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Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 343 records · Page 19Linked to original sources
PubMed2000

[The effect of integrin-like proteins on pollen germiantion and tube growth of Nicotiana tabacum].

The effects of antiserum against human VnR integrin and integrin antagonist GRGDSP peptides on Nicotiana tabacum pollen germination and tube growth both in in vitro and in semi-vivo conditions were studied. No obvious inhibitory effects on pollen germination and tube growth in vitro were observed when anti-VnR serum or GRGDSP peptides was added to BK culture medium, but the enhancement of pollen germination and tube growth in vitro promoted by calmodulin was depressed by adding anti-VnR serum or GRGDSP peptides to BK culture medium. In addition to that, pollen germination and tube growth on stigma, as well as tube growth in styles were also inhibited at some extent by treating stigma and microinjecting GRGDSP peptides or anti-VnR serum into styles. The role of integrin-like proteins in regulation of pollen germination and tube growth in situ was discussed.

Humans↗
PubMed2000

[Application of autotransfusion hemodilution in laryngectomy].

OBJECTIVE: To study the application and clinical significance of autotransfusion hemodilution in laryngectomy. METHOD: Autotransfusion hemodilution was adopted in 30 patients with III or IV stage laryngeal carcinoma during operation as the experimental group, and the blood transfusion only was adopted in the patients with excessively blood loss. The other 30 patients with the same stages of disease and the same kinds of operation were performed as the control group, without autotransfusion hemodilution and the blood transfusion was adopted if necessary. RESULT: Blood transfusion was necessary to be performed only in 8 patients of the experimental group, on the contrary, it was necessary in 19 of 30 patients of the control group (P < 0.01). There were no complications during the operations, and the postoperative complications were no significance (P > 0.05) between two groups. CONCLUSION: The application of autotransfusion hemodilution may be of help to a plenty of patients with laryngeal carcinoma in advanced stage to keep off the blood transfusion during laryngectomy.

Adult↗
PubMed2000

[Studies on the chemical constituents of Viscum coloratum].

Four compounds were isolated from Viscum coloratum (Kom.) Nakai by means of both solvent extraction and chromatographic separation methods. These constituents were identified through spectral analysis of IR, 1H-NMR. 13C-NMR and MS. They are syringin, oleanolic acid, beta-acetylamyrin and homoeriodictyol-7-beta-D-glucoside. It is the first separation from freshly collected Viscum colortum (Kom.) Nakai, which parasitizing on pear tree.

Glucosides↗
PubMed2000

[Re-evaluation of an embolic material for aneurysm cellulose acetate polymer].

OBJECTIVE: To re-evaluate the safety, effect, and pathological reactions of cellulose acetate polymer (CAP). METHODS: 30 right carotid arteries of rats were embolized and got two embolized vessels for histological study in each of the seven stages within four months. Fifteen canine aneurysmal models were created by transplantation of venous pouches. Twelve of them were occluded with CAP. Digital Subtraction Angiography (DSA) follow-ups of occluded aneurysmal models were carried out 1, 2 and 8 weeks after occlusion. One animal was sacrificed randomly at each stage for pathological study. RESULTS: Only five of the 12 aneurysmal models were completely or partially occluded within the patency of parent arteries within two months of observation after embolization with CAP. Stenosis of one branch of aneurysmal parent artery was occurred. The residual cavity of one partially occluded model artery was enlarged. Two models ruptured on four and five days after embolization. Three embolized models and their parent arteries were all occluded. PATHOLOGICAL FINDINGS: acute pathological reaction occurred within vessels embolized with CAP. Endothelial cell and basal membrane were damaged and vanished. Elastic lamina was exposed to arterial lumen and attached by thrombus layer. Fibrous cells and smooth muscle cells showed obvious degeneration. CAP and thrombus were gradually organized in two months after thrombosis. The orifices of aneurysmal models were covered with newly developed fibrous tissue and endothelial cells in two months after thrombosis. CONCLUSIONS: We think that acute chemical erosive effect of CAP was evident. A strong effect could lead to rupture of some of the CAP thrombosed aneurysmal models. Besides, stenosis or occlusion of the parent arteries could be induced in some cases after embolization with CAP. For the above shortcomings and limitations, it should be improved carefully before it is applied in clinic.

Aneurysm↗
PubMed2000

[Electrogastograph during interdigestive and digestive stages in patients with functional dyspepsia].

OBJECTIVE: To investigate the relationship between dynamic change of electrogastrogram (EGG) with motility index of antrum during migrating motor complex (MMC) cycle in healthy subjects and functional dyspepsia, and to verify whether a 100% coupling of electrical and mechanical events existed after meal. METHODS: Eleven healthy subjects (HS) and 14 patients with functional dyspepsia (FD) were studied. An 8-channel Dent-sleeve catheter was positioned under fluoroscopic guidance across antropyloroduodenal region and bipolar electrodes were attached to the skin corresponding to the location of antrum. Antropyloroduodenal pressure waves and electrical signals were transferred simultaneously to PC Polygraph (CTD) and recorded for 3 hours preprandially and 2 hours after ingestion of 40 g solid meal (336 kJ). The power of EGG and motility index (MI) of antral contractions were calculated as the area under curve (AUC) by a build-in computer program. RESULTS: The power increases of EGG increased significantly in phase II (P < 0.01), phase III (P < 0.01) and after meal (P < 0.01) compared with phase I in HS, however, this dynamic increase was not found in FD. The power of EGG was positively correlated with the motility index of antrum both in HS (r = 0.87, P < 0.01) and in FD (r = 0.79, P < 0.01) during the interdigestive period. A significant increase of EGG power after meal was found in HS, which corresponded to the degree of phase III and kept stable for the whole postprandial period. In contrast, power increase was not found in FD except during 30 min after test meal. CONCLUSIONS: Prolonged cutaneous EGG recording can reflect the periodic variation of MMC cycle. EGG response in HS but not in FD after meal is characterized as persistent increase which is corresponded to phase III.

Adult↗
PubMed2000

[Mechanisms of opioid receptor-induced elevation in intracellular calcium by confocal laser scanning microscopy].

OBJECTIVE: To determine the acute and chronic effects of opioid receptor agonists on the intracellular free calcium concentration ([Ca2+]i) in NG-LNCXiNOS cells, stably expressing iNOS gene, and regulation of G-protein on opioid-induced response in [Ca2+]i. METHODS: A single cell [Ca2+]i is measured by confocal laser scanning microscopy using Ca(2+)-sensitive dye Fluo-3 as an new calcium fluorescent probe. RESULTS: DPDPE(D-Pen2, D-Pen5-enkephalin), a delta-opioid receptor agonist, and morphine acutely induced the increase in [Ca2+]i of NG-LNCXiNOS cells. The elevation in [Ca2+]i by DPDPE could be abolished with naloxone. Pretreatment of the cells with pertussis toxin (PTX) at 100 ng/ml for 24 hours almost completely blocked morphine-evoked response. In contrast to acute effect of opioid agonists on [Ca2+]i, the cells exposed to 1 mumol/L DPDPE or 10 mumol/L morphine for 48 hours also appeared to raise [Ca2+]i. However, the elevation in [Ca2+]i was not greater than that caused by acute effect of DPDPE or morphine. After cell "withdrawal" was precipitated by the addition of 10 mumol/L naloxone, the increase in [Ca2+]i could further be intensified. CONCLUSIONS: The opioid agonist-induced increase in [Ca2+]i is mediated by opioid receptor and regulated though PTX-sensitive G-protein. The attenuation of this response in chronically treated cells with opioid agonist is associated with receptor desensitization.

Calcium↗
PubMed2000

[Vibrational frequencies study of the hydroxy-benzoquinones].

In this paper, we report the Ab initio calculation and experimental investigation of the vibrational frequencies of 4,5-dihydroxy-1,2-benzoquinone and 2,5-dihydroxy-1,4-benzoquinone. The main IR and Raman absorption bands of them have been assigned, learned from other strong points to offset one weakness, by combination the program Gaussian 94 and MOPAC. The difference in absorption bands between them has been discussed.

Benzoquinones↗
PubMed2000

[Influence on luminescence of Tb o-aminobenzolate complexes by second ligand].

Two Tb o-aminobenzolate complexes with different second ligands (phenanthroline and triphenyl phasphine oxide) were synthesized. Their structures and fluorescent properties were investigated by fluorescence spectroscopy and FTIR spectroscopy. The results indicate that the second ligand affected on the complexes luminescence by changing its structure.

Chelating Agents↗
PubMed2000

[FTIR study on the structures of bilirubin in solution].

The structures of bilirubin in solid-state, in HCCl3 and DMSO solution are investigated by FTIR spectroscopy. The results indicate that bilirubin have very different structures in solid-state and in solutions. The results also demonstrate that the structures vary in different solvents. There are six H-bonds in bilirubin molecule in solid-state, four in bilirubin molecule in HCCl3 solution and one in bilirubin molecule in DMSO solution.

Animals↗
PubMed2000

[The study of the microwave reaction of stearic acid and pentyl amine].

In this study, the microwave reaction of stearic acid and pentyl amine was investigated by FTIR spectroscopy. The results indicated that after mixing the two reactants together, pentyl ammonium stearate was created and it formed acid-salt structure with the stearic acid remained. The results also demonstrated that under microwave radiation, the pentyl ammonium stearate could be not only decomposed, but also dehydrated to form stearic pentyl amide. It suggested that the microwave radiation was an ideal technique to make this chemical reaction much faster and much more thorough.

Amines↗
PubMed2000

[Synthesis and characterization of the oxidation product of the 1, 2, 3-trihydroxybenzene and its metallic complexes].

The oxidation reaction mechanism of the 1,2,3-trihydroxybenzene was studied by the Ab initio calculation of the quantum chemistry. The derivative of the hydrazine and THBO(the reaction product of the 1,2,3-trihydroxybenzene and H2O2) and its metal complexes were synthesized and characterized by the IR, Raman spectrum and thermogravimetric analysis. The composition of these complexes and the possible structure of THBO were confirmed.

Chelating Agents↗
PubMed2000

[FTIR and fluorescence studies on the europium complexes of multiple ligands].

A series of EuA(m).nB complexes with different molar ratio of ligands and various concentrations of protecting agent were synthesized (A is thenoyltrifluoroacetone, B is a kind of P = O group compound). The properties of these complexes were investigated by FTIR and fluorescence spectroscopy. The fluorescent intensity of complex is related to the reaction condition, the components of complexes.

Chelating Agents↗
PubMed2000

[Simultaneous determination of tryptophan and tyrosine by second order derivative fluorimetry].

A new method of second order derivative fluorimetry for the simultaneous determination of tryptophan and tyrosine is described. The measurement of emission spectra is carried out with excitation at 221 nm in a KH2PO4-NaOH buffer solution (pH = 7.4). The second-derivative peak is at 318 nm and 283 nm for tryptophan and tyrosine respectively. The two amino acids can be determined directly from corresponding second order derivative signals. Linear regression equation of the calibration graph is c = 0.000 7H-0.004, with a correlation coefficient of linear regression of 0.9964 for tryptophan and c = 0.001 2H-0.0040, with a correlation coefficient of linear regressin of 0.9971 for tyrosine. The linear ranges of determination of tryptophan and tyrosine are from 0.004 to 0.200 microgram.mL-1 and from 0.002 to 0.025 microgram.mL-1, respectively. Effects of pH, temperature and foreign ions on the determination of tryptophan and tyrosine have been examined. Recovery is from 92.0% to 104% for tryptophan and 98.7% to 102.0% for tyrosine, and relative standard deviation of 3.5% and 2.8%, respectively.

Fluorometry↗
PubMed1999

Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis.

Apoptosis is a programmed cell death mechanism to control cell number in tissues and to eliminate individual cells that may lead to disease states. The present study investigates chromium(VI) (Cr(VI))-induced apoptosis and the role of reactive oxygen species (ROS) and p53 in this response. Treatment of human lung epithelial cells (A549) with Cr(VI) caused apoptosis as measured by DNA fragmentation, mitochondria damage, and cell morphology. Cr(VI)-induced apoptosis is contributed to ROS generation, resulting from cellular reduction of Cr(VI) as measured by flow cytometric analysis of the stained cells, oxygen consumption, and electron spin resonance spin trapping. Scavengers of ROS, such as catalase, aspirin, and N-acetyl-L-cysteine, decreased Cr(VI)-induced apoptosis, whereas NADPH and glutathione reductase, enhancers of Cr(VI)-induced ROS generation, increased it. p53 is activated by Cr(VI), mostly by ROS-mediated free radical reactions. Cr(VI)-induced ROS generation occurred within a few minutes after Cr(VI) treatment of the cells, whereas p53 induction took at least 5 h. The level of Cr(VI)-induced apoptosis was similar in both p53-positive cells and p53-negative cells independent of p53 status in the early stage (0-3 h) of Cr(VI) treatment. However, at the later stage (3-24 h), the level of the apoptosis is higher in p53-positive cells than in p53-negative cells. These results suggest that ROS generated through Cr(VI) reduction is responsible to the early stage of apoptosis, whereas p53 contributes to the late stage of apoptosis and is responsible for the enhancement of Cr(VI)-induced apoptosis at this stage.

Apoptosis↗
PubMed1999

Assembly of AUF1 oligomers on U-rich RNA targets by sequential dimer association.

Many labile mammalian mRNAs are targeted for rapid cytoplasmic turnover by the presence of A + U-rich elements (AREs) within their 3'-untranslated regions. These elements are selectively recognized by AUF1, a component of a multisubunit complex that may participate in the initiation of mRNA decay. In this study, we have investigated the recognition of AREs by AUF1 in vitro using oligoribonucleotide substrates. Gel mobility shift assays demonstrated that U-rich RNA targets were specifically bound by AUF1, generating two distinct RNA-protein complexes in a concentration-dependent manner. Chemical cross-linking revealed the interaction of AUF1 dimers to form tetrameric structures involving protein-protein interactions in the presence of high affinity RNA targets. From these data, a model of AUF1 association with AREs involving sequential dimer binding was developed. Using fluorescent RNA substrates, binding parameters of AUF1 dimer-ARE and tetramer-ARE equilibria were evaluated in solution by fluorescence anisotropy measurements. Using two AUF1 deletion mutants, sequences C-terminal to the RNA recognition motifs are shown to contribute to the formation of the AUF1 tetramer.ARE complex but are not obligate for RNA binding activity. Kinetic studies demonstrated rapid turnover of AUF1.ARE complexes in solution, suggesting that these interactions are very dynamic in character. Taken together, these data support a model where ARE-dependent oligomerization of AUF1 may function to nucleate the formation of a trans-acting, RNA-destabilizing complex in vivo.

Base Sequence↗
PubMed1999

Molecular cloning and characterization of human trabeculin-alpha, a giant protein defining a new family of actin-binding proteins.

We describe the molecular cloning and characterization of a novel giant human cytoplasmic protein, trabeculin-alpha (M(r) = 614,000). Analysis of the deduced amino acid sequence reveals homologies with several putative functional domains, including a pair of alpha-actinin-like actin binding domains; regions of homology to plakins at either end of the giant polypeptide; 29 copies of a spectrin-like motif in the central region of the protein; two potential Ca(2+)-binding EF-hand motifs; and a Ser-rich region containing a repeated GSRX motif. With similarities to both plakins and spectrins, trabeculin-alpha appears to have evolved as a hybrid of these two families of proteins. The functionality of the actin binding domains located near the N terminus was confirmed with an F-actin binding assay using glutathione S-transferase fusion proteins comprising amino acids 9-486 of the deduced peptide. Northern and Western blotting and immunofluorescence studies suggest that trabeculin is ubiquitously expressed and is distributed throughout the cytoplasm, though the protein was found to be greatly up-regulated upon differentiation of myoblasts into myotubes. Finally, the presence of cDNAs similar to, yet distinct from, trabeculin-alpha in both human and mouse suggests that trabeculins may form a new subfamily of giant actin-binding/cytoskeletal cross-linking proteins.

Amino Acid Sequence↗
PubMed1999

Early repair treatment of electrical burns and recovery of tendons and nerves. Report of 194 operations.

A new approach to treatment of electrically burned tendons and nerves by primarily covering with skin or myocutaneous flaps is recommended. Between 1964 and 1989, 194 operations using the new approach were performed on 147 patients, of which 179 operations were successful and only 15 procedures resulted in infection. Among 42 cases involving the wrist, the rate of functional recovery of the electrically burned tendons was 97.6%; the rate of recovery in 21 cases of electrically burned peripheral nerves was 80.9%.

Burns, Electric↗