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1.
Article in Chinese | WPRIM | ID: wpr-912125

ABSTRACT

Objective:To identify new host substrate of SseK3 and study its biological function.Methods:A yeast two hybrid system (Y2H) was used to identify the potential binding proteins of SseK3 from the Hela cDNA library; the arginine N-acetylglucosamine (Arg-GlcNAc) modification of the substrate protein by SseK3 was detected by co-expression in 293T cells and in vitro activity test; the modification sites of the substrate protein by SseK3 were detected by point mutation; the effect of Arg-GlcNAc modification of the substrate protein on its interaction protein binding ability was detected by immunoprecipitation test. Results:Results of Y2H and gene sequencing showed that Snapin was a new substrate of SseK3. Snapin could be Arg-GlcNAc-modified by SseK3 in vivo and in vitro; the modification sites of Snapin were arginine 119 and arginine 120; Arg-GlcNAc-modified Snapin inhibited its binding with SNAP25. Conclusions:Snapin, a new host substrate protein of SseK3, was successfully screened in this study. The Arg-GlcNAc modification of Snapin by SseK3 was studied, and the effect of this modification on Snapin function was preliminarily studied, which provided theoretical basis for further understanding the function of Arg-GlcNAc modification of bacteria and the mechanism of action in the process of pathogen infection.

2.
Article in Chinese | WPRIM | ID: wpr-885642

ABSTRACT

Objective:To analyze the effects of espO gene knockout on the biological characteristics of enterhemorrhagic Escherichia coli (EHEC). Methods:Two-step methods mediated by the suicide plasmid pCVD442-Δ espO and plasmid pTrc99a were used to construct the espO gene-deleted strain (Δ espO) and the complemented mutant (CΔ espO), respectively. HeLa cells were infected with different EHEC strains to analyze the biological functions and lethal effects of espO gene during infection. Results:PCR, electrophoresis and gene sequencing showed that the Δ espO and CΔ espO mutants were successfully constructed. Compared with the wild-type strain, neither the Δ espO nor CΔ espO mutant showed significant difference in growth rate, indicating that the espO gene had no influence on the growth and replication of EHEC. Furthermore, EspO could activate the tumor necrosis factor receptor (TNF)-induced NF-κB signaling pathway, while the effector protein NleB could inhibit the process. EspO could not inhibit the death of HeLa cells induced by TNF or TNF-related apoptosis-inducing ligand (TRAIL) after EHEC infection. Conclusions:In this study, we successfully constructed the espO gene-deleted and complemented mutants of EHEC and preliminarily analyzed the interaction between espO gene and host cells and the effects of espO gene on cell apoptosis during infection, which provided reference for further research on the in vitro biochemical activity and in vivo pathogenic roles of EspO.

3.
Chinese Journal of Biotechnology ; (12): 1021-1030, 2020.
Article in Chinese | WPRIM | ID: wpr-826874

ABSTRACT

Pectin methylesterase (PME) is an important pectinase that hydrolyzes methyl esters in pectin to release methanol and reduce the degree of methylation of pectin. At present, it has broad application prospects in food processing, tea beverage, paper making and other production processes. With the in-depth study of PME, the crystal structures with different sources have been reported. Analysis of these resolved crystal structures reveals that PME belongs to the right-hand parallel β-helix structure, and its catalytic residues are two aspartic acids and a glutamine, which play the role of general acid-base, nucleophile and stable intermediate, in the catalytic process. At the same time, the substrate specificity is analyzed to understand the recognition mechanism of the substrate and active sites. This paper systematically reviews these related aspects.


Subject(s)
Carboxylic Ester Hydrolases , Chemistry , Metabolism , Catalytic Domain , Crystallography , Pectins , Metabolism , Protein Structure, Tertiary , Substrate Specificity
4.
Chinese Pharmacological Bulletin ; (12): 1226-1231, 2019.
Article in Chinese | WPRIM | ID: wpr-857146

ABSTRACT

Aim To study the expression pattern of neuroblastoma, suppression of tumorigenicity 1 (NBL1) in pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). Methods Forty rats were randomly allocated into control group (n = 10) and MCT group (n= 30). Intraperitoneal injection of 60mg 'kg"1 MCT for MCT group or equal volume normal saline for control group was performed. The changes of NBL1 in lungs and plasma of the 3 rd, 4 th and 5 th week after MCT injection were detected respectively. NBL1 levels in rat plasma were detected by enzyme linked immunosorbent assay. Results At the 3 rd, 4 th, and 5 th week after MCT injection, the mRNA level of NBL1 decreased by 70%, 81% and 89% , the protein level decreased by 36% , 78% and 99% , and the plasma concentration of NBL1 decreased from (2. 82 ± 0. 58) xg L"1 (control rats) to (1. 90±0.55) fig L-1, (1.51 ±0.43) jxg L'1, (0.64 ±0. 34)ug L-l and presented a negative correlation with pulmonary hemodynamic indices and right ventricular hypertrophy. Immunohistochernical staining demonstrated that NBL1 was mainly expressed in small pulmonary arteries in normal lungs from control group but seldom detected in severely remodeled pulmonary arteries from MCT group. Furthermore, NBL1 significantly inhibited the activation of BMP signal in pulmonary artery endothelial cells induced by BMP2/4. Conclusions NBL1 level demonstrates a stepwise decrease in MCT induced PAH, implying its vital roles in the pulmonary vascular remodeling process and the possibility of NBL1 to be a potential biomarker for PAH.

5.
Acta Pharmaceutica Sinica ; (12): 396-402, 2018.
Article in Chinese | WPRIM | ID: wpr-779888

ABSTRACT

Tonkinensis is commonly used in the treatment of hepatitis B infection in China with its effect­tiveness in reducing clinical symptoms and improving liver function. However, the mechanism of the anti-HBV (hepatitis B virus) effect of Tonkinensis is still not clear. In this study, an integrative analysis using the network pharmacology and metabolomics was employed in identification of the main targets and mechanisms of Tonkinensis in treatment of HBV infections. First, the "drug-target" network was established by predicting the targets of the main chemical components of Tonkinensis; Secondly, the differential metabolites associated with the anti-HBV effect of Tonkinensis were analyzed with the LC-MS based metabolomics in HepG2.2.15 cells; Finally, the "drug ingredients-targets-metabolites" network was constructed to screen the main anti-HBV targets of Tonkinensis. The results suggest that Tonkinensis may act on 16 target proteins in the network of retinol metabolism, peroxisome proliferator activate-receptors (PPAR) signaling pathway and transcriptional regulation of cancer and so on, which contributed to the control of HBV replication and the regulation of immune function and metabolic disorders.

6.
Acta Pharmaceutica Sinica ; (12): 1063-1068, 2017.
Article in Chinese | WPRIM | ID: wpr-779695

ABSTRACT

By using the drug metabolizing enzyme inhibitors, the effects of metabolic factors on potential liver injury induced by the main component, trans-2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside(trans-SG), in Polygonum multiflorum was investigated. The main metabolic enzyme isoforms involved in trans-SG metabolism were also screened. The results showed that trans-SG at the dosage 31 mg·kg-1 did not cause liver injury; and the combination of trans-SG with the phase I metabolic enzyme inhibitor, 1-benzylimidazole (10 mg·kg-1), did not change the degree of liver injury(compared with LPS + trans-SG group, P > 0.05). However, the combination of trans-SG with phase II metabolic enzyme inhibitor, ketoconazole(35 mg·kg-1), significantly increased the degree of liver injury(compared with LPS + trans-SG group, P < 0.05). The phase I metabolites of trans-SG were not detected in human liver microsomes phase I metabolism system, while the phase II trans-SG metabolites were detected in recombinant human UGT isozymes phase II metabolism system. Six isoforms of uridine diphosphate glucuronate transferase(UGT)exhibited abilities to metabolize trans-SG and the order of metabolic ability was: UGT1A1 > UGT1A9 > UGT1A7 > UGT1A10 > UGT2B7 > UGT1A8. The results showed that trans-SG was mainly metabolized by UGT in phase II metabolism. The inhibition of drug metabolizing enzymes of phase II can increase the liver injury susceptibility of trans-SG, which provides a reference to the evaluation of susceptible factors and drug incompatibility research of Polygonum multiflorum.

7.
Acta Pharmaceutica Sinica ; (12): 1027-1032, 2017.
Article in Chinese | WPRIM | ID: wpr-779690

ABSTRACT

To investigate the effects of peroxisome proliferator-activated receptor gamma(PPAR-γ)on the liver injury of Polygonum multiflorum, we established a model of immunological idiosyncrasy liver injury induced by lipopolysaccharide. The 70 Sprague-Dawley(SD)rats were randomly divided into control group, LPS group(2.8 mg·kg-1), PM group(crude drug, 2.16 g·kg-1), PPAR-γ agonist group(pioglitazone, 0.5 mg·kg-1), PM+LPS group(crude drug 2.16 g·kg-1, 2.8 mg·kg-1), PPAR-γ agonist+LPS group(0.5 mg·kg-1, 2.8 mg·kg-1)and PM+LPS+PPAR-γ agonist group(crude drug, 2.16 g·kg-1, 2.8 mg·kg-1, 0.5 mg·kg-1). The rats were orally given PM, once a day for consecutive 2 days. The control rats were given the same amount of distilled water. Liver injury was induced by intravenous injection of LPS. Sodium pentobarbital was injected intraperitoneally for anesthesia, and liver samples were collected together with blood. The plasma levels of alanine transaminase(ALT), aspartate aminotransferase(AST), tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), interleukin-6(IL-6)and interferon-γ(IFN-γ)were measured. Pathological changes and hepatocellular apoptosis were examined by liver biopsy, and immunohistochemical observation of liver tissue expression of PPAR-γ and NF-κB p65. A negative correlation was observed between the expression of PPAR-γ in hepatic tissue and liver injury of Polygonum multiflorum. PPAR-γ agonist significantly reduced the PM-induced idiosyncratic liver injury in rats according to serum ALT and AST(P < 0.05), reduced liver pathological injury and hepatocyte apoptosis, decreased serum TNF-α and other inflammatory cytokines(P < 0.05), liver tissue PPAR-γ expression, and inhibited expression of NF-κB p65(P < 0.05). The results suggest that the occurrence of immunological idiosyncrasy liver injury of PM is related to inhibition of the PPAR-γ pathway and elevation of inflammatory factors. PPAR-γ agonist can reverse the idiosyncratic liver injury induced by PM, and provide a reference for elucidating mechanism of idiosyncratic liver injury induced by Polygonum multiflorum.

8.
Acta Pharmaceutica Sinica ; (12): 116-2016.
Article in Chinese | WPRIM | ID: wpr-779144

ABSTRACT

Decoction is one of the most commonly used dosage forms of traditional Chinese medicine. The stability of chemical constituents in decoction is closely related to the clinical efficacy and safety. There were few reports about the influence of metal ions in the stability of chemical constituents in traditional Chinese medicine. However, there is no evidence that metal ions in decoction water need to be controlled. In this study, 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), one of the main constituents in Polygoni Multiflori Radix was studied. Ordinary tap water, deionized water, and water containing different metal ions were used to investigate and compare the influence on THSG . The results showed that after storage in a dark place at the room temperature for 10 days, the degradation of THSG was 7% in deionized water, while undetectable in tap water. The content of THSG could be decreased by different kinds of metal ions, and the effect was concentration- dependent. Moreover, Fe3+ and Fe2+ showed the greatest influence at the same concentration; and our study has shown that THSG decreased more than 98% in Fe3+ and Fe2+ solutions at 500 ppm concentration. In the same time we found out p-hydroxybenzaldehyde (molecular weight: 122.036 7) and 2,3,5-trihydroxybenzaldehyde-2- O-glycoside (molecular weight: 316.079 4) were the main degradation products of THSG in tap water and water containing Cu2+, Ca2+, Zn2+, Mg2+ and Al3+. The product of THSG dimer with a water molecule was found in water containing Fe3+ and Fe2+. The above results showed that the metal ions in water could significantly influence the stability of THSG in water, indicating that the clinical efficacy and safety of decoction would be affected if the metal ions in water were not under control. It's suggested that deionized water should be used in the preparation of decoction containing Polygoni Multiflori Radix in the clinic to avoid degradation of THSG. Meanwhile, decoction prepared by tap water should be taken by patients in a short time. Our investigation provides important information and reference about the influence of metal ions on the stability of decoctions in other traditional Chinese medicine that have unstable groups such as hydroxyls and unsaturated bonds, etc.

9.
Article in Chinese | WPRIM | ID: wpr-320862

ABSTRACT

To investigate the protective effects of oxymatrine (OMT) against H2O2-induced damage in L02 cells and research the mechanism,L02 cells were used as the research object. The oxidative stress model of L02 was established by hydrogen peroxide (H2O2). CCK-8 was used to detect the cell activation of L02 cells treated by different OMT. FCM (flow cytometry) assay was used to evaluate the cell proliferation of L02 cells treated by OMT. The apoptosis of L02 cells was detected using Annexin-V/7-AAD apoptosis detection kit. The level of ROS was detected by DCFH-DA fluorescence probe. The GSH-PX and SOD were detected by micro plate and colorimetric method. Results showed that when the concentration of OMT is between 6.25 and 100 mg•L⁻¹, it could promote the production of NADPH and strengthen the activity of GSH-PX and SOD to get rid of the ROS to protect the L02 cell from the apoptosis of L02 cell induced by H2O2.

10.
Article in Chinese | WPRIM | ID: wpr-307108

ABSTRACT

The protective action and the relevant mechanism of Liuwei Wuling tablet on acute alcoholic hepatic injury in mice were investigated. All the C57BL/6 mice were divided randomly into 7 groups including blank, model, bifendate (150 mg•kg⁻¹, positive control) and experimental groups consisted of extremely low dose (0.1 g•kg⁻¹), low (0.5 g•kg⁻¹), upper (4 g•kg⁻¹) and high dose (8 g•kg⁻¹) of Liuwei Wuling tablet groups. The acute liver injury model was induced by modified method that the model, positive control and experimental groups were orally administrated 56% alcohol (6 g•kg⁻¹) twice at 12 hour intervals on the fifth day after drugs administration. After 12 hours, the mice were sacrificed to contribute blood and liver for biochemical and histological examinations. Compared with the model, the activities of ALT and AST in serum decreased significantly in different Liuwei Wuling tablet groups. Meanwhile, in liver tissue, the levels of TG, MDA, TNF-α and IL-1β reduced obviously while the GSH and SOD activities showed markedly increase with a dose-dependent manner. Correspondingly, the microscopically pathological differences of the liver tissue observed by HE and oil red O staining indicated that the liver cell swelling, hydropic degeneration and lipid droplets formation induced by alcohol were significantly improved, which suggested the Liuwei Wuling tablet can reduce the liver injure. In conclusion, the Liuwei Wuling tablet had the protective effect on acute alcoholic hepatic injury which maybe depended on the mechanism of relieving lipid peroxidation, elevating antioxidant enzymes activity, inhibiting oxidative stress and reducing inflammation factors expression.

11.
Acta Pharmaceutica Sinica ; (12): 116-121, 2016.
Article in Chinese | WPRIM | ID: wpr-320007

ABSTRACT

Decoction is one of the most commonly used dosage forms of traditional Chinese medicine. The stability of chemical constituents in decoction is closely related to the clinical efficacy and safety. There were few reports about the influence of metal ions in the stability of chemical constituents in traditional Chinese medicine. However, there is no evidence that metal ions in decoction water need to be controlled. In this study, 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), one of the main constituents in Polygoni Multiflori Radix was studied. Ordinary tap water, deionized water, and water containing different metal ions were used to investigate and compare the influence on THSG. The results showed that after storage in a dark place at the room temperature for 10 days, the degradation of THSG was 7% in deionized water, while undetectable in tap water. The content of THSG could be decreased by different kinds of metal ions, and the effect was concentration-dependent. Moreover, Fe3+ and Fe2+ showed the greatest influence at the same concentration; and our study has shown that THSG decreased more than 98% in Fe and Fe2+ solutions at 500 ppm concentration. In the same time we found out p-hydroxybenzaldehyde (molecular weight: 122.036 7) and 2,3,5-trihydroxybenzaldehyde-2-O-glycoside (molecular weight: 316.079 4) were the main degradation products of THSG in tap water and water containing Cu2+, Ca2+, Zn2+, Mg2+ and Al3+. The product of THSG dimer with a water molecule was found in water containing Fe3+ and Fe2+. The above results showed that the metal ions in water could significantly influence the stability of THSG in water, indicating that the clinical efficacy and safety of decoction would be affected if the metal ions in water were not under control. It's suggested that deionized water should be used in the preparation of decoction containing Polygoni Multiflori Radix in the clinic to avoid degradation of THSG. Meanwhile, decoction prepared by tap water should be taken by patients in a short time. Our investigation provides important information and reference about the influence of metal ions on the stability of decoctions in other traditional Chinese medicine that have unstable groups such as hydroxyls and unsaturated bonds, etc.


Subject(s)
Drugs, Chinese Herbal , Chemistry , Glucosides , Chemistry , Ions , Chemistry , Metals , Chemistry , Plant Roots , Chemistry , Polygonaceae , Chemistry , Stilbenes , Chemistry
12.
Article in Chinese | WPRIM | ID: wpr-272706

ABSTRACT

This paper was aimed to investigate the protective effects of luteolin (Lut) against acetaminophen(APAP)-induced damage in L02 liver cells. CCK-8 was used to detect the cell activation of L02 cells treated by different Lut. The concentration and time of APAP induced L02 cell damage was screened. The effect of Lut on APAP induced apoptosis of L02 cells was detected by cell morphological observation, CCK-8 assay and flow cytometry. The contents of MDA, GSH and SOD activity in cell supernatant were detected by colorimetric assay. The expression of apoptosis-related genes Bax, Bcl-2 and caspase-3 was detected by RT-PCR. The results showed that Lut in 2.5-40 μmol•L⁻¹ range does not affect the activity of L02 cells; 12 mmol•L⁻¹ APAP incubated with L02 cell 12 h to establish damage model. Compared with the model group, the cell status of Lut group was significantly improved, the cell body was increased, the adherence ability was recovered, and the apoptosis rate was obviously decreased. MDA content decreased significantly (P<0.05, P<0.01), GSH and SOD activity significantly increased (P<0.05, P<0.01), at the same time, it could up-regulate expression of Bcl-2 mRNA and down-regulate the expression of Bax and caspase-3 mRNA. In conclusion,Lut has protective effect on APAP induced L02 cell injury, and its mechanism may be related to the reduction of oxidative stress and inhibition of apoptosis.

13.
Article in Chinese | WPRIM | ID: wpr-286338

ABSTRACT

<p><b>OBJECTIVE</b>To observe clinical characteristics of herb-induced liver injury (HILI).</p><p><b>METHODS</b>General conditions, medical history, clinical manifestations, biochemical indices, prognosis, and Roussed Uclaf Causality Assessment Method (RUCAM) scores were retrospectively analyzed in 595 inpatients at 302 Military Hospital between January 2009 and January 2014.</p><p><b>RESULTS</b>There were 423 cases (accounting for 71.1%) were females with multiple onset age ranging 41 to 50 years old. The median time from starting Chinese herbs to the occurrence of liver injury (LI) was 30 days (15-75 days), and 511 cases (85.9%) were classified as hepatocellular injury. Chinese herbs inducing HILI were mainly used for skin disease (102 cases, 17.1%), osteoarticular disease (57 cases, 9.6%), and gastrointestinal disease (49 cases, 8.2%), covering 207 kinds of Chinese patent medicines. Polygonum multiflorum, Psoralea corylifolia, and Corydalis ambigua were often seen in Chinese prescriptions. In RUCAM scoring, 451 HILI patients (accounting for 74.1%) were very possibly associated with Chinese herbs. Liver failure occurred in 47 HILI patients (accounting for 7.9%), cirrhosis in 45 patients (accounting for 7.6%), chronic HILI in 80 patients (accounting for 13.4%), 27 (4.5%) died, and only 2 (0.3%) underwent liver transplantation.</p><p><b>CONCLUSIONS</b>Chinese herbs could cause LI or even death. Attention should be paid to herbal hepatotoxicity and improving monitoring system of HILI.</p>


Subject(s)
Chemical and Drug Induced Liver Injury , Diagnosis , Female , Humans , Prognosis , Retrospective Studies
14.
Article in English | WPRIM | ID: wpr-270561

ABSTRACT

<p><b>OBJECTIVE</b>The purpose of this study was to explore an objective measure to assess actual body shape of children and adolescents in China.</p><p><b>METHODS</b>Based on the Chinese National Survey on Student's Constitution and Health (CNSSCH) in 2005, 210 927 children and adolescents' (7-18 years) body height, body weight, chest circumference, sitting height, chest circumference-height ratio, chest circumference-sitting height ratio, chest circumference-low limb ratio, and sitting height-low limb ratio measurements were used to develop an objective measure by using transformation variables and explored factor analysis (EFA). Discrimination power of the objective measure was evaluated based on BMI reference and Receiver Operating Characteristic curves (ROC).</p><p><b>RESULTS</b>The objective measure included four dimensions scores: transverse dimension (TD) indicating weight and chest circumference; length dimension (LD) indicating height and sitting height; transverse-length ratio dimension (TLD) indicating chest circumference-height ratio, chest circumference-sitting height and chest circumference-low limb ratio; proportion dimension (PD) indicating sitting height-low limb ratio. The whole dimension (WD) indicating the whole body shape was showed by the average of four dimensions scores. Four dimensions and WD scores were approximately 80 in children and adolescents with normal weight, and higher than those of overweight, obesity, and underweight (all P-values <0.001). Areas under ROC of overweight and obesity compared with normal weight ranged from 0.88 to 1.00 for scores of TD, TLD, and WD.</p><p><b>CONCLUSION</b>The objective measure which included four dimensions was explored, and TD, TLD, and WD had significant discrimination power.</p>


Subject(s)
Asian Continental Ancestry Group , Body Height , Body Mass Index , Body Size , Body Weight , Child , China , Female , Humans , Male
15.
Article in Chinese | WPRIM | ID: wpr-242989

ABSTRACT

<p><b>OBJECTIVE</b>The aim of this study was to determine the metameric color differences between natural teeth and three brands of commercially available resin teeth.</p><p><b>METHODS</b>The spectral reflectance and color coordinates of natural teeth and three brands of commercially available resin teeth of A2 shade were measured with a spectrophotometer (PR-650) according to the CIE L*, a*, b* and CIE XYZ color scale relative to illuminant D65, A, cool white fluorescent (CWF) and ultraviolet (UV), and the metameric indices were calculated to determine the metameric color differences between natural teeth and resin teeth.</p><p><b>RESULTS</b>CIE L*, a*, b* values were influenced by the type of illuminants in both natural teeth and resin teeth. The pattern of spectral reflectance curves for natural teeth and resin teeth of A2 shade were different, while there were more than three crossing points among each curves, which meant the color of natural teeth and resin teeth of A2 shade might be the same under certain illuminant. The metameric indices between natural teeth and resin teeth of A2 shade were 3.48, 2.52 and 3.36 under illuminant A; 1.21, 1.90, and 2.79 under illuminant CWF; 1.59, 2.07, and 4.07 under illuminant UV. The metameric indices between resin teeth of different brand were 1.08, 0.10, and 1.01 under illuminant A; 1.46, 2.23, and 0.94 under illuminant CWF; and 2.55, 2.69, and 4.64 under UV.</p><p><b>CONCLUSION</b>Changes in optical properties of resin teeth of A2 shade relative to the different illuminants were different from those of natural teeth, the metameric effect between natural teeth and resin teeth of A2 shade were significant. Therefore, shade matching between natural teeth and resin teeth should be performed under more than one illuminant.</p>


Subject(s)
Color , Composite Resins , Humans , Lighting , Mouth, Edentulous , Resins, Synthetic , Spectrophotometry
16.
Article in Chinese | WPRIM | ID: wpr-242928

ABSTRACT

<p><b>OBJECTIVE</b>To investigate expansion characteristics of two kinds of commercial investment (Cristo balite Micro II and Cristo Quick), and their effects on cast accuracy of a dental Ag-Pd casting alloy.</p><p><b>METHODS</b>Two kinds of investment were mixed at the ratio of 1:3. The setting and thermal expansion curves of the investment were recorded according to the requirements of ISO7490 and expansion rate calculated, respectively. Plate-like wax-patterns with pre-marked points were invested in casting rings (lined with ceramic fiber liners with thickness of 0.45 mm). Castwell M.C dental alloy were melted with gas flame and cast with a centrifugal casting machine. The differences between the castings and the wax patterns at corresponding points were calculated to represent the dimensional changes of the investment.</p><p><b>RESULTS</b>The setting, thermal and total expansion rates were 0.68, 1.18, 1.86 for Cristo balite Micro II, and 0.94, 1.03, 1.97 for Cristo Quick. The setting and thermal expansion rates were statistically significant between two kinds of investment (P < 0.05), while not for the total expansion rates (P > 0.05). Effect of different investment on the precision of castings was not statistically significant (P > 0.05).</p><p><b>CONCLUSION</b>Within the scope of this study, gypsum-bonded investment with similar total expansion rates but different expansion characteristics has no effect on the casting precision of Ag-Pd dental alloys.</p>


Subject(s)
Calcium Sulfate , Ceramics , Dental Alloys , Dental Casting Investment , Dental Casting Technique , Investments
17.
Article in Chinese | WPRIM | ID: wpr-296683

ABSTRACT

<p><b>OBJECTIVE</b>To study the effects of different heating timings after mixing the materials and different heating methods on the expansion characters of a quick-heating gypsum-bonded investment.</p><p><b>METHODS</b>The setting expansion rate of GC Cristoquick II gypsum-bonded investment was measured with a setting expansion tester 30, 60, 120 min after mixing the material respectively. The thermal expansion rates of the material at different setting time (30, 60, 120 min after mixing) and under different heating treatment methods (quick and conventional heating techniques) were also determined using a thermal dilatometer for dental investments, the total linear expansion rate were calculated. The effects of heating time and heating methods on the expansion of the investments were statistically analyzed with SPSS 11.0 software, using ANOVA multiple comparison (alpha=0.05).</p><p><b>RESULTS</b>Statistical differences were found among the setting and thermal expansion rates of the investment at different heating timings after mixing the material (P<0.01). Setting expansion, thermal expansion and total expansion rates increased with the setting time before heat treatment, while thermal expansion rates under different (quick and conventional) heating methods were not statistically significant (P>0.05).</p><p><b>CONCLUSION</b>The expansion characters of the quick-heating gypsum-bonded investment are influenced by different heating timings after mixing the material. The heat treatment technique of this quick-heating investment recommended needs to be modified to ensure casting precision.</p>


Subject(s)
Calcium Sulfate , Dental Casting Investment , Dental Casting Technique , Heating , Hot Temperature , Humans , Investments
18.
Chinese Journal of Biotechnology ; (12): 273-277, 2007.
Article in Chinese | WPRIM | ID: wpr-325380

ABSTRACT

Aspergillus fumigatus wild-type phytase has many favorable properties, such as a good thermorstability and a broad pH optimum. However, the specific activity of the enzyme is relative low. A. fumigatus Q23L phytase resulted in a remarkable increase in specific activity around pH4.5 - 7.0, but the pH stability of Q23L was lower than A. fumigatus wild-type phytase. To increase the pH stability of Q23L, the mutant Q23LG272E was constructed by site-directed mutagenesis with PCR. The gene of A. fumigatus wild-type phytase and the mutant genes encoding the Q23LG272E and the Q23L were correctly expressed in Pichia pastoris GS115. Enzymes were purified and their enzymatic properties were determined. The results revealed that the specific activity of the Q23L improved remarkably, which increased from 51 u/mg of the wild type to 109 u/mg at pH5.5. Meanwhile, the pH stability of Q23L, decreased evidently, especially from pH3.0 to pH4.0.The pH stability of Q23LG272E in pH3.0 - 4.5 and pH6.5 - 7.0 has been improved compared with Q23L. The specific activity of Q23LG272E basically maintained at the level of Q23L. Analysis of 3-D structure and sequence similarity were used to reveal the presumable factors influencing the enzymatic properties of Q23LG272E, and discussion for the relationship between structure and function of phytase was given.


Subject(s)
6-Phytase , Chemistry , Genetics , Metabolism , Amino Acid Substitution , Aspergillus fumigatus , Genetics , Biocatalysis , Electrophoresis, Polyacrylamide Gel , Fungal Proteins , Chemistry , Genetics , Metabolism , Hydrogen-Ion Concentration , Models, Molecular , Mutagenesis, Site-Directed , Mutant Proteins , Genetics , Metabolism , Mutation , Pichia , Genetics , Polymerase Chain Reaction , Protein Conformation , Protein Engineering , Methods , Recombinant Proteins , Metabolism , Structure-Activity Relationship , Substrate Specificity
19.
Chinese Journal of Biotechnology ; (12): 1017-1021, 2007.
Article in Chinese | WPRIM | ID: wpr-276169

ABSTRACT

A gene appA encoding a novel phytase was firstly cloned from Hafnia alvei by PCR and sequenced. The gene was consisted of 1335 bp, encoding 444 amino acids. The calculated molecular weight of the mature APPA was about 45.2 kD. The gene appA was expressed in E. coli BL21 (DE3). Recombinant APPA was purified and its enzymatic properties were determined. The optimum pH for the enzyme was 4.5 and the optimum temperature was 60 degrees C. The pH stability of r-APPA is good, the relative phytase activity was above 80% after treated in buffers of pH 2.0-10.0. The specific activity of r-APPA is 356.7 U/mg, and the Km value was 0.49 mmol/L and Vmax of 238 U/mg. The enzyme showed resistance to pepsin and trypsin treatment.


Subject(s)
6-Phytase , Genetics , Amino Acid Sequence , Cloning, Molecular , Escherichia coli , Genetics , Metabolism , Hafnia , Genetics , Hydrogen-Ion Concentration , Molecular Sequence Data , Recombinant Proteins , Genetics , Metabolism , Temperature
20.
Article in Chinese | WPRIM | ID: wpr-348029

ABSTRACT

<p><b>OBJECTIVE</b>To compare the wear between the enamel and two types of dental decoration porcelains for all-ceramic restorations (Vita-alpha, Vintage AL).</p><p><b>METHODS</b>Friction coefficients, wear scar width, element concentrations and wear surface evolution were considered relatively to the tribology of that in vivo situation. The wear scars of the samples were characterized by means of dynamic atomic force microscopy (DFM). The different element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS).</p><p><b>RESULTS</b>The friction coefficient varied from time in each kind of material. The statistical differences between materials were observed in wear scar width and properties of materials (P<0.05). DFM results showed wear surface of natural tooth full of abrasive particles and denaturation of dental texture. Wear surface of veneering ceramics consisted mainly of abrasive particles, plough and microcracking. EDS results showed that the element concentration of Fe was obviously found on the samples after wear.</p><p><b>CONCLUSION</b>The main underlying mechanisms of natural teeth wear are abrasive, and denaturation of dental texture. Abrasive wear, adhesion and fatigue of veneering ceramics characterize the wear patterns which plays different role in Vita-alpha and Vintage AL. The wear patterns of veneering ceramics can be described as mild wear.</p>


Subject(s)
Ceramics , Dental Enamel , Dental Porcelain , Dental Restoration Wear , Materials Testing , Surface Properties , Tooth Attrition
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