基于射频能量的温控条件下离体猪肝组织的电阻抗特性研究

为探讨射频消融下温度特性与阻抗特性间的关联性,提高治疗效果。本研究对离体猪肝组织进行了射频消融实验,分析热作用下猪肝组织凝固性坏死的温度特性与阻抗特性。实验中控制猪肝组织的最高温度不超过60℃。研究发现,当组织温度低于50℃时,阻抗随温度升高而快速下降至平稳。当温度继续上升至60℃时,阻抗迅速增大。当温度保持在50～60℃,阻抗出现周期性先增大后减小的变化。结果证明,对于离体猪肝组织,其温度与阻抗存在一定的关联性。本研究可为后续利用阻抗变化率控制温度提供实验依据,为设计阻抗控制模式提供思路。     

小鼠背部皮肤的在体阻抗谱实验研究

皮肤中角质层与其他层面阻抗的巨大差异,使得将皮肤作为一个整体的阻抗特性研究较难开展。研究在体条件下无创或微创地检测与分析包含角质层的小鼠背部皮肤的阻抗特性。使用Agilent 4294A阻抗分析仪,测量麻醉状态下的15只C57BL/6小鼠背部皮肤的电阻抗频谱,使用表面电极和银针电极,分别对应皮肤和活性皮肤层阻抗数据。在整个实验频率范围(40～10⁷ Hz)内,随频率升高,皮肤阻抗幅值呈现-20dB/dec下降;活性皮肤层在40~10³ Hz之间幅值呈现-10 dB/dec下降,而在10³~10⁷ Hz之间呈现-3dB/dec下降。皮肤相位随频率上升呈现V型曲线,而活性皮肤层相位呈现Π型曲线。低频时,皮肤阻抗完全由角质层阻抗组成,活性皮肤层的贡献可以忽略不计;当频率为10⁵ Hz时,活性皮肤层阻抗占皮肤的10%多,而在10⁷ Hz以上时,活性皮肤层阻抗占整个皮肤的80%以上。皮肤阻抗与活性皮肤层阻抗在10³ Hz以下具有显著性差异(P<0.05),在10⁴ Hz以上无显著性差异。结果表明,表面电极与银针电极相结合的对比分析方法能够在微创前提下有效分析角质层在皮肤阻抗中的作用。     

离体胫骨的有限元分析

应力骨折是士兵、运动员中很常见的骨损伤，被认为是疲劳骨折。首先测量了士兵在齐步、正步、跑步三种步态下承受的地面载荷，然后用有限元方法分析了在这几种步态下胫骨中的应力分布。结果表明：士兵三种步态下脚底的作用力从小到大依次为齐步，正步和跑步(例如，垂直作用力最大幅值分别为76kg，118kg和142kg)。在地面载荷作用下，胫骨中的应力分布是不均匀的。其最大值发生在膝下1／3处．正步和跑步时该处的应力水平分别为110MPa和115MPa。该处正是胫骨骨折临床最常见部位。这些结果给出了胫骨中的应力分布。证明了士兵胫骨应力骨折确是与其中应力水平密切相关的，载荷应力大者正是应力骨折发病率高者。     

在体和离体兔组织射频介电特性的测量

作者制作了同轴线传感器，根据同轴传输线反射原理，建立起计算机控制的生物组织介电测量系统，在６０～３０００ＭＨｚ频率范围对兔器官组织进行了有效在体和离体介电测量，５０只兔器官组织的统计分析结果表明，不同兔器官组织之间介电参数的最大差异可达３０．４％，在体和离体测量得出介电常数之间未见显著性差异，但电导率有频率依赖性的显著差异，因此将人体的离体介电参数延用到实际活体场合时，必须慎重。     

离体组织导热率实验研究

目的生物组织热物性参数是揭示其热传输能力和载热能力及进一步研究生物传热机制的重要指标,导热率是生物组织热物性基本参数之一。方法本文基于等温加热法进行了猪瘦肉、猪脂肪、猪肝等离体组织导热率的实时在位测量和分析：首先选取三种生物组织样本各一块,在其中心位置放置热源,然后离中心不同距离设置五个温度观测点,并测量系统的功率时间变化曲线及各测量点的温度,最后经MATLAB处理获得各点的导热率数据。结果实验结果表明,上述三种组织具有不同的导热率,其中,猪瘦肉的导热率最大,猪肝的导热率次之,脂肪的导热率最小;同一组织内部的不同位置导热率相近。结论本文测量方法和结果对深入开展生物组织传热机制、组织无损温度重构和肿瘤热疗等研究具有重要意义。     

静脉组织碎片镶嵌法离体衬里人工血管的实验研究

目的 寻求一种理想的小口径血管代用品。方法 采用同体双侧对照法,以内径4mm的涤纶人工血管对16条犬进行双侧颈总动脉的间置移植。实验组人工血管用自体颈静脉组织碎片镶嵌后,体外培养7天,术后2、8周观察移植物的形态学和组织学变化。结果 实验组术后2周和8周的通畅率均为87.5％,而同期对照组仅为50％和12.5％,差异显著(P<0.01)。对照组人工血管仅在距吻合口6—8mm范围内发现有内皮细胞生长,而实验组内腔面完全被有序的内皮细胞覆盖。结论 实验说明自体静脉组织碎片离体衬里人工血管,可以有效地加速人工血管的内皮细胞化,有效地改善其近远期通畅率。     

方波激励的生物电阻抗谱自动测试系统

目的为解决多频率方波自动测量生物电阻抗谱的问题,本文设计了一个方波激励的生物电阻抗谱自动测试系统。方法将任意波形函数发生器、仪表放大器和采集卡以及PC组成电阻抗谱自动测试系统,利用PC中的Labview程序分别控制函数发生器和采集卡自动完成激励的产生和数据采集,并将采集到的数据自动保存在PC中,最后利用Matlab程序对数据进行快速傅里叶变换得到阻抗谱。首先对阻抗网络模型进行阻抗谱的仿真,将仿真得到的阻抗谱和理论计算得到的阻抗谱对比;再分别使用此系统和阻抗分析仪对阻抗网络模型进行阻抗测量,将测试得到的阻抗谱进行曲线拟合得到元件值,根据元件值比较测试误差。最后,使用方波激励和稳态正弦激励对酵母细胞悬浮液进行阻抗测量,根据酵母细胞悬浮液的阻抗谱计算介电谱,将得到的介电谱和参考文献中的介电谱作比较,并比较两种激励的测量时间。结果仿真得到的阻抗谱和理论计算得到的阻抗谱一致,验证了方波激励的可行性。测试系统对阻抗网络模型的测试结果和阻抗分析仪的相比误差小于10%,验证了测试系统的正确性。使用方波激励和稳态正弦激励测试酵母细胞悬浮液的阻抗谱,转换成介电谱后,发现其变化规律和参考文献所得结果相符。在100Hz^2MHz的测试范围内,方波激励的测量时间为0.9s,稳态正弦激励的测试时间为1.7s,方波激励的测试速度快。结论本文设计的方波激励的生物电阻抗谱自动测试系统具有自动测试生物阻抗谱的能力,由于使用方波激励,可以兼顾速度和信噪比的要求,实现了计算机控制,可根据实际情况调整激励信号的参数,具有很强的灵活性和可扩展性。     

LPS和雨蛙肽诱导大鼠离体胰腺组织损伤并抑制HSP60蛋白的变化

目的：观察脂多糖（LPS）、雨蛙肽（cerulein）刺激对大鼠离体胰腺组织热休克蛋白60（HSP60）表达的影响。方法: 分离培养大鼠离体胰腺组织,用低、高浓度cerulein (Cer;10-11mol/L,10-5mol/L)或LPS（10 mg/L,20 mg/L）刺激,以生理盐水（NS）作为对照,在刺激前和刺激后1、4h测定胰腺组织的活力（MTT法）、胰蛋白酶原活性肽（TAP）水平（ELISA测定）,培养上清液中白介素6（IL-6）水平（ELISA测定）;并用 real-time PCR和Western blotting分别测定胰腺组织HSP60 mRNA和蛋白的表达。结果: 低、高浓度的cerulein和LPS刺激胰腺组织后1 h,组织的活力与NS对照组比较稍有下降（P>0.05）,刺激4h后,组织活力明显降低（P<0.05）;组织中TAP水平在高浓度cerulein和低、高浓度的LPS刺激下明显升高;其培养上清液中IL-6水平在刺激后1 h变化不明显,4 h时升高,尤其以高浓度的cerulein或LPS作用显著（P<0.05）。胰腺组织HSP60 mRNA和蛋白的表达量随LPS刺激时间的延长和浓度的升高而降低;而低、高浓度的cerulein刺激HSP60 mRNA的表达增加,但蛋白的表达降低,以高浓度、长时间刺激的作用为明显(P<0.05)。结论: LPS及cerulein对离体胰腺组织具有损伤作用,并呈一定时间及浓度依赖性;同时,胰腺组织HSP60蛋白表达降低,提示HSP60细胞保护作用的减弱可能参与该损伤过程。     

离体牙直流电阻特性的研究

作者分别测试了30颗儿童与成年人新鲜离体活髓牙的直流电阻值，发现儿童电阻值显著低于成年人的电阻值，提出利用电阻抗法测量与诊断龋病时必须考虑年龄的影响。     

大鼠离体作功心脏对冠脉压强变化的反应

目的:研究离体作功心脏对其冠脉压强变化的反应.方法:采用分离式离体作功心脏模型.用上海产SJ-42型四导生理记录仪测定生理参数左心室收缩压LVSP,左心室内压上升的最大速率(dp/dt)max,冠脉流量CF,心率HR和心电图ECG.结果:离体作功心脏的工作状态受其冠脉压强变化的影响,当灌注压Pc=9 kPa时,心脏处于最佳状态.灌注压过高或过低均可导致心脏功能减弱.结论:心脏自身存在冠脉压强感受系统,在冠脉压强发生变化时,心脏自主地调节着工作状态.     

Optimal ICSI timing after the first polar body extrusion in in vitro matured human oocytes

BACKGROUND: This study was conducted to investigate the fertilization and embryo development of human oocytes injected at different time intervals after extrusion of the first polar body (PB) following in vitro maturation (IVM) in IVM cycles. Also, we evaluated whether spindle imaging could serve as a tool to determine the optimal ICSI time. METHODS: Oocytes were collected from 43 women with polycystic ovary syndrome. Metaphase I (MI) oocytes after in vitro culture for 24 h from germinal vesicle stage were subjected to ICSI according to time after first PB extrusion. The intervals were: within 1 h (n=38); 1-2 h (n=30); 2-4 h (n=26);4-6 (n=28) and 6-8 h (n=40). In some MI oocytes, viable spindle location was evaluated using Polscope microscopy at different time intervals after first PB extrusion. RESULTS: Fertilization rate of the MI oocytes injected within 1 h after first PB extrusion was low (15.8; 6/38) (P<0.01 versus all other times). In contrast, the fertilization rate was 80, 92.3, 82.1 and 85% for oocytes injected 1-2, 2-4, 4-6 and 6-8 h after first PB extrusion, respectively. Development of good-quality embryos was not significantly different among all the groups. Interestingly, all the oocytes injected within 1 h after first PB extrusion were in Telophase I. CONCLUSIONS: Human oocytes matured in vitro needed at least 1 h after first PB extrusion to complete nuclear maturation. Use of a live spindle imaging system can help to decide the timing of ICSI for oocytes matured in vitro.     

Monocyte mediated modulation of the antibody response in vitro

Human peripheral blood monocytes (PBMC) were isolated by Ficoll-Hypaque density gradient and then fractionated by differential adhesion to plastic surface. Adherent cell-depleted PBMC, non-readherent fraction and firmly adherent fraction so obtained from PBMC, PBMC themselves and a mixture of the above cells, were then sensitized in vitro with sheep erythrocytes (SRBC) so as to produce a primary antigen-dependent, antigen-specific antibody response. It appears that adherent cell-depleted PBMC produce about twice as many haemolytic areas as compared to total PBMC (from 43 to 85). If depleted PBMC are co-cultured with firmly adherent or non-readherent cells, the number of haemolytic areas goes down to 19 or up to 102, respectively. Functional, histochemical, immunochemical and morphological data suggest that the inhibiting firmly adherent fraction is composed of typical phagocytizing cells, while the enhancing cells of the non-readherent fraction are similar to the dendritic cells described in human blood and some lymphoid organs, which do not exhibit active pinocytic activity, but are the principal accessory cells needed to stimulate lymphocyte responses.     

A modified system for in vitro perfusion of isolated renal tubules

A modified system for the in vitro perfusion of isolated tubule segments is presented. The system consists of four holders each of which carries an acrylic cylinder. The acrylic cylinders are used to fix the glass pipettes in a concentric position. The four holders are mounted onto a support consisting of two holding pieces and three steel rods. Three of the holders contain ball-races so that they can slide on the rods with high accuracy and little friction. The holers to which the sylgard pipette and the perfusion pipette are attached are moved by electric motors. Compared with the classical V-track system this modification has the advantage of higher precision. Once the different pipettes are centered, concentricity is maintained even when the pipettes are moved forward or backward. Thus, this equipment facilitates the cannulation of tubules and increases the number of successfull experiments.This study was supported by Deutsche Forschungsgemeinschaft     

The effect of posture change on blood volume,serum potassium and whole body electrical impedance

After standing for 1h, ten subjects (7 male, 3 female) assumed a supine position for a further hour. Whole body bioelectrical impedance increased progressively during the hour spent in the supine position: after 60 min supine the increase was 13(6 to 32). Blood and plasma volumes, estimated from haematocrit and haemoglobin concentration, increased by 8.0(6.7 to 12.4)% and 16.7(12.3 to 20.8)% (median(range)) respectively after 60 min supine. Serum potassium concentration had fallen after 10 min supine (4.1(0.1)mmol 1^–1; mean(SEM)) relative to the standing value (4.6(0.1)mmol 1^–1) and was unchanged thereafter. Serum osmolality (P=0.991) and sodium (P=1.000) and chloride (P=0.998) concentrations remained unchanged throughout the study. The fall in serum potassium concentration in the supine position does not appear to be a simple dilutional effect consequent upon increases in blood and plasma volume as there was no effect of postural change on serum sodium or chloride concentrations.     

Assessment of body composition in the prader-willi syndrome using bioelectrical impedance

The accurate assessment of body composition is of importance in the Prader-Willi syndrome. Many techniques are not applicable due to ethical or practical reasons. However, the bioelectrical impedance technique is a rapid, painless, noninvasive method of estimating total body water and hence, fat-free mass in obese children and adolescents. We have compared estimates of total body water derived from bioelectrical impedance with actual measurements taken, using H₂¹⁸O dilution, in 14 children with Prader-Willi syndrome. Existing equations for predicting total body water from impedance showed a bias to underestimate actual measures of body water. There were positive correlations between the degree of underestimation with age and body fatness. It is possible that changes in body shapes influence bioelectrical impedance measurements in obese individuals, and that a prediction equation based upon a normal population will not be applicable to obese individuals. © 1992 Wiley-Liss, Inc.     

体外人脑胶质瘤电阻抗特性及等效电路

目的 研究人脑胶质瘤的电阻抗特性并建立其等效电路,可为进一步区分人脑胶质瘤和正常脑组织的阻抗特性差异提供依据.方法 利用英国Solartron公司的阻抗分析仪（1260）,采用四端法,在10 Hz ～ 10 MHz范围内,对4例体外人胶质瘤组织进行电阻抗测量.通过分析其频率特性并结合已有的人脑组织的等效电路,建立了体外胶质瘤的等效电路,利用阻抗分析软件Z-VIEW对其进行仿真.结果 体外人脑胶质瘤的阻抗模值在10 Hz～10 MHz范围内随频率的增大而下降,相位角在该范围内随频率的增大而增大.体外人脑胶质瘤组织在10 kHz ～ 10 MHz范围内电阻抗实部比较稳定,其中在10Hz～ 10 kHz范围内,实部随频率的增大而减小.电阻抗虚部在20 kHz ～ 10 MHz范围内较稳定,而在10Hz ～ 20 kHz范围内,虚部随频率增大而增大.样本的等效电路仿真曲线与实际曲线相比较,等效电路模型能较好地反映体外人脑胶质瘤的电阻抗特性.结论 体外人脑胶质瘤与已知的正常脑组织的电阻抗特性及等效电路差别明显,这为探索生物电阻抗技术应用于区别胶质瘤与正常脑组织的临床应用提供了研究基础.     

Seasonal variation of IgE synthesis in vitro by human peripheral blood mononuclear cells

Seasonal variations in IgE antibody synthesis in vitro were studied in cultures of blood mononuclear cells (MNC) from 11 pollen allergic individuals. The IgE levels were significantly higher in two summer seasons than in the winter and spring between them. Net synthesis was confined to the summer in all but one of the patients. All the IgE in the cultures outside the pollen season represented preformed IgE which was present mainly (59%) in the monocyte fraction. Thus, preformed IgE seems to persist in monocytes at times when there is little de novo synthesis of IgE.     

Successful delivery after the transfer of twice-vitrified embryos derived from in vitro matured oocytes: a case report

We report here the first case of successful pregnancy and delivery after the blastocyst transfer of twice-vitrified embryos produced following in vitro maturation (IVM) and ICSI. The patient received 5000 IU hCG on day 12 of the treatment cycle, and oocyte retrieval was carried out 36 h after hCG injection. A total of 22 immature oocytes were obtained. Following incubation for 26 h in IVM medium, 15 oocytes (68.2%) reached metaphase II stage. In total, 13 oocytes (86.7%) were fertilized after ICSI with the husband's sperm, and 11 embryos at the pronuclear stage and two cleaved embryos on day 2 were vitrified because of thin endometrial thickness. Eight cryopreserved embryos at the pronuclear stage were warmed and cultured until the day 3 stage. Three embryos were transferred, and three embryos were twice vitrified. Unfortunately, these transferred embryos did not implant. Three twice-vitrified embryos were rewarmed and cultured until the day 5 stage, and two embryos were transferred. The second transfer attempt of twice-vitrified embryos resulted in the full-term delivery of a healthy infant. This case report demonstrates that twice-vitrified embryos, developed using an IVM protocol, retain the developmental competence for full-term, healthy infants.     

Standardisation of bioelectrical impedance analysis for the estimation of body composition in healthy paediatric populations: a systematic review

Background: Bioelectrical impedance analysis (BIA) requires a high degree of standardisation in order to ensure valid and reproducible impedance measurements. The overall aim of this review was to study the degree to which BIA papers conducted in healthy paediatric populations (aged 0–17 years) were standardised.

Methods: Literature was identified on the basis of a systematic search of internationally-recognised electronic databases and hand searching of the reference lists of the included papers in order to identify additional relevant papers. The review was limited to lead-type BIA devices for whole-body, segmental- and focal impedance measurements. In total, 71 papers published between 1988 and 2016 were included.

To evaluate the degree of standardisation of the papers, a recently published review detailing critical factors that may impact on BIA measurements in children was used as a model for structuring and extracting data.

Results: There was a general lack of BIA standardisation, or its reporting, in the papers under review, which hinders comparison of data between studies and could potentially lead to erroneous measurements.

Conclusions: If the BIA technique should be accepted clinically for routine use in paediatric populations, there is a need for an increased focus on the importance of improved standardisation and its reporting in future studies. Consequently, this review contains recommendations for performing and reporting BIA measurements in a standardised manner.