Multislice CT virtual endoscopy in pre-aortic stent grafting: optimization of scanning protocals

The purpose of this study was to investigate the optimal scanning protocols of multislice CT (MSCT) angiography in pre-aortic stent grafting, visualized on virtual endoscopy (VE). A series of scans were performed on a human aorta phantom with a 16-slice multislice CT scanner with the scanning protocols as follows: section thickness of 1.0/1.5/2.0/3.0 mm, pitch value of 1.0/1.25/1.5, and reconstruction interval of 50% overlap. Signal to noise ratio and standard deviation (SD) of the signal intensity on VE images were measured to determine the image quality in relation to MSCT scanning protocols. Subjective assessment was performed by two observers evaluating the degree of artefacts and the configuration of the renal ostium visualized on VE images. Our results showed that the scanning protocol with a section thickness of 2.0 mm resulted in the highest SNR and lowest SD compared to other protocols (p<0.05). Subjective assessment demonstrated that VE image quality was determined by section thickness, but independent of pitch values. We recommended the scanning protocol of section thickness 2.0 mm, pitch 1.5 with a reconstruction interval of 1.0 mm as the optimal one since it allows optimal visualization of VE images of aortic ostia, fewer artefacts and less radiation dose

Cellular cholesterol delivery, intracellular processing and utilization for biosynthesis of steroid hormones

Steroid hormones regulate diverse physiological functions such as reproduction, blood salt balance, maintenance of secondary sexual characteristics, response to stress, neuronal function and various metabolic processes. They are synthesized from cholesterol mainly in the adrenal gland and gonads in response to tissue-specific tropic hormones. These steroidogenic tissues are unique in that they require cholesterol not only for membrane biogenesis, maintenance of membrane fluidity and cell signaling, but also as the starting material for the biosynthesis of steroid hormones. It is not surprising, then, that cells of steroidogenic tissues have evolved with multiple pathways to assure the constant supply of cholesterol needed to maintain optimum steroid synthesis. The cholesterol utilized for steroidogenesis is derived from a combination of sources: 1) de novo synthesis in the endoplasmic reticulum (ER); 2) the mobilization of cholesteryl esters (CEs) stored in lipid droplets through cholesteryl ester hydrolase; 3) plasma lipoprotein-derived CEs obtained by either LDL receptor-mediated endocytic and/or SR-BI-mediated selective uptake; and 4) in some cultured cell systems from plasma membrane-associated free cholesterol. Here, we focus on recent insights into the molecules and cellular processes that mediate the uptake of plasma lipoprotein-derived cholesterol, events connected with the intracellular cholesterol processing and the role of crucial proteins that mediate cholesterol transport to mitochondria for its utilization for steroid hormone production. In particular, we discuss the structure and function of SR-BI, the importance of the selective cholesterol transport pathway in providing cholesterol substrate for steroid biosynthesis and the role of two key proteins, StAR and PBR/TSO in facilitating cholesterol delivery to inner mitochondrial membrane sites, where P450scc (CYP11A) is localized and where the conversion of cholesterol to pregnenolone (the common steroid precursor) takes place

Carbon dots for specific “off-on” sensing of Co\u3csup\u3e2+\u3c/sup\u3e and EDTA for in vivo bioimaging

Fluorescent carbon dots (CDs) were hydrothermally synthesized from a mixture of frozen tofu, ethylenediamine and phosphoric acid in an efficient 64% yield. The resulting CDs exhibit good water solubility, low cytotoxicity, high stability, and excellent biocompatibility. The CDs selectively and sensitively detect Co2+ through fluorescent quenching with a detection limit of 58 nM. Fluorescence can be restored through the introduction of EDTA, and this phenomenon can be used to quantify EDTA in solution with a detection limit of 98 nM. As both analytes are detected by the same CD platform, this is an “off-on” fluorescence sensor for Co2+ and EDTA. The technique\u27s robustness for real-world samples was illustrated by quantifying cobalt in tap water and EDTA in contact lens solution. The CDs were also evaluated for in vivo imaging as they show low cytotoxicity and excellent cellular uptake. In a zebrafish model, the CDs are rapidly adsorbed from the intestine into the liver, and are essentially cleared from the body in 24 h with no appreciable bioaccumulation. Their simple and efficient synthesis, combined with excellent physical and chemical performance, renders these CDs attractive candidates for theranostic applications in targeted “smart” drug delivery and bioimaging

320-row CT renal perfusion imaging in patients with aortic dissection: A preliminary study

Objective: To investigate the clinical value of renal perfusion imaging in patients with aortic dissection (AD) using 320-row computed tomography (CT), and to determine the relationship between renal CT perfusion imaging and various factors of aortic dissection. Methods: Forty-three patients with AD who underwent 320-row CT renal perfusion before operation were prospectively enrolled in this study. Diagnosis of AD was confirmed by transthoracic echocardiography. Blood flow (BF) of bilateral renal perfusion was measured and analyzed. CT perfusion imaging signs of AD in relation to the type of AD, number of entry tears and the false lumen thrombus were observed and compared. Results: The BF values of patients with type A AD were significantly lower than those of patients with type B AD (P = 0.004). No significant difference was found in the BF between different numbers of intimal tears (P = 0.288), but BF values were significantly higher in cases with a false lumen without thrombus and renal arteries arising from the true lumen than in those with thrombus (P = 0.036). The BF values measured between the true lumen, false lumen and overriding groups were different (P = 0.02), with the true lumen group having the highest. Also, the difference in BF values between true lumen and false lumen groups was statistically significant (P = 0.016), while no statistical significance was found in the other two groups (P > 0.05). The larger the size of intimal entry tears, the greater the BF values (P = 0.044). Conclusions: This study shows a direct correlation between renal CT perfusion changes and AD, with the size, number of intimal tears, different types of AD, different renal artery origins and false lumen thrombosis, significantly affecting the perfusion values

Influence of MRI-based boundary conditions on type B aortic dissection simulations in false lumen with or without abdominal aorta involvement

Most computational hemodynamic studies of aortic dissections rely on idealized or general boundary conditions. However, numerical simulations that ignore the characteristics of the abdominal branch arteries may not be conducive to accurately observing the hemodynamic changes below the branch arteries. In the present study, two men (M-I and M-II) with type B aortic dissection (TBAD) underwent arterial-phase computed tomography angiography and four-dimensional flow magnetic resonance imaging (MRI) before and after thoracic endovascular aortic repair (TEVAR). The finite element method was used to simulate the computational fluid dynamic parameters of TBAD [false lumen (FL) with or without visceral artery involvement] under MRI-specific and three idealized boundary conditions in one cardiac cycle. Compared to the results of zero pressure and outflow boundary conditions, the simulations with MRI boundary conditions were closer to the initial MRI data. The pressure difference between TL and FL after TEVAR under the other three boundary conditions was lower than that of the MRI-specific results. The results of the outflow boundary conditions could not characterize the effect of the increased wall pressure near the left renal artery caused by the impact of Tear-1, which raised concerns about the distal organ and limb perfused by FL. After TEVAR, the flow velocity and wall pressure in the FL and the distribution areas of high time average wall shear stress and oscillating shear index were reduced. The difference between the calculation results for different boundary conditions was lower in M-II, wherein FL did not involve the abdominal aorta branches than in M-I. The boundary conditions of the abdominal branch arteries from MRI data might be valuable in elucidating the hemodynamic changes of the descending aorta in TBAD patients before and after treatment, especially those with FL involving the branch arteries

Adaptive Neural Control Based on High Order Integral Chained Differentiator for Morphing Aircraft

This paper presents an adaptive neural control for the longitudinal dynamics of a morphing aircraft. Based on the functional decomposition, it is reasonable to decompose the longitudinal dynamics into velocity and altitude subsystems. As for the velocity subsystem, the adaptive control is proposed via dynamic inversion method using neural network. To deal with input constraints, the additional compensation system is employed to help engine recover from input saturation rapidly. The highlight is that high order integral chained differentiator is used to estimate the newly defined variables and an adaptive neural controller is designed for the altitude subsystem where only one neural network is employed to approximate the lumped uncertain nonlinearity. The altitude subsystem controller is considerably simpler than the ones based on backstepping. It is proved using Lyapunov stability theory that the proposed control law can ensure that all the tracking error converges to an arbitrarily small neighborhood around zero. Numerical simulation study demonstrates the effectiveness of the proposed strategy, during the morphing process, in spite of some uncertain system nonlinearity

Prevalence and influencing factors of chronic pain in middle-aged and older adults in China: results of a nationally representative survey

BackgroundWith China's rapidly aging population, chronic pain has become a major public health issue. This article aims at determining associations between chronic pain and multiple factors, including demographic characteristics, health status, and health service utilization of middle-aged and older adults in China.MethodsWe selected all the 19,829 respondents who were over 45 years old from the China Health and Aging Tracking Survey 2018 (CHARLS) as our study population. The key information in terms of the body pain, demographic characteristics, health status, behaviors and health services use was extracted and analyzed. Logistic regression model was used to determine the influencing factors of chronic pain.ResultsAnalysis revealed that 60.02% (9,257) of the data from this survey reported physical pain, with pain sites concentrated at the head (40.9%), lower back (62.2%) and knees (47.2%). Pain was positively associated with influencing factors for pain: being a female (OR = 2.10, 95% CI 1.90–2.33, p &lt; 0.001), living in a western region (OR = 1.28, 95% CI 1.16–1.41, p &lt; 0.001), living in a rural area (OR = 1.14, 95% CI 1.06–1.23, p &lt; 0.001), smoked (OR = 1.26, 95% CI 1.14–1.38, p &lt; 0.001), drank alcohol (OR = 1.16, 95% CI 1.06–1.26, p = 0.001), and had poor self-rated health (OR = 6.84, 95% CI 5.41–8.65, p &lt; 0.001), had hearing problems (OR = 1.23, 95% CI 1.11–3.37, p &lt; 0.001), were depressed (OR = 1.56, 95% CI 1.03–1.29, p &lt; 0.001), had arthritis (OR = 2.21, 95% CI 2.02–2.41, p &lt; 0.001), stomach disorders (OR = 1.69, 95% CI 1.55–1.85, p &lt; 0.001), visited a Western medicine hospital (OR = 1.28, 95% CI 1.10–1.50, p = 0.002), and visits to other medical institutions (OR = 1.42, 95%CI 1.22–1.64, p &lt; 0.001). On the other side, as a protective factor for pain, having nighttime sleep ≥7 h (OR = 0.74, 95%CI 0.68–0.80, p &lt; 0.001) was negatively associated with pain.ConclusionPhysical pain affects many older adults. Women, regional, rural residents, smokers, alcohol drinkers, people with poor self-rated health, those having &lt;7 h of sleep at night, those with hearing problems, depression, arthritis, stomach disorders, and people who visits Western hospitals or other medical institutions are at greater risk for pain and deserve the attention of health care providers and policy makers to focus on pain prevention and management in middle-aged and older adults. Future research studies should also focus on the impact of health literacy on pain prevention and management outcomes