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Biomedical subjects

Q Yuan

Publications and source records attributed to Q Yuan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Anchoring of rice BAC clones to the rice genetic map in silico.

A wealth of molecular resources have been developed for rice genomics, including dense genetic maps, expressed sequence tags (ESTs), yeast artificial chromosome maps, bacterial artificial chromosome (BAC) libraries and BAC end sequence databases. Integration of genetic and physical maps involves labor-intensive empirical experiments. To accelerate the integration of the bacterial clone resources with the genetic map for the International Rice Genome Sequencing Project, we cleaned and filtered the available EST and BAC end sequences for repetitive sequences and then searched all available rice genetic markers with our filtered databases. We identified 418 genetic markers that aligned with at least one BAC end sequence with >95% sequence identity, providing a set of large insert clones with an average separation of 1 Mb that can serve as nucleation points for the sequencing phase of the International Rice Genome Sequencing Project.

Chromosome Mapping↗
PubMed2000

Effects of neurotrophic factors on motoneuron survival following axonal injury in newborn rats.

Using two different lesion models, the spinal root avulsion and the distal nerve axotomy, the present study investigated effects of known neurotrophic factors on motoneuron survival in newborn rats. Results of the present study show that 100% of motoneurons in the lesioned spinal segment die at 1 week following root avulsion, and more than 80% of them die at 2 weeks following distal nerve axotomy. Local application of GDNF can rescue 92% of motoneurons up to 1 week from degeneration due to root avulsion and almost 100% of them up to 2 weeks from degeneration due to distal nerve axotomy. Local application of BDNF fails to prevent any motoneuron death in newborn rats following root avulsion, but it can rescue about 50% of motoneurons up to 2 weeks from degeneration due to distal nerve axotomy. CNTF and IGF-1 fail to prevent any motoneuron death following either distal nerve axotomy or root avulsion. Thus, comparing all the neurotrophic factors tested in this study, GDNF is most effective in preventing death of motoneurons following axonal injury in newborn rats.

Animals↗
PubMed2000

Mapping of spinocerebellar ataxia 13 to chromosome 19q13.3-q13.4 in a family with autosomal dominant cerebellar ataxia and mental retardation.

We examined a large French family with autosomal dominant cerebellar ataxia (ADCA) that was excluded from all previously identified spinocerebellar ataxia genes and loci. The patients-seven women and a 4-year-old boy-exhibited slowly progressive childhood-onset cerebellar gait ataxia associated with cerebellar dysarthria, moderate mental retardation (IQ 62-76), and mild developmental delays in motor acquisition. Nystagmus and pyramidal signs were also observed in some cases. This unique association of clinical features clearly distinguishes this new entity from other previously described ADCA. Cerebral magnetic-resonance imaging showed moderate cerebellar and pontine atrophy in two patients. We performed a genomewide search and found significant evidence for linkage to chromosome 19q13.3-q13.4, in an approximately 8-cM interval between markers D19S219 and D19S553.

Adult↗
PubMed2000

Dominant negative down-regulation of endotoxin-induced tumor necrosis factor alpha production by Lps(d)/Ran.

We recently showed that adenoviral transfer and expression of the Lps(d)/Ran gene isolated from endotoxin-resistant C3H/HeJ mice could protect endotoxin-sensitive mice from endotoxic shock. Elevation of proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha), is thought to be essential for the development of septic shock. To investigate the extent to which Lps(d)/Ran affects TNF-alpha production, we transduced primary macrophages from endotoxin-sensitive and -resistant mice with adenoviral vectors expressing the wild-type and the mutant Lps/Ran cDNAs and other control genes, and compared the amount of TNF-alpha produced by these various transduced macrophages. Successful transfer and expression of Lps(d)/Ran cDNA in endotoxin-sensitive C3H/HeOuJ macrophages reduced TNF-alpha production upon lipopolysaccharide (LPS) stimulation, as compared with macrophages transduced with vectors expressing the wild-type Lps(n)/Ran cDNA, the green fluorescent protein gene, or the lacZ gene. On the other hand, successful transfer and expression of the wild-type Lps(n)/Ran cDNA in primary macrophages from endotoxin-resistant C3H/HeJ mice failed to induce TNF-alpha production to any significant extent unless a very high LPS concentration was used. Given our previous demonstration that Lps(n)/Ran functions effectively in restoring LPS responsiveness in B cells from C3H/HeJ mice, we conclude that Lps/Ran is involved in a CD14-independent signal transduction pathway. This dominant negative down-regulation by Lps(d)/Ran on TNF-alpha production by macrophages and probably other innate immune responses may be key to the development of an effective gene therapy for endotoxic or septic shock.

Adenoviridae↗
PubMed2000

Cardiac-respiratory gating method for magnetic resonance imaging of the heart.

In studies of transmural myocardial function, acquisitions of high spatial and temporal resolution tagged cardiac images often exceed the practical time limit for breath-hold fast imaging techniques. Therefore, a dual cardiac-respiratory gating device has been constructed to acquire SPAMM-tagged cardiac MR images at or near end-expiration during spontaneous breathing, by providing an external trigger to a conventional MRI system. Combined cardiac and respiratory gating essentially eliminates the respiratory motion artifacts in tagged cardiac MR images. Compared to cardiac-gated images obtained during intermittent breath-holds, cardiac-respiratory gated images show improved tag-myocardium contrast due to magnetization recovery during inspiration.

Analysis of Variance↗
PubMed2000

Expression of a functional antizearalenone single-chain Fv antibody in transgenic Arabidopsis plants.

The efficacy of cloning a recombinant mycotoxin antibody in plants was tested using Arabidopsis as a model. An antizearalenone single-chain Fv (scFv) DNA fragment was first cloned in the newly constructed phage display vector (pEY.5) and then recloned in the plant transformation vector pKYLX71::35S(2). After transformation, constructs of antizearalenone scFv were introduced into immature Arabidopsis seeds via Agrobacterium tumefaciens mediation by vacuum infiltration. Only plants transformed with the construct containing a PR-1b signal peptide sequence produced transgenic offspring. The antizearalenone scFv "plantibody" from these transgenic plants bound zearalenone with a high affinity (50% inhibitory concentration, 11.2 ng/ml) that was comparable to that of bacterially produced scFv antibody and the parent monoclonal antibody (MAb). By electron microscopic immunogold labeling, the presence of antizearalenone scFv was detected mainly in the cytoplasm and only occasionally outside the cell. Like bacterially produced scFv antibody, antizearalenone scFv plantibody exhibited greater sensitivity to methanol destabilization than did the parent MAb. The sensitivity of antizearalenone scFv plantibody to acidic disassociation was similar to the sensitivities of bacterially produced scFv antibody and MAb. Expression of specific plantibodies in crops might be useful for neutralizing mycotoxins in animal feeds and for reducing mycotoxin-associated plant diseases.

Antibody Formation↗
PubMed2000

Polyamine depletion delays apoptosis of rat intestinal epithelial cells.

The polyamines spermidine, spermine, and their precursor putrescine are essential for cell growth and the regulation of the cell cycle. Recent studies suggest that excessive accumulation of polyamines favors either malignant transformation or apoptosis, depending on the cell type and the stimulus. This study examines the involvement of polyamines in the induction of apoptosis by the DNA topoisomerase I inhibitor, camptothecin. In IEC-6 cells, camptothecin induced apoptosis within 6 h, accompanied by detachment of cells. Detached cells showed DNA laddering and caspase 3 induction, characteristic features of apoptosis. Depletion of putrescine, spermidine, and spermine by DL-alpha-difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (ODC) that is the first rate-limiting enzyme for polyamine biosynthesis, decreased the apoptotic index. Delayed apoptosis was accompanied by a decrease in caspase 3 activity in polyamine-depleted cells. Addition of putrescine restored the induction of apoptosis as indicated by an increase in the number of detached cells and caspase 3 activity. Polyamine depletion did not change the level of caspase 3 protein. Inhibition of S-adenosylmethionine decarboxylase by a specific inhibitor [diethylglyoxal bis-(guanylhydrazone); DEGBG] led to depletion of spermidine and spermine with a significant accumulation of putrescine and induction of ODC. The DEGBG-treated cells showed an increase in apoptosis, suggesting the importance of putrescine in the apoptotic process. Addition of putrescine to DFMO-treated cell extracts did not increase caspase 3 activity. The above results indicate that polyamine depletion delays the onset of apoptosis in IEC-6 cells and confers protection against DNA damaging agents, suggesting that polyamines might be involved in the caspase activating signal cascade.

Animals↗
PubMed2000

Putrescine does not support the migration and growth of IEC-6 cells.

The migration of IEC-6 cells is inhibited when the cells are depleted of polyamines by inhibiting ornithine decarboxylase with alpha-difluoromethylornithine (DFMO). Exogenous putrescine, spermidine, and spermine completely restore cell migration inhibited by DFMO. Because polyamines are interconverted during their synthesis and catabolism, the specific role of individual polyamines in intestinal cell migration, as well as growth, remains unclear. In this study, we used an inhibitor of S-adenosylmethionine decarboxylase, diethylglyoxal bis(guanylhydrazone)(DEGBG), to block the synthesis of spermidine and spermine from putrescine. We found that exogenous putrescine does not restore migration and growth of IEC-6 cells treated with DFMO plus DEGBG, whereas exogenous spermine does. In addition, the normal distribution of actin filaments required for migration, which is disrupted in polyamine-deficient cells, could be achieved by adding spermine but not putrescine along with DFMO and DEGBG. These results indicate that putrescine, by itself, is not essential for migration and growth, but that it is effective because it is converted into spermidine and/or spermine.

Actins↗
PubMed2000

Inhibition of oncogene STAT3 phosphorylation by a prolactin antagonist, hPRL-G129R, in T-47D human breast cancer cells.

We have previously demonstrated that a hPRL antagonist (hPRL-G129R) was able to inhibit PRL induced breast cancer cell proliferation through induction of apoptosis. In the present study, we test the hypothesis that the inhibitory effect of hPRL-G129R in breast cancer cells occurs, at least in part, through the inhibition of oncogene STAT3 activation. We first demonstrated that STAT5 and STAT3 could be activated by either hGH or hPRL in T-47D breast cancer cells. Although the patterns of STAT5 activation by hGH and hPRL are similar, we observed a nearly 10-fold greater efficacy of hPRL in STAT3 activation as compared to that of hGH. More importantly, we have demonstrated that activation of STAT3 by hPRL could be inhibited by hPRL-G129R. Since T-47D cells coexpress GHR and PRLR, an attempt was made to dissect the molecular events mediated through hGHR or hPRLR using mouse L-cells expressing a single population of receptors (hGHR or hPRLR). To our surprise, only STAT5, not STAT3 phosphorylation was observed in these L-cells. In conclusion, our results suggest that: a) STAT3 is preferably activated through hPRLR in T-47D cells; b) hPRL-G129R is effective in inhibiting STAT3 phosphorylation; and c) the mechanism of STAT3 activation is different from that of STAT5.

Amino Acid Substitution↗
PubMed2000

[Targeting studies of humanized scFv25 fusing to TNFalpha against hepatocellular carcinoma].

OBJECTIVE: To obtain humanized engineering bifunctional antibody, which has potentialities for clinical application. METHODS: Humanized anti-human hepatocellular carcinoma (HCC) single chain fragment (hscFv25) was linked with human TNF-alpha gene to form anti-HCC bifunctional antibody, then it was subcloned into prokaryotic GST fusion expression vector pGEX 4T-1 and expressed in the host E.coli. Indirect immunofluorescent staining was performed on HCC cell smearing slides in order to evaluate the activity of the purified aim protein, then MTT trial to evaluate the cytotoxicity of hscFv25-TNFalpha to SMMC-7721, finally primary tumor regression trial in nude mice bearing HCC to evaluate the targeting therapeutic value of hscFv25-TNFalpha. RESULTS: The hscFv25-TNFalpha had the similar specificity to parental antibody HAb25 for SMMC-7721 antigen. One hour predisposed MTT trial in control with parental antibody HAb25 affirmed that hscFv25-TNFalpha was cytotoxic to targeted cell SMMC-7721 with the IC(50) to be 7.1 microg/ml. The cytotoxicity can be inhibited by parental antibody HAb25. This indicated that the cytotoxicity of hscFv25-TNFalpha to targeted cell is antibody-mediated selective cytotoxicity. The tumor regression trial to the 3mm HCC xenografts in nude mice showed that hscFv25-TNFalpha had assured targeting cytotoxicity and the efficiency was nearly up to 3/3 (1/3 complete remission, 2/3 partial remission). The cytotoxicity of the hscFv25-TNFalpha was better than that of TNFalpha, whose efficiency was only 2/3 and without complete remission. CONCLUSION: hscFv25-TNFalpha is an anti-HCC bi-functional antibody which has potentialities for clinical application.

Animals↗
PubMed2000

[Analysis of the construction of creature valves frame].

This paper analyses the construction of the creature valves frame according as the theory of Membrane in order to enable the creature valves to take the place of cardial valves of human being. It provides solid theoretical foundations for building the mathematical model and computer-aided design of the creature valves frame.

Heart Valve Prosthesis↗
PubMed2000

[Effects of noise and music on EEG power spectrum].

Objective. To observe the effect of noise and music on EEG power spectrum. Method. 12 healthy male pilots aged 30 +/- 0.58 years served as the subjects. Dynamic EEG from 16 regions was recorded during quiet, under noise or when listening to music using Oxford MR95 Holter recorder. Changes of EEG power spectrum of delta, theta, alpha1, alpha2, beta1 and beta2, frequency components in 16 regions were analyzed. Result. The total alpha1 power was significantly decreased, while the total theta power was significantly increased when listening to music; It implies that the interhemispheric transmission of information in the frontotemporal areas might be involved. Conclusion. The changes of the EEG power spectrum were closely related to man's emotions; relaxation was associated with music; Individual difference exists in the influence of sound on EEG.

Adult↗
PubMed2000

[Construction and expression of single-chain Fv antibody against human VEGF].

OBJECTIVE: Binding specificity of a monoclonal antibody (MAb) (gamma. k 2b) E11 which can react with the peptide of human VEGF was determined by ELISA and immunohistochemistry. The E11 primarily proved to be potential activity of suppressing tumor growth in vivo. The construction and expression of engineering antibody (ScFv) could widen application of this MAb in both diagnosis and treatment of human cancer. METHODS: From the hybridoma cell line secreting MAb against VEGF, total RNA was prepared and used as a template for cDNA synthesis and cloning. Reverse transcription and polymerase chain reaction (RT-PCR) were used to clone the immunoglobulin variable region gene (VH, VL). The cloned VH and VL were linked by well documented flexible peptide bridging sequence (GGGGS) 3 in the VH-linker-VL orientation. The constructed ScFv gene was inserted into pET-15b and expressed in E.coli BL21 (DE3). Biding activity of ScFv was evaluated by ELISA and immunohistochemical methods after its denature and renature treatment. RESULTS: The sequence analysis revealed that the full length of VH was 369 bp, and VL was 333 bp. According to Kabat classification, VH and VL are the member of mouse Ig variable gene heavy chain subgroup II (A) and light chain subgroup III, respectively. The ScFv was highly expressed in the form of inclusion bodies which activity was recovered after being renatured. Immunohistochemical results showed that ScFv retained almost the same antigen affinity and specificity as its parent monoclonal antibody. CONCLUSIONS: Recombinant antibody ScFv is potential in both diagnostic and therapeutic application of human malignant tumors.

Animals↗
PubMed2000

[Transoral microsurgical treatment of craniocervical malformation].

OBJECTIVE: To discuss transoral microcervical treatment of 16 patients with craniocervical malformation. METHODS: Perioperative treatment including antibiotics, tracheotomy, intravenous nutrition was used in 16 patients. RESULTS: Eight patients had basilar impressions, 3 chronic atlantoaxial dislocation and 2 odontoid fracture, 2 lower clivus chordoma, and 1 granuloma in the ventral part of the medulla oblongata. Three patients received bone graft. Follow-up for 6 - 36 months showed that 14 patients resumed normal life but 1 died. CONCLUSIONS: Pre-craniocervical malformation can be treated by transoral approach microsurgically. Understanding microanatomy of this approach can reduce postoperative morbidity and complications. Perioperative treatment can prevent incision infection. Prevention of intraoperative CSF leakage must be emphasized.Bone graft can make craniocervical spine stable.

Adolescent↗
PubMed2000

[Cervical spine operation using coralline hydroxyapatite].

OBJECTIVE: To study the result of using coralline hydroxyapatite (CHA) in cervical anterior fusion and posterior laminoplasty operation. METHODS: 45 patients of cervical operation using CHA were followed up. Of these patients, 27 received anterior fusion and titanium plate fixation (34 levels fused). 18 with spinal stenosis at least at 3 levels, (posterior spinal process-splitting laminoplasty) had 79 split spinal processes fused by CHA. The average follow-up time was 25.9 months. RESULTS: The union rate of CHA was 85.3% in average by anterior approach. The height and angle of the fused level and the anterior salient were well maintained. The JOA score improvement rate was 58.7%. The CHA grafts were kept well between the split spinous processes with a union rate of 70.9%. After operation, the spinal cord moved dorsally, and the flat rate was improved from 0.19 to 0.41. No apparent posterior salient occurred. The JOA score improvement rate was 51%. CONCLUSION: The effect of CHA in cervical antero posterior operation is similar to that of autograft bone, and it is unnecessary to resect a piece of bone from a health region of the body.

Adult↗
PubMed1999

Lps(d)/Ran of endotoxin-resistant C3H/HeJ mice is defective in mediating lipopolysaccharide endotoxin responses.

C3H/HeJ inbred mice are defective in that they are highly resistant to endotoxic shock as compared with normal responder mice. Their B cells and macrophages do not respond significantly when exposed to lipopolysaccharide (LPS), whereas cells from the responder mice do. Using a functional assay, we previously isolated a cDNA, which encodes for Ran/TC4 GTPase. We now show that this gene is mutated in C3H/HeJ mice, which accounts for their resistance to endotoxin stimulation. Sequence analysis of independent mutant Lps(d)/Ran cDNAs isolated from splenic B cells of C3H/HeJ mice reveals a consistent single base substitution at position 870, where a thymidine is replaced with a cytidine. In situ hybridization maps the Lps(d)/Ran cDNA to mouse chromosome 4. By retroviral gene transfer, the wild-type Lps(n)/Ran cDNA but not the mutant Lps(d)/Ran cDNA can restore LPS responsiveness of C3H/HeJ cells. Adenoviral gene transfer in vivo with the mutant Lps(d)/Ran cDNA but not the wild-type Lps(n)/Ran cDNA rescues endotoxin-sensitive mice from septic shock. Thus Lps/Ran is an important target for LPS-mediated signal transduction, and the Lps(d)/Ran gene may be useful as a therapeutic sequence in gene therapy for endotoxemia and septic shock.

3' Untranslated Regions↗
PubMed1999

T helper cell type 2 cytokine-mediated comitogenic responses and CCR3 expression during differentiation of human mast cells in vitro.

Mast cells (MCs) arise in situ from circulating stem cell factor (SCF)-dependent committed progenitors (PrMCs) and accumulate at sites of allergic mucosal inflammation. We hypothesized that human (h)PrMCs and their mature counterparts might share overlapping patterns of chemokine and cytokine receptor utilization with eosinophils, basophils, and T helper type 2 (Th2) lymphocytes for their homing and allergy-associated hyperplasia. We have characterized committed hPrMCs and fully mature hMCs derived in vitro from cord blood for their functional responses to chemokine and cytokine agonists germane to allergic inflammation and for their maturation-related expression of the corresponding receptors. After 4 wk of culture in the presence of recombinant stem cell factor (SCF), interleukin (IL)-6, and IL-10, the cells were characterized as hPrMCs based upon their uniform surface expression of c-kit and CD13, low-level expression of FcinRIalpha, absence of CD14 and CD16 expression, and immunoreactivity for MC chymase in >80%, and about half were immunoreactive for tryptase and metachromatic with toluidine blue. By week 9, the cells had matured into hMCs, identified by higher levels of c-kit, continued expression of CD13 and low-level FcinRIalpha, uniform toluidine blue metachromasia, and uniform immunoreactivity for both tryptase and chymase. The 4-wk-old hPrMCs expressed four chemokine receptors (CXCR2, CCR3, CXCR4, and CCR5). Each receptor mediated transient rapid calcium fluxes in response to its respective ligand. Both recombinant human eotaxin and stromal cell-derived factor 1alpha elicited chemotaxis of hPrMCs. Only CCR3 was retained on the mature 9-wk-old hMCs from among these chemokine receptors, and hMCs responded to eotaxin with a sustained calcium flux but without chemotaxis. The Th2 cytokines IL-3, IL-5, IL-6, IL-9, and granulocyte/macrophage colony-stimulating factor each augmented the SCF-dependent proliferation of hPrMCs and hMCs. In contrast, the prototypical Th1 cytokine, interferon gamma, suppressed SCF-driven proliferation of both hPrMCs and hMCs. Thus, throughout their development in vitro, hMCs obey SCF-dependent, cytokine-driven mitogenic responses that reflect a Th2-type polarization characteristic of allergy and asthma. Furthermore, committed hPrMCs have a unique profile of chemokine receptor expression from among reported hematopoietic cells, including CCR3, which is shared with the other cells central to allergic inflammation (eosinophils, basophils, and Th2 lymphocytes).

Cell Differentiation↗