Frontiers in Physiology最新文献

Introduction: Ischemic stroke in patients with a systemic tumor disease or cancer not in remission (active tumors) is less well understood. Some aspects of such paraneoplastic strokes remind on a generalized cerebrovascular disorder. We hypothesized that cerebrovascular regulation in active tumor patients with a stroke is different from other patients with stroke who have no active tumor disease.

Methods: Within the first 72 h after the acute ischemic stroke, cerebral blood flow regulation was analyzed by means of transfer function analysis between middle cerebral artery blood flow velocity and blood pressure with estimation of coherence, gain and phase in the very low (0.02-0.07 Hz), low (0.07-0.20 Hz) and high frequencies (0.20-0.5 Hz) in four stroke groups: active tumors, inactive tumors (untreated and in remission), hypertensive lacunar stroke (LS), and non-hypertensive embolic stroke (NHES).

Results: The 4 groups did not differ regarding age, sex distribution, and brain infarct size on magnet resonance imaging Between the four stroke groups, phase was not different in any frequency range in both hemispheres. Gain was highest (either significant or by trend) in the active tumor group in the HF range in comparison to all other stroke subgroups, it was also higher in the LF range in the stroke affected hemisphere when compared to the LS group. The HF gain findings were independent of end-tidal CO2 levels but exhibited some dependency of coherence.

Discussion: The high gain can be interpreted as a generalized high vascular resistance. The cerebrovascular regulation in active tumor patients seems to exhibit some analogy to hypertensive patients with lacunar stroke.

Clinical trial registration: clinicaltrials.gov, identifier NCT04611672.

During pregnancy, marked changes in vasculature occur. The placenta is developed, and uteroplacental and fetoplacental circulations are established. These processes may be negatively affected by genetic anomalies, maternal environment (i.e., obesity or diabetes), and environmental conditions such as pollutants and hypoxia. Chronic hypoxia has detrimental effects on the vascular adaptations to pregnancy and fetal growth. The typical pregnancy-dependent rise in uterine blood flow by vascular remodeling and vasodilation of maternal uterine arteries is reduced, leading to increases in vascular tone. These maladaptations may lead to complications such as fetal growth restriction (FGR) and preeclampsia. In this review, the effect of hypoxia on uteroplacental and fetoplacental circulation and its impact on pregnancy outcomes in humans and animal models are discussed. Evidence is provided for several mechanisms that affect pregnancy through hypoxia-induced alterations. Future directions to fill gaps in knowledge and develop therapeutic strategies to prevent or alleviate hypoxia-related pregnancy complications, such as FGR and preeclampsia, are suggested.

Objective: The primary aim of this study was to compare the immediate effect of contrast compression therapy with the use of Game Ready (GRT) on hyperaemic reactions in the upper limb on the application and contralateral sides, specifically in the context of mixed martial arts (MMA) athletes.

Design: In this experimental, single-blind, randomized crossover study, we recruited 30 male volunteers training in MMA (mean age: 28.33 ± 3.79 years, BMI: 25.25 ± 3.06, training experience: 9.93 ± 3.83). They were randomly assigned to the experimental (n = 15) or control (sham) group (n = 15). The experimental group underwent a 10-minute Game Ready Therapy (GRT) session, while the control group GRS underwent a sham therapy session. After a 2-week break, a cross-over change of therapy in the groups was performed, ensuring a comprehensive evaluation of the contrast compression therapy's perfusion effects in 30 participants. Main outcome measures: Hyperemic reaction was measured: rest flow (RF - [non-referent unit]); therapeutic flow (TF- [min]), i.e., the average flow recorded during GR or sham therapy: time of recovery (TR - [min]), i.e., the time for perfusion to return to the resting value after the intervention. Measurements were performed on the ipsilateral and contralateral sides.

Results: The mean perfusion during therapy was significantly higher in GRT compared to GRS (24.70 ± 1.45 vs. 12.60 ± 1.37; p < 0.001; ES = 5.7 [large]; △ = 12.10 > MDC). The time from cessation of contrast therapy to the return of blood flow to resting values showed significantly higher values in GRT compared to GRS (3.07 ± 0.45 vs. 16.80 ± 0.91; p < 0.001; ES = 16.27 [large]). No statistically significant difference was noted between the mean resting perfusion value (RF) and the mean perfusion value during therapy (TF) in the contralateral limb (7.74 ± 0.89 vs. 7.66 ± 0.89; p = 0.284; ES = 0.20 [negligible]; △ = 0.09 < MDC.

Conclusion: This study suggests that compression contrast therapy on the ipsilateral side positively affects the intensification of the hyperaemic reaction. However, no statistically significant hyperaemic responses were observed on the contralateral side.

In this quasi-experimental before-after trial, we investigated the effects of a high-intensity, low-repetition inspiratory muscle training (HI-LRMT) protocol on respiratory muscle strength in instrumental musicians. In addition, was to estimate the prevalence of "non-responders" (NRs) in terms of muscle force after intervention. Healthy musicians (n = 48) were divided into 2 groups: HI-LRMT (n = 33) and a control group that did not train (CG, n = 15). The intervention training was a high-intensity, low-repetition inspiratory muscle training program using the PowerBreathe^® threshold load pressure device, 2 daily sessions of 30 repetitions per session, with a minimum frequency of 5 days per week, for 12 weeks, 5 min per session. The primary outcome measures were maximal inspiratory pressure and expiratory pressure. Change in PImax over 12 weeks for HI-LRMT vs. control was 30.9 (95% CI 25.5-38.3), with the large effect, confirming worthwhile benefits (ηp ² = 0.61). There were significant changes in PEmax 37.3 (95% CI 19.3-48.1), with a large effect size (ηp ² = 0.33). A third of the participants did not demonstrate improvements in terms of muscle force in instrumental musicians. In conclusion, a 12-week high-intensity, low-repetition inspiratory muscle training program using the PowerBreathe^® threshold load pressure device, improved inspiratory and expiratory muscle strength in instrumental musicians.

Insight into human physiology is key to maintaining diver safety in underwater operational environments. Numerous hazardous physiological phenomena can occur during the descent, the time at depth, the ascent, and the hours after a dive that can have enduring consequences. While safety measures and strict adherence to dive protocols make these events uncommon, diving disorders still occur, often with insufficient understanding of the factors that triggered the event. This review first examines the most common diving disorders and their incidence rates across recreational and US military dive activities. The review then identifies physiological biomarkers (e.g., heart rate, heart rate variability, blood pressure, respiration rate, temperature, oxygen saturation) that may provide a holistic view of the diver's current physiological state and potentially detect the most concerning diving disorders (e.g., decompression illnesses, gas mixture-related disorders, barotraumas, and environment exposure). Although considerable research is still needed to verify the use of these biometrics in the diving environment, the research described in this review presents a promising path to developing a system that can detect pending diving disorders and provide divers and other necessary parties with an early warning before mishaps occur.

The Lim Kinase (LIMK) family of serine/threonine kinases is comprised of LIMK1 and LIMK2, which are central regulators of cytoskeletal dynamics via their well-characterized roles in promoting actin polymerization and destabilizing the cellular microtubular network. The LIMKs have been demonstrated to modulate several fundamental physiological processes, including cell cycle progression, cell motility and migration, and cell differentiation. These processes play important roles in maintaining cardiovascular health. However, LIMK activity in healthy and pathological states of the cardiovascular system is poorly characterized. This review highlights the cellular and molecular mechanisms involved in LIMK activation and inactivation, examining its roles in the pathophysiology of vascular and cardiac diseases such as hypertension, aneurysm, atrial fibrillation, and valvular heart disease. It addresses the LIMKs' involvement in processes that support cardiovascular health, including vasculogenesis, angiogenesis, and endothelial mechanotransduction. The review also features how LIMK activity participates in endothelial cell, vascular smooth muscle cell, and cardiomyocyte physiology and its implications in pathological states. A few recent preclinical studies demonstrate the therapeutic potential of LIMK inhibition. We conclude by proposing that future research should focus on the potential clinical relevance of LIMK inhibitors as therapeutic agents to reduce the burden of cardiovascular disease and improve patient outcomes.

Background: Aedes (Stegomyia) albopictus (Skuse) is an invasive and widespread mosquito species that can transmit dengue, chikungunya, yellow fever, and Zika viruses. Its control heavily relies on the use of insecticides. However, the efficacy of the insecticide-based intervention is threatened by the increasing development of resistance to available insecticides. Understanding the current status and potential mechanisms of insecticide resistance is an important prerequisite for devising strategies to maintain the sustainability of vector control programs. In this study, we investigated the current status and probable candidate detoxification genes associated with insecticide resistance in the Asian tiger mosquito in Beijing, the capital city of China.

Methods: Bioassays were conducted on three field populations of Ae. albopictus collected from urban communities in Beijing by exposure to diagnostic doses of permethrin, deltamethrin, malathion, and propoxur. Differentially expressed genes (DEGs) associated with insecticide resistance were screened by transcriptomic analysis using Illumina RNA sequencing data (RNA-seq) from 12 independent RNA libraries constructed from female strains of the three field populations and one susceptible strain.

Results: The bioassay results indicated that all the three field populations were resistant to propoxur (carbamate), deltamethrin, and permethrin (pyrethroids), but susceptible to malathion (organophosphate). Eighteen (18) cytochrome P450s (P450s), five (5) glutathione S-transferases (GSTs), four (4) carboxy/cholinesterases (CCEs), eight (8) UDP-glycosyltransferases (UGTs), and three (3) ATP-binding cassette transporters (ABCs) were found to be significantly overexpressed in the three field populations relative to the susceptible strain via transcriptomic analysis.

Conclusion: This study demonstrates that the Ae. albopictus field populations in Beijing exhibit multiple phenotypic resistance to commonly used pyrethroids and carbamate. The identification of a number of DEGs associated with insecticide resistance indicates that the mechanisms underlying resistance in field populations are complicated, and detoxifying enzymes may play important roles. The multiple resistance status detected in the three field populations suggests that resistance management strategies such as insecticide rotation and non-chemical-based measures should be implemented in order to sustain effective control of the disease vector and vector-borne diseases.

Introduction: This study aimed to investigate whether individualizing autonomic recovery periods between resistance training (RT) sessions (IND) using heart rate variability (HRV), measured by the root mean square of successive R-R interval differences (RMSSD), would lead to greater and more consistent improvements in muscle strength, muscle mass, and functional performance in older women compared to a fixed recovery protocol (FIX).

Methods: Twenty-one older women (age 66.0 ± 5.0 years old) were randomized into two different protocols (IND: n = 11; FIX: n = 10) and completed 7 weeks of RT. Measurements of RMSSD were performed within a five-day period to establish baseline values. The RMSSD values determined whether participants were recovered from the previous session. The assessments included muscle cross-sectional area (CSA), one-repetition maximum (1RM), peak torque (PT), rate of force development (RFD), chair stand (CS), timed up and go (TUG), 6-minutes walking (6MW), and maximum gait speed (MGS).

Results: There were no significant (P > 0.05) group vs. time interactions. There were significant main effects of time (P < 0.05) for CSA, 1RM, PT, TUG, CS, 6MW, and MGS, while no significant changes were observed for RFD (P > 0.05).

Conclusion: IND does not seem to enhance responses in muscle mass, strength, and functional performance compared FIX in healthy older women.

Enhanced hepatic gluconeogenesis plays an important role in exercise glucose homeostasis when hepatic glycogen stores are depleted. Livers from trained animals demonstrate greater rates of gluconeogenesis in the presence of elevated substrate with and without hormonal stimulation. Training has been reported to have a particularly profound impact on norepinephrine-stimulated gluconeogenesis, but this was only demonstrated in the presence of other gluconeogenic hormones. Here we reexamine the impact of endurance training on norepinephrine-stimulated gluconeogenesis in the absence of any other hormones. Isolated hepatocytes from trained and untrained rats were incubated in 6 mM lactate with various concentrations of norepinephrine (0 nM-20 nM). Absent norepinephrine, gluconeogenic rates were significantly greater from trained hepatocytes compared to controls (97.2 ± 6.7 vs 57.6 ± 8.7 nmol/mg protein; p < 0.01). In the presence of NE (0.5-20 nM), gluconeogenesis from trained liver cells was significantly greater at all NE concentrations compared to controls. The NE-stimulated increase in gluconeogenesis above basal (0 nM NE) was also greater for trained vs control (36% vs 19%, respectively). Concomitant with the max NE-stimulated increase in gluconeogenesis, lactate uptake was significantly elevated for trained vs. control hepatocytes (307.22 ± 44.5 vs 124.5 ± 23.9 nmol/mg protein; p < 0.01), with lactate uptake quantitatively accounting for the entire increase in gluconeogenesis for trained hepatocytes. Endurance training was also observed to significantly elevate glucose production in presence of 0.6 mM palmitate, both in the absence and presence of NE. These findings confirm that hepatocytes from endurance-trained animals demonstrate enhanced rates of NE-stimulated gluconeogenesis, as well as palmitate-stimulated glucose production.