HOME MEASUREMENT OF BLOOD PRESSURE: PRESENT PROBLEMS AND PERSPECTIVE IMPROVEMENTS

The most frequently performed health test is the measurement of blood pressure. Popularity of home measurement increased substantially with the introduction of inexpensive automatic instruments to the market. Accurate measurement of blood pressure is important for diagnosis and management of hypertension. Inaccuracies of measurement with automatic oscillometric instruments are caused by wrong size cuff and by errors in algorithmic measurement. The authors developed several perspective improvements in the measurement of systolic pressure. An experimental system for acquisition and processing of arterial pressure pulses facilitated the development of these methods. More accurate measurement of the systolic pressure was achieved with a dual-cuff method. A new method of wrist-cuff pulse analysis facilitated estimation of hemodynamics. Estimation of hemodynamics simultaneously with measurement of blood pressure provides the physician with more complete picture of the type of hypertension and it facilitates better diagnosis and management. An inexpensive commercial instrument based on the methods developed by the authors could be used by the patient in home care

CARDIOPULMONARY EXERCISE TESTING FOR VO2MAX DETERMINING IN SUBJECTS OF DIFFERENT PHYSICAL ACTIVITY

Cardiopulmonary exercise testing (CPET) provides assessment of the integrative exercise responses involving the pulmonary, cardiovascular, haematopoietic, neuropsychological, and skeletal muscle systems, which are not adequately reflected through the measurement of individual organ system function. This non-invasive, dynamic physiological overview permits the evaluation of both submaximal and peak exercise responses, providing the doctor with relevant information for clinical decision making. CPET is increasingly being used in a wide spectrum of clinical applications for the evaluation of undiagnosed exercise intolerance and for the objective determination of functional capacity and impairment. Its use in patient management is increasing with the understanding that resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity and that overall health status correlates better with exercise tolerance than with resting measurements. CPET involves measurements of respiratory oxygen uptake, carbon dioxide expenditure and pulmonary ventilation during a step-vice increased physical workload up to the maximum (or symptom-limited level in patients) on ergometer. In this paper the principle of CPET is described and results for VO2max and VO2max/kg of almost 3000 measurements in subjects of different physical activity are presented. These values characterizing cardiorespiratory capacity of the subjects were compared to the values of maximal performance achieved during stress test on bicycle ergometer (Wmax and Wmax/kg) and regression equations for VO2max – Wmax and VO2max/kg – Wmax/kg were calculated

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

New Mixer Used in Direct Frequency Synthesizer

Frequency synthesizers are an essential part of any modern transceiver system. They generate clock and oscillator signals needed for up and down conversion. Today’s communication standards demand both high frequency accuracy and fast frequency settling. The fine frequency resolution, low spurious signals, accuracy and stability are most important for these devices. In this paper, the new frequency synthesizer architecture based on direct synthesis and coincidence mixer is presented. The simulation results are also shown

Sinusoidal and Relaxation Wide Range Voltage Controlled Oscillators

This paper presents a sinusoidal Wien-bridge and square wave wide range voltage controlled oscillators. The square wave oscillator is based on relaxation (Schmitt trigger) topology. All described oscillators have potential use in different applications, e.g. phase locked loops, modulation and detection. The frequency changing is based on optically coupled resistor with 100 dB dynamic range. The oscillators were constructed and measured. The new method for amplitude control for quadrature oscillator is also described

Solution of the System Structure Reconstruction Problem Based on Generalization of Tellegen's Principle

An extraordinary generality, conceptual simplicity and practical usefulness of the Tellegen's theorem is well known in the field of electrical engineering [1]. It is one of few general theoretical results that apply in non-linear and time-varying situations, too. For standard linear electrical network models with constant parameters many classical results of electrical circuits theory can be derived as direct consequences of it. In the paper a more general class of abstract strictly causal system representations is addressed. A new problem, that of the abstract state space system representation structure reconstruc-tion has been formulated in [3], and partially solved in [3] and [4]. In this paper a new approach based on a generalized form of the classical Tellegen's principle, providing an equivalence class of physically as well as mathematically correct solutions is developed and some well-known, as well as new results are shown to be straightforward consequences of the derived struc-ture. Some connections of dissipativity, conservativity, state and parameter minimality, instability and chaos with system representation structures are investigated from this point of view. Analytical results are illustrated by a number of typical examples and visualized by simulations