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《Endocrine practice》2019,25(11):1233-1234
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Background
Carbon dioxide (CO2) is a recognized vasodilator of myocardial blood vessels that leads to changes in myocardial oxygenation through the recruitment of the coronary flow reserve. Yet, it is unknown whether changes of carbon dioxide induced by breathing maneuvers can be used to modify coronary blood flow and thus myocardial oxygenation. Oxygenation-sensitive cardiovascular magnetic resonance (CMR) using the blood oxygen level-dependent (BOLD) effect allows for non-invasive monitoring of changes of myocardial tissue oxygenation. We hypothesized that mild hypercapnia induced by long breath-holds leads to changes in myocardial oxygenation that can be detected by oxygenation-sensitive CMR.Methods and Results
In nine anaesthetized and ventilated pigs, 60s breath-holds were induced. Left ventricular myocardial and blood pool oxygenation changes, as monitored by oxygenation-sensitive CMR using a T2*-weighted steady-state-free-precession (SSFP) sequence at 1.5T, were compared to changes of blood gas levels obtained immediately prior to and after the breath-hold. Long breath-holds resulted in an increase of paCO2, accompanied by a decrease of paO2 and pH. There was a significant decrease of blood pressure, while heart rate did not change. A decrease in the left ventricular blood pool oxygenation was observed, which was similar to drop in SaO2. Oxygenation in the myocardial tissue however, was maintained throughout the period. Changes in myocardial oxygenation were strongly correlated with the change in paCO2 during the breath-hold (r = 0.90, p = 0.010).Conclusion
Despite a drop in blood oxygen levels, myocardial oxygenation is maintained throughout long breath-holds and is linearly correlated with the parallel increase of arterial CO2, a known coronary vasodilator. Breathing maneuvers in combination with oxygenation-sensitive CMR may be useful as a diagnostic test for coronary artery function. 相似文献3.
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Kenthorai Raman Jegannathan Sariah Abang Denis Poncelet Eng Seng Chan 《Critical reviews in biotechnology》2013,33(4):253-264
Increase in volume of biodiesel production in the world scenario proves that biodiesel is accepted as an alternative to conventional fuel. Production of biodiesel using alkaline catalyst has been commercially implemented due to its high conversion and low production time. For the product and process development of biodiesel, enzymatic transesterification has been suggested to produce a high purity product with an economic, environment friendly process at mild reaction conditions. The enzyme cost being the main hurdle can be overcome by immobilization. Immobilized enzyme, which has been successfully used in various fields over the soluble counterpart, could be employed in biodiesel production with the aim of reducing the production cost by reusing the enzyme. This review attempts to provide an updated compilation of the studies reported on biodiesel production by using lipase immobilized through various techniques and the parameters, which affect their functionality. 相似文献
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Grinevich A. A. Gharamyan B. G. Chemeris N. K. 《Doklady. Biochemistry and biophysics》2022,504(1):118-122
Doklady Biochemistry and Biophysics - Peripheral blood flow analysis is used for noninvasive assessment of the cardiovascular system. The aim was to investigate the possibility of applying... 相似文献
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Synthesis of Silver Nanoparticles Using Callus Extract of Carica papaya — A First Report 总被引:1,自引:0,他引:1
Namrata Mude Avinash Ingle Aniket Gade Mahendra Rai 《Journal of plant biochemistry and biotechnology.》2009,18(1):83-86
This is the first report of synthesis of silver nanoparticles by using callus extract of Carica papaya. MS medium supplemented with the growth hormones, 2.0 mg l?1 IBA and 0.5 mg l?1 BAP was found to be more suitable for the induction of callus and multiple shoots in papaya. The extract of callus obtained by grinding showed ability of synthesis of silver nanoparticles when treated with silver nitrate (1 mM). The formation of brown colour in the reaction mixture indicates the synthesis of silver nanoparticles. The further detection and characterization of these synthesized silver nanoparticles was carried by spectrophotometry. FTIR spectrum analysis showed peaks between 1000–2000 cm?1 which confirmed the presence of proteins and other ligands required for the synthesis and stabilization of silver nanoparticles. SEM micrograph confirmed the synthesis of spherical silver nanoparticles in the size range of 60–80 nm. 相似文献
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Susan A. Crate 《Human ecology: an interdisciplinary journal》2003,31(4):499-528
The Sakha of northeastern Siberia, Russia, are the highest latitude contemporary agropastoralists practicing horse and cattle husbandry. In the last 100 years their rural livelihood has gone from household-level subsistence food production in clan clusters of single-family homesteads scattered across the landscape, to village-level state agribusiness farm production in compact settlements dependent on Soviet socialist infrastructure, to the present-day post-socialist reliance on household-level subsistence food production. This paper explores how Viliui Sakha are adapting in the post-Soviet context. Since the fall of the Soviet Union and the concomitant dissolution of the centralized state farm system, rural inhabitants have developed household and interhousehold food production capacities based on keeping cows and relying on exchange among kin. One of the basic tenets of Robert Netting's smallholder–householder theory is that in times of change, the household system is the most resilient subsistence production unit because of specific qualities including intimate ecological knowledge and implicit labor contracts. This research shows in what ways Netting's householder theory applies for subarctic agropastoralists. 相似文献
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A. Poison 《Preparative biochemistry & biotechnology》2013,43(1-2):121-126
ABSTRACT A semi-quantitative theory is proposed for the sedimentation of particles in centrifuge tubes filled with polymer beads acting as sedimentation aids. The theory concerns the attainment of approximate sedimentation-diffusion equilibrium in minimum time of centrifiigation. It is shown empirically that the time to reach this state is approximately proportional to the diameter of the polymer beads as predicted by the theory. 相似文献
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Obtaining reliable and valid data on sensitive questions represents a longstanding challenge for public health, particularly HIV research. To overcome the challenge, we assessed a construal level theory (CLT)-based novel method. The method was previously established and pilot-tested using the Brief Sexual Openness Scale (BSOS). This scale consists of five items assessing attitudes toward premarital sex, multiple sexual partners, homosexuality, extramarital sex, and commercial sex, all rated on a standard 5-point Likert scale. In addition to self-assessment, the participants were asked to assess rural residents, urban residents, and foreigners. The self-assessment plus the assessment of the three other groups were all used as subconstructs of one latent construct: sexual openness. The method was validated with data from 1,132 rural-to-urban migrants (mean age = 32.5, SD = 7.9; 49.6% female) recruited in China. Consistent with CLT, the Cronbach alpha of the BSOS as a conventional tool increased with social distance, from .81 for self-assessment to .97 for assessing foreigners. In addition to a satisfactory fit of the data to a one-factor model (CFI = .94, TLI = .93, RMSEA = .08), a common factor was separated from the four perspective factors (i.e., migrants’ self-perspective and their perspectives of rural residents, urban residents and foreigners) through a trifactor modeling analysis (CFI = .95, TLI = .94, RMSEA = .08). Relative to its conventional form, CTL-based BSOS was more reliable (alpha: .96 vs .81) and valid in predicting sexual desire, frequency of dating, age of first sex, multiple sexual partners and STD history. This novel technique can be used to assess sexual openness, and possibly other sensitive questions among Chinese domestic migrants. 相似文献
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Dario Cattaneo Andrea Giacomelli Cristina Gervasoni 《Obesity (Silver Spring, Md.)》2018,26(8):1251-1252
Improved survival achieved by HIV‐infected patients has complicated their medical care, as increasing numbers of comorbidities have led to polypharmacy and a higher risk of drug–drug interactions. Here, evidence is provided that weight‐loss drugs should be used with caution in HIV‐infected patients treated with lipophilic antiretroviral drugs because of the risk of virologic failure. This is particularly relevant considering that these agents are available on the market as over‐the‐counter medications, thus escaping the control of the physician. 相似文献
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Donald R. Pratt 《The Western journal of medicine》1959,91(1):12-15
Successful primary repair of soft tissue injuries of the hand and forearm holds the ultimate disability to a minimum. The kinds of trauma and the resultant soft tissue damage may be classified. Attention to details and technique in carrying out the primary reparative operation on the injured hand largely obviates a crippling deformity or the need for much reconstruction later. 相似文献
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Claudia Geue Olivia Wu Yiqiao Xin Robert Heggie Sharon Hutchinson Natasha K. Martin Elisabeth Fenwick David Goldberg Consortium ECDC 《PloS one》2015,10(12)