A pH-enhanced resolution in benchtop NMR spectroscopy.

NMR spectroscopy is one of the most potent methods in analytical chemistry. NMR titration experiments are particularly useful since they measure molecular binding affinities and other concentration-dependent effects. These experiments, however, require a long series of measurements. An alternative to these serial measurements has recently been presented, exploiting a pH (or generally - a concentration) gradient along the NMR tube. The proposed experiment, although efficient, was based on the sensitivity- and hardware-demanding chemical shift imaging (CSI) method. Thus, it is practically limited to high-resolution NMR spectrometers. This paper proposes modifying and adapting the approach to the popular and cost-efficient benchtop NMR machines. Instead of CSI, we use a device that shifts the NMR tube vertically to measure the spectra of different sample volumes, which have different pH values due to the established gradient along the tube. We demonstrate the potential of the method on the test samples of L-tyrosine and 2,6-lutidine, and two real samples from the food industry - an infant formula and an energy drink. The proposed method boosts spectral resolution and allows for the sampling of a broader range of pH values when compared to the original approach.

Linear discriminant analysis reveals hidden patterns in NMR chemical shifts of intrinsically disordered proteins.

NMR spectroscopy is key in the study of intrinsically disordered proteins (IDPs). Yet, even the first step in such an analysis-the assignment of observed resonances to particular nuclei-is often problematic due to low peak dispersion in the spectra of IDPs. We show that the assignment process can be aided by finding "hidden" chemical shift patterns specific to the amino acid residue types. We find such patterns in the training data from the Biological Magnetic Resonance Bank using linear discriminant analysis, and then use them to classify spin systems in an α-synuclein sample prepared by us. We describe two situations in which the procedure can greatly facilitate the analysis of NMR spectra. The first involves the mapping of spin systems chains onto the protein sequence, which is part of the assignment procedure-a prerequisite for any NMR-based protein analysis. In the second, the method supports assignment transfer between similar samples. We conducted experiments to demonstrate these cases, and both times the majority of spin systems could be unambiguously assigned to the correct residue types.

Fenología reproductiva de Prunus lundelliana Standl. (Rosaceae), un árbol en peligro de extinción con potencial para restaurar bosques nubosos de Mesoamérica / Reproductive phenology of Prunus lundelliana Standl. (Rosaceae), an endangered tree with potential to restore cloud forests of Mesoamerica

La fenología estudia los cambios estacionales en los ciclos de vida de los organismos. Una utilidad de la fenología, es que permite establecer periodos en que se pueden colectar semillas para programas de restauración ecológica. Por lo que, de abril de 2017 a mayo de 2019, en el volcán Tacaná, San Marcos, Guatemala, se estableció la estaciona-lidad, variación anual, sincronía, intensidad y duración de las fenofases reproductivas de Prunus lundelliana Standl. Aproximadamente cada 15 días, en 10 individuos se registró la presencia e intensidad de las flores (botones y abiertas) y frutos (inmaduros y maduros). Los datos se analizaron con estadística circular, encontrándose que todas la fenofases fueron estacionales y que solo el patrón de los frutos inmaduros varió significativamente entre los dos periodos. La sincronía fue principalmente alta y la intensidad no superó el 40%. En ambos periodos las intensidades menores las presentaron los frutos maduros (17 y 25%). Los índices de actividad e intensidad se correlacionaron significativamente, por lo que los ángulos medios fueron semejantes en las fenofases y periodos de estudio. Los picos de actividad-in-tensidad de las flores abiertas y de los frutos maduros ocurrieron durante los meses secos (noviembre-abril), patrón que se ha registrado en otros bosques nubosos. La duración de las fenofases varió entre 2.5-3.5 meses, siendo la más pequeña la de frutos maduros. Para fines de manejo, la colecta de frutos maduros puede hacerse desde mediados de marzo hasta finales de mayo, sin embargo, se sugiere hacerlo principalmente entre el 15 de abril y el 15 de mayo.

Phenology studies the seasonal changes in the life cycle of organisms. Phenological data allow to set the periods in which the seeds can be collected for ecological restoration programs. From April, 2017 to May, 2019, in Taca-ná volcano, San Marcos, Guatemala, it was established the seasonality, annual variation, synchrony, intensity, and duration of the reproductive phenophases of Prunus lundelliana Standl. About every 15 days, 10 individuals were observed and it was recorded the presence and intensity of flowers (buds and blossom flowers) and fruits (immature and mature fruits). The data was analyzed with circular statistics, finding that all the phenophases were seasonally distributed and only the immature fruits pattern significantly variated between the two periods. The synchrony was mainly high and the intensity did not exceed 40%. In both of the study periods, the lesser intensities were presented by the mature fruits (17 and 25%). The activity and intensity indexes were significantly correlated; therefore the mid angles were alike in the phenophases and study periods. The activity-intensity highs of blossom flowers and of mature fruits happened in the dry months (November to April), a pattern that has been registered in other cloud forests. The duration of the phenophases ranged from 2.5 to 3.5 months, being the shortest the mature fruits phenophase. For environmental management purposes, the collection of mature fruits can be done from the middle of March to the end of May, nonetheless, it should be done mainly between April 15th and May 15th.

Enhancing benchtop NMR spectroscopy by means of sample shifting.

Benchtop NMR spectrometers have become widely available over the last decade. They are now used successfully in various branches of chemistry. Their popularity continues to grow due to their low price and almost zero running costs. However, benchtop spectrometers suffer from low resolution and sensitivity compared to the high-field spectrometers used in NMR labs for several decades. In this article we present a solution for boosting the sensitivity of benchtop NMR spectrometers in a multi-scan experiment and improving their capabilities in quantitative measurement. Our solution involves the synchronized shifting of a sample to preserve its high nuclear polarization during the measurement. We performed several experiments using different samples to confirm this improved performance: an 1H NMR experiment for 4,4-dimethoxy-2-butanone, and 13C NMR experiments for benzyl salicylate, the liquid pharmaceutical product Acerin (skin solution), and a mixture of m-anisaldehyde and (R)-(+)-limonene.

Non-Stationary Complementary Non-Uniform Sampling (NOSCO NUS) for Fast Acquisition of Serial 2D NMR Titration Data.

NMR spectroscopy offers unique benefits for ligand binding studies on isotopically labelled target proteins. These benefits include atomic resolution, direct distinction of binding sites and modes, a lowest detectable affinity limit, and function independent setup. Yet, retracing protein signal assignments from apo to holo states to derive exact dissociation constants and chemical shift perturbation amplitudes (for ligand docking and structure-based optimization) requires lengthy titration series of 2D heteronuclear correlation spectra at variable ligand concentration that may exceed the protein's lifetime and available spectrometer time. We present a novel method to overcome this critical limitation, based on non-stationary complementary non-uniform sampling (NOSCO NUS) combined with a robust particle swarm optimization algorithm. We illustrate its potential in two challenging studies with very distinct protein sizes and binding affinities, showing that NOSCO NUS can reduce measurement times by an order of magnitude to make such highly informative NMR titration studies more broadly feasible.

A fast field-cycling MRI relaxometer for physical contrasts design and pre-clinical studies in small animals.

We present a fast field-cycling NMR relaxometer with added magnetic resonance imaging capabilities. The instrument operates at a maximum proton Larmor frequency of 5 MHz for a sample volume of 35 mL. The magnetic field homogeneity across the sample is 1400 ppm. The main field is generated with a notch-coil electromagnet of own design, fed with a current whose stability is 220 ppm. We show that images of reasonable quality can still be produced under such conditions. The machine is being designed for concept testing of the involved instrumentation and specific contrast agents aimed for field-cycling magnetic resonance imaging applications. The general performance of the prototype was tested through localized relaxometry experiments, T1-dispersion weighted images, temperature maps and T1-weighted images at different magnetic field intensities. We introduce the concept of positive and negative contrast depending on the use of pre-polarized or non-polarized sequences. The system is being improved for pre-clinical studies in small animals.

Prácticas de cuidado cultural en el continuo reproductivo de la mujer Embera Katio del Alto Sinú / Prácticas de atendimento cultural no continuo reprodutivo de mulheres Embera Katio del Alto Sinú / Cultural care practices in the reproductive continuum of Embera Katio women of the Alto Sinú

Resumen: El cuidado está presente en todas las culturas y tiene características diferentes. Una etapa del curso de vida donde se evidencia con más claridad el cuidado cultural en las comunidades indígenas es en la etapa reproductiva. Este trabajo se trata acerca de una investigación cualitativa de tipo etnográfico interpretativo, que busca describir, explicar e interpretar las prácticas de cuidado cultural en el continuo reproductivo de la mujer Embera Katio. Emergieron cuatro categorías de análisis: preparación de la mujer Embera para albergar la semilla que brotará de sus entrañas; resguardando la semilla del pueblo Embera en el vientre materno; cuando brota la semilla: surge una nueva vida y, la armonía y restablecimiento de la salud en la diada madre-hijo. Se concluye que el continuo reproductivo de la mujer Embera Katio está representado por un conjunto de prácticas de cuidado de orden intergeneracional, que se encuentran soportadas en un conocimiento y comportamiento cultural específico, que garantiza la protección de la mujer y su descendencia. Se destacan en esta síntesis interpretativa las siguientes prácticas de cuidado cultural: el Jemené: rito que marca el inicio de la mujer Embera Katio a la vida fértil; la alimentación: una manera de preservar el bienestar de la madre y su hijo por nacer; la verticalización del parto y el uso de plantas medicinales durante el trabajo de parto; los consejos y el acompañamiento de la partera tradicional durante el embarazo, parto y posparto y por último, el reposo y la armonía de la madre y el recién nacido en el posparto.

Resumo: O cuidado está presente em todas as culturas e possui características diferentes em cada uma delas; uma etapa do curso de vida em que o cuidado cultural nas comunidades indígenas é mais evidente é no estágio reprodutivo. Metodologia: Pesquisa interpretativa etnográfica qualitativa, que procura descrever, explicar e interpretar práticas de cuidado cultural no continuum reprodutivo de mulheres de Embera Katio. Resultados: emergiram quatro categorias de análise, conforme descrito a seguir: preparação da mulher Embera para abrigar a semente que brotará de dentro dela; abrigando a semente do povo Embera no ventre da mãe; Quando a semente brota: uma nova vida emerge e a harmonia e restauração da saúde na díade mãe-filho. Conclusões: o continuum reprodutiva das mulheres Embera Katio, é representado por um conjunto de práticas de ordem cuidado intergeracional, que são suportados em conhecimentos específicos e comportamento cultural, que garante a protecção das mulheres e sua prole. As seguintes práticas de cuidado cultural destacam-se nesta síntese interpretativa: o jemené: rito que marca o início da mulher Embera Katio para a vida fértil; alimentação: uma forma de preservar o bem-estar da mãe e do feto; a verticalização do parto e o uso de plantas medicinais durante o trabalho de parto; o aconselhamento e acompanhamento da parteira tradicional durante a gravidez, parto e pós-parto e, por último, descanso e harmonia da mãe e do recém-nascido no período pós-parto.

Abstract: Care is present in all cultures and has different characteristics in each one of them; a stage of the life course where the cultural care in the indigenous communities is most clearly evidente is in the reproductive stage. Qualitative ethnographic interpretive research, which seeks to describe, explain and interpret cultural care practices in the reproductive continuum of Embera Katio women. Results: four categories of analysis emerged as described below: preparation of the Embera woman to house the seed that will sprout from her; sheltering the seed of the Embera people in the mother's womb; when the seed sprouts: a new life emerges and the harmony and restoration of health in the mother-child dyad. Conclusions: the reproductive continuum of the Embera Katio woman is represented by a set of care practices of intergenerational order, which are supported by knowledge and specific cultural behavior, which guarantees the protection of the woman and her offspring. The following cultural care practices stand out in this interpretive synthesis: the Jemené: rite that marks the beginning of the Embera Katio woman to the fertile life; feeding: a way to preserve the welfare of the mother and her unborn child; the verticalization of childbirth and the use of medicinal plants during labor; the advice and accompaniment of the traditional midwife during pregnancy, childbirth and postpartum and, lastly, rest and harmony of the mother and newborn in the postpartum period.

Abrazando mi historia de vida: la experiencia de vivir con cáncer siendo adolescente / HUGGING MY LIFE HISTORY: EXPERIENCING CANCER AS AN ADOLESCENT

Objetivo. Explorar la experiencia de vida de un adolescente con cáncer. Materiales y métodos. Estudio cualitativo, con caso único, basado en historia de vida; la técnica utilizada fue la entrevista a profundidad y los resultados se examinaron con base en una versión simplificada de la propuesta de Amedeo Giorgi. Resultados. emergieron dos temas centrales: Diagnóstico: implicaciones para la vida personal, social y familiar de un adolescente con cáncer y el apoyo familiar como soporte indispensable para afrontar la enfermedad. Conclusiones. El estudio permitió comprender el significado que otorga un adolescente a la experiencia de vivir con osteosarcoma, revelando un mundo distinto y poco explorado. El apoyo de la familia, fue indispensable para la superación del cáncer en el adolescente, podría decirse, que un soporte social sólido en el paciente, favorece los procesos de afrontamiento y adaptación en la experiencia de vivir y sobreponerse a esta condición. En ocasiones el cáncer infantil se visualiza como una enfermedad devastadora, que tiene serias implicaciones para el paciente y su familia, obligándolos a reorganizar su dinámica familiar y social, para adaptarse y luchar contra la enfermedad

Objective.To explore the life history of an adolescent who experiences cancer. Materials and methods. This is a qualitative study based on single-case life history. In-depth interview was used, and the results were analyzed using a reduced version of Amedeo Giorgi's method. Result. Two central themes emerged from the data: Diagnosis implications for the personal, social and, family life of a teenager suffering from cancer and family support as crucial in coping with the disease. The support of the family was essential in overcoming cancer in an adolescent. Solid social support to the patient favored the processes of living, adapting, coping with and, overcoming cancer. Conclusion.The study allowed the researchers to understand an adolescent's experience of living with osteosarcoma, revealing a particular world that has not been explored in depth. Sometimes childhood cancer is considered a devastating disease, which has severe implications for the patient and his family forcing them to reorganize their family and social dynamics to adapt and fight against that disease

Longitudinal gradient coils with enhanced radial uniformity in restricted diameter: Single-current and multiple-current approaches.

An important requirement for a gradient coil is that the uniformity of the generated magnetic field gradient should be maximal within the active volume of the coil. For a cylindrical geometry, the radial uniformity of the gradient turns critic, particularly in cases where the gradient-unit has to be designed to fit into the inner bore of a compact magnet of reduced dimensions, like those typically used in fast-field-cycling NMR. In this paper we present two practical solutions aimed to fulfill this requirement. We propose a matrix-inversion optimization algorithm based on the Biot-Savart law, that using a proper cost function, allows maximizing the uniformity of the gradient and power efficiency. The used methodology and the simulation code were validated in a single-current design, by comparing the computer simulated field map with the experimental data measured in a real prototype. After comparing the obtained results with the target field approach, a multiple-element coil driven by independent current sources is discussed, and a real prototype evaluated. Opposed equispaced independent windings are connected in pairs conforming an arrangement of independent anti-Helmholtz units. This last coil seizes 80% of its radial dimension with a gradient uniformity better than 5%. The design also provides an adaptable region of uniformity along with adjustable coil efficiency.

Reliability of the BI-RADS Final Assessment Categories and Management Recommendations in a Telemammography Context.

PURPOSE: The aim of this study was to evaluate the intradevice and interdevice reliability of four alternatives for telemammography-computed radiography, printed film, a film digitizer, and a digital camera-in terms of interpretation agreement when using the BI-RADS® lexicon. METHODS: The ethics committee of the authors' institution approved this retrospective study. A factorial design with repeated measures with 1,960 interpretations was used (70 patients, seven radiologists, and four devices). Reliability was evaluated using the κ coefficient for intradevice and interdevice agreement on malignancy classification and on BI-RADS final assessment category. RESULTS: Agreement on malignancy classification was higher than agreement for BI-RADS final assessment category. Interdevice agreement on malignancy classification between the film digitizer and computed radiography was ranked as almost perfect (P < .001), whereas interdevice agreement for the other alternatives was ranked as substantial (P < .001), with observed agreement ranging from 85% to 91% and κ values ranging from 0.70 to 0.81. Interdevice agreement on BI-RADS final assessment category was ranked as substantial or moderate (P < .001), with observed agreement ranging from 64% to 77% and κ values ranging from 0.52 to 0.69. Interdevice agreement was higher than intradevice agreement. CONCLUSIONS: The results of this study show very high interdevice agreement, especially for management recommendations derived from malignancy classification, which is one of the most important outcomes in screening programs. This study provides evidence to suggest the interchangeability of the devices evaluated, thereby enabling the provision of low-cost medical imaging services to underserved populations.

Guía práctica y resultados de la implementación de un programa de auditoría y calidad en imágenes mamarias / Practical Guide and Results of the Implementation of an Audit and Quality Program in Breast Imaging

Objetivo: Describir la experiencia del Centro de Diagnóstico para la Mujer, de la Fundación Santa Fe de Bogotá (FSFB), en la implementación de un sistema práctico de auditoría en imágenes mamarias y su utilidad en los procesos de calidad, basados en parámetros establecidos por el American College of Radiology (ACR). Métodos: Evaluación de los indicadores propuestos por el ACR mediante bases de datos y sistemas de información de imágenes de la FSFB (enero 2012-diciembre 2014). Se incluyeron todos los estudios mamográficos y biopsias de mama realizadas por ecografía y estereotaxia. Los resultados se compararon con los descritos en BIRADS ® 5ta. edición. Se realizó una búsqueda de la literatura en PubMed para definir el estado del arte de los procesos de auditoría en imágenes mamarias. Resultados: Incluimos 13 artículos originales y 4 guías internacionales de auditoría en imágenes mamarias. Se evaluaron 19.132 mamografías (6.060 en 2012, 6.568 en 2013 y 6.504 en 2014). El 95 % de las mamografías correspondieron a tamizaje de oportunidad. El rellamado global disminuyó 19,6 %, el VPP de las biopsias realizadas aumentó a 15,36 % y mejoró la detección de cáncer invasivo de menor tamaño con una diferencia significativa entre 2013 y 2014 (p=0,03). La detección del cáncer mínimo se encuentra en 54,23 %. Conclusión: Los programas de control de la calidad y auditoría en imágenes mamarias basados en recomendaciones internacionales permiten garantizar resultados clínicamente relevantes en pacientes que asisten a tamizaje mamográfico. Las recomendaciones de sociedades internacionales proveen un continuo mejoramiento en los indicadores.

Objective: To describe the experience of the Center of Diagnosis for Women, of the Fundación Santa Fe de Bogotá (FSFB) in the implementation of a practical system of auditing in mammary images and its utility in quality processes, based on parameters established by the American College of Radiology benchmarks. Methods: We evaluated the benchmarks proposed by the ACR's audit program, based on our imaging databases and FSFB imaging information between January 2012 and December 2014. We include all mammograms, ultrasound-guided and stereotacticguided breast biopsies. The results were compared with those described in BI-RADS 5 edition. A literature review was performed using PubMed to define the state of the art of the breast imaging audit process. Results: We included 13 original articles and 4 international guidelines of breast imaging audit. We included 19132 mammograms, 6060 from 2012, 6568 from 2013 and 6504 from 2014. 95% of the mammograms belong to opportunity screening program. Recall rate decreased in 19.6%, PPV of the biopsies increased to 15,36% and the detection of smaller invasive cancer increased with significant difference between 2013 and 2014 (p=0.03). Minimal breast cancer detection corresponds to 54.34%. Conclusion: Quality Control and Audit programs in breast imaging based on international recommendations allow assuring clinical results in patients from a screening program. The recommendations of international societies provide a medium to provide a continuous improvement in the indicators.

Noninferiority and Equivalence Evaluation of Clinical Performance among Computed Radiography, Film, and Digitized Film for Telemammography Services.

Objective. The aim of this study was to evaluate and compare the clinical performance of different alternatives to implement low-cost screening telemammography. We compared computed radiography, film printed images, and digitized films produced with a specialized film digitizer and a digital camera. Material and Methods. The ethics committee of our institution approved this study. We assessed the equivalence of the clinical performance of observers for cancer detection. The factorial design included 70 screening patients, four technological alternatives, and cases interpreted by seven radiologists, for a total of 1,960 observations. The variables evaluated were the positive predictive value (PPV), accuracy, sensitivity, specificity, and the area under the receiver operating characteristic curves (AUC). Result. The mean values for the observed variables were as follows: accuracy ranged from 0.77 to 0.82, the PPV ranged from 0.67 to 0.68, sensitivity ranged from 0.64 to 0.74, specificity ranged from 0.87 to 0.90, and the AUC ranged from 0.87 to 0.90. At a difference of 0.1 to claim equivalence, all alternatives were equivalent for all variables. Conclusion. Our findings suggest that telemammography screening programs may be provided to underserved populations at a low cost, using a film digitizer or a digital camera.