Complexity analysis of electrocardiographic signals

Two types of electrocardiographic data series were investigated using appropriate tests based on a selection of semi-quantitative analysis algorithms. Distribution histograms, power spectra, auto-correlation functions, state-space portraits, Lyapunov exponents and wavelet transformations were applied to electrocardiograms of normal and stressed subjects. Statistical analysis using the Student's t-test revealed significant and non-significant alterations in stress-loaded cases compared to normal ones. Higher levels of adrenaline may account for a more complex dynamics (deterministic chaos) revealed in the stressed subjects.     

Cross inhibition models for the transmission of hormonal signals.

Implications of a model where the formation of two mediators interacting through cross inhibition is stimulated by the same hormone or by two specific hormones are analyzed at steady'state, first in the case where no co-operative processes are involved, secondly in the case where one of the inhibitory branches presents positive co-operativity characteristics. The possible occurrence of agonist concentration-mediators response curves with extrema of opposite type, multiple steady states, hysteresis and discontinuous transitions from one functional program to another is demonstrated. When steady-state hormonal levels fluctuate, it is shown that the cross inhibitory mediators may induce a strict temporal organization of the intracellular processes and result in both amplification and frequency multiplication of the fluctuations.     

Mutants in transmission of chemotactic signals from two independent receptors of E. coli.

We have characterized chemotactic mutants of E. coli that appear to be defective in a common linkage of two independent receptors to the central chemotactic components. The mutants do not respond to gradients of ribose or galactose and thus are called trg (taxis to ribose and galactose), after Ordal and Adler (1974b). These trg mutants are indistinguishable from their parent in tactic response to other attractants, swimming pattern, growth rates, and transport of ribose and galactose. The mutant cells contain the usual amounts of ribose and galactose receptors, and those proteins function normally in their other role, transport of their respective ligands. The mutations, generated by insertion of translocatable drug-resistance elements (transposons)8 are located near 31 min on the map of the E. coli chromosome, a locus far removed from the genes coding for the ribose and galactose receptors. Trg mutants do not resemble either specific receptor mutants or che mutants. The nature of the requirement for the trg product in the response to ribose and galactose is not defined, but evidence for interference of tactic signals from the ribose and galactose receptors (Strange and Koshland, 1976) supports the idea that the product functions directly in the transmission of tactic signals from the two receptors to the flagella.     

Long-distance of transmission of facial affect signals

This study examined the distance at which certain facial expression can transmit affect messages. A man and a woman assumed—facial expressions that were selected carefully to represent six affects. These expressions were shown in still photographs and in live portrayals to 49 observers who composed four groups which were 30, 35, 40, and 45 meters away from the stimuli. Photographs and live portrayals produced comparable results. Every observer was able to label the expressions accurately although accuracy declined as distance increased. Extrapolation from the data suggested that some messages may be sent far beyond the distances used in this study. These results raise important issues about the transmission of facial signals over distance and suggest that the face is a long-distance transmitter of affect signals.     

Some mathematical aspects of the diagnostic process. II: A mathematical model of electrocardiographic diagnosis

In a previous paper (Bartholomay, 1971), a general mathematical model of the medical diagnostic process was described. The present paper amounts to a relization of that process in terms of conventional 12-lead electrocardiographic diagnosis as enunciated by Dr. Harold D. Levine (1966) in the course of a collaborative study by Dr. Levine and the present author at the Peter Bent Brigham Hospital of the Harvard Medical School between 1963 and 1966. The main details of the cognitive component of that model are described in detail here. The model has been programmed onto a computer system consisting of an analog-digital converter and general purpose digital computer and amounts to a simulation of Dr. Levine’s electrocardiographic analysis procedure.     

Practical value of Frank's leads in electrocardiographic diagnosis of myocardial infarction

Authors' own modification of Frank's leads is discussed. Potentials from these leads are recorded simultaneously with routine ECG. Frank's leads are used to increase possibility to diagnose myocardial infarction. Proposed leads in x, y, z, axis of Frank system enable to differentiate pathological QS wave in chest V1-V3 leads between myocardial infarction of the anterior wall and detectable intraventricular potentials in patients with emphysema. A lack of physiologic Q wave in "z+"-lead always indicates anterior wall infarction. Pronounced Q wave of "infarctional" character in y-lead x-lead--in the lesions to the lateral wall. Pathologies present in the posterior wall infarction while from cal Q wave from "z+"-lead facilitates diagnosis of the posterior wall infarction.     

Issues involved in the transmission of chemical signals through the brain extracellular space

Two classes of substances exist within the extracellular space: energetic and informational. Examples of the former are glucose, dissolved oxygen and CO2 while the latter include excitatory amino acids, cathecholamines and opiates. The simple ions Na+ and Cl- are generally associated with energetic processes while extracellular K+ and Ca2+ tend to be informational in function. Local release of an informational substance brings about a concentration gradient that causes the substance to be dispersed in the extracellular space by diffusion. This process is modified relative to a free aqueous medium by the constraints of volume fraction, tortuosity and uptake. Volume fraction is defined simply as the fraction of a brain region that is extracellular. If a given quantity of substance is released into a region with a reduced volume fraction then the substance will reach a higher concentration than it would in a free medium. Tortuosity is related to the increase in the path length of the random walk of a diffusing particle due to the necessity to navigate around cellular obstructions. Tortuosity manifests itself as a decrease in the diffusion coefficient. Uptake represents the movement of a substance from the extracellular space to the intracellular. Since initially a concentration gradient exists in this direction and all membranes have some permeability some concentration-dependent uptake always occurs. In addition there exist specific carrier-mediated uptake processes for some substances such as amino acids or catecholamines. In some regions the dispersal process can be dominated by uptake rather than diffusion. While volume fraction, tortuosity and uptake have all been demonstrated by a technique based on the use of radiolabels and other methods, these classical techniques have limited spatial and temporal resolution. The advent of methods based on micro-injection of substances by iontophoresis or pressure and subsequent detection with ion-selective microelectrodes (ISMs) or voltammetric microsensors (VMs) has opened a new window onto the dynamic local behavior of the extracellular space. In the last decade our laboratory and others have studied the migration of the test substances tetramethylammonium, tetraethylammonium, AsF6- and alpha naphthalene sulfonate, the endogenous ions K+ and Ca2+, the epileptogenic agent penicillin and the neurotransmitter dopamine. These studies have been carried out on the cerebellum and some other regions in a variety of species that include rat, turtle, skate and an intervertebrate, the cuttlefish.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hi-Fi transmission of periodic signals amid cell-to-cell variability

Since information in intracellular calcium signaling is often frequency encoded, it is physiologically critical and experimentally useful to have reliable, convenient, and non-invasive methods to entrain it. Because of cell-to-cell variability, synchronization of intracellular signaling across a population of genetically identical cells can still be difficult to achieve. For intrinsically oscillatory signaling pathways, such as calcium, upon continuous stimulation, cell-to-cell variability is manifested as differences in intracellular response frequencies. Even with entrainment using periodic stimulation, cell-to-cell variability is manifested as differences in the fidelity with which extracellular inputs are converted into intracellular signals. Here we present a combined theoretical and experimental analysis that shows how to appropriately balance stimulation strength, duration, and rest intervals to achieve entrainment with high fidelity stimulation-to-response ratios for G-protein-coupled receptor-triggered intracellular calcium oscillations. We further demonstrate that stimulation parameters that give high fidelity entrainment are significantly altered upon changes in intracellular enzyme levels and cell surface receptor levels. Theoretical analysis suggests that, at key threshold values, even small changes in these protein concentrations or activities can result in precipitous changes in entrainment fidelity, with implications for pathophysiology.     

Rapid transmission of oxidative and nitrosative stress signals from roots to shoots in Arabidopsis.

Protein kinases play a central role in signal transduction pathways in eukaryotes. A highly conserved group of kinases, termed mitogen-activated-protein kinases (MAPKs) was shown to mediate many diverse stress responses. In plants, MAPKs were shown to function in resistance responses to many biotic and abiotic stresses. Here, we show that exposure of Arabidopsis roots to hydrogen peroxide or to nitric oxide resulted in rapid activation of protein kinases in the shoots that exhibited MAPK properties. The same pattern of kinases was induced by direct injection of these compounds into leaves, indicating accurate long-distance transmission of H2O2 and NO signals. These results are important for the understanding of redox signal transmission from the rhizosphere throughout the plant.     

On the transmission of signals in vertebrate retina in the presence and absence of impulses

The ability to transmit signals in the retina in the absence of impulses was tested by means of two agents (tetrodotoxin and procain) blocking the impulse transmission of stimuli. The slow potential (SP) and impulse discharge were recorded simultaneously from the optic nerve of the frog. Tetrodotoxin (0.5 µg/cm³) and procain (0.5–1%) introduced into the eye cup completely blocked impulses but had little effect on SP. Therefore, signals from the photoreceptors to the ganglionic cells can be transmitted in the absence of impulses. These data confirm also a conclusion drawn earlier that the SP originates as a result of electrotonic spread of the postsynaptic potentials (PSP) of ganglionic cells along the optic nerve. The agents blocking the impulse transmission of stimuli broke down the lateral inhibition between the "slow bipolars." Consequently, lateral inhibition spreads by means of the impulse mechanism in the transmission of signals. It is supposed that the interneurons participating in this spread are amacrine cells which possess the ability to generate impulses.Institute of Problems of Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 2, No. 5, pp. 536–543, September–October, 1970.     

Vibratory signals of the harlequin bug and their transmission through plants

Abstract. Males of the harlequin bug, Murgantia histrionica (Hahn), produce five different vibrational songs, whereas females produce one song. Songs differ from those of other stink bugs primarily in their species‐specific temporal characteristics. The broad band male courtship songs of M. histrionica are achieved by a combination of different frequency modulated and/or narrow band subunits, with several higher harmonic frequencies. Males rather than females initiate substrate‐borne vibrational communication, and the longer‐range calling songs found typically in other pentatomid species are lacking. Interindividual differences in song temporal and spectral characteristics are discussed. Transmission of vibrational songs through a cabbage head is more efficient along veins than along lamina. Attenuation of signals transmitted through veins is low and similar to that reported previously for plant stalks. On the leaf vein, distances between peak amplitude minima and maxima are different for the dominant and subdominant frequencies. At any distance from the vibration source, a different relationship between spectral peak amplitudes can be recorded. Resolution of these differences, together with velocity differences between signals recorded on the vein and lamina, may help small stink bugs to estimate distance and to locate each other on a plant.     

Connexin36 is essential for transmission of rod-mediated visual signals in the mammalian retina

To examine the functions of electrical synapses in the transmission of signals from rod photoreceptors to ganglion cells, we generated connexin36 knockout mice. Reporter expression indicated that connexin36 was present in multiple retinal neurons including rod photoreceptors, cone bipolar cells, and AII amacrine cells. Disruption of electrical synapses between adjacent AIIs and between AIIs and ON cone bipolars was demonstrated by intracellular injection of Neurobiotin. In addition, extracellular recording in the knockout revealed the complete elimination of rod-mediated, on-center responses at the ganglion cell level. These data represent direct proof that electrical synapses are critical for the propagation of rod signals across the mammalian retina, and they demonstrate the existence of multiple rod pathways, each of which is dependent on electrical synapses.     

Current diagnosis and treatment of cardiac arrhythmias of thyroid origin

Cardiac arrhythmias may often be of the thyroid origin. It is so-called thyroid-cardiac syndrome which may also be manifested by the circulatory failure and angina pectoris. The authors have been observed 54 cases of such arrhythmias; they have frequently been manifested by the paroxysmal tachycardia, extrasystolic beats, and paroxysmal or stable atrial fibrillation. Diagnosis of such arrhythmias may be difficult in case of the masked hyperthyroidism being its only clinical symptom. In order to establish a proper diagnosis the following tests of thyroid gland functioning have been carried out: TRH-TSH, scintigraphy and ultrasound examination of the thyroid gland. TRH-TSH test enables to detect disorders of hypophyseal-thyroidal regulation characteristic for both overt and masked hyperthyroidism. Scintigraphic examination reveals autonomic nodules of the thyroid glands being frequently a cause of cardiac arrhythmias. Ultrasound examination enables confirmation of the diagnosed autonomic thyroid nodules without TSH test. In the majority of cases of cardiac arrhythmias therapy with radioactive iodine isotope was introduced. Some patients with appropriate indications have been treated surgically after proper preparation. Pharmacological treatment in thyroid-cardiac syndrome produces transient and instable result.