Biomedical subjects

Rui Tian

Publications and source records attributed to Rui Tian.

13 recordsLinked to original sources

PubMed2026

Dissecting the genetic basis underlying drought tolerance at different development stages in soybean.

INTRODUCTION: Soybean is an indispensable crop supplying protein and oil for humans and animals, and playing an essential role in global food security. Drought represses soybean seed germination, reducing biomass accumulation and even inhibiting yield. METHODS: In order to dissect the genetic components underlying soybean drought tolerance during different development stage, a natural population containing 140 accessions was employed to evaluate seven drought tolerance-related traits under water-welled and drought stress conditions. Subsequently, genome-wide association study (GWAS) was conducted based on 150K single nucleotide polymorphism (SNP) markers of "Zhongdouxin-1". And the drought tolerance coefficient of seven different traits were analyzed with seven GWAS models. RESULTS: A total of 1807 significant SNPs were detected across 20 chromosome, including 569 SNPs for germination stage, and 1242 SNPs for seedling stage. Of 569 SNPs identified in germination stage, 354 SNPs on chromosomes 2, 7, 13, 14, and 17 accounting for 62.21%. Among 1242 SNPs found in seedling stage, 869 SNPs on chromosomes 11, 14, 15, 17 and 18 accounting for 69.97%. Moreover, among 1807 significant SNPs, 163 SNPs exhibited pleiotropic effects, of which 23 were located in exon, 21 in intron, 12 in 5'UTR or 3'UTR and 11 in upstream or downstream. Furthermore, 249 stable SNPs were detected by more than four GWAS models. According to these stable SNPs, RNA expression levels and gene annotations, four causal genes (Glyma.02G080200, Glyma.11G056200, Glyma.12G188900, and Glyma.18G110200) conferring soybean drought tolerance were detected, which participated in ethylene stimulus response, water deprivation response, and proteolysis. DISCUSSION: Collectively, 249 stable SNPs, 163 pleiotropic SNPs and four candidate genes identified in present study provided promising molecular resources and reliable foundation for drought resistance improvement and marker-assisted selective breeding in soybean.

GWAS↗

PubMed2006

A high efficiency strategy for binding property characterization of peptide-binding domains.

A large proportion of protein-protein interactions is mediated by families of peptide-binding domains. Comprehensive characterization of each of these domains is critical for understanding the mechanisms and networks of protein interaction at the domain level. However, existing methods are all based on large scale screenings for each domain that are inefficient to deal with hundreds of members in major domain families. We developed a systematic strategy for efficient binding property characterization of peptide-binding domains based on high throughput validation screening of a specialized candidate ligand library using yeast two-hybrid mating array. Its outstanding feature is that the overall efficiency is dramatically improved compared with that of traditional screening, and it will be higher as the system cycles. PDZ domain family was first used to test the strategy. Five PDZ domains were rapidly characterized. Broader binding properties were identified compared with other methods, including novel recognition specificities that provided the basis for major revision of conventional PDZ classification. Several novel interactions were discovered, serving as significant clues for further functional investigation. This strategy can be easily extended to a variety of peptide-binding domains as a powerful tool for comprehensive analysis of domain binding property in proteomic scale.

Animals↗

PubMed2005

Gene transfer of somatostatin receptor type 2 by intratumoral injection inhibits established pancreatic carcinoma xenografts.

AIM: To investigate the therapeutic effect of somatostatin receptor type 2 (SSTR2) gene transfection on pancreatic carcinoma xenografts in vivo in experimental cancers. METHODS: Human pancreatic cancer cell line Panc-1 was inoculated subcutaneously into the back of nude mice. When tumor nodules were grown as large as about 5 mmX5 mm days after inoculation, the mice were randomly divided into 3 groups (6 mice in each group). Group I served as untreated control group. Group II received an intratumoral injection of a combination of human cytomegalovirus promoter-6C (pCMV-6C) and lipofectamine 2000. Group III received an intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000. The rate of tumor growth was compared among these three groups. The expression of SSTR2 in these tumors was detected by immunohistochemistry and Western-blot. Apoptosis index (AI) in these tumors was examined by using TUNEL in situ. RESULTS: Intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000 resulted in the expression of SSTR2 protein. The tumor size and weight in group III (0.318+/-0.098 cm3, and 0.523+/-0.090 g, respectively) were significantly lower than those in group I (2.058+/-0.176 cm3, and 1.412+/-0.146 g, respectively) and group II (2.025+/-0.163 cm3, and 1.365+/-0.116 g, respectively) (P<0.05) The AI in group III (1.47+/-0.13%) was significantly higher than that in group I (0.56+/-0.09%) and group II (0.57+/-0.11%) (P<0.05). But there were no significant differences between groups I and II. CONCLUSION: Our data demonstrate that re-expression of SSTR2 gene has antitumor effects on experimental pancreatic cancer. Restoration of SSTR2 gene expression through gene transfer in vivo might be a potential gene therapy strategy for human pancreatic cancer.

Animals↗

PubMed2004

Neuronal tau induces DNA conformational changes observed by atomic force microscopy.

Neuronal tau associates with chromosome scaffold and localizes in the nuclear and the nucleolar organization regions in neuronal and some non-neuronal cells. Observing the interaction of neuronal tau with DNA under AFM shows that tau binds to DNA as a monomer, and tau-DNA complex forms a beads-on-a-string structure when the mass ratio is 1:10 (molar ratio of tau/DNA approximately 1:700 bp). A beads-on-a-coil structure, in which tau is as polymers, will appear when the mass ratio is up to 1:5 (molar ratio of tau/DNA approximately 1:350 bp). The present observation that neuronal tau bends the DNA double strands indicates that the appearance of the tau-DNA complex is dependent upon the mass (or molar) ratio of tau and DNA.

DNA↗

PubMed2004

The acidic C-terminal domain stabilizes the chaperone function of protein disulfide isomerase.

Protein disulfide isomerase (PDI, EC 5.3.4.1) is a chaperone and catalyzes the formation and rearrangement of disulfide bonds in proteins. Domain c-(463-491), containing 18 acidic residues, is an interesting and important C-terminal extension of PDI. In this study, the PDI mutant abb'a', in which domain c is truncated, was used to investigate the relationship between the C-terminal structure and chaperone function. Reactivation and light-scattering experiments show that both wild-type PDI and abb'a' interact with lactate dehydrogenase (LDH, EC 1.1.1.27), which tends to self-aggregate during reactivation. The interaction enhances reactivation of LDH and reduces aggregation. According to these results, it seems as if domain c might be dispensable to the chaperone function of PDI. However, abb'a' is prone to self-aggregation and causes increased aggregation of LDH during thermal denaturation. In contrast, wild-type PDI remains active as a chaperone under these conditions and prevents self-aggregation of LDH. Furthermore, measurements of intrinsic fluorescence and difference absorbance during denaturation show that abb'a' is much more labile to heat or guanidine hydrochloride denaturation than wild-type PDI. This suggests that domain c is required for the stabilization and maintenance of the chaperone function of PDI under extreme conditions.

Catalysis↗

PubMed2004

[Mechanisms of inhibition of growth of human pancreatic carcinoma implanted in nude mice by somatostatin receptor subtype 2].

OBJECTIVE: To investigate the antitumor effect of somatostatin receptor subtype 2 (SSTR2) gene transfection into pancreatic cancer cell line PC-3, and the mechanisms involved in this effect. METHODS: The full-length human SSTR2 cDNA was introduced into the pancreatic cancer cell line PC-3 by lipofect amine-mediated transfection. Positive clones were screened by G418 and stable expression of SSTR2 was detected by immunocytochemistry SABC method and RT-PCR. Fifteen athymic mice were randomly divided into 3 groups of 5 mice to be xenografted with SSTR2-expressing cells (experimental group), empty vector control group, and control group cells respectively. The weight of mice and the size of tumor were measured every week. Eight weeks later the mice were killed and the tumors were taken out. TUNEL assay was used to determine the apoptotic index (AI) in these tumors. Immunohistochemistry SP method was used to determine the expressions of apoptosis regulating genes, Bcl-2 and Bax, and intratumoral. microvessel density (MVD). Moreover, the tumor volume and weight were compared among these three groups. RESULTS: The AI was significantly higher in the experimental group (3.39% +/- 0.84%) compared with the empty vector control group (0.69% +/- 0.08%) and control group (0.68% +/- 0.09%) (both P < 0.05). The significant decrease in Bcl-2, and increase in Bax protein expressions were detected in the experimental group compared with the empty vector control group and control group (both P < 0.05). MVD was significantly lower in the experimental group (6.3 +/- 1.7) than those in the empty vector control group (12.6 +/- 1.7) and control group (13.5 +/- 1.9) (P < 0.05). Moreover, the tumor volume and weight were significantly lower in the experimental group as compared with the empty vector control group and control group (P < 0.05). However, no significant differences in all the indicators were observed between the empty vector control group and the control group (both P > 0.05). CONCLUSIONS: Re-expression of SSTR2 gene, the expression of which is frequently lost in human pancreatic adenocarcinoma, can induce apoptosis which may be mediated via down-regulation of Bcl-2 and up-regulation of Bax, and inhibit tumor angiogenesis in pancreatic carcinoma, resulting in inhibition of tumor growth.

Animals↗

PubMed2004

Chaperone-like manner of human neuronal tau towards lactate dehydrogenase.

In our experiments, inactivation of lactate dehydrogenase (LDH, EC1.1.1.27) in the presence of human microtubule-associated tau is observably suppressed during thermal and guanidine hydrochloride (GdnHCl) denaturation. Kinetic studies show tau can prevent LDH from self-aggregation monitored by light scattering during thermal denaturation. On the other hand, neuronal tau promotes reactivation of LDH and suppresses self-aggregation of non-native LDH when GdnHCl solution is diluted. Furthermore, the reactivation yield of LDH decreases significantly with delayed addition of tau. All experiments were completed in the reducing buffer with 1 mM DTT to avoid between tau and LDH forming the covalent bonds during unfolding and refolding. Thus, Tau prevents proteins from misfolding and aggregating into insoluble, nonfunctional inclusions and assists them to refold to reach the stable native state by binding to the exposed hydrophobic patches on proteins instead of by forming or breaking covalent bonds. Additionally, tau remarkably enhances reactivation of GDH (glutamic dehydrogenase, EC 1.4.1.3), another carbohydrate metabolic enzyme, also showing a chaperone-like manner. It suggests that neuronal tau non-specifically functions a chaperone-like protein towards the enzymes of carbohydrate metabolism.

Animals↗

PubMed2004

Mechanisms of inhibition of growth of human pancreatic carcinoma implanted in nude mice by somatostatin receptor subtype 2.

OBJECTIVES: Several studies reported that somatostatin receptor subtypes, especially subtype 2 (SSTR2), exerted their cytostatic and/or cytotoxic effects on various types of tumors. The aim of this study was to investigate the antitumor effect of SSTR2 gene transfer to the pancreatic cancer cell line PC-3 and the mechanisms involved in this effect. METHODS: The full-length human SSTR2 cDNA was introduced into pancreatic cancer cell line PC-3 by lipofectamine-mediated transfection; positive clones were screened by G418, and stable expression of SSTR2 was detected by the immunohistochemical SABC method and RT-PCR. Athymic mice were separately xenografted with SSTR2-expressing cells (experimental group), vector control, and mock control cells. TUNEL assay was used to determine the apoptotic index (AI) in the tumors of these groups. The immunohistochemical SP method was used to determine expression of apoptosis-regulating genes Bcl-2 and Bax and re-expression of SSTR2 and to assess intratumoral microvessel density (MVD). Moreover, tumor volume and weight were compared among these 3 groups. RESULTS: Restoration of SSTR2 was observed in the experimental group both in vitro and in vivo. The AI was significantly higher in the experimental group (3.39 +/- 0.84%) compared with that in the vector control (0.69 +/- 0.08%) and mock control (0.68 +/- 0.09%) (P < 0.05). MVD was significantly lower in the experimental group (6.30 +/- 1.71) than that in the vector control (12.64 +/- 1.69) and mock control (13.50 +/- 1.86) (P < 0.05). Furthermore, a significant decrease in Bcl-2 and increase in Bax protein expression were detected in the experimental group compared with the vector control and mock control (P < 0.05). A significant negative correlation of protein expression between Bcl-2/Bax ratio and SSTR2 was observed in these tumors (P < 0.05). Tumor volume and weight were significantly decreased in the experimental group compared with the vector control and mock control (P < 0.05) groups. However, no significant differences were observed between the vector control and mock control (P > 0.05). CONCLUSION: Re-expression of the SSTR2 gene, the expression of which is frequently lost in human pancreatic adenocarcinoma, induces apoptosis, which may be mediated via down-regulation of Bcl-2 and up-regulation of Bax (alteration of Bcl-2/Bax ratio) and inhibits tumor angiogenesis in pancreatic carcinoma, resulting in inhibition of tumor growth.

Adenocarcinoma↗

PubMed2004

[Drug screening model acting on out-membrane protein OprM in pseudomonas aeruginosa efflux pump system].

OBJECTIVE: To establish an efflux pump inhibitor screening model with the out-membrane protein OprM in Pseudomonas aeruginosa efflux pump system as the target point. METHODS: Efflux pump out-membrane protein gene oprM was obtained from standard Pseudomonas aeruginosa PA01 strain. Expression of OprM protein was induced in E. coli strain HS151 with T-easy vector as the cloning vector, and pMMB67EH as the expression vector. In order to evaluate the function of OprM protein, we measured intracellular tetracycline concentrations with liquid scintillation counter, measured the diameters of bacteriostatic circles with paper disc, and then established a screening model accordingly. RESULTS: OprM protein was highly expressed. Using Pseudomonas aeruginosa as the main detecting bacteria, we established a drug screening model acting on OprM. A total of 1 600 microbial fermentation samples were screened with this model, among which 56 positive strains were found, with a positive rate of 3.5%. CONCLUSION: OprM plays an important role in drug efflux. The established model has good specificity and maneuverability.

Anti-Bacterial Agents↗

PubMed2003

Peptides that regulate food intake: appetite-inducing accumbens manipulation activates hypothalamic orexin neurons and inhibits POMC neurons.

Corticolimbic circuits involving the prefrontal cortex, amygdala, and ventral striatum determine the reward value of food and might play a role in environmentally induced obesity. Chemical manipulation of the nucleus accumbens shell (AcbSh) has been shown to elicit robust feeding and Fos expression in the hypothalamus and other brain areas of satiated rats. To determine the neurochemical phenotype of hypothalamic neurons receiving input from the AcbSh, we carried out c-Fos/peptide double-labeling immunohistochemistry in various hypothalamic areas known to contain feeding peptides, from rats that exhibited a significant feeding response after AcbSh microinjection of the GABA(A) agonist muscimol. In the perifornical area, a significantly higher percentage of orexin neurons expressed Fos after muscimol compared with saline injection. In contrast, Fos expression was not induced in melanin-concentrating hormone and cocaine-amphetamine-related transcript (CART) neurons. In the arcuate nucleus, Fos activation was significantly lower in neurons coexpressing CART and proopiomelanocortin, and there was a tendency for higher Fos expression in neuropeptide Y neurons. In the paraventricular nucleus, no significant activation of oxytocin and CART neurons was found. Thus AcbSh manipulation may elicit food intake through coordinated stimulation of hypothalamic neurons expressing orexigenic peptides and suppression of neurons expressing anorexigenic peptides. However, activation of many neurons not expressing these peptides suggests that additional peptides/transmitters in the lateral hypothalamus and accumbens projections to other brain areas might also be involved.

Animals↗

PubMed2003

Effects of different therapies on coronary artery disease.

OBJECTIVE: To analyse the effects of different therapies on coronary artery disease (CAD). METHODS: A total of 1055 patients who suffered from CAD diagnosed by coronary angiography were divided into three groups, namely pure drug therapy, percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) groups. Follow up was carried out from March to May in 2001, and the major adverse cardiac events (MACEs) including death, no-lethal myocardial infarction (MI) and revascularization were observed. In long-term observation, angina reoccurred, and their improvement was evaluated. The short-term period was defined as the duration of 30 days after discharge, and the long term period was defined as the duration from 30 days after discharge. RESULTS: In the long-term period, the recurrences of angina both in PCI group and CABG group were lower than pure drug group (P 0.018, 0.002 respectively). No differences about long-term endpoint events were observed among these three groups (P > 0.05). Forty-two patients suffering from left main coronary disease were intervened by the three therapies, and there was no death or MI both in PCI and CABG groups, three patients died and suffered from AMI in pure drug therapy group (P = 0.015). In the short-term period, mortality in CABG group (5.77%) was higher than those in the other two groups (1.91% for PCI, and 1.40% for medical therapy, P = 0.002), and no obvious difference observed in the latter two groups. No significance was concluded about the recent MI among this three groups (P = 0.357). There were no differences on revascularization in these three groups. CONCLUSIONS: Percutaneous coronary interventions can not only reduce the attack of angina but also improve the life quality of patients, however it can not improve the long-term existence but left main CAD.

Adult↗

PubMed2003

Evaluation of transisthmus conduction interval in predicting bidirectional block after ablation of typical atrial flutter.

OBJECTIVE: To determine whether the extent of prolongation of the transisthmus interval after ablation predicts complete bidirectional block. METHODS: Since 1996 to 2002, 30 consecutive patients underwent ablation procedures for isthmus-dependent atrial flutter. There were 23 males and 7 females [mean age (47.85 +/- 9.35) years]. With the use of fluoroscopic view of anatomy, radiofrequency ablation was performed during coronary sinus pacing at a cycle length of 600 ms. RESULTS: Bidirectional block was achieved with ablation in 29 (97%) of 30 patients. The transisthmus intervals before ablation and after complete transisthmus block were (73.82 +/- 13.01) ms and (140.47 +/- 20.48) ms, respectively, in the clockwise direction (P < 0.0001), and (77.63 +/- 8.36) ms and (138.17 +/- 15.55) ms, respectively, in the counterclockwise direction (P < 0.0001). A period of incomplete isthmus block was observed during 17 (58%) of the 29 ablation procedures. The clockwise transisthmus intervals during incomplete block [(107.65 +/- 21.33) ms] were (45.5 +/- 8.7)% longer than the baseline transisthmus intervals. An increase in the transisthmus interval by > or = 50% in both directions after ablation predicted complete bidirectional block with 100.0% sensitivity and 83.3% specificity. The positive and negative predictive values were 90.6% and 100.0%, respectively. The diagnostic accuracy of a > or = 50% prolongation in the transisthmus interval was 83.3%. CONCLUSION: The analysis of transisthmus interval is a valuable method for determining complete bidirectional isthmus block.

Atrial Flutter↗

PubMed2002

Role of the area postrema of medulla oblongata in the regulation of canine interdigestive migrating motor complex.

OBJECTIVE: To determine the effect of the area postrema (AP) of the medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC) and the plasma motilin level. METHODS: Interdigestive MMC activities of the antrum and duodenum were recorded by strain gauge implanted on the serosa of 8 conscious dogs. A cannula was intubated in femoral vein for motilin injection. The plasma motilin concentration was measured by RIA. We observed: (1) normal interdigestive MMC activity and fluctuations in plasma motilin concentration; (2) the effects of electrically damaging the AP on MMC activity and plasma motilin level; (3) whether intravenous injection of motilin could induce phase III contractions after the AP was destroyed. RESULTS: (1) Typical interdigestive MMC with phase I, II, III, and IV was recorded in normal dogs. Phase III was concurrent with the peak of plasma motilin level. (2) In damaged AP dogs, antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase III contractions. CONCLUSIONS: The area postrema might play an important role, which is mediated by motilin, on the regulation of interdigestive MMC.

Animals↗