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Articles by Qingjun Wang in JoVE
JoVE General
MALDI הכנה לדוגמא: שיטת אולטרה שכבה דקה
Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University
וידאו זה מדגים את הכנת שכבת מטריצה / אנליטי דקים לניתוח פפטידים וחלבונים על ידי מטריקס בסיוע לייזר desorption Ionization המוניים ספקטרומטריית (MALDI-MS).
Other articles by Qingjun Wang on PubMed
Proteomic Analysis of a Highly Active Photosystem II Preparation from the Cyanobacterium Synechocystis Sp. PCC 6803 Reveals the Presence of Novel Polypeptides
A highly active oxygen-evolving photosystem II (PSII) complex was purified from the HT-3 strain of the widely used cyanobacterium Synechocystis sp. PCC 6803, in which the CP47 polypeptide has been genetically engineered to contain a polyhistidine tag at its carboxyl terminus [Bricker, T. M., Morvant, J., Masri, N., Sutton, H. M., and Frankel, L. K. (1998) Biochim. Biophys. Acta 1409, 50-57]. These purified PSII centers had four manganese atoms, one calcium atom, and two cytochrome b(559) hemes each. Optical absorption and fluorescence emission spectroscopy as well as western immunoblot analysis demonstrated that the purified PSII preparation was devoid of any contamination with photosystem I and phycobiliproteins. A comprehensive proteomic analysis using a system designed to enhance resolution of low-molecular-weight polypeptides, followed by MALDI mass spectrometry and N-terminal amino acid sequencing, identified 31 distinct polypeptides in this PSII preparation. We propose a new nomenclature for the polypeptide components of PSII identified after PsbZ, which proceeds sequentially from Psb27. During this study, the polypeptides PsbJ, PsbM, PsbX, PsbY, PsbZ, Psb27, and Psb28 proteins were detected for the first time in a purified PSII complex from Synechocystis 6803. Five novel polypeptides were also identified in this preparation. They included the Sll1638 protein, which shares significant sequence similarity to PsbQ, a peripheral protein of PSII that was previously thought to be present only in chloroplasts. This work describes newly identified proteins in a highly purified cyanobacterial PSII preparation that is being widely used to investigate the structure, function, and biogenesis of this photosystem.
A Facile Dip-coating Process for Preparing Highly Durable Superhydrophobic Surface with Multi-scale Structures on Paint Films
Superhydrophobic surfaces with multi-scale nano/microstructures have been prepared on epoxy paint surfaces using a feasible dip-coating process. The microstructures with 5-10 microm protuberances were first prepared on epoxy paint surface by sandblast. Then the nanostructures were introduced on the microstructure surface by anchoring 50-100 nm SiO(2) particles (nano-SiO(2)) onto the sandblasted paint surface, which was completed by dip-coating with a nano-SiO(2)/epoxy adhesive solution (M1). At last the surface was further modified for enhancing hydrophobicity by another dip-coating with a solution of a low surface energy polymer, aminopropyl terminated polydimethylsiloxane (ATPS) modified epoxy adhesive (M2). The water contact angle of the as-prepared samples reached as high as 167.8 degrees and the sliding angle was 7 degrees. The prepared superhydrophobic surface exhibited excellent durability to the high speed scouring test and high stability in neutral and basic aqueous solutions and some common organic solvents. In addition, this method can be adopted to fabricate large scale samples with a good homogeneity of the whole surface at very low cost.
Minimization of MR Contrast Weightings for the Comprehensive Evaluation of Carotid Atherosclerotic Disease
Multicontrast, high-resolution carotid magnetic resonance imaging (MRI) has been validated with histology to quantify atherosclerotic plaque morphology and composition. For evaluating the lipid-rich necrotic core (LRNC) and fibrous cap, both of which are key elements in determining plaque stability, the combined pre- and postcontrast T1-weighted (T1W) sequences have been recently shown to have a higher reproducibility than other contrast weightings. In this study, we sought to determine whether contrast weightings beyond T1W (pre- and postcontrast) are necessary for comprehensive, quantitative, carotid plaque interpretation.
High-resolution MR Study of the Relationship Between Superficial Calcification and the Stability of Carotid Atherosclerotic Plaque
In this study, we have aimed to evaluate the relationship between the shape and location of superficial calcification and the presence of fibrous cap rupture and intraplaque hemorrhage in atherosclerotic carotid plaque. Sixty-three patients with carotid stenosis underwent contrast-enhanced high resolution MR examinations with a 3-T MR scanner and 226 slices with superficial calcification were evaluated in the study. The shape of superficial calcification was categorized as the irregular type (dotted/arcuated) and patchy type and the location of superficial calcification was categorized as the marginal type and central type. Intraplaque hemorrhage and fibrous cap rupture depicted on the same slice as superficial calcification were identified. The chi-squared test was used for statistical analysis. A total of 149 slices (65.9%) with intraplaque hemorrhage and 107 slices(47.3%)with fibrous cap rupture were detected. There were 191 slices with irregular type (dotted/arcuated) calcification and 166 slices with marginal type calcification. Irregular superficial calcification was found more frequently accompanied with intraplaque hemorrhage as compared to the patchy type (73.8 vs. 22.9%, P < 0.0001); there was a significant difference between the marginal type and the central type for the accompaniment of intraplaque hemorrhage (72.9 vs. 46.7%, P < 0.05). However, there was no significant difference between different shapes and locations of superficial calcification that accompanied with fibrous cap rupture (P > 0.05). This study showed that superficial calcification is an important factor for determination of instability of atherosclerotic carotid plaque. The shape and location of superficial calcification are important features associated with the occurrence of intraplaque hemorrhage.
Differences of Signal Evolution of Intraplaque Hemorrhage and Associated Stenosis Between Symptomatic and Asymptomatic Atherosclerotic Carotid Arteries: an in Vivo High-resolution Magnetic Resonance Imaging Follow-up Study
To evaluate the differences of signal evolution of intraplaque hemorrhage (IPH) and associated stenosis between symptomatic and asymptomatic atherosclerotic carotid arteries. Thirty-three carotid arteries (15 symptomatic and 18 asymptomatic plaques) with recent carotid IPH underwent serial high-resolution MRI examinations on a 3.0-Tesla (3.0T) MRI scanner over a period of 18 months. MR sequences included three-dimensional time-of-flight (3D-TOF), quadruple-inversion-recovery T1-weighted imaging (QIR T1 WI), proton density-weighted imaging (PDWI), and T2-weighted imaging (T2WI). The contrast-to-noise ratios (CNRs) of subsequent IPH during the follow-up period between symptomatic and asymptomatic carotid IPH showed a significant difference on 3D-TOF (P = 0.029), T1 WI (P = 0.005), and PDWI (P = 0.028), except for that on T2WI (P = 0.362). Compared with no significant signal intensity change of symptomatic IPH, CNRs of asymptomatic IPH exhibited a gradually descending trend on all contrast weighted images (P < 0.05). Compared with asymptomatic arteries, the degree of diameter stenosis associated with IPH increased significantly in the symptomatic atherosclerotic carotid arteries between baseline and the 18th month (10.53 ± 12.29% vs. 1.65 ± 7.74%, P = 0.017). Symptomatic and asymptomatic carotid IPH demonstrated different MRI signal evolution and associated carotid stenosis. Repeated carotid IPH may be more common in symptomatic plaques than in asymptomatic plaques and might produce a stronger stimulus for progression of atherosclerosis than one-time carotid IPH.
Superhydrophobicity of Natural and Artificial Surfaces Under Controlled Condensation Conditions
In this paper, we have comparatively investigated the stability of superhydrophobic behaviors of fresh and biomimetic lotus leaf surfaces under controlled water condensation conditions. The binary micro/nano structures of the superhydrophobic surfaces are observed with electron micrographs. Contact and sliding angles are evaluated by syringing water droplets on the substrates with surface temperatures and humidity precisely controlled between -10 and 30 °C, and RH = 10, 30, 60, and 90%. According to the calculations on the solid-liquid contact area fraction in different environmental conditions based on a micro/nano binary structure model, the effects of condensed water on superhydrophobic surfaces are assessed quantitatively. Both the calculated and experimental results indicate that the temperature difference between surface temperature and the dew point during measurement is essential to the occurrence of water condensation while the effect of condensation on the surface wettability also depends on the topology of hierarchical structured surfaces. The loss of water repellency that usually appears on the artificial superhydrophobic surface under low temperature and high humidity conditions is proved to be reversible, showing a bidirectional transition of the equilibrium state between Wenzel and Cassie-Baxter.
Comparison of Carotid Arterial Morphology and Plaque Composition Between Patients with Acute Coronary Syndrome and Stable Coronary Artery Disease: a High-resolution Magnetic Resonance Imaging Study
The purpose of this study was to evaluate the differences in carotid arterial morphology and plaque composition between patients with acute coronary syndrome (ACS) and patients with stable coronary artery disease (SCAD). Twenty-eight patients (12 ACS patients and 16 SCAD patients) underwent carotid high-resolution MRI examination using a 3.0-Tesla (3.0T) MRI scanner. The indicators of carotid arterial morphology included the maximum total vessel area (Max-TVA), mean TVA, minimum lumen area (Min-LA), mean LA, maximum wall area (Max-WA), mean WA, maximum wall thickness (Max-WT), mean WT, maximum normalized wall index (Max-NWI), mean NWI, and maximum stenosis (Max-stenosis). The indicators of plaque composition included the prevalence and mean area percentage (%) of lipid-rich necrotic core (LRNC), calcification (Ca), intraplaque hemorrhage (IPH), and fibrous cap rupture (FCR). None of the indicators of carotid arterial morphology had significant differences (all P > 0.05) between the ACS and SCAD patients. The prevalence and plaque composition area percentage of LRNC, Ca, and IPH did not exhibit significant differences between the two groups. However, carotid plaques in the ACS patients presented a higher prevalence of FCR than SCAD patients (P < 0.05). This study revealed a similar carotid arterial morphology between ACS and SCAD patients. However, FCR is more common in carotid plaques with ACS than in those with SCAD. Ruptured carotid plaques may be a forewarning factor for those patients who are at high risk of ACS.
