Efeito da deficiência de energia na dieta sobre a população de protozoários ciliados do rúmen de bovinos

Ten young rumen-cannulated crossbred steers were randomly divided into two groups: a control group (C; n=4), which was fed a balanced diet for daily weight gain of 900g; and a pronounced energy-deprived group (PED; n=6), receiving 30% less of the required energy for maintenance. After 140 days of these alimentary regimes, rumen fluid and urine samples were collected for biochemical and functional tests, before feeding and at 1, 3, 6, and 9 hours after feeding. The energy-deprivation diet caused a significant reduction in the number of Entodinium, Eodinium, Isotricha, Dasytricha, Eremoplastron, Eudiplodinium, Metadinium, Charonina, Ostracodinium, and Epidinium protozoa. There was no effect of the time of sampling in both groups on the total number of ciliates in rumen fluid. A higher number of protozoan forms in binary division were recorded in the control group, at the 6th and 9th hours after feeding (P<0.019). There was a high positive correlation between the total count of protozoans in rumen fluid and glucose fermentation, ammonia, and urinary allantoin excretion index; and a negative correlation between the total count of protozoa and metilene blue reduction, and a medium correlation between the total count of protozoa and total volatile fatty acids concentration. The determination of the protozoa populations does not imply in the use of complex and hard-to-execute techniques, although it is time consuming and needs practice. This exam particularly helps in clinical expected diagnosis.Foram utilizados 10 novilhos mestiços com cânula ruminal, distribuídos em dois grupos: no grupo controle (C; n=4) receberam dieta balanceada para ganho diário de 900g; no grupo tratado com carência pronunciada de energia (CP; n=6), receberam dieta com 30% a menos do nível de mantença em energia. Após 140 dias sob esses regimes de alimentação, foram coletadas amostras do fluido ruminal e urina, para realização de provas bioquímicas e funcionais, antes e às 1, 3, 6 e 9 horas após o fornecimento do alimento. A carência energética resultou em diminuição significativa na quantidade dos protozoários Entodinium, Eodinium, Isotricha, Dasytricha, Eremoplastron, Eudiplodinium, Metadinium, Charonina, Ostracodinium e Epidinium. Não houve efeito da hora de coleta sobre o total de ciliados nos grupos C e CP. Maior número de formas em divisão binária foi registrado no grupo C, na sexta e nona horas pós-alimentação (P<0,019). Observaram-se altas correlações positivas entre a contagem total de protozoários e a fermentação de glicose, amônia e o índice de excreção urinária de alantoína e negativa entre a contagem total de protozoários e a redução do azul de metileno, e correlação média entre a contagem total de protozoários e os ácidos graxos voláteis totais. A determinação da população de protozoários do rúmen é um método simples de avaliação, além de que particularmente auxilia o diagnóstico clínico da função ruminal

Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification – a comparative study

Latex nanoparticles comprising cationically charged coronas and hydrophobic cores with different glass transition temperatures (Tg) have been prepared by surfactant-free, RAFT-mediated emulsion polymerization, where the particles form through a polymerization-induced self-assembly (PISA) type mechanism. Poly(2-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) was utilized as a hydrophilic macroRAFT agent for the polymerization of methyl methacrylate (MMA) or n-butyl methacrylate (nBMA), respectively, resulting in two different latexes, with either a core of high (PMMA) or low (PnBMA) Tg polymer. By varying the molar mass of the hydrophobic block, latexes of different sizes were obtained (DHca. 40–120 nm). The adsorption of the latexes to cellulose model surfaces and cellulose nanofibrils (CNF) was studied using quartz crystal microbalance with dissipation monitoring (QCM-D). The surfaces with adsorbed PnBMA latexes yielded hydrophobic surfaces both before and after annealing, whereas surfaces with adsorbed PMMA latex became hydrophobic only after annealing, clearly showing the influence of the Tg of the core. The latexes were also used to modify macroscopic cellulose in the form of filter papers. Similar to the CNF surfaces, no annealing was required to achieve hydrophobic surfaces with PnBMA latexes. Finally, nanocomposites of CNF and the polymer nanoparticles were prepared through a one-pot mixing procedure. It was found that the largest synthesized PMMA latex (120 nm) facilitated a more strainable CNF network at 50% relative humidity, with a nearly 200% increase in strain at break compared to the neat CNF reference film as well as to the composite films with PnBMA latexes or to the smaller sized PMMA latexes. This difference was attributed to the spherical shape and rigidity of the large PMMA latex nanoparticles during composite formation. This highly interesting result should indeed be considered in the future design of novel biocomposites.</p

Silver sulfadiazine eradicates antibiotic-tolerant Staphylococcus aureus and Pseudomonas aeruginosa biofilms in patients with infected diabetic foot ulcers

Infections are among the most frequent and challenging events in diabetic foot ulcers (DFUs). Pathogenic bacteria growing in biofilms within host tissue are highly tolerant to environmental and chemical agents, including antibiotics. The present study was aimed at assessing the use of silver sulfadiazine (SSD) for wound healing and infection control in 16 patients with DFUs harboring biofilm-growing Staphylococcus aureus and Pseudomonas aeruginosa. All patients received a treatment based on a dressing protocol including disinfection, cleansing, application of SSD, and application of nonadherent gauze, followed by sterile gauze and tibio-breech bandage, in preparation for toilet surgery after 30 days of treatment. Clinical parameters were analyzed by the T.I.M.E. classification system. In addition, the activity of SSD against biofilm-growing S. aureus and P. aeruginosa isolates was assessed in vitro. A total of 16 patients with S. aureus and P. aeruginosa infected DFUs were included in the study. Clinical data showed a statistically significant (p &lt; 0.002) improvement of patients’ DFUs after 30 days of treatment with SSD with significant amelioration of all the parameters analyzed. Notably, after 30 days of treatment, resolution of infection was observed in all DFUs. In vitro analysis showed that both S. aureus and P. aeruginosa isolates developed complex and highly structured biofilms. Antibiotic susceptibility profiles indicated that biofilm cultures were significantly (p ≤ 0.002) more tolerant to all tested antimicrobials than their planktonic counterparts. However, SSD was found to be effective against fully developed biofilms of both S. aureus and P. aeruginosa at concentrations below those normally used in clinical preparations (10 mg/mL). These results strongly suggest that the topical administration of SSD may represent an effective alternative to conventional antibiotics for the successful treatment of DFUs infected by biofilm-growing S. aureus and P. aeruginosa

Mass transfer assessment and kinetic investigation of biphasic catalytic systems

Efficient catalyst recovery and recycling is still a major challenge for the development of homogeneous catalysis. In the 80’s, the concept of biphasic catalysis, in which the catalyst is confined into a solvent immiscible with the products, has opened new perspectives for transition metal complex driven homogeneous catalysis, after the industrial success of the Ruhrchemie/Rhone-Poulenc process operating the rhodium-catalyzed hydroformylation of propene in water. However, the low solubility of long-chain a-olefins has limited the scope of hydrosoluble catalysts for this reaction. To overcome this problem, various strategies have been developed since then, which consist in replacing water by a more suitable solvent or using additives/ligands able to increase the substrate solubility or create a favorable microenvironment in the aqueous phase. Apart from the screening/tailoring of solvent and ligand, the determination of an adequate kinetic model and the assessment of the mass transfer role is of great importance for the design and optimization of the multiphase reaction system. This presentation gives an account of collaborative works between chemical engineering and chemistry teams to address these issues for two different biphasic catalysis approaches: catalyst immobilization in ionic liquids and use of amphiphilic polymer ligands. The hydroformylation of oct-1-ene by rhodium complexes was selected as model reaction for the developed methodology. This includes the thermodynamic study of the complex reaction medium (gas-liquid and liquid-liquid equilibria), the thorough investigation of the effect of process parameters to evaluate the location of the catalytic act and the interfacial mass transfer resistance, the discrimination and identification of intrinsic kinetic models (derived from elementary reaction steps) and their coupling with (gas-liquid) mass transfer under low stirring conditions. In the first example, the role of the ionic liquids as solvents for biphasic catalysis was specified, by characterizing the solubility of both gaseous and organic substrates, and a detailed kinetic model was able to accurately describe the time-concentration profiles of reactants and products (1-octene,internal octenes, n-nonanal and branched aldehydes) measured in the organic phase. TOF values could be further improved (up to 560 h-1) by supporting the ionic liquid phase onto a silica gel support. In the second example, the proof of concept of cross-linked micelles as efficient supports for aqueous phase catalysis was established, demonstrating that the reaction occurs within the nano-objects with fast exchange with the organic phase. The study also provided clues for their optimization: a low functionalization degree and a nanogel structure embedding the phosphine moieties were proved to improve the catalytic activity and reduce the metal leaching, respectively. These innovative ligands yielded TOF in the range of 350 to 650 h-1 and linear/branched aldehyde ratios between 3 and 6. The Rh loss could be reduced to 0.1 ppm with adequate pH and temperature conditions

Influence of structure and solubility of chain transfer agents on the RAFT control of dispersion polymerisation in scCO2

Reversible addition-fragmentation chain transfer (RAFT) dispersion polymerisation of methyl methacrylate (MMA) is performed in supercritical carbon dioxide (scCO2) with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight. Kinetic studies of the polymerisation in scCO2also confirm these data. By contrast, only poor control of MMA polymerisation is obtained in toluene solution, as would be expected for this CTA which is better suited for acrylates. In this regard, we select a range of CTAs and use them to determine the parameters that must be considered for good control in dispersion polymerisation in scCO2. A thorough investigation of the nucleation stage during the dispersion polymerisation reveals an unexpected “in situtwo-stage” mechanism that strongly determines how the CTA works. Finally, using a novel computational solvation model, we identify a correlation between polymerisation control and degree of solubility of the CTAs. All of this ultimately gives rise to a simple, elegant and counterintuitive guideline to select the best CTA for RAFT dispersion polymerisation in scCO

Efficacy of a brief multifactorial adherence-based intervention on reducing the blood pressure of patients with poor adherence: protocol for a randomized clinical trial

<p>Abstract</p> <p>Background</p> <p>Lowering of blood pressure by antihypertensive drugs reduces the risks of cardiovascular events, stroke, and total mortality. However, poor adherence to antihypertensive medications reduces their effectiveness and increases the risk of adverse events. In terms of relative risk reduction, an improvement in medication adherence could be as effective as the development of a new drug.</p> <p>Methods/Design</p> <p>The proposed randomized controlled trial will include patients with a low adherence to medication and uncontrolled blood pressure. The intervention group will receive a multifactorial intervention during the first, third, and ninth months, to improve adherence. This intervention will include motivational interviews, pill reminders, family support, blood pressure self-recording, and simplification of the dosing regimen.</p> <p>Measurement</p> <p>The primary outcome is systolic blood pressure. The secondary outcomes are diastolic blood pressure, proportion of patients with adequately controlled blood pressure, and total cost.</p> <p>Discussion</p> <p>The trial will evaluate the impact of a multifactorial adherence intervention in routine clinical practice. Ethical approval was given by the Ethical Committee on Human Research of Balearic islands, Spain (approval number IB 969/08 PI).</p> <p>Trial registration</p> <p>Current controlled trials ISRCTN21229328</p