Understanding Aß Peptide Binding to Lipid Membranes: A Biophysical Perspective.

Aß peptides are known to bind neural plasma membranes in a process leading to the deposit of Aß-enriched plaques. These extracellular structures are characteristic of Alzheimer's disease, the major cause of late-age dementia. The mechanisms of Aß plaque formation and deposition are far from being understood. A vast number of studies in the literature describe the efforts to analyze those mechanisms using a variety of tools. The present review focuses on biophysical studies mostly carried out with model membranes or with computational tools. This review starts by describing basic physical aspects of lipid phases and commonly used model membranes (monolayers and bilayers). This is followed by a discussion of the biophysical techniques applied to these systems, mainly but not exclusively Langmuir monolayers, isothermal calorimetry, density-gradient ultracentrifugation, and molecular dynamics. The Methodological Section is followed by the core of the review, which includes a summary of important results obtained with each technique. The last section is devoted to an overall reflection and an effort to understand Aß-bilayer binding. Concepts such as Aß peptide membrane binding, adsorption, and insertion are defined and differentiated. The roles of membrane lipid order, nanodomain formation, and electrostatic forces in Aß-membrane interaction are separately identified and discussed.

Vesicle-vesicle fusion promoted by the Atg8-family autophagy protein LC3C: relevance of the N-terminal region.

Among the MAP1LC3/LC3 subfamily of Atg8 proteins, LC3B and LC3C constitute the most and least studied members, respectively, LC3B being generally considered as an autophagosomal marker and a canonical representative of the LC3 subfamily. In several recent studies, LC3C has emerged as an important modulator in various processes of cell homeostasis. Our own research data demonstrate that LC3C induces higher levels of tethering and of intervesicular lipid mixing than LC3B. LC3C contains a peculiar N-terminal region, different from the other Atg8-family protein members. Using a series of mutants, we have shown that the N-terminal region of LC3C is responsible for the enhanced vesicle tethering, membrane perturbation and vesicle-vesicle fusion activities of LC3C as compared to LC3B.Abbreviations: ATG: autophagy related; GABARAP: gamma-aminobutyric acid receptor associated protein; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PC: phosphatidyl choline; PE: phosphatidylethanolamine; PEmal: maleimide-derivatized PE; PtdIns: phosphatidylinositol.

The Influence of Lipid Electric Charge on the Binding of Aß(1-42) Amyloid Peptide to Bilayers in the Liquid-Ordered State.

The amyloidogenic Aß peptides are widely considered as a pathogenic agent in Alzheimer's disease. Aß(1-42) would form aggregates of amyloid fibrils on the neuron plasma membranes, thus perturbing neuronal functionality. Conflicting data are available on the influence of bilayer order on Aß(1-42) binding to membranes. In the present study, a biophysical approach was used in which isothermal calorimetry and surface pressure measurements were applied to explore the interaction of Aß(1-42) in either monomeric, oligomeric, or fibrillar form with model membranes (bilayers or monolayers) in the liquid-ordered state that were either electrically neutral or negatively charged. In the latter case, this contained phosphatidic acid, cardiolipin, or ganglioside. The calorimetric studies showed that Aß(1-42) fibrils, oligomers, and monomers could bind and/or be inserted into bilayers, irrespective of electric charge, in the liquid-ordered state, except that monomers could not interact with electrically neutral bilayers. The monolayer studies in the Langmuir balance demonstrated that Aß(1-42) aggregation hindered peptide insertion into the monolayer, hindered insertion in the decreasing order of monomer > oligomer > fibril, and that lipid composition did not cause large differences in insertion, apart from a slight facilitation of monomer and oligomer insertion by gangliosides.

The N-terminal region of the ATG8 autophagy protein LC3C is essential for its membrane fusion properties.

Autophagy is a catabolic process in which a double-membrane organelle, the autophagosome (AP), engulfs cellular components that will be degraded in the lysosomes. ATG8 protein family members participate at various stages of AP formation. The present study compares the capacity to induce lipid-vesicle tethering and fusion of two ATG8 family members, LC3B and LC3C, with model membranes. LC3B is the most thoroughly studied ATG8 protein. It is generally considered as an autophagosomal marker and a canonical representative of the LC3 subfamily. LC3C is less studied, but recent data have reported its implication in various processes, crucial to cellular homeostasis. The results in this paper show that LC3C induces higher levels of tethering and of intervesicular lipid mixing than LC3B. As the N-terminus of LC3C is different from that of the other family members, various mutants of the N-terminal region of both LC3B and LC3C were designed, and their activities compared. It was concluded that the N-terminal region of LC3C was responsible for the enhanced vesicle tethering, membrane perturbation and vesicle-vesicle fusion activities of LC3C as compared to LC3B. The results suggest a specialized function of LC3C in the AP expansion process.

Grass pollen allergoids conjugated with mannan for subcutaneous and sublingual immunotherapy: a dose-finding study.

Background: Polymerized allergoids conjugated with mannan represent a novel approach of allergen immunotherapy targeting dendritic cells. In this study, we aimed to determine the optimal dose of mannan-allergoid conjugates derived from grass pollen (Phleum pratense and Dactylis glomerata) administered via either the subcutaneous or sublingual route. Methods: A randomized, double-blind, placebo-controlled trial with a double-dummy design was conducted, involving 162 participants across 12 centers in Spain. Subjects were randomly allocated to one of nine different treatment groups, each receiving either placebo or active treatment at doses of 500, 1,000, 3,000, or 5,000 mTU/mL over four months. Each participant received five subcutaneous (SC) doses of 0.5 mL each, every 30 days, and a daily sublingual (SL) dose of 0.2 mL. Participants who received active treatment through SC, received placebo through SL. Participants who received active treatment through SL, received placebo SC. One Group, as control, received bot SC and SL placebo. The primary efficacy outcome was the improvement in titrated nasal provocation tests (NPT) at the end of the study compared to baseline. Secondary outcomes included specific antibody (IgG4, IgE) and cellular (IL-10 producing and regulatory T cell) responses. All adverse events and side reactions were recorded and assessed. Results: Post-treatment, the active groups showed improvements in NPT ranging from 33% to 53%, with the highest doses showing the greatest improvements regardless of the administration route. In comparison, the placebo group showed a 12% improvement. Significant differences over placebo were observed at doses of 3,000 mTU/mL (p=0.049 for SL, p=0.015 for SC) and 5,000 mTU/mL (p=0.011 for SL, p=0.015 for SC). A dose-dependent increase in IgG4 was observed following SC administration, and an increase in IL-10 producing cells for both routes of administration. No serious systemic or local adverse reactions were recorded, and no adrenaline was required. Conclusion: Grass pollen immunotherapy with mannan-allergoid conjugates was found to be safe and efficacious in achieving the primary outcome, whether administered via the subcutaneous or sublingual routes, at doses of 3,000 and 5,000 mTU/mL. Clinical trial registration: https://www.clinicaltrialsregister.eu/ctr-search (EudraCT), identifier 2014-005471-88; https://www.clinicaltrials.gov, identifier NCT02654223.

Noninvasive Detection of Neuroendocrine Prostate Cancer through Targeted Cell-free DNA Methylation.

Castration-resistant prostate cancer (CRPC) is a heterogeneous disease associated with phenotypic subtypes that drive therapy response and outcome differences. Histologic transformation to castration-resistant neuroendocrine prostate cancer (CRPC-NE) is associated with distinct epigenetic alterations, including changes in DNA methylation. The current diagnosis of CRPC-NE is challenging and relies on metastatic biopsy. We developed a targeted DNA methylation assay to detect CRPC-NE using plasma cell-free DNA (cfDNA). The assay quantifies tumor content and provides a phenotype evidence score that captures diverse CRPC phenotypes, leveraging regions to inform transcriptional state. We tested the design in independent clinical cohorts (n = 222 plasma samples) and qualified it achieving an AUC > 0.93 for detecting pathology-confirmed CRPC-NE (n = 136). Methylation-defined cfDNA tumor content was associated with clinical outcomes in two prospective phase II clinical trials geared towards aggressive variant CRPC and CRPC-NE. These data support the application of targeted DNA methylation for CRPC-NE detection and patient stratification. SIGNIFICANCE: Neuroendocrine prostate cancer is an aggressive subtype of treatment-resistant prostate cancer. Early detection is important, but the diagnosis currently relies on metastatic biopsy. We describe the development and validation of a plasma cell-free DNA targeted methylation panel that can quantify tumor fraction and identify patients with neuroendocrine prostate cancer noninvasively. This article is featured in Selected Articles from This Issue, p. 384.

Presentaciones clínicas y diagnóstico de la infección por parvovirus humano B 19 / Clinical presentations and diagnosis of human parvovirus B 19

Human parvovirus B19 is associated with different clinical manifestations like infectious erythema, arthropathies, foetal hydropesia, transitory aplastic crisis and chronic anaemia. Our laboratory carries out differential diagnosis and develops different investigations, like the research on an epidemic outbreak affecting 21 individuals from a region with 1 400 inhabitants. The presence of specific IgM antibodies against parvovirus was positive in 90.5% and viremia was of 66.7%. Another investigation included 22 pregnant women, 17 presenting foetal hydropesia and 5 exanthemas. Five out of the 17 women with hydropesia (29.4%) and one out of the 5 with exanthema (20%) were positive for B19. Preliminarily we concluded that the percentage of patients positive for parvovirus in this population was similar to international data (27%). Preliminary work was carried out to study the seroprevalence in 154 samples that included two population groups, 115 indigenous individuals (49 Tobas and 66 Wichís) and 39 nonindigenous individuals (Criollos). Out of the 154 analysed sera, 94 (61%) were positive, with different distribution according to the ethnic group. This work is currently being continued in other regions. In Argentina the statistical data about parvovirus B19 are limited. The Instituto Nacional de Enfermedades Infecciosas (INEI) is involved in the diagnosis and research of this agent in order to offer an accurate diagnosis and epidemiological data that may contribute to the planning of public health activities

El parvovirus humano B19 se asocia con distintas manifestaciones clínicas como eritema infeccioso, artropatías, hidropesía fetal, crisis aplásicas transitorias y anemias crónicas. En el laboratorio se realiza el diagnóstico diferencial y se desarrollan diferentes investigaciones, como el brote exantemático ocurrido en una región de 1 400 habitantes que afectó a 21 personas. La presencia de anticuerpos IgM contra parvovirus fue del 90.5% y la viremia fue de un 66.7%. Otra investigación abarcó 22 embarazadas: 17 presentaban hidropesía fetal, y 5, exantema. Cinco de las 17 mujeres (29.4%) con hidropesía y 1 de las 5 (20%) con exantema resultaron positivas para parvovirus. La conclusión preliminar fue que el porcentaje de pacientes que resultaron positivas para este agente viral, en esta población, fue semejante a los datos internacionales (27%). Se realizaron estudios preliminares de seroprevalencia en 154 muestras de dos grupos poblacionales: a) 115 individuos aborígenes (49 tobas y 66 wichís) y b) 39 individuos no borígenes (criollos). De los 154 sueros analizados 94 (61%) resultaron positivos y su distribución fue diferente según la etnia. Se continúa con el estudio en otras regiones. En la Argentina los datos estadísticos acerca de parvovirus B19 son escasos, en el Instituto Nacional de Enfermedades Infecciosas (INEI) se realiza el diagnóstico de este agente y se mantienen líneas de investigación en el tema con el objetivo de brindar un diagnóstico de certeza y aportar los datos epidemiológicos que contribuyan a la planificación de las actividades de salud públicas

Psicólogos en instituciones educativas: representaciones del rol y modalidades de intervención / Psychologists in educational institutions: role representations and intervention modalities

El trabajo presenta líneas de indagación, y primeros resultados del Proyecto de Investigación "Rol del Psicólogo en la Institución Educativa. Prácticas y Saberes. Evaluación e Intervención. La representación de las causas de los problemas de aprendizaje", con sede en la Facultad de Psicología de la UBA. Se trabaja con los datos extraídos de una muestra de entrevistas a psicólogos, directivos y docentes que trabajan en instituciones educativas de la Ciudad de Buenos Aires y el conurbano. Las variables son: funciones asignadas al psicólogo por los tres actores, principales problemas educativos detectados, causas de los problemas y herramientas utilizadas . Se interrelacionan estos datos con los extraídos de los cuestionarios administrados a los alumnos de "Psicología Educacional Cátedra II", al inicio y al cierre del dictado de la asignatura, Primer Cuatrimestre del Año 2000, en los que se indagan representaciones que éstos poseen sobre el psicólogo que trabaja en el campo.

The work presents research lines, and the first results of the Project of Investigation "Role of the Psychologist in the Educational Institution. Practice and Knowledge. Evaluation and Intervention. The representation of the causes of learning problems", which is developed in the University School of Psychology. We analyse data obtained from a sample of interviews to psychologists, headmasters and teachers that work in educational institutions of the City of Buenos Aires and surroundings. The variables are: functions assigned to the psychologist by the three actors, main educational problems, causes of the problems, and the object of the psychologists´analyse and intervention. We also analyse the intersections with data obtained from the questionnaires administered to the students of "Educational Psychology" (Chair II), at the beginning and the end of the course, and the representations that the students have about the psychologists and their work in the field.

Eficacia del diazepam en la prevención de algunos efectos indeseables de la succinilcolina / Efficacy of diazepan for the preventions of some indesivable effects of succinilcoline

Con el propósito de comparar el efecto del Diazepam con el de Pancuronio y D-Tubocurarina en la prevención de los efectos indeseables de la Succinilcolina, se estudiaron 33 pacientes anestésicos tratados con estas drogas en quienes se determinaron: la intensidad de las fasciculaciones musculares, la calidad y duración del bloqueo neuromuscular, el dolor muscular postoperatorio, y los niveles séricos de Potasio y Creatinfosfoquinasa antes y después de la administración de Succinilcolina. A diferencia de lo sostenido por algunos autores, se encontró que el Diazepam no resultó eficaz en prevenir estos efectos y por lo tanto, no presenta ninguna ventaja comparado con el Pancuronio y la D-Tubocurarina

Psicólogos en instituciones educativas: representaciones del rol y modalidades de intervención / Psychologists in educational institutions: representations of the role and methods of intervention

El trabajo presenta líneas de indagación, y primeros resultados del Proyecto de Investigación "Rol del Psicólogo en la Institución Educativa. Prácticas y Saberes. Evaluación e Intervención. La representación de las causas de los problemas de aprendizaje", con sede en la Facultad de Psicología de la UBA. Se trabaja con los datos extraídos de una muestra de entrevistas a psicólogos, directivos y docentes que trabajan en instituciones educativas de la Ciudad de Buenos Aires y el conurbano. Las variables son: funciones asignadas al psicólogo por los tres actores, principales problemas educativos detectados, causas de los problemas y herramientas utilizadas . Se interrelacionan estos datos con los extraídos de los cuestionarios administrados a los alumnos de "Psicología Educacional Cátedra II", al inicio y al cierre del dictado de la asignatura, Primer Cuatrimestre del Año 2000, en los que se indagan representaciones que éstos poseen sobre el psicólogo que trabaja en el campo...

Cirugía en el paciente con riñón transplantado y funcionante / Surgery in patients with stable renal allograft function

Se analizan 107 intervenciones quirúrgicas realizadas a 98 pacientes con riñones trasplantados funcionantes, lo que representa el 35,5% de 276 enfermos que recibieron riñones operatoriamente. Las intervenciones no involucran al riñón trasplantado ni a sus vasos arteriales o venosos. Son 8 ginecológicas, 24 urológicas, 6 torácicas, 8 oftalmológicas, 2 de neurocirugía, 37 cirugía general, 17 ortopédicas y 5 de cirugía plástica. Fueron urgentes 35 (32,7%) y electivas 72 (67,3%). Se operaron 26 pacientes cuya indicación fue la infección. La mortalidad operatoria global fue del 15,3% y resultó mucho más elevada en las operaciones urgentes (34,28%) que las electivas (4,16%).

Prevalencia de HCV y HBV en pacientes pediatricos hemodializados: estudio multicentrico / HCV and HBV prevalence in hemodialyzed pediatric patients: multicenter study

Los pacientes Hd constituyen una población de riesgo para la infección por los virus de las hepatitis B y C. El objetivo de este trabajo fue evaluar la prevalencia de la infección por HCV y HBV en un corte de una población de niños hemodializados. Se estudiaron 61 pacientes pediátricos en hemodiálisis, 12 de los cuales eran Tx, con edades comprendidas entre 2 y 20 años (media: 12,9), 23 varones y 38 mujeres. Se determinaron los anticuerps anti-HCV IgG por enzimoinmunoensayo (EIE) (Abbott 2 generación) y como método confirmatorio se utilizó inmunoblotting de péptidos sintéticos linearizados (LIA-TEK) (Organon). La detección de los marcadores para HBV fue por EIE y el nivel de actividad de las transaminasas se determinó por método cintético. El 19,7 por ciento de los niños estudiados fueron HCV positivos y el 29,5 por ciento fueron HBV positivos, de los cuales el 38,9 por ciento fueron HBsAg positivos el 50 por ciento Anti-HBs positivos. La infección por HCV y HBV se vió incrementada en relación al número de transfusiones y al tiempo de inclusión en Hd. La elevación de nivel de actividad de las transaminasas no fue un buen índice de infección para HBV y HCV en estos pacientes.