人体脉搏的测量与分析

人体脉搏信息反映了人体内部各器官的健康状态。本文介绍了一种用压力传感器实现脉搏测量的系统设计及测量方法,并对测量的脉搏信号进行了频谱分析和讨论,其分析结果与人体生理状况是相符的。     

Validity and reproducibility of arterial pulse wave velocity measurement using new device with oscillometric technique: A pilot study

Background  

Availability of a range of techniques and devices allow measurement of many variables related to the stiffness of large or medium sized arteries. There is good evidence that, pulse wave velocity is a relatively simple measurement and is a good indicator of changes in arterial properties. The pulse wave velocity calculated from pulse wave recording by other methods like doppler or tonometry is tedious, time-consuming and above all their reproducibility depends on the operator skills. It requires intensive resource involvement. For epidemiological studies these methods are not suitable. The aim of our study was to clinically evaluate the validity and reproducibility of a new automatic device for measurement of pulse wave velocity that can be used in such studies.     

脉搏波时标对臂踝脉搏波传播速度测量的影响

臂踝脉搏波传播速度(brachial-ankle pulse wave velocity,baPWV)测量是一种便捷、无创的方法,可用于人体动脉硬化度的评估,在临床和科学研究中广泛应用于血管早期病变的筛查和心血管系统风险的评估。本文设计开发了人体上臂和踝部脉搏波波形采集系统,并利用该系统对59名健康成年人进行实验,研究了目前三种最常用的脉搏波时标(pulse timing mark,PTM)定义方法对baPWV测量的影响。实验结果表明,选用不同的PTM方法所测得的baPWV结果具有显著的差异性(P0.001)。而且,PTM方法的不同还影响到了baPWV与年龄、血压的相互关系。     

Parameters describing the pulse wave

Pulse wave analysis permits non-invasive assessment of arterial elasticity indices. The contour varies in different parts of the circulation. It depends on physiological or pathophysiological conditions of the organism. The pathological events like arteriosclerosis or diabetes have a primary effect to the artery elasticity. Hypertension or some heart diseases also influence the pulse wave velocity and resulted in earlier wave reflections. There are several methods of pulse wave measurements based on different principles and depending on the type of measured pulse wave. The evaluation parameters can be assessed from the time domain, derivations, velocity or frequency domain. The main aim of this review article is to offer a recent overview of pulse wave measurement parameters and main results obtained. The principles of pulse wave measurement and current experience in clinical practice are shortly discussed too.     

Performance enhancement of polyaniline-based polymeric wire biosensor

We demonstrate here the performance enhancement of polyaniline-based biosensor using screen-printing technology and pulse mode measurement technique. Screen-printed silver electrodes were made on a nitrocellulose membrane and the distance between the two electrodes was approximately 550 microm. Resistance of the electrodes had an average of 1.4 Omega with a standard deviation of +/-0.4 Omega. The surface of nitrocellulose membrane was modified by glutaraldehyde to immobilize streptavidin. Biotinylated anti-mouse IgG was conjugated with polyaniline-coated magnetic nanoparticles. Formation of polyaniline-coated magnetic nanoparticles was confirmed by a transmission electron microscope image. The polyaniline was used as an electric signal transducer for the monitoring of the biospecific binding event. An electrical response induced by the streptavidin-biotin interaction was measured by pulse mode measurement. This measurement method reduced the resistance caused by interfacial capacitance. Dose-dependent resistance changes were also successfully analyzed by the pulse mode polymeric wire biosensor. Results showed that the pulse mode measurement technique enhanced the performance of the polyaniline-based polymeric wire biosensor by reducing the interfacial effects. This approach could be helpful in samples with high interfering background materials, such as food and clinical specimens.     

Surface artery volume pulse wave measurement - verification of a new method

The aim of this paper is to prove the possible reproducibility of measurement with a new developed device for artery elasticity monitoring and determining the standard of major pulse wave parameters. As a measurement sensor, a conic probe with thin convex membrane was used. This technique allows setting an arbitrary pressure to a measured surface artery. We measured pulse waves on the radial arteries of 108 individuals. We expected similar features in arterial wall elasticity. We concentrated primarily on the amount of subcutaneous fat. For the measured waves we evaluated five following pulse wave parameters: relative crest time, elasticity index, dicrotic wave attenuation, dicrotic wave time and interwave distance. There were no significant differences in measured pulse wave parameters among the tested groups of subjects.     

MQ-HCN-based pulse sequences for the measurement of 13C1′-1H1′, 13C1′-15N, 1H1′-15N, 13C1′-13C2′, 1H1′-13C2′, 13C6/8-1H6/8, 13C6/8-15N, 1H6/8-15N, 13C6-13C5, 1H6-13C5 dipolar couplings in 13C, 15N-labeled DNA (and RNA)

A suite of multiple quantum (MQ) HCN-based pulse sequences has been developed for the purpose of collecting dipolar coupling data in labeled nucleic acids. All the pulse sequences are based on the robust MQ-HCN experiment which has been utilized for assignment purposes in labeled nucleic acids for a number of years and provides much-needed resolution for the dipolar coupling measurements. We have attempted to collect multiple couplings centered on the 13C1' and 13C6/8 positions. Six pulse sequences are described, one each for measurement of one-bond 13C1'-1H1' and 13C6/8-1H6/8 couplings, one for measurement of one-bond 13C1'-15N and two-bond 1H1'-15N couplings, one for measurement of one-bond 13C6/8-15N and two-bond 1H6/8-15N couplings, one for measurement of one-bond 13C1'- 13C2' and two-bond 1H1'-13C2' couplings, and one for measurement of one-bond 13C6-13C5 and two-bond 1H6-13C5 couplings in the bases of C and T. These sequences are demonstrated for a labeled 18 bp DNA duplex in a 47 kDa ternary complex of DNA, CBFbeta, and the CBFalpha Runt domain, thus clearly demonstrating the robustness of the pulse sequences even for a very large complex.     

Assessment of pulse rate variability by the method of pulse frequency demodulation

Background  

Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave signal and its usefulness for assessing pulse rate variability (PRV).     

用细胞色素C法检测非真空电子束辐射的间接作用

本文提出了一种检测非真空电束辐射的间接作用的一种方法,根据氧化型和还原型的细胞色素Ｃ的吸收光谱不同,从而测量非真空电子束作用对应的辐射分解的自由基总量。     

The role of the main photophase on dark-time measurement used for diapause determination in the Indian meal moth, Plodia interpunctella

Abstract.  The Indian meal moth Plodia interpunctella Hubner (Lepidoptera: Pyralidae) measures night length and enters diapause as a last-instar larva. To examine the role of photophase on dark-time measurement, the main LD 7 : 17 h photoperiod is disrupted by various lengths of darkness at 25 °C. When the light phase is not disrupted, the incidence of diapause is 76%. As the dark pulse disrupting a 7-h photophase becomes longer, the incidence of diapause decreases. To detect the dynamic kinetics of the time-measuring process, the main scotophase of 17 h is scanned by a 2-h light pulse. When the dark pulse in a 7-h photophase is fixed at 1 h after dawn and its duration is varied systematically from 1 to 3 h, or when the end of the dark pulse is fixed at 1 h before dusk, diapause is prevented completely by a 2-h light pulse inserted in the middle of 17-h darkness. These results are compared with those of a single night interruption of a 17-h scotophase with a 2-h light pulse but with an intact 7-h photophase. The disruption of a 7-h photophase by a dark pulse shifts the descending and ascending slopes of the response curve to some extent toward dawn and dusk, respectively, indicating that the dark pulse tends to shorten the critical length of dark time for diapause induction. When the main photophase (7 h) is interrupted by a 1-h dark pulse at 3–4 h after dawn, the 2-h scanning light pulse in the main scotophase (17 h) appears to act effectively as a dusk signal in the early scotophase. However, those in the mid- and late scotophase do not define the critical night length from dusk as sharply as for the critical night length from a 2-h light pulse to dawn. The results indicate the importance of photophase in the dark-time measurement.     

Short-pulse pump-and-probe technique for airborne laser assessment of Photosystem II photochemical characteristics

The development of a technique for laser measurement of fPhotosystem II (PS II) photochemical characteristics of phytoplankton and terrestrial vegetation from an airborne platform is described. Results of theoretical analysis and experimental study of pump-and-probe measurement of the PS II functional absorption cross-section and photochemical quantum yield are presented. The use of 10 ns probe pulses of PS II sub-saturating intensity provides a significant, up to 150-fold, increase in the fluorescence signal compared to conventional `weak-probe' protocol. Little effect on the fluorescence yield from the probe-induced closure of PS II reaction centers is expected over the short pulse duration, and thus a relatively intense probe pulse can be used. On the other hand, a correction must be made for the probe-induced carotenoid triplet quenching and singlet-singlet annihilation. A Stern-Volmer model developed for this correction assumes a linear dependence of the quenching rate on the laser pulse fluence, which was experimentally validated. The PS II saturating pump pulse fluence (532 nm excitation) was found to be 10 and 40 μmol quanta m⁻² for phytoplankton samples and leaves of higher plants, respectively. Thirty μs was determined as the optimal delay in the pump-probe pair. Our results indicate that the short-pulse pump-and-probe measurement of PS II photochemical characteristics can be implemented from an airborne platform using existing laser and LIDAR technologies. This revised version was published online in June 2006 with corrections to the Cover Date.     

On-line Estimation of the Rate of Sap Flow in Plant Stems Using Stationary Thermal Response Data

The heat pulse method for the measurement of the rate of sapflow in plants suffers from two drawbacks, viz. the discontinuousnature of the measurements and the lack of a precise mathematicalformulation of the heat fluxes. To overcome these drawbacksa random noise heat signal has been used as an input and twosensor pairs have been used for the measurement. A model isgiven that employs the signal from one sensor pair as inputand the signal from the second pair as output of a heat transportsystem. Thus the adverse effects of radial heat conduction havebeen eliminated. Simulation models with the rate of sap flowas one of the parameters have been fitted to the stationaryresponse data with an on-line parameter optimization algorithm.The method has been validated in applications to artificialdata and to real data obtained from a plastic tube and fromtomato plants. Key words: Sap flow, Heat pulse method, Continuous measurement     

Evaluation of a new tail-cuff method for blood pressure measurements in rats with special reference to the effects of ambient temperature

We evaluated a recently developed tail-cuff apparatus for the indirect blood pressure measurement in rats with special reference to the effects of ambient temperature. For this purpose, we designed two preparations 1) an intact preparation to determine the effect of ambient temperature on blood pressure measurements and 2) an anesthetized and catheterized preparation for comparison of the values of blood pressure obtained by the indirect and by the direct method. This apparatus also required enough pulse volume oscillations to measure the accurate value of blood pressure. Sufficient pulse volume oscillations were obtained within 20 min at 30 and 40 degrees C. At 40 degrees C, the values of blood pressure, pulse rate and rectal temperature were significantly higher than those at 30 degrees C. Correlation between blood pressure and rectal temperature was significant, and blood pressure increased with rectal temperature dependently. The values of the indirect measurement were close to the values measured directly, and these correlations were highly significant. Thus, we showed the effects of temperature for indirect blood pressure measurement. This tail-cuff apparatus could measure the accurate value of indirect blood pressure without thermal stress at 30 degrees C.     

Measurement of mean arterial pressure in rats by a tail-cuff method with sensitive photoelectric sensors

We evaluated a recently developed tail-cuff apparatus containing sensitive photoelectric sensors in the measurement of arterial pressure in rats. A total of 48 male Wistar rats were used in the study. The indirect mean arterial pressure (MPi) was determined from the cuff pressure when the pulse volume oscillations were maximal. To create sufficiently large pulse volume oscillations, we heated the rats for about 12 minutes at 38 degrees C prior to recording the pressure. The heating increased the mean arterial pressure by an average of 4 +/- 2 mmHg, as indicated by direct measurement of pressure. Three different sizes of cuffs were tested, with the result that the indirect measurements were nearly identical to those obtained directly when an appropriate cuff size was selected. The MPi was well correlated with the direct measurement of mean arterial pressure before (r = 0.918, p less than 0.001) and during (r = 0.903, p less than 0.001) elevation of arterial pressure via norepinephrine infusion. These results indicate that the MPi determined at maximum pulse volume oscillations coincides fairly well with the true mean arterial pressure.     

Quantitative analysis of the hemoglobin oxygenation state of rat brain in vivo by picosecond time-resolved spectrophotometry

Through the use of a picosecond laser pulse of near-infrared light at 1,064 nm, the temporal profile of the transmitted light through the anesthetized rat head has been investigated. The light intensity at a certain time after the input pulse was exponentially attenuated by the hemoglobin concentration with hematocrit values from 1.5 to 50%, although the transmitted pulse broadened markedly due to scattering by the cerebral tissue. The optical pathlength, which is required for quantitation of the absolute absorbance change, was directly determined, by the time of flight measurement of the light pulses, as the product of the velocity of light in tissue and time. The mean concentration of hemoglobin in the brain could be determined quantitatively by the use of this pathlength. The oxygen saturation of venous blood determined by our time of flight measurement was very close to that in the internal jugular vein determined directly with a gas analyzer. Thus, the picosecond laser technique is useful for quantifying the blood oxygenation in tissues.     

Measurement of fast dynamic intracellular pH in Saccharomyces cerevisiae using benzoic acid pulse

pH affects many processes on cell metabolism, such as enzyme kinetics. To enhance the understanding of the living cells, it is therefore indispensable to have a method to monitor the pH in living cells. To accomplish this, a dynamic intracellular pH measurement method applying low concentration benzoic acid pulse was developed. The method was thoroughly validated and successfully implemented for measuring fast dynamic intracellular pH of Saccharomyces cerevisiae in response to a glucose pulse perturbation performed in the BioSCOPE set-up. Fast drop in intracellular pH followed by partial alkalinization was observed following the pulse. The low concentration benzoic acid pulse which was implemented in the method avoids the undesirable effects that may be introduced by benzoic acid to cell metabolism.     

用新的计量方法研究黑腹果蝇的求爱歌

对雄果蝇求爱脉冲歌的研究已有多年的历史,但对脉冲间隔的计量方法并不方便。本文介绍我们采用微机终端计时新技术,自动对脉冲进行计数,可在范围更为广泛的数据信息内,对果蝇脉冲歌进行测量统计,对ipi分布中纵数与平均值的关系提出我们的看法,并首次对ipf及npb的分布进行了研究。     

Retinal pulse wave velocity measurement using spectral‐domain optical coherence tomography

The human eyes provide a natural window for noninvasive measurement of the pulse wave velocity (PWV) of small arteries. By measuring the retinal PWV, the stiffness of small arteries can be assessed, which may better detect early vascular diseases. Therefore, retinal PWV measurement has attracted increasing attention. In this study, a jump‐scanning method was proposed for noninvasive measurement of retinal PWV using spectral‐domain optical coherence tomography (SD‐OCT). The jump‐scanning method uses the phase‐resolved Doppler OCT to obtain the pulse shapes. To realize PWV measurement, the jump‐scanning method extracts the transit time of the pulse wave from an original OCT scanning site to another through a transient jump. The measured retinal arterial PWV of a young human subject with normal blood pressure was in the order of 20 to 30 mm/s, which was consistent with previous studies. As a comparison, PWV of 50 mm/s was measured for a young human subject with prehypertension, which was in accordance with the finding of strong association between retinal PWV and blood pressure. In summary, it is believed the proposed jump‐scanning method could benefit the research and diagnosis of vascular diseases through the window of human eyes.      

Interacting effects of photophase and scotophase on the diapause response of the Indian meal moth, Plodia interpunctella

The diapause-programming response to photoperiod in Plodia interpunctella was analyzed by exposing larvae to various 24-h and non-24-h regimes of light and darkness. The response to 24-h regimes indicated three photoperiodic parameters—a critical scotophase, a minimal photophase, and a minimal scotophase for a full expression of the response. The critical response was based on dark-time measurement, because disruption of the scotophase abolished the response and the diapause incidence varied as a function of scotophase in non-24-h regimes. The critical scotophase varied with the duration of the preceding photophase. Prevention of diapause by single or double-night interruptions of long scotophases could be explained by resetting of the dark-time measurement. The effect of a light pulse was modified by the quantitative interaction of light and dark reactions. The sensitivity to resetting by a light pulse seemed to be decreased in the early scotophase with an increasing duration of the preceding light period. Therefore, the significance of light in the photoperiodic response was something more than delimiting scotophase for the time measurement.     

An “hourglass-like” feature in the photoperiodic time measurement in Diatraea grandiosella (Pyralidae)

Photoperiodic time measurement of Diatraea grandiosella, a Pyralid moth, was investigated for its role in the determination of diapause by using various night-interruption protocols. The photoperiodic-response curve showed a temperature dependence under short days, whereas at long days it was stable in the range between 20 and 30°C. A light pulse averted diapause most effectively when it was placed 6 h after lights-off. Earlier pulses were less effective but gradually increased in effectiveness as the time of the pulse approached the critical time, i.e. 6 h after lights-off. A strong conversion in response appeared as the pulse passed the critical time. The same response pattern was observed both in diapause induction and termination. The species required a long light pulse to avert diapause completely, even if the light pulse was placed during the critical time; 45 min was required to reverse diapause in 50% of the individuals. The most crucial event for photoperiodic time measurement in this species was whether a night phase 6–7.5 h after lights-off was illuminated or not. This hourglass-like feature was also shown in more complex night-interruption protocols with 2–3 light pulses. A possible relation of this phenomenon to the cricadian pacemaker was sought. The Dual System Theory failed to account for most of the features for the photoperiodic time measurements of D. grandiosella found in this study.