Conformational equilibria in o-anisic acid and its monohydrated complex: the prevalence of the trans-COOH form

The conformation of ortho-anisic acid and its monohydrated clusters generated in a supersonic jet has been studied by rotational spectroscopy to analyze the structural implications of ortho substitution. The dominant monomer species shows a trans-COOH arrangement stabilized by an intramolecular O–H...O hydrogen bond from the acid to the methoxy group. The spectra of two non-planar skeleton monomer forms with a cis-COOH arrangement have also been detected. A tunneling doublet has been observed for the most stable cis-COOH conformer. The periodic potential energy function for the COOH internal rotation connecting these cis forms has been estimated from the experimental data. For the first time a water complex with an acid in a trans-COOH configuration has been observed. This is more abundant than the other weak form observed for the complex, characterized by a cis-COOH arrangement. The observation of the rotational spectra of salicylic acid, methyl salicylate and methyl 2-methoxybenzoate, formed upon heating of ortho-anisic acid, gives additional interest in the chemistry of ortho substituted benzoic acids.Ministerio de economia, industria y competitividad CTQ2016-75253-

Pyridine–acetaldehyde, a molecular balance to explore the n→π*interaction

Producción CientíficaThe complex pyridine–acetaldehyde is formed through an n->pi* interaction and a C‐H∙∙∙O contact. The acetaldehyde methyl group internal rotation induces a phase‐locked intermolecular oscillation along the Bürgi‐Dunitz coordinate. Surprisingly, this sort of molecular balance extracts energy through the n->pi* interaction to reduce the size of the internal rotation barrier.Ministerio de economia, industria y competitividad CTQ2016-75253-

Competition Between Intra‐ and Intermolecular Hydrogen Bonding: o ‐Anisic Acid⋅⋅⋅Formic Acid Heterodimer

Producción CientíficaFour conformers of the heterodimer o-anisic acid – formic acid, formed in a supersonic expansion, have been probed by Fourier transform microwave spectroscopy. Two of these forms have the typical double intermolecular hydrogen bond cyclic structure. The other two show the o-anisic acid moiety bearing a trans-COOH arrangement supported by an intramolecular O-H··O bond to the neighbour methoxy group. In these conformers, formic acid interacts with o-anisic acid mainly through an intermolecular O-H···O hydrogen bond either to the O-H or to the C=O moieties, reinforced by other weak interactions. Surprisingly, the most abundant conformer in the supersonic expansion is the complex in which the o-anisic acid is in trans arrangement with the formic acid interacting with the O-H group. Such a trans-COOH arrangement in which the intramolecular hydrogen bond dominates over the usually observed double intermolecular hydrogen bond interaction has never been observed previously in an acid-acid dimer.Ministerio de economia, industria y competitividad CTQ2016-75253-

Conformational Landscape of m-Anisic Acid and Its Complexes with Formic Acid

Four conformers of m-anisic acid were observed in a supersonic expansion using Fourier transform microwave spectroscopy. These conformers correspond to different relative orientations of the acid and the methoxy groups and have their planar skeletons stabilized by resonance. When formic acid was present in the jet, the spectra of four m-anisic acid–formic acid heterodimer conformers were detected. The complexes are formed from the interaction of formic acid with each of the four observed conformers of m-anisic acid through the typical acid-acid sequential cycle with a double O-H···O=C hydrogen bond interaction in a pseudo eightmembered ring arrangement. The four heterodimer forms retain the same four m-anisic acid conformational geometries and the same relative abundances of the m-anisic acid monomeric forms in the supersonic expansion. This proves that a kinetic mechanism dominates the formation of complexes in the jet.Ministerio de economia, industria y competitividad CTQ2016-75253-

Hypermetabolic abdominal and cervical lymph nodes mimicking Hodgkin lymphoma relapse on FDG PET/CT after adenovirus-vectored COVID-19 vaccine

Vaccine-associated hypermetabolic lymphadenopathy (VAHL) has been reported as a common post-vaccination side effect, especially with mRNA-based COVID-19 vaccines. Most VAHL cases present normal or enlarged regional lymph nodes close to the injection site, usually with mild-moderate FDG (18 F-Fluorodeoxyglucose) uptake on FDG positron emission tomography (PET)/CT. Here, we describe the case of a 33-year-old woman with past history of Classic Hodgkin Lymphoma (CHL) who underwent follow-up FDG PET/CT 3 days (d) after the first dose of the adenovirus-vectored Oxford-AstraZeneca COVID-19 vaccine. FDG PET/CT showed unexpected small hypermetabolic cervical and abdominal lymph nodes in the same location as at the onset of the disease, suggesting radiological relapse. Considering temporal relationship and other cases of VAHL, a new image was performed 2 months later, which revealed decreased lymph nodes and normalization of FDG uptake. This case illustrates that the possibility of a false-positive should always be considered by physicians in this new context, even when hypermetabolic lymph nodes appear far from the vaccination site

"Nuclear medicine" session

En la sesión dedicada a la Medicina Nuclear (MN) se identificaron los cinco aspectos que se consideran más problemáticos en la protección radiológica en MN. Estos hacen referencia a: 1. Garantizar que la dosis administrada al paciente sea correcta; 2. Evitar en el trabajador la contaminación e irradiación de las extremidades superiores, cristalino y resto del cuerpo; 3. Asegurar la optimización de dosis en diagnóstico y tratamiento; 4. Promover la justificación de los exámenes en MN; 5. Prevenir incidentes y accidentes. Las soluciones aportadas a estos problemas fueron: 1. Implementar sistemas integrales de calidad y protocolos de control de calidad así como entrenar y capacitar adecuadamente a los trabajadores; 2. Mejorar la capacitación y formación del trabajador, uso sistemático de medios de protección y de protocolos de trabajo y adecuación de los procedimientos de trabajo; 3. Utilización de dosis estandarizadas en diagnóstico y planificar los tratamientos mediante dosimetría interna paciente específica; 4. Capacitación de médicos prescriptores y médicos nucleares y utilización de guías de adecuada solicitud de exámenes de MN; 5. Incorporación efectiva de sistemas de notificación de incidentes para su posterior análisis y aprendizaje mediante la utilización de técnicas de análisis de sucesos. Los indicadores propuestos para la adecuada valoración de los avances obtenidos en cada uno de los aspectos valorados fueron: 1. Número de centros con un Programa de garantía de calidad implementado y grado de cumplimiento del mismo en cada centro 2. Análisis de tendencias de los datos dosimétricos reportados 3. Cantidad de exámenes con protocolos de optimización de dosis o de estimación de la actividad paciente específico 4. Número de programas de estudio de pregrado de medicina que incluyen temas relacionados con Protección Radiológica y número de protocolos clínicos escritos con las indicaciones de cada estudio y porcentaje de exámenes que cumplen con estas guías. 5. Grado de implementación de de sistemas de notificación de incidentes de seguridad, grado de uso de herramientas de análisis pre dictivo y número de reuniones de evaluación de eventos Algunas de las soluciones propuestas son fácilmente incorporables a la práctica diaria. Sin embargo, otras requieren más tiempo y, sobre todo, acciones por grupos internacionales que trabajen conjuntamente para aportar soluciones concretas.In the session dedicated to Nuclear Medicine (NM) the five aspects considered the most problematic in radiation safety in NM were identified. These refer to: 1) Ensure the correct dose is delivered to the patient; 2) Avoid contamination and irradiation of the upper extremities, lens of the eyes and rest of the body; 3) Ensure the optimization of doses in diagnosis and treatment; 4 Promote the justification of the examinations in NM; and 5) Prevent incidents and accidents. The solutions provided to these problems were: 1) To implement quality management systems and quality control protocols as well as to educate and to train adequately the workers; 2) To improve the training and formation of workers, systematic use of personal pro tection equipment (PPE) and standard operation procedures (SOP’s) and adapta tion of working procedures; 3) To use standardized doses in diagnosis and planning each treatment by patient-spe cific dosimetry; 4) To train referring physicians and nuclear medicine physicians and to use referral guidelines for appropriate MN examinations; and 5) To incorporate effectively an incident reporting system for later analysis and learn ing through the use of event analysis techniques. The proposed indicators for an adequate evaluation of the obtained progress in each one of the assessed aspects were: 1) Number of centres with an implemented quality management system and its de gree of compliance in each centre; 2) Continuous trend analysis of dosimetric reports values; 3 Number of studies with dose optimisation protocols and/or patient-specific dosimetry; 4) Number of undergraduate medical programs that include subjects related to radia tion safety and number of written standard operation procedures with indications of each study and percentage of studies that comply with these guidelines; 5) Degree of implementation of security incident reporting systems, degree of use of predictive analysis tools and number of incident evaluation meetings; Some of the proposed solutions can be easily incorporated into daily practice. However, others require more time and, additionally, actions by international groups working together to provide concrete solutions.Na sessão dedicada à Medicina Nuclear (MN) consideraram-se cinco aspetos mais problemáticos na proteção contra as radiações em MN: 1. Garantia que a dose administrada ao paciente é correta; 2. Evitar a contaminação e irradiação das mãos, cristalino e resto do corpo do trablhador na área; 3. Assegurar a otimização das doses de diagnóstico e terapêutica; 4. Justificação de exames em MN; 5. A prevenção de incidentes e acidentes. Foram apresentadas as seguintes soluções para esses problemas: 1. Implementação de protocolos e regras de funcionamento bem definidas associadas a sistemas de controle de qualidade dos equipa mentos e à formação continua dos trabalhadores; 2. Melhorar a formação e treinamento dos trabalhadores na utilização sistemática dos meios de proteção e protocolos adequados aos procedimentos de trabalho; 3. Padronização das doses de diagnóstico e planificação das terapêuticas por dosimetria interna específica dos doentes; 4. Formação dos médicos prescritores e nucleares para utilização adequada de “Guidelines” para exames de MN; 5. Incorporação efetiva de sistemas de registo de incidentes e acidentes para posterior análise e melhoria das práticas utilizadas; Os indicadores propostos para avaliação dos avanços em cada um dos aspectos foram definidos como: 1. Número de centros com programa de garantia de qualidade utilizado e o grau de cumprimento em cada centro 2. A análise de tendência dos dados de dosimetria relatados. 3. Número de exames com os protocolos de otimização de dose ou estimativa da actividade específica para o paciente. 4. Número de currículos de graduação médica que incluam radioproteção, número de protocolos clínicos escritos com as indicações de cada estudo e porcentagem de testes que estejam em conformidade com estas diretrizes. 5. Grau de implementação da sistemas de informação sobre incidente, grau de utilização de ferramentas de análise preditiva e reuniões de avaliação número de eventos. Algumas das soluções propostas são fáceis de implementar na prática diária. Outras exigem mais tempo e, sobretudo, ações de grupos internacionais que trabalhem em conjunto para fornecer soluções concretas.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de FísicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias Atómicas Nucleares y Moleculares (CICANUM