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Biomedical subjects

Yang Chen

Publications and source records attributed to Yang Chen.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Effects of simulated acid rain on physiological and biochemical characters of eggplant, the host plant of Tetranychus cinnabarinus].

In a series of laboratory trials, this paper studied the responses of eggplant (Solanum melongena), the host plant of carmine spider mite Tetranychus cinnabarinus, to different pH values simulated acid rain. The results showed that with the increasing acidity of simulated acid rain, the CAT activity and the contents of P and soluble protein in egg plant leaves increased significantly first, reaching the highest at pH 4.0 or 3.0, and then decreased; while the POD activity and soluble sugar content were in adverse. The reduced sugar content and SOD activity of eggplant leaves increased, but the pH value decreased with increasing acidity of acid rain. Acid rain had no effect on leaf water content. Among the test indices, leaf POD was most insensitive to the acid rain, followed by leaf pH, SOD and CAT, while the others were very sensitive. Weak acid rain (pH > 4.0) promoted the protective ability of eggplant leaf and its growth, and the growth of T. cinnabarinus was also promoted because of the changed contents of soluble sugar, P and soluble protein in eggplant leaves being more favorable to its eating; while strong acid rain (pH < 3.0) inhibited the growth of both host plant and mite.

Acid Rain↗
PubMed2005

[A preliminary study of the influence of different consonants on the vowel in normal people].

PURPOSE: To study the influence of different consonants on the vowel in normal people for guiding research and treatment of cleft palate misarticulations. METHODS: 35 normal students including 15 males and 20 females were selected for this study. The average age was 20.43 year. The six test syllables were divided into three groups: /si/-/ji/, /bo/-/po/ and /jü/-/qü/. The measured indexes of vowel, which were input into CSL4400, were duration (Dur), pitch, the first three formants (F1, F2, F3) and energy (E). The acoustic features of the vowel of each group were compared by SPSS software with Paired t test. RESULTS: Dur of the vowel was 0.39+/-0.08 in /si/ and 0.31+/-0.07 in /ji/, F2 of the vowel was 2093.55+/-350.62 in /si/ and 2454.33+/-422.00 in /ji/, there was significant difference in Dur and F2 between the vowels of /si/-/ji/ (P<0.01); Dur of the vowel was 0.35+/-0.09 in /bo/ and 0.53+/-0.07 in /po/, E of the vowel was 64.11+/-4.58 in /bo/ and 69.94+/-3.59 in /po/, there was significant difference in Dur and E between the vowels of /bo/-/po/ (P<0.01); Dur of the vowel was 0.29+/-0.07 in /jü/ and 0.35+/-0.09 in /qü/, F3 of the vowel was 3180.30+/-301.72 in /jü/ and 2901.06+/-259.75 in /qü/, E of the vowel was 68.99+/-4.59 in /jü/ and 71.70+/-5.21 in /qü/, there was significant difference in Dur, E and F3 between the vowels of /jü/-/qü/ (P<0.05). CONCLUSIONS: It is suggested that the aspiration of the consonant, the part and the extent of the block of the consonant could affect the next vowel, but couldn't change its quality.

Articulation Disorders↗
PubMed2005

Cloning, expression and characterization of the Ste6 gene encoding a UDP-glucose dehydrogenase in Streptomyces.

Streptomyces sp. 139 was identified to produce a new exopolysaccharide Ebosin (139A) with antirheumatic arthritis activity in vivo. The Ebosin biosynthesis gene cluster(31.3 kb; GenBank Accession Number: AY131229) containing 22 ORFs (ste1-ste22) of Streptomyces sp. 139 had been reported previously. In this paper,we present experimental evidence for the identity of the ste6 gene product as a UDP-glucose dehydrogenase (UDPGDH). With pET-30a as vector,the gene was cloned and expressed in Escherichia coli BL21 (DE3). The expressed protein was purified to homogeneity by His-Bind resin affinity chromatograpy and it was able to catalyze UDP-glucose to UDP-glucuronic acid. To evaluate the function of ste6, the gene was disrupted by a single-crossover homologous recombination event and the result showed that ste6 is required in Ebosin biosynthesis.

Amino Acid Sequence↗
PubMed2005

[Primary study of pharyngeal flap surgery in congenital velopharyngeal insufficiency].

OBJECTIVE: To study effective operation method of congenital velopharyngeal insufficiency by reviewing clinical data of 29 patients with pharyngoplasties. METHODS: 29 patients (9 male and 20 female, ranged from 4 to 25 years old, mean age was 13.5) with congenital velopharyngeal insufficiency were available for this study. All cases received Chinese speech intelligibility test and blowing test before and after the pharyngeal flap surgery. RESULTS: Chinese speech intelligibility of 29 cases who underwent pharyngoplasties was improved from 33.86% to 43.13%, and the blowing time was increased from 4.60 to 17.72 seconds, the degree of abnormal speech was reduced. CONCLUSION: The pharyngeal flap surgery is an effective method for congenital velopharyngeal insufficiency, which reduces hypernasality and increases oral pressure, improves the velopharyngeal function.

Female↗
PubMed2005

[Root growth characteristics of soybean and Faba bean at their seedling stage].

Soybean and faba bean are the two main legumes widely intercropped with cereals (e. g., wheat or maize) in western China, but have significantly different performance in intercropping system. Compared to soybean, faba bean has a stronger competitive ability. Considering that underground interspecific interaction makes a significant contribution to the advantage of intercropping system, a pot experiment was conducted to compare the differences in root growth and morphological parameters between soybean and faba bean at their seedling stage. A PVC tube, with 10 cm in diameter and 50 cm in depth, was filled with quartz and used to grow the crops. Root systems were scanned by a scanner, and analyzed by WinRHIZO on days 14, 21, 28, 35 and 42 after seedling emergence. The results indicated that on the 42nd day after seedling emergence, the root surface area of faba bean was 2.61 times larger than that of soybean. Soybean roots distributed in the whole layer of quartz on the 14th day, but most faba bean roots only distributed in its top layer. Soybean roots were thinner, and most of them were 0.25 approximately 1.0 mm in diameter, while faba bean roots were thicker, and their diameter was mostly between 0.5 approximately 1.5 mm. All of these facts resulted in a higher absorption capacity and nutrient use efficiency of faba bean, which could be one of the reasons that faba bean had a stronger competitive capacity than soybean.

Plant Roots↗
PubMed2004

Entrapment of Src protein tyrosine kinase in sugar-modified silica.

A novel sugar-modified silica has been used to entrap for the first time a protein tyrosine kinase (PTK). Silane precursors bearing covalently attached gluconamide moieties were used in combination with the biocompatible precursor diglycerylsilane (DGS) to generate sol-gel derived silica that was able to encapsulate highly active Src PTK and preserve the activity of the enzyme over multiple uses. The relative activity of the enzyme was assayed using a LANCE based fluorescence resonance energy transfer method involving time-gated detection of fluorescence from a europium labeled antiphosphotyrosine antibody and Cy5 labeled streptavidin upon mutual binding to biotinylated phosphopeptides. Using this detection method, with the antibody and streptavidin external to the sol-gel matrix, it was possible to detect the phosphorylation of peptides with molecular weights of up to 2300 Da using the entrapped enzyme in N-(3-triethoxysilylpropyl)gluconamide (GLTES) doped glasses. Src kinase-doped glasses, derived from precursors such as tetramethyl orthosilicate, tetraethyl orthosilicate, or DGS that did not contain GLTES, provided no detectable enzyme activity. The addition of 1 mM ATP to the GLTES/DGS sol before the encapsulation of the protein increased the activity of the enzyme in the resulting gel, likely through a ligand-based stabilization mechanism. The use of such a system for determination of PTK activity and inhibition is demonstrated, setting the stage for the development of chromatographic and microarray based methods for the screening of kinase inhibitors.

Fluorescence↗
PubMed2004

Evaluating formation and growth mechanisms of silica particles using fluorescence anisotropy decay analysis.

At present, there is no direct experimental evidence that primary silica particles, which exist only transiently for a few seconds during the Stöber silica synthesis, can be stable in aqueous solutions. In the present work, we show that primary silica particles are formed spontaneously after the dissolution of diglycerylsilane (DGS) in aqueous solutions and remain stable for prolonged periods of time. By using time-resolved fluorescence anisotropy (TRFA), we demonstrate that this unique property of DGS is ascribed to the slow kinetics of silica particle growth in diluted sols at pH approximately 9.0. The anisotropy decay of the cationic dye rhodamine 6G (R6G), which strongly adsorbs to silica oligomers and nanoparticles in DGS sols, could be fit to three components: a fast (picosecond) scale component associated with free R6G, a slower (nanosecond) rotational component associated with R6G bound to primary silica particles, and a residual (nondecaying) anisotropy component associated with R6G that was bound to secondary or larger particles that were unable to rotate on the time scale of the R6G emission lifetime (4 ns). The data show that, under conditions where fast hydrolysis is obtained, the initial size of the nuclei depends on the silica concentration, with larger nuclei being present in more concentrated sols, while the rate of growth of primary particles depends on both silica concentration and solution pH. At low silica concentrations and high pHs, it was possible to observe the growth of stable, nonaggregating primary silica particles by a mechanism involving rapid nucleation followed by monomer addition. The presence of stable primary particles was confirmed by atomic force microscopy (AFM) imaging. At higher silica concentrations and lower pHs, there was an increase in the initial size of the nuclei formed, which subsequently grew to a larger radius (> 4.5 nm) or aggregated with time, and in such cases, nucleation and aggregation occurred simultaneously in the early stage of silica formation. The data clearly show the power of time-resolved fluorescence anisotropy decay measurements for probing the growth of silica colloids and show that this method is useful for elucidating the mechanism of particle formation and growth in situ.

Journal Article↗
PubMed2004

Ultrasensitive ATP detection using firefly luciferase entrapped in sugar-modified sol-gel-derived silica.

Firefly luciferase (FL) was entrapped in sol-gel-derived silica containing precursors based on covalent linkage of d-gluconolactone or d-maltonolactone to (aminopropyl)triethoxysilane to form N-(3-triethoxysilylpropyl)gluconamide or N-(3-triethoxysilylpropyl)maltonamide. The enzyme was active and stable in this material and showed catalytic constants close to those in solution. As little as 20 amol ATP could be detected with the entrapped FL, and the entrapped enzyme could be used over several cycles.

Adenosine Triphosphate↗
PubMed2004

Protein-doped monolithic silica columns for capillary liquid chromatography prepared by the sol-gel method: applications to frontal affinity chromatography.

The development of bioaffinity chromatography columns that are based on the entrapment of biomolecules within the pores of sol-gel-derived monolithic silica is reported. Monolithic nanoflow columns are formed by mixing the protein-compatible silica precursor diglycerylsilane with a buffered aqueous solution containing poly(ethylene oxide) (PEO, MW 10,000) and the protein of interest and then loading this mixture into a fused-silica capillary (150-250-microm i.d.). Spinodal decomposition of the PEO-doped sol into two distinct phases prior to the gelation of the silica results in a bimodal pore distribution that produces large macropores (>0.1 microm), to allow good flow of eluent with minimal back pressure, and mesopores (approximately 3-5-nm diameter) that retain a significant fraction of the entrapped protein. Addition of low levels of (3-aminopropyl)triethoxysilane is shown to minimize nonselective interactions of analytes with the column material, resulting in a column that is able to retain small molecules by virtue of their interaction with the entrapped biomolecules. Such columns are shown to be suitable for pressure-driven liquid chromatography and can be operated at relatively high flow rates (up to 500 microL x min(-1)) or with low back pressures (<100 psi) when used at flow rates of 5-10 microL x min(-1). The clinically relevant enzyme dihydrofolate reductase was entrapped within the bioaffinity columns and was used to screen mixtures of small molecules using frontal affinity chromatography with mass spectrometric detection. Inhibitors present in compound mixtures were retained via bioaffinity interactions, with the retention time being dependent on both the ligand concentration and the affinity of the ligand for the protein. The results suggest that such columns may find use in high-throughput screening of compound mixtures.

Buffers↗
PubMed2004

Fluorescence anisotropy in studies of solute interactions with covalently modified colloidal silica nanoparticles.

Time-resolved anisotropy decays of a fluorescent cationic solute, rhodamine 6G (R6G), in Ludox sols were measured to characterize the extent of the ionic binding of the probe to silica particles after modification of the surface with neutral or cationic silane coupling agents. The anisotropy decays provided direct evidence for distribution of the dye between the aqueous solution (picosecond decay component) and silica particles (nanosecond decay component and residual anisotropy component, which were attributed to the wobbling motion of dye on the silica surface and to the ionically bound probe, respectively). The dye was strongly adsorbed to unmodified silica nanoparticles, to the extent that less than 1% of the dye was present in the surrounding aqueous solution. Significant decreases in the degree of probe adsorption were obtained upon covalent modification of the silica with neutral or cationic silanes, with up to 80% of the probe being present in the aqueous solution in cases where the surface was coated with (3-aminopropyl)triethoxysilane. The addition of such agents also altered the fractional distribution between the nanosecond decay component and the residual anisotropy component in favor of the nanosecond component, indicative of weaker interactions between the dye and the modified surface (i.e., more wobbling motion). The data clearly show the power of time-resolved fluorescence anisotropy decay measurements for probing the modification of silica surfaces and should prove useful in characterization of new chromatographic stationary phases.

Adsorption↗
PubMed2004

Kinetics of C2(a3Piu) radical reactions with alkanes by LIF.

The reactions of C2(a3Piu) radicals with a series of alkanes have been studied at room temperature and 6.5 torr total pressure using the pulsed laser photolysis/laser-induced fluorescence technique. C2(a3Piu) radicals were generated by photolysis of C2Cl4 with the focused output from the fourth harmonic of a Nd: YAG laser at 266 nm. The relative concentration of C2(a3Piu) radicals was monitored on the (0,0) band of the C2(d3Pig <-- a3Piu) transition at 516.5 nm by laser-induced fluorescence. From the analysis of the relative concentration-time behavior of C2(a3Piu) under pseudofirst-order conditions, the rate constants for the reactions of C2(a3Piu) with alkanes (C1-C8) were determined. The rate constant increases linearly with the increasing of the number of CH2 groups in the alkanes. The experimental results indicate that the reaction of C2(a3Piu) with small alkanes (C1-C8) follows the typical hydrogen abstraction process. Based on the correlation of the experimental results with the bond dissociation energy of the alkanes, the reactions of C2(a3Piu) with small alkanes likely proceed via the mechanism of hydrogen abstraction.

Journal Article↗
PubMed2004

Observational evidence of a change in radiative forcing due to the indirect aerosol effect.

Anthropogenic aerosols enhance cloud reflectivity by increasing the number concentration of cloud droplets, leading to a cooling effect on climate known as the indirect aerosol effect. Observational support for this effect is based mainly on evidence that aerosol number concentrations are connected with droplet concentrations, but it has been difficult to determine the impact of these indirect effects on radiative forcing. Here we provide observational evidence for a substantial alteration of radiative fluxes due to the indirect aerosol effect. We examine the effect of aerosols on cloud optical properties using measurements of aerosol and cloud properties at two North American sites that span polluted and clean conditions-a continental site in Oklahoma with high aerosol concentrations, and an Arctic site in Alaska with low aerosol concentrations. We determine the cloud optical depth required to fit the observed shortwave downward surface radiation. We then use a cloud parcel model to simulate the cloud optical depth from observed aerosol properties due to the indirect aerosol effect. From the good agreement between the simulated indirect aerosol effect and observed surface radiation, we conclude that the indirect aerosol effect has a significant influence on radiative fluxes.

Journal Article↗
PubMed2004

Synthesis and release of steroids in intestines from cynomolgus monkeys (Macaca fascicularis).

To examine the synthesis and release of steroids in intestinal tissues from cynomolgus monkeys (Macaca fascicularis), we performed the following experiments: 1) incubated prepared intestinal tissues with [(3)H]testosterone to study the conversion to other steroids; 2) used a radioimmunoassay to determine steroid levels in six segments of intestinal tissues and contents (duodenum, jejunum, ileum, cecum, colon, and rectum); 3) localized testosterone in the six intestinal segments by immunofluorescence histochemistry; and 4) determined steroid levels in feces from males and females of various ages by radioimmunoassay to examine a correlation between steroid levels and age or sex. In prepared intestinal tissues, testosterone was converted into androstenedione, 5 alpha-dihydrotestosterone, and an unidentified substance; all of these steroids were detected in all segments of the intestinal tissues and contents by radioimmunoassay. Immunofluorescence showed that testosterone was located in all segments of intestinal epithelia. Androstenedione, testosterone, 5 alpha-dihydrotestosterone, and the unidentified substance were also detected in feces, and their levels were not affected by the age or sex of the animal. The present findings in cynomolgus monkeys led us to conclude that 1) steroids were synthesized in the intestines; 2) intestinal steroids were released from the six intestinal tissues to the intestinal cavities and excreted outside the body with feces; and 3) intestinal steroids were released irrespective of age or sex of the animal. Intestinal steroids seem to be paracrine or exocrine agents and to have different characteristics from classical serum steroids.

Age Factors↗
PubMed2004

[The changes of water channel protein 1 in the lungs of the drown rat].

OBJECTIVE: To observe water channel 1 protein in the lungs of the drown rat. METHODS: Immunohistochemical method and Colloidal gold of the electron microscopy were used to observe the location of aquaporin1(AQP1) on the rat lung tissue between the experiment group and control group. RESULTS: The positive expression of AQP1 was seen in the capillary endotheliocyte of the interstitium and around bronchi and in the alveolar endothelial cells. The difference in the value of integrated optical density between the two groups was statistically significant. AQP1 was located in the type I alveolar cells, and the difference in the semi-quantity of Colloidal gold of the electron microscopy between the two groups was statistically significant as well. CONCLUSION: The above data suggest that AQP1 positive reaction is one of the sensitive signs of drowning and it is located in the type I alveolar cells.

Animals↗
PubMed2004

[Changes of connexin 43 in rabbit with early myocardial ischemia].

OBJECTIVE: To reveal gap junction connexin 43 (Cx43) in rabbit with early myocardial ischemia. METHODS: The left coronary arteries were ligated to create early myocardial ischemia. Cx43 was visualized by use of SP immunohistochemical method (IHC) and Colloidal gold of the electron microscopy, and a comparison was made between the experiment group and the control group. The semi-quantitation assessment was performed. RESULTS: The positive areas of Cx43 gap junctions by IHC and Colloidal gold particles of the electron microscopy were found decreased by about 40% at 30 minutes of acute myocardial ischemia. The distributions were not obviously modified. CONCLUSION: The decrease of Cx43 is characterized by the time during myocardial ischemia, and the early stage of acute myocardial ischemia in rat is of positive significance.

Animals↗
PubMed2004

[A preliminary study on salt contents of soil in root-canopy area of halophytes].

The results showed that among the 27 sampling sites, the salt content in rhizosphere of herbaceous halophytes increased at 7 sites and decreased at 20 sites. The variation of soil salt content in the RUE micro-area of shrubby halophytes was related to the growth status of the plants. The salt content in rhizosphere decreased a little at the early stage of plant development, but that in RUE micro-area tended to increase and accumulated most quickly at the site of the canopy edge soil. An obvious variation of salt components was found in the RUE micro-area of different types of halophytes. The Na+/K+ ratio tended to decrease in succulent halophytes and salt secrete halophytes. Among 53 sampling sites, only 14 sampling sites had a higher ratio of Na+/K+ in rhizosphere soil than in background soil, and only 10 sampling sites had a higher ratio of Na+/K+ in canopy-under soil than in background soil. However, the Na+/K+ ratio in the canopy edge soil of Tamarix and Nitraria tended to increase when they grew weakly. By contraries, the Na+/K+ ratio in the rhizosphere was higher than that in background soil at 3 of 4 sampling sites of Phragmites australia, which indicated that the Na+/K+ ratio in the rhizosphere of exclude halophytes tended to increase. The variation of SO4(2-)/Cl- ratio in the RUE micro-area was different in the 3 types of halophytes. For salt secrete halophytes, it decreased obviously in rhizosphere soil, canopy-under soil and canopy-edge soil; for succulent herbaceous halophytes, it tended to increase in rhizosphere soil; and for succulent shrubby halophytes, it tended to decrease in rhizosphere and in canopy-under soil, and tended to increase in canopy-edge soil. The SO4(2-)/Cl- ratio had no big change for exclude-halophytes. The reduction of the salts in rhizosphere of herbaceous halophytes was mainly because of their plant uptake, and the accumulation of salts in the RUE micro-area of shrubby halophytes was because the salt absorbed from the around soil returned to the RUE micro-area again. Because of the selective uptake by plant, the salt component varied with different types of halophytes. Most halophytes except Phragmites australia take more Na+, and hence the Na+/K+ ratio in the rhizosphere tends to decrease. The SO4(2-)/Cl- ratio in the RUE micro-area of salt secrete halophytes trended reduce, mainly because this type of halophyte can secrete more Cl- with its growth.

Chlorides↗