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Search Results: 1 - 10 of 6359 matches for " Horacio Santiago;Kiefer "
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Níveis de fósforo digestível para suínos em fase de crescimento
Bünzen, Silvano;Rostagno, Horacio Santiago;Kiefer, Charles;Teixeira, Alexandre de Oliveira;Ribeiro Junior, Valdir;
Revista Brasileira de Zootecnia , 2012, DOI: 10.1590/S1516-35982012000200013
Abstract: this study was carried out to determine the digestible phosphorus requirement for growing swine. seventy crossbred swine (35 castrated males and 35 females), with initial weight of 29.72±1.52 kg were distributed in a completely randomized design with five treatments, seven replicates and two animals (one male and one female) per experimental unit. the experiment lasted 21 days. the treatments were composed of diets formulated with corn and soybean meal, supplemented with dicalcium phosphate, corresponding to five levels of digestible phosphorus (0.19; 0.25; 0.30; 0.35 and 0.40%). for each phosphorus level, limestone was added to maintain the calcium:phosphorus ratio constant. the increase in digestible phosphorus influenced feed intake and weigh gain quadratically, and the maximum values for those parameters were obtained with the levels of 0.32 and 0.31% digestible phosphorus, respectively. there was no effect of digestible phosphorus levels on the feed:gain ratio. the ashes and calcium contents analyzed in the metatarsi were not influenced by digestible phosphorus levels, while the phosphorus content in bone showed linear response. the requirement of digestible phosphorus for pigs fed diets based on corn and soybean meal is 0.31%, corresponding to a daily intake of 5.87 g digestible phosphorus.
Simultaneous Echo Refocused Magnetization Transfer Imaging  [PDF]
Claus Kiefer
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.43021
Abstract: Purpose: To increase the efficiency of densely encoded magnetization transfer imaging of the brain, we time-multiplex multiple slices within the same readout using simultaneous echo refocusing FLASH imaging with magnetization transfer (MT) preparation (MT-SER-FLASH). Materials and Methods: Inefficiency in total scan time results from the number of frequency samples needed for sufficient quality of quantitative parameter maps for a binary spin bath model. We present a highly efficient multiplexing method, simultaneous echo refocused magnetization transfer imaging (MT-SER-FLASH) for reducing the total scan time of MT imaging by one-third. The specific absorption rate (SAR) was also reduced by reducing the number of MT-pulses per volume. Results: 2D-MT-SER-FLASH is performed in 19 minutes rather than 1 hour, acceptable for routine clinical application. The SAR could be reduced to 69% instead of more than 100% with a standard 2D or 3D-FLASH with MT-preparation. Conclusion: The net reduction of scan time and SAR enables the use of quantitative model based magnetization transfer imaging within a clinical environment.
Modelling Magnetization Transfer Considering Spin-Locking Effects  [PDF]
Claus Kiefer
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.44027
Abstract: Purpose: Recently it was demonstrated that spin-locking (SL) effects can manifest as pseudo magnetization transfer (MT). To our best knowledge the MT models proposed so far cannot distinguish between saturation effects caused by the MT preparation pulses and SL phenomena. Therefore a new MT model is proposed. Materials and Methods: A binary spin-bath model for magnetization transfer was extended in that sense that SL effects are considered. The new modified spin bath model was tested for a phantom with different agar concentrates (2%, 4%, 8%) and a MnCl2 (0.3 mM) solution. Results: The mean fitting error is 3.2 times lower for the modified model compared to the original model. Especially the parameter F for the fractional part of the bounded proton pool describes the situation for the MnCl2 (F = 0) better than the original model (F = 0.004). Conclusion: The proposed mathematical modifications of the binary spin-bath model considering SL seem to be a step in the right direction in that sense that the effects associated with SL are not interpreted as magnetization transfer.
Agglutinating Activity and Structural Characterization of Scalarin, the Major Egg Protein of the Snail Pomacea scalaris (d’Orbigny, 1832)
Santiago Ituarte, Marcos Sebastián Dreon, Marcelo Ceolin, Horacio Heras
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050115
Abstract: Apple snail perivitellins are emerging as ecologically important reproductive proteins. To elucidate if the protective functions of the egg proteins of Pomacea canaliculata (Caenogastropoda, Ampullariidae), involved in embryo defenses, are present in other Pomacea species we studied scalarin (PsSC), the major perivitellin of Pomacea scalaris. Using small angle X-ray scattering, fluorescence and absorption spectroscopy and biochemical methods, we analyzed PsSC structural stability, agglutinating activity, sugar specificity and protease resistance. PsSC aggluttinated rabbit, and, to a lesser extent, human B and A erythrocytes independently of divalent metals Ca2+ and Mg2+ were strongly inhibited by galactosamine and glucosamine. The protein was structurally stable between pH 2.0 to 10.0, though agglutination occurred only between pH 4.0 to 8.0 (maximum activity at pH 7.0). The agglutinating activity was conserved up to 60°C and completely lost above 80°C, in agreement with the structural thermal stability of the protein (up to 60°C). PsSC was able to withstand in vitro gastrointestinal digestion, and showed no trypsin inhibition activity. The presence of lectin activity has been reported in eggs of other Pomacea snails, but here we link for the first time, this activity to an apple snail multifunctional perivitellin. This novel role for a snail egg storage protein is different from closely related P.canaliculata defensive proteins.
The Role of the Proteinase Inhibitor Ovorubin in Apple Snail Eggs Resembles Plant Embryo Defense against Predation
Marcos Sebastián Dreon,Santiago Ituarte,Horacio Heras
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015059
Abstract: Fieldwork has thoroughly established that most eggs are intensely predated. Among the few exceptions are the aerial egg clutches from the aquatic snail Pomacea canaliculata which have virtually no predators. Its defenses are advertised by the pigmented ovorubin perivitellin providing a conspicuous reddish coloration. The nature of the defense however, was not clear, except for a screening for defenses that identified a neurotoxic perivitellin with lethal effect on rodents.
Lobulectomía pulmonar toracoscópica: resultados iniciales en pediatría
Martínez Ferro,Marcelo; Vidaurreta,Santiago; Buela,Enrique; Bignon,Horacio;
Archivos argentinos de pediatr?-a , 2010,
Abstract: the objective of the present study consists of revising our initial experience with the use of thoracoscopic surgery for lung resections and their complications. clinical histories and videos, from patients treated surgically at the fundación hospitalaria-private children hospital and cemic universitary hospital from april 2005 to october 2008, were retrospectivelly estudied. eleven female and 9 male patients were included. the median surgical time was 150 min (range: 60-270 min). the median time of chest tube permanence was 3 days (range: 2-10 days). median hospital stay was 15 days (range: 3-29 days). it was concluded that thoracoscopic lung lobectomies are technically feasible and applicable to all paediatric ages; they should be considered as an alternative approach for trained groups.
Hydrokinetic Assessment of the Kvichak River near Igiugig, Alaska, Using a Two-Dimensional Hydrodynamic Model  [PDF]
Horacio Toniolo
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.46056
Abstract: Two-dimensional hydrodynamic simulations were performed on a monthly basis along 2.5 km of the Kvichak River near Igiugig in southwest Alaska, USA, to estimate flow conditions and to assess the hydrokinetic potential of the river reach. Instantaneous power density function along the computational domain was calculated. Study results indicate that two areas may be suitable for deploying turbines. The best option is located near the town, where the channel is relatively straight. A second possible site is located near the end of the study reach (approximately 2.3 km, along the river, from Lake Illiamna). Monthly-averaged velocities along the thalweg ranged from 1.7 to 2.7 m/s; and from 1.1 to 2 m/s at the upstream and downstream sites, respectively. Similarly, averaged values for the instantaneous power density, reduced by an extraction coefficient, were approximately 1500 and 5500 W/m2 during April and September, respectively, at the upstream site, as well as 400 and 2500 W/m2 for the same months at the downstream site. It was found that a previous resource assessment, which considered cross-sectionally averaged velocities, substantially underestimated the available power density along the river reach. Finally, the importance of having adequate bathymetric data is demonstrated by comparing field measurements with model simulations.
Bed Forms and Sediment Characteristics along the Thalweg on the Tanana River near Nenana, Alaska, USA  [PDF]
Horacio Toniolo
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.41003
Abstract:

Sediment sampling and longitudinal river-bottom surveys were conducted along the thalweg on the Tanana River near the city of Nenana, Alaska, USA, to provide basic information for the engineering design requirements of hydrokinetic devices to be deployed in the area. The study reach was located at approximately 64°33'50\"N and 149°04'W. The Tanana is a large glacier-fed river, with open-water flow conditions from May to October. The river presents a single channel in the study area. Granulometric analyses of sediment moving near the riverbed reveals the coexistence of three distinctive types of sediment along the study reach: 1) nearly uniform fine sand; 2) bimodal distributions containing fine sand and medium gravel; and 3) medium gravel. Preliminary relationships between sediment loads and discharge were developed. Dunes with small superimposed dunes were found along the reach. The basic geometric parameters (i.e., wavelength and height) of dunes were measured, and steepness was calculated. In general, dune wavelength increased with increasing discharge. Dune wavelengths ranged from 41 to 67 m, while small-dune wavelengths ranged from 13 to 16 m. Steepness increased slightly with increasing discharge.

 

cGMP-Phosphodiesterase Inhibition Enhances Photic Responses and Synchronization of the Biological Circadian Clock in Rodents
Santiago A. Plano, Patricia V. Agostino, Horacio O. de la Iglesia, Diego A. Golombek
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037121
Abstract: The master circadian clock in mammals is located in the hypothalamic suprachiasmatic nuclei (SCN) and is synchronized by several environmental stimuli, mainly the light-dark (LD) cycle. Light pulses in the late subjective night induce phase advances in locomotor circadian rhythms and the expression of clock genes (such as Per1-2). The mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase (GC), cGMP and its related protein kinase (PKG). Pharmacological manipulation of cGMP by phosphodiesterase (PDE) inhibition (e.g., sildenafil) increases low-intensity light-induced circadian responses, which could reflect the ability of the cGMP-dependent pathway to directly affect the photic sensitivity of the master circadian clock within the SCN. Indeed, sildenafil is also able to increase the phase-shifting effect of saturating (1200 lux) light pulses leading to phase advances of about 9 hours, as well as in C57 a mouse strain that shows reduced phase advances. In addition, sildenafil was effective in both male and female hamsters, as well as after oral administration. Other PDE inhibitors (such as vardenafil and tadalafil) also increased light-induced phase advances of locomotor activity rhythms and accelerated reentrainment after a phase advance in the LD cycle. Pharmacological inhibition of the main downstream target of cGMP, PKG, blocked light-induced expression of Per1. Our results indicate that the cGMP-dependent pathway can directly modulate the light-induced expression of clock-genes within the SCN and the magnitude of light-induced phase advances of overt rhythms, and provide promising tools to design treatments for human circadian disruptions.
Changes in body composition in lactating adolescent mothers
González,Horacio F; Malpeli,Agustina; Mansur,José L; De Santiago,Soledad; Etchegoyen,Graciela S;
Archivos Latinoamericanos de Nutrición , 2005,
Abstract: we assessed changes in body composition in lactating adolescent mothers living under unfavorable socioeconomic and sanitary conditions. a total of 17 healthy primiparous adolescents under 17 years of age attending the maternity hospital of the city of la plata, argentina, were followed at 4 time points (15 days and 3, 6 and 12 months postpartum) to assess, a) dietary intake, b) practice of physical activity, c) nutritional condition (weight, height, body mass index; bmi; according to age, and body composition by the sum of skinfold measurements), d) characteristics of lactation, and e) growth parameters of the child. the mean age of adolescents was 15.06 ± 0.66 years (mean menarchal age, 11.59 ± 0.80 years). all adolescents breastfed up to 12 months postpartum, and maternal milk covered above 80% the baby intake (mean 7.06 ± 2.54 breast feeds/day). while the daily intake of nutrients by adolescent mothers was constant up to 6 months postpartum, there was a modest decrease in that of proteins, carbohydrates and lipids 15 days and 12 months postpartum. the decrease in energetic intake during the same period was significant (p< 0.05). the practice of physical activity was classified as moderate during the follow-up period. whereas mean basal percent of fat body mass (fbm) was 29.85 ± 2.87, and decreased significantly at 6 (27.2% ± 3.9%; p= 0.02) and 12 (26.1% ± 3.9%; p=0.002) months postpartum, changes in lean body mass (lbm) were not significant. in conclusion, lactating adolescents maintained lbm, whereas weight, fbm and bmi decreased markedly from 3 months postpartum.
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