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Journal of the American College of... Oct 1997Among mammals, there is an inverse semilogarithmic relation between heart rate and life expectancy. The product of these variables, namely, the number of heart... (Comparative Study)
Comparative Study Review
Among mammals, there is an inverse semilogarithmic relation between heart rate and life expectancy. The product of these variables, namely, the number of heart beats/lifetime, should provide a mathematical expression that defines for each species a predetermined number of heart beats in a lifetime. Plots of the calculated number of heart beats/lifetime among mammals against life expectancy and body weight (allometric scale of 0.5 x 10(6)) are, within an order of magnitude, remarkably constant and average 7.3 +/- 5.6 x 10(8) heart beats/lifetime. A study of universal biologic scaling and mortality suggests that the basal energy consumption/body atom per heart beat is the same in all animals (approximately 10(-8) O2 molecules/heart beat). These data yield a mean value of 10 x 10(8) heart beats/lifetime and suggest that life span is predetermined by basic energetics of living cells and that the apparent inverse relation between life span and heart rate reflects an epiphenomenon in which heart rate is a marker of metabolic rate. Thus, the question of whether human life can be extended by cardiac slowing remains moot and most likely will only be resolved by retrospective analyses of large populations, future animal studies and clinical trials using bradycardic therapy.
Topics: Animals; Body Temperature; Body Weight; Energy Intake; Energy Metabolism; Exercise; Heart Rate; Humans; Life Expectancy; Mammals; Rest
PubMed: 9316546
DOI: 10.1016/s0735-1097(97)00246-5 -
Physical Review. E Apr 2023The fluctuation relation, a milestone of modern thermodynamics, is only established when a set of fundamental currents can be measured. Here we prove that it also holds...
The fluctuation relation, a milestone of modern thermodynamics, is only established when a set of fundamental currents can be measured. Here we prove that it also holds for systems with hidden transitions if observations are carried "at their own beat," that is, by stopping the experiment after a fixed number of visible transitions, rather than the elapse of an external clock time. This suggests that thermodynamic symmetries are more resistant to the loss of information when described in the space of transitions.
PubMed: 37198803
DOI: 10.1103/PhysRevE.107.L042105 -
American Journal of Lifestyle Medicine 2021There is a tendency to accept anxiety as an inevitable part of living in a stressful modern world. However, simple dietary changes can help attenuate the stress...
There is a tendency to accept anxiety as an inevitable part of living in a stressful modern world. However, simple dietary changes can help attenuate the stress response. While there are several approaches to treating anxiety, research by Peter Roy-Byrne in 2015 has shown that only 50% to 60% of people respond to medication and psychotherapy, and only a quarter of patients have complete resolution of their symptoms. According to statistics from the National Institute of Mental health, prior to the COVID-19 pandemic, anxiety disorders were the most common mental health disorder in the United States, about 3 times more common than depression (18.1% vs 6.7%). A recent Express Scripts survey showed the percent increase in the number of new prescriptions for antianxiety medications by the middle March 2020 for antianxiety medications was 37.7%, underscoring the likely rise in anxiety associated with the pandemic. While traditional medications and therapies are well needed, to beat stress during times of a pandemic, it is important to think more broadly about how we can best affect our mental well-being. One of those ways is through our nutrition and dietary habits, and research by Opie et al in 2015 demonstrates that our dietary choices are more crucial than ever. This column reviews foods and substances that are important to consider in managing anxiety.
PubMed: 33456419
DOI: 10.1177/1559827620973936 -
The Journal of Experimental Biology Mar 2021Many quadrupedal mammals transition from a four-beat walk to a two-beat run (e.g. trot), but some transition to a four-beat run (e.g. amble). Recent analysis shows that...
Many quadrupedal mammals transition from a four-beat walk to a two-beat run (e.g. trot), but some transition to a four-beat run (e.g. amble). Recent analysis shows that a two-beat run minimizes work only for animals with a small pitch moment of inertia (MOI), though empirical MOI were not reported. It was also unclear whether MOI affects gait energetics at slow speeds. Here, I show that a particular normalization of the pitch moment of inertia (the Murphy number) has opposite effects on walking and running energetics. During walking, simultaneous forelimb and hindlimb contacts dampen pitching energy, favouring a four-beat gait that can distribute expensive transfer of support. However, the required pitching of a four-beat walk becomes more expensive as Murphy number increases. Using trajectory optimization of a simple model, I show that both the walking and slow running strategies used by dogs, horses, giraffes and elephants can be explained by work optimization under their specific Murphy numbers. Rotational dynamics have been largely ignored in quadrupedal locomotion, but appear to be a central factor in gait selection.
Topics: Animals; Biomechanical Phenomena; Dogs; Forelimb; Gait; Hindlimb; Horses; Running; Walking
PubMed: 33462135
DOI: 10.1242/jeb.228296 -
Annals of Noninvasive Electrocardiology... Sep 2017Cardiac restitution is the ability of the heart to recover from one beat to the next. Ventricular arrhythmia vulnerability can occur when the heart does not properly... (Review)
Review
BACKGROUND
Cardiac restitution is the ability of the heart to recover from one beat to the next. Ventricular arrhythmia vulnerability can occur when the heart does not properly adjust to sudden changes in rate or in hemodynamics leading to excessive temporal and/or spatial heterogeneity in conduction or repolarization. Restitution has historically been used to study, by invasive means, the dynamics of the relationship between action potential duration (APD) and diastolic interval (DI) in sedated subjects using various pacing protocols. Even though the analogous measures of APD and DI can be obtained using the surface ECG to acquire the respective QT and TQ intervals for ECG restitution, this methodology has not been widely adopted for a number of reasons.
METHODS
Recent development of more advanced software algorithms enables ECG intervals to be measured accurately, on a continuous beat-to-beat basis, in an automated manner, and under highly dynamic conditions (i.e., ambulatory or exercise) providing information beyond that available in the typical resting state.
RESULTS
Current breakthroughs in ECG technology will allow ECG restitution measures to become a practical approach for providing quantitative measures of the risks for ventricular arrhythmias as well as cardiac stress in general.
CONCLUSIONS
In addition to a review of the underlying principles and caveats of ECG restitution, a new approach toward an advancement of more integrated restitution biomarkers is proposed.
Topics: Biomarkers; Electrocardiography; Heart; Humans; Tachycardia, Ventricular
PubMed: 28497858
DOI: 10.1111/anec.12460 -
Genes Feb 2021Determination of the relative copy numbers of mixed molecular species in nucleic acid samples is often the objective of biological experiments, including...
Determination of the relative copy numbers of mixed molecular species in nucleic acid samples is often the objective of biological experiments, including Single-Nucleotide Polymorphism (SNP), indel and gene copy-number characterization, and quantification of CRISPR-Cas9 base editing, cytosine methylation, and RNA editing. Standard dye-terminator chromatograms are a widely accessible, cost-effective information source from which copy-number proportions can be inferred. However, the rate of incorporation of dye terminators is dependent on the dye type, the adjacent sequence string, and the secondary structure of the sequenced strand. These variable rates complicate inferences and have driven scientists to resort to complex and costly quantification methods. Because these complex methods introduce their own biases, researchers are rethinking whether rectifying distortions in sequencing trace files and using direct sequencing for quantification will enable comparable accurate assessment. Indeed, recent developments in software tools (e.g., TIDE, ICE, EditR, BEEP and BEAT) indicate that quantification based on direct Sanger sequencing is gaining in scientific acceptance. This commentary reviews the common obstacles in quantification and the latest insights and developments relevant to estimating copy-number proportions based on direct Sanger sequencing, concluding that bidirectional sequencing and sophisticated base calling are the keys to identifying and avoiding sequence distortions.
Topics: CRISPR-Cas Systems; DNA Copy Number Variations; Gene Dosage; INDEL Mutation; Polymorphism, Single Nucleotide; RNA Editing; Sequence Analysis, DNA; Software
PubMed: 33671263
DOI: 10.3390/genes12020283 -
PloS One 2018Perception of a regular beat in music is inferred from different types of accents. For example, increases in loudness cause intensity accents, and the grouping of time...
Perception of a regular beat in music is inferred from different types of accents. For example, increases in loudness cause intensity accents, and the grouping of time intervals in a rhythm creates temporal accents. Accents are expected to occur on the beat: when accents are "missing" on the beat, the beat is more difficult to find. However, it is unclear whether accents occurring off the beat alter beat perception similarly to missing accents on the beat. Moreover, no one has examined whether intensity accents influence beat perception more or less strongly than temporal accents, nor how musical expertise affects sensitivity to each type of accent. In two experiments, we obtained ratings of difficulty in finding the beat in rhythms with either temporal or intensity accents, and which varied in the number of accents on the beat as well as the number of accents off the beat. In both experiments, the occurrence of accents on the beat facilitated beat detection more in musical experts than in musical novices. In addition, the number of accents on the beat affected beat finding more in rhythms with temporal accents than in rhythms with intensity accents. The effect of accents off the beat was much weaker than the effect of accents on the beat and appeared to depend on musical expertise, as well as on the number of accents on the beat: when many accents on the beat are missing, beat perception is quite difficult, and adding accents off the beat may not reduce beat perception further. Overall, the different types of accents were processed qualitatively differently, depending on musical expertise. Therefore, these findings indicate the importance of designing ecologically valid stimuli when testing beat perception in musical novices, who may need different types of accent information than musical experts to be able to find a beat. Furthermore, our findings stress the importance of carefully designing rhythms for social and clinical applications of beat perception, as not all listeners treat all rhythms alike.
Topics: Adolescent; Adult; Aged; Auditory Perception; Female; Humans; Male; Middle Aged; Music
PubMed: 29320533
DOI: 10.1371/journal.pone.0190322 -
Hypertension Research : Official... Apr 2022Despite the challenges associated with the coronavirus pandemic, the last 2 years have been active periods for hypertension research and initiatives in Asia. There are...
Despite the challenges associated with the coronavirus pandemic, the last 2 years have been active periods for hypertension research and initiatives in Asia. There are new hypertension guidelines from the World Health Organization that can be interpreted and applied locally. This is also the case for data from the latest Blood Pressure Lowering Treatment Trialists' Collaboration meta-analysis, which showed that greater reductions in systolic blood pressure (BP) are associated with lower risks of cardiovascular events. The randomized controlled Strategy of Blood Pressure Intervention in the Elderly Hypertensive study and the Salt Substitute and Stroke Study provide local data to inform practice. Other initiatives to help reduce high salt intake in Asia are also underway. Both drug-resistant and nocturnal hypertension are appropriate areas of focus in Asia, and there are an increasing number of pharmacological and non-pharmacological treatment options for these conditions. Digital therapeutics to promote uptake and implementation of lifestyle interventions are showing promise, and other digital-based strategies such as telemedicine, wearable BP monitors to detect beat-by-beat BP and artificial intelligence will no doubt become integral parts of future strategies to reduce the burden of hypertension and hypertension-related disease. A number of initiatives from the Hypertension Cardiovascular Outcome Prevention and Evidence in Asia Network and Japanese Society of hypertension are underway, and there is good reason for optimism regarding the ongoing and future management of hypertension in Asia based on these and the active research activities in the region.
Topics: Aged; Artificial Intelligence; Asia; Blood Pressure; Blood Pressure Monitoring, Ambulatory; Humans; Hypertension
PubMed: 35379955
DOI: 10.1038/s41440-022-00874-8 -
Journal of Arrhythmia Oct 2016Pre-existing heterogeneities present in cardiac tissue are essential for maintaining the normal electrical and mechanical functions of the heart. Exacerbation of such... (Review)
Review
Pre-existing heterogeneities present in cardiac tissue are essential for maintaining the normal electrical and mechanical functions of the heart. Exacerbation of such heterogeneities or the emergence of dynamic factors can produce repolarization alternans, which are beat-to-beat alternations in the action potential time course. Traditionally, this was explained by restitution, but additional factors, such as cardiac memory, calcium handling dynamics, refractory period restitution, and mechano-electric feedback, are increasingly recognized as the underlying causes. The aim of this article is to review the mechanisms that generate cardiac repolarization alternans and convert spatially concordant alternans to the more arrhythmogenic spatially discordant alternans. This is followed by a discussion on how alternans generate arrhythmias in a number of clinical scenarios, and concluded by an outline of future therapeutic targets for anti-arrhythmic therapy.
PubMed: 27761166
DOI: 10.1016/j.joa.2016.02.009