Respiratory Pattern Research Articles

Trends in Coronary Artery Anomalies Detection by Coronary Computed Tomography Angiography (CCTA): A Real-Life Comparative Study before and during the COVID-19 Pandemic.

In the wake of the coronavirus disease 19 (COVID-19) pandemic, affecting healthcare systems globally, urgent research is needed to understand its potential repercussions on the diagnosis and management of cardiovascular disorders. This emphasises the importance of detecting coronary artery anomalies (CAAs), rare conditions that can range from benign to potentially life-threatening manifestations. We aimed to retrospectively assess the impact of the COVID-19 pandemic on the detection of various coronary anomalies using Coronary Computed Tomography Angiography (CCTA) within a regional tertiary cardiology unit in north-eastern Romania, focusing on perceived occurrence in the population under study, types, and related demographic and clinical factors. We analysed CCTA scans and investigated the trends in CAA detection among cardiology patients over a decade. We compared pre-COVID-19 and pandemic-era data to assess the impact of healthcare utilisation, patient behaviour, and diagnostic approaches on anomaly detection. Our analysis revealed a higher detection rate of CAAs during the pandemic (3.9% versus 2.2%), possibly highlighting differences in patient clinical profile and addressability changes presentation compared to the previous period. Origination and course anomalies, often linked to severe symptoms, were significantly higher pre-COVID-19 (64.1% versus 51.3%). Conversely, intrinsic CAAs, typically asymptomatic or manifesting later in life, notably increased during the pandemic (49.0% versus 61.4%; p = 0.020). Our study underscores a significant rise in CAA detection during the COVID-19 era, potentially linked to changes in cardiovascular and respiratory clinical patterns, with advanced imaging modalities like CCTA offering accuracy in identification.

Changes in respiratory infection trends during the COVID-19 pandemic in patients with haematologic malignancy

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has changed respiratory infection patterns globally. However, its impact on community-acquired pneumonia (CAP) in high-risk patients with haematological malignancies (HM) is uncertain. We aimed to examine how community-acquired pneumonia aetiology in patients with haematological malignancies changed during the COVID-19 pandemic.MethodsThis was a retrospective study that included 524 patients with haematological malignancies hospitalised with community-acquired pneumonia between March 2018 and February 2022. Patients who underwent bronchoscopy within 24 h of admission to identify community-acquired pneumonia aetiology were included. Data on patient characteristics, laboratory findings, and results of bronchioalveolar lavage fluid cultures and polymerase chain reaction tests were analysed and compared to identify changes and in-hospital mortality risk factors.ResultsPatients were divided into the ‘pre-COVID-19 era’ (44.5%) and ‘COVID-19 era’ (55.5%) groups. The incidence of viral community-acquired pneumonia significantly decreased in the COVID-19 era, particularly for influenza A, parainfluenza, adenovirus, and rhinovirus (pre-COVID-19 era vs. COVID-19 era: 3.0% vs. 0.3%, P = 0.036; 6.5% vs. 0.7%, P = 0.001; 5.6% vs. 1.4%, P = 0.015; and 9.5% vs. 1.7%, P < 0.001, respectively), whereas that of bacterial, fungal, and unknown community-acquired pneumonia aetiologies remain unchanged. Higher Sequential Organ Failure Assessment scores and lower platelet counts correlated with in-hospital mortality after adjusting for potential confounding factors.ConclusionsIn the COVID-19 era, the incidence of community-acquired pneumonia with viral aetiologies markedly decreased among patients with haematological malignancies, with no changes in the incidence of bacterial and fungal pneumonia. Further studies are required to evaluate the impact of COVID-19 on the prognosis of patients with haematological malignancies and community-acquired pneumonia.

Diurnal pattern and characteristic of soil respiration and net ecosystem carbon exchange in alpine meadow ecosystem on the northeastern Qinghai-Tibet Plateau

Analyzing the diurnal pattern of soil respiration is essential for understanding the potential mechanisms of carbon cycle. Additionally, long-term and high temporal frequency soil respiration observations are crucial and valuable at different time scales, particularly in alpine regions. Therefore, it is critical to conduct research on the diurnal pattern of soil respiration in areas sensitive to global warming. Here, four group (including soil respiration, heterotrophic respiration, net ecosystem carbon exchange, and net ecosystem carbon exchange under warming condition) of experiments were designed with a total 12 chambers, and data collected during growing season in 2023 (April to September) obtained by automatic observation system at hour-scale and four-parameter Gaussian equation were used to investigate the diurnal pattern of soil respiration and net ecosystem carbon exchange in alpine meadow ecosystem on the northeastern Qinghai-Tibet Plateau. The results indicated that: 1) the soil temperature was crucial factor for the variations in diurnal pattern of soil respiration and net ecosystem carbon exchange in four experiments. The response of the heterotrophic components to the diurnal variation in soil temperature induced diurnal lag between soil respiration and soil temperature, with mean lag time of 1.7 h. 2) The diurnal peak time of net ecosystem carbon exchange was 1–3 h earlier than respiration, and the diurnal variation of soil tempiration was one of the main driving forces. 3) Additionally, warming advanced the diurnal peak time of net ecosystem carbon exchange by 1.2–2 h through explaining the parameters of the Gaussian function. It also promoted microbial resistance, thereby limiting the increase in soil respiration during nighttime. The study suggested that temperature varied soil microenvironment and biochemical processes in alpine meadow ecosystem, thus affecting the diurnal pattern. Indeed, this study focused solely on traditional factors, and further investigations were needed, particularly from a biotic perspective, to validate these conclusions.

How Does the Interaction of the Human Thermal Plume and Breathing Affect the Microenvironment and Macroenvironment of an Elevator Cabin?

The details of the interaction of human thermal plume and breathing activities are simulated in the current study of an unsteady turbulent flow field in an elevator cabin. Air velocity and temperature distributions of the circulation flow pattern (i.e., the macroenvironment), the breathing-scale microenvironment’s characteristics, and the thermal plume’s fate are analyzed. The current study is aimed at showing how respiratory activities such as breathing and human thermal plumes affect the flow field and respiratory contaminants dispersion pattern in a nonventilated enclosed environment (the elevator cabin). The results from three cases, i.e., breathing thermal manikins, nonbreathing thermal manikins, and isothermal breathing manikins, are contrasted to unveil better the effects of human thermal plume and breathing on the flow field, including the velocity distribution, dispersion pattern of the exhaled contaminant, the human body’s heat transfer coefficient, and the large-scale flow pattern. Results reveal that breathing inhalation increases the upward velocity of the thermal plume on the one hand, which directly affects the microenvironment and indirectly impacts the macroenvironment due to the more vigorous reflected thermal plume. On the other hand, the upward thermal plume reduces the penetration length of the exhaled jet. Breathing activities create ring vortices that connect the microenvironment and the macroenvironment. The circulation flow features a downward flow in the cabin’s center, affecting the vortex strength and contaminant dispersion pattern. Overall, the human thermal plume and human breathing make comparable contributions to the resulting elevator-cabin flow characteristics.

Warming effects on grassland soil microbial communities are amplified in cool months.

Global warming modulates soil respiration (RS) via microbial decomposition, which is seasonally dependent. Yet, the magnitude and direction of this modulation remain unclear, partly owing to the lack of knowledge on how microorganisms respond to seasonal changes. Here, we investigated the temporal dynamics of soil microbial communities over 12 consecutive months under experimental warming in a tallgrass prairie ecosystem. The interplay between warming and time altered (P < 0.05) the taxonomic and functional compositions of microbial communities. During the cool months (January to February and October to December), warming induced a soil microbiome with a higher genomic potential for carbon decomposition, community-level ribosomal RNA operon (rrn) copy numbers, and microbial metabolic quotients, suggesting that warming stimulated fast-growing microorganisms that enhanced carbon decomposition. Modeling analyses further showed that warming reduced the temperature sensitivity of microbial carbon use efficiency (CUE) by 28.7% when monthly average temperature was low, resulting in lower microbial CUE and higher heterotrophic respiration (Rh) potentials. Structural equation modeling showed that warming modulated both Rh and RS directly by altering soil temperature and indirectly by influencing microbial community traits, soil moisture, nitrate content, soil pH, and gross primary productivity. The modulation of Rh by warming was more pronounced in cooler months compared to warmer ones. Together, our findings reveal distinct warming-induced effects on microbial functional traits in cool months, challenging the norm of soil sampling only in the peak growing season, and advancing our mechanistic understanding of the seasonal pattern of RS and Rh sensitivity to warming.

Is sleep bruxism in obstructive sleep apnea only an oral health related problem?

BackgroundThe etiology of sleep bruxism in obstructive sleep apnea (OSA) patients is not yet fully clarified. This prospective clinical study aimed to investigate the connection between probable sleep bruxism, electromyographic muscle tone, and respiratory sleep patterns recorded during polysomnography.Methods106 patients with OSA (74 males, 31 females, mean age: 56.1 ± 11.4 years) were divided into two groups (sleep bruxism: SB; no sleep bruxism: NSB). Probable SB were based on the AASM criteria: self-report of clenching/grinding, orofacial symptoms upon awakening, abnormal tooth wear and hypertrophy of the masseter muscle. Both groups underwent clinical examination for painful muscle symptoms aligned with Temporomandibular Disorders Diagnostic Criteria (DC/TMD), such as myalgia, myofascial pain, and headache attributed to temporomandibular disorder. Additionally, non-complaint positive muscle palpation and orofacial-related limitations (Jaw Functional Limited Scale-20: JFLS-20) were assessed. A one-night polysomnography with electromyographic masseter muscle tone (EMG) measurement was performed. Descriptive data, inter-group comparisons and multivariate logistic regression were calculated.ResultsOSA patients had a 37.1% prevalence of SB. EMG muscle tone (N1-N3, REM; P = 0.001) and the number of hypopneas (P = 0.042) were significantly higher in the sleep bruxism group. While measures like apnea–hypopnea-index (AHI), respiratory-disturbance-index (RDI), apnea index (AI), hypopnea-index (HI), number of arousals, and heart rate (1/min) were elevated in sleep bruxers, the differences were not statistically significant. There was no difference in sleep efficiency (SE; P = 0.403). Non-complaint masseter muscle palpation (61.5%; P = 0.015) and myalgia (41%; P = 0.010) were significant higher in SB patients. Multivariate logistic regression showed a significant contribution of EMG muscle tone and JFLS-20 to bruxism risk.ConclusionIncreased EMG muscle tone and orofacial limitations can predict sleep bruxism in OSA patients. Besides, SB patients suffer more from sleep disorder breathing. Thus, sleep bruxism seems to be not only an oral health related problem in obstructive apnea. Consequently, interdisciplinary interventions are crucial for effectively treating these patients.Trial registrationThe study was approved by the Ethics Committee of Philipps-University Marburg (reg. no. 13/22—2022) and registered at the “German Clinical Trial Register, DRKS” (DRKS0002959).

Respiration-triggered olfactory stimulation reduces obstructive sleep apnea severity: A prospective pilot study.

Obstructive sleep apnea is a prevalent sleep-disordered breathing condition characterized by repetitive reduction in breathing during sleep. The current care standard for obstructive sleep apnea is continuous positive air pressure devices, often suffering from low tolerance due to limited adherence. Capitalizing on the unique neurocircuitry of olfactory perception and its retained function during sleep, we conducted a pilot study to test transient, respiration-based olfactory stimulation as a treatment for obstructive sleep apnea markers. Thirty-two patients with obstructive sleep apnea (apnea-hypopnea index ≥ 15 events per hr) underwent two polysomnography sessions, "Odour" and "Control", in random order. In "Odour" nights, patients were presented with transient respiratory-based olfactory stimulation delivered via a computer-controlled commercial olfactometer (Scentific). The olfactometer, equipped with a wireless monitoring, analysed respiratory patterns and presented odour upon detection of respiratory events. No odours were presented in "Control" nights. Following exclusions, 17 patients entered the analysis (four women, 47.4 (10.5) years, body mass index: 29.4 (6.3) kg m-2). We observed that olfactory stimulation during sleep reduced the apnea-hypopnea index ("Odour": 17.2 (20.9), "Control": 28.2 (18.6), z = -3.337, p = 0.000846, BF10 [Bayesian Factor 10]= 57.9), reflecting an average decrease of 31.3% in the number of events. Relatedly, stimulation reduced the oxygen desaturation index by 26.9% ("Odour": 12.5 (15.8), "Control": 25.7 (25.9), z = -3.337, p = 0.000846, BF10 = 9.522). This effect was not linked to the severity of baseline obstructive sleep apnea markers (ρ = -0.042, p = 0.87). Olfactory stimulation did not arouse from sleep or affect sleep structure, measured as time per sleep stage (F1,16 = 0.088, p = 0.77). In conclusion, olfactory stimulation during sleep was effective in reducing the severity of obstructive sleep apnea markers without inducing arousals, and may provide a novel treatment for obstructive sleep apnea, prompting continued research.

Detection and classification of human respiration under building debris model using VHF/UHF waves

Detecting live humans in buildings that have collapsed due to disasters and identifying their condition of health is of great importance for search and rescue operations. Although various methods have been used for this purpose, there are still critical challenges to ensure accurate and rapid life-saving operations. Immediate detection of the presence of living humans under debris combined with the assessment of their vital signs is a crucial factor. This research endeavors to introduce a previously unexplored method: the use of artificial neural network-based techniques to detect human respiration under building debris by generating novel simulation-derived electromagnetic data. To achieve this, a realistic three-dimensional debris model was integrated into an electromagnetic simulation program and complemented by a phantom simulating anterior–posterior body movements indicative of respiration. Measurements of magnitude and phase between 150 and 650 MHz were performed under different conditions. Using surrogate models based on artificial neural networks, noise with different signal-to-noise ratios within the selected frequencies was introduced. These models were used to perform two different steps. Firstly, the presence of respiration of living humans trapped under debris was successfully detected with a success rate of 99.97%. Secondly, the difficult task of classifying the respiration patterns of the human was accomplished with an impressive accuracy of 99.69%, providing a solid basis for proof of concept.

Study of gas exchange under different modes of ventilation in yoga breathing exercises

Yoga breathing exercises that develop the ability to voluntarily regulate the minute volume of respiration (MV) and maintain the state of hypoventilation, hypoxia and hypercapnia, can be considered as a way of hypoxic-hypercapnic training, potentially capable of influencing cerebral circulation and neuroprotective factors. However, at the moment, individual anthropometric features that affect the ability to develop a hypoventilation mode of breathing have not been studied, and methodological criteria for training have not been developed.Methods: The study involved 44 people (32 men and 12 women) who regularly practice yoga breathing techniques with a voluntary decrease in respiratory rate using maximum tidal volume (TV). Free breathing was recorded for 2 minutes, then each subject performed the respiratory hypoventilation pattern available to him or her (minimum RR values with maximum TV, inhalation and exhalation were of equal duration). The following parameters of external respiration were determined: respiratory rate (RR), minute ventilation (MV), tidal volume (TV), partial pressure of CO2 in the exhaled air at the end of exhalation (PetCO2 ), percentage of O2 in the exhaled air (FeO2) and hemoglobin saturation (SpO2 ).Results: Compared to breathing at rest (MV = M±SD 8.51 ± 2.57 (95% CI 7.72–9.29) l/min; PetCO2 = M±SD 36.98 ± 3.71 (95% CI 35.85–38.11) mm Hg), the mode with RR = 3 times/min (inspiration and expiration for 10 s), n = 44, leads to an increase in MV up to M±SD 12.02 ± 3.42 (95% CI 10.98–13.06) l/min (p &lt; 0.001) and a decrease of CO2 : PetCO2 = M±SD 33.99 ± 3.59 (95% CI 32.90–35.08) mm Hg (p &lt; 0.001) — that is, to development of alveolar hypocapnia. The mode with RR = 1.5 times/min (inhalation and exhalation for 20 s), n = 44, demonstrates a decrease in MV to M±SD 5.95 ± 1.59 (95% CI 5.46–6.43) l/min (p &lt; 0.001) and growth of PetCO2 up to M±SD 41.19 ± 3.71 (95% CI 40.06–42.32) mm Hg (p &lt; 0.001). The mode with RR = 1 time/min (inspiration and exhalation for 30 s), n = 24: with a decrease in RR to 1 time/min, a decrease in MV was observed to M±SD 4.22 ± 0.92 (95% CI 3.83–4.61) l / min (p &lt; 0.001) and an increase in PetCO2 up to M±SD 44.05 ± 3.05 (95% CI 42.76–45.33) mm Hg (p &lt; 0.001). The breathing pattern with RR = 1 r/min is accompanied by a statistically significant decrease in MV compared to rest, as well as an increase in PetCO2 and a decrease in FeO2 , that is, it is hypoventilation. We have proposed a ventilation coefficient (Qvent), which is the ratio MV/VC, which allows us to judge at what values of MV an individual reaches a state of hypoventilation. It was previously shown in this sample that the breathing exercise becomes hypoventilation when Qvent values are equal to or less than 1. With Qvent in the range from 1 to 2, the ventilation mode is within normal values, and when Qvent is more than 2, hyperventilation occurs.Conclusion: when performing yoga breathing exercises, variations in MV are observed both in the direction of hyperventilation and in the direction of hypoventilation with corresponding shifts in gas exchange (hypocapnia with hyperventilation, hypercapnia with hypoventilation). The MV values at which an individual reaches hypoventilation vary from person to person and can be predicted using the ventilation coefficient (Qvent).

Variation in metabolic rate during low tide aerial exposure in the Asian shore crab Hemigrapsus sanguineus

Intertidal animals deal with physical gradients daily that create stressful conditions across the shore. These physical gradients influence the physiological performance of organisms, requiring responses that may differ with height on the shore. We examined the respiratory response to aerial exposure in the invasive Asian shore crab Hemigrapsus sanguineus during periods of low tide emersion using two field experiments. The first experiment simultaneously measured respiration of individuals collected from different heights on the shore, which had therefore been emersed for different lengths of time. The second experiment measured respiration of individuals collected at different times from the same tidal height. Respiration rates of crabs in both experiments increased immediately after emersion, nearly doubling by and peaking at ~ 1.5 h of aerial exposure, before decreasing again over the next 1.5 h. These results suggest that the energetic cost of low tide exposure is greatest shortly after emersion during the first half of the typical low tide period, but then decreases thereafter. These respiration patterns facilitate the broad intertidal distribution of this species on rocky shores throughout its range.

Influence of intercostal muscles contraction on sonographic evaluation of lung sliding: a physiological study on healthy subjects

ObjectivesTo investigate the following: (a) effects of intercostal muscle contraction on sonographic assessment of lung sliding and (b) inter-rater and intra-observer agreement on sonographic detection of lung sliding and lung pulse.MethodsWe used Valsalva and Muller maneuvers as experimental models in which closed glottis and clipped nose prevent air from entering the lungs, despite sustained intercostal muscles contraction. Twenty-one healthy volunteers underwent bilateral lung ultrasound during tidal breathing, apnea, hyperventilation, and Muller and Valsalva maneuvers. The same expert recorded 420 B-mode clips and 420 M-mode images, independently evaluated for the presence or absence of lung sliding and lung pulse by three raters unaware of the respiratory activity corresponding to each imaging.ResultsDuring Muller and Valsalva maneuvers, lung sliding was certainly recognized in up to 73.0% and up to 68.7% of imaging, respectively, with a slight to fair inter-rater agreement for Muller maneuver and slight to moderate for Valsalva. Lung sliding was unrecognized in up to 42.0% of tidal breathing imaging, and up to 12.5% of hyperventilation imaging, with a slight to fair inter-rater agreement for both. During apnea, interpretation errors for sliding were irrelevant and inter-rater agreement moderate to perfect. Even if intra-observer agreement varied among raters and throughout respiratory patterns, we found it to be higher than inter-rater reliability.ConclusionsIntercostal muscles contraction produces sonographic artifacts that may simulate lung sliding. Clinical studies are needed to confirm this hypothesis. We found slight to moderate inter-rater agreement and globally moderate to almost perfect intra-observer agreement for lung sliding and lung pulse.Trial registrationClinicalTrials.gov registration number.NCT 02386696.

102 Circadian patterns of behavior, respiration, rectal temperature, saliva melatonin, cytokine concentrations, and milk immune cells are altered by cooling heat-stressed lactating sows

Abstract Lactating sows are particularly vulnerable to heat stress (HS) due to the increased metabolism from milk production. A greater understanding of HS response could assist in mitigating its detrimental effects on animal production. Two core circadian clock genes were pinpointed in a recent genome study as potential mediators of HS response, indicating the possible alteration of circadian clocks by HS exposure. This study aimed to assess how cooling of lactating sows under natural heat stress conditions in the summer influenced circadian patterns of respiration rate (RR), rectal temperature (RT), behaviors, salivary concentration of cortisol and melatonin, milk cell populations and relative abundance of multiple cytokines in saliva. Lactating sows of mixed parities were divided into two treatment groups: treated with electronic cooling pad (C; n=9) and heat-stressed control (H; n=9). Experiments were conducted during two 48 h periods of increased environmental temperatures from summer heatwaves. During the initial 48 h period, rectal temperature (RT) was monitored every 60 min, rectal temperature (RT) every 30 min, and behaviors of eating, standing, sitting, laying, sleeping, drinking, and nursing every 5 min. Morning milk samples were collected following the completion of the first phase and utilized to categorize and count somatic cells. The second trial was approximately 1 wk later, and during this period saliva samples were collected every 4 h over the 48-h period. Results were analyzed for significant effect of treatments and interaction using periodic regression while circadian patterns were further detected by incorporating a Fourier series model utilizing sine-cosine variables that denote a fit and/or shift in circadian pattern. The analysis revealed that cooling decreased RT and RR while also modifying circadian patterns (P &amp;lt; 0.05). Cooling had no impact on the percentage of time spent in any activity over the 48-h period (P &amp;gt; 0.05). Nevertheless, the daily patterns of eating, standing, and sitting were different between the treatments (P &amp;lt; 0.05). A shift in eating time to later in the day in H sows relative to C sows related to a second rise in RT during the dark phase of the light-dark cycle (P &amp;lt; 0.05). Saliva melatonin concentrations were increased in C sows and circadian pattern altered relative to H (P &amp;lt; 0.05), but there was no effect on salivary cortisol concentrations (P &amp;gt; 0.05). Cooling reduced milk lymphocytes (P &amp;lt; 0.05) and influenced diurnal pattern of saliva cytokines including interleukins (IL) IL-1 alpha, IL-1 beta, IL-10, and IL-15 and transforming growth factor-beta 1. In conclusion, the cooling of heat-stressed sows altered the circadian patterns of physiology, behavior and melatonin, suggesting the need for additional research to investigate whether circadian disruption contributes to reduced production efficiency observed in HS animals.

Relationship between commonly defined metabolic health phenotypes and obesity with lung function in a working population: A cross-sectional study

BackgroundFour phenotypes relate metabolism and obesity: metabolically healthy (MHO) and unhealthy (MUO) people with obesity and metabolically healthy (MHNO) and unhealthy (MUNO) people without obesity. No studies have addressed the association between these categories and lung function in the working population. ObjectivesThe aim was to determine the relationship of phenotypes to lung ageing as measured by lung age and its relationship to lung dysfunction. MethodsA descriptive cross-sectional study was conducted in a working population. The outcome variable was lung function assessed by lung age. The four phenotypes of obesity and metabolic health (MHNO, MHO, MUO and MUNO) were determined using NCEP-ATP III criteria. Lung dysfunctions were classified into restrictive, obstructive, and mixed patterns. ResultsThe mean age of the participants was 43.7 years, ranging from 18 to 67 years. Of the 1860 workers, 51.3 % were women. The prevalences found were 71.4 %, 12 %, 10.6 % and 6 % for MHNO, MUO, MHO, and MUNO, respectively. MHO (β = 0.66; p = 0.591) was not associated with increased lung ageing compared with MHNO, but MUO (β = 7.1; p < 0.001) and MUNO (β = 6.6; p < 0.001) were. Concerning pulmonary dysfunctions, MUNO (OR = 1.93; p < 0.001) and MUO (OR = 2.91; p < 0.001) were found to be related to the presence of a restrictive pattern, and MUNO (OR = 2.40; p = 0.028) to the mixed pattern. ConclusionThe results show that metabolic abnormalities, not obesity, are responsible for premature lung ageing and, therefore, lung function decline. In our study, having obesity without metabolic abnormality was not significantly associated with the presence of dysfunctional respiratory patterns.

Root Respiration–Trait Relationships Are Influenced by Leaf Habit in Tropical Plants

Root respiration is a critical physiological trait that significantly influences root system activity. Recent studies have associated root respiration with the economic functioning of roots; however, research on root respiration in tropical plants remains limited. This study examined the fine root respiration and the relationship between root respiration and root chemical and morphological traits in 16 tropical plant species, including both evergreen and deciduous species. Findings revealed that deciduous species exhibited higher root respiration compared to evergreen species. Root respiration positively correlated with root nitrogen concentration and specific root length and correlated negatively with root diameter and root tissue density across all species. The root respiration patterns in evergreen species aligned with those seen in all tree species, while deciduous species showed a distinct negative correlation with root tissue density and no significant correlations with other root traits. Principal component analysis revealed that the patterns of root variation in both evergreen and deciduous trees were multidimensional, with deciduous trees exhibiting acquisitive traits and evergreen trees displaying conservative traits. Random forest and multiple regression analysis showed that specific root length exerted the most significant influence on root respiration in both evergreen and deciduous trees. These findings are ecologically significant, enhancing our understanding of root respiration in tropical plants and its impact on ecosystem functions. They contribute valuable insights and support the conservation and management of tropical vegetation.

Sex Differences In The Phenotype Of Sleep-Disordered Breathing In C57BL/6J Mice

Sex differences in sleep-disordered breathing (SDB) are widely recognized. SDB is more prevalent in men, but women appear to exhibit more symptoms at lower levels of SDB severity, including insomnia symptoms. Mechanisms underlying sex differences in SDB are unknown. In this study, we compared the sleep architecture and breathing patterns during sleep between male and female mice and examined the effects of ovariectomy on SDB. We hypothesized that female and male mice differed in sleep and SDB, which are related to differences in carbon dioxide (CO2) chemosensitivity between sexes. Adult male (n=9) and female (n=10) C57BL/6J mice underwent full-polysomnography inside a whole-body plethysmography chamber. Arousals from sleep and apneas were manually scored. Breathing variability was assessed with Poincaré plots of minute ventilation. Hypercapnic ventilatory response (HCVR) was assessed during wakefulness and NREM sleep by acute administration of 8% CO2. In female mice, we performed bilateral ovariectomy and repeated sleep studies after 14 days. We found that arousal index was 55% increased in females compared to males, but sleep fragmentation was mainly attributed to spontaneous arousals in both groups. Surprisingly, apnea severity was significantly increased in female mice compared to males (32.4±6.7 vs 11.8±4.5, P=0.001). Breathing instability was also increased in females. HCVR was positively correlated with apnea index (r=0.55, P=0.05) and was significantly augmented in females compared to males. Ovariectomy did not affect sleep fragmentation, but attenuated CO2 sensitivity and improved breathing stability during sleep. Our results have suggested different SDB phenotypes between male and female C57BL/6J mice. SDB in female mice is associated with a hyperarousal state and increased HCVR compared to males. An exacerbated CO2 responsiveness related to ovarian hormones in females is an important determinant of differences in SDB severity and respiratory patterns between male and female sex. American Heart Association Postdoctoral Fellowship Award 828142 (to L.J.K.), NHLBI grant 2R01 HL133100-05, NIH R01 HL128970, and R01 HL13892 (to V.Y.P.), 1K23HL155730 and American Academy of Sleep Medicine Foundation 238-BS-20 (to L.V.P.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Lumbar epidural electrical stimulation enhances respiration in mice

Spinal cord epidural electrical stimulation (EES) has emerged as a novel approach to modulate and interrogate the neural circuit(s) underlying sensorimotor functions in the past few decades. Recent studies have revealed that cervical EES can regulate respiration in both human subjects and animal models. Furthermore, coupled cervical and lumbar stimulations significantly increased the rhythmic motor outputs in both the cervical and lumbar spinal cord. We hypothesize that the lumbar and cervical coupling is underpinned by cervico-lumbar synaptic connections, and thus, EES at level of the lumbar spinal cord alone may also facilitate respiration via the cervico-lumbar circuit. In this study, we applied EES to the dorsal surface of the lumbar spinal cord between levels 1 and 6 (L1-6) in anesthetized mice. We found that rostral lumbar (L1-2) EES at a stimulation intensity of 0.5 mA elicited significantly higher respiratory frequency, tidal volume, and minute ventilation responses compared to the other lumbar levels (L3-4 and L5-6) tested at intensities ranging from 0.1-1.0 mA. The increased respiratory activity elicited by lumbar stimulation persisted even after the stimulation ceased. Using the optimal stimulation parameters that we identified, we further investigated the underlying mechanism of the lumbar EES-induced respiratory response by examining the neuronal activation patterns. Using immunostaining, we detected c-fos signals, a marker of neuronal activity, in the cervical spinal cord and brainstem after EES at L1-2 using 0.5 mA at 30Hz. This indicates that focal lumbar stimulation elicits remote neuronal activation in cervical spinal cord and brainstem, regions that contain respiration-related neural circuits. These findings suggest that lumbar EES may facilitate respiration by recruiting paraspinal respiratory circuits and potentially supra-spinal respiratory central pattern generator(s). This study provides insights into the development of novel approaches to restore normal respiratory patterns for patients with respiratory disorders, particularly spinal cord injuries. This work was supported by The Louis and Harold Price Foundation, H &amp; H Evergreen Foundation, Jonathan and Susan Dolgen Foundation, the National Institute of Drug Abuse (R01DA047637), and the National Institute of Neurological Disorders and Stroke (UH3NS119772) in the National Institutes of Health. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Respiratory Modulation of Muscle Sympathetic Nerve Activity in Type 2 Diabetes Mellitus

Dysfunctional sympathetic neural regulation is present in patients with type 2 diabetes (T2D) with augmented muscle sympathetic nerve activity (MSNA) responses to handgrip exercise, cold pressor testing, and augmented sympathetic-blood pressure transduction identified. MSNA is modulated by respiration such that it is inhibited at higher lung volumes and increased at lower lung volumes. Herein we aimed to determine whether T2D affects the respiratory modulation of MSNA. Resting MSNA (microneurography) and respiration pattern (strain-gauge pneumobelt) were measured simultaneously in 20 patients with T2D (age 49.1±7.4 years, body mass index [BMI] 31.9±4.1 kg∙m−2, mean ± SD) and 13 age- and BMI-matched, healthy controls (46.3±9.4 years; 32.1±4.6 kg∙m−2). MSNA was stratified by the phase of respiration. Further comparisons were made between low lung volume (defined as 60-100% expiration + 0-60% inspiration) and high lung volume states (60-100% inspiration + 0-60% expiration). Resting MSNA burst frequency, burst incidence and total activity were similar between T2D and controls (p=0.953, p=0.624, and p=0.884, respectively). Both groups exhibited peak MSNA in late expiration to early inspiration, whilst inhibition of MSNA occurred during late inspiration to early expiration (respiratory phase p&lt;0.001 for burst frequency, incidence and total activity), though no group x respiratory phase interaction was observed (p&gt;0.05 for all MSNA measures). When MSNA responses were compared between lung volume states, percent reduction of MSNA burst incidence from low lung volume to high lung volume was less in T2D than controls (26.1±33.9 vs 50.1±25.6%, p=0.025). Furthermore, in T2D, there was a shift in the distribution of MSNA bursts with a greater proportion of bursts occurring at high lung volumes (i.e., burst count during high lung volume divided by total burst count) compared to controls (43.8±10.5 vs. 37.8±12.5% respectively, group x volume interaction p=0.04). Notably, the normal pattern of respiratory modulation of MSNA was absent in 5 T2D patients (non-modulators), whilst this did not occur in any control participants. Non-modulators had higher systolic blood pressure compared to modulators (138.7±16.6 vs. 123.2±10.6 mmHg respectively, p=0.024), with no differences in age, BMI, HbA1c, duration of T2D, or overall MSNA parameters (all p&lt;0.05). These results suggest that whilst respiratory modulation of MSNA occurs in T2D, its effect appears blunted compared to healthy controls. Notably, the usual pattern of respiratory-sympathetic coupling is absent in some T2D patients, which may be associated with higher resting systolic blood pressure. MP is supported by the Greenlane Research and Educational Fund (21/01/4153). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

SARS-CoV-2 Decreases Neuronal Activity in Brainstem Respiratory Centers in C57BI6/J Mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also called COVID-19, targets the respiratory system, leading to symptoms such as cough, fever, and diffculty breathing. As the mechanisms behind SARS-CoV-2 infections continues to be studied, understanding of how this virus targets specific tissues becomes more apparent. Angiotensin-converting enzyme-2 (ACE2), the target of SARS-CoV infections and a functional receptor for SARS-CoV-2 invasions, is highly expressed in many tissues throughout the body, including the lungs, kidneys, and brain. Notably, our group previously reported that neurons are the main cells within the brain expressing ACE2. Accordingly, we hypothesized that neuronal infection of brainstem respiratory centers by SARS-CoV-2 could contribute to respiratory symptoms associated with COVID-19, specifically respiratory failure. C57BI6/J mice were mock infected or received SARS-CoV-2 (7.5x103 or 1.5x104) intranasally in a BSL-3 facility (University of Texas in Galveston) and were euthanized by CO2 hypoxia after 5 days post infection. The heads were harvested and immersed in formalin for 3 days before being transferred to LSU Health-NO for processing. Brains were carefully dissected out and preserved in optimal cutting temperature (OCT) before sectioning on a cryostat. Sections (30 μm) containing the retrotrapezoid nucleus (RTN) were selected as its neurons are part of the pontomedullary regions that generate the respiratory rhythm and pattern. Immunohistochemistry for c-Fos, a marker of neuronal activity, was used to assess neuronal activity in the RTN. Sections were incubated overnight with a primary monoclonal antibody (rabbit anti c-Fos, 1:1000) followed with a secondary goat antirabbit fluorescent IgG (GFP, 1:200, 1h) antibody. Sections were then mounted to slides in the dark to preserve the fluorescence and observed under the microscope. Images of neurons present in the RTN were captured and neurons were then hand counted and averaged. Neuronal activity in the RTN was decreased with the dose of SARS-CoV-2 used to infect cells in the brain. The greater the dose of SARS-CoV-2, the lower the number of c-Fos-positive neurons was detected in the RTN. Mock brains had the greatest number of neurons and brains infected with 1.5x104 SARS-CoV-2 had the lowest number of neurons in the RTN. This was demonstrated by counting neurons at 3 different intervals and taking the average. We conclude that SARS-CoV-2 targets neurons in respiratory centers, possibly contributing to impaired respiratory function in infected patients. NIH/NHLBI HL163814. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Respiration and Cough in Pompe Disease: Results from a neuromechanical computational model of the respiratory control system

Late Onset Pompe Disease (LOPD) is an incurable, rare progressive genetic disease. It is characterized by glycogen build-up, due to mutations in the gene encoding the lysosomal enzyme acid alpha glucosidase, throughout muscle and neural regions. This accumulation is associated with cell death and muscle fiber swelling, eventually leading to respiratory insuffciency and airway clearance (i.e. cough) deficiency. Impairments in effective airway clearance result from the inability to clear normal pulmonary volume. Emerging evidence indicates significant respiratory neuron dysfunction, altering pulmonary function in humans and animal models. It has been suggested that respiratory and airway clearance insuffciency observed in LOPD may be attributed to medullary motoneurons potentially associated with the respiratory and cough pattern generators (Fuller et al., 2013; DeRuisseau et al., 2009). However, the precise neural mechanisms that suppress breathing and cough are not fully understood. One possible target for LOPD respiratory insuffciencies may be reduced medullary inspiratory neuron activity within this network, which could result in decreased phrenic motoneuron output. Using a stochastic neural network simulator that consisted of discrete “integrate and fire” populations, we simulated a systematic decrease in three medullary inspiratory neuron populations: inspiratory driver (I-Driver), inspiratory decrementing (I-Dec), or inspiratory augmenting (I-Aug) neurons. We simulated breathing and three cough trials. By targeting these populations, we expected global decreased neural bursts, suppressed inspiratory motor drive, and/or suppressed expiratory motoneuron output. Simulations indicated that when the I-Dec motoneuron population decreased by 25%, it resulted in apnea and abolished cough. Reducing the I-Aug motoneuron population by 20% resulted in longer inspiratory phase durations (TI) and a decreased respiratory rate. During cough, there was a decrease in the duration and amplitudes of the expiratory motoneuronal activity associated with decreased cough receptor and pulmonary stretch receptor afferent feedback. When the I-Driver motoneuron population was reduced by 25%, TI decreased and I amplitude increased during respiration. During cough, lumbar and phrenic motoneuron discharge duration and amplitude decreased. These results are consistent with previously reported in vivo data. Overall, our simulation data support the plausibility of glycogen storage dysfunction impairing medullary neuronal and premotoneuronal excitability within the inspiratory network. Our results also suggest that some neurons may be more sensitive to glycogen storage than others within the brainstem inspiratory network. Supported by NHLBI L30HL165496, NIH T32 HL 134621 and 3OT2OD023854. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex-Specific Mitochondrial Bioenergetics Differences in Heart and Kidney Cortex

Rationale: Mitochondrial bioenergetics of different tissues have been studied widely, but their sex-specific differences have not been systematically studied. The goal of this study was therefore to investigate the sex-specific differences in mitochondrial respiration (oxygen consumption rate; OCR) and membrane potential (Δψ) in the heart and kidney cortex and to explore underlying mechanisms responsible for any observed differences. Methods: Mitochondria were isolated from adult male and female Sprague-Dawley rat heart and kidney cortex and were used to study their bioenergetics responses. Three different substrate combinations, namely, pyruvate+malate (PM), glutamate+malate (GM), and succinate in the presence of complex I inhibitor rotenone (SR) were used. This was followed by two different ADP addition protocols to determine how different substrates influence mitochondrial OCR and Δψ to ADP perturbations during oxidative phosphorylation (OxPhos) in male and female heart and kidney cortex. In one, a single saturated dose of ADP, while in the other, sequentially increasing doses of ADP were added to mitochondria in the presence of different substrates. Mitochondrial OCR was measured using a dual chamber Oroboros Oxygraph-2k Instrument and Δψ was measured using a spectrofluorometer and rhodamine-123 dye. From these measurements, OCR and Δψ alterations under different respiratory states and as functions of added ADP concentration were determined for different substrates and for both male and female rats. Results: Male and female mitochondria exhibited distinct respiratory patterns in the kidney cortex and heart with different substrates. In the kidney cortex, male mitochondria showed significantly higher OCR than female mitochondria when fueled with PM or SR. However, no significant sex differences in the OCR were observed when GM were used as substrates. In contrast, heart mitochondria exhibited negligible sex differences in the OCR for PM and SR, but significant differences emerged with GM, where female mitochondria displayed higher OCR than their male counterparts. Interestingly, sex-specific variations of Δψ in ADP-stimulated respiration were not apparent for either tissue or substrate when a single saturated dose of ADP was used. Instead, a trend similar to the OCR emerged when ADP was administered in gradually increasing concentrations. Conclusion: Heart and kidney cortex mitochondrial Δψ for males and females did not differ conclusively with the two ADP addition protocols. However, there were significant differences in the OCR of mitochondria from the heart and kidney cortex of males and females, depending on the respiratory substrate utilized. Males were found to have enhanced OCR in the kidney cortex, whereas females exhibited higher OCR in the heart. These observed sex-specific differences in the OCR could be attributed to differential regulation of mitochondrial metabolic pathways by respiratory substrates and sex hormones. NIH R01-HL151587. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.