Impact of homocysteine on acute ischemic stroke severity: possible role of aminothiols redox status.

BACKGROUND: Acute ischemic stroke (AIS) is one of the most common cerebrovascular diseases which accompanied by a disruption of aminothiols homeostasis. To explore the relationship of aminothiols with neurologic impairment severity, we investigated four aminothiols, homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CG) and glutathione (GSH) in plasma and its influence on ischemic stroke severity in AIS patients. METHODS: A total of 150 clinical samples from AIS patients were selected for our study. The concentrations of free reduced Hcy (Hcy), own oxidized Hcy (HHcy), free reduced Cys (Cys), own oxidized Cys (cysteine, Cyss), free reduced CG (CG) and free reduced GSH (GSH) were measured by our previously developed hollow fiber centrifugal ultrafiltration (HFCF-UF) method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The concentration ratio of Hcy to HHcy (Hcy/HHcy), Cys to Cyss (Cys/Cyss) were also calculated. The neurologic impairment severity of AIS was evaluated using National Institutes of Health Stroke Scale (NIHSS). The Spearman correlation coefficient and logistic regression analysis was used to estimate and perform the correlation between Hcy, HHcy, Cys, Cyss, CG, GSH, Hcy/HHcy, Cys/Cyss and total Hcy with NIHSS score. RESULTS: The reduced Hcy and Hcy/HHcy was both negatively correlated with NIHSS score in AIS patients with P = 0.008, r=-0.215 and P = 0.002, r=-0.249, respectively. There was no significant correlation of Cys, CG, GSH, HHcy, Cyss, Cys/Cyss and total Hcy with NIHSS score in AIS patients with P value > 0.05. CONCLUSIONS: The reduced Hcy and Hcy/HHcy, not total Hcy concentration should be used to evaluate neurologic impairment severity of AIS patient.

Multiple Scattering from Electrospun Nanofibers with Embedded Silver Nanoparticles of Tunable Shape for Random Lasers and White-Light-Emitting Diodes.

Random lasers (RLs) are convenient, tunable, and widely applicable. However, the influence of fluorescence lifetime on the scattering and nanofiber distribution of nanofibers with various shapes of silver nanoparticles (Ag NPs) embedded within is unclear. We prepared poly(vinyl alcohol) (PVA) nanofibers with Ag NPs through electrospinning (ES) and pyrromethene 597 dye doping. We determined the influences of the particles on scattering enhancement and localized surface plasmon resonance (LSPR) in RLs. The distinct scattering rates and LSPR can be used to control optical properties for sensing devices and other applications. Compared with traditional films, the threshold of the nanofibers with Ag NPs is 35% lower. In addition to improved matching between the LSPR and emission spectra, enhanced coupling of the electric field with nonradiative energy amplifies the radiative emission. Furthermore, the luminescence lifetime shortened by increasing the scattering rate. An excessive scattering rate may accelerate radiative recombination and convert some recombination into nonradiative recombination to produce a more sensitive device. Finally, we applied the prepared nanofibers to a backlight display and fabricated a white-light-emitting diode (LED) with a distinct thickness of nanofibers. The fabricated device is suitable for application in other LEDs and RL devices.

Automated Dual-Chamber Sampling System to Follow Dynamics of Volatile Organic Compounds Emitted by Biological Specimens.

Growth of microorganisms is often accompanied by the release of volatile organic compounds (VOCs). The released VOCs may qualitatively or quantitatively reflect the physiological states of microbial cultures. A number of VOCs are produced during microbial degradation of organic matter accompanying food spoilage. In order to characterize the dynamics of microbial VOC production, and enable time-dependent analysis, we have constructed a dual-chamber sampling system and coupled it online with mass spectrometry (MS). The biological specimen is placed in a gas-tight sampling chamber. A carrier gas is introduced to the chamber periodically to transfer the VOCs present in the specimen headspace to the atmospheric-pressure chemical-ionization interface of a triple-quadrupole mass spectrometer. A control or blank spectrum is recorded before the specimen spectrum is recorded at each time point, enabling signal comparison and subtraction. The custom-made electronic control unit, incorporating three Arduino microcontrollers, operates six pinch valves and a miniature air compressor and triggers MS-data acquisition. The automated dual-chamber sampling system was first tested using standard mixtures to verify its analytical performance. To demonstrate the usefulness of this system in the studies of microbial volatomes, we implemented it in real-time monitoring of the growth of baker's yeast ( Saccharomyces cerevisiae), fructification of golden oyster mushroom ( Pleurotus citrinopileatus), and microbial degradation of a food-related sample (Pacific white shrimp, Litopenaeus vannamei). The recorded VOC signals show characteristic temporal profiles with transient bands or plateaus corresponding to different stages of microbial growth and putrefaction processes.

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry.

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Fizzy Extraction of Volatile and Semivolatile Compounds into the Gas Phase.

Extraction of volatile and semivolatile compounds from liquid matrixes with high yields, and transferring the extracts to detectors in real time, is challenging. Common extraction procedures involve heating the samples to release the analytes to the gas phase and, in some cases, trapping the gas-phase analytes into sorbents or containers. Here, we propose a new method for fast extraction of volatile and semivolatile compounds from liquid matrixes. This method involves dissolution of a carrier gas in the liquid sample by applying a moderate overpressure (∼150 kPa) and stirring the sample. An abrupt decompression of the extraction chamber leads to effervescence. In this step, many bubbles are instantly formed in the sample matrix. The dissolved carrier gas as well as dissolved volatiles are liberated into the headspace of the extraction chamber within a short period of time (few seconds). The gaseous effluent of the extraction chamber is immediately transferred to the online detector; in this case, an atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The fast release of the gas-phase extract gives rise to a high signal recorded by the detector; several times higher than the signal recorded during direct infusion of headspace vapors without fizzy extraction. This feature provides the means to detect and quantify analytes present in solutions in a short period of time. Here we show that fizzy extraction is suitable for analysis of volatile/semivolatile compounds present in various samples, including those containing complex matrixes.

Intelligent Computation for Optimal Fabrication Condition of a Protein Chip with Ni-Co Alloy-Coated Surface.

Based on the principle of immobilized metal affinity chromatography (IMAC), it has been found that a Ni-Co alloy-coated protein chip is able to immobilize functional proteins with a His-tag attached. In this study, an intelligent computational approach was developed to promote the performance and repeatability of a Ni-Co alloy-coated protein chip. This approach was launched out of L18 experiments. Based on the experimental data, the fabrication process model of a Ni-Co protein chip was established by using an artificial neural network, and then an optimal fabrication condition was obtained using the Taguchi genetic algorithm. The result was validated experimentally and compared with a nitrocellulose chip. Consequentially, experimental outcomes revealed that the Ni-Co alloy-coated chip, fabricated using the proposed approach, had the best performance and repeatability compared with the Ni-Co chips of an L18 orthogonal array design and the nitrocellulose chip. Moreover, the low fluorescent background of the chip surface gives a more precise fluorescent detection. Based on a small quantity of experiments, this proposed intelligent computation approach can significantly reduce the experimental cost and improve the product's quality.

Influence of material properties upon immobilization of histidine-tagged protein on Ni-Co coated chip.

In protein research, protein microarray facilitates high-throughput study of protein abundance and function. An appropriate microarray surface that can be used to immobilize protein samples is a prerequisite for the investigation of molecular interactions. Ni-Co alloy coated protein microarray chip has been found to adsorb histidine-tagged proteins effectively based on the method of immobilized metal affinity chromatography. Due to the ingredient of bi-metallic elements, different electroplating conditions resulted in distinct binding affinities. Therefore, the influence of Ni-Co material properties on the immobilization of histidine-tagged protein was systematically investigated in this study. In the experiments, the contact angle measurement suggested that no strong relationship can be established between the wettability of chip surface and its corresponding protein immobilization. ESCA test demonstrated that the major ingredients of the Ni-Co alloy coated protein microarray chip were Ni and Co. In addition, the XRD test concluded that a Ni-Co protein chip that consists mostly of hcp lattice has better binding capability. SEM micrographs provide direct image evidence. These material tests summarize that the Ni-Co alloy coated protein microarray chip adsorbs His-tagged proteins through its surface morphology. Therefore, it can provide specific binding due to the affinity adsorption between the intermediate metals and the protein.

Protein microarray chip with Ni-Co alloy coated surface.

Most protein microarrays based on the theory of immobilized metal affinity chromatography (IMAC) were fabricated using the chelator or compound of mono-metallic ion, such as Ni(2+), to capture the histidine-tagged protein. In this study, a novel protein chip with Ni-Co alloy layer fabricated on the substrate of printed circuit board by electrodeposition was developed. It is an innovative microarray surface with bi-metallic elements, i.e. by means of adding cobalt to enhance the specific binding capability to immobilize functional proteins with His-tag attached. Taguchi method was adopted to determine the optimal electrodeposition condition using L18 orthogonal array. Then, the immunoassay was utilized to investigate the properties of the protein chip, and the signal was detected by confocal scanner. The results show that the alloy coating belongs to codeposition of Ni-Co alloy. Due to the affinity adsorption between intermediate metal and protein, this chip provides specific binding. Compared with Ni-coated chip and nitrocellulose (NC) chip, this Ni-Co alloy chip is a high sensitive protein microarray because of high detected fluorescence intensity with low fluorescent background. The proportion of Ni-Co composition will affect the affinity of electroplated layer with proteins and, consequentially, influence the results of immunoassay. Moreover, the test of long-term sensibility of Ni-Co chip showed that it had better binding capability in the first two weeks for coating buffers of pH 7.4 and pH 9 and the immobilization ability began to decay after the third week. The advantages of this novel protein chip include good performance, high repeatability, and inexpensive.

Dividable membrane with multi-reaction wells for microarray biochips.

This paper presents a multi-well membrane fabricated using polydimethylsiloxane (PDMS) as a part of a microarray biochip that allows dividable incubation chambers to be provided on a single chip. The conditions of the forming temperature, time, and mixing proportion of the materials were investigated to obtain optimal physical absorption with the surface of the chip substrate. To verify the properties of the multi-well chip, immunoassays were performed by the alpha-1-fetoprotein (AFP) antigen sandwich experiment. The results showed that the detection limit reached to the concentration of 10 ng/ml AFP antigen, and that the dynamic range was 30-3000 ng/ml. Attaining excellent physical absorption helps in avoiding cross-contamination or interference between different samples on the same biochip. The merits of dividable multi-well chips include promoting effective use of surface and multiple-sample experiments.

Hydroxylation and glucosidation of ent-16beta-Hydroxybeyeran-19-oic acid by Bacillus megaterium and Aspergillus niger.

ent-16beta-Hydroxybeyeran-19-oic acid ( 1) has potential antihypertensive activity. To obtain novel and more-effective compounds, 1 was incubated with Bacillus megaterium ATCC 14 581 and Aspergillus niger CCRC 32 720. The structures of the metabolites were determined by HR-FAB-MS, 1D- and 2D-NMR spectral data, and enzymatic hydrolysis. Bacillus megaterium hydroxylated and glucosidated 1 to yield ent-7alpha,16beta-dihydroxybeyeran-19-oic acid ( 2), ent-16beta-hydroxybeyeran-19-oic acid alpha- D-glucopyranosyl ester ( 3), and ent-7alpha,16beta-dihydroxybeyeran-19-oic acid alpha- D-glucopyranosyl ester ( 4). Aspergillus niger hydroxylated 1 to yield ent-1beta,7alpha,16beta-trihydroxybeyeran-19-oic acid ( 5) and ent-1beta,7alpha-dihydroxy-16-oxobeyeran-19-oic acid ( 6). Metabolites 3 - 5 were characterized as new compounds. In addition, 2, 3, 5, and 6 were tested for antihypertensive effects, and we found that 5 and 6 were more potent than the parent compound 1.