A potential model for sodium chloride solutions based on the TIP4P/2005 water model.

Despite considerable efforts over more than two decades, our knowledge of the interactions in electrolyte solutions is not yet satisfactory. Not even one of the most simple and important aqueous solutions, NaCl(aq), escapes this assertion. A requisite for the development of a force field for any water solution is the availability of a good model for water. Despite the fact that TIP4P/2005 seems to fulfill the requirement, little work has been devoted to build a force field based on TIP4P/2005. In this work, we try to fill this gap for NaCl(aq). After unsuccessful attempts to produce accurate predictions for a wide range of properties using unity ionic charges, we decided to follow recent suggestions indicating that the charges should be scaled in the ionic solution. In this way, we have been able to develop a satisfactory non-polarizable force field for NaCl(aq). We evaluate a number of thermodynamic properties of the solution (equation of state, maximum in density, enthalpies of solution, activity coefficients, radial distribution functions, solubility, surface tension, diffusion coefficients, and viscosity). Overall the results for the solution are very good. An important achievement of our model is that it also accounts for the dynamical properties of the solution, a test for which the force fields so far proposed failed. The same is true for the solubility and for the maximum in density where the model describes the experimental results almost quantitatively. The price to pay is that the model is not so good at describing NaCl in the solid phase, although the results for several properties (density and melting temperature) are still acceptable. We conclude that the scaling of the charges improves the overall description of NaCl aqueous solutions when the polarization is not included.

Flour from Prosopis alba cotyledons: A natural source of nutrient and bioactive phytochemicals.

The Prosopis alba seed is a waste material in the process to produce pod flour. To suggest a potential use of these seeds it is necessary to determine the nutritional, phytochemical and functional quality of cotyledon flour from Prosopis alba. This flour showed high level of proteins (62%), low content of total carbohydrate and fat. Free polyphenol (1150±20mg GAE/100g flour) and carotenoids (10.55±0.05mg ß-CE/100g flour) compounds were the dominant compounds. The main identified constituents in the polyphenolic extracts were C- glycosyl flavones, including schaftoside, isoschaftoside, vicenin II, vitexin and isovitexin. The extract enriched in polyphenolic compounds exhibited ABTS(+) reducing capacity and scavenging activity of H2O2; and was able to inhibit phospholipase, lipoxygenase and cyclooxygenase, three pro-inflammatory enzymes. According to our results, the P. alba cotyledon flour could be considered as a new alternative in the formulation of functional foods or food supplements.

Evaluation of different bovine muscles to be applied in freeze-drying for instant meal. Study of physicochemical and senescence parameters.

The aim of the present research was to evaluate bovine muscles to be subjected to freeze-drying for an instant meal. Physicochemical and senescence parameters were evaluated. The experimental part was divided into two steps. In the first step, the Semitendinosus muscle was chosen to establish methodology and experimental conditions. Physicochemical, microstructure and senescence parameters were analysed. In the second step, economic bovine muscles such as Semimembranous and Spinalis dorsi were subjected to the same methodology and conditions as in the first step in order to compare them by analysing the same parameters. L* and a* values were statistically significant (P<0.05) for Semimembranous and Spinalis dorsi muscles, showing differences among condition effects and in muscles. Humidity and water activity showed among the muscles analysed that cooked and rehydrated samples did not exhibit differences. Microstructure of Semitendinosus and Semimembranous were not separated and fragmented as occurred with Spinalis dorsi after freeze-drying. Results allowed us to select among the muscles studied that Semimembranous was suitable and economic to be used in an instant meal.

[Etiology of community acquired pneumonia in inpatients children. Uruguay 1998-2004]. / Etiología de la neumonía bacteriana adquirida en la comunidad en niños hospitalizados. Uruguay 1998-2004.

Community acquired bacterial pneumonia represents 8.7% of overall discharges of children under 15 years old in the Pediatric Hospital of the Centro Hospitalario Pereira Rossell; since 1997 treatment guidelines are being applied. Changes in etiology of this disease in children hospitalized in our institution from 1998 to 2004 were studied. Streptococcus pneumoniae was the most frequent agent in every year of the period, 91.4 +/- 2.3%; its susceptibility to penicillin has remained stable; serotypes 14, 1 and 5 were the most frequent isolated. In 2002 the first case of community acquired methicillin resistant S. aureus was identified; isolations of this microorganism were 5.8% in 2003 and 6.3% in 2004. Surveillance of etiology of community acquired pneumonia is mandatory in order to adjust guidelines to changes in agents and their antimicrobial susceptibility.

Etiología de la neumonía bacteriana adquirida en la comunidad en niños hospitalizados: Uruguay 1998-2004 / Etiology of community acquired pneumonia in inpatients children: Uruguay 1998-2004

La neumonía bacteriana adquirida en la comunidad representa en promedio 8,7 por ciento de los egresos de niños bajo 15 años de edad asistidos en el Hospital Pediátrico del Centro Hospitalario Pereira Rossell; desde 1997 se aplican guías para su diagnóstico y tratamiento. Se estudió la evolución de la etiología de esta enfermedad en los niños hospitalizados en dicho hospital en el período 1998-2004. Streptococcus pneumoniae fue el agente más frecuente todos los años, 91,4 ± 2,3 por ciento. Su susceptibilidad a penicilina permaneció sin cambios; los serotipos más frecuentes fueron: 14, 1 y 5. En el año 2002 se identificó el primer caso de Staphylococcus aureus resistente a meticilina adquirido en comunidad; este agente representó 5,8 por ciento de los aislados en 2003 y 6,3 por ciento en 2004. Es necesario mantener la vigilancia de la etiología de la neumonía bacteriana adquirida en la comunidad para adecuar las guías de diagnóstico y tratamiento a los cambios en los agentes y su susceptibilidad a los antimicrobianos.

Community acquired bacterial pneumonia represents 8.7 percent of overall discharges of children under 15 years old in the Pediatric Hospital of the Centro Hospitalario Pereira Rossell; since 1997 treatment guidelines are being applied. Changes in etiology of this disease in children hospitalized in our institution from 1998 to 2004 were studied. Streptococcus pneumoniae was the most frequent agent in every year of the period, 91.4 ± 2.3 percent; its susceptibility to penicillin has remained stable; serotypes 14, 1 and 5 were the most frequent isolated. In 2002 the first case of community acquired methicillin resistant S. aureus was identified; isolations of this microorganism were 5.8 percent in 2003 and 6.3 percent in 2004. Surveillance of etiology of community acquired pneumonia is mandatory in order to adjust guidelines to changes in agents and their antimicrobial susceptibility.

Calibration of sap flow estimated by the compensation heat pulse method in olive, plum and orange trees: relationships with xylem anatomy.

The compensation heat pulse method is widely used to estimate sap flow in conducting organs of woody plants. Being an invasive technique, calibration is crucial to derive correction factors for accurately estimating the sap flow value from the measured heat pulse velocity. We compared the results of excision and perfusion calibration experiments made with mature olive (Olea europaea L. 'Manzanilla de Sevilla'), plum (Prunus domestica L. 'Songal') and orange (Citrus sinensis (L.) Osbeck. 'Cadenero') trees. The calibration experiments were designed according to current knowledge on the application of the technique and the analysis of measured heat pulse velocities. Data on xylem characteristics were obtained from the experimental trees and related to the results of the calibration experiments. The most accurate sap flow values were obtained by assuming a wound width of 2.0 mm for olive and 2.4 mm for plum and orange. Although the three possible methods of integrating the sap velocity profiles produced similar results for all three species, the best results were obtained by calculating sap flow as the weighted sum of the product of sap velocity and the associated sapwood area across the four sensors of the heat-pulse-velocity probes. Anatomical observations showed that the xylem of the studied species can be considered thermally homogeneous. Vessel lumen diameter in orange trees was about twice that in the olive and plum, but vessel density was less than half. Total vessel lumen area per transverse section of xylem tissue was greater in plum than in the other species. These and other anatomical and hydraulic differences may account for the different calibration results obtained for each species.

Role of neuronal nitric oxide synthase in response to hypertonic saline loading in rats.

AIMS: This study analyses the influence of neuronal nitric oxide synthase (nNOS) blockade with 7-nitroindazole (7NI) on the haemodynamic and renal response to a hypertonic saline load (HSL). We also evaluated the effects of non-specific NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME). METHODS: The following groups were used: controls, rats treated with 7NI at 0.5 or 5 mg kg(-1), and rats treated with L-NAME at 0.5 or 5 mg kg(-1). A further five groups received an isotonic saline load (ISL). RESULTS: Mean arterial pressure (MAP) was significantly increased in control rats after HSL. MAP was further increased in both 7NI-treated groups, and the L-NAME groups showed marked dose-related pressor responses. During ISL, MAP was only significantly increased in the group treated with 5 mg kg(-1) of L-NAME. The pressure-natriuresis relationship during the experimental period after the HSL was reduced in the 7NI group treated with 5 mg kg(-1) and severely attenuated in both L-NAME groups. The increase in plasma sodium was significantly greater after the HSL in both 7NI groups and both L-NAME groups compared with controls. CONCLUSIONS: The present results suggest that nNOS and other NOS isozymes play a counter-regulatory role in the pressor response to HSL. Moreover, the blockade of nNOS with the higher dose of 7NI produces a blunted pressure-natriuresis relationship in response to the HSL. Finally, it is concluded that nNOS participates in the homeostatic cardiovascular and renal response to hypertonic saline loading by attenuating the blood pressure increase and hypernatremia, and facilitating natriuresis.

Effects of deoxycorticosterone on renal vascular reactivity and flow-pressure curve in spontaneously hypertensive rats.

The role of mineralocorticoids as sodium retaining hormones has been recently enlarged to include their function as modulators of cardiovascular function and injury. This study evaluated the contribution of possible functional changes in resistance vessels to the additional BP increase produced by the chronic administration of DOCA to SHR. The flow-pressure curve and renal responses to vasoconstrictors (phenylephrine [Phe] and angiotensin II [AII]) and vasodilators (acetylcholine [ACh] and nitroprusside [NP]) were characterized in isolated kidneys from Wistar Kyoto (WKY) and SHR treated or untreated with DOCA for nine weeks. DOCA increased BP in SHR but did not modify BP in WKY rats. Kidneys from SHR showed enhanced reactivity to Phe and AII that was not increased by DOCA. DOCA reduced sensitivity to AII in SHR. Responsiveness to ACh was increased in SHR and was not attenuated by DOCA in WKY or SHR. Vasodilator response to NP was not significantly affected by DOCA in WKY or SHR. The flow-pressure curve was markedly up-shifted in SHR when compared with kidneys from WKY rats. DOCA administration did not modify the flow-pressure curve in WKY but produced attenuation at low flow levels in SHR. Our results demonstrate that DOCA increases BP in SHR but does not increase the flow-pressure curve or renal vascular reactivity to vasoconstrictors, and does not reduce responsiveness to endothelium-dependent and independent vasodilators in SHR or WKY rats. Therefore, our data suggest that the BP increase produced by DOCA in SHR is not related to abnormalities in vascular function in resistance vessels.