Electrical impedance tomography as a bedside assessment tool for COPD treatment during hospitalization.

For patients with chronic obstructive pulmonary disease (COPD), the assessment of the treatment efficacy during hospitalization is of importance to the optimization of clinical treatments. Conventional spirometry might not be sensitive enough to capture the regional lung function development. The study aimed to evaluate the feasibility of using electrical impedance tomography (EIT) as an objective bedside evaluation tool for the treatment of acute exacerbation of COPD (AECOPD). Consecutive patients who required hospitalization due to AECOPD were included prospectively. EIT measurements were conducted at the time of admission and before the discharge simultaneously when a forced vital capacity maneuver was conducted. EIT-based heterogeneity measures of regional lung function were calculated based on the impedance changes over time. Surveys for attending doctors and patients were designed to evaluate the ease of use, feasibility, and overall satisfaction level to understand the acceptability of EIT measurements. Patient-reported outcome assessments were conducted. User's acceptance of EIT technology was investigated with a five-dimension survey. A total of 32 patients were included, and 8 patients were excluded due to the FVC maneuver not meeting the ATS criteria. Spirometry-based lung function was improved during hospitalization but not significantly different (FEV1 %pred.: 35.8% ± 6.7% vs. 45.3% ± 8.8% at admission vs. discharge; p = 0.11. FVC %pred.: 67.8% ± 0.4% vs. 82.6% ± 5.0%; p = 0.15. FEV1/FVC: 0.41 ± 0.09 vs. 0.42 ± 0.07, p = 0.71). The symptoms of COPD were significantly improved, but the correlations between the improvement of symptoms and spirometry FEV1 and FEV1/FVC were low (R = 0.1 and -0.01, respectively). The differences in blood gasses and blood tests were insignificant. All but one EIT-based regional lung function parameter were significantly improved after hospitalization. The results highly correlated with the patient-reported outcome assessment (R > 0.6, p < 0.001). The overall acceptability score of EIT measurement for both attending physicians and patients was high (4.1 ± 0.8 for physicians, 4.5 ± 0.5 for patients out of 5). These results demonstrated that it was feasible and acceptable to use EIT as an objective bedside evaluation tool for COPD treatment efficacy.

Visualizing pursed lips breathing of patients with chronic obstructive pulmonary disease through evaluation of global and regional ventilation using electrical impedance tomography.

Objective. This study aims to explore the possibility of using electrical impedance tomography (EIT) to assess pursed lips breathing (PLB) performance of patients with chronic obstructive pulmonary disease (COPD).Methods. 32 patients with COPD were assigned equally to either the conventional group or the EIT guided group. All patients were taught to perform PLB by a physiotherapist without EIT in the conventional group or with EIT in the EIT guided group for 10 min. The ventilation of all patients in the final test were continuously monitored using EIT and the PLB performances were rated by another physiotherapist before and after reviewing EIT. The global and regional ventilation between two groups as well as between quite breathing (QB) and PLB were compared and rating scores with and without EIT were also compared.Results.For global ventilation, the inspiratory depth and the ratio of expiratory-to-inspiratory time during PLB was significantly larger than those during QB for both group (P< 0.001). The inspiratory depth and the ratio of expiratory-to-inspiratory time during PLB in the EIT guided group were higher compared to those in the conventional group (P< 0.001), as well as expiratory flow expiratory uniformity and respiratory stability were better (P< 0.001). For regional ventilation, center of ventilation significantly decreased during PLB (P< 0.05). The expiratory time constant during PLB in the EIT guided group was greater than that in the conventional group (P< 0.001). Additionally, Bland-Altman plots analysis suggested a high concordance between subjective rating and rating with the help of EIT, but the score rated after EIT observation significantly lower than that rated subjectively in both groups (score drop of -2.68 ± 1.1 in the conventional group and -1.19 ± 0.72 in the EIT guided group,P< 0.01).Conclusion.EIT could capture the details of PLB maneuver, which might be a potential tool to quantitatively evaluate PLB performance and thus assist physiotherapists to teach PLB maneuver to patients.

Monitoring of spontaneous pneumothorax using electrical impedance tomography: A case report.

Pneumothorax is an emergency in thoracic surgeries and respiratory medicine. A technique is warranted for real-time monitoring of pneumothorax at the bedside so that rapid diagnosis and timely intervention can be achieved. We report herein a case in which electrical impedance tomography (EIT) was employed at the bedside to monitor lung ventilation of a patient with spontaneous pneumothorax during treatment. It was found that the affected side/healthy side ventilation ratio and global inhomogeneity were strongly correlated with the severity of pneumothorax. The use of EIT allowed intuitive observation of the effect of pneumothorax on ventilation, which helped the doctors make immediate diagnosis and intervention. After timely and successful treatment, the patient was discharged. This is the first case reporting a complete therapeutic course of spontaneous pneumothorax assessed with EIT. Our case demonstrated that EIT could monitor regional ventilation loss of the affected side of pneumothorax patients at the bedside, and dynamically assess the treatment effect of pneumothorax, which provides an important imaging basis for clinical pneumothorax treatment.

Evaluation of adjacent and opposite current injection patterns for a wearable chest electrical impedance tomography system.

Objective.Wearable electrical impedance tomography (EIT) can be used to monitor regional lung ventilation and perfusion at the bedside. Due to its special system architecture, the amplitude of the injected current is usually limited compared to stationary EIT system. This study aims to evaluate the performance of current injection patterns with various low-amplitude currents in healthy volunteers.Approach.A total of 96 test sets of EIT measurement was recorded in 12 healthy subjects by employing adjacent and opposite current injection patterns with four amplitudes of small current (i.e. 1 mA, 500 uA, 250 uA and 125 uA). The performance of the two injection patterns with various currents was evaluated in terms of signal-to-noise ratio (SNR) of thorax impedance, EIT image metrics and EIT-based clinical parameters.Main results.Compared with adjacent injection, opposite injection had higher SNR (p< 0.01), less inverse artifacts (p< 0.01), and less boundary artifacts (p< 0.01) with the same current amplitude. In addition, opposite injection exhibited more stable EIT-based clinical parameters (p< 0.01) across the current range. For adjacent injection, significant differences were found for three EIT image metrics (p< 0.05) and four EIT-based clinical parameters (p< 0.01) between the group of 125 uA and the other groups.Significance.For better performance of wearable pulmonary EIT, currents greater than 250 uA should be used in opposite injection, 500 uA in adjacent one, to ensure a high level of SNR, a high quality of reconstructed image as well as a high reliability of clinical parameters.

The Influence of Breathing Exercises on Regional Ventilation in Healthy and Patients with Chronic Obstructive Pulmonary Disease.

We hypothesized that the respiratory exercises have uniform effects on ventilation in healthy subjects but the effects varied in patients with chronic obstructive pulmonary disease (COPD). In this study, a total of 30 healthy volunteers and 9 patients with COPD were included. Data were recorded continuously during (1) diaphragmatic breathing; (2) pursed lip breathing with full inhalation; (3) pursed lip combining diaphragmatic breathing. The sequence of the three breathing exercises was randomized using machine generated random permutation. Spatial and temporal ventilation distributions were evaluated with electrical impedance tomography. Results showed that, tidal volume was significantly larger during various breathing exercises compared to quiet tidal breathing, in both healthy and COPD (p < 0.01). However, for other EIT-based parameters, statistical significances were only observed in healthy volunteers, not in patients. Diaphragmatic breathing alone might not be able to decrease functional residual capacity in COPD and the effect varied largely from patient to patient (6:3, decrease vs. increase). Ventilation distribution moved toward ventral regions in healthy during breathing exercises (p < 0.0001). Although this trend was observed in the COPD, the differences were not significant. Ventilation became more homogeneous when diaphragmatic breathing technique was implemented (p < 0.0001). Again, the improvements were not significant in COPD. Regional ventilation delay was relatively high in COPD and comparable in various breathing periods. In conclusions, the impact of pursed lip and diaphragmatic breathing varied in different patients with COPD. Breathing exercise may need to be individualized to maximize the training efficacy with help of EIT.

The influence of gravity on electrical impedance tomography measurements during upper body position change.

Objective: The aim of the study was to examine the influence of gravity on regional ventilation measured by electrical impedance tomography (EIT) with the standard electrode belt position at the 5th intercostal space during tilting from supine to sitting positions. Methods: A total of 30 healthy volunteers were examined prospectively in supine position during quiet tidal breathing. Subsequently, the bed was tilted so that the upper body of the subjects achieved 30, 60 and 90° every 3 min. Regional ventilation distribution and end-expiratory lung impedance (EELI) were monitored with EIT throughout the whole experiment. Absolute tidal volumes were measured with spirometry and the volume-impedance ratio was calculated for each position. Results: The volume-impedance ratio did not differ statistically between the studied body positions but 11 subjects exhibited a large change in ratio at one of the positions (outside 99.3% coverage). In general, ventilation distribution became more heterogeneous and moved towards dorsal regions as the upper body was tilted to 90-degree position. EELI increased and tidal volume decreased. The lung regions identified at various positions differed significantly. Conclusion: Gravity has non-negligible influence on EIT data, as the upper body tilted from supine to sitting positions. The standard electrode belt position might be reconsidered if ventilation distribution is to be compared between supine and sitting positions.

Discrimination between human normal renal tissue and renal cell carcinoma by dielectric properties using in-vitro BIA.

Renal cell carcinoma (RCC) poses a serious threat to human health, which urgently requires a method that can quickly distinguish between human normal renal tissue (NRT) and RCC for the purpose of accurate detection in clinical practice. The significant difference in cell morphology between NRT and RCC tissue underlies the great potential of the bioelectrical impedance analysis (BIA) to distinguish two types of human tissues. The study aims to achieve such discrimination through comparison of their dielectric properties within the frequency range from 10 Hz to 100 MHz. The dielectric properties of 69 cases of human normal and cancer renal tissue were measured 15 min after tissue isolation in a strictly controlled environment (37°C, 90% humidity). In addition to the impedance parameters (resistivity, conductivity and relative permittivity), the characteristic parameters extracted from the Cole curve were also compared between NRT and RCC. Furthermore, a novel index, distinguishing coefficient (DC), was used to obtain the optimal frequency for discrimination between NRT and RCC. In terms of impedance parameters, the RCC conductivity at low frequencies (<1 kHz) was about 1.4 times as large as that of NRT, and its relative permittivity was also significantly higher (p < 0.05). In terms of characteristic parameters, two characteristic frequencies (14.1 ± 1.1 kHz and 1.16 ± 0.13 MHz) were found for NRT while only one for RCC (0.60 ± 0.05 MHz). A significant difference of low-frequency resistance (R0) between RCC and NRT was also observed (p < 0.05). As for the new index DC, relative permittivity DCs below 100 Hz and at around 14 kHz were both greater than 1. These findings further confirm the feasibility of discrimination between RCC and NRT and also provide data in favor of further clinical study of BIA to detect the surgical margins.

Synergistic effects of transcutaneous vagus nerve stimulation and inhibitory control training on electrophysiological performance in healthy adults.

Transcutaneous vagal nerve stimulation (tVNS) is a non-invasive nerve stimulation technique that exerts a positive "exogenous" online neuromodulatory effect on inhibitory control (IC). Additionally, IC training (ICT) is an effective approach for enhancing IC via the "endogenous" activation of brain regions implicated in this process. The aim of the present study was to examine the synergistic effects of tVNS and ICT on IC enhancement. For this, we measured the changes in neural activity in frontal, fronto-central, and central regions in the time domain of the N2 component and the frequency domain of alpha power during the stop signal task. A total of 58 participants were randomly divided into four groups that received five sessions of either ICT or sham ICT with either online tVNS or sham tVNS. No differences in N2 amplitude were detected after any of the interventions. However, N2 latency shortened after tVNS + ICT in frontal, fronto-central, and central regions. N2 latency shortened after the intervention of sham tVNS + ICT in frontal region. Moreover, alpha power after tVNS + ICT intervention was larger than those of the other interventions in frontal, fronto-central, and central regions. The obtained electrophysiological data suggested that combining tVNS with ICT has synergistic ameliorative effects on IC, and provide evidence supporting the IC-enhancing potential of tVNS combined with ICT.

Histone methyltransferase Setdb1 mediates osteogenic differentiation by suppressing the expression of miR-212-3p under mechanical unloading.

Emerging evidence indicates that multiple mechanisms are involved in bone loss induced by mechanical unloading. Thus far, few study has established the pathophysiological role of histone modification for osteogenic differentiation under mechanical unloading. Here we demonstrated that the histone H3 lysine 9 (H3K9) methyltransferase Setdb1, which was sensitive to mechanical unloading, was increased during osteogenic differentiation of MC3T3-E1 cells for the first time. Knockdown of Setdb1 significantly blocked osteoblast function in vivo and in vitro. Through bioinformatics analysis of candidate miRNAs regulated by H3K9me3, we further identified that Setdb1 inhibited the expression of miR-212-3p by regulating the formation of H3K9me3 in the promoter region. Mechanically, we revealed that miR-212-3p was upregulated under mechanical unloading and suppressed osteogenic differentiation by directly downregulating High mobility group box 1 protein (Hmgb1) expression. Furthermore, we verified the molecular mechanism of the SETDB1/miR-212-3p/HMGB1 pathway in hFOB cells under mechanical unloading. In summary, these data demonstrate the essential function of the Setdb1/miR-212-3p/Hmgb1 pathway in osteogenic differentiation under mechanical unloading, and present a potential protective strategies against bone loss induced by mechanical unloading.

Exosomes from Microvascular Endothelial Cells under Mechanical Unloading Inhibit Osteogenic Differentiation via miR-92b-3p/ELK4 Axis.

Mechanical unloading-related bone loss adversely harms astronauts' health. Nevertheless, the specific molecular basis underlying the phenomenon has not been completely elucidated. Although the bone microvasculature contributes significantly to bone homeostasis, the pathophysiological role of microvascular endothelial cells (MVECs) in bone loss induced by mechanical unloading is not apparent. Here, we discovered that MC3T3-E1 cells could take up exosomes produced by MVECs under clinorotation-unloading conditions (Clino Exos), which then prevented MC3T3-E1 cells from differentiating into mature osteoblasts. Moreover, miR-92b-3p was found to be highly expressed in both unloaded MVECs and derived exosomes. Further experiments demonstrated that miR-92b-3p was transferred into MC3T3-E1 cells by exosomes, resulting in the suppression of osteogenic differentiation, and that encapsulating miR-92b-3p inhibitor into the Clino Exos blocked their inhibitory effects. Furthermore, miR-92b-3p targeted ELK4 and the expression of ELK4 was lessened when cocultured with Clino Exos. The inhibitor-92b-3p-promoted osteoblast differentiation was partially reduced by siRNA-ELK4. Exosomal miR-92b-3p secreted from MVECs under mechanical unloading has been shown for the first time to partially attenuate the function of osteoblasts through downregulation of ELK4, suggesting a potential strategy to protect against the mechanical unloading-induced bone loss and disuse osteoporosis.

Bioinformatic analysis of the RNA expression patterns in microgravity-induced bone loss.

Researchers have linked microgravity in space to the significant imbalance between bone formation and bone resorption that induces persistent bone loss in load-bearing bones. However, the underlying molecular mechanisms are still unclear, which hinders the development of therapeutic measures. The aim of this study was to identify hub genes and explore novel molecular mechanisms underlying microgravity-induced bone loss using transcriptome datasets obtained from the GEO and SRA databases. In summary, comparative RNA expression pattern studies that differ in species (Homo or Mus), models (in vitro or in vivo), microgravity conditions (real microgravity or ground-based simulators) and microgravity duration showed that it is difficult to reach a consistent conclusion about the pathogenesis of microgravity-induced bone loss across these studies. Even so, we identified 11 hub genes and some miRNA-mRNA interactions mainly based on the GSE100930 dataset. Also, the expression of CCL2, ICAM1, IGF1, miR-101-3p and miR-451a markedly changed under clinorotation-microgravity condition. Remarkedly, ICAM1 and miR-451a were key mediators of the osteogenesis of hMSCs under clinorotation-microgravity condition. These findings provide novel insights into the molecular mechanisms of bone loss during microgravity and could indicate potential targets for further countermeasures against this condition.

The neuroelectrophysiological and behavioral effects of transcranial direct current stimulation on executive vigilance under a continuous monotonous condition.

A prolonged period of vigilance task will lead to vigilance decrement and a drop in cognitive efficiency. Although transcranial direct current stimulation (tDCS) can be used to improve cognitive performance following vigilance decrement, the findings in this area of study are inconsistent. This study aims to identify the neuroelectrophysiological and behavioral effects of tDCS over the left dorsolateral prefrontal cortex (DLPFC) on executive vigilance under a continuous monotonous condition. We recruited 29 participants who randomly received 30 min active or sham tDCS before the vigilance task (anode electrode at the left DLPFC, cathode electrode at the right supraorbital area). Participants completed four sessions of vigilance task and five sessions of self-report sleepiness, Oddball task, and Go/Nogo task, for a total of about 5 h. EEG was acquired in real-time throughout the experiment. Repeated measures of ANOVA were utilized to analyze the evolution of each metric with task-on-time. The results demonstrated that subjective arousal state, vigilance performance, event-related potentials (ERPs), and EEG power were significantly affected by time on task. Brain stimulation did not significantly affect the evolution of subjective and objective executive vigilance performance, but significantly modulated spontaneous activity in the alpha and beta bands across the entire brain. The continuous enhancement of the prefrontal cortex increased P2 amplitude for the Oddball task, which was associated with the enhancement of the early stage of information processing. P3 amplitude had a temporary enhancement effect, which significantly decreased following a cognitive fatigue. tDCS had a continuous enhancement effect on N2 amplitude for the Go/Nogo task, which was associated with the enhanced inhibition of distracting stimuli. Together, the current data suggest that anodal tDCS over left DLPFC possibly enhances the early stage of relevant information processing and the inhibitory control of distracting stimuli during a continuous and monotonous vigilance task.

Methyltransferase Setdb1 Promotes Osteoblast Proliferation by Epigenetically Silencing Macrod2 with the Assistance of Atf7ip.

Bone loss caused by mechanical unloading is a threat to prolonged space flight and human health. Epigenetic modifications play a crucial role in varied biological processes, but the mechanism of histone modification on unloading-induced bone loss has rarely been studied. Here, we discovered for the first time that the methyltransferase Setdb1 was downregulated under the mechanical unloading both in vitro and in vivo so as to attenuate osteoblast proliferation. Furthermore, we found these interesting processes depended on the repression of Macrod2 expression triggered by Setdb1 catalyzing the formation of H3K9me3 in the promoter region. Mechanically, we revealed that Macrod2 was upregulated under mechanical unloading and suppressed osteoblast proliferation through the GSK-3ß/ß-catenin signaling pathway. Moreover, Atf7ip cooperatively contributed to osteoblast proliferation by changing the localization of Setdb1 under mechanical loading. In summary, this research elucidated the role of the Atf7ip/Setdb1/Macrod2 axis in osteoblast proliferation under mechanical unloading for the first time, which can be a potential protective strategy against unloading-induced bone loss.

Training and Transfer Effects of Combining Inhibitory Control Training With Transcutaneous Vagus Nerve Stimulation in Healthy Adults.

Inhibitory control training (ICT) is a promising method to improve individual performance of inhibitory control (IC). Recent studies have suggested transcutaneous vagus nerve stimulation (tVNS) as a novel approach to affect cognitive function owing to its ability to modulate the locus coeruleus-noradrenaline system. To examine the synergistic effects of combining ICT with tVNS, 58 young males in college were randomly assigned to four groups: ICT + tVNS, ICT + sham tVNS, sham ICT + tVNS, and sham ICT + sham tVNS. Participants were instructed to complete three sessions that comprised pre-training tests, a training session, and post-training tests sequentially. Results showed that the ICT + tVNS group significantly improved training and near-transfer effects on the stop-signal and Go/No-go tasks, and these effects were larger than those of the other groups. However, none of the groups exhibited the far-transfer effect on the color-word Stroop task. These results suggest that tVNS augments the intervention effects of training and similar inhibition tasks to achieve the synergistic effect; however, it does not modulate the effects of non-training tasks and obtain the far-transfer effect. ICT combined with tVNS may be a valuable intervention for improving IC in healthy individuals in certain industries and offers novel research ideas for using tVNS for cognitive improvement.

Circulating Exosomes from Mice with LPS-Induced Bone Loss Inhibit Osteoblast Differentiation.

Osteoimmunology focuses on the intermodulation between bone and the immune system. Lipopolysaccharide (LPS)-induced bone loss models are commonly used to investigate the interface between inflammation and osteoporosis. Circulating exosomes can regulate physiological and pathological processes through exosomal microRNAs and proteins. In this study, we observed reduced osteoblast number and bone formation in LPS-induced bone loss mice (LPS mice). Levels of circulating exosomes were increased by ~ twofold in LPS mice, and the expression of exosomal miRNAs was significantly changed. miRNAs (miRNA-125b-5p, miRNA-132-3p, and miRNA-214-3p) that were reported to inhibit osteoblast activity were significantly increased in the serum exosomes and bone tissues of LPS mice. Additionally, LPS-induced increases in exosomes significantly inhibited the osteogenic differentiation of MC3T3-E1 cells.

Removing Clinical Motion Artifacts During Ventilation Monitoring With Electrical Impedance Tomography: Introduction of Methodology and Validation With Simulation and Patient Data.

OBJECTIVE: Electrical impedance tomography (EIT) is a bedside tool for lung ventilation and perfusion assessment. However, the ability for long-term monitoring diminished due to interferences from clinical interventions and motion artifacts. The purpose of this study is to investigate the feasibility of the discrete wavelet transform (DWT) to detect and remove the common types of motion artifacts in thoracic EIT. METHODS: Baseline drifting, step-like and spike-like interferences were simulated to mimic three common types of motion artifacts. The discrete wavelet decomposition was employed to characterize those motion artifacts in different frequency levels with different wavelet coefficients, and those motion artifacts were then attenuated by suppressing the relevant wavelet coefficients. Further validation was conducted in two patients when motion artifacts were introduced through pulsating mattress and deliberate body movements. The db8 wavelet was used to decompose the contaminated signals into several sublevels. RESULTS: In the simulation study, it was shown that, after being processed by DWT, the signal consistency improved by 92.98% for baseline drifting, 97.83% for the step-like artifact, and 62.83% for the spike-like artifact; the signal similarity improved by 77.49% for baseline drifting, 73.47% for the step-like artifact, and 2.35% for the spike-like artifact. Results from patient data demonstrated the EIT image errors decreased by 89.24% (baseline drifting), 88.45% (step-like artifact), and 97.80% (spike-like artifact), respectively; the data correlations between EIT images without artifacts and the processed were all > 0.95. CONCLUSION: This study found that DWT is a universal and effective tool to detect and remove these motion artifacts.

The effects of emotional trait factors on simulated flight performance under an acute psychological stress situation.

Objective. Pilots are commonly exposed to some sources of emotional and cognitive stressors, especially for flight cadets, which have an important influence on flight safety. The present study aimed to study the relationship between emotional trait factors, emotional state, mental workload and simulated flight performance (SFP) under an acute psychological stress situation. Methods. Fifty-five undergraduates were included in the study. The Wong and Law emotional intelligence scale (WLEIS), state-trait anxiety inventory (STAI), stress rating questionnaire (SRQ) and National Aeronautics and Space Administration task load index (NASA-TLX) were used as data collection tools. Nine hours of simulated flight training were conducted in a simulator of the Type-6 Primary Trainer (Aviation University Air Force, China). The simulated flight assessment was taken as the acute psychological stressor. Results. SFP was negatively correlated with tensity and state anxiety. Emotional intelligence (EI) indirectly affected the SFP mediated by emotional state and workload, and emotional state had a mediating effect on the relationship between trait anxiety and SFP. Conclusions. The findings indicated that emotional trait factors (EI and trait anxiety) may indirectly affect SFP under an acute psychological stress situation, and emotional state (tensity and state anxiety) and mental workload played an important mediating role.

HDAC6 Negatively Regulates miR-155-5p Expression to Elicit Proliferation by Targeting RHEB in Microvascular Endothelial Cells under Mechanical Unloading.

Mechanical unloading contributes to significant cardiovascular deconditioning. Endothelial dysfunction in the sites of microcirculation may be one of the causes of the cardiovascular degeneration induced by unloading, but the detailed mechanism is still unclear. Here, we first demonstrated that mechanical unloading inhibited brain microvascular endothelial cell proliferation and downregulated histone deacetylase 6 (HDAC6) expression. Furthermore, HDAC6 promoted microvascular endothelial cell proliferation and attenuated the inhibition of proliferation caused by clinorotation unloading. To comprehensively identify microRNAs (miRNAs) that are regulated by HDAC6, we analyzed differential miRNA expression in microvascular endothelial cells after transfection with HDAC6 siRNA and selected miR-155-5p, which was the miRNA with the most significantly increased expression. The ectopic expression of miR-155-5p inhibited microvascular endothelial cell proliferation and directly downregulated Ras homolog enriched in brain (RHEB) expression. Moreover, RHEB expression was downregulated under mechanical unloading and was essential for the miR-155-5p-mediated promotion of microvascular endothelial cell proliferation. Taken together, these results are the first to elucidate the role of HDAC6 in unloading-induced cell growth inhibition through the miR-155-5p/RHEB axis, suggesting that the HDAC6/miR-155-5p/RHEB pathway is a specific target for the preventative treatment of cardiovascular deconditioning.

Real-time assessment of global and regional lung ventilation in the anti-gravity straining maneuver using electrical impedance tomography.

OBJECTIVE: Anti-gravity straining maneuver (AGSM) helps to reduce the occurrence of gravity-induced visual disturbances and loss of consciousness. An objective assessment of the AGSM is still missing during ground training. This study evaluated the feasibility of using electrical impedance tomography (EIT) to assess the performance of AGSM. METHODS: Eight undergraduates and eight teachers majoring in aerospace medicine were included in the study. An experienced professor from the department of aerospace medicine reviewed the key points of AGSM with each subject. EIT measurement was performed during AGSM. The global and regional ventilation were used to investigate the characteristics of AGSM. The professor and the subjects rated the performance of AGSM according to the maneuver requirements of AGSM (maximum 16 points) before and after reviewing the ventilations from EIT. RESULTS: For global ventilation, the relative depth of gas exchange and duration of exhalation of the teachers were larger than those of the students (p < 0.01), and stability of the teachers was better as well (p < 0.001). No difference in the duration of gas exchange and leakage during exhalation between the teachers and the students was found. For regional ventilation, the teachers had significantly increased ventral ventilation during AGSM implementation (p < 0.001) whereas students did otherwise. Additionally, the differences of rating scores with and without EIT were also significant. Significant reductions were found in rating scores with EIT assessed by the professor (4.5 ± 2.0, p < 0.001) and by the students themselves (3.9 ± 2.2, p < 0.001). The scores were systematically higher when the students rated themselves compared with the professor's rating (p < 0.001 for both with and without EIT). CONCLUSION: These findings demonstrated that EIT could objectively characterize the maneuver details of AGSM, which might provide a potential tool for real-time assessment of AGSM quality in an objective manner.

Regional ventilation distribution in healthy lungs: can reference values be established for electrical impedance tomography parameters?

BACKGROUND: Although electrical impedance tomography (EIT) is widely used for monitoring regional ventilation distribution, reference values have yet to be established for clinical use. The present study aimed to evaluate the feasibility of creating reference values for standard EIT parameters for potential clinical application. METHODS: A total of 75 participants with healthy lungs were included in this prospective study (male:female, 48:27; age, 34±14 years; height, 172±7 cm; weight, 73±12 kg). The subjects were examined during spontaneous breathing in the supine position. EIT measurements were performed at the level of the 4th intercostal space. Commonly used EIT-based parameters, including the center of ventilation (CoV), dorsal and most dorsal fractions of ventilation distribution (TVD and TVROI4 respectively), global inhomogeneity (GI) index, and standard deviation of regional ventilation delay index (RVDSD) were calculated. RESULTS: Following outlier detection, EIT data from 71 subjects were finally evaluated. The values of the evaluated parameters were: CoV, 48.7%±1.7%; TVD, 48.1%±5.4%; TVROI4, 7.1%±1.8%; GI, 0.49±0.04; and RVDSD, 7.0±2.0. The coefficients of variation for CoV and GI were low (0.03 and 0.07, respectively), but those for TVROI4 and RVDSD were comparatively high (0.26 and 0.28, respectively). None of the evaluated parameters showed a significant correlation with age. The GI index showed a weak but significant correlation with body mass index (R=0.29, P=0.01). The RVDSD was slightly higher in males than in females. CONCLUSIONS: Our study indicated that CoV and GI were stable parameters with small coefficients of variation in participants with healthy lungs. The creation of EIT parameter reference values for setting treatment targets may be feasible.