Novel bacteriocins produced by Lactobacillus fermentum strains with bacteriostatic effects in milk against selected indicator microorganisms.

The aim of this work was to isolate and characterize bacteriocins produced by 2 Lactobacillus fermentum strains isolated from artisanal Mexican Cocido cheese. Fractions (F ≤3 kDa) obtained from cell-free supernatants of Lb. fermentum strains J23 and J32 were further fractionated by reversed-phase HPLC on a C18 column. Antimicrobial activities of F ≤3 kDa and bacteriocin-containing fractions (BCF), obtained from fractionation of F ≤3 kDa against 4 indicator microorganisms, were determined by the disk diffusion method and growth inhibition in milk. Subsequently, isolated BCF were analyzed by reversed-phase HPLC tandem mass spectrometry. Results showed that BCF presented antimicrobial activity against the 4 indicator microorganisms tested. For J23, one of the fractions (F3) presented the highest activity against Escherichia coli and was also inhibitory against Staphylococcus aureus, Listeria innocua, Salmonella Typhimurium, and Salmonella Choleraesuis. Similarly, fractions F3 and F4 produced by J32 presented antimicrobial activity against all indicator microorganisms. Furthermore, generation time and growth rate showed that F3 from J23 presented significantly higher antimicrobial activity against the 4 indicator microorganisms (2 gram-positive and 2 gram-negative) when inoculated in milk compared with F3 from J32. Interestingly, this fraction presented a broader antimicrobial spectrum in milk than nisin (control). Reversed-phase HPLC tandem mass spectrometry analysis revealed the presence of several peptides in BCF; however, F3 from J23 that was the most active fraction of all presented only 1 bacteriocin. The chemical characterization of this bacteriocin suggested that it was a novel peptide with 10 hydrophobic AA residues in its sequence and a molecular weight of 2,056 Da. This bacteriocin and its producing strain, J23, may find application as a biopreservative against these indicator microorganisms in dairy products.

Functional Exercise Versus Specific Pelvic Floor Exercise: Observational Pilot Study in Female University Students.

OBJECTIVES: To evaluate the electromyographic (EMG) activity of the pelvic floor musculature (PFM) that takes place when performing the functional movement screen (FMS) exercise, comparing it with the activation in the maximum voluntary contraction of PFM in the supine position (MVC-SP) and standing (MVC-ST). MATERIAL AND METHODS: A descriptive, observational study conducted in two phases. In the first study phase, the baseline EMG activity of PFM was measured in the supine position and standing during MVC-SP and MVC-ST and during the execution of the seven exercises that make up the FMS. In the second phase of the study, the baseline EMG activity of PFM was measured in the supine position and standing during MVC-SP and MVC-ST and during the FMS exercise that produced the most EMG in the pilot phase: trunk stability push-up (PU). ANOVA, Friedman's and Pearson's tests were used. RESULTS: All FMS exercises performed in the pilot phase showed a value below 100% maximum voluntary contraction (MVC) except PU, which presented an average value of 101.3 µv (SD = 54.5): 112% MVC (SD = 37.6). In the second phase of the study, it was observed that there were no significant differences (p = 0.087) between the three exercises performed: MVC-SP, MVC-ST and PU (39.2 µv (SD = 10.4), 37.5 µv (SD = 10.4) and 40.7 µv (SD = 10.2), respectively). CONCLUSIONS: There is no evidence of the existence of significant differences in EMG activation in PFM among the three exercises analysed: MVC-SP, MVC-ST and PU. The results show better EMG values in the functional exercise of PU.

Influence of the Therapeutic Alliance on the Rehabilitation of Stroke: A Systematic Review of Qualitative Studies.

The therapeutic alliance is a fundamental component of rehabilitation in order to achieve effective outcomes. However, what develops, maintains or hinders this relationship has not been sufficiently explored. The aim of this systematic review is to recognize the role of the therapeutic alliance in the neurological rehabilitation process. A search for articles was carried out in the databases PubMed, Web of Science, SCOPUS, CINAHL, APA PsycInfo, OTseeker and Dialnet. They were selected according to the eligibility criteria. Internal quality assessment of the articles was measured with the Consolidated Criteria for Reporting Qualitative Research (COREQ). The systematic review was registered in PROSPERO (ID 346523). The search in the databases identified 1596 articles, from which 9 different studies were finally included in the systematic review, reflecting the limitations of studies in this field. All studies are qualitative, from the point of view of the patients themselves, their relatives and healthcare professionals. The total sample of the included studies is 182 participants (96 health professionals, 76 users and 10 relatives). Semi-structured interviews, focus group discussions and written reflections were mainly used to collect the data. In conclusion, the therapeutic alliance can be an active component in the post-stroke rehabilitation process. Being recognized as a person, collaboration with the therapeutic team, empathy, empowerment, confidence, professional skills, maintenance of hope and the role of the family have been identified as aspects that can have an influence on the therapeutic alliance.

In Vitro Antithrombotic and Hypocholesterolemic Activities of Milk Fermented with Specific Strains of Lactococcus lactis.

Milk fermented with specific lactic acid bacteria (LAB) was reported to be a rich source of metabolites, such as peptides with different biological activities that may have a positive effect on cardiovascular health. Thus, in this study, the antithrombotic and hypocholesterolemic activities of fermented milk with specific strains of Lactococcus lactis were investigated before and after exposure to a simulated gastrointestinal digestion (SGD) model. The inhibition of thrombin-induced fibrin polymerization (IC50 peptide concentration necessary to inhibit thrombin activity by 50%), anticoagulant activity, inhibition of micellar solubility of cholesterol and bile acid binding capacity of water soluble fractions (WSF) <3 kDa from fermented milk were evaluated. Results indicated that the WSF from fermented milk with Lc-572 showed antithrombotic (IC50 = 0.049 mg/mL) and hypocholesterolemic (55% inhibition of micellar solubility of cholesterol and 27% bile acid binding capacity) activities. Meanwhile, fermented milk with Lc-571 showed mainly antithrombotic activity (IC50 = 0.045 mg/mL). On the other hand, fermented milk with Lc-600 presented mainly hypocholesterolemic activity (31.4% inhibition of micellar solubility of and 70% bile acid binding capacity). Moreover, biological activities were not lost after simulated gastrointestinal digestion conditions. Thus, fermented milk with these specific L. lactis strains show potential for the development of functional foods.

Ammonium formation and assimilation in P(SARK)∷IPT tobacco transgenic plants under low N.

Wild Type (WT) and transgenic tobacco plants expressing isopentenyltransferase (IPT), a gene encoding the enzyme regulating the rate-limiting step in cytokinins (CKs) synthesis, were grown under limited nitrogen (N) conditions. We analyzed nitrogen forms, nitrogen metabolism related-enzymes, amino acids and photorespiration related-enzymes in WT and P(SARK)∷IPT tobacco plants. Our results indicate that the WT plants subjected to N deficiency displayed reduced nitrate (NO3⁻) assimilation. However, an increase in the production of ammonium (NH4⁺), by the degradation of proteins and photorespiration led to an increase in the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle in WT plants. In these plants, the amounts of amino acids decreased with N deficiency, although the relative amounts of glutamate and glutamine increased with N deficiency. Although the transgenic plants expressing P(SARK)∷IPT and growing under suboptimal N conditions displayed a significant decline in the N forms in the leaf, they maintained the GS/GOGAT cycle at control levels. Our results suggest that, under N deficiency, CKs prevented the generation and assimilation of NH4⁺ by increasing such processes as photorespiration, protein degradation, the GS/GOGAT cycle, and the formation of glutamine.

Does iodine biofortification affect oxidative metabolism in lettuce plants?

Plants produce low levels of reactive oxygen species (ROS), which form part of basic cell chemical communication; however, different types of stress can lead to an overexpression of ROS that can damage macromolecules essential for plant growth and development. Iodine is vital to human health, and iodine biofortification programs help improve the human intake through plant consumption. This biofortification process has been shown to influence the antioxidant capacity of lettuce plants, suggesting that the oxidative metabolism of the plant may be affected. The results of this study demonstrate that the response to oxidative stress is variable and depends on the form of iodine applied. Application of iodide (I(-)) to lettuce plants produces a reduction in superoxide dismutase (SOD) activity and an increase in catalase (CAT) and L-galactono dehydrogenase enzyme activities and in the activity of antioxidant compounds such as ascorbate (AA) and glutathione. This did not prove a very effective approach since a dose of 80 µM produced a reduction in the biomass of the plants. For its part, application of iodate (IO (3) (-) ) produced an increase in the activities of SOD, ascorbate peroxidase, and CAT, the main enzymes involved in ROS detoxification; it also increased the concentration of AA and the regenerative activities of the Halliwell-Asada cycle. These data confirm the non-phytotoxicity of IO (3) (-) since there is no lipid peroxidation or biomass reduction. According to our results, the ability of IO (3) (-) to induce the antioxidant system indicates that application of this form of iodine may be an effective strategy to improve the response of plants to different types of stress.

Ammonia production and assimilation: its importance as a tolerance mechanism during moderate water deficit in tomato plants.

Nitrate assimilation diminishes under water stress. This can augment the photorespiratory rate as a protection mechanism, increasing the ammonium concentration, which must be rapidly assimilated. We therefore examined the effect of moderate water stress in photorespiration and N assimilation, as possible tolerance mechanisms in cherry tomato. Five cherry tomato cultivars with different degrees of water stress tolerance were submitted to two water treatments: well-watered (100% FC) and water stress (50% FC). In the susceptible cultivars, nitrate assimilation declined but without stimulating photorespiration. Zarina, a stress-tolerant cultivar, showed increased activity of the main enzymes involved in photorespiration, together with greater assimilation of nitrates and of the resulting ammonium. This translates as higher concentrations of N as well as amino acids and proteins. We characterize these mechanisms in the cv. Zarina (tolerant) as essential to water stress tolerance, acting on N metabolism as well as helping to maintain or augment biomass.

Cytokinin-dependent improvement in transgenic P(SARK)::IPT tobacco under nitrogen deficiency.

Wild-type (WT) and transgenic tobacco plants overexpressing isopentenyltransferase (IPT), a gene coding the rate-limiting step in cytokinin (CKs) synthesis, were grown under limited nitrogen (N) conditions to evaluate the role of CKs in NUE (N-use efficiency) and in different parameters that determine the quality of tobacco leaves. The results indicate that WT tobacco plants submitted to N deficiency show a decline in the leaf/root ratio, associated with a decrease in the NUE and in tobacco-leaf quality, defined by an increase in the quantity of nicotine. On the contrary, the transgenic plants submitted to N deficiency maintained the leaf/root ratio, presenting a higher NUE and greater quality of tobacco leaves than the WT plants, as the latter showed reduced nicotine and an increase in reducing sugars under severe N-deficiency conditions. Therefore, the overexpression of CKs under N deficiency could be a useful tool to improve tobacco cultivation, given that it could reduce N-fertilizer application and thereby provide economic savings and environmental benefits, maintaining yield and improving tobacco leaf quality.