Clinical validation of 3D-printed swabs in adults and children for SARS-CoV-2 detection.

Throughout the entire coronavirus disease 19 (COVID-19) pandemic, there were disruptions in the supply chain of test materials around the world, primarily in poor- and middle-income countries. The use of 3D prints is an alternative to address swab supply shortages. In this study, the feasibility of the clinical use of 3D-printed swabs for oropharyngeal and nasopharyngeal sampling for the detection of SARS-CoV-2 infection was evaluated. For that purpose, paired samples with the 3D printed and the control swabs were taken from 42 adult patients and 10 pediatric patients, and the results obtained in the detection of SARS-CoV-2 by reverse transcription and quantitative polymerase chain reaction (RT-qPCR) were compared. Additionally, in those cases where the result was positive for SARS-CoV-2, the viral load was calculated by means of a mathematical algorithm proposed by us. For both adults and children, satisfactory results were obtained in the detection of SARS-CoV-2 by RT-qPCR; no significant differences were found in the quantification cycle values between the 3D-printed swab samples and the control samples. Furthermore, we corroborated that the 3D-printed swabs caused less discomfort and pain at the time of sampling. In conclusion, this study shows the feasibility of routinely using 3D-printed swabs for both adults and children. In this way, it is possible to maintain local and cheaper consumption along with fewer distribution difficulties.

Correlation of liver fibrosis quantification by morphometry using HepaScan with the analysis of liver biopsies. A pilot study.

BACKGROUND: The gold standard for determining the degree of liver fibrosis (LF) continues to be biopsy evaluation. There are morphometry techniques that allow LF to be quantified on histopathological studies. OBJECTIVE: To measure the correlation between LF histological evaluation and fibrosis percentage (FP) morphometric quantification using the HepaScan software. MATERIAL AND METHODS: Observational, analytical, cross-sectional, prospective, prolective pilot study in which liver histological sections from 29 people who died from some liver disease and from 22 people who died from other causes (controls) were analyzed. FP was calculated with HepaScan on digital photographs of histological sections stained with the Masson technique, comparing it with the diagnosis established by three expert pathologists. RESULTS: Four-hundred and one images from the group with liver disease and 250 from the control group were analyzed. Inter-observer agreement had a kappa index of 0.329. There were FP statistically significant differences (p = 0.0001) between histopathological classification groups. HepaScan predictive capacity based on the area under the receiver operating characteristic curve was 0.983, 0.812, and 0.895 for mild, moderate, and severe fibrosis, respectively. CONCLUSIONS: HepaScan showed very good performance for evaluating FP in histological sections, which is why it can contribute to qualitative pathological diagnosis.

ANTECEDENTES: El estándar de oro para determinar el grado de fibrosis hepática (FH) continúa siendo la evaluación de la biopsia. Existen técnicas de morfometría que permiten cuantificar la FH en estudios histopatológicos. OBJETIVO: Medir la correlación entre la evaluación histológica de FH y la cuantificación por morfometría del porcentaje de fibrosis (PF) mediante HepaScan. MATERIAL Y MÉTODOS: Estudio piloto observacional, analítico, transversal, prospectivo y prolectivo en el que se analizaron cortes histopatológicos de hígado de 29 personas fallecidas por alguna hepatopatía y 22 personas fallecidas por otras causas (controles). El PF se calculó con HepaScan en fotografías digitales de cortes histológicos teñidos con la técnica Masson, comparándolo con el diagnóstico de tres patólogos expertos. RESULTADOS: Fueron analizadas 401 imágenes del grupo con hepatopatía y 250 del grupo de control. La concordancia interobservador tuvo un índice kappa de 0.329. Entre los grupos de clasificación histopatológica existieron diferencias estadísticas en el PF (p = 0.0001). La capacidad predictiva de HepaScan con base en el área bajo la curva característica operativa del receptor fue de 0.983, 0.812 y 0.895 para fibrosis leve, moderada y severa, respectivamente. CONCLUSIONES: HepaScan mostró muy buen desempeño para evaluar el PF en cortes histológicos, por lo que puede coadyuvar al diagnóstico patológico cualitativo.

Correlación de la cuantificación de fibrosis hepática por morfometría mediante HepaScan con el análisis de las biopsias hepáticas. Estudio piloto / Correlation of liver fibrosis quantification by morphometry using HepaScan with the analysis of liver biopsies. A pilot study

Resumen Antecedentes: El estándar de oro para determinar el grado de fibrosis hepática (FH) continúa siendo la evaluación de la biopsia. Existen técnicas de morfometría que permiten cuantificar la FH en estudios histopatológicos. Objetivo: Medir la correlación entre la evaluación histológica de FH y la cuantificación por morfometría del porcentaje de fibrosis (PF) mediante HepaScan. Material y métodos: Estudio piloto observacional, analítico, transversal, prospectivo y prolectivo en el que se analizaron cortes histopatológicos de hígado de 29 personas fallecidas por alguna hepatopatía y 22 personas fallecidas por otras causas (controles). El PF se calculó con HepaScan en fotografías digitales de cortes histológicos teñidos con la técnica Masson, comparándolo con el diagnóstico de tres patólogos expertos. Resultados: Fueron analizadas 401 imágenes del grupo con hepatopatía y 250 del grupo de control. La concordancia interobservador tuvo un índice kappa de 0.329. Entre los grupos de clasificación histopatológica existieron diferencias estadísticas en el PF (p = 0.0001). La capacidad predictiva de HepaScan con base en el área bajo la curva característica operativa del receptor fue de 0.983, 0.812 y 0.895 para fibrosis leve, moderada y severa, respectivamente. Conclusiones: HepaScan mostró muy buen desempeño para evaluar el PF en cortes histológicos, por lo que puede coadyuvar al diagnóstico patológico cualitativo.

Abstract Background: The gold standard for determining the degree of liver fibrosis (LF) continues to be biopsy evaluation. There are morphometry techniques that allow LF to be quantified on histopathological studies. Objective: To measure the correlation between LF histological evaluation and fibrosis percentage (FP) morphometric quantification using the HepaScan software. Material and methods: Observational, analytical, cross-sectional, prospective, prolective pilot study in which liver histological sections from 29 people who died from some liver disease and from 22 people who died from other causes (controls) were analyzed. FP was calculated with HepaScan on digital photographs of histological sections stained with the Masson technique, comparing it with the diagnosis established by three expert pathologists. Results: Four-hundred and one images from the group with liver disease and 250 from the control group were analyzed. Inter-observer agreement had a kappa index of 0.329. There were FP statistically significant differences (p = 0.0001) between histopathological classification groups. HepaScan predictive capacity based on the area under the receiver operating characteristic curve was 0.983, 0.812, and 0.895 for mild, moderate, and severe fibrosis, respectively. Conclusions: HepaScan showed very good performance for evaluating FP in histological sections, which is why it can contribute to qualitative pathological diagnosis.

Validation of 3D-Printed Swabs for Sampling in SARS-CoV-2 Detection: A Pilot Study.

In this pilot study, we characterize and evaluate 3D-printed swabs for the collection of nasopharyngeal and oropharyngeal secretion samples for the SARS-CoV-2 detection. Swabs are made with the fused deposition modeling technique using the biopolymer polylactic acid (PLA) which is a medical-grade, biodegradable and low-cost material. We evaluated six swabs with mechanical tests in a laboratory and in an Adult Human Simulator performed by healthcare professionals. We proved the adequacy of the PLA swab to be used in the gold standard reverse transcriptase-polymerase chain reaction (qRT-PCR) for viral RNA detection. Then, we did in vitro validation for cell collection using the 3D-printed swabs and RNA extraction for samples from 10 healthy volunteers. The 3D-printed swabs showed good flexibility and maneuverability for sampling and at the same time robustness to pass into the posterior nasopharynx. The PLA did not interfere with the RNA extraction process and qRT-PCR test. When we evaluated the expression of the reference gene (RNase P) used in the SARS-CoV-2 detection, the 3D-printed swabs showed good reproducibility in the threshold cycle values (Ct = 23.5, range 19-26) that is comparable to control swabs (Ct = 24.7, range 20.8-32.6) with p value = 0.47. The 3D-printed swabs demonstrated to be a reliable, and an economical alternative for mass use in the detection of SARS-CoV-2.

Effective Capacitance from Equivalent Electrical Circuit as a Tool for Monitoring Non-Adherent Cell Suspensions at Low Frequencies.

Analyzing the electrical double layer (EDL) in electrical impedance spectroscopy (EIS) measurement at low frequencies remains a challenging task for sensing purposes. In this work, we propose two approaches to deal with the EDL in measuring impedance for particles and non-adherent cells in an electrolytic suspension. The first approach is a simple procedure to compute a normalized electrical impedance spectrum named dispersed medium index (DMi). The second is the EIS modeling through an equivalent electric circuit based on the so-called effective capacitance (Cef), which unifies the EDL phenomena. Firstly, as an experiment under controlled conditions, we examine polymer particles of 6, 15, and 48 µm in diameter suspended in a 0.9% sodium chloride solution. Subsequently, we used K-562 cells and leukocytes suspended in a culture medium (RPMI-1640 supplemented) for a biological assay. As the main result, the DMi is a function of the particle concentration. In addition, it shows a tendency with the particle size; regardless, it is limited to a volume fraction of 0.03 × 10-4 to 58 × 10-4. The DMi is not significantly different between K-562 cells and leukocytes for most concentrations. On the other hand, the Cef exhibits high applicability to retrieve a function that describes the concentration for each particle size, the K-562 cells, and leukocytes. The Cef also shows a tendency with the particle size without limitation within the range tested, and it allows distinction between the K-562 and leukocytes in the 25 cells/µL to 400 cells/µL range. We achieved a simple method for determining an Cef by unifying the parameters of an equivalent electrical circuit from data obtained with a conventional potentiostat. This simple approach is affordable for characterizing the population of non-adherent cells suspended in a cell culture medium.

Endogenous Fluorescence Dissimilarity Assessment of Four Potential Biomarkers of Early Liver Fibrosis by Preservation Media Effect.

Build-up of extracellular matrix in liver fibrosis results in changes on endogenous molecules expression that may be studied through the fluorescence characterization of ex vivo liver samples. To the best of our knowledge, no investigations have provided in-depth evidence and discussion on the changes of the endogenous fluorescence in ex vivo tissue due to the effects of the preservation media. In this work, we contrast and analyze the endogenous fluorescence from tryptophan, vitamin A, hydroxyproline and elastin cross-links potential biomarkers of the liver fibrosis, in in vivo measurements and liver samples preserved on formaldehyde, and two standard preservation media. As it is known, chemical changes in tissue, caused by formaldehyde fixation, alter the endogenous fluorescence spectra. We propose the use of phosphate-buffered saline (PBS), and Iscove's Modified Dulbecco's Medium (IMDM) to elude the fluorescence changes. PBS and IMDM showed to maintain the endogenous fluorescence characteristics similar to in vivo conditions. The results of this work point the way for a more reliable assessment of endogenous fluorescence in ex vivo hepatic studies.

ZIF Nanocrystal-Based Surface Acoustic Wave (SAW) Electronic Nose to Detect Diabetes in Human Breath.

In the present work, a novel, portable and innovative eNose composed of a surface acoustic wave (SAW) sensor array based on zeolitic imidazolate frameworks, ZIF-8 and ZIF-67 nanocrystals (pure and combined with gold nanoparticles), as sensitive layers has been tested as a non-invasive system to detect different disease markers, such as acetone, ethanol and ammonia, related to the diagnosis and control of diabetes mellitus through exhaled breath. The sensors have been prepared by spin coating, achieving continuous sensitive layers at the surface of the SAW device. Low concentrations (5 ppm, 10 ppm and 25 ppm) of the marker analytes were measured, obtaining high sensitivities, good reproducibility, short time response and fast signal recovery.

Determination of refractive index, size, and concentration of nonabsorbing colloidal nanoparticles from measurements of the complex effective refractive index.

We describe a method for obtaining the refractive index (RI), size, and concentration of nonabsorbing nanoparticles in suspension from relatively simple optical measurements. The method requires measuring the complex effective RI of two dilute suspensions of the particles in liquids of different refractive indices. We describe the theoretical basis of the proposed method and provide experimental results validating the procedure.

Coherent reflection of light from a turbid suspension of particles in an internal-reflection configuration: Theory versus experiment.

We compare a recently developed coherent-scattering model for the reflectance of light from a turbid colloidal suspension of particles with experimental measurements. The experimental data were obtained in an internal reflection configuration around the critical angle using a glass prism in contact with a monodisperse colloidal suspension of latex particles, and a polydisperse suspension of TiO2 particles. First, we review the coherent scattering model and extend it to the case of polydisperse suspensions in an internal reflection configuration. The experimental data is then compared with results of the coherent scattering model and results obtained assuming that the colloidal system can be treated as a homogeneous medium with an effective index of refraction. We find that the experimental results are not compatible with the effective medium model. On the other hand, good fits to the experimental curves can be obtained with the coherent scattering model.

High-resolution optical angle sensors: approaching the diffraction limit to the sensitivity.

We carry out a detailed analysis of angle-sensitive devices based on the critical-angle effect. We consider their use in measuring small angular deflections of a laser beam. We establish the diffraction limit to the sensitivity for optical-angle sensors based on reflection and transmission of a laser beam. We find that this limit is identical to that of the triangulation scheme when using a position-sensitive detector or the autocollimation scheme. We analyze the main proposals to date of optical-angle sensors based on the critical-angle effect, focusing on their maximum sensitivity and their polarization dependence in practical conditions. We propose and analyze theoretically a novel and simple angle-sensitive device for sensing optical-beam deflections with very low polarization dependence and a maximum sensitivity close to the diffraction limit when used with typical laser beams. We discuss the basic principles for designing this type of device, provide numerical results, and point out a convenient fabrication procedure.

Technique for referencing of fiber-optic intensity-modulated sensors by use of counterpropagating signals.

We present a new all-optical fiber-referencing scheme for intensity-modulated sensors. It consists of a closed loop traversed by sensing and reference optical signals in opposite directions. With the proposed scheme the noise induced by power fluctuations of the optical source and mechanical perturbations can be greatly reduced. We experimentally demonstrate the efficiency of the scheme and discuss its use in a sensor array.