Impact of Non-Invasive Ventilation on Sympathetic Nerve Activity in Chronic Obstructive Pulmonary Disease.

PURPOSE: Chronic obstructive pulmonary disease (COPD) is associated with elevated sympathetic nerve activity, which is probably linked to an increased cardiovascular risk, and may contribute to muscle dysfunction by heightened muscle vasoconstrictor drive. We hypothesized that resistive unloading of respiratory muscles by intermittent non-invasive ventilation (NIV) reduces sympathetic tone at rest and during subsequent handgrip exercise in patients with COPD. METHODS: Muscle sympathetic nerve activity (MSNA) in the peroneal nerve, heart rate, blood pressure, CO2, and SpO2 were continuously recorded in 5 COPD patients with intermittent NIV and 11 control COPD patients without NIV. Static and dynamic handgrip exercises were performed before and after NIV. RESULTS: At baseline, heart rate-adjusted MSNA (bursts/100 heart beats) did not differ between groups. NIV did not significantly affect MSNA levels at rest. However, during handgrip exercises directly following NIV, MSNA was lower than before, which was significant for dynamic handgrip (67.00 ± 3.70 vs. 62.13 ± 4.50 bursts/100 heart beats; p = 0.035 in paired t test). In contrast, MSNA (non-significantly) increased in the control group during repeated dynamic or static handgrip. During dynamic handgrip, tCO2 was lower after NIV than before (change by -5.04 ± 0.68 mmHg vs. -0.53 ± 0.64 in the control group; p = 0.021), while systolic and diastolic blood pressure did not change significantly. CONCLUSIONS: NIV reduces sympathetic activation during subsequent dynamic handgrip exercise and thereby may elicit positive effects on the cardiovascular system as well as on muscle function in patients with COPD.

Sympathetic Activation is Associated with Exercise Limitation in COPD.

Exercise intolerance, skeletal muscle dysfunction, and reduced daily activity are central in COPD patients and closely related to quality of life and prognosis. Studies assessing muscle exercise have revealed an increase in sympathetic outflow as a link to muscle hypoperfusion and exercise limitation. Our primary hypothesis was that muscle sympathetic nerve activity (MSNA) correlates with exercise limitation in COPD. MSNA was evaluated at rest and during dynamic or static handgrip exercise. Additionally, we assessed heart rate, blood pressure, CO2 tension, oxygen saturation (SpO2), and breathing frequency. Ergospirometry was performed to evaluate exercise capacity. We assessed MSNA of 14 COPD patients and 8 controls. In patients, MSNA was negatively correlated with peak oxygen uptake (VO2% pred) (r = -0.597; p = 0.040). During dynamic or static handgrip exercise, patients exhibited a significant increase in MSNA, which was not observed in the control group. The increase in MSNA during dynamic handgrip was highly negatively correlated with peak exercise capacity in Watts (w) and peak oxygen uptake (VO2/kg) (r = -0.853; p = 0.002 and r = -0.881; p = 0.002, respectively). Our study reveals an association between increased MSNA and limited exercise capacity in patients with COPD. Furthermore, we found an increased sympathetic response to moderate physical exercise (handgrip), which may contribute to exercise intolerance in COPD.

Chemical Speciation and Quantitative Evaluation of Heavy Metal Pollution Hazards in Two Army Shooting Range Backstop Soils.

The chemical speciation and ecological risk assessment of heavy metals in two shooting range backstop soils in Korea were studied. Both soils were highly contaminated with Cd, Cu, Pb, and Sb. The chemical speciation of heavy metals reflected the present status of contamination, which could help in promoting management practices. We-rye soil had a higher proportion of exchangeable and carbonate bound metals and water-extractable Cd and Sb than the Cho-do soil. Bioavailable Pb represented 42 % of the total Pb content in both soils. A significant amount of Sb was found in the two most bioavailable fractions, amounting to ~32 % in the soil samples, in good agreement with the batch leaching test using water. Based on the values of ecological risk indices, both soils showed extremely high potential risk and may represent serious environmental problems.

Performance Analysis of Automatic Integrated Long-Range RFID and Webcam System.

In the academic environment, checking attendance can help lecturers better evaluate students' performance in university. Traditional attendance checking has some disadvantages, which are wasting time and effort. The automatic attendance monitoring system, on the other hand, not only can help us solve these drawbacks but also bring a high-accuracy result compared to manually checking. The method uses ultra-high-frequency (UHF) RFID technology with four circularly polarized antennas, combined with the high-definition camera system used for face recognition that allows the system to recognize students' faces. The system will check the attendance of students in offline classes through an RFID reader and camera which are set up in classrooms. In the case of online study in which students learn from home, the system can use students' cameras directly from their laptops and smartphones to recognize their faces and check attendance. The web-based information system has real-time updates with attendance monitoring that allows the lecturer to review or determine the student's attendance status. In the event of unexpected issues on the student side, the system enables lecturers to check attendance manually after receiving the student's request. Our system, furthermore, can automatically generate a weekly report about student's learning status in each class and provide the overall proportion of students' commitment to attending classes for the lecturer. This paper brings some initial simulations of the system to give a more detailed picture of how the new system works and interacts. Besides, this manuscript provides a detailed performance analysis about the system with RFID and camera, then has an evaluation based on class' learning outcome. The time, precision, and accuracy of our system are considered.

Heavy metal stabilization in contaminated soil by treatment with calcined cockle shell.

In several previous studies, the efficacy of various liming waste materials on the immobilization of heavy metals has been tested and it was found that soils contaminated with heavy metals can be stabilized using this technique. Since lime (CaO) has been identified as the main phase of calcined cockle shell (CCS), it was hypothesized that CCS could be used as a soil amendment to immobilize heavy metals in soil. However, to date, no studies have been conducted using CCS. In this study, the effectiveness of CCS powder on the immobilization of Cd, Pb, and Zn in mine tailing soil was evaluated. After 28 days of incubation, the treated soil samples were exposed to weathering (four cycles of freezing-thawing and four cycles of wetting-drying) for 8 days before being subjected to a leaching test. The results of this study revealed that the soil pH increased from 7.5 to 12.2 with the addition of 5% CCS. A similar soil pH was obtained when the soil was amended with 5% pure CaO. By leaching with 0.1 M HCl, extracted Cd, Pb, and Zn were reduced by up to 85, 85, and 91%, respectively. Therefore, CCS is suggested as a low-cost lime-based soil amendment for stabilizing heavy metals in abandoned mining sites.

Effects of varenicline on sympatho-vagal balance and cue reactivity during smoking withdrawal: a randomised placebo-controlled trial.

BACKGROUND: Varenicline is an effective smoking cessation medication. Some concern has been raised that its use may precipitate adverse cardiovascular events although no patho-physiological mechanism potentially underlying such an effect has been reported. The aim of this study was to test the hypothesis that varenicline impacts on sympatho-vagal balance during smoking withdrawal. METHODS: In this randomised, placebo-controlled trial, muscle sympathetic nerve activity (MSNA), baroreflex sensitivity (BRS), heart rate, and blood pressure were assessed in 17 smokers four weeks before a quit attempt (baseline) and again on the third day of that quit attempt (acute smoking withdrawal). RESULTS: Regarding the primary endpoint of our study, we did not find a significant effect of varenicline compared to placebo on changes in MSNA burst incidence between baseline and acute smoking withdrawal (-3.0 ± 3.3 vs.-3.9 ± 5.0 bursts/100 heart beats; p = 0.308). However, heart rate and systolic blood pressure significantly decreased in the placebo group only, while no significant changes in these parameters were observed in the varenicline group. Exposure to smoking cues during acute withdrawal lead to a significant increase of heart rate in the placebo group, while heart rate decreased in the varenicline group, and the difference in these changes was significant between groups (+2.7 ± 1.0 vs.-1.8 ± 0.5 1/min; p = 0.002). In all 17 participants combined, a significant increase in heart rate during smoking cue exposure was detected in subjects who relapsed in the course of six weeks after the quit date compared to those who stayed abstinent (+2.5 ± 1.2 vs.-1.1 ± 0.7; p = 0.018). Six-week abstinence rates were higher in the varenicline group compared to placebo (88 vs. 22 % p = 0.015). CONCLUSION: We did not find evidence of adverse effects of varenicline on sympatho-vagal balance. Varenicline probably blunts the heart rate response to smoking cues, which may be linked to improved cessation outcome.