生物组织复电阻抗频谱测量及电阻抗断层成像系统的研究

作者在离体时间对复阻抗频谱的影响、在体组织复阻抗频谱测量以及血细胞压积对血液复阻抗频谱的影响、静态电阻抗断层成像 （EIT）重构算法、实时 EIT系统及其成像等方面进行了探索性研究 ,通过以上研究进一步证实了阻抗方法在医学研究中的重要性 ,并得到了如下提示性结论 :1在体动物组织缺血后短期内复阻抗频谱发生的变化主要原因可能在于缺血引起的细胞外液成分的变化 ;2离体动物组织复阻抗频谱随离体时间发生的变化主要可能是由于细胞膜活性的改变引起 ,其机制有待进一步深入研究 ;3血液中血细胞含量是血液复阻抗频谱特性变化的主要原因 ,血细胞含量越高 ,复阻抗实部越大 ,虚部最大值也越大 ;血液的特征频率与血细胞含量基本无关 ,从而提示这一特性与血细胞自身活性及状态有关 ;4EIT方法为一种观察微小阻抗分布扰动的敏感方法 ,初步的成像实验提示这一成像方法可以被用来诊断血流异常的病变 ,并能被用于长时间图像监护。     

血液复阻抗频率特性的测量

本研究构造了用于测量血液复电阻抗频率特性的测量系统,测量了不同压积的血液复电阻抗频率特性,并根据频率响应分析方法对测量结果进行的血液复电阻抗讨论。本研究为生物复阻抗测量提供一种方法。     

血液复阻抗频率特性的测量

本研究构造了用于测量血液复电阻抗频率特性的测量系统,测量了不同压积的血液复电阻抗频率特性,并根据频率响应分析方法对测量结果进行了分析、讨论。本研究为生物复阻抗测量提供一种方法。     

在体动物心肌损伤模型述评

讨论了目前在体心肌损伤动物模型建立的基本原理和方法,同时比较了各种模型的用途与优缺点,为研究者选择合适的动物模型提供了依据.     

实时电阻抗断层成像系统对离体心脏充盈模型成像的初步结果

目的 :探讨电阻抗断层成像技术 （EIT）在心血管系统成像中的潜在应用价值 ,同时通过对离体动物器官的成像实验改进已有的成像实验系统。方法 :用自行设计的实时电阻抗断层成像系统 ,对离体动物心脏充盈模型进行EIT的实验。结果 :EIT图像对离体心脏充盈模型中各腔室的电阻抗分布的变化敏感。结论 :EIT在心血管系统中有应用前景     

显微磁共振成像在神经精神疾病模型动物在体研究中的应用

妻人体的复杂性决定了大量疾病的研究工作要通过动物模型在体动态研究来实现.显微磁共振成像技术的发展及其在人类神经精神疾病动物模型中的应用,从在体神经解剖信息到特定分子靶点的测定,为推动神经精神病学研究的深入和发展开辟了新的途径.     

绝对不应期电刺激对正常兔在体心脏心功能的影响

20世纪60年代的成对兴奋性起搏对心力衰竭的治疗，因较大的心律失常风险性而被弃用。多部位心室起搏对心力衰竭的治疗仅限于宽QRS波的病人群体，且多部位心室起搏不增加收缩力。一种全新的心脏收缩调节(cardiac con—tractility modulation，CCM)方法，即在心肌兴奋的绝对不应期发放电刺激来增强心肌收缩功能的方法近来颇受关注。然而，新近开始的这项研究处于起始阶段，     

犬在体心肌跨室壁复极不均一性的研究

目的　探讨犬在体心肌是否存在跨室壁复极不均一性。方法　用单相动作电位记录技术 ,同步记录 10只开胸犬在体心脏正常及心率减慢状态下心外膜心肌 (epicardium ,Epi)、中层心肌(midmyocardium ,Mid)及心内膜心肌 (endocardium ,Endo)单相动作电位 (monophasicactionpotential,MAP) ,测量单相动作电位时程 (MAPD)并比较其差异。结果　在心动周期 30 0ms时 ,Epi、Mid及Endo的MAP复极化达到 90 %的单相动作电位时程 (MAPD90 )分别为 (2 0 8 6 7± 44 37)ms、(2 0 9 17± 38 6 2 )ms、(2 0 3 5 0± 33 84)ms,在体三层心肌MAPD无明显差异 ;心动周期增加至 2 0 0 0ms时 ,三层心肌MAPD呈慢频率依赖性延长 ,Epi、Mid及Endo的MAPD90 分别为 (32 9 90± 31 90 )ms、(36 9 90± 35 0 9)ms、(317 2 0± 40 2 7)ms,其中Mid的MAPD90 延长最为显著 ,与Epi及Endo相比 ,差异有显著性 (P <0 0 5 )。结论　犬在体心肌存在明显慢频率依赖性的跨室壁复极不均一性 ,而Mid细胞的电生理特征可能是导致这一差异的基础。     

细针型共聚焦激光显微内镜在体成像的动物实验研究

目的 探索细针型共聚焦激光显微内镜（nCLE）对动物腹腔组织及脏器成像的可行性。方法 选取实验家兔的大网膜、肝脏、胰腺、腰大肌（骨骼肌）为研究对象,nCLE经由19 G穿刺针进入其内部分别进行成像,观察各腹腔组织及脏器的成像特征,并留取清晰的nCLE图像。最终将nCLE图像与病理组织学结果相比对。结果 5只实验家兔腹腔组织及脏器的nCLE成像均成功完成,并清晰显示大网膜、肝脏、胰腺、腰大肌（骨骼肌）的细胞、腺体、微血管等显微结构,其nCLE图像具有特征性。各腹腔组织及脏器nCLE图像与病理组织学具有良好的一致性。结论 利用nCLE对腹腔组织及脏器成像具有可行性。     

体尺和体重测量在新生儿脐静脉置管深度的随机对照研究

目的观察体尺和体重测量在新生儿脐静脉置管深度的应用成效。方法选取从2018年3月-2019年3月收治于我院的100例接受脐静脉置管处理的低体重新生儿作为研究对象,随机分为体尺测量与体重测量两组,将前者测量方式记作A组,后者测量方式记作B组,每组50例,比较两组新生儿脐静脉置管效果。结果A组与B组新生儿预计置管深度与初次置管成功率之间差异没有统计学意义(P>0.05),A组置管准确率为86.0%,显著大于B组置管准确率,两者之间差异存在统计学意义(P<0.05);A组新生儿置管引起的并发症中,败血症3例、肝静脉栓塞0例、坏死性肠炎1例,总发生率是8.0%,B组新生儿在置管之后出现败血症2例、肝静脉栓塞1例、坏死性肠炎2例,总发生率为10.0%,差异没有统计学意义(P>0.05)。结论新生儿脐静脉置管深度的测量中,使用体尺测量方法较体重测量方法可以提高测量准确率,安全可靠,应该成为可靠的脐静脉置管深度评估思路。     

In vitro measurement accuracy of three-dimensional ultrasound

OBJECTIVES: We sought to validate distance and volume measurements in three-dimensional (3-D) ultrasound images. BACKGROUND: Even with the latest equipment, it is not known how accurate 3-D echocardiographic measurements are. METHODS: Six models were imaged in ethanol solution and two within a tissue phantom using a mechanical rotation device rotating in 1 degrees intervals and a real-time 3-D scanner. Distance and volume measurements (n = 60) were performed in two-dimensional (2-D) and 3-D images using TomTec and InViVo software. RESULTS: Distance measurements had a mean total error between 1.12% and 2.31% for Acuson (2.5 MHZ, 3 MHZ, and 4 MHZ) and Hewlett Parkard (HP) fusion frequencies h and m, HP fusion harmonic B in the axial, and between 3.5% and 4.9% in the lateral dimension. HP Harmonic A and B, Volumetrics (2.5 MHZ), and HP fusion Harmonic A exhibited significantly higher differences to reality with a mean difference between 5.1% and 8.9% in the axial and between 6.2% and 7.9% in the lateral direction. Axial 2-D measurements were not different from real dimensions except Volumetrics model 1. In the lateral axis, all imaging modalities were different from reality except the fusion harmonic modus B. Using the HP fusion frequency h and HP fusion Harmonic B-mode, volume measurements in 3-D images significantly underestimated reality, while Acuson's fundamental frequency 3.5 MHZ was not different from real volumes. CONCLUSION: Three-dimensional visualization using different ultrasound settings results in different accuracy.     

Variability in quantitative measurement of the same segment with two different intravascular ultrasound systems: in vivo and in vitro studies.

We evaluated two different intravascular ultrasound (IVUS) systems, Atlantis and Intrafocus, to verify their accuracy and reproducibility. In an in vivo study on 20 consecutive patients with coronary artery diseases, the minimum lumen diameter (MLD), vessel diameter, lumen area (LA), vessel area, plaque area, and area stenosis rate (% AS) were respectively measured. In an in vitro study, MLD and LA were measured in four metal tubes with different diameters. All of the measured values except for % AS by Atlantis were significantly larger than the values obtained with Intrafocus. Nonuniform rotational distortion (NURD) was estimated as 34% in Atlantis and 1% in Intrafocus. The measurements by Atlantis were larger than the true values while the measurements by Intrafocus were less than the true values in all four metal tubes. These findings suggest that we should clearly avoid the use of different IVUS systems in the same study.     

In vivo measurement of colonic butyrate metabolism in patients with quiescent ulcerative colitis

BACKGROUND: Butyrate, a short chain fatty acid produced by bacterial fermentation, is a major fuel source for the colonocyte. In vitro work has shown that ulcerative colitis may be characterised by a metabolic defect in colonocyte butyrate oxidation. AIMS: To investigate the rate of metabolism of rectally administered butyrate in patients with quiescent colitis. METHODS: [1-(13)C]-butyrate enemas were administered to 11 patients with long standing quiescent ulcerative colitis and to 10 control patients. The rate of production of (13)CO(2) in exhaled breath over four hours was measured by isotope ratio mass spectrometry combined with indirect calorimetry in order to measure CO(2) production. This allowed calculation of the patients' resting energy expenditure and respiratory quotient. RESULTS: Over a four hour period, 325 (SEM 21) micromol (13)CO(2) was recovered in breath samples from the colitis group compared with 322 (17) micromol from the control group (NS). The respiratory quotient of the colitic group was significantly lower than that of the control group. CONCLUSION: There was no difference in the rate of metabolism of butyrate between the two groups. It is unlikely that there is a primary metabolic defect of butyrate metabolism in patients with quiescent ulcerative colitis.     

In vitro investigations of jet-pulses for the measurement of respiratory impedance in newborns.

The aim of this in vitro study was to investigate the measuring range and accuracy of a miniaturized equipment for respiratory impedance (Zrs) measurements in newborns using jet-pulses. Brief flow pulses (peak flow=16 L x min(-1), width=10 ms) were generated by a jet-generator consisting of a solenoid valve and an injector, situated between pneumotachograph and outflow resistance. Serially arranged resistance-inertance-compliance (R-I-C) lung models (RM=1.3-6.4 kPa x L(-1) x s, CM=7.4-36.9 mL x kPa(-1), IM=1.5 Pa x L(-1) x s2) were used to measure the real and imaginary part of Zrs between 4 and 50 Hz and to determine R, C and I by means of the method of least squares. The median errors for R, C and I were -0.1 kPa x L(-1) x s (-2%), 2.4 mL x kPa(-1)(13%) and -0.2 Pa x L(-1) x s2 (-13%) for measurements without breathing signals and 0.11 kPa x L(-1) -s (3%), 3 mL x kPa(-1) (16%) and 0.28 Pa x L (-1) x s2 (19%) in mechanically ventilated models. During spontaneous breathing the influence of the breathing flow on Zrs was negligible. The equipment did not show any nonlinearity when different pulse amplitudes were used (Vmax=13-22 L x min(-1)). The investigations have shown that jet-pulses allow reliable measurements of respiratory impedance and have the potential to provide valuable information about lung mechanics in spontaneously breathing and mechanically ventilated newborns. The developed measuring head has a low apparatus dead space, is easy to disinfect, has standard connections and can be used as the T-piece in a ventilator circuit.     

In vivo administration of granulocyte colony-stimulating factor promotes neutrophil survival in vitro

Abstract: We recently showed that recombinant human granulocyte-colony stimulating factor (rhG-CSF) maintained the viability of human neutrophils in incubation for up to 72 hours. However, it is not known whether rhG-CSF can enhance neutrophil survival in in vivo situations. To clarify this issue, we investigated neutrophil survival in vitro following in vivo injection of rhG-CSF. Neutrophils were obtained from 4 pediatric patients with malignancies and healthy adult volunteers before and after rhG-CSF administration. Neutrophils obtained before rhG-CSF treatment started to undergo apoptosis after 24 h of incubation. In contrast, the survival of neutrophils drawn after rhG-CSF administration increased by approximately 24 h. Concomitantly, the appearance of typical ladder-like DNA fragmentation was delayed. Such an increase in neutrophil survival was inhibited by coincubation with either H 7 (10 μmol/1) or H 8 (20 μmol/1), which worked as protein kinase C inhibitors. Although our study did not measure neutrophil survival in vivo directly, it provides us with further evidence that rhG-CSF may function to prolong neutrophil life expectancy in vivo.     

In vitro and in vivo stability of diluted recombinant factor VIII for continuous infusion use in haemophilia A

Summary.  Factor VIII (FVIII) replacement by continuous infusion (CI) is used postoperatively or after significant bleeding. For young paediatric patients, CI may require FVIII dilution. Variable stabilities of diluted full-length recombinant FVIII Kogenate^® FS (KG-FS) have been reported under different storage conditions. We investigated the recovery and stability of diluted KG-FS in vitro and in vivo . Kogenate^® FS was diluted to 50–120 U mL⁻¹ and its recovery and stability in glass vials or polypropylene syringes was determined. Furthermore, stability of KG-FS diluted to 80 U mL⁻¹'administered' via single- and double-pump mock CI systems was tested. Finally, the in vivo stability of KG-FS diluted to ∼60 U mL⁻¹ and administered postsurgically by CI with the double-pump to a paediatric patient with severe haemophilia A undergoing implantable venous access device placement was investigated. Initial KG-FS dilution resulted in a 10–20% FVIII loss; a further 25–30% loss occurred over 72 h in vials or syringes. With the double-pump, 1 h recovery was 35%, increasing to 80% by 24 h; the initial losses were because of the Y-infusion of a 10-fold larger volume of saline concomitantly with the FVIII. In vivo , CI resulted in stable FVIII activity levels within the target range. These in vitro results are important for the generation of CI guidelines for diluted KG-FS in the paediatric haemophilic population. That FVIII losses occur upon dilution and with the double-pump does not preclude use of diluted KG-FS. Indeed, stable FVIII levels were maintained when diluted KG-FS was administered by CI with the double-pump to a paediatric patient postsurgically.