Effects of dietary urea levels on milk protein fractions of Holstein cows

The aim of this study was to evaluate the effects of substituting soybean meal for urea on milk protein fractions (casein, whey protein and non-protein nitrogen) of dairy cows in three dietary levels. Nine mid-lactation Holstein cows were used in a 3 x 3 Latin square arrangement, composed of 3 treatments, 3 periods of 21 days each, and 3 squares. The treatments consisted of three different diets fed to lactating cows, which were randomly assigned to three groups of three animals: (A) no urea inclusion, providing 100% of crude protein (CP), rumen undegradable protein (RUP) and rumen degradable protein (RDP) requirements, using soybean meal and sugarcane as roughage; (B) urea inclusion at 7.5 g/kg DM in partial substitution of soybean meal CP equivalent; (C) urea inclusion at 15 g/kg DM in partial substitution of soybean meal CP equivalent. Rations were isoenergetic and isonitrogenous-1 60 g/kg DM of crude protein and 6.40 MJ/kg DM of net energy for lactation. When the data were analyzed by simple polynomial regression, no differences were observed among treatments in relation to milk CP content, true protein, casein, whey protein, non-casein and non-protein nitrogen, or urea. The milk true protein:crude protein and casein:true protein ratios were not influenced by substituting soybean meal for urea in the diet. Based on the results it can be concluded that the addition of urea up to 15 g/kg of diet dry matter in substitution of soybean meal did not alter milk protein concentration casein, whey protein and its non-protein fractions, when fed to lactating dairy cows. (c) 2007 Elsevier B.V. All rights reserved.

Effects of milk supplementation with skim milk powder, whey protein concentrate and sodium caseinate on acidification kinetics, rheological properties and structure of nonfat stirred yogurt

Milk supplementation with milk proteins in four different levels was used to investigate the effect on acidification and textural properties of yogurt. Commercial skim milk powder was diluted in distilled water, and the supplements were added to give different enriched-milk bases; these were heat treated at 90 degrees C for 5 min. These mixtures were incubated with the bacterial cultures for fermentation in a water bath, at 42 degrees C, until pH 4.50 was reached. Chemical changes during fermentation were followed by measuring the pH. Protein concentration measurements, microbial counts of Lactobacillus bulgaricus and Streptococcus thermophilus, and textural properties (G`, G ``, yield stress and firmness) were determined after 24 h of storage at 4 degrees C. Yogurt made with milk supplemented with sodium caseinate resulted in significant properties changes, which were decrease in fermentation time, and increase in yield stress, storage modulus, and firmness, with increases in supplement level. Microstructure also differed from that of yogurt produced with milk supplemented with skim milk powder or sodium caseinate. (C) 2009 Elsevier Ltd. All rights reserved.

Aluminum as an endocrine disruptor in female Nile tilapia (Oreochromis niloticus)

The effects of aluminum on plasma ion, lipid, protein and steroid hormone concentration were evaluated in Oreochromis niloticus broodstock females. Lipid and protein concentrations from the gonads and liver were also measured Experiments were performed at neutral and acidic water pH Four groups of fish were tested for 96 h. 1) control conditions at neutral water pH, 2) control conditions at acidic water pH (CTR-Ac). 3) aluminum at neutral water pH (Al-N), and 4) aluminum at acidic water pH (Al-Ac) Aluminum and acidic water pH exposure caused no ionoregulatory disturbances Total lipid concentration increased in the mature gonads and decreased in the liver, suggesting an acceleration of lipid mobilization to the ovaries in animals exposed to aluminum However, a decreased protein concentration in ovaries was also observed Exposure of control fish to acidic water pH caused an increased concentration of plasma 17 alpha-hydroxyprogesterone However, females exposed to aluminum at acidic water pH showed a decreased of plasma 17 alpha-hydroxyprogesterone and cortisol. No differences in plasma 17 beta-estradiol were observed The physiological mechanisms underlying the disturbances observed are discussed focusing on reproduction We suggest that aluminum can be considered an endocrine disrupting compound in mature O. mloticus females (C) 2010 Elsevier Inc. All rights reserved

Bradykinin inducible receptor is essential to lipopolysaccharide-induced acute lung injury in mice

Lipopolysaccharides from gram-negative bacteria are amongst the most common causative agents of acute lung injury, which is characterized by an inflammatory response, with cellular infiltration and the release of mediators/cytokines. There is evidence that bradykinin plays a role in lung inflammation in asthma but in other types of lung inflammation its role is less clear. In the present study we evaluated the role of the bradykinin B(1) receptor in acute lung injury caused by lipopolysaccharide inhalation and the mechanisms behind bradykinin actions participating in the inflammatory response. We found that in C57BI/6 mice, the bradykinin B(1) receptor expression was up-regulated 24 h after lipopolysaccharide inhalation. At this time, the number of cells and protein concentration were significantly increased in the bronchoalveolar lavage fluid and the mice developed airway hyperreactivity to methacholine. In addition, there was an increased expression of tumor necrosis factor-alpha, interleukin-1 beta and interferon-gamma and chemokines (monocytes chemotactic protein-1 and KC) in the bronchoalveolar lavage fluid and in the lung tissue. We then treated the mice with a bradykinin B, receptor antagonist, R-954 (Ac-Orn-[Oic(2), alpha-MePhe(5), D-beta Nal(7), Ile(8)]desArg(9)-bradykinin), 30 min after lipopolysaccharide administration. We observed that this treatment prevented the airway hyperreactivity as well as the increased cellular infiltration and protein content in the bronchoalveolar lavage fluid. Moreover, R-954 inhibited the expression of cytokines/chemokines. These results implicate bradykinin, acting through B(1) receptor, in the development of acute lung injury caused by lipopolysaccharide inhalation. (C) 2010 Elsevier B.V. All rights reserved.

Thermodynamic characterization of the palm tree Roystonea regia peroxidase stability

The structural stability of a peroxidase, a dimeric protein from royal palm tree (Roystonea regia) leaves, has been characterized by high-sensitivity differential scanning calorimetry, circular dichroism, steady-state tryptophan fluorescence and analytical ultracentifugation under different solvent conditions. It is shown that the thermal and chemical (using guanidine hydrochloride (Gdn-HCl)) folding/unfolding of royal palm tree peroxidase (RPTP) at pH 7 is a reversible process involving a highly cooperative transition between the folded dimer and unfolded monomers, with a free stabilization energy of about 23 kcal per mol of monomer at 25 degrees C. The structural stability of RPTP is pH-dependent. At pH 3, where ion pairs have disappeared due to protonation, the thermally induced denaturation of RPTP is irreversible and strongly dependent upon the scan rate, suggesting that this process is under kinetic control. Moreover, thermally induced transitions at this pH value are dependent on the protein concentration, allowing it to be concluded that in solution RPTP behaves as dimer, which undergoes thermal denaturation coupled with dissociation. Analysis of the kinetic parameters of RPTP denaturation at pH 3 was accomplished on the basis of the simple kinetic scheme N ->(k) D, where k is a first-order kinetic constant that changes with temperature, as given by the Arrhenius equation; N is the native state, and D is the denatured state, and thermodynamic information was obtained by extrapolation of the kinetic transition parameters to an infinite heating rate. Obtained in this way, the value of RPTP stability at 25 degrees C is ca. 8 kcal per mole of monomer lower than at pH 7. In all probability, this quantity reflects the contribution of ion pair interactions to the structural stability of RPTP. From a comparison of the stability of RPTP with other plant peroxidases it is proposed that one of the main factors responsible for the unusually high stability of RPTP which enhances its potential use for biotechnological purposes, is its dimerization. (c) 2008 Elsevier Masson SAS. All rights reserved.

The stability and aggregation properties of the GTPase domain from human SEPT4

The septins are a family of conserved proteins involved in cytokinesis and cortical organization. An increasing amount of data implicates different septins in diverse pathological conditions including neurodegenerative disorders, neoplasia and infections. Human SEPT4 is a member of this family and its tissue-specific ectopic expression profile in colorectal and urologic cancer makes it a useful diagnostic biomarker. Thermal unfolding of the GTPase domain of SEPT4 (SEPT4-G) revealed an unfolding intermediate which rapidly aggregates into amyloid-like fibers under physiological conditions. In this study, we examined the effects of protein concentration, pH and metals ions on the aggregation process of recombinant SEPT4-G using a series of biophysical techniques, which were also employed to study chemical unfolding and stability. Divalent metal ions caused significant acceleration to the rate of SEPT4-G aggregation. Urea induced unfolding was shown to proceed via the formation of a partially unfolded intermediate state which unfolds further at higher urea concentrations. The intermediate is a compact dimer which is unable to bind GTR At 1 M urea concentration, the intermediate state was plagued by irreversible aggregation at temperatures above 30 degrees C. However, higher urea concentration resulted in a marked decay of the aggregation, indicating that the partially folded structures may be necessary for the formation of these aggregates. The results presented here are consistent with the recently determined crystal structure of human septins and shed light on the aggregation properties of SEPT4 pertinent to its involvement in neurodegenerative disease. (C) 2008 Elsevier B.V. All rights reserved.

Novel immunoadjuvants based on cationic lipid: Preparation, characterization and activity in vivo

The interactions between three different protein antigens and dioctadecyldimethylammonium bromide (DODAB) dispersed in aqueous solutions from probe sonication or adsorbed its one bilayer onto particles was comparatively investigated. The three model proteins were bovine serum albumin (BSA), purified 18 kDa/14 kDa antigens from Taenia crassiceps (18/14-Tcra) and a recombinant, heat-shock protein hsp-18 kDa from Mycobacterium leprae. Protein-DODAB complexes in water solution were characterized by dynamic light scattering for sizing and zeta-potential analysis. Cationic complexes (80-100 nm of mean hydrodynamic diameter) displayed sizes similar to those of DODAB bilayer fragments (BF) in aqueous solution and good colloid stability over a range of DODAB and protein concentrations. The amount of cationic lipid required for attaining zero of zeta-potential at a given protein amount depended on protein nature being smaller for 18 kDa/14 kDa antigens than for BSA. Mean diameters for DODAB/protein complexes increased, whereas zeta-potentials decreased with NaCl or protein concentration. In mice, weak IgG production but significant cellular immune responses were induced by the complexes in comparison to antigens alone or carried by aluminum hydroxide as shown from IgG in serum determined by ELISA, delayed type hypersensitivity reaction from footpad swelling tests and cytokines analysis. The novel cationic adjuvant/protein complexes revealed good colloid stability and potential for vaccine design at a reduced DODAB concentration. (C) 2009 Elsevier Ltd. All rights reserved.

Sodium Tungstate on Some Biochemical Parameters of the Parotid Salivary Gland of Streptozotocin-Induced Diabetic Rats: A Short-Term Study

Several studies have shown the antidiabetic properties of sodium tungstate. In this study, we evaluated some biochemical parameters of the parotid salivary gland of streptozotocin-induced diabetic rats treated with sodium tungstate solution (2 mg/ml). The studied groups were: untreated control (UC), treated control (TC), untreated diabetic (UD), and treated diabetic (TD). After 2 and 6 weeks of treatment, parotid gland was removed and total protein and sialic acid (free and total) concentration and amylase and peroxidase activities were determined. Data were compared by variance analysis and Tukey test (p < 0.05). The sodium tungstate treatment modestly decreased the glycemia of streptozotocin-induced diabetic rats. At week 2 of the study, parotid gland of diabetic rats presented a reduction of total protein concentration (55%) and an increase of amylase (120%) and peroxidase (160%) activities, free (150%) and total (170%) sialic acid concentration. No alteration in the evaluated parameters at week 6 of the study was observed. Sodium tungstate presented no significant effect in parotid gland. Our results suggest that diabetes causes initial modification in biochemical composition of parotid. However, this gland showed a recovery capacity after 6 week of the experimental time. Sodium tungstate has no effect in peripheral tissues, such as salivary glands.

Optimization of the rheological properties of probiotic yoghurts supplemented with milk proteins

This study aimed to optimize the rheological properties of probiotic yoghurts supplemented with skimmed milk powder (SMP) whey protein concentrate (WPC) and sodium caseinate (Na-Cn) by using an experimental design type simplex-centroid for mixture modeling It Included seven batches/trials three were supplemented with each type of the dairy protein used three corresponding to the binary mixtures and one to the ternary one in order to increase protein concentration in 1 g 100 g(-1) of final product A control experiment was prepared without supplementing the milk base Processed milk bases were fermented at 42 C until pH 4 5 by using a starter culture blend that consisted of Streptococcus thermophilus Lactobacillus delbrueckii subsp bulgaricus and Bifidobacterium (Humans subsp lactis The kinetics of acidification was followed during the fermentation period as well the physico-chemical analyses enumeration of viable bacteria and theological characteristics of the yoghurts Models were adjusted to the results (kinetic responses counts of viable bacteria and theological parameters) through three regression models (linear quadratic and cubic special) applied to mixtures The results showed that the addition of milk proteins affected slightly acidification profile and counts of S thermophilus and B animal`s subsp lactis but it was significant for L delbrueckii subsp bulgaricus Partially-replacing SMP (45 g/100 g) with WPC or Na-Cn simultaneously enhanced the theological properties of probiotic yoghurts taking into account the kinetics of acidification and enumeration of viable bacteria (C) 2010 Elsevier Ltd All rights reserved

Thermal stability of extracellular hemoglobin of Glossoscolex paulistus: Determination of activation parameters by optical spectroscopic and differential scanning calorimetric studies

Glossoscolex paulistus hemoglobin (HbGp) was studied by dynamic light scattering (DLS), optical absorption spectroscopy (UV-VIS) and differential scanning calorimetry (DSC). At pH 7.0, cyanomet-HbGp is very stable, no oligomeric dissociation is observed, while denaturation occurs at 56 degrees C, 4 degrees C higher as compared to oxy-HbGp. The oligomeric dissociation of HbGp occurs simultaneously with some protein aggregation. Kinetic studies for oxy-HbGp using UV-VIS and DES allowed to obtain activation energy (E(a)) values of 278-262 kJ/mol (DES) and 333 kJ/mol (UV-VIS). Complimentary DSC studies indicate that the denaturation is irreversible, giving endotherms strongly dependent upon the heating scan rates, suggesting a kinetically controlled process. Dependence on protein concentration suggests that the two components in the endotherms are due to oligomeric dissociation effect upon denaturation. Activation energies are in the range 200-560 kJ/mol. The mid-point transition temperatures were in the range 50-65 degrees C. Cyanomet-HbGp shows higher mid-point temperatures as well as activation energies, consistent with its higher stability. DSC data are reported for the first time for an extracellular hemoglobin. (C) 2010 Elsevier B.V. All rights reserved.

Recovery and upgrading bovine rumen protein by extrusion: Effect of lipid content on protein disulphide cross-linking, solubility and molecular weight

Bovine rumen protein with two levels of residual lipids (1.9% or 3.8%) was subjected to thermoplastic extrusion under different temperatures and moisture contents. Protein Solubility in different buffers, disulphide cross-linking and molecular weight distribution were determined on the extrudates. After extrusion, samples with 1.9% residual lipids content had a higher concentration of protein insoluble by undetermined forces, irrespective of feed moisture and processing temperature used. Lipid content of 3.8% in the feed material resulted in more protein participating in the extrudate network through non-covalent interactions (hydrophobic and electrostatic) and disulphide bonds. A small dependency of the extrusion process on moisture and temperature and a marked dependency on lipid content, especially phospholipid, was observed, Electrophoresis under non-reducing conditions showed that protein extrusion with low feed moisture promoted high molecular breakdown inside the barrel, probably due to intense shear force, and further protein aggregation at the die end. (C) 2009 Elsevier Ltd. All rights reserved.

Amaranth protein presents cholesterol-lowering effect

This study describes amaranth`s protein cholesterol-lowering effect and investigates its mechanisms hypercholesterolaemia was induced in male hamsters through diet rich in casein (300 g/kg diet) containing regular levels of cholesterol (0.5 kg/g) fed during 3 weeks. Animals were divided into three groups and fed ad libitum diets for 4 weeks containing as the sole source of protein: casein (control), amaranth protein isolate or, casein + amaranth protein isolate. Plasma concentrations of cholesterol and triacylglycerols were measured at four different points: at the beginning of the study. after hypercholesterolaemia was induced, in the first week and then at the end of the experimental diet period. The reduction of the total plasma cholesterol concentration at the end of experimental period for animals fed on diets containing amaranth protein isolate pure and with casein were 27% (P < 0.05) and 48% (P < 0.05). respectively, being the non-HDL fractions the most affected. Digestibility of protein as well as excretion of cholesterol and bile acid, were investigated as the possible mechanisms for this significant hypocholesterolaemic effect. Cholesterol excretion was related to the hypocholesterolaemia but could not explain all the observed reduction. Our findings suggest that amaranth protein has a metabolic effect on endogenous cholesterol metabolism. (C) 2009 Elsevier Ltd. All rights reserved.

Selection of operational parameters for the production of instant soy protein isolate by pulsed fluid bed agglomeration

The objective of this study was to select the optimal operational conditions for the production of instant soy protein isolate (SPI) by pulsed fluid bed agglomeration. The spray-dried SPI was characterized as being a cohesive powder, presenting cracks and channeling formation during its fluidization (Geldart type A). The process was carried out in a pulsed fluid bed, and aqueous maltodextrin solution was used as liquid binder. Air pulsation, at a frequency of 600 rpm, was used to fluidize the cohesive SPI particles and to allow agglomeration to occur. Seventeen tests were performed according to a central composite design. Independent variables were (i) feed flow rate (0.5-3.5 g/min), (ii) atomizing air pressure (0.5-1.5 bar) and (iii) binder concentration (10-50%). Mean particle diameter, process yield and product moisture were analyzed as responses. Surface response analysis led to the selection of optimal operational parameters, following which larger granules with low moisture content and high process yield were produced. Product transformations were also evaluated by the analysis of size distribution, flowability, cohesiveness and wettability. When compared to raw material, agglomerated particles were more porous and had a more irregular shape, presenting a wetting time decrease, free-flow improvement and cohesiveness reduction. (C) 2010 Elsevier B.V. All rights reserved.

Biodegradable Films Based on Blends of Gelatin and Poly (Vinyl Alcohol): Effect of PVA Type or Concentration on Some Physical Properties of Films

The aim of this work was to develop biodegradable films based on blends of gelatin and poly (vinyl alcohol) (PVA), without a plasticizer. Firstly, the effect of five types of PVA with different degree of hydrolysis (DH) on the physical properties of films elaborated with blends containing 23.1% PVA was studied. One PVA type was then chosen for the study of the effect of the PVA concentration on the mechanical properties, color, opacity, gloss, and water solubility of the films. The five types of PVA studied allowed for films with different characteristics, but with no direct relationship with the DH of the PVA. Therefore, the PVA Celvol (R) 418 with a DH = 91.8% was chosen for the second part, because they produced films with greater tensile strength. The PVA concentration affected all studied properties of films. These results could be explained by the results of the DSC and FTIR analyses, which showed that some interactions between the gelatin and the PVA occurred depending on the PVA concentration, affecting the crystallinity of the films.

Prolonged exposure to palmitate impairs fatty acid oxidation despite activation of AMP-activated protein kinase in skeletal muscle cells

The aim of this study was to investigate the chronic effects of palmitate on fatty acid (FA) oxidation, AMPK/ACC phosphorylation/activation, intracellular lipid accumulation, and the molecular Mechanisms involved in these processes in skeletal muscle cells. Exposure of L6 myotubes for 8 h to 200, 400, 600, and 800 mu M of palmitate did rot affect cel viability but significantly reduced FA oxidation by similar to 26.5%, similar to 43.5%, similar to 50%, and similar to 47%, respectively. Interestingly, this occurred despite significant increases in AMPK (similar to 2.5-fold) and ACC (similar to 3-fold) phosphorylation and in malonyl-CoA decarboxylase activity (similar to 38-60%). Low concentrations of palmitate (50-100 mu M) caused an increase (similar to 30%) in CPT-I activity. However, as the concentration of palmitate increased, CPT-I activity decreased by similar to 32% after exposure for 8 h to 800 mu M of palmitate. Although FA uptake was reduced (similar to 35%) in cells exposed to increasing, palmitate concentrations, intracellular lipid accumulation increased in a dose-dependent manner, reaching values similar to 2.3-, similar to 3-, and 4-fold higher than control in muscle cells exposed to 400, 600, and 800 mu M palmitate, respectively. Interestingly, myotubes exposed to 400 mu M of palmitate for 1h increased basal glucose uptake and glycogen synthesis by similar to 40%. However, as time of incubation in the presence of palmitate progressed from 1 to 8h, these increases were abolished and a time-dependent inhibition of insulin-stimulated glucose uptake (similar to 65%) and glycogen synthesis (30%) was observed in myotubes. These findings may help explain the dysfunctional adaptations that occur in glucose and FA Metabolism in skeletal muscle under conditions of chronically elevated circulating levels of non-esterified FAs. Such as in obesity and Type 2 Diabetes.