Biomedical subjects
Publications and source records attributed to D Liang.
The description characters of Herba Sedum aizoon were recounted. And the histological characters of the root, rhizome, stem, leaf and flower of the plant were reported. The characters of the isolated tissue and powder were also involved. These results provided valuable reference information for putting the medicinal resource to rational exploitage and use.
Smad7 is an inducible intracellular inhibitor of transforming growth factor-beta (TGF-beta) signaling that is regulated by diverse stimuli including members of the TGF-beta superfamily. To define the molecular mechanisms of negative control of TGF-beta signaling, we have isolated the human SMAD7 gene and characterized its promoter region. A -303 to +672 SMAD7 region contained a palindromic GTCTAGAC Smad binding element (SBE) between nucleotides -179 and -172 that was necessary for the induction of a Smad7 promoter luciferase reporter gene by TGF-beta. Electrophoretic mobility shift assays using oligonucleotide probes demonstrated that TGF-beta rapidly induced the binding of an endogenous SBE-binding complex (SBC) containing Smad2, Smad3, and Smad4. Transfection assays in mouse embryonic fibroblasts (MEFs), with targeted deletions of either Smad2 or Smad3, and the Smad4-deficient cell line MD-MBA-468 revealed that both Smad3 and Smad4, but not Smad2, were absolutely required for induction of the Smad7 promoter reporter gene by TGF-beta. Furthermore, the TGF-beta-inducible SBE-binding complex was diminished in Smad2-deficient MEFs when compared with wild type MEFs and not detectable in Smad3-deficient MEFs and MD-MBA-468 cells. Taken together, our data demonstrate that TGF-beta induces transcription of the human SMAD7 gene through activation of Smad3 and Smad4 transcription factor binding to its proximal promoter.
A number of pathogenic and proinflammatory stimuli, and the transforming growth factor-beta (TGF-beta) exert opposing activities in cellular and immune responses. Here we show that the RelA subunit of nuclear factor kappaB (NF-kappaB/RelA) is necessary for the inhibition of TGF-beta-induced phosphorylation, nuclear translocation, and DNA binding of SMAD signaling complexes by tumor necrosis factor-alpha (TNF-alpha). The antagonism is mediated through up-regulation of Smad7 synthesis and induction of stable associations between ligand-activated TGF-beta receptors and inhibitory Smad7. Down-regulation of endogenous Smad7 by expression of antisense mRNA releases TGF-beta/SMAD-induced transcriptional responses from suppression by cytokine-activated NF-kappaB/RelA. Following stimulation with bacterial lipopolysaccharide (LPS), or the proinflammatory cytokines TNF-alpha and interleukin-1beta (IL-1beta, NF-kappaB/RelA induces Smad7 synthesis through activation of Smad7 gene transcription. These results suggest a mechanism of suppression of TGF-beta/SMAD signaling by opposing stimuli mediated through the activation of inhibitory Smad7 by NF-kappaB/RelA.
A new method to introduce the concentration gradient into the capillary has been developed and its application to DNA capillary electrophoresis is presented. The concentration gradient produced by mixing 5% w/v polyacrylamide-co-poly(N-dimethylacrylamide) (PAM-co-PDMA) solution and 1 x Tris/N-tris(hydroxymethyl)methyl-3-amino-propanesulfonic acid/EDTA (TT) + 5 M urea buffer was successfully achieved by using two programmable syringe pumps with strict control of dead volume, flow rate, and pressure balance. This method has the advantages of high stability, reproducibility, and versatility. The column with concentration gradient greatly improved the resolution, especially for the large DNA fragments, due to a decrease in band width broadening with time. A column containing 2-4% w/v gradient in four steps had a longer read length, shorter separation time and better resolution (after 380 base) than that of 4% w/v single concentration polymer solution. The number of steps in the gradient had almost no effect on the performance. The change in the average concentration by relocating the position of the same step gradient, i.e., a combination of different low concentration to high concentration polymer solution ratios, resulted in a different migration time, read length and resolution.
Nestmate recognition plays a key role in the behavior and evolution of social insects. We demonstrated that hydrocarbons are the chemical cues used in Argentine ant, Linepithema humile, nestmate recognition, and that these hydrocarbons can be acquired from insect prey. Consequently, Argentine ant cuticular hydrocarbon patterns reveal the same hydrocarbons present in their diet. Diet alters both the recognition cues present on the cuticular surface and the response of nestmates to this new colony odor, resulting in aggression between former nestmates reared on different insect prey.
The effects of temperature, Mg2+, EDTA concentration and rinsing on extra- and intra-cellular DNase activity of Spirulina platensis strain SSP-14, were investigated. The results indicate that the tested strain contains very high extra- and intracellular DNase activity, which actually hinders the transfer of foreign gene(s) to S. platensis, a cyanobacterium with multiple economic potentials. The extracellular DNase activity could easily be removed by rinsing the cells with Zarrouk medium more than once. The intracellular DNase activity could also be inhibited by (1) removal of Mg2+, (2) maintaining EDTA concentration above 1 mmol l(-1), and (3) manipulating below 0-4 degrees C, during all the incubation procedures. We suggest that, by using one or more of, or combining, all those experimental conditions, the chances of foreign DNA attempted to be introduced into S. platensis without being digested would be increased.
BACKGROUND: The perturbed mitral leaflet geometry that leads to acute ischemic mitral regurgitation during acute left ventricular ischemia has not been quantified, nor is it known whether annuloplasty rings affect these detrimental changes in leaflet geometry. METHODS: Radiopaque markers were implanted on both mitral leaflets and around the anulus in 3 groups of sheep: one group without rings served as the control group (n = 7); the others underwent Duran (n = 6; Medtronic Heart Valve Division, Minneapolis, Minn) or Carpentier-Edwards Physio (n = 5; Baxter Cardiovascular Division, Santa Ana, Calif) ring annuloplasty. After recovery, 3-dimensional marker coordinates were obtained by means of biplane videofluoroscopy before and during acute posterolateral left ventricular ischemia. Leaflet geometry was defined by measuring distances between annular and leaflet markers and perpendicular distances to the leaflet markers from a best-fit annular plane. RESULTS: In all control animals, left ventricular ischemia was associated with acute ischemic mitral regurgitation and apical displacement (away from the annular plane) of the posterior leaflet edge and base markers by 0.6 +/- 0.4 mm (P =.01) and 0.7 +/- 0.2 mm (P <.001), respectively. The distance between the posterior leaflet markers and the mid-posterior anulus did not change significantly during ischemia. The anterior leaflet edge marker extended 1.0 +/- 0. 5 mm (P =.01) away from the mid-anterior anulus during ischemia, but compared with its nonischemic position, the anterior leaflet was not displaced apically away from the annular plane. In all animals in the Duran and Physio groups, leaflet geometry was unchanged during ischemia, and acute ischemic mitral regurgitation was not detected. CONCLUSION: Acute ischemic mitral regurgitation was associated with restricted motion of the posterior leaflet and extension of the anterior leaflet. Annuloplasty rings prevented these geometric perturbations of the mitral leaflets during acute left ventricular ischemia and preserved valvular competence.
Earthworm fibrinolytic enzyme component A, a protein which functions both as a direct fibrinolytic enzyme and a plasminogen activator, was purified from the earthworm Eisenia fetida. Diffraction-quality single crystals of the protein were grown by the hanging-drop vapour-diffusion technique with ammonium sulfate as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 40.6, b = 127.5, c = 129.2 A and three molecules per asymmetric unit. The data set reached a resolution of 1.95 A.
We sought to determine whether recombinant human thrombopoietin (TPO) acts synergistically with recombinant human erythropoietin (EPO) and/or recombinant human interleukin-3 (IL-3) on erythroid burst formation and granulocyte-macrophage colony formation from human bone marrow (BM). BM cells were from 5 adults and 15 children who underwent bone marrow examination because of a clinical suspicion of malignancy; their bone marrows as well as the complete blood counts were normal and were cultured in a methylcellulose system. TPO has a synergistic effect with EPO or EPO + IL-3 on erythropoiesis of human BM, as the addition of TPO to EPO significantly gave rise to more erythroid bursts (p = 0.0001) and the addition of TPO to EPO + IL-3 might give rise to more erythroid bursts (p = 0.05). TPO also has a synergistic effect with recombinant human granulocyte colony-stimulating factor (G-CSF) on myelopoiesis of human BM, since the addition of TPO to G-CSF gave rise to significantly more granulocyte-macrophage colonies (p = 0. 0001). Besides its well-known significant role in megakaryopoiesis, TPO also has synergistic effects on erythropoiesis and myelopoiesis.
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OBJECTIVE: To study the characteristics of optical coherence tomography (OCT) of primary open angle glaucoma (POAG), the difference of retinal nerve fiber layer (RNFL) thickness between normal persons and patients with POAG and the correlation between RNLF and visual field index. METHODS: Eighty-three cases (149 eyes) with POAG and 83 normal persons (150 eyes) were tested by OCT with circular scans around the optic nerve head (diameter = 3.46 mm) to observe the features of OCT. Statistic analysis was taken to compare the difference of RNFL thickness in quadrants and means between normal and glaucomatous group, and the difference of the thickness among the stages in POAG. Linear correlation and regression analysis was used to show the correlation between RNFL thickness and visual field index of 115 eyes of glaucomatous patients. RESULTS: The RNFL thickness measured by OCT in normal subjects is the thickest in superior and inferior quadrants, less in thickness in temporal and the thinnest in nasal quadrant. The curve showed double peaks. The RNFL of glaucomatous patients showed local thinness or defect, diffuse thinness or combination of the above two types. The mean RNFL thickness of normal group was (90.1 +/- 10.8) microm, (140.4 +/- 10.5) microm, (85.2 +/- 14.0) microm, (140.4 +/- 9.7) microm and (114.2 +/- 6.0) microm, of glaucomatous group was (56.0 +/- 31.0) microm, (81.0 +/- 36.3) microm, (47.1 +/- 27.5) microm, (73.4 +/- 38.4) microm and (64.6 +/- 28.8) microm in temporal, superior, nasal, inferior quadrant and the whole area, respectively. There is significant difference of RNFL thickness between the normal and glaucomatous group (P < 0.000), and there are significant differences among the three stages (early, developing and late) of glaucomatous group (P < 0.000). There is a close negative relationship between RNFL thickness and visual field index (r = -0.796, P < 0.0001). The sensitivity and specificity of RNFL thickness measured by OCT were 93.3% and 92.0%, respectively. CONCLUSION: OCT can quantitatively measure the RNFL thickness and show the difference of RNFL between normal persons and glaucomatous patients. The RNFL thickness gradually decreases while visual field defect increases with the development of POAG.
OBJECTIVE: To study the apoptosis in human gastric cancer cell MGC-803 induced by the extract of glycyrrhiza uralensis Fisch. METHODS: Apoptosis was detected by laser scanning confocal microscope, agarose gel electrophoresis and flow cytometry. The p53 gene expression was analyzed by double immunolabelling and immunohistochemistry technique. RESULTS: Chromatin condensation of different phases of apoptotic cells were observed by laser scanning confocal microscope, the percentage of apoptosis determined by flow cytometry was time- and dose-dependent, agarose gel electrophoresis of DNA exhibited obvious "ladder" in the cells treated with higher concentration of the extract of glycyrrhiza uralensis. The p53 gene expression was unchanged after treatment. CONCLUSION: Glycyrrhiza can induce human gastric cancer cell line MGC-803 to apoptosis by p53-independent pathway and can be used as a potential, natural apoptosis-inducing agent for gastric cancer therapy.
Several types of alkyd resins have been analyzed by simultaneous pyrolysis methylation gas chromatography mass spectrometry (SPM-GC-MS). The samples were mixed with tetramethylammonium hydroxide, and the process included simultaneous pyrolysis derivatization and mass spectrometry determination. SPM-GC-MS conditions: a vertical microfurnace-type pyrolyzer was directly attached to a gas chromatograph-mass spectrometer. About 20 ug of the mixed alkyd resin sample was introduced into the center of the pyrolyzer at 450 degrees C under the flow of helium carrier gas. The inlet mode was split with an injection interval of 10 s and the inlet pressure was 82.7 kPa. The gas chromatograph was fitted with a fused-silica capillary column ( SE-54 30 m x0.25 mm i.d. x 0.25 um). Temperature program settings were: initial temperature, 40 degrees C, hold 2 min; increase at 6 degrees C min 1 to 220 degrees C, hold 14 min; increase at 10 degrees C min 1 to 280 degrees C, hold 8 min. All pyrolysis products referred to were identified by mass spectrometry. The temperature of the ion source was 210 degrees C and that of the transfer line was 250 degrees C. The technique could give additional information about the composition of the dibasic acids, polyols, six types of drying oils, and modified alkyd resins. The method is sensitive, accurate, convenient, and involves minimal sample manipulation.
The crystal structure of R-Phycoerythrin (R-PE) from Polysiphonia urceolata has been refined to a resolution of 1.9 A, based on the atomic coordinates of R-PE determined at 2.8 A resolution, through the use of difference Fourier method and steorochemistry parameters restrained refinement with model adjustment according to the electron density map. Crystallographic R-factor of the refined model is 0.195 (Rfree = 0.282) from 8-1.9 A. High resolution structure of R-PE showed precise interactions between the chromophores and protein residues, which explained the spectrum characteristic and function of chromophores. Four chiral atoms of phycourobilin (PUB) were identified as C(4)-S, C(16)-S, C(21)-S, and C(20)-R. In addition to the coupling distances of 19 A to 45 A between the chromophores which were observed and involved in the energy transfer pathway, high resolution structure of R-PE suggested other pathways of energy transfer, such as the ultrashort distance between alpha140a and beta155. It has been proposed that aromatic residues in linker proteins not only influence the conformation of chromophore, but may also bridge chromophores to improve the energy transfer efficiency.
Icariin in Chinese traditional medicine was determined by an accurate and simple capillary zone electrophoresis method which used 30 mmol/L of borate solution containing 10% of acetonitrile as running buffer and needed no pretreatment.
A new separation medium, poly(N-isopropylacrylamide)-g-poly(ethyleneoxide) (PNI-PAM-g-PEO) solution, used for double-stranded (ds) DNA separation by capillary electrophoresis (CE) is presented. This type of grafted copolymer has a good self-coating ability for quartz capillary tubing and a slightly temperature-dependent viscosity-adjustable property, making it easier to use. One bp resolution was achieved within 12.5 min by using 8% w/v PNIPAM-gPEO in 1 x TBE (Tris-borate-ethylenediaminetetraaceticacid) buffer with an effective column length of 10 cm and an applied electric field strength of 200 V/cm. The PNIPAM-g-PEO solutions had a high sieving ability for relatively small sized DNAs with the relative standard derivation for the first 10 runs being less than 0.9% by using the same polymer solution. With 8% w/v PNIPAM-g-PEO solution in a 1.5 cm column and 2400 V as the running voltage, phiX174/HaeIII digest could be clearly separated within 24 s.
OBJECTIVE: To evaluate fossa-condylar-meniscus morphologic changes in patients with skeletal and dental Class III and Class II division 1 and 2 malocclusion to determine which type is related to internal derangement of the temporomandibular joint (TMJ) and whether the variation of TMJ structure is related to a particular type of malocclusion. MATERIALS AND METHODS: Seventy-two pretreatment orthodontic patients, ranging in age from 10 to 27 years, underwent examination of the right and left TMJs with corrected Schöller's position radiographs. Bilateral TMJ relationships of the fossa-condyle were examined through subjective evaluation and linear and area measurements. In addition, in 20 of the 72 patients, meniscus positions and morphologic changes were imaged with a 0.5 T sagittal magnetic resonance imaging system on the right and left TMJ. RESULTS: (1) The variation of condyle-fossa positions for identical types of malocclusion was very large. (2) Skeletal and functional Class III malocclusion patients demonstrated significantly more anteriorly positioned condyles. (3) Class II division 1 patients showed concentrically positioned condyles, but with slightly anterior displacement. (4) Class II division 2 patients demonstrated more posteriorly positioned condyles. (5) When condyles were in anterior or concentric positions, meniscus positions and morphology were normal and in concavoconcave shapes. (6) When condyles were in posterior positions, most meniscus positions were in normal or slightly anterior range and their shapes were also concavoconcave. The rest were significantly more anterior and their shapes were abnormal, as evidenced by thickened anterior bands. CONCLUSION: Class III and Class II division 1 malocclusion demonstrated normal structure and function of the TMJ. Class II division 2 malocclusion was obviously associated with abnormal structure and function of the TMJ.
OBJECTIVE: To observe the relationship between dynamic balance of the disturbance of serum lipoprotein and the 5 syndrome-types during Phlegm stasis syndrome (PSS) differentiation. METHODS: There were 171 patients, among them 81 cases were performed coronary arteriography (CAG). The serum lipoprotein electrophoretogram (SLPG) was examined by the double gradient polyacrylamide gel electrophoresis and the serum total cholesterol (TC) was determined with enzymatic method. RESULTS: (1) Comparing the PSS with the control group, there was significant difference in the abnormal items (P < 0.05-0.01). The blood stasis syndrome, PSS, and the Qi stagnation blood stasis syndrome were more than the phlegm syndrome and the non-PSS ones. The abnormal index of SLP (SLPI) had the following order: PSS(SLPI 1.941) > Qi stagnation blood stasis syndrome (1.901) > blood stasis syndrome (1.643) > phlegm syndrome (1.357) > non-PSS(1.105) and > the control syndrome (0.056). (2) The positive cases in CAG was 64 patients, in SLPG, it was 59 cases (92.19%). The negative in CAG was 17 cases, but the positive in SLPG, it was 14 cases (82.35%). (3) As the PSS developed further, the TC had an increasing tendency, but their average was less than 2100 mg/L, under the critical level. CONCLUSION: As the risk factor of the aged CHD, the TC was not an ideal criteria, the SPLG was an effective index. It was related with the PSS differentiation of the aged CHD.