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Biomedical subjects

R Yang

Publications and source records attributed to R Yang.

At least 55 records · Page 3Linked to original sources
PubMed2001

Fluorometric study of the inclusion interaction of beta-cyclodextrin derivatives with tetraphenylporphyrin and its analytical application.

The effects of native beta-cyclodextrin (beta-CD) and four kinds of alkylated beta-cyclodextrin (beta-CDs), i.e. heptakis (2,6-di-O-isobutyl-beta-cyclodextrin) (I), heptakis (2,6-di-O-octyl-beta-cyclodextrin) (II), heptakis (2,6-di-O-dodecyl-beta-cyclodextrin) (III), and heptakis (2,6-di-O-hexadecyl-beta-cyclodextrin) (IV), on the fluorescence behaviors of tetraphenylporphyrin (TPP) are investigated. An obvious fluorescence enhancement is observed from TPP by using alkylated derivatives compared to that obtained in beta-CD aqueous or in water. A 114-N fluorescence emission intensity enhancement is found for the complex with 2,6-di-O-octyl-beta-cyclodextrin relative to the free analyte. The exact stoichiometric ratios and the formation constants of the inclusion complexes have been examined by application of curve fitting method. The linear calibration plots between fluorescence intensity and TPP concentration are determined in the 1.14 x 10(-8)-5.06 x 10(-6) mol l(-1) range.

Alkylation↗
PubMed2001

Transcatheter closure of secundum atrial septal defect with a new self-expanding nitinol double disk device (Amplatzer device): experience in Nanjing.

PURPOSE: Various devices have been developed for the transcatheter closure of secundum atrial septal defect (ASD II) to avoid the morbidity, discomfort, and thoracotomy scar associated with surgical closure. The purpose of this study was to evaluate the safety and efficacy of the Amplatzer septal occluder for transcatheter closure of ASD II. PATIENTS AND METHODS: Only patients who were clinically diagnosed with ASD II were selected. The anatomy of ASD had to meet certain echocardiographic criteria. Under the guidance of echocardiography and fluoroscopy, the implantation of the device was accomplished as recommended by the manufacturer. RESULTS: Thirty patients (median age 18.4 years) with an ASD II underwent transcatheter closure. Procedure time ranged from 30-200 minutes and fluoroscopy time from 10-50 minutes. The diameter of the ASD measured by echocardiography ranged from 13-25 mm, while both the stretched diameters of the ASDs and the sizes of the devices ranged from 18-34 mm. The successful placement rate was 100%. The residual shunt rate was 100% immediately after device implantation and 10% after 24 hours. After 3 months, 3.3% of the patients had a (trivial) residual shunt. The device did not affect the surrounding structures of ASD. No embolization of the device occurred. CONCLUSION: The Amplatzer device designed for the closure of ASD II can be implanted easily and also is retrievable. Due to a low ratio of residual shunt and few complications, this device is a good choice for transcatheter closure of ASD II. Long-term follow-up will be required for widespread clinical use.

Adolescent↗
PubMed2001

Modeling and mutational analysis of a putative sodium-binding pocket on the dopamine D2 receptor.

A homology model of the dopamine D2 receptor was constructed based on the crystal structure of rhodopsin. A putative sodium-binding pocket identified in an earlier model (PDB ) was revised. It is now defined by Asn-419 backbone oxygen at the apex of a pyramid and Asp-80, Ser-121, Asn-419, and Ser-420 at each vertex of the planar base. Asn-423 stabilizes this pocket through hydrogen bonds to two of these residues. Highly conserved Asn-52 is positioned near the sodium pocket, where it hydrogen-bonds with Asp-80 and the backbone carbonyl of Ser-420. Mutation of three of these residues, Asn-52 in helix 1, Ser-121 in helix 3, and Ser-420 in helix 7, profoundly altered the properties of the receptor. Mutants in which Asn-52 was replaced with Ala or Leu or Ser-121 was replaced with Leu exhibited no detectable binding of radioligands, although receptor immunoreactivity in the membrane was similar to that in cells expressing the wild-type D2L receptor. A mutant in which Asn-52 was replaced with Gln, preserving hydrogen-bonding capability, was similar to D2L in affinity for ligands and ability to inhibit cAMP accumulation. Mutants in which either Ser-121 or Ser-420 was replaced with Ala or Asn had decreased affinity for agonists (Ser-121), but increased affinity for the antagonists haloperidol and clozapine. Interestingly, the affinity of these Ser-121 and Ser-420 mutants for substituted benzamide antagonists showed little or no dependence on sodium, consistent with our hypothesis that Ser-121 and Ser-420 contribute to the formation of a sodium-binding pocket.

Amino Acid Sequence↗
PubMed2001

Augmentation of human immunodeficiency virus type 1 subtype E (CRF01_AE) multiple-drug resistance by insertion of a foreign 11-amino-acid fragment into the reverse transcriptase.

A human immunodeficiency virus type 1 (HIV-1) subtype E (CRF01_AE) variant (99JP-NH3-II) possessing an in-frame 33-nucleotide insertion mutation in the beta3-beta4 loop coding region of the reverse transcriptase (RT) gene was isolated from a patient who had not responded to nucleoside analogue RT inhibitors. This virus exhibited an extremely high level of multiple nucleoside analog resistance (MNR). Neighbor-joining tree analysis of the pol sequences indicated that the 99JP-NH3-II variant had originated from the swarm of drug-sensitive predecessors in the patient. Population-based sequence analyses of 82 independently cloned RT segments from the patient suggested that the variants with the insertion, three or four 3'-azido-3'-deoxythymidine resistance mutations, and a T69I mutation in combination had strong selective advantages during chemotherapy. Consistently, in vitro mutagenesis of a drug-sensitive predecessor virus clone demonstrated that this mutation set functions cooperatively to confer a high level of MNR without deleterious effects on viral replication capability. Homology modeling of the parental RT and its MNR mutant showed that extension of the beta3-beta4 loop by an insertion caused reductions in the distances between the loop and the other subdomains, narrowing the template-primer binding cleft and deoxynucleoside triphosphate-binding pocket in a highly flexible manner. The origin of the insert is elusive, as every effort to find a homologue has been unsuccessful. Taken together, these data suggest that (i) HIV-1 tolerates in vivo insertions as long as 33 nucleotides into the highly conserved enzyme gene to survive multiple anti-HIV-1 inhibitors and (ii) the insertion mutation augments multiple-drug resistance, possibly by reducing the biochemical inaccuracy of substrate-enzyme interactions in the active center.

Adult↗
PubMed2001

Two apical multidrug transporters, P-gp and MRP2, are differently altered in chronic renal failure.

Tubular function is altered in chronic renal failure (CRF). Whether drug secretion by renal tubules is modified in CRF is questioned because of frequent accumulation of various toxins in CRF. This function mainly involves ATP-dependent drug transporters, particularly P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) 2, both present in apical membrane of epithelial cells. The present study was aimed at determining the changes in P-gp and MRP2 expression induced by experimental CRF in kidney and liver. The relationship between MRP2 and glutathione metabolism changes was examined because MRP2 transports GSSG and glutathione conjugates. Rats underwent either 80% subtotal nephrectomy (Nx) or sham operation, and determinations were performed 3 and 6 wk later. CRF induced a 70--200% rise in protein and mRNA expression of MRP2 after 3 and 6 wk post-Nx in remnant kidney and after 6 wk in liver. However, P-gp expression was unchanged by CRF. Relative to whole kidney mass, total MRP2 levels decreased by only 27% in Nx rats whereas total P-gp levels were reduced by 60%. Renal GSSG and total glutathione levels were increased by 30% in Nx rats, but glutathione-S-transferase (GST) activity was normal; liver GSSG levels and GST activity were reduced in Nx rats. In conclusion, CRF resulted in specific overexpression of MRP2 in kidney and liver. This could be an adaptative response to some elevated circulating toxins. The later MRP2 induction and different glutathione changes in liver compared with kidney suggest different mechanisms for MRP2 induction and/or action in these two tissues.

5'-Nucleotidase↗
PubMed2001

Iron chlorin e6 scavenges hydroxyl radical and protects human endothelial cells against hydrogen peroxide toxicity.

Iron chlorin e6 (FeCe6) has recently been proposed to be potentially antimutagenic and antioxidative. However, the antioxidant property of FeCe6 has not been elucidated in detail. In this study, we investigated the ability of FeCe6 to scavenge hydroxyl radical and to protect biomolecules and mammalian cells from oxidative stress-mediated damage. In electron spin resonance (ESR) experiments, FeCe6 showed excellent hydroxyl radical scavenging activity, whereas its iron-deficient molecule, chlorin e6 (Ce6) showed little effect. FeCe6 also significantly reduced hydroxyl radical-induced thiobarbituric acid reactive substance (TBARS) formation and benzoate hydroxylation in a dose-dependent manner. The rate constant for reaction between FeCe6 and hydroxyl radical was measured as 8.5 x 10(10) M(-1) s(-1) by deoxyribose degradation method, and this value was much higher than that of most hydroxyl radical scavengers. Superoxide dismutase (SOD) activity of FeCe6 was also confirmed by ESR study and cytochrome c reduction assay, but its in vitro activity appeared to be less efficient in comparison with other well-known SOD mimics. In addition, FeCe6 appreciably diminished hydroxyl radical-induced DNA single-strand breakage and protein degradation in Fe-catalyzed and Cu-catalyzed Fenton systems, and it significantly protected human endothelial cells against hydrogen peroxide (H2O2) toxicity. These results suggest that FeCe6 is a novel hydroxyl radical scavenger and may be useful for preventing oxidative injury in biological systems.

Antioxidants↗
PubMed2001

Resonance Rayleigh method for the determination of proteins with Orange G.

In pH 0.6 - 2.0 HCl-sodium acetate buffer solution, proteins react with an acidic monoazo dye such as Orange G, Methyl Orange, Methyl Red and Orange IV to form a combination product. This results in a significant enhancement of resonance Rayleigh scattering (RRS) and a new RRS spectrum appears. Owing to the fact that Orange G-protein system is the most sensitive, it was taken as an example to study. The RRS spectral characteristics of its combination product and the optimum condition for the reaction were investigated. The intensity of RRS is directly proportional to the concentration of protein in the range of 0 - 5.0 microg/mL. The method has high sensitivity; its detection limits are 2.6 ng/mL for BSA, 3.4 ng/mL for HAS and 7.1 ng/mL for alpha-chymotrypsin, respectively. A new method for the determination of trace amounts of proteins on the basis of RRS spectra has been developed.

Algorithms↗
PubMed2001

[Effect of vitamin E on morphological variation of retinal ganglion cells after microwave radiation].

To determine the morphological variation in the primary cultured pig retinal ganglion cells induced by microwave and the protection of VE can supply some experiment foundation for study of effect of microwave and its protection. Retinal ganglion cells of pig were cultured in vitro and added VE of different concentration, Each group was taken after 30 mW/cm2 microwave intensity radiated for 1 h in shielded room by 2450 MHz continuous wave physiotherapy machine. Immediately after radiation, the morphological variation of cells was observed by optics microscope and transmission electronic microscope. The result showed that a portion of cells congregated, with their axon disappeared after radiation. Mitochondria and endoplasmic reticulum are detected swelling by transmission electronic microscope. The results showed that A poptosis cells can be observed. Cells of VE added groups had not obvious changes with optics microscope, but could be found that mitochondria swelling lightly and integrate mitochondria cristae by transmission electronic microscope. The results showed that microwave induced the morphological damage in primary cultured retinal ganglion cells, VE could reduced the damage of retina ganglion cells by microwave in some extent.

Animals↗
PubMed2001

[A case-control study on attempted suicide].

OBJECTIVE: To assess the independent risk factors of attempted suicide and the importance of mental illness as a risk factor. METHODS: Detailed assessments of 152 suicide attempters treated in general hospitals and 152 matched controls through questionaires. RESULTS: The rate of mental illness in the suicide attempters' group was significantly higher than that in the control group (37.7% versus 4.0%, paired Chi square = 45.45, P < 0.001). Conditional logistic regression identified three independent predictors of suicidal behavior: severe acute stress (OR = 67.47, 95% CI: 8.85-514.56), presence of mental illness (OR = 13.85, 95% CI: 2.01-95.55), and immense psychological effect of negative life events in the prior year (OR = 5.30, 95% CI: 1.12-26.08). CONCLUSION: Mental illness is an important risk factor of attempted suicide, but not an essential pre-condition of suicide attempts. It is important to establish a national suicide prevention plan that which is pertinent to the conditions in China.

Adult↗
PubMed2001

[The change of immunocompetent cells in normal human dental pulp during development of immature permanent teeth].

OBJECTIVE: To study changes of several immunocompetent cells (ICCs), namely, pulpal dendritic cells (PDCs), T lymphocytes, B lymphocytes, and endothelial cells, in normal human dental pulp according to different development stage of completely erupted but not fully developed premolar in order to provide evidence for local immune defense mechanisms during development of immature permanent teeth. METHODS: Based on the dental development status, the pulp tissue was classified into the following groups: big trumped-shaped group, small trumped-shaped group and closed group. The above mentioned cells were immunohistochemically examined by use of HLA-DR, CD45RO, CD20 mouse anti-human monoclonal antibodies. Double-staining was also done by use of the former two antibodies. The number of positively stained cells or blood vessels was counted and statistically analyzed. RESULTS: 1. Normal dental tissue of three groups all expressed HLA-DR+ PDCs. Among three groups, the number of HLA-DR+ cells in big trumped-shaped group was more than that of small trumped-shaped group and closed group. 2. There was no significant difference of positive blood vessel rate of HLA-DR expressing endothelial cells among three groups. 3. There was no significant difference of CD45RO+ T cells among three groups. 4. By use of double-labeling immunohistochemistry, HLA-DR+ PDCs and CD45RO+ T cells were found to be rarely in contact with each other. Correlation analysis between two kinds of cells did not indicate the linear relationship. CONCLUSIONS: The number of PDCs tends to decrease with increasing age in the developing dental pulp of human normal tooth, other ICCs are not related with dental development.

Adolescent↗
PubMed2001

Effects of acute or prolonged exposure to leptin on hepatic glucose oxidation.

OBJECTIVE: To observe the short-term and long-term effects of leptin on hepatic glucose oxidation and glucokinase gene expression. METHODS: Rat hepatic cell line BRL was incubated with leptin of different doses (range from 10 ng/ml-200 ng/ml) for 1 h or 24 h. Glucose oxidation was determined by liquid scintillation counting. Glucokinase gene expression (corrected by beta-actin) was determined by reverse transcription semi-quantitative polymerase chain reaction. RESULTS: Treatment with leptin 10 ng/ml for 1 h had no significant effects on glucose oxidation in hepatic cells. However, at the doses ranging from 50 ng/ml to 200 ng/ml, leptin significantly inhibited glucose oxidation. These effects disappeared when the hepatic cells were exposed to leptin for 24 h. Glucokinase mRNA expression was reduced significantly after both 1 h and 24 h exposure to leptin (100 ng/ml) as compared to that of the control group. CONCLUSION: A low dose of leptin has no significant effect on glucose oxidation in hepatic cells. A relatively high dose of leptin has an acute inhibitory effect on the glucose oxidation in hepatic cells. This effect may likely involve the inhibition of glucokinase gene expression. The inhibitory effect on glucose oxidation is transient and disappears with prolonged exposure time.

Animals↗
PubMed2001

The affects of acupuncture at sibai and neiting acupoints on gastric peristalsis.

The frequency and amplitude of gastric peristaltic wave were significantly changed in 15 subjects when Sibai (ST 2) and Neiting (ST 44) acupoints of the Stomach Channel of Foot-Yangming were punctured. The results demonstrate that these acupoints are effective for treatment of stomach diseases, providing an experimental basis for the theory of channels and collaterals.

Acupuncture Points↗
PubMed2001

[A study of millimeter wave's clinical and immunological effects on oral lichen planus patients].

OBJECTIVE: The aim of this study is to observe clinical effects of the millimeter wave on oral lichen planus (OLP) and its immune mechanisms. METHODS: 30 patients with OLP were randomized into the millimeter wave group and the control group. 15 patients in the millimeter wave group were treated with millimeter wave (7.1 mm, 43 GHz, 10 mW/cm2) radiation, while the other 15 patients in the control group were just given soothing treatment. Either before or after the therapy procedure, the clinical manifestations and the T-cell sub-grouping in the peripheral circulation of each patient were double-blindly evaluated. RESULTS: The pain-soothing effect in the patients treated with millimeter wave was much more obvious than that of the control group (P < 0.01). The peripheral blood CD8+ percent of millimeter wave group decreased greatly (P < 0.05), while no obvious CD8+ change was observed in the control group (P > 0.05). The millimeter wave group's CD4+/CD8+ improvement was also much more obvious than that of the control group (P < 0.05), and its CD4+/CD8+ ratio was completely recovered to the normal level. CONCLUSION: Millimeter wave can effectively relieve OLP patients' pain, and can regulate OLP patients' cellular immune condition. Millimeter wave might provide a new treatment method for OLP.

Adult↗
PubMed2001

[Determination of DNA-DNA homology among Pseudomonas cocovenenans subsp. farinofermentans with microdilution plate hybridization method].

The DNA-DNA homologies among Pseudomonas cocovenenans subsp. farinofermentans and 11 species in genus Burkholderia were determined with microdilution plate hybridization method. The results showed: the homologies among P. cocovenenans subsp. farinofermentans, B. gladioli and B. cocovenenans were all over 75%. It was advised that these three species were synonym, and should be renamed as Burkholderia gladioli.

Burkholderia↗
PubMed2001

[Rapid detection of enterohemorrhagic Escherichia coli in food with multiplex PCR assay].

Rapid detection of enterohemorrhagic Escherichia coli (EHEC) in food was achieved by using multiplex PCR assay. The assay was designed to amplify the 1109, 302 and 228 bp regions of corresponding virulence genes eaeA, hlyAB, slt1 and/or slt2, by using specific primers for each one reaction. In 60 EHEC and other strains, the above three virulence gene sequences were co-amplified from DNA isolated from 12 EHEC O157:H7 strains, 1 O26:H11 strain and 1 O111:H8 strain; eaeA sequence was amplified from DNA isolated from 2 EAEC strains; slt1/2 sequence was amplified from DNA isolated from 1 VTEC strain. No specific amplification product was produced from other 43 non-EHEC strains. For the detection of EHEC in food, results could be obtained within 8 hrs, and the sensitivity of assay was less than or equal to 1.6 cfu/g(ml) of food. The method was applied to 126 food samples, and EHEC was detected in 3 samples.

Animals↗
PubMed2001

[ATR-FTIR studies on the packing film].

FTIR and ATR-FTIR of the packing film have been studied. The dimension of thickness is about 0.034 m/m, the right and wrong sides of this packing film is composed of polypropylene and polyethylene glycol terephthalate, respectively.

English Abstract↗