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1.
Sensors (Basel) ; 21(5)2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33668822

RESUMEN

Continuous hemodynamic monitoring is important for long-term cardiovascular healthcare, especially in hypertension. The impedance plethysmography (IPG) based carotid pulse sensing is a non-invasive diagnosis technique for measuring pulse signals and further evaluating the arterial conditions of the patient such as continuous blood pressure (BP) monitoring. To reach the high-resolution IPG-based carotid pulse detection for cardiovascular applications, this study provides an optimized measurement parameter in response to obvious pulsation from the carotid artery. The influence of the frequency of excitation current, electrode cross-sectional area, electrode arrangements, and physiological site of carotid arteries on IPG measurement resolution was thoroughly investigated for optimized parameters. In this study, the IPG system was implemented and installed on the subject's neck above the carotid artery to evaluate the measurement parameters. The measurement results within 6 subjects obtained the arterial impedance variation of 2137 mΩ using the optimized measurement conditions, including excitation frequency of 50 kHz, a smaller area of 2 cm2, electrode spacing of 4 cm and 1.7 cm for excitation and sensing functions, and location on the left side of the neck. The significance of this study demonstrates an optimized measurement methodology of IPG-based carotid pulse sensing that greatly improves the measurement quality in cardiovascular monitoring.


Asunto(s)
Determinación de la Presión Sanguínea , Análisis de la Onda del Pulso , Presión Sanguínea , Impedancia Eléctrica , Humanos , Pletismografía de Impedancia , Pulso Arterial
2.
Food Chem ; 352: 129402, 2021 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-33690074

RESUMEN

A non-thermal processing method was developed to promote preservation of brown rice using dielectric barrier discharge cold plasma (DBD-CP). Physicochemical properties including free fatty acid (FFA) content, surface color change, volatile organic components (VOCs) and flavor fingerprints were evaluated in brown rice submitted to DBD-CP. FFA levels were 25.2% lower in treated samples compared to the control, and a more stable surface color was obtained at the end of the storage period. A total of 35 major VOCs could be detected in treated samples, and reduced levels of hexanal can be used as an indicator of DBD-CP treatment in brown rice during storage. Moreover, the flavor fingerprints in DBD-CP treated groups can be successfully distinguished through headspace gas chromatography ion mobility spectrometry. Collectively, application of DBD-CP treatment could be utilized as a feasible approach to promote stabilization of brown rice and preserve flavor during storage.


Asunto(s)
Frío , Oryza/química , Gases em Plasma/química , Gusto , Impedancia Eléctrica , Compuestos Orgánicos Volátiles/análisis
3.
Sud Med Ekspert ; 64(2): 23-27, 2021.
Artículo en Ruso | MEDLINE | ID: mdl-33739064

RESUMEN

The purpose of this work is to establish the dynamics of the electrical conductivity of various corpse tissues using impedance measurements to assess this method for diagnosing the time of death. It was studied the values of the tissue impedance from the corpses of 8 persons of both sexes and different ages (30-50 years) who died from various causes, with the known date of death. A Keysight U1731 parting was used with two probes, which are stainless steel needles with a diameter of 0.5 mm and a 5 mm immersion length. The analysis of special literature on using indicators of the electrical conductivity dynamics of the corpse tissues, determined by the method of impedance measurement, in the early and late postmortem periods to diagnose the time of death. Trial measurements of a methodological nature were carried out with diagnostic zones: skin, cartilage tissue and tendon. The impedance-metric approach is promising for the purposes of forensic medical diagnostics of the time of death; however, it requires more careful experimental work to establish the dynamics of changes in the total electrical resistance of various tissues of a whole corpse over a long period from the moment of death.


Asunto(s)
Medicina Legal , Cambios Post Mortem , Autopsia , Cadáver , Impedancia Eléctrica , Femenino , Humanos , Masculino
4.
Anticancer Res ; 41(3): 1655-1662, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33788762

RESUMEN

BACKGROUND/AIM: Our previous study revealed the association between extracellular water-to-total body water ratio (ECW/TBW) and the therapeutic durability of chemotherapy and/or immune checkpoint inhibitors in advanced lung cancer. We retrospectively examined the usefulness of ECW/TBW in detecting frailty compared to other bioelectrical impedance (BIA) parameters in a larger number of patients. PATIENTS AND METHODS: Lung cancer patients underwent BIA before anti-cancer therapy at our hospital between June 1, 2018 and July 31, 2020. RESULTS: Of 99 patients, 26 were assigned to ECW/TBW≥0.4 (higher group: HG) and 57 to ECW/TBW<0.4 (lower group: LG). ECW/TBW increased significantly with performance deterioration and ageing. HG patients had significantly shorter time-to-treatment failure (TTF) than LG patients. In patients with performance status 0-1, those in the HG had shorter TTF than those in the LG. ECW/TBW was the only independent predictor of TTF according to multivariate analysis. CONCLUSION: ECW/TBW is an objective biomarker for detecting frailty among lung cancer patients.


Asunto(s)
Composición Corporal , Agua Corporal/metabolismo , Espacio Extracelular/metabolismo , Fragilidad/metabolismo , Neoplasias Pulmonares/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores , Impedancia Eléctrica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Insuficiencia del Tratamiento
5.
Molecules ; 26(4)2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33672029

RESUMEN

Exposure to reactive oxygen species can easily result in serious diseases, such as hyperproliferative skin disorders or skin cancer. Herbal extracts are widely used as antioxidant sources in different compositions. The importance of antioxidant therapy in inflammatory conditions has increased. Innovative formulations can be used to improve the effects of these phytopharmacons. The bioactive compounds of Plantago lanceolata (PL) possess different effects, such as anti-inflammatory, antioxidant, and bactericidal pharmacological effects. The objective of this study was to formulate novel liquid crystal (LC) compositions to protect Plantago lanceolata extract from hydrolysis and to improve its effect. Since safety is an important aspect of pharmaceutical formulations, the biological properties of applied excipients and blends were evaluated using assorted in vitro methods on HaCaT cells. According to the antecedent toxicity screening evaluation, three surfactants were selected (Gelucire 44/14, Labrasol, and Lauroglycol 90) for the formulation. The dissolution rate of PL from the PL-LC systems was evaluated using a Franz diffusion chamber apparatus. The antioxidant properties of the PL-LC systems were evaluated with 2,2-diphenyl-1-picrylhydrazyl (DPPH) and malondialdehyde (MDA) assessments. Our results suggest that these compositions use a nontraditional, rapid-permeation pathway for the delivery of drugs, as the applied penetration enhancers reversibly alter the barrier properties of the outer stratum corneum. These excipients can be safe and highly tolerable thus, they could improve the patient's experience and promote adherence.


Asunto(s)
Composición de Medicamentos , Cristales Líquidos/química , Extractos Vegetales/farmacología , Plantago/química , Piel/efectos de los fármacos , Compuestos de Bifenilo/química , Proliferación Celular/efectos de los fármacos , Proliferación Celular/efectos de la radiación , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Impedancia Eléctrica , Depuradores de Radicales Libres/farmacología , Humanos , Peroxidación de Lípido/efectos de los fármacos , Peroxidación de Lípido/efectos de la radiación , Malondialdehído/metabolismo , Permeabilidad , Picratos/química , Piel/efectos de la radiación , Rayos Ultravioleta
6.
Molecules ; 26(5)2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33652646

RESUMEN

Urine proteomic applications in children suggested their potential in discriminating between healthy subjects from those with respiratory diseases. The aim of the current study was to combine protein fractionation, by urinary extracellular vesicle isolation, and proteomics analysis in order to establish whether different patterns of respiratory impedance in healthy preschoolers can be characterized from a protein fingerprint. Twenty-one 3-5-yr-old healthy children, representative of 66 recruited subjects, were selected: 12 late preterm (LP) and 9 full-term (T) born. Children underwent measurement of respiratory impedance through Forced Oscillation Technique (FOT) and no significant differences between LP and T were found. Unbiased clustering, based on proteomic signatures, stratified three groups of children (A, B, C) with significantly different patterns of respiratory impedance, which was slightly worse in group A than in groups B and C. Six proteins (Tripeptidyl peptidase I (TPP1), Cubilin (CUBN), SerpinA4, SerpinF1, Thy-1 membrane glycoprotein (THY1) and Angiopoietin-related protein 2 (ANGPTL2)) were identified in order to type the membership of subjects to the three groups. The differential levels of the six proteins in groups A, B and C suggest that proteomic-based profiles of urinary fractionated exosomes could represent a link between respiratory impedance and underlying biological profiles in healthy preschool children.


Asunto(s)
Vesículas Extracelulares/genética , Proteoma/genética , Proteómica , Orina/química , Aminopeptidasas/orina , Proteínas Similares a la Angiopoyetina/orina , Preescolar , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/orina , Impedancia Eléctrica , Proteínas del Ojo/orina , Femenino , Humanos , Masculino , Factores de Crecimiento Nervioso/orina , Proteoma/química , Receptores de Superficie Celular/genética , Pruebas de Función Respiratoria , Serina Proteasas/orina , Serpinas/orina , Antígenos Thy-1/orina
7.
Clin Nutr ESPEN ; 42: 233-238, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33745585

RESUMEN

BACKGROUND: Paediatric Crohn's disease (CD) has been associated with undernutrition. Accurate and accessible measures of body composition would provide data to personalise nutritional therapy. We assessed feasibility of MRI-derived measures of psoas cross-sectional area (PCSA) in paediatric CD and correlated with anthropometric and bioelectrical impedance spectroscopy (BIS) measures. METHODS: MRI small bowel/pelvis images of patients with CD, aged <18 years, were retrieved. Patients with concurrent anthropometric and BIS measurements were eligible for inclusion. The PCSA at L3 was calculated by two assessors and combined. To assess reproducibility of measures we calculated the coefficient of variation (CoV). Age, height-Z-scores, weight-Z-scores and BIS measures were correlated with PCSA. Using normal paediatric data from CT-scans we derived psoas area Z-scores for our cohort. RESULTS: 10 patients were included. Mean age at MRI scan was 14.6 years (11.7-16.3). PCSA was calculated for all MRI scans. There was high reproducibility between measurers, mean CoV 0.099. There was a significant positive correlation between PCSA and BIA-derived fat free mass, Pearson correlation coefficient (PCC) 0.831, p = 0.003. Correlation coefficients for PCSA and Height-for-age Z-score, weight-for-age -Z-score and age were PCC 0.343- p = 0.33, PCC = 0.222- p = 0.54, and PCC 0.6034- p = 0.065, respectively. The mean PCSA Z-score was -1.81, with 70% of the patients having a Z-score < -2.0. CONCLUSIONS: These data demonstrate the feasibility of deriving measures of body composition from routine MRI imagine. There was significant positive correlation between PCSA and BIS-derived lean mass. Further studies are required to confirm applicability of normal ranges prior to routine clinical implementation.


Asunto(s)
Enfermedad de Crohn/diagnóstico por imagen , Espectroscopía Dieléctrica/métodos , Impedancia Eléctrica , Imagen por Resonancia Magnética/métodos , Músculos Psoas/diagnóstico por imagen , Adolescente , Antropometría/métodos , Composición Corporal , Peso Corporal , Niño , Femenino , Humanos , Masculino , Evaluación Nutricional , Pelvis , Reproducibilidad de los Resultados
8.
Biomed Eng Online ; 20(1): 29, 2021 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-33766044

RESUMEN

BACKGROUND: As an object's electrical passive property, the electrical conductivity is proportional to the mobility and concentration of charged carriers that reflect the brain micro-structures. The measured multi-b diffusion-weighted imaging (Mb-DWI) data by controlling the degree of applied diffusion weights can quantify the apparent mobility of water molecules within biological tissues. Without any external electrical stimulation, magnetic resonance electrical properties tomography (MREPT) techniques have successfully recovered the conductivity distribution at a Larmor-frequency. METHODS: This work provides a non-invasive method to decompose the high-frequency conductivity into the extracellular medium conductivity based on a two-compartment model using Mb-DWI. To separate the intra- and extracellular micro-structures from the recovered high-frequency conductivity, we include higher b-values DWI and apply the random decision forests to stably determine the micro-structural diffusion parameters. RESULTS: To demonstrate the proposed method, we conducted phantom and human experiments by comparing the results of reconstructed conductivity of extracellular medium and the conductivity in the intra-neurite and intra-cell body. The phantom and human experiments verify that the proposed method can recover the extracellular electrical properties from the high-frequency conductivity using a routine protocol sequence of MRI scan. CONCLUSION: We have proposed a method to decompose the electrical properties in the extracellular, intra-neurite, and soma compartments from the high-frequency conductivity map, reconstructed by solving the electro-magnetic equation with measured B1 phase signals.


Asunto(s)
Imagen de Difusión por Resonancia Magnética , Conductividad Eléctrica , Procesamiento de Imagen Asistido por Computador/métodos , Tomografía , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Mapeo Encefálico , Líquido Cefalorraquídeo , Impedancia Eléctrica , Humanos , Distribución Normal , Fantasmas de Imagen , Reproducibilidad de los Resultados
9.
Sensors (Basel) ; 21(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670691

RESUMEN

The development of biomedical devices benefits patients by offering real-time healthcare. In particular, pacemakers have gained a great deal of attention because they offer opportunities for monitoring the patient's vitals and biological statics in real time. One of the important factors in realizing real-time body-centric sensing is to establish a robust wireless communication link among the medical devices. In this paper, radio transmission and the optimal characteristics for impedance matching the medical telemetry of an implant are investigated. For radio transmission, an integral coupling formula based on 3D vector far-field patterns was firstly applied to compute the antenna coupling between two antennas placed inside and outside of the body. The formula provides the capability for computing the antenna coupling in the near-field and far-field region. In order to include the effects of human implantation, the far-field pattern was characterized taking into account a sphere enclosing an antenna made of human tissue. Furthermore, the characteristics of impedance matching inside the human body were studied by means of inherent wave impedances of electrical and magnetic dipoles. Here, we demonstrate that the implantation of a magnetic dipole is advantageous because it provides similar impedance characteristics to those of the human body.


Asunto(s)
Prótesis e Implantes , Telemetría , Impedancia Eléctrica , Electricidad , Humanos
10.
Sensors (Basel) ; 21(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670743

RESUMEN

A ruthenium oxide (RuOx) electrode was used to monitor contractile events of human pluripotent stem cells-derived cardiomyocytes (hPSC-CMs) through electrical impedance spectroscopy (EIS). Using RuOx electrodes presents an advantage over standard thin film Pt electrodes because the RuOx electrodes can also be used as electrochemical sensor for pH, O2, and nitric oxide, providing multisensory functionality with the same electrode. First, the EIS signal was validated in an optically transparent well-plate setup using Pt wire electrodes. This way, visual data could be recorded simultaneously. Frequency analyses of both EIS and the visual data revealed almost identical frequency components. This suggests both the EIS and visual data captured the similar events of the beating of (an area of) hPSC-CMs. Similar EIS measurement was then performed using the RuOx electrode, which yielded comparable signal and periodicity. This mode of operation adds to the versatility of the RuOx electrode's use in in vitro studies.


Asunto(s)
Electrodos , Miocitos Cardíacos , Óxidos , Rutenio , Impedancia Eléctrica , Humanos , Miocitos Cardíacos/fisiología
11.
Sensors (Basel) ; 21(4)2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33671996

RESUMEN

Organ-on-chip devices have provided the pharmaceutical and tissue engineering worlds much hope since they arrived and began to grow in sophistication. However, limitations for their applicability were soon realized as they lacked real-time monitoring and sensing capabilities. The users of these devices relied solely on endpoint analysis for the results of their tests, which created a chasm in the understanding of life between the lab the natural world. However, this gap is being bridged with sensors that are integrated into organ-on-chip devices. This review goes in-depth on different sensing methods, giving examples for various research on mechanical, electrical resistance, and bead-based sensors, and the prospects of each. Furthermore, the review covers works conducted that use specific sensors for oxygen, and various metabolites to characterize cellular behavior and response in real-time. Together, the outline of these works gives a thorough analysis of the design methodology and sophistication of the current sensor integrated organ-on-chips.


Asunto(s)
Dispositivos Laboratorio en un Chip , Impedancia Eléctrica , Análisis de Secuencia por Matrices de Oligonucleótidos
12.
Sensors (Basel) ; 21(4)2021 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-33670022

RESUMEN

Conventional pathogenic bacteria-detection methods are lab-bound, time-consuming and need trained personnel. Microelectrodes can be used to recognize harmful microorganisms by dielectric impedance spectroscopy. However, crucial for this spectroscopy method are the spatial dimensions and layout of the electrodes, as the corresponding distribution of the electric field defines the sensor system parameters such as sensitivity, SNR, and dynamic range. Therefore, a variety of sensor models are created and evaluated. FEM simulations in 2D and 3D are conducted for this impedimetric sensor. The authors tested differently shaped structures, verified the linear influence of the excitation amplitude and developed a mathematical concept for a quality factor that practically allows us to distinguish arbitrary sensor designs and layouts. The effect of guard electrodes blocking outer influences on the electric field are investigated, and essential configurations are explored. The results lead to optimized electronic sensors in terms of geometrical dimensions. Possible material choices for real sensors as well as design and layout recommendations are presented.


Asunto(s)
Bacterias/aislamiento & purificación , Técnicas Biosensibles , Espectroscopía Dieléctrica , Microelectrodos , Impedancia Eléctrica
13.
Sensors (Basel) ; 21(4)2021 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-33670072

RESUMEN

A quantitative and rapid burn injury detection method has been proposed based on the electrical impedance spectroscopy (EIS) of blood with a seven-parameter equivalent circuit. The degree of burn injury is estimated from the electrical impedance characteristics of blood with different volume proportions of red blood cells (RBCs) and heated red blood cells (HRBCs). A quantitative relationship between the volume portion HHCT of HRBCs and the electrical impedance characteristics of blood has been demonstrated. A seven -parameter equivalent circuit is employed to quantify the relationship from the perspective of electricity. Additionally, the traditional Hanai equation has been modified to verify the experimental results. Results show that the imaginary part of impedance ZImt under the characteristic frequency (fc) has a linear relationship with HHCT which could be described by ZImt = -2.56HHCT - 2.01 with a correlation coefficient of 0.96. Moreover, the relationship between the plasma resistance Rp and HHCT is obtained as Rp = -7.2HHCT + 3.91 with a correlation coefficient of 0.96 from the seven -parameter equivalent circuit. This study shows the feasibility of EIS in the quantitative detection of burn injury by the quantitative parameters ZImt and Rp, which might be meaningful for the follow-up clinical treatment for burn injury.


Asunto(s)
Quemaduras , Espectroscopía Dieléctrica , Impedancia Eléctrica , Quemaduras/diagnóstico , Eritrocitos , Humanos
14.
Int J Mol Sci ; 22(4)2021 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-33669494

RESUMEN

Campylobacter concisus is a human-pathogenic bacterium of the gastrointestinal tract. This study aimed at the contribution of the mucosal immune system in the context of intestinal epithelial barrier dysfunction induced by C. concisus. As an experimental leaky gut model, we used in vitro co-cultures of colonic epithelial cell monolayers (HT-29/B6-GR/MR) with M1-macrophage-like THP-1 cells on the basal side. Forty-eight hours after C. concisus infection, the decrease in the transepithelial electrical resistance in cell monolayers was more pronounced in co-culture condition and 22 ± 2% (p < 0.001) higher than the monoculture condition without THP-1 cells. Concomitantly, we observed a reduction in the expression of the tight junction proteins occludin and tricellulin. We also detected a profound increase in 4 kDa FITC-dextran permeability in C. concisus-infected cell monolayers only in co-culture conditions. This is explained by loss of tricellulin from tricellular tight junctions (tTJs) after C. concisus infection. As an underlying mechanism, we observed an inflammatory response after C. concisus infection through pro-inflammatory cytokines (TNF-α, IL-1ß, and IL-6) released from THP-1 cells in the co-culture condition. In conclusion, the activation of subepithelial immune cells exacerbates colonic epithelial barrier dysfunction by C. concisus through tricellulin disruption in tTJs, leading to increased antigen permeability (leaky gut concept).


Asunto(s)
Campylobacter/inmunología , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Apoptosis , Línea Celular , Supervivencia Celular , Técnicas de Cocultivo , Impedancia Eléctrica , Células Epiteliales/patología , Humanos , Inflamación/patología , Intestinos/microbiología , Intestinos/patología , Macrófagos/metabolismo , Modelos Biológicos , Ocludina/metabolismo , Fracciones Subcelulares/metabolismo , Uniones Estrechas/metabolismo
15.
J Vis Exp ; (168)2021 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-33720120

RESUMEN

The early interactions between the nasal epithelial layer and the innate immune cells during viral infections remains an under-explored area. The significance of innate immunity signaling in viral infections has increased substantially as patients with respiratory infections who exhibit high innate T cell activation show a better disease outcome. Hence, dissecting these early innate immune interactions allows the elucidation of the processes that govern them and may facilitate the development of potential therapeutic targets and strategies for dampening or even preventing early progression of viral infections. This protocol details a versatile model that can be used to study early crosstalk, interactions, and activation of innate immune cells from factors secreted by virally infected airway epithelial cells. Using an H3N2 influenza virus (A/Aichi/2/1968) as the representative virus model, innate cell activation of co-cultured peripheral blood mononuclear cells (PBMCs) has been analyzed using flow cytometry to investigate the subsets of cells that are activated by the soluble factors released from the epithelium in response to the viral infection. The results demonstrate the gating strategy for differentiating the subsets of cells and reveal the clear differences between the activated populations of PBMCs and their crosstalk with the control and infected epithelium. The activated subsets can then be further analyzed to determine their functions as well as molecular changes specific to the cells. Findings from such a crosstalk investigation may uncover factors that are important for the activation of vital innate cell populations, which are beneficial in controlling and suppressing the progression of viral infection. Furthermore, these factors can be universally applied to different viral diseases, especially to newly emerging viruses, to dampen the impact of such viruses when they first circulate in naïve human populations.


Asunto(s)
Inmunidad Innata , Subtipo H3N2 del Virus de la Influenza A/inmunología , Gripe Humana/inmunología , Gripe Humana/virología , Modelos Biológicos , Células 3T3 , Animales , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Técnicas de Cocultivo , Impedancia Eléctrica , Células Epiteliales/efectos de los fármacos , Células Epiteliales/inmunología , Células Nutrientes/citología , Humanos , Subtipo H3N2 del Virus de la Influenza A/efectos de los fármacos , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/virología , Ratones , Mitomicina/farmacología , Mucina 5AC/metabolismo , Mucosa Nasal/patología , Tubulina (Proteína)/metabolismo
16.
Sensors (Basel) ; 21(5)2021 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-33668250

RESUMEN

Textile electrodes, also called textrodes, for biosignal monitoring as well as electrostimulation are central for the emerging research field of smart textiles. However, so far, only the general suitability of textrodes for those areas was investigated, while the influencing parameters on the contact impedance related to the electrode construction and external factors remain rather unknown. Therefore, in this work, six different knitted electrodes, applied both wet and dry, were compared regarding the influence of specific knitting construction parameters on the three-electrode contact impedance measured on a human forearm. Additionally, the influence of applying pressure was investigated in a two-electrode setup using a water-based agar dummy. Further, simulation of an equivalent circuit was used for quantitative evaluation. Indications were found that the preferred electrode construction to achieve the lowest contact impedance includes a square shaped electrode, knitted with a high yarn density and, in the case of dry electrodes, an uneven surface topography consisting of loops, while in wet condition a smooth surface is favorable. Wet electrodes are showing a greatly reduced contact impedance and are therefore to be preferred over dry ones; however, opportunities are seen for improving the electrode performance of dry electrodes by applying pressure to the system, thereby avoiding disadvantages of wet electrodes with fluid administration, drying-out of the electrolyte, and discomfort arising from a "wet feeling".


Asunto(s)
Electrodos , Piel , Textiles , Impedancia Eléctrica , Diseño de Equipo , Humanos
17.
J Vis Exp ; (168)2021 02 10.
Artículo en Inglés | MEDLINE | ID: mdl-33645569

RESUMEN

Eye disorders affect millions of people worldwide, but the limited availability of human tissues hinders their study. Mouse models are powerful tools to understand the pathophysiology of ocular diseases because of their similarities with human anatomy and physiology. Alterations in the retinal pigment epithelium (RPE), including changes in morphology and function, are common features shared by many ocular disorders. However, successful isolation and culture of primary mouse RPE cells is very challenging. This paper is an updated audiovisual version of the protocol previously published by Fernandez-Godino et al. in 2016 to efficiently isolate and culture primary mouse RPE cells. This method is highly reproducible and results in robust cultures of highly polarized and pigmented RPE monolayers that can be maintained for several weeks on Transwells. This model opens new avenues for the study of the molecular and cellular mechanisms underlying eye diseases. Moreover, it provides a platform to test therapeutic approaches that can be used to treat important eye diseases with unmet medical needs, including inherited retinal disorders and macular degenerations.


Asunto(s)
Disección , Cultivo Primario de Células/métodos , Epitelio Pigmentado de la Retina/citología , Animales , Bioensayo , Diferenciación Celular , Polaridad Celular , Separación Celular , Impedancia Eléctrica , Células Epiteliales/citología , Humanos , Ratones Endogámicos C57BL , Fagocitosis , Factores de Tiempo
18.
Animal ; 15(3): 100156, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33573950

RESUMEN

The ability to accurately estimate fat mass and fat-free mass (FFM) has the potential to improve the way in which sow body condition can be managed in a breeding herd. Bioelectrical impedance spectroscopy (BIS) has been evaluated as a practical technique for assessment of body composition in several livestock species, but similar work is lacking in sows. Bioelectrical impedance uses population-specific algorithms that require values for the apparent resistivities of body fluids and body proportion factors. This study comprised three major aims: (i) to derive apparent resistivity coefficients for extracellular water (ECW) and intracellular water (ICW) required for validation of BIS predictions of total body water (TBW) in live sows against standard reference tracer dilution methods; (ii) to develop predictions of TBW to body composition prediction algorithms, namely FFM, by developing a body geometry correction factor (Kb) and (iii) to compare the BIS predictions of FFM against existing impedance predictors and published prediction equations for use in sows, based on physical measurements of back-fat depth and BW (P2-based predictors). Whole body impedance measurements and the determination of TBW by deuterium dilution and ECW by bromide dilution were performed on 40 Large White x Landrace sows. Mean apparent resistivity coefficients of body fluids were 431.1 Ω.cm for ECW and 1827.8 Ω.cm for ICW. Using these coefficients, TBW and ECW were over-estimated by 6.5 and 3.3%, respectively, compared to measured reference values, although these differences were not statistically different (P > 0.05). Mean Kb was 1.09 ±â€¯0.14. Fat-free mass predictions were 194.9 kg, which equates to 60.9% of total sow weight, and 183.0 kg for BIS and the deuterium dilution method, respectively. Mean differences between the predicted and measured FFM values ranged from -8.2 to 32.7%, but were not statistically different (P > 0.05). Method validation (leave-one-out procedure) revealed that mean differences between predicted and measured values were not statistically significant (P > 0.05). Of the impedance-based predictors, equivalence testing revealed that BIS displayed the lowest test bias of 11.9 kg (8.2%), although the P2-based prediction equations exhibited the lowest bias and percentage equivalence, with narrow limits of agreement. Results indicate although differences between mean predicted and measured values were not significantly different, relatively wide limits of agreement suggest BIS as an impractical option for assessing body composition in individual sows compared to the use of existing prediction equations based on BW and back fat.


Asunto(s)
Composición Corporal , Agua Corporal , Animales , Impedancia Eléctrica , Femenino , Técnicas de Dilución del Indicador/veterinaria , Análisis Espectral/veterinaria , Porcinos
19.
Medicine (Baltimore) ; 100(4): e23722, 2021 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-33530173

RESUMEN

ABSTRACT: Segmental multi-frequency bioelectrical impedance analysis (s-MFBIA) has been adopted recently to evaluate the volume of breast cancer-related lymphedema (BCRL). This procedure uses the segmental phase angle (s-PhA) as an indicator of cellular integrity. In the smaller-built Asian population, the BCRL often has a small volume difference and can be overlooked by tape circumference volume measurement (TVM). This study aimed to investigate the clinical feasibility of s-MFBIA for the assessment of lymphedema severity compared with TVM and evaluate the association between lymphedema severity and cellular integrity of the affected arm based on s-PhA values for a patient with mild- to moderate-degree BCRL.Segmental PhA and extracellular water (ECW)/total body water (TBW) ratio of bilateral arms were measured using InBody S10, an s-MFBIA device, in 128 BCRL patients. Inter-limb volume ratio was measured using TVM. The inter-limb ECW/TBW ratio was correlated with inter-limb volume ratio. Inter-limb ECW/TBW ratio and inter-limb volume ratio were then correlated with inter-limb PhA ratio to demonstrate the association between lymphedema severity and arm cellular integrity.The inter-limb ECW/TBW ratio and inter-limb volume ratio were positively correlated (r = 0.654, P < .001). The same result was obtained after adjusting for age, body mass index, postoperative survival, and duration of lymphedema (r = 0.636, 0.653, 0.652, and 0.648, P < .001). The inter-limb PhA ratio demonstrated significant negative correlation with inter-limb ECW/TBW ratio and inter-limb volume ratio (r = -0.896, -0.562, P < .001).s-MFBIA has high consistency with the conventional TVM method, and its relation to cellular integrity by segmental PhA enables better understanding of the cellular state of the affected limb in mild- to moderate-degree BCRL. Therefore, it is clinically feasible for severity assessment and monitoring of mild- to moderate-degree BCRL in smaller-built Asian patients.


Asunto(s)
Brazo/patología , Linfedema del Cáncer de Mama/patología , Impedancia Eléctrica , Adulto , Grupo de Ascendencia Continental Asiática , Índice de Masa Corporal , Estudios de Factibilidad , Femenino , Humanos , Persona de Mediana Edad , Índice de Severidad de la Enfermedad
20.
Nutr. hosp ; 38(1): 94-99, ene.-feb. 2021. tab
Artículo en Inglés | IBECS | ID: ibc-198845

RESUMEN

INTRODUCTION: body fat reflects important clinical impacts among hemodialysis patients; thus, simple and safe methods are required for a careful evaluation of this body compartment. OBJECTIVES: to evaluate the concordance of estimates of total body fat percentage (%BF), calculated using bioelectrical impedance analysis (BIA) and sum of four skinfolds (SSKD) measures, with those obtained using dual-energy X-ray absorptiometry (DEXA) in patients with chronic kidney disease (CKD) receiving hemodialysis. METHODS: a cross-sectional study was conducted in 317 patients undergoing hemodialysis. The %BF was evaluated using BIA, SSKD measurement, and DEXA, and stratified by sex and tertiles. The Wilcoxon test for paired samples was used to compare the %BF obtained using the different methods, and Lin's concordance correlation coefficient (CCC-L) to evaluate concordance. RESULTS: the average %BF estimated using DEXA was 29.3 ± 9.3 %, with significant differences among the three methods (p < 0.05). SSKD measurement presented a higher CCC-L concordance with DEXA, regardless of sex. After stratification of the sample in tertiles, BIA presented a higher CCC-L concordance with DEXA among the patients with CKD with a %BF above 34.4 % (third tertile). Conversely, SSKD measurement presented better concordance with DEXA for those with a %BF equal to or less than 34.4 %. CONCLUSIONS: in terms of the estimates of the %BF, SSKD measurement displayed a better concordance with DEXA


INTRODUCCIÓN: la grasa corporal refleja importantes impactos clínicos entre los pacientes en hemodiálisis; por lo tanto, se requieren métodos simples y seguros para una evaluación cuidadosa de este compartimiento del cuerpo. OBJETIVOS: evaluar la concordancia de las estimaciones del porcentaje de grasa corporal total (%GC), calculadas mediante el análisis de impedancia bioeléctrica (BIA) y la suma de las medidas de cuatro pliegues cutáneos (CPC), con las obtenidas mediante absorciometría dual energética de rayos X (DEXA) en pacientes con enfermedad renal crónica (ERC) que reciben hemodiálisis. MÉTODOS: se realizó un estudio transversal en 317 pacientes en hemodiálisis. La %GC se evaluó mediante BIA, medición de CPC y DEXA, y se estratificó por sexos y terciles. Se utilizó la prueba de Wilcoxon para muestras pareadas para comparar los %GC obtenidos con los diferentes métodos, y el coeficiente de correlación de concordancia de Lin (CCC-L) para evaluar la concordancia. RESULTADOS: el %GC promedio estimado usando DEXA fue del 29,3 ± 9,3 %, con diferencias significativas entre los tres métodos (p < 0,05). La medición de los CPC presentó una mayor concordancia de CCC-L con DEXA, independientemente del sexo. Tras la estratificación de la muestra en terciles, la BIA presentó una mayor concordancia de CCC-L con DEXA entre los pacientes con ERC con un %GC superior al 34,4 % (tercer tercil). Por el contrario, la medición de los CPC presentó una mejor concordancia con la DEXA para aquellos con un %GC igual o inferior al 34,4 %. CONCLUSIÓN: en términos de las estimaciones del %GC, la medición de los CPC mostró una mejor concordancia con la DEXA


Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Grosor de los Pliegues Cutáneos , Enfermedades Renales/complicaciones , Enfermedades Renales/dietoterapia , Diálisis Renal/métodos , Evaluación Nutricional , Impedancia Eléctrica , Absorciometría de Fotón , Estudios Transversales
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