Purification of Masked Temperature data from Humans: Some Preliminary Observations on a Comparison of the use of an Activity Diary, Wrist Actimetry, and Heart Rate Monitoring

Fourteen ambulatory subjects, varying in their amount of habitual physical activity, were studied for 24h during a total of 25 “typical” days. Rectal temperature was recorded every 6 minutes, an activity diary was filled in every half hour, and wrist activity and heart rate were monitored every minute. Actimetry and heart rate data generally showed close parallelism with each other and with the masking effects on body temperature. Psychological stressors such as public speaking produced a greater effect on heart rate and body temperature than on wrist movement, while typing produced high values for wrist movement, but affected heart rate and temperature much less. When data for the circadian rhythm of body temperature were purified, the diary, actimetry, and measurement of heart rate were all useful in reducing masking effects, but the present evidence indicates that heart rate can be more successful than actimetry-as judged by the closeness of the purified data to a sinusoid. This superiority of heart rate monitoring over wrist activity as a method of purification might be because core temperature can be increased by stressor-induced thermogenesis, as well as by physical activity, and because wrist movement can, with some activities, give an inaccurate estimate of the factors that contribute to whole-body thermogenesis.     

Understanding autonomic sympathovagal balance from short-term heart rate variations. Are we analyzing noise?

Heart rate variations reflect the output of the complex control of the heart mediated by the autonomic nervous system. Because of that, they also encode different types of information, namely the efferent outflow of reflex mechanisms involved in the beat-to-beat control of cardiac function, the efferent activity of neurohumoral elements involved in the control of other cardiovascular parameters and random noise resulting from the hysteresis of the different controllers. The degree to which power spectrum estimation methods will uncover the periodic component of heart rate variations is in direct relation with the status of the system under study. Although the utility of spectral methods is now established in mammalian research, very little is known on the utility of these techniques in non-mammalian cardiovascular research. This review covers this space by discussing the physiological significance of heart rate variations in non-mammalian vertebrates. A detailed account of the different steps of the technique, its limitations and the ways to overcome these problems are also presented. These are: the recording of the cardiac event signal, the detection and digital processing methods, the satisfaction of stationarity conditions, the problem of spectral leakage and the different methods to estimate the power spectrum.     

Centrale de mesure ambulatoire biomédicale sur PSoC

Improvement in quality and efficiency of health and medicine, at home and in hospital, has become of paramount importance. The solution to this problem would require the continuous monitoring of several key patient parameters, including the assessment of autonomic nervous system (ANS) activity using non-invasive sensors, providing information for emotional, sensorial, cognitive and physiological analysis of the patient. Recent advances in embedded systems, microelectronics, sensors and wireless networking enable the design of wearable systems capable of such advanced health monitoring. The subject of this article is an ambulatory system comprising of a small wrist device connected to several sensors for the detection of the autonomic nervous system activity. It affords monitoring of skin resistance, skin temperature and heart activity. It is also capable of recording the data on a removable media or sending it to computer via a wireless communication. The wrist device is based on a programmable system-on-chip (PSoC) from Cypress.     

Chronobiologically interpreted ambulatory blood pressure monitoring: past,present, and future

Research at the Halberg Chronobiology Center focused to a large extent on the monitoring of blood pressure (BP) and heart rate (HR). Self-measurements and later ambulatory BP monitoring yielded new knowledge of interest to basic science and clinical practice. After a brief review of BP measurement, we outline developments in methods of data analysis that paralleled technological advances in the measurement of BP. We review work done in cooperation with colleagues worldwide to illustrate how a chronobiological approach led to the mapping of spontaneous circadian and other rhythms for the derivation of refined reference values and to the assessment of response rhythms underlying chronotherapy. BIOCOS members work in different fields, spanning from cardiology and nutrition to obesity, diabetes, exercise physiology and rehabilitation, but all strive for “pre-habilitation”. The early recognition of increased risk can prompt the timely institution of prophylactic intervention. As technology continues to improve, studies on groups are complemented by longitudinal self-surveillance for health maintenance. Longitudinal records serve for the investigation of environmental influences on human physiology, the topic of chronomics. As current advances in technology and wireless communication will likely impact the future of healthcare, chronobiological methods and concepts should be an integral part of this seachange.     

Direct biologically based biosensing of dynamic physiological function

Dynamic regulation of biological systems requires real-time assessment of relevant physiological needs. Biosensors, which transduce biological actions or reactions into signals amenable to processing, are well suited for such monitoring. Typically, in vivo biosensors approximate physiological function via the measurement of surrogate signals. The alternative approach presented here would be to use biologically based biosensors for the direct measurement of physiological activity via functional integration of relevant governing inputs. We show that an implanted excitable-tissue biosensor (excitable cardiac tissue) can be used as a real-time, integrated bioprocessor to analyze the complex inputs regulating a dynamic physiological variable (heart rate). This approach offers the potential for long-term biologically tuned quantification of endogenous physiological function.     

The cardiac hormonal system as a link in hemodynamic regulation and water-salt homeostasis

Classic and modern data on natriuretic peptide hormones that are synthesized in cardiac atria and participate in hemodynamic and water-salt balance regulation are summarized in this paper. Cumulated data on polypeptide variety, their structure, intracellular syntheses, physiological effects and concentration alterations during model experiments and cardiovascular pathology are presented. Unsolved problems including methods of plasma peptides concentration measurements, their role in heart failure development, and their clinical significance are discussed.     

Comparative accuracy of two new electronic devices for the noninvasive determination of blood pressure

Recent developments in behavioral approaches to cardiovascular disease have called for physiological monitoring devices that reduce experimenter bias, are easy to operate, can be used ambulatorily, and/or provide ongoing, automated monitoring of pertinent cardiovascular functions--i.e., blood pressure and heart rate. Neither the invasive monitoring (via catheterization) nor the standard auscultatory method of blood pressure determination, however, has these characteristics. In the present study, two new methods/devices--(1) a low-weight, low-cost, battery-operated sphygmomanometer (SM), and (2) a more expensive automated electronic SM with electrical pump-are compared with each other and with the more common auscultatory method and a standard mercury SM. Both new devices were also compared with a standard pulse count. Data were derived from 10 readings of 10 healthy subjects each across the three possible comparisons, thus totaling N = 30. Correlation coefficients and average differences were computed and indicated high intercorrelations (between r = .89 and r = .99) between each pairing of the new electronic devices and the mercury SM. Intercorrelations of blood pressure determination with the two new electronic devices, however, were only moderate. Potential reasons for the variability are discussed, and guidelines for the optimal use of the new, easy-to-operate electronic devices are presented.     

心肌重塑的研究进展

心肌重塑是心脏在一些生理的或病理的刺激作用下,心肌细胞和心肌细胞外基质在细胞结构、功能、数量及遗传表型方面出现的明显的变化即心脏的大小、形状和功能的变化。心肌细胞和心肌细胞外基质从根本上参与了心肌重塑的过程。目前,对于影响心肌重塑的因素及作用机制的研究主要集中在血流动力学和神经体液方面。近年来,对于不良心肌重塑的逆转干预,包括药理干预、运动干预,一直持续不断,研究的不断深入给相关疾病的改善、治疗带了新的进展和希望。心肌重塑可能是生理性的或病理性的,生理性的重塑是心肌的适应性代偿性变化,而病理性的重塑是心肌的不适应变化,对身体产生危害性。本文主要对病理性心肌重塑的主要组成部分,影响心肌重塑的因素及相关机制,改善不良心肌重塑的有效干预做一个综述,并提出展望。     

Biocybernetic studies on reflectory heart modification in the rabbit]

In rabbits the depressor nerves and cardiac vagal branches were stimulated. Their actions on heart rate, atrio-ventricular conduction time, myocardial action potential and mean central blood pressure were recorded. The frequency-effect characteristics of the chronotropic, dromotropic and electrotropic actions on the heart, resulting from afferent and efferent nerve stimulation, are compared. The participation of each of the depressor nerves in their total effects on heart rate and blood pressure is studied. Time courses of heart rate and blood pressure decrease by afferent and efferent nerve stimulation with sinusoidally modulated pulse rates are presented. The results are discussed with respect to the different dynamics of blood pressure and heart rate control. It is concluded that at least two mechanisms are involved in blood pressure control by the depressor nerves: 1. Decrease of vascular resistance by lowering the sympathetic tone. 2. Decrease of heart rate by enhancing the cardiac vagal activity. It is suggested that the parasympathetic control unit compensates rapid disturbances, whereas the slow-acting sympathetic vascular mechanism exerts a long-time pressure control of high efficiency.     

Comparative accuracy of two new electronic devices for the noninvasive determination of blood pressure

Recent developments in behavioral approaches to cardiovascular disease have called for physiological monitoring devices that reduce experimenter bias, are easy to operate, can be used ambulatorily, and/or provide ongoing, automated monitoring of pertinent cardiovascular functions—i.e., blood pressure and heart rate. Neither the invasive monitoring (via catheterization) nor the standard auscultatory method of blood pressure determination, however, has these characteristics. In the present study, two new methods/devices — (1) a low-weight, low-cost, battery-operated sphygmomanometer (SM), and (2) a more expensive automated electronic SM with electrical pump — are compared with each other and with the more common auscultatory method and a standard mercury SM. Both new devices were also compared with a standard pulse count. Data were derived from 10 readings of 10 healthy subjects each across the three possible comparisons, thus totalingN=30. Correlation coefficients and average differences were computed and indicated high intercorrelations (betweenr=.89 andr=.99) between each pairing of the new electronic devices and the mercury SM. Intercorrelations of blood pressure determination with the two new electronic devices, however, were only moderate. Potential reasons for the variability are discussed, and guidelines for the optimal use of the new, easy-to-operate electronic devices are presented.     

基于心脏电生理模型的心律失常机制研究进展

揭示发病机制是心律失常诊断、治疗、药物研发和设备设计的关键.整合当前在心脏分子生物学、生物化学、生理学及解剖学方面的最新成果,构建从离子通道、心肌细胞、心肌纤维、心肌组织、心脏器官到躯体各个层次的多尺度多模态心脏电生理模型,用于系统研究微观局部变化发生、发展、转化为宏观心律失常表现的过程,将彻底改变传统从基因突变、蛋白质表达、细胞电生理、临床表现单独研究心律失常的方式,实现微观与宏观研究的统一,使心脏电生理模型成为系统研究心律失常发病机制的有力手段.本文综述了心脏电生理模型的构建方法和研究进展,讨论了多尺度心脏电生理模型在揭示心律失常机制研究中的作用和地位,给出了基于心脏电生理模型心律失常研究的挑战和重要发展方向.     

Laser assessment of leaflet closing motion in prosthetic heart valves

The dynamics of leaflet motion in heart valve prostheses (HVP), and in particular the closing velocity, is believed to be related to the valve sound and possibly to the phenomenon of valve cavitation. This paper describes a non-intrusive laser sweeping technique enabling the study of leaflet motion. The principle of measurement and the equipment involved are presented, together with the results of two commerially available, 29 mm bileaflet mitral valves, a St. Jude Medical, and an Edwards Duromedic valve. Experiments were carried out in a pulsatile mock flow testing loop designed to mimic physiological pressure waveforms and ventricular contraction. Measurements of heart rate were made in the range 70–120 beats min⁻¹, with a ventricular pressure slope range of 1800–5600 mm Hgs⁻¹ and a cardiac output range of 5.0–7.5 litres min⁻¹. Motion analysis of the measured data focuses on the velocity of the leaflet immediately before closure.     

Complexity and characteristic frequency studies in ECG signals of mice based on multiple scale factors

Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency. We developed a technique to measure the multifractal characteristic parameter intimately associated with physiological activities through a frequency scale factor. This parameter is highly sensitive to physiological and pathological status. Mice received various drugs to imitate different physiological and pathological conditions, and the distributions of mass exponent spectrum curvature with scale factors from the electrocardiogram (ECG) signals of healthy and drug injected mice were determined. Next, we determined the characteristic frequency scope in which the signal was of the highest complexity and most sensitive to impaired cardiac function, and examined the relationships between heart rate, heartbeat dynamic complexity, and sensitive frequency scope of the ECG signal. We found that all animals exhibited a scale factor range in which the absolute magnitudes of ECG mass exponent spectrum curvature achieve the maximum, and this range (or frequency scope) is not changed with calculated data points or maximal coarse-grained scale factor. Further, the heart rate of mice was not necessarily associated with the nonlinear complexity of cardiac dynamics, but closely related to the most sensitive ECG frequency scope determined by characterization of this complex dynamic features for certain heartbeat conditions. Finally, we found that the health status of the hearts of mice was directly related to the heartbeat dynamic complexity, both of which were positively correlated within the scale factor around the extremum region of the multifractal parameter. With increasing heart rate, the sensitive frequency scope increased to a relatively high location. In conclusion, these data provide important theoretical and practical data for the early diagnosis of cardiac disorders.     

心脏特异性高度表达的抗凋亡蛋白——ARC

与凋亡(apoptosis)相关的许多心脏疾病如心肌梗死、心肌病及心衰等严重威胁着人类的健康和生命.寻找有效手段防治这些心脏病是当前医学研究的热点.ARC(带有caspase富集功能域的凋亡抑制因子)是新近发现的唯一在心脏大量且特异表达的抗凋亡蛋白,其全称是带有caspase富集功能域的凋亡抑制因子.ARC可被持续性磷酸化并参与阻断凋亡发生途径的多个层面.因此,ARC是一种强大的抗心肌凋亡蛋白.     

Perfused heart studies to investigate lipid metabolism

The isolated perfused heart preparation is an invaluable model for investigating metabolism in a variety of physiological and pathological states. It avoids confounding systemic factors (e.g. endocrine, metabolic and work load changes) and permits simultaneous measurement of mechanical function. The ability to measure arteriovenous concentration differences across the myocardium and the coronary flow rate, together with the use of radiolabelled substrates, permits assessment of substrate assimilation and disposition of most potential energetic substrates. In the case of lipids, metabolism of non-esterified fatty acids has been extensively investigated in the perfused rat heart, but fatty acids may also be derived from circulating triacylglycerols (TAG) in lipoproteins [chylomicrons, very-low-density-lipoprotein (VLDL)]. TAG requires initial hydrolysis by the endothelial enzyme lipoprotein lipase and hence an intact heart preparation is vital to maintain tissue structural integrity. Chylomicron-TAG utilization and fate (oxidation, tissue-lipid deposition) in isolated working hearts has been studied using chylomicrons obtained from thoracic-duct catheters. However, lack of availability of sufficient quantities of VLDL has hindered examination of their cardiac utilization; the recent development of a technique to produce large quantities of radio-labelled rat VLDL has facilitated these studies and established that VLDL-TAG is an important metabolic substrate for working heart. Results relating to myocardial utilization of VLDL-TAG under varying physiological (lactation) and pathological (endotoxinaemia) conditions will be presented. The putative role of VLDL as a regulator of cardiac lipid metabolism will also be discussed.     

Genetic deficiency in tissue kallikrein activity in mouse and man: effect on arteries, heart and kidney

Tissue kallikrein (KLK1) is a kinin-forming serine protease synthesized in many organs including arteries and kidney. Study of the physiological role of KLK1 has benefited from the availability of mouse and human genetic models of KLK1 deficiency, through engineering of KLK1 mouse mutants and discovery of a major polymorphism in the human KLK1 gene that induces a loss of enzyme activity. Studies in KLK1-deficient mice and human subjects partially deficient in KLK1 have documented its critical role in arterial function in both species. KLK1 is also involved in the control of ionic transport in the renal tubule, an action that may not be kinin-mediated. Studies of experimental diseases in KLK1-deficient mice have revealed cardio- and nephro-protective effects of KLK1 and kinins in acute cardiac ischemia, post-ischemic heart failure, and diabetes. Potential clinical and therapeutic developments are discussed.     

Right ventricular function and failure: a review.

The importance of right ventricular (RV) function in maintaining global cardiac performance is the focus of this discussion. The physiological determinants of normal right ventricular function will be discussed, with particular emphasis on the afterload and contractility characteristics of the right ventricle. Numerous clinical conditions have been shown to affect RV performance. These conditions include positive-pressure ventilation, ischemia, pulmonary hypertension, and cardiac surgery. Present methods for the perioperative evaluation of RV function include angiography, radionuclide techniques, thermodilution techniques, echocardiography, and magnetic resonance imaging. Traditional modalities for the treatment of RV dysfunction consist of pharmacological interventions (i.e., vasodilators and inotropes) and/or mechanical assist devices. Newer pharmacological strategies for the treatment of RV failure and associated pulmonary hypertension include the phosphodiesterase fraction III inhibitors and the prostaglandins, specifically PGE1. In summary, the accurate evaluation of perioperative RV performance combined with new treatment options will ensure maximal preservation of RV performance.     

Changes in Heart Rate Associated with Contest Outcome in Agonistic Encounters in Lobsters

Agonistic contests between lobsters housed together in a confined space progress through encounters of increasing intensity until a dominance relationship is established. Once this relationship is established, losing animals continually retreat from the advances of winners.These encounters are likely to consume much energy in both winning and losing animals. Therefore, one might expect involvement of many physiological systems before, during and after fights. Here, we report effects of agonistic encounters on cardiac frequency in winning and losing adult lobsters involved in dyadic interactions.The results show that: (i) small but significant increases in heart rate are observed upon chemical detection of a conspecific; (ii) during agonistic interactions, further increases in heart rate are seen; and (iii) ultimate winners exhibit greater increases in heart rate lasting longer periods of time compared to ultimate losers. Heart rate in winners remains elevated for at least 15 min after the contests have ended and animals have been returned to their home tanks. Reduced effects are seen in second and third pairings between familiar opponents.The sustained changes in heart rate that we observe in winning lobsters may result from hormonal modulation of cardiac function related to the change in social status brought about by contest outcome.     

Quantitative ballistocardiography (Q-BCG) for measurement of cardiovascular dynamics

In the seventies of the past century ballistocardiography had been thought to be obsolete in cardiology for impossibility of objective calibration. In the present work the quantitative ballistocardiography (Q-BCG) for measurement of systolic force (F) and minute cardiac force (MF) in sitting subject was described. The new principle of piezoelectric transducer enabled to register the force caused by the heart and blood movement, which was not measured before. The calibration proved that the action of the force on the transducer was expressed quantitatively without the amplitude-, time-, and phase deformation. The close relationship of skeletal muscle force and F was proved. The F and MF changed under different physiological conditions (age, partial pressure of oxygen, body weight, skeletal muscle force). It was shown that the systolic force (F) and minute cardiac force (MF) are the physiological parameters neurohumorally regulated similarly as the heart rate or systolic volume.     

Motion energy as a control variable for adapting stimulation frequency

An activity sensing rate-responsive pacing system is presented which adaptively controls heart rate to adjust cardiac output in response to increased metabolic demand, and more optimally restore homeostasis of the intact cardiovascular system. The current use of ventricular demand and DDD universal pacing systems, although rate and multi-parameter and multi-function programmable, are fixed at these programmed settings. These devices are adequate for patients at rest or during moderate exertion, but are suboptimal for physically active patients whose physiology requires increased oxygen supply to meet an increased cardiac demand. In the past, these patients may have experienced fatigue or dyspnea out of proportion to their cardiovascular disease. The Ergos rate-adaptive single- and dual-chamber pacing system is a second generation pulse generator which is rate responsive to a patient's increased physiologic demand by sensing a motion signal which reflects increased work load and the need for a compensating increase in heart rate. Ergos offers increased assistance to patients with sinus bradycardia who may require the rate-responsiveness with the additional advantage of AV synchrony. Clinical results show the effectiveness of the presented sensor control by motion energy for rate adaptive pacing therapy.