Changes in ichthyofauna composition along a gradient from clearwaters to blackwaters in coastal streams of Atlantic forest (southeastern Brazil) in relation to environmental variables

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Changes in lipid composition in hippocampus early and late after status epilepticus induced by kainic acid in wistar rats

Oxidative damage to biological membranes has been reported as a cause of alterations in many different diseases. We had previously reported lipid peroxidation in the kainic acid model of temporal epilepsy. In this study we evaluated earlier and later modifications in the lipid composition after status epileticus induced by kainic acid. Lipid composition was determined by thin-layer chromatography, in the cortex and hippocampus 12-14 h, 7-8, 75-80, or 140-150 days after the end of status epileticus. In the hippocampus there was a significant change in the lipid protein ratio after status epileticus and this was accompanied by an alteration in lipid composition in all tested times. These results suggested that lipid peroxidation induced by kainic acid could be accompanied by chronic changes in the lipid composition that could be related to the development of seizures.

Changes in plant species composition and functional traits along the successional trajectory of a restored patch of Atlantic Forest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term changes in handgrip strength, body composition, and lymphedema induced by breast cancer surgery

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Changes in maternal body composition and metabolism of dairy goats during pregnancy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessing the dynamic of structural changes in Cerrado vegetation of protected and non-protected areas using NDVI

The structure of Brazilian savannah, named locally as “cerrado”, tends to change if the human pressures, such as pasture and intensive fire, are suppressed showing a densification of the physiognomies throughout the time. Vegetation Index acquired from remotely sensed data has been a proper way to study and monitoring large areas, and the Normalized Difference Vegetation Index (NDVI) is one of the most used for this purpose. The aim of this study was to assess the dynamic of structural changes in protected and non-protected areas of cerrado vegetation using NDVI. For this purpose, three cerrado fragments in the state of São Paulo, Brazil, were evaluated for a 26 year time span from 1985 and 2011, being two of them protected against anthropogenic interference. Landsat 5 –Thematic Mapper images were used and processed in ArcGIS. In the protected areas NDVI indicated that the vegetation followed the expected trend of changes for cerrado, with more open physiognomies tending to be denser throughout this period of 26 years, whereas in the non-protected fragment the NDVI evidences human pressure, showing lower phytomass in 2011. NDVI showed to be efficient in detecting and monitoring changes in cerrado vegetation structure, and can be useful to study both, the natural dynamics of cerrado vegetation and the anthropogenic interference in protected areas.

Temporal changes in benthic megafaunal abundance and composition across the West Antarctic Peninsula shelf: Results from video surveys

The West Antarctic Peninsula (WAP) shelf experiences intense seasonal and interannual variability in phytoplankton production and particulate-organic-carbon flux to the seafloor. To explore the response of the megabenthic community to this production variability, we conducted video surveys of epibenthic megafauna at three stations on the WAP shelf in Nov-Dec 1999, Mar 2000, Jun 2000, Oct-Nov 2000, and Feb-Mar 2001. The epibenthic megafauna was dominated (>90%) by elasipod holothurians, irregular urchins and anthozoans, with total abundances ranging from 19 to 152 ind. 1 00 m(-2). The abundance of three of the dominant taxa (Protelpidia murrayi, Peniagone vignomi, and Amphipneustes spp.) varied significantly across seasons (p <0.05), although variations were not tightly correlated with the summer bloom cycle. The irregular urchins in the genus Amphipneustes varied 5-fold in abundance at single stations, with maximum densities (an average of 10.1 ind. 100 m(-2)) attained in Jun 2000. Abundances of the elasipod holothurians P. murrayi (1-121 ind. 100 m(-2)) and P. vignoni (0.7-27.5 ind. 100 m(-2)) fell within the range for elasipod holothurians from other bathyal regions measured using image analysis. The abundance of P. murrayi increased up to 6-fold from a single Jun-Oct recruitment pulse, while changes in the abundance of P. vignoni (over 2-fold higher in Feb-Mar 2001) apparently resulted from immigration during the presence of a 1-2 cm thick carpet of fresh phytocletritus. Based on the ratio of the number of fecal casts per individual, elasipod holothurians increased surface-deposit feeding rates by >= 2-fold while phytocletritus was present at the seafloor. Nonetheless, these surface-deposit feeders appeared to feed and egest sediments throughout the winter, which is consistent with year-round persistence of a labile food bank in surficial sediments on the deep WAP shelf.

Seasonal changes in the pigment composition of natural population of Gracilaria domingensis (Gracilariales, Rhodophyta)

The concentrations of phycobiliproteins (phycoerythrin and phycocyanin), chlorophyll-a and total soluble proteins were determined monthly in three strains (red, green and brown) of Gracilaria domingensis (Kützing) Sonder ex Dickie, collected from natural populations on the coast of Rio Grande do Norte, Brazil. In all the strains, pigment and protein concentrations were higher in the months of less sunlight and greater nitrogen availability and decreased gradually with increased sunlight and decreased nutrient concentration. The red strain showed higher concentrations of phycoerythrin and total soluble proteins. The difference in the concentration of biochemical components over the course of the year indicates species acclimation to different environmental conditions.

Sensitivity of Nd isotopic composition in seawater to changes in Nd sources and paleoceanographic implications

It has been argued that past changes in the sources of Nd could hamper the use of the Nd isotopic composition (ϵNd) as a proxy for past changes in the overturning of deep water masses. Here we reconsider uncertainties associated with ϵNd in seawater due to potential regional to global scale changes in the sources of Nd by applying a modeling approach. For illustrative purposes we describe rather extreme changes in the magnitude of source fluxes, their isotopic composition or both. We find that the largest effects on ϵNd result from changes in the boundary source. Considerable changes also result from variations in the magnitude or ϵNd of dust and rivers but are largely constrained to depths shallower than 1 km, except if they occur in or upstream of regions where deep water masses are formed. From these results we conclude that changes in Nd sources have the potential to affect ϵNd. However, substantial changes are required to generate large-scale changes inϵNd in deep water that are similar in magnitude to those that have been reconstructed from sediment cores or result from changes in meridional overturning circulation in model experiments. Hence, it appears that a shift in ϵNdcomparable to glacial-interglacial variations is difficult to obtain by changes in Nd sources alone, but that more subtle variations can be caused by such changes and must be interpreted with caution.

Detection of regional blood perfusion changes in epileptic seizures with dynamic brain perfusion CT--a pilot study

BACKGROUND AND PURPOSE: Perfusion CT (P-CT) is used for acute stroke management, not, however, for evaluating epilepsy. To test the hypothesis that P-CT may identify patients with increased regional cerebral blood flow during subtle status epilepticus (SSE), we compared P-CT in SSE to different postictal conditions. METHODS: Fifteen patients (mean age 47 years, range 21-74) underwent P-CT immediately after evaluation in our emergency room. Asymmetry indices between affected and unaffected hemispheres were calculated for regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and mean transit time (MTT). Regional perfusion changes were compared to EEG findings. RESULTS: Three patients in subtle status epilepticus (group 1) had increased regional perfusion with electro-clinical correlate. Six patients showed postictal slowing on EEG corresponding to an area of regional hypoperfusion (group 2). CT and EEG were normal in six patients with a first epileptic seizure (group 3). Cluster analysis of asymmetry indices separated SSE from the other two groups in all three parameters, while rCBF helped to distinguish between chronic focal epilepsies and single events. CONCLUSION: Preliminary results indicate that P-CT may help to identify patients with SSE during emergency workup. This technique provides important information to neurologists or emergency physicians in the difficult clinical differential diagnosis of altered mental status due to subtle status epilepticus.

Dynamic changes of cardiac conduction during rapid pacing

Slow conduction and unidirectional conduction block (UCB) are key mechanisms of reentry. Following abrupt changes in heart rate, dynamic changes of conduction velocity (CV) and structurally determined UCB may critically influence arrhythmogenesis. Using patterned cultures of neonatal rat ventricular myocytes grown on microelectrode arrays, we investigated the dynamics of CV in linear strands and the behavior of UCB in tissue expansions following an abrupt decrease in pacing cycle length (CL). Ionic mechanisms underlying rate-dependent conduction changes were investigated using the Pandit-Clark-Giles-Demir model. In linear strands, CV gradually decreased upon a reduction of CL from 500 ms to 230-300 ms. In contrast, at very short CLs (110-220 ms), CV first decreased before increasing again. The simulations suggested that the initial conduction slowing resulted from gradually increasing action potential duration (APD), decreasing diastolic intervals, and increasing postrepolarization refractoriness, which impaired Na(+) current (I(Na)) recovery. Only at very short CLs did APD subsequently shorten again due to increasing Na(+)/K(+) pump current secondary to intracellular Na(+) accumulation, which caused recovery of CV. Across tissue expansions, the degree of UCB gradually increased at CLs of 250-390 ms, whereas at CLs of 180-240 ms, it first increased and subsequently decreased. In the simulations, reduction of inward currents caused by increasing intracellular Na(+) and Ca(2+) concentrations contributed to UCB progression, which was reversed by increasing Na(+)/K(+) pump activity. In conclusion, CV and UCB follow intricate dynamics upon an abrupt decrease in CL that are determined by the interplay among I(Na) recovery, postrepolarization refractoriness, APD changes, ion accumulation, and Na(+)/K(+) pump function.

Modifying peripheral IV catheters with side holes and side slits results in favorable changes in fluid dynamic properties during the injection of iodinated contrast material

OBJECTIVE: The purpose of this study was to compare a standard peripheral end-hole angiocatheter with those modified with side holes or side slits using experimental optical techniques to qualitatively compare the contrast material exit jets and using numeric techniques to provide flow visualization and quantitative comparisons. MATERIALS AND METHODS: A Schlieren imaging system was used to visualize the angiocatheter exit jet fluid dynamics at two different flow rates. Catheters were modified by drilling through-and-through side holes or by cutting slits into the catheters. A commercial computational fluid dynamics package was used to calculate numeric results for various vessel diameters and catheter orientations. RESULTS: Experimental images showed that modifying standard peripheral IV angiocatheters with side holes or side slits qualitatively changed the overall flow field and caused the exiting jet to become less well defined. Numeric calculations showed that the addition of side holes or slits resulted in a 9-30% reduction of the velocity of contrast material exiting the end hole of the angiocatheter. With the catheter tip directed obliquely to the wall, the maximum wall shear stress was always highest for the unmodified catheter and was always lowest for the four-side-slit catheter. CONCLUSION: Modified angiocatheters may have the potential to reduce extravasation events in patients by reducing vessel wall shear stress.