1000 resultados para Ricardo Güiraldes
Resumo:
Inulin was used as a prebiotic to improve quality of skim milk fermented by pure cultures of Lactobacillus acidophilus Lactobacillus rhamnosus Lactobacillus bulgaricus and Bifidobacterium lactis binary co-cultures with Streptococcus thermophilus or a cocktail containing all them Inulin supplementation to pure cultures lowered the generation time with particular concern to S thermophilus and L acidophilus The generation time of all micro-organisms decreased in the following order mono-cultures co-cultures cocktail It was demonstrated a synergism between S thermophilus and the other strains and a bifidogenic effect of inulin Enumerations of L rhamnosus in cocktail markedly decreased compared to co-cultures likely because of greater competition for the same substrates The results of this work highlight the industrial potential of the cocktail mainly in terms of fermentation acceleration (C) 2010 Elsevier Ltd All rights reserved
Resumo:
Lactulose can be considered as a prebiotic, which is able to stimulate healthy intestinal microflora. In the present work, the use of this ingredient in fermented milk improved quality of skim milk fermented by Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus and Bifidobacterium lactis in co-culture with Streptococcus thermophilus. Compared to control fermentations without lactulose, the addition of such a prebiotic in skim milk increased the counts of all probiotics, with particular concern to B. lactis (bifidogenic effect), the acidification rate and the lactic acid acidity, and concurrently reduced the time to complete fermentation (t(pH4.5)) and the pH at the end of cold storage for 1 to 35 days. (c) 2010 Elsevier B.V. All rights reserved.
Resumo:
Inulin behaved as a prebiotic to improve firmness of skim milk fermented by (a) pure cultures of Lactobacillus acidophilus (La), Lactobacillus rhamnosus (Lr), Lactobacillus bulgaricus (Lb) and Bifidobacterium lactis (Bl), (b) binary co-cultures of them with Streptococcus thermophilus (St), or (c) a cocktail containing all them. Inulin addition to co-cultures and cocktail enhanced products firmness, either after 1 day (D1) or 7 days (D7) of cold storage, likely due to the increase in microbial growth induced by metabolic interactions among lactic acid bacteria and partial inulin metabolization. Co-culture firmness did in fact range from 0.33 N without inulin (St-Lb) after D1 and 0.55 N with inulin (St-Lr) after D7. Also cocktail cultures exhibited high values of firmness, ranging, as an average, from 0.43 N (D1) to 0.46 N (D7), which suggests that they could have been potentiated by the reciprocal synergistic effects of microorganisms in complex mixture. (C) 2011 Elsevier Ltd. All rights reserved.
Resumo:
Clavulanic acid (CA) is a potent inhibitor of beta-lactamases, produced by some resistant pathogenic microorganisms, which allows efficient treatment of infectious diseases. The kinetic and thermodynamic parameters of CA production by a new isolate of Streptomyces DAUFPE 3060 and its degradation were evaluated. The effect of temperature on the system was investigated in the range 24-40 degrees C adopting an overall model accounting for (a) the Arrhenius-type formation of CA by fermentation, (b) the hypothetical reversible unfolding of the enzyme limiting the overall metabolism, and (c) the irreversible first-order degradation of CA. The higher rates of CA formation (k(CA) = 0,107 h(-1)) and degradation (k(d) = 0.062 h(-1)) were observed at 32 and 40 degrees C, respectively. The main thermodynamic parameters of the three above hypothesized events were estimated. In particular, the activation parameters of degradation (activation energy = 39.0 kJ/mol; Delta H(d)* = 36.5 kJ/mol; Delta S(d)* = -219.7 J/(mol K); Delta G(d)* = 103.5 kJ/mol) compare reasonably well with those reported in the literature for similar system without taking into account the other two events. (C) 2009 Elsevier Inc. All rights reserved.
Resumo:
Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by co-cultures and pure Cultures of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus and Bifidobacterium lactis with Streptococcus thermophilus. We compared, either in the presence or absence of 4 g inulin/100 g, the results of the main kinetic parameters, specifically the generation time (t(g)), the maximum acidification rate (V(max)). and the times to reach V(max) (t(max)), to attain pH 5.0 (t(pH5.0)) and to complete the fermentation (t(pH4.5)). Post-acidification, lactic acid formation and cell counts were also determined and compared, either 1 day after the fermentation was complete or after 7 day storage at 4 degrees C. In general, inulin addition to the milk increased in co-cultures V(max), decreased t(max), t(g) and t(pH4.5), favored post-acidification, exerted a bifidogenic effect, and preserved almost intact cell viability during storage. In addition, S. thermophilus was shown to stimulate the metabolism of the other lactic bacteria. Contrary to co-cultures, most of the effects in pure Cultures were not statistically significant. The most important aspect of this paper is the use of the generation time as a toot to investigate the microbial response to inulin addition. (c) 2009 Elsevier Ltd. All rights reserved.
Resumo:
We investigated the effect of inulin as a prebiotic on the production of probiotic fibre-enriched fermented milk. The kinetics of acidification of inulin-supplemented milk (0, 0.01, 0.02 and 0.04 g/g), as well as probiotic survival, pH and firmness of fermented milk stored at 4 degrees C for 24 h and 7 days after preparation were examined. Probiotic fibre-enriched fermented milk quality was influenced both by the amount of inulin and by the co-culture composition. Depending on the co-culture, inulin addition to milk influenced acidification kinetic parameters, probiotic counts, pH and the firmness of the product.
Resumo:
Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by Lactobacillus acidophilus (La), Lactobacillus rhamnosus (Lr), Lactobacillus bulgaricus (Lb) and Bifidobacterium lactis (BI) with Streptococcus thermophilus (St), either in binary co-cultures or in cocktail containing all microorganisms. We compared, either in the presence of 40 mg inulin g(-1) or not, the results of the maximum acidification rate (V(max)) and the times to reach it (t(max)), to reach pH 5.0 (t(PH5.0)) and to complete the fermentation (t(f)). Post-acidification, lactic acid formation and cell counts were also compared after either 1 day (D1) or 7 days of storage at 4 degrees C (N). In co-culture, inulin addition to the milk increased V(max), decreased t(max) and t(f), favored post-acidification and exerted a bifidogenic effect. S. thermophilus proved to stimulate the metabolism of the other lactic bacteria and enhanced the product features. After D7, a significant prebiotic effect of inulin was observed in all co-cultures. Either after D1 or D7, the enumerations of Lr and BI in mixed culture markedly decreased compared to their respective co-cultures because of greater competition for the same substrates. (C) 2008 Elsevier Ltd. All rights reserved.
Resumo:
The simultaneous effects of different binary co-cultures of Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus rhamnosus and Bifidobacterium lactis with Streptococcus thermophilus and of different prebiotics on the production of fermented milk were investigated in this paper. In particular, we determined and compared the kinetics of acidification of milk either as such or supplemented with 4% (w/w) maltodextrin, oligofructose and polydextrose, as well as the probiotic survival, chemical composition (pH, lactose, lactic acid and protein contents), fatty acids profile and conjugate linoleic acid (CIA) content of fermented milk after storage at 4 degrees C for 24 h. Fermented milk quality was strongly influenced both by the co-culture composition and the selected prebiotic. Depending on the co-culture, prebiotic addition to milk influenced to different extent kinetic acidification parameters. All probiotic counts were stimulated by oligofructose and polydextrose, and among these B. lactis always exhibited the highest counts in all supplemented milk samples. Polydextrose addition led to the highest post-acidification. Although the contents of the main fatty acids were only barely influenced. the highest amounts of conjugated linoleic acid (38% higher than in the control) were found in milk fermented by S. thermophilus-L. acidophilus co-culture and supplemented with maltodextrin. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
The objective of this study was to investigate the ergogenic effects of caffeine on motor performance of judo female athletes. Thirteen female athletes (17.6 +/- 1.6 years, 58.3 +/- 11.4 kg, 162 +/- 4.1 cm, 22.5 +/- 4 kg/m(2)), registered in the State Federation of Judo for at least two years, participated in this study. The motor performance was assessed using the Special Judo Fitness Test (SJFT), from which was considered the number of throws in each block, the total number of throws, recovery and final heart rate (HR) and final score in SJFT. The subjects were tested in two different conditions, after ingestion of gelatin capsules of caffeine (6 mg.kg(-1)) or placebo (dextrose) 60 minutes before testing in a randomized double-blind, crossover study. The number of throws in each block did not differs between the caffeine (CAF) and placebo (PL) conditions (Block A: 4.53 +/- 0.51 CAF and 4.46 +/- 0.51 PL; Block B: 8.3 +/- 0.63 CAF and 8.23 +/- 0.72 PL; Block C: 7.23 +/- 0.59 CAF and 7.46 +/- 0.77 PL), as well as the total number of throws (20.07 +/- 1.18 CAF and 20.15 +/- 1.67 PL), HR (Final: 190.3 +/- 9.63 bpm CAF and 190.69 +/- 9.19 bpm PL; Recovery 162.07 +/- 13.78 bpm CAF and 164.3 +/- 9.64 bpm PL) and final score in SJFT (17.59 +/- 1.4 CAF and 17.75 +/- 1.98 PL). Ingestion of caffeine did not improve performance during high intensity and short duration exercise in judo fighters
Resumo:
Phenolic compounds are found in seaweed species together with other Substances presenting antioxidant activity. The objective of this work was to evaluate the antioxidant activity of the free phenolic acids (FPA) fraction from the seaweed Halimeda monile, and its activity to protect the expression of hepatic enzymes in rats, under experimental CCI(4) injury. The antioxidant activity was measured by the DPPH method. The FPA fraction (80 mg/kg, p.o.) was administered during 20 consecutive days to rats. The peroxidation was performed by thiobarbituric acid reactive substances (TBARS). The SOD and CAT enzymatic expressions were measured by RT/PCR. The histology technique was used to evaluate liver injuries. The expression of both, CAT and SOD genes, was more preserved by FPA. Only partial injury could be observed by histology in the liver of rats receiving FPA as compared with the control group; and CCI(4) administration induced 60% more peroxidation as compared with the rats receiving FPA. These data suggest that FPA could modulate the antioxidant enzymes and oxidative status in the liver through protection against adverse effects induced by chemical agents.
Resumo:
In addition to adenosine triphosphate (ATP) production, mitochondria have been implicated in the regulation of several physiological responses in plants, such as programmed cell death (PCD) activation. Salicylic acid (SA) and reactive oxygen species (ROS) are essential signaling molecules involved in such physiological responses; however, the mechanisms by which they act remain unknown. In non-photosynthesizing tissues, mitochondria appear to serve as the main source of ROS generation. Evidence suggests that SA and ROS could regulate plant PCD through a synergistic mechanism that involves mitochondria. Herein, we isolate and characterize the mitochondria from non-photosynthesizing cell suspension cultures of Rubus fruticosus. Furthermore, we assess the primary site of ROS generation and the effects of SA on isolated organelles. Mitochondrial Complex III was found to be the major source of ROS generation in this model. In addition, we discovered that SA inhibits the electron transport chain by inactivating the semiquinone radical during the Q cycle. Computational analyses confirmed the experimental data, and a mechanism for this action is proposed.
Resumo:
Fatty acid synthase (FASN) is the metabolic enzyme responsible for the endogenous synthesis of the saturated long-chain fatty acid, palmitate. In contrast to most normal cells, FASN is overexpressed in a variety of human cancers, including cutaneous melanoma, in which its levels of expression are associated with tumor invasion and poor prognosis. We have previously shown that FASN inhibition with orlistat significantly reduces the number of spontaneous mediastinal lymph node metastases following the implantation of B16-F10 mouse melanoma cells in the peritoneal cavity of C57BL/6 mice. In this study, we investigate the biological mechanisms responsible for the FASN inhibition-induced apoptosis in B16-F10 cells. Both FASN inhibitors, cerulenin and orlistat, significantly reduced melanoma cell proliferation and activated the intrinsic pathway of apoptosis, as demonstrated by the cytochrome c release and caspase-9 and -3 activation. Further, apoptosis was preceded by an increase in both reactive oxygen species production and cytosolic calcium concentrations and independent of p53 activation and mitochondrial permeability transition. Taken together, these findings demonstrate the mitochondrial involvement in FASN inhibition-induced apoptosis in melanoma cells. Laboratory Investigation (2011) 91, 232-240; doi:10.1038/labinvest.2010.157; published online 30 August 2010
Resumo:
This paper reports theoretical and experimental studies of gas-phase fragmentation reactions of four naturally occurring isoflavones. The samples were analyzed in negative ion mode by direct infusion in ESI-QqQ, ESI-QqTOF and ESI-Orbitrap systems. The MS/MS and MS(n) spectra are in agreement with the fragmentation proposals and high-resolution analyses have confirmed the formulae for each ion observed. As expected, compounds with methoxyl aromatic substitution have showed a radical elimination of center dot CH(3) as the main fragmentation pathway. A second radical loss (center dot H) occurs as previously observed for compounds which exhibit a previous homolytic center dot CH(3) cleavage (radical anion) and involves radical resonance to stabilize the anion formed. However, in this study we suggest another mechanism for the formation of the main ions, on the basis of the enthalpies for each species. Compounds without methoxy substituent dissociate at the highest energies and exhibit the deprotonated molecule as the most intense ion. Finally, energy-resolved experiments were carried out to give more details about the gas-phase dissociation reaction of the isoflavones and the results are in agreement with the theoretical approaches. Copyright (C) 2011 John Wiley & Sons, Ltd.
Resumo:
Objectives In the present study we investigated the anti nociceptive, anti-inflammatory and antipyretic effects of 7-hydroxycoumarin (7-HC) in animal models. Methods The effects of oral 7-HC were tested against acetic acid-induced writhing, formalin test, tail flick test, complete Freund`s adjuvant (CFA)-induced hypemociception, carrageenan-induced paw oedema, lipopolysaccharide-induced fever and the rota rod test. Key findings 7-HC (3-60 mg/kg) produced a dose-related antinociception against acetic acid-induced writhing in mice and in the formalin test. In contrast, treatment with 7-HC did not prevent thermal nociception in the tail flick test. A single treatment with 7-HC, 60 mg/kg, produced a long-lasting antinociceptive effect against CFA-induced hypernociception, a chronic inflammatory pain stimulus. Notably, at 60 mg/kg per day over 4 days the administration of 7-HC produced a continuous antinociceptive effect against CFA-induced hypernociception. 7-HC (30-120 mg/kg) produced anti-inflammatory and antipyretic effects against carrageenan-induced inflammation and lipopolysaccharide-induced fever, respectively. Moreover, 7-HC was found to be safe with respect to ulcer induction. In the rota rod test, 7-HC-treated mice did not show any motor performance alterations. Conclusions The prolonged antinociceptive and anti-inflammatory effects of 7-HC, in association with its low ulcerogenic activity, indicate that this molecule might be a good candidate for development of new drugs for the control of chronic inflammatory pain and fever.
Resumo:
The use of biodegradable natural polymers has increased due to the over-solid packaging waste. In this study, a chemical modification of the casein molecule was performed by Maillard reaction, and the modified polymer was evaluated by polyacrylamide gel electrophoresis (PAGE), thermogravimetry/derivative thermogravimetry (TG/DTG), FT-IR, and (1)H-NMR spectroscopy. Subsequently, films based on the modified casein were obtained and characterized by mechanical analysis, water vapor transmission, and erosion behavior. The PAGE results suggested an increase of molecular mass of the modified polymer, and FT-IR spectroscopy data indicated inclusion of C-OH groups into this molecule. The TG/DTG curves of modified casein presented a different thermal decomposition profile compared to the individual compounds. Mechanical tests showed that the chemical modification of the casein molecules provided higher elongation rates (45.5%) to the films, suggesting higher plasticity, than the original molecules (13.4%). The modified casein films presented higher permeability (0.505 +/- A 0.006 mu g/h mm(3)) than the original polymer (0.387 +/- A 0.006 mu g/h mm(3)) films at 90% relative humidity (RH). In pH 1.2, modified casein films presented higher erosion rates (32.690 +/- A 0.692%) than casein films (19.910 +/- A 2.083%) after 8 h, suggesting an increased sensibility for erosion of the modified casein films in acid environment. In water (pH 7.0), the films erosion profiles were similar. Those findings indicate that the modification of molecule by Maillard reaction provided films more plastic, hydrophilic, and sensitive to erosion in acid environment, suggesting that a new polymer with changed properties was founded.