Spelling suggestions: "subject:"bioimpedance"" "subject:"bioimpedances""
81 |
Možnosti ovlivnění svalové hypertrofie u mužů ve věku 20-25 let ve fitnes centru / Options affect muscle hypertrophy in men age 20 25 years in the fitness centreCeman, Martin January 2011 (has links)
Title: Options affect muscle hypertrophy in men age 20 25 years in the fitness centre. Method: Laboratory evaluation of body composition (bioelectric Impedance Analysis) and anthropometric measurement of muscle mass. Results: H1 Volumetric training significantly increased body weight, H2, passing the volume of training significantly increased muscle groups of districts reporting, H3 After completing training, the volume change of FM and FFM in the same order of magnitude ratio - 2:1. H4 After completing the training volume ratio of ECM:BCM linear placements the same as during the initial measurement). The proposed program increased the total weight of 8.9 kg. Similarly, the districts reporting increased body parts. Expected FM:FFM was higher than expected. H1, H2 and H4 is confirmed. Keywords: Volume training, 20 men 25 years, bioimpedences, body composition, fitness centre, hypertrophy Objective: The aim of this work is to create individual training macrocycles. Theme on volume training in the fitness centre. This volume training plan aims to increase the growth of active muscle mass and muscle mass.
|
82 |
CellMap: An Automated Multielectrode Array Cell Culture Analysis System Based on Electrochemical Impedance SpectroscopyAbdur Rahman, Abdur Rub 28 June 2007 (has links)
The objective of this research is to develop fundamental understanding of cell-substrate (CS) and cell-cell (CC) interactions in the culture space for time evolving cell cultures. Space resolved CC and CS interactions are important indicators of cell-density distribution, localized cellular behavior, and multiple cell-layers which are differentiators of normal and abnormal cell behavior. In this research, CS and CC interactions and the variations therein due to a) Cell growth, 2) cell-drug interaction, and 3) effect of Cytotoxin were studied using multielectrode, multi-frequency Electrochemical Impedance Spectroscopy (EIS). Contemporary impedance based methods sense either CC or CS interaction as a space averaged macroscopic quantity. A major contribution of this research is that, both CC and CS interactions are recorded and analyzed with spatio-temporal resolution. This research led to the development of an automated cell culture monitoring system, namely, CellMap.
A planar eight electrode sensor was fabricated on a glass substrate and interfaced with a switching circuit. The switching circuit sequentially selects consecutive electrodes upon input of a 5V trigger pulse which is generated by the frequency response analyzer at the end of each frequency scan, thereby facilitating automated switching and recording of multielectrode dataset. Calibration standards and protocols were developed to null the channel parasitics of individual channels. A set of eight impedance measurements for eight electrodes constitutes a "frame". Frames are recorded at regular time intervals over the desired course of time.
Impedance mapping of adhesion, spreading, motility and detachment of OvCa429 ovarian cancer cells was performed over a period of 70 hours. The cell-layer resistance, which indicates cell-cell contact, increased as a function of time until confluence, and decreased thereafter due to cell death and detachment. This was also confirmed by optical microscopy observations. Similarly, the cell layer Constant Phase Element (CPE) parameters, which were found to correlate well with cell density distribution, also increased as a function of time until confluence and decreased thereafter. Additionally, the cell-growth mapping revealed that the CellMap system is able to resolve non-uniform cell distributions in the culture space, which may be useful in differentiating between normal and pathological cells.
|
83 |
Composição corporal em pacientes com doença inflamatória intestinal: antropometria versus bioimpedância / Body composition of patients with inflamatory bowel disease: antropometry versus bioimpedanceViviane Abrantes Jardim 25 March 2013 (has links)
A Doença Inflamatória Intestinal (DII) é uma desordem caracterizada pela inflamação difusa do trato gastrointestinal. Os dois principais tipos de DII são a Retocolite Ulcerativa (RCU) e a Doença de Crohn (DC) e ambas cursam com alterações no estado nutricional (EN). O objetivo deste estudo foi comparar a composição corporal, obtida por meio de diferentes métodos, em pacientes com DC e RCU em atendimento ambulatorial, avaliando possíveis diferenças nos grupos de doentes entre si e quando comparados a indivíduos saudáveis. Foi realizado um estudo transversal incluindo 101 pacientes com DII, sendo 50 com DC (GDC) e 51 com RCU (GRCU), além de 35 indivíduos saudáveis (GCON), selecionados no Ambulatório do Hospital Universitário Pedro Ernesto (HUPE) da Universidade do Estado do Rio de Janeiro (UERJ). Informações sócio-demográficas e pessoais, como prática de exercício físico, tabagismo, doenças pregressas e procedimentos cirúrgicos prévios foram coletadas. A avaliação antropométrica consistiu de: peso; altura; circunferências do braço, da cintura e do quadril; circunferência muscular do braço (CMB) e pregas cutâneas do tríceps, bíceps, peitoral, axilar, subescapular, suprailíaca, supraespinhal, abdominal, perna e coxa. O percentual de gordura corporal (% GC) foi estimado a partir de equações que utilizam o somatório de pregas cutâneas e por meio de bioimpedância elétrica (BIA). Para estimar o percentual de gordura subcutânea foi utilizado o somatório de dez dobras. As variáveis laboratoriais analisadas foram: hemograma completo, proteínas totais, albumina, globulina, velocidade de hemossedimentação e proteína C reativa. As análises estatísticas foram realizadas utilizando-se o software STATA versão 10.0. A classificação do EN, por meio do índice de massa corporal (IMC), evidenciou baixa prevalência de desnutrição nos três grupos avaliados. Ao analisar diretamente as medidas antropométricas de peso e IMC, observou-se que os pacientes com DC apresentaram valores significativamente menores do que os indivíduos do grupo controle. A avaliação da CMB mostrou que os pacientes do GDC e GRCU apresentaram depleção de massa magra em comparação aos indivíduos do GCON, porém sem apresentar diferenças entre os dois grupos de pacientes com DII. Em relação ao %GC obtido por BIA não foram verificadas diferenças entre os três grupos de estudo. Ao se verificar o %GC com a utilização das fórmulas de Peterson, Durnin & Womersley e Jackson & Pollock (que utiliza o somatório de três dobras) observou-se que os pacientes com DC apresentaram tecido adiposo significativamente depletado em relação aos indivíduos do GCON e do GRCU. Ao compararmos os %GC obtidos por diferentes métodos de estimativa, observou-se que as equações de Jackson & Pollock (que utilizam o somatório de três e sete dobras) apresentaram resultados significativamente menores quando comparados aos das equações de Peterson e Durnin & Womersley, nos dois grupos de pacientes. Os níveis séricos de proteínas totais e albumina, e a contagem total de hemácias foram menores nos indivíduos com DC quando comparados aos indivíduos do grupo controle e/ou aos indivíduos do grupo com RCU. Os pacientes com DC apresentaram comprometimento importante do EN em comparação aos pacientes com RCU e, notadamente, em relação aos indivíduos saudáveis. / Inflammatory Bowel Disease (IBD) is a disorder characterized by diffuse inflammation of the gastrointestinal tract. The two main types of IBD are ulcerative colitis (UC) and Crohn's disease (CD), both coursing with changes in nutritional status (NS). The objective of this study was to investigate the existence of associations between body composition measured by electrical bioimpedance (BIA) and by the equations used for the estimate of fat percent in patients with CD and UC on ambulatory treatment and when compared to healthy individuals. A cross-sectional study was conducted on 101 patients with IBD, 50 of them with CD (GCD) and 51 with UC (GUC), and on 35 healthy subjects (GCON), selected at the Ambulatory of Pedro Ernesto University Hospital (HUPE) of the Rio de Janeiro State University (UERJ). Sociodemographic information such as practice of physical activity, smoking habit, previous diseases and surgical procedures was collected. Anthropometric evaluation consisted of weight; height; arm, waist and hip circumferences; arm muscle circumference (AMC), and the following skin folds: triceps, biceps, pectoral, axillary, subscapular, suprailiac, supraspinal, abdominal, leg, and thigh. Percent body fat (%BF) was estimated using equations based on the sum of skin folds and by BIA. Percent subcutaneous fat was estimated as the sum of ten folds. The laboratory variables analyzed, included: complete blood count, total protein, albumin, globulin, erythrocyte sedimentation rate, and C-reactive protein. Data were analyzed statistically using the STATA software, version 10.0. Classification of NS based on body mass index (BMI) revealed a low prevalence of malnutrition in the groups evaluated. Direct analysis of weight and BMI measurements revealed that patients with CD had significantly lower values than GCON individuals. The evaluation of AMC showed that GCD and GUC patients had depleted lean mass compared to GCON individuals, with no difference between the two groups of patients with IBD. No differences in %BF determined by BIA were detected among the three study groups. When %BF was determined using the formulas of Peterson, Durnin & Womersley and Jackson & Pollock (which use the sum of three folds), patients with CD were found to have significantly depleted adipose tissue compared to GCON and GUC individuals. Comparison of %BF values obtained by different estimate methods showed that the equations of Jackson & Pollock (which use the sum of three and seven folds) yielded significantly lower results than the equations of Peterson and Durnin & Womersley for the two patient groups. Seric levels of total protein and albumin, as well as red blood cell count and relative count of lymphocytes were lower in the individuals with CD than the individuals of the control group and/or the patients with UC. Patients with CD showed significant involvement of NS compared to patients with UC and especially compared to healthy individuals.
|
84 |
Volnočasové aktivity a motorická výkonnost u dětí staršího školního věku / Leisure time activities and motor performance among school aged childrenBohata, Pavel January 2018 (has links)
Title: Leisure time activities and motor performance among school aged children Objectives: The aim of the thesis is to evaluate a level of motor performance and leisure time activities among school children aged 12 - 14 years, on elementary school Boženy Němcové in Litoměřice. We want to know, if students with extended teaching of music and aesthetics will get worse results compared to students without extended teaching. Methods: Study presents empirical quantitative research and 86 students participate in it. Level of motor performance was determined by the test battery called Unifittest 6 - 60 and structure of leisure time activities was monitored by the part of the sociological questionnaire called COMPASS II. Amount of substucaneous fat was measured by the multifrequency bioelectrical impedance analysis (BIA). We werified our hypotheses by the two sample t-test and with coefficient of effect size Cohens'd. Results: On the basis of evaluated results the statistically signifiant diference was not found in all hypotheses between comparator groups with level of significance (p ≤ 0,05). Cohens'd proved only small or no effect size, except for girls in Leger test where we proved medium effect size (d = 0,5). There wasn't signifiant diference in the structure of leisure time activities. Key words:...
|
85 |
Validace multikanálové bioimpedance cév za použití synchronizované cévní sonografie / Validaton of multichannel bioimpedance of vessels using synchronized vascular ultrasonographyHidegová, Simona January 2021 (has links)
The inclusion of a new device in clinical practice requires an adequate validation. The original publication which introduced multichannel bioimpedance monitor MBM was focused on discribing its technical parameters and demonstration measurements. Further evaluation desires comparision with other standard measuring device. This thesis describes pulse wave measurement by MBM and by other medical devices used for establishing cardiovascular risk. It proposes the validation experiment with synchronized vascular ultrasonography as a reference method. The process of the experimental measurement, aquired data and following data analysis are described in detail. The outputs of the experiment are statistically evaluated. The MBM’s performance and design of the experiment are discussed.
|
86 |
Multiscale Modeling and Analysis of X-ray Windows, Microcantilevers, and Bioimpedance MicroelectrodesLarsen, Kyle Grant 09 August 2022 (has links)
X-ray detector windows must be thin enough to transmit sufficient low-energy x-rays, yet strong enough to withstand up to an atmosphere of differential pressure. Traditional low-energy x-ray windows consist of a support layer and pressure membrane spanning that support. Numerical modeling of several x-ray windows was used to show that both low- and high-energy x-ray transmission can be improved by adding a secondary support structure. Finite element analysis of the x-ray window models showed that the stress from a typical applied load does not exceed the ultimate strength or yield strength of the respective materials. The specific x-ray window models developed in this work may serve as a foundation for improving commercial windows, especially those geared toward low-energy transmission. For local mechanical film testing, microcantilevers were cut in suspended many-layer graphene using a focused ion beam. Multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler-Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force-deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 GPa and 12 GPa, respectively. The multipoint force-deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled. Bioimpedance can be measured by applying a known current to the tissue through two (current carrying) electrodes and recording the resulting voltage on two different (pickup) electrodes. Bioimpedance has been used to detect heart rate, respiration rate, blood pressure, and blood glucose. A wrist-based wearable bioimpedance device can measure heart rate by detecting the minute impedance changes caused by the modulation of blood volume in the radial artery. Using finite element analysis, I modeled how electrode position affects sensitivity to pulsatile changes. The highest sensitivity was found to occur when the pickup electrodes were centered over the artery. In this work, we used microfabricated carbon infiltrated-carbon nanotube electrodes to measure the change in contact bioimpedance for dry electrodes, and identical electrodes with a wet electrolyte, on five human subjects in the range of 1 kHz to 100 kHz. We found that the acclimated skin-electrode impedance of the dry electrodes approached that of the wet electrodes, especially for electrodes with larger areas. We also found that the acclimation time does not appear to depend on electrode area or frequency. The skin-electrode impedance after acclimation does depend on electrode area and frequency, decreasing with both. This work shows that if care is taken during the acclimation period, then dry carbon composite electrodes can be used in bioimpedance wearable applications.
|
87 |
Irreversible Electroporation Therapy for the Treatment of Spontaneous Tumors in Cancer PatientsNeal II, Robert Evans 04 January 2012 (has links)
Irreversible electroporation is a minimally invasive technique for the non-thermal destruction of cells in a targeted volume of tissue, using brief electric pulses, (~100 µs long) delivered through electrodes placed into or around the targeted region. These electric pulses destabilize the integrity of the cell membrane, resulting in the creation of nanoscale defects that increase a cell’s permeability to exchange with its environment. When the energy of the pulses is high enough, the cell cannot recover from these effects and dies in a non-thermal manner that does not damage neighboring structures, including the extracellular matrix. IRE has been shown to spare the major vasculature, myelin sheaths, and other supporting tissues, permitting its use in proximity to these vital structures. This technique has been proposed to be harnessed as an advantageous non-thermal focal ablation technique for diseased tissues, including tumors.
IRE electric pulses may be delivered through small (ø ≈ 1 mm) needle electrodes, making treatments minimally invasive and easy to apply. There is sub-millimeter demarcation between treated and unaffected cells, which may be correlated with the electric field to which the tissue is exposed, enabling numerical predictions to facilitate treatment planning. Immediate changes in the cellular and tissue structure allow real-time monitoring of affected volumes with imaging techniques such as computed tomography, magnetic resonance imaging, electrical impedance tomography, or ultrasound. The ability to kill tumor cells has been shown to be independent of a functioning immune system, though an immune response seems to be promoted by the ablation. Treatments are unaltered by blood flow and the electric pulses may be administered quickly (~ 5 min).
Recently, safety and case studies using IRE for tumor therapy in animal and human patients have shown promising results. Apart from these new studies, previous work with IRE has involved studies in healthy tissues and small cutaneous experimental tumors. As a result, there remain significant differences that must be considered when translating this ablation technique towards a successful and reliable therapeutic option for patients. The dissertation work presented here is designed to develop irreversible electroporation into a robust, clinically viable treatment modality for targeted regions of diseased tissue, with an emphasis on tumors. This includes examining and creating proving the efficacy for IRE therapy when presented with the many complexities that present themselves in real-world clinical patient therapies, including heterogeneous environments, large and irregular tumor geometries, and dynamic tissue properties resulting from treatment. The impact of these factors were theoretically tested using preliminary in vitro work and numerical modeling to determine the feasibility of IRE therapy in heterogeneous systems. The feasibility of use was validated in vivo with the successful treatment of human mammary carcinomas orthotopically implanted in the mammary fat pad of mice using a simple, single needle electrode design easily translatable to clinical environments.
Following preliminary theoretical and experimental work, this dissertation considers the most effective and accurate treatment planning strategies for developing optimal therapeutic outcomes. It also experimentally characterizes the dynamic changes in tissue properties that result from the effects of IRE therapy using ex vivo porcine renal cortical tissue and incorporates these into a revised treatment planning model. The ability to use the developments from this earlier work is empirically tested in the treatment of a large sarcoma in a canine patient that was surgically unresectable due to its proximity to critical arteries and the sciatic nerve. The tumor was a large and irregular shape, located in a heterogeneous environment. Treatment planning was performed and the therapy carried out, ultimately resulting in the patient being in complete remission for 14 months at the time of composing this work.
The work presented in this dissertation finishes by examining potential supplements to enhance IRE therapy, including the presence of an inherent tumor-specific patient immune response and the addition of adjuvant therapeutic modalities. / Ph. D.
|
88 |
Bioimpedance spectroscopy of breast cancer cells: A microsystems approachSrinivasaraghavan, Vaishnavi 04 November 2015 (has links)
Bioimpedance presents a versatile, label-free means of monitoring biological cells and their responses to physical, chemical and biological stimuli. Breast cancer is the second most common type of cancer among women in the United States. Although significant progress has been made in diagnosis and treatment of this disease, there is a need for robust, easy-to-use technologies that can be used for the identification and discrimination of critical subtypes of breast cancer in biopsies obtained from patients. This dissertation makes contributions in three major areas towards addressing the goal. First, we developed miniaturized bioimpedance sensors using MEMS and microfluidics technology that have the requisite traits for clinical use including reliability, ease-of-use, low-cost and disposability. Here, we designed and fabricated two types of bioimpedance sensors. One was based on electric cell-substrate impedance sensing (ECIS) to monitor cell adhesion based events and the other was a microfluidic device with integrated microelectrodes to examine the biophysical properties of single cells. Second, we examined a panel of triple negative breast cancer (TNBC) cell lines and a hormone therapy resistant model of breast cancer in order to improve our understanding of the bioimpedance spectra of breast cancer subtypes. Third, we explored strategies to improve the sensitivity of the microelectrodes to bioimpedance measurements from breast cancer cells. We investigated nano-scale coatings on the surface of the electrode and geometrical variations in a branched electrode design to accomplish this. This work demonstrates the promise of bioimpedance technologies in monitoring diseased cells and their responses to pharmaceutical agents, and motivates further research in customization of this technique for use in personalized medicine. / Ph. D.
|
89 |
Voltage Controlled Current Source with Reduced Stray Capacitances Effect and Extended Impedance and Frequency RangesNouri, Hanen 31 July 2024 (has links)
Bioimpedance spectroscopy is a non-invasive measurement technique in medical applications. It requires low amplitude current excitation to maintain safety. Designing a current source for this purpose is a challenge as it needs to maintain a stable and safe excitation current, below 0.5 mA, independent of the impedance and frequency.
Various topologies of voltage controlled current sources exist in the literature, where the Enhanced Howland Current Source (EHCS) and the Dual HCS (DHCS) show advantages concerning low output current deviation and high output impedance.
They are composed of operational amplifiers and resistors, where the operational amplifier's non-ideal characteristics, resistors' tolerance influence the circuit performance. In this thesis, we propose an analytical model to systematically select circuit components.
Stray capacitances influence the circuit' performance. Thus, we propose a new structure of the Howland current source to eliminate their effects. We have thereby successfully grounded the measured impedance on a virtual ground and isolated it from stray capacitances. As a result, we achieve a wide working bandwidth of 5 MHz and 7 MHz for EHCS and DHCS, respectively. Moreover, the circuits can deliver precise current for a high range of load reaching 10 kOhm.
The developed circuit solves critical requirements in the development of a bioimpedance spectrometers by ensuring the safety and accuracy in a wide frequency range and a wide impedance range.:1 Introduction
2 Theoretical background
3 Howland current sources
4 Methodical design of Howland Current Sources
5 Experimental investigations
6 Conclusions and Outlook
|
90 |
Srovnání různých metod měření tělesného složení u žen rozdělených do skupin dle BMI / The comparison of different methods of body fat measuring by ensemble of adult women devided into five groups according to the BMI levelŠebková, Jana January 2011 (has links)
Title: The comparison of different methods of body fat measuring by ensemble of adult women devided into five groups according to the BMI level. Objectives: The aim of this thesis is to compare values of gained percentage of total body fat by descriptive method such as bioelectrical impedance analysis and skinfolds measuring in comparison with "gold standard method" DEXA and to evaluate the usability of each method of body composition measuring by five groups of women, devided according to BMI level (in range 20-47 kg/m2 ). The purpose of this thesis is to find the most useful method especially for the overweight and obese women (BMI over 30 kg/m2 ) and to estimate the equation for the whole group. The other part of this thesis is the theoretical conclusion of the matters of body composition assessing and the importance of good knowledge about this topic for physiotherapists. Methods: The study was realizing from January of 2010 to March of 2011. There were 136 women, who were clients of Fitness center of VŠTJ Medicina Praha and jointed to the group voluntarely. The criteria of choosing the subjects into the study were: age 18 - 75 years, BMI 20 ≤ 45 kg/m2 , relatively healthy without accute disease. Women with cardiostimulator, pregnant women or nursing mothers were excluded. The monitored...
|
Page generated in 0.0678 seconds