Electrospray ionization mass spectral fragmentation mechanisms of DNA-recognizing polyamides containing N-methylpyrrole and N-methylimidazol.
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DNA↗
Biomedical subjects
Jiang Zhou
Publications and source records attributed to Jiang Zhou.
Electrospray ionization mass spectrometric analysis of noncovalent complexes between DNA and polyamides containing N-methylpyrrole and N-methylimidazole.
Electrospray ionization mass spectrometry was utilized to investigate the noncovalent complexes between novel polyamides and DNA containing the TCCT sequence. We analyzed the noncovalent binding of the polyamides with the DNA and assessed their relative affinities and stoichiometry. The results confirm that hairpin polyamides have higher binding affinities than three-ring polyamides. The hairpin polyamide (PyPyPyPygammaPyImImPybetaDp) has the highest affinity, and the beta-linked polyamide (PyPyPybetaImImImbetaDp) shows a dominant 1:2 binding stoichiometry. Two groups of competition experiments were undertaken to compare the binding affinities of the duplex DNA with different polyamides directly. The affinity scale thus obtained for the group-1 polyamides is PyPyPyPygammaPyImImPybetaDp > PyPyPybetaImImImbetaDp approximately PyPyPygammaImImImbetaDp >> PyPyPybetaDp > PyImImbetaDp approximately ImImPybetaDp, and the order for the group-2 polyamides is PyPyPygammaImImImbetaDp > PyPyPygammaImImImbetaOEt > PyPyPygammaImImImbetaCOOH.
DNA↗
Electrospray ionization mass spectral characteristics and fragmentation mechanisms of novel photoinduced DNA-cleaving agents formed as conjugates of haloarenes and polyamides containing N-methylimidazole.
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DNA↗
[Alterations in expression of F-actin and DNA of fluid shear stress treated-mesenchymal stem cells affected by titanium particles loading].
Particulate wear debris within the bone-prosthesis microenvironment generated by normal wear and corrosion of orthopaedic implants is considered to be one of the main factors responsible for chronic aseptic inflammation and development of osteolysis in the long-term instability and failure of total joint arthroplasty. While the decrease in bone volume caused by wear debris-induced osteolysis could have been compensated by enough new bone matrix secreted by osteoblasts. Actually, the normal osteoblastic population depend on the regular differentiation and proliferation of their progenitor cells--bone marrow mesenchymal stem cells (MSCs). This study aims to investigate the potential mechanism for the rat MSCs cytotoxicity upon exposure to Titanium (Ti) particles. Rat mesenchymal stem cells (rMSCs) isolated from 3-month-old male Sprague-Dawley rats by Percoll intensity gradient method were cultured in DMEM medium (low glucose) supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 micrograms/ml streptomycin in a humidified incubator with 5% CO2 at 37 degrees C. In order to gain the homogenous cell population, rMSCs were passaged to 3-4th subpassage which were used in all the experiment groups. Then rMSCs were seeded in the 6 well culture plates and exposed to three different circle diameters (mean size, TD1: 0.9 micron, TD2: 2.7 microns, TD3: 6.9 microns) with three different concentrations (0.1 wt%, 0.05 wt%, 0.01 wt%, W/V) at different durations (8 h, 16 h, 24 h,), respectively. Unexposed rMSCs were used as control. In the given periods of Ti loading, fluid shear stress (FSS) was applied to each group cells. The expression of F-actin and DNA of the rMSCs at the indicated time were determined with laser confocal scanning microscopy and image analysis software. The results showed that there was up-regulation expression of F-actin in the rMSCs without Ti particles loading but in the presence of FSS. Ti particles loading can suppress the expression of F-action and DNA of rMSCs, but this down-regulation response varied with the three circle diameter, concentrations and durations of Ti particles. Among three kinds of diametrically different Ti particles, submicron Ti particles (0.9 micron) had the greatest suppressive response on rMSCs, together with some apoptosis bodies. Under the same diameter condition, the inhibition induced by Ti particles loading was in a manner dependent on the particles concentration and exposure duration. The reductive effects produced from 0.1 wt% Ti was the greatest and earliest among the responses from Ti particles at three different concentrations; and the lower the concentration, the weaker the repressive influence. Furthermore, with the elongation of exposure to Ti particles, the expression of F-actin and DNA decreased gradually, the lowest level was at 32 h. These findings demonstrated that Ti particles loading can attenuate rMSCs' viability in a manner dependent on the circle diameter, particles concentration, treatment period, suggesting that a reduction in the number of viable MSCs together with a compromise of the their differentiation into functional osteoblast may exacerbate aseptic loosening of total joint implant. Further investigation into particles-mediated suppression of MCSs viability may reveal novel mechanism of implant loosening and aid in development and application of osteolytic drug therapy and the optimization of design and selection of future orthopaedic biomaterials, thereby improving long-term compatibility and stability for arthroplasty patients.
Actins↗
[Time-dependent increase of interleukin-8 production in endothelial cells exposed to fluid shear stress].
Fluid shear stress plays an important role in many physiological and pathological processes of the cardiovascular system. Being constantly exposed to mechanical shear stress, vascular endothelial cells can sense the changes of blood flow forces and regulate vascular structure and function. Previous studies demonstrated that IL-8 mRNA expression in endothelial cells was modulated by fluid shear stress. To identify the effect of fluid shear stress on IL-8 protein production of human umbilical vein endothelial cells (HUVECs), we employed quantitative sandwich enzyme-linked immunosorbent assay (ELISA) to measure the IL-8 protein. It was found that the HUVECs not treated with fluid shear stress secreted very little IL-8 in culture media. However, after 1 hour of exposure to shear stress, the secretion of IL-8 increased; at 5 hours of exposure, the seceretion reached the summit; at 8 hours of exposure, the secretion of IL-8 decreased and then remained at a constant level till the end (12 hours) of the experiment. The increase of IL-8 secretion induced by shear stress was time-dependent. The biphasic response of IL-8 protein production was found in experiments in which the shear stress applied was 2.09 dyne/cm2, 4.61 dyne/cm2, and 6.19 dyne/cm2. The IL-8 protein production in response to shear stress was very similar to the IL-8 gene expression in response to shear stress, and had the obvious delay. The induction of IL-8 protein production by fluid shear stress is probably due to the gene expression. This in vitro study demonstrates that the production of IL-8 can be regulated by fluid shear stress. Fluid shear stress induces a biphasic response of human HUVECs' production of IL-8 protein. These observations suggest that the process of the fluid shear stress induced HUVECs' production of IL-8 may play an important role in the genesis and development of both inflammation and atherosclerosis.
Cells, Cultured↗
[Construct tissue-engineered bone by co-seeding marrow stromal cells and endothelial cells].
To identify the role of co-seeding marrow stromal cells (MSCs) and endothelial cells (ECs) onto biocomposite in constructing tissue-engineered bone for promoting osteogenesis and angiogenesis, we seeded rat marrow stromal cells (rMSCs) and human umbilical vein endothelial cells (hUVECs) onto poly (L-lactic acid)/beta-tricalcium phosphate (PLLA/beta-TCP) macroporous composite (the test group), and seeded rMSCs onto the same kind of composite (the control group). We implanted these biocomposites into the thighs of nude mice intramuscularly and sacrificed these mice at 1, 4, 8, 12, 16 weeks after implantation, respectively. Biocomposites were taken out and histomorphometry was performed. Image manipulation technology was used to calculate the percentages of new bone area and material area in the test group and control group. We found that the percentage of new bone area of test group increased faster than that of control group, the percentage of material of test group decreased faster than that of control group, and the growth of capillary network of test group was much better than that of control group. These results suggest that co-seeding MSCs and ECs onto scaffold for constructing tissue-engineered bone is beneficial to osteogenesis, to angiogenesis in the prosthesis, and to the degradation of scaffold, and it is of significance in the research of bone tissue engineering.
Absorbable Implants↗
[Establishment of keratinocyte-specific Cre recombinase transgenic mice].
A keratinocyte-specific Cre transgenic construct (pK5-Cre) containing the keratin 5 promoter, Cre recombinase gene and polyA of human growth hormone gene was generated. The 4.2 kb DNA fragment of K5-Cre-hGH was introduced into 720 fertilized zygotes by microinjection. 695 injected eggs were implanted into the oviduct of 29 female mice respectively, from which 48 off-spring were obtained. Twelve mice carrying the transgene were identified by genotyping, and the integration efficiency is 25%. The K5-Cre transgenic mice were crossed with Smad4 conditional gene targeting mice to check the tissue-specific expression of the Cre recombinase and the Cre mediated recombination in multiple tissues. The results showed that the Cre recombinase was expressed in skin tissue only and successfully mediated the recombination between the loxP sites in vivo.
Animals↗
[Research in use of vascular endothelial cells to promote osteogenesis of marrow stromal cells].
Osteogenesis deep in the materials is postponed because the blood vessels grow into the materials very slowly. It is one of the key challenges to the bone tissue engineering researchers. However, it was found that marrow stromal cells can produce vascular endothelial growth factor (VEGF) while endothelial cells produce bone morphogenetic protein (BMP). So we presume if we have co-culture of marrow stromal cells and endothelial cells on the biomaterials, osteogenesis and angiogenesis may be promoted simultaneously. In this experiment, we compare the alkaline phosphatase (ALP) activity and osteocalcin (OCN) production of three groups: the marrow stromal cells under activation of endothelial cells culture fluid, the induced marrow stromal cells, and the untreated marrow stromal cells. The results reveal that the ALP activity and OCN production of the marrow stromal cells under activation of endothelial cell culture fluid and the ALP activity and OCN production of the induced marrow stromal cells do not show statistically significant difference, but they are significantly higher than those of the untreated marrow stromal cells (P < 0.01). It is concluded that the VEGF in the endothelial cell culture fluid can promote osteogenesis as effective as osteogenic induction medium can do.
Alkaline Phosphatase↗
Competing effects of buckling and anchorage strength on optimal wheat stalk geometry.
We seek the ideal wheat stalk, which minimizes the structural mass required to support a fixed grain load in the presence of gravity and wind. The optimization search is restricted to stepped cylindrical stems of known moduli and density but unknown dimension. Stem buckling and root anchorage strength are assumed to place restrictions on the permissible stalk resonant frequency in the presence of a specified wind forcing frequency. These effects are described mathematically, and the penalty parameter method is used to find stem mass minima for various stalk heights. In general, there are two alternative solution branches. The lower solution is the global minimum but it is probably impractical for field crops exposed to natural wind. The upper minimum is more conservative and therefore requires more stem mass. Due to the competing requirements of buckling versus anchorage strength, the parameter study shows that optimal wheat stem geometry has a nonlinear dependence on the intensity of gravity and the frequency spectra of the wind.
Computer Simulation↗
[Generation and characterization of chondrocyte specific Cre transgenic mice].
A chondrocyte specific transgenic construct (pcol2A1-Cre) containing the cartilage specific type II collagen A1 promoter, the Cre recombinase gene and the polyA of human growth factor gene was generated. The 9.3 kb DNA fragments were recovered from Not I digested fragments and microinjected into 323 fertilized eggs. The injected eggs were implanted into the oviduct of 14 female mice. In the 52 offsprings, there were 10 mice carring the transgene identified by PCR, and the efficiency was 19.2%. The col2A1-Cre transgenic mice were crossed with a conditional gene targeting mice to check the Cre mediated recombination in multiple tissues. The results of the PCR analysis suggested that the Cre recombinase was expressed only in cartilaginous tissue and could mediate the recombination between the LoxP sites in vivo. The result was further confirmed by Southern-blot.
Animals↗
A transgenic mouse that targets the expression of Cre recombinase in pancreatic tissue.
The transgenic mice that express Cre recombinase in a tissue specific manner is a powerful tool in generating the conditional gene knockout mice. The rat insulin promoter was cloned target the expression of Cre in pancreatic tissue. The Cre gene was modified by adding the nuclear localization signal and the sequence for initiation by eukaryotic ribosomes at 5' terminal of the Cre gene. Cre gene was linked to the intron of human growth factor gene. This construct was introduced into the mouse eggs using microinjection. Seven mice were identified as founders carrying the Cre gene by PCR. The results of RT-PCR showed that the transgenic mouse from one founder could transcribe the foreign gene in pancreas. The Southern blot analysis indicated that the Cre recombinase expressed in pancreas of the transgenic mouse was functional.
Animals↗
[Echolocation sound waves, morphological features and foraging strategies in Hipposideros pratti].
Studies on the echolocation sound waves in different states (flying and hanging), morphological features and ecological processes (foraging strategies, foraging habitat and diet type) of Hipposideros pratti showed that H. pratti had CF (constant frequency)-FM (frequency modulated) echolocation sounds. There were some differences in dominant frequency (caused by Doppler compensating effect), pulse repetition rate, pulse duration and interpulse interval between the bats at flying and hanging. The dominant frequency, FM bandwidth, pulse duration and interpulse interval were lower, while the pulse repetition rate and duty cycle were higher at flying than at hanging. All the differences indicated that H. pratti could adopt specific echolocation sounds to adapt to specific environments and conditions to detect, approach and capture their preys successfully. On the basis of echolocation sound and field observation, it was concluded that H. pratti might search the preys at flying in the period of insect fastigium, and after the period, it might search the targets at hanging. The foraging habitat was near the tree crowns, and the preys consisted mainly of relatively large insects, such as beetles.
Animals↗