Stability of metabolic tumor volume may enable radiotherapy dose painting in anal cancer.

PURPOSE: To evaluate the variability of the 18F-FDG-PET/CT-based metabolic tumor volume (MTV) in anal cancers during fractionated chemoradiotherapy (CRT), and assess the impact of this variability on dosimetric accuracy in MTV-targeted dose painting. METHODS: Eleven patients with anal squamous cell carcinoma who received fractionated chemoradiotherapy with curative intent were included. 18F-FDG PET/CT images were acquired at pre- and mid-treatment. Target volumes and organs at risk (OARs) were contoured manually on both image series. The MTV was generated from the PET images by thresholding. Treatment plans were retrospectively optimized for both image series using volumetric modulated arc therapy (VMAT). Standard plans prescribed 48.6 Gy, 54 Gy and 57.5 Gy in 27 fractions to elective regions, lymph node metastases and primary tumor, respectively. Dose painting plans included an extra dose level of 65 Gy to the MTV. Pre-treatment plans were transferred and re-calculated at mid-treatment basis. RESULTS: MTV decreased from pre- to mid-treatment in 10 of the 11 patients. On average, 71 % of MTVmid overlapped with MTVpre. The median and mean doses to the MTV were robust against anatomical changes, but the transferred dose painting plans had lower D98% values than the original and re-optimized plans. No major differences were found between standard and dose painting plans for OARs. CONCLUSIONS: Despite volumetric changes in the MTV, adequate dose coverage was observed in most dose painting plans. The findings indicate little or no need for adaptive dose painting at mid-treatment. Dose painting appears to be a safe treatment alternative with similar dose sparing of OARs.

Enseñanza histológica e histopatológica a través de microscopía virtual, una oportunidad en odontología / Virtual microscopy in histological and histopathological teaching, an opportunity in dentistry

RESUMEN La microscopía virtual (MV) está siendo ampliamente implementada en educación y podría llevar a reemplazar a la microscopía óptica (MO). Objetivo: Proporcionar una revisión de la literatura a partir de las preguntas ¿Cuál es la percepción de académicos y estudiantes? y ¿Cuál es el desempeño de los estudiantes? respecto a la enseñanza de histología y/o histopatología con MV en odontología. Material y métodos: Se consultaron las bases de datos: Pubmed, Scielo, Science Direct y Scopus, y 10 artículos fueron seleccionados. Resultados: La totalidad de estudios que evaluaron percepción y desempeño académico obtuvieron resultados a favor de la MV. Conclusiones: La MV tiene un futuro prometedor, pero más estudios con metodologías similares y que consideren la percepción de los académicos son requeridos.

ABSTRACT Virtual microscopy (VM) is being widely implemented in education and could lead to the replacement of light microscopy (LM). Objective: To provide a review of the literature based on the questions: What is the perception of academics and students? and What is the performance of students? regarding the teaching of histology and/or histopathology with VM in dentistry. Material and methods: The following databases were consulted: Pubmed, Scielo, Science Direct and Scopus, and 10 articles were selected. Results: All the studies that evaluated perception and academic performance obtained results in favor of VM. Conclusions: VM has a promising future, but more studies with similar methodologies and that consider the perception of academics are required.

Phenylalanine-Derived ß-Lactam TRPM8 Modulators. Configuration Effect on the Antagonist Activity.

Transient receptor potential cation channel subfamily M member 8 (TRPM8) is a Ca2+ non-selective ion channel implicated in a variety of pathological conditions, including cancer, inflammatory and neuropathic pain. In previous works we identified a family of chiral, highly hydrophobic ß-lactam derivatives, and began to intuit a possible effect of the stereogenic centers on the antagonist activity. To investigate the influence of configuration on the TRPM8 antagonist properties, here we prepare and characterize four possible diastereoisomeric derivatives of 4-benzyl-1-[(3'-phenyl-2'-dibenzylamino)prop-1'-yl]-4-benzyloxycarbonyl-3-methyl-2-oxoazetidine. In microfluorography assays, all isomers were able to reduce the menthol-induced cell Ca2+ entry to larger or lesser extent. Potency follows the order 3R,4R,2'R > 3S,4S,2'R ≅ 3R,4R,2'S > 3S,4S,2'S, with the most potent diastereoisomer showing a half inhibitory concentration (IC50) in the low nanomolar range, confirmed by Patch-Clamp electrophysiology experiments. All four compounds display high receptor selectivity against other members of the TRP family. Furthermore, in primary cultures of rat dorsal root ganglion (DRG) neurons, the most potent diastereoisomers do not produce any alteration in neuronal excitability, indicating their high specificity for TRPM8 channels. Docking studies positioned these ß-lactams at different subsites by the pore zone, suggesting a different mechanism than the known N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)-benzamide (AMTB) antagonist.

Manifestaciones orales asociadas a SARS-COV-2: Revisión de la literatura / Manifestações orais associadas ao SARS-COV-2: Revisão da literatura / Oral manifestations associated with SARS-COV-2: A literature review

Resumen Objetivo: Identificar las principales manifestaciones y describir su ubicación en la cavidad oral en pacientes COVID-19. Métodos: Se utilizaron las bases de datos PubMed, Medline, LILACS, LIVIVO, Web of Science y SciELO; utilizando los términos de búsqueda oral mucosa, oral mucosa lesion, oral manifestations, COVID-19 y SARS-CoV-2. Se eliminaron duplicados, luego se realizó preselección de artículos, y finalmente se aplicaron los criterios de inclusión y exclusión. Resultados: Se seleccionaron 47 publicaciones, encontrando manifestaciones orales en pacientes COVID-19 tales como alteración en gusto, xerostomía, úlceras, vesículas, entre otras; ubicándose en diferentes áreas de la mucosa oral. Conclusiones: Se necesitan más estudios para vislumbrar la posible etiopatogenia a nivel oral del SARS-CoV-2. Además, se destaca el rol del odontólogo en el equipo multidisciplinario y en la teleconsulta.

Resumo Objetivo: Identificar as principais manifestações e descobrir sua ubiquação na cavidade oral em pacientes com COVID-19. Método: Foram utilizadas as bases de dados PubMed, Medline, LILACS, LIVIVO, Web of Science e SciELO; utilizando os termos de pesquisa oral mucosa, oral mucosa lesion, oral manifestations, COVID-19 e SARS-CoV-2. Duplicadas foram removidas, depois uma pré-seleção de artigos foi feita, e finalmente os critérios de inclusão e exclusão foram aplicados. Resultados: Foram selecionadas 47 publicações, encontrando manifestações orais em pacientes com COVID-19, tais como alterações no paladar, xerostomia, ulcerações, vesículas, entre outros; localizando-as em diferentes áreas da mucosa oral. Conclusão: São precisos mais estudos pra vislumbrar a possível etiopatogenia a nível oral do SARS-CoV-2. Ademais, destaca-se o role do odontólogo na equipe multidisciplinar e na tele consulta.

Abstract Objective: Identify the main oral manifestations associated with COVID19 and describe their location in the oral cavity. Methods: The literature search was conducted in PubMed, Medline, LILACS, LIVIVO, Web of Science, and SciELO. The following words were searched for: oral mucosa, oral mucosa lesion, oral manifestations, COVID-19, and SARS-CoV-2. Duplicate articles were eliminated, and the pieces were shortlisted. Finally, inclusion and exclusion criteria were applied. Results: This study included 47 articles. The main oral manifestations in patients with COVID-19 are taste disorders, xerostomia, ulcers, vesicles, and others located in different areas of the oral mucosa. Conclusions More studies are needed to determine the potential oral etiopathogenesis of SARS-CoV-2. Moreover, dentists play a significant role in the multidisciplinary and telemedicine team.

Highly functionalized ß-lactams and 2-ketopiperazines as TRPM8 antagonists with antiallodynic activity.

The cool sensor transient receptor potential melastatin channel 8 (TRPM8) is highly expressed in trigeminal and dorsal root ganglia, playing a key role in cold hypersensitivity associated to different peripheral neuropathies. Moreover, these channels are aberrantly expressed in different cancers, and seem to participate in tumor progression, survival and invasion. Accordingly, the search for potent and selective TRPM8 modulators attracted great interest in recent years. We describe new heterocyclic TRPM8 antagonist chemotypes derived from N-cloroalkyl phenylalaninol-Phe conjugates. The cyclization of these conjugates afforded highly substituted ß-lactams and/or 2-ketopiperazine (KP) derivatives, with regioselectivity depending on the N-chloroalkyl group and the configuration. These derivatives behave as TRPM8 antagonists in the Ca2+ microfluorometry assay, and confirmed electrophysiologically for the best enantiopure ß-lactams 24a and 29a (IC50, 1.4 and 0.8 µM). Two putative binding sites by the pore zone, different from those found for typical agonists and antagonists, were identified by in silico studies for both ß-lactams and KPs. ß-Lactams 24a and 29a display antitumor activity in different human tumor cell lines (micromolar potencies, A549, HT29, PSN1), but correlation with TRPM8 expression could not be established. Additionally, compound 24a significantly reduced cold allodynia in a mice model of oxaliplatin-induced peripheral neuropathy.

A Qualified Success: Discovery of a New Series of ATAD2 Bromodomain Inhibitors with a Novel Binding Mode Using High-Throughput Screening and Hit Qualification.

The bromodomain of ATAD2 has proved to be one of the least-tractable proteins within this target class. Here, we describe the discovery of a new class of inhibitors by high-throughput screening and show how the difficulties encountered in establishing a screening triage capable of finding progressible hits were overcome by data-driven optimization. Despite the prevalence of nonspecific hits and an exceptionally low progressible hit rate (0.001%), our optimized hit qualification strategy employing orthogonal biophysical methods enabled us to identify a single active series. The compounds have a novel ATAD2 binding mode with noncanonical features including the displacement of all conserved water molecules within the active site and a halogen-bonding interaction. In addition to reporting this new series and preliminary structure-activity relationship, we demonstrate the value of diversity screening to complement the knowledge-based approach used in our previous ATAD2 work. We also exemplify tactics that can increase the chance of success when seeking new chemical starting points for novel and less-tractable targets.

Robustness of VMAT and 3DCRT plans toward setup errors in radiation therapy of locally advanced left-sided breast cancer with DIBH.

PURPOSE: The aim of our study was to evaluate and compare the robustness of treatment plans produced using the volumetric modulated arc-therapy (VMAT) and the standard three-dimensional conformal radiotherapy (3DCRT) techniques by estimating perturbed doses induced by localization offsets for deep inspiration breath-hold (DIBH) in locally advanced breast cancer radiation therapy. METHODS: Twenty patients with left breast carcinoma requiring radiation therapy were analysed in this planning study. Robust VMAT plans regarding minimum CTV doses and standard 3DCRT plans were produced, and perturbed doses were calculated in accordance with localization values from the weekly offline imaging protocol. Offsets from 5 weeks were summed to a perturbed overall treatment plan. Dose criteria for evaluation were coverage and homogeneity of the target, as well as doses to organs at risk. RESULTS: VMAT plans resulted in significantly better target coverage compared to 3DCRT, as well as lowered doses to heart and left anterior descending artery, while the perturbed doses were less variable for VMAT than 3DCRT plans. Homogeneity was significantly improved in VMAT plans. The statistical analysis taking all organs into account found that VMAT plans were more robust than 3DCRT to localization offsets (p = .001). The overall mean setup-deviation for the DIBH-patients was less than 2 mm in all directions. CONCLUSIONS: VMAT plans were more robust on average than conventional 3DCRT plans for DIBH when localization errors were taken into consideration. The combination of robust VMAT planning and DIBH generally improves the homogeneity and target doses.

Intrafractional baseline drift during free breathing breast cancer radiation therapy.

BACKGROUND: Intrafraction motion in breast cancer radiation therapy (BCRT) has not yet been thoroughly described in the literature. It has been observed that baseline drift occurs as part of the intrafraction motion. This study aims to measure baseline drift and its incidence in free-breathing BCRT patients using an in-house developed laser system for tracking the position of the sternum. MATERIALS AND METHODS: Baseline drift was monitored in 20 right-sided breast cancer patients receiving free breathing 3D-conformal RT by using an in-house developed laser system which measures one-dimensional distance in the AP direction. A total of 357 patient respiratory traces from treatment sessions were logged and analysed. Baseline drift was compared to patient positioning error measured from in-field portal imaging. RESULTS: The mean overall baseline drift at end of treatment sessions was -1.3 mm for the patient population. Relatively small baseline drift was observed during the first fraction; however it was clearly detected already at the second fraction. Over 90% of the baseline drift occurs during the first 3 min of each treatment session. The baseline drift rate for the population was -0.5 ± 0.2 mm/min in the posterior direction the first minute after localization. Only 4% of the treatment sessions had a 5 mm or larger baseline drift at 5 min, all towards the posterior direction. Mean baseline drift in the posterior direction in free breathing BCRT was observed in 18 of 20 patients over all treatment sessions. CONCLUSIONS: This study shows that there is a substantial baseline drift in free breathing BCRT patients. No clear baseline drift was observed during the first treatment session; however, baseline drift was markedly present at the rest of the sessions. Intrafraction motion due to baseline drift should be accounted for in margin calculations.

CT image quality over time: comparison of image quality for six different CT scanners over a six-year period.

UNSCEAR concluded that increased use of CT scanning caused dramatic changes in population dose. Therefore, international radiation protection authorities demand: 1) periodical quality assurance tests with respect to image quality and radiation dose, and 2) optimization of all examination protocols with respect to image quality and radiation dose. This study aimed to evaluate and analyze multiple image quality parameters and variability measured throughout time for six different CT scanners from four different vendors, in order to evaluate the current methodology for QA controls of CT systems. The results from this study indicate that there is minor drifting in the image noise and uniformity and in the spatial resolution over time for CT scanners, independent of vendors. The HU for different object densities vary between different CT scanner models from different vendors, and over time for one specific CT scanner. Future tests of interphantom and intraphantom variations, along with inclusion of more CT scanners, are necessary to establish robust baselines and recommendations of methodology for QA controls of CT systems, independent of model and vendor.

Tumors exposed to acute cyclic hypoxia show increased vessel density and delayed blood supply.

The purpose of this study was to investigate the effect of acute cyclic hypoxia on tumor vasculature. A-07 human melanoma xenografts growing in dorsal window chambers were used as tumor model. Acute cyclic hypoxia was induced by periodically exposing tumor-bearing mice to a low oxygen atmosphere. The hypoxia treatment consisted of 12 cycles of 10 min of low O(2) (8% O(2) in N(2)) followed by 10 min of air for a total of 4 hr. The treatment started the first day after tumor initiation, and was given daily for 9 days. Vascular morphology was assessed from high-resolution transillumination images, and tumor blood supply was assessed from first-pass imaging movies recorded after a bolus of 155 kDa tetramethylrhodamine isothiocyanate-labeled dextran had been administered intravenously. Hypoxia-treated tumors showed increased vessel density, decreased interstitial distance, and delayed blood supply compared to control tumors. The increase in vessel density was attributed to an increased number of small vessels. In conclusion, acute cyclic hypoxia induced angiogenesis in A-07 tumors resulting in increased density of small-diameter vessels and delayed tumor blood supply.

The crystal structure of galactitol-1-phosphate 5-dehydrogenase from Escherichia coli K12 provides insights into its anomalous behavior on IMAC processes.

Endogenous galactitol-1-phosphate 5-dehydrogenase (GPDH) (EC 1.1.1.251) from Escherichia coli spontaneously interacts with Ni(2+)-NTA matrices becoming a potential contaminant for recombinant, target His-tagged proteins. Purified recombinant, untagged GPDH (rGPDH) converted galactitol into tagatose, and d-tagatose-6-phosphate into galactitol-1-phosphate, in a Zn(2+)- and NAD(H)-dependent manner and readily crystallized what has permitted to solve its crystal structure. In contrast, N-terminally His-tagged GPDH was marginally stable and readily aggregated. The structure of rGPDH revealed metal-binding sites characteristic from the medium-chain dehydrogenase/reductase protein superfamily which may explain its ability to interact with immobilized metals. The structure also provides clues on the harmful effects of the N-terminal His-tag.

Discovery of a potent and selective 5-ht5A receptor antagonist by high-throughput chemistry.

High-throughput screening of an array of biphenylmethylamines synthesised by high-throughput solid-phase chemistry resulted in the identification of compounds with high-affinity for the 5-ht5A receptor. The structure-activity relationship within this series and further array synthesis led to the identification of the biphenylmethylamine derivative 11, a potent and selective 5-ht5A receptor antagonist.