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1.
Journal of Biomedical Engineering ; (6): 12-17, 2011.
Artigo em Chinês | WPRIM | ID: wpr-260858

RESUMO

Based on multi-layer dielectric model of spherical biological cell, a simulating method of frequency characteristics of inner and outer membranes is presented in this paper. Frequency-domain analysis showed that inner and outer membranes subjected to pulsed electric field exhibit band-pass and low-pass filter characteristics, respectively. A calculating method of the transmembrane potential of inner and outer membranes induced by time-varying electric field was introduced, and the window effect between electric field and transmembrane potential was also analyzed. When the duration is reduced from microsecond to sub-microsecond, and to nanosecond, the target induced was from the outer membrane to inner membrane gradually. At the same time, the field intensity should be increased to induce corresponding bioelectric effects. Window effect provides theoretical guidance to choosing reasonable parameters for application of pulsatile electric field in tumor treatment.


Assuntos
Humanos , Membrana Celular , Fisiologia , Efeitos da Radiação , Simulação por Computador , Campos Eletromagnéticos , Potenciais da Membrana , Fisiologia , Efeitos da Radiação , Modelos Biológicos
2.
Journal of Biomedical Engineering ; (6): 446-450, 2011.
Artigo em Chinês | WPRIM | ID: wpr-306541

RESUMO

In order to investigate the effects of electric pulses on cancer cells, we carried out the experiments with exposing HepG2 and L02 to electric pulses (1 kV/cm, l00 micros, 1 Hz) for different lengths of time (8 s, 15 s, 30 s, 60 s). Annexin V-FITC Kit and Flow cytometry were used to study the apoptosis of treated cells. The results showed that the electric pulses of 1 kV/cm, l00 micros, 1 Hz for 8 s could not induce tumor cells apoptosis. Apoptosis was observed when tumor cells were stimulated for 15 s and longer, and the apoptosis percentage increased with the increase of stimulation time. Furthermore, tumor cells were more sensitive than normal cells in response to electrical pulses. Rhodamine 123 and Laser Scanning Confocal Microscope (LSCM) were used to make a real-time study of mitochondrial transmembrane potential (Deltapsim) when the tumor cells were exposed to electric pulses for 60 s. No significant change of Deltapsim was observed within 30 s stimulation. After that, the Deltapsim increased sharply and declined later, suggesting that the mitochondrial pathway may be one of the apoptosis mechanism induced by electric pulses.


Assuntos
Humanos , Apoptose , Efeitos da Radiação , Campos Eletromagnéticos , Células Hep G2 , Potencial da Membrana Mitocondrial , Fisiologia , Efeitos da Radiação , Fatores de Tempo
3.
Journal of Biomedical Engineering ; (6): 1128-1132, 2010.
Artigo em Chinês | WPRIM | ID: wpr-260925

RESUMO

In the light of optical theory, we advanc an ultra-wideband impulse radiating antenna (IRA) which is composed of an ellipsoidal reflector and a cone radiator. The high-intensity ultra-short electric pulses radiated by IRA can be transferred into the deep target in tissue non-invasively and be focused effectively. With the focused picosecond electric pulses, the organelles (mitochondria) transmembrane potential shall change to collapse under which the tumor cells will be targetly induced to apoptosis, so the method of non-invasive treatment of tumors would be achieved. Based on the time-domain electromagnetic field theory, the propagation characteristics of picosecond electric pulses were analyzed with and without the context of biological tissue, respectively. The results show that the impulse characteristics of input pulse were maintained and the picosecond electric pulses can keep high resolution in target areas. Meanwhile, because of the dispersive nature of medium, the pulse amplitude of the pulses will attenuate and the pulse width will be broadened.


Assuntos
Humanos , Apoptose , Efeitos da Radiação , Terapia por Estimulação Elétrica , Métodos , Eletrodos , Fenômenos Eletromagnéticos , Eletroporação , Métodos , Neoplasias , Patologia , Terapêutica
4.
Journal of Biomedical Engineering ; (6): 268-272, 2009.
Artigo em Chinês | WPRIM | ID: wpr-280218

RESUMO

The aim of our study was to determine the effects of energy controllable steep pulse (ECSP) on the cytoskeleton of human ovarian cancer cells SKOV3. SKOV3 cells were divided into five groups under ECSP treatment with different parameters (frequency, pulse duration, peak value of voltage). The positive control group included SKOV3 cells treated with volchicine; the negative control group included SKOV3 cells subjected to sham-lightning stroke. Rhodamine-phalloidine was used to label microfilament directly. After using immunofluorescence to label microbules, we observed them by means of Confocal Laser Scanning Microscope. Making specimen and using electronmicroscope, we observed the ultramicrostructure of cystoskeleton. The results showed that ECSP-treated-SKOV3 cells lost their normal cystoskeleton network structure. There were obvious microfilament disaggregation, diffused skeleton protein, and disappearance of cystoskeleton network structure. Also noticeable were microbule disaggregation, reduction of pseudopod, obvious microfilament disaggregation, permutation disorder and structure disappearance. Moreover, this effect bears a direct relation with dosage.


Assuntos
Feminino , Humanos , Linhagem Celular Tumoral , Citoesqueleto , Condutividade Elétrica , Campos Eletromagnéticos , Eletroporação , Neoplasias Ovarianas , Patologia , Pulso Arterial
5.
Journal of Biomedical Engineering ; (6): 1060-1063, 2009.
Artigo em Chinês | WPRIM | ID: wpr-244691

RESUMO

This was a study aimed to observe the proliferating ability inhibited by energy controllable steep pulse (ECSP) and to detect the expression of gene with relation to the proliferating ability of the tumor in breast cancer cell line; the possible mechanisms were also addressed. Human breast cancer cell line MDA-MB-231 was treated with ECSP; the apoptosis and the expression of tumor suppressor gene--Rb genes and E2F1 genes in ECSP group and control group were detected by TUNEL staining and Reverse Transcripitional PCR respectively. ECSP was found to inhibit the proliferating ability of breast cancer cells markedly, the cell amount in ECSP group decreased and the TUNEL positive cells increased obviously, compared to control; 24 hours after treatment the expression of Rb genes mRNA increased, whereas the expression of E2F1 mRNA decreased. These findings indicate that the proliferating ability of breast cancer cells can be inhibited by ECSP markedly, the apoptosis of breast cancer cell can be induced by ECSP, and the Rb genes and E2F1 genes may be involved in the course.


Assuntos
Feminino , Humanos , Apoptose , Efeitos da Radiação , Neoplasias da Mama , Patologia , Linhagem Celular Tumoral , Proliferação de Células , Efeitos da Radiação , Terapia por Estimulação Elétrica , Métodos , Campos Eletromagnéticos , Eletroporação , Métodos
6.
Journal of Biomedical Engineering ; (6): 637-641, 2008.
Artigo em Chinês | WPRIM | ID: wpr-342774

RESUMO

This experiment was designed to study the apoptosis and related mechanism of adherent liver tumor cells (SMMC-7721) and adherent normal liver cells (HL-7702) when they were exposed to the steep pulse generated by the steep pulse apparatus for tumor treatment. The results showed that the steep pulse of 200 V could induce tumor cells apoptosis. The tumor cells presented with their apoptosis when they were exposed to the steep pulse from 200 V to 250 V. Laser scanning confocal microscopy was used to make a real time study of calcium burst when the adherent tumor cells were exposed to the steep pulse. The results showed:On the condition of no extracellular Ca2+, the concentration of Ca2+ in tumor cells exposed to the steep pulse of 150 V did not change; the concentration of Ca2+ in tumor cells exposed to the steep pulse of 200 V decreased; the concentration of Ca2+ in tumor cells exposed to the steep pulse of 250 V decreased more evidently. On the condition of existing extracellular Ca2+, the concentration of Ca2+ in tumor cells exposed to the steep pulse of 150 V did not change; the concentration of Ca2+ in tumor cells exposed to the steep pulse of 200 V decreased little; the concentration of Ca2+ in tumor cells exposed to the steep pulse of 250 V reduced little, too. Maybe the change of calcium burst in the tumor cells is the mechanism of apoptosis when cells are exposed to the steep pulse.


Assuntos
Humanos , Apoptose , Efeitos da Radiação , Cálcio , Metabolismo , Eletricidade , Campos Eletromagnéticos , Hepatócitos , Biologia Celular , Patologia , Neoplasias Hepáticas , Metabolismo , Patologia , Microscopia Confocal , Células Tumorais Cultivadas
7.
Journal of Biomedical Engineering ; (6): 1206-1209, 2008.
Artigo em Chinês | WPRIM | ID: wpr-318183

RESUMO

In recent years, many experts have done some researches on experiment and mechanism of intracellular electromanipulation (IEM) under nanosecond pulsed electric field (nsPEF). The experiment results have shown that nsPEF could not induce electroporation of cell membrane, but could induce intracellular effects such as apoptosis, calcium release, enhancement of gene expression, and fragmentation of DNA and chromosome. In order to account for the phenomenon, researchers believe that when the pulse width of the pulsed electric field is larger than the charging time of plasma membrane, the pulsed electric field mainly targets on the outer membrane of cell; and that the effect of the pulsed electric field on nucleus and nuclear membrane increases with the decrease of the pulse width. It is also believed that the effect of electroporation changes from the outer membrane to intracellular electromanipulation when the pulse width decreases to a value being smaller than the charging time of plasma membrane.


Assuntos
Apoptose , Cálcio , Metabolismo , Membrana Celular , Metabolismo , Núcleo Celular , Metabolismo , Fenômenos Fisiológicos Celulares , Campos Eletromagnéticos , Eletroporação , Expressão Gênica
8.
Journal of Biomedical Engineering ; (6): 492-495, 2007.
Artigo em Chinês | WPRIM | ID: wpr-357667

RESUMO

This experimental study was designed to investigate the effects and the expressions of microvessel density (MVD), vascular endothelial growth factor (VEGF) on the transplanted tumor in the rat model with Walker-256 after energy controllable steep pulse(ECSP). The experiment revealed that the steep pulse electrical field has better effect on tumor, compared with the control. The positive cell staining intensity of VEGF in the control group was significantly higher than that in ECSP group (P < 0.05). The number of MVD in the tumor tissues of ECSP group was significantly lower than that of tumor control group (P < 0.05). These results showed that ECSP could inhibit the growth and angiogenesis of tumor and its pathway is to down-regulate the expression of VEGF possibly.


Assuntos
Animais , Feminino , Masculino , Ratos , Carcinoma 256 de Walker , Terapêutica , Condutividade Elétrica , Terapia por Estimulação Elétrica , Métodos , Campos Eletromagnéticos , Eletroporação , Métodos , Neovascularização Patológica , Ratos Wistar , Fator A de Crescimento do Endotélio Vascular , Metabolismo
9.
Journal of Biomedical Engineering ; (6): 230-234, 2007.
Artigo em Chinês | WPRIM | ID: wpr-357727

RESUMO

Pulsed electric fields can induce various kinds of biological effects that are essentially different from the normal electric fields, especially the interactions of Nanosecond Pulsed electric field (nsPEF) with cells. The biological effects of different pulsed electric fields on cell membranes, cytoplasmic matrixes, cell growth are introduced in this paper. Based on these effects, some applications of pulsed electric fields in cancer therapy, gene therapy, and delivery of drugs are reviewed in details.


Assuntos
Membrana Celular , Metabolismo , Efeitos da Radiação , Fenômenos Fisiológicos Celulares , Campos Eletromagnéticos , Eletrofisiologia , Eletroporação , Terapia Genética , Métodos , Neoplasias , Terapêutica
10.
Journal of Biomedical Engineering ; (6): 253-256, 2007.
Artigo em Chinês | WPRIM | ID: wpr-357722

RESUMO

This study sought to evaluate the effect of steep pulsed electric fields (SPEFs) on the immune response of Wistar mice inoculated with Walker256 sarcoma. Thirty mice were randomly divided into three groups: control group (group A, inoculated with Walker256 sarcoma, not treated), treatment group (group B, inoculated with Walker256 sarcoma, treated by SPEFs), and normal control group (group C, inoculated with normal saline, not treated). Tumor size was measured before and every 3 days after treatment by vernier caliper. MTT methods were used to assess the lymphocytes proliferation and the natural killer (NK) cells activity. TNF-a activity was measured by ELISA. Statistical analysis was performed utilizing the SPSS10.0 software package. The experiment results revealed that tumor growth was significantly inhibited in group B as compared with group A (P < 0.01), and that lymphocytes proliferation, NK cells activity and TNF-a activity in group B were not significantly different from those in group C (P = 0.953, P = 0.130, P = 0.080, respectively) but markedly higher than those in group A (P < 0.05). The results also showed that SPEFs could not only kill tumor cells but also induce antitumor immune response and improve the immune function of the host efficiently.


Assuntos
Animais , Feminino , Masculino , Camundongos , Carcinoma 256 de Walker , Alergia e Imunologia , Patologia , Terapêutica , Campos Eletromagnéticos , Células Matadoras Naturais , Alergia e Imunologia , Leucócitos , Alergia e Imunologia , Ativação Linfocitária , Transplante de Neoplasias , Pulso Arterial , Distribuição Aleatória , Baço , Biologia Celular , Fator de Necrose Tumoral alfa
11.
Journal of Biomedical Engineering ; (6): 313-317, 2006.
Artigo em Chinês | WPRIM | ID: wpr-249611

RESUMO

The mechanical properties of tumor cells adhering to extracellular matrix (ECM) are closely related with their invasion and metastesis. In this study we investigated the adhesive mechanical properties between hepatocellular carcinoma cells(HCC) and the collagen I coated surfaces from the viewpoint of cell cycle by coupling cellular biology and cellular mechanics, using micropipette aspiration and cell synchronization technique. The results showed that the synchronous G1 and S phase HCC cells were achieved by use of thymine-2-desoryriboside, colchicines sequential blockage method and double thymine-2-desoryriboside blockage method, and that the synchronous rates of G1 and S phase HCC amounted to 74.09% and 90.39% respectively. Within the ranges of dosing and timing in this study, the adhesion of HCC cells to collagen I displayed dose dependent and time dependent patterns. S phase cells had small force of adhesion to collagen I as compared with G1 phase and controlled cells(P<0.001), which suggested that G1 phase HCC may play an important role in the step of invading interstitial connective tissue in the metastasis pathway of HCC through blood circulation. These are of significance to unveiling the mechanism of HCC metastasis.


Assuntos
Animais , Ratos , Adesão Celular , Ciclo Celular , Colágeno Tipo I , Metabolismo , Neoplasias Hepáticas Experimentais , Metabolismo , Patologia , Metástase Neoplásica , Células Tumorais Cultivadas
12.
Journal of Biomedical Engineering ; (6): 497-500, 2005.
Artigo em Chinês | WPRIM | ID: wpr-354265

RESUMO

Pulsed electric fields (PEFs) with fixed frequency, width and gradually increased peak value of voltage was applied to 30 healthy rabbit liver tissues. The specific aims were to explore the feasibility of establishing a model of in vivo PEFs distribution in healthy rabbit liver tissues and to provide important references for clinical electrochemotherapy and for electrotransfer. Repeated experiment and self-comparison statistics design were implemented. The rabbit underwent the experiment under intravenous anesthesia and their liver tissues, after exposure to PEFs, were sent for HE staining. Necrotic borderline was visible 3 days after PEFs application, the necrotic shape of concentric circle was evident around the electrodes under optical microscope at lower voltage, as voltage increasing, two necroses in the shape of concentric circle gradually enlarged; nuclei with chromatin condensation, fragmentation and lysis alterations were seen in the middle region between the needles; concentric circles changed into ellipse fusiform and finally overlaped each other forming irregular necrosis contours. Cell cavitation and tissues ischemia were also observed within electric field. The shape of tissue necrosis from the experiment was noted to correlate with theoretic simulation of electric field distribution. Therefore, rabbit liver tissues can be a good carrier for in vivo modeling of electric field distribution when the lethal effects of PEFs in tissues are investigated. PEFs also show safety for the surrounding normal tissue while causing damage or injury to the target area therapeutically.


Assuntos
Animais , Masculino , Coelhos , Eletricidade , Eletroquimioterapia , Fígado , Patologia , Modelos Teóricos , Necrose
13.
Journal of Biomedical Engineering ; (6): 896-900, 2005.
Artigo em Chinês | WPRIM | ID: wpr-238316

RESUMO

This study was conducted to observe the lethal effects of steep pulsed electric field(SPEF) on the cancerous squamous cells in BALB/c mice. Female mice were inoculated with the solution of cervical cancer cells line. The tumor-bearing mice of the experiment group were exposed to SPEF. Then, the histomorphological changes were examined and compared between experiment group and control group. The histological and antitumor assay showed that SPEF could selectively injure tumor cells and inhibit cell proliferation. After treatment, pyknosis, karyoclasis and karyolysis of cancer cells were observed under light and electron mircroscope. More serious changes appeared some days later. These results indicate that SPEF have lethal effects on cervical cancer. It may prolong the survival period of tumor-bearing mice.


Assuntos
Animais , Feminino , Camundongos , Linhagem Celular Tumoral , Proliferação de Células , Campos Eletromagnéticos , Eletroporação , Métodos , Camundongos Endogâmicos BALB C , Transplante de Neoplasias , Neoplasias do Colo do Útero , Patologia
14.
Journal of Biomedical Engineering ; (6): 546-548, 2004.
Artigo em Chinês | WPRIM | ID: wpr-342668

RESUMO

To assess study the cytocidal and inhibitory effects of steep pulsed electric fields (SPEFs) on ovarian cancer cell line SKOV3, the cancer cell suspension was treated by SPEFs with different parameters (frequency, pulse duration, peak value of voltage). Viability rate and growth curves of two test groups (high dosage and low dosage of SPEFs) and one control group were also measured. The DNA contents and cell cycle were analyzed by flow cytometry (FCM). Different dosing levels of SPEFs exerted obviously different effects on cancer cell viability. With the enhancement of each pulse parameter, the viability rate was promoted and the inhibitory effect on the proliferation of treated cells was more evident. The cells exposed to SPEFs grew slower than the control. The ratio of S+G2/M phase cells was decreased, which restrained the DNA synthesis and division, but the ratio of G0/G1 phase cells was increased in the treated groups. It was also indicated that the SPEFs blocked the cell transition from G0/G1 phase to S+G2/M phase. There was a significant difference in cell cycle between treated group and control group (P<0.01). Lethal effects of SPEFs were represented by inhibiting the cancer cell proliferation at the cell level and by influencing the cell cycle at the DNA level.


Assuntos
Feminino , Humanos , Adenocarcinoma , Patologia , Ciclo Celular , Efeitos da Radiação , Linhagem Celular Tumoral , Proliferação de Células , Efeitos da Radiação , DNA , Campos Eletromagnéticos , Eletroporação , Citometria de Fluxo , Neoplasias Ovarianas , Patologia , Pulso Arterial
15.
Journal of Biomedical Engineering ; (6): 433-435, 2004.
Artigo em Chinês | WPRIM | ID: wpr-291095

RESUMO

To investigate the lethal effect of steep pulsed electric fields (SPEFs) on cancer cells and the life-prolonging effect of SPEFs on the survival of tumour-bearing mice, this study was carried out with the use of SPEFs to treat 40 BALB/C mice inoculated by cervical cancer. The lethal effect on cancer cells and the life-prolonging effect on tumour-bearing mice were examined and compared between the experiment group and control group. The survival periods of the experiment group and control group were 52.05 days and 33.03 days, respectively. There was a significant difference in survival curve between the two groups. The results confirmed the inhibitiory effect and lethal effect of SPEFs on cancer cells. SPEFs can prolong the survival period of tumour-bearing mice.


Assuntos
Animais , Feminino , Camundongos , Eletrodos , Campos Eletromagnéticos , Eletroporação , Camundongos Endogâmicos BALB C , Transplante de Neoplasias , Pulso Arterial , Taxa de Sobrevida , Neoplasias do Colo do Útero , Patologia , Terapêutica
16.
Journal of Biomedical Engineering ; (6): 337-339, 2002.
Artigo em Chinês | WPRIM | ID: wpr-263595

RESUMO

In these years, the electrical technology is widely applied in the study of biomedical engineering. Using electroporation therapy (EPT) to treat tumor is associated with biomedical engineering, electrical new technology, computer technology and microelectronic technology, which is a new marginal subject. Many experts have studied the mechanism and clinical treatment of the cell membrane electroporation phenomenon under electrical fields. These researches have shown that the membrane electroporation can stimulate the transport and intake of various drugs, which improves the tumoricidal effect of these drugs. The researchers have also been exploring the phenomenon that irreversible electrical breakdown (IREB) of cell membrane under high electrical fields and steep pulses leads to the death of tumor.


Assuntos
Humanos , Membrana Celular , Eletroquimioterapia , Neoplasias , Tratamento Farmacológico , Pesquisa
17.
Journal of Biomedical Engineering ; (6): 440-443, 2002.
Artigo em Chinês | WPRIM | ID: wpr-357007

RESUMO

Experimental research of injury on tumor tissue in vitro is conducted with homemade energy-controllable steep pulse device. With the comparison of histological assay results between treatment group and non-treatment group, basic phenomenon of electrochemical reaction and pathology reaction of tumor tissue during the experiment is observed. The results showed the irreversible breakdown penetrating effect of energy-controllable steep pulse on tumor cells and the feasibility of this therapy are also demonstrated. These results provide a consolidate theoretic and applicable basis for further study on mechanism and animal experiment in vivo.


Assuntos
Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Terapia por Estimulação Elétrica , Métodos , Campos Eletromagnéticos , Técnicas In Vitro , Neoplasias , Patologia , Terapêutica
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