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Biomedical subjects

Tao Peng

Publications and source records attributed to Tao Peng.

At least 37 records · Page 2Linked to original sources
PubMed2005

Chlamydia trachomatis variant with nonfusing inclusions: growth dynamic and host-cell transcriptional response.

We compared growth rate and host-cell transcriptional responses of a Chlamydia trachomatis variant strain and a prototype strain. Growth dynamics were estimated by 16S rRNA level and by inclusion-forming units (IFUs) at different times after infection in HeLa cells. When inoculated at the same multiplicity of infection and observed 24-48 h after infection, the variant 16S rRNA transcriptional level was 3%-4% that of the prototype, and the IFUs of the variant strain were 0.1%-1% those of the prototype. Specific host-cell transcriptional responses to the variant were identified in a global-expression microarray in which variant strain-infected cells were compared with mock-infected and prototype strain-infected cells. In variant strain-infected cells, 47% (16/34) of specifically induced host genes were related to immunity and 32% (8/25) of specifically suppressed genes were related to lipid metabolism. The variant strain grew significantly more slowly and induced a modified host-cell transcriptional response, compared with the prototype strain.

Chlamydia trachomatis↗
PubMed2005

Role of C5 in the development of airway inflammation, airway hyperresponsiveness, and ongoing airway response.

The role of complement component C5 in asthma remains controversial. Here we examined the contribution of C5 at 3 critical checkpoints during the course of disease. Using an mAb specific for C5, we were able to evaluate the contribution of C5 during (a) the initiation of airway inflammation, (b) the maintenance of airway hyperresponsiveness (AHR), and (c) sustainment of an ongoing airway response to allergen provocation. Our results indicate that C5 is probably activated intrapulmonarily after infections or exposures to allergen and C5 inhibition has profound effects at all 3 critical checkpoints. In contrast to an earlier report, C5-deficient mice with established airway inflammation did not have elevated AHR to nonspecific stimuli. In the presence of airway inflammation, C5a serves as a direct link between the innate immune system and the development of AHR by engaging directly with its receptors expressed in airways. Through their powerful chemotactic and cell activation properties, both C5a and C5b-9 regulate the downstream inflammatory cascade, which results in a massive migration of inflammatory cells into the bronchial airway lumen and triggers the release of multiple harmful inflammatory mediators. This study suggests that targeting C5 is a potential clinical approach for treating patients with asthma.

Animals↗
PubMed2005

A redox-sensitive pathway mediates oxidized LDL-induced downregulation of insulin-like growth factor-1 receptor.

Oxidized low density lipoprotein (OxLDL) has multiple proatherogenic effects, including induction of apoptosis. We have recently shown that OxLDL markedly downregulates insulin-like growth factor-1 receptor (IGF-1R) in human aortic smooth muscle cells, and that IGF-1R overexpression blocks OxLDL-induced apoptosis. We hypothesized that specific OxLDL-triggered signaling events led to IGF-1R downregulation and apoptosis. We examined OxLDL signaling pathways and found that neither IGF-1R downregulation nor the proapoptotic effect was blocked by inhibition of OxLDL-triggered extracellular signal-regulated kinase, p38 mitogen-activated protein kinase (MAPK), or peroxisome proliferator-activated receptor gamma (PPARgamma) signaling pathways, as assessed using specific inhibitors. However, antioxidants, polyethylene glycol catalase, superoxide dismutase, and Trolox completely blocked OxLDL downregulation of IGF-1R and OxLDL-induced apoptosis. Nordihydroguaiaretic acid, AA-861, and baicalein, which are lipoxygenase inhibitors and also have antioxidant activity, blocked IGF-1R downregulation and apoptosis as well as reactive oxygen species (ROS) production. These results suggest that OxLDL enhances ROS production possibly through lipoxygenase activity, leading to IGF-1R downregulation and apoptosis. Furthermore, anti-CD36 scavenger receptor antibody markedly inhibited OxLDL-induced IGF-1R downregulation and apoptosis as well as ROS production. In conclusion, our data demonstrate that OxLDL downregulates IGF-1R via redox-sensitive pathways that are distinct from OxLDL signaling through MAPK- and PPARgamma-involved pathways but may involve a CD36-dependent mechanism.

Antioxidants↗
PubMed2005

A new ligand binding to G-G mismatch having improved thermal and alkaline stability.

Naphthyridine dimer (ND) specially binds to guanine-guanine (G-G) mismatch in duplex DNA. In order to improve the thermal and alkaline stability and binding ability of the ligand, we have examined structural modification of the linker. A new ligand (NNC) possessing 2-amino-1,8-naphthyridines and a carbamate linker is much more thermally stable than ND. The half-life of NNC is 2.5 times longer than that of ND at 80 degrees C. NNC is also much more stable than ND under alkaline conditions. In addition, NNC binds to G-G mismatch more strongly than ND. The improved stability and the binding of NNC to the G-G mismatch would be suitable for the practical use of NNC-immobilized sensor.

Base Pair Mismatch↗
PubMed2005

Molecular labeling of the CGG trinucleotide repeat.

The new molecular ligand naphthyridine carbamate dimer (NC), possessing 2-amino-1,8-naphthyridines and a carbamate linker, specially binds to guanine-guanine (G-G) mismatch in duplex DNA. The results of T(m) measurements showed that NC selectively bound to CGG/CGG triad with high deltaT(m) of 23.1 degrees C. The exclusive stoichiometry 2:1 of the complex of NC with CGG/CGG triad, obtained by the measurements of cold spray ionization time-of-flight mass spectrometry (CSI-TOF MS), showed that NC bound to CGG/CGG triad strongly with two molecules.

Base Pair Mismatch↗
PubMed2005

[The expression of hTERT and p53 protein in pre-malignant and malignant lesions of human oral mucosa].

PURPOSE: To investigate the roles of hTERT and p53 protein in malignant changes of oral mucosal precancerous lesions and the relations between hTERT and p53. METHODS: The expression of hTERTmRNA and p53 were measured using in situ hybridization and immunohistochemical assay in 9 cases of oral mucosal hyperplasia, 11 cases of light dysplasia, 10 cases of medium dysplasia, 9 cases of carcinomas in situ and 11 cases of squamous cell carcinomas. The results were processed by medical photographic system, and analyzed statistically by one-way ANOVA. The relation to hTERT and p53 was analyzed statistically by Pearson correlations. RESULTS: It was found that from hyperplasia to light dysplasia, medium dysplasia, carcinomas in situ and squamous cell carcinomas, the indexes of positive cell vessels and the value of OD increased, arriving at the apex in squamous cell carcinoma. With phenotypic progression and the degree of dysplasia, hTERT and p53 expression cells extend from basal layer to the keratinous layer. In highly-differentiated squamous cell carcinomas, expression cells were mainly located around the nests. Stained cells dispersed throughout the tumor tissue in low-differentiated squamous cell carcinomas. p53 was undetectable in hyperplasia and light dysplasia, but p53 was observed in 66.67% cases of high dysplasia and 72.72% cases of squamous cell carcinomas. There was not a significant linear correlation between hTERT and p53. CONCLUSIONS: The results suggest that activation of telomerase and p53 play a role in the process of malignant changes of oral mucosal precancerous lesions. Oral squamous cell carcinoma is a disease that has been found in association with many factors.

Carcinoma in Situ↗
PubMed2005

[The effect of ribozyme specially cleaving per1 mRNA on c-fos mRNA and its expression in hippocampus of morphine addicted mice].

OBJECTIVE: To study the change of c-fos mRNA and protein in hippocampus of morphine addicted mice after injected with ribozyme specially cleaving per1 mRNA. METHOD: The recombined plasmid pcDNA 3.1-per1RZ DNA was injected into the ventricles of morphine addicted mice to transcript the corresponding ribozyme which cleaves per1 mRNA particularly. And then, the brains of mice were fixed by perfusion. The level of c-fos mRNA was assayed by in situ hybridization and c-fos protein was detected by immunohistochemical staining. RESULT: The level of c-fos mRNA and protein decreased after injection of the recombined plasmid pcDNA 3.1-per1RZ DNA expressing the ribozyme cleaving per1 mRNA. CONCLUSION: The ribozyme specially cleaving per1 mRNA has potential function in inhibiting the transcription and expression of c-fos and blocking the morphine addiction.

Animals↗
PubMed2005

[Report of 4 cases ectopic meningioma of maxillary sinus in children and the review of relative literatures].

OBJECTIVE: To explore the clinical manifestation and diagnosis as well as the treatment of ectopic meningioma of maxillary sinus in children. METHOD: Four cases of ectopic meningioma of maxillary sinus in children were investigated with retrospective analysis and review of the literatures. RESULT: All the four cases presented progressing nasal obstruction and 1 case showed exophthalmos. Ball-like neoplasma in lateral wall of nasal cavity could be seen. CT revealed high density shadow and bone absorption around the lesion. The complete resection of neoplasma were performed. There was No relapse after 4 to 6 years following up. CONCLUSION: CT plays an inportmentrole in diagnosis of ectopic meningioma of maxillary sinus. The best method of treatment is to completely resect the

Child↗
PubMed2005

[Effect of isorhmnetin on circadian rhythms of DNA synthesis and expression of c-myc gene in Eca-109 cells of human oesophageal cancer].

This study was focused on the circadian rhythms of DNA synthesis and the expression of c-myc gene in untreated and treated Eca-109 cells in human oesophageal cancer with isorhmnetin. The circadian rhythms of 3H-TdR incorporation and expression of c-myc gene in untreated and treated Eca-109 cells were measured by 3H-thymidine uptake assay and flow cytometry. The data collected were analyzed by ANOVA and Cosinor method. DNA synthesis and expression of c-myc gene in untreated group varied according to circadian time with statistical significance, the distribution curves of both DNA synthesis and the expression level of c-myc were fit for cosinor changes. The circadian rhythms of DNA synthesis and circadian parameters of c-myc expression in treated Eca-109 cells changed. The circadian parameters of DNA synthesis and expression level of c-myc varied after treatment by isorhmnetin. The effects of isorhmnetin on cell proliferation and c-myc expression reached the highest level from 20: 00 to 0: 00. The results provide a guidance for instituting the chemotherapy and chronotherapy of human tumors, when isorhmnetin is for use as anti-cancer agent.

Circadian Rhythm↗
PubMed2004

Intestinal perforation after combined liver-kidney transplantation for a case of congenital polycystic disease.

AIM: To highlight the intestinal perforation (IP), an uncommon and catastrophic complication after combined liver-kidney transplantation. METHODS: Combined liver-kidney transplantation (LKTx) with left kidney excision and a cyst fenestration procedure on the right kidney were performed on a case of 46-year-old female with congenital polycystic disease (CPCD). RESULTS: Two sites of IP were noted 40-50 cm proximal to ileocecal area during emergent laparotomy 10 d postoperatively. Despite aggressive surgical and medical management, disease progressed toward a fatal outcome due to sepsis and multiple organ failure 11 d later. CONCLUSION: Long duration of operation without venovenous bypass, overdose of steroid together with postoperative volume excess may all contribute to the risk of idiopathic multiple IPs. Microbiology and pathology inspections suggested that the infected cyst of the fenestrated kidney might be one reason for the fatal intra-peritoneal infection. Thus for the CPCD patients who seem to be very susceptible to infectious complications, any sign of suspected renal-infection found before or during LKTx is indication for the excision of original kidney. And the intensity of immunosuppression therapy should be controlled cautiously.

Fatal Outcome↗
PubMed2004

A new peptide with membrane-permeable function derived from human circadian proteins.

Basic peptides such as human immunodeficiency virus type 1 (HIV-1) Tat-(48-60) and Drosophila Antennapedia-(43-58) have been reported to have a membrane permeability and a carrier function for intracellular protein delivery. Based on the fluorescence microscopic observations of the vascular endothelial cells (ECV-304) and the primary cultured neuroglial cells, we found that human Clock protein DNA-binding peptide [residue 35-47, hClock-(35-47)] had a translocation activity very similar to Tat-(48-60). The cellular uptake of hClock-(35-47) increases with the increase of incubation time and concentration. The internalization effect at 4 degrees was same as that at 37 degrees C. Internalization of hClock-(35-47) was saturable and could be inhibited by the excess of the other MPPs. Moreover, the uptake of these peptides were significantly inhibited in the presence of heparan sulfate. These results strongly suggested that the hClock-(35-47) shared a common or very similar internalization pathway with other MPPs. Furthermore, we injected rat through the common carotid artery with hClock-(35-47)-FITC peptide, and cryostat sections of the brain were prepared and observed using a fluorescence microscope. Result showed that the peptide had the ability to translocate through the blood-brain barrier. It is promising to provide a new safe carrier for the intracellular and encephalic treatment.

Amino Acid Sequence↗
PubMed2004

SPR fingerprinting of mismatched base pair.

Discrimination of mismatched base pairs having various flanking sequence from normal Watson-Crick base pairs were examined using SPR sensor surface where mismatch binding ligand (MBL) were immobilized. CC, CT, and TT mismatched base pair are distinguishable from wild type DNA by means of diaminonaphthyndine dimer (damND) immobilized sensor surface. By comparing the component ratio of responses obtained by MLB immobilized sensors, distinct differences could be observed between mismatched base pairs having almost the same total SPR response.

Base Pair Mismatch↗
PubMed2004

[The expression of apoptosis-associated proteins Bcl-2, Bax in oral leukoplakia and lichen planus].

PURPOSE: The purpose of this study was to explore the pathogenesis and carcinogenesis of oral leukoplakia (LK) and oral lichen planus (OLP) by examining the expression of apoptosis-associated proteins Bcl-2 Bax in LK and OLP. METHODS: The expression of Bcl-2 and Bax were measured in 10 cases of normal oral mucosa,18 cases of OLP, 23 cases of LK and 22 cases of oral squamous cell carcinoma (SCC) by immunohistochemical assays. RESULTS: In the epithelial cell layer of LK and OLP, the positive Bcl-2 expression was similar to oral normal mucosa,but in the part of the lymphocytic infiltration of OLP, overexpression of Bcl-2 was observed. In the SCC, the Bcl-2 expression was significantly higher than that in normal oral mucosa(P<0.05). In the tissue of simple hyperplasia, mild dysplasia, moderate dysplasia, poorly differentiated SCC and erosive OLP, the expression of Bax was significantly higher than that in normal oral mucosa (P<0.05). CONCLUSIONS: Bax was closely related to the early event of LK carcinogenesis. Bcl-2 may not play a role in LK carcinogenesis. Bcl-2 and Bax play an important role in pathogenesis of OLP. We postulate that the Bcl-2 inhibits the apoptosis of lymphocytes that strengthen the cell-mediated immune process and the overexpression of Bax was related to the apoptosis of epithelial cells in OLP.

Apoptosis↗
PubMed2004

[The role of circadian gene period1 in morphine reward in mice].

OBJECTIVE: To investigate the role of circadian gene Period1 on drug dependence. METHOD: The ribozyme cleave the Period1 mRNA (per1RZ) was designed and the per1RZ expression vector (pcDNA 3.1-per1RZ) was constructed based on eukaryotic expression vector pcDNA 3.1. In vitro cleavage experiment proved the target cleave Period1 mRNA ability of per1RZ. Conditional place preference (CPP) paradigm used to investigate the effect of intracerebroventricular (ICV) injection of pcDNA 3.1-per1RZ on drug reward in BALB/C mice. RESULT: Quantitative analysis of in vitro cleavage experiment showed the efficacy of ribozyme per1RZ, about 60% of the Period1 mRNA was cleaved by ribozyme per1RZ. CPP test displayed the block of drug reward in pcDNA 3.1-per1RZ ICV injection group. Period1 expression in brain was attenuated of pcDNA 3.1-per1RZ ICV injection group demonstrated by western blot. CONCLUSION: Interfere the Period1 expression in brain could attenuate the psychological dependence of drug in mammals.

Animals↗
PubMed2003

Essential roles of lipoyl domains in the activated function and control of pyruvate dehydrogenase kinases and phosphatase isoform 1.

Four pyruvate dehydrogenase kinase and two pyruvate dehydrogenase phosphatase isoforms function in adjusting the activation state of the pyruvate dehydrogenase complex (PDC) through determining the fraction of active (nonphosphorylated) pyruvate dehydrogenase component. Necessary adaptations of PDC activity with varying metabolic requirements in different tissues and cell types are met by the selective expression and pronounced variation in the inherent functional properties and effector sensitivities of these regulatory enzymes. This review emphasizes how the foremost changes in the kinase and phosphatase activities issue from the dynamic, effector-modified interactions of these regulatory enzymes with the flexibly held outer domains of the core-forming dihydrolipoyl acetyl transferase component.

Animals↗