Cracking the membrane lipid code.

Why has nature acquired such a huge lipid repertoire? Although it would be theoretically possible to make a lipid bilayer fulfilling barrier functions with only one glycerophospholipid, there are diverse and numerous different lipid species. Lipids are heterogeneously distributed across the evolutionary tree with lipidomes evolving in parallel to organismal complexity. Moreover, lipids are different between organs and tissues and even within the same cell, different organelles have characteristic lipid signatures. At the molecular level, membranes are asymmetric and laterally heterogeneous. This lipid asymmetry at different scales indicates that these molecules may play very specific molecular functions in biology. Some of these roles have been recently uncovered: lipids have been shown to be essential in processes such as hypoxia and ferroptosis or in protein sorting and trafficking but many of them remain still unknown. In this review we will discuss the importance of understanding lipid diversity in biology across scales and we will share a toolbox with some of the emerging technologies that are helping us to uncover new lipid molecular functions in cell biology and, step by step, crack the membrane lipid code.

Multitracer PET/CT with [18F]Fluorodeoxiglucose and [18F]Fluorocholine in the Initial Staging of Multiple Myeloma Patients Applying the IMPeTus Criteria: A Pilot Study.

Initial staging of patients diagnosed with multiple myeloma (MM) can lead to negative results using conventional diagnostic imaging workup, including [18F]Fluorodesoxiglucose ([18F]FDG) PET/CT. The aim of this prospective pilot study was to evaluate the diagnostic efficacy of [18F]Fluorocholine ([18F]FCH) PET/CT in the initial staging of MM patients who were candidates for autologous bone marrow transplant. Materials and Methods: The inclusion criteria of our study were: (a) patients diagnosed with MM; (b) candidates for autologous bone marrow transplant (AT); and (c) studied with [18F]FCH PET/CT and [18F]FDG PET/CT for initial staging less than 4 weeks apart. Imaging analysis included the presence of: bone marrow infiltration, focal bone lesions, and para-medullary or extra-medullary disease, according to the proposed IMPeTus criteria. The analysis was performed per lesion, per patient, and per location. Results: The study population included ten patients. Globally, [18F]FCH PET/CT showed bone marrow uptake in all the patients and visualised 16 more focal lesions than [18F]FDG PET/CT. One patient presented a plasmacytoma, detected by both tracers. Extra-medullary and para-medullary disease was identified with different degrees of uptake by both tracers. In summary, [18F]FCH PET seemed to be superior to [18F]FDG PET/CT in detecting focal bone lesions. SUVmax values were slightly higher in [18F]FCH PET/CT than in [18F]FDG PET/CT. Conclusions: Taking into account the small study population, according to our results, [18F]FCH PET/CT could be a useful tool for staging MM patients.

[18F]FDG PET/CT in the Evaluation of Melanoma Patients Treated with Immunotherapy.

Immunotherapy is based on manipulation of the immune system in order to act against tumour cells, with growing evidence especially in melanoma patients. The challenges faced by this new therapeutic tool are (i) finding valid evaluation criteria for response assessment; (ii) knowing and distinguishing between "atypical" response patterns; (iii) using PET biomarkers as predictive and response evaluation parameters and (iv) diagnosis and management of immunorelated adverse effects. This review is focused on melanoma patients analysing (a) the role of [18F]FDG PET/CT in the mentioned challenges; (b) the evidence of its efficacy. For this purpose, we performed a review of the literature, including original and review articles. In summary, although there are no clearly established or globally accepted criteria, modified response criteria are potentially appropriate for evaluation of immunotherapy benefit. In this context, [18F]FDG PET/CT biomarkers appear to be promising parameters in prediction and assessment of response to immunotherapy. Moreover, immunorelated adverse effects are recognized as predictors of early response to immunotherapy and may be associated with better prognosis and clinical benefit.

Ultrastructure of COPII vesicle formation in yeast characterized by correlative light and electron microscopy.

Traffic of proteins out of the endoplasmic reticulum (ER) is driven by the COPII coat, a layered protein scaffold that mediates the capture of cargo proteins and the remodeling of the ER membrane into spherical vesicular carriers. Although the components of this machinery have been genetically defined, and the mechanisms of coat assembly extensively explored in vitro, understanding the physical mechanisms of membrane remodeling in cells remains a challenge. Here we use correlative light and electron microscopy (CLEM) to visualize the nanoscale ultrastructure of membrane remodeling at ER exit sites (ERES) in yeast cells. Using various COPII mutants, we have determined the broad contribution that each layer of the coat makes to membrane remodeling. Our data suggest that inner coat components define the radius of curvature, whereas outer coat components facilitate membrane fission. The organization of the coat in conjunction with membrane biophysical properties determines the ultrastructure of vesicles and thus the efficiency of protein transport.

Cargo crowding contributes to sorting stringency in COPII vesicles.

Accurate maintenance of organelle identity in the secretory pathway relies on retention and retrieval of resident proteins. In the endoplasmic reticulum (ER), secretory proteins are packaged into COPII vesicles that largely exclude ER residents and misfolded proteins by mechanisms that remain unresolved. Here we combined biochemistry and genetics with correlative light and electron microscopy (CLEM) to explore how selectivity is achieved. Our data suggest that vesicle occupancy contributes to ER retention: in the absence of abundant cargo, nonspecific bulk flow increases. We demonstrate that ER leakage is influenced by vesicle size and cargo occupancy: overexpressing an inert cargo protein or reducing vesicle size restores sorting stringency. We propose that cargo recruitment into vesicles creates a crowded lumen that drives selectivity. Retention of ER residents thus derives in part from the biophysical process of cargo enrichment into a constrained spherical membrane-bound carrier.

Lysophospholipids Facilitate COPII Vesicle Formation.

Coat protein complex II (COPII) proteins form vesicles from the endoplasmic reticulum to export cargo molecules to the Golgi apparatus. Among the many proteins involved in this process, Sec12 is a key regulator, functioning as the guanosine diphosphate (GDP) exchange factor for Sar1p, the small guanosine triphosphatase (GTPase) that initiates COPII assembly. Here we show that overexpression of phospholipase B3 in the thermosensitive sec12-4 mutant partially restores growth and protein transport at non-permissive temperatures. Lipidomics analyses of these cells show a higher content of lysophosphatidylinositol (lysoPI), consistent with the lipid specificity of PLB3. Furthermore, we show that lysoPI is specifically enriched in COPII vesicles isolated from in vitro budding assays. As these results suggested that lysophospholipids could facilitate budding under conditions of defective COPII coat dynamics, we reconstituted COPII binding onto giant liposomes with purified proteins and showed that lysoPI decreases membrane rigidity and enhances COPII recruitment to liposomes. Our results support a mechanical facilitation of COPII budding by lysophospholipids.

Multi-centre audit of VMAT planning and pre-treatment verification.

BACKGROUND AND PURPOSE: We performed a multi-centre intercomparison of VMAT dose planning and pre-treatment verification. The aims were to analyse the dose plans in terms of dosimetric quality and deliverability, and to validate whether in-house pre-treatment verification results agreed with those of an external audit. MATERIALS AND METHODS: The nine participating centres encompassed different machines, equipment, and methodologies. Two mock cases (prostate and head and neck) were planned using one and two arcs. A plan quality index was defined to compare the plans and different complexity indices were calculated to check their deliverability. We compared gamma index pass rates using the centre's equipment and methodology to those of an external audit (global 3D gamma, absolute dose differences, 10% of maximum dose threshold). Log-file analysis was performed to look for delivery errors. RESULTS: All centres fulfilled the dosimetric goals but plan quality and delivery complexity were heterogeneous and uncorrelated, depending on the manufacturer and the planner's methodology. Pre-treatment verifications results were within tolerance in all cases for gamma 3%-3mm evaluation. Nevertheless, differences between the external audit and in-house measurements arose due to different equipment or methodology, especially for 2%-2mm criteria with differences up to 20%. No correlation was found between complexity indices and verification results amongst centres. CONCLUSIONS: All plans fulfilled dosimetric constraints, but plan quality and complexity did not correlate and were strongly dependent on the planner and the vendor. In-house measurements cannot completely replace external audits for credentialing.

Hormones and silk. Gay men in the Spanish film comedies of the transition to democracy (1976-1981).

This article studies the representation of gay men in Spanish comedies of the 1970s. It analyzes how cinema used the stereotypical image of gay men projected by the dictatorship and how, once it ended, this image endured in the comedy genre. It introduces film theories on the construction of humor taken from relevant authors, such as Jordan, Charney, Voitylla, and Petri. Afterward, it focuses on the works of Ozores as a filmmaker who encapsulates the main characteristics of the so-called comedia de mariquitas (sissy comedy). It analyzes how the construction of humor was based on the Francoist conception of gay men, and questions why the figure of the gay man was so effective in the production of comedy. Finally, this article refers to Dyer's theories around stereotyping, and develops them to study the Spanish context.

Protein O-mannosyltransferases participate in ER protein quality control.

In eukaryotic cells, proteins enter the secretory pathway at the endoplasmic reticulum (ER) as linear polypeptides and fold after translocation across or insertion into the membrane. If correct folding fails, many proteins are O-mannosylated inside the ER by an O-mannosyltransferase, the Pmt1p-Pmt2p complex. The consequences of this modification are controversial and the cellular role of the Pmt1p-Pmt2p complex in this respect is unclear. Here, we have identified the binding partners of yeast Pmt1p and Pmt2p. These include ER chaperones involved in oxidative protein folding; the Hrd1p complex, which is involved in ER-associated protein degradation (ERAD); and the p24 protein complex involved in ER export. The results suggest that the Pmt1p-Pmt2p complex participates in these processes. We tested this assumption in a functional assay and found that whereas the Pmt1p-Pmt2p complex promotes fast ER export of the GPI-anchored protein Gas1p, it retains the misfolded version Gas1*p and targets it to the Hrd1p complex for subsequent degradation. Our results reveal previously unknown cellular roles of the Pmt1p-Pmt2p complex in connection with the ERAD machinery and show its participation in ER protein quality control.

Trastorno por déficit de atención/hiperactividad: ¿un patrón evolutivo? / Attention deficit disorder and hyperactivity: a pattern of evolution?

Introducción. Cuando la secuencia de un gen en la población general supera el 1% no se considera una mutación aleatoria, sino una mutación que se ha seleccionado positivamente a lo largo de la evolución. La alta prevalencia del trastorno por déficit de atención/hiperactividad (TDAH), de un 5-10%, y su asociación con el alelo siete de repetición de DRD4, que se ha seleccionado de manera positiva en la evolución, plantean la posibilidad de que el TDAH incrementa la aptitud reproductiva del individuo o el grupo. Una de las principales características del TDAH es su diversidad, y es un hecho bienreconocido que la diversidad confiere muchos beneficios a una población (p. ej., la inmunidad). Desarrollo. En este artículo se comentan los diferentes estudios que apoyan esta hipótesis y, además, ofrece explicaciones adicionales sobre la prevalencia, distribución por edad y sexo, distribución de la gravedad y las propias características de la heterogeneidad del TDAH. Conclusión. Es posible que la presencia de combinaciones de genes alteradas, como ocurre en el TDAH, puede llevar beneficios concretos para la sociedad, aunque sean perjudiciales para el individuo (AU)

Introduction. When the frequency of a gene in the general population exceeds 1%, is not considered a random mutation but a mutation that has been positively selected during evolution. The high prevalence of attention deficit/hyperactivity disorder (ADHD) from 5-10% and its association with the seven-repeat allele of DRD4, which is positively selected in evolution, raising the possibility that ADHD increases the reproductive fitness of the individual and/or group. One of the main characteristics of ADHD is its diversity and is a well recognized fact that diversity confers many benefits to a population (eg. immunity). Development. This article discusses the various studies that support this hypothesis and offers further explanations on the prevalence, age distribution and sex distribution of the severity and heterogeneity of ADHD. Conclusion. It is possible that the presence of altered gene combinations, as in ADHD, can bring concrete benefits to society but are detrimental to the individual (AU)

El análisis modal de fallos y efectos (AMFE) ayuda a aumentar la seguridad en radioterapia / No disponible

Objetivos: A raíz de una incidencia de sobredosis detectada en el servicio de radioterapia, se puso en marcha un proyecto de análisis y eliminación de riesgos para aumentar la seguridad de los pacientes.Material y método: Se aplicó el análisis modal de fallos y efectos (AMFE), un instrumento analítico aplicado en varios hospitales de Estados Unidos. Como exige la metodología, se cuantificaron los riesgos de cada modo de fallo en una escala de 1:1.000 utilizando el índice NPR (número de priorización del riesgo). En una primera fase de mejora, se definió el nivel de actuación como NPR > 100. Se detectaron varios riesgos en los protocolos actuales y se eliminaron todos ellos mediante redefinición de circuitos, controles y verificaciones adicionales, listas de comprobación y auditorias internas, entre otros. Posteriormente, se introdujo un sistema de gestión de la calidad según ISO9001, se definió una serie de indicadores y la dirección se implicó realizando revisiones mensuales de los resultados. Resultados: Se implantaron 100 acciones de mejora. El índice de riesgo calculado después de haber tomado las acciones bajó significativamente y aumentó la seguridad. Las mejoras realizadas aseguran el mantenimiento del grado de seguridad logrado. Conclusiones: La experiencia muestra que se puede identificar objetivamente los riesgos de cada paso que damos y destinar los escasos recursos de que disponemos a los procesos o actividades donde el riesgo es mayor, mediante mejoras metodológicas de nuestros protocolos de trabajo

Objectives: As a result of an adverse event detected at the Radiotherapy Treatment Unit, a safety improvement project was undertaken to analyze and eliminate risks and thus increase patient safety. Material and method: Failure Mode and Effects Analysis (FMEA), ananalytical tool used in many US hospitals, was applied. As required by FMEA, risks of potential failure modes were quantified on a scale of 1 to 1000, using the Risk Priority Number (RPN). In the first improvement phase, an RPN value greater than 100 was consideredto be the limit above which corrective actions should be taken. Several potential failure modes were detected in existing treatment protocols and all the causes of potential failure modes were eliminatedthrough corrective actions that included redefinition of treatment protocols, the creation of new records for existing controls and the addition of new controls, checklists, and internal audits, amongother measures. Subsequently, a quality management system based on ISO9001 was introduced. Process indicators were defined to measure treatment quality, and the results were analyzed on a monthly basis with top management participation.Results: A total of 100 improvement actions were taken. The RPN values calculated after the implementation of the actions were significantly lower, increasing patient safety. The actions taken ensure the maintenance of the achieved safety levels. Conclusions: The experience shows that the risks present in all steps taken can be objectively identified. Through improved procedures, the limited resources available can be allocated to those processes or activities that pose maximum risk