Nonobstructive (i.e., central) sleep apnea is a major cause of sleep-disordered breathing in patients with stable congestive heart failure (CHF). Although central sleep apnea (CSA) is prevalent in this population, occurring in 40-50% of patients, its pathogenesis is poorly understood. Dynamic loop gain and delay of the chemoreflex response to CO(2) was measured during wakefulness in CHF patients with and without CSA by use of a pseudorandom binary CO(2) stimulus method. Use of a hyperoxic background minimized responses derived from peripheral chemoreceptors. The closed-loop and open-loop gain, estimated from the impulse response, was three times greater in patients with nocturnal CSA (n = 9) than in non-CSA patients (n = 9). Loop dynamics, estimated by the 95% response duration time, did not differ between the two groups of patients. We speculate that an increase in dynamic gain of the central chemoreflex response to CO(2) contributes to the genesis of CSA in patients with CHF.
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http://dx.doi.org/10.1152/jappl.2001.91.1.408 | DOI Listing |
Glob Chang Biol
January 2025
Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
Stomata control plant water loss and photosynthetic carbon gain. Developing more generalized and accurate stomatal models is essential for earth system models and predicting responses under novel environmental conditions associated with global change. Plant optimality theories offer one promising approach, but most such theories assume that stomatal conductance maximizes photosynthetic net carbon assimilation subject to some cost or constraint of water.
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January 2025
Faculty of Agricultural, Environmental and Food Sciences, Free University of Bolzano, Bolzano, Italy.
The ecophysiological and ecohydrological impacts of climate change and progressively increasing atmospheric carbon dioxide (CO) concentration on agroecosystems are not well understood compared to the forest ecosystems. In this study, we utilized the presence of old apple and pear trees in the alpine valleys of Northern Italy (maintained for cultural heritage purposes) to investigate climate-scale physiological responses. We developed long-term tree-ring stable isotopic records (δC and δO) from apple (1976-2021) and pear trees (1943-2021).
View Article and Find Full Text PDFPlants (Basel)
January 2025
State Key Laboratory of Efficient Utilization of Agricultural Water Resources, Beijing 100083, China.
Plants respond to environmental changes by altering the anatomical structure of the xylem and its hydraulic properties. While numerous studies have explored the effects of individual environmental factors on crops, the combined interactions of these factors remain underexplored. As climate change intensifies, the occurrence of salt stress is becoming more frequent, alongside a rise in atmospheric CO concentration.
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January 2025
Department of Botany, Aligarh Muslim University, Aligarh 202002, India.
Plants face a range of environmental stresses, such as heat and drought, that significantly reduce their growth, development, and yield. Plants have developed complex signaling networks to regulate physiological processes and improve their ability to withstand stress. The key regulators of plant stress responses include polyamines (PAs) and gaseous signaling molecules (GSM), such as hydrogen sulfide (HS), nitric oxide (NO), methane (CH), carbon monoxide (CO), carbon dioxide (CO), and ethylene (ET).
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Potato has great nutritional and economic importance in agriculture. However, represents a significant risk, reducing the yield and quality of potato production. Flesh-colored potato (FCP) extracts show in vitro inhibitory effects against , although environmental factors may reduce their stability.
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