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Biomedical subjects

Jing Yang

Publications and source records attributed to Jing Yang.

229 records · Page 13Linked to original sources
PubMed2002

[The circulatory and respiratory dynamic mechanisms of lung Qi-deficiency].

As the transportation of O2 and CO2 inside human body is an integrated aspect of Qi-blood transportation, a hemodynamic model is established based on the analysis of the respiratory and circulation system. The results of such model show that the abnormality of the circulatory and respiratory parameters always lead to a reduction of Po2 (O2 pressure) in tissue fluid, and then a Lung Qi-Deficiency Syndrome (QDS). This model can be used to quantitatively explain, to some extent, the physiological phenomena of Lung QDS, and could combine all the discoveries of in clinical researches, on Lung QDS. The measurement of Po2 in tissue fluid as an index to analyze Lung QDS is in accordance with TCM and TMM (the theory of modern medicine). This model may provide a new approach in clinical research of Lung QDS.

Hemodynamics↗
PubMed2000

Cloning and Preliminary Characterization of Regulatory Domain of Mouse Nestin Gene.

Mouse nestin genomic DNA(23.3 kb)was obtained after genomic library screening. Sequence comparison of the cDNA and genomic DNA revealed three introns in this gene. The positions and length of these introns are conserved among rat and human. The effect of the second intron of mouse nestin gene on the expression of luciferase reporter gene was investigated in vitro. Transient transfection of the second intron and its series deletions of mouse nestin gene showed that the second intron of mouse nestin gene could enhance reporter gene expression and the activity was contributed by a fragment about 800 bp long of its 3' end.

Journal Article↗
PubMed1999

The Regulation of Xmyf-5 Gene, a Muscle Determinant, Expression in Xenopus Laevis.

Xmyf-5 gene is a member of the myogenic regulatory genes important for Xenopus muscle cell commitment and differentiation. To analyze the mechanism involved in regulating Xmyf-5 gene activity in the process of myogenesis, the 4.9 kb 5' upstream sequence of Xmyf-5 was identified. LacZ gene could be activated in the presomitic mesoderm in stage 14 embryos and myotomes in stage 25 embryos when it was driven by the 4.9 kb sequence and introduced into embryos at 2 cell stage. The Luciferase reporter gene activities driven by deletion constructs suggested that there are at least one enhancer between 4.9 kb and 3.5 kb of Xmyf-5 5' upstream DNA and one negatively regulative factor between 2.0 kb and 0.9 kb of the Xmyf-5 5' upstream DNA. In addition, sequence analysis indicated that a 100 bp fragment 5' upstream of Xmyf-5 contained conserved regulative elements such as OLS which were found in other vertebrates.

Journal Article↗
PubMed1999

N-cadherin Invovles in P19 Cell in vitro Neuronal Differentiation.

N-cadherin plays an important role in the early morphogenesis of neural tissue. For exploring the possible role of N-cadherin in neuronal differentiation in vitro, we chose RA induced P19 cell neuronal differentiation as a model system. Using RT-PCR, we examined the expression pattern of N-cadherin during P19 cell neuronal differentiation. The results showed that N-cadherin expression was increased rapidly during RA induction with its highest expression level at day 3 of neuronal differentiation, then down-regulated along with neuronal maturation. This expression pattern was similar with CNS development in vivo. Then, we constructed a N-cadherin expression-vector and transfected in P19 cells. The stable transfected cell lines, N-cadherin/P19 were selected, and we found that, after aggregated 4 days, the N-cadherin overexpression P19 cells could differentiate into neuron-like cells without the RA induction. The immunocytochemical staining showed that these neuron-like cells expressed neuron specific marker, NF160. These results suggest that N-cadherin gene is involved in P19 neuron differentiation.

Journal Article↗
PubMed1999

In Situ Hybridization of RA Induced P19 Cells.

P19 EC cells can be induced to differentiate into neurons in vitro when they were treated with 1x10(-6) mol/L retinoic acid. In the process of neuronal differentiation, P19 cells gradually migrate and form aggregates. Aggregated cells weakly adhered to the surface of cell culture dishes are usually dropped of during the procedure of in situ hybridization. To keep cells on the coverslips, we modified the procedure by using 1 g/L gelatin solution to cover the cells and substituting proteinase K treatment with pepsin treatment which digested cellular proteins mildly. With the treatment of pepsin, RNA probe can easily go through cell membrane and bind to its target, without loss of cell from coverslips.

Journal Article↗
PubMedDate not supplied

Synthesis and characterization of poly(butylene succinate-co-butylene malate): a new biodegradable copolyester bearing hydroxyl pendant groups.

A new biodegradable copolyester, poly(butylene succinate-co-butylene malate) P(BS-co-BM), has been preliminarily prepared with optically active centers and lateral hydroxyl functional groups via a four-step synthetic strategy. First, an optically active benzyl-protected dimethyl malate was synthesized from a starting material of (S)-dimethyl malate and purified with good yield. Then, copolyester poly(butylene succinate-co-benzyl-protected butylene malate), P(BS-co-BBM), was prepared through a skilled condensation copolymerization of the benzyl-protected dimethyl malate, dimethyl succinate, and 1,4-butanediol in the presence of titanium tetraisopropoxide as the catalyst. Finally, a Pd/C catalyzed hydrogenation was applied to eliminate the benzyl protection group in a mixed solution of THF and methanol; thus the target copolyester P(BS-co-BM) was attained. On the other hand, physical properties of the synthesized copolyesters were systematically characterized by means of nuclear magnetic resonance spectrometer, Fourier transformed infrared spectrometer, gel permeation chromatography, optical polarimeter, quantitative hydroxyl titration, and thermal analytical instruments. The experimental evidence demonstrated a successful construction of the product P(BS-co-BM) bearing lateral hydroxyl functional groups. It was also revealed that the lower BBM unit content was in the benzyl-protected optically active P(BS-co-BBM) copolyester, the higher melting point T(m), crystallinity, the broader molecular distribution, and the lower glass transition temperature T(g) would be detected, and these results can be accounted for the presence of bulky lateral benzyl moieties. In contrast, the deprotected product P(BS-co-55 mol % BM) showed a higher T(m), crystallinity and lower T(g) than its counterpart P(BS-co-55 mol % BBM). Interestingly, a thermal stability as high as that of the linear PBS was observed for P(BS-co-55 mol % BM) while a strong BBM unit content dependence of thermal stability was detected for the benzyl-protected copolyester P(BS-co-BBM)s. Therefore, these results may be beneficial for the new optically active P(BS-co-BM) bearing hydrophilic hydroxyl functional groups as a potential biomaterial.

Biodegradation, Environmental↗
PubMedDate not supplied

Syntheses and physical characterization of new aliphatic triblock poly(L-lactide-b-butylene succinate-b-L-lactide)s bearing soft and hard biodegradable building blocks.

This study presents chemical syntheses and physical characterization of a new aliphatic poly(L-lactide-b-butylene succinate-b-L-lactide) triblock copolyester with soft and hard biodegradable building blocks. First, poly(butylene succinate) (PBS) prepolymers terminated with hydroxyl functional groups were synthesized through melt polycondensation from succinic acid and 1,4-butanediol. Further, a series of new PLLA-b-PBS-b-PLLA triblock copolyesters bearing various average PLLA block lengths were prepared via ring opening polymerization of L-lactide with the synthesized hydroxyl capped PBS prepolymer (Mn = 4.9 KDa) and stannous octanoate as the macroinitiator and catalyst, respectively. By means of GPC, NMR, FTIR, DSC, TGA, and wide-angle X-ray diffractometer (WAXD), the macromolecular structures and physical properties were intensively studied for these synthesized PBS prepolymer and PLLA-b-PBS-b-PLLA triblock copolyesters. 13C NMR and GPC experimental results confirmed the formation of sequential block structures without any detectable transesterification under the present experimental conditions, and the molecular weights of triblock copolyesters could be readily regulated by adjusting the feeding molar ratio of L-lactide monomer to the PBS macroinitiator. DSC measurements showed all single glass transitions, and their glass transition temperatures were found to be between those of PLLA and PBS, depending on the lengths of PLLA blocks. It was noteworthy that the segmental flexibilities of the hard PLLA blocks were found to be remarkably enhanced by the more flexible PBS block partner, and the PBS and PLLA building blocks were well mixed in the amorphous regions. Results of TGA analyses indicated that thermal degradation and stabilities of the PLLA blocks strongly depended on the average PLLA block lengths of triblock copolyesters. In addition, FTIR and WAXD results showed the coexistence of the assembled PLLA and PBS crystal structures when the average PLLA block length became larger than 7.8. These results may be beneficial for this new biodegradable aliphatic triblock copolyester to be applied as a potential biomaterial.

Biocompatible Materials↗
PubMedDate not supplied

Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s with functional carbonate building blocks. 1. Chemical synthesis and their structural and physical characterization.

This study presents chemical synthesis, structural, and physical characterization of novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s P(BS-co-CC) bearing functional carbonate building blocks. First, five kinds of six-membered cyclic carbonate monomers, namely, trimethylene carbonate (TMC), 1-methyl-1,3-trimethylene carbonate (MTMC), 2,2-dimethyl-1,3-trimethylene carbonate (DMTMC), 5-benzyloxytrimethylene carbonate (BTMC), and 5-ethyl-5-benzyloxymethyl trimethylene carbonate (EBTMC), were well prepared from ethyl chloroformate and corresponding diols at 0 degrees C in THF solution with our modified synthetic strategies. Then, a series of new P(BS-co-CC)s were synthesized at 210 degrees C through a simple combination of poly-condensation and ring-opening-polymerization (ROP) of hydroxyl capped PBS macromers and the prepared carbonate monomers, and titanium tetra-isopropoxide Ti(i-OPr)4 was used as a more suitable catalyst of 5 candidate catalysts which could concurrently catalyze poly-condensation and ROP. By means of NMR, GPC, FTIR, and thermal analytical instruments, macromolecular structures and physical properties have been characterized for these aliphatic poly(ester carbonate)s. The experimental results indicated that novel biodegradable P(BS-co-CC)s were successfully synthesized with number average molecular weight Mn ranging from 24.3 to 99.6 KDa and various CC molar contents without any detectable decarboxylation and that the more bulky side group was attached to a cyclic carbonate monomer, the lower reactivity for its copolymerization would be observed. The occurrences of 13C NMR signal splitting of succinyl carbonyl attributed to the BS building blocks could be proposed due to the randomized sequences of BS and CC building blocks. FTIR characterization indicated two distinct absorption bands at 1716 and 1733 approximately 1735 cm(-1), respectively, stemming from carbonyl stretching modes for corresponding BS and CC units. With regard to their thermal properties, it is seen that the synthesized P(BS-co-CC)s exhibited thermal degradation temperatures 10 approximately 20 degrees C higher than that of PBS. On the basis of the synthesized P(BS-co-BTMC)s, new aliphatic poly(butylene succinate-co-5-hydroxy trimethylene carbonate)s were further synthesized, bearing hydrophilic hydroxyl pendant functional groups through an optimized Pd/C catalyzed hydrogenation. These semi-crystalline new biodegradable aliphatic copolymers with tunable physical properties and functional carbonate building blocks might be expected as potential new biomaterials.

Biocompatible Materials↗
PubMedDate not supplied

Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s bearing functionalizable carbonate building blocks: II. Enzymatic biodegradation and in vitro biocompatibility assay.

In a previous study, we have reported chemical synthesis of novel aliphatic poly(butylene succinate-co-cyclic carbonate) P(BS-co-CC)s bearing various functionalizable carbonate building blocks, and this work will continue to present our new studies on their enzymatic degradation and in vitro cell biocompatibility assay. First, enzymatic degradation of the novel P(BS-co-CC) film samples was investigated with two enzymes of lipase B Candida Antartic (Novozyme 435) and lipase Porcine Pancreas PPL, and it was revealed that copolymerizing linear poly(butylene succinate) PBS with a functionalizable carbonate building block could remarkably accelerate the enzymatic degradation of a synthesized product P(BS-co-CC), and its biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the cyclic carbonate (CC) comonomer structure and molar content, molar mass, thermal characteristics, morphology, the enzyme-substrate specificity, and so forth. Further, the biodegraded residual film samples and water-soluble enzymatic degradation products were allowed to be analyzed by means of proton nuclear magnetic resonance (1H NMR), gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), attenuated total reflection FTIR (ATR-FTIR), scanning electron microscope (SEM), and liquid chromatograph-mass spectrometry (LC-MS). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the noncrystalline domains was suggested for the synthesized new P(BS-co-CC) film samples. With regard to their cell biocompatibilities, an assay with NIH 3T3 mouse fibroblast cell was conducted using the novel synthesized P(BS-co-CC) films as substrates with respect to the cell adhesion and proliferation, and these new biodegradable P(BS-co-CC) samples were found to exhibit as low cell toxicity as the PLLA control, particularly the two samples of poly(butylene succinate-co-18.7 mol % dimethyl trimethylene carbonate) P(BS-co-18.7 mol % DMTMC) and poly(butylene succinate-co-21.9 mol % 5-benzyloxy trimethylene carbonate) P(BS-co-21.9 mol % BTMC) were interestingly found to show much better cell biocompatibilities than the PLLA reference.

Animals↗
PubMedDate not supplied

Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols.

This study presents syntheses, structural characterization, and crystallization kinetic investigation of new structurally well-defined star-shaped poly(l-lactide)s (PLLAs). First, a series of new 3- to 6-arm star-shaped PLLAs were synthesized through SnOct(2) catalyzed ring-opening polymerization of (l)-lactide with natural sugar alcohols of glycerol, erythritol, xylitol, and sorbitol as the favorable initiators. Subsequently, their chemical structures were characterized by means of GPC, NMR, and viscometer with respect to the star-shaped structures, demonstrating the well-defined arm structures as evidenced on the g(1/2)/g' values, where g and g' denote the ratios of mean-square radius of gyration and intrinsic viscosity of a star-shaped polymer to those of a linear structural reference with similar absolute molecular weight. Furthermore, spherulite morphologies and growth rates were studied by a polarized microscopy (POM) for the synthesized star-shaped PLLAs with different molecular weights, and it was found that the more arms of a star-shaped PLLA finally resulted in a lower spherulite growth rate. With regard to the crystallization kinetics of these star-shaped PLLAs, isothermal and nonisothermal crystallization were examined by differential scanning calorimeter (DSC). It was found that Avrami exponent n values of isothermal crystallization were almost independent of the isothermal crystallization temperature T(c) for different series of star-shaped PLLAs. In contrast, the values of Avrami exponent n were observed to strongly depend on the star-shaped structures with different arms, implying their distinct nucleation mechanisms, and the more arms of a star-shaped PLLA led to a slower isothermal crystallization rate. On the basis of a modified Avrami equation, new light was shed on the nonisothermal crystallization kinetics for the star-shaped PLLAs, and the activation energies were found to vary from 146.86 kJ/mol for the linear PLLA EG-3 to 221.23 kJ/mol of the star-shaped S-3, demonstrating much decreased crystallizabilities of star-shaped PLLAs with more arms.

Biodegradation, Environmental↗
PubMedDate not supplied

The effects of different hands' responses on main ERP components.

The authors recorded event-related potentials (ERPs) in 14 subjects to explore the effects of different hands'responses on ERP components. Subjects used two different fingers of one hand to indicate whether the two sequentially presented visual stimuli were of the same color (match) or not (conflict) in the first half of the test, while they used the other hand in the last half. ERP components of contingent negative variation (CNV), P100, N160, N200, and late positive component (LPC) were recorded in either the match or conflict condition. Component N270 was recorded only in the conflict condition mainly on the centrofrontal area (F3, F4). The mean amplitude of the CNV was significantly higher when subjects used the right hand to respond. The mean amplitudes of N160 in the two conditions and N200 in the conflict condition were significantly higher when the left hand was used to indicate a response. There was no significant difference in the amplitude of N270 between the left-hand and right-hand responses. The N270 is thought to reflect activity in a conflict processing system. The LPC component was not affected by different hands'response-effect.

Adult↗
PubMedDate not supplied

Measuring data abstraction quality in multiresolution visualizations.

Data abstraction techniques are widely used in multiresolution visualization systems to reduce visual clutter and facilitate analysis from overview to detail. However, analysts are usually unaware of how well the abstracted data represent the original dataset, which can impact the reliability of results gleaned from the abstractions. In this paper, we define two data abstraction quality measures for computing the degree to which the abstraction conveys the original dataset: the Histogram Difference Measure and the Nearest Neighbor Measure. They have been integrated within XmdvTool, a public-domain multiresolution visualization system for multivariate data analysis that supports sampling as well as clustering to simplify data. Several interactive operations are provided, including adjusting the data abstraction level, changing selected regions, and setting the acceptable data abstraction quality level. Conducting these operations, analysts can select an optimal data abstraction level. Also, analysts can compare different abstraction methods using the measures to see how well relative data density and outliers are maintained, and then select an abstraction method that meets the requirement of their analytic tasks.

Journal Article↗