scholarly journals Concepts in human biological rhythms

2003 ◽  
Vol 5 (4) ◽  
pp. 327-342 ◽  
Keyword(s):  
Experimental Data ◽  
Genetic Model ◽  
Clinical Symptoms ◽  
Night Shift ◽  
Biological Rhythms ◽  
Temporal Organization ◽  
Biological Clocks ◽  
Shift Workers ◽  
Left Hand ◽  
The Right

Biological rhythms and their temporal organization are adaptive phenomena to periodic changes in environmental factors linked to the earth's rotation on its axis and around the sun. Experimental data from the plant and animal kingdoms have led to many models and concepts related to biological clocks that help describe and understand the mechanisms of these changes. Many of the prevailing concepts apply to all organisms, but most of the experimental data are insufficient to explain the dynamics of human biological clocks. This review presents phenomena thai are mainly characteristic ofand unique to - human chronobiology, and which cannot be fully explained by concepts and models drawn from laboratory experiments. We deal with the functional advantages of the human temporal organization and the problem of desynchronization, with special reference to the period (τ) of the circadian rhythm and its interindividual and intraindividual variability. We describe the differences between right- and left-hand rhythms suggesting the existence of different biological clocks in the right and left cortices, Desynchronization of rhythms is rather frequent (one example is night shift workers). In some individuals, desynchronization causes no clinical symptoms and we propose the concept of "allochronism" to designate a variant of the human temporal organization with no pathological implications. We restrict the term "dyschronism" to changes or alterations in temporal organization associated with a set of symptoms similar to those observed in subjects intolerant to shift work, eg, persisting fatigue and mood and sleep alterations. Many diseases involve chronic deprivation of sleep at night and constitute conditions mimicking thai of night shift workers who are intolerant to desynchronization. We also present a genetic model (the dian-circadian model) to explain interindividual differences in the period of biological rhythms in certain conditions.

scholarly journals Chronobiology and the design of marine biology experiments

2018 ◽  
Vol 76 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Audrey M Mat
Keyword(s):  
Marine Biology ◽  
Clock Genes ◽  
Biological Rhythms ◽  
Marine Species ◽  
Temporal Organization ◽  
Biological Clocks ◽  
Solar Cycles ◽  
Dark Cycle ◽  
Marine Habitats ◽  
Selection Of

AbstractMarine habitats are shaped by several geophysical cycles ranging from a few hours (tidal and solar cycles) to a year (seasons). These cycles have favoured the selection of endogenous biological clocks. Such a clock is a molecular time-keeping mechanism that consists of a set of core clock genes whose expression oscillates. The clocks produce biological rhythms and influence virtually all metabolic, physiological, and behavioural functions in organisms. This work highlights the importance to take chronobiology into account in experimental marine biology to avoid faulty results, misinterpretation of results, and/or to strengthen observations and conclusion. A literature survey, based on 150 articles, was conducted and showed that, despite the pervasive imprint of biological rhythms in marine species, environmental cycles such as the 24 h-light/dark cycle and the seasonality are rarely considered in experimental designs. This work emphasizes that better integrating the temporal organization and regulation of marine species within the marine biology community is essential for obtaining representative results.

Prediction of Forming Limit of Sheet Metal Based on Stören-Rice Model

2011 ◽  
Vol 221 ◽  
pp. 205-210
Author(s):  
Wei Gang Guo ◽  
Jia Ming Chen ◽  
Hui Min Li ◽  
Li Dong Shao
Keyword(s):  
Experimental Data ◽  
Sheet Metal ◽  
Calculation Result ◽  
Anisotropy Parameter ◽  
Yield Function ◽  
Limit Strain ◽  
Forming Limit ◽  
Left Hand ◽  
A Value ◽  
The Right

On the basis of Storen-Rice model, the limit strain formula is derived by introducing the plasticity constitutive relation coupling Logan-Hosford yield function. Limit strain of AL6111-T4 and AL2028 is calculated and compared with experimental data. The effect of index a of yield function, anisotropy parameter r on the calculation result is discussed. Index a has a significant effect on the right hand side(RHS) limit strain, while it has less relation with left hand side(LHS) limit strain. The RHS limit strain is smaller while a-value gets larger. Good correlation between the calculation result and experimental data is indicated when a-value equals to 4. The RHS limit strain is smaller while r gets larger when a equals to 2, while it has less relation with r when a equals to 4 or 6.

scholarly journals Clinical case of asymptomatic perforation of right ventricle during permanent pacemaker implantation

2019 ◽  
Vol 23 (4) ◽  
pp. 91
Author(s):  
A. N. Verevetinov ◽  
E. S. Tarasyuk ◽  
I. E. Dorovskih ◽  
J. V. Vakhnenko ◽  
V. N. Nikitin ◽  
...  
Keyword(s):  
Right Ventricle ◽  
Conflict Of Interest ◽  
Clinical Case ◽  
Clinical Symptoms ◽  
Pacemaker Implantation ◽  
Myocardial Damage ◽  
Left Hand ◽  
Heart Failure Progression ◽  
Life Threatening ◽  
The Right

<p>The present paper discusses one of the serious complications of electrocardiostimulator implantation: electrode perforation of the right ventricle wall, a condition that can occur in both the early and late postoperative periods. The latter occurs less frequently, and the patient may be asymptomatic; this results in an adverse effect on the patient’s quality of life and disease prognosis. Knowledge about the symptoms of late perforation and algorithms to examine patients suspected to have this complication contributes to timely surgical intervention as well as prevention of heart failure progression and fatal outcomes. This paper describes a clinical case of right ventricular perforation 1.5 years after electrocardiostimulator implantation, wherein, despite the absence of pronounced clinical symptoms, the patient was successfully diagnosed with pacemaker testing, Holter diagnostics, echocardiography and computed tomography of thoracic organs. Myocardial damage was accompanied by small left-hand bone-diaphragm hydrotorax and hydropericardium. The risk factors of perforation in the present case were low body weight and age. In the course of the surgical operation performed with the exact observance of the chosen technique, the integrity of the myocardium of the right ventricle and the function of the electrocardiostimulator were restored. Thus, the life-threatening consequences of the described complication were prevented.</p><p>Received 12 September 2019. Revised 20 December 2019. Accepted 23 December 2019.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p>

scholarly journals The “ECG modifications induced by the disturbance of the circadian rhythm in night-shift workers (ECGNoct)” study protocol

2019 ◽  
Vol 70 (1) ◽  
pp. 12-19
Author(s):  
Marina Ruxandra Oțelea ◽  
Anca Streinu-Cercel ◽  
Daniela Manolache ◽  
Andreea Mutu ◽  
Lavinia Călugăreanu ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Metabolic Diseases ◽  
Clinical Symptoms ◽  
Night Shift ◽  
Screening Tests ◽  
Cross Sectional ◽  
Shift Workers ◽  
Occupational Risk Factors ◽  
The Metabolic Syndrome ◽  
Night Shifts

Abstract In many large cohort studies, the night shift constitutes a risk factor for developing cardiovascular disease and diabetes in workers. Current screening tests for people working in night shift include fasting glycaemia and electrocardiography. In fact, there are few studies focused on the description of the electrocardiographic changes after the night shift. This article describes the protocol of the “ECG modifications induced by the disturbance of the circadian rhythm in night-shift workers (ECGNoct)” study, which was initiated by the National Institute for Infectious Diseases “Prof. Dr. Matei Balș”. Nurses represent the target population. The protocol includes a full medical and occupational history, lifestyle habits (smoking, alcohol, nutrition), anthropometric and blood pressure measurements, blood tests (fasting glycemia, total cholesterol, triglycerides and high density lipoprotein cholesterol) and electrocardiogram recording. For nurses working in (night) shifts, we will record the electrocardiogram before and soon after the night shift. A cross sectional study will analyze the incidence of the metabolic syndrome criteria, the cardio-metabolic diseases and the electrocardiographic modifications and will compare the results between the group of nurses working and the group of nurse who do not. Based on these results, a longitudinal study will test the hypothesis that night shift increases the risk for cardio-metabolic diseases and that the electrocardiographic modifications precede the clinical symptoms. The results of the study will provide data on the association of night shifts and other non-occupational risk factors with the cardio-metabolic diseases in this specific population of healthcare workers that potentially will integrate into the occupational medicine policies.

scholarly journals Timing as a sexually selected trait: the right mate at the right moment

2017 ◽  
Vol 372 (1734) ◽  
pp. 20160249 ◽  
Author(s):  
Michaela Hau ◽  
Davide Dominoni ◽  
Stefania Casagrande ◽  
C. Loren Buck ◽  
Gabriela Wagner ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Seasonal Pattern ◽  
Temporal Organization ◽  
Current Evidence ◽  
Biological Clocks ◽  
Seasonal Timing ◽  
Sexually Selected Traits ◽  
Genetic Components ◽  
Selected Traits ◽  
The Right

Sexual selection favours the expression of traits in one sex that attract members of the opposite sex for mating. The nature of sexually selected traits such as vocalization, colour and ornamentation, their fitness benefits as well as their costs have received ample attention in field and laboratory studies. However, sexually selected traits may not always be expressed: coloration and ornaments often follow a seasonal pattern and behaviours may be displayed only at specific times of the day. Despite the widely recognized differences in the daily and seasonal timing of traits and their consequences for reproductive success, the actions of sexual selection on the temporal organization of traits has received only scant attention. Drawing on selected examples from bird and mammal studies, here we summarize the current evidence for the daily and seasonal timing of traits. We highlight that molecular advances in chronobiology have opened exciting new opportunities for identifying the genetic targets that sexual selection may act on to shape the timing of trait expression. Furthermore, known genetic links between daily and seasonal timing mechanisms lead to the hypothesis that selection on one timescale may simultaneously also affect the other. We emphasize that studies on the timing of sexual displays of both males and females from wild populations will be invaluable for understanding the nature of sexual selection and its potential to act on differences within and between the sexes in timing. Molecular approaches will be important for pinpointing genetic components of biological rhythms that are targeted by sexual selection, and to clarify whether these represent core or peripheral components of endogenous clocks. Finally, we call for a renewed integration of the fields of evolution, behavioural ecology and chronobiology to tackle the exciting question of how sexual selection contributes to the evolution of biological clocks. This article is part of the themed issue ‘Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals’.

scholarly journals Review: Chronopharmacology; A Biological Rhythm

2021 ◽  
Vol 23 (12) ◽  
pp. 60-82
Author(s):  
Pooja P. Dahale ◽  
◽  
Mr. Vijay R. Chakote ◽  
Siddesh V Rokade ◽  
Shrikant C. Bhosale ◽  
...  
Keyword(s):  
Biological Rhythms ◽  
Temporal Variations ◽  
External Factors ◽  
Temporal Organization ◽  
Time Dependent ◽  
Peak Time ◽  
Toxic Substances ◽  
Biological Clocks ◽  
Scientific Domain ◽  
Physiological Variables

Chronopharmacology is the study of how the effects of drugs vary with biological timing and endogenous periodicities. The goal is to improve our understanding of periodic and thus predictable (e.g. circadian) changes in both desired effects (chronoeffectiveness) and tolerance (chronotolerance) of medications. Dosing time-dependent changes also include quantification of parameters characterizing endogenous circadian rhythms (CR), in terms of pharmacologic effects, e.g. the 24-h adjusted mean (M), the period , the amplitude (A, the peak-to-trough difference), and the acrophase , the peak time location in the 24-h scale). Chronopharmacology became recognized as a scientific domain of investigation only in the early 1970s. For conventionally trained pharmacologists, it was not clear that predictable temporal variations of effects and disposition of agents (e.g. medications, hormones, and toxic substances) are governed by endogenous biological rhythms rather than by changes of external factors. On the 24-h scale (as well as on the yearly scale) there are peaks and troughs of physiological variables that are not randomly distributed; their respective locations correspond to a temporal organization controlled by a set of pacemakers (so-called biological clocks) became recognized as a scientific domain of investigation only in the early 1970s.

Editorial Note

1946 ◽  
Vol 11 (1) ◽  
pp. 2-2
Keyword(s):  
Editorial Note ◽  
Speech Sounds ◽  
Left Hand ◽  
Hand Column ◽  
Right Hand ◽  
Infant Speech ◽  
The Right

In the article “Infant Speech Sounds and Intelligence” by Orvis C. Irwin and Han Piao Chen, in the December 1945 issue of the Journal, the paragraph which begins at the bottom of the left hand column on page 295 should have been placed immediately below the first paragraph at the top of the right hand column on page 296. To the authors we express our sincere apologies.

Is the Future the Right Time?

2010 ◽  
Vol 57 (4) ◽  
pp. 308-314 ◽  
Author(s):  
Marc Ouellet ◽  
Julio Santiago ◽  
Ziv Israeli ◽  
Shai Gabay
Keyword(s):  
Auditory Task ◽  
English Speakers ◽  
Visual Modality ◽  
Opposite Pattern ◽  
Time Line ◽  
Temporal Reference ◽  
Left Hand ◽  
Reading Direction ◽  
Mental Time Line ◽  
The Right

Spanish and English speakers tend to conceptualize time as running from left to right along a mental line. Previous research suggests that this representational strategy arises from the participants’ exposure to a left-to-right writing system. However, direct evidence supporting this assertion suffers from several limitations and relies only on the visual modality. This study subjected to a direct test the reading hypothesis using an auditory task. Participants from two groups (Spanish and Hebrew) differing in the directionality of their orthographic system had to discriminate temporal reference (past or future) of verbs and adverbs (referring to either past or future) auditorily presented to either the left or right ear by pressing a left or a right key. Spanish participants were faster responding to past words with the left hand and to future words with the right hand, whereas Hebrew participants showed the opposite pattern. Our results demonstrate that the left-right mapping of time is not restricted to the visual modality and that the direction of reading accounts for the preferred directionality of the mental time line. These results are discussed in the context of a possible mechanism underlying the effects of reading direction on highly abstract conceptual representations.

Off-Pump Supraarterial Decompression Myotomy for Myocardial Bridging

2005 ◽  
Vol 8 (1) ◽  
pp. 49 ◽  
Author(s):  
Mersa M. Baryalei ◽  
Theodorus Tirilomis ◽  
Wolfgang Buhre ◽  
Stephan Kazmaier ◽  
Friedrich A. Schoendube ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Exercise Testing ◽  
Clinical Symptoms ◽  
Therapeutic Option ◽  
Median Sternotomy ◽  
Myocardial Bridging ◽  
Off Pump ◽  
Hemodynamic Compromise ◽  
Artery Disease ◽  
The Right

Background: Myocardial bridging of the left anterior descending (LAD) artery may result in clinical symptoms. Surgery with cardiopulmonary bypass (CPB) is a therapeutic option with considerable risk. We hypothesized that off-pump supraarterial myotomy could be an effective treatment modality. Methods: Between October 1998 and May 2000, 13 patients were referred for surgery. All were symptomatic despite medical therapy. Anteroseptal ischemia had been proven by thallium scintigraphy in all 13 patients, exercise testing was positive in 11. All patients were operated on with an off-pump approach after median sternotomy. Results: Mean patient age was 61 8 years (range, 43-71 years). Coronary artery disease mandating additional bypasses was present in 3 patients. The bypasses were done off pump in 2 patients. Conversion to on-pump surgery was necessary in 3 of 13 patients (23%) because of hemodynamic compromise (1 patient), opening of the right ventricle (1 patient), and injury to the LAD (1 patient). Supraarterial myotomy was performed in all patients. One patient who underwent surgery with CPB developed postoperative anteroseptal myocardial infarction. Postoperative exercise testing was performed in all patients and did not reveal any persistent ischemia. Mortality was 0%. All patients were free from symptoms and had not undergone repeat interventions after an average of 51 7 months of follow-up. Conclusions: Off-pump supraarterial myotomy effectively relieves coronary obstruction but has a certain periprocedural risk as evidenced by 1 myocardial infarction, 1 right ventricular injury, and 1 LAD injury. Long-term freedom from symptoms and from reintervention favor further investigation of this surgical therapy.

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