22 resultados para Radioisotopes in the body
Resumo:
The theory of diffusion in many-dimensional Hamiltonian system is applied to asteroidal dynamics. The general formulation developed by Chirikov is applied to the NesvornA1/2-Morbidelli analytic model of three-body (three-orbit) mean-motion resonances (Jupiter-Saturn-asteroid). In particular, we investigate the diffusion along and across the separatrices of the (5, -2, -2) resonance of the (490) Veritas asteroidal family and their relationship to diffusion in semi-major axis and eccentricity. The estimations of diffusion were obtained using the Melnikov integral, a Hadjidemetriou-type sympletic map and numerical integrations for times up to 10(8) years.
Resumo:
The corrosion resistance of Ti and Ti-6Al-4V was investigated through electrochemical impedance spectroscopy, EIS, potentiodynamic polarisation curves and UV-Vis spectrophotometry. The tests were done in Hank solution at 25 degrees C and 37 degrees C. The EIS measurements were done at the open circuit potential at specific immersion times. An increase of the resistance as a function of the immersion time was observed, for Ti (at 25 degrees C and 37 degrees C), and for Ti-6Al-4V (at 25 degrees C), which was interpreted as the formation and growth of a passive film on the metallic surfaces. (C) 2009 Elsevier Ltd. All rights reserved.
Resumo:
The workplace is a manageable community-based setting for ensuring proper nutrition. This study aimed to evaluate dietary quality and associated factors among adult workers at a cosmetics factory in the metropolitan area of Sao Paulo, Brazil. This factory was actively participating in the Brazilian Workers` Meal Program, which was created to ensure workers` nutritional health. In this cross-sectional study, data on 202 adult workers were assessed using questionnaires (sociodemographic, anthropometric, and lifestyle characteristics) administered during August and September 2006. Dietary intake, measured by 24-hour dietary recall, was used to calculate the modified Healthy Eating Index (HEI). A repeated administration of the 24-hour dietary recall was applied in a random subsample to calculate the modified HEI adjusted for the within-person variation in intake. Mean adjusted modified HEI scores were analyzed using multiple linear regression adjusted for energy. The mean adjusted modified HEI score was 72.3 +/- 8.0. The lowest adjusted modified HEI components scores were ""milk and dairy products"" (4.4 +/- 3.2) and ""sodium"" (3.7 +/- 3.1). Two percent of workers had ""poor diet"" (adjusted modified HEI score <51 points) and the majority (87%) had ""diet that needs modification"" (adjusted modified HEI score between 51 and 80), despite their participation in the meal program. Adjusted modified HEI scores were considerably higher for men (74.7 +/- 7.0) than for women (66.9 +/- 8.2) and for normal body mass index (calculated as kg/m(2)) (73.3 +/- 7.8) than for overweight/obese (70.9 +/- 8.1). Based on these results, the vast majority of workers were found to have diets that needed improvement. Individuals with higher-quality diets were more likely to have lower body mass index and to be male. J Am Diet Assoc. 2010;110:786-790.
Resumo:
The present study is part of an ongoing investigation into the characteristics of Myxozoan parasites of Brazilian freshwater fish and was carried out using morphology, histopathology and electron microscopy analysis. A new Myxosporea species (Henneguya pseudoplatystoma) is described causing an important reduction in gill function in the farmed pintado (a hybrid fish from a cross between Pseudoplatystoma corruscans and Pseudoplatystoma fasciatum), which is a commercially important South American catfish. From a total of 98 pintado juveniles from fish farms in the states of Sao Paulo and Mato Grosso do Sul (Brazil), 36 samples (36.7%) exhibited infection of the gill filaments. infection was intense, with several plasmodia occurring on a same gill filament. The plasmodia were white and measured up to 0.5 mm in length; mature spores were ellipsoidal in the frontal view, measuring 33.2 +/- 1.9 mu m in total length, 10.4 +/- 0.6 mu m in body length, 3.4 +/- 0.4 mu m in width and 22.7 +/- 1.7 mu m in the caudal process. The polar capsules were elongated, measuring 3.3 +/- 0.4 mu m in length and 1.0 +/- 0.1 mu m in width and the polar filaments had six to seven turns. Histopathological analysis revealed the parasite in the connective tissue of the gill filaments and lamella. No inflammatory process was observed, but the development of the plasmodia reduced the area of functional epithelium. Ultrastructural analyses revealed a single plasmodial wall, which was in direct contact with the host cells and had numerous projections in direction of the host cells as well as extensive pinocytotic canals. A thick layer (2-6 mu m) of fibrous material and numerous mitochondria were found in the ectoplasm. Generative cells and the earliest stage of sporogenesis were seen more internally. Advanced spore developmental stages and mature spores were found in the central portion of the plasmodia. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
A study of the potential role of aerosols in modifying clouds and precipitation is presented using a numerical atmospheric model. Measurements of cloud condensation nuclei (CCN) and cloud size distribution properties taken in the southwestern Amazon region during the transition from dry to wet seasons were used as guidelines to define the microphysical parameters for the simulations. Numerical simulations were carried out using the Brazilian Development on Regional Atmospheric Modeling System, and the results presented considerable sensitivity to changes in these parameters. High CCN concentrations, typical of polluted days, were found to result in increases or decreases in total precipitation, depending on the level of pollution used as a reference, showing a complexity that parallels the aerosol-precipitation interaction. Our results show that on the grids evaluated, higher CCN concentrations reduced low-to-moderate rainfall rates and increased high rainfall rates. The principal consequence of the increased pollution was a change from a warm to a cold rain process, which affected the maximum and overall mean accumulated precipitation. Under polluted conditions, cloud cover diminished, allowing greater amounts of solar radiation to reach the surface. Aerosol absorption of radiation in the lower layers of the atmosphere delayed convective evolution but produced higher maximum rainfall rates due to increased instability. In addition, the intensity of the surface sensible heat flux, as well as that of the latent heat flux, was reduced by the lower temperature difference between surface and air, producing greater energy stores at the surface.
Resumo:
Various authors have suggested that the gamma-ray burst (GRB) central engine is a rapidly rotating, strongly magnetized, (similar to 10(15)-10(16) G) compact object. The strong magnetic field can accelerate and collimate the relativistic flow and the rotation of the compact object can be the energy source of the GRB. The major problem in this scenario is the difficulty of finding an astrophysical mechanism for obtaining such intense fields. Whereas, in principle, a neutron star could maintain such strong fields, it is difficult to justify a scenario for their creation. If the compact object is a black hole, the problem is more difficult since, according to general relativity it has ""no hair"" (i.e., no magnetic field). Schuster, Blackett, Pauli, and others have suggested that a rotating neutral body can create a magnetic field by non-minimal gravitational-electromagnetic coupling (NMGEC). The Schuster-Blackett form of NMGEC was obtained from the Mikhail and Wanas`s tetrad theory of gravitation (MW). We call the general theory NMGEC-MW. We investigate here the possible origin of the intense magnetic fields similar to 10(15)-10(16) G in GRBs by NMGEC-MW. Whereas these fields are difficult to explain astrophysically, we find that they are easily explained by NMGEC-MW. It not only explains the origin of the similar to 10(15)-10(16) G fields when the compact object is a neutron star, but also when it is a black hole.
Resumo:
A semi-detailed gravity survey was carried out over an area of 650 km(2) localized in the Eo-Neoproterozoic coastal zone of Paraiba State where 548 new gravity stations were added to the existing database. Gravity measurements were made with a LaCoste and Romberg model G meter with a precision of 0.04 mGal. The altitude was determined by barometric levelling with a fixed base achieving a 1.2 m measure of uncertainty, corresponding to an overall accuracy of 0.24 mGal for the Bouguer anomaly. The residual Bouguer map for a 7th degree regional polynomial showed a circumscribed negative anomaly coincident with a localized aero-magnetic anomaly and with hydro-thermally altered outcrops, near the city of Itapororoca. The 3D gravity modelling, constrained by geologic mapping was interpreted as a low density, fractured and/or altered material with a most probable volume of approximately 23 km(3), extending to about 8,500 m depth. This result is in accordance with a volcanic body associated with hydrothermal processes accompanied by surface mineralization evidence, which may be of interest to the mining industry.
Resumo:
The objectives of this study were: (1) to test the existence of an aggregation pheromone in the gregarious psocid Cerastipsocus sivorii; (2) to compare the attractiveness of odors from different aggregations; (3) to test whether nymphs are able to chemically recognize damage-released alarm signals. In a choice experiment conducted in the laboratory, we showed that psocids are able to detect chemical cues from groups of conspecifics. Laboratory experiments also showed that nymphs are capable of chemically recognizing the aggregations where they came from. Finally, in a field experiment, most aggregations dispersed when exposed to the body fluids of a crushed conspecific, but no aggregations dispersed upon exposure to a crushed termite. The implications of these results for the evolution of sociality in psocopterans are discussed.
Resumo:
A new species of keel-headed amphisbaenian of the genus Anops is described from the Cerrado of the Jalapao region, Tocantins state, Brazil. This new species of Anops is described from a single specimen, which may be easily distinguished from the other species of the genus, Anops bilabialatus and Anops kingii, by showing an extremely narrow head (37.2% head length); a row of eight occipitals anterior to the first body annulus; temporal present, mental and postmental fused; four postgenial rows located between the malars; and two malars posterior to the second infralabial. The new species is the first of the genus found in the Cerrado core area, and, based on the available records, the single species in the genus may be restricted to this region.
Resumo:
Proline-specific dipeptidyl peptidases are emerging as a protease family with important roles in the regulation of signaling by peptide hormones related to energy balance. The treatment of neonatal rats with monosodium glutamate (MSG) is known to produce a selective damage on the arcuate nucleus with development of obesity. This study investigates the relationship among dipeptidyl peptidase IV (DPPIV) hydrolyzing activity, CD26 protein, fasting, and MSG model of obesity in 2 areas of the central nervous system. Dipeptidyl peptidase IV and CD26 were, respectively, evaluated by fluorometry, and enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction in soluble (SF) and membrane-bound (MF) fractions from the hypothalamus and hippocampus of MSG-treated and normal rats, submitted or not to food deprivation (FD). Dipeptidyl peptidase IV in both areas was distinguished kinetically as insensitive (DI) and sensitive (DS) to diprotin A. Compared with the controls, MSG and/or FD decreased the activity of DPPIV-DI in the SF and MF from the hypothalamus, as well as the activity of DPPIV-DS in the SF from the hypothalamus and in the MF from the hippocampus. Monosodium glutamate and/or FD increased the activity of DPPIV-DI in the MF from the hippocampus. The monoclonal protein expression of membrane CD26 by enzyme-linked immunosorbent assay decreased in the hypothalamus and increased in the hippocampus of MSG and/or FD relative to the controls. The existence of DPPIV-like activity with different sensitivities to diprotin A and the identity of insensitive with CD26 were demonstrated for the first time in the central nervous system. Data also demonstrated the involvement of DPPIV-DI/CD26 hydrolyzing activity in the energy balance probably through the regulation of neuropeptide Y and beta-endorphin levels in the hypothalamus and hippocampus. (C) 2011 Elsevier Inc. All rights reserved.
Resumo:
We describe the advertisement call, tadpole, karyotype, and additional information on the natural history of Cycloramphus lutzorum from southern Brazil. Sonograms were generated from digitally recorded calls. Tadpoles were collected in the field for description in the lab, and an adult was collected for karyotyping. Data on seasonal activity were gathered monthly from November 2005 to November 2007. All tadpoles (N = 21), juveniles (N = 18), and adults (N = 52) were found exclusively in streams. Reproduction, as identified by calling frogs, occurred from July through November. Frogs call all day long, but mostly at dusk, from rock crevices inside the stream edges near the splash zone. The call is short and loud, with 11 pulsed notes, of 491-641 ms, with a dominant frequency of 0.98-1.39 kHz. We describe the exotrophic and semiterrestrial tadpoles, always found in constantly humid vertical rock walls in the stream. Tadpoles of C. lutzorum are recognized by differences in labial tooth row formula, eye diameter, body shape, position of nares, and development of tail. Like congeneric species, the karyotype of C. lutzorum comprises 26 metacentric and submetacentric chromosomes. Cycloramphus lutzorum is restricted to and adapted for living in fast flowing streams, many of which are threatened by deforestation, pollution, and habitat loss. Therefore, we recommend the status of C. lutzorum be changed from its current ""Data Deficient"" to ""Near Threatened (NT)"" in the IUCN species red list.
Resumo:
Little is known about insect intestinal sugar absorption, in spite of the recent findings, and even less has been published regarding water absorption. The aim of this study was to shed light on putative transporters of water and glucose in the insect midgut Glucose and water absorptions by the anterior ventriculus of Dysdercus peruvianus midgut were determined by feeding the insects with a glucose and a non-absorbable dye solution, followed by periodical dissection of insects and analysis of ventricular contents. Glucose absorption decreases glucose/dye ratios and water absorption increases dye concentrations. Water and glucose transports are activated (water 50%, glucose 33%) by 50 mM K(2)SO(4) and are inhibited (water 46%, glucose 82%) by 0.2 mM phloretin, the inhibitor of the facilitative hexose transporter (GLUT) or are inhibited (water 45%, glucose 35%) by 0.1 mM phlorizin, the inhibitor of the Na(+)-glucose cotransporter (SGLT). The results also showed that the putative SGLT transports about two times more water relative to glucose than the putative GLUT. These results mean that D. peruvianus uses a GLUT-like transporter and an SGLT-like transporter (with K(+) instead of Na(+)) to absorb dietary glucose and water. A cDNA library from D. peruvianus midgut was screened and we found one sequence homologous to GLUT1, named DpGLUT, and another to a sodium/solute symporter, named DpSGLT. Semi-quantitative RT-PCR studies revealed that DpGLUT and DpSGLTs mRNA were expressed in the anterior midgut, where glucose and water are absorbed, but not in fat body, salivary gland and Malpighian tubules. This is the first report showing the involvement of putative GLUT and SGLT in both water and glucose midgut absorption in insects. (C) 2010 Elsevier Inc. All rights reserved.
Resumo:
The moss Tayloria dubyi (Splachnaceae) is endemic to the subantarctic Magallanes ecoregion where it grows exclusively on bird dung and perhaps only on feces of the goose Chloephaga picta, a unique habitat among Splachnaceae. Some species of Splachnaceae from the Northern Hemisphere are known to recruit coprophilous flies as a vector to disperse their spores by releasing intense odors mimicking fresh clung or decaying corpses. The flies land on the capsule, and may get in contact with the protruding mass of spores that stick to the insect body. The dispersal strategy relies on the spores falling off when the insect reaches fresh droppings or carrion. Germination is thought to be rapid and a new population is quickly established over the entire substrate. The objectives of this investigation were to determine whether the coprophilous T. dubyi attracts flies and to assess the taxonomic diversity of the flies visiting this moss. For this, fly traps were set up above mature sporophyte bearing populations in two peatlands on Navarino Island. We captured 64 flies belonging to the Muscidae (Palpibracus chilensis), Tachinidae (Dasyuromyia sp) and Sarcophagidae (not identified to species) above sporophytes of T. dubyi, whereas no flies were captured in control traps set up above Sphagnum mats nearby.
Resumo:
Protein (western blotting) and gene (PCR) expressions, catalytic activity of puromycin-insensitive membrane-bound neutral aminopeptidase (APM/CD13) and in situ regional distribution of CD13 and FOS immunoreactivity (it) were evaluated in the hypothalamus of monosodium glutamate obese (MSG) and/or food deprived (FD) rats in order to investigate their possible interplay with metabolic functions. Variations in protein and gene expressions of CD13 relative to controls coincided in the hypothalamus of MSG and MSG-FD (decreased 2- to 17-fold). Compared with controls, the reduction of hypothalamic CD13 content reflected a negative balance in its regional distribution in the supraoptic, paraventricular, periventricular and arcuate nuclei. CD13-ir increased in the supraoptic nucleus in MSG (2.5-fold) and decreased in the paraventricular nucleus (2-fold) together with FOS-ir (1.5-fold) in FD. In MSG-FD. FOS-ir decreased (7-fold) in the paraventricular nucleus, while CD13-ir decreased in the periventricular (5.6-fold) and the arcuate (3.7-fold) nuclei. It was noteworthy that all these changes of CD13 were not related to catalytic activity of APM. Data suggested that hypothalamic CD13 plays a role in the regulation of energy metabolism not by means of APM enzyme activity. (c) 2010 Elsevier B.V. All rights reserved.
Resumo:
Damage following ischemia and reperfusion (I/R) is common in the intestine and can be caused during abdominal surgery, in several disease states and following intestinal transplantation. Most studies have concentrated on damage to the mucosa, although published evidence also points to effects on neurons. Moreover, alterations of neuronally controlled functions of the intestine persist after I/R. The present study was designed to investigate the time course of damage to neurons and the selectivity of the effect of I/R damage for specific types of enteric neurons. A branch of the superior mesenteric artery supplying the distal ileum of anesthetised guinea pigs was occluded for 1 h and the animals were allowed to recover for 2 h to 4 weeks before tissue was taken for the immunohistochemical localization of markers of specific neuron types in tissues from sham and I/R animals. The dendrites of neurons with nitric oxide synthase (NOS) immunoreactivity, which are inhibitory motor neurons and interneurons, were distorted and swollen by 24 h after I/R and remained enlarged up to 28 days. The total neuron profile areas (cell body plus dendrites) increased by 25%, but the sizes of cell bodies did not change significantly. Neurons of type II morphology (intrinsic primary afferent neurons), revealed by NeuN immunoreactivity, were transiently reduced in cell size, at 24 h and 7 days. These neurons also showed signs of minor cell surface blebbing. Calretinin neurons, many of which are excitatory motor neurons, were unaffected. Thus, this study revealed a selective damage to NOS neurons that was observed at 24 h and persisted up to 4 weeks, without a significant change in the relative numbers of NOS neurons.