应用Cole-Cole公式分析蛙血液细胞介电谱

利用Cole-Cole公式对10^4～10^8Hz频率段的蛙血液细胞介电谱进行了曲线拟合分析，建立了蛙血液细胞Cole-Cole参数：高频段相对介电常数εh=60，第一相对介电增量△εl=4900，第二相对介电增量△ε2=1200，第一特征频率fl=0．2MHz，第二特征频率f2=2．4MHz，第一相位角βl=0．92，第二相位角β2=0．93，低频段电导率εl=3．38ms／cm。     

骨骼肌细胞的介电弛豫特性

在100Hz～100MHz频率范围内,利用非线性数值计算和曲线拟合分析,验证了蛙离体骨骼肌细胞的介电弛豫特性满足Cole-Cole公式(误差≤3.45%),通过频域介电谱、Cole-Cole图、介电损耗因子和介电损耗角正切频率谱的曲线拟合分析,确定了蛙骨骼肌细胞的Cole-Cole介电参数:高频段相对介电常数εh=78,第一相对介电增量△ε1=113000,第二相对介电增量△ε2=45000,第一特征频率fc1=9 kHz,第二特征频率fc2=158 kHz,第一相位角β1=0.881,第二相位角β2=0.984,低频段电导率κL=0.55mS/cm,常数A=35,常数m=1.08.     

骨骼肌介电行为的理论模型仿真

在 10 0 Hz～ 10 0 MHz范围内 ,应用椭圆壳介电理论模型 ,经过模拟仿真蛙骨骼肌细胞的介电行为 ,确定了蛙骨骼肌细胞的椭圆壳模型各相参数。为将来对骨骼肌疲劳、肌营养不良和肌肉萎缩等病症的模型分析奠定理论基础。     

0.1 MHz～100 MHz大鼠血液细胞的介电响应

目的：确立正常大鼠血液细胞对0．1MHz-100MHz交流电场的介电响应的数据特征。材料与方法：取10只雄性Sprague-Dawley大鼠全血，利用Agilent4294A阻抗分析仪测量了26个全血细胞悬浮液样本的交流阻抗，通过频域介电谱和Cole-Cole图的数据分析，确立了正常大鼠血液细胞对交流电场的介电响应的数据特征。结果：在0．1MHz-100MHz频率范围内，大鼠血液细胞的介电常数和电导率具有电场频率的依赖关系，主要表现在具有两个中心特征频率的介电弛豫：第一介电弛豫约发生在fc1=2MHz，第二介电弛豫约产生在fc2=3MHz。结论：交流阻抗技术可以观察血液细胞的介电响应特性。     

频域阻抗法研究细胞介电特性

对生物细胞介电特性的研究是生物医学物理学公认的前沿重点课题之一.本文介绍如何采用宽频域交流阻抗技术研究细胞介电特性的原理和方法,以及在细胞介电谱的基础上,如何通过非线性数值计算建立细胞的数学模型和物理模型.本文以蛙骨骼肌细胞为例,在100Hz～100 MHz范围内,应用阻抗分析仪测量了细胞交流阻抗,通过细胞介电谱、Cole-Cole图、介电耗损因子频率谱、介电损耗角正切频率谱等方式,分析了骨骼肌细胞介电特性的数据特征;最后使用Cole-Cole模型和椭圆壳介电理论,建立了骨骼肌细胞的数学模型和物理模型,为今后利用数理模型方法分析骨骼肌疲劳、骨骼肌萎缩等奠定了基础.     

人血液细胞介电谱的实验研究

在0．01～100MHz范围内，测量人血液细胞的介电谱，确立人血液细胞对交流电场的介电响应的数据特征。利用频域阻抗技术测量了正常人血液细胞交流阻抗，绘制细胞的介电常数和电导率与电场频率的关系曲线。建立了人血液细胞的介电谱和Cole—Cole图，明确了人血细胞的介电频响的数据特征。在射频电场中，人血液细胞的介电常数和电导率具有频率依赖性，表现为具有两个特征频率的介电弛豫：第一介电弛豫发生在fc。为1．42MHz，第二介电弛豫产生在fcz为3．32MHz。     

人血液介电谱Cole-Cole数学模型的解析

通过Cole-Cole方程的数值计算,对人血液介电谱实验数据进行曲线拟合的残差分析,建立人血液Cole-Cole数学模型参数。在104～108 Hz频率范围,使用Agilent 4294A阻抗分析仪测量30人70例全血导纳,并利用Cole-Cole方程的非线性数值计算,对实测数据进行曲线拟合,计算曲线拟合的残差数值。人血液介电谱的Cole-Cole数学模型参数:高频极限介电常数εh=45±5;第一弛豫介电增量Δε1=6 200±350、第一特征频率fC1=(500±5)kHz、第一弛豫分布系数β1=0.86±0.06、第二弛豫介电增量Δε2=990±310、第二特征频率fC2=(2.7±0.1)MHz、第二弛豫分布系数β2=0.975±0.015、低频极限电导率κl=(4.15±0.85)mS/cm。人血液细胞介电行为可以通过介电频谱、Cole-Cole图、介电损耗因子频谱、电导率虚部频谱及损耗角正切频谱等5个频谱进行表征,建立Cole-Cole模型参数。     

正常人血小板介电谱的实验研究

在100KHz～110MHz范围内,测量人血小板的介电谱,分析了人血小板对交流电场的介电响应的数据特征。利用频域阻抗技术首次测量了正常人血小板交流阻抗,绘制血小板的介电常数和电导率与电场频率的关系曲线。建立了人血小板的介电谱和Cole-Cole图,明确了人血小板的介电频响的数据特征。在射频电场中,人血小板的介电常数和电导率具有频率依赖性,血小板介电谱具有两个特征频率:第一特征频率fC1为6.66MHz,第二特征频率fC2为9.81MHz。     

正常人血小板射频段介电响应测量

目的 在射频段测量正常人血小板介电谱,建立血小板对交流电场介电响应的数据特征.方法 利用频域阻抗技术测量人血小板交流阻抗,经过介电谱、Cole-Cole图、介电损耗因子△ε"、导电率虚部△κ"、介电损耗角正切△tgδ等频谱,明确人血小板介电频响的数据特征.结果 在射频电场中,人血小板的介电常数和电导率具有频率依赖性;血小板介电响应具有两个中心特征频率:第一中心特征频率fC1=6.66 MHz,第二中心特征频率fC2=9.81 MHz.结论 交流阻抗技术能够测量血小板射频段介电响应.     

正常人血小板射频段介电响应测量

目的在射频段测量正常人血小板介电谱,建立血小板对交流电场介电响应的数据特征。方法利用频域阻抗技术测量人血小板交流阻抗,经过介电谱、Cole-Cole图、介电损耗因子Δε”、导电率虚部Δκ”、介电损耗角正切Δtgδ等频谱,明确人血小板介电频响的数据特征。结果在射频电场中,人血小板的介电常数和电导率具有频率依赖性;血小板介电响应具有两个中心特征频率:第一中心特征频率fC1=6.66MHz,第二中心特征频率fC2=9.81MHz。结论交流阻抗技术能够测量血小板射频段介电响应。     

Heat and water losses from burnt skin

A thermal-modelling technique is employed to predict temperature distributions and the resulting heat and water losses from skin with various degrees of burn to the environment. Consideration is given to molecular diffusion of heat and water, capillary blood circulation, metabolic heat and water generation, and heat and water exchange with the environment through convection, radiation and evaporation. The pathological effect of burn is included by changing mass diffusivity. Numerical results for water losses for various degrees of burn are obtained, together with temperature profile at the burn site. The results of above findings agree with experimental data.     

老年髋部骨折围手术期失血量的临床观察

目的通过观察髋部骨折围手术期血红蛋白水平改变,总结髋部骨折患者围手术期隐形失血量、总失血情况,探讨围手术期失血量的危险因素。方法选择北京市顺义区医院骨科2011年12月至2013年12月老年髋部骨折患者,记录患者一般情况,包括性别、年龄、并发症、骨折类型,手术方式（分别按照空心钉、关节置换、动力性髋螺钉和髓内钉的标准流程操作）、抗凝药物使用情况、出血量、手术时间等,根据患者血红蛋白水平波动、输血量计算患者隐形失血量、总失血量,通过方差分析及多因素线性分析计算围手术期间总失血量的独立危险因素。结果 2011年12月至2013年12月共有161例老年髋部骨折患者入选,经单因素方差分析及多因素线性回归分析,发现服用抗凝药物（均P=0.000）、手术方式（P=0.000,P=0.004）是围手术期出血量较多的独立危险因素。结论老年髋部骨折围手术期隐形失血量远远大于术中出血量,髓内钉术中出血量较关节置换、动力性髋螺钉（DHS）系统少,但隐形失血量、总失血量较其他三种手术方式明显增多,此外,服用阿司匹林等抗凝药物可增加术中出血量、隐形失血量及总失血量。     

Limitation of Conventional Audiometry in Identifying Hidden Hearing Loss in Acute Noise Exposure

PurposeThe concept of hidden hearing loss can explain the discrepancy between a listener''s perception of hearing ability and hearing evaluation using pure tone audiograms. This study investigated the utility of the suprathreshold auditory brainstem response (ABR) for the evaluation of hidden hearing loss in noise-exposed ear with normal audiograms.Materials and MethodsA total of 15 patients (24 ears) with normal auditory thresholds and normal distortion product otoacoustic emissions were included in a retrospective analysis of medical records of 80 patients presenting with histories of acute noise exposure. The control group included 12 subjects (24 ears) with normal audiograms and no history of noise exposure. Pure tone audiometry and suprathreshold ABR testing at 90 dB peSPL were performed. The amplitudes and latencies of ABR waves I and V were compared between the noise-exposed and control groups.ResultsWe found no significant difference in the wave I or V amplitude, or the wave I/V ratio, between the two groups. The latencies of ABR wave I, V, and I-V interpeak interval were compared, and no significant intergroup difference was observed.ConclusionThe results suggest that either hidden hearing loss may not be significant in this cohort of patients with acute noise exposure history, or the possible damage by noise exposure is not reflected in the ABRs. Further studies are needed to inquire about the role of ABR in identification of hidden hearing loss.     

The critical level of water deficit causing a decrease in human exercise performance: a practical field study

To analyse the critical level of water deficit which causes a decrease in aerobic and anaerobic exercise performance, a step test score (STS) and 10 s maximal anaerobic power (MAP) output during cycling exercise were measured in two experiments (Ex-1, n=7, and Ex-2, n=9), before and after baseball practice, using subjects who played regularly. The measurements in both Ex-1 and Ex-2 were repeated under four conditions of fluid ingestion (FI) (FI of 80%, 60%, 40%, and 20% of the total sweat loss) on hot summer days. The subjects were allowed free access to a sports beverage, maintained at 10–15°C, within any given FI condition during the exercise. The [mean (SEM)] duration of the exercise and the environmental conditions (wet bulb globe temperature) were similar between Ex-1 [3.52 (0.14) h and 29.2 (0.6)°C, respectively] and Ex-2 [3.82 (0.12) h and 29.2 (0.4)°C, respectively]. In both Ex-1 and Ex-2, the loss of body mass (Δm _b) increased significantly as FI decreased. In Ex-1, the STS significantly decreased (P<0.05) at values of Δm _b in excess of 2.4 (0.2)% (40%FI). In Ex-2, the MAP remained unchanged at values of Δm _b up to 2.5 (0.3)% (40%FI), while the MAP significantly decreased (P<0.05) at values of Δm _b of 3.9 (0.2)% (20%FI). These results suggest that there is a critical level of water deficit at which a decrease in aerobic and anaerobic performance occurs, and that aerobic performance may be more adversely influenced by dehydration than anaerobic power output during exercise-induced dehydration. Electronic Publication     

THE FREQUENCY AND MECHANISM OF LOSS OF HETEROZYGOSITY ON CHROMOSOME 11q IN BREAST CANCER

Loss of heterozygosity (LOH, allele loss) occurs frequently on the long arm of chromosome 11 in breast cancer. Seventy-one paired tumour/normal DNA samples from breast cancer patients under 50 years old were studied for allele loss at four microsatellite loci on 11q: D11S29 (11q23.3), NCAM (11q22–q23), D11S968 (11qtel), and D11S1313 (11qcen). The maximum frequency of LOH (≈35 per cent) was found at the D11S29 and NCAM loci. This result is consistent with previous studies and the frequency of allele loss is moderate to high compared with the usual baseline of 0–20 per cent. In most of the cases studied, LOH on chromosome 11q could be accounted for by one of two mechanisms. Either chromosomal non-disjunction had occurred, or sequences stretching from the telomere at least as far as NCAM had undergone deletion or mitotic recombination. These results suggest that a putative tumour suppressor gene is most likely to exist near 11q22–q23. There was a very low frequency of microsatellite instability in the tumours. An association was found between lack of progesterone receptor (PgR) expression and LOH at NCAM , suggesting that deletion of sequences on 11q may prevent high levels of PgR expression in some cases.     

Placental thrombosis in experimental anticardiolipin antibodies-mediated intrauterine fetal death

PROBLEM: Anticardiolipin (aCL) antibodies are associated with stillbirths, recurrent miscarriages and recurrent in vitro fertilization implantation failure in women. Previous animal studies have demonstrated that these antibodies can cause early fetal demise and implantation failure in mice, but most previous studies have not allowed the immunized mice to proceed to the full term of gestation. METHOD OF STUDY: Mice were immunized with either cardiolipin alone or cardiolipin in combination with beta2-glycoprotein I (beta2GPI) and have studied the effects of these antibodies on pregnancies which were allowed to progress to term. RESULTS: Immunization with cardiolipin alone induced significant levels of anticardiolipin antibodies in mice, but immunization with a combination of cardiolipin and beta2GPI produced even higher levels of antibodies. Mice with elevated levels of anticardiolipin antibodies had poor pregnancy outcomes. This study confirms previous results that anticardiolipin antibodies cause early pregnancy losses and also demonstrates that these antibodies cause stillbirth-like late fetal demise. This study further demonstrated that very high levels of anticardiolipin antibodies cause intrauterine death by facilitating the thrombotic episode in placenta. CONCLUSIONS: The present study concludes that the possible mechanism involves in stillbirth of aCL is possibly because of the thrombotic events of placenta.     

24-h evaporative and sensible heat losses in relation to ambient humidity at 24 °C in clothed human subjects

The effect of ambient humidity on the energy expenditure of clothed subjects was investigated. Fifty-six healthy men and women, weighing about 65 kg, spent 24 h in a large human calorimeter at 24 °C and performed either of two fixed activity programmes. The ambient humidity varied between experiments from 3 to 11 g m^-3. The sensible heat output did not vary significantly with humidity but the evaporative heat loss decreased by about 1.5 W for each g m^-3 increase in humidity.     

Does Depression Reduce the Effectiveness of Behavioral Weight Loss Treatment?

Limited evidence suggests that depression is associated with poorer outcomes in behavioral weight loss programs; however, people with major depression are typically excluded from weight loss intervention trials. This study examined the effect of depression on women's participation and weight loss in behavioral treatment. Non–treatment seeking obese women over 40 years of age with major depressive disorder (MDD, n = 65) and without MDD (n = 125) were recruited into a 26-session group intervention. Primary analyses compared participants' mean weight change from baseline to 6 and 12 months; at 6 months, women with MDD lost a mean of 3.8 kg vs 4.3 kg for women without MDD (t = 0.54, p = .59). At 12 months, women with MDD lost 3.0 kg and women without MDD lost 3.6 kg (t = 0.44, p =.66). Women who attended at least 12 treatment sessions lost more weight than women who attended fewer sessions, regardless of depression status (ie, there was no significant interaction between depression and session attendance). Results suggest that depression should not be an exclusion criterion for weight loss intervention programs.     

Bronchial response to breathing dry gas at 3.7 MPa ambient pressure

In diving, pulmonary mechanical function is limited by the increased density of the gas breathed. Breathing cold and dry gas may cause an additional increase in airways resistance. We have measured forced vital capacity, forced expired volume in 1 s (FEV₁) and forced midexpiratory flow rate (FEF_25%–75%) before and after breathing dry or humid gas at 29–32°C during a standardized exercise intensity on a cycle ergometer at an ambient pressure of 3.7 MPa. The atmosphere was a helium and oxygen mixture with a density of 6.8 kg · m^–3. Six professional saturation divers aged 26–37 years participated in the study. There were no significant differences in convective respiratory heat loss between the exposures. The mean evaporative heat loss was 67 W (range 59–89) breathing dry gas and 37 W (range 32–43) breathing humid gas, corresponding to water losses of 1.7 g · min^–1 (range 1.5–2.2) and 0.9 g · min^–1 (range 0.8–1.1), respectively. There was a significant reduction in FEV₁ of 4.6 (SD 3.6)% (P<0.05), and in FEF_25%–75% of 5.8 (SD 4.7)% (P<0.05) after breathing dry gas. There were no changes after breathing humid gas. By warming and humidifying the gas breathed in deep saturation diving bronchoconstriction may be prevented.