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Biomedical subjects

Yan Yang

Publications and source records attributed to Yan Yang.

At least 73 records · Page 4Linked to original sources
PubMed2005

DCCP and DICP: construction and analyses of databases for copper- and iron-chelating proteins.

Copper and iron play important roles in a variety of biological processes, especially when being chelated with proteins. The proteins involved in the metal binding, transporting and metabolism have aroused much interest. To facilitate the study on this topic, we constructed two databases (DCCP and DICP) containing the known copper- and iron-chelating proteins, which are freely available from the website http://sdbi.sdut.edu.cn/en. Users can conveniently search and browse all of the entries in the databases. Based on the two databases, bioinformatic analyses were performed, which provided some novel insights into metalloproteins.

Animals↗
PubMed2005

[Regulation of calcium-activated potassium channels of mesenteric artery smooth muscle from patients with essential hypertension by endothelin-1 and prostagl E1].

OBJECTIVE: To study regulation of Ca(2+)-activated K(+) channels (KCa) of mesenteric artery smooth muscle cell (SMC) from 21 old patients with essential hypertension (EH) by endothelin-1 (ET-1) and prostagl E(1) (PGE(1)). METHODS: Mesenteric artery branch from EH was digested by enzyme. Patch clamp technique was used to pull cell-attached and inside-out patches on mesenteric artery SMC from EH and the normotensive patients respectively. The signal channel open probability (Po), open dwell-time (To) and close dwell-time (Tc), open channel number per patch were recorded. After adding Ca(2+) (10(-8) approximately 10(-6) mol/L), ET-1(2 approximately 8 x 10(9) mol/L) and PGE(1) (10, 20, 40, 100, 200, 400 nmol/L) to cytoplasm respectively. The parameters above were observed again. RESULTS: Compared to that of normotensive patients, the activities of KCa channels of patients with EH was higher. After adding Ca(2+) to cytoplasm,the Po of KCa channels in normotensive patients increased significantly. But it was few changes in EH group. KCa channels has dual reaction to ET-1 in normotensive patients. We have found no statistics difference when ET-1 present on KCa channels of EH cases. Whereas PGE(1) can affect KCa channels current and channels kinetic significantly in side-out patches. The Po of KCa channels increased. The To protracted and the Tc curtailed in EH. CONCLUSIONS: The activities of KCa channels of patients with EH increased significantly. but the sensitive to Ca(2+) decreased. ET-1 were few effect to KCa channels. The PGE(1) can activated KCa channels of patients with EH.

Aged↗
PubMed2005

[Fracture resistence force of the cement-expanded composite screw post-core system].

OBJECTIVE: This is a study comparing the effects of different post designs on the fracture resistence. METHODS: Twenty-seven simulated tooth roots made of polymethyl methacrylate (PMMA) were divided into three groups, then the cement-expanded composite screw post-core system (CECSP), cement screw post-core system (CSP) and cast metal post-core system (CMP) were manufactured. The root and post-core system was compressed by the speed of 1 mm/min on the Instron 4302 and the fracture resistence force was recorded. RESULTS: Statistical analysis of the measured values showed the fracture resistence force of CECSP and CMP to be significantly greater than that of CSP (P < 0.05), but there was no significant difference between the fracture resistence force of CECSP and CMP (P > 0.05). CONCLUSION: The fracture mechanical properties of CECSP are much better than those of cement screw post-core system and are similar to cast metal post-core system. Therefore, it is possible to find a new way for restoration of endodontally treated teeth.

Composite Resins↗
PubMed2005

[Regulatory effect of IL-10 on expression of tissue factor induced by IL-6 in peripheral blood mononuclear cells].

To investigate the role of anti-inflammatory cytokine in acute coronary syndrome (ACS), the effect of IL-10 on expression of tissue factor (TF) induced by IL-6 in peripheral blood mononuclear cells (PBMNC) were studied. PBMNC were allowed to culture with rhIL-10 before being stimulated by rhIL-6. One-step recalcification clotting time was used to evaluate procoagulant activity (PCA) of PBMNC. The expression and activity of TF protein were determined by ELISA and cell chromogenic substrate assay. The results showed that the expression of PCA, TF protein and its activity in PBMNC increased significantly after being stimulated by rhIL-6 (P < 0.01). In PBMNC, rhIL-6-induced PCA was regulated by rhIL-10 in different doses. This effect was associated with reduction of TF protein expression and activity by rhIL-10 (P < 0.01). In conclusion, IL-10 down-regulated expression PCA and TF in PBMNC, inhibitory effect of IL-10 on expression and activity of PBMNC TF may be important protective mechanism for ACS, regulation imbalance between inflammatory and anti-inflammatory cytokines may be important factor participating in coronary thrombosis.

Cells, Cultured↗
PubMed2005

[Increased levels of advanced oxidation protein products are associated with atherosclerosis in chronic kidney disease].

OBJECTIVE: Accumulation of advanced oxidation protein products (AOPP) has been found in patients with chronic kidney disease (CKD). The study was performed to investigate the association between serum levels of AOPP and atherosclerosis in CKD. METHODS: 109 CKD patients were involved in this cross-sectional cohort study. Carotid artery intima-medial thickness (IMT), cross-sectional calculated intima-media area (cIM area) and plaques were determined with non-invasive high-resolution B-mode ultrasonography. Serum levels of AOPP, malonyldialdehyde (MDA), glutathione peroxidase (GSHPx) and C-reactive protein (CRP) were also determined. RESULTS: Higher serum AOPP levels were found in patients with CKD [(64.72 +/- 19.69) micromol/L] as compared with those in healthy controls [(30.16 +/- 6.46) micromol/L, P < 0.01]. AOPP levels in dialysis patients [(70.02 +/- 16.51) micromol/L] were significantly higher than those in pre-dialysis patients [(51.71 +/- 15.53) micromol/L, P < 0.01]. AOPP levels increased with the progression of renal dysfunction and inversely correlated with creatinine clearance (Ccr) (r = -0.292, P < 0.05). Patients with carotid artery plaques showed significantly higher levels of AOPP [(73.87 +/- 19.40) micromol/L] as compared with patients without carotid artery plaques [(58.41 +/- 16.09) micromol/L, P < 0.01]. Serum levels of AOPP were strongly associated with carotid artery IMT (r = 0.332, P < 0.01) and cIM area (r = 0.288, P < 0.05). By stepwise multiple regression analysis and adjusting for age, gender, blood pressure, smoking, diabetes, body mass index (BMI), hemoglobin, lipid and albumin, strong association was still present between AOPP levels and carotid artery IMT (beta = 0.313, P < 0.001) and cIMarea (beta = 0.301, P < 0.01). Serum levels of AOPP were correlated positively with serum MDA (r = 0.300, P = 0.01) and CRP levels (r = 0.255, P < 0.05), while negatively with serum GSHPx (r = -0.647, P < 0.01). CONCLUSIONS: Serum levels of AOPP increased with the progression of renal failure and closely associated with occurrence of atherosclerosis. Strong association between serum AOPP and CRP suggests that AOPP might be involved in the pathogenesis of micro-inflammation which has been considered as a contributing factor for atherosclerosis in CKD.

Adult↗
PubMed2005

[Effects of post diameter on retention of post-core crown system].

OBJECTIVE: To access the effects of post's diameter on the retention of post-core restorations. METHODS: Thirty-three simulant roots with same length,taper and different diameter (1.305 mm, 1.830 mm, 2.175 mm and 2.700 mm respectively) were made of polymethylmethacrylate and were divided into 4 groups. The wax patterns of post-cores were manufactured and cast. The post-cores were cemented. After that, the adhesion, frictional force and restriction of the post-core restorations were measured. RESULTS: When the proportion of length and diameter was smaller than 4.372, the linear regression between the post's diameter and the retention of post-core crown system was F = 107.98 + 72.08D. The linear regression between the post's diameter and the adhesion was P = 9.60 + 2.22D. The linear regression between the post's diameter and the frictional force and restriction was Q = 98.37 + 69.87D. The statistical analysis of the results indicated significant difference (P < 0.05). When the proportion of length and diameter was lager than 4.372, the retention of post-core crown system increased although the post's diameter decreased. CONCLUSION: When the proportion of length and diameter was smaller than 4.372, the retention of post-core crown system increased with the decrease of the post's diameter. While the proportion was lager than a certain value, this rule did not exist.

Crowns↗
PubMed2005

[Effect of cone angle on fracture resistance force of root and post-core system].

OBJECTIVE: To study the effect of cone angle on fracture resistance force of root and post-core system. METHODS: Forty-two simulated tooth roots made of polymethacrylate (PMMA) were divided into six groups according to the root canal cone angles of 0 degrees, 3.93 degrees, 5.71 degrees, 7.48 degrees, 11.31 degrees and 14.71 degrees. Cast post and cores were manufactured and cemented with zinc polycarboxylate cement (PC). Casting the post and core to restore every simulated tooth root. Each specimen was embedded in acrylic resin and then fixed in a special jig on the universal load-testing machine. A compressive load was applied at a 90-degree angle to the long axis of the core until fracture, at a crosshead speed of 1 mm/min. The maximum of load was recorded. RESULTS: The mean values of load in root and post-core system were 0.1225 kN, 0.1498 kN, 0.1600 kN, 0.1893 kN, 0.1078 kN and 0.0945 kN. There were significant differences in the fracture resistance among groups. CONCLUSION: The fracture resistance force of cast post and core increased with the enlargement of post cone angles under certain conditions.

Crowns↗
PubMed2005

[Detection of mutants of the "a" determinant region of hepatitis B surface antigen S gene among Wuhan childhood patients].

OBJECTIVE: To investigate whether the presence of HBV mutant in vaccinees simply reflects the prevalence of HBV mutant in a specific geographic area or is indeed due to the immune pressure induced by vaccination. METHODS: HBV S genes were amplified by using polymerase chain reaction (PCR) and DNA sequence analysis of the "a" determinant was performed on sera from 30 childhood patients with immunoprophylaxis and 30 patients without vaccinations. RESULTS: Mutations of the "a" determinant were detected in 8 of the 60 patients. They were all of the adw subtype. The prevalence of amino acid substitutions as detected by direct sequencing was higher in those fully-vaccinated than of those not vaccinated. In all 8 vaccinated and also with detectable mutants, the mean age was older than the other vaccinated children. CONCLUSION: The prevalence of mutants is related to HBV subtypes and genotypes. Universal vaccination has accelerated an accumulation of HBsAg "a" determinant mutants with amino acid changes critical for immune escape in vaccinated children who became carriers. This suggests that new vaccination strategies should be considered.

Child↗
PubMed2005

[Hemorheologic changes in patients with chronic hepatitis B].

OBJECTIVE: To study the variation of the hemorheology in patients with chronic hepatitis B and study its relations with HBV DNA, liver function and oxidative stress markers. METHODS: Indices for hemorheology, oxidative stress markers, liver function, and HBV DNA were measured in 55 patients with chronic hepatitis B and correlative analysis was made. RESULTS: The low-shear whole blood viscosity (BV), RBC aggregation index were significantly higher in hepatitis B group than those in the control group (P < 0.05), Hematocrit (HCT), the low-shear BV, RBC aggregation index were significantly higher in the patients whose ALT was higher than the patients whose ALT was normal and the controls. No significant difference was found in HBV DNA and indices of hemorheology (P > 0.05), nor in indices of hemorheology and oxidative stress markers (P > 0.05). CONCLUSION: There is disturbance of microcirculation and oxidative stress in the body of patients with chronic hepatitis B. The hemorheology and oxidative stress markers should be regarded as useful indexes in patients with chronic hepatitis B in addition to HBV markers.

Adolescent↗
PubMed2005

[Effects of post length on the dislocation of post and core crown].

OBJECTIVE: To evaluate the effects of the length of post on the dislocation of cast post and core crown. METHODS: Forty simulated tooth roots made of polymethyl methacrylate were divided into five groups according to different length of post. These cast post and core were bonded with zinc phosphate cement. Then these specimens were strectched on the INSTRON-4302 by the speed of 10 mm/min. The maximum of load was recorded. RESULTS: The loads of 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm were (203.25 +/- 57.19) N, (213.63 +/- 45.06) N, (234.44 +/- 59.27) N, (317.75 +/- 60.94) N, (334.25 +/- 58.00) N respectively. Linear regression analysis revealed the linear relationship of post length with dislocation, bonding, and mechanical interlocking; the values of r being 0.676, 1.000, 0.949; the regression equations being D = 73.225L - 325.776, B = 0.442L + 9.951, M = 72. 676L-334. 338. CONCLUSION: Mechanical interlocking is the main factor in dislocation of post and core crown. The length of post should be increased from 2/3 to 3/4 of the length of tooth root when prepared in clinic.

Crowns↗
PubMed2005

[Effects of expansion fashion and expansion quantity on retention of cement-expanded composite screw post].

OBJECTIVE: To study the effects of expansion fashion and expansion quantity on retention of cement-expanded composition screw post (CECSP). METHODS: Ninety simulated tooth roots made of polymethylmethacrylate were divided into ten groups, each fashion induded five groups. The expanded plastic sheath of tricuspid valve was made with the special separated valve device and cemented and tightened up into root with the screw post at the same time by ZPC. Then the root and screw post-core system was tested by the speed of 10 mm/min on the INSTRON 4302 and the retention force was recorded. RESULTS: It appeared that the difference between different expansion fashion and different expansion quantity were significantly (P < 0.05). The retention of expansion fashion one was significantly greater than those of fashion two. The retention was best when expansion quantity was within 10%. CONCLUSION: During clinic operation, we should apply definite fashion and control the expansion quantity within 10%, and the screw post should tighten up to the bottom of prepared root.

Bone Screws↗
PubMed2005

[Effects of the loss of alveolar bone on the areas of periodontal ligament, mechanical fulcrum and fracture resistance of root and post-core system].

OBJECTIVE: To assess the effects of loss of alveolar bone on the areas of periodontal ligament (PL), mechanical fulcrum and fracture resistance of root and post-core system. METHODS: One hundred and eight simulated roots in the same length, taper and diameter were made of polymethylmethacrylate and were divided into 13 groups. Then the wax patterns of post-cores were casted and cemented. Each specimen was embedded in acrylic resin in accordance with different loss of alveolar bone and different mechanical fulcrum. Base on the anatomic and physiological special features of the periodontal tissues, three mechanical methods were designed. The compress test was run by the speed of 1 mm/min and the fracture resistance was recorded. The areas of periodontal ligament were measured and calculated. RESULTS: When the loss of alveolar bone and the mechanical fulcrum were 0 mm and 12/12 group, 1 mm and 11/12 group, 2 mm and 10/12 group, 3 mm and 9/12 group, 3.5 mm and 8.5/12 group, 4 mm and 8/12 group, 4.5 mm and 7.5/12 group, 5 mm and 7/12 group,5. 5 mm and 6.5/12 group, 6 mm and 6/ 12 group, 7 mm and 5/12 group, 8 mm and 4/12 group, 9 mm and 3/12 group, the means of the areas of PL (mm2) and fracture resistance (N) were 178.95 and 232. 90 +/- 25. 93, 159. 64 and 195.58 +/- 12.46, 141.18 and 173.92 +/- 13.51, 123.27 and 154.00 +/- 11.74, 106.14 and 123.25 +/- 14.29, 89.67 and 96.86 +/- 6. 20, 73.90 and 59.14 +/- 7.28, 58.82 and 52.52 +/- 5. 82, 44.44 and 45.90 +/- 7.40, 30.76 and 58.60 +/- 6.63 (mm, N). The linear correlations were found between the percentage of the loss of alveolar bone and surplus areas of PL, the loss of alveolar bone and the fracture resistance of root and post-core system, the percentage of the areas of PL and the fracture resistance of root and post-core system, the distance of the fulcrum and the percentage of the loss of alveolar bone. CONCLUSION: The loss of alveolar bone caused the decrease in areas of PL, the dessent of mechanical fulcrum, and the diminution of the fracture resistance of root and post-core system.

Alveolar Bone Loss↗
PubMed2004

Functional characterization of fidgetin, an AAA-family protein mutated in fidget mice.

The mouse fidget mutation is an autosomal recessive mutation that renders reduced or absent semicircular canals, microphthalmia, and various skeletal abnormalities to affected mice. We previously identified the defective gene which encodes fidgetin, a new member of the ATPases associated with diverse cellular activities (AAA proteins). Here, we report on the subcellular localization of fidgetin as well as that of two closely related proteins, fidgetin-like 1 and fidgetin-like 2. Epitope-tagging and immunostaining revealed that both fidgetin and fidgetin-like 2 were predominantly localized to the nucleus, whereas fidgetin-like 1 was both nuclear and cytoplasmic. Furthermore, deletion studies identified a putative bipartite nuclear localization signal in the middle portion of the fidgetin protein. Since AAA proteins are known to form functional hetero- or homo-hexamers, we used reciprocal immunoprecipitation to examine the potential interaction among these proteins. We found that fidgetin interacted with itself and this specific interaction was abolished when either the N- or C-terminus of the protein was truncated. Taken together, our results suggest that fidgetin is a nuclear AAA-family protein with the potential to form homo-oligomers, thus representing the first step towards the elucidation of fidgetin's cellular function and the disease mechanism in fidget mutant mice.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2004

Imbalanced plasminogen system in lymphangioleiomyomatosis: potential role of serum response factor.

Pulmonary lymphangioleiomyomatosis (LAM) is characterized by abnormal smooth muscle-like cell (LAM cell) proliferation leading to tissue destruction. We previously demonstrated that serum response factor (SRF), a critical smooth muscle transcription factor, is highly expressed in LAM cells. Here we show that a high SRF level alters the plasminogen (Plg) system. Specifically, overexpression of SRF in human lung fibroblasts upregulated urokinase-type plasminogen activator (uPA) and its substrate Plg, whereas it downregulated plasminogen activator inhibitor (PAI)-1. Because uPA cleaves Plg into plasmin, which activates matrix metalloproteinases (MMP), the end result was an increase in MMP activity. To determine whether uPA, Plg, and PAI-1 were abnormally expressed in LAM in vivo, we immunostained 12 LAM cases. In all cases, the LAM lesions showed stronger immunoreaction for uPA and Plg than the surrounding normal lung parenchyma. On the contrary, PAI-1 was absent in LAM lesions, whereas it was ubiquitous in normal lung parenchyma. Microdissection-based reverse transcriptase/polymerase chain reaction further confirmed upregulation of uPA and Plg and downregulation of PAI-1 message in LAM. Altogether, our findings suggest that the high SRF level seen in LAM contributes to extracellular matrix degradation and progressive LAM cell infiltration of the lung.

Cell Proliferation↗
PubMed2004

GDF-3 is an adipogenic cytokine under high fat dietary condition.

Growth differentiation factor 3 (GDF-3) is structurally a bone morphogenetic protein/growth differentiation factor subfamily member of the TGF-beta superfamily. GDF-3 exhibits highest level of expression in white fat tissue in mice and is greatly induced by high fat diet if fat metabolic pathway is blocked. To identify its biological function, GDF-3 was overexpressed in mice by adenovirus mediated gene transfer. Mice transduced with GDF-3 displayed profound weight gain when fed with high fat diet. The phenotypes included greatly expanded adipose tissue mass, increased body adiposity, highly hypertrophic adipocytes, hepatic steatosis, and elevated plasma leptin. GDF-3 stimulated peroxisome proliferator activated receptor expression in adipocytes, a master nuclear receptor that controls adipogenesis. However, GDF-3 was not involved in blood glucose homeostasis or insulin resistance, a condition associated with obesity. In contrast, similar phenotypes were not observed in GDF-3 mice fed with normal chow, indicating that GDF-3 is only active under high lipid load. Thus, GDF-3 is a new non-diabetic adipogenic factor tightly coupled with fat metabolism.

3T3-L1 Cells↗
PubMed2004

Genetic basis of tobacco smoking: strong association of a specific major histocompatibility complex haplotype on chromosome 6 with smoking behavior.

The genetic basis for addiction to tobacco smoking--particularly that of the perception of olfactory stimuli that may be important in reinforcing smoking addiction--is largely unknown. A cluster of genes for olfactory receptors is in close proximity to the MHC region on chromosome 6. Polymorphisms of MHC class III genes (RCCX modules, TNFA promoter polymorphisms) were determined in 101 healthy subjects and 232 coronary artery disease (CAD) patients from Hungary with defined tobacco smoking habits. A highly significant association between ever smoking (past + current smokers) and a specific MHC haplotype was observed (odds ratios = 2.14-4.13; P-values = 0.012 to <0.001). This haplotype is characterized by the presence of C4A null alleles and a solitary short C4B gene linked to the TNF2 allele of the promoter for TNFA gene. This haplotype occurred more frequently in the ever smokers than in the never smokers [odds ratio: 4.97 (1.96-12.62); P = 0.001], and such associations were stronger in women (odds ratio = 13.6) than in men (odds ratio = 2.79). An independent study of complement C4 protein polymorphism and smoking habits in Icelandic subjects (n = 351) yielded similar and confirmative results. Considering the documented link between olfactory stimuli and smoking in females, and the presence of a cluster of odorant receptor genes close to the MHC class I region, our findings implicate a potential role of the MHC-linked olfactory receptor genes in the initiation of smoking.

Adult↗
PubMed2004

High-resolution structure of a picornaviral internal cis-acting RNA replication element (cre).

Picornaviruses constitute a medically important family of RNA viruses in which genome replication critically depends on a small RNA element, the cis-acting replication element (cre), that templates 3D(pol) polymerase-catalyzed uridylylation of the protein primer for RNA synthesis, VPg. We report the solution structure of the 33-nt cre of human rhinovirus 14 under solution conditions optimal for uridylylation in vitro. The cre adopts a stem-loop conformation with an extended duplex stem supporting a novel 14-nt loop that derives stability from base-stacking interactions. Base-pair interactions are absent within the loop, and base substitutions within the loop that favor such interactions are detrimental to viral RNA replication. Conserved adenosines in the 5' loop sequence that participate in a slide-back mechanism of VPg-pUpU synthesis are oriented to the inside of the loop but are available for base templating during uridylation. The structure explains why substitutions of the 3' loop nucleotides have little impact on conformation of the critical 5' loop bases and accounts for wide variation in the sequences of cres from different enteroviruses and rhinoviruses.

Base Pairing↗