Altered spontaneous brain activity during dobutamine challenge in healthy young adults: A resting-state functional magnetic resonance imaging study

IntroductionThere is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults.MethodsForty-eight right-handed healthy participants (43 males and 5 females, range: 22–34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods—regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)—were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart.ResultsResults showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF.DiscussionThese findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management

Determination of inner pressure for fluid inclusions by Raman spectroscopy and its application

Using a Diamond Anvil Cell combined with micro Raman spectroscopy, the quantitative relations among Raman shifts, pressure and temperature were obtained for the vibration of O–H in H2O–NaCl, C–O in CO32−, S–O in SO42− and C–H in n-heptane-cyclohexane. Based on the quantitative relationships obtained, it is possible to determine the inner pressure for single fluid inclusions and to further determine the isochore of the systems. It is not only helpful to obtain the forming temperatures and pressures of the enclosing minerals, but also to be able to provide information concerning the chemical compositions of the fluid inclusions

Pyrolysis characteristics of tobacco stem after different solvent leaching treatments

The considerable amounts of alkaloids in tobacco stem (TS) make it wasteful and environmentally detrimental to directly pyrolyze it. This paper reveals the effects of leaching treatments with different solvents (hydrochloric acid, water and ethyl alcohol) on the pyrolysis characteristics of TS using TG-FTIR and Py-GC-MS. Alkaloids mainly consisting of nicotine were almost completely removed by leaching treatments, leading to the reduction of the N content in treated samples and the reduction of N-containing compounds in the obtained tar by Py-GC-MS. Potassium and calcium, which are the two main cations in TS, were removed completely by acid leaching, whereas calcium is resistant to water and alcohol. The removal of inorganic species in leached samples reduced the stability of TS at low temperatures (< similar to 270 degrees C) but improved it at high temperatures (270-490 degrees C). In addition, more sugars, such as levoglucosan, and high-mass weight species were generated by pyrolysis of TS leached by several solvents, especially acid. Different from water and alcohol, hydrochloric acid strongly destroyed the matrix structure of TS and lowered its thermal stability. Because of the removal of acid-soluble lignin by hydrochloric acid, the generation of benzenes during pyrolysis were markedly inhibited

Dobutamine-induced alternations in cerebral blood flow of healthy adults: a 3D pseudocontinuous arterial spin labeling study

Abstract Background It is unclear whether dobutamine, commonly used clinically in echocardiography and short-term congestive heart failure treatment for promoting increased myocardial contractility, affects brain microcirculatory behavior. Cerebral microcirculation plays an important role in ensuring adequate oxygen transport. Therefore, we investigated the effects of dobutamine on cerebral hemodynamics. Methods Forty-eight healthy volunteers without cardiovascular or cerebrovascular disease underwent MRI to obtain cerebral blood flow (CBF) maps using 3D pseudocontinuous arterial spin labeling before and during the dobutamine stress test. Additionally, cerebrovascular morphology was obtained based on 3D-time-off-light (3D-TOF) magnetic resonance angiography (MRA). Electrocardiogram, heart rate (HR), respiration rate (RR), blood pressure, and blood oxygen were simultaneously recorded before and during dobutamine injection and during recovery (not during MRI). The anatomic features of the circle of Willis and the basilar artery (BA) diameter were assessed on MRA images by two radiologists with extensive neuroimaging experience. Binary logistic regression was used to test for the independent determinants of CBF changes. Results HR, RR, systolic (SBP), and diastolic blood pressure (DBP) significantly increased after dobutamine infusion. Blood oxygen levels remained similar. Compared to the CBF in the resting state, the CBF values exhibited significantly lower CBF levels in both grey matter and white matter. Furthermore, compared with the CBF in the resting state, that in the stress state was decreased in the anterior circulation, mainly in the frontal lobe (voxel level P < 0.001, pixel level P < 0.05). Logistic regression showed that body mass index (BMI; odds ratio [OR] 5.80, 95% confidence interval [CI] 1.60–21.01, P = 0.008], resting SBP (OR 0.64, 95% CI 0.45–0.92, P = 0.014), and BA diameter (OR 11.04, 95% CI 1.05–116.53, P = 0.046) were significantly associated with frontal lobe CBF changes. Conclusions Dobutamine-induced stress significantly decreased CBF in the frontal lobe anterior circulation. Individuals with a high BMI and low SBP during the dobutamine stress test are more likely to have a stress-induced CBF decrease. Thus, attention should be paid to blood pressure, BMI, and cerebrovascular morphology of patients undergoing dobutamine stress echocardiography or those receiving intensive care or anesthesia

Formation of styrene monomer, dimer and trimer in the primary volatiles produced from polystyrene pyrolysis in a wire-mesh reactor

© 2016 Elsevier Ltd.This paper reports the formation of styrene monomer, dimer and trimer in the primary volatiles during fast pyrolysis of polystyrene in a wire-mesh reactor where secondary reactions of primary pyrolysis volatiles are minimized. Styrene monomer is the most abundant product in the primary volatiles from polystyrene pyrolysis, with a selectivity of 48-69 wt% depending on pyrolysis temperature, while dimer and trimer only have selectivities of 8-10 and 9-30 wt%, respectively. High temperature promotes the formation of styrene monomer and suppresses the formation of styrene trimer, but with little effect on the formation of styrene dimer. It is also found that the selectivities of styrene monomer, dimer and trimer show negligible changes with increasing the conversion level at the same pyrolysis temperature. The results suggest neither 1,3-hydrogen transfer nor intermolecular benzyl radical addition is the dominant formation mechanism for styrene dimer. The styrene dimer is more likely produced via the 1,7- and 7,3-hydrogen transfer mechanism