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1.
Minjuan Shen Mingli Lin Mengqi Zhu Wenxin Zhang Danyang Lu Huanhuan Liu Jingjing Deng Kehua Que Xu Zhang 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):167-181
Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering. 相似文献
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The purpose of this study was to explore new insights in non-linearity, hysteresis and ventilation heterogeneity of asthmatic human lungs using four-dimensional computed tomography (4D-CT) image data acquired during tidal breathing. Volumetric image data were acquired for 5 non-severe and one severe asthmatic volunteers. Besides 4D-CT image data, function residual capacity and total lung capacity image data during breath-hold were acquired for comparison with dynamic scans. Quantitative results were compared with the previously reported analysis of five healthy human lungs. Using an image registration technique, local variables such as regional ventilation and anisotropic deformation index (ADI) were estimated. Regional ventilation characteristics of non-severe asthmatic subjects were similar to those of healthy subjects, but different from the severe asthmatic subject. Lobar airflow fractions were also well correlated between static and dynamic scans (R2 > 0.84). However, local ventilation heterogeneity significantly increased during tidal breathing in both healthy and asthmatic subjects relative to that of breath-hold perhaps because of airway resistance present only in dynamic breathing. ADI was used to quantify non-linearity and hysteresis of lung motion during tidal breathing. Non-linearity was greater on inhalation than exhalation among all subjects. However, exhalation non-linearity among asthmatic subjects was greater than healthy subjects and the difference diminished during inhalation. An increase of non-linearity during exhalation in asthmatic subjects accounted for lower hysteresis relative to that of healthy ones. Thus, assessment of non-linearity differences between healthy and asthmatic lungs during exhalation may provide quantitative metrics for subject identification and outcome assessment of new interventions. 相似文献
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In the past few decades, major advances in environmental protection within the coating application industry have been made. In spite of this technological progress, approximately 50% of industrial-solvent emissions still come from the paint-application sector. The advances made in reducing emissions for plants requiring licensing have unfortunately had no influence on the environmental efforts of smaller companies. Solvent-reduced painting systems, such as high-solid paints, water-based coating, and powder coating have not been able to achieve acceptance, nor have innovative application technologies. The principal arguments against a conversion to these ecologically more favorable alternatives were related to cost and quality.
Recently, the EU Solvent Directive (1999/13/EC) went into effect, aiming to significantly reduce industrial-solvent emissions. Up until this point, however, instruments enabling smaller companies to determine their solvent emissions and to simultaneously develop process-improvement potentials while keeping costs in mind have been missing.
Using the mass and energy flow-management approach, cost structures and environmental benefits can be made transparent to the entrepreneur. The primary result of the research projects presented here is the computer-based mass and energy flow model called the individual computer-aided mass and energy flow model for the vehicle-refinishing sector (IMPROVE). It can be used as a detailed business-consultancy tool. Based upon this, practical guidelines were developed for easy orientation and activity planning. They can be used by companies to help them fulfill the requirements of environmental legislation and to display the benefits that can be achieved by various emission-reduction measures. 相似文献
Recently, the EU Solvent Directive (1999/13/EC) went into effect, aiming to significantly reduce industrial-solvent emissions. Up until this point, however, instruments enabling smaller companies to determine their solvent emissions and to simultaneously develop process-improvement potentials while keeping costs in mind have been missing.
Using the mass and energy flow-management approach, cost structures and environmental benefits can be made transparent to the entrepreneur. The primary result of the research projects presented here is the computer-based mass and energy flow model called the individual computer-aided mass and energy flow model for the vehicle-refinishing sector (IMPROVE). It can be used as a detailed business-consultancy tool. Based upon this, practical guidelines were developed for easy orientation and activity planning. They can be used by companies to help them fulfill the requirements of environmental legislation and to display the benefits that can be achieved by various emission-reduction measures. 相似文献
6.
A particle-induced X-ray emission (PIXE) analysis method is presented, which allows measurement of eight elements (i.e., K,
Ca, Mn, Fe, Cu, Zn, Se, and Rb) in human brain samples of only a few mg dry weight. The precision and accuracy of the method
were investigated by analyzing animal brain matter with both PIXE and instrumental neutron activation analysis (INAA). The
method was applied to measure the 8 elements in 46 different regions of 3 human brains. The sections analyzed originated from
either the left or the right cerebral hemisphere, brain stem, and cerebellum. For one of the brains, sections were also analyzed
from 26 corresponding regions of both hemispheres. For all elements, similar concentrations were found in the corresponding
areas of the left and right sides of the brain. The concentrations (in μg/g dry weight) of the elements K, Fe, Cu, Zn, Se,
and Rb were consistently higher in cortical structures than in white matter. Deep nuclei and brain stem, which have a mixed
composition, showed intermediate values for K, Zn, Se, and Rb. A hierarchical cluster analysis indicated that the various
brain regions clustered into two large groups, one comprising gray and mixed matter regions and the other, white and mixed
matter brain areas. 相似文献
7.
Carroll D. Arnett Joanna S. Fowler Robert R. MacGregor David J. Schlyer Alfred P. Wolf Bengt Långström Christer Halldin 《Journal of neurochemistry》1987,49(2):522-527
The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, Ki) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well. 相似文献
8.
Studies of the relationship between isoprene emission rate and CO2 or photon-flux density using a real-time isoprene analyser 总被引:1,自引:0,他引:1
Abstract. Studies of the isoprene emission rate in response to changes in photon-flux density and CO2 partial pressure were conducted using a recently developed on-line isoprene analyser combined with a gas exchange system and chlorophyll fluorometer. Upon darkening, the isoprene emission rate from leaves of aspen ( Populus tremuloides Michaux.) began to decline immediately, demonstrating that the internal pool of isoprene, or its precursors, is small and that the instantaneous emission rate is tightly coupled to the rate of synthesis. A post-illumination burst of isoprene was observed within 5 min after darkening and lasted for 15–20 min in four isoprene-emitting species that were examined. In leaves of eucalyptus ( Eucalyptus globulus Labill.), the magnitude of the post-illumination burst was dependent on the photon-flux density that existed before darkening, but not on ambient CO2 partial pressure. The dependence of the post-illumination burst on photon-flux density paralleled that for the steady-state rate of isoprene emission. A step-wise increase in intercellular CO2 partial pressure from 24.5 to 60 Pa resulted in an immediate decrease in isoprene emission rate and non-photochemical fluorescence quenching, but an increase in CO2 assimilation rate. Given the several recent studies that link isoprene emission to chloroplastic processes, the results of this study indicate that the linkage is not dependent on the rate of CO2 flux through the reductive pentose phosphate pathway, but rather on more complex relationships involving metabolites not appreciably influenced by CO2 partial pressure. 相似文献
9.
D R Sumner B Mockbee K Morse T Cram M Pitt 《American journal of physical anthropology》1985,68(2):225-232
Non-invasive characterization of limb bone cross-sectional geometry would be useful for biomechanical analyses of skeletal collections. Computed tomography (CT) is potentially the method of choice. Additionally, CT images are suitable for automated analysis. CT is here shown to be both accurate and precise in the analysis of cross-sectional geometry of prehistoric femora. Beam hardening artifacts can be reduced by using a water bath. As the availability of CT for research increases, both bone density and geometry could be determined simultaneously with this method. 相似文献
10.
Cytochrome c oxidase preparations from bovine heart muscle contain 1 zinc per 2 irons. Metal contents of nine preparations determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) show that Cu, Fe and Zn are the only metals present in significant amounts with average Cu/Fe, Fe/Zn, and Cu/Zn atom ratios of 1.3, 2.1 and 2.8, respectively. Removal of adventitious copper results in a Cu:Fe:Zn stoichiometry of 2:2:1. The zinc is tightly bound. Dialysis against a solution of 1,10-phenanthroline at pH 7.4 or an acidic buffer (pH 4.4) does not remove Zn. Dialysis against 0.8 M KCN at pH 10 causes partial loss of both Cu and Zn. This is the first evidence for the presence of Zn in a cytochrome c oxidase. 相似文献