antioxidant enzymatic defense system in trypanosomes. The adenosine transport systems of parasitic protozoa, which are also in certain cases implicated in the selective uptake of active drugs such as melarsoprol or pentamidine, could be exploited to specifically target these NO·-releasing compounds inside the parasites. In this work, we present the synthesis, characterization and biological evaluation of a series of molecules that contain both a group which would specifically target these drugs inside the parasites via the purine transporter, and an NO·-donor group that would exert a specific pharmacological effect by increasing NO level, and thus the peroxynitrite concentration inside the parasite.

Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

Cyanide-resistant alternative oxidase (AOX) is not limited to plant mitochondria and is widespread among several types of protists. The uncoupling protein (UCP) is much more widespread than previously believed, not only in tissues of higher animals but also in plants and in an amoeboid protozoan. The redox energy-dissipating pathway (AOX) and the proton electrochemical gradient energy-dissipating pathway (UCP) lead to the same final effect, i.e., a decrease in ATP synthesis and an increase in heat production. Studies with green tomato fruit mitochondria show that both proteins are present simultaneously in the membrane. This raises the question of a specific physiological role for each energy-dissipating system and of a possible functional connection between them (shared regulation). Linoleic acid, an abundant free fatty acid in plants which activates UCP, strongly inhibits cyanide-resistant respiration mediated by AOX. Moreover, studies of the evolution of AOX and UCP protein expression and of their activities during post-harvest ripening of tomato fruit show that AOX and plant UCP work sequentially: AOX activity decreases in early post-growing stages and UCP activity is decreased in late ripening stages. Electron partitioning between the alternative oxidase and the cytochrome pathway as well as H+ gradient partitioning between ATP synthase and UCP can be evaluated by the ADP/O method. This method facilitates description of the kinetics of energy-dissipating pathways and of ATP synthase when state 3 respiration is decreased by limitation of oxidizable substrate.

Important amino acid residues of potato plant uncoupling protein (StUCP)

Chemical modifications were used to identify some of the functionally important amino acid residues of the potato plant uncoupling protein (StUCP). The proton-dependent swelling of potato mitochondria in K+-acetate in the presence of linoleic acid and valinomycin was inhibited by mersalyl (Ki = 5 µM) and other hydrophilic SH reagents such as Thiolyte MB, iodoacetate and 5,5'-dithio-bis-(2-nitrobenzoate), but not by hydrophobic N-ethylmaleimide. This pattern of inhibition by SH reagents was similar to that of brown adipose tissue uncoupling protein (UCP1). As with UCP1, the arginine reagent 2,3-butadione, but not N-ethylmaleimide or other hydrophobic SH reagents, prevented the inhibition of StUCP-mediated transport by ATP in isolated potato mitochondria or with reconstituted StUCP. The results indicate that the most reactive amino acid residues in UCP1 and StUCP are similar, with the exception of N-ethylmaleimide-reactive cysteines in the purine nucleotide-binding site.

Pressure-assisted cold denaturation of hen egg white lysozyme: the influence of co-solvents probed by hydrogen exchange nuclear magnetic resonance

COSY proton nuclear magnetic resonance was used to measure the exchange rates of amide protons of hen egg white lysozyme (HEWL) in the pressure-assisted cold-denatured state and in the heat-denatured state. After dissolving lysozyme in deuterium oxide buffer, labile protons exchange for deuterons in such a way that exposed protons are substituted rapidly, whereas "protected" protons within structured parts of the protein are substituted slowly. The exchange rates k obs were determined for HEWL under heat treatment (80ºC) and under high pressure conditions at low temperature (3.75 kbar, -13ºC). Moreover, the influence of co-solvents (sorbitol, urea) on the exchange rate was examined under pressure-assisted cold denaturation conditions, and the corresponding protection factors, P, were determined. The exchange kinetics upon heat treatment was found to be a two-step process with initial slow exchange followed by a fast one, showing residual protection in the slow-exchange state and P-factors in the random-coil-like range for the final temperature-denatured state. Addition of sorbitol (500 mM) led to an increase of P-factors for the pressure-assisted cold denatured state, but not for the heat-denatured state. The presence of 2 M urea resulted in a drastic decrease of the P-factors of the pressure-assisted cold denatured state. For both types of co-solvents, the effect they exert appears to be cooperative, i.e., no particular regions within the protein can be identified with significantly diverse changes of P-factors.

Effect of Helicobacter pylori infection and acid blockade by lansoprazole on clarithromycin bioavailability

The effect of proton pump inhibitors and Helicobacter pylori infection on the bioavailability of antibiotics is poorly understood. We determined the effects of 5-day oral administration of 60 mg lansoprazole on the bioavailability of clarithromycin in individuals with and without H. pylori infection. Thirteen H. pylori-infected and 10 non-infected healthy volunteers were enrolled in a study with an open-randomized two-period crossover design and a 21-day washout period between phases. Plasma concentrations of clarithromycin in subjects with and without lansoprazole pre-treatment were measured by liquid chromatography coupled to a tandem mass spectrometer. Clarithromycin Cmax and AUC0-10 h were significantly reduced after lansoprazole administration. In addition, lansoprazole treatment of the H. pylori-positive group resulted in a statistically significant greater reduction in Cmax (40 vs 15%) and AUC0-10 h (30 vs 10%) compared to lansoprazole-treated H. pylori-negative subjects. Thus, treatment with lansoprazole for 5 days reduced bioavailability of clarithromycin, irrespective of H. pylori status. This reduction, however, was even more pronounced in H. pylori-infected individuals.