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Background: Physiological experiments have shown that the mean arterial blood pressure (MAP) can not be regulated after chemo and cardiopulmonary receptor denervation. Neuro-physiological information suggests that the nucleus tractus solitarius (NTS) is the only structure that receives information from its rostral neural nuclei and from the cardiovascular receptors and projects to nuclei that regulate the circulatory variables.Methods: From a control theory perspective, to answer if the cardiovascular regulation has a set point, we should find out whether in the cardiovascular control there is something equivalent to a comparator evaluating the error signal (between the rostral projections to the NTS and the feedback inputs). The NTS would function as a comparator if: a) its lesion suppresses cardiovascular regulation; b) the negative feedback loop still responds normally to perturbations (such as mechanical or electrical) after cutting the rostral afferent fibers to the NTS; c) perturbation of rostral neural structures (RNS) to the NTS modifies the set point without changing the dynamics of the elicited response; and d) cardiovascular responses to perturbations on neural structures within the negative feedback loop compensate for much faster than perturbations on the NTS rostral structures.Results: From the control theory framework, experimental evidence found currently in the literature plus experimental results from our group was put together showing that the above-mentioned conditions (to show that the NTS functions as a comparator) are satisfied.Conclusions: Physiological experiments suggest that long-term blood pressure is regulated by the nervous system. The NTS functions as a comparator (evaluating the error signal) between its RNS and the cardiovascular receptor afferents and projects to nuclei that regulate the circulatory variables. The mean arterial pressure (MAP) is regulated by the feedback of chemo and cardiopulmonary receptors and the baroreflex would stabilize the short term pressure value to the prevailing carotid MAP. The discharge rates of rostral neural projections to the NTS would function as the set point of the closed and open loops of cardiovascular control. No doubt, then, the RNS play a functional role not only under steady-state conditions, but also in different behaviors and pathologies. [ABSTRACT FROM AUTHOR]

Honor thy father and thy mother, say the Holy Scriptures1, for they at least gave thee this biological life, but honor thy teachers, too, for they gave thee knowledge and example.Leslie Alexander Geddes took off on a long, long trip, Sunday October 25, 2009, leaving his body for medical and research use. The departing station was West Lafayette, Indiana, where he set foot in 1974, at Purdue University, stamping there a unique deep imprint, similar and probably more profound than the one left at Baylor College of Medicine (BCM), Houston, Texas, in the period 1955-1974. Memories came back as a flood the minute after a message broke the news to me: When I first met him visiting the Department of Physiology at BCM back in 1962, my first Classical Physiology with Modern Instrumentation Summer Course ... The versatile Physiograph was the main equipment, an electronic-mechanical three or four channel recorder that could pick up a variety of physiological variables. Les and his collaborators had introduced also the impedance pneumograph, which was a simplified version of previous developments made by others. It became a ubiquitous unit that trod many roads in the hands of eager and curious students. Ventricular fibrillation and especially its counterpart, defibrillation, stand out as subjects occupying his concern along the years. Many were the students recruited to such effort and long is the list of papers on the subject. Physiological signals attracted considerable part of his activities because one of his perennial mottos was measurement is essential in physiology. He has written thirteen books and over eight hundred scientific papers, receiving also several prizes and distinctions. Not only his interests stayed within the academic environment but an industrial hue was manifested in over 20 USA patents, all applied to medical use. History of science and technology was another area in which, often with Hebbel Hoff, he uncovered astounding and delightful information. It is beyond my capability to review everything Les did, least of all what he did during the long span at Purdue. [ABSTRACT FROM AUTHOR]

In very old days past, I used to play piano, but not anymore. Age wore out the fingers, but they are not rusty.

It is said that time marches on, and one thing is certain: Hearing loss marches right along with it.1 The recorded history of hearing loss goes back hundreds of years, and attempts to correct hearing loss have been in existence since the very first person to cup a hand behind one ear. The good news is hearing aids and other assistive listening devices have come a long way since the first rudimentary attempts at improving hearing. Yes, hearing aid technology is still evolving and is still far from perfect. Well, nothing is perfect in life, as perfection is always an unreachable limit.

The title refers to the conceptual quality of being similar, as a kind of resemblance between both procedures.

The term Organismic Sets described a puzzling and difficult area of research that apparently appears nowadays forgotten, for recent publications cannot be pinpointed. The objective here intends to find out what this subject deals with, not trying to go deeper in its intrincacies, for it would exceed by far the possibilities of the article. Instead, the article only calls the attention and perhaps stimulates the young mathematically oriented researcher.

Dreadful culprits from the minuscule world, indeed, but … what about poverty, war, and terrorism in the macroscopic nowadays world?

Numbers, numbers, they endessly fill out our life… weight, height and many other more hidden body attributes, too, like chronobiological parameters! Fat and thin woman, by Lyudmyla Kharlamova.

Medicine aims toward restoring, maintaining, and improving human health, and engineering aims toward restoring, maintaining and improving human wellness. Both disciplines apply knowledge from science and technology at large to accomplish such objectives. Bioengineering, also called biomedical engineering, is defined as the application of engineering principles and techniques to problems in medicine and biology (always with restoration, maintenance, and improvement in mind), which now also includes veterinary medicine, and the environment in general.

Recognition of true merits may not be a common virtue of the human being, as often achievements are either forgotten, not seen or just buried into oblivion. History of science has plenty of examples, occasionally tainted by endless and useless accusations or even lawsuits leading nowhere.

A biological pacemaker is one or more types of cellular components that, when implanted into certain regions of the heart, produce electrical stimuli that mimic that of the body's natural pacemaker cells. Somatic gene transfer, cell fusion, or cell transplantation provide a way to realize it as somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the possibilities. The idea, no doubt, is bright and appealing. The objective herein intends to dig into the subject trying to find out how realizable it really is.

Background: The rehabilitation process is a fundamental stage for recovery of people's capabilities. However, the evaluation of the process is performed by physiatrists and medical doctors, mostly based on their observations, that is, a subjective appreciation of the patient's evolution. This paper proposes a tracking platform of the movement made by an individual's upper limb using Kinect sensor(s) to be applied for the patient during the rehabilitation process. The main contribution is the development of quantifying software and the statistical validation of its performance, repeatability, and clinical use in the rehabilitation process., Methods: The software determines joint angles and upper limb trajectories for the construction of a specific rehabilitation protocol and quantifies the treatment evolution. In turn, the information is presented via a graphical interface that allows the recording, storage, and report of the patient's data. For clinical purposes, the software information is statistically validated with three different methodologies, comparing the measures with a goniometer in terms of agreement and repeatability., Results: The agreement of joint angles measured with the proposed software and goniometer is evaluated with Bland-Altman plots; all measurements fell well within the limits of agreement, meaning interchangeability of both techniques. Additionally, the results of Bland-Altman analysis of repeatability show 95% confidence. Finally, the physiotherapists' qualitative assessment shows encouraging results for the clinical use., Conclusion: The main conclusion is that the software is capable of offering a clinical history of the patient and is useful for quantification of the rehabilitation success. The simplicity, low cost, and visualization possibilities enhance the use of the software Kinect for rehabilitation and other applications, and the expert's opinion endorses the choice of our approach for clinical practice. Comparison of the new measurement technique with established goniometric methods determines that the proposed software agrees sufficiently to be used interchangeably.

Education is no doubt the foundation of any healthy society. When it is lacking or substandard in quality, all sorts of misery may arise, from poverty and disease to outright delinquency and destructive (or even self-destructive) behavior. The daily news from all around this troubled world often appalls and frightens us: such atrocious and disgraceful behavior generates a vicious cycle that serves to stir up even greater depravity. It is my contention that most, if not all, of these barbarities could be prevented if more people were provided the opportunity for a well-rounded, thoughtfully conceived education [1].

The word analogy is a synonym of likeness, resemblance, similitude, or affinity and involves two concepts being placed side by side, as in a comparison [1]. The workings of nature and those of human societies are amenable to such analogous comparison-even though the evolution of the natural world obviously spans millions of years [2], while human societies are much younger, relatively puppies by comparison. This article considers two interesting examples from these two realms that show remarkable similarities (possibly a result of sheer chance), i.e., a circulatory brain anastomosis, the circle of Willis (CW), and modern power transmission-distribution systems in the ring arrangement. Remember that electric networks handle the flow of charges [say, in coulombs per second (C/s) or electric charge per unit time, which is current), whereas hydraulic systems deal with fluid flow [say, in liters per minutes (L/min) or volume/unit time or fluid mass/unit time]. Hence, these systems too are analogous, a well-known fact often mentioned by instructors of electrical engineering courses.

The relationship among cardiac pacemakers is characterized by the fact that one pacemaker is usually dominant and all the others are subsidiary. The sinoatrial node acts as the dominant pacemaker, and all other potential pacemaker tissues are discharged by a conducted impulse before their respective diastolic depolarizations attain threshold. These pacemakers are called subsidiary to emphasize the fact that, under normal circumstances, they are engaged in conducting impulses, but, under abnormal circumstances, they may become actual pacemakers.

Medical science developed in tandem with the evolution of biological species and their associated diseases. Because of the close interaction between humans and other animals, even those in the wild, taking care of the former also means caring for the latter. Several scientific forerunners delved into animals' anatomical and physiological secrets in their quest to better understand animal biology and functions, thereby laying the foundation for animal medicine. Here, I briefly explore the long and complex road that led to the current state of veterinary science and provide a few examples of its present standing. (Contributions from the ancient world and eastern countries are not considered, as they represent a different area of interest.).

Recently, during the Christmas season, a friend of mine visited me and, sneaking a look at my bookshelves, found two rather old Nikola Tesla biographies, which I had used to prepare a "Retrospectroscope" column for the then-named IEEE Engineering in Medicine and Biology Magazine when our dear friend Alvin Wald was its editor-inchief [2]. Eighteen years have elapsed since then; soon, the idea came up of revamping the article. Cynthia Weber, the magazine's current associate editor, considered it acceptable, and here is the new note divided in two parts: that is, a slightly revised version of the original article followed by new material, including some quite interesting information regarding Tesla's homes and laboratories. On top of this, Tesla is not devoid of a science fiction touch, as mentioned at the end.

The universe is the most fundamental wonder: we, as humans, face it every day, contemplate it in endless amazement, question it in our search for answers. And long ago, at a particular moment in a tiny piece of that great wonder, a second wonder, perhaps deeper in reach, emerged: life. Then, slowly, life evolved to contain within it a third wonder, possibly greater in some respects than the universe itself: the human mind.

The origins of convolution and its further and rather complex historical development were dealt with in detail by Alejandro Dominguez in a previous article [1]. We saw there that it can be traced back to the middle of the 18th century; however, its modern form and use are not more than 50 or 60 years old.

A previous "Retrospectroscope" note, published early in 2014, dealt with spirometry: it described many apparatuses used to measure the volume of inhaled and exhaled air that results from breathing [1]. Such machines, when adequately modified, are also able to measure the rate at which work is produced (specifically by an animal or a human being). Metabolism in that sense is the term used by physiologists and physicians, a word that in Greek, metabolismos, means "change" or "overthrow," in the sense of breaking down material, as in burning some stuff.

Music, along with its attached rhythm, has been with man for centuries, developing and evolving along with him. Its influence on human behavior and mood can reach levels whose limits are still unknown, especially in everything related to perception, where the whole nervous system is involved. Thus, physiology and psychology become strongly connected areas, while technology, through, for example, the production of music by electronic means, appears as a new unexpected ingredient that traditional composers and musicians of older times could not imagine. Obviously, bioengineering and its multiple branches are not absent either [1]?[4]. The literature is enormous with several specialized journals. When one looks back in time at the evolution of this complex area, the appearance of some kind of sudden jump (as a step function), which took place within a relatively recent short interval, is evident: music is now much more than what it used to be, and rhythm has made a step forward as if resurrecting and renewing the ancient Indian or African drums.

My father was always studying, full of dedication and encouragement, my mother always pushed me to study, later on my wife, during our 55 years together, backed me up to study while she also kept studying… all three of them, unrelentingly, almost stubbornly, but always joyfully, even in the worst troubled moments … What else could I do? Besides, and more importantly, isn't it nice, good, rewarding, liberating, to fill the spirit while looking up into the skies, away from the worldly thorns and its forever crazy self-destructing search of money and power? Finally, and most relevant, a full spirit may alleviate human pains.

A 12-yr-old child, with a history of gestational Erb-Duchenne palsy and, later, musculoskeletal injuries in the left arm caused by a car accident, inspired the design of a customized exoskeleton-like device. Such piece, intended for rehabilitation, has one degree of freedom because the exercise routine involves elbow flexion-extension, which was indicated for the damaged muscular group. The device has two functioning modes, passive and assisted, in which the patient can trigger the movement by a biceps contraction, thus promoting the active role of the user in the rehabilitation process. The results were evaluated in terms of qualitative measures of the biceps and the triceps performed by the medical staff and by a questionnaire related to functional activities of the upper limb. A significant improvement in the arm movement and elbow angle was observed after 3 mos of assisted therapy, complementary to conventional exercises. In conclusion, a simple and low-cost device was designed and tested to complement the rehabilitation process of a pediatric patient with physical impairment.

Background: This work evaluates the vectorcardiographic dynamic changes in ischemic patients before and during Percutaneous Transluminal Coronary Angioplasty (PTCA)., Methods: Four QRS-loop parameters were computed in 51 ischemic and 52 healthy subjects with the objective of assessing the vectorcardiographic differences between both groups: maximum vector magnitude (QRS(mVM)), planar area (QRS(PA)), maximum distance between centroid and loop (QRS(mDCL)) and perimeter (QRS(P)).The conventional ST-change vector magnitude (STC(VM)), QRS-vector difference (QRS(VD)) and spatial ventricular gradient (SVG) were also calculated., Results: Statistical minute-by-minute PTCA comparison against a healthy population showed that ischemic patients monitoring is greatly enhanced when all the QRS-loop parameters, in combination with the standard STC(VM), QRS(VD) and SVG indexes, are used in the classification. Sensitivity and Specificity, in turn, reached rather high values, 95.4% and 95.2%, respectively., Conclusions: These new vectorcardiographic set of complementary QRS-loop parameters, when combined with the classics STC(VM), QRS(VD) and SVG indexes, increase sensitivity and specificity for acute ischemia monitoring., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Think about the above lines taken from the Old Testament: At 130 years of age, Adam begat a son and at 800 he kept going, quitting this earthly life at 930. These numbers surpass by far the limits our current experience teaches us, however, perhaps a life span into the hundreds of years is ? What if, in the future, science were to do away with disease? What then would cause people to die: accidents, killings, wars? How old would old age be? Aging has always been a hot topic for research (with considerable quackery, too). For example, animals with a slow metabolism tend to live longer than those with a fast metabolism. Compare the average life span of a mouse with that of a turtle. Apparently, meditators are able to slow their metabolism down [1].

New signal processing techniques have enabled the use of the vectorcardiogram (VCG) for the detection of cardiac ischemia. Thus, we studied this signal during ventricular depolarization in 80 ischemic patients, before undergoing angioplasty, and 52 healthy subjects with the objective of evaluating the vectorcardiographic difference between both groups so leading to their subsequent classification. For that matter, seven QRS-loop parameters were analyzed, i.e.: (a) Maximum Vector Magnitude; (b) Volume; (c) Planar Area; (d) Maximum Distance between Centroid and Loop; (e) Angle between XY and Optimum Plane; (f) Perimeter and, (g) Area-Perimeter Ratio. For comparison, the conventional ST-Vector Magnitude (ST(VM)) was also calculated. Results indicate that several vectorcardiographic parameters show significant differences between healthy and ischemic subjects. The identification of ischemic patients via discriminant analysis using ST(VM) produced 73.2% Sensitivity (Sens) and 73.9% Specificity (Spec). In our study, the QRS-loop parameter with the best global performance was Volume, which achieved Sens=64.5% and Spec=74.6%. However, when all QRS-loop parameters and ST(VM) were combined, we obtained Sens=88.5% and Spec=92.1%. In conclusion, QRS loop parameters can be accepted as a complement to conventional ST(VM) analysis in the identification of ischemic patients., (Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.)

On the basis of the strict exclusion of the vis vitalis, the demand was raised by Carl Ludwig, Helmholtz, Du Bois-Reymond, and Brucke for a physiology which was causal-analytical and physically and chemically experimental. If, out of these four investigators, we pick Ludwig as the actual founder of modern physiology, the grounds for this must be justified specifically. That modern physiology is not to be contemplated without the works of the three great students of Johannes Muller is explicitly emphasized. However, Carl Ludwig occupies a special position for physiology.

Background: An allometric relationship between different electrocardiogram (ECG) parameters and infarcted ventricular mass was assessed in a myocardial infarction (MI) model in New Zealand rabbits., Methods: A total of fifteen animals were used, out of which ten underwent left anterior descending coronary artery ligation to induce infarction (7-35% area). Myocardial infarction (MI) evolved and stabilized during a three month-period, after which, rabbits were sacrificed and the injured area was histologically confirmed. Right before sacrifice, ECGs were obtained to correlate several of its parameters to the infarcted mass. The latter was normalized after combining data from planimetry measurements and heart weight. The following ECG parameters were studied: RR and PR intervals, P-wave duration (PD), QRS duration (QRSD) and amplitude (QRSA), Q-wave (QA), R-wave (RA) and S-wave (SA) amplitudes, T-wave peak amplitude (TA), the interval from the peak to the end of the T-wave (TPE), ST-segment deviation (STA), QT interval (QT), corrected QT and JT intervals. Corrected QT was analyzed with different correction formulae, i.e., Bazett (QTB), Framingham (QTFRA), Fridericia (QTFRI), Hodge (QTHO) and Matsunaga (QTMA) and compared thereafter. The former variables and infarcted ventricular mass were then fitted to the allometric equation in terms of deviation from normality, in turn derived after ECGs in 5 healthy rabbits., Results: Six variables (JT, QTB, QA, SA, TA and STA) presented statistical differences among leads. QT showed the best allometric fit (r = 0.78), followed by TA (r = 0.77), STA (r = 0.75), QTFRA (r = 0.72), TPE (r = 0.69), QTFRI (r = 0.68) and QTMA (r = 0.68). Corrected QT's (QTFRA, QTFRI and QTMA) performed worse than the uncorrected counterpart (QT), the former scaling allometrically with similar goodness of fits., Conclusions: QT, TA, STA and TPE could possibly be used to assess infarction extent in an old MI event through the allometric model as a first approach. Moreover, the TPE also produced a good allometric scaling, leading to the potential existence of promising allometric indexes to diagnose malignant arrhythmias.

The evolution and development of hospitals in their historical context are quickly reviewed in this column, starting first as simple shelters for the sick and indigent who were waiting essentially for death, and up to the relatively recent concept of true health centers where patients face a high probability of actual recovery and rehabilitation. Anesthesia, microbiology, asepsia, antibiotics, virology, radiology, transfusion, and different biomedical engineering technologies, as well as knowledge in other basic sciences, have led to the intensive care and emergency units that were introduced in the 1960s, which lead to the specialty of critical care medicine and positioning the patient as the center of care. These brief words anticipate what we develop below.

Background: The notion of the nucleus tractus solitarius (NTS) as a comparator evaluating the error signal between its rostral neural structures (RNS) and the cardiovascular receptor afferents into it has been recently presented. From this perspective, stress can cause hypertension via set point changes, so offering an answer to an old question. Even though the local blood flow to tissues is influenced by circulating vasoactive hormones and also by local factors, there is yet significant sympathetic control. It is well established that the state of maturation of sympathetic innervation of blood vessels at birth varies across animal species and it takes place mostly during the postnatal period. During ontogeny, chemoreceptors are functional; they discharge when the partial pressures of oxygen and carbon dioxide in the arterial blood are not normal., Methods: The model is a simple biological plausible adaptative neural network to simulate the development of the sympathetic nervous control. It is hypothesized that during ontogeny, from the RNS afferents to the NTS, the optimal level of each sympathetic efferent discharge is learned through the chemoreceptors' feedback. Its mean discharge leads to normal oxygen and carbon dioxide levels in each tissue. Thus, the sympathetic efferent discharge sets at the optimal level if, despite maximal drift, the local blood flow is compensated for by autoregulation. Such optimal level produces minimum chemoreceptor output, which must be maintained by the nervous system. Since blood flow is controlled by arterial blood pressure, the long-term mean level is stabilized to regulate oxygen and carbon dioxide levels. After development, the cardiopulmonary reflexes play an important role in controlling efferent sympathetic nerve activity to the kidneys and modulating sodium and water excretion., Results: Starting from fixed RNS afferents to the NTS and random synaptic weight values, the sympathetic efferents converged to the optimal values. When learning was completed, the output from the chemoreceptors became zero because the sympathetic efferents led to normal partial pressures of oxygen and carbon dioxide., Conclusions: We introduce here a simple simulating computational theory to study, from a neurophysiologic point of view, the sympathetic development of cardiovascular regulation due to feedback signals sent off by cardiovascular receptors. The model simulates, too, how the NTS, as emergent property, acts as a comparator and how its rostral afferents behave as set point.

Background: Allometry, in general biology, measures the relative growth of a part in relation to the whole living organism. Using reported clinical data, we apply this concept for evaluating the probability of ventricular fibrillation based on the electrocardiographic ST-segment deviation values., Methods: Data collected by previous reports were used to fit an allometric model in order to estimate ventricular fibrillation probability. Patients presenting either with death, myocardial infarction or unstable angina were included to calculate such probability as, VFp = δ + β (ST), for three different ST deviations. The coefficients δ and β were obtained as the best fit to the clinical data extended over observational periods of 1, 6, 12 and 48 months from occurrence of the first reported chest pain accompanied by ST deviation., Results: By application of the above equation in log-log representation, the fitting procedure produced the following overall coefficients: Average β = 0.46, with a maximum = 0.62 and a minimum = 0.42; Average δ = 1.28, with a maximum = 1.79 and a minimum = 0.92. For a 2 mm ST-deviation, the full range of predicted ventricular fibrillation probability extended from about 13% at 1 month up to 86% at 4 years after the original cardiac event., Conclusions: These results, at least preliminarily, appear acceptable and still call for full clinical test. The model seems promising, especially if other parameters were taken into account, such as blood cardiac enzyme concentrations, ischemic or infarcted epicardial areas or ejection fraction. It is concluded, considering these results and a few references found in the literature, that the allometric model shows good predictive practical value to aid medical decisions.

Biomedical engineering is clearly present in modern neuroendocrinology, and indeed has come to embrace it in many respects. First, we briefly review the origins of endocrinology until neuroendocrinology, after a long saga, was established in the 1950's decade with quantified results made possible by the radioimmunoassay technique (RIA), a development contributed by the physical sciences. However, instrumentation was only one face of the quantification process, for mathematical models aiding in the study of negative feedback loops, first rather shyly and now at a growing rate, became means building the edifice of mathematical neuroendocrinology while computer assisted techniques help unravel the associated genetic aspects or the nature itself of endocrine bursts by numerical deconvolution analysis. To end the note, attention is called to the pleiotropic characteristics of neuroendocrinology, which keeps branching off almost endlessly as bioengineering does too.

This paper discussed how the bioengineering and medical engineering started in Argentina.