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Yan Gao

Publications and source records attributed to Yan Gao.

At least 91 records · Page 5Linked to original sources
PubMed2004

Structural properties of silver nanorods with fivefold symmetry.

The microstructural features of silver nanorods with the average length of 50 microm and diameters of around 100 nm have been investigated by means of SEM, X-ray diffraction, and transmission-electron microscopy (TEM). Silver nanorods in general have a pentagonal shape with a remarkable fivefold symmetry as revealed in cross-section observations. The fivefold axis, i.e. the growth direction, normally goes along the [110]-zone axis direction of the basic fcc Ag-structure. The twinning relationships and relevant twin boundaries among the five subunits in the pentagonal nanorod have been examined by high-resolution TEM and selected-area electron diffraction. Defects and stacking faults in this kind of nanorods have been briefly analyzed.

Journal Article↗
PubMed2004

Crystal structure of the TAO2 kinase domain: activation and specificity of a Ste20p MAP3K.

TAO2 is a mitogen-activated protein kinase kinase kinase (MAP3K) that doubly phosphorylates and activates the MAP kinase kinases (MAP2Ks) MEK3 and MEK6. The structure of the kinase domain of TAO2 (1-320) has been solved in its phosphorylated active conformation. The structure, together with structure-based mutagenic analysis, reveals that positively charged residues in the substrate binding groove mediate the first step in the dual phosphorylation of MEK6, on the threonine residue in the motif DS*VAKT*I (*denotes phosphorylation site) of MEK6. TAO2 is a Ste20p homolog, and the structure of active TAO2, in comparison with that of low-activity p21-activated protein kinase (PAK1), a Ste20p-related MAP4K, reveals how this group of kinases is activated by phosphorylation. Finally, active TAO2 displays unusual interactions with ATP, involving, in part, a subgroup-specific C-terminal extension of TAO2. The observed interactions may be useful in making specific inhibitors of TAO kinases.

Adenosine Triphosphate↗
PubMed2004

The prevalence and target antigens of antithyroid drugs induced antineutrophil cytoplasmic antibodies (ANCA) in Chinese patients with hyperthyroidism.

OBJECTIVE: Antithyroid drugs such as propylthiouracil (PTU) and methimazole (MMI) are common medications in Chinese patients with hyperthyroidism and PTU-induced antineutrophil cytoplasmic antibody (ANCA) positive vasculitis has been reported. The current cross-sectional study aimed to investigate the prevalence and the target antigens of ANCA in Chinese patients with hyperthyroidism pre- and post-antithyroid medication therapy. METHODS: Sera from 216 patients with hyperthyroidism in our hospital were collected from January to July in 2002. Patients were divided into four groups: untreated (n = 34); treated with PTU (n = 62); treated with MMI (n = 77); and treated with both PTU and MMI (n = 43). Indirect immunofluorescence (IIF) assay was used to detect ANCA and ANA. Antigen-specific ELISAs were used to detect antigen specificities. The known antigens included myeloperoxidase (MPO), proteinase 3 (PR3), human leukocyte elastase (HLE), lactoferrin, bactericidal/permeability-increasing protein (BPI), cathepsin G and azurocidin. RESULTS: 33/216 sera were IIF positive, 20 of the 33 samples were ANCA positive, 11 samples were ANA positive, and two samples were both P-ANCA and ANA positive. The prevalence of positive ANCA in patients receiving PTU (14/62, 22.6%) was significantly higher than that of untreated patients (1/34, 2.9%) and patients treated with MMI (0/77, 0), P < 0.017. Of the 22 IIF-ANCA positive samples, 12 (54.5%) sera recognized lactoferrin, seven (31.8%) sera recognized HLE, four sera recognized MPO and azurocidin respectively, three sera recognized PR3 and cathepsin G respectively, and one serum recognized BPI. Six of the 22 (27.3%) patients with ANCA positive had clinical evidence of vasculitis. All patients with MPO-ANCA and two of the three patients with PR3-ANCA had clinical vasculitis. CONCLUSION: PTU is associated with the production of ANCA in patients with hyperthyroidism. PTU-induced ANCA are due to polyclonal activation of B cells. Anti-MPO and anti-PR3 antibodies may associate the occurrence of clinical vasculitis.

Adult↗
PubMed2004

[Establishment of cultivating technology of dental follicle cells of rat and their identifying].

OBJECTIVE: To establish a method for culturing dental follicle cells of rat and observe the growth characteristics of the cultured cells in vitro. METHODS: Dental follicle and associated enamel organs were dissected from the first and second mandibular molars of 6-7-day-old rats, and then cultured in vitro. Purified dental follicle cells derived from the third or the fourth passage cells were utilized in the following experiments. The shape and ultrastructure of dental follicle cells were observed by light-microscopy and transmission electron microscopy. Immunocytochemistry was used to detect the expression of vimentin, type I collagen and fibronectin. RESULTS: The cultured cells were fibroblastic in shape, elongate with processes, and transmission electron microscopy revealed that they contained electron-dense granules, an abundant rough endoplasmic reticulum, but did not form desmosomes. Vimentin, type I collagen and fibronectin were present in dental follicle cell. CONCLUSION: The dental follicle cells of rat could be successfully cultured in vitro and the cultured cells had the same characteristics of dental follicle cells of normal rat.

Animals↗
PubMed2004

[A quantitative study of anterior chamber angle with ultrasound biomicroscopy after cataract surgery with phacoemulsification and foldable intraocular lenses implantation].

OBJECTIVE: To study the changes in anterior chamber angle after phacoemulsification and foldable IOL implantation with ultrasound biomicroscopy. METHODS: Small-incision phacoemulsification and foldable IOL implantation were performed in 50 eyes of 46 senior patients, and the changes of anterior chamber angle were determined quantitatively by using ultrasound biomicroscopy before and one month after the surgery. RESULTS: In all patients, the angle was widened significantly one month after surgery (P < 0.01). The measurements of TIA500 (trabecular-iris angle at 500 micro m from the scleral spur), AOD250 (angle-opening distance at 250 micro m from the scleral spur) and AOD500 (angle-opening distance at 500 micro m from the scleral spur) increased significantly after the operation (P < 0.01). The mean post/pre-operative TIA500 ratio, AOD250 ratio and AOD500 ratio were 1.65 (1.12 - 4.91), 1.81 (1.06 - 2.67) and 1.65 (1.01 - 2.76), respectively. A significant negative correlation existed between preoperative and postoperative data. CONCLUSION: Small-incision cataract surgery deepens the anterior chamber and widens anterior chamber angle significantly in senior patients. The narrower the preoperative angle, the higher ratio of post/preoperative ratio found.

Aged↗
PubMed2004

[Molecular mechanisms of antioxidant effects of propylene glycol mannate sulfate].

AIM: To investigate the antioxidant mechanisms of propylene glycol mannate sulfate (PGMS) in hyperlipidemic rats. METHODS: Male Wistar rats were given high lipid emulsion diet to establish hyperlipidemic model. PGMS was given every day at different doses (37.8 and 75.6 mg.kg-1, ig) to hyperlipidemic rats for three weeks. In addition, diethyldithiocarbamate (DDC) was given 200 mg.kg-1.3 d-1 (i.p.) to inhibit SOD activity. Then, the MDA content was examined using TBA method to show the oxidation level, and the activities of SOD, GSH-Px and CAT were examined following the kit protocols to indicate the capability of eliminating OFR. RT-PCR was applied to study the expression of Cu, Zn-SOD mRNA in rat liver. RESULTS: The MDA content of PGMS treatment groups decreased markedly compared with hyperlipidemic group, and the activities of SOD, GSH-Px and CAT increased distinctly. Cu, Zn-SOD mRNA expression was significantly increased by PGMS treatment. Furthermore, the application of DDC(the SOD inhibitor) reduced total SOD activity and Cu, Zn-SOD mRNA expression induced by PGMS, and the content of MDA increased correspondingly. CONCLUSION: PGMS can induce the activities of antioxidant enzymes and the mRNA expression of Cu, Zn-SOD, which contribute to the elimination of oxygen free radical. This may explain the molecular mechanism of antioxidant effects of PGMS.

Animals↗
PubMed2004

[In vitro cytotoxicity evaluation of comfort denture adhesive].

OBJECTIVE: The purpose of this study was to evaluate the in vitro cytotoxicity of novel Comfort denture adhesive (Comfort-DA), which was developed by the authors, to human oral fibroblasts (HOFs). METHODS: A sample of Comfort-DA was prepared and extracted in culturing medium to prepare the eluate. Then the eluate was diluted by culturing medium to 50% and 75% concentration for the assessment of cytotoxicity by tetrazolium bromide (MTT) colorimetric assay. Wells containing fresh medium alone were served as control. Cell viability was recorded by optical density after culturing in an atmosphere of 5% CO2 and 95% air at 37 degrees C for 2, 3 and 4 days, respectively. The viability of HOF cells was evaluated by MTT assay to investigate cell proliferation. Optical density (OD) was measured by a spectrophotometer at 490 nm. Then evaluating the cytotoxicity grade in test groups according to the means of cell proliferation. ANOVA was used to test the statistical significance. RESULTS: The statistical analysis of the results of MTT cytological assay indicated significant difference (P < 0.05) in OD (indicate cell viability) between all concentrations of Comfort-DA and the control at all incubation times. The results of cell proliferation percentage also showed that the cytotoxicity grade of tested material only displayed "0-2". CONCLUSION: The generally favorable in vitro cytotoxicity of the Comfort-DA formulations indicates that this product may be an efficacious denture adhesive.

Adhesives↗
PubMed2004

[CD86 expression on alveolar macrophages and effects of anti-CD86 monoclonal antibody on the production of inflammatory cytokines in dust-mite allergic asthma patients].

OBJECTIVE: To investigate the CD(86) molecule expression on alveolar macrophages (AMs) before and after AM activation with dust-mite allergen and effects of anti-CD(86) monoclonal antibody on the production of inflammatory cytokines produced by cultured CD(34)(+) T cells, and to explore the pathogenesis of anti-CD(86) monoclonal antibody on inhibiting asthmatic inflammation. METHODS: AMs and CD(34)(+) T cells were isolated from bronchoalveolar lavage fluid (BALF) and from peripheral blood derived from 10 asthma patients allergic to house dust-mite dermatophagoides pteronyssinus. AMs were stimulated and activated by house dust-mite allergen and co-cultured with CD(34)(+) T cells. The co-cultured cells were divided into anti-CD(86) monoclonal antibody intervention group and CD(86) expression group with which the control groups were set up. The anti-CD(86) antibody was added to 0.1 mg/L and 1.0 mg/L in the experiment group and no antibody was added in the control group. The supernatants were harvested after 72 hour co-culture. The concentration of interferon-gamma (INF-gamma), interleukin-4 (IL-4) and IL-5 were determined by enzyme linked immunosorbent assay (ELISA). CD(86) expression group was divided into experiment and control groups, and house dust-mite allergen was added to the experiment group but no allergen was added in the control group. The cells of the two groups were harvested after 24 hour co-culture. The CD(86) molecule expression on the AMs was detected by flow cytometry. RESULTS: After activated by house dust-mite allergen, the average fluorescence density of CD(86) on AM in the experiment group [(50 +/- 9)%] was significantly higher than that in the control group [(23 +/- 5)%, P < 0.01]. The production of IL-4 and IL-5 was (135 +/- 19) ng/L, and (104 +/- 21) ng/L in the low-dose group respectively; (90 +/- 17) ng/L and (68 +/- 14) ng/L in the high-dose group; (187 +/- 24) ng/L and (161 +/- 23) ng/L in the control group; the differences among groups were significant (P < 0.01). The production of IFN-gamma was (193 +/- 39) ng/L in the low-dose group and (201 +/- 47) ng/L in the high-dose group respectively, and there was no significant difference between the two groups (P > 0.05). CONCLUSION: AMs may effectively present allergen to T cells in allergic asthma patients. Anti-CD(86) monoclonal antibody can inhibit the production of IL-4 and IL-5 by blocking the co-stimulatory signal of CD(34)(+) T cells. These data suggest that anti-CD(86) monoclonal antibody may hold therapeutic potentials in asthma by inhibiting airway inflammation.

Antibodies, Monoclonal↗
PubMed2004

[The efficacy and safety of 30 mg slow-released-gliclazide in type 2 diabetes mellitus].

OBJECTIVE: To evaluate the efficacy and safety profile of a slow-released-gliclazide (Diamicron MR) in type 2 diabetes patients. METHODS: 159 patients with type 2 diabetes were parallelly assigned to a slow-released-gliclazide or gliclazide group in a randomized, open, multi-center phase III study to compare the efficacy of slow-released-gliclazide and gliclazide on overall diabetes control through HbA1c and the adverse events including hypoglycemic episodes and change of vital signs, electrocardiogram and clinical laboratory parameters after a 12-week treatment period. RESULTS: No statistically significant difference was found in HbA1c levels between the slow-released-gliclazide and the gliclazide group (P = 0.66) after 12 weeks of treatment. HbA1c levels in the slow-released-gliclazide group were extremely close to those in the gliclazide group after 12 weeks of treatment (95% CI -0.15; +0.24%). Furthermore, plasma glucose area under curve/24 hours, mean daily plasma glucose and fasting serum insulin levels between these two groups were also not statistically different, indicating that the efficacy of treatment was similar. The number of patients reported to experience at least one episode of hypoglycemia, which was confirmed by capillary or venous glucose assessment, but by no means severe, was similar in both the treatment groups. The main reason for the hypoglycemic episodes was related to good plasma glucose control. No adverse event led to withdrawal of the medication. Systolic and diastolic blood pressure, heart rate and body weight did not change during the study. There was also no noticeable change in electrocardiogram, lipid profile, and parameters in blood biochemistry and hematologic testing during the study. CONCLUSION: Slow-released-gliclazide and gliclazide had a similar efficacy and safety profile.

Adult↗
PubMed2004

[Clinical outcomes of women with transfusion-associated hepatitis C after 10-15 years follow-up].

BACKGROUND: To investigate natural history of hepatitis C virus (HCV) infection and related factors in China. METHODS: Totally 41 women infected with HCV 10-15 years ago were evaluated in this study. Their clinical manifestations were recorded and sera tested for alamine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (gamma-GT), alkaline phosphatase (ALP), total bilirubin (TBIL), direct bilirubin (DBIL), total protein (TP), albumin (ALB), and alpha-fetoprotein (alpha-FP), as well as virus markers. The B-type ultrasound examination was performed on the liver, gall bladder, spleen and pancreas. For virus markers, HCV RNA was detected with fluorogenic-quantitative polymerase-chain-reaction, HBsAg and anti-HCV antibody, with enzyme-linked immunosorbent assay (ELISA). RESULTS: Ten to 15 years after infection, the infection was cleared spontaneously in 8 cases (19.51%); 73%(30/41) cases had signs at present, 32% (13/41) cases had mild ALT and/or AST elevation. On ultrasound examination, 83%(34/41) had mild degree 17%(7/41) moderate degree changes of the viral hepatitis. CONCLUSION: Women with HCV infection for 13 +/- 1 (10-15) years after transfusion had slight hepatic inflammation. A part of them had cleared the virus spontaneously.

Adult↗
PubMed2004

[Clinical outcomes of 283 patients of transfusion-related hepatitis C in the northern areas of China].

OBJECTIVE: To investigate the natural history and clinical outcomes in a cohort of transfusion-related hepatitis C in northern areas of China. Methods The authors studied 283 patients (137 males, 146 females, mean age 45.79+/-9.92 age) who became infected with HCV while donating plasma 12.25 years ago. These cases were subjected to ultrasonography and liver biochemical tests and serologic anti-HCV assays. Statistical analyses were performed using the SPSS software. RESULTS: Ultrasonographic findings suggestive of liver cirrhosis were 8.3% of cases. No decompensated cirrhosis or HCC was detected. The value of ALT was higher in severe chronic hepatitis (mean 62.07+/-50.87 IU/L) and cirrhosis (mean 115.50+/-108.41 IU/L) patients than in the other groups (mean 32.30+/-29.10 IU/L). The abnormal rate of ALT was 53.3% in severe group, 100% in cirrhosis group. CONCLUSION: The natural history of transfusion-related hepatitis C in the areas seemed to be relatively mild when compared with previous data. Our cases showed relatively low rate of positive findings in ultrasonography. None of this cohort had the decompensated cirrhosis or HCC. The factor of sex but not the age at time of infection was found being related to the outcomes. In the absence of liver biopsy, ultrasonography was a suitable and sensitive method for the diagnosis of the progressive hepatitis and cirrhosis.

Adult↗
PubMed2004

[Study on the chemical constituent from Buddleja purdomii].

OBJECTIVE: To study the chemical constituents from Buddleja purdomii W. W. Smith. METHODS: The constituents were isolated and purified by various chromatographic methods and structurally identified by spectral analysis. RESULTS: 4 compounds were identified as vanillin (I), vanillic acid (II), acteoside (III), acteoside isomer (IV). CONCLUSION: All these compounds were obtained from this plant for the first time.

Benzaldehydes↗
PubMed2004

[Management of intracanal separated instruments with the microsonic technique and its clinical outcome].

OBJECTIVE: To evaluate the clinical effect of microsonic technique on removal of intracanal separated instruments. METHODS: Forty-four teeth with 47 intracanal separated instruments, which could not be successfully managed by conventional methods, were endodontically treated with ultrasonic instruments under dental operating microscope. The success rate was calculated and the cases were reviewed 5 to 19 months after retreatment. RESULTS: Thirty-four (34/47) separated instruments in 33 (33/44) teeth were completely removed with a success rate of 75%. Thirteen separated instruments in 11 teeth, however, could not be eliminated from the canals. Root canal perforation or vertical fracture was not found. None of these teeth showed periapical deterioration in the follow-up. CONCLUSIONS: The combined use of dental operating microscope and ultrasonic instruments in endodontic treatment enriched the way of managing complicated cases of intracanal separated instruments.

Adult↗
PubMed2004

[Enamelin transcriptional expression in developing postnatal rat tooth germ].

OBJECTIVE: To observe the transcriptional expression of enamelin in developing postnatal rat first mandibular molar germs, for further studies of functions of enamelin in enamel development and mineralization. METHODS: Tissue slices of first mandibular molar germ of rat 1, 3, 7, 10, 14 days after birth were prepared. The enamelin mRNA expression was identified by in situ hybridization. RESULTS: Enamelin mRNA was observed in both ameloblast and odontoblast in 1-10 day old rat postnatal first mandibular molar germs. Enamelin mRNA appeared very weakly at 1st day, and increased through 3rd day, reached the maximum at 7th day, and reduced at 10th day and became negative at 14th day postnatally; while the expression of enamelin mRNA in odontoblast maintained lower from 1st to 10th day and negative at 14th day postnatally. CONCLUSION: Enamelin gene transcriptional expression lasts from preameloblast to maturation ameloblast, which suggests that enamelin may participate in the development of enamel and mantle dentin.

Ameloblasts↗
PubMed2004

Effects of timely insulin treatment on protection of beta cells in a rat model of type 2 diabetes mellitus.

BACKGROUND: Insulin treatment plays a key role in management of diabetes mellitus. Clinical researches showed that extra improvements in restoration of insulin secretion of pancreatic beta cells were found in patients with newly diagnosed type 2 diabetes. The purpose of this study was to investigate the effects of early insulin treatment on insulin mRNA expression and morphological alterations of beta cells in a Sprague Dawley (SD) rat model of type 2 diabetes. METHODS: A rat model of type 2 diabetes mellitus (T2DM) was induced by a high fat diet (high energy, HE) and low doses of streptozotoxin (STZ, 40 mg/kg). A group of diabetic rats was then injected with protamine zinc insulin [PZI, 1 - 2 U x kg(-1) x d(-1)] for one week. Insulin mRNA expression, morphological features of pancreatic islets, and metabolic parameters were examined in rats using reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and other techniques. RESULTS: In insulin-treated diabetic rats, insulin mRNA levels prominently increased by 81.3% (P < 0.05), as compared with untreated diabetic rats. Moreover, timely insulin treatment noticeably improved the insulin content of beta cells, with an increase of 10.2% (P < 0.05), despite a slight reduction in fasting blood glucose (FBG), triglyceride (TG), and free fatty acid (FFA) levels, as compared to an untreated diabetic group. CONCLUSION: Insulin treatment at the onset of T2DM effectively improves insulin synthesis, as confirmed by morphological changes to beta cells in a rat model of type 2 diabetes.

Adipose Tissue↗
PubMed2004

[Epitope mapping of myeloperoxidase antibodies in propylthiouracil-induced vasculitis and microscopic polyangiitis].

OBJECTIVE: To compare the epitopes of antibodies for myeloperoxidase (MPO) in the serum from patients with propylthiouracil (PTU) induced vasculitis and microscopic polyangiitis (MPA). METHODS: Serum samples from patients with PTU-induced vasculitis (n = 10) and MPA (n = 10) were collected and used to inhibit monoclonal antibodies against human MPO 3D8 and 6B9 and then affinity was purified, horseradish peroxidase conjugated and human MPO antibodies determined (Pab1-HRP, Pab2-HRP) in a competitive inhibition ELISA system using soluble human MPO as solid phase ligands. The Pab1-HRP and Pab2-HRP were affinity purified from plasma exchanges of a patient with PTU-induced vasculitis and a patient with MPA. The inhibition rates were evaluated and compared between PTU group and primary MPA group. RESULTS: In PTU group, all the 10 serum samples could inhibit 3D8; the average inhibition rate was 44.7%, 9/10 of the serum samples could inhibit 6B9; the average inhibition rate was 35.6%; In MPA group, all 10 serum samples could inhibit 3D8 and 6B9; the average inhibition rates were 68.4% and 62.2%. Serum in both groups could inhibit Pab1-HRP and the inhibition rates were both more than 80%; the average inhibition rate for Pab2-HRP in MPA group was significantly higher than that in PTU group (76.3% vs 58.9%, P < 0.01). CONCLUSIONS: MPO antibodies from patients with PTU-induced vasculitis and patients with primary MPA could recognize more than one epitopes on native MPO molecule. Although the epitopes were overlapping between the two groups, the epitopes of MPO antibodies from patients with PTU-induced vasculitis might be more restricted.

Adolescent↗
PubMed2004

[Diagnosis and management of uterine arteriovenous fistula with massive vaginal bleeding].

OBJECTIVE: To study the clinical manifestation, diagnosis, management and prognosis of uterine arteriovenous fistula with massive vaginal bleeding. METHOD: The clinical records of 15 patients who satisfied the diagnostic criteria were retrospectively analyzed. RESULTS: All patients had massive vaginal bleeding, with a history of caesarean section, curettage or gynecologic carcinoma. The disease could be diagnosed by angiography or color Doppler ultrasound. Vaginal bleeding was aggravated by dilation and curettage. Fourteen patients were treated with uterine artery embolization, and no complications occurred postembolization. Of the eleven successful embolizations, all patients returned normal menstrual cycling. Five of these patients became pregnant later. CONCLUSIONS: Uterine arteriovenous fistula is a rare and potentially life threatening disease. Uterine artery embolization is a safe and effective treatment for this disease, and it can preserve normal function of uterus and ovaries.

Adult↗