pH-dependent Stability and Membrane Interaction of the Pore-forming Domain of Colicin A*

Thermal stability of the pore-forming domain of colicin A was studied by high sensitivity differential scanning calorimetry and circular dichroism spectroscopy. In the pH range between 8 and 5, the thermal denaturation of the protein in solution occurs at 66-69 degrees C and is characterized by the calorimetric enthalpy of approximately 90 kcal/M. At pH below 5, there is a rapid pH-dependent destabilization of the pore-forming domain resulting in the lowering of the midpoint denaturation temperature and a decrease in the calorimetric enthalpy of denaturation. Circular dichroism spectra in the near and far ultraviolet show that the thermotropic transition is associated with collapse of the native tertiary structure of the pore-forming domain, although a large proportion of the helical secondary structure remains preserved. The present data indicate some similarity also between acid-induced and temperature-induced denaturation of the pore-forming domain of colicin A. Association of the pore-forming domain with phospholipid vesicles of dioleoylphosphatidylglycerol results in total disappearance of the calorimetric transition, even at pH values as high as 7. Since lipid binding also induces collapse of the near ultraviolet circular dichroism spectrum, these data indicate that interaction with the membrane facilitates a conformational change within the pore-forming domain to a looser (denaturated-like) state. These findings are discussed in relation to the recent model (van der Goot, F. G., Gonzalez-Manas, J. M., Lakey, J. H., Pattus, F. (1991) Nature 354, 408-410) which postulates that a flexible "molten globule" state is an intermediate on the pathway to membrane insertion of colicin A

Functional characterization of Val60, a key residue involved in the membrane-oligomerization of fragaceatoxin C, an actinoporin from Actinia fragacea

AbstractActinoporins are pore-forming toxins produced by different sea anemones that self-assemble within the membranes of their target cells and compromise their function as a permeability barrier. The recently published three-dimensional structures of two oligomeric complexes formed by fragaceatoxin C point to Val60 as a key residue involved in the oligomerization of the functional pore.To gain insight into the mechanism of toxin oligomerization, different point mutations have been introduced at this position. Functional characterization of the muteins suggests that Val60 represents a hot-spot where the introduction of mutations hinders protein assembly and reduces the overall affinity for membranes

The Isolation of new pore-forming toxins from the sea anemone actinia fragacea provides insights into the mechanisms of actinoporin evolution

Random mutations and selective pressure drive protein adaptation to the changing demands of the environment. As a consequence, nature favors the evolution of protein diversity. A group of proteins subject to exceptional environmental stress and known for their widespread diversity are the pore-forming hemolytic proteins from sea anemones, known as actinoporins. In this study, we identified and isolated new isoforms of actinoporins from the sea anemone Actinia fragacea (fragaceatoxins). We characterized their hemolytic activity, examined their stability and structure, and performed a comparative analysis of their primary sequence. Sequence alignment reveals that most of the variability among actinoporins is associated with non-functional residues. The differences in the thermal behavior among fragaceatoxins suggest that these variability sites contribute to changes in protein stability. In addition, the protein-protein interaction region showed a very high degree of identity (92%) within fragaceatoxins, but only 25% among all actinoporins examined, suggesting some degree of specificity at the species level. Our findings support the mechanism of evolutionary adaptation in actinoporins and reflect common pathways conducive toprotein variability.Fil: Morante, Koldo. University of Tokyo; Japón. Universidad Politécnica de Valencia; España. Universidad del País Vasco; EspañaFil: Bellomio, Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Politécnica de Valencia; España. Universidad del País Vasco; EspañaFil: Vergara, Ana Rosa. Universidad Politécnica de Valencia; EspañaFil: González Mañas, Juan Manuel. Universidad del País Vasco; EspañaFil: Tsumoto, Kouhei. University of Tokyo; JapónFil: Caaveiro, José M. M.. University of Tokyo; Japón. Kyushu University; Japó

Usefulness of bone turnover markers as predictors of mortality risk, disease progression and skeletal-related events appearance in patients with prostate cancer with bone metastases following treatment with zoledronic acid: TUGAMO study

Owing to the limited validity of clinical data on the treatment of prostate cancer (PCa) and bone metastases, biochemical markers are a promising tool for predicting survival, disease progression and skeletal-related events (SREs) in these patients. The aim of this study was to evaluate the predictive capacity of biochemical markers of bone turnover for mortality risk, disease progression and SREs in patients with PCa and bone metastases undergoing treatment with zoledronic acid (ZA). Methods: This was an observational, prospective and multicenter study in which ninety-eight patients were included. Patients were treated with ZA (4mg every 4 weeks for 18 months). Data were collected at baseline and 3, 6, 9, 12, 15 and 18 months after the beginning of treatment. Serum levels of bone alkaline phosphtase (BALP), aminoterminal propeptide of procollagen type I (P1NP) and beta-isomer of carboxiterminal telopeptide of collagen I (b-CTX) were analysed at all points in the study. Data on disease progression, SREs development and survival were recorded. Results: Cox regression models with clinical data and bone markers showed that the levels of the three markers studied were predictive of survival time, with b-CTX being especially powerful, in which a lack of normalisation in visit 1 (3 months after the beginning of treatment) showed a 6.3-times more risk for death than in normalised patients. Levels of these markers were also predictive for SREs, although in this case BALP and P1NP proved to be better predictors. We did not find any relationship between bone markers and disease progression. Conclusion: In patients with PCa and bone metastases treated with ZA, b-CTX and P1NP can be considered suitable predictors for mortality risk, while BALP and P1NP are appropriate for SREs. The levels of these biomarkers 3 months after the beginning of treatment are especially importantThis study was supported by Novartis Oncology Spai

Gamificación en Iberoamérica. Experiencias desde la comunicación y la educación

La presente obra capitular es el resultado de las investigaciones sobre las aplicaciones de la gamificación en contextos múltiples, emergentes provenientes de las comunicaciones presentadas en el Simposio 06 del III Congreso Internacional Comunicación y Pensamiento (Sevilla, España), así como de aquellas presentadas por los miembros del Gamelab UPS, del Proyecto I+D+i Coordinado “Competencias mediáticas de la ciudadanía en medios digitales emergentes (smartphones y tablets): Prácticas innovadoras y estrategias educomunicativas en contextos múltiples” (EDU2015-64015-C3-1-R) (MINECO/FEDER), de la “Red de Educación Mediática” del Programa Estatal de Investigación Científica-Técnica de Excelencia, Subprograma Estatal de Generación de Conocimiento (EDU2016-81772-REDT), financiados por el Fondo Europeo de Desarrollo Regional (FEDER) y Ministerio de Economía y Competitividad de España. En este sentido se busca construir, desde una mirada dual desde Europa y América Latina el primer libro iberoamericano de gamificación, avalado por el Gamelab de la Universidad Politécnica Salesiana (Ecuador), el Proyecto I+D+i EDU2015-64015-C3-1-R, la Red Interuniversitaria Euroamericana de Investigación sobre Competencias Mediáticas para la Ciudadanía (Alfamed), el Laboratorio de Estudios en Comunicación (Ladecom) y el Grupo de Investigación Ágora (PAI-HUM-648) de la Universidad de Huelva (España) y el Grupo de Investigación Estructura, Historia y Contenidos de la Comunicación GREHCCO

ARIA 2016 : Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma and rhinitis and (3) to develop guidelines with all stakeholders that could be used globally for all countries and populations. ARIA-disseminated and implemented in over 70 countries globally-is now focusing on the implementation of emerging technologies for individualized and predictive medicine. MASK [MACVIA (Contre les Maladies Chroniques pour un Vieillissement Actif)-ARIA Sentinel NetworK] uses mobile technology to develop care pathways for the management of rhinitis and asthma by a multi-disciplinary group and by patients themselves. An app (Android and iOS) is available in 20 countries and 15 languages. It uses a visual analogue scale to assess symptom control and work productivity as well as a clinical decision support system. It is associated with an inter-operable tablet for physicians and other health care professionals. The scaling up strategy uses the recommendations of the European Innovation Partnership on Active and Healthy Ageing. The aim of the novel ARIA approach is to provide an active and healthy life to rhinitis sufferers, whatever their age, sex or socio-economic status, in order to reduce health and social inequalities incurred by the disease.Peer reviewe

Correlation between work impairment, scores of rhinitis severity and asthma using the MASK-air (R) App

Background In allergic rhinitis, a relevant outcome providing information on the effectiveness of interventions is needed. In MASK-air (Mobile Airways Sentinel Network), a visual analogue scale (VAS) for work is used as a relevant outcome. This study aimed to assess the performance of the work VAS work by comparing VAS work with other VAS measurements and symptom-medication scores obtained concurrently. Methods All consecutive MASK-air users in 23 countries from 1 June 2016 to 31 October 2018 were included (14 189 users; 205 904 days). Geolocalized users self-assessed daily symptom control using the touchscreen functionality on their smart phone to click on VAS scores (ranging from 0 to 100) for overall symptoms (global), nose, eyes, asthma and work. Two symptom-medication scores were used: the modified EAACI CSMS score and the MASK control score for rhinitis. To assess data quality, the intra-individual response variability (IRV) index was calculated. Results A strong correlation was observed between VAS work and other VAS. The highest levels for correlation with VAS work and variance explained in VAS work were found with VAS global, followed by VAS nose, eye and asthma. In comparison with VAS global, the mCSMS and MASK control score showed a lower correlation with VAS work. Results are unlikely to be explained by a low quality of data arising from repeated VAS measures. Conclusions VAS work correlates with other outcomes (VAS global, nose, eye and asthma) but less well with a symptom-medication score. VAS work should be considered as a potentially useful AR outcome in intervention studies.Peer reviewe

Binding of Triton X-100 to bovine serum albumin as studied by surface tension measurements

A previously published computerized drop-weight technique for surface tension measurements, not involving the use of radioactively labelled compounds, has been applied to the study of detergent binding to proteins. The procedure is based on the observation that the protein-surfactant complex is no longer surface-active. As an example, the binding of Triton X-100 to bovine serum albumin has been studied, and the results were found to be in good agreement with those obtained through established but less convenient methods. Our procedure should be useful for measurements of detergent binding to biomembranes. © 1991.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Kinetics of purple membrane dark-adaptation in the presence of Triton X-100

The kinetics of purple membrane dark adaptation were studied at pH 5 and 7, in the presence and absence of the nonionic detergent Triton X-100. The effect of both sublytic and lytic surfactant concentrations has been considered. Our results show that: (a) dark adaptation is faster at pH 5 than at pH 7, (b) dark adaptation is slower, and of smaller amplitude, in the presence than in the absence of Triton X-100. The data may be interpreted in terms of a simple first-order kinetic model, according to which light-dark adaptation would depend basically on the equilibrium between the 13-cis-and the all-trans-isomers. The experiments also suggest that at pH 5, but not at pH 7, solubilizing surfactant concentrations produce a considerable increase in the velocity of the dark adaptation reaction, perhaps through changes in the microenvironment of a protonable group. © 1990.SCOPUS: ar.jinfo:eu-repo/semantics/publishe