Nine healthy female subjects were studied when exposed to the natural light-dark cycle, but living for 17 "days" on a 27h day (9h sleep, 18h wake). Since the circadian endogenous oscillator cannot entrain to this imposed period, forced desynchronization between the sleep/activity cycle and the endogenous circadian temperature rhythm took place. This enabled the effects of activity on core temperature to be assessed at different endogenous circadian phases and at different stages of the sleep/activity cycle. Rectal temperature was measured at 6-minute intervals, and the activity of the nondominant wrist was summed at 1-minute intervals. Each waking span was divided into overlapping 3h sections, and each section was submitted to linear regression analysis between the rectal temperatures and the total activity in the previous 30 minutes. From this analysis were obtained the gradient (of the change in rectal temperature produced by a unit change in activity) and the intercept (the rectal temperature predicted when activity was zero). The gradients were subjected to a two-factor analysis of variance (ANOVA) (circadian phase/ time awake). There was no significant effect of time awake, but circadian phase was highly significant statistically. Post hoc tests (Newman-Keuls) indicated that gradients around the temperature peak were significantly less than those around its trough. The intercepts formed a sinusoid that, for the group, showed a mesor (+/-SE) of 36.97 (+/-0.12) and amplitude (95% confidence interval) of 0.22 degrees C (0.12 degrees C, 0.32 degrees C). We conclude that this is a further method for removing masking effects from circadian temperature rhythm data in order to assess its endogenous component, a method that can be used when subjects are able to live normally. We suggest also that the decreased effect of activity on temperature when the endogenous circadian rhythm and activity are at their peak will reduce the possibility of hyperthermia.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.3109/07420529909116863 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Increased robustness and adaptation to simultaneous temperature and elevated extracellular potassium in the pyloric rhythm of the crab, .
J Neurophysiol
February 2025
Biology Department and Volen Center, MS 013, Brandeis University, Waltham, Massachusetts, United States.
Animals must deal with numerous perturbations, oftentimes concurrently. In this study, we examine the effects of two perturbations, high extracellular potassium and elevated temperature, on the resilience of the pyloric rhythm of the crab, . At control temperatures (11°C), high potassium saline (2.
View Article and Find Full Text PDFAssociation between Air Pollutants and Out-of-Hospital Cardiac Arrest: A 5-Year Time Series Analysis.
Eur Heart J Acute Cardiovasc Care
January 2025
Department of Emergency Medicine, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen 518035, Guangdong, China.
Background: We aimed to analyze the yet unclear correlation between air pollutant concentrations (AP) and out-of-hospital cardiac arrest (OHCA) in Shenzhen, China.
Methods: A 5-year time series analysis of all OHCA events reported to the Shenzhen Emergency Center was conducted. Quasi-Poisson regression, controlling for meteorological variables (daily mean relative temperature and humidity) with multivariable fractional polynomial and using Fourier series to adjust for long-term trends and account for periodic patterns, was used to assess the association among particulate matter of 2.
Seasonal plasticity in daily timing of flight activity in is driven by temperature modulation of dawn entrainment.
Philos Trans R Soc Lond B Biol Sci
January 2025
Chronobiology Section, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK.
The Asian malaria vector is invading Africa, requiring it to adapt to novel climates and ecosystems. In part, this may be facilitated by 's poorly understood seasonal behavioural plasticity in flight timing, leading to earlier biting activity in cold Asian winters and later biting times in the warm summer. Changes in behavioural timing could be directly imposed by seasonal variation in ambient light and temperature levels or result from altered entrainment of intrinsically expressed circadian rhythms by these factors.
View Article and Find Full Text PDFCircadian gating: concepts, processes, and opportunities.
Philos Trans R Soc Lond B Biol Sci
January 2025
John Innes Centre, Norwich Research Park, Norwich, UK.
Circadian clocks provide a biological measure of time that coordinates metabolism, physiology and behaviour with 24 h cycles in the environment. Circadian systems have a variety of characteristic properties, such as entrainment to environmental cues, a self-sustaining rhythm of about 24 h and temperature compensation of the circadian rhythm. In this perspective, we discuss the process of circadian gating, which refers to the restriction of a biological event to particular times of day by the circadian clock.
View Article and Find Full Text PDFImmune regulation of host energy metabolism and periodicity of malaria parasites.
Philos Trans R Soc Lond B Biol Sci
January 2025
Laboratory of Immunopathology - Instituto René Rachou, Fundação Oswaldo Cruz - Minas, Belo Horizonte 30190-002, Brazil.
The synchronization of parasites as they replicate within red blood cells of their vertebrate host remains largely unexplored. Understanding this synchronization could reveal how parasites optimize their lifecycle to maximize transmission, evade the immune response and maximize energy acquisition. Rhythmic replication fulfils some criteria of an endogenous oscillator with time of day cues potentially provided by temperature, oxygen levels, hormones and/or nutrient availability.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!