Modification of Branched Polyethyleneimine Using Mesquite Gum for Its Improved Hemocompatibility

In the present study, the modification of branched polyethyleneimine (b-PEI) was carried out using mesquite gum (MG) to improve its hemocompatibility to be used in biomedical applications. In the copolymer synthesis process (carboxymethylated mesquite gum grafted polyethyleneimine copolymer (CBX-MG-PEI), an MG carboxymethylation reaction was initially carried out (carboxymethylated mesquite gum (CBX-MG). Subsequently, the functionalization between CBX-MG and b-PEI was carried out using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as crosslinking agents. The synthesis products were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Thermogravimetric analysis showed that CBX-MG and CBX-MG-PEI presented a lower decomposition temperature than MG. The CBX-MG-PEI has a high buffer capacity in the pH range of 4 to 7, similar to the b-PEI. In addition, the CBX-MG-PEI showed an improvement in hemocompatibility in comparison with the b-PEI. The results showed a non-hemolytic property at doses lower than 0.1 µg/mL (CBX-MG-PEI). These results allow us to propose that this copolymer be used in transfection, polymeric nanoparticles, and biomaterials due to its physicochemical and hemocompatibility properties.

Chemical composition, aerobic stability, and fermentation pattern of white oat silage wilted with glyphosate

White oat has good nutritional quality but is not an easy forage to ensile due to its high buffer capacity and moisture content at ensiling moment. Therefore, wilting is necessary to offset such negative aspects. However, this process demands skilled workforce and adequate machinery. In this way, chemical desiccation is a promising technology to reduce the steps needed for wilting. Thus, we aimed to evaluate the effects of glyphosate as a chemical desiccant on the nutritional quality, fermentation pattern, losses, and aerobic stability of wilted white oat (Avena sativa) silages. White oat sowing occurred in the first fortnight of May 2013. Desiccant application took place when oat reached milky-dough grain stage (96 days after planting). Glyphosate doses evaluated were 0, 500, 750, 1000, and 1250 mL ha?1. Three days after desiccation, all treatments were ensiled, and the silos were stored for 150 days. A completely randomized design was used, and all statistical procedures were performed by means of Bayesian Inference. No differences were found for lactic acid, but treated-silage pH linearly decreased. The lowest concentration of butyric acid (3.40 mg kg-1) was observed at 900.80 mL ha-1. For ammonia, the highest point (50 g kg-1) occurred at 916.51 mL ha-1. Aerobic stability was not influenced by treatments. Maximum dry matter recovery index (934 g kg-1) was observed at 864.20 mL ha-1 glyphosate. Wilted forage from treatments 500 mL ha-1, 750 mL ha-1, and 1000 mL ha-1 had greater dry matter content compared to control (320.1, 326, 301.3, and 270.7 g kg-1 respectively). Hemicellulose linearly decreased and crude protein linearly increased. The lowest concentrations of neutral detergent fiber (642.8 g kg-1) and neutral-detergent insoluble nitrogen (2.30 g kg-1) occurred at doses of 1141.32 mL ha-1 and 829.14 mL ha-1, respectively. In brief, for wilted white oat silage production, harvested at milky-dough grain stage, glyphosate application prior to ensiling up to 1000 mL ha-1 led to better conservation compared to non-treated silage.

Accuracy of methods to estimate potential acidity and lime requirement in soils of west region of Santa Catarina

ABSTRACT: The objective of this study was to compare two methods of evaluation of potencial acidity (H+Al) and two methods to estimate liming requirement (LR) for soils from the west region of Santa Catarina State, Brazil. Fourteen soils were incubated with 7 lime rates for 120 days, obtaining the real values of H+Al at pH 7.0 and LR. These values were used as reference to evaluate the accuracy of two H+Al estimating methods: SMP buffer and calcium acetate at pH 7.0, and to evaluate the accuracy of two LR methods: base saturation (BS) and SMP index. On average, H+Al was underestimated in 6 and 40% by SMP and calcium acetate methods, respectively, especially in soils with high buffer capacity. The LR was underestimated in 20 and 30% by SMP index and BS, respectively. The SMP Index showed a better LR estimative than BS, especially in soils with high buffer capacity.

The Nutrition of Buffalo Milk: A Comparison with Cow Milk

Milk is the essential source of nutrition for young mammals before they are able to digest other types of food. To explore the complex nutritive value of buffalo milk, the general composition, buffer capacity, the properties of buffalo yogurt were analyzed, meanwhile, cow milk as a control group was also studied. The results show that the nutritional value of buffalo milk is higher than that of cow milk, exhibiting the high protein, fat, lactose, total solids and nonfat solids contents, and the high buffer capacity. Yogurt with the probiotics characterized by acidification activity, syneresis and water-holding capacity, has the functional of lactobacillus resisting lactose intolerance and reducing constipation. Buffalo yogurt shows the higher stability and nutritional value.

Effect of fumaric acid supplementation and dietary buffering capacity on the concentration of microbial metabolites in ileal digesta of young pigs

Experiments were conducted to determine the effect of different levels of fumaric acid supplementation to diets with a low or high buffer capacity on the concentrations of microbial metabolites and lipopolysaccharides, as an indicator of gram negative bacteria in ileal digesta of young pigs. In two experiments, 12 pigs each were weaned at 14 d of age and fitted with a simple T-cannula at the distal ileum between 15 and 17 d of age. In experiment 1, the pigs were fed wheat–soybean meal diets without or with inclusion of 1, 2 or 3% fumaric acid according to a balanced two-period changeover design. In experiment 2, the same diets were fed, except that the dietary buffering capacity was increased by inclusion of 3% sodium bicarbonate to all diets. The pigs were fed three times daily, equal amounts at 8 h intervals. The diets were supplied at a rate of 5% (wt/wt) of body weight. The inclusion of fumaric acid to the diet with a low buffering capacity (exp. 1) decreased (P < 0.05) the concentrations of lactic acid, ammonia, spermidine and lipopolysaccharides in ileal digesta. Supplementation of fumaric acid to a diet with a high buffering capacity (exp. 2) did not affect (P > 0.05) the concentrations of fermentation products in ileal digesta, but there was a decrease (P < 0.05) in the concentration of lipopolysaccharides. Furthermore, in both experiments, the concentration of most fermentation products decreased (P < 0.05) with increasing age after weaning. These results give further evidence that supplementation of fumaric acid to diets for young pigs during the first 3–4 wk after weaning reduces the metabolic activity and the concentrations of bacteria in the gastrointestinal tract. The magnitude of this effect, however, is dependent on the buffering capacity and the inclusion level of fumaric acid in the diets. Key words: Pigs, fumaric acid, buffering capacity, microbial metabolites, ileal digesta, lipopolysaccharides

Analysis of the effects of hematocrit on pulmonary CO2 transfer

A mathematical model of the chemical and transport events in blood during and after gas exchange has been used to examine the rates of CO2 excretion (Vco2) and O2 uptake (Vo2) in the lung at different levels of hematocrit (Hct), assuming fixed mixed venous blood O2 and CO2 contents and alveolar gases and constant cardiac output. The results show that a reduction in Hct from 45 to 30% leads to approximately 25% reduction in Vco2 compared with approximately 30% reduction in Vo2. Reduction of Hct from 45 to 15% results in approximately 50% reduction in Vco2 and approximately 63% reduction in Vo2. An increase in Hct from 45 to 60% results in approximately 25% increase in Vco2, accompanied by approximately 30% increase in Vo2. These fractional changes in gas exchange are only slightly affected by the extent of catalysis of the plasma CO2-H2CO3 hydration-dehydration reactions in the pulmonary vasculature. The reduction in Vco2 with reductions in Hct are due to 1) decrease in the total quantity of Bohr protons released during diminution of Vo2, 2) decrease in the size of the high buffer capacity intraerythrocytic pool, and 3) decrease in the total surface area available for HCO-3/Cl- exchange across the red cell membrane. We conclude that hitherto unrecognized changes in Vco2 (in addition to the well-known changes in Vo2) may occur as a consequence of alterations in Hct.