RESUMEN
Electrochemotherapy is a cancer treatment in which local pulsed electric fields are delivered through electrodes. The effectiveness of the treatment depends on exposing the tumor to a threshold electric field. Electrode geometry plays an important role in the resulting electric field distribution, especially in hard-to-reach areas and deep-seated tumors. We designed and developed a novel tetrapolar single-needle electrode for proper treatment in bone cavities. In silico and in vitro experiments were performed to evaluate the electric field and electric current produced by the electrode. In addition, tomography images of a real case of nasal cavity tumor were segmented into a 3D simulation to evaluate the electrode performance in a bone cavity. The proposed electrode was validated and its operating range was set up to 650 V. In the nasal cavity tumor, we found that the electrode can produce a circular electric field of 3 mm with an electric current of 14.1 A at 500 V, which is compatible with electrochemotherapy standards and commercial equipment.
Asunto(s)
Electroquimioterapia , Neoplasias , Humanos , Simulación por Computador , Agujas , ElectrodosRESUMEN
Biological tissue exhibits a strong dielectric dispersion from DC to GHz. Implementing biological dispersion in the time domain with commercial finite element method software could help improve engineering analysis of electrical transient phenomena. This article describes the steps required to implement time-domain biological dispersion with commercial finite element method software. The study begins with the presentation of a genetic algorithm to fit the experimental dispersion curve of Solanum tuberosum (potato tuber) to multipoles of first-order Debye dispersion. The results show that it is possible to represent the biological dispersion of S. tuberosum from 40 Hz to 10 MHz in a 4-pole Debye dispersion. Then, a set of auxiliary differential equations is used to transform the multipole Debye dispersion from the frequency domain to the time domain. The equations are implemented in the commercial software COMSOL Multiphysics. A comparison between the frequency and time domain simulations was used to validate the method. An analysis of the electric current with square-wave pulsed voltage was performed. We found that the computer implementation proposed in this work can describe the biological dispersion and predict the electric current.
Asunto(s)
Modelos Biológicos , Programas Informáticos , Análisis de Elementos Finitos , ElectricidadRESUMEN
Electrochemotherapy (ECT) and Irreversible electroporation (IRE) are cancer treatments based on electric field distribution in tissues. Solanum tuberosum (potato tissue) phantom is known to mimic changes in the electrical conductivity that occur in animal tissues during electroporation (EP). Electric field distribution is assessed through enzymatic staining. However, the 24-h wait for this assessment could slow agile response scenarios. We developed and validated the Musa acuminata (cavendish banana) conductivity model, which quickly evaluates EP by tissue staining. We investigated the frequency response of the tissue using impedance spectroscopy analysis, conductivity changes, and enzymatic staining. We optimized three usual EP models: adapted Gompertz, smoothed Heaviside, and the sigmoid or logistic function. We found dielectric parameters in banana tissue similar to those in potato (electrical conductivity of 0.035 S/m and relative permittivity of 4.1×104). The coefficients of determination R2 were 99.94% (Gompertz), 99.85% (Heaviside), and 99.58% (sigmoid). The sigmoid and Heaviside functions described the calibration and validation electric currents with 95% confidence. We observed the electroporated areas in bananas 3h30m after EP. Staining was significant after 450 V/cm. The conductivity model of Musa acuminata suits treatment planning, hardware development, and training scenarios. Banana phantom supports the 3Rs practice and is a reliable alternative for potato in EP studies.
Asunto(s)
Electroquimioterapia , Musa , Animales , Terapia de Electroporación , Electroporación , Conductividad EléctricaRESUMEN
Electroporation alters cell membrane structure and tissue electrical properties by short and intense pulsed electric fields (PEF). Static mathematical models are often used to explain the change in electrical properties of tissues caused by electroporation. Electric pulse repetition rate may play an important role, as tissue dielectric dispersion, electroporation dynamics, and Joule heating may affect the electrical properties. In this work, we investigate the effects on the magnitude of the electric current when the repetition rate of the standard electrochemotherapy protocol is increased. Liver, oral mucosa, and muscle tissues were studied. Ex vivo animal experiments show that the magnitude of the electric current increases when the repetition rate is changed from 1 Hz to 5 kHz (10.8% for liver, 5.8% for oral mucosa, and 4.7% for muscle). Although a correction factor could reduce the error to less than 1%, dynamic models seem to be necessary to analyze different protocol signatures. Authors should be aware that static models and experimental results can only be compared if they use exactly the same PEF signature. The repetition rate is a key information to consider in the pretreatment computer study because the current at 1 Hz PEF differs from a 5 kHz PEF.
Asunto(s)
Electroquimioterapia , Animales , Electroquimioterapia/métodos , Electroporación/métodos , Electricidad , Modelos Teóricos , HígadoRESUMEN
Most patients with diabetes mellitus are asymptomatic, which leads to delayed and more complex treatment. At the same time, most individuals are routinely subjected to standard clinical laboratory examinations, which create large health datasets over a lifetime. Computer processing has been used to search for health anomalies and predict diseases using clinical examinations. This work studied machine learning models to support the screening of diabetes through routine laboratory tests using data from laboratory tests of 62,496 patients. The classification and regression models used were the K-nearest neighbor, support vector machines, Bayes naïve, random forest models, and artificial neural networks. Glycated hemoglobin, a test used for diabetes diagnosis, was used as the target. Regression models calculated glycated hemoglobin directly and were later classified. The performance of classification computer models has been studied under various subdataset partitions and combinations (e.g., healthy, prediabetic, and diabetes, as well as no healthy and no diabetes). The best single performance was achieved with the artificial neural network model when detecting prediabetes or diabetes. The artificial neural network classification model scored 78.1%, 78.7%, and 78.4% for sensitivity, precision, and F1 scores, respectively, when identifying no healthy group. Other models also had good results, depending on what is desired. Machine learning-based models can predict glycated hemoglobin values from routine laboratory tests and can be used as a screening tool to refer a patient for further testing.
Asunto(s)
Diabetes Mellitus , Estado Prediabético , Teorema de Bayes , Diabetes Mellitus/diagnóstico , Hemoglobina Glucada , Humanos , Aprendizaje Automático , Redes Neurales de la Computación , Estado Prediabético/diagnóstico , Máquina de Vectores de SoporteRESUMEN
A specific pulsed electric field protocol can be used to induce electroporation. This is used in the food industry for yeast pasteurization, in laboratories for generic transfer and the medical field for cancer treatment. The sensing of electroporation can be done with simple 'instantaneous' voltage-current analysis. However, there are some intrinsic low-frequency phenomena superposing the electroporation current, such as electrode polarization. The biological media are non-homogeneous, giving them specific characterization in the broad frequency spectrum. For example, the cell barrier, i.e., cell membrane, causes so called ß-dispersion in the frequency range of tens to thousands of kHz. Electroporation is a dynamic phenomenon characterized by altering the cell membrane permeability. In this work, we show that the impedance measurement at certain frequencies could be used to detect the occurrence of electroporation, i.e., dielectric dispersion modulated sensing. This approach may be used for the design and implementation of electroporation systems. Yeast suspension electroporation is simulated to show changes in the frequency spectrum. Moreover, the alteration depends on characteristics of the system. Three types of external buffers and their characteristics are evaluated.
Asunto(s)
Electroporación , Saccharomyces cerevisiae , Membrana Celular/metabolismo , Impedancia Eléctrica , Electroporación/métodos , SuspensionesRESUMEN
Electrochemotherapy is a selective electrical-based cancer treatment. A thriving treatment depends on the local electric field generated by pairs of electrodes. Electrode damage as deflection can directly affect this treatment pillar, the distribution of the electric field. Mechanical deformations such as tip misshaping and needle deflection are reported with needle electrode reusing in veterinary electrochemotherapy. We performed in vitro and in silico experiments to evaluate potential problems with ESOPE type II electrode deflection and potential treatment pitfalls. We also investigated the extent to which the electric currents of the electroporation model can describe deflection failure by comparing in vitro with the in silico model of potato tuber (Solanum tuberosum). The in silico model was also performed with the tumor electroporation model, which is more conductive than the vegetal model. We do not recommend using deflected electrodes. We have found that a deflection of ± 2 mm is unsafe for treatment. Inward deflection can cause dangerous electrical current levels when treating a tumor and cannot be described with the in silico vegetal model. Outward deflection can cause blind spots in the electric field.
Asunto(s)
Simulación por Computador , Conductividad Eléctrica , Electroquimioterapia , Modelos Teóricos , Neoplasias/tratamiento farmacológico , Humanos , AgujasRESUMEN
Electrochemotherapy (ECT) requires covering the entire tumor and safe margins with a suitable pulsed electric field (PEF). The PEF distribution depends on the biological and electrical parameters. The biological tissue may have diffractive geometry with non-linear conductivity behavior due to electroporation. That characteristic may provoke ECT-insufficient electric field regions, also known as blind spots. The conductive gels can fill holes and bumps, being a tool to homogenize the electric field. We executed an in vitro vegetal tissue experiment to validate a numerical model under different gels conditions. We used a study case in silico experiment to investigate gel influence on PEF distribution and electrical current. We propose a case-oriented methodology to optimize the gel during the ECT pre-treatment. Results show that the optimized gel completely treats a region of interest while avoiding unnecessary current increase and damage to healthy tissue by over treatment. The optimized gel conductivity may be lower than the previously reported (0.5 to 1 S/m) and may be in the range of the commercially available gels. For a veterinary mastocytoma exophytic nodule ECT case study, using needles electrode, the 0.2 S/m gel is the optimum gel.
Asunto(s)
Electroquimioterapia , Simulación por Computador , Computadores , Conductividad Eléctrica , Electroporación/métodos , GelesRESUMEN
Introdução: A hiperatividade da musculatura glabelar e as consequentes rugas são queixas frequentes na cirurgia plástica. O tratamento consiste em impedimento dos músculos relacionados. Propomos uma abordagem fechada para o tratamento da musculatura glabelar. Métodos: 78 pacientes foram operados entre abril de 2012 e agosto de 2015. A miotomia é realizada guiada pela marcação e tem início utilizando fio de poliglactina 0 ou fio de aço, passando várias vezes através das linhas marcadas, entrando pelo supercílio e utilizando o plano justaperiostal, retornando através do mesmo orifício da agulha em direção ao orifício de entrada, agora usando o plano subcutâneo. Resultados: Foram obtidos bons resultados em todos os casos com impedimento da atividade da musculatura glabelar durante o período avaliado (pelo menos 1 ano), com melhora das rugas e hiperatividade. As complicações observadas foram parestesia temporária na região frontal central (35 casos) e recidiva parcial (4 casos). Não foi observado nenhum caso de recorrência completa. As opções de tratamento cirúrgico de longo prazo para rugas glabelar são miotomia, neurotomia parcial ou miectomia. A miotomia glabelar fechada evita algumas possíveis complicações associadas a essas opções, diminui o tempo cirúrgico utilizando instrumentos cirúrgicos convencionais, permite a correção de assimetria, com menos edema, menos equimoses e evita cicatrizes. Conclusão: A miotomia glabelar fechada parece ser uma boa alternativa às outras opções cirúrgicas tradicionais, porque evita cicatrizes, permite correção de assimetria e apresenta bons resultados a longo prazo.
Introduction: Hyperactivity of the glabellar musculature and resulting wrinkles are frequent complaints in the field of plastic surgery. Treatment consists of blocking the involved muscles. We propose a closed approach for the treatment of glabellar musculature. Methods: Seventy-eight patients underwent operation between April 2012 and August 2015. Myotomy includes the use of markings and polyglactin 0 wire or steel wire, passing through the marked lines several times, entering the eyebrow and using the juxtaperiostal plane, returning through the same orifice of the needle toward the entry hole, and using the subcutaneous plane. Results: Good results were obtained in all cases by preventing glabellar muscle activity during the period evaluated (at least 1 year), with improvement in wrinkles and muscle hyperactivity. The complications observed included temporary paresthesia in the frontal region (35 cases) and partial recurrence (4 cases). There was no case of total recurrence. The options for long-term surgical treatment of glabellar wrinkles are myotomy, partial neurotomy, or myectomy. Closed glabellar myotomy prevents some possible complications associated with these options, reduces the surgical time, requires the use of conventional surgical instruments, eliminates scarring, and causes asymmetric correction, less edema, and fewer bruises. Conclusion: Closed glabellar myotomy seems to be a good alternative compared to other traditional surgical options, because it eliminates scarring, allows correction of asymmetry, and presents good long-term results.
Asunto(s)
Humanos , Adulto , Persona de Mediana Edad , Historia del Siglo XXI , Pacientes , Ritidoplastia , Procedimientos de Cirugía Plástica , Difusión de Innovaciones , Estética , Músculos Faciales , Miotomía , Pacientes/psicología , Ritidoplastia/instrumentación , Ritidoplastia/métodos , Procedimientos de Cirugía Plástica/instrumentación , Procedimientos de Cirugía Plástica/métodos , Músculos Faciales/cirugía , Miotomía/instrumentación , Miotomía/métodosRESUMEN
A lipoaspiração permanece como um dos procedimentos mais realizados pelos cirurgiões plásticos (1-3). O aumento da segurança no ambiente cirúrgico, o refinamento da técnica e a satisfação das pacientes contribuem para a popularidade desta intervenção idealizada por Ilouz, em 1979 (4). Tem-se observado, ainda, tanto no ambiente médico quanto na mídia, uma crescente preocupação não apenas com a nova forma dos pacientes, mas também com a segurança. O tecido adiposo atua como um verdadeiro órgão endócrino e é o principal depósito de triglicerídeos, que têm uma relação clássica com doença aterosclerótica e resistência insulínica (6, 7). Estudos recentes ligaram ainda o metabolismo lipídico dos adipócitos à manutenção de um estado inflamatório sistêmico de baixo grau, através de vários mediadores (8-10). Há evidências científicas (11) que mostram o aumento do percentual de obesos em nosso país e uma importante taxa de pessoas, com sobrepeso. Este estudo também relaciona a prevalência de diabetes e de hipertensão. A clássica inter-relação entre a quantidade de gordura corporal e as chamadas doenças metabólicas tem suscitado a investigação dos elementos envolvidos neste processo e de tratamentos para o controle dos mesmos. A descoberta da leptina na década de 1990 (12) chamou a atenção para a propriedade reguladora do tecido adiposo. Estudos posteriores (5, 13) relacionaram ainda a síntese de outros fatores. Decidimos fazer uma revisão da literatura para esclarecer o estágio atual das pesquisas, tentando ordená-las de forma didática para melhor compreensão e auxílio para uma conduta mais segura e eficiente nos pacientes submetidos à lipoaspiração.
Liposuction is one of the most frequently performed procedures by plastic surgeons. The increased safety associated with the surgical settings, technical refinements, and level of patient satisfaction have contributed to the popularity gained by this intervention since it was first introduced by Ilouz in 1979 (4). Moreover, among medical communities and the media, concerns have risen regarding not only the drastic changes in patients' appearance but also the safety of the procedure. Fat tissue is known to act as a legitimate endocrine organ (5), being the primary depository for triglycerides, which classically relate to atherosclerosis and insulin resistance (6, 7). Recent work has linked lipid metabolism in adipocytes to the maintenance of low levels of systemic inflammation through a series of mediators (8-10). Scientific evidence (11) revealed an increase in the percentage of obese people in our country, as well as a considerable proportion of overweight people. This study also investigates the relationship between the prevalence of diabetes and hypertension. The classic association between body mass index and common metabolic diseases has led to investigations focused on several factors involved in this relationship, along with research work directed at the treatments available. The discovery of leptin in the 1990s (12) highlights the regulatory properties of the adipose tissue, whereas recent studies (5, 13) have established a link with the synthesis of other factors. In this study, we aimed to perform a review of literatures that discuss the current state-of-the-art of scientific research, in which we organized published works in a didactic manner in order to facilitate better understanding, and promote the safety and efficacy of liposuction.
Asunto(s)
Humanos , Historia del Siglo XXI , Cirugía Plástica , Triglicéridos , Lipectomía , Tejido Adiposo , Colesterol , Factores de Riesgo , Interleucinas , Factor de Necrosis Tumoral alfa , Revisión , Leptina , Estudio de Evaluación , Diabetes Mellitus , Hipertensión , Cirugía Plástica/métodos , Triglicéridos/análisis , Triglicéridos/metabolismo , Lipectomía/métodos , Lipectomía/estadística & datos numéricos , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Colesterol/metabolismo , Interleucinas/análisis , Interleucinas/metabolismo , Factor de Necrosis Tumoral alfa/análisis , Factor de Necrosis Tumoral alfa/metabolismo , Leptina/metabolismo , Diabetes Mellitus/prevención & control , Hipertensión/prevención & controlRESUMEN
O neurofibroma plexiforme é uma das principais apresentações da neurofibromatose, com incidência maior no segmento cefálico e menos frequente no tronco. A sua ressecção torna-se um desafio em decorrência da rica vascularização e da infiltração aos planos profundos. Descrevemos o caso de um neurofibroma gigante acometendo todo o dorso de uma paciente jovem, com crescimento progressivo, associado a manchas café com leite e déficit cognitivo. A investigação clínico-radiológica mostrou se tratar de neurofibromatose tipo I e a abordagem cirúrgica foi realizada em dois tempos, por meio de enxertia de pele parcial em toda a área ressecada.
Plexiform neurofibroma is one of the major presentations of neurofibromatosis, with a higher incidence in cephalic segment and less common in the trunk. It's resection becomes a challenge due to its rich vascularization and infiltration to deep plans. We present the case of a giant neurofibroma embodying the whole back of a young patient, with progressive growth associated with café-au-lait spots and cognitive deficit. Clinical and radiologic inquiry indicated type 1 neurofibromatosis. Surgical resection was achieved in two steps, covering the naked area with split-thickness skin grafts.